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Miller EJ, Phan MD, Shah J, Honerkamp-Smith AR. Passive and reversible area regulation of supported lipid bilayers in response to fluid flow. Biophys J 2023; 122:2242-2255. [PMID: 36639867 PMCID: PMC10257118 DOI: 10.1016/j.bpj.2023.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 12/21/2022] [Accepted: 01/09/2023] [Indexed: 01/14/2023] Open
Abstract
Biological and model membranes are frequently subjected to fluid shear stress. However, membrane mechanical responses to flow remain incompletely described. This is particularly true of membranes supported on a solid substrate, and the influences of membrane composition and substrate roughness on membrane flow responses remain poorly understood. Here, we combine microfluidics, fluorescence microscopy, and neutron reflectivity to explore how supported lipid bilayer patches respond to controlled shear stress. We demonstrate that lipid membranes undergo a significant, passive, and partially reversible increase in membrane area due to flow. We show that these fluctuations in membrane area can be constrained, but not prevented, by increasing substrate roughness. Similar flow-induced changes to membrane structure may contribute to the ability of living cells to sense and respond to flow.
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Affiliation(s)
| | - Minh D Phan
- Large-Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Center for Neutron Science, Department of Chemical & Biomolecular Engineering, University of Delaware, Newark, Delaware
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2
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Phan MD, Shih KC, Kelley EG, Butler PD, Wagner NJ, Nagao M. Collective dynamics in the lipid phases of DMPC/cholesterol bilayers: A neutron spin-echo study. Biophys J 2023; 122:364a. [PMID: 36783848 DOI: 10.1016/j.bpj.2022.11.2009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Minh D Phan
- Center for Neutron Science, University of Delaware, Newark, DE, USA
| | - Kuo-Chih Shih
- Center for Neutron Science, University of Delaware, Newark, DE, USA
| | - Elizabeth G Kelley
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Paul D Butler
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | - Norman J Wagner
- Center for Neutron Science, University of Delaware, Newark, DE, USA
| | - Michihiro Nagao
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA
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3
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Ankner JF, Ashkar R, Browning JF, Charlton TR, Doucet M, Halbert CE, Islam F, Karim A, Kharlampieva E, Kilbey SM, Lin JYY, Phan MD, Smith GS, Sukhishvili SA, Thermer R, Veith GM, Watkins EB, Wilson D. Cinematic reflectometry using QIKR, the quite intense kinetics reflectometer. Rev Sci Instrum 2023; 94:013302. [PMID: 36725568 DOI: 10.1063/5.0122279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 11/14/2022] [Indexed: 06/18/2023]
Abstract
The Quite Intense Kinetics Reflectometer (QIKR) will be a general-purpose, horizontal-sample-surface neutron reflectometer. Reflectometers measure the proportion of an incident probe beam reflected from a surface as a function of wavevector (momentum) transfer to infer the distribution and composition of matter near an interface. The unique scattering properties of neutrons make this technique especially useful in the study of soft matter, biomaterials, and materials used in energy storage. Exploiting the increased brilliance of the Spallation Neutron Source Second Target Station, QIKR will collect specular and off-specular reflectivity data faster than the best existing such machines. It will often be possible to collect complete specular reflectivity curves using a single instrument setting, enabling "cinematic" operation, wherein the user turns on the instrument and "films" the sample. Samples in time-dependent environments (e.g., temperature, electrochemical, or undergoing chemical alteration) will be observed in real time, in favorable cases with frame rates as fast as 1 Hz. Cinematic data acquisition promises to make time-dependent measurements routine, with time resolution specified during post-experiment data analysis. This capability will be deployed to observe such processes as in situ polymer diffusion, battery electrode charge-discharge cycles, hysteresis loops, and membrane protein insertion into lipid layers.
