Ferrography, a magnetic separation method first developed for industrial sample analyses, has been modefied for application to biological analyses. Separation and quantitation of bacteria in the presence of paramagnetic trivalent metalion, erbium, using modified Ferrography, termed‘ Bactography’, was evaluated to quantitate bacterial concentrations in solutions in the clinical range of interest. Escherichia coli(E.coli)was used as a model bacterial system to optimize the separation protocol. Separation results were evaluated quantitatively by both light scattering and direct cell counting. The modified separation protocol with a newly designed sample processor and magnetic assembly provided higher cell deposition than the previous protocol. The modified protocol and direct cell counting allowed reliable detection and enumeration of concentrations of bacterial suspension of E.coli at105CFU/ml which is of significance in clinical diagnostic applications. Bactography offers promise as a method for quantitation of bacterial solutions.

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To decide the weaning time from the left ventricular assist deivce(LVAD)without exposing patients todanger by stopping the LVAD temporally, we have proposed a cardiac function estimation method underpump-on condition. In the atrio-aortic bypass, interference between the left ventricle and the LVAD mayoccur, because they pump blood in parallel: i. e., hemodynamics can fluctuate according to the change inthe delay time in a synchronous pumping. Both a computer simulation and the animal experiments showedthat the degree of the hemodynamic fluctuation, especially in pump flow, was smaller in the damaged heartthan in the intact one. The hemodynamics after pump-off may be estimated from the degree of the fluctutaion. In this report, the authors analyzed the effect of parameter variation on the fluctuation in pump flow usinga computer simulation, and found that the systemic compliance, the heart rate, the blood volume, and thesystemic resistance have marked effect on the degree of the fluctuation in pump flow.

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