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Noguere G, Scotta JP, Xu S, Farhi E, Ollivier J, Calzavarra Y, Rols S, Koza M, Marquez Damian JI. Temperature-dependent dynamic structure factors for liquid water inferred from inelastic neutron scattering measurements. J Chem Phys 2021; 155:024502. [PMID: 34266266 DOI: 10.1063/5.0055779] [Citation(s) in RCA: 3] [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] [Indexed: 11/14/2022] Open
Abstract
Temperature-dependent dynamic structure factors S(Q, ω) for liquid water have been calculated using a composite model, which is based on the decoupling approximation of the mean square displacement of the water molecules into diffusion and solid-like vibrational parts. The solid-like vibrational part Svib(Q, ω) is calculated with the phonon expansion method established in the framework of the incoherent Gaussian approximation. The diffusion part Sdiff(Q, ω) relies on the Egelstaff-Schofield translational diffusion model corrected for jump diffusions and rotational diffusions with the Singwi-Sjölander random model and Sears expansion, respectively. Systematics of the model parameters as a function of temperature were deduced from quasi-elastic neutron scattering data analysis reported in the literature and from molecular dynamics (MD) simulations relying on the TIP4P/2005f model. The resulting S(Q, ω) values are confronted by means of Monte Carlo simulations to inelastic neutron scattering data measured with IN4, IN5, and IN6 time-of-flight spectrometers of the Institut Laue-Langevin (ILL) (Grenoble, France). A modest range of temperatures (283-494 K) has been investigated with neutron wavelengths corresponding to incident neutron energies ranging from 0.57 to 67.6 meV. The neutron-weighted multiphonon spectra deduced from the ILL data indicate a slight overestimation by the MD simulations of the frequency shift and broadening of the librational band. The descriptive power of the composite model was suited for improving the comparison to experiments via Bayesian updating of prior model parameters inferred from MD simulations. The reported posterior temperature-dependent densities of state of hydrogen in H2O would represent valuable insights for studying the collective coupling interactions in the water molecule between the inter- and intramolecular degrees of freedom.
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Affiliation(s)
- G Noguere
- CEA, DES, IRESNE, Cadarache, F-13108 Saint Paul Les Durance, France
| | - J P Scotta
- CEA, DES, IRESNE, Cadarache, F-13108 Saint Paul Les Durance, France
| | - S Xu
- CEA, DES, IRESNE, Cadarache, F-13108 Saint Paul Les Durance, France
| | - E Farhi
- Institut Laue-Langevin, F-38042 Grenoble, France
| | - J Ollivier
- Institut Laue-Langevin, F-38042 Grenoble, France
| | - Y Calzavarra
- Institut Laue-Langevin, F-38042 Grenoble, France
| | - S Rols
- Institut Laue-Langevin, F-38042 Grenoble, France
| | - M Koza
- Institut Laue-Langevin, F-38042 Grenoble, France
| | - J I Marquez Damian
- Neutron Physics Departement and Instituto Balseiro, Centro Atomico Bariloche, CNEA, Bariloche, Argentina
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Abstract
The lattice dynamics of polycrystalline Mg(2)Ge and Mg(2)Si are compared using both microscopic and macroscopic measurements as well as theoretical calculations. The volume thermal expansion coefficient between 200 and 300 K was found to be 4.37(5) · 10(-5) K(-1) in Mg(2)Ge, compared to 3.69(5) · 10(-5) K(-1) in Mg(2)Si. Inelastic neutron scattering measurements yield densities of phonon states which are in line with theoretical calculations. The microscopic data were corroborated with macroscopic calorimetry measurements and provide quantified values for anharmonicity. The estimated macroscopic Grüneisen parameter is, γ(Mg(2)Si) = 1.17(5) and γ(Mg(2)Ge) = 1.46(5) at 295 K, in excellent agreement with Raman scattering data. Although the element specific mean force constants are practically the same, in Mg(2)Ge and Mg(2)Si, a mass homology relation alone cannot reproduce the difference in the partial densities of vibrational states in these compounds and differences in elemental bonding should be taken into account.
