Role of Agglomeration in the Early Stages of Papillar Stone Formation

Possible effects of crystal agglomeration on the early stages of calcium oxalate papillar stone formation are evaluated. The collecting ducts are filled with liquid that flows laminarly as established through hydrodynamical and physicochemical considerations. Under such conditions, agglomeration due to laminar shear forces proceeds. Agglomeration of calcium oxalate monohydrate crystals present in urine at a concentration typical for clinically observed crystalluria cannot result in the formation of a particle sufficiently large enough to be retained in the Bellini\u27s duct and become a papillar stone nidus (nucleus). Formation of such an aggregate during the passage time of urine through the duct requires an unrealistically high concentration of crystals in urine, one that exceeds the normal content of urinary oxalate by several orders of magnitude. Aggregates obstructing the Bellini\u27s duct as assumed in the free particle theory cannot represent a major factor in stone formation. This conclusion is corroborated by experimental results and other observations

An automatic system for crystal growth studies at constant supersaturation

An automatic system for growing crystals from seeded supersaturated solutions at constant supersaturation is described. Control of burettes and data acquisition are controlled by computer. The system was tested with a study of the calcium oxalate kinetics of crystal growth

Additional file 3: of Can Randall’s plug composed of calcium oxalate form via the free particle mechanism?

The transit time of particle through the tubule. (DOCX 13 kb

Phosphate composition of precipitates from urine-like liquors

The composition of the solid phases precipitating from urine-like liquors has been determined at 37°C over the pH range between 6 and 8 for solutions with varying amounts of magnesium, citrate, oxalate and ammonium ions. At pH □ 7 hydroxyapatite appeared, either alone or, depending on the magnesium ion concentration, in a mixture with brushite. Stravite and calcium phosphates precipitated at pH □ 7.5. No other phosphate solids were observed to precipitate from these urine-like liquors under physiological conditions. No influence on the nature of the solid phase was exerted by citrate, oxalate or ammonium ions. The variation of solid phase composition caused by changing solution composition is ascribed to kinetic rather than thermodynamic factors. Die Zusammensetzung von Phosphatphasen, die bei 37°C im pH-Bereich von 6 bis 8 aus künstlichem Urin auskristallisieren, wurde mit Hilfe analytischer und kristallographischer Methoden bestimmt. Die Löungen enthielten unterschiedliche Konzentrationen an Magnesium, Citrat, Oxalat und Amrnoniumionen. Je nach Magnesiumgehalt trat bei pH-Werten □ 7,0 Hydroxylapatit entweder allein oder gemeinsam mit Brushit auf. Struvit wurde gemeinsam mit Calciumphosphaten bei pH □ 7,5 festgestellt. Unter den vorherrschenden physiologischen Bedingungen konnte die Kristallisation anderer Phosphatphasen aus diesen kunstlichen Urinlösungen nicht nachgewiesen werden. Citrat, Oxalat und Ammoniumionen übten keinen Einfluß auf die Art der festen Phasen auf. Die Änderung der Zusamrnensetzung dieser festen Phasen mit sich ändernder Zusammensetzung der Lösung wird nicht thermodynamischen sondern kinetischen Faktoren zugeschrieben