<p>Three-dimensional rotational angiography (3D-RA) is an established method within the field of interventional neuroradiology. The method has also a great potential in other areas with a complicated arterial anatomy. The purpose of this study was firstly to develop an investigative protocol for 3D-RA in renal transplanted patients with threatening allograft failure in diagnosing stenosis in the transplanted renal artery; secondly the protocol was evaluated and compared with a modified protocol including reduced contrast medium load. Furthermore, the advantages of the 3D reconstructions compared to the angiographic images were evaluated, likewise if an extended angle of rotation reduced the artifacts in the 3D reconstructions. The two protocols were compared with regard to image quality and acute nephrotoxicity. The accuracy of Doppler ultrasonography and the result of percutaneous transluminal angioplasty (PTA) were also assessed.</p><p>3D-RA was consecutively performed in 57 renal transplanted patients with suspicion of renal artery stenosis. A significant stenosis was found in 49% of the patients. The 3D reconstructions profiled 43% of the transplant renal artery stenoses better than the angiographic images. An extended angle of rotation reduced the artifacts. There was no statistical difference regarding image quality between the two protocols, and the renal function was equally affected in both protocols. Doppler ultrasonography sensitivity was 100%; specificity was 48% and positive predictive value 67%. PTA had a technical success rate of 92% and a clinical success rate of 75% after 3 months.</p><p>3D-RA is a helpful supplement in cases with complicated vascular anatomy, especially when PTA may be indicated. The 3D reconstructions profile the course of the artery more frequently than the angiographic images and support PTA. The 3D reconstructions are degraded of artifacts. Sampling artifacts can be diminished by increased C-arm rotation and increased number of projections. The distortions caused by beam hardening remain to be solved.</p>

<p>Renal artery stenosis (RAS) is a potentially curable cause of hypertension and azotemia. Besides intra-arterial renal angiography there are several non-invasive techniques utilized to diagnose patients with suspicion of renal artery stenosis. Removing the stenosis by revascularization to restore unobstructed blood flow to the kidney is known to improve and even cure hypertension/azotemia, but is associated with a significant complication rate. </p><p>To visualize renal arteries with x-ray techniques a contrast medium must be used. In a randomized, prospective study the complications of two types of contrast media (CO₂ and ioxaglate) were compared. CO₂ was not associated with acute nephropathy, but induced nausea and had lower attenuation differences compared to Ioxaglate. Acute nephropathy was related to the ioxaglate dose and the risk was evident even at very low doses if the patients were azotemic with creatinine clearance <40 ml/min. </p><p>Evaluating patients for clinically relevant renal artery stenosis can be done utilizing several non-invasive techniques. MRA was retrospectively evaluated and shown to be accurate in detecting hemodynamically significant RAS. In a prospective study of 58 patients, evaluated with four methods for renal artery stenosis, it was shown that MRA and CTA were significantly better than ultrasonography and captopril renography in detecting hemodynamically significant RAS. The standard of reference was trans-stenotic pressure gradient measurement, defining a stenosis as significant at a gradient of ≥15 mmHg. The discrepancies were mainly found in the presence of borderline stenosis.</p><p>The outcome of percutaneous revascularization procedures showed a technical success rate of 95%, clinical benefit in 63% of treated patients, 30-day mortality 1.5% and major complication rate of 13%. The major complication rate for patients with baseline serum creatinine >300µmol/l was 32%. Our results compare favorably with published studies and guidelines.</p>

The obstruction to the existence of Fredholm problems for elliptic differentail operators on manifolds with edges is a topological invariant of the operator. We give an explicit general formula for this invariant. As an application we compute this obstruction for geometric operators.

Three-dimensional rotational angiography (3D-RA) is an established method within the field of interventional neuroradiology. The method has also a great potential in other areas with a complicated arterial anatomy. The purpose of this study was firstly to develop an investigative protocol for 3D-RA in renal transplanted patients with threatening allograft failure in diagnosing stenosis in the transplanted renal artery; secondly the protocol was evaluated and compared with a modified protocol including reduced contrast medium load. Furthermore, the advantages of the 3D reconstructions compared to the angiographic images were evaluated, likewise if an extended angle of rotation reduced the artifacts in the 3D reconstructions. The two protocols were compared with regard to image quality and acute nephrotoxicity. The accuracy of Doppler ultrasonography and the result of percutaneous transluminal angioplasty (PTA) were also assessed. 3D-RA was consecutively performed in 57 renal transplanted patients with suspicion of renal artery stenosis. A significant stenosis was found in 49% of the patients. The 3D reconstructions profiled 43% of the transplant renal artery stenoses better than the angiographic images. An extended angle of rotation reduced the artifacts. There was no statistical difference regarding image quality between the two protocols, and the renal function was equally affected in both protocols. Doppler ultrasonography sensitivity was 100%; specificity was 48% and positive predictive value 67%. PTA had a technical success rate of 92% and a clinical success rate of 75% after 3 months. 3D-RA is a helpful supplement in cases with complicated vascular anatomy, especially when PTA may be indicated. The 3D reconstructions profile the course of the artery more frequently than the angiographic images and support PTA. The 3D reconstructions are degraded of artifacts. Sampling artifacts can be diminished by increased C-arm rotation and increased number of projections. The distortions caused by beam hardening remain to be solved.

