62 results on '"G JT"'
Search Results
2. Comparison of Isometric Force Control Measures in Spastic Muscle of Poststroke Individuals Before and After Graded Resistive Exercise
- Author
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Miller, G JT, primary, Light, K, additional, and Kellogg, R., additional
- Published
- 1995
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3. Comparison of Isometric Force Control Measures in Spastic Muscle of Poststroke Individuals Before and After Graded Resistive Exercise
- Author
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G Jt Miller, Kathye E. Light, and R. Kellogg
- Subjects
medicine.medical_specialty ,Physical medicine and rehabilitation ,Resistive exercise ,business.industry ,Rehabilitation ,medicine ,Physical therapy ,Spastic ,Physical Therapy, Sports Therapy and Rehabilitation ,Neurology (clinical) ,Isometric exercise ,business - Published
- 1995
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4. ATTENDING OUR OWN BUSINESS.
- Author
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W. G. JT
- Published
- 1874
5. Association of ABO blood groups with the severity of coronary artery disease in southern India population: A prospective cross-sectional study.
- Author
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Pai M U, Samanth J, Rao S, V R, A M, P G, Shah K, Kumar V, Jose J, Jabeen A, Lewis JH, G JT, Suresh A, and Haque N
- Subjects
- Humans, ABO Blood-Group System, Cross-Sectional Studies, Prospective Studies, India epidemiology, Coronary Angiography, Severity of Illness Index, Coronary Artery Disease diagnosis, Coronary Artery Disease epidemiology
- Abstract
This study aimed to find an association between ABO blood groups with presence and severity of Coronary artery disease (CAD) among Indian population. 1500 patients undergoing elective coronary angiogram (CAG) at a tertiary care hospital in Karnataka were enrolled in the study. Baseline demographic data and the presence of cardiac comorbidities were documented. Data from baseline echocardiography and angiographic studies were compiled. The incidence of CAD was higher among patients with blood group A. Blood group A also showed a higher incidence of acute coronary syndrome (ACS), left ventricular dysfunction, triple vessel disease, and severe CAD among the patients who underwent CAG., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Cardiological Society of India. Published by Elsevier, a division of RELX India, Pvt. Ltd. All rights reserved.)
- Published
- 2023
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6. Comprehensive protein tyrosine phosphatase mRNA profiling identifies new regulators in the progression of glioma.
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Bourgonje AM, Verrijp K, Schepens JT, Navis AC, Piepers JA, Palmen CB, van den Eijnden M, Hooft van Huijsduijnen R, Wesseling P, Leenders WP, and Hendriks WJ
- Subjects
- Brain Neoplasms pathology, CRISPR-Cas Systems, Cell Line, Tumor, Cell Movement physiology, Disease Progression, Gene Expression Profiling, Gene Expression Regulation, Neoplastic, Glioma genetics, Glioma pathology, HEK293 Cells, Humans, Immunohistochemistry, Isocitrate Dehydrogenase genetics, Isocitrate Dehydrogenase metabolism, Kaplan-Meier Estimate, Neoplasm Grading, PTEN Phosphohydrolase deficiency, PTEN Phosphohydrolase genetics, Protein Tyrosine Phosphatases genetics, RNA, Messenger metabolism, Real-Time Polymerase Chain Reaction, Reverse Transcriptase Polymerase Chain Reaction, Brain Neoplasms enzymology, Glioma enzymology, Protein Tyrosine Phosphatases metabolism
- Abstract
The infiltrative behavior of diffuse gliomas severely reduces therapeutic potential of surgical resection and radiotherapy, and urges for the identification of new drug-targets affecting glioma growth and migration. To address the potential role of protein tyrosine phosphatases (PTPs), we performed mRNA expression profiling for 91 of the 109 known human PTP genes on a series of clinical diffuse glioma samples of different grades and compared our findings with in silico knowledge from REMBRANDT and TCGA databases. Overall PTP family expression levels appeared independent of characteristic genetic aberrations associated with lower grade or high grade gliomas. Notably, seven PTP genes (DUSP26, MTMR4, PTEN, PTPRM, PTPRN2, PTPRT and PTPRZ1) were differentially expressed between grade II-III gliomas and (grade IV) glioblastomas. For DUSP26, PTEN, PTPRM and PTPRT, lower expression levels correlated with poor prognosis, and overexpression of DUSP26 or PTPRT in E98 glioblastoma cells reduced tumorigenicity. Our study represents the first in-depth analysis of PTP family expression in diffuse glioma subtypes and warrants further investigations into PTP-dependent signaling events as new entry points for improved therapy.
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- 2016
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7. One-Tube-Only Standardized Site-Directed Mutagenesis: An Alternative Approach to Generate Amino Acid Substitution Collections.
- Author
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Mingo J, Erramuzpe A, Luna S, Aurtenetxe O, Amo L, Diez I, Schepens JT, Hendriks WJ, Cortés JM, and Pulido R
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- DNA Primers metabolism, Escherichia coli genetics, Escherichia coli metabolism, Gene Expression, Humans, PTEN Phosphohydrolase genetics, PTEN Phosphohydrolase metabolism, Plasmids chemistry, Plasmids metabolism, Receptor-Like Protein Tyrosine Phosphatases, Class 5 genetics, Receptor-Like Protein Tyrosine Phosphatases, Class 5 metabolism, Software, Amino Acid Substitution, DNA Primers genetics, Mutagenesis, Site-Directed methods, Mutation, Polymerase Chain Reaction methods
- Abstract
Site-directed mutagenesis (SDM) is a powerful tool to create defined collections of protein variants for experimental and clinical purposes, but effectiveness is compromised when a large number of mutations is required. We present here a one-tube-only standardized SDM approach that generates comprehensive collections of amino acid substitution variants, including scanning- and single site-multiple mutations. The approach combines unified mutagenic primer design with the mixing of multiple distinct primer pairs and/or plasmid templates to increase the yield of a single inverse-PCR mutagenesis reaction. Also, a user-friendly program for automatic design of standardized primers for Ala-scanning mutagenesis is made available. Experimental results were compared with a modeling approach together with stochastic simulation data. For single site-multiple mutagenesis purposes and for simultaneous mutagenesis in different plasmid backgrounds, combination of primer sets and/or plasmid templates in a single reaction tube yielded the distinct mutations in a stochastic fashion. For scanning mutagenesis, we found that a combination of overlapping primer sets in a single PCR reaction allowed the yield of different individual mutations, although this yield did not necessarily follow a stochastic trend. Double mutants were generated when the overlap of primer pairs was below 60%. Our results illustrate that one-tube-only SDM effectively reduces the number of reactions required in large-scale mutagenesis strategies, facilitating the generation of comprehensive collections of protein variants suitable for functional analysis., Competing Interests: The authors have declared that no competing interests exist.
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- 2016
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8. Identification of a novel inactivating mutation in Isocitrate Dehydrogenase 1 (IDH1-R314C) in a high grade astrocytoma.
- Author
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van Lith SA, Navis AC, Lenting K, Verrijp K, Schepens JT, Hendriks WJ, Schubert NA, Venselaar H, Wevers RA, van Rooij A, Wesseling P, Molenaar RJ, van Noorden CJ, Pusch S, Tops B, and Leenders WP
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- Animals, Base Sequence, Binding Sites, Cell Line, Tumor, Glutarates metabolism, HEK293 Cells, Heterozygote, Humans, Isocitrates metabolism, Mice, NADP metabolism, Neoplasm Grading, Protein Multimerization, Astrocytoma enzymology, Astrocytoma genetics, Brain Neoplasms enzymology, Brain Neoplasms genetics, Isocitrate Dehydrogenase genetics, Mutation genetics
- Abstract
The majority of low-grade and secondary high-grade gliomas carry heterozygous hotspot mutations in cytosolic isocitrate dehydrogenase 1 (IDH1) or the mitochondrial variant IDH2. These mutations mostly involve Arg132 in IDH1, and Arg172 or Arg140 in IDH2. Whereas IDHs convert isocitrate to alpha-ketoglutarate (α-KG) with simultaneous reduction of NADP(+) to NADPH, these IDH mutants reduce α-KG to D-2-hydroxyglutarate (D-2-HG) while oxidizing NADPH. D-2-HG is a proposed oncometabolite, acting via competitive inhibition of α-KG-dependent enzymes that are involved in metabolism and epigenetic regulation. However, much less is known about the implications of the metabolic stress, imposed by decreased α-KG and NADPH production, for tumor biology. We here present a novel heterozygous IDH1 mutation, IDH1(R314C), which was identified by targeted next generation sequencing of a high grade glioma from which a mouse xenograft model and a cell line were generated. IDH1(R314C) lacks isocitrate-to-α-KG conversion activity due to reduced affinity for NADP(+), and differs from the IDH1(R132) mutants in that it does not produce D-2-HG. Because IDH1(R314C) is defective in producing α-KG and NADPH, without concomitant production of the D-2-HG, it represents a valuable tool to study the effects of IDH1-dysfunction on cellular metabolism in the absence of this oncometabolite.
- Published
- 2016
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9. Comment on Authenticity and traceability of vanilla flavors by analysis of stable isotopes of carbon and hydrogen.
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Greule M, Mosandl A, Hamilton JT, and Keppler F
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- Flavoring Agents analysis, Food Contamination analysis, Plant Extracts analysis, Vanilla chemistry
- Published
- 2015
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10. PTEN-PDZ domain interactions: binding of PTEN to PDZ domains of PTPN13.
