Takeshi Usami

Nagoya City University, Nagoya, Aichi, Japan

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Publications (29)122.34 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: We recently showed regional differences in the incidence of end-stage renal disease (ESRD) within Japan, which is generally ethnically homogenous, suggesting that factors other than genetic may contribute to the difference. We examined regional differences in the amounts of dietary nutrient intake, especially protein in our search for an explanation. Annually, the Japanese Society for Dialysis Therapy reports the numbers of patients entering maintenance dialysis in each prefecture of Japan. We used these numbers from 1984 to 2002 to calculate the annual ESRD incidence in each of 12 regions of Japan. The regional differences were analyzed in relation to the amounts of nutrient intake reported annually by National Nutrition Survey in corresponding regions for these 19 years. Each year, approximately 15,000 subjects from 5000 households in randomly selected 300 districts were included to obtain a representative sample of the entire population of Japanese in a manner of age, sex, and body mass matched. There were marked regional differences in the annual ESRD incidence and small regional differences in dietary intake of each nutrient. Multiple regression analysis showed that the annual ESRD incidence was negatively correlated with energy intake (r = -0.65, F = 240, n = 228) and positively correlated with animal protein intake (r = 0.25, F = 30). Across 12 regions in the values averaged for 19 years in each region, however, the incidence of ESRD was negatively correlated only with the amounts of energy intake (r = -0.74, F = 12, n = 12), but not with animal protein (r = 0.07, F = 0.04). The present study, relating regional differences between ESRD dynamics and the amounts of nutrient intake in a nationwide population of Japan, revealed that the renal protective effects of dietary restriction of protein, suggested by animal models of progressive nephropathies but yet unproved by large-scale clinical trials, remained unestablished even on a macro level of whole Japan through mapping approaches.
    Journal of Renal Nutrition 04/2007; 17(2):118-25. · 1.75 Impact Factor
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    ABSTRACT: Patients with infective endocarditis (IE) often have renal complications which may include infarcts, abscesses and glomerulonephritis (GN). Furthermore, it is generally accepted that there is an association between IE and anti-neutrophil cytoplasmic antibody (ANCA). Here, we report the case of a 24-year-old man who developed rapidly progressive GN in the course of IE due to infection with alpha-streptococcus. The initial clinical manifestation of the condition was severe sacroiliitis without fever. Sandwich ELISA showed that the patient was positive for PR3-ANCA at low titer, and the classical complement pathway was also activated. Renal biopsy demonstrated several lesions: focal embolic GN, GN with immune deposits and focal and segmental crescentic necrotizing GN. Treatment with antibiotics and steroids led to eradication of the infection, and resolution of the renal disease was accompanied by immediate disappearance of PR3-ANCA and hypocomplementemia. During a 4-year follow-up period, no recurrence was observed. There have only been 7 case reports of GN associated with IE and PR3-ANCA in which the renal pathology has been described, and the current report is the first to document renal pathology in a patient with isolated pulmonic valve IE and PR3-ANCA. Moreover, this report is the first to show a change in renal biopsy findings in response to treatment. A review of the 7 literature cases and that of our patient showed that none involved pauci-immune GN. Hence, further studies are needed to clarify the prevalence of pauci-immune GN in ANCA-positive IE patients.
