Prefabrication of axial vascularized tissue engineering coral bone by an arteriovenous loop: A better model

International Nuclear Information System (INIS)

Dong Qingshan; Shang Hongtao; Wu Wei; Chen Fulin; Zhang Junrui; Guo Jiaping; Mao Tianqiu

2012-01-01

The most important problem for the survival of thick 3-dimensional tissues is the lack of vascularization in the context of bone tissue engineering. In this study, a modified arteriovenous loop (AVL) was developed to prefabricate an axial vascularized tissue engineering coral bone in rabbit, with comparison of the arteriovenous bundle (AVB) model. An arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. It was placed in a circular side groove of the coral block. The complex was wrapped with an expanded-polytetrafluoroethylene membrane and implanted beneath inguinal skin. After 2, 4, 6 and 8 weeks, the degree of vascularization was evaluated by India ink perfusion, histological examination, vascular casts, and scanning electron microscopy images of vascular endangium. Newly formed fibrous tissues and vasculature extended over the surfaces and invaded the interspaces of entire coral block. The new blood vessels robustly sprouted from the AVL. Those invaginated cavities in the vascular endangium from scanning electron microscopy indicated vessel's sprouted pores. Above indexes in AVL model are all superior to that in AVB model, indicating that the modified AVL model could more effectively develop vascularization in larger tissue engineering bone. - Highlights: ► A modified arteriovenous loop (AVL) model in rabbit was developed in this study. ► Axial prevascularization was induced in a larger coral block by using the AVL. ► The prefabrication of axial vascularized coral bone is superior as vascular carrier.

Simultaneous Iliac Vein Bovine Pericardial Patch Venoplasty and Creation of PTFE Lower Limb Arteriovenous Fistula Graft for Rescue Vascular Access.

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Meecham, Lewis; Fisher, Owain; Kirby, George; Evans, Richard; Buxton, Pauline; Legge, Jocelyn; Rajagopalan, Sriram; Asquith, John; Pherwani, Arun

2016-10-01

We present a case of external iliac vein patch venoplasty to accommodate rescue vascular access via a polytetrafluoroethylene loop arteriovenous fistula graft (AVG) for a patient with multiple central venous stenoses. A 35-year-old female with anti-glomerular basement membrane antibody disease required rescue vascular access for hemodialysis. Repeated occlusion and/or thrombosis of long-term central venous access cannulae, to facilitate dialysis, had caused stenosis of brachiocephalic veins: right external iliac vein and occlusion of the left common iliac vein. A previous right brachiobasilic fistula had occluded within 1 year. No other upper limb options for arteriovenous fistula (AVF) were available. A right external iliac vein bovine patch angioplasty concurrently with a polytetrafluoroethylene AV graft between common femoral artery and common femoral vein was performed to restore venous patency and allow rescue dialysis access. At 3-year follow-up, the fistula remains widely patent with 2 L/min flow rates and no recurrent stenosis to the treated iliac vein. She has not required any further surgical or interventional radiological procedures to maintain fistula or central venous patency. Central venous stenosis or occlusion is common for patients requiring dialysis, especially those with multiple previous long-term central venous cannulations. If restriction of outflow is present, AVF may fail. Venous patch angioplasty in these cases is a successful technique, allowing AVF formation and long-term patency. Central venous stenosis can be treated successfully with patch venoplasty to accommodate AVF/AVG formation for rescue vascular access; this is a potentially lifesaving intervention for patients requiring dialysis. Copyright © 2016 Elsevier Inc. All rights reserved.

Maxillary reconstruction with a double-barrel osteocutaneous fibular flap and arteriovenous saphenous loop after a globe-sparing total maxillectomy-A Case Report.

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Chen, Szu-Han; Hung, Kuo-Shu; Lee, Yao-Chou

2017-05-01

Maxillary reconstruction using titanium mesh or bone grafts can invite unwanted complications, such as graft resorption, infection, and mesh exposure, especially for patients who require postoperative radiotherapy. Here, we reported a 58-year-old male patient who was diagnosed with maxillary sinus squamous cell carcinoma. The patient received cancer ablation by a globe-sparing total maxillectomy and was immediately reconstructed with a double-barrel osteocutaneous fibular flap to simultaneously restore the alveolar ridge, orbital support, and oro-sinonasal separation. The short pedicle length inherent in the double-barrel design of the fibular flap and the depletion of healthy recipient vessels in the midface after cancer ablation were overcome by creating an arteriovenous saphenous loop in the neck region. Though there was venous congestion on postoperative day 2, the postoperative recovery was uneventful after the revision of the venous anastomoses. During the 6-months follow-up, the outcome was functionally and aesthetically satisfactory. We believe that the double-barrel fibular osteocutaneous flap, which avoids using titanium mesh and bone grafts, may be a viable reconstructive option in cancer patients with globe-sparing total maxillectomy defects, especially for those who require postoperative radiotherapy. © 2015 Wiley Periodicals, Inc. Microsurgery 37:334-338, 2017. © 2015 Wiley Periodicals, Inc.

Arteriovenous fistula of the superior gluteal artery as a complication of posterior iliac crest bone graft harvesting: 3D-CT angiography and arterial embolization

OpenAIRE

Kong, Chae-Gwan; Park, Jong-Beom; Won, Yoo-Dong; Riew, K. Daniel

2009-01-01

Superior gluteal artery injuries are rare, but potentially serious complications that occur during posterior iliac crest bone graft harvesting. The authors reported an arteriovenous fistula of the superior gluteal artery, which occurred as a complication during posterior iliac crest bone graft harvesting and was diagnosed with 3D-CT angiography, then treated with arterial embolization.

Prefabrication of axial vascularized tissue engineering coral bone by an arteriovenous loop: a better model.

Science.gov (United States)

Dong, Qing-shan; Shang, Hong-tao; Wu, Wei; Chen, Fu-lin; Zhang, Jun-rui; Guo, Jia-ping; Mao, Tian-qiu

2012-08-01

The most important problem for the survival of thick 3-dimensional tissues is the lack of vascularization in the context of bone tissue engineering. In this study, a modified arteriovenous loop (AVL) was developed to prefabricate an axial vascularized tissue engineering coral bone in rabbit, with comparison of the arteriovenous bundle (AVB) model. An arteriovenous fistula between rabbit femoral artery and vein was anastomosed to form an AVL. It was placed in a circular side groove of the coral block. The complex was wrapped with an expanded-polytetrafluoroethylene membrane and implanted beneath inguinal skin. After 2, 4, 6 and 8 weeks, the degree of vascularization was evaluated by India ink perfusion, histological examination, vascular casts, and scanning electron microscopy images of vascular endangium. Newly formed fibrous tissues and vasculature extended over the surfaces and invaded the interspaces of entire coral block. The new blood vessels robustly sprouted from the AVL. Those invaginated cavities in the vascular endangium from scanning electron microscopy indicated vessel's sprouted pores. Above indexes in AVL model are all superior to that in AVB model, indicating that the modified AVL model could more effectively develop vascularization in larger tissue engineering bone. Copyright © 2012 Elsevier B.V. All rights reserved.

Modulation of friction dynamics in water by changing the combination of the loop- and graft-type poly(ethylene glycol) surfaces.

Science.gov (United States)

Seo, Ji-Hun; Tsutsumi, Yusuke; Kobari, Akinori; Shimojo, Masayuki; Hanawa, Takao; Yui, Nobuhiko

2015-02-07

A Velcro-like poly(ethylene glycol) (PEG) interface was prepared in order to control the friction dynamics of material surfaces. Graft- and loop-type PEGs were formed on mirror-polished Ti surfaces using an electrodeposition method with mono- and di-amine functionalized PEGs. The friction dynamics of various combinations of PEG surfaces (i.e., graft-on-graft, loop-on-loop, graft-on-loop, and loop-on-graft) were investigated by friction testing. Here, only the Velcro-like combinations (graft-on-loop and loop-on-graft) exhibited a reversible friction behavior (i.e., resetting the kinetic friction coefficient and the reappearance of the maximum static friction coefficient) during the friction tests. The same tendency was observed when the molecular weights of loop- and graft-type PEGs were tested at 1 k and 10 k, respectively. This indicates that a Velcro-like friction behavior could be induced by simply changing the conformation of PEGs, which suggests a novel concept of altering polymer surfaces for the effective control of friction dynamics.

Endovascular management of renal transplant dysfunction secondary to hemodynamic effects related to ipsilateral femoral arteriovenous graft

Science.gov (United States)

Salsamendi, Jason; Pereira, Keith; Quintana, David; Bleicher, Drew; Tabbara, Marwan; Goldstein, Michael; Narayanan, Govindarajan

2016-01-01

Hemodialysis access options become complex in long-term treatment for patients with renal disease, while awaiting renal transplantation (RT). Once upper extremity sites are exhausted, lower extremities are used. RT is preferably in the contralateral iliac fossa, rarely ipsilateral. In current literature, RT dysfunction secondary to the hemodynamic effects of an ipsilateral femoral arteriovenous graft (AVG) has been rarely described. To our knowledge, AVG ligation is the only published technique for hemodynamic correction of an ipsilateral AVG. We present a simple, potentially reversible endovascular approach to manage the hemodynamic effects of an AVG, without potentially permanently losing future AVG access. PMID:26899147

Total Maxillary Reconstruction With a Bi-Paddle Double-Barrel Osteocutaneous Fibular Flap and Arteriovenous Saphenous Loop After a Globe-Sparing Total Maxillectomy Due to Osteosarcoma.

Science.gov (United States)

Tseng, Wan-Ling; Chang, Tzu-Yen; Hung, Kuo-Shu; Chen, Szu-Han; Hsiao, Jenn-Ren; Lee, Yao-Chou

2017-01-01

The titanium mesh or bone graft is usually used for orbital support after a globe-sparing total maxillectomy. However, its use can invite complications, such as infection, exposure, and absorption, especially for patients who require adjuvant radiotherapy. Here, the authors present a patient who received total maxillary reconstruction with an osteocutaneous fibular flap. A 53-year-old man with the diagnosis of maxillary osteosarcoma received a globe-sparing total maxillectomy. A bi-paddle double-barrel osteocutaneous fibular flap was used for orbital support, alveolar ridge recreation, and oro-sino-nasal separation. The short pedicle length inherent in the double-barrel design of the fibular flap was overcome by creating an arteriovenous saphenous loop. The postoperative recovery was uneventful. During the 9 months follow-up, the patient was tumor-free and satisfied with his appearance, speech, and intake functions. Reconstruction with a bi-paddle double-barrel osteocutaneous fibular flap after a globe-sparing total maxillectomy can achieve satisfactory aesthetic and functional results.

MDCT angiography with 3D image reconstructions in the evaluation of failing arteriovenous fistulas and grafts in hemodialysis patients

Energy Technology Data Exchange (ETDEWEB)

Dimopoulou, Angeliki; Raland, Hans; Magnusson, Anders (Dept. of Radiology, Univ. Hospital, Uppsala (Sweden)), email: angeliki.dimopoulou@akademiska.se; Wikstroem, Bjoern (Dept. of Medical Sciences, Renal Section, Univ. Hospital, Uppsala (Sweden))

2011-11-15

Background. Arteriovenous fistulas and grafts are the methods of choice for vascular access in renal failure patients in need of hemodialysis. Their major complication, however, is stenosis, which might lead to thrombosis. Purpose. To demonstrate the usefulness of 16-MDCTA with 3D image reconstructions, in long-term hemodialysis patients with dysfunctional arteriovenous fistulas and grafts (AVF and AVG). Material and Methods. During a 17-month period, 31 patients with dysfunctional AVF and AVG (24 AVF and seven AVG) were examined with MDCTA with 3D image postprocessing. Parameters such as comprehension of the anatomy, quality of contrast enhancement, and pathological vascular changes were measured. DSA was then performed in 24 patients. Results. MDCTA illustrated the anatomy of the AVF/AVG and the entire vascular tree to the heart, in a detailed and comprehensive manner in 93.5% of the evaluated segments, and depicted pathology of AVF/AVG or pathology of the associated vasculature. MDCTA demonstrated a total of 38 significant stenoses in 25 patients. DSA verified 37 stenoses in 24 patients and demonstrated two additional stenoses. MDCTA had thus a sensitivity of 95%. All 24 patients were treated with percutaneous transluminal angioplasty (PTA) with good technical results. Conclusion. MDCTA with 3D reconstructions of dysfunctioning AVFs and AVGs in hemodialysis patients is an accurate and reliable diagnostic method helping customize future intervention

MDCT angiography with 3D image reconstructions in the evaluation of failing arteriovenous fistulas and grafts in hemodialysis patients

International Nuclear Information System (INIS)

Dimopoulou, Angeliki; Raland, Hans; Magnusson, Anders; Wikstroem, Bjoern

2011-01-01

Background. Arteriovenous fistulas and grafts are the methods of choice for vascular access in renal failure patients in need of hemodialysis. Their major complication, however, is stenosis, which might lead to thrombosis. Purpose. To demonstrate the usefulness of 16-MDCTA with 3D image reconstructions, in long-term hemodialysis patients with dysfunctional arteriovenous fistulas and grafts (AVF and AVG). Material and Methods. During a 17-month period, 31 patients with dysfunctional AVF and AVG (24 AVF and seven AVG) were examined with MDCTA with 3D image postprocessing. Parameters such as comprehension of the anatomy, quality of contrast enhancement, and pathological vascular changes were measured. DSA was then performed in 24 patients. Results. MDCTA illustrated the anatomy of the AVF/AVG and the entire vascular tree to the heart, in a detailed and comprehensive manner in 93.5% of the evaluated segments, and depicted pathology of AVF/AVG or pathology of the associated vasculature. MDCTA demonstrated a total of 38 significant stenoses in 25 patients. DSA verified 37 stenoses in 24 patients and demonstrated two additional stenoses. MDCTA had thus a sensitivity of 95%. All 24 patients were treated with percutaneous transluminal angioplasty (PTA) with good technical results. Conclusion. MDCTA with 3D reconstructions of dysfunctioning AVFs and AVGs in hemodialysis patients is an accurate and reliable diagnostic method helping customize future intervention

Loop Quantization and Symmetry: Configuration Spaces

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Fleischhack, Christian

2018-06-01

Given two sets S 1, S 2 and unital C *-algebras A_1, A_2 of functions thereon, we show that a map {σ : {S}_1 \\longrightarrow {S}_2} can be lifted to a continuous map \\barσ : spec A_1 \\longrightarrow spec A_2 iff σ^\\ast A_2 := σ^\\ast f | f \\in A_2 \\subseteq A_1. Moreover, \\bar σ is unique if existing, and injective iff σ^\\ast A_2 is dense. Then, we apply these results to loop quantum gravity and loop quantum cosmology. For all usual technical conventions, we decide whether the cosmological quantum configuration space is embedded into the gravitational one; indeed, both are spectra of some C *-algebras, say, A_cosm and A_grav, respectively. Typically, there is no embedding, but one can always get an embedding by the defining A_cosm := C^\\ast(σ^\\ast A_grav), where {σ} denotes the embedding between the classical configuration spaces. Finally, we explicitly determine {C^\\ast(σ^\\ast A_grav) in the homogeneous isotropic case for A_grav generated by the matrix functions of parallel transports along analytic paths. The cosmological quantum configuration space so equals the disjoint union of R and the Bohr compactification of R, appropriately glued together.

Omega-3 Polyunsaturated Fatty Acid Supplementation to Prevent Arteriovenous Fistula and Graft Failure: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

Science.gov (United States)

Viecelli, Andrea K; Irish, Ashley B; Polkinghorne, Kevan R; Hawley, Carmel M; Johnson, David W; Mori, Trevor A; Pascoe, Elaine M; Strippoli, Giovanni F M; Lok, Charmaine E; Palmer, Suetonia C

2018-01-27

Arteriovenous access failure frequently occurs in people on hemodialysis and is associated with morbidity, mortality and large healthcare expenditures. Omega-3 polyunsaturated fatty acids (omega-3 PUFA) may improve access outcomes via pleiotropic effects on access maturation and function, but may cause bleeding complications. Systematic review with meta-analysis. Adults requiring hemodialysis via arteriovenous fistula or graft. Trials evaluating omega-3 PUFA for arteriovenous access outcomes identified by searches in CENTRAL, MEDLINE, and Embase to 24 January 2017. Omega-3 PUFA. Primary patency loss, dialysis suitability failure, access abandonment, interventions to maintain patency or assist maturation, bleeding, gastrointestinal side-effects, all-cause and cardiovascular mortality, hospitalization, and treatment adherence. Treatment effects were summarized as relative risks (RR) and 95% confidence intervals (CI). Evidence was assessed using GRADE. Five eligible trials (833 participants) with a median follow-up of 12 months compared peri-operative omega-3 PUFA supplementation with placebo. One trial (n=567) evaluated treatment for fistulae and four (n=266) for grafts. Omega-3 PUFA supplementation prevented primary patency loss with moderate certainty (761 participants, RR 0.81, CI 0.68-0.98). Low quality evidence suggested, that omega-3 PUFA may have had little or no effect on dialysis suitability failure (536 participants, RR 0.95, CI 0.73-1.23), access abandonment (732 participants, RR 0.78, CI 0.59-1.03), need for interventions (732 participants, RR 0.82, CI 0.64-1.04), or all-cause mortality (799 participants, RR 0.99, CI 0.51-1.92). Bleeding risk (793 participants, RR 1.40, CI 0.78-2.49) or gastrointestinal side-effects (816 participants, RR 1.22, CI 0.64-2.34) from treatment were uncertain. There was no evidence of different treatment effects for grafts and fistulae. Small number and methodological limitations of included trials. Omega-3 PUFA supplementation

Interventional recanalization of artificial arteriovenous fistula and graft for hemodialysis: angioplasty and pulsed-spray thrombolysis with Urokinase

International Nuclear Information System (INIS)

Shin, Sung Wook; Do, Young Soo; Park, Hong Seok and others

1998-01-01

To evaluate the effectiveness of percutaneous transluminal angioplasty (PTA) and pul-sed-spray pharmaco-mechanical thrombolysis (PSPMT) using urokinase for the management of insufficient hemodialysis access. Between September 1996 and May 1998, 21 insufficient hemodialysis accesses were treated in 16 patients(3 artificial arteriovenous fistulae, AVF; and 13 arteriovenous graft, AVG). PTA and PSPMT were performed in 6 and 15 cases, respectively, and success and long-term patency rates were evaluated. The overall success rate of PTA and PSPMT for insufficient hemodialysis access was 76. 2%(16/21). The success rates of PTA and PSPMT were 83.3%(5/6) and 73.3%(11/15), respectively. The primary patency rates of PSPMT were 69±12.8% at 6 months and 38±18.6% at 12 months. One of the two initially successful PTAs had been patent for 7 months, and the second PTA was performed at that time due to venous stenosis. The other was patent for 15 months throughout the follow-up period. PTA and PSPMT are effective primary methods for the treatment of insufficient hemodialysis access;success and patency rates were high, and the procedures can be performed repeatedly.=20

PTFE grafts versus tunneled cuffed catheters for hemodialysis: which is the second choice when arteriovenous fistula is not feasible?

Science.gov (United States)

Donati, Gabriele; Cianciolo, Giuseppe; Mauro, Raffaella; Rucci, Paola; Scrivo, Anna; Marchetti, Antonio; Giampalma, Emanuela; Golfieri, Rita; Panicali, Laura; Iorio, Mario; Stella, Andrea; La Manna, Gaetano; Stefoni, Sergio

2015-02-01

Vascular access-related complications are still one of the leading causes of morbidity in hemodialysis patients. The aim of this study was to compare polytetrafluoroethylene (PTFE) grafts versus tunneled cuffed permanent catheters (TCCs) in terms of vascular access and patients' survival. An observational study was carried out with a 2-year follow-up. Eighty-seven chronic hemodialysis patients were enrolled: 31 with a PTFE graft as vascular access for hemodialysis versus 56 with a TCC. Patients' mean age was 63.8 ± 14.6 (grafts) versus 73.5 ± 11.3 years (TCCs), P = 0.001. Significantly more patients with TCC had atrial fibrillation than patients with grafts (30.3% versus 6.5%, P = 0.01). In an unadjusted Kaplan-Meier analysis, median TCC survival at 24 months was 5.4 months longer than that of PTFE grafts but not significantly (log-rank test = 1.3, P = ns). In a Cox regression analysis adjusted for age, gender, number of previous vascular accesses, diabetes, atrial fibrillation, smoking, and any complication, this lack of significant difference in survival of the vascular access between TCC and PTFE groups was confirmed and diabetes proved to be an independent risk factor for the survival of both vascular accesses considered (P = 0.02). In an unadjusted Kaplan-Meier analysis, a higher mortality was found in the TCC group than in the PTFE group at 24 months (log-rank test = 10.07, P PTFE grafts. When an arteriovenous fistula (AVF) is not possible, PTFE grafts can be considered the vascular access of second choice, whereas TCCs can be used when an AVF or PTFE graft are not feasible or as a bridge to AVF or PTFE graft creation. Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Hemodynamic effects of spiral ePTFE prosthesis compared with standard arteriovenous graft in a carotid to jugular vein porcine model.

Science.gov (United States)

Jahrome, Ommid K; Hoefer, Imo; Houston, Graeme J; Stonebridge, Peter A; Blankestijn, Peter J; Moll, Frans L; de Borst, Gert J

2011-01-01

The primary patency rate of arteriovenous (AV) grafts is limited by distal venous anastomosis stenosis or occlusion due to intimal hyperplasia associated with distal graft turbulence. The normal blood flow in native arteries is spiral laminar flow. Standard vascular grafts do not produce spiral laminar flow at the distal anastomosis. Vascular grafts which induce a spiral laminar flow distally result in lower turbulence, particularly near the vessel wall. This initial study compares the hemodynamic effects of a spiral flow-inducing graft and a standard graft in a new AV carotid to jugular vein crossover graft porcine model. Four spiral flow grafts and 4 control grafts were implanted from the carotid artery to the contralateral jugular vein in 4 pigs. Two animals were terminated after 48 hours and 2 at 14 days. Graft patency was assessed by selective catheter digital angiography, and the flow pattern was assessed by intraoperative flow probe and color Doppler ultrasound (CDU) measurements. The spiral grafts were also assessed at enhanced flow rates using an external roller pump to simulate increased flow rates that may occur during dialysis using a standard dialysis needle cannulation. The method increased the flow rate through the graft by 660 ml/min. The graft distal anastomotic appearances were evaluated by explant histopathology. All grafts were patent at explantation with no complications. All anastomoses were found to be wide open and showed no significant angiographic stenosis at the distal anastomosis in both spiral and control grafts. CDU examinations showed a spiral flow pattern in the spiral graft and double helix pattern in the control graft. No gross histopathological effects were seen in either spiral or control grafts. This porcine model is robust and allows hemodynamic flow assessment up to 14 days postimplantation. The spiral flow-inducing grafts produced and maintained spiral flow at baseline and enhanced flow rates during dialysis needle

Assessment of Novel Anti-thrombotic Fusion Proteins for Inhibition of Stenosis in a Porcine Model of Arteriovenous Graft.

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Christi M Terry

Full Text Available Hemodialysis arteriovenous synthetic grafts (AVG provide high volumetric blood flow rates shortly after surgical placement. However, stenosis often develops at the vein-graft anastomosis contributing to thrombosis and early graft failure. Two novel fusion proteins, ANV-6L15 and TAP-ANV, inhibit the tissue factor/factor VIIa coagulation complex and the factor Xa/factor Va complex, respectively. Each inhibitor domain is fused to an annexin V domain that targets the inhibitor activity to sites of vascular injury to locally inhibit thrombosis. This study's objective was to determine if these antithrombotic proteins are safe and effective in inhibiting AVG stenosis.A bolus of either TAP-ANV or ANV-6L15 fusion protein was administered intravenously immediately prior to surgical placement of a synthetic graft between the external jugular vein and common carotid artery in a porcine model. At surgery, the vein and artery were irrigated with the anti-thrombotic fusion protein. Control animals received intravenous heparin. At 4 weeks, MRI was performed to evaluate graft patency, the pigs were then euthanized and grafts and attached vessels were explanted for histomorphometric assessment of neointimal hyperplasia at the vein-graft anastomosis. Blood was collected at surgery, immediately after surgery and at euthanasia for serum metabolic panels and coagulation chemistries.No acute thrombosis occurred in the control group or in either experimental group. No abnormal serum chemistries, activated clotting times or PT, PTT values were observed after treatment in experimental or control animals. However, at the vein-graft anastomosis, there was no difference between the control and experimental groups in cross-sectional lumen areas, as measured on MRI, and no difference in hyperplasia areas as determined by histomorphometry. These results suggest that local irrigation of TAP-ANV or ANV-6L15 intra-operatively was as effective in inhibiting acute graft thrombosis

Expanded polytetrafluoroethylene graft fistula for chronic hemodialysis.

Science.gov (United States)

Tellis, V A; Kohlberg, W I; Bhat, D J; Driscoll, B; Veith, F J

1979-01-01

In a retrospective study of 66 PTFE arteriovenous fistulae and 71 BCH arteriovenous fistulae for dialysis access, PTFE had a higher patency rate than BCH at 12 months (62.4 versus 32.5%). PTFE was easier to work with and easier to handle in the face of infection. The lateral upper arm approach to placement of the PTFE graft is desirable in patients who have had multiple previous access procedures because this area is usually free from scarring, is distant from neurovascular structures, and provides a greater length of graft for needle punctures.

Eco-efficiency and control loop configuration for recycle systems

Energy Technology Data Exchange (ETDEWEB)

Munir, Muhammad Tajammal; Yu, Wei; Young, Brent P. [The University of Auckland, Auckland (New Zealand)

2013-05-15

To integrate measurements of eco-efficiency with control loop configuration has become an important topic since all industrial processes/plants are requested to increase their eco-efficiency. The exergy eco-efficiency factor, a new measure of eco-efficiency for control loop configuration, has been developed recently. The exergy eco-efficiency factor is based on the thermodynamic concept of exergy, which can be used to analyze a process in terms of its efficiency. The combination of the relative gain array (RGA), NI, CN, dynamic RGA, and the exergy eco-efficiency factor will help guide the process designer to find the optimal control design with low operating cost/eco-efficiency. In this paper, we validate the proposed exergy eco-efficiency factor for processes with recycles which are very common industrially.

Eco-efficiency and control loop configuration for recycle systems

International Nuclear Information System (INIS)

Munir, Muhammad Tajammal; Yu, Wei; Young, Brent P.

2013-01-01

To integrate measurements of eco-efficiency with control loop configuration has become an important topic since all industrial processes/plants are requested to increase their eco-efficiency. The exergy eco-efficiency factor, a new measure of eco-efficiency for control loop configuration, has been developed recently. The exergy eco-efficiency factor is based on the thermodynamic concept of exergy, which can be used to analyze a process in terms of its efficiency. The combination of the relative gain array (RGA), NI, CN, dynamic RGA, and the exergy eco-efficiency factor will help guide the process designer to find the optimal control design with low operating cost/eco-efficiency. In this paper, we validate the proposed exergy eco-efficiency factor for processes with recycles which are very common industrially

A Mirnov loop array for field-reversed configurations

International Nuclear Information System (INIS)

Tuszewski, M.

1990-01-01

An array of 64 magnetic pick-up loops has been used for stability studies of large field-reversed configurations in the FRX-C/LSM device. This array proved reliable, could resolve signals of a few Gauss, and allowed the detection of several plasma instabilities. 3 refs., 4 figs

Straight configuration saphenous vein transposition to popliteal artery for vascular access.

Science.gov (United States)

Caco, Gentian; Golemi, Dhurata; Likaj, Eriola

2017-03-21

The saphenous vein is commonly used as a vascular graft in peripheral artery surgery but rarely used for vascular access. The literature on straight configuration saphenous vein transposition to the popliteal artery is scarce. Here we present two cases of straight configuration saphenous vein transposition to the popliteal artery for vascular access, the surgical technique and respective follow-up. Two young men, aged 29 and 36 years, were chosen for lower-limb vascular access for hemodialysis. The first patient was paraplegic since birth. He used his arms to move so upper extremity vascular access was avoided. The second patient presented with an infected upper extremity arteriovenous graft (AVG) and after multiple closed AVFs he had no more available arm veins. Both patients received autologous lower extremity straight configuration saphenous vein transpositions to the popliteal artery under spinal anesthesia in May and October 2012, respectively. Cannulation of the fistula was allowed after one month. There were no early complications. Slight swelling on the leg appeared in one of the patients. Both fistulas were still functional after 36 and 32 months, respectively. The straight configuration saphenous vein transposition to popliteal artery is simple to perform, offers a long and straight segment for cannulation and may be a suitable autologous vascular access in selected patients.

Radiation arteriopathy in the transgenic arteriovenous fistula model.

Science.gov (United States)

Lawton, Michael T; Arnold, Christine M; Kim, Yung J; Bogarin, Ernesto A; Stewart, Campbell L; Wulfstat, Amanda A; Derugin, Nikita; Deen, Dennis; Young, William L

2008-05-01

The transgenic arteriovenous fistula model, surgically constructed with transgenic mouse aorta interposed in common carotid artery-to-external jugular vein fistulae in nude rats, has a 4-month experimental window because patency and transgenic phenotype are lost over time. We adapted this model to investigate occlusive arteriopathy in brain arteriovenous malformations after radiosurgery by radiating grafted aorta before insertion in the fistula. We hypothesized that high-dose radiation would reproduce the arteriopathy observed clinically within the experimental time window and that deletions of endoglin (ENG) and endothelial nitric oxide synthase (eNOS) genes would modify the radiation response. Radiation arteriopathy in the common carotid arteries of 171 wild-type mice was examined with doses of 25, 80, 120, or 200 Gy (Experiment 1). Radiation arteriopathy in 68 wild-type arteriovenous fistulae was examined histologically and morphometrically with preoperative radiation doses of 0, 25, or 200 Gy (Experiment 2). Radiation arteriopathy in 51 transgenic arteriovenous fistulae (36 ENG and 15 eNOS knock-out fistulae) was examined using preoperative radiation doses of 0, 25, or 200 Gy (Experiment 3). High-dose radiation (200 Gy) of mouse common carotid arteries induced only mild arteriopathy (mean score, 0.66) without intimal hyperplasia and with high mortality (68%). Radiation arteriopathy in wild-type arteriovenous fistulae was severe (mean score, 3.5 at 200 Gy), with intimal hyperplasia and medial disruption at 3 months, decreasing luminal areas with increasing dose, and no mortality. Arteriopathy was robust in transgenic arteriovenous fistulae with ENG +/- and with eNOS +/-, with thick intimal hyperplasia in the former and distinct smooth muscle cell proliferation in the latter. The transgenic arteriovenous fistula model can be adapted to rapidly reproduce radiation arteriopathy observed in resected brain arteriovenous malformations after radiosurgery. High

Transseptal Guidewire Stabilization for Device Closure of a Large Pulmonary Arteriovenous Malformation

International Nuclear Information System (INIS)

Joseph, George; Kunwar, Brajesh Kumar

2013-01-01

A 46-year-old man presenting with massive hemoptysis was found to have a large pulmonary arteriovenous malformation (PAVM) in the right lung. Closure of the PAVM with an Amplatzer-type duct occluder was hampered by inability to advance the device delivery sheath into the PAVM due to vessel tortuosity and inadequate guidewire support. Atrial septal puncture was performed and a femorofemoral arteriovenous guidewire loop through the right pulmonary artery, PAVM, and left atrium was created. Traction on both ends of the guidewire loop allowed advancement of the device delivery sheath into the PAVM and successful completion of the procedure. Transseptal guidewire stabilization can be a valuable option during device closure of large PAVMs when advancement, stability, or kinking of the device delivery sheath is an issue.

Numerical evaluation of one-loop diagrams near exceptional momentum configurations

International Nuclear Information System (INIS)

Giele, Walter T.; Zanderighi, Giulia; Glover, E.W.N.

2004-01-01

One problem which plagues the numerical evaluation of one-loop Feynman diagrams using recursive integration by part relations is a numerical instability near exceptional momentum configurations. In this contribution we will discuss a generic solution to this problem. As an example we consider the case of forward light-by-light scattering

Magnetization configurations and hysteresis loops of small permalloy ellipses

International Nuclear Information System (INIS)

Schneider, M; Liszkowski, J; Rahm, M; Wegscheider, W; Weiss, D; Hoffmann, H; Zweck, J

2003-01-01

We investigated systematically the easy axis magnetization reversal of 20 nm thick permalloy ellipses with a fixed major axis of 1.47 μm and minor axes of 0.22-1.47 μm. Lorentz transmission electron microscopy was used to image the micromagnetic configurations during magnetization reversal. Hysteresis loops of single ellipses were recorded by means of micro-Hall magnetometry and could be traced back to certain reversal mechanisms observed by Lorentz microscopy. In most cases, the magnetization reversal is initiated by the evolution of a magnetization buckling, followed by the formation of a single, a double, or a trapped vortex configuration. For ellipses with high aspect ratio (length-to-width ratio), the magnetization switches in the reversed magnetic field without creation of a stable vortex configuration. Our experiments show that the characteristic field values for vortex creation, single vortex annihilation, and switching strongly depend on the shape anisotropy of the elements

Upper Extremity Steal Syndrome Is Associated with Atherosclerotic Burden and Access Configuration.

Science.gov (United States)

Kudlaty, Elizabeth A; Kendrick, Daniel E; Allemang, Matthew T; Kashyap, Vikram S; Wong, Virginia L

2016-08-01

Clinically significant steal syndrome occurs in a subset of dialysis patients with arteriovenous (AV) access. Factors associated with steal are poorly understood. Severe symptoms require access revision or sacrifice, potentially jeopardizing access options. Our objective was to review our dialysis access experience to identify factors associated with significant steal syndrome. We reviewed all adult patients undergoing their first permanent upper extremity access, AV fistula (AVF) or AV graft (AVG), between January 2008 and July 2011 at a single center. Medical, demographic, and access characteristics were collected from our electronic medical record and a local dialysis center's database. Patients who required correction of steal syndrome were compared with the larger access cohort. Statistical analysis included Fisher's exact test and χ(2) for noncontinuous variables and unpaired t-test for continuous variables. Of the 303 patients, 15 required correction for steal syndrome (8 of 232 AVF and 7 of 71 AVG). Eight were ligated; 2 were initially banded, then ligated; and 5 underwent distal revascularization with interval ligation. Coronary artery disease was more prevalent in steal syndrome patients (66.7% vs. 25%, P = 0.001); the same was found with peripheral arterial disease (40% vs. 13.8%, P = 0.02). Furthermore, more patients with steal syndrome were on clopidogrel for cardiovascular reasons (40% vs. 9%, P = 0.002). Steal syndrome only developed with AVF and AVG using brachial artery inflow. No cases of steal syndrome arose from radial/ulnar inflow (P = 0.03). All AVG with steal syndrome had a straight configuration; no looped AVG developed steal (P = 0.02). Other patient characteristics such as age, sex, race, hypertension, diabetes mellitus, congestive heart failure, cerebrovascular accident, cause of end-stage renal disease, and other medication history were not different between groups. Clinically significant steal syndrome is associated with

Suicide by severing the arterio-venous subclavian dialysis catheter.

Science.gov (United States)

Edirisinghe, P A S; Busuttil, A

2006-02-01

Haemodialysis access is an essential requirement for haemodialysis treatment in end-stage renal disease. The common forms are arteriovenous fistula (AVF) and arteriovenous grafts in ante-cubital fossa, forearm and upper thigh. Sometimes temporary or immediate access is created via a subclavian catheter or internal jugular catheter. This report is on a 79-year-old man who was suffering from chronic renal failure with a non-functional peripheral AVF; he was being dialysed through a permanent subclavian catheter and he became depressed due to continuing deterioration of his health. He used the easily accessible haemodialysis site as the method of suicide by cutting the tube that connected with the main vessel in his chest and bled to death. This highlights the requirement to assess carefully the patient's mental state in those on chronic haemodialysis, even though very few similar fatal cases have been previously reported.

Advanced Intermediate Heat Transport Loop Design Configurations for Hydrogen Production Using High Temperature Nuclear Reactors

International Nuclear Information System (INIS)

Chang Oh; Cliff Davis; Rober Barner; Paul Pickard

2005-01-01

The US Department of Energy is investigating the use of high-temperature nuclear reactors to produce hydrogen using either thermochemical cycles or high-temperature electrolysis. Although the hydrogen production processes are in an early stage of development, coupling either of these processes to the high-temperature reactor requires both efficient heat transfer and adequate separation of the facilities to assure that off-normal events in the production facility do not impact the nuclear power plant. An intermediate heat transport loop will be required to separate the operations and safety functions of the nuclear and hydrogen plants. A next generation high-temperature reactor could be envisioned as a single-purpose facility that produces hydrogen or a dual-purpose facility that produces hydrogen and electricity. Early plants, such as the proposed Next Generation Nuclear Plant (NGNP), may be dual-purpose facilities that demonstrate both hydrogen and efficient electrical generation. Later plants could be single-purpose facilities. At this stage of development, both single- and dual-purpose facilities need to be understood. A number of possible configurations for a system that transfers heat between the nuclear reactor and the hydrogen and/or electrical generation plants were identified. These configurations included both direct and indirect cycles for the production of electricity. Both helium and liquid salts were considered as the working fluid in the intermediate heat transport loop. Methods were developed to perform thermal-hydraulic evaluations and cycle-efficiency evaluations of the different configurations and coolants. The thermal-hydraulic evaluations estimated the sizes of various components in the intermediate heat transport loop for the different configurations. The relative sizes of components provide a relative indication of the capital cost associated with the various configurations. Estimates of the overall cycle efficiency of the various

Radiosurgery for brain arteriovenous malformations

International Nuclear Information System (INIS)

Latorzeff, I.; Schlienger, M.; Sabatier, J.; Borius, P.Y.; Lotterie, J.A.; Bourdin, S.; Menegalli, D.; Cognard, C.; Januel, A.C.; Desal, H.; Debono, B.; Blond, S.

2012-01-01

Radiosurgery as treatment for arteriovenous malformations has shown a good efficacy in reducing intracranial bleeding due to rupture. The choice of therapeutic modalities is based on evolutive risk and arteriovenous malformations volume, patient profile and risks stratification following therapeutic techniques (microsurgery, radiosurgery, embolization). Nidus size, arteriovenous malformations anatomical localization, prior embolization or bleeding, distributed dose are predictive factors for radio-surgery's good results and tolerance. This review article will highlight arteriovenous malformations radiosurgery indications and discuss recent irradiation alternatives for large arteriovenous malformation volumes. (authors)

Loop-driven graphical unitary group approach to the electron correlation problem, including configuration interaction energy gradients

International Nuclear Information System (INIS)

Brooks, B.R.

1979-09-01

The Graphical Unitary Group Approach (GUGA) was cast into an extraordinarily powerful form by restructuring the Hamiltonian in terms of loop types. This restructuring allows the adoption of the loop-driven formulation which illuminates vast numbers of previously unappreciated relationships between otherwise distinct Hamiltonian matrix elements. The theoretical/methodological contributions made here include the development of the loop-driven formula generation algorithm, a solution of the upper walk problem used to develop a loop breakdown algorithm, the restriction of configuration space employed to the multireference interacting space, and the restructuring of the Hamiltonian in terms of loop types. Several other developments are presented and discussed. Among these developments are the use of new segment coefficients, improvements in the loop-driven algorithm, implicit generation of loops wholly within the external space adapted within the framework of the loop-driven methodology, and comparisons of the diagonalization tape method to the direct method. It is also shown how it is possible to implement the GUGA method without the time-consuming full (m 5 ) four-index transformation. A particularly promising new direction presented here involves the use of the GUGA methodology to obtain one-electron and two-electron density matrices. Once these are known, analytical gradients (first derivatives) of the CI potential energy are easily obtained. Several test calculations are examined in detail to illustrate the unique features of the method. Also included is a calculation on the asymmetric 2 1 A' state of SO 2 with 23,613 configurations to demonstrate methods for the diagonalization of very large matrices on a minicomputer. 6 figures, 6 tables

A Novel Attempt to Standardize Results of CFD Simulations Basing on Spatial Configuration of Aortic Stent-Grafts.

Directory of Open Access Journals (Sweden)

Andrzej Polanczyk

Full Text Available Currently, studies connected with Computational Fluid Dynamic (CFD techniques focus on assessing hemodynamic of blood flow in vessels in different conditions e.g. after stent-graft's placement. The paper propose a novel method of standardization of results obtained from calculations of stent-grafts' "pushing forces" (cumulative WSS--Wall Shear Stress, and describes its usefulness in diagnostic process. AngioCT data from 27 patients were used to reconstruct 3D geometries of stent-grafts which next were used to create respective reference cylinders. We made an assumption that both the side surface and the height of a stent-graft and a reference cylinder were equal. The proposed algorithm in conjunction with a stent-graft "pushing forces" on an implant wall, allowed us to determine which spatial configuration of a stent-graft predispose to the higher risk of its migration. For stent-grafts close to cylindrical shape (shape factor φ close to 1 WSS value was about 267 Pa, while for stent-grafts different from cylindrical shape (φ close to 2 WSS value was about 635 Pa. It was also noticed that deformation in the stent-graft's bifurcation part impaired blood flow hemodynamic. Concluding the proposed algorithm of standardization proved its usefulness in estimating the WSS values that may be useful in diagnostic process. Angular bends or tortuosity in bifurcations of an aortic implant should be considered in further studies of estimation of the risk of implantation failure.

Outcomes of AV Fistulas and AV Grafts after Interventional Stent-Graft Deployment in Haemodialysis Patients

Energy Technology Data Exchange (ETDEWEB)

Schmelter, Christopher, E-mail: christopher.schmelter@klinikum-ingolstadt.de; Raab, Udo, E-mail: udo.raab@klinikum-ingolstadt.de [Klinikum Ingolstadt, Department of Diagnostic and Interventional Radiology (Germany); Lazarus, Friedrich, E-mail: friedrich.lazarus@klinikum-ingolstadt.de [Klinikum Ingolstadt, Department of Nephrology (Germany); Ruppert, Volker, E-mail: volker.ruppert@klinikum-ingolstadt.de [Klinikum Ingolstadt, Department of Vascular Surgery (Germany); Vorwerk, Dierk, E-mail: dierk.vorwerk@klinikum-ingolstadt.de [Klinikum Ingolstadt, Department of Diagnostic and Interventional Radiology (Germany)

2015-08-15

PurposeThe study was designed to assess outcomes of arteriovenous (AV) accesses after interventional stent-graft deployment in haemodialysis patients.Materials and Methods63 haemodialysis patients with 66 AV fistulas and AV grafts were treated by interventional stent-graft deployment from 2006 to 2012 at our hospital. Data of these patients were retrospectively analysed for location of deployed stent-grafts, occurrence and location of (re-)stenosis and (re-)thrombosis. Complex stenosis was the most frequent indication for stent-graft deployment (45.5 %), followed by complications of angioplasty with vessel rupture or dissection (31.8 %).ResultsA high rate of procedural success was achieved (98.5 %). The most frequent location of the deployed stent-graft was the draining vein (66.7 %). Stent-graft deployment was more frequent in AV grafts than in AV fistulas. Primary patency was 45.5 % at 6 month, 31.3 % at 12 month and 19.2 % at 24 month. Primary patency was significantly better for AV fistulas than for AV grafts with deployed stent-grafts. Patency of the deployed stent-graft was much better than overall AV access primary patency with deployed stent-graft. Re-stenosis with thrombosis was the most frequent indication for re-intervention. Most frequent location of re-stenosis was the draining vein (37.1 %), followed by stenosis at the AV access (29.5 %) and the deployed stent-graft (23.5 %).ConclusionRe-stenosis and re-thrombosis remain frequent in AV fistulas and AV grafts in haemodialysis patients despite stent-graft deployment. Re-stenosis of the deployed stent-graft is, only in the minority of the cases, responsible for AV access dysfunction.

Successful endovascular treatment of a hemodialysis graft pseudoaneurysm by covered stent and direct percutaneous thrombin injection.

LENUS (Irish Health Repository)

Keeling, Aoife N

2011-07-25

Vascular access for hemodialysis remains a challenge for nephrologists, vascular surgeons, and interventional radiologists alike. Arteriovenous fistula and synthetic grafts remain the access of choice for long-term hemodialysis; however, they are subject to complications from infection and repeated needle cannulation. Pseudoaneurysms are an increasingly recognized adverse event. At present, there are many minimally invasive methods to repair these wall defects. We present a graft pseudoaneurysm, which required a combination of endovascular stent graft placement and percutaneous thrombin injection for successful occlusion.

Wavelength conversion by use of four-wave mixing in a novel optical loop configuration

DEFF Research Database (Denmark)

Yu, Jianjun; Jeppesen, Palle

2000-01-01

and the signal waves. By use of the novel loop configuration, nonreturn-to-zero wavelength conversion at 10 Gbits/s is achieved. The FWM-to-pump ratio, the FWM-to-signal ratio, and the signal-to-noise ratio are improved by 17.9, 18.8, and 8.2 dB, respectively. A principle experiment of wavelength conversion...

Redoable Tie-Over Dressing Using Multiple Loop Silk Threads

Directory of Open Access Journals (Sweden)

Hyeon Jong Jo

2013-05-01

Full Text Available After skin grafting, to prevent hematoma or seroma collection at the graft site, a tie-over dressing has been commonly used. However, although the conventional tie-over dressing by suture is a useful method for securing a graft site, refixation is difficult when repeated tie-over dressing is needed. Therefore, we recommend a redoable tie-over dressing technique with multiple loops threads and connecting silk threads. After the raw surface of each of our cases was covered with a skin graft, multiple loop silk thread attached with nylon at the skin graft margin. We applied the ointment gauze and wet cotton/fluffy gauze over the skin graft, then fixed the dressing by connecting cross-counter multiple loop thread with connecting silk threads. When we opened the tie-over dressing by cutting the connecting silk threads, we repeated the tie-over dressing with the same method. The skin graft was taken successfully without hematoma or seroma collection or any other complications. In conclusion, we report a novel tie-over dressing enabling simple fixation of the dressing to maintain proper tension for wounds that require repetitive fixation. Further, with this reliable method, the skin grafts were well taken.

Redoable Tie-Over Dressing Using Multiple Loop Silk Threads

Directory of Open Access Journals (Sweden)

Hyeon Jong Jo

2013-05-01

Full Text Available After skin grafting, to prevent hematoma or seroma collection at the graft site, a tie-over dressing has been commonly used. However, although the conventional tie-over dressing by suture is a useful method for securing a graft site, refixation is difficult when repeated tieover dressing is needed. Therefore, we recommend a redoable tie-over dressing technique with multiple loops threads and connecting silk threads. After the raw surface of each of our cases was covered with a skin graft, multiple loop silk thread attached with nylon at the skin graft margin. We applied the ointment gauze and wet cotton/fluffy gauze over the skin graft, then fixed the dressing by connecting cross-counter multiple loop thread with connecting silk threads. When we opened the tie-over dressing by cutting the connecting silk threads, we repeated the tie-over dressing with the same method. The skin graft was taken successfully without hematoma or seroma collection or any other complications. In conclusion, we report a novel tie-over dressing enabling simple fixation of the dressing to maintain proper tension for wounds that require repetitive fixation. Further, with this reliable method, the skin grafts were well taken.

Independent SU(2)-loop variables and the reduced configuration space of SU(2)-lattice gauge theory

International Nuclear Information System (INIS)

Loll, R.

1992-01-01

We give a reduction procedure for SU(2)-trace variables and an explicit description of the reduced configuration sace of pure SU(2)-gauge theory on the hypercubic lattices in two, three and four dimensions, using an independent subset of the gauge-invariant Wilson loops. (orig.)

Study of vortex configurations in Yb3Rh4Sn13 via minor hysteresis loops

International Nuclear Information System (INIS)

Sarkar, S.; Tulapurkar, A.A.; Ramakrishnan, S.; Grover, A.K.; Tomy, C.V.

2001-01-01

The tracings of the minor hysteresis loops in the superconductor Yb 3 Rh 4 Sn 13 (i) elucidate the path dependence in J c (H), (ii) help to reach the stable vortex configuration from a given metastable state and (iii) reveal the occurrence of step change in equilibrium magnetization across the peak effect (PE) regime. (author)

Haemodynamics in axillobifemoral bypass grafts

NARCIS (Netherlands)

C.H. Wittens

1992-01-01

textabstractThis thesis is based on four publications on the subject of graft configuration and haemodynamics in axillobifemoral bypass grafts: 1. A clinical evaluation of 17 patients with axillobifemoral bypass graft operations, performed for various indications. Two important observations were

Suppressing unsteady flow in arterio-venous fistulae

Science.gov (United States)

Grechy, L.; Iori, F.; Corbett, R. W.; Shurey, S.; Gedroyc, W.; Duncan, N.; Caro, C. G.; Vincent, P. E.

2017-10-01

Arterio-Venous Fistulae (AVF) are regarded as the "gold standard" method of vascular access for patients with end-stage renal disease who require haemodialysis. However, a large proportion of AVF do not mature, and hence fail, as a result of various pathologies such as Intimal Hyperplasia (IH). Unphysiological flow patterns, including high-frequency flow unsteadiness, associated with the unnatural and often complex geometries of AVF are believed to be implicated in the development of IH. In the present study, we employ a Mesh Adaptive Direct Search optimisation framework, computational fluid dynamics simulations, and a new cost function to design a novel non-planar AVF configuration that can suppress high-frequency unsteady flow. A prototype device for holding an AVF in the optimal configuration is then fabricated, and proof-of-concept is demonstrated in a porcine model. Results constitute the first use of numerical optimisation to design a device for suppressing potentially pathological high-frequency flow unsteadiness in AVF.

Lower limb gigantism, lymphedema, and painful varicosities following a thigh vascular access graft.

Science.gov (United States)

Thompson, Michael; Mathuram Thiyagarajan, Umasankar; Akoh, Jacob A

2014-07-01

Prosthetic arteriovenous grafts (AVGs) are associated with greater morbidity than autogenous arteriovenous fistulas (AVFs), but their use is indicated when AVF formation is not possible. This report adds to the literature a case of lower limb gigantism, painful varicosities, and lymphedema following long-term use of AVG in the upper thigh. The patient's past medical history included renal transplantation on the same side well before the AVG was inserted and right leg deep vein thrombosis. Suspicion of AVG thrombosis was excluded by Doppler ultrasound, which demonstrated an access flow of 1700 mL/min. A computed tomography (CT) scan of the abdomen and pelvis did not identify the cause of her symptoms. Whereas functional incompetence of the iliac vein valve might be responsible for the varicosities, the extent of hypertrophy in this case raises the suspicion of lymphatic blockage possibly secondary to groin dissection undertaken at the time of graft insertion, in addition to the previous dissection at the time of transplantation. This case highlights the need for minimal groin dissection during AVG insertion, particularly in patients with a history of previous abdominopelvic surgery. © 2014 International Society for Hemodialysis.

Arteriovenous Malformations

Science.gov (United States)

Arteriovenous malformations (AVMs) are defects in your vascular system. The vascular system includes arteries, veins, and capillaries. Arteries carry blood away from the heart to other organs; veins carry blood back to the heart. Capillaries connect the arteries and veins. An ...

Cardiac Arrest Secondary to Bilateral Pulmonary Emboli following Arteriovenous Fistula Thrombectomy: A Case Report with Review of the Literature

Directory of Open Access Journals (Sweden)

Avni Shah

2012-01-01

Full Text Available Number of patients with End Stage Renal Disease (ESRD is growing worldwide. Hemodialysis remains the main modality of renal replacement therapy for ESRD patients. A patent hemodialysis access (arteriovenous fistula or arteriovenous graft plays a key role in successful delivery of hemodialysis. Common vascular access issues encountered by patients and nephrologists are thrombosis and infection. The thrombosed access is declotted by various percutaneous techniques these days by multiple outpatient access centers in a timely fashion. Thrombolysis can give rise to various complications, a few of which can be life threatening. A young hemodialysis patient underwent percutaneous thrombolysis of his clotted arteriovenous fistula. Outpatient access thrombectomy was complicated immediately afterwards with cardiac arrest requiring cardiac resuscitation in the recovery room. The patient was admitted to intensive care unit after life sustaining care. Work up revealed multiple pulmonary emboli to both lung fields on CT scan of the chest. Patient was anticoagulated and discharged from the hospital. Thrombolysis of clotted hemodialysis access is associated commonly with occurrences of pulmonary embolic which are usually asymptomatic. Massive pulmonary embolization due to access thrombolysis is rare. Nephrologists and radiologists should be aware of this dangerous complication particularly in patients with preexisting cardiopulmonary disease.

Pulmonary arteriovenous fistulas

International Nuclear Information System (INIS)

Medeiros Sobrinho, J.H. de; Kambara, A.M.

1987-01-01

Six cases of pulmonary arteriovenous fistulas, isolated, without hemorrhagic hereditary telangiectasia (Rendu-Osler-Weber Symdrome) are reported emphasizing the radiographic, tomographic and angiographic examinations, (M.A.C.) [pt

Coronary Arteriovenous Fistula Causing Hydrops Fetalis

Directory of Open Access Journals (Sweden)

Nilüfer Çetiner

2014-01-01

Full Text Available Fetal heart failure and hydrops fetalis may occur due to systemic arteriovenous fistula because of increased cardiac output. Arteriovenous fistula of the central nervous system, liver, bone or vascular tumors such as sacrococcygeal teratoma were previously reported to be causes of intrauterine heart failure. However, coronary arteriovenous fistula was not reported as a cause of fetal heart failure previously. It is a rare pathology comprising 0.2–0.4% of all congenital heart diseases even during postnatal life. Some may remain asymptomatic for many years and diagnosed by auscultation of a continuous murmur during a routine examination, while a larger fistulous coronary artery opening to a low pressure cardiac chamber may cause ischemia of the affected myocardial region due to steal phenomenon and may present with cardiomyopathy or congestive heart failure during childhood. We herein report a neonate with coronary arteriovenous fistula between the left main coronary artery and the right ventricular apex, who presented with hydrops fetalis during the third trimester of pregnancy.

Evaluation of the degree of arteriovenous shunting in intracranial arteriovenous malformations using pseudo-continuous arterial spin labeling magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Sunwoo, Leonard; Park, Sun-Won [Seoul Metropolitan Government - Seoul National University Boramae Medical Center, Department of Radiology, Seoul (Korea, Republic of); Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Sohn, Chul-Ho; Yun, Tae Jin; Choi, Seung Hong; Cho, Young Dae; Kim, Ji-hoon; Han, Moon Hee [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Hospital, Department of Radiology, Seoul (Korea, Republic of); Lee, Jong Young [Kangdong Sacred Heart Hospital, Department of Neurosurgery, Seoul (Korea, Republic of); Yi, Kyung Sik [Chungbuk National University Hospital, Department of Radiology, Cheongju (Korea, Republic of); Paek, Sun Ha; Kim, Yong Hwy; Kim, Jin Wook; Chung, Hyun-Tai; Kim, Dong Gyu [Seoul National University Hospital, Department of Neurosurgery, Seoul (Korea, Republic of)

2015-08-15

Intracranial arteriovenous malformations (AVMs) display venous signals on arterial spin labeling (ASL) magnetic resonance (MR) imaging due to the presence of arteriovenous shunting. Our aim was to quantitatively correlate AVM signal intensity on ASL with the degree of arteriovenous shunting estimated on digital subtraction angiography (DSA) in AVMs. MR imaging including pseudo-continuous ASL at 3 T and DSA were obtained on the same day in 40 patients with intracranial AVMs. Two reviewers assessed the nidus and venous signal intensities on ASL images to determine the presence of arteriovenous shunting. Interobserver agreement on ASL between the reviewers was determined. ASL signal intensity of the AVM lesion was correlated with AVM size and the time difference between normal and AVM venous transit times measured from the DSA images. Interobserver agreement between two reviewers for nidus and venous signal intensities was excellent (κ = 0.80 and 1.0, respectively). Interobserver agreement regarding the presence of arteriovenous shunting was perfect (κ = 1.0). AVM signal intensity showed a positive relationship with the time difference between normal and AVM venous transit times (r = 0.638, P < 0.001). AVM signal intensity also demonstrated a positive relationship with AVM size (r = 0.561, P < 0.001). AVM signal intensity on ASL in patients with AVM correlates well with the degree of early vein opacification on DSA, which corresponds to the degree of arteriovenous shunting. (orig.)

Oscillation damping of chiral string loops

International Nuclear Information System (INIS)

Babichev, Eugeny; Dokuchaev, Vyacheslav

2002-01-01

Chiral cosmic string loops tend to the stationary (vorton) configuration due to energy loss into gravitational and electromagnetic radiation. We describe the asymptotic behavior of near stationary chiral loops and their fading to vortons. General limits on the gravitational and electromagnetic energy losses by near stationary chiral loops are found. For these loops we estimate the oscillation damping time. We present solvable examples of gravitational radiation energy loss by some chiral loop configurations. The analytical dependence of string energy with time is found in the case of the chiral ring with small amplitude radial oscillations

Genetics Home Reference: capillary malformation-arteriovenous malformation syndrome

Science.gov (United States)

... Institute: How the Heart Works National Institute of Neurological Disorders and Stroke: Arteriovenous Malformation Educational Resources (7 links) Boston Children's Hospital: Arteriovenous Malformation Boston Children's Hospital: Capillary Malformation ...

Exercise-induced arteriovenous intrapulmonary shunting in dogs.

Science.gov (United States)

Stickland, Michael K; Lovering, Andrew T; Eldridge, Marlowe W

2007-08-01

We have previously shown, using contrast echocardiography, that intrapulmonary arteriovenous pathways are inducible in healthy humans during exercise; however, this technique does not allow for determination of arteriovenous vessel size or shunt magnitude. The purpose of this study was to determine whether large-diameter (more than 25 microm) intrapulmonary arteriovenous pathways are present in the dog, and whether exercise recruits these conduits. Through the right forelimb, 10.8 million 25-microm stable isotope-labeled microspheres (BioPAL, Inc., Worcester, MA) were injected either at rest (n = 8) or during high-intensity exercise (6- 8 mph, 10-15% grade, n = 6). Systemic arterial blood was continuously sampled during and for 3 minutes after injection. After euthanasia, tissue samples were obtained from the heart, liver, kidney, and skeletal muscle. In addition, 25- and 50-microm microspheres were infused into four isolated dog lungs that were ventilated and perfused at constant pressures similar to exercise. Blood and tissue samples were commercially analyzed for the presence of microspheres. No microspheres were detected in the arterial blood or tissue samples from resting dogs. In contrast, five of six exercising dogs showed evidence of exercise-induced intrapulmonary arteriovenous shunting, as microspheres were detected in arterial blood and/or tissue. Furthermore, shunt magnitude was calculated to be 1.4 +/- 0.8% of cardiac output (n = 3). Evidence of intrapulmonary arteriovenous anastomoses was also found in three of four isolated lungs. Consistent with previous human findings, these data demonstrate that intrapulmonary arteriovenous pathways are functional in the dog and are recruited with exercise.

Traumatic Intrarenal Arteriovenous Fistula Treated by Conservative ...

African Journals Online (AJOL)

1974-06-01

Jun 1, 1974 ... with these vascular lesions.' Varela' in 1928 reported the first case of intrarenal arteriovenous fistula. Arteriovenous fistula of the kidney is an ... and penetrating abdominal trauma, this lesion will be encountered with increasing frequency. Selective renal artery catheterisation aids materially in making the.

Prefabrication of a vascularized nerve graft by vessel implantation: preliminary report of an experimental model.

Science.gov (United States)

Cavadas, P C; Vera-Sempere, F J

1994-01-01

Regeneration through vascularized nerve grafts (VNG) seems to be better than nonvascularized nerve grafts (NVNG), especially in hostile beds. We report on an experimental technique of prefabrication of VNG by direct vessel implantation. An arteriovenous fistula was created in the groin region with autologous vein grafts in the Wistar rat model, and implanted into the sciatic nerve. Five weeks later the sciatic VNG was elevated on the prefabricated pedicle. The flap was free-transferred orthotopically over a silicone sheet to impede plasmatic imbibition. Flap viability at 3 days was complete. India ink injection of the AV fistula resulted in capillary ink filling within the nerve and surrounding tissues. Histologic sections of the flap were examined, revealing its neovascularity. In an ongoing study, the regeneration through this prefabricated VNG is being compared to native VNG.

Arteriovenous malformation of the mandible

International Nuclear Information System (INIS)

Kim, Dong Youn; Lee, Kang Sook; Choi, Karp Shik

1995-01-01

The arteriovenous malformation, an uncommon lesion, is a direct communication between an artery and a vein that bypasses the intervening capillary bed. The authors experienced two cases of arteriovenous malformation in 17-year-old and 18-year-old female patients who had suffered from mandibular pain and gingival bleeding. As a result of careful analysis of clinical and angiographic radiological examinations, we diagnosed them as arteriovenous malformations. The following result were obtained; 1. Main clinical symptoms were dull pain and gingival bleeding on the mandibular body area and redness, pain on palpitation in the lesional sites were also observed. 2. Radiographically, well-defined radiolucent lesions with multiple osteolytic defects were observed. In radionuclide scan, increased uptakes of radioisotope were observed in the lesional sites. 3. Increased venous shunt supplied by the facial, lingual and inferior alveolar arteries was observed in angiography. After embolotherapy was performed, no recurrence was reported during 3 to 6 months follow up.

Spectroscopic Investigation of the Canopy Configurations in Nanoparticle Organic Hybrid Materials of Various Grafting Densities during CO 2 Capture

KAUST Repository

Petit, Camille; Park, Youngjune; Lin, Kun-Yi Andrew; Park, Ah-Hyung Alissa

2012-01-01

Novel liquid-like nanoparticle organic hybrid materials (NOHMs) made of polyetheramine chains tethered onto functionalized silica nanoparticles were synthesized and characterized before and after exposure to CO 2 using NMR, Raman, and ATR FT-IR spectroscopies in order to investigate the effect of the grafting densities on the NOHM canopy structure. Considering the promising tunable properties for CO 2 capture of NOHMs, this study was conducted to provide important structural information to better design NOHMs for CO 2 capture. In order to minimize the CO 2 absorption via enthalpic effect and provide a more accurate assessment of the structural effects, the NOHMs were synthesized without task-specific groups. A greater chain ordering and decreased intermolecular interactions were observed in NOHMs compared to the unbound polymer. This was attributed to the specific structural arrangement of the frustrated canopy. The distinct configuration of grafted polymer chains caused different CO 2 packing and CO 2-induced swelling behaviors between the NOHMs and the unbound polymer. The grafting density influenced the ordering and coupling of the polymer chains and CO 2-induced swelling. Its effect on the CO 2 packing behavior was less pronounced. © 2011 American Chemical Society.

