WorldWideScience

Sample records for vessel occlusion model

  1. Title: Investigating the effects of a penetrating vessel occlusion with a multi-scale microvasculature model of the human cerebral cortex.

    Science.gov (United States)

    El-Bouri, Wahbi K; Payne, Stephen J

    2018-01-19

    The effect of the microvasculature on observed clinical parameters, such as cerebral blood flow, is poorly understood. This is partly due to the gap between the vessels that can be individually imaged in humans and the microvasculature, meaning that mathematical models are required to understand the role of the microvasculature. As a result, a multi-scale model based on morphological data was developed here that is able to model large regions of the human microvasculature. From this model, a clear layering of flow (and 1-dimensional depth profiles) was observed within a voxel, with the flow in the microvasculature being driven predominantly by the geometry of the penetrating vessels. It also appears that the pressure and flow are decoupled, both in healthy vasculatures and in those where occlusions have occurred, again due to the topology of the penetrating vessels shunting flow between them. Occlusion of a penetrating arteriole resulted in a very high degree of overlap of blood pressure drop with experimentally observed cell death. However, drops in blood flow were far more widespread, providing additional support for the theory that pericyte controlled regulation on the capillary scale likely plays a large part in the perfusion of tissue post-occlusion. Copyright © 2018. Published by Elsevier Inc.

  2. Temporal expression of extracellular matrix metalloproteinases and tissue plasminogen activator in the development of collateral vessels in the canine model of coronary occlusion.

    Science.gov (United States)

    Tyagi, S C; Kumar, S; Cassatt, S; Parker, J L

    1996-08-01

    Although heart attack is caused by occlusion of a major coronary artery, some patients have occlusion without heart attack because these patients have sufficient collateral circulation to provide an alternate pathway for blood supply to the myocardium at ischemic risk. The growth of new capillary vessels (angiogenesis) and enlargement of preexisting vessels play an important role in the collateral development. We evaluated the hypothesis that extracellular matrix metalloproteinase (MMP) expression is altered in coronary collateral arteries (0.5-1 mm o.d.) isolated from canine hearts 2-4 months after surgical placement of an ameroid occluder around the proximal left circumflex artery (n = 4), during the development of collateral vessels and restructuring new vessels. Histologic studies (hematoxylin and eosin, trichrome, and van Gieson stains) indicated cellular proliferation and increased collagen and elastin content in collateral vessels compared with comparable-sized unoccluded arterial segments of the left anterior descending (LAD) artery. In situ MMP activity of collateral vessels, measured using denatured collagen in the gel matrix, indicated an increase in total MMP activity in the intima of collateral vessels compared with normal LAD vessels. To further identify the type of MMP, tissue homogenates were prepared from collateral and LAD vessels and analyzed by SDS-PAGE zymography. The results suggest induction of gelatinase A and gelatinase B expression in collateral vessels compared with normal LAD tissue, when identical amounts of total protein were loaded onto each lane in the gel. Based on plasminogen-casein zymography, we observed the tissue plasminogen activator level to be increased in collateral vessels. On the basis of immunoblot and mRNA (Northern blot) analyses, we determined that the MMP-1 level was induced in collateral vessels 2 and 4 months after ameroid occlusion. In contrast with MMP-1, the level of TIMP-1 (tissue inhibitor of

  3. The dopamine agonists lisuride and piribedil protect against behavioural and histological changes following 4-vessel occlusion in the rat.

    Science.gov (United States)

    Caldwell, M A; Reymann, J M; Bentue-Ferrer, D; Allain, H; Leonard, B E

    1996-01-01

    The 4-vessel occlusion model of ischaemia in the rat was used to assess the effects of two dopaminergic agonists, lisuride and piribedil, on some behavioural and histological changes. Animals were either sham-operated, subjected to 20 min 4-vessel occlusion, or administered lisuride (0.5 mg/kg i.p.) or piribedil (10 mg/kg i.p.) 1 h before 20 min 4-vessel occlusion. Both drugs attenuated deficits in neurological testing, Morris water maze and 14-unit T-maze (p < 0.05). Extensive neuronal death was observed in the CA1, CA3 and CA4 regions of the hippocampus of 4-vessel-occluded animals. Pretreatment with both lisuride and piribedil provided protection against cell death in the hippocampal regions. These findings suggest dopamine may play a role in cerebral ischaemia and dopaminergic agonists may be beneficial in preventing ischaemia-induced neurodegeneration.

  4. Proximal Occlusion of Medium-Sized Vessels with the Penumbra Occlusion Device: A Study of Safety and Efficacy.

    Science.gov (United States)

    Jambon, E; Petitpierre, F; Brizzi, V; Dubuisson, V; Le Bras, Y; Grenier, N; Cornelis, F

    2017-02-01

    To retrospectively investigate the safety and efficacy of hybrid proximal coiling of various medium-sized vessels (4 to 8 mm) using the Penumbra Occlusion Device (POD). From October 2014 to February 2016, 37 proximal embolizations were performed with PODs in 36 patients (mean age: 50.8, range: 10-86; 29 male, 7 female). Vessel occlusions were achieved under fluoroscopic guidance using a 2.7 French microcatheter. Among the 36 vessels targeted, 16 were splenic arteries, 11 renal arteries, 4 mesenteric arteries, 3 arteriovenous fistulae, 1 iliac artery, and 1 gonadal vein. Intermittent follow-up angiography was performed to assess the flow for final occlusion. Outcomes and complications were assessed by clinical and/or imaging follow-up. To produce proximal occlusion of the intended vessels, the POD was used alone in 19 embolizations (51.4 %). In 12 procedures (32.4 %), POD was used as a coil constrainer to secure the coil construct. In 6 procedures (16.2 %), additional embolic devices were used to achieve vessel occlusion after initial POD deployment. After a mean follow-up of 3.2 months, no POD migration was observed but two complications occurred (5.4 %): one post embolic syndrome and one extensive infarction with splenic abscess. The POD system allows safe and effective proximal embolization of medium-sized vessels in a variety of clinical settings.

  5. Proximal Occlusion of Medium-Sized Vessels with the Penumbra Occlusion Device: A Study of Safety and Efficacy

    Energy Technology Data Exchange (ETDEWEB)

    Jambon, E.; Petitpierre, F. [Pellegrin Hospital, Department of Radiology (France); Brizzi, V.; Dubuisson, V. [Pellegrin Hospital, Department of Surgery (France); Bras, Y. Le; Grenier, N.; Cornelis, F., E-mail: cornelisfrancois@gmail.com [Pellegrin Hospital, Department of Radiology (France)

    2017-02-15

    PurposeTo retrospectively investigate the safety and efficacy of hybrid proximal coiling of various medium-sized vessels (4 to 8 mm) using the Penumbra Occlusion Device (POD).Materials and MethodsFrom October 2014 to February 2016, 37 proximal embolizations were performed with PODs in 36 patients (mean age: 50.8, range: 10–86; 29 male, 7 female). Vessel occlusions were achieved under fluoroscopic guidance using a 2.7 French microcatheter. Among the 36 vessels targeted, 16 were splenic arteries, 11 renal arteries, 4 mesenteric arteries, 3 arteriovenous fistulae, 1 iliac artery, and 1 gonadal vein. Intermittent follow-up angiography was performed to assess the flow for final occlusion. Outcomes and complications were assessed by clinical and/or imaging follow-up.ResultsTo produce proximal occlusion of the intended vessels, the POD was used alone in 19 embolizations (51.4 %). In 12 procedures (32.4 %), POD was used as a coil constrainer to secure the coil construct. In 6 procedures (16.2 %), additional embolic devices were used to achieve vessel occlusion after initial POD deployment. After a mean follow-up of 3.2 months, no POD migration was observed but two complications occurred (5.4 %): one post embolic syndrome and one extensive infarction with splenic abscess.ConclusionThe POD system allows safe and effective proximal embolization of medium-sized vessels in a variety of clinical settings.

  6. Estimation Of Blood Vessels Functional State By Means Of Analysis Of Temperature Reaction On Occlusive Test

    Directory of Open Access Journals (Sweden)

    A.P. Rytik

    2009-12-01

    Full Text Available Temperature reaction of distant phalanges in the case of the occlusive test has been registered. It has been revealed that the temperature reaction on the occlusive test for the group of patients with disturbances of vessel tone regulation differs from the reaction of norm group. Possible influence of vessel regulation state and volumetric blood supply on the skin temperature dynamics has been estimated. Diagnostic ability of the temperature occlusive test has been investigated

  7. Modeling of ultrathin occlusal veneers.

    Science.gov (United States)

    Magne, Pascal; Stanley, Kyle; Schlichting, Luís Henrique

    2012-07-01

    The purpose of this investigation was to compare stresses within bonded porcelain and composite resin ultra-thin occlusal veneers to restore advanced erosive lesions. A sound maxillary molar was digitized with a micro-CT scanner. The 2D image data were converted in a 3D model using an interactive medical image processing software (Mimics). Standard triangle language files (STL files) of enamel and dentin surfaces were then exported to the software 3-matic to execute design and meshing operations. Solid 3-dimensional (3-D) models acquired in a finite element software (Marc/Mentat) were subjected to nonlinear contact analysis to simulate occlusal loading at 200N and 800N. Values of maximum principal stress and ultimate tensile strength were used to calculate the risk of fracture and for validation with existing experimental data. There were marked differences in stress distributions both at 200N (maximum peak values of 21.59, 28.63, 31.04MPa) and 800N (96.16, 115.73, 134.90MPa) for all restorative materials (MZ100, Empress CAD and e.max CAD, respectively). High tensile stresses (measured in the central groove) were found at 800N with the ceramic occlusal veneers showing occlusal stress peaks 17-29% higher than composite resin. The estimated risk of fracture was decreased for ultrathin composite resin occlusal veneers, which correlated with the existing validation data. Ultra-thin composite resin (MZ100) and lithium disilicate (e.max CAD) occlusal veneers represent a conservative alternative to traditional onlays and complete coverage crowns for the treatment of severe erosive lesions in the posterior dentition. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  8. Bright vessel appearance on arterial spin labeling MRI for localizing arterial occlusion in acute ischemic stroke.

    Science.gov (United States)

    Yoo, Roh-Eul; Yun, Tae Jin; Rhim, Jung Hyo; Yoon, Byung-Woo; Kang, Koung Mi; Choi, Seung Hong; Kim, Ji-Hoon; Kim, Jeong Eun; Kang, Hyun-Seung; Sohn, Chul-Ho; Han, Moon Hee

    2015-02-01

    The purpose of this study was to evaluate whether bright vessel appearance on arterial spin labeling (ASL) MRI can help localize arterial occlusion sites in patients with acute ischemic stroke. Patients who underwent MRI for suspected acute ischemic stroke, as identified by an area of restricted diffusion, were included. All images were visually analyzed for the presence or absence of (1) arterial occlusion on time-of-flight MR angiography, (2) bright vessel appearance on ASL images, and (3) susceptibility vessel sign. McNemar 2-tailed test was used to compare the sensitivities of ASL and susceptibility-weighted imaging for the detection of arterial occlusion, using MR angiography as the reference standard. ASL bright vessel appearance was significantly more common in the group with occlusion than in the group without occlusion (94% [33 of 35] versus 21% [17 of 82], respectively; Pappearance, when present, was seen proximal or distal to the occlusion site. The bright vessel appearance had a significantly higher sensitivity for the detection of occlusion than the susceptibility vessel sign (94% [33 of 35] versus 66% [23 of 35], respectively; P=0.002). In cases with negative MR angiography, the bright vessel appearance helped identify more additional arterial occlusions than the susceptibility vessel sign (21% [17 of 82] versus 10% [8 of 82], respectively; P=0.012). The bright vessel appearance on ASL imaging can provide an important diagnostic clue for the detection and localization of arterial occlusion sites in patients with acute ischemic stroke. © 2014 American Heart Association, Inc.

  9. In vivo imaging of stepwise vessel occlusion in cerebral photothrombosis of mice by 19F MRI.

    Directory of Open Access Journals (Sweden)

    Gesa Weise

    Full Text Available (19F magnetic resonance imaging (MRI was recently introduced as a promising technique for in vivo cell tracking. In the present study we compared (19F MRI with iron-enhanced MRI in mice with photothrombosis (PT at 7 Tesla. PT represents a model of focal cerebral ischemia exhibiting acute vessel occlusion and delayed neuroinflammation.Perfluorocarbons (PFC or superparamagnetic iron oxide particles (SPIO were injected intravenously at different time points after photothrombotic infarction. While administration of PFC directly after PT induction led to a strong (19F signal throughout the entire lesion, two hours delayed application resulted in a rim-like (19F signal at the outer edge of the lesion. These findings closely resembled the distribution of signal loss on T2-weighted MRI seen after SPIO injection reflecting intravascular accumulation of iron particles trapped in vessel thrombi as confirmed histologically. By sequential administration of two chemically shifted PFC compounds 0 and 2 hours after illumination the different spatial distribution of the (19F markers (infarct core/rim could be visualized in the same animal. When PFC were applied at day 6 the fluorine marker was only detected after long acquisition times ex vivo. SPIO-enhanced MRI showed slight signal loss in vivo which was much more prominent ex vivo indicative for neuroinflammation at this late lesion stage.Our study shows that vessel occlusion can be followed in vivo by (19F and SPIO-enhanced high-field MRI while in vivo imaging of neuroinflammation remains challenging. The timing of contrast agent application was the major determinant of the underlying processes depicted by both imaging techniques. Importantly, sequential application of different PFC compounds allowed depiction of ongoing vessel occlusion from the core to the margin of the ischemic lesions in a single MRI measurement.

  10. Ovarian blood vessel occlusion as a surgical sterilization method in rats.

    Science.gov (United States)

    Murakami, Eduardo; Sartori de Camargo, Laíza; Freitas Cardoso, Karym Christine de; Miguel, Marina Pacheco; Tavares, Denise Cláudia; Santos Honsho, Cristiane dos; Ferreira de Souza, Fabiana

    2014-04-01

    To evaluate the female sterilization by occlusion of the ovarian blood flow, using the rat as experimental model. Fifty-five females rats were divided into four groups: I (n=10), bilateral ovariectomy, euthanized at 60 or 90 days; II (n=5), opening the abdominal cavity, euthanized at 90 days; III (n=20), bilateral occlusion of the ovarian blood supply using titanium clips, euthanized at 60 or 90 days; and IV (n=20), bilateral occlusion of the ovarian blood supply using nylon thread, euthanized at 60 or 90 days. The estrous cycle was monitored by vaginal cytology. After euthanasia, the reproductive tissues were evaluated histologically. Ovarian atresia was identified macroscopically at 60 days after surgery in the rats in groups III and IV; however, most of the rats in group III maintained cyclicity. Histology of the tissues from group IV revealed that the ovarian tissue was replaced by dense fibrous connective tissue that was slightly vascularized and that intact follicles were absent by 90 days. Ovarian blood vessels occluded caused ischemia, leading to progressive tissue necrosis, and bilateral occlusion using a nylon ligature is a viable method for surgical sterilization.

  11. Value of CT angiography in anterior circulation large vessel occlusive stroke: Imaging findings, pearls, and pitfalls

    Energy Technology Data Exchange (ETDEWEB)

    Power, Sarah, E-mail: drsarahpower@gmail.com [Department of Neuroradiology, Beaumont Hospital, P.O. Box 1297, Beaumont Rd, Dublin 9 (Ireland); McEvoy, Sinead H., E-mail: sineadmcevoy@beaumont.ie [Department of Neuroradiology, Beaumont Hospital, P.O. Box 1297, Beaumont Rd, Dublin 9 (Ireland); Cunningham, Jane, E-mail: janecunningham0708@gmail.com [Department of Radiology, Beaumont Hospital, P.O. Box 1297, Beaumont Rd, Dublin 9 (Ireland); Ti, Joanna P., E-mail: joannapearlyti@gmail.com [Department of Neuroradiology, Beaumont Hospital, P.O. Box 1297, Beaumont Rd, Dublin 9 (Ireland); Looby, Seamus, E-mail: seamuslooby@beaumont.ie [Department of Neuroradiology, Beaumont Hospital, P.O. Box 1297, Beaumont Rd, Dublin 9 (Ireland); O' Hare, Alan, E-mail: alanohare@beaumont.ie [Department of Neuroradiology, Beaumont Hospital, P.O. Box 1297, Beaumont Rd, Dublin 9 (Ireland); Williams, David, E-mail: davidwilliams@rcsi.ie [Department of Geriatrics and Stroke Medicine, Royal College of Surgeons in Ireland (RCSI) and Beaumont Hospital, P.O. Box 1297, Beaumont Rd, Dublin 9 (Ireland); Brennan, Paul, E-mail: paulbrennan@beaumont.ie [Department of Neuroradiology, Beaumont Hospital, P.O. Box 1297, Beaumont Rd, Dublin 9 (Ireland); Thornton, John, E-mail: johnthornton@beaumont.ie [Department of Neuroradiology, Beaumont Hospital, P.O. Box 1297, Beaumont Rd, Dublin 9 (Ireland)

    2015-07-15

    Highlights: • Site of occlusion determines potential collateralization routes and impacts outcome. • Multifocality of arterial occlusion is common, seen in approximately 20% of cases. • ICA false occlusion sign can be seen in setting of ICA stenosis or carotid T occlusion. • False patency sign: hyperdense thrombus/calcified occlusive plaque misinterpreted as patent vessel. • Additional abnormalities on CTA may infer stroke mechanism or alter decision making. - Abstract: Hyperacute stroke imaging is playing an increasingly important role in determining management decisions in acute stroke patients, particularly patients with large vessel occlusive stroke who may benefit from endovascular intervention. CT angiography (CTA) is an important tool in the work-up of the acute stroke patient. It reliably detects large occlusive thrombi in proximal cerebral arteries and is a quick and highly accurate method in identifying candidates for endovascular stroke treatment. In this article we review the imaging findings on CTA in acute large vessel occlusive stroke using a pictorial case based approach. We retrospectively reviewed CTA studies in 48 patients presenting with acute anterior circulation large vessel occlusive stroke who were brought for intra-arterial acute stroke intervention. We discuss and illustrate patterns of proximal intracranial arterial occlusion, collateralization to the occluded territory, as well as reviewing some important pearls, pitfalls and teaching points in CTA assessment of the acute stroke patient. Performed from the level of the aortic arch CTA also gives valuable information regarding the state of other vessels in the acute stroke patient, identifying additional significant vascular stenoses or occlusions, and as we illustrate, can demonstrate other clinically significant findings which may impact on patient management and outcome.

  12. Mechanical Recanalization of Subacute Vessel Occlusion in Peripheral Arterial Disease with a Directional Atherectomy Catheter

    Energy Technology Data Exchange (ETDEWEB)

    Massmann, Alexander, E-mail: Alexander.Massmann@uks.eu; Katoh, Marcus [Saarland University Hospital, Department of Diagnostic and Interventional Radiology (Germany); Shayesteh-Kheslat, Roushanak [Saarland University Hospital, Department of General Surgery, Visceral, Vascular, and Pediatric Surgery (Germany); Buecker, Arno [Saarland University Hospital, Department of Diagnostic and Interventional Radiology (Germany)

    2012-10-15

    Purpose: To retrospectively examine the technical feasibility and safety of directional atherectomy for treatment of subacute infrainguinal arterial vessel occlusions. Methods: Five patients (one woman, four men, age range 51-81 years) with peripheral arterial disease who experienced sudden worsening of their peripheral arterial disease-related symptoms during the last 2-6 weeks underwent digital subtraction angiography, which revealed vessel occlusion in native popliteal artery (n = 4) and in-stent occlusion of the superficial femoral artery (n = 1). Subsequently, all patients were treated by atherectomy with the SilverHawk (ev3 Endovascular, USA) device. Results: The mean diameter of treated vessels was 5.1 {+-} 1.0 mm. The length of the occlusion ranged 2-14 cm. The primary technical success rate was 100%. One patient experienced a reocclusion during hospitalization due to heparin-induced thrombocytopenia. There were no further periprocedural complications, in particular no peripheral embolizations, until hospital discharge or during the follow-up period of 1 year. Conclusion: The recanalization of infrainguinal arterial vessel occlusions by atherectomy with the SilverHawk device is technically feasible and safe. In our limited retrospective study, it was associated with a high technical success rate and a low procedure-related complication rate.

  13. Robust and enduring atorvastatin-mediated memory recovery following the 4-vessel occlusion/internal carotid artery model of chronic cerebral hypoperfusion in middle-aged rats.

    Science.gov (United States)

    Zaghi, Gislene Gonçalves Dias; Godinho, Jacqueline; Ferreira, Emilene Dias Fiuza; Ribeiro, Matheus Henrique Dal Molin; Previdelli, Isolde Santos; de Oliveira, Rúbia Maria Weffort; Milani, Humberto

    2016-02-04

    Chronic cerebral hypoperfusion (CCH) is a common condition associated with the development and/or worsening of age-related dementia.We previously reported persistent memory loss and neurodegeneration after CCH in middle-aged rats. Statin-mediated neuroprotection has been reported after acute cerebral ischemia. Unknown, however, is whether statins can alleviate the outcome of CCH. The present study investigated whether atorvastatin attenuates the cognitive and neurohistological outcome of CCH. Rats (12–15 months old) were trained in a non-food-rewarded radial maze, and then subjected to CCH. Atorvastatin (10 mg/kg, p.o.) was administered for 42 days or 15 days, beginning 5 h after the first occlusion stage. Retrograde memory performance was assessed at 7, 14, 21, 28, and 35 days of CCH, and expressed by “latency,” “number of reference memory errors” and “number of working memory errors.” Neurodegeneration was then examined at the hippocampus and cerebral cortex. Compared to sham, CCH caused profound and persistent memory loss in the vehicle-treated groups, as indicated by increased latency (91.2% to 107.3%) and number of errors (123.5% to 2508.2%), effects from which the animals did not spontaneously recover across time. This CCH-induced retrograde amnesia was completely prevented by atorvastatin (latency: −4.3% to 3.3%; reference/working errors: −2.5% to 45.7%), regardless of the treatment duration. This effect was sustained during the entire behavioral testing period (5 weeks), even after discontinuing treatment. This robust and sustained memory-protective effect of atorvastatin occurred in the absence of neuronal rescue (39.58% to 56.45% cell loss). We suggest that atorvastatin may be promising for the treatment of cognitive sequelae associated with CCH.

  14. Novel model of direct and indirect cost-benefit analysis of mechanical embolectomy over IV tPA for large vessel occlusions: a real-world dollar analysis based on improvements in mRS.

    Science.gov (United States)

    Mangla, Sundeep; O'Connell, Keara; Kumari, Divya; Shahrzad, Maryam

    2016-01-20

    Ischemic strokes result in significant healthcare expenditures (direct costs) and loss of quality-adjusted life years (QALYs) (indirect costs). Interventional therapy has demonstrated improved functional outcomes in patients with large vessel occlusions (LVOs), which are likely to reduce the economic burden of strokes. To develop a novel real-world dollar model to assess the direct and indirect cost-benefit of mechanical embolectomy compared with medical treatment with intravenous tissue plasminogen activator (IV tPA) based on shifts in modified Rankin scores (mRS). A cost model was developed including multiple parameters to account for both direct and indirect stroke costs. These were adjusted based upon functional outcome (mRS). The model compared IV tPA with mechanical embolectomy to assess the costs and benefits of both therapies. Direct stroke-related costs included hospitalization, inpatient and outpatient rehabilitation, home care, skilled nursing facilities, and long-term care facility costs. Indirect costs included years of life expectancy lost and lost QALYs. Values for the model cost parameters were derived from numerous resources and functional outcomes were derived from the MR CLEAN study as a reflective sample of LVOs. Direct and indirect costs and benefits for the two treatments were assessed using Microsoft Excel 2013. This cost-benefit model found a cost-benefit of mechanical embolectomy over IV tPA of $163 624.27 per patient and the cost benefit for 50 000 patients on an annual basis is $8 181 213 653.77. If applied widely within the USA, mechanical embolectomy will significantly reduce the direct and indirect financial burden of stroke ($8 billion/50 000 patients). Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  15. A transplanted kidney surviving total vessel occlusion and anuria.

    Science.gov (United States)

    El-Harakeh, M A; Barbari, A; Stephan, A; Saggi, S; Kilany, H; Barakeh, A

    2005-08-01

    We report a case of a 46-year-old white male with renal graft artery stenosis who developed acute renal shutdown with total anuria while on the ACE inhibitor lisinopril, one week following the discontinuation of aspirin. The serum creatinine was 8.5 mg/dl. Doppler ultrasound and MAG3 scintigraphy of the grafted kidney were highly suggestive of a viable but nonfunctioning kidney. A femoro-femoral bypass for total thrombosis of the right common iliac artery was performed distal to the occlusion. Immediate diuresis was obtained after establishing the bypass. Serum creatinine dropped to 1.35 mg/dl three days later. In this case we believe that the collateral circulation played a significant role in immediate recovery of kidney function by maintaining renal perfusion pressure and preventing acute tubular necrosis (ATN). We also believe that the ACE inhibitor might have contributed to salvaging the kidney by improving medullary oxygen balance and maintaining adequate medullary blood flow.

  16. Mobile Interventional Stroke Teams Lead to Faster Treatment Times for Thrombectomy in Large Vessel Occlusion.

    Science.gov (United States)

    Wei, Daniel; Oxley, Thomas J; Nistal, Dominic A; Mascitelli, Justin R; Wilson, Natalie; Stein, Laura; Liang, John; Turkheimer, Lena M; Morey, Jacob R; Schwegel, Claire; Awad, Ahmed J; Shoirah, Hazem; Kellner, Christopher P; De Leacy, Reade A; Mayer, Stephan A; Tuhrim, Stanley; Paramasivam, Srinivasan; Mocco, J; Fifi, Johanna T

    2017-12-01

    Endovascular recanalization treatment for acute ischemic stroke is a complex, time-sensitive intervention. Trip-and-treat is an interhospital service delivery model that has not previously been evaluated in the literature and consists of a shared mobile interventional stroke team that travels to primary stroke centers to provide on-site interventional capability. We compared treatment times between the trip-and-treat model and the traditional drip-and-ship model. We performed a retrospective analysis on 86 consecutive eligible patients with acute ischemic stroke secondary to large vessel occlusion who received endovascular treatment at 4 hospitals in Manhattan. Patients were divided into 2 cohorts: trip-and-treat (n=39) and drip-and-ship (n=47). The primary outcome was initial door-to-puncture time, defined as the time between arrival at any hospital and arterial puncture. We also recorded and analyzed the times of last known well, IV-tPA (intravenous tissue-type plasminogen activator) administration, transfer, and reperfusion. Mean initial door-to-puncture time was 143 minutes for trip-and-treat and 222 minutes for drip-and-ship ( P Stroke Scale for trip-and-treat compared with drip-and-ship ( P =0.0704). Compared with drip-and-ship, the trip-and-treat model demonstrated shorter treatment times for endovascular therapy in our series. The trip-and-treat model offers a valid alternative to current interhospital stroke transfers in urban environments. © 2017 American Heart Association, Inc.

  17. Large vessel occlusive disease associated with CREST syndrome and scleroderma.

    Science.gov (United States)

    Youssef, P; Englert, H; Bertouch, J

    1993-01-01

    OBJECTIVES--To report the cases of three patients with CREST syndrome and one patient with diffuse scleroderma who had severe macrovascular disease and only minimal vascular risk factors. METHODS--The medical histories, physical examinations, and results of clinical investigations were reviewed in four patients. RESULTS--These four patients had severe morbidity from macrovascular disease of the arms and legs in the presence of minimal underlying vascular risk factors. These patients represent 11% of the women with scleroderma seen at our hospital since 1974. This is a greater than threefold increase above the expected proportion of symptomatic vascular disease seen in population studies. In the patients with CREST syndrome, large vessel disease was first seen more than 10 years after the onset of Raynaud's phenomenon, which was the first manifestation of the disease. A pathological specimen of the ulnar artery from one patient showed severe luminal narrowing by an acellular material with no evidence of atheroma. CONCLUSIONS--These cases suggest an association of both the CREST syndrome and scleroderma with macrovascular disease. PMID:8323401

  18. Subadventitial techniques for chronic total occlusion percutaneous coronary intervention: The concept of "vessel architecture".

    Science.gov (United States)

    Azzalini, Lorenzo; Carlino, Mauro; Brilakis, Emmanouil S; Vo, Minh; Rinfret, Stéphane; Uretsky, Barry F; Karmpaliotis, Dimitri; Colombo, Antonio

    2017-03-17

    Despite improvements in guidewire technologies, the traditional antegrade wire escalation approach to chronic total occlusion (CTO) recanalization is successful in only 60-80% of selected cases. In particular, long, calcified, and tortuous occlusions are less successfully approached with a true-to-true lumen approach. Frequently, the guidewire tracks into the subadventitial space, with no guarantee of distal re-entry into the true lumen. The ability to manage the subadventitial space has been a key step in the tremendous improvement in success rates of contemporary CTO percutaneous coronary intervention (PCI), whether operating antegradely or retrogradely. A modern approach to CTO PCI involves understanding the concept of "vessel architecture," which is based on the distinction between coronary structures (occlusive plaque, comprising the disrupted intima and media, and the outer adventitia) and extravascular space. The vessel architecture represents a safe work environment for guidewire and device manipulation. This review provides an anatomy-based description of the concept of vessel architecture, along with a historical perspective of subadventitial techniques for CTO PCI, and outcome data of CTO PCI utilizing the subadventitial space. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  19. Progression of Diabetic Capillary Occlusion: A Model.

    Directory of Open Access Journals (Sweden)

    Xiao Fu

    2016-06-01

    Full Text Available An explanatory computational model is developed of the contiguous areas of retinal capillary loss which play a large role in diabetic maculapathy and diabetic retinal neovascularization. Strictly random leukocyte mediated capillary occlusion cannot explain the occurrence of large contiguous areas of retinal ischemia. Therefore occlusion of an individual capillary must increase the probability of occlusion of surrounding capillaries. A retinal perifoveal vascular sector as well as a peripheral retinal capillary network and a deleted hexagonal capillary network are modelled using Compucell3D. The perifoveal modelling produces a pattern of spreading capillary loss with associated macular edema. In the peripheral network, spreading ischemia results from the progressive loss of the ladder capillaries which connect peripheral arterioles and venules. System blood flow was elevated in the macular model before a later reduction in flow in cases with progression of capillary occlusions. Simulations differing only in initial vascular network structures but with identical dynamics for oxygen, growth factors and vascular occlusions, replicate key clinical observations of ischemia and macular edema in the posterior pole and ischemia in the retinal periphery. The simulation results also seem consistent with quantitative data on macular blood flow and qualitative data on venous oxygenation. One computational model applied to distinct capillary networks in different retinal regions yielded results comparable to clinical observations in those regions.

  20. Stroke severity and incidence of acute large vessel occlusions in patients with hyper-acute cerebral ischemia

    DEFF Research Database (Denmark)

    Hansen, Christine Kraup; Christensen, Anders Fogh; Ovesen, C

    2015-01-01

    vessel occlusions and describe the relations to the National Institutes of Health Stroke Scale (NIHSS), lesion site and time from symptom onset in unselected consecutive patients with hyper-acute cerebral ischemia. METHODS: A prospective single hospital registry was based on consecutive unselected...... patients admitted from July 2009 to December 2011 with symptoms of acute cerebral ischemia within 4.5 h from symptom onset. ICA, M1, M2, ACA, PCA, BA and VA were assed for occlusions. Best NIHSS-cut-off values were calculated based on sensitivity and specificity for detecting any, anterior and posterior...... occlusions and the effect of time after symptom onset was assessed. RESULTS: Six hundred thirty-seven patients, with admission NIHSS: 1-42, were included; 183 patients presented with acute vessel occlusions (28.7%) in 15 different combinations of occlusions. The best NIHSS-cut-off for detecting any occlusion...

  1. Spectral diffuse reflectance and autofluorescence imaging can perform early prediction of blood vessel occlusion in skin flaps.

    Science.gov (United States)

    Chen, Shuo; Zhu, Caigang; Hoe-Kong Chui, Christopher; Sheoran, Gyanendra; Tan, Bien-Keem; Liu, Quan

    2016-11-17

    Flap transfer has become a common technique in reconstructive surgery. However, a significant number of compromised skin flaps are not successfully salvaged because the current clinical method for flap assessment relies heavily on the clinician's experience. Vascular occlusion is the major reason for flap failure, thus the accurate and objective early prediction of blood vessel occlusion is vitally important. Our parallel point measurement study has demonstrated the great potential of joint diffuse reflectance and autofluorescence spectroscopy in the early detection and differentiation of venous and arterial occlusion in skin flaps. Unfortunately, the technique of point measurements is not suitable to examine a large skin flap when a high spatial resolution is required. In this study, we attempted to overcome this problem by performing spectral diffuse reflectance and autofluorescence imaging on a rat skin flap model. Both imaging data and reconstructed spectra were used to statistically differentiate control flaps, arterially occluded flaps and venously occluded flaps. Our preliminary results suggest that the technique of joint diffuse reflectance and autofluorescence spectroscopic imaging can achieve high classification accuracy thus could be used to detect and differentiate flaps with venous and arterial occlusion accurately at an early time point in a large skin flap. Typical reconstructed spectra of (a) diffuse reflectance and (b) autofluorescence after normalization. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. CONTACTLESS MEASUREMENT OF KEY PARAMETERS OF LIMB VESSELS ON AN OCCLUSAL PLETHYSMOGRAPHY METHOD

    Directory of Open Access Journals (Sweden)

    V. I. Kuznetsov

    2013-01-01

    Full Text Available The purpose of this publication – to familiarize the readers with the newest achievements in the field of vision   machine   technologies   with   regard to the   occlusal   plethysmography.   The   principle   of plethysmograph work is similar to a principle of mechanical occlusal plethysmograph work, with that only a difference that working measuring environment (gas or liquid is replaced with laser labels, and fixation of change of volume is made by machine vision with the subsequent computer processing. Application of laser technologies of machine vision in future considerably simplified process of diagnostics, will allow to carry out diagnostics repeatedly and under various conditions of, for example, case of external action on the examined finiteness of the of heat, cold, physical exercise, and so, is representative of more and accurate picture of the state of blood vessels in the dynamics.

  3. Relationship Between Lesion Topology and Clinical Outcome in Anterior Circulation Large Vessel Occlusions.

    Science.gov (United States)

    Rangaraju, Srikant; Streib, Christopher; Aghaebrahim, Amin; Jadhav, Ashutosh; Frankel, Michael; Jovin, Tudor G

    2015-07-01

    Diffusion-weighted imaging (DWI) Alberta Stroke Program Early CT Score (ASPECTS), a surrogate of infarct volume, predicts outcome in anterior large vessel occlusion strokes. We aim to determine whether topological information captured by DWI ASPECTS contributes additional prognostic value. Adults with intracranial internal carotid artery, M1 or M2 middle carotid artery occlusions who underwent endovascular therapy were included. The primary outcome measure was poor clinical outcome (3-month modified Rankin Scale score, 3-6). Prognostic value of the 10 DWI ASPECTS regions in predicting poor outcome was determined by multivariable logistic regression, controlling for final infarct volume, age, and laterality. Two hundred and thirteen patients (mean age, 66.1±14.5 years; median National Institutes of Health Stroke Scale, 15) were included. Inter-rater reliability was good for DWI ASPECTS (deep regions, κ=0.72; cortical regions, κ=0.63). All DWI ASPECTS regions with the exception of the putamen were significant predictors (PASPECTS regions was not observed. Using penalized multivariable logistic regression, only M4 (odds ratio, 2.82; 95% confidence interval, 1.39-5.76) and M6 (odds ratio, 2.45; 95% confidence interval, 1.15-5.3) involvement were associated with poor outcome. M6 involvement independently predicted poor outcome in right hemispheric strokes (odds ratio, 5.8; 95% confidence interval, 1.9-20.3), whereas M4 (odds ratio, 4.3; 95% confidence interval, 1.3-15.0) involvement predicted poor outcome in left hemispheric strokes adjusting for infarct volume. Topologic information modestly improved the predictive ability of a prognostic score that incorporates age, infarct volume, and hemorrhagic transformation. Involvement of the right parieto-occipital (M6) and left superior frontal (M4) regions affect clinical outcome in anterior large vessel occlusions over and above the effect of infarct volume and should be considered during prognostication. © 2015 American

  4. Radiofrequency ablation of lung metastases close to large vessels during vascular occlusion: preliminary experience.

    Science.gov (United States)

    de Baere, Thierry; Robinson, Joey Marie; Rao, Pramod; Teriitehau, Christophe; Deschamps, Frederic

    2011-06-01

    To report an initial prospective evaluation of the technical feasibility, efficacy, and safety of combining percutaneous temporary balloon occlusion (PBO) of a large pulmonary artery adjacent to a metastatic lung tumor treated with percutaneous radiofrequency (RF) ablation. In six patients, lung RF ablation with a multitined, expandable electrode with simultaneous PBO via femoral access was attempted with the use of digital angiography and multidetector computed tomography (CT). Follow-up imaging was obtained immediately after treatment, at 1-2 days, and at 2, 6, 9, and 12 months; positron emission tomography/CT was performed at 4 months. Metastases targeted measured 17-37 mm (22 ± 8) and were in contact with a pulmonary artery 3-5 mm. Temporary occlusion of the pulmonary arterial branch in contact with the tumor was technically possible in five of six patients. Postablation CT scans obtained within 2 days of the procedure showed ablation zones measuring 37-57 mm (47 ± 8) in their shortest diameter. Three patients developed lung infarction within 1 month after RF ablation, and two had to be readmitted. At 3 months after the procedure, four patients had persistent occlusion of the balloon-occluded vessel. No uptake was demonstrated 4 months after ablation; at 12 months, all tumors showed complete ablation on CT. RF ablation of lung tumors with PBO is a feasible technique, but it induces atelectasia and long-lasting vascular occlusion responsible for a high rate of readmission. The results of this small study warrant careful further exploration of the benefits of the technique, compared with RF ablation without PBO or other methods of ablative therapy. Copyright © 2011 SIR. Published by Elsevier Inc. All rights reserved.

  5. Pittsburgh Response to Endovascular therapy (PRE) score: optimizing patient selection for endovascular therapy for large vessel occlusion strokes.

    Science.gov (United States)

    Rangaraju, Srikant; Aghaebrahim, Amin; Streib, Christopher; Sun, Chung-Huan; Ribo, Marc; Muchada, Marion; Nogueira, Raul; Frankel, Michael; Gupta, Rishi; Jadhav, Ashutosh; Jovin, Tudor G

    2015-11-01

    Endovascular therapy seems to benefit a subset of patients with large vessel occlusion strokes. We aimed to develop a clinically useful tool to identify patients who are likely to benefit from endovascular therapy. In a derivation cohort of consecutively treated patients with anterior circulation large vessel occlusion (Grady Memorial Hospital, N=247), independent predictors (pPittsburgh Response to Endovascular therapy (PRE) score as a predictor of good outcome. The PRE score was validated in two institutional cohorts (University of Pittsburgh Medical Center (UPMC): N=393; Unitat d'Ictus Vall d'Hebron: N=204) and its discriminative power for good outcome was compared with other validated tools. Benefit of successful recanalization was assessed in PRE score groups. Independent predictors of good outcome in the derivation cohort (age, baseline National Institute of Health Stroke Scale (NIHSS) score and Alberta Stroke Program Early CT Score (ASPECTS)) were used in the model: PRE score=age (years)+2×NIHSS-10 × ASPECTS. PRE score was highly predictive of good outcome in the derivation cohort (area under the curve (AUC)=0.79) and validation cohorts (UPMC: AUC=0.79; UIVH: AUC=0.72) with comparable rates of good outcome in all PRE risk quartiles. PRE was superior to Totaled Health Risks In Vascular Events (THRIVE) (p=0.03) and Stroke Prognostication using Age and NIHSS (SPAN) (p=0.007), with a trend towards superiority to Houston Intra-Arterial Therapy 2 (HIAT2) (p=0.06) and iSCORE (p=0.051) in predicting good outcomes. Better outcomes were associated with successful recanalization in patients with PRE scores -24 to +49 but not in patients with PRE scores <-24 or ≥ 50. The PRE score is a validated tool that predicts outcomes and may facilitate patient selection for endovascular therapy in anterior circulation large vessel occlusions. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  6. Hypoattenuation on CTA images with large vessel occlusion: timing affects conspicuity

    Energy Technology Data Exchange (ETDEWEB)

    Dave, Prasham [University of Ottawa, MD Program, Faculty of Medicine, Ottawa, ON (Canada); Lum, Cheemun; Thornhill, Rebecca; Chakraborty, Santanu [University of Ottawa, Department of Radiology, Ottawa, ON (Canada); Ottawa Hospital Research Institute, Ottawa, ON (Canada); Dowlatshahi, Dar [Ottawa Hospital Research Institute, Ottawa, ON (Canada); University of Ottawa, Division of Neurology, Department of Medicine, Ottawa, ON (Canada)

    2017-05-15

    Parenchymal hypoattenuation distal to occlusions on CTA source images (CTASI) is perceived because of the differences in tissue contrast compared to normally perfused tissue. This difference in conspicuity can be measured objectively. We evaluated the effect of contrast timing on the conspicuity of ischemic areas. We collected consecutive patients, retrospectively, between 2012 and 2014 with large vessel occlusions that had dynamic multiphase CT angiography (CTA) and CT perfusion (CTP). We identified areas of low cerebral blood volume on CTP maps and drew the region of interest (ROI) on the corresponding CTASI. A second ROI was placed in an area of normally perfused tissue. We evaluated conspicuity by comparing the absolute and relative change in attenuation between ischemic and normally perfused tissue over seven time points. The median absolute and relative conspicuity was greatest at the peak arterial (8.6 HU (IQR 5.1-13.9); 1.15 (1.09-1.26)), notch (9.4 HU (5.8-14.9); 1.17 (1.10-1.27)), and peak venous phases (7.0 HU (3.1-12.7); 1.13 (1.05-1.23)) compared to other portions of the time-attenuation curve (TAC). There was a significant effect of phase on the TAC for the conspicuity of ischemic vs normally perfused areas (P < 0.00001). The conspicuity of ischemic areas distal to a large artery occlusion in acute stroke is dependent on the phase of contrast arrival with dynamic CTASI and is objectively greatest in the mid-phase of the TAC. (orig.)

  7. Neurocritical Care of Emergent Large-Vessel Occlusion: The Era of a New Standard of Care.

    Science.gov (United States)

    Al-Mufti, Fawaz; Dancour, Elie; Amuluru, Krishna; Prestigiacomo, Charles; Mayer, Stephan A; Connolly, E Sander; Claassen, Jan; Willey, Joshua Z; Meyers, Philip M

    2017-07-01

    Acute ischemic stroke continues to be one of the leading causes of morbidity and mortality worldwide. Recent advances in mechanical thrombectomy techniques combined with prereperfusion computed tomographic angiography for patient selection have revolutionized stroke care in the past year. Peri- and postinterventional neurocritical care of the patient who has had an emergent large-vessel occlusion is likely an equally important contributor to the outcome but has been relatively neglected. Critical periprocedural management issues include streamlining care to speed intervention, blood pressure optimization, reversal of anticoagulation, management of agitation, and selection of anesthetic technique (ie, general vs monitored anesthesia care). Postprocedural critical care issues that might modulate neurological outcome include blood pressure and glucose optimization, avoidance of fever or hyperoxia, fluid and nutritional management, and early integration of rehabilitation into the intensive care unit setting. In this review, we sought to lay down an evidence-based strategy for patients with acute ischemic stroke undergoing emergent endovascular reperfusion.

  8. Detection of single-phase CTA occult vessel occlusions in acute ischemic stroke using CT perfusion-based wavelet-transformed angiography

    Energy Technology Data Exchange (ETDEWEB)

    Kunz, Wolfgang G.; Sommer, Wieland H.; Meinel, Felix G.; Ertl-Wagner, Birgit; Thierfelder, Kolja M. [Ludwig-Maximilian-University Hospital Munich, Institute for Clinical Radiology, Munich (Germany); Havla, Lukas; Dietrich, Olaf [Ludwig-Maximilian-University Hospital Munich, Josef Lissner Laboratory for Biomedical Imaging of the Institute for Clinical Radiology, Munich (Germany); Dorn, Franziska [Ludwig-Maximilian-University Hospital Munich, Department of Neuroradiology, Munich (Germany); Buchholz, Grete [Ludwig-Maximilian-University Hospital Munich, Department of Neurology, Munich (Germany)

    2017-06-15

    To determine the detection rate of intracranial vessel occlusions using CT perfusion-based wavelet-transformed angiography (waveletCTA) in acute ischemic stroke patients, in whom single-phase CTA (spCTA) failed to detect an occlusion. Subjects were selected from a cohort of 791 consecutive patients who underwent multiparametric CT including whole-brain CT perfusion. Inclusion criteria were (1) significant cerebral blood flow (CBF) deficit, (2) no evidence of vessel occlusion on spCTA and (3) follow-up-confirmed acute ischemic infarction. waveletCTA was independently analysed by two readers regarding presence and location of vessel occlusions. Logistic regression analysis was performed to identify predictors of waveletCTA-detected occlusions. Fifty-nine patients fulfilled the inclusion criteria. Overall, an occlusion was identified using waveletCTA in 31 (52.5 %) patients with negative spCTA. Out of 47 patients with middle cerebral artery infarction, 27 occlusions (57.4 %) were detected by waveletCTA, mainly located in the M2 (15) and M3 segments (8). The presence of waveletCTA-detected occlusions was associated with larger CBF deficit volumes (odds ratio (OR) = 1.335, p = 0.010) and shorter times from symptom onset (OR = 0.306, p = 0.041). waveletCTA is able to detect spCTA occult vessel occlusions in about half of acute ischemic stroke patients and may potentially identify more patients eligible for endovascular therapy. (orig.)

  9. Pittsburgh outcomes after stroke thrombectomy score predicts outcomes after endovascular therapy for anterior circulation large vessel occlusions.

    Science.gov (United States)

    Rangaraju, Srikant; Liggins, John T P; Aghaebrahim, Amin; Streib, Christopher; Sun, Chung-Huan; Gupta, Rishi; Nogueira, Raul; Frankel, Michael; Mlynash, Michael; Lansberg, Maarten; Albers, Gregory; Jadhav, Ashutosh; Jovin, Tudor G

    2014-08-01

    Prognostication tools that predict good outcome in patients with anterior circulation large vessel occlusions after endovascular therapy are lacking. We aim to develop a tool that incorporates clinical and imaging data to predict outcomes after endovascular therapy. In a derivation cohort of anterior circulation large vessel occlusion stroke patients treated with endovascular therapy within 8 hours from time last seen well (n=247), we performed logistic regression to identify independent predictors of good outcome (90-day modified Rankin Scale, 0-2). Factors were weighted based on β-coefficients to derive the Pittsburgh Outcomes After Stroke Thrombectomy (POST) score. POST was validated in an institutional endovascular database (University of Pittsburgh Medical Center, n=393) and the Diffusion-Weighted Imaging Evaluation for Understanding Stroke Evolution Study-2 (DEFUSE-2) data set (n=105), as well as in patients treated beyond 8 hours (n=194) and in octogenarians (n=111). In the derivation cohort, independent predictors (PPittsburgh Medical Center, AUC=0.81; DEFUSE-2, AUC=0.86), as well as in patients treated beyond 8 hours (AUC, 0.85) and octogenarians (AUC=0.76). POST had better predictive accuracy for good and poor outcome than the ischemic stroke predictive risk score (iSCORE). POST score is a validated predictor of outcome in patients with anterior circulation large vessel occlusions after endovascular therapy. © 2014 American Heart Association, Inc.

  10. Modeling self-occlusions in dynamic shape and appearance tracking

    KAUST Repository

    Yang, Yanchao

    2013-12-01

    We present a method to track the precise shape of a dynamic object in video. Joint dynamic shape and appearance models, in which a template of the object is propagated to match the object shape and radiance in the next frame, are advantageous over methods employing global image statistics in cases of complex object radiance and cluttered background. In cases of complex 3D object motion and relative viewpoint change, self-occlusions and disocclusions of the object are prominent, and current methods employing joint shape and appearance models are unable to accurately adapt to new shape and appearance information, leading to inaccurate shape detection. In this work, we model self-occlusions and dis-occlusions in a joint shape and appearance tracking framework. Experiments on video exhibiting occlusion/dis-occlusion, complex radiance and background show that occlusion/dis-occlusion modeling leads to superior shape accuracy compared to recent methods employing joint shape/appearance models or employing global statistics. © 2013 IEEE.

  11. Deconstruction of Interhospital Transfer Workflow in Large Vessel Occlusion: Real-World Data in the Thrombectomy Era.

    Science.gov (United States)

    Ng, Felix C; Low, Essie; Andrew, Emily; Smith, Karen; Campbell, Bruce C V; Hand, Peter J; Crompton, Douglas E; Wijeratne, Tissa; Dewey, Helen M; Choi, Philip M

    2017-07-01

    Interhospital transfer is a critical component in the treatment of acute anterior circulation large vessel occlusive stroke transferred for mechanical thrombectomy. Real-world data for benchmarking and theoretical modeling are limited. We sought to characterize transfer workflow from primary stroke center (PSC) to comprehensive stroke center after the publication of positive thrombectomy trials. Consecutive patients transferred from 3 high-volume PSCs to a single comprehensive stroke center between January 2015 and August 2016 were included in a retrospective study. Factors associated with key time metrics were analyzed with emphasis on PSC intrahospital workflow. Sixty-seven patients were identified. Median age was 74 years (interquartile range [IQR], 63.5-78) and National Institutes of Health Stroke Scale 17 (IQR, 12-21). Median transfer time measured by PSC-door-to-comprehensive stroke center-door was 128 minutes (IQR, 107-164), of which 82.8% was spent at PSCs (door-in-door-out [DIDO]; 106 minutes; IQR, 86-143). The lengthiest component of DIDO was computed-tomography-to-retrieval-request (median 59.5 minutes; IQR, 44-83). The 37.3% had DIDO exceeding 120 minutes. DIDO times differed significantly between PSCs (P=0.01). In multivariate analyses, rerecruiting the initial ambulance crew for transfer (Pworkflow represents a major opportunity to expedite mechanical thrombectomy and improve patient outcomes. © 2017 American Heart Association, Inc.

  12. [Endovascular method of stopping gastric hemorrhages using temporary occlusion of the major vessels].

    Science.gov (United States)

    Losev, Iu A

    1978-04-01

    The author's method consists in temporary occlusion of the hepatic and splenic arteries; and contrast-medium or hemostatic sponge, introduced into the celiac trunk proximally to the site of the occlusion, propagate into the stomach artery. The method proved to be satisfactory in 8 patients.

  13. THE ROLE OF ECG IN LOCALIZING THE CULPRIT VESSEL OCCLUSION IN ACUTE ST SEGMENT ELEVATION MYOCARDICAL INFARCTION WITH ANGIOGRAPHIC CORRELATION

    Directory of Open Access Journals (Sweden)

    Markandeya Rao

    2015-12-01

    Full Text Available BACKGROUND & OBJECTIVES The Electrocardiogram remains a crucial tool in the identification and management of acute myocardial infarction. A detailed analysis of patterns of ST-segment elevation may influence decisions regarding the perfusion therapy. This study was undertaken to identify the culprit vessel from ECG in patients with acute ST elevation myocardial infarction and correlate with coronary angiogram. MATERIALS & METHODS This is a prospective study, conducted on 126 patients in Osmania General Hospital, Hyderabad. Patients with ST segment elevation from ECG was evaluated to identify culprit vessel and later correlated with coronary angiogram. RESULTS Amongst 126 patients in this study, 70 patients had anterior wall and 56 patients had inferior wall myocardial infarction. ST> 1mm in V4R, ST  V3/ST  LIII Lead II was the most sensitive and ratio of STV3/STLIII >1.2 was the most specific criteria. ST in inferior leads > 1mm had maximum sensitivity in localizing occlusion in proximal D1 occlusion proximal to S1 as well. Absence of ST i in inferior leads is the most sensitive criteria in occlusion distal to S1 as well as in distal D1 in AWMI. CONCLUSION The admission ECG in patients with ST elevation AMI is valuable not only for determining early reperfusion treatment, but also provides important information to guide clinical decision-making.

  14. Incomplete Large Vessel Occlusions in Mechanical Thrombectomy: An Independent Predictor of Favorable Outcome in Ischemic Stroke.

    Science.gov (United States)

    Maus, Volker; You, Seunghwa; Kalkan, Alev; Borggrefe, Jan; Kabbasch, Christoph; Barnikol, Utako Birgit; Stetefeld, Henning; Dohmen, Christian; Liebig, Thomas; Fink, Gereon Rudolf; Mpotsaris, Anastasios

    2017-01-01

    Cerebral large vessel occlusion (LVO) in acute ischemic stroke (AIS) may be complete (CLVO) or incomplete (ILVO). The influence of ILVO on clinical outcome after mechanical thrombectomy (MT) remains unclear. We investigated primarily the clinical outcome in patients with AIS due to ILVO or CLVO. Five hundred three consecutive AIS patients with LVO treated with stent-retriever or direct aspiration-based MT between 2010 and 2016 were analyzed. The primary endpoint was favorable clinical outcome (modified Rankin Scale ≤2) at 90 days; secondary endpoints were periprocedural parameters. Forty-nine patients (11.3%) with a median National Institutes of Health Stroke Scale (NIHSS) of 11 presented with ILVO and the remainder presented with CLVO and median NIHSS of 15 (p < 0.001). The median groin puncture-to-reperfusion time was 30 vs. 67 min, respectively (p < 0.001). Successful reperfusion was reached in 47 out of 49 ILVO (95.9%) vs. 298 out of 381 CLVO (78.2%; p < 0.005) with less retrieval maneuvers (1.7 ± 2.2 vs. 3.0 ± 2.5; p < 0.001). The favorable outcome at 90 days was 81% in patients with ILVO vs. 29.1% in CLVO (p < 0.001); respective all-cause mortality rates were 6.4 vs. 28.5% (p < 0.001). Periprocedural complications (6.9%) occurred exclusively in CLVO patients (p < 0.05). ILVO was associated with favorable clinical outcome independent of age and NIHSS in multivariate logistic regression both in the anterior (OR 3.6; 95% CI 1.8-6.9; p < 0.001) and posterior circulation (OR 3.5; 95% CI 1.8-6.9; p < 0.001). AIS due to ILVO is frequent and is associated with a nearly threefold higher chance of favorable clinical outcome at 90 days, independent of age and initial NIHSS compared to CLVO. © 2017 S. Karger AG, Basel.

  15. Genistein, an isoflavone included in soy, inhibits thrombotic vessel occlusion in the mouse femoral artery and in vitro platelet aggregation.

    Science.gov (United States)

    Kondo, Kazunao; Suzuki, Yasuhiro; Ikeda, Yasuhiko; Umemura, Kazuo

    2002-11-22

    Diet can be the most important factor that influences risks for cardiovascular diseases. Genistein included in soy is one candidate that may benefit the cardiovascular system. Here, we investigated the inhibitory effects of genistein on thrombotic vessel occlusion in the mouse femoral artery using a photochemical reaction, and in vitro platelet aggregation in whole blood measured by single platelet counting. Genistein (10 mg/kg), intravenously administered 10 min before the rose bengal injection, significantly prolonged the thrombotic occlusion time from 6.1+/-0.4 to 8.4+/-0.8 min (PGenistein at doses higher than 30 microM significantly (Pgenistein was intravenously administered, ex vivo platelet aggregation induced by collagen (1 and 3 microg/ml) was significantly suppressed (Pgenistein prevented in vivo thrombogenesis and suppressed in vitro platelet aggregation. These results suggest that dietary supplementation of soy may prevent the progression of thrombosis and atherosclerosis.

  16. Candesartan pretreatment is cerebroprotective in a rat model of endothelin-1-induced middle cerebral artery occlusion

    Science.gov (United States)

    Mecca, Adam P.; O’Connor, Timothy E.; Katovich, Michael J.; Sumners, Colin

    2009-01-01

    Endogenous levels of angiotensin II (Ang II) are increased in the cortex and hypothalamus following stroke, and Ang II type 1 receptor blockers (ARBs) have been shown to attenuate the deleterious effects in animal stroke models using middle cerebral artery (MCA) intraluminal occlusion procedures. However, the endothelin-1 (ET-1)-induced middle cerebral artery occlusion (MCAO) model of cerebral ischaemia is thought to more closely mimic the temporal events of an embolic stroke. This method provides rapid occlusion of the MCA and a gradual reperfusion that lasts for 16–22 h. The aim of the present study was to evaluate whether systemic administration of an ARB prior to ET-1-induced MCAO would provide cerebroprotection during this model of ischaemic stroke. Injection of 3 μl of 80 μm ET-1 adjacent to the MCA resulted in complete occlusion of the vessel that resolved over a period of 30–40 min. Following ET-1-induced MCAO, rats had significant neurological impairment, as well as an infarct that consisted of 30% of the ipsilateral grey matter. Systemic pretreatment with 0.2 mg kg−1 day−1 candesartan for 7 days attenuated both the infarct size and the neurological deficits caused by ET-1-induced MCAO without altering blood pressure. This study confirms the cerebroprotective properties of ARBs during ischaemic stroke and validates the ET-1-induced MCAO model for examination of the role of the brain renin–angiotensin system in ischaemic stroke. PMID:19429641

  17. Open Embolectomy of Large Vessel Occlusion in the Endovascular Era: Results of a 12-Year Single-Center Experience.

    Science.gov (United States)

    Horiuchi, Tetsuyoshi; Nitta, Junpei; Miyaoka, Yoshinari; Nagm, Alhusain; Tsutsumi, Keiji; Ito, Kiyoshi; Hongo, Kazuhiro

    2017-06-01

    Mechanical endovascular embolectomy using stent retrievers has gained popularity for treatment of large vessel occlusion in acute ischemic stroke. Use of open embolectomy as a direct surgical treatment has been limited, likely owing to the technical difficulty, therapeutic time window, and time-consuming procedure. We retrospectively reviewed clinical and radiographic records of patients who underwent open embolectomy for major artery occlusion at an acute stage. Clinical features, complications, and outcome of patients were analyzed. From January 2004 to September 2016, 153 patients underwent 157 open embolectomies for major artery occlusion. Complete recanalization was achieved in 96.2% of patients. A favorable outcome was observed in 43.9%. Cerebral aneurysm along the occluded artery was observed in 11 patients with 12 aneurysms. Open embolectomy resulted in a high complete recanalization rate with an acceptable safety profile. Open embolectomy is a safe and durable method of cerebral recanalization in patients with embolic stroke and can be considered as a potential treatment if endovascular embolectomy cannot be performed. The details of the occluded arteries presented here will be useful for endovascular surgeons to prevent complications. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Outcome of patients with proximal vessel occlusion of the anterior circulation and DWI-PWI mismatch is time-dependent.

    Science.gov (United States)

    Mundiyanapurath, Sibu; Diatschuk, Sascha; Loebel, Sarah; Pfaff, Johannes; Pham, Mirko; Möhlenbruch, Markus Alfred; Wick, Wolfgang; Bendszus, Martin; Ringleb, Peter A; Radbruch, Alexander

    2017-06-01

    Patients with ischemic stroke and large vessel occlusion are assumed to benefit from endovascular therapy (ET) independent of the symptom onset-to-treatment time (OTT) if they present with a mismatch of diffusion- and perfusion-weighted imaging (DWI-PWI mismatch). We aimed at studying the influence of OTT on clinical outcome in these patients. Retrospective database review in a tertiary care university hospital. All patients presented with proximal vessel occlusion of the anterior circulation and DWI-PWI mismatch. Primary outcome was the influence of OTT on modified Rankin scale (mRS) score three months after treatment, dichotomized in favourable (0-2) and unfavourable outcome (3-6). Secondary outcome was the effect of OTT on the shift of the mRS score. Patients treated within an early time window (PWI mismatch according to the definitions from large trials (DEFUSE 2, DEFUSE 3, SWIFT-PRIME, EXTEND-IA). Outcome of patients with comparable DWI-PWI mismatch is time-dependent. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Extracranial-intracranial bypass and vessel occlusion for the treatment of unclippable giant middle cerebral artery aneurysms.

    Science.gov (United States)

    Kalani, M Yashar S; Zabramski, Joseph M; Hu, Yin C; Spetzler, Robert F

    2013-03-01

    Giant middle cerebral artery (MCA) aneurysms pose management challenges. To review the outcomes of patients with giant MCA aneurysms not amenable to clipping or vessel reconstruction treated with extracranial-intracranial (EC-IC) bypass and vessel sacrifice. We retrospectively reviewed a database of aneurysms treated at our institution between 1983 and 2011. Sixteen patients (11 males, 5 females) were identified. There were 10 saccular, 4 fusiform, and 2 serpentine aneurysms. The aneurysms predominantly involved the M1 segment in 5 cases, M2 in 9 cases, and both M1 and M2 in 2 cases. The EC-IC bypasses performed included 13 superficial temporal artery-MCA, 1 saphenous vein graft-MCA, and 2 radial artery grafts-MCA. The postoperative bypass patency rate was 93.8% (15/16). There were 3 cerebrovascular accidents (18.8%), but no perioperative deaths (0% mortality). The mean follow-up was 58.4 months (range, 1-265; median, 23.5 months). In 75% (12/16) of cases the aneurysms were occluded successfully. A small residual was noted in 3 cases with the use of this treatment strategy, and they were re-treated. In a fourth case treated with partial distal occlusion, reduced flow through the aneurysm was noted postoperatively, but the patient did not undergo further treatment. The mean modified Rankin scale and mean Glasgow Outcome Scale scores at last follow-up were 1.6 (range, 1-4; median, 1) and 4.8 (range, 3-5; median, 5), respectively. Giant MCA aneurysms are challenging lesions. EC-IC bypass with parent vessel occlusion can provide a durable form of treatment with acceptable rates of morbidity and mortality.

  20. Successful Treatment of Twin—Twin Transfusion Syndrome by Occlusion of Placental Vessel Anastomoses Using Enbucrilate

    Directory of Open Access Journals (Sweden)

    Ting-Yu Yang

    2008-09-01

    Conclusion: Targeted therapeutic ablation of vessel anastomoses involved in twin—twin transfusion syndrome using color Doppler ultrasonographic guidance is minimally invasive and may effectively obliterate interfetal transfusion, contributing to the survival of both twins.

  1. Density of thrombus on admission CT predicts revascularization efficacy in large vessel occlusion acute ischemic stroke.

    Science.gov (United States)

    Moftakhar, Parham; English, Joey D; Cooke, Daniel L; Kim, Warren T; Stout, Charles; Smith, Wade S; Dowd, Christopher F; Higashida, Randall T; Halbach, Van V; Hetts, Steven W

    2013-01-01

    Can lysability of large vessel thrombi in acute ischemic stroke be predicted by measuring clot density on admission nonenhanced CT (NECT), postcontrast enhanced CT, or CT angiogram (CTA)? We retrospectively studied 90 patients with acute large vessel ischemic strokes treated with intravenous (IV) tPA, intra-arterial (IA) tPA, and/or mechanical thrombectomy devices. Clot density [in Hounsfield unit (HU)] was measured on NECT, postcontrast enhanced CT, and CTA. Recanalization was assessed by the Thrombolysis in Cerebral Infarction grading system (TICI) on digital subtraction angiography. Thrombus density on preintervention NECT correlated with postintervention TICI grade regardless of pharmacological (IV tPA r=0.69, IA tPA r=0.72, Padmission NECT provides a rapid method to analyze clot composition, a potentially useful discriminator in selecting the most appropriate reperfusion strategy for an individual patient.

  2. The Dual Role of Cerebral Autoregulation and Collateral Flow in the Circle of Willis After Major Vessel Occlusion.

    Science.gov (United States)

    Kennedy McConnell, Flora; Payne, Stephen

    2017-08-01

    Ischaemic stroke is a leading cause of death and disability. Autoregulation and collateral blood flow through the circle of Willis both play a role in preventing tissue infarction. To investigate the interaction of these mechanisms a one-dimensional steady-state model of the cerebral arterial network was created. Structural variants of the circle of Willis that present particular risk of stroke were recreated by using a network model coupled with: 1) a steady-state physiological model of cerebral autoregulation; and 2) one wherein the cerebral vascular bed was modeled as a passive resistance. Simulations were performed in various conditions of internal carotid and vertebral artery occlusion. Collateral flow alone is unable to ensure adequate blood flow ([Formula: see text] normal flow) to the cerebral arteries in several common variants during internal carotid artery occlusion. However, compared to a passive model, cerebral autoregulation is better able to exploit available collateral flow and maintain flows within [Formula: see text] of baseline. This is true for nearly all configurations. Hence, autoregulation is a crucial facilitator of collateral flow through the circle of Willis. Impairment of this response during ischemia will severely impact cerebral blood flows and tissue survival, and hence, autoregulation should be monitored in this situation.

  3. Penumbra Stroke System as an ''add-on'' for the treatment of large vessel occlusive disease following thrombolysis: first results

    Energy Technology Data Exchange (ETDEWEB)

    Struffert, Tobias; Engelhorn, Tobias; Richter, Gregor; Doerfler, Arnd [University of Erlangen-Nuremberg, Department of Neuroradiology, Erlangen (Germany); Koehrmann, Martin; Nowe, Tim; Schellinger, Peter D.; Schwab, Stefan [University of Erlangen-Nuremberg, Department of Neurology, Erlangen (Germany)

    2009-09-15

    The Penumbra Stroke System (PSS) was cleared for use in patients with ischemic stroke by the FDA in January 2008. We describe our experience of using this new system in acute large vessel occlusive disease following thrombolysis. Fifteen consecutive patients (mean age 60 years) suffering from acute ischemic stroke were treated with the PSS after intravenous or intra-arterial standard treatment with tissue plasminogen activator (n = 14) or ReoPro (n = 1). All patients presented with TIMI 3 before use of the PSS. Carotid stenting (n = 3) and intracranial balloon angioplasty or stenting (n = 2) were performed if indicated. Neurological evaluation was performed using the NIHSS score and the mRS score. Initial median NIHSS score in 12 patients with occlusions in the anterior circulation was 15; three patients with basilar artery occlusion presented with coma. Median symptom to procedure start time was 151 min. In the anterior circulation, 9 of the 12 target vessels were recanalised successfully (TIMI 2 and 3). The rate of patients with independent clinical outcome (mRS {<=} 2) was 42%. One patient died 5 days after unsuccessful treatment, one after 28 days and one after 85 days owing to heart attack. Basilar artery occlusions could be recanalised in all cases to TIMI 3. The clinical result after 90 days was mRS 4 in two cases and mRS 5 in one case. Symptomatic haemorrhage did not occur. The PSS can safely be used for recanalisation in patients with acute ischemic stroke due to large vessel occlusion, who have already received thrombolysis treatment. The recanalisation rate was 80%. Symptomatic haemorrhage did not occur. Randomized trials may demonstrate that endovascular mechanical thrombectomy improves patient outcome. (orig.)

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

    Science.gov (United States)

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

    2017-03-01

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

  5. Experimental model of occlusal trauma in mouse periodontal tissues.

    OpenAIRE

    Fujii, T; Takaya, T; Mimura, H; Osuga, N; Matsuda, S; Nakano, K

    2014-01-01

    The aim of this study was to establish a model, which can be used to investigate the response of periodontal tissues to excessive occlusal loading in mice by observing histopathological changes. The experiment was performed on ten 7-week-old ddY male mice. Under general anesthesia by intraperitoneal injectionpentobarbital sodium, a micro-plus-screwpin (head part, 1.7mm in diameter, thickness 0.5mm thickness) was screwed into the pulp cavity of the upper-left-first molar. R_mCT images of the e...

  6. Mechanical Thrombectomy for Minor and Mild Stroke Patients Harboring Large Vessel Occlusion in the Anterior Circulation: A Multicenter Cohort Study.

    Science.gov (United States)

    Dargazanli, Cyril; Arquizan, Caroline; Gory, Benjamin; Consoli, Arturo; Labreuche, Julien; Redjem, Hocine; Eker, Omer; Decroix, Jean-Pierre; Corlobé, Astrid; Mourand, Isabelle; Gaillard, Nicolas; Ayrignac, Xavier; Charif, Mahmoud; Duhamel, Alain; Labeyrie, Paul-Emile; Riquelme, Carlos; Ciccio, Gabriele; Smajda, Stanislas; Desilles, Jean-Philippe; Gascou, Grégory; Lefèvre, Pierre-Henri; Mantilla-García, Daniel; Cagnazzo, Federico; Coskun, Oguzhan; Mazighi, Mikael; Riva, Roberto; Bourdain, Frédéric; Labauge, Pierre; Rodesch, Georges; Obadia, Michael; Bonafé, Alain; Turjman, Francis; Costalat, Vincent; Piotin, Michel; Blanc, Raphaël; Lapergue, Bertrand

    2017-12-01

    Proximal large vessel occlusion (LVO) is present in up to 30% of minor strokes. The effectiveness of mechanical thrombectomy (MT) in the subgroup of minor stroke with LVO in the anterior circulation is still open to debate. Data about MT in this subgroup of patients are sparse, and their optimal management has not yet been defined. The purpose of this multicenter cohort study was to evaluate the effectiveness of MT in patients experiencing acute ischemic stroke (AIS) because of LVO in the anterior circulation, presenting with minor-to-mild stroke symptoms (National Institutes of Health Stroke Scale score of stroke centers having 2 therapeutic approaches (urgent thrombectomy associated with best medical treatment [BMT] versus BMT first and MT if worsening occurs) about management of patients with minor and mild acute ischemic stroke harboring LVO in the anterior circulation. An intention-to-treat analysis was conducted. The primary end point was the rate of excellent outcome defined as the achievement of a modified Rankin Scale score of 0 to 1 at 3 months. Three hundred one patients were included, 170 with urgent MT associated with BMT, and 131 with BMT alone as first-line treatment. Patients treated with MT were younger, more often received intravenous thrombolysis, and had shorter time to imaging. Twenty-four patients (18.0%) in the medical group had rescue MT because of neurological worsening. Overall, excellent outcome was achieved in 64.5% of patients, with no difference between the 2 groups. Stratified analysis according to key subgroups did not find heterogeneity in the treatment effect size. Minor-to-mild stroke patients with LVO achieved excellent and favorable functional outcomes at 3 months in similar proportions between urgent MT versus delayed MT associated with BMT. There is thus an urgent need for randomized trials to define the effectiveness of MT in this patient subgroup. © 2017 American Heart Association, Inc.

  7. Altered low frequency oscillations of cortical vessels in patients with cerebrovascular occlusive disease – a NIRS study

    Directory of Open Access Journals (Sweden)

    Dorte ePhillip

    2013-12-01

    Full Text Available Analysis of cerebral autoregulation by measuring spontaneous oscillations in the low frequency spectrum of cerebral cortical vessels might be a useful tool for assessing risk and investigating different treatment strategies in carotid artery disease (CAD and stroke. Near infrared spectroscopy (NIRS is a non-invasive optical method to investigate regional changes in oxygenated (oxyHb and deoxygenated hemoglobin (deoxyHb in the outermost layers of the cerebral cortex. In the present study we examined oxyHb low frequency oscillations (LFOs, believed to reflect cortical cerebral autoregulation, in 16 patients with both symptomatic carotid occlusive disease and cerebral hypoperfusion in comparison to healthy controls. Each hemisphere was examined with 2 NIRS channels using a 3 cm source detector distance. Arterial blood pressure (ABP was measured via a finger plethysmograph. Using transfer function analysis ABP-oxyHb phase shift and gain as well as inter-hemispheric phase shift and amplitude ratio were assessed. We found that inter-hemispheric amplitude ratio was significantly altered in hypoperfusion patients compared to healthy controls (P= 0.010, because of relatively lower amplitude on the hypoperfusion side. The inter-hemispheric phase shift showed a trend (P = 0.061 towards increased phase shift in hypoperfusion patients compared to controls. We found no statistical difference between hemispheres in hypoperfusion patients for phase shift or gain values. There were no differences between the hypoperfusion side and controls for phase shift or gain values. These preliminary results suggest an impairment of autoregulation in hypoperfusion patients at the cortical level using NIRS.

  8. Dwell Time Of Stentriever Influences Complete Revascularisation And First Pass Tici3 Revascularisation In Acute Large Vessel Occlusive Stroke.

    Science.gov (United States)

    Kannath, Santhosh Kumar; Rajan, Jayadevan Enakshy; N, Sylaja Padmavathy; P, Sankara Sarma; Sukumaran, Sajith; Sreedharan, Sapna Erat; Kapilamoorthy, Tirur Raman

    2017-11-04

    In acute ischemic stroke with large vessel occlusion, the interaction between the clot retriever and the stent is critical for achieving successful recanalization. The ideal time of stent deployment (dwell time, DT) to improve revascularization is currently unknown., We systematically analysed the effect of different DT on final angiographic and clinical outcome of of patients who underwent mechanical thrombectomy. The DT was progressively increased from 3 minutes to 5 minutes and later, 8 minutes during the study period. The effect of DT on recanalization attempts, successful angiographic outcome (TICI 2B or 3), total revascularisation time, immediate and 3 month clinical outcomes were evaluated. The DT of 3 minutes and 5 minutes (DT3-5) was compared against DT of 8 minutes(DT8). A total of 40 patients were included in the analysis. The good angiographic outcome was observed in 94.1% of patients in DT8 cohort with an average attempt of 1.2 compared to 78.3% with average attempts of 2.0 in other group. Single pass good recanalization (TICI 2b or 3) and single pass complete revascularisation (TICI3) was significantly higher in DT group compared to DT3-5 group (82.4% vs 43.5%, P=0.013 and 42.9% vs 8.7%, P=0.003 respectively). A favourable trend towards a reduced overall procedural time (34.59 vs 55.59 minutes) was observed, but was not statistically significant (p value 0.15) CONCLUSION: Mild prolongation of DT to 8 minutes improves revascularisation outcome with fewer attempts, possibly due to better clot-stent interaction. Copyright © 2017. Published by Elsevier Inc.

