1
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Harris CJ, Zhong Z, Ichino L, Feng S, Jacobsen SE. H1 restricts euchromatin-associated methylation pathways from heterochromatic encroachment. bioRxiv 2024:2023.05.10.539968. [PMID: 37214879 PMCID: PMC10197610 DOI: 10.1101/2023.05.10.539968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Silencing pathways prevent transposable element (TE) proliferation and help to maintain genome integrity through cell division. Silenced genomic regions can be classified as either euchromatic or heterochromatic, and are targeted by genetically separable epigenetic pathways. In plants, the RNA-directed DNA methylation (RdDM) pathway targets mostly euchromatic regions, while CMT DNA methyltransferases are mainly associated with heterochromatin. However, many epigenetic features - including DNA methylation patterning - are largely indistinguishable between these regions, so how the functional separation is maintained is unclear. The linker histone H1 is preferentially localized to heterochromatin and has been proposed to restrict RdDM from encroachment. To test this hypothesis, we followed RdDM genomic localization in an h1 mutant by performing ChIP-seq on the largest subunit, NRPE1, of the central RdDM polymerase, Pol V. Loss of H1 resulted in NRPE1 enrichment predominantly in heterochromatic TEs. Increased NRPE1 binding was associated with increased chromatin accessibility in h1 , suggesting that H1 restricts NRPE1 occupancy by compacting chromatin. However, RdDM occupancy did not impact H1 localization, demonstrating that H1 hierarchically restricts RdDM positioning. H1 mutants experience major symmetric (CG and CHG) DNA methylation gains, and by generating an h1/nrpe1 double mutant, we demonstrate these gains are largely independent of RdDM. However, loss of NRPE1 occupancy from a subset of euchromatic regions in h1 corresponded to loss of methylation in all sequence contexts, while at ectopically bound heterochromatic loci, NRPE1 deposition correlated with increased methylation specifically in the CHH context. Additionally, we found that H1 similarly restricts the occupancy of the methylation reader, SUVH1, and polycomb-mediated H3K27me3. Together, the results support a model whereby H1 helps maintain the exclusivity of heterochromatin by preventing encroachment from other competing pathways.
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2
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Harris CJ, Amtmann A, Ton J. Epigenetic processes in plant stress priming: Open questions and new approaches. Curr Opin Plant Biol 2023; 75:102432. [PMID: 37523900 DOI: 10.1016/j.pbi.2023.102432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 08/02/2023]
Abstract
Priming reflects the capacity of plants to memorise environmental stress experience and improve their response to recurring stress. Epigenetic modifications in DNA and associated histone proteins may carry short-term and long-term memory in the same plant or mediate transgenerational effects, but the evidence is still largely circumstantial. New experimental tools now enable scientists to perform targeted manipulations that either prevent or generate a particular epigenetic modification in a particular location of the genome. Such 'reverse epigenetics' approaches allow for the interrogation of causality between individual priming-induced modifications and their role for altering gene expression and plant performance under recurring stress. Furthermore, combining site-directed epigenetic manipulation with conditional and cell-type specific promoters creates novel opportunities to test and engineer spatiotemporal patterns of priming.
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Affiliation(s)
- C Jake Harris
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
| | - Anna Amtmann
- School of Molecular Biosciences, University of Glasgow, Glasgow, G128QQ, UK.
| | - Jurriaan Ton
- School of Biosciences, University of Sheffield, Sheffield, S10 2TN, UK
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3
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Zhang Q, Wang Z, Lu X, Yan H, Zhang H, He H, Bischof S, Harris CJ, Liu Q. DDT-RELATED PROTEIN4-IMITATION SWITCH alters nucleosome distribution to relieve transcriptional silencing in Arabidopsis. Plant Cell 2023:7174257. [PMID: 37208763 PMCID: PMC10396365 DOI: 10.1093/plcell/koad143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 04/26/2023] [Accepted: 04/27/2023] [Indexed: 05/21/2023]
Abstract
DNA methylation is a conserved epigenetic modification that is typically associated with silencing of transposable elements and promoter methylated genes. However, some DNA-methylated loci are protected from silencing, allowing transcriptional flexibility in response to environmental and developmental cues. Through a genetic screen in Arabidopsis (Arabidopsis thaliana), we uncovered an antagonistic relationship between the MICRORCHIDIA (MORC) protein and the IMITATION SWITCH (ISWI) complex in regulating the DNA-methylated SUPPRESSOR OF DRM1 DRM2 CMT3 (SDC) reporter. We demonstrate that components of the plant-specific ISWI complex, including CHROMATIN REMODELING PROTEIN11 (CHR11), CHR17, DDT-RELATED PROTEIN4 (DDR4), and DDR5, function to partially de-repress silenced genes and transposable elements (TEs), through their function in regulating nucleosome distribution. This action also requires the known transcriptional activator DNAJ proteins, providing a mechanistic link between nucleosome remodeling and transcriptional activation. Genome-wide studies revealed that DDR4 causes changes in nucleosome distribution at numerous loci, a subset of which is associated with changes in DNA methylation and/or transcription. Our work reveals a mechanism for balancing transcriptional flexibility and faithful silencing of DNA-methylated loci. As both ISWI and MORC family genes are widely distributed across plant and animal species, our findings may represent a conserved eukaryotic mechanism for fine-tuning gene expression under epigenetic regulation.
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Affiliation(s)
- Qiyan Zhang
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences, Peking University, 100871 Beijing, China
| | - Zejia Wang
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences, Peking University, 100871 Beijing, China
| | - Xinyue Lu
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences, Peking University, 100871 Beijing, China
| | - Huiru Yan
- Institute of Advanced Agricultural Science, Peking University, Weifang, China
| | - Huawei Zhang
- Institute of Advanced Agricultural Science, Peking University, Weifang, China
| | - Hang He
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences, Peking University, 100871 Beijing, China
| | - Sylvain Bischof
- Department of Plant and Microbial Biology and Zürich-Basel Plant Science Center, University of Zürich, Zollikerstrasse 107, 8008 Zürich, Switzerland
| | - C Jake Harris
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
| | - Qikun Liu
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences, Peking University, 100871 Beijing, China
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4
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Zhong Z, Xue Y, Harris CJ, Wang M, Li Z, Ke Y, Liu M, Zhou J, Jami-Alahmadi Y, Feng S, Wohlschlegel JA, Jacobsen SE. MORC proteins regulate transcription factor binding by mediating chromatin compaction in active chromatin regions. Genome Biol 2023; 24:96. [PMID: 37101218 PMCID: PMC10131428 DOI: 10.1186/s13059-023-02939-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 04/17/2023] [Indexed: 04/28/2023] Open
Abstract
BACKGROUND The microrchidia (MORC) proteins are a family of evolutionarily conserved GHKL-type ATPases involved in chromatin compaction and gene silencing. Arabidopsis MORC proteins act in the RNA-directed DNA methylation (RdDM) pathway, where they act as molecular tethers to ensure the efficient establishment of RdDM and de novo gene silencing. However, MORC proteins also have RdDM-independent functions although their underlying mechanisms are unknown. RESULTS In this study, we examine MORC binding regions where RdDM does not occur in order to shed light on the RdDM-independent functions of MORC proteins. We find that MORC proteins compact chromatin and reduce DNA accessibility to transcription factors, thereby repressing gene expression. We also find that MORC-mediated repression of gene expression is particularly important under conditions of stress. MORC-regulated transcription factors can in some cases regulate their own transcription, resulting in feedback loops. CONCLUSIONS Our findings provide insights into the molecular mechanisms of MORC-mediated chromatin compaction and transcription regulation.
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Affiliation(s)
- Zhenhui Zhong
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA
| | - Yan Xue
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA
- Shandong Laboratory of Advanced Agricultural Sciences at Weifang, Peking University Institute of Advanced Agricultural Sciences, Weifang, 261000, Shandong, China
| | - C Jake Harris
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
| | - Ming Wang
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA
| | - Zheng Li
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA
| | - Yunqing Ke
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA
| | - Mukun Liu
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA
| | - Jessica Zhou
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA
| | - Yasaman Jami-Alahmadi
- Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Suhua Feng
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA
- Eli & Edythe Broad Center of Regenerative Medicine & Stem Cell Research, University of California, Los Angeles, CA, 90095, USA
| | - James A Wohlschlegel
- Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Steven E Jacobsen
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA, 90095, USA.
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.
