55 results on '"B. Dionne"'
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2. Very Well-Covered Graphs with the Erd\H{o}s-Ko-Rado Property
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Jessica De Silva, Adam B. Dionne, Aidan Dunkelberg, and Pamela E. Harris
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General Mathematics ,Mathematics - Combinatorics ,05C35 - Abstract
A family of independent $r$-sets of a graph $G$ is an $r$-star if every set in the family contains some fixed vertex $v$. A graph is $r$-EKR if the maximum size of an intersecting family of independent $r$-sets is the size of an $r$-star. Holroyd and Talbot conjecture that a graph is $r$-EKR as long as $1\leq r\leq\frac{\mu(G)}{2}$, where $\mu(G)$ is the minimum size of a maximal independent set. It is suspected that the smallest counterexample to this conjecture is a well-covered graph. Here we consider the class of very well-covered graphs $G^*$ obtained by appending a single pendant edge to each vertex of $G$. We prove that the pendant complete graph $K_n^*$ is $r$-EKR when $n \geq 2r$ and strictly so when $n>2r$. Pendant path graphs $P_n^*$ are also explored and the vertex whose $r$-star is of maximum size is determined., Comment: 10 pages
- Published
- 2021
3. Verification and Validation of the PLTEMP/ANL Code for Thermal-Hydraulic Analysis of Experimental and Test Reactors
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N. Hanan, Arne P. Olson, E.E. Feldman, M. Kalimullah, and B. Dionne
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Thermal hydraulics ,Engineering drawing ,Mathematical model ,Computer science ,Volume (computing) ,Code (cryptography) ,Experimental data ,Specific model ,Reliability engineering ,Test (assessment) ,Verification and validation - Abstract
The document compiles in a single volume several verification and validation works done for the PLTEMP/ANL code during the years of its development and improvement. Some works that are available in the open literature are simply referenced at the outset, and are not included in the document. PLTEMP has been used in conversion safety analysis reports of several US and foreign research reactors that have been licensed and converted. A list of such reactors is given. Each chapter of the document deals with the verification or validation of a specific model. The model verification is usually done by comparing the code with hand calculation, Microsoft spreadsheet calculation, or Mathematica calculation. The model validation is done by comparing the code with experimental data or a more validated code like the RELAP5 code.
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- 2018
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4. DART Analysis of Irradiation Behavior of U-Mo/Al Dispersion Fuels
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B. Dionne, Gerard L. Hofman, J. Rest, Yeon Soo Kim, and Bei Ye
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Nuclear and High Energy Physics ,Dart ,Materials science ,020209 energy ,Nuclear engineering ,chemistry.chemical_element ,02 engineering and technology ,Condensed Matter Physics ,020303 mechanical engineering & transports ,0203 mechanical engineering ,Nuclear Energy and Engineering ,chemistry ,Aluminium ,Dispersion (optics) ,0202 electrical engineering, electronic engineering, information engineering ,Irradiation ,computer ,computer.programming_language - Abstract
DART (Dispersion Analysis Research Tool) is a computational code developed for integrated simulation of the irradiation behavior of aluminum dispersion fuels used in research reactors. The DART com...
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- 2015
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5. Verification of Historical System Transient Simulations for the RHF Research Reactor
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J. R. Licht, F. Thomas, B. Dionne, and A. Bergeron
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Materials science ,Nuclear engineering ,Research reactor ,Transient (oscillation) - Published
- 2017
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6. Supplemental Thermal-Hydraulic Transient Analyses of BR2 in Support of Conversion to LEU Fuel
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G. Van den Branden, E. Sikik, E. Koonen, J. R. Licht, and B. Dionne
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Engineering ,Natural circulation ,Nuclear reactor core ,Waste management ,business.industry ,Pressurizer ,Isolation valve ,Enriched uranium ,business ,Reactor pressure vessel ,Pressure vessel ,Coolant - Abstract
Belgian Reactor 2 (BR2) is a research and test reactor located in Mol, Belgium and is primarily used for radioisotope production and materials testing. The Materials Management and Minimization (M3) Reactor Conversion Program of the National Nuclear Security Administration (NNSA) is supporting the conversion of the BR2 reactor from Highly Enriched Uranium (HEU) fuel to Low Enriched Uranium (LEU) fuel. BR2 is a tank-in-pool type reactor cooled by light water and moderated by beryllium and light water (Figure 1). The reactor operates with downward flowing coolant at an inlet temperature of 35oC and an inlet pressure of 1.26 MPa. The reactor core is located inside a pressure vessel that contains 79 channels in a hyperboloid configuration. The core loading configuration is variable as each channel can contain a fuel assembly, a control or regulating rod, an experimental device, or a beryllium or aluminum plug. In case of a pressure loss accident, the primary system inside the pool is automatically opened to the pool by a pool connection valve (ABV4-1308) so that the reactor vessel can be kept full of coolant. Isolation valves on the inlet and outlet piping (ABV4-1304 and ABV4-1305, respectively) located at the pool wall automatically close tomore » stop leakage of the water from the reactor vessel. A bypass valve (ABV4-1301) located between the inlet and outlet piping is automatically opened to complete a natural circulation loop.« less
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- 2016
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7. Loss-of-Flow and Loss-of-Pressure Simulations of the BR2 Research Reactor with HEU and LEU Fuel
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B. Dionne, E. Koonen, J. R. Licht, E. Sikik, G. Van den Branden, and A. Bergeron
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Materials science ,Nuclear reactor core ,law ,Uranium-233 ,Nuclear engineering ,Nuclear reactor ,Fuel element failure ,MOX fuel ,Liquid fluoride thorium reactor ,Spent nuclear fuel ,law.invention ,Thorium fuel cycle - Published
- 2016
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8. Steady-State Thermal-Hydraulics Analyses for the Conversion of the BR2 Reactor to LEU
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B. Dionne, S. Kalcheva, A. Bergeron, G. Van den Branden, E. Koonen, J. R. Licht, and E. Sikik
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Thermal hydraulics ,Nuclear reactor core ,Critical heat flux ,law ,Chemistry ,Nuclear engineering ,Radiochemistry ,Steady state (chemistry) ,Neutron moderator ,Reactor pressure vessel ,Liquid fluoride thorium reactor ,Nucleate boiling ,law.invention - Published
- 2015
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9. RELAP5 Model Description and Validation for the BR2 Loss-of-Flow Experiments
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E. Sikik, J. R. Licht, G. Van den Branden, B. Dionne, and E. Koonen
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Engineering ,Model description ,Flow (mathematics) ,business.industry ,Calibration (statistics) ,Nuclear engineering ,Minor (linear algebra) ,business ,Simulation - Abstract
This paper presents a description of the RELAP5 model, the calibration method used to obtain the minor loss coefficients from the available hydraulic data and the LOFA simulation results compared to the 1963 experimental tests for HEU fuel.
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- 2015
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10. A User Guide to PARET/ANL
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M. Kalimullah, B. Dionne, Arne P. Olson, and A. Marin-Lafleche
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Engineering drawing ,Engineering ,business.industry ,business - Published
- 2015
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11. Neutronics Conversion Analyses of the Laue-Langevin Institute (ILL) High Flux Reactor (RHF)
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Y. Calzavara, A. Bergeron, and B. Dionne
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Neutron transport ,Engineering ,High flux ,Neutron transport theory ,Mathematical model ,business.industry ,Nuclear engineering ,Radiochemistry ,business ,Enriched uranium - Published
- 2014
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12. Summary of RELAP5 Assessments Performed in Relation to Conversion Analysis of Research Reactors
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B. Dionne, F. Dunn, E. Feldman, P. Garner, M. Kalimullah, and N. Hanan
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- 2014
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13. RHF RELAP5 model and preliminary loss-of-offsite-power simulation results for LEU conversion
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A. Bergeron, F. Thomas, B. Dionne, and J. R. Licht
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Engineering ,High flux ,business.industry ,Section (archaeology) ,Nuclear engineering ,Key (cryptography) ,Power simulation ,Status report ,business ,Simulation - Abstract
The purpose of this document is to describe the current state of the RELAP5 model for the Institut Laue-Langevin High Flux Reactor (RHF) located in Grenoble, France, and provide an update to the key information required to complete, for example, simulations for a loss of offsite power (LOOP) accident. A previous status report identified a list of 22 items to be resolved in order to complete the RELAP5 model. Most of these items have been resolved by ANL and the RHF team. Enough information was available to perform preliminary safety analyses and define the key items that are still required. Section 2 of this document describes the RELAP5 model of RHF. The final part of this section briefly summarizes previous model issues and resolutions. Section 3 of this document describes preliminary LOOP simulations for both HEU and LEU fuel at beginning of cycle conditions.
