2,007 research outputs found

    Nucleotide sequence and genomic organization of an ophiovirus associated with lettuce big-vein disease

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    The complete nucleotide sequence of an ophiovirus associated with lettuce big-vein disease has been elucidated. The genome consisted of four RNA molecules of approximately 7ò8, 1ò7, 1ò5 and 1ò4 kb. Virus particles were shown to contain nearly equimolar amounts of RNA molecules of both polarities. The 5'- and 3'-terminal ends of the RNA molecules are largely, but not perfectly, complementary to each other. The virus genome contains seven open reading frames. Database searches with the putative viral products revealed homologies with the RNA-dependent RNA polymerases of rhabdoviruses and Ranunculus white mottle virus, and the capsid protein of Citrus psorosis virus. The gene encoding the viral polymerase appears to be located on the RNA segment 1, while the nucleocapsid protein is encoded by the RNA3. No significant sequence similarities were observed with other viral proteins. In spite of the morphological resemblance with species in the genus Tenuivirus, the ophioviruses appear not to be evolutionary closely related to this genus nor any other viral genus

    Sequence analysis and genomic organization of Aphid lethal paralysis virus: a new member of the family Dicistroviridae

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    The complete nucleotide sequence of the genomic RNA of an aphid-infecting virus, Aphid lethal paralysis virus (ALPV), has been determined. The genome is 9812 nt in length and contains two long open reading frames (ORFs), which are separated by an intergenic region of 163 nt. The first ORF (5' ORF) is preceded by an untranslated leader sequence of 506 nt, while an untranslated region of 571 nt follows the second ORF (3' ORF). The deduced amino acid sequences of the 5' ORF and 3' ORF products respectively showed similarity to the non-structural and structural proteins of members of the newly recognized genus Cripavirus (family Dicistroviridae). On the basis of the observed sequence similarities and identical genome organization, it is proposed that ALPV belongs to this genus. Phylogenetic analysis showed that ALPV is most closely related to Rhopalosiphum padi virus, and groups in a cluster with Drosophila C virus and Cricket paralysis virus, while the other members of this genus are more distantly related. Infectivity experiments showed that ALPV can not only infect aphid species but is also able to infect the whitefly Trialeurodes vaporariorum, extending its host range to another family of the order Hemipter

    Convergence of sparse variational inference in gaussian processes regression

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    Gaussian processes are distributions over functions that are versatile and mathematically convenient priors in Bayesian modelling. However, their use is often impeded for data with large numbers of observations, N, due to the cubic (in N) cost of matrix operations used in exact inference. Many solutions have been proposed that rely on M << N inducing variables to form an approximation at a cost of O(NM^2). While the computational cost appears linear in N, the true complexity depends on how M must scale with N to ensure a certain quality of the approximation. In this work, we investigate upper and lower bounds on how M needs to grow with N to ensure high quality approximations. We show that we can make the KL-divergence between the approximate model and the exact posterior arbitrarily small for a Gaussian-noise regression model with M<<N. Specifically, for the popular squared exponential kernel and D-dimensional Gaussian distributed covariates, M=O((log N)^D) suffice and a method with an overall computational cost of O(N(log N)^{2D}(\log\log N)^2) can be used to perform inference

    Overcoming mean-field approximations in recurrent Gaussian process models

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    We identify a new variational inference scheme for dynamical systems whose transition function is modelled by a Gaussian process. Inference in this setting has either employed computationally intensive MCMC methods, or relied on factorisations of the variational posterior. As we demonstrate in our experiments, the factorisation between latent system states and transition function can lead to a miscalibrated posterior and to learning unnecessarily large noise terms. We eliminate this factorisation by explicitly modelling the dependence between state trajectories and the Gaussian process posterior. Samples of the latent states can then be tractably generated by conditioning on this representation. The method we obtain (VCDT: variationally coupled dynamics and trajectories) gives better predictive performance and more calibrated estimates of the transition function, yet maintains the same time and space complexities as mean-field methods. Code is available at: g i t h u b . c o m / i a l o n g / G P t

    Actually Sparse Variational Gaussian Processes

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    Gaussian processes (GPs) are typically criticised for their unfavourable scaling in both computational and memory requirements. For large datasets, sparse GPs reduce these demands by conditioning on a small set of inducing variables designed to summarise the data. In practice however, for large datasets requiring many inducing variables, such as low-lengthscale spatial data, even sparse GPs can become computationally expensive, limited by the number of inducing variables one can use. In this work, we propose a new class of inter-domain variational GP, constructed by projecting a GP onto a set of compactly supported B-spline basis functions. The key benefit of our approach is that the compact support of the B-spline basis functions admits the use of sparse linear algebra to significantly speed up matrix operations and drastically reduce the memory footprint. This allows us to very efficiently model fast-varying spatial phenomena with tens of thousands of inducing variables, where previous approaches failed

