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  1. Article ; Online: Predicting improved protein conformations with a temporal deep recurrent neural network.

    Pfeiffenberger, Erik / Bates, Paul A

    PloS one

    2018  Volume 13, Issue 9, Page(s) e0202652

    Abstract: Accurate protein structure prediction from amino acid sequence is still an unsolved problem. The most reliable methods centre on template based modelling. However, the accuracy of these models entirely depends on the availability of experimentally ... ...

    Abstract Accurate protein structure prediction from amino acid sequence is still an unsolved problem. The most reliable methods centre on template based modelling. However, the accuracy of these models entirely depends on the availability of experimentally resolved homologous template structures. In order to generate more accurate models, extensive physics based molecular dynamics (MD) refinement simulations are performed to sample many different conformations to find improved conformational states. In this study, we propose a deep recurrent network model, called DeepTrajectory, that is able to identify these improved conformational states, with high precision, from a variety of different MD based sampling protocols. The proposed model learns the temporal patterns of features computed from MD trajectory data in order to classify whether each recorded simulation snapshot is an improved quality conformational state, decreased quality conformational state or whether there is no perceivable change in state with respect to the starting conformation. The model was trained and tested on 904 trajectories from 42 different protein systems with a cumulative number of more than 1.7 million snapshots. We show that our model outperforms other state of the art machine-learning algorithms that do not consider temporal dependencies. To our knowledge, DeepTrajectory is the first implementation of a time-dependent deep-learning protocol that is re-trainable and able to adapt to any new MD based sampling procedure, thereby demonstrating how a neural network can be used to learn the latter part of the protein folding funnel.
    MeSH term(s) Algorithms ; Amino Acid Sequence ; Deep Learning ; Molecular Dynamics Simulation ; Neural Networks, Computer ; Protein Conformation ; Protein Folding ; Sequence Analysis, Protein ; Software
    Language English
    Publishing date 2018-09-04
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2267670-3
    ISSN 1932-6203 ; 1932-6203
    ISSN (online) 1932-6203
    ISSN 1932-6203
    DOI 10.1371/journal.pone.0202652
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Refinement of protein-protein complexes in contact map space with metadynamics simulations.

    Pfeiffenberger, Erik / Bates, Paul A

    Proteins

    2018  Volume 87, Issue 1, Page(s) 12–22

    Abstract: Accurate protein-protein complex prediction, to atomic detail, is a challenging problem. For flexible docking cases, current state-of-the-art docking methods are limited in their ability to exhaustively search the high dimensionality of the problem space. ...

    Abstract Accurate protein-protein complex prediction, to atomic detail, is a challenging problem. For flexible docking cases, current state-of-the-art docking methods are limited in their ability to exhaustively search the high dimensionality of the problem space. In this study, to obtain more accurate models, an investigation into the local optimization of initial docked solutions is presented with respect to a reference crystal structure. We show how physics-based refinement of protein-protein complexes in contact map space (CMS), within a metadynamics protocol, can be performed. The method uses 5 times replicated 10 ns simulations for sampling and ranks the generated conformational snapshots with ZRANK to identify an ensemble of n snapshots for final model building. Furthermore, we investigated whether the reconstructed free energy surface (FES), or a combination of both FES and ZRANK, referred to as CS
    MeSH term(s) Adaptor Proteins, Signal Transducing/chemistry ; Adaptor Proteins, Signal Transducing/metabolism ; Computer Simulation ; Humans ; Kinesins/chemistry ; Kinesins/metabolism ; Models, Molecular ; Molecular Docking Simulation ; Multiprotein Complexes/chemistry ; Multiprotein Complexes/metabolism ; Nerve Tissue Proteins/chemistry ; Nerve Tissue Proteins/metabolism ; Protein Binding ; Protein Conformation ; Protein Interaction Domains and Motifs
    Chemical Substances ADAP1 protein, human ; Adaptor Proteins, Signal Transducing ; Multiprotein Complexes ; Nerve Tissue Proteins ; KIF13B protein, human (EC 3.6.1.-) ; Kinesins (EC 3.6.4.4)
    Language English
    Publishing date 2018-10-30
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 806683-8
    ISSN 1097-0134 ; 0887-3585
    ISSN (online) 1097-0134
    ISSN 0887-3585
    DOI 10.1002/prot.25612
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Predicting improved protein conformations with a temporal deep recurrent neural network.

    Erik Pfeiffenberger / Paul A Bates

    PLoS ONE, Vol 13, Iss 9, p e

    2018  Volume 0202652

    Abstract: Accurate protein structure prediction from amino acid sequence is still an unsolved problem. The most reliable methods centre on template based modelling. However, the accuracy of these models entirely depends on the availability of experimentally ... ...