- Published
- 2014
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14. Reversal of OFI and CHF in Research Reactors Operating at 1 to 50 Bar. Version 1.0
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Arne P. Olson, E.E. Feldman, M. Kalimullah, B. Dionne, and J.E. Matos
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Physics ,Bar (music) ,business.industry ,Nuclear engineering ,Electrical engineering ,business - Published
- 2014
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15. Technical basis in support of the conversion of the University of Missouri Research Reactor (MURR) core from highly enriched to low-enriched uranium steady-state thermal- hydraulic analysis
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E. E. Feldman, B. Dionne, L. P. Foyto, M. Kallimullah, K. Kutikkad, J. C. McKibben, A. P. Olson, N. J. Peters, J. G. Stevens, J. A. Stillman, and null (University of Missouri-Columbia)
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Thermal hydraulics ,Engineering ,Steady state ,Waste management ,business.industry ,Core (manufacturing) ,Research reactor ,business ,Enriched uranium - Published
- 2013
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16. Steady-state thermal-hydraulics feasibility study for the conversion of the BR2 reactor to LEU. Revision 0
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B. Dionne, S. Kalcheva, E. Koonen, G. Van den Branden, John G. Stevens, and Arne P. Olson
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Thermal hydraulics ,Materials science ,Steady state (electronics) ,Nuclear engineering - Published
- 2011
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17. Estimation of steady-state and transcient power distributions for the RELAP analyses of the 1963 loss-of-flow and loss-of-pressure tests at BR2
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B. Dionne and C. P. Tzanos
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Engineering ,Steady state ,business.industry ,Nuclear engineering ,Flow (psychology) ,chemistry.chemical_element ,Uranium ,Cladding (fiber optics) ,Coolant ,Power (physics) ,Nuclear physics ,chemistry ,Thermocouple ,Transient (oscillation) ,business - Abstract
To support the safety analyses required for the conversion of the Belgian Reactor 2 (BR2) from highly-enriched uranium (HEU) to low-enriched uranium (LEU) fuel, the simulation of a number of loss-of-flow tests, with or without loss of pressure, has been undertaken. These tests were performed at BR2 in 1963 and used instrumented fuel assemblies (FAs) with thermocouples (TC) imbedded in the cladding as well as probes to measure the FAs power on the basis of their coolant temperature rise. The availability of experimental data for these tests offers an opportunity to better establish the credibility of the RELAP5-3D model and methodology used in the conversion analysis. In order to support the HEU to LEU conversion safety analyses of the BR2 reactor, RELAP simulations of a number of loss-of-flow/loss-of-pressure tests have been undertaken. Preliminary analyses showed that the conservative power distributions used historically in the BR2 RELAP model resulted in a significant overestimation of the peak cladding temperature during the transient. Therefore, it was concluded that better estimates of the steady-state and decay power distributions were needed to accurately predict the cladding temperatures measured during the tests and establish the credibility of the RELAP model and methodology. The new approach ('bestmore » estimate' methodology) uses the MCNP5, ORIGEN-2 and BERYL codes to obtain steady-state and decay power distributions for the BR2 core during the tests A/400/1, C/600/3 and F/400/1. This methodology can be easily extended to simulate any BR2 core configuration. Comparisons with measured peak cladding temperatures showed a much better agreement when power distributions obtained with the new methodology are used.« less
- Published
- 2011
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18. Computational fluid dynamics analyses of lateral heat conduction, coolant azimuthal mixing and heat transfer predictions in a BR2 fuel assembly geometry
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C. P. Tzanos and B. Dionne
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Thermal hydraulics ,Thermal conductivity ,Heat flux ,Chemistry ,Heat transfer ,Thermodynamics ,Fluid mechanics ,Heat transfer coefficient ,Mechanics ,Thermal conduction ,Coolant - Abstract
To support the analyses related to the conversion of the BR2 core from highly-enriched (HEU) to low-enriched (LEU) fuel, the thermal-hydraulics codes PLTEMP and RELAP-3D are used to evaluate the safety margins during steady-state operation (PLTEMP), as well as after a loss-of-flow, loss-of-pressure, or a loss of coolant event (RELAP). In the 1-D PLTEMP and RELAP simulations, conduction in the azimuthal and axial directions is not accounted. The very good thermal conductivity of the cladding and the fuel meat and significant temperature gradients in the lateral directions (axial and azimuthal directions) could lead to a heat flux distribution that is significantly different than the power distribution. To evaluate the significance of the lateral heat conduction, 3-D computational fluid dynamics (CFD) simulations, using the CFD code STAR-CD, were performed. Safety margin calculations are typically performed for a hot stripe, i.e., an azimuthal region of the fuel plates/coolant channel containing the power peak. In a RELAP model, for example, a channel between two plates could be divided into a number of RELAP channels (stripes) in the azimuthal direction. In a PLTEMP model, the effect of azimuthal power peaking could be taken into account by using engineering factors. However, if the thermal mixingmore » in the azimuthal direction of a coolant channel is significant, a stripping approach could be overly conservative by not taking into account this mixing. STAR-CD simulations were also performed to study the thermal mixing in the coolant. Section II of this document presents the results of the analyses of the lateral heat conduction and azimuthal thermal mixing in a coolant channel. Finally, PLTEMP and RELAP simulations rely on the use of correlations to determine heat transfer coefficients. Previous analyses showed that the Dittus-Boelter correlation gives significantly more conservative (lower) predictions than the correlations of Sieder-Tate and Petukhov. STAR-CD 3-D simulations were performed to compare heat transfer predictions from CFD and the correlations. Section III of this document presents the results of this analysis.« less
- Published
- 2011
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19. Thermal properties for the thermal-hydraulics analyses of the BR2 maximum nominal heat flux
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B. Dionne, Y. S. Kim, and G. L. Hofman
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- 2011
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20. A persistent store for large shared knowledge bases
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S. Lanka, B. Dionne, R. Weida, and Eric Mays
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Structure (mathematical logic) ,Knowledge representation and reasoning ,Database ,business.industry ,Computer science ,Knowledge engineering ,Base (topology) ,computer.software_genre ,Computer Science Applications ,Shared resource ,Consistency (database systems) ,Knowledge-based systems ,Computational Theory and Mathematics ,Knowledge base ,Scalability ,Stable storage ,User interface ,Cluster analysis ,business ,computer ,Information Systems - Abstract
Techniques for managing problems associated with the scalability of large knowledge-based systems are presented. The discussion is based on experience in building a large knowledge-based system and on perceptions regarding future technological requirements to support ongoing development. Achieving persistence for knowledge bases (KBs) is investigated. Persistence refers to storing a knowledge base on a stable storage medium such as a magnetic disk. A knowledge base management system (KBMS) in which a large KB is concurrently developed by a team of collaborating knowledge engineers is proposed. At the heart of the KBMS is a version store, which is a persistent storage structure for a KB. To support the concurrent collaborative work, the version store maintains multiple versions of a KB such that a knowledge engineer can access and modify any version. Retrieval and updating operations have been defined on the version store to efficiently access and modify any version. Objects in a version store are clustered to support efficient access of an entire version of the KB or subparts of it. The retrieval algorithm has been validated through simulation. A prototype of the version store has been implemented and is being integrated into the user interface. >
- Published
- 2002
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21. Extrication challenges. Cement mixer entrapment
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A J, Heightman and B, Dionne
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Male ,Outcome Assessment, Health Care ,Rescue Work ,Accidents, Occupational ,Humans ,Illinois ,Emergency Treatment ,Physical Examination - Published
- 2001
22. Deriving cleanup guidelines for radionuclides at Brookhaven National Laboratory
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A.F. Meinhold, P.D. Moskowitz, B. Dionne, and S.C. Morris
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Remedial action ,Radionuclide ,Groundwater contamination ,Waste management ,business.industry ,Environmental engineering ,Environmental science ,Environmental restoration ,Radiation protection ,National laboratory ,business ,complex mixtures ,Superfund site - Abstract
Past activities at Brookhaven National Laboratory (BNL) resulted in soil and groundwater contamination. As a result, BNL was designated a Superfund site under the Comprehensive Environmental Response Compensation and Liability Act (CERCLA). BNL`s Office of Environmental Restoration (OER) is overseeing environmental restoration activities at the Laboratory. With the exception of radium, there are no regulations or guidelines to establish cleanup guidelines for radionuclides in soils at BNL. BNL must derive radionuclide soil cleanup guidelines for a number of Operable Units (OUs) and Areas of Concern (AOCs). These guidelines are required by DOE under a proposed regulation for radiation protection of public health and the environment as well as to satisfy the requirements of CERCLA. The objective of this report is to propose a standard approach to deriving risk-based cleanup guidelines for radionuclides in soil at BNL. Implementation of the approach is briefly discussed.
