Hypocitraturia as a risk factor for nephrocalcinosis after kidney transplantation

Calcium-oxalate crystal deposition in kidney transplant biopsy specimen led us to investigate the impact of calcineurin inhibitor treatment on urinary excretion of lithogenic and stone inhibitory substances in 53 children after successful kidney transplantation (KTx) receiving cyclosporine A (CsA) or tacrolimus. We compared the values obtained with those of 12 patients with recurrent nephrotic syndrome under CsA and of 6 patients with Rasmussen encephalitis (RE) under tacrolimus therapy. Renal ultrasound examinations were repeatedly performed. Hypocitraturia was found in 69% of patients, with KTx patients having a significantly lower urinary citrate excretion than those receiving calcineurin inhibitors for other reasons. Secondly, we found hyperoxaluria in 35% of patients, again especially in those after KTx. No significant difference in urinary substances was seen comparing CsA with tacrolimus treatment. Urolithiasis was found in one and calcium-oxalate crystal deposition in biopsy specimen of three KTx patients. Calcineurin inhibitor treatment can lead to significant hypocitraturia, especially in patients after KTx receiving the highest dose of medication. Hyperoxaluria is primarily the result of a removal of significant body oxalate stores, deposited during dialysis, but may not be suspected as a specific side effect of calcineurin inhibitor therapy. Both findings can increase the risk for urolithiasis or nephrocalcinosis.     

Partial hypoxanthine-guanine phosphoribosyltransferase deficiency presenting as acute renal failure

Hyperuricemia and secondary urate nephropathy are uncommon in the paediatric setting outside of tumour lysis syndrome. We describe the case of a 12-year-old boy who presented at 3 years of age with acute renal failure. The cause of this remained unknown until the development of uric acid renal calculi 9 years later. This, and the availability of the previously unknown family history, provided the subsequent diagnosis of partial hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency. Detailed family history is important for early detection of this heterogeneous group of disorders. Early treatment may minimise long-term renal morbidity and mortality from renal insufficiency.     

Vitamin B6 metabolites in idiopathic calcium stone formers: no evidence for a link to hyperoxaluria

Vitamin B6 metabolites and their potential correlates to urinary oxalate excretion in idiopathic calcium stone formers (ICSF) compared with healthy subjects were investigated. This clinical study was performed in a population of male ICSF with (Hyperoxalurics, n=55) or without hyperoxaluria (Normooxalurics, n=57) as well as in 100 healthy male control subjects. Pyridoxal 5-phosphate serum concentration (S-pyridoxal 5P) and 24-h urinary excretion of 4-pyridoxic acid (U-4pyridoxic acid) were measured using HPLC; 24-h urinary excretion of oxalate (U-oxalate) was measured concurrently. A subgroup of subjects (40 Hyperoxalurics, 15 Normooxalurics and 50 controls) underwent the same measurements before and after 7-day pyridoxine loading per os (pyridoxine hydrochloride, 300 mg/d). Under usual conditions, U-4pyridoxic acid was similar in the three groups, whereas mean S-pyridoxal 5P was significantly lower (p<0.0001) in the Hyperoxalurics (59.6±21.2 nmol/L) and in the Normooxalurics (64.9±19.7 nmol/L) than in the controls (86.0±31.0 nmol/L). No correlation could be found between U-oxalate and U-4pyridoxic acid or S-pyridoxal 5P. After B6 loading, S-pyridoxal 5P was still significantly lower in the Hyperoxalurics (415±180 nmol/L, p<0.001) and in the Normooxalurics (429±115 nmol/L, p=0.036) than in the controls (546±180 nmol/L), although there was no difference between groups for U-4pyridoxic acid. No correlation in any group could be found between changes in U-oxalate and changes in U-4pyridoxic acid or S-pyridoxal 5P. Although there is no vitamin B6 deficiency in ICSF with or without hyperoxaluria, these patients, on average, have lower levels of S-pyridoxal 5P than healthy subjects. However, this slight decrease does not seem to account for idiopathic hyperoxaluria.     

The effect of ions at the surface of calcium oxalate monohydrate crystals on cell-crystal interactions

Magnesium is an abundant ion in biologic systems, including renal tubular fluid; however, the precise role of magnesium during the interaction of calcium oxalate crystals with cells has not been previously defined. In addition, the respective roles of calcium and hydrogen ions during the cell-crystal bonding interaction remain poorly defined. Here we report an atomic level three-dimensional study of a single crystal of calcium oxalate monohydrate (COM; whewellite) which was bathed in a solution of magnesium hexahydrate for 1 year. Magnesium was not incorporated into the structure of whewellite to any significant degree. Instead, COM accepted magnesium primarily as an adsorbate in a binding configuration which, as a surface phenomenon, is controlled by localized charge effects. The effect of magnesium and calcium on the efficiency of calcium oxalate crystal binding to renal cells was also investigated. When present in supraphysiologic concentrations (greater than 0.1 M), magnesium progressively inhibited adhesion of pre-formed COM crystals to cultured renal cells. Therefore, even though magnesium does not incorporate into the crystal structure of calcium oxalate, magnesium can exert important surface effects and change the interaction of pre-formed COM with molecules anchored on the cell surface. Similarly, binding was nearly blocked when the exogenous calcium concentration was > or =0.1 M (supraphysiologic range), although in lower concentrations (within the physiologic range) exogenous calcium promoted crystal adhesion. Finally, the ambient hydrogen ion concentration also influenced calcium oxalate crystal interactions with renal cells, with maximal binding occurring at a pH of 4. Therefore, hypercalciuria and/or an acidic urine could each promote renal stone formation via increased crystal adhesion to renal cells, a previously under-appreciated potential mechanism.     

Ceftriaxone-associated nephrolithiasis and biliary pseudolithiasis in a child

Ceftriaxone is a widely used third-generation cephalosporin. It is generally very safe, but complications of biliary pseudolithiasis and, rarely, nephrolithiasis have been reported in children. These complications generally resolve spontaneously with cessation of the ceftriaxone therapy; however, they may symptomatically mimic more serious clinical problems, such as cholecystitis. We report a case of both ceftriaxone-induced biliary pseudolithiasis and nephrolithiasis.     

Characterization of uronic-acid-rich inhibitor of calcium oxalate crystallization isolated from rat urine

Human urine contains several macromolecules which inhibit calcium oxalate crystallization. Uronic-acid-rich protein (UAP), a glycoprotein with a molecular weight of approximately 35 kDa, is one such inhibitor. Here we report the characterization of UAP extracted from rat urine using three chromatographic steps including diethylaminoethanol (DEAE)-Sephacel, Sephacryl S-300 and Mono Q column and compare it with human UAP. The molecular weight of rat UAP (UAP_r) is similar to that of human UAP (UAP_h), being approximately 35 kDa as estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Their amino acid compositions are identical, they contain a high percentage of aspartic and glutamic acids and they react positively in the carbazole reaction, suggesting that they contain uronic acid. The inhibitory activities of UAP_h and UAP_r were assayed on a calcium oxalate crystallization system in vitro using [⁴⁵Ca]calcium chloride. Both exert a strong inhibition, suggesting that UAP_r, like UAP_h, plays an important role in preventing and reducing calcium oxalate crystallization in the urine. On Western blot analysis, both UAP_h and UAP_r immunoreact with inter--trypsin inhibitor (ITI) antibody. Nevertheless, using the Ouchterlony immunodiffusion technique, there was no precipitation line between ITI antibody and UAP. Therefore, we hypothesize that UAP is related to ITI and that they may have the same epitope but are not completely identical. We conclude that UAP belongs to the ITI superfamily of macromolecules which contribute to the regulation of the calcium oxalate crystallization process.     

Pharmacological and toxicological effects of Paronychia argentea in experimental calcium oxalate nephrolithiasis in rats

Aim of the study

Renal protection and antiurolithiasic effects of two extracts of Paronychia argentea (PA), a traditional Algerian plant commonly known as Algerian tea, were evaluated. This study was carried out to determine whether the aqueous extract (APA) or the butanolic extract (BPA) of aerial parts could prevent or reduce calculi aggregation in experimental calcium oxalate (Ox) nephrolithiasis in Wistar rats.

Materials and methods

The two extracts (APA and BPA) were administrated orally and daily, during 28 days to nephrolithiasic treated rats at the dose of 250, 500 mg/kg b.w. and 10, 20 mg/kg b.w. respectively.Body weight, renal index, liver index, serum level of creatinine, uric acid, urea, K⁺, Ca²⁺, Mg²⁺, Na⁺ and transaminase (alanine aminotransferase, ALT; aspartate aminotransferase, AST), phosphatase alkaline activity (PAL) were evaluated following the 28 days treatment in rats. In addition histopathological changes in kidney and liver were stained in hematoxylin eosin (HE).

Results

The effect of the extracts could be advantageous in preventing urinary stone retention by reducing renal necrosis and thus inhibit crystal retention. In contradiction with APA, the two doses of BPA attenuated elevation in the serum creatinine (p < 0.01) and blood urea levels (p < 0.01) (nephroprotective effect). However, the increase in ALT (27%) and PAL (31–51%) serum levels and in the relative liver weights (p < 0.01) in the groups treated with doses of APA may indicate that this extract has not a hepatoprotective effect against oxalate toxicity.

Conclusions

The presented data indicate that administration of the butanolic extract of aerial parts to rats with NaOx induced lithiasis, and reduced and prevented the growth of urinary stones in experimental calcium oxalate nephrolithiasis in Wistar rats.     

膀胱内腹腔镜下输尿管膀胱再吻合术五例报告

目的 探讨后腹腔镜下肾窦内肾盂切开取石治疗肾鹿角状及多发性结石的疗效. 方法肾多发及鹿角状结石患者15例.男9例,女6例.平均年龄40岁.结石直经1.5～3.7 cm.常规用3个穿刺器,建立气腹于腹膜后间隙,紧贴肾盂外膜向肾窦内分离,暴露出肾盏漏斗部,切开取石,输尿管内置入双J管,3-0可吸收线缝合肾盂切口.冲洗、放置引流管.术后3～4 d拔出引流管.2周左右拔出双J管. 结果 15例手术均获成功,平均手术时间170 rain.术后平均住院7 d.随访3～15个月,2例有0.2～0.5 cm结石残留. 结论 后腹腔镜下肾窦内肾盂切开取石提供了微创的新途径,暴露好、出血少、创伤小、恢复快.     

A novel SOX9 mutation, 972delC, causes 46,XY sex-reversed campomelic dysplasia with nephrocalcinosis, urolithiasis, and dysgerminoma

An 8-year-old phenotypic female with campomelic dysplasia (CD) and 46,XY sex-reversal presented with renal colic. Medullary nephrocalcinosis, urolithiasis, and renal malrotation were diagnosed by computed tomographic scanning. Pelvic sonogram identified an enlarged left gonad. Genetic testing revealed a novel SOX9 heterozygous deletion of a cytosine at nucleotide 972 (972delC), causing a frameshift at codon 200, introducing a stop codon 18 codons further downstream (P200fsX218). At laparoscopic gonadectomy, a left dysgerminoma was removed. This first reported case of dysgerminoma in a sex-reversed patient with CD who also had urolithiasis stresses the importance of prophylactic gonadectomy and urologic evaluations in this susceptible population.     

Postoperative Bildgebung in der Uroradiologie

Zusammenfassung Die Behandungsstrategien und Operationstechniken urologischer Erkrankungen unterliegen einer ständigen Fortentwicklung. Die Therapieschemata und operativen Eingriffe werden zunehmend differenzierter und komplexer. Für den uro-radiologisch tätigen Radiologen ist es deshalb unerläßlich, sich mit Therapie und OP-Techniken zu befassen, um postoperative Befunde werten und einordnen zu können. Im ersten Teil der Übersicht werden aktuelle Therapie und postoperative Bildgebung bei Nephrolithiasis, bei Nierentumoren und bei Erkrankungen der Ureteren abgehandelt. Die Auswahl der geeigneten Untersuchungsmodalität und der sinnvolle Einsatz der Bildgebung im zeitlichen Zusammenhang mit dem Eingriff werden dargelegt. Besonderer Wert wird auf die Darstellung jeweils typischer postoperativer Befunde gelegt. Die Abklärung eingiffsspezifischer Komplikationen und ihr radiologisches Bild werden geschildert.

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