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5
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Wang Q, Xue Y, Zhang L, Zhong Z, Feng S, Wang C, Xiao L, Yang Z, Harris CJ, Wu Z, Zhai J, Yang M, Li S, Jacobsen SE, Du J. Mechanism of siRNA production by a plant Dicer-RNA complex in dicing-competent conformation. Science 2021; 374:1152-1157. [PMID: 34648373 PMCID: PMC8682726 DOI: 10.1126/science.abl4546] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In eukaryotes, small RNAs (sRNAs) play critical roles in multiple biological processes. Dicer endonucleases are a central part of sRNA biogenesis. In plants, DICER-LIKE PROTEIN 3 (DCL3) produces 24-nucleotide (nt) small interfering RNAs (siRNAs) that determine the specificity of the RNA-directed DNA methylation pathway. Here, we determined the structure of a DCL3–pre-siRNA complex in an active dicing-competent state. The 5′-phosphorylated A1 of the guide strand and the 1-nt 3′ overhang of the complementary strand are specifically recognized by a positively charged pocket and an aromatic cap, respectively. The 24-nt siRNA length dependence relies on the separation between the 5′-phosphorylated end of the guide RNA and dual cleavage sites formed by the paired ribonuclease III domains. These structural studies, complemented by functional data, provide insight into the dicing principle for Dicers in general.
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Affiliation(s)
- Qian Wang
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Science, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Yan Xue
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Laixing Zhang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Zhenhui Zhong
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Suhua Feng
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Changshi Wang
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Science, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Lifan Xiao
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Science, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Zhenlin Yang
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Science, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - C. Jake Harris
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
| | - Zhe Wu
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Science, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Jixian Zhai
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Science, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China
| | - Maojun Yang
- Ministry of Education Key Laboratory of Protein Science, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Sisi Li
- Department of Biochemistry and Molecular Biology, International Cancer Center, Shenzhen University Health Science Center, Shenzhen, 518060, China,Co-corresponding authors: Jiamu Du (); Steven E. Jacobsen (); Sisi Li ()
| | - Steven E. Jacobsen
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA.,Howard Hughes Medical Institute, University of California, Los Angeles, CA 90095,Co-corresponding authors: Jiamu Du (); Steven E. Jacobsen (); Sisi Li ()
| | - Jiamu Du
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Science, Department of Biology, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.,Co-corresponding authors: Jiamu Du (); Steven E. Jacobsen (); Sisi Li ()
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6
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Ichino L, Boone BA, Strauskulage L, Harris CJ, Kaur G, Gladstone MA, Tan M, Feng S, Jami-Alahmadi Y, Duttke SH, Wohlschlegel JA, Cheng X, Redding S, Jacobsen SE. MBD5 and MBD6 couple DNA methylation to gene silencing through the J-domain protein SILENZIO. Science 2021; 372:eabg6130. [PMID: 34083448 PMCID: PMC8639832 DOI: 10.1126/science.abg6130] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Accepted: 05/20/2021] [Indexed: 01/02/2023]
Abstract
DNA methylation is associated with transcriptional repression of eukaryotic genes and transposons, but the downstream mechanism of gene silencing is largely unknown. Here we describe two Arabidopsis methyl-CpG binding domain proteins, MBD5 and MBD6, that are recruited to chromatin by recognition of CG methylation, and redundantly repress a subset of genes and transposons without affecting DNA methylation levels. These methyl-readers recruit a J-domain protein, SILENZIO, that acts as a transcriptional repressor in loss-of-function and gain-of-function experiments. J-domain proteins often serve as co-chaperones with HSP70s. Indeed, we found that SILENZIO's conserved J-domain motif was required for its interaction with HSP70s and for its silencing function. These results uncover an unprecedented role of a molecular chaperone J-domain protein in gene silencing downstream of DNA methylation.
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Affiliation(s)
- Lucia Ichino
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Brandon A Boone
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Luke Strauskulage
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94143, USA
- Tetrad Graduate Program, University of California San Francisco, San Francisco, CA 94143, USA
| | - C Jake Harris
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Gundeep Kaur
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Matthew A Gladstone
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Maverick Tan
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Suhua Feng
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edyth Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Yasaman Jami-Alahmadi
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Sascha H Duttke
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
| | - James A Wohlschlegel
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Xiaodong Cheng
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sy Redding
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94143, USA
| | - Steven E Jacobsen
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA.
- Department of Molecular, Cell and Developmental Biology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edyth Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Howard Hughes Medical Institute (HHMI), UCLA, Los Angeles, CA 90095, USA
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7
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Liu Q, Bischof S, Harris CJ, Zhong Z, Zhan L, Nguyen C, Rashoff A, Barshop WD, Sun F, Feng S, Potok M, Gallego-Bartolome J, Zhai J, Wohlschlegel JA, Carey MF, Long JA, Jacobsen SE. The characterization of Mediator 12 and 13 as conditional positive gene regulators in Arabidopsis. Nat Commun 2020; 11:2798. [PMID: 32493925 PMCID: PMC7271234 DOI: 10.1038/s41467-020-16651-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 05/14/2020] [Indexed: 12/18/2022] Open
Abstract
Mediator 12 (MED12) and MED13 are components of the Mediator multi-protein complex, that facilitates the initial steps of gene transcription. Here, in an Arabidopsis mutant screen, we identify MED12 and MED13 as positive gene regulators, both of which contribute broadly to morc1 de-repressed gene expression. Both MED12 and MED13 are preferentially required for the expression of genes depleted in active chromatin marks, a chromatin signature shared with morc1 re-activated loci. We further discover that MED12 tends to interact with genes that are responsive to environmental stimuli, including light and radiation. We demonstrate that light-induced transient gene expression depends on MED12, and is accompanied by a concomitant increase in MED12 enrichment during induction. In contrast, the steady-state expression level of these genes show little dependence on MED12, suggesting that MED12 is primarily required to aid the expression of genes in transition from less-active to more active states. Mediator is a multiprotein complex required to activate gene transcription by RNAPII. Here, the authors report that MED12 and MED13 are conditional positive regulators that facilitate the expression of genes depleted in active chromatin marks and the induction of gene expression in response to environmental stimuli in Arabidopsis.
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Affiliation(s)
- Qikun Liu
- School of Advanced Agricultural Sciences, Peking University, 100871, Beijing, China. .,Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA, 90095, USA.
| | - Sylvain Bischof
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA, 90095, USA.,Department of Plant and Microbial Biology and Zurich-Basel Plant Science Center, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland
| | - C Jake Harris
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Zhenhui Zhong
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA, 90095, USA.,Basic Forestry and Proteomics Center, Fujian Agriculture and Forestry University, 350002, Fuzhou, China
| | - Lingyu Zhan
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Calvin Nguyen
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Andrew Rashoff
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - William D Barshop
- Department of Biological Chemistry, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Fei Sun
- Department of Biological Chemistry, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Suhua Feng
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Magdalena Potok
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Javier Gallego-Bartolome
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Jixian Zhai
- Institute of Plant and Food Science, Department of Biology, Southern University of Science and Technology, Shenzhen, China
| | - James A Wohlschlegel
- Department of Biological Chemistry, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Michael F Carey
- Department of Biological Chemistry, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Jeffrey A Long
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Steven E Jacobsen
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA, 90095, USA. .,Howard Hughes Medical Institute, University of California at Los Angeles, Los Angeles, CA, 90095, USA.
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8
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Harris CJ, Scheibe M, Wongpalee SP, Liu W, Cornett EM, Vaughan RM, Li X, Chen W, Xue Y, Zhong Z, Yen L, Barshop WD, Rayatpisheh S, Gallego-Bartolome J, Groth M, Wang Z, Wohlschlegel JA, Du J, Rothbart SB, Butter F, Jacobsen SE. A DNA methylation reader complex that enhances gene transcription. Science 2019; 362:1182-1186. [PMID: 30523112 DOI: 10.1126/science.aar7854] [Citation(s) in RCA: 150] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Revised: 09/07/2018] [Accepted: 10/31/2018] [Indexed: 12/14/2022]
Abstract
DNA methylation generally functions as a repressive transcriptional signal, but it is also known to activate gene expression. In either case, the downstream factors remain largely unknown. By using comparative interactomics, we isolated proteins in Arabidopsis thaliana that associate with methylated DNA. Two SU(VAR)3-9 homologs, the transcriptional antisilencing factor SUVH1, and SUVH3, were among the methyl reader candidates. SUVH1 and SUVH3 bound methylated DNA in vitro, were associated with euchromatic methylation in vivo, and formed a complex with two DNAJ domain-containing homologs, DNAJ1 and DNAJ2. Ectopic recruitment of DNAJ1 enhanced gene transcription in plants, yeast, and mammals. Thus, the SUVH proteins bind to methylated DNA and recruit the DNAJ proteins to enhance proximal gene expression, thereby counteracting the repressive effects of transposon insertion near genes.
