The Experts below are selected from a list of 117 Experts worldwide ranked by ideXlab platform
Ronald L Fournier - One of the best experts on this subject based on the ideXlab platform.
-
oxygen and inulin transport measurements in a planar tissue engineered Bioartificial Organ
Tissue Engineering, 2002Co-Authors: Zhan Ding, Ronald L FournierAbstract:In vivo oxygen and inulin transport rates were measured in a planar tissue-engineered Bioartificial Organ implanted in a rat. A compartmental model was used to describe the transport of oxygen and inulin between the cell chamber, across the immunoisolation membrane, and within the neovascularized region adjacent to the immunoisolation membrane. A nonlinear regression analysis of the plasma inulin levels and the oxygen transport rate into the device provided information on the degree of vascularization in the region adjacent to the Bioartificial Organ. Key parameters that were obtained from the analysis of the in vivo transport data included the average capillary blood oxygen partial pressure, the Krogh tissue cylinder radius, the extracellular volume fraction, and the capillary blood residence time. These four parameters are important indicators for assessing the degree of vascularization in the tissue adjacent to the immunoisolation membrane in the Bioartificial Organ. The oxygen and inulin transport tec...
-
in vivo measurement of solute transport rates in a Bioartificial Organ
Tissue Engineering, 1999Co-Authors: Julie A Krohn, Ronald L Fournier, Andrew R Baker, Jennifer L Long, James P ByersAbstract:A radioactive tracer technique was used to evaluate the in vivo mass transfer properties of a tissue engineered Bioartificial Organ. To obtain these measurements, Bioartificial Organs were first im...
-
method for measuring in vivo oxygen transport rates in a Bioartificial Organ
Tissue Engineering, 1999Co-Authors: David W Whalen, Zhan Ding, Ronald L FournierAbstract:Oxygen transport is crucial for the proper functioning of a Bioartificial Organ. In many cases, the immunoisolation membrane used to protect the transplanted cells from the host's immune system can be a significant barrier to oxygen transport. A method is described for measuring the in vitro and in vivo oxygen transport characteristics of a planar immunoisolation membrane. The in vitro oxygen permeability of the membrane was found to equal 9.22 × 10−4 cm/sec and was essentially the same as the in vivo value of 9.51 × 10−4 cm/sec. The fact that the in vitro and in vivo membrane permeabilities are identical indicates that any fibrotic tissue adjacent to the immunoisolation membrane did not present a significant resistance to the transport of oxygen. The measured oxygen permeability was also found consistent with the solute permeabilities obtained in a previous study for larger molecules. Based on the oxygen permeability results, theoretical calculations for this particular membrane indicate that about 1,100...
-
Basic Transport Phenomena in Biomedical Engineering
1998Co-Authors: Ronald L FournierAbstract:1. INTRODUCTION 1.1 Review of units and dimensions 1.1.1 Units 1.1.2 Fundamental dimensions 1.1.2.1 Mass and weight 1.1.2.2 Temperature 1.1.2.3 Mole 1.1.3 Derived dimensional quantities 1.1.3.1 Pressure 1.1.3.2 Volume 1.1.3.3 Equations of state 1.2 Dimensional equation 1.3 Tips for solving engineering problems 1.4 Conservation of mass 1.4.1 Law of conservation 1.4.2 Chemical reactions 1.4.3 Material balances 2. A REVIEW OF THERMODYNAMIC CONCEPTS 2.1 The first law of thermodynamics 2.1.1 Closed systems 2.1.2 Steady flow systems 2.2 The second law of thermodynamics 2.2.1 Reversible processes 2.3 Properties 2.3.1 Heat capacity 2.3.2 Calculating the change in entropy 2.3.1.1 Entropy change of an ideal gas 2.3.3 The Gibbs and Helmholtz free energy 2.3.3.1 Gibbs free energy 2.3.3.2 Helmholtz free energy 2.4 The fundamental property relations 2.4.1 Exact differentials 2.5 Single phase open systems 2.5.1 Partial molar properties 2.5.1.1. Binary systems 2.5.1.2 Property changes of mixing 2.5.1.3 Ideal gas 2.5.1.4 Gibbs free energy of an ideal gas mixture 2.5.2 Pure component fugacity 2.5.2.1 Calculating the pure component fugacity 2.5.3 Fugacity of a component in a mixture 2.5.4 The ideal solution 2.6 Phase equilibrium 2.6.1 Pure component phase equilibrium 2.6.1.1 Fugacity of a pure component as compressed liquid 2.6.2 Excess properties 2.6.3 Phase equilibrium in mixtures 2.6.3.1 Solubility of a solid in a liquid solvent 2.6.3.2 Depression of the freezing point of a solvent by a solute 2.6.3.3 Equilibrium between a solid and a gas phase 2.6.3.4 Solubility of a gas in a liquid 2.6.3.5 Osmotic pressure 2.6.3.6 Distribution of a solute between two liquid phases 2.6.3.7 Vapor-liquid equilibrium 2.6.3.8 Flammability limits 2.6.3.9 Thermodynamics of surfaces 3. Physical Properties of the Body Fluids and the Cell Membrane 3.1 Body fluids 3.2 Fluid compositions 3.3 Capillary plasma protein retention 3.4 Osmotic pressure 3.4.1 Osmolarity 3.4.2 Calculating the osmotic pressure 3.4.3 Other factors that may affect the osmotic pressure 3.5 Formation of the interstitial fluid 3.6 Net capillary filtration rate 3.7 Lymphatic system 3.8 Solute transport across the capillary endothelium 3.9 The cell membrane 3.10 Ion pumps 4. The Physical and Flow Properties of Blood 4.1 Physical properties of blood 4.2 Cellular components 4.3 Rheology 4.4 Relationship between shear stress and shear rate 4.5 Hagan-Poiseuille equation 4.6 Other useful flow relationships 4.7 Rheology of blood 4.8 The Casson equation 4.9 Using the Casson equation 4.10 The velocity profile for tube flow of a Casson fluid 4.11 Tube flow of blood at low shear rates 4.12 The effect of the diameter at high shear rates 4.13 Marginal zone theory 4.14 Using the marginal zone theory 4.15 Boundary layer theory 4.15.1 The flow near a wall that is set in motion 4.15.2 Laminar flow of a fluid along a flat plate 4.16 Generalized mechanical energy balance equation 4.17 Capillary rise and capillary action 4.17.1 Capillary rise 4.17.2 Dynamics of capillary rise 5. Solute Transport in Biological Systems 5.1 Description of solute transport in biological systems 5.2 Capillary properties 5.3 Capillary flowrates 5.4 Solute diffusion 5.4.1 Fick's first and second law 5.4.2 Mass transfer in laminar boundary layer flow over a flat plate 5.4.3 Mass transfer from the walls of a tube containing a fluid in laminar flow 5.4.4 Mass transfer coefficient correlations 5.4.5 Determining the diffusivity 5.5 Solute transport by capillary filtration 5.6 Solute diffusion within heterogeneous media 5.6.1 Diffusion of a solute from a polymeric material 5.6.1.1 A solution valid for short contact times 5.6.2 Diffusion in blood and tissue 5.7 Solute permeability 5.8 The irreversible thermodynamics of membrane transport 5.8.1 Finding Lp , Pm , and s 5.8.2 Multicomponent membrane transport 5.9 Transport of solutes across the capillary wall 5.10 Transport of solute between a capillary and the surrounding tissue space 5.10.1 The Krogh tissue cylinder 5.10.2 A model of the Krogh tissue cylinder 5.10.2.1 A comparison of convection and diffusion effects 5.10.2.2 The Renkin-Crone equation 5.10.2.3 Determining the value of PmS 5.10.3 Solute transport in vascular beds 6. Oxygen Transport in Biological Systems 6.1 The diffusion of oxygen in multicellular systems 6.2 Hemoglobin 6.3 The hemoglobin-oxygen dissociation curve 6.4 Oxygen levels in blood 6.5 The Hill equation 6.6 Other factors that can affect the oxygen dissociation curve 6.7 Tissue oxygenation 6.8 Oxygen transport in a Bioartificial Organ 6.9 Steady state oxygen transport in perfusion bioreactors 6.10 Oxygen transport in the Krogh tissue cylinder 6.11 An approximate solution for oxygen transport in the Krogh tissue cylinder 6.12 Artificial blood 7. Pharmacokinetic Analysis 7.1 Terminology 7.2 Entry routes for drugs 7.3 Modeling approaches 7.4 Factors that affect drug distribution 7.4.1 Drug distribution volumes 7.4.2 Drug metabolism 7.4.3 Renal excretion of the drug 7.5 Drug clearance 7.5.1 Renal clearance 7.5.2 Plasma clearance 7.5.3 Biological half-life 7.6 A model for intravenous injection of drug 7.7 Accumulation of drug in the urine 7.8 Constant infusion of drug 7.8.1 Application to controlled release of drugs by osmotic pumps 7.8.2 Application to the transdermal delivery of drugs 7.8.2.1 Predicting the permeability of the skin 7.9 First order drug absorption and elimination 7.10 Two compartment models 7.10.1 A two compartment model for an intravenous injection 7.10.2 A two compartment model for first order absorption 8. Extracorporeal Devices 8.1 Applications 8.2 Contacting schemes 8.3 Membrane solute transport 8.4 Estimating the mass transfer coefficients 8.5 Estimating the solute diffusivity in blood 8.6 Hemodialysis 8.6.1 Background 8.2.1 Dialysate composition 8.6.3 Role of ultrafiltration 8.6.4 Clearance and dialysance 8.6.5 Solute transfer 8.6.6 A single compartment model of urea dialysis 8.6.7 Peritoneal dialysis 8.7 Blood Oxygenators 8.7.1 Background 8.7.2 Operating characteristics 8.7.3 Types of oxygenators 8.7.4 Analysis of a membrane oxygenator, oxygen transfer 8.7.5 Analysis of a membrane oxygenator, carbon dioxide transfer 8.7.6 Example calculations for membrane oxygenators 8.8 Immobilized Enzyme Reactors 8.8.1 Background 8.8.2 Examples of medical applications of immobilized enzymes 8.8.3 Enzyme reaction kinetics 8.8.4 Reaction and diffusion in immobilized enzyme systems 8.8.5 Solving the immobilized enzyme reaction-diffusion model 8.8.6 Special case of a first order reaction 8.8.7 Observed reaction rate 8.8.8 External mass transfer resistance 8.8.9 Reactor design equations 8.8.9.1 Packed bed reactor 8.8.9.2 Well-mixed reactor 8.9 Affinity adsorption 9. Tissue Engineering 9.1 Introduction 9.2 Cell transplantation 9.3 The extracellular matrix (ECM) 9.3.1 Glycosaminoglycans 9.3.2 Collagens 9.3.3 Elastin 9.3.4 Fibronectin 9.3.5 Basement membrane 9.4 Cellular interactions 9.4.1 Cadherins 9.4.2 Selectins 9.4.3 Cell adhesion molecules 9.4.4 Integrins 9.4.5 Cytokines and growth factors 9.5 Polymeric support structures 9.6 Initial response to an implant 9.7 Tissue ingrowth in porous polymeric structures 9.8 Capillary volume fractions 9.9 Measuring the blood flow within polymeric support structures 9.10 Measuring mass transfer rates 9.11 Pharmacokinetic modelling of inulin transport in a polymeric support stucture 9.12 Cell transplantation into polymeric support structures 10. Bioartificial Organs 10.1 Background 10.2 Some immunology 10.2.1 B-lymphocytes 10.2.2 Antibodies 10.2.3 T Lymphocytes 10.2.4 Interaction between APCs, B cells, and T cells 10.2.5 The immune system and transplanted cells 10.3 Immunoisolation 10.4 Permeability of immunoisolation membranes 10.5 Membrane Sherwood number 10.6 Bioartificial Organs 10.6.1 The Bioartificial pancreas 10.6.1.1 Bioartificial pancreas approaches 10.6.1.2 Intravascular devices 10.6.1.3 Microencapsulation 10.6.1.4 Macroencapsulation 10.6.1.5 Organoid 10.7 Number of islets needed 10.8 Islet insulin release model 10.9 Pharmacokinetic modeling of glucose and insulin interactions 10.10 Using the pharmacokinetic model to evaluate the performance of a Bioartificial pancreas 10.11 The Bioartificial liver 10.11.1 Artificial liver systems 10.11.2 Bioartificial livers 10.11.3 Three extracorporeal Bioartificial livers 10.12 The Bioartificial kidney 10.12.1 Two configurations for a Bioartificial kidney Index
Norio Ohshima - One of the best experts on this subject based on the ideXlab platform.
-
Packed-bed type reactor to attain high density culture of hepatocytes for use as a Bioartificial liver.
Artificial Organs, 2008Co-Authors: Norio Ohshima, Kennichi Yanagi, Hirotoshi MiyoshiAbstract:: In an attempt to develop a Bioartificial liver using cultured hepatocytes, we investigated the short-term and long-term viability and metabolic functions of hepatocytes cultured in a new type of packed-bed type reactor using reticulated polyvinyl formal (PVF) resin as a supporting material. Perfusion culture experiments using this reactor, as well as monolayer cultures using conventional collagen-coated Petri dishes as control experiments, were performed. It was found that the highest density of immobilized hepatocytes attained with PVF resin was on the order of 107 cells/cm3 PVF and that hepatocytes cultured in this type of module for up to a week showed a sufficient level of liver-specific metabolic functions, such as ammonium metabolism, urea-N synthesis, and albumin secretion, to be comparable to those in the monolayer culture. It is concluded that the packed-bed reactor system utilizing PVF resin is a promising means to develop a Bioartificial Organ using hepatocytes.
-
A packed-bed reactor utilizing porous resin enables high density culture of hepatocytes
Applied Microbiology and Biotechnology, 1992Co-Authors: Kennichi Yanagi, Hirotoshi Miyoshi, Hideki Fukuda, Norio OhshimaAbstract:To enable high density culture of hepatocytes for use as a hybrid artificial liver support system or a bioreactor system, a packed-bed reactor using collagen-coated reticulated polyvinyl formal (PVF) resin was applied to a primary culture of hepatocytes. Cubic PVF resins (2×2×2 mm, mean pore size: 100, 250 or 500 μm) were used as supporting substrates to immobilize hepatocytes. Two hundred and fifty cubes were packed in a cylindrical column, and 2.6–11.3×10^7 hepatocytes were seeded in the column by irrigating with 3 ml of the medium containing hepatocytes. Perfusion culture experiments using this packed-bed reactor, as well as monolayer cultures using conventional collagen-coated petri dishes as control experiments, were performed. Sufficient amounts of hepatocytes were found to be immobilized in the reticulated structure of the PVF resins. The highest density of immobilized hepatocytes attained with PVF resin was 1.2×10^7 cells/cm^3 PVF, which showed levels of ammonium removal and urea-N secretion comparable to those in the monolayer culture. It is concluded that the packed-bed reactor system utilizing PVF resin is a promising process for developing a bioreactor or a Bioartificial Organ using hepatocytes.
Zhan Ding - One of the best experts on this subject based on the ideXlab platform.
-
oxygen and inulin transport measurements in a planar tissue engineered Bioartificial Organ
Tissue Engineering, 2002Co-Authors: Zhan Ding, Ronald L FournierAbstract:In vivo oxygen and inulin transport rates were measured in a planar tissue-engineered Bioartificial Organ implanted in a rat. A compartmental model was used to describe the transport of oxygen and inulin between the cell chamber, across the immunoisolation membrane, and within the neovascularized region adjacent to the immunoisolation membrane. A nonlinear regression analysis of the plasma inulin levels and the oxygen transport rate into the device provided information on the degree of vascularization in the region adjacent to the Bioartificial Organ. Key parameters that were obtained from the analysis of the in vivo transport data included the average capillary blood oxygen partial pressure, the Krogh tissue cylinder radius, the extracellular volume fraction, and the capillary blood residence time. These four parameters are important indicators for assessing the degree of vascularization in the tissue adjacent to the immunoisolation membrane in the Bioartificial Organ. The oxygen and inulin transport tec...
-
method for measuring in vivo oxygen transport rates in a Bioartificial Organ
Tissue Engineering, 1999Co-Authors: David W Whalen, Zhan Ding, Ronald L FournierAbstract:Oxygen transport is crucial for the proper functioning of a Bioartificial Organ. In many cases, the immunoisolation membrane used to protect the transplanted cells from the host's immune system can be a significant barrier to oxygen transport. A method is described for measuring the in vitro and in vivo oxygen transport characteristics of a planar immunoisolation membrane. The in vitro oxygen permeability of the membrane was found to equal 9.22 × 10−4 cm/sec and was essentially the same as the in vivo value of 9.51 × 10−4 cm/sec. The fact that the in vitro and in vivo membrane permeabilities are identical indicates that any fibrotic tissue adjacent to the immunoisolation membrane did not present a significant resistance to the transport of oxygen. The measured oxygen permeability was also found consistent with the solute permeabilities obtained in a previous study for larger molecules. Based on the oxygen permeability results, theoretical calculations for this particular membrane indicate that about 1,100...
Xiaohong Wang - One of the best experts on this subject based on the ideXlab platform.
-
Bioartificial Organ manufacturing technologies
Cell Transplantation, 2019Co-Authors: Xiaohong WangAbstract:Bioartificial Organ manufacturing technologies are a series of enabling techniques that can be used to produce human Organs based on bionic principles. During the last ten years, significant progre...
-
Natural Polymers for Organ 3D Bioprinting.
Polymers, 2018Co-Authors: Qiuhong Chen, Qiang Ao, Xiaohong Tian, Hao Tong, Xiaohong WangAbstract:Three-dimensional (3D) bioprinting, known as a promising technology for Bioartificial Organ manufacturing, has provided unprecedented versatility to manipulate cells and other biomaterials with precise control their locations in space. Over the last decade, a number of 3D bioprinting technologies have been explored. Natural polymers have played a central role in supporting the cellular and biomolecular activities before, during and after the 3D bioprinting processes. These polymers have been widely used as effective cell-loading hydrogels for homogeneous/heterogeneous tissue/Organ formation, hierarchical vascular/neural/lymphatic network construction, as well as multiple biological/biochemial/physiological/biomedical/pathological functionality realization. This review aims to cover recent progress in natural polymers for Bioartificial Organ 3D bioprinting. It is structured as introducing the important properties of 3D printable natural polymers, successful models of 3D tissue/Organ construction and typical technologies for Bioartificial Organ 3D bioprinting.
Stephen M Pastores - One of the best experts on this subject based on the ideXlab platform.
-
Bioartificial Organ support for hepatic renal and hematologic failure
Critical Care Clinics, 2000Co-Authors: Patrick J Maguire, Christopher Stevens, David H Humes, Aryeh Shander, Neil A Halpern, Stephen M PastoresAbstract:Recent advances in our understanding of the cellular and molecular basis of Organ function and disease processes have paved the way for the introduction of novel and exciting therapies to support critically ill patients with single or multiple Organ failure. This article explores the use of "Bioartificial" Organs and focuses on extracorporeal hepatocyte and renal tubule cell assist devices for the treatment of hepatic and renal failure, respectively, and intracorporeal oxygen carriers for the treatment of hematologic failure.
