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Birch MT, Powalla L, Wintz S, Hovorka O, Litzius K, Loudon JC, Turnbull LA, Nehruji V, Son K, Bubeck C, Rauch TG, Weigand M, Goering E, Burghard M, Schütz G. History-dependent domain and skyrmion formation in 2D van der Waals magnet Fe 3GeTe 2. Nat Commun 2022; 13:3035. [PMID: 35641499 PMCID: PMC9156682 DOI: 10.1038/s41467-022-30740-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [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] [Received: 11/15/2021] [Accepted: 05/16/2022] [Indexed: 11/16/2022] Open
Abstract
The discovery of two-dimensional magnets has initiated a new field of research, exploring both fundamental low-dimensional magnetism, and prospective spintronic applications. Recently, observations of magnetic skyrmions in the 2D ferromagnet Fe3GeTe2 (FGT) have been reported, introducing further application possibilities. However, controlling the exhibited magnetic state requires systematic knowledge of the history-dependence of the spin textures, which remains largely unexplored in 2D magnets. In this work, we utilise real-space imaging, and complementary simulations, to determine and explain the thickness-dependent magnetic phase diagrams of an exfoliated FGT flake, revealing a complex, history-dependent emergence of the uniformly magnetised, stripe domain and skyrmion states. The results show that the interplay of the dominant dipolar interaction and strongly temperature dependent out-of-plane anisotropy energy terms enables the selective stabilisation of all three states at zero field, and at a single temperature, while the Dzyaloshinksii-Moriya interaction must be present to realise the observed Néel-type domain walls. The findings open perspectives for 2D devices incorporating topological spin textures. Fe3GeTe2, known as FGT, is a van der Waals magnetic material that was recently shown to host magnetic skyrmions. Here, Birch et al using both X-ray and electron microscopy to study the stability of skyrmions in FGT, revealing how the sample history can influence skyrmion formation
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Affiliation(s)
- M T Birch
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany.
| | - L Powalla
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany.
| | - S Wintz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - O Hovorka
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - K Litzius
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - J C Loudon
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK
| | - L A Turnbull
- Department of Physics, Durham University, Durham, DH1 3LE, UK
| | - V Nehruji
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - K Son
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany.,Department of Physics Education, Kongju National University, Gongju, 32588, South Korea
| | - C Bubeck
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - T G Rauch
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institut Nanospektroskopie, 12489, Berlin, Germany
| | - M Weigand
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institut Nanospektroskopie, 12489, Berlin, Germany
| | - E Goering
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - M Burghard
- Max Planck Institute for Solid State Research, 70569, Stuttgart, Germany
| | - G Schütz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
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Abstract
Developing the thermodynamics of nanoscale friction is needed in a wide range of tribological applications, where the key objective is to optimally control the energy dissipation. Here we show that modern stochastic thermodynamics allows us to interpret the measurements obtained by friction force microscopy, which is the standard tool for investigating the frictional properties of materials, in terms of basic thermodynamics concepts such as fluctuating work and entropy. We show that this allows the identification of the heat produced during the friction process as an unambiguous measure of thermodynamic irreversibility. We have applied this procedure to quantify the heat produced during the frictional sliding in a broad velocity range, and we observe velocity-dependent scaling behavior, which is useful for interpreting the experimental outcomes.
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Affiliation(s)
- P C Torche
- Engineering and Physical Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - P Nicolini
- Department of Control Engineering, Faculty of Electrical Engineering, Czech Technical University in Prague, Technicka 2, Prague 6, 16627, Czech Republic
| | - T Polcar
- Engineering and Physical Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - O Hovorka
- Engineering and Physical Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
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3
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Birch MT, Cortés-Ortuño D, Turnbull LA, Wilson MN, Groß F, Träger N, Laurenson A, Bukin N, Moody SH, Weigand M, Schütz G, Popescu H, Fan R, Steadman P, Verezhak JAT, Balakrishnan G, Loudon JC, Twitchett-Harrison AC, Hovorka O, Fangohr H, Ogrin FY, Gräfe J, Hatton PD. Real-space imaging of confined magnetic skyrmion tubes. Nat Commun 2020; 11:1726. [PMID: 32265449 PMCID: PMC7138844 DOI: 10.1038/s41467-020-15474-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [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: 09/18/2019] [Accepted: 03/13/2020] [Indexed: 11/23/2022] Open
Abstract
Magnetic skyrmions are topologically nontrivial particles with a potential application as information elements in future spintronic device architectures. While they are commonly portrayed as two dimensional objects, in reality magnetic skyrmions are thought to exist as elongated, tube-like objects extending through the thickness of the host material. The study of this skyrmion tube state (SkT) is vital for furthering the understanding of skyrmion formation and dynamics for future applications. However, direct experimental imaging of skyrmion tubes has yet to be reported. Here, we demonstrate the real-space observation of skyrmion tubes in a lamella of FeGe using resonant magnetic x-ray imaging and comparative micromagnetic simulations, confirming their extended structure. The formation of these structures at the edge of the sample highlights the importance of confinement and edge effects in the stabilisation of the SkT state, opening the door to further investigation into this unexplored dimension of the skyrmion spin texture.