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Sotelo NS, Schepens JT, Valiente M, Hendriks WJ, and Pulido R
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- Amino Acid Sequence, Humans, Molecular Sequence Data, PTEN Phosphohydrolase genetics, Protein Interaction Domains and Motifs physiology, Protein Structure, Secondary, Protein Tyrosine Phosphatase, Non-Receptor Type 13 genetics, Tumor Suppressor Proteins genetics, PDZ Domains physiology, PTEN Phosphohydrolase metabolism, Protein Tyrosine Phosphatase, Non-Receptor Type 13 metabolism, Tumor Suppressor Proteins metabolism
- Abstract
Protein modular interactions mediated by PDZ domains are essential for the establishment of functional protein networks controlling diverse cellular functions. The tumor suppressor PTEN possesses a C-terminal PDZ-binding motif (PDZ-BM) that is recognized by a specific set of PDZ domains from scaffolding and regulatory proteins. Here, we review the current knowledge on PTEN-PDZ domain interactions and tumor suppressor networks, describe methodology suitable to analyze these interactions, and report the binding of PTEN and the PDZ domain-containing protein tyrosine phosphatase PTPN13. Yeast two-hybrid and GST pull-down analyses showed that PTEN binds to PDZ2/PTPN13 domain in a manner that depends on the specific PTPN13 PDZ domain arrangement involving the interdomain region between PDZ1 and PDZ2. Furthermore, a specific binding profile of PTEN to PDZ2/PTPN13 domain was observed by mutational analysis of the PTEN PDZ-BM. Our results disclose a PDZ-mediated physical interaction of PTEN and PTPN13 with potential relevance in tumor suppression and cell homeostasis., (Copyright © 2014 Elsevier Inc. All rights reserved.)
- Published
- 2015
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11. Chloromethane release from carbonaceous meteorite affords new insight into Mars lander findings.
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Keppler F, Harper DB, Greule M, Ott U, Sattler T, Schöler HF, and Hamilton JT
- Abstract
Controversy continues as to whether chloromethane (CH3Cl) detected during pyrolysis of Martian soils by the Viking and Curiosity Mars landers is indicative of organic matter indigenous to Mars. Here we demonstrate CH3Cl release (up to 8 μg/g) during low temperature (150-400°C) pyrolysis of the carbonaceous chondrite Murchison with chloride or perchlorate as chlorine source and confirm unequivocally by stable isotope analysis the extraterrestrial origin of the methyl group (δ(2)H +800 to +1100‰, δ(13)C -19.2 to +10‰,). In the terrestrial environment CH3Cl released during pyrolysis of organic matter derives from the methoxyl pool. The methoxyl pool in Murchison is consistent both in magnitude (0.044%) and isotope signature (δ(2)H +1054 ± 626‰, δ(13)C +43.2 ± 38.8‰,) with that of the CH3Cl released on pyrolysis. Thus CH3Cl emissions recorded by Mars lander experiments may be attributed to methoxyl groups in undegraded organic matter in meteoritic debris reaching the Martian surface being converted to CH3Cl with perchlorate or chloride in Martian soil. However we cannot discount emissions arising additionally from organic matter of indigenous origin. The stable isotope signatures of CH3Cl detected on Mars could potentially be utilized to determine its origin by distinguishing between terrestrial contamination, meteoritic infall and indigenous Martian sources.
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- 2014
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12. Intracellular and extracellular domains of protein tyrosine phosphatase PTPRZ-B differentially regulate glioma cell growth and motility.
- Author
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Bourgonje AM, Navis AC, Schepens JT, Verrijp K, Hovestad L, Hilhorst R, Harroch S, Wesseling P, Leenders WP, and Hendriks WJ
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- Animals, Brain Neoplasms genetics, Brain Neoplasms pathology, Cell Line, Tumor, Female, Gene Expression Regulation, Enzymologic, Gene Expression Regulation, Neoplastic, Gene Knockdown Techniques, Glioma genetics, Glioma pathology, Humans, Mice, Inbred BALB C, Mice, Nude, Phenotype, Protein Structure, Tertiary, Receptor-Like Protein Tyrosine Phosphatases, Class 5 genetics, Signal Transduction, Transfection, Brain Neoplasms enzymology, Cell Movement, Cell Proliferation, Glioma enzymology, Receptor-Like Protein Tyrosine Phosphatases, Class 5 metabolism
- Abstract
Gliomas are primary brain tumors for which surgical resection and radiotherapy is difficult because of the diffuse infiltrative growth of the tumor into the brain parenchyma. For development of alternative, drug-based, therapies more insight in the molecular processes that steer this typical growth and morphodynamic behavior of glioma cells is needed. Protein tyrosine phosphatase PTPRZ-B is a transmembrane signaling molecule that is found to be strongly up-regulated in glioma specimens. We assessed the contribution of PTPRZ-B protein domains to tumor cell growth and migration, via lentiviral knock-down and over-expression using clinically relevant glioma xenografts and their derived cell models. PTPRZ-B knock-down resulted in reduced migration and proliferation of glioma cells in vitro and also inhibited tumor growth in vivo. Interestingly, expression of only the PTPRZ-B extracellular segment was sufficient to rescue the in vitro migratory phenotype that resulted from PTPRZ-B knock-down. In contrast, PTPRZ-B knock-down effects on proliferation could be reverted only after re-expression of PTPRZ-B variants that contained its C-terminal PDZ binding domain. Thus, distinct domains of PTPRZ-B are differentially required for migration and proliferation of glioma cells, respectively. PTPRZ-B signaling pathways therefore represent attractive therapeutic entry points to combat these tumors.
- Published
- 2014
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13. The Encyclopedia of Life v2: Providing Global Access to Knowledge About Life on Earth.
- Author
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Parr CS, Wilson N, Leary P, Schulz KS, Lans K, Walley L, Hammock JA, Goddard A, Rice J, Studer M, Holmes JT, and Corrigan RJ Jr
- Abstract
The Encyclopedia of Life (EOL, http://eol.org) aims to provide unprecedented global access to a broad range of information about life on Earth. It currently contains 3.5 million distinct pages for taxa and provides content for 1.3 million of those pages. The content is primarily contributed by EOL content partners (providers) that have a more limited geographic, taxonomic or topical scope. EOL aggregates these data and automatically integrates them based on associated scientific names and other classification information. EOL also provides interfaces for curation and direct content addition. All materials in EOL are either in the public domain or licensed under a Creative Commons license. In addition to the web interface, EOL is also accessible through an Application Programming Interface. In this paper, we review recent developments added for Version 2 of the web site and subsequent releases through Version 2.2, which have made EOL more engaging, personal, accessible and internationalizable. We outline the core features and technical architecture of the system. We summarize milestones achieved so far by EOL to present results of the current system implementation and establish benchmarks upon which to judge future improvements. We have shown that it is possible to successfully integrate large amounts of descriptive biodiversity data from diverse sources into a robust, standards-based, dynamic, and scalable infrastructure. Increasing global participation and the emergence of EOL-powered applications demonstrate that EOL is becoming a significant resource for anyone interested in biological diversity.
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- 2014
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14. Kinetics of the atrazine degradation process using H2O2-UVC.
- Author
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Sarmento SM and Miranda JT
- Subjects
- Kinetics, Atrazine chemistry, Herbicides chemistry, Hydrogen Peroxide chemistry, Water Pollutants, Chemical chemistry
- Abstract
This work is concerned with the intrinsic reaction kinetic of the degradation of atrazine (ATZ) using H2O2-UVC. Experimental runs were carried out in annular photoreactor. The initial concentration of ATZ was 2.2 × 10(-2) mol m(-3) while the H2O2-ATZ molar ratio range was 0-578 mol H2O2 mol(-1) ATZ. The ATZ molecules are decomposed by means of free-radical attack (95.2%) and direct photolysis (4.8%). There is an optimal H2O2/ATZ molar ratio (ROP = 347 H2O2 mol(-1) ATZ) which maximizes the initial degradation rate and conversion at 300 s at 83% and 77%, respectively. The process is economically feasible as the values of the energy requirement, energy and H2O2 costs at ROP are 0.14 KWh m(-3) order(-1), US$0.02 kWh(-1) m(-3) and US$1.0 m(-3), respectively. The kinetic model proposed is based on Lea's reaction scheme for the H2O2 direct photolysis, the hypothesis that unknown ATZ sub-products that absorb UVC radiation are generated, and the local volumetric rate of photon absorption. The radiation transport equation was solved and the linear spherical source emission model was used to represent the lamp emission. Intrinsic reaction kinetic parameters were estimated and the model was validated. The model predicted the data in a range of 90 to 98%.
- Published
- 2014
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15. Ultraviolet (UVB and UVA) photoprotector activity and percutaneous penetration of extracts obtained from Arrabidaea chica.
- Author
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Siraichi JT, Pedrochi F, Natali MR, Ueda-Nakamura T, Filho BP, Bento AC, Baesso ML, and Nakamura CV
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- Analysis of Variance, Animals, Blood Cell Count, Blood Cells drug effects, Male, Photoacoustic Techniques, Plant Extracts chemistry, Rabbits, Skin chemistry, Skin pathology, Skin Absorption drug effects, Spectrophotometry, Ultraviolet, Sunscreening Agents chemistry, Ultraviolet Rays, Bignoniaceae chemistry, Plant Extracts pharmacology, Skin drug effects, Skin radiation effects, Sunscreening Agents pharmacology
- Abstract
The aim of this work is to investigate the photoprotection activity and toxicity level of formulations containing the extract and its fractions obtained from leaves of Arrabidaea chica. The ex vivo percutaneous penetration of the extract was evaluated using the photoacoustic spectroscopy technique. The formulation presented optical absorption in the ultraviolet region, including UVA and UVB. This formulation was obtained without adding inorganic UV filters, as is frequently used in commercial sunscreens. The results showed a penetration rate similar to those of commercial sunscreens with its presence on the skin surface at least 180 min after the application. This formulation presented no toxic effects evaluated using hematological, biochemical, and histological assays. The results suggest that the formulation from the leaves of A. chica provides substantial protection against UVA + UVB radiation with a possible advantage of being natural and free of inorganic compounds compared with the majority of available commercial sunscreens.
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- 2013
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16. Serotonin 1A receptors alter expression of movement representations.
