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Dive into the research topics where Masafumi Yokota is active.

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Featured researches published by Masafumi Yokota.


American Journal of Kidney Diseases | 1999

Transcatheter renal arterial embolization therapy on a patient with polycystic kidney disease on hemodialysis

Yoshifumi Ubara; Hideyuki Katori; Tetsuo Tagami; Shouichirou Tanaka; Masafumi Yokota; Yoshio Matsushita; Fumi Takemoto; Toshikazu Imai; Sumio Inoue; Keihachirou Kuzuhara; Shigeko Hara; Akira Yamada

We report a patient with autosomal dominant polycystic kidney disease (ADPKD) undergoing long-term hemodialysis who underwent transcatheter arterial embolization (TAE) of the renal arteries to shrink enlarged kidneys. In 1983, the patient started hemodialysis because of chronic renal failure secondary to ADPKD. However, renal size continued to increase. In January 1997, he was admitted to our hospital with abdominal distension and anorexia, in addition to progression of anemia. Upper gastroendoscopy showed an esophageal ulcer and severe external compression of the stomach. Renal angiography using the Seldinger technique showed stretched and deformed segmental renal arteries with massive enlargement of the kidneys. TAE with stainless steel coils was performed on both renal arteries. With a rapid and progressive decrease in kidney size, anorexia and anemia were improved, and the gastrointestinal compression was eliminated. In some patients with ADPKD, renal size continues to increase even after the initiation of dialysis. In about 10 years, patients develop gastrointestinal complications, such as dysphagia, ileus, severe constipation, and intestinal perforation. Surgical procedures such as nephrectomy are not satisfactory. This report shows that TAE is a safe and effective therapy for patients with ADPKD with massively enlarged kidneys.


American Journal of Kidney Diseases | 2000

Splenectomy may improve the glomerulopathy of type ii mixed cryoglobulinemia

Yoshifumi Ubara; Shigeko Hara; Hideyuki Katori; Tetsuo Tagami; Akiko Kitamura; Masafumi Yokota; Yoshio Matsushita; Fumi Takemoto; Akira Yamada; Kiyotaka Nagahama; Mituru Hara; Kazuaki Chayama

Many patients with type II mixed cryoglobulinemia have been shown to be infected with hapatitis C virus (HCV). Therefore, interferon-alfa has become the first choice of treatment for patients with HCV-associated cryoglobulinemia. However, the disease often relapses after the discontinuation of interferon therapy. The long-term effect of interferon therapy is controversial. Therefore, a more effective therapy needs to be developed. A 62-year-old Japanese woman was admitted to our hospital for the examination of abnormal liver function tests, severe edema, and purpura in her lower extremities. Glomerulopathy secondary to HCV-related cryoglobulinemia was suspected. Her serum creatinine was increased to 2.1 mg/dL. Interferon therapy was considered initially. However, because of pancytopenia caused by liver cirrhosis and splenomegaly, splenectomy was performed in February 1997, before the start of interferon therapy. Renal biopsy specimen taken at the time of the splenectomy showed typical cryoglobulinemic glomerulonephritis. Gradually, after surgery, the patients thrombocytopenia and anemia improved, her proteinuria and hematuria were decreased, her cryocrit dropped from 15% to 5%, the Ccr increased from 21.1 mL/min to 48.8 mL/min, and the purpura in her lower extremities disappeared. A repeat renal biopsy performed in May 1998 showed marked histological improvement. Splenectomy is not widely accepted as a treatment for cryoglobulinemia. Our case suggests the possibility that the monoclonal-IgM component of the type II cryoglobulin may be formed in the spleen. In conclusion, splenectomy may be an effective therapy for cryoglobulinemia in patients with HCV-positive liver cirrhosis and pancytopenia secondary to splenomegaly.


American Journal of Kidney Diseases | 2000

Severe ectopic calcification of the intestinal wall in a patient on long-term continuous ambulatory peritoneal dialysis therapy.

Yoshifumi Ubara; Hideyuki Katori; Tetsuo Tagami; Masafumi Yokota; Akiko Kitamura; Yoshio Matsushita; Fumi Takemoto; Toshikazu Imai; Sumio Inoue; Keihachirou Kuzuhara; Shigeko Hara; Akira Yamada; Ryuko Takagawa

We report autopsy findings of a 69-year-old man on long-term CAPD therapy for 13 years who showed linear peritoneal calcification. Continuous ambulatory peritoneal dialysis (CAPD) was started in 1982. He has been administered excessive amounts of vitamin D(3) derivatives (VitD) (2.0 to 2.5 microg daily) and calcium carbonate (4 g daily) for secondary hyperparathyroidism since initiation of CAPD. In May 1995, his intact parathyroid hormone (PTH) level increased over 1,000 pg/mL. Immediately after VitD was changed from pill to liquid, the dose was increased to 5 microg daily. Although the serum calcium level remained between 4.5 and 4.9 mEq/L, and serum phosphate level was 5.0 to 7.2 mg/dL, plain abdominal radiography and computed tomography showed continuous calcification along the intestinal wall in October 1995. In spite of the continuation of CAPD therapy, he remained asymptomatic until he died of congestive heart failure in January 1997. He experienced eight episodes of peritonitis during his clinical course. Autopsy showed that numerous calcified plaques were present on the submucosal portion between the thickened serosa and the longitudinal layer of the muscularis externa. The remainder of the subserosa was fibrotic, and the small arteries had markedly thickened intima and severely narrowed lumina.


