6,269 research outputs found
Evaluation of Posterolateral Fusion Mass at Lumbosacral Junction Using Standard AP and Ferguson Radiographs
Get PDFPurpose : To evaluate the reliance of standard AP radiograph and Ferguson radiograph in assessment of instrumented lumbosacral fusion mass with intraobserver an d intraobserver reproducibilities. Materials and Methods : Postoperative standard AP radiograph and Ferguson radiograph were used to evaluate the fusion mass at the lumbosacral region of 44 consecutive patients who underwent posterolateral L4-S1 or L5-S1 instrumented fusion with pedicle screws & autogenous iliac bone graft. Ferguson radiograph was performed with the x-ray beam oriented toward the cranial portion at 40° relative to the x-ray table. All observations were performed independently by three observers, blinded to the history, diagnosis, and patient identity. The fusion mass was graded as solid, pseudarthrosis or questionable. A second review was repeated at 2 weeks after index review. Interobserver and intraobserver reproducibilities were analyzed with Fleiss' method.
Results : Ferguson radiographs were more reliable than standard AP radiographs in detecting the fusion mass. Kappa values with the interobserver reproducibility were higher in Ferguson radi ographs than in the standard AP radiographs. Kappa values with the intraobserver reproducibility of all three ob servers were higher in Ferguson radiographs than in the standard AP radiographs. The questionable fusion masses in the standard AP radiographs were revealed solid or pseudarthrosis in Ferguson radiographs in 67%. Conclusion : Ferguson radiograph is a more reliable method than standard AP radi ograph in evaluation instrumented posterolateral fusion mass in lumbosacral region.ope
A role for amphiphysin in AP-1/clathrin coat formation
Get PDFTransport of cargo within the endocytic and secretory pathway is generally mediated by coated vesicles. Clathrin, in combination with different adaptor proteins, is the major coat protein for vesicle formation at the plasma membrane, endosomes, and the trans-Golgi network (TGN). Best characterized is the formation of clathrin coats for endocytosis at the plasma membrane involving the adaptor protein complex AP-2. Clathrin and AP-2 were shown to be at the centre of a complex interactome of proteins accessory to vesicle formation. Considerably less is known about the formation of clathrin coated carriers at the TGN and endosomes, where the adaptor protein complex AP-1 plays a major role.
In vitro studies showed the minimal requirements for association of AP-1 to liposomal membranes to be activated ARF1, phosphoinositides, and either sorting signals or unknown cytosolic factors. We have used a liposome floatation assay to identify cytosolic proteins collaborating with AP-1 at the membrane. Separation of proteins from bovine brain cytosol with several chromatographic methods yielded an active fraction containing amphiphysin 1, amphiphysin 2, and endophilin A1. All three proteins are expressed in brain and known to be involved in AP-2/clathrin coat formation. They consist of an N-terminal N-BAR (Bin, amphiphysin, Rvs) domain for dimerization and membrane binding and a C-terminal SH3 (Src homology 3) domain for interaction with dynamin and synaptojanin. Amphiphysin 1 and 2 in addition contain a middle domain with binding sites for adaptors and clathrin. It was proposed that amphiphysins and endophilin are targeted to membranes with high curvature, such as the neck of a forming vesicle, where they recruit dynamin and synaptojanin in preparation for vesicle fission and uncoating.
In this thesis, I bacterially expressed and purified all three proteins and tested them in the floatation assay for AP-1 membrane binding activity. Only amphiphysin 2 showed activity, both as a homodimer and as a heterodimer with amphiphysin 1. Activity depended on a motif that was shown to bind to AP-1, AP-2, and clathrin in GST pull-down experiments.
Endogenous amphiphysins in primary neurons, as well as transiently expressed in neuronal or fibroblast cell lines, co-localized with AP-1 at the TGN. In addition, when expressed at high levels in neuronal cells, amphiphysins aggregated and interfered dominantly with the TGN localization of AP-1. Both phenomena depended on the presence of the clathrin and adaptor interaction sequence in the amphiphysins. Furthermore, both amphiphysins could be cross-linked to AP-1 in vivo.