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Affiliation(s)
- D Bessas
- Jülich Centre for Neutron Science JCNS and Peter Grünberg Institut PGI, JARA-FIT, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany. Faculté des Sciences, Université de Liège, B-4000 Liège, Belgium. European Synchrotron Radiation Facility, F-38043, Grenoble, France
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3
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Sillrén P, Matic A, Karlsson M, Koza M, Maccarini M, Fouquet P, Götz M, Bauer T, Gulich R, Lunkenheimer P, Loidl A, Mattsson J, Gainaru C, Vynokur E, Schildmann S, Bauer S, Böhmer R. Liquid 1-propanol studied by neutron scattering, near-infrared, and dielectric spectroscopy. J Chem Phys 2014; 140:124501. [PMID: 24697453 DOI: 10.1063/1.4868556] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Liquid monohydroxy alcohols exhibit unusual dynamics related to their hydrogen bonding induced structures. The connection between structure and dynamics is studied for liquid 1-propanol using quasi-elastic neutron scattering, combining time-of-flight and neutron spin-echo techniques, with a focus on the dynamics at length scales corresponding to the main peak and the pre-peak of the structure factor. At the main peak, the structural relaxation times are probed. These correspond well to mechanical relaxation times calculated from literature data. At the pre-peak, corresponding to length scales related to H-bonded structures, the relaxation times are almost an order of magnitude longer. According to previous work [C. Gainaru, R. Meier, S. Schildmann, C. Lederle, W. Hiller, E. Rössler, and R. Böhmer, Phys. Rev. Lett. 105, 258303 (2010)] this time scale difference is connected to the average size of H-bonded clusters. The relation between the relaxation times from neutron scattering and those determined from dielectric spectroscopy is discussed on the basis of broad-band permittivity data of 1-propanol. Moreover, in 1-propanol the dielectric relaxation strength as well as the near-infrared absorbance reveal anomalous behavior below ambient temperature. A corresponding feature could not be found in the polyalcohols propylene glycol and glycerol.
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Affiliation(s)
- P Sillrén
- Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - A Matic
- Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - M Karlsson
- Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
| | - M Koza
- Institut Laue Langevin, 6, rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France
| | - M Maccarini
- Institut Laue Langevin, 6, rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France
| | - P Fouquet
- Institut Laue Langevin, 6, rue Jules Horowitz, BP 156, 38042 Grenoble Cedex 9, France
| | - M Götz
- Experimental Physics V, University of Augsburg, 86135 Augsburg, Germany
| | - Th Bauer
- Experimental Physics V, University of Augsburg, 86135 Augsburg, Germany
| | - R Gulich
- Experimental Physics V, University of Augsburg, 86135 Augsburg, Germany
| | - P Lunkenheimer
- Experimental Physics V, University of Augsburg, 86135 Augsburg, Germany
| | - A Loidl
- Experimental Physics V, University of Augsburg, 86135 Augsburg, Germany
| | - J Mattsson
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - C Gainaru
- Fakultät für Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - E Vynokur
- Fakultät für Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - S Schildmann
- Fakultät für Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - S Bauer
- Fakultät für Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
| | - R Böhmer
- Fakultät für Physik, Technische Universität Dortmund, 44221 Dortmund, Germany
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Bove LE, Klotz S, Strässle T, Koza M, Teixeira J, Saitta AM. Translational and rotational diffusion in water in the Gigapascal range. Phys Rev Lett 2013; 111:185901. [PMID: 24237539 DOI: 10.1103/physrevlett.111.185901] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Indexed: 06/02/2023]
Abstract
First measurements of the self-dynamics of liquid water in the GPa range are reported. The GPa range has here become accessible through a new setup for the Paris-Edinburgh press specially conceived for quasielastic neutron scattering studies. A direct measurement of both the translational and rotational diffusion coefficients of water along the 400 K isotherm up to 3 GPa, corresponding to the melting point of ice VII, is provided and compared with molecular dynamics simulations. The translational diffusion is observed to strongly decrease with pressure, though its variation slows down for pressures higher than 1 GPa and decouples from that of the shear viscosity. The rotational diffusion turns out to be insensitive to pressure. Through comparison with structural data and molecular dynamics simulations, we show that this is a consequence of the rigidity of the first neighbors shell and of the invariance of the number of hydrogen bonds of a water molecule under high pressure. These results show the inadequacy of the Stokes-Einstein-Debye equations to predict the self-diffusive behavior of water at high temperature and high pressure, and challenge the usual description of hot dense water behaving as a simple liquid.