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Scullion K, Boychuk JA, Yamakawa GR, Rodych JT, Nakanishi ST, Seto A, Smith VM, McCarthy RW, Whelan PJ, Antle MC, Pittman QJ, and Teskey GC
- Subjects
- 5,7-Dihydroxytryptamine pharmacology, 8-Hydroxy-2-(di-n-propylamino)tetralin pharmacology, Action Potentials drug effects, Action Potentials genetics, Analysis of Variance, Animals, Brain Mapping, Chromatography, High Pressure Liquid, Forelimb drug effects, Forelimb physiology, H-Reflex drug effects, H-Reflex genetics, Male, Mice, Mice, Knockout, Microinjections, Motor Cortex drug effects, Motor Cortex physiology, Movement drug effects, Neurons drug effects, Neurons physiology, Patch-Clamp Techniques, Piperazines pharmacology, Psychomotor Performance drug effects, Raphe Nuclei cytology, Raphe Nuclei drug effects, Rats, Rats, Long-Evans, Receptor, Serotonin, 5-HT1A deficiency, Serotonin deficiency, Serotonin Agents pharmacology, Spinal Cord drug effects, Spinal Cord physiology, Tryptophan Hydroxylase metabolism, Movement physiology, Receptor, Serotonin, 5-HT1A metabolism
- Abstract
Serotonin has a myriad of central functions involving mood, appetite, sleep, and memory and while its release within the spinal cord is particularly important for generating movement, the corresponding role on cortical movement representations (motor maps) is unknown. Using adult rats we determined that pharmacological depletion of serotonin (5-HT) via intracerebroventricular administration of 5,7 dihydroxytryptamine resulted in altered movements of the forelimb in a skilled reaching task as well as higher movement thresholds and smaller maps derived using high-resolution intracortical microstimulation (ICMS). We ruled out the possibility that reduced spinal cord excitability could account for the serotonin depletion-induced changes as we observed an enhanced Hoffman reflex (H-reflex), indicating a hyperexcitable spinal cord. Motor maps derived in 5-HT1A receptor knock-out mice also showed higher movement thresholds and smaller maps compared with wild-type controls. Direct cortical application of the 5-HT1A/7 agonist 8-OH-DPAT lowered movement thresholds in vivo and increased map size in 5-HT-depleted rats. In rats, electrical stimulation of the dorsal raphe lowered movement thresholds and this effect could be blocked by direct cortical application of the 5-HT1A antagonist WAY-100135, indicating that serotonin is primarily acting through the 5-HT1A receptor. Next we developed a novel in vitro ICMS preparation that allowed us to track layer V pyramidal cell excitability. Bath application of WAY-100135 raised the ICMS current intensity to induce action potential firing whereas the agonist 8-OH-DPAT had the opposite effect. Together our results demonstrate that serotonin, acting through 5-HT1A receptors, plays an excitatory role in forelimb motor map expression.
- Published
- 2013
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17. Barcoded cDNA library preparation for small RNA profiling by next-generation sequencing.
- Author
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Hafner M, Renwick N, Farazi TA, Mihailović A, Pena JT, and Tuschl T
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- Base Sequence, Gene Expression Profiling methods, Humans, RNA, Small Interfering chemistry, RNA, Small Interfering genetics, Sequence Analysis, RNA methods, Gene Library, High-Throughput Nucleotide Sequencing methods, MicroRNAs chemistry, MicroRNAs genetics, Specimen Handling
- Abstract
The characterization of post-transcriptional gene regulation by small regulatory (20-30 nt) RNAs, particularly miRNAs and piRNAs, has become a major focus of research in recent years. A prerequisite for characterizing small RNAs is their identification and quantification across different developmental stages, and in normal and disease tissues, as well as model cell lines. Here we present a step-by-step protocol for generating barcoded small RNA cDNA libraries compatible with Illumina HiSeq sequencing, thereby facilitating miRNA and other small RNA profiling of large sample collections., (Copyright © 2012 Elsevier Inc. All rights reserved.)
- Published
- 2012
- Full Text
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18. Bacterial dioxygenase- and monooxygenase-catalysed sulfoxidation of benzo[b]thiophenes.
- Author
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Boyd DR, Sharma ND, McMurray B, Haughey SA, Allen CC, Hamilton JT, McRoberts WC, O'Ferrall RA, Nikodinovic-Runic J, Coulombel LA, and O'Connor KE
- Subjects
- Crystallography, X-Ray, Oxidation-Reduction, Sulfoxides chemistry, Thiophenes chemistry, Dioxygenases metabolism, Escherichia coli enzymology, Multienzyme Complexes metabolism, Oxygenases metabolism, Pseudomonas putida enzymology, Sulfoxides metabolism, Thiophenes metabolism
- Abstract
Asymmetric heteroatom oxidation of benzo[b]thiophenes to yield the corresponding sulfoxides was catalysed by toluene dioxygenase (TDO), naphthalene dioxygenase (NDO) and styrene monooxygenase (SMO) enzymes present in P. putida mutant and E. coli recombinant whole cells. TDO-catalysed oxidation yielded the relatively unstable benzo[b]thiophene sulfoxide; its dimerization, followed by dehydrogenation, resulted in the isolation of stable tetracyclic sulfoxides as minor products with cis-dihydrodiols being the dominant metabolites. SMO mainly catalysed the formation of enantioenriched benzo[b]thiophene sulfoxide and 2-methyl benzo[b]thiophene sulfoxides which racemized at ambient temperature. The barriers to pyramidal sulfur inversion of 2- and 3-methyl benzo[b]thiophene sulfoxide metabolites, obtained using TDO and NDO as biocatalysts, were found to be ca.: 25-27 kcal mol(-1). The absolute configurations of the benzo[b]thiophene sulfoxides were determined by ECD spectroscopy, X-ray crystallography and stereochemical correlation. A site-directed mutant E. coli strain containing an engineered form of NDO, was found to change the regioselectivity toward preferential oxidation of the thiophene ring rather than the benzene ring.
- Published
- 2012
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19. Evidence of Methylobacterium spp. and Hyphomicrobium sp. in azaspiracid toxin contaminated mussel tissues and assessment of the effect of azaspiracid on their growth.
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Nzoughet JK, Grant IR, Prodöhl PA, Hamilton JT, Botana LM, and Elliott CT
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- Animals, Chromatography, High Pressure Liquid, Hyphomicrobium drug effects, Hyphomicrobium growth & development, Marine Toxins pharmacology, Methylobacterium drug effects, Methylobacterium growth & development, Microbial Viability drug effects, Mytilus edulis chemistry, Spiro Compounds pharmacology, Tandem Mass Spectrometry, Foodborne Diseases microbiology, Hyphomicrobium isolation & purification, Marine Toxins analysis, Methylobacterium isolation & purification, Mytilus edulis microbiology, Spiro Compounds analysis
- Abstract
A flagellar protein belonging to the genus Methylobacterium or Agrobacterium was previously observed by proteomics in azaspiracids (AZA) toxic mussels. Here, we report the isolation of two different Methylobacterium spp. (NTx1 and Tx1) from non-toxic and AZA toxic mussels, respectively, which when co-cultured with AZA exhibited significantly different growth responses - isolate Tx1 growth rate was enhanced, whereas growth of isolate NTx1 was adversely affected, compared to non-AZA supplemented control cultures. A Hyphomicrobium sp. (Tx2) also isolated from the toxic mussels achieved greater cell density in AZAs supplemented cultures., (Copyright © 2011 Elsevier Ltd. All rights reserved.)
- Published
- 2011
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20. Initial studies on the occurrence of cyanobacteria and microcystins in Irish lakes.
- Author
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Mooney KM, Hamilton JT, Floyd SD, Foy RH, and Elliott CT
- Subjects
- Ireland, Microcystins analysis, Microcystis growth & development, Cyanobacteria growth & development, Lakes, Microcystins isolation & purification
- Abstract
We report the results of a synoptic survey at 14 sites across the north of Ireland undertaken to determine the occurrence of cyanobacteria and their constituent microcystin cyanotoxins. Seven microcystin toxins were tested for, and five of which were found, with MC-LR, MC-RR, and MC-YR being the most prevalent. Gomphosphaeria spp and Microcystis aeruginosa were the most dominant cyanobacterial species encountered. Together with Aphanizomenon flos-aquae, these were the cyanobacteria associated with the highest microcystin concentrations. The occurrence of several microcystin toxins indicates that there may potentially be more than one cyanobacteria species producing microcystins at many sites. Total microcystin concentrations varied over three orders of magnitude dividing the sites into two groups of high (>1000 ngMC/μgChla, six sites) or low toxicity (<200 ngMC/μgChla, eight sites)., (Copyright © 2010 Wiley Periodicals, Inc.)
- Published
- 2011
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21. RNA-ligase-dependent biases in miRNA representation in deep-sequenced small RNA cDNA libraries.
- Author
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Hafner M, Renwick N, Brown M, Mihailović A, Holoch D, Lin C, Pena JT, Nusbaum JD, Morozov P, Ludwig J, Ojo T, Luo S, Schroth G, and Tuschl T
- Subjects
- DNA Primers, Gene Expression Profiling methods, Multigene Family, Oligonucleotides genetics, Polymerase Chain Reaction, RNA Ligase (ATP) analysis, Sequence Analysis, RNA, Gene Library, High-Throughput Nucleotide Sequencing methods, MicroRNAs analysis, RNA Ligase (ATP) genetics
- Abstract
Sequencing of small RNA cDNA libraries is an important tool for the discovery of new RNAs and the analysis of their mutational status as well as expression changes across samples. It requires multiple enzyme-catalyzed steps, including sequential oligonucleotide adapter ligations to the 3' and 5' ends of the small RNAs, reverse transcription (RT), and PCR. We assessed biases in representation of miRNAs relative to their input concentration, using a pool of 770 synthetic miRNAs and 45 calibrator oligoribonucleotides, and tested the influence of Rnl1 and two variants of Rnl2, Rnl2(1-249) and Rnl2(1-249)K227Q, for 3'-adapter ligation. The use of the Rnl2 variants for adapter ligations yielded substantially fewer side products compared with Rnl1; however, the benefits of using Rnl2 remained largely obscured by additional biases in the 5'-adapter ligation step; RT and PCR steps did not have a significant impact on read frequencies. Intramolecular secondary structures of miRNA and/or miRNA/3'-adapter products contributed to these biases, which were highly reproducible under defined experimental conditions. We used the synthetic miRNA cocktail to derive correction factors for approximation of the absolute levels of individual miRNAs in biological samples. Finally, we evaluated the influence of 5'-terminal 5-nt barcode extensions for a set of 20 barcoded 3' adapters and observed similar biases in miRNA read distribution, thereby enabling cost-saving multiplex analysis for large-scale miRNA profiling.
