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Harris JA, Liu R, Martins de Oliveira V, Vázquez-Montelongo EA, Henderson JA, Shen J. GPU-Accelerated All-Atom Particle-Mesh Ewald Continuous Constant pH Molecular Dynamics in Amber. J Chem Theory Comput 2022; 18:7510-7527. [PMID: 36377980 PMCID: PMC10130738 DOI: 10.1021/acs.jctc.2c00586] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Constant pH molecular dynamics (MD) simulations sample protonation states on the fly according to the conformational environment and user specified pH conditions; however, the current accuracy is limited due to the use of implicit-solvent models or a hybrid solvent scheme. Here, we report the first GPU-accelerated implementation, parametrization, and validation of the all-atom continuous constant pH MD (CpHMD) method with particle-mesh Ewald (PME) electrostatics in the Amber22 pmemd.cuda engine. The titration parameters for Asp, Glu, His, Cys, and Lys were derived for the CHARMM c22 and Amber ff14sb and ff19sb force fields. We then evaluated the PME-CpHMD method using the asynchronous pH replica-exchange titration simulations with the c22 force field for six benchmark proteins, including BBL, hen egg white lysozyme (HEWL), staphylococcal nuclease (SNase), thioredoxin, ribonuclease A (RNaseA), and human muscle creatine kinase (HMCK). The root-mean-square deviation from the experimental pKa's of Asp, Glu, His, and Cys is 0.76 pH units, and the Pearson's correlation coefficient for the pKa shifts with respect to model values is 0.80. We demonstrated that a finite-size correction or much enlarged simulation box size can remove a systematic error of the calculated pKa's and improve agreement with experiment. Importantly, the simulations captured the relevant biology in several challenging cases, e.g., the titration order of the catalytic dyad Glu35/Asp52 in HEWL and the coupled residues Asp19/Asp21 in SNase, the large pKa upshift of the deeply buried catalytic Asp26 in thioredoxin, and the large pKa downshift of the deeply buried catalytic Cys283 in HMCK. We anticipate that PME-CpHMD will offer proper pH control to improve the accuracies of MD simulations and enable mechanistic studies of proton-coupled dynamical processes that are ubiquitous in biology but remain poorly understood due to the lack of experimental tools and limitation of current MD simulations.
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Affiliation(s)
- Julie A Harris
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland21201, United States
| | - Ruibin Liu
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland21201, United States
| | - Vinicius Martins de Oliveira
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland21201, United States.,Lilly Biotechnology Center, San Diego, California92121, United States
| | | | - Jack A Henderson
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland21201, United States
| | - Jana Shen
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland21201, United States
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Henderson JA, Liu R, Harris JA, Huang Y, de Oliveira VM, Shen J. A Guide to the Continuous Constant pH Molecular Dynamics Methods in Amber and CHARMM [Article v1.0]. Living J Comput Mol Sci 2022; 4:1563. [PMID: 36776714 PMCID: PMC9910290 DOI: 10.33011/livecoms.4.1.1563] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Like temperature and pressure, solution pH is an important environmental variable in biomolecular simulations. Virtually all proteins depend on pH to maintain their structure and function. In conventional molecular dynamics (MD) simulations of proteins, pH is implicitly accounted for by assigning and fixing protonation states of titratable sidechains. This is a significant limitation, as the assigned protonation states may be wrong and they may change during dynamics. In this tutorial, we guide the reader in learning and using the various continuous constant pH MD methods in Amber and CHARMM packages, which have been applied to predict pK a values and elucidate proton-coupled conformational dynamics of a variety of proteins including enzymes and membrane transporters.
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Affiliation(s)
| | - Ruibin Liu
- University of Maryland School of Pharmacy, Baltimore, MD
| | | | - Yandong Huang
- University of Maryland School of Pharmacy, Baltimore, MD
| | | | - Jana Shen
- University of Maryland School of Pharmacy, Baltimore, MD
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Aghili Yajadda MM, Robinson PA, Henderson JA. Generalized neural field theory of cortical plasticity illustrated by an application to the linear phase of ocular dominance column formation in primary visual cortex. Biol Cybern 2022; 116:33-52. [PMID: 34773503 DOI: 10.1007/s00422-021-00901-w] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 09/30/2021] [Indexed: 06/13/2023]
Abstract
Physiologically based neural field theory (NFT) is extended to encompass cortical plasticity dynamics. An illustrative application is provided which treats the evolution of the connectivity of left- and right-eye visual stimuli to neuronal populations in the primary visual cortex (V1), and the initial, linear phase of formation of approximately one-dimensional (1D) ocular dominance columns (ODCs) that sets their transverse spatial scale. This links V1 activity, structure, and physiology within a single theory that already accounts for a range of other brain activity and connectivity phenomena, thereby enabling ODC formation and many other phenomena to be interrelated and cortical parameters to be constrained across multiple domains. The results accord with experimental ODC widths for realistic cortical parameters and are based directly on a unified description of the neuronal populations involved, their connection strengths, and the neuronal activity they support. Other key results include simple analytic approximations for ODC widths and the parameters of maximum growth rate, constraints on cortical excitatory and inhibitory gains, elucidation of the roles of specific poles of the V1 response function, and the fact that ODCs are not formed when input stimuli are fully correlated between eyes. This work provides a basis for further generalization of NFT to model other plasticity phenomena, thereby linking them to the range multiscale phenomena accounted for by NFT.
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Affiliation(s)
- M M Aghili Yajadda
- School of Physics, University of Sydney, Sydney, NSW, 2006, Australia
- Center for Integrative Brain Function, University of Sydney, Sydney, NSW, 2006, Australia
| | - P A Robinson
- School of Physics, University of Sydney, Sydney, NSW, 2006, Australia
- Center for Integrative Brain Function, University of Sydney, Sydney, NSW, 2006, Australia
| | - J A Henderson
- School of Physics, University of Sydney, Sydney, NSW, 2006, Australia.
- Center for Integrative Brain Function, University of Sydney, Sydney, NSW, 2006, Australia.
