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Biomedical subjects

H Osada

Publications and source records attributed to H Osada.

At least 307 records · Page 17Linked to original sources
PubMed1982

Pulse sequences generated by a degenerate analog neuron model.

The response characteristics of an electronic neuron model proposed by the authors are investigated. Periodic stimulating pulse sequences with a fixed frequency are applied to the analog neuron model and the response pulse sequences are studied. In the degenerate case, the state transition of the neuron model during one period of the stimulating pulse sequense is described by a first order piecewise linear difference equation with a jump. It is shown that the periodic response pulse sequences of the neuron model belong to a special class of pulse sequences generated by a simple algorithm, and that the relation between the pulse width (or amplitude) of the stimulating pulse and the firing rate of the neuron model takes the form of an extended Cantor function.

Animals↗
PubMed1982

Simultaneous fluorometry of urinary dopamine, norepinephrine, and epinephrine compared with liquid chromatography with electrochemical detection.

A simple fluorometric method is described for simultaneous assay of urinary norepinephrine, epinephrine, and dopamine. The catecholamines are separated by boric acid gel chromatography and subsequently determined by use of a modified trihydroxyindole reaction. By the separation with boric acid gel, dopa can be eliminated, which interferes with dopamine measurement; consequently, the reaction is specific for catecholamines. This simple, rapid method was applied to urine specimens from normal adults. Values for urinary dopamine, norepinephrine, and epinephrine agreed with those obtained by "high-performance" liquid chromatography with electrochemical detection.

Adolescent↗
PubMed1979

Biocompatibility of standard and silica-free silicone rubber membrane oxygenators.

Spiral coil membrane oxygenators made from either standard silicone rubber or silica-free silicone rubber were compared using three priming techniques. Standard priming, carbon dioxide priming, and denucleation priming were employed with each type of device. Four-hour venovenous membrane oxygenator perfusions were carried out on awake sheep anticoagulated with heparin. Virtually no differences were observed in any parameters measured between standard silicone rubber and filler-free silicone rubber membranes. Significantly greater platelet losses occurred during the first hour of perfusion with standard priming and with carbon dioxide priming than with denucleation priming, using either type of membrane. These experiments demonstrate that denucleation priming reduces platelet losses during extracorporeal membrane oxygenator perfusion, but that the use of filler-free silicone rubber does not improve the biocompatibility of the membrane.

Animals↗
PubMed1979

A note on the representation of the performance of hemodialyzers.

The performance of hemodialyzers was expressed schematically using three dimensionless quantities. Compared with the usual representation in which the dialysance is plotted against the blood flow rate for each of the solutes of interest, this expression is considered to have the following advantages: (1) the function of a dialyzer to remove different solutes can be expressed by a single curve, (2) the effect of changing the membrane area, its permeability, and the flow rates on the performance can easily be understood, and (3) the effect of changing the blood flow rate on the ratio of the transport efficiency of two or more kinds of solutes can be evaluated. An estimate of the overall mass transfer coefficient is the only procedure necessary to move from the usual to the present expression. These analyses were applied to the performance of a commercial hemodialyzer, and it was verified that this representation could denote its operation fairly well.

Blood Flow Velocity↗