Spectroscopic Investigation of the Canopy Configurations in Nanoparticle Organic Hybrid Materials of Various Grafting Densities during CO 2 Capture

KAUST Repository

Petit, Camille

2012-01-12

Novel liquid-like nanoparticle organic hybrid materials (NOHMs) made of polyetheramine chains tethered onto functionalized silica nanoparticles were synthesized and characterized before and after exposure to CO 2 using NMR, Raman, and ATR FT-IR spectroscopies in order to investigate the effect of the grafting densities on the NOHM canopy structure. Considering the promising tunable properties for CO 2 capture of NOHMs, this study was conducted to provide important structural information to better design NOHMs for CO 2 capture. In order to minimize the CO 2 absorption via enthalpic effect and provide a more accurate assessment of the structural effects, the NOHMs were synthesized without task-specific groups. A greater chain ordering and decreased intermolecular interactions were observed in NOHMs compared to the unbound polymer. This was attributed to the specific structural arrangement of the frustrated canopy. The distinct configuration of grafted polymer chains caused different CO 2 packing and CO 2-induced swelling behaviors between the NOHMs and the unbound polymer. The grafting density influenced the ordering and coupling of the polymer chains and CO 2-induced swelling. Its effect on the CO 2 packing behavior was less pronounced. © 2011 American Chemical Society.

[Multiple coronary arteriovenous fistulae. Hazard or predetermination?].

Science.gov (United States)

Rangel, Alberto; Muñoz-Castellanos, Luis; Solorio, Sergio

2003-01-01

The authors present the clinical cases of three adult patients (49, 53 and 61 year-old), with rheumatic cardiac valvulopathy, and bilateral coronary arteriovenous fistulae draining in the main pulmonary artery. Based on documental investigation, the authors speculate about the predeterminate origin of coronary arteriovenous fistulae. At first glance, it seems obvious that congenital cardiopathies occur at random, i.e., embryonic development deviate or stops due to unknown reasons, originating the persistence of lacunar blood spaces prior to the development of coronary arteries cords. There are two factors involved in the genesis of congenital malformations: a genomic preexisting factor and the presence of an environmental precipitating factor, i.e., isolated pulmonary valve atresia or left ventricular hypoplastic syndrome, with mitral and aortic valve stenosis, can predispose development of coronary arteriovenous fistulae. Recently, the question has been raised whether there is a relation of coronary arteries fistulae with: ethnic groups, hereditary gigantism, autoimmune diseases, such as polymyositis, hereditary hemorrhagic telangiectasia, and apical hypertrophic myocardiopathy. Coronary arteriovenous fistulae, as well as some congenital cardiopathies, could be due to chromosome alterations or might be related to hereditary diseases, such as hemorrhagic telangiectasia, induced by a disturbed genetic program. Although, there is no concrete evidence that a genetic factor is related to the development of coronary arteriovenous fistulae, there are signs that suggest that such a possibility could be investigated.

Splenic arteriovenous fistula treated with percutaneous transarterial embolization

DEFF Research Database (Denmark)

Madsen, M.A.; Frevert, S.; Madsen, P.L.

2008-01-01

Splenic arteriovenous fistula is a rare complication following splenectomy. We report a case of a large splenic arteriovenous fistula 23 years after splenectomy in a 50-year old male with abdominal pain, gastro-intestinal bleeding, ascites, diarrhoea, dyspnoea, portal hypertension and heart failure...

Rendu-Osler-Weber syndrome presenting with pulmonary arteriovenous fistula

International Nuclear Information System (INIS)

Halefoglu, A.M.

2005-01-01

A pulmonary arteriovenous fistula is an abnormal connection between pulmonary arteries and veins. Patients with Rendu-Osler-Weber syndrome may present with this vascular malformation, which is a typical finding of the disease. Approximately 5-15% of Rendu-Osler-Weber syndrome patients have pulmonary arteriovenous malformations (AVM) and there is usually a family history of AVM in these patients. The malformations are usually located in the lower lobes. In this paper, I describe a 49-year-old male patient with dyspnoea, cough, haemoptysis and epistaxis. Physical examination showed nasal telangiectasias, cyanosis of the lips and nails, and a systolic bruit over the left lung. Chest X-ray revealed a 5-cm mass in the left lower lobe and after magnetic resonance examination, together with 3-D magnetic resonance angiography, it was demonstrated to be a pulmonary arteriovenous fistula. The history of a niece with a similar history of suspected pulmonary arteriovenous fistula led me to consider the possibility of Rendu-Osler-Weber syndrome presenting with a pulmonary arteriovenous fistula. Copyright (2005) Blackwell Science Pty Ltd

Maturation of arteriovenous fistula: Analysis of key factors

Directory of Open Access Journals (Sweden)

Muhammad A. Siddiqui

2017-12-01

Full Text Available The growing proportion of individuals suffering from chronic kidney disease has considerable repercussions for both kidney specialists and primary care. Progressive and permanent renal failure is most frequently treated with hemodialysis. The efficiency of hemodialysis treatment relies on the functional status of vascular access. Determining the type of vascular access has prime significance for maximizing successful maturation of a fistula and avoiding surgical revision. Despite the frequency of arteriovenous fistula procedures, there are no consistent criteria applied before creation of arteriovenous fistulae. Increased prevalence and use of arteriovenous fistulae would result if there were reliable criteria to assess which arteriovenous fistulae are more likely to reach maturity without additional procedures. Published studies assessing the predictive markers of fistula maturation vary to a great extent with regard to definitions, design, study size, patient sample, and clinical factors. As a result, surgeons and specialists must decide which possible risk factors are most likely to occur, as well as which parameters to employ when evaluating the success rate of fistula development in patients awaiting the creation of permanent access. The purpose of this literature review is to discuss the role of patient factors and blood markers in the development of arteriovenous fistulae.

Arteriovenous Malformation of the Pancreas

Directory of Open Access Journals (Sweden)

Alexandros Charalabopoulos

2011-01-01

Full Text Available Pancreatic arteriovenous malformation (PAVM is a very rare and mostly congenital lesion, with less than 80 cases described in the English-published literature. It is defined as a tumorous vascular abnormality that is constructed between an anomalous bypass anastomosis of the arterial and venous networks within the pancreas. It represents about 5% of all arteriovenous malformations found in the gastrointestinal tract. Herein, we present a 64-year-old patient with symptomatic PAVM involving the body and tail of the organ, which was successfully treated by transcatheter arterial embolization. The disease spectrum and review of the literature are also presented.

Surgical Treatment for a Complex Congenital Arteriovenous Malformation of the Lower Limb

OpenAIRE

Ozcan, Ali Vefa; Boysan, Emre; Isikli, Osman Yasar; Goksin, Ibrahim

2013-01-01

Arteriovenous fistula is defined as an abnormal communication between the arterial and venous systems. The complexity of congenital arteriovenous malformations makes treatment challenging. We present the case of a 23-year-old woman who had a complex congenital arteriovenous malformation in her left leg and a history of 2 unsuccessful coil-embolization procedures. We ligated all the feeding arteries of the arteriovenous malformation in the region of the superficial femoral artery, and the surg...

Renal arteriovenous shunts, fistulae and malformations - angiographic case reports

International Nuclear Information System (INIS)

Esser, P.W.; Duex, A.

1989-01-01

Individual case reports serve to demonstrate the pathogenetically different renal arteriovenous shunt formations, such as congenital arteriovenous angioma, spontaneous arteriovenous aneurysm, iatrogenic arterio-venous fistula and neoplasia-conditioned arteriovenous fistula. These are discussed in detail, including treatment possibilities. The ranking of digital subtraction angiography is emphasised. Our case reports show that in preoperative diagnosis of pathological structures in the kidney, renovasography is an invaluable tool, especially with i.a. DSA technique, and is superior to all other methods such as sonography, CT, MR and colour-coded Doppler sonography. Due to improved techniques of angiography (markedly lower amounts of contrast medium when using catheters of narrow lumen) indication for i.a. DSA in haematuria of unknown origin should be liberal. Above all, the method should be performed at an early stage. If there is a NAD renal finding in the i.a. DSA renovasogram in renally conditioned haematuria even when using a 1024 x 1024 image matrix, it is advisable to perform selective renal arteriography to either exclude or confirm the existence of an intrarenal angioma, additionally in conventional sheet film technique because of the superior power of resolution. (orig.) [de

Computational fluid dynamic evaluation of the side-to-side anastomosis for arteriovenous fistula.

Science.gov (United States)

Hull, Jeffrey E; Balakin, Boris V; Kellerman, Brad M; Wrolstad, David K

2013-07-01

The goal of this research was to compare side-to-side (STS) and end-to-side (ETS) anastomoses in a computer model of the arteriovenous fistula with computational fluid dynamic analysis. A matrix of 17 computer arteriovenous fistula models (SolidWorks, Dassault Systèmes, France) of artery-vein pairs (3-mm-diameter artery + 3-mm-diameter vein and 4-mm-diameter artery +6-mm-diameter vein elliptical anastomoses) in STS, 45° ETS, and 90° ETS configurations with cross-sectional areas (CSAs) of 3.5 to 18.8 mm(2) were evaluated with computational fluid dynamic software (STAR-CCM+; CD-adapco, Melville, NY) in simulations at defined flow rates from 600 to 1200 mL/min and mean arterial pressures of 50 to 140 mm Hg. Models and configurations were evaluated for pressure drop across the anastomosis, arterial inflow, venous outflow, arterial outflow, velocity vector, and wall shear stress (WSS) profile. Pressure drop across the anastomosis was inversely proportional to anastomotic CSA and to venous outflow and was proportional to arterial inflow. Pressure drop was greater in 3 + 3 models than in 4 + 6 STS models; 90° ETS configurations had the lowest pressure drops and were nearly identical, whereas 45° ETS configurations had the highest pressure drops. Venous outflow in the 4 + 6 model in STS configurations, evaluated at 100 mm Hg arterial inflow pressure, was 390, 592, 610, and 886 mL/min in anastomotic CSAs of 3.5, 5.3, 7.1, and 18.8 mm(2), respectively, and was similar in 90° ETS (609 and 908 mL/min) and lower in 45° ETS (534 and 562 mL/min) configurations at CSAs of 5.3 and 18.8 mm(2). The mean increase in venous outflow was 69 mL/min (range, -59 to 134) between 3 + 3 and 4 + 6 models at 100 mm Hg arterial inflow. The most uniform WSS profile occurs in STS anastomoses followed by 45° ETS and then 90° ETS anastomoses. The STS and 90° ETS anastomoses have high venous outflow and a tendency toward reversed arterial outflow. The 45° ETS anastomosis has reduced venous

Role of graft oversizing in the fixation strength of barbed endovascular grafts.

Science.gov (United States)

Kratzberg, Jarin A; Golzarian, Jafar; Raghavan, Madhavan L

2009-06-01

The role of endovascular graft oversizing on risk of distal graft migration following endovascular aneurysm repair for abdominal aortic aneurysm is poorly understood. A controlled in vitro investigation of the role of oversizing in graft-aorta attachment strength for endovascular grafts (EVGs) with barbs was performed. Barbed stent grafts (N = 20) with controlled graft oversizing varying from 4-45% were fabricated while maintaining other design variables unchanged. A flow loop with physiological flow characteristics and a biosynthetic aortic aneurysm phantom (synthetic aneurysm model with a bovine aortic neck) were developed. The stent grafts were deployed into the aortic neck of the bio-synthetic aortic aneurysm phantom under realistic flow conditions. Computed tomography imaging of the graft-aorta complex was used to document attachment characteristics such as graft apposition, number of barbs penetrated, and penetration depth and angle. The strength of graft attachment to the aortic neck was assessed using mechanical pullout testing. Stent grafts were categorized into four groups based on oversizing: 4-10%; 11-20%; 21-30%; and greater than 30% oversizing. Pullout force, a measure of post-deployment fixation strength was not different between 4-10% (6.23 +/- 1.90 N), 11-20% (6.25 +/- 1.84 N) and 20-30% (5.85 +/- 1.89 N) groups, but significantly lower for the group with greater than 30% oversizing (3.67 +/- 1.41 N). Increasing oversizing caused a proportional decrease in the number of barbs penetrating the aortic wall (correlation = -0.83). Of the 14 barbs available in the stent graft, 89% of the barbs (12.5 of 14 on average) penetrated the aortic wall in the 4-10% oversizing group while only 38% (5.25 of 14) did for the greater than 30% group (P barb penetration were found to be positively correlated to pullout force. Greater than 30% graft oversizing affects both barb penetration and graft apposition adversely resulting in a low pullout force in this in vitro

Pulmonale arteriovenøse malformationer, moderne behandlingsprincipper

DEFF Research Database (Denmark)

Andersen, P E; Kjeldsen, A D

2001-01-01

Pulmonary arteriovenous malformations are congenital vascular malformations in the lungs, which act as shunts so that the blood is not oxygenated or filtered. These patients are typically hypoxaemic with exercise intolerance and are at high risk of paradoxical emboli to the brain. About 25...... technical success and few complications. Embolisation prevents cerebral stroke and abscess and pulmonary haemorrhage and further raises the functional level. Screening for pulmonary arteriovenous malformations in patients at risk is recommended....

Anaesthetic management of a child with massive extracranial arteriovenous malformation

Directory of Open Access Journals (Sweden)

Faisal Shamim

2012-01-01

Full Text Available Vascular tumors affect the head and neck commonly but arteriovenous malformations are rare. Vascular malformations are often present at birth and grow with the patient, usually only becoming significant later in childhood. Embolization has been the mainstay of treatment in massive and complex arteriovenous malformations. We present a case of massive extracranial arteriovenous malformation in a 7-year-old boy causing significant workload on right heart and respiratory distress. The management of angioembolization under general anaesthesia and anaesthetic concerns are presented.

Physical examination of the hemodialysis arteriovenous fistula to detect early dysfunction.

Science.gov (United States)

Abreo, Kenneth; Amin, Bakhtiar M; Abreo, Adrian P

2018-04-01

The maintenance of vascular access patency for end-stage renal disease patients on hemodialysis is necessary for survival. Many nephrologists, nurse practitioners, and nurses have limited experience with the physical examination of the arteriovenous fistula. In this review, we define key terms used in the assessment of an arteriovenous fistula. We discuss the arteriovenous fistula physical exam, including details of inspection, palpation, and auscultation. Using these concepts, we review the abnormal findings that can assist practitioners in determining the location of a stenosis. We review the existing literature that validates physical exam findings with gold standard tests such as ultrasound and angiography. Finally, we review data supporting the value of training physicians and nurses in arteriovenous fistula physical examination.

Transarterial embolization for hematuria caused by renal arteriovenous malformations or fistulae

International Nuclear Information System (INIS)

Meng Xiaoxi; Liu Shiyuan; Dong Weihua; Dong Sheng; Jia Ningyang; Xiao Xiangsheng

2008-01-01

Objective: To evaluate the efficacy and safety of transarterial embolization for hematuria caused by renal arteriovenous malformation or fistulae. Methods: Seven patients with gross hematuria caused by renal arterial abnormalities were retrospectively reviewed, of which three had congenital renal arteriovenous malformations and the other four had non-neoplastic acquired renal arteriovenous fistulae. All patients were confirmed by renal arterial angiography and undergone embolization with various embolic materials. Results: Embolization was successfully carried out in all cases. Gross hematuria disappeared one to seven days after the procedure. No severe complications were encountered. No recurrence occurred within 12 to 36 months of follow-up. Conclusions: Transarterial embolization is safe and effective for hematuria caused by renal arteriovenous malformations or fistulae. (authors)

Surgical excision of a cerebral arteriovenous malformation in a dog

International Nuclear Information System (INIS)

Thomas, W.B.; Schueler, R.O.; Kornegay, J.N.

1995-01-01

A 7-year-old dog was presented with seizures and epistaxis. Computed tomography showed a contrast-enhancing lesion in the cerebrum. An arteriovenous malformation was identified at surgery and resected. A discussion of intracranial arteriovenous malformation is presented

Surgical treatment for a complex congenital arteriovenous malformation of the lower limb.

Science.gov (United States)

Ozcan, Ali Vefa; Boysan, Emre; Isikli, Osman Yasar; Goksin, Ibrahim

2013-01-01

Arteriovenous fistula is defined as an abnormal communication between the arterial and venous systems. The complexity of congenital arteriovenous malformations makes treatment challenging. We present the case of a 23-year-old woman who had a complex congenital arteriovenous malformation in her left leg and a history of 2 unsuccessful coil-embolization procedures. We ligated all the feeding arteries of the arteriovenous malformation in the region of the superficial femoral artery, and the surgery was successful without sequelae. The patient returned 2 years later with thrombosis of the great saphenous vein and underwent a second operation. The thrombosed vein and all varicosities were excised successfully. Surgery can be an effective method for correcting complex congenital arteriovenous malformations, especially in the lower limbs. A 2-staged surgical approach like ours might be a good option in suitable patients.

Screening for pulmonary arteriovenous malformations

DEFF Research Database (Denmark)

Oxhøj, H; Kjeldsen, A D; Nielsen, G

2000-01-01

Pulmonary arteriovenous malformations (PAVM) cause right-to-left shunt and imply risk of paradoxical embolism and cerebral abscess. These complications can be prevented by appropriate treatment. Detection of PAVMs is therefore important, so simple and reliable screening methods are needed...... for this purpose. The aim of this investigation was to compare pulse oximetry and contrast echocardiography as screening tools for detection of pulmonary arteriovenous malformations. Eighty-five hereditary haemorrhagic telangiectasia (HHT) patients and first-degree relatives identified in a comprehensive study...... echocardiography with intravenous injection of echo contrast was performed in all subjects. Outcome measures were oxygen saturation change >2% units on changing body position and echo contrast observed in the left-sided heart chambers. Positive contrast echocardiography indicating the presence of PAVM was found...

Transcatheter arterial ethanol embolization for congenital renal arteriovenous malformations

International Nuclear Information System (INIS)

Wang Jingbing; Wang Han; An Xiao; Wang Linchuan; Gao Liqiang; Zhou Zhiguo; Zhang Guixiang

2010-01-01

Objective: To discuss the effect and safety of trans-microcatheter arterial embolization with ethanol for the treatment of congenital renal arteriovenous malformations. Methods: Clinical data of 11 patients with congenital renal arteriovenous malformations manifested mainly as gross hematuria were retrospectively analyzed. Selective renal angiography was performed in all 11 patients. After the diagnosis was confirmed, super-selective catheterization of the diseased arteries was carried out and the trans-microcatheter arterial embolization with ethanol was conducted. Results: A total of 12 procedures were completed in 11 patients. The ethanol dose used in one procedure was 5-25 ml. Successful embolization of the congenital renal arteriovenous malformations was obtained in all patients. The gross hematuria disappeared within 24-48 hours after the treatment. Lumbago at treated side, low fever, abdominal distension, nausea, vomiting, etc. occurred within one week and no other serious complications developed. During the follow-up period lasting for 4-96 months, no recurrence of hematuria was observed and the renal function remained normal. Conclusion: Transcatheter arterial ethanol embolization is an economic, safe and effective treatment for congenital renal arteriovenous malformations. (authors)

Symmetry reduction of loop quantum gravity

International Nuclear Information System (INIS)

Brunnemann, Johannes; Koslowski, Tim A

2011-01-01

The relation between standard loop quantum cosmology (LQC) and full loop quantum gravity (LQG) fails already at the first nontrivial step: the configuration space of LQC cannot be embedded into the configuration space of full LQG due to a topological obstruction. We investigate this obstruction in detail, because many topological obstructions are the source of physical effects. For this, we derive the topology of a large class of subspaces of the LQG configuration space. This allows us to find the extension of the standard LQC configuration space that admits an embedding in agreement with Fleischhack (arXiv:1010.0449v1 [math-ph]). We then construct the embedding for flat FRW LQC and find the reassuring result that it coincides asymptotically with standard LQC. (paper)

Transcatheter arterial embolization for congenital renal arteriovenous malformation

International Nuclear Information System (INIS)

Zhou Jun; Hu Tingyang; Yuan Jianhua; Yu Wenqiang

2008-01-01

Objective: To evaluate the effectiveness of transcatheter arterial embolization for congenital renal arteriovenous malformation. Methods: Seven cases of congenital renal arteriovenous malformation causing gross hematuria were retrospectively studied. All of 7 cases were demonstrated by means of angiography and then the catheter was placed superselectively into the involved arterial end of the malformation undertaking embolization with gelfoam, dehydrated ethanol, coils, etc. Results: All the malformations of the 7 cases were successfully embolized with stoppage of gross hematuria within 24 hours. No serious complications occurred except lumbago, fever, gastrointestinal reaction for one week. There was no recurrence of haematuria and the renal function was also normal in all cases during the follow-up for 36 to 98 months. Conclusions: Transcatheter renal arterial angiography and embolization are the important and effective management for the diagnosis and treatment of congenital renal arteriovenous malformation. (authors)

Graft fixation with predetermined tension using a new device, the double spike plate.

Science.gov (United States)

Shino, Konsei; Mae, Tatsuo; Maeda, Akira; Miyama, Takahide; Shinjo, Hirotaka; Kawakami, Hideo

2002-10-01

To biomechanically evaluate a new fixation device, DSP (Double Spike Plate; Meira Corp, Nagoya, Aichi, Japan), for pullout graft fixation. Biomechanical study. A porcine tibia in which 8-mm diameter drill holes had been made from the medial tibial metaphysis to the anterior cruciate ligament attachment was rigidly fixed to a tension analyzer. A quadrupled graft consisting of 2 double-looped bovine tendons was prepared with No. 3 polyester sutures placed distally. The graft was passed through the drill hole, and its proximal loop ends were rigidly fixed to a load cell for monitoring graft tension. The graft's distal ends were connected to the DSP by tying the sutures to the top hole in the DSP. The graft tension was predetermined at 49 N (n = 5) or 98 N (n = 5). This tension was maintained for 5 minutes with a suture passed through the bottom hole of the DSP. The plate was fixed to the tibia by hammering its spikes into the bone under the index tension. Finally, the fixation was completed by inserting a screw. Although the graft tension immediately increased to 69 +/- 11 N or 133 +/- 14 N during hammering, it gradually reduced to 49 +/- 10 N or 100 +/- 7 N 5 minutes later. This study shows that graft fixation under a predetermined tension can be achieved with the DSP.

Determination of blood flow through arteriovenous fistulae and shunts

International Nuclear Information System (INIS)

Lantz, B.M.T.; Holcroft, J.W.; Foerster, J.M.; Link, D.P.; Reid, M.H.

1979-01-01

A videodensitometric method for estimating relative flow was employed in a patient with a bovine arteriovenous fistula. Analogous arteriovenous communications of different sizes were created in two dogs for comparison. Local and general hemodynamic parameters were measured. The videodensitometric method proved to be highly accurate compared to electromagnetic flow readings and is the method of choice in estimating shunt flow in connection with routine angiography. (Auth.)

Surgical experience with arteriovenous malformations of the brain

International Nuclear Information System (INIS)

Stein, B.M.

1984-01-01

Personal experience with the treatment of 200 arteriovenous malformations of the brain seen during the past decade is presented. One hundred and twenty of these patients underwent surgery, with a mortality of 1,7%. The morbidity rate of 10% includes cases of hemianopia after occipital malformations had been removed. Significant morbidity, including aphasia, hemiparesis and hemisensory loss, occurred in under 10% of cases. Computerized tomography plays an important role in determining the relationships of the arteriovenous malformations to associated structures such as the ventricular system

Engineering Analysis of Intermediate Loop and Process Heat Exchanger Requirements to Include Configuration Analysis and Materials Needs

Energy Technology Data Exchange (ETDEWEB)

T.M. Lillo; R.L. Williamson; T.R. Reed; C.B. Davis; D.M. Ginosar

2005-09-01

The need to locate advanced hydrogen production facilities a finite distance away from a nuclear power source necessitates the need for an intermediate heat transport loop (IHTL). This IHTL must not only efficiently transport energy over distances up to 500 meters but must also be capable of operating at high temperatures (>850oC) for many years. High temperature, long term operation raises concerns of material strength, creep resistance and general material stability (corrosion resistance). IHTL design is currently in the initial stages. Many questions remain to be answered before intelligent design can begin. The report begins to look at some of the issues surrounding the main components of an IHTL. Specifically, a stress analysis of a compact heat exchanger design under expected operating conditions is reported. Also the results of a thermal analysis performed on two ITHL pipe configurations for different heat transport fluids are presented. The configurations consist of separate hot supply and cold return legs as well as annular design in which the hot fluid is carried in an inner pipe and the cold return fluids travels in the opposite direction in the annular space around the hot pipe. The effects of insulation configurations on pipe configuration performance are also reported. Finally, a simple analysis of two different process heat exchanger designs, one a tube in shell type and the other a compact or microchannel reactor are evaluated in light of catalyst requirements. Important insights into the critical areas of research and development are gained from these analyses, guiding the direction of future areas of research.

Emergency hepatectomy for hepatic arteriovenous malformation combined with pulmonary hypertension in an infant

Directory of Open Access Journals (Sweden)

Naruhiko Murase

2015-12-01

Full Text Available Patients with hepatic arteriovenous malformations rarely present with pulmonary hypertension. We report the case of a 3-month-old boy who developed severe pulmonary hypertension due to a hepatic arteriovenous malformation. The use of pulmonary vasodilators to treat the patient's pulmonary hypertension worsened his high-output heart failure. This is the first case in which emergency hepatectomy rescued a patient with hepatic arteriovenous malformations who developed pulmonary hypertension.

Ileocolic Arteriovenous Fistula with Superior Mesenteric Vein Aneurism: Endovascular Treatment

International Nuclear Information System (INIS)

Gregorio, Miguel Angel de; Gimeno, Maria Jose; Medrano, Joaquin; Schoenholz, Caudio; Rodriguez, Juan; D'Agostino, Horacio

2004-01-01

We report a case of a venous aneurysm secondary to an acquired ileocolic arteriovenous fistula in a 64-year-old woman with recurrent abdominal pain and history of appendectomy. The aneurysm was diagnosed by ultrasound and computed tomography. Angiography showed an arteriovenous fistula between ileocolic branches of the superior mesenteric artery and vein. This vascular abnormality was successfully treated with coil embolization

Cutaneous blood flow rate in areas with and without arteriovenous anastomoses during exercise

DEFF Research Database (Denmark)

Midttun, M.; Sejrsen, Per

1998-01-01

Arteriovenous anastomoses, capillaries, cutaneous bllod flow rate, exercise, finger blood flow, skin blood flow......Arteriovenous anastomoses, capillaries, cutaneous bllod flow rate, exercise, finger blood flow, skin blood flow...

Blood compatibility assessment of graft copolymer (NR-g-DMAA) tubes

International Nuclear Information System (INIS)

Razzak, M.T.; Otsuhata, Kazushige; Tabata, Yoneho; Ohashi, Fumio; Takeuchi, Atsuki

1992-01-01

Graft copolymer (NR-g-DMAA) tubes have been prepared using simultaneous radiation induced grafting of N,N-dimethyl-acrylamide, (DMAA) onto natural rubber (NR) tubes. The blood compatibility of the NR-g-DMAA tubes was assessed with three methods, namely in vitro test, ex vivo once through test and ex vivo loops test. In the case of the in vitro test, a simple whole blood contacting procedure has been employed. The ex vivo once through test involves the exposing of NR-g-DMAA tubes with once through flow of fresh canine blood and then it was inspected for any evidence of clot. In the case of ex vivo loops test, the NR-g-DMAA tube was implanted at external jugular vein of a mongrel canine and the blood flow in the NR-g-DMAA tube was detected with an ultrasonic flow meter. It was found that the blood compatibility of NR-g-DMAA tubes is improved significantly with the increasing degree of grafting. All the NR-g-DMAA tubes having a degree of grafting of about 30 wt% or more exhibit good blood compatibility. It was found that the blood compatibility of the NR-g-DMAA tube is better than that of a medical grade silicon rubber (SiR) tube. (Author)

LoopX: A Graphical User Interface-Based Database for Comprehensive Analysis and Comparative Evaluation of Loops from Protein Structures.

Science.gov (United States)

Kadumuri, Rajashekar Varma; Vadrevu, Ramakrishna

2017-10-01

Due to their crucial role in function, folding, and stability, protein loops are being targeted for grafting/designing to create novel or alter existing functionality and improve stability and foldability. With a view to facilitate a thorough analysis and effectual search options for extracting and comparing loops for sequence and structural compatibility, we developed, LoopX a comprehensively compiled library of sequence and conformational features of ∼700,000 loops from protein structures. The database equipped with a graphical user interface is empowered with diverse query tools and search algorithms, with various rendering options to visualize the sequence- and structural-level information along with hydrogen bonding patterns, backbone φ, ψ dihedral angles of both the target and candidate loops. Two new features (i) conservation of the polar/nonpolar environment and (ii) conservation of sequence and conformation of specific residues within the loops have also been incorporated in the search and retrieval of compatible loops for a chosen target loop. Thus, the LoopX server not only serves as a database and visualization tool for sequence and structural analysis of protein loops but also aids in extracting and comparing candidate loops for a given target loop based on user-defined search options.

Phase transitions in single macromolecules: Loop-stretch transition versus loop adsorption transition in end-grafted polymer chains

Science.gov (United States)

Zhang, Shuangshuang; Qi, Shuanhu; Klushin, Leonid I.; Skvortsov, Alexander M.; Yan, Dadong; Schmid, Friederike

2018-01-01

We use Brownian dynamics simulations and analytical theory to compare two prominent types of single molecule transitions. One is the adsorption transition of a loop (a chain with two ends bound to an attractive substrate) driven by an attraction parameter ɛ and the other is the loop-stretch transition in a chain with one end attached to a repulsive substrate, driven by an external end-force F applied to the free end. Specifically, we compare the behavior of the respective order parameters of the transitions, i.e., the mean number of surface contacts in the case of the adsorption transition and the mean position of the chain end in the case of the loop-stretch transition. Close to the transition points, both the static behavior and the dynamic behavior of chains with different length N are very well described by a scaling ansatz with the scaling parameters (ɛ - ɛ*)Nϕ (adsorption transition) and (F - F*)Nν (loop-stretch transition), respectively, where ϕ is the crossover exponent of the adsorption transition and ν is the Flory exponent. We show that both the loop-stretch and the loop adsorption transitions provide an exceptional opportunity to construct explicit analytical expressions for the crossover functions which perfectly describe all simulation results on static properties in the finite-size scaling regime. Explicit crossover functions are based on the ansatz for the analytical form of the order parameter distributions at the respective transition points. In contrast to the close similarity in equilibrium static behavior, the dynamic relaxation at the two transitions shows qualitative differences, especially in the strongly ordered regimes. This is attributed to the fact that the surface contact dynamics in a strongly adsorbed chain is governed by local processes, whereas the end height relaxation of a strongly stretched chain involves the full spectrum of Rouse modes.

Relative risk of hemorrhage during pregnancy in patients with brain arteriovenous malformations

NARCIS (Netherlands)

van Beijnum, Janneke; Wilkinson, Tim; Whitaker, Heather J.; van der Bom, Johanna G.; Algra, Ale; Vandertop, W. Peter; van den Berg, René; Brouwer, Patrick A.; Rinkel, Gabriël Je; Kappelle, L. Jaap; Al-Shahi Salman, Rustam; Klijn, Catharina Jm

2017-01-01

Background It is unclear whether the risk of bleeding from brain arteriovenous malformations is higher during pregnancy, delivery, or puerperium. We compared occurrence of brain arteriovenous malformation hemorrhage in women during this period with occurrence of hemorrhage outside this period during

Endovascular repair of arterial iliac vessel wall lesions with a self-expandable nitinol stent graft system.

Directory of Open Access Journals (Sweden)

Birger Mensel

Full Text Available To assess the therapeutic outcome after endovascular repair of iliac arterial lesions (IALs using a self-expandable Nitinol stent graft system.Between July 2006 and March 2013, 16 patients (13 males, mean age: 68 years with a self-expandable Nitinol stent graft. A total of 19 lesions were treated: nine true aneurysms, two anastomotic aneurysms, two dissections, one arteriovenous fistula, two type 1B endoleaks after endovascular aneurysm repair, one pseudoaneurysm, and two perforations after angioplasty. Pre-, intra-, and postinterventional imaging studies and the medical records were analyzed for technical and clinical success and postinterventional complications.The primary technical and clinical success rate was 81.3% (13/16 patients and 75.0% (12/16, respectively. Two patients had technical failure due to persistent type 1A endoleak and another patient due to acute stent graft thrombosis. One patient showed severe stent graft kinking on the first postinterventional day. In two patients, a second intervention was performed. The secondary technical and clinical success rate was 87.5% (14/16 and 93.8% (15/16. The minor complication rate was 6.3% (patient with painful hematoma at the access site. The major complication rate was 6.3% (patient with ipsilateral deep vein thrombosis. During median follow-up of 22.4 months, an infection of the aneurysm sac in one patient and a stent graft thrombosis in another patient were observed.Endovascular repair of various IALs with a self-expandable Nitinol stent graft is safe and effective.

Prevalence of brain arteriovenous malformations in first-degree relatives of patients with a brain arteriovenous malformation

NARCIS (Netherlands)

van Beijnum, Janneke; van der Worp, H. Bart; Algra, Ale; Vandertop, W. Peter; van den Berg, René; Brouwer, Patrick A.; van der Sprenkel, Jan Willem Berkelbach; Kappelle, L. Jaap; Rinkel, Gabriël J. E.; Klijn, Catharina J. M.

2014-01-01

It is uncertain whether familial occurrence of brain arteriovenous malformations (BAVMs) represents coincidental aggregation or a shared familial risk factor. We aimed to compare the prevalence of BAVMs in first-degree relatives (FDRs) of patients with BAVM and the prevalence in the general

Spontane abdominale arteriovenøse fistler

DEFF Research Database (Denmark)

Flarup, S; Lindholt, Jes Sanddal

1997-01-01

Spontaneous arteriovenous fistulas between major abdominal vessels (AAVF) complicates about 1% of abdominal aortic aneurysms. AAVF produces severe circulatory disturbances with high operative mortality. Preoperative diagnosis is important but difficult due to the varied nature of presentation. Fo...

Post-traumatic arteriovenous fistula of the hepatic pedicle.

Science.gov (United States)

Ibn Majdoub Hassani, K; Mohsine, R; Belkouchi, A; Bensaid, Y

2010-10-01

Hepatico-portal fistula (HPF) is a rare condition, most often of post-traumatic or iatrogenic origin and occasionally secondary to a ruptured aneurysm of the hepatic artery into the portal vein. HPF in extrahepatic locations often results in portal hypertension (PHT). While Doppler ultrasound, CT angiography, and magnetic resonance angiography are usually demonstrative, arteriography remains indispensable to clarify the exact anatomical configuration. In the treatment of these arteriovenous (AV) fistulas, open surgical approaches have increasingly given way to radiological embolization techniques, especially in intrahepatic locations, but surgery remains indicated for AV fistulas of the hepatic pedicle where maintenance of hepatic arterial flow is a priority of treatment. We report a patient who had an AV fistula of the hepatic pedicle with resultant PHT presenting 5 years after open abdominal trauma. Treatment was surgical; the immediate and long-term postoperative course was uneventful with regression of PHT. Through analysis of this case and a review of the literature, we discuss the clinical, paraclinical, therapeutic, and prognostic features of this lesion. Copyright © 2010. Published by Elsevier Masson SAS.

Combined spinal intramedullary arteriovenous malformation and lipomyelomeningocele

Energy Technology Data Exchange (ETDEWEB)

Weon, Y.C.; Roh, H.G.; Byun, H.S. [Samsung Medical Center, Sungkyunkwan University School of Medicine, Department of Radiology, Seoul (Korea); Chung, J.I. [Medimoa Hospital, Department of Radiology, Seoul (Korea); Eoh, W. [Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea)

2005-10-01

Combined spinal arteriovenous malformation and lipomyelomeningocele are extremely rare. We present a rare combined case of a lipomyelomeningocele with an intramedullary arteriovenous malformation (AVM) occurred at the L3-L4 level in a 30-year-old man who suffered from low back pain radiating to the lower extremities, dysuria, and frequency for 5 years. The MR studies showed an intradural mass with high-signal intensity on both T1-weighted and T2-weighted images, intermingled with multiple signal-void structures. The mass extended extradurally toward a subcutaneously forming fatty mass on the patient's back. Spinal angiography showed an AVM supplied by the radiculopial branches of the lumbar arteries and drained by tortuous, dilated, perimedullary veins. Endovascular embolization and surgical resection were performed. (orig.)

Shear accumulation as a means for evaluating risk of thromboembolic events in novel endovascular stent graft designs.

Science.gov (United States)

Suess, Taylor; Anderson, Joseph; Sherman, Andrea; Remund, Tyler; Pohlson, Kathryn; Mani, Gopinath; Gent, Stephen; Kelly, Patrick

2017-06-01

This study proposes to establish a simulation-based technique for evaluating shear accumulation in stent grafts and to use the technique to assess the performance of a novel branched stent graft system. Computational fluid dynamics models, with transient boundary conditions, particle injection, and rigid walls, simplifying assumptions were developed and used to evaluate the shear accumulation in various stent graft configurations with a healthy aorta as comparison. Shear streamlines are presented for the various configurations. Shear accumulation was also calculated for each configuration. The number of particles with shear accumulations >3.5 Pa-s for each configuration was compared with the shear accumulation values of commercially available mechanical aortic valves from the literature. The stent graft configuration with the diaphragm does have particles with shear accumulation >3.5 Pa-s. However, the percentage of particles with shear accumulation above 3.5 Pa-s is less than the two commercially available mechanical aortic valves, and more surprisingly, is smaller than in the healthy aorta. Copyright © 2016. Published by Elsevier Inc.

Surgical management of dural arteriovenous fistulas with transosseous arterial feeders involving the jugular bulb.

Science.gov (United States)

Tirakotai, W; Benes, L; Kappus, C; Sure, U; Farhoud, A; Bien, S; Bertalanffy, H

2007-01-01

Dural arteriovenous fistulas located in the vicinity of the jugular foramen are complex vascular malformations and belong to the most challenging skull base lesions to treat. The authors comprehensively analyze multiple features in a series of dural arteriovenous fistulas with transosseous arterial feeders involving the jugular bulb. Four patients who underwent surgery via the transcondylar approach to treat dural arteriovenous fistulas around the jugular foramen were retrospectively reviewed. Previously, endovascular treatment was attempted in all patients. The success of the surgical treatment was examined with postoperative angiography. Complete obliteration of the dural arteriovenous fistulas (DAVFs) was achieved in three patients, and significant flow reduction in one individual. All patients had a good postoperative outcome, and only one experienced mild hypoglossal nerve palsy. Despite extensive bone drilling, an occipitocervical fusion was necessary in only one patient with bilateral lesions. The use of an individually tailored transcondylar approach to treat dural arteriovenous fistulas at the region of the jugular foramen is most effective. This approach allows for complete obliteration of the connecting arterial feeders, and removal of bony structures containing pathological vessels.

Angiographic treatment of the arteriovenous malformation occurred after caesarean section

Directory of Open Access Journals (Sweden)

Selim Büyükkurt

2009-03-01

Full Text Available INTRODUCTION: Uterine arteriovenous malformations are classified as acquired or congenital. Caesarean section which is performed more frequently on nowadays, uterine curettage and other uterine surgeries are the most common causes of the acquired arteriovenous malformations. CASE: Twenty-two years old woman delivered her second child by caesarean section, due to history of caesarean section, was admitted with complaint of profuse vaginal bleeding 15 days after the surgery. She demonstrated the clinical features of the hypovolemic shock. At first she treated with four units of red blood suspension, two units of fresh frozen plasma and rapid infusion of the fluids. On endometrial curettage only blood and coagulum were obtained. The bleeding could only be controlled by the internal pressure of the 18 F Foley catheter. Doppler analyze of the uterus revealed a vascular malformation signifying a turbulent flow pattern with low pressure and high flow rate. A unilateral uterine artery embolization was performed her and her menstruel cycles are resumed at the fifth month of the puerperium. DISCUSSION: The clinical presentation of the uterine arteriovenous malformations depends on the localization and the dimensions of the malformation. The uterine arteriovenous malformation should be kept in mind in cases of late occurrence vaginal bleeding unresponsive to the uterotonic medications, especially in a woman with previous history of uterine damage, such as curettage or caesarean section.

The value of pre-discharge Duplex scanning in infrainguinal graft surveillance.

Science.gov (United States)

Wilson, Y G; Davies, A H; Currie, I C; McGrath, C; Morgan, M; Baird, R N; Lamont, P M

1995-08-01

Protocols and criteria for Duplex-based graft surveillance programmes (GS) vary widely as to the optimum regimens for maximising detection of "at risk" grafts. Few centres recommend starting GS before discharge. The aim of this study was to audit our experience with respect to early scanning. Vascular Studies Unit, Bristol Royal Infirmary. The records of 123 patients entering GS from January 1992 were reviewed. Patients were scanned at 1 week, 6 weeks and 3, 6, 9 and 12 months post-bypass. Haemodynamic criteria used were a peak mean velocity (PMV) less than 45 cm/s and a focal velocity disturbance with a V2/V1 ratio of 1.5 or more. Forty-six abnormalities (37% detection rate) were identified on scans within one week. In all cases, on-table completion studies with either arteriography and/or flow measurements had failed to identify the anomalies subsequently detected by Duplex. At 1 week, six grafts had occluded, 27 had a focal PMV increase (mean V2/V1 ratio: 2.6; range 1.5-4.3), four had low flow velocities, four had arteriovenous fistulae, one contained mobile thrombus, two had retained cusps and two had hamstring entrapment. Of 40 patent, but compromised grafts, 18 warranted immediate investigation. Of the 27 patients with velocity disturbances on Duplex, 25 were simply observed but, eight have since required intervention for definitive stenoses at these sites which, in retrospect, were evident within the first postoperative week. Pre-discharge scanning is a useful modality for detecting technical problems. Intrinsic graft abnormalities, possibly the sites of future definitive stenoses, have been visualised even at 1 week and once identified, can be more closely scrutinised thereafter. Pre-discharge colour Duplex is recommended as standard practice for quality control after infrainguinal bypass.

Management of patients with brain arteriovenous malformations

International Nuclear Information System (INIS)

Soederman, Michael; Andersson, Tommy; Karlsson, Bengt; Wallace, M. Christopher; Edner, Goeran

2003-01-01

Arteriovenous malformations (AVMs) of the brain, which are probably genetically determined, are errors in the development of the vasculature that, together with the effects of blood flow, may lead to a focal arteriovenous shunt. Clinically, the adult patient may present with acute or chronic neurological symptoms--fixed or unstable--such as deficits, seizures or headache. Sometimes the lesion is an incidental finding. In about half of the patients, the revealing event is an intracranial haemorrhage. The prevalence of AVM in the western world is probably 10 ml could benefit from targeted partial embolisation followed by radiosurgery or surgery, depending on the angioarchitecture; and (IV) AVMs >20 ml nidus volume usually have a high treatment risk with any treatment modality and are not obvious targets for treatment at all

Stabilization of self-mode-locked quantum dash lasers by symmetric dual-loop optical feedback

Science.gov (United States)

Asghar, Haroon; Wei, Wei; Kumar, Pramod; Sooudi, Ehsan; McInerney, John. G.

2018-02-01

We report experimental studies of the influence of symmetric dual-loop optical feedback on the RF linewidth and timing jitter of self-mode-locked two-section quantum dash lasers emitting at 1550 nm. Various feedback schemes were investigated and optimum levels determined for narrowest RF linewidth and low timing jitter, for single-loop and symmetric dual-loop feedback. Two symmetric dual-loop configurations, with balanced and unbalanced feedback ratios, were studied. We demonstrate that unbalanced symmetric dual loop feedback, with the inner cavity resonant and fine delay tuning of the outer loop, gives narrowest RF linewidth and reduced timing jitter over a wide range of delay, unlike single and balanced symmetric dual-loop configurations. This configuration with feedback lengths 80 and 140 m narrows the RF linewidth by 4-67x and 10-100x, respectively, across the widest delay range, compared to free-running. For symmetric dual-loop feedback, the influence of different power split ratios through the feedback loops was determined. Our results show that symmetric dual-loop feedback is markedly more effective than single-loop feedback in reducing RF linewidth and timing jitter, and is much less sensitive to delay phase, making this technique ideal for applications where robustness and alignment tolerance are essential.

Vascular access for home haemodialysis.

Science.gov (United States)

Al Shakarchi, Julien; Day, C; Inston, N

2018-03-01

Home haemodialysis has been advocated due to improved quality of life. However, there are very little data on the optimum vascular access for it. A retrospective cohort study was carried on all patients who initiated home haemodialysis between 2011 and 2016 at a large university hospital. Access-related hospital admissions and interventions were used as primary outcome measures. Our cohort consisted of 74 patients. On initiation of home haemodialysis, 62 individuals were using an arteriovenous fistula as vascular access, while the remaining were on a tunnelled dialysis catheter. Of the 12 patients who started on a tunnelled dialysis catheter, 5 were subsequently converted to either an arteriovenous fistula ( n = 4) or an arteriovenous graft ( n = 1). During the period of home haemodialysis use, four arteriovenous fistula failed or thrombosed with patients continuing on home haemodialysis using an arteriovenous graft ( n = 3) or a tunnelled dialysis catheter ( n = 1). To maintain uninterrupted home haemodialysis, interventional rates were 0.32 per arteriovenous fistula/arteriovenous graft access-year and 0.4 per tunnelled dialysis catheter access-year. Hospital admission rates for patients on home haemodialysis were 0.33 per patient-year. Our study has shown that home haemodialysis can be safely and independently performed at home within a closely managed home haemodialysis programme. The authors also advocate the use of arteriovenous fistulas for this cohort of patients due to both low complication and intervention rates.

Vector Volume Flow in Arteriovenous Fistulas

DEFF Research Database (Denmark)

Hansen, Peter Møller; Heerwagen, Søren; Pedersen, Mads Møller

2013-01-01

, but is very challenging due to the angle dependency of the Doppler technique and the anatomy of the fistula. The angle independent vector ultrasound technique Transverse Oscillation provides a new and more intuitive way to measure volume flow in an arteriovenous fistula. In this paper the Transverse...

Near BPS Wilson loop in β-deformed theories

International Nuclear Information System (INIS)

Chu, C-S; Giataganas, Dimitrios

2007-01-01

We propose a definition of the Wilson loop operator in the N = 1 β-deformed supersymmetric Yang-Mills theory. Although the operator is not BPS, it has a finite expectation value at least up to order (g 2 N) 2 . This does not happen generally for a generic non-BPS Wilson loop whose expectation value is UV divergent. For this reason we call this a near-BPS Wilson loop. We derive the general form of the boundary condition satisfied by the dual string worldsheet and find that it is deformed. Finiteness of the expectation value of the Wilson loop fixes the boundary condition to be one which is characterized by the vielbein of the deformed supergravity metric. The Wilson loop operators provide natural candidates as dual descriptions to some of the existing D-brane configurations in the Lunin-Maldacena background. We also construct the string dual configuration for a near-1/4 BPS circular Wilson loop operator. The string lies on a deformed three-sphere instead of a two-sphere as in the undeformed case. The expectation value of the Wilson loop operator is computed using the AdS/CFT correspondence and is found to be independent of the deformation. We conjecture that the exact expectation value of the Wilson loop is given by the same matrix model as in the undeformed case

Atypical MRI features in soft-tissue arteriovenous malformation: a novel imaging appearance with radiologic-pathologic correlation

Energy Technology Data Exchange (ETDEWEB)

Patel, Anand S. [University of California, San Francisco, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); University of California, San Francisco, Department of Interventional Radiology, San Francisco, CA (United States); Schulman, Joshua M.; Ruben, Beth S. [University of California, San Francisco, Departments of Pathology and Dermatology, San Francisco, CA (United States); Hoffman, William Y. [University of California, San Francisco, Department of Plastic Surgery, Birthmarks and Vascular Anomalies Clinic, San Francisco, CA (United States); Dowd, Christopher F. [University of California, San Francisco, Department of Interventional Neuroradiology, Birthmarks and Vascular Anomalies Clinic, San Francisco, CA (United States); Frieden, Ilona J. [University of California, San Francisco, Department of Dermatology, Birthmarks and Vascular Anomalies Clinic, San Francisco, CA (United States); Hess, Christopher P. [University of California, San Francisco, Department of Neuroradiology, Birthmarks and Vascular Anomalies Clinic, San Francisco, CA (United States)

2015-09-15

The absence of a discrete mass, surrounding signal abnormality and solid enhancement are imaging features that have traditionally been used to differentiate soft-tissue arteriovenous malformations from vascular tumors on MRI. We have observed that these findings are not uncommon in arteriovenous malformations, which may lead to misdiagnosis or inappropriate treatment. To estimate the frequency of atypical MRI features in soft-tissue arteriovenous malformations and assess their relationship to lesion size, location, tissue type involved and vascular architecture. Medical records, MRI and histopathology were reviewed in consecutive patients with soft-tissue arteriovenous malformations in a multidisciplinary vascular anomalies clinic. Arteriovenous malformations were divided into those with and without atypical MRI findings (perilesional T2 signal abnormality, enhancement and/or a soft-tissue mass). Lesion location, size, tissue involved and vascular architecture were also compared between groups. Tissue stains were reviewed in available biopsy or resection specimens to assess relationships between MRI findings and histopathology. Thirty patients with treatment-naive arteriovenous malformations were included. Fifteen lesions demonstrated atypical MRI. There was no difference in age, gender, lesion size or involved body part between the groups. However, more than half of the atypical lesions demonstrated multicompartmental involvement, and tiny intralesional flow voids were more common in atypical arteriovenous malformations. Histopathology also differed in atypical cases, showing densely packed endothelial cells with connective tissue architectural distortion and edema. Arteriovenous malformations may exhibit features of a vascular tumor on MRI, particularly when multicompartmental and/or containing tiny internal vessels. These features are important to consider in suspected fast-flow vascular malformations and may have implications with respect to their treatment

CSF in the ventricles of the brain behaves as a relay medium for arteriovenous pulse wave phase coupling.

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William E Butler

Full Text Available The ventricles of the brain remain perhaps the largest anatomic structure in the human body without established primary purpose, even though their existence has been known at least since described by Aristotle. We hypothesize that the ventricles help match a stroke volume of arterial blood that arrives into the rigid cranium with an equivalent volume of ejected venous blood by spatially configuring cerebrospinal fluid (CSF to act as a low viscosity relay medium for arteriovenous pulse wave (PW phase coupling. We probe the hypothesis by comparing the spatiotemporal behavior of vascular PW about the ventricular surfaces in piglets to internal observations of ventricle wall motions and adjacent CSF pressure variations in humans. With wavelet brain angiography data obtained from piglets, we map the travel relative to brain pulse motion of arterial and venous PWs over the ventricle surfaces. We find that arterial PWs differ in CF phase from venous PWs over the surfaces of the ventricles consistent with arteriovenous PW phase coupling. We find a spatiotemporal difference in vascular PW phase between the ventral and dorsal ventricular surfaces, with the PWs arriving slightly sooner to the ventral surfaces. In humans undergoing neuroendoscopic surgery for hydrocephalus, we measure directly ventricle wall motions and the adjacent internal CSF pressure variations. We find that CSF pressure peaks slightly earlier in the ventral Third Ventricle than the dorsal Lateral Ventricle. When matched anatomically, the peri-ventricular vascular PW phase distribution in piglets complements the endo-ventricular CSF PW phase distribution in humans. This is consistent with a role for the ventricles in arteriovenous PW coupling and may add a framework for understanding hydrocephalus and other disturbances of intracranial pressure.

Arteriovenous Malformation Detected by Small Bowel Endoscopy

Directory of Open Access Journals (Sweden)

Takaaki Fujii

2014-10-01

Full Text Available Gastrointestinal bleeding that originates in the small intestine is often difficult to diagnose. When successful diagnosis reveals a lesion that can be localized preoperatively, the laparoscopic approach is an appropriate and beneficial treatment modality for small bowel resection. A 69-year-old man presented with a 6-month history of gastrointestinal bleeding and symptomatic transfusion-dependent anemia. Upper and lower endoscopy were normal. Double-balloon endoscopy established the source of the bleeding as a 0.5-cm polypoid mass appearing as a submucosal tumor with redness and pulsation in the lower ileum, suggesting a vascular lesion. Laparoscopic small bowel resection was successful in removing the mass in the ileum. Histological evaluation of the mass revealed an arteriovenous malformation. Preoperative small bowel endoscopy can be useful for diagnosing the cause and localization of arteriovenous malformation in the small intestine.

[Value of preserved saphenous vein graft for the creation of access ports in hemodialyzed patients: report of 309 cases].

Science.gov (United States)

Schneider, Marc; Barrou, Benoît; Cluzel, Philippe; Hamani, Aziz; Bitker, Marc-Olivier; Richard, François

2003-09-01

Biological grafts are rarely used for the creation of vascular access, despite their many advantages. Our group prefers to use distal vascular accesses with interposition of a biological graft when direct access cannot be achieved. The objective of this study was to determine the long-term patency and the complication rate of a series of 309 vascular access procedures using a preserved saphenous (PS) vein homograft. 410 (27%) of the 1,500 vascular access procedures performed by our group required the use of a graft, including 376 PS vein homografts (25%). This retrospective study comprised complete data collection for 309 arteriovenous fistulas (AVF) using preserved saphenous (PS) vein graft in the forearm performed in 267 patients between 1985 and 2000. Primary patency was defined as the interval between creation of the vascular access and the first complication requiring surgical or radiological correction; secondary patency was defined as the interval between creation and loss of the graft, with or without revision of the fistula. Survival rates were calculated according to the Kaplan-Meier method. Inter-group comparison was performed by the Logrank test and analysis of variance was performed by logistic regression. Primary patency rates were 77%, 40% and 27% at 1,2 and 5 years, respectively. Secondary patency rates were 79% and 47% at 1 year and 5 years, respectively. The thrombosis rate was 42%. Two episodes of thrombosis occurred in 25% of grafts and 3 episodes were observed in 10% of cases. Infection rates were 1.9% postoperatively and 5% after dialysis, respectively. An aneurysm occurred on 10% of grafts. The operator's experience (RR = 1.58; p creation of vascular accesses with similar patency rates to those of prosthetic grafts. Vein grafts present a number of advantages, particularly a greater ease of use facilitating distal implantation of the graft and a low infection rate.

Lower Limb Arteriovenous Communications in Diabetes Mellitus: A Potential Reason for Aggravation of Ischemic Symptoms

International Nuclear Information System (INIS)

Hamady, Mohamad S.; Yu, Dominic F.; Sayer, Gabriel L.; Edmonds, Michael E.; Walters, Huw L.; Sidhu, Paul S.

2006-01-01

The aim of this study was to assess the prevalence and to evaluate the clinical associations of arteriovenous communications in patients with diabetes mellitus (DM) and lower limb peripheral arterial ischemia. Peripheral arteriography of DM patients from an eight-year period (1993-2000) was evaluated retrospectively by two observers. The presence of arteriovenous communications, defined as occurring without evidence of a preceding precipitating event, and the distribution and severity of the vascular disease were evaluated. The type (non-insulin-dependent DM or insulin-dependent DM) and the duration of the DM, the presenting symptoms, and the presence of a peripheral neuropathy were documented by a review of the clinical records. A total of 348 arteriography studies in 285 DM patients were evaluated (duration of DM: median, 16 years; range, 7-42 years); an arteriovenous communication was present in 14/285 patients (4.9%), 9 male and 5 female (median age, 71 years; range, 17-84 years). Symptoms were those of a peripheral leg ulcer (n = 11), claudication (n = 3), and gangrene (n = 1), with symptoms ipsilateral to the side of the arteriovenous communication in 13/14 patients. The sites of the arteriovenous communications were infra popliteal (n = 7), popliteal (n = 3), superficial femoral artery (n = 3), and common femoral artery (n = 1). Features of a peripheral neuropathy were found in 12/14 and ipsilateral to the side of the communication in 11/12. Arteriovenous communications in the peripheral femoral arterial system of patients with DM is an uncommon finding. Although not proven in the current study, arteriovenous communications might be associated with more severe symptoms than that attributable to the underlying vascular disease alone

Molecular Velcro constructed from polymer loop brushes showing enhanced adhesion force

Science.gov (United States)

Zhou, Tian; Han, Biao; Han, Lin; Li, Christopher; Department of Materials Science; Engineering Team; School of Biomedical Engineering, Science; Health Systems Team

2015-03-01

Molecular Velcro is commonly seen in biological systems as the formation of strong physical entanglement at molecular scale could induce strong adhesion, which is crucial to many biological processes. To mimic this structure, we designed, and fabricated polymer loop brushes using polymer single crystals with desired surface functionality and controlled chain folding. Compared with reported loop brushes fabricated using triblock copolymers, the present loop bushes have precise loop sizes, loop grafting density, and well controlled tethering locations on the solid surface. Atomic force microscopy-based force spectroscopy measurements using a polymer chain coated probe reveal that the adhesion force are significantly enhanced on the loop brush surface as compared with its single-strand counterpart. This study directly shows the effect of polymer brush conformation on their properties, and suggests a promising strategy for advanced polymer surface design.

Vertebral Arteriovenous Fistula Presenting as Cervical Myelopathy: A Rapid Recovery with Balloon Embolization

International Nuclear Information System (INIS)

Modi, Manish; Bapuraj, J. Rajiv; Lal, Anupam; Prabhakar, S.; Khandelwal, N.

2010-01-01

A 24-year-old male presented with progressive cervical myelopathy of 2 months' duration. Magnetic resonance imaging of the cervical spine and angiography revealed a large arteriovenous fistula arising from the left vertebral artery. The present case highlights the clinical features and dramatic recovery following endovascular balloon occlusion of a giant cervical arteriovenous fistula.

Determination of the force systems produced by different configurations of tear drop orthodontic loops

Directory of Open Access Journals (Sweden)

Guilherme Thiesen

2013-04-01

Full Text Available OBJECTIVE: To determine the mechanical characteristics of teardrop loop with and without helix fabricated using different metal alloy compositions (stainless steel and beta-titanium, submitted to different intensities of bends preactivation (0º and 40º, and with different cross-sectional dimension of the wire used to build these loops (0.017 x 0.025-in and 0.019 x 0.025-in. METHODS: Eighty loops used to close spaces were submitted to mechanical tests. The magnitudes of horizontal force, the moment/force ratio, and the load/deflection ratio produced by the specimens were quantified. Loops were submitted to a total activation of 5.0 mm and the values were registered for each 1.0 mm of activation. For statistic data analysis, a analysis of variance was performed and a Tukey's Multiple Comparison test was used as supplement, considering a 5% level of significance. RESULTS: In general, teardrop loops with helix produced lower magnitudes of horizontal force and load/deflection ratio, and higher moment/force ratio than teardrop loops without helix. Among all analyzed variables, metal alloy composition presented greater influence in the horizontal force and in the load/deflection ratio. The moment/force ratio showed to be more influenced by the preactivation of loops for space closure.

Arteriovenous malformation of the external ear: a clinical assessment with a scoping review of the literature

Directory of Open Access Journals (Sweden)

Shin Hye Kim

Full Text Available Abstract Introduction: Auricular Arteriovenous Malformation of the external ear is a rarely encountered disease; in particular, arteriovenous malformation arising from the auricle, with spontaneous bleeding, has seldom been reported. Objective: In the current study, we report an unusual case of late-onset auricular arteriovenous malformation originating from the posterior auricular artery that was confirmed by computed tomographic angiography. The case was successfully managed by pre-surgical intravascular embolization followed by total lesion excision. Prompted by this case, we also present a scoping review of the literature. Methods: A case of a 60 year-old man with right auricular arteriovenous malformation treated in our tertiary care center, and 52 patients with auricular arteriovenous malformation described in 10 case reports and a retrospective review are presented. Auricular arteriovenous malformation can manifest as swelling of the ear, pulsatile tinnitus, pain, and/or bleeding. On physical examination, a pulsatile swelling and/or a tender mass is evident. When arteriovenous malformation is suspected, the lesions should be visualized using imaging modalities that optimally detect vascular lesions, and managed via embolization, mass excision, or auricular resection. Effectiveness of the various diagnostic methods used and the treatment outcomes were analyzed. Results: Various imaging modalities including Doppler sonography, computed tomographic angiography, magnetic resonance angiography, and/or transfemoral cerebral angiography were used to diagnose 38 cases reported in the literature. In another 15 cases, no imaging was performed; treatment was determined solely by physical examination and auscultation. Of the total of 53 cases, 12 were not treated (their symptoms were merely observed whereas 20 underwent therapeutic embolization. In total, 32 patients, including 1 patient who was not treated and 10 with persistent or aggravated

Transmicrocatheter local injection of ethanol to treat hepatocellular carcinoma with high flow arteriovenous shunts

International Nuclear Information System (INIS)

Guan Shouhai; Shan Hong; Jiang Zaibo; Huang Mingsheng; Zhu Kangshun; Li Zhengran; Meng Xiaochun

2002-01-01

Objective: To evaluate the feasibility and clinical effect of embolization therapy in treating the high flow hepatic arteriovenous shunts in hepatocellular carcinoma (HCC) by locally injected ethanol through microcatheter. Methods: Forty-one branches of arteriovenous shunts were treated by local ethanol infusion through microcatheter in 29 patients suffered with HCC. Angiography was performed to observe the embolization effect and influence to non-targeted vessels. Result: Forty-one branches of arteriovenous shunts in 29 patients were injected with ethanol locally. Each single shunt was infused 1-6 times. The dose of ethanol was 2-3 ml per time, and the total dose of ethanol was 2-12 ml. All shunting tracts were embolized, and all non-target vessels were protected fluently. Iodine-oil deposition was well in continued TACE. Their syndromes were improved or disappeared. Conclusion: Transmicrocatheter injection of ethanol could safely and effectively treat the hepatic arteriovenous shunts and make advantages to TACE in HCC

Independent SU(2)-loop variables

International Nuclear Information System (INIS)

Loll, R.

1991-04-01

We give a reduction procedure for SU(2)-trace variables and introduce a complete set of indepentent, gauge-invariant and almost local loop variables for the configuration space of SU(2)-lattice gauge theory in 2+1 dimensions. (orig.)

Choice of Hemodialysis Access in Older Adults: A Cost-Effectiveness Analysis.

Science.gov (United States)

Hall, Rasheeda K; Myers, Evan R; Rosas, Sylvia E; O'Hare, Ann M; Colón-Emeric, Cathleen S

2017-06-07

Although arteriovenous fistulas have been found to be the most cost-effective form of hemodialysis access, the relative benefits of placing an arteriovenous fistula versus an arteriovenous graft seem to be least certain for older adults and when placed preemptively. However, older adults' life expectancy is heterogeneous, and most patients do not undergo permanent access creation until after dialysis initiation. We evaluated cost-effectiveness of arteriovenous fistula placement after dialysis initiation in older adults as a function of age and life expectancy. Using a hypothetical cohort of patients on incident hemodialysis with central venous catheters, we constructed Markov models of three treatment options: ( 1 ) arteriovenous fistula placement, ( 2 ) arteriovenous graft placement, or ( 3 ) continued catheter use. Costs, utilities, and transitional probabilities were derived from existing literature. Probabilistic sensitivity analyses were performed by age group (65-69, 70-74, 75-79, 80-84, and 85-89 years old) and quartile of life expectancy. Costs, quality-adjusted life-months, and incremental cost-effectiveness ratios were evaluated for up to 5 years. The arteriovenous fistula option was cost effective compared with continued catheter use for all age and life expectancy groups, except for 85-89 year olds in the lowest life expectancy quartile. The arteriovenous fistula option was more cost effective than the arteriovenous graft option for all quartiles of life expectancy among the 65- to 69-year-old age group. For older age groups, differences in cost-effectiveness between the strategies were attenuated, and the arteriovenous fistula option tended to only be cost effective in patients with life expectancy >2 years. For groups for which the arteriovenous fistula option was not cost saving, the cost to gain one quality-adjusted life-month ranged from $2294 to $14,042. Among older adults, the cost-effectiveness of an arteriovenous fistula placed within the first

Embolization with Gamma Knife Radiosurgery of Giant Intracranial Arteriovenous Malformations.

