[Studies on infection urolithiasis--urease induced crystallization in synthetic urine]

In the present study, urease induced crystallization in synthetic urine was studied by an aggregometer technique.

The synthetic urine was made by the method by Griffith et al (1976). The synthetic urine of 200 microliters portions were stirred constantly at 37 degrees C, and then 10 microliters of urease solution (1000 U/ml) was added. An aggregometer were recorded as turbidity curves on a chart during the incubation for the crystallization simultaneously.

A two-phase turbidity curve was obtained from the reaction of synthetic urine and urease. Firstly the mild turbidity appeared gradually up until to approximately 13 min, and then the turbidity increased rapidly. The mild turbidity was called "early crystallization" and the rapid turbidity was called "late crystallization". The early crystallization appeared gradually at pH 7.3 and 0.05 M of anmmonia concentration, and this amount was completely depended on the concentration of calcium in the synthetic urine. The late crystallization occurred rapidly at pH 8.5 and 0.06-0.08 M of anmmonia concentration and this amount was completely depended on the concentration of magnesium in the synthetic urine. We confirmed the early crystallization as calcium phosphate and the late crystallization as magnesium ammonium phosphate by the observations of polarized light microscopy as well as the estimations using an infrared spectrometer.

Urease induced crystallizations in the synthetic urine had a two-phase turbidity. Firstly the mild turbidity of calcium phosphate appeared gradually, and then rapid turbidity of magnesium ammonium phosphate occurred. Therefore, it is suggested that various crystallizations may be developed in the infected human urine according to the constituents of calcium and magnesium.