  9. Aqueous Solution Vessel Thermal Model Development II

    Energy Technology Data Exchange (ETDEWEB)

    Buechler, Cynthia Eileen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-10-28

    The work presented in this report is a continuation of the work described in the May 2015 report, “Aqueous Solution Vessel Thermal Model Development”. This computational fluid dynamics (CFD) model aims to predict the temperature and bubble volume fraction in an aqueous solution of uranium. These values affect the reactivity of the fissile solution, so it is important to be able to calculate them and determine their effects on the reaction. Part A of this report describes some of the parameter comparisons performed on the CFD model using Fluent. Part B describes the coupling of the Fluent model with a Monte-Carlo N-Particle (MCNP) neutron transport model. The fuel tank geometry is the same as it was in the May 2015 report, annular with a thickness-to-height ratio of 0.16. An accelerator-driven neutron source provides the excitation for the reaction, and internal and external water cooling channels remove the heat. The model used in this work incorporates the Eulerian multiphase model with lift, wall lubrication, turbulent dispersion and turbulence interaction. The buoyancy-driven flow is modeled using the Boussinesq approximation, and the flow turbulence is determined using the k-ω Shear-Stress-Transport (SST) model. The dispersed turbulence multiphase model is employed to capture the multiphase turbulence effects.

  10. Heparin pre-treatment in patients with ST-segment elevation myocardial infarction and the risk of intracoronary thrombus and total vessel occlusion. Insights from the TASTE trial.

    Science.gov (United States)

    Karlsson, Sofia; Andell, Pontus; Mohammad, Moman A; Koul, Sasha; Olivecrona, Göran K; James, Stefan K; Fröbert, Ole; Erlinge, David

    2017-08-01

    Pre-treatment with unfractionated heparin is common in ST-segment elevation myocardial infarction (STEMI) protocols, but the effect on intracoronary thrombus burden is unknown. We studied the effect of heparin pre-treatment on intracoronary thrombus burden and Thrombolysis in Myocardial Infarction (TIMI) flow prior to percutaneous coronary intervention in patients with STEMI. The Thrombus Aspiration in ST-Elevation Myocardial Infarction in Scandinavia (TASTE) trial angiographically assessed intracoronary thrombus burden and TIMI flow, prior to percutaneous coronary intervention, in patients with STEMI. In this observational sub-study, patients pre-treated with heparin were compared with patients not pre-treated with heparin. Primary end points were a visible intracoronary thrombus and total vessel occlusion prior to percutaneous coronary intervention. Secondary end points were in-hospital bleeding, in-hospital stroke and 30-day all-cause mortality. Heparin pre-treatment was administered in 2898 out of 7144 patients (41.0%). Patients pre-treated with heparin less often presented with an intracoronary thrombus (61.3% vs. 66.0%, ppre-treatment was independently associated with a reduced risk of intracoronary thrombus (odds ratio (OR) 0.73, 95% confidence interval (CI)=0.65-0.83) and total vessel occlusion (OR 0.64, 95% CI=0.56-0.73), prior to percutaneous coronary intervention. There were no significant differences in secondary end points of in-hospital bleeding (OR 0.84, 95% CI=0.55-1.27), in-hospital stroke (OR 1.17, 95% CI=0.48-2.82) or 30-day all-cause mortality (hazard ratio 0.88, 95% CI=0.60-1.30). Heparin pre-treatment was independently associated with a lower risk of intracoronary thrombus and total vessel occlusion before percutaneous coronary intervention in patients with STEMI, without evident safety concerns, in this large multi-centre observational study.

  11. Model Of Navigational Safety Of Fishing Vessels In Polish EEZ

    Directory of Open Access Journals (Sweden)

    Przywarty Marcin

    2014-06-01

    Full Text Available The paper presents the assumptions of a simulation model for assessing the navigational safety of fishing vessels. The model consist of submodels of merchant and fishing vessels traffic, submodel of external condition and submodel of accident consequences. Paper present also a results of simulation experiment which was carried out for Polish EEZ. Model takes into account all Polish fishing vessels operating in the Polish EEZ with length more than 15 meters and the merchant vessels traffic in South Baltic Sea area. As a results positions of simulated collisions of fishing and merchant vessels, positions and sizes of simulated bunker spills and the positions of losses of fishing equipment were achieved.

  12. Hydrogel based occlusion systems

    OpenAIRE

    Stam, F.A.; Jackson, N.; Dubruel, P.; Adesanya, K.; Embrechts, A.; Mendes, E.; Neves, H.P.; Herijgers, P.; Verbrugghe, Y.; Shacham, Y.; Engel, L; Krylov, V.

    2013-01-01

    A hydrogel based occlusion system, a method for occluding vessels, appendages or aneurysms, and a method for hydrogel synthesis are disclosed. The hydrogel based occlusion system includes a hydrogel having a shrunken and a swollen state and a delivery tool configured to deliver the hydrogel to a target occlusion location. The hydrogel is configured to permanently occlude the target occlusion location in the swollen state. The hydrogel may be an electro-activated hydrogel (EAH) which could be ...

  13. [Reproducibility and repeatability of the determination of occlusal plane on digital dental models].

    Science.gov (United States)

    Qin, Yi-fei; Xu, Tian-min

    2015-06-18

    To assess the repeatability(intraobserver comparison)and reproducibility(interobserver comparison)of two different methods for establishing the occlusal plane on digital dental models. With Angle's classification as a stratification factor,48 cases were randomly extracted from 806 ones which had integrated clinical data and had their orthodontic treatment from July 2004 to August 2008 in Department of Orthodontics ,Peking University School and Hospital of Stomatology.Post-treatment plaster casts of 48 cases were scanned by Roland LPX-1200 3D laser scanner to generate geometry data as research subjects.In a locally developed software package,one observer repeated 5 times at intervals of at least one week to localize prescriptive landmarks on each digital model to establish a group of functional occlusal planes and a group of anatomic occlusal planes, while 6 observers established two other groups of functional and anatomic occlusal planes independently.Standard deviations of dihedral angles of each group on each model were calculated and compared between the related groups.The models with the five largest standard deviations of each group were studied to explore possible factors that might influence the identification of the landmarks on the digital models. Significant difference of intraobserver variability was not detected between the functional occlusal plane and the anatomic occlusal plane (P>0.1), while that of interobserver variability was detected (P0.1), while the anatomic occlusal plane's variability of the intraobserver was significantly smaller than that of the interobserver (Pmodels,both the functional and the anatomic occlusal planes are suitable as a conference plane with equal repeatability. When several observers measure a large number of digital models,the functional occlusal plane is more reproducible than the anatomic occlusal plane ,but the difference is small.

  14. Task-Difficulty Homeostasis in Car Following Models: Experimental Validation Using Self-Paced Visual Occlusion

    National Research Council Canada - National Science Library

    Pekkanen, Jami; Lappi, Otto; Itkonen, Teemu H; Summala, Heikki

    2017-01-01

    ...) model, by dynamically changing driving parameters as function of driver capability. We examined assumptions of these models experimentally using a self-paced visual occlusion paradigm in a simulated car following task...

  15. Association between proximal internal carotid artery steno-occlusive disease and diffuse wall thickening in its petrous segment: a magnetic resonance vessel wall imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiaoyi; Li, Dongye [Capital Medical University and Beijing Institute for Brain Disorders, Center for Brain Disorders Research, Beijing (China); Tsinghua University School of Medicine, Center for Biomedical Imaging Research, Department of Biomedical Engineering, Beijing (China); Zhao, Huilin [Shanghai Jiao Tong University, Department of Radiology, Renji Hospital, School of Medicine, Shanghai (China); Chen, Zhensen; Qiao, Huiyu; He, Le; Li, Rui [Tsinghua University School of Medicine, Center for Biomedical Imaging Research, Department of Biomedical Engineering, Beijing (China); Cui, Yuanyuan [PLA General Hospital, Department of Radiology, Beijing (China); Zhou, Zechen [Philips Research China, Healthcare Department, Beijing (China); Yuan, Chun [Tsinghua University School of Medicine, Center for Biomedical Imaging Research, Department of Biomedical Engineering, Beijing (China); University of Washington, Department of Radiology, Seattle, WA (United States); Zhao, Xihai [Tsinghua University School of Medicine, Center for Biomedical Imaging Research, Department of Biomedical Engineering, Beijing (China); Beijing Institute for Brain Disorders, Center for Stroke, Beijing (China)

    2017-05-15

    Significant stenosis or occlusion in carotid arteries may lead to diffuse wall thickening (DWT) in the arterial wall of downstream. This study aimed to investigate the correlation between proximal internal carotid artery (ICA) steno-occlusive disease and DWT in ipsilateral petrous ICA. Symptomatic patients with atherosclerotic stenosis (>0%) in proximal ICA were recruited and underwent carotid MR vessel wall imaging. The 3D motion sensitized-driven equilibrium prepared rapid gradient-echo (3D-MERGE) was acquired for characterizing the wall thickness and longitudinal extent of the lesions in petrous ICA and the distance from proximal lesion to the petrous ICA. The stenosis degree in proximal ICA was measured on the time-of-flight (TOF) images. In total, 166 carotid arteries from 125 patients (mean age 61.0 ± 10.5 years, 99 males) were eligible for final analysis and 64 showed DWT in petrous ICAs. The prevalence of severe DWT in petrous ICA was 1.4%, 5.3%, 5.9%, and 80.4% in ipsilateral proximal ICAs with stenosis category of 1%-49%, 50%-69%, 70%-99%, and total occlusion, respectively. Proximal ICA stenosis was significantly correlated with the wall thickness in petrous ICA (r = 0.767, P < 0.001). Logistic regression analysis showed that proximal ICA stenosis was independently associated with DWT in ipsilateral petrous ICA (odds ratio (OR) = 2.459, 95% confidence interval (CI) 1.896-3.189, P < 0.001). Proximal ICA steno-occlusive disease is independently associated with DWT in ipsilateral petrous ICA. (orig.)

  16. [Virtual orientation of the lower and upper jaws model on the position of centric occlusion].

    Science.gov (United States)

    Cheng, Xiaosheng; Liao, Wenhe; Zhang, Xiang; Yu, Qing

    2007-12-01

    The rotation axis equation of the simple articulator is built by the cylinder feature identification, which facilitates the rotation transform of the lower jaw data. Then the collision points and areas on the position of centric occlusion are found to form two collision couples. The virtual orientation of the lower and upper jaws model is realized by collision detection of the collision couples. Consequently the occlusal relation between the lower and upper jaws is established. It sets a good basis for the virtual adjustment of edentulous occlusal surface. The jaw movement of opening and closing in the state of hinge axis is also simulated accordingly.

  17. Incidentally diagnosed Takayasu arteritis on thyroid ultrasonography showing prominent collateral vessels of thyroidal arteries and common carotid artery occlusion

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Se Jin; Kim, Eun Kyung [Dept. of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2014-10-15

    We report a case of middle-aged woman incidentally diagnosed with Takayasu arteritis during the ultrasonography of a thyroid gland nodule. Prominent collaterals of the thyroidal arteries and a thin common carotid artery with mural thickening and deficient intraluminal flow signals were initially depicted on the ultrasonography with color Doppler. Subsequent magnetic resonance angiography and computed tomography aortography confirmed the diagnosis with the imaging features of a bilateral long segment common carotid artery occlusion and segmental stenosis of the left subclavian artery in addition to the suggestive physical findings.

  18. Altered low frequency oscillations of cortical vessels in patients with cerebrovascular occlusive disease – a NIRS study

    DEFF Research Database (Denmark)

    Phillip, Dorte; Iversen, Helle K; Schytz, Henrik W

    2013-01-01

    patients with both symptomatic carotid occlusive disease and cerebral hypoperfusion in comparison to healthy controls. Each hemisphere was examined with two NIRS channels using a 3 cm source detector distance. Arterial blood pressure (ABP) was measured via a finger plethysmograph. Using transfer function......) is a non-invasive optical method to investigate regional changes in oxygenated (oxyHb) and deoxygenated hemoglobin (deoxyHb) in the outermost layers of the cerebral cortex. In the present study we examined oxyHb low frequency oscillations, believed to reflect cortical cerebral autoregulation, in 16...

  19. Emergent intracranial balloon angioplasty and bailout self-expandable stent placement in acute large vessel occlusion of the anterior circulation: Experience of a single institution

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Young Jin; Seo, Jung Hwa; Jeong, Hae Woong [Busan Paik Hospital, Inje University, Busan (Korea, Republic of)

    2017-06-15

    To evaluate the outcomes of angioplasty for recanalization after acute ischemic stroke (AIS). The study population was selected from 134 patients who underwent endovascular revascularization therapy (ERT) for AIS between October 2011 and May 2014. Of those 134 patients, 39 who underwent balloon angioplasty with or without stent insertion were included in this study. Balloon angioplasty was the primary treatment for nine patients and a rescue method for 30 patients. The revascularization rate at 7 days, procedure-related complications, and clinical outcomes at 3 months were analyzed. The occlusion sites were the middle cerebral artery (n = 26), intracranial internal carotid artery (n = 10), and middle cerebral artery branch (n = 3). Angioplasty achieved successful revascularization (Thrombolysis in Cerebral Ischemia grade 2b–3) in 76.9% of patients. Computed tomography angiography performed 7 days post-procedure revealed a maintained reperfusion in 82.8% of successful cases. Only two patients had symptomatic intracerebral hemorrhage. At the 3-month follow-up, 18 (48.6%) and 10 (27.0%) patients showed good and poor functional outcomes, respectively (modified Rankin Scale scores, 0–2 and 5–6). Emergent balloon angioplasty and bailout self-expandable stent placement may be safe and effective for achieving successful revascularization in acute large vessel occlusion of the anterior circulation. It could be a feasible rescue method as well as a primary method for ERT.

  20. Clinical Decision Support Model to Predict Occlusal Force in Bruxism Patients.

    Science.gov (United States)

    Thanathornwong, Bhornsawan; Suebnukarn, Siriwan

    2017-10-01

    The aim of this study was to develop a decision support model for the prediction of occlusal force from the size and color of articulating paper markings in bruxism patients. We used the information from the datasets of 30 bruxism patients in which digital measurements of the size and color of articulating paper markings (12-µm Hanel; Coltene/Whaledent GmbH, Langenau, Germany) on canine protected hard stabilization splints were measured in pixels (P) and in red (R), green (G), and blue (B) values using Adobe Photoshop software (Adobe Systems, San Jose, CA, USA). The occlusal force (F) was measured using T-Scan III (Tekscan Inc., South Boston, MA, USA). The multiple regression equation was applied to predict F from the P and RGB. Model evaluation was performed using the datasets from 10 new patients. The patient's occlusal force measured by T-Scan III was used as a 'gold standard' to compare with the occlusal force predicted by the multiple regression model. The results demonstrate that the correlation between the occlusal force and the pixels and RGB of the articulating paper markings was positive (F = 1.62×P + 0.07×R -0.08×G + 0.08×B + 4.74; R 2 = 0.34). There was a high degree of agreement between the occlusal force of the patient measured using T-Scan III and the occlusal force predicted by the model (kappa value = 0.82). The results obtained demonstrate that the multiple regression model can predict the occlusal force using the digital values for the size and color of the articulating paper markings in bruxism patients.

  1. A Vessel Active Contour Model for Vascular Segmentation

    Directory of Open Access Journals (Sweden)

    Yun Tian

    2014-01-01

    Full Text Available This paper proposes a vessel active contour model based on local intensity weighting and a vessel vector field. Firstly, the energy function we define is evaluated along the evolving curve instead of all image points, and the function value at each point on the curve is based on the interior and exterior weighted means in a local neighborhood of the point, which is good for dealing with the intensity inhomogeneity. Secondly, a vascular vector field derived from a vesselness measure is employed to guide the contour to evolve along the vessel central skeleton into thin and weak vessels. Thirdly, an automatic initialization method that makes the model converge rapidly is developed, and it avoids repeated trails in conventional local region active contour models. Finally, a speed-up strategy is implemented by labeling the steadily evolved points, and it avoids the repeated computation of these points in the subsequent iterations. Experiments using synthetic and real vessel images validate the proposed model. Comparisons with the localized active contour model, local binary fitting model, and vascular active contour model show that the proposed model is more accurate, efficient, and suitable for extraction of the vessel tree from different medical images.

  2. A model based method for retinal blood vessel detection

    NARCIS (Netherlands)

    Vermeer, K. A.; Vos, F. M.; Lemij, H. G.; Vossepoel, A. M.

    2004-01-01

    Retinal blood vessels are important structures in ophthalmological images. Many detection methods are available, but the results are not always satisfactory. In this paper, we present a novel model based method for blood vessel detection in retinal images. It is based on a Laplace and thresholding

  3. Hydrogel based occlusion systems

    NARCIS (Netherlands)

    Stam, F.A.; Jackson, N.; Dubruel, P.; Adesanya, K.; Embrechts, A.; Mendes, E.; Neves, H.P.; Herijgers, P.; Verbrugghe, Y.; Shacham, Y.; Engel, L.; Krylov, V.

    2013-01-01

    A hydrogel based occlusion system, a method for occluding vessels, appendages or aneurysms, and a method for hydrogel synthesis are disclosed. The hydrogel based occlusion system includes a hydrogel having a shrunken and a swollen state and a delivery tool configured to deliver the hydrogel to a

  4. A model for ultrasound contrast agent in a phantom vessel

    KAUST Repository

    Qamar, Adnan

    2014-02-01

    A theoretical framework to model the dynamics of Ultrasound Contrast Agent (UCA) inside a phantom vessel is presented. The model is derived from the reduced Navier-Stokes equation and is coupled with the evolving flow field solution inside the vessel by a similarity transformation approach. The results are computed, and compared with experiments available in literature, for the initial UCA radius of Ro=1.5 μm and 2 μm for the vessel diameter of D=12 μm and 200 μm with the acoustic parameters as utilized in the experiments. When compared to other models, better agreement on smaller vessel diameter is obtained with the proposed coupled model. The model also predicts, quite accurately, bubble fragmentation in terms of acoustic and geometric parameters. © 2014 IEEE.

  5. THE ROLE OF ECG IN LOCALIZING THE CULPRIT VESSEL OCCLUSION IN ACUTE ST SEGMENT ELEVATION MYOCARDICAL INFARCTION WITH ANGIOGRAPHIC CORRELATION

    OpenAIRE

    Markandeya Rao; Ravindra Kumar; Nanditha

    2015-01-01

    BACKGROUND & OBJECTIVES The Electrocardiogram remains a crucial tool in the identification and management of acute myocardial infarction. A detailed analysis of patterns of ST-segment elevation may influence decisions regarding the perfusion therapy. This study was undertaken to identify the culprit vessel from ECG in patients with acute ST elevation myocardial infarction and correlate with coronary angiogram. MATERIALS & METHODS This is a prospective study, condu...

  6. Modeling the microclimate inside a vessel in in vitro culture : vessel ...

    African Journals Online (AJOL)

    M

    Numerical simulations show that variations in vessel internal humidity was ... Keywords : Agar, in vitro culture, microclimate, modeling, transfer coefficient. ... determining the atmospheric conditions inside .... is a function of air speed was used. .... latent heat of evaporation, R the gas constant and .... mesoscale circulation.

  7. Early Detection of Complete Vascular Occlusion in a Pedicle Flap Model Using Quantitation Spectral Imaging

    Science.gov (United States)

    Pharaon, Michael R.; Scholz, Thomas; Bogdanoff, Scott; Cuccia, David; Durkin, Anthony J.; Hoyt, David B.; Evans, Gregory R. D.

    2012-01-01

    Background Vascular occlusion after tissue transfer is a devastating complication that can lead to complete flap loss. Spatial frequency domain imaging is a new, noncontact, noninvasive, wide-field imaging technology capable of quantifying oxygenated and deoxygenated hemoglobin levels, total hemoglobin, and tissue saturation. Methods Pedicled fasciocutaneous flaps on Wistar rats (400 to 500 g) were created and underwent continuous imaging using spatial frequency domain imaging before and after selective vascular occlusion. Three flap groups (control, selective arterial occlusion, and selective venous occlusion) and a fourth group composed of native skin between the flaps were measured. Results There were no statistically significant differences between the control flap group and the experimental flap groups before selective vascular occlusion: oxyhemoglobin (p = 0.2017), deoxyhemoglobin (p = 0.3145), total hemoglobin (p = 0.2718), and tissue saturation,(p = 0.0777). In the selective arterial occlusion flap group, percentage change in total hemoglobin was statistically different from that of the control flap group (p = 0.0218). The remaining parameters were not statistically different from those of the control flap: percentage change in oxyhemoglobin (p = 0.0888), percentage change in deoxyhemoglobin (p = 0.5198), and percentage change in tissue saturation (p = 0.4220). The selective venous occlusion flap group demonstrated changes statistically different compared with the control flap group: percentage change in oxyhemoglobin (p = 0.0029) and deoxyhemoglobin, total hemoglobin, and tissue saturation (p oxyhemoglobin, deoxyhemoglobin, total hemoglobin, and tissue saturation. Results presented here indicate that this can be used to quantify and detect physiologic changes that occur after arterial and venous occlusion in a rodent tissue transfer flap model. This portable, noncontact, noninvasive device may have a high clinical applicability in monitoring postoperative

  8. Early detection of complete vascular occlusion in a pedicle flap model using quantitative [corrected] spectral imaging.

    Science.gov (United States)

    Pharaon, Michael R; Scholz, Thomas; Bogdanoff, Scott; Cuccia, David; Durkin, Anthony J; Hoyt, David B; Evans, Gregory R D

    2010-12-01

    Vascular occlusion after tissue transfer is a devastating complication that can lead to complete flap loss. Spatial frequency domain imaging is a new, noncontact, noninvasive, wide-field imaging technology capable of quantifying oxygenated and deoxygenated hemoglobin levels, total hemoglobin, and tissue saturation. Pedicled fasciocutaneous flaps on Wistar rats (400 to 500 g) were created and underwent continuous imaging using spatial frequency domain imaging before and after selective vascular occlusion. Three flap groups (control, selective arterial occlusion, and selective venous occlusion) and a fourth group composed of native skin between the flaps were measured. There were no statistically significant differences between the control flap group and the experimental flap groups before selective vascular occlusion: oxyhemoglobin (p=0.2017), deoxyhemoglobin (p=0.3145), total hemoglobin (p=0.2718), and tissue saturation, (p=0.0777). In the selective arterial occlusion flap group, percentage change in total hemoglobin was statistically different from that of the control flap group (p=0.0218). The remaining parameters were not statistically different from those of the control flap: percentage change in oxyhemoglobin (p=0.0888), percentage change in deoxyhemoglobin (p=0.5198), and percentage change in tissue saturation (p=0.4220). The selective venous occlusion flap group demonstrated changes statistically different compared with the control flap group: percentage change in oxyhemoglobin (p=0.0029) and deoxyhemoglobin, total hemoglobin, and tissue saturation (poxyhemoglobin, deoxyhemoglobin, total hemoglobin, and tissue saturation. Results presented here indicate that this can be used to quantify and detect physiologic changes that occur after arterial and venous occlusion in a rodent tissue transfer flap model. This portable, noncontact, noninvasive device may have a high clinical applicability in monitoring postoperative patients.

  9. Comparative analysis of the development of collateral vessels in macular edema due to branch retinal vein occlusion following grid laser or ranibizumab treatment

    Directory of Open Access Journals (Sweden)

    Kokolaki AE

    2015-09-01

    Full Text Available Afroditi Eleni Kokolaki, Ilias Georgalas, Chryssanthi Koutsandrea, Athanasios Kotsolis, Maria Niskopoulou, Ioannis LadasDepartment of Ophthalmology, University of Athens, Athens, Greece Purpose: To evaluate the differences in the development of collateral vessels in patients with macular edema due to branch retinal vein occlusion (BRVO after treatment with either grid laser or ranibizumab (RNB.Methods: Comparative study including patients with macular edema due to acute BRVO and best-corrected visual acuity (BCVA between 20/40 and 20/200. The sample was divided into two groups according to the treatment applied: laser group, including eyes treated with Argon laser when retinal hemorrhages were sufficiently absorbed to perform the treatment, and RNB group,  including patients treated initially with one monthly intravitreal injection for a period of 3 months of RNB and more injections according to need thereafter.. Before treatment patients in both groups, received a complete ophthalmic examination, including BCVA, fundus examination, optical coherence tomography, fundus color photography, and fundus fluorescein angiography (FA. This same protocol of examination was repeated in every visit after treatment, except FA that was only repeated every 3 months. The detection of the collateral vessels was done by two experienced examiners based on the analysis of the early phase of the FA. If there was a discrepancy in their judgment, the criterion of a third examiner evaluating the FA was considered.Results: Mean baseline BCVA was 0.86±0.26 and 0.82±0.25 (logMAR [logarithm of the minimum angle of resolution] in the RNB and laser groups, respectively (P=0.83. At the end of the follow-up, mean BCVA was 0.38±0.18 and 0.64±0.33 (logMAR in the RNB and laser groups, respectively. The difference in the final BCVA between both groups was statistically significant (P=0.002. Collaterals developed in both groups; 66.67% of patients (14 out of 21

  10. Initial hospital management of patients with emergent large vessel occlusion (ELVO): report of the standards and guidelines committee of the Society of NeuroInterventional Surgery.

    Science.gov (United States)

    McTaggart, Ryan A; Ansari, Sameer A; Goyal, Mayank; Abruzzo, Todd A; Albani, Barb; Arthur, Adam J; Alexander, Michael J; Albuquerque, Felipe C; Baxter, Blaise; Bulsara, Ketan R; Chen, Michael; Almandoz, Josser E Delgado; Fraser, Justin F; Frei, Donald; Gandhi, Chirag D; Heck, Don V; Hetts, Steven W; Hussain, M Shazam; Kelly, Michael; Klucznik, Richard; Lee, Seon-Kyu; Leslie-Mawzi, Thabele; Meyers, Philip M; Prestigiacomo, Charles J; Pride, G Lee; Patsalides, Athos; Starke, Robert M; Sunenshine, Peter; Rasmussen, Peter A; Jayaraman, Mahesh V

    2017-03-01

    To summarize the current literature regarding the initial hospital management of patients with acute ischemic stroke (AIS) secondary to emergent large vessel occlusion (ELVO), and to offer recommendations designed to decrease the time to endovascular treatment (EVT) for appropriately selected patients with stroke. Using guidelines for evidenced-based medicine proposed by the Stroke Council of the American Heart Association, a critical review of all available medical literature supporting best initial medical management of patients with AIS secondary to ELVO was performed. The purpose was to identify processes of care that most expeditiously determine the eligibility of a patient with an acute stroke for interventions including intravenous fibrinolysis with recombinant tissue plasminogen activator (IV tPA) and EVT using mechanical embolectomy. This review identifies four elements that are required to achieve timely revascularization in ELVO. (1) In addition to non-contrast CT (NCCT) brain scan, CT angiography should be performed in all patients who meet an institutional threshold for clinical stroke severity. The use of any advanced imaging beyond NCCT should not delay the administration of IV tPA in eligible patients. (2) Activation of the neurointerventional team should occur as soon as possible, based on either confirmation of large vessel occlusion or a prespecified clinical severity threshold. (3) Additional imaging techniques, particularly those intended to physiologically select patients for EVT (CT perfusion and diffusion-perfusion mismatch imaging), may provide additional value, but should not delay EVT. (4) Routine use of general anesthesia during EVT procedures, should be avoided if possible. These workflow recommendations apply to both primary and comprehensive stroke centers and should be tailored to meet the needs of individual institutions. Patients with ELVO are at risk for severe neurologic morbidity and mortality. To achieve the best possible

  11. Evaluation of the Solitaire system in a canine arterial thromboembolic occlusion model: is it safe for the endothelium?

    Science.gov (United States)

    Park, Soonchan; Hwang, Seon Moon; Song, Joon Seon; Suh, Dae Chul; Lee, Deok Hee

    2013-12-01

    The Solitaire system has recently been increasingly used for acute stroke treatment in which the endothelial safety immediately after its use has not been evaluated. This study was performed to evaluate the endothelial status when using a Solitaire system in a canine arterial occlusion model. Thromboembolic occlusion of both internal maxillary arteries was achieved in five mongrel dogs. In each animal, the Solitaire system (ev3, Irvine, CA, USA) was used for primary thrombectomy on the right side and for temporary stenting on the left side. Efficacy was assessed by comparing the recanalization rates, and safety was assessed using angiographic and microscopic assessments. Endothelial injuries were evaluated with light microscopy (LM) and scanning electron microscopy (SEM). Successful revascularizations were observed following primary thrombectomy in all five animals (100%) and after temporary stenting in two (40%). There was no incidence of vasospasm or vessel perforation in either group. Distal migration of the clot occurred in two animals that underwent primary thrombectomy. Endothelial injury was seen after primary thrombectomy in two animals (40%) and after temporary stenting in one (20%). The lesions presented as defects of the internal elastic lamina on LM and denudation of the wavy endothelial surface on SEM. During mechanical thrombectomy, the Solitaire system can cause endothelial injury both in primary thrombectomy and temporary stenting. Primary thrombectomy is likely to have a higher recanalization rate with increased endothelial injury.

  12. Marine Vessel Models in Changing Operational Conditions - A Tutorial

    DEFF Research Database (Denmark)

    Perez, Tristan; Sørensen, Asgeir; Blanke, Mogens

    2006-01-01

    This tutorial paper provides an introduction, from a systems perspective, to the topic of ship motion dynamics of surface ships. It presents a classification of parametric models currently used for monitoring and control of marine vessels. These models are valid for certain vessel operational...... conditions (VOC). However, since marine systems operate in changing VOCs, there is a need to adapt the models. To date, there is no theory available to describe a general model valid across different VOCs due to the complexity of the hydrodynamic involved. It is believed that system identification could...

  13. Clinical Selection Strategies to Identify Ischemic Stroke Patients With Large Anterior Vessel Occlusion: Results From SITS-ISTR (Safe Implementation of Thrombolysis in Stroke International Stroke Thrombolysis Registry).

    Science.gov (United States)

    Scheitz, Jan F; Abdul-Rahim, Azmil H; MacIsaac, Rachael L; Cooray, Charith; Sucharew, Heidi; Kleindorfer, Dawn; Khatri, Pooja; Broderick, Joseph P; Audebert, Heinrich J; Ahmed, Niaz; Wahlgren, Nils; Endres, Matthias; Nolte, Christian H; Lees, Kennedy R

    2017-02-01

    The National Institutes of Health Stroke Scale (NIHSS) correlates with presence of large anterior vessel occlusion (LAVO). However, the application of the full NIHSS in the prehospital setting to select patients eligible for treatment with thrombectomy is limited. Therefore, we aimed to evaluate the prognostic value of simple clinical selection strategies. Data from the Safe Implementation of Thrombolysis in Stroke International Stroke Thrombolysis Registry (January 2012-May 2014) were analyzed retrospectively. Patients with complete breakdown of NIHSS scores and documented vessel status were included. We assessed the association of prehospital stroke scales and NIHSS symptom profiles with LAVO (internal carotid artery, carotid-terminus or M1-segment of the middle cerebral artery). Among 3505 patients, 23.6% (n=827) had LAVO. Pathological finding on the NIHSS item best gaze was strongly associated with LAVO (adjusted odds ratio 4.5, 95% confidence interval 3.8-5.3). All 3 face-arm-speech-time test (FAST) items identified LAVO with high sensitivity. Addition of the item gaze to the original FAST score (G-FAST) or high scores on other simplified stroke scales increased specificity. The NIHSS symptom profiles representing total anterior syndromes showed a 10-fold increased likelihood for LAVO compared with a nonspecific clinical profile. If compared with an NIHSS threshold of ≥6, the prehospital stroke scales performed similarly or even better without losing sensitivity. Simple modification of the face-arm-speech-time score or evaluating the NIHSS symptom profile may help to stratify patients' risk of LAVO and to identify individuals who deserve rapid transfer to comprehensive stroke centers. Prospective validation in the prehospital setting is required. © 2017 American Heart Association, Inc.

  14. Development of a middle cerebral artery occlusion model in the nonhuman primate and a safety study of i.v. infusion of human mesenchymal stem cells.

    Directory of Open Access Journals (Sweden)

    Masanori Sasaki

    Full Text Available BACKGROUND: Most experimental stroke research is carried out in rodents, but given differences between rodents and human, nonhuman primate (NHP models may provide a valuable tool to study therapeutic interventions. The authors developed a surgical method for transient occlusion of the M1 branch of middle cerebral artery (MCA in the African green monkey to evaluate safety aspects of intravenous infusion of mesenchymal stem cells (hMSCs derived from human bone marrow. METHODS: The left Sylvian fissure was exposed by a small fronto-temporal craniotomy. The M1 branch of the MCA was exposed by microsurgical dissection and clipped for 2 to 4 hours. Neurological examinations and magnetic resonance imaging (MRI were carried out at regular post-operative course. hMSCs were infused 1 hour after reperfusion (clip release in the 3-hour occlusion model. RESULTS: During M1 occlusion, two patterns of changes were observed in the lateral hemisphere surface. One pattern (Pattern 1 was darkening of venous blood, small vessel collapse, and blood pooling with no venous return in cortical veins. Animals with these three features had severe and lasting hemiplegia and MRI demonstrated extensive MCA territory infarction. Animals in the second pattern (Pattern 2 displayed darkening of venous blood, small vessel collapse, and reduced but incompletely occluded venous flow and the functional deficit was much less severe and MRI indicated smaller infarction areas in brain. The severe group (Pattern 1 likely had less extensive collateral circulation than the less severe group (Pattern 2 where venous pooling of blood was not observed. The hMSC infused animals showed a trend for greater functional improvement that was not statistically significant in the acute phase and no additive negative effects. CONCLUSIONS: These results indicate inter-animal variability of collateral circulation after complete M1 occlusion and that hMSC infusion is safe in the developed NHP stroke model.

  15. Evaluation of histological changes after tracheal occlusion at different gestational ages in a fetal rat model

    Directory of Open Access Journals (Sweden)

    Rodrigo Melo Gallindo

    2013-01-01

    Full Text Available OBJECTIVES: To evaluate the histological changes of tracheal cartilage and epithelium caused by tracheal occlusion at different gestational ages in a fetal rat model. METHODS: Rat fetuses were divided into two groups: a External control, composed of non-operated rats, and b Interventional group, composed of rats operated upon on gestational day 18.5 (term = 22 days, divided into triads: 1 Tracheal occlusion, 2 Internal control and 3 Sham (manipulated but not operated. Morphological data for body weight, total lung weight and total lung weight/body weight ratio were collected and measured on gestational days 19.5, 20.5 and 21.5. Tracheal samples were histologically processed, and epithelial, chondral and total tracheal thicknesses were measured on each gestational day. RESULTS: The tracheal occlusion group exhibited an increase in total lung weight/body weight ratio (p<0.001. Histologically, this group had a thicker epithelial thickness (p<0.05 and thinner chondral (p<0.05 and total tracheal thicknesses (p<0.001. These differences were more prominent on gestational days 20.5 and 21.5. CONCLUSION: Tracheal occlusion changed tracheal morphology, increased epithelial thickness and considerably decreased total tracheal thickness. These changes in the tracheal wall could explain the development of tracheomegaly, recently reported in some human fetuses subjected to tracheal occlusion.

  16. RANKL, Osteopontin, and Osteoclast Homeostasis in a Hyper-Occlusion Mouse Model

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Cameron G.; Ito, Yoshihiro; Dangaria, Smit; Luan, Xianghong; Diekwisch, Thomas G.H. (UIC)

    2010-11-15

    The biological mechanisms that maintain the position of teeth in their sockets establish a dynamic equilibrium between bone resorption and apposition. In order to reveal some of the dynamics involved in the tissue responses towards occlusal forces on periodontal ligament (PDL) and alveolar bone homeostasis, we developed the first mouse model of hyperocclusion. Swiss-Webster mice were kept in hyperocclusion for 0, 3, 6, and 9 d. Morphological and histological changes in the periodontium were assessed using micro-computed tomography (micro-CT) and ground sections with fluorescent detection of vital dye labels. Sections were stained for tartrate-resistant acid phosphatase, and the expression of receptor activator of nuclear factor-{kappa}B ligand (RANKL) and osteopontin (OPN) was analyzed by immunohistochemistry and real-time polymerase chain reaction (PCR). Traumatic occlusion resulted in enamel surface abrasion, inhibition of alveolar bone apposition, significant formation of osteoclasts at 3, 6 and 9 d, and upregulation of OPN and RANKL. Data from this study suggest that both OPN and RANKL contribute to the stimulation of bone resorption in the hyperocclusive state. In addition, we propose that the inhibition of alveolar bone apposition by occlusal forces is an important mechanism for the control of occlusal height that might work in synergy with RANKL-induced bone resorption to maintain normal occlusion.

  17. Comprehensive Analysis of Chicken Vessels as Microvascular Anastomosis Training Model

    Directory of Open Access Journals (Sweden)

    Bo Young Kang

    2017-01-01

    Full Text Available BackgroundNonliving chickens are commonly used as a microvascular anastomosis training model. However, previous studies have investigated only a few types of vessel, and no study has compared the characteristics of the various vessels. The present study evaluated the anatomic characteristics of various chicken vessels as a training model.MethodsEight vessels—the brachial artery, basilic vein, radial artery, ulnar artery, ischiatic artery and vein, cranial tibial artery, and common dorsal metatarsal artery—were evaluated in 26 fresh chickens and 30 chicken feet for external diameter (ED and thicknesses of the tunica adventitia and media. The dissection time from skin incision to application of vessel clamps was also measured.ResultsThe EDs of the vessels varied. The ischiatic vein had the largest ED of 2.69±0.33 mm, followed by the basilic vein (1.88±0.36 mm, ischiatic artery (1.68±0.24 mm, common dorsal metatarsal artery (1.23±0.23 mm, cranial tibial artery (1.18±0.19 mm, brachial artery (1.08±0.15 mm, ulnar artery (0.82±0.13 mm, and radial artery (0.56±0.12 mm, and the order of size was consistent across all subjects. Thicknesses of the tunica adventitia and media were also diverse, ranging from 74.09±19.91 µm to 158.66±40.25 µm (adventitia and from 31.2±7.13 µm to 154.15±46.48 µm (media, respectively. Mean dissection time was <3 minutes for all vessels.ConclusionsOur results suggest that nonliving chickens can provide various vessels with different anatomic characteristics, which can allow trainees the choice of an appropriate microvascular anastomosis training model depending on their purpose and skillfulness.

  18. Spatial modeling of occlusion patterns applied to the detection of surface-laid mines

    Science.gov (United States)

    Lundberg, Magnus P.; Brown, Christopher L.; Uppsall, Magnus S.

    2004-09-01

    Images recorded in ground areas potentially containing surface laid land mines are considered. The first hypothesis is that the image is of clutter (grass) only, while the alternative is that the image contains a partially occluded (covered) land mine in addition to the clutter. In such a scenario, the occlusion pattern is unknown and has to be treated as a nuisance parameter. In a previous paper it was shown that deterministic treatment of the unknown occlusion pattern, in companion with the applied model, renders a substantial increase in detector performance as compared to employment of the traditional additive model. However, a deterministic assumption ignores possible correlation and additional gains could be possible by taking the spatial properties into account. In order to incorporate knowledge regarding the occlusion, the spatial distribution is characterized in terms of an underlying Markov Random Field (MRF) model. A major concern with MRF models is their complexity. Therefore, in addition to this, a less computationally demanding technique to accommodate the occlusion behavior is also proposed. The main purpose of this paper is to investigate if significant gains are possible by acknowledging the spatial dependence. Evaluation on data using real occluded targets however indicates that the gain seem to be marginal.

  19. Assessment of collateral artery function and growth in a pig model of stepwise coronary occlusion

    NARCIS (Netherlands)

    de Groot, Daphne; Grundmann, Sebastian; Timmers, Leo; Pasterkamp, Gerard; Hoefer, Imo E.

    de Groot D, Grundmann S, Timmers L, Pasterkamp G, Hoefer IE. Assessment of collateral artery function and growth in a pig model of stepwise coronary occlusion. Am J Physiol Heart Circ Physiol 300: H408-H414, 2011. First published October 15, 2010; doi: 10.1152/ajpheart.00070.2010.-Therapeutic

  20. The Effect of Infrarenal Aortic Balloon Occlusion on Weaning from Supraceliac Aortic Balloon Occlusion in a Porcine Model (Sus scrofa) of Hemorrhagic Shock

    Science.gov (United States)

    2017-06-15

    all animals , and continued for six hours. Half of the animals were randomly assigned to Zone-3 REBOA for an additional 45 minutes following Zone-1...concentration or resuscitation requirements.Conclusion: In an animal model of hemorrhagic shock and Zone-1 REBOA, subsequent Zone-3 aortic occlusion did not add

  1. Blood vessel modeling for interactive simulation of interventional neuroradiology procedures.

    Science.gov (United States)

    Kerrien, E; Yureidini, A; Dequidt, J; Duriez, C; Anxionnat, R; Cotin, S

    2017-01-01

    Endovascular interventions can benefit from interactive simulation in their training phase but also during pre-operative and intra-operative phases if simulation scenarios are based on patient data. A key feature in this context is the ability to extract, from patient images, models of blood vessels that impede neither the realism nor the performance of simulation. This paper addresses both the segmentation and reconstruction of the vasculature from 3D Rotational Angiography data, and adapted to simulation: An original tracking algorithm is proposed to segment the vessel tree while filtering points extracted at the vessel surface in the vicinity of each point on the centerline; then an automatic procedure is described to reconstruct each local unstructured point set as a skeleton-based implicit surface (blobby model). The output of successively applying both algorithms is a new model of vasculature as a tree of local implicit models. The segmentation algorithm is compared with Multiple Hypothesis Testing (MHT) algorithm (Friman et al., 2010) on patient data, showing its greater ability to track blood vessels. The reconstruction algorithm is evaluated on both synthetic and patient data and demonstrate its ability to fit points with a subvoxel precision. Various tests are also reported where our model is used to simulate catheter navigation in interventional neuroradiology. An excellent realism, and much lower computational costs are reported when compared to triangular mesh surface models. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Task-Difficulty Homeostasis in Car Following Models: Experimental Validation Using Self-Paced Visual Occlusion.

    Science.gov (United States)

    Pekkanen, Jami; Lappi, Otto; Itkonen, Teemu H; Summala, Heikki

    2017-01-01

    Car following (CF) models used in traffic engineering are often criticized for not incorporating "human factors" well known to affect driving. Some recent work has addressed this by augmenting the CF models with the Task-Capability Interface (TCI) model, by dynamically changing driving parameters as function of driver capability. We examined assumptions of these models experimentally using a self-paced visual occlusion paradigm in a simulated car following task. The results show strong, approximately one-to-one, correspondence between occlusion duration and increase in time headway. The correspondence was found between subjects and within subjects, on aggregate and individual sample level. The long time scale aggregate results support TCI-CF models that assume a linear increase in time headway in response to increased distraction. The short time scale individual sample level results suggest that drivers also adapt their visual sampling in response to transient changes in time headway, a mechanism which isn't incorporated in the current models.

  3. Computer modelling of anterior circulation stroke: Proof of concept in Cerebrovascular Occlusion

    Directory of Open Access Journals (Sweden)

    THANH G PHAN

    2014-09-01

    Full Text Available Background: Current literature emphasizes the role of the Circle of Willis (CoW in salvaging ischemic brain tissue but not that of leptomeningeal anastomoses (LA. We developed a computational model of the cerebral circulation to 1 evaluate the roles of the CoW and LA in restoring flow to the superficial compartment of the middle cerebral artery territory and 2 estimate the size of the LA required to maintain flow above the critical ischemic threshold (>30% of baseline under simulated occlusion. Methods: Cerebral vasculature was modelled as a network of junctions connected by cylindrical pipes. The experiments included occlusion of successive distal branches of the intracranial arteries while the diameters of LA were varied. Results: The model showed that the region of reduced flow became progressively smaller as the site of occlusion was moved from the large proximal to the smaller distal arteries. There was no improvement in flow in the MCA territory when the diameters of the inter-territorial LA were varied from 0.0625 mm to 0.5 mm while keeping the intra-territorial LA constant. By contrast, the diameter of the inter-territorial LA needed to be greater than 1.0 mm in order to provide adequate (>30% flow to selected arteries in the occluded MCA territory. Conclusions: The CoW and inter-territorial LA together play important supportive roles in intracranial artery occlusion. Computational modelling provides the ability to experimentally investigate the effect of arterial occlusion on CoW and LA function.

  4. Detection of questionable occlusal carious lesions using an electrical bioimpedance method with fractional electrical model

    Energy Technology Data Exchange (ETDEWEB)

    Morais, A. P. [Biomedical Engineering Program, COPPE, Rio de Janeiro (Brazil); Salgado de Oliveira University, Marechal Deodoro Street, 217 – Centro, Niterói, Rio de Janeiro (Brazil); Pino, A. V. [Biomedical Engineering Program, COPPE, Rio de Janeiro (Brazil); Souza, M. N. [Biomedical Engineering Program, COPPE, Rio de Janeiro (Brazil); Electronics Department at Polytechnic School, Federal University of Rio de Janeiro, Centro de Tecnologia Bloco H sala 217, Ilha do Fundão, Rio de Janeiro (Brazil)

    2016-08-15

    This in vitro study evaluated the diagnostic performance of an alternative electric bioimpedance spectroscopy technique (BIS-STEP) detect questionable occlusal carious lesions. Six specialists carried out the visual (V), radiography (R), and combined (VR) exams of 57 sound or non-cavitated occlusal carious lesion teeth classifying the occlusal surfaces in sound surface (H), enamel caries (EC), and dentinal caries (DC). Measurements were based on the current response to a step voltage excitation (BIS-STEP). A fractional electrical model was used to predict the current response in the time domain and to estimate the model parameters: Rs and Rp (resistive parameters), and C and α (fractional parameters). Histological analysis showed caries prevalence of 33.3% being 15.8% hidden caries. Combined examination obtained the best traditional diagnostic results with specificity = 59.0%, sensitivity = 70.9%, and accuracy = 60.8%. There were statistically significant differences in bioimpedance parameters between the H and EC groups (p = 0.016) and between the H and DC groups (Rs, p = 0.006; Rp, p = 0.022, and α, p = 0.041). Using a suitable threshold for the Rs, we obtained specificity = 60.7%, sensitivity = 77.9%, accuracy = 73.2%, and 100% of detection for deep lesions. It can be concluded that BIS-STEP method could be an important tool to improve the detection and management of occlusal non-cavitated primary caries and pigmented sites.

  5. Modeling Self-Occlusions/Disocclusions in Dynamic Shape and Appearance Tracking for Obtaining Precise Shape

    KAUST Repository

    Yang, Yanchao

    2013-05-01

    We present a method to determine the precise shape of a dynamic object from video. This problem is fundamental to computer vision, and has a number of applications, for example, 3D video/cinema post-production, activity recognition and augmented reality. Current tracking algorithms that determine precise shape can be roughly divided into two categories: 1) Global statistics partitioning methods, where the shape of the object is determined by discriminating global image statistics, and 2) Joint shape and appearance matching methods, where a template of the object from the previous frame is matched to the next image. The former is limited in cases of complex object appearance and cluttered background, where global statistics cannot distinguish between the object and background. The latter is able to cope with complex appearance and a cluttered background, but is limited in cases of camera viewpoint change and object articulation, which induce self-occlusions and self-disocclusions of the object of interest. The purpose of this thesis is to model self-occlusion/disocclusion phenomena in a joint shape and appearance tracking framework. We derive a non-linear dynamic model of the object shape and appearance taking into account occlusion phenomena, which is then used to infer self-occlusions/disocclusions, shape and appearance of the object in a variational optimization framework. To ensure robustness to other unmodeled phenomena that are present in real-video sequences, the Kalman filter is used for appearance updating. Experiments show that our method, which incorporates the modeling of self-occlusion/disocclusion, increases the accuracy of shape estimation in situations of viewpoint change and articulation, and out-performs current state-of-the-art methods for shape tracking.

  6. Improved Wave-vessel Transfer Functions by Uncertainty Modelling

    DEFF Research Database (Denmark)

    Nielsen, Ulrik Dam; Fønss Bach, Kasper; Iseki, Toshio

    2016-01-01

    This paper deals with uncertainty modelling of wave-vessel transfer functions used to calculate or predict wave-induced responses of a ship in a seaway. Although transfer functions, in theory, can be calculated to exactly reflect the behaviour of the ship when exposed to waves, uncertainty in input...

  7. Numerical model study of radio frequency vessel sealing thermodynamics

    Science.gov (United States)

    Pearce, John

    2015-03-01

    Several clinically successful clinical radio frequency vessel-sealing devices are currently available. The dominant thermodynamic principles at work involve tissue water vaporization processes. It is necessary to thermally denature vessel collagen, elastin and their adherent proteins to achieve a successful fusion. Collagens denature at middle temperatures, between about 60 and 90 C depending on heating time and rate. Elastin, and its adherent proteins, are more thermally robust, and require temperatures in excess of the boiling point of water at atmospheric pressure to thermally fuse. Rapid boiling at low apposition pressures leads to steam vacuole formation, brittle tissue remnants and frequently to substantial disruption in the vessel wall, particularly in high elastin-content arteries. High apposition pressures substantially increase the equilibrium boiling point of tissue water and are necessary to ensure a high probability of a successful seal. The FDM numerical models illustrate the beneficial effects of high apposition pressures.

  8. Models and Algorithms for Container Vessel Stowage Optimization

    DEFF Research Database (Denmark)

    Delgado-Ortegon, Alberto

    planning that includes features of stowage planning that have not been considered in previous work. For slot planning, a fast and accurate representative model to optimally stow vessel sections is introduced. The second SP approach serves as the optimization component of a commercial decision support tool...... used for interactive planning of container vessels. Expert's know-how formulated as user preferences is integrated into the heuristic optimization component and used to tackle complex constraints and optimize combinatorial objectives. According to our experimental evaluation, stowage plans computed...... by our heuristic are competitive enough with respect to those made by experts under the same conditions. The CCP evaluates how the stowage characteristics of containers with different features affect important performance measures used in liner shipping companies, e.g., vessel intake and cargo revenue...

  9. Correlation of angina pectoris and perfusion decrease by collateral circulation in single-vessel coronary chronic total occlusion using myocardial perfusion single-photon emssion computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Sang Geon; Park, Ki Seong; Kang, Sae Ryung [Chonnam National University Hospital, Gwangju (Korea, Republic of); and others

    2016-03-15

    To evaluate the perfusion decrease in donor myocardium by collateral circulation and its correlation with angina pectoris in patients with chronic total occlusion (CTO) using myocardial perfusion single-photon emission computed tomography (MPS). Thirty-six patients with single-vessel CTO without any other stenosis were included. All patients underwent MPS and coronary angiography (CAG) within 2 months. Total 72 donor arteries were evaluated for the grades of collaterals to the CTO artery using the Rentrop grading system on CAG. Perfusion defects and perfusion scores in donor and CTO territories were analyzed on MPS. Myocardial perfusion of donor and CTO territories were evaluated according to the presence of angina pectoris and the grades of collateral circulation. When the CTO territory was ischemic, symptomatic patients showed higher summed difference scores in the CTO territory compared to asymptomatic patients (3.5 ± 2.4 vs. 1.5 ± 0.8 for symptomatic and asymptomatic groups respectively; p = 0.034). However, when the CTO territory was nonischemic, symptomatic patients showed higher summed stress scores (SSS, 4.3 ± 2.9 vs. 1.6 ± 1.2; p = 0.032) and summed rest scores (SRS, 4.2 ± 2.5 vs. 1.5 ± 1.1; p = 0.003) in the donor territories. On the per-vessel analysis, perfusion defects in donor territories were more frequent (0 % vs. 53 % vs. 86 % for Rentrop 0, Rentrop 1–2 and Rentrop 3, respectively; p < 0.001) and showed higher SSS (0.0 ± 0.0, 1.3 ± 1.6 and 2.1 ± 1.1 for Rentrop 0, Rentrop 1–2 and Rentrop 3, respectively; p = 0.001) and SRS (0.0 ± 0.0, 1.0 ± 1.4 and 1.7 ± 1.2; p = 0.003) at higher Rentrop grades, but their patterns were variable. Angina pectoris was related to either ischemia of the myocardium beyond CTO or a perfusion decrease in the donor myocardium. The perfusion decrease in donor myocardium positively correlated with the collateral grades.

  10. Endovascular Mechanical Thrombectomy in Large-Vessel Occlusion Ischemic Stroke Presenting with Low National Institutes of Health Stroke Scale: Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Griessenauer, Christoph J; Medin, Caroline; Maingard, Julian; Chandra, Ronil V; Ng, Wyatt; Brooks, Duncan Mark; Asadi, Hamed; Killer-Oberpfalzer, Monika; Schirmer, Clemens M; Moore, Justin M; Ogilvy, Christopher S; Thomas, Ajith J; Phan, Kevin

    2018-02-01

    Mechanical thrombectomy has become the standard of care for management of most large vessel occlusion (LVO) strokes. When patients with LVO present with minor stroke symptomatology, no consensus on the role of mechanical thrombectomy exists. A systematic review and meta-analysis were performed to identify studies that focused on mechanical thrombectomy, either as a standalone treatment or with intravenous tissue plasminogen activator (IV tPA), in patients with mild strokes with LVO, defined as a baseline National Institutes of Health Stroke Scale score ≤5 at presentation. Data on methodology, quality criteria, and outcome measures were extracted, and outcomes were compared using odds ratio as a summary statistic. Five studies met the selection criteria and were included. When compared with medical therapy without IV tPA, mechanical thrombectomy and medical therapy with IV tPA were associated with improved 90-day modified Rankin Scale (mRS) score. Among medical patients who were not eligible for IV tPA, those who underwent mechanical thrombectomy were more likely to experience good 90-day mRS than those who were not. There was no significant difference in functional outcome between mechanical thrombectomy and medical therapy with IV tPA, and no treatment subgroup was associated with intracranial hemorrhage or death. In patients with mild strokes due to LVO, mechanical thrombectomy and medical therapy with IV tPA led to better 90-day functional outcome. Mechanical thrombectomy plays an important role in the management of these patients, particularly in those not eligible for IV tPA. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Vessel Patency at 24 Hours and Its Relationship With Clinical Outcomes and Infarct Volume in REVASCAT Trial (Randomized Trial of Revascularization With Solitaire FR Device Versus Best Medical Therapy in the Treatment of Acute Stroke Due to Anterior Circulation Large Vessel Occlusion Presenting Within Eight Hours of Symptom Onset).

    Science.gov (United States)

    Millán, Mònica; Remollo, Sebastià; Quesada, Helena; Renú, Arturo; Tomasello, Alejandro; Minhas, Priyanka; Pérez de la Ossa, Natalia; Rubiera, Marta; Llull, Laura; Cardona, Pedro; Al-Ajlan, Fahad; Hernández, María; Assis, Zarina; Demchuk, Andrew M; Jovin, Tudor; Dávalos, Antoni

    2017-04-01

    Higher rates of target vessel patency at 24 hours were noted in the thrombectomy group compared with control group in recent randomized trials. As a prespecified secondary end point, we aimed to assess 24-hour revascularization rates by treatment groups and occlusion site as they related to clinical outcome and 24-hour infarct volume in REVASCAT (Randomized Trial of Revascularization With Solitaire FR Device Versus Best Medical Therapy in the Treatment of Acute Stroke Due to Anterior Circulation Large Vessel Occlusion Presenting Within Eight Hours of Symptom Onset). Independent core laboratory adjudicated vessel status according to modified arterial occlusive lesion classification at 24 hours on computed tomographic/magnetic resonance (94.2%/5.8%) angiography and 24-hour infarct volume on computed tomography were studied (95/103 patients in the thrombectomy group versus 94/103 in the control group, respectively). Complete revascularization was defined as modified arterial occlusive lesion grade 3. Its effect on clinical outcome was analyzed by ordinal logistic regression. Complete revascularization was achieved in 70.5% of the solitaire group and in 22.3% of the control group (Prevascularization rates were found for terminus internal carotid artery, M1, and tandem occlusions (all Prevascularization was associated with improved outcome in both thrombectomy (adjusted odds ratio, 4.5; 95% confidence interval, 1.9-10.9) and control groups (adjusted odds ratio, 2.7; 95% confidence interval, 1.0-6.7). Revascularization (modified arterial occlusive lesion grade 2/3) was associated with smaller infarct volumes in either treatment arm. Complete revascularization at 24 hours is a powerful predictor of favorable clinical outcome, whereas revascularization of any type results in reduced infarct volume in both thrombectomy and control groups. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01692379. © 2017 American Heart Association, Inc.

  12. Conditions of microvessel occlusion for blood coagulation in flow.

    Science.gov (United States)

    Bouchnita, A; Galochkina, T; Kurbatova, P; Nony, P; Volpert, V

    2017-09-01

    Vessel occlusion is a perturbation of blood flow inside a blood vessel because of the fibrin clot formation. As a result, blood circulation in the vessel can be slowed down or even stopped. This can provoke the risk of cardiovascular events. In order to explore this phenomenon, we used a previously developed mathematical model of blood clotting to describe the concentrations of blood factors with a reaction-diffusion system of equations. The Navier-Stokes equations were used to model blood flow, and we treated the clot as a porous medium. We identify the conditions of partial or complete occlusion in a small vessel depending on various physical and physiological parameters. In particular, we were interested in the conditions on blood flow and diameter of the wounded area. The existence of a critical flow velocity separating the regimes of partial and complete occlusion was demonstrated through the mathematical investigation of a simplified model of thrombin wave propagation in Poiseuille flow. We observed different regimes of vessel occlusion depending on the model parameters both for the numerical simulations and in the theoretical study. Then, we compared the rate of clot growth in flow obtained in the simulations with experimental data. Both of them showed the existence of different regimes of clot growth depending on the velocity of blood flow. Copyright © 2016 John Wiley & Sons, Ltd.

  13. Lack of acute cardioprotective effect from preischaemic erythropoietin administration in a porcine coronary occlusion model

    DEFF Research Database (Denmark)

    Kristensen, Jens; Mæng, Michael; Rehling, Michael

    2005-01-01

    to the early window and EPO2 pigs to the early and late window of ischaemic preconditioning in a closed chest, catheter-based, porcine coronary occlusion model (45 min of occlusion of the left anterior descending artery). Infarct size as a proportion of the ischaemic area (IS/AAR) was measured in vivo...... (mean+/-SD for C: 0.64+/-0.20; EPO1: 0.75+/-0.17; EPO2: 0.80+/-0.07). In the EPO2 group mean arterial pulmonary pressure and dP/dtmax were increased compared with control group. CONCLUSION: Despite promising results from studies in rodents, rhEPO did not reduce infarct size measured after 2.5 h...... of reperfusion in our porcine model....

  14. Modeling Air Stripping of Ammonia in an Agitated Vessel

    Energy Technology Data Exchange (ETDEWEB)

    Kofi, Adu-Wusu; Martino, Christopher J.; Wilmarth, William R.; Bennett, William M.; Peters, Robert s.

    2005-11-29

    A model has been developed to predict the rate of removal of ammonia (NH{sub 3}) from solution in a sparged agitated vessel. The model is first-order with respect to liquid-phase concentration of NH{sub 3}. The rate constant for the first-order equation is a function of parameters related to the vessel/impeller characteristics, the air/liquid properties as well as the process conditions. However, the vessel/impeller characteristics, the air/liquid properties, and the process conditions reduce the rate constant dependence to only three parameters, namely, the air sparge rate, the liquid volume or batch size, and the Henry's law constant of NH{sub 3} for the liquid or solution. Thus, the rate of removal is not mass-transfer limited. High air sparge rates, high temperatures, and low liquid volumes or batch sizes increase the rate of removal of NH{sub 3} from solution. The Henry's law constant effect is somewhat reflected in the temperature since Henry's law constant increases with increasing temperature. Data obtained from actual air stripping operation agree fairly well with the model predictions.

  15. Modeling the microclimate inside a vessel in in vitro culture : vessel ...

    African Journals Online (AJOL)

    Numerical simulations show that variations in vessel internal humidity was sensitive to transfer coefficient, climatic conditions within the growth chamber, evaporation and condensation of water vapor on the walls of the vessel. The variations in water vapor pressure deficits (VPD) (low during the nyctiperiod and high during ...

  16. Nonlinear dynamic model for visual object tracking on Grassmann manifolds with partial occlusion handling.

    Science.gov (United States)

    Khan, Zulfiqar Hasan; Gu, Irene Yu-Hua

    2013-12-01

    This paper proposes a novel Bayesian online learning and tracking scheme for video objects on Grassmann manifolds. Although manifold visual object tracking is promising, large and fast nonplanar (or out-of-plane) pose changes and long-term partial occlusions of deformable objects in video remain a challenge that limits the tracking performance. The proposed method tackles these problems with the main novelties on: 1) online estimation of object appearances on Grassmann manifolds; 2) optimal criterion-based occlusion handling for online updating of object appearances; 3) a nonlinear dynamic model for both the appearance basis matrix and its velocity; and 4) Bayesian formulations, separately for the tracking process and the online learning process, that are realized by employing two particle filters: one is on the manifold for generating appearance particles and another on the linear space for generating affine box particles. Tracking and online updating are performed in an alternating fashion to mitigate the tracking drift. Experiments using the proposed tracker on videos captured by a single dynamic/static camera have shown robust tracking performance, particularly for scenarios when target objects contain significant nonplanar pose changes and long-term partial occlusions. Comparisons with eight existing state-of-the-art/most relevant manifold/nonmanifold trackers with evaluations have provided further support to the proposed scheme.

  17. Steel Containment Vessel Model Test: Results and Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Costello, J.F.; Hashimote, T.; Hessheimer, M.F.; Luk, V.K.

    1999-03-01

    A high pressure test of the steel containment vessel (SCV) model was conducted on December 11-12, 1996 at Sandia National Laboratories, Albuquerque, NM, USA. The test model is a mixed-scaled model (1:10 in geometry and 1:4 in shell thickness) of an improved Mark II boiling water reactor (BWR) containment. A concentric steel contact structure (CS), installed over the SCV model and separated at a nominally uniform distance from it, provided a simplified representation of a reactor shield building in the actual plant. The SCV model and contact structure were instrumented with strain gages and displacement transducers to record the deformation behavior of the SCV model during the high pressure test. This paper summarizes the conduct and the results of the high pressure test and discusses the posttest metallurgical evaluation results on specimens removed from the SCV model.

  18. Dynamic Modelling of Tooth Deformation Using Occlusal Kinematics and Finite Element Analysis.

    Directory of Open Access Journals (Sweden)

    Stefano Benazzi

    Full Text Available Dental biomechanics based on finite element (FE analysis is attracting enormous interest in dentistry, biology, anthropology and palaeontology. Nonetheless, several shortcomings in FE modeling exist, mainly due to unrealistic loading conditions. In this contribution we used kinematics information recorded in a virtual environment derived from occlusal contact detection between high resolution models of an upper and lower human first molar pair (M1 and M1, respectively to run a non-linear dynamic FE crash colliding test.MicroCT image data of a modern human skull were segmented to reconstruct digital models of the antagonistic right M1 and M1 and the dental supporting structures. We used the Occlusal Fingerprint Analyser software to reconstruct the individual occlusal pathway trajectory during the power stroke of the chewing cycle, which was applied in a FE simulation to guide the M1 3D-path for the crash colliding test.FE analysis results showed that the stress pattern changes considerably during the power stroke, demonstrating that knowledge about chewing kinematics in conjunction with a morphologically detailed FE model is crucial for understanding tooth form and function under physiological conditions.Results from such advanced dynamic approaches will be applicable to evaluate and avoid mechanical failure in prosthodontics/endodontic treatments, and to test material behavior for modern tooth restoration in dentistry. This approach will also allow us to improve our knowledge in chewing-related biomechanics for functional diagnosis and therapy, and it will help paleoanthropologists to illuminate dental adaptive processes and morphological modifications in human evolution.

  19. Study of the occlusion effect induced by an earplug: Numerical modelling and experimental validation

    Science.gov (United States)

    Brummund, Martin

    (IRSST) and the Ecole de technologie superieure (ETS) has been launched. The present study represents a part of this collaboration and aims at studying the occlusion effect of the system earplug - ear canal through the development of novel numerical models and experimental methods. (Abstract shortened by UMI.).

  20. Occlusal Caries

    DEFF Research Database (Denmark)

    Carvalho, JC; Dige, Irene; Machiulskiene, V

    2016-01-01

    The management of occlusal caries still remains a major challenge for researchers as well as for general practitioners. The present paper reviews and discusses the most up-to-date knowledge and evidence of the biological principles guiding diagnosis, risk assessment, and management of the caries...... process on occlusal surfaces. In addition, it considers the whole spectrum of the caries process on occlusal surfaces, ranging from the molecular ecology of occlusal biofilms to the management of deep occlusal caries lesions. Studies using molecular methods with focus on biofilms in relation to occlusal...... caries should explore the relationship between the function and the structural composition of these biofilms to understand the role of occlusal biofilms in caries development. State-of-the-art measures to evaluate risk for occlusal caries lesion activity, caries incidence, and progression should include...

  1. CFD Modeling of a Multiphase Gravity Separator Vessel

    KAUST Repository

    Narayan, Gautham

    2017-05-23

    The poster highlights a CFD study that incorporates a combined Eulerian multi-fluid multiphase and a Population Balance Model (PBM) to study the flow inside a typical multiphase gravity separator vessel (GSV) found in oil and gas industry. The simulations were performed using Ansys Fluent CFD package running on KAUST supercomputer, Shaheen. Also, a highlight of a scalability study is presented. The effect of I/O bottlenecks and using Hierarchical Data Format (HDF5) for collective and independent parallel reading of case file is presented. This work is an outcome of a research collaboration on an Aramco project on Shaheen.

  2. Preliminary results of steel containment vessel model test

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, T.; Komine, K.; Arai, S. [Nuclear Power Engineering Corp., Tokyo (Japan)] [and others

    1997-04-01

    A high pressure test of a mixed-scaled model (1:10 in geometry and 1:4 in shell thickness) of a steel containment vessel (SCV), representing an improved boiling water reactor (BWR) Mark II containment, was conducted on December 11-12, 1996 at Sandia National Laboratories. This paper describes the preliminary results of the high pressure test. In addition, the preliminary post-test measurement data and the preliminary comparison of test data with pretest analysis predictions are also presented.

  3. Preliminary results of steel containment vessel model test

    Energy Technology Data Exchange (ETDEWEB)

    Luk, V.K.; Hessheimer, M.F. [Sandia National Labs., Albuquerque, NM (United States); Matsumoto, T.; Komine, K.; Arai, S. [Nuclear Power Engineering Corp., Tokyo (Japan); Costello, J.F. [Nuclear Regulatory Commission, Washington, DC (United States)

    1998-04-01

    A high pressure test of a mixed-scaled model (1:10 in geometry and 1:4 in shell thickness) of a steel containment vessel (SCV), representing an improved boiling water reactor (BWR) Mark II containment, was conducted on December 11--12, 1996 at Sandia National Laboratories. This paper describes the preliminary results of the high pressure test. In addition, the preliminary post-test measurement data and the preliminary comparison of test data with pretest analysis predictions are also presented.

  4. Kinematic Models for Manoeuvring and Seakeeping of Marine Vessels

    Directory of Open Access Journals (Sweden)

    Tristan Perez

    2007-01-01

    Full Text Available The motion of marine vessels has traditionally been studied using two different approaches: manoeuvring and seakeeping. These two approaches use different reference frames and coordinate systems to describe the motion. This paper derives the kinematic models that characterize the transformation of motion variables (position, velocity, accelerations and forces between the different coordinate systems used in these theories. The derivations hereby presented are done in terms of the formalism adopted in robotics. The advantage of this formulation is the use of matrix notation and operations. As an application, the transformation of linear equations of motion used in seakeeping into body-fixed coordinates is considered for both zero and forward speed.

  5. Crystal Plasticity Model of Reactor Pressure Vessel Embrittlement in GRIZZLY

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Pritam [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Biner, Suleyman Bulent [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Zhang, Yongfeng [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Spencer, Benjamin Whiting [Idaho National Laboratory (INL), Idaho Falls, ID (United States)

    2015-07-01

    The integrity of reactor pressure vessels (RPVs) is of utmost importance to ensure safe operation of nuclear reactors under extended lifetime. Microstructure-scale models at various length and time scales, coupled concurrently or through homogenization methods, can play a crucial role in understanding and quantifying irradiation-induced defect production, growth and their influence on mechanical behavior of RPV steels. A multi-scale approach, involving atomistic, meso- and engineering-scale models, is currently being pursued within the GRIZZLY project to understand and quantify irradiation-induced embrittlement of RPV steels. Within this framework, a dislocation-density based crystal plasticity model has been developed in GRIZZLY that captures the effect of irradiation-induced defects on the flow stress behavior and is presented in this report. The present formulation accounts for the interaction between self-interstitial loops and matrix dislocations. The model predictions have been validated with experiments and dislocation dynamics simulation.

  6. A minimally-invasive closed chest myocardial occlusion-reperfusion model in rhesus monkeys (Macaca mulatta): monitoring by contrast-enhanced ultrasound imaging.

    Science.gov (United States)

    Contamin, Hugues; Rioufol, Gilles; Bettinger, Thierry; Helbert, Alexandre; Portier, Karine G; Lepage, Olivier M; Thomas, Regi; Broillet, Anne; Tranquart, François; Schneider, Michel

    2012-03-01

    Myocardial infarction is frequently developed in canine and porcine models but exceptionally in non-human primates. The aim of this study was to develop a minimally invasive myocardial ischemic/reperfusion model in the monkey intended to be combined with imaging techniques, in particular myocardial contrast echocardiography (MCE). A balloon-tipped catheter was advanced via the femoral artery into the left anterior descending artery (LAD) under fluoroscopic guidance in ten anaesthetized male rhesus monkeys (Macaca mulatta). The balloon was inflated to completely occlude the vessel. Coronary angiography (CA) was performed to control the reality of the LAD occlusion/reperfusion. The ischemia period was followed by 3-6 h of reperfusion. Myocardial perfusion was evaluated during ischemia and at reperfusion by MCE using a novel ultrasound contrast agent (BR38). Occlusion was successfully induced during 18-50 min in nine out of the ten evaluated monkeys. ST segment elevation indicated myocardial ischemia. MCE showed complete transmural arrest of myocardial blood flow during the ischemia period and no persistent microvascular perfusion defects during reperfusion. A minimally invasive closed-chest model was successfully developed for creating myocardial ischemia in the rhesus monkey (Macaca mulatta). This technique could have an important role in mimicking acute coronary syndrome under physiologically and ethically-acceptable conditions. MCE provides non-invasively information on myocardial perfusion status, information not available from CA.

  7. Endograft Limb Occlusion in EVAR

    DEFF Research Database (Denmark)

    Taudorf, M; Jensen, L P; Vogt, K C

    2014-01-01

    occlusions were recorded and compared with a defined control group. Three different indices were used to describe the tortuosity of the iliac vessels based on preoperative CTA: pelvic artery index of tortuosity (PAI), common iliac artery index of tortuosity (CAI), and a visual description of vessel......% at 3 years. Logistic regression showed that iliac artery tortuosity (DIS) (p = .001) and body mass index (p = .007) had a significant impact on graft patency. CONCLUSION: A tortuous vessel on the preoperative CTA is associated with an increased risk of limb occlusion after EVAR. Adjunctive stenting...

  8. Intra-arterial thrombolysis using rt-PA in patients with acute stroke due to vessel occlusion of anterior and/or posterior cerebral circulation

    Energy Technology Data Exchange (ETDEWEB)

    Tountopoulou, Argyro; Ahl, Bjoern; Weissenborn, Karin [Hannover Medical School, Department of Neurology and Clinical Neurophysiology, Hannover (Germany); Becker, Hartmut; Goetz, Friedrich [Hannover Medical School, Department of Neuroradiology, Hannover (Germany)

    2008-01-15

    The aim of our study was to evaluate the safety and efficacy of intra-arterial (IA) thrombolysis using recombinant tissue plasminogen activator (rt-PA) in patients with acute stroke due to occlusion in the anterior or posterior circulation. We retrospectively analyzed the clinical and radiological data of 88 consecutive patients with acute ischemic stroke who underwent emergency cerebral angiography for the purpose of subsequent IA thrombolysis. The neurological deficit on admission and discharge was graded using the National Institutes of Health Stroke Scale (NIHSS) score. Baseline computer tomography (CT) scans were examined for any signs indicative of cerebral ischemia. The angiographic findings were classified according to the Thrombolysis in Myocardial Infarction (TIMI) score for myocardial infarction. Follow-up CT scans were examined for hemorrhagic complication. Of the 88 patients who underwent IA thrombolysis, 63 presented with complete or partial arterial occlusion in the suspected perfusion area. In these 63 patients, the median NIHSS score dropped from 15 points on admission to 10 points at discharge. The recanalization rate was 52.6% for partial and complete reperfusion. In-hospital mortality was 20.6% (9.1% for carotid, 44.4% for basilar territory occlusion). Intracerebral bleeding (ICB) occurred in 38.6% of the patients with occlusion in the anterior circulation, resulting in these patients presenting a worse clinical outcome than those without ICB. Only minor extracranial bleedings occurred in 20.6% of patients. Patients with ICB had a significantly higher frequency of ischemic signs on the baseline CT scan. Occlusion of a cerebral artery is present in about 75% of the patients eligible for thrombolytic therapy. Intra-arterial thrombolysis using rt-PA in patients with acute ischemic stroke can achieve re-vascularization, although ICB remains the major risk factor affecting its efficacy. (orig.)

  9. Longitudinal visualization of vascular occlusion, reperfusion, and remodeling in a zebrafish model of retinal vascular leakage using OCT angiography

    Science.gov (United States)

    Spitz, Kathleen; Bozic, Ivan; Desai, Vineet; Rao, Gopikrishna M.; Pollock, Lana M.; Anand-Apte, Bela; Tao, Yuankai K.

    2017-02-01

    Diabetic retinopathy (DR) and age-related macular degeneration (AMD) are two of the leading causes of blindness and visual impairment in the world. Neovascularization results in severe vision loss in DR and AMD and, thus, there is an unmet need to identify mechanisms of pathogenesis and novel anti-angiogenic therapies. Zebrafish is a leading model organism for studying human disease pathogenesis, and the highly conserved drug activity between zebrafish and humans and their ability to readily absorb small molecules dissolved in water has benefited pharmaceutical discovery. Here, we use optical coherence tomography (OCT) and OCT angiography (OCT-A) to perform noninvasive, in vivo retinal imaging in a zebrafish model of vascular leakage. Zebrafish were treated with diethylaminobenzaldehyde (DEAB) to induce vascular leakage and imaged with OCT and OCT-A at six time points over two weeks: baseline one day before treatment and one, three, six, eight, and ten days post treatment. Longitudinal functional imaging showed significant vascular response immediately after DEAB treatment. Observed vascular changes included partial or complete vascular occlusion immediately after treatment and reperfusion during a two-week period. Increased vascular tortuosity several days post treatment indicated remodeling, and bifurcations and collateral vessel formation were also observed. In addition, significant treatment response variabilities were observed in the contralateral eye of the same animal. Anatomical and functional normalization was observed in most animals by ten days post treatment. These preliminary results motivate potential applications of OCT-A as a tool for studying pathogenesis and therapeutic screening in zebrafish models of retinal vascular disease.