Science.gov (United States)

Chun, Dong Hyun; Kim, Moo Seong; Kim, Sung Tae; Paeng, Sung Hwa; Jeong, Hae Woong; Lee, Won Hee

2016-01-01

Giant arteriovenous malformations (i.e., those greater than 6 cm maximum diameter or volume > 33 cc) are difficult to treat and often carry higher treatment morbidity and mortality rates. In our study, we reviewed the angiographic results and clinical outcomes for 11 patients with giant arteriovenous malformations who were treated between 1994 and 2012. The patients selected included 9 males (82%) and 2 females (18%). Their presenting symptoms were hemorrhage (n=2; 18%), seizure (n=7; 64%), and headache (n=2; 12%). Nine patients were Spetzler-Martin Grade III, 2 were Spetzler-Martin Grade IV. The mean arteriovenous malformation volume was 41 cc (33-52 cc). The mean age of the patients was 45.1 years (24-57 years) and the mean radiation dose delivered to the margin of the nidus was 14.2 Gy. Ten patients received pre-Gamma Knife radiosurgery embolization and Gamma Knife radiosurgery, 1 patient received pre-Gamma Knife radiosurgery embolization and Gamma Knife radiosurgery twice and the interval between Gamma Knife radiosurgeries was 3 months. The complete obliteration rate following Gamma Knife radiosurgery was 36%, subtotal obliteration ( > 70% decreased size of nidus) was 36%, and partial obliteration was 28%. One patient experienced a small hemorrhage after embolization. Combined embolization and Gamma Knife radiosurgery showed successful obliteration of the arteriovenous malformation nidus. The use of embolization to initially reduce nidus size followed by Gamma Knife radiosurgery improves the treatment results. Repeated Gamma Knife radiosurgery should be a treatment option when there is a small nidus remnant.

[Pulmonary arteriovenous fistula with Rendu-Osler-Weber disease].

Science.gov (United States)

Segawa, Masataka; Touge, Masayoshi; Seki, Kouji; Kusajima, Yoshinori; Saito, Katsuhiko

2012-09-01

A 36-year-old man was admitted to our hospital for examination of a nodular shadow in the left lung. Chest 3-dimensional computed tomography (3D-CT) revealed a pulmonary arteriovenous fistula (PAVF) of 21 mm in diameter composed of the feeding artery (A4) and the draining vein (V4) in the left S4. Abdominal enhanced CT revealed multiple hepatic arteriovenous fistula. Brain CT revealed a cavernous hemangioma in right occipital cerebrum. He had a family history, habitual epistaxis, and oral telangiectasia and was diagnosed as Rendu-Osler-Weber disease (hereditary hemorrhagic telangiectasia:HHT). According to his family history, PAVF was likely to be a risk factor of brain infarction and abscess, and the wedge resection of the lingual lobe was performed to remove PAVF.

Peroneal Arteriovenous Fistula and Pseudoaneurysm: An Unusual Presentation

Directory of Open Access Journals (Sweden)

Kevin C. Ching

2014-01-01

Full Text Available Peroneal artery arteriovenous fistulas and pseudoaneurysms are extremely rare with the majority of reported cases due to penetrating, orthopedic, or iatrogenic trauma. Failure to diagnose this unusual vascular pathology may lead to massive hemorrhage or limb threatening ischemia. We report an interesting case of a 14-year-old male who presented with acute musculoskeletal pain of his lower extremity. Initial radiographs were negative. Further imaging workup revealed a peroneal arteriovenous fistula with a large pseudoaneurysm. After initial endovascular intervention was unsuccessful, the vessels were surgically ligated in the operating room. Pathology revealed papillary endothelial hyperplasia consistent with an aneurysm and later genetic testing was consistent with Ehlers-Danlos syndrome Type IV. This case illustrates an unusual cause of acute atraumatic musculoskeletal pain and uncommon presentation of Ehlers-Danlos syndrome.

Hybrid management of a spontaneous ilio-iliac arteriovenous fistula: a case report

LENUS (Irish Health Repository)

O'Brien, Gavin C

2011-08-22

Abstract Introduction Spontaneous iliac arteriovenous fistulae are a rare clinical entity. Such localized fistulation is usually a result of penetrating traumatic or iatrogenic injury. Clinical presentation can vary greatly but commonly includes back pain, high-output congestive cardiac failure and the presence of an abdominal bruit. Diagnosis, therefore, is often incidental or delayed. Case presentation We report a case of a spontaneous ilio-iliac arteriovenous fistula in a 68-year-old Caucasian man detected following presentation with unilateral claudication and congestive cardiac failure. Following computed tomography evaluation, the fistula was successfully treated with a combined endovascular (aorto-uni-iliac device) and open (femoro-femoral crossover) approach. Conclusion Endovascular surgery has revolutionized the management of such fistulae and we report an interesting case of a high-output iliac arteriovenous fistulae successfully treated with a hybrid vascular approach.

Effect of steam generator configuration in a loss of the RHR during mid-loop operation at PKL facility

Energy Technology Data Exchange (ETDEWEB)

Villanueva, J. F.; Carlos, S.; Martorell, S.; Sanchez, F. [Dpto. Ingenieria Quimica Y Nuclear, Universitat Politecnica de Valencia, Camino Vera s/n, 46022 Valencia (Spain)

2012-07-01

The loss of the residual heat removal system in mid-loop conditions may occur with a non-negligible contribution to the plant risk, so the analysis of the accidental sequences and the actions to mitigate the accident are of great interest in shutdown conditions. In order to plan the appropriate measures to mitigate the accident is necessary to understand the thermal-hydraulic processes following the loss of the residual heat removal system during shutdown. Thus, transients of this kind have been simulated using best-estimate codes in different integral test facilities and compared with experimental data obtained in different facilities. In PKL (Primaerkreislauf-Versuchsanlage, primary coolant loop test facility) test facility different series of experiments have been undertaken to analyze the plant response in shutdown. In this context, the E3 and F2 series consist of analyzing the loss of the residual heat removal system with a reduced inventory in the primary system. In particular, the experiments were developed to investigate the influence of the steam generators secondary side configuration on the plant response, what involves the consideration of different number of steam generators filled with water and ready for activation, on the heat transfer mechanisms inside the steam generators U-tubes. This work presents the results of such experiments calculated using, RELAP5/Mod 3.3. (authors)

[A vertebral arteriovenous fistula diagnosed by auscultation].

Science.gov (United States)

Iglesias Escalera, G; Diaz-Delgado Peñas, R; Carrasco Marina, M Ll; Maraña Perez, A; Ialeggio, D

2015-01-01

Cervical artery fistulas are rare arteriovenous malformations. The etiology of the vertebral arteriovenous fistulas (AVF) can be traumatic or spontaneous. They tend to be asymptomatic or palpation or continuous vibration in the cervical region. An arteriography is necessary for a definitive diagnosis. The treatment is complete embolization of the fistula. We present the case of a two year-old male, where the mother described it «like a washing machine in his head». On palpation during the physical examination, there was a continuous vibration, and a continuous murmur in left cervical region. A vascular malformation in vertebral region was clinically suspected, and confirmed with angio-MRI and arteriography. AVF are rare in childhood. They should be suspected in the presence of noises, palpation or continuous vibration in the cervical region. Early diagnosis can prevent severe complications in asymptomatic children. Copyright © 2013 Asociación Española de Pediatría. Published by Elsevier Espana. All rights reserved.

Indocyanine green videoangiography "in negative": definition and usefulness in intracranial dural arteriovenous fistulae.

Science.gov (United States)

Simal Julián, Juan Antonio; Miranda Lloret, Pablo; Aparici Robles, Fernando; Beltrán Giner, Andrés; Botella Asunción, Carlos

2013-09-01

Indocyanine green videoangiography (IGV) raises important limitations when we use it in vascular pathology, especially in cases with arterialization of the venous system such as arteriovenous malformations and fistulae. Our objective was to provide a simple procedure that overcomes the limitations of conventional IGV. We define IGV in negative (IGV-IN), so-called because, in its first phase, the vessel to analyze is clipped, and we report 3 cases of intracranial dural arteriovenous fistulae treated with this procedure. In 2011, we applied IGV-IN to 3 patients at our center with Borden type III intracranial arteriovenous fistulae. In all 3 cases, IGV-IN enabled both diagnosis and post-dural arteriovenous fistula exclusion control in 1 integrated procedure no longer than 1 minute, requiring only 1 visualization. IGV-IN is an improvement over the conventional IGV method and is able to provide more information in a shorter period of time. It is an intuitive and highly visual procedure, and, more importantly, it is reversible. Studies with larger samples are necessary to determine whether IGV-IN can further reduce the need for postoperative digital subtraction angiography.

Endovascular repair of posttraumatic multiple femoral-femoral and popliteal-popliteal arteriovenous fistula with Viabahn and excluder stent graft

Directory of Open Access Journals (Sweden)

Šarac Momir

2011-01-01

Full Text Available Background. Traumatic arteriovenous (AV fistula is considered to be a pathologic communication between the arterial and venous systems following injury caused mostly by firearms, sharp objects or blasting agents. Almost 50% of all traumatic AV fistulas are localized in the extremities. In making diagnosis, besides injury anamnesis data, clinical image is dominated by palpable thrill and auscultator continual sounds at the site of fistula, extremities edemas, ischemia distally of fistula, pronounced varicose syndrome, and any signs of the right heart load in high-flow fistulas. Case report. We presented a male 32-year-old patient self-injured the region of the right lower and upper leg by shotgun during hunting in 2005. The same day the patient was operated on in a tertiary traumatology health care institution under the diagnosis of vulnus sclopetarium femoris et cruris dex; AV fistula reg popliteae dex; fractura cruris dex. The performed surgery was ligatura AV fistulae; reconstructio a. popliteae cum T-T anastomosis; fasciotomia cruris dex. Postoperatively, in the patient developed a multiple AV fistula of the femoral and popliteal artery and neighboring veins. The patient was two more times operated on for closing the fistula but with no success. Three years later the patient was referred to the Clinic for Vascular Surgery, Military Medical Academy, Belgrade, Serbia. A physical examination on admission showed the right upper leg edema, pronounced varicosities and high thrill, signs of the skin induration and initial ischemia with ulceration in the right lower leg, as well as numerous scars in the inner side of the leg from the previously performed operations. Due to the right heart load there were also present easy getting tired, tachypnoea and tachycardia. CT and contrast angiography verified the presence of multiple traumatic AV fistulas in the surface femoral and popliteal artery and neighboring veins of the highest diameter being 1 cm

Proteomic Profiling in Early Venous Stenosis Formation in a Porcine Model of Hemodialysis Graft

Science.gov (United States)

Misra, Sanjay; Fu, Alex A.; Puggioni, Alessandra; Glockner, James F.; McKusick, Michael A.; Bjarnason, Haraldur; Mukhopadhyay, Debabrata

2009-01-01

PURPOSE To use proteomic analysis to identify up- and downregulated proteins in early venous stenosis formation in a porcine model of hemodialysis graft failure. MATERIALS AND METHODS Pigs had chronic renal insufficiency created by subtotal renal infarction caused by renal artery embolization. Arteriovenous polytetrafluoroethylene grafts were placed 28 days later and the animals were killed after a further 3 days (n = 4), 7 days (n = 4), or 14 days (n = 4). Proteomic analysis with isotope-coded affinity tags and multidimensional liquid chromatography followed by tandem mass spectrometry was performed on the venous stenosis and control vessels. Expression of proteins was further confirmed by Western blot analysis. The blood urea nitrogen (BUN) and creatinine levels were determined before renal artery embolization and at the time of graft placement. RESULTS At graft placement, mean BUN and creatinine levels were significantly higher than before embolization (P < .05). Six proteins were identified that were common to all four animals at the same time point. Five proteins (α-fetoprotein, fetuin A, macrophage migration inhibitory factor, pyruvate dehydrogenase E1 component, and lactoferrin) were upregulated and one protein (decorin) was downregulated. Expression of macrophage migration inhibitory factor, α-fetoprotein, and lactoferrin was further validated with Western blotting. By day 14, lactoferrin and fetuin-A expression were increased significantly in early venous stenosis formation. CONCLUSIONS Significantly increased expression of lactoferrin and fetuin-A were observed in early venous stenosis by day 14. Understanding the role of lactoferrin and fetuin-A in hemodialysis vascular access failure could help in improving outcomes in patients undergoing hemodialysis. PMID:19028119

Natural Circulation Characteristics of a Symmetric Loop under Inclined Conditions

Directory of Open Access Journals (Sweden)

Xingtuan Yang

2014-01-01

Full Text Available Natural circulation is an important process for primary loops of some marine integrated reactors. The reactor works under inclined conditions when severe accidents happen to the ship. In this paper, to investigate the characteristics of natural circulation, experiments were conducted in a symmetric loop under the inclined angle of 0~45°. A CFD model was also set up to predict the behaviors of the loop beyond the experimental scope. Total circulation flow rate decreases with the increase of inclined angle. Meanwhile one circulation is depressed while the other is enhanced, and accordingly the disparity between the branch circulations arises and increases with the increase of inclined angle. Circulation only takes place in one branch circuit at large inclined angle. Also based on the CFD model, the influences of flow resistance distribution and loop configuration on natural circulation are predicted. The numerical results show that to design the loop with the configuration of big altitude difference and small width, it is favorable to reduce the influence of inclination; however too small loop width will cause severe reduction of circulation ability at large angle inclination.

Graft polymerization of vynil monomers at carbon black surface (1)

International Nuclear Information System (INIS)

Haryono Arumbinang.

1976-01-01

Effect of aromatic condensates containing functional group on carbon black surface, effect of pH condensates on carbon black chemisorption, analysis and configuration of functional group, the crystal structure, property measurement standard, particle diameter measurement, oil adsorption, colour capacity, volatile acid content, electric resistence and the volume of the granular or carbon black dust, are given. Electron paramagnetic resonance determination of the amount of free radicals on carbon black surface, its oxidation and effects on the surface and inner structure of carbon black, and graft polymerization by radiation copolymerization, are discussed. Experiments on radiation graft copolymerization by acrylic acid, methacrylate, and glycidol methacrylate, in a vacuum condition, have been carried out. It is concluded that further research on the modification and configuration of carbon black should be developed. (author)

Early tension loss in an anterior cruciate ligament graft. A cadaver study of four tibial fixation devices.

Science.gov (United States)

Grover, Dustin M; Howell, Stephen M; Hull, Maury L

2005-02-01

The tensile force applied to an anterior cruciate ligament graft determines the maximal anterior translation; however, it is unknown whether the tensile force is transferred to the intra-articular portion of the graft and whether the intra-articular tension and maximal anterior translation are maintained shortly after ligament reconstruction. Ten cadaveric knees were reconstructed with a double-looped tendon graft. The graft was looped through a femoral fixation transducer that measured the resultant force on the proximal end of the graft. A pneumatic cylinder applied a tensile force of 110 N to the graft exiting the tibial tunnel with the knee in full extension. The graft was fixed sequentially with four tibial fixation devices (a spiked metal washer, double staples, a bioabsorbable interference screw, and a WasherLoc). Three cyclic loading treatments designed to conservatively load the graft and its fixation were applied. The combined loss in intra-articular graft tension from friction, insertion of the tibial fixation device, and three cyclic loading treatments was 50% for the spiked washer (p = 0.0004), 100% for the double staples (p < 0.0001), 64% for the interference screw (p = 0.0001), and 56% for the WasherLoc (p < 0.0001). The tension loss caused an increase in the maximal anterior translation from that of the intact knee of 2.0 mm for the spiked washer (p = 0.005), 7.8 mm for the double staples (p < 0.0001), 2.7 mm for the interference screw (p = 0.001), and 2.1 mm for the WasherLoc (p < 0.0001). The tensile force applied to a soft-tissue anterior cruciate ligament graft is not transferred intra-articularly and is not maintained during graft fixation. The loss in tension is caused by friction in the tibial tunnel and wrapping the graft around the shank of the screw of the spiked washer, insertion of the tibial fixation device, and cyclical loading of the knee. The amount of tension loss is sufficient to increase the maximal anterior translation.

[The use of labelled albumin microspheres in the study of arteriovenous shunting in varicosities of the lower limbs (author's transl)].

Science.gov (United States)

Serise, J M; Le Héron, D; Le Héron, G; Bonnet, A; Busquet, J; Basse-Cathalinat, B; Tingaud, R

1982-01-01

The greater proportion of oxygen in the blood circulating in veins of the lower limbs bought to attention the possibility of pre-capillary arteriovenous shunting. The intra-arteriel injection of Technetium labelled serum albumin microspheres enables one to quantify arteriovenous shunts greater than 25 microns. The authors made a comparative study of arterio-venous shunting by blood gases analysis and isotopic techniques in twenty patients. The results seem to deny the existence of arteriovenous shunts in the genesis of essential varicose veins in the lower limb.

Imaging findings of arteriovenous malformations involving lung and liver in hereditary hemorrhagic telangiectasia(Osler-weber-rendu disease): two cases report

Energy Technology Data Exchange (ETDEWEB)

Yi, Jeong Geun; Lee, Joo Hyuk; Seong, Su Ok [Cheongju St. Mary' s Hospital, Cheongju (Korea, Republic of)

1999-09-01

Hereditary hemorrhagic telangiectasia (HHT) or Osler-Weber-Rendu disease is an autosomal dominant disorder characterized by repeated episodes of bleeding. Multiple telangiectases consisting of thin-walled, dilated vascular channels with arteriovenous communication may involve, for example, mucocutaneous tissue, the gastrointestinal tract, and the liver, lung, and brain. We report the imaging findings of two cases of HHT involving arteriovenous malformation of both the lungs and liver, a rare condition. Chest radiography revealed a round mass, while helical CT showed a feeding artery and draining vein with arteriovenous malformation in the lung. Color Doppler sonography revealed an enlarged and tortuous hepatic artery with high systolic velocity. CT demonstrated an enlarged hepatic artery, arteriovenous shunt, and early draining hepatic vein in the liver. Celiac angiography showed arteriovenous malformation.

Imaging findings of arteriovenous malformations involving lung and liver in hereditary hemorrhagic telangiectasia(Osler-weber-rendu disease): two cases report

International Nuclear Information System (INIS)

Yi, Jeong Geun; Lee, Joo Hyuk; Seong, Su Ok

1999-01-01

Hereditary hemorrhagic telangiectasia (HHT) or Osler-Weber-Rendu disease is an autosomal dominant disorder characterized by repeated episodes of bleeding. Multiple telangiectases consisting of thin-walled, dilated vascular channels with arteriovenous communication may involve, for example, mucocutaneous tissue, the gastrointestinal tract, and the liver, lung, and brain. We report the imaging findings of two cases of HHT involving arteriovenous malformation of both the lungs and liver, a rare condition. Chest radiography revealed a round mass, while helical CT showed a feeding artery and draining vein with arteriovenous malformation in the lung. Color Doppler sonography revealed an enlarged and tortuous hepatic artery with high systolic velocity. CT demonstrated an enlarged hepatic artery, arteriovenous shunt, and early draining hepatic vein in the liver. Celiac angiography showed arteriovenous malformation

Flash pulmonary oedema after relief of haemodialysis graft stenosis.

Science.gov (United States)

Vélez-Martínez, Mariella; Weinberg, Brent D; Mishkin, Joseph D

2013-08-01

Heart failure (HF) and chronic kidney disease (CKD) are undoubtedly very much interrelated, especially in patients with end-stage renal disease (ESRD) who are dependent on renal replacement therapy. Haemodialysis (HD) is of particular interest in cardiovascular patients due to the creation of a haemodialysis vascular access and the haemodynamic changes associated with it. Adequate HD though is very dependent on a properly functioning vascular access. Unfortunately, these surgical vascular accesses are vulnerable to stenoses and occlusions. Percutaneous endovascular treatment of these stenoses is often performed and has been found to be safe and effective. Despite its frequent use, acute medical complications of this percutaneous procedure have not been well-documented. In this report, we describe a patient who developed flash pulmonary oedema after balloon angioplasty treatment of an arteriovenous graft (AVG) stenosis. Copyright © 2012 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Cerebral arteriovenous malformation in Noonan's syndrome.

OpenAIRE

Schon, F.; Bowler, J.; Baraitser, M.

1992-01-01

Noonan's syndrome involves the association of multiple congenital abnormalities including neck webbing, pectus excavatum, facial anomalies with a variety of cardiac defects. In this paper the association of Noonan's syndrome with a large cerebral arteriovenous malformation is reported. Congenital cerebrovascular abnormalities are not a recognized feature of the syndrome. The paper also reviews previous reports of neurological associations with Noonan's syndrome, the commonest being mild intel...

Management of intracranial dural arteriovenous shunts in adults

International Nuclear Information System (INIS)

Sarma, Dipanka; Brugge, Karel ter

2003-01-01

Dural arteriovenous shunts are abnormal arteriovenous communications within the dura. They are thought to be an acquired condition in adults and can present with a variety of clinical features, ranging from benign bruits to intracranial hemorrhage and neurological deficits. The presentation and natural history of these shunts is largely determined by the pattern of venous drainage. Knowledge of natural history and careful study of the angioarchitexture by angiography is therefore mandatory for correct management of these lesions. In this review, principles of management in adults and the various factors that influence treatment decisions are discussed, with a focus on endovascular therapy. Retrograde leptomeningeal or cortical venous drainage has a strong correlation with adverse clinical events and the requirement for aggressive management in this situation is highlighted. Indications for endovascular treatment, therapeutic goals, approaches and techniques are reviewed. The role of surgical treatment is also briefly discussed

Remote Sampler Demonstration Isolok Configuration Test

International Nuclear Information System (INIS)

Kelly, Steve E.

2016-01-01

The accuracy and precision of a new Isolok sampler configuration was evaluated using a recirculation flow loop. The evaluation was performed using two slurry simulants of Hanford high-level tank waste. Through testing, the capability of the Isolok sampler was evaluated. Sample concentrations were compared to reference samples that were simultaneously collected by a two-stage Vezin sampler. The capability of the Isolok sampler to collect samples that accurately reflect the contents in the test loop improved – biases between the Isolok and Vezin samples were greatly reduce for fast settling particles.

Remote Sampler Demonstration Isolok Configuration Test

Energy Technology Data Exchange (ETDEWEB)

Kelly, Steve E. [Washington River Protection Solutions, LLC, Richland, WA (United States)

2016-06-08

The accuracy and precision of a new Isolok sampler configuration was evaluated using a recirculation flow loop. The evaluation was performed using two slurry simulants of Hanford high-level tank waste. Through testing, the capability of the Isolok sampler was evaluated. Sample concentrations were compared to reference samples that were simultaneously collected by a two-stage Vezin sampler. The capability of the Isolok sampler to collect samples that accurately reflect the contents in the test loop improved – biases between the Isolok and Vezin samples were greatly reduce for fast settling particles.

Meniscal allograft transplantation. Part 1: systematic review of graft biology, graft shrinkage, graft extrusion, graft sizing, and graft fixation.

Science.gov (United States)

Samitier, Gonzalo; Alentorn-Geli, Eduard; Taylor, Dean C; Rill, Brian; Lock, Terrence; Moutzouros, Vasilius; Kolowich, Patricia

2015-01-01

To provide a systematic review of the literature regarding five topics in meniscal allograft transplantation: graft biology, shrinkage, extrusion, sizing, and fixation. A systematic literature search was conducted using the PubMed (MEDLINE), ScienceDirect, and EBSCO-CINAHL databases. Articles were classified only in one topic, but information contained could be reported into other topics. Information was classified according to type of study (animal, in vitro human, and in vivo human) and level of evidence (for in vivo human studies). Sixty-two studies were finally included: 30 biology, 3 graft shrinkage, 11 graft extrusion, 17 graft size, and 6 graft fixation (some studies were categorized in more than one topic). These studies corresponded to 22 animal studies, 22 in vitro human studies, and 23 in vivo human studies (7 level II, 10 level III, and 6 level IV). The principal conclusions were as follows: (a) Donor cells decrease after MAT and grafts are repopulated with host cells form synovium; (b) graft preservation alters collagen network (deep freezing) and causes cell apoptosis with loss of viable cells (cryopreservation); (c) graft shrinkage occurs mainly in lyophilized and gamma-irradiated grafts (less with cryopreservation); (d) graft extrusion is common but has no clinical/functional implications; (e) overall, MRI is not superior to plain radiograph for graft sizing; (f) graft width size matching is more important than length size matching; (g) height appears to be the most important factor influencing meniscal size; (h) bone fixation better restores contact mechanics than suture fixation, but there are no differences for pullout strength or functional results; and (i) suture fixation has more risk of graft extrusion compared to bone fixation. Systematic review of level II-IV studies, Level IV.

Pulmonary arteriovenous malformations: overview and transcatheter embolotherapy

International Nuclear Information System (INIS)

Pugash, R.A.

2001-01-01

The majority of pulmonary arteriovenous malformations (pAVMs) are found in people with hereditary hemorrhagic telangiectasia (HHT), a condition also known as Osler-Weber-Rendu syndrome. HHT is a clinically heterogeneous autosomal dominant disorder in which abnormal blood vessels cause bleeding and arteriovenous shunting. The 2 basic lesions of HHT - telangiectasias and arteriovenous malformations (AVMs) - are closely related. Multisystem involvement leads to a staggering array of clinical manifestations, making HHT one of medicine's less familiar 'great pretenders'. Telangiectasias are dilated blood vessels, typically located in mucocutaneous surfaces (i.e., skin, conjunctiva, respiratory tract, gastrointestinal tract, urinary tract). Small telangiectasias are simply dilated post-capillary venules, whereas larger telangiectasias are made up of dilated arterioles and venules, often with no intervening capillary. They are, in essence, diminutive AVMs. These tiny lesions are visible as punctate bright red spots on skin and mucosal surfaces (Fig. 1). Their fragility and superficial location account for the disabling epistaxis and chronic gastrointestinal bleeding, which are so common with HHT. Hematuria (caused by urothelial telangiectasias) occurs occasionally but is not a prominent feature of the disease. Although tracheobronchial telangiectasias do occur and may cause hemoptysis, severe hemoptysis is typically related to pAVM rupture. AVMs are direct artery-to-vein connections. Though larger and far more impressive radiologically than telangiectasias, AVMs are more likely to be clinically silent until they either declare themselves in a catastrophic fashion or are detected by screening tests. In contrast to telangiectasias, which are generally found in epithelial surfaces, AVMs tend to develop within organs, most commonly the lung and brain. As screening methods evolve, liver involvement with both telangiectasias and complex AVMs is being recognized with increasing

Pulmonary arteriovenous malformations: overview and transcatheter embolotherapy

Energy Technology Data Exchange (ETDEWEB)

Pugash, R.A. [Univ. of Toronto, St. Michael' s Hospital, Dept. of Medical Imaging, Toronto, Ontario (Canada)

2001-04-01

The majority of pulmonary arteriovenous malformations (pAVMs) are found in people with hereditary hemorrhagic telangiectasia (HHT), a condition also known as Osler-Weber-Rendu syndrome. HHT is a clinically heterogeneous autosomal dominant disorder in which abnormal blood vessels cause bleeding and arteriovenous shunting. The 2 basic lesions of HHT - telangiectasias and arteriovenous malformations (AVMs) - are closely related. Multisystem involvement leads to a staggering array of clinical manifestations, making HHT one of medicine's less familiar 'great pretenders'. Telangiectasias are dilated blood vessels, typically located in mucocutaneous surfaces (i.e., skin, conjunctiva, respiratory tract, gastrointestinal tract, urinary tract). Small telangiectasias are simply dilated post-capillary venules, whereas larger telangiectasias are made up of dilated arterioles and venules, often with no intervening capillary. They are, in essence, diminutive AVMs. These tiny lesions are visible as punctate bright red spots on skin and mucosal surfaces (Fig. 1). Their fragility and superficial location account for the disabling epistaxis and chronic gastrointestinal bleeding, which are so common with HHT. Hematuria (caused by urothelial telangiectasias) occurs occasionally but is not a prominent feature of the disease. Although tracheobronchial telangiectasias do occur and may cause hemoptysis, severe hemoptysis is typically related to pAVM rupture. AVMs are direct artery-to-vein connections. Though larger and far more impressive radiologically than telangiectasias, AVMs are more likely to be clinically silent until they either declare themselves in a catastrophic fashion or are detected by screening tests. In contrast to telangiectasias, which are generally found in epithelial surfaces, AVMs tend to develop within organs, most commonly the lung and brain. As screening methods evolve, liver involvement with both telangiectasias and complex AVMs is being recognized

Cyst formation after radiosurgery for brain arteriovenous malformation treated with cystoperitoneal shunt

International Nuclear Information System (INIS)

Morihiro, Yusuke; Kato, Syoichi; Imoto, Hirochika

2010-01-01

Gamma knife and CyberKnife radiosurgery are well established and less invasive treatments for arteriovenous malformation. Delayed cyst formation is a rare but well-known complication of radiosurgery for arteriovenous malformations. The optimal treatment of cysts forming after radiosurgery remains debatable. We present a case of cyst formation after radiosurgery for brain arteriovenous malformation that was treated with a cystoperitoneal shunt (C-P shunt). A 36-year-old woman presented with left hemiparesis and numbness. Computed tomography (CT) revealed intracranial hemorrhage in the right basal ganglia. Digital subtraction angiography revealed arteriovenous malformation in the brain. Intravascular embolization was performed three times and radiosurgery was performed twice, whereby complete obliteration of the nidus was achieved. Six and a half years later, routine follow-up magnetic resonance imaging revealed cyst formation, and the patient gradually developed left hemiparesis. First, we performed stereotactic cyst aspiration. This initially resulted in a reduction in the size of the cyst and disappearance of left hemiparesis, but within a short time, the cyst increased in size again and there was recurrence of hemiparesis. Therefore, an Ommaya reservoir was established; aspiration of the cyst through this reservoir brought about an initial reduction in cyst size and alleviation of symptoms; however, no further reduction in cyst size or improvement in symptoms could be achieved. Twenty months after the placement of the Ommaya reservoir, we performed a C-P shunt operation. After the operation, further reduction in the cyst size and complete symptomatic recovery were observed. (author)

Patients on hemodialysis are better served by a proximal arteriovenous fistula for long-term venous access.

LENUS (Irish Health Repository)

Sultan, Sherif

2012-11-01

Patients with end-stage renal disease should have arteriovenous fistula (AVF) formation 3 to 6 months prior to commencing hemodialysis (HD). However, this is not always possible with strained health care resources. We aim to compare autologous proximal AVF (PAVF) with distal AVF (DAVF) in patients already on HD. Primary end point is 4-year functional primary. Secondary end point is freedom from major adverse clinical events (MACEs). From January 2003 to June 2009, out of 495 AVF formations, 179 (36%) patients were already on HD. These patients had 200 AVF formations (49 DAVF vs 151 PAVF) in arms in which no previous fistula had been formed. No synthetic graft was used. Four-year primary functional patency significantly improved with PAVF (68.9% ± SD 8.8%) compared to DAVF (7.3% ± SD 4.9%; P < .0001). Five-year freedom from MACE was 85% with PAVF compared to 40% with DAVF (P < .005). Proximal AVF bestows long-term functional access with fewer complications compared to DAVF for patients already on HD.

UTERINE ARTERIOVENOUS MALFORMATION: A CASE REPORT

OpenAIRE

Chandrashekar Murthy; Kiran

2014-01-01

Uterine arteriovenous malformation (AVM) is a rare condition, with less than 100 cases reported in the literature. Despite it being rare, it is a potentially life threatening disease. This case report describes 31- year-old women who presented with abnormal uterine bleeding. Trans abdominal sonography, colour and spectral Doppler imaging was performed, diagnosis was confirmed by non- invasive MRI scan. Laparoscopic bilateral uterine artery ligation was done successfully.

[Extracorporeal membrane oxygenation in primary graft dysfunction in a paediatric double lung transplant: presentation of a case].

Science.gov (United States)

López-Cantero, M; Grisolía, A L; Vicente, R; Moreno, I; Ramos, F; Porta, J; Torregrosa, S

2014-04-01

Primary graft dysfunction is a leading cause of morbimortality in the immediate postoperative period of patients undergoing lung transplantation. Among the treatment options are: lung protective ventilatory strategies, nitric oxide, lung surfactant therapy, and supportive treatment with extracorporeal membrane oxygenation (ECMO) as a bridge to recovery of lung function or re-transplant. We report the case of a 9-year-old girl affected by cystic fibrosis who underwent double-lung transplantation complicated with a severe primary graft dysfunction in the immediate postoperative period and refractory to standard therapies. Due to development of multiple organ failure, it was decided to insert arteriovenous ECMO catheters (pulmonary artery-right atrium). The postoperative course was satisfactory, allowing withdrawal of ECMO on the 5th post-surgical day. Currently the patient survives free of rejection and with an excellent quality of life after 600 days of follow up. Copyright © 2012 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.

Percutaneous endovascular stent-graft treatment of aortic aneurysms and dissections: new techniques and initial experience

Energy Technology Data Exchange (ETDEWEB)

Lee, Do Yun; Choi, Dong Hoon; Kang, Sung Gwon; Lee, Kwang Hoon; Won, Jong Yun [Yonsei University College of Medicine, Seoul (Korea, Republic of); Kang, Sung Gwon [Chosun University College of Medicine, Gwangju (Korea, Republic of); Won, Je Whan [Aju University College of Medicine, Suwon (Korea, Republic of); Song, Ho Young [Ulsan University College of Medicine, Seoul (Korea, Republic of)

2003-01-01

To evaluate the feasibility, safety and effectiveness of a newly designed percutaneously implanted separate stent-graft (SSG) for the treatment of aortic aneurysms and dissections. Using a percutaneous technique, SSG placement (in the descending thoracic aorta in 26 cases and infrarenal abdominal aorta in 24) was attempted in 50 patients with aortic aneurysms (n=27) or dissection (n=23). All SSGs were individually constructed using self-expandable nitinol stents and a Dacron graft, and were introduced through a 12 F sheath and expanded to a diameter of 20-34 mm. In all cases, vascular access was through the femoral artery. The clinical status of each patient was monitored, and postoperative CT was performed within one week of the procedure and at 3-6 month intervals afterwards. Endovascular stent-graft deployment was technically successful in 49 of 50 patients (98%). The one failure was due to torsion of the unsupported graft during deployment. Successful exclusion of aneurysms and the primary entry tears of dissections was achieved in all but three patients with aortic dissection. All patients in whom technical success was achieved showed complete thrombosis of the thoracic false lumen or aneurysmal sac, and the overall technique success rate was 92%. In addition, sixteen patients demonstrated complete resolution of the dissected thoracic false lumen (n=9) or aneurysmal sac (n=7). Immediate post-operative complications occurred at the femoral puncture site in one patient with an arteriovenous fistula, and in two, a new saccular aneurysm developed at the distal margin of the stent. No patients died, and there was no instance of paraplegia, stroke, side-branch occlusion or infection during the subsequent mean follow-up period of 9.4 (range, 2 to 26) months. In patients with aortic aneurysm and dissection, treatment with a separate percutaneously inserted stent-graft is technically feasible, safe, and effective.

Analysis of 855 upper extremity fistulas created using a standard protocol: the role of graft extension to achieve functional status.

Science.gov (United States)

Allan, Bassan J; Perez, Enrique R; Tabbara, Marwan

2013-06-01

The Fistula First Breakthrough Initiative (FFBI) has been one of the most important national programs to help achieve considerable improvements in the care of patients on chronic hemodialysis. FFBI has helped place guidelines to push practitioners to reduce the use of tunneled central venous catheters and to increase the rate of arteriovenous fistula use in patients requiring chronic hemodialysis access. However, despite current guidelines, no specific protocols exist for the creation and management of autogenous arteriovenous fistulas and outcomes at most centers are below national benchmarks. In this study, we examine the effectiveness of a standard protocol used at our institution for the creation of autogenous upper extremity fistulas for hemodialysis access in achieving early cannulation and early removal of tunneled dialysis catheters. Our review encompasses 855 consecutive autogenous fistulas created over a 10-year period. Our findings suggest that the use of a standard protocol for creation and management of autogenous fistulas can help increase the rate of functional accesses over national benchmarks. Additionally, extension/conversion of malfunctioning fistulas to grafts appears to be an excellent method to expedite removal of a tunneled dialysis catheter with concomitant preservation of a fistula.

Non-Imaging Acoustical Properties in Monitoring Arteriovenous Hemodialysis Access. A Review

Directory of Open Access Journals (Sweden)

Anas Mohd Noor

2015-12-01

Full Text Available The limitations of the gold standard angiography technique in arteriovenous access surveillance have opened a gap for researchers to find the best way to monitor this condition with low-cost, non-invasive and continuous bedside monitoring. The phonoangiography technique has been developed prior to these limits. This measurement and monitoring technique, associated with intelligence signal processing, promises better analysis for early detection of hemodialysis access problems, such as stenosis and thrombosis. Some research groups have shown that the phonoangiography technique could identify as many as 20% of vascular diameter changes and also its frequency characteristics due to hemodialysis access problems. The frequency characteristics of these acoustical signals are presented and discussed in detail to understand the association with the stenosis level, blood flows, sensor locations, fundamental frequency bands of normal and abnormal conditions, and also the spectral energy produced. This promising technique could be used in the near future as a tool for pre-diagnosis of arteriovenous access before any further access correction by surgical techniques is required. This paper provides an extensive review of various arteriovenous access monitoring techniques based on non-imaging acoustical properties.

Adding a PECS II block for proximal arm arteriovenous access - a randomised study.

Science.gov (United States)

Quek, K H; Low, E Y; Tan, Y R; Ong, A S C; Tang, T Y; Kam, J W; Kiew, A S C

2018-05-01

Brachial plexus block is often utilised for proximal arm arteriovenous access creation. However, the medial upper arm and axilla are often inadequately anaesthetised, requiring repeated, intraoperative local anaesthetic supplementation, or conversion into general anaesthesia. We hypothesised that the addition of a PECS II block would improve anaesthesia and analgesia for proximal arm arteriovenous access surgery. In this prospective, double-blinded, randomised proof-of-concept study, 36 consenting adults with end-stage renal disease aged between 21 and 90 years received either a combined supraclavicular and PECS II block (Group PECS, n = 18), or combined supraclavicular and sham block (Group SCB, n = 18) for proximal arm arteriovenous access surgery. Primary outcome was whether patients required intraoperative local anaesthetic supplementation by the surgeon. In Group PECS, 33.3% (6/18) needed local anaesthetic supplementation vs. 100% (18/18) in Group SCB. Group SCB had three times (RR 3.0, 95% CI 1.6-5.8; P PECS required lower volume of supplemental local anaesthetic compared to Group SCB (0.0 ml, IQR 0.0-6.3 ml vs. 15.0 ml, IQR 7.4-17.8 ml; P PECS II block to a supraclavicular block improves regional anaesthesia for patients with end-stage renal disease undergoing proximal arm arteriovenous access surgery. © 2018 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Laurent series expansion of sunrise-type diagrams using configuration space techniques

International Nuclear Information System (INIS)

Groote, S.; Koerner, J.G.; Pivovarov, A.A.

2004-01-01

We show that configuration space techniques can be used to efficiently calculate the complete Laurent series ε-expansion of sunrise-type diagrams to any loop order in D-dimensional space-time for any external momentum and for arbitrary mass configurations. For negative powers of ε the results are obtained in analytical form. For positive powers of ε including the finite ε 0 contribution the result is obtained numerically in terms of low-dimensional integrals. We present general features of the calculation and provide exemplary results up to five-loop order which are compared to available results in the literature. (orig.)

Hybrid Combustion-Gasification Chemical Looping

Energy Technology Data Exchange (ETDEWEB)

Herbert Andrus; Gregory Burns; John Chiu; Gregory Lijedahl; Peter Stromberg; Paul Thibeault

2009-01-07

For the past several years Alstom Power Inc. (Alstom), a leading world-wide power system manufacturer and supplier, has been in the initial stages of developing an entirely new, ultra-clean, low cost, high efficiency power plant for the global power market. This new power plant concept is based on a hybrid combustion-gasification process utilizing high temperature chemical and thermal looping technology The process consists of the oxidation, reduction, carbonation, and calcination of calcium-based compounds, which chemically react with coal, biomass, or opportunity fuels in two chemical loops and one thermal loop. The chemical and thermal looping technology can be alternatively configured as (i) a combustion-based steam power plant with CO{sub 2} capture, (ii) a hybrid combustion-gasification process producing a syngas for gas turbines or fuel cells, or (iii) an integrated hybrid combustion-gasification process producing hydrogen for gas turbines, fuel cells or other hydrogen based applications while also producing a separate stream of CO{sub 2} for use or sequestration. In its most advanced configuration, this new concept offers the promise to become the technology link from today's Rankine cycle steam power plants to tomorrow's advanced energy plants. The objective of this work is to develop and verify the high temperature chemical and thermal looping process concept at a small-scale pilot facility in order to enable AL to design, construct and demonstrate a pre-commercial, prototype version of this advanced system. In support of this objective, Alstom and DOE started a multi-year program, under this contract. Before the contract started, in a preliminary phase (Phase 0) Alstom funded and built the required small-scale pilot facility (Process Development Unit, PDU) at its Power Plant Laboratories in Windsor, Connecticut. Construction was completed in calendar year 2003. The objective for Phase I was to develop the indirect combustion loop with CO{sub 2

Assessment of Arteriovenous Shunt Pathway Function and Hypervolemia for Hemodialysis Patients by Using Integrated Rapid Screening System

Directory of Open Access Journals (Sweden)

Wei-Ling Chen

2017-06-01

Full Text Available Currently, the hemodialysis patients received body weight measurement by themselves, vital sign checking by nursing staffs before dialysis. Whenever, the arteriovenous routes with problems doubted, the patients needed to be referred to surgeon for vascular echography checking and then to be corrected. How to integrate these three tasks in one time is a very important issue. The project proposes to combine our previous study of audio-phono angiographic technology in detecting vascular stenosis with rapid screening system to evaluate dialysis patients’ arteriovenous routes function and their status of excess body fluids: inspecting and integrating the blood pressure, body weight, and fistula function work into a rapid screening system, and using the quantization of fistula phono angiography pitch to achieve assessing arteriovenous routes. Future hoping is developed a complete integrated intelligence system by combining the arteriovenous fistula signal processing with feature extraction with wireless sensor network technology.

Epidural haematoma: pathophysiological significance of extravasation and arteriovenous shunting

International Nuclear Information System (INIS)

Habash, A.H.; Sortland, O.; Zwetnow, N.N.

1982-01-01

35 patients with epidural bleeding operated on at Rikshospitalet, Oslo, during the period 1965 - 1980 had preoperative angiography with visualization of the external carotid artery. Twenty-one patients had extravasation of contrast medium from meningeal arteries. Seventeen of the 21 had also shunting of contrast medium from meningeal arteries to meningeal or diploic veins, while 20 of the 21 also had bled from a ruptured meningeal artery at operation. It was further found that of 20 patients who deteriorated after trauma 18 had an epidural arteriovenous shunt or extravasation. Conversely, of 15 patients who improved after trauma 12 had no evidence of a shunt. The strong correlation between the clinical course and the occurrence of extravasation supports previous experimental and clinical data, indicating the epidural arteriovenous shunt to be a major factor in the pathophysiology and the outcome of epidural bleeding. (author)

Congenital pulmonary arteriovenous malformation: a rare cause of ...

African Journals Online (AJOL)

Pulmonary arteriovenous malformation (PAVM) is a rare condition in which there is abnormal connection between pulmonary arteries and veins. The disorder usually appears in late childhood or early adult life, with dyspnea on exertion, clubbing or cyanosis. We present two patients with severe cyanosis and their work-up ...

Sampling phase lock loop (PLL) with low power clock buffer

NARCIS (Netherlands)

Gao, X.; Bahai, A.; Bohsali, M.; Djabbari, A.; Klumperink, Eric A.M.; Nauta, Bram; Socci, G.

2013-01-01

A sampling phase locked loop (PLL) circuit includes a pull-up/down buffer configured to convert an oscillator reference clock into a square wave sampling control signal input to a sampling phase detector. The buffer circuit is configured to reduce power by controlling the switching of the pull-up

Embolization of spinal arteriovenous malformations

International Nuclear Information System (INIS)

Son, Mi Young; Kim, Sun Yong; Park, Bok Hwan

1990-01-01

Recently, therapeutic embolization has been advocated as the treatment of choice for spinal AVM(arteriovenous malformations). The authors review our experience with two cases of spinal AVM treated by embolization using coaxial Tracker-18 microcatheter with Latvian. The patients included a 10 year old male with glomus type and a 14 year old female with juvenile type spinal AVM revealed recanalization 5 month later. Embolization provides curative or temporary treatment for spinal AVM. After embolic occlusion, delayed reassessment with arteriography is indicated, particularly if symptoms persist or recur

A case report of spinal dural arteriovenous fistula: origins, determinants, and consequences of abnormal vascular malformations.

Science.gov (United States)

Zakhary, Sherry M; Hoehmann, Christopher L; Cuoco, Joshua A; Hitscherich, Kyle; Alam, Hamid; Torres, German

2017-06-01

A spinal dural arteriovenous fistula is an abnormally layered connection between radicular arteries and venous plexus of the spinal cord. This vascular condition is relatively rare with an incidence of 5-10 cases per million in the general population. Diagnosis of spinal dural arteriovenous fistula is differentiated by contrast-enhanced magnetic resonance angiography or structural magnetic resonance imaging, but a definitive diagnosis requires spinal angiography methods. Here, we report a case of a 67-year-old female with a spinal dural arteriovenous fistula, provide a pertinent clinical history to the case nosology, and discuss the biology of adhesive proteins, chemotactic molecules, and transcription factors that modify the behavior of the vasculature to possibly cause sensorimotor deficits.

Air Pump-Assisted Graft Centration, Graft Edge Unfolding, and Graft Uncreasing in Young Donor Graft Pre-Descemet Endothelial Keratoplasty.

Science.gov (United States)

Jacob, Soosan; Narasimhan, Smita; Agarwal, Amar; Agarwal, Athiya; A I, Saijimol

2017-08-01

To assess an air pump-assisted technique for graft centration, graft edge unfolding, and graft uncreasing while performing pre-Descemet endothelial keratoplasty (PDEK) using young donor grafts. Continuous pressurized air infusion was used for graft centration, graft edge unfolding, and graft unwrinkling. Ten eyes of 10 patients underwent PDEK with donors aged below 40 years. In all eyes, the donor scrolled into tight scrolls. In all cases, the air pump-assisted technique was effective in positioning and centering the graft accurately and in straightening infolded graft edges and smoothing out graft creases and wrinkles. Endothelial cell loss was 38.6%. Postoperative best-corrected visual acuity at 6 months was 0.66 ± 0.25 in decimal equivalent. Continuous pressurized air infusion acted as a third hand providing a continuous pressure head that supported the graft and prevented graft dislocation as well as anterior chamber collapse during intraocular maneuvering. Adequate maneuvering space was available in all cases, and bleeding, if any, was tamponaded successfully in all cases. Although very young donor grafts may be used for PDEK, they are difficult to center and unroll completely before floating against host stroma. An air pump-assisted technique using continuous pressurized air infusion allows successful final graft positioning even with very young donor corneas. It thus makes surgery easier as several key steps are made easier to handle. It additionally helps in tamponading hemorrhage during peripheral iridectomy, increasing surgical space, preventing fluctuations in the anterior chamber depth, and promoting graft adherence.

Endovascular Revascularization of Hemodialysis Thrombosed Grafts with the Hydrodynamic Thrombectomy Catheter. Our 7-Year Experience

Energy Technology Data Exchange (ETDEWEB)

Bermudez, Patrícia, E-mail: pbermude@clinic.ub.es [Clinic Hospital of Barcelona, Vascular and Interventional Radiology Unit, Diagnostic Imaging Institute (Spain); Fontseré, Nestor, E-mail: fontsere@clinic.ub.es [Clinic Hospital of Barcelona, Vascular Access Unit, Nephrologic and Urologic Diseases Clinical Institute (Spain); Mestres, Gaspar, E-mail: gmestres@clinic.ub.es [Clinic Hospital of Barcelona, Cardiovascular Diseases Institute (Spain); García-Gámez, Andres, E-mail: garciagam@clinic.ub.es; Barrufet, Marta, E-mail: barrufet@clinic.ub.es; Burrel, Marta, E-mail: mburrel@clinic.ub.es; Gilabert, Rosa, E-mail: gilabert@clinic.ub.es; Gómez, Fernando, E-mail: fegomez@clinic.ub.es; Macho, Juan, E-mail: jmmacho@clinic.ub.es [Clinic Hospital of Barcelona, Vascular and Interventional Radiology Unit, Diagnostic Imaging Institute (Spain)

2017-02-15

PurposeTo evaluate the efficacy and safety of the hydrodynamic thrombectomy catheter (AngioJet DVX) in the salvage of thrombosed hemodialysis vascular grafts.Materials and MethodsA retrospective study was designed, including all patients with occluded arteriovenous grafts treated with the AngioJet system between 2007 and 2014 in our institution. Outcomes included technical success, clinical success, complications, and primary and secondary patencies. Procedural success was defined as angiographic confirmation of flow restoration, the presence of a pulsatile thrill along the graft, and successful resumption of at least one hemodialysis session. Primary and secondary patencies after first AVG thrombectomy were calculated with Kaplan–Meier curves. Cox regression was used to determine prognostic factors of primary patency after every thrombectomy episode.ResultsA total of 149 thrombectomies were performed in 68 grafts. After thrombectomy, endovascular treatment of one or more stenosis was performed in all cases. Technical success was 93% and clinical success was 86%. Complications occurred in 7 thrombectomies, most of them were minor except for one anastomosis rupture requiring surgery. Primary and secondary patencies were 52, 41, and 23 and 76, 68, and 57% at 3, 6 and 12 months, respectively. Independent prognostic factors of poor patency after every thrombectomy episode were the presence of residual thrombus (OR 1.831, P = 0.008) and time from last thrombosis (less than 1 month; and OR 7.116, P < 0.001).ConclusionPercutaneous mechanical thrombectomy with AngioJet is a safe technique with a high-clinical success rate. The presence of residual thrombus after thrombectomy and early re-occlusions are related to poorer results.

Perkutan transluminal embolisering af pulmonale arteriovenøse misdannelser

DEFF Research Database (Denmark)

Kjeldsen, A D; Andersen, P E; Oxhøj, H

1998-01-01

A series of nine patients with pulmonary arteriovenous malformations (PAVM) treated with embolotherapy at Odense University Hospital is presented. In all patients the arterial oxygen tension increased after embolisation. PAVM causes right-to-left shunting, which may result in severe hypoxaemia, and...

Ground loops detection system in the RFX machine

International Nuclear Information System (INIS)

Bellina, F.; Pomaro, N.; Trevisan, F.

1996-01-01

RFX is a toroidal machine for the fusion research based on the RFP configuration. During the pulse, in any conductive loop close to the machine very strong currents can be induced, which may damage the diagnostics and the other instrumentation. To avoid loops, the earthing system of the machine is tree-shaped. However, an accidental contact between metallic earthed masses of the machine may give rise to an unwanted loop as well. An automatic system for the detection of ground loops in the earthing system has therefore been developed, which works continuously during shutdown intervals and between pulses. In the paper the design of the detection system is presented, together with the experimental results on prototypes. 4 refs., 3 figs., 1 tab

Prevalence of dependent loops in urinary drainage systems in hospitalized patients.

Science.gov (United States)

Danek, Gale; Gravenstein, Nikolaus; Lizdas, David E; Lampotang, Samsun

2015-01-01

The purpose of this study was to measure the prevalence and configuration of dependent loops in urinary drainage systems in hospitalized, catheterized adults. The study sample comprised 141 patients with indwelling urinary catheters; subjects were hospitalized at an academic health center in northern Florida. We measured the prevalence of dependent loops in urine drainage systems and the incidence of urine-filled dependent loops over a 3-week period. We measured the heights of the crest (H(c)), trough (H(t)), and, when urine-filled dependent loops were present, the patient-side (H(p)) and bag-side (H(b)) menisci with a laser measurement system. All variables were measured in centimeters. The majority of observed urine drainage systems (85%) contained dependent loops in the drainage tubing and 93.8% of the dependent loops contained urine. H(c) and H(t) averaged 45.1 ± 11.1 and 27 ± 16.7 cm, respectively. Meniscus height difference (H(b) - H(p)) averaged 8.2 ± 5.8 and -12.2 ± 9.9 cm when H(p) H(b) (32.7%), respectively. We found that dependent loops are extremely common in urinary drainage systems among hospitalized patients despite the manufacturer recommendations and nursing and hospital policies. Maintaining the urine drainage tubing free of dependent loops would require incorporation into nursing care priorities and workflow as inadvertent force on the tubing, for example, patient movement or nurse contact can change tubing configuration and allow excess drainage tubing to re-form a dependent loop.

Linear accelerator radiosurgery for arteriovenous malformations: Updated literature review.

Science.gov (United States)

Yahya, S; Heyes, G; Nightingale, P; Lamin, S; Chavda, S; Geh, I; Spooner, D; Cruickshank, G; Sanghera, P

2017-04-01

Arteriovenous malformations (AVMs) are the leading causing of intra-cerebral haemorrhage. Stereotactic radiosurgery (SRS) is an established treatment for arteriovenous malformations (AVM) and commonly delivered using Gamma Knife within dedicated radiosurgery units. Linear accelerator (LINAC) SRS is increasingly available however debate remains over whether it offers an equivalent outcome. The aim of this project is to evaluate the outcomes using LINAC SRS for AVMs used within a UK neurosciences unit and review the literature to aid decision making across various SRS platforms. Results have shown comparability across platforms and strongly supports that an adapted LINAC based SRS facility within a dynamic regional neuro-oncology department delivers similar outcomes (in terms of obliteration and toxicity) to any other dedicated radio-surgical platform. Locally available facilities can facilitate discussion between options however throughput will inevitably be lower than centrally based dedicated national radiosurgery units. Copyright © 2016. Published by Elsevier Ltd.

Acquired arteriovenous fistula in a grizzly bear (Ursus arctos horribilis).

Science.gov (United States)

Tuttle, Allison D; MacLean, Robert A; Linder, Keith; Cullen, John M; Wolfe, Barbara A; Loomis, Michael

2009-03-01

A captive adult male grizzly bear (Ursus arctos horribilis) was evaluated due to multifocal wounds of the skin and subcutaneous tissues sustained as a result of trauma from another grizzly bear. On presentation, one lesion that was located in the perineal region seemed to be a deep puncture with purple tissue protruding from it. This perineal wound did not heal in the same manner or rate as did the other wounds. Twenty-five days after initial detection, substantial active hemorrhage from the lesion occurred and necessitated anesthesia for examination of the bear. The entire lesion was surgically excised, which later proved curative. An acquired arteriovenous fistula was diagnosed via histopathology. Arteriovenous fistulas can develop after traumatic injury and should be considered as a potential complication in bears with nonhealing wounds.

Technique to Avoid Hemodialysis Catheter in Patients with Failing Aneurysmal Arteriovenous Fistula by Creating a Concomitant New Arteriovenous Fistula.

Science.gov (United States)

Lara, Kelly A; Chua, Rochelle Anne; Vo, Trung D

2018-05-01

Autogenous arteriovenous fistula (AVF) is the primary recommended access for hemodialysis. Long-term use will not uncommonly result in AVF aneurysmal degeneration. Aneurysm-associated complications encompass pain, skin ulceration, infection, thrombosis, cannulation difficulties, and life-threatening bleeding. Various methods to repair aneurysmal AVFs have been described. However, there may be circumstances when this is not possible and require insertion of a temporary hemodialysis catheter (HDC) until a new arteriovenous access is created. We describe a case series of creating a new simultaneous AVF while continuing to use the primary failing aneurysmal AVF to avoid placement of an HDC. Once the new AVF becomes operational, the primary aneurysmal AVF can be abandoned. Six patients underwent simultaneous new AVF creation, 4 ipsilateral, and 2 contralateral. None of the patients developed symptomatic steal syndrome or congestive heart failure. Five of 6 patients had successful usage of the new AVF, and subsequently underwent ligation and excision of the aneurysmal AVF, thus avoiding a temporary HDC. Close monitoring for skin compromise and bleeding in the aneurysmal AVF is recommended while the new AVF matures. Copyright © 2018 Elsevier Inc. All rights reserved.

Arteriovenous Malformation in Temporal Lobe Presenting as Contralateral Ocular Symptoms Mimicking Carotid-Cavernous Fistula

Directory of Open Access Journals (Sweden)

Fadzillah Mohd-Tahir

2013-01-01

Full Text Available Aim. To report a rare case of arteriovenous malformation in temporal lobe presenting as contralateral orbital symptoms mimicking carotid-cavernous fistula. Method. Interventional case report. Results. A 31-year-old Malay gentleman presented with 2-month history of painful progressive exophthalmos of his left eye associated with recurrent headache, diplopia, and reduced vision. Ocular examination revealed congestive nonpulsating 7 mm exophthalmos of the left eye with no restriction of movements in all direction. There was diplopia in left lateral gaze. Left IOP was elevated at 29 mmHg. Left eye retinal vessels were slightly dilated and tortuous. CT scan was performed and showed right temporal arteriovenous malformation with a nidus of 3.8 cm × 2.5 cm with right middle cerebral artery as feeding artery. There was dilated left superior ophthalmic vein of 0.9 mm in diameter with enlarged left cavernous sinus. MRA and carotid angiogram confirmed right temporal arteriovenous malformation with no carotid-cavernous fistula. Most of the intracranial drainage was via left cavernous sinus. His signs and symptoms dramatically improved following successful embolisation, completely resolved after one year. Conclusion. Intracranial arteriovenous malformation is rarely presented with primary ocular presentation. Early intervention would salvage the eyes and prevent patients from more disaster morbidity or fatality commonly due to intracranial haemorrhage.

A case report of spinal dural arteriovenous fistula: origins, determinants, and consequences of abnormal vascular malformations

Directory of Open Access Journals (Sweden)

Sherry M. Zakhary, DO

2017-06-01

Full Text Available A spinal dural arteriovenous fistula is an abnormally layered connection between radicular arteries and venous plexus of the spinal cord. This vascular condition is relatively rare with an incidence of 5–10 cases per million in the general population. Diagnosis of spinal dural arteriovenous fistula is differentiated by contrast-enhanced magnetic resonance angiography or structural magnetic resonance imaging, but a definitive diagnosis requires spinal angiography methods. Here, we report a case of a 67-year-old female with a spinal dural arteriovenous fistula, provide a pertinent clinical history to the case nosology, and discuss the biology of adhesive proteins, chemotactic molecules, and transcription factors that modify the behavior of the vasculature to possibly cause sensorimotor deficits.

Is a Swine Model of Arteriovenous Malformation Suitable for Human Extracranial Arteriovenous Malformation? A Preliminary Study

Energy Technology Data Exchange (ETDEWEB)

Lv, Ming-ming, E-mail: lvmingming001@163.com [Ninth People' s Hospital, Shanghai Jiao Tong University School of Medicine, Department of Oral and Maxillofacial Surgery, Shanghai Key Laboratory of Stomatology (China); Fan, Xin-dong, E-mail: fanxindong@yahoo.com.cn [Ninth People' s Hospital, Shanghai Jiao Tong University School of Medicine, Department of Radiology (China); Su, Li-xin, E-mail: sulixin1975@126.com [Ninth People' s Hospital, Shanghai Jiao Tong University School of Medicine, Department of Oral and Maxillofacial Surgery, Shanghai Key Laboratory of Stomatology (China)

2013-10-15

Objective: A chronic arteriovenous malformation (AVM) model using the swine retia mirabilia (RMB) was developed and compared with the human extracranial AVM (EAVM) both in hemodynamics and pathology, to see if this brain AVM model can be used as an EAVM model. Methods: We created an arteriovenous fistula between the common carotid artery and the external jugular vein in eight animals by using end-to-end anastomosis. All animals were sacrificed 1 month after surgery, and the bilateral retia were obtained at autopsy and performed hematoxylin and eosin staining and immunohistochemistry. Pre- and postsurgical hemodynamic evaluations also were conducted. Then, the blood flow and histological changes of the animal model were compared with human EAVM. Results: The angiography after operation showed that the blood flow, like human EAVM, flowed from the feeding artery, via the nidus, drained to the draining vein. Microscopic examination showed dilated lumina and disrupted internal elastic lamina in both RMB of model and nidus of human EAVM, but the thickness of vessel wall had significant difference. Immunohistochemical reactivity for smooth muscle actin, angiopoietin 1, and angiopoietin 2 were similar in chronic model nidus microvessels and human EAVM, whereas vascular endothelial growth factor was significant difference between human EAVM and RMB of model. Conclusions: The AVM model described here is similar to human EAVM in hemodynamics and immunohistochemical features, but there are still some differences in anatomy and pathogenetic mechanism. Further study is needed to evaluate the applicability and efficacy of this model.

Is a Swine Model of Arteriovenous Malformation Suitable for Human Extracranial Arteriovenous Malformation? A Preliminary Study

International Nuclear Information System (INIS)

Lv, Ming-ming; Fan, Xin-dong; Su, Li-xin

2013-01-01

Objective: A chronic arteriovenous malformation (AVM) model using the swine retia mirabilia (RMB) was developed and compared with the human extracranial AVM (EAVM) both in hemodynamics and pathology, to see if this brain AVM model can be used as an EAVM model. Methods: We created an arteriovenous fistula between the common carotid artery and the external jugular vein in eight animals by using end-to-end anastomosis. All animals were sacrificed 1 month after surgery, and the bilateral retia were obtained at autopsy and performed hematoxylin and eosin staining and immunohistochemistry. Pre- and postsurgical hemodynamic evaluations also were conducted. Then, the blood flow and histological changes of the animal model were compared with human EAVM. Results: The angiography after operation showed that the blood flow, like human EAVM, flowed from the feeding artery, via the nidus, drained to the draining vein. Microscopic examination showed dilated lumina and disrupted internal elastic lamina in both RMB of model and nidus of human EAVM, but the thickness of vessel wall had significant difference. Immunohistochemical reactivity for smooth muscle actin, angiopoietin 1, and angiopoietin 2 were similar in chronic model nidus microvessels and human EAVM, whereas vascular endothelial growth factor was significant difference between human EAVM and RMB of model. Conclusions: The AVM model described here is similar to human EAVM in hemodynamics and immunohistochemical features, but there are still some differences in anatomy and pathogenetic mechanism. Further study is needed to evaluate the applicability and efficacy of this model

Arteriovenous fistulae after renal biopsy: diagnosis and outcomes using Doppler ultrasound assessment.