    Clinical nephrology 10/2006; 66(3):202-9. · 1.29 Impact Factor
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    ABSTRACT: Nocturnal polyuria has been well known in renal insufficiency. Recently, we found that as renal function deteriorated in chronic kidney disease (CKD), natriuresis was enhanced during the night with nocturnal blood pressure elevation. In the present study, we investigated whether nocturnal polyuria in CKD was due to the inability to concentrate urine, as previously proposed, or based on osmotic diuresis mainly by natriuresis. In 27 CKD patients, circadian rhythms of urinary sodium, potassium, urea and osmolar excretion rates (U(Na)V, U(K)V, U(urea)V, U(osm)V) as well as of urinary volume (V) and free-water clearance (C(H(2)O)) were estimated during both daytime (6:00 to 21:00) and nighttime (21:00 to 6:00). Then, the night/day ratios of these parameters were analysed in relation to creatinine clearance (C(cr)) as a marker of glomerular filtration rate. C(cr) had significantly negative relationships with night/day ratios of V (R = -0.69; P < 0.0001), U(osm)V (R = -0.54; P = 0.004) and U(Na)V (R = -0.63; P = 0.0005), but no correlation with night/day ratios of C(H(2)O) (R = -0.33; P = 0.1), U(K)V (R = -0.29; P = 0.1) or U(urea)V (R = -0.31; P = 0.1). Linear and multiple regression analysis identified nocturnal natriuresis rather than urea excretion as an independent determinant of nocturia. As renal function deteriorated, nocturnal polyuria was seen, being consistent with classical recognition. Furthermore, this increase in nocturnal urine volume seemed related to osmotic diuresis mainly by natriuresis rather than to water diuresis or urea excretion.
    Nephrology Dialysis Transplantation 08/2006; 21(8):2172-7. · 3.37 Impact Factor
  • Takeshi Usami, Genjiro Kimura
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    ABSTRACT: Remarkable regional differences in the annual incidence of endstage renal disease (ESRD) was found within Japan, which has a relatively homogeneous ethnic composition. In addition, there existed no regional difference in the incidence of ESRD due to polycystic kidney disease, the major genetic disorder of the kidneys. These findings suggest that the presence of factors other than genetic disposition contribute to the differences. On the other hand, there were similar regional variations in the incidences of ESRD between two causes of ESRD: chronic glomerulonephritis and diabetic nephropathy. Because it is unlikely that the regional distribution of underlying disease incidence and the disease-specific progression rate would be similar for two different causes, this observation suggests that factors governing the progression rate, which operate commonly for all causes of ESRD but differ among regions, may play an important role in generating the regional differences. Finally, we examined regional differences in the amounts of inhibitors of the renin-angiotensin system used, especially angiotensin-converting enzyme (ACE) inhibitors, in our search for an explanation of the regional differences in ESRD dynamics. Among antihypertensive agents examined, only ACE inhibitors were negatively correlated with the annual incidence of ESRD. The renal protective effects of ACE inhibitors have been established by results with animal models of progressive nephropathy and by large-scale clinical trials. Our epidemiological results for Japan as a whole show the same protective effects still more convincingly from a different approach. It is not completely clear yet at present, however, how regional variations in the incidence of ESRD are generated. If we could identify in future the factors that contribute to the regional differences, strategies for the treatment of renal disease will become available from different angles. Thus, much effort will be encouraged for the further analysis of regional differences in ESRD dynamics.
    Clinical and Experimental Nephrology 04/2006; 10(1):8-12. · 1.25 Impact Factor
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    ABSTRACT: We recently showed that there were clear regional differences in the dynamics of end-stage renal disease (ESRD) within Japan, which has an ethnically homogenous population. We speculate on the reason for these regional differences by correlating the regional distributions in the incidence of ESRD due to each of the following individual causes of ESRD: chronic glomerulonephritis (CGN), diabetic nephropathy (DMN) and polycystic kidney disease (PKD). The number of ESRD patients entering maintenance dialysis therapy due to individual causes of renal disease in each prefecture was reported annually for a 6-year period by the Japanese Society for Dialysis Therapy. After combining data from several prefectures into 11 geopolitical regions in Japan, the mean annual incidence of ESRD across the 11 regions was correlated among the three causes of ESRD. There were significant regional differences in the incidence of ESRD due to CGN (P<0.0001) and DMN (P=0.0015), the distributions of which were similar to each other across the 11 regions. In contrast, no regional differences were found in the incidence of ESRD due to PKD (P=0.6) as the major genetic disorder of the kidneys, suggesting that genetic backgrounds are relatively uniform throughout Japan. The regional distributions due to PKD were not correlated with those due to other causes: CGN and DMN. Risk factors common to nephropathy progression, rather than an underlying disease incidence and genetic predisposition, might contribute to regional differences in the overall ESRD incidence in Japan. Other possibilities such as the prevalence of underlying diseases, and acceptance or rejection rates into treatment programmes must be considered further for better explanations.