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Liu R, Verma N, Henderson JA, Zhan S, Shen J. Profiling MAP kinase cysteines for targeted covalent inhibitor design. RSC Med Chem 2022; 13:54-63. [PMID: 35224496 PMCID: PMC8792824 DOI: 10.1039/d1md00277e] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 10/28/2021] [Indexed: 07/20/2023] Open
Abstract
Mitogen-activated protein kinases (MAPK) are important therapeutic targets, and yet no inhibitors have advanced to the market. Here we applied the GPU-accelerated continuous constant pH molecular dynamics (CpHMD) to calculate the pK a's and profile the cysteine reactivities of all 14 MAPKs for assisting the targeted covalent inhibitor design. The simulations not only recapitulated but also rationalized the reactive cysteines in the front pocket of JNK1/2/3 and the extended front pocket of p38α. Interestingly, the DFG - 1 cysteine in the DFG-in conformation of ERK1/ERK2 was found somewhat reactive or unreactive; however, simulations of MKK7 showed that switching to the DFG-out conformation makes the DFG - 1 cysteine reactive, suggesting the advantage of type II covalent inhibitors. Additionally, the simulations prospectively predicted several druggable cysteine and lysine sites, including the αH head cysteine in JNK1/3 and DFG + 6 cysteine in JNK2, corroborating the chemical proteomic screening data. Given the low cost and the ability to offer physics-based rationales, we envision CpHMD simulations to complement the chemo-proteomic platform for systematic profiling cysteine reactivities for targeted covalent drug discovery.
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Affiliation(s)
- Ruibin Liu
- University of Maryland School of Pharmacy Baltimore MD USA
| | - Neha Verma
- University of Maryland School of Pharmacy Baltimore MD USA
| | | | - Shaoqi Zhan
- University of Maryland School of Pharmacy Baltimore MD USA
| | - Jana Shen
- University of Maryland School of Pharmacy Baltimore MD USA
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Abstract
Malaria remains a global health threat─over 400,000 deaths occurred in 2019. Plasmepsins are promising targets of antimalarial therapeutics; however, no inhibitors have reached the clinic. To fuel the progress, a detailed understanding of the pH- and ligand-dependent conformational dynamics of plasmepsins is needed. Here we present the continuous constant pH molecular dynamics study of the prototypical plasmepsin II and its complexed form with a substrate analogue. The simulations revealed that the catalytic dyads D34 and D214 are highly coupled in the apo protein and that the pepstatin binding enhances the difference in proton affinity, making D34 the general base and D214 the general acid. The simulations showed that the flap adopts an open state regardless of pH; however, upon pepstatin binding the flap can close or open depending on the protonation state of D214. These and other data are discussed and compared with the off-targets human cathepsin D and renin. This study lays the groundwork for a systematic investigation of pH- and ligand-modulated dynamics of the entire family of plasmepsins to help design more potent and selective inhibitors.
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Affiliation(s)
- Jack A Henderson
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, United States
| | - Jana Shen
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, United States
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Abstract
Many membrane channels, transporters, and receptors utilize a pH gradient or proton coupling to drive functionally relevant conformational transitions. Conventional molecular dynamics simulations employ fixed protonation states, thus neglecting the coupling between protonation and conformational equilibria. Here we describe the membrane-enabled hybrid-solvent continuous constant pH molecular dynamics method for capturing atomic details of proton-coupled conformational dynamics of transmembrane proteins. Example protocols from our recent application studies of proton channels and ion/substrate transporters are discussed.
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Affiliation(s)
- Yandong Huang
- College of Computer Engineering, Jimei University, Xiamen, Fujian, China
| | | | - Jana Shen
- University of Maryland School of Pharmacy, Baltimore, MD, USA.
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Verma N, Henderson JA, Shen J. Proton-Coupled Conformational Activation of SARS Coronavirus Main Proteases and Opportunity for Designing Small-Molecule Broad-Spectrum Targeted Covalent Inhibitors. J Am Chem Soc 2020; 142:21883-21890. [PMID: 33320670 PMCID: PMC7754784 DOI: 10.1021/jacs.0c10770] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [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: 10/11/2020] [Indexed: 02/08/2023]
Abstract
The SARS coronavirus 2 (SARS-CoV-2) main protease (Mpro) is an attractive broad-spectrum antiviral drug target. Despite the enormous progress in structure elucidation, the Mpro's structure-function relationship remains poorly understood. Recently, a peptidomimetic inhibitor has entered clinical trial; however, small-molecule orally available antiviral drugs have yet to be developed. Intrigued by a long-standing controversy regarding the existence of an inactive state, we explored the proton-coupled dynamics of the Mpros of SARS-CoV-2 and the closely related SARS-CoV using a newly developed continuous constant pH molecular dynamics (MD) method and microsecond fixed-charge all-atom MD simulations. Our data supports a general base mechanism for Mpro's proteolytic function. The simulations revealed that protonation of His172 alters a conserved interaction network that upholds the oxyanion loop, leading to a partial collapse of the conserved S1 pocket, consistent with the first and controversial crystal structure of SARS-CoV Mpro determined at pH 6. Interestingly, a natural flavonoid binds SARS-CoV-2 Mpro in the close proximity to a conserved cysteine (Cys44), which is hyper-reactive according to the CpHMD titration. This finding offers an exciting new opportunity for small-molecule targeted covalent inhibitor design. Our work represents a first step toward the mechanistic understanding of the proton-coupled structure-dynamics-function relationship of CoV Mpros; the proposed strategy of designing small-molecule covalent inhibitors may help accelerate the development of orally available broad-spectrum antiviral drugs to stop the current pandemic and prevent future outbreaks.
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Affiliation(s)
- Neha Verma
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, United States
| | - Jack A Henderson
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, United States
| | - Jana Shen
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, United States
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Abstract
Renin is a pepsin-like aspartyl protease and an important drug target for the treatment of hypertension; despite three decades' research, its pH-dependent structure-function relationship remains poorly understood. Here, we employed continuous constant pH molecular dynamics (CpHMD) simulations to decipher the acid/base roles of renin's catalytic dyad and the conformational dynamics of the flap, which is a common structural feature among aspartyl proteases. The calculated pKa's suggest that catalytic Asp38 and Asp226 serve as the general base and acid, respectively, in agreement with experiment and supporting the hypothesis that renin's neutral optimum pH is due to the substrate-induced pKa shifts of the aspartic dyad. The CpHMD data confirmed our previous hypothesis that hydrogen bond formation is the major determinant of the dyad pKa order. Additionally, our simulations showed that renin's flap remains open regardless of pH, although a Tyr-inhibited state is occasionally formed above pH 5. These findings are discussed in comparison to the related aspartyl proteases, including β-secretases 1 and 2, cathepsin D, and plasmepsin II. Our work represents a first step toward a systematic understanding of the pH-dependent structure-dynamics-function relationships of pepsin-like aspartyl proteases that play important roles in biology and human disease states.