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Affiliation(s)
- M T Birch
- Centre for Materials Physics, Durham University, Durham, DH1 3LE, UK
- Diamond Light Source, Didcot, OX11 0DE, UK
| | - D Cortés-Ortuño
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - L A Turnbull
- Centre for Materials Physics, Durham University, Durham, DH1 3LE, UK
| | - M N Wilson
- Centre for Materials Physics, Durham University, Durham, DH1 3LE, UK
| | - F Groß
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - N Träger
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - A Laurenson
- School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK
| | - N Bukin
- School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK
| | - S H Moody
- Centre for Materials Physics, Durham University, Durham, DH1 3LE, UK
| | - M Weigand
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
- Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Institut Nanospektroskopie, Kekuléstrasse 5, 12489, Berlin, Germany
| | - G Schütz
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - H Popescu
- Synchrotron SOLEIL, Saint Aubin, BP 48, 91192, Gif-sur-Yvette, France
| | - R Fan
- Diamond Light Source, Didcot, OX11 0DE, UK
| | - P Steadman
- Diamond Light Source, Didcot, OX11 0DE, UK
| | - J A T Verezhak
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - G Balakrishnan
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - J C Loudon
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK
| | - A C Twitchett-Harrison
- Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, UK
| | - O Hovorka
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - H Fangohr
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, SO17 1BJ, UK
- European XFEL GmbH, Holzkoppel 4, 22869, Schenefeld, Germany
| | - F Y Ogrin
- School of Physics and Astronomy, University of Exeter, Exeter, EX4 4QL, UK
| | - J Gräfe
- Max Planck Institute for Intelligent Systems, 70569, Stuttgart, Germany
| | - P D Hatton
- Centre for Materials Physics, Durham University, Durham, DH1 3LE, UK.
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Ruta S, Chantrell R, Hovorka O. Unified model of hyperthermia via hysteresis heating in systems of interacting magnetic nanoparticles. Sci Rep 2015; 5:9090. [PMID: 25766365 PMCID: PMC5155484 DOI: 10.1038/srep09090] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 02/09/2015] [Indexed: 12/31/2022] Open
Abstract
We present a general study of the frequency and magnetic field dependence of the specific heat power produced during field-driven hysteresis cycles in magnetic nanoparticles with relevance to hyperthermia applications in biomedicine. Employing a kinetic Monte-Carlo method with natural time scales allows us to go beyond the assumptions of small driving field amplitudes and negligible inter-particle interactions, which are fundamental to the applicability of the standard approach based on linear response theory. The method captures the superparamagnetic and fully hysteretic regimes and the transition between them. Our results reveal unexpected dipolar interaction-induced enhancement or suppression of the specific heat power, dependent on the intrinsic statistical properties of particles, which cannot be accounted for by the standard theory. Although the actual heating power is difficult to predict because of the effects of interactions, optimum heating is in the transition region between the superparamagnetic and fully hysteretic regimes.
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Affiliation(s)
- S. Ruta
- Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom
| | - R. Chantrell
- Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom
| | - O. Hovorka
- Faculty of Engineering and the Environment, University of Southampton, Highfield, Southampton, United Kingdom
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Moya X, Hueso LE, Maccherozzi F, Tovstolytkin AI, Podyalovskii DI, Ducati C, Phillips LC, Ghidini M, Hovorka O, Berger A, Vickers ME, Defay E, Dhesi SS, Mathur ND. Giant and reversible extrinsic magnetocaloric effects in La0.7Ca0.3MnO3 films due to strain. Nat Mater 2013; 12:52-58. [PMID: 23104152 DOI: 10.1038/nmat3463] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 09/18/2012] [Indexed: 06/01/2023]
Abstract
Large thermal changes driven by a magnetic field have been proposed for environmentally friendly energy-efficient refrigeration, but only a few materials that suffer hysteresis show these giant magnetocaloric effects. Here we create giant and reversible extrinsic magnetocaloric effects in epitaxial films of the ferromagnetic manganite La(0.7)Ca(0.3)MnO(3) using strain-mediated feedback from BaTiO(3) substrates near a first-order structural phase transition. Our findings should inspire the discovery of giant magnetocaloric effects in a wide range of magnetic materials, and the parallel development of nanostructured bulk samples for practical applications.