Clinical and Experimental Nephrology | 2002

Anti-glomerular basement membrane antibody disease : a case report and a review of Japanese patients with and without alveolar hemorrhage

Takao Nagashima; Yoshifumi Ubara; Tetsuo Tagami; Hideyuki Katori; Masafumi Yokota; Akiko Kitamura; Fumi Takemoto; Shigeko Hara; Akira Yamada; Kiyotaka Nagahama; Mitsuru Hara

A 73-year-old man was admitted to our hospital because he had developed loss of appetite, abnormal behaviors, and consciousness disturbances that had begun in late February 1998. On admission, a renal biopsy was performed because of progressive deterioration of renal function, as evidenced by a serum urea nitrogen (UN) level of 109 mg/dl and a serum creatinine level of 16.3 mg/dl. Light microscopic examination showed severe cellular crescent formation with fibrin deposition in glomeruli and markedly degenerated Bowmans capsule. Immunofluorescence examination revealed linear deposits of IgG along glomerular basement membranes (GBM), and granular deposits of C3 on the GBM, as well as deposits of fibrinogen in Bowmans capsule. The patient was diagnosed as having anti-GBM antibody disease, based on negative results for myeloperoxidase (MPO)/proteinase-3 (PR-3)-anti-neutrophil cytoplasmic antibody (ANCA), high serum anti-GBM antibody titers, and the absence of pulmonary hemorrhage. He was treated with both combination therapy (cyclophosphamide and prednisolone) and plasmapheresis. In spite of the disappearance of anti-GBM antibody, his renal function did not improve, and he has been treated with regular hemodialysis since March 1998. We reviewed 49 cases of anti-GBM antibody disease in patients with alveolar hemorrhage (group A; Goodpastures syndrome) and 39 cases in patients without it (group B) reported in Japan from 1975 to 1999, examining the differences between these groups, and we clarified the characteristics of these rare diseases in Japan. There was no difference in age, sex, and ANCA positivity between the two groups. The mortality rate was higher in group A (56.2%) than in group B (18.4%). About half of the patients underwent plasmapheresis, but it did not reduce the mortality rate or improve the renal prognosis.


American Journal of Kidney Diseases | 2002

Renal contraction therapy for enlarged polycystic kidneys by transcatheter arterial embolization in hemodialysis patients

Yoshifumi Ubara; Tetsuo Tagami; Naoki Sawa; Hideyuki Katori; Masafumi Yokota; Fumi Takemoto; Sumio Inoue; Keihachirou Kuzuhara; Shigeko Hara; Akira Yamada


American Journal of Kidney Diseases | 2004

Intravascular embolization therapy in a patient with an enlarged polycystic liver

Yoshifumi Ubara; Ryouji Takei; Jyunichi Hoshino; Tetsuo Tagami; Naoki Sawa; Masafumi Yokota; Hideyuki Katori; Fumi Takemoto; Shigeko Hara; Kenmei Takaichi


Internal Medicine | 2004

Severe interstitial cystitis associated with Sjögren's syndrome.

Shigeru Shibata; Yoshifumi Ubara; Naoki Sawa; Tetsuo Tagami; Junichi Hosino; Masafumi Yokota; Hideyuki Katori; Fumi Takemoto; Shigeko Hara; Kenmei Takaichi; Akiko Fujii; Hirokatu Murata; Tadahiro Nishi


Kidney International | 2003

Histomorphometric features of bone in patients with primary and secondary hypoparathyroidism

Yoshifumi Ubara; Tomohisa Fushimi; Tetsuo Tagami; Naoki Sawa; Junichi Hoshino; Masafumi Yokota; Hideyuki Katori; Fumi Takemoto; Shigeko Hara


Nephron | 1999

Relationship between erythropoietin administration and the endothelial nitric oxide synthase gene polymorphism in patients with hemodialysis.

Keitaro Yokoyama; Toshihiko Tsukada; Yoshio Matushita; Masafumi Yokota; Fumi Takemoto; Sigeko Hara; Akira Yamada; Yoshindo Kawaguchi; Tastuo Hosoya


Internal Medicine | 2003

Chinese Herbs and Bone Disease

Junichi Hoshino; Yoshifumi Ubara; Tetsuo Tagami; Naoki Sawa; Masafumi Yokota; Hideyuki Katori; Fumi Takemoto; Yoshihisa Mikami; Shigeo Hara; Shigeko Hara

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Fumi Takemoto

Jichi Medical University

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Shigeko Hara

Otsuma Women's University

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Hideyuki Katori

Otsuma Women's University

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Hideyuki Katori

Otsuma Women's University

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Keitaro Yokoyama

Jikei University School of Medicine

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