Science.gov (United States)

Sosa-Barrios, R Haridian; Burguera, Victor; Rodriguez-Mendiola, Nuria; Galeano, Cristina; Elias, Sandra; Ruiz-Roso, Gloria; Jimenez-Alvaro, Sara; Liaño, Fernando; Rivera-Gorrin, Maite

2017-12-20

Percutaneous renal biopsy (PRB) is an important technique providing relevant information to guide diagnosis and treatment in renal disease. As an invasive procedure it has complications. Most studies up to date have analysed complications related to bleeding. We report the largest single-center experience on routine Doppler ultrasound (US) assessment post PRB, showing incidence and natural history of arteriovenous fistulae (AVF) post PRB. We retrospectively analysed 327 consecutive adult PRB performed at Ramon Cajal University Hospital between January 2011 and December 2014. All biopsies were done under real-time US guidance by a trained nephrologist. Routine Doppler mapping and kidney US was done within 24 h post biopsy regardless of symptoms. Comorbidities, full blood count, clotting, bleeding time and blood pressure were recorded at the time of biopsy. Post biopsy protocol included vitals and urine void checked visually for haematuria. Logistic regression was used to investigate links between AVF, needle size, correcting for potential confounding variables. 46,5% were kidney transplants and 53,5% were native biopsies. Diagnostic material was obtained in 90,5% (142 grafts and 154 native). Forty-seven AVF's (14.37%) were identified with routine kidney Doppler mapping, 95% asymptomatic (n = 45), 28 in grafts (18.4%) and 17 natives (9.7%) (p-value 0.7). Both groups were comparable in terms of comorbidities, passes, cylinders or biopsy yield (p-value NS). 80% were <1 cm in size and 46.6% closed spontaneously in less than 30 days (range 3-151). Larger AVF's (1-2 cm) took a mean of 52 days to closure (range 13-151). Needle size was not statistically significant factor for AVF (p-value 0.71). Contrary to historical data published, AVF's are a common complication post PRB that can be easily missed. Routine US Doppler mapping performed by trained staff is a cost-effective, non-invasive tool to diagnose and follow up AVF's, helping to assess management.

Dural arteriovenous fistula as a treatable dementia.

Science.gov (United States)

Enofe, Ikponmwosa; Thacker, Ike; Shamim, Sadat

2017-04-01

Dementia is a chronic loss of neurocognitive function that is progressive and irreversible. Although rare, dural arteriovenous fistulas (DAVFs) could present with a rapid decline in neurocognitive function with or without Parkinson-like symptoms. DAVFs represent a potentially treatable and reversible cause of dementia. Here, we report the case of an elderly woman diagnosed with a DAVF after presenting with new-onset seizures, deteriorating neurocognitive function, and Parkinson-like symptoms.

Exact one-fermion-loop contributions in (1+1)-dimensional solitons

International Nuclear Information System (INIS)

Shepard, J.R.; Price, C.E.; Ferree, T.C.

1993-01-01

We find solutions to the (1+1)-dimensional scalar-only linear σ model. A new method is used to compute one-fermion-loop contributions exactly, and agreemment with published results employing other methods is excellent. A renormalization scheme which differs from that commonly used in such calculations but is similar to that required in 1+3 dimensions is also presented. We compare ''kink'' versus ''shallow bag'' solutions, paying careful attention to the implications of the one-fermion-loop contributions for the stability of the former. We find that, for small fermion multiplicities, self-consistent shallow bag solutions are always more bound than their metastable kink counterparts. However, as the fermion multiplicity increases, shallow bags evolve into kinks which eventually are the only self-consistent configurations. This situation is qualitatively the same for the two renormalization schemes considered. When we construct ''baryons,'' each containing three fermions, the kink configuration is typically more bound than the shallow bag when one-fermion-loop contributions are included

Systemic-pulmonary arteriovenous fistula of traumatic origin: A case report

International Nuclear Information System (INIS)

Hirsch, M.; Maroko, I.; Gueron, M.; Goleman, L.

1983-01-01

Arteriovenous fistulas between the systemic circulation and the pulmonary artery are extremely rare. Continuous precordial murmur is the usual clinical sign while unilateral rib notching may be the only radiologic manifestation of this condition. Selective angiographic investigation is necessary to localize the site of such an arteriovenous (AV) fistula before surgery is performed. In a review of the literature of 15 published cases, the majority were of congenital origin, with four of these systemic-pulmonary AV fistulas of traumatic origin, of which one occurred after insertion of an intercostal catheter. We describe one case of traumatic origin 9 years after percutaneous thoracic drainage for spontaneous pneumothorax, in which transcatheter embolic occlusion of the feeding arteries of an AV fistula was attempted. The advantages and the disadvantages of the non-surgical and surgical therapeutic approaches are discussed. (orig.)

Transit-time flow measurement as a predictor of coronary bypass graft failure at one year angiographic follow-up

DEFF Research Database (Denmark)

Lehnert, Per; Møller, Christian H; Damgaard, Sune

2015-01-01

on graft vessel type, anastomatic configuration, and coronary artery size. RESULTS: Nine hundred eighty-two coronary anastomoses were performed of which 12% had signs of graft failure at one year angiographic follow-up. In internal mammary arteries (IMAs), analysis showed a 4% decrease in graft failure......BACKGROUND: Transit-time flow measurement (TTFM) is a commonly used intraoperative method for evaluation of coronary artery bypass graft (CABG) anastomoses. This study was undertaken to determine whether TTFM can also be used to predict graft patency at one year postsurgery. METHODS: Three hundred...... forty-five CABG patients with intraoperative graft flow measurements and one year angiographic follow-up were analyzed. Graft failure was defined as more than 50% stenosis including the "string sign." Logistic regression analysis was used to analyze the risk of graft failure after one year based...

Fluctuation current in superconducting loops

International Nuclear Information System (INIS)

Berger, Jorge

2012-01-01

A superconducting loop that encloses noninteger flux holds a permanent current. On the average, this current is also present above T c , and has been measured in recent years. We are able to evaluate the permanent current within the TDGL or the Kramer-Watts-Tobin models for loops of general configuration, i.e., we don't require uniform cross section, material or temperature. We can also consider situations in which the width is not negligible in comparison to the radius. Our results agree with experiments. The situations with which we deal at present include fluctuation superconductivity in two-band superconductors, equilibrium thermal fluctuations of supercurrent along a weak link, and ratchet effects.

Uterine Arteriovenous Fistula with Concomitant Pelvic Varicocele: Endovascular Embolization with Onyx-18®

Directory of Open Access Journals (Sweden)

Francesco Giurazza

2017-01-01

Full Text Available Uterine arteriovenous fistulas are rare and acquired causes of life-threatening vaginal bleeding. They usually present with intermittent menometrorrhagia in young patients in childbearing age with history of gynecological procedures on uterus. Traditional management is hysterectomy; endovascular embolization represents nowadays an alternative strategy for patients wishing to preserve fertility. Here, the endovascular approach to a 29-year-old woman affected by severe menometrorrhagia caused by a uterine arteriovenous fistula with a concomitant pelvic varicocele is reported; a bilateral uterine arteries embolization with Onyx-18 (ev3, Irvine, CA, USA has successfully resolved the fistula with clinical success.

Cranial dural arteriovenous fistula as a rare cause of tinnitus – case report

International Nuclear Information System (INIS)

Kuśmierska, Małgorzata; Gać, Paweł; Nahorecki, Artur; Szuba, Andrzej; JaŸwiec, Przemysław

2013-01-01

Tinnitus, occurring at least once in a lifetime in about 10–20% of the population, is an important clinical problem with complex etiology. Rare causes of tinnitus include cranial dural arteriovenous fistulas (DAVFs), which are usually small lesions consisting of abnormal connections between branches of dural arteries and venous sinuses or veins. Authors present a case of a 44-year-old woman with persistent, unilateral, treatment-resistant pulsatile tinnitus caused by a small dural arteriovenous fistula revealed in computed tomography angiography. Computed tomography angiography is a useful diagnostic method that in some cases allows for establishing the cause of unilateral, pulsatile tinnitus

Cranial dural arteriovenous fistula as a rare cause of tinnitus – case report

Energy Technology Data Exchange (ETDEWEB)

Kuśmierska, Małgorzata; Gać, Paweł [Department of Medical Radiology and Imaging Diagnostics, 4th Military Clinical Hospital, Wrocław (Poland); Nahorecki, Artur [Department of Internal Diseases, 4th Military Clinical Hospital, Wrocław (Poland); Szuba, Andrzej [Department of Internal Diseases, 4th Military Clinical Hospital, Wrocław (Poland); Medical University, Wrocław (Poland); JaŸwiec, Przemysław [Department of Medical Radiology and Imaging Diagnostics, 4th Military Clinical Hospital, Wrocław (Poland)

2013-07-01

Tinnitus, occurring at least once in a lifetime in about 10–20% of the population, is an important clinical problem with complex etiology. Rare causes of tinnitus include cranial dural arteriovenous fistulas (DAVFs), which are usually small lesions consisting of abnormal connections between branches of dural arteries and venous sinuses or veins. Authors present a case of a 44-year-old woman with persistent, unilateral, treatment-resistant pulsatile tinnitus caused by a small dural arteriovenous fistula revealed in computed tomography angiography. Computed tomography angiography is a useful diagnostic method that in some cases allows for establishing the cause of unilateral, pulsatile tinnitus.

Nursing care of indwelling catheter thrombolysis for acute thrombosis in the arteriovenous fistula in hemodialysis patients

International Nuclear Information System (INIS)

Gao Peizhu; Ding Wenbin; Ming Zhibing; Sun Juyun

2010-01-01

Objective: To summarize the experience of the nursing care of indwelling catheter thrombolysis for acute thrombosis in the arteriovenous fistula in eight hemodialysis patients. Methods: After breaking thrombus through indwelling catheter, both bolus injection and micro-pump continuous infusion of urokinase was employed in eight hemodialysis patients with acute thrombosis in the arteriovenous fistula. The necessary nursing measures were carried out to assist the whole therapeutic procedure. Results: All the patients could well cooperate with the procedure of indwelling catheter thrombolysis and urokinase infusion. The reopening rate of the obstructed fistula was 100%. Conclusion: Indwelling catheter thrombolysis with urokinase infusion is a simple, effective and safe treatment for acute thrombosis in the arteriovenous fistula in hemodialysis patients. In order to obtain optimal results, necessary nursing measures must be carried out. (authors)

MR Imaging of Stable Posterior Cruciate Ligament Grafts in 21 Arthroscopically Proven Cases

International Nuclear Information System (INIS)

Yoon, Young Cheol; Chung, Hye Won; Ahn, Jin Hwan

2007-01-01

To describe the magnetic resonance (MR) appearance of intact posterior cruciate ligament (PCL) grafts. Thirty-one postoperative MR examinations were performed in 21 grafts of 20 patients after PCL reconstruction. All 21 grafts were proven to be intact on second-look arthroscopic examination. Two musculoskeletal radiologists retrospectively analyzed the MR findings and reached decisions by consensus. The signal intensity (SI) of the graft on proton density-weighted and T2-weighted images, as well as the shapes, locations, and segments of increased SI were recorded. The graft thickness was also recorded and correlated to elapsed time since reconstructive surgery. The SI of the graft was high (15/31, 48%), intermediate (10/31, 32%), or low (6/31, 19%) on proton density-weighted images, and high (9/31, 29%), intermediate (6/31, 19%), or low (16/31, 52%) on T2-weighted images. The graft SI decreased significantly as postoperative time elapsed. The shape of the increased SI within the grafts was band-like (14/25, 56%) or focal (11/25, 44%). The increased SI was located in the proximal (18/25, 72%), middle (21/25, 82%), and distal (12/25, 48%) segments. In the axial plane, the location of increased SI was intrasubstance (19/25, 76%) or peripheral (10/25, 40%). A 'focal' shape of increased SI was found significantly more in Achilles tendon allografts, while a band-like shape was more frequent in autogenous double-loop hamstring tendon grafts. Graft thickness ranged from 5 15 mm. The difference in graft thickness relative to postoperative time was not statistically significant (p = 0.79). Stable PCL grafts commonly showed an increased SI at any segment or location, even though they were stable. The shape of increased SI differed according to allograft donor sites. However, SI tended to decrease as time elapsed

Effective flow performances and dialysis doses delivered with permanent catheters: a 24-month comparative study of permanent catheters versus arterio-venous vascular accesses.

Science.gov (United States)

Canaud, Bernard; Leray-Moragues, Hélène; Kerkeni, Nadia; Bosc, Jean-Yves; Martin, Katja

2002-07-01

Permanent venous catheters have emerged as a long-term vascular access option for renal replacement therapy in end-stage renal disease patients. The design and venous location of catheter devices bear intrinsic flow limitations that may negatively affect the adequacy of dialysis and the patient outcome. There is limited data comparing the long-term dialysis adequacy delivered with permanent catheters vs arterio-venous vascular accesses (AVA). To explore this problem, we conducted a prospective 24-month trial comparing the flow performances and dialysis dose (Kt/Vdp) deliveries of both access options in a group of 42 haemodialysis patients during two study phases. During the first 12 months the patients completed a treatment period by means of permanent dual silicone catheters (DualKT). Then they were transferred to an AVA (40 native arterio-venous fistulas and two PTFE grafts) and monitored for an additional 12-month period. Assessments of flow adequacy and dialysis quantification were performed monthly. Dialysis adequacy was achieved in all cases. No patient had to be transferred prematurely to the AVA because of catheter failure. Three catheters had to be replaced due to bacteraemia in three patients. The mean effective blood flow rates achieved were 316+/-3.5 ml/min and 340+/-3.3 ml/min with DualKT and AVA, respectively, for a pre-set machine blood flow of 348+/-2.2 ml/min. Recirculation rates evaluated with the 'slow blood flow' method were 8.6+/-0.6 and 12.1+/-0.8% for DualKT and AVA using mean values of the solute markers urea and creatinine. Due to the possibility of a comparison veno-venous vs arterio-venous blood circulation, a corrected arterio-venous access recirculation could be derived from the difference between the two, which was around 3%. The blood flow resistance of the DualKT was slightly higher than with AVA as indicated by venous pressure differences. Kt/Vdp delivered was 1.37+/-0.02 and 1.45+/-0.02 with DualKT and AVA access respectively. The

Endovascular Placement of an Extraluminal Femoropopliteal Bypass Graft in Human Cadavers

International Nuclear Information System (INIS)

Maynar, Manuel; Llorens, Rafael; Lopez-Sanchez, Carmen; Garcia-Martinez, Virginio; Qian Zhong; Lopera, Jorge; Castaneda, Wilfrido R.

2005-01-01

Purpose. A method to create an extraluminal femoropopliteal bypass graft using endovascular techniques was evaluated in situ on cadaver extremities in an attempt to develop a minimally invasive alternative technique for the management of infrainguinal occlusive arterial disease. Methods. The endovascular placement of an extraluminal femoropopliteal bypass graft was undertaken in 5 cadaver legs. Following percutaneous access to the popliteal artery (PA) or common femoral artery (CFA), a Rosch-Uchida needle was used to perforate the vascular wall, followed by the creation of an extraluminal tract using a looped wire and catheter. Once the desired level was reached the needle was again used to perforate the vascular wall of the proximal superficial femoral artery (SFA) or PA depending on the access used. Self-expanding expanded polytetrafluoroethylene (ePTFE) stent-grafts were then deployed to establish the extraluminal femoropopliteal bypass connecting the two arterial puncture sites. Following dilatation of the stent-graft, angiography was performed to assess the endoprostheses and to look for contrast leaks. Results. Technical success was achieved in all 5 legs. Procedure time varied from 15 to 30 min. The angiographic studies performed immediately after completion of the bypass procedure showed patency of the grafts with no evidence of kinking or leakage in any of the cases. Conclusion. This study has proved that the endovascular placement of an extraluminal femoropopliteal bypass graft in human cadaver legs using endovascular techniques under fluoroscopic control is technically feasible

Project B610 process control configuration acceptance test procedure

International Nuclear Information System (INIS)

Silvan, G.R.

1994-01-01

The purpose of this test is to verify the Westinghouse configuration of the MICON A/S Distributed Control System for project B610. The following will be verified: proper assignment and operation of all field inputs to and outputs from the MICON Termination panels; proper operation of all display data on the operator's console; proper operation of all required alarms; and proper operation of all required interlocks. The MICON A/S control system is configured to replace all the control, indication, and alarm panels now located in the Power Control Room. Nine systems are covered by this control configuration, 2736-ZB HVAC, 234-5Z HVAC, Process Vacuum, Dry Air, 291-Z Closed Loop Cooling, Building Accelerometer, Evacuation Siren, Stack CAMs, and Fire. The 2736-ZB HVAC system consists of the ventilation controls for 2736-ZB and 2736-Z as well as alarms for the emergency generators and 232-Z. The 234-5Z HVAC system is the ventilation controls for 235-5Z and 236-Z buildings. Process Vacuum covers the controls for the 26 inch vacuum system. Dry Air covers the controls for the steam and electric air dryers. The 291-Z Closed Loop Cooling system consists of the status indications and alarms for the 291-Z compressor and vacuum pump closed loop cooling system. The rest of closed loop cooling was tested earlier. The Building Accelerometer system consists of the status indications for the two seismic system accelerometers. The Evacuation Siren system includes the controls for the evacuation and take cover sirens. Stack CAMs cover the alarms for the various building ventilation stack continuous air monitors. Finally, the Fire system covers the various fire alarms now located in Room 321-A

Magnetic resonance angiography of arteriovenous malformation in the thalamus

Energy Technology Data Exchange (ETDEWEB)

Oyama, Hirofumi; Kida, Yoshihisa; Kobayashi, Tatsuya; Tanaka, Takayuki; Iwakoshi, Takayasu; Kai, Osamu; Hirose, Mitsuhiko [Komaki City Hospital, Aichi (Japan)

1993-11-01

A comparative study of magnetic resonance angiography and conventional angiography of arteriovenous malformation in the thalamus showed that both methods clearly visualized the feeding arteries: perforating branches of the posterior cerebral artery, posterior choroidal artery and lenticulostriate artery. Draining veins such as the internal cerebral vein were also demonstrated well. (author).

Magnetic Configuration Control of ITER Plasmas

International Nuclear Information System (INIS)

Albanese, R.; Artaserse, G.; Mattei, M.; Ambrosino, G.; Crisanti, F.; Tommasi, G. de; Fresa, R.; Portone, A.; Sartori, F.; Villone, F.

2006-01-01

The aim of this paper is to review the capability of the ITER Poloidal Field (PF) system of controlling the broad range of plasma configurations presently forecasted during ITER operation. The attention is focused on the axi-symmetric aspects of plasma magnetic configuration control since they pose the greatest challenges in terms of control power and they have the largest impact on machine capital cost. The paper is broadly divided in two main sections devoted, respectively, to open loop (feed-forward) and closed loop (feedback) control. In the first part of the study the PF system is assessed with respect to the initiation, ramp-up, sustained burn, ramp-down phases of the main plasma inductive scenario. The limiter-to-divertor configuration transition phase is considered in detail with the aim of assessing the PF capability to form an X-point at the lowest possible current and, therefore, to relax the thermal load on the limiter surfaces. Moreover, during the sustained burn it is important to control plasmas with a broad range of current density profiles. In the second part of the study the plasma vertical feedback control requirements are assessed in details, in particular for the high elongation configurations achievable during the early limiter-to-X point transition phase. Non-rigid plasma displacement models are used to assess the control system voltage and current requirements of different radial field control circuits obtained, for example, by connecting the outermost PF coils, some CS coils, coils sub-sections etc. At last, the main 3D effects of the vessel ports are modeled and their impact of vertical stabilization evaluated. (author)

Congenital intrahepatic arterioportal and portosystemic venous fistulae with jejunal arteriovenous malformation depicted on multislice spiral CT

International Nuclear Information System (INIS)

Chae, Eun Jin; Goo, Hyun Woo; Yoon, Chong Hyun; Kim, Seong-Chul

2004-01-01

We report a symptomatic infant with very rare congenital arterioportal and portosystemic venous fistulae in the liver. Multislice CT after partial transcatheter embolisation revealed not only the complicated vascular architecture of the lesion, but also an incidental jejunal arteriovenous malformation which explained the patient's melena. The patient underwent ligation of the hepatic artery and resection of the jejunal arteriovenous malformation. Postoperative multislice CT clearly demonstrated the success of the treatment. (orig.)

Quantifying the Cerebral Hemodynamics of Dural Arteriovenous Fistula in Transverse Sigmoid Sinus Complicated by Sinus Stenosis: A Retrospective Cohort Study.

Science.gov (United States)

Guo, W-Y; Lee, C-C J; Lin, C-J; Yang, H-C; Wu, H-M; Wu, C-C; Chung, W-Y; Liu, K-D

2017-01-01

Sinus stenosis occasionally occurs in dural arteriovenous fistulas. Sinus stenosis impedes venous outflow and aggravates intracranial hypertension by reversing cortical venous drainage. This study aimed to analyze the likelihood of sinus stenosis and its impact on cerebral hemodynamics of various types of dural arteriovenous fistulas. Forty-three cases of dural arteriovenous fistula in the transverse-sigmoid sinus were reviewed and divided into 3 groups: Cognard type I, type IIa, and types with cortical venous drainage. Sinus stenosis and the double peak sign (occurrence of 2 peaks in the time-density curve of the ipsilateral drainage of the internal jugular vein) in dural arteriovenous fistula were evaluated. "TTP" was defined as the time at which a selected angiographic point reached maximum concentration. TTP of the vein of Labbé, TTP of the ipsilateral normal transverse sinus, trans-fistula time, and trans-stenotic time were compared across the 3 groups. Thirty-six percent of type I, 100% of type IIa, and 84% of types with cortical venous drainage had sinus stenosis. All sinus stenosis cases demonstrated loss of the double peak sign that occurs in dural arteriovenous fistula. Trans-fistula time (2.09 seconds) and trans-stenotic time (0.67 seconds) in types with cortical venous drainage were the most prolonged, followed by those in type IIa and type I. TTP of the vein of Labbé was significantly shorter in types with cortical venous drainage. Six patients with types with cortical venous drainage underwent venoplasty and stent placement, and 4 were downgraded to type IIa. Sinus stenosis indicated dysfunction of venous drainage and is more often encountered in dural arteriovenous fistula with more aggressive types. Venoplasty ameliorates cortical venous drainage in dural arteriovenous fistulas and serves as a bridge treatment to stereotactic radiosurgery in most cases. © 2017 by American Journal of Neuroradiology.

Graft-Sparing Strategy for Thoracic Prosthetic Graft Infection.

Science.gov (United States)

Uchino, Gaku; Yoshida, Takeshi; Kakii, Bunpachi; Furui, Masato

2018-04-01

 Thoracic prosthetic graft infection is a rare but serious complication with no standard management. We reported our surgical experience on graft-sparing strategy for thoracic prosthetic graft infection.  This study included patients who underwent graft-sparing surgery for thoracic prosthetic graft infection at Matsubara Tokushukai Hospital in Japan from January 2000 to October 2017.  There were 17 patients included in the analyses, with a mean age at surgery of 71.0 ± 10.5 years; 11 were men. In-hospital mortality was observed in five patients (29.4%).  Graft-sparing surgery for thoracic prosthetic graft infection is an alternative option particularly for early graft infection after hemiarch replacement. Georg Thieme Verlag KG Stuttgart · New York.

Outcomes of Prosthetic Hemodialysis Grafts after Deployment of Bare Metal versus Covered Stents at the Venous Anastomosis

Energy Technology Data Exchange (ETDEWEB)

Kim, Charles Y., E-mail: charles.kim@duke.edu; Tandberg, Daniel J.; Rosenberg, Michael D.; Miller, Michael J.; Suhocki, Paul V.; Smith, Tony P. [Duke University Medical Center, Division of Vascular and Interventional Radiology (United States)

2012-08-15

Purpose: To compare postintervention patency rates after deployment of bare metal versus covered stents across the venous anastomosis of prosthetic arteriovenous (AV) grafts. Methods: Review of our procedural database over a 6 year period revealed 377 procedures involving stent deployment in an AV access circuit. After applying strict inclusion criteria, our study group consisted of 61 stent deployments in 58 patients (median age 58 years, 25 men, 33 women) across the venous anastomosis of an upper extremity AV graft circuit that had never been previously stented. Both patent and thrombosed AV access circuits were retrospectively analyzed. Within the bare metal stent group, 20 of 32 AV grafts were thrombosed at initial presentation compared to 18 of 29 AV grafts in the covered stent group. Results: Thirty-two bare metal stents and 29 covered stents were deployed across the venous anastomosis. The 3, 6, and 12 months primary access patency rates for bare metal stents were not significantly different than for covered stents: 50, 41, and 22 % compared to 59, 52, and 29 %, respectively (p = 0.21). The secondary patency rates were also not significantly different: 78, 78, and 68 % for bare metal stents compared to 76, 69, and 61 % for covered stents, respectively (p = 0.85). However, covered stents demonstrated a higher primary stent patency rate than bare metal stents: 100, 85, and 70 % compared to 75, 67, and 49 % at 3, 6, and 12 months (p < 0.01). Conclusion: The primary and secondary access patency rates after deployment of bare metal versus covered stents at the venous anastomosis were not significantly different. However, bare metal stents developed in-stent stenoses significantly sooner.

Outcomes of Prosthetic Hemodialysis Grafts after Deployment of Bare Metal versus Covered Stents at the Venous Anastomosis

International Nuclear Information System (INIS)

Kim, Charles Y.; Tandberg, Daniel J.; Rosenberg, Michael D.; Miller, Michael J.; Suhocki, Paul V.; Smith, Tony P.

2012-01-01

Purpose: To compare postintervention patency rates after deployment of bare metal versus covered stents across the venous anastomosis of prosthetic arteriovenous (AV) grafts. Methods: Review of our procedural database over a 6 year period revealed 377 procedures involving stent deployment in an AV access circuit. After applying strict inclusion criteria, our study group consisted of 61 stent deployments in 58 patients (median age 58 years, 25 men, 33 women) across the venous anastomosis of an upper extremity AV graft circuit that had never been previously stented. Both patent and thrombosed AV access circuits were retrospectively analyzed. Within the bare metal stent group, 20 of 32 AV grafts were thrombosed at initial presentation compared to 18 of 29 AV grafts in the covered stent group. Results: Thirty-two bare metal stents and 29 covered stents were deployed across the venous anastomosis. The 3, 6, and 12 months primary access patency rates for bare metal stents were not significantly different than for covered stents: 50, 41, and 22 % compared to 59, 52, and 29 %, respectively (p = 0.21). The secondary patency rates were also not significantly different: 78, 78, and 68 % for bare metal stents compared to 76, 69, and 61 % for covered stents, respectively (p = 0.85). However, covered stents demonstrated a higher primary stent patency rate than bare metal stents: 100, 85, and 70 % compared to 75, 67, and 49 % at 3, 6, and 12 months (p < 0.01). Conclusion: The primary and secondary access patency rates after deployment of bare metal versus covered stents at the venous anastomosis were not significantly different. However, bare metal stents developed in-stent stenoses significantly sooner.

Pulmonary Arteriovenous Fistula: Clinical and Histologic Spectrum of Four Cases

Directory of Open Access Journals (Sweden)

Soomin Ahn

2016-09-01

Full Text Available Pulmonary arteriovenous fistula (PAVF is abnormally dilated vessels that provide a right-to-left shunt between pulmonary artery and pulmonary vein and is clinically divided into simple and complex type. Here, we report four cases of surgically resected sporadic PAVFs presenting various clinical and histologic spectrums. Cases 1 (a 57-old-female and 2 (a 54-old-female presented as incidentally identified single aneurysmal fistulas and the lesions were surgically removed without complication. On the other hand, case 3 (an 11-old-male showed diffuse dilated vascular sacs involving both lungs and caused severe hemodynamic and pulmonary dysfunction. Embolization and surgical resection of the main lesion failed to relieve the symptoms. Case 4 (a 36-old-male had a localized multiloculated cyst clinically mimicking congenital cystic adenomatoid malformation. Microscopically, the lesion consisted of dilated thick vessels, consistent with the diagnosis of fistulous arteriovenous malformation/hemangioma.

RASA1 analysis guides management in a family with capillary malformation-arteriovenous malformation.

Science.gov (United States)

Flore, Leigh Anne; Leon, Eyby; Maher, Tom A; Milunsky, Jeff M

2012-06-01

Capillary malformation-arteriovenous malformation (CM-AVM; MIM 60354) is an autosomal dominant disorder characterized by multifocal cutaneous capillary malformations, often in association with fast-flow vascular lesions, which may be cutaneous, subcutaneous, intramuscular, intraosseus, or cerebral arteriovenous malformations or arteriovenous fistulas. CM-AVM results from heterozygous mutations in the RASA1 gene. Capillary malformations of the skin are common, and clinical examination alone may not be able to definitively diagnose-or exclude- CM-AVM. We report a family in which the proband was initially referred for a genetic evaluation in the neonatal period because of the presence of a cardiac murmur and minor dysmorphic features. Both he and his mother were noted to have multiple capillary malformations on the face, head, and extremities. Echocardiography revealed dilated head and neck vessels and magnetic resonance imaging and angiography of the brain revealed a large infratentorial arteriovenous fistula, for which he has had two embolization procedures. RASA1 sequence analysis revealed a heterozygous mutation, confirming his diagnosis of CM-AVM. We established targeted mutation analysis for the proband's mother and sister, the latter of whom is a healthy 3-year-old whose only cutaneous finding is a facial capillary malformation. This revealed that the proband's mother is also heterozygous for the RASA1 mutation, but his sister is negative. Consequently, his mother will undergo magnetic resonance imaging and angiography screening for intracranial and spinal fast-flow lesions, while his sister will require no imaging or serial evaluations. Targeted mutation analysis has been offered to additional maternal family members. This case illustrates the benefit of molecular testing in diagnosis and making screening recommendations for families with CM-AVM.

Extension of loop quantum gravity to f(R) theories.

Science.gov (United States)

Zhang, Xiangdong; Ma, Yongge

2011-04-29

The four-dimensional metric f(R) theories of gravity are cast into connection-dynamical formalism with real su(2) connections as configuration variables. Through this formalism, the classical metric f(R) theories are quantized by extending the loop quantization scheme of general relativity. Our results imply that the nonperturbative quantization procedure of loop quantum gravity is valid not only for general relativity but also for a rather general class of four-dimensional metric theories of gravity.

A LabVIEW model incorporating an open-loop arterial impedance and a closed-loop circulatory system.

Science.gov (United States)

Cole, R T; Lucas, C L; Cascio, W E; Johnson, T A

2005-11-01

While numerous computer models exist for the circulatory system, many are limited in scope, contain unwanted features or incorporate complex components specific to unique experimental situations. Our purpose was to develop a basic, yet multifaceted, computer model of the left heart and systemic circulation in LabVIEW having universal appeal without sacrificing crucial physiologic features. The program we developed employs Windkessel-type impedance models in several open-loop configurations and a closed-loop model coupling a lumped impedance and ventricular pressure source. The open-loop impedance models demonstrate afterload effects on arbitrary aortic pressure/flow inputs. The closed-loop model catalogs the major circulatory waveforms with changes in afterload, preload, and left heart properties. Our model provides an avenue for expanding the use of the ventricular equations through closed-loop coupling that includes a basic coronary circuit. Tested values used for the afterload components and the effects of afterload parameter changes on various waveforms are consistent with published data. We conclude that this model offers the ability to alter several circulatory factors and digitally catalog the most salient features of the pressure/flow waveforms employing a user-friendly platform. These features make the model a useful instructional tool for students as well as a simple experimental tool for cardiovascular research.

A case report of spinal dural arteriovenous fistula: origins, determinants, and consequences of abnormal vascular malformations

OpenAIRE

Zakhary, Sherry M.; Hoehmann, Christopher L.; Cuoco, Joshua A.; Hitscherich, Kyle; Alam, Hamid; Torres, German

2017-01-01

A spinal dural arteriovenous fistula is an abnormally layered connection between radicular arteries and venous plexus of the spinal cord. This vascular condition is relatively rare with an incidence of 5–10 cases per million in the general population. Diagnosis of spinal dural arteriovenous fistula is differentiated by contrast-enhanced magnetic resonance angiography or structural magnetic resonance imaging, but a definitive diagnosis requires spinal angiography methods. Here, we report a cas...

Cardiac failure due to arteriovenous fistula with brachiocephalic stenosis: a gated heart case study

International Nuclear Information System (INIS)

Abel, G.; Irish, A.; Henderson, A.; Lenzo, N.

2003-01-01

Full text: There are numerous causes of cardiac failure of which the commonest in our community include ischaemic cardiomyopathy, post-viral cardiomyopathy, alcohol-induced cardiomyopathy and drug-induced cardiomyopathy. All these entities cause low output cardiac failure however high output cardiac failure is also well recognised. This includes heart failure related to such conditions as hyperthyroidism, anaemia, pregnancy, beri-beri, and Paget's disease. A rare cause of high output cardiac failure is an arteriovenous fistula. We present an unusual case of a patient with end-stage renal failure on haemodialysis who developed extensive dilatation of their left arm arteriovenous fistula secondary to bachiocephalic vein stenosis. The labelled red blood cell gated heart blood pool study demonstrated decreased left ventricular function and extensive pooling of blood within the tortuous dilated left arm vessels. A follow-up study post-ligation of the arteriovenous fistula showed improvement of the left ventricular ejection fraction. The associated contrast venography findings are also demonstrated. Copyright (2003) The Australian and New Zealand Society of Nuclear Medicine Inc

Long-Term Follow-up After Embolization of Pulmonary Arteriovenous Malformations with Detachable Silicone Balloons

International Nuclear Information System (INIS)

Andersen, Poul Erik; Kjeldsen, Anette D.

2008-01-01

Long-term follow-up results after embolization of 13 pulmonary arteriovenous malformations in 10 patients by use of 14 detachable silicone balloons are given. Patients were followed for a mean of 99 months (range, 63-123 months) with chest x-rays and for a mean of 62 months (range, 3-101 months) with pulmonary angiography. Fifty-four percent of the balloons were deflated at latest radiographic chest film follow-up, but at pulmonary angiographic follow-up all embolized malformations were without flow irrespective of whether or not the balloons were visible. Detachable silicone balloons are not available anymore, but use of these balloons for embolization of pulmonary arteriovenous malformations has been shown to be a safe and precise method, with immediate occlusion of the feeding artery and with long-lasting occlusion, even though many balloons deflate with time, leaving a fibrotic scar replacing the pulmonary arteriovenous malformation. No case of recanalization has been discovered, and these results seem to justify a reduced number of controls of these balloon-embolized malformations

Radiological evaluation with Doppler sonography and multidetector CT angiography in congenital hepatic arteriovenous malformation in a newborn

Energy Technology Data Exchange (ETDEWEB)

Adaletli, Ibrahim; Kurugoglu, Sebuh; Kilic, Fahrettin [Istanbul University, Department of Radiology, Cerrahpasa Medical Faculty (Turkey); Senyuz, Osman F. [Istanbul University, Department of Paediatric Surgery, Cerrahpasa Medical Faculty (Turkey); Dervisoglu, Sergulen [Istanbul University, Department of Pathology, Cerrahpasa Medical Faculty (Turkey)

2006-11-15

Although hepatic arteriovenous malformations are rarely reported, they frequently have life-threatening complications such as cardiac failure and are associated with a high mortality rate. Consequently, accurate prenatal and early postnatal diagnosis is important and therapeutic procedures depend on the imaging features. We report the early postnatal sonographic, Doppler sonographic, multidetector CT and CT angiography findings of a congenital hepatic arteriovenous malformation in a newborn. (orig.)

Radiological evaluation with Doppler sonography and multidetector CT angiography in congenital hepatic arteriovenous malformation in a newborn

International Nuclear Information System (INIS)

Adaletli, Ibrahim; Kurugoglu, Sebuh; Kilic, Fahrettin; Senyuz, Osman F.; Dervisoglu, Sergulen

2006-01-01

Although hepatic arteriovenous malformations are rarely reported, they frequently have life-threatening complications such as cardiac failure and are associated with a high mortality rate. Consequently, accurate prenatal and early postnatal diagnosis is important and therapeutic procedures depend on the imaging features. We report the early postnatal sonographic, Doppler sonographic, multidetector CT and CT angiography findings of a congenital hepatic arteriovenous malformation in a newborn. (orig.)

Blood pressure shifts resulting from a concealed arteriovenous fistula associated with an iliac aneurysm: a case report.

Science.gov (United States)

Doi, Shintaro; Motoyama, Yoshiaki; Ito, Hiromi

2016-01-01

A solitary iliac aneurysm (SIA) is more uncommon than an abdominal aortic aneurysm. The aneurysm is located in the deep pelvis and is diagnosed when it reaches a large size with symptoms of compression around adjacent structures and organs or when it ruptures. A definite diagnosis of an arteriovenous fistula (AVF) associated with a SIA is difficult preoperatively because there might not be enough symptoms and time for diagnosis. Here, we present a patient with asymptomatic rupture of SIA into the common iliac vein with characteristic blood pressure shifts. A 41-year-old man with a huge SIA underwent aortobifemoral graft replacement. Preoperatively, his blood pressure showed characteristic shifts for one or two heartbeats out of five beats, indicating that an AVF was present and that the shunt was about to having a high flow. During surgery, an AVF associated with the SIA was found to be concealed owing to compression from the huge iliac artery aneurysm, and the shunt showed a high flow, resulting in shock during the surgery. No complications were noted after aortobifemoral graft replacement. Postoperatively, we noted an enhanced paravertebral vein on computed tomography (CT), which indicated the presence of an AVF. Definite diagnosis of an AVF offers advantages in surgical and anesthetic management. We emphasize that a large SIA can push the iliac vein and occlude an AVF laceration, concealing the enhancement of the veins in the arterial phase on CT. Blood pressure shifts might predict the existence of a concealed AVF that has a large shunt. Even if the vena cava and the iliac veins are not enhanced on CT, anesthesiologists should carefully determine whether their distal branches are enhanced.

Paraspinal arteriovenous malformation Onyx embolization via an Ascent balloon.

Science.gov (United States)

Martínez-Galdámez, Mario; Rodriguez-Arias, Carlos A; Utiel, Elena; Arreba, Emilio; Gonzalo, Miguel; Arenillas, Juan F

2014-04-01

Purely extradural lumbar spinal arteriovenous malformations (AVMs) are rare lesions that have diverse presentations and imaging features. The treatment of a symptomatic high flow paraspinal AVM with multiple feeders remains a challenge. We report the first use of an Ascent balloon (dual lumen balloon catheter) to deliver Onyx with excellent penetration to a paraspinal AVM.

A kinematic view of loop closure.

Science.gov (United States)

Coutsias, Evangelos A; Seok, Chaok; Jacobson, Matthew P; Dill, Ken A

2004-03-01

We consider the problem of loop closure, i.e., of finding the ensemble of possible backbone structures of a chain segment of a protein molecule that is geometrically consistent with preceding and following parts of the chain whose structures are given. We reduce this problem of determining the loop conformations of six torsions to finding the real roots of a 16th degree polynomial in one variable, based on the robotics literature on the kinematics of the equivalent rotator linkage in the most general case of oblique rotators. We provide a simple intuitive view and derivation of the polynomial for the case in which each of the three pair of torsional axes has a common point. Our method generalizes previous work on analytical loop closure in that the torsion angles need not be consecutive, and any rigid intervening segments are allowed between the free torsions. Our approach also allows for a small degree of flexibility in the bond angles and the peptide torsion angles; this substantially enlarges the space of solvable configurations as is demonstrated by an application of the method to the modeling of cyclic pentapeptides. We give further applications to two important problems. First, we show that this analytical loop closure algorithm can be efficiently combined with an existing loop-construction algorithm to sample loops longer than three residues. Second, we show that Monte Carlo minimization is made severalfold more efficient by employing the local moves generated by the loop closure algorithm, when applied to the global minimization of an eight-residue loop. Our loop closure algorithm is freely available at http://dillgroup. ucsf.edu/loop_closure/. Copyright 2004 Wiley Periodicals, Inc. J Comput Chem 25: 510-528, 2004

ac power control in the Core Flow Test Loop

International Nuclear Information System (INIS)

McDonald, D.W.

1980-01-01

This work represents a status report on a development effort to design an ac power controller for the Core Flow Test Loop. The Core Flow Test Loop will be an engineering test facility which will simulate the thermal environment of a gas-cooled fast-breeder reactor. The problems and limitations of using sinusoidal ac power to simulate the power generated within a nuclear reactor are addressed. The transformer-thyristor configuration chosen for the Core Flow Test Loop power supply is presented. The initial considerations, design, and analysis of a closed-loop controller prototype are detailed. The design is then analyzed for improved performance possibilities and failure modes are investigated at length. A summary of the work completed to date and a proposed outline for continued development completes the report

Reshaping Human Antibodies: Grafting an Antilysozyme Activity

Science.gov (United States)

Verhoeyen, Martine; Milstein, Cesar; Winter, Greg

1988-03-01

The production of therapeutic human monoclonal antibodies by hybridoma technology has proved difficult, and this has prompted the ``humanizing'' of mouse monoclonal antibodies by recombinant DNA techniques. It was shown previously that the binding site for a small hapten could be grafted from the heavy-chain variable domain of a mouse antibody to that of a human myeloma protein by transplanting the hypervariable loops. It is now shown that a large binding site for a protein antigen (lysozyme) can also be transplanted from mouse to human heavy chain. The success of such constructions may be facilitated by an induced-fit mechanism.

Myocardial abscess as a complication of an infected arteriovenous fistula: autopsy report

Directory of Open Access Journals (Sweden)

Cristiane Rúbia Ferreira

2011-09-01

Full Text Available Myocardial abscess is a severe and life-threatening infectious complication thatis commonly but not exclusively associated with infective endocarditis. It mayalso be developed in necrotic myocardial tissue, post trauma, in septic burnpatients, in transplanted heart, in ventricular aneurysm and post angioplasty.Patients on hemodialysis are prone to bacteremia, and infectious complicationsoccur in 48-73% of cases. Myocardial abscess is a rare complication of aninfected arteriovenous fistula. We present an autopsy report of a hemodialysispatient who had an arteriovenous fistula with a polytetrafluoroethylene graftwhere a local infection developed. The patient presented with fever and toxemia.On post-admission day 2, he unexpectedly suffered sudden cardiopulmonaryarrest and died. The autopsy revealed a myocardial abscess, near a branch ofthe left coronary artery, with septic embolism.

Arteriovenous thrombosis in chronic renal failure patients receving renal replacement therapy

International Nuclear Information System (INIS)

Shoaib, M.; Naz, A.

2008-01-01

To determine the frequency of thrombotic complications and to identify factors associated with arteriovenous thrombosis in patients of chronic renal failure receiving renal replacement therapy. Of the 3000 patients evaluated, 61 End Stage Renal Disease (ESRD) patients on regular dialysis, having recent renal transplant, were selected for the study after informed consent. These patients had arteriovenous thrombosis with temporary central lines thrombosis and vascular access problems. Cases of congenital or acquired thrombotic disorders, e.g. with malignancy, DIC, liver disease, systemic lupus erythematosus or other immunologic diseases, pregnancy or women using oral contraceptives, were excluded. Similarly, patients taking any type of anticoagulant therapy during the preceding one week were not included in the study. Findings were recorded in a structured questionnaire. Laboratory analysis was done after clinical and radiological evaluation. Thrombophilia screening included antithrombin, protein C, protein S deficiencies and lupus anticoagulant. Forty-seven out of 61 patients selected were positive for thrombophilia screening with protein C deficiency in 26.2%, protein S deficiency in 16.3%, antithrombin in 5%, lupus anticoagulant in 13.1% and combined deficiency was observed in 16.3%. Of the 3000 patients, 61 with frequency of 2% were found to be deficient in one or had combined deficiency of these. Thus, the study of ESRD patients presenting with arteriovenous thromboembolism emphasizes the need to reconsider the perception that this clinical entity is rare and requires further studies. (author)

Congenital hepatic arteriovenous fistula with intrahepatic portosystemic shunt and aortic stenosis in a dog

International Nuclear Information System (INIS)

Koide, K.; Koide, Y.; Wada, Y.; Nakaniwa, S.; Yamane, Y.

2004-01-01

Examination of a 2-month-old male golden retriever presented to the hospital revealed malnutrition, ascites, cardiac murmur and hyperammonemia. Identification of subaortic stenosis and hepatic arteriovenous fistula was made through ultrasonography and angiocardiography. In addition, intrasurgical mesenteric portography showed an intrahepatic portosystemic shunt. The dog did not show portal hypertension and secondary multiple extrahepatic portosystemic shunts. Surgical correction was attempted after medical treatment. The hepatic artery branch which was connected to the hepatic arteriovenous fistula was separated, and completely ligated using silk ligature. However, the separation of the intrahepatic shunt blood vessel was unsuccessful and the dog died 15 hr postoperatively

Venous hemodynamics of arteriovenous meningeal fistulas in the posterior cranial fossa

International Nuclear Information System (INIS)

Brainin, M.; Samec, P.

1983-01-01

The etiology of arteriovenous meningeal fistulas (AVMFs) of the posterior fossa often remains unclear. Analyses of three personal cases, however, suggest a change in venous hemodynamics due to a primary lesion, the cases being of sinus thrombosis, intracerebral abcess with oedema and arteriovenous malformation. It is suggested that increase of venous pressure in the posterior fossa leads to increased drainage and, consequently, to dilatation of infratentorial veins and of meningeal branches of the external carotid and vertebral artery. Clinical findings and anatomical facts underlying AVMF lesions tend to confirm the view that the concept of a congenital malformation decompensating with age cannot be upheld for all AVMFs, especially when located in the posterior fossa and when clinical symptoms arise in middle age. It is proposed that a pressure activated mechanism of growth results in widening of normally insignificantly small dural vessels. (orig.)

Radiation dermatitis after spinal arteriovenous malformation embolization: case report

International Nuclear Information System (INIS)

Carstens, G.J.; Horowitz, M.B.; Purdy, P.D.; Pandya, A.G.

1996-01-01

Few cases of radiation injury related to lengthy interventional neuroradiologic procedures have been reported, although concern has been heightened, as evidenced by a 1994 FDA Public Health Advisory. We report a case of radiation-induced dermatitis in a patient undergoing multiple diagnostic and embolization procedures for treatment of a spinal arteriovenous malformation. (orig.). With 2 figs

Skin graft

Science.gov (United States)

Skin transplant; Skin autografting; FTSG; STSG; Split thickness skin graft; Full thickness skin graft ... donor site. Most people who are having a skin graft have a split-thickness skin graft. This takes ...

Evolution of skin grafting for treatment of burns: Reverdin pinch grafting to Tanner mesh grafting and beyond.

Science.gov (United States)

Singh, Mansher; Nuutila, Kristo; Collins, K C; Huang, Anne

2017-09-01

Skin grafting is the current standard care in the treatment of full thickness burns. It was first described around 1500 BC but the vast majority of advancements have been achieved over the past 200 years. An extensive literature review was conducted on Pubmed, Medline and Google Scholar researching the evolution of skin grafting techniques. The authors concentrated on the major landmarks of skin grafting and also provide an overview of ongoing research efforts in this field. The major innovations of skin grafting include Reverdin pinch grafting, Ollier grafting, Thiersch grafting, Wolfe grafting, Padgett dermatome and modifications, Meek-wall microdermatome and Tanner mesh grafting. A brief description of the usage, advantages and limitations of each technique is included in the manuscript. Skin grafting technique have evolved significantly over past 200 years from Reverdin pinch grafting to modern day meshed skin grafts using powered dermatome. Increasing the expansion ratio and improving the cosmetic and functional outcome are the main focus of ongoing skin grafting research and emerging techniques (such as Integra ® , Recell ® , Xpansion ® ) are showing promise. Copyright © 2017 Elsevier Ltd and ISBI. All rights reserved.

Dissociated Structure of Dislocation Loops with Burgers Vector alpha in Electron-Irradiated Cu-Ni

DEFF Research Database (Denmark)

Bilde-Sørensen, Jørgen; Leffers, Torben; Barlow, P.

1977-01-01

The rectangular dislocation loops with total Burgers vector a100 which are formed in Cu-Ni alloys during 1 MeV electron irradiation at elevated temperatures have been examined by weak-beam electron microscopy. The loop edges were found to take up a Hirth-lock configuration, dissociating into two ...

An Unusual Case Of Urinary Bladder Arteriovenous Malformation

LENUS (Irish Health Repository)

Gnanappiragasam, D

2016-07-01

A 45-year-old male presented with haematuria and urinary frequency. Computed Tomography (CT) urogram revealed gross thickening of the left bladder wall. Histology showed large vessels cuffed by eosinophonilic material suggestive of urinary bladder arteriovenous malformation (AVM). No further intervention was carried out as symptoms resolve after the resection. Follow up rigid cystoscopy and CT at 3 months showed resolution of all visible pathology and no evidence of recurrence.

Commissioning of closed loop controls at CPP, HWP, Manuguru (Paper No. 3.5)

International Nuclear Information System (INIS)

Basu, Sukumar; Narasimham, P.L.

1992-01-01

The captive power plant (CPP) for Heavy Water Plant, Manuguru is equipped with 3x265 T/hr steam capacity boilers. The control system is built around ASEA master hardware for sequence interlocks, closed loop control, and data acquisition functions. This paper describes the configuration of the system hardware, the steps carried out during commissioning of closed loop controls in distributed digital control systems and also the problems faced during the commissioning of closed loops. (author). 3 figs

3D DD modelling of the prismatic loops and dislocations interaction in pure iron

International Nuclear Information System (INIS)

Novokshanov, R.; Roberts, S.

2007-01-01

Full text of publication follows: Neutron irradiation can increase the yield stress and reduce the ductility of metals. These effects are mainly caused by the interaction of dislocations with damage produced during irradiation. In iron irradiated with fast neutrons the damage takes the form of 1/2 and 1/2 prismatic dislocation loops (the size of the loops varies from 2 nm to 20 nm depending on the dose of irradiation). The interaction between such loops and dislocations is the subject of this research. 3D dislocation dynamics simulations have been carried out to model the interaction between prismatic loops and dis- locations in pure iron subject to uniaxial loading conditions. The primary goal was to understand the mechanism of interaction of a a/2 loop and a mobile dislocation. The simulations have shown a complicated 3D interaction resulting in either bowing around an obstacle (prismatic loop, Orowan mechanism) or cutting it through, carrying part of the loop away and leaving the other part behind. Cross-slip can be important, in a manner depending on the type of mobile dislocation, size, type and orientation of prismatic loop. The secondary goal was to investigate the dependence of the critical stress needed for dislocations to overcome the obstacles as a function of: size of loops, initial separation between loops, the direction of motion of the mobile dislocation and its type (pure edge or screw), and type of a loop (interstitial or vacancy). Many different configurations have been simulated. The size of the loops was varied from 10 nm to 100 nm; the separation between the loops in a row was varied from one to four loop diameters; the distance between the glide plane and the loop plane was varied from 0 to 20 nm. The glide plane of the mobile dislocation was either perpendicular to and or inclined to the loop plane. The results show a strong dependence of the critical stress on the size of the loops and the initial configuration. (authors)

Duplex sonography in the planning and evaluation of arteriovenous fistulae for haemodialysis

International Nuclear Information System (INIS)

Kerr, S.F.; Krishan, S.; Lapham, R.C.; Weston, M.J.

2010-01-01

This paper describes how to perform duplex sonography in the planning and evaluation of arteriovenous fistulae in haemodialysis patients, discusses its roles in these settings, and presents a review of commonly encountered complications.

Pulmonary arterio-venous micro fistulae - Diagnostic

International Nuclear Information System (INIS)

Ebram, J.C.

1989-01-01

Four patients with pulmonary arterio-venous micro-fistulae - of which two were male (50%) - the ages varying from 10 to 43 (X sup(∼) = 22,7), were studied at the Cardiology Centre of the 6th Ward of Santa Casa da Misericordia Hospital in Rio de Janeiro. They were all basically suffering from Manson's Schistosomiasis, the hepato-splenic form in 3 cases (75%) and the Rendu Osler Weber disease with juvenile cirrhosis in 1 case (25%). All four of them had portal hypertension. The individual cases were clinically evaluate with X-rays, scintillographic and hemodynamic tests. (author)

Pediatric congenital vertebral artery arteriovenous malformation

International Nuclear Information System (INIS)

Shownkeen, Harish; Chenelle, Andrew G.; Origitano, Thomas C.; Bova, Davide

2003-01-01

Vertebral arteriovenous fistulas are rare in children and the congenital form has been seldom reported in the literature. Prior to using endovascular therapy techniques, only surgery was the main treatment. The most common endovascular treatment is through the use of detachable balloons. This report describes the clinical and radiological findings of a congenital vertebral artery fistula in a 20-month-old child. Balloons could not be safely employed; therefore, embolization was performed with Guglielmi detachable microcoils. We review the history and treatment of these lesions, their clinical presentation, and imaging features, including their outcome, with particular attention to the pediatric population. (orig.)

Creation of an iliac arteriovenous shunt lowers blood pressure in chronic obstructive pulmonary disease patients with hypertension.

LENUS (Irish Health Repository)

Faul, John

2014-01-28

Vasodilators are used with caution in patients with chronic obstructive pulmonary disease (COPD). We have developed a device for percutaneous arteriovenous shunt creation in the iliac region to increase cardiac output and oxygen delivery for patients with COPD. Although this device does not cause significant blood pressure changes in normotensive patients with COPD, we hypothesized that arteriovenous shunt creation might cause vasodilator effects in hypertensive patients because of a reduction in vascular resistance.

Steam drum level control studies of a natural circulation multi loop reactor

Energy Technology Data Exchange (ETDEWEB)

Kumar, Rajesh; Contractor, A.D.; Srivastava, Abhishek; Lele, H.G. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Reactor Safety Div.; Vaze, K.K. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Reactor Design and Development Group

2013-12-15

The proposed heavy water moderated and light water cooled pressure tube type boiling water reactor works on natural circulation at all power levels. It has parallel inter-connected loops with 452 boiling channels in the main heat transport system configuration. These multiple (four) interconnected loops influence the steam drum level control adversely through the common reactor inlet header. Alternate design studies made earlier for efficient control of SD levels have shown favorable results. This has lead to explore further the present scheme with the compartmentalization of CRIH into four compartments catering to four loops separately. The conventional 3-element level control has been found to be working satisfactorily. The interconnections between ECCS header and inlet header compartments have also increased the safety margin for various LOCA and design basis events. The paper deals with the SD level control aspects for this novel MHT configuration which has been analyzed for various PIEs (Postulated Initiating Events) and found to be satisfactory. (orig.)

Congenital pelvic arteriovenous malformation: uncommon symptoms of lower limb venous hypertension.

Science.gov (United States)

Akimaro Kudo, F; Nishibe, T; Miyazaki, K; Flores, J; Yasuda, K

2001-12-01

Congenital pelvic arteriovenous malformations (AVMs) are rare and their clinical behavior is quite variable. A case of congenital pelvic AVM manifesting with unusual extrapelvic symptoms of ipsilateral leg pain is described. The causes of symptoms associated with congenital pelvic AVMs are discussed.

Complications following linear accelerator based stereotactic radiation for cerebral arteriovenous malformations

DEFF Research Database (Denmark)

Skjøth-Rasmussen, Jane; Roed, Henrik; Ohlhues, Lars

2010-01-01

Primarily, gamma knife centers are predominant in publishing results on arteriovenous malformations (AVM) treatments including reports on risk profile. However, many patients are treated using a linear accelerator-most of these at smaller centers. Because this setting is different from a large...

Magnetic resonance angiography of arteriovenous malformation in the brainstem

Energy Technology Data Exchange (ETDEWEB)

Oyama, Hirofumi; Kida, Yoshihisa; Kobayashi, Tatsuya; Tanaka, Takayuki; Iwakoshi, Takayasu; Kai, Osamu; Hirose, Mitsuhiko [Komaki City Hospital, Aichi (Japan)

1993-11-01

The magnetic resonance (MR) angiography appearance of arteriovenous malformation (AVM) in the tegmentum and pons is described. The interpeduncular perforating branches of the posterior cerebral artery and median pontine branches of the basilar artery were seen more clearly by MR angiography than by conventional angiography. MR angiography was very useful for the follow-up of AVM after stereotactic radiosurgery. (author).

Graft intolerance syndrome requiring graft nephrectomy after late kidney graft failure: can it be predicted? A retrospective cohort study.

Science.gov (United States)

Bunthof, Kim L W; Verhoeks, Carmen M; van den Brand, Jan A J G; Hilbrands, Luuk B

2018-02-01

Graft nephrectomy is recommended in case of early graft failure. When the graft fails more than 3-6 months after transplantation, it is current practice to follow a wait-and-see policy. A common indication for graft removal is the graft intolerance syndrome. We aimed to create a risk prediction model for the occurrence of graft intolerance resulting in graft nephrectomy. We collected data of kidney transplantations performed in our center between 1980 and 2010 that failed at least 6 months after transplantation. We evaluated the association between baseline characteristics and the occurrence of graft nephrectomy because of graft intolerance using a competing risk regression model. Prognostic factors were included in a multivariate prediction model. In- and exclusion criteria were met in 288 cases. In 48 patients, the graft was removed because of graft intolerance. Donor age, the number of rejections, and shorter graft survival were predictive factors for graft nephrectomy because of the graft intolerance syndrome. These factors were included in a prediction rule. Using donor age, graft survival, and the number of rejections, clinicians can predict the need for graft nephrectomy with a reasonable accuracy. © 2017 Steunstichting ESOT.

Mechanical evaluation of space closure loops in orthodontics.

Science.gov (United States)

Rodrigues, Eduardo Uggeri; Maruo, Hiroshi; Guariza Filho, Odilon; Tanaka, Orlando; Camargo, Elisa Souza

2011-01-01

This study evaluated the mechanical performance of teardrop-shaped loops and teardrop-shaped loops with helix used in orthodontic space closure. Sixty retraction loops made with 0.019" x 0.025" stainless steel (SS) and beta-titanium (BT) wires were used. They were attached to a testing machine to measure the magnitudes of the sagittal force and the load-deflection ratio necessary for 1 mm, 2 mm and 3 mm activation. The results demonstrated that the BT alloy presented significantly smaller mean values (p < 0.01) of sagittal force and load-deflection than the SS alloy. The loop with the highest mean value of sagittal force and load-deflection was the teardrop-shaped loop (p < 0.01). Differences were observed in the mean values of sagittal force and load-deflection among activations, and the highest mean value was found in the activation of 3 mm, while the smallest mean value was evident in the activation of 1 mm (p < 0.01). It could be concluded that the metallic alloy used and the presence of a helix in configuration of the loops may have a strong influence on the sagittal force produced and on the load-deflection ratio; the teardrop-shaped loops and teardrop-shaped loops with helix in BT presented the release of lighter forces; the teardrop-shaped loop in SS generated a high load-deflection ratio, providing high magnitudes of horizontal force during its deactivation.

Mechanical evaluation of space closure loops in Orthodontics

Directory of Open Access Journals (Sweden)

Eduardo Uggeri Rodrigues

2011-02-01

Full Text Available This study evaluated the mechanical performance of teardrop-shaped loops and teardrop-shaped loops with helix used in orthodontic space closure. Sixty retraction loops made with 0.019" x 0.025" stainless steel (SS and beta-titanium (BT wires were used. They were attached to a testing machine to measure the magnitudes of the sagittal force and the load-deflection ratio necessary for 1 mm, 2 mm and 3 mm activation. The results demonstrated that the BT alloy presented significantly smaller mean values (p < 0.01 of sagittal force and load-deflection than the SS alloy. The loop with the highest mean value of sagittal force and load-deflection was the teardrop-shaped loop (p < 0.01. Differences were observed in the mean values of sagittal force and load-deflection among activations, and the highest mean value was found in the activation of 3 mm, while the smallest mean value was evident in the activation of 1 mm (p < 0.01. It could be concluded that the metallic alloy used and the presence of a helix in configuration of the loops may have a strong influence on the sagittal force produced and on the load-deflection ratio; the teardrop-shaped loops and teardrop-shaped loops with helix in BT presented the release of lighter forces; the teardrop-shaped loop in SS generated a high load-deflection ratio, providing high magnitudes of horizontal force during its deactivation.

