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Dive into the research topics where Wakako Yamamoto is active.

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Featured researches published by Wakako Yamamoto.


Annals of Nuclear Medicine | 2003

Comparison of myocardial fatty acid metabolism with left ventricular function and perfusion in cardiomyopathies: by 123 I-BMIPP SPECT and 99m Tc-tetrofosmin electrocardiographically gated SPECT

Chunlei Zhao; Noriyuki Shuke; Atsutaka Okizaki; Wakako Yamamoto; Junichi Sato; Yukio Ishikawa; Takafumi Ohta; Naoyuki Hasebe; Kenjiro Kikuchi; Tamio Aburano

Objective: To investigate myocardial fatty acid metabolism and its relationship with left ventricular (LV) function and perfusion in hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM).Methods: Thirty-nine patients with cardiomyopathies (58±14 y), comprising 15 DCM and 24 HCM, and 9 age-matched healthy controls were studied with123I-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) and99mTc-tetrofosmin (TF) electrocardiographically gated SPECT. As parameters of myocardial fatty acid metabolism, the heart-to-mediastinum ratio (H/M) and global washout of BMIPP were calculated from early and delayed planar images, while regional BMIPP uptake and washout were calculated from SPECT. In TF study, the H/M (H/M-TF) and LV ejection fraction (LVEF) were calculated as global parameters of perfusion and function, while regional TF uptake and wall thickening index were calculated as regional parameters of perfusion and function using the Quantitative Gated SPECT software. The differences in the parameters and the correlations between the parameters from the 2 studies were investigated by one-way ANOVA and multiple linear regression analysis.Results: BMIPP uptake was decreased (p<0.05), and its washout was increased (p<0.05) in DCM and HCM. In multiple linear regression analysis, global BMIPP parameters showed no significant correlation with LVEF (p>0.05), but showed a significant correlation with H/M-TF (p<0.05) in DCM and HCM. According to the partial correlation coefficient, early H/M was the only significant factor (p<0.05) for predicting H/M-TF in DCM and HCM. Multiple linear regression analysis on regional parameters showed regional BMIPP parameters had no correlation with regional function (p>0.05) but had a significant correlation with regional perfusion (p<0.0001) in DCM. In HCM, regional BMIPP parameters showed significant multiple linear correlations with both regional function (p<0.005) and perfusion (p<0.0001). According to the partial correlation coefficients, delayed regional BMIPP uptake was the most significant factor for predicting regional function in HCM, while early regional BMIPP uptake was the only or the most significant factor for predicting regional perfusion in DCM and HCM, respectively.Conclusion: In DCM, BMIPP uptake and washout could not reflect LV function. In HCM, regional delayed BMIPP uptake might be useful for evaluating regional function. In DCM and HCM, early BMIPP uptake might be largely determined by myocardial perfusion.


Japanese Journal of Cancer Research | 1998

Rhenium‐186‐mercaptoacetyltriglycine‐labeled Monoclonal Antibody for Radioimmunotherapy: In vitro Assessment, in vivo Kinetics and Dosimetry in Tumor‐bearing Nude Mice

Seigo Kinuya; Kunihiko Yokoyama; Harunobu Tega; Takashi Hiramatsu; Shota Konishi; Wakako Yamamoto; Noriyuki Shuke; Tamio Aburano; Naoto Watanabe; Terahiko Takayama; Takatoshi Michigishi; Norihisa Tonami