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Affiliation(s)
- Shuhua Ma
- Department of Chemistry, Jess and Mildred Fisher College of Science and Mathematics, Towson University, Towson, Maryland 21252, United States
| | - Jack A Henderson
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, United States
| | - Jana Shen
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, United States
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Alnaas AA, Watson-Siriboe A, Tran S, Negussie M, Henderson JA, Osterberg JR, Chon NL, Harrott BM, Oviedo J, Lyakhova T, Michel C, Reisdorph N, Reisdorph R, Shearn CT, Lin H, Knight JD. Multivalent lipid targeting by the calcium-independent C2A domain of synaptotagmin-like protein 4/granuphilin. J Biol Chem 2020; 296:100159. [PMID: 33277360 PMCID: PMC7857503 DOI: 10.1074/jbc.ra120.014618] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 11/03/2020] [Accepted: 12/04/2020] [Indexed: 12/15/2022] Open
Abstract
Synaptotagmin-like protein 4 (Slp-4), also known as granuphilin, is a Rab effector responsible for docking secretory vesicles to the plasma membrane before exocytosis. Slp-4 binds vesicular Rab proteins via an N-terminal Slp homology domain, interacts with plasma membrane SNARE complex proteins via a central linker region, and contains tandem C-terminal C2 domains (C2A and C2B) with affinity for phosphatidylinositol-(4,5)-bisphosphate (PIP2). The Slp-4 C2A domain binds with low nanomolar apparent affinity to PIP2 in lipid vesicles that also contain background anionic lipids such as phosphatidylserine but much weaker when either the background anionic lipids or PIP2 is removed. Through computational and experimental approaches, we show that this high-affinity membrane binding arises from concerted interaction at multiple sites on the C2A domain. In addition to a conserved PIP2-selective lysine cluster, a larger cationic surface surrounding the cluster contributes substantially to the affinity for physiologically relevant lipid compositions. Although the K398A mutation in the lysine cluster blocks PIP2 binding, this mutated protein domain retains the ability to bind physiological membranes in both a liposome-binding assay and MIN6 cells. Molecular dynamics simulations indicate several conformationally flexible loops that contribute to the nonspecific cationic surface. We also identify and characterize a covalently modified variant that arises through reactivity of the PIP2-binding lysine cluster with endogenous bacterial compounds and binds weakly to membranes. Overall, multivalent lipid binding by the Slp-4 C2A domain provides selective recognition and high-affinity docking of large dense core secretory vesicles to the plasma membrane.
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Affiliation(s)
- Aml A Alnaas
- Department of Chemistry, University of Colorado Denver, Denver, Colorado, USA
| | | | - Sherleen Tran
- Department of Chemistry, University of Colorado Denver, Denver, Colorado, USA
| | - Mikias Negussie
- Department of Chemistry, University of Colorado Denver, Denver, Colorado, USA
| | - Jack A Henderson
- Department of Chemistry, University of Colorado Denver, Denver, Colorado, USA
| | - J Ryan Osterberg
- Department of Chemistry, University of Colorado Denver, Denver, Colorado, USA
| | - Nara L Chon
- Department of Chemistry, University of Colorado Denver, Denver, Colorado, USA
| | - Beckston M Harrott
- Department of Chemistry, University of Colorado Denver, Denver, Colorado, USA
| | - Julianna Oviedo
- Department of Chemistry, University of Colorado Denver, Denver, Colorado, USA
| | - Tatyana Lyakhova
- Department of Chemistry, University of Colorado Denver, Denver, Colorado, USA
| | - Cole Michel
- Department of Pharmaceutical Sciences, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Nichole Reisdorph
- Department of Pharmaceutical Sciences, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Richard Reisdorph
- Department of Pharmaceutical Sciences, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Colin T Shearn
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology and Nutrition, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Hai Lin
- Department of Chemistry, University of Colorado Denver, Denver, Colorado, USA.
| | - Jefferson D Knight
- Department of Chemistry, University of Colorado Denver, Denver, Colorado, USA.
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Henderson JA, Verma N, Harris RC, Liu R, Shen J. Assessment of proton-coupled conformational dynamics of SARS and MERS coronavirus papain-like proteases: Implication for designing broad-spectrum antiviral inhibitors. J Chem Phys 2020; 153:115101. [PMID: 32962355 PMCID: PMC7499820 DOI: 10.1063/5.0020458] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [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] [Indexed: 12/17/2022] Open
Abstract
Broad-spectrum antiviral drugs are urgently needed to stop the Coronavirus Disease 2019 pandemic and prevent future ones. The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is related to the SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV), which have caused the previous outbreaks. The papain-like protease (PLpro) is an attractive drug target due to its essential roles in the viral life cycle. As a cysteine protease, PLpro is rich in cysteines and histidines, and their protonation/deprotonation modulates catalysis and conformational plasticity. Here, we report the pKa calculations and assessment of the proton-coupled conformational dynamics of SARS-CoV-2 in comparison to SARS-CoV and MERS-CoV PLpros using the recently developed graphical processing unit (GPU)-accelerated implicit-solvent continuous constant pH molecular dynamics method with a new asynchronous replica-exchange scheme, which allows computation on a single GPU card. The calculated pKa's support the catalytic roles of the Cys-His-Asp triad. We also found that several residues can switch protonation states at physiological pH among which is C270/271 located on the flexible blocking loop 2 (BL2) of SARS-CoV-2/CoV PLpro. Simulations revealed that the BL2 can open and close depending on the protonation state of C271/270, consistent with the most recent crystal structure evidence. Interestingly, despite the lack of an analogous cysteine, BL2 in MERS-CoV PLpro is also very flexible, challenging a current hypothesis. These findings are supported by the all-atom fixed-charge simulations and provide a starting point for more detailed studies to assist the structure-based design of broad-spectrum inhibitors against CoV PLpros.