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Affiliation(s)
- X Moya
- Department of Materials Science, University of Cambridge, Cambridge, CB2 3QZ, UK
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Říhová B, Etrych T, Šírová M, Kovář L, Hovorka O, Kovář M, Benda A, Ulbrich K. Synergistic Action of Doxorubicin Bound to the Polymeric Carrier Based on N-(2-Hydroxypropyl)methacrylamide Copolymers through an Amide or Hydrazone Bond. Mol Pharm 2010; 7:1027-40. [DOI: 10.1021/mp100121g] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- B. Říhová
- Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20 Prague 4, Czech Republic, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic, and J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejskova 2155/3, 182 23 Prague 8, Czech Republic
| | - T. Etrych
- Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20 Prague 4, Czech Republic, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic, and J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejskova 2155/3, 182 23 Prague 8, Czech Republic
| | - M. Šírová
- Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20 Prague 4, Czech Republic, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic, and J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejskova 2155/3, 182 23 Prague 8, Czech Republic
| | - L. Kovář
- Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20 Prague 4, Czech Republic, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic, and J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejskova 2155/3, 182 23 Prague 8, Czech Republic
| | - O. Hovorka
- Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20 Prague 4, Czech Republic, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic, and J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejskova 2155/3, 182 23 Prague 8, Czech Republic
| | - M. Kovář
- Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20 Prague 4, Czech Republic, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic, and J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejskova 2155/3, 182 23 Prague 8, Czech Republic
| | - A. Benda
- Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20 Prague 4, Czech Republic, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic, and J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejskova 2155/3, 182 23 Prague 8, Czech Republic
| | - K. Ulbrich
- Institute of Microbiology, Academy of Sciences of the Czech Republic, v.v.i., Videnska 1083, 142 20 Prague 4, Czech Republic, Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Heyrovsky Sq. 2, 162 06 Prague 6, Czech Republic, and J. Heyrovsky Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejskova 2155/3, 182 23 Prague 8, Czech Republic
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7
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Fundová P, Filipovský T, Funda DP, Hovorka O, Holý R, Navara M, Tlaskalová-Hogenová H. Expression of IGF-1R and iNOS in nasal polyps; epithelial cell homeostasis and innate immune mechanisms in pathogenesis of nasal polyposis. Folia Microbiol (Praha) 2009; 53:558-62. [PMID: 19381485 DOI: 10.1007/s12223-008-0089-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 05/15/2008] [Indexed: 12/18/2022]
Abstract
Nasal polyps (NP), edematous projections of nasal mucosa (NM), are characterized by an inflammatory cellular infiltrate, however, little is known about etiopathogenesis of NP. Both innate immune mechanisms leading to activation of NF-kappaB and homeostasis of epithelial cells were implicated in the pathogenesis of NP. In this study we investigated the expression of insulin-like growth factor-1 receptor (IGF-1R) and inducible nitric-oxide synthase (iNOS) in NP compared to healthy NM in both the epithelial and stromal compartments. Using immunohistochemistry, frozen tissue sections of NP from 18 patients, and mucosal biopsy specimens of the inferior turbinate from 17 subjects were stained for IGF-1R and iNOS markers. Fluorescence microscopy and computerized image analysis revealed low numbers of IGF-1R-positive cells in all specimens. However, substantially increased numbers of IGF-1R-positive cells were found in NP compared to NM both within the epithelium (1.63 vs. 0.43) and stroma (3.27 vs. 1.03). Positivity for iNOS was detected within the epithelium of NP compared with NM. Numbers of iNOS-positive single cells were highly increased in NP vs. NM in both epithelial (3.83 vs. 1.08) and stromal (4.96 vs. 2.67) compartments. An increased iNOS expression within the epithelial layer as well as increased number of iNOS- and IGF-1R-positive cells in NP was observed. This suggests that innate immune mechanism, and to a lesser extent also growth and homeostasis of epithelial cells, may play a role in formation of NP.
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Affiliation(s)
- P Fundová
- Ear, Nose and Throat Department, Central Military Hospital, Prague, Czech Republic.