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Affiliation(s)
- L E Bove
- IMPMC, CNRS-UMR 7590, Université Pierre & Marie Curie, 75252 Paris, France and Ecole Polytech Fed Lausanne, Inst Condensed Matter Phys, EPSL, CH-1015 Lausanne, Switzerland
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Iqbal O, Jeske W, Hoppensteadt D, Koza M, Walenga JM, Fareed J, Moncada R. Procoagulant and anticoagulant effects of intravascular contrast media as assessed by thromboelastography. Semin Thromb Hemost 2012; 21 Suppl 4:86-90. [PMID: 8747695 DOI: 10.1055/s-0032-1313628] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- O Iqbal
- Department of Pathology, Loyola University, Chicago, Illinois, USA
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Gerstl C, Schneider GJ, Fuxman A, Zamponi M, Frick B, Seydel T, Koza M, Genix AC, Allgaier J, Richter D, Colmenero J, Arbe A. Quasielastic Neutron Scattering Study on the Dynamics of Poly(alkylene oxide)s. Macromolecules 2012. [DOI: 10.1021/ma3003399] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- C. Gerstl
- Jülich Centre
for Neutron Science (JCNS 1) and Institut for Complex Systems (ICS
1), Forschungszentrum Jülich GmbH, D−52425 Jülich, Germany
- Jülich Centre for Neutron Science (JCNS 1), Outstation at FRM II, 85747 Garching, Germany
| | - G. J. Schneider
- Jülich Centre for Neutron Science (JCNS 1), Outstation at FRM II, 85747 Garching, Germany
| | - A. Fuxman
- Jülich Centre for Neutron Science (JCNS 1), Outstation at FRM II, 85747 Garching, Germany
| | - M. Zamponi
- Jülich Centre for Neutron Science (JCNS 1), Outstation at FRM II, 85747 Garching, Germany
| | - B. Frick
- Institut Laue−Langevin, BP 156, 38042 Grenoble Cedex 9, France
| | - T. Seydel
- Institut Laue−Langevin, BP 156, 38042 Grenoble Cedex 9, France
| | - M. Koza
- Institut Laue−Langevin, BP 156, 38042 Grenoble Cedex 9, France
| | - A.-C. Genix
- Laboratoire Charles Coulomb, UMR 5221, CNRS and Université Montpellier 2, 34095 Montpellier,
France
| | - J. Allgaier
- Jülich Centre
for Neutron Science (JCNS 1) and Institut for Complex Systems (ICS
1), Forschungszentrum Jülich GmbH, D−52425 Jülich, Germany
| | - D. Richter
- Jülich Centre
for Neutron Science (JCNS 1) and Institut for Complex Systems (ICS
1), Forschungszentrum Jülich GmbH, D−52425 Jülich, Germany
- Jülich Centre for Neutron Science (JCNS 1), Outstation at FRM II, 85747 Garching, Germany
| | - J. Colmenero
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San
Sebastián, Spain
- Departamento de Física de Materiales (UPV/EHU), Apartado 1072, 20080 San Sebastián, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 San Sebastián,
Spain
| | - A. Arbe
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San
Sebastián, Spain
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7
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Lauter H, Apaja V, Kalinin I, Kats E, Koza M, Krotscheck E, Lauter VV, Puchkov AV. Observation of a superfluid component within solid helium. Phys Rev Lett 2011; 107:265301. [PMID: 22243164 DOI: 10.1103/physrevlett.107.265301] [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: 09/24/2010] [Revised: 04/11/2011] [Indexed: 05/31/2023]
Abstract
We demonstrate by neutron scattering that a localized superfluid component exists at high pressures within solid helium in aerogel. Its existence is deduced from the observation of two sharp phonon-roton spectra which are clearly distinguishable from modes in bulk superfluid helium. These roton excitations exhibit different roton gap parameters than the roton observed in the bulk fluid at freezing pressure. One of the roton modes disappears after annealing the samples. Comparison with theoretical calculations suggests that the model that reproduces the observed data best is that of superfluid double layers within the solid and at the helium-substrate interface.
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Affiliation(s)
- H Lauter
- Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Bal U, Kanyilmaz S, Yildirir A, Aydinalp A, Kaynar G, Koza M, Muderrisoglu H. MS346 COULD PLASMA LEVEL OF ASYMMETRIC DIMETILARJININ BE A MARKER FOR STENT RESTENOSIS? ATHEROSCLEROSIS SUPP 2010. [DOI: 10.1016/s1567-5688(10)70847-3] [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: 11/26/2022]
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9
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Abstract
Abstract
The structural transformation of different high-density amorphous (HDA) ice modifications into the low-density amorphous (LDA) ice is studied by small-angle neutron scattering (SANS) techniques. All experiments have been performed at stationary conditions allowing to collect detailed information not only on the SANS formfactor but also on its time evolution and, hence, the kinetics governing the transformation process. A parametrization of the SANS formfactor by a superposition of the Debye-Bueche formfactor, characterizing a non-particulate two phase mixture, and a Porod-limit scattering formfactor is carried out successfully. The Porod-limit scattering indicates the presence of sharp interfaces and surfaces present in the sample material. Interpreting this signal as due to a grainy consistency of the amorphous samples grain sizes of the order of at least some micrometers can be approximated. The Debye-Bueche ansatz accounts for the formation of a transient pronounced signal on mesoscopic length scales. Its analysis results in an average domain size of 12–16 Å characterizing a hypothetical two phase mixture in its state of strongest intermixture, i.e., strongest heterogeneity. Interpretation of the Debye-Bueche formfactor by the Porod invariant results in a sample contrast that is by a factor of about 4 smaller than a hypothetical first-order transition between any modification of HDA and LDA. This statement is valid for an unstrained two-phase system separated by sharp interfaces. A detailed discussion is given which tries to set the present results into a more realistic context.