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Affiliation(s)
- Jack A Henderson
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, USA
| | - Neha Verma
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, USA
| | - Robert C Harris
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, USA
| | - Ruibin Liu
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, USA
| | - Jana Shen
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, Maryland 21201, USA
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Henderson JA, Verma N, Shen J. Assessment of Proton-Coupled Conformational Dynamics of SARS and MERS Coronavirus Papain-like Proteases: Implication for Designing Broad-Spectrum Antiviral Inhibitors. bioRxiv 2020:2020.06.30.181305. [PMID: 32637952 PMCID: PMC7337382 DOI: 10.1101/2020.06.30.181305] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Broad-spectrum antiviral drugs are urgently needed to stop the COVID-19 pandemic and prevent future ones. The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is related to SARS-CoV and Middle East respiratory syndrome coronavirus (MERS-CoV), which have caused the previous outbreaks. The papain-like protease (PLpro) is an attractive drug target due to its essential roles in the viral life cycle. As a cysteine protease, PLpro is rich in cysteines and histidines and their protonation/deprotonation modulates catalysis and conformational plasticity. Here we report the pKa calculations and assessment of the proton-coupled conformational dynamics of SARS-CoV-2 in comparison to SARS-CoV and MERS-CoV PLpros using a newly developed GPU-accelerated implicit-solvent continuous constant pH molecular dynamics method with an asynchronous replica-exchange scheme. The calculated pKa's support the catalytic roles of the Cys-His-Asp triad. We also found that several residues can switch protonation states at physiological pH, among which is C270/271 located on the flexible blocking loop 2 (BL2) of SARS-CoV-2/CoV PLpro. Simulations revealed that the BL2 conformational dynamics is coupled to the titration of C271/270, in agreement with the crystal structures of SARS-CoV-2 PLpro. Simulations also revealed that BL2 in MERS-CoV PLpro is very flexible, sampling both open and closed states despite the lack of an analogous cysteine. Our work provides a starting point for more detailed mechanistic studies to assist structure-based design of broad-spectrum inhibitors against CoV PLpros.
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Affiliation(s)
- Jack A. Henderson
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201
| | - Neha Verma
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201
| | - Jana Shen
- Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201
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Henderson JA, Shen J. Activation of the Voltage Gated Proton Channel Hv1: A Constant pH Molecular Dynamics Study. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Abstract
The role of water in protein-ligand binding has been an intensely studied topic in recent years; however, how ligand protonation state change perturbs water has not been considered. Here we show that water dynamics and interactions can be controlled by the protonation state of ligand using continuous constant pH molecular dynamics simulations of two closely related model systems, β-secretase 1 and 2 (BACE1 and BACE2), in complex with a small-molecule inhibitor. Simulations revealed that, upon binding, the inhibitor pyrimidine ring remains deprotonated in BACE1 but becomes protonated in BACE2. Pyrimidine protonation results in water displacement, rigidification of the binding pocket, and shift in the ligand binding mode from water-mediated to direct hydrogen bonding. These findings not only support but also rationalize the most recent structure-selectivity data in BACE1 drug design. Binding-induced protonation state changes are likely common; our work offers a glimpse at how modeling protein-ligand binding while allowing ligand titration can further advance the understanding of water and structure-based drug design.
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Affiliation(s)
- Jack A Henderson
- Department of Pharmaceutical Sciences , University of Maryland School of Pharmacy , Baltimore , Maryland 21201 , United States
| | - Robert C Harris
- Department of Pharmaceutical Sciences , University of Maryland School of Pharmacy , Baltimore , Maryland 21201 , United States
| | - Cheng-Chieh Tsai
- Department of Pharmaceutical Sciences , University of Maryland School of Pharmacy , Baltimore , Maryland 21201 , United States
| | - Jana Shen
- Department of Pharmaceutical Sciences , University of Maryland School of Pharmacy , Baltimore , Maryland 21201 , United States
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14
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Huang Y, Yue Z, Tsai CC, Henderson JA, Shen J. Predicting Catalytic Proton Donors and Nucleophiles in Enzymes: How Adding Dynamics Helps Elucidate the Structure-Function Relationships. J Phys Chem Lett 2018; 9:1179-1184. [PMID: 29461836 PMCID: PMC6555141 DOI: 10.1021/acs.jpclett.8b00238] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [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: 05/23/2023]
Abstract
Despite the relevance of understanding structure-function relationships, robust prediction of proton donors and nucleophiles in enzyme active sites remains challenging. Here we tested three types of state-of-the-art computational methods to calculate the p Ka's of the buried and hydrogen bonded catalytic dyads in five enzymes. We asked the question what determines the p Ka order, i.e., what makes a residue proton donor vs a nucleophile. The continuous constant pH molecular dynamics simulations captured the experimental p Ka orders and revealed that the negative nucleophile is stabilized by increased hydrogen bonding and solvent exposure as compared to the proton donor. Surprisingly, this simple trend is not apparent from crystal structures and the static structure-based calculations. While the generality of the findings awaits further testing via a larger set of data, they underscore the role of dynamics in bridging enzyme structures and functions.
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Affiliation(s)
- Yandong Huang
- Department of Pharmaceutical Sciences , University of Maryland School of Pharmacy , Baltimore , Maryland 21201 , United States
| | - Zhi Yue
- Department of Pharmaceutical Sciences , University of Maryland School of Pharmacy , Baltimore , Maryland 21201 , United States
| | - Cheng-Chieh Tsai
- Department of Pharmaceutical Sciences , University of Maryland School of Pharmacy , Baltimore , Maryland 21201 , United States
| | - Jack A Henderson
- Department of Pharmaceutical Sciences , University of Maryland School of Pharmacy , Baltimore , Maryland 21201 , United States
| | - Jana Shen
- Department of Pharmaceutical Sciences , University of Maryland School of Pharmacy , Baltimore , Maryland 21201 , United States
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15
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Monaghan M, Travers B, Kinsella M, Gallagher J, O'Connell E, Watson C, O'Hanlon R, Ledwidge M, Mailey J, Henderson JA, Dixon L, McDonald K. 30 Lack of specialist involvement in heart failure diagnosis leave concerning gaps in management: an all ireland analysis: Abstract 30 Table 1. Heart 2015. [DOI: 10.1136/heartjnl-2015-308621.30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Robinson PA, Sarkar S, Pandejee GM, Henderson JA. Determination of effective brain connectivity from functional connectivity with application to resting state connectivities. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 90:012707. [PMID: 25122335 DOI: 10.1103/physreve.90.012707] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Indexed: 06/03/2023]
Abstract
Neural field theory insights are used to derive effective brain connectivity matrices from the functional connectivity matrix defined by activity covariances. The symmetric case is exactly solved for a resting state system driven by white noise, in which strengths of connections, often termed effective connectivities, are inferred from functional data; these include strengths of connections that are underestimated or not detected by anatomical imaging. Proximity to criticality is calculated and found to be consistent with estimates obtainable from other methods. Links between anatomical, effective, and functional connectivity and resting state activity are quantified, with applicability to other complex networks. Proof-of-principle results are illustrated using published experimental data on anatomical connectivity and resting state functional connectivity. In particular, it is shown that functional connection matrices can be used to uncover the existence and strength of connections that are missed from anatomical connection matrices, including interhemispheric connections that are difficult to track with techniques such as diffusion spectrum imaging.