- Published
- 1997
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23. The Geochemistry of Oceanic Crust at the Onset of Rifting in the Indian Ocean
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J.N. Ludden and B. Dionne
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- 1992
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24. Occupational dose reduction at nuclear power plants: Annotated bibliography of selected readings in radiation protection and ALARA
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T Khan, H Tan, J Baum, and B Dionne
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- 1990
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25. WE-E-ValA-06: A Real-Time MRI Guided External Beam Radiotherapy Delivery System
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Jeffrey R. Fitzsimmons, Daniel A. Low, Sasa Mutic, B Dionne, G.E. Sjoden, A Haghigat, J.R. Palta, Jonathan G. Li, H Romeijn, and James F. Dempsey
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medicine.medical_specialty ,medicine.diagnostic_test ,Computer science ,medicine.medical_treatment ,Radiotherapy unit ,Isocenter ,Soft tissue ,Magnetic resonance imaging ,General Medicine ,Real-time MRI ,Intensity-modulated radiation therapy ,Radiation therapy ,Organ Motion ,medicine ,Dosimetry ,Medical physics ,External beam radiotherapy - Abstract
Purpose: We present feasibility studies in support of a real‐time MRI guided external beam radiotherapy delivery system currently under commercial development. Method and Materials: The system, (ViewRay Inc., Renaissance™), combines a low field open MRI scanner and a multi‐headed 60Co γ‐ray IMRT unit equipped with multi‐leaf collimators. It is designed so that the center of the field of view of the MRI and the isocenter of the radiotherapy unit coincide. The inherent compatibility of the units allows for the acquisition of fast cine MRI simultaneous to radiotherapy delivery to assess intra‐fraction organ motion. Computational feasibility studies were performed to investigate: the compatibility of the MRI and the 60Co γ‐ray IMRT unit; the impact of the MRImagnetic field on the dosimetry; and the feasibility of performing accurate heterogeneity dose computations with MRI data. Results: The 60Co γ‐ray IMRT unit was found not to significantly impact the operation of the MRI; the γ‐ray IMRT unit is capable of producing high quality IMRT treatment plans; the MRImagnetic field eliminates contamination electrons and does not significantly perturb the dose distribution in lung, soft tissue, and bone; and accurate heterogeneity dose computations are possible employing only MRI data. Conclusion: Performing IMRT allows for the seamless integration with, and simultaneous operation of, an open MRI unit. Conflict of Interest: Research sponsored by ViewRay, Inc., Gainesville, Florida USA.
- Published
- 2006
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26. [From cell to society]
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B, Dionne-Nolin
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Philosophy ,Human Development ,Brain ,Humans ,Biology ,Personality - Published
- 1985
27. Implementation of a Pharmacist-Driven Vancomycin Area Under the Concentration-Time Curve Monitoring Program Using Bayesian Modeling in Outpatient Parenteral Antimicrobial Therapy.
- Author
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Gillett E, Aleissa MM, Pearson JC, Solomon DA, Kubiak DW, Dionne B, Edrees HH, Okenla A, and Chan BT
- Abstract
Background: Current vancomycin monitoring guidelines recommend monitoring 24-hour area under the concentration-time curve (AUC) to minimum inhibitory concentration ratios for patients with serious methicillin-resistant Staphylococcus aureus infections. However, there are sparse data on the safety, feasibility, and efficacy of vancomycin AUC monitoring for outpatients. Traditional AUC pharmacokinetic calculations require 2 concentrations, while bayesian software allows for single-concentration AUC estimations., Methods: We conducted a single-center, quasi-experimental, interrupted time series study of patients enrolled in the outpatient parenteral antimicrobial therapy program at our institution for vancomycin management. Our institution implemented a pharmacist-driven vancomycin AUC monitoring program from September 2019 to February 2020, and again from September 2022 to March 2023. Patients enrolled underwent vancomycin monitoring using an AUC goal of 400-600 mg⋅h/L, estimated through bayesian modeling. Patients enrolled in the outpatient parenteral antimicrobial therapy program from July 2021 through August 2022 for trough-based monitoring were used for comparison. The primary outcome was nephrotoxicity incidence, defined as a serum creatinine increase by ≥0.5 mg/dL or ≥50% during outpatient vancomycin therapy., Results: We enrolled 63 patients in the AUC group and 60 patients in the trough-based group. Nephrotoxicity was significantly lower in the AUC cohort (6.3% vs 23.3%; P = .01). The number of unusable vancomycin concentrations was also significantly lower in the AUC cohort (0% vs 6%; P < .01). There was no difference in composite 90-day all-cause mortality or readmission (33.3% vs 38.3%; P = .56)., Conclusions: Following implementation of a pharmacist-driven AUC monitoring program, patients were less likely to develop nephrotoxicity during outpatient vancomycin therapy., Competing Interests: Potential conflicts of interest. All authors: No reported conflicts., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)
- Published
- 2024
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28. Facility-level antibiotic prescribing rates and the use of antibiotics among nursing home residents.
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Vo QT, Noubary F, Dionne B, Doron S, Koethe B, and Briesacher BA
- Abstract
Background: The high frequency of antibiotic use in US nursing homes is a public health concern. Facility-level prescribing patterns may provide a measure for antibiotic stewardship targeting., Methods: An analysis of 2018-2019 data from linked files from the Centers for Medicaid and Medicare was conducted. Multilevel generalized linear models were used to calculate odds ratios for antibiotic receipt for calendar year 2019 using the 2018 facility prescribing rate., Results: In 2019, 186,274 (19%) residents were prescribed an antibiotic. The most frequently prescribed class of antibiotics was cephalosporins (26%), and the average duration of antibiotic use was 9 days. Residents who were dually eligible for Medicare and Medicaid had 37% increased odds of antibiotic receipt (all adjusted odds ratio (aOR): 1.37, 95% confidence interval [CI]: 1.35, 1.39). The 2018 facility prescribing rate was associated with 14% increased odds of antibiotic receipt in 2019 in NHs in the medium (11.9%-20.2%) prescribing category (all aOR: 1.14, 95% CI: 1.11, 1.17) and 36% increased odds of antibiotic receipt in NHs in the high (> 20.3%) prescribing category (all aOR: 1.36, 95% CI: 1.32, 1.40) when compared with the lowest (0%-11.8%) prescribing category., Conclusions: Antibiotic stewardship strategies should target nursing homes with high antibiotic prescribing rates and high populations of dually eligible patients to improve care in this population., (Copyright © 2024 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.)
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- 2024
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29. Real-World Dalbavancin Use for Serious Gram-Positive Infections: Comparing Outcomes Between People Who Use and Do Not Use Drugs.