- Published
- 2011
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22. MicroRNA-24 regulates vascularity after myocardial infarction.
- Author
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Fiedler J, Jazbutyte V, Kirchmaier BC, Gupta SK, Lorenzen J, Hartmann D, Galuppo P, Kneitz S, Pena JT, Sohn-Lee C, Loyer X, Soutschek J, Brand T, Tuschl T, Heineke J, Martin U, Schulte-Merker S, Ertl G, Engelhardt S, Bauersachs J, and Thum T
- Subjects
- Animals, Apoptosis drug effects, Arterioles pathology, Capillaries pathology, Cell Hypoxia, Cells, Cultured drug effects, Cells, Cultured metabolism, Collagen, Drug Combinations, Drug Evaluation, Preclinical, Endothelial Cells pathology, GATA2 Transcription Factor biosynthesis, GATA2 Transcription Factor genetics, Gene Expression Profiling, Heart Failure etiology, Heme Oxygenase-1 biosynthesis, Heme Oxygenase-1 genetics, Laminin, Male, Mice, Mice, Inbred C57BL, MicroRNAs antagonists & inhibitors, MicroRNAs genetics, Myocardial Infarction complications, Myocardial Infarction genetics, Neovascularization, Physiologic drug effects, Neovascularization, Physiologic genetics, Oligoribonucleotides pharmacology, Proteoglycans, RNA Interference, RNA, Small Interfering pharmacology, RNA, Small Interfering therapeutic use, Spheroids, Cellular, Ventricular Remodeling, Zebrafish embryology, Zebrafish Proteins biosynthesis, Zebrafish Proteins genetics, p21-Activated Kinases biosynthesis, p21-Activated Kinases genetics, Endothelial Cells metabolism, MicroRNAs physiology, Myocardial Infarction physiopathology
- Abstract
Background: Myocardial infarction leads to cardiac remodeling and development of heart failure. Insufficient myocardial capillary density after myocardial infarction has been identified as a critical event in this process, although the underlying mechanisms of cardiac angiogenesis are mechanistically not well understood., Methods and Results: Here, we show that the small noncoding RNA microRNA-24 (miR-24) is enriched in cardiac endothelial cells and considerably upregulated after cardiac ischemia. MiR-24 induces endothelial cell apoptosis, abolishes endothelial capillary network formation on Matrigel, and inhibits cell sprouting from endothelial spheroids. These effects are mediated through targeting of the endothelium-enriched transcription factor GATA2 and the p21-activated kinase PAK4, which were identified by bioinformatic predictions and validated by luciferase gene reporter assays. Respective downstream signaling cascades involving phosphorylated BAD (Bcl-XL/Bcl-2-associated death promoter) and Sirtuin1 were identified by transcriptome, protein arrays, and chromatin immunoprecipitation analyses. Overexpression of miR-24 or silencing of its targets significantly impaired angiogenesis in zebrafish embryos. Blocking of endothelial miR-24 limited myocardial infarct size of mice via prevention of endothelial apoptosis and enhancement of vascularity, which led to preserved cardiac function and survival., Conclusions: Our findings indicate that miR-24 acts as a critical regulator of endothelial cell apoptosis and angiogenesis and is suitable for therapeutic intervention in the setting of ischemic heart disease.
- Published
- 2011
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23. Dioxygenase-catalysed cis-dihydroxylation of meta-substituted phenols to yield cyclohexenone cis-diol and derived enantiopure cis-triol metabolites.
- Author
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Boyd DR, Sharma ND, Stevenson PJ, Blain M, McRoberts C, Hamilton JT, Argudo JM, Mundi H, Kulakov LA, and Allen CC
- Subjects
- Cyclohexanols metabolism, Cyclohexanones metabolism, Hydroxylation, Models, Molecular, Molecular Structure, Oxidation-Reduction, Phenols metabolism, Stereoisomerism, Substrate Specificity, Biocatalysis, Cyclohexanols chemistry, Cyclohexanones chemistry, Dioxygenases metabolism, Phenols chemistry
- Abstract
cis-Dihydroxylation of meta-substituted phenol (m-phenol) substrates, to yield the corresponding cyclohexenone cis-diol metabolites, was catalysed by arene dioxygenases present in mutant and recombinant bacterial strains. The presence of cyclohexenone cis-diol metabolites and several of their cyclohexene and cyclohexane cis-triol derivatives was detected by LC-TOFMS analysis and confirmed by NMR spectroscopy. Structural and stereochemical analyses of chiral ketodiol bioproducts, was carried out using NMR and CD spectroscopy and stereochemical correlation methods. The formation of enantiopure cyclohexenone cis-diol metabolites is discussed in the context of postulated binding interactions of the m-phenol substrates at the active site of toluene dioxygenase (TDO).
- Published
- 2011
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24. Effects of spermidine and p-cresol on polymorphonuclear cell apoptosis and function.
- Author
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de Carvalho JT Jr, Dalboni MA, Watanabe R, Peres AT, Goes MA, Manfredi SR, Canziani ME, Cendoroglo GS, Guimarães-Souza N, Batista MC, and Cendoroglo M
- Subjects
- Humans, Neutrophils cytology, Neutrophils immunology, Neutrophils metabolism, Apoptosis drug effects, CD11b Antigen immunology, Cresols pharmacology, Neutrophils drug effects, Reactive Oxygen Species metabolism, Spermidine pharmacology
- Abstract
Polymorphonuclear leukocytes (PMNs) from chronic kidney disease (CKD) patients display accelerated apoptosis and dysfunction, which may predispose CKD patients to infections. In this study, we investigated the effect of spermidine and p-cresol on apoptosis and function on PMN from healthy subjects. We measured the effect of spermidine and p-cresol on apoptosis, ROS production unstimulated and stimulated (S. aureus and PMA) and expression of CD95, caspase 3, and CD11b on PMN. After incubation with p-cresol and spermidine, we did not observe any changes in apoptosis, viability or expression of caspase 3 and CD95 in PMN from healthy subjects. PMN incubated for 10 minutes with spermidine demonstrated a significant reduction in spontaneous, S. aureus and PMA-stimulated ROS production. p-cresol induced a decrease in PMA-stimulated ROS production. Spermidine and p-cresol also induced a decrease in the expression of CD11b on PMN. Spermidine and p-cresol decreased the expression of CD11b and oxidative burst of PMN from healthy subjects and had no effect on PMN apoptosis and viability., (© 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.)
- Published
- 2011
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25. Chemoenzymatic synthesis of chiral 2,2'-bipyridine ligands and their N-oxide derivatives: applications in the asymmetric aminolysis of epoxides and asymmetric allylation of aldehydes.
- Author
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Boyd DR, Sharma ND, Sbircea L, Murphy D, Malone JF, James SL, Allen CC, and Hamilton JT
- Subjects
- 2,2'-Dipyridyl chemical synthesis, Aldehydes chemistry, Biotransformation, Epoxy Compounds chemistry, Ligands, Oxides chemical synthesis, Pseudomonas putida enzymology, Sphingomonas enzymology, 2,2'-Dipyridyl chemistry, Oxides chemistry, Quinolines metabolism
- Abstract
A series of enantiopure 2,2'-bipyridines have been synthesised from the corresponding cis-dihydrodiol metabolites of 2-chloroquinolines. Several of the resulting hydroxylated 2,2'-bipyridines were found to be useful chiral ligands for the asymmetric aminolysis of meso-epoxides leading to the formation of enantioenriched amino alcohols (-->84% ee). N-oxide and N,N'-dioxide derivatives of these 2,2'-bipyridines, including separable atropisomers, have been synthesised and used as enantioselective organocatalysts in the asymmetric allylation of aldehydes to give allylic alcohols (-->86% ee).
- Published
- 2010
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26. Differential regulation of mature and precursor microRNA expression by NMDA and metabotropic glutamate receptor activation during LTP in the adult dentate gyrus in vivo.
- Author
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Wibrand K, Panja D, Tiron A, Ofte ML, Skaftnesmo KO, Lee CS, Pena JT, Tuschl T, and Bramham CR
- Subjects
- Animals, Dactinomycin pharmacology, Dentate Gyrus physiology, Gene Expression Regulation drug effects, Indans pharmacology, Long-Term Potentiation drug effects, Long-Term Potentiation physiology, Male, Piperazines pharmacology, Rats, Rats, Sprague-Dawley, Receptors, Metabotropic Glutamate antagonists & inhibitors, Receptors, N-Methyl-D-Aspartate antagonists & inhibitors, Dentate Gyrus metabolism, Gene Expression Regulation physiology, Long-Term Potentiation genetics, MicroRNAs metabolism, Receptors, Metabotropic Glutamate physiology, Receptors, N-Methyl-D-Aspartate physiology
- Abstract
Regulation of microRNA (miRNA) expression and function in the context of activity-dependent synaptic plasticity in the adult brain is little understood. Here, we examined miRNA expression during long-term potentiation (LTP) in the dentate gyrus of adult anesthetized rats. Microarray expression profiling identified a subpopulation of regulated mature miRNAs 2 h after the induction of LTP by high-frequency stimulation (HFS) of the medial perforant pathway. Real-time polymerase chain reaction analysis confirmed modest upregulation of miR-132 and miR-212, and downregulation of miR-219, while no changes occurred at 10 min post-HFS. Surprisingly, pharmacological blockade of N-methyl-d-aspartate receptor (NMDAR)-dependent LTP enhanced expression of these mature miRNAs. This HFS-evoked expression was abolished by local infusion of the group 1 metabotropic glutamate receptor (mGluR) antagonist, (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA). AIDA had no effect on LTP induction or maintenance, but blocked activity-dependent depotentiation of LTP. Turning to the analysis of miRNA precursors, we show that HFS elicits 50-fold elevations of primary (pri) and precursor (pre) miR-132/212 that is transcription dependent and mGluR dependent, but insensitive to NMDAR blockade. Primary miR-219 expression was unchanged during LTP. In situ hybridization showed upregulation of the pri-miR-132/212 cluster restricted to dentate granule cell somata. Thus, HFS induces transcription miR-132/212 that is mGluR dependent and functionally correlated with depotentiation rather than LTP. In contrast, NMDAR activation selectively downregulates mature miR-132, -212 and -219 levels, indicating accelerated decay of these mature miRNAs. This study demonstrates differential regulation of primary and mature miRNA expression by mGluR and NMDAR signaling following LTP induction, the function of which remains to be defined.