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Affiliation(s)
- P A Robinson
- School of Physics, University of Sydney, New South Wales 2006, Australia Center for Integrative Brain Function, University of Sydney, New South Wales 2006, Australia Cooperative Research Center for Alertness, Safety, and Productivity, University of Sydney, New South Wales 2006, Australia Neurosleep, 431 Glebe Point Rd, Glebe, New South Wales 2037, Australia Center for Integrative Research and Understanding of Sleep, 431 Glebe Pt Rd, Glebe, New South Wales 2037, Australia and Brain Dynamics Center, Westmead Millennium Institute, Darcy Rd, Westmead, New South Wales 2145, Australia
| | - S Sarkar
- School of Physics, University of Sydney, New South Wales 2006, Australia and Design Lab, Faculty of Architecture, Design, and Planning, University of Sydney, New South Wales 2006, Australia
| | | | - J A Henderson
- School of Physics, University of Sydney, New South Wales 2006, Australia
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Abstract
It is shown that homogeneous, short-range, two-dimensional (2D) cortical connectivity, without modularity, hierarchy, or other specialized structure, reproduces key observed properties of cortical networks, including low path length, high clustering and modularity index, and apparent hierarchical block-diagonal structure in connection matrices. Geometry strongly influences connection matrices, implying that simple interpretations of connectivity measures as reflecting specialized structure can be misleading: Such apparent structure is seen in strictly uniform, locally connected architectures in 2D. Geometry is thus a proxy for function, modularity, and hierarchy and must be accounted for when structural inferences are made.
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Affiliation(s)
- J A Henderson
- School of Physics, University of Sydney, New South Wales, Australia
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18
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Robinson PA, Henderson JA, Matar E, Riley P, Gray RT. Dynamical reconnection and stability constraints on cortical network architecture. Phys Rev Lett 2009; 103:108104. [PMID: 19792345 DOI: 10.1103/physrevlett.103.108104] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2009] [Indexed: 05/26/2023]
Abstract
Stability under dynamical changes to network connectivity is invoked alongside previous criteria to constrain brain network architecture. A new hierarchical network is introduced that satisfies all these constraints, unlike more commonly studied regular, random, and small-world networks. It is shown that hierarchical networks can simultaneously have high clustering, short path lengths, and low wiring costs, while being robustly stable under large scale reconnection of substructures.
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Affiliation(s)
- P A Robinson
- School of Physics, University of Sydney, Sydney, New South Wales 2006, Australia
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19
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Lima FB, Henderson JA, Reddy AP, Tokuyama Y, Hubert GW, Kuhar MJ, Bethea CL. Unique responses of midbrain CART neurons in macaques to ovarian steroids. Brain Res 2008; 1227:76-88. [PMID: 18598674 DOI: 10.1016/j.brainres.2008.05.078] [Citation(s) in RCA: 13] [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] [Received: 04/11/2008] [Revised: 05/14/2008] [Accepted: 05/20/2008] [Indexed: 10/22/2022]
Abstract
CART (cocaine and amphetamine regulated transcript) is a neuropeptide involved in the control of several physiological processes, such as response to psychostimulants, food intake, depressive diseases and neuroprotection. It is robustly expressed in the brain, mainly in regions that control emotional and stress responses and it is regulated by estrogen in the hypothalamus. There is a distinct population of CART neurons located in the vicinity of the Edinger-Westphal nucleus of the midbrain that also colocalize urocortin-1. The aims of this study were 1) to determine the distribution of CART immunoreactive neurons in the monkey midbrain, 2) to examine the effects of estrogen (E) and progesterone (P) on midbrain CART mRNA and peptide expression and 3) to determine whether midbrain CART neurons contain steroid receptors. Adult female rhesus monkeys (Macaca mulatta) were spayed and either treated with placebo (OVX), estrogen alone (E), progesterone alone (P) or E+P. Animals were prepared (a) for RNA extraction followed by microarray analysis and quantitative (q) RT-PCR (n=3/group); (b) for immunohistochemical analysis of CART and CART+tryptophan hydroxylase (TPH), CART+estrogen receptors (ER) or CART+progesterone receptors (n=5/group) and (c) for Western blots (n=3/group). Both E- and E+P-administration decreased CART gene expression on the microarray and with qRT-PCR. Stereological analysis of CART immunostaining at five levels of the Edinger-Westphal nucleus indicated little effect of E or E+P administration on the area of CART immunostaining. However, P administration increased CART-immunopositive area in comparison to the OVX control group with Student's t-test, but not with ANOVA. CART 55-102 detection on Western blot was unchanged by hormone administration. ERbeta and PR were detected in CART neurons and CART fibers appeared to innervate TPH-positive serotonin neurons in the dorsal raphe. In summary, E decreased CART mRNA, but this effect did not translate to the protein level. Moreover, P administration alone had a variable effect on CART mRNA, but it caused an increase in CART immunostaining. Together, the data suggest that CART neurons in the midbrain have a unique steroid response, which may be mediated by nuclear receptors, neuroactive steroids or interneurons.