Stability and immunoreactivity of 186Re‐labeled monoclonal antibody were examined, and its in vivo kinetics was investigated in tumor‐bearing Balb/c nu/nu female mice to assess the feasibility of using it in radioimmunotherapy (RIT). A murine IgG1, A7, against a 45 kD glycoprotein in human colon cancer was radiolabeled with 186Re by using a chelating method with a mercaptoacetyltriglycine (MAG3). 186Re‐MAG3 complex was conjugated to A7 after esterification of 186Re‐MAG3 with tetrafluorophenol (TFP). The efficiency of 186Re‐MAG3‐TFP production and the labeling efficiency of A7 were 51–59% and 57–60%, respectively. Immunoreactivity of purified 186Re‐MAG3‐A7 was 68.2% at infinite antigen excess. In 0.9% NaCl at 4°C, the radioactivity (12.7 MBq/mg, 3.55 MBq/ml) dissociated with time from 186Re‐MAG3‐A7 as a small molecular weight moiety because of autoradiolysis. The addition of ascorbic acid, 5 mg/ml, as a radioprotectant or storage at –80°C could effectively prevent the radiolysis of 186Re‐MAG3‐A7 for 7 days. Immunoreactivity of 186Re‐MAG3‐A7, 6.70 MBq/mg (6.66 MBq/ml), stored in the presence of ascorbic acid was well retained up to 8 days after the preparation. In colon cancer xenografted mice, 31.0% of the injected dose/g of 186Re‐MAG3‐A7 had accumulated in the tumors at 24 h postinjection. Estimated radiation dose to tumors was 14.9 cGy/37 kBq up to 8 days postinjection which was 12‐fold greater than the whole‐body radiation dose. These in vivo characteristics were superior to those of A7 labeled with radioiodine, affording greater therapeutic ratios than 131I‐A7. Because of the better image quality of 186Re‐MAG3‐A7 as well as more favorable dosimetry, 186Re‐MAG3‐A7 would be a better choice for RIT of colon cancer than 131I‐A7. These results indicated the feasibility of RIT with 186Re‐MAG3‐A7, though the prevention of radiolysis of the labeled antibody should be considered.


Annals of Nuclear Medicine | 2000

Protein-less into retroperitoneal lymphangioma: Demonstration by lymphoscintigraphy and blood-pool scintigraphy with Tc-99m-human serum albumin

Atsutaka Okizaki; Noriyuki Shuke; Wakako Yamamoto; Kouki Usui; Shin Kovano; Naoyuki Miyokawa; Yoshihiko Tokusashi; Tamio Aburano

A rats, benign congenital lymphangioma has been reported to ocour frequently in the neck and axilla, but rarely in the retroperitoneal space. We report a case of a retroperitoneal lymphangioma associated with hypoproteinemia caused by protein-loss into the tumor. In this case, lympho-scintigraphy with subcutaneously injected Tc-99m-human serum albumin (HSA) disclosed the communication between the tumor and the lymphatic system, and sequential abdominal scintigraphy with intravenously injected Tc-99m-HSA revealed the protein loss into the tumor. Abdominal scintigraphy with Tc-99m-HSA injected intravenously or subcutaneously is occasionally useful for determining the etiology of hypoproteinemia.


Clinical Nuclear Medicine | 2001

Intense uptake of technetium-99m tetrofosmin by lactating breasts.

Wakako Yamamoto; Noriyuki Shuke; Koki Usui; Tamio Aburano; Naofumi Takehara; Kenjiro Kikuchi

A 38-year-old woman was hospitalized for syncope. Because an electrocardiogram showed intermittent ventricular tachycardia, myocardial perfusion imaging with technetium-99m tetrofosmin was performed to screen for coronary artery disease. Left ventricular myocardial perfusion was within normal limits. However, symmetric bilateral breast uptake was noted. According to her clinical history, she had been breast-feeding her 5-month-old infant until this admission. In these circumstances, the breast uptake of Tc-99m tetrofosmin was thought to be physiologic and related to lactation.


Clinical Nuclear Medicine | 2000

Scintigraphic findings of tibial adamantinoma on a three-phase bone scan.

Koki Usui; Wakako Yamamoto; Noriyuki Shuke; Tamio Aburano; Yasuhiro Yamanaka; Yoshihiko Tokusashi; Naoyuki Miyokawa

A case of adamantinoma is reported in which three-phase radionuclide bone imaging was performed to characterize the lesion. A 16-year-old boy was hospitalized with left lower leg pain and swelling. On a plain radiograph, an osteolytic lesion was shown in the left tibia. A three-phase bone scan with Tc-99m MDP showed increased blood flow, increased blood pooling, and localized increased accumulation in the area corresponding to the lesion seen on the radiograph, in respective phases. Surgical biopsy revealed that the lesion was an adamantinoma. Adamantinoma should be included in the gamut of positive findings on three-phase bone imaging.


