A novel apparatus for measuring the velocity of platelet aggregation, with TV image processing.

We have made an apparatus(With Software)for the quantitative measurement of platelet aggregation and adhesion.1。The principles of operation are as follows.(1)The reaction chamber is composed of a rotating cone(Variable Speed)and a plate(e.g.，polymethylmethacrylate)，and the platelets(Mixed With ADP Or Adrenaline)are poured into the gap between the cone and the plate，in order to give a certain shear rate。(2)The microscopic TV images are separated into two images using a TV image processor：one is the averaged image(Of Consecutive8TV Pictures)in which the stationary spots of the adhered platelets are intensified；the other is the image of the moving spots of the flowing platelets which is obtained by subtracting the averaged image from the next TV picture.(3)These images are digtized(1bit)at a certain grey level，then encoded to the number and the total area of the spots in a frame(real dimension of 190x150&lt；micro&gt；m)using a TV image analyzer。(4)Above processes(2and3)are repeated at an interval of 5sec，and finally the time courses are displayed：e.g.，total area of the adhered spots vs.time，total area/spot of the flowing spots vs.time，etc.(5)The size histograms of the observed spots are obtained with another program.2。The appropriate experimental conditions for human platelet rich plasma are established：i.e.，1-3/s of shear rate，80-200x1000/&lt；micro&gt；l of platelets，0.2-0.5&lt；micro&gt；M ADP or1-5&lt；micro&gt；M adrenaline，at 25°C.3。The observed time courses of platelet adhesion are successfully simulated by the calculation based on a simple kinetic model，with three rate constants：it is proved that the growth rate of adhered spots is faster than that of de nove adhesion onto the free surface。

We have made an apparatus (with software) for the quantitative measurement of platelet aggregation and adhesion.1. The principles of operation are as follows. (1) The reaction chamber is composed of a rotating cone (variable speed) and a plate (e.g., polymethylmethacrylate), and the platelets (mixed with ADP or adrenaline) are poured into the gap between the cone and the plate, in order to give a certain shear rate. (2) The microscopic TV images are separated into two images using a TV image processor: one is the averaged image (of consecutive 8 TV pictures) in which the stationary spots of the adhered platelets are intensified; the other is the image of the moving spots of the flowing platelets which is obtained by subtracting the averaged image from the next TV picture. (3) These images are digtized (1 bit) at a certain grey level, then encoded to the number and the total area of the spots in a frame(real dimension of 190 x 150 <micro> m) using a TV image analyzer. (4) Above processes (2 and 3) are repeated at an interval of 5 sec, and finally the time courses are displayed: e.g., total area of the adhered spots vs. time, total area/spot of the flowing spots vs. time, etc. (5) The size histograms of the observed spots are obtained with another program.2. The appropriate experimental conditions for human platelet rich plasma are established: i.e., 1 - 3 /s of shear rate, 80 - 200 x 1000 / <micro> l of platelets, 0.2 - 0.5 <micro> M ADP or 1 - 5 <micro> M adrenaline, at 25゜C.3. The observed time courses of platelet adhesion are successfully simulated by the calculation based on a simple kinetic model, with three rate constants: it is proved that the growth rate of adhered spots is faster than that of de nove adhesion onto the free surface.