Our results indicate that amphiphysin 1 and 2 function not only in clathrin coated vesicle formation for endocytosis at the plasma membrane, but are also part of the machinery forming AP-1/clathrin coats at the TGN and endosomes. This suggests that the machineries for CCV formation with AP-1 and AP-2 at different locations in the cell share more components than previously anticipated
The Treatment of Ties in AP Correlation
No full textThe Kendall tau and AP correlation coefficients are very commonly use to compare two rankings over the same set of items. Even though Kendall tau was originally defined assuming that there are no ties in the rankings, two alternative versions were soon developed to account for ties in two different scenarios: measure the accuracy of an observer with respect to a true and objective ranking, and measure the agreement between two observers in the absence of a true ranking. These two variants prove useful in cases where ties are possible in either ranking, and may indeed result in very different scores. AP correlation was devised to incorporate a top-heaviness component into Kendall tau, penalizing more heavily if differences occur between items at the top of the rankings, making it a very compelling coefficient in Information Retrieval settings. However, the treatment of ties in AP correlation remains an open problem. In this paper we fill this gap, providing closed analytical formulations of AP correlation under the two scenarios of ties contemplated in Kendall tau. In addition,we developed an R package that implements these coefficients.Best Short Paper Accepted author manuscriptMultimedia ComputingWeb Information System
Determination of Tangent Vectors in Construction of Ferguson Interpolation Curves and Surfaces
No full textIn technical practice we often need to find an interpolation curve which must go through the given base points. A basis for the calculation of the piecewise interpolation curve is the Ferguson cubic curve, the final shape of which is significantly influenced by the magnitude and the direction of the tangent vectors at the startpoints and endpoints of the individual segments. This article describes a method for calculating tangent vectors at every definition point, which ensures a perfect adaptation of the shape of Ferguson cubic curves to the given configuration of the definition points. This method of determining tangent vectors shows minimal undesirable waving among given points, overshooting in the vicinity of given points is considerably limited, and first-degree continuity is ensured among individual parts of the Ferguson cubic curve. The results are used to create a mathematical model of the given surface. The mathematical model is formed by connecting the Ferguson 12 vector patches. A spherical surface was selected as the testing surface, because it is easy to judge the accuracy of the method by comparing the values of the coordinates of the points on the calculated interpolation surface with the exact analytically calculated values
Delamination Analysis of A Class of AP-PLY Composite Laminates
No full textA recently developed fiber placement architecture, AP-PLY, has been shown to give significantly improved damage tolerance characteristics of composite structures. The behavior of delaminations resulting from low speed impact damage is of particular concern. Major attention has been paid to expand current knowledge on the delamination response of simple AP-PLY composite structure and move towards in-depth understanding of the failure mechanisms behind the damage tolerance. This thesis presents the approaches to predict delamination onset and analyze delamination growth, in support of the search of the optimum woven pattern for AP-PLY composite laminates. The recovered interlaminar stress between layers combined with the maximum stress criterion determined the delamination onset of simple AP-PLY composite laminate under out-of-plane loads. 2D finite element models with cohesive elements inserted in the interfaces of woven layers have been built to evaluate the delamination initiation and propagation in the different woven patterns of simple AP-PLY composite beams. The parameters of the woven pattern, such as the woven angle, the number of woven plies, the number of straight filled plies, and the location of the woven patterns in through the thickness direction, were investigated and shown to have a significant effect on delamination creation and growth. An energy method based on beam theory was proposed to analyze the strain energy release rate (SERR) of an existing crack in an AP-PLY beam structure. The developed analytical method was implemented in isotropic materials and the obtained SERR of a crack was validated by reference results and finite element solutions. The general behavior of crack growth on the left or right crack tip was evaluated and basic trends leading to crack propagation on one side of the crack were established. A correction factor was introduced to improve the accuracy of the SERR of a small crack through the numerical calculation. The singularity of crack tip caused by dissimilar materials was investigated and was found that the inclusion of the singularity effect could increase the accuracy for small cracks. It has been shown that the neutral axis needs to be relocated to decouple the bending and membrane behavior of unsymmetrical composite laminates, thus to meet the requirement of minimizing the strain energy of the delaminated beam to calculate the SERR of a delaminated composite beam. The calculated SERR of a crack in a composite beam has been verified by comparing with a finite element model. The woven plies in AP-PLY composite laminate altered the layup and two conventional laminates with different stacking sequences were identified in an AP-PLY composite laminate based on the assumption that the resin areas were ignored. A step by step approach was developed to obtain the SERR of a crack that goes across different materials. The analytical SERR determined when two materials are used in sequence, sets the stage for optimization of AP-PLY composite laminates without taking account of the effect of the resin area. The procedure of optimization of simple AP-PLY pattern was proposed and industry may benefit for many applications. An equivalent stiffness approach was used to model regions containing resin pockets and straight or inclined composite layers. A series of three point bending tests was carried out where the failure process and loading capacity were evaluated. The methodology, procedure of optimization, philosophy outlined in this thesis might also be applied to the more complicated fully woven AP-PLY composite laminates. The work in this thesis contributes to the understanding of the behavior of AP-PLY composite laminates with delaminations
Recovery of renal function in liver transplant alone versus combined liver kidney transplantation: analysis from the NHSBT UK registry
Get PDFIntroduction and Aims: Recovery of renal function after liver transplantation is strongly influenced by pretransplant degree and duration of renal insufficiency, despite imprecise methods for measuring renal dysfunction. Indications for combined liver-kidney transplantation (CLKT) have been defined, but these are still under debate and hepatorenal syndrome (HRS) is a particularly challenging condition given the hardly predictable spontaneous improvement with liver transplant alone (LTA). Methods: We analysed data of 6035 patients (Jan 2001-Dec 2012) from NHSBT UK Transplant Registry. Renal function at 1 years after transplantation was compared between CLKT and LTA with stratification on the basis of glomerular filtration rate (eGFR) at transplant (KDIGO Guidelines) and treatment with renal replacement therapy (RRT). Renal function post-transplantation was classified as eGFR >60, between 59-30 and <30 ml/min/1.73m2, the latter identified as non recovery of renal function. Univariate and multivariable analysis were performed.
