The role of Tamm-Horsfall mucoprotein in calcium oxalate crystallization. N-acetylcysteine--a new therapy for calcium oxalate urolithiasis.
OBJECTIVE
To assess the role of Tamm-Horsfall mucoprotein (THM), obtained from normal subjects (nTHM) and stone-formers (sfTHM), on crystallization of calcium oxalate (CaOx) in whole urine, and to assess the effects of N-acetylcysteine (AC) in preventing renal stone formation.


METHODS
A modified rapid evaporation method was used to test the effects of THM and AC on crystallization of CaOx in vitro. Animal experiments involving 30 rats and a clinical study involving 17 patients with idiopathic CaOx urolithiasis were also performed to identify further the role of AC in preventing CaOx stone formation in vivo.


RESULTS
The results showed that the volume of CaOx crystals was greatly reduced, by ultrafiltration, to 39.1% of untreated urine, but increased to 81.4% by adding nTHM (35 mg/l). sfTHM was a more potent promoter. AC was found to inhibit the transformation of THM and lower the crystallization of CaOx both in vitro and in vivo.


CONCLUSIONS
We believe that the transformation of THM is an important step in the formation of urolithiasis. AC might be a new way to prevent renal stone formation and recurrence.
Institute of Urology, Beijing Medical University, People's Republic of China.
J
J
Fan
S J
SJ
Shen
D000111:Acetylcysteine / Q000627:therapeutic use*; D000818:Animals; D002129:Calcium Oxalate / Q000378:metabolism*; D003460:Crystallization; D006801:Humans; D007668:Kidney / Q000378:metabolism; D007669:Kidney Calculi / Q000209:etiology* / Q000378:metabolism / Q000517:prevention & control; D008297:Male; D009088:Mucoproteins / Q000378:metabolism*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D014462:Ultrafiltration; D058949:Uromodulin
D009088:Mucoproteins; C548612:UMOD protein, human; D058949:Uromodulin; D002129:Calcium Oxalate; D000111:Acetylcysteine