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11
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Renker B, Bohnen KB, Heid R, Ernst D, Schober H, Koza M, Adelmann P, Schweiss P, Wolf T. Strong renormalization of phonon frequencies in Mg(1-x)Al(x)B2. Phys Rev Lett 2002; 88:067001. [PMID: 11863842 DOI: 10.1103/physrevlett.88.067001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2001] [Indexed: 05/23/2023]
Abstract
The phonon spectrum of Mg(1-x)Al(x)B2 shows a strong dependence on the aluminum content x. This is experimentally demonstrated by both Raman and inelastic neutron scattering and theoretically predicted by first-principles calculations. The observed changes in the phonon spectrum are put into perspective with respect to the superconducting properties within this family of materials.
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Affiliation(s)
- B Renker
- Forschungszentrum Karlsruhe, IFP, P.O.B. 3640, D-76021 Karlsruhe, Germany
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Martinez LP, Koza M. Anesthesia-related periodic involuntary movement in an obstetrical patient for cesarean section under epidural anesthesia: a case report. AANA J 1997; 65:150-153. [PMID: 9233109] [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: 05/22/2023]
Abstract
Anesthesia-related periodic involuntary movements in a patient with regional anesthesia or etomidate anesthesia can be alarming. This case report describes anesthesia-related periodic involuntary movement in a patient undergoing cesarean section with epidural anesthesia. The anesthesia-related periodic involuntary movement occurred postoperatively in the recovery room. The discussion includes a brief review of spinal cord anatomy and physiology, as well as a review of the literature describing similar events.
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Affiliation(s)
- L P Martinez
- University of New Mexico, Department of Anesthesiology and Critical Care Medicine, Albuquerque, USA
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Abstract
In an in vitro study the effect of various thrombin inhibitors (argatroban, efegatran, DuP 714, recombinant hirudin and PEG-hirudin) on platelet activation in whole blood was investigated. Blood was drawn from normal human volunteers using the double syringe technique without use of a tourniquet to avoid autoaggregation of platelets. Blood was anticoagulated with either argatroban, efegatran, DuP 714, hirudin or PEG-hirudin at final concentrations of 10 micrograms/ml. Blood samples were then incubated at 37 degrees C either with saline, r-tissue factor, arachidonic acid, adenosine diphosphate or collagen. At definite times (1, 2.5, 5, 10 min) aliquots were taken and after various steps of fixative procedure the percentage of platelet activation was measured using fluorescent monoclonal antibodies to platelet surface receptors GPIIIa (CD-61) and P-selectin (CD-62). Flow cytometric analysis showed a platelet activation after all agonists used. All thrombin inhibitors studied caused a nearly complete inhibition of r-tissue factor-mediated platelet activation. In contrast, after activation with the other agonists an increased percent CD-62 expression was found with a maximum after 2.5 to 5 min. The results show that in whole blood thrombin inhibitors are effective in preventing platelet activation induced by r-tissue factor. The formation of active serine proteases including thrombin may be effectively inhibited by these agents. The observations further suggest that while thrombin inhibitors may control serine proteases, these agents do not inhibit the activation of platelets mediated by other agonists.
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Affiliation(s)
- B Kaiser
- Friedrich Schiller University Jena, Center for Vascular Biology and Medicine, Erfurt, Germany
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16
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Fareed J, Hoppensteadt D, Iyer L, Koza M, Walenga JM, Bermes E. Impact of biotechnology in the diagnostic and therapeutic management of cardiovascular disorders. Adv Exp Med Biol 1995; 369:99-110. [PMID: 7598021 DOI: 10.1007/978-1-4615-1957-7_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Although biotechnology has been useful in the development of new diagnostic methods and drugs for the management of cardiovascular disorders, there are several issues which raise certain questions on the global use of biotechnology based drugs and diagnostic methods (Piascik, 1991; Fareed, 1993a; Fareed, 1994a). The cost is rather prohibitive in the development of this type of technology. Most diagnostic methods and drugs developed utilizing biotechnology based methods are relatively expensive. The second important consideration is the equivalence of the newer biotechnology derived drugs to the natural products. Many of the biotechnology derived drugs are obtained in prokaryotic systems (E. coli). Post-transcriptional modifications such as glycosylation are often important in determining the function of various proteins. On the other hand, biotechnology based diagnostic methods exhibit somewhat different specificity in comparison to conventional methods. Thus, it is rather important to assess the developments in this area in a careful manner. Furthermore, validation of the clinical, diagnostic and therapeutic efficacy of biotechnology derived diagnostic devices and drugs is a prerequisite for their use in cardiovascular medicine.