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Affiliation(s)
- C Jake Harris
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Marion Scheibe
- Quantitative Proteomics, Institute of Molecular Biology, 55128 Mainz, Germany
| | - Somsakul Pop Wongpalee
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Wanlu Liu
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Evan M Cornett
- Center for Epigenetics, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - Robert M Vaughan
- Center for Epigenetics, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - Xueqin Li
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Wei Chen
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Yan Xue
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Zhenhui Zhong
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA.,State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, 350002 Fuzhou, China
| | - Linda Yen
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - William D Barshop
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Shima Rayatpisheh
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Javier Gallego-Bartolome
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Martin Groth
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Zonghua Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, 350002 Fuzhou, China.,Institute of Oceanography, Minjiang University, 350108 Fuzhou, China
| | - James A Wohlschlegel
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jiamu Du
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Center for Plant Stress Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201602, China
| | - Scott B Rothbart
- Center for Epigenetics, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - Falk Butter
- Quantitative Proteomics, Institute of Molecular Biology, 55128 Mainz, Germany.
| | - Steven E Jacobsen
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, CA 90095, USA. .,Howard Hughes Medical Institute, University of California at Los Angeles, Los Angeles, CA, USA
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9
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Harris CJ, Baulcombe DC, Molnar A. Improved Denaturation of Small RNA Duplexes and Its Application for Northern Blotting. Methods Mol Biol 2017; 1580:1-6. [PMID: 28439822 DOI: 10.1007/978-1-4939-6866-4_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Small RNAs (sRNAs) are short (18-30 nucleotide) noncoding RNA molecules, which control gene expression and pathogen response in eukaryotes. They are associated with and guide nucleases to target nucleic acids by nucleotide base pairing. We found that current techniques for small RNA detection are adversely affected by the presence of complementary RNA. Thus we established FDF-PAGE (fully denaturing formaldehyde polyacrylamide gel electrophoresis), which dramatically improves denaturation efficiency and subsequently the detection of sequestered sRNAs.
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Affiliation(s)
- C Jake Harris
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - David C Baulcombe
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Attila Molnar
- School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
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10
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Harris CJ, Husmann D, Liu W, Kasmi FE, Wang H, Papikian A, Pastor WA, Moissiard G, Vashisht AA, Dangl JL, Wohlschlegel JA, Jacobsen SE. Arabidopsis AtMORC4 and AtMORC7 Form Nuclear Bodies and Repress a Large Number of Protein-Coding Genes. PLoS Genet 2016; 12:e1005998. [PMID: 27171361 PMCID: PMC4865129 DOI: 10.1371/journal.pgen.1005998] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 03/30/2016] [Indexed: 12/30/2022] Open
Abstract
The MORC family of GHKL ATPases are an enigmatic class of proteins with diverse chromatin related functions. In Arabidopsis, AtMORC1, AtMORC2, and AtMORC6 act together in heterodimeric complexes to mediate transcriptional silencing of methylated DNA elements. Here, we studied Arabidopsis AtMORC4 and AtMORC7. We found that, in contrast to AtMORC1,2,6, they act to suppress a wide set of non-methylated protein-coding genes that are enriched for those involved in pathogen response. Furthermore, atmorc4 atmorc7 double mutants show a pathogen response phenotype. We found that AtMORC4 and AtMORC7 form homomeric complexes in vivo and are concentrated in discrete nuclear bodies adjacent to chromocenters. Analysis of an atmorc1,2,4,5,6,7 hextuple mutant demonstrates that transcriptional de-repression is largely uncoupled from changes in DNA methylation in plants devoid of MORC function. However, we also uncover a requirement for MORC in both DNA methylation and silencing at a small but distinct subset of RNA-directed DNA methylation target loci. These regions are characterized by poised transcriptional potential and a low density of sites for symmetric cytosine methylation. These results provide insight into the biological function of MORC proteins in higher eukaryotes.
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Affiliation(s)
- C. Jake Harris
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, California, United States of America
| | - Dylan Husmann
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, California, United States of America
| | - Wanlu Liu
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, California, United States of America
| | - Farid El Kasmi
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Haifeng Wang
- Basic Forestry and Proteomics Research Center, Haixia Institute of Science and Technology (HIST), Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
- Fujian Province Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, China
| | - Ashot Papikian
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, California, United States of America
| | - William A. Pastor
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, California, United States of America
| | - Guillaume Moissiard
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, California, United States of America
| | - Ajay A. Vashisht
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America
| | - Jeffery L. Dangl
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Howard Hughes Medical Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - James A. Wohlschlegel
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, United States of America
| | - Steven E. Jacobsen
- Department of Molecular, Cell and Developmental Biology, University of California at Los Angeles, Los Angeles, California, United States of America
- Howard Hughes Medical Institute, University of California at Los Angeles, Los Angeles, California, United States of America
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11
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Harris CJ, Baulcombe DC. Chlorophyll Content Assay to Quantify the Level of Necrosis Induced by Different R Gene/Elicitor Combinations after Transient Expression. Bio Protoc 2015; 5:e1670. [PMID: 28748201 DOI: 10.21769/bioprotoc.1670] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
This assay can be used to rapidly and accurately quantify levels of leaf necrosis induced after transient expression of R genes and elicitor combinations (Harris et al., 2013). It is based on the inverse correlation between level of necrosis and chlorophyll content in leaf tissue. It is adapted from the calculations described by (Strain et al., 1971).
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Affiliation(s)
- C Jake Harris
- Plant Sciences Department, Cambridge University, Cambridge, UK
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12
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Harris CJ, Molnar A, Müller SY, Baulcombe DC. FDF-PAGE: a powerful technique revealing previously undetected small RNAs sequestered by complementary transcripts. Nucleic Acids Res 2015; 43:7590-9. [PMID: 26071954 PMCID: PMC4551911 DOI: 10.1093/nar/gkv604] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 05/22/2015] [Accepted: 05/27/2015] [Indexed: 12/16/2022] Open
Abstract
Small RNAs, between 18nt and 30nt in length, are a diverse class of non-coding RNAs that mediate a range of cellular processes, from gene regulation to pathogen defense. They guide ribonucleoprotein complexes to their target nucleic acids by Watson-Crick base pairing. We report here that current techniques for small RNA detection and library generation are biased by formation of RNA duplexes. To address this problem, we established FDF-PAGE (fully-denaturing formaldehyde polyacrylamide gel electrophoresis) to prevent annealing of sRNAs to their complement. By applying FDF-PAGE, we provide evidence that both strands of viral small RNA are present in near equimolar ratios, indicating that the predominant precursor is a long double-stranded RNA. Comparing non-denaturing conditions to FDF-PAGE uncovered extensive sequestration of miRNAs in model organisms and allowed us to identify candidate small RNAs under the control of competing endogenous RNAs (ceRNAs). By revealing the full repertoire of small RNAs, we can begin to create a better understanding of small RNA mediated interactions.
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Affiliation(s)
- C Jake Harris
- Plant Sciences Department, Cambridge University, Cambridge, CB2 3EA, UK
| | - Attila Molnar
- Plant Sciences Department, Cambridge University, Cambridge, CB2 3EA, UK School of Biological Sciences, Edinburgh University, Edinburgh, EH9 3JH, UK
| | | | - David C Baulcombe
- Plant Sciences Department, Cambridge University, Cambridge, CB2 3EA, UK
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13
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Abstract
Genes encoding plant nucleotide-binding leucine-rich repeat (NB-LRR) proteins confer dominant resistance to diverse pathogens. The wild-type potato NB-LRR protein Rx confers resistance against a single strain of potato virus X (PVX), whereas LRR mutants protect against both a second PVX strain and the distantly related poplar mosaic virus (PopMV). In one of the Rx mutants there was a cost to the broad-spectrum resistance because the response to PopMV was transformed from a mild disease on plants carrying wild-type Rx to a trailing necrosis that killed the plant. To explore the use of secondary mutagenesis to eliminate this cost of broad-spectrum resistance, we performed random mutagenesis of the N-terminal domains of this broad-recognition version of Rx and isolated four mutants with a stronger response against the PopMV coat protein due to enhanced activation sensitivity. These mutations are located close to the nucleotide-binding pocket, a highly conserved structure that likely controls the "switch" between active and inactive NB-LRR conformations. Stable transgenic plants expressing one of these versions of Rx are resistant to the strains of PVX and the PopMV that previously caused trailing necrosis. We conclude from this work that artificial evolution of NB-LRR disease resistance genes in crops can be enhanced by modification of both activation and recognition phases, to both accentuate the positive and eliminate the negative aspects of disease resistance.