Double Coaxial Microcatheter Technique for Glue Embolization of Renal Arteriovenous Malformations

International Nuclear Information System (INIS)

Uchikawa, Yoko; Mori, Kensaku; Shiigai, Masanari; Konishi, Takahiro; Hoshiai, Sodai; Ishigro, Toshitaka; Hiyama, Takashi; Nakai, Yasunobu; Minami, Manabu

2015-01-01

PurposeTo demonstrate the technical benefit of the double coaxial microcatheter technique for embolization of renal arteriovenous malformations (AVMs) with n-butyl cyanoacrylate and iodized oil (glue).Materials and MethodsSix consecutive patients (1 man and 5 women; mean age 61 years; range 44–77 years) with renal AVMs were included. Five patients had hematuria, and one had a risk of heart failure due to a large intrarenal arteriovenous shunt. All patients underwent transarterial embolization using glue and the double coaxial microcatheter technique with outer 2.6F and inner 1.9F microcatheters. After glue injection, the inner microcatheter was retracted, while the outer microcatheter was retained. We assessed the complications and clinical outcomes of this technique.ResultsTechnical success was achieved in all patients. In 9 sessions, 34 feeding arteries were embolized with glue using the double coaxial microcatheter technique, 1 was embolized with glue using a single microcatheter, and 2 were embolized with coils. The double coaxial microcatheter technique was useful for selecting small tortuous feeding arteries, preventing glue reflux to the proximal arteries, and approaching multiple feeding arteries without complete retraction of the microcatheters. As a minor complication, glue migrated into the venous system in four patients without any sequelae. In all patients, favorable clinical outcomes, including hematuria cessation in five patients and improvement of the large intrarenal arteriovenous shunt in one patient, were obtained without deterioration of renal function.ConclusionGlue embolization with the double coaxial microcatheter technique was useful for treating renal AVMs with multiple tortuous feeding arteries

Double Coaxial Microcatheter Technique for Glue Embolization of Renal Arteriovenous Malformations

Energy Technology Data Exchange (ETDEWEB)

Uchikawa, Yoko, E-mail: jauchikawa@gmail.com [University of Tsukuba Hospital, Department of Radiology (Japan); Mori, Kensaku, E-mail: moriken@md.tsukuba.ac.jp [University of Tsukuba, Department of Radiology, Faculty of Medicine (Japan); Shiigai, Masanari, E-mail: m-41gai@yahoo.co.jp [Tsukuba Medical Center Hospital, Department of Radiology (Japan); Konishi, Takahiro, E-mail: soratobukangaruu@gmail.com [University of Tsukuba Hospital, Department of Radiology (Japan); Hoshiai, Sodai, E-mail: hoshiai@sb4.so-net.ne.jp [Ibaraki Prefectural Central Hospital, Department of Radiology (Japan); Ishigro, Toshitaka, E-mail: suzutokei@gmail.com; Hiyama, Takashi, E-mail: med-tak@hotmail.com [University of Tsukuba Hospital, Department of Radiology (Japan); Nakai, Yasunobu, E-mail: nakaiya@tmch.or.jp [Tsukuba Medical Center Hospital, Department of Neurosurgery (Japan); Minami, Manabu, E-mail: mminami@md.tsukuba.ac.jp [University of Tsukuba, Department of Radiology, Faculty of Medicine (Japan)

2015-10-15

PurposeTo demonstrate the technical benefit of the double coaxial microcatheter technique for embolization of renal arteriovenous malformations (AVMs) with n-butyl cyanoacrylate and iodized oil (glue).Materials and MethodsSix consecutive patients (1 man and 5 women; mean age 61 years; range 44–77 years) with renal AVMs were included. Five patients had hematuria, and one had a risk of heart failure due to a large intrarenal arteriovenous shunt. All patients underwent transarterial embolization using glue and the double coaxial microcatheter technique with outer 2.6F and inner 1.9F microcatheters. After glue injection, the inner microcatheter was retracted, while the outer microcatheter was retained. We assessed the complications and clinical outcomes of this technique.ResultsTechnical success was achieved in all patients. In 9 sessions, 34 feeding arteries were embolized with glue using the double coaxial microcatheter technique, 1 was embolized with glue using a single microcatheter, and 2 were embolized with coils. The double coaxial microcatheter technique was useful for selecting small tortuous feeding arteries, preventing glue reflux to the proximal arteries, and approaching multiple feeding arteries without complete retraction of the microcatheters. As a minor complication, glue migrated into the venous system in four patients without any sequelae. In all patients, favorable clinical outcomes, including hematuria cessation in five patients and improvement of the large intrarenal arteriovenous shunt in one patient, were obtained without deterioration of renal function.ConclusionGlue embolization with the double coaxial microcatheter technique was useful for treating renal AVMs with multiple tortuous feeding arteries.

Aortic Graft Infection Secondary to Iatrogenic Transcolonic Graft Malposition.

Science.gov (United States)

Blank, Jacqueline J; Rothstein, Abby E; Lee, Cheong Jun; Malinowski, Michael J; Lewis, Brian D; Ridolfi, Timothy J; Otterson, Mary F

2018-01-01

Aortic graft infections are a rare but devastating complication of aortic revascularization. Often infections occur due to contamination at the time of surgery. Iatrogenic misplacement of the limbs of an aortobifemoral graft is exceedingly rare, and principles of evaluation and treatment are not well defined. We report 2 cases of aortobifemoral bypass graft malposition through the colon. Case 1 is a 54-year-old male who underwent aortobifemoral bypass grafting for acute limb ischemia. He had previously undergone a partial sigmoid colectomy for diverticulitis. Approximately 6 months after vascular surgery, he presented with an occult graft infection. Preoperative imaging and intraoperative findings were consistent with graft placement through the sigmoid colon. Case 2 is a 60-year-old male who underwent aortobifemoral bypass grafting due to a nonhealing wound after toe amputation. His postoperative course was complicated by pneumonia, bacteremia thought to be secondary to the pneumonia, general malaise, and persistent fevers. Approximately 10 weeks after the vascular surgery, he presented with imaging and intraoperative findings of graft malposition through the cecum. Aortic graft infection is usually caused by surgical contamination and presents as an indolent infection. Case 1 presented as such; Case 2 presented more acutely. Both grafts were iatrogenically misplaced through the colon at the index operation. The patients underwent extra-anatomic bypass and graft explantation and subsequently recovered.

Colour Doppler ultrasound assessment of well-functioning mature arteriovenous fistulas for haemodialysis access

International Nuclear Information System (INIS)

Pietura, Radoslaw; Janczarek, Marzena; Zaluska, Wojciech; Szymanska, Anna; Janicka, Lucyna; Skublewska-Bednarek, Anna; Szczerbo-Trojanowska, Malgorzata

2005-01-01

Background: A well-functioning mature arteriovenous fistula is essential for the maintenance of haemodialysis in patients with chronic renal failure. The Brescia-Cimino arteriovenous fistula has the best survival characteristics and low rate of complications. The most common reason of fistula failure is thrombosis caused by stenosis. Colour Doppler ultrasonography has proven to be effective in the assessment of anatomical vascular features. The majority of studies were done in patients with clinically presumed arteriovenous fistula complications. However, only limited data are available about the well-functioning mature arteriovenous fistulas. The purpose of the present study was to evaluate completely asymptomatic, mature arteriovenous fistulas with colour Doppler ultrasound. Materials and methods: From July 2001 to April 2003, we examined 139 patients with the end-stage renal disease. They were in the range of 19-79 years of age (mean, 46.7 years). The study included only the patients who met the following criteria: (1) no difficulties with haemodialysis (as reported by nurses); (2) normal venous diastolic blood pressure (<150 mmHg) at monthly evaluation; (3) normal urea clearance x time/urea volume of distribution; (4) blood cells count, plasma electrolytes, and liver function at monthly evaluation. The mean fistula age was 26 months (S.D. = 21.9). The mean time of dialysis therapy was 49 months. Thirty-eight percent patients had primary fistulas, 23%-secondary, 11%-third and 11%-fourth, 4%-fifth, 5%-sixth, and 8% patients had more than sixth. Results: There was no correlation between: (1) patient's age and fistula age; (2) patient's age and number of fistulas in one patient; (3) fistula age and number of fistulas in one patient; (4) localization of fistula and fistula age. There was a strong correlation between dialysis therapy period and number of fistulas in one patient. The mean flow volume was 1204.1 ml/min (S.D. = 554). It was significantly higher in the

A Case of De Novo Anterior Condylar Dural Arteriovenous Fistula Long after Curative Transvenous Embolization of Contralateral Anterior Condylar Arteriovenous Fistula

Directory of Open Access Journals (Sweden)

Shinya Hagiwara

2016-01-01

Full Text Available We report on a 55-year-old man who developed a de novo DAVF in left ACC 5 years after curative transvenous embolization for DAVF in right ACC. Angiography revealed that the de novo lesion demonstrated more aggressive arteriovenous shunt flow than the initial lesion. Successful transvenous embolization was performed for also the second lesion. The authors describe the possible pathophysiological mechanisms and management strategies for this rare occurrence.

Arterio-venous flow between monochorionic twins determined during intra-uterine transfusion. Nonlinear decay of adult red blood cells

Energy Technology Data Exchange (ETDEWEB)

Gemert, Martin J C van; Wijngaard, Jeroen P H M van den [Laser Centre and Department of Obstetrics, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands); Pasman, Suzanne A; Vandenbussche, Frank P H A [Division of Fetal Medicine, Department of Obstetrics, Leiden University Medical Centre, Leiden (Netherlands); Lopriore, Enrico [Division of Neonatology, Department of Pediatrics, Leiden University Medical Centre, Leiden (Netherlands)], E-mail: m.j.vangemert@amc.uva.nl

2008-07-07

Recently, we derived equations relating the flow of adult red blood cells through a placental arterio-venous anastomosis with intra-uterine and post-natal measured adult hemoglobin concentrations. In this letter, we re-derived the equations, now including a more realistic nonlinear decay of adult red blood cells, and re-evaluated the measurement accuracy of the arterio-venous flow and the lifetime of the red blood cells. (letter to the editor)

Primary loop simulation of the SP-100 space nuclear reactor

International Nuclear Information System (INIS)

Borges, Eduardo M.; Braz Filho, Francisco A.; Guimaraes, Lamartine N.F.

2011-01-01

Between 1983 and 1992 the SP-100 space nuclear reactor development project for electric power generation in a range of 100 to 1000 kWh was conducted in the USA. Several configurations were studied to satisfy different mission objectives and power systems. In this reactor the heat is generated in a compact core and refrigerated by liquid lithium, the primary loops flow are controlled by thermoelectric electromagnetic pumps (EMTE), and thermoelectric converters produce direct current energy. To define the system operation point for an operating nominal power, it is necessary the simulation of the thermal-hydraulic components of the space nuclear reactor. In this paper the BEMTE-3 computer code is used to EMTE pump design performance evaluation to a thermalhydraulic primary loop configuration, and comparison of the system operation points of SP-100 reactor to two thermal powers, with satisfactory results. (author)

Dynamic behavior of the intensified alternative configurations for quaternary distillation

DEFF Research Database (Denmark)

Ramirez-Marquez, Cesar; Cabrera-Ruiz, Julián; Juan Gabriel Segovia-Hernandez, Juan Gabriel

2016-01-01

Process intensification emerges as an important tool in the synthesis of multicomponent distillation configurations aimed at the reduction of the energy use and capital costs. Operational and fixed costs savings coupled with simplicity and controllability design configurations appear as an essent......Process intensification emerges as an important tool in the synthesis of multicomponent distillation configurations aimed at the reduction of the energy use and capital costs. Operational and fixed costs savings coupled with simplicity and controllability design configurations appear...... value decomposition technique in all frequency domain. In order to complete the control study, the distillation schemes were subjected to closed-loop dynamic simulations. The results show that there are cases in which the intensified sequences do not only provide energy savings, but also may offer...

Effect of Embolization Material in the Calculation of Dose Deposition in Arteriovenous Malformations

International Nuclear Information System (INIS)

De la Cruz, O. O. Galvan; Moreno-Jimenez, S.; Larraga-Gutierrez, J. M.; Celis-Lopez, M. A.

2010-01-01

In this work it is studied the impact of the incorporation of high Z materials (embolization material) in the dose calculation for stereotactic radiosurgery treatment for arteriovenous malformations. A statistical analysis is done to establish the variables that may impact in the dose calculation. To perform the comparison pencil beam (PB) and Monte Carlo (MC) calculation algorithms were used. The comparison between both dose calculations shows that PB overestimates the dose deposited. The statistical analysis, for the quantity of patients of the study (20), shows that the variable that may impact in the dose calculation is the volume of the high Z material in the arteriovenous malformation. Further studies have to be done to establish the clinical impact with the radiosurgery result.

A Configuration Model of Organizational Culture

Directory of Open Access Journals (Sweden)

Daniel Dauber

2012-01-01

Full Text Available The article proposes a configuration model of organizational culture, which explores dynamic relationships between organizational culture, strategy, structure, and operations of an organization (internal environment and maps interactions with the external environment (task and legitimization environment. A major feature of the configuration model constitutes its well-defined processes, which connect the elements of the model systematically to each other, such as single- and double-loop learning, operationalization of strategies, legitimization management, and so on. The model is grounded in a large review of literature in different research areas and builds on widely recognized models in the field of organization and culture theory. It constitutes a response to the call for new models, which are able to explain and facilitate the exploration of the empirical complexity that organizations face today. The configuration model of organizational culture is of particular interest to scholars who investigate into cultural phenomena and change over time.

Grafting

Energy Technology Data Exchange (ETDEWEB)

Garnett, J L [New South Wales Univ., Kensington (Australia). School of Chemistry

1979-01-01

The unique value of ionizing radiation for the initiation of grafting to backbone polymers is discussed. The principles of the technique are briefly reviewed. The conditions under which free radicals and ions participate in these reactions are examined. Examples of representative grafting processes are considered to illustrate where the technique can be of potential commercial value to a wide range of industries. The general principles of these grafting reactions are shown to be applicable to radiation induced rapid cure technology such as is provided by electron beam processing facilities. Grafting reactions initiated by UV are also treated and shown to be of importance because of the many similarities in properties of the ionizing radiation and UV systems, also the rapid industrial exploitation of EB and sensitized UV processing technology. Possible future trends in radiation grafting are outlined.

Challenges in the management of massive intraorbital and hemifacial arteriovenous malformation as causing life-threatening epistaxis

Directory of Open Access Journals (Sweden)

Anura Michelle Manuel

2017-03-01

Full Text Available Arteriovenous malformations are congenital lesions that may evolve with time and manifest in a plethora of presentations. They can occur as torrential epistaxis when it extensively involves the facial region. Multi-imaging modalities are available to assist in characterizing the structure of the lesion as well as its location and extent. This complex disease requires a multidisciplinary team approach with preoperative embolization and surgery. We present a rare cause of life-threatening epistaxis in a gentleman with a longstanding orbital and hemifacial arteriovenous malformation and discuss the complexities involved in its management.

A case of pancreatic arteriovenous malformation with portal hypertension: treatment with transjuguIar intrahepatic portosystemic shunt

Energy Technology Data Exchange (ETDEWEB)

Kim, Seong Hoon; Kim, Young Whan; Kim, Yong Joo [School of Medicine, Kyungpook National Univ., Daegu (Korea, Republic of)

2004-03-01

Arteriovenous malformation of the pancreas is a rare disease, and it is manifested by gastrointestinal bleeding and/or portal hypertension. Surgery is definitely the treatment of choice at the early stage of the disease, and a transcatheter embolization is an alternative treatment for the control of bleeding and if the lesion is surgically inaccessible. We describe a 62-year-old man who had refractory ascites and esophageal variceal bleeding caused by a pancreatic arteriovenous malformation associated with portal hypertension; this was successfully treated by a transjugular intrahepatic portosystemic shunt.

A case of pancreatic arteriovenous malformation with portal hypertension: treatment with transjuguIar intrahepatic portosystemic shunt

International Nuclear Information System (INIS)

Kim, Seong Hoon; Kim, Young Whan; Kim, Yong Joo

2004-01-01

Arteriovenous malformation of the pancreas is a rare disease, and it is manifested by gastrointestinal bleeding and/or portal hypertension. Surgery is definitely the treatment of choice at the early stage of the disease, and a transcatheter embolization is an alternative treatment for the control of bleeding and if the lesion is surgically inaccessible. We describe a 62-year-old man who had refractory ascites and esophageal variceal bleeding caused by a pancreatic arteriovenous malformation associated with portal hypertension; this was successfully treated by a transjugular intrahepatic portosystemic shunt

Investigation of Inner Loop Flight Control Strategies for High-Speed Research

Science.gov (United States)

Newman, Brett; Kassem, Ayman

1999-01-01

This report describes the activities and findings conducted under contract NAS1-19858 with NASA Langley Research Center. Subject matter is the investigation of suitable flight control design methodologies and solutions for large, flexible high-speed vehicles. Specifically, methodologies are to address the inner control loops used for stabilization and augmentation of a highly coupled airframe system possibly involving rigid-body motion, structural vibrations, unsteady aerodynamics, and actuator dynamics. Techniques considered in this body of work are primarily conventional-based, and the vehicle of interest is the High-Speed Civil Transport (HSCT). Major findings include 1) current aeroelastic vehicle modeling procedures require further emphasis and refinement, 2) traditional and nontraditional inner loop flight control strategies employing a single feedback loop do not appear sufficient for highly flexible HSCT class vehicles, 3) inner loop flight control systems will, in all likelihood, require multiple interacting feedback loops, and 4) Ref. H HSCT configuration presents major challenges to designing acceptable closed-loop flight dynamics.

Three-Dimensional Printing of Vitrification Loop Prototypes for Aquatic Species.

Science.gov (United States)

Tiersch, Nolan J; Childress, William M; Tiersch, Terrence R

2018-05-16

Vitrification is a method of cryopreservation that freezes samples rapidly, while forming an amorphous solid ("glass"), typically in small (μL) volumes. The goal of this project was to create, by three-dimensional (3D) printing, open vitrification devices based on an elliptical loop that could be efficiently used and stored. Vitrification efforts can benefit from the application of 3D printing, and to begin integration of this technology, we addressed four main variables: thermoplastic filament type, loop length, loop height, and method of loading. Our objectives were to: (1) design vitrification loops with varied dimensions; (2) print prototype loops for testing; (3) evaluate loading methods for the devices; and (4) classify vitrification responses to multiple device configurations. The various configurations were designed digitally using 3D CAD (Computer Aided Design) software, and prototype devices were produced with MakerBot ® 3D printers. The thermoplastic filaments used to produce devices were acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA). Vitrification devices were characterized by the film volumes formed with different methods of loading (pipetting or submersion). Frozen films were classified to determine vitrification quality: zero (opaque, or abundant crystalline ice formation); one (translucent, or partial vitrification), or two (transparent, or substantial vitrification, glass). A published vitrification solution was used to conduct experiments. Loading by pipetting formed frozen films more reliably than by submersion, but submersion yielded fewer filling problems and was more rapid. The loop designs that yielded the highest levels of vitrification enabled rapid transfer of heat, and most often were characterized as being longer and consisting of fewer layers (height). 3D printing can assist standardization of vitrification methods and research, yet can also provide the ability to quickly design and fabricate custom devices when

A rare case of spinal dural arteriovenous fistula

Directory of Open Access Journals (Sweden)

Mariya Apostolova

2012-12-01

Full Text Available Spinal dural arteriovenous fistula (SDAVF is a rare vascular malformation of the spine. Only a limited number of cases of SDAVF have been reported in the current literature. We describe the case of a 74 year old male who presented with gradually progressive bilateral lower extremity weakness and bladder dysfunction and was subsequently diagnosed with SDAVF affecting both the thoracic and lumbar spine. The patient later underwent embolization with some improvement in his neurologic symptoms.

The adsorber loop concept for the contact between seawater and adsorber granulate

International Nuclear Information System (INIS)

Koske, P.H.; Ohlrogge, K.

1984-01-01

The present paper deals with the so-called ''adsorber loop concept'' in which the adsorber granulate is carried along with the seawater to be processed in a loop-like configuration and is separated again from the depleted water before this is leaving the adsorption unit. This concept enables high seawater velocities thus reducing the required bed area. Theoretical considerations are presented together with experimental results from field tests. (orig.) [de

Monitoring arterio-venous differences of glucose and lactate in the anesthetized rat with or without brain damage with ultrafiltration and biosensor technology

NARCIS (Netherlands)

Leegsma-Vogt, G; Venema, K; Postema, F; Korf, J

2001-01-01

Continuous monitoring of arterio-venous glucose and lactate differences may serve as a diagnostic tool to assess normal brain function and brain pathology. We describe a method and some results obtained with arterio-venous measurements of glucose and lactate in the blood of the

Grafted natural polymer as new drag reducing agent: An experimental approach

Directory of Open Access Journals (Sweden)

Abdulbari Hayder A.

2012-01-01

Full Text Available The present investigation introduces a new natural drag reducing agent which has the ability to improve the flow in pipelines carrying aqueous or hydrocarbon liquids in turbulent flow. Okra (Abelmoschus esculentus mucilage drag reduction performance was tested in water and hydrocarbon (gas-oil media after grafting. The drag reduction test was conducted in a buildup closed loop liquid circulation system consists of two pipes 0.0127 and 0.0381 m Inside Diameter (ID, four testing sections in each pipe (0.5 to 2.0 m, tank, pump and pressure transmitters. Reynolds number (Re, additive concentration and the transported media type (water and gas-oil, were the major drag reduction variables investigated. The experimental results show that, new additive drag reduction ability is high with maximum percentage of drag reduction (%Dr up to 60% was achieved. The experimental results showed that the drag reduction ability increased by increasing the additive concentration. The %Dr was found to increase by increasing the Re by using the water-soluble additive while it was found to decrease by increasing the Re when using the oil-soluble additive. The %Dr was higher in the 0.0381 m ID pipe. Finally, the grafted and natural mucilage showed high resistance to shear forces when circulated continuously for 200 seconds in the closed-loop system.

Conformal anomaly of generalized form factors and finite loop integrals

CERN Document Server

Chicherin, Dmitry

2017-01-01

We reveal a new mechanism of conformal symmetry breaking at Born level. It occurs in generalized form factors with several local operators and an on-shell state of massless particles. The effect is due to hidden singularities on collinear configurations of the momenta. This conformal anomaly is different from the holomorphic anomaly of amplitudes. We present a number of examples in four and six dimensions. We find an application of the new conformal anomaly to finite loop momentum integrals with one or more massless legs. The collinear region around a massless leg creates a contact anomaly, made visible by the loop integration. The anomalous conformal Ward identity for an $\\ell-$loop integral is a 2nd-order differential equation whose right-hand side is an $(\\ell-1)-$loop integral. We show several examples, in particular the four-dimensional scalar double box.

Transarterial embolisation of renal arteriovenous malformation: safety and efficacy in 24 patients with follow-up

International Nuclear Information System (INIS)

Eom, H.-J.; Shin, J.H.; Cho, Y.J.; Nam, D.H.; Ko, G.-Y.; Yoon, H.-K.

2015-01-01

Aim: To evaluate the efficacy and safety of renal artery embolisation (RAE) for renal arteriovenous malformation (AVM) as well as its outcomes. Materials and methods: The technical and clinical success rates, radiological and laboratory findings, and complications of RAE for 31 renal AVMs in 24 patients (M:F=9:15, mean age 46 years) at two separate medical institutions were retrospectively evaluated. Technical success was defined as complete occlusion of feeding arteries with no residual nidus seen on post-treatment angiography. Clinical failure was defined as recurrence of haematuria, presence of AVM on follow-up ultrasound or computed tomography, repeated RAE or surgery for the control of haematuria. Overall clinical success was defined as resolution haematuria or disappearance of AVM on follow-up imaging after single or multiple sessions of RAE. Results: Types of renal AVM were AVM, arterio-venous fistula (AVF) with intranidal aneurysm, and acquired AVF in 19, 1, and 4 patients, respectively. 18 patients (75%) underwent a single session of RAE, while 6 patients (25%) had two or more sessions of RAE. The level of embolisation was feeder, segmental artery, and main renal artery in 28 (90%), 2 (6%), and 1 (4%) procedures, respectively. Coil, n-butyl 2-cyanoacrylate, and polyvinyl alcohol were the most frequently chosen embolic materials and were used in 19, 14, and 8 procedures, respectively. The clinical success rate after initial RAE was 67% (16/24). Overall clinical success rate, including multisession RAE, was 88% (21/24). The technical success rate of 31 procedures was 65% (20/31). Among 11 technical failures in 10 patients, 4 achieved clinical success without additional RAE, 3 underwent second session RAE to achieve clinical success, and 3 patients underwent nephrectomy due to recurrence. Conclusion: RAE is a safe and effective treatment for renal AVM. Technical failure of RAE does not always lead to clinical failure and multiple embolisation sessions may be

ORNL compact loop antenna design for TFTR and Tore Supra

International Nuclear Information System (INIS)

Taylor, D.J.; Baity, F.W.; Bryan, W.E.; Hoffman, D.J.; McIlwain, R.L.; Ray, J.M.

1987-01-01

The goal supplemental ion cyclotron resonance heating (ICRH) of fusion plasma is to deliver power at high efficiencies deep within the plasma. The technology for fast-wave ICRH has reached the point of requiring ''proof-of-performance'' demonstration of specific antenna configurations of specific antenna configurations and their mechanical adequacy for operating in a fusion environment. Oak Ridge National Laboratory (ORNL) has developed the compact loop antenna concept based on a resonant double loop (RDL) configuration for use in both Tokamak Fusion Test Reactor (TFTR) and the Tore Supra ICRH programs. A description and a comparison of the technologies developed in the two designs are presented. The electrical circuit and the mechanical philosophy employed are the same for both antennas, but different operating environments result in substantial differences in the design of specific components. The ORNL TFTR antenna is designed to deliver 4 MW over a 2-s pulse, and the ORNL Tore Supra antenna is designed for 4 MW and essentially steady-state conditions. The TFTR design embodies the first operations compact RDL antenna, and the Tore Supra antenna extends the technology to an operational duty cycle consistent with reactor-relevant applications. 7 refs., 5 figs

Web-based ground loop supervision system for the TJ-II Stellarator

International Nuclear Information System (INIS)

Pena, A. de la; Lapayese, F.; Pacios, L.; Carrasco, R.

2005-01-01

To minimize electromagnetic interferences in diagnostic and control signals, and to guarantee safe operation of TJ-II, ground loops must be avoided. In order to meet this goal, the whole grounding system of the TJ-II was split into multiple single branches that are connected at a single earth point located near the TJ-II structure in the torus hall. A real-time ground loop supervision system (GLSS) has been designed, manufactured and tested by the TJ-II control group for detecting unintentional short circuits between isolated grounded parts. A web server running on the real-time operating system OS-9 provides remote access to the real-time ground loops measurement. Ground loops monitoring and different operation modes can be configured via any web browser. This paper gives the detailed design of the whole TJ-II ground loop supervision system and its results during its operation

Web-based ground loop supervision system for the TJ-II Stellarator

Energy Technology Data Exchange (ETDEWEB)

Pena, A. de la [Asociacion EURATOM-CIEMAT Para Fusion, Avd. Complutense 22, 28040 Madrid (Spain)]. E-mail: a.delapena@ciemat.es; Lapayese, F. [Asociacion EURATOM-CIEMAT Para Fusion, Avd. Complutense 22, 28040 Madrid (Spain); Pacios, L. [Asociacion EURATOM-CIEMAT Para Fusion, Avd. Complutense 22, 28040 Madrid (Spain); Carrasco, R. [Asociacion EURATOM-CIEMAT Para Fusion, Avd. Complutense 22, 28040 Madrid (Spain)

2005-11-15

To minimize electromagnetic interferences in diagnostic and control signals, and to guarantee safe operation of TJ-II, ground loops must be avoided. In order to meet this goal, the whole grounding system of the TJ-II was split into multiple single branches that are connected at a single earth point located near the TJ-II structure in the torus hall. A real-time ground loop supervision system (GLSS) has been designed, manufactured and tested by the TJ-II control group for detecting unintentional short circuits between isolated grounded parts. A web server running on the real-time operating system OS-9 provides remote access to the real-time ground loops measurement. Ground loops monitoring and different operation modes can be configured via any web browser. This paper gives the detailed design of the whole TJ-II ground loop supervision system and its results during its operation.

OSCILLATION OF NEWLY FORMED LOOPS AFTER MAGNETIC RECONNECTION IN THE SOLAR CHROMOSPHERE

Energy Technology Data Exchange (ETDEWEB)

Yang, Shuhong [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Xiang, Yongyuan, E-mail: shuhongyang@nao.cas.cn [Fuxian Solar Observatory, Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China)

2016-03-10

With the high spatial and temporal resolution Hα images from the New Vacuum Solar Telescope, we focus on two groups of loops with an X-shaped configuration in the dynamic chromosphere. We find that the anti-directed loops approach each other and reconnect continually. The connectivity of the loops is changed and new loops are formed and stack together. The stacked loops are sharply bent, implying that they are greatly impacted by the magnetic tension force. When another reconnection process takes place, one new loop is formed and stacks with the previously formed ones. Meanwhile, the stacked loops retract suddenly and move toward the balance position, performing an overshoot movement, which led to an oscillation with an average period of about 45 s. The oscillation of newly formed loops after magnetic reconnection in the chromosphere is observed for the first time. We suggest that the stability of the stacked loops is destroyed due to the attachment of the last new loop and then suddenly retract under the effect of magnetic tension. Because of the retraction, another lower loop is pushed outward and performs an oscillation with a period of about 25 s. The different oscillation periods may be due to their difference in three parameters, i.e., loop length, plasma density, and magnetic field strength.

Embolization of brain arteriovenous malformations using tracker catheter

International Nuclear Information System (INIS)

Kim, Sun Yong; Son, Mi Young; Jang, Jae Chun; Hwang, Mi Soo; Park, Bok Hwan

1990-01-01

With the recent advance in micro catheters, steerable guide wires, balloons, embolic materials and digital subtraction angiography (DSA), as well as technical refinements in endovascular surgery, there has been a revolution in therapeutic strategies for cerebral arteriovenous malformations (AVMs). We have performed super selective angiography and embolization with Tracker micro catheter about 12 cases of brain AVMs for therapeutic and preoperative aims. This micro catheter and guide wire provided high selectivity of feeding artery, greater maneuverability and useful for deliver various embolus materials

Grafting and curing

International Nuclear Information System (INIS)

Garnett, J.L.; Loo-Teck Ng; Visay Viengkhou

1998-01-01

Progress in radiation grafting and curing is briefly reviewed. The two processes are shown to be mechanistically related. The parameters influencing yields are examined particularly for grafting. For ionising radiation grafting systems (EB and gamma ray) these include solvents, substrate and monomer structure, dose and dose-rate, temperature and more recently role of additives. In addition, for UV grafting, the significance of photoinitiators is discussed. Current applications of radiation grafting and curing are outlined. The recent development of photoinitiator free grafting and curing is examined as well as the potential for the new excimer laser sources. The future application of both grafting and curing is considered, especially the significance of the occurrence of concurrent grafting during cure and its relevance in environmental considerations

Experimental analysis of flowrates distribution features in double-loop reactor channels

International Nuclear Information System (INIS)

Avdeev, E.F.; Chusov, I.A.

2013-01-01

Experimental data on the flowrate distribution in working channels dummies of a research reactor model with double-loop configuration are presented in the paper. The procedures of experiments and received experimental data processing are provided in details [ru

Solar cooling in the hardware-in-the-loop test; Solare Kuehlung im Hardware-in-the-Loop-Test

Energy Technology Data Exchange (ETDEWEB)

Lohmann, Sandra; Radosavljevic, Rada; Goebel, Johannes; Gottschald, Jonas; Adam, Mario [Fachhochschule Duesseldorf (Germany). Erneuerbare Energien und Energieeffizienz E2

2012-07-01

The first part of the BMBF-funded research project 'Solar cooling in the hardware-in-the-loop test' (SoCool HIL) deals with the simulation of a solar refrigeration system using the simulation environment Matlab / Simulink with the toolboxes Stateflow and Carnot. Dynamic annual simulations and DoE supported parameter variations were used to select meaningful system configurations, control strategies and dimensioning of components. The second part of this project deals with hardware-in-the-loop tests using the 17.5 kW absorption chiller of the company Yazaki Europe Limited (Hertfordshire, United Kingdom). For this, the chiller is operated on a test bench in order to emulate the behavior of other system components (solar circuit with heat storage, recooling, buildings and cooling distribution / transfer). The chiller is controlled by a simulation of the system using MATLAB / Simulink / Carnot. Based on the knowledge on the real dynamic performance of the chiller the simulation model of the chiller can then be validated. Further tests are used to optimize the control of the chiller to the current cooling load. In addition, some changes in system configurations (for example cold backup) are tested with the real machine. The results of these tests and the findings on the dynamic performance of the chiller are presented.

Challenges in the management of massive intraorbital and hemifacial arteriovenous malformation as causing life-threatening epistaxis.

Science.gov (United States)

Manuel, Anura Michelle; Kalimuthu, Santhi; Pathmanathan, Sitra Siri; Narayanan, Prepageran; Zainal Abidin, Zurina; Azmi, Khairul; Khalil, Alizan

2017-04-01

Arteriovenous malformations are congenital lesions that may evolve with time and manifest in a plethora of presentations. They can occur as torrential epistaxis when it extensively involves the facial region. Multi-imaging modalities are available to assist in characterizing the structure of the lesion as well as its location and extent. This complex disease requires a multidisciplinary team approach with preoperative embolization and surgery. We present a rare cause of life-threatening epistaxis in a gentleman with a longstanding orbital and hemifacial arteriovenous malformation and discuss the complexities involved in its management. Copyright © 2017. Published by Elsevier Taiwan.

Uterine arteriovenous malformation as a rare cause of genital bleeding

International Nuclear Information System (INIS)

Rodriguez, A.; Escartin, I.; Riazuelo, G.; Zaragozano, R.

2002-01-01

Uterine arteriovenous malformation is a rarely described entity, the presenting sign of which is usually genital bleeding. We report a case of this malformation in a woman of child-bearing age with a history of traumatic delivery and repeated subsequent curettage, describing the ultrasound, computed tomography and magnetic resonance findings, as well as the results of arteriography. (Author) 5 refs

Glucose pump test can be used to measure blood flow rate of native arteriovenous fistula in chronic hemodialysis.

Science.gov (United States)

Yavuz, Y C; Selcuk, N Y; Altıntepe, L; Güney, I; Yavuz, S

2018-01-01

In chronic hemodialysis patients, the low flow of vascular access may leads to inadequate dialysis, increased rate of hospitalization, morbidity, and mortality. It was found that surveillance should be performed for native arteriovenous (AV) should not be performed for AV graft in various studies. However, surveillance was done in graft AV fistulas in most studies. Doppler ultrasonography (US) was suggested for surveillance of AV fistulas by the last vascular access guideline of National Kidney Foundation Disease Outcomes Quality Initiative (NKF KDOQI). The aim of study is to determine whether glucose pump test (GPT) is used for surveillance of native AV fistulas by using Doppler US as reference. In 93 chronic hemodialysis patients with native AV fistula, blood flow rates were measured by Doppler US and GPT. For GPT, glucose was infused to 16 mL/min by pump and was measured at basal before the infusion and 11 s after the start of the infusion by glucometer. Doppler US was done by an expert radiologist. Used statistical tests were Mann-Whitney U test, Friedman test, regression analysis, and multiple regression analysis. Median values of blood flow rates measured by GPT (707 mL/min) and by Doppler US (700 mL/min) were not different (Z = 0.414, P = 0.678). Results of GPT and Doppler US measurements were positive correlate by regression analysis. The mean GPT value of diabetic patients (n = 39; 908 mL/min) was similar to that of nondiabetic patients (n = 54; 751 mL/min; Z = 1.31, P = 0.188). GPT values measured at three different dialysis session did not differ from each other that by Friedman test (F = 0.92, P = 0.39). This showed that GPT was stable and reliable. Glucose pump test can be used to measure blood flow rate of native AV fistula. GPT is an accurate and reliable test.

Test results of reliable and very high capillary multi-evaporators / condenser loop

Energy Technology Data Exchange (ETDEWEB)

Van Oost, S; Dubois, M; Bekaert, G [Societe Anonyme Belge de Construction Aeronautique - SABCA (Belgium)

1997-12-31

The paper present the results of various SABCA activities in the field of two-phase heat transport system. These results have been based on a critical review and analysis of the existing two-phase loop and of the future loop needs in space applications. The research and the development of a high capillary wick (capillary pressure up to 38 000 Pa) are described. These activities have led towards the development of a reliable high performance capillary loop concept (HPCPL), which is discussed in details. Several loop configurations mono/multi-evaporators have been ground tested. The presented results of various tests clearly show the viability of this concept for future applications. Proposed flight demonstrations as well as potential applications conclude this paper. (authors) 7 refs.

Test results of reliable and very high capillary multi-evaporators / condenser loop

Energy Technology Data Exchange (ETDEWEB)

Van Oost, S.; Dubois, M.; Bekaert, G. [Societe Anonyme Belge de Construction Aeronautique - SABCA (Belgium)

1996-12-31

The paper present the results of various SABCA activities in the field of two-phase heat transport system. These results have been based on a critical review and analysis of the existing two-phase loop and of the future loop needs in space applications. The research and the development of a high capillary wick (capillary pressure up to 38 000 Pa) are described. These activities have led towards the development of a reliable high performance capillary loop concept (HPCPL), which is discussed in details. Several loop configurations mono/multi-evaporators have been ground tested. The presented results of various tests clearly show the viability of this concept for future applications. Proposed flight demonstrations as well as potential applications conclude this paper. (authors) 7 refs.

Extrasinusal dural arteriovenous malformations

International Nuclear Information System (INIS)

Piske, R.L.; Lasjaunias, P.

1988-01-01

Of 60 cases of dural arteriovenous malformations (DAVM) explored and treated in the Vascular Neuroradiology Unit of the Hospital of Bicetre between 1980 and 1986, 3 presented in an extrasinusal location: intraorbital, middle cerebral fossa and the region of the superior orbital fissure. We have not found any prior description of DAVMs in these regions in the literature. The classic concept that DAVMs rise in direct relationship with the dural sinuses is limited. We believe that these lesions may also developed in relationship with the venous drainage system of the sinuses and the venous drainage of the peripheral nervous system. We note that the superior ophthalmic vein which drains DAVMs of the orbit and the olfactory vein which drains DAVMs of the anterior cranial fossa and other veins that accompany the cranial nerves through the skull base have the characteristics of emissary veins. It may be that DAVMs can develop wherever veins follow a transosseous trajectory. (orig.)

Apneic oxygenation combined with extracorporeal arteriovenous carbon dioxide removal provides sufficient gas exchange in experimental lung injury

DEFF Research Database (Denmark)

Nielsen, Niels Dalsgaard; Kjærgaard, Benedict; Nielsen, Jakob Koefoed

In this porcine lung injury model, apneic oxygenation with arteriovenous CO2 removal provided sufficient gas exchange and stable hemodynamics, indicating that the method might have a potential in the treatment of severe ARDS.   Acknowledgements The membrane lungs were kindly provided by Novalung GmbH, Germany.......Background and aim of study We hypothesized that continuous high airway pressure without ventilatory movements (apneic oxygenation), using an open lung approach, combined with extracorporeal, pumpless, arterio-venous, carbon dioxide (CO2) removal would provide adequate gas exchange in acute lung...

Interventional treatment of pulmonary arteriovenous malformations

DEFF Research Database (Denmark)

Andersen, Poul Erik; Kjeldsen, Anette Drøhse

2010-01-01

Pulmonary arteriovenous malformations (PAVM) are congenital vascular communications in the lungs. They act as right to left shunts so that the blood running through these malformations is not oxygenated or filtered. These patients are typically hypoxaemic with exercise intolerance and are at high...... risk of paradoxical emboli to the brain and other organs. These malformations are most commonly seen in hereditary haemorrhagic telangiectasia (HHT) (Mb. Osler-Weber-Rendu syndrome). Nowadays, the generally accepted treatment strategy of first choice is embolization of the afferent arteries...... the functional level. Embolization is a well-established method of treating PAVM, with a significant effect on oxygenation of the blood. Screening for PAVM in patients at risk is recommended, especially in patients with HHT....

Retroperitoneal arteriovenous malformation extending through the inferior vena cava into the heart and causing inferior vena cava dissection

International Nuclear Information System (INIS)

Sung, Yon Mi; Choe, Yeon Hyeon; Park, Seung Woo; Park, Pyo Won; Sung, Chang Ohk

2005-01-01

We present a case of retroperitoneal arteriovenous malformation extending through the inferior vena cava into the heart, which was associated with dissection of the inferior vena cava in a 32-year-old female. Computed tomography and magnetic resonance imaging showed a double-lumen inferior vena cava and a rod-like solid component attached to a sac-like lesion in the right heart chambers. Digital subtraction angiography showed an arteriovenous malformation draining to the inner lumen of the inferior vena cava. (orig.)

A Highly Robust Single-Loop Current Control Scheme for Grid-Connected Inverter with an Improved LCCL Filter Configuration

DEFF Research Database (Denmark)

Pan, Donghua; Ruan, Xinbo; Wang, Xiongfei

2018-01-01

Single-loop current control is an attractive scheme for the LCL-type grid-connected inverter due to its simplicity and low cost. However, conventional single-loop control schemes, which command either the inverter current or the grid current, are subject to the specific resonance frequency regions....... The weighted average current control, which splits the filter capacitor into two parts (in form of an LCCL filter) and commands the current flowing between these two parts, is independent of the resonance frequency, but on the other hand, it is limited by the poor sensitivity to the grid impedance variation...... and weak stability in the grid current. These limitations are comprehensively explained in this paper and then addressed by identifying that the single-loop weighted average current control is equivalent to the dual-loop grid current control with an inherent capacitor current active damping. By tuning...

Pial Arteriovenous Fistula Caused by Trauma: A Case Report

OpenAIRE

NOMURA, Seiji; ISHIKAWA, Osamu; TANAKA, Kentaro; OTANI, Ryohei; MIURA, Keisuke; MAEDA, Keiichiro

2015-01-01

We report an extremely rare case of pial arteriovenous fistula (AVF) caused by trauma. A 61-year-old man suffered from brain contusion by a traffic accident. He was neurologically normal on admission. However, his headache gradually worsened, and partial seizures occurred thereafter. He presented with general tonic seizure 7 days after the head injury. Magnetic resonance imaging demonstrated the exacerbation of brain edema and an abnormal vein near the contusion. Subsequent angiography showed...

Grafting the alar rim: application as anatomical graft.

Science.gov (United States)

Gruber, Ronald P; Fox, Paige; Peled, Anne; Belek, Kyle A

2014-12-01

Alar rim contour and alar rim grafts have become essential components of rhinoplasty. Ideally, grafts of the nose should be anatomical in shape. So doing might make grafts of the alar rim more robust. The authors considered doing that by applying the graft as a continuous extension of the lateral crus. Twelve patients (two men and 10 women) constituted the study group (seven primary and five secondary cases). Of those, there were five concave rims, two concave rims with rim retraction, two boxy tips, and three cephalically oriented lateral crura. Surgical technique included the following: (1) an open approach was used; (2) a marginal incision that ignored the caudal margin of the lateral crus (the incision went straight posteriorly to a point 5 to 6 mm from the rim margin) was used; (3) a triangular graft was made to cover the exposed vestibular skin; (4) it was secured end to end to the caudal border of the lateral crus; and (5) the poster end was allowed to sit in a small subcutaneous pocket. Follow-up was 11 to 19 months. All 12 patients exhibited good rims as judged by a blinded panel. Rim retraction was not fully corrected in one patient, but no further treatment was required. One patient did require a secondary small rim graft for residual rim concavity. The concept of grafting the alar rim is strongly supported by the authors' results. The modifications the authors applied by designing the graft to be anatomical in shape has been a technical help.

Exchange bias and asymmetric hysteresis loops from a microscopic model of core/shell nanoparticles

International Nuclear Information System (INIS)

Iglesias, Oscar; Batlle, Xavier; Labarta, Amilcar

2007-01-01

We present Monte Carlo simulations of hysteresis loops of a model of a magnetic nanoparticle with a ferromagnetic core and an antiferromagnetic shell with varying values of the core/shell interface exchange coupling which aim to clarify the microscopic origin of exchange bias observed experimentally. We have found loop shifts in the field direction as well as displacements along the magnetization axis that increase in magnitude when increasing the interfacial exchange coupling. Overlap functions computed from the spin configurations along the loops have been obtained to explain the origin and magnitude of these features microscopically

Spinal cord arteriovenous shunts: from imaging to management

International Nuclear Information System (INIS)

Rodesch, G.; Lasjaunias, P.

2003-01-01

Spinal cord arteriovenous shunts (SCAVSs) are either fistulas or niduses that can be separated in four different groups according to their localization and relationship to the dura. Paraspinal AVSs are located outside the spine and are responsible for neurological symptoms because of cord compression by ertatic veins, venous congestion or arterial steal. Epidural shunts are located in the epidural space and drain in epidural veins with secondary intradural congestion. Dural shunts are embedded in the dura, produce a cord venous myelopathy after draining through veins that either pierce the dura far from a nerve root or accompany a nerve root. Intradural shunts affect the cord, the roots or the filum. Additionally, they can be classified according to their potential relationships with genetics, vascular biological features and angiogenesis into genetic hereditary lesions (hereditary hemorrhagic telangiectasia), genetic non-hereditary lesions (multiple lesions with metameric links) and single lesions (AVMs or micro AVFs). MRI and MRA are able to visualise SCAVS early after the onset of clinical symptoms. The type of shunt and its localization may remain difficult to be precise. Angiography remains the gold standard for analysis of the anatomical, morphological and architectural features necessary for therapeutic decisions in both paediatric and adult populations. In our series, embolisation is chosen in first intention whatever the type of shunt responsible for the clinical symptoms and glue is preferably used. In paraspinal, dural or epidural arteriovenous shunts, the goal of treatment should be complete closure of the shunt. A complete cure by embolization is rather easily achieved in paraspinal lesions. Failure of endovascular therapy in dural or epidural shunts must bring the patient to surgery. The prognosis of most intradural shunts seems better than previously thought, even after haemorrhage. In intradural spinal cord arteriovenous shunts, embolisation

Quadcopter Aggressive Maneuvers along Singular Configurations: An Energy-Quaternion Based Approach

Directory of Open Access Journals (Sweden)

Ayman A. El-Badawy

2016-01-01

Full Text Available Automatic aggressive maneuvers with quadcopters are regarded as a highly challenging control problem. The aim is to tackle the singularities that exist in a vertical looping maneuver. Modeling singularities are resolved by writing the equations-of-motion of the quadcopter in quaternion form. Physical singularities due to underactuation are resolved by using an energy-based control. Energy-based control is utilized to overcome the uncontrollability of the quadcopter at physical singular configurations, for instance, when commanding the quadcopter to gain altitude while pitched at 90∘. Three looping strategies (circular, clothoidal, and newly developed constant thrust are implemented on a nonlinear model of the quadcopter. The three looping strategies are discussed along with their advantages and limitations.

A systematic and efficient method to compute multi-loop master integrals

Science.gov (United States)

Liu, Xiao; Ma, Yan-Qing; Wang, Chen-Yu

2018-04-01

We propose a novel method to compute multi-loop master integrals by constructing and numerically solving a system of ordinary differential equations, with almost trivial boundary conditions. Thus it can be systematically applied to problems with arbitrary kinematic configurations. Numerical tests show that our method can not only achieve results with high precision, but also be much faster than the only existing systematic method sector decomposition. As a by product, we find a new strategy to compute scalar one-loop integrals without reducing them to master integrals.

Interventional therapy for priapism caused by arteriovenous fistula of penis: the nursing experience in two patients

International Nuclear Information System (INIS)

Peng Jinxia; Liu Ping; Jia Hongtao

2010-01-01

Objective: To discuss the perioperative nursing measures for interventional treatment of priapism caused by arteriovenous fistula of penis in order to reduce the operation-related complications and to promote rehabilitation. Methods: A series of nursing steps were carried out in 2 patients who suffered from priapism caused by arteriovenous fistula of penis and received interventional therapy. The nursing measures included preoperative psychological nursing,routine preoperative examinations, promotion of friendly relations between nurse and patient, preparation for the operation method, the preparation of skin, postoperative nursing of patient's position, observation of penis erection and vital signs, postoperative psychological nursing, and the health guidance at the time of discharge. Results: After the interventional therapy two patients were successfully cured at the time of discharge. No complications related to the operation occurred. Three months after the operation the erect function of the penis remained normal. Conclusion: The interventional therapy is a safe and reliable technique for priapism caused by arteriovenous fistula of penis. The proper and effective perioperative and postoperative nursing measures can surely improve the successful rate of interventional treatment as well as prevent the occurrence of complications. (authors)

Renal aneurysm and arteriovenous fistula

International Nuclear Information System (INIS)

Savastano, S.; Feltrin, G.P.; Miotto, D.; Chiesura-Corona, M.; Padua Univ.

1990-01-01

Embolization was performed in six patients with renal artery aneurysms (n=2) and arteriovenous fistulas (AVF) (n=5). The aneurysms were observed in one patient with fibromuscular dysplasia and in another with Ehlers-Danlos syndrome. All the AVFs were intraparenchymal and secondary to iatrogenic trauma. Elective embolization was performed in five patients with good clinical results at follow-up between 1 and 9 years. Because of rupture of the aneurysm emergency embolization was attempted without success in the patient with Ehlers-Danlos syndrome, and nephrectomy was carried out. A postembolization syndrome complicated three procedures in which Gelfoam and polyvinyl alcohol were used; in two of these cases unexpected reflux of the particulate material occurred, resulting in limited undesired ablation of the ipsilateral renal parenchyma. Embolization is the most reliable and effective treatment for intrarenal vascular abnormalities since it minimizes the parenchymal damage. (orig.)

Promising Poly(ε-caprolactone Composite Reinforced with Weft-Knitted Polyester for Small-Diameter Vascular Graft Application

Directory of Open Access Journals (Sweden)

Fu-Jun Wang

2014-01-01

Full Text Available The present study was designed to improve the mechanical performance of a small-diameter vascular prosthesis made from a flexible membrane of poly(ε-caprolactone (PCL. PCL reinforcement was achieved by embedding a tubular fabric knitted from polyethylene terephthalate (PET yarns within the freeze-dried composite structure. The knitting density of PET fabric influenced the mechanical properties of the new vascular graft. Results showed that the composite prototype has good mechanical properties, water permeability, elastic recovery, and suture retention strength. Increases in loop density increased compressive strength and suture retention strength and decreased elastic recovery. The new composite prototype vascular graft has promising potential applications in clinics because of its excellent mechanical properties.

Selective digital venous hypertension: A rare complication of hemodialysis arteriovenous fistula

Energy Technology Data Exchange (ETDEWEB)

Swayne, L.C.; Manstein, C.; Somers, R.; Cope, C.

1983-04-01

We report and document angiographically a case of selective venous hypertension, masquerading as an infection, which involved the three middle digits of the right hand in a patient with an access arteriovenous (AV) fistula. This complication arose following hemodialysis and was resolved after resection of the right radial artery at the site of AV fistula and re-anastomosis.

Embolization of intracranial dural arteriovenous fistulas using PHIL liquid embolic agent in 26 patients

DEFF Research Database (Denmark)

Lamin, S.; Chew, H. S.; Chavda, S.

2017-01-01

BACKGROUND AND PURPOSE: The introduction of liquid embolic agents has revolutionized endovascular approach to cranial vascular malformations. The aim of the study was to retrospectively assess the efficacy and safety of Precipitating Hydrophobic Injectable Liquid (PHIL), a new nonadhesive liquid......: This was a retrospective multicenter study. Twenty-six consecutive patients with dural arteriovenous fistulas (de novo or previously treated) treated by injection of PHIL only or with PHIL in combination with other embolization products (such as Onyx or detachable coils) were included in the study. Recruitment started......, 3 were retreated with PHIL and 1 achieved angiographic cure. An adverse event was seen in 1 patient who developed worsening of preexisting ataxia due to acute thrombosis of the draining vein. CONCLUSIONS: PHIL appears to be safe and effective for endovascular treatment of cranial dural arteriovenous...

Nanofat grafting under a split-thickness skin graft for problematic wound management.

Science.gov (United States)

Kemaloğlu, Cemal Alper

2016-01-01

Obesity and certain medical disorders make the reconstruction of skin defects challenging. Different kind of procedure can be used for these defect, besides, skin grafting is one of the most common and simplest procedure. Fat grafting and stem cells which are located in the adipose tissue have been commonly used in plastic surgery for regeneration and rejuvenation purposes. To decrease graft failure rate we performed nanofat grafting under an autologous split-thickness skin graft in our patient who had a problematic wound. The case of a 35-year-old female patient with a traumatic skin defect on her left anterior crural region is described herein. After subsequent flap reconstruction, the result was disappointing and the defect size was widened. The defect was treated with combined grafting (nanofat grafting under an autologous split-thickness skin graft). At the 6 months follow-up assessment after combined grafting, the integrity of the skin graft was good with excellent pliability. Combined grafting for problematic wounds seems to be a useful technique for cases requiring reconstruction. The potential existence of stem cells may be responsible for the successful result in our patient.

Effect of bidispersity in grafted chain length on grafted chain conformations and potential of mean force between polymer grafted nanoparticles in a homopolymer matrix.

Science.gov (United States)

Nair, Nitish; Wentzel, Nathaniel; Jayaraman, Arthi

2011-05-21

In efforts to produce polymeric materials with tailored physical properties, significant interest has grown around the ability to control the spatial organization of nanoparticles in polymer nanocomposites. One way to achieve controlled particle arrangement is by grafting the nanoparticle surface with polymers that are compatible with the matrix, thus manipulating the interfacial interactions between the nanoparticles and the polymer matrix. Previous work has shown that the molecular weight of the grafted polymer, both at high grafting density and low grafting density, plays a key role in dictating the effective inter-particle interactions in a polymer matrix. At high grafting density nanoparticles disperse (aggregate) if the graft molecular weight is higher (lower) than the matrix molecular weight. At low grafting density the longer grafts can better shield the nanoparticle surface from direct particle-particle contacts than the shorter grafts and lead to the dispersion of the grafted particles in the matrix. Despite the importance of graft molecular weight, and evidence of non-trivial effects of polydispersity of chains grafted on flat surfaces, most theoretical work on polymer grafted nanoparticles has only focused on monodisperse grafted chains. In this paper, we focus on how bidispersity in grafted chain lengths affects the grafted chain conformations and inter-particle interactions in an implicit solvent and in a dense homopolymer polymer matrix. We first present the effects of bidispersity on grafted chain conformations in a single polymer grafted particle using purely Monte Carlo (MC) simulations. This is followed by calculations of the potential of mean force (PMF) between two grafted particles in a polymer matrix using a self-consistent Polymer Reference Interaction Site Model theory-Monte Carlo simulation approach. Monte Carlo simulations of a single polymer grafted particle in an implicit solvent show that in the bidisperse polymer grafted particles

Bone grafting: An overview

Directory of Open Access Journals (Sweden)

D. O. Joshi

2010-08-01

Full Text Available Bone grafting is the process by which bone is transferred from a source (donor to site (recipient. Due to trauma from accidents by speedy vehicles, falling down from height or gunshot injury particularly in human being, acquired or developmental diseases like rickets, congenital defects like abnormal bone development, wearing out because of age and overuse; lead to bone loss and to replace the loss we need the bone grafting. Osteogenesis, osteoinduction, osteoconduction, mechanical supports are the four basic mechanisms of bone graft. Bone graft can be harvested from the iliac crest, proximal tibia, proximal humerus, proximal femur, ribs and sternum. An ideal bone graft material is biologically inert, source of osteogenic, act as a mechanical support, readily available, easily adaptable in terms of size, shape, length and replaced by the host bone. Except blood, bone is grafted with greater frequency. Bone graft indicated for variety of orthopedic abnormalities, comminuted fractures, delayed unions, non-unions, arthrodesis and osteomyelitis. Bone graft can be harvested from the iliac crest, proximal tibia, proximal humerus, proximal femur, ribs and sternum. By adopting different procedure of graft preservation its antigenicity can be minimized. The concept of bone banking for obtaining bone grafts and implants is very useful for clinical application. Absolute stability require for successful incorporation. Ideal bone graft must possess osteogenic, osteoinductive and osteocon-ductive properties. Cancellous bone graft is superior to cortical bone graft. Usually autologous cancellous bone graft are used as fresh grafts where as allografts are employed as an alloimplant. None of the available type of bone grafts possesses all these properties therefore, a single type of graft cannot be recomm-ended for all types of orthopedic abnormalities. Bone grafts and implants can be selected as per clinical problems, the equipments available and preference of

Susceptibility loci for sporadic brain arteriovenous malformation; a replication study and meta-analysis

NARCIS (Netherlands)

Kremer, P.H.; Koeleman, B.P.C.; Rinkel, G.J.; Diekstra, F.P.; Berg, L.H. van den; Veldink, J.H.; Klijn, C.J.M.

2016-01-01

BACKGROUND: Case-control studies have reported multiple genetic loci to be associated with sporadic brain arteriovenous malformations (AVMs) but most of these have not been replicated in independent populations. The aim of this study was to find additional evidence for these reported associations

Quantitative determination of peripheral arterio-venous shunts by means of radioactively labelled microspheres

International Nuclear Information System (INIS)

Friese, K.H.

1981-01-01

In the present work a nuclear method of quantitative measurement of peripheral arterio-venous shunts with a whole-body scanner is standardized. This method, developed at the beginning of the 70s at Tuebingen, stands out in contrast with earlier measuring methods by the application of the theory of quantitative scintiscanning. This means that the scintigram obtained after injection of sup(99m)technetium-labelled human albumin microspheres into an artery before the shunt is corrected for the quantitative shunt calculation by several factors using a computer, to avoid systematic mistakes. For the standardization of the method, 182 scintigrams were taken during model experiments and experiments on animals and human beings. This method, having a deviation of 10% at most, is excellently suited for the quantitative determination of peripheral arterio-venous shunts. Already for a pulmonary activity of 3% a peripheral shunt is proved with 97.5% probability. (orig./MG) [de

A systematic and efficient method to compute multi-loop master integrals

Directory of Open Access Journals (Sweden)

Xiao Liu

2018-04-01

Full Text Available We propose a novel method to compute multi-loop master integrals by constructing and numerically solving a system of ordinary differential equations, with almost trivial boundary conditions. Thus it can be systematically applied to problems with arbitrary kinematic configurations. Numerical tests show that our method can not only achieve results with high precision, but also be much faster than the only existing systematic method sector decomposition. As a by product, we find a new strategy to compute scalar one-loop integrals without reducing them to master integrals.

Cerebral arterio-venous malformations at Edgardo Rebagliati Martins Nacional Hospital

OpenAIRE

Rabanal, Jorge

2014-01-01

A review of 50 cases with cerebral arterio.venous malformations (AVM) treated since Junly 1988 through December 1992 in the Neurosurgery Service from Edgardo Rebagliati Martins National Hospital was done. Clinical records, surgical techniques and pre- and post-operative studies were evaluted by retrospective analysis. The more important results were the frecuency of presentations in male patients from the coast, the clinical onset with intracraneal hemorrhage, the operative technique of drain...

New Topological Configurations in the Continuous Heisenberg Spin Chain: Lower Bound for the Energy

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Rossen Dandoloff

2015-01-01

Full Text Available In order to study the spin configurations of the classical one-dimensional Heisenberg model, we map the normalized unit vector, representing the spin, on a space curve. We show that the total chirality of the configuration is a conserved quantity. If, for example, one end of the space curve is rotated by an angle of 2π relative to the other, the Frenet frame traces out a noncontractible loop in SO(3 and this defines a new class of topological spin configurations for the Heisenberg model.

Development of biomimetic thermoplastic polyurethane/fibroin small-diameter vascular grafts via a novel electrospinning approach.

Science.gov (United States)

Yu, Emily; Mi, Hao-Yang; Zhang, Jue; Thomson, James A; Turng, Lih-Sheng

2018-04-01

A new electrospinning approach for fabricating vascular grafts with a layered, circumferentially aligned, and micro-wavy fibrous structure similar to natural elastic tissues has been developed. The customized electrospinning collector was able to generate wavy fibers using the dynamic "jump rope" collecting process, which also solved the sample removal problem for mandrel-type collectors. In this study, natural silk fibroin and synthetic thermoplastic polyurethane (TPU) were combined at different weight ratios to produce hybrid small-diameter vascular grafts. The purpose of combining these two materials was to leverage the bioactivity and tunable mechanical properties of these natural and synthetic materials. Results showed that the electrospun fiber morphology was highly influenced by the material compositions and solvents employed. All of the TPU/fibroin hybrid grafts had mechanical properties comparable to natural blood vessels. The circumferentially aligned and wavy biomimetic configuration provided the grafts with a sufficient toe region and the capacity for long-term usage under repeated dilatation and contraction. Cell culture tests with human endothelial cells (EC) also revealed high cell viability and good biocompatibility for these grafts. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 985-996, 2018. © 2017 Wiley Periodicals, Inc.

Alveolar ridge augmentation by connective tissue grafting using a pouch method and modified connective tissue technique: A prospective study.

Science.gov (United States)

Agarwal, Ashish; Gupta, Narinder Dev

2015-01-01

Localized alveolar ridge defect may create physiological and pathological problems. Developments in surgical techniques have made it simpler to change the configuration of a ridge to create a more aesthetic and more easily cleansable shape. The purpose of this study was to compare the efficacy of alveolar ridge augmentation using a subepithelial connective tissue graft in pouch and modified connective tissue graft technique. In this randomized, double blind, parallel and prospective study, 40 non-smoker individuals with 40 class III alveolar ridge defects in maxillary anterior were randomly divided in two groups. Group I received modified connective tissue graft, while group II were treated with subepithelial connective tissue graft in pouch technique. The defect size was measured in its horizontal and vertical dimension by utilizing a periodontal probe in a stone cast at base line, after 3 months, and 6 months post surgically. Analysis of variance and Bonferroni post-hoc test were used for statistical analysis. A two-tailed P connective tissue graft proposed significantly more improvement as compare to connective tissue graft in pouch.

Peripheral arteriovenous fistula as vascular access for long-term chemotherapy.

Science.gov (United States)

Kovalyov, Oleksiy O; Kostyuk, Oleksandr G; Tkachuk, Tetyana V

To provide long-term vascular access in clinical oncology peripheral forearm veins (up to 95% of patients in Ukraine), central venous access and "complete implanted vascular systems" are used most often. Many oncology patients have contraindications to catheterization of superior vena cava. Besides, exploitation of central veins is associated with potential technical and infectious complications. The aim - to study short-term and long-term results of arteriovenous fistula exploitation as vascular access for continuous anticancer therapy. Peripheral venous bed status in 41 oncology patients taking long-term chemotherapy treatment is analyzed in the article. Doppler sonography, morphologic and immune histochemical analyses were used in the study. Doppler sonography found qualitative and quantitative changes in forearm veins at different time periods after initiation of chemotherapy in the majority of patients. The major morphologic manifestations of venous wall damage were chemical phlebitis, local or extended hardening of venous wall, venous thrombosis and extravasations with necrosis and subsequent paravasal tissue sclerosis. Alternative vascular access created in 12 patients completely met the adequacy criteria (safety, multiple use, longevity, realization of the designed therapy program). The conclusion was made about inapplicability of forearm veins for long-term administration of cytostatic agents. If it is impossible to use central veins, arteriovenous fistula can become an alternative vascular access.

LoopIng: a template-based tool for predicting the structure of protein loops.

KAUST Repository

Messih, Mario Abdel

2015-08-06

Predicting the structure of protein loops is very challenging, mainly because they are not necessarily subject to strong evolutionary pressure. This implies that, unlike the rest of the protein, standard homology modeling techniques are not very effective in modeling their structure. However, loops are often involved in protein function, hence inferring their structure is important for predicting protein structure as well as function.We describe a method, LoopIng, based on the Random Forest automated learning technique, which, given a target loop, selects a structural template for it from a database of loop candidates. Compared to the most recently available methods, LoopIng is able to achieve similar accuracy for short loops (4-10 residues) and significant enhancements for long loops (11-20 residues). The quality of the predictions is robust to errors that unavoidably affect the stem regions when these are modeled. The method returns a confidence score for the predicted template loops and has the advantage of being very fast (on average: 1 min/loop).www.biocomputing.it/loopinganna.tramontano@uniroma1.itSupplementary data are available at Bioinformatics online.

Similar degree of intimal hyperplasia in surgically detected stenotic and nonstenotic arteriovenous fistula segments: a preliminary report.

