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Featured researches published by Tetsuo Yasumasu.


International Journal of Urology | 2001

Resection of an L‐shaped kidney with renal cell carcinoma using a microwave tissue coagulator

Hiroaki Tsunoe; Tetsuo Yasumasu; Masatosi Tanaka; Nobuyuki Kai; Seiji Naito

Abstract An L‐shaped kidney is a type of crossed fused renal ectopia and consists of two moieties which were originally two kidneys. It is an uncommon condition and cases of malignant tumors in such anomalies are exceedingly rare. A case of an L‐shaped kidney with renal cell carcinoma is herein reported, in which a separation of both moieties was done in situ in order to perform a tumor resection. A literature review of this topic is also reported and the findings are discussed.


International Urology and Nephrology | 1994

Clinical study of asymptomatic microscopic haematuria

Tetsuo Yasumasu; Yasuhiro Koikawa; Jiro Uozumi; Toyofumi Ueda; J. Kumazawa

A clinical statistical survey was performed on 355 patients with asymptomatic microscopic haematuria. Urologic lesions were detected in 19.4% of the patients. Urologic lesions requiring surgical treament were found in only two patients with bladder carcinoma and with renal calculus. With the exception of glomerulonephritis, the proportion of those over 40 years who had urologic lesions was higher. It is suggested that an initial evaluation based on excretory urography, cystoscopy and ultrasonography is more important for patients over 40 years.


Research in Experimental Medicine | 1995

The effect of methylprednisolone on cisplatin-induced nephrotoxicity in rat renal cortical slices

Jiro Uozumi; Yasuhiro Koikawa; Tetsuo Yasumasu; Toyofumi Ueda; Joichi Kumazawa

To investigate the protective action of methylprednisolone against cisplatin nephrotoxicity, the effect of in vivo pretreatment with methylprednisolone on the cisplatin-induced reduction inp-aminohippurate (PAH) accumulation and gluconeogenesis was examined using renal cortical slices prepared from Sprague-Dawley rats. The PAH accumulation in the kidney slices prepared from methylprednisolone-pretreated rats was significantly reduced following in vitro incubation with 2 mM cisplatin, to a degree equal to that observed in the slices prepared from untreated rats. However, the inhibitory effect of cisplatin on gluconeogenesis in the renal cortical slices obtained from methylpredimisolone-pretreated rats was significantly smaller than that seen in the slices from untreated rats. Our present studies suggest that in vivo pretreatment with methylprednisolone may contribute to its protective effect against cisplatin nephrotoxicity through the process of gluconeogenesis in renal epithelial cells.


Journal of Pharmacy and Pharmacology | 1992

Ultrastructural Alterations and DNA Synthesis of Renal Cell Nuclei following Cisplatin or Carboplatin Injection in Rats

Tetsuo Yasumasu; Toyofumi Ueda; Jiro Uozumi; Yukitaka Mihara; Yasuhiro Koikawa; Joichi Kumazawa

Abstract— To clarify the difference in nephrotoxicity between cisplatin and carboplatin, ultrastructural alterations and DNA synthesis of renal cell nuclei were studied in Sprague‐Dawley rats which had received intravenously either cisplatin or carboplatin at an equitoxic dose. Twelve hours after cisplatin injection, nucleolar segregation accompanied by aggregated nuclear heterochromatin was observed in the third segment of the proximal tubules. Seventy‐two hours after cisplatin injection, nuclear damage was more widespread while regenerative cells were also observed. Nuclear damage was not observed in the carboplatin‐treated rats. Nuclear DNA synthesis of renal cells was suppressed at 8, 12 and 24 h and was accelerated at 72 h after cisplatin injection. Carboplatin did not suppress nuclear DNA synthesis at any time. The results indicate that cisplatin, but not carboplatin, can affect the renal cell nuclei. Cisplatin‐induced nephrotoxicity is related to its effects on renal cell nuclei.


International Journal of Urology | 1996

The Protective Effect of Methylprednisolone against Cisplatin-Induced Nephrotoxicity in Patients with Urothelial Tumors

Jiro Uozumi; Yasuhiro Koikawa; Tetsuo Yasumasu; Noriaki Tokuda; Joichi Kumazawa

Background: Many attempts have been made to reduce the nephrotoxicity of the anticancer agent cisplatin but the number of clinically useful modalities is very limited. Our previous experiments demonstrated that in rats methylprednisolone significantly reduces the nephrotoxicity caused by cisplatin. The present clinical study was conducted to confirm the protective effects of methylprednisolone against cisplatin nephrotoxicity.