- Author
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Zambrano S, Paras ML, Suzuki J, Pearson JC, Dionne B, Schrager H, Mallada J, Szpak V, Fairbank-Haynes K, Kalter M, Prostko S, and Solomon DA
- Abstract
Background: Dalbavancin has been used off-label to treat invasive bacterial infections in vulnerable populations like people who use drugs (PWUD) because of its broad gram-positive coverage and unique pharmacological properties. This retrospective, multisite study examined clinical outcomes at 90 days in PWUD versus non-PWUD after secondary treatment with dalbavancin for bacteremia, endocarditis, osteomyelitis, septic arthritis, and epidural abscesses., Methods: Patients at 3 teaching hospitals who received dalbavancin for an invasive infection between March 2016 and May 2022 were included. Characteristics of PWUD and non-PWUD, infection highlights, hospital stay and treatment, and outcomes were compared using χ
2 for categorical variables, t test for continuous variables, and nonparametric tests where appropriate., Results: There were a total of 176 patients; 78 were PWUD and 98 were non-PWUD. PWUD were more likely to have a patient-directed discharge (26.9% vs 3.1%; P < .001) and be lost to follow-up (20.5% vs 7.14%; P < .01). Assuming loss to follow-up did not achieve clinical cure, 73.1% of PWUD and 74.5% of non-PWUD achieved clinical cure at 90 days ( P = .08)., Conclusions: Dalbavancin was an effective treatment option for invasive gram-positive infections in our patient population. Despite higher rates of patient-directed discharge and loss to follow-up, PWUD had similar rates of clinical cure at 90 days compared to non-PWUD., Competing Interests: Potential conflicts of interest. All authors: No reported conflicts., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)- Published
- 2024
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30. Dalbavancin Sequential Therapy for Gram-Positive Bloodstream Infection: A Multicenter Observational Study.
- Author
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Rebold N, Alosaimy S, Pearson JC, Dionne B, Taqi A, Lagnf A, Lucas K, Biagi M, Lombardo N, Eudy J, Anderson DT, Mahoney MV, Kufel WD, D'Antonio JA, Jones BM, Frens JJ, Baumeister T, Geriak M, Sakoulas G, Farmakiotis D, Delaportas D, Larew J, Veve MP, and Rybak MJ
- Abstract
Introduction: Long-acting lipoglycopeptides such as dalbavancin may have utility in patients with Gram-positive bloodstream infections (BSI), particularly in those with barriers to discharge or who require prolonged parenteral antibiotic courses. A retrospective cohort study was performed to provide further multicenter real-world evidence on dalbavancin use as a sequential therapy for Gram-positive BSI., Methods: One hundred fifteen patients received dalbavancin with Gram-positive BSI, defined as any positive blood culture or diagnosed with infective endocarditis, from 13 centers geographically spread across the United States between July 2015 and July 2021., Results: Patients had a mean (SD) age of 48.5 (17.5) years, the majority were male (54%), with many who injected drugs (40%). The most common infection sources (non-exclusive) were primary BSI (89%), skin and soft tissue infection (SSTI) (25%), infective endocarditis (19%), and bone and joint infection (17%). Staphylococcus aureus accounted for 72% of index cultures, coagulase-negative Staphylococcus accounted for 18%, and Streptococcus species in 16%. Dalbavancin started a median (Q
1 -Q3 ) of 10 (6-19) days after index culture collection. The most common regimen administered was dalbavancin 1500 mg as one dose for 50% of cases. The primary outcome of composite clinical failure occurred at 12.2%, with 90-day mortality at 7.0% and 90-day BSI recurrence at 3.5%., Conclusions: Dalbavancin may serve as a useful tool in facilitating hospital discharge in patients with Gram-positive BSI. Randomized controlled trials are anticipated to validate dalbavancin as a surrogate to current treatment standards., (© 2024. The Author(s).)- Published
- 2024
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31. Evaluation of an Opt-Out Protocol for Antibiotic De-Escalation in Patients With Suspected Sepsis: A Multicenter, Randomized, Controlled Trial.
- Author
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Moehring RW, Yarrington ME, Warren BG, Lokhnygina Y, Atkinson E, Bankston A, Collucio J, David MZ, Davis AE, Davis J, Dionne B, Dyer AP, Jones TM, Klompas M, Kubiak DW, Marsalis J, Omorogbe J, Orajaka P, Parish A, Parker T, Pearson JC, Pearson T, Sarubbi C, Shaw C, Spivey J, Wolf R, Wrenn RH, Dodds Ashley ES, and Anderson DJ
- Subjects
- Adult, Humans, Randomized Controlled Trials as Topic, Multicenter Studies as Topic, Anti-Bacterial Agents adverse effects, Sepsis drug therapy, Sepsis microbiology
- Abstract
Background: Sepsis guidelines recommend daily review to de-escalate or stop antibiotics in appropriate patients. This randomized, controlled trial evaluated an opt-out protocol to decrease unnecessary antibiotics in patients with suspected sepsis., Methods: We evaluated non-intensive care adults on broad-spectrum antibiotics despite negative blood cultures at 10 US hospitals from September 2018 through May 2020. A 23-item safety check excluded patients with ongoing signs of systemic infection, concerning or inadequate microbiologic data, or high-risk conditions. Eligible patients were randomized to the opt-out protocol vs usual care. Primary outcome was post-enrollment antibacterial days of therapy (DOT). Clinicians caring for intervention patients were contacted to encourage antibiotic discontinuation using opt-out language. If continued, clinicians discussed the rationale for continuing antibiotics and de-escalation plans. To evaluate those with zero post-enrollment DOT, hurdle models provided 2 measures: odds ratio of antibiotic continuation and ratio of mean DOT among those who continued antibiotics., Results: Among 9606 patients screened, 767 (8%) were enrolled. Intervention patients had 32% lower odds of antibiotic continuation (79% vs 84%; odds ratio, 0.68; 95% confidence interval [CI], .47-.98). DOT among those who continued antibiotics were similar (ratio of means, 1.06; 95% CI, .88-1.26). Fewer intervention patients were exposed to extended-spectrum antibiotics (36% vs 44%). Common reasons for continuing antibiotics were treatment of localized infection (76%) and belief that stopping antibiotics was unsafe (31%). Thirty-day safety events were similar., Conclusions: An antibiotic opt-out protocol that targeted patients with suspected sepsis resulted in more antibiotic discontinuations, similar DOT when antibiotics were continued, and no evidence of harm., Clinical Trials Registration: NCT03517007., Competing Interests: Potential conflicts of interest. E. D. A. reports grants or contracts from the University of Maryland (paid to author), University of Chicago (paid to author), CDC Prevention Epicenter Program (paid to institution), Oxford University Clinical Research Unit (paid to author), CDC (paid to institution), and DASON Member Hospital Contracts (paid to institution); royalties or licenses from UpToDate (paid to author); consulting fees from the American College of Clinical Pharmacy (paid to author), Hospital Association of New York State (paid to author), Sarah Moreland Russel Consulting (paid to author), and HealthTrackRX (paid to author); and support for attending meetings and/or travel from the American Society of Microbiology (paid to author), Pew Charitable Trusts (paid to author), and Oxford University Clinical Research Unit (paid to institution). A. E. D. reports payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational events from Merck & Co (paid to author). M. Z. D. reports grants or contracts from the National Institutes of Health, GSK, Johnson & Johnson, and Contrafect (paid to institution); support for attending meetings and/or travel from GSK; and participation on a data and safety monitoring board or advisory board for GSK (paid to author). D. J. A. reports grants or contracts from Agency for Healthcare Research and Quality (to institution), royalties or licenses from UpToDate Online (paid to author), and other financial or nonfinancial interests from Infection Control Education for Major Sports, LLC (owner). M. K. reports grants or contracts from Agency for Healthcare Research and Quality (paid to institution) and the Massachusetts Department of Public Health (paid to institution) and royalties or licenses from UpToDate (paid to author). R. W. M. reports grants or contracts from the CDC (paid to institution) and the Agency for Healthcare Research and Quality (paid to institution), royalties or licenses from UpToDate, Inc. (paid to author), speaker honoraria for the North Carolina Statewide Program for Infection Control and Epidemiology (paid to author), support for attending meetings and/or travel from the Society for Healthcare Epidemiology of America, and is on the Society for Healthcare Epidemiology of America Board of Trustees. A. P. reports grants from Clinical and Translational Science Award (to Biostatistics, Epidemiology, and Research Design Core, within the Biostatistics and Bioinformatics Department at Duke University). J. C. P. reports serving on the advisory boards for Shionogi, Inc, and Gilead Sciences, Inc. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
- Published
- 2023
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32. Vancomycin Area under the Concentration-Time Curve Estimation Using Bayesian Modeling versus First-Order Pharmacokinetic Equations: A Quasi-Experimental Study.