Science.gov (United States)

Duque, Juan C; Tabbara, Marwan; Martinez, Laisel; Paez, Angela; Selman, Guillermo; Salman, Loay H; Velazquez, Omaida C; Vazquez-Padron, Roberto I

2018-04-01

Intimal hyperplasia has been historically associated with improper venous remodeling and stenosis after creation of an arteriovenous fistula. Recently, however, we showed that intimal hyperplasia by itself does not explain the failure of maturation of 2-stage arteriovenous fistulas. We seek to evaluate whether intimal hyperplasia plays a role in the development of focal stenosis of an arteriovenous fistula. This study compares intimal hyperplasia lesions in stenotic and nearby nonstenotic segments collected from the same arteriovenous fistula. Focal areas of stenosis were detected in the operating room in patients (n= 14) undergoing the second-stage vein transposition procedure. The entire vein was inspected, and areas of stenosis were visually located with the aid of manual palpation and hemodynamic changes in the vein peripheral and central to the narrowing. Stenotic and nonstenotic segments were documented by photography before tissue collection (14 tissue pairs). Intimal area and thickness, intima-media thickness, and intima to media area ratio were measured in hematoxylin and eosin stained cross-sections followed by pairwise statistical comparisons. The intimal area in stenotic and nonstenotic segments ranged from 1.25 to 11.61 mm 2 and 1.29 to 5.81 mm 2 , respectively. There was no significant difference between these 2 groups (P=.26). Maximal intimal thickness (P=.22), maximal intima-media thickness (P=.13), and intima to media area ratio (P=.73) were also similar between both types of segments. This preliminary study indicates that postoperative intimal hyperplasia by itself is not associated with the development of focal venous stenosis in 2-stage fistulas. Copyright © 2017 Elsevier Inc. All rights reserved.

Pressure measurements in arterial feeders of brain arteriovenous malformations before and after endovascular embolization

International Nuclear Information System (INIS)

Henkes, H.; Gotwald, T.F.; Brew, S.; Kaemmerer, F.; Miloslavski, E.; Kuehne, D.

2004-01-01

Arteriovenous malformations (AVMs) are composed of abnormal arterial and venous vessels in the brain causing arteriovenous shunts of arterialized blood directly from pial arteries to draining veins. The hemodynamics of these lesions is not well-understood. Changes in blood flow and pressure are probably related to the natural history of AVMs and may also play a major role in AVM treatment. In this study intra-arterial pressure was measured in feeding arteries of AVMs using a microcatheter that had been placed for subsequent embolization treatment (201 measurements were performed in 95 patients before and after the embolization procedure). Results show a direct relationship between pressure changes and degree of embolization. Since pressure changes during the embolization procedure are relatively small, it seems unlikely that these changes are the direct cause of rupture and periprocedural bleedings. (orig.)

Four-dimensional computed tomography angiographic evaluation of cranial dural arteriovenous fistula before and after embolization.

Science.gov (United States)

Tian, Bing; Xu, Bing; Lu, Jianping; Liu, Qi; Wang, Li; Wang, Minjie

2015-06-01

This study aimed to evaluate the usefulness of four-dimensional CTA before and after embolization treatment with ONYX-18 in eleven patients with cranial dural arteriovenous fistulas, and to compare the results with those of the reference standard DSA. Eleven patients with cranial dural arteriovenous fistulas detected on DSA underwent transarterial embolization with ONYX-18. Four-dimensional CTA was performed an average of 2 days before and 4 days after DSA. Four-dimensional CTA and DSA images were reviewed by two neuroradiologists for identification of feeding arteries and drainage veins and for determining treatment effects. Interobserver and intermodality agreement between four-dimensional CTA and DSA were assessed. Forty-two feeding arteries were identified for 14 fistulas in the 11 patients. Of these, 36 (85.71%) were detected on four-dimensional CTA. After transarterial embolization, one patient got partly embolized, and the fistulas in the remaining 10 patients were completely occluded. The interobserver agreement for four-dimensional CTA and intermodality agreement between four-dimensional CTA and DSA were excellent (κ=1) for shunt location, identification of drainage veins, and fistula occlusion after treatment. Four-dimensional CTA images are highly accurate when compared with DSA images both before and after transarterial embolization treatment. Four-dimensional CTA can be used for diagnosis as well as follow-up of cranial dural arteriovenous fistulas in clinical settings. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

False traumatic aneurysms and arteriovenous fistulas: retrospective analysis.

Science.gov (United States)

Davidovic, Lazar B; Banzić, Igor; Rich, Norman; Dragaš, Marko; Cvetkovic, Slobodan D; Dimic, Andrija

2011-06-01

The purpose of this study was to analyze the incidence, clinical presentation, diagnosis, and treatment of false traumatic aneurysms and arteriovenous fistulas as well as the outcomes of the patients. A retrospective, 16-year survey has been conducted regarding the cases of patients who underwent surgery for false traumatic aneurysms (FTA) of arteries and traumatic arteriovenous fistulas (TAVF). Patients with iatrogenic AV fistulas and iatrogenic false aneurysms were excluded from the study. There were 36 patients with TAVF and 47 with FTA. In all, 73 (87.95%) were male, and 10 (12.05%) were female, with an average age of 36.93 years (13-82 years). In 25 (29.76%) cases TAVF and FTA appeared combat-related, and 59 (70.24%) were in noncombatants. The average of all intervals between the injury and surgery was 919. 8 days (1 day to 41 years) for FTA and 396.6 days (1 day to 9 years) for TAVF. Most of the patients in both groups were surgically treated during the first 30 days after injury. One patient died on the fourth postoperative day. There were two early complications. The early patency rate was 83.34%, and limb salvage was 100%. There were no recurrent AV fistulas that required additional operations. Because of their history of severe complications, FTA and TAV fistulas require prompt treatment. The treatment is simpler if there is only a short interval between the injury and the operation. Surgical endovascular repair is mostly indicated.

Bone Graft Alternatives

Science.gov (United States)

... Spine Treatment Spondylolisthesis BLOG FIND A SPECIALIST Treatments Bone Graft Alternatives Patient Education Committee Patient Education Committee ... procedure such as spinal fusion. What Types of Bone Grafts are There? Bone grafts that are transplanted ...

LETTER TO THE EDITOR: Arterio-venous flow between monochorionic twins determined during intra-uterine transfusion. Nonlinear decay of adult red blood cells

Science.gov (United States)

van Gemert, Martin J. C.; Pasman, Suzanne A.; van den Wijngaard, Jeroen P. H. M.; Lopriore, Enrico; Vandenbussche, Frank P. H. A.

2008-07-01

Recently, we derived equations relating the flow of adult red blood cells through a placental arterio-venous anastomosis with intra-uterine and post-natal measured adult hemoglobin concentrations. In this letter, we re-derived the equations, now including a more realistic nonlinear decay of adult red blood cells, and re-evaluated the measurement accuracy of the arterio-venous flow and the lifetime of the red blood cells.

An extended study of the phase separation between phospholipids and grafted polymers on a bilayer biomembrane

Energy Technology Data Exchange (ETDEWEB)

Benhamou, M; Joudar, I; Kaidi, H; Elhasnaoui, K; Ridouane, H; Qamar, H, E-mail: benhamou.mabrouk@gmail.com [Laboratoire de Physique des Polymeres et Phenomenes Critiques, Faculte des Sciences, Ben M' sik, PO Box 7955, Casablanca (Morocco)

2011-06-01

We re-examine here the phase separation between phospholipids and adsorbed polymer chains on a fluid membrane with a change in some suitable parameter (temperature). Our purpose is to quantify the significant effects of the solvent quality and of the polydispersity of adsorbed loops formed by grafted polymer chains on the segregation phenomenon. To this end, we elaborate on a theoretical model that allows us to derive the expression for the mixing free energy. From this, we extract the phase diagram shape in the composition-temperature plane. Our main conclusion is that the polymer chain condensation is very sensitive to the solvent quality and to the polydispersity of loops of adsorbed chains.

Graft irradiation abrogates graft-versus-host disease in combined pancreas-spleen transplantation

International Nuclear Information System (INIS)

Schulak, J.A.; Sharp, W.J.

1986-01-01

A model of combined pancreas-spleen transplantation (PST) was studied in LBN F1 recipients of Lewis grafts in order to evaluate the efficacy of pretransplant graft irradiation in preventing lethal graft-versus-host disease (GVHD). Recipients of unmodified PST uniformly developed severe GVHD and died (MST = 16.7 +/- 3.8 days). Whole body donor irradiation with either 500 or 250 rad prevented lethal GVHD. Similarly, ex vivo graft irradiation with either 1000 or 500 rad also resulted in normal weight gain, graft function, and host survival for the 6-week study period. Conversely, delay of graft irradiation until 3 days after transplantation failed to prevent this complication (MST = 15.8 +/- 3.7 days). Recipients of irradiated grafts displayed glucose tolerance tests that were identical to those in the control group indicating that the doses of radiation employed in these experiments were not deleterious to islet function. Irradiated spleen grafts appeared histologically normal at 6 weeks after transplantation. Cells derived from these grafts failed to stimulate lymph node enlargement in a popliteal lymph node assay for GVHD, suggesting that these spleens may have become repopulated with host cells. These experiments confirm that PST has the potential to cause lethal GVHD and suggest that pretransplant graft irradiation may be used to prevent its occurrence

Metallic stent placement in hemodialysis graft patients after insufficient balloon dilation

International Nuclear Information System (INIS)

Liang, Huei-Lung; Pan, Huay-Ben; Lin, Yih-Huie; Chen, Chiung-Yu; Lai, Pin-Hong; Yang, Chien-Fang; Chung, Hsiao-Min; Wu, Tung-Ho; Chou, Kang-Ju

2006-01-01

We wanted to report our experience of metallic stent placement after insufficient balloon dilation in graft hemodialysis patients. Twenty-three patients (13 loop grafts in the forearm and 10 straight grafts in the upper arm) underwent metallic stent placement due to insufficient flow after urokinase thrombolysis and balloon dilation. The indications for metallic stent deployment included 1) recoil and/or kinked venous stenosis in 21 patents (venous anastomosis: 17 patients, peripheral outflow vein: four patients); and 2) major vascular rupture in two patients. Metallic stents 8-10mm in diameter and 40-80 mm in length were used. Of them, eight stents were deployed across the elbow crease. Access patency was determined by clinical follow-up and the overall rates were calculated by Kaplan-Meier survival analysis. No procedure-related complications (stent fracture or central migration) were encountered except for a delayed Wallstent shortening/migration at the venous anastomosis, which resulted in early access failure. The overall primary and secondary patency rates (±standard error) of all the vascular accesses in our 23 patients at 3, 6, 12 and 24 months were 69%±9 and 88%±6,41% ±10 and 88%±6, 30%±10 and 77%±10, and 12%±8 and 61%±13, respectively. For the forearm and upper-arm grafts, the primary and secondary patency rates were 51%±16 and 86%±13 vs 45%±15 and 73%±13 at 6 months, and 25%±15 and 71%±17 vs 23%±17 and 73%±13 at 12 months (ρ = .436 and .224), respectively. Metallic stent placement is a safe and effective means for treating peripheral venous lesions in dialysis graft patients after insufficient balloon dilation. No statistically difference in the patency rates between the forearm and upper-arm patient groups was seen

Reliability analysis and component functional allocations for the ESF multi-loop controller design

International Nuclear Information System (INIS)

Hur, Seop; Kim, D.H.; Choi, J.K.; Park, J.C.; Seong, S.H.; Lee, D.Y.

2006-01-01

This paper deals with the reliability analysis and component functional allocations to ensure the enhanced system reliability and availability. In the Engineered Safety Features, functionally dependent components are controlled by a multi-loop controller. The system reliability of the Engineered Safety Features-Component Control System, especially, the multi-loop controller which is changed comparing to the conventional controllers is an important factor for the Probability Safety Assessment in the nuclear field. To evaluate the multi-loop controller's failure rate of the k-out-of-m redundant system, the binomial process is used. In addition, the component functional allocation is performed to tolerate a single multi-loop controller failure without the loss of vital operation within the constraints of the piping and component configuration, and ensure that mechanically redundant components remain functional. (author)

Effect of Grafting Method, Graft Cover and Foliar Spray of some Mineral Elements on Persian Walnut Graft-take and Winter Survival Rate

Directory of Open Access Journals (Sweden)

Reza Rezaee

2017-09-01

Full Text Available Introduction: Persian walnut (Juglans regia L. is an important nut crop in Iran and many parts of the world. One of the major challenges of growing walnut is planting of non-grafted walnut trees in orchards, which leads to the reduction of yield, quality and productivity of walnut orchards. Compared to the other fruit trees, walnut grafting is difficult and even newly grafted walnut seedlings are vulnerable to fall or winter frost chilling, so that most of the seedlings are lost after subjecting to the cold winter. There are a few studies reporting successful grafting in outdoor conditions, however, final grafting take after winter has been usually ignored. Hence, increased walnut grafting success and improved tree growth after grafting through foliar nutrient application may lead to increased tolerance of chilling. Therefore, main goals of this research were to investigate the effect of some graft covers and role of foliar spray of calcium, boron and zinc on the reduction of frost damage in newly grafted seedlings under outdoor conditions. Materials and methods: This research was conducted at agricultural research station, Khoy city, west Azerbaijan province, during 2012-2014. In the first experiment, three methods of grafting including cleft, bark and V-shaped, and two kinds of graft covers including moist sawdust and superabsorbent plus cotton wool were investigated in terms of grafting success and quality of seedlings. In the second experiment, effect of the three above-mentioned grafting methods and two levels of foliar spray including sequential spray of Ca (4 ppm, B and Zn (2% (3 times during growth season and control (no spray were studied in terms of frost damage. The experiments conducted in factorial based on randomized complete block design with 10 trees in each plot. Data were collected 45 days after grafting take, final grafting take after one winter, subsequent scion growth length and diameter and concentration of Ca, B and Zn in

Traumatic subclavian arteriovenous fistula in a young adult

International Nuclear Information System (INIS)

Nazario Dolz, Ana Maria; Ibannez Casero, Marlene; Rodriguez Fernandez, Zenen; Pichin Quesada, Alexis; Lopez Martin, Jose Carlos

2011-01-01

The case report of a 23 year-old patient who was admitted to the General Surgery Service of 'Saturnino Lora Torres' Provincial Teaching Clinical Surgical Hospital in Santiago de Cuba with the diagnosis of traumatic pneumothorax is described, as consequence of stab wounds in the right anterior and superior region of the thorax; but then, after 48 hours, a right subclavian arteriovenous fistula, which was proven by means of x ray was diagnosed. The postoperative clinical course was favorable and the patient was discharged after 11 days, completely asymptomatic. His working activities began 2 months later.(author)

Suction blister grafting - Modifications for easy harvesting and grafting

Directory of Open Access Journals (Sweden)

2012-01-01

Full Text Available Suction blister grafting is a simple modality of treatment of patients with resistant and stable vitiligo. But raising the blisters may be time consuming and transferring to the recipient site may be difficult as the graft is ultrathin. By doing some modifications we can make the technique simpler and easier. We can decrease the blister induction time by intradermal injection of saline, exposure to Wood′s lamp, intrablister injection of saline. By these methods we can decrease the blister induction time from 2-3 hrs to 45-90 minutes. After harvesting the graft, it can be transferred to the recipient area by taking the graft on a sterile glass slide, on the gloved finger, rolling the graft over a sterile syringe and then spreading on the recipient area, or taking on the sterile wrapper of paraffin dressing and then placing over the recipient area.

Evaluation of synthetic vascular grafts in a mouse carotid grafting model.

Science.gov (United States)

Chan, Alex H P; Tan, Richard P; Michael, Praveesuda L; Lee, Bob S L; Vanags, Laura Z; Ng, Martin K C; Bursill, Christina A; Wise, Steven G

2017-01-01

Current animal models for the evaluation of synthetic grafts are lacking many of the molecular tools and transgenic studies available to other branches of biology. A mouse model of vascular grafting would allow for the study of molecular mechanisms of graft failure, including in the context of clinically relevant disease states. In this study, we comprehensively characterise a sutureless grafting model which facilitates the evaluation of synthetic grafts in the mouse carotid artery. Using conduits electrospun from polycaprolactone (PCL) we show the gradual development of a significant neointima within 28 days, found to be greatest at the anastomoses. Histological analysis showed temporal increases in smooth muscle cell and collagen content within the neointima, demonstrating its maturation. Endothelialisation of the PCL grafts, assessed by scanning electron microscopy (SEM) analysis and CD31 staining, was near complete within 28 days, together replicating two critical aspects of graft performance. To further demonstrate the potential of this mouse model, we used longitudinal non-invasive tracking of bone-marrow mononuclear cells from a transgenic mouse strain with a dual reporter construct encoding both luciferase and green fluorescent protein (GFP). This enabled characterisation of mononuclear cell homing and engraftment to PCL using bioluminescence imaging and histological staining over time (7, 14 and 28 days). We observed peak luminescence at 7 days post-graft implantation that persisted until sacrifice at 28 days. Collectively, we have established and characterised a high-throughput model of grafting that allows for the evaluation of key clinical drivers of graft performance.

Evaluation of synthetic vascular grafts in a mouse carotid grafting model.

Directory of Open Access Journals (Sweden)

Alex H P Chan

Full Text Available Current animal models for the evaluation of synthetic grafts are lacking many of the molecular tools and transgenic studies available to other branches of biology. A mouse model of vascular grafting would allow for the study of molecular mechanisms of graft failure, including in the context of clinically relevant disease states. In this study, we comprehensively characterise a sutureless grafting model which facilitates the evaluation of synthetic grafts in the mouse carotid artery. Using conduits electrospun from polycaprolactone (PCL we show the gradual development of a significant neointima within 28 days, found to be greatest at the anastomoses. Histological analysis showed temporal increases in smooth muscle cell and collagen content within the neointima, demonstrating its maturation. Endothelialisation of the PCL grafts, assessed by scanning electron microscopy (SEM analysis and CD31 staining, was near complete within 28 days, together replicating two critical aspects of graft performance. To further demonstrate the potential of this mouse model, we used longitudinal non-invasive tracking of bone-marrow mononuclear cells from a transgenic mouse strain with a dual reporter construct encoding both luciferase and green fluorescent protein (GFP. This enabled characterisation of mononuclear cell homing and engraftment to PCL using bioluminescence imaging and histological staining over time (7, 14 and 28 days. We observed peak luminescence at 7 days post-graft implantation that persisted until sacrifice at 28 days. Collectively, we have established and characterised a high-throughput model of grafting that allows for the evaluation of key clinical drivers of graft performance.

Massive Left-sided Congestive Colitis Due to Idiopathic Inferior Mesenteric Arteriovenous Malformation

Directory of Open Access Journals (Sweden)

Laura Martí Gelonch

2017-01-01

Full Text Available Arteriovenous malformations (AVM of the inferior mesenteric artery are rare. They may be primary (congenital or idiopathic or secondary (acquired after trauma or of iatrogenic origin. Of the abdominal AVM, the inferior mesenteric trunk is the least commonly involved. Most reported cases are of iatrogenic origin, resulting from colon surgery. Only 17 cases have been described and published in the literature. The objective of this work is to make known a case treated in our center. We present a case of 73-year old male, who came to the emergency service with symptoms of abdominal distension, pain lasting 48 hours along with months of diarrhoea. CT scan and an abdominal CT angiography showed a massive left-sided congestive colitis due to idiopathic inferior mesenteric arteriovenous malformation. In our case, the decision was to carry out the treatment in two stages. Embolisation was performed in the first stage in order to decrease the blood flow and the risk of intraoperative bleeding, followed by resective surgery of the affected colon.

A Case Report of Onyx Pulmonary Arterial Embolism Contributing to Hypoxemia During Awake Craniotomy for Arteriovenous Malformation Resection.

Science.gov (United States)

Tolly, Brian T; Kosky, Jenna L; Koht, Antoun; Hemmer, Laura B

2017-02-15

A healthy 26-year-old man with cerebral arteriovenous malformation underwent staged endovascular embolization with Onyx followed by awake craniotomy for resection. The perioperative course was complicated by tachycardia and severe intraoperative hypoxemia requiring significant oxygen supplementation. Postoperative chest computed tomography (CT) revealed hyperattenuating Onyx embolization material within the pulmonary vasculature, and an electrocardiogram indicated possible right heart strain, supporting clinically significant embolism. With awake arteriovenous malformation resection following adjunctive Onyx embolization becoming increasingly employed for lesions involving the eloquent cortex, anesthesiologists need to be aware of pulmonary migration of Onyx material as a potential contributor to significant perioperative hypoxemia.

Contemporary Management of Pulmonary Arteriovenous Malformations.

Science.gov (United States)

Rauh, Nicholas; Gurley, John; Saha, Sibu

2017-12-01

Pulmonary arteriovenous malformations (PAVMs) are atypical vascular structures involving a direct connection between the pulmonary arterial and venous circulations. While PAVMs are a relatively uncommon disorder, unmanaged cases are at risk for the development of serious complications including embolization and infection. Since their first description in 1897, PAVMs have been identified and treated in a variety of ways. Advancements in diagnostic methods and operative techniques have allowed for more effective treatment of the disease. Most recently, the use of vascular plug transcatheter embolization has been described as an effective therapeutic procedure in the management of PAVMs. In this report, we present our experience with nine cases of PAVMs treated at the University of Kentucky, including special consideration of an exemplary case that illustrates the typical course of treatment for the disease.

Delayed grafting for banked skin graft in lymph node flap transfer.

Science.gov (United States)

Ciudad, Pedro; Date, Shivprasad; Orfaniotis, Georgios; Dower, Rory; Nicoli, Fabio; Maruccia, Michele; Lin, Shu-Ping; Chuang, Chu-Yi; Chuang, Tsan-Yu; Wang, Gou-Jen; Chen, Hung-Chi

2017-02-01

Over the last decade, lymph node flap (LNF) transfer has turned out to be an effective method in the management of lymphoedema of extremities. Most of the time, the pockets created for LNF cannot be closed primarily and need to be resurfaced with split thickness skin grafts. Partial graft loss was frequently noted in these cases. The need to prevent graft loss on these iatrogenic wounds made us explore the possibility of attempting delayed skin grafting. We have herein reported our experience with delayed grafting with autologous banked split skin grafts in cases of LNF transfer for lymphoedema of the extremities. Ten patients with International Society of Lymphology stage II-III lymphoedema of upper or lower extremity were included in this study over an 8-month period. All patients were thoroughly evaluated and subjected to lymph node flap transfer. The split skin graft was harvested and banked at the donor site, avoiding immediate resurfacing over the flap. The same was carried out in an aseptic manner as a bedside procedure after confirming flap viability and allowing flap swelling to subside. Patients were followed up to evaluate long-term outcomes. Flap survival was 100%. Successful delayed skin grafting was done between the 4th and 6th post-operative day as a bedside procedure under local anaesthesia. The split thickness skin grafts (STSG) takes more than 97%. One patient needed additional medications during the bedside procedure. All patients had minimal post-operative pain and skin graft requirement. The patients were also reported to be satisfied with the final aesthetic results. There were no complications related to either the skin grafts or donor sites during the entire period of follow-up. Delayed split skin grafting is a reliable method of resurfacing lymph node flaps and has been shown to reduce the possibility of flap complications as well as the operative time and costs. © 2016 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Skin Graft

OpenAIRE

Shimizu, Ruka; Kishi, Kazuo

2012-01-01

Skin graft is one of the most indispensable techniques in plastic surgery and dermatology. Skin grafts are used in a variety of clinical situations, such as traumatic wounds, defects after oncologic resection, burn reconstruction, scar contracture release, congenital skin deficiencies, hair restoration, vitiligo, and nipple-areola reconstruction. Skin grafts are generally avoided in the management of more complex wounds. Conditions with deep spaces and exposed bones normally require the use o...

Intracranial dural arterio-venous fistula presenting with progressive myelopathy.

LENUS (Irish Health Repository)

Ogbonnaya, Ebere Sunny

2011-01-01

Spinal dural arterio-venous fistula (DAVF) is rare and usually involves the thoracic segments. The classical presentation is a slowly progressive ataxia. Clinical presentation of intracranial DAVF depends on the site of the DAVF, as well as the vessels involved. Patients may present with pulsatile tinnitus, occipital bruit, headache, dementia, visual impairment as well as neurological deterioration distant from the DAVF as a result of venous hypertension and cortical haemorrhage. The authors present a rare case of progressive myelopathy secondary to an intracranial DAVF.

Stereotactic radiosurgery for deep intracranial arteriovenous malformations, part 1: Brainstem arteriovenous malformations.

Science.gov (United States)

Cohen-Inbar, Or; Ding, Dale; Chen, Ching-Jen; Sheehan, Jason P

2016-02-01

The management of brainstem arteriovenous malformations (AVM) are one of the greatest challenges encountered by neurosurgeons. Brainstem AVM have a higher risk of hemorrhage compared to AVM in other locations, and rupture of these lesions commonly results in devastating neurological morbidity and mortality. The potential morbidity associated with currently available treatment modalities further compounds the complexity of decision making for affected patients. Stereotactic radiosurgery (SRS) has an important role in the management of brainstem AVM. SRS offers acceptable obliteration rates with lower risks of hemorrhage occurring during the latency period. Complex nidal architecture requires a multi-disciplinary treatment approach. Nidi partly involving subpial/epipial regions of the dorsal midbrain or cerebellopontine angle should be considered for a combination of endovascular embolization, micro-surgical resection and SRS. Considering the fact that incompletely obliterated lesions (even when reduced in size) could still cause lethal hemorrhages, additional treatment, including repeat SRS and surgical resection should be considered when complete obliteration is not achieved by first SRS. Patients with brainstem AVM require continued clinical and radiological observation and follow-up after SRS, well after angiographic obliteration has been confirmed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Study on introduction of SN transition type FCL into looped distribution system

International Nuclear Information System (INIS)

Kameda, Hideyuki; Uemura, Satoshi; Ichinose, Ataru

2012-01-01

A large amount of distributed generations such as PV will be introduced into the future Japanese distribution systems. Although distribution systems are presently operated under radial configuration and are terminated with loads, the connection of the distributed generations may cause some problems such as the occurrence of reverse power, the sensitivity decrease of the protection relays, and the voltage rise at the ends. It is assumed that a distribution system is looped in a large city to aim at the improvement of the service reliability under the situation mentioned above. However, a countermeasure against the increase of short-circuit current may be necessary in a looped system. We think that the installation of the SN transition type superconducting fault current limiter (FCL) is effective as a measure against the increase of short-circuit capacity, so we have proposed an effective arrangement of the FCLs into a radial distribution system and the method of setting the parameters. In this paper, a new introduction of FCLs is proposed, that is the way to clear a short-circuit fault within a looped system by the protection relay and the loop switch (LS). To achieve this purpose, the FCL needs to reduce the current through the LS below the rated current of the LS. And we propose the best arrangement to achieve the purpose, and the method of setting the parameters of a SN transition type FCL. Our proposal may bring the flexibility of composing any system configuration.

Loop quantum gravity in asymptotically flat spaces

International Nuclear Information System (INIS)

Arnsdorf, M.

2000-01-01

This thesis describes applications and extensions of the loop variable approach to non-perturbative quantum gravity. The common theme of the work presented, is the need to generalise loop quantum gravity to be applicable in cases where space is asymptotically flat, and no longer compact as is usually assumed. This is important for the study of isolated gravitational systems. It also presents a natural context in which to search for the semi-classical limit, one of the main outstanding problems in loop quantum gravity. In the first part of the thesis we study how isolated gravitational systems can be attributed particle-like properties. In particular, we show how spinorial states can arise in pure loop quantum gravity if spatial topology is non-trivial, thus confirming an old conjecture of Friedman and Sorkin. Heuristically, this corresponds to the idea that we can rotate isolated regions of spatial topology relative to the environment at infinity, and that only a 4π-rotation will take us back to the original configuration. To do this we extend the standard loop quantum gravity formalism by introducing a compactification of our non-compact spatial manifold, and study the knotting of embedded graphs. The second part of the thesis takes a more systematic approach to the study of loop quantum gravity on non-compact spaces. We look for new representations of the loop algebra, which give rise to quantum theories that are inequivalent to the standard one. These theories naturally describe excitations of a fiducial background state, which is specified via the choice of its vacuum expectation values. In particular, we can choose background states that describe the geometries of non-compact manifolds. We also discuss how suitable background states can be constructed that can approximate classical phase space data, in our case holonomies along embedded paths and geometrical quantities related to areas and volumes. These states extend the notion of the weave and provide a

Embolization of Uterine Arteriovenous Malformations Associated with Cyanotic Congenital Heart Disease

International Nuclear Information System (INIS)

Wijesekera, N. T.; Padley, S. P.; Kazmi, F.; Davies, C. L.; McCall, J. M.

2009-01-01

Uterine arteriovenous malformation (AVM) is a rare cause of vaginal bleeding and miscarriage. We report two cases of uterine AVMs in patients with a history of complex congenital heart disease, an association that has not been previously described. Both patients were treated by selective uterine artery embolization, a minimally invasive therapy that has revolutionized the management of uterine AVMs, thus offering an alternative to conventional hysterectomy.

Extension of Loop Quantum Gravity to Metric Theories beyond General Relativity

International Nuclear Information System (INIS)

Ma Yongge

2012-01-01

The successful background-independent quantization of Loop Quantum Gravity relies on the key observation that classical General Relativity can be cast into the connection-dynamical formalism with the structure group of SU(2). Due to this particular formalism, Loop Quantum Gravity was generally considered as a quantization scheme that applies only to General Relativity. However, we will show that the nonperturbative quantization procedure of Loop Quantum Gravity can be extended to a rather general class of metric theories of gravity, which have received increased attention recently due to motivations coming form cosmology and astrophysics. In particular, we will first introduce how to reformulate the 4-dimensional metric f(R) theories of gravity, as well as Brans-Dicke theory, into connection-dynamical formalism with real SU(2) connections as configuration variables. Through these formalisms, we then outline the nonpertubative canonical quantization of the f(R) theories and Brans-Dicke theory by extending the loop quantization scheme of General Relativity.

Evaluation of Replacement Grafts and Punch Grafts in the Treatment of Vitiligo

Directory of Open Access Journals (Sweden)

Singh Ajit Kumar

1980-01-01

Full Text Available Thirtycasesof vitiligo eachwithminimum of two lesions undent replacement graft and multiple punch grafts in one lesion each. Complications observed at the recipient site like infection and raised nigosed surface were significantly more in replacement grafts. Hypopigmentation of the graft was significantly more when the disease was progressive.

Progressive subcortical calcifications secondary to venous hypertension in an intracranial dural arteriovenous fistula.

Science.gov (United States)

Pascoe, Heather M; Lui, Elaine H; Mitchell, Peter; Gaillard, Frank

2017-05-01

Intracranial dural arteriovenous fistulas (dAVF) are acquired lesions, with the most commonly reported findings on CT haemorrhage or focal oedema. We describe a case of progressive subcortical calcification on CT secondary to venous hypertension from a high grade dAVF. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simulations of magnetic hysteresis loops for dual layer recording media

Science.gov (United States)

Fal, T. J.; Plumer, M. L.; Whitehead, J. P.; Mercer, J. I.; van Ek, J.; Srinivasan, K.

2013-05-01

A Kinetic Monte-Carlo algorithm is applied to examine MH loops of dual-layer magnetic recording media at finite temperature and long time scales associated with typical experimental measurements. In contrast with standard micromagnetic simulations, which are limited to the ns-μs time regime, our approach allows for the direct calculation of magnetic configurations over periods from minutes to years. The model is used to fit anisotropy and coupling parameters to experimental data on exchange-coupled composite media which are shown to deviate significantly from standard micromagnetic results. Sensitivities of the loops to anisotropy, inter-layer exchange coupling, temperature, and sweep rate are examined.

The MDCT and MRI Findings of a Pancreatic Arteriovenous Malformation Combined with Isolated Dissection of the Superior Mesenteric Artery: A Case Report

Energy Technology Data Exchange (ETDEWEB)

Kim, Yong Soo; Jeong, Woo Kyoung [Hanyang University Guri Hospital, Seoul (Korea, Republic of); Kim, Jin Oo [Naval Pohang Hospital, Pohang (Korea, Republic of); Oh, Ji Young; Song, Soon Young [Hanyang University Medical College, Seoul (Korea, Republic of)

2010-03-15

Pancreatic arteriovenous malformation and isolated spontaneous dissection of the superior mesenteric artery are both rare maladies, and now they can be easily diagnosed due to the development of such noninvasive modalities as multi-detector computed tomography and magnetic resonance imaging. We report here on the multi-detector computed tomography and magnetic resonance imaging findings of a rare case of pancreatic arteriovenous malformation combined with isolated dissection of the superior mesenteric artery.

The MDCT and MRI Findings of a Pancreatic Arteriovenous Malformation Combined with Isolated Dissection of the Superior Mesenteric Artery: A Case Report

International Nuclear Information System (INIS)

Kim, Yong Soo; Jeong, Woo Kyoung; Kim, Jin Oo; Oh, Ji Young; Song, Soon Young

2010-01-01

Pancreatic arteriovenous malformation and isolated spontaneous dissection of the superior mesenteric artery are both rare maladies, and now they can be easily diagnosed due to the development of such noninvasive modalities as multi-detector computed tomography and magnetic resonance imaging. We report here on the multi-detector computed tomography and magnetic resonance imaging findings of a rare case of pancreatic arteriovenous malformation combined with isolated dissection of the superior mesenteric artery

Analysis of first and second order binary quantized digital phase-locked loops for ideal and white Gaussian noise inputs

Science.gov (United States)

Blasche, P. R.

1980-01-01

Specific configurations of first and second order all digital phase locked loops are analyzed for both ideal and additive white gaussian noise inputs. In addition, a design for a hardware digital phase locked loop capable of either first or second order operation is presented along with appropriate experimental data obtained from testing of the hardware loop. All parameters chosen for the analysis and the design of the digital phase locked loop are consistent with an application to an Omega navigation receiver although neither the analysis nor the design are limited to this application.

Supercritical CO2 test loop operation and first test results

International Nuclear Information System (INIS)

Wright, Steven A.; Pickard, Paul S.

2009-01-01

The DOE Office of Nuclear Energy is investigating advanced Brayton cycles for use with next generation nuclear power plants. The focus of this work is on the supercritical CO 2 Brayton cycle which has the potential for high efficiency, and for reduced capital costs due to very compact turbomachinery. Sandia has fabricated and is operating a supercritical CO 2 (S-CO 2 ) test loop to investigate the key technology issues associated with this cycle. This loop is part of a multi-year phased development program to develop a megawatt (MW) class closed S-CO 2 Brayton cycle to demonstrate the applicability of this cycle for DOE Gen-IV program. The current loop has been configured as both a compression loop and as simple heated but unrecuperated Brayton cycle. A second split-flow or re-compression Brayton cycle is currently under development that will use approximately 1 MW of heat to run the Brayton cycle. Early configurations of this split-flow Brayton cycle will be operational later this fiscal year. The key issues for this cycle include the fundamental issues of compressor fluid performance and system control near the critical point, but also the supporting technology issues of bearings, sealing technologies, and rotor windage losses which are also essential to achieving efficiency and cost objectives. These tests are providing the first measurements and information on these key supercritical CO 2 power conversion systems questions. Important data for all these issues has been obtained. This report presents the major results of the testing by showing and comparing the measured compressor performance map with the predicted performance. The compression loop uses a ∼50 kWe motor driven compressor to spin a 37 mm OD compressor at design speeds up to 75,000 rpm with a pressure ratio of 1.8 and a flow rate of 3.53 kg/s for a compressor inlet condition of 305.3 K and 7690 kPa. The most recent configuration of this loop has added a small turbine and 260 kW of heater power is

Magnetic fields with photon beams: Use of circular current loops

International Nuclear Information System (INIS)

Jette, David

2001-01-01

Strong transverse magnetic fields can produce very large dose enhancements and reductions in localized regions of a patient under irradiation by a photon beam. Through EGS4 Monte Carlo simulations, we have examined the effects of applying a magnetic field produced by a pair of circular current loops to a photon beam penetrating a water phantom of finite thickness. We have indeed found very substantial localized dose enhancements, albeit with no corresponding dose reduction just distal to the region of dose enhancement. (However, dose reduction does occur near the distal end of the phantom.) We have also observed two phenomena to be concerned with, for this configuration: significant broadening of the penumbra close to the current loop, and narrowness of the enhanced dose region in a plane parallel to the planes of the loops. We have also examined the use of a single current loop to produce the magnetic field, and have found great asymmetry in the dose distribution; this asymmetry appears to make it impossible to treat with a single circular magnet a tumor of large dimension extending below the application surface

Conformal anomaly of generalized form factors and finite loop integrals

Science.gov (United States)

Chicherin, Dmitry; Sokatchev, Emery

2018-04-01

We reveal a new mechanism of conformal symmetry breaking at Born level. It occurs in generalized form factors with several local operators and an on-shell state of massless particles. The effect is due to hidden singularities on collinear configurations of the momenta. This conformal anomaly is different from the holomorphic anomaly of amplitudes. We present a number of examples in four and six dimensions. We find an application of the new conformal anomaly to finite loop momentum integrals with one or more massless legs. The collinear region around a massless leg creates a contact anomaly, made visible by the loop integration. The anomalous conformal Ward identity for an ℓ-loop integral is a 2nd-order differential equation whose right-hand side is an (ℓ - 1)-loop integral. It could serve as a new useful tool to find/test analytic expressions for conformal integrals. We illustrate this point with several examples of known integrals. We propose a new differential equation for the four-dimensional scalar double box.

The use of arteriovenous anastomosis for venous drainage during Tamai zone I fingertip replantation.

Science.gov (United States)

Wu, Fei; Shen, Xiaofang; Eberlin, Kyle R; Sun, Zhibo; Zhou, Xiao; Xue, Mingyu

2018-03-27

The purpose of this study was to evaluate outcomes for patients sustaining a distal fingertip amputation who underwent replantation witharteriovenous anastomosis for venous drainage over a one year period at our institution. This technique has been utilized when insufficient veins are identified in the amputated part for standard veno-venous anastomosis. A retrospective study was performed on patients presenting from 2013 to 2014. Guillotine, crush, and avulsion/degloving injuries were included if they underwent fingertip (Tamai Zone I) replantation with arterial anastomosis for vascular inflow and arteriovenous anastomosis for venous drainage. The cases were further classified as Ishikawa subzone I and subzone II. Arteriovenous anastomosis for venous drainage during replantation was used in 45 digits in 35 patients. 41 of the 45 digits underwent successful replantation using this technique (91%). The mean active ROM in the DIP joint of the fingers and in the IP joint of thumbs was 65° and 57°, respectively. Sensory evaluation demonstrated a mean of 6.9 mm s2PD in digits where the digital nerves could be repaired. 11 replanted digits without nerve repair regained some sensory recovery with a mean of 9.6 mm s2PD. 91% of patients were highly satisfied with the appearance of the replanted digits based on Tamai criteria. Arteriovenous anastomosis for venous outflow should be considered during zone I fingertip replantation if sufficient veins are not identified in the amputated part. This technique may allow for more routine and successful distal replantation. Copyright © 2018 Elsevier Ltd. All rights reserved.

On the Loop Current Penetration into the Gulf of Mexico

Science.gov (United States)

Weisberg, Robert H.; Liu, Yonggang

2017-12-01

The Gulf of Mexico Loop Current generally intrudes some distance into the Gulf of Mexico before shedding an anticyclonic eddy and retreating back to its more direct entry to exit pathway. The control of this aperiodic process remains only partially known. Here we describe the evolution of the Loop Current throughout the era of satellite altimetry, and offer a mechanistic hypothesis on Loop Current intrusion. As a complement to the known effects of Loop Current forcing on the west Florida shelf circulation, we argue that the west Florida shelf, in turn, impacts the Loop Current evolution. A Self-Organizing Map analysis shows that anomalous northward penetrations of the Loop Current into the Gulf of Mexico occur when the eastern side of Loop Current is positioned west from the southwest corner of the west Florida shelf, whereas the more direct inflow to outflow route occurs when the eastern side of the Loop Current comes in contact with the southwest corner of the west Florida shelf. In essence, we argue that the west Florida shelf anchors the Loop Current in its direct path configuration and that farther northward penetration into the Gulf of Mexico occurs when such anchoring is released. To test of this hypothesis heuristically, we estimate that the dissipation and buoyancy work due to known Loop Current forcing of the west Florida shelf circulation (when in contact with the southwest corner) may exceed the pressure work required for the Loop Current to advance against the ambient Gulf of Mexico fluid.Plain Language SummaryThe Gulf of Mexico Loop Current may intrude far into the Gulf of Mexico or take a more direct entry to exit pathway. Such Loop Current behaviors are described using remote observations by satellites, and a heuristic hypothesis on the control of Loop Current intrusion is presented. We argue that energy dissipation and buoyancy work by the west Florida shelf circulation, when the Loop Current contacts the southwest corner of the west Florida shelf

Treatment of arteriovenous malformations with stereotactic radiosurgery employing both magnetic resonance angiography and standard angiography as a database

International Nuclear Information System (INIS)

Petereit, D.; Mehta, M.; Turski, P.; Levin, A.; Strother, C.; Mistretta, C.; Mackie, R.; Gehring, M.; Kubsad, S.; Kinsella, T.

1993-01-01

Twenty-one arteriovenous malformations were prospectively evaluated using magnetic resonance angiography, compare it to stereotactic angiography, employ magnetic resonance angiography in follow-up, and semiquanitfy flow. A correlative evaluation between flow and response to stereotactic radiosurgery was carried out. Phase contrast angiograms were obtained at flow velocities of 400, 200, 100, 60 and 20 cm/sec. The fractionated velocities provided images that selectively demonstrated the arterial and venous components of the arteriovenous malformations. Qualitative assessment of the velocity within the arteriovenous malformations and the presence of fistulae were also determined by multiple velocity images. In addition, 3-dimensional time-of-flight magnetic resonance angiograms were obtained to define the exact size and shape of the nidus. This technique also permitted evaluation of the nidus and feeding arteries for the the presence of low flow aneurysms. Correlation between the two imaging modalities was carried out by subjective and semiquantitative estimation of flow velocity and estimation of nidus size. The following velocity parameters were employed: fast, intermediate, slow, and none. Early analysis suggests that slower flowing arteriovenous malformations may obliterate faster after stereotactic radiosurgery an flow parameters should be employed to predict response. In conclusion, magnetic resonance angiography permits semiquantitative flow velocity assessment and may therefore be superior to stereotactic angiography. An additional advantage of magnetic resonance angiography is the generation of serial transverse images which can replace the conventional CT scan employed for stereotactic radiosurgery treatment planning. A single diagnostic test may therefore be used for diagnosis, radiosurgical treatment planning, follow-up, and treatment selection by identifying patients likely to respond early to radiosurgical management

Feasibility of the Use of RapiGraft and Skin Grafting in Reconstructive Surgery

Directory of Open Access Journals (Sweden)

Jung Dug Yang

2016-09-01

Full Text Available BackgroundSkin grafting is a relatively simple and thus widely used procedure. However, the elastic and structural quality of grafted skin is poor. Recently, various dermal substitutes have been developed to overcome this disadvantage of split-thickness skin grafts. The present study aims to determine the feasibility of RapiGraft as a new dermal substitute.MethodsThis prospective study included 20 patients with partial- or full-thickness skin defects; the patients were enrolled between January 2013 and March 2014. After skin defect debridement, the wound was divided into two parts by an imaginary line. Split-thickness skin grafting alone was performed on one side (group A, and RapiGraft and split-thickness skin grafting were used on the other side (group B. All patients were evaluated using photographs and self-questionnaires. The Manchester scar scale (MSS, a chromameter, and a durometer were used for the scar evaluation. The average follow-up period was 6 months.ResultsThe skin graft take rates were 93% in group A and 89% in group B, a non-significant difference (P=0.082. Statistically, group B had significantly lower MSS, vascularity, and pigmentation results than group A (P<0.05 for all. However, the groups did not differ significantly in pliability (P=0.155.ConclusionsThe present study indicates that a simultaneous application of RapiGraft and a split-thickness skin graft is safe and yields improved results. Therefore, we conclude that the use of RapiGraft along with skin grafting will be beneficial for patients requiring reconstructive surgery.

Chloroanthraquinone as a grafted probe molecule to investigate grafting yield on carbon powder

International Nuclear Information System (INIS)

Le Comte, Annaïg; Brousse, Thierry; Bélanger, Daniel

2016-01-01

Spontaneous grafting of chloroanthraquinone (ClAQ) groups on Black Pearls carbon by reduction of the corresponding in-situ generated diazonium cations was successfully achieved. The presence of an halogen atom on the quinone molecule allowed the use of different spectroscopic characterization techniques to determine the accurate quinone content of the modified carbon. Electrochemical characterization highlighted that the presence of chlorine atom on the grafted molecule did not affect the electrochemical response or the grafting reaction efficiency. The amount of ClAQ molecules at the carbon surface after grafting was determined by cyclic voltammetry, together with thermogravimetric analysis coupled mass spectroscopy, X-ray photoelectron spectroscopy and elemental analysis. The ClAQ mass loadings estimated from the four techniques are in very good agreement and confirm that the grafted moieties are all electrochemically active and accessible. Finally, the grafting of quinone-type molecule using the reduction of diazonium cations does not affect the electroactivity of the grafted groups and cyclic voltammetry can be considered as a reliable technique to evaluate the mass loading of grafted quinone groups on porous carbon. Thus ClAQ can be used as a grafted probe molecule to investigate grafting yield on carbon powder, and this approach can be extended to functionalized electrodes used in an increasing number of electrochemical energy storage devices.

Cartilage grafting in facial reconstruction with special consideration of irradiated grafts

International Nuclear Information System (INIS)

Donald, P.J.

1986-01-01

The search for the perfect facial implant for reconstruction of the face continues. Cartilage, once thought to be an undesirable graft material because of its propensity for absorption, has regained popularity in the past decade. Various preparation techniques have been employed to ensure graft sterility and diminished absorption. An improved understanding of cartilage structure and physiology has shed considerable light on the host-graft relationship. Gamma irradiation is a time-honored method of preservation. An experiment was undertaken to investigate the physiology of irradiated cartilage grafts following prolonged implantation on the facial skeleton of sheep and dog. Merthiolate preserved grafts were used as controls. Direct observation, histochemical techniques, autoradiography, and transmission electron micrography were used to determine chondrocyte viability and matrix composition. It was surprising to note that following implantation of 16 to 72 months, complete resorption was seen in 87.7% of the irradiated grafts and in 43.8% of the Merthiolate stored controls. Many of the grafts acquired chondrocytes from the host and produced new proteoglycan matrix as well as undergoing some degree of ossification. A comparison to the clinical situation in humans is made. 98 references

Energy Conversion Advanced Heat Transport Loop and Power Cycle

Energy Technology Data Exchange (ETDEWEB)

Oh, C. H.

2006-08-01

The Department of Energy and the Idaho National Laboratory are developing a Next Generation Nuclear Plant (NGNP) to serve as a demonstration of state-of-the-art nuclear technology. The purpose of the demonstration is two fold 1) efficient low cost energy generation and 2) hydrogen production. Although a next generation plant could be developed as a single-purpose facility, early designs are expected to be dual-purpose. While hydrogen production and advanced energy cycles are still in its early stages of development, research towards coupling a high temperature reactor, electrical generation and hydrogen production is under way. Many aspects of the NGNP must be researched and developed in order to make recommendations on the final design of the plant. Parameters such as working conditions, cycle components, working fluids, and power conversion unit configurations must be understood. Three configurations of the power conversion unit were demonstrated in this study. A three-shaft design with 3 turbines and 4 compressors, a combined cycle with a Brayton top cycle and a Rankine bottoming cycle, and a reheated cycle with 3 stages of reheat were investigated. An intermediate heat transport loop for transporting process heat to a High Temperature Steam Electrolysis (HTSE) hydrogen production plant was used. Helium, CO2, and an 80% nitrogen, 20% helium mixture (by weight) were studied to determine the best working fluid in terms cycle efficiency and development cost. In each of these configurations the relative component size were estimated for the different working fluids. The relative size of the turbomachinery was measured by comparing the power input/output of the component. For heat exchangers the volume was computed and compared. Parametric studies away from the baseline values of the three-shaft and combined cycles were performed to determine the effect of varying conditions in the cycle. This gives some insight into the sensitivity of these cycles to various

Intracranial arteriovenous malformation. Contralateral steal phenomena

Energy Technology Data Exchange (ETDEWEB)

Batjer, H H; Devous, M D; Seibert, G B; Purdy, P D; Ajmani, A K; Delarosa, M; Bonte, F J [Texas Univ., Dallas, TX (USA). Southwestern Medical Center

1989-05-01

Sixty-two patients with radiographically proven intracranial arteriovenous malformations underwent preoperative regional cerebral blood flow measurement with {sup 133}Xe signal-photon emission computed tomography. Contralateral regions of hypoperfusion were deteceted in all cases. Steal severity was assessed according to the contralateral steal index (ISteal(c)). ISteal(c) was < 0.7 (severe) in 22 (35%), 0.7-0.8 (intermediate) in 18 (29%), and > 0.8 (mild) in 22 (35%). ISteal(c) was more frequently severe or mild in females and more often intermediate in males in males (p < 0.05). Hyperemic complications were encountered more frequently in patients with intermediate ISteal(c) (p = 0.086). An unfavorable outcome was associated with less severe contralateral steal (p = 0.12). A detailed clinical, radiographic, and hemodynamic profile may help to preperatively identify patients at high risk for a poor surgical outcome. (author).

A rare cause of progressive paraparesis and urinary retention: Spinal dural arteriovenous fistula- Case report

Directory of Open Access Journals (Sweden)

Sırma Geyik

2016-12-01

Full Text Available Spinal arteriovenous fistulas (AVF, are rarely seen clinical pathology, have serious morbidity in cases without treatment although spinal AVF are the most common types of spinal arteriovenous malformation. Fifty years old male patient suffered from urine retention and paraparesis after lifted a heavy object. Spinal magnetic resonance images (MRI showed diffuse hyper intense lesion from midthoracic spinal cord segment to conus medullaris in T2A sequance. Spinal angiography revealed a long segmental dorsal AVF on the right side of T 7-8 level in spinal cord. Because of the low flow and a small AVF neurosurgical Department decided to perform an operation for spinal AVF. We should keep in mind spinal AVF, in which prognosis is well after prompt and appropriate theraphy, as a differential diagnosis in patients presented with progressive spinal symptoms.

Radiosurgery of arteriovenous malformations

International Nuclear Information System (INIS)

Kawamoto, Shunsuke

1994-01-01

Steiner has first published a report of a case of cerebral arteriovenous malformation (AVM) treated with gamma knife radiosurgery in 1972. Since the mid-1980s, radiosurgery has increasingly received much attention. There have already been more than 6,000 radiosurgically treated AVM cases. This article reviews radiosurgery in the context of the following: (1) radiosurgery according to gamma knife, linear accelerator, heavy-charged particle Bragg-peak radiation and neutron; (2) therapeutic outcome in view of angiographically proven complete obliteration (CO) of AVM, including the time required for CO and factors regulating CO (such as the volume of AVM, radiation doses, correlation between the volume of AVM and radiation doses, age, and site of AVM), histopathological findings, and clinical complaints (such as headache and epilepsy) after radiosurgery; (3) bleeding after radiosurgery; (4) complications (including angiography-related complications, those immediately after radiosurgery, delayed complications, factors influencing delayed complications, and endocrine or growth retardation); (5) other problems (such as radiation doses, follow-up strategy, approaches to giant AVMs, and repeat irradiation); (6) indication of radiosurgery for lesions other than brain stem, and lesions of the mid-brain, pons and bulb. (N.K.) 134 refs

Arteriovenous malformation of face

Directory of Open Access Journals (Sweden)

Ashok Kumar

2017-01-01

Full Text Available Arteriovenous malformations (AVMs are rare congenital vascular malformations accounting only 1.5% of all vascular anomalies with 50% occurrence in the oral and maxillofacial region. It usually results from birth defects of the vasculature. A literature search revealed only few case reports of AVMs in the facial region. Lack of meticulous diagnosis, scarcity of knowledge, and paucity of literature can result in their exsanguinations leading to fatal hemorrhagic incidents after various dental procedures such as tooth extraction, surgical intervention, puncture wound, or blunt injury in involved area. The present case describes the accidental diagnosis of asymptomatic high-flow AVMs in the facial region of pediatric patient reported primarily for the treatment of periapical abscess. This case report is unique because although there was no history of bleeding episodes, thorough examination and investigations diagnosed it as high-flow vascular malformation. It is important for the dental practitioner to be aware of AVM which may be present in the head and neck region that can produce fatal bleeding episodes during various dental procedures. Proper diagnosis of AVMs through complete history, precise clinical examination, and advanced imaging modalities can help in preventing serious life-threatening complications.

Vascular access for hemodialysis. Patency rates and results of revision.

Science.gov (United States)

Palder, S B; Kirkman, R L; Whittemore, A D; Hakim, R M; Lazarus, J M; Tilney, N L

1985-08-01

Over a 4-year interval, 324 arteriovenous conduits were created in 256 patients with end-stage renal disease as access for chronic hemodialysis. These included 154 Cimino fistulae, 163 polytetrafluoroethylene (PTFE) grafts, and seven miscellaneous grafts. Satisfactory patency rates were demonstrated for as long as 4 years for both Cimino fistulae and PTFE grafts by life-table analysis. Failures of Cimino fistulae usually occurred early in the postoperative period, secondary to attempts to use inadequate veins. Thrombosis caused the majority of PTFE graft failures and was generally the result of venous stenosis. Correction of such venous stenosis is mandatory to restore graft patency and can result in prolonged graft survival.

Transvenous sclerotherapy of peripheral arteriovenous malformations and hemangiomas

International Nuclear Information System (INIS)

Hunter, D.W.; Moradian, G.P.; Castaneda-Zuniga, W.R.; Amplantz, K.

1989-01-01

After exsanguination of the lesion and control of arterial inflow and venous outflow, the authors used a transvenous or direct puncture technique for injection of a sclerosing solution (3% sotradecol and ionic contrast material) to treat 18 patients with peripheral arteriovenous malformations or hemangiomas. The results are discussed. Good results were achieved in 12 patients. The other six patients had residual symptoms. Multiple treatment sessions were usually necessary. Short-term management included the use of intravenous heparin, steroids, and antibiotics. No significant long-term complications occurred. Short-term complications, including swelling, local pain, blistering, and localized deep venous thrombosis, occurred in 70% of the patients

Looped star polymers show conformational transition from spherical to flat toroidal shapes.

Science.gov (United States)

Reiss, Pascal; Fritsche, Miriam; Heermann, Dieter W

2011-11-01

Inspired by the topological organization of the circular Escherichia coli chromosome, which is compacted by separate domains, we study a polymer architecture consisting of a central ring to which either looped or linear side chains are grafted. A shape change from a spherical to a toroidal organization takes place as soon as the inner ring becomes large enough for the attached arms to fit within its circumference. Building up a torus, the system flattens, depending on the effective bending rigidity of the chain induced by entropic repulsion of the attached loops and, to a lesser extent, linear arms. Our results suggest that the natural formation of a toroidal structure with a decreased amount of writhe induced by a specific underlying topology could be one driving force, among others, that nature exploits to ensure proper packaging of the genetic material within a rod-shaped, bacterial envelope.

Association of vascular access flow with short-term and long-term mortality in chronic haemodialysis patients: a retrospective cohort study

OpenAIRE

Wu, Chung-Kuan; Wu, Chia-Lin; Lin, Chia-Hsun; Leu, Jyh-Gang; Kor, Chew-Teng; Tarng, Der-Cherng

2017-01-01

Objectives To investigate the impact of vascular access flow (Qa) on vascular and all-cause mortality in chronic haemodialysis (HD) patients. Design Observational cohort study. Setting Single centre. Participants Adult chronic HD patients at the HD unit of Shin Kong Wu Ho-Su Memorial Hospital between 1 January 2003 and 31 December 2003 were recruited. Patients were excluded if they had arteriovenous fistula or arteriovenous graft failure within 3 months before the date of Qa measurement, were...

On the Occurrence of Thermal Nonequilibrium in Coronal Loops

Science.gov (United States)

Froment, C.; Auchère, F.; Mikić, Z.; Aulanier, G.; Bocchialini, K.; Buchlin, E.; Solomon, J.; Soubrié, E.

2018-03-01

Long-period EUV pulsations, recently discovered to be common in active regions, are understood to be the coronal manifestation of thermal nonequilibrium (TNE). The active regions previously studied with EIT/Solar and Heliospheric Observatory and AIA/SDO indicated that long-period intensity pulsations are localized in only one or two loop bundles. The basic idea of this study is to understand why. For this purpose, we tested the response of different loop systems, using different magnetic configurations, to different stratifications and strengths of the heating. We present an extensive parameter-space study using 1D hydrodynamic simulations (1020 in total) and conclude that the occurrence of TNE requires specific combinations of parameters. Our study shows that the TNE cycles are confined to specific ranges in parameter space. This naturally explains why only some loops undergo constant periodic pulsations over several days: since the loop geometry and the heating properties generally vary from one loop to another in an active region, only the ones in which these parameters are compatible exhibit TNE cycles. Furthermore, these parameters (heating and geometry) are likely to vary significantly over the duration of a cycle, which potentially limits the possibilities of periodic behavior. This study also confirms that long-period intensity pulsations and coronal rain are two aspects of the same phenomenon: both phenomena can occur for similar heating conditions and can appear simultaneously in the simulations.

Digital subtraction angiography (DSA) of aortocoronary bypass grafts in the early postoperative phase with peripheral-venous contrast medium injection

International Nuclear Information System (INIS)

Tuengerthal, S.; Lang, J.; Donhoeffner, A.

1985-01-01

Using a fully digitalised subtraction unit, aortocoronary bypass grafts can be visualised in the early postoperative phase by means of peripheral venous contrast medium injection (57 out of a total of 60 cases). In more than one-half of the cases (31 out of a total of 60), it is possible to outline sharply the bypass grafts from the beginning to their entry into the bridged-over coronary artery, in such a manner that any loops, kinks, stenoses or reduced flow rates can be recognised. This examination is not considered to be an invasive one by the patient, and the cardiosurgeon can welcome it as a valuable additional means of controlling and assessing the results of surgery. (orig.) [de

MAP, MAC, and vortex-rings configurations in the Weinberg-Salam model

Science.gov (United States)

Teh, Rosy; Ng, Ban-Loong; Wong, Khai-Ming

2015-11-01

We report on the presence of new axially symmetric monopoles, antimonopoles and vortex-rings solutions of the SU(2)×U(1) Weinberg-Salam model of electromagnetic and weak interactions. When the ϕ-winding number n = 1, and 2, the configurations are monopole-antimonopole pair (MAP) and monopole-antimonopole chain (MAC) with poles of alternating sign magnetic charge arranged along the z-axis. Vortex-rings start to appear from the MAP and MAC configurations when the winding number n = 3. The MAP configurations possess zero net magnetic charge whereas the MAC configurations possess net magnetic charge of 4 πn / e. In the MAP configurations, the monopole-antimonopole pair is bounded by the Z0 field flux string and there is an electromagnetic current loop encircling it. The monopole and antimonopole possess magnetic charges ± 4πn/e sin2θW respectively. In the MAC configurations there is no string connecting the monopole and the adjacent antimonopole and they possess magnetic charges ± 4 πn/e respectively. The MAC configurations possess infinite total energy and zero magnetic dipole moment whereas the MAP configurations which are actually sphalerons possess finite total energy and magnetic dipole moment. The configurations were investigated for varying values of Higgs self-coupling constant 0 ≤ λ ≤ 40 at Weinberg angle θW = π/4.

Evaluation of early coronary graft patency after coronary artery bypass graft surgery using multislice computed tomography angiography

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Raissi Kamal

2009-12-01

Full Text Available Abstract Background Coronary artery bypass graft (CABG surgery is the standard of care in the treatment of advanced coronary artery disease, and its long-term results are affected by the failure of bypass grafts. The aim of the present study was to evaluate the early patency rate in coronary bypass grafts. Methods A total of 107 consecutive patients who underwent CABG were included in this study. Early graft patency was evaluated via computed tomography (CT angiography in the first week after surgery. Results There were a total of 366 grafts, comprised of 250 venous grafts and 116 arterial grafts. Multi-slice CT detected acute graft occlusions in 32 (8.7% of all the grafts, including 26 (10% of the 250 venous grafts and 6 (5% of the 116 arterial grafts. The patency rates obtained were 97.3% for the left internal mammary (IMA grafts, 50% for the radial artery grafts, and 50% for the right IMA grafts. Additionally, 107 (96.4% grafts to the left anterior descending artery (LAD were classified as patent, whereas 1 (30% of the 3 grafts in the left circumflex (LCX region and 1 (50% of the 2 grafts in the right coronary artery (RCA territory were found to be occluded. In the venous category, 8 (13.7% of the 58 grafts to LAD were found to be occluded. In the LCX region, 9 (8.5% of the 106 grafts were classified as occluded, while the remaining 97 (91.5% grafts were patent. The venous grafts to RCA were occluded in 9 (10.4% of the 86 grafts. Amongst the multiple preoperative, intraoperative, and postoperative factors, pump time was significantly longer in the patients with occluded grafts than in those with patent grafts (P = 0.04. Conclusion The IMA grafts had the highest early patency rate amongst the coronary bypass grafts. However, the other arterial grafts were associated with a high rate of acute occlusions.

Pilot-in-the-Loop Analysis of Propulsive-Only Flight Control Systems

Science.gov (United States)

Chou, Hwei-Lan; Biezad, Daniel J.

1996-01-01

Longitudinal control system architectures are presented which directly couple flight stick motions to throttle commands for a multi-engine aircraft. This coupling enables positive attitude control with complete failure of the flight control system. The architectures chosen vary from simple feedback gains to classical lead-lag compensators with and without prefilters. Each architecture is reviewed for its appropriateness for piloted flight. The control systems are then analyzed with pilot-in-the-loop metrics related to bandwidth required for landing. Results indicate that current and proposed bandwidth requirements should be modified for throttles only flight control. Pilot ratings consistently showed better ratings than predicted by analysis. Recommendations are made for more robust design and implementation. The use of Quantitative Feedback Theory for compensator design is discussed. Although simple and effective augmented control can be achieved in a wide variety of failed configurations, a few configuration characteristics are dominant for pilot-in-the-loop control. These characteristics will be tested in a simulator study involving failed flight controls for a multi-engine aircraft.

Pancreas grafts

International Nuclear Information System (INIS)

Hahn, D.; Buell, U.; Land, W.; Unertl, K.