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Affiliation(s)
- J Fareed
- Department of Pathology, Loyola University Medical Center, Maywood, IL 60153, USA
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Messmore HL, Koza M, Farid S, Wehrmacher WH. Utility of the Heptest and a chromogenic substrate method to assess anticoagulation in patients refractory to heparinization by the activated partial thromboplastin time method. Semin Thromb Hemost 1994; 20:351-2. [PMID: 7899867 DOI: 10.1055/s-2007-1001926] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- H L Messmore
- Loyola University Stritch School of Medicine, Maywood, IL 60153
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Iyer L, Koza M, Iqbal O, Calabria R, Fareed J. Studies on the pharmacokinetics and pharmacodynamics of recombinant hirudin (rHV2-Lys 47) after intravenous and subcutaneous administration in dogs. Thromb Res 1993; 69:259-69. [PMID: 8475476 DOI: 10.1016/0049-3848(93)90023-h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [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: 01/31/2023]
Abstract
In recent years, the pharmacological and biochemical characterization of hirudins has taken a major upswing due to the availability of this natural polypeptide in recombinant form. Despite this, the current knowledge on the pharmacokinetics and pharmacodynamics of recombinant hirudin (rH) appears to be incomplete. The present study was designed to investigate the relationship between plasma concentrations of rH with corresponding antithrombin responses after intravenous (i.v.) and subcutaneous (s.c.) administration in dogs. Four male, Mongrel dogs were each injected with an i.v. (bolus) dose (1 mg/kg) of one specific variant of rH, i.e. rH with a lysine residue in position 47 (rHV2-Lys 47). The dogs were injected with a s.c. dose (1 mg/kg) of rHV2-Lys 47 after one week. After each dose, blood was collected at different time intervals, plasma separated and stored at -70 degrees C. Plasma concentrations of rHV2-Lys 47 were determined using an enzyme-linked immunosorbent assay (ELISA) method and pharmacokinetic parameters were determined using standard non-compartmental methods. The ex vivo antithrombin activity of the drug was measured using activated partial thromboplastin time (APTT), calcium-thrombin time (Ca++TT) and a chromogenic anti-IIa assay. The results from this study indicate that the pharmacokinetic behavior of rHV2-Lys 47 is strongly influenced by the route of administration. In all three functional assays used, a significant correlation was obtained after i.v. administration between plasma concentrations and corresponding responses over the time period of the study when compared to s.c. administration. The results are indicative of a probable structural and functional modification of this rH variant after s.c. administration which may be responsible for the altered pharmacokinetics and pharmacodynamics after s.c. dosing.
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Affiliation(s)
- L Iyer
- Department of Pharmacology, Loyola University Medical Center, Maywood, IL 60153
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Iyer L, Shavit J, Koza M, Calabria R, Moran S, Fareed J. Alteration of pharmacokinetics and pharmacodynamics of recombinant hirudin (rHV2-Lys 47) after repeated intravenous administration in dogs. Thromb Res 1993; 69:59-70. [PMID: 8465275 DOI: 10.1016/0049-3848(93)90003-7] [Citation(s) in RCA: 13] [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: 01/30/2023]
Abstract
Native hirudin is a heterogenous polypeptide obtained from the medicinal leech, Hirudo medicinalis. Recent advances in molecular biological techniques have led to the availability of large amounts of hirudin in the recombinant form. Recombinant hirudins (rH) are currently being investigated for potential use in the prophylaxis and treatment of deep venous thrombosis (DVT), in disseminated intravascular coagulation (DIC) and during cardiovascular bypass surgery. In this study, one specific variant of rH with a lysine residue in position 47 (rHV2-Lys 47) was administered in dogs in a multiple dose regimen of 2 mg/kg (i.v. bolus) for three weeks with a dosing interval of one week. After each dose, blood samples were collected at regular time intervals, plasma separated and stored at -4 degrees C. Concentrations of rHV2-Lys 47 in each sample were determined using an enzyme-linked immunosorbent assay (ELISA). Ex vivo antithrombin responses measured included activated partial thromboplastin time (APTT), calcium-thrombin time (Ca++TT-10 NIH units/ml) and a chromogenic anti-IIa assay. It was the purpose of this study to detect any sensitization or desensitization of antithrombin responses when rHV2-Lys 47 is used in a repeated fashion such as would be expected in the prophylaxis of DVT. The results indicated that there was no attenuation in the responses; however, there was a sensitization of response as measured by the Ca++TT (10 NIH units/ml). These findings could have major implications in the clinical use of rH where this drug is expected to be used in a multiple dose regimen.