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8
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Chovanec P, Hovorka O, Novák K. Visualization of symbiotic tissue in intact root nodules of Vicia tetrasperma using GFP-marked Rhizobium leguminosarum bv. viciae. Folia Microbiol (Praha) 2008; 53:139-46. [PMID: 18500633 DOI: 10.1007/s12223-008-0020-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Revised: 09/25/2007] [Indexed: 11/29/2022]
Abstract
In rhizobial symbiosis with legume plant hosts, the symbiotic tissue in the root nodules of indeterminate type is localized to the basal part of the nodule where the symbiotic zones contain infected cells (IC) interspersed with uninfected cells (UC) that are devoid of rhizobia. Although IC are easily distinguished in nodule sections using standard histochemical techniques, their observation in intact nodules is hampered by nodule tissue characteristics. Tagging of Rhizobium leguminosarum bv. viciae strain 128C30 with a constitutively expressed gene for green fluorescent protein (nonshifted mutant form cycle3) in combination with the advantages of the tiny nodules formed by Vicia tetrasperma (L.) SCHREB . allowed for vital observation of symbiotic tissue using fluorescence microscopy. Separation of a red-shifted background channel and digital image stacking along z-axis enabled us to construct a nodule image in a classical fluorescence microscopy of nodules exceeding 1 mm in diameter. In parallel, visualization of nodule bacteria inside the symbiotic tissue by confocal microscopy at the excitation wavelength 488 nm clearly distinguished IC/UC pattern in the nodule virtual sections and revealed red-shifted fluorescence of nonrhizobial origin. This signal was located on the periphery of IC and increased with their degradation, thus suggesting accumulation of secondary metabolites, presumably flavonoids. The simultaneous detection of bacteria and secondary metabolites can be used for monitoring changes to intact nodule physiology in the model legumes. The advantage of V. tetrasperma as a suggested laboratory model for pea cross-inoculation group has been demonstrated.
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Affiliation(s)
- P Chovanec
- Institute of Microbiology, Academy of Sciences of the Czech Republic, 142 20, Prague, Czechia
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9
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Říhová B, Strohalm J, Hovorka O, Šubr V, Etrych T, Chytil P, Pola R, Plocová D, Bouček J, Ulbrich K. Doxorubicin release is not a prerequisite for the in vitro cytotoxicity of HPMA-based pharmaceuticals: In vitro effect of extra drug-free GlyPheLeuGly sequences. J Control Release 2008; 127:110-20. [DOI: 10.1016/j.jconrel.2008.01.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Revised: 01/02/2008] [Accepted: 01/07/2008] [Indexed: 11/29/2022]
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Abstract
Behavior of hysteretic trajectories for cyclical input is investigated as a function of the internal structure of a system modeled by the classical random network of binary spins. Different regimes of hysteretic behavior are discovered for different network connectivity and topology. Surprisingly, hysteretic trajectories which do not converge at all are observed. They are shown to be associated with the presence of specific topological elements in the network structure, particularly with the fully interconnected spin groups of size equal to or greater than 4.
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Affiliation(s)
- O Hovorka
- Electrical and Computer Engineering Department, Drexel University, Philadelphia, PA 19104, USA
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11
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Rihova B, Strohalm J, Kovar M, Mrkvan T, Subr V, Hovorka O, Sirova M, Rozprimova L, Kubackova K, Ulbrich K. Induction of Systemic Antitumour Resistance with Targeted Polymers. Scand J Immunol 2005; 62 Suppl 1:100-5. [PMID: 15953192 DOI: 10.1111/j.1365-3083.2005.01617.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Conjugates based on N-(2-hydroxypropyl)methacrylamide (HPMA) represent a new generation of antibody-targeted polymeric anticancer drugs with both cytotoxic and immunoprotecting/immunomobilizing activity. 20-90% of mice that are cured of EL4 mouse T-cell lymphoma, BCL1 mouse B-cell leukaemia and 38C13 mouse B-cell lymphoma by injection of doxorubicin-HPMA conjugate develop a long-lasting memory and systemic antitumour resistance. It is suggested that the main activity of the polymeric drug, directly after application is - due to the high level of the drug - of cytotoxic and cytostatic nature. Thereafter, long-term conjugates persist at low concentration in the circulation, which are capable of mobilizing the defence mechanisms of the host. Until now, seven patients with generalized carcinoma were treated with doxorubicin-HPMA-human-Ig conjugate. Disease stabilization, lasting from 6 to more than 18 months, was recorded.
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Affiliation(s)
- B Rihova
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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12
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Kalinová B, Svatos A, Kindl J, Hovorka O, Hrdý I, Kuldová J, Hoskovec M. Sex pheromone of horse-chestnut leafminer Camneraria ohridella and its use in a pheromone-based monitoring system. J Chem Ecol 2003; 29:387-404. [PMID: 12737265 DOI: 10.1023/a:1022686029051] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Gas chromatography combined with electroantennographic detection (GC-EAD), electroantennography (EAG), and wind-tunnel and field experiments were used to reinvestigate the composition of Cameraria ohridella (Lepidoptera, Gracillariidae, Lithocolletinae) sex pheromone. The GC-EAD experiments showed one EAD-active area corresponding to the major pheromone component. (8E,10Z)-tetradeca-8,10-dienal. The EAG experiments proved that (9E)-tetracedecenal and stereoisomers of (8E,10Z)-tetradeca-8,10-dienal exhibited significant electrophysiological activity and could, therefore, be considered as possible minor pheromone components. However, wind-tunnel and field experiments demonstrated that none of these compounds affect the efficacy of the main pheromone component. A monitoring system based on (8E,10Z)tetradeca-8,10-dienal was developed and used to study the flight activity of C. ohridella.