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Affiliation(s)
- C. Jake Harris
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom; and
| | - Erik J. Slootweg
- Laboratory of Nematology, Department of Plant Sciences, Wageningen University, 6708 PB, Wageningen, The Netherlands
| | - Aska Goverse
- Laboratory of Nematology, Department of Plant Sciences, Wageningen University, 6708 PB, Wageningen, The Netherlands
| | - David C. Baulcombe
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom; and
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14
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Abstract
A very efficient learning algorithm for model subset selection is introduced based on a new composite cost function that simultaneously optimizes the model approximation ability and model robustness and adequacy. The derived model parameters are estimated via forward orthogonal least squares, but the model subset selection cost function includes a D-optimality design criterion that maximizes the determinant of the design matrix of the subset to ensure the model robustness, adequacy, and parsimony of the final model. The proposed approach is based on the forward orthogonal least square (OLS) algorithm, such that new D-optimality-based cost function is constructed based on the orthogonalization process to gain computational advantages and hence to maintain the inherent advantage of computational efficiency associated with the conventional forward OLS approach. Illustrative examples are included to demonstrate the effectiveness of the new approach.
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Affiliation(s)
- X Hong
- Dept. of Cybern., Reading Univ., UK
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15
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Balasubramanian M, Smith K, Basel-Vanagaite L, Feingold MF, Brock P, Gowans GC, Vasudevan PC, Cresswell L, Taylor EJ, Harris CJ, Friedman N, Moran R, Feret H, Zackai EH, Theisen A, Rosenfeld JA, Parker MJ. Case series: 2q33.1 microdeletion syndrome--further delineation of the phenotype. J Med Genet 2011; 48:290-8. [PMID: 21343628 DOI: 10.1136/jmg.2010.084491] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Recurrent deletions of 2q32q33 have recently been reported as a new microdeletion syndrome, clinical features of which include significant learning difficulties, growth retardation, dysmorphic features, thin and sparse hair, feeding difficulties, and cleft or high palate. Haploinsufficiency of one gene within the deleted region, SATB2, has been suggested to be responsible for most of the features of the syndrome. This article describes seven previously unreported patients with deletions at 2q33.1, all partially overlapping the previously described critical region for the 2q33.1 microdeletion syndrome. The deletions ranged in size from 35 kb to 10.4 Mb, with the smallest deletion entirely within the SATB2 gene. Patients demonstrated significant developmental delay and challenging behaviour, a particular behavioural phenotype that seems to be emerging with more reported patients with this condition. One patient in this cohort has a deletion entirely within SATB2 and has a cleft palate, whereas several patients with larger deletions have a high arched palate. In addition, one other patient has significant orthopaedic problems with ligamentous laxity. Interestingly, this patient has a deletion that lies just distal to SATB2. The orthopaedic problems have not been reported previously and are possibly an additional feature of this syndrome. Overall, this report provides further evidence that the SATB2 gene is the critical gene in this microdeletion syndrome. In addition, because the individuals in this study range in age from 3-19 years, these patients will help define the natural progression of the phenotype in patients with this microdeletion.
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Affiliation(s)
- M Balasubramanian
- Sheffield Clinical Genetics Service, Sheffield NHS Foundation Trust, Western Bank, Sheffield S10 2TH, UK.
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16
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Atchison CJ, Lopman BA, Harris CJ, Tam CC, Iturriza Gómara M, Gray JJ. Clinical laboratory practices for the detection of rotavirus in England and Wales: can surveillance based on routine laboratory testing data be used to evaluate the impact of vaccination? Euro Surveill 2009; 14. [DOI: 10.2807/ese.14.20.19217-en] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two rotavirus vaccines have recently been licensed in Europe. Rotavirus surveillance data in many European countries are based on reports of laboratory-confirmed rotavirus infections. If surveillance data based on routine laboratory testing data are to be used to evaluate the impact of vaccination programmes, it is important to determine how the data are influenced by differences in testing practices, and how these practices are likely to affect the ability of the surveillance data to represent trends in rotavirus disease in the community. We conducted a survey of laboratory testing polices for rotavirus gastroenteritis in England and Wales in 2008. 60% (94/156) of laboratories responded to the survey. 91% of reporting laboratories offered routine testing for rotavirus all year round and 89% of laboratories offered routine rotavirus testing of all stool specimens from children under the age of five years. In 96% of laboratories, rotavirus detection was presently done either by rapid immunochromatographic tests or by enzyme-linked immunosorbent assay. Currently, rotavirus testing policies among laboratories in England and Wales are relatively homogenous. Therefore, surveillance based on laboratory testing data is likely to be representative of rotavirus disease trends in the community in the most frequently affected age groups (children under the age of five years) and could be used to help determine the impact of a rotavirus vaccine.
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Affiliation(s)
- C J Atchison
- Infectious Diseases Epidemiology Unit, Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - B A Lopman
- Gastrointestinal, Emerging and Zoonotic Infections Department, Centre for Infections, Health Protection Agency, London, United Kingdom
- Infectious Diseases Epidemiology Unit, Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - C J Harris
- Standards Unit, Department of Evaluations and Standards, Centre for Infections, Health Protection Agency, London, United Kingdom
| | - C C Tam
- Infectious Diseases Epidemiology Unit, Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - M Iturriza Gómara
- Enteric Virus Unit, Virus Reference Department, Centre for Infections, Health Protection Agency, London, United Kingdom
| | - J J Gray
- Enteric Virus Unit, Virus Reference Department, Centre for Infections, Health Protection Agency, London, United Kingdom
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17
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Chen S, Wolfgang A, Harris CJ, Hanzo L. Adaptive nonlinear least bit error-rate detection for symmetrical RBF beamforming. Neural Netw 2008; 21:358-67. [PMID: 18207699 DOI: 10.1016/j.neunet.2007.12.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 10/25/2007] [Accepted: 12/11/2007] [Indexed: 10/22/2022]
Abstract
A powerful symmetrical radial basis function (RBF) aided detector is proposed for nonlinear detection in so-called rank-deficient multiple-antenna assisted beamforming systems. By exploiting the inherent symmetry of the optimal Bayesian detection solution, the proposed RBF detector becomes capable of approaching the optimal Bayesian detection performance using channel-impaired training data. A novel nonlinear least bit error algorithm is derived for adaptive training of the symmetrical RBF detector based on a stochastic approximation to the Parzen window estimation of the detector output's probability density function. The proposed adaptive solution is capable of providing a signal-to-noise ratio gain in excess of 8 dB against the theoretical linear minimum bit error rate benchmark, when supporting four users with the aid of two receive antennas or seven users employing four receive antenna elements.
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Affiliation(s)
- S Chen
- School of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, UK.
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18
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Gan Q, Harris CJ. Linearization and state estimation of unknown discrete-time nonlinear dynamic systems using recurrent neurofuzzy networks. ACTA ACUST UNITED AC 2008; 29:802-17. [PMID: 18252359 DOI: 10.1109/3477.809034] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Model-based methods for the state estimation and control of linear systems have been well developed and widely applied. In practice, the underlying systems are often unknown and nonlinear. Therefore, data based model identification and associated linearization techniques are very important. Local linearization and feedback linearization have drawn considerable attention in recent years. In this paper, linearization techniques using neural networks are reviewed, together with theoretical difficulties associated with the application of feedback linearization. A recurrent neurofuzzy network with an analysis of variance (ANOVA) decomposition structure and its learning algorithm are proposed for linearizing unknown discrete-time nonlinear dynamic systems. It can be viewed as a method for approximate feedback linearization, as such it enlarges the class of nonlinear systems that can be feedback linearized using neural networks. Applications of this new method to state estimation are investigated with realistic simulation examples, which shows that the new method has useful practical properties such as model parametric parsimony and learning convergence, and is effective in dealing with complex unknown nonlinear systems.
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Affiliation(s)
- Q Gan
- Dept. of Electron. & Comput. Sci., Southampton Univ
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19
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Abstract
In this paper we address the stability of a class of non-linear fuzzy systems that can be decomposed into a set of local models characterized as Takagi-Sugeno models. This new approach includes a consideration of the input membership functions. Via this approach, a reduction in the number of candidate Lyapunov functions and associated linear matrix inequalities (LMIs) is produced. This approach significantly reduces the computational load associated with determining closed loop stability as the input dimension increases.