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Affiliation(s)
- L Iyer
- Department of Pharmacology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL
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Darouiche R, Wright C, Hamill R, Koza M, Lewis D, Markowski J. Eradication of colonization by methicillin-resistant Staphylococcus aureus by using oral minocycline-rifampin and topical mupirocin. Antimicrob Agents Chemother 1991; 35:1612-5. [PMID: 1929333 PMCID: PMC245228 DOI: 10.1128/aac.35.8.1612] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.8] [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: 12/29/2022] Open
Abstract
In an attempt to control the spread of methicillin-resistant Staphylococcus aureus (MRSA) within a spinal cord injury unit, we investigated the mode of transmission and implemented a multidisciplinary approach for control that consisted of grouping of patients into cohorts, contact isolation, and antibiotics. Surveillance cultures of patients and nose and hand cultures of medical personnel were performed. Of 11 colonized patients, 6 had MRSA isolates that shared a similar plasmid profile and antibiogram, raising the possibility of interpatient spread of the organism. Medical personnel had no evident role in transmitting MRSA. All patients' pretherapy MRSA isolates were susceptible to minocycline and, except for one, to rifampin. Time-kill studies showed an indifferent interaction of these two antibiotics. Ten colonized patients received a 2-week oral course of 100 mg of minocycline twice daily and 600 mg of rifampin once daily, while the 11th patient was treated for only 1 week. Patients with colonization of the nares also had twice daily nasal application of 2% mupirocin for 5 days. Colonization with MRSA cleared in 10 of 11 patients (91%) and 20 of 21 sites (95%). When the individual circumstances of a medical facility justify eradication of MRSA colonization, a multidisciplinary approach that includes antibiotic therapy with oral minocycline and rifampin, along with topical mupirocin for those with nasal carriage, may be successful.
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Affiliation(s)
- R Darouiche
- Medical Service, Veterans Affairs Medical Center, Houston, Texas
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Hoppensteadt D, Koza M, Pifarre R, Fareed J, Walenga J. Vergleichende Studien verschiedener Methoden zur Bestimmung von r-Hirudin in vitro. Hamostaseologie 1991. [DOI: 10.1055/s-0038-1660295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
ZusammenfassungZur Bestimmung von rekombinantem (r-)Hirudin stehen auf der Gerinnselbildung beruhende, amidolytische, immunologische und physikochemische Techniken zur Verfügung. Die globalen Tests wie PTZ, aPTT und Heptest reagieren nicht ausreichend auf r-Hirudin in dem Bereich von 0,5 bis 10,0 μg/ml, in dem volle Antikoagulation erreicht wird, wie dies aus Thrombosemodellen im Tierversuch hervorgeht. Der Thrombinzeittest mit 10 E/ml war sehr empfindlich auf r-Hirudin, die Kalzium-Thrombin-Gerinnungszeitmit 10 E/ml reagierte dosisabhängig in einem Bereich von 0,15 bis 10,0 μg/ml. Vollblutgerinnungstests wie ACT und Thrombelastographie messen den r-Hirudinspiegel bis 25 μg/ml effektiv. Der amidolytische Anti-Faktor-IIa-Test, spezifisch für die Beurteilung der direkten Thrombinhemmung, war besonders dann sehr effektiv, wenn das Probenvolumen im Verhältnis zur Thrombinkonzentration zur Bestimmung höherer r-Hirudinkonzentrationen vermindert wurde. Dieser Test könnte für die Qualitätskontrolle geeignet sein, da er biochemisch definiert ist und die Reagenzien leicht standardisiert werden können. Thrombinbildungstests auf der Basis synthetischer Substrate zeigten eine nur geringe Wirkung von r-Hirudin; hingegen wiesen Tests, die auf der Bildung von Thrombin-Antithrombin-Komplexen und auf der Bildung von Prothrombinfragment F1+2 beruhen, eine dosisabhängige Reaktion auf. Immunologische Methoden (ELISA) sind in der Entwicklung. Da diese Tests sowohl das gebundene als auch das freie r-Hirudin bestimmen und da sie bereits auf Submikrogrammspiegel empfindlich sind, dürften sie nur für die direkte Bestimmung der absoluten r-Hirudinspiegel, nicht aber für die Überwachung der klinischen Antikoagulation geeignet sein.