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Affiliation(s)
- B Kalinová
- Department of Natural Products, Insect Chemistry Group, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic.
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13
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Ríhová B, Strohalm J, Kubácková K, Jelínková M, Hovorka O, Kovár M, Plocová D, Sírová M, St'astný M, Rozprimová L, Ulbrich K. Acquired and specific immunological mechanisms co-responsible for efficacy of polymer-bound drugs. J Control Release 2002; 78:97-114. [PMID: 11772452 DOI: 10.1016/s0168-3659(01)00489-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present data providing new evidence that poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA)-bound drugs, unlike free drugs, have both cytostatic and immunomobilizing activity (CIA). Immediately after injection, due to the high level of the drug, the main activity of the polymeric conjugate is cytotoxic and cytostatic. Later on, long-term circulating PHPMA-bound drug, at concentrations lower than its minimal inhibitory levels, mobilizes the defense mechanisms of the host. Cytotoxic and cytostatic effects of drug-PHPMA were repeatedly confirmed. The following data support the concept of the immunomobilizing activity of the N-(2-hydroxypropyl)methacrylamide (HPMA) conjugates: (a) pre-treatment with free drugs (doxorubicin, cyclosporin A) accelerates the appearance of EL4 mouse T-cell lymphoma while a similar pre-treatment with doxorubicin-PHPMA induces limited but definitive mobilization of the host's defense mechanisms; (b) mice cured of EL4 mouse T-cell lymphoma, BCL1 mouse B-cell leukemia and 38C13 mouse B-cell lymphoma by injection of doxorubicin-PHPMA conjugate targeted with monoclonal antibodies (anti-Thy 1.2 for EL4, anti-B1 for BCL1 and anti-CD71 for 38C13) and re-transplanted with a lethal dose of the same cancer cells survive without any treatment considerably longer than control mice; (c) increased NK activity and anti-cancer antibody was detected only in animals treated with doxorubicin-PHPMA conjugate; and (d) considerably increased NK and LAK activity was seen in a human patient treated for generalized breast carcinoma with doxorubicin-PHPMA-IgG.
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Affiliation(s)
- B Ríhová
- Division of Immunology and Gnotobiology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20 4, Prague, Czech Republic.
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Ríhová B, Etrych T, Pechar M, Jelínková M, Stastný M, Hovorka O, Kovár M, Ulbrich K. Doxorubicin bound to a HPMA copolymer carrier through hydrazone bond is effective also in a cancer cell line with a limited content of lysosomes. J Control Release 2001; 74:225-32. [PMID: 11489498 DOI: 10.1016/s0168-3659(01)00320-0] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We have synthesized conjugates containing doxorubicin (DOX) bound to oligopeptide side chains (GlyGly or GlyPheLeuGly) of a water-soluble copolymer carrier based on poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) either through proteolytically (PK1 conjugates) [Synthetic polymeric drugs. U.S. Patent 5,037,883 (1991)] or hydrolytically cleavable bond (HC conjugates). Pharmacological efficacy of PK1 and HC conjugates was compared in vitro on murine: T-cell lymphoma EL4, B-cell leukemia BCL1, B-cell lymphoma 38C13, leukemia P388 and Con A-stimulated A/Ph splenocytes and on human: primary (SW480) and metastatic (SW620) colorectal cancer cell lines parent and transfected with Thy 1.2 gene [2] and on erythromyeloid leukemia cell line K 562. Inhibition of proliferation determined by 3[H]-thymidine incorporation revealed that the cytostatic effect of HC conjugates is up to two orders of magnitude higher compared to PK1 conjugates. In some cancer cell lines (SW 620/T, SW 480) the pharmacological activity of HC conjugates is in vitro comparable with the activity of the free drug. Unlike PK1 conjugates, HC conjugates with a lysosomally degradable spacer (GlyPheLeuGly) are less effective compared to HC conjugates containing lysosomally non-degradable spacer (GlyGly). Moreover, HC conjugates exert pronounced anti-proliferative activity also in erythroblastoid leukemia cell line K 562 with a limited content of lysosomes.
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Affiliation(s)
- B Ríhová
- Institute of Microbiology, Academy of Sciences of the Czech Republic, 14220 Prague 4, Czech Republic.