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Affiliation(s)
- J F Ankner
- Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - R Ashkar
- Department of Physics, Virginia Tech, Blacksburg, Virginia 24061, USA
| | - J F Browning
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - T R Charlton
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M Doucet
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - C E Halbert
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - F Islam
- Neutron Technologies Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - A Karim
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, Texas 77204, USA
| | - E Kharlampieva
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | - S M Kilbey
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - J Y Y Lin
- Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M D Phan
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - G S Smith
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - S A Sukhishvili
- Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - R Thermer
- Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - G M Veith
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - E B Watkins
- Neutron Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - D Wilson
- Second Target Station Project, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Galuska LA, Muckley ES, Cao Z, Ehlenberg DF, Qian Z, Zhang S, Rondeau-Gagné S, Phan MD, Ankner JF, Ivanov IN, Gu X. SMART transfer method to directly compare the mechanical response of water-supported and free-standing ultrathin polymeric films. Nat Commun 2021; 12:2347. [PMID: 33879775 PMCID: PMC8058343 DOI: 10.1038/s41467-021-22473-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 03/09/2021] [Indexed: 11/23/2022] Open
Abstract
Intrinsic mechanical properties of sub-100 nm thin films are markedly difficult to obtain, yet an ever-growing necessity for emerging fields such as soft organic electronics. To complicate matters, the interfacial contribution plays a major role in such thin films and is often unexplored despite supporting substrates being a main component in current metrologies. Here we present the shear motion assisted robust transfer technique for fabricating free-standing sub-100 nm films and measuring their inherent structural-mechanical properties. We compare these results to water-supported measurements, exploring two phenomena: 1) The influence of confinement on mechanics and 2) the role of water on the mechanical properties of hydrophobic films. Upon confinement, polystyrene films exhibit increased strain at failure, and reduced yield stress, while modulus is reduced only for the thinnest 19 nm film. Water measurements demonstrate subtle differences in mechanics which we elucidate using quartz crystal microbalance and neutron reflectometry.
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Affiliation(s)
- Luke A Galuska
- Center for Optoelectronic Materials and Devices, School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Eric S Muckley
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Zhiqiang Cao
- Center for Optoelectronic Materials and Devices, School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Dakota F Ehlenberg
- Center for Optoelectronic Materials and Devices, School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Zhiyuan Qian
- Center for Optoelectronic Materials and Devices, School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Song Zhang
- Center for Optoelectronic Materials and Devices, School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg, MS, 39406, USA
| | - Simon Rondeau-Gagné
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, Canada, N9B3P4
| | - Minh D Phan
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - John F Ankner
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Ilia N Ivanov
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Xiaodan Gu
- Center for Optoelectronic Materials and Devices, School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg, MS, 39406, USA.
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5
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Aubry TJ, Winchell KJ, Salamat CZ, Basile VM, Lindemuth JR, Stauber JM, Axtell JC, Kubena RM, Phan MD, Bird MJ, Spokoyny AM, Tolbert SH, Schwartz BJ. Tunable Dopants with Intrinsic Counterion Separation Reveal the Effects of Electron Affinity on Dopant Intercalation and Free Carrier Production in Sequentially Doped Conjugated Polymer Films. Adv Funct Mater 2020; 30:2001800. [PMID: 32684909 PMCID: PMC7357248 DOI: 10.1002/adfm.202001800] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/02/2020] [Accepted: 04/06/2020] [Indexed: 06/11/2023]
Abstract
Carrier mobility in doped conjugated polymers is limited by Coulomb interactions with dopant counterions. This complicates studying the effect of the dopant's oxidation potential on carrier generation because different dopants have different Coulomb interactions with polarons on the polymer backbone. Here, dodecaborane (DDB)-based dopants are used, which electrostatically shield counterions from carriers and have tunable redox potentials at constant size and shape. DDB dopants produce mobile carriers due to spatial separation of the counterion, and those with greater energetic offsets produce more carriers. Neutron reflectometry indicates that dopant infiltration into conjugated polymer films is redox-potential-driven. Remarkably, X-ray scattering shows that despite their large 2-nm size, DDBs intercalate into the crystalline polymer lamellae like small molecules, indicating that this is the preferred location for dopants of any size. These findings elucidate why doping conjugated polymers usually produces integer, rather than partial charge transfer: dopant counterions effectively intercalate into the lamellae, far from the polarons on the polymer backbone. Finally, it is shown that the IR spectrum provides a simple way to determine polaron mobility. Overall, higher oxidation potentials lead to higher doping efficiencies, with values reaching 100% for driving forces sufficient to dope poorly crystalline regions of the film.