  10. Long-term occlusal changes assessed by the American Board of Orthodontics' model grading system.

    Science.gov (United States)

    Aszkler, Robert M; Preston, Charles B; Saltaji, Humam; Tabbaa, Sawsan

    2014-02-01

    The purpose of this study was to assess the long-term posttreatment changes in all criteria of the American Board of Orthodontics' (ABO) model grading system. We used plaster models from patients' final and posttreatment records. Thirty patients treated by 1 orthodontist using 1 bracket prescription were selected. An initial discrepancy index for each subject was performed to determine the complexity of each case. The final models were then graded using the ABO's model grading system immediately at posttreatment and postretention. Statistical analysis was performed on the 8 criteria of the model grading system, including paired t tests and Pearson correlations. An alpha of 0.05 was considered statistically significant. The average length of time between the posttreatment and postretention records was 12.7 ± 4.4 years. It was shown that alignment and rotations worsened by postretention (P = 0.014), and a weak statistically significant correlation at posttreatment and postretention was found (0.44; P = 0.016). Both marginal ridges and occlusal contacts scored less well at posttreatment. These criteria showed a significant decrease in scores between posttreatment and postretention (P <0.001), but the correlations were not statistically significant. The average total score showed a significant decrease between posttreatment and postretention (P <0.001), partly because of the large decrease in the previous 2 criteria. Higher scores for occlusal contacts and marginal ridges were found at the end of treatment; however, those scores and the overall scores for the 30 subjects improved in the postretention phase. Copyright © 2014. Published by Mosby, Inc.

  11. An artificial blood vessel implanted three-dimensional microsystem for modeling transvascular migration of tumor cells.

    Science.gov (United States)

    Wang, Xue-Ying; Pei, Ying; Xie, Min; Jin, Zi-He; Xiao, Ya-Shi; Wang, Yang; Zhang, Li-Na; Li, Yan; Huang, Wei-Hua

    2015-02-21

    Reproducing a tumor microenvironment consisting of blood vessels and tumor cells for modeling tumor invasion in vitro is particularly challenging. Here, we report an artificial blood vessel implanted 3D microfluidic system for reproducing transvascular migration of tumor cells. The transparent, porous and elastic artificial blood vessels are obtained by constructing polysaccharide cellulose-based microtubes using a chitosan sacrificial template, and possess excellent cytocompatibility, permeability, and mechanical characteristics. The artificial blood vessels are then fully implanted into the collagen matrix to reconstruct the 3D microsystem for modeling transvascular migration of tumor cells. Well-defined simulated vascular lumens were obtained by proliferation of the human umbilical vein endothelial cells (HUVECs) lining the artificial blood vessels, which enables us to reproduce structures and functions of blood vessels and replicate various hemodynamic parameters. Based on this model, the adhesion and transvascular migration of tumor cells across the artificial blood vessel have been well reproduced.

  12. Three-dimensional finite element modeling of the human external ear: simulation study of the bone conduction occlusion effect.

    Science.gov (United States)

    Brummund, Martin K; Sgard, Franck; Petit, Yvan; Laville, Frédéric

    2014-03-01

    A linear three-dimensional (3D) elasto-acoustic finite element model was used to simulate the occlusion effect following mechanical vibration at the mastoid process. The ear canal and the surrounding soft and bony tissues were reconstructed using images of a female cadaver head (Visible Human Project(®)). The geometrical model was coupled to a 3D earplug model and imported into comsol Multiphysics (COMSOL(®), Sweden). The software was used to solve for the sound pressure at the eardrum. Finite element modeling of the human external ear and of the occlusion effect has several qualities that can complement existing measuring and modeling techniques. First, geometrically complex structures such as the external ear can be reconstructed. Second, various material behavioral laws and complex loading can be accounted for. Last, 3D analyses of external ear substructures are possible allowing for the computation of a broad range of acoustic indicators. The model simulates consistent occlusion effects (e.g., insertion depth variability). Comparison with an experimental dataset, kindly provided by Stenfelt and Reinfeldt [Int. J. Audiol. 46, 595-608 (2007)], further demonstrates the model's accuracy. Power balances were used to analyze occlusion effect differences obtained for a silicone earplug and to examine the increase in sound energy when the ear canal is occluded (e.g., high-pass filter removal).

  13. Occlusion effects, Part II

    DEFF Research Database (Denmark)

    Hansen, Mie Østergaard

    The present report studies the mechanism of the occlusion effect by means of literature studies, experiments and model estimates. A mathematical model of the occlusion effect is developed. The model includes the mechanical properties of the earmould and the airborne sound as well as the body...... conducted sound from own voice. These aspects are new in the sense that previous studies disregard the earmould mechanics and includes only one sound source placed in the ear canal....

  14. Computational fluid dynamics study of the end-side and sequential coronary artery bypass anastomoses in a native coronary occlusion model.

    Science.gov (United States)

    Matsuura, Kaoru; Jin, Wei Wei; Liu, Hao; Matsumiya, Goro

    2017-11-27

    The objective of this study was to evaluate the haemodynamic patterns in each anastomosis fashion using a computational fluid dynamic study in a native coronary occlusion model. Fluid dynamic computations were carried out with ANSYS CFX (ANSYS Inc., Canonsburg, PA, USA) software. The incision lengths for parallel and diamond anastomoses were fixed at 2 mm. Native vessels were set to be totally occluded. The diameter of both the native and graft vessels was set to be 2 mm. The inlet boundary condition was set by a sample of the transient time flow measurement which was measured intraoperatively. The diamond anastomosis was observed to reduce flow to the native outlet and increase flow to the bypass outlet; the opposite was observed in the parallel anastomosis. Total energy efficiency was higher in the diamond anastomosis than the parallel anastomosis. Wall shear stress was higher in the diamond anastomosis than in the parallel anastomosis; it was the highest at the top of the outlet. A high oscillatory shear index was observed at the bypass inlet in the parallel anastomosis and at the native inlet in the diamond anastomosis. The diamond sequential anastomosis would be an effective option for multiple sequential bypasses because of the better flow to the bypass outlet than with the parallel anastomosis. However, flow competition should be kept in mind while using the diamond anastomosis for moderately stenotic vessels because of worsened flow to the native outlet. Care should be taken to ensure that the fluid dynamics patterns are optimal and prevent future native and bypass vessel disease progression.

  15. MR findings of bowel ischemia with mesenteric vascular occlusion : comparison with pathologic findings in a cat model

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Mi Young [College of Medicine, Ewha Womans University, Seoul (Korea, Republic of); Suh, Jeong Soo; Suh, Chang Hae [College of Medicine, Inha University, Inchon (Korea, Republic of); Gong, Gyuugup; Lim, Tae Hwan [College of Medicine, Ulsan University, Ulsan (Korea, Republic of); Kim, Sang Tae; Lee, Jung Hee [Asan Institute for Life Sciences, Asan (Korea, Republic of)

    2000-02-01

    In order to determine the characteristic MR findings for the early diagnosis of bowel ischemia, we analysed the dynamic enhanced MR images of ischemic bowel induced by mesenteric vascular occlusion in a cat model, and compared the T1-and T2-weighted images (W1) of extracted bowel with the pathologic findings. According to the ischemic period, twelve cats were assigned to either the normal control group (no ischemic period, N=3D2), the acute ischemic group (ligation of mesenteric vessels for 3 hours, n=3D6) or the subacute ischemic group (ligation of mesenteric vessels for 10 hours, n=3D4). Under general anesthesia, laparotomy was performed. The ileal artery and vein were ligated, and a columnar surface coil was applied to the expected bowel ischemia. Using a 4.7 T MR scanner, contrast-enhanced T1W1 were obtained, after bolus injection of contrast media, at 10, 20, 30, 60, and 90 minutes. After formalin fixation of the extracted bowel, T1- and T2W1 were obtained, and the specimens were pathologically examined. MR signal intensity at each layer of the bowel wall was measured and compared with the histopathologic findings. On contrast enhanced MR images, the submucosal layer showed most intensive enhancement, followed-in decreasing order of signal intensity- by muscle and mucosa. Time to peak enhancement of bowel wall was 10-minutes in the normal control group, and 20 and 60 minutes in the acute and subacute bowel ischemia groups, respectively. On T1W1, no significant differences in signal intensity were observed between the ischemic group and the normal control group. On T2W1, the signal intensity of the submucosal layer of the acute ischemic group was significantly higher than that of the normal control or subacute ischemic group, and the signal intensity of the muscular layer of the ischemic group was significantly higher than that of the normal control group. Time to peak enhancement of bowel wall was a helpful criterion for assessment of the ischemic period

  16. Mechanism of vaso-occlusion in sickle cell anemia

    Science.gov (United States)

    Lei, Huan; Karniadakis, George

    2012-11-01

    Vaso-occlusion crisis is one of the key hallmark of sickle cell anemia. While early studies suggested that the crisis is caused by blockage of a single elongated cell, recent experimental investigations indicate that vaso-occlusion is a complex process triggered by adhesive interactions among different cell groups in multiple stages. Based on dissipative particle dynamics, a multi-scale model for the sickle red blood cells (SS-RBCs), accounting for diversity in both shapes and cell rigidities, is developed to investigate the mechanism of vaso-occlusion crisis. Using this model, the adhesive dynamics of single SS-RBC was investigated in arterioles. Simulation results indicate that the different cell groups (deformable SS2 RBCs, rigid SS4 RBCs, leukocytes, etc.) exhibit heterogeneous adhesive behavior due to the different cell morphologies and membrane rigidities. We further simulate the tube flow of SS-RBC suspensions with different cell fractions. The more adhesive SS2 cells interact with the vascular endothelium and further trap rigid SS4 cells, resulting in vaso-occlusion in vessels less than 15 μm . Under inflammation, adherent leukocytes may also trap SS4 cells, resulting in vaso-occlusion in even larger vessels. This work was supported by the NSF grant CBET-0852948 and the NIH grant R01HL094270.

  17. Modeling the tortuosity of retinal vessels: does caliber play a role?

    Science.gov (United States)

    Trucco, Emanuele; Azegrouz, Hind; Dhillon, Baljean

    2010-09-01

    The tortuosity of retinal blood vessels is a diagnostic parameter assessed by ophthalmologists on the basis of examples and experience; no quantitative model is specified in clinical practice. All quantitative measures proposed to date for automatic image analysis purposes are functions of the curvature of the vessel skeleton. We suggest in this paper that curvature may not be the only quantity involved in modeling tortuosity, and that vessel thickness, or caliber, may also play a role. To support this statement, we devise a novel measure of tortuosity, depending on both curvature and thickness, and test it with 200 vessels selected by our clinical author from the public digital retinal images for vessel extraction database. Results are in good accordance with clinical judgment. Comparative experiments show performance similar to or better than that of four measures reported in the literature. We conclude that there is reasonable evidence supporting the investigation of tortuosity models incorporating more measurements than just skeleton curvature, and specifically vessel caliber.

  18. A Computational Model of Peripheral Photocoagulation for the Prevention of Progressive Diabetic Capillary Occlusion

    Directory of Open Access Journals (Sweden)

    Thomas J. Gast

    2016-01-01

    Full Text Available We developed a computational model of the propagation of retinal ischemia in diabetic retinopathy and analyzed the consequences of various patterns and sizes of burns in peripheral retinal photocoagulation. The model addresses retinal ischemia as a phenomenon of adverse local feedback in which once a capillary is occluded there is an elevated probability of occlusion of adjacent capillaries resulting in enlarging areas of retinal ischemia as is commonly seen clinically. Retinal burns of different sizes and patterns, treated as local oxygen sources, are predicted to have different effects on the propagation of retinal ischemia. The patterns of retinal burns are optimized with regard to minimization of the sum of the photocoagulated retina and computer predicted ischemic retina. Our simulations show that certain patterns of retinal burns are effective at preventing the spatial spread of ischemia by creating oxygenated boundaries across which the ischemia does not propagate. This model makes no statement about current PRP treatment of avascular peripheral retina and notes that the usual spot sizes used in PRP will not prevent ischemic propagation in still vascularized retinal areas. The model seems to show that a properly patterned laser treatment of still vascularized peripheral retina may be able to prevent or at least constrain the propagation of diabetic retinal ischemia in those retinal areas with intact capillaries.

  19. Pretest Round Robin Analysis of 1:4-Scale Prestressed Concrete Containment Vessel Model

    Energy Technology Data Exchange (ETDEWEB)

    HESSHEIMER,MICHAEL F.; LUK,VINCENT K.; KLAMERUS,ERIC W.; SHIBATA,S.; MITSUGI,S.; COSTELLO,J.F.

    2000-12-18

    The purpose of the program is to investigate the response of representative scale models of nuclear containment to pressure loading beyond the design basis accident and to compare analytical predictions to measured behavior. This objective is accomplished by conducting static, pneumatic overpressurization tests of scale models at ambient temperature. This research program consists of testing two scale models: a steel containment vessel (SCV) model (tested in 1996) and a prestressed concrete containment vessel (PCCV) model, which is the subject of this paper.

  20. Realistic texture extraction for 3D face models robust to self-occlusion

    Science.gov (United States)

    Qu, Chengchao; Monari, Eduardo; Schuchert, Tobias; Beyerer, Jürgen

    2015-02-01

    In the context of face modeling, probably the most well-known approach to represent 3D faces is the 3D Morphable Model (3DMM). When 3DMM is fitted to a 2D image, the shape as well as the texture and illumination parameters are simultaneously estimated. However, if real facial texture is needed, texture extraction from the 2D image is necessary. This paper addresses the possible problems in texture extraction of a single image caused by self-occlusion. Unlike common approaches that leverage the symmetric property of the face by mirroring the visible facial part, which is sensitive to inhomogeneous illumination, this work first generates a virtual texture map for the skin area iteratively by averaging the color of neighbored vertices. Although this step creates unrealistic, overly smoothed texture, illumination stays constant between the real and virtual texture. In the second pass, the mirrored texture is gradually blended with the real or generated texture according to the visibility. This scheme ensures a gentle handling of illumination and yet yields realistic texture. Because the blending area only relates to non-informative area, main facial features still have unique appearance in different face halves. Evaluation results reveal realistic rendering in novel poses robust to challenging illumination conditions and small registration errors.

  1. Cytological Kinetics of Periodontal Ligament in an Experimental Occlusal Trauma Model

    Science.gov (United States)

    Takaya, Tatsuo; Mimura, Hiroaki; Matsuda, Saeka; Nakano, Keisuke; Tsujigiwa, Hidetsugu; Tomida, Mihoko; Okafuji, Norimasa; Fujii, Takeo; Kawakami, Toshiyuki

    2015-01-01

    Using a model of experimental occlusal trauma in mice, we investigated cytological kinetics of periodontal ligament by means of histopathological, immunohistochemical, and photographical analysis methods. Periodontal ligament cells at furcation areas of molar teeth in the experimental group on day 4 showed a proliferation tendency of periodontal ligament cells. The cells with a round-shaped nucleus deeply stained the hematoxylin and increased within the day 4 specimens. Ki67 positive nuclei showed a prominent increase in the group on days 4 and 7. Green Fluorescent Protein (GFP) positivity also revealed cell movement but was slightly slow compared to Ki67. It indicated that restoration of mechanism seemed conspicuous by osteoclasts and macrophages from bone-marrow-derived cells for the periodontal ligament at the furcation area. It was suggested that the remodeling of periodontal ligament with cell acceleration was evoked from the experiment for the group on day 4 and after day 7. Periodontal ligament at the furcation area of the molar teeth in this experimental model recovered using the cells in situ and the bone-marrow-derived cells. PMID:26180510

  2. Cytological Kinetics of Periodontal Ligament in an Experimental Occlusal Trauma Model.

    Science.gov (United States)

    Takaya, Tatsuo; Mimura, Hiroaki; Matsuda, Saeka; Nakano, Keisuke; Tsujigiwa, Hidetsugu; Tomida, Mihoko; Okafuji, Norimasa; Fujii, Takeo; Kawakami, Toshiyuki

    2015-01-01

    Using a model of experimental occlusal trauma in mice, we investigated cytological kinetics of periodontal ligament by means of histopathological, immunohistochemical, and photographical analysis methods. Periodontal ligament cells at furcation areas of molar teeth in the experimental group on day 4 showed a proliferation tendency of periodontal ligament cells. The cells with a round-shaped nucleus deeply stained the hematoxylin and increased within the day 4 specimens. Ki67 positive nuclei showed a prominent increase in the group on days 4 and 7. Green Fluorescent Protein (GFP) positivity also revealed cell movement but was slightly slow compared to Ki67. It indicated that restoration of mechanism seemed conspicuous by osteoclasts and macrophages from bone-marrow-derived cells for the periodontal ligament at the furcation area. It was suggested that the remodeling of periodontal ligament with cell acceleration was evoked from the experiment for the group on day 4 and after day 7. Periodontal ligament at the furcation area of the molar teeth in this experimental model recovered using the cells in situ and the bone-marrow-derived cells.

  3. Citrus sinensis leaf petiole and blade colonization by Xylella fastidiosa: details of xylem vessel occlusion Colonização de pecíolo e folha de Citrus sinensis por Xylella fastidiosa

    Directory of Open Access Journals (Sweden)

    Eduardo Alves

    2009-04-01

    Full Text Available Citrus variegated chlorosis (CVC, caused by Xylella fastidiosa, is an important disease of citrus in Brazil. X. fastidiosa is restricted to xylem vessels of plants and knowledge regarding xylem colonization is still limited. Our goal was to verify how this bacterium colonizes and spreads within xylem vessels of sweet orange Citrus sinensis cv. Pêra. Petioles and pieces of leaf blades from naturally infected plant exhibiting characteristic symptoms were prepared for light microscopy (LM, scanning electron microscopy (SEM, transmission electron microscopy (TEM and immunogold labeling (IGL. Petioles from healthy plants were used as control. IGL results, using an antibody against wall hemicelluloses, revealed that the pit membrane of vessels was altered. Bacterial cells were observed in the pit between adjacent vessels. Results support the contention that X. fastidiosa produces cellulases to reach adjacent vessels. SEM revealed that colonization of sweet orange started with X. fastidiosa cells attaching to the xylem wall, followed by an increase in the number of bacterial cells, the production of fibrous material, and finally vessel occlusion by biofilm composed of copious amounts of amorphous material, strands and cells. Phenolic materials, hyperplasia and hypertrophy were noticed in leaves with gummy material. Xylem vessels frequently contained an unknown needle-like, crystallized matter blocking the vessel.A clorose variegada dos citrus (CVC, causada por uma bactéria restrita ao xilema (Xylella fastidiosa, é uma importante doença de citros no Brasil, entretanto, pouco se sabe sobre a colonização dos vasos do xilema pela bactéria. O objetivo deste trabalho foi estudar como X. fastidiosa invade os vasos adjacentes do xilema e algumas das alterações expressas por plantas de laranja Pêra. Foram coletadas 15 amostras de pecíolos e áreas das folhas de plantas com sintomas característicos da doença, as quais foram preparadas para

  4. Visualization of simulated small vessels on computed tomography using a model-based iterative reconstruction technique.

    Science.gov (United States)

    Higaki, Toru; Tatsugami, Fuminari; Fujioka, Chikako; Sakane, Hiroaki; Nakamura, Yuko; Baba, Yasutaka; Iida, Makoto; Awai, Kazuo

    2017-08-01

    This article describes a quantitative evaluation of visualizing small vessels using several image reconstruction methods in computed tomography. Simulated vessels with diameters of 1-6 mm made by 3D printer was scanned using 320-row detector computed tomography (CT). Hybrid iterative reconstruction (hybrid IR) and model-based iterative reconstruction (MBIR) were performed for the image reconstruction.

  5. Visualization of simulated small vessels on computed tomography using a model-based iterative reconstruction technique

    OpenAIRE

    Toru Higaki; Fuminari Tatsugami; Chikako Fujioka; Hiroaki Sakane; Yuko Nakamura; Yasutaka Baba; Makoto Iida; Kazuo Awai

    2017-01-01

    This article describes a quantitative evaluation of visualizing small vessels using several image reconstruction methods in computed tomography. Simulated vessels with diameters of 1?6?mm made by 3D printer was scanned using 320-row detector computed tomography (CT). Hybrid iterative reconstruction (hybrid IR) and model-based iterative reconstruction (MBIR) were performed for the image reconstruction.

  6. Visualization of simulated small vessels on computed tomography using a model-based iterative reconstruction technique

    Directory of Open Access Journals (Sweden)

    Toru Higaki

    2017-08-01

    Full Text Available This article describes a quantitative evaluation of visualizing small vessels using several image reconstruction methods in computed tomography. Simulated vessels with diameters of 1–6 mm made by 3D printer was scanned using 320-row detector computed tomography (CT. Hybrid iterative reconstruction (hybrid IR and model-based iterative reconstruction (MBIR were performed for the image reconstruction.

  7. Mechanical Recanalization of Cerebral Artery Embolic Occlusion Using a Self-Expanding Stent: Experimental Analysis in Canine Model

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jin Woo; Kim, Snag Joon; Lee, Deok Hee; Suh, Dae Chul [Dept. of Radiology and Research Institute of Radiology, Asan Medical Center, Ulsan University College of Medicine, Seoul (Korea, Republic of)

    2011-07-15

    To evaluate the feasibility of a self-expanding stent for acute embolic occlusion, and recanalization mechanism by histologic examination. Five mongrel dogs were used as study subjects. Each vertebral artery was occluded, and a self-expanding stent was used for recanalization. We evaluated the technical success rate for the placement of the stent to the targeted vessel, the recanalization rate, and residual stenosis. We obtained two specimens of the stented vertebral arteries for histologic evaluation. One dog died of an unknown cause during the induction of anesthesia. In two dogs, only one side of the vertebral artery was used, whereas both vertebral arteries were used in the remaining dogs. A total of six vertebral arteries were successfully occluded. The technical success rate for stenting without complication was 66.7%. The immediate recanalization rate after stenting was 100%. The residual stenosis was 35.6 {+-} 18.6%. On microscopic examination, the stent concentrically displaced the clot and the clot was captured between the stent mesh and arterial wall. Self-expanding stents were effective in revascularizing the cerebrovascular embolic occlusion. The self-expanding stent seemed to achieve recanalization by pushing the clot to the arterial wall and capturing the clot between the stent mesh and arterial wall.

  8. Operational model for vessel traffic using optimal control and calibration

    NARCIS (Netherlands)

    Shu, Y.; Daamen, W.; Ligteringen, H.; Hoogendoorn, S.P.

    2015-01-01

    Due to the ever-increasing economic globalization, the scale of transportation through ports and waterways has increased sharply. As the capacity of maritime infrastructure in ports and inland waterways is limited, it is important to simulate vessel behavior to balance safety and capacity in

  9. Pioglitazone prevents corporal veno-occlusive dysfunction in a rat model of type 2 diabetes mellitus.

    Science.gov (United States)

    Kovanecz, Istvan; Ferrini, Monica G; Vernet, Dolores; Nolazco, Gaby; Rajfer, Jacob; Gonzalez-Cadavid, Nestor F

    2006-07-01

    To determine whether corporal veno-occlusive dysfunction (CVOD), corporal smooth muscle (SM) loss, fibrosis and oxidative stress occur in a rat model of type 2 diabetes, and whether these are counteracted by pioglitazone, as pioglitazone is vasculoprotective, and corporal SM is an extension of arterial SM. Male obese Zucker fa/fa rats were fed chow containing 0%, 0.001% or 0.02% pioglitazone for 2 or 5 months, using untreated lean Zucker and Fischer 344 rats as controls. Functional changes were determined by dynamic-infusion cavernosometry. Histological changes were assessed by histochemistry and immunohistochemistry followed by quantitative image analysis and/or quantitative Western blot. CVOD was detected at 4.5 months of diabetes, accompanied by a lower corporal SM/collagen ratio, and increases in collagen, collagen III/I ratio, apoptotic index, and systemic and tissue oxidative stress. In the short-term treatment, high-dose pioglitazone normalized glycaemia and ameliorated fibrosis and oxidative stress, but induced CVOD, whereas the effects with the low dose were not significant. However, low-dose pioglitazone for 5 months corrected all alterations. Type 2 diabetes in Zucker fa/fa rats was associated with penile corporal fibrosis, oxidative stress, and CVOD, which were ameliorated by long-term low-dose pioglitazone, suggesting that this drug might protect the SM, independently from its antidiabetic effect.

  10. Model surgery technique for Le Fort I osteotomy--alteration in occlusal plane associated with upward transposition of posterior maxilla.

    Science.gov (United States)

    Yosano, Akira; Yamamoto, Masae; Shouno, Takahiro; Shiiki, Sayaka; Hamase, Maki; Kasahara, Kiyohiro; Takaki, Takashi; Takano, Nobuo; Uchiyama, Takeshi; Shibahara, Takahiko

    2005-08-01

    It is difficult to translate analytical values into accurate model surgery by traditional methods, especially when moving the posterior maxilla. This is because cephalometric radiographic analysis generated information on movement of the posterior nasal spine (PNS) can not be recreated in model surgery. Therefore, we propose a method that accurately reflects such analysis and simulation of movement using Quick Ceph 2000 (Orthodontic Processing Corporation, USA). This will allow the enrichment of model surgery prior to actual surgery in cases where upward movement of the posterior maxilla is involved. All patients who participated in this study had skeletal mandibular prognathism characterized by a small occlusal plane angle in respect to the S-N plane. Cephalometric radiographs were taken and analyzed with the Quick Ceph 2000. Pre- and post-surgical evaluations were performed using Sassouni arc analysis and Ricketts analysis. Prior to transposition, we then prepared an anterior occlusal bite record on a model mounted on an articulator. This bite was then used as a reference when the molar parts were to be transposed upwards. The use of a occlusal bite permitted an accurate translation of the preoperative computer simulation into model surgery, thus facilitating favorable surgical results.

  11. Modelling of pressure increase protection system for the vacuum vessel of W7-X device

    Energy Technology Data Exchange (ETDEWEB)

    Kaliatka, Tadas, E-mail: tadas.kaliatka@lei.lt; Uspuras, Eugenijus; Kaliatka, Algirdas

    2016-11-01

    Highlights: • Two in-vessel LOCAs (partial and guillotine break of 40 mm diameter pipe of cooling system) for Wendelstein 7-X fusion device were analyzed. • The analysis of the processes in the cooling system, vacuum vessel and pressure increase protection system were performed using thermal-hydraulic RELAP5 Mod3.3 code. • The suitability of pressure increase protection system was assessed. - Abstract: In fusion devices, plasma is contained in a vacuum vessel. The vacuum vessel cannot withstand a pressure above atmospheric. Any damage of in-vessel components could lead to water ingress and may lead to pressure increase and possible damage of vacuum vessel. In order to avoid such undesirable consequences, the pressure increase protection system is designed. In this article, the processes occurring in the vacuum vessel and pressure increase protection system of W7-X device during LOCA (small and guillotine pipe break) event are analyzed. The model of W7-X cooling system, vacuum vessel and pressure increase protection system was developed using RELAP5 code. Numerical analysis of partial and guillotine break of 40 mm diameter pipe of cooling system was performed. Calculation results showed that burst disc of the pressure increase protection system does not open when the cross section area of partial break in the cooling system is smaller than 1 mm{sup 2}. During the guillotine break of cooling system, the burst disc opens, but pressure increase protection system is capable to prevent overpressure of the vacuum vessel.

  12. Establishing an experimental rat model of photodynamically-induced retinal vein occlusion using erythrosin B

    Directory of Open Access Journals (Sweden)

    Wei Chen

    2014-04-01

    Full Text Available AIM:To develop a reliable, reproducible rat model of retinal vein occlusion (RVO with a novel photosensitizer (erythrosin B and study the cellular responses in the retina.METHODS:Central and branch RVOs were created in adult male rats via photochemically-induced ischemia. Retinal changes were monitored via color fundus photography and fluorescein angiography at 1 and 3h, and 1, 4, 7, 14, and 21d after irradiation. Tissue slices were evaluated histopathologically. Retinal ganglion cell survival at different times after RVO induction was quantified by nuclear density count. Retinal thickness was also observed.RESULTS:For all rats in both the central and branch RVO groups, blood flow ceased immediately after laser irradiation and retinal edema was evident at one hour. The retinal detachment rate was 100% at 3h and developed into bullous retinal detachment within 24h. Retinal hemorrhages were not observed until 24h. Clearance of the occluded veins at 7d was observed by fluorescein angiography. Disease manifestation in the central RVO eyes was more severe than in the branch RVO group. A remarkable reduction in the ganglion cell count and retinal thickness was observed in the central RVO group by 21d, whereas moderate changes occurred in the branch RVO group.CONCLUSION: Rat RVO created by photochemically-induced ischemia using erythrosin B is a reproducible and reliable animal model for mimicking the key features of human RVO. However, considering the 100% rate of retinal detachment, this animal model is more suitable for studying RVO with chronic retinal detachment.

  13. Blood Vessel Normalization in the Hamster Oral Cancer Model for Experimental Cancer Therapy Studies

    Energy Technology Data Exchange (ETDEWEB)

    Ana J. Molinari; Romina F. Aromando; Maria E. Itoiz; Marcela A. Garabalino; Andrea Monti Hughes; Elisa M. Heber; Emiliano C. C. Pozzi; David W. Nigg; Veronica A. Trivillin; Amanda E. Schwint

    2012-07-01

    Normalization of tumor blood vessels improves drug and oxygen delivery to cancer cells. The aim of this study was to develop a technique to normalize blood vessels in the hamster cheek pouch model of oral cancer. Materials and Methods: Tumor-bearing hamsters were treated with thalidomide and were compared with controls. Results: Twenty eight hours after treatment with thalidomide, the blood vessels of premalignant tissue observable in vivo became narrower and less tortuous than those of controls; Evans Blue Dye extravasation in tumor was significantly reduced (indicating a reduction in aberrant tumor vascular hyperpermeability that compromises blood flow), and tumor blood vessel morphology in histological sections, labeled for Factor VIII, revealed a significant reduction in compressive forces. These findings indicated blood vessel normalization with a window of 48 h. Conclusion: The technique developed herein has rendered the hamster oral cancer model amenable to research, with the potential benefit of vascular normalization in head and neck cancer therapy.

  14. Estimation of retinal vessel caliber using model fitting and random forests

    Science.gov (United States)

    Araújo, Teresa; Mendonça, Ana Maria; Campilho, Aurélio

    2017-03-01

    Retinal vessel caliber changes are associated with several major diseases, such as diabetes and hypertension. These caliber changes can be evaluated using eye fundus images. However, the clinical assessment is tiresome and prone to errors, motivating the development of automatic methods. An automatic method based on vessel crosssection intensity profile model fitting for the estimation of vessel caliber in retinal images is herein proposed. First, vessels are segmented from the image, vessel centerlines are detected and individual segments are extracted and smoothed. Intensity profiles are extracted perpendicularly to the vessel, and the profile lengths are determined. Then, model fitting is applied to the smoothed profiles. A novel parametric model (DoG-L7) is used, consisting on a Difference-of-Gaussians multiplied by a line which is able to describe profile asymmetry. Finally, the parameters of the best-fit model are used for determining the vessel width through regression using ensembles of bagged regression trees with random sampling of the predictors (random forests). The method is evaluated on the REVIEW public dataset. A precision close to the observers is achieved, outperforming other state-of-the-art methods. The method is robust and reliable for width estimation in images with pathologies and artifacts, with performance independent of the range of diameters.

  15. Modeling Ultraviolet (UV) Light Emitting Diode (LED) Energy Propagation in Reactor Vessels

    Science.gov (United States)

    2014-03-27

    concern is through Advanced Oxidation Processes (AOP). One such process uses ultraviolet (UV) energy to decompose hydrogen peroxide ( H2O2 ) to create...MODELING ULTRAVIOLET (UV) LIGHT EMITTING DIODE (LED) ENERGY PROPAGATION IN REACTOR VESSELS THESIS...

  16. Congenital diaphragmatic hernia: endotracheal fluid phospholipidic profile following tracheal occlusion in an experimental model.

    Science.gov (United States)

    Pelizzo, Gloria; Mimmi, Maria Chiara; Peiro, Jose Luis; Marotta, Mario; Amoroso, Francesco; Fusillo, Mario; Carlini, Veronica; Calcaterra, Valeria

    2017-02-01

    To compare endotracheal fluid (EF) and amniotic fluid (AF) phospholipidic profile changes following tracheal occlusion (TO) in the congenital diaphragmatic hernia (CDH) fetal lamb model, in order to support the efficacy of TO on lung maturity. A diaphragmatic defect was induced at 70 days' gestation, TO was carried out at day 102 and cesarean section at 136 days' gestation. EF and AF samples, collected at delivery, were evaluated using mass spectrometry (the analysis focused on palmitoyloleoyl-phosphatidylcholine [POPC, PC(18:1/16:0)], dipalmitoyl-phosphatidylcholine [DPPC, PC(16:0/16:0)] and sphingomyelins [SMs]). The effects of CDH and TO were different on AF and EF. POPC levels were higher than DPPC levels in AF of healthy lambs. Following induction of the diaphragmatic malformation, an evident decrease in POPC was noted, while a substantial return to normal POPC levels and an increased DPPC peak were prompted by the TO. After CDH induction, a decrease in N-palmitoyl-D-sphingomyelin [SM(d18:1/16:0)] was revealed (P<0.01) and an increased peak in SMs in AF was prompted by the TO (P=0.05). While the most represented phosphatidylcholine (PC) species in EF of healthy lambs was DPPC, CDH induced a decrease in the DPPC peak and treatment with TO induced its partial recovery. SMs were detectable only in healthy EF samples. The phospholipid recovery profile following TO suggests the potential role of this therapy in restoring processes involved in surfactant-mediated lung maturation, even though other interactions involved in AF turnover should be considered. Moreover, these metabolites could be used as biomarkers of fetal pulmonary development.

  17. Mitomycin-Induced Pulmonary Veno-Occlusive Disease: Evidence From Human Disease and Animal Models.

    Science.gov (United States)

    Perros, Frédéric; Günther, Sven; Ranchoux, Benoit; Godinas, Laurent; Antigny, Fabrice; Chaumais, Marie-Camille; Dorfmüller, Peter; Hautefort, Aurélie; Raymond, Nicolas; Savale, Laurent; Jaïs, Xavier; Girerd, Barbara; Cottin, Vincent; Sitbon, Olivier; Simonneau, Gerald; Humbert, Marc; Montani, David

    2015-09-01

    Pulmonary veno-occlusive disease (PVOD) is an uncommon form of pulmonary hypertension characterized by the obstruction of small pulmonary veins and a dismal prognosis. PVOD may be sporadic or heritable because of biallelic mutations of the EIF2AK4 gene coding for GCN2. Isolated case reports suggest that chemotherapy may be a risk factor for PVOD. We reported on the clinical, functional, and hemodynamic characteristics and outcomes of 7 cases of PVOD induced by mitomycin-C (MMC) therapy from the French Pulmonary Hypertension Registry. All patients displayed squamous anal cancer and were treated with MMC alone or MMC plus 5-fluoruracil. The estimated annual incidence of PVOD in the French population that have anal cancer is 3.9 of 1000 patients, which is much higher than the incidence of PVOD in the general population (0.5/million per year). In rats, intraperitoneal administration of MMC induced PVOD, as demonstrated by pulmonary hypertension at right-heart catheterization at days 21 to 35 and major remodeling of small pulmonary veins associated with foci of intense microvascular endothelial-cell proliferation of the capillary bed. In rats, MMC administration was associated with dose-dependent depletion of pulmonary GCN2 content and decreased smad1/5/8 signaling. Amifostine prevented the development of MMC-induced PVOD in rats. MMC therapy is a potent inducer of PVOD in humans and rats. Amifostine prevents MMC-induced PVOD in rats and should be tested as a preventive therapy for MMC-induced PVOD in humans. MMC-induced PVOD in rats represents a unique model to test novel therapies in this devastating orphan disease. © 2015 American Heart Association, Inc.

  18. Structure analysis of a reactor pressure vessel by two- and three-dimensional models. [PWR

    Energy Technology Data Exchange (ETDEWEB)

    Sacher, H.; Mayr, M.

    1982-03-01

    This paper investigates the reactor pressure vessel of a 1300 MW pressurised water reactor. In order to determine the stresses and deformations of the vessel, two- and three-dimensional finite element models are used which represent the real structure with different degrees of accuracy. The results achieved by these different models are compared for the case of the transient called ''Start up of the nuclear power plant''. 5 refs.

  19. Computed tomography depiction of small pediatric vessels with model-based iterative reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Koc, Gonca; Courtier, Jesse L.; Phelps, Andrew; Marcovici, Peter A.; MacKenzie, John D. [UCSF Benioff Children' s Hospital, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States)

    2014-07-15

    Computed tomography (CT) is extremely important in characterizing blood vessel anatomy and vascular lesions in children. Recent advances in CT reconstruction technology hold promise for improved image quality and also reductions in radiation dose. This report evaluates potential improvements in image quality for the depiction of small pediatric vessels with model-based iterative reconstruction (Veo trademark), a technique developed to improve image quality and reduce noise. To evaluate Veo trademark as an improved method when compared to adaptive statistical iterative reconstruction (ASIR trademark) for the depiction of small vessels on pediatric CT. Seventeen patients (mean age: 3.4 years, range: 2 days to 10.0 years; 6 girls, 11 boys) underwent contrast-enhanced CT examinations of the chest and abdomen in this HIPAA compliant and institutional review board approved study. Raw data were reconstructed into separate image datasets using Veo trademark and ASIR trademark algorithms (GE Medical Systems, Milwaukee, WI). Four blinded radiologists subjectively evaluated image quality. The pulmonary, hepatic, splenic and renal arteries were evaluated for the length and number of branches depicted. Datasets were compared with parametric and non-parametric statistical tests. Readers stated a preference for Veo trademark over ASIR trademark images when subjectively evaluating image quality criteria for vessel definition, image noise and resolution of small anatomical structures. The mean image noise in the aorta and fat was significantly less for Veo trademark vs. ASIR trademark reconstructed images. Quantitative measurements of mean vessel lengths and number of branches vessels delineated were significantly different for Veo trademark and ASIR trademark images. Veo trademark consistently showed more of the vessel anatomy: longer vessel length and more branching vessels. When compared to the more established adaptive statistical iterative reconstruction algorithm, model

  20. The effects of intense pulsed light (IPL) on blood vessels investigated by mathematical modeling.

    Science.gov (United States)

    Bäumler, Wolfgang; Vural, Emre; Landthaler, Michael; Muzzi, Francesco; Shafirstein, Gal

    2007-02-01

    Intense pulsed light (IPL) sources have been successfully used for coagulation of blood vessels in clinical practice. However, the broadband emission of IPL hampers the clinical evaluation of optimal light parameters. We describe a mathematical model in order to visualize the thermal effects of IPL on skin vessels, which was not available, so far. One IPL spectrum was shifted towards the near infrared range (near IR shifted spectrum: NIRSS) and the other was heavily shifted toward the visible range (visible shifted spectrum: VSS). The broadband emission was separated in distinct wavelengths with the respective relative light intensity. For each wavelength, the light and heat diffusion equations were simultaneously solved with the finite element method. The thermal effects of all wavelengths at the given radiant exposure (15 or 30 J/cm2) were added and the temperature in the vessels of varying diameters (60, 150, 300, 500 microm) was calculated for the entire pulse duration of 30 milliseconds. VSS and NIRSS both provided homogeneous heating in the entire vessel. With the exception of the small vessels (60 microm), which showed only a moderate temperature increase, all vessels exhibited a temperature raise within the vessel sufficient for coagulation with each IPL parameter. The time interval for effective temperature raise in larger vessels (diameter >60 microm) was clearly shorter than the pulse duration. In most instances, the vessel temperature was higher for VSS when compared to NIRSS. We presented a mathematical model capable of calculating the photon distribution and the thermal effects of the broadband IPL emission within cutaneous blood vessels. (c) 2007 Wiley-Liss, Inc.

  1. Theoretical modelling of physiologically stretched vessel in magnetisable stent assisted magnetic drug targeting application

    Energy Technology Data Exchange (ETDEWEB)

    Mardinoglu, Adil [Telecommunications Software and Systems Group (TSSG), Waterford Institute of Technology, Waterford (Ireland); Cregg, P.J.; Murphy, Kieran [Materials Characterisation and Processing Group, SEAM Centre, Waterford Institute of Technology, Waterford (Ireland); Curtin, Maurice [Trinity Centre for Bioengineering, Trinity College, Dublin 2 (Ireland); Prina-Mello, Adriele, E-mail: prinamea@tcd.i [Trinity Centre for Bioengineering, Trinity College, Dublin 2 (Ireland); Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College, Dublin 2 (Ireland)

    2011-02-15

    The magnetisable stent assisted magnetic targeted drug delivery system in a physiologically stretched vessel is considered theoretically. The changes in the mechanical behaviour of the vessel are analysed under the influence of mechanical forces generated by blood pressure. In this 2D mathematical model a ferromagnetic, coiled wire stent is implanted to aid collection of magnetic drug carrier particles in an elastic tube, which has similar mechanical properties to the blood vessel. A cyclic mechanical force is applied to the elastic tube to mimic the mechanical stress and strain of both the stent and vessel while in the body due to pulsatile blood circulation. The magnetic dipole-dipole and hydrodynamic interactions for multiple particles are included and agglomeration of particles is also modelled. The resulting collection efficiency of the mathematical model shows that the system performance can decrease by as much as 10% due to the effects of the pulsatile blood circulation. - Research highlights: Theoretical modelling of magnetic drug targeting on a physiologically stretched stent-vessel system. Cyclic mechanical force applied to mimic the mechanical stress and strain of both stent and vessel. The magnetic dipole-dipole and hydrodynamic interactions for multiple particles is modelled. Collection efficiency of the mathematical model is calculated for different physiological blood flow and magnetic field strength.

  2. Composite Pressure Vessel Variability in Geometry and Filament Winding Model

    Science.gov (United States)

    Green, Steven J.; Greene, Nathanael J.

    2012-01-01

    Composite pressure vessels (CPVs) are used in a variety of applications ranging from carbon dioxide canisters for paintball guns to life support and pressurant storage on the International Space Station. With widespread use, it is important to be able to evaluate the effect of variability on structural performance. Data analysis was completed on CPVs to determine the amount of variation that occurs among the same type of CPV, and a filament winding routine was developed to facilitate study of the effect of manufacturing variation on structural response.

  3. Intracarotid Sodium Nitroprusside on Fifth Post Ischemic Stroke Day in Middle Cerebral Artery Occlusion Rat Model.

    Science.gov (United States)

    Tewari, Vinod Kumar; Bhosale, Vivek; Shukla, Rakesh; Gupta, Hari Kishan Das; Sheeba

    2017-08-01

    Ischemic stroke at later stages (>4.5 hour) have very few treatment options left. In those cases Nitric Oxide (NO) may provide promising results. NO is active in signaling pathways. Sodium Nitroprusside (SNP), a NO donor was tested earlier in rat Middle Cerebral Artery Occlusion (MCAO) model in early stages (5-60 minutes) and found useful but in delayed stroke cases (60-120 minutes) found useless. This was due to local inducible Nitric Oxide Synthase Enzyme (iNOS) and superoxide (causes destructive effect) formation which was skipped. To evaluate the effect of Intracarotid Sodium Nitroprusside (ICSNP) in MCAO rat model of ischemic stroke (I/R model) fifth post ischemic stroke day. A total of 24 Sprague Dawley rats, weighing 250 gm to 280 gm, at CDRI-Lucknow, India were used. Rats were divided in three groups. Group A (n=4) were taken as sham with standard procedure but without any injection on fifth day, Group B (n=8) as control with injection of saline on fifth day and Group C (n=12) received SNP at dose of 3 mcg/kg/minute given directly in internal carotid artery via External Carotid Artery (ECA) with a modified intraluminal stump technique as Ischemia/Reperfusion (I/R) in ipsilateral MCAO at intracarotid artery region as a single dose therapy on fifth day and then wound was closed. Waited for full recovery for two hours, then neurobehavioural assessment scores were noted. Thereafter, the brains were quickly removed and sliced at 2 mm intervals. Animals showing no sign of neurological deficit, were excluded from the study. Tested animals were compared with control animals for neurological deficit, percentage of infarction by 2,3,5-Triphenyl Tetrazolium Chloride (TTC) staining, nNOS expression and scores were summed up. The statistical analysis was done by Newman-Keuls test, Graph Pad prism (version.5.0) and pgroup (Group C) showed a good reduction in the cerebral infarction of 53.42% as compared to control (Group B). Group A mean change in Newman-Keuls test and

  4. Treating asphericity in fuel particle pressure vessel modeling

    Science.gov (United States)

    Miller, Gregory K.; Wadsworth, Derek C.

    1994-07-01

    The prototypical nuclear fuel of the New Production Modular High Temperature Gas-Cooled Reactor (NP-MHTGR) consists of spherical TRISO-coated particles suspended in graphite cylinders. The coating layers surrounding the fuel kernels in these particles consist of pyrolytic carbon layers and a silicon carbide layer. These coating layers act as a pressure vessel which retains fission product gases. In the operating conditions of the NP-MHTGR, a small percentage of these particles (pressure vessels) are expected to fail due to the pressure loading. The fuel particles of the NP-MHTGR deviate to some degree from a true spherical shape, which may have some effect on the failure percentages. A method is presented that treats the asphericity of the particles in predicting failure probabilities for particle samples. It utilizes a combination of finite element analysis and Monte Carlo sampling and is based on the Weibull statistical theory. The method is used here to assess the effects of asphericity in particles of two common geometric shapes, i.e. faceted particles and ellipsoidal particles. The method presented could be used to treat particle anomalies other than asphericity.

  5. Method for modelling cerebral blood vessels and their bifurcations using circular, homogeneous, generalised cylinders.

    Science.gov (United States)

    Flaaris, J J; Volden, M; Haase, J; Ostergaard, L R

    2004-03-01

    A method for automatic modelling of blood vessels and their bifurcations from 3D scans of the brain is presented. The method is a three-step procedure. First, a skeleton of the cerebral blood vessels is developed, and then the surfaces of the blood vessels are located using an active contour approach. The active contour approach uses circular homogeneous generalised cylinders (CHGCs) to model the thin, elongated blood vessels. Finally, a novel method for modelling the surfaces of the bifurcations in a vessel tree is presented. The method was tested on simulated data: a computed tomography angiography (CTA) and four magnetic resonance angiography (MRA) volumes. Furthermore, the method was tested on ten magnetic resonance images (MRIs) to demonstrate its robustness. The test on the simulated data indicated that the approach for the surface modelling of vessels had a mean radius error of less than 0.1 mm and a mean localisation error of 0.1 mm. Surface models evaluated by an expert in vascular neurosurgery were found to have a smooth appearance and generally agreed with the image data. The test on the MRI scans indicated that the method performed well in noisy environments.

  6. Photocoagulation of dermal blood vessels with multiple laser pulses in an in vivo microvascular model.

    Science.gov (United States)

    Jia, Wangcun; Tran, Nadia; Sun, Victor; Marinček, Marko; Majaron, Boris; Choi, Bernard; Nelson, J Stuart

    2012-02-01

    Current laser therapy of port wine stain (PWS) birthmarks with a single laser pulse (SLP) does not produce complete lesion removal in the majority of patients. To improve PWS therapeutic efficacy, we evaluated the performance of an approach based on multiple laser pulses (MLP) to enhance blood vessel photocoagulation. The hamster dorsal window chamber model was used. Radiant exposure (RE), pulse repetition rate (f(r)), total number of pulses (n(p)), and length of vessel irradiated were varied. Blood vessels in the window were irradiated with either SLP with RE of 4-7 J/cm(2) or MLP with RE per pulse of 1.4-5.0 J/cm(2), f(r) of 0.5-26.0 Hz, and n(p) of 2-5. The laser wavelength was 532 nm and pulse duration was 1 ms. Either a 2 mm vessel segment or entire vessel branch was irradiated. Digital photographs and laser speckle images of the window were recorded before and at specific time points after laser irradiation to monitor laser-induced blood vessel structural and functional changes, respectively. We found that: (1) for a SLP approach, the RE required to induce blood vessel photocoagulation was 7 J/cm(2) as compared to only 2 J/cm(2) per pulse for the MLP approach; (2) for MLP, two pulses at a repetition rate of 5 Hz and a RE of 3 J/cm(2) can induce photocoagulation of more than 80% of irradiated blood vessel; and (3) irradiation of a longer segment of blood vessel resulted in lower reperfusion rate. The MLP approach can induce blood vessel photocoagulation at much lower RE per pulse as compared to SLP. The 5 Hz f(r) and the need for two pulses are achievable with modern laser technology, which makes the MLP approach practical in the clinical management of PWS birthmarks. Copyright © 2012 Wiley Periodicals, Inc.

  7. Validation of ASTEC V2 models for the behaviour of corium in the vessel lower head

    Energy Technology Data Exchange (ETDEWEB)

    Carénini, L., E-mail: laure.carenini@irsn.fr; Fleurot, J.; Fichot, F.

    2014-06-01

    The paper is devoted to the presentation of validation cases carried out for the models describing the corium behaviour in the “lower plenum” of the reactor vessel implemented in the V2.0 version of the ASTEC integral code, jointly developed by IRSN (France) and GRS (Germany). In the ASTEC architecture, these models are grouped within the single ICARE module and they are all activated in typical accident scenarios. Therefore, it is important to check the validity of each individual model, as long as experiments are available for which a single physical process is involved. The results of ASTEC applications against the following experiments are presented: FARO (corium jet fragmentation), LIVE (heat transfer between a molten pool and the vessel), MASCA (separation and stratification of corium non miscible phases) and OLHF (mechanical failure of the vessel). Compared to the previous ASTEC V1.3 version, the validation matrix is extended. This work allows determining recommended values for some model parameters (e.g. debris particle size in the fragmentation model and criterion for debris bed liquefaction). Almost all the processes governing the corium behaviour, its thermal interaction with the vessel wall and the vessel failure are modelled in ASTEC and these models have been assessed individually with satisfactory results. The main uncertainties appear to be related to the calculation of transient evolutions.

  8. Comparison of Bite Registration Material Accuracy on in office Laser Scanned Digital Model Occlusion

    Science.gov (United States)

    2014-05-20

    primary disadvantage of alginate lies in its dimensional instability over time (White, Fallis, & Vandewalle, 2010). Alginate impressions lose water by...patient’s jaw 7     relation can be determined either in maximum intercuspation given by occlusal morphology or mandibular position related to...following criteria: 1. No movement of teeth or displacement of soft tissues 2. Verify the accuracy of the interocclusal record in the mouth 3. Fit the

  9. Aneurysmal remodeling in the circle of Willis after carotid occlusion in an experimental model.

    Science.gov (United States)

    Tutino, Vincent M; Mandelbaum, Max; Choi, Hoon; Pope, Liza C; Siddiqui, Adnan; Kolega, John; Meng, Hui

    2014-03-01

    Carotid occlusions are associated with de novo intracranial aneurysm formation in clinical case reports, but this phenomenon is not widely studied. We performed bilateral carotid ligation (n=9) in rabbits to simulate carotid occlusion, and sham surgery (n=3) for control. Upon euthanasia (n=3 at 5 days, n=6 at 6 months post ligation, and n=3 at 5 days after sham operation), vascular corrosion casts of the circle of Willis (CoW) were created. Using scanning electron microscopy, we quantified gross morphologic, macroscopic, and microscopic changes on the endocasts and compared findings with histologic data. At 5 days, CoW arteries of ligated animals increased caliber. The posterior communicating artery (PCom) increased length and tortuosity, and the ophthalmic artery (OA) origin presented preaneurysmal bulges. At 6 months, calibers were unchanged from 5 days, PComs further increased tortuosity while presenting segmental dilations, and the OA origin and basilar terminus presented preaneurysmal bulges. This exploratory study provides evidence that flow increase after carotid occlusion produces both compensatory arterial augmentation and pathologic remodeling such as tortuosity and saccular/fusiform aneurysm. Our findings may have considerable clinical implications, as these lesser-known consequences should be considered when managing patients with carotid artery disease or choosing carotid ligation as a therapeutic option.

  10. Modeling and Control for Dynamic Positioned Marine Vessels in Drifting Managed Sea Ice

    Directory of Open Access Journals (Sweden)

    Øyvind Kåre Kjerstad

    2014-10-01

    Full Text Available This paper presents a development framework for dynamic positioning control systems for marine vessels in managed ice. Due to the complexity of the vessel-ice and ice-ice interactions a configurable high fidelity numerical model simulating the vessel, the ice floes, the water, and the boundaries is applied. The numerical model is validated using experimental data and coupled with a control application incorporating sensor models, control systems, actuator models, and other external dynamics to form a closed loop development platform. The ice drift reversal is simulated by moving the positioning reference frame in an elliptic trajectory, rather than moving each individual ice floe. A control plant model is argued, and a control system for managed ice is proposed based on conventional open water design methods. A case study shows that dynamic positioning in managed ice is feasible for some moderate ice conditions.

  11. Pump function curve shape for a model lymphatic vessel.

    Science.gov (United States)

    Bertram, C D; Macaskill, C; Moore, J E

    2016-07-01

    The transport capacity of a contractile segment of lymphatic vessel is defined by its pump function curve relating mean flow-rate and adverse pressure difference. Numerous system characteristics affect curve shape and the magnitude of the generated flow-rates and pressures. Some cannot be varied experimentally, but their separate and interacting effects can be systematically revealed numerically. This paper explores variations in the rate of change of active tension and the form of the relation between active tension and muscle length, factors not known from experiment to functional precision. Whether the pump function curve bends toward or away from the origin depends partly on the curvature of the passive pressure-diameter relation near zero transmural pressure, but rather more on the form of the relation between active tension and muscle length. A pump function curve bending away from the origin defines a well-performing pump by maximum steady output power. This behaviour is favoured by a length/active-tension relationship which sustains tension at smaller lengths. Such a relationship also favours high peak mechanical efficiency, defined as output power divided by the input power obtained from the lymphangion diameter changes and active-tension time-course. The results highlight the need to pin down experimentally the form of the length/active-tension relationship. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

  12. Endoluminal occlusion devices: technology update

    Directory of Open Access Journals (Sweden)

    Zander T

    2014-12-01

    Full Text Available Tobias Zander,1 Samantha Medina,1 Guillermo Montes,1 Lourdes Nuñez-Atahualpa,1 Michel Valdes,1 Manuel Maynar1,2 1Endoluminal/Vascular Department, Hospiten Hospital Group, Santa Cruz de Tenerife, 2University of Las Palmas de Gran Canarias, Las Palmas, Canary Island, Spain Abstract: Endoluminal occlusion has been performed since the early beginning of interventional radiology. Over recent decades, major technological advances have improved the techniques used and different devices have been developed for changing conditions. Most of these occlusion devices have been implemented in the vascular territory. Early embolization materials included glass particles, hot contrast, paraffin, fibrin, and tissue fragments such as muscle fibers and blood clots; today, occlusion materials include metallic devices, particles, and liquid materials, which can be indicated for proximal or distal occlusion, high-flow and low-flow situations, and in large-caliber and small-caliber vessels, based on need. Technological progress has led to a decreased size of delivery catheters, and an increase in safety due to release systems that permit the withdrawing and replacement of embolization material. Furthermore, bioactive embolization materials have been developed to increase the efficacy of embolization or the biological effect of medication. Finally, materials have been modified for changing indications. Intravascular stents were initially developed to keep an artery open; however, by adding a covering membrane, these stents can be used to occlude the wall of a vessel or other endoluminal structures. This article gives an overview of the devices most utilized for occlusion of endoluminal structures, as well as their major purpose in the endovascular territory. Keywords: embolization, endovascular treatment, occlusion devices, hemorrhage, aneurysm, fistula

  13. Ex-Vessel Core Melt Modeling Comparison between MELTSPREAD-CORQUENCH and MELCOR 2.1

    Energy Technology Data Exchange (ETDEWEB)

    Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Farmer, Mitchell [Argonne National Lab. (ANL), Argonne, IL (United States); Francis, Matthew W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-03-01

    System-level code analyses by both United States and international researchers predict major core melting, bottom head failure, and corium-concrete interaction for Fukushima Daiichi Unit 1 (1F1). Although system codes such as MELCOR and MAAP are capable of capturing a wide range of accident phenomena, they currently do not contain detailed models for evaluating some ex-vessel core melt behavior. However, specialized codes containing more detailed modeling are available for melt spreading such as MELTSPREAD as well as long-term molten corium-concrete interaction (MCCI) and debris coolability such as CORQUENCH. In a preceding study, Enhanced Ex-Vessel Analysis for Fukushima Daiichi Unit 1: Melt Spreading and Core-Concrete Interaction Analyses with MELTSPREAD and CORQUENCH, the MELTSPREAD-CORQUENCH codes predicted the 1F1 core melt readily cooled in contrast to predictions by MELCOR. The user community has taken notice and is in the process of updating their systems codes; specifically MAAP and MELCOR, to improve and reduce conservatism in their ex-vessel core melt models. This report investigates why the MELCOR v2.1 code, compared to the MELTSPREAD and CORQUENCH 3.03 codes, yield differing predictions of ex-vessel melt progression. To accomplish this, the differences in the treatment of the ex-vessel melt with respect to melt spreading and long-term coolability are examined. The differences in modeling approaches are summarized, and a comparison of example code predictions is provided.

  14. Evaluation of dental and basal arch forms using cone-beam CT and 3D virtual models of normal occlusion.

    Science.gov (United States)

    Bayome, Mohamed; Park, Jae Hyun; Han, Seong Ho; Baek, Seung-Hak; Sameshima, Glenn T; Kook, Yoon-Ah

    2013-05-01

    OBIECTIVES: To evaluate the relationship between the mandibular dental and basal arches using CBCT, and to assess the correlation between basal arch dimensions derived from CBCT and 3-dimensional (3D) virtual models in a cohort sample exhibiting normal occlusions. The facial axis (FA) and root centre (RC) points of mandibular teeth were identified on 32 CBCT images. FA and WALA points were digitised on 3D models of 28 mandibular casts from the same sample. The relationships between dental and basal arch dimensions, and between the two basal depth dimensions derived from RC and WALA points were statistically assessed by Pearson's correlation. Strong correlations were found between dental and basal intercanine and intermolar arch widths. Also, the basal intercanine width showed a moderate correlation with dental intermolar width and depth. The basal intercanine and intermolar widths measured on 3D models showed moderate correlations with those measurements on CBCT, whereas the basal canine and molar depths showed no correlations. The dental and basal anterior and posterior arch widths were strongly correlated in normal occlusion. No correlations were found between the arch depths measured from WALA points and RC points. Hence, RC points may represent more useable landmarks compared to WALA points in the evaluation of basal arch forms. It is recommended that the relationship between the dental and basal arches is evaluated during treatment planning in order to improve arch co-ordination.

  15. Fallopian tube occlusion with a shape memory polymer device: evaluation in a rabbit model.

    Science.gov (United States)

    Tang, Shuai; Zhang, Chan-Yu; Huang, Mei-Na; Luo, Yan-Feng; Liang, Zhi-Qing

    2013-02-01

    The present study evaluates the feasibility of a shape memory polymer (SMP) device for fallopian tube occlusion in rabbits. The SMP contraceptive device is made of poly(dl-lactic acid)-based poly(urethane urea) SMP in the shape of a spiral cylinder that was 10 mm long and had a diameter of 2.6 mm. Using this device, bilateral transuterine fallopian tube occlusions were performed in 78 New Zealand white female rabbits. Forty-eight female rabbits (group 1) were chosen as the experimental group and were implanted with the SMP devices. The remaining 30 female rabbits (group 2) served as the control group, which only received an incision in the abdomen but no SMP device. Follow-up consisted of hysterosalpingography, histologic evaluation and contraceptive effect. In addition, the shape memory behavior and in vivo degradation characterization of the SMP device were observed in this study. Under heat (37 °C) stimulation, the temporary shape SMP device returned to its permanent shape within 60 s. The average weight loss percentage of SMP devices was 7.0% at 2 weeks and 72.5% at 12 weeks. The inflammatory reactions caused by SMP devices were aseptic and nonspecific at 2 and 12 weeks, respectively. The SMP device boundaries and the surrounding tissues were obscured by fiber hyperplasia in 11/12 tubes at 24 weeks. Hysterosalpingography showed an occluded fallopian tube of Group 1 in 6/6 rabbits at 12 weeks and 6/6 rabbits at 24 weeks. No pregnancy was found in all 18 rabbits of group 1 (contraceptive rate of 100%); all 20 rabbits in the control group were pregnant. Biodegradable and biocompatible SMP devices could provide reliable, instant and permanent tubal occlusion. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Polymer-based blood vessel models with micro-temperature sensors in EVE

    Science.gov (United States)

    Mizoshiri, Mizue; Ito, Yasuaki; Hayakawa, Takeshi; Maruyama, Hisataka; Sakurai, Junpei; Ikeda, Seiichi; Arai, Fumihito; Hata, Seiichi

    2017-04-01

    Cu-based micro-temperature sensors were directly fabricated on poly(dimethylsiloxane) (PDMS) blood vessel models in EVE using a combined process of spray coating and femtosecond laser reduction of CuO nanoparticles. CuO nanoparticle solution coated on a PDMS blood vessel model are thermally reduced and sintered by focused femtosecond laser pulses in atmosphere to write the sensors. After removing the non-irradiated CuO nanoparticles, Cu-based microtemperature sensors are formed. The sensors are thermistor-type ones whose temperature dependences of the resistance are used for measuring temperature inside the blood vessel model. This fabrication technique is useful for direct-writing of Cu-based microsensors and actuators on arbitrary nonplanar substrates.

  17. Structure analysis of a reactor pressure vessel by two and three-dimensional models

    Energy Technology Data Exchange (ETDEWEB)

    Sacher, H.; Mayr, M. (Technischer Ueberwachungs-Verein Bayern e.V., Muenchen (Germany, F.R.))

    1982-03-01

    This paper investigates the reactor pressure vessel of a 1300 MW pressurised water reactor. In order to determine the stresses and deformations of the vessel, two- and three-dimensional finite element models are used which represent the real structure with different degrees of accuracy. The results achieved by these different models are compared for the case of the transient called 'Start up of the nuclear power plant'. It was found that axisymmetric models, which consider non-axisymmetric components by correction factors, together with special attention to holes and other stress concentrations, allow a sufficient computation of stresses and deformations in the vessel, with the exception of the coolant nozzle region. In this latter case a fully three-dimensional analysis may be necessary.

  18. [Parent artery occlusion therapy for giant aneurysms of the vertebrobasilar system: hemodynamic analysis by hydraulic vascular model].

    Science.gov (United States)

    Nagayasu, S

    1992-03-01

    Although therapeutic occlusion of the basilar artery has been an accepted treatment for inaccessible giant aneurysms, several such problems have been reported as incomplete thrombosis, growth or rupture of aneurysms, cerebral embolism originating from an aneurysmal cavity. Hemodynamic changes after occlusion therapy are suspected to be responsible for these events. It is usually difficult to solve these problems or to predict them before operation because multiple factors are related in a complex fashion in a living body. One of the effective means is to simulate these hemodynamic conditions by a hydraulic vascular model. A glass-made sphere of 2.5 cm in diameter was connected to a hydraulic vascular model of the brain and was regarded as a giant aneurysm so as to evaluate hemodynamic changes after therapeutic occlusion of the parent artery. 40% glycerol solution at 25 degrees C, having similar viscosity and specific gravity to those of human whole blood at 37 degrees C, was used as a perfusate in this study. A device to measure a half-life of the dye injected in an aneurysm was made from a stable luminous source and a Cds photocell. Good correlation was obtained between the output from the device and dye concentration in an aneurysm. Intensity change of the transmitted light was measured when the dye was injected into the aneurysm during perfusion. Half-life was calculated from thus obtained clearance curve and was regarded as an index of intra-aneurysmal stagnation. The flow volumes have been estimated in our previous study: 60 ml/min to the territory of one posterior cerebral artery (PCA) and 80 ml/min to the cerebellum and the brain stem. A. Basilar artery occlusion therapy for a basilar bifurcation aneurysm. For the simulation before occlusion therapy, the flow volume of the basilar artery (BA) was fixed to be 120 ml/min. When the BA is occluded distal to the exit of the superior cerebellar artery, a flow tangential to the aneurysmal neck occurs from the side

  19. Interactive 3D Analysis of Blood Vessel Trees and Collateral Vessel Volumes in Magnetic Resonance Angiograms in the Mouse Ischemic Hindlimb Model.

    Science.gov (United States)

    Marks, Peter C; Preda, Marilena; Henderson, Terry; Liaw, Lucy; Lindner, Volkhard; Friesel, Robert E; Pinz, Ilka M

    2013-10-31

    The quantitative analysis of blood vessel volumes from magnetic resonance angiograms (MRA) or μCT images is difficult and time-consuming. This fact, when combined with a study that involves multiple scans of multiple subjects, can represent a significant portion of research time. In order to enhance analysis options and to provide an automated and fast analysis method, we developed a software plugin for the ImageJ and Fiji image processing frameworks that enables the quick and reproducible volume quantification of blood vessel segments. The novel plugin named Volume Calculator (VolCal), accepts any binary (thresholded) image and produces a three-dimensional schematic representation of the vasculature that can be directly manipulated by the investigator. Using MRAs of the mouse hindlimb ischemia model, we demonstrate quick and reproducible blood vessel volume calculations with 95 - 98% accuracy. In clinical settings this software may enhance image interpretation and the speed of data analysis and thus enhance intervention decisions for example in peripheral vascular disease or aneurysms. In summary, we provide a novel, fast and interactive quantification of blood vessel volumes for single blood vessels or sets of vessel segments with particular focus on collateral formation after an ischemic insult.

  20. Aortoiliac occlusive disease masquerading as cerebrovascular accident

    Directory of Open Access Journals (Sweden)

    Nandeesh B

    2007-01-01

    Full Text Available Acute aortoiliac occlusion is an unusual but potentially catastrophic condition causing acute limb ischemia and associated with early and high rates of mortality and morbidity. It is caused by either embolic occlusion of the infra renal aorta at the bifurcation or beyond or thrombosis of the abdominal aorta and its large terminal branches. Neurological symptoms are rare manifestation of acute aortoiliac occlusion and when neurological symptoms predominate, patients are mistakenly considered to have cerebrovascular event. We present a 60-year-old man with atherosclerotic thrombotic occlusion of the left common iliac artery causing acute painful monoplegia. We mistook the acute monoplegia due to acute limb ischemia for cerebrovascular accident. Pathologic examination revealed a firm thrombus occluding the origin of left common iliac artery and extending along the length of the vessel. Acute aortic iliac occlusion can masquerade as a cerebrovascular stroke and a thorough clinical evaluation and imaging studies allow early diagnosis and instituting life-saving treatment timely.

  1. The Sensitivity of State Differential Game Vessel Traffic Model

    Directory of Open Access Journals (Sweden)

    Lisowski Józef

    2016-04-01

    Full Text Available The paper presents the application of the theory of deterministic sensitivity control systems for sensitivity analysis implemented to game control systems of moving objects, such as ships, airplanes and cars. The sensitivity of parametric model of game ship control process in collision situations have been presented. First-order and k-th order sensitivity functions of parametric model of process control are described. The structure of the game ship control system in collision situations and the mathematical model of game control process in the form of state equations, are given. Characteristics of sensitivity functions of the game ship control process model on the basis of computer simulation in Matlab/Simulink software have been presented. In the end, have been given proposals regarding the use of sensitivity analysis to practical synthesis of computer-aided system navigator in potential collision situations.

  2. Combining operational models and data into a dynamic vessel risk assessment tool for coastal regions

    Science.gov (United States)

    Fernandes, R.; Braunschweig, F.; Lourenço, F.; Neves, R.

    2016-02-01

    The technological evolution in terms of computational capacity, data acquisition systems, numerical modelling and operational oceanography is supplying opportunities for designing and building holistic approaches and complex tools for newer and more efficient management (planning, prevention and response) of coastal water pollution risk events. A combined methodology to dynamically estimate time and space variable individual vessel accident risk levels and shoreline contamination risk from ships has been developed, integrating numerical metocean forecasts and oil spill simulations with vessel tracking automatic identification systems (AIS). The risk rating combines the likelihood of an oil spill occurring from a vessel navigating in a study area - the Portuguese continental shelf - with the assessed consequences to the shoreline. The spill likelihood is based on dynamic marine weather conditions and statistical information from previous accidents. The shoreline consequences reflect the virtual spilled oil amount reaching shoreline and its environmental and socio-economic vulnerabilities. The oil reaching shoreline is quantified with an oil spill fate and behaviour model running multiple virtual spills from vessels along time, or as an alternative, a correction factor based on vessel distance from coast. Shoreline risks can be computed in real time or from previously obtained data. Results show the ability of the proposed methodology to estimate the risk properly sensitive to dynamic metocean conditions and to oil transport behaviour. The integration of meteo-oceanic + oil spill models with coastal vulnerability and AIS data in the quantification of risk enhances the maritime situational awareness and the decision support model, providing a more realistic approach in the assessment of shoreline impacts. The risk assessment from historical data can help finding typical risk patterns ("hot spots") or developing sensitivity analysis to specific conditions, whereas real

  3. Analysis of Long-term Ex-vessel Debris Coolability with a Simple Model

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Byoung Cheol; Moriyama, Kiyofumi; Park, Hyun Sun [POSTECH, Pohang (Korea, Republic of)

    2016-05-15

    In the late phase of the severe accident in light water reactors (LWRs), assuring the coolability of ex-vessel core debris is important because it is the last barrier to prevent the accident progression before the radioactive release to the environment. If the debris cooling is unsuccessful, the heated and possibly re-melted core debris may induces molten core-concrete interaction (MCCI) that produces steam and non-condensable gases and causes the over-pressurization of containment vessel. Analysis for the long-term cooling of an ex-vessel debris bed was performed using a simple model developed by Hwang et al., and the model was originally developed to explain the feature of the debris bed in FARO experiments. It is assumed that the debris bed consists of a fluidized particles on top and a porous lump of sintered particles below. The bed formation process is also considered to determine the geometry and initial condition of the debris bed. Therefore, the simple model includes a wide range of cooling processes with a simplified zero or one-dimensional analysis. Sensitivity tests for the ex-vessel debris bed cooling behavior on selected input variables were performed using a modified version of a simple model developed by Hwang et al.. The model covers the series of phenomena from the breakup of the melt jet till the long-term cooling phase, and the results showed that the accumulation area of debris bed has significant impacts on the overall cooling performance.

  4. Modeling of a Piezoelectric MEMS Micropump Dedicated to Insulin Delivery and Experimental Validation Using Integrated Pressure Sensors: Application to Partial Occlusion Management

    Directory of Open Access Journals (Sweden)

    S. Fournier

    2017-01-01

    Full Text Available A numerical model based on equivalent electrical networks has been built to simulate the dynamic behavior of a positive-displacement MEMS micropump dedicated to insulin delivery. This device comprises a reservoir in direct communication with the inlet check valve, a pumping membrane actuated by a piezo actuator, two integrated piezoresistive pressure sensors, an anti-free-flow check valve at the outlet, and finally a fluidic pathway up to the patient cannula. The pressure profiles delivered by the sensors are continuously analyzed during the therapy in order to detect failures like occlusion. The numerical modeling is a reliable way to better understand the behavior of the micropump in case of failure. The experimental pressure profiles measured during the actuation phase have been used to validate the numerical modeling. The effect of partial occlusion on the pressure profiles has been also simulated. Based on this analysis, a new management of partial occlusion for MEMS micropump is finally proposed.

  5. Multiscale FEM modeling of vascular tone: from membrane currents to vessel mechanics.

    Science.gov (United States)

    Kapela, Adam; Tsoukias, Nikolaos Michael

    2011-12-01

    Regulation of vascular tone is a complex process that remains poorly understood. Here, we present our recent efforts for the development of physiologically realistic models of arterial segments for the analysis of vasoreactivity in health and disease. Multiscale modeling integrates intracellular and cell membrane components into whole-cell models of calcium and membrane potential dynamics. Single-cell models of vascular cells are combined into a multicellular model of the vascular wall, and vessel wall biomechanics are integrated with calcium dynamics in the smooth muscle layer. At each scale, continuum models using finite element method can account for spatial heterogeneity in calcium signaling and for nonuniform deformations of a vessel segment. The outlined approach can be used to investigate cellular mechanisms underlying altered vasoreactivity in hypertension.

  6. MATHEMATICAL MODELING OF WELDING BLOOD VESSELS BY ELECTROSURGERY FORCEPS

    Directory of Open Access Journals (Sweden)

    Yarova S.O.

    2016-02-01

    Full Text Available Electrosurgical instruments for the coagulation of biological tissue is used in almost all surgical operations. SolidWorks modeling allows to obtain the distribution of the mechanical stresses, displacements and strains. The design of all types of forceps are made so that the electrodes were positioned at an angle. This improves the grip of the tissue, but leads to uneven compression. Bending the jaws of the forceps improves the uniformity of the stress distribution

  7. Vessel grounding in entrance channels: case studies and physical model tests

    CSIR Research Space (South Africa)

    Tulsi, K

    2014-05-01

    Full Text Available off the channel slope and back into the entrance channel. The tests were conducted at the Coastal & Hydraulics Laboratory, of the CSIR in Stellenbosch, South Africa. Simulated vessel grounding was modelled in a hydraulic basin at a scale of 1:100. Over...

  8. Modeling of the mooring to the partner vessel using innovative vessel’s steering methods

    Directory of Open Access Journals (Sweden)

    Kholichev S.N.