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Affiliation(s)
- M Feng
- Dept. of Electron. & Comput. Sci., Southampton Univ
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20
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Chen S, Wang XX, Hong X, Harris CJ. Kernel Classifier Construction Using Orthogonal Forward Selection and Boosting With Fisher Ratio Class Separability Measure. ACTA ACUST UNITED AC 2006; 17:1652-6. [PMID: 17131680 DOI: 10.1109/tnn.2006.881487] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A greedy technique is proposed to construct parsimonious kernel classifiers using the orthogonal forward selection method and boosting based on Fisher ratio for class separability measure. Unlike most kernel classification methods, which restrict kernel means to the training input data and use a fixed common variance for all the kernel terms, the proposed technique can tune both the mean vector and diagonal covariance matrix of individual kernel by incrementally maximizing Fisher ratio for class separability measure. An efficient weighted optimization method is developed based on boosting to append kernels one by one in an orthogonal forward selection procedure. Experimental results obtained using this construction technique demonstrate that it offers a viable alternative to the existing state-of-the-art kernel modeling methods for constructing sparse Gaussian radial basis function network classifiers that generalize well.
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21
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Metz LM, Patten SB, Archibald CJ, Bakker JI, Harris CJ, Patry DG, Bell RB, Yeung M, Murphy WF, Stoian CA, Billesberger K, Tillotson L, Peters S, McGowan D. The effect of immunomodulatory treatment on multiple sclerosis fatigue. J Neurol Neurosurg Psychiatry 2004; 75:1045-7. [PMID: 15201369 PMCID: PMC1739126 DOI: 10.1136/jnnp.2002.007724] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE To assess the effects of glatiramer acetate and beta interferon on fatigue in multiple sclerosis. METHODS Fatigue was measured at baseline and six months using the fatigue impact scale (FIS). Groups (glatiramer acetate and beta interferon) were evaluated for the proportion improved, using Fisher's exact test. Logistic regression analysis assessed the relation between treatment group and improvement and controlled for confounding variables. RESULTS Six month paired FIS assessments were available for 218 patients (76% female). Ages ranged between 19 and 61 years, with 86% having relapsing-remitting disease. Glatiramer acetate was used by 61% and beta interferon by 39%. At baseline, total FIS and subscale scores were comparable in the two groups. More patients improved on glatiramer acetate than on beta interferon on total FIS (24.8% v 12.9%, p = 0.033; adjusted odds ratio = 2.36, 95% confidence interval 1.03 to 5.42), and on physical (28.6% v 14.1%, p = 0.013) and cognitive subscales (21.1% v 10.6%, p = 0.045). Logistic regression analysis confirmed the association between glatiramer acetate use and improved fatigue, after accounting for baseline group differences. CONCLUSIONS The odds of reduced multiple sclerosis fatigue were around twice as great with glatiramer acetate treatment as with beta interferon. Confirmation of this result is required.
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Affiliation(s)
- L M Metz
- Department of Clinical Neurosciences, University of Calgary, Alberta, Canada.
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22
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Chen S, Gunn SR, Harris CJ. Errata to "The relevance vector machine technique for channel equalization application". IEEE Trans Neural Netw 2002; 13:1024. [PMID: 18244497 DOI: 10.1109/tnn.2002.1021902] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
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Abstract
There has been an increasing interest in kernel-based techniques, such as support vector techniques, regularization networks, and gaussian processes. There are inner relationships among those techniques, with the kernel function playing a central role. This article discusses a new class of kernel functions derived from the so-called frames in a function Hilbert space.
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Affiliation(s)
- J B Gao
- Image, Speech and Intelligent System Research Group, Department of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, UK
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24
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Abstract
Recent in-vitro and animal data show that cyclooxygenase-2 has an integral role in the physiology and pathophysiology of the kidney. Cyclooxygenase-2 regulates renin-angiotensin secretion, and thereby glomerular filtration rate and sodium homeostasis. It is also important for protecting against hypertonic stress. As a consequence, it is not surprising that clinical data verify that selective inhibitors of cyclooxygenase-2 affect renal function to a degree similar to that which has previously been documented with nonselective nonsteroidal anti-inflammatory drugs.
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Affiliation(s)
- C J Harris
- Division of Clinical Pharmacology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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Thorne AP, Harris CJ, Wynne-Jones I, Learner RCM, Cox G. A Fourier transform spectrometer for the vacuum ultraviolet: design and performance. ACTA ACUST UNITED AC 2000. [DOI: 10.1088/0022-3735/20/1/010] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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26
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Harris CJ. Self audits ensure MDS (minimum data set) accuracy. Provider 2000; 26:28-9, 33. [PMID: 11183719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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27
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Wisskirchen FM, Doyle PM, Gough SL, Harris CJ, Marshall I. Bioactive beta-bend structures for the antagonist halpha CGRP(8 - 37) at the CGRP(1) receptor of the rat pulmonary artery. Br J Pharmacol 2000; 129:1049-55. [PMID: 10696108 PMCID: PMC1571929 DOI: 10.1038/sj.bjp.0703152] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/1999] [Revised: 12/08/1999] [Accepted: 12/10/1999] [Indexed: 01/15/2023] Open
Abstract
The aim of this study was to determine beta-bend structures and the role of the N- and C-terminus in the antagonist halpha CGRP(8 - 37) at the rat pulmonary artery CGRP receptor mediating halpha CGRP relaxation. Halpha CGRP(8 - 37) Pro(16) (10(-6) M), with a bend-biasing residue (proline) at position 16, did not antagonize halpha CGRP responses, while a structure-conserving amino acid (alanine(16)) at the same position retained antagonist activity (apparent pK(B) 6.6+/-0.1; 10(-6) M). Halpha CGRP(8 - 37) Pro(19) (10(-6) M), with proline at position 19 was an antagonist (apparent pK(B) 6.9+/-0.1). Incorporation of a beta-bend forcing residue, BTD (beta-turn dipeptide), at positions 19 and 20 in halpha CGRP(8 - 37) (10(-6) M) antagonized halpha CGRP responses (apparent pK(B) 7.2+/-0.2); and BTD at positions 19,20 and 33,34 within halpha CGRP(8 - 37) was a competitive antagonist (pA(2) 7.2; Schild plot slope 1.0+/-0.1). Halpha CGRP(8 - 37) analogues, substituted at the N-terminus by either glycine(8) or des-NH(2) valine(8) or proline(8) were all antagonists (apparent pK(B) 6.9+/-0.1; (10(-6) M), 7.0+/-0.1 (10(-6) M), and pA(2) 7.0 (slope 1.0+/-0.2), respectively); while replacements by proline(8) together with glutamic acid(10,14) in halpha CGRP(8 - 37) (10(-6) M) or alanine amide(37) at the C-terminus of halpha CGRP(8 - 37) (10(-5) M) were both inactive compounds. In conclusion, possible bioactive structures of halpha CGRP(8 - 37) include two beta-bends (at 18 - 21 and 32 - 35), which were mimicked by BTD incorporation. Within halpha CGRP(8 - 37), the N-terminus is not essential for antagonism while the C-terminus may interact directly with CGRP(1) receptors in the rat pulmonary artery.
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Affiliation(s)
- F M Wisskirchen
- Department of Pharmacology, University College London, Gower Street, London WC1E 6BT
| | - P M Doyle
- Department of Medicinal Chemistry, GlaxoWellcome, Beckenham, Kent BR3 3BS
| | - S L Gough
- Department of Medicinal Chemistry, GlaxoWellcome, Beckenham, Kent BR3 3BS
| | - C J Harris
- Department of Medicinal Chemistry, GlaxoWellcome, Beckenham, Kent BR3 3BS
| | - I Marshall
- Department of Pharmacology, University College London, Gower Street, London WC1E 6BT
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28
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Wisskirchen FM, Doyle PM, Gough SL, Harris CJ, Marshall I. Conformational restraints revealing bioactive beta-bend structures for halpha CGRP8-37 at the CGRP2 receptor of the rat prostatic vas deferens. Br J Pharmacol 1999; 126:1163-70. [PMID: 10205004 PMCID: PMC1565896 DOI: 10.1038/sj.bjp.0702432] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/1998] [Revised: 12/15/1998] [Accepted: 12/21/1998] [Indexed: 11/09/2022] Open
Abstract
1. The main aim of this study was to identify putative beta-bends and the role of the N- and C-terminus in the CGRP receptor antagonist halpha CGRP8-37, which was measured against halpha CGRP inhibition of twitch responses in the rat prostatic vas deferens. 2. With a bend-biasing residue (proline) at position 16 in halpha CGRP8-37 (10(-5) M) an inactive compound was produced, while alanine at the same position retained antagonist activity (apparent pKB 5.6+/-0.1 at 10(-5) M). Proline at position 19 within halpha CGRP8-37 (10(-5) M) was an antagonist (apparent pKB 5.8+/-0.1). 3. Incorporation of a bend-forcing structure (beta-turn dipeptide or BTD) at either positions 19,20 or 33,34 in halpha CGRP8-37 (10(-5) M) antagonized halpha CGRP responses (apparent pKB 6.0+/-0.1 and 6.1+/-0.1, respectively). Replacement by BTD at both positions 19,20 and 33,34 within halpha CGRP8-37 competitively antagonized responses to halpha CGRP (pA2 6.2; Schild plot slope 1.0+/-0.1). 4. Halpha CGRP8-37 analogues (10(-5) M), substituted at the N-terminus by either glycine8, or des-NH2 valine8 or proline8 were all antagonists against halpha CGRP (apparent pKB 6.1+/-0.1, 6.5+/-0.1 and 6.1+/-0.1, respectively), while halpha CGRP8-37 (10(-5) M) substituted in three places by proline8 and glutamic acid10,14 was inactive. 5. Replacement of the C-terminus by alanine amide37 in halpha CGRP8-37 (10(-5) M) failed to antagonize halpha CGRP responses. 6. Peptidase inhibitors did not alter either the agonist potency of halpha CGRP or the antagonist affinities of halpha CGRP8-37 BTD19,20 and 33,34 and halpha CGRP8-37 Gly8 (against halpha CGRP responses). 7. In conclusion, two beta-bends at positions 18-21 and 32-35 are compatible with high affinity by BTD and is the first approach of modelling the bioactive structure of halpha CGRP8-37. Further, the N-terminus of halpha CGRP8-37 is not essential for antagonism, while the C-terminus interacts directly with CGRP receptor binding sites of the rat vas deferens.
