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

PurposeThe role of endovascular graft oversizing on risk of distal graft migration following endovascular aneurysm repair for abdominal aortic aneurysm is poorly understood. A controlled in vitro investigation of the role of oversizing in graft-aorta attachment strength for endovascular grafts (EVGs) with barbs was performed.MethodsBarbed stent grafts (N = 20) with controlled graft oversizing varying from 4-45% were fabricated while maintaining other design variables unchanged. A flow loop with physiological flow characteristics and a biosynthetic aortic aneurysm phantom (synthetic aneurysm model with a bovine aortic neck) were developed. The stent grafts were deployed into the aortic neck of the bio-synthetic aortic aneurysm phantom under realistic flow conditions. Computed tomography imaging of the graft-aorta complex was used to document attachment characteristics such as graft apposition, number of barbs penetrated, and penetration depth and angle. The strength of graft attachment to the aortic neck was assessed using mechanical pullout testing. Stent grafts were categorized into four groups based on oversizing: 4-10%; 11-20%; 21-30%; and greater than 30% oversizing.ResultsPullout force, a measure of post-deployment fixation strength was not different between 4-10% (6.23 ± 1.90 N), 11-20% (6.25 ± 1.84 N) and 20-30% (5.85 ± 1.89 N) groups, but significantly lower for the group with greater than 30% oversizing (3.67 ± 1.41 N). Increasing oversizing caused a proportional decrease in the number of barbs penetrating the aortic wall (correlation = −0.83). Of the 14 barbs available in the stent graft, 89% of the barbs (12.5 of 14 on average) penetrated the aortic wall in the 4-10% oversizing group while only 38% (5.25 of 14) did for the greater than 30% group (P < .001). Also, the stent grafts with greater than 30% oversizing showed significantly poorer apposition characteristics such as eccentric compression or folding of the graft perimeter. The number and depth of barb penetration were found to be positively correlated to pullout force.ConclusionGreater than 30% graft oversizing affects both barb penetration and graft apposition adversely resulting in a low pullout force in this in vitro model. Barbed stent grafts with excessive oversizing are likely to result in poor fixation and increased risk of migration.Clinical RelevanceMigration of the endovascular grafts in abdominal aortic aneurysm (AAA) patients continues to be a cause of long-term complication in patients. This study is an assessment of the role of graft oversizing, a key variable chosen by the physician, on the fixation strength of these implants to the parent aorta. The findings suggest caution when choosing stent grafts that are excessively oversized

The function of Shp2 tyrosine phosphatase in the dispersal of acetylcholine receptor clusters

<p>Abstract</p> <p>Background</p> <p>A crucial event in the development of the vertebrate neuromuscular junction (NMJ) is the postsynaptic enrichment of muscle acetylcholine (ACh) receptors (AChRs). This process involves two distinct steps: the local clustering of AChRs at synapses, which depends on the activation of the muscle-specific receptor tyrosine kinase MuSK by neural agrin, and the global dispersal of aneural or "pre-patterned" AChR aggregates, which is triggered by ACh or by synaptogenic stimuli. We and others have previously shown that tyrosine phosphatases, such as the SH2 domain-containing phosphatase Shp2, regulate AChR cluster formation in muscle cells, and that tyrosine phosphatases also mediate the dispersal of pre-patterned AChR clusters by synaptogenic stimuli, although the specific phosphatases involved in this latter step remain unknown.</p> <p>Results</p> <p>Using an assay system that allows AChR cluster assembly and disassembly to be studied separately and quantitatively, we describe a previously unrecognized role of the tyrosine phosphatase Shp2 in AChR cluster disassembly. Shp2 was robustly expressed in embryonic Xenopus muscle in vivo and in cultured myotomal muscle cells, and treatment of the muscle cultures with an inhibitor of Shp2 (NSC-87877) blocked the dispersal of pre-patterned AChR clusters by synaptogenic stimuli. In contrast, over-expression in muscle cells of either wild-type or constitutively active Shp2 accelerated cluster dispersal. Significantly, forced expression in muscle of the Shp2-activator SIRPα1 (signal regulatory protein α1) also enhanced the disassembly of AChR clusters, whereas the expression of a truncated SIRPα1 mutant that suppresses Shp2 signaling inhibited cluster disassembly.</p> <p>Conclusion</p> <p>Our results suggest that Shp2 activation by synaptogenic stimuli, through signaling intermediates such as SIRPα1, promotes the dispersal of pre-patterned AChR clusters to facilitate the selective accumulation of AChRs at developing NMJs.</p