    Abstract Accurate protein structure prediction from amino acid sequence is still an unsolved problem. The most reliable methods centre on template based modelling. However, the accuracy of these models entirely depends on the availability of experimentally resolved homologous template structures. In order to generate more accurate models, extensive physics based molecular dynamics (MD) refinement simulations are performed to sample many different conformations to find improved conformational states. In this study, we propose a deep recurrent network model, called DeepTrajectory, that is able to identify these improved conformational states, with high precision, from a variety of different MD based sampling protocols. The proposed model learns the temporal patterns of features computed from MD trajectory data in order to classify whether each recorded simulation snapshot is an improved quality conformational state, decreased quality conformational state or whether there is no perceivable change in state with respect to the starting conformation. The model was trained and tested on 904 trajectories from 42 different protein systems with a cumulative number of more than 1.7 million snapshots. We show that our model outperforms other state of the art machine-learning algorithms that do not consider temporal dependencies. To our knowledge, DeepTrajectory is the first implementation of a time-dependent deep-learning protocol that is re-trainable and able to adapt to any new MD based sampling procedure, thereby demonstrating how a neural network can be used to learn the latter part of the protein folding funnel.
    Keywords Medicine ; R ; Science ; Q
    Subject code 612
    Language English
    Publishing date 2018-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article: Scirrhous Hepatocellular Carcinoma: Systematic Review and Pooled Data Analysis of Clinical, Radiological, and Histopathological Features.

    Murtha-Lemekhova, Anastasia / Fuchs, Juri / Schulz, Erik / Sterkenburg, Anthe Suzan / Mayer, Philipp / Pfeiffenberger, Jan / Hoffmann, Katrin

    Journal of hepatocellular carcinoma

    2021  Volume 8, Page(s) 1269–1279

    Abstract: Background: Aberrant subtypes of hepatocellular carcinoma (HCC) account for 20-30% of all HCCs and habitually present a challenge in diagnosis and treatment. Scirrhous hepatocellular carcinoma (s-HCC) is often misdiagnosed as cholangiocarcinoma, ... ...

    Abstract Background: Aberrant subtypes of hepatocellular carcinoma (HCC) account for 20-30% of all HCCs and habitually present a challenge in diagnosis and treatment. Scirrhous hepatocellular carcinoma (s-HCC) is often misdiagnosed as cholangiocarcinoma, fibrolamellar hepatocellular carcinoma, or metastasis.
    Methods: Electronic databases (PubMed, Web of Knowledge, Google Scholar, Cochrane Library, and WHO International Clinical Trials Registry Platform) were searched for publications on scirrhous hepatocellular carcinoma without date or language restrictions. Quality assessment was performed using a tool proposed by Murad et al for case reports and series. For observational studies, MINORS quality assessment tool was used. This study was registered at PROSPERO (CRD42020212323).
    Results: S-HCC arises in patients with chronic hepatitis (hepatitis B in 60% and hepatitis C in 21%). S-HCC primarily affects men with a mean age of 55.8 years. Serum AFP is elevated above 20IU/mL in 66.7% of the patients. On ultrasound, s-HCC presents as hypoechoic or mosaic pattern lesions (47.6% each) and causes a retraction of the liver surface (70%) when near the capsule. Delayed enhancement of the tumor is evident in 87.0%. On MRI, 65.0% of s-HCCs show a target appearance. Histopathologic pattern is mostly irregular (97.6%). Lesions show a bulging appearance (100%), septae (85.6%) and a central scar (63.5%), and usually lack central necrosis (75%). Immunohistochemistry shows HepPar 1 positivity in 64.6%, CK7 in 40.7%, and EMA in 41.9%. The 5-year overall survival rate estimates 45.2% and 45.5% of the patients experience a recurrence after hepatectomy.
    Conclusion: S-HCC is a rare subtype of HCC primarily arising in hepatitis- or cirrhosis-afflicted livers and incorporates atypical radiological and histopathological HCC features. Despite lower recurrence rates, overall survival of patients with s-HCC is poorer than generally for HCC, underlining the need for individualized treatment. Patients with atypical lesions of the liver should be referred to tertiary hospitals for interdisciplinary assessment and treatment.
    Language English
    Publishing date 2021-10-22
    Publishing country New Zealand
    Document type Journal Article
    ZDB-ID 2780784-8
    ISSN 2253-5969
    ISSN 2253-5969
    DOI 10.2147/JHC.S328198
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: A machine learning approach for ranking clusters of docked protein-protein complexes by pairwise cluster comparison.

    Pfeiffenberger, Erik / Chaleil, Raphael A G / Moal, Iain H / Bates, Paul A

    Proteins

    2017  Volume 85, Issue 3, Page(s) 528–543

    Abstract: Reliable identification of near-native poses of docked protein-protein complexes is still an unsolved problem. The intrinsic heterogeneity of protein-protein interactions is challenging for traditional biophysical or knowledge based potentials and the ... ...