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15
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Říhová B, Strohalm J, Hoste K, Jelínková M, Hovorka O, Kovář M, Plocová D, Šírová M, Št'astný M, Schacht E, Ulbrich K. Immunoprotective therapy with targeted anticancer drugs. ACTA ACUST UNITED AC 2001. [DOI: 10.1002/1521-3900(200107)172:1<21::aid-masy21>3.0.co;2-c] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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16
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Abstract
Labial gland secretions of 22 males of the bumblebee Bombus pomorum, collected in the Czech Republic, were analysed separately for each individual. The secretions contained 70 compounds among which saturated and unsaturated hydrocarbons strongly dominated. The proportion of hydrocarbons in the secretion was unusually high (85-100%) compared to other bumblebee species studied so far (3-15%). Methyl and ethyl esters of fatty acids, known from many other bumblebee species, formed only minor components (less than 1% in sum) of the secretions of several B. pomorum individuals. No terpenic compounds, typical for males' marking secretion of many bumblebee species, were detected in B. pomorum. The absolute quantities of hydrocarbons present in the labial gland extracts were comparable with those usually present in other species. The composition of hydrocarbons found in the labial glands was different from the profile of the cuticular hydrocarbons. Despite our expectations in species exhibiting a regular patrolling and scent-marking behaviour, the labial gland extracts obtained from B. pomorum males were unusually low concentrated and their chemical composition was atypical with respect of the proportions of hydrocarbons when compared with other patrolling species. This is the first report on the analysis of the labial gland secretion of the B. pomorum males.
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Affiliation(s)
- I Valterová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic , Praha.
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17
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Ríhová B, Jelínková M, Strohalm J, St'astný M, Hovorka O, Plocová D, Kovár M, Dráberová L, Ulbrich K. Antiproliferative effect of a lectin- and anti-Thy-1.2 antibody-targeted HPMA copolymer-bound doxorubicin on primary and metastatic human colorectal carcinoma and on human colorectal carcinoma transfected with the mouse Thy-1.2 gene. Bioconjug Chem 2000; 11:664-73. [PMID: 10995209 DOI: 10.1021/bc9901696] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The aim of this study was to compare the potential of two plant lectins [peanut agglutinin (PNA) and wheat germ agglutinin (WGA)], monoclonal antibody (anti-Thy-1.2), its F(ab')(2) fragments, and galactosamine as targeting moieties bound to the polymer drug carrier to deliver a xenobiotic, doxorubicin, to selected cancer cell lines. We have used primary (SW 480, HT 29) and metastatic (SW 620) human colorectal cancer cell lines and a transfectant, genetically engineered SW 620 cell line with mouse gene Thy-1.2 (SW 620/T) to test the possibility of marking human cancer with xenogeneic mouse gene and use it for effective site-specific targeting. The targeting moieties and doxorubicin were conjugated to a water-soluble copolymer based on N-(2-hydroxypropyl)methacrylamide (HPMA) acting as a carrier responsible for controlled intracellular release of the targeted drug. FACS analysis showed a strong binding of WGA-FITC to all tested cell lines. Binding of PNA-FITC was considerably weaker. The in vitro antiproliferative effect of lectin-targeted HPMA carrier-bound doxorubicin evaluated as [(3)H]TdR incorporation reflected both the intensity of the binding and the different sensitivity of the tested cancer cells lines to doxorubicin. The antiproliferative effect of conjugates targeted with WGA was comparable to that with the conjugates targeted with the anti-Thy-1.2 monoclonal antibody or their F(ab')(2) fragments. The magnitude of the cytotoxic effect of HPMA-doxorubicin targeted with PNA was lower in all tested cell lines. While the conjugates with WGA were more cytotoxic, the conjugates with PNA were more specific as their binding is limited to cancer cells and to the sites of inflammation. Noncytotoxic conjugates with a very low concentration of doxorubicin and targeted with PNA, anti-Thy-1.2, or their F(ab')(2) fragments exerted in some lines (SW 480, SW 620) low mitogenic activity. The Thy-1.2 gene-transfected SW 620 metastatic colorectal cancer cell line was sensitive to the antiproliferative effect of Thy-1.2-targeted doxorubicin as was shown for the Thy-1. 2(+) EL4 cell line and for Thy-1.2(+) concanavalin A-stimulated mouse T lymphocytes. These results represent the first indication of the suitability of transfection of human cancer cells with selected targeting genes for site-specific therapy of malignancies.
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Affiliation(s)
- B Ríhová
- Institute of Microbiology, Academy of Sciences of the Czech Republic, 142 20 Prague 4-Krc, Czech Republic.