    Nephrology 08/2005; 10(4):400-4. · 1.69 Impact Factor
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    ABSTRACT: We present the case of a 69-year-old man with nephrotic syndrome and renal insufficiency, who developed lobular glomerulonephritis. An electron microscopy examination of a renal biopsy showed microtubular structures of 24 nm in diameter in the subendothelial space and the paramesangial area. These deposits were PAS-positive and Congo red-negative, and revealed predominantly positive staining for kappa light chain. There was no evidence of diseases with highly organized glomerular deposits, such as amyloidosis, cryoglobulinemia, systemic lupus erythematosus or paraproteinemia. Therefore, the patient was diagnosed to have immunotactoid glomerulopathy (ITG). During a seven-year course he has not developed any disease known to be associated with organized glomerular immune deposits. Hence, we believe ITG occurred as a primary glomerular disease in this case. We also highlight cases of ITG with microtubular deposits that have been reported in Japan, compare these cases to previous reports, and show that the characteristics of the Japanese cases are male predominance; a high incidence of membranoproliferative glomerulonephritis (MPGN); a low incidence of monoclonal gammopathy and hematological malignancies and a higher incidence of hypocomplementemia.
    Clinical nephrology 06/2005; 63(5):368-74. · 1.29 Impact Factor
  • Takeshi Usami, Genjiro Kimura
    Nippon rinsho. Japanese journal of clinical medicine 04/2005; 63 Suppl 3:149-54.
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    Kidney International 05/2004; 65(4):1520. · 8.52 Impact Factor
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    Michio Fukuda, Takeshi Usami, Genjiro Kimura
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    ABSTRACT: Hypertensive nephrosclerosis is the second most common cause of end-stage renal disease, however morphologic evidence on the subject is poorly understood. A perennial and vexing problem in understanding kidney hypertension is that correlations between hypertension and vascular and glomerular lesions are only moderate, in part because all of these lesions are present to a greater or lesser degree in the normotensive, aging kidney, with racial differences in severity further compounding the problem. This review looks at newer data on this topic. Recent data suggest that there are two different processes leading to glomerulosclerosis, and the combination of the two begins to explain why global correlations between hypertension and morphologic lesions are destined to remain poor. Arterial stiffening with increased pulse pressure down as far as the afferent arteriolar level likely plays an important role in the progression of glomerular lesions. Loss of renal autoregulation with glomerular hypertrophy, hyperfiltration, and focal segmental glomerulosclerosis is now recognized to contribute significantly to nephrosclerosis, particularly in the black population. Ischemic glomerulosclerosis, however, may ultimately be the most important lesion, with consequent hypoxia in the parenchyma beyond, leading to tubular atrophy and interstitial fibrosis. Hypertensive nephrosclerosis should be seen as a process with two principal modes of glomerular sclerosis, ischemic and hypertrophic, with consequent focal segmental glomerulosclerosis, contributing variably to renal failure according to race and level of hypertension.
    Nippon rinsho. Japanese journal of clinical medicine 04/2004; 62 Suppl 3:357-62.