    2015-03-01

    Full Text Available The innovative mooring method of one vessel to another in the open sea conditions has been proposed. The model experiment of the first stage of mooring has been conducted. The possibility of application of the proposed method in practice has been proved

  9. Computational Fluid Dynamics Analysis of Pulsatile Blood Flow Behavior in Modelled Stenosed Vessels with Different Severities

    Directory of Open Access Journals (Sweden)

    Mohsen Mehrabi

    2012-01-01

    Full Text Available This study focuses on the behavior of blood flow in the stenosed vessels. Blood is modelled as an incompressible non-Newtonian fluid which is based on the power law viscosity model. A numerical technique based on the finite difference method is developed to simulate the blood flow taking into account the transient periodic behaviour of the blood flow in cardiac cycles. Also, pulsatile blood flow in the stenosed vessel is based on the Womersley model, and fluid flow in the lumen region is governed by the continuity equation and the Navier-Stokes equations. In this study, the stenosis shape is cosine by using Tu and Devil model. Comparing the results obtained from three stenosed vessels with 30%, 50%, and 75% area severity, we find that higher percent-area severity of stenosis leads to higher extrapressure jumps and higher blood speeds around the stenosis site. Also, we observe that the size of the stenosis in stenosed vessels does influence the blood flow. A little change on the cross-sectional value makes vast change on the blood flow rate. This simulation helps the people working in the field of physiological fluid dynamics as well as the medical practitioners.

  10. Ex vivo blood vessel bioreactor for analysis of the biodegradation of magnesium stent models with and without vessel wall integration.

    Science.gov (United States)

    Wang, Juan; Liu, Lumei; Wu, Yifan; Maitz, Manfred F; Wang, Zhihong; Koo, Youngmi; Zhao, Ansha; Sankar, Jagannathan; Kong, Deling; Huang, Nan; Yun, Yeoheung

    2017-03-01

    Current in vitro models fail in predicting the degradation rate and mode of magnesium (Mg) stents in vivo. To overcome this, the microenvironment of the stent is simulated here in an ex vivo bioreactor with porcine aorta and circulating medium, and compared with standard static in vitro immersion and with in vivo rat aorta models. In ex vivo and in vivo conditions, pure Mg wires were exposed to the aortic lumen and inserted into the aortic wall to mimic early- and long-term implantation, respectively. Results showed that: 1) Degradation rates of Mg were similar for all the fluid diffusion conditions (in vitro static, aortic wall ex vivo and in vivo); however, Mg degradation under flow condition (i.e. in the lumen) in vivo was slower than ex vivo; 2) The corrosion mode in the samples can be mainly described as localized (in vitro), mixed localized and uniform (ex vivo), and uniform (in vivo); 3) Abundant degradation products (MgO/Mg(OH)2 and Ca/P) with gas bubbles accumulated around the localized degradation regions ex vivo, but a uniform and thin degradation product layer was found in vivo. It is concluded that the ex vivo vascular bioreactor provides an improved test setting for magnesium degradation between static immersion and animal experiments and highlights its promising role in bridging degradation behavior and biological response for vascular stent research. Magnesium and its alloys are candidates for a new generation of biodegradable stent materials. However, the in vitro degradation of magnesium stents does not match the clinical degradation rates, corrupting the validity of conventional degradation tests. Here we report an ex vivo vascular bioreactor, which allows simulation of the microenvironment with and without blood vessel integration to study the biodegradation of magnesium implants in comparison with standard in vitro test conditions and with in vivo implantations. The bioreactor did simulate the corrosion of an intramural implant very well, but

  11. State-space representation of radiation forces in time-domain vessel models

    Directory of Open Access Journals (Sweden)

    Erlend Kristiansen

    2006-01-01

    Full Text Available The paper presents a method for generating a new and efficient time-domain formulation of the equations of motion for a vessel with frequency-dependent hydrodynamic coefficients. Previous work on this topic has relied on the use of convolution terms, whereas in this work state-space models are used. This leads to a model formulation that is well suited for controller design and simulation.

  12. Protective effects of allicin against ischemic stroke in a rat model of middle cerebral artery occlusion.

    Science.gov (United States)

    Zhang, Benping; Li, Feng; Zhao, Weijiang; Li, Jiebing; Li, Qingsong; Wang, Weizhi

    2015-09-01

    Allicin, a molecule predominantly responsible for the pungent odor and the antibiotic function of garlic, exhibits various pharmacological activities and has been suggested to be beneficial in the treatment of various disorders. The present study aimed to elucidate the effect of allicin in cerebral ischemia/reperfusion (I/R) injury in rats. Rats were subjected to 1.5 h of transient middle cerebral artery occlusion (MCAO), followed by 24 h of reperfusion. Rats were randomly assigned to the sham surgery group, the MCAO group and the MCAO + allicin group. Neurological score, cerebral infarct size, brain water content, neuronal apoptosis, serum tumor necrosis factor (TNF)‑α and myeloperoxidase (MPO) activity were measured. The results suggested that allicin reduced cerebral infarction area, brain water content, neuronal apoptosis, TNF‑α levels and MPO activity in the serum. The results of the present study indicated that allicin protects the brain from cerebral I/R injury, which may be ascribed to its anti‑apoptotic and anti‑inflammatory effects.

  13. 3D printing model of the intrahepatic vessels for navigation during anatomical resection of hepatocellular carcinoma.

    Science.gov (United States)

    Kuroda, Shintaro; Kobayashi, Tsuyoshi; Ohdan, Hideki

    2017-10-26

    The 3D printing model of the intrahepatic vessels and regional anatomy are often used for navigation surgery. Here, we report the use of the model for anatomical resection of hepatocellular carcinoma. Case 1: A tumor, 31mm in diameter, was located in segment 7 of the liver. Using the 3D model, we identified the regional Glissonian pedicle and performed resection of segment 7. Case 2: The tumor was located in segment 4/8 and involved the middle hepatic vein. Radical resection of segment 4 and of the ventral area of the right anterior section was performed using the 3D model. The positional relationship between the intrahepatic vessels and liver tumors is the most important factor for anatomical resection for hepatocellular carcinoma. Therefore our simplified 3D model of intrahepatic vessels without liver parenchyma is sufficient for effective guidance during surgery and has the advantage of being feasible to use for all HCC surgeries. Use of 3D printed models might have many merits and contribute to the great improvement of the surgical quality. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. Lower Length Scale Model Development for Embrittlement of Reactor Presure Vessel Steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yongfeng [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schwen, Daniel [Idaho National Lab. (INL), Idaho Falls, ID (United States); Chakraborty, Pritam [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bai, Xianming [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-01

    This report summarizes the lower-length-scale effort during FY 2016 in developing mesoscale capabilities for microstructure evolution, plasticity and fracture in reactor pressure vessel steels. During operation, reactor pressure vessels are subject to hardening and embrittlement caused by irradiation induced defect accumulation and irradiation enhanced solute precipitation. Both defect production and solute precipitation start from the atomic scale, and manifest their eventual effects as degradation in engineering scale properties. To predict the property degradation, multiscale modeling and simulation are needed to deal with the microstructure evolution, and to link the microstructure feature to material properties. In this report, the development of mesoscale capabilities for defect accumulation and solute precipitation are summarized. A crystal plasticity model to capture defect-dislocation interaction and a damage model for cleavage micro-crack propagation is also provided.

  15. Effort dynamics in a fisheries bioeconomic model: A vessel level approach through Game Theory

    Directory of Open Access Journals (Sweden)

    Gorka Merino

    2007-09-01

    Full Text Available Red shrimp, Aristeus antennatus (Risso, 1816 is one of the most important resources for the bottom-trawl fleets in the northwestern Mediterranean, in terms of both landings and economic value. A simple bioeconomic model introducing Game Theory for the prediction of effort dynamics at vessel level is proposed. The game is performed by the twelve vessels exploiting red shrimp in Blanes. Within the game, two solutions are performed: non-cooperation and cooperation. The first is proposed as a realistic method for the prediction of individual effort strategies and the second is used to illustrate the potential profitability of the analysed fishery. The effort strategy for each vessel is the number of fishing days per year and their objective is profit maximisation, individual profits for the non-cooperative solution and total profits for the cooperative one. In the present analysis, strategic conflicts arise from the differences between vessels in technical efficiency (catchability coefficient and economic efficiency (defined here. The ten-year and 1000-iteration stochastic simulations performed for the two effort solutions show that the best strategy from both an economic and a conservationist perspective is homogeneous effort cooperation. However, the results under non-cooperation are more similar to the observed data on effort strategies and landings.

  16. Testing of plain and fibrous concrete single cavity prestressed concrete reactor vessel models

    Energy Technology Data Exchange (ETDEWEB)

    Oland, C.B.

    1985-01-01

    Two single-cavity prestressed concrete reactor vessel (PCRV) models were fabricated and tested to failure to demonstrate the structural response and ultimate pressure capacity of models cast from high-strength concretes. Concretes with design compressive strengths in excess of 70 MPa (10,000 psi) were developed for this investigation. One model was cast from plain concrete and failed in shear at the head region. The second model was cast from fiber reinforced concrete and failed by rupturing the circumferential prestressing at the sidewall of the structure. The tests also demonstrated the capabilities of the liner system to maintain a leak-tight pressure boundary. 3 refs., 4 figs.

  17. A Multiscale Modeling Approach to Analyze Filament-Wound Composite Pressure Vessels

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ba Nghiep; Simmons, Kevin L.

    2013-07-22

    A multiscale modeling approach to analyze filament-wound composite pressure vessels is developed in this article. The approach, which extends the Nguyen et al. model [J. Comp. Mater. 43 (2009) 217] developed for discontinuous fiber composites to continuous fiber ones, spans three modeling scales. The microscale considers the unidirectional elastic fibers embedded in an elastic-plastic matrix obeying the Ramberg-Osgood relation and J2 deformation theory of plasticity. The mesoscale behavior representing the composite lamina is obtained through an incremental Mori-Tanaka type model and the Eshelby equivalent inclusion method [Proc. Roy. Soc. Lond. A241 (1957) 376]. The implementation of the micro-meso constitutive relations in the ABAQUS® finite element package (via user subroutines) allows the analysis of a filament-wound composite pressure vessel (macroscale) to be performed. Failure of the composite lamina is predicted by a criterion that accounts for the strengths of the fibers and of the matrix as well as of their interface. The developed approach is demonstrated in the analysis of a filament-wound pressure vessel to study the effect of the lamina thickness on the burst pressure. The predictions are favorably compared to the numerical and experimental results by Lifshitz and Dayan [Comp. Struct. 32 (1995) 313].

  18. A Constraint Programming model for fast optimal stowage of container vessel bays

    DEFF Research Database (Denmark)

    Delgado, Alberto; Jensen, Rune Møller; Janstrup, Kira

    2012-01-01

    planning phase that distributes the containers to bay sections and a slot planning phase that assigns containers of each bay section to slots. In this paper, we focus on the slot planning phase of this approach and present a Constraint Programming and Integer Programming model for stowing a set......Container vessel stowage planning is a hard combinatorial optimization problem with both high economic and environmental impact. We have developed an approach that often is able to generate near-optimal plans for large container vessels within a few minutes. It decomposes the problem into a master...... of containers in a single bay section. This so-called slot planning problem is NP-hard and often involves stowing several hundred containers. Using state-of-the-art constraint solvers and modeling techniques, however, we were able to solve 90% of 236 real instances from our industrial collaborator to optimality...

  19. Development of FB-MultiPier dynamic vessel-collision analysis models, phase 2 : [summary].

    Science.gov (United States)

    2014-07-01

    When collisions between large vessels and bridge : supports occur, they can result in significant : damage to bridge and vessel. These collisions : are extremely hazardous, often taking lives on : the vessel and the bridge. Direct costs of repair : a...

  20. Development of FB-MultiPier dynamic vessel-collision analysis models, phase 2.

    Science.gov (United States)

    2014-07-01

    Massive waterway vessels such as barges regularly transit navigable waterways in the U.S. During passages that fall within : the vicinity of bridge structures, vessels may (under extreme circumstances) deviate from the intended vessel transit path. A...

  1. Mathematical Models and Numerical Simulations for the Blood Flow in Large Vessels

    OpenAIRE

    Titus PETRILA; Balazs ALBERT

    2012-01-01

    We are proposing a non-Newtonian, Cross type rheological model for the blood flow, under the conditions of an unsteady flow regime connected with the rhythmic pumping of the blood by the heart. We admit the incompressibility and homogeneity of the blood while its flow is laminar and the exterior body forces are neglected. We take also into account the viscoelastic behavior of the vessel walls. The mathematical equations and the appropriate boundary conditions are considered in cylindrical (ax...

  2. Combined surface and volumetric occlusion shading

    KAUST Repository

    Schott, Matthias O.

    2012-02-01

    In this paper, a method for interactive direct volume rendering is proposed that computes ambient occlusion effects for visualizations that combine both volumetric and geometric primitives, specifically tube shaped geometric objects representing streamlines, magnetic field lines or DTI fiber tracts. The proposed algorithm extends the recently proposed Directional Occlusion Shading model to allow the rendering of those geometric shapes in combination with a context providing 3D volume, considering mutual occlusion between structures represented by a volume or geometry. © 2012 IEEE.

  3. Vessel Operating Units (Vessels)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains data for vessels that are greater than five net tons and have a current US Coast Guard documentation number. Beginning in1979, the NMFS...

  4. Bilateral retinal vein occlusion and rubeosis irides: lessons to learn.

    Directory of Open Access Journals (Sweden)

    Umi Kalthum Md Noh

    2013-09-01

    Full Text Available Uncontrolled hypertension is well- known to give rise to systemic complications involving multiple central organs. Artherosclerosis leads to damage of the retinal vessels wall, contributing to venous stasis, thrombosis and finally, occlusion. Retinal vein occlusions compromise vision through development of ischaemic maculopathy, macular oedema, and rubeotic glaucoma. Laser photocoagulation remains the definitive treatment for ischaemic vein occlusion with secondary neovascularization. Timely treatment with anti- vascular endothelial growth factor prevents development of rubeotic glaucoma. We hereby report an unusual case of bilateral retinal vein occlusion complicated by rubeosis irides, which was successfully managed to improve vision and prevent rubeotic glaucoma.

  5. Pulmonary transcriptome analysis in the surgically induced rabbit model of diaphragmatic hernia treated with fetal tracheal occlusion

    Directory of Open Access Journals (Sweden)

    Alexander C. Engels

    2016-02-01

    Full Text Available Congenital diaphragmatic hernia (CDH is a malformation leading to pulmonary hypoplasia, which can be treated in utero by fetal tracheal occlusion (TO. However, the changes of gene expression induced by TO remain largely unknown but could be used to further improve the clinically used prenatal treatment of this devastating malformation. Therefore, we aimed to investigate the pulmonary transcriptome changes caused by surgical induction of diaphragmatic hernia (DH and additional TO in the fetal rabbit model. Induction of DH was associated with 378 upregulated genes compared to controls when allowing a false-discovery rate (FDR of 0.1 and a fold change (FC of 2. Those genes were again downregulated by consecutive TO. But DH+TO was associated with an upregulation of 157 genes compared to DH and controls. When being compared to control lungs, 106 genes were downregulated in the DH group and were not changed by TO. Therefore, the overall pattern of gene expression in DH+TO is more similar to the control group than to the DH group. In this study, we further provide a database of gene expression changes induced by surgical creation of DH and consecutive TO in the rabbit model. Future treatment strategies could be developed using this dataset. We also discuss the most relevant genes that are involved in CDH.

  6. Pulmonary transcriptome analysis in the surgically induced rabbit model of diaphragmatic hernia treated with fetal tracheal occlusion.

    Science.gov (United States)

    Engels, Alexander C; Brady, Paul D; Kammoun, Molka; Finalet Ferreiro, Julio; DeKoninck, Philip; Endo, Masayuki; Toelen, Jaan; Vermeesch, Joris R; Deprest, Jan

    2016-02-01

    Congenital diaphragmatic hernia (CDH) is a malformation leading to pulmonary hypoplasia, which can be treated in utero by fetal tracheal occlusion (TO). However, the changes of gene expression induced by TO remain largely unknown but could be used to further improve the clinically used prenatal treatment of this devastating malformation. Therefore, we aimed to investigate the pulmonary transcriptome changes caused by surgical induction of diaphragmatic hernia (DH) and additional TO in the fetal rabbit model. Induction of DH was associated with 378 upregulated genes compared to controls when allowing a false-discovery rate (FDR) of 0.1 and a fold change (FC) of 2. Those genes were again downregulated by consecutive TO. But DH+TO was associated with an upregulation of 157 genes compared to DH and controls. When being compared to control lungs, 106 genes were downregulated in the DH group and were not changed by TO. Therefore, the overall pattern of gene expression in DH+TO is more similar to the control group than to the DH group. In this study, we further provide a database of gene expression changes induced by surgical creation of DH and consecutive TO in the rabbit model. Future treatment strategies could be developed using this dataset. We also discuss the most relevant genes that are involved in CDH. © 2016. Published by The Company of Biologists Ltd.

  7. The neuroprotective action of dizocilpine (MK-801) in the rat middle cerebral artery occlusion model of focal ischaemia.

    Science.gov (United States)

    Gill, R; Brazell, C; Woodruff, G N; Kemp, J A

    1991-08-01

    1. An acute model of focal ischaemia, which involves permanent occlusion of the middle cerebral artery of the rat with 4 h survival, was used to find the minimum effective plasma concentration of dizocilpine (MK-801) and to determine its dose-effect relationship. 2. MK-801 was administered at the time of occlusion and was given as an i.v. bolus followed by an infusion for 4 h to maintain a steady state plasma concentration of the drug throughout the study. MK-801 was given at 3 dose levels; 0.04 mg kg-1 i.v. bolus + 0.6 micrograms kg-1 min-1 infusion; 0.12 mg kg-1 i.v. bolus + 1.8 micrograms kg-1 min-1 infusion; 0.4 mg kg-1 i.v. bolus + 6 micrograms kg-1 min-1 infusion, which gave mean plasma levels over the 4 h of 8.0 ng ml-1, 18.9 ng ml-1 and 113.2 ng ml-1 respectively. 3. MK-801 at 8.0 ng ml-1 gave 10% reduction in the volume of ischaemic brain damage in the cerebral cortex which just reached significance. The middle dose of MK-801 (18.9 ng ml-1) gave a highly significant reduction in the volume of ischaemic brain damage in the cerebral cortex and hemisphere, volumes of ischaemic tissue being reduced by 60% and 50% compared to saline-treated animals, respectively. The highest plasma concentration of MK-801 (113.2 ng ml-1) resulted in a 35% reduction in the volume of hemispheric damage and a 40% reduction in the volume of cortical damage, which were significant.4. The reduction in the amount of protection afforded by the highest dose of MK-801 may be due to the hypotensive effect of this dose. There was no protection against the volume of damage in the caudate nucleus for any of the doses of MK-801 tested.5. Therefore the minimum effective plasma concentration of MK-801 was 8.0 ngml1, although the greatest protection was seen with a plasma level of 18.9 ng ml- 1. This correlates well with the concentration of MK-801 required to block N-methyl-D-aspartate (NMDA) receptors and prevent NMDA receptor mediated neurotoxicity in vitro.

  8. The effect of collateral flow and myocardial viability on the distribution of technetium-99m sestamibi in a closed-chest model of coronary occlusion and reperfusion

    Energy Technology Data Exchange (ETDEWEB)

    Chareonthaitawee, P. [MRC Cyclotron Unit, Hammersmith Hospital, London (United Kingdom); Div. of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Mayo Foundation, Rochester, MN (United States); O' Connor, M.K. [Dept. of Nuclear Medicine, Mayo Clinic and Mayo Foundation, Rochester, MN (United States); Gibbons, R.J.; Christian, T.F. [Div. of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Mayo Foundation, Rochester, MN (United States); Ritman, E.L. [Dept. of Physiology, Mayo Clinic and Mayo Foundation, Rochester, MN (United States)

    2000-05-01

    The objective of this study was to determine the effect of myocardial viability and the degree of collateral blood flow on the uptake and retention of {sup 99m}Tc-sestamibi by examining three animal models of coronary occlusion and reperfusion, each reflecting a different state of viability and collateral blood flow. Three closed-chest animal models were studied: canine (high collateral flow, preserved viability), porcine (low collateral flow, absent viability) and porcine with slowly occlusive coronary stents producing infarction and enhanced collateral blood flow (high collateral flow, absent viability). There were seven dogs, seven pigs and six pigs, respectively, in each animal model. Animals from all three models were subjected to a 40-min total left anterior descending artery (LAD) occlusion followed by 2 h of reperfusion. {sup 99m}Tc-sestamibi and radiolabelled microspheres were injected during LAD occlusion 10 min prior to reperfusion. Animals were sacrificed after 2 h of reperfusion flow. Ex situ heart slice imaging to determine risk area was followed by viability staining to determine infarct size. Slices were subsequently sectioned into equally sized radial segments and placed in a gamma well counter. Risk area as determined by ex situ {sup 99m}Tc-sestamibi imaging was not significantly different by model. Pathological infarct size differed significantly by model [canine = 1%{+-}1% of the left ventricle (LV); porcine = 13%{+-}8% LV; porcine with stent = 14%{+-}7% LV; P=0.002]. Collateral blood flow by microspheres during occlusion tended to differ among models (overall P=0.08), with the canine and porcine with stent models having relatively high flow rates compared with the acute porcine model. {sup 99m}Tc-sestamibi activity correlated with microsphere blood flow in all three models, with r values for individual animals (n=20) ranging from 0.86 to 0.96 (all P<0.0001). There was a significant difference in the regression line intercepts (P<0.0001) and

  9. Integrated Analysis of Expression Profile Based on Differentially Expressed Genes in Middle Cerebral Artery Occlusion Animal Models

    Directory of Open Access Journals (Sweden)

    Huaqiang Zhou

    2016-05-01

    Full Text Available Stroke is one of the most common causes of death, only second to heart disease. Molecular investigations about stroke are in acute shortage nowadays. This study is intended to explore a gene expression profile after brain ischemia reperfusion. Meta-analysis, differential expression analysis, and integrated analysis were employed on an eight microarray series. We explored the functions and pathways of target genes in gene ontology (GO enrichment analysis and constructed a protein-protein interaction network. Meta-analysis identified 360 differentially expressed genes (DEGs for Mus musculus and 255 for Rattus norvegicus. Differential expression analysis identified 44 DEGs for Mus musculus and 21 for Rattus norvegicus. Timp1 and Lcn2 were overexpressed in both species. The cytokine-cytokine receptor interaction and chemokine signaling pathway were highly enriched for the Kyoto Encyclopedia of Genes and Genomes (KEGG pathway. We have exhibited a global view of the potential molecular differences between middle cerebral artery occlusion (MCAO animal model and sham for Mus musculus or Rattus norvegicus, including the biological process and enriched pathways in DEGs. This research helps contribute to a clearer understanding of the inflammation process and accurate identification of ischemic infarction stages, which might be transformed into a therapeutic approach.

  10. Two-photon imaging of cortical surface microvessels reveals a robust redistribution in blood flow after vascular occlusion.

    Directory of Open Access Journals (Sweden)

    Chris B Schaffer

    2006-02-01

    Full Text Available A highly interconnected network of arterioles overlies mammalian cortex to route blood to the cortical mantle. Here we test if this angioarchitecture can ensure that the supply of blood is redistributed after vascular occlusion. We use rodent parietal cortex as a model system and image the flow of red blood cells in individual microvessels. Changes in flow are quantified in response to photothrombotic occlusions to individual pial arterioles as well as to physical occlusions of the middle cerebral artery (MCA, the primary source of blood to this network. We observe that perfusion is rapidly reestablished at the first branch downstream from a photothrombotic occlusion through a reversal in flow in one vessel. More distal downstream arterioles also show reversals in flow. Further, occlusion of the MCA leads to reversals in flow through approximately half of the downstream but distant arterioles. Thus the cortical arteriolar network supports collateral flow that may mitigate the effects of vessel obstruction, as may occur secondary to neurovascular pathology.

  11. A Novel Through Capacity Model for One-way Channel Based on Characteristics of the Vessel Traffic Flow

    Directory of Open Access Journals (Sweden)

    Yuanyuan Nie

    2017-09-01

    Full Text Available Vessel traffic flow is a key parameter for channel-through capacity and is of great significance to vessel traffic management, channel and port design and navigational risk evaluation. Based on the study of parameters of characteristics of vessel traffic flow related to channel-through capacity, this paper puts forward a brand-new mathematical model for one-way channel-through capacity in which parameters of channel length, vessel arrival rate and velocity difference in different vessels are involved and a theoretical calculating mechanism for the channel-through capacity is provided. In order to verify availability and reliability of the model, extensive simulation studies have been carried out and based on the historical AIS data, an analytical case study on the Xiazhimen Channel validating the proposed model is presented. Both simulation studies and the case study show that the proposed model is valid and all relative parameters can be readjusted and optimized to further improve the channel-through capacity. Thus, all studies demonstrate that the model is valuable for channel design and vessel management.

  12. Investigation of retinal morphology alterations using spectral domain optical coherence tomography in a mouse model of retinal branch and central retinal vein occlusion.

    Directory of Open Access Journals (Sweden)

    Andreas Ebneter

    Full Text Available Retinal vein occlusion is a leading cause of visual impairment. Experimental models of this condition based on laser photocoagulation of retinal veins have been described and extensively exploited in mammals and larger rodents such as the rat. However, few reports exist on the use of this paradigm in the mouse. The objective of this study was to investigate a model of branch and central retinal vein occlusion in the mouse and characterize in vivo longitudinal retinal morphology alterations using spectral domain optical coherence tomography. Retinal veins were experimentally occluded using laser photocoagulation after intravenous application of Rose Bengal, a photo-activator dye enhancing thrombus formation. Depending on the number of veins occluded, variable amounts of capillary dropout were seen on fluorescein angiography. Vascular endothelial growth factor levels were markedly elevated early and peaked at day one. Retinal thickness measurements with spectral domain optical coherence tomography showed significant swelling (p<0.001 compared to baseline, followed by gradual thinning plateauing two weeks after the experimental intervention (p<0.001. Histological findings at day seven correlated with spectral domain optical coherence tomography imaging. The inner layers were predominantly affected by degeneration with the outer nuclear layer and the photoreceptor outer segments largely preserved. The application of this retinal vein occlusion model in the mouse carries several advantages over its use in other larger species, such as access to a vast range of genetically modified animals. Retinal changes after experimental retinal vein occlusion in this mouse model can be non-invasively quantified by spectral domain optical coherence tomography, and may be used to monitor effects of potential therapeutic interventions.

  13. Bilateral carotid artery injury response in side impact using a vessel model integrated with a human body model.

    Science.gov (United States)

    Danelson, Kerry A; Gayzik, F Scott; Yu, Mao M; Martin, R Shayn; Duma, Stefan M; Stitzel, Joel D

    2009-10-01

    In a far-side crash configuration, the occupant can experience severe excursion from the seat space. Given this challenge, there are research efforts focused on alternate restraints, such as four-point belts. A potential implication of this geometry would be interaction of the belt with the occupant's neck. This study examines the response of the carotid arteries using a Finite Element Model (FEM) in a far-side crash configuration with a reversed three-point restraint. A FEM of the carotid artery and neck fascia was developed and integrated with the Total Human Model for Safety (THUMS) version 1.44. This model was subjected to four test conditions simulating far-side crashes. Load conditions included a low velocity impact of approximately 4 m/s and a higher velocity impact of approximately 10 m/s. For each velocity, the model was restrained with a belt placed low on the neck and a belt placed higher on the neck. Strain data in each element of the carotid arteries was analyzed. The overall response of the vessel was examined to determine locations of high strain values. Low belt placement resulted in more head excursion, stretching the carotid on the non-struck side. High belt placement resulted in compression of the artery on the struck side due to direct loading of the vessel from the belt. Strain values in the carotid artery elements increased with increasing speed of impact. The lower and higher speed tests with a low belt configuration resulted in a maximum principal strains, at maximal belt engagement, of 0.223 and 0.459, respectively. Corresponding values for the high belt configuration were 0.222 and 0.563. In both belt configurations, the non-struck side vessel stretched more than the struck side vessel; however, the non-struck side vessel experienced higher compressive forces. Strain values measured during the simulations can be compared to a value of 0.31 to intimal failure in previous experimental tests. These results quantitatively illustrate the two

  14. Cerebro-afferent vessel and pupillary basal diameter variation induced by stomatognathic trigeminal proprioception: a case report

    Directory of Open Access Journals (Sweden)

    De Cicco Vincenzo

    2012-09-01

    Full Text Available Abstract Introduction A patient affected by asymmetric hemodynamics of cerebro-afferent vessels underwent duplex color scanner investigations in occlusal proprioceptive un- and rebalance conditions. Pupillometric video-oculographic examinations were performed in order to spot connected trigeminal proprioceptive motor patterns able to interfere on sympathetic autonomic activity. The aim of this case report is to verify if involuntary jaw closing during swallowing, executed in unbalance and rebalance myoelectric activity, would be able to modify cerebral hemodynamics. Case presentation A 56-year-old Caucasian Italian woman affected by asymmetric blood flow of cerebro-afferent vessels underwent an electromyographic investigation of her occlusal muscles in order to assess their occlusal functional balance. The extreme asymmetry of myoelectric activity in dental occlusion evidenced by electromyographic values suggested the rebalancing of the functions of occlusal muscles through concurrent transcutaneous stimulation of the trigeminal nerve supra- and submandibular motor branches. The above-mentioned method allowed the detection of a symmetric craniomandibular muscular relation that can be kept constant through the use of a cusp bite modeled on the inferior dental arch: called orthotic-syntropic bite for its peculiar use of electrostimulation. A few days later, the patient underwent a duplex color scanner investigation and pupillometric video-oculographic examinations in occlusal unbalance and rebalance conditions. Conclusions A comparative data analysis showed that an unbalanced dental occlusal function may represent an interferential pattern on cerebral hemodynamics velocity and pupillometric evaluations have proved useful both in the analysis of locus coeruleus functional modalities and as a diagnostic tool in the assessment of pathologies involving locus coeruleus and autonomic systems. The inclusion of myoelectric masseter examinations can be

  15. Cerebro-afferent vessel and pupillary basal diameter variation induced by stomatognathic trigeminal proprioception: a case report.

    Science.gov (United States)

    De Cicco, Vincenzo

    2012-09-03

    A patient affected by asymmetric hemodynamics of cerebro-afferent vessels underwent duplex color scanner investigations in occlusal proprioceptive un- and rebalance conditions. Pupillometric video-oculographic examinations were performed in order to spot connected trigeminal proprioceptive motor patterns able to interfere on sympathetic autonomic activity. The aim of this case report is to verify if involuntary jaw closing during swallowing, executed in unbalance and rebalance myoelectric activity, would be able to modify cerebral hemodynamics. A 56-year-old Caucasian Italian woman affected by asymmetric blood flow of cerebro-afferent vessels underwent an electromyographic investigation of her occlusal muscles in order to assess their occlusal functional balance. The extreme asymmetry of myoelectric activity in dental occlusion evidenced by electromyographic values suggested the rebalancing of the functions of occlusal muscles through concurrent transcutaneous stimulation of the trigeminal nerve supra- and submandibular motor branches. The above-mentioned method allowed the detection of a symmetric craniomandibular muscular relation that can be kept constant through the use of a cusp bite modeled on the inferior dental arch: called orthotic-syntropic bite for its peculiar use of electrostimulation. A few days later, the patient underwent a duplex color scanner investigation and pupillometric video-oculographic examinations in occlusal unbalance and rebalance conditions. A comparative data analysis showed that an unbalanced dental occlusal function may represent an interferential pattern on cerebral hemodynamics velocity and pupillometric evaluations have proved useful both in the analysis of locus coeruleus functional modalities and as a diagnostic tool in the assessment of pathologies involving locus coeruleus and autonomic systems. The inclusion of myoelectric masseter examinations can be useful in patients with asymmetric hemodynamics of cerebro

  16. Modeling Relevant to Safe Operations of U.S. Navy Vessels in Arctic Conditions: Physical Modeling of Ice Loads

    Science.gov (United States)

    2016-06-01

    www.erdc.usace.army.mil. To search for other technical reports published by ERDC, visit the ERDC online library at http://acwc.sdp.sirsi.net/ client /default...Science and Technology SNAME Society of Naval Architects and Marine Engineers SSC Ship Structure Committee USCG U.S. Coast Guard WMO World...ice-capable vessels, naval architects have traditionally used physical modeling to measure the vessels’ re- sistance, propulsion, and maneuvering

  17. Weakly swirling flow in a model of blood vessel with stenosis: Numerical and experimental study

    Directory of Open Access Journals (Sweden)

    Yakov A. Gataulin

    2015-12-01

    Full Text Available Investigation of weakly swirling flow in a model of a blood vessel with asymmetrical stenosis has been performed using both experimental flow measurement techniques (ultrasound Doppler and computational fluid dynamics methods. A special attention is paid to getting data for the length of the reverse-flow zone occurring past the stenosis. It has been established that the laminar steady-state flow model is acceptable for numerical analysis of flow past the given-geometry stenosis at Reynolds number values less than 300. At higher values of this parameter, application of the semi-empirical k-ω SST turbulence model is preferable. It has been shown that flow swirl can lead to an increase of the reverse-flow zone.

  18. Preventive effect of yuzu and hesperidin on left ventricular remodeling and dysfunction in rat permanent left anterior descending coronary artery occlusion model.

    Science.gov (United States)

    Yu, Hye Yon; Ahn, Ji Hun; Park, Se Won; Jung, Yi-Sook

    2015-01-01

    Left ventricular (LV) remodeling, which includes ventricular dilatation and increased interstitial fibrosis after myocardial infarction (MI), is the critical process underlying the progression to heart failure. Therefore, a novel approach for preventing LV remodeling after MI is highly desirable. Yuzu is a citrus plant originating in East Asia, and has a number of cardioprotective properties such as hesperidin. However, no study has proved whether yuzu can prevent LV remodeling. The aim of this study was to determine the effects of yuzu on heart failure (HF) and its potential impact on the LV remodeling process after MI. Our in vivo study using the permanent left anterior descending coronary artery (LAD) occlusion model demonstrate that one week pre-treatment with yuzu or its major metabolite hesperidin before LAD occlusion significantly attenuated cardiac dysfunction, myocyte apoptosis and inflammation. Not only yuzu but also hesperidin inhibited caspase-3 activity, myeloperoxidase expression, α-smooth muscle actin expression, and matrix metalloproteinase-2 activity in a permanent LAD occlusion rat model. To our knowledge, our findings provide the first evidence that yuzu and hesperidin prevent MI-induced ventricular dysfunction and structural remodeling of myocardium.

  19. Preventive Effect of Yuzu and Hesperidin on Left Ventricular Remodeling and Dysfunction in Rat Permanent Left Anterior Descending Coronary Artery Occlusion Model

    Science.gov (United States)

    Yu, Hye Yon; Ahn, Ji Hun; Park, Se Won; Jung, Yi-Sook

    2015-01-01

    Left ventricular (LV) remodeling, which includes ventricular dilatation and increased interstitial fibrosis after myocardial infarction (MI), is the critical process underlying the progression to heart failure. Therefore, a novel approach for preventing LV remodeling after MI is highly desirable. Yuzu is a citrus plant originating in East Asia, and has a number of cardioprotective properties such as hesperidin. However, no study has proved whether yuzu can prevent LV remodeling. The aim of this study was to determine the effects of yuzu on heart failure (HF) and its potential impact on the LV remodeling process after MI. Our in vivo study using the permanent left anterior descending coronary artery (LAD) occlusion model demonstrate that one week pre-treatment with yuzu or its major metabolite hesperidin before LAD occlusion significantly attenuated cardiac dysfunction, myocyte apoptosis and inflammation. Not only yuzu but also hesperidin inhibited caspase-3 activity, myeloperoxidase expression, α-smooth muscle actin expression, and matrix metalloproteinase-2 activity in a permanent LAD occlusion rat model. To our knowledge, our findings provide the first evidence that yuzu and hesperidin prevent MI-induced ventricular dysfunction and structural remodeling of myocardium. PMID:25559243

  20. Transcriptomics and proteomics analyses of the PACAP38 influenced ischemic brain in permanent middle cerebral artery occlusion model mice

    Directory of Open Access Journals (Sweden)

    Hori Motohide

    2012-11-01

    Full Text Available Abstract Introduction The neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP is considered to be a potential therapeutic agent for prevention of cerebral ischemia. Ischemia is a most common cause of death after heart attack and cancer causing major negative social and economic consequences. This study was designed to investigate the effect of PACAP38 injection intracerebroventrically in a mouse model of permanent middle cerebral artery occlusion (PMCAO along with corresponding SHAM control that used 0.9% saline injection. Methods Ischemic and non-ischemic brain tissues were sampled at 6 and 24 hours post-treatment. Following behavioral analyses to confirm whether the ischemia has occurred, we investigated the genome-wide changes in gene and protein expression using DNA microarray chip (4x44K, Agilent and two-dimensional gel electrophoresis (2-DGE coupled with matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS, respectively. Western blotting and immunofluorescent staining were also used to further examine the identified protein factor. Results Our results revealed numerous changes in the transcriptome of ischemic hemisphere (ipsilateral treated with PACAP38 compared to the saline-injected SHAM control hemisphere (contralateral. Previously known (such as the interleukin family and novel (Gabra6, Crtam genes were identified under PACAP influence. In parallel, 2-DGE analysis revealed a highly expressed protein spot in the ischemic hemisphere that was identified as dihydropyrimidinase-related protein 2 (DPYL2. The DPYL2, also known as Crmp2, is a marker for the axonal growth and nerve development. Interestingly, PACAP treatment slightly increased its abundance (by 2-DGE and immunostaining at 6 h but not at 24 h in the ischemic hemisphere, suggesting PACAP activates neuronal defense mechanism early on. Conclusions This study provides a detailed inventory of PACAP influenced gene expressions

  1. Evaluation of the CritiView in pig model of abdominal aortic occlusion and graded hemorrhage

    Science.gov (United States)

    Mayevsky, A.; Preisman, S.; Willenz, P. E.; Castel, D.; Perel, A.; Givony, D.; Dekel, N.; Oren, L.; Pewzner, E.

    2009-02-01

    We hypothesize that in the presence of reduced oxygen delivery and extraction, blood flow will be redistributed in order to protect the most vital organs (e.g., brain and heart) by increasing their regional blood flow, while O2 delivery to the less vital organs (e.g., GI tract or urethral wall) will diminish. Evaluation of mitochondrial function in vivo could be done by monitoring the oxidation reduction state of the respiratory chain. Thus, the NADH redox state of less vital organs could serve as an indicator of overall O2 imbalance as well as an endpoint of resuscitation. We have therefore tested, in a pig model, a new medical device providing real time data on NADH redox state and tissue blood flow- TBF This device contains a modified three way Foley catheter with a fiber optic probe which connects the measurement unit to the tested tissue. Female pigs underwent graded hemorrhage (GH) or Aortic clamping (AC). The main effects of GH started when blood volume decreased by 30%. At 40% blood loss, minimal levels of TBF were correlated to the maximal NADH levels. The values of the 2 parameters returned to baseline after retransfusion of the shed blood. Aortic clamping led to significant decrease in TBF while NADH levels increased. After aortic declamping the parameters recovered to normal values. Due to the short length of the urethra in female pigs and the instable contact between the probe and the tissue, inconsistency of the responses was observed. Our preliminary results show that the CritiView may be a useful tool for the detection of body O2 imbalance.

  2. An engineering analysis of dental occlusion principles.

    Science.gov (United States)

    Katona, Thomas R

    2009-06-01

    The purpose of this study was to develop an analytical model of contacting teeth, based on principles of basic engineering statics. The model would be used to demonstrate the interactions between occlusal contacts and tooth loading (forces and moments) and to critique occlusion-related dogma. Free-body diagrams were drawn to depict 2 teeth in occlusal contact. In combination with the concept of the center of resistance, the governing equilibrium equations were derived and used to solve for the forces and moments on the teeth and to investigate the influences of tripod and cusp-fossa occlusal schemes. With a specific load on a tooth, it was demonstrated that the load on the opposing tooth and the concomitant occlusal scheme dictated crown-crown contact forces that can be computed. This engineering analysis suggests flaws in widely held notions about the mechanics of occlusion. Loading that is generally considered clinically desirable is certain to produce undesirable loading on the opposing tooth. The complex relationships between the loads on teeth and crown-crown occlusal contacts make it virtually impossible to control tooth loading with occlusal equilibration. For computational and conceptual reasons, it is essential to consider the center of resistance.

  3. Effect of different lateral occlusion schemes on peri-implant strain: A laboratory study

    OpenAIRE

    Lo, Jennifer; ABDUO, Jaafar; Palamara, Joseph

    2017-01-01

    PURPOSE This study aims to investigate the effects of four different lateral occlusion schemes and different excursions on peri-implant strains of a maxillary canine implant. MATERIALS AND METHODS Four metal crowns with different occlusion schemes were attached to an implant in the maxillary canine region of a resin model. The included schemes were canine-guided (CG) occlusion, group function (GF) occlusion, long centric (LC) occlusion, and implant-protected (IP) occlusion. Each crown was loa...

  4. Efficacy of occlusion of hepatic artery and risk of carbon dioxide gas embolism during laparoscopic hepatectomy in a pig model.

    Science.gov (United States)

    Makabe, Kenji; Nitta, Hiroyuki; Takahara, Takeshi; Hasegawa, Yasushi; Kanno, Shoji; Nishizuka, Satoshi; Sasaki, Akira; Wakabayashi, Go

    2014-08-01

    The important point in safely performing laparoscopic hepatectomy (LH) is to control bleeding. The aims of this study were: (i) to assess the bleeding reduction effect by occlusion of the hepatic artery in LH; and (ii) to evaluate the risk of carbon dioxide (CO2 ) gas embolism (GE) in the case of high pneumoperitoneum (PP). Nine piglets underwent laparoscopic left medial lobe and left lateral lobe resection, receiving either occlusion of the hepatic artery (hepatic artery clamping group: HACG, n = 9) or no occlusion (hepatic artery declamping group: HADCG, n = 9) using a PP of 15 mmHg. In addition, we observed changes in hemodynamics induced by PP. The state of GE was observed using transesophageal echocardiography (TEE) during LH (n = 8). GE was graded as grade 0 (none), grade 1 (minor), and grade 2 (major). The HACG had significantly less bleeding compared to the HADCG (P < 0.01). During LH, four animals showed grade 1 (37.5%) and one animal showed grade 2 (12.5%) GE at 15 mmHg. At 20 mmHg, all animals showed grade 2 (100%) GE. The occlusion of the hepatic artery in LH reduces blood loss. The control of bleeding from the hepatic vein is feasible with a high PP, but there is a possibility of GE. © 2014 Japanese Society of Hepato-Biliary-Pancreatic Surgery.

  5. SURROGATE MODEL DEVELOPMENT AND VALIDATION FOR RELIABILITY ANALYSIS OF REACTOR PRESSURE VESSELS

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, William M.; Riley, Matthew E.; Spencer, Benjamin W.

    2016-07-01

    In nuclear light water reactors (LWRs), the reactor coolant, core and shroud are contained within a massive, thick walled steel vessel known as a reactor pressure vessel (RPV). Given the tremendous size of these structures, RPVs typically contain a large population of pre-existing flaws introduced in the manufacturing process. After many years of operation, irradiation-induced embrittlement makes these vessels increasingly susceptible to fracture initiation at the locations of the pre-existing flaws. Because of the uncertainty in the loading conditions, flaw characteristics and material properties, probabilistic methods are widely accepted and used in assessing RPV integrity. The Fracture Analysis of Vessels – Oak Ridge (FAVOR) computer program developed by researchers at Oak Ridge National Laboratory is widely used for this purpose. This program can be used in order to perform deterministic and probabilistic risk-informed analyses of the structural integrity of an RPV subjected to a range of thermal-hydraulic events. FAVOR uses a one-dimensional representation of the global response of the RPV, which is appropriate for the beltline region, which experiences the most embrittlement, and employs an influence coefficient technique to rapidly compute stress intensity factors for axis-aligned surface-breaking flaws. The Grizzly code is currently under development at Idaho National Laboratory (INL) to be used as a general multiphysics simulation tool to study a variety of degradation mechanisms in nuclear power plant components. The first application of Grizzly has been to study fracture in embrittled RPVs. Grizzly can be used to model the thermo-mechanical response of an RPV under transient conditions observed in a pressurized thermal shock (PTS) scenario. The global response of the vessel provides boundary conditions for local 3D models of the material in the vicinity of a flaw. Fracture domain integrals are computed to obtain stress intensity factors, which can in

  6. A Comparison of Various Stress Rupture Life Models for Orbiter Composite Pressure Vessels and Confidence Intervals

    Science.gov (United States)

    Grimes-Ledesma, Lorie; Murthy, Pappu L. N.; Phoenix, S. Leigh; Glaser, Ronald

    2007-01-01

    In conjunction with a recent NASA Engineering and Safety Center (NESC) investigation of flight worthiness of Kevlar Overwrapped Composite Pressure Vessels (COPVs) on board the Orbiter, two stress rupture life prediction models were proposed independently by Phoenix and by Glaser. In this paper, the use of these models to determine the system reliability of 24 COPVs currently in service on board the Orbiter is discussed. The models are briefly described, compared to each other, and model parameters and parameter uncertainties are also reviewed to understand confidence in reliability estimation as well as the sensitivities of these parameters in influencing overall predicted reliability levels. Differences and similarities in the various models will be compared via stress rupture reliability curves (stress ratio vs. lifetime plots). Also outlined will be the differences in the underlying model premises, and predictive outcomes. Sources of error and sensitivities in the models will be examined and discussed based on sensitivity analysis and confidence interval determination. Confidence interval results and their implications will be discussed for the models by Phoenix and Glaser.

  7. Mathematical Models and Numerical Simulations for the Blood Flow in Large Vessels

    Directory of Open Access Journals (Sweden)

    Titus PETRILA

    2012-12-01

    Full Text Available We are proposing a non-Newtonian, Cross type rheological model for the blood flow, under the conditions of an unsteady flow regime connected with the rhythmic pumping of the blood by the heart. We admit the incompressibility and homogeneity of the blood while its flow is laminar and the exterior body forces are neglected. We take also into account the viscoelastic behavior of the vessel walls. The mathematical equations and the appropriate boundary conditions are considered in cylindrical (axisymmetric coordinates. Numerical experiments in case of stenosed artery and in artery with aneurysm (using COMSOL Multiphysics 3.3 are made. The variation of the wall shear stress, which is believed to have a special importance in the rupture of aneurysms, is calculated using both a Newtonian and a non-Newtonian model.

  8. Numerical study of unsteady blood flow through a vessel using Sisko model

    Directory of Open Access Journals (Sweden)

    Akbar Zaman

    2016-03-01

    Full Text Available A mathematical study for two-phase unsteady pulsatile flow of blood through a vessel in the presence of body acceleration is presented in this paper. The blood in the core region is modeled as a non-Newtonian fluid while in the peripheral region it is described as a Newtonian fluid. The effects of body acceleration are also taken into account in this study. The continuity and momentum equations are used to model the proposed problem in terms of a nonlinear partial differential equation. This equation along with initial and boundary conditions is made dimensionless and then solved numerically using finite difference method. The behavior of various flow quantitates is analyzed through a parametric study.

  9. Demarcation of inland vessels' limit off Mormugao port region, India: A pilot study for the safety of inland vessels using wave modelling

    Digital Repository Service at National Institute of Oceanography (India)

    Vethamony, P.; Aboobacker, V.M.; Sudheesh, K.; Babu, M.T.; AshokKumar, A.

    The Ministry of Shipping desires to revise the inland vessels' limit (IVL) notification based on scientific rationale to improve the safety of vessels and onboard personnel. The Mormugao port region extending up to the Panaji was considered...

  10. Streaming flow from ultrasound contrast agents by acoustic waves in a blood vessel model.

    Science.gov (United States)

    Cho, Eunjin; Chung, Sang Kug; Rhee, Kyehan

    2015-09-01

    To elucidate the effects of streaming flow on ultrasound contrast agent (UCA)-assisted drug delivery, streaming velocity fields from sonicated UCA microbubbles were measured using particle image velocimetry (PIV) in a blood vessel model. At the beginning of ultrasound sonication, the UCA bubbles formed clusters and translated in the direction of the ultrasound field. Bubble cluster formation and translation were faster with 2.25MHz sonication, a frequency close to the resonance frequency of the UCA. Translation of bubble clusters induced streaming jet flow that impinged on the vessel wall, forming symmetric vortices. The maximum streaming velocity was about 60mm/s at 2.25MHz and decreased to 15mm/s at 1.0MHz for the same acoustic pressure amplitude. The effect of the ultrasound frequency on wall shear stress was more noticeable. Maximum wall shear stress decreased from 0.84 to 0.1Pa as the ultrasound frequency decreased from 2.25 to 1.0MHz. The maximum spatial gradient of the wall shear stress also decreased from 1.0 to 0.1Pa/mm. This study showed that streaming flow was induced by bubble cluster formation and translation and was stronger upon sonication by an acoustic wave with a frequency near the UCA resonance frequency. Therefore, the secondary radiant force, which is much stronger at the resonance frequency, should play an important role in UCA-assisted drug delivery. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Simultaneous shape and deformation measurements in a blood vessel model by two wavelength interferometry

    Science.gov (United States)

    Andrés, Nieves; Pinto, Cristina; Lobera, Julia; Palero, Virginia; Arroyo, M. Pilar

    2017-06-01

    Holographic techniques have been used to measure the shape and the radial deformation of a blood vessel model and a real sheep aorta. Measurements are obtained from several holograms recorded for different object states. For each object state, two holograms with two different wavelengths are multiplexed in the same digital recording. Thus both holograms are simultaneously recorded but the information from each of them is separately obtained. The shape analysis gives a wrapped phase map whose fringes are related to a synthetic wavelength. After a filtering and unwrapping process, the 3D shape can be obtained. The shape data for each line are fitted to a circumference in order to determine the local vessel radius and center. The deformation analysis also results in a wrapped phase map, but the fringes are related to the laser wavelength used in the corresponding hologram. After the filtering and unwrapping process, a 2D map of the deformation in an out-of-plane direction is reconstructed. The radial deformation is then calculated by using the shape information.

  12. Atherosclerosis of coronary blood vessels - local or systemic inflamation?

    Science.gov (United States)

    Pejkov, Hristo; Kedev, Sasko; Panov, Saso; Srbinovska-Kostovska, Elizabeta; Lang, Irene

    2013-01-01

    The presence of atherosclerotic lesions in the blood vessels is a predisposition for the development and occurrence of acute ischaemic attacks. Bigger atherosclerotic lesions in the coronary blood vessels cause lumen occlusion, which is a cause of acute myocardial infarction. Endothelial dysfunction is defined as an ability of the endothelium to produce vasorelaxing nitric oxide (NO), or deregulation of the other vasoactive substances, such as angiotensin II and endothelin [13]. This definition describes endothelial dysfunction as an improper vasomotor constriction of the vessel, that leads to lumen occlusion of the already existing atherosclerotic lesions. According to the modern model, the development of atherosclerotic plaque and inappropriate endothelial NO production have a synergistic role in patho-physiological and molecular processes in the blood vessels [14]. Lesions in the coronary arteries are deposits of huge quantities of foamy cells and fibrous plaques. The thin fibrous plaques are 10-20% of the total plaque population and are the cause of 80-90% of clinical cases due to their ability to rupture [48]. According to all the results from published studies by far, it has been pointed out that the plaque stability, not the absolute size influences the rupture potential. Elucidating the risk factors that may modify in the atherogenesis and the consequent atherothrombic effect is the first step to this goal.

  13. Maury Journals - German Vessels

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — German vessels observations, after the 1853 Brussels Conference that set International Maritime Standards, modeled after Maury Marine Standard Observations.

  14. Real-Time Video Surveillance System for Traffic Management with Background Subtraction Using Codebook Model and Occlusion Handling

    Directory of Open Access Journals (Sweden)

    Moutakki Zakaria

    2017-12-01

    Full Text Available The scope of this paper is a video surveillance system constituted of three principal modules, segmentation module, vehicle classification and vehicle counting. The segmentation is based on a background subtraction by using the Codebooks method. This step aims to define the regions of interest associated with vehicles. To classify vehicles in their type, our system uses the histograms of oriented gradient followed by support vector machine. Counting and tracking vehicles will be the last task to be performed. The presence of partial occlusion involves the decrease of the accuracy of vehicle segmentation and classification, which directly impacts the robustness of a video surveillance system. Therefore, a novel method to handle the partial occlusions based on vehicle classification process have developed. The results achieved have shown that the accuracy of vehicle counting and classification exceeds the accuracy measured in some existing systems.

  15. The Effect Of Supraphysiologic Blood Pressure on Traumatic Brain Injury and Proximal Tissue Beds During Resuscitative Balloon Occlusion of the Aorta and Variable Aortic Control in a Porcine Model (Sus scrofa) of Polytrauma.

    Science.gov (United States)

    2017-04-27

    Supraphysiologic Blood Pressure On Traumatic Brain Injury And Proximal Tissue Beds During Resuscitative Balloon Occlusion Of The Aorta And Variable Aortic...Mandatory) The Effect of REBOA, Partial Aortic Occlusion and Aggressive Blood Transfusion on Traumatic Brain Injury in a Swine Polytrauma Model...Objectives: Despite clinical reports of poor outcomes, the degree to which REBOA exacerbates traumatic brain injury (TBI) is not known. We hypothesized that

  16. Alveolarization genes modulated by fetal tracheal occlusion in the rabbit model for congenital diaphragmatic hernia: a randomized study.

    Directory of Open Access Journals (Sweden)

    Aline Vuckovic

    Full Text Available BACKGROUND: The mechanisms by which tracheal occlusion (TO improves alveolarization in congenital diaphragmatic hernia (CDH are incompletely understood. Therefore transcriptional and histological effects of TO on alveolarization were studied in the rabbit model for CDH. The question of the best normalization strategy for gene expression analysis was also addressed. METHODS: Fetal rabbits were randomized for CDH or sham operation on gestational day 23/31 and for TO or sham operation on day 28/31 resulting in four study groups. Untouched littermates were added. At term and before lung harvest, fetuses were subjected to mechanical ventilation or not. Quantitative real-time PCR was performed on lungs from 4-5 fetuses of each group with and without previous ventilation. Stability of ten housekeeping genes (HKGs and optimal number of HKGs for normalization were determined, followed by assessment of HKG expression levels. Expression levels of eleven target genes were studied in ventilated lungs, including genes regulating elastogenesis, cell-environment interactions, and thinning of alveolar walls. Elastic staining, immunohistochemistry and Western blotting completed gene analysis. RESULTS: Regarding HKG expression, TO increased β-actin and β-subunit of ATP synthase. Mechanical ventilation increased β-actin and β2-microglobulin. Flavoprotein subunit of succinate dehydrogenase and DNA topoisomerase were the most stable HKGs. CDH lungs showed disorganized elastin deposition with lower levels for tropoelastin, fibulin-5, tenascin-C, and α6-integrin. After TO, CDH lungs displayed a normal pattern of elastin distribution with increased levels for tropoelastin, fibulin-5, tenascin-C, α6-integrin, ß1-integrin, lysyl oxidase, and drebrin. TO increased transcription and immunoreactivity of tissue inhibitor of metalloproteinase-1. CONCLUSIONS: Experimental TO might improve alveolarization through the mechanoregulation of crucial genes for late lung

  17. Occlusion effects, Part I

    DEFF Research Database (Denmark)

    Hansen, Mie Østergaard

    annoyances and the objective measurements were analysed. Persons suffering from tinnitus behaved differently than person without tinnitus. The latter group showed significant relations between the measured occlusion effect, hearing loss and the personal of occlusion. The actual sensation level is also...

  18. Pregnancy after tubal occlusion

    African Journals Online (AJOL)

    SA MEDIESE TYDSKRIF DEEL 63 2 APRIL 1983. 517. Pregnancy after tubal occlusion. A 5-year study. K. D. GUNSTON, H. A. VAN COEVERDEN DE GROOT, M. R. BROMHALL. Pregnancy after laparoscopy. The various methods oflaparoscopic tubal occlusion employed and the pregnancy rates are listed in Table I.

  19. Occlusion Handling in Videos Object Tracking: A Survey

    Science.gov (United States)

    Lee, B. Y.; Liew, L. H.; Cheah, W. S.; Wang, Y. C.

    2014-02-01

    Object tracking in video has been an active research since for decades. This interest is motivated by numerous applications, such as surveillance, human-computer interaction, and sports event monitoring. Many challenges related to tracking objects still remain, this can arise due to abrupt object motion, changing appearance patterns of objects and the scene, non-rigid object structures and most significant are occlusion of tracked object be it object-to-object or object-to-scene occlusions. Generally, occlusion in object tracking occur under three situations: self-occlusion, inter-object occlusion by background scene structure. Self-occlusion occurs most frequently while tracking articulated objects when one part of the object occludes another. Inter-object occlusion occurs when two objects being tracked occlude each other whereas occlusion by the background occurs when a structure in the background occludes the tracked objects. Typically, tracking methods handle occlusion by modelling the object motion using linear and non-linear dynamic models. The derived models will be used to continuously predicting the object location when a tracked object is occluded until the object reappears. Example of these method are Kalman filtering and Particle filtering trackers. Researchers have also utilised other features to resolved occlusion, for example, silhouette projections, colour histogram and optical flow. We will present some result from a previously conducted experiment when tracking single object using Kalman filter, Particle filter and Mean Shift trackers under various occlusion situation in this paper. We will also review various other occlusion handling methods that involved using multiple cameras. In a nutshell, the goal of this paper is to discuss in detail the problem of occlusion in object tracking and review the state of the art occlusion handling methods, classify them into different categories, and identify new trends. Moreover, we discuss the important

  20. The impact of mobile point defect clusters in a kinetic model of pressure vessel embrittlement

    Energy Technology Data Exchange (ETDEWEB)

    Stoller, R.E.

    1998-05-01

    The results of recent molecular dynamics simulations of displacement cascades in iron indicate that small interstitial clusters may have a very low activation energy for migration, and that their migration is 1-dimensional, rather than 3-dimensional. The mobility of these clusters can have a significant impact on the predictions of radiation damage models, particularly at the relatively low temperatures typical of commercial, light water reactor pressure vessels (RPV) and other out-of-core components. A previously-developed kinetic model used to investigate RPV embrittlement has been modified to permit an evaluation of the mobile interstitial clusters. Sink strengths appropriate to both 1- and 3-dimensional motion of the clusters were evaluated. High cluster mobility leads to a reduction in the amount of predicted embrittlement due to interstitial clusters since they are lost to sinks rather than building up in the microstructure. The sensitivity of the predictions to displacement rate also increases. The magnitude of this effect is somewhat reduced if the migration is 1-dimensional since the corresponding sink strengths are lower than those for 3-dimensional diffusion. The cluster mobility can also affect the evolution of copper-rich precipitates in the model since the radiation-enhanced diffusion coefficient increases due to the lower interstitial cluster sink strength. The overall impact of the modifications to the model is discussed in terms of the major irradiation variables and material parameter uncertainties.

  1. A New Occlusion Device: Application of the ArtVentive Endoluminal Occlusion System (EOS)—First in Human Clinical Trial

    Energy Technology Data Exchange (ETDEWEB)

    Venbrux, Anthony C., E-mail: avenbrux@mfa.gwu.edu [The George Washington University Medical Center, Division of Vascular and Interventional Radiology (United States); Rudakov, Leon, E-mail: leonrudakov@artventivemedical.com [Artventive Medical Group, Inc. (United States); Plass, Andre, E-mail: andre.plass@usz.ch; Emmert, Maximilian Y., E-mail: maximilian.emmert@usz.ch [University Hospital Zurich, Clinic for Cardiac and Vascular Surgery (Switzerland); Ebner, Adrian, E-mail: adrianebner@fundacor.com.py [Sanatorio Privado Santa Clara, Cath Lab Department (Paraguay)

    2013-05-24

    PurposeThe purpose of this study was to determine the safety and efficacy of a new endoluminal occlusion device, ArtVentive endoluminal occlusion system (EOS), to occlude the spermatic vein in symptomatic males with varicoceles.MethodsThe ArtVentive EOS device has been developed for percutaneous, peripheral occlusion of the peripheral arterial and venous vasculature. The system is comprised of an implantable occlusion device and a delivery catheter. At present, there are two device sizes: (a) size 1 for target vessels ranging between 3.5 and 5.5 mm in diameter, and (b) size 2 for target vessels 5.5–8.5 mm in diameter. The treatment group included six adult males, ages 22–34 years. Nine target vessels were occluded. A total of 20 devices were implanted in six subjects.ResultsThe acute occlusion rate at the end of the procedure was 100 % occurring in nine of nine vessels. The spermatic veins of all patients remained occluded on venography at 30 days follow-up. Pain scores related to varicoceles decreased in five of six patients.ConclusionsAlthough we recognize this study is limited, initial experience indicates that the ArtVentive EOS is a safe and effective new device for occlusion of vessels (varicoceles). The device has potential applications in other clinical conditions requiring occlusion of veins or arteries.

  2. A Constraint Programming Model for Fast Optimal Stowage of Container Vessel Bays

    DEFF Research Database (Denmark)

    Delgado-Ortegon, Alberto; Jensen, Rune Møller; Janstrup, Kira

    2012-01-01

    Container vessel stowage planning is a hard combinatorial optimization problem with both high economic and environmental impact. We have developed an approach that often is able to generate near-optimal plans for large container vessels within a few minutes. It decomposes the problem into a maste...

  3. A Stefan model for mass transfer in a rotating disk reaction vessel

    KAUST Repository

    BOHUN, C. S.

    2015-05-04

    Copyright © Cambridge University Press 2015. In this paper, we focus on the process of mass transfer in the rotating disk apparatus formulated as a Stefan problem with consideration given to both the hydrodynamics of the process and the specific chemical reactions occurring in the bulk. The wide range in the reaction rates of the underlying chemistry allows for a natural decoupling of the problem into a simplified set of weakly coupled convective-reaction-diffusion equations for the slowly reacting chemical species and a set of algebraic relations for the species that react rapidly. An analysis of the chemical equilibrium conditions identifies an expansion parameter and a reduced model that remains valid for arbitrarily large times. Numerical solutions of the model are compared to an asymptotic analysis revealing three distinct time scales and chemical diffusion boundary layer that lies completely inside the hydrodynamic layer. Formulated as a Stefan problem, the model generalizes the work of Levich (Levich and Spalding (1962) Physicochemical hydrodynamics, vol. 689, Prentice-Hall Englewood Cliffs, NJ) and will help better understand the natural limitations of the rotating disk reaction vessel when consideration is made for the reacting chemical species.

  4. Follicular occlusion tetrad

    Directory of Open Access Journals (Sweden)

    Vani Vasanth

    2014-01-01

    Full Text Available Follicular occlusion tetrad is a symptom complex consisting of four conditions having a similar pathophysiology. It includes Hidradenitis suppurativa, acne conglobata, dissecting cellulitis of the scalp and pilonidal sinus. The exact pathogenesis of this group of disease is unknown but evidence suggests that they share the same pathological process initiated by follicular occlusion in apocrine gland bearing areas. Though each of these conditions is commonly encountered singly, follicular occlusion tetrad as a symptom complex has been rarely reported in the literature.

  5. Models for embrittlement recovery due to annealing of reactor pressure vessel steels

    Energy Technology Data Exchange (ETDEWEB)

    Eason, E.D.; Wright, J.E.; Nelson, E.E. [Modeling and Computing Services, Boulder, CO (United States); Odette, G.R.; Mader, E.V. [California Univ., Santa Barbara, CA (United States)

    1995-05-01

    The reactor pressure vessel (RPV) surrounding the core of a commercial nuclear power plant is subject to embrittlement due to exposure to high energy neutrons. The effects of irradiation embrittlement can be reduced by thermal annealing at temperatures higher than the normal operating conditions. However, a means of quantitatively assessing the effectiveness of annealing for embrittlement recovery is needed. The objective of this work was to analyze the pertinent data on this issue and develop quantitative models for estimating the recovery in 30 ft-lb (41 J) Charpy transition temperature and Charpy upper shelf energy due to annealing. Data were gathered from the Test Reactor Embrittlement Data Base and from various annealing reports. An analysis data base was developed, reviewed for completeness and accuracy, and documented as part of this work. Independent variables considered in the analysis included material chemistries, annealing time and temperature, irradiation time and temperature, fluence, and flux. To identify important variables and functional forms for predicting embrittlement recovery, advanced statistical techniques, including pattern recognition and transformation analysis, were applied together with current understanding of the mechanisms governing embrittlement and recovery. Models were calibrated using multivariable surface-fitting techniques. Several iterations of model calibration, evaluation with respect to mechanistic and statistical considerations, and comparison with the trends in hardness data produced correlation models for estimating Charpy upper shelf energy and transition temperature after irradiation and annealing. This work provides a clear demonstration that (1) microhardness recovery is generally a very good surrogate for shift recovery, and (2) there is a high level of consistency between the observed annealing trends and fundamental models of embrittlement and recovery processes.

  6. Modeling and simulation of the bubble-induced flow in wine fermentation vessels

    Directory of Open Access Journals (Sweden)

    Schmidt Dominik

    2015-01-01

    Full Text Available Detailed flow pattern analyses regarding wine fermentations conducted without mechanical agitation are limited to lab-scale investigations, as industrial size measurements are expensive and difficult to realize. Computational fluid dynamic (CFD methods can offer an alternative and more flexible approach to gain insight into such bubble induced fluid flows. Therefore, the aim of this study was to transfer the findings of existing research onto a CFD model capable of capturing the three- dimensional flow pattern in industrial scale wine fermentation vessels. First results were obtained by using an extended version of the OpenFOAM® (v.2.2.x solver multiphaseEulerFoam for modeling the gas-liquid two phase system. With parameters from the most vigorous phase of wine fermentation a fully developed, unsteady flow regime could be established after approx. 120 s of real time. Thereby the groundwork for further evaluations of e.g. mixing efficiency or cooling equipment optimizations with CFD methods is laid.

  7. Modeling the color perception of port wine stains and its relation to the depth of laser coagulated blood vessels

    NARCIS (Netherlands)

    Lakmaker, O.; Pickering, J. W.; van Gemert, M. J.

    1993-01-01

    To find the maximal depth of an ecstatic vessel in the dermis that contributes to the abnormal color of a port wine stain (PWS), "normal" and "laser treated PWS skin" are modeled, respectively, as a two-layer plane parallel geometry consisting of an epidermis and a dermis, and as a three-layer

  8. Short time effects of radiotherapy on lymphatic vessels and restorative lymphatic pathways: experimental approaches ina mouse model.

    Science.gov (United States)

    Pastouret, F; Lievens, P; Leduc, O; Bourgeois, P; Tournel, K; Lamote, J; Zirak, C; Leduc, A

    2014-06-01

    Radiotherapy (RT) is an important component in the therapeutic approach to oncologic conditions. This study presents the investigative results on the impact of RT on lymphatic vessels and on the regenerative response of the lymphatic system in a mouse model. We first irradiated 3 groups of ten mice using brachytherapy in a single treatment of 20 Gy. We then performed morphological examination of the irradiated lymphatic vessels using an in vivo microscopic transillumination technique at 2, 4, and 6 weeks. Next we evaluated lymphatic flow using lymphoscintigraphy and in vivo microscopy at 6 to 11 weeks in: 10 additional mice following irradiation as above (IR), in 10 mice following incision of a lymphatic vessel (I), and in a non-treated control group of 10 mice (N). Intact lymphatic vessels were observed in all mice at 2, 4, and 8 weeks following the single dose of radiotherapy in the first group of mice and normal lymphatic flow was fully restored in the irradiated (IR) and incised (I) mice indicating that the reparative substitution lymphatic pathways are functioning normally. We found that following irradiation with one dose of 20 Gy, lymphatic vessels were not visibly damaged and also that lymphatic flow was consistently restored and substitutive lymphatic pathways formed.

  9. Bioabsorbable radiopaque water-responsive shape memory embolization plug for temporary vascular occlusion.

    Science.gov (United States)

    Wong, Yee Shan; Salvekar, Abhijit Vijay; Zhuang, Kun Da; Liu, Hui; Birch, William R; Tay, Kiang Hiong; Huang, Wei Min; Venkatraman, Subbu S

    2016-09-01

    We describe the preparation, characterization and evaluation of a biodegradable radiopaque water-triggered shape memory embolization plug for temporary vascular occlusion. The shape memory occluding device consists of a composite of a radio-opaque filler and a poly (dl-lactide-co-glycolide) (PLGA) blend, which was coated with a crosslinked poly (ethylene glycol) diacrylate (PEGDA) hydrogel. The mechanical properties, the degradation timeframe, the effect of programming conditions on the shape memory behaviour and the extent of radio-opacity for imaging were evaluated. Based on the tests, the mechanism responsible for the water-induced shape memory effect in such an embolization plug was elucidated. Suitable materials were optimized to fabricate an embolic plug prototype and its in vitro performance was evaluated as an occlusion rate (using a custom-built set up) and its biocompatibility. Finally, a feasibility study was conducted in vivo in a rabbit model to investigate the ease of device deployment, device migration and extent of vessel occlusion. The in vivo results demonstrated that the prototypes were visible under fluoroscopy and complete vascular occlusion occurred within 2 min of deployment of the prototypes in vivo. In conclusion, the developed embolization plug enables controlled and temporary vascular embolization, and is ready for safety studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Cerebral blood flow reduction in Alzheimer's disease: impact of capillary occlusions on mice and humans

    Science.gov (United States)

    Berg, Maxime; Merlo, Adlan; Peyrounette, Myriam; Doyeux, Vincent; Smith, Amy; Cruz-Hernandez, Jean; Bracko, Oliver; Haft-Javaherian, Mohammad; Nishimura, Nozomi; Schaffer, Chris B.; Davit, Yohan; Quintard, Michel; Lorthois, Sylvie

    2017-11-01

    Alzheimer's disease may be the most common form of dementia, yet a satisfactory diagnosis procedure has still to be found. Recent studies suggest that a significant decrease of cerebral blood flow, probably caused by white blood cells stalling small vessels, may be among the earliest biological markers. To assess this hypothesis we derive a blood flow model, validate it against in vitro controlled experiments and in vivo measurements made on mice. We then investigate the influence of capillary occlusions on regional perfusion (sum of all arteriole flowrates feeding the network) of large mice and humans anatomical networks. Consistent with experiments, we observe no threshold effect, so that even a small percentage of occlusions (2-4%) leads to significant blood flow decrease (5-12%). We show that both species share the same linear dependance, suggesting possible translation from mice to human. ERC BrainMicroFlow GA61510, CALMIP HPC (Grant 2017-1541).

  11. Bilateral uterine vessel ligation as a model of intrauterine growth restriction in mice

    Science.gov (United States)

    2014-01-01

    Background Intrauterine Growth Restriction (IUGR) occurs in up to 10% of pregnancies and is considered as a major risk to develop various diseases in adulthood, such as cardiovascular diseases, insulin resistance, hypertension or end stage kidney disease. Several IUGR models have been developed in order to understand the biological processes linked to fetal growth retardation, most of them being rat or mouse models and nutritional models. In order to reproduce altered placental flow, surgical models have also been developed, and among them bilateral uterine ligation has been frequently used. Nevertheless, this model has never been developed in the mouse, although murine tools display multiple advantages for biological research. The aim of this work was therefore to develop a mouse model of bilateral uterine ligation as a surgical model of IUGR. Results In this report, we describe the set up and experimental data obtained from three different protocols (P1, P2, P3) of bilateral uterine vessel ligation in the mouse. Ligation was either performed at the cervical end of each uterine horn (P1) or at the central part of each uterine horn (P2 and P3). Time of surgery was E16 (P1), E17 (P2) or E16.5 (P3). Mortality, maternal weight and abortion parameters were recorded, as well as placentas weights, fetal resorption, viability, fetal weight and size. Results showed that P1 in test animals led to IUGR but was also accompanied with high mortality rate of mothers (50%), low viability of fetuses (8%) and high resorption rate (25%). P2 and P3 improved most of these parameters (decreased mortality and improved pregnancy outcomes; improved fetal viability to 90% and 27%, respectively) nevertheless P2 was not associated to IUGR contrary to P3. Thus P3 experimental conditions enable IUGR with better pregnancy and fetuses outcomes parameters that allow its use in experimental studies. Conclusions Our results show that bilateral uterine artery ligation according to the protocol we

  12. Towards the Development of a Risk Model for Unmanned Vessels Design and Operations

    Directory of Open Access Journals (Sweden)

    Krzysztof Wrobel

    2016-07-01

    Full Text Available An unmanned merchant vessel seems to be escaping from the stage of idea exploration. Once the concept proofs its safety, it may become a part of maritime reality. Although the safety aspect of such a ship has been addressed by a handful of scholars, the problem remains open. This is mainly due to lack of knowledge regarding actual operational circumstances and design of unmanned ships, which are yet to be developed. In the attempt of bridging this gap, the risk analysis associated with unmanned ships needs to be carried out, where all relevant hazards and consequences are assessed and quantified in systematic manner. In this paper we present the results of a first step of such analysis, namely the hazard analysis associated with the unmanned ships. The list of hazards covers various aspects of unmanned shipping originating from both design and operational phases of vessel’s life. Subsequently the hazards and related consequences are organized in a casual manner, resulting in the development of a structure of a risk model.

  13. Suitability of pharmacokinetic models for dynamic contrast-enhanced MRI of abdominal aortic aneurysm vessel wall: a comparison.

    Directory of Open Access Journals (Sweden)

    V Lai Nguyen

    Full Text Available PURPOSE: Increased microvascularization of the abdominal aortic aneurysm (AAA vessel wall has been related to AAA progression and rupture. The aim of this study was to compare the suitability of three pharmacokinetic models to describe AAA vessel wall enhancement using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI. MATERIALS AND METHODS: Patients with AAA underwent DCE-MRI at 1.5 Tesla. The volume transfer constant (K(trans , which reflects microvascular flow, permeability and surface area, was calculated by fitting the blood and aneurysm vessel wall gadolinium concentration curves. The relative fit errors, parameter uncertainties and parameter reproducibilities for the Patlak, Tofts and Extended Tofts model were compared to find the most suitable model. Scan-rescan reproducibility was assessed using the interclass correlation coefficient and coefficient of variation (CV. Further, the relationship between K(trans and AAA size was investigated. RESULTS: DCE-MRI examinations from thirty-nine patients (mean age±SD: 72±6 years; M/F: 35/4 with an mean AAA maximal diameter of 49±6 mm could be included for pharmacokinetic analysis. Relative fit uncertainties for K(trans based on the Patlak model (17% were significantly lower compared to the Tofts (37% and Extended Tofts model (42% (p<0.001. K(trans scan-rescan reproducibility for the Patlak model (ICC = 0.61 and CV = 22% was comparable with the Tofts (ICC = 0.61, CV = 23% and Extended Tofts model (ICC = 0.76, CV = 22%. K(trans was positively correlated with maximal AAA diameter (Spearman's ρ = 0.38, p = 0.02 using the Patlak model. CONCLUSION: Using the presented imaging protocol, the Patlak model is most suited to describe DCE-MRI data of the AAA vessel wall with good K(trans scan-rescan reproducibility.