1981-01-01

Perfusion studies with sup(99m)Tc-DTPA, which has hitherto been used routinely to investigate renal grafts, have also proved useful for monitoring the perfusion of pancreas grafts. A total perfusion failure is equally reliably demonstrable as in renal grafts. Quantitatively smaller perfusion alterations can be demonstrated by monitoring the course. It seems possible to differentiate the salivary edema of a rejection reaction, well known from animal experiments, with the help of other paramters (e.g. creatinine). Further clinical studies are however necessary to confirm these results. (orig.) [de

Preliminary approach of the MELiSSA loop energy balance

Science.gov (United States)

Poulet, Lucie; Lamaze, Brigitte; Lebrun, Jean

Long duration missions, such as the establishment of permanent bases on the lunar surface or the travel to Mars, require a huge amount of life support consumables (e.g. food, water and oxygen). Current rockets are at the moment unable to launch such a mass from Earth. Consequently Regenerative Life Support Systems are necessary to sustain long-term manned space mission to increase recycling rates and so reduce the launched mass. Thus the European and Canadian research has been concentrating on the MELiSSA (Micro-Ecological Life Support System Alternative) project over the last 20 years. MELiSSA is an Environmental Controlled Life Support System (ECLSS), i.e. a closed regenerative loop inspired of a lake ecosystem. Using light as a source of energy, MELiSSA's goal is the recovery of food, water and oxygen from CO2 and organic wastes, using microorganisms and higher plants. The architecture of a ECLSS depends widely on the mission scenario. To compare several ECLSS architectures and in order to be able to evaluate them, ESA is developing a multi criteria evaluation tool: ALISSE (Advanced LIfe Support System Evaluator). One of these criteria is the energy needed to operate the ECLSS. Unlike other criteria like the physical mass, the energy criterion has not been investigated yet and needs hence a detailed analysis. It will consequently be the focus of this study. The main objective of the work presented here is to develop a dynamic tool able to estimate the energy balance for several configurations of the MELiSSA loop. The first step consists in establishing the energy balance using concrete figures from the MELiSSA Pilot Plant (MPP). This facility located at the Universitat Autonoma de Barcelona (UAB) is aimed at the ground demonstration of the MELiSSA loop. The MELiSSA loop is structured on several subsystems; each of them is characterized by supplies, exhausts and process reactions. For the purpose of this study (i.e. a generic tool) the solver EES (Engineering

Graft union formation in artichoke grafting onto wild and cultivated cardoon: an anatomical study.

Science.gov (United States)

Trinchera, Alessandra; Pandozy, Gianmarco; Rinaldi, Simona; Crinò, Paola; Temperini, Olindo; Rea, Elvira

2013-12-15

In order to develop a non-chemical method such as grafting effective against well-known artichoke soil borne diseases, an anatomical study of union formation in artichoke grafted onto selected wild and cultivated cardoon rootstocks, both resistant to Verticillium wilt, was performed. The cardoon accessions Belgio (cultivated cardoon) and Sardo (wild cardoon) were selected as rootstocks for grafting combinations with the artichoke cv. Romolo. Grafting experiments were carried out in the autumn and spring. The anatomical investigation of grafting union formation was conducted by scanning electron microscopy (SEM) on the grafting portions at the 3rd, 6th, 10th, 12th day after grafting. For the autumn experiment only, SEM analysis was also performed at 30 d after grafting. A high affinity between artichoke scion and cardoon rootstocks was observed, with some genotype differences in healing time between the two bionts. SEM images of scion/rootstock longitudinal sections revealed the appearance of many interconnecting structures between the two grafting components just 3d after grafting, followed by a vascular rearrangement and a callus development during graft union formation. De novo formation of many plasmodesmata between scion and rootstock confirmed their high compatibility, particularly in the globe artichoke/wild cardoon combination. Moreover, the duration of the early-stage grafting process could be influenced not only by the scion/rootstock compatibility, but also by the seasonal conditions, being favored by lower temperatures and a reduced light/dark photoperiod. Copyright © 2013 Elsevier GmbH. All rights reserved.

Bragg peak proton beam treatment of arteriovenous malformations of the brain

International Nuclear Information System (INIS)

Kjellberg, R.N.; Poletti, C.E.; Roberson, G.H.; Adams, R.D.

1978-01-01

This report describes 27 patients treated for arteriovenous malformations of the brain by the Bragg Peak proton beam method during the past 12 years. The authors are led to a measure of confidence that Bragg Peak proton therapy can be provided without lethal risk attributed to the procedure. In 21 patients no neurological change has occurred, two patients experienced neurological improvement and four have developed new neurological abnormalities considered complications of the therapy. (Auth.)

Carpal tunnel syndrome: a complication of arteriovenous fistula in hemodialysis patients.

Science.gov (United States)

Kumar, S.; Trivedi, H. L.; Smith, E. K.

1975-01-01

Symptoms of compression of the median nerve in the carpal tunnel developed in two patients in whom an arteriovenous fistula was created to alleviate chronic renal failure through hemodialysis. Anatomic changes in the wrist area due to the fistula are probably important in the development of this syndrome, and pre-existing uremic peripheral polyneuropathy may also be important in the early development of local symptoms of nerve damage. Images FIG. 1 PMID:1201544

A COMPARATIVE STUDY OF TYMPANOPLASTY USING SLICED CARTILAGE GRAFT VS. TEMPORALIS FASCIA GRAFT

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Rahul Ashok Telang

2018-02-01

Full Text Available BACKGROUND The objective of the study was to compare the hearing improvement after using sliced cartilage graft with that of temporalis fascia and to compare the graft take-up between the two graft materials. MATERIALS AND METHODS A prospective clinical study including 60 patients with chronic mucosal otitis media, who were selected randomly from the outpatient department, after obtaining their consent were divided into 2 groups of 30 each, and evaluated according the study protocol. Their pre-operative audiometry was recorded and both groups of patients underwent surgery with one of the graft materials- temporalis fascia or sliced tragal cartilage with a thickness of 0.5 mm. All patients were regularly followed up and post-operative audiometry was done at 3 months. The hearing improvement in the form of closure of air-bone-gap and graft take-up was analysed statistically. RESULTS The temporalis fascia graft group had a pre-operative ABG of 22.33 ± 6.24 dB and post-operative ABG of 12.33 ± 4.72 dB with hearing improvement of 10.00 dB. The sliced cartilage graft group had a pre-operative ABG of 20.77 ± 5.75 dB and postoperative ABG of 10.50 ± 4.46 dB with hearing improvement of 10.27 dB. In the temporalis fascia group, 28 (93.3% patients had good graft take-up and in the sliced cartilage group 29 (96.7% had good graft take-up. There was statistically significant hearing improvement in both of our study groups but there was no statistically significant difference between the two groups. There was no statistically significant difference in graft take-up also. CONCLUSION Sliced cartilage graft is a good auto-graft material in tympanoplasty, which can give good hearing improvement and has good graft take-up, which is comparable with that of temporalis fascia.

Pathogenesis of arteriovenous malformations in the absence of endoglin.

Science.gov (United States)

Mahmoud, Marwa; Allinson, Kathleen R; Zhai, Zhenhua; Oakenfull, Rachael; Ghandi, Pranita; Adams, Ralf H; Fruttiger, Marcus; Arthur, Helen M

2010-04-30

Arteriovenous malformations (AVMs) result in anomalous direct blood flow between arteries and veins, bypassing the normal capillary bed. Depending on size and location, AVMs may lead to severe clinical effects including systemic cyanosis (pulmonary AVMs), hemorrhagic stroke (cerebral AVMs) and high output cardiac failure (hepatic AVMs). The factors leading to AVM formation are poorly understood, but patients with the familial disease hereditary hemorrhagic telangiectasia (HHT) develop AVMs at high frequency. As most HHT patients have mutations in ENG (endoglin) or ACVRL1 (activin receptor-like kinase 1), a better understanding of the role of these genes in vascular development is likely to reveal the etiology of AVM formation. Using a mouse with a conditional mutation in the Eng gene, we investigated the sequence of abnormal cellular events occurring during development of an AVM. In the absence of endoglin, subcutaneous Matrigel implants in adult mice were populated by reduced numbers of new blood vessels compared with controls, and resulted in local venous enlargement (venomegaly). To investigate abnormal vascular responses in more detail, we turned to the more readily accessible vasculature of the neonatal retina. Endoglin-deficient retinas exhibited delayed remodeling of the capillary plexus, increased proliferation of endothelial cells and localized AVMs. Muscularization of the resulting arteriovenous shunts appeared to be a secondary response to increased blood flow. AVMs develop when an angiogenic stimulus is combined with endoglin depletion. Moreover, AVM formation appears to result from the combination of delayed vascular remodeling and an inappropriate endothelial cell proliferation response in the absence of endoglin.

Computerized transverse tomography of vascular lesions of the brain. I. Arteriovenous malformations

International Nuclear Information System (INIS)

Pressman, B.D.; Kirkwood, J.R.; Davis, D.O.

1975-01-01

Computerized transverse tomography (CTT) of the brain is a recently developed method which allows non-invasive roentgenologic evaluation of intracranial disease. Since its inception, major attention has been given to the diagnosis and evaluation of tumors, clots, infarcts, venticular size, and orbital lesions. The purpose of this report is to discuss the application of CTT to the diagnosis and evaluation of intracerebral arteriovenous malformations. (U.S.)

Advances in radiation grafting

International Nuclear Information System (INIS)

Hegazy, El-Sayed A.; AbdEl-Rehim, H.A.; Kamal, H.; Kandeel, K.A.

2001-01-01

Graft copolymerization is an attractive means for modifying base polymers because grafting frequently results in the superposition of properties relating to the backbone and pendent chains. Among the various methods for initiating the grafting reaction, ionizing radiation is the cleanest and most versatile method of grafting available. Ion-exchange membranes play an important role in modern technology, especially in separation and purification of materials. The search for improved membrane composition has considered almost every available polymeric material because of its great practical importance. Grafting of polymers with a mixture of monomers is important since different types of chains containing different functional groups are included. A great deal is focused on the waste treatment of heavy and toxic metals from wastewater because of the severe problems of environmental pollution. Functionalized polymers suitable for metal adsorption with their reactive functional groups such as carboxylic and pyridine groups suitable for waste treatment were prepared by radiation grafting method. More reactive chelating groups were further introduced to the grafted copolymer through its functional groups by chemical treatments with suitable reagents. The advances of radiation grafting and possible uses are briefly discussed

Availability analysis of nuclear power plant system with the consideration of logical loop structures

International Nuclear Information System (INIS)

Matsuoka, Takeshi

2013-01-01

Nuclear power plants have logical loop structures in their system configuration. The typical example is a power source system, that is, a nuclear plant generates electricity and it is used for the operation of pumps in the plant. For the reliability or availability analysis of nuclear power plants, it is necessary to treat accurately logical loop structures. Authors have proposed an exact method for solving logical loop structure in reliability analysis, and generalized method has recently been presented. A nuclear power plant system is taken up and essential parts of logical loop structures are modeled into relatively simple form. The procedure to solve a loop structure is shown in which the proposed generalized method is applied, and availability of the system with loop structure is accurately solved. The analysis results indicate that reconsideration of present plant operating procedure should be made for the increase of safety of nuclear power plant in case of 'Loss of offsite power' incident. The analysis results also show an important role of loop structures for maintaining the overall system availability. The analysis procedure is also useful in effectively designing high reliable systems. (author)

Nucleation of dislocation loops during irradiation in binary FCC alloys with different alloy compositions

International Nuclear Information System (INIS)

Hashimoto, T.; Shigenaka, N.; Fuse, M.

1992-01-01

Dislocation loop nucleation is analyzed using a rate theory based model for face-centered cubic (fcc) binary alloys containing A- and B-atoms. In order to calculate the nucleation process in concentrated alloys, the model considers three types of interstitial dumbbells composed of A- and B-atoms, AA-, BB-, and AB-type dumbbells. Conversions between these interstitial dumbbells are newly introduced in the formulation in consideration of dumbbell configurations and movements. The model also includes reactions, such as point defect production by irradiation, mutual recombination of an interstitial and a vacancy, and dislocation loop nucleation and growth. Parameter values are chosen based on the atom size of the alloy component elements, and dislocation loop nucleation kinetics are investigated while varying alloy compositions. Two different types of kinetics are obtained in accordance with the dominant loop nucleus type. The migration energy difference of AA- and BB-type interstitial dumbbells is important in the determination of the dominant loop nucleus type. The present model predicts that the dislocation loop concentration decrease with increasing under sized atoms content, but defect production rate and temperature dependences of loop concentration are insensitive to alloy compositions. (author)

Vegetable Grafting: The Implications of a Growing Agronomic Imperative for Vegetable Fruit Quality and Nutritive Value

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Marios C. Kyriacou

2017-05-01

implications of grafting for the configuration of vegetable fruit physicochemical quality and nutritive value.

Loop Transfer Matrix and Loop Quantum Mechanics

International Nuclear Information System (INIS)

Savvidy, George K.

2000-01-01

The gonihedric model of random surfaces on a 3d Euclidean lattice has equivalent representation in terms of transfer matrix K(Q i ,Q f ), which describes the propagation of loops Q. We extend the previous construction of the loop transfer matrix to the case of nonzero self-intersection coupling constant κ. We introduce the loop generalization of Fourier transformation which allows to diagonalize transfer matrices, that depend on symmetric difference of loops only and express all eigenvalues of 3d loop transfer matrix through the correlation functions of the corresponding 2d statistical system. The loop Fourier transformation allows to carry out the analogy with quantum mechanics of point particles, to introduce conjugate loop momentum P and to define loop quantum mechanics. We also consider transfer matrix on 4d lattice which describes propagation of memebranes. This transfer matrix can also be diagonalized by using the generalized Fourier transformation, and all its eigenvalues are equal to the correlation functions of the corresponding 3d statistical system. In particular the free energy of the 4d membrane system is equal to the free energy of 3d gonihedric system of loops and is equal to the free energy of 2d Ising model. (author)

Fístula arteriovenosa pós-nefrolitotripsia percutânea Arteriovenous fistula after percutaneous nephrolithotomy

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Luis Alberto Batista Peres

2009-09-01

Full Text Available Fístula arteriovenosa (FAV é uma rara complicação pós-nefrolitotripsia percutânea (NLP. Apresentamos o caso de um paciente de 70 anos, sexo masculino, que apresentou sangramento maciço após NLP, tratado por angioembolização renal superseletiva com implante de stent. Após a embolização, houve resolução do sangramento. FAV é uma complicação incomum da NLP, que pode ser tratada com sucesso com angioembolização.Arteriovenous fistula (AVF is a rare complication of percutaneous nephrolithotomy (PNL. We report the case of a 70-year-old man, who had massive bleeding after PNL and underwent treatment with superselective renal angiographic embolization and stent implantation. Bleeding resolved after embolization. Arteriovenous fistula is an uncommon complication of PNL, which may be successfully treated with angiographic embolization.

Treat high cervical spinal arteriovenous malformation with Cyberknife radiosurgery

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Yu-Fen Huang

2014-01-01

Full Text Available This paper describes the use of CyberKnife radiosurgery in the treatment of accidentally found cervical spinal arteriovenous malformation (AVM. We present the case of a patient with cervical spinal AVM, who developed progressive neck pain, gait disturbance, urine and stool incontinence 2 weeks after the fell down accident. The patient underwent CyberKnife radiosurgery. After CyberKnife radiosurgery for 2 years, the patient′s neck pain diminished and was able to keep the walk without any assistance. The management of cervical spinal AVM varies. This patient demonstrated a successful treatment of cervical spinal AVM with CyberKnife radiosurgery.

The self-care with arteriovenous Fistula conducted by chronic renal failure.patients in the southern region of Mato Grosso.

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Camila Aoki Reinas

2012-01-01

Full Text Available The objective of the study is know the care with the arteriovenous fistula carried by the patient with chronic renal and the role of a nurse care to such. Is a descriptive, exploratory study of qualitative approach, developed with 20 patients in a dialysis clinic in Rondonópolis (MT, through individual interviews using a semi structured questionnaire. The analysis of the data was content analysis as categorical recommended by Bardin, resulting in two categories: self care with arteriovenous fistula and nurses in health education. In the category of self-care with the arteriovenous fistula, 70% received guidance about the care of the fistula with the nurse, the care most often mentioned was "no catch weight." However, when asked about the reason for the realization of such care, a large part could not explain. In the category of the nurse in health education, the nurse was quoted once as exclusively responsible for the guidelines on caring for the FAV. Considering the results, there was lack of information of these patients, regarding the reasons for the need to care of it, which is more worrying.

Construction of a humanized antibody to hepatitis B surface antigen by specificity-determining residues (SDR)-grafting and de-immunization.

Science.gov (United States)

Kim, Keun-Soo; Kim, Hyun-Jung; Han, Byung Woo; Myung, Pyung-Keun; Hong, Hyo Jeong

2010-05-28

We previously constructed a humanized antibody, HuS10, by grafting the complementarity-determining regions (CDRs) of a parental murine monoclonal antibody into the homologous human antibody sequences. This process is termed CDR grafting. Some residues that were thought to affect the CDR loops and stabilize the structure of the variable regions were retained in the framework region. HuS10 exhibited in vivo virus-neutralizing activity, but its murine content had the potential to elicit immune responses in patients. In this study, to minimize the immunogenic potential of HuS10, we replaced 17 mouse residues in HuS10 with the comparable human residues using specificity-determining residue (SDR)-grafting and de-immunization methods. The resultant humanized antibody, HzS-III, had the same affinity and epitope specificity as HuS10 and had reduced immunogenic potential, as assessed by T-cell epitope analysis. Thus, SDR grafting in combination with de-immunization may be a useful strategy for minimizing the immunogenicity of humanized antibodies. In addition, HzS-III may be a good candidate for immunoprophylaxis of HBV infection. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Extensive white matter changes after stereotactic radiosurgery for brain arteriovenous malformations: a prognostic sign for obliteration?

NARCIS (Netherlands)

van den Berg, R.; Buis, D. R.; Lagerwaard, F. J.; Lycklama a Nijeholt, G. J.; Vandertop, W. P.

2008-01-01

OBJECTIVE: Perinidal high-signal-intensity changes on T2-weighted magnetic resonance imaging can be seen surrounding radiosurgically treated brain arteriovenous malformations (AVM). Occasionally, these signal intensity changes develop far beyond the irradiated volume. A retrospective analysis of

Extensive White Matter Changes After Stereotactic Radiosurgery for Brain Arteriovenous Malformations: A Prognostic Sign for Obliteration?

NARCIS (Netherlands)

van den Berg, R.; Buis, D.R.; Lagerwaard, F.J.; Nijeholt, G.J.L.A.; Vandertop, W.P.

2008-01-01

OBJECTIVE: Perinidal high-signal-intensity changes on T2-weighted magnetic resonance imaging can be seen surrounding radiosurgically treated brain arteriovenous malformations (AVM). Occasionally, these signal intensity changes develop far beyond the irradiated volume. A retrospective analysis of

Modification of polyetherurethane for biomedical application by radiation-induced grafting. I. Grafting procedure, determination of mechanical properties, and chemical modification of grafted films

International Nuclear Information System (INIS)

Jansen, B.; Ellinghorst, G.

1985-01-01

Radiation grafting of monomers onto suitable trunk polymers is a useful tool for tailoring new polymers for special purposes. This technique has been used in the past for the development of biocompatible materials, e.g., by grafting hydrogels onto mechanically stable polymers. In this first part of our work, the radiation grafting of hydrophilic or reactive monomers onto a polyetherurethane film using the pre-swelling technique is described. Following this technique the trunk polymer was swollen in the monomer before irradiation. As monomers 2-hydroxyethyl methacrylate (HEMA), 2,3-epoxypropyl methacrylate (GMA), 2,3-dihydroxypropyl methacrylate (GOMA), and acrylamide (AAm) were used. The kinetics of the grafting reactions were examined, and the distribution of the graft component inside the trunk polymer was investigated by means of infrared (IR) spectroscopy. Surface-grafted as well as bulk- and surface-grafted products could be obtained. The mechanical behavior of the grafted films--especially in the water-swollen state--was examined and compared with that of the pure trunk polymer. In nearly all cases it was found that the tensile strength sigma B and the elongation at break epsilon R decreases as the grafting yield increases. Modification of GMA- and AAm-grafted films via chemical reactions was performed to create new functional groups of biomedical interest. In this manner a diol structure, a carboxylic acid structure, and a sulfonic acid group could be introduced in the grafted polymer. The water uptake of such modified films is increased markedly when compared with that of the unmodified samples

Dural arteriovenous fistula presenting with exophthalmos and seizures.

Science.gov (United States)

Feyissa, Anteneh M; Ponce, Lucido L; Patterson, Joel T; Von Ritschl, Rudiger H; Smith, Robert G

2014-03-15

Concomitant seizures and exophthalmos in the context of a temporal dural arteriovenous fistula (dAVF) has not been described before. Here, we report a 55-year-old-male who presented with an 8-month history of progressive painless exophthalmos of his left eye, conjunctival chemosis, reduced vision and new onset complex partial seizures. Cerebral angiography demonstrated Cognard Type IIa left cerebral dAVF fed by branches from the left occipital artery and an accessory meningeal artery, with drainage to the superior ophthalmic vein. Following surgical obliteration of dAVF feeding vessels, our patient had dramatic improvement in visual acuity, proptosis and chemosis along with cessation of clinical seizures. Published by Elsevier B.V.

Appraising the plasticity of the circle of Willis: a model of hemodynamic modulation in cerebral arteriovenous malformations.

Science.gov (United States)

Chuang, Yu-Ming; Guo, Wanyuo; Lin, Ching-Po

2010-01-01

Cerebral arteriovenous malformations (AVMs) harbor a network of abnormal vasculatures, namely the nidus between arterial and venous components. The pressure gradient between these two components results in abnormal high-velocity arteriovenous shunts flowing through the nidus and alternate intracranial hemodynamics. This study hypothesizes that the flow patterns of the circle of Willis (CoW) are modulated by the alternation of intracranial hemodynamics occurring in cerebral AVMs. The flow patterns of the CoW before and after AVMs had been corrected and the arteriovenous shunts closed by radiosurgery were assessed to validate the hypothesis. Fifty patients (32 men and 18 women; mean age 35.8 +/- 4.2, range 23-52 years) with cerebral AVMs previously treated by radiosurgery were retrospectively investigated. This investigation used magnetic resonance angiography, performed prior to and after AVM surgery, to assess the CoW flow patterns. The CoW flow patterns in nearly half of the subjects (20/50, 40%) altered after the AVMs had been corrected. The alterations included: (1) decreased size or ceased flow patterns in the CoW vascular segment: ipsilateral A1 (n = 1) of the anterior cerebral artery (ACA), ipsilateral posterior communicating artery (PCoA) segment (n = 7), contralateral PCoA collateral (n = 4), bilateral PCoA (n = 2); (2) increased size or opening of the previous 'hypoplastic' segment of CoW: ipsilateral A1 of ACA (n = 1), contralateral PCoA (n = 2), bilateral PCoA (n = 1), and (3) biphasic alteration of the CoW: ceased ipsilateral PCoA segment and opening ipsilateral A1 of the ACA (n = 1), ceased ipsilateral PCoA and opening contralateral P1 of the posterior cerebral artery (n = 1). The plasticity of the flow patterns in the CoW are modulated by intracranial hemodynamics as shown by the AVM model. The calibers of CoW arterial segments are not a static feature. Willisian collateralization with recruitment of the CoW segment may cease, or hypoplastic segments

Toward precision holography with supersymmetric Wilson loops

Energy Technology Data Exchange (ETDEWEB)

Faraggi, Alberto [Instituto de Física, Pontificia Universidad Católica de Chile,Casilla 306, Santiago (Chile); Zayas, Leopoldo A. Pando [The Abdus Salam International Centre for Theoretical Physics,Strada Costiera 11, 34014 Trieste (Italy); Michigan Center for Theoretical Physics, Department of Physics,University of Michigan, Ann Arbor, MI 48109 (United States); Silva, Guillermo A. [Instituto de Física de La Plata - CONICET & Departamento de Física - UNLP,C.C. 67, 1900 La Plata (Argentina); Trancanelli, Diego [Institute of Physics, University of São Paulo,05314-970 São Paulo (Brazil)

2016-04-11

We consider certain 1/4 BPS Wilson loop operators in SU(N)N=4 supersymmetric Yang-Mills theory, whose expectation value can be computed exactly via supersymmetric localization. Holographically, these operators are mapped to fundamental strings in AdS{sub 5}×S{sup 5}. The string on-shell action reproduces the large N and large coupling limit of the gauge theory expectation value and, according to the AdS/CFT correspondence, there should also be a precise match between subleading corrections to these limits. We perform a test of such match at next-to-leading order in string theory, by deriving the spectrum of quantum fluctuations around the classical string solution and by computing the corresponding 1-loop effective action. We discuss in detail the supermultiplet structure of the fluctuations. To remove a possible source of ambiguity in the ghost zero mode measure, we compare the 1/4 BPS configuration with the 1/2 BPS one, dual to a circular Wilson loop. We find a discrepancy between the string theory result and the gauge theory prediction, confirming a previous result in the literature. We are able to track the modes from which this discrepancy originates, as well as the modes that by themselves would give the expected result.

Self-corrective T-loop design for differential space closure.

Science.gov (United States)

Viecilli, Rodrigo F

2006-01-01

The current approach to measuring T-loop force systems in patients requiring differential anchorage does not consider active unit angulations and steps during space closure. The angulations and steps during movement introduced by rotation can considerably modify the force system acting on the teeth. In this study, geometric modifications were determined during controlled tipping of the 6 anterior teeth, where there was no movement of the posterior teeth, thus configuring a type A anchorage situation. An optimal beta-titanium alloy 0.017 x 0.025-in T-loop spring was designed by using a simulation performed with LOOP software (dHAL Orthodontic Software, Athens, Greece) to allow compensation for anterior unit-position effect on the final force system. The force systems produced by this T-loop spring with and without geometric correction of the brackets have significant differences that should be considered in the segmented arch approach to space closure. The effects of steps, angles, and vertical forces were combined to produce an ideal T-loop design that would provide a more determinate force system. The effects and force systems are estimates based on simplified locations of the centers of resistance, assuming relatively constant behavior of the centers of rotation. These simplifications might differ slightly from what happens in vivo. The finite element method or an accurate spring tester capable of reproducing the geometric corrections should be used to ensure a precise force system.

Posterior cranial fossa arteriovenous fistula with presenting as caroticocavernous fistula

Energy Technology Data Exchange (ETDEWEB)

Liu, H M; Shih, H C; Huang, Y C; Wang, Y H [Dept. of Medical Imaging, National Taiwan University Hospital, Taipei (Taiwan)

2001-05-01

We report cases of posterior cranial fossa arteriovenous fistula (AVF) with presenting with exophthalmos, chemosis and tinnitus in 26- and 66-year-old men. The final diagnoses was vertebral artery AVF and AVF of the marginal sinus, respectively. The dominant venous drainage was the cause of the unusual presentation: both drained from the jugular bulb or marginal sinus, via the inferior petrosal and cavernous sinuses and superior ophthalmic vein. We used endovascular techniques, with coils and liquid adhesives to occlude the fistulae, with resolution of the symptoms and signs. (orig.)

Posterior cranial fossa arteriovenous fistula with presenting as caroticocavernous fistula

International Nuclear Information System (INIS)

Liu, H.M.; Shih, H.C.; Huang, Y.C.; Wang, Y.H.

2001-01-01

We report cases of posterior cranial fossa arteriovenous fistula (AVF) with presenting with exophthalmos, chemosis and tinnitus in 26- and 66-year-old men. The final diagnoses was vertebral artery AVF and AVF of the marginal sinus, respectively. The dominant venous drainage was the cause of the unusual presentation: both drained from the jugular bulb or marginal sinus, via the inferior petrosal and cavernous sinuses and superior ophthalmic vein. We used endovascular techniques, with coils and liquid adhesives to occlude the fistulae, with resolution of the symptoms and signs. (orig.)

Ischemic stroke in combined cerebrovascular abnormalities - aneurysm of the right internal carotid artery and arteriovenous malformation temporo occipital in the right hemisphere

International Nuclear Information System (INIS)

Manolova, T.; Naydenov, K.; Manchev, I.; Manchev, L.

2016-01-01

A case of combined vascular abnormalities is presented- an aneurysm of the internal carotid artery and arterio-venous malformation temporooccipitally on the right, clinically presented by an ischemic brain stroke in the territory supplied by the right middle cerebral artery. Treatment included - hypo-tensive drugs, antiplatelet (antiaggregants) agents and vasodilators, which lead to significant improvement of the general and focal neurological symptoms. Neurosurgical intervention is been discussed, in order to remove the vascular malformation and to prevent future vascular events. Key words: Aneurysm. Arteriovenous Malformation. Ischemic Stroke

Particle exhaust scheme using an in-vessel cryocondensation pump in the advanced divertor configuration of the DIII-D tokamak

International Nuclear Information System (INIS)

Menon, M.M.; Mioduszewski, P.K.; Owen, L.W.; Anderson, P.M.; Baxi, C.B.; Langhorn, A.; Luxon, J.L.; Mahdavi, M.A.; Schaffer, M.J.; Schaubel, K.M.; "" class="author-name" title=" (General Atomics Co., San Diego, CA (United States))" data-affiliation=" (General Atomics Co., San Diego, CA (United States))" >Smith, J.P>

1992-01-01

In this paper, a particle exhaust scheme using a cryocondensation pump in the advanced divertor configuration of the DIII-D tokamak is described. In this configuration, the pump is located inside a baffle chamber within the tokamak, designed to receive particles reflected off the divertor strike region. A concentric coaxial loop with forced-convection flow of two-phase helium is selected as the cryocondensation surface. The pumping configuration is optimized by Monte Carlo techniques to provide maximum exhaust efficiency while minimizing the deleterious effects of impingement of energetic plasma particles on cryogenic surfaces. Heat loading contributions from various sources on the cryogenic surfaces are estimated, based on which the cryogenic surfaces are estimated, based on which the cryogenic flow loop for the pump is designed. The mechanical aspects of the pump, designed to meet the many challenging requirements of operating the cryopump internal to the tokamak vacuum and in close proximity with the high-temperature plasma, are also outlined

Ruptured cervical arteriovenous fistulas presenting with subarachnoid hemorrhage and quadriplegia: an uncommon case.

Science.gov (United States)

Liu, Chien-Liang; Su, Yung-Cheng; Chen, Chien-Chih; Chong, Chee-Fah; Wang, Tzong-Luen

2008-02-01

Nontraumatic subarachnoid hemorrhage is a neurologic emergency, and prompt treatment is necessary to avoid catastrophic result. We present a patient with subarachnoid hemorrhage caused by ruptured cervical intradural extramedullary arteriovenous fistulas, which rapidly progressed to quadriplegia. Because of the timely management, the patient had a good recovery. This is a rare but important case that emergency physicians should be aware of.

Splenic arteriovenous malformation manifested by thrombocytopenia in hereditary hemorrhagic telangiectasia: a case report

Energy Technology Data Exchange (ETDEWEB)

Kwon, Hee Jin; Choi, Jong Cheol; Oh, Jong Yeong; Cho, Jin Han; Kang, Myong Jin; Lee, Jin Hwa; Yoon, Seong Kuk; Nam, Kyeong Jin [College of Medicine, Dong-A University, Busan (Korea, Republic of)

2008-09-15

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant inherited disease characterized by epistaxis, telangiectases and visceral arteriovenous malformations (AVMs). The involvement of the gastrointestinal tract, liver, lung and cerebrum for HHT has been described, whereas little is known about AVMs of the spleen. We report here the radiological findings of a case of a splenic AVM manifested by thrombocytopenia in HHT.

Splenic arteriovenous malformation manifested by thrombocytopenia in hereditary hemorrhagic telangiectasia: a case report

International Nuclear Information System (INIS)

Kwon, Hee Jin; Choi, Jong Cheol; Oh, Jong Yeong; Cho, Jin Han; Kang, Myong Jin; Lee, Jin Hwa; Yoon, Seong Kuk; Nam, Kyeong Jin

2008-01-01

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant inherited disease characterized by epistaxis, telangiectases and visceral arteriovenous malformations (AVMs). The involvement of the gastrointestinal tract, liver, lung and cerebrum for HHT has been described, whereas little is known about AVMs of the spleen. We report here the radiological findings of a case of a splenic AVM manifested by thrombocytopenia in HHT

Hexagon functions and the three-loop remainder function

Energy Technology Data Exchange (ETDEWEB)

Dixon, Lance J.; Drummond, James M.; von Hippel, Matt; Pennington, Jeffrey

2013-12-01

We present the three-loop remainder function, which describes the scattering of six gluons in the maximally-helicity-violating configuration in planar NN = 4 super-Yang-Mills theory, as a function of the three dual conformal cross ratios. The result can be expressed in terms of multiple Goncharov polylogarithms. We also employ a more restricted class of hexagon functions which have the correct branch cuts and certain other restrictions on their symbols. We classify all the hexagon functions through transcendental weight five, using the coproduct for their Hopf algebra iteratively, which amounts to a set of first-order differential equations. The three-loop remainder function is a particular weight-six hexagon function, whose symbol was determined previously. The differential equations can be integrated numerically for generic values of the cross ratios, or analytically in certain kinematic limits, including the near-collinear and multi-Regge limits. These limits allow us to impose constraints from the operator product expansion and multi-Regge factorization directly at the function level, and thereby to fix uniquely a set of Riemann ζ valued constants that could not be fixed at the level of the symbol. The near-collinear limits agree precisely with recent predictions by Basso, Sever and Vieira based on integrability. The multi-Regge limits agree with the factorization formula of Fadin and Lipatov, and determine three constants entering the impact factor at this order. We plot the three-loop remainder function for various slices of the Euclidean region of positive cross ratios, and compare it to the two-loop one. For large ranges of the cross ratios, the ratio of the three-loop to the two-loop remainder function is relatively constant, and close to -7.

Determining the degree of grafting for poly (vinylidene fluoride) graft-copolymers using fluorine elemental analysis

International Nuclear Information System (INIS)

Yu Yang; Zhang Bowu; Yang Xuanxuan; Deng Bo; Li Linfan; Yu Ming; Li Jingye

2011-01-01

Acrylic acid (AAc) and styrene (St) were grafted onto poly (vinylidene fluoride) (PVDF) powder or membrane samples by pre-irradiation graft copolymerization. The grafted chains were proved by FT-IR spectroscopy analysis. The degree of grafting (DG) of the grafted PVDF was determined by fluorine elemental analysis (FEA) method, and was compared with the DGs determined by weighing method, acid-base back titration method and quantitative FT-IR method. The results show that the FEA method is accurate, convenient and universal, especially for the grafted polymer powders. (authors)

Bone grafts in dentistry

Directory of Open Access Journals (Sweden)

Prasanna Kumar

2013-01-01

Full Text Available Bone grafts are used as a filler and scaffold to facilitate bone formation and promote wound healing. These grafts are bioresorbable and have no antigen-antibody reaction. These bone grafts act as a mineral reservoir which induces new bone formation.

Penile Inversion Vaginoplasty with or without Additional Full-Thickness Skin Graft: To Graft or Not to Graft?

Science.gov (United States)

Buncamper, Marlon E; van der Sluis, Wouter B; de Vries, Max; Witte, Birgit I; Bouman, Mark-Bram; Mullender, Margriet G

2017-03-01

Penile inversion vaginoplasty is considered to be the gold standard for gender reassignment surgery in transgender women. The use of additional full-thickness skin graft as neovaginal lining is controversial. Some believe that having extra penile skin for the vulva gives better aesthetic results. Others believe that it gives inferior functional results because of insensitivity and skin graft contraction. Transgender women undergoing penile inversion vaginoplasty were studied prospectively. The option to add full-thickness skin graft is offered in patients where the penile skin length lies between 7 and 12 cm. Neovaginal depth was measured at surgery and during follow-up (3, 13, 26, and 52 weeks postoperatively). Satisfaction with the aesthetic result, neovaginal depth, and dilation regimen during follow-up were recorded. Satisfaction, sexual function, and genital self-image were assessed using questionnaires. A total of 100 patients were included (32 with and 68 without additional full-thickness skin graft). Patient-reported aesthetic outcome, overall satisfaction with the neovagina, sexual function, and genital self-image were not significantly associated with surgical technique. The mean intraoperative neovaginal depth was 13.8 ± 1.4 cm. After 1 year, this was 11.5 ± 2.5 cm. The largest decline (-15 percent) in depth is observed in the first 3 postoperative weeks (p skin graft use, in penile inversion vaginoplasty. The additional use of full-thickness skin graft does not influence neovaginal shrinkage, nor does it affect the patient- and physician-reported aesthetic or functional outcome. Therapeutic, IV.

Dislocation loops in ultra-high purity Fe(Cr) alloys after 7.2 MeV proton irradiation

Science.gov (United States)

Chen, J.; Duval, F.; Jung, P.; Schäublin, R.; Gao, N.; Barthe, M. F.

2018-05-01

Ultra-high purity Fe(Cr) alloys (from 0 wt% Cr to 14 wt% Cr) were 3D homogeneously irradiated by 0-7.2 MeV protons to 0.3 dpa at nominal temperatures from 270 °C to 500 °C. Microstructural changes were observed by transmission electron microscopy (TEM). The results showed that evolution of dislocation loops depends on the Cr content. Below 300 °C, large ½ a0 loops are dominating. Above 300 °C, a0 loops with a habit plane {100} appear. Loop sizes of both types are more or less the same. At temperatures from 310 °C to 400 °C, a0 loops form clusters with the same {100} habit plane as the one of the loops forming them. This indicates that loops of the same variant start gliding under mutual elastic interaction. At 500 °C, dislocation loops form disc shaped clusters about 1000 nm in diameter and sitting on {111} and/or {100} planes in the pure Fe samples. Based on these observations a quantitative analysis of the dislocation loops configurations and their temperature dependence is made, leading to an understanding of the basic mechanisms of formation of these loops.

A new design concept for knitted external vein-graft support mesh.

Science.gov (United States)

Singh, Charanpreet; Wang, Xungai

2015-08-01

Autologous vein-graft failure significantly limits the long-term efficacy of coronary artery bypass procedures. The major cause behind this complication is biomechanical mismatch between the vein and coronary artery. The implanted vein experiences a sudden increase (10-12 fold) in luminal pressures. The resulting vein over-distension or 'ballooning' initiates wall thickening phenomenon and ultimate occlusion. Therefore, a primary goal in improving the longevity of a coronary bypass procedure is to inhibit vein over-distension using mechanical constriction. The idea of using an external vein-graft support mesh has demonstrated sustained benefits and wide acceptance in experimental studies. Nitinol based knitted structures have offered more promising mechanical features than other mesh designs owing to their unique loosely looped construction. However, the conventional plain knit construction still exhibits limitations (radial compliance, deployment ease, flexibility, and bending stresses) which limit this design from proving its real clinical advantage. The new knitted mesh design presented in this study is based on the concept of composite knitting utilising high modulus (nitinol and polyester) and low modulus (polyurethane) material components. The experimental comparison of the new design with a plain knit design demonstrated significant improvement in biomechanical (compliance, flexibility, extensibility, viscoelasticity) and procedural (deployment limit) parameters. The results are indicative of the promising role of new mesh in restoring the lost compliance and pulsatility of vein-graft at high arterial pressures. This way it can assist in controlled vein-graft remodelling and stepwise restoration of vein mechanical homoeostasis. Also, improvement in deployment limit parameter offers more flexibility for a surgeon to use a wide range of vein diameters, which may otherwise be rendered unusable for a plain knit mesh. Copyright © 2015 Elsevier Ltd. All rights

Magnetocrystalline and configurational anisotropies in Fe nanostructures

International Nuclear Information System (INIS)

Vavassori, P.; Bisero, D.; Carace, F.; Liberati, M.; Di Bona, A.; Gazzadi, G.C.; Valeri, S.

2005-01-01

Arrays of single-crystal Fe micron and submicron squares and disks, have been fabricated using a focused ion beam apparatus from a film epitaxially grown on MgO. The hysteresis loops of the patterned areas differ from those of the continuous film as a consequence of the different reversal determined by the lateral confinement of the Fe film. By means of modulated field magneto-optical anisometry measurements we studied the symmetry and the strength of the overall anisotropy. For the smaller square elements we observed a higher-order term in the overall anisotropy with eightfold symmetry arising from the configurational contribution

Occupational therapy for patients with an arterio-venous fistula

Directory of Open Access Journals (Sweden)

Iustinian BENGULESCU

2017-03-01

Full Text Available End stage renal disease (ESRD represents a chronic medical condition that has become a public health problem and requires substantial funding. The number of patients with ESRD is rapidly increasing. From the moment that ESRD is diagnosed, the natural evolution of this pathology is towards mandatory dialysis, in absence of a renal transplant procedure. In order to perform hemodialysis, a vascular access site must be created and maintained functional. A proper vascular access site allows an adequate blood flow through the dialysis machine, in order to obtain the required results. The arterio-venous fistula represents the number one recommended vascular access site procedure. Establishing and maintaining a vascular access represents one of the biggest problems in hemodialysis. The arterio-venous fistula thus becomes the patient’s lifeline. Maintaining a good quality vascular access site is a demanding process and requires cooperation between both the patient and the health care providers. For ESRD patients there is a constant concern regarding the patency of their vascular access. The aim of this paper is to present the postoperative measures that ESRD patients should provide in order to preserve their vascular access. Also, we want to present the main signs of an early complication that patients should recognize and therefore immediately present themselves to the physician. By establishing this type of cooperation and trust between the patient and the medical staff we will be able to reduce the number of surgical procedures required for the creation and maintenance of the vascular access. Our final thought remains that a well-informed patient has better chances of prolonging his “lifeline”.

Complex arteriovenous malformation - a case report

International Nuclear Information System (INIS)

Sirakov, S.; Penkov, M.; Marinov, M.; Kamenov, B.

2014-01-01

AVMs are composed of a network of channels interposed between feeding arteries and draining veins, without any direct shunt. Two different anatomic types of nidus may be more or less differentiated: The most frequent clinical presentations of brain AVMs are hemorrhage, seizure, chronic headache, and focal deficits not related to hemorrhage. We show a case of 27 years old female came to the hospital in heavy condition with subarachnoid hemorrhage Fisher 4. She had a history of 4 surgical operation of brain AVM in the last 10 years, without significant reduction of the malformation. After discussion of multidisciplinary team, of neuroradiologist and neurosurgeon was decided to be perform endovascular embolization, because of the better outcome for the patient. We performed endovascular treatment of the AVM with achieving subtotal embolization of malformation (90%). The patient recovery completely after 22 days and went home. For the next 18 months follow up there is no data of accidents for the patient. Key words: Arteriovenous Malformation. Subarachnoid hemorrhage. Endovascular treatment. Embolization

Design and analysis of heat exchanger networks for integrated Ca-looping systems

International Nuclear Information System (INIS)

Lara, Yolanda; Lisbona, Pilar; Martínez, Ana; Romeo, Luis M.

2013-01-01

Highlights: • Heat integration is essential to minimize energy penalties in calcium looping cycles. • A design and analysis of four heat exchanger networks is stated. • New design with higher power, lower costs and lower destroyed exergy than base case. - Abstract: One of the main challenges of carbon capture and storage technologies deals with the energy penalty associated with CO 2 separation and compression processes. Thus, heat integration plays an essential role in the improvement of these systems’ efficiencies. CO 2 capture systems based on Ca-looping process present a great potential for residual heat integration with a new supercritical power plant. The pinch methodology is applied in this study to define the minimum energy requirements of the process and to design four configurations for the required heat exchanger network. The Second Law of Thermodynamics represents a powerful tool for reducing the energy demand since identifying the exergy losses of the system serves to allocate inefficiencies. In parallel, an economic analysis is required to asses the cost reduction achieved by each configuration. This work presents a combination of pinch methodology with economic and exergetic analyses to select the more appropriate configuration of heat exchanger network. The lower costs and minor destroyed exergy obtained for the best proposed network result in a of 0.91% global energy efficiency increase

Wilson loop, Regge trajectory and hadron masses in a Yang-Mills theory from semiclassical strings

International Nuclear Information System (INIS)

Bigazzi, F.; Cotrone, A.L.; Martucci, L.; Pando Zayas, L.A.

2004-07-01

We compute the one-loop string corrections to the Wilson loop, glueball Regge trajectory and stringy hadron masses in the Witten model of non supersymmetric, large-N Yang-Mills theory. The classical string configurations corresponding to the above field theory objects are respectively: open straight strings, folded closed spinning strings, and strings orbiting in the internal part of the supergravity background. For the rectangular Wilson loop we show that besides the standard Luscher term, string corrections provide a rescaling of the field theory string tension. The one-loop corrections to the linear glueball Regge trajectories render them nonlinear with a positive intercept, as in the experimental soft Pomeron trajectory. Strings orbiting in the internal space predict a spectrum of hadronic-like states charged under global flavor symmetries which falls in the same universality class of other confining models. (author)

Double row loop-coil configuration for high-speed electrodynamic maglev suspension, guidance, propulsion and guideway directional switching

Science.gov (United States)

He, J.; Rote, D.M.

1996-05-21

A stabilization and propulsion system are disclosed comprising a series of loop-coils arranged in parallel rows wherein two rows combine to form one of two magnetic rails. Levitation and lateral stability are provided when the induced field in the magnetic rails interacts with the superconducting magnets mounted on the magnetic levitation vehicle. The loop-coils forming the magnetic rails have specified dimensions and a specified number of turns and by constructing differently these specifications, for one rail with respect to the other, the angle of tilt of the vehicle can be controlled during directional switching. Propulsion is provided by the interaction of a traveling magnetic wave associated with the coils forming the rails and the superconducting magnets on the vehicle. 12 figs.

Double row loop-coil configuration for high-speed electrodynamic maglev suspension, guidance, propulsion and guideway directional switching

Science.gov (United States)

He, Jianliang; Rote, Donald M.

1996-01-01

A stabilization and propulsion system comprising a series of loop-coils arranged in parallel rows wherein two rows combine to form one of two magnetic rails. Levitation and lateral stability are provided when the induced field in the magnetic rails interacts with the superconducting magnets mounted on the magnetic levitation vehicle. The loop-coils forming the magnetic rails have specified dimensions and a specified number of turns and by constructing differently these specifications, for one rail with respect to the other, the angle of tilt of the vehicle can be controlled during directional switching. Propulsion is provided by the interaction of a traveling magnetic wave associated with the coils forming the rails and the super conducting magnets on the vehicle.

A comparison of patency and interventions in thigh versus Hemodialysis Reliable Outflow grafts for chronic hemodialysis vascular access.

Science.gov (United States)

Brownie, Evan R; Kensinger, Clark D; Feurer, Irene D; Moore, Derek E; Shaffer, David

2016-11-01

With improvements in medical management and survival of patients with end-stage renal disease, maintaining durable vascular access is increasingly challenging. This study compared primary, assisted primary, and secondary patency, and procedure-specific complications, and evaluated whether the number of interventions to maintain or restore patency differed between prosthetic femoral-femoral looped inguinal access (thigh) grafts and Hemodialysis Reliable Outflow (HeRO; Hemosphere Inc, Minneapolis, Minn) grafts. A single-center, retrospective, intention-to-treat analysis was conducted of consecutive thigh and HeRO grafts placed between May 2004 and June 2015. Medical history, interventions to maintain or restore patency, and complications were abstracted from the electronic medical record. Data were analyzed using parametric and nonparametric statistical tests, Kaplan-Meier survival methods, and multivariable proportional hazards regression and logistic regression. Seventy-six (43 thigh, 33 HeRO) grafts were placed in 61 patients (54% male; age 53 [standard deviation, 13] years). Median follow-up time in the intention-to-treat analysis was 21.2 months (min, 0.0; max, 85.3 months) for thigh grafts and 6.7 months (min, 0.0; max, 56.3 months) for HeRO grafts (P = .02). The groups were comparable for sex, age, coronary artery disease, diabetes mellitus, peripheral vascular disease, and smoking history (all P ≥ .12). One thigh graft (2%) and five HeRO (15%) grafts failed primarily. In the intention-to-treat analysis, patency durations were significantly longer in the thigh grafts (all log-rank P ≤ .01). Point estimates of primary patency at 6 months, 1 year, and 3 years were 61%, 46%, and 4% for the thigh grafts and 25%, 15%, and 6% for the HeRO grafts. Point estimates of assisted primary patency at 6 months, 1 year, and 3 years were 75%, 66%, and 54% for the thigh grafts and 41%, 30%, and 10% for the HeRO grafts. Point estimates of secondary patency at 6�

Complications following linear accelerator based stereotactic radiation for cerebral arteriovenous malformations

DEFF Research Database (Denmark)

Skjøth-Rasmussen, Jane; Roed, Henrik; Ohlhues, Lars

2010-01-01

Primarily, gamma knife centers are predominant in publishing results on arteriovenous malformations (AVM) treatments including reports on risk profile. However, many patients are treated using a linear accelerator-most of these at smaller centers. Because this setting is different from a large...... gamma knife center, the risk profile at Linac departments could be different from the reported experience. Prescribed radiation doses are dependent on AVM volume. This study details results from a medium sized Linac department center focusing on risk profiles....

Stereotactic helium-ion radiosurgery for the treatment of intracranial arteriovenous malformations

International Nuclear Information System (INIS)

Fabrikant, J.I.; Levy, R.P.; Frankel, K.A.; Phillips, M.H.; Lyman, J.T.; Chuang, F.Y.S.; Steinberg, G.K.; Marks, M.P.

1989-12-01

One of the more challenging problems of vascular neurosurgery is the management of surgically-inaccessible arteriovenous malformations (AVMs) of the brain. At Lawrence Berkeley Laboratory, we have developed the method of stereotactic heavy-charged-particle (helium-ion) Bragg peak radiosurgery for treatment of inoperable intracranial AVMs in over 300 patients since 1980 [Fabrikant et al. 1989, Fabrikant et al. 1985, Levy et al. 1989]. This report describes patient selection, treatment method, clinical and neuroradiologic results and complications encountered. 4 refs

A grafting from approach to graft polystyrene chains at the surface of graphene nanolayers by RAFT polymerization: Various graft densities from hydroxyl groups

Energy Technology Data Exchange (ETDEWEB)

Roghani-Mamaqani, Hossein, E-mail: r.mamaghani@sut.ac.ir [Department of Polymer Engineering, Sahand University of Technology, PO Box 51335-1996, Tabriz (Iran, Islamic Republic of); Khezri, Khezrollah [School of Chemistry, University College of Science, University of Tehran, PO Box 14155-6455, Tehran (Iran, Islamic Republic of)

2016-01-01

Graphical abstract: (3-Aminopropyl) triethoxysilane was grafted at the surface of GO in low and high different graft densities to yield GOHAL and GOHAH, respectively. Subsequently, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (RA) was attached at the surface of GOHAL and GOHAH by an amidation reaction to yield GOHRL and GOHRH, respectively. Then, GOHRL and GOHRH were used in grafting from RAFT polymerization of styrene. - Highlights: • A RAFT agent grafted GO was used in grafting from RAFT polymerization of styrene. • The efficiency of RAFT agent attachment at the surface of GO is 41.12% for high density sample. • Polystyrene molecular weight is decreased by the addition of graphene content and also graft density of RAFT agent. - Abstract: (3-Aminopropyl) triethoxysilane was grafted at the surface of GO in low and high different graft densities to yield GOHAL and GOHAH, respectively. Subsequently, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (RA) was attached at the surface of GOHAL and GOHAH by an amidation reaction to yield GOHRL and GOHRH, respectively. Then, GOHRL and GOHRH were used in grafting from RAFT polymerization of styrene. Grafting of APTES and RA was approved by Fourier transform infrared spectroscopy, X-ray photo electron spectroscopy, and Raman spectroscopy. Expansion of graphene interlayer by oxidation and functionalization processes was evaluated by X-ray diffraction. Conversion values of styrene were calculated using gas chromatography. Molecular weight and PDI values of attached polystyrene (PS) chains were studied by size exclusion chromatography. Thermogravimetric analysis was also used to investigate the degradation temperatures, char contents, and graft contents of modifiers and PS chains. GOHRH and GOHRL reach to char content of 55.3 and 45.2% at 600 °C, which shows that weight ratio of modifier (APTES and RA moieties) is 15.3 and 5.2%, respectively. Scanning and transmission electron microscopies show that

Loop kinematics

International Nuclear Information System (INIS)

Migdal, A.A.

1982-01-01

Basic operators acting in the loop space are introduced. The topology of this space and properties of the Stokes type loop functionals are discussed. The parametrically invariant loop calculus developed here is used in the loop dynamics

Spontaneous regression of brain arteriovenous malformations--a clinical study and a systematic review of the literature

NARCIS (Netherlands)

Buis, Dennis R.; van den Berg, René; Lycklama, Geert; van der Worp, H. Bart; Dirven, Clemens M. F.; Vandertop, W. Peter

2004-01-01

OBJECTIVE AND IMPORTANCE: Complete spontaneous obliteration of a brain arteriovenous malformation (AVM) is a rare event, with 67 angiographically proven cases in the world literature. We present a new case and a systematic literature review to determine possible mechanisms underlying this unusual

arXiv Conformal anomaly of generalized form factors and finite loop integrals

CERN Document Server

Chicherin, Dmitry

2018-04-16

We reveal a new mechanism of conformal symmetry breaking at Born level. It occurs in generalized form factors with several local operators and an on-shell state of massless particles. The effect is due to hidden singularities on collinear configurations of the momenta. This conformal anomaly is different from the holomorphic anomaly of amplitudes. We present a number of examples in four and six dimensions. We find an application of the new conformal anomaly to finite loop momentum integrals with one or more massless legs. The collinear region around a massless leg creates a contact anomaly, made visible by the loop integration. The anomalous conformal Ward identity for an ℓ−loop integral is a 2nd-order differential equation whose right-hand side is an (ℓ − 1)−loop integral. It could serve as a new useful tool to find/test analytic expressions for conformal integrals. We illustrate this point with several examples of known integrals. We propose a new differential equation for the four-dimensional sca...

Current status of grafts and implants in rhinoplasty: Part II. Homologous grafts and allogenic implants.

Science.gov (United States)

Sajjadian, Ali; Naghshineh, Nima; Rubinstein, Roee

2010-03-01

After reading this article, the participant should be able to: 1. Understand the challenges in restoring volume and structural integrity in rhinoplasty. 2. Identify the appropriate uses of various homologous grafts and allogenic implants in reconstruction, including: (a) freeze-dried acellular allogenic cadaveric dermis grafts, (b) irradiated cartilage grafts, (c) hydroxyapatite mineral matrix, (d) silicone implants, (e) high-density polyethylene implants, (f) polytetrafluoroethylene implants, and (g) injectable filler materials. 3. Identify the advantages and disadvantages of each of these biomaterials. 4. Understand the specific techniques that may aid in the use these grafts or implants. This review specifically addresses the use of homologous grafts and allogenic implants in rhinoplasty. It is important to stress that autologous materials remain the preferred graft material for use in rhinoplasty, owing to their high biocompatibility and low risk of infection and extrusion. However, concerns of donor-site morbidity, graft availability, and graft resorption have motivated the development and use of homologous and allogenic implants.

Vein grafting in fingertip replantations.

Science.gov (United States)

Yan, Hede; Jackson, William D; Songcharoen, Somjade; Akdemir, Ovunc; Li, Zhijie; Chen, Xinglong; Jiang, Liangfu; Gao, Weiyang

2009-01-01

In this retrospective study, the survival rates of fingertip replantation with and without vein grafting were evaluated along with their postoperative functional and cosmetic results. One hundred twenty-one-fingertip amputations were performed in 103 patients between September 2002 and July 2007. Thirty-four amputated fingertips were replanted without vein grafting, while 87 amputated fingertips were replanted with vein grafting for arterial and/or venous repairs. The overall survival rates of the replantations with and without vein grafting were 90% (78/87) and 85% (29/34), respectively. The survival rates were 88% (36/41) with venous repair, 93% (25/27) with arterial repair, and 89% (17/19) with both. Nineteen patients without vein grafting and 48 patients with vein grafting had a follow-up period of more than one year. Good cosmetic and functional outcomes were observed in both groups of patients. The results show that vein grafting is a reliable technique in fingertip replantations, showing no significant difference (P > 0.05) in survival between those with and without vein grafting. Furthermore, no significant difference (P > 0.05) in survival was found between cases with vein grafts for arterial and/or venous repairs. In fingertip replantations with vein grafting, favorable functional and esthetic results can be achieved without sacrificing replantation survival. (c) 2009 Wiley-Liss, Inc.

The Analysis of Loop Seal Purge Time for the KHNP Pressurizer Safety Valve Test Facility Using the GOTHIC Code

Energy Technology Data Exchange (ETDEWEB)

Kim, Young Ae; Kim, Chang Hyun; Kweon, Gab Joo; Park, Jong Woon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

2007-10-15

The pressurizer safety valves (PSV) in Pressurized Water Reactors are required to provide the overpressure protection for the Reactor Coolant System (RCS) during the overpressure transients. Korea Hydro and Nuclear Power Company (KHNP) plans to build the PSV test facility for the purpose of providing the PSV pop-up characteristics and the loop seal dynamics for the new safety analysis. When the pressurizer safety valve is mounted in a loop seal configuration, the valve must initially pass the loop seal water prior to popping open on steam. The loop seal in the upstream of PSV prevents leakage of hydrogen gas or steam through the safety valve seat. This paper studies on the loop seal clearing dynamics using GOTHIC-7.2a code to verify the effects of loop seal purge time on the reactor coolant system overpressure.

The causes and the nursing interventions of the complications due to repeated embolization therapy for huge cerebral arteriovenous malformations

International Nuclear Information System (INIS)

Sun Lingfang; Sun Ge

2010-01-01

Objective: To investigate the causes of the complications occurred after repeated embolization therapy for huge cerebral arteriovenous malformations and to discuss their nursing interventions. Methods: A total of 54 embolization procedures were performed in 17 patients with huge cerebral arteriovenous malformations. The clinical data were retrospectively analyzed. The causes of complications were carefully examined and the preventive measures were discussed. The prompt and necessary nursing interventions were formulated in order to prevent the complications or serious consequences. Results: Among the total 17 patients, one patient gave up the treatment because of the cerebral hemorrhage which occurred two months after receiving 3 times of embolization therapy. One patient experienced cerebral vascular spasm during the procedure, which was relieved after antispasmodic medication and no neurological deficit was left behind. Two patients developed transient dizziness and headache, which were alleviated spontaneously. One patient presented with nervousness, fear and irritability, which made him hard to cooperate with the operation and the basis intravenous anesthesia was employed. No complications occurred in the remaining cases. Conclusion: The predictive nursing interventions for the prevention of complications are very important for obtaining a successful repeated embolization therapy for huge cerebral arteriovenous malformations, which will ensure that the patients can get the best treatment and the complications can be avoided. (authors)

Proliferation of sharp kinks on cosmic (super)string loops with junctions

International Nuclear Information System (INIS)

Binetruy, P.; Bohe, A.; Hertog, T.; Steer, D. A.

2010-01-01

Motivated by their effect on the gravitational wave signal emitted by cosmic strings, we study the dynamics of kinks on strings of different tensions meeting at junctions. The propagation of a kink through a Y junction leads to the formation of three 'daughter' kinks. Assuming a uniform distribution of the incoming wave vectors at the junction, we find there is a significant region of configuration space in which the sharpness of at least one of the daughter kinks is enhanced relative to the sharpness of the initial kink. For closed loops with junctions we show this leads to an exponential growth in time of very sharp kinks. Using numerical simulations of realistic, evolving cosmic string loops with junctions to calculate the distribution of kink amplitudes as a function of time, we show that loops of this kind typically develop several orders of magnitude of very sharp kinks before the two junctions collide. This collision, or other effects such as gravitational backreaction, may end the proliferation.

Evaluation of CT virtual intravascular endoscopy in fenestrated stent grafts: a preliminary study

Energy Technology Data Exchange (ETDEWEB)

Sun, Z. [Dept. of Imaging and Applied Physics, Curtin Univ. of Tech., Perth, WA (Australia); Allen, Y.; Fitzsimmons, B.; Hartely, D. [Cook R and D, WA (Australia); Lawrence-Brown, M. [Dept. of Public Health, Curtin Univ. of Tech., Perth, WA (Australia)

2007-06-15

We aim in this study to investigate the potential value of CT virtual intravascular endoscopy in patients diagnosed with abdominal aortic aneurysms undergoing fenestrated stent grafts. Both pre-and post-fenestration (within 3 months of implantation) multislice CT data were collected in eight patients and used for generation of virtual endoscopy images in our preliminary study. Variable fenestrations were deployed in 25 aortic branches with scallop fenestration implanted in six aortic ostia, large fenestration in four aortic ostia and small fenestration in 15 renal ostia, respectively. Measurements of the aortic ostia diameters both pre- and post-fenestration were successfully performed with virtual intravascular endoscopy visualization, and endovascular stents as well as their relationship to the aortic ostia were clearly demonstrated. Our results showed that there was no significant change of diameter of the aortic ostia following fenestrated stem grafts. Endovascular stents were clearly visualized on virtual endoscopy images, and no apparent deformity or malrotation was observed in this small group. Our preliminary study provides new insights into anatomic configuration/dimension of aortic ostia and endovascular stents, and virtual intravascular endoscopy could be a valuable technique to follow-up patients treated with fenestrated stent grafts. (orig.)

Evaluation of CT virtual intravascular endoscopy in fenestrated stent grafts: a preliminary study

International Nuclear Information System (INIS)

Sun, Z.; Allen, Y.; Fitzsimmons, B.; Hartely, D.; Lawrence-Brown, M.

2007-01-01

We aim in this study to investigate the potential value of CT virtual intravascular endoscopy in patients diagnosed with abdominal aortic aneurysms undergoing fenestrated stent grafts. Both pre-and post-fenestration (within 3 months of implantation) multislice CT data were collected in eight patients and used for generation of virtual endoscopy images in our preliminary study. Variable fenestrations were deployed in 25 aortic branches with scallop fenestration implanted in six aortic ostia, large fenestration in four aortic ostia and small fenestration in 15 renal ostia, respectively. Measurements of the aortic ostia diameters both pre- and post-fenestration were successfully performed with virtual intravascular endoscopy visualization, and endovascular stents as well as their relationship to the aortic ostia were clearly demonstrated. Our results showed that there was no significant change of diameter of the aortic ostia following fenestrated stem grafts. Endovascular stents were clearly visualized on virtual endoscopy images, and no apparent deformity or malrotation was observed in this small group. Our preliminary study provides new insights into anatomic configuration/dimension of aortic ostia and endovascular stents, and virtual intravascular endoscopy could be a valuable technique to follow-up patients treated with fenestrated stent grafts. (orig.)

[A case of anterior tibial arteriovenous fistula after closed fracture of the leg].

Science.gov (United States)

Touzard, R C

1975-01-01

This case permits one to emphasize the great rareness of arteriovenous fistula after closed fractures of the shaft of the tibia. Fistulas in this anterior tibial position are remarkably latent, cause no symptoms below the fistula nor symptoms of heart failure. Treatment by several ligatures, permitted this patient to return to work 15 days after operation without any further treatment. The patient no longer has any symptoms.

NONLINEAR FORCE-FREE MAGNETIC FIELD FITTING TO CORONAL LOOPS WITH AND WITHOUT STEREOSCOPY

International Nuclear Information System (INIS)

Aschwanden, Markus J.