Renal artery stenosis (RAS) is a potentially curable cause of hypertension and azotemia. Besides intra-arterial renal angiography there are several non-invasive techniques utilized to diagnose patients with suspicion of renal artery stenosis. Removing the stenosis by revascularization to restore unobstructed blood flow to the kidney is known to improve and even cure hypertension/azotemia, but is associated with a significant complication rate. To visualize renal arteries with x-ray techniques a contrast medium must be used. In a randomized, prospective study the complications of two types of contrast media (CO2 and ioxaglate) were compared. CO2 was not associated with acute nephropathy, but induced nausea and had lower attenuation differences compared to Ioxaglate. Acute nephropathy was related to the ioxaglate dose and the risk was evident even at very low doses if the patients were azotemic with creatinine clearance &lt;40 ml/min. Evaluating patients for clinically relevant renal artery stenosis can be done utilizing several non-invasive techniques. MRA was retrospectively evaluated and shown to be accurate in detecting hemodynamically significant RAS. In a prospective study of 58 patients, evaluated with four methods for renal artery stenosis, it was shown that MRA and CTA were significantly better than ultrasonography and captopril renography in detecting hemodynamically significant RAS. The standard of reference was trans-stenotic pressure gradient measurement, defining a stenosis as significant at a gradient of ≥15 mmHg. The discrepancies were mainly found in the presence of borderline stenosis. The outcome of percutaneous revascularization procedures showed a technical success rate of 95%, clinical benefit in 63% of treated patients, 30-day mortality 1.5% and major complication rate of 13%. The major complication rate for patients with baseline serum creatinine &gt;300µmol/l was 32%. Our results compare favorably with published studies and guidelines.

A la différence de l'urothélium de la vessie bien étudié, le phénotype et la fonction de l'urothélium intrarénal restent méconnus. L'objectif de ce travail est de caractériser l'urothélium intrarénal murin normal, au décours de lésions induites par une obstruction urétérale unilatérale, ou par ischémie/réperfusion avec ou sans insuffisance rénale aigue. Nos résultats suggèrent que l'urothélium intrarénal est différent de l'urothelium vésical et joue potentiellement un rôle clé dans les phénomènes de régénération rénale. Cet urothélium, remonte jusqu'au fornix au niveau de la zone cortico-médullaire et présente un phénotype de cellules progénitrices épithéliales. Cette structure est capable de s'adapter à l'hyperpression en modifiant son phénotype et devient pluristratifiée à l'instar de la vessie dans le but de reconstituer une barrière efficace. Après ischémie rénale unilatérale, ces cellules urothéliales constituent le premier contingent cellulaire qui prolifère, suivie par la régénération des cellules tubulaires de voisinage. Ces cellules urothéliales n'ont pas de propriété de migration à distance pour recoloniser les tubules lésés. Cette prolifération est médiée par la voie FGF7-FGFR2IIIb. L'inhibition de la prolifération des cellules urothéliales et tubulaires au cours d'une insuffisance rénale aiguë ischémique est expliquée par une inhibition de la transcription rénale de FGF7, et peut être prévenue par l'administration de FGF7. Le FGF7 pourrait ainsi être un traitement potentiel dans l'insuffisance rénale aigue : son administration précoce permet à la fois un rôle de néphroprotection (diminution de l'intensité des lésions) et accélère la régénération tubulaire

We introduce abortable and query-abortable object types intended for implementation in asynchronous shared-memory systems with low contention. Implementations of such types behave like ordinary objects when accessed sequentially, but may abort operations when accessed concurrently. An aborted operation may or may not take effect, i.e., cause a state transition, and it returns no indication of which possibility occurred. Since this uncertainty can be problematic, a query-abortable type supports a QUERY operation that each process can use to determine its last non-QUERY operation on the object that caused a state transition, and the response associated with this state transition. Our research is closely related to obstruction-free implementations (introduced by Herlihy, Luchangco and Moir) and responsive obstruction-free implementations (introduced by Attiya, Guerraoui and Kouznetsov). Like abortable and query-abortable types, these implementations may exhibit degraded behaviour in the face of contention. We show that abortable registers--registers strictly weaker than safe registers--can be used to obtain obstruction-free and responsive obstruction-free implementations for any type. We present universal constructions for abortable and query-abortable types that are novel and efficient in the number of registers used. Specifically, they are based on a simple timestamping mechanism for detecting concurrent executions, and, in systems with n processes, use only n abortable registers or only O(n^2) single-reader, single-writer abortable registers. The timestamping mechanism we introduce is based on the inc&read counter type and appears to be interesting in its own right. As a generalization, we study the k-inc&read counter types, for k>0. We also identify a potential problem with correctness properties based on step contention: with such properties, the composition of correct object implementations may result in an implementation that is not correct. In other words, implementations defined in terms of step contention are not always composable. To avoid this problem, we introduce a property based on interval contention, namely non-triviality, to define the correct behaviour of abortable and query-abortable object implementations.