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Affiliation(s)
- Taylor J. Aubry
- Department of Chemistry and BiochemistryUniversity of California, Los AngelesLos AngelesCA90095‐1569USA
| | - K. J. Winchell
- Department of Chemistry and BiochemistryUniversity of California, Los AngelesLos AngelesCA90095‐1569USA
| | - Charlene Z. Salamat
- Department of Chemistry and BiochemistryUniversity of California, Los AngelesLos AngelesCA90095‐1569USA
| | - Victoria M. Basile
- Department of Chemistry and BiochemistryUniversity of California, Los AngelesLos AngelesCA90095‐1569USA
| | | | - Julia M. Stauber
- Department of Chemistry and BiochemistryUniversity of California, Los AngelesLos AngelesCA90095‐1569USA
| | - Jonathan C. Axtell
- Department of Chemistry and BiochemistryUniversity of California, Los AngelesLos AngelesCA90095‐1569USA
| | - Rebecca M. Kubena
- Department of Chemistry and BiochemistryUniversity of California, Los AngelesLos AngelesCA90095‐1569USA
| | - Minh D. Phan
- Neutron Scattering DivisionOak Ridge National LaboratoryOak RidgeTN37831USA
| | - Matthew J. Bird
- Chemistry DepartmentBrookhaven National LaboratoryUptonNY11973USA
| | - Alexander M. Spokoyny
- Department of Chemistry and BiochemistryUniversity of California, Los AngelesLos AngelesCA90095‐1569USA
- California NanoSystems InstituteUniversity of California, Los AngelesLos AngelesCA90095‐7227USA
| | - Sarah H. Tolbert
- Department of Chemistry and BiochemistryUniversity of California, Los AngelesLos AngelesCA90095‐1569USA
- California NanoSystems InstituteUniversity of California, Los AngelesLos AngelesCA90095‐7227USA
- Department of Materials Science and EngineeringUniversity of California, Los AngelesLos AngelesCA90095‐1595USA
| | - Benjamin J. Schwartz
- Department of Chemistry and BiochemistryUniversity of California, Los AngelesLos AngelesCA90095‐1569USA
- California NanoSystems InstituteUniversity of California, Los AngelesLos AngelesCA90095‐7227USA
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Abstract
Collagen is a skeleton of native extracellular matrix (ECM) that is known to provide mechanical and structural stability. In an attempt to develop a new connective cellular model with the surrounding ECM without further experimental complications, such as the reconstitution of ECM receptors, we designed the experiments and discovered that the fibrillogenesis of membrane-bound collagen is not spontaneous as it is in the form of free collagen in bulk solution. The confocal microscopic results suggest that cholesterol is a crucial component that facilitates the fibril formation on the membrane surface. In situ X-ray and neutron reflectivity on Langmuir monolayer and solid-supported lipid bilayer models, respectively, reveal two features of cholesterol effects on the collagen fibril formation. Mainly, cholesterol increases the lateral lipid headgroup separation on the membrane surface, which promotes the association degree of collagen monomers. It also enhances the elastic modulus of the membrane to impede membrane filtration by the collagen assemblies.
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Affiliation(s)
- Minh D Phan
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, Seoul 04107, Korea
| | - Keel Yong Lee
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, Seoul 04107, Korea
| | - Jumi Lee
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, Seoul 04107, Korea
| | - Sushil K Satija
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Kwanwoo Shin
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, Seoul 04107, Korea
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7
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Phan MD, Korotych OI, Brady NG, Davis MM, Satija SK, Ankner JF, Bruce BD. X-ray and Neutron Reflectivity Studies of Styrene-Maleic Acid Copolymer Interactions with Galactolipid-Containing Monolayers. Langmuir 2020; 36:3970-3980. [PMID: 32207953 DOI: 10.1021/acs.langmuir.9b03817] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Styrene-maleic acid (SMA) copolymers have recently gained attention for their ability to facilitate the detergent-free solubilization of membrane protein complexes and their native boundary lipids into polymer-encapsulated, nanosized lipid particles, referred to as SMALPs. However, the interfacial interactions between SMA and lipids, which dictate the mechanism, efficiency, and selectivity of lipid and membrane protein extraction, are barely understood. Our recent finding has shown that SMA 1440, a chemical derivative of the SMA family with a functionalized butoxyethanol group, was most active in galactolipid-rich membranes, as opposed to phospholipid membranes. In the present work, we have performed X-ray reflectometry (XRR) and neutron reflectometry (NR) on the lipid monolayers at the liquid-air interface followed by the SMA copolymer adsorption. XRR and Langmuir Π-A isotherms captured the fluidifying effect of galactolipids, which allowed SMA copolymers to infiltrate easily into the lipid membranes. NR results revealed the detailed structural arrangement of SMA 1440 copolymers within the membranes and highlighted the partition of butoxyethanol group into the lipid tail region. This work allows us to propose a possible mechanism for the membrane solubilization by SMA.
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Affiliation(s)
- Minh D Phan
- Large-Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Olena I Korotych
- Department of Biochemistry, and Cellular, and Molecular Biology, University of Tennessee at Knoxville, Knoxville, Tennessee 37966, United States
| | - Nathan G Brady
- Department of Biochemistry, and Cellular, and Molecular Biology, University of Tennessee at Knoxville, Knoxville, Tennessee 37966, United States
| | - Madeline M Davis
- Department of Biochemistry, and Cellular, and Molecular Biology, University of Tennessee at Knoxville, Knoxville, Tennessee 37966, United States
| | - Sushil K Satija
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - John F Ankner
- Large-Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Barry D Bruce
- Department of Biochemistry, and Cellular, and Molecular Biology, University of Tennessee at Knoxville, Knoxville, Tennessee 37966, United States
- Department of Microbiology, University of Tennessee at Knoxville, Knoxville, Tennessee 37966, United States
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Radwan RW, Evans MD, Davies M, Harris DA, Beynon J, Hatcher O, Bose P, Lucas MG, Featherstone J, Khot U, Chandrasekaran TV, Carr ND, Gwynne S, Drew P, Phan MD. Pelvic exenteration for advanced malignancy in elderly patients. Br J Surg 2015; 103:e115-9. [DOI: 10.1002/bjs.10058] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 10/13/2015] [Accepted: 10/21/2015] [Indexed: 12/19/2022]
Abstract
Abstract
Background
Pelvic exenteration is an aggressive surgical procedure reserved for highly selected patients. Surgery in the elderly is often associated with increased morbidity and mortality. The aim of this study was to review outcomes following exenteration for advanced pelvic malignancy in this subgroup of patients.