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Walenga JM, Hoppensteadt D, Koza M, Pifarre R, Fareed J. Comparative studies on various assays for the laboratory evaluation of r-hirudin. Semin Thromb Hemost 1991; 17:103-12. [PMID: 1771408 DOI: 10.1055/s-2007-1002597] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [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: 12/28/2022]
Abstract
Several laboratory methods are available to measure r-hirudin, including clot-based, amidolytic, immunologic, and physicochemical techniques. The global tests, such as the PT, APTT, and Heptest, did not show an adequate response to r-hirudin in the range of 0.5 to 10.0 micrograms/ml, where full anticoagulation is achieved, as determined by animal models of thrombosis. The 10 U/ml thrombin time assay was very sensitive to r-hirudin, whereas the 10 U/ml calcium thrombin time gave a dose-dependent response from 0.15 to 10.0 micrograms/ml. Whole blood clotting assays (ACT, TEG) effectively measured r-hirudin levels up to 25 micrograms/ml. The amidolytic anti-Factor IIa assay, specific for evaluating direct thrombin inhibition, was very effective, particularly when modified to decrease the sample: thrombin ratio for higher r-hirudin concentrations. This assay may be useful in quality control, since it is biochemically defined and reagents are easily standardized. Thrombin generation assays based on synthetic substrates showed limited effect of r-hirudin; however, assays based on TAT complex and prothrombin fragment F1+2 generation showed a dose-dependent response. Immunologic methods (ELISA) are under development. Since these assays measure both complexed and noncomplexed hirudin, and since they are only sensitive to submicrogram levels, they may only be useful for the direct quantitation of absolute levels of r-hirudin but not for monitoring clinical anticoagulation. Thus, thrombin-based clotting, amidolytic, and immunologic assays can be used to evaluate and measure r-hirudin. However, optimization of each assay to respond to high and low concentrations of r-hirudin and their application to clinical monitoring, batch control, and standardization needs to be determined.
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Affiliation(s)
- J M Walenga
- Department of Thoracic Cardiovascular Surgery, Loyola University Medical Center, Maywood, Illinois 60153
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Walenga JM, Bakhos M, Messmore HL, Koza M, Wallock M, Orfei E, Fareed J, Pifarre R. Comparison of recombinant hirudin and heparin as an anticoagulant in a cardiopulmonary bypass model. Blood Coagul Fibrinolysis 1991; 2:105-11. [PMID: 1772977 DOI: 10.1097/00001721-199102000-00017] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Recombinant (r) hirudin is a potent thrombin-specific inhibitor originally derived from the natural hirudin of the leech (Hirudo medicinalis). We have studied the efficacy of r-hirudin compared to heparin in a dog model of cardiopulmonary bypass (CPB) surgery. Two administration regimens were used for r-hirudin: Group I received 1.0 mg/kg intracardiac (i.c.) bolus then intravenous (i.v.) bolus at 30 min (n = 10); Group II received 1.0 mg/kg (i.c.) bolus with 1.25 +/- 0.04 mg/kg/h (i.v.) infusion (n = 8). Group III was given heparin 1.66 mg/kg (i.c.) bolus (n = 9). Aspiration of blood from the chest cavity revealed no significant difference between the three groups. Measurement of fibrin deposits in the pump line filter revealed higher amounts in the r-hirudin groups (P = 0.02). Decreases in platelets, fibrinogen and haematocrit due primarily to haemodilution were the same in each group. The bleeding time was less prolonged for r-hirudin than for heparin (p less than 0.001). No antagonist for r-hirudin was used; however, due to its short half-life, all coagulation parameters returned to baseline within 30 min after CPB. Since r-hirudin has no effect on platelets, is a poor immunogen, does not require a plasma cofactor, and may not require an antagonist, it may provide an alternative anticoagulant to heparin in CPB. Additional studies are, however, needed to optimize the dose and to evaluate other clinical aspects of r-hirudin.