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    ABSTRACT: We reported that patients with sodium sensitive type of hypertension exhibited the lack of nocturnal fall in blood pressure with enhanced natriuresis during night. Sodium sensitivity is caused by diminished glomerular filtration capability and/or augmented tubular reabsorption of sodium, and seems tightly linked with glomerular capillary hypertension. In the present study, we investigated the relationship between glomerular filtration rate and circadian rhythms of these parameters in patients with glomerulopathy. Twenty six patients (15 men and 11 women; aged 17 to 72 years; mean age 47 +/- 3 years), whose diagnosis was confirmed as glomerulopathy with renal biopsy, were studied during hospitalization. Ambulatory blood pressure for 24 hours was monitored, while urinary samples were collected for both daytime (6:00 a.m. to 9:00 p.m.) and nighttime (9:00 p.m. to 6:00 a.m.) to estimate circadian rhythms of urinary sodium and protein excretion rates (UNaV, UproV). Then night/day ratios of mean arterial blood pressure (MAP), UNaV, and UproV were analyzed in relation to 24-hour creatinine clearance as a marker of glomerular filtration rate. Serum creatinine and creatinine clearance were 1.1 +/- 0.1 mg/dL and 89 +/- 7 mL/min/1.73 m2. There were significant day-night differences in MAP (96 +/- 2 mm Hg vs. 92 +/- 2 mm Hg; P= 0.006), UNaV (6.7 +/- 0.9 mmol/hour vs. 3.6 +/- 0.3 mmol/hour; P= 0.003), and UproV (161 +/- 27 mg/hour vs. 128 +/- 28 mg/hour; P= 0.02). Creatinine clearance had significantly negative relationships with night/day ratios of MAP (r=-0.49; P= 0.01), UNaV (r=-0.43; P= 0.03,) and UproV (r=-0.41; P= 0.04). In addition, night/day ratio of MAP had significantly positive relationships with night/day ratios of UNaV (r= 0.49; P= 0.01) and UproV (r= 0.45; P= 0.02). Our results show that as renal function deteriorates in glomerulopathy the nocturnal dip in blood pressure is lost, resulting in enhanced urinary sodium and protein excretions during night. These findings are compatible with our proposal that impaired natriuresis during daytime makes nocturnal blood pressure elevated to compensate for diminished natriuresis by pressure natriuresis. We speculate that nocturnal glomerular capillary hypertension contributes, at least in part, to enhanced urinary sodium and protein excretions during night.
    Kidney International 03/2004; 65(2):621-5. · 8.52 Impact Factor
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    ABSTRACT: Pre-eclampsia is the abnormality of blood circulation in late pregnancy, often caused by renal failure, hemolysis, elevated liver enzyme, low platelet syndrome, and eclampsia. We present a case of severe pre-eclampsia with placental abruption in a 24-year-old woman, pregnant for the first time. The patient was diagnosed with congestive heart failure, which came as a result of pre-eclampsia. Anti-hypertensive drugs were used for its treatment.
    Journal of Obstetrics and Gynaecology Research 11/2003; 29(5):339-42. · 0.84 Impact Factor
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    ABSTRACT: We recently found regional differences in the incidence of end-stage renal disease (ESRD) in Japan, which is generally ethnically homogeneous, suggesting that factors other than genetic may contribute to the difference. Here, we examined regional differences in the amounts of expenses spent on antihypertensives, especially angiotensin-converting enzyme (ACE) inhibitors, in our search for an explanation. Annually, the Japanese Society for Dialysis Therapy reports the numbers of patients entering maintenance dialysis in each prefecture of Japan since 1982. We used the findings for 1995 to 2000 to calculate the annual incidence of ESRD in each of the 11 regions of Japan. In addition, regional differences in annual amounts paid for antihypertensive drugs, presumably corresponding to the amounts used, during the same 6 years, corrected for population, were estimated. As in our 1982 to 1998 study, the incidence of ESRD was high in Okinawa, Kyushu, and Shikoku, while low in Hokuriku, Koshinetsu, and Tohoku (P < 0.0001) [one-way repeated measures analysis of variance (ANOVA)]. We found regional differences in the corrected sum paid for total antihypertensive drugs, ACE inhibitors and calcium antagonists. Only ACE inhibitors were negatively correlated with the incidence of ESRD by linear and multiple regression analyses. The renal protective effects of ACE inhibitors have been established by results with animal models of progressive nephropathy and large-scale clinical trials. Our epidemiologic results for Japan as a whole show the same protective effects still more convincingly from a different approach.