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Affiliation(s)
- F B Lima
- Division of Reproductive Sciences, Oregon National Primate Research Center, Beaverton, Oregon 97006, USA
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20
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Henderson JA, Bethea CL. Differential effects of ovarian steroids and raloxifene on serotonin 1A and 2C receptor protein expression in macaques. Endocrine 2008; 33:285-93. [PMID: 19021000 PMCID: PMC3267476 DOI: 10.1007/s12020-008-9087-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Accepted: 07/28/2008] [Indexed: 12/20/2022]
Abstract
To further understand the role of ovarian hormones in the function of the serotonin neural system, we investigated the effects of estradiol (E), progesterone (P), and raloxifene on 5HT 1A and 2C receptor protein expression in the dorsal raphe region using Western blot analysis. Adult rhesus macaques (Macaca mulatta) were ovariectomized (Ovx) and implanted with Silastic capsules containing E or P. In the first paradigm, animals that had been Ovx for 6-16 months were treated for 1 month with E (El) or E + P (EP1) and compared to animals that were untreated and Ovx for 5 months (n = 4 per group). In the second paradigm, comparisons were made between animals that were Ovx and untreated for 5 months, or Ovx and immediately implanted with Silastic capsules containing E or E + P for 5 months (E5, EP5), or administered raloxifene in the diet for 5 months (Ral5) (n = 4 per group). The dorsal raphe region was harvested, homogenized and a crude membrane fraction was obtained for examination of receptor proteins. In the first paradigm, 5HT1A receptor protein expression was significantly lower in E1 and EPI treatment groups compared to the Ovx-control group (ANOVA P = 0.01; posthoc P < 0.03), but 5HT2C receptor expression was unaffected by 1 month of E or EP treatment. In the second paradigm, there was no difference in 5HT1A receptor expression between the Ovx-control group and the E5 group, but 5HT1A receptor expression was significantly suppressed in the EP5 group (ANOVA P = 0.04; posthoc P < 0.05). In addition, 5HT2C expression increased in the E5 treatment group relative to the Ovx-control group. Addition of P to the E5 regimen prevented the E5-induced increase in 5HT2C receptor expression and significantly reduced 5HT2C receptor expression to a level below that observed in the Ovx-control group (ANOVA P = 0.001; posthoc P < 0.05). Thus, 5HT1A receptor may lose sensitivity to the suppressive effect of E after 5 months, whereas the 5HT2C receptor increases. However, addition of P in the EP5 regimen maintains the regulatory effects observed with 1 month of treatment. 5HT1A receptor protein levels were higher with raloxifene treatment than in Ovx-control animals (P < 0.01), suggesting that raloxifene may antagonize residual E in Ovx animals.
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Affiliation(s)
- J A Henderson
- Division of Reproductive Sciences, Oregon National Primate Research Center, Beaverton, OR 97006, USA
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Slattery ML, Schumacher MC, Lanier AP, Edwards S, Edwards R, Murtaugh MA, Sandidge J, Day GE, Kaufman D, Kanekar S, Tom-Orme L, Henderson JA. A prospective cohort of American Indian and Alaska Native people: study design, methods, and implementation. Am J Epidemiol 2007; 166:606-15. [PMID: 17586578 PMCID: PMC2556228 DOI: 10.1093/aje/kwm109] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [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: 11/12/2022] Open
Abstract
In 2001, the National Cancer Institute funded three centers to test the feasibility of establishing a cohort of American Indian and Alaska Native people. Participating tribal organizations named the study EARTH (Education and Research Towards Health). This paper describes the study methods. A computerized data collection and tracking system was developed using audio computer-assisted survey methodology with touch screens. Data were collected on diet, physical activity, lifestyle and cultural practices, medical and reproductive history, and family history of heart disease, diabetes, and cancer. In addition, a small panel of medical measurements was obtained, including height, weight, waist and hip circumferences, blood pressure, and a lipid panel plus glucose. At the completion of the enrollment visit, data were used to provide immediate health feedback to study participants. During the initial funding period, the authors anticipate enrolling 16,000 American Indian and Alaska Native participants. The age distribution of the study population was similar to that reported in the 2000 US Census for the relevant populations. A component critical to the success of the EARTH Study has been the partnerships with tribal members. The study has focused on involvement of American Indian and Alaska Native communities in development and implementation and on provision of feedback to participants and communities.
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Affiliation(s)
- M L Slattery
- Department of Internal Medicine, The University of Utah, Salt Lake City, UT 84108, USA.
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Henderson JA, Phillips AJK, Robinson PA. Multielectrode electroencephalogram power spectra: theory and application to approximate correction of volume conduction effects. Phys Rev E Stat Nonlin Soft Matter Phys 2006; 73:051918. [PMID: 16802978 DOI: 10.1103/physreve.73.051918] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2005] [Indexed: 05/10/2023]
Abstract
Using a physiologically based model of brain activity, electroencephalogram (EEG) power spectra are calculated for signals derived from general linear combinations of voltages from multiple electrodes, with and without filtering by volume conduction. Two simple methods of combining scalp measurements to estimate unfiltered EEG power spectra are then proposed and their accuracy and robustness are explored, using the model predictions as an illustration. It is found that these methods, including a case that uses just three electrodes, enable improved estimation of the underlying spectrum relative to each of several widely used combinations alone.
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Affiliation(s)
- J A Henderson
- School of Physics, University of Sydney, New South Wales 2006, Australia
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23
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Abstract
Oral contraceptives (OCs) are the most widely prescribed and effective of the reversible contraceptive methods. In addition to inhibiting ovulation, OCs alter central nervous system function in women; however, methodological problems have prevented clear human studies. Thus, in this experiment we investigated the effects of OC treatment on behavior, hypothalamic- pituitary-adrenal axis function and the central nervous system in 75 adult female cynomolgus monkeys (Macaca fascicularis) housed in social groups of four to five monkeys per pen. Monkey social groups were randomly divided into either a control or an OC treatment group which was administered a clinically prescribed OC (Triphasil(R), levonorgestrel and ethinyl estradiol tablets) for 2 years. OC treatment increased the frequency of contact aggression received, time spent in locomotion, and sitting close to another animal, and decreased time spent fearfully scanning. OC treatment decreased heart rate, increased activity levels, and increased baseline cortisol concentrations and the cortisol response to adrenocorticotropin compared to control animals. OC treatment decreased the prolactin response to fenfluramine suggesting decreased serotonergic activity. These results suggest that this triphasic OC disrupts social behavior, hypothalamic-pituitary-adrenal axis regulation and the underlying central nervous system function.
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Affiliation(s)
- J A Henderson
- Department of Pathology (Comparative Medicine), Program in Neuroscience, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1010, USA.
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24
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Abstract
Stress and sex steroidal milieu can each influence mood in women. The purpose of this study was to compare the effect of long-term conjugated equine estrogen (CEE), soy phytoestrogen (SPE), and social subordination stress on dorsal raphe serotonin neurotransmission of ovariectomized cynomolgus monkeys. Tryptophan hydroxylase (TPH) and serotonin reuptake transporter (SERT) protein content were determined, and the in vitro degradation of macaque SERT protein was examined in the presence and absence of protease inhibitors, serotonin (5-HT), and citalopram. Like CEE, SPE increased TPH protein levels. Social subordinates had markedly lower TPH protein levels than dominants regardless of hormone replacement. Therefore, these two variables had independent and additive effects. CEE and SPE increased SERT, and social status had no effect. Thus, the hormone-induced increase in SERT was accompanied by increased 5-HT synthesis and neuronal firing, which appears biologically reasonable as 5-HT prevented SERT degradation in vitro.
