Platelet Preservation

Cohen, Phin; Cooley, Mark H.; Gardner, Frank H.

doi:10.1056/nejm196510142731603

Cited by 31 publications

(5 citation statements)

References 10 publications

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“…This discrepancy would arise if labelled and unlabelled platelets differed in their reaction to injected heparin. However, there is no evidence to suggest that, except in the one to two hours immediately after infusion, labelled autologous platelets are distinguishable from other circulating platelets (Davey and Lander, 1964a), and it has been demonstrated that labelled platelets accurately reproduce the thrombocytopenic effects induced by such agents as adenosine diphosphate (Davey and Lander, 1964b), carbon particles, and bacterial endotoxin (Cohen, Braunwald, and Gardner, 1965). Therefore, had a real fall in circulating platelet levels occurred it should have been reflected in radioactivity measurements.…”

Section: Discussionmentioning

confidence: 99%

Effect of injected heparin on platelet levels in man

Davey

Lander

1968

J Clin Pathol

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SYNOPSIS Platelets from six normal subjects were labelled with radiochromate and reinfused into their donors. Subsequently, the effect of intravenously injected heparin upon the levels of circulating platelets and platelet radioactivity was studied. Although reductions in platelet counts occurred in three subjects following single injections of 10,000 units, these changes were not reflected in the levels of circulating platelet radioactivity. It is concluded that the alterations in platelet counts observed were probably due to an effect of heparin in vitro. The experimental evidence that heparin induces thrombocytopenia in vivo, in man, is unconvincing.

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Section: Discussionmentioning

confidence: 99%

Effect of injected heparin on platelet levels in man

Davey

Lander

1968

J Clin Pathol

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“…3 and 4 it can be seen that, at least for the case used, there are marked differences between the current at the outer and inner surfaces of the membrane. At the outer surface, the four models give comparable currents and show slightly sigmoid shape, while the inner surface current shows large differences initially between the models with a nearly exponential decay throughout.…”

mentioning

confidence: 90%

“…The Nernst-Planck equations (1) have been used extensively to describe electrolyte processes in membranes. While exact solutions to these equations for steady-state processes have been obtained (2), solutions of the time-dependent equations, which result from a perturbation of the system, have so far required some simplification to permit solution (3,4). In all of these cases, one tacit assumption is that the membrane is continuous, i.e., the diffusing ions can occupy any position along the path through the membrane.…”

mentioning

confidence: 99%

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Ion flow through a membrane: concentration and current responses to a step potential change.

Hays¹,

Buckwalter²,

Lin³

et al. 1978

Proc. Natl. Acad. Sci. U.S.A.

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Solutions of the simplified time-dependent Nernst-Planck electrodiffusion equations for various membrane models under the influence of a step voltage change are presented. Comparison of the results for a membrane with continuous sites to those for membranes with two, three, or five intermediate sites shows little difference either qualitatively or quantitatively in the concentration of the diffusible ion inside the membrane, although some quantitative differences are evident in the calculate currents. The Nernst-Planck equations (1) have been used extensively to describe electrolyte processes in membranes. While exact solutions to these equations for steady-state processes have been obtained (2), solutions of the time-dependent equations, which result from a perturbation of the system, have so far required some simplification to permit solution (3,4). In all of these cases, one tacit assumption is that the membrane is continuous, i.e., the diffusing ions can occupy any position along the path through the membrane. Such an assumption is inherent in the use of the Nernst-Planck equations.In this paper we present a comparison between the results expected from one simplified version of the Nernst-Planck equations in continuous form and the same simplified processes with the ion motion treated as a discrete, random walk process. The latter treatment has not been used extensively in this area and could prove important, especially in the treatment of thin membranes such as those found in biological systems. Continuous (macroscopic) model In the formulation of the problem, several simplifying assumptions were made. The diffusion coefficient (D), the electric mobility (U , and the electric field (E = -bV/bx) were all assumed to be independent of the position of the ion in the membrane. Inherent in the last assumption is that a pseudoneutrality exists, i.e., the Poisson term is treated as insignificant. The final constraint simplifying these equations is that the potential is a step function: V = Vo, t < 0. V = V, t > 0.[1A] [iB] With these assumptions, the Nernst-Planck equations be-

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“…He used Shockley's (1949) theory for p-n semiconductor junctions at equilibrium. Cohen and Cooley (1965) solved numerically the unsteady state problem with the electroneutrality approximation by taking the steady state solution as the point of departure. Hsueh and Newman (1970) the approach to limiting current.…”

Section: Introductionmentioning

confidence: 99%

Migration and Diffusion of Binary Electrolytes Under a Constant Current Ii

Lim

Franses

1983

Chemical Engineering Communications

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The problem in title is analyzed for dilute solutions with no substantial interionic effects and with the diffusivity and the electrophoretic mobility being related via the Nernst-Einstein equation. The case is considered of only the positive ion reacting at the electrodes, being produced at the anode and consumed at the cathode. With the electroneutrality condition as a first approximation, the equations for the average concentration and the electric field are decoupled and solved analytically. Then the deviation from electroneutrality is calculated in the second approximation via Poisson's equation. The problem has a steady state if the current is smaller than a certain value. With this analysis and measurements of concentrations at different times, electrophoretic mobilities of the two ions can be calculated. The implications for interpreting measurements in microelectrophoresis and electrophoretic mass transport analysis are discussed.

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Platelet Preservation

Cited by 31 publications

References 10 publications

Effect of injected heparin on platelet levels in man

Effect of injected heparin on platelet levels in man

Ion flow through a membrane: concentration and current responses to a step potential change.

Migration and Diffusion of Binary Electrolytes Under a Constant Current Ii

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