    Identifying the determinants in the equatorial domain of Buchnera GroEL implicated in binding Potato Leafroll Virus

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    Luteoviruses avoid degradation in the hemolymph of their aphid vector by interacting with a GroEL homolog from the aphid's primary endosymbiotic bacterium (Buchnera sp.). Mutational analysis of GroEL from the primary endosymbiont of Myzus persicae (MpB GroEL) revealed that the amino acids mediating binding of Potato leafroll virus (PLRV; Luteoviridae) are located within residues 9 to 19 and 427 to 457 of the N-terminal and C-terminal regions, respectively, of the discontinuous equatorial domain. Virus overlay assays with a series of overlapping synthetic decameric peptides and their derivatives demonstrated that R13, K15, L17, and R18 of the N-terminal region and R441 and R445 of the C-terminal region of the equatorial domain of GroEL are critical for PLRV binding. Replacement of R441 and R445 by alanine in full-length MpB GroEL and in MpB GroEL deletion mutants reduced but did not abolish PLRV binding. Alanine substitution of either R13 or K15 eliminated the PLRV-binding capacity of the other and those of L17 and R18. In the predicted tertiary structure of GroEL, the determinants mediating virus binding are juxtaposed in the equatorial plain

    The VEGF-A inhibitor sFLT-1 improves renal function by reducing endothelial activation and inflammation in a mouse model of type 1 diabetes

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    Immunopathology of vascular and renal diseases and of organ and celltransplantatio

    Characteristics Predicting Short-Term and Long-Term Health-Related Quality of Life in Patients with Esophageal Cancer After Neoadjuvant Chemoradiotherapy and Esophagectomy

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    Background: Esophagectomy is associated with lasting effect on health-related quality of life (HRQOL). Patients desire detailed information on the expected impact of treatment on their postoperative HRQOL. The aim of the present study is to identify clinicopathological characteristics predictive for changes in short-term and long-term HRQOL after neoadjuvant chemoradiotherapy (nCRT) and surgery. Methods: HRQOL was measured using EORTC-QLQ-C30 and QLQ-OES24 questionnaires prior to nCRT, three, six, nine and twelve months postoperatively and at a minimum of six years postoperatively. Based on previous experience and available literature, several subgroups were predefined for different clinicopathological characteristics: baseline global HRQOL, WHO performance status, histology, tumor stage and tumor location. The primary endpoints of the present study were the change compared to baseline in the HRQOL dimensions physical functioning and eating problems. Secondary endpoints were global HRQOL, fatigue and emotional problems. Results:In total, 134 (76%) of 177 patients who received HRQOL questionnaires, responded at baseline. Patients who reported a high baseline global HRQOL had a more severe deterioration in eating problems (+14.5 to + 18.0), global HRQOL (-16.0 to -28.0) and fatigue (+10.5 to +14.9) up to six years postoperatively compared to patients who reported a low baseline global HRQOL. Patients who had stage 2 tumor (UICC 6th edition) had a more severe deterioration in eating problems (+14.6 to +19.0) and global HRQOL (-10.1 to -17.1) than patients who had stage 3 tumor. Conclusions: The results suggest that patients with locally advanced esophageal cancer in favorable condition at baseline decline more in terms of various HRQOL outcomes.</p

    Epidermal growth factor receptor as target for perioperative elimination of circulating colorectal cancer cells

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    Surgical resection of the tumor is the primary treatment of colorectal cancer patients. However, we previously demonstrated that abdominal surgery promotes the adherence of circulating tumor cells (CTC) in the liver and subsequent liver metastasis development. Importantly, preoperative treatment with specific tumor-targeting monoclonal antibodies (mAb) prevented surgery-induced liver metastasis development in rats. This study investigated whether the epidermal growth factor receptor (EGFR) represents a suitable target for preoperative antibody treatment of colorectal cancer patients undergoing surgery. The majority of patients with resectable colorectal liver metastases were shown to have EGFR + CTCs. Three different anti-EGFR mAbs (cetuximab, zalutumumab, and panitumumab) were equally efficient in the opsonization of tumor cell lines. Additionally, all three mAbs induced antibody-dependent cellular phagocytosis (ADCP) of tumor cells by macrophages at low antibody concentrations in vitro, independent of mutations in EGFR signaling pathways. The plasma of cetuximab-treated patients efficiently opsonized tumor cells ex vivo and induced phagocytosis. Furthermore, neither proliferation nor migration of epithelial cells was affected in vitro, supporting that wound healing will not be hampered by treatment with low anti-EGFR mAb concentrations. These data support the use of a low dose of anti-EGFR mAbs prior to resection of the tumor to eliminate CTCs without interfering with the healing of the anastomosis. Ultimately, this may reduce the risk of metastasis development, consequently improving long-term patient outcome significantly.Transplantation and autoimmunit
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