International Urology and Nephrology | 1992

Calcium blockers enhance cisplatin-induced nephrotoxicity in rats

Jiro Uozumi; Toyofumi Ueda; Tetsuo Yasumasu; Yasuhiro Koikawa; J. Kumazawa

To examine the effects of calcium blockers on nephrotoxicity caused by cisplatin, the renal function and renal accumulation of Pt in Sprague-Dawley rats given 6.5 mg/kg i.v. cisplatin simultaneously with several doses of verapamil or nicardipine were evaluated. BUN, serum creatinine and kidney Pt concentrations in rats given more than 5.0 mg/kg of verapamil were significantly higher than those of the control animals injected with 6.5 mg/kg i.v. cisplatin alone, and the increase of each value was dependent upon the dose of verapamil. BUN, creatinine and kidney Pt in rats injected with more than 0.5 mg/kg i. p. nicardipine were also significantly higher than those of the controls. Calcium blockers enhanced the renal accumulation of Pt and the nephrotoxicity of cisplatin.


International Urology and Nephrology | 1994

Clinical significance of urinary enzymes and β2-microglobulin following ESWL

Jiro Uozumi; Toyofumi Ueda; Seiji Naito; N. Ogata; Tetsuo Yasumasu; Yasuhiro Koikawa; Joichi Kumazawa

To examine the renal damage caused by shock waves, urinary excretion of enzymes and β2-microglobulin were determined before and after ESWL. Urine samples were obtained from 35 patients with renal stone and 26 patients with ureteric stone treated with ESWL. Urinary lactate dehydrogenase (LDH) levels significantly increased on day 0, just after ESWL, in both groups. In the ureteric stone group the kidneys received less shock waves than in the renal stone group. Increased urinary lactate dehydrogenase was considered to have derived from erythrocytes in urine. Elevated urinary N-acetyl-β-D-glucosaminidase (NAG) levels were also observed on day 0 after ESWL in both groups, due to unknown reasons. Indirect effect of ESWL through the sympathetic nervous system or humoral factors may contribute to increases in the urinary excretion of NAG. No significant increase was found in urinary γ-glutamyl-transpeptidase (GGTP) levels for 5 days after ESWL. Urinary β2-microglobulin (BMG) levels increased on day 0 in the renal stone group alone. In our present study, the clinical significance of urinary enzymes and BMG was not well evaluated, because urinary excretion of these indicators following ESWL were transient and mild.


Urologia Internationalis | 1993

Platinum Accumulation in the Kidney and Changes in Creatinine Clearance following Chemotherapy with Cisplatin in Humans

Jiro Uozumi; Toyofumi Ueda; Tetsuo Yasumasu; Yasuhiro Koikawa; Seiji Naito; Joichi Kumazawa; Toshiharu Kamura; Hitoo Nakano; Katsuo Sueishi

To evaluate the effects of repeated administration of cisplatin on kidney platinum (Pt) accumulation and renal function, Pt content in the kidney was determined in 31 autopsy cases and changes in creatinine clearance (CCr) were retrospectively assessed in 26 of 31 autopsy cases. There was no significant correlation between the cumulative dose of cisplatin and Pt content in the kidney. However, the kidney Pt level was correlated with the dose of cisplatin injected within a 7-month period prior to the patients death. We suggest that the dose of cisplatin injected during a relatively short period before a patients death affects Pt content in the kidney. Neither the total dose of cisplatin nor the Pt content in the kidney was significantly correlated with the decrease in CCr following chemotherapy with cisplatin.


Research in Experimental Medicine | 1996

The effect of methylprednisolone on platinum kinetics and urinary enzyme excretion following intravenous cisplatin in vivo and on the growth inhibition of LLC-PK1 cells by cisplatin in vitro

Jiro Uozumi; Yasuhiro Koikawa; Tetsuo Yasumasu; Noriaki Tokuda; Toyofumi Ueda; Joichi Kumazawa

In order to evaluate the mechanism of the protective action of methyl-prednisolone against cisplatin-induced nephrotoxicity, plastinum kinetics and urinary enzyme excretion following intravenous cisplatin, with or without methyl prednisolone, were studied in vivo. The growth inhibition of LLC-PK1 cells by cisplatin in the presence or absence of methylprednisolone was studied in vitro. Rats intravenously injected with cisplatin combined with subcutaneous methylprednisolone 4 h prior to the cisplatin injection excreted more platinum in urine than rats treated with cisplatin alone. Both plasma and kidney platinum concentrations in rats injected with both cisplatin and methylprednisolone were significantly lower than those in rats given cisplantin alone at 4 h after cisplatin injection. However, there was no significant difference in urinary excretion of lactate dehydrogenase, γ-glutamyl transpeptidase or N-acetyl-β-d-glucosaminidase between methylprednisolone-treated rats and control rats. Methylprednisolone did not affect the inhibitory effects of cisplatin on the cell growth of LLC-PK1. These findings indicate that methylprednisolone-induced increase in urinary platinum excretion, accompanied by a decrease in plasma and kidney platinum concentrations following cisplatin injection in rats, may be one of the mechanisms responsible for the protective action of methylprednisolone.


Pharmacology & Toxicology | 1992

Comparative study of cisplatin and carboplatin on pharmacokinetics, nephrotoxicity and effect on renal nuclear DNA synthesis in rats

Tetsuo Yasumasu; Toyofumi Ueda; Jiro Uozumi; Yukitaka Mihara; Joichi Kumazawa

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