  14. An Ultrasound Simulation Model for the Pulsatile Blood Flow Modulated by the Motion of Stenosed Vessel Wall.

    Science.gov (United States)

    Zhang, Qinghui; Zhang, Yufeng; Zhou, Yi; Zhang, Kun; Zhang, Kexin; Gao, Lian

    2016-01-01

    This paper presents an ultrasound simulation model for pulsatile blood flow, modulated by the motion of a stenosed vessel wall. It aims at generating more realistic ultrasonic signals to provide an environment for evaluating ultrasound signal processing and imaging and a framework for investigating the behaviors of blood flow field modulated by wall motion. This model takes into account fluid-structure interaction, blood pulsatility, stenosis of the vessel, and arterial wall movement caused by surrounding tissue's motion. The axial and radial velocity distributions of blood and the displacement of vessel wall are calculated by solving coupled Navier-Stokes and wall equations. With these obtained values, we made several different phantoms by treating blood and the vessel wall as a group of point scatterers. Then, ultrasound echoed signals from oscillating wall and blood in the axisymmetric stenotic-carotid arteries were computed by ultrasound simulation software, Field II. The results show better consistency with corresponding theoretical values and clinical data and reflect the influence of wall movement on the flow field. It can serve as an effective tool not only for investigating the behavior of blood flow field modulated by wall motion but also for quantitative or qualitative evaluation of new ultrasound imaging technology and estimation method of blood velocity.

  15. Catheter-Directed Intra-Arterial Abciximab Administration for Acute Thrombotic Occlusions during Neurointerventional Procedures

    OpenAIRE

    Duncan, I.C.; Fourie, P.A.

    2002-01-01

    Abciximab is one of a new class of platelet aggregation inhibitors that has to date been used mainly in the management of acute coronary ischaemic syndromes or during cardiac intervention for the prevention and treatment of acute vessel occlusion during and after angioplasty or stent placement. More recently, it has begun to play a similar role in neurointerventional work. Its administration during acute stent or vessel occlusions has usually been via systemic intravenous infusion. We describ...

  16. Occlusion of the circle of Willis. Diagnosis by 3D-time of flight MR angiography

    Energy Technology Data Exchange (ETDEWEB)

    Komatsumoto, Satoru; Ushioda, Takakazu; Nara, Masaharu [Ashikaga Red Cross Hospital, Tochigi (Japan)

    1996-08-01

    Magnetic resonance angiograms (MRA) were studied in 7 cases of occlusion of the circle of Willis. MRA successfully demonstrated the vascular obstructions and moyamoya vessels with a positive correlation to the angiographic findings. Leptomeningeal and transdural collateral vessels were also identified with MRA. As MRA is not invasive, it promises to become a valuable alternature to conventional angiography in the diagnosis of occlusion of the circle of Willis. (author)

  17. A physical model of laser-assisted blocking of blood flow: I. Rectangular radiation pulses

    CSIR Research Space (South Africa)

    Zheltov, GI

    2007-03-01

    Full Text Available A method for the calculation of blocking of blood flow upon treatment of vessel pathologies by laser irradiation at a wavelength of 530 nm are considered. The model is based on the assumption that blood-vessel occlusion is a consequence of preceding...

  18. Podoplanin immunopositive lymphatic vessels at the implant interface in a rat model of osteoporotic fractures.

    Science.gov (United States)

    Lips, Katrin Susanne; Kauschke, Vivien; Hartmann, Sonja; Thormann, Ulrich; Ray, Seemun; Kampschulte, Marian; Langheinrich, Alexander; Schumacher, Matthias; Gelinsky, Michael; Heinemann, Sascha; Hanke, Thomas; Kautz, Armin R; Schnabelrauch, Matthias; Schnettler, Reinhard; Heiss, Christian; Alt, Volker; Kilian, Olaf

    2013-01-01

    Insertion of bone substitution materials accelerates healing of osteoporotic fractures. Biodegradable materials are preferred for application in osteoporotic patients to avoid a second surgery for implant replacement. Degraded implant fragments are often absorbed by macrophages that are removed from the fracture side via passage through veins or lymphatic vessels. We investigated if lymphatic vessels occur in osteoporotic bone defects and whether they are regulated by the use of different materials. To address this issue osteoporosis was induced in rats using the classical method of bilateral ovariectomy and additional calcium and vitamin deficient diet. In addition, wedge-shaped defects of 3, 4, or 5 mm were generated in the distal metaphyseal area of femur via osteotomy. The 4 mm defects were subsequently used for implantation studies where bone substitution materials of calcium phosphate cement, composites of collagen and silica, and iron foams with interconnecting pores were inserted. Different materials were partly additionally functionalized by strontium or bisphosphonate whose positive effects in osteoporosis treatment are well known. The lymphatic vessels were identified by immunohistochemistry using an antibody against podoplanin. Podoplanin immunopositive lymphatic vessels were detected in the granulation tissue filling the fracture gap, surrounding the implant and growing into the iron foam through its interconnected pores. Significant more lymphatic capillaries were counted at the implant interface of composite, strontium and bisphosphonate functionalized iron foam. A significant increase was also observed in the number of lymphatics situated in the pores of strontium coated iron foam. In conclusion, our results indicate the occurrence of lymphatic vessels in osteoporotic bone. Our results show that lymphatic vessels are localized at the implant interface and in the fracture gap where they might be involved in the removal of lymphocytes, macrophages

  19. Podoplanin immunopositive lymphatic vessels at the implant interface in a rat model of osteoporotic fractures.

    Directory of Open Access Journals (Sweden)

    Katrin Susanne Lips

    Full Text Available Insertion of bone substitution materials accelerates healing of osteoporotic fractures. Biodegradable materials are preferred for application in osteoporotic patients to avoid a second surgery for implant replacement. Degraded implant fragments are often absorbed by macrophages that are removed from the fracture side via passage through veins or lymphatic vessels. We investigated if lymphatic vessels occur in osteoporotic bone defects and whether they are regulated by the use of different materials. To address this issue osteoporosis was induced in rats using the classical method of bilateral ovariectomy and additional calcium and vitamin deficient diet. In addition, wedge-shaped defects of 3, 4, or 5 mm were generated in the distal metaphyseal area of femur via osteotomy. The 4 mm defects were subsequently used for implantation studies where bone substitution materials of calcium phosphate cement, composites of collagen and silica, and iron foams with interconnecting pores were inserted. Different materials were partly additionally functionalized by strontium or bisphosphonate whose positive effects in osteoporosis treatment are well known. The lymphatic vessels were identified by immunohistochemistry using an antibody against podoplanin. Podoplanin immunopositive lymphatic vessels were detected in the granulation tissue filling the fracture gap, surrounding the implant and growing into the iron foam through its interconnected pores. Significant more lymphatic capillaries were counted at the implant interface of composite, strontium and bisphosphonate functionalized iron foam. A significant increase was also observed in the number of lymphatics situated in the pores of strontium coated iron foam. In conclusion, our results indicate the occurrence of lymphatic vessels in osteoporotic bone. Our results show that lymphatic vessels are localized at the implant interface and in the fracture gap where they might be involved in the removal of

  20. Numerical modeling of the pulse wave propagation in large blood vessels based on liquid and wall interaction

    Science.gov (United States)

    Rup, K.; Dróżdż, A.

    2014-08-01

    The purpose of this article is to develop a non-linear, one-dimensional model of pulse wave propagation in the arterial cardiovascular system. The model includes partial differential equations resulting from the balance of mass and momentum for the fluid-filled area and the balance equation for the area of the wall and vessels. The considered mathematical model of pulse wave propagation in the thoracic aorta section takes into account the viscous dissipation of fluid energy, realistic values of parameters describing the physicochemical properties of blood and vessel wall. Boundary and initial conditions contain the appropriate information obtained from in vivo measurements. As a result of the numerical solution of the mass and momentum balance equations for the blood and the equilibrium equation for the arterial wall area, time- dependent deformation, respective velocity profiles and blood pressure were determined.

  1. Protective Effect of Ethanol Extracts of the Chinese Caterpillar Mushroom, Ophiocordyceps sinensis (Ascomycetes), on the Experimental Middle Cerebral Artery Occlusion/Reperfusion (MCAO/R) Model.

    Science.gov (United States)

    Kong, Ran; Zhang, Ying; Zhang, Shuofeng; Liu, Min; Sun, Wenyan; Xing, Yue; Guan, Yalan; Han, Chunchao; Liu, Zhenquan

    2015-01-01

    In this study, we investigated the effects of ethanol extracts of Ophiocordyceps sinensis (EEOS) on neuroprotective efficacy in a rat model of focal cerebral ischemia/reperfusion (IR). The effects of EEOS on mortality rate, neurobehavior, grip strength, polymorphonuclear (PMN) cells, interleukin (IL)-1β, inducible nitric oxide synthase (iNOS), tumor necrosis factor (TNF)-α, intracellular adhesion molecule 1 (ICAM-1), and cyclooxygenase-2 (COX-2) were determined by enzyme-linked immunosorbent assay and immunohistochemistry. The cerebral infarction was examined through tetrazolium chloride staining. EEOS significantly inhibited IR-induced brain production of IL-1β, TNF-α, iNOS, ICAM-1, and COX-2. Moreover, EEOS suppressed infiltration of PMN cells. EEOS caused a significant reduction in the infarct size compared with the middle cerebral artery occlusion group. The study demonstrates the neuroprotective potential of EEOS inhibition of IR through anti-inflammatory activity in a rat model of IR.

  2. Porcine In Vivo Validation of a Virtual Contrast Model: The Influence of Contrast Agent Properties and Vessel Flow Rates.

    Science.gov (United States)

    Peach, T W; Ventikos, Y; Byrne, J V; You, Z

    2016-12-01

    Accurately and efficiently modeling the transport of angiographic contrast currently offers the best method of verifying computational fluid dynamics simulations and, with it, progress toward the lofty goal of prediction of aneurysm treatment outcome a priori. This study specifically examines the influence of estimated flow rate and contrast properties on such in silico predictions of aneurysm contrast residence and decay. Four experimental sidewall aneurysms were created in swine, with aneurysm contrast flow patterns and decay rates observed under angiography. A simplified computational fluid dynamics model of the experimental aneurysm was constructed from 3D angiography and contrast residence predicted a priori. The relative influence of a number of estimated model parameters (contrast viscosity, contrast density, and blood flow rate) on contrast residence was then investigated with further simulations. Contrast infiltration and washout pattern were accurately predicted by the a priori computational fluid dynamics model; however, the contrast decay rate was underestimated by ∼25%. This error was attributed to the estimated parent vessel flow rate alone, and the effects of contrast viscosity and density on the decay rate were found to be inconsequential. A linear correlation between the parent vessel flow rate and the corresponding contrast decay rate was observed. In experimental sidewall aneurysms, contrast fluid properties (viscosity and density) were shown to have a negligible effect on variation in the modeled contrast decay rate. A strong linear correlation was observed between parent vessel flow rate and contrast decay over a physiologically reasonable range of flow rates. © 2016 by American Journal of Neuroradiology.

  3. Radiotherapy and chemotherapy change vessel tree geometry and metastatic spread in a small cell lung cancer xenograft mouse tumor model.

    Directory of Open Access Journals (Sweden)

    Thorsten Frenzel

    Full Text Available Tumor vasculature is critical for tumor growth, formation of distant metastases and efficiency of radio- and chemotherapy treatments. However, how the vasculature itself is affected during cancer treatment regarding to the metastatic behavior has not been thoroughly investigated. Therefore, the aim of this study was to analyze the influence of hypofractionated radiotherapy and cisplatin chemotherapy on vessel tree geometry and metastasis formation in a small cell lung cancer xenograft mouse tumor model to investigate the spread of malignant cells during different treatments modalities.The biological data gained during these experiments were fed into our previously developed computer model "Cancer and Treatment Simulation Tool" (CaTSiT to model the growth of the primary tumor, its metastatic deposit and also the influence on different therapies. Furthermore, we performed quantitative histology analyses to verify our predictions in xenograft mouse tumor model.According to the computer simulation the number of cells engrafting must vary considerably to explain the different weights of the primary tumor at the end of the experiment. Once a primary tumor is established, the fractal dimension of its vasculature correlates with the tumor size. Furthermore, the fractal dimension of the tumor vasculature changes during treatment, indicating that the therapy affects the blood vessels' geometry. We corroborated these findings with a quantitative histological analysis showing that the blood vessel density is depleted during radiotherapy and cisplatin chemotherapy. The CaTSiT computer model reveals that chemotherapy influences the tumor's therapeutic susceptibility and its metastatic spreading behavior.Using a system biological approach in combination with xenograft models and computer simulations revealed that the usage of chemotherapy and radiation therapy determines the spreading behavior by changing the blood vessel geometry of the primary tumor.

  4. Application of photogrammetry for analysis of occlusal contacts.

    Science.gov (United States)

    Shigeta, Yuko; Hirabayashi, Rio; Ikawa, Tomoko; Kihara, Takuya; Ando, Eriko; Hirai, Shinya; Fukushima, Shunji; Ogawa, Takumi

    2013-04-01

    The conventional 2D-analysis methods for occlusal contacts provided limited information on tooth morphology. This present study aims to detect 3D positional information of occlusal contacts from 2D-photos via photogrammetry. We propose an image processing solution for analysis of occlusal contacts and facets via the black silicone method and a photogrammetric technique. The occlusal facets were reconstructed from a 2D-photograph data-set of inter-occlusal records into a 3D image via photogrammetry. The configuration of the occlusal surface was reproduced with polygons. In addition, the textures of the occlusal contacts were mapped to each polygon. DIFFERENCE FROM CONVENTIONAL METHODS: Constructing occlusal facets with 3D polygons from 2D-photos with photogrammetry was a defining characteristic of this image processing technique. It allowed us to better observe findings of the black silicone method. Compared with conventional 3D analysis using a 3D scanner, our 3D models did not reproduce the detail of the anatomical configuration. However, by merging the findings of the inter-occlusal record, the deformation of mandible and the displacement of periodontal ligaments under occlusal force were reflected in our model. EFFECT OR PERFORMANCE: Through the use of polygons in the conversion of 2D images to 3D images, we were able to define the relation between the location and direction of the occlusal contacts and facets, which was difficult to detect via conventional methods. Through our method of making a 3D polygon model, the findings of inter-occlusal records which reflected the jaw/teeth behavior under occlusal force could be observed 3-dimensionally. Copyright © 2012 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  5. Aberrant mural cell recruitment to lymphatic vessels and impaired lymphatic drainage in a murine model of pulmonary fibrosis.

    Science.gov (United States)

    Meinecke, Anna-Katharina; Nagy, Nadine; Lago, Gabriela D'Amico; Kirmse, Santina; Klose, Ralph; Schrödter, Katrin; Zimmermann, Annika; Helfrich, Iris; Rundqvist, Helene; Theegarten, Dirk; Anhenn, Olaf; Orian-Rousseau, Véronique; Johnson, Randall S; Alitalo, Kari; Fischer, Jens W; Fandrey, Joachim; Stockmann, Christian

    2012-06-14

    Pulmonary fibrosis is a progressive disease with unknown etiology that is characterized by extensive remodeling of the lung parenchyma, ultimately resulting in respiratory failure. Lymphatic vessels have been implicated with the development of pulmonary fibrosis, but the role of the lymphatic vasculature in the pathogenesis of pulmonary fibrosis remains enigmatic. Here we show in a murine model of pulmonary fibrosis that lymphatic vessels exhibit ectopic mural coverage and that this occurs early during the disease. The abnormal lymphatic vascular patterning in fibrotic lungs was driven by expression of platelet-derived growth factor B (PDGF-B) in lymphatic endothelial cells and signaling through platelet-derived growth factor receptor (PDGFR)-β in associated mural cells. Because of impaired lymphatic drainage, aberrant mural cell coverage fostered the accumulation of fibrogenic molecules and the attraction of fibroblasts to the perilymphatic space. Pharmacologic inhibition of the PDGF-B/PDGFR-β signaling axis disrupted the association of mural cells and lymphatic vessels, improved lymphatic drainage of the lung, and prevented the attraction of fibroblasts to the perilymphatic space. Our results implicate aberrant mural cell recruitment to lymphatic vessels in the pathogenesis of pulmonary fibrosis and that the drainage capacity of pulmonary lymphatics is a critical mediator of fibroproliferative changes.

  6. Development of a Numerical Model of Hypervelocity Impact into a Pressurized Composite Overwrapped Pressure Vessel

    Science.gov (United States)

    Garcia, M. A.; Davis, B. A.; Miller, J. E.

    2017-01-01

    . Also seen in the figure is the eroded projectile that had passed into the COPV vessel with the generated shock wave in the pressurant propagating just ahead of the material. In this paper, pertinent experimental details and the development of the material constitutive models necessary for this work along with the efforts to validate their use are dis-cussed. The simulation results are presented and compared with the NASA experimental observations. While work is on-going from this effort, early observations pertinent to the failure threshold are presented.

  7. Celiac artery stenosis/occlusion treated by interventional radiology

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Osamu [Department of Diagnostic Radiology, Kumamoto University Graduate School of Medical and Pharmaceutical Sciences, 1-1-1, Honjo Kumamoto 860-8505 (Japan)], E-mail: osamu-3643ik@do9.enjoy.ne.jp; Tamura, Yoshitaka; Nakasone, Yutaka; Yamashita, Yasuyuki [Department of Diagnostic Radiology, Kumamoto University Graduate School of Medical and Pharmaceutical Sciences, 1-1-1, Honjo Kumamoto 860-8505 (Japan)

    2009-08-15

    Severe stenosis/occlusion of the proximal celiac trunk due to median arcuate ligament compression (MALC), arteriosclerosis, pancreatitis, tumor invasion, and celiac axis agenesis has been reported. However, clinically significant ischemic bowel disease attributable to celiac axis stenosis/occlusion appears to be rare because the superior mesenteric artery (SMA) provides for rich collateral circulation. In patients with celiac axis stenosis/occlusion, the most important and frequently encountered collateral vessels from the SMA are the pancreaticoduodenal arcades. Patients with celiac artery stenosis/occlusion are treated by interventional radiology (IR) via dilation of the pancreaticoduodenal arcade. In patients with dilation of the pancreaticoduodenal arcade on SMA angiograms, IR through this artery may be successful. Here we provide several tips on surmounting these difficulties in IR including transcatheter arterial chemoembolization for hepatocellular carcinoma, an implantable port system for hepatic arterial infusion chemotherapy to treat metastatic liver tumors, coil embolization of pancreaticoduodenal artery aneurysms, and arterial stimulation test with venous sampling for insulinomas.

  8. Local intra-arterial fibrinolysis without arterial occlusion?

    Energy Technology Data Exchange (ETDEWEB)

    Schumacher, M.; Yin, L.; Klisch, J. [Section Neuroradiology, Univ. Hospital, Freiburg (Germany); Hetzel, A. [Dept. of Neurology, Univ. Hospital, Freiburg (Germany)

    1999-07-01

    Local intra-arterial fibrinolysis (LIF) is the best choice at present for treatment of acute vessel occlusion in the vertebrobasilar teritory and also, in selected cases, in the carotid territory. In almost all cases angiography demonstrates the site of occlusion exactly and gives information about collateral circulation. Contrary to this common approach, we report five patients with severe acute thromboembolic stroke in whom angiography revealed no occlusion of relevant arteries or their main branches. Under the hypothesis of persisting occlusion of perforating arteries to the brain stem we performed LIF in patients with a clinical basilar artery syndrome. Outcome in all but one of them was good following LIF. The clinical details are described and possible reasons discussed. (orig.)

  9. New angiographic measurement tool for analysis of small cerebral vessels: application to a subarachnoid haemorrhage model in the rat

    Energy Technology Data Exchange (ETDEWEB)

    Turowski, B.; Moedder, U. [Heinrich-Heine University, Institute of Diagnostic Radiology, Neuroradiology, Duesselorf (Germany); Haenggi, D.; Steiger, H.J. [Heinrich-Heine University, Department of Neurosurgery, Duesseldorf (Germany); Beck, A.; Aurich, V. [Heinrich-Heine University, Institute of Informatics, Duesseldorf (Germany)

    2007-02-15

    Exact quantification of vasospasm by angiography is known to be difficult especially in small vessels. The purpose of the study was to develop a new method for computerized analysis of small arteries and to demonstrate feasibility on cerebral angiographies of rats acquired on a clinical angiography unit. A new software tool analysing grey values and subtracting background noise was validated on a vessel model. It was tested in practice in animals with subarachnoid haemorrhage (SAH). A total of 28 rats were divided into four groups: SAH untreated, SAH treated with local calcium antagonist, SAH treated with placebo, and sham-operated. The diameters of segments of the internal carotid, caudal cerebral, middle cerebral, rostral cerebral and the stapedial arteries were measured and compared to direct measurements of the diameters on magnified images. There was a direct correlation between the cross-sectional area of vessels measured in a phantom and the measurements acquired using the new image analysis method. The spread of repeated measurements with the new software was small compared to the spread of direct measurements of vessel diameters on magnified images. Application of the measurement tool to experimental SAH in rats showed a statistically significant reduction of vasospasm in the SAH groups treated with nimodipine-releasing pellets in comparison to all the other groups combined. The presented computerized method for analysis of small intracranial vessels is a new method allowing precise relative measurements. Nimodipine-releasing subarachnoidal pellets reduce vasospasm, but further testing with larger numbers is necessary. The tool can be applied to human angiography without modification and offers the promise of substantial progress in the diagnosis of vasospasm after SAH. (orig.)

  10. A Constraint Programming Model for Fast Optimal Stowage of Container Vessel Bays

    DEFF Research Database (Denmark)

    Delgado-Ortegon, Alberto; Jensen, Rune Møller; Janstrup, Kira

    Container vessel stowage is a combinatorial optimization problem with both high economic and environmental impact. The most successful approaches to tackle this problem use hierarchical decompositions in which the sub-problems of these decompositions assign containers to slots in individual vesse...

  11. Maury Journals - US Vessels

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — U.S. vessels observations, after the 1853 Brussels Conference that set International Maritime Standards, modeled after Maury Marine Standard Observations.

  12. Differential Diagnosis of Chronic Total Occlusive and Subtotal Occlusive Disease of the Lower Extremity Arteries Using Reverse Attenuation Gradient Sign on CT Angiography.

    Science.gov (United States)

    Lee, Jung Eun; Park, Hee Jin; Lee, So Yeon; Chung, Eun Chul; Rho, Myung Ho; Cha, Jang Gyu; Lee, Sun Joo

    2015-11-01

    The purpose of this study is to evaluate the diagnostic usefulness of the reverse attenuation gradient sign in occlusive lower extremity arterial disease through CT angiography (CTA). This study sample enrolled 45 men and eight women in the chronic total occlusion group and 30 men and seven women in the subtotal occlusion group. Luminal CT attenuation (in Hounsfield units) was measured at three points from the end of the occlusion site to the first collateral vessel's insertion point. We also used Hounsfield units to measure the CT attenuation of the opposite side artery at the same level in a similar manner. We compared each value using the Mann-Whitney U test. The absolute value of the mean differences in the Hounsfield units among the proximal, middle, and distal portion of chronic total occlusions were higher than those of subtotal occlusions, and this result was statistically significant (p total occlusions were statistically significantly lower than those of subtotal occlusions. The reverse attenuation gradient sign can be applied to the lower extremity arteries and can be helpful for differential diagnosis of chronic total occlusions from subtotal occlusions using CTA.

  13. Development of a dynamic in vitro model of a stented blood vessel to evaluate the effects of stent strut material selection and surface coating on smooth muscle cell response

    Science.gov (United States)

    Winn, Bradley Huegh

    Cardiovascular disease is the leading cause of mortality in The United States and Europe, accounting for approximately half of all deaths. The most common form of cardiovascular disease is atherosclerosis, which is characterized by the formation of fatty atheromatous plaques that can grow to occlude the vessel lumen, thus causing ischemia distal to the occlusion. This is commonly treated using balloon angioplasty, which is usually done in conjunction with the deployment of a stent. Stent deployment helps hold the vessel open following the local injury caused by balloon inflation and prevents elastic recoil and subsequent negative remodeling. Stenting has been shown to significantly reduce restenosis rates from approximately 20-50% without a stent to about 10-30% with stent deployment. However, restenosis still remains the main cause of long-term stent failure. In basic terms, a balloon angioplasty procedure is a forceful displacement of an atherosclerotic lesion serving to widen the vessel lumen to increase blood flow. This procedure causes stretching of the vessel wall, tears in the atherosclerotic plaques, and general damage to the vessel in turn signaling a complex cascade of thrombosis, inflammation, intimal thickening, and vascular remodeling. Stent deployment also further complicates the immunological response by triggering a foreign body response from the implantation of a biomaterial into the body. When performing an angioplasty procedure, particularly in conjunction with stent deployment, a certain degree of vascular injury is inevitable. However, the initial injury can be further complicated by the body's local reaction to the implanted biomaterial, the severity of which can ultimately dictate the degree of restenosis and subsequently affect procedural success. The proliferative response of VSMCs to the various afore mentioned stimuli results in the formation of often copious amounts of neointimal tissue, generally known as intimal hyperplasia. The

  14. Pathogenesis and pathology of HIVrelated large-vessel disease ...

    African Journals Online (AJOL)

    The first reported series of large-vessel aneurysms in patients with HIV infection emanated from Zimbabwe.1,2 A more comprehensive study of the pathology was reported by Nair et al. in 1999.3 More recently there has been some focus on occlusive large-vessel disease, with separate reports by Nair et al.4 and Mulaudzi et ...

  15. Pregnancy after tubal occlusion

    African Journals Online (AJOL)

    1983-04-02

    Apr 2, 1983 ... the procedure and 2 mistakenly thought that they had been sterilized - one at the time of a salpingectomy for ectopic pregnancy and the other at a repeat caesarean section. The pregnancy rate was therefore 24 out of 9430 procedures, or. 2,5/1000. Repeat tubal occlusion has been performed in 10 of the 16.

  16. Follicular occlusion triad

    Directory of Open Access Journals (Sweden)

    Mittal R

    1993-01-01

    Full Text Available One 40-year female was diagnosed as a case of follicular occlusion triad (FOT as she had hidradenitis suppurativa, acne conglobata and perifolliculitis capitis abscedens et suffodiens since 7 years. Partial improvement occurred within 20 days of treatment with co-trimoxazole and haematinics but relapse occurred after 5 days of stopping antibiotics.

  17. Strain gauge analysis of occlusal forces on implant prostheses at various occlusal heights.

    Science.gov (United States)

    Cho, Young-Eun; Park, Eun-Jin; Koak, Jai-Young; Kim, Seong-Kyun; Heo, Seong-Joo; Park, Ji-Man

    2014-01-01

    The purpose of this study was to evaluate and compare the strain development at different occlusal heights of an implant prosthesis and adjacent teeth through the use of strain gauges. A test model was constructed using autopolymerizing polyurethane resin, artificial composite resin teeth, and an implant gold crown in the mandibular first molar area. The resin block containing the implant and the gold crown was sectioned, and two expansion screws were attached perpendicular to the bottom of the resin block on the buccal and lingual sides. The expansion screws were turned to create a gap. Four groups were created based on the occlusal height of the implant gold crown. Three strain gauges were attached to the buccal surfaces of the mandibular right second premolar, implant gold crown, and second molar. Beef jerky, carrot, and bread were used as test foods. A universal testing machine was used to apply compressive forces of 300 N (beef jerky), 250 N (carrot), and 50 N (bread), and the occlusal force was measured in each group. With 300 N, occlusal forces were concentrated on the adjacent teeth when the occlusal height of the implant prosthesis decreased. With 250 and 50 N, when the occlusal height of the implant prosthesis increased, the occlusal force applied to the implant prosthesis increased, but alterations in the implant crown height had little effect on the adjacent teeth. Different amounts of strain in the implant prosthesis and adjacent teeth were recorded depending on the occlusal height of the prosthesis. With 250 or 50 N of force, an increased prosthesis height affected the implant itself. With 300 N of force, decreased occlusal height of the prosthesis resulted in increased force on the adjacent teeth.

  18. Voxel-Space Ambient Occlusion

    Science.gov (United States)

    2012-02-01

    REPORT Voxel-Space Ambient Occlusion 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Ambient occlusion adds important detail to a scene. This paper...presents a multiresolution screen-space voxel based ambient occlusion technique, which improves G-buffer based techniques, avoiding artifacts such as haloing...Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS Voxels, ambient occlusion, interactive visibility Rajeev

  19. Atherosclerosis: contrast-enhanced MR imaging of vessel wall in rabbit model--comparison of gadofosveset and gadopentetate dimeglumine.

    Science.gov (United States)

    Lobbes, Marc B I; Miserus, Robbert-Jan J H M; Heeneman, Sylvia; Passos, Valeria Lima; Mutsaers, Peter H A; Debernardi, Nicola; Misselwitz, Bernd; Post, Mark; Daemen, Mat J A P; van Engelshoven, Jos M A; Leiner, Tim; Kooi, Marianne E

    2009-03-01

    To investigate the potential of gadofosveset for contrast material-enhanced magnetic resonance (MR) imaging of plaque in a rabbit model of atherosclerosis. All experiments were approved by the animal ethics committee. Thirty-one New Zealand White rabbits were included in one of four study groups: animals with atherosclerosis imaged with gadofosveset (n = 10) or gadopentetate dimeglumine (n = 7) and control animals imaged with gadofosveset (n = 7) or gadopentetate dimeglumine (n = 7). Aortic atherosclerosis was induced through endothelial denudation combined with a cholesterol-enriched diet. Control rabbits underwent a sham surgical procedure and received a regular diet. After 8 weeks, pre- and postcontrast T1-weighted MR images of the aortic vessel wall were acquired. Relative signal enhancement was determined with dedicated software. Statistical analysis was performed by using a generalized linear mixed model. Immunohistochemical staining with CD31 and albumin was used to assess microvessel density and the albumin content of the vascular wall. Group differences were analyzed by using a chi(2) test. Gadofosveset spatial distribution and content within the vessel wall were determined with proton-induced x-ray emission (PIXE) analysis. Postcontrast signal enhancement was significantly greater for atherosclerotic than for control animals imaged with gadofosveset (P = .022). Gadopentetate dimeglumine could not enable discrimination between normal and atherosclerotic vessel walls (P = .428). PIXE analysis showed higher amounts of gadopentetate dimeglumine than gadofosveset in both atherosclerotic and normal rabbit aortas. Immunohistochemical staining revealed the presence of albumin and increased microvessel density in the vascular walls of atherosclerotic rabbits. These results suggest that gadofosveset can be used to differentiate between atherosclerotic and normal rabbit vessel walls. http://radiology.rsnajnls.org/cgi/content/full/250/3/682/DC1. RSNA, 2009

  20. Validation of the fast-running in-vessel model ASTRID for predicting the radioactive releases to the containment

    Energy Technology Data Exchange (ETDEWEB)

    Jaakko, M. [VTT Processes (Finland); Schmuck, P. [Forschungszentrum Karlsruhe, Karlsruhe (Germany)

    2004-07-01

    The ASTRID (Assessment of Source Term for Emergency Response based on Installation Data) process model is used for the faster than real-time prediction of the radioactivity released into the containment and further into the environment in case of an emergency situation in a light water reactor. Combined together with the containment module COCOSYS the model can predict the entire radioactivity release chain from the primary system to the containment and further into the environment. In the paper the ASTRID thermohydraulic module PROCESS is presented shortly. The thermohydraulic part is a fast running solution for the drift-flux based thermohydraulics. In high temperatures the core degradation leading to the melt pool formation in the reactor barrel and reactor vessel lower head is calculated in the in-vessel module RELOMEL. Finally after the reactor vessel wall has been eroded due to the molten corium in the lower plenum, the massive radioactivity release occurs into the containment. But even before this scenario the radioactivity may be transported from the superheated core to the containment by the coolant. The reference plants for the development have been the Westinghouse type 4-loop PWR, the French type 3-loop PWR, The German type 4-loop Konvoi PWR, the Loviisa VVER type PWR, and the Olkiluoto type internal pump BWR. The reference code for the DBA thermal hydraulics has been the SMABRE code. In the developmental assessment the capability of the rough nodalization of ASTRID has been tested against the SMABRE nodalization describing the plants with 50 - 500 nodes. For the developmental assessment of the in-vessel severe accident the sample cases are calculated with MELCOR. The more thorough validation is based on the internationally known system codes, RELAP5, MELCOR, CATHARE and ATHLET. In the validation the most problematic area is the radioactivity transport into the containment. This part of the validation is done with the integrated code system. (authors)

  1. Excessive Reversal of Epidermal Growth Factor Receptor and Ephrin Signaling Following Tracheal Occlusion in Rabbit Model of Congenital Diaphragmatic Hernia.

    Science.gov (United States)

    Varisco, Brian M; Sbragia, Lourenco; Chen, Jing; Scorletti, Federico; Joshi, Rashika; Wong, Hector R; Lopes-Figueira, Rebecca; Oria, Marc; Peiro, Jose

    2016-07-19

    Congenital diaphragmatic hernia (CDH) causes severe pulmonary hypoplasia from herniation of abdominal contents into the thorax. Tracheal occlusion (TO) for human CDH improves survival, but morbidity and mortality remain high, and we do not fully understand the cellular pathways and processes most severely impacted by CDH and TO. We created a left diaphragmatic hernia (DH) in rabbit fetuses with subsequent TO and collected left lung sections for NextGen mRNA sequencing. DH, TO, and DHTO fetuses had comparable body and organ growth to control except for lower lung weights in DH (p<0.05). Of 13,687 expressed genes, DHTO had 687 differentially expressed genes compared to DH, but no other group-group comparison had more than 10. Considering genes in combination, many of the genes reduced in DH were more highly expressed in DHTO than in control. Benchmarking fetal rabbit lung gene expression to published lung development data, both DH and DHTO lungs were more highly correlated with the gene expression of immature lung. DNA synthesis was upregulated in DHTO compared to DH and ribosome and protein synthesis pathways were downregulated. DH reduced total and epithelial cell proliferation by half and two-thirds respectively, and DHTO increased proliferation by 2.5 and 3.4-fold respectively. Signaling pathways downregulated by DH and upregulated in DHTO were epidermal growth factor receptor signaling, ephrin signaling, and cell migration; however, levels of ephrin and EGFR signaling in DHTO exceeded that of control. Identification and inhibition of the ligands responsible for this dysregulated signaling could improve lung development in CDH.

  2. Research vessels

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, P.S.

    by the research vessels RV Gaveshani and ORV Sagar Kanya are reported. The work carried out by the three charted ships is also recorded. A short note on cruise plans for the study of ferromanganese nodules is added...

  3. Outcome and Treatment Effects in Stroke Associated with Acute Cervical ICA Occlusion.

    Science.gov (United States)

    Gliem, Michael; Lee, John-Ih; Barckhan, Aurica; Turowski, Bernd; Hartung, Hans-Peter; Jander, Sebastian

    2017-01-01

    Endovascular therapy (EVT) with stent retrievers in addition to i.v. thrombolysis (IVT) has proven effective in acute stroke patients with middle cerebral artery (MCA, M1 segment) and distal internal carotid artery (ICA) occlusion. Limited data exist concerning acute cervical ICA occlusion, either alone or in combination with intracranial ICA occlusion (tandem occlusion). Therefore we analyzed outcome and treatment effects in stroke associated with cervical ICA occlusion, with specific focus on the impact of intracranial ICA or M1 patency. Seventy-eight patients with cervical ICA occlusion from our local stroke unit registry were analyzed retrospectively. Thrombolysis in Cerebral Infarction (TICI) classification, infarct size, modified Rankin scale (mRS), symptomatic intracerebral hemorrhage (ICH), and death were assessed as outcome parameters. Forty-three patients had isolated cervical ICA occlusion whereas 35 patients presented with extra-/intracranial tandem occlusion. Patients underwent IVT alone (n = 23), combined IVT/EVT (n = 28) or no treatment (n = 27). Treated and untreated patients with tandem occlusion had a worse outcome after 90 days compared to isolated cervical occlusion (OR for moderate outcome 0.29, 0.27-0.88, p = 0.01). Additional EVT improved outcome in patients with tandem occlusion (OR for moderate outcome: 15.43, 1.60-148.90, p = 0.008) but not isolated cervical occlusion (OR 1.33, 0.38-11.60, NS). In contrast to tandem occlusion, stroke outcome in patients with isolated cervical ICA occlusion was generally more benign and not improved by combined IVT/EVT compared to IVT alone. Intracranial vessel patency may be critical for treatment decision in acute cervical ICA occlusion.

  4. Model of passage of vessels through the waterway section forming the schedule in the course of its implementation

    Directory of Open Access Journals (Sweden)

    S. N. Plotnikov

    2017-01-01

    Full Text Available The model of passage of vessels through a section of the waterway is considered, which independently determines the order of passage of vessels with limited capacity of sections of the track. Such a model will consist of a number of standard algorithmic networks. When composing the schedule in the model, the following preference rules were used: first-come-first-served (that is, if the ship occupied the workplace, this decision is not canceled; The rule of the shortest operation; For the swamps the priority of vessels going downstream (the direction of flow from the source to the drain. An algorithmic network that implements the search for an acceptable schedule must implement the following for conflicting operations: the operation that has started is not interrupted; If several operations simultaneously claim for one workplace (port, reach and their number is greater than its throughput, then the conflict resolution is carried out in accordance with predefined preference rules or based on the user's decision; If the operation is waiting for the release of the workplace, it does not occupy the resource; The resource is returned immediately after the operation is completed. The considered design of algorithmic networks allows to resolve the conflict, with a simultaneous resource request, to take the resource once, remember that it was received and return it after the end of the operation, then the resource receives a contra-controlling operation for execution. However, the use of this design introduces redundancy into the model, even if it is used only for conflicting operations. The model is presented in the language of algorithmic networks and is implemented in the system of modeling automation KOGNITRON.

  5. Shear-sensitive nanocapsule drug release for site-specific inhibition of occlusive thrombus formation

    NARCIS (Netherlands)

    Molloy, C. P.; Yao, Y.; Kammoun, H.; Bonnard, T.; Hoefer, T.; Alt, K.; Tovar-Lopez, F.; Rosengarten, G.; Ramsland, P. A.; van der Meer, A. D.; van den Berg, A.; Murphy, A. J.; Hagemeyer, C. E.; Peter, K.; Westein, E.

    2017-01-01

    Essentials Vessel stenosis due to large thrombus formation increases local shear 1-2 orders of magnitude. High shear at stenotic sites was exploited to trigger eptifibatide release from nanocapsules. Local delivery of eptifibatide prevented vessel occlusion without increased tail bleeding times.

  6. Growth Description for Vessel Wall Adaptation: A Thick-Walled Mixture Model of Abdominal Aortic Aneurysm Evolution.

    Science.gov (United States)

    Grytsan, Andrii; Eriksson, Thomas S E; Watton, Paul N; Gasser, T Christian

    2017-08-25

    (1) Background: Vascular tissue seems to adapt towards stable homeostatic mechanical conditions, however, failure of reaching homeostasis may result in pathologies. Current vascular tissue adaptation models use many ad hoc assumptions, the implications of which are far from being fully understood; (2) Methods: The present study investigates the plausibility of different growth kinematics in modeling Abdominal Aortic Aneurysm (AAA) evolution in time. A structurally motivated constitutive description for the vessel wall is coupled to multi-constituent tissue growth descriptions; Constituent deposition preserved either the constituent's density or its volume, and Isotropic Volume Growth (IVG), in-Plane Volume Growth (PVG), in-Thickness Volume Growth (TVG) and No Volume Growth (NVG) describe the kinematics of the growing vessel wall. The sensitivity of key modeling parameters is explored, and predictions are assessed for their plausibility; (3) Results: AAA development based on TVG and NVG kinematics provided not only quantitatively, but also qualitatively different results compared to IVG and PVG kinematics. Specifically, for IVG and PVG kinematics, increasing collagen mass production accelerated AAA expansion which seems counterintuitive. In addition, TVG and NVG kinematics showed less sensitivity to the initial constituent volume fractions, than predictions based on IVG and PVG; (4) Conclusions: The choice of tissue growth kinematics is of crucial importance when modeling AAA growth. Much more interdisciplinary experimental work is required to develop and validate vascular tissue adaption models, before such models can be of any practical use.

  7. Assessing advantages of sequential boron neutron capture therapy (BNCT) in an oral cancer model with normalized blood vessels.

    Science.gov (United States)

    Molinari, Ana J; Thorp, Silvia I; Portu, Agustina M; Saint Martin, Gisela; Pozzi, Emiliano C C; Heber, Elisa M; Bortolussi, Silva; Itoiz, Maria E; Aromando, Romina F; Monti Hughes, Andrea; Garabalino, Marcela A; Altieri, Saverio; Trivillin, Verónica A; Schwint, Amanda E

    2015-01-01

    We previously demonstrated the therapeutic success of sequential boron neutron capture therapy (Seq-BNCT) in the hamster cheek pouch oral cancer model. It consists of BPA-BNCT followed by GB-10-BNCT 24 or 48 hours later. Additionally, we proved that tumor blood vessel normalization with thalidomide prior to BPA-BNCT improves tumor control. The aim of the present study was to evaluate the therapeutic efficacy and explore potential boron microdistribution changes in Seq-BNCT preceded by tumor blood vessel normalization. Tumor bearing animals were treated with thalidomide for tumor blood vessel normalization, followed by Seq-BNCT (Th+ Seq-BNCT) or Seq-Beam Only (Th+ Seq-BO) in the window of normalization. Boron microdistribution was assessed by neutron autoradiography. Th+ Seq-BNCT induced overall tumor response of 100%, with 87 (4)% complete tumor response. No cases of severe mucositis in dose-limiting precancerous tissue were observed. Differences in boron homogeneity between tumors pre-treated and not pre-treated with thalidomide were observed. Th+ Seq-BNCT achieved, for the first time, response in all treated tumors. Increased homogeneity in tumor boron microdistribution is associated to an improvement in tumor control.

  8. Automated Vessel Segmentation Using Infinite Perimeter Active Contour Model with Hybrid Region Information with Application to Retinal Images.

    Science.gov (United States)

    Zhao, Yitian; Rada, Lavdie; Chen, Ke; Harding, Simon P; Zheng, Yalin

    2015-09-01

    Automated detection of blood vessel structures is becoming of crucial interest for better management of vascular disease. In this paper, we propose a new infinite active contour model that uses hybrid region information of the image to approach this problem. More specifically, an infinite perimeter regularizer, provided by using L(2) Lebesgue measure of the γ -neighborhood of boundaries, allows for better detection of small oscillatory (branching) structures than the traditional models based on the length of a feature's boundaries (i.e., H(1) Hausdorff measure). Moreover, for better general segmentation performance, the proposed model takes the advantage of using different types of region information, such as the combination of intensity information and local phase based enhancement map. The local phase based enhancement map is used for its superiority in preserving vessel edges while the given image intensity information will guarantee a correct feature's segmentation. We evaluate the performance of the proposed model by applying it to three public retinal image datasets (two datasets of color fundus photography and one fluorescein angiography dataset). The proposed model outperforms its competitors when compared with other widely used unsupervised and supervised methods. For example, the sensitivity (0.742), specificity (0.982) and accuracy (0.954) achieved on the DRIVE dataset are very close to those of the second observer's annotations.

  9. Implementation of a practical model for light and heat distribution using laser-induced thermotherapy near to a large vessel

    Energy Technology Data Exchange (ETDEWEB)

    Verhey, J F [Department of Medical Informatics, University of Goettingen, Robert-Koch-Str. 40, D-37075 Goettingen (Germany); Mohammed, Y [Department of Medical Informatics, University of Goettingen, Robert-Koch-Str. 40, D-37075 Goettingen (Germany); Ludwig, A [Department of Craneo-Maxillofacial Surgery, University of Goettingen, Robert-Koch-Str. 40, D-37075 Goettingen (Germany); Giese, K [Department of Medical Informatics, University of Goettingen, Robert-Koch-Str. 40, D-37075 Goettingen (Germany)

    2003-11-07

    This paper introduces a simulation model for light and heat transport in tissues including perfusion effects. The model enables an efficient simulation of the damaged zone induced with an optical fibre for laser interstitial thermotherapy (LITT). It is designed specially for, but not limited to, tissue ablation in the neck region near to vessels. We describe in detail the effects of the rise in temperature caused by the absorption of light in tissue, using the heat equation and including the cooling effects of flow in vessels and of microperfusion in tissue in order to determine the extent of thermal damage. The extent of the necrosis zone is calculated with a damage function at each point of a finite element method (FEM) mesh. The FEM mesh is implemented with FEMLAB 2.3 as an add-on for finite element modelling for Matlab 6.5. LITT for tumour ablation in liver and some other anatomical regions is a well-known and established method (Bundesaerztekammer und Kassenaerztliche Bundesvereinigung 2002 Assessment der Bundesaerztekammer und der Kassenaerztlichen Bundesvereinigung, Koeln). Investigations of treatments using LITT in the neck region are still in progress. We propose a refined model to validate the LITT method in the future in another anatomic region, e.g., in the highly sensitive region of the neck. Our calculations show that in order to induce a lesion with a maximum diameter of about 1 cm near to a large vessel, an application time between 3 and 4 min is needed using a laser power of about 10 W with a Nd:YAG 1064 nm radiation wavelength.

  10. Implementation of a practical model for light and heat distribution using laser-induced thermotherapy near to a large vessel

    Science.gov (United States)

    Verhey, J. F.; Mohammed, Y.; Ludwig, A.; Giese, K.

    2003-11-01

    This paper introduces a simulation model for light and heat transport in tissues including perfusion effects. The model enables an efficient simulation of the damaged zone induced with an optical fibre for laser interstitial thermotherapy (LITT). It is designed specially for, but not limited to, tissue ablation in the neck region near to vessels. We describe in detail the effects of the rise in temperature caused by the absorption of light in tissue, using the heat equation and including the cooling effects of flow in vessels and of microperfusion in tissue in order to determine the extent of thermal damage. The extent of the necrosis zone is calculated with a damage function at each point of a finite element method (FEM) mesh. The FEM mesh is implemented with FEMLAB 2.3 as an add-on for finite element modelling for Matlab 6.5. LITT for tumour ablation in liver and some other anatomical regions is a well-known and established method (Bundesärztekammer und Kassenärztliche Bundesvereinigung 2002 Assessment der Bundesärztekammer und der Kassenärztlichen Bundesvereinigung, Köln). Investigations of treatments using LITT in the neck region are still in progress. We propose a refined model to validate the LITT method in the future in another anatomic region, e.g., in the highly sensitive region of the neck. Our calculations show that in order to induce a lesion with a maximum diameter of about 1 cm near to a large vessel, an application time between 3 and 4 min is needed using a laser power of about 10 W with a Nd:YAG 1064 nm radiation wavelength.

  11. Modeling corium jet breakup in water pool and application to ex-vessel fuel–coolant interaction analyses

    Energy Technology Data Exchange (ETDEWEB)

    Bang, Kwang-Hyun, E-mail: khbang@hhu.ac.kr; Kumar, Rohit; Kim, Hyoung-Tak

    2014-09-15

    Highlights: • Kelvin–Helmholtz Instability on melt–steam–water interfaces was solved numerically. • Corium jet breakup model was developed for FCI codes based on the KHI solutions. • Ex-vessel steam explosions in reactor cavity were calculated using TRACER-II code. - Abstract: In light water reactor core melt accidents, the molten fuel can be brought into contact with coolant water in the course of the melt relocation in-vessel and ex-vessel as well as in an accident mitigation action of water addition. For the last several decades, the potential risk of energetic molten fuel coolant interactions (FCIs, steam explosions) has drawn substantial attention in the safety analysis of reactor severe accidents. In this paper, an improved melt jet breakup model is presented and analyses of an energetic fuel–coolant interaction in a PWR cavity (1) partially filled (4 m deep) and (2) completely filled (7 m deep) with water are presented. The TRACER-II code was used in the analyses. For jet breakup model, the full dispersion equation of Kelvin–Helmholtz instability for the melt jet–vapor film–water was solved numerically and the solutions were correlated for use in the TRACER-II code. The new jet breakup model was benchmarked using FARO L28 test data. In reactor calculations the mixing calculations showed that the average melt drop size was much smaller in 4 m deep pool with 3 m free-fall than in 7 m deep pool. The explosion calculations showed that the peak pressure at the center of mixture was ∼90 MPa in 4 m deep pool, ∼25 MPa in 7 m deep pool. It also showed that the maximum impulse at the cavity wall was found at the lower wall in both cases and it was 50 kPa s in 4 m deep pool and 150 kPa s in 7 m deep pool.

  12. Primary stenting as emergency therapy in acute basilar artery occlusion

    Energy Technology Data Exchange (ETDEWEB)

    Spreer, Joachim; Arnold, Sebastian; Klisch, Joachim; Schumacher, Martin [Section of Neuroradiology, University Hospital Freiburg, Breisacher Strasse 64, 79106 Freiburg (Germany); Els, Thomas; Hetzel, Andreas; Huppertz, Hans-Juergen; Oehm, Eckhardt [Department of Neurology, University Hospital Freiburg, Freiburg (Germany)

    2002-09-01

    In three patients with acute occlusion of the basilar artery intra-arterial fibrinolysis resulted in only partial recanalization and revealed severe stenosis as the underlying cause. Application of micro-stents without previous dilatation resulted in vessel re-opening. Two patients had an excellent clinical outcome. One patient died 10 days after the stroke due to brainstem infarction. Emergency primary stent application may improve the outcome in acute basilar artery occlusion, if intra-arterial thrombolysis fails to re-establish a sufficient flow. (orig.)

  13. Occlusion of Internal Carotid Artery in Kimura's Disease

    Directory of Open Access Journals (Sweden)

    Tomonori Tamaki

    2010-01-01

    Full Text Available We describe a unique case of Kimura's disease in which cerebral infarction was caused by occlusion of the right internal carotid artery. A 25-year-old man with Kimura's disease was admitted to our hospital because of left hemiparesis. Computed tomography and magnetic resonance imaging of the head showed infarction in the right frontal and temporal lobes. Cerebral angiography demonstrated right internal carotid artery occlusion affecting the C1 segment, with moyamoya-like collateral vessels arising from the right opthalamic artery. Kimura's disease is a chronic disease characterized by the clinical triad of slowly enlarging subcutaneous masses with lymphoid hyperplasia in the head and neck. It often occurs in young Asian men. In our patient, the pathogenesis of internal carotid artery occlusion was unknown. There have only been a few case reports in which occlusion of the internal carotid artery was associated with autoimmune disease, and no previous cases of internal carotid occlusion associated with Kimura's disease have been reported. We suspected that occlusion of this patient's internal carotid artery may be caused by the autoimmune mechanism that underlies Kimura's disease.

  14. LANL Robotic Vessel Scanning

    Energy Technology Data Exchange (ETDEWEB)

    Webber, Nels W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-25

    Los Alamos National Laboratory in J-1 DARHT Operations Group uses 6ft spherical vessels to contain hazardous materials produced in a hydrodynamic experiment. These contaminated vessels must be analyzed by means of a worker entering the vessel to locate, measure, and document every penetration mark on the vessel. If the worker can be replaced by a highly automated robotic system with a high precision scanner, it will eliminate the risks to the worker and provide management with an accurate 3D model of the vessel presenting the existing damage with the flexibility to manipulate the model for better and more in-depth assessment.The project was successful in meeting the primary goal of installing an automated system which scanned a 6ft vessel with an elapsed time of 45 minutes. This robotic system reduces the total time for the original scope of work by 75 minutes and results in excellent data accumulation and transmission to the 3D model imaging program.

  15. The Vessel Schedule Recovery Problem (VSRP) – A MIP model for handling disruptions in liner shipping

    DEFF Research Database (Denmark)

    Brouer, Berit Dangaard; Dirksen, Jakob; Pisinger, David

    2013-01-01

    Containerized transport by liner shipping companies is a multi billion dollar industry carrying a major part of the world trade between suppliers and customers. The liner shipping industry has come under stress in the last few years due to the economic crisis, increasing fuel costs, and capacity...... or even omitting one. We present the Vessel Schedule Recovery Problem (VSRP) to evaluate a given disruption scenario and to select a recovery action balancing the trade off between increased bunker consumption and the impact on cargo in the remaining network and the customer service level. It is proven...

  16. Development of a surrogate model for analysis of ex-vessel steam explosion in Nordic type BWRs

    Energy Technology Data Exchange (ETDEWEB)

    Grishchenko, Dmitry, E-mail: dmitry@safety.sci.kth.se; Basso, Simone, E-mail: simoneb@kth.se; Kudinov, Pavel, E-mail: pavel@safety.sci.kth.se

    2016-12-15

    Highlights: • Severe accident. • Steam explosion. • Surrogate model. • Sensitivity study. • Artificial neural networks. - Abstract: Severe accident mitigation strategy adopted in Nordic type Boiling Water Reactors (BWRs) employs ex-vessel core melt cooling in a deep pool of water below reactor vessel. Energetic fuel–coolant interaction (steam explosion) can occur during molten core release into water. Dynamic loads can threaten containment integrity increasing the risk of fission products release to the environment. Comprehensive uncertainty analysis is necessary in order to assess the risks. Computational costs of the existing fuel–coolant interaction (FCI) codes is often prohibitive for addressing the uncertainties, including the effect of stochastic triggering time. This paper discusses development of a computationally efficient surrogate model (SM) for prediction of statistical characteristics of steam explosion impulses in Nordic BWRs. The TEXAS-V code was used as the Full Model (FM) for the calculation of explosion impulses. The surrogate model was developed using artificial neural networks (ANNs) and the database of FM solutions. Statistical analysis was employed in order to treat chaotic response of steam explosion impulse to variations in the triggering time. Details of the FM and SM implementation and their verification are discussed in the paper.

  17. Left atrial appendage occlusion

    Directory of Open Access Journals (Sweden)

    Ahmad Mirdamadi

    2013-01-01

    Full Text Available Left atrial appendage (LAA occlusion is a treatment strategy to prevent blood clot formation in atrial appendage. Although, LAA occlusion usually was done by catheter-based techniques, especially percutaneous trans-luminal mitral commissurotomy (PTMC, it can be done during closed and open mitral valve commissurotomy (CMVC, OMVC and mitral valve replacement (MVR too. Nowadays, PTMC is performed as an optimal management of severe mitral stenosis (MS and many patients currently are treated by PTMC instead of previous surgical methods. One of the most important contraindications of PTMC is presence of clot in LAA. So, each patient who suffers of severe MS is evaluated by Trans-Esophageal Echocardiogram to rule out thrombus in LAA before PTMC. At open heart surgery, replacement of the mitral valve was performed for 49-year-old woman. Also, left atrial appendage occlusion was done during surgery. Immediately after surgery, echocardiography demonstrates an echo imitated the presence of a thrombus in left atrial appendage area, although there was not any evidence of thrombus in pre-pump TEE. We can conclude from this case report that when we suspect of thrombus of left atrial, we should obtain exact history of previous surgery of mitral valve to avoid misdiagnosis clotted LAA, instead of obliterated LAA. Consequently, it can prevent additional evaluations and treatments such as oral anticoagulation and exclusion or postponing surgeries including PTMC.

  18. A computational model of microbubble transport through a blood-filled vessel bifurcation

    Science.gov (United States)

    Calderon, Andres

    2005-11-01

    We are developing a novel gas embolotherapy technique to occlude blood vessels and starve tumors using gas bubbles that are produced by the acoustic vaporization of liquid perfluorocarbon droplets. The droplets are small enough to pass through the microcirculation, but the subsequent bubbles are large enough to lodge in vessels. The uniformity of tumor infarction depends on the transport the blood-borne bubbles before they stick. We examine the transport of a semi-infinite bubble through a single bifurcation in a liquid-filled two-dimensional channel. The flow is governed by the conservation of fluid mass and momentum equations. Reynolds numbers in the microcirculation are small, and we solve the governing equations using the boundary element method. The effect of gravity on bubble splitting is investigated and results are compared with our previous bench top experiments and to a quasi-steady one-dimensional analysis. The effects of daughter tube outlet pressures and bifurcation geometry are also considered. The findings suggest that slow moving bubbles will favor the upper branch of the bifurcation, but that increasing the bubble speed leads to more even splitting. It is also found that some bifurcation geometries and flow conditions result in severe thinning of the liquid film separating the bubble from the wall, suggesting the possibility bubble-wall contact. This work is supported by NSF grant BES-0301278 and NIH grant EB003541.

  19. Numeric simulation of occlusal interferences in molars restored with ultrathin occlusal veneers.

    Science.gov (United States)

    Magne, Pascal; Cheung, Raymond

    2017-01-01

    Selecting material for a minimally invasive occlusal veneer reconstruction concept requires an understanding of how stresses are distributed during functional and parafunctional forces. The purpose of this in vitro study was to investigate stress distribution in a maxillary molar restored with ultrathin occlusal veneers and subjected by an antagonistic mandibular molar to clenching and working and nonworking movements. A maxillary first molar was modeled from microcomputed tomography (micro-CT) data, using medical image processing software, stereolithography editing/optimizing software, and finite element software. Simulated ultrathin occlusal veneer materials were used. The mandibular molar antagonist was a solid nondeformable geometric entity. Loads simulated clenching, working, and nonworking movements with loading of 500 N. The values of the maximum principal stress were recorded. In the clenching load situation, maximum tensile stresses were located at the occlusal veneer (52 MPa for composite resin versus 47 MPa for ceramic). In the working movement, significant additional tensile stresses were found on the palatal root (87 MPa for composite resin and 85 MPa for ceramic). In the nonworking movement, tensile stress on the ultrathin occlusal veneer increased to 118 MPa for composite resin and 143 MPa for ceramic veneers. Tensile stress peaks shifted to the mesiobuccal root (75 MPa for composite resin and 74 MPa for ceramic). The topography of stresses generated by the various occlusal interferences were clearly identified. Significant tensile stress concentrations were found within the restoration's occlusal topography and root, with the nonworking interference being the most harmful and also the most revealing of the difference between the composite resin and ceramic ultrathin occlusal veneers. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  20. Selective photothermolysis of blood vessels following flashlamp-pumped pulsed dye laser irradiation: in vivo results and mathematical modelling are in agreement.

    Science.gov (United States)

    Babilas, Philipp; Shafirstein, Gal; Bäumler, Wolfgang; Baier, Jürgen; Landthaler, Michael; Szeimies, Rolf-Markus; Abels, Christoph

    2005-08-01

    Laser therapy using the pulsed dye laser is the standard treatment for port-wine stains (PWS). But the mechanism of action has not been elucidated completely, yet. The dorsal skin-fold chamber model in hamsters was used to investigate the effects of laser treatment (lambda(em)=585 nm; pulse duration: 0.45 ms; fluence: 6 J per cm2) on blood vessels. Vessels (n=3394) were marked with FITC dextran (MW 150 kDa) and diameters (2-186 microm) were measured using intravital fluorescence microscopy up to 24 h following irradiation. Histology (H&E, TUNEL, CD31) was taken 1 or 24 h after irradiation. The experimental results were compared with the predictions of a mathematical model based on the finite-element method. Following irradiation treatment the number of unperfused vessels decreases with decreasing vessel diameter in vivo. Histology indicated a restriction of tissue injury to the irradiated area after 1 h. Blood vessels contained aggregated red blood cells. After 24 h tissue damage occurred also outside the irradiated area and thrombus formation was visible. These results were in agreement with the mathematical calculations. In addition to initial physical effects after pulsed dye laser treatment delayed biological processes contribute significantly to the reduction of perfused blood vessels. Because of incomplete photocoagulation of smaller blood vessels (diameter 2-16 microm) a complete bleaching of PWS seems to be unlikely.

  1. Assessment of Blood-Brain Barrier Permeability by Dynamic Contrast-Enhanced MRI in Transient Middle Cerebral Artery Occlusion Model after Localized Brain Cooling in Rats

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Soo [Department of Radiology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068 (Korea, Republic of); Lee, Seung-Koo [Department of Radiology, Yonsei University College of Medicine, Seoul 03722 (Korea, Republic of); Kwon, Mi Jung [Department of Pathology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068 (Korea, Republic of); Lee, Phil Hye [Department of Neurology, Yonsei University College of Medicine, Seoul 03722 (Korea, Republic of); Ju, Young-Su [Department of Industrial Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068 (Korea, Republic of); Yoon, Dae Young [Department of Radiology, Hallym University Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul 05355 (Korea, Republic of); Kim, Hye Jeong [Department of Radiology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul 07441 (Korea, Republic of); Lee, Kwan Seop [Department of Radiology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068 (Korea, Republic of)

    2016-11-01

    The purpose of this study was to evaluate the effects of localized brain cooling on blood-brain barrier (BBB) permeability following transient middle cerebral artery occlusion (tMCAO) in rats, by using dynamic contrast-enhanced (DCE)-MRI. Thirty rats were divided into 3 groups of 10 rats each: control group, localized cold-saline (20℃) infusion group, and localized warm-saline (37℃) infusion group. The left middle cerebral artery (MCA) was occluded for 1 hour in anesthetized rats, followed by 3 hours of reperfusion. In the localized saline infusion group, 6 mL of cold or warm saline was infused through the hollow filament for 10 minutes after MCA occlusion. DCE-MRI investigations were performed after 3 hours and 24 hours of reperfusion. Pharmacokinetic parameters of the extended Tofts-Kety model were calculated for each DCE-MRI. In addition, rotarod testing was performed before tMCAO, and on days 1-9 after tMCAO. Myeloperoxidase (MPO) immunohisto-chemistry was performed to identify infiltrating neutrophils associated with the inflammatory response in the rat brain. Permeability parameters showed no statistical significance between cold and warm saline infusion groups after 3-hour reperfusion 0.09 ± 0.01 min{sup -1} vs. 0.07 ± 0.02 min{sup -1}, p = 0.661 for K{sup trans}; 0.30 ± 0.05 min{sup -1} vs. 0.37 ± 0.11 min{sup -1}, p = 0.394 for kep, respectively. Behavioral testing revealed no significant difference among the three groups. However, the percentage of MPO-positive cells in the cold-saline group was significantly lower than those in the control and warm-saline groups (p < 0.05). Localized brain cooling (20℃) does not confer a benefit to inhibit the increase in BBB permeability that follows transient cerebral ischemia and reperfusion in an animal model, as compared with localized warm-saline (37℃) infusion group.

  2. Assessment of blood-brain barrier permeability by dynamic contrast-enhanced MRI in transient middle cerebral artery occlusion model after localized brain cooling in rats

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Soo; Lee, Kwan Seop; Kwon, Mi Jung; Ju, Young Su [Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang (Korea, Republic of); Lee, Seung Koo; Lee, Phil Hye [Yonsei University College of Medicine, Seoul (Korea, Republic of); Yoon, Dae Young [Dept. of Radiology, Hallym University Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul (Korea, Republic of); Kim, Hye Jeong [Dept. of Radiology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul (Korea, Republic of)

    2016-09-15

    The purpose of this study was to evaluate the effects of localized brain cooling on blood-brain barrier (BBB) permeability following transient middle cerebral artery occlusion (tMCAO) in rats, by using dynamic contrast-enhanced (DCE)-MRI. Thirty rats were divided into 3 groups of 10 rats each: control group, localized cold-saline (20 .deg. ) infusion group, and localized warm-saline (37 .deg. ) infusion group. The left middle cerebral artery (MCA) was occluded for 1 hour in anesthetized rats, followed by 3 hours of reperfusion. In the localized saline infusion group, 6 mL of cold or warm saline was infused through the hollow filament for 10 minutes after MCA occlusion. DCE-MRI investigations were performed after 3 hours and 24 hours of reperfusion. Pharmacokinetic parameters of the extended Tofts-Kety model were calculated for each DCE-MRI. In addition, rotarod testing was performed before tMCAO, and on days 1-9 after tMCAO. Myeloperoxidase (MPO) immunohisto-chemistry was performed to identify infiltrating neutrophils associated with the inflammatory response in the rat brain. Permeability parameters showed no statistical significance between cold and warm saline infusion groups after 3-hour reperfusion 0.09 ± 0.01 min{sup -1} vs. 0.07 ± 0.02 min{sup -1},p = 0.661 for K{sup trans}; 0.30 ± 0.05 min{sup -1} vs. 0.37 ± 0.11 min{sup -1},p = 0.394 for kep, respectively. Behavioral testing revealed no significant difference among the three groups. However, the percentage of MPO-positive cells in the cold-saline group was significantly lower than those in the control and warm-saline groups (p < 0.05). Localized brain cooling (20 .deg. ) does not confer a benefit to inhibit the increase in BBB permeability that follows transient cerebral ischemia and reperfusion in an animal model, as compared with localized warm-saline (37 .deg. ) infusion group.

  3. Therapeutic effect of BDNF-overexpressing human neural stem cells (HB1.F3.BDNF) in a rodent model of middle cerebral artery occlusion.

    Science.gov (United States)

    Chang, Da-Jeong; Lee, Nayeon; Choi, Chunggab; Jeon, Iksoo; Oh, Seung-Hun; Shin, Dong Ah; Hwang, Tae-Sun; Lee, Hong J; Kim, Seung U; Moon, Hyeyoung; Hong, Kwan Soo; Kang, Kyung-Sun; Song, Jihwan

    2013-01-01

    Ischemic stroke mainly caused by middle cerebral artery occlusion (MCAo) represents the major type of stroke; however, there are still very limited therapeutic options for the stroke-damaged patients. In this study, we evaluated the neurogenic and therapeutic potentials of human neural stem cells (NSCs) overexpressing brain-derived neurotrophic factor (HB1.F3.BDNF) following transplantation into a rodent model of MCAo. F3.BDNF human NSCs (F3.BDNF) were transplanted into the contralateral side of striatum at 7 days after MCAo, and the transplanted animals were monitored up to 8 weeks using animal MRI and various behavioral tests before they were sacrificed for immunohistochemical analysis. Interestingly, animal MRI results indicate that the majority of contralaterally transplanted neural stem cells were migrated to the peri-infarct area, showing a pathotropism. Transplanted animals exhibited significant behavioral improvements in stepping, rotarod, and modified neurological severity score (mNSS) tests. We also found that the transplanted human cells were colocalized with nestin, DCX, MAP2, DARPP-32, TH, GAD65/67-positive cells, of which results can be correlated with neural regeneration and behavioral recovery in the transplanted animals. More importantly, we were able to detect high levels of human BDNF protein expression, presumably derived from the transplanted F3.BDNF. Taken together, these results provide strong evidence that human neural stem cells (F3.BDNF) are effective in treating stroke animal models.

  4. Pathological effects of obstructive apneas during the sleep cycle in an animal model of cerebral small vessel disease.

    Science.gov (United States)

    Lloyd, Eric E; Durgan, David J; Martini, Sharyl R; Bryan, Robert M

    2015-10-01

    We tested the hypothesis that apneas during the sleep cycle exacerbate hypertension and accelerate changes that occur with cerebral small vessel disease. Obstructive sleep apnea was modeled by intermittent inflations of a chronically implanted tracheal balloon to occlude the airway during the sleep cycle (termed OSA) in spontaneously hypertensive stroke-prone (SHRSP) rats, a model of cerebral small vessel disease. SHRSP rats and their parent strain, Wistar Kyoto (WKY) rats, were exposed to OSA for 2 weeks (from 9 to 11 or from 18 to 20 weeks). At 9 weeks, hypertension was developing in the SHRSP rats and was firmly established by 18 weeks. OSA exposure increased systolic blood pressure in SHRSP rats by ≈30 mm Hg in both age groups compared with shams that were surgically prepared but not exposed to OSA (P<0.05). OSA exposure also increased systolic blood pressure in WKY rats by 20 and 37 mm Hg at 11 and 20 weeks, respectively (P<0.05). OSA exposure in SHRSP rats compromised blood-brain barrier integrity in white matter at both 11 and 20 weeks of age when compared with SHRSP sham rats (P<0.05). Microglia were activated in SHRSP rats exposed to OSA but not in sham rats at 11 weeks (P<0.05). At 20 weeks, microglia were activated in sham SHRSP rats (P<0.05) compared with WKY sham rats and were not further activated by OSA. Neither was blood-brain barrier integrity altered nor microglia activated in any of the WKY groups. We conclude that OSA accelerates the onset of the cerebral pathologies associated with cerebral small vessel disease in SHRSP, but not WKY, rats. © 2015 American Heart Association, Inc.

  5. Numerical modeling of in-vessel melt water interaction in large scale PWR`s

    Energy Technology Data Exchange (ETDEWEB)

    Kolev, N.I. [Siemens AG, KWU NA-M, Erlangen (Germany)

    1998-01-01

    This paper presents a comparison between IVA4 simulations and FARO L14, L20 experiments. Both experiments were performed with the same geometry but under different initial pressures, 51 and 20 bar respectively. A pretest prediction for test L21 which is intended to be performed under an initial pressure of 5 bar is also presented. The strong effect of the volume expansion of the evaporating water at low pressure is demonstrated. An in-vessel simulation for a 1500 MW el. PWR is presented. The insight gained from this study is: that at no time are conditions for the feared large scale melt-water intermixing at low pressure in force, with this due to the limiting effect of the expansion process which accelerates the melt and the water into all available flow paths. (author)

  6. Model tests on resistance and seakeeping performance of wave-piercing high-speed vessel with spray rails

    Directory of Open Access Journals (Sweden)

    Jeonghwa Seo

    2016-09-01

    Full Text Available The resistance and seakeeping performance of a high-speed monohull vessel were investigated through a series of model tests in a towing tank. The hull had a slender wave-piercing bow, round bilge, and small deadrise angle on stern. Tests on the bare hull in calm water were first conducted and tests on spray rails followed. The spray rails were designed to control the flow direction and induce a hydrodynamic lift force on the hull bottom to reduce trim angle and increase rise of the hull. The maximum trim of the bare hull was 4.65° at the designed speed, but the spray rails at optimum location reduced trim by 0.97°. The ship motion in head seas was examined after the calm water tests. Attaching the rails on the optimum location effectively reduced the pitch and heave motion responses. The vertical acceleration at the fore perpendicular reduced by 11.3%. The effective power in full scale was extrapolated from the model test results and it was revealed that the spray rails did not have any negative effects on the resistance performance of the hull, while they effectively stabilized the vessel in calm water and waves.

  7. Noninvasive magnetic resonance imaging of vessels affected by transplant arteriosclerosis in an experimental mouse aortic allograft model.

    Science.gov (United States)

    Gebhardt, J; Budinsky, L; Reulbach, U; Weyand, M; Hess, A; Ensminger, S M

    2011-03-01

    Transplant arteriosclerosis is still the leading cause of late mortality after heart transplantation despite advances in immunosuppression regimes. Experimental mouse models have substantially contributed to a better understanding of the multifactorial pathogenesis, but the major limitation of these studies is the difficulty in monitoring progression of transplant arteriosclerosis over time. Therefore, the aim of this study was to investigate whether MR measurements are sensitive enough to detect characteristic vascular lesions in a small animal transplantation model. For this purpose we investigated 22 iso- and allogeneic aortic graft transplanted mice in vivo with a 4.7 T MR scanner using a 2D-RARE technique, 3D time-of-flight angiography and 3D phase contrast angiography as well as a special snake-based reconstruction algorithm. The MR lumen values of patency from native images and from 3D vessel reconstructions of the respective methods were correlated with conventional histological analysis. A comparison of the different techniques showed that angiographic MR modalities correlated well with histological measurements. 2D-RARE sequences were inferior to the sequences obtained by other ones. Superior correlations and the most accurate results were found for vessel reconstruction based on 3D angiographic time-of-flight data. These data demonstrate that mouse in vivo MR imaging is sensitive enough to detect and quantify vascular changes caused by transplant arteriosclerosis. © Georg Thieme Verlag KG Stuttgart · New York.

  8. Compliance with occlusion therapy for childhood amblyopia.

    Science.gov (United States)

    Wallace, Michael P; Stewart, Catherine E; Moseley, Merrick J; Stephens, David A; Fielder, Alistair R

    2013-09-17

    Explore compliance with occlusion treatment of amblyopia in the Monitored and Randomized Occlusion Treatment of Amblyopia Studies (MOTAS and ROTAS), using objective monitoring. Both studies had a three-phase protocol: initial assessment, refractive adaptation, and occlusion. In the occlusion phase, participants were instructed to dose for 6 hours/day (MOTAS) or randomized to 6 or 12 hour/day (ROTAS). Dose was monitored continuously using an occlusion dose monitor (ODM). One hundred and fifty-two patients (71 male, 81 female; 122 Caucasian, 30 non-Caucasian) of mean ± SD age 68 ± 18 months participated. Amblyopia was defined as an interocular acuity difference of at least 0.1 logMAR and was associated with anisometropia in 50, strabismus in 44, and both (mixed) in 58. Median duration of occlusion was 99 days (interquartile range 72 days). Mean compliance was 44%, mean proportion of days with no patch worn was 42%. Compliance was lower (39%) on weekends compared with weekdays (46%, P = 0.04), as was the likelihood of dosing at all (52% vs. 60%, P = 0.028). Compliance was lower when attendance was less frequent (P treatment duration (P amblyopia type, and severity were not associated with compliance. Mixture modeling suggested three subpopulations of patch day doses: less than 30 minutes; doses that achieve 30% to 80% compliance; and doses that achieve around 100% compliance. This study shows that compliance with patching treatment averages less than 50% and is influenced by several factors. A greater understanding of these influences should improve treatment outcome. (ClinicalTrials.gov number, NCT00274664).

  9. Proximal Bright Vessel Sign on Arterial Spin Labeling Magnetic Resonance Imaging in Acute Cardioembolic Cerebral Infarction.