    Abstract Reliable identification of near-native poses of docked protein-protein complexes is still an unsolved problem. The intrinsic heterogeneity of protein-protein interactions is challenging for traditional biophysical or knowledge based potentials and the identification of many false positive binding sites is not unusual. Often, ranking protocols are based on initial clustering of docked poses followed by the application of an energy function to rank each cluster according to its lowest energy member. Here, we present an approach of cluster ranking based not only on one molecular descriptor (e.g., an energy function) but also employing a large number of descriptors that are integrated in a machine learning model, whereby, an extremely randomized tree classifier based on 109 molecular descriptors is trained. The protocol is based on first locally enriching clusters with additional poses, the clusters are then characterized using features describing the distribution of molecular descriptors within the cluster, which are combined into a pairwise cluster comparison model to discriminate near-native from incorrect clusters. The results show that our approach is able to identify clusters containing near-native protein-protein complexes. In addition, we present an analysis of the descriptors with respect to their power to discriminate near native from incorrect clusters and how data transformations and recursive feature elimination can improve the ranking performance. Proteins 2017; 85:528-543. © 2016 Wiley Periodicals, Inc.
    MeSH term(s) Benchmarking ; Binding Sites ; Cluster Analysis ; Computational Biology/methods ; Machine Learning ; Molecular Docking Simulation/methods ; Protein Binding ; Protein Conformation ; Protein Interaction Mapping ; Proteins/chemistry ; Research Design ; Software ; Structural Homology, Protein ; Thermodynamics
    Chemical Substances Proteins
    Language English
    Publishing date 2017-01-20
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 806683-8
    ISSN 1097-0134 ; 0887-3585
    ISSN (online) 1097-0134
    ISSN 0887-3585
    DOI 10.1002/prot.25218
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Optimization of a nonviral transfection system to evaluate Cox-2 controlled interleukin-4 expression for osteoarthritis gene therapy in vitro.

    Lang, Annemarie / Neuhaus, Johannes / Pfeiffenberger, Moritz / Schröder, Erik / Ponomarev, Igor / Weber, Yvonne / Gaber, Timo / Schmidt, Michael F G

    The journal of gene medicine

    2014  Volume 16, Issue 11-12, Page(s) 352–363

    Abstract: Background: Gene therapy appears to have the potential for achieving a long-term remedy for osteoarthritis (OA). However, there is a risk of adverse reactions, especially when using cytomegalovirus-controlled expression. To provide a safe application, ... ...

    Abstract Background: Gene therapy appears to have the potential for achieving a long-term remedy for osteoarthritis (OA). However, there is a risk of adverse reactions, especially when using cytomegalovirus-controlled expression. To provide a safe application, we focused on the expression of therapeutic cytokines [e.g. interleukin (IL)-4] in a disease-responsive manner by use of the previously cloned Cox-2 promoter as 'genetic switch'. In the present study, we report the functionality of a controlled gene therapeutic system in an equine osteoarthritic cell model.
    Methods: Different nonviral transfection reagents were tested for their efficiency on equine chondrocytes stimulated with equine IL-1β or lipopolysaccharide to create an inflammatory environment. To optimize the transfection, we successfully redesigned the vector by excluding the internal ribosomal entry site (IRES). The functionality of our Cox-2 promoter construct with respect to expressing IL-4 was proven at the mRNA and protein levels and the anti-inflammatory potential of IL-4 was confirmed by analyzing the expression of IL-1β, IL-6, IL-8, matrix metalloproteinase (MMP)-1, MMP-3 and tumor necrosis factor (TNF)-α using a quantitative polymerase chain reaction.
    Results: Nonviral transfection reagents yielded transfection rates from 21% to 44% with control vectors with and without IRES, respectively. Stimulation of equine chondrocytes resulted in a 20-fold increase of mRNA expression of IL-1β. Such exogenous stimulation of chondrocytes transfected with pNCox2-IL4 led to an increase of IL-4 mRNA expression, whereas expression of inflammatory mediators decreased. The timely link between these events confirms the anti-inflammatory potential of synthesized IL-4.
    Conclusions: We consider that this approach has significant potential for translation into a useful anti-inflammation therapy. Molecular tools such as the described therapeutic plasmid pave the way for a local-controlled, self-limiting gene therapy.
    MeSH term(s) Animals ; Cells, Cultured ; Chondrocytes/immunology ; Chondrocytes/metabolism ; Cyclooxygenase 2/genetics ; Down-Regulation ; Gene Expression ; Genetic Therapy ; Genetic Vectors ; Horses ; Humans ; Inflammation Mediators/metabolism ; Interleukin-1beta/metabolism ; Interleukin-4/biosynthesis ; Interleukin-4/genetics ; Lipopolysaccharides/pharmacology ; Osteoarthritis/genetics ; Osteoarthritis/therapy ; Promoter Regions, Genetic ; Transfection
    Chemical Substances Inflammation Mediators ; Interleukin-1beta ; Lipopolysaccharides ; Interleukin-4 (207137-56-2) ; Cyclooxygenase 2 (EC 1.14.99.1)
    Language English
    Publishing date 2014-11
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1458024-x
    ISSN 1521-2254 ; 1099-498X
    ISSN (online) 1521-2254
    ISSN 1099-498X
    DOI 10.1002/jgm.2812
    Database MEDical Literature Analysis and Retrieval System OnLINE

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