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Affiliation(s)
- F M Wisskirchen
- Department of Pharmacology, University College London, Gower Street, London WC1E 6BT, England
| | - P M Doyle
- Department of Medicinal Chemistry, Glaxo Wellcome, Beckenham, Kent BR3 3BS, England
| | - S L Gough
- Department of Medicinal Chemistry, Glaxo Wellcome, Beckenham, Kent BR3 3BS, England
| | - C J Harris
- Department of Medicinal Chemistry, Glaxo Wellcome, Beckenham, Kent BR3 3BS, England
| | - I Marshall
- Department of Pharmacology, University College London, Gower Street, London WC1E 6BT, England
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Harris CJ. RUGs: a new bridge to payment. Provider 1998; 24:suppl 2, 11. [PMID: 10180700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Affiliation(s)
- C J Harris
- Elder Solutions Health Care Consultants, Vergennes, VT, USA
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Viles JH, Patel SU, Mitchell JB, Moody CM, Justice DE, Uppenbrink J, Doyle PM, Harris CJ, Sadler PJ, Thornton JM. Design, synthesis and structure of a zinc finger with an artificial beta-turn. J Mol Biol 1998; 279:973-86. [PMID: 9642075 DOI: 10.1006/jmbi.1998.1764] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have incorporated a bicyclic beta-turn mimetic (BTD; beta-turn dipeptide) into a zinc finger, creating a zinc finger with an artificial beta-turn. The designed peptide chelates zinc and has the same fold as the unmodified native zinc finger (finger 3 of the human YY1 protein). A combination of 1H NMR and structure calculations reveals that, in solution, this zinc finger has a fold similar to the known wild-type crystal structure and to other zinc fingers containing the consensus sequence X3-Cys-X4-Cys-X12-His-X3-His-X. The peptide was designed with BTD between the chelating cysteine residues, with BTD forming a type II' beta-turn linking the two strands of a distorted anti-parallel beta-sheet. The C-terminal portion of the peptide forms a helix with zinc co-ordinating histidine residues on successive turns of the helix. This work represents a step towards developing methods by which parts of a target protein may be replaced by peptide mimetics.
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Affiliation(s)
- J H Viles
- Department of Chemistry, Birkbeck College, University of London, Gordon House, London, WC1H 0PP, UK
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Harris CJ. Detecting depression. Provider 1998; 24:67-8. [PMID: 10180047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Affiliation(s)
- C J Harris
- Elder Solutions Health Care Consultants, Vergennes, VT, USA
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Dewald G, Stallard R, Al Saadi A, Arnold S, Bader PI, Blough R, Chen K, Elejalde BR, Harris CJ, Higgins RR, Hoeltge GA, Hsu WT, Kubic V, McCorquodale DJ, Micale MA, Moore JW, Phillips RM, Scheib-Wixted S, Schwartz S, Siembieda S, Strole K, VanTuinen P, Vance GH, Wiktor A, Zinsmeister A. A multicenter investigation with interphase fluorescence in situ hybridization using X- and Y-chromosome probes. Am J Med Genet 1998; 76:318-326. [PMID: 9545096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Twenty-six laboratories used X and Y chromosome probes and the same procedures to process and examine 15,600 metaphases and 49,400 interphases from Phaseolus vulgaris-leucoagglutinin (PHA)-stimulated lymphocytes. In Part I, each laboratory scored 50 metaphases and 200 interphases from a normal male and a normal female from its own practice. In Part II, each laboratory scored 50 metaphases and 200 interphases on slides prepared by a central laboratory from a normal male and a normal female and three mixtures of cells from the male and female. In Part III, each laboratory scored 50 metaphases (in samples of 5, 10, 15, and 20) and 100 interphases (in samples of 5, 10, 15, 20, and 50) on new, coded slides of the same specimens used in Part II. Metaphases from male specimens were scored as 98-99% XY with no XX cells, and 97-98% of interphases were scored as XY with 0.04% XX cells. Metaphases from female specimens were scored as 96-97% XX with 0.03% XY cells, and 94-96% of interphases were scored as XX with 0.05% XY cells. Considering the data as a model for any probe used with fluorescence in situ hybridization (FISH), a statistical approach assessing the impact of analytical sensitivity on the numbers of observations required to assay for potential mosaicisms and chimerisms is discussed. The workload associated with processing slides and scoring 50 metaphases and 200 interphases using FISH averaged 27.1 and 28.6 minutes, respectively. This study indicates that multiple laboratories can test/develop guidelines for the rapid, efficacious, and cost-effective integration of FISH into clinical service.
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Affiliation(s)
- G Dewald
- Mayo Clinic, Rochester, Minnesota 55905, USA
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An PE, Brown B, Harris CJ. On the convergence rate performance of the normalized least-mean-square adaptation. IEEE Trans Neural Netw 1997; 8:1211-4. [PMID: 18255724 DOI: 10.1109/72.623223] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This paper compares the convergence rate performance of the normalized least-mean-square (NLMS) algorithm to that of the standard least-mean-square (LMS) algorithm, which is based on a well-known interpretation of the NLMS algorithm as a form of the LMS via input normalization. With this interpretation, the analysis is considerably simplified and the difference in rate of parameter convergence can be compared directly by evaluating both the condition number of the normalized and unnormalized input correlation matrix. This paper derives the condition number expressions for the normalized input correlation matrix of which the arbitrary-length filter model is linear with respect to its adaptable parameters and contain only two distinct unnormalized eigenvalues. These expressions, which require that the input samples be statistically stationary and zero-mean Gaussian distributed, provide an important insight into the relative convergence performance of the NLMS algorithm to that of the LMS as a function of filter length. This paper also provides a conjecture which set bounds on the NLMS condition number for any arbitrary number of distinct unnormalized eigenvalues.
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Affiliation(s)
- P E An
- Dept. of Ocean Eng., Florida Atlantic Univ., Boca Raton, FL
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Barry MJ, Fowler FJ, Bin L, Pitts JC, Harris CJ, Mulley AG. The natural history of patients with benign prostatic hyperplasia as diagnosed by North American urologists. J Urol 1997; 157:10-4; discussion 14-5. [PMID: 8976204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE We defined outcomes for men with a clinical diagnosis of benign prostatic hyperplasia. MATERIALS AND METHODS We followed for 4 years 500 candidates for elective prostatectomy treated nonoperatively in 5 North American urology practices. RESULTS There were 371 survivors with complete data at 4 years. Of 60 men with mild, 245 with moderate and 66 with severe baseline symptoms 10, 24 and 39%, respectively, had undergone surgery; 27, 31 and 27%, respectively, were on pharmacological therapy, and 63, 45 and 33%, respectively, were off active treatment at 4 years. Mild or moderate symptoms were noted at 4 years in 83, 59 and 23% of the patients, respectively, while 17, 41 and 77%, respectively, had severe symptoms or had undergone surgery. CONCLUSIONS Outcomes for men with a clinical diagnosis of benign prostatic hyperplasia depend on initial symptom severity. However, the course of symptoms also varies among patients even with the same initial symptom severity.