    Science.gov (United States)

    Kato, Ayumi; Shinohara, Yuki; Kuya, Keita; Sakamoto, Makoto; Kowa, Hisanori; Ogawa, Toshihide

    2017-07-01

    The congestion of spin-labeled blood at large-vessel occlusion can present as hyperintense signals on perfusion magnetic resonance imaging with 3-dimensional pseudo-continuous arterial spin labeling (proximal bright vessel sign). The purpose of this study was to clarify the difference between proximal bright vessel sign and susceptibility vessel sign in acute cardioembolic cerebral infarction. Forty-two patients with cardioembolic cerebral infarction in the anterior circulation territory underwent magnetic resonance imaging including diffusion-weighted imaging, 3-dimensional pseudo-continuous arterial spin labeling perfusion magnetic resonance imaging, T2*-weighted imaging, and 3-dimensional time-of-flight magnetic resonance angiography using a 3-T magnetic resonance scanner. Visual assessments of proximal bright vessel sign and the susceptibility vessel sign were performed by consensus of 2 experienced neuroradiologists. The relationship between these signs and the occlusion site of magnetic resonance angiography was also investigated. Among 42 patients with cardioembolic cerebral infarction, 24 patients showed proximal bright vessel sign (57.1%) and 25 showed susceptibility vessel sign (59.5%). There were 19 cases of proximal bright vessel sign and susceptibility vessel sign-clear, 12 cases of proximal bright vessel sign and susceptibility vessel sign-unclear, and 11 mismatched cases. Four out of 6 patients with proximal bright vessel sign-unclear and susceptibility vessel sign-clear showed distal middle cerebral artery occlusion, and 2 out of 5 patients with proximal bright vessel sign-clear and susceptibility vessel sign-unclear showed no occlusion on magnetic resonance angiography. Proximal bright vessel sign is almost compatible with susceptibility vessel sign in patients with cardioembolic cerebral infarction. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  10. A fast multiparameter MRI approach for acute stroke assessment on a 3T clinical scanner: preliminary results in a non-human primate model with transient ischemic occlusion.

    Science.gov (United States)

    Zhang, Xiaodong; Tong, Frank; Li, Chun-Xia; Yan, Yumei; Nair, Govind; Nagaoka, Tsukasa; Tanaka, Yoji; Zola, Stuart; Howell, Leonard

    2014-04-01

    Many MRI parameters have been explored and demonstrated the capability or potential to evaluate acute stroke injury, providing anatomical, microstructural, functional, or neurochemical information for diagnostic purposes and therapeutic development. However, the application of multiparameter MRI approach is hindered in clinic due to the very limited time window after stroke insult. Parallel imaging technique can accelerate MRI data acquisition dramatically and has been incorporated in modern clinical scanners and increasingly applied for various diagnostic purposes. In the present study, a fast multiparameter MRI approach including structural T1-weighted imaging (T1W), T2-weighted imaging (T2W), diffusion tensor imaging (DTI), T2-mapping, proton magnetic resonance spectroscopy, cerebral blood flow (CBF), and magnetization transfer (MT) imaging, was implemented and optimized for assessing acute stroke injury on a 3T clinical scanner. A macaque model of transient ischemic stroke induced by a minimal interventional approach was utilized for evaluating the multiparameter MRI approach. The preliminary results indicate the surgical procedure successfully induced ischemic occlusion in the cortex and/or subcortex in adult macaque monkeys (n=4). Application of parallel imaging technique substantially reduced the scanning duration of most MRI data acquisitions, allowing for fast and repeated evaluation of acute stroke injury. Hence, the use of the multiparameter MRI approach with up to five quantitative measures can provide significant advantages in preclinical or clinical studies of stroke disease.

  11. PACAP38 differentially effects genes and CRMP2 protein expression in ischemic core and penumbra regions of permanent middle cerebral artery occlusion model mice brain.

    Science.gov (United States)

    Hori, Motohide; Nakamachi, Tomoya; Shibato, Junko; Rakwal, Randeep; Tsuchida, Masachi; Shioda, Seiji; Numazawa, Satoshi

    2014-09-23

    Pituitary adenylate-cyclase activating polypeptide (PACAP) has neuroprotective and axonal guidance functions, but the mechanisms behind such actions remain unclear. Previously we examined effects of PACAP (PACAP38, 1 pmol) injection intracerebroventrically in a mouse model of permanent middle cerebral artery occlusion (PMCAO) along with control saline (0.9% NaCl) injection. Transcriptomic and proteomic approaches using ischemic (ipsilateral) brain hemisphere revealed differentially regulated genes and proteins by PACAP38 at 6 and 24 h post-treatment. However, as the ischemic hemisphere consisted of infarct core, penumbra, and non-ischemic regions, specificity of expression and localization of these identified molecular factors remained incomplete. This led us to devise a new experimental strategy wherein, ischemic core and penumbra were carefully sampled and compared to the corresponding contralateral (healthy) core and penumbra regions at 6 and 24 h post PACAP38 or saline injections. Both reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were used to examine targeted gene expressions and the collapsin response mediator protein 2 (CRMP2) protein profiles, respectively. Clear differences in expression of genes and CRMP2 protein abundance and degradation product/short isoform was observed between ischemic core and penumbra and also compared to the contralateral healthy tissues after PACAP38 or saline treatment. Results indicate the importance of region-specific analyses to further identify, localize and functionally analyse target molecular factors for clarifying the neuroprotective function of PACAP38.

  12. PACAP38 Differentially Effects Genes and CRMP2 Protein Expression in Ischemic Core and Penumbra Regions of Permanent Middle Cerebral Artery Occlusion Model Mice Brain

    Directory of Open Access Journals (Sweden)

    Motohide Hori

    2014-09-01

    Full Text Available Pituitary adenylate-cyclase activating polypeptide (PACAP has neuroprotective and axonal guidance functions, but the mechanisms behind such actions remain unclear. Previously we examined effects of PACAP (PACAP38, 1 pmol injection intracerebroventrically in a mouse model of permanent middle cerebral artery occlusion (PMCAO along with control saline (0.9% NaCl injection. Transcriptomic and proteomic approaches using ischemic (ipsilateral brain hemisphere revealed differentially regulated genes and proteins by PACAP38 at 6 and 24 h post-treatment. However, as the ischemic hemisphere consisted of infarct core, penumbra, and non-ischemic regions, specificity of expression and localization of these identified molecular factors remained incomplete. This led us to devise a new experimental strategy wherein, ischemic core and penumbra were carefully sampled and compared to the corresponding contralateral (healthy core and penumbra regions at 6 and 24 h post PACAP38 or saline injections. Both reverse transcription-polymerase chain reaction (RT-PCR and Western blotting were used to examine targeted gene expressions and the collapsin response mediator protein 2 (CRMP2 protein profiles, respectively. Clear differences in expression of genes and CRMP2 protein abundance and degradation product/short isoform was observed between ischemic core and penumbra and also compared to the contralateral healthy tissues after PACAP38 or saline treatment. Results indicate the importance of region-specific analyses to further identify, localize and functionally analyse target molecular factors for clarifying the neuroprotective function of PACAP38.

  13. Occlusion, TMDs, and dental education

    OpenAIRE

    Ash Major M

    2007-01-01

    Abstract The paradigmatic shift to evidence-based dentistry (EBD) that relates to occlusal therapy, selective occlusal adjustment (OA) and stabilization splints therapy (SS) for TMDs has had an unfavourable impact on the teaching of many of the important aspects of occlusion needed in dental practice. The teaching of OA systematically in dental schools has been nearly abandoned because of the belief that OA is an irreversible procedure and gives the impression that it is without merit elsewhe...

  14. MODEL FOR THE RELIABILITY, AVAILABILITY AND SAFETY OF THE CONTROL CENTERS OF THE VESSEL TRAFFIC MANAGEMENT AND INFORMATION SYSTEMS

    Directory of Open Access Journals (Sweden)

    Pančo Ristov

    2013-07-01

    Full Text Available The quality of Vessel Traffic Management and Information Systems depends on the quality of all subsystems, in particular the quality of control centers. The most commonly used quantitative indicators of the control centers' quality are: reliability, availability, safety, and system failure. Therefore, a block diagram of reliability and the model for reliability / availability (Markov model have been created in this paper and a detailed analysis and calculation of the quantitative indicators of critical components (servers of the control center have been performed. The quality functioning of the control centers will enable gathering, processing, storing and dissemination of timely, safe, and reliable data and information to the services in charge of monitoring and management of maritime traffic.

  15. Virtual occlusal definition for orthognathic surgery.

    Science.gov (United States)

    Liu, X J; Li, Q Q; Zhang, Z; Li, T T; Xie, Z; Zhang, Y

    2016-03-01

    Computer-assisted surgical simulation is being used increasingly in orthognathic surgery. However, occlusal definition is still undertaken using model surgery with subsequent digitization via surface scanning or cone beam computed tomography. A software tool has been developed and a workflow set up in order to achieve a virtual occlusal definition. The results of a validation study carried out on 60 models of normal occlusion are presented. Inter- and intra-user correlation tests were used to investigate the reproducibility of the manual setting point procedure. The errors between the virtually set positions (test) and the digitized manually set positions (gold standard) were compared. The consistency in virtual set positions performed by three individual users was investigated by one way analysis of variance test. Inter- and intra-observer correlation coefficients for manual setting points were all greater than 0.95. Overall, the median error between the test and the gold standard positions was 1.06mm. Errors did not differ among teeth (F=0.371, P>0.05). The errors were not significantly different from 1mm (P>0.05). There were no significant differences in the errors made by the three independent users (P>0.05). In conclusion, this workflow for virtual occlusal definition was found to be reliable and accurate. Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  16. Computational analysis of the effect of the control model of intraaorta pump on ventricular unloading and vessel response.

    Science.gov (United States)

    Gu, Kaiyun; Chang, Yu; Gao, Bin; Liu, Youjun

    2012-01-01

    The intraaorta pump is a novel left ventricular assist device (LVAD) whose hemodynamic effects on the circulatory system is unknown. This article aims to evaluate the different effects on the circulatory system supported by the intraaorta pump. In this article, the pump is controlled by three control strategies, including the continuous flow method, the constant rotational speed, and the constant pressure head. A cardiovascular pump system, which includes cardiovascular circulation, intraaorta pump, and regulating mechanisms of systemic circulation, has been proposed. Left ventricle pressure (LVP), end-diastolic volume (EDV), and left ventricular external work (LVEW) were used to evaluate the degree of ventricular unloading. The pulsatile index (PI), which is defined as a ratio of pulse pressure and mean arterial pressure (MAP), was used to evaluate the effect of the vessel response by three control strategies. The comparison results showed that LVP and EDV were lower than those measured before the intraaorta pump was implanted. For LVEW, the constant pressure head strategy provided a superior ventricular unloading compared with other strategies. Support of the pump led to the lower pulsatility by the three models. However, the PI of the constant pressure head was the most at 0.37. In conclusion, these results indicate that the intraaorta pump controlled by constant pressure head strategy provides superior ventricular unloading and pulsatility of the vessel.

  17. Analyzing Physiologic occlusion

    Directory of Open Access Journals (Sweden)

    M. Emamie

    1987-08-01

    Full Text Available Generally speaking, when preserving and restoring the gnathostomatic system the dentist controls tooth morphology to insure proper distribution of stress. So, we restore a portion of a tooth or all the teeth in such a manner as to subject the associated parts of the system to the least stress. We evaluate our diagnosis and control it in our treatment. The treatment should be based on the scientific method. We create optimal occlusion or a desirable functional state of the masticatory system.  Many persons with occlusal imperfections will not have symptoms of functional disorders. This is the psychological adaptive capacity of the neuromuscular system, teeth, dental arches, and periodontal tissues.Recent developments in dental material, technology and instruments however, have simplified the taskaf restoring rebuilding and rehabilitating diseased mouths. So, optimum oral health and function should be the prime objective of all treatment procedures. Because the ultimate aim will always be to restore the mouth to health and preserve this status throughout the life of a patient.

  18. Partial Resuscitative Endovascular Balloon Occlusion of the Aorta (P-REBOA) in a Pig Model (Sus scrofa)

    Science.gov (United States)

    2015-09-10

    procedure to limit exsanguination is unclear. We evaluated the impact of P-REBOA on immediate survival in a highly lethal swine liver injury model...Methods: Fifteen Yorkshire-cross swine were anesthetized, instrumented, splenectomized, and subjected to 30 liver amputation . Coagulopathy was created

  19. Graft Flow Unaffected by Full Occlusion of Left Anterior Descending Artery during Coronary Artery Bypass Grafting in a Porcine Model

    DEFF Research Database (Denmark)

    Torstensson, Gustav Nils Johannes; Torp, Thomas Lee; Rasuli-Oskuii, Nader

    2013-01-01

    Background: We investigated in a porcine model whether measuring both the flow distal to an anastomosis and the graft transit time flow (TTF) gives a more accurate picture of the true blood flow in the left anterior descending artery (LAD) than graft TTF measurement alone.Methods: We performed off...

  20. Gender difference in autonomic and hemodynamic reactions to abrupt coronary occlusion.

    Science.gov (United States)

    Airaksinen, K E; Ikäheimo, M J; Linnaluoto, M; Tahvanainen, K U; Huikuri, H V

    1998-02-01

    We sought to determine whether there are gender-related differences in autonomic and hemodynamic responses to abrupt coronary occlusion. The risk of sudden death before hospital admission is higher in men with an acute myocardial infarction. The reasons for this gender-related difference are not well understood. Cardiovascular autonomic regulation modifies the outcome of acute coronary events, and there are gender differences in the autonomic regulation of heart rate (HR) in normal physiologic circumstances. We analyzed the changes in HR, HR variability and blood pressure and the occurrence of ventricular ectopic beats during a 2-min coronary occlusion in 140 men and 65 women referred for single-vessel coronary angioplasty. The ranges of nonspecific responses were determined by analyzing a control group of 19 patients with no ischemia during a 2-min balloon inflation in a totally occluded coronary artery. Women more often had ST segment changes (p < 0.01) and chest pain (p < 0.05) during the occlusion. Significant bradycardia or increase in HR variability as a sign of vagal activation occurred more often in women than in men (31% vs. 13%, p < 0.01 and 25% vs. 11%, p < 0.05, respectively). Coronary occlusion also more often caused (28% vs. 11%, p < 0.01) a decrease in blood pressure in women. The most pronounced female preponderance was in the incidence of Bezold-Jarisch-type reaction (i.e., simultaneous bradycardia and decrease in blood pressure [16% vs. 0.7%, p < 0.0001]). Logistic regression models developed to analyze the significance of gender while controlling for baseline variables and signs of ischemia identified female gender to be an independent predictor of bradycardic reactions (odds ratio [OR] 3.2, 95% confidence interval [CI] 1.4 to 7.7, p < 0.01), hypotensive reactions (OR 2.6, 95% CI 1.1 to 6.0, p < 0.05) and Bezold-Jarisch-type response (OR 22.2, 95% CI 2.5 to 200, p < 0.01). Significance of female gender as a protector against early coronary

  1. Characterization of Nanostructural Features in Irradiated Reactor Pressure Vessel Model Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wirth, B D; Odette, G R; Asoka-Kumar, P; Howell, R H; Sterne, P A

    2001-08-01

    Irradiation embrittlement in nuclear reactor pressure vessel steels results from the formation of a high number density of nanometer-sized copper rich precipitates and sub-nanometer defect-solute clusters. We present results of small angle neutron scattering (SANS) and positron annihilation spectroscopy (PAS) characterization of the nanostructural features formed in binary and ternary Fe-Cu-Mn alloys irradiated at {approx}290 C. These complementary techniques provide insight into the composition and character of both types of nanoscale features. The SANS measurements indicate populations of copper-manganese precipitates and smaller vacancy-copper-manganese clusters. The PAS characterization, including both Doppler broadening and positron lifetime measurements, indicates the presence of essentially defect-free Cu precipitates in the Fe-Cu-Mn alloy and vacancy-copper clusters in the Fe-Cu alloy. Thus the SANS and PAS provide a self-consistent picture of nanostructures composed of copper-rich precipitates and vacancy solute cluster complexes and tend to discount high Fe concentrations in the CRPs.

  2. The Value of 3D Printing Models of Left Atrial Appendage Using Real-Time 3D Transesophageal Echocardiographic Data in Left Atrial Appendage Occlusion: Applications toward an Era of Truly Personalized Medicine.

    Science.gov (United States)

    Liu, Peng; Liu, Rijing; Zhang, Yan; Liu, Yingfeng; Tang, Xiaoming; Cheng, Yanzhen

    The objective of this study was to assess the clinical feasibility of generating 3D printing models of left atrial appendage (LAA) using real-time 3D transesophageal echocardiogram (TEE) data for preoperative reference of LAA occlusion. Percutaneous LAA occlusion can effectively prevent patients with atrial fibrillation from stroke. However, the anatomical structure of LAA is so complicated that adequate information of its structure is essential for successful LAA occlusion. Emerging 3D printing technology has the demonstrated potential to structure more accurately than conventional imaging modalities by creating tangible patient-specific models. Typically, 3D printing data sets are acquired from CT and MRI, which may involve intravenous contrast, sedation, and ionizing radiation. It has been reported that 3D models of LAA were successfully created by the data acquired from CT. However, 3D printing of the LAA using real-time 3D TEE data has not yet been explored. Acquisition of 3D transesophageal echocardiographic data from 8 patients with atrial fibrillation was performed using the Philips EPIQ7 ultrasound system. Raw echocardiographic image data were opened in Philips QLAB and converted to 'Cartesian DICOM' format and imported into Mimics® software to create 3D models of LAA, which were printed using a rubber-like material. The printed 3D models were then used for preoperative reference and procedural simulation in LAA occlusion. We successfully printed LAAs of 8 patients. Each LAA costs approximately CNY 800-1,000 and the total process takes 16-17 h. Seven of the 8 Watchman devices predicted by preprocedural 2D TEE images were of the same sizes as those placed in the real operation. Interestingly, 3D printing models were highly reflective of the shape and size of LAAs, and all device sizes predicted by the 3D printing model were fully consistent with those placed in the real operation. Also, the 3D printed model could predict operating difficulty and the

  3. A Hydrodynamic Model of The Human Leg Circulation.

    Science.gov (United States)

    Klabunde, Richard E.; McDowell, Donald E.

    1984-01-01

    Describes the construction and use of a life-size model which shows blood flow under normal and pathological conditions. Four experimental procedures (single vessel occlusion, dilation of distal vascular bed, single artery stenosis, and multiple artery stenoses) typical of those demonstrated by the model are discussed and diagrammed. (DH)

  4. Occlusion, TMDs, and dental education.

    Science.gov (United States)

    Ash, Major M

    2007-01-03

    The paradigmatic shift to evidence-based dentistry (EBD) that relates to occlusal therapy, selective occlusal adjustment (OA) and stabilization splints therapy (SS) for TMDs has had an unfavourable impact on the teaching of many of the important aspects of occlusion needed in dental practice. The teaching of OA systematically in dental schools has been nearly abandoned because of the belief that OA is an irreversible procedure and gives the impression that it is without merit elsewhere in the management of occlusion. However, a particular dose of knowledge and practice of occlusion that is necessary for all aspects of dental care should be taught systematically in dental schools. The uses and misuses of OA and SS and their limitations should be emphasized because of their importance to bring clinical reality into the dental curriculum. Thus, and irrespective of EBD induced contradictions, OA and SS should still have a significant place in systematically teaching of occlusal therapy. However, there are many more aspects of the management of occlusion that should to be considered. Hopefully, because of their importance, other aspects of the management of occlusion will once again become a significant part of the dental curriculum.

  5. [Temporomandibular joint, occlusion and bruxism].

    Science.gov (United States)

    Orthlieb, J D; Ré, J P; Jeany, M; Giraudeau, A

    2016-09-01

    Temporomandibular joint and dental occlusion are joined for better and worse. TMJ has its own weaknesses, sometimes indicated by bad functional habits and occlusal disorders. Occlusal analysis needs to be addressed simply and clearly. The term "malocclusion" is not reliable to build epidemiological studies, etiologic mechanisms or therapeutic advice on this "diagnosis". Understanding the impact of pathogenic malocclusion is not just about occlusal relationships that are more or less defective, it requires to locate them within the skeletal framework, the articular and behavioural context of the patient, and above all to assess their impact on the functions of the masticatory system. The TMJ-occlusion couple is often symbiotic, developing together in relation to its environment, compensating for its own shortcomings. However, a third partner may alter this relationship, such as bruxism, or more generally oral parafunctions, trauma or an interventionist practitioner. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  6. Effects of fatty acid synthase inhibitors on lymphatic vessels: an in vitro and in vivo study in a melanoma model.

    Science.gov (United States)

    Bastos, Débora C; Paupert, Jenny; Maillard, Catherine; Seguin, Fabiana; Carvalho, Marco A; Agostini, Michelle; Coletta, Ricardo D; Noël, Agnès; Graner, Edgard

    2017-02-01

    Fatty acid synthase (FASN) is responsible for the endogenous production of fatty acids from acetyl-CoA and malonyl-CoA. Its overexpression is associated with poor prognosis in human cancers including melanomas. Our group has previously shown that the inhibition of FASN with orlistat reduces spontaneous lymphatic metastasis in experimental B16-F10 melanomas, which is a consequence, at least in part, of the reduction of proliferation and induction of apoptosis. Here, we sought to investigate the effects of pharmacological FASN inhibition on lymphatic vessels by using cell culture and mouse models. The effects of FASN inhibitors cerulenin and orlistat on the proliferation, apoptosis, and migration of human lymphatic endothelial cells (HDLEC) were evaluated with in vitro models. The lymphatic outgrowth was evaluated by using a murine ex vivo assay. B16-F10 melanomas and surgical wounds were produced in the ears of C57Bl/6 and Balb-C mice, respectively, and their peripheral lymphatic vessels evaluated by fluorescent microlymphangiography. The secretion of vascular endothelial growth factor C and D (VEGF-C and -D) by melanoma cells was evaluated by ELISA and conditioned media used to study in vitro lymphangiogenesis. Here, we show that cerulenin and orlistat decrease the viability, proliferation, and migration of HDLEC cells. The volume of lymph node metastases from B16-F10 experimental melanomas was reduced by 39% in orlistat-treated animals as well as the expression of VEGF-C in these tissues. In addition, lymphatic vessels from orlistat-treated mice drained more efficiently the injected FITC-dextran. Orlistat and cerulenin reduced VEGF-C secretion and, increase production of VEGF-D by B16-F10 and SK-Mel-25 melanoma cells. Finally, reduced lymphatic cell extensions, were observed following the treatment with conditioned medium from cerulenin- and orlistat-treated B16-F10 cells. Altogether, our results show that FASN inhibitors have anti-metastatic effects by acting on

  7. Post-injury ex vivo model to investigate effects and toxicity of pharmacological treatment in rings of rabbit aortic vessels.

    Science.gov (United States)

    Finking, G; Wolkenhauer, M; Lenz, C; Hanke, H

    2000-01-01

    Animal experiments are widely accepted in arteriosclerosis research. The aim of the present study was to establish an organ culture model (rings of rabbit aortic vessels) to investigate inhibitory estrogen effects on post injury neointima formation in the vessel wall and to examine whether these effects are cytotoxic. Estrogens are used for secondary prevention of atherosclerosis in postmenopausal women (estrogen replacement therapy/ERT). Phytoestrogens as well as the ovarian 17 beta-estradiol have been demonstrated to inhibit proliferation and migration of vascular smooth muscle cells which are key events in atherogenesis and restenosis after coronary angioplasty. In situ endothelial denudation of the thoracic and abdominal aorta was performed in female rabbits by a 3F Fogarty catheter. Segments of 5 mm were randomized in groups of n = 12 and held in culture. 17 beta-estradiol, Genistein and Daidzein were applied in concentrations of 20 microM, 30 microM, and 40 microM. Groups without estrogen treatment served as controls. The segments were investigated after 21 days. Afterwards, 3 further groups (n = 12) were held with the lowest concentrations of 17 beta-estradiol or the two phytoestrogens having been evaluated to inhibit the neointima formation significantly. After 21 days of treatment these sections were held in medium only for another 7 days to proof whether these segments were still able to proliferate. A denuded control group was held in medium only over 28 days. Compared to controls, 30 microM 17 beta-estradiol, 20 microM Genistein, and 40 microM Daidzein inhibited neointima formation significantly over 21 days. After another 7 days of cultivation in medium only the amount of neointima formation was comparable to that of non-estrogen-treated controls after 21 days. We therefore suggest that the demonstrated inhibitory effect is not explained by toxicity. In conclusion, by the use of this organ culture model it was possible to demonstrate non-toxic post

  8. The impact of vessel size on vulnerability curves: data and models for within-species variability in saplings of aspen, Populus tremuloides Michx.

    Science.gov (United States)

    Cai, Jing; Tyree, Melvin T

    2010-07-01

    The objective of this study was to quantify the relationship between vulnerability to cavitation and vessel diameter within a species. We measured vulnerability curves (VCs: percentage loss hydraulic conductivity versus tension) in aspen stems and measured vessel-size distributions. Measurements were done on seed-grown, 4-month-old aspen (Populus tremuloides Michx) grown in a greenhouse. VCs of stem segments were measured using a centrifuge technique and by a staining technique that allowed a VC to be constructed based on vessel diameter size-classes (D). Vessel-based VCs were also fitted to Weibull cumulative distribution functions (CDF), which provided best-fit values of Weibull CDF constants (c and b) and P(50) = the tension causing 50% loss of hydraulic conductivity. We show that P(50) = 6.166D(-0.3134) (R(2) = 0.995) and that b and 1/c are both linear functions of D with R(2) > 0.95. The results are discussed in terms of models of VCs based on vessel D size-classes and in terms of concepts such as the 'pit area hypothesis' and vessel pathway redundancy.

  9. Neuroprotective Effects of Bone Marrow Mesenchymal Stem Cells on Bilateral Common Carotid Arteries Occlusion Model of Cerebral Ischemia in Rat

    Directory of Open Access Journals (Sweden)

    Bagher Pourheydar

    2016-01-01

    Full Text Available Cell therapy is the most advanced treatment of the cerebral ischemia, nowadays. Herein, we discuss the neuroprotective effects of bone marrow mesenchymal stem cells (BMSCs on rat hippocampal cells following intravenous injection of these cells in an ischemia-reperfusion model. Adult male Wistar rats were divided into 5 groups: control, sham (surgery without blockage of common carotid arteries, ischemia (common carotid arteries were blocked for 30 min prior to reperfusion, vehicle (7 days after ischemia PBS was injected via the tail vein, and treatment (injections of BMSC into the tail veins 7 days after ischemia. We performed neuromuscular and vestibulomotor function tests to assess behavioral function and, finally, brains were subjected to hematoxylin and eosin (H&E, anti-Brdu immunohistochemistry, and TUNEL staining. The ischemia group had severe apoptosis. The group treated with BMSCs had a lower mortality rate and also had significant improvement in functional recovery (P<0.001. Ischemia-reperfusion for 30 min causes damage and extensive neuronal death in the hippocampus, especially in CA1 and CA3 regions, leading to several functional and neurological deficits. In conclusion, intravenous injection of BMSCs can significantly decrease the number of apoptotic neurons and significantly improve functional recovery, which may be a beneficial treatment method for ischemic injuries.

  10. Estimation of Covariances on Prompt Fission Neutron Spectra and Impact of the PFNS Model on the Vessel Fluence

    Directory of Open Access Journals (Sweden)

    Berge Léonie

    2016-01-01

    Full Text Available As the need for precise handling of nuclear data covariances grows ever stronger, no information about covariances of prompt fission neutron spectra (PFNS are available in the evaluated library JEFF-3.2, although present in ENDF/B-VII.1 and JENDL-4.0 libraries for the main fissile isotopes. The aim of this work is to provide an estimation of covariance matrices related to PFNS, in the frame of some commonly used models for the evaluated files, such as the Maxwellian spectrum, the Watt spectrum, or the Madland-Nix spectrum. The evaluation of PFNS through these models involves an adjustment of model parameters to available experimental data, and the calculation of the spectrum variance-covariance matrix arising from experimental uncertainties. We present the results for thermal neutron induced fission of 235U. The systematic experimental uncertainties are propagated via the marginalization technique available in the CONRAD code. They are of great influence on the final covariance matrix, and therefore, on the spectrum uncertainty band width. In addition to this covariance estimation work, we have also investigated the importance on a reactor calculation of the fission spectrum model choice. A study of the vessel fluence depending on the PFNS model is presented. This is done through the propagation of neutrons emitted from a fission source in a simplified PWR using the TRIPOLI-4® code. This last study includes thermal fission spectra from the FIFRELIN Monte-Carlo code dedicated to the simulation of prompt particles emission during fission.

  11. An adaptive occlusion culling algorithm for use in large ves

    DEFF Research Database (Denmark)

    Bormann, Karsten

    2000-01-01

    The Hierarchical Occlusion Map algorithm is combined with Frustum Slicing to give a simpler occlusion-culling algorithm that more adequately caters to large, open VEs. The algorithm adapts to the level of visual congestion and is well suited for use with large, complex models with long mean free...... line of sight ('the great outdoors'), models for which it is not feasible to construct, or search, a database of occluders to be rendered each frame....

  12. Object tracking by occlusion detection via structured sparse learning

    KAUST Repository

    Zhang, Tianzhu

    2013-06-01

    Sparse representation based methods have recently drawn much attention in visual tracking due to good performance against illumination variation and occlusion. They assume the errors caused by image variations can be modeled as pixel-wise sparse. However, in many practical scenarios these errors are not truly pixel-wise sparse but rather sparsely distributed in a structured way. In fact, pixels in error constitute contiguous regions within the object\\'s track. This is the case when significant occlusion occurs. To accommodate for non-sparse occlusion in a given frame, we assume that occlusion detected in previous frames can be propagated to the current one. This propagated information determines which pixels will contribute to the sparse representation of the current track. In other words, pixels that were detected as part of an occlusion in the previous frame will be removed from the target representation process. As such, this paper proposes a novel tracking algorithm that models and detects occlusion through structured sparse learning. We test our tracker on challenging benchmark sequences, such as sports videos, which involve heavy occlusion, drastic illumination changes, and large pose variations. Experimental results show that our tracker consistently outperforms the state-of-the-art. © 2013 IEEE.

  13. Occlusion detection via structured sparse learning for robust object tracking

    KAUST Repository

    Zhang, Tianzhu

    2014-01-01

    Sparse representation based methods have recently drawn much attention in visual tracking due to good performance against illumination variation and occlusion. They assume the errors caused by image variations can be modeled as pixel-wise sparse. However, in many practical scenarios, these errors are not truly pixel-wise sparse but rather sparsely distributed in a structured way. In fact, pixels in error constitute contiguous regions within the object’s track. This is the case when significant occlusion occurs. To accommodate for nonsparse occlusion in a given frame, we assume that occlusion detected in previous frames can be propagated to the current one. This propagated information determines which pixels will contribute to the sparse representation of the current track. In other words, pixels that were detected as part of an occlusion in the previous frame will be removed from the target representation process. As such, this paper proposes a novel tracking algorithm that models and detects occlusion through structured sparse learning. We test our tracker on challenging benchmark sequences, such as sports videos, which involve heavy occlusion, drastic illumination changes, and large pose variations. Extensive experimental results show that our proposed tracker consistently outperforms the state-of-the-art trackers.

  14. Optimal Transport Destination for Ischemic Stroke Patients With Unknown Vessel Status: Use of Prehospital Triage Scores.

    Science.gov (United States)

    Schlemm, Eckhard; Ebinger, Martin; Nolte, Christian H; Endres, Matthias; Schlemm, Ludwig

    2017-08-01

    Patients with acute ischemic stroke (AIS) and large vessel occlusion may benefit from direct transportation to an endovascular capable comprehensive stroke center (mothership approach) as opposed to direct transportation to the nearest stroke unit without endovascular therapy (drip and ship approach). The optimal transport strategy for patients with AIS and unknown vessel status is uncertain. The rapid arterial occlusion evaluation scale (RACE, scores ranging from 0 to 9, with higher scores indicating higher stroke severity) correlates with the National Institutes of Health Stroke Scale and was developed to identify patients with large vessel occlusion in a prehospital setting. We evaluate how the RACE scale can help to inform prehospital triage decisions for AIS patients. In a model-based approach, we estimate probabilities of good outcome (modified Rankin Scale score of ≤2 at 3 months) as a function of severity of stroke symptoms and transport times for the mothership approach and the drip and ship approach. We use these probabilities to obtain optimal RACE cutoff scores for different transfer time settings and combinations of treatment options (time-based eligibility for secondary transfer under the drip and ship approach, time-based eligibility for thrombolysis at the comprehensive stroke center under the mothership approach). In our model, patients with AIS are more likely to benefit from direct transportation to the comprehensive stroke center if they have more severe strokes. Values of the optimal RACE cutoff scores range from 0 (mothership for all patients) to >9 (drip and ship for all patients). Shorter transfer times and longer door-to-needle and needle-to-transfer (door out) times are associated with lower optimal RACE cutoff scores. Use of RACE cutoff scores that take into account transport times to triage AIS patients to the nearest appropriate hospital may lead to improved outcomes. Further studies should examine the feasibility of translation into

  15. Three-Dimensional Rotating Wall Vessel-Derived Cell Culture Models for Studying Virus-Host Interactions

    Directory of Open Access Journals (Sweden)

    Jameson K. Gardner

    2016-11-01

    Full Text Available The key to better understanding complex virus-host interactions is the utilization of robust three-dimensional (3D human cell cultures that effectively recapitulate native tissue architecture and model the microenvironment. A lack of physiologically-relevant animal models for many viruses has limited the elucidation of factors that influence viral pathogenesis and of complex host immune mechanisms. Conventional monolayer cell cultures may support viral infection, but are unable to form the tissue structures and complex microenvironments that mimic host physiology and, therefore, limiting their translational utility. The rotating wall vessel (RWV bioreactor was designed by the National Aeronautics and Space Administration (NASA to model microgravity and was later found to more accurately reproduce features of human tissue in vivo. Cells grown in RWV bioreactors develop in a low fluid-shear environment, which enables cells to form complex 3D tissue-like aggregates. A wide variety of human tissues (from neuronal to vaginal tissue have been grown in RWV bioreactors and have been shown to support productive viral infection and physiological meaningful host responses. The in vivo-like characteristics and cellular features of the human 3D RWV-derived aggregates make them ideal model systems to effectively recapitulate pathophysiology and host responses necessary to conduct rigorous basic science, preclinical and translational studies.

  16. An ultrasound model to calculate the brain blood outflow through collateral vessels: a pilot study

    National Research Council Canada - National Science Library

    Zamboni, Paolo; Sisini, Francesco; Menegatti, Erica; Taibi, Angelo; Malagoni, Anna Maria; Morovic, Sandra; Gambaccini, Mauro

    2013-01-01

    ...), is becoming of prominent interest in clinical practice. We developed a novel model to calculate the cerebral venous return, normalized to the arterial inflow, in the different segments of the IJV...

  17. [A case of occlusal reconstruction for disintegration of occlusion].

    Science.gov (United States)

    Nakamura, Kentaroh

    2006-04-01

    A 70-year-old male patient visited our clinic with the chief complaint of masticatory dysfunction due to ill-fitting upper and lower partial dentures. Serious periodontal disease was observed around the remaining teeth. The occlusal condition was crossbite due to mandibular protrusion, and the occlusal supporting area was classified as Eichner's B-3. A Konus telescopic denture was selected as a prosthesis. Dealing with the increase in occlusal force, the sagittal and lateral imbalances found using the Dental Prescale Occluzer system allowed us to minimize the damage to the prosthesis and effects on abutment teeth and periodontal tissue. It is vital to identify and remove early pathological factors of force in postoperative management to prevent the occurrence of new occlusal collapse in the reconstructed stomatognathic system.

  18. Occlusal considerations in implantology: good occlusal practice in implantology.

    Science.gov (United States)

    Davies, Stephen J

    2010-11-01

    This article is concerned with implants that are being used for fixed crown and bridgework rather than removable prostheses. The huge increase in the provision of implants over the past two decades is set to continue. Most of the research is related to avoiding failures in implants. This research, in the main, has concentrated on the essential interface between the artificial implant and living bone: osseointegration. The other interface, which is worthy of our full attention, is the one between the implant-supported crown and the antagonist tooth: the occlusion. This article aims to provide the basis for guidelines for good occlusal practice in implantology. It will consider these under two headings: those which could be considered as basic occlusal principles; and those occlusal considerations that are specific to implants.

  19. Biomechanics of occlusion--implications for oral rehabilitation.

    Science.gov (United States)

    Peck, C C

    2016-03-01

    The dental occlusion is an important aspect of clinical dentistry; there are diverse functional demands ranging from highly precise tooth contacts to large crushing forces. Further, there are dogmatic, passionate and often diverging views on the relationship between the dental occlusion and various diseases and disorders including temporomandibular disorders, non-carious cervical lesions and tooth movement. This study provides an overview of the biomechanics of the masticatory system in the context of the dental occlusion's role in function. It explores the adaptation and precision of dental occlusion, its role in bite force, jaw movement, masticatory performance and its influence on the oro-facial musculoskeletal system. Biomechanics helps us better understand the structure and function of biological systems and consequently an understanding of the forces on, and displacements of, the dental occlusion. Biomechanics provides insight into the relationships between the dentition, jaws, temporomandibular joints, and muscles. Direct measurements of tooth contacts and forces are difficult, and biomechanical models have been developed to better understand the relationship between the occlusion and function. Importantly, biomechanical research will provide knowledge to help correct clinical misperceptions and inform better patient care. The masticatory system demonstrates a remarkable ability to adapt to a changing biomechanical environment and changes to the dental occlusion or other components of the musculoskeletal system tend to be well tolerated. © 2015 John Wiley & Sons Ltd.

  20. Modeling flow stress constitutive behavior of SA508-3 steel for nuclear reactor pressure vessels

    Science.gov (United States)

    Sun, Mingyue; Hao, Luhan; Li, Shijian; Li, Dianzhong; Li, Yiyi

    2011-11-01

    Based on the measured stress-strain curves under different temperatures and strain rates, a series of flow stress constitutive equations for SA508-3 steel were firstly established through the classical theories on work hardening and softening. The comparison between the experimental and modeling results has confirmed that the established constitutive equations can correctly describe the mechanical responses and microstructural evolutions of the steel under various hot deformation conditions. We further represented a successful industrial application of this model to simulate a forging process for a large conical shell used in a nuclear steam generator, which evidences its practical and promising perspective of our model with an aim of widely promoting the hot plasticity processing for heavy nuclear components of fission reactors.

  1. Permanent occlusion of feeding arteries and draining veins in solid mouse tumors by vascular targeted photodynamic therapy (VTP with Tookad.

    Directory of Open Access Journals (Sweden)

    Noa Madar-Balakirski

    Full Text Available BACKGROUND: Antiangiogenic and anti-vascular therapies present intriguing alternatives to cancer therapy. However, despite promising preclinical results and significant delays in tumor progression, none have demonstrated long-term curative features to date. Here, we show that a single treatment session of Tookad-based vascular targeted photodynamic therapy (VTP promotes permanent arrest of tumor blood supply by rapid occlusion of the tumor feeding arteries (FA and draining veins (DV, leading to tumor necrosis and eradication within 24-48 h. METHODOLOGY/PRINCIPAL FINDINGS: A mouse earlobe MADB106 tumor model was subjected to Tookad-VTP and monitored by three complementary, non-invasive online imaging techniques: Fluorescent intravital microscopy, Dynamic Light Scattering Imaging and photosensitized MRI. Tookad-VTP led to prompt tumor FA vasodilatation (a mean volume increase of 70% with a transient increase (60% in blood-flow rate. Rapid vasoconstriction, simultaneous blood clotting, vessel permeabilization and a sharp decline in the flow rates then followed, culminating in FA occlusion at 63.2 sec+/-1.5SEM. This blockage was deemed irreversible after 10 minutes of VTP treatment. A decrease in DV blood flow was demonstrated, with a slight lag from FA response, accompanied by frequent changes in flow direction before reaching a complete standstill. In contrast, neighboring, healthy tissue vessels of similar sizes remained intact and functional after Tookad-VTP. CONCLUSION/SIGNIFICANCE: Tookad-VTP selectively targets the tumor feeding and draining vessels. To the best of our knowledge, this is the first mono-therapeutic modality that primarily aims at the larger tumor vessels and leads to high cure rates, both in the preclinical and clinical arenas.

  2. The perfusion pattern in coronary artery occlusion: comparison of exercise and adenosine.p6.

    Science.gov (United States)

    Iskandrian, A S; Kegel, J; Heo, J; Ogilby, J D; Untereker, W J; Cave, V

    1992-12-01

    This study compared exercise to adenosine thallium-201 single photon emission computed tomography in detecting occlusion of left anterior descending or right coronary arteries in patients with no previous myocardial infarction. There were 41 patients who underwent adenosine thallium imaging (adenosine infusion at a rate of 140 micrograms/kg/min for 6 min), and 143 patients who underwent exercise thallium imaging. There were more patients with right coronary than left anterior descending coronary artery occlusion. Thus, in the adenosine group, there were 15 patients with left anterior descending artery occlusion, and 26 with right coronary artery occlusion, and in the exercise group, there were 46 patients with left anterior descending artery occlusion, and 97 patients with right coronary artery occlusion. In the adenosine group, the thallium images were abnormal in 41 patients (100%), while in the exercise group, the thallium images were abnormal in 125 patients (87%, P exercise group (P:NS). In patients with isolated single vessel occlusion, the size of the perfusion abnormality was 28 +/- 9% with adenosine, and 21 +/- 12% with exercise (P:NS). Thus, most patients with occlusion of the left anterior descending or right coronary artery have regional perfusion abnormality during stress; the different role of collaterals with each type of stress may explain the higher percentage of abnormal results with adenosine than exercise.

  3. Acute Effects of High Intensity Focused Ultrasound on Blood Vessels In Vivo

    Science.gov (United States)

    Davis, Sara; Raymond, Jason; Church, Charles

    2006-05-01

    The objective was to conduct a parameter study to examine how High Intensity Focused Ultrasound (HIFU) acoustic variables such as frequency, power, pulse duration, and duty cycle affect vascular occlusion in intact arteries. We used the New Zealand rabbit ear model and varied the ultrasound parameters using a dose-escalation approach. In each experiment, the animal's central auricular artery was exposed to HIFU. Frequency (2.2-4.7 MHz), power (10-87 W applied electrical power), pulse duration (5-20s), and duty cycle (5-100%) were varied to determine the optimal conditions for reducing/stopping arterial blood flow. In each experiment, the HIFU applicator was mechanically positioned above the target vessel and blood flow was monitored before and after HIFU treatment using Ultrasound Doppler and Laser Doppler Velocimetry. Vessel damage was confirmed with post-treatment histology. Results show that higher frequencies (3.5 MHz and 4.7 MHz) yielded occlusion more often than the lower frequency transducer (2.2 MHz). The results for lower duty-cycle sonications revealed that occlusion could be achieved at a duty cycle as low as 60%. We conclude that for vessels with minimal adjacent connective tissue, such as in the rabbit ear, HIFU treatments delivered at lower frequencies are less effective than treatments delivered at higher frequencies. Additionally, although the majority of exposures to date have been made using continuous-wave ultrasound, our results suggest that it is possible to achieve favorable results using lower duty-cycle (pulsed) exposures.

  4. Measuring optical properties of a blood vessel model using optical coherence tomography

    Science.gov (United States)

    Levitz, David; Hinds, Monica T.; Tran, Noi; Vartanian, Keri; Hanson, Stephen R.; Jacques, Steven L.

    2006-02-01

    In this paper we develop the concept of a tissue-engineered optical phantom that uses engineered tissue as a phantom for calibration and optimization of biomedical optics instrumentation. With this method, the effects of biological processes on measured signals can be studied in a well controlled manner. To demonstrate this concept, we attempted to investigate how the cellular remodeling of a collagen matrix affected the optical properties extracted from optical coherence tomography (OCT) images of the samples. Tissue-engineered optical phantoms of the vascular system were created by seeding smooth muscle cells in a collagen matrix. Four different optical properties were evaluated by fitting the OCT signal to 2 different models: the sample reflectivity ρ and attenuation parameter μ were extracted from the single scattering model, and the scattering coefficient μ s and root-mean-square scattering angle θ rms were extracted from the extended Huygens-Fresnel model. We found that while contraction of the smooth muscle cells was clearly evident macroscopically, on the microscopic scale very few cells were actually embedded in the collagen. Consequently, no significant difference between the cellular and acellular samples in either set of measured optical properties was observed. We believe that further optimization of our tissue-engineering methods is needed in order to make the histology and biochemistry of the cellular samples sufficiently different from the acellular samples on the microscopic level. Once these methods are optimized, we can better verify whether the optical properties of the cellular and acellular collagen samples differ.

  5. Nanostructure evolution under irradiation of Fe(C)MnNi model alloys for reactor pressure vessel steels

    Energy Technology Data Exchange (ETDEWEB)

    Chiapetto, M., E-mail: mchiapet@sckcen.be [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium); Unité Matériaux Et Transformations (UMET), UMR 8207, Université de Lille 1, ENSCL, F-59600 Villeneuve d’Ascq Cedex (France); Becquart, C.S. [Unité Matériaux Et Transformations (UMET), UMR 8207, Université de Lille 1, ENSCL, F-59600 Villeneuve d’Ascq Cedex (France); Laboratoire commun EDF-CNRS Etude et Modélisation des Microstructures pour le Vieillissement des Matériaux (EM2VM) (France); Domain, C. [EDF R& D, Département Matériaux et Mécanique des Composants, Les Renardières, F-77250 Moret sur Loing (France); Laboratoire commun EDF-CNRS Etude et Modélisation des Microstructures pour le Vieillissement des Matériaux (EM2VM) (France); Malerba, L. [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium)

    2015-06-01

    Radiation-induced embrittlement of bainitic steels is one of the most important lifetime limiting factors of existing nuclear light water reactor pressure vessels. The primary mechanism of embrittlement is the obstruction of dislocation motion produced by nanometric defect structures that develop in the bulk of the material due to irradiation. The development of models that describe, based on physical mechanisms, the nanostructural changes in these types of materials due to neutron irradiation are expected to help to better understand which features are mainly responsible for embrittlement. The chemical elements that are thought to influence most the response under irradiation of low-Cu RPV steels, especially at high fluence, are Ni and Mn, hence there is an interest in modelling the nanostructure evolution in irradiated FeMnNi alloys. As a first step in this direction, we developed sets of parameters for object kinetic Monte Carlo (OKMC) simulations that allow this to be done, under simplifying assumptions, using a “grey alloy” approach that extends the already existing OKMC model for neutron irradiated Fe–C binary alloys [1]. Our model proved to be able to describe the trend in the buildup of irradiation defect populations at the operational temperature of LWR (∼300 °C), in terms of both density and size distribution of the defect cluster populations, in FeMnNi model alloys as compared to Fe–C. In particular, the reduction of the mobility of point-defect clusters as a consequence of the presence of solutes proves to be key to explain the experimentally observed disappearance of detectable point-defect clusters with increasing solute content.

  6. Stress categorization in nozzle to pressure vessel connections finite elements models; Categorizacao de tensoes em modelos de elementos finitos de conexoes bocal-vaso de pressao

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, Levi Barcelos de

    1999-07-01

    The ASME Boiler and Pressure Vessel Code, Section III , is the most important code for nuclear pressure vessels design. Its design criteria were developed to preclude the various pressure vessel failure modes throughout the so-called 'Design by Analysis', some of them by imposing stress limits. Thus, failure modes such as plastic collapse, excessive plastic deformation and incremental plastic deformation under cyclic loading (ratchetting) may be avoided by limiting the so-called primary and secondary stresses. At the time 'Design by Analysis' was developed (early 60's) the main tool for pressure vessel design was the shell discontinuity analysis, in which the results were given in membrane and bending stress distributions along shell sections. From that time, the Finite Element Method (FEM) has had a growing use in pressure vessels design. In this case, the stress results are neither normally separated in membrane and bending stress nor classified in primary and secondary stresses. This process of stress separation and classification in Finite Element (FE) results is what is called stress categorization. In order to perform the stress categorization to check results from FE models against the ASME Code stress limits, mainly from 3D solid FE models, several research works have been conducted. This work is included in this effort. First, a description of the ASME Code design criteria is presented. After that, a brief description of how the FEM can be used in pressure vessel design is showed. Several studies found in the literature on stress categorization for pressure vessel FE models are reviewed and commented. Then, the analyses done in this work are presented in which some typical nozzle to pressure vessel connections subjected to internal pressure and concentrated loads were modeled with solid finite elements. The results from linear elastic and limit load analyses are compared to each other and also with the results obtained by formulae

  7. Computerized occlusal analysis in bruxism

    Directory of Open Access Journals (Sweden)

    Lazić Vojkan

    2006-01-01

    Full Text Available Introduction. Sleep bruxism as nocturnal parafunction, also known as tooth grinding, is the most common parasomnia (sleep disorder. Most tooth grinding occurs during rapid eye movement - REM sleep. Sleep bruxism is an oral habit characterized by rhythmic activity of the masticatory muscles (m. masseter that causes forced contact between dental surfaces during sleep. Sleep bruxism has been associated with craniomandibular disorders including temporomandibular joint discomfort, pulpalgia, premature loss of teeth due to excessive attrition and mobility, headache, muscle ache, sleep interruption of an individual and problems with removable and fixed denture. Basically, two groups of etiological factors can be distinguished, viz., peripheral (occlusal factors and central (pathophysiological and psychological factors. The role of occlusion (occlusal discrepancies as the causative factor is not enough mentioned in relation to bruxism. Objective. The main objective of this paper was to evaluate the connection between occlusal factors and nocturnal parafunctional activities (occlusal disharmonies and bruxism. Method. Two groups were formed- experimental of 15 persons with signs and symptoms of nocturnal parafunctional activity of mandible (mean age 26.6 years and control of 42 persons with no signs and symptoms of bruxism (mean age 26.3 yrs.. The computerized occlusal analyses were performed using the T-Scan II system (Tekscan, Boston, USA. 2D occlusograms were analyzed showing the occlusal force, the center of the occlusal force with the trajectory and the number of antagonistic tooth contacts. Results. Statistically significant difference of force distribution was found between the left and the right side of the arch (L%-R% (t=2.773; p<0.02 in the group with bruxism. The difference of the centre of occlusal force - COF trajectory between the experimental and control group was not significant, but the trajectory of COF was longer in the group of

  8. The determinants of fishing vessel accident severity.

    Science.gov (United States)

    Jin, Di

    2014-05-01

    The study examines the determinants of fishing vessel accident severity in the Northeastern United States using vessel accident data from the U.S. Coast Guard for 2001-2008. Vessel damage and crew injury severity equations were estimated separately utilizing the ordered probit model. The results suggest that fishing vessel accident severity is significantly affected by several types of accidents. Vessel damage severity is positively associated with loss of stability, sinking, daytime wind speed, vessel age, and distance to shore. Vessel damage severity is negatively associated with vessel size and daytime sea level pressure. Crew injury severity is also positively related to the loss of vessel stability and sinking. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Intravitreal NGF administration counteracts retina degeneration after permanent carotid artery occlusion in rat

    Directory of Open Access Journals (Sweden)

    De Sordi Nadia

    2009-05-01

    Full Text Available Abstract Background The neurotrophin nerve growth factor (NGF is produced by different cell types in the anterior and posterior eye, exerting a neuroprotective role in the adult life. The visual system is highly sensitive to NGF and the retina and optic nerve provides suitable subjects for the study of central nervous system degeneration. The model of bilateral carotid occlusion (two-vessel occlusion, 2VO is a well-established model for chronic brain hypoperfusion leading to brain capillary pathology, to retina and optic nerve degeneration. In order to study if a single intravitreal injection of NGF protects the retina and the optic nerve from degeneration during systemic circulatory diseases, we investigated morphological and molecular changes occurring in the retina and optic nerve of adult rats at different time-points (8, 30 and 75 days after bilateral carotid occlusion. Results We demonstrated that a single intravitreal injection of NGF (5 μg/3 μl performed 24 hours after 2VO ligation has a long-lasting protective effect on retina and optic nerve degeneration. NGF counteracts retinal ganglion cells degeneration by early affecting Bax/Bcl-2 balance- and c-jun- expression (at 8 days after 2VO. A single intravitreal NGF injection regulates the demyelination/remyelination balance after ischemic injury in the optic nerve toward remyelination (at 75 days after 2VO, as indicated by the MBP expression regulation, thus preventing optic nerve atrophy and ganglion cells degeneration. At 8 days, NGF does not modify 2VO-induced alteration in VEFG and related receptors mRNA expression. Conclusion The protective effect of exogenous NGF during this systemic circulatory disease seems to occur also by strengthening the effect of endogenous NGF, the synthesis of which is increased by vascular defect and also by the mechanical lesion associated with NGF or even vehicle intraocular delivery.

  10. Modeling of Late Blooming Phases and Precipitation Kinetics in Aging Reactor Pressure Vessel (RPV) Steels

    Energy Technology Data Exchange (ETDEWEB)

    Yongfeng Zhang; Pritam Chakraborty; S. Bulent Biner

    2013-09-01

    The principle work at the atomic scale is to develop a predictive quantitative model for the microstructure evolution of RPV steels under thermal aging and neutron radiation. We have developed an AKMC method for the precipitation kinetics in bcc-Fe, with Cu, Ni, Mn and Si being the alloying elements. In addition, we used MD simulations to provide input parameters (if not available in literature). MMC simulations were also carried out to explore the possible segregation/precipitation morphologies at the lattice defects. First we briefly describe each of the simulation algorithms, then will present our results.

  11. Unraveling the Specific Ischemic Core and Penumbra Transcriptome in the Permanent Middle Cerebral Artery Occlusion Mouse Model Brain Treated with the Neuropeptide PACAP38

    Directory of Open Access Journals (Sweden)

    Motohide Hori

    2015-01-01

    Full Text Available Our group has been systematically investigating the effects of the neuropeptide pituitary adenylate-cyclase activating polypeptide (PACAP on the ischemic brain. To do so, we have established and utilized the permanent middle cerebral artery occlusion (PMCAO mouse model, in which PACAP38 (1 pmol injection is given intracerebroventrically and compared to a control saline (0.9% sodium chloride, NaCl injection, to unravel genome‑wide gene expression changes using a high-throughput DNA microarray analysis approach. In our previous studies, we have accumulated a large volume of data (gene inventory from the whole brain (ipsilateral and contralateral hemispheres after both PMCAO and post-PACAP38 injection. In our latest research, we have targeted specifically infarct or ischemic core (hereafter abbreviated IC and penumbra (hereafter abbreviated P post-PACAP38 injections in order to re-examine the transcriptome at 6 and 24 h post injection. The current study aims to delineate the specificity of expression and localization of differentially expressed molecular factors influenced by PACAP38 in the IC and P regions. Utilizing the mouse 4 × 44 K whole genome DNA chip we show numerous changes (≧/≦ 1.5/0.75-fold at both 6 h (654 and 456, and 522 and 449 up- and down-regulated genes for IC and P, respectively and 24 h (2568 and 2684, and 1947 and 1592 up- and down-regulated genes for IC and P, respectively after PACAP38 treatment. Among the gene inventories obtained here, two genes, brain-derived neurotrophic factor (Bdnf and transthyretin (Ttr were found to be induced by PACAP38 treatment, which we had not been able to identify previously using the whole hemisphere transcriptome analysis. Using bioinformatics analysis by pathway- or specific-disease-state focused gene classifications and Ingenuity Pathway Analysis (IPA the differentially expressed genes are functionally classified and discussed. Among these, we specifically discuss some novel and

  12. Unraveling the Specific Ischemic Core and Penumbra Transcriptome in the Permanent Middle Cerebral Artery Occlusion Mouse Model Brain Treated with the Neuropeptide PACAP38.

    Science.gov (United States)

    Hori, Motohide; Nakamachi, Tomoya; Shibato, Junko; Rakwal, Randeep; Shioda, Seiji; Numazawa, Satoshi

    2015-01-21

    Our group has been systematically investigating the effects of the neuropeptide pituitary adenylate-cyclase activating polypeptide (PACAP) on the ischemic brain. To do so, we have established and utilized the permanent middle cerebral artery occlusion (PMCAO) mouse model, in which PACAP38 (1 pmol) injection is given intracerebroventrically and compared to a control saline (0.9% sodium chloride, NaCl) injection, to unravel genome‑wide gene expression changes using a high-throughput DNA microarray analysis approach. In our previous studies, we have accumulated a large volume of data (gene inventory) from the whole brain (ipsilateral and contralateral hemispheres) after both PMCAO and post-PACAP38 injection. In our latest research, we have targeted specifically infarct or ischemic core (hereafter abbreviated IC) and penumbra (hereafter abbreviated P) post-PACAP38 injections in order to re-examine the transcriptome at 6 and 24 h post injection. The current study aims to delineate the specificity of expression and localization of differentially expressed molecular factors influenced by PACAP38 in the IC and P regions. Utilizing the mouse 4 × 44 K whole genome DNA chip we show numerous changes (≧/≦ 1.5/0.75-fold) at both 6 h (654 and 456, and 522 and 449 up- and down-regulated genes for IC and P, respectively) and 24 h (2568 and 2684, and 1947 and 1592 up- and down-regulated genes for IC and P, respectively) after PACAP38 treatment. Among the gene inventories obtained here, two genes, brain-derived neurotrophic factor (Bdnf) and transthyretin (Ttr) were found to be induced by PACAP38 treatment, which we had not been able to identify previously using the whole hemisphere transcriptome analysis. Using bioinformatics analysis by pathway- or specific-disease-state focused gene classifications and Ingenuity Pathway Analysis (IPA) the differentially expressed genes are functionally classified and discussed. Among these, we specifically discuss some novel and previously

  13. Development of occlusive neointimal lesions in distal pulmonary arteries of endothelin B receptor-deficient rats: a new model of severe pulmonary arterial hypertension.

    Science.gov (United States)

    Ivy, D Dunbar; McMurtry, Ivan F; Colvin, Kelley; Imamura, Masatoshi; Oka, Masahiko; Lee, Dong-Seok; Gebb, Sarah; Jones, Peter Lloyd

    2005-06-07

    Human pulmonary arterial hypertension (PAH) is characterized by proliferation of vascular smooth muscle and, in its more severe form, by the development of occlusive neointimal lesions. However, few animal models of pulmonary neointimal proliferation exist, thereby limiting a complete understanding of the pathobiology of PAH. Recent studies of the endothelin (ET) system demonstrate that deficiency of the ET(B) receptor predisposes adult rats to acute and chronic hypoxic PAH, yet these animals fail to develop neointimal lesions. Herein, we determined and thereafter showed that exposure of ET(B) receptor-deficient rats to the endothelial toxin monocrotaline (MCT) leads to the development of neointimal lesions that share hallmarks of human PAH. The pulmonary hemodynamic and morphometric effects of 60 mg/kg MCT in control (MCT(+/+)) and ET(B) receptor-deficient (MCT(sl/sl)) rats at 6 weeks of age were assessed. MCT(sl/sl) rats developed more severe PAH, characterized by elevated pulmonary artery pressure, diminished cardiac output, and right ventricular hypertrophy. In MCT(sl/sl) rats, morphometric evaluation revealed the presence of neointimal lesions within small distal pulmonary arteries, increased medial wall thickness, and decreased arterial-to-alveolar ratio. In keeping with this, barium angiography revealed diminished distal pulmonary vasculature of MCT(sl/sl) rat lungs. Cells within neointimal lesions expressed smooth muscle and endothelial cell markers. Moreover, cells within neointimal lesions exhibited increased levels of proliferation and were located in a tissue microenvironment enriched with vascular endothelial growth factor, tenascin-C, and activated matrix metalloproteinase-9, factors already implicated in human PAH. Finally, assessment of steady state mRNA showed that whereas expression of ET(B) receptors was decreased in MCT(sl/sl) rat lungs, ET(A) receptor expression increased. Deficiency of the ET(B) receptor markedly accelerates the progression of

  14. Development of Occlusive Neointimal Lesions in Distal Pulmonary Arteries of Endothelin B Receptor–Deficient Rats: A New Model of Severe Pulmonary Arterial Hypertension

    Science.gov (United States)

    Ivy, D. Dunbar; McMurtry, Ivan F.; Colvin, Kelley; Imamura, Masatoshi; Oka, Masahiko; Lee, Dong-Seok; Gebb, Sarah; Jones, Peter Lloyd

    2007-01-01

    Background Human pulmonary arterial hypertension (PAH) is characterized by proliferation of vascular smooth muscle and, in its more severe form, by the development of occlusive neointimal lesions. However, few animal models of pulmonary neointimal proliferation exist, thereby limiting a complete understanding of the pathobiology of PAH. Recent studies of the endothelin (ET) system demonstrate that deficiency of the ETB receptor predisposes adult rats to acute and chronic hypoxic PAH, yet these animals fail to develop neointimal lesions. Herein, we determined and thereafter showed that exposure of ETB receptor–deficient rats to the endothelial toxin monocrotaline (MCT) leads to the development of neointimal lesions that share hallmarks of human PAH. Methods and Results The pulmonary hemodynamic and morphometric effects of 60 mg/kg MCT in control (MCT+/+) and ETB receptor–deficient (MCTsl/sl) rats at 6 weeks of age were assessed. MCTsl/sl rats developed more severe PAH, characterized by elevated pulmonary artery pressure, diminished cardiac output, and right ventricular hypertrophy. In MCTsl/sl rats, morphometric evaluation revealed the presence of neointimal lesions within small distal pulmonary arteries, increased medial wall thickness, and decreased arterial-to-alveolar ratio. In keeping with this, barium angiography revealed diminished distal pulmonary vasculature of MCTsl/sl rat lungs. Cells within neointimal lesions expressed smooth muscle and endothelial cell markers. Moreover, cells within neointimal lesions exhibited increased levels of proliferation and were located in a tissue microenvironment enriched with vascular endothelial growth factor, tenascin-C, and activated matrix metalloproteinase-9, factors already implicated in human PAH. Finally, assessment of steady state mRNA showed that whereas expression of ETB receptors was decreased in MCTsl/sl rat lungs, ETA receptor expression increased. Conclusions Deficiency of the ETB receptor markedly

  15. Photometric Ambient Occlusion for Intrinsic Image Decomposition.

    Science.gov (United States)

    Hauagge, Daniel; Wehrwein, Scott; Bala, Kavita; Snavely, Noah

    2016-04-01

    We present a method for computing ambient occlusion (AO) for a stack of images of a Lambertian scene from a fixed viewpoint. Ambient occlusion, a concept common in computer graphics, characterizes the local visibility at a point: it approximates how much light can reach that point from different directions without getting blocked by other geometry. While AO has received surprisingly little attention in vision, we show that it can be approximated using simple, per-pixel statistics over image stacks, based on a simplified image formation model. We use our derived AO measure to compute reflectance and illumination for objects without relying on additional smoothness priors, and demonstrate state-of-the art performance on the MIT Intrinsic Images benchmark. We also demonstrate our method on several synthetic and real scenes, including 3D printed objects with known ground truth geometry.

  16. RTSAH Traversal Order for Occlusion Rays

    KAUST Repository

    Ize, Thiago

    2011-04-01

    We accelerate the finding of occluders in tree based acceleration structures, such as a packetized BVH and a single ray kd-tree, by deriving the ray termination surface area heuristic (RTSAH) cost model for traversing an occlusion ray through a tree and then using the RTSAH to determine which child node a ray should traverse first instead of the traditional choice of traversing the near node before the far node. We further extend RTSAH to handle materials that attenuate light instead of fully occluding it, so that we can avoid superfluous intersections with partially transparent objects. For scenes with high occlusion, we substantially lower the number of traversal steps and intersection tests and achieve up to 2× speedups. © 2010 The Author(s).

  17. Central retinal vein occlusion concomitant with dengue fever.

    Science.gov (United States)

    Velaitham, Punithamalar; Vijayasingham, Nandini

    2016-01-01

    Dengue virus infection is on the rise and there is increasing number of ocular complications that are being reported. Most common ocular complications are macular edema, macular hemorrhages, and foveolitis. There are case reports on branch retinal vessel occlusions. Most of the ocular complications are attributed to the bleeding tendency and transudative process in dengue viral infection. This is a case report of ischemic central retinal vein occlusion (CRVO) concomitant with dengue fever. A 41 year old Malay female was admitted to medical ward and diagnosed to have "dengue fever with warning signs". On the day of admission she noted sudden onset of right eye blurring of vision. She presented to our clinic 1 week later. Ocular examination revealed right eye visual acuity of <20/1000 and ischaemic CRVO with macular edema. She had no other risk factors to develop retinal vein occlusion. She progressively developed proliferative retinopathy and received multiple laser therapy. There was no anterior segment neovascularization. However, her vision improved to only 20/400 despite of resolution of macular edema and new vessels elsewhere. Dengue virus infection is known to cause thrombocytopenia which can result in hemorrhagic events. It can also cause procoagulant state which can result in thrombotic events secondary to immune reaction. Awareness among treating physicians of such ocular complication which can result in significant morbidity for patient is necessary.

  18. An exploration of the reflow technique for the fabrication of an in vitro microvascular system to study occlusive clots.

    Science.gov (United States)

    Li, Yang; Pan, Chuer; Li, Yunfeng; Kumacheva, Eugenia; Ramachandran, Arun

    2017-09-08

    Embolic ischemia and pulmonary embolism are health emergencies that arise when a particle such as a blood clot occludes a smaller blood vessel in the brain or the lungs, and restricts flow of blood downstream of the vessel. In this work, the reflow technique (Wang et al. Biomed. Microdevices 2007, 9, 657) was adapted to produce a microchannel network that mimics the occlusion process. The technique was first revisited and a simple geometrical model was developed to quantitatively explain the shapes of the resulting microchannels for different reflow parameters. A critical modification was introduced to the reflow protocol to fabricate nearly circular microchannels of different diameters from the same master, which is not possible with the traditional reflow technique. To simulate the phenomenon of occlusion by clots, a microchannel network with three generations of branches with different diameters and branching angles was fabricated, into which fibrin clots were introduced. At low constant pressure drop (ΔP), a clot blocked a branch entrance only partially, while at higher ΔP, the branch was completely blocked. Instances of simultaneous blocking of multiple channels by clots, and the consequent changes in the flow rates in the unblocked branches of the network, were also monitored. This work provides the framework for a systematic study of the distribution of clots in a network, and the rate of dissolution of embolic clots upon the introduction of a thrombolytic drug into the network.

  19. Haptic simulation framework for determining virtual dental occlusion.

    Science.gov (United States)

    Wu, Wen; Chen, Hui; Cen, Yuhai; Hong, Yang; Khambay, Balvinder; Heng, Pheng Ann

    2017-04-01

    The surgical treatment of many dentofacial deformities is often complex due to its three-dimensional nature. To determine the dental occlusion in the most stable position is essential for the success of the treatment. Computer-aided virtual planning on individualized patient-specific 3D model can help formulate the surgical plan and predict the surgical change. However, in current computer-aided planning systems, it is not possible to determine the dental occlusion of the digital models in the intuitive way during virtual surgical planning because of absence of haptic feedback. In this paper, a physically based haptic simulation framework is proposed, which can provide surgeons with the intuitive haptic feedback to determine the dental occlusion of the digital models in their most stable position. To provide the physically realistic force feedback when the dental models contact each other during the searching process, the contact model is proposed to describe the dynamic and collision properties of the dental models during the alignment. The simulated impulse/contact-based forces are integrated into the unified simulation framework. A validation study has been conducted on fifteen sets of virtual dental models chosen at random and covering a wide range of the dental relationships found clinically. The dental occlusions obtained by an expert were employed as a benchmark to compare the virtual occlusion results. The mean translational and angular deviations of the virtual occlusion results from the benchmark were small. The experimental results show the validity of our method. The simulated forces can provide valuable insights to determine the virtual dental occlusion. The findings of this work and the validation of proposed concept lead the way for full virtual surgical planning on patient-specific virtual models allowing fully customized treatment plans for the surgical correction of dentofacial deformities.

  20. Non-occlusive mesenteric ischemia: etiology, diagnosis, and interventional therapy

    Energy Technology Data Exchange (ETDEWEB)

    Trompeter, Markus; Brazda, Thurid; Remy, Christopher T.; Reimer, Peter [Department of Radiology, Staedtisches Klinikum Karlsruhe (Germany); Vestring, Thomas [Department of Radiology, Diakonie-Krankenhaus Rotenburg/Wuemme, Goettingen (Germany)

    2002-05-01

    Non-occlusive mesenteric ischemia (NOMI) compromises all forms of mesenteric ischemia with patent mesenteric arteries. It generally affects patients over 50 years of age suffering from myocardial infarction, congestive heart failure, aortic insufficiency, renal or hepatic disease and patients following cardiac surgery. Non-occlusive disease accounts for 20-30% of all cases of acute mesenteric ischemia with a mortality rate of the order of 50%. Acute abdominal pain may be the only early presenting symptom of mesenteric ischemia. Non-invasive imaging modalities, such as CT, MRI, and ultrasound, are able to evaluate the aorta and the origins of splanchnic arteries. Despite the technical evolution of those methods, selective angiography of mesenteric arteries is still the gold standard in diagnosing peripheral splanchnic vessel disease. In early non-occlusive mesenteric ischemia, as opposed to occlusive disease, there is no surgical therapy. It is known that mesenteric vasospasm persists even after correction of the precipitating event. Vasospasm frequently responds to direct intra-arterial vasodilator therapy, which is the only treatment that has been shown to be effective. (orig.)

  1. Blood vessel hyperpermeability and pathophysiology in human tumour xenograft models of breast cancer: a comparison of ectopic and orthotopic tumours

    Directory of Open Access Journals (Sweden)

    Ho Karyn S

    2012-12-01

    Full Text Available Abstract Background Human tumour xenografts in immune compromised mice are widely used as cancer models because they are easy to reproduce and simple to use in a variety of pre-clinical assessments. Developments in nanomedicine have led to the use of tumour xenografts in testing nanoscale delivery devices, such as nanoparticles and polymer-drug conjugates, for targeting and efficacy via the enhanced permeability and retention (EPR effect. For these results to be meaningful, the hyperpermeable vasculature and reduced lymphatic drainage associated with tumour pathophysiology must be replicated in the model. In pre-clinical breast cancer xenograft models, cells are commonly introduced via injection either orthotopically (mammary fat pad, MFP or ectopically (subcutaneous, SC, and the organ environment experienced by the tumour cells has been shown to influence their behaviour. Methods To evaluate xenograft models of breast cancer in the context of EPR, both orthotopic MFP and ectopic SC injections of MDA-MB-231-H2N cells were given to NOD scid gamma (NSG mice. Animals with matched tumours in two size categories were tested by injection of a high molecular weight dextran as a model nanocarrier. Tumours were collected and sectioned to assess dextran accumulation compared to liver tissue as a positive control. To understand the cellular basis of these observations, tumour sections were also immunostained for endothelial cells, basement membranes, pericytes, and lymphatic vessels. Results SC tumours required longer development times to become size matched to MFP tumours, and also presented wide size variability and ulcerated skin lesions 6 weeks after cell injection. The 3 week MFP tumour model demonstrated greater dextran accumulation than the size matched 5 week SC tumour model (for P  Conclusions Dextran accumulation and immunostaining results suggest that small MFP tumours best replicate the vascular permeability required to observe the EPR effect

  2. Toward free-surface modeling of planing vessels: simulation of the Fridsma hull using ALE-VMS

    Science.gov (United States)

    Akkerman, I.; Dunaway, J.; Kvandal, J.; Spinks, J.; Bazilevs, Y.

    2012-12-01

    In this paper we focus on a class of applications involving surface vessels moving at high speeds, or "planing". We introduce a Fridsma planing hull benchmark problem, and simulate it using the finite-element-based ALE-VMS (Bazilevs et al. in Math Models Methods Appl Sci 2012; Takizawa et al. in Arch Comput Methods Eng 19: 171-225, 2012) approach. The major reasons for selecting this problem is the relative simplicity of the hull geometry and the existence of high-quality experimental data used for the purposes of validation. The ALE-VMS approach is formulated in the context of the Mixed Interface-Tracking/Interface-Capturing Technique (MITICT) (Tezduyar in Arch Comput Methods Eng 8:83-130, 2001; Akin et al. in Comput Fluids 36:2-11, 2007; Cruchaga et al. in Int J Numer Methods Fluids 54:1021-1031, 2007), where the level set technique is used for capturing the air-water interface, and the Arbitrary Lagrangian Eulerian (ALE) method is employed to track the interface between the fluid and structure. In this work, the planing hull structure is treated as a six-degree-of-freedom rigid object. The computational results obtained for the Fridsma hull, which include convergence of the trim angle and drag under mesh refinement, match well with the experimental data.

  3. Finite element analysis to estimate burst pressure of mild steel pressure vessel using Ramberg–Osgood model

    Directory of Open Access Journals (Sweden)

    Puneet Deolia

    2016-09-01

    Full Text Available Burst pressure is the pressure at which vessel burst/crack and internal fluid leaks. An accurate prediction of burst pressure is necessary in chemical, medical and aviation industry. Burst pressure is a design safety limit, which should not be exceeded. If this pressure is exceeded it may lead to the mechanical breach and permanent loss of pressure containment. So burst pressure calculation is necessary for all the critical applications. To numerically calculate burst pressure material curve is essential. There are various material models which are used to define material curve, amongst them Ramberg–Osgood is very popular. Ramberg–Osgood accurately capture material curve in strain hardening region. This approach is applicable for different material grades. In this paper a finite element method is used to predict burst pressure using Ramberg–Osgood equation. These results are then compared with results obtained from elasto-plastic curve and true stress strain curve. Results obtained by finite element analysis are validated with experimental data which is considered from open literature.

  4. Local inhibition of elastase reduces EMILIN1 cleavage reactivating lymphatic vessel function in a mouse lymphoedema model.

