scholarly journals REEVALUATION OF HYDROGEN CLEARANCE METHOD FOR THE LIVER BASED ON AN ANALYSIS OF A MATHEMATICAL MODEL

1983 ◽  
Vol 16 (9) ◽  
pp. 1731-1731
Author(s):  
Makoto UMEMORI ◽  
Koji SASAJIMA ◽  
Masahiko ONDA ◽  
Akiro SHIROTA
Keyword(s):  
Mathematical Model ◽  
Hydrogen Clearance Method ◽  
Hydrogen Clearance

Measurement of local blood flow of the intestine by hydrogen clearance method; Experimental study

1979 ◽  
Vol 9 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Yoshio Mishima ◽  
Hiroshi Shigematsu ◽  
Yoshiaki Horie ◽  
Masanori Satoh
Keyword(s):  
Experimental Study ◽  
Blood Flow ◽  
Local Blood Flow ◽  
Hydrogen Clearance Method ◽  
Hydrogen Clearance

scholarly journals Hydrogen Clearance Method for Determining Local Cerebral Blood Flow. I. Spatial Resolution

1986 ◽  
Vol 6 (4) ◽  
pp. 486-491 ◽  
Author(s):  
Rüdiger von Kummer ◽  
Sigrid Herold
Keyword(s):  
White Matter ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Local Cerebral Blood Flow ◽  
Hydrogen Clearance Method ◽  
Significant Difference ◽  
Cat Brain ◽  
The Mean ◽  
Burr Holes ◽  
Hydrogen Clearance

To define the effective spatial resolution of the hydrogen clearance method, serial local CBF (LCBF) measurements were performed at different distances from the cortico–white matter junction of the cat brain. Twenty-five platinum-wire microelectrodes with a sensitive surface of 0.07 mm2 were inserted into the cerebral cortex of three cats through burr holes in the skull and advanced toward the ear-to-ear level in 1- or 0.1-mm steps. Most electrodes passed from high-perfusion regions into low-perfusion areas, indicating that the cortico–white matter junction had been traversed. Whereas within the gray and white matter the LCBF values were fairly constant, a striking decrease of CBF was registered at the cortico–white matter junction. Here the mean LCBF from 12 electrodes showed significant differences in flow between two locations 1 mm apart. On two occasions, a significant difference in CBF was found for locations only 0.1 mm apart. Despite this high spatial resolution, monoexponential clearance curves were detected only in the vicinity of the cortico–white matter junction. It is therefore assumed that factors other than flow might influence H2 clearance.

scholarly journals Modelling of hydrogen diffusion in the retina

2020 ◽  
Vol 61 ◽  
pp. C119-C136
Author(s):  
Wafaa Mansoor ◽  
Graeme Hocking ◽  
Duncan Farrow
Keyword(s):  
Mathematical Model ◽  
Blood Flow ◽  
Oxygen Transport ◽  
Hydrogen Diffusion ◽  
Theoretical Models ◽  
Retinal Blood Flow ◽  
Inert Gas ◽  
Mathematical Methods ◽  
Physiol Heart Circ ◽  
Hydrogen Clearance

A simple mathematical model for diffusion of hydrogen within the retina has been developed. The model consists of three, well-mixed, one dimensional layers that exchange hydrogen via a diffusion process. A Fourier series method is applied to compute the hydrogen concentration. The effect of important parameters is examined and discussed. The results may contribute to an understanding of the hydrogen clearance technique to estimate blood flow. A two dimensional numerical method for the hydrogen diffusion is also presented. It is shown that the predominant features of the process are captured quite well by the simpler model. References V. A. Alder, D. Y. Yu, S. J. Cringle and E. N. Su. Experimental approaches to diabetic retinopathy. Asia-Pac. J. Ophthalmol. 4:20–25, 1992. J. C. Arciero, P. Causin and F. Malgoroli. Mathematical methods for modeling the microcirculation. AIMS Biophys. 4:362–399, 2017. doi:10.3934/biophy.2017.3.362 D. E. Farrow, G. C. Hocking, S. J. Cringle and D.-Y. Yu. Modeling Hydrogen clearance from the retina. ANZIAM J. 59:281–292, 2018. doi:10.1017/S1446181117000426 A. B. Friedland. A mathematical model of transmural transport of oxygen to the retina. Bull. Math. Biol. 40:823–837, 2018; doi:10.1007/BF02460609 D. Goldman. Theoretical models of microvascular oxygen transport to tissue. Microcirculation 15:795–811, 2008. doi:10.1080/10739680801938289 A. C. Hindmarsh. ODEPACK, A Systematized Collection of ODE Solvers. In Scientific Computing, R. S. Stepleman, et al., Eds., pp. 55-64. North-Holland, Amsterdam, 1983. S. S. Kety. The theory and applications of the exchange of inert gas at the lungs and tissues. Pharmacol. Rev. 3:1–41, 1951. http://pharmrev.aspetjournals.org/content/3/1/1 B. P. Leonard. A stable and accurate convective modelling procedure based on quadratic upstream interpolation. Comput. Methods Appl. Mech. Eng. 19:59–98, 1979. doi:10.1016/0045-7825(79) 90034-3 S. L. Mitchell. Coupling transport and chemistry: numerics, analysis and applications. PhD thesis, University of Bath, UK, 2003. https://researchportal.bath.ac.uk/en/studentTheses/coupling-transport-and-chemistry-numerics-analysis-and-applicatio G. A. Winchell. Mathematical model of inert gas washout from the retina: evaluation of hydrogen washout as a means of determining retinal blood flow in the cat. Master\textquoteright s Thesis, Northwestern University, Evanston, USA, 1983. https://search.library.northwestern.edu/permalink/f/5c25nc/01NWU_ALMA21563278530002441 D. Y. Yu, V. A. Alder and S. J. Cringle. Measurement of blood flow in rat eyes by hydrogen clearance. Am. J. Physiol. (Heart Circ. Physiol.) 261:H960–H968, 1991. doi:10.1152/ajpheart.1991.261.3.H960 D. Y. Yu, S. J. Cringle, V. A. Alder, E. N. Su, and P. K. Yu, Intraretinal oxygen distribution and choroidal regulation in the avascular retina of guinea pigs. Am. J. Physiol. (Heart Circ. Physiol.) 270:H965-H973, 1996. doi:10.1152/ajpheart.1996.270.3.H965 S. Cringle, D.-Y. Yu, V. Alder, E.-N. Su, and P. Yu. Choroidal regulation of oxygen supply to the guinea pig retina. In A. G. Hudetz, and D. F. Bruley (Eds.), Oxygen Transport to Tissue XX, pp. 385–389. Springer, 1998. doi:10.1007/978-1-4615-4863-8

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