[Detection of urinary organic acids by gradual titration of pH 2,0-7,4. Significance for the assessment of the litho-protective characteristic of the examined urine]. / Erfassung der organischen Säuren im Harn durch stufenweise Titrierung von pH 2,0--7,4. Bedeutung für die Abschätzung des lithoprotektiven Charakters des untersuchten Harns.

The role of organic acids in urine is not sufficiently known until today. From our detailed in vitro studies it can be concluded that some of them are highly efficacious in the inhibition of Ca-oxalate and Ca-phosphate crystal growth. Moreover, some of them showed, as acids and as salts, a strong lytic effect on stone-forming crystals and native stone-material. By the oral application to rats, concentrations preventing any precipitation out of meta- and instable Ca-oxalate solutions could be achieved. The renal excretion was controlled by the stepwise titration of preacidified urinary samples from pH 2.0 to 7.4 and the lithoprotective character of urine estimated by the Ca2+-binding capacity.

[In vitro and first in vivo experiments for the dissolution of calcium-containing urinary calculi (author's transl)]. / In-vitro- und erste In-vivo-Versuche zue Lyse calciumhaltiger Harnsteine.

There are numerous reports dealing with the significantly reduced citrate secretion in (recurrent) tone formers. The critical values of the Ca/citrate ratio in the nocturnal urine of (oxalate) stone formers has also been reported, emphasizing the need of medicaments being capable to increase the citrate secretion and to raise the basal citrate level of the nocturnal urine in these patients. In our in vitro experiments, we tested quantitatively the inhibitory activity of some new substances on crystal growth. In Wistar rats we measured the Ca2+-binding capacity as well as the citrate and oxalate excretion before and after oral application of a great number of new compounds. Some of them were highly efficacious in the reduction of the Ca-oxalate activity product, as can be derived from the increased Ca2+-binding capacity and/or the decreased oxalate secretion in urine.