2026-06-14T03:44:41Zhttps://repisalud.isciii.es/rest/oai/request

oai:repisalud.isciii.es:20.500.12105/204542024-11-28T19:35:37Zcom_20.500.12105_15322com_20.500.12105_2051col_20.500.12105_16967

00925njm 22002777a 4500 dc Grases, F author Sohnel, O author 2017-09-08 Background: The likelihood of a Randall's plug composed of calcium oxalate monohydrate (COM) forming by the free particle mechanism in a model of kidney with a structure recently described by Robertson was examined at the most favourable conditions for the considered mechanism. Methods: The Robertson model of the kidney is used in the following development. The classical theory of crystallization was used for calculations. Results: Initial COM nuclei were assumed to form at the beginning of the ascending loop of Henle where the supersaturation with respect to COM has been shown to reach the threshold level for spontaneous nucleation. Nucleation proceeds by a heterogeneous mechanism. The formed particles are transported in the nephron by a laminar flow of liquid with a parabolic velocity profile. Particles travel with a velocity dependent on their position in the cross-section of the nephron assumed to be straight tubule with smooth walls and without any sharp bends and kinks. These particles move faster with time as they grow as a result of being surrounded by the supersaturated liquid. Individual COM particles (crystals) can reach maximum diameter of 5.2 x 10(-6) m, i.e. 5.2 mu m, at the opening of the CD and would thus always be washed out of the CD into the calyx regardless of the orientation of the CD. Agglomeration of COM crystals forms a wractal object with an apparent density lower than the density of solid COM. The agglomerate that can block the beginning of the CD is composed of more crystals than are available even during crystaluria. Moreover the settling velocity of agglomerate blocking the opening of the CD is lower than the liquid flow and thus such agglomerate would be washed out even from upward-draining CD. Conclusions: The free particle mechanismmay be responsible for the formation of a Randall's plug composed by COM only in specific infrequent cases such as an abnormal structure of kidney. Majority of incidences of Randall's plug development by COM are caused by mechanism different from the free particle mechanism. Grases F, Sohnel O. Can Randall's plug composed of calcium oxalate form via the free particle mechanism?. BMC Urol. 2017 Sep 08;17:80. 10.1186/s12894-017-0274-7 1471-2490 BMC Urology http://hdl.handle.net/20.500.13003/9648 28886706 L618198658 2-s2.0-85029120798 http://hdl.handle.net/20.500.12105/20454 409965000001 Randall's Plug Calcium oxalate monohydrate Formation mechanism Can Randall's plug composed of calcium oxalate form via the free particle mechanism?