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Alsowaida YS, Kubiak DW, Dionne B, Kovacevic MP, and Pearson JC
- Abstract
Aim: To evaluate the efficiency of Bayesian modeling software and first-order pharmacokinetic (PK) equations to calculate vancomycin area under the concentration-time curve (AUC) estimations., Methods: Unblinded, crossover, quasi-experimental study at a tertiary care hospital for patients receiving intravenous vancomycin. Vancomycin AUC monitoring was compared using Bayesian modeling software or first-order PK equations. The primary endpoint was the time taken to estimate the AUC and determine regimen adjustments. Secondary endpoints included the percentage of vancomycin concentrations usable for AUC calculations and acute kidney injury (AKI)., Results: Of the 124 patients screened, 34 patients had usable vancomycin concentrations that led to 44 AUC estimations. Without electronic health record (EHR) integration, the time from assessment to intervention in the Bayesian modeling platform was a median of 9.3 min (quartiles Q
1 -Q3 7.8-12.4) compared to 6.8 min (Q1 -Q3 4.8-8.0) in the PK equations group ( p = 0.004). With simulated Bayesian software integration into the EHR, however, the median time was 3.8 min (Q1 -Q3 2.3-6.9, p = 0.019). Vancomycin concentrations were usable in 88.2% in the Bayesian group compared to 48.3% in the PK equation group and there were no cases of AKI., Conclusion: Without EHR integration, Bayesian software was more time-consuming to assess vancomycin dosing than PK equations. With simulated integration, however, Bayesian software was more time efficient. In addition, vancomycin concentrations were more likely to be usable for calculations in the Bayesian group.- Published
- 2022
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33. Which pharmacists are performing antimicrobial stewardship: A national survey and a call for collaborative efforts.
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Dionne B, Wagner JL, Chastain DB, Rosenthal M, Mahoney MV, and Bland CM
- Abstract
Objectives: To determine how pharmacists with formal antimicrobial stewardship program (ASP) responsibilities prioritize their time and pharmacists without formal antimicrobial stewardship program responsibilities contribute to ASP activities., Design: A nationwide survey., Respondents: Members of the American College of Clinical Pharmacy who subscribe to the following practice and research network e-mail listservs: infectious diseases, adult medicine, cardiology, critical care, hematology-oncology, immunology and transplantation, and pediatrics., Methods: A survey was distributed via listservs. Respondents were asked about their personal and institutional demographics and ASP activities., Results: In total, 245 pharmacists responded: 135 pharmacists with formal antimicrobial stewardship program responsibilities; 110 pharmacists without formal antimicrobial stewardship program responsibilities. Although most respondents had completed a general pharmacy residency (85%), only 20% had completed an infectious diseases (ID) specialty residency. Among pharmacists with formal antimicrobial stewardship program responsibilities, one-third had no formal training or certification in ID or ASP. Pharmacists without formal antimicrobial stewardship program responsibilities spent ∼12.5% of their time per week on ASP activities, whereas pharmacists with formal antimicrobial stewardship program responsibilities spent 28% of their time performing non-ASP activities. Pharmacists with formal antimicrobial stewardship program responsibilities were more likely than pharmacists without formal antimicrobial stewardship program responsibilities to perform antibiotic guideline development ( P < .001), antibiotic-related education ( P = .002), and direct notification of rapid diagnostic results ( P = .018). Pharmacists with formal antimicrobial stewardship program responsibilities without formal ID training or certification spent less time on ASP activities and were more likely to perform lower-level interventions., Conclusions: Many ASP activities are being performed by pharmacists without formal ID training. To ensure the future success of ASPs, pharmacists with formal antimicrobial stewardship program responsibilities should have adequate training to meet more advanced metrics, and more pharmacists without formal antimicrobial stewardship program responsibilities should be included in basic interventions., (© The Author(s) 2022.)
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- 2022
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34. Probable Immortal Time Bias in Comparison of Daptomycin and Vancomycin for Methicillin-resistant Staphylococcus Aureus Bloodstream Infections.
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Dionne B and Lee TC
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- Humans, Vancomycin therapeutic use, Bacteremia drug therapy, Daptomycin therapeutic use, Methicillin-Resistant Staphylococcus aureus, Staphylococcal Infections drug therapy
- Published
- 2021
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35. Treatment of Chronic Granulomatous Disease-Related Pulmonary Aspergillus Infection in Late Pregnancy.
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Johnson JA, Pearson JC, Kubiak DW, Dionne B, Little SE, and Wesemann DR
- Abstract
Chronic granulomatous disease (CGD) is a primary immunodeficiency syndrome that results in increased risk for bacterial and fungal infections, as well as inflammatory/autoimmune complications. While CGD historically has been associated with early death in childhood, the life expectancy and morbidity of patients with CGD have greatly improved. Many patients with CGD now survive well into adulthood, and data on adult cohorts of patients with CGD have been published. However, reports of pregnancy management, complications, and outcomes for patients with CGD are sparse. In addition, management of invasive fungal infections, including use of newer triazole antifungals, during pregnancy has not been well described. We report a case of fungal lung infection in a pregnant woman with CGD, diagnosed during her second trimester, which was treated with multiple antifungal agents, including more than 12 weeks of isavuconazole therapy, resulting in resolution of infection and delivery of a healthy newborn at term., (© The Author(s) 2020. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)
- Published
- 2020
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36. Omadacycline for the Treatment of Mycobacterium abscessus Disease: A Case Series.
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Pearson JC, Dionne B, Richterman A, Vidal SJ, Weiss Z, Velásquez GE, Marty FM, Sax PE, and Yawetz S
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Background: Omadacycline is an aminomethylcycline antimicrobial approved by the US Food and Drug Administration in 2018 for community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections. It has in vitro activity against nontuberculous mycobacteria, including Mycobacterium abscessus complex, but clinical data for this indication are lacking., Methods: Omadacycline use was reviewed at an 804-bed academic medical center. Patients were included if they received omadacycline for culture-proven M abscessus disease in 2019., Results: Four patients received omadacycline for the treatment of culture-positive M abscessus disease in 2019. Two patients had cutaneous disease, 1 had pulmonary disease, and 1 had osteomyelitis and bacteremia. The patients received omadacycline for a median duration of 166 days (range, 104-227) along with a combination of other antimicrobial agents. Omadacycline-containing regimens were associated with a clinical cure in 3 of 4 patients, with 1 patient improving on ongoing treatment. Omadacycline's tolerability was acceptable for patients with M abscessus disease, with 1 patient discontinuing therapy in month 6 due to nausea., Conclusions: Omadacycline is a novel oral option for the treatment of M abscessus disease, for which safe and effective options are needed. Although this case series is promising, further data are required to determine omadacycline's definitive role in the treatment of M abscessus disease., (© The Author(s) 2020. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)
- Published
- 2020
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37. Key Principles of Antiretroviral Pharmacology.
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Dionne B
- Subjects
- Anti-Retroviral Agents adverse effects, Anti-Retroviral Agents pharmacokinetics, Anti-Retroviral Agents pharmacology, Antiretroviral Therapy, Highly Active adverse effects, Drug Interactions, Drug-Related Side Effects and Adverse Reactions, Humans, Anti-Retroviral Agents administration & dosage, Antiretroviral Therapy, Highly Active methods, HIV Infections drug therapy
- Abstract
Antiretroviral therapy has advanced significantly since zidovudine was first approved. Although 31 antiretrovirals have been approved by the FDA, only about half of those are commonly used. Newer, more tolerable agents have made human immunodeficiency virus into a chronic condition, which can be managed with medication. The most common antiretroviral regimens consist of 2 nucleoside reverse transcriptase inhibitors plus a third agent, often an integrase inhibitor because of better tolerability and fewer drug interactions than other regimens. Understanding the dosage forms, adverse effects, and drug interactions of antiretrovirals allow clinicians to choose the most appropriate regimen for their patient. New developments, such as branded generic regimens and long-acting intramuscular injections, may play a larger role in the future., (Copyright © 2019 Elsevier Inc. All rights reserved.)