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Affiliation(s)
- C A Shively
- Department of Pathology, Section of Comparative Medicine, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
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25
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Henderson JA. Agreements changing the forum for resolving malpractice claims. LAW AND CONTEMPORARY PROBLEMS 2001; 49:243-51. [PMID: 10278661] [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: 02/12/2023]
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Hu D, Hannah J, Gray RS, Jablonski KA, Henderson JA, Robbins DC, Lee ET, Welty TK, Howard BV. Effects of obesity and body fat distribution on lipids and lipoproteins in nondiabetic American Indians: The Strong Heart Study. Obes Res 2000; 8:411-21. [PMID: 11011907 DOI: 10.1038/oby.2000.51] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVES To examine the relationship between obesity and lipoprotein profiles and compare the effects of total obesity and central adiposity on lipids/lipoproteins in American Indians. RESEARCH METHODS AND PROCEDURES Participants were 773 nondiabetic American Indian women and 739 men aged 45 to 74 years participating in the Strong Heart Study. Total obesity was estimated using body mass index (BMI). Central obesity was measured as waist circumference. Lipoprotein measures included triglycerides, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, apolipoprotein AI (apoAI), and apolipoprotein B (apoB). Partial and canonical correlation analyses were used to examine the associations between obesity and lipids/ lipoproteins. RESULTS Women were more obese than men in Arizona (median BMI 32.1 vs. 29.2 kg/m2) and South Dakota and North Dakota (28.3 vs. 28.0 kg/m2), but there was no sex difference in waist circumference. Men had higher apoB and lower apoAI levels than did women. In women, when adjusted for center, gender, and age, BMI was significantly related to HDL cholesterol (r = -0.24, p < 0.001). There was a significant but weak relation with apoAI (r = -0.14, p < 0.001). Waist circumference was positively related to triglycerides (r = 0.14, p < 0.001) and negatively related to HDL cholesterol (r = -0.23, p < 0.001) and apoAI (r = -0.13, p < 0.001). In men, BMI was positively correlated with triglycerides (r = 0.30, p < 0.001) and negatively correlated with HDL cholesterol (r = -0.35, p < 0.001) and apoAI (r = -0.23, p < 0.001). Triglycerides increased with waist circumference (r = 0.30, p < 0.001) and HDL cholesterol decreased with waist circumference (r = -0.36, p < 0.001). In both women and men there was an inverted U-shaped relationship between obesity and waist with LDL cholesterol and apoB. In canonical correlation analysis, waist circumference received a greater weight (0.86) than did BMI (0.17) in women. However, the canonical weights were similar for waist (0.46) and BMI (0.56) in men. Only HDL cholesterol (-1.02) carried greater weight in women, whereas in men, triglycerides (0.50), and HDL cholesterol (-0.64) carried a large amount of weight. All the correlation coefficients between BMI, waist circumference, and the first canonical variable of lipids/lipoproteins or between the individual lipid/lipoprotein variables and the first canonical variable of obesity were smaller in women than in men. Triglycerides and HDL cholesterol showed clinically meaningful changes with BMI and waist circumference in men. All lipid/lipoprotein changes in women in relation to BMI and waist circumference were minimal. DISCUSSION The main lipoprotein abnormality related to obesity in American Indians was decreased HDL cholesterol, especially in men. Central adiposity was more associated with abnormal lipid/lipoprotein profiles than general obesity in women; both were equally important in men.
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Affiliation(s)
- D Hu
- MedStar Research Institute, Washington, DC 20010, USA
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27
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Jacobson GP, Henderson JA, McCaslin DL. A re-evaluation of tinnitus reliability testing. J Am Acad Audiol 2000; 11:156-61. [PMID: 10755811] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
The purposes of these investigations were to (1) evaluate tinnitus loudness measures of unskilled normal listeners asked to imagine that they are experiencing a constant monaural tonal tinnitus and (2) compare the performance of these listeners to that of a sample of patients with tinnitus. Subgroups of 24 patients participated in two investigations. Results suggest that (1) normal subjects asked to imagine a high-pitched, tonal tinnitus show significantly greater tinnitus loudness matching levels (a) when they do not have an external reference, (b) after a 1-week interval, and (c) for low-frequency matching tones; (2) patients with high-pitched tinnitus did not demonstrate statistically significant differences in tinnitus loudness judgments within or between sessions or frequencies; (3) tinnitus patients do not differ significantly from normals feigning tinnitus in the variability of tinnitus loudness matching levels within a single session (two measures) or after a 1-week interval (one measure); and (4) normals feigning tinnitus tended to choose significantly greater loudness matching levels than did tinnitus subjects.
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Affiliation(s)
- G P Jacobson
- Division of Audiology, Henry Ford Hospital, Detroit, Michigan 48202, USA
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Hu D, Henderson JA, Welty TK, Lee ET, Jablonski KA, Magee MF, Robbins DC, Howard BV. Glycemic control in diabetic American Indians. Longitudinal data from the Strong Heart Study. Diabetes Care 1999; 22:1802-7. [PMID: 10546011 DOI: 10.2337/diacare.22.11.1802] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To describe glycemic control and identify correlates of elevated HbA1c levels in diabetic American Indians participating in the Strong Heart Study, which is a longitudinal study of cardiovascular disease in American Indians in Arizona, Oklahoma, South Dakota, and North Dakota. RESEARCH DESIGN AND METHODS This analysis is based on data from the baseline (1989-1992) and first follow-up (1994-1995) examinations of the Strong Heart Study. The 1,581 diabetic participants included in this analysis were aged 45-74 years at baseline, were diagnosed with diabetes before and at baseline, and had their HbA1c levels measured at follow-up. HbA1c was used as the index of glycemic control. Characteristics that may affect glycemic control were evaluated for cross-sectional and longitudinal relationships by analysis of covariance and multiple regression. RESULTS There was no significant difference between median HbA1c at baseline (8.4%) and at follow-up (8.5%). Sex, age (inversely), and insulin and oral hypoglycemic agent therapy were significantly related to HbA1c levels in both the cross-sectional and longitudinal analyses. Current smoking, prior use of alcohol, and duration of diabetes were significant only for the cross-sectional data. Baseline HbA1c significantly and positively predicted HbA1c levels at follow-up. Comparison of HbA1c by therapy type shows that insulin therapy produced a significant decrease in HbA1c between the baseline and follow-up examinations. CONCLUSIONS Glycemic control was poor among diabetic American Indians participating in the Strong Heart Study. Women, patients taking insulin or oral hypoglycemic agents, and younger individuals had the worst control of all the participants. Baseline HbA1c, and weight loss predicted worsening of control, whereas insulin therapy predicted improvement in control. Additional therapies and/or approaches are needed to improve glycemic control in this population.
