Masao Tsujihata

Mechanism of calcium oxalate renal stone formation and renal tubular cell injury

Abstract:  Formation of calcium oxalate stones tends to increase with age and begins from the attachment of a crystal formed in the cavity of renal tubules to the surface of renal tubular epithelial cells. Though most of the crystals formed in the cavity of renal tubules are discharged as is in the urine, in healthy people, crystals that attach to the surface of renal tubular epithelial cells are thought to be digested by macrophages and/or lysosomes inside of cells. However, in individuals with hyperoxaluria or crystal urine, renal tubular cells are injured and crystals easily become attached to them. Various factors are thought to be involved in renal tubular cell injury. Crystals attached to the surface of renal tubular cells are taken into the cells (crystal–cell interaction). And then the crystal and crystal aggregates grow, and finally a stone is formed.

Laparoscopic Radical Nephroureterectomy: A Multicenter Analysis in Japan

BACKGROUND Laparoscopic nephroureterectomy (LNUx) is prevalent in Japan and throughout the world, but long-term outcome data remain limited. OBJECTIVE To understand the present state of LNUx in Japan, we conducted a multicenter analysis of clinical outcome and long-term cancer control for patients who underwent the procedure. DESIGN, SETTING, AND PARTICIPANTS Between January 1995 and December 2005, 1003 patients with urothelial cancer in the upper urinary tract were treated with LNUx at 51 institutions in Japan, and patient data were collected retrospectively. MEASUREMENTS Patient profiles were gathered and analyzed for survival, intravesical recurrence, and risk factors influencing them. RESULTS AND LIMITATIONS Median operative time was 320 min. Median bleeding volume was 232 ml. Complications occurred in 93 cases (9.3%) intraoperatively and in 107 cases (10.7%) postoperatively. Overall survival rate was 70% at 5 yr. Grade 3, pT3 or pT4, multifocal tumor, lymph-node metastasis, and previous or coexistent bladder tumor were independent risk factors for overall survival. Intravesical recurrence rate was 43% at 5 yr. Intravesical recurrence occurred more frequently in males, in patients with multifocal tumors, in patients with previous or coexistent bladder tumors, and in patients who underwent the hand-assisted approach. CONCLUSIONS Our report represents the largest multicenter analysis of LNUx reported to date. Male sex and the use of the hand-assisted approach were shown for the first time to be risk factors for recurrence-free survival and intravesical recurrence. To further analyze the effectiveness of LNUx, a long-term outcome comparison with risk stratification must be made between LNUx and open nephroureterectomy.

FIBRONECTIN AS A POTENT INHIBITOR OF CALCIUM OXALATE UROLITHIASIS

PURPOSE Fibronectin (230 kD.) is a multifunctional alpha2-glycoprotein distributed throughout the extracellular matrix and body fluids. Many investigators have demonstrated that fibronectin, because of its cell adhesive action, is related to biological processes such as morphogenesis, wound healing and metastasis. Recent studies have shown that a variety of molecules, including fibronectin, inhibit endocytosis of calcium oxalate crystals in vitro. We investigated other roles of fibronectin in calcium oxalate stone formation. MATERIALS AND METHODS Immunoblotting of the crystal surface binding substance obtained from pooled healthy male urine samples was used to analyze whether fibronectin was adsorbed onto the surface of calcium oxalate crystals. To clarify the relationship between fibronectin and calcium oxalate crystals, we performed 6 experiments. Experiment 1 was immunohistochemical examination of fibronectin expression in stone forming rat model kidneys, and experiment 2 examined the fibronectin content of stone forming rat kidney models with the enzyme-linked immunosorbent assay. Experiment 3 was designed to determine fibronectin content of Madin-Darby canine kidney (MDCK) cells stimulated by addition of calcium oxalate crystals and experiment 4 identified the inhibitory effect of fibronectin on calcium oxalate crystal growth by the seed crystal method. For experiment 5 we used an aggregometer system to clarify the inhibitory effect of fibronectin on calcium oxalate crystal aggregation and experiment 6 examined the inhibitory effect of fibronectin on the adhesion of calcium oxalate crystals to MDCK cells. RESULTS In the crystal surface binding substance immunoreactive bands at 230 kD., which correspond to the molecular weight of fibronectin, were detected by Western blot analysis. In stone forming rat kidneys strong expression of fibronectin was found on the renal tubules to which the crystals were attached. The fibronectin content of these kidneys was significantly greater than that of kidneys without calcium oxalate crystals. The fibronectin content of MDCK cells tended to increase in proportion to the concentration of calcium oxalate crystals added to the culture medium. The growth inhibition assay showed that the inhibitory effect of fibronectin on calcium oxalate crystal growth was small in relation to the quantity of fibronectin excreted. However, fibronectin had inhibitory effects on calcium oxalate crystal aggregation and adhesion of the crystals to MDCK cells. CONCLUSIONS Fibronectin secretion can be stimulated by calcium oxalate crystals, and this protein, which is excreted from the tubular cells, may inhibit calcium oxalate crystal aggregation and attachment to cells.

Atorvastatin Inhibits Renal Crystal Retention in a Rat Stone Forming Model

PURPOSE The interactions between crystals and renal tubular cells are important factors in urolithiasis formation. Moreover, some reports have suggested the involvement of renal tubular cell injury in crystal-cell interaction processes. Atorvastatin, which is a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A, is prescribed to decrease high cholesterol levels, and it has anti-inflammation and anti-oxidization activities. Atorvastatin is also reported to control transforming growth factor-beta1 expression. We investigated whether atorvastatin can prevent renal tubular cell injury by oxalate and inhibit renal crystal retention. MATERIALS AND METHODS Ten-week-old specific pathogen-free male Sprague-Dawley rats were used. Atorvastatin (2 mg/kg) in 0.5% carboxymethyl cellulose was administered orally daily for 2 weeks. The rats were separated into 4 experimental groups, including group 1--water and 0.5% carboxymethyl cellulose daily, group 2--water and atorvastatin in 0.5% carboxymethyl cellulose daily, group 3--1% ethylene glycol dissolved in water, 0.5 mug vitamin D3 dissolved in 1 ml salad oil and 0.5% carboxymethyl cellulose daily, and group 4--1% ethylene glycol dissolved in water, 0.5 microg vitamin D3 dissolved in 1 ml salad oil and atorvastatin in 0.5% carboxymethyl cellulose daily. The ethylene glycol model of hyperoxaluria and the effect of atorvastatin treatment were analyzed in groups 1 to 4. Urine samples were collected every 24 hours in metabolic cages and analyzed immediately or stored at -70C until analysis. The rats were sacrificed after 2 weeks and the kidneys were removed for further examination. We measured urinary N-acetyl glucosaminidase levels as a biomarker of renal tubular cell injury and urinary 8-OHdG as a biomarker of oxidative stress in 24-hour urine samples. Removed kidneys were used for quantitative analysis of the superoxide dismutase level and the detection of apoptosis. Finally, we measured the amount of crystal deposits in renal tubular cells. RESULTS Urinary N-acetyl glucosaminidase and 8-OHdG levels were decreased significantly by atorvastatin treatment in this stone forming rat model. Atorvastatin treatment increased the superoxide dismutase level and inhibited the degree of renal tubular cell N-acetyl glucosaminidase compared with stone forming control group 3. A decrease in renal crystal retention was noted when excised kidneys were evaluated following atorvastatin treatment. CONCLUSIONS Atorvastatin was found to have inhibitory effects on the renal tubular cell injury and oxidative stress caused by oxalate and crystals. Atorvastatin inhibited renal crystal retention. We believe that atorvastatin could help prevent and treat renal crystal formation.

Effect of sex hormones on crystal formation in a stone-forming rat model.

OBJECTIVES To evaluate the contribution of sex hormones in urolithiasis using a stone-forming rat model. Gender differences because of sex hormones are thought to influence the incidence of urolithiasis. METHODS We divided rats into 7 groups, such as intact males, orchidectomized males, intact males subcutaneously implanted with testosterone, intact males subcutaneously implanted with estradiol, intact females, ovariectomized females, and intact females subcutaneously implanted with testosterone. At 10 weeks old, the rats were fed 0.5% ethylene glycol in drinking water and given 0.5 microg of 1,25-dihydroxy vitamin D(3). Kidney crystal deposition and the degree of oxidative stress were examined in each group, and endogenous oxalate metabolism and antioxidant enzymes were compared among groups using real-time reverse transcription-polymerase chain reaction. RESULTS Extensive crystal deposition was observed in intact males and testosterone-administered males, whereas few crystals were found in intact females. Crystal deposition was inhibited in orchiectomized males and in those administered estradiol, whereas ovariectomized females and testosterone-administered females had slightly enhanced and very enhanced crystal deposition, respectively. Increases in urinary oxalate excretion paralleled renal crystal deposition, which were both enhanced by testosterone treatment through increased glycolate oxidase expression. Oxidative stress increased in groups with extensive crystal deposition compared with those without. Antioxidant enzyme expression was enhanced by estradiol. CONCLUSIONS Testosterone was a promoter and estradiol an inhibitor of kidney crystal deposition, likely because of their effects on oxalate synthesis and oxidative stress.

Possible causes for the low prevalence of pediatric urolithiasis

OBJECTIVES To determine why the incidence of pediatric urolithiasis is less than that of adult urolithiasis, we investigated the difference in inhibition of calcium oxalate (CaOX) crystallization between pediatric and adult urinary macromolecules (UMMs). METHODS Urinary parameters in relation to urolithiasis, the inhibition of CaOX crystallization of original urine and urine from which UMMs (greater than 3 kDa) had been removed, and the inhibition of CaOX crystal growth and aggregation of UMMs alone were measured. These inhibitory activities were compared between children and adults. RESULTS In the original urine, the inhibition of CaOX crystallization was significantly stronger for children than for adults, but was the same in urine from which the UMMs had been removed. The inhibition of CaOX crystal growth by UMMs alone showed no significant differences between children and adults; their inhibition of CaOX crystal aggregation was significantly stronger for children than for adults. Much more glycosaminoglycan (GAG) was included in pediatric UMMs than in adult UMMs, although there was no difference in UMM concentration between urine from children and urine from adults. CONCLUSIONS The lower incidence of CaOX lithiasis in children may be attributed, among other factors, to the stronger inhibition of CaOX crystal aggregation by pediatric UMMs, which in turn might be affected by the higher concentration of GAGs in childrens urine.

Renal cell carcinoma : Preoperative assessment for enucleative surgery with angiography, CT, and MRI

PURPOSE Our purpose was to assess various imaging methods in detecting a pseudocapsule of renal cell carcinoma (RCC), which is critical for successful tumor enucleation. METHOD In 42 patients with histopathologically proven RCC, images obtained at angiography (n = 42), CT (n = 30), and MRI (n = 19) were investigated retrospectively. All patients underwent treatment (enucleation: n = 15; nephrectomy: n = 27). The imaging criteria for the presence of a pseudocapsule were as follows: a surrounding radiolucent rim on angiography, a low or high density rim on CT, and a low intensity rim on MRI. All images were retrospectively reviewed by three radiologists without knowledge of the clinical and histological findings. RESULTS Thirty-three of 42 RCCs showed a pseudocapsule on the surgical specimen. A pseudocapsule was detected in 67% of tumors (22/33) on angiography, 26% (6/23) on CT, 27% (4/15) on T1-weighted MRI, 93% (14/15) on T2-weighted MRI, 67% (8/12) on dynamic enhanced T1-weighted MRI, and 15% (2/13) on delayed enhanced T1-weighted MRI. CONCLUSION T2-weighted MR images are superior for visualizing a pseudocapsule of RCC and for providing reliable selection criteria for tumor enucleation.

Why does atorvastatin inhibit renal crystal retention

Recently, we reported that atorvastatin prevents renal tubular cell injury by oxalate and inhibits renal crystal retention. In this study, we investigated the mechanism by which atorvastatin inhibits renal crystal retention. Male Sprague-Dawley rats were separated into four experimental groups, and the ethylene glycol model of hyperoxaluria and the atorvastatin treatment model were analyzed. To clarify the mechanism by which atorvastatin inhibits renal crystal retention, the removed kidneys were used for the quantitative analysis of superoxide dismutase (SOD) and catalase. The subunits of the NADPH oxidase system were evaluated using real-time polymerase chain reaction analysis. Furthermore, the level of transforming growth factor-β (TGF-β) in kidney tissue was compared in each group. Atorvastatin treatment increased the SOD and catalase level compared with the stone-forming control group. Atorvastatin treatment decreased the expression of NOX-1 mRNA. Furthermore, the level of TGF-β was suppressed by atorvastatin treatment. We found that atorvastatin have inhibited calcium oxalate (CaOX) urolithiasis formation. We hypothesize that the mechanism of action of atorvastatin involves inhibiting TGF-β and NADPH oxidase, and increasing the SOD and catalase level. We believe that atorvastatin will be helpful in the treatment of CaOX urolithiasis.

Laparoscopic diagnosis and treatment of nonpalpable testis

Abstract Objective: Laparoscopy has become one of the important diagnostic modalities of nonpalpable testis and has been developed and applied in the treatment of this disease. In the present study, we investigated the usefulness of laparoscopy in the diagnosis and treatment of nonpalpable testis.

Adverse Event Profile and Dose Modification of Everolimus for Advanced Renal Cell Carcinoma in Real-world Japanese Clinical Practice

OBJECTIVE The aim of the study was to assess the safety and efficacy of everolimus therapy for advanced renal cell carcinoma in Japanese patients receiving real-world care. METHODS Patients who had been treated with everolimus for advanced renal cell carcinoma at 39 Japanese medical centers between January 2010 and November 2011 were retrospectively investigated to assess adverse events and the time to treatment failure. RESULTS A total of 180 patients were identified. Their median age was 65 years (range 23-93). The median time to treatment failure was 2.9 months (95% confidence interval 2.4-3.4). The median time to treatment failure was significantly longer in patients with dose modification (4.2 months; 95% confidence interval 3.4-5.0) than in patients without dose modification (1.7 months; 95% confidence interval 1.0-2.3; P < 0.01) after experiencing adverse events. Stomatitis (44%) was the most frequent adverse event, followed by thrombocytopenia (31%), anemia (22%), interstitial pneumonia (22%) and hyperglycemia (17%). Interstitial pneumonia was the most frequent cause of discontinuation in patients who discontinued everolimus due to intolerability regardless of the dose modification status. None of the patients with dose modification of everolimus discontinued everolimus due to thrombocytopenia or leukopenia. CONCLUSIONS The adverse event profile of everolimus may differ between Japanese and Caucasian patients. Dose modification of everolimus might be associated with longer treatment duration in patients with advanced renal cell carcinoma. Further studies are required to clarify this association. Interstitial pneumonia may be difficult to overcome by dose modification.