- Published
- 2019
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38. Interplay between Rapid Diagnostic Tests and Antimicrobial Stewardship Programs among Patients with Bloodstream and Other Severe Infections.
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Beganovic M, McCreary EK, Mahoney MV, Dionne B, Green DA, and Timbrook TT
- Subjects
- Anti-Infective Agents pharmacology, Anti-Infective Agents therapeutic use, Bacteremia drug therapy, Bacteremia microbiology, Bacteria genetics, Bacteria isolation & purification, Central Nervous System Infections blood, Central Nervous System Infections drug therapy, Central Nervous System Infections microbiology, Drug Resistance, Bacterial genetics, Drug Resistance, Fungal genetics, Fungemia drug therapy, Fungemia microbiology, Fungi genetics, Fungi isolation & purification, Gastroenteritis blood, Gastroenteritis drug therapy, Gastroenteritis microbiology, Genotyping Techniques instrumentation, Genotyping Techniques methods, Humans, Microbial Sensitivity Tests instrumentation, Microbial Sensitivity Tests methods, Respiratory Tract Infections blood, Respiratory Tract Infections drug therapy, Respiratory Tract Infections microbiology, Severity of Illness Index, Time Factors, Time-to-Treatment, Antimicrobial Stewardship methods, Bacteremia diagnosis, Central Nervous System Infections diagnosis, Fungemia diagnosis, Gastroenteritis diagnosis, Reagent Kits, Diagnostic, Respiratory Tract Infections diagnosis
- Abstract
Background: Antimicrobial stewardship programs (ASPs) aim to provide optimal antimicrobial therapy to patients quickly to improve the likelihood of overcoming infection while reducing the risk of adverse effects. Rapid diagnostic tests (RDTs) for infectious diseases have become an integral tool for ASPs to achieve these aims., Content: This review explored the demonstrated clinical value of longer-standing technologies and implications of newer RDTs from an antimicrobial stewardship perspective. Based on available literature, the focus was on the use of RDTs in bloodstream infections (BSIs), particularly those that perform organism identification and genotypic resistance detection, phenotypic susceptibility testing, and direct specimen testing. Clinical implications of rapid testing among respiratory, central nervous system, and gastrointestinal infections are also reviewed., Summary: Coupling RDTs with ASPs facilitates the appropriate and timely use of test results, translating into improved patient outcomes through optimization of antimicrobial use. These benefits are best demonstrated in the use of RDT in BSIs. Rapid phenotypic susceptibility testing offers the potential for early pharmacokinetic/pharmacodynamic optimization, and direct specimen testing on blood may allow ASPs to initiate appropriate therapy and/or tailor empiric therapy even sooner than other RDTs. RDTs for respiratory, central nervous system, and gastrointestinal illnesses have also shown significant promise, although more outcome studies are needed to evaluate their full impact., (© 2018 American Association for Clinical Chemistry.)
- Published
- 2019
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39. The Asplenic Patient: Post-Insult Immunocompetence, Infection, and Vaccination.
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Dionne B, Dehority W, Brett M, and Howdieshell TR
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- Antibiotic Prophylaxis, Humans, Immunity, Active, Perioperative Care, Immunocompetence, Postoperative Complications, Practice Guidelines as Topic, Splenectomy, Vaccination
- Abstract
Background: Splenic injury can occur through multiple mechanisms and may result in various degrees of residual immunocompetence. Functionally or anatomically asplenic patients are at higher risk for infection, particularly with encapsulated bacteria. Vaccination is recommended to prevent infection with these organisms; however, the recommendations are routinely updated, and vaccine selection and timing are complex., Methods: Review of the pertinent English-language literature, including the recommendations of the U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices., Results: Overwhelming post-splenectomy infection is associated with high morbidity and mortality rates. Patients requiring splenectomy for trauma-related injury appear to be at lower risk for infection than those undergoing splenectomy for a hematologic or oncologic indication. Initial vaccination is dependent on immunization history but generally should consist of the 13-valent pneumococcal conjugate, quadrivalent meningococcal conjugate, meningococcal serogroup B, and Haemophilus influenzae serotype b (Hib) vaccines. Antimicrobial prophylaxis for certain asplenic patients, such as children under the age of five y, may be indicated., Conclusion: Immunization remains a key measure to prevent overwhelming post-splenectomy infection. Consideration of new recommendations and indications, possible interactions, and timing remains important to including optimal response to the vaccines.
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- 2017
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40. A low redox potential affects monoclonal antibody assembly and glycosylation in cell culture.
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Dionne B, Mishra N, and Butler M
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- Animals, Cell Line, Cell Proliferation drug effects, Glycosylation drug effects, Mice, Oxidation-Reduction drug effects, Antibodies, Monoclonal chemistry, Antibodies, Monoclonal metabolism, Cell Culture Techniques methods, Dithiothreitol pharmacology
- Abstract
Glycosylation and intracellular assembly of monoclonal antibodies (MAbs) is important for glycan profile consistency. To better understand how these factors may be influenced by a lower redox potential, an IgG1-producing NS0 cell line was grown in the presence of varying concentrations of dithiothreitol (DTT). Cultures were monitored for growth and culture redox potential (CRP) with glycan heterogeneity determined using a HILIC-HPLC method. Macroheterogeneity was unchanged in all conditions whereas the Galactosylation Index (GI) decreased by as much as 50% in cultures with lower CRP or higher dithiothreitol levels. This shift in GI is reflected in more agalactosylated and asialylated species being produced. The MAb assembly pathway was determined using radioactive isotope
35 S incorporated into nascent IgG1 molecules. The assembly pathway for this IgG1 was shown to progress via HC→HC2 →HC2 LC→HC2 LC2 in all conditions tested and autoradiographs highlighted that the ratio of heavy chain dimer to heavy chain monomer increased over time with increasing DTT concentrations. This increase and correspondingly lower GI values may be due to disruption of the disulfide bonds at higher levels of assembly. A change in the assembly pathway may alter the final IgG glycan pattern and lead to control mechanisms that influence glycan profiles of MAbs., (Copyright © 2017. Published by Elsevier B.V.)- Published
- 2017
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41. An avian-only Filippov model incorporating culling of both susceptible and infected birds in combating avian influenza.
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Chong NS, Dionne B, and Smith R
- Subjects
- Animals, Birds, Disease Outbreaks statistics & numerical data, Influenza in Birds transmission, Animal Husbandry methods, Disease Outbreaks prevention & control, Influenza in Birds prevention & control
- Abstract
Depopulation of birds has always been an effective method not only to control the transmission of avian influenza in bird populations but also to eliminate influenza viruses. We introduce a Filippov avian-only model with culling of susceptible and/or infected birds. For each susceptible threshold level [Formula: see text], we derive the phase portrait for the dynamical system as we vary the infected threshold level [Formula: see text], focusing on the existence of endemic states; the endemic states are represented by real equilibria, pseudoequilibria and pseudo-attractors. We show generically that all solutions of this model will approach one of the endemic states. Our results suggest that the spread of avian influenza in bird populations is tolerable if the trajectories converge to the equilibrium point that lies in the region below the threshold level [Formula: see text] or if they converge to one of the pseudoequilibria or a pseudo-attractor on the surface of discontinuity. However, we have to cull birds whenever the solution of this model converges to an equilibrium point that lies in the region above the threshold level [Formula: see text] in order to control the outbreak. Hence a good threshold policy is required to combat bird flu successfully and to prevent overkilling birds.
- Published
- 2016
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42. Erratum to: An avian-only Filippov model incorporating culling of both susceptible and infected birds in combating avian influenza.
- Author
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Chong NS, Dionne B, and Smith R
- Published
- 2016
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43. Potential Ceiling Effect of Healthcare Worker Influenza Vaccination on the Incidence of Nosocomial Influenza Infection.