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Affiliation(s)
- D Hu
- MedStar Research Institute, Washington, DC 20010, USA.
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29
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Bartkowiak M, Henderson JA, Oitmaa J. High-temperature series expansion for the extended Hubbard model. Phys Rev B Condens Matter 1995; 51:14077-14084. [PMID: 9978333 DOI: 10.1103/physrevb.51.14077] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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30
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Henderson JA, Siliciano JA. Universal health care and the continued reliance on custom in determining medical malpractice. Cornell Law Rev 1994; 79:1382-1404. [PMID: 10141438] [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: 05/23/2023]
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31
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Oitmaa J, Yang J, Henderson JA, Zheng W. Large-U expansions for the Hubbard model at T=0. II. Phys Rev B Condens Matter 1993; 48:6210-6216. [PMID: 10009164 DOI: 10.1103/physrevb.48.6210] [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: 11/07/2022]
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32
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Henderson JA. Implications of outpatient surgery growth. OR Manager 1993; 9:24, 26. [PMID: 10171534] [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]
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33
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Henderson JA. Multi-unit providers surgery centers survey 1992. Surgicenters cut further into market. Mod Healthc 1992; 22:108-10. [PMID: 10170978] [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: 02/11/2023]
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34
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Henderson JA. Surgery centers continue pattern of growth. Mod Healthc 1991; 21:36-7. [PMID: 10170726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The number of outpatient surgery centers grew at an 11% clip in 1990, fueled by the continued shift of patients and procedures to the outpatient setting, according to a recent survey by SMG Marketing Group, a Chicago-based healthcare consulting and market research firm. But while figures project continued growth, competition and government regulation could limit future expansion.
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36
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Thomas SM, Fick AC, Henderson JA. Assessment of attitudes toward school-based health promotion programs. J La State Med Soc 1991; 143:37-40. [PMID: 2051124] [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] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Teachers from Orleans Parish public junior and senior high schools completed a survey designed to assess their health-related behaviors and their attitudes toward school-based health promotion programs. Findings suggest that teachers' behaviors and attitudes, as well as school policies toward smoking, are not optimal to creating a pro-health promotion environment. While teachers recognize the value of preventive programs for adolescents and many feel well qualified to implement such programs, few actually do. Resolution of these discrepancies are necessary early steps in increasing primary efforts needed for cancer control in Louisiana.
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Affiliation(s)
- S M Thomas
- Dept of Psychology, University of New Orleans
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37
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Henderson JA. Emerging contract incentives can add to hospitals' savings. Mod Healthc 1990; 20:38. [PMID: 10107221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Group purchasing organizations are trying to draw more volume out of their hospital members by offering additional price breaks if purchases meet performance targets, says John Henderson. The purchasing groups see the approach as a way to keep their promise to manufacturers of volume in return for discounts.
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38
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Henderson JA. Survey. Surgery centers continue making inroads. Mod Healthc 1990; 20:98-100. [PMID: 10104886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The number of surgery centers grew more than 25% in 1989, and these outposts now perform one of every six outpatient procedures. Ten years ago, hospital-based surgery suites handled 98% of the market.
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39
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Henderson JA. Nursing home market maturing. Health Ind Today 1989; 52:25-8. [PMID: 10295554] [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: 02/12/2023]
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40
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Henderson JA. Growth in surgery centers continues with integration. Health Ind Today 1989; 52:23-5. [PMID: 10318317] [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: 02/12/2023]
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41
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Henderson JA. Multi-unit providers survey. Surgery centers' success challenges hospitals. Mod Healthc 1989; 19:78-80. [PMID: 10293454] [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: 02/12/2023]
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42
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Henderson JA, Dunmire SN. Indications of rejuvenation in the HMO industry. Health Ind Today 1989; 52:21-3. [PMID: 10294695] [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: 04/13/2023]
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43
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Henderson JA. Hospital closings prompt more specialization. Health Ind Today 1989; 52:24-5, 31, 44. [PMID: 10293313] [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: 02/12/2023]
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Abstract
Spontaneous perforation of the esophagus (Boerhaave syndrome) is an emergency that requires early diagnosis if death or serious prolonged illness is to be averted. The cases of three patients with spontaneous esophageal perforation simulating other primary diagnoses are described. The respective referral diagnoses were pericarditis, lung abscess, and pancreatitis. Each case was characterized by severe illness, and by delay in diagnosis despite multiple consultations. Two patients died. The literature is reviewed and the causes of delay in diagnosis are analyzed. More than 40 years after the first report of successful surgical repair, spontaneous esophageal perforation is insufficiently considered in diagnostic hypotheses, yet may be confirmed or excluded by simple methods. All clinicians need to be alert to this lethal disease, and to be aware of its frequent atypical presentations.
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Affiliation(s)
- J A Henderson
- Department of Medicine, Ottawa General Hospital, Ontario, Canada
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45
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Henderson JA. Where group purchasing is headed. Health Ind Today 1989; 52:23-4, 46. [PMID: 10292829] [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: 02/12/2023]
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46
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Henderson JA. Hospitals should reassess group purchasing. Mod Healthc 1989; 19:80. [PMID: 10292049] [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: 04/13/2023]
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47
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Henderson JA, Dunmire SN. Changes play havoc with marketing plans. Health Ind Today 1989; 52:24-7. [PMID: 10318241] [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: 02/12/2023]
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48
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Henderson JA, Rowsell HC. Fatal Pasteurella multocida pneumonia in an IgA-deficient cat fancier. West J Med 1989; 150:208-10. [PMID: 2728443 PMCID: PMC1026352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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49
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Henderson JA. The prospect before us. Can Vet J 1989; 30:186-8. [PMID: 17423250 PMCID: PMC1681046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
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50
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Henderson JA. Physician office-based surgery: significant growth opportunity. Health Ind Today 1989; 52:18-9, 22, 30. [PMID: 10318240] [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: 02/12/2023]
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