2013-01-01

We developed a new nonlinear force-free magnetic field (NLFFF) forward-fitting algorithm based on an analytical approximation of force-free and divergence-free NLFFF solutions, which requires as input a line-of-sight magnetogram and traced two-dimensional (2D) loop coordinates of coronal loops only, in contrast to stereoscopically triangulated three-dimensional loop coordinates used in previous studies. Test results of simulated magnetic configurations and from four active regions observed with STEREO demonstrate that NLFFF solutions can be fitted with equal accuracy with or without stereoscopy, which relinquishes the necessity of STEREO data for magnetic modeling of active regions (on the solar disk). The 2D loop tracing method achieves a 2D misalignment of μ 2 = 2.°7 ± 1.°3 between the model field lines and observed loops, and an accuracy of ≈1.0% for the magnetic energy or free magnetic energy ratio. The three times higher spatial resolution of TRACE or SDO/AIA (compared with STEREO) also yields a proportionally smaller misalignment angle between model fit and observations. Visual/manual loop tracings are found to produce more accurate magnetic model fits than automated tracing algorithms. The computation time of the new forward-fitting code amounts to a few minutes per active region.

A simple rescue maneuver for unfolding and centering a tightly rolled graft in Descemet membrane endothelial keratoplasty

Directory of Open Access Journals (Sweden)

Droutsas K

2014-10-01

Full Text Available Konstantinos Droutsas,1,2 Thomas Bertelmann,1 Frank M Schroeder,1 Dimitrios Papaconstantinou,2 Walter Sekundo1 1Department of Ophthalmology, Philipps University, Marburg, Germany; 2First Department of Ophthalmology, University of Athens, Medical School of Athens, Athens, Greece Abstract: A 74-year-old man underwent Descemet membrane endothelial keratoplasty (DMEK for endothelial decompensation due to Fuchs endothelial dystrophy. After descemetorhexis, the DMEK graft was inserted into the anterior chamber. However, unfolding of the graft was not possible as the graft was very tightly rolled together and the anterior chamber deep. After placing a 30G-cannula connected to an air-filled syringe inside the roll's lumen, a small air bubble was injected, which allowed the roll to open up, until it assumed a “taco” configuration around the bubble. Then, the graft was centered by pressing the posterior part of the roll against, and sweeping it over the iris. In the present case a “tight” DMEK roll was successfully unfolded by injection of a single air bubble into the roll’s lumen and centered by a “sweeping” the partialy unfolded graft over the iris. This technique allowed a controlled unfolding and centering of the DMEK graft with limited trauma to the donor endothelium and may be applied in cases where other less traumatic maneuvers are not successful. Keywords: Fuchs endothelial dystrophy, surgical technique, endothelial keratoplasty

Determination of the distribution of graft yields following a radiation-induced graft copolymerization

International Nuclear Information System (INIS)

Schipschack, K.; Wagner, H.; Sawtschenko, L.

1976-01-01

In the radiation-induced graft copolymerization on solid initial polymers a distribution of graft yields takes place along the cross-sections of samples. Methods for determining this distribution, which are described in the literature, are reviewed. In our own investigations boards made of ethylene-vinyl acetate copolymers and grafted with vinyl chloride were used. Distributions of the grafted component obtained by infrared analysis of microtome cuts parallel to the surface are partly rather inhomogeneous, and are interpreted as dependent on the experimental parameters. (author)

Study on grafting glycidyl methacrylate onto HDPE membranes by pre-irradiation graft copolymerization

International Nuclear Information System (INIS)

Tong Long; Zu Jianhua; Liu Xinwen; Sun Guisheng; Yu Chunhui

2006-01-01

Glycidyl methacrylate (GMA) was grafted onto HDPE membranes by pre-irradiation method with 1.8 MeV E-beam and a kind of membranes having reactive epoxy groups was successfully synthesized. Effects of monomer concentration, reaction temperature and time and irradiation dose on the grafting yield were studied. Composition, thermo-property and surface morphology of the grafted membranes were studied by FTIR, DSC and Tapping-mode AFM, respectively. The FTIR measurements proved the synthesized copolymer is HDPE-g-GMA. The DSC results indicated the grafted HDPE's melting temperature (T m ) and heat of fusion (ΔH f ( HDPE) ) which was reduced with increasing grafting yield. The AFM images indicated that surface of the HDPE-g-GMA membranes was rougher than the virgin HDPE. (authors)

Prevention of primary vascular graft infection with silver-coated polyester graft in a porcine model

DEFF Research Database (Denmark)

Gao, H; Sandermann, J; Prag, J

2010-01-01

To evaluate the efficacy of a silver-coated vascular polyester graft in the prevention of graft infection after inoculation with Staphylococcus aureus in a porcine model.......To evaluate the efficacy of a silver-coated vascular polyester graft in the prevention of graft infection after inoculation with Staphylococcus aureus in a porcine model....

An equation oriented approach to steady state flowsheeting of methanol synthesis loop

International Nuclear Information System (INIS)

Fathikalajahi, J.; Baniadam, M.; Rahimpour, M.R.

2008-01-01

An equation-oriented approach was developed for steady state flowsheeting of a commercial methanol plant. The loop consists of fixed bed reactor, flash separator, preheater, coolers, and compressor. For steady sate flowsheeting of the plant mathematical model of reactor and other units are needed. Reactor used in loop is a Lurgi type and its configuration is rather complex. Previously reactor and flash separator are modeled as two important units of plant. The model is based on mass and energy balances in each equipment and utilizing some auxiliary equations such as rate of reaction and thermodynamics model for activity coefficients of liquid. In order to validate the mathematical model for the synthesis loop, some simulation data were performed using operating conditions and characteristics of the commercial plant. The good agreement between the steady state simulation results and the plant data shows the validity of the model

Ischaemic strokes in patients with pulmonary arteriovenous malformations and hereditary hemorrhagic telangiectasia: associations with iron deficiency and platelets.

Directory of Open Access Journals (Sweden)

Claire L Shovlin

Full Text Available BACKGROUND: Pulmonary first pass filtration of particles marginally exceeding ∼7 µm (the size of a red blood cell is used routinely in diagnostics, and allows cellular aggregates forming or entering the circulation in the preceding cardiac cycle to lodge safely in pulmonary capillaries/arterioles. Pulmonary arteriovenous malformations compromise capillary bed filtration, and are commonly associated with ischaemic stroke. Cohorts with CT-scan evident malformations associated with the highest contrast echocardiographic shunt grades are known to be at higher stroke risk. Our goal was to identify within this broad grouping, which patients were at higher risk of stroke. METHODOLOGY: 497 consecutive patients with CT-proven pulmonary arteriovenous malformations due to hereditary haemorrhagic telangiectasia were studied. Relationships with radiologically-confirmed clinical ischaemic stroke were examined using logistic regression, receiver operating characteristic analyses, and platelet studies. PRINCIPAL FINDINGS: Sixty-one individuals (12.3% had acute, non-iatrogenic ischaemic clinical strokes at a median age of 52 (IQR 41-63 years. In crude and age-adjusted logistic regression, stroke risk was associated not with venous thromboemboli or conventional neurovascular risk factors, but with low serum iron (adjusted odds ratio 0.96 [95% confidence intervals 0.92, 1.00], and more weakly with low oxygen saturations reflecting a larger right-to-left shunt (adjusted OR 0.96 [0.92, 1.01]. For the same pulmonary arteriovenous malformations, the stroke risk would approximately double with serum iron 6 µmol/L compared to mid-normal range (7-27 µmol/L. Platelet studies confirmed overlooked data that iron deficiency is associated with exuberant platelet aggregation to serotonin (5HT, correcting following iron treatment. By MANOVA, adjusting for participant and 5HT, iron or ferritin explained 14% of the variance in log-transformed aggregation-rate (p = 0

Skin graft - slideshow

Science.gov (United States)

... this page: //medlineplus.gov/ency/presentations/100100.htm Skin graft - series—Normal anatomy To use the sharing features ... entire body, and acts as a protective barrier. Skin grafts may be recommended for: Extensive wounds Burns Specific ...

Lycopene and flesh colour differences in grafted and non-grafted watermelon

OpenAIRE

Fekete D.; Stéger-Máté M.; Bőhm V.; Balázs G.; Kappel N.

2015-01-01

The experiment was carried out in three regions in Hungary (Jászszentandrás, Cece, Újkígyós) in 2013 to determine the fruit quality of grafted watermelon (Citrullus lanatus Thunb.). The “RX 467” seedless watermelon variety was grafted on two commercial rootstocks “FR STRONG” [Lagenaria siceraria (Mol.) Standl.] and “RS 841” (Cucurbita maxima Duchesne × Cucurbita moschata Duchesne). The lycopene and flesh colours are important quality characteristics even of the selfrooted and grafted watermel...

Boosted Fast Flux Loop Alternative Cooling Assessment

Energy Technology Data Exchange (ETDEWEB)

Glen R. Longhurst; Donna Post Guillen; James R. Parry; Douglas L. Porter; Bruce W. Wallace

2007-08-01

The Gas Test Loop (GTL) Project was instituted to develop the means for conducting fast neutron irradiation tests in a domestic radiation facility. It made use of booster fuel to achieve the high neutron flux, a hafnium thermal neutron absorber to attain the high fast-to-thermal flux ratio, a mixed gas temperature control system for maintaining experiment temperatures, and a compressed gas cooling system to remove heat from the experiment capsules and the hafnium thermal neutron absorber. This GTL system was determined to provide a fast (E > 0.1 MeV) flux greater than 1.0E+15 n/cm2-s with a fast-to-thermal flux ratio in the vicinity of 40. However, the estimated system acquisition cost from earlier studies was deemed to be high. That cost was strongly influenced by the compressed gas cooling system for experiment heat removal. Designers were challenged to find a less expensive way to achieve the required cooling. This report documents the results of the investigation leading to an alternatively cooled configuration, referred to now as the Boosted Fast Flux Loop (BFFL). This configuration relies on a composite material comprised of hafnium aluminide (Al3Hf) in an aluminum matrix to transfer heat from the experiment to pressurized water cooling channels while at the same time providing absorption of thermal neutrons. Investigations into the performance this configuration might achieve showed that it should perform at least as well as its gas-cooled predecessor. Physics calculations indicated that the fast neutron flux averaged over the central 40 cm (16 inches) relative to ATR core mid-plane in irradiation spaces would be about 1.04E+15 n/cm2-s. The fast-to-thermal flux ratio would be in excess of 40. Further, the particular configuration of cooling channels was relatively unimportant compared with the total amount of water in the apparatus in determining performance. Thermal analyses conducted on a candidate configuration showed the design of the water coolant and

A new grafting technique for tympanoplasty: tympanoplasty with a boomerang-shaped chondroperichondrial graft (TwBSCPG).

Science.gov (United States)

Dündar, Rıza; Soy, Fatih Kemal; Kulduk, Erkan; Muluk, Nuray Bayar; Cingi, Cemal

2014-10-01

The aim of this study was to introduce a new grafting technique in tympanoplasty that involves use of a boomerang-shaped chondroperichondrial graft (BSCPG). The anatomical and functional results were evaluated. A new tympanoplasty with boomerang-shaped chondroperichondrial graft (TwBSCPG) technique was used in 99 chronic otitis media patients with central or marginal perforation of the tympanic membrane and a normal middle ear mucosa. All 99 patients received chondroperichondrial cartilage grafts with a boomerang-shaped cartilage island left at the anterior and inferior parts. Postoperative follow-ups were conducted at months 1, 6, and 12. Preoperative and postoperative audiological examinations were performed and air-bone gaps were calculated according to the pure-tone averages (PTAs) of the patients. In the preoperative period, most (83.8%) air-bone gaps were ≥ 16 dB; after operating using the TwBSCPG technique, the air-bone gaps decreased to 0-10 dB in most patients (77.8%). In the TwBSCPG patients, the mean preoperative air-bone gap was 22.02 ± 6.74 dB SPL. Postoperatively, the mean postoperative air-bone gap was 8.70 ± 5.74 dB SPL. The TwBSCPG technique therefore decreased the postoperative air-bone gap compared to that preoperatively (p = 0.000, z = -8.645). At the 1-month follow-up, there were six graft perforations and one graft retraction. At the 6-month follow-up, there were nine graft perforations and three graft retractions. At 12 months, there were seven graft perforations and four graft retractions. During the first year after the boomerang tympanoplasty surgery, graft lateralization was not detected in any patient. Retractions were grade 1 according to the Sade classification and were localized to the postero-superior quadrant of the tympanic membrane. The TwBSCPG technique has benefits with respect to postoperative anatomical and audiological results. It prevents perforation of the tympanic membrane at the anterior quadrant and avoids graft

Two-phase natural circulation experiments in a pressurized water loop with CANDU geometry

International Nuclear Information System (INIS)

Ardron, K.H.; Krishnan, V.S.; McGee, G.R.; Anderson, J.W.D.; Hawley, E.H.

1984-07-01

To provide information on two-phase natural circulation in a CANDU-type coolant circuit a series of tests has been performed in the RD-12 loop at the Whiteshell Nuclear Research Establishment. RD-12 is a 10-MPa pressurized-water loop containing two active boilers, two pumps, and two, or four, heated horizontal channels arranged in a symmetrical figure-of-eight configuration characteristic of the CANDU reactor primary heat-transport system. In the tests, single-phase natural circulation was established in the loop and void was introduced by controlled draining, with the surge tank (pressurizer) valved out of the system. The paper reviews the experimental results obtained and describes the evolution of natural circulation flow in particular cases as voidage is progressively increased. The stability behaviour is discussed briefly with reference to a simple stability model

Angiographic Evaluation of Carotid Artery Grafting with Prefabricated Small-Diameter, Small-Intestinal Submucosa Grafts in Sheep

International Nuclear Information System (INIS)

Pavcnik, Dusan; Obermiller, Josef; Uchida, Barry T.; Van Alstine, William; Edwards, James M.; Landry, Gregory J.; Kaufman, John A.; Keller, Frederick S.; Roesch, Josef

2009-01-01

The purpose of this study was to report the longitudinal angiographic evaluation of prefabricated lyophilized small-intestinal submucosa (SIS) grafts placed in ovine carotid arteries and to demonstrate a variety of complications that developed. A total of 24 grafts, 10 cm long and 6 mm in diameter, were placed surgically as interposition grafts. Graft patency at 1 week was evaluated by Doppler ultrasound, and angiography was used for follow-up at 1 month and at 3 to 4 months. A 90% patency rate was found at 1 week, 65% at 1 month, and 30% at 3 to 4 months. On the patent grafts, angiography demonstrated a variety of changes, such as anastomotic stenoses, graft diffuse dilations and dissections, and aneurysm formation. These findings have not been previously demonstrated angiographically by other investigators reporting results with small-diameter vessel grafts made from fresh small-intestinal submucosa (SIS). The complications found were partially related to the graft construction from four SIS layers. Detailed longitudinal angiographic study should become an essential part of any future evaluation of small-vessel SIS grafting.

Prediction of complications in Gamma Knife radiosurgery of arteriovenous malformations

International Nuclear Information System (INIS)

Lax, I.; Karlsson, B.

1996-01-01

The incidence of complications following radiosurgical treatment of arteriovenous malformations (AVM) is presented. A simple relationship exists between average dose and risk of complications, and on this basis a model is presented that gives a qualitatively correct description of this relationship. The parameters of the model have been determined using a clinical material of 862 AVM treatments to give a quantitativley correct description of the risk of complications. The dose-response curve is described by a double-exponential function. An accurate description of the dose-response curve at high dose levels is shown to be very important in radiosurgery. (orig.)

Management of intracranial arteriovenous malformations

International Nuclear Information System (INIS)

Miyamoto, Susumu; Takahashi, Jun C.

2008-01-01

Intracranial arteriovenous malformations (AVMs) are congenital lesions that can cause serious neurological deficits or even death. They can manifest as intracranial hemorrhage, epileptic seizure, or other symptoms such as headache or tinnitus. They are detected by computed tomography or magnetic resonance imaging. Recently there have been significant developments in the management of AVMs. In this paper, the authors represent an overview of the epidemiology of AVMs and the existing treatment strategies. AVMs are ideally excised by standard microsurgical techniques. The grading scale which was proposed by Spetzler and Martin is widely used to estimate the risk of direct surgery. Stereotactic radiosurgery such as that using a gamma knife is very useful for small lesions located in eloquent areas. Technological advances in endovascular surgery have provided new alternatives in the treatment of AVMs. Currently indications for embolization can be divided into presurgical embolization in large AVMs to occlude deep arterial feeding vessels and embolization before stereotactic radiosurgery to reduce the size of the nidus. Palliative embolization can be also applied for patients with large, inoperable AVMs who are suffering from progressive neurological deficits secondary to venous hypertension and/or arterial steal phenomenon. (author)

Management of intracranial arteriovenous malformations

Energy Technology Data Exchange (ETDEWEB)

Miyamoto, Susumu; Takahashi, Jun C [National Cardiovascular Center, Suita, Osaka (Japan)

2008-10-15

Intracranial arteriovenous malformations (AVMs) are congenital lesions that can cause serious neurological deficits or even death. They can manifest as intracranial hemorrhage, epileptic seizure, or other symptoms such as headache or tinnitus. They are detected by computed tomography or magnetic resonance imaging. Recently there have been significant developments in the management of AVMs. In this paper, the authors represent an overview of the epidemiology of AVMs and the existing treatment strategies. AVMs are ideally excised by standard microsurgical techniques. The grading scale which was proposed by Spetzler and Martin is widely used to estimate the risk of direct surgery. Stereotactic radiosurgery such as that using a gamma knife is very useful for small lesions located in eloquent areas. Technological advances in endovascular surgery have provided new alternatives in the treatment of AVMs. Currently indications for embolization can be divided into presurgical embolization in large AVMs to occlude deep arterial feeding vessels and embolization before stereotactic radiosurgery to reduce the size of the nidus. Palliative embolization can be also applied for patients with large, inoperable AVMs who are suffering from progressive neurological deficits secondary to venous hypertension and/or arterial steal phenomenon. (author)

Impact of bone graft harvesting techniques on bone formation and graft resorption

DEFF Research Database (Denmark)

Saulacic, Nikola; Bosshardt, Dieter D; Jensen, Simon S

2015-01-01

BACKGROUND: Harvesting techniques can affect cellular parameters of autogenous bone grafts in vitro. Whether these differences translate to in vivo bone formation, however, remains unknown. OBJECTIVE: The purpose of this study was to assess the impact of different harvesting techniques on bone fo......: Transplantation of autogenous bone particles harvested with four techniques in the present model resulted in moderate differences in terms of bone formation and graft resorption.......BACKGROUND: Harvesting techniques can affect cellular parameters of autogenous bone grafts in vitro. Whether these differences translate to in vivo bone formation, however, remains unknown. OBJECTIVE: The purpose of this study was to assess the impact of different harvesting techniques on bone...... formation and graft resorption in vivo. MATERIAL AND METHODS: Four harvesting techniques were used: (i) corticocancellous blocks particulated by a bone mill; (ii) bone scraper; (iii) piezosurgery; and (iv) bone slurry collected from a filter device upon drilling. The grafts were placed into bone defects...

Adolescent External Iliac Artery Trauma: Recurrent Aneurysmal Dilatation of an Iliofemoral Saphenous Vein Graft Treated by Stent-Grafting

International Nuclear Information System (INIS)

Lenton, James; Davies, John; Homer-Vanniasinkam, S.; McPherson, Simon

2008-01-01

An adolescent male sustained a severe penetrating injury to the external iliac artery. Emergency surgical revascularization was with a reversed long saphenous vein interposition graft. The primary graft and the subsequent revision graft both became aneurysmal. The second graft aneurysm was successfully excluded by endovascular stent-grafts with medium-term primary patency. A venous graft was used initially rather than a synthetic graft to reduce the risk of infection and the potential problems from future growth. Aneurysmal dilatation of venous grafts in children and adolescents is a rare but recognized complication. To the best of our knowledge, exclusion of these aneurysms with stent-grafts has not been previously reported in the adolescent population.

Eph-B4 regulates adaptive venous remodeling to improve arteriovenous fistula patency

OpenAIRE

Protack, Clinton D.; Foster, Trenton R.; Hashimoto, Takuya; Yamamoto, Kota; Lee, Monica Y.; Kraehling, Jan R.; Bai, Hualong; Hu, Haidi; Isaji, Toshihiko; Santana, Jeans M.; Wang, Mo; Sessa, William C.; Dardik, Alan

2017-01-01

Low rates of arteriovenous fistula (AVF) maturation prevent optimal fistula use for hemodialysis; however, the mechanism of venous remodeling in the fistula environment is not well understood. We hypothesized that the embryonic venous determinant Eph-B4 mediates AVF maturation. In human AVF and a mouse aortocaval fistula model, Eph-B4 protein expression increased in the fistula vein; expression of the arterial determinant Ephrin-B2 also increased. Stimulation of Eph-B-mediated signaling with ...

Compliance Study of Endovascular Stent Grafts Incorporated with Polyester and Polyurethane Graft Materials in both Stented and Unstented Zones

Directory of Open Access Journals (Sweden)

Ying Guan

2016-08-01

Full Text Available Compliance mismatch between stent graft and host artery may induce complications and blood flow disorders. However, few studies have been reported on stent graft compliance. This study aims to explore the deformation and compliance of stent graft in stented and unstented zones under three pressure ranges. Compliance of two stent grafts incorporated with polyurethane graft (nitinol-PU and polyester graft (nitinol-PET materials respectively were tested; the stents used in the two stent grafts were identical. For the circumferential deformation of the stent grafts under each pressure range, the nitinol-PET stent graft was uniform in both zones. The nitinol-PU stent graft was circumferentially uniform in the stented zone, however, it was nonuniform in the unstented zone. The compliance of the PU graft material was 15 times higher than that of the PET graft. No significant difference in compliance was observed between stented and unstented zones of the nitinol-PET stent graft regardless of the applied pressure range. However, for the nitinol-PU stent graft, compliance of the unstented PU region was approximately twice that of the stented region; thus, compliance along the length of the nitinol-PU stent graft was not constant and different from that of the nitinol-PET stent graft.

An Arteriovenous Fistula Between the Internal Mammary Artery and the Pulmonary Vein Following Blunt Chest Trauma

International Nuclear Information System (INIS)

Ito, T.; Sakamoto, Toshihisa; Norio, Hirofumi; Kaji, Tatsumi; Okada, Yoshiaki

2005-01-01

A 67-year-old man suffered a traffic accident and was transferred to an emergency hospital close to the scene. He was diagnosed to have bilateral pneumohemothorax with a lung contusion, an anterior fracture dislocation of the C6-vertebra and a cervical cord injury at the level of C7. On the 48th day, massive hemoptysis was suddenly recognized. He was transferred in a state of shock to our hospital to undergo hemostasis for the bleeding. On the day of admission, a selective arteriogram showed extravasation from the left bronchial artery, for which embolization was carried out using Gelfoam. In spite of this treatment, his hemoptysis continued. On the next day, a selective left internal mammary arteriogram showed an arteriovenous fistula between the left internal mammary artery and the left pulmonary vein without any apparent extravasation. The arteriovenous fistula was successfully embolized using platinum fiber coils. The patient no longer demonstrated any hemoptysis after embolization

Automatic definition of prescription isodose for stereotactic irradiations of arteriovenous malformations

International Nuclear Information System (INIS)

Dejean, C.; Lefkopoulos, D.; Foulquier, J.N.; Schlienger, M.; Touboul, E.

2001-01-01

To evaluate dosimetric consequences generated by the automatic definition based on lesion coverage of prescription isodose. A clinical series of 124 arteriovenous malformations was analysed. Plan quality was quantified by the standard deviation of the differential dose volume histogram calculated in the lesion. We define two quantitative protocols based on lesion coverage for the automatic definition of prescription isodose using a volumetric definition of coverage (90% of lesion volume), and an isodose-based definition proposed) by RTOG (prescription isodose equals minimum isodose in the lesion divided by 0.9). We have evaluated the plans obtained for these two protocols, calculating several dose-volume indices. These indices are presented as a function of dose-volume histogram standard deviation in order to quantify the consequences of their variations for this representative series of plans. The margin our team tolerates is such that the sum of under-dosed lesion and overdosed healthy tissues factors remains lower than one. Protocol based on volumetric coverage gives results situated within this margin. Protocol based on RTOG definition produces conformation indices that could be greater than 1. The absolute dose would be decided taking into account examined dose-volume indices and clinical data. A protocol for automatic definition of prescription isodose using volumetric lesion coverage seems to be more judiciously adapted to arteriovenous malformation conformal plans in stereotactic conditions because of variations observed in the overdosage of healthy tissues. (authors)

Two-loop polygon Wilson loops in N = 4 SYM

International Nuclear Information System (INIS)

Anastasiou, C.; Brandhuber, A.; Heslop, P.; Spence, B.; Travaglini, G.; Khoze, V.V.

2009-01-01

We compute for the first time the two-loop corrections to arbitrary n-gon lightlike Wilson loops in N = 4 supersymmetric Yang-Mills theory, using efficient numerical methods. The calculation is motivated by the remarkable agreement between the finite part of planar six-point MHV amplitudes and hexagon Wilson loops which has been observed at two loops. At n = 6 we confirm that the ABDK/BDS ansatz must be corrected by adding a remainder function, which depends only on conformally invariant ratios of kinematic variables. We numerically compute remainder functions for n = 7,8 and verify dual conformal invariance. Furthermore, we study simple and multiple collinear limits of the Wilson loop remainder functions and demonstrate that they have precisely the form required by the collinear factorisation of the corresponding two-loop n-point amplitudes. The number of distinct diagram topologies contributing to the n-gon Wilson loops does not increase with n, and there is a fixed number of 'master integrals', which we have computed. Thus we have essentially computed general polygon Wilson loops, and if the correspondence with amplitudes continues to hold, all planar n-point two-loop MHV amplitudes in the N = 4 theory.

Depth of the graft bed influences split-skin graft contraction.

NARCIS (Netherlands)

Mensik, I.; Lamme, E.N.; Brychta, P.

2003-01-01

Contraction of a split-thickness skin graft used for coverage of large defects remains a great problem in plastic, burn and reconstructive surgery. In this study we evaluated healing of split-thickness skin grafts transplanted in wounds on the subcutaneous fat and muscle fascia in pigs. Four young

Secondary necrosis: the radiosurgery in the cerebral arteriovenous malformations. CT and MR aspects

International Nuclear Information System (INIS)

Pina, J.I.; Medrano, J.; Benito, J.L. de; Sierra, R. la; Feijoo, R.; Villavieja, J.L.

1995-01-01

The Ct and MR findings are presented for two patients previously diagnosed as having cerebral arteriovenous malformations (AVM), treated by means of stereotaxic radiosurgery. The study of their course following corticosteroid therapy is also reported. The diagnosis was based on changes in the MR signal and density on CT and on their late onset, and was confirmed by puncture. The good clinical and radiological course is discussed. (Author) 10 refs

Bone scintigraphy in evaluating the viability of composite bone grafts revascularized by microvascular anastomoses, conventional autogenous bone grafts, and free non-revascularized periosteal grafts

International Nuclear Information System (INIS)

Berggren, A.; Weiland, A.J.; Ostrup, L.T.

1982-01-01

Researchers studied the value of bone scintigraphy in the assessment of anastomotic patency and bone-cell viability in free bone grafts revascularized by microvascular anastomoses in twenty-seven dogs. The dogs were divided into three different groups, and scintigraphy was carried out using technetium-labeled methylene diphosphonate in composite bone grafts revascularized by microvascular anastomoses, conventional autogenous bone grafts, and periosteal grafts placed in different recipient beds. The viability of the grafts were evaluated by histological examination and fluorescence microscopy after triple labeling with oxytetracycline on the first postoperative day, alizarin complexone on the fourth postoperative day, and DCAF on the eleventh postoperative day. A positive scintiscan within the first week following surgery indicated patent microvascular anastomoses, and histological study and fluorescence microscopy confirmed that bone throughout the graft was viable. A positive scintiscan one week after surgery or later does not necessarily indicate microvascular patency or bone-cell survival, because new bone formed by creeping substitution on the surface of a dead bone graft can result in this finding

OPEN-LOOP CONTROL OF A BIPOLAR STEPPER MOTORS USING THE SPECIALIZED INTEGRATED CIRCUITS

Directory of Open Access Journals (Sweden)

Gheorghe BALUTA

2004-12-01

Full Text Available This paper describes the open-loop control of a stepper motors. Bipolar stepper motors can be driven with an L297, an L298N bridge driver and very few external components. With an L298N this configuration drives motors with winding currents up to 2.5A. If very high powers are required an equivalent circuit made with discrete transistors replaces the bridge driver. Together these two chips form a complete microprocessor-to-stepper motor interface. The command signals for the controller L297 are generated through an IBM-PC486 interface. It was developed an open-loop command program written in BorlandC programming language.

Acute Tetraparesis with Respiratory Failure after Steroid Administration in a Patient with a Dural Arteriovenous Fistula at the Craniocervical Junction

Science.gov (United States)

Takahashi, Hisashi; Ueshima, Taiki; Goto, Daiki; Kimura, Tadashi; Yuki, Natsuko; Inoue, Yasuo; Yoshioka, Akira

2017-01-01

A 63-year-old man developed vomiting, paraparesis, dysuria, bulbar palsy, and orthostatic hypotension over a period of 5 months. Neuroradiological examinations showed a swollen lower brainstem with a dural arteriovenous fistula at the craniocervical junction (DAVF-CCJ). A steroid was administered intravenously in the hospital to relieve brainstem edema. A few hours later, however, the patient developed acute tetraparesis with respiratory failure. Recently, there have been several reports describing the acute worsening of paraparesis in patients with a spinal dural arteriovenous fistula after steroid treatment. In addition to these reports, the present case suggests the risk of administering steroids to patients with DAVF-CCJ, especially those with brainstem dysfunction. PMID:29225249

One loop tadpole in heterotic string field theory

Science.gov (United States)

Erler, Theodore; Konopka, Sebastian; Sachs, Ivo

2017-11-01

We compute the off-shell 1-loop tadpole amplitude in heterotic string field theory. With a special choice of cubic vertex, we show that this amplitude can be computed exactly. We obtain explicit and elementary expressions for the Feynman graph decomposition of the moduli space, the local coordinate map at the puncture as a function of the modulus, and the b-ghost insertions needed for the integration measure. Recently developed homotopy algebra methods provide a consistent configuration of picture changing operators. We discuss the consequences of spurious poles for the choice of picture changing operators.

Osseous scintigraphy and auxiliary graft

International Nuclear Information System (INIS)

Khelifa, F.; Siles, S.; Puech, B.

1992-01-01

The scintigraphy could be a good way to survey the osseous graft: three cases are studied in which were recognized the presence of a graft, surinfection, graft lysis, pseudo-arthrosis, algodystrophy. 8 refs., 5 figs

Similar Outcomes in Diabetes Patients After Coronary Artery Bypass Grafting With Single Internal Thoracic Artery Plus Radial Artery Grafting and Bilateral Internal Thoracic Artery Grafting.

Science.gov (United States)

Raza, Sajjad; Blackstone, Eugene H; Houghtaling, Penny L; Koprivanac, Marijan; Ravichandren, Kirthi; Javadikasgari, Hoda; Bakaeen, Faisal G; Svensson, Lars G; Sabik, Joseph F

2017-12-01

The purpose of this study was to determine in patients with diabetes mellitus whether single internal thoracic artery (SITA) plus radial artery (RA) grafting yields outcomes similar to those of bilateral internal thoracic artery (BITA) grafting. From January 1994 to January 2011, 1,325 diabetic patients underwent primary isolated coronary artery bypass graft surgery with either (1) SITA plus RA with or without saphenous vein (SV) grafts (n = 965) or (2) BITA with or without SV grafts (n = 360); an internal thoracic artery was used in all patients to graft the left anterior descending coronary artery. Endpoints were in-hospital outcomes and time-related mortality. Median follow-up was 7.4 years, with a total follow-up of 9,162 patient-years. Propensity score matching was performed to identify 282 well-matched pairs for adjusted comparisons. Unadjusted in-hospital mortality was 0.52% for SITA plus RA with or without SV grafts and 0.28% for BITA with or without SV grafts, and prevalence of deep sternal wound infection was 3.2% and 1.7%, respectively. Unadjusted survival at 1, 5, 10, and 14 years was 97%, 88%, 68%, and 51% for SITA plus RA with or without SV grafts, and 97%, 95%, 80%, and 66% for BITA with or without SV grafts, respectively. Among propensity-matched patients, in-hospital mortality (0.35% versus 0.35%) and prevalence of deep sternal wound infection (1.4% versus 1.4%) were similar (p > 0.9) in the two groups, as was 1-, 5-, 10-, and 14-year survival: 97%, 90%, 70%, and 58% for SITA plus RA with or without SV grafting versus 97%, 93%, 79%, and 64% for BITA with or without SV grafting, respectively (early p = 0.8, late p = 0.2). For diabetic patients, SITA plus RA with or without SV grafting and BITA with or without SV grafting yield similar in-hospital outcomes and long-term survival after coronary artery bypass graft surgery. Therefore, both SITA plus RA and BITA plus SV grafting should be considered for these patients. Copyright © 2017 The Society

Four-dimensional computed tomography angiographic evaluation of cranial dural arteriovenous fistula before and after embolization

International Nuclear Information System (INIS)

Tian, Bing; Xu, Bing; Lu, Jianping; Liu, Qi; Wang, Li; Wang, Minjie

2015-01-01

Highlights: • 4D CTA showed excellent agreement with DSA with regard to identification of feeding arteries and drainage veins. • The most important finding was 4D CTA in determining the impact of DAVF treatment with transarterial embolization. • 4D CTA provides images similar to those obtained with DSA both before and after treatment. - Abstract: Purpose: This study aimed to evaluate the usefulness of four-dimensional CTA before and after embolization treatment with ONYX-18 in eleven patients with cranial dural arteriovenous fistulas, and to compare the results with those of the reference standard DSA. Patients and Methods: Eleven patients with cranial dural arteriovenous fistulas detected on DSA underwent transarterial embolization with ONYX-18. Four-dimensional CTA was performed an average of 2 days before and 4 days after DSA. Four-dimensional CTA and DSA images were reviewed by two neuroradiologists for identification of feeding arteries and drainage veins and for determining treatment effects. Interobserver and intermodality agreement between four-dimensional CTA and DSA were assessed. Results: Forty-two feeding arteries were identified for 14 fistulas in the 11 patients. Of these, 36 (85.71%) were detected on four-dimensional CTA. After transarterial embolization, one patient got partly embolized, and the fistulas in the remaining 10 patients were completely occluded. The interobserver agreement for four-dimensional CTA and intermodality agreement between four-dimensional CTA and DSA were excellent (κ = 1) for shunt location, identification of drainage veins, and fistula occlusion after treatment. Conclusion: Four-dimensional CTA images are highly accurate when compared with DSA images both before and after transarterial embolization treatment. Four-dimensional CTA can be used for diagnosis as well as follow-up of cranial dural arteriovenous fistulas in clinical settings

A Rare Case of Jejunal Arterio-Venous Fistula: Treatment with Superselective Catheter Embolization with a Tracker-18 Catheter and Microcoils

International Nuclear Information System (INIS)

Sonnenschein, Martin J.; Anderson, Suzanne E.; Lourens, Steven; Triller, Juergen

2004-01-01

Arterio-venous fistulas may develop spontaneously, following trauma or infection, or be iatrogenic in nature. We present a rare case of a jejunal arterio- venous fistula in a 35-year-old man with a history of pancreatic head resection that had been performed two years previously because of chronic pancreatitis. The patient was admitted with acute upper abdominal pain, vomiting and an abdominal machinery-type bruit. The diagnosis of a jejunal arterio-venous fistula was established by MR imaging. Transfemoral angiography was performed to assess the possibility of catheter embolization. The angiographic study revealed a small aneurysm of the third jejunal artery, abnormal early filling of dilated jejunal veins and marked filling of the slightly dilated portal vein (13-14 mm). We considered the presence of segmental portal hypertension. The patient was treated with coil embolization in the same angiographic session. This case report demonstrates the importance of auscultation of the abdomen in the initial clinical examination. MR imaging and color Doppler ultrasound are excellent noninvasive tools in establishing the diagnosis. The role of interventional radiological techniques in the treatment of early portal hypertension secondary to jejunal arterio-venous fistula is discussed at a time when this condition is still asymptomatic. A review of the current literature is included

Alternative loop rings

CERN Document Server

Goodaire, EG; Polcino Milies, C

1996-01-01

For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

Hydrophilic/hydrophobic character of grafted cellulose

Energy Technology Data Exchange (ETDEWEB)

Takacs, E., E-mail: takacs@iki.kfki.h [Institute of Isotopes, Hungarian Academy of Sciences, Budapest (Hungary); Wojnarovits, L. [Institute of Isotopes, Hungarian Academy of Sciences, Budapest (Hungary); Borsa, J. [Budapest University of Technology and Economics (Hungary); Racz, I. [Bay Zoltan Institute for Materials Science and Technology, Budapest (Hungary)

2010-04-15

Vinyl monomers with long paraffin chains were grafted onto two kinds of cellulose (cotton and cotton linter) by direct irradiation grafting technique. The effect of dose, monomer structure and concentration, as well as homopolymer suppressor (styrene) concentration on the grafting yield was studied and the optimal grafting conditions were established. Grafting decreased the swelling of the samples in water and increased their polymer compatibility in polypropylene matrix.

Fístula axilo-cava para hemodiálise: relato de caso Axillary arteriovenous fistula for hemodialysis: case report

Directory of Open Access Journals (Sweden)

Yosio Nagato

2009-12-01

Full Text Available Na confecção de fístula arteriovenosa (FAV para hemodiálise, condutos venosos autógenos demonstram performance superior quando comparados com material protético em relação à perviedade primária ou secundária. A prótese de politetrafluoroetileno (PTFE é reservada para casos de falência de material autógeno e é geralmente utilizada em fístulas em membros superiores. Descrevemos o caso de uma paciente de 52 anos que, após falência de acessos para hemodiálise e impossibilidade de realização de diálise peritoneal em razão de peritonite bacteriana, foi submetida à confecção de FAV entre a artéria axilar direita e a veia cava inferior com prótese de PTFE de 6 mm. O acesso foi utilizado para hemodiálise 1 mês após sua criação e permanece pérvio após 24 meses. Até o momento, não houve complicações infecciosas, sinais de insuficiência cardíaca ou síndrome de roubo em membro superior direito.With regards to the creation of an arteriovenous fistula (AV fistula for hemodialysis, autogenous venous grafts clearly show high performance when compared with prosthetic material in terms of primary or secondary patency. Polytetrafluoroethylene (PTFE grafts for the reconstruction of AV fistulae must be restricted to cases of failure of the autogenous material, which is generally used in upper limb fistulae. We describe a case of a 52-year-old patient, who, after access failure for hemodialysis and the impossibility of performing peritoneal dialysis due to bacterial peritonitis, underwent the reconstruction of an AV fistula between the right axillary artery and the cava vein using a 6-mm PTFE prosthesis. One month after surgery, this AV fistula started to be used for hemodialysis. The AV fistula remains patent 24 months after its creation. No infectious complications, cardiac insufficiency symptoms, or steal syndromes of right upper limb were detected.

Loop containment (joint integrity) assessment Brayton Isotope Power System flight system

International Nuclear Information System (INIS)

1976-01-01

The Brayton Isotope Power System (BIPS) contains a large number of joints. Since the failure of a joint would result in loss of the working fluid and consequential failure of the BIPS, the integrity of the joints is of paramount importance. The reliability of the ERDA BIPS loop containment (joint integrity) is evaluated. The conceptual flight system as presently configured is depicted. A brief description of the flight system is given

Comparison of Acute Thrombogenicity for Magnesium versus Stainless Steel Stents in a Porcine Arteriovenous Shunt Model.

Science.gov (United States)

Lipinski, Michael J; Acampado, Eduardo; Cheng, Qi; Adams, Lila; Torii, Sho; Gai, Jiaxiang; Torguson, Rebecca; Hellinga, David G; Joner, Michael; Harder, Claus; Zumstein, Philine; Finn, Aloke V; Kolodgie, Frank D; Virmani, Renu; Waksman, Ron

2018-05-08

Aims The aetiology for reduced thrombogenicity of the Magmaris resorbable magnesium scaffold (RMS) when compared with the Absorb bioresorbable vascular scaffold remains unclear. We therefore investigated whether the Magmaris RMS has platelet-repelling properties by comparing its acute thrombogenicity with an equivalent stainless steel stent in an arteriovenous shunt model. Methods and Results An ex vivo porcine carotid jugular arteriovenous shunt was established and connected to Sylgard tubing containing the Magmaris RMS with sirolimus-eluting PLLA coating and an equivalent 316L stainless steel stent with sirolimus-eluting PLLA coating. Six shunts (2 shunt runs per pig) were run comparing the 2 scaffolds (n=9) in alternating order. Nested generalised linear mixed models were employed to compare variables between scaffold groups. Confocal fluorescent microscopy costaining CD61/CD42b demonstrated that the 316L equivalent stent had significantly greater platelet coverage of the total scaffold compared with Magmaris (5.8% vs. 2.8%, Rate ratio 2.21 [1.41, 3.47], p=0.012). Scanning electron microscopy demonstrated significantly greater thrombus deposition on the 316L equivalent stent as a percentage of the total scaffold compared with Magmaris (8.0% vs. 5.3%, p=0.009). Magmaris also had significantly less CD14 positive monocyte deposition and a trend toward less PM-1 positive neutrophil compared with the 316L equivalent stent. Conclusion Despite having identical scaffold characteristics regarding geometrical design, Magmaris had significantly less thrombogenicity and inflammatory cell deposition compared with the equivalent 316L stainless steel stent in a porcine arteriovenous shunt model. These data suggest resorbable magnesium scaffolds may have inherent properties that reduce adhesion of platelets and inflammatory cells.

Two-phase natural circulation experiments in a pressurized water loop with CANDU geometry

Energy Technology Data Exchange (ETDEWEB)

Ardron, K.H.; Krishnan, V.S.; McGee, G.R.; Anderson, J.W.D.; Hawley, E.H.

1984-07-01

A series of tests has been performed in the RD-12 loop, a 10-MPa pressurized-water loop containing two active boilers, two pumps, and two, or four, heated horizontal channels arranged in a symmetrical figure-of-eight configuration characteristic of the CANDU reactor primary heat-transport system. In the tests, single-phase natural circulation was established in the loop and void was introduced by controlled draining, with the surge tank (pressurizer) valved out of the system. Results indicate that a stable, two-phase, natural circulation flow can usually be established. However, as the void fraction in the loop is increased, large-amplitude flow oscillations can occur. The initial flow oscillations in the two halves of the loop are usually very nearly 180/sup 0/ out-of-phase. However, as the loop inventory is further decreased, an in-phase oscillation component is observed. In tests with two parallel, heated channels in each half-loop, oscillations associated with mass transfer between the channel pairs are also observed. Although flow oscillations can lead to intermittent dryout of the upper elements of the heater-rod assemblies in the horizontal channels, natural circulation cooling appears to be effective until about 50% of the loop inventory is drained; sustained flow stratification then occurs in the heated channels, leading to heater temperature excursions. The paper reviews the experimental results obtained and describes the evolution of natural circulation flow in particular cases as voidage is progressively increased. The stability behavior is discussed briefly with reference to a simple stability model.

Field errors in the RFX magnetic field configuration

International Nuclear Information System (INIS)

Bellina, F.; Campostrini, P.P.; Chitarin, G.; Fauri, M.; Zaccaria, P.L.

1987-01-01

Several factors can jeopardize the desired field configuration in the plasma region of a toroidal machine, namely: the wrong positioning of the coil conductors; the displacement of the coils due to the deflection of the mechanical structure; the currents in the busbars feeding the coils; the ferromagnetic materials around the machine; and the eddy currents in any conducting loop in the neighbourhood of the machine. This paper describes the various methods used for evaluating the effects of each item listed above and the technical solutions which have been adopted, case by case, in order to comply with the requirements on the field errors

The evolution mechanism of the dislocation loops in irradiated lanthanum doped cerium oxide

International Nuclear Information System (INIS)

Miao, Yinbin; Aidhy, Dilpuneet; Chen, Wei-Ying; Mo, Kun; Oaks, Aaron; Wolf, Dieter; Stubbins, James F.

2014-01-01

Cerium dioxide, a non-radioactive surrogate of uranium dioxide, is useful for simulating the radiation responses of uranium dioxide and mixed oxide fuel (MOX). Controlled additions of lanthanum can also be used to form various levels of lattice oxide or anion vacancies. In previous transmission electron microscopy (TEM) experimental studies, the growth rate of dislocation loops in irradiated lanthanum doped ceria was reported to vary with lanthanum concentration. This work reports findings of the evolution mechanisms of the dislocation loops in cerium oxide with and without lanthanum dopants based on a combination of molecular statics and molecular dynamics simulations. These dislocation loops are found to be b=1/3〈111〉 interstitial type Frank loops. Calculations of the defect energy profiles of the dislocation loops with different structural configurations and radii reveal the basis for preference of nucleation as well as the driving force of growth. Frenkel pair evolution simulations and displacement cascade overlaps simulations were conducted for a variety of lanthanum doping conditions. The nucleation and growth processes of the Frank loop were found to be controlled by the mobility of cation interstitials, which is significantly influenced by the lanthanum doping concentration. Competition mechanisms coupled with the mobility of cation point defects were discovered, and can be used to explain the lanthanum effects observed in experiments

Pulmonary arteriovenous malformation in cryptogenic liver

International Nuclear Information System (INIS)

Afzal, N.

2013-01-01

The cause in 10 - 20% cases of liver cirrhosis (LC) cannot be elucidated, and are thus termed cryptogenic. Pulmonary arteriovenous malformations (PAVMs) are relatively rare, but the most common anomaly involving the pulmonary tree. Although the rare correlation between LC and PAVM is well-known, there have been no reports of PAVMs occurring in cryptogenic LC. We report a case of PAVM that occurred in cryptogenic liver cirrhosis in a 3 years old male child. The child presented with complaints of malena, hematemesis and variceal bleed. The examination revealed a child with respiratory distress, irritability, tachycardia, clubbing and abdominal distention. He was worked up for recurrent variceal bleeding secondary to portal hypertension but the oxygen saturation during hospital stay kept deteriorating. The diagnosis of hepatopulmonary syndrome as the cause of persistent hypoxemia in the absence of other cardio-pulmonary causes was then made by enhanced echocardiogram using agitated saline. He improved significantly after liver transplantation performed abroad. At a 6 months follow-up, the child was stable with no evidence of intrapulmonary shunting on repeat echo. (author)

Endovascular treatment of intracranial arteriovenous malformations

International Nuclear Information System (INIS)

Seruga, T.

2002-01-01

Background. The aim of the study was the introduction of endovascular interventional treatment of cerebral arteriovenous malformations (AVM) with superselective embolization with cyanoacrylic polymerisation agent. Case reports. Endovascular embolization was performed in five patients with cerebral AVMs. Three of these patients were presented with intracerebral haemathomas whereas in other two patients, cerebral AVM was an incidental finding. Superselective catheterisation of AVMs was performed and acrylic glue was selectively injected into the nidus. Conclusions. Control cerebral angiography after embolization of AVM showed different results. In one patient, AVM was totally occluded after three sessions and in second case AVM was occluded in a single session. The rate of occlusion in other two cases was estimated between 70% in 80%. Both of these two patients underwent surgery. One patient is still in the process of treatment. Endovascular treatment of cerebral AVMs with superselective embolization with liquid cyanoacrilyc adhesive agent is a safe and effective alternative treatment paths next to microsurgery. Endovascular treatment in combination with radiosurgery could become the method of choice in the therapy of cerebral AVMs in the future. (author)

Blowout Surge due to Interaction between a Solar Filament and Coronal Loops

Energy Technology Data Exchange (ETDEWEB)

Li, Haidong; Jiang, Yunchun; Yang, Jiayan; Yang, Bo; Xu, Zhe; Bi, Yi; Hong, Junchao; Chen, Hechao [Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming, 650216 (China); Qu, Zhining, E-mail: lhd@ynao.ac.cn [Department of Physics, School of Science, Sichuan University of Science and Engineering, Zigong 643000 (China)

2017-06-20

We present an observation of the interaction between a filament and the outer spine-like loops that produces a blowout surge within one footpoint of large-scale coronal loops on 2015 February 6. Based the observation of the AIA 304 and 94 Å, the activated filament is initially embedded below a dome of a fan-spine configuration. Due to the ascending motion, the erupting filament reconnects with the outer spine-like field. We note that the material in the filament blows out along the outer spine-like field to form the surge with a wider spire, and a two-ribbon flare appears at the site of the filament eruption. In this process, small bright blobs appear at the interaction region and stream up along the outer spine-like field and down along the eastern fan-like field. As a result, a leg of the filament becomes radial and the material in it erupts, while another leg forms the new closed loops. Our results confirm that the successive reconnection occurring between the erupting filament and the coronal loops may lead to a strong thermal/magnetic pressure imbalance, resulting in a blowout surge.

Biodegradability of poly(3-hydroxybutyrate) film grafted with vinyl acetate: Effect of grafting and saponification

Science.gov (United States)

Wada, Yuki; Seko, Noriaki; Nagasawa, Naotsugu; Tamada, Masao; Kasuya, Ken-ichi; Mitomo, Hiroshi

2007-06-01

Radiation-induced graft polymerization of vinyl acetate (VAc) onto poly(3-hydroxybutyrate) (PHB) film was carried out. At a degree of grafting higher than 5%, the grafted films (PHB-g-VAc) completely lost the enzymatic degradability that is characteristic of PHB due to the grafted VAc covering the surface of the PHB film. However, the biodegradability of the PHB-g-VAc films was recovered when the films were saponified in alkali solution under optimum conditions. Graft chains of the PHB-g-VAc film reacted selectively to become biodegradable polyvinyl alcohol (PVA). The biodegradability of the saponified PHB-g-VAc film increased rapidly with time.

Biodegradability of poly(3-hydroxybutyrate) film grafted with vinyl acetate: Effect of grafting and saponification

International Nuclear Information System (INIS)

Wada, Yuki; Seko, Noriaki; Nagasawa, Naotsugu; Tamada, Masao; Kasuya, Ken-ichi; Mitomo, Hiroshi

2007-01-01

Radiation-induced graft polymerization of vinyl acetate (VAc) onto poly(3-hydroxybutyrate) (PHB) film was carried out. At a degree of grafting higher than 5%, the grafted films (PHB-g-VAc) completely lost the enzymatic degradability that is characteristic of PHB due to the grafted VAc covering the surface of the PHB film. However, the biodegradability of the PHB-g-VAc films was recovered when the films were saponified in alkali solution under optimum conditions. Graft chains of the PHB-g-VAc film reacted selectively to become biodegradable polyvinyl alcohol (PVA). The biodegradability of the saponified PHB-g-VAc film increased rapidly with time

Engineered, axially-vascularized osteogenic grafts from human adipose-derived cells to treat avascular necrosis of bone in a rat model.

Science.gov (United States)

Ismail, Tarek; Osinga, Rik; Todorov, Atanas; Haumer, Alexander; Tchang, Laurent A; Epple, Christian; Allafi, Nima; Menzi, Nadia; Largo, René D; Kaempfen, Alexandre; Martin, Ivan; Schaefer, Dirk J; Scherberich, Arnaud

2017-11-01

Avascular necrosis of bone (AVN) leads to sclerosis and collapse of bone and joints. The standard of care, vascularized bone grafts, is limited by donor site morbidity and restricted availability. The aim of this study was to generate and test engineered, axially vascularized SVF cells-based bone substitutes in a rat model of AVN. SVF cells were isolated from lipoaspirates and cultured onto porous hydroxyapatite scaffolds within a perfusion-based bioreactor system for 5days. The resulting constructs were inserted into devitalized bone cylinders mimicking AVN-affected bone. A ligated vascular bundle was inserted upon subcutaneous implantation of constructs in nude rats. After 1 and 8weeks in vivo, bone formation and vascularization were analyzed. Newly-formed bone was found in 80% of SVF-seeded scaffolds after 8weeks but not in unseeded controls. Human ALU+cells in the bone structures evidenced a direct contribution of SVF cells to bone formation. A higher density of regenerative, M2 macrophages was observed in SVF-seeded constructs. In both experimental groups, devitalized bone was revitalized by vascularized tissue after 8 weeks. SVF cells-based osteogenic constructs revitalized fully necrotic bone in a challenging AVN rat model of clinically-relevant size. SVF cells contributed to accelerated initial vascularization, to bone formation and to recruitment of pro-regenerative endogenous cells. Avascular necrosis (AVN) of bone often requires surgical treatment with autologous bone grafts, which is surgically demanding and restricted by significant donor site morbidity and limited availability. This paper describes a de novo engineered axially-vascularized bone graft substitute and tests the potential to revitalize dead bone and provide efficient new bone formation in a rat model. The engineering of an osteogenic/vasculogenic construct of clinically-relevant size with stromal vascular fraction of human adipose, combined to an arteriovenous bundle is described. This

Radiation grafting on natural films

Science.gov (United States)

Lacroix, M.; Khan, R.; Senna, M.; Sharmin, N.; Salmieri, S.; Safrany, A.

2014-01-01

Different methods of polymer grafting using gamma irradiation are reported in the present study for the preparation of newly functionalized biodegradable films, and some important properties related to their mechanical and barrier properties are described. Biodegradable films composed of zein and poly(vinyl alcohol) (PVA) were gamma-irradiated in presence of different ratios of acrylic acid (AAc) monomer for compatibilization purpose. Resulting grafted films (zein/PVA-g-AAc) had their puncture strength (PS=37-40 N mm-1) and puncture deformation (PD=6.5-9.8 mm) improved for 30% and 50% PVA in blend, with 5% AAc under 20 kGy. Methylcellulose (MC)-based films were irradiated in the presence of 2-hydroxyethyl methacrylate (HEMA) or silane, in order to determine the effect of monomer grafting on the mechanical properties of films. It was found that grafted films (MC-g-HEMA and MC-g-silane) using 35% monomer performed higher mechanical properties with PS values of 282-296 N mm-1 and PD of 5.0-5.5 mm under 10 kGy. Compatibilized polycaprolactone (PCL)/chitosan composites were developed via grafting silane in chitosan films. Resulting trilayer grafted composite film (PCL/chitosan-g-silane/PCL) presented superior tensile strength (TS=22 MPa) via possible improvement of interfacial adhesion (PCL/chitosan) when using 25% silane under 10 kGy. Finally, MC-based films containing crystalline nanocellulose (CNC) as a filling agent were prepared and irradiated in presence of trimethylolpropane trimethacrylate (TMPTMA) as a grafted plasticizer. Grafted films (MC-g-TMPTMA) presented superior mechanical properties with a TS of 47.9 MPa and a tensile modulus (TM) of 1792 MPa, possibly due to high yield formation of radicals to promote TMPTMA grafting during irradiation. The addition of CNC led to an additional improvement of the barrier properties, with a significant 25% reduction of water vapor permeability (WVP) of grafted films.

Random walk loop soups and conformal loop ensembles

NARCIS (Netherlands)

van de Brug, T.; Camia, F.; Lis, M.

2016-01-01

The random walk loop soup is a Poissonian ensemble of lattice loops; it has been extensively studied because of its connections to the discrete Gaussian free field, but was originally introduced by Lawler and Trujillo Ferreras as a discrete version of the Brownian loop soup of Lawler and Werner, a

Dispersion compensation in an open-loop all-optical chaotic communication system

International Nuclear Information System (INIS)

Liu Hui-Jie; Feng Jiu-Chao; Ren Bin

2012-01-01

The optical chaotic communication system using open-loop fiber transmission is studied under strong injection conditions. The optical chaotic communication system with open-loop configuration is studied using fiber transmission under strong injection conditions. The performances of fiber links composed of two types of fiber segments in different dispersion compensation maps are compared by testing the quality of the recovered message with different bit rates and encrypted by chaotic modulation (CM) or chaotic shift keying (CSK). The result indicates that the performance of the pre-compensation map is always worst. Two types of symmetrical maps are identical whatever the encryption method and bit-rate of message are. For the transmitting and the recovering of message of lower bit rate (1 Gb/s), the post-compensation map is the best scheme. However, for the message of higher bit rate (2.5 Gb/s), the parameters in communication system need to be modified properly in order to adapt to the high-speed application. Meanwhile, two types of symmetrical maps are the best scheme. In addition, the CM method is superior to the CSK method for high-speed applications. It is in accordance with the result in a back-to-back configuration system. (general)

Relationship between chromosome configurations/associations and nuclear size/shape

International Nuclear Information System (INIS)

Ostashevsky, J.Y.

2003-01-01

Full text: Chromosome configurations (linear,folded,loop,etc.,which are defined through a pattern of centromere and/or telomere anchoring to the nuclear membrane) and chromosome associations (homologous pairing, number of centromere or telomere clusters per nucleus, number of chromosome arms per cluster, etc.) are critical for the formation of radiation-induced chromosome aberrations and DSB repair. However, the rules of nuclear architecture are poorly understood. A polymer approach for chromosome configurations, associations, and attachments was developed, based on the coil-like behavior of chromosomal fibers and the tight packing of discrete chromatin domains in a nucleus. The model considers chromatin anchoring to nuclear structures and shows that confinement of chromatin diffusion in a nucleus can be related to its anchoring and higher-order chromatin structure. The model was applied to nuclei of budding and fission yeast, Drosophila, worm, newt, mammals (human, Indian and Chinese muntjac, mouse) and plants (Arabidopsis, maize, barley, wheat). Quantitative agreement between results calculated from the model and observed data was obtained in all considered (∼25) cases. This supports the model and means that permitted chromosome configurations and associations can be predicted from the geometrical constraints imposed on chromosomes by nuclear size and shape

Environmental application of radiation grafting

International Nuclear Information System (INIS)

Tamada, Masao

2007-01-01

Adsorbent having high selectivity against a certain metal ion was synthesized by means of radiation-induced graft polymerization for the purpose of environmental application. The resulting adsorbents were utilized for the removal of toxic metal from scallop waste and the collection of uranium from seawater. As a novel application of grafting, the biodegradability of poly-hydroxybutylate was controlled by grafting. The biodegradability could be depressed by the graft chain and then recovered by external stimuli such as thermal and chemical treatments. (author)

Graft union formation in Douglas-fir.

Science.gov (United States)

D.L. Copes

1969-01-01

Greenhouse-grown Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) graft unions were examined between 2 and 84 days after grafting. Room temperature was maintained at 60-70 F throughout the growing season. In most respects grafts of Douglas-fir followed development patterns previously reported for spruce and pine grafts, but specific differences...

Differential kinetics of response and toxicity using stereotactic radiation and interventional radiological coiling for pulmonary arterio-venous shunting from metastatic leiomyosarcoma

International Nuclear Information System (INIS)

Wong, Annie Ngai Man; Siva, Shankar; Chin, Kwang; Manser, Renee; Antippa, Phillip; Dowling, Richard; Mileshkin, Linda Rose

2015-01-01

Case report demonstrating the differential kinetics of response and toxicity using stereotactic radiation and interventional radiological coiling for pulmonary arterio-venous shunting from leiomyosarcoma pulmonary metastases.

Renormalization of loop functions for all loops

International Nuclear Information System (INIS)

Brandt, R.A.; Neri, F.; Sato, M.

1981-01-01

It is shown that the vacuum expectation values W(C 1 ,xxx, C/sub n/) of products of the traces of the path-ordered phase factors P exp[igcontour-integral/sub C/iA/sub μ/(x)dx/sup μ/] are multiplicatively renormalizable in all orders of perturbation theory. Here A/sub μ/(x) are the vector gauge field matrices in the non-Abelian gauge theory with gauge group U(N) or SU(N), and C/sub i/ are loops (closed paths). When the loops are smooth (i.e., differentiable) and simple (i.e., non-self-intersecting), it has been shown that the generally divergent loop functions W become finite functions W when expressed in terms of the renormalized coupling constant and multiplied by the factors e/sup -K/L(C/sub i/), where K is linearly divergent and L(C/sub i/) is the length of C/sub i/. It is proved here that the loop functions remain multiplicatively renormalizable even if the curves have any finite number of cusps (points of nondifferentiability) or cross points (points of self-intersection). If C/sub γ/ is a loop which is smooth and simple except for a single cusp of angle γ, then W/sub R/(C/sub γ/) = Z(γ)W(C/sub γ/) is finite for a suitable renormalization factor Z(γ) which depends on γ but on no other characteristic of C/sub γ/. This statement is made precise by introducing a regularization, or via a loop-integrand subtraction scheme specified by a normalization condition W/sub R/(C-bar/sub γ/) = 1 for an arbitrary but fixed loop C-bar/sub γ/. Next, if C/sub β/ is a loop which is smooth and simple except for a cross point of angles β, then W(C/sub β/) must be renormalized together with the loop functions of associated sets S/sup i//sub β/ = ]C/sup i/ 1 ,xxx, C/sup i//sub p/i] (i = 2,xxx,I) of loops C/sup i//sub q/ which coincide with certain parts of C/sub β/equivalentC 1 1 . Then W/sub R/(S/sup i//sub β/) = Z/sup i/j(β)W(S/sup j//sub β/) is finite for a suitable matrix Z/sup i/j

Graft-copolymerization onto carbon black

International Nuclear Information System (INIS)

Nakase, Yoshiaki; Nishii, Masanobu; Kijima, Toshiyuki; Kato, Hiroshi.

1988-07-01

Radiation-induced graft copolymerization of vinyl monomer onto carbon black was performed. During the γ-ray- and electron beam-induced polymerization (In-source), or the electron beam post-polymerization, the graft-copolymerization behavior was affected by the kinds of both carbon blacks and monomers, i.e. the smaller the size of carbon black particles, the higher the apparent grafted fraction. Homopolymer in the grafted carbon black samples was washed out by the solvent of the polymer, and the extracted polymer seemed to be dimer or trimer of the used monomer. In the case of the post-polymerization with the pre-irradiation doses of 50 Mrad, homopolymer was hardly observed. The polymer sheets of plastics or rubbers with grafted carbon black had an electrical conductivity unalterable considerably by the heating cycles. The particles of grafted carbon black in the sheet might be kept much more at the surface layer within 100 nm depth than at the inner layer. (author)

FAS grafted superhydrophobic ceramic membrane

Science.gov (United States)

Lu, Jun; Yu, Yun; Zhou, Jianer; Song, Lixin; Hu, Xingfang; Larbot, Andre

2009-08-01

The hydrophobic properties of γ-Al 2O 3 membrane have been obtained by grafting fluoroalkylsilane (FAS) on the surface of the membrane. The following grafting parameters were studied: the eroding time of the original membrane, the grafting time, the concentration of FAS solution and the multiplicity of grafting. Hydrophobicity of the membranes was characterized by contact angle (CA) measurement. The thermogravimetric analysis (TGA) was used to investigate the weight loss process (25-800 °C) of the fluoroalkylsilane grafted on Al 2O 3 powders under different grafting conditions. The morphologies of the membranes modified under different parameters were examined by field emission scanning electron microscopy (FE-SEM) and the surface roughness (Ra) was measured using white light interferometers. A needle-like structure was observed on the membrane surface after modification, which causes the change of Ra. On the results above, we speculated a model to describe the reaction between FAS and γ-Al 2O 3 membrane surface as well as the formed surface morphology.