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Dionne B, Brett M, Culbreath K, and Mercier RC
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- Academic Medical Centers statistics & numerical data, Adolescent, Adult, Age Factors, Aged, Child, Child, Preschool, Cross Infection prevention & control, Cross-Sectional Studies, Humans, Incidence, Infant, Infant, Newborn, Infectious Disease Transmission, Patient-to-Professional prevention & control, Infectious Disease Transmission, Patient-to-Professional statistics & numerical data, Influenza, Human prevention & control, Logistic Models, Middle Aged, Retrospective Studies, Young Adult, Cross Infection epidemiology, Influenza Vaccines therapeutic use, Influenza, Human epidemiology, Personnel, Hospital statistics & numerical data
- Abstract
OBJECTIVE To evaluate the effect of healthcare worker (HCW) influenza vaccination on the incidence of nosocomial influenza DESIGN Retrospective cross-sectional study SETTING A 550-bed tertiary-care academic medical center METHODS All admitted patients with a direct fluorescent antibody (DFA) or polymerase chain reaction (PCR) assay positive for influenza ordered between October 1 and May 31 from 2010 to 2015 were eligible for inclusion. Nosocomial influenza was defined as a positive influenza test collected ≥48 hours after admission in patients without influenza-like illness present within 24 hours of admission. Relative nosocomial influenza frequency was calculated by dividing the number of nosocomial cases by the total number of admitted patients with influenza for each season. A univariate logistic regression was used to determine the association between HCW influenza vaccination coverage and nosocomial influenza. RESULTS Over 5 seasons, 533 patients had positive influenza tests during their hospitalization; 29 of these patients (5.4%) acquired influenza during their hospitalization. HCW vaccination coverage increased over the 5 seasons from 47% to 90% (P<.001). Despite an initial decrease in relative nosocomial influenza frequency during the first year (9% to 4.9%), subsequent seasons failed to show an additional decrease in nosocomial infections (4.3%, 5.2%, and 4.8%, respectively); the overall decrease in nosocomial influenza from the first season to the final season was not significant (P=.282). No association was detected between HCW vaccination coverage and nosocomial influenza (odds ratio [OR], 0.990; 95% confidence interval [CI], 0.970-1.011). CONCLUSION HCW vaccination >50% may not have a significant effect on nosocomial influenza. Infect Control Hosp Epidemiol 2016;37:840-844.
- Published
- 2016
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44. Pulmonary Fungal Infection Caused by Neoscytalidium dimidiatum.
- Author
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Dionne B, Neff L, Lee SA, Sutton DA, Wiederhold NP, Lindner J, Fan H, and Jakeman B
- Subjects
- Antifungal Agents pharmacology, Ascomycota drug effects, Ascomycota genetics, DNA, Fungal chemistry, DNA, Fungal genetics, DNA, Ribosomal Spacer chemistry, DNA, Ribosomal Spacer genetics, Humans, Immunocompromised Host, Lung Diseases, Fungal microbiology, Male, Microbial Sensitivity Tests, Microscopy, Middle Aged, Molecular Sequence Data, Opportunistic Infections diagnosis, Opportunistic Infections microbiology, Opportunistic Infections pathology, Sequence Analysis, DNA, Ascomycota classification, Ascomycota isolation & purification, Lung Diseases, Fungal diagnosis, Lung Diseases, Fungal pathology
- Abstract
Neoscytalidium dimidiatum is a mold known to cause onychomycosis and dermatomycosis; however, it is an extremely rare cause of systemic infection. We report a case of pulmonary infection with Neoscytalidium dimidiatum in an immunocompromised patient and discuss in vitro susceptibility data from this case and previous literature., (Copyright © 2015, American Society for Microbiology. All Rights Reserved.)
- Published
- 2015
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45. Different immunity elicited by recombinant H5N1 hemagglutinin proteins containing pauci-mannose, high-mannose, or complex type N-glycans.
- Author
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Lin SC, Jan JT, Dionne B, Butler M, Huang MH, Wu CY, Wong CH, and Wu SC
- Subjects
- Animals, Antibodies, Neutralizing blood, Antibodies, Viral blood, Antibody-Producing Cells metabolism, Antigen-Presenting Cells immunology, CHO Cells, Carbohydrate Conformation, Carbohydrate Sequence, Cricetinae, Cricetulus, Female, Glycosylation, Hemagglutinins chemistry, Hemagglutinins metabolism, Humans, Immunoglobulin Isotypes blood, Influenza Vaccines chemistry, Influenza Vaccines metabolism, Influenza, Human immunology, Influenza, Human prevention & control, Influenza, Human virology, Mannans metabolism, Mice, Mice, Inbred BALB C, Models, Molecular, Molecular Sequence Data, Protein Structure, Tertiary, Sf9 Cells, Spodoptera, T-Lymphocytes immunology, Vaccination, Viral Proteins chemistry, Viral Proteins metabolism, Hemagglutinins immunology, Influenza A Virus, H5N1 Subtype immunology, Influenza Vaccines immunology, Protein Processing, Post-Translational, Viral Proteins immunology
- Abstract
Highly pathogenic avian influenza H5N1 viruses can result in poultry and occasionally in human mortality. A safe and effective H5N1 vaccine is urgently needed to reduce the pandemic potential. Hemagglutinin (HA), a major envelope protein accounting for approximately 80% of spikes in influenza virus, is often used as a major antigen for subunit vaccine development. In this study, we conducted a systematic study of the immune response against influenza virus infection following immunization with recombinant HA proteins expressed in insect (Sf9) cells, insect cells that contain exogenous genes for elaborating N-linked glycans (Mimic) and mammalian cells (CHO). While the antibody titers are higher with the insect cell derived HA proteins, the neutralization and HA inhibition titers are much higher with the mammalian cell produced HA proteins. Recombinant HA proteins containing tri- or tetra-antennary complex, terminally sialylated and asialyated-galactose type N-glycans induced better protective immunity in mice to lethal challenge. The results are highly relevant to issues that should be considered in the production of fragment vaccines.
- Published
- 2013
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46. Fed-batch CHO cell t-PA production and feed glutamine replacement to reduce ammonia production.
- Author
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Kim DY, Chaudhry MA, Kennard ML, Jardon MA, Braasch K, Dionne B, Butler M, and Piret JM
- Subjects
- Animals, CHO Cells, Cell Culture Techniques, Cell Survival, Cells, Cultured, Cricetinae, Cricetulus, Culture Media metabolism, Glutamine metabolism, Oxidation-Reduction, Ammonia metabolism, Culture Media chemistry, Glutamine chemistry, Tissue Plasminogen Activator biosynthesis
- Abstract
Industrial therapeutic protein production has been greatly improved through fed-batch development. In this study, improvement to the productivity of a tissue-plasminogen activator (t-PA) expressing Chinese hamster ovary (CHO) cell line was investigated in shake flask culture through the optimization of the fed-batch feed and the reduction of ammonia generation by glutamine replacement. The t-PA titer was increased from 33 mg/L under batch conditions to 250 mg/L with daily feeding starting after three days of culture. A commercially available fed-batch feed was supplemented with cotton seed hydrolysate and the four depleted amino acids, aspartic acid, asparagine, cysteine, and tyrosine. The fed-batch operation increased the generation of by-products such as lactate and ammonia that can adversely affect the fed-batch performance. To reduce the ammonia production, a glutamine-containing dipeptide, pyruvate, glutamate, and wheat gluten hydrolysate, were investigated as glutamine substitutes. To minimize the lag phase as the cells adjusted to the new energy source, a feed glutamine replacement process was developed where the cells were initially cultured with a glutamine containing basal medium to establish cell growth followed by feeding with a feed containing the glutamine substitutes. This two-step feed glutamine replacement process not only reduced the ammonia levels by over 45% but, in the case of using wheat gluten hydrolysate, almost doubled the t-PA titer to over 420 mg/L without compromising the t-PA product quality or glycosylation pattern. The feed glutamine replacement process combined with optimizing other feed medium components provided a simple, practical, and effective fed-batch strategy that could be applied to the production of other recombinant therapeutic proteins., (Copyright © 2012 American Institute of Chemical Engineers (AIChE).)
- Published
- 2013
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47. Precepting the medical assistant practicum: expectations and rewards: an evaluation of preceptors' opinions.