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Affiliation(s)
- M J Barry
- Medical Practices Evaluation Center, Massachusetts General Hospital, Boston, USA
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Viles JH, Mitchell JB, Gough SL, Doyle PM, Harris CJ, Sadler PJ, Thornton JM. Multiple solution conformations of the integrin-binding cyclic pentapeptide cyclo(-Ser-D-Leu-Asp-Val-Pro-). Analysis of the (phi, psi) space available to cyclic pentapeptides. Eur J Biochem 1996; 242:352-62. [PMID: 8973654 DOI: 10.1111/j.1432-1033.1996.0352r.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The aqueous solution structure of the cyclic pentapeptide cyclo(-Ser-D-Leu-Asp-Val-Pro-) has been determined by two-dimensional 1H-NMR spectroscopy, combined with a conformational search and distance-geometry calculations. As many as five conformers in slow exchange were observed, and the rate of interconversion between components was measured from the build-up rates of exchange peaks. NMR data allowed the structures of the two predominant conformers to be determined. The major component (66%) contained a cis-proline as part of a type-VIa2 beta-turn encompassing residues Asp-Val-cis-Pro-Ser. The second component (16%) contained only trans-amide bonds, and a type-VIII beta-turn formed by residues Val-Pro-Ser-D-Leu. These structures are discussed in relation to the (phi, psi), space available to the cyclic pentapeptide, determined by a conformational search, and in relation to previously published cyclic-pentapeptide structures. The molecule exhibits activity in a scintillation-proximity assay for the inhibition of the interaction between the integrin very-late antigen-4 (VLA-4; alpha 4 beta 1) and vascular-cell-adhesion molecule-1 (VCAM-1). The structure/activity relationship of the LDV sequence is discussed and related to the recently published X-ray structure of VCAM-1. The relevance of the work to the design of anti-inflammatory drugs is discussed.
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Affiliation(s)
- J H Viles
- Department of Chemistry, Birkbeck College, University of London, UK
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Abstract
OBJECTIVE To report the occurrence, clinical characteristics and genealogical analysis of multiple sclerosis in the Hutterites of North-Western United States and Western Canada. BACKGROUND The incidence of multiple sclerosis is reported to be lower or rare in certain ethnic groups and genetic isolates and was previously observed to be absent in the Hutterite population. METHODS After long-term surveillance, six patients were identified and clinical examinations and laboratory investigations including VER and MRI were completed. RESULTS The six cases included two brothers, two first cousins, male and female, another male and female, all representing two of the three endogamous groups of Hutterites, are linked to two common ancestors through lines of descent dating to 1723. The individual pedigrees were analyzed from extensive genealogical records covering eight generations. CONCLUSION The incidence of multiple sclerosis in Hutterites is low in a high risk area of North America. A specific mode of inheritance pattern has not been established and a common founder effect may play a role in the development of multiple sclerosis. The genetic contribution of the Hutterites seems greater than previously recognized.
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Affiliation(s)
- W J Hader
- Department of Rehabilitation Medicine, College of Medicine, University of Saskatchewan, Saskatoon, Canada
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Dewald GW, Stallard R, Bader PI, Chen K, Zenger-Hain J, Harris CJ, Higgins R, Hirsch B, Hsu WT, Johnson E, Kubic V, Kurczynski TW, Malone JM, McCorquodale DJ, Meilinger K, Meisner LF, Moore JW, Schwartz S, Siembieda S, Storto PD, Vance G, Van Tuinen P, Wiktor A, Yung JF. Toward quality assurance for metaphase FISH: a multicenter experience. Am J Med Genet 1996; 65:190-6. [PMID: 9240742 DOI: 10.1002/(sici)1096-8628(19961028)65:3<190::aid-ajmg4>3.0.co;2-u] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Although fluorescent in situ hybridization (FISH) is rapidly becoming a part of clinical cytogenetics, no organization sponsors multicenter determinations of the efficacy of probes. We report on 23 laboratories that volunteered to provide slides and to use a probe for small nuclear ribonucleoprotein polypeptide N (SNRPN) and a control locus. Experiences with FISH for these laboratories during 1994 ranged from 0 to 645 utilizations (median = 84) involving blood, amniotic fluid, and bone marrow. In an initial study of hybridization efficiency, the median percentage of metaphases from normal individuals showing two SNRPN and two control signals for slides prepared at each site was 97.0 (range = 74-100); for slides prepared by a central laboratory, it was 97.8 (range = 81.6-100). In a subsequent blind study, each laboratory attempted to score 5 metaphases from each of 23 specimens [8 with del(15)(q11.2-->q12) and 15 with normal #15 chromosomes]. Of 529 challenges, the correct SNRPN pattern was found in 5 of 5 metaphases in 457 (86%) and in 4 of 5 in 33 (6%). Ambiguous, incomplete, or no results were reported for 32 (6%) challenges. Seven (1%) diagnostic errors were made, including 6 false positives and 1 false negative: 1 laboratory made 3 errors, 1 made 2, and 2 made 1 each. Most errors and inconsistencies seemed due to inexperience with FISH. The working time to process and analyze slides singly averaged 49.5 min; slides processed in batches of 4 and analyzed singly required 36.9 min. We conclude that proficiency testing for FISH by using an extensive array of challenges is possible and that multiple centers can collaborate to test probes and to evaluate costs.
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Affiliation(s)
- G W Dewald
- Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA
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Dewald G, Stallard R, Bader PI, Chen K, Zenger-Hain J, Harris CJ, Higgins R, Hirsch B, Hsu WT, Johnson E, Kubic V, Kurczynski TW, Malone JM, McCorquodale DJ, Meilinger K, Meisner LF, Moore JW, Schwartz S, Siembieda S, Storto PD, Vance G, Van Tuinen P, Wiktor A, Yung JF. Toward quality assurance for metaphase FISH: a multi-center experience. Am J Med Genet 1996; 64:539-45. [PMID: 8870919 DOI: 10.1002/(sici)1096-8628(19960906)64:4<539::aid-ajmg3>3.0.co;2-k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Although fluorescent in situ hybridization (FISH) is rapidly becoming a part of clinical cytogenetics, no organization sponsors multi-center determinations of the efficacy of probes. We report on 23 laboratories that volunteered to provide slides and to use a probe for SNRPN and a control locus. Experiences with FISH for these laboratories during 1994 ranged from 0 to 645 utilizations (median = 84) involving blood, amniotic fluid and bone marrow. In an initial study of hybridization efficiency, the median percentage of metaphases from normal individuals showing two SNRPN and 2 control signals for slides prepared at each site was 97.0 (range = 74-100); for slides prepared by a central laboratory, it was 97.8 (range = 81.6-100). In a subsequent blind study, each laboratory attempted to score 5 metaphases from each of 23 specimens [8 with del(15) (q11.2-->q12) and 15 with normal 15 chromosomes]. Of 529 challenges, the correct SNRPN pattern was found in 5 of 5 metaphases in 457 (86%) and in 4 of 5 in 33 (6%). Ambiguous, incomplete or no results were reported for 32 (6%) challenges. Seven (1%) diagnostic errors were made including 6 false positives and 1 false negative: 1 laboratory made 3 errors, 1 made 2, and 2 made 1 each. Most errors and inconsistencies seemed due to inexperience with FISH. The working time to process and analyze slides singly averaged 49.5 minutes; slides processed in batches of 4 and analyzed singly required 36.9 minutes. We conclude that proficiency testing for FISH using an extensive array of challenges is possible and that multiple centers can collaborate to test probes and to evaluate costs.
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Affiliation(s)
- G Dewald
- Cytogenetics Laboratory, Mayo Clinic, Rochester, MN 55905, USA
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Jones DT, Moody CM, Uppenbrink J, Viles JH, Doyle PM, Harris CJ, Pearl LH, Sadler PJ, Thornton JM. Towards meeting the Paracelsus Challenge: The design, synthesis, and characterization of paracelsin-43, an alpha-helical protein with over 50% sequence identity to an all-beta protein. Proteins 1996; 24:502-13. [PMID: 8859998 DOI: 10.1002/(sici)1097-0134(199604)24:4<502::aid-prot9>3.0.co;2-f] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In response to the Paracelsus Challenge (Rose and Creamer, Proteins, 19:1-3, 1994), we present here the design, synthesis, and characterization of a helical protein, whose sequence is 50% identical to that of an all-beta protein. The new sequence was derived by applying an inverse protein folding approach, in which the sequence was optimized to "fit" the new helical structure, but constrained to retain 50% of the original amino acid residues. The program utilizes a genetic algorithm to optimize the sequence, together with empirical potentials of mean force to evaluate the sequence-structure compatibility. Although the designed sequence has little ordered (secondary) structure in water, circular dichroism and nuclear magnetic resonance data show clear evidence for significant helical content in water/ethylene glycol and in water/methanol mixtures at low temperatures, as well as melting behavior indicative of cooperative folding. We believe that this represents a significant step toward meeting the Paracelsus Challenge.
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Affiliation(s)
- D T Jones
- Department of Biochemistry and Molecular Biology, University College, London, UK
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Barraclough P, Bolofo ML, Giles H, Gillam J, Harris CJ, Kelly MG, Leff P, McNeill A, Robertson AD, Stepney RJ, Whittle BJ. Synthesis of Hexahydrocyclopentimidazol-2-(1H)-one derivatives displaying selective DP-receptor agonist properties. Bioorg Med Chem 1996; 4:81-90. [PMID: 8689243 DOI: 10.1016/0968-0896(95)00173-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The rationale for investigating conformationally restricted analogues of BW245C as DP-receptor ligands and the syntheses of three such racemic bicyclic imidazolidinone analogues are described. Compounds 7 (BW587C), 8 (BW480C85), and 9 (BW572C85) were found to be potent inhibitors of human platelet aggregation and selective DP-receptor agonists in washed platelet and jugular vein isolated tissue assays.
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Affiliation(s)
- P Barraclough
- Department of Medicinal Chemistry, Wellcome Research Laboratories, Beckenham, Kent, U.K
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Crowe G, Harris CJ, Forster GE, Goh BT. Integrating pharmacy into the primary care team. "One stop clinic" has advantages for patients. BMJ 1995; 311:753. [PMID: 7549718 PMCID: PMC2550751 DOI: 10.1136/bmj.311.7007.753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Abstract
BACKGROUND Severe spasticity unresponsive to oral drugs may respond satisfactorily to baclofen delivered intrathecally. METHODS Intrathecal baclofen (IB) therapy delivered by means of implanted infusion pumps was used for nine patients with severe spasticity. Six patients had multiple sclerosis, two cervical spinal cord injury, and one head injury. All were non-ambulatory. RESULTS Patients showed improvement in many areas, including ability to transfer, seating, pain control, personal care, and liability to skin breakdown. Before IB therapy, only three of the nine patients were able to live at home in the community and six were institutionalized. At the end of our follow-up period, only one patient remained institutionalized, three lived in group homes and five lived at home in the community. In the year preceding pump implantation, the nine patients spent a total of 755 days in acute care hospitals. In the year following onset of IB therapy, they spent only 259 days in hospital. CONCLUSIONS IB therapy can improve patient quality of life and can be cost-effective in carefully selected patients with severe spasticity and disability. The drug delivery catheter is that part of the therapeutic system most vulnerable to failure. Because of the varied expertise required to manage these patients effectively, and the potential for a variety of complications, it is essential that an IB program is supported by a well-organized multi-disciplinary medical team.
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Abstract
This paper outlines some of the theoretical and practical developments being made in neurofuzzy systems. As the name suggests, neurofuzzy networks were developed by fusing the ideas that originated in the fields of neural and fuzzy systems. A neurofuzzy network attempts to combine the transparent, linguistic, symbolic representation associated with fuzzy logic with the architecture and learning rules commonly used in neural networks. These hybrid structures have both a qualitative and a quantitative interpretation and can overcome some of the difficulties associated with solely neural algorithms which can usually be regarded as black box mappings, and with fuzzy systems where few modelling and learning theories existed. Both B-spline and Gaussian Radial Basis Function networks can be regarded as neurofuzzy systems and soft inductive learning algorithms can be used to extract unknown, qualitative information about the relationships contained in the training data. In a similar manner, qualitative rules or information about the network's structure can be used to initialise the system. These areas, coupled with the extensive work being carried out on theoretically analysing their modelling, convergence and stability properties means that this research topic is highly applicable in "intelligent" modelling and control problems. Apart from outlining this work, the paper also discusses a wide variety of open research questions and suggests areas where new efforts may be fruitfully applied.
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Affiliation(s)
- M Brown
- Department of Electronics and Computer Science, University of Southampton, Hants, UK
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Abstract
BACKGROUND Some patients with reflex sympathetic dystrophy (RD) develop intractable symptoms unresponsive to conventional therapy. Recently, intrathecal morphine therapy has been used with some success in such patients. METHODS The clinical course of two patients with intractable reflex sympathetic dystrophy (RSD) is described. Both patients developed intractable leg pain, swelling and autonomic changes after a leg injury. Numerous medical treatments and surgical sympathectomies failed to provide long term relief. RESULTS Relatively satisfactory symptom control was achieved only with the use of long term intrathecal morphine therapy delivered by subcutaneously implanted infusion pumps. Exacerbations of the RSD continued to occur, at times in association with further leg trauma, but these could be controlled by a temporary escalation of the intrathecal morphine dose. Complications of morphine therapy were relatively minor. A red rash appearing over the pump site was the first sign that a drug catheter break had occurred, necessitating surgical catheter revision. CONCLUSION Long term intrathecal morphine therapy is a useful treatment option for patients with intractable severe RSD who have failed other therapies and remain markedly disabled.
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Affiliation(s)
- W J Becker
- Department of Clinical Neurosciences, University of Calgary, Alberta, Canada
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46
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Brown M, Harris CJ. Comments on "Learning convergence in the cerebellar model articulation controller". IEEE Trans Neural Netw 1995; 6:1016-1018. [PMID: 18263392 DOI: 10.1109/72.392267] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The commenter refers to the paper by Wong-Sideris (ibid. vol.3, p.115-21 (1992)) claiming that the original Albus CMAC (or binary CMAC) is capable of learning an arbitrary multivariate lookup table, the linear optimization process is strictly positive definite, and that the basis functions are linearly independent, given sufficient training data. In recent work by Brown et al. (1994), however, it has been proved that the multivariate binary CMAC is unable to learn certain multivariate lookup tables and the number of such orthogonal functions increases exponentially as the generalization parameter is increased. A simple 2D orthogonal function is presented as a counterexample to the original theory. It is also demonstrated that the basis functions are-always linearly dependent, both for the univariate and the multivariate case, and hence the linear optimization process is only positive semi-definite and there always exists an infinite number of possible optimal weight vectors.
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Affiliation(s)
- M Brown
- Dept. of Aeronaut. and Astronaut., Southampton Univ
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47
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Abstract
Supervised parameter adaptation in many artificial neural networks is largely based on an instantaneous version of gradient descent called the least-mean-square (LMS) algorithm. This paper considers only neural models which are linear with respect to their adaptable parameters and has two major contributions. First, it derives an expression for the gradient-noise covariance under the assumption that the input samples are real, stationary, Gaussian distributed but can be partially correlated. This expression relates the gradient correlation and input correlation matrices to the gradient-noise covariance and explains why the gradient noise generally correlates maximally with the steepest principal axis and minimally with the one of the smallest curvature, regardless of the magnitude of the weight error. Second, a recursive expression for the weight-error correlation matrix is derived in a straightforward manner using the gradient-noise covariance, and comparisons are drawn with the complex LMS algorithm.
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Affiliation(s)
- P E An
- Dept. of Electron. and Comput. Sci., Southampton Univ
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48
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Harris CJ. Why not include contact tracing in HIV prevention? Ann Intern Med 1994; 121:388-9. [PMID: 8042842 DOI: 10.7326/0003-4819-121-5-199409010-00024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
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49
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Harris CJ. Nurse management 2000. Provider 1994; 20:42, 44. [PMID: 10135535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Affiliation(s)
- C J Harris
- Marlin Management Services, Burlington, VT
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Sanderson PN, Glen RC, Payne AW, Hudson BD, Heide C, Tranter GE, Doyle PM, Harris CJ. Characterisation of the solution conformation of a cyclic RGD peptide analogue by NMR spectroscopy allied with a genetic algorithm approach and constrained molecular dynamics. Int J Pept Protein Res 1994; 43:588-96. [PMID: 7928090 DOI: 10.1111/j.1399-3011.1994.tb00561.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The solution conformation of a cyclic RGD peptide analogue, cyclo-(S,S)-2-mercaptobenzoate-arginine-glycine-aspartate-2-mer captoanilide, has been determined via two independent approaches for the searching of conformational space and identification of conformations consistent with NMR and CD spectroscopic data: (i) the use of a binary genetic algorithm and (ii) a molecular dynamics simulation. Inter-proton distances were obtained via analysis of cross-peak volumes from a two-dimensional ROESY NMR spectroscopy experiment at 600 MHz and were used as constraints for the computational calculations. The mercaptoanilide amide proton resonance chemical shift had a very small temperature coefficient, indicating that this proton was hydrogen-bonded. Circular dichroism data showed that, in solution, the torsion angle about the disulfide bond was negative, consistent with one of the distinct conformations around this bond in the 200 ps molecular dynamics simulation. The backbone conformations of the structures resulting from the two different approaches were very similar.
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Affiliation(s)
- P N Sanderson
- Department of Physical Sciences, Wellcome Research Laboratories, Beckenham, Kent, UK
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