Results: 5912 patients (98.0%) underwent liver transplant alone (LTA) and 123 (2.0%) patients received a CLKT. 305 (5.2%) of the LTA group were on RRT at time of transplantation, compared to 72 (58.5%) of the CKLT group. No patient with a MELD score <20 received RRT before transplant. No patients with eGFR ≥60 mL/min/1.73m2 received CLKT. 27% of patients receiving CLKT were diagnosed with pre-transplant glomerular/tubular kidney disease, 39% with polycystic disease and 34% were not specified. LTA patients on RRT were more frequently presenting ascites ( p<0.001), variceal bleeding ( p=0.002), higher MELD score ( p<0.001), higher INR ( p<0.001) and bilirubin at transplant ( p<0.001), suggesting the occurrence of HRS (data not available). Patients on RRT experience a significant difference of renal function recovery at 1 year post-transplant when receiving LTA versus CLKT, with the latter group experiencing a higher percentage of non-recovery ( p=0.001; table 1). This difference was not detected for other eGFR stratifications.The univariate analysis identified recipient age >50 years, female gender, RRT in patients with MELD >20, polycystic disease and diabetes as predictive factors for non-recovery of renal function in patients undergoing LTA. In a multivariable model including all clinically relevant variables simultaneously, the independent predictors of renal function non-recovery were female gender (HR 2.76; 95% CI 1.52-4.99, p=0.001), RRT in patients with MELD >20 (HR 3.62; 95% CI 1.44-9.08, p=0.006) and diabetes (HR 2.55; 95% CI 1.38-4.73, p=0.003).
Conclusions: Recovery of renal function post-LTA is acceptable for patients with different stratifications of eGFR pre-transplant. RRT, female gender and diabetes may suggest to perform CLKT
Structure function analysis of blazars AP Librae and 3c279
No full textHighest Honors in AstronomyBlazars AP Librae and 3c279 are analyzed for microvariability using a technique known as structure function analysis. AP Librae was observed in April
of 2005 and 3c279 was observed in April of 2007. The data for AP Librae was
previously reduced by Andrew Collazzi and the author reduced the data for
3c279. Both sets of data were reduced using Robert Knop's data reduction
program.
The author ran structure function analysis on both sets of data. Structure function analysis is a statistical analysis run on data that is suppose to
nd timescales of variability, periodicity, and the noise type of data. Previous analysis of AP Librae confirmed mircrovariability, which also shows up in
the structure function of AP Librae. Blazar 3c279 was much quieter than AP
Librae and showed no microvariability durning any of the nights.College of Arts and ScienceDepartment of Physics and Astronom
AP-based wireless intrusion detection systems
No full textThis thesis was scanned from the print manuscript for digital preservation and is copyright the author.
Researchers can access this thesis by asking their local university, institution or public library to
make a request on their behalf. Monash staff and postgraduate students can use the link in the References field
Environmental toxicity, redox signaling and lung inflammation:the role of glutathione
Get PDFGlutathione (gamma-glutamyl-cysteinyl-glycine, GSH) is the most abundant intracellular antioxidant thiol and is central to redox defense during oxidative stress. GSH metabolism is tightly regulated and has been implicated in redox signaling and also in protection against environmental oxidant-mediated injury. Changes in the ratio of the reduced and disulfide form (GSH/GSSG) can affect signaling pathways that participate in a broad array of physiological responses from cell proliferation, autophagy and apoptosis to gene expression that involve H(2)O(2) as a second messenger. Oxidative stress due to oxidant/antioxidant imbalance and also due to environmental oxidants is an important component during inflammation and respiratory diseases such as chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, acute respiratory distress syndrome, and asthma. It is known to activate multiple stress kinase pathways and redox-sensitive transcription factors such as Nrf2, NF-kappaB and AP-1, which differentially regulate the genes for pro-inflammatory cytokines as well as the protective antioxidant genes. Understanding the regulatory mechanisms for the induction of antioxidants, such as GSH, versus pro-inflammatory mediators at sites of oxidant-directed injuries may allow for the development of novel therapies which will allow pharmacological manipulation of GSH synthesis during inflammation and oxidative injury. This article features the current knowledge about the role of GSH in redox signaling, GSH biosynthesis and particularly the regulation of transcription factor Nrf2 by GSH and downstream signaling during oxidative stress and inflammation in various pulmonary diseases. We also discussed the current therapeutic clinical trials using GSH and other thiol compounds, such as N-acetyl-l-cysteine, fudosteine, carbocysteine, erdosteine in environment-induced airways disease
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