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Wilson AB, Fegan F, Romence B, Uhe K, and Dionne B
- Subjects
- Education, Continuing methods, Education, Continuing standards, Faculty, Humans, Reward, Surveys and Questionnaires, Workforce, Allied Health Personnel education, Attitude of Health Personnel, Preceptorship standards
- Abstract
Unlabelled: This study investigated the opinions of preceptors on select topics relevant to the benefits and rewards of precepting medical assisting (MA) students., Methods: A 35-item questionnaire was distributed to volunteer MA preceptors over the course of 1 year. Survey items prompted participants for information concerning background and previous experiences with MA students, as well as gathered opinions on the benefits, issues, and rewards of preceptorships., Results: Of the preceptors who gave evidence of their credentials, 98.43% were either practicing certified medical assistants (CMA-AAMA) or nurses. Respectively, 80.85% of CMAs and 80.00% of nurses felt that students provided the office with extra help and placed no financial burden on the practice. Approximately 44% ranked free continuing medical education (CME) credits as the most important reward. Written responses identified thank-you notes as an important demonstration of service, acknowledgment, and appreciation., Conclusion: MA preceptors consider students a beneficial aspect of their practice because they lighten strenuous workloads and stimulate preceptors to remain current in their professional fields. Noncompensated MA preceptors value both extrinsic (e.g., free CME credits) and intrinsic rewards (e.g., feedback and thank-you cards) and suggested that intrinsic rewards were of greater value.
- Published
- 2011
48. Pleural effusions following cardiac surgery: prevalence, risk factors, and clinical features.
- Author
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Labidi M, Baillot R, Dionne B, Lacasse Y, Maltais F, and Boulet LP
- Subjects
- Aged, Anti-Arrhythmia Agents adverse effects, Anti-Arrhythmia Agents therapeutic use, Anticoagulants adverse effects, Anticoagulants therapeutic use, Cardiovascular Diseases complications, Cardiovascular Diseases drug therapy, Drainage, Female, Humans, Male, Middle Aged, Pleural Effusion therapy, Prevalence, Retrospective Studies, Risk Factors, Sex Characteristics, Cardiovascular Surgical Procedures adverse effects, Pleural Effusion epidemiology, Pleural Effusion etiology
- Abstract
Background: Pleural effusion is a common complication of cardiac surgery, but its characteristics and predisposing factors should be documented further. Our objective was to determine the prevalence, characteristics, and determinants of clinically significant pleural effusions, defined as those requiring therapeutic pleural drainage according to clinical assessment., Methods: The prevalence and characteristics of patients who had a pleural effusion within 30 days of undergoing coronary artery bypass graft, valve replacement, or both were analyzed retrospectively at our institution over a 2-year period., Results: Among the 2,892 patients included in the study (mean age, 66 years; men, 2,139), 192 patients (6.6%) had experienced a clinically significant pleural effusion in the 30 days postsurgery. These effusions occurred after a mean (+/- SD) duration of 6.6 +/- 5.9 days following interventions. Pleural fluid analysis was obtained in 114 patients (59.4%); all met the criteria for an exudate. Pleural fluid was hemorrhagic in 50% of cases. Age, body weight, baseline pulmonary function, and smoking status were similar between patients with and without effusion; however, the proportion of women; the number of patients with previous conditions of heart failure, atrial fibrillation, or peripheral vascular disease; and the number of patients receiving therapy with an anticoagulant or antiarrhythmic agent was higher in the pleural effusion group. Patients with pleural effusion had an increased prevalence of postoperative complications., Conclusions: Pleural effusion is a common complication of heart surgery, is associated with other postoperative complications, and is more frequent in women and in patients with associated cardiac or vascular comorbidities and medications used to treat those conditions., Trial Registration: ClinicalTrials.gov Identifier: NCT00665015.
- Published
- 2009
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49. Recent evolution in demographic and clinical characteristics and in-hospital morbidity in patients undergoing coronary surgery.
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Baillot RG, Joanisse DR, Stevens LM, Doyle DP, Dionne B, and Lellouche F
- Subjects
- Adult, Age Factors, Aged, Aged, 80 and over, Cohort Studies, Coronary Angiography, Coronary Artery Bypass methods, Coronary Artery Bypass, Off-Pump methods, Coronary Artery Bypass, Off-Pump mortality, Coronary Disease diagnostic imaging, Female, Humans, Male, Myocardial Revascularization methods, Myocardial Revascularization mortality, Postoperative Complications mortality, Prognosis, Quebec, Registries, Reoperation statistics & numerical data, Retrospective Studies, Risk Assessment, Severity of Illness Index, Sex Factors, Survival Analysis, Coronary Artery Bypass mortality, Coronary Disease mortality, Coronary Disease surgery, Hospital Mortality trends
- Abstract
Background: Over the last 12 years, the demographic and clinical characteristics of patients undergoing myocardial revascularization surgery have evolved rapidly. The goal of our study was to analyze the evolution of these trends and the results of these surgical interventions., Methods: We identified patients who underwent a first or second myocardial revascularization between 1993 and 2004, and we arbitrarily divided them into 2 groups: 1 cohort of patients who underwent surgery between 1993 and 1998 and 1 cohort of patients who underwent surgery between 1999 and 2004. We compared demographic and clinical characteristics between the 2 cohorts and determined which variables were significant predictors of morbidity and mortality., Results: From 1993 to 2004, 12 202 patients underwent a first (95.5%) or second (4.5%) myocardial revascularization. Patients in the later cohort presented with a high-risk profile. They were older and had metabolic syndrome or diabetes and peripheral vascular disease. On the other hand, there were fewer active smokers in this group. Whereas the rate of postoperative infarction and renal insufficiency was higher in the second cohort, this group had a lower incidence of stroke and prolonged mechanical ventilation and shorter hospital stays. Overall, observed mortality decreased in spite of a steady increase in predicted mortality. Identified predictors of mortality were age, stroke, female sex, nonelective surgery, renal insufficiency, peripheral vascular disease, chronic obstructive pulmonary disease, ventricular dysfunction and stenosis of the left main trunk., Conclusion: Our study confirmed current trends that show an increase in the at-risk population with dysmetabolic syndrome in cardiac surgery, as well as constant improvements in tertiary care in anesthesia and coronary surgery.
- Published
- 2009
50. Protein-free fed-batch culture of non-GS NS0 cell lines for production of recombinant antibodies.
- Author
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Burky JE, Wesson MC, Young A, Farnsworth S, Dionne B, Zhu Y, Hartman TE, Qu L, Zhou W, and Sauer PW
- Subjects
- Animals, Antibodies, Monoclonal immunology, Bioreactors, Cell Culture Techniques methods, Cell Line, Cholesterol pharmacology, Humans, Mice, Recombinant Proteins biosynthesis, Recombinant Proteins immunology, Antibodies, Monoclonal biosynthesis
- Abstract
Presented is a novel antibody production platform based on the fed-batch culture of recombinant, NS0-derived cell lines. A standardized fed-batch cell culture process was developed for five non-GS NS0 cell lines using enriched and optimized protein-free, cholesterol-free, and chemically defined basal and feed media. The process performed reproducibly and scaled faithfully from the 2-L to the 100-L bioreactor scale achieving a volumetric productivity of > 120 mg/L per day. Fed-batch cultures for all five cell lines exhibited significant lactate consumption when the cells entered the stationary or death phase. Peak and final lactate concentrations were low relative to a previously developed fed-batch process (FBP). Such low lactate production and high lactate consumption rates were unanticipated considering the fed-batch culture basal medium has an unconventionally high initial glucose concentration of 15 g/L, and an overall glucose consumption in excess of 17 g/L. The potential of this process platform was further demonstrated through additional media optimization, which has resulted in a final antibody concentration of 2.64 +/- 0.19 g/L and volumetric productivity of > 200 mg/L per day in a 13-day FBP for one of the five production cell lines. Use of this standardized protein-free, cholesterol-free NS0 FBP platform enables consistency in development time and cost effectiveness for manufacturing of therapeutic antibodies., ((c) 2006 Wiley Periodicals, Inc.)
- Published
- 2007
- Full Text
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