    Science.gov (United States)

    Pivetta, Eliana; Wassermann, Bruna; Del Bel Belluz, Lisa; Danussi, Carla; Modica, Teresa Maria Elisa; Maiorani, Orlando; Bosisio, Giulia; Boccardo, Francesco; Canzonieri, Vincenzo; Colombatti, Alfonso; Spessotto, Paola

    2016-07-01

    Lymphatic vasculature critically depends on the connections of lymphatic endothelial cells with the extracellular matrix (ECM), which are mediated by anchoring filaments (AFs). The ECM protein EMILIN1 is a component of AFs and is involved in the regulation of lymphatic vessel functions: accordingly, Emilin1(-/-) mice display lymphatic vascular morphological alterations, leading to functional defects such as mild lymphoedema, lymph leakage and compromised lymph drainage. In the present study, using a mouse post-surgical tail lymphoedema model, we show that the acute phase of acquired lymphoedema correlates with EMILIN1 degradation due to neutrophil elastase (NE) released by infiltrating neutrophils. As a consequence, the intercellular junctions of lymphatic endothelial cells are weakened and drainage to regional lymph nodes is severely affected. The local administration of sivelestat, a specific NE inhibitor, prevents EMILIN1 degradation and reduces lymphoedema, restoring a normal lymphatic functionality. The finding that, in human secondary lymphoedema samples, we also detected cleaved EMILIN1 with the typical bands of an NE-dependent pattern of fragmentation establishes a rationale for a powerful strategy that targets NE inhibition. In conclusion, the attempts to block EMILIN1 degradation locally represent the basis for a novel 'ECM' pharmacological approach to assessing new lymphoedema treatments. © 2016 The Author(s).

  5. Differential gene expression in multiple neurological, inflammatory and connective tissue pathways in a spontaneous model of human small vessel stroke.

    Science.gov (United States)

    Bailey, Emma L; McBride, Martin W; Beattie, Wendy; McClure, John D; Graham, Delyth; Dominiczak, Anna F; Sudlow, Cathie L M; Smith, Colin; Wardlaw, Joanna M

    2014-12-01

    Cerebral small vessel disease (SVD) causes a fifth of all strokes plus diffuse brain damage leading to cognitive decline, physical disabilities and dementia. The aetiology and pathogenesis of SVD are unknown, but largely attributed to hypertension or microatheroma. We used the spontaneously hypertensive stroke-prone rat (SHRSP), the closest spontaneous experimental model of human SVD, and age-matched control rats kept under identical, non-salt-loaded conditions, to perform a blinded analysis of mRNA microarray, qRT-PCR and pathway analysis in two brain regions (frontal and mid-coronal) commonly affected by SVD in the SHRSP at age five, 16 and 21 weeks. We found gene expression abnormalities, with fold changes ranging from 2.5 to 59 for the 10 most differentially expressed genes, related to endothelial tight junctions (reduced), nitric oxide bioavailability (reduced), myelination (impaired), glial and microglial activity (increased), matrix proteins (impaired), vascular reactivity (impaired) and albumin (reduced), consistent with protein expression defects in the same rats. All were present at age 5 weeks thus predating blood pressure elevation. 'Neurological' and 'inflammatory' pathways were more affected than 'vascular' functional pathways. This set of defects, although individually modest, when acting in combination could explain the SHRSP's susceptibility to microvascular and brain injury, compared with control rats. Similar combined, individually modest, but multiple neurovascular unit defects, could explain susceptibility to spontaneous human SVD. © 2014 The Authors. Neuropathology and Applied Neurobiology published by John Wiley & Sons Ltd on behalf of British Neuropathological Society.

  6. Blood vessel tortuosity selects against evolution of aggressive tumor cells in confined tissue environments: A modeling approach.

    Directory of Open Access Journals (Sweden)

    András Szabó

    2017-07-01

    Full Text Available Cancer is a disease of cellular regulation, often initiated by genetic mutation within cells, and leading to a heterogeneous cell population within tissues. In the competition for nutrients and growth space within the tumors the phenotype of each cell determines its success. Selection in this process is imposed by both the microenvironment (neighboring cells, extracellular matrix, and diffusing substances, and the whole of the organism through for example the blood supply. In this view, the development of tumor cells is in close interaction with their increasingly changing environment: the more cells can change, the more their environment will change. Furthermore, instabilities are also introduced on the organism level: blood supply can be blocked by increased tissue pressure or the tortuosity of the tumor-neovascular vessels. This coupling between cell, microenvironment, and organism results in behavior that is hard to predict. Here we introduce a cell-based computational model to study the effect of blood flow obstruction on the micro-evolution of cells within a cancerous tissue. We demonstrate that stages of tumor development emerge naturally, without the need for sequential mutation of specific genes. Secondly, we show that instabilities in blood supply can impact the overall development of tumors and lead to the extinction of the dominant aggressive phenotype, showing a clear distinction between the fitness at the cell level and survival of the population. This provides new insights into potential side effects of recent tumor vasculature normalization approaches.

  7. Comparison of the occlusal vertical dimension after processing complete dentures made with lingualized balanced occlusion and conventional balanced occlusion.

    Science.gov (United States)

    Basso, Michael Frederico Manzolli; Nogueira, Sergio Sualdini; Arioli-Filho, Joao Neudenir

    2006-09-01

    An increase in occlusal vertical dimension (OVD) may occur after processing complete dentures. Although many factors that generate this change are known, no information is available in the dental literature regarding the effect that the occlusal scheme may have on the change in OVD. This in vitro study compared the increase in OVD, after processing, between complete dentures with teeth arranged in lingualized balanced occlusion and conventional balanced occlusion. Thirty sets of complete dentures were evaluated as follows: 15 sets of complete dentures were arranged in conventional balanced occlusion (control) and 15 sets of complete dentures were arranged in lingualized balanced occlusion. All dentures were compression molded with a long polymerization cycle. The occlusal vertical dimension was measured with a micrometer (mm) before and after processing each set of dentures. Data were analyzed using an independent t test (alpha=.05). The mean increase in the OVD, after processing, was 0.87 +/- 0.21 mm for the control group and 0.90 +/- 0.27 mm for the experimental group. There was no significant difference between the groups. After processing, dentures set in lingualized balanced occlusion showed an increase in OVD similar to those set in conventional balanced occlusion. Although the 2 occlusal concepts resulted in similar increases in the OVD after processing, the lingualized balanced occlusion may result in easier occlusal adjustments, as the less complicated occlusal scheme uses a smaller number of centric occlusion contact points.

  8. Differential transport function of lymphatic vessels in the rat tail model and the long-term effects of Indocyanine Green as assessed with near-infrared imaging

    Directory of Open Access Journals (Sweden)

    Michael eWeiler

    2013-08-01

    Full Text Available Introduction: Near-infrared (NIR imaging has emerged as a novel imaging modality for assessing lymphatic function in vivo. While the technique has provided quantitative data previously unavailable, questions remain in regards to the spatiotemporal capabilities of the approach. We address three of the more important issues here using the rodent tail, one of the most widely utilized in vivo model systems in the lymphatic literature. Specifically we demonstrate 1 the transient vs. steady state response of lymphatics to tracer injection, 2 the functional characteristics of multiple collecting vessels draining the same tissue space in parallel, and 3 the long-term consequences of fluorescent tracers on lymphatic function to repeated functional measurements.Methods: Rat tails were imaged with NIR and metrics of function were calculated for both collecting vessels that drain the tail. A nitric oxide donor cream (GTNO was applied to the tail. Additionally, two different NIR dyes, indocyanine green (ICG and LI-COR IRDye 800CW PEG, were utilized for function imaging at the time of initial injection and at 1, 2, and 4 week follow-up time points after which both draining lymph nodes were harvested.Results and Discussion: Significant differences were found between the two collecting vessels such that the vessel first showing fluorescence (dominant produced enhanced functional metrics compared to the second vessel (non-dominant. GTNO significantly reduced lymphatic function in the non-dominant vessel compared to the dominant. ICG remained visible in the tail for 2 weeks after injection and was accompanied by significant losses in lymphatic function and enlarged draining lymph nodes. The Licor tracer also remained visible for 2 weeks. However, the dye produced significantly lower effects on lymphatic function than ICG, and lymph nodes were not enlarged at any time point, suggesting that this may be a more appropriate contrast agent for longitudinal lymphatic

  9. Differential transport function of lymphatic vessels in the rat tail model and the long-term effects of Indocyanine Green as assessed with near-infrared imaging.

    Science.gov (United States)

    Weiler, Michael; Dixon, J Brandon

    2013-01-01

    Near-infrared (NIR) imaging has emerged as a novel imaging modality for assessing lymphatic function in vivo. While the technique has provided quantitative data previously unavailable, questions remain in regards to the spatiotemporal capabilities of the approach. We address three of the more important issues here using the rodent tail, one of the most widely utilized in vivo model systems in the lymphatic literature. Specifically we demonstrate (1) the transient vs. steady state response of lymphatics to tracer injection, (2) the functional characteristics of multiple collecting vessels draining the same tissue space in parallel, and (3) the long-term consequences of fluorescent tracers on lymphatic function to repeated functional measurements. Rat tails were imaged with NIR and metrics of function were calculated for both collecting vessels that drain the tail. A nitric oxide donor cream (GTNO) was applied to the tail. Additionally, two different NIR dyes, indocyanine green (ICG) and LI-COR IRDye 800CW PEG, were utilized for function imaging at the time of initial injection and at 1, 2, and 4 week follow-up time points after which both draining lymph nodes were harvested. Significant differences were found between the two collecting vessels such that the vessel first showing fluorescence (dominant) produced enhanced functional metrics compared to the second vessel (non-dominant). GTNO significantly reduced lymphatic function in the non-dominant vessel compared to the dominant. ICG remained visible in the tail for 2 weeks after injection and was accompanied by significant losses in lymphatic function and enlarged draining lymph nodes. The Licor tracer also remained visible for 2 weeks. However, the dye produced significantly lower effects on lymphatic function than ICG, and lymph nodes were not enlarged at any time point, suggesting that this may be a more appropriate contrast agent for longitudinal lymphatic imaging.

  10. Vessel Operator System

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Operator cards are required for any operator of a charter/party boat and or a commercial vessel (including carrier and processor vessels) issued a vessel permit from...

  11. Very Versatile Vessel

    Science.gov (United States)

    2009-09-01

    data. This source provides information on aluminum hydrofoil vessels without the added weight of foil structures. The composite armor around the...seating compartment. The sides should also limit wave splash on the deck. The freeboard should contribute reserve buoyancy , increasing large-angle and...Resistance, Powering, and Propulsion Savitsky’s Method Since model testing data or other reliable performance data was unavailable for the proposed

  12. Developing a Computational Environment for Coupling MOR Data, Maps, and Models: The Virtual Research Vessel (VRV) Prototype

    Science.gov (United States)

    Wright, D. J.; O'Dea, E.; Cushing, J. B.; Cuny, J. E.; Toomey, D. R.; Hackett, K.; Tikekar, R.

    2001-12-01

    The East Pacific Rise (EPR) from 9-10deg. N is currently our best-studied section of fast-spreading mid-ocean ridge. During several decades of investigation it has been explored by the full spectrum of ridge investigators, including chemists, biologists, geologists and geophysicists. These studies, and those that are ongoing, provide a wealth of observational data, results and data-driven theoretical (often numerical) studies that have not yet been fully utilized either by research scientists or by professional educators. While the situation is improving, a large amount of data, results, and related theoretical models still exist either in an inert, non-interactive form (e.g., journal publications) or as unlinked and currently incompatible computer data or algorithms. Infrastructure is needed not just for ready access to data, but linkage of disparate data sets (data to data) as well as data to models in order quantitatively evaluate hypotheses, refine numerical simulations, and explore new relations between observables. The prototype of a computational environment and toolset, called the Virtual Research Vessel (VRV), is being developed to provide scientists and educators with ready access to data, results and numerical models. While this effort is focused on the EPR 9N region, the resulting software tools and infrastructure should be helpful in establishing similar systems for other sections of the global mid-ocean ridge. Work in progress includes efforts to develop: (1) virtual database to incorporate diverse data types with domain-specific metadata into a global schema that allows web-query across different marine geology data sets, and an analogous declarative (database available) description of tools and models; (2) the ability to move data between GIS and the above DBMS, and tools to encourage data submission to archivesl (3) tools for finding and viewing archives, and translating between formats; (4) support for "computational steering" (tool composition

  13. Shape tracking with occlusions via coarse-to-fine region-based sobolev descent

    KAUST Repository

    Yang, Yanchao

    2015-05-01

    We present a method to track the shape of an object from video. The method uses a joint shape and appearance model of the object, which is propagated to match shape and radiance in subsequent frames, determining object shape. Self-occlusions and dis-occlusions of the object from camera and object motion pose difficulties to joint shape and appearance models in tracking. They are unable to adapt to new shape and appearance information, leading to inaccurate shape detection. In this work, we model self-occlusions and dis-occlusions in a joint shape and appearance tracking framework. Self-occlusions and the warp to propagate the model are coupled, thus we formulate a joint optimization problem. We derive a coarse-to-fine optimization method, advantageous in tracking, that initially perturbs the model by coarse perturbations before transitioning to finer-scale perturbations seamlessly. This coarse-to-fine behavior is automatically induced by gradient descent on a novel infinite-dimensional Riemannian manifold that we introduce. The manifold consists of planar parameterized regions, and the metric that we introduce is a novel Sobolev metric. Experiments on video exhibiting occlusions/dis-occlusions, complex radiance and background show that occlusion/dis-occlusion modeling leads to superior shape accuracy. © 2014 IEEE.

  14. Major Artery Occlusion: a Rare Complication of Sickle Cell Disease

    Directory of Open Access Journals (Sweden)

    Adnan Agha

    2010-02-01

    Full Text Available Abstract: Sickle cell disease is hereditary hemoglobinopathy which causes haemolytic anemia, vaso-occlusive crisis, ischemic injuries and many other morbidities like cerebral infarction.  In this report, we describe a case of a young patient with sickle cell disease presenting with right-sided weakness and slurring of speech with examination confirming right-sided hemiparesis with motor aphasia. On further investigation, she was found to have frontotemporal infarction.  On magnetic resonance imaging with angiography, she was found to have absent circulation in left internal carotid artery probably secondary to sickle cell disease.  Major vessel occlusion is rare complication of sickle cell disease that one must bear in mind.

  15. A mathematical model for cost of maritime transport. Application to competitiveness of nuclear vessels; Modele mathematique du cout de transport maritime application a la competitivite du navire nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Dorval, C. [Commissariat a l' Energie Atomique, 75 - Paris (France)

    1966-05-01

    In studying the competitiveness of a nuclear merchant vessel, economic assessments in terms of figures were discarded in favor of a simplified model, which gives a clearer idea of the mechanism of the comparison between alternative vessels and the particular influence of each parameter. An expression is formulated for the unit cost per ton carried over a given distance as a function of the variables (speed and deadweight tonnage) and is used to determine the optima for conventional and nuclear vessels. To represent the freight market involved in the optimization studies, and thus in the competitiveness computation, two cases are taken into account: the tonnage to be carried annually is limited, and the tonnage to be carried annually is not limited. In both cases the optima are calculated and compared for a conventional and a nuclear vessel. Competitiveness curves are plotted as a function of the ratios of nuclear and conventional fuel costs and nuclear and conventional marginal power costs. These curves express the limiting values of the above two ratios for which the transport costs of the nuclear and conventional vessels are equal. The competitiveness curves vary considerably according to the hypothesis adopted for the freight market and the limit of tonnage carried annually. (author) [French] Pour etudier la competitivite du navire marchand nucleaire, plutot que de nous livrer a des evaluations economiques chiffrees, discutables dans l'etat actuel des etudes, nous utilisons un modele simplifie permettant de mieux saisir le mecanisme de la comparaison des navires et l'influence particuliere de chaque parametre. Nous etablissons une expression du cout unitaire de la tonne transportee sur un parcours donne en fonction des variables vitesse et port en lourd. Et nous l'utilisons pour determiner les optima des navires classiques et nucleaires. Pour representer le marche du fret qui intervient dans les etudes d'optimisation, et donc dans la

  16. Occlusion-Aware View Interpolation

    Directory of Open Access Journals (Sweden)

    Janusz Konrad

    2009-01-01

    Full Text Available View interpolation is an essential step in content preparation for multiview 3D displays, free-viewpoint video, and multiview image/video compression. It is performed by establishing a correspondence among views, followed by interpolation using the corresponding intensities. However, occlusions pose a significant challenge, especially if few input images are available. In this paper, we identify challenges related to disparity estimation and view interpolation in presence of occlusions. We then propose an occlusion-aware intermediate view interpolation algorithm that uses four input images to handle the disappearing areas. The algorithm consists of three steps. First, all pixels in view to be computed are classified in terms of their visibility in the input images. Then, disparity for each pixel is estimated from different image pairs depending on the computed visibility map. Finally, luminance/color of each pixel is adaptively interpolated from an image pair selected by its visibility label. Extensive experimental results show striking improvements in interpolated image quality over occlusion-unaware interpolation from two images and very significant gains over occlusion-aware spline-based reconstruction from four images, both on synthetic and real images. Although improvements are obvious only in the vicinity of object boundaries, this should be useful in high-quality 3D applications, such as digital 3D cinema and ultra-high resolution multiview autostereoscopic displays, where distortions at depth discontinuities are highly objectionable, especially if they vary with viewpoint change.

  17. Occlusion-Aware View Interpolation

    Directory of Open Access Journals (Sweden)

    Ince Serdar

    2008-01-01

    Full Text Available Abstract View interpolation is an essential step in content preparation for multiview 3D displays, free-viewpoint video, and multiview image/video compression. It is performed by establishing a correspondence among views, followed by interpolation using the corresponding intensities. However, occlusions pose a significant challenge, especially if few input images are available. In this paper, we identify challenges related to disparity estimation and view interpolation in presence of occlusions. We then propose an occlusion-aware intermediate view interpolation algorithm that uses four input images to handle the disappearing areas. The algorithm consists of three steps. First, all pixels in view to be computed are classified in terms of their visibility in the input images. Then, disparity for each pixel is estimated from different image pairs depending on the computed visibility map. Finally, luminance/color of each pixel is adaptively interpolated from an image pair selected by its visibility label. Extensive experimental results show striking improvements in interpolated image quality over occlusion-unaware interpolation from two images and very significant gains over occlusion-aware spline-based reconstruction from four images, both on synthetic and real images. Although improvements are obvious only in the vicinity of object boundaries, this should be useful in high-quality 3D applications, such as digital 3D cinema and ultra-high resolution multiview autostereoscopic displays, where distortions at depth discontinuities are highly objectionable, especially if they vary with viewpoint change.

  18. 2D Fast Vessel Visualization Using a Vessel Wall Mask Guiding Fine Vessel Detection

    Directory of Open Access Journals (Sweden)

    Sotirios Raptis

    2010-01-01

    and then try to approach the ridges and branches of the vasculature's using fine detection. Fine vessel screening looks into local structural inconsistencies in vessels properties, into noise, or into not expected intensity variations observed inside pre-known vessel-body areas. The vessels are first modelled sufficiently but not precisely by their walls with a tubular model-structure that is the result of an initial segmentation. This provides a chart of likely Vessel Wall Pixels (VWPs yielding a form of a likelihood vessel map mainly based on gradient filter's intensity and spatial arrangement parameters (e.g., linear consistency. Specific vessel parameters (centerline, width, location, fall-away rate, main orientation are post-computed by convolving the image with a set of pre-tuned spatial filters called Matched Filters (MFs. These are easily computed as Gaussian-like 2D forms that use a limited range sub-optimal parameters adjusted to the dominant vessel characteristics obtained by Spatial Grey Level Difference statistics limiting the range of search into vessel widths of 16, 32, and 64 pixels. Sparse pixels are effectively eliminated by applying a limited range Hough Transform (HT or region growing. Major benefits are limiting the range of parameters, reducing the search-space for post-convolution to only masked regions, representing almost 2% of the 2D volume, good speed versus accuracy/time trade-off. Results show the potentials of our approach in terms of time for detection ROC analysis and accuracy of vessel pixel (VP detection.

  19. Modeling the fate of p,p'-DDT in water and sediment of two typical estuarine bays in South China: Importance of fishing vessels' inputs.

    Science.gov (United States)

    Fang, Shu-Ming; Zhang, Xianming; Bao, Lian-Jun; Zeng, Eddy Y

    2016-05-01

    Antifouling paint applied to fishing vessels is the primary source of dichloro-diphenyl-trichloroethane (DDT) to the coastal marine environments of China. With the aim to provide science-based support of potential regulations on DDT use in antifouling paint, we utilized a fugacity-based model to evaluate the fate and impact of p,p'-DDT, the dominant component of DDT mixture, in Daya Bay and Hailing Bay, two typical estuarine bays in South China. The emissions of p,p'-DDT from fishing vessels to the aquatic environments of Hailing Bay and Daya Bay were estimated as 9.3 and 7.7 kg yr(-1), respectively. Uncertainty analysis indicated that the temporal variability of p,p'-DDT was well described by the model if fishing vessels were considered as the only direct source, i.e., fishing vessels should be the dominant source of p,p'-DDT in coastal bay areas of China. Estimated hazard quotients indicated that sediment in Hailing Bay posed high risk to the aquatic system, and it would take at least 21 years to reduce the hazards to a safe level. Moreover, p,p'-DDT tends to migrate from water to sediment in the entire Hailing Bay and Daya Bay. On the other hand, our previous research indicated that p,p'-DDT was more likely to migrate from sediment to water in the maricultured zones located in shallow waters of these two bays, where fishing vessels frequently remain. These findings suggest that relocating mariculture zones to deeper waters would reduce the likelihood of farmed fish contamination by p,p'-DDT. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Mix Model of FE Method and IPSO Algorithm for Dome Shape Optimization of Articulated Pressure Vessels Considering the Effect of Non-geodesic Trajectories

    Science.gov (United States)

    Paknahad, A.; Nourani, R.

    2014-04-01

    The main essential topic for the design of articulated pressure vessels is related to the determination of the optimal meridian profile. This article, aimed to present the new model for optimum design of dome contours for filament wound articulated pressure vessels based on non-geodesic trajectories. The current model is a mix of finite element analysis and inertia weight particle swarm optimization algorithm. Geometrical limitations, stability-ensuring winding conditions and the Tsai-Wu failure criterion have been used as optimization constraints. Classical lamination theory and non-geodesic trajectories are used to analyse the field stress equations and increase the structural performance. The geometry of dome contours is defined by the B-spline curves with twenty-one points. The results, when compared to the previously published results, indicate the efficiency of the presented model in achieving superior performance of dome shape for articulated pressure vessels. Also, it is shown that the design based on non-geodesic trajectories using this model gains better response than the design by geodesics type.

  1. Simultaneous assessment of vessel size index, relative blood volume, and vessel permeability in a mouse brain tumor model using a combined spin echo gradient echo echo-planar imaging sequence and viable tumor analysis.

    Science.gov (United States)

    Kording, Fabian; Weidensteiner, Claudia; Zwick, Stefan; Osterberg, Nadja; Weyerbrock, Astrid; Staszewski, Ori; von Elverfeldt, Dominik; Reichardt, Wilfried

    2014-12-01

    Combining multiple imaging biomarkers in one magnetic resonance imaging (MRI) session would be beneficial to gain more data pertaining to tumor vasculature under therapy. Therefore, simultaneous measurement of perfusion, permeability, and vessel size imaging (VSI) using a gradient echo spin echo (GE-SE) sequence with injection of a clinically approved gadolinium (Gd)-based contrast agent was assessed in an orthotopic glioma model. A combined spin echo gradient echo echo-planar imaging sequence was implemented using a single contrast agent Gd diethylenetriaminepentaacetic acid (Gd-DTPA). This sequence was tested in a mouse brain tumor model (U87_MG), also under treatment with an antiangiogenic agent (bevacizumab). T2 maps and the apparent diffusion coefficient (ADC) were used to differentiate regions of cell death and viable tumor tissue. In viable tumor tissue regional blood volume was 5.7 ± 0.6% in controls and 5.2 ± 0.3% in treated mice. Vessel size was 18.1 ± 2.4 μm in controls and 12.8 ± 2.0 μm in treated mice, which correlated with results from immunohistochemistry. Permeability (K(trans) ) was close to zero in treated viable tumor tissue and 0.062 ± 0.024 min(-1) in controls. Our MRI method allows simultaneous assessment of several physiological and morphological parameters and extraction of MRI biomarkers for vasculature. These could be used for treatment monitoring of novel therapeutic agents such as antiangiogenic drugs. © 2014 Wiley Periodicals, Inc.

  2. Cell culture for three-dimensional modeling in rotating-wall vessels: an application of simulated microgravity

    Science.gov (United States)

    Schwarz, R. P.; Goodwin, T. J.; Wolf, D. A.

    1992-01-01

    High-density, three-dimensional cell cultures are difficult to grow in vitro. The rotating-wall vessel (RWV) described here has cultured BHK-21 cells to a density of 1.1 X 10(7) cells/ml. Cells on microcarriers were observed to grow with enhanced bridging in this batch culture system. The RWV is a horizontally rotated tissue culture vessel with silicon membrane oxygenation. This design results in a low-turbulence, low-shear cell culture environment with abundant oxygenation. The RWV has the potential to culture a wide variety of normal and neoplastic cells.

  3. Development Of An Atherothrombotic Occlusion In The Rabbit Carotid Artery: Accessed By New Computerized B- Mode Ultrasound Image Processing Technology And Histopathology

    Directory of Open Access Journals (Sweden)

    Hossein Mehrad

    2017-02-01

    Full Text Available Introduction: Thrombus formation on a disrupted atherosclerotic soft plaque is a key event that leads to atherothrombosis. Atherothrombosis is one of the leading causes of acute coronary syndrome and ischemic stroke. Our ability to test new protocols for the treatment of atherothrombotic stenosis in humans is limited for obvious ethical reasons; therefore, a precise understanding of the mechanism of atherothrombotic occlusion in human carotid artery, which give rise to thrombosis, emboli and stroke, requires a suitable animal model that would mimic the same characteristics well. Aims: The aim of this study was to generate an easily reproducible and inexpensive experimental rabbit carotid model of atherothrombotic occlusion with morphological similarities to the human disease and the subsequent assessment of the reliability of new computerized B- mode ultrasound image processing technology in the study of lumen area stenosis in this model. Methods: Briefly, male New Zealand white rabbits were submitted to common carotid artery atherothrombotic occlusion by primary balloon injury followed 1.5% cholesterol- rich diet injury for eight weeks and finally perivascularly severe cold injury. All of the rabbits' arteries were imaged by B-mode ultrasound weekly, after which the rabbits were sacrificed, and their vessels were processed for histopathology. Ultrasound longitudinal view images from three cardiac cycles were processed by a new computerized analyzing method based on dynamic programming and maximum gradient algorithm for measurement of instantaneous changes in arterial wall thickness and lumen diameter in sequential ultrasound images. Results: Histopathology results showed progressive changes, from the lipid-laden cells and fibrous connective tissue proliferation, fibrolipid plaque formation, resulting in vessel wall thickening, remodeling, neovascularization and lumen narrowing (before perivascularly severe cold injury using liquid nitrogen up

  4. Successful treatment of acquired uterine arterial venous malformation using N-butyl-2-cyanoacrylate under balloon occlusion.

    Science.gov (United States)

    Woodhams, Reiko; Ogasawara, Go; Ishida, Kenichiro; Fujii, Kaoru; Yamane, Takuro; Nishimaki, Hiroshi; Matsunaga, Keiji; Inoue, Yusuke

    2014-09-01

    We present two cases of acquired uterine arterial venous malformation (AVM) which was diagnosed because of massive genital bleeding successfully treated with transcatheter arterial embolization (TAE), using N-butyl-2-cyanoacrylate (NBCA) under balloon occlusion. Balloon occlusion at the uterine artery was performed in both patients for diffuse distribution of NBCA in multiple feeding branches, as well as to the pseudoaneurysm, and for the prevention of NBCA reflux. In one of our patients, balloon occlusion of the draining vein was simultaneously performed to prevent NBCA migration through accompanying high-flow arteriovenous fistula (AVF). Doppler ultrasound at 6 months of both patients documented persistent complete occlusion of AVM. Complete and safe obliteration of acquired uterine AVM was accomplished using NBCA as embolic agent, under balloon occlusion at the communicating vessels of acquired uterine AVM.

  5. Drug and light dose responses to focal photodynamic therapy of single blood vessels in vivo

    Science.gov (United States)

    Khurana, Mamta; Moriyama, Eduardo H.; Mariampillai, Adrian; Samkoe, Kimberley; Cramb, David; Wilson, Brian C.

    2009-11-01

    As part of an ongoing program to develop two-photon (2-γ) photodynamic therapy (PDT) for treatment of wet-form age-related macular degeneration (AMD) and other vascular pathologies, we have evaluated the reciprocity of drug-light doses in focal-PDT. We targeted individual arteries in a murine window chamber model, using primarily the clinical photosensitizer Visudyne/liposomal-verteporfin. Shortly after administration of the photosensitizer, a small region including an arteriole was selected and irradiated with varying light doses. Targeted and nearby vessels were observed for a maximum of 17 to 25 h to assess vascular shutdown, tapering, and dye leakage/occlusion. For a given end-point metric, there was reciprocity between the drug and light doses, i.e., the response correlated with the drug-light product (DLP). These results provide the first quantification of photosensitizer and light dose relationships for localized irradiation of a single blood vessel and are compared to the DLP required for vessel closure between 1-γ and 2-γ activation, between focal and broad-beam irradiation, and between verteporfin and a porphyrin dimer with high 2-γ cross section. Demonstration of reciprocity over a wide range of DLP is important for further development of focal PDT treatments, such as the targeting of feeder vessels in 2-γ PDT of AMD.

  6. Use of a Dacron shape-memory intravascular coil to achieve slow, progressive occlusion of the jugular vein in dogs.

    Science.gov (United States)

    Nanfelt, Michelle R; Marolf, Angela J; Powers, Barbara E; Monnet, Eric

    2011-10-01

    To investigate the ability of shape memory Dacron polymer vascular coils to induce the complete, gradual occlusion of the canine jugular vein. Observational pilot study. Nine purpose-bred dogs. Eighteen coils were deployed in nine dogs using fluoroscopic-guided percutaneous transvenous coil implantation. Individual coil formulations varied around a Dacron polymer base. Jugular vein diameter, percent vessel occlusion, and thrombus echogenicity were monitored at weekly intervals using ultrasonography. Affected jugular veins were harvested at 6 weeks post-implantation and histopathological analysis was performed to assess adventitial fibrosis, intimal layer thickening, and inflammation. Ten coils migrated from the jugular veins to the pulmonary vasculature within 0-2 weeks following implantation. Three jugular veins achieved at least 90% occlusion at six weeks. Histopathology of these jugular veins revealed marked perivascular thickening and fibrovascular proliferation, increased infiltration of macrophages, neutrophils and lymphocytes, and abundant fibroplasia. Complete, gradual occlusion of a jugular vein was achieved in three dogs. Significant vessel wall reaction and inflammation can induce gradual vessel occlusion when a Dacron coil remains implanted within the jugular vein. Dacron polymer coils could be a feasible treatment option for the gradual occlusion of congenital portosystemic shunts in dogs using minimally invasive, percutaneous transvenous implantation. © Copyright 2011 by The American College of Veterinary Surgeons.

  7. Occlusion Issues in Early Renaissance Art

    National Research Council Canada - National Science Library

    Gillam, Barbara

    2011-01-01

    .... Much has been written about perspective in art but little about occlusion. Here I examine some of the strategies for depicting occlusion used by early Renaissance painters in relation to ecological considerations and perceptual research...

  8. Occlusal factors are not related to self-reported bruxism.

    Science.gov (United States)

    Manfredini, Daniele; Visscher, Corine M; Guarda-Nardini, Luca; Lobbezoo, Frank

    2012-01-01

    To estimate the contribution of various occlusal features of the natural dentition that may identify self-reported bruxers compared to nonbruxers. Two age- and sex-matched groups of self-reported bruxers (n = 67) and self-reported nonbruxers (n = 75) took part in the study. For each patient, the following occlusal features were clinically assessed: retruded contact position (RCP) to intercuspal contact position (ICP) slide length ( 4 mm, a deep bite), horizontal overlap (> 4 mm was considered a large horizontal overlap), incisor dental midline discrepancy (bruxism (dependent variable). Accuracy values to predict self-reported bruxism were unacceptable for all occlusal variables. The only variable remaining in the final regression model was laterotrusive interferences (P = .030). The percentage of explained variance for bruxism by the final multiple regression model was 4.6%. This model including only one occlusal factor showed low positive (58.1%) and negative predictive values (59.7%), thus showing a poor accuracy to predict the presence of self-reported bruxism (59.2%). This investigation suggested that the contribution of occlusion to the differentiation between bruxers and nonbruxers is negligible. This finding supports theories that advocate a much diminished role for peripheral anatomical-structural factors in the pathogenesis of bruxism.

  9. Dental occlusion and temporomandibular disorders.

    Science.gov (United States)

    Stone, J Caitlin; Hannah, Andrew; Nagar, Nathan

    2017-10-27

    Data sourcesMedline, Scopus and Google Scholar.Study selectionTwo reviewers selected studies independently. English language clinical studies assessing the association between temporomandibular disorders (TMD) and features of dental occlusion were considered.Data extraction and synthesisStudy quality was assessed based on the Newcastle-Ottawa Scale (NOS) and a narrative synthesis was presented.ResultsIn all 25 studies (17 case-control, eight comparative) were included. Overall there was a high variability between occlusal features and TMD diagnosis. Findings were consistent with a lack of clinically relevant association between TMD and dental occlusion. Only two studies were associated with TMD in the majority (≥50%) of single variable analyses in patient populations. Only mediotrusive interferences are associated with TMD in the majority of multiple variable analyses.ConclusionsThe findings support the absence of a disease-specific association, there is no ground to hypothesise a major role for dental occlusion in the pathophysiology of TMDs. Dental clinicians are thus encouraged to move forward and abandon the old-fashioned gnathological paradig.

  10. Pig specific vascular anatomy allows acute infrarenal aortic occlusion without hind limb ischemia and stepwise occlusion without clinical signs.

    Science.gov (United States)

    Haacke, N; Unger, J K; Haidenhein, C; Russ, M; Hiebl, B; Niehues, S M

    2011-01-01

    In a porcine, aortic graft model we found 5 animals to develop and survive unnoticed, complete infrarenal aortic occlusion and 2 pigs with an acute occlusion but rather unspecific clinical symptoms. We investigated the pigs' vascular system to classify the anatomic capabilities to compensate for an acute abdominal aortic occlusion. Retrospective analysis of CT scans and clinical data to specify unexpected results in a case series of infrarenal occlusion in a porcine model. Collaborative study of experimental and clinical departments. Fifteen healthy female minipigs. All pigs underwent an infrarenal aortic graft intervention. Anesthesia and perioperative management of the animals were preformed along the standard operating procedures of the local Department of Experimental Medicine. All animals received perioperative antibiotics, ASS, and carprofen for postoperative analgesia. Arterial pressure, heart rate, body temperature, and diuresis were monitored during surgery and therapeutic interventions. Contrast media based computed tomography (CT) with total body scans were performed at 1, 4, 10, 12 weeks after surgery. Comparable scans of cardiovascular healthy subjects (humans and pigs) and patients with a Leriche's syndrome were analyzed. Neither acute (within the first 12 h after surgery) nor stepwise total aortic occlusion show unmistakable clinical signs. In pigs, the epigastric artery (EGA) - which is in connection with suprarenal lumbal arteries, subclavian and external iliac artery - is highly developed associated to the high number of mammary glands of about 7 on one side. In humans, the ratio of aortic to EGA-diameter is 1 : 0.15. In minipigs we found a ratio of 1 : 0.43 which changed during aortic occlusion resulting in a ratio of 1 : 0.58. Pigs with a slowly developing occlusion demonstrated an enlargement of the ureteric artery of about 210% completing a sufficient collateral system. While in the human Leriche's syndrome months are needed to enlarge the

  11. Patency of heart blood vessels under photosensitization reaction shortly after intravenous injection of talaporfin sodium in canine model

    Science.gov (United States)

    Hamada, Risa; Matsuzaki, Ryota; Ogawa, Emiyu; Arai, Tsunenori

    2016-03-01

    In order to investigate patency of heart blood vessels by photosensitization reaction shortly after intravenous injection of talaporfin sodium, we performed in vitro endothelial cell lethality study and in vivo study of heart blood vessel patency in canine one week after photosensitization reaction. Cell lethality of human umbilical vein endothelial cells under different albumin concentrations corresponding with blood and interstice concentrations were employed and their lethality 2 hours after the reaction was measured by WST assay in vitro. Almost all cells survived by 40 J/cm2 photosensitization reaction with blood albumin concentration. Laser diffuser made of plastic optical fiber with 70 mm in length was used in vivo. Red diode laser of 664nm wavelength was emitted from this diffuser with 17.1-42.9 mW/cm in 10 minutes. We estimated the fluence rate distribution by a ray-trace simulator using pre-measured optical coefficients of myocardium tissue, μa 0.12 mm-1 and μs' 0.36 mm-1. Almost all blood vessels were patent in every irradiation conditions in canine heart. Coronary artery and vein up to 1 mm diameter were patent in typical myocardium sample with 25.7 mW/cm. We estimated fluence rate distribution of this sample and found that blood vessels were patent even fluence rate over 40 J/cm2. This in vivo study could be explained by the result of in vitro study. We suggest that this blood vessel patency after our particular photosensitization reaction might be because of few photosensitizer uptake in the blood endothelial cells and/or reduced oxidation damage by thick albumin concentration in blood.

  12. A controversy with respect to occlusion

    OpenAIRE

    Fukushima, Shunji

    2016-01-01

    Summary There are very little controversies on occlusion in healthy individuals, where centric relation is regarded as the criterion for assessing the present occlusion and also for establishing a new occlusal relationship between the upper and the lower jaws. On the other hand, the occlusal position in patients with deformed condyles still remains to be clarified. In this review, the effectiveness and limits of centric relation in these patients are discussed. In addition, the muscle induced...

  13. Clinical issues in occlusion – Part II

    OpenAIRE

    Patel, Mahul; Alani, Aws

    2015-01-01

    Occlusal diagnosis plays an important role in the planning and subsequent delivery of predictable functional and aesthetic restorations and prostheses. Once an occlusal problem is identified there are a number of techniques and materials that can be utilised to record occlusal relationships, subsequently analyse them and incorporate information obtained into the delivery of tooth restoration or replacement. This paper discusses the clinical and technical aspects of occlusal examination and an...

  14. Malignant occlusion of the coeliac axis

    Energy Technology Data Exchange (ETDEWEB)

    Jonsson, K.; Wattsgaard, C.; Genell, S. (Malmoe Allmaenna Sjukhus, Malmoe (Sweden). Dept. of Diagnostic Radiology)

    1982-01-01

    Occlusion or extensive stenosis of the coeliac trunk due to malignant tumor are described in three patients. If, at angiography of a patient with a malignant tumor, occlusion of the coeliac trunk is found, tumor or lymph node metastases causing the occlusion must be considered; this may be of importance when intra-arterial chemotherapy of the tumor is planned.

  15. New approaches to dental occlusion: a literature update.

    Science.gov (United States)

    Franco, Ana Lúcia; de Andrade, Marcelo Ferrarezi; Segalla, José Claudio Martins; Gonçalves, Daniela Aparecida de Godoi; Camparis, Cinara Maria

    2012-04-01

    Because the study of occlusion is a basic area in dentistry, its components, physiology and integration with the stomatognathic system (SS) have been the subject of interest in the scientific literature. However, the focus given to this issue has changed substantially. Currently, new approaches have been proposed in order to update concepts and to demonstrate the full integration and functionality of this system within the human body. With this approach, the authors proposed the following literature review aimed at gathering recent papers (published from 2000 to 2010) with innovative study design, methodology and/or results. The authors' intention is to show the main trends in the study of occlusion and the SS. The literature review was conducted in the PubMed database, using initially the term "dental occlusion" as a key-word. As items of interest were found, papers were grouped by categories according to their main subject matter. Forty-seven articles were selected and the main categories obtained were: 1. functional magnetic resonance imaging (fMRI); 2. brain activation; 3. masticatory/occlusal function; 4. body function and physical performance; 5. osseoperception; 6. finite element models; and 7. occlusion and pain. Observing the current literature, the authors found that recent studies present different methodologies for the study of occlusion. These studies have allowed scientists to obtain detailed information about the physiology of occlusion and the SS, as well as about its integration in the body. Research in this area should be continued in order to clarify, in detail, the role of each component of the SS and its interaction with human physiology.

  16. A surgical model of permanent and transient middle cerebral artery stroke in the sheep.

    Directory of Open Access Journals (Sweden)

    Adam J Wells

    Full Text Available BACKGROUND: Animal models are essential to study the pathophysiological changes associated with focal occlusive stroke and to investigate novel therapies. Currently used rodent models have yielded little clinical success, however large animal models may provide a more suitable alternative to improve clinical translation. We sought to develop a model of acute proximal middle cerebral artery (MCA ischemic stroke in sheep, including both permanent occlusion and transient occlusion with reperfusion. MATERIALS AND METHODS: 18 adult male and female Merino sheep were randomly allocated to one of three groups (n = 6/gp: 1 sham surgery; 2 permanent proximal MCA occlusion (MCAO; or 3 temporary MCAO with aneurysm clip. All animals had invasive arterial blood pressure, intracranial pressure and brain tissue oxygen monitoring. At 4 h following vessel occlusion or sham surgery animals were killed by perfusion fixation. Brains were processed for histopathological examination and infarct area determination. 6 further animals were randomized to either permanent (n = 3 or temporary MCAO (n = 3 and then had magnetic resonance imaging (MRI at 4 h after MCAO. RESULTS: Evidence of ischemic injury in an MCA distribution was seen in all stroke animals. The ischemic lesion area was significantly larger after permanent (28.8% compared with temporary MCAO (14.6%. Sham animals demonstrated no evidence of ischemic injury. There was a significant reduction in brain tissue oxygen partial pressure after permanent vessel occlusion between 30 and 210 mins after MCAO. MRI at 4 h demonstrated complete proximal MCA occlusion in the permanent MCAO animals with a diffusion deficit involving the whole right MCA territory, whereas temporary MCAO animals demonstrated MRA evidence of flow within the right MCA and smaller predominantly cortical diffusion deficits. CONCLUSIONS: Proximal MCAO can be achieved in an ovine model of stroke via a surgical approach. Permanent

  17. BIOASSAY VESSEL FAILURE ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Vormelker, P

    2008-09-22

    Two high-pressure bioassay vessels failed at the Savannah River Site during a microwave heating process for biosample testing. Improper installation of the thermal shield in the first failure caused the vessel to burst during microwave heating. The second vessel failure is attributed to overpressurization during a test run. Vessel failure appeared to initiate in the mold parting line, the thinnest cross-section of the octagonal vessel. No material flaws were found in the vessel that would impair its structural performance. Content weight should be minimized to reduce operating temperature and pressure. Outer vessel life is dependent on actual temperature exposure. Since thermal aging of the vessels can be detrimental to their performance, it was recommended that the vessels be used for a limited number of cycles to be determined by additional testing.

  18. Obstructive coronary artery disease: reverse attenuation gradient sign at CT indicates distal retrograde flow--a useful sign for differentiating chronic total occlusion from subtotal occlusion.

    Science.gov (United States)

    Li, Minghua; Zhang, Jiayin; Pan, Jingwei; Lu, Zhigang

    2013-03-01

    To study the clinical importance of the reverse attenuation gradient (RAG) sign in patients with occlusive coronary artery disease observed with coronary computed tomographic (CT) angiography. All patients provided written informed consent, and the institutional review board committee approved the study protocol. Eighty consecutive patients (mean age, 67.1 years ± 12.1 [standard deviation]; range, 35-87 years; 62 men [mean age, 65.8 years ± 12.5; range, 35-86 years] and 18 women [mean age, 71.7 years ± 9.3; range, 58-87 years]) were enrolled prospectively in this study. The RAG sign was defined as the reverse intraluminal opacification gradient of vessels distal to the occlusive lesions, which has lower attenuation in the proximal segment and gradually increased attenuation along the vessel. Other parameters, such as lesion length and bridging collateral vessels visible at coronary CT angiography, were recorded. Mann-Whitney Wilcoxon and Fisher exact tests were used for comparison. There were 94 occlusive lesions. Invasive coronary angiography was used to confirm 49 chronic total occlusions (CTOs) and 45 subtotal occlusions (SOs). The CTO group had the RAG sign significantly more frequently than did the SO group (65% [32 of 49] vs 7% [three of 45]; P attenuation gradient (5.1 HU/10 mm ± 13.4 vs -13.4 HU/10 mm ± 8.7; P < .001) and lesion length (23.6 mm ± 22.7 vs 6 mm ± 3; P < .001) was noted between the groups. Bridging collateral vessels were present in only four cases of CTO at coronary CT angiography. All segments with RAG at coronary CT angiography were shown by means of invasive coronary angiography to be supplied by retrograde collateral vessels. When a combination of all those parameters was used for diagnosis of CTO, sensitivity and specificity were 90% (44 of 49) and 93% (42 of 45), respectively. The RAG sign represents the retrograde collateral flow distal to an occlusive lesion. This sign is highly specific for CTO and helps to differentiate CTO

  19. Finite element analysis to estimate burst pressure of mild steel pressure vessel using Ramberg–Osgood model

    OpenAIRE

    Deolia, Puneet; Firoz A. Shaikh

    2016-01-01

    Burst pressure is the pressure at which vessel burst/crack and internal fluid leaks. An accurate prediction of burst pressure is necessary in chemical, medical and aviation industry. Burst pressure is a design safety limit, which should not be exceeded. If this pressure is exceeded it may lead to the mechanical breach and permanent loss of pressure containment. So burst pressure calculation is necessary for all the critical applications. To numerically calculate burst pressure material curve ...

  20. Occlusion for fixed prosthodontics: a historical perspective of the gnathological influence.

    Science.gov (United States)

    Pokorny, Paul H; Wiens, Jonathan P; Litvak, Harold

    2008-04-01

    This article addresses the historical perspective of the gnathological influence upon the concepts of occlusion for fixed prosthodontics. A critical assessment and subsequent scientific validation of occlusal theories require an understanding of their evolution in the formative years and the subsequent development of effective models for clinical practice. While gnathological concepts offer a structured methodology for prosthodontic procedures, further research is needed to corroborate current occlusal treatment approaches. This review focuses on the "classic" fixed prosthodontic literature and the currently available scientific literature involving fixed prosthodontic dentate occlusion and gnathology. A MEDLINE search was performed to identify English-language peer-reviewed publications spanning the last 56 years, along with an extensive hand search for years prior. Electronic searches of the literature were performed in MEDLINE using the key words: case series, clinical trials, cohort studies, fixed partial denture occlusion, dental occlusion, dental occlusion research, centric relation, incisal guidance, maximal intercuspation, occlusal vertical dimension, and occlusion, in various combinations to obtain potential references for review. A total of 10,382 English-language nonduplicate titles were obtained for 1950-2006 for the key words "dental occlusion." Other key word searches produced smaller numbers of articles, many of which were duplicates due to multiple searches and were subsequently eliminated. Manual hand searching of the MEDLINE reference list and other journals of interest was performed to identify any articles missed in the original search. Articles were included for review if they contained emerging occlusal theories, new technologies, or occlusal studies that included multiple subjects in contrast to case reports.

  1. Vertex occlusal radiography in localizing unerupted mesiodentes

    Directory of Open Access Journals (Sweden)

    P Chalakkal

    2011-01-01

    Full Text Available The aim was to compare the vertex occlusal projection with the anterior maxillary occlusal projection in localizing the position of mesiodentes. Mesiodentes were observed in an 8-year-old boy with an anterior maxillary occlusal radiograph. A vertex occlusal radiograph was taken to compare it with the former in terms of mesiodentes localization with respect to the maxillary central incisors. The vertex occlusal radiograph provided greater details of the position and proximity of mesiodentes with respect to the long axis of maxillary central incisors in comparison to the anterior maxillary occlusal radiograph. Vertex occlusal radiography is an important diagnostic tool in diagnosing the presence, position, and proximity of mesiodentes with respect to the long axis of normally aligned maxillary central incisors. However, it is not recommended for routine use in a patient as its radiation dose is higher than conventional intraoral radiographic methods.

  2. Clinical issues in occlusion - Part II.

    Science.gov (United States)

    Patel, Mahul; Alani, Aws

    2015-12-01

    Occlusal diagnosis plays an important role in the planning and subsequent delivery of predictable functional and aesthetic restorations and prostheses. Once an occlusal problem is identified there are a number of techniques and materials that can be utilised to record occlusal relationships, subsequently analyse them and incorporate information obtained into the delivery of tooth restoration or replacement. This paper discusses the clinical and technical aspects of occlusal examination and analysis outlining contemporary and traditional techniques in their utilisation. Aspects of occlusal examination will be revisited; the identification and recording of centric occlusion as well as subsequent articulation will be discussed. The requirement for occlusal splint provision will also be discussed and illustrated. Copyright © 2015. Published by Elsevier B.V.

  3. Expression of the growth factor progranulin in endothelial cells influences growth and development of blood vessels: a novel mouse model.

    Science.gov (United States)

    Toh, Huishi; Cao, Mingju; Daniels, Eugene; Bateman, Andrew

    2013-01-01

    Progranulin is a secreted glycoprotein that regulates cell proliferation, migration and survival. It has roles in development, tumorigenesis, wound healing, neurodegeneration and inflammation. Endothelia in tumors, wounds and placenta express elevated levels of progranulin. In culture, progranulin activates endothelial proliferation and migration. This suggested that progranulin might regulate angiogenesis. It was, however, unclear how elevated endothelial progranulin levels influence vascular growth in vivo. To address this issue, we generated mice with progranulin expression targeted specifically to developing endothelial cells using a Tie2-promoter/enhancer construct. Three Tie2-Grn mouse lines were generated with varying Tie2-Grn copy number, and were called GrnLo, GrnMid, and GrnHi. All three lines showed increased mortality that correlates with Tie2-Grn copy number, with greatest mortality and lowest germline transmission in the GrnHi line. Death of the transgenic animals occurred around birth, and continued for three days after birth. Those that survived beyond day 3 survived into adulthood. Transgenic neonates that died showed vascular abnormalities of varying severity. Some exhibited bleeding into body cavities such as the pericardial space. Smaller localized hemorrhages were seen in many organs. Blood vessels were often dilated and thin-walled. To establish the development of these abnormalities, we examined mice at early (E10.5-14.5) and later (E15.5-17.5) developmental phases. Early events during vasculogenesis appear unaffected by Tie2-Grn as apparently normal primary vasculature had been established at E10.5. The earliest onset of vascular abnormality was at E15.5, with focal cerebral hemorrhage and enlarged vessels in various organs. Aberrant Tie2-Grn positive vessels showed thinning of the basement membrane and reduced investiture with mural cells. We conclude that progranulin promotes exaggerated vessel growth in vivo, with subsequent effects in

  4. Occlusal Classification in Relation to Original Cleft Width in Patients With Unilateral Cleft Lip and Palate.

    Science.gov (United States)

    Huang, Andrew H; Patel, Kamlesh B; Maschhoff, Clayton W; Huebener, Donald V; Skolnick, Gary B; Naidoo, Sybill D; Woo, Albert S

    2015-09-01

    To determine a correlation between the width of the cleft palate measured at the time of lip adhesion, definitive lip repair, and palatoplasty and the subsequent occlusal classification of patients born with unilateral cleft lip and palate. Retrospective, observational study. Referral, urban, children's hospital Participants : Dental models and records of 270 patients were analyzed. None. Angle occlusion classification. The mean age at which occlusal classification was determined was 11 ± 0.3 years. Of the children studies, 84 were diagnosed with Class I or II occlusion, 67 were diagnosed with Class III occlusion, and 119 were lost to follow up or transferred care. Mean cleft widths were significantly larger in subjects with Class III occlusion for all measures at time of lip adhesion and definitive lip repair (P < .02). At time of palatoplasty, cleft widths were significantly greater at the alveolus (P = .025) but not at the midportion of the hard palate (P = .35) or posterior hard palate (P = .10). Cleft widths from the lip through to the posterior hard palate are generally greater in children who are diagnosed with Class III occlusion later in life. Notably, the alveolar cleft width is significantly greater at each time point for patients who went on to develop Class III occlusion. There were no significant differences in cleft widths between patients diagnosed later with Class I and Class II occlusions.

  5. Blood Vessel Formation and Bone Regeneration Potential of the Stromal Vascular Fraction Seeded on a Calcium Phosphate Scaffold in the Human Maxillary Sinus Floor Elevation Model

    Directory of Open Access Journals (Sweden)

    Elisabet Farré-Guasch

    2018-01-01

    Full Text Available Bone substitutes are used as alternatives for autologous bone grafts in patients undergoing maxillary sinus floor elevation (MSFE for dental implant placement. However, bone substitutes lack osteoinductive and angiogenic potential. Addition of adipose stem cells (ASCs may stimulate osteogenesis and osteoinduction, as well as angiogenesis. We aimed to evaluate the vascularization in relation to bone formation potential of the ASC-containing stromal vascular fraction (SVF of adipose tissue, seeded on two types of calcium phosphate carriers, within the human MSFE model, in a phase I study. Autologous SVF was obtained from ten patients and seeded on β-tricalcium phosphate (n = 5 or biphasic calcium phosphate carriers (n = 5, and used for MSFE in a one-step surgical procedure. After six months, biopsies were obtained during dental implant placement, and the quantification of the number of blood vessels was performed using histomorphometric analysis and immunohistochemical stainings for blood vessel markers, i.e., CD34 and alpha-smooth muscle actin. Bone percentages seemed to correlate with blood vessel formation and were higher in study versus control biopsies in the cranial area, in particular in β-tricalcium phosphate-treated patients. This study shows the safety, feasibility, and efficiency of the use of ASCs in the human MSFE, and indicates a pro-angiogenic effect of SVF.

  6. Effect of prosthodontic planning on lateral occlusion scheme: a comparison between conventional and digital planning.

    Science.gov (United States)

    Abduo, Jaafar; Bennamoun, Mohammed; Tennant, Marc; McGeachie, John

    2015-01-01

    Recently, digital wax-up is proposed as a tool to aid prosthodontic planning. However, there are no data about the effect of prosthodontic planning on lateral occlusion scheme. This study aims to evaluate the impact of conventional and digital prosthodontic planning on lateral occlusion scheme. Dental models of 10 patients were collected. All models had Angle Class I occlusion and were undergoing prosthodontic treatment that would influence the lateral occlusion scheme. Each set of models had received both conventional wax-up and digital wax-up. In relation to the lateral occlusion scheme, the following variables were evaluated: the prevalence of the different lateral occlusion scheme, number of contacting teeth and percentage of each contacting tooth. Four excursive positions on the working side were included: 0.5, 1.0, 2.0 and 3.0 mm from the maximal intercuspation position. The lateral occlusion scheme of the two wax-up models was subjected to alterations following excursion. There was a tendency for the prevalence of canine-guided occlusion to increase and for the prevalence of group function occlusion to decrease with increasing excursion. The number of contacting teeth was decreasing with the increasing magnitude of excursion. For the 0.5 mm and 1.0 mm positions, the two wax-ups had significantly greater contacts than the pre-treatment models, while at the 2.0 mm and 3.0 mm positions, all the models were similar. For all models, canines were the most commonly contacting teeth, followed by the teeth adjacent to them. No difference was observed between the two wax-ups in relation to the number of contacting teeth. Although the prosthodontic planning had influenced the pattern of the lateral occlusion scheme and contacts, there was no difference between the conventional and digital prosthodontic planning.

  7. Assessment of mesenteric vascular steno-occlusive lesion in acute mesenteric ischemia: comparison between CT angiography and digital subtraction angiography

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Sang Soo; Jeong, Yong Yeon; Yoon, Woong; Lim, Hyo Soon; Song, Sang Gook; Jang Nam Kyu; Kim, Jae Kyu; Kang, Heoung Keun [Chonnam National University, Gwangju (Korea, Republic of); Shen, Yu Lan [YanBian Canner Hospital, Peijing (China)

    2005-09-15

    Acute mesenteric ischemia (AMI) is one of the most dramatic abdominal emergencies. The most common cause of AMI is a thrombo-embolism of the mesenteric artery or vein. The aim of this study was to evaluate the feasibility of CT angiography for evaluating mesenteric vascular steno-occlusive lesion in AMI. Fifteen patients with clinically and angiographically proven AMI underwent a two-phase CT. The CT angiographic images were reconstructed using a 3D rendering algorithm, such as the maximum intensity projection and volume-rendering. All the CT angiographic images were reviewed with respect to stenosis or occlusion of mesenteric vessel by the consensus of two radiologists, and were correlated with the findings of digital subtraction angiography. Digital subtraction angiography (DSA) visualized 60 mesenteric vessels including the superior mesenteric artery (n=15) and vein (n=15), and the inferior mesenteric artery (n=15) and vein (n=15). DSA showed steno-occlusive lesions in 16 mesenteric vessels (13 superior mesenteric arteries, two superior mesenteric vein, and one inferior mesenteric artery). CT angiography detected steno-occlusive lesions in 16 mesenteric vessels (12 superior mesenteric arteries, one superior mesenteric vein, and three inferior mesenteric arteries). The sensitivity, specificity, and accuracy of CT angiography for evaluating mesenteric vascular steno-occlusive lesion were 87.5%, 95.4%, and 93.3%, respectively. CT angiography is an useful adjunct to abdominal CT in an AMI setting on account of its ability to detect the causes of AMI such as a steno-occlusive lesion of the mesenteric vessel.

  8. Guam Abandoned Vessel Inventory

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA Abandoned Vessel Project Data for Guam. Abandoned vessels pose a significant threat to the NOAA Trust resources through physical destruction of coral habitats...

  9. Florida Abandoned Vessel Inventory

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA Abandoned Vessel Project Data for Florida. Abandoned vessels pose a significant threat to the NOAA Trust resources through physical destruction of coral...

  10. Vessel Arrival Info - Legacy

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Vessel Arrival Info is a spreadsheet that gets filled out during the initial stage of the debriefing process by the debriefer. It contains vessel name, trip...

  11. Occlusal status among Yemeni children

    Directory of Open Access Journals (Sweden)

    Nabil M Al-Zubair

    2014-01-01

    Full Text Available Objectives: The purpose of this study was to assess the occlusal status in schoolchildren in Yemen, and to compare the results with those of other studies. Materials and Methods: The sample for this epidemiological survey consisted of 3003 primary school students, half of whom were boys and the other half girls, aged 12 years. The subjects were randomly selected, and none had received previous orthodontic treatment. Variables examined included intra-arch irregularities and malalignment (crowding and spacing in the incisal segments of the arch and midline diastema and discrepancies in occlusal contact relationship (maxillary overjet, mandibular overjet, anterior openbite and antero-posterior molar relation. Results: The results showed that about 26.1% of the subjects were still in the late mixed dentition stage and 73.9% presented with a dentition in the early permanent stage. Normal overjet was found in 55% of the sample. Crowding was observed in 31.4% of the subjects and midline diastema in 14.2%. Conclusion: Occlusal status among Yemeni children was characterized by a relatively high frequency of dental crowding, as well as a relatively high frequency of anterior mandibular overjet (Class III malocclusions.

  12. Neuromuscular function in healthy occlusion.

    Science.gov (United States)

    Forrester, S E; Allen, S J; Presswood, R G; Toy, A C; Pain, M T G

    2010-09-01

    This study aimed to measure neuromuscular function for the masticatory muscles under a range of occlusal conditions in healthy, dentate adults. Forty-one subjects conducted maximum voluntary clenches under nine different occlusal loading conditions encompassing bilateral posterior teeth contacts with the mandible in different positions, anterior teeth contacts and unilateral posterior teeth contacts. Surface electromyography was recorded bilaterally from the anterior temporalis, superficial masseter, sternocleidomastoid, anterior digastric and trapezius muscles. Clench condition had a significant effect on muscle function (P = 0.0000) with the maximum function obtained for occlusions with bilateral posterior contacts and the mandible in a stable centric position. The remaining contact points and moving the mandible to a protruded position, whilst keeping posterior contacts, resulted in significantly lower muscle activities. Clench condition also had a significant effect on the per cent overlap, anterior-posterior and torque coefficients (P = 0.0000-0.0024), which describe the degree of symmetry in these muscle activities. Bilateral posterior contact conditions had significantly greater symmetry in muscle activities than anterior contact conditions. Activity in the sternocleidomastoid, anterior digastric and trapezius was consistently low for all clench conditions, i.e. centric position, whilst with anterior teeth contacts, both the muscle activity and the degree of symmetry in muscle activity are significantly reduced.

  13. Ambient Occlusion Effects for Combined Volumes and Tubular Geometry

    KAUST Repository

    Schott, M.

    2013-06-01

    This paper details a method for interactive direct volume rendering that computes ambient occlusion effects for visualizations that combine both volumetric and geometric primitives, specifically tube-shaped geometric objects representing streamlines, magnetic field lines or DTI fiber tracts. The algorithm extends the recently presented the directional occlusion shading model to allow the rendering of those geometric shapes in combination with a context providing 3D volume, considering mutual occlusion between structures represented by a volume or geometry. Stream tube geometries are computed using an effective spline-based interpolation and approximation scheme that avoids self-intersection and maintains coherent orientation of the stream tube segments to avoid surface deforming twists. Furthermore, strategies to reduce the geometric and specular aliasing of the stream tubes are discussed.

  14. Efficacy of Endovascular Therapy for Direct Occlusion of Intracranial Aneurysms

    Directory of Open Access Journals (Sweden)

    K Tamrakar

    2011-09-01

    Full Text Available Introduction: Our purpose was to evaluate the effectiveness of endovascular therapy using detachable coils and balloons for the direct occlusion of intracranial aneurysms. Methods: We retrospectively reviewed 563 patients undergoing digital subtraction angiography from January 2007 to July 2009. Two hundred and fi fty patients with 323 embolized intracranial aneurysms were studied. Results: Among 250 patients, 66 % were female and 34 % male, the age ranging from 19 - 83 years (mean 50.66 ± 12.92. One hundred and seventy-seven had a single aneurysm while 73 showed multiple aneurysms. Seventeen (9.6 % had giant aneurysms. Three hundred and eleven aneurysms were treated using detachable coils, and 12 giant aneurysms were embolized by detachable balloons for the parent vessel occlusion. Of 323 aneurysms treated via the endovascular approach, total occlusion was seen in 93 % of the aneurysms, near total occlusion in 5.2 % and incomplete embolization in 1.5 %. Among patients presenting with sub-arachnoid hemorrhage, 62 improved to the Glasgow outcome score (GOS of 5, 93 improved to GOS 4, 14 improved to GOS 3, 10 improved to GOS 2 at the time of discharge and 5 patients died. Angiographic follow-up was scheduled between 6 - 12 months post-embolization. The aneurysm recurred in 1.2 % and were re-embolized using additional coils. Statistically, Hunt and Hess Grade and GOS indicated clinical signifi cance (P 0.05. Conclusions: Hunt and Hess VI and V are considered as poor clinical gradings in aneurysmal SAH. However, endovascular treatment has been established as an effective method to obliterate intracranial aneurysms allowing subsequent decrease in mortality and morbidity. Keywords: detachable coils, detachable balloons, endovascular therapy, intracranial aneurysms.

  15. ALICE HMPID Radiator Vessel

    CERN Multimedia

    2003-01-01

    View of the radiator vessels of the ALICE/HMPID mounted on the support frame. Each HMPID module is equipped with 3 indipendent radiator vessels made out of neoceram and fused silica (quartz) windows glued together. The spacers inside the vessel are needed to stand the hydrostatic pressure. http://alice-hmpid.web.cern.ch/alice-hmpid

  16. Effect of different lateral occlusion schemes on peri-implant strain: A laboratory study

    Science.gov (United States)

    Lo, Jennifer; Palamara, Joseph

    2017-01-01

    PURPOSE This study aims to investigate the effects of four different lateral occlusion schemes and different excursions on peri-implant strains of a maxillary canine implant. MATERIALS AND METHODS Four metal crowns with different occlusion schemes were attached to an implant in the maxillary canine region of a resin model. The included schemes were canine-guided (CG) occlusion, group function (GF) occlusion, long centric (LC) occlusion, and implant-protected (IP) occlusion. Each crown was loaded in three sites that correspond to maximal intercuspation (MI), 1 mm excursion, and 2 mm excursion. A load of 140 N was applied on each site and was repeated 10 times. The peri-implant strain was recorded by a rosette strain gauge that was attached on the resin model buccal to the implant. For each loading condition, the maximum shear strain value was calculated. RESULTS The different schemes and excursive positions had impact on the peri-implant strains. At MI and 1 mm positions, the GF had the least strains, followed by IP, CG, and LC. At 2 mm, the least strains were associated with GF, followed by CG, LC, and IP. However, regardless of the occlusion scheme, as the excursion increases, a linear increase of peri-implant strains was detected. CONCLUSION The peri-implant strain is susceptible to occlusal factors. The eccentric location appears to be more influential on peri-implant strains than the occlusion scheme. Therefore, adopting an occlusion scheme that can reduce the occurrence of occlusal contacts laterally may be beneficial in reducing peri-implant strains. PMID:28243391

  17. Effect of different lateral occlusion schemes on peri-implant strain: A laboratory study.

    Science.gov (United States)

    Lo, Jennifer; Abduo, Jaafar; Palamara, Joseph

    2017-02-01

    This study aims to investigate the effects of four different lateral occlusion schemes and different excursions on peri-implant strains of a maxillary canine implant. Four metal crowns with different occlusion schemes were attached to an implant in the maxillary canine region of a resin model. The included schemes were canine-guided (CG) occlusion, group function (GF) occlusion, long centric (LC) occlusion, and implant-protected (IP) occlusion. Each crown was loaded in three sites that correspond to maximal intercuspation (MI), 1 mm excursion, and 2 mm excursion. A load of 140 N was applied on each site and was repeated 10 times. The peri-implant strain was recorded by a rosette strain gauge that was attached on the resin model buccal to the implant. For each loading condition, the maximum shear strain value was calculated. The different schemes and excursive positions had impact on the peri-implant strains. At MI and 1 mm positions, the GF had the least strains, followed by IP, CG, and LC. At 2 mm, the least strains were associated with GF, followed by CG, LC, and IP. However, regardless of the occlusion scheme, as the excursion increases, a linear increase of peri-implant strains was detected. The peri-implant strain is susceptible to occlusal factors. The eccentric location appears to be more influential on peri-implant strains than the occlusion scheme. Therefore, adopting an occlusion scheme that can reduce the occurrence of occlusal contacts laterally may be beneficial in reducing peri-implant strains.

  18. The mechanics of dental occlusion and disclusion.

    Science.gov (United States)

    Katona, Thomas R; Eckert, George J

    2017-12-01

    The mechanical environment associated with occluding teeth is the foundation for a wide range of research topics, clinical practice and dogma, product development and marketing, and medico-legal issues. The purpose of this study was to experimentally examine the relationships between occlusal factors and their impact on the associated contact forces. Matching pairs of 0°, 20°, 33° and 40° cusp first molar denture teeth were placed into Class I, II and III molar relationships. As the teeth were brought together into occlusion and then separated, the loads experienced by the mandibular tooth were continuously measured by a load cell that was supporting it. Loess smoothing splines were fitted to all data curves to calculate 95% confidence intervals. All lateral force magnitudes and directions were statistically different when compared between classes of occlusion, cusp angles, and occlusion vs. disclusion. Noteworthy counterintuitive observations were that the lateral contact force components were generally higher during disclusion than occlusion, the peak lateral force magnitudes did not always occur when the occlusal force was maximum, and the lateral contact force component magnitude can be larger than the occlusal force. Wedging and friction account for these unexpected results. The data indicate that each occlusion/disclusion cycle is characterized by complex transient loads that may impact wear facet and non-carious cervical lesion formation, implant and restorative failures, various aspects of occlusal trauma, and the concept of axial occlusal loading. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. High mortality of blue, humpback and fin whales from modeling of vessel collisions on the U.S. West Coast suggests population impacts and insufficient protection.

    Science.gov (United States)

    Rockwood, R Cotton; Calambokidis, John; Jahncke, Jaime

    2017-01-01

    Mortality from collisions with vessels is one of the main human causes of death for large whales. Ship strikes are rarely witnessed and the distribution of strike risk and estimates of mortality remain uncertain at best. We estimated ship strike mortality for blue humpback and fin whales in U.S. West Coast waters using a novel application of a naval encounter model. Mortality estimates from the model were far higher than current minimum estimates derived from stranding records and are closer to extrapolations adjusted for detection probabilities of dead whales. Our most conservative model estimated mortality to be 7.8x, 2.0x and 2.7x the U.S. recommended limit for blue, humpback and fin whales, respectively, suggesting that death from vessel collisions may be a significant impediment to population growth and recovery. Comparing across the study area, the majority of strike mortality occurs in waters off California, from Bodega Bay south and tends to be concentrated in a band approximately 24 Nm (44.5 km) offshore and in designated shipping lanes leading to and from major ports. While some mortality risk exists across nearly all West Coast waters, 74%, 82% and 65% of blue, humpback and fin whale mortality, respectively, occurs in just 10% of the study area, suggesting conservation efforts can be very effective if focused in these waters. Risk is highest in the shipping lanes off San Francisco and Long Beach, but only a fraction of total estimated mortality occurs in these proportionally small areas, making any conservation efforts exclusively within these areas insufficient to address overall strike mortality. We recommend combining shipping lane modifications and re-locations, ship speed reductions and creation of 'Areas to be Avoided' by vessels in ecologically important locations to address this significant source of whale mortality.

  20. High mortality of blue, humpback and fin whales from modeling of vessel collisions on the U.S. West Coast suggests population impacts and insufficient protection.

    Directory of Open Access Journals (Sweden)

    R Cotton Rockwood

    Full Text Available Mortality from collisions with vessels is one of the main human causes of death for large whales. Ship strikes are rarely witnessed and the distribution of strike risk and estimates of mortality remain uncertain at best. We estimated ship strike mortality for blue humpback and fin whales in U.S. West Coast waters using a novel application of a naval encounter model. Mortality estimates from the model were far higher than current minimum estimates derived from stranding records and are closer to extrapolations adjusted for detection probabilities of dead whales. Our most conservative model estimated mortality to be 7.8x, 2.0x and 2.7x the U.S. recommended limit for blue, humpback and fin whales, respectively, suggesting that death from vessel collisions may be a significant impediment to population growth and recovery. Comparing across the study area, the majority of strike mortality occurs in waters off California, from Bodega Bay south and tends to be concentrated in a band approximately 24 Nm (44.5 km offshore and in designated shipping lanes leading to and from major ports. While some mortality risk exists across nearly all West Coast waters, 74%, 82% and 65% of blue, humpback and fin whale mortality, respectively, occurs in just 10% of the study area, suggesting conservation efforts can be very effective if focused in these waters. Risk is highest in the shipping lanes off San Francisco and Long Beach, but only a fraction of total estimated mortality occurs in these proportionally small areas, making any conservation efforts exclusively within these areas insufficient to address overall strike mortality. We recommend combining shipping lane modifications and re-locations, ship speed reductions and creation of 'Areas to be Avoided' by vessels in ecologically important locations to address this significant source of whale mortality.

  1. Occlusal status in Asian male adults : Prevalence and ethnic variation

    NARCIS (Netherlands)

    Soh, J; Sandham, John; Chin, Yeen

    The purpose of this study was to determine the occlusal status in young Asian male adults of three ethnic groups. Study models of a sample of male army recruits (N = 339, age 1722 years) with no history of orthodontic treatment were assessed. The ethnic proportions of the sample were Chinese 76.1%

  2. Data for the inhibition effects of recombinant lamprey CRBGP on the tube formation of HUVECs and new blood vessel generation in CAM models

    Directory of Open Access Journals (Sweden)

    Qi Jiang

    2016-03-01

    Full Text Available In the present data article, lamprey cysteine-rich buccal gland protein (CRBGP which belongs to cysteine-rich secretory proteins (CRISPs family was recombinant and expressed in Rosetta blue cells. After identification, the recombinant protein was purified through affinity chromatograph. The inhibition effects of recombinant lamprey CRBGP (rL-CRBGP on tube formation of human umbilical vein endothelial cells (HUVECs and new blood vessel generation in chick chorioallantoic membrane (CAM models were analyzed. This paper contains data related to research concurrently published in “Anti-angiogenic activities of CRBGP from buccal glands of lampreys (Lampetra japonica” [1].

  3. Effect of combination therapy using hypothermia and granulocyte colony-stimulating factor in a rat transient middle cerebral artery occlusion model.

    Science.gov (United States)

    Ghahari, Laya; Safari, Manouchehr; Joghataei, Mohamad Taghi; Mehdizadeh, Mehdi; Soleimani, Mansoureh

    2014-01-01

    Stroke is the third leading cause of death. Hypothermia has been recognized as an effective method in reducing brain injury. In this study, we assessed the effects of granulocyte colony-stimulating factor (G-CSF) as a neuroprotective agent and mild hypothermia on mortality, behavioral function, infarct volume, and brain edema in Wistar rats. Forty male rats were used in five groups (eight rats in each group): control, hypothermy, G-CSF, combination hypothermy + CSF, and sham. Rats were anesthetized by injection of chloral hydrate (400 mg/kg) intraperitoneally. Transient cerebral ischemia was induced by 60-min intraluminal occlusion of left middle cerebral artery. Hypothermia, initiated at the time of reperfusion and G-CSF was started one hour after reperfusion at a dose of 15 mg/kg subcutaneously. The motor behavior was measured using Garcia's index and animals were assigned for the assessments of infarction, brain swelling, and mortality rate. The mortality was 38.46% (control group) and reduced in other groups. Neurological deficit score of control group (40.31 ± 1.56) was significantly lower than in treatment groups. The total cerebral infarct volume of treatment group was significantly lower than control group (43.96 ± 44.05 mm3). Treatment with hypothermy plus G-CSF (2.69 ± 0.24%) could significantly reduce brain swelling volume than other treatment groups. Our major finding is that mild hypothermic treatment plus G-CSF significantly reduced mortality rate and edema and improved neurological function. The results suggest that the combination of hypothermia and G-CSF is more effectively than other treatment groups being used alone.

  4. Progesterone treatment shows greater protection in brain vs. retina in a rat model of middle cerebral artery occlusion: Progesterone receptor levels may play an important role.