Methods
All patients aged 70 years and over who underwent pelvic exenteration between 1999 and 2014 were included in the study. This comprised all primary rectal, gynaecological and bladder tumours. The primary outcome measure was 5-year overall survival. Secondary endpoints were postoperative morbidity and 30-day mortality.
Results
A total of 94 patients were included, with a median age of 76 (range 70–90) years. There were 65 rectal, 20 gynaecological and nine bladder tumours. The administration of neoadjuvant therapy was significantly different among tumour types (P = 0·002). A total of 32 patients (34 per cent) developed postoperative complications, and there were six deaths (6 per cent) within 30 days of surgery. Median survival was 64 months for patients with rectal cancer, 30 months for those with gynaecological tumours and 15 months for those with bladder cancer. Five-year survival rates in these groups were 47, 31 and 22 per cent respectively (P = 0·023).
Conclusion
Given the possibility of long-term survival, pelvic exenteration should not be withheld on the grounds of advanced age alone.
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Affiliation(s)
- R W Radwan
- Swansea Pelvic Oncology Group, Abertawe Bro Morgannwg University Local Health Board, Swansea, UK
| | - M D Evans
- Swansea Pelvic Oncology Group, Abertawe Bro Morgannwg University Local Health Board, Swansea, UK
| | - M Davies
- Swansea Pelvic Oncology Group, Abertawe Bro Morgannwg University Local Health Board, Swansea, UK
| | - D A Harris
- Swansea Pelvic Oncology Group, Abertawe Bro Morgannwg University Local Health Board, Swansea, UK
| | - J Beynon
- Swansea Pelvic Oncology Group, Abertawe Bro Morgannwg University Local Health Board, Swansea, UK
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Pauschinger M, Phan MD, Doerner A, Kuehl U, Schwimmbeck PL, Poller W, Kandolf R, Schultheiss HP. Enteroviral RNA replication in the myocardium of patients with left ventricular dysfunction and clinically suspected myocarditis. Circulation 1999; 99:889-95. [PMID: 10027811 DOI: 10.1161/01.cir.99.7.889] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Previous studies dealing with the detection of enteroviral RNA in human endomyocardial biopsies have not differentiated between latent persistence of the enteroviral genome and active viral replication. Enteroviruses that are considered important factors for the development of myocarditis have a single-strand RNA genome of positive polarity that is transcribed by a virus-encoded RNA polymerase into a minus-strand mRNA during active viral replication. The synthesis of multiple copies of minus-strand enteroviral RNA therefore occurs only at sites of active viral replication but not in tissues with mere persistence of the viral genome. METHODS AND RESULTS We investigated enteroviral RNA replication versus enteroviral RNA persistence in endomyocardial biopsies of 45 patients with left ventricular dysfunction and clinically suspected myocarditis. Using reverse-transcriptase polymerase chain reaction in conjunction with Southern blot hybridization, we established a highly sensitive assay to specifically detect plus-strand versus minus-strand enteroviral RNA in the biopsies. Plus-strand enteroviral RNA was detected in endomyocardial biopsies of 18 (40%) of 45 patients, whereas minus-strand RNA as an indication of active enteroviral RNA replication was detected in only 10 (56%) of these 18 plus-strand-positive patients. Enteroviral RNA was not found in biopsies of the control group (n=26). CONCLUSIONS These data demonstrate that a significant fraction of patients with left ventricular dysfunction and clinically suspected myocarditis had active enteroviral RNA replication in their myocardium (22%). Differentiation between patients with active viral replication and latent viral persistence should be particularly important in future studies evaluating different therapeutic strategies. In addition, molecular genetic detection of enteroviral genome and differentiation between replicating versus persistent viruses is possible in a single endomyocardial biopsy.
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Affiliation(s)
- M Pauschinger
- Medical Clinic II, University Hospital Benjamin Franklin, Freie Universität Berlin, FRG
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