Liječenje površinskih rana štakora biljkom Anogeissus latifolia

Wound healing potential of etnanolic extract of Anogeissus latifolia bark (ALE) for treatment of dermal wounds in rats was studied on excision and incision wound models. HPTLC of the total extract was recorded for the purpose of standardization. Various parameters of incision wound, viz. epithelization period, scar area, tensile strength and hydroxyproline measurements along with wound contraction, were used to evaluate the effect of A. latifolia on wound healing. The results obtained indicate that A. latifolia accelerates the wound healing process by decreasing the surface area of the wound and increasing the tensile strength. Nitrofurazone ointment was used as a positive control. Complete epithelization was observed within 15 days with ALE. Measurements of the healed area and the hydroxyproline level were in agreement. Antibacterial activity of ALE was studied against Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) compared to erythromycin and tetracycline. Moderate activity was observed against all organisms. The present study provides a scientific rationale for the traditional use of Anogeissus latifolia in the management of skin diseases such as sores, boils and itching.Ispitivan je potencijal liječenja alkoholnog ekstrakta kore biljke Anogeissus latifolia (ALE) na površinskim ranama štakora. U svrhu standardizacije snimljen je HPTLC kromatogram ekstrakta. Da bi se odredio učinak na zacjeljivanje oljeda praćeni su različiti parametri: vrijeme potrebno za epitelizaciju, površina ožiljka, sila naprezanja, kontrakcija rane i određivanje hidroksiprolina. Dobiveni rezultati ukazuju da A. latifolia ubrzava proces zacjeljivanja rana jer smanjuje površinu rane i povećava silu naprezanja. Mast nitrofurazona je upotrebljena kao pozitivna kontrola. Unutar 15 dan primjene ekstrakta zapažena je potpuna epitelizacija rane. Mjerenja zacjeljene površine i količine hidroksiprolina bila su u skladu. Antibakterijsko djelovanje ALE proučavano je na Gram-pozitivnim (Staphylococcus aureus) i Gram-negativnim bakterijama (Escherichia coli, Pseudomonas aeruginosa i Klebsiella pneumoniae) i uspoređeno s djelovanjem eritromicina i tetraciklina. Primjećeno je umjereno djelovanje protiv svih ispitivanih bakterija. Istraživanja su pokazala znanstvenu opravdanost tradicionalne primjene biljke Anogeissus latifolia u liječenju različitih bolesti kože kao što su rane, gnojni čirevi i svrbež

Liječenje površinskih rana štakora biljkom Anogeissus latifolia

Wound healing potential of etnanolic extract of Anogeissus latifolia bark (ALE) for treatment of dermal wounds in rats was studied on excision and incision wound models. HPTLC of the total extract was recorded for the purpose of standardization. Various parameters of incision wound, viz. epithelization period, scar area, tensile strength and hydroxyproline measurements along with wound contraction, were used to evaluate the effect of A. latifolia on wound healing. The results obtained indicate that A. latifolia accelerates the wound healing process by decreasing the surface area of the wound and increasing the tensile strength. Nitrofurazone ointment was used as a positive control. Complete epithelization was observed within 15 days with ALE. Measurements of the healed area and the hydroxyproline level were in agreement. Antibacterial activity of ALE was studied against Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) compared to erythromycin and tetracycline. Moderate activity was observed against all organisms. The present study provides a scientific rationale for the traditional use of Anogeissus latifolia in the management of skin diseases such as sores, boils and itching.Ispitivan je potencijal liječenja alkoholnog ekstrakta kore biljke Anogeissus latifolia (ALE) na površinskim ranama štakora. U svrhu standardizacije snimljen je HPTLC kromatogram ekstrakta. Da bi se odredio učinak na zacjeljivanje oljeda praćeni su različiti parametri: vrijeme potrebno za epitelizaciju, površina ožiljka, sila naprezanja, kontrakcija rane i određivanje hidroksiprolina. Dobiveni rezultati ukazuju da A. latifolia ubrzava proces zacjeljivanja rana jer smanjuje površinu rane i povećava silu naprezanja. Mast nitrofurazona je upotrebljena kao pozitivna kontrola. Unutar 15 dan primjene ekstrakta zapažena je potpuna epitelizacija rane. Mjerenja zacjeljene površine i količine hidroksiprolina bila su u skladu. Antibakterijsko djelovanje ALE proučavano je na Gram-pozitivnim (Staphylococcus aureus) i Gram-negativnim bakterijama (Escherichia coli, Pseudomonas aeruginosa i Klebsiella pneumoniae) i uspoređeno s djelovanjem eritromicina i tetraciklina. Primjećeno je umjereno djelovanje protiv svih ispitivanih bakterija. Istraživanja su pokazala znanstvenu opravdanost tradicionalne primjene biljke Anogeissus latifolia u liječenju različitih bolesti kože kao što su rane, gnojni čirevi i svrbež

Web Site Metadata

The currently established formats for how a Web site can publish metadata about a site's pages, the robots.txt file and sitemaps, focus on how to provide information to crawlers about where to not go and where to go on a site. This is sufficient as input for crawlers, but does not allow Web sites to publish richer metadata about their site's structure, such as the navigational structure. This paper looks at the availability of Web site metadata on today's Web in terms of available information resources and quantitative aspects of their contents. Such an analysis of the available Web site metadata not only makes it easier to understand what data is available today; it also serves as the foundation for investigating what kind of information retrieval processes could be driven by that data, and what additional data could be provided by Web sites if they had richer data formats to publish metadata

Stratification of a population of intracranial aneurysms using blood flow metrics.

Indices of the intra-aneurysm hemodynamic environment have been proposed as potentially indicative of their longitudinal outcome. To be useful, the indices need to be used to stratify large study populations and tested against known outcomes. The first objective was to compile the diverse hemodynamic indices reported in the literature. Furthermore, as morphology is often the only patient-specific information available in large population studies, the second objective was to assess how the ranking of aneurysms in a population is affected by the use of steady flow simulation as an approximation to pulsatile flow simulation, even though the former is clearly non-physiological. Sixteen indices of aneurysmal hemodynamics reported in the literature were compiled and refined where needed. It was noted that, in the literature, these global indices of flow were always time-averaged over the cardiac cycle. Steady and pulsatile flow simulations were performed on a population of 198 patient-specific and 30 idealised aneurysm models. All proposed hemodynamic indices were estimated and compared between the two simulations. It was found that steady and pulsatile flow simulations had a strong linear dependence (r ≥ 0.99 for 14 indices; r ≥ 0.97 for 2 others) and rank the aneurysms in an almost identical fashion (ρ ≥ 0.99 for 14 indices; ρ ≥ 0.96 for other 2). When geometry is the only measured piece of information available, stratification of aneurysms based on hemodynamic indices reduces to being a physically grounded substitute for stratification of aneurysms based on morphology. Under such circumstances, steady flow simulations may be just as effective as pulsatile flow simulation for estimating most key indices currently reported in the literature

Ranking deep web text collections for scalable information extraction

Information extraction (IE) systems discover structured in-formation from natural language text, to enable much richer querying and data mining than possible directly over the unstructured text. Unfortunately, IE is generally a com-putationally expensive process, and hence improving its ef-ficiency, so that it scales over large volumes of text, is of critical importance. State-of-the-art approaches for scaling the IE process focus on one text collection at a time. These approaches prioritize the extraction effort by learning key-word queries to identify the “useful ” documents for the IE task at hand, namely, those that lead to the extraction of structured “tuples. ” These approaches, however, do not at-tempt to predict which text collections are useful for the IE task—and hence merit further processing—and which ones will not contribute any useful output—and hence should be ignored altogether, for efficiency. In this paper, we focus on an especially valuable family of text sources, the so-called deep web collections, whose (remote) contents are only ac-cessible via querying. Specifically, we introduce and study techniques for ranking deep web collections for an IE task, to prioritize the extraction effort by focusing on collections with substantial numbers of useful documents for the task. We study both (adaptations of) state-of-the-art resource se-lection strategies for distributed information retrieval, and IE-specific approaches. Our extensive experimental eval-uation over realistic deep web collections, and for several different IE tasks, shows the merits and limitations of the alternative families of approaches, and provides a roadmap for addressing this critically important building block for efficient, scalable information extraction. 1

Yotiao, a Novel Protein of Neuromuscular Junction and Brain That Interacts with Specific Splice Variants of NMDA Receptor Subunit NR1

The molecular machinery underlying neurotransmitter receptor immobilization at postsynaptic sites is poorly understood. The NMDA receptor subunit NR1 can form clusters in heterologous cells via a mechanism dependent on the alternatively spliced C1 exon cassette in its intracellular C-terminal tail, suggesting a functional interaction between NR1 and the cytoskeleton. The yeast two-hybrid screen was used here to identify yotiao, a novel coiled coil protein that interacts with NR1 in a C1 exon-dependent manner. Yotiao mRNA (11 kb) is present modestly in brain and abundantly in skeletal muscle and pancreas. On Western blots, yotiao appears as an approximately 230 kDa band that is present in cerebral cortex, hippocampus, and cerebellum. Biochemical studies reveal that yotiao fractionates with cytoskeleton-associated proteins and with the postsynaptic density. With regard to immunohistochemistry, two anti-yotiao antibodies display a somatodendritic staining pattern similar to each other and to the staining pattern of NR1. Yotiao was colocalized by double-label immunocytochemistry with NR1 in rat brain and could be coimmunoprecipitated with NR1 from heterologous cells. Thus yotiao is an NR1-binding protein potentially involved in cytoskeletal attachment of NMDA receptors. Consistent with a general involvement in postsynaptic structure, yotiao was also found to be specifically concentrated at the neuromuscular junction in skeletal muscle

Magnetic-field sensitive charge density wave orders in the superconducting phase of UTe2

The intense interest in triplet superconductivity partly stems from theoretical predictions of exotic excitations such as non-abelian Majorana modes, chiral supercurrents, and half-quantum vortices. However, fundamentally new, and unexpected states may emerge when triplet superconductivity appears in a strongly correlated system. In this work we use scanning tunneling microscopy to reveal an unusual charge density wave (CDW) order in the heavy fermion triplet superconductor, UTe2. Our high-resolution maps reveal a multi-component incommensurate CDW whose intensity get weaker with increasing field, eventually disappearing at the superconducting critical field, Hc2. To explain the origin and phenomenology of this unusual CDW, we construct a Ginzburg-Landau theory for a uniform triplet superconductor coexisting with three triplet pair density wave (PDW) states. This theory gives rise to daughter CDWs which would be sensitive to magnetic field due to their origin in a triplet PDW state, and naturally explains our data. Our discovery of a CDW sensitive to magnetic fields and strongly intertwined with superconductivity, provides important new information for understanding the order parameter of UTe2 and uncovers the possible existence of a new kind of triplet PDW order which has not been previously explored.Comment: 12 pages, 4 figure

Observation of a Smoothly Tunable Dirac Point in Ge(BixSb1−x)2Te4Ge(Bi_{x}Sb_{1-x})_{2}Te_{4}

State-of-the-art topological devices require the use topological surface states to drive electronic transport. In this study, we examine a tunable topological system, $Ge(Bi_{x}Sb_{1-x})_{2}Te_{4}$, for a range of 'x' values from 0 to 1, using a combination of Fourier Transform Scanning Tunneling Spectroscopy (FT-STS) and Angle-Resolved Photoemission Spectroscopy (ARPES). Our results show that the Dirac point shifts linearly with 'x', crossing the Fermi energy near x = 0.7. This novel observation of a smoothly tunable, isolated Dirac point crossing through the topological transport regime and having strong linear dependence with substitution can be critical for future topological spintronics applications.Comment: 18 Pages, 9 Figures, including Appendi