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18
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Ríhová B, Jelínková M, Strohalm J, Subr V, Plocová D, Hovorka O, Novák M, Plundrová D, Germano Y, Ulbrich K. Polymeric drugs based on conjugates of synthetic and natural macromolecules. II. Anti-cancer activity of antibody or (Fab')(2)-targeted conjugates and combined therapy with immunomodulators. J Control Release 2000; 64:241-61. [PMID: 10640661 DOI: 10.1016/s0168-3659(99)00140-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We provide data on in vivo targeting of the Thy 1.2 (CDw90) cell surface receptor expressed on neoplastic T cells, mouse EL4 T cell lymphoma. The targeting antibody and the anticancer drug, doxorubicin (DOX) were conjugated to a water-soluble copolymer based on N-(2-hydroxypropyl)methacrylamide (HPMA) acting as a carrier responsible for controlled intracellular release of the conjugated drug. The in vivo therapeutic efficacy of HPMA copolymer-bound DOX targeted with anti-EL4 antibody, polyclonal anti-thymocyte globulin (ATG), monoclonal anti-Thy 1.2 antibody or its F(ab')(2) fragment was compared with the efficacy of DOX conjugated to HPMA copolymer containing nonspecific IgG or bovine serum albumin (BSA). Anti-EL4 antibody-targeted conjugate caused a significant retardation of tumor growth and an extension of the life span of treated mice. The effect was comparable with that of HPMA copolymer-bound DOX targeted with ATG, anti-Thy 1.2 antibody or its F(ab')(2) fragment. However, considerable antitumor effect was seen also in conjugates targeted instead of specific antibodies with syngeneic nonspecific IgG or BSA. Patients with advanced cancer are often immunocompromised due to dysfunction of their immune system induced by cancer and cytotoxic drugs. A significant decrease of unwanted side-effects of targeted drugs against a number of vital organs was already documented. In this study we have compared immunotoxic effects of free DOX with those of its antibody-targeted form on NK cells and cytolytic T lymphocytes (CTLs) isolated from C57BL/10 mice bearing EL4 T cell lymphoma. In the same model we have tested the combination therapy with immunomodulators (beta-glucan or AM-2) injected together with targeted daunomycin. We have observed a significant protective effect of targeted DOX against NK cells and CTLs. Moreover, the data revealed that combination therapy considerably enhances antitumor efficacy of the targeted anticancer drug.
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Affiliation(s)
- B Ríhová
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Vídenská 1083, 142 20, Prague, Czech Republic
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19
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Martínková L, Patáková-Jůzlová P, Krent V, Kucerová Z, Havlícek V, Olsovský P, Hovorka O, Ríhová B, Veselý D, Veselá D, Ulrichová J, Prikrylová V. Biological activities of oligoketide pigments of Monascus purpureus. Food Addit Contam 1999; 16:15-24. [PMID: 11565571 DOI: 10.1080/026520399284280] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Rubropunctatin (1), monascorubrin (2), monascin (3) and ankaflavin (4) were purified from the mycelium of Monascus purpureus by flash chromatography on silica gel or reversed phase. Their embryotoxicity towards chicken embryos decreased in the order 2 > 1 > 3 > 4. The lower homologues 1 and 3 exhibited teratogenic effects on these organisms. Significant antibiotic activities against Bacillus subtilis and Candida pseudotropicalis were found with compounds 1 and 2. Immunosuppressive activity on mouse T-splenocytes was most pronounced with compounds 3 and 4. None of the compounds showed significant cytotoxic activity towards rat hepatocytes in vitro. Incubation of resting cells of M. purpureus with glycine afforded the dark-red compounds 5 and 6 where the pyran moiety of 1 and 2 changed into the N-substituted dihydropyridine moiety by replacement of the O-atom by the amino group of glycine. Compounds 5 and 6 were less biologically active than the major pigments 1-4.
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Affiliation(s)
- L Martínková
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague
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20
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Ríhová B, Trohalm J, Jelínková M, Stastný M, Hovorka O, Plocová D, Subr V, Ulbrich K. [Use of targeted drugs in antineoplastic and immunosuppressive therapy]. BRATISL MED J 1998; 99:439-46. [PMID: 9810768] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Affiliation(s)
- B Ríhová
- Mikrobiologický ústav Akademie vĕd Ceské republiky, Praha
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21
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Ríhová B, Srogl J, Jelínková M, Hovorka O, Buresová M, Subr V, Ulbrich K. HPMA-based biodegradable hydrogels containing different forms of doxorubicin. Antitumor effects and biocompatibility. Ann N Y Acad Sci 1997; 831:57-71. [PMID: 9616702 DOI: 10.1111/j.1749-6632.1997.tb52184.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Novel hydrogels based on N-(2-hydroxypropyl)methacrylamide (HPMA) and N,O-dimethacryloylhydroxylamine containing either doxorubicin (DOX) or water-soluble HPMA carrier-bound doxorubicin (P-GlyPheLeuGly-DOX; HPMA-DOX) were synthesized. The cross-linkages are susceptible to hydrolytic cleavage at physiological pH 7.4. Hydrogels in the form of rods or discs loaded with DOX or P-GlyLeuGly-DOX were implanted subcutaneously on the back of C57BL/10 mice on day 1 or on day 9 after inoculation with EL4 mouse T-cell lymphoma. The implanted hydrogels varied in the total load of DOX and rate of hydrolysis, which is dependent on the crosslinking density of the gels. The effect of HPMA based hydrogels containing DOX or HPMA carrier-bound DOX on tumor growth, animal life span, leukocyte populations in peripheral blood and bone marrow function evaluated by reticulocyte count was investigated. It was shown that: a) DOX and HPMA carrier-bound DOX administered in the form of HPMA-based hydrogels has better antitumor activity against experimental EL4 mouse T-cell lymphoma than soluble forms of the drug, b) hydrogels with shorter degradation rate (16-17 h) show better antitumor activity than hydrogels with longer duration time (48-52 h), c) the therapeutic effect of hydrogels with rate 16-17 h is directly related to the doxorubicin content; the higher the doxorubicin content, the better antitumor activity, d) the gel containing free doxorubicin showed significant antitumor activity even when implanted on day 9, i.e., in the time when tumor growth is already established, e) the hydrogel matrix without drug does not induce release of IL-1 or IL-6 into peripheral blood, does not induce formation of antibodies, and it is not mitogenic. Use of doxorubicin in the form of HPMA-based hydrogels allows a several-fold increase in the administered dose compared to soluble forms without detectable serious toxic side-effects.