    Science.gov (United States)

    Allen, Rachael S; Sayeed, Iqbal; Oumarbaeva, Yuliya; Morrison, Katherine C; Choi, Paul H; Pardue, Machelle T; Stein, Donald G

    2016-11-22

    To determine whether inflammation increases in retina as it does in brain following middle cerebral artery occlusion (MCAO), and whether the neurosteroid progesterone, shown to have protective effects in both retina and brain after MCAO, reduces inflammation in retina as well as brain. MCAO rats treated systemically with progesterone or vehicle were compared with shams. Protein levels of cytosolic NF-κB, nuclear NF-κB, phosphorylated NF-κB, IL-6, TNF-α, CD11b, progesterone receptor A and B, and pregnane X receptor were assessed in retinas and brains at 24 and 48 h using western blots. Following MCAO, significant increases were observed in the following inflammatory markers: pNF-κB and CD11b at 24 h in both brain and retina, nuclear NF-κB at 24 h in brain and 48 h in retina, and TNF-α at 24 h in brain.Progesterone treatment in MCAO animals significantly attenuated levels of the following markers in brain: pNF-κB, nuclear NF-κB, IL-6, TNF-α, and CD11b, with significantly increased levels of cytosolic NF-κB. Retinas from progesterone-treated animals showed significantly reduced levels of nuclear NF-κB and IL-6 and increased levels of cytosolic NF-κB, with a trend for reduction in other markers. Post-MCAO, progesterone receptors A and B were upregulated in brain and downregulated in retina. Inflammatory markers increased in both brain and retina after MCAO, with greater increases observed in brain. Progesterone treatment reduced inflammation, with more dramatic reductions observed in brain than retina. This differential effect may be due to differences in the response of progesterone receptors in brain and retina after injury.

  5. Comparison of applicability of current transition temperature shift models to SA533B-1 reactor pressure vessel steel of Korean nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Ji Hyun; Lee, Bong Sang [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-08-15

    The precise prediction of radiation embrittlement of aged reactor pressure vessels (RPVs) is a prerequisite for the long-term operation of nuclear power plants beyond their original design life. The expiration of the operation licenses for Korean reactors the RPVs of which are made from SA533B-1 plates and welds is imminent. Korean regulatory rules have adopted the US Nuclear Regulatory Commission's transition temperature shift (TTS) models to the prediction of the embrittlement of Korean reactor pressure vessels. The applicability of the TTS model to predict the embrittlement of Korean RPVs made of SA533B-1 plates and welds was investigated in this study. It was concluded that the TTS model of 10 CFR 50.61a matched the trends of the radiation embrittlement in the SA533B-1 plates and welds better than did that of Regulatory Guide (RG) 1.99 Rev. 2. This is attributed to the fact that the prediction performance of 10 CFR 50.61a was enhanced by considering the difference in radiation embrittlement sensitivity among the different types of RPV materials.

  6. Robust visual tracking with contiguous occlusion constraint

    Science.gov (United States)

    Wang, Pengcheng; Qian, Weixian; Chen, Qian

    2016-02-01

    Visual tracking plays a fundamental role in video surveillance, robot vision and many other computer vision applications. In this paper, a robust visual tracking method that is motivated by the regularized ℓ1 tracker is proposed. We focus on investigating the case that the object target is occluded. Generally, occlusion can be treated as some kind of contiguous outlier with the target object as background. However, the penalty function of the ℓ1 tracker is not robust for relatively dense error distributed in the contiguous regions. Thus, we exploit a nonconvex penalty function and MRFs for outlier modeling, which is more probable to detect the contiguous occluded regions and recover the target appearance. For long-term tracking, a particle filter framework along with a dynamic model update mechanism is developed. Both qualitative and quantitative evaluations demonstrate a robust and precise performance.

  7. Occlusion management of implant-supported prostheses

    OpenAIRE

    Delmas, Marion

    2017-01-01

    The implant solution has become the treatment of choice to replace missing teeth and to help in the retention of complete denture. Dental implants have different biological and biomechanical characteristics than natural teeth. Occlusion of implant-supported prostheses is considered to be one of the most important factors contributing to implant success. This thesis aims to review current recommendations for occlusal management of implant-supported prosthesis. The known and applied occlusal co...

  8. Occlusion and periodontics: a critical literature review

    OpenAIRE

    Flávia Aparecida Chaves FURLANETO; Luiz Gustavo Nascimento de MELO; Maria José Hitomi NAGATA; Alvaro Francisco BOSCO; Tatiana Miranda DELIBERADOR; Michel Reis MESSORA; Alicio Rosalino GARCIA

    2009-01-01

    Introduction: Occlusal trauma is defined as an injury resulting intissues changes within the attachment apparatus as result of occlusalforce(s). Since 1901, when Karolyi reported a possible interactionbetween occlusal disharmony and periodontal alterations, severalstudies have tried to find scientific evidence that corroborates or not this interrelationship. Objective and literature review: In this paper,the authors review the studies that have analyzed traumatic occlusion as a presumed aggra...

  9. Mechanosensing in developing lymphatic vessels.

    Science.gov (United States)

    Planas-Paz, Lara; Lammert, Eckhard

    2014-01-01

    The lymphatic vasculature is responsible for fluid homeostasis, transport of immune cells, inflammatory molecules, and dietary lipids. It is composed of a network of lymphatic capillaries that drain into collecting lymphatic vessels and ultimately bring fluid back to the blood circulation. Lymphatic endothelial cells (LECs) that line lymphatic capillaries present loose overlapping intercellular junctions and anchoring filaments that support fluid drainage. When interstitial fluid accumulates within tissues, the extracellular matrix (ECM) swells and pulls the anchoring filaments. This results in opening of the LEC junctions and permits interstitial fluid uptake. The absorbed fluid is then transported within collecting lymphatic vessels, which exhibit intraluminal valves that prevent lymph backflow and smooth muscle cells that sequentially contract to propel lymph.Mechanotransduction involves translation of mechanical stimuli into biological responses. LECs have been shown to sense and respond to changes in ECM stiffness, fluid pressure-induced cell stretch, and fluid flow-induced shear stress. How these signals influence LEC function and lymphatic vessel growth can be investigated by using different mechanotransduction assays in vitro and to some extent in vivo.In this chapter, we will focus on the mechanical forces that regulate lymphatic vessel expansion during embryonic development and possibly secondary lymphedema. In mouse embryos, it has been recently shown that the amount of interstitial fluid determines the extent of lymphatic vessel expansion via a mechanosensory complex formed by β1 integrin and vascular endothelial growth factor receptor-3 (VEGFR3). This model might as well apply to secondary lymphedema.

  10. An innovative short-stay health care model for treatment of uncomplicated vaso-occlusive crisis in adult sickle cell disease patients in Canada to reduce emergency department utilization.

    Science.gov (United States)

    Binding, Andrew; Ward, Richard; Phua, Chai; Naessens, Veronique; O'Brien, Tara; Bhatia, Sacha; Baranek, Hayley; Marani, Husayn; Mukerji, Geetha

    2017-10-17

    Patients with sickle cell disease (SCD) with vaso-occlusive crises (VOC) often visit the emergency department (ED) for management of painful episodes. The primary objective of this pilot study was to evaluate the acceptability of a short-stay model for treatment of VOC in SCD outside of the ED in Toronto, Canada. Secondary objectives were to assess patient satisfaction of this model, barriers to its use and comparison of clinical outcomes to a historical control. Adult SCD patients with symptoms of an uncomplicated VOC between October 2014 to July 2016 were managed according to best practice recommendations in a short-stay unit as an alternative to the local emergency room. Primary outcome of time to first analgesia, and secondary outcome of discharge rate were compared to a historical control at a local ED from 2009-2012. Satisfaction and barriers to use of the ambulatory care delivery model were assessed by patient survey. Twenty-one visits were recorded at the short-stay unit during the study period. Average time to first opiate dose was 23.5 minutes in the short-stay unit compared to 100.3 minutes in the ED (p4/5 on Likert scale) except for geographic accessibility (85% response rate, n=18). This study demonstrated high patient satisfaction and acceptability of a short-stay model for treatment of uncomplicated VOC in adult SCD patients in Toronto, the first of its kind in Canada.

  11. An experimental investigation of the hemodynamic variations due to aplastic vessels within three-dimensional phantom models of the Circle of Willis.

    LENUS (Irish Health Repository)

    Fahy, Paul

    2013-09-10

    A complete circle of Willis (CoW) is found in approximately 30-50% of the population. Anatomical variations, such as absent or surgically clamped vessels, can result in undesirable flow patterns. These can affect the brain\\'s ability to maintain cerebral perfusion and the formation of cerebral aneurysms. An experimental test system was developed to simulate cerebral physiological conditions through three flexible 3D patient-specific models of complete and incomplete CoW geometries. Flow visualizations were performed with isobaric dyes and the mapped dye streamlines were tracked throughout the models. Three to seven flow impact locations were observed for all configurations, corresponding to known sites for aneurysmal formation. Uni and bi-directional cross-flows occurred along the communicating arteries. The greatest shunting of flow occurred for a missing pre-communicating anterior (A1) and posterior (P1) cerebral arteries. The anterior cerebral arteries had the greatest reduction (15-37%) in efferent flow rates for missing either a unilateral A1 or bilateral P1 segments. The bi-directional cross-flows, with multiple afferent flow mixing, observed along the communicating arteries may explain the propensity of aneurysm formation at these sites. Reductions in efferent flow rates due to aplastic vessel configurations may affect normal brain function.

  12. Assessment of occlusion curriculum in predoctoral dental education: report from ACP Task Force on Occlusion Education.

    Science.gov (United States)

    Lee, Damian J; Wiens, Jonathan P; Ference, John; Donatelli, David; Smith, Rick M; Dye, Bryan D; Obrez, Ales; Lang, Lisa A

    2012-10-01

    The purposes of this report were to (1) assess the current occlusion curriculum in the predoctoral prosthodontic education of US dental institutions and (2) to examine the opinions of faculty, course directors, and program directors on the contents of occlusion curriculum. The Task Force on Occlusion Education from the American College of Prosthodontists (ACP) conducted two surveys using a web-based survey engine: one to assess the current status of occlusion education in predoctoral dental education and another to examine the opinions of faculty and course directors on the content of occlusion curriculum. The sections in the surveys included demographic information, general curriculum information, occlusion curriculum for dentate patients, occlusion curriculum for removable prosthodontics, occlusion curriculum for implant prosthodontics, temporomandibular disorder (TMD) curriculum, teaching philosophy, concepts taught, and methods of assessment. The results from the surveys were compiled and analyzed using descriptive statistics. The results from the two surveys on general concepts taught in occlusion curriculum were sorted and compared for discrepancies. According to the predoctoral occlusion curriculum surveys, canine guidance was preferred for dentate patients, fixed prosthodontics, and fixed implant prosthodontics. Bilateral balanced occlusion was preferred for removable prosthodontics and removable implant prosthodontics. There were minor differences between the two surveys regarding the occlusion concepts being taught and the opinions of faculty members teaching occlusion. Two surveys were conducted regarding the current concepts being taught in occlusion curriculum and the opinions of educators on what should be taught in occlusion curriculum. An updated and clearly defined curriculum guideline addressing occlusion in fixed prosthodontics, removable prosthodontics, implant prosthodontics, and TMD is needed. © 2012 by the American College of Prosthodontists.

  13. Measurement of mandibular movements in parafunctional patient using occlusal splint with Bragg gratings: pilot study

    Science.gov (United States)

    Franco, Ana Paula G. O.; Gebert, Andréa. O.; Souza, Mauren A.; Jeranoski, Lorena; Kalinowski, Hypolito J.; Abe, Ilda

    2016-05-01

    The aim of the study is to demonstrate the potential of the fibre Braggs grating (FBG) in the measurement of different jaw movements that are performed for patients with occlusal parafunction using occlusal splints. Two silicon plates each 2mm are used, the fibre optic sensor is positioned in the maxillary left first molar region above the point of contact with opposing tooth after pressing the first plate on the model. Then the second silicon plate is pressed. The device has a final thickness of 2 mm. The occlusal splint is installed in the mouth of the patient who underwent different movements on occlusal splint. The maximum frequency bite is monitored. The results demonstrate that the bite shows a difference between grinding and clenching movements. The curves behaviour patterns are presented in order to show these different comparisons. Therefore, it is concluded that the fibre Braggs grating consists in an efficient method for monitoring the mechanical behaviour bite of patients with occlusal splints.

  14. Radial optic neurotomy in the porcine eye without retinal vein occlusion.

    Science.gov (United States)

    Czajka, Marcin P; Cummings, Thomas J; McCuen, Brooks W; Toth, Cynthia A; Nguyen, Hoang; Fekrat, Sharon

    2004-08-01

    To demonstrate the histopathologic changes in the porcine eye without retinal vein occlusion after radial optic neurotomy (RON). A RON was performed in 14 normal eyes of 12 Yorkshire Cross pigs. One radial stab incision at the edge of the nasal optic nerve head was made using a 20-gauge microvitreoretinal blade (Visitec) while the intraocular pressure was elevated. Surgery was concluded when hemostasis was achieved. Weekly ophthalmoscopic examinations were performed. Group 1 eyes (4 eyes of 2 pigs) were enucleated at the end of surgery. Group 2 eyes (4 eyes of 4 pigs) were enucleated 1 week postoperatively, and group 3 eyes (4 eyes of 4 pigs) were enucleated 3 weeks postoperatively. In group 4 (2 eyes of 2 pigs), animals underwent vitrectomy and RON, and eyes were enucleated 3 weeks postoperatively. Ophthalmoscopic examination demonstrated engorged blood vessels at the RON site up to 3 weeks after surgery with minimal or no hemorrhage. Histological examination of the optic nerve demonstrated foci of hemorrhage, interstitial edema, reactive gliosis, and rare inflammatory cells. At 3 weeks, there was complete axonal nerve fiber loss distal to the neurotomy site. After RON, marked gliosis and complete axonal nerve fiber loss occur at the neurotomy site. Although bleeding was rare intraoperatively in this porcine model, hemorrhage and interstitial edema were present within the optic nerve at the neurotomy site histologically. Clinical Relevance Radial optic neurotomy remains a controversial method of treatment for central retinal vein occlusion. To our knowledge, this is the first study in the literature describing the histopathologic findings after RON.

  15. Experimental validation of videoendoscopic isolation and occlusion of the bloodflow in open ductus arteriosus.

    Science.gov (United States)

    Vasilenko, Yu V; Kim, A I; Kotov, S A

    2003-03-01

    The potentialities of videoendoscopic isolation and extravasal occlusion of large vessels with titanium clips were studied in acute and chronic experiments on 36 animals and anatomic studies on 5 human cadavers. The number and optimal sites for insertion of trocars and disposition of instruments and thoracoscope for isolation of open ductus arteriosus were determined. A method for videoendoscopic isolation of vessels is developed and possible complications and measures for their liquidation evaluated. High efficiency and low traumatism of videoendoscopic operation are proven under condition of strict adherence to methodology and sufficient qualification of the surgeon in endosurgical manipulations.

  16. Lower Body Positive Pressure Application with an Antigravity Suit in Acute Carotid Occlusion

    Directory of Open Access Journals (Sweden)

    Karine Berthet

    2010-01-01

    Full Text Available The challenge in acute stroke is still to reperfuse as early as possible the ischemic territory. Since fibrinolytic therapies have a limited window with potential risk of bleeding, having a nonpharmacologic mean to recruit vessels in area surrounding necrosis might be useful. We propose here to use antigravity suit inflated at “venous” pressure levels to shift blood towards thoracic and brain territories. We report two cases of spectacular clinical recovery after acute carotid occlusion.

  17. Lower body positive pressure application with an antigravity suit in acute carotid occlusion.

    Science.gov (United States)

    Berthet, Karine; Lukaszewicz, Anne Claire; Bousser, Marie-Germaine; Payen, Didier

    2010-04-01

    The challenge in acute stroke is still to reperfuse as early as possible the ischemic territory. Since fibrinolytic therapies have a limited window with potential risk of bleeding, having a nonpharmacologic mean to recruit vessels in area surrounding necrosis might be useful. We propose here to use antigravity suit inflated at "venous" pressure levels to shift blood towards thoracic and brain territories. We report two cases of spectacular clinical recovery after acute carotid occlusion.

  18. Pressure vessel design manual

    CERN Document Server

    Moss, Dennis R

    2013-01-01

    Pressure vessels are closed containers designed to hold gases or liquids at a pressure substantially different from the ambient pressure. They have a variety of applications in industry, including in oil refineries, nuclear reactors, vehicle airbrake reservoirs, and more. The pressure differential with such vessels is dangerous, and due to the risk of accident and fatality around their use, the design, manufacture, operation and inspection of pressure vessels is regulated by engineering authorities and guided by legal codes and standards. Pressure Vessel Design Manual is a solutions-focused guide to the many problems and technical challenges involved in the design of pressure vessels to match stringent standards and codes. It brings together otherwise scattered information and explanations into one easy-to-use resource to minimize research and take readers from problem to solution in the most direct manner possible. * Covers almost all problems that a working pressure vessel designer can expect to face, with ...

  19. An experimental canine patent ductus arteriosus occlusion device based on shape memory polymer foam in a nitinol cage.

    Science.gov (United States)

    Wierzbicki, Mark A; Raines, Sarah B; Gordon, Sonya G; Criscione, John C; Saunders, Ashley B; Birch, Scott; Due, Bradley; Keller, Brandis; Nash, Landon D; Miller, Matthew W; Maitland, Duncan J

    2017-11-01

    Patent ductus arteriosus (PDA) is a congenital cardiovascular defect in which a fetal connection between the aorta and pulmonary artery does not spontaneously close shortly after birth. If left uncorrected serious complications and even death can occur. Surgical ligation is the traditional treatment method; however, it is an invasive procedure, that motivates development of a minimally invasive option. Shape memory polymer (SMP) foams are unique materials that hold promise in the field of minimally invasive occlusion devices. In this work, a prototype nitinol foam cage (NFC) incorporating SMP foams has been designed and evaluated in multiple mechanical and in vitro verification tests. The NFC demonstrated acceptable fatigue resistance in a preliminary strut integrity test, withstanding one million cycles without complete strut fracture. Radial force analysis of both thick- and thin-walled prototype variations generated less vessel distension and wall tension in a vessel mimic compared to a commercial device. The NFCs exhibited negligible in vitro migration, comparable to that of a commercial device, using simplified, ideal models of PDA. Deployment characteristics of the prototypes were evaluated and compared to that of a commercial device when delivered into physiological models of PDA. During mock deployments, a veterinary cardiologist noted that, while deliverable, the thin-walled NFC prototype exhibited poor deployment characteristics, however the thick-walled NFC had deployment characteristics comparable to that of a commercial device. The promising results of this study warrant further investigation of the NFC device for canine PDA closure. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Techniques for transcatheter recanalization of completely occluded vessels and pathways in patients with congenital heart disease

    Directory of Open Access Journals (Sweden)

    Latson Larry

    2010-01-01

    Full Text Available Occlusions of major vessels in patients with congenital heart disease may occur due to a variety of factors. These occlusions are often felt to be best addressed surgically; however, we and others have been successful in recanalizing most of these vessels in the catheterization laboratory. Most of these patients will require multiple procedures in the catheterization laboratory to ensure vessel patency and to facilitate vessel growth. Physicians performing the procedure should have a thorough understanding of the anatomic considerations for the intended procedure and have access to a variety of devices and equipment to optimize the result of the procedure. In this article, we review some of the technical aspects that are vital for the success of the procedure.

  1. Hippocampal neurogenesis in the new model of global cerebral ischemia

    Science.gov (United States)

    Kisel, A. A.; Chernysheva, G. A.; Smol'yakova, V. I.; Savchenko, R. R.; Plotnikov, M. B.; Khodanovich, M. Yu.

    2015-11-01

    The study aimed to evaluate the changes of hippocampal neurogenesis in a new model of global transient cerebral ischemia which was performed by the occlusion of the three main vessels (tr. brachiocephalicus, a. subclavia sinistra, and a. carotis communis sinistra) branching from the aortic arch and supplying the brain. Global transitory cerebral ischemia was modeled on male rats (weight = 250-300 g) under chloral hydrate with artificial lung ventilation. Animals after the same surgical operation without vessel occlusion served as sham-operated controls. The number of DCX-positive (doublecortin, the marker of immature neurons) cells in dentate gyrus (DG) and CA1-CA3 fields of hippocampus was counted at the 31st day after ischemia modeling. It was revealed that global cerebral ischemia decreased neurogenesis in dentate gyrus in comparison with the sham-operated group (Pneurogenesis in CA1-CA3 fields was increased as compared to the control (P<0.05).

  2. PARACENTRAL ACUTE MIDDLE MACULOPATHY ASSOCIATED WITH RETINAL ARTERY OCCLUSION AFTER COSMETIC FILLER INJECTION.

    Science.gov (United States)

    Sridhar, Jayanth; Shahlaee, Abtin; Shieh, Wen-Shi; Rahimy, Ehsan

    2017-01-01

    To report a single case of paracentral acute middle maculopathy in association with retinal artery occlusion in the setting of ipsilateral facial cosmetic filler injection. Case report. A 35-year-old woman presenting with sudden vision loss to finger count vision immediately after left nasal fat pad cosmetic filler injection. Dilated funduscopic examination revealed a swollen optic disc with multiple branch arterial occlusions with visible embolic material. Fluorescein angiography confirmed multiple branch arterial occlusions in addition to a focal choroidal infarction in the macula. Spectral-domain optical coherence tomography revealed middle retinal hyperreflectivity in the superotemporal macula consistent with paracentral acute middle maculopathy. En face optical coherence tomography demonstrated a superotemporal area of whitening at the level of the deep capillary plexus corresponding to the paracentral acute middle maculopathy lesion seen on spectral-domain optical coherence tomography. On twelve-month follow-up, final visual acuity was 20/100 due to optic neuropathy. Emboli from cosmetic facial filler injections may rarely result in ipsilateral arterial occlusions and now have a novel association with paracentral acute middle maculopathy likely due to deep capillary plexus feeder vessel occlusion.

  3. Analysis of decrease in lung perfusion blood volume with occlusive and non-occlusive pulmonary embolisms

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Yohei, E-mail: ypfranky1@ybb.ne.jp [Department of Radiology, Niigata University Graduate School of Medical and Dental Science (Japan); Yoshimura, Norihiko [Department of Radiology, Niigata University Graduate School of Medical and Dental Science (Japan); Hori, Yoshiro [Department of Radiology, Showa University Fujigaoka Hospital (Japan); Horii, Yosuke; Ishikawa, Hiroyuki [Department of Radiology, Niigata University Graduate School of Medical and Dental Science (Japan); Yamazaki, Motohiko [Department of Radiology, Niigata City General Hospital (Japan); Noto, Yoshiyuki [Department of Radiology, Niigata University Medical and Dental Hospital (Japan); Aoyama, Hidefumi [Department of Radiology, Niigata University Graduate School of Medical and Dental Science (Japan)

    2014-12-15

    Highlights: • The proportion of preserved PE lesions in the non-occlusive group was 76.7% (33/43). • HUs of the iodine map were significantly higher in the non-occlusive group than in the occlusive group. • There was no significant difference in HUs between the non-occlusive and corresponding normal group. - Abstract: Purpose: The aim of this study was to determine if lung perfusion blood volume (lung PBV) with non-occlusive pulmonary embolism (PE) differs quantitatively and visually from that with occlusive PE and to investigate if lung PBV with non-occlusive PE remains the same as that without PE. Materials and methods: Totally, 108 patients suspected of having acute PE underwent pulmonary dual-energy computed tomography angiography (DECTA) between April 2011 and January 2012. Presence of PE on DECTA was evaluated by one radiologist. Two radiologists visually evaluated the PE distribution (segmental or subsegmental) and its nature (occlusive or non-occlusive) on DECTA and classified perfusion in lung PBV as “decreased,” “slightly decreased,” and “preserved”. Two radiologists used a lung PBV application to set a region of interest (ROI) in the center of the lesion and measured HU values of an iodine map. In the same slice as the ROI of the lesion and close to the lesion, another ROI was set in the normal perfusion area without PE, and HUs were measured. The proportion of lesions was compared between the occlusive and non-occlusive groups. HUs were compared among the occlusive, non-occlusive, and corresponding normal groups. Results: Twenty-five patients had 80 segmental or subsegmental lesions. There were 37 and 43 lesions in the occlusive and non-occlusive groups, respectively. The proportion of decreased lesions was 73.0% (27/37) in the occlusive group, while that of preserved lesions in the non-occlusive group was 76.7% (33/43). There was a significant difference in the proportion of lesions (P < 0.001) between the two groups. HUs of the

  4. The prevalence of questionable occlusal caries

    DEFF Research Database (Denmark)

    Makhija, Sonia K; Gilbert, Gregg H; Funkhouser, Ellen

    2012-01-01

    Questionable occlusal caries (QOC) can be defined as clinically suspected caries with no cavitation or radiographic evidence of occlusal caries. To the authors' knowledge, no one has quantified the prevalence of QOC, so this quantification was the authors' objective in conducting this study...

  5. Dental occlusion and postural control in adults.

    Science.gov (United States)

    Tardieu, Corinne; Dumitrescu, Michel; Giraudeau, Anne; Blanc, Jean-Luc; Cheynet, François; Borel, Liliane

    2009-01-30

    We studied the influence of a dental occlusion perturbation on postural control. The tests were performed in three dental occlusion conditions: (Rest Position: no dental contact, Maximal Intercuspal Occlusion: maximal dental contact, and Thwarted Laterality Occlusion: simulation of a dental malocclusion) and four postural conditions: static (stable platform) and dynamic (unstable platform), with eyes open and eyes closed. A decay of postural control was noted between the Rest Position and Thwarted Laterality Occlusion conditions with regard to average speed and power indexes in dynamic conditions and with eyes closed. However, the head position and stabilization were not different from those in the other experimental conditions, which means that the same functional goal was reached with an increase in the total energetic cost. This work shows that dental occlusion differently affects postural control, depending on the static or dynamic conditions. Indeed, dental occlusion impaired postural control only in dynamic postural conditions and in absence of visual cues. The sensory information linked to the dental occlusion comes into effect only during difficult postural tasks and its importance grows as the other sensory cues become scarce.

  6. Occlusion on oral implants: current clinical guidelines.

    Science.gov (United States)

    Koyano, K; Esaki, D

    2015-02-01

    Proper implant occlusion is essential for adequate oral function and the prevention of adverse consequences, such as implant overloading. Dental implants are thought to be more prone to occlusal overloading than natural teeth because of the loss of the periodontal ligament, which provides shock absorption and periodontal mechanoreceptors, which provide tactile sensitivity and proprioceptive motion feedback. Although many guidelines and theories on implant occlusion have been proposed, few have provided strong supportive evidence. Thus, we performed a narrative literature review to ascertain the influence of implant occlusion on the occurrence of complications of implant treatment and discuss the clinical considerations focused on the overloading factors at present. The search terms were 'dental implant', 'dental implantation', 'dental occlusion' and 'dental prosthesis'. The inclusion criteria were literature published in English up to September 2013. Randomised controlled trials (RCTs), prospective cohort studies and case-control studies with at least 20 cases and 12 months follow-up interval were included. Based on the selected literature, this review explores factors related to the implant prosthesis (cantilever, crown/implant ratio, premature contact, occlusal scheme, implant-abutment connection, splinting implants and tooth-implant connection) and other considerations, such as the number, diameter, length and angulation of implants. Over 700 abstracts were reviewed, from which more than 30 manuscripts were included. We found insufficient evidence to establish firm clinical guidelines for implant occlusion. To discuss the ideal occlusion for implants, further well-designed RCTs are required in the future. © 2014 John Wiley & Sons Ltd.

  7. Effects of Intravitreal Dexamethasone Implants on Retinal Oxygen Saturation, Vessel Diameter, and Retrobulbar Blood Flow Velocity in ME Secondary to RVO.

    Science.gov (United States)

    Eibenberger, Katharina; Schmetterer, Leopold; Rezar-Dreindl, Sandra; Wozniak, Piotr; Told, Reinhard; Mylonas, Georgios; Krall, Christoph; Schmidt-Erfurth, Ursula; Sacu, Stefan

    2017-10-01

    To investigate the effects of intravitreal 0.7 mg dexamethasone implants (Ozurdex) on arterial and venous oxygen saturation, retinal vessel diameter, and retrobulbar blood flow velocity in patients with macular edema (ME) due to retinal vein occlusion (RVO). This prospective, nonrandomized clinical trial included 40 eyes of 40 patients with ME due to RVO. Measurements of arterial and venous oxygen saturation and retinal vessel diameters were performed using the Dynamic Vessel Analyzer. The main outcome measure was the retinal arteriovenous oxygen difference, calculated as the difference between arterial and venous oxygenation. Color Doppler imaging was performed for measuring peak systolic velocity (PSV), end diastolic velocity (EDV), and resistive index (RI) in ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary arteries (PCAs). Follow-up was monthly for 6 months following an initial dexamethasone implant injection. As statistical analysis, a mixed model was performed to investigate the effect treatment. The arteriovenous oxygen difference showed a significant increase (P 0.05), while the venous oxygen saturation and diameter decreased significantly (P 0.05). In patients with RVO, intravitreal dexamethasone treatment leads to an increase in arteriovenous oxygen saturation difference indicating improved retinal oxygenation. Arterial oxygenation and vessel diameter showed no response, whereas venous oxygenation and vessel diameter decreased after treatment.

  8. Measuring Palatal Height in Normal Occlusion and Malocclusions

    Directory of Open Access Journals (Sweden)

    M. Zarringhalam

    2004-12-01

    Full Text Available Statement of Problem: Due to the appearance of palatal height difference in orthodontic patients we decided to carry out this study.Purpose: The purpose of this research was to determine palatal height in persons with normal occlusion and different malocclusions (class I, II Div I and III and comp aring them with each other.Materials and Methods : In this cross sectional research, 240 subjects were selected. Sixty cases (30 girls and 30 boys with normal occlusion within 16-18 years old were selected inrandom cluster sampling from high schools in Mashhad. Examination technique was direct observation, lateral cephalometric radiography, impression and preparing study model for measuring. For every kind of malocclusion 60 young patients, 30 females and 30 males,within the range of 16-20 years old attended orthodontic treatment in private dental offices or Orthodontics Department of Mashhad Dental School .The examination technique was indirect observation, using lateral cephalometry selected of 5395 lateral cephalograms andrelated study models for measuring. Mean, min imum and maximum and height of the palate was initially determined and then normal occlusion was compared with every kind of malocclusion using SPSS statistical software. One way analysis of variance (ANOVA andt-test (independent groups, and also Duncan test were used for comparison.Results: The ANOVA test showed that there were no statistically significant differences between females in normal occlusion and different malocclusions (P=0.486. In boys the palatal height was significantly higher in class III males than class II and class Imalocclusions and the height of palate for normal boys is significantly higher than class I malocclusion (P<0.05. Comparison of other groups was not significantly different.In each group height of palate was significantly lower in females than males (P<0.001.Conclusion: From this research we concluded that palatal height is different in females and males

  9. Large blood vessel stretch in lumbar spine through anterior surgical approach: An experimental study in adult goat

    Directory of Open Access Journals (Sweden)

    Liehua Liu

    2014-01-01

    Full Text Available Background: Various anterior lumbar surgical approaches, including the minimally invasive approach, have greatly improved in recent years. Vascular complications resulting from ALIF are frequently reported. Little information is available about the safety of large blood vessel stretch. We evaluated the right side stretch limit (RSSL of the abdominal aorta (AAA and the inferior vena cava (IVC without blood flow occlusion and investigated stretch-induced histological injury and thrombosis in the iliac and femoral arteries and veins and the stretched vessels. Materials and Methods: The RSSL of blood vessels in five adult goats was measured by counting the number of 0.5-cm-thick wood slabs that were inserted between the right lumbar edge and the stretch hook. Twenty seven adult goats were divided into three groups to investigate histological injury and thrombosis under a stretch to 0.5 cm (group I 1.5 cm (group II for 2 h, or no stretch (group III. Blood vessel samples from groups I and II were analyzed on postsurgical days 1, 3, and 7. Thrombogenesis was examined in the iliac and femoral arteries and veins. Results: The RSSL of large blood vessels in front of L4/5 was 1.5 cm from the right lumbar edge. All goats survived surgery without complications. No injury or thrombosis in the large blood vessels in front of the lumbar vertebrae and in the iliac or femoral arteries and veins was observed. Under light microscopy, group I showed slight swelling of endothelial cells in the AAA and no histological injury of the IVC. The AAA of group II showed endothelial cell damage, unclear organelles, and incomplete cell connections by electron microscopy. Conclusions: The AAA and IVC in a goat model can be stretched by ≤0.5 cm, with no thrombosis in the AAA, IVC, iliac or femoral arteries and veins.

  10. Mesiodistal angulation of the lateral teeth to the functional occlusal plane in normal occlusions

    Directory of Open Access Journals (Sweden)

    Hiroshi Ueda

    2016-01-01

    Full Text Available Introduction: Crowding is a malocclusion with irregularly positioned teeth caused by arch length discrepancy (ALD. Its incidence is high compared with the various malocclusions. In a previous study the crowns of the maxillary lateral teeth had erupted mesially in relation to the functional occlusal plane (FOP in patients with Angle Class I malocclusion and highly erupted canines, which had been uprighted by non-extraction orthodontic treatment, yet these results were based on only two cases evaluated by using plaster models. Therefore, the aim of this study was to assess the mesiodistal angulations of both maxillary and mandibular teeth relative to the FOP in normal occlusion by means of cephalograms and identifying the teeth axial factors contributing to the normal dentitions with the least ALD. Materials and Methods: Thirty Japanese young adult patients (6 males, 24 females with normal occlusion were selected to participate in this study; cephalograms were procured from each and the FOP was used as a reference plane for measuring the changes in the axial angulation along with other indicators of vertical growth. Results: Progressive mesial tipping of the maxillary lateral teeth was observed. First premolars tended to express this more than the second premolars but the tipping values were roughly 90° relative to the FOP on the first molars. Conclusion: The maxillary lateral teeth are more mesially angulated compared to the mandibular ones relative to the FOP. Furthermore, progressive mesial tipping of the maxillary lateral teeth was detected, of which axial angulations were significantly correlated to each other, in spite the mandibular premolars and molars being angulated in a similar fashion.

  11. A controversy with respect to occlusion

    Directory of Open Access Journals (Sweden)

    Shunji Fukushima, DDS, PhD

    2016-08-01

    Full Text Available There are very little controversies on occlusion in healthy individuals, where centric relation is regarded as the criterion for assessing the present occlusion and also for establishing a new occlusal relationship between the upper and the lower jaws. On the other hand, the occlusal position in patients with deformed condyles still remains to be clarified. In this review, the effectiveness and limits of centric relation in these patients are discussed. In addition, the muscle induced occlusal positions, such as the muscular position and the terminal positions of habitual closing movements, are suggested as a substitution for centric relation. Finally, the importance of a stable intercuspal position, where the habitual closing movements terminate without any premature tooth contact, is emphasized.

  12. [Occlusion, mandibular position and orthodontic treatment].

    Science.gov (United States)

    Bai, Ding; Han, Xianglong

    2013-08-01

    One of the ultimate goals for orthodontic treatment is to establish an esthetic, healthy, stable and efficient occlusion. Currently, however, most of the criteria are limited to static occlusion, with little attention to dynamic occlusion. During the therapy, the orthodontists may sometimes find the maximum intercuspation (MI) is remarkably inconsistent with the centric relation (CR), or the mandibular positions are different before and after the therapy. These definitely will influence the stability of the treatment, or even the health of temporomandibular joint (TMJ) and stomatognathic system. The functional occlusion theory emphasizes that the displacement of TMJ in the glenoid fossa is the reason for the inharmony between MI and CR, and the relapse. What is more, this theory also gives the orthodontists the ways to evaluate the relationships among the MI, CR and TMJ. In this paper, we will introduce the contents and methods of the functional occlusion theory.

  13. A controversy with respect to occlusion.

    Science.gov (United States)

    Fukushima, Shunji

    2016-08-01

    There are very little controversies on occlusion in healthy individuals, where centric relation is regarded as the criterion for assessing the present occlusion and also for establishing a new occlusal relationship between the upper and the lower jaws. On the other hand, the occlusal position in patients with deformed condyles still remains to be clarified. In this review, the effectiveness and limits of centric relation in these patients are discussed. In addition, the muscle induced occlusal positions, such as the muscular position and the terminal positions of habitual closing movements, are suggested as a substitution for centric relation. Finally, the importance of a stable intercuspal position, where the habitual closing movements terminate without any premature tooth contact, is emphasized.

  14. Transient evolution of inter vessel gap pressure due to relative thermal expansion between two vessels

    Science.gov (United States)

    Natesan, K.; Selvaraj, P.; Chellapandi, P.; Chetal, S. C.

    2002-08-01

    In a typical liquid metal cooled fast breeder reactor (LMFBR), a cylindrical sodium filled main vessel, which carries the internals such as reactor core, pumps, intermediate heat exchangers etc. is surrounded by another vessel called safety vessel. The inter vessel gap is filled with nitrogen. During a thermal transient in the pool sodium, because of the relative delay involved in the thermal diffusion between MV and SV, they are subjected to relative thermal expansion or contraction between them. This in turn results in pressurisation and depressurisation of inter vessel gap nitrogen respectively. In order to obtain the external pressurization for the buckling design of MV, transient thermal models for obtaining the evolutions of MV, SV and inter gap nitrogen temperatures and hence their relative thermal expansion and inter vessel gap pressure have been developed. This paper gives the details of the mathematical model, assumptions made in the calculation and the results of the analysis.

  15. Occlusion for stimulus deprivation amblyopia

    Science.gov (United States)

    Antonio-Santos, Aileen; Vedula, Satyanarayana S; Hatt, Sarah R; Powell, Christine

    2014-01-01

    Background Stimulus deprivation amblyopia (SDA) develops due to an obstruction to the passage of light secondary to a condition such as cataract. The obstruction prevents formation of a clear image on the retina. SDA can be resistant to treatment, leading to poor visual prognosis. SDA probably constitutes less than 3% of all amblyopia cases, although precise estimates of prevalence are unknown. In developed countries, most patients present under the age of one year; in less developed parts of the world patients are likely to be older at the time of presentation. The mainstay of treatment is removal of the cataract and then occlusion of the better-seeing eye, but regimens vary, can be difficult to execute, and traditionally are believed to lead to disappointing results. Objectives Our objective was to evaluate the effectiveness of occlusion therapy for SDA in an attempt to establish realistic treatment outcomes. Where data were available, we also planned to examine evidence of any dose response effect and to assess the effect of the duration, severity, and causative factor on the size and direction of the treatment effect. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 9), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to October 2013), EMBASE (January 1980 to October 2013), the Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2013), PubMed (January 1946 to October 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 28 October 2013. Selection criteria We planned

  16. Special report: Occlusive cuff controller

    Science.gov (United States)

    Baker, J. T.

    1975-01-01

    A mechanical occlusive cuff controller suitable for blood flow experiments in space shuttle flights is described. The device requires 115 volt ac power and a pressurized gas source. Two occluding cuff pressures (30 and 50 mmHg) are selectable by a switch on the front panel. A screw driver adjustment allows accurate cuff pressurization levels for under or oversized limbs. Two pressurization cycles (20 second and 2 minutes) can be selected by a front panel switch. Adjustment of the timing cycles is also available through the front panel. A pushbutton hand switch allows remote start of the cuff inflation cycle. A stop/reset switch permits early termination of the cycle and disabling of the controller to prevent inadvertent reactivation. Pressure in the cuff is monitored by a differential aneroid barometer. In addition, an electrocardiogram trigger circuit permits the initiation of the pressurization cycle by an externally supplied ECG cycle.

  17. Permanent Distal Occlusion of Middle Cerebral Artery in Rat Causes Local Increased ETB, 5-HT1B and AT1 Receptor-Mediated Contractility Downstream of Occlusion

    DEFF Research Database (Denmark)

    Rasmussen, Marianne N P; Hornbak, Malene; Larsen, Stine S

    2013-01-01

    a model of permanent distal occlusion of rat middle cerebral arteries, we investigated whether there was a regional difference in receptor-mediated contractility of segments located upstream and downstream of the occlusion site. The contractile response to endothelin, angiotensin and 5-hydroxytryptamine...... receptor stimulation was studied by sensitive wire myograph. Results: Only downstream segments exhibited an augmented contractile response to stimulation with each of the three ligands, with the response towards sarafotoxin 6c being especially augmented compared to sham, upstream and contralateral controls...... occlusion without significant visible infarct resulted in locally increased ETB, angiotensin type 1 and 5-hydroxytryptamine 1B receptor-mediated contractile responses only in segments located downstream of the occlusion site. This suggests lack of wall stress as an initiating trigger leading to regulation...

  18. PRESSURE-RESISTANT VESSEL

    NARCIS (Netherlands)

    Beukers, A.; De Jong, T.

    1997-01-01

    Abstract of WO 9717570 (A1) The invention is directed to a wheel-shaped pressure-resistant vessel for gaseous, liquid or liquefied material having a substantially rigid shape, said vessel comprising a substantially continuous shell of a fiber-reinforced resin having a central opening, an inner

  19. Definition of at-risk occlusal surfaces of permanent molars--a descriptive study.

    Science.gov (United States)

    Muller-Bolla, Michèle; Courson, Frédéric; Droz, Dominique; Lupi-Pégurier, Laurence; Velly, Ana Miriam

    2009-01-01

    THE OBJECTIVE of this descriptive study was to define the at-risk occlusal surface to guide the practitioner in the decision of whether to seal or not. All dentists affiliated with the French Society of Pediatric Odontology (SFOP) and general practitioners (GP) registered in postgraduate courses in three French dental schools answered the same questionnaire illustrating four occlusal surfaces of permanent molars. It was focused on obtaining an optimal definition of an at-risk occlusal surface. The corresponding four molars were later sectioned to check the answers. Univariate logistic regression analyses and multivariate logistic regression models were tested to identify the factors associated with the at-risk occlusal surface. Eighty-six SFOP dentists and 136 GP filled in the form. Multivariate logistic regression models stratified by type of practice demonstrated that stained fissures (p =0.001) were only associated with at-risk occlusal surface among GP and the morphology of primary fissure (p=0.001) when considering SFOP dentists alone. The multivariate analyses demonstrated that stained fissures, and primary and secondary fissures were linked to the perception of an at-risk occlusal surface. An at-risk occlusal surface has narrow and deep primary fissures. Numerous secondary fissures could increase the risk. The coloration of fissures should not be used in the definition because it depends on tooth integrity.

  20. Containment vessel drain system

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Scott G.

    2018-01-30

    A system for draining a containment vessel may include a drain inlet located in a lower portion of the containment vessel. The containment vessel may be at least partially filled with a liquid, and the drain inlet may be located below a surface of the liquid. The system may further comprise an inlet located in an upper portion of the containment vessel. The inlet may be configured to insert pressurized gas into the containment vessel to form a pressurized region above the surface of the liquid, and the pressurized region may operate to apply a surface pressure that forces the liquid into the drain inlet. Additionally, a fluid separation device may be operatively connected to the drain inlet. The fluid separation device may be configured to separate the liquid from the pressurized gas that enters the drain inlet after the surface of the liquid falls below the drain inlet.

  1. PARACENTRAL ACUTE MIDDLE MACULOPATHY AND DEEP RETINAL CAPILLARY PLEXUS INFARCTION SECONDARY TO REPERFUSED CENTRAL RETINAL ARTERY OCCLUSION.

    Science.gov (United States)

    Iafe, Nicholas A; Onclinx, Tania; Tsui, Irena; Sarraf, David

    2017-01-01

    To report a case of reperfused central retinal artery occlusion causing a globular pattern of paracentral acute middle maculopathy with en face optical coherence tomography (OCT). Retrospective case report. Widefield fluorescein angiography, en face OCT, and OCT-angiography were performed. Retinal capillary plexus vessel density (mm) was measured using OCT-angiography analysis and was defined as total vessel length (mm) per area (mm). A 76-year-old female presented with decreased vision in the left eye for 1 day. Widefield fluorescein angiography revealed delayed venous filling in the early phase and selective arterial staining in the late phase. Spectral domain OCT demonstrated paracentral acute middle maculopathy. Optical coherence tomography-angiography showed an ischemic deep retinal capillary plexus that colocalized with a globular shaped hyper-reflective pattern identified with structural en face OCT. Quantitative vessel density analysis comparing the fellow eye to the affected eye at presentation demonstrated 43% reduction in the superficial capillary plexus vessel density and 33% reduction of the deep capillary plexus in the affected eye. At 2 months follow-up, the reduction of superficial capillary plexus vessel density improved to 33%, whereas the deep capillary plexus vessel density reduced further to 35% compared with the fellow eye. The authors report a case of reperfused central retinal artery occlusion leading to a globular shaped paracentral acute middle maculopathy lesion with en face OCT. Quantitative OCT-angiography vessel density analysis in the chronic phase revealed disproportionate reduction of deep capillary plexus vessel density. The globular pattern of paracentral acute middle maculopathy with en face OCT can be an important clue to the diagnosis of central retinal artery occlusion.

  2. Reconstruction-Based Digital Dental Occlusion of the Partially Edentulous Dentition.

    Science.gov (United States)

    Zhang, Jian; Xia, James J; Li, Jianfu; Zhou, Xiaobo

    2017-01-01

    Partially edentulous dentition presents a challenging problem for the surgical planning of digital dental occlusion in the field of craniomaxillofacial surgery because of the incorrect maxillomandibular distance caused by missing teeth. We propose an innovative approach called Dental Reconstruction with Symmetrical Teeth (DRST) to achieve accurate dental occlusion for the partially edentulous cases. In this DRST approach, the rigid transformation between two symmetrical teeth existing on the left and right dental model is estimated through probabilistic point registration by matching the two shapes. With the estimated transformation, the partially edentulous space can be virtually filled with the teeth in its symmetrical position. Dental alignment is performed by digital dental occlusion reestablishment algorithm with the reconstructed complete dental model. Satisfactory reconstruction and occlusion results are demonstrated with the synthetic and real partially edentulous models.

  3. A study of reactor vessel integrity assessment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Hoon [Korea Institute of Nuclear Safety, Taejon (Korea, Republic of); Kim, Jong Kyung; Shin, Chang Ho; Seo, Bo Kyun [Hanyang Univ., Seoul (Korea, Republic of)

    1999-02-15

    The fast neutron fluence at the Reactor Pressure Vessel(RPV) of KNGR designed for 60 years lifetime was calculated by full-scope Monte Carlo simulation for reactor vessel integrity assessment. KNGR core geometry was modeled on a three-dimensional representation of the one-sixteenth of the reactor in-vessel component. Each fuel assemblies were modeled explicitly, and each fuel pins were axially divided into 5 segments. The maximum flux of 4.3 x 10{sup 10} neutrons/cm{sup 2}. sec at the RPV was obtained by tallying neutrons crossing the beltline of inner surface of the RPV.

  4. [Clinical treatment of occlusion in implant therapy].

    Science.gov (United States)

    Nakamura, Kimio

    2008-01-01

    A firmly established theory on occlusion, even with natural teeth, has been all but absent throughout history. it is even more difficult to find and evidence-based concept of occlusion for the relatively new field of implantology. Since i harbored doubts on initial gnathological theories of occlusion decades ago, my work in treating occlusion in patients with temporomandibular arthrosis has brought me to the realization that the diagnosis and adjustment of the alignment or misalignment of the light guide tapping position ( LGTP ) and clenching position (CLP) in the stable condylar position are important focal points for clinical occlusion. I have therefore striven for the seamless incorporation of the prosthodontic techniques of maintaining, correcting, and restoring occlusion into my day to day clinical practice, which includes periodontal treatment and orthodontics. Implantology has now been added to this context, and i feel there is no need to take a drastically different approach to creating and adjusting implant occlusion. I will present actual case reports and post operative observations of patients who received implant therapy in our clinic.

  5. ATHENA model for 4 x 350 MW(t) HTGR plant side-by-side steel vessel prismatic core concept

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosek, R.G.

    1986-01-01

    ATHENA is a computer code being developed at the Idaho National Engineering Laboratory under US Department of Energy support. The code will provide advanced best-estimate predictive capability for a wide spectrum of applications. The code has capability for modeling independent hydrodynamic systems which can currently include water, helium, Freon-II, idealgas, lithium, or lithium-lead as fluids. ATHENA was modified to allow point reactor kinetics evaluations for two nuclear reactor cores. Capability for specifying gas circulators was added and representative homologous curves were added for a helium circulator. A full system model was developed for a High Temperature Gas Reactor modular concept with a full secondary system model. The code capability to model the complete system was demonstrated and a representative transient for a circulator coastdown without reactor scram was modeled and evaluated to the point of flow stagnation.

  6. Combining retinal nerve fiber layer thickness with individual retinal blood vessel locations allows modeling of central vision loss in glaucoma

    Science.gov (United States)

    Wang, Hui; Wang, Mengyu; Baniasadi, Neda; Jin, Qingying; Elze, Tobias

    2017-02-01

    Purpose: To assess whether modeling of central vision loss (CVL) due to glaucoma by optical coherence tomography (OCT) retinal nerve fiber (RNF) layer thickness (RNFLT) can be improved by including the location of the major inferior temporal retinal artery (ITA), a known correlate of individual RNF geometry. Methods: Pat- tern deviations of the two locations of the Humphrey 24-2 visual field (VF) known to be specifically vulnerable to glaucomatous CVL and OCT RNFLT on the corresponding circumpapillary sector around the optic nerve head within the radius of 1.73mm were retrospectively selected from 428 eyes of 428 patients of a large clinical glaucoma service. ITA was marked on the 1.73mm circle by a trained observer. Linear regression models were fitted with CVL as dependent variable and VF mean deviation (MD) plus either of (1) RNFLT, (2) ITA, and (3) their combination, respectively, as regressors. To assess CVL over all levels of glaucoma severity, the three models were compared to a null model containing only MD. A Baysian model comparison was performed with the Bayes Factor (BF) as measure of strength of evidence (BF20: strong evidence over null model). Results: Neither RNFLT (BF=0.9) nor ITA (BF=1.4) alone provided positive evidence over the null model, but their combination resulted in a model with strong evidence (BF=21.4). Conclusion: While the established circumpapillary RNFLT sector, based on population statistics, could not satisfactorily model CVL, the inclusion of a retinal parameter related to individual eye anatomy yielded a strong structure-function model.

  7. Reactor vessel lower head integrity

    Energy Technology Data Exchange (ETDEWEB)

    Rubin, A.M.

    1997-02-01

    On March 28, 1979, the Three Mile Island Unit 2 (TMI-2) nuclear power plant underwent a prolonged small break loss-of-coolant accident that resulted in severe damage to the reactor core. Post-accident examinations of the TMI-2 reactor core and lower plenum found that approximately 19,000 kg (19 metric tons) of molten material had relocated onto the lower head of the reactor vessel. Results of the OECD TMI-2 Vessel Investigation Project concluded that a localized hot spot of approximately 1 meter diameter had existed on the lower head. The maximum temperature on the inner surface of the reactor pressure vessel (RPV) in this region reached 1100{degrees}C and remained at that temperature for approximately 30 minutes before cooling occurred. Even under the combined loads of high temperature and high primary system pressure, the TMI-2 RPV did not fail. (i.e. The pressure varied from about 8.5 to 15 MPa during the four-hour period following the relocation of melt to the lower plenum.) Analyses of RPV failure under these conditions, using state-of-the-art computer codes, predicted that the RPV should have failed via local or global creep rupture. However, the vessel did not fail; and it has been hypothesized that rapid cooling of the debris and the vessel wall by water that was present in the lower plenum played an important role in maintaining RPV integrity during the accident. Although the exact mechanism(s) of how such cooling occurs is not known, it has been speculated that cooling in a small gap between the RPV wall and the crust, and/or in cracks within the debris itself, could result in sufficient cooling to maintain RPV integrity. Experimental data are needed to provide the basis to better understand these phenomena and improve models of RPV failure in severe accident codes.

  8. Giant cavernous carotid aneurysm with spontaneous ipsilateral ICA occlusion: Report of 2 cases and review of literature

    Directory of Open Access Journals (Sweden)

    Savitr BV Sastri

    2013-01-01

    Full Text Available Giant aneurysms of the cavernous carotid artery are rare entities which present predominantly with features of compression of the adjacent neural structures, most commonly the III, IV, VI and V cranial nerves. Historically, treatment options included occlusion of the feeding vessel, direct surgery on the aneurysm, bypass procedures and in recent times, the use of endovascular devices. While intramural thrombus formation is commonly seen in giant aneurysms, we present 2 cases of giant cavernous aneurysms which on evaluation were found to have spontaneous occlusion of the feeding internal carotid artery secondary to thrombus formation, and review the available literature regarding the same.

  9. Adaptive Self-Occlusion Behavior Recognition Based on pLSA

    Directory of Open Access Journals (Sweden)

    Hong-bin Tu

    2013-01-01

    Full Text Available Human action recognition is an important area of human action recognition research. Focusing on the problem of self-occlusion in the field of human action recognition, a new adaptive occlusion state behavior recognition approach was presented based on Markov random field and probabilistic Latent Semantic Analysis (pLSA. Firstly, the Markov random field was used to represent the occlusion relationship between human body parts in terms an occlusion state variable by phase space obtained. Then, we proposed a hierarchical area variety model. Finally, we use the topic model of pLSA to recognize the human behavior. Experiments were performed on the KTH, Weizmann, and Humaneva dataset to test and evaluate the proposed method. The compared experiment results showed that what the proposed method can achieve was more effective than the compared methods.

  10. Effects of NM-3 on lymphatic vessel density and vascular endothelial growth factor of colon cancer in orthotopic implantation model of a severe combined immune deficiency mice

    Directory of Open Access Journals (Sweden)

    Jin-Shui Zhu

    2010-12-01

    Full Text Available The molecular mechanisms involved colon cancer tumorigenesis and development of colon cancer remain unclear. The aim of this study is to explore the inhibitive effects of NM-3 on lymphatic vessel density and vascular endothelial growth factor of micrometastatic lesion of orthotopic implantated colon cancer in the severe combined immune deficiency (SCID nude mice. Human colon cancer SW1116 cells were orthotopically implantated into the colon of the nude mice. Twenty-eight SCID nude mice were randomly divided into four groups (7 mice for each group after one week feeding and then the nude mice were treated with carboplatin and NM-3 via intraperitoneal injection twice a week for 8 weeks. The mice were sacrificed after 8 weeks and the vascular endothelial growth factor-C (VEGF-C, VEGF-D, VEGF-R-3 and lymphatic vessel density (LVD were analyzed using immunohistochemistry staining assay. LVD in NM-3 treated mice was significantly lower than that of control (normal saline treated mice. The expression of VEGF-C, VEGF-D, and VEGF-R-3 and the expression of mRNA of VEGF-C, VEGF-D, and VEGF-R-3 in NM-3 treated mice were significantly lower than that of control mice. The NM-3 inhibited the growth of colon cancer in the SCID mice of orthotopic implantatation model, and this effect may be related to the inhibitive effects of NM-3 on the lymphangiogenesis and vascular endothelial growth factor in colon cancer. NM-3 and carboplatin played a synergistic role in inhibiting lymphangiogenesis of human colon cancer in SCID nude mice and the further investigation of molecular mechanisms involved in colon cancer metastasis will provide an important evidence for understanding of lymphangiogenesis of human colon cancer.

  11. 2013 Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  12. 2011 Passenger Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  13. 2011 Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  14. 2013 Passenger Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  15. 2013 Tanker Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  16. 2013 Cargo Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  17. High Performance Marine Vessels

    CERN Document Server

    Yun, Liang

    2012-01-01

    High Performance Marine Vessels (HPMVs) range from the Fast Ferries to the latest high speed Navy Craft, including competition power boats and hydroplanes, hydrofoils, hovercraft, catamarans and other multi-hull craft. High Performance Marine Vessels covers the main concepts of HPMVs and discusses historical background, design features, services that have been successful and not so successful, and some sample data of the range of HPMVs to date. Included is a comparison of all HPMVs craft and the differences between them and descriptions of performance (hydrodynamics and aerodynamics). Readers will find a comprehensive overview of the design, development and building of HPMVs. In summary, this book: Focuses on technology at the aero-marine interface Covers the full range of high performance marine vessel concepts Explains the historical development of various HPMVs Discusses ferries, racing and pleasure craft, as well as utility and military missions High Performance Marine Vessels is an ideal book for student...

  18. Cheboygan Vessel Base

    Data.gov (United States)

    Federal Laboratory Consortium — Cheboygan Vessel Base (CVB), located in Cheboygan, Michigan, is a field station of the USGS Great Lakes Science Center (GLSC). CVB was established by congressional...

  19. 2011 Cargo Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  20. 2011 Tanker Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  1. 2013 Fishing Vessel Density

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Automatic Identification Systems (AIS) are a navigation safety device that transmits and monitors the location and characteristics of many vessels in U.S. and...

  2. Coastal Logbook Survey (Vessels)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains catch (landed catch) and effort for fishing trips made by vessels that have been issued a Federal permit for the Gulf of Mexico reef fish,...

  3. Influence of occlusal contact area on cusp defection and stress distribution.

    Science.gov (United States)

    Costa, Anna Karina Figueiredo; Xavier, Thaty Aparecida; Paes-Junior, Tarcisio José Arruda; Andreatta-Filho, Oswaldo Daniel; Borges, Alexandre Luiz Souto

    2014-11-01

    The purpose of this study was to evaluate the effect of occlusal contact area for loading on the cuspal defection and stress distribution in a first premolar restored with a high elastic modulus restorative material. The Rhinoceros 4.0 software was used for modeling the three-dimensional geometries of dental and periodontal structures and the inlay restoration. Thus, two different models, intact and restored teeth with three occlusal contact areas, 0.1, 0.5 and 0.75 mm(2), on enamel at the occlusal surface of buccal and lingual cusps. Finite element analysis (FEA) was performed with the program ANSYS (Workbench 13.0), which generated a mesh with tetrahedral elements with greater refinement in the regions of interest, and was constrained at the bases of cortical and trabecular bone in all axis and loaded with 100 N normal to each contact area. To analysis of maximum principal stress, the smaller occlusal contact area showed greater compressive stress in region of load application for both the intact and inlay restored tooth. However, tensile stresses at the occlusal isthmus were similar for all three tested occlusal contact areas (60 MPa). To displacement of the cusps was higher for teeth with inlay (0.46-0.48 mm). For intact teeth, the smaller contact area showed greater displacement (0.10 mm). For teeth with inlays, the displacement of the cusps were similar in all types of occlusal area. Cuspal displacement was higher in the restored tooth when compared to the intact tooth, but there were no significant variations even with changes in the occlusal contact area. RELEVANCE CLINICAL: Occlusal contacts have a great influence on the positioning of teeth being able to maintain the position and stability of the mandible. Axial loads would be able to generate more uniform stress at the root presenting a greater concentration of load application in the point and the occlusal surface. Thus, is necessary to analyze the relationship between these occlusal contacts as dental

  4. Modeling of a Piezoelectric MEMS Micropump Dedicated to Insulin Delivery and Experimental Validation Using Integrated Pressure Sensors: Application to Partial Occlusion Management

    OpenAIRE

    Fournier, S; Chappel, E.

    2017-01-01

    A numerical model based on equivalent electrical networks has been built to simulate the dynamic behavior of a positive-displacement MEMS micropump dedicated to insulin delivery. This device comprises a reservoir in direct communication with the inlet check valve, a pumping membrane actuated by a piezo actuator, two integrated piezoresistive pressure sensors, an anti-free-flow check valve at the outlet, and finally a fluidic pathway up to the patient cannula. The pressure profiles delivered b...

  5. Pulmonary veno-occlusive disease.

    Science.gov (United States)

    Montani, David; Lau, Edmund M; Dorfmüller, Peter; Girerd, Barbara; Jaïs, Xavier; Savale, Laurent; Perros, Frederic; Nossent, Esther; Garcia, Gilles; Parent, Florence; Fadel, Elie; Soubrier, Florent; Sitbon, Olivier; Simonneau, Gérald; Humbert, Marc

    2016-05-01

    Pulmonary veno-occlusive disease (PVOD) is a rare form of pulmonary hypertension (PH) characterised by preferential remodelling of the pulmonary venules. In the current PH classification, PVOD and pulmonary capillary haemangiomatosis (PCH) are considered to be a common entity and represent varied expressions of the same disease. The recent discovery of biallelic mutations in the EIF2AK4 gene as the cause of heritable PVOD/PCH represents a major milestone in our understanding of the molecular pathogenesis of PVOD. Although PVOD and pulmonary arterial hypertension (PAH) share a similar clinical presentation, with features of severe precapillary PH, it is important to differentiate these two conditions as PVOD carries a worse prognosis and life-threatening pulmonary oedema may occur following the initiation of PAH therapy. An accurate diagnosis of PVOD based on noninvasive investigations is possible utilising oxygen parameters, low diffusing capacity for carbon monoxide and characteristic signs on high-resolution computed tomography of the chest. No evidence-based medical therapy exists for PVOD at present and lung transplantation remains the preferred definitive therapy for eligible patients. Copyright ©ERS 2016.

  6. Collateral Ventilation Quantification Using Xenon-Enhanced Dynamic Dual-Energy CT: Differences between Canine and Swine Models of Bronchial Occlusion.

    Science.gov (United States)

    Park, Eun-Ah; Goo, Jin Mo; Park, Sang Joon; Lee, Chang Hyun; Park, Chang Min

    2015-01-01

    The aim of this study was to evaluate whether the difference in the degree of collateral ventilation between canine and swine models of bronchial obstruction could be detected by using xenon-enhanced dynamic dual-energy CT. Eight mongrel dogs and six pigs underwent dynamic dual-energy scanning of 64-slice dual-source CT at 12-second interval for 2-minute wash-in period (60% xenon) and at 24-second interval for 3-minute wash-out period with segmental bronchus occluded. Ventilation parameters of magnitude (A value), maximal slope, velocity (K value), and time-to-peak (TTP) enhancement were calculated from dynamic xenon maps using exponential function of Kety model. A larger difference in A value between parenchyma was observed in pigs than in dogs (absolute difference, -33.0 ± 5.0 Hounsfield units [HU] vs. -2.8 ± 7.1 HU, p = 0.001; normalized percentage difference, -79.8 ± 1.8% vs. -5.4 ± 16.4%, p = 0.0007). Mean maximal slopes in both periods in the occluded parenchyma only decreased in pigs (all p Xenon-ventilation CT allows the quantification of collateral ventilation and detection of differences between canine and swine models of bronchial obstruction.

  7. In-vessel core debris retention through external flooding of the reactor pressure vessel. State-of-the-art report

    Energy Technology Data Exchange (ETDEWEB)

    Heel, A.M.J.M. van

    1995-07-01

    An overview of the state-of-the-art knowledge on the ex-vessel flooding accident management strategy for severe accidents in a NPP has been given. The feasibility has been discussed, as well as the in- and ex-vessel phenomena, which influence the structural integrity of the vessel. Finally, some computer codes with the ability to model the phenomena involved in ex-vessel flooding have been discussed. (orig./HP).

  8. Maximizing mandibular prosthesis stability utilizing linear occlusion, occlusal plane selection, and centric recording.

    Science.gov (United States)

    Williamson, Richard A; Williamson, Anne E; Bowley, John; Toothaker, Randy

    2004-03-01

    The stability of mandibular complete dentures may be improved by reducing the transverse forces on the denture base through linear (noninterceptive) occlusion, selecting an occlusal plane that reduces horizontal vectors of force at occlusal contact, and utilizing a central bearing intraoral gothic arch tracing to record jaw relations. This article is intended to acquaint the reader with one technique for providing stable complete denture prostheses using the aforementioned materials, devices, and procedures.

  9. Influence of Modelling Options in RELAP5/SCDAPSIM and MAAP4 Computer Codes on Core Melt Progression and Reactor Pressure Vessel Integrity

    Directory of Open Access Journals (Sweden)

    Siniša Šadek

    2010-01-01

    Full Text Available RELAP5/SCDAPSIM and MAAP4 are two widely used severe accident computer codes for the integral analysis of the core and the reactor pressure vessel behaviour following the core degradation. The objective of the paper is the comparison of code results obtained by application of different modelling options and the evaluation of influence of thermal hydraulic behaviour of the plant on core damage progression. The analysed transient was postulated station blackout in NPP Krško with a leakage from reactor coolant pump seals. Two groups of calculations were performed where each group had a different break area and, thus, a different leakage rate. Analyses have shown that MAAP4 results were more sensitive to varying thermal hydraulic conditions in the primary system. User-defined parameters had to be carefully selected when the MAAP4 model was developed, in contrast to the RELAP5/SCDAPSIM model where those parameters did not have any significant impact on final results.

  10. Application of Response Surface Methodology for Modeling of Postweld Heat Treatment Process in a Pressure Vessel Steel ASTM A516 Grade 70.

    Science.gov (United States)

    Peasura, Prachya

    2015-01-01

    This research studied the application of the response surface methodology (RSM) and central composite design (CCD) experiment in mathematical model and optimizes postweld heat treatment (PWHT). The material of study is a pressure vessel steel ASTM A516 grade 70 that is used for gas metal arc welding. PWHT parameters examined in this study included PWHT temperatures and time. The resulting materials were examined using CCD experiment and the RSM to determine the resulting material tensile strength test, observed with optical microscopy and scanning electron microscopy. The experimental results show that using a full quadratic model with the proposed mathematical model is YTS = -285.521 + 15.706X1 + 2.514X2 - 0.004X1(2) - 0.001X2(2) - 0.029X1X2. Tensile strength parameters of PWHT were optimized PWHT time of 5.00 hr and PWHT temperature of 645.75°C. The results show that the PWHT time is the dominant mechanism used to modify the tensile strength compared to the PWHT temperatures. This phenomenon could be explained by the fact that pearlite can contribute to higher tensile strength. Pearlite has an intensity, which results in increased material tensile strength. The research described here can be used as material data on PWHT parameters for an ASTM A516 grade 70 weld.

  11. Principles of occlusion in implant dentistry

    Directory of Open Access Journals (Sweden)

    Mahesh Verma

    2015-01-01

    Full Text Available Dental implants require different biomechanical considerations from natural teeth. Also, with one of the criteria for long-term implant success being “occlusion,” it becomes imperative for the clinician to be well versed with the different concepts when rehabilitating with an implant prosthesis. All endeavors must be made to reduce the overload and noxious forces on implants during mandibular movements. The occlusal rehabilitation schemes for implant-supported prostheses are derivatives of the occlusal scheme for natural dentition. The implant-protected occlusion (IPO scheme has been designed to ensure the longevity of both prosthesis and implant. The article reviews the concepts of IPO and their applicability in different clinical scenarios.

  12. [The occlusal curvature and masticatory function].

    Science.gov (United States)

    Okano, Kota

    2011-10-01

    This study examined the association between masticatory movement and occlusal curvature in dentate adults. Forty-six subjects (mean age : 25.0 years) with complete permanent dentition except for their third molars participated in this study. A mandibular cast mounted on the lower member of an articulator was fixed to a three-dimensional measuring gauge (QM-Measure 353). Approximate spheres were calculated from the measurements according to the Broadrick Occlusal Plane Analyser. Subjects were asked to chew raw carrot, cheese, fish paste, boiled beef and gummy candy prepared to the size of 10 x 10 x 20 mm. Three-dimensional chewing movements of the mandibular central incisor point were measured using a Gnatho-analyzer. The Pearson correlation coefficient and multiple regression analysis were used to test the relationship between the occlusal curvature and masticatory movement. Significant correlations were found between masticatory movement and occlusal curvature in dentate adults (p masticatory movements.

  13. BY FRUSTUM CONFINING VESSEL

    Directory of Open Access Journals (Sweden)

    Javad Khazaei

    2016-09-01

    Full Text Available Helical piles are environmentally friendly and economical deep foundations that, due to environmental considerations, are excellent additions to a variety of deep foundation alternatives available to the practitioner. Helical piles performance depends on soil properties, the pile geometry and soil-pile interaction. Helical piles can be a proper alternative in sensitive environmental sites if their bearing capacity is sufficient to support applied loads. The failure capacity of helical piles in this study was measured via an experimental research program that was carried out by Frustum Confining Vessel (FCV. FCV is a frustum chamber by approximately linear increase in vertical and lateral stresses along depth from top to bottom. Due to special geometry and applied bottom pressure, this apparatus is a proper choice to test small model piles which can simulate field stress conditions. Small scale helical piles are made with either single helix or more helixes and installed in fine grained sand with three various densities. Axial loading tests including compression and tension tests were performed to achieve pile ultimate capacity. The results indicate the helical piles behavior depends essentially on pile geometric characteristics, i.e. helix configuration and soil properties. According to the achievements, axial uplift capacity of helical model piles is about equal to usual steel model piles that have the helixes diameter. Helical pile compression bearing capacity is too sufficient to act as a medium pile, thus it can be substituted other piles in special geoenvironmental conditions. The bearing capacity also depends on spacing ratio, S/D, and helixes diameter.

  14. Finding the right RoPax vessel size and freight price. A coste and mode choice model

    Energy Technology Data Exchange (ETDEWEB)

    Morales Fusco, P.; Grau Sala, M.; Sauri Marchan, S.

    2016-07-01

    Motorways of the sea operated as RoPax services are natural competitors with only-road freight haulage transportation. Cost, time and quality perceived are the determinants that make transporters and shippers use one route or another. This research considers the role that shipping companies and their ship deployment and pricing strategy have in the equation, as incentives for modal shift from road to sea. A model of the ships and transporter costs is developed considering different business models for the transporter (accompanied versus unaccompanied cargo) followed with a discrete choice model that, once calibrated, allows to test the influence that variables such as frequency, ship size and commercial speed might play into the competitiveness of a shipping line. As a result, different pricing strategies for the shipping line are developed and the characteristics of the optimal shipping line for each of them are found, to either maximize the profit of the shipping company or the modal shift. (Author)

  15. Effect of glove occlusion on the skin barrier

    DEFF Research Database (Denmark)

    Tiedemann, Daniel; Clausen, Maja Lisa; John, Swen Malthe

    2016-01-01

    that the negative effect of occlusion in itself is limited, and that only extensive and long-term occlusion will cause barrier impairment. However, studies investigating combined effect of occlusion and exposure to soaps/detergents indicate that occlusion significantly enhances the skin barrier damage caused...... by detergents/soaps in a dose-response fashion....

  16. Collateral ventilation quantification using xenon-enhanced dynamic dual-energy CT: Differences between canine and swine models of bronchial occlusion

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Ah; Goo, Jin Mo; Park, Sang Joon; Lee, Chang Hyun; Park, Chng Min [Dept. of Radiology, Seoul National University College of Medicine and Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul (Korea, Republic of)

    2015-06-15

    The aim of this study was to evaluate whether the difference in the degree of collateral ventilation between canine and swine models of bronchial obstruction could be detected by using xenon-enhanced dynamic dual-energy CT. Eight mongrel dogs and six pigs underwent dynamic dual-energy scanning of 64-slice dual-source CT at 12-second interval for 2-minute wash-in period (60% xenon) and at 24-second interval for 3-minute wash-out period with segmental bronchus occluded. Ventilation parameters of magnitude (A value), maximal slope, velocity (K value), and time-to-peak (TTP) enhancement were calculated from dynamic xenon maps using exponential function of Kety model. A larger difference in A value between parenchyma was observed in pigs than in dogs (absolute difference, -33.0 +/- 5.0 Hounsfield units [HU] vs. -2.8 +/- 7.1 HU, p = 0.001; normalized percentage difference, -79.8 +/- 1.8% vs. -5.4 +/- 16.4%, p = 0.0007). Mean maximal slopes in both periods in the occluded parenchyma only decreased in pigs (all p < 0.05). K values of both periods were not different (p = 0.892) in dogs. However, a significant (p = 0.027) difference was found in pigs in the wash-in period. TTP was delayed in the occluded parenchyma in pigs (p = 0.013) but not in dogs (p = 0.892). Xenon-ventilation CT allows the quantification of collateral ventilation and detection of differences between canine and swine models of bronchial obstruction.

  17. [Acute occlusion after coronary angioplasty. Early management and late course].

    Science.gov (United States)

    Nunes, G L; Sousa, A G; Tanajura, L F; Cano, M N; Maldonado, G; Feres, F; Mattos, L A; Pinto, I M; Sousa, J E

    1993-06-01

    Assess the efficacy of the different strategies employed in the management of acute closure and verify the late prognosis of patients who develop this complication. From january 1987, through December 1990, 2315 consecutive patients underwent percutaneous transluminal coronary angioplasty (PTCA) in our Institution. We analyzed 100 patients who had had acute closure of the dilated vessel determining the total incidence of myocardial infarction and death, the effectiveness of the different treatment strategies and clinical and angiographic predictors of poor in-hospital outcome. Late follow-up was obtained in the hospital survivors. The incidence of acute myocardial infarction in the group of 100 patients was 57%; death occurred in 12% of the patients. Forty-one individuals were referred to emergency bypass surgery, 35 received clinical treatment and 24 underwent redilatation of the vessel. Those managed clinically had a higher incidence of myocardial infarction compared to the ones who underwent either redilatation or surgery (74.3% versus 50% and 48.8%). The in-hospital mortality rate was significantly higher in patients with left ventricular ejection fraction p > 0.05). Acute coronary occlusion is a serious complication of angioplasty and is associated with high rates of major complications (myocardial infarction, death). Low left ventricular ejection fraction and PTCA involving the left anterior descending are predictors of higher in-hospital mortality in patients with acute closure. Late outcome is less favourable in patients submitted to clinical treatment in the acute phase.

  18. Current possibilities in occlusal caries management

    Directory of Open Access Journals (Sweden)

    Hrvoje Jurić

    2013-11-01

    Full Text Available Dental caries is a multifactorial disease that affects most populations throughout the world and it is still the primary cause of oral pain and tooth loss. The occlusal surfaces of posterior teeth are the most vulnerable sites for dental caries due to their anatomy. Therefore, the aim of the following article is to summarize current knowledge on occlusal caries development and the possibilities of its prevention. Although the overall caries rate today has fallen for populations in industrialized countries, the rate of occlusal surface caries has not decreased. This may be explained with fact that topically applied fluorides and their mode of action prevent caries better on smooth than on occlusal surfaces. As we know, tooth decay of first permanent molars causes a great deal of different short and long term difficulties for patients. Therefore, there is a continuous need for implementation of programs for caries prevention in permanent teeth. Nowadays, we like to treat our patients by minimally invasive methods. A very important step in our effective preventive treatment is sealing pits and fissures as a cornerstone of