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Affiliation(s)
- J M Walenga
- Department of Thoracic and Cardiovascular Surgery, Loyola University Medical Center, Maywood, Illinois 60153
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Fareed J, Walenga JM, Pifarre R, Hoppensteadt D, Koza M. Some objective considerations for the neutralization of the anticoagulant actions of recombinant hirudin. Haemostasis 1991; 21 Suppl 1:64-72. [PMID: 1894198 DOI: 10.1159/000216264] [Citation(s) in RCA: 4] [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] [Indexed: 12/29/2022]
Abstract
Recombinant hirudin (r-hirudin) is currently under development as an anticoagulant for use in surgery, therapeutic anticoagulation, disseminated intravascular coagulation and other pathologic states involving the generation of thrombin. Circulating levels of r-hirudin as an antithrombotic agent range from 2 to 20 micrograms/ml (0.1-1.0 mg/kg) as determined in an animal model of stasis thrombosis. In order to establish a relationship between the r-hirudin circulating level and bleeding, we utilized a rabbit ear blood loss model. r-Hirudin did not produce any loss of blood at dosages up to 20 micrograms/ml i.v. (1.0 mg/kg). When the circulating levels were maintained at 20 micrograms/ml for periods of up to 3 h, no increase in blood loss was observed. At 50 and 100 micrograms/ml initial circulating levels (2.5 and 5.0 mg/kg) a dose-dependent increase in the blood loss was observed which was equivalent to that observed with 1.25 and 2.5 mg/kg i.v. heparin. Such levels of r-hirudin are not expected in clinical usage. In contrast to heparin, the anticoagulant actions of r-hirudin were not neutralized by protamine sulfate, platelet factor 4, other polycationic agents and heparinase. In our studies, the blood loss induced by greater than 2.0 mg/kg i.v. dosages of r-hirudin in an animal model was neutralized by the administration of an activated prothrombin complex concentrate at 25 U/kg. In a similar experimental setting, r-factor VIIa was also partially effective. These studies suggest that r-hirudin anticoagulation may not require neutralization, since bleeding effects are not observed at effective antithrombotic dosages in individuals with normal hemostatic status.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J Fareed
- Department of Pathology, Loyola University Medical Center, Maywood, Ill
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Walenga JM, Hoppensteadt D, Koza M, Wallock M, Pifarre R, Fareed J. Laboratory assays for the evaluation of recombinant hirudin. Haemostasis 1991; 21 Suppl 1:49-63. [PMID: 1894197 DOI: 10.1159/000216263] [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] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Several laboratory methods are available to measure the anticoagulant activity of recombinant hirudin (r-hirudin), a potent thrombin inhibitor. These assays include clot-based, amidolytic, immunologic and physicochemical techniques. Although r-hirudin, like heparin, is an effective anticoagulant, the mechanism of action of the two agents is different. Thus it is not surprising that the global tests, such as the prothrombin time (PT), partial thromboplastin time (APTT) and the Heptest (Haemachem, Inc., St. Louis, Mo., USA), do not show adequate responses to r-hirudin. In the range of 0.5-10.0 microgram/ml, where full anticoagulation is achieved, as determined by animal models of thrombosis, these assays show little to no prolongation of the time to clot. In order to find a more suitable assay system, modifications of the above assays were evaluated. The diluted APTT and diluted Heptest showed linear concentration-dependent responses to lower levels of r-hirudin with an enhanced sensitivity than that of the classical assays. On the other hand, the diluted thrombin time was too sensitive. Whole-blood clotting assays, ACT and thrombelastograph, effectively measured r-hirudin levels up to 25 micrograms/ml. The amidolytic anti-factor IIa assay, specific for evaluating direct thrombin inhibition, was very effective particularly when modified to decrease the sample:thrombin ratio. This assay may be useful in quality control since it is biochemically defined, and reagents are easily standardized. The relevance of the results of the anti-IIa assay to clinical conditions, however, remains to be determined. Thrombin generation assays have limited value in monitoring the anticoagulant effect of r-hirudin since the effect of thrombin inhibition by r-hirudin on coagulation feedback mechanisms, and thus the effect on thrombin generation, appears to be minimal. Immunologic methods such as ELISA and RIA are under development, but they may only be useful for the direct quantitation of absolute levels of r-hirudin and not for monitoring the clinical anticoagulant action. Furthermore, these assays are only sensitive to sub-microgram/ml levels. Therefore, thrombin-based clotting and amidolytic assays may at present be the best choice for evaluating the functional, clinical antithrombotic effects of r-hirudin.
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Affiliation(s)
- J M Walenga
- Department of Thoracic Cardiovascular Surgery, Loyola University Medical Center, Maywood, Ill
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Brozak G, Helm M, DeRosa F, Perry CH, Koza M, Bhat R, Allen SJ. Thermal saturation of band transport in a superlattice. Phys Rev Lett 1990; 64:3163-3166. [PMID: 10041914 DOI: 10.1103/physrevlett.64.3163] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Duffield T, Bhat R, Koza M, DeRosa F, Rush KM, Allen SJ. Barrier-bound resonances in semiconductor superlattices in strong magnetic fields. Phys Rev Lett 1987; 59:2693-2696. [PMID: 10035624 DOI: 10.1103/physrevlett.59.2693] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Koza M. Hand washing urged. Tex Hosp 1986; 42:33. [PMID: 10279972] [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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Duffield T, Bhat R, Koza M, DeRosa F, Hwang DM, Grabbe P. Electron mass tunneling along the growth direction of (Al,Ga)As/GaAs semiconductor superlattices. Phys Rev Lett 1986; 56:2724-2727. [PMID: 10033074 DOI: 10.1103/physrevlett.56.2724] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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