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Affiliation(s)
- B Ríhová
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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22
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Říhová B, Jelínková M, Št'astný M, Hovorka O, Strohalm J, Šubr V, Plocová D, Ulbrich K. Antibody-targeted polymer-bound drugs. Immunol Lett 1997. [DOI: 10.1016/s0165-2478(97)85897-x] [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: 10/16/2022]
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23
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Sírová M, Hovorka O, Ríha I, Ríhová B, Baudys M, Kim SW, Skamene E. The in vivo antibody response against exogenous antigens is not influenced by the mouse Bcg (Nramp1) gene. Immunology 1997; 90:626-31. [PMID: 9176118 PMCID: PMC1456678 DOI: 10.1046/j.1365-2567.1997.00172.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The mouse Nramp1 (Bcg) gene on chromosome 1 exerts pleiotropic effects on macrophage function. The gene is known to affect presentation of mycobacteria, and other antigens in vitro, so that macrophages carrying the resistant Bcg allele better support the proliferation of antigen-specific T cells compared with macrophages of the sensitive phenotype. To determine whether the Bcg allele could affect in vivo the antibody response to antigens not related to mycobacterial infections, we tested the primary and secondary responses to sheep red blood cells (SRBC) and glycosylated bovine insulin (G-insulin) in two pairs of Bcg congenic strains: BALB/c (Bcgs) versus BALB/c.CD2 (Bcgr), and B10.A (Bcgs) versus B10Ar (Bcgr), and in C57BL/10ScSn (B10; Bcgs) and A/J (Bcgr) mice. Furthermore, the antigen-specific proliferative responses of T cells primed in vivo by protein antigens were also tested in Bcg congenic mice. We found no significant difference in in vivo antibody response either to SRBC or G-insulin between the Bcgr and Bcgs strains. The magnitude of in vitro antigen-specific proliferation of lymph node cells sensitized in vivo by hen egg lysozyme (HEL) or chicken ovalbumin (OVA) was also similar in Bcgs and Bcgr congenic mice. However, we have documented a higher antigen-presenting capacity of Bcgr macrophages in in vitro antigen-specific proliferation to OVA. Since the macrophages are the only cells in which the Nramp1 gene is expressed, we suggest that the activity of other types of antigen-presenting cells masks the effect of the Bcgr allele on antigen-presentation in vivo.
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Affiliation(s)
- M Sírová
- Division of Immunology and Gnotobiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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24
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Hoskovec M, Hovorka O, Kalinová B, Koutek B, Streinz L, Svatos A, Sebek P, Saman D, Vrkoc J. New mimics of the acetate function in pheromone-based attraction. Bioorg Med Chem 1996; 4:479-88. [PMID: 8733630 DOI: 10.1016/0968-0896(96)00029-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Several analogues of (Z)-8-dodecenyl acetate (1a), the major pheromone component of the Oriental fruit moth, Cydia molesta, with chloroformate and lactone functional groups in place of the acetate moiety, were synthesized and investigated for their biological activity at four evaluation levels, i.e. by electroantennography (EAG), electrosensillography (ESG), short-range sexual stimulation and activation in the flight-tunnel. We found very strict requirements on the shape as well as on the electron distribution of the acetate group for a productive interaction with the receptor. The behavioral results showed that, among the analogues investigated, the chloroformate 1b, alken-4-olide 2a and also dodecyl acetate (1c) possess significant (60-85%) inhibitory activities. Based on electrophysiological evidence demonstrating that (i) only 1b is competing with the major pheromone component 1a for the same receptor sites on the male antennal sensilla, (ii) 1c elicits moderate EAG but no ESG responses and (iii) 2a does not produce any electrophysiological response at all, three possible inhibitory mechanisms by which these analogues are acting could be distinguished.
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Affiliation(s)
- M Hoskovec
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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