Male hypercalciuric stone formers with low renal calcium reabsorption

Therapy of calcium oxalate urolithiasis in a rhesus macaque (Macaca mulatta)

A rhesus macaque (Macaca mulatta) was presented for anuria. Examination revealed calcium oxalate concrements in the bladder. A cystotomy was performed, and a therapy with alfuzosin was conducted. Over 1 year after the treatment, the rhesus macaque had not shown any more signs of stranguria. This is the first case reporting the successful treatment of urolithiasis in a rhesus macaque.

The Wnt11 Signaling Pathway in Potential Cellular EMT and Osteochondral Differentiation Progression in Nephrolithiasis Formation

The molecular events leading to nephrolithiasis are extremely complex. Previous studies demonstrated that calcium and transforming growth factor-β1 (TGF-β1) may participate in the pathogenesis of stone formation, but the explicit mechanism has not been defined. Using a self-created genetic hypercalciuric stone-forming (GHS) rat model, we observed that the increased level of serous/uric TGF-β1 and elevated intracellular calcium in primary renal tubular epithelial cells (PRECs) was associated with nephrolithiasis progression in vivo. In the setting of high calcium plus high TGF-β1 in vitro, PRECs showed great potential epithelial to mesenchymal transition (EMT) progression and osteochondral differentiation properties, representing the multifarious increased mesenchymal and osteochondral phenotypes (Zeb1, Snail1, Col2A1, OPN, Sox9, Runx2) and decreased epithelial phenotypes (E-cadherin, CK19) bythe detection of mRNAs and corresponding proteins. Moreover, TGF-β-dependent Wnt11 knockdown and L-type Ca²⁺ channel blocker could greatly reverse EMT progression and osteochondral differentiation in PRECs. TGF-β1 alone could effectively promote EMT, but it had no effect on osteochondral differentiation in NRK cells (Rat kidney epithelial cell line). Stimulation with Ca²⁺ alone did not accelerate differentiation of NRK. Co-incubation of extracellular Ca²⁺ and TGF-β1 synergistically promotes EMT and osteochondral differentiation in NRK control cells. Our data supplied a novel view that the pathogenesis of calcium stone development may be associated with synergic effects of TGF-β1 and Ca²⁺, which promote EMT and osteochondral differentiation via Wnt11 and the L-type calcium channel.

Characterisation of risk factors for stones in hyperuricosuric men attending a stone clinic

Hyperuricosuria is common among stone formers, but its significance is uncertain. To progress our understanding and target treatment, we need to identify and characterise patients with uniform underlying pathology. We aimed to identify hyperuricosuric patients with a primary defect in renal urate reabsorption (renal hyperuricosuria) and to look for associated risk factors for stones. We undertook a retrospective cross-sectional database study of 666 male stone formers attending the Southampton stone clinic. We estimated filtered urate from plasma urate and 24-h creatinine clearance, and the net percentage reabsorbed. 153 men had hyperuricosuria (urine urate >4.80 mmol/24 h); 513 had normouricosuria. Hyperuricosuric men filtered more urate (median 68.1 and 52.5 mmol/24 h) but the ranges overlapped. Thirty hyperuricosuric men with filtered urate below the median for normouricosuria were selected as the renal hyperuricosuria group. Their normal plasma urate and high urate clearance substantiated this classification. In comparison with 60 normouricosuric stone formers matched for filtration, they had a higher incidence of hypercalciuria (67 versus 40%), but similar, high, frequencies of hyperoxaluria (25 and 11%) and phosphaturia (40 and 27%).There were no differences in age at first stone, incidence of stone recurrence or positive family history (20 and 25%). The findings demonstrate multiple risk factors for stones in this subgroup. In comparison, the 30 hyperuricosuric men with the highest filtration had a higher incidence of hyperoxaluria (58%) but fewer (7%) had a positive family history. Creatinine clearance was raised in 73%. An excessive protein intake might be a major correctable factor underlying these abnormalities.