Erythrocyte destruction in different types of Starr-Edwards aortic ball valves

Increased destruction of red blood cells follows the insertion of ball valves into the heart in most cases. Usually, hemolysis is slight, but in some patients uncompensated hemolytic anemia develops. To study the influence on hemolysis of the mechanical properties of the prostheses, the degree of erythrocyte destruction was evaluated in patients with Starr-Edwards aortic prostheses of different types and size.

Fifty-six patients with Starr-Edwards aortic ball valves were examined; 13 had prostheses of the 1200 series with silastic rubber balls, and 43 had valves of the 2300 series with hollow Stellite (metallic) balls. Thirty-one patients had valves with an orifice area of 1.8 cm 2 or less; the others had larger-sized valves.

The degree of hemolysis was predicted from the serum lactic dehydrogenase activity, which has previously been shown to correlate well with the red blood cell survival. The half-life of 51 Cr-labelled red cells was also determined in 16 cases.

Hemolysis was significantly higher in patients with Stellite ball valves than in those with silastic rubber ball valves, and red blood cell destruction was more pronounced in patients with small prostheses than in patients with larger valves. Hemolysis was not higher in three patients with paravalvular leakage than in patients with competent prostheses. Valve type and size seem to be the most important factors in producing hemolysis.

Convenient microscopic tests for yeast viability and sporogenic capability

Drops of cell suspension are seeded on nutrient medium containing 5% purified agar and spread between the agar surface and a cover glass. The liquid phase is absorbed by the concentrated agar, so that the cells are held in situ between glass and agar. After incubation nongerminated cells and micro-colonies are counted microscopically. Sporogenic capability is assessed by seeding very dense cell suspensions on acetate agar and covering with Teflon F.E.P. membrane which is permeable to oxygen.

Droplet countercurrent chromatography

A new form of countercurrent chromatography, named droplet counter-current chromatography, has been developed. This all-liquid separation technique is based on the partitioning of solute between a steady stream of droplets of moving phase and a column of surrounding stationary liquid phase. Milligram quantities of dinitrophenyl (DNP) amino acids were separated with an efficiency comparable to that of gas chromatography.