    Kidney International 11/2003; 64(4):1445-9. · 8.52 Impact Factor
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    ABSTRACT: Although it has been repeatedly shown that the oral carbonaceous absorbent AST-120 ameliorates the progression of chronic renal failure, the mechanisms remain unknown. Male Sprague-Dawley rats (6 weeks old), weighing 180-210 g, were 4/5 nephrectomized, and were divided into two groups: one given AST-120 (0.4 g/100 g body weight BW; n= 9) and the other not given AST-120 ( n = 9). Body weight, blood pressure, and serum and urine chemistry, as well as the plasma components of the renin-angiotensin system, were measured for 22 weeks. Proteinuria was significantly greater in the controls than in the AST-120 group (102 +/- 22 vs 51 +/- 7 mg/day at 22 weeks). Urea clearance was lower in the former (3.7 +/- 0.4 vs 3.9 +/- 0.4 ml/min). There were no differences in plasma renin activity (1.4 +/- 0.3 vs 1.9 +/- 0.4 mg/ml per h), or in angiotensin I (756 +/- 119 vs 1042 +/- 168 pg/ml) and II (35.1 +/- 7.4 vs 46.6 +/- 7.6 pg/ml) or angiotensin-converting enzyme activity (39.0 +/- 2.4 vs 37.9 +/- 2.2 IU/l) between the two groups. Protein intake, estimated from urinary urea appearance, was not different. Serum phosphate concentration (6.6 +/- 0.3 vs 5.9 +/- 0.3 mg/dl) was higher in the control than in AST-120, while the urinary phosphate excretion rate (31.5 +/- 0.8 vs 28.1 +/- 1.8 mg/day) tended to be lower in the latter. Conclusions. AST-120 retarded the progression of renal failure in the 4/5 renal ablation model without affecting the plasma renin-angiotensin system or protein intake, both of which were the most important risk factors for the progression of renal failure. We hypothesize that the renal protective effects of the oral absorbent AST-120 may be, at least in part, due to its lowering phosphate absorption from the diet as a phosphorus binder.
    Clinical and Experimental Nephrology 07/2003; 7(2):120-4. · 1.25 Impact Factor
  • JAMA The Journal of the American Medical Association 04/2003; 289(9):1102-3; author reply 1103. · 29.98 Impact Factor
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    ABSTRACT: Acute humoral rejection (AHR) is the most important risk factor for early graft loss in ABO-incompatible (ABO-i) kidney transplantation (RTx). The pathogenesis and diagnostic criteria for AHR after ABO-i RTx remain unclear. Complement fragment C4d deposition in peritubular capillaries (PTC), which is a sensitive indicator for activation of the classical complement pathway, was studied to establish the pathologic diagnostic indicator of AHR. Forty-four graft biopsy specimens from 19 patients with ABO-i living donors were analyzed within 90 days after RTx. Nineteen biopsy specimens with acute rejection after ABO-compatible (ABO-c) living-related RTx were used as controls. Diffuse and bright C4d deposition in PTC was considered significantly positive. All of 8 recipients with AHR showed significantly positive C4d in PTC in the ABO-i group, but 9 of 11 recipients without AHR were negative. In the ABO-c RTx group, 16 of 19 recipients were negative for C4d in PTC. The prevalence of C4d in PTC was significantly higher in ABO-i RTx (P<0.05). C4d deposition is valuable as a specific and sensitive indicator for AHR, even of mild severity, in ABO-i RTx.
    Transplantation 03/2003; 75(5):663-5. · 3.78 Impact Factor
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    ABSTRACT: Regional variations in end-stage renal disease have been found within a country, even within a race. Since diabetic nephropathy is the leading cause of end-stage renal disease in developed countries, first of all, regional differences in diabetic nephropathy must be considered. Although the incidence of end-stage renal disease due to diabetic nephropathy has been found to differ among different areas within a country, there are no data on regional variations in the incidence of type II diabetes or diabetic nephropathy without renal failure. Such regional variations could hardly be explained by local differences in gene pools alone, which suggests an important role of environmental factors. It is not clear at present how regional variations in the incidence of end-stage renal disease are generated. If we can identify the factors that contribute to the regional differences, we can take these into account in future treatment strategies for renal disease. Thus, much effort is required in further analysis of regional differences in end-stage renal disease dynamics.