Clinical Nuclear Medicine | 1999

Ruptured Lymphocele as a Cause of Chylous Ascites: Demonstration by Lymphoscintigraphy

Yuji Seo; Noriyuki Shuke; Wakako Yamamoto; Koki Usui; Tamio Aburano

A 20-year-old woman who reported progressive abdominal distention was admitted to the hospital. CTs of the abdomen and pelvis showed a large amount of ascites, soft tissue density masses in the paraaortic region, and a cystic mass in the pelvis that was thought to be an ovarian tumor. Because the ascites were chylous in nature by abdominal paracentesis, lymphoscintigraphy was performed by injecting Tc-99m human serum albumin subcutaneously into the webbing between the first and second toes. Serial whole-body images suggested that the paraaortic and the cystic masses were lymphoceles extending from the pelvis to the paraaortic region. A gradual increase in abdominal activity was also observed, indicating leakage of lymph into the peritoneal cavity. On laparoscopy, normal ovaries were observed and a fluid leak was located in the pelvic cystic mass. Based on these findings, a ruptured lymphocele was thought to be the cause of the chylous ascites.


Nuclear Medicine and Biology | 1997

Short-period-induced hypertension could improve tumor-to-nontumor ratios of radiolabeled monoclonal antibody

Seigo Kinuya; Kunihiko Yokoyama; Wakako Yamamoto; Shota Konishi; Noriyuki Shuke; Tamio Aburano; Naoto Watanabe; Teruhiko Takayama; Takatoshi Michigishi; Norihisa Tonami

This study was undertaken to find optimum period of hypertensive treatment for the improvement of tumor targeting of 111In-labeled monoclonal antibody. Angiotensin II was infused into tumor-bearing mice at an infusion rate of 2.0 micrograms/kg/min determined by the dose-finding study. The infusion was continued for up to 72 h, and biodistribution of 111In-DTPA-A7, a murine IgG1, was observed 72 h postinjection. Tumor-to-nontumor ratios were best improved with the infusion for 0.5-3 h. However, with the longer infusion, the effect deteriorated by the increase of nontumor uptakes, and body-weight loss became remarkable. It could be concluded that hypertensive treatment for a short period could be safely performed to benefit targeting of radiolabeled monoclonal antibody.


Annals of Nuclear Medicine | 1997

Discordant splenic uptake of Tc-99m colloid and Tc-99m denatured RBC in candidiasis-endocrinopathy syndrome.

Tamio Aburano; Ryuji Katada; Noriyuki Shuke; Wakako Yamamoto; Takako Kawakami; Isao Makino; Junichi Sato; Yukio Ishikawa

We report discordant splenic uptake of Tc-99m colloid and Tc-99m heat-denatured red blood cells (RBC) which occurred in a 21-year-old female with candidiasis-endocrinopathy syndrome. Tc-99m colloid liver-spleen imaging showed no splenic uptake, suggesting the presence of functional asplenia. A subsequent Tc-99m heat-denatured RBC study clearly revealed a small spleen with preserved sequestrating function. These results may demonstrate that the qualitative dissociation of splenic functions in processing colloid and denatured RBC in functional asplenia: the sequestration function remains while the reticuloendothelial system is impaired.


Clinical Nuclear Medicine | 2001

Accumulation of Tc-99m HMDP in extramedullary plasmacytoma of the stomach.

Noriyuki Shuke; Atsutaka Okizaki; Wakako Yamamoto; Kouki Usui; Tamio Aburano

A case of extramedullary plasmacytoma is reported as a rare cause of stomach uptake of bone tracer. A 48-year-old woman, who was thought to have a submucosal tumor of the stomach based on endoscopic findings, underwent bone scintigraphy with Tc-99m HMDP that showed extraosseous uptake in the left upper abdomen. A double-contrast upper gastrointestinal barium examination and abdominal computed tomography revealed a large tumor of the stomach with dense calcifications, which corresponded to the accumulation of Tc-99m HMDP. Biopsy of the tumor removed via endoscopy revealed extramedullary plasmacytoma of the stomach.


Annals of Nuclear Medicine | 1999

Sub-super bone scan caused by bone marrow involvement of prostate cancer.

Yuji Seