Fragiligraphs

Abstract

Abstract 1,069,443. Measuring osmotic fragility of blood cells. A. TROMANS (YEDA RESEARCH & DEVELOPMENT CO.). April 17, 1964, No. 16084/64. Heading A5K. [Also in Divisions G1 and G2] The invention relates to an arrangement for determining the osmotic fragility of red blood cells. The method used involves suspending the cells in isotonic saline solution, gradually decreasing the concentration of the solution and determining the rate of hemolysis of the cells. The rate of hemolysis may be determined from the optical transmissivity of the sample. In one proposed apparatus the test cell consists of a plastic or metal frame 71 having a transverse aperture. Two channels 73, 74 extend upwards from the aperture and a dialysis tube 75 is stretched tightly over the aperture and the lower parts of the channels. A cell is thus constructed having windows 76, 77, on opposite sides formed by parts of the tube. A sample of blood in isotonic solution can be injected into the cell down one channel by means of a syringe, the other channel allows air to escape during filling. The charged cell is inserted, as indicated at 22 Fig. 1, into a transparent vessel 24 containing hypotonic solution or distilled water and a parallel light beam from a source 50 and collimator 52 directed through it. The light transmitted by the sample is passed to photoelectric detector 63. As the strength of the cell solution decreases with time due to osmosis the red blood cells swell and, in time, release hemoglobin thus varying the cell transmissivity. A transmissivity time curve may be plotted to assess the fragility of the cells but it is preferred to plot rate of change of transmissivity against time. For this purpose the detector output at the beginning of one unit of time may be stored as a potential across a capacitor, subtracted from the detector output on the end of the time period and the difference recorded. The detector output value at the end of the period then replaces the previously stored value as the initial output of the next time period. It is suggested that two second units of time would be suitable (Fig. 6 shows a block diagram of this arrangement). A filter passing light in the region of 50Á may be included in the light path.

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