We introduce abortable and query-abortable object types intended for implementation in asynchronous shared-memory systems with low contention. Implementations of such types behave like ordinary objects when accessed sequentially, but may abort operations when accessed concurrently. An aborted operation may or may not take effect, i.e., cause a state transition, and it returns no indication of which possibility occurred. Since this uncertainty can be problematic, a query-abortable type supports a QUERY operation that each process can use to determine its last non-QUERY operation on the object that caused a state transition, and the response associated with this state transition. Our research is closely related to obstruction-free implementations (introduced by Herlihy, Luchangco and Moir) and responsive obstruction-free implementations (introduced by Attiya, Guerraoui and Kouznetsov). Like abortable and query-abortable types, these implementations may exhibit degraded behaviour in the face of contention. We show that abortable registers--registers strictly weaker than safe registers--can be used to obtain obstruction-free and responsive obstruction-free implementations for any type. We present universal constructions for abortable and query-abortable types that are novel and efficient in the number of registers used. Specifically, they are based on a simple timestamping mechanism for detecting concurrent executions, and, in systems with n processes, use only n abortable registers or only O(n^2) single-reader, single-writer abortable registers. The timestamping mechanism we introduce is based on the inc&read counter type and appears to be interesting in its own right. As a generalization, we study the k-inc&read counter types, for k>0. We also identify a potential problem with correctness properties based on step contention: with such properties, the composition of correct object implementations may result in an implementation that is not correct. In other words, implementations defined in terms of step contention are not always composable. To avoid this problem, we introduce a property based on interval contention, namely non-triviality, to define the correct behaviour of abortable and query-abortable object implementations.

People who have better relationship and help each other in an organization will be helpful to an organization, because they will have higher sharing willingness. Knowledge is not like the tangible products that we¡¦ll lose them if we share them with other people. In contrast, we can enhance the value of knowledge by sharing. Because human resource strategy is relative to everyone in an organization, and knowledge-oriented culture and knowledge sharing obstructions will also effect the knowledge sharing willingness, this thesis focus on the relationship among human resource strategy, knowledge-oriented culture, knowledge sharing obstructions, and knowledge sharing willingness. I use inducement strategy, investment strategy, and involvement strategy addressed by Dyer & Holder (1988) as foundation to analyze the difference of these strategies in knowledge sharing willingness. And I use eight characteristics of knowledge-oriented culture addressed by Wu (2001) as a moderator between human resource strategies and knowledge sharing willingness. Moreover, I also summarize knowledge sharing obstructions from literature and use factor analysis to divide many obstructions into four types to understand the relationship between sharing obstructions and knowledge sharing willingness. The four types are obstruction of interaction and development, obstruction of resource providing, obstruction of self satisfaction, and obstruction of communication. The samples are employees and managers of human resource department. After statistic analyzing, the results are summarize as following: 1¡BIn human resource strategies, inducement strategy has more influence on knowledge sharing willingness than investment strategy. 2¡BIn knowledge-oriented culture, higher degree of professionalism and openness, initiative of learning, experience sharing, and relationship and harmony will help involvement strategy to cause higher knowledge sharing willingness. 3¡BIn knowledge sharing obstructions, obstructions of cooperation and development, resource providing, and self motivation will influence knowledge sharing willingness. And obstruction of self motivation has stronger influence. 4¡BHuman resource strategies and knowledge sharing obstructions a.Using inducement strategy will cause fewer obstructions of cooperation and development, resource providing, self motivation, and communication. b.Using investment strategy will cause fewer obstructions of cooperation and development and resource providing. 5¡BKnowledge sharing obstructions and the interaction of human resource strategies and personal and organizational characteristics a.When using involvement strategy, people with longer seniority will cause fewer obstructions of resource providing. b.When using inducement strategy, high-tech enterprises will cause higher obstruction of communication. c.When using involvement strategy, foreign enterprise and joint venture will cause higher obstruction of communication. According to the conclusion, this thesis proposes some ideas and recommendations to relative authorities and following researches.

Long segment tracheal obstruction is a potentially fatal condition arising from primary malignancy, congenital tracheal stenosis, or benign strictures. Shorter lesions are amenable to primary surgical repair, but anastomotic tension remains a limiting factor. Attention has therefore turned towards tissue engineered interposition grafts, consisting of cartilage, vascular, and airway epithelial cell layers. For clinical applications, it is essential to develop tools for noninvasive monitoring of in vivo graft development. This investigation therefore sough to optimize a tracheal patch and tube model suitable for SCID mouse implantation, and to demonstrate simultaneous tracking of human chondrocytes and epithelial cells labeled with contrasting intracellular magnetic resonance labels. Cartilage labeled with iron oxide nanoparticles was successfully distinguished from unlabeled control tissue both in vitro and in vivo. Gadolinium dendrimer labeling of adjacent airway epithelial cells, however, did not initially permit enhanced visualization. Further model optimization is required for simultaneous cell tracking.