Document Detail


Confinement regulates complex biochemical networks: initiation of blood clotting by "diffusion acting".
MedLine Citation:
PMID:  19843446     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study shows that environmental confinement strongly affects the activation of nonlinear reaction networks, such as blood coagulation (clotting), by small quantities of activators. Blood coagulation is sensitive to the local concentration of soluble activators, initiating only when the activators surpass a threshold concentration, and therefore is regulated by mass transport phenomena such as flow and diffusion. Here, diffusion was limited by decreasing the size of microfluidic chambers, and it was found that microparticles carrying either the classical stimulus, tissue factor, or a bacterial stimulus, Bacillus cereus, initiated coagulation of human platelet-poor plasma only when confined. A simple analytical argument and numerical model were used to describe the mechanism for this phenomenon: confinement causes diffusible activators to accumulate locally and surpass the threshold concentration. To interpret the results, a dimensionless confinement number, Cn, was used to describe whether a stimulus was confined, and a Damköhler number, Da(2), was used to describe whether a subthreshold stimulus could initiate coagulation. In the context of initiation of coagulation by bacteria, this mechanism can be thought of as "diffusion acting", which is distinct from "diffusion sensing". The ability of confinement and diffusion acting to change the outcome of coagulation suggests that confinement should also regulate other biological "on" and "off" processes that are controlled by thresholds.
Authors:
Feng Shen; Rebecca R Pompano; Christian J Kastrup; Rustem F Ismagilov
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Biophysical journal     Volume:  97     ISSN:  1542-0086     ISO Abbreviation:  Biophys. J.     Publication Date:  2009 Oct 
Date Detail:
Created Date:  2009-10-21     Completed Date:  2010-02-12     Revised Date:  2010-10-22    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2137-45     Citation Subset:  IM    
Affiliation:
Department of Chemistry and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois, USA.
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MeSH Terms
Descriptor/Qualifier:
Algorithms
Bacillus cereus
Blood Coagulation / physiology*
Computer Simulation
Diffusion*
Environment
Enzyme Precursors / metabolism
Fluorescence
Humans
Kinetics
Linear Models
Microfluidic Analytical Techniques
Models, Biological*
Nonlinear Dynamics
Plasma / physiology
Thrombin / metabolism
Thromboplastin / metabolism
Chemical
Reg. No./Substance:
0/Enzyme Precursors; 9035-58-9/Thromboplastin; EC 3.4.21.-/meizothrombin; EC 3.4.21.5/Thrombin

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