    Current Opinion in Nephrology and Hypertension 06/2002; 11(3):343-6. · 3.96 Impact Factor
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    ABSTRACT: Hyperhomocysteinaemia, which is considered to be induced by impairment of the remethylation pathway in patients with chronic renal failure (CRF), cannot be cured solely by folic acid therapy. In the present study, we investigated the additional benefit of administration of methylcobalamin, which is a co-enzyme in the remethylation pathway, on lowering total homocysteine (tHcy) plasma concentrations in haemodialysis (HD) patients receiving high-dose folic acid supplementation. In order to assess the efficacy on lowering plasma tHcy levels (fasting concentration), 21 HD patients, were randomly assigned and provided folic acid supplementation: 15 mg/day orally (group I, n=7); methylcobalamin 500 mg intravenously after each HD, in addition to folic acid (group II, n=7); or vitamin B(6) (B(6)), 60 mg/day orally, in addition to folic acid and methylcobalamin (group III, n=7). All patients were treated for 3 weeks. A methionine-loading test was conducted before and after supplementation. The following measurements were also made before and after supplementation for each group: serum folic acid, B(6), and vitamin B(12) (B(12)) concentrations (including measurement of proportion of methylcobalamin fraction). Twelve HD patients receiving methylcobalamin alone served as the HD control group and seven healthy volunteers served as the normal control group for this study. In our randomized HD patients the proportions of methylcobalamin fraction (48.3+/-7.5%) and plasma vitamin B(6) concentration (2.9+/-1.1 ng/ml) were significantly lower than in the normal controls (methylcobalamin 58.7+/-2.2%, P<0.01; B(6) 20.1+/-10.8 ng/ml, P<0.01), while folic acid and vitamin B(12) were not significantly different from the normal controls. Mean percentage reduction in fasting tHcy was 17.3+/-8.4% in group I, 57.4+/-13.3% in group II, 59.9+/-5.6% in group III, and 18.7+/-7.5% in HD controls. The power of the test to detect a reduction of tHcy level was 99.6% in group II and 99.9% in group III when type I error level was set at 0.05. Groups II and III had normal results for the methionine-loading test after treatment. Treatment resulted in normalization of fasting tHcy levels (<12 ng/ml) in all 14 patients treated by the combined administration of methylcobalamin and supplementation of folic acid regardless of whether there was supplementation of vitamin B(6). The benefit of methylcobalamin administration on lowering plasma tHcy levels in HD patients was remarkable. Our study suggested that both supplementations of high-dose folic acid and methylcobalamin are required for the remethylation pathway to regain its normal activity. This method could be a therapeutic strategy to combat the risk associated with atherosclerosis and cardiovascular disease in patients with chronic renal failure.
    Nephrology Dialysis Transplantation 05/2002; 17(5):916-22. · 3.37 Impact Factor
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    ABSTRACT: We report the case of a young pregnant woman with bilateral renovascular hypertension due to renal microaneurysms from an unknown cause, who had a successful delivery. Pregnancy did not affect the disease activity even in the postpartum period. Her blood pressure was maintained within the normal range by administration of labetalol. Although the angiographic appearance of the symmetrical aneurysms in both renal artery beds from the interlobular to arcuate artery levels suggested polyarteritis nodosa of multiple microaneurysms in the bilateral interlobular arteries, the clinical features suggested other causes of renovascular hypertension, such as fibromuscular dysplasia and/or congenital microaneurysms. We were thus unable to reach a definitive diagnosis.
    Hypertension Research 02/2001; 24(1):83-5. · 2.79 Impact Factor
  • Transplantation Proceedings 09/2000; 32(5):841-2. · 0.95 Impact Factor
  • Transplantation Proceedings 09/2000; 32(5):1097. · 0.95 Impact Factor

Publication Stats

376 Citations
122.34 Total Impact Points

Institutions

  • 1997–2006
    • Nagoya City University
      • Department of Internal Medicine
      Nagoya, Aichi, Japan
  • 2000–2004
    • Nagoya University
      • Division of Surgery
      Nagoya, Aichi, Japan
  • 1996–1997
    • Kyoto Daini Red Cross Hospital
      Kioto, Kyōto, Japan