- Published
- 2010
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27. Protein tyrosine phosphatases in glioma biology.
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Navis AC, van den Eijnden M, Schepens JT, Hooft van Huijsduijnen R, Wesseling P, and Hendriks WJ
- Subjects
- Animals, Humans, Brain Neoplasms enzymology, Glioma enzymology, Protein Tyrosine Phosphatases metabolism, Signal Transduction physiology
- Abstract
Gliomas are a diverse group of brain tumors of glial origin. Most are characterized by diffuse infiltrative growth in the surrounding brain. In combination with their refractive nature to chemotherapy this makes it almost impossible to cure patients using combinations of conventional therapeutic strategies. The drastically increased knowledge about the molecular underpinnings of gliomas during the last decade has elicited high expectations for a more rational and effective therapy for these tumors. Most studies on the molecular pathways involved in glioma biology thus far had a strong focus on growth factor receptor protein tyrosine kinase (PTK) and phosphatidylinositol phosphatase signaling pathways. Except for the tumor suppressor PTEN, much less attention has been paid to the PTK counterparts, the protein tyrosine phosphatase (PTP) superfamily, in gliomas. PTPs are instrumental in the reversible phosphorylation of tyrosine residues and have emerged as important regulators of signaling pathways that are linked to various developmental and disease-related processes. Here, we provide an overview of the current knowledge on PTP involvement in gliomagenesis. So far, the data point to the potential implication of receptor-type (RPTPdelta, DEP1, RPTPmicro, RPTPzeta) and intracellular (PTP1B, TCPTP, SHP2, PTPN13) classical PTPs, dual-specific PTPs (MKP-1, VHP, PRL-3, KAP, PTEN) and the CDC25B and CDC25C PTPs in glioma biology. Like PTKs, these PTPs may represent promising targets for the development of novel diagnostic and therapeutic strategies in the treatment of high-grade gliomas.
- Published
- 2010
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28. Monitoring of environmental contamination by Echinococcus multilocularis in an urban fringe forest park in Hokkaido, Japan.
- Author
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Lagapa JT, Oku Y, Kaneko M, Ganzorig S, Ono T, Nonaka N, Kobayashi F, and Kamiya M
- Abstract
Objectives: The aim of this study was to determine the prevalence of Echinococcus multilocularis environmental contamination in an urban fringe-the Nopporo forest park of Sapporo city, Hokkaido, Japan. A secondary aim was to determine possible transmission risks areas by associating percentage occurrence of E. multilocularis-positive faeces with the different land-use classes., Methods: Wild fox faeces collected from the environment were examined by intravital methods, such as the taeniid egg sucrose floatation technique, E. multilocularis coproantigen enzyme-linked immunosorbent analysis and DNA test of taeniid eggs by PCR. Geospatial maps produced by the Global Positioning System and Landsat data were analysed using geographic information system software to determine the association between percentage occurrences of E. multilocularis-positive fox faeces and land-use classes., Results: Our findings showed high prevalence rates in both E. multilocularis egg and coproantigen-positive faeces (16 and 49%, respectively) in the investigated urban fringe forest park. Data revealed that percentage occurrence of E. multilocularis-positive fox faeces was associated with land-use classes, such as forest and open field (P < 0.05)., Conclusions: We conclude that Nopporo forest park in the urban fringe of Sapporo city, Hokkaido is a reservoir with a high prevalence of zoonotic infective agents for alveolar echinococcosis. Our findings suggest that interface habitats between forests or woodlands and open fields are indispensable for continued maintenance of the life-cycle of E. multilocularis and, as such, constitute high risk areas for echinococcosis transmission.
- Published
- 2009
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29. Proteomics identification of azaspiracid toxin biomarkers in blue mussels, Mytilus edulis.
- Author
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Nzoughet JK, Hamilton JT, Botting CH, Douglas A, Devine L, Nelson J, and Elliott CT
- Subjects
- Amino Acid Sequence, Animals, Biomarkers analysis, Biomarkers metabolism, Electrophoresis, Polyacrylamide Gel, Hepatopancreas metabolism, Marine Toxins metabolism, Proteins metabolism, Spectrometry, Mass, Electrospray Ionization, Spiro Compounds metabolism, Marine Toxins analysis, Mytilus edulis metabolism, Proteins analysis, Proteomics methods, Spiro Compounds analysis
- Abstract
Azaspiracids are a class of recently discovered algae-derived shellfish toxins. Their distribution globally is on the increase with mussels being most widely implicated in azaspiracid-related food poisoning events. Evidence that these toxins were bound to proteins in contaminated mussels has been shown recently. In the present study characterization of these proteins in blue mussels, Mytilus edulis, was achieved using a range of advanced proteomics tools. Four proteins present only in the hepatopancreas of toxin-contaminated mussels sharing identity or homology with cathepsin D, superoxide dismutase, glutathione S-transferase Pi, and a bacterial flagellar protein have been characterized. Several of the proteins are known to be involved in self-defense mechanisms against xenobiotics or up-regulated in the presence of carcinogenic agents. These findings would suggest that azaspiracids should now be considered and evaluated as potential tumorigenic compounds. The presence of a bacterial protein only in contaminated mussels was an unexpected finding and requires further investigation. The proteins identified in this study should assist with development of urgently required processes for the rapid depuration of azaspiracid-contaminated shellfish. Moreover they may serve as early warning indicators of shellfish exposed to this family of toxins.
- Published
- 2009
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30. Effect of phosphate binders on oxidative stress and inflammation markers in hemodialysis patients.
- Author
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Peres AT, Dalboni MA, Canziani ME, Manfredi SR, Carvalho JT, Batista MC, Cuppari L, Carvalho AB, Moyses RM, Guimarães N, Jorgetti V, Andreoli MC, Draibe SA, and Cendoroglo M
- Subjects
- Acetates therapeutic use, Adult, Biomarkers blood, Calcium Compounds therapeutic use, Female, Humans, Inflammation drug therapy, Male, Middle Aged, Polyamines therapeutic use, Reactive Oxygen Species metabolism, Sevelamer, Treatment Outcome, Inflammation blood, Inflammation Mediators blood, Oxidative Stress drug effects, Phosphate-Binding Proteins therapeutic use, Renal Dialysis adverse effects
- Abstract
It has been suggested that phosphate binders may reduce the inflammatory state of hemodialysis (HD) patients. However, it is not clear whether it has any effect on oxidative stress. The objective of this study was to evaluate the effect of sevelamer hydrochloride (SH) and calcium acetate (CA) on oxidative stress and inflammation markers in HD patients. Hemodialysis patients were randomly assigned to therapy with SH (n=17) or CA (n=14) for 1 year. Before the initiation of therapy (baseline) and at 12 months, we measured in vitro reactive oxygen species (ROS) production by stimulated and unstimulated polymorphonuclear neutrophils and serum levels of tumor necrosis factor alpha, interleukin-10, C-reactive protein, and albumin. There was a significant reduction of spontaneous ROS production in both groups after 12 months of therapy. There was a significant decrease of Staphylococcus aureus stimulated ROS production in the SH group. There was a significant increase in albumin serum levels only in the SH group. In the SH group, there was also a decrease in the serum levels of tumor necrosis factor alpha and C-reactive protein. Our results suggest that compared with CA treatment, SH may lead to a reduction in oxidative stress and inflammation. Therefore, it is possible that phosphate binders exert pleiotropic effects on oxidative stress and inflammation, which could contribute toward decreasing endothelial injury in patients in HD.
- Published
- 2009
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31. A simple rapid method to precisely determine (13)C/(12)C ratios of plant methoxyl groups.
- Author
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Greule M, Mosandl A, Hamilton JT, and Keppler F
- Subjects
- Chromatography, Gas methods, Mass Spectrometry methods, Benzaldehydes analysis, Carbon analysis, Carbon Isotopes analysis, Fraxinus chemistry, Lignin analysis, Pectins analysis
- Abstract
Stable isotope ratios of individual plant components have become a valuable tool for the determination of the geographical origin and authenticity of foodstuff. A recently published method with considerable potential in this context is the measurement of the deuterium/hydrogen (D/H) isotope ratios of plant matter methoxyl groups. The method entailed cleavage of methyl ethers or esters with hydriodic acid (HI) to form gaseous methyl iodide (CH(3)I) and then measurement of the delta(2)H value of this gas. Here, as a follow up to a previous study, we describe a method for the rapid and precise delta(13)C analysis of plant matter methoxyl groups using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Conditions for sample preparation were investigated for isotope discrimination effects, the GC conditions optimized, the reproducibility of the measurement of standards undertaken, and the precision of the method defined. The reproducibility of the delta(13)C value determined for a CH(3)I standard on 20 consecutive measurements was found to be 0.17 per thousand. The method was also tested on four methoxyl-rich plant components: vanillin, lignin, wood and pectin. The analytical precision obtained, expressed as the average standard deviation, for these compounds was found to be better than 0.13 per thousand. The described procedure which is simple and rapid, allowing preparation and analysis of a sample within 1 h, produces accurate and reproducible isotopic measurements. We suggest that this validated delta(13)C method when employed together with the recently published delta(2)H method for two-dimensional stable isotope studies of organic matter containing methoxyl groups will be of considerable value, e.g. for proving the authenticity of foodstuff., (Copyright (c) 2009 John Wiley & Sons, Ltd.)
- Published
- 2009
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32. miRNA in situ hybridization in formaldehyde and EDC-fixed tissues.
- Author
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Pena JT, Sohn-Lee C, Rouhanifard SH, Ludwig J, Hafner M, Mihailovic A, Lim C, Holoch D, Berninger P, Zavolan M, and Tuschl T
- Subjects
- Animals, Brain cytology, Brain metabolism, Brain Chemistry, Mice, MicroRNAs genetics, Microscopy, Fluorescence methods, Neurons cytology, Neurons metabolism, Carbodiimides chemistry, Formaldehyde chemistry, In Situ Hybridization methods, MicroRNAs analysis, Tissue Fixation methods
- Abstract
MicroRNAs are small regulatory RNAs with many biological functions and disease associations. We showed that in situ hybridization (ISH) using conventional formaldehyde fixation results in substantial microRNA loss from mouse tissue sections, which can be prevented by fixation with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide that irreversibly immobilizes the microRNA at its 5' phosphate. We determined optimal hybridization parameters for 130 locked nucleic acid probes by recording nucleic acid melting temperature during ISH.
- Published
- 2009
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33. In vitro reconstituted biotransformation of 4-fluorothreonine from fluoride ion: application of the fluorinase.
- Author
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Deng H, Cross SM, McGlinchey RP, Hamilton JT, and O'Hagan D
- Subjects
- Amino Acid Sequence, Bacterial Proteins genetics, Biotransformation, Fluorides metabolism, Fructose-Bisphosphate Aldolase chemistry, Fructose-Bisphosphate Aldolase genetics, Fructose-Bisphosphate Aldolase metabolism, Molecular Sequence Data, Molecular Structure, Oxidoreductases genetics, Sequence Alignment, Streptomyces classification, Streptomyces genetics, Threonine chemistry, Threonine metabolism, Transaldolase chemistry, Transaldolase genetics, Transaldolase metabolism, Up-Regulation, Bacterial Proteins metabolism, Fluorides chemistry, Oxidoreductases metabolism, Streptomyces enzymology, Threonine analogs & derivatives
- Abstract
In this paper, we report that fluoride ion is converted to the amino acid/antibiotic 4-fluorothreonine 2 in a biotransformation involving five (steps a-e) overexpressed enzymes. The biotransformation validates the biosynthetic pathway to 4-fluorothreonine in the bacterium Streptomyces cattleya (Schaffrath et al., 2002). To achieve an in vitro biotransformation, the fluorinase and the purine nucleoside phosphorylase (PNP) enzymes (steps a and b), which are coded for by the flA and flB genes of the fluorometabolite gene cluster in S. cattleya, were overexpressed. Also, an isomerase gene product that can convert 5-FDRP 6 to 5-FDRibulP 7 (step c) was identified in S. cattleya, and the enzyme was overexpressed for the biotransformation. A fuculose aldolase gene from S. coelicolor was overexpressed in E. coli and was used as a surrogate aldolase (step d) in these experiments. To complete the complement of enzymes, an ORF coding the PLP-dependent transaldolase, the final enzyme of the fluorometabolite pathway, was identified in genomic DNA by a reverse genetics approach, and the S. cattleya gene/enzyme was then overexpressed in S. lividans. This latter enzyme is an unusual PLP-dependent catalyst with some homology to both bacterial serine hydroxymethyl transferases (SHMT) and C5 sugar isomerases/epimerases. The biotransformation demonstrates the power of the fluorinase to initiate C-F bond formation for organo-fluorine synthesis.
- Published
- 2008
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34. Tracing the geographical origin of early potato tubers using stable hydrogen isotope ratios of methoxyl groups.
- Author
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Keppler F and Hamilton JT
- Subjects
- Europe, Geography, Germany, Isotope Labeling methods, Mediterranean Region, Deuterium, Solanum tuberosum growth & development
- Abstract
The application of stable isotope ratio measurements has become an extremely useful tool for tracing the provenance of food products, thus ensuring that consumers receive products which comply with their labelled specifications. Recently, it has been shown that relative stable hydrogen isotope abundances (delta(2)H values) of wood lignin methoxyl groups have a distinct range that reflects the delta(2)H values of their meteoric source water. Furthermore, it has been suggested that the isotope information stored in methoxyl groups in plant matter generally might assist with determining the place of origin of plant material. We now have measured delta(2)H values of methoxyl groups from natural compounds in tubers of early potatoes (Solanum tuberosum) grown in different geographical locations. Tubers of early potatoes were collected from across Europe and regions close to the Mediterranean Sea between April and July 2004. The methoxyl groups from the potatoes were found to be highly depleted in (2)H, relative to both their meteoric water and bulk biomass, and a systematic shift of the delta(2)H values between methoxyl groups and meteoric water was observed. A constant fractionation of-161+/-11 per thousand. between methoxyl groups and modelled meteoric water is shown over a transaction covering the delta(2)H values of meteoric water from-95 per thousand in Northern Sweden to+25 per thousand in Egypt. From this information, early potato tubers from Middle Europe can be clearly distinguished from those of Mediterranean regions and from Northern Europe. Thus, we suggest that delta(2)H values of methoxyl groups have the potential to become an effective tool in assisting with the constraint of the geographical origin of potato tubers and other food stuffs.
- Published
- 2008
- Full Text
- View/download PDF
35. A rapid and precise method for determination of D/H ratios of plant methoxyl groups.
- Author
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Greule M, Mosandl A, Hamilton JT, and Keppler F
- Subjects
- Benzaldehydes chemistry, Benzaldehydes metabolism, Esterification, Lignin chemistry, Lignin metabolism, Pectins chemistry, Pectins metabolism, Plant Extracts analysis, Plants metabolism, Reproducibility of Results, Wood chemistry, Wood metabolism, Deuterium analysis, Gas Chromatography-Mass Spectrometry methods, Plant Extracts chemistry, Plants chemistry
- Abstract
Stable hydrogen isotope ratio measurements of specific plant components are increasingly used in numerous fields of research, including sample origin verification and climate research. A recently suggested method with considerable potential in this context is the D/H isotope ratio (delta(2)H value) analysis of plant matter methoxyl groups. The method entails ether or ester cleavage with hydriodic acid (HI) to form the gaseous compound methyl iodide (CH(3)I) and measurement of the delta(2)H value of this gas. Here we describe a method for the rapid and precise delta(2)H analysis of plant matter methoxyl groups using gas chromatography/pyrolysis/isotope ratio mass spectrometry (GC/P/IRMS). The conditions for sample preparation were investigated for isotope discrimination effects, the GC conditions were optimized, the reproducibility of the measurement of standards was studied, and the precision of the method was defined. The reproducibility of delta(2)H values determined for a CH(3)I standard on 20 consecutive measurements was found to be 2 per thousand. The method was also tested on four methoxyl-rich plant components: vanillin, lignin, wood and pectin. The analytical precision obtained, when expressed as the average standard deviation for these compounds, was better than 1.6 per thousand. The described method is rapid, allowing preparation and analysis of a sample within 1 h, and produces accurate and reproducible isotopic measurements., (Copyright 2008 John Wiley & Sons, Ltd.)
- Published
- 2008
- Full Text
- View/download PDF
36. Azaarene cis-dihydrodiol-derived 2,2'-bipyridine ligands for asymmetric allylic oxidation and cyclopropanation.
- Author
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Boyd DR, Sharma ND, Sbircea L, Murphy D, Belhocine T, Malone JF, James SL, Allen CC, and Hamilton JT
- Subjects
- 2,2'-Dipyridyl chemical synthesis, Alkenes chemistry, Allyl Compounds chemistry, Aza Compounds chemical synthesis, Catalysis, Crystallography, X-Ray, Cyclization, Cyclopropanes chemistry, Dioxygenases chemistry, Ligands, Models, Molecular, Molecular Structure, Naphthalenes chemical synthesis, Oxidation-Reduction, Stereoisomerism, 2,2'-Dipyridyl chemistry, Allyl Compounds chemical synthesis, Aza Compounds chemistry, Cyclopropanes chemical synthesis, Naphthalenes chemistry
- Abstract
Biphenyl dioxygenase-catalysed cis-dihydroxylation of 2-chloroquinoline, 2-chloro-3-methylquinoline and 2-chloro-6-phenylpyridine substrates yielded the corresponding enantiopure cis-dihydrodiols; enantiopure 2,2'-bipyridines, synthesised in four steps from 2-chloroquinoline, proved to be efficient chiral ligands in catalytic asymmetric allylic oxidation and cyclopropanation reactions of alkenes.
- Published
- 2008
- Full Text
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37. Regioselectivity and stereoselectivity of dioxygenase catalysed cis-dihydroxylation of mono- and tri-cyclic azaarene substrates.
- Author
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Boyd DR, Sharma ND, Coen GP, Hempenstall F, Ljubez V, Malone JF, Allen CC, and Hamilton JT
- Subjects
- Benzene chemistry, Benzene metabolism, Biocatalysis, Dioxygenases chemistry, Dioxygenases genetics, Hydroxylation, Mutagenesis, Site-Directed, Phenanthrenes chemistry, Phenanthrenes metabolism, Stereoisomerism, Substrate Specificity, Aza Compounds chemistry, Aza Compounds metabolism, Dioxygenases metabolism
- Abstract
cis-Dihydrodiol metabolites were obtained from dioxygenase-catalysed asymmetric dihydroxylations of five monocyclic (azabiphenyl) and four tricyclic (azaphenanthrene) azaarene substrates. Enantiopurity values and absolute configuration assignments were determined using a combination of stereochemical correlation, X-ray crystallography and spectroscopy methods. The degree of regioselectivity found during cis-dihydroxylation of monocyclic azaarenes (2,3 bond >> 3,4 bond) and of tricyclic azaarenes (bay region > non-bay region bonds) was dependent on the type of dioxygenase used. The cis-dihydrodiol metabolite from an azaarene (3-phenylpyridine) was utilised in the chemoenzymatic synthesis of the corresponding trans-dihydrodiol.
- Published
- 2008
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38. Abiotic methyl bromide formation from vegetation, and its strong dependence on temperature.
- Author
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Wishkerman A, Gebhardt S, McRoberts CW, Hamilton JT, Williams J, and Keppler F
- Subjects
- Bromine metabolism, Chlorine metabolism, Desiccation, Environment, Fraxinus chemistry, Kinetics, Solanum lycopersicum chemistry, Methyl Chloride analysis, Pectins chemistry, Plant Leaves chemistry, Thermodynamics, Volatilization, Water chemistry, Hydrocarbons, Brominated analysis, Plants chemistry, Temperature
- Abstract
Methyl bromide (CH3Br) is the most abundant brominated organic compound in the atmosphere. It is known to originate from natural and anthropogenic sources, although many uncertainties remain regarding strengths of both sources and sinks and the processes leading to its formation. In this study a potential new CH3Br source from vegetation has been examined, analogous to the recently discovered abiotic formation of methyl chloride from plant pectin. Several plant samples with known bromine content, including ash (Fraxinus excelsior), saltwort (Batis maritima), tomato reference material (NIST-1573a), hay reference material (IAEA V-10), and also bromine enriched pectin, were incubated in the temperature range of 25-50 degrees C and analyzed for CH3Br emission using gas chromatography/mass spectrometry. All plant samples inspected showed an exponential increase in CH3Br emission as a function of temperature increase, i.e., emissions were observed to approximately double with every 5 degrees C rise in temperature. Next to temperature, it was found that emissions of CH3Br were also dependent on the bromine content of the plants. The highest CH3Br release rates were found for the saltwort which contained the highest bromine concentration. Arrhenius plots confirmed that the observed emissions were from an abiotic origin. The contribution of abiotic CH3Br formation from vegetation to the global budget will vary geographically as a result of regional differences in both temperature and bromide content of terrestrial plants.
- Published
- 2008
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39. The multi-vicinal fluoroalkane motif: an examination of 2,3,4,5-tetrafluorohexane stereoisomers.
- Author
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Hunter L, Kirsch P, Hamilton JT, and O'Hagan D
- Subjects
- Crystallography, X-Ray, Fluorine Compounds chemistry, Hexanes chemistry, Models, Molecular, Molecular Conformation, Molecular Structure, Naphthalenes chemistry, Photochemistry, Pyrans chemistry, Stereoisomerism, Sulfones chemistry, Ultraviolet Rays, Fluorine Compounds chemical synthesis, Hexanes chemical synthesis, Naphthalenes chemical synthesis
- Abstract
Three unique diastereoisomers of 2,3,4,5-tetrafluorohexane have been prepared, compounds intermediate between hexane and perfluorohexane in their degree of fluorination, and they show very different conformational behaviour and physical properties.
- Published
- 2008
- Full Text
- View/download PDF
40. Azaspiracid: first evidence of protein binding in shellfish.
- Author
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Nzoughet KJ, Hamilton JT, Floyd SD, Douglas A, Nelson J, Devine L, and Elliott CT
- Subjects
- Animals, Biomarkers chemistry, Chromatography, High Pressure Liquid, Electrophoresis, Polyacrylamide Gel, Environmental Monitoring, Hepatopancreas chemistry, Hepatopancreas metabolism, Isoelectric Focusing, Marine Toxins analysis, Protein Binding, Proteins chemistry, Spiro Compounds analysis, Tandem Mass Spectrometry, Food Contamination analysis, Foodborne Diseases, Marine Toxins metabolism, Mytilus edulis chemistry, Proteins metabolism, Shellfish, Spiro Compounds metabolism
- Abstract
The occurrence of azaspiracid (AZA) toxins in contaminated shellfish has been the focus of much research. The present study investigated the binding properties of these toxins in mussels of the species Mytilus edulis. The work involved extraction of proteins and AZAs from contaminated mussel hepatopancreas and examination of the extracts by isoelectric focusing (IEF), size exclusion chromatography (SEC) and sodium docecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Liquid chromatography coupled with tandem mass spectrometry analysis (LC-MS/MS) was also performed in this study to identify AZAs. Blank mussels were subjected to the same purification and analytical procedures. AZAs were found to be weakly bound to a protein with a molecular weight of 45 kDa, in samples of contaminated mussels. This protein, which was abundant in contaminated mussels, was also present in blank mussels, albeit at much lower concentrations. It was further noted that a 22 kDa protein was also present only in contaminated mussel samples.
- Published
- 2008
- Full Text
- View/download PDF
41. Enzyme-catalysed synthesis and reactions of benzene oxide/oxepine derivatives of methyl benzoates.
- Author
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Boyd DR, Sharma ND, Harrison JS, Malone JF, McRoberts WC, Hamilton JT, and Harper DB
- Subjects
- Catalysis, Crystallography, X-Ray, Cyclization, Hydrolysis, Molecular Structure, Oxepins chemistry, Stereoisomerism, Triazoles chemistry, Benzoates chemistry, Cyclohexanes chemistry, Oxepins chemical synthesis
- Abstract
A series of twelve benzoate esters was metabolised, by species of the Phellinus genus of wood-rotting fungi, to yield the corresponding benzyl alcohol derivatives and eight salicylates. The isolation of a stable oxepine metabolite, from methyl benzoate, allied to evidence of the migration and retention of a carbomethoxy group (the NIH Shift), during enzyme-catalysed ortho-hydroxylation of alkyl benzoates to form salicylates, is consistent with a mechanism involving an initial arene epoxidation step. This mechanism was confirmed by the isolation of a remarkably stable, optically active, substituted benzene oxide metabolite of methyl 2-(trifluoromethyl)benzoate, which slowly converted into the racemic form. The arene oxide was found to undergo a cycloaddition reaction with 4-phenyl-1,2,4-triazoline-3,5-dione to yield a crystalline cycloadduct whose structure and racemic nature was established by X-ray crystallography. The metabolite was also found to undergo some novel benzene oxide reactions, including epoxidation to give an anti-diepoxide, base-catalysed hydrolysis to form a trans-dihydrodiol and acid-catalysed aromatisation to yield a salicylate derivative via the NIH Shift of a carbomethoxy group.
- Published
- 2008
- Full Text
- View/download PDF
42. Multimerisation of receptor-type protein tyrosine phosphatases PTPBR7 and PTP-SL attenuates enzymatic activity.
- Author
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Noordman YE, Augustus ED, Schepens JT, Chirivi RG, Ríos P, Pulido R, and Hendriks WJ
- Subjects
- Animals, COS Cells, Chlorocebus aethiops, HeLa Cells, Humans, Hydrophobic and Hydrophilic Interactions, Immune Sera, Membrane Proteins chemistry, Membrane Proteins metabolism, Mice, Protein Isoforms chemistry, Protein Isoforms metabolism, Protein Structure, Quaternary, Protein Structure, Tertiary, Receptor-Like Protein Tyrosine Phosphatases, Class 7 chemistry, Receptor-Like Protein Tyrosine Phosphatases, Class 7 metabolism
- Abstract
Dimerisation of receptor-type protein tyrosine phosphatases (RPTPs) represents an appealing mechanism to regulate their enzymatic activity. Studies thus far mostly concern the dimerisation behaviour of RPTPs possessing two tandemly oriented catalytic PTP domains. Mouse gene Ptprr encodes four different protein isoforms (i.e. PTPBR7, PTP-SL and PTPPBSgamma-42/37) that contain a single PTP domain. Using selective membrane permeabilisation we here demonstrate that PTP-SL, like PTPBR7, is a single membrane-spanning RPTP. Furthermore, these two receptor-type PTPs constitutively formed homo- and hetero-meric complexes as witnessed in chemical cross-linking and co-immunoprecipitation experiments, in sharp contrast to the cytosolic PTPPBSgamma-42 and PTPPBSgamma-37 PTPRR isoforms. This multimerisation occurs independently of the PTP domain and requires the transmembrane domain and/or the proximal hydrophobic region. Using overexpression of a PTPBR7 mutant that essentially lacks the intracellular PTP domain-containing segment, a monomer-mimicking state was forced upon full-length PTPBR7 immunoprecipitates. This resulted in a significant increase in the enzymatic activity of the PTPRR PTP domain, which strengthens the notion that multimerisation represents a general mechanism to tone down RPTP catalytic activity.
- Published
- 2008
- Full Text
- View/download PDF
43. S-adenosyl-L-methionine:hydroxide adenosyltransferase: a SAM enzyme.
- Author
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Deng H, Botting CH, Hamilton JT, Russell RJ, and O'Hagan D
- Subjects
- Adenosine metabolism, Catalysis, Methionine metabolism, Archaea enzymology, Methionine Adenosyltransferase metabolism
- Published
- 2008
- Full Text
- View/download PDF
44. The identification of (3R,4S)-5-fluoro-5-deoxy-D-ribulose-1-phosphate as an intermediate in fluorometabolite biosynthesis in Streptomyces cattleya.
- Author
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Onega M, McGlinchey RP, Deng H, Hamilton JT, and O'Hagan D
- Subjects
- Aldose-Ketose Isomerases chemistry, Bacterial Proteins chemistry, Biosynthetic Pathways, Catalysis, Cell-Free System, Fluoroacetates chemistry, Gas Chromatography-Mass Spectrometry, Magnetic Resonance Spectroscopy, Models, Chemical, Oxidoreductases chemistry, Phosphorylases metabolism, Protein Isoforms, Streptomyces metabolism, Ribulosephosphates chemistry, Streptomyces chemistry
- Abstract
(3R,4S)-5-Fluoro-5-deoxy-D-ribulose-1-phosphate (5-FDRulP) has been identified as the third fluorinated intermediate on the biosynthetic pathway to fluoroacetate and 4-fluorothreonine in Streptomyces cattleya. 5-FDRulP is generated after formation of 5'-fluoro-5'-deoxyadenosine (5'-FDA) and then phosphorolysis of 5'-FDA to 5-fluoro-5-deoxy-D-ribose-1-phosphate (5-FDRP) by the action of a purine nucleoside phosphorylase. An isomerase mediates the conversion of 5-FDRP to 5-FDRulP. The identity of the (3R,4S) diastereoisomer of 5-FDRulP was established by comparative (19)F{(1)H} NMR studies whereby 5-FDRulP that accumulated in a cell free extract of S. cattleya, was treated with a phytase to generate the non-phosphorylated sugar, 5-fluoro-5-deoxy-D-ribulose (5-FDRul). This S. cattleya product was compared to the product of an in-vitro biotransformation where separately 5-fluoro-5-deoxy-D-ribose and 5-fluoro-5-deoxy-D-xylose were converted to 5-fluoro-5-deoxy-D-ribulose and 5-fluoro-5-deoxy-D-xylulose respectively by the action of glucose isomerase. It was demonstrated that 5-fluoro-5-deoxy-D-ribose gave the identical diastereoisomer to that observed from 5-FDRulP.
- Published
- 2007
- Full Text
- View/download PDF
45. Synthesis, structure and stereochemistry of quinoline alkaloids from Choisya ternata.
- Author
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Boyd DR, Sharma ND, Loke PL, Malone JF, McRoberts WC, and Hamilton JT
- Subjects
- Alkaloids isolation & purification, Crystallography, X-Ray, Magnetic Resonance Spectroscopy, Spectrometry, Mass, Electrospray Ionization, Stereoisomerism, Alkaloids chemical synthesis, Alkaloids chemistry, Rutaceae chemistry
- Abstract
A range of seventeen quinoline alkaloids, involving several types of oxidations during their biosynthetic pathways, have been isolated from leaves of Choisya ternata. In addition to the nine known quinoline alkaloids, eight new members of the furoquinoline family, derived mainly from prenylation at C-5 (including two novel hydroperoxides), have been identified. The absolute configurations and enantiopurity values of all chiral quinoline alkaloids have been determined. One of the isolated alkaloids, 7-isopentenyloxy-gamma-fagarine, has been used as a precursor for the chemical asymmetric synthesis of the enantiopure alkaloids: evoxine, anhydroevoxine and evodine. The possible roles of oxygenase and other oxygen-atom-transfer enzymes, in the biosynthetic pathways of the C. ternata alkaloids, have been discussed.
- Published
- 2007
- Full Text
- View/download PDF
46. Current control strategies targeting sources of echinococcosis in Japan.
- Author
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Kamiya M, Lagapa JT, Nonaka N, Ganzorig S, Oku Y, and Kamiya H
- Subjects
- Animals, Animals, Domestic, Animals, Wild, Anthelmintics therapeutic use, Communicable Disease Control methods, Dog Diseases epidemiology, Dog Diseases prevention & control, Dog Diseases transmission, Dogs, Echinococcosis epidemiology, Echinococcosis prevention & control, Humans, Japan epidemiology, Public Health, Echinococcosis transmission, Echinococcosis veterinary, Echinococcus multilocularis pathogenicity, Foxes parasitology, Zoonoses
- Abstract
The authors describe the current control strategies targeting definitive hosts of the most important zoonotic parasite in Japan, Echinococcus multilocularis. A dramatic increase in the prevalence of echinococcosis in foxes in Hokkaido (the second largest of Japan's islands), the invasion of wild foxes into urban areas, infection among pet and stray dogs, and the possibility of spreading the disease to the main island of Japan (Honshu)--all these pose significant threats to public health. Previous research findings and current strategies such as control measures against infections in wild foxes, suggest that it will be possible to eliminate echinococcosis in the future. The enforcement of a national reporting system for veterinarians, international collaboration, and the establishment of a Forum on Environment and Animals (FEA) give further reason to believe that success is possible. This is the first report of a multifaceted control strategy against echinococcosis in definitive hosts that includes collaborative efforts with local residents. This model might provide new ideas for Veterinary Services worldwide in their efforts to control other related zoonotic diseases.
- Published
- 2006
47. Shark rectal gland vasoactive intestinal peptide receptor: cloning, functional expression, and regulation of CFTR chloride channels.
- Author
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Bewley MS, Pena JT, Plesch FN, Decker SE, Weber GJ, and Forrest JN Jr
- Subjects
- Amino Acid Sequence, Animals, Cell Cycle Proteins metabolism, Chlorides metabolism, Cloning, Molecular, Conserved Sequence, Cystic Fibrosis Transmembrane Conductance Regulator genetics, Endodeoxyribonucleases metabolism, Gene Expression Regulation, In Vitro Techniques, Male, Molecular Sequence Data, Oocytes physiology, Patch-Clamp Techniques, Phylogeny, Reverse Transcriptase Polymerase Chain Reaction, Vasoactive Intestinal Peptide pharmacology, Xenopus laevis, Cystic Fibrosis Transmembrane Conductance Regulator metabolism, Dogfish physiology, Receptors, Vasoactive Intestinal Peptide genetics, Receptors, Vasoactive Intestinal Peptide metabolism, Salt Gland physiology
- Abstract
Vasoactive intestinal peptide (VIP) is a secretagogue that mediates chloride secretion in intestinal epithelia. We determined the relative potency of VIP and related peptides in the rectal gland of the elasmobranch dogfish shark and cloned and expressed the VIP receptor (sVIP-R) from this species. In the perfused rectal gland, VIP (5 nM) stimulated chloride secretion from 250 +/- 66 to 2,604 +/- 286 microeq x h(-1) x g(-1); the relative potency of peptide agonists was VIP > PHI = GHRH > PACAP > secretin, where PHI is peptide histidine isoleucine amide, GHRH is growth hormone-releasing hormone, and PACAP is pituitary adenylate cylase activating peptide. The cloned sVIP-R from shark rectal gland (SRG) is only 61% identical to the human VIP-R1. It maintains a long, extracellular NH2 terminus with seven cysteine residues, and has three N-glycosylation sites and eight other residues implicated in VIP binding. Two amino acids considered important for peptide binding in mammals are not present in the shark orthologue. When sVIP-R and the CFTR chloride channel were coexpressed in Xenopus oocytes, VIP increased chloride conductance from 11.3 +/- 2 to 127 +/- 34 microS. The agonist affinity for activating chloride conductance by the cloned receptor was VIP > GHRH = PHI > PACAP > secretin, a profile mirroring that in the perfused gland. The receptor differs from previously cloned VIP-Rs in having a low affinity for PACAP. Expression of both sVIP-R and CFTR mRNA was detected by quantitative PCR in shark rectal gland, intestine, and brain. These studies characterize a unique G protein-coupled receptor from the shark rectal gland that is the oldest cloned VIP-R.
- Published
- 2006
- Full Text
- View/download PDF
48. Task switching as a two-stage decision process.
- Author
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Sinha N, Brown JT, and Carpenter RH
- Subjects
- Adult, Female, Humans, Male, Photic Stimulation methods, Probability, Psychomotor Performance physiology, Time Factors, Decision Making physiology, Models, Psychological, Reaction Time physiology, Saccades physiology
- Abstract
Saccades represent decisions, and the study of their latency has led to a neurally plausible model of the underlying mechanisms, LATER (Linear Approach to Threshold with Ergodic Rate), that can successfully predict reaction time behavior in simple decision tasks, with fixed instructions. However, if the instructions abruptly change, we have a more complex situation, known as task switching. Psychologists' explanations of the phenomena of task switching have so far tended to be qualitative rather than quantitative, and not intended to relate particularly clearly to existing models of decision making or to likely neural implementations. Here, we investigated task switching using a novel saccadic task: we presented the instructions by stimulus elements identical to those of the task itself, allowing us to compare decisions about instructions with decisions in the actual task. Our results support a relatively simple model consisting of two distinct LATER processes in series: the first detects the instruction, the second implements it.
- Published
- 2006
- Full Text
- View/download PDF
49. Methane emissions from terrestrial plants under aerobic conditions.
- Author
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Keppler F, Hamilton JT, Brass M, and Röckmann T
- Subjects
- Aerobiosis, Atmosphere chemistry, Biomass, Carbon Isotopes, Darkness, Greenhouse Effect, Methane analysis, Plant Leaves metabolism, Methane metabolism, Oxygen metabolism, Plants metabolism
- Abstract
Methane is an important greenhouse gas and its atmospheric concentration has almost tripled since pre-industrial times. It plays a central role in atmospheric oxidation chemistry and affects stratospheric ozone and water vapour levels. Most of the methane from natural sources in Earth's atmosphere is thought to originate from biological processes in anoxic environments. Here we demonstrate using stable carbon isotopes that methane is readily formed in situ in terrestrial plants under oxic conditions by a hitherto unrecognized process. Significant methane emissions from both intact plants and detached leaves were observed during incubation experiments in the laboratory and in the field. If our measurements are typical for short-lived biomass and scaled on a global basis, we estimate a methane source strength of 62-236 Tg yr(-1) for living plants and 1-7 Tg yr(-1) for plant litter (1 Tg = 10(12) g). We suggest that this newly identified source may have important implications for the global methane budget and may call for a reconsideration of the role of natural methane sources in past climate change.
- Published
- 2006
- Full Text
- View/download PDF
50. De novo formation of chloroethyne in soil.
- Author
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Keppler F, Borchers R, Hamilton JT, Kilian G, Pracht J, and Schöler HF
- Subjects
- Alkynes chemistry, Biotransformation, Chlorine chemistry, Ethyl Chloride analogs & derivatives, Ferric Compounds chemistry, Germany, Hydrogen Peroxide chemistry, Industrial Waste, Oxidation-Reduction, Tetrachloroethylene chemistry, Trichloroethylene chemistry, Volatilization, Alkynes analysis, Ecosystem, Ethyl Chloride analysis, Soil Pollutants analysis
- Abstract
To date, chloroethyne in the environment has been proposed to occur as a reactive intermediate during the reductive dechlorination of tri- and tetrachloroethene with zerovalent metals. Such artificial conditions might possibly be found at organohalide-contaminated sites that are surrounded by remediation barriers made of metallic iron. In this paper, it is shown that the highly reactive chloroethyne is also a product of natural processes in soil. Soil air samples from three differentterrestrial ecosystems of Northern Germany showed significant chloroethyne concentrations, besides other naturally produced monochlorinated compounds, such as chloromethane, chloroethane and chloroethene. Measured amounts range from 5 to 540 pg chloroethyne in air purged from 1 L of soil. A possible route of chloroethyne formation in soil is discussed, where chloroethyne is probably produced as a byproduct of the oxidative halogenation of aromatic compounds in soil. A series of laboratory studies, using the redox-sensitive catechol as a discrete organic model compound, showed the formation of chloroethyne when Fe3+ and hydrogen peroxide were added to the system. We therefore propose that the natural formation of chloroethyne in soil proceeds via oxidative cleavage of a quinonic system in the presence of the ubiquitous soil component chloride.
- Published
- 2006
- Full Text
- View/download PDF
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