Vanderbilt University

About: Vanderbilt University is a education organization based out in Nashville, Tennessee, United States. It is known for research contribution in the topics: Population & Cancer. The organization has 45066 authors who have published 106528 publications receiving 5435039 citations. The organization is also known as: Vandy.

Recommendations on Angiographic Revascularization Grading Standards for Acute Ischemic Stroke A Consensus Statement

Abstract: See related article, p 2509 Intra-arterial therapy (IAT) for acute ischemic stroke (AIS) has dramatically evolved during the past decade to include aspiration and stent-retriever devices. Recent randomized controlled trials have demonstrated the superior revascularization efficacy of stent-retrievers compared with the first-generation Merci device.1,2 Additionally, the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution (DEFUSE) 2, the Mechanical Retrieval and Recanalization of Stroke Clots Using Embolectomy (MR RESCUE), and the Interventional Management of Stroke (IMS) III trials have confirmed the importance of early revascularization for achieving better clinical outcome.3–5 Despite these data, the current heterogeneity in cerebral angiographic revascularization grading (CARG) poses a major obstacle to further advances in stroke therapy. To date, several CARG scales have been used to measure the success of IAT.6–14 Even when the same scale is used in different studies, it is applied using varying operational criteria, which further confounds the interpretation of this key metric.10 The lack of a uniform grading approach limits comparison of revascularization rates across clinical trials and hinders the translation of promising, early phase angiographic results into proven, clinically effective treatments.6–14 For these reasons, it is critical that CARG scales be standardized and end points for successful revascularization be refined.6 This will lead to a greater understanding of the aspects of revascularization that are strongly predictive of clinical response. The optimal grading scale must demonstrate (1) a strong correlation with clinical outcome, (2) simplicity and feasibility of scale interpretation while ensuring characterization of relevant angiographic findings, and (3) high inter-rater reproducibility. To address these issues, a multidisciplinary panel of neurointerventionalists, neuroradiologists, and stroke neurologists with extensive experience in neuroimaging and IAT, convened at the “Consensus Meeting on Revascularization Grading Following Endovascular Therapy” with the goal …

Atom-by-atom structural and chemical analysis by annular dark-field electron microscopy

Abstract: An imaging technique able to resolve and identify all individual atoms in non-periodic solids would be a very useful tool for materials analysis. Annular dark-field (ADF) imaging in an aberration-corrected scanning transmission electron microscope optimized for low voltage operation allows such an analysis, as shown by Ondrej Krivanek and co-workers. The technique was used to examine a monolayer of boron nitride, in which it revealed individual atomic substitutions involving carbon and oxygen impurity atoms. Careful analysis of the data enables the construction of a detailed map of the atomic structure, with all the atoms of the four species resolved and identified. An imaging technique that could identify all the individual atoms, including defects, in a material would be a useful tool. Here an electron-microscopy approach to the problem, based on annular dark-field imaging, is described. A monolayer of boron nitride was studied, and three types of atomic substitution were identified. Careful analysis of the data enabled the construction of a detailed map of the atomic structure. Direct imaging and chemical identification of all the atoms in a material with unknown three-dimensional structure would constitute a very powerful general analysis tool. Transmission electron microscopy should in principle be able to fulfil this role, as many scientists including Feynman realized early on1. It images matter with electrons that scatter strongly from individual atoms and whose wavelengths are about 50 times smaller than an atom. Recently the technique has advanced greatly owing to the introduction of aberration-corrected optics2,3,4,5,6,7,8. However, neither electron microscopy nor any other experimental technique has yet been able to resolve and identify all the atoms in a non-periodic material consisting of several atomic species. Here we show that annular dark-field imaging in an aberration-corrected scanning transmission electron microscope optimized for low voltage operation can resolve and identify the chemical type of every atom in monolayer hexagonal boron nitride that contains substitutional defects. Three types of atomic substitutions were found and identified: carbon substituting for boron, carbon substituting for nitrogen, and oxygen substituting for nitrogen. The substitutions caused in-plane distortions in the boron nitride monolayer of about 0.1 A magnitude, which were directly resolved, and verified by density functional theory calculations. The results demonstrate that atom-by-atom structural and chemical analysis of all radiation-damage-resistant atoms present in, and on top of, ultra-thin sheets has now become possible.

Modulation of Apoptosis and Bcl-2 Expression by Prostaglandin E2 in Human Colon Cancer Cells

Abstract: Previously, we have shown that forced expression of prostaglandin endoperoxide synthase-2 [also called cyclooxygenase (COX) 2] leads to inhibition of programmed cell death in intestinal epithelial cells. More recently, we have demonstrated that growth of human colonic cancer xenografts is inhibited by treatment with a highly selective COX-2 inhibitor in tumors that express COX-2 (HCA-7) but not in those that lack COX-2 expression (HCT-116). To explore the biochemical mechanisms involved in these effects, we have evaluated the role of COX-2-derived eicosanoid products on programmed cell death in human colon cancer cells. Here we report that PGE2 treatment of human colon cancer cells leads to increased clonogenicity of HCA-7, but not HCT-116 cells. Treatment with a highly selective COX-2 inhibitor (SC-58125) decreases colony formation in monolayer culture and this growth inhibition was reversed by treatment with PGE2. Additionally, PGE2 inhibits programmed cell death caused by SC-58125 and induces Bcl-2 expression, but did not affect Bcl-x or Bax expression in human colon cancer (HCA-7) cells. Therefore, decreased cell death caused by PGE2 would enhance the tumorigenic potential of intestinal epithelial cells. Thus, these results may help to explain a component of the mechanism by which COX inhibitors prevent colorectal cancer in humans.