Mitsuhiko Okuyama

Improvement of stone comminution by slow delivery rate of shock waves in extracorporeal lithotripsy

Aim: The aim of this study was to investigate the effect of delivery rate of shockwaves (SW) on stone comminution and treatment outcomes in patients with renal and ureteral stones.

Identification of bikunin isolated from human urine inhibits calcium oxalate crystal growth and its localization in the kidneys

Background: We previously reported a high molecular weight substance purified from human urine that strongly inhibited calcium oxalate (CaOx) crystal growth in vitro. In the study present herein, we identified and investigated a protein purified from human urine that strongly inhibits CaOx crystal growth using a column chromatography series.

EARLY STAGE OF UROLITHIASIS FORMATION IN EXPERIMENTAL HYPERPARATHYROIDISM

PURPOSE We have previously noted marked acceleration in the proliferative activity of parathyroid cells in rats with spontaneous hypercholesterolemia and secondary hyperparathyroidism. Using this proliferative potential we investigated whether transplantation of these enlarged parathyroids into normal rats would induce hyperparathyroidism and renal stones. MATERIALS AND METHODS We used 26-week-old male rats with spontaneous hypercholesterolemia as donors, and 5-week-old normal male Sprague-Dawley rats and rats with spontaneous hypercholesterolemia as recipients. Enlarged parathyroid glands were transplanted into group 1--Sprague-Dawley rats with no treatment, group 2--Sprague-Dawley rats that received FK-506 as an immuno-suppressor, group 3--rats with spontaneous hypercholesterolemia rats that underwent parathyroidectomy plus FK-506 administration and group 4--Sprague-Dawley rats that underwent parathyroidectomy plus FK-506 administration. Parathyroidectomy was performed in recipients before transplantation to ensure a low calcium condition. RESULTS Grafts were rejected within 11 and 15 weeks in groups 1 and 2, respectively. In group 3, 78% of the grafts were successful even after 19 weeks. In group 4 graft survival was 30% at 15 weeks with complete rejection at 19 weeks. In group 3 gradually elevated serum parathyroid hormone was observed as well as stone plaques containing calcium oxalate and calcium phosphate in renal tubules located mainly in the corticomedullary junction. An increased number of plaques was associated with higher parathyroid hormone. CONCLUSIONS Our study shows that transplanted parathyroid glands function with an immunosuppressive agent and the maintenance of hypocalcemic conditions, and they secrete sufficient parathyroid hormone to demonstrate hyperparathyroidism. Plaque in these kidneys indicates an early stage of urolithiasis caused by hyperparathyroidism.

Three cases of urolithiasis associated with sarcoidosis: A review of Japanese cases

Abstract:  We report three cases of urolithiasis associated with sarcoidosis and reviewed the Japanese published reports. All cases had hypercalcemia, hyperuricemia, hypercalciuria and renal dysfunction. A serum level of 1,25‐(OH)2D3 was elevated and intact parathyroid hormone (PTH) was decreased. Stone components were predominantly calcium oxalate. Abnormal calcium metabolism is a well‐known feature of sarcoidosis and the reported prevalence of urolithiasis in patients with sarcoidosis was 1.3–14.0% in the English published reports. However, urolithiasis associated with sarcoidosis is uncommon in Japan and we could find only 16 documented cases including ours. Abnormal calcium metabolism is caused by an increase in serum concentration of 1,25‐(OH)2D3, which is derived from endogenous overproduction in the pulmonary macrophages. If patients with urolithiasis have abnormal calcium metabolism, renal impairment and suppression of PTH, the possibility of sarcoidosis should be considered for a differential diagnosis. Also, it should be emphasized that the presence or developing of urolithiasis is to be monitored during follow up of patients with sarcoidosis.

Immunohistochemical expression of P-glycoprotein in the rat urinary bladder and the effect of verapamil on intravesical chemotherapy

Abstract Background: The expression of P‐glycoprotein (Pgp) is thought to be common in bladder epithelium and the multidrug resistance mediated by Pgp must be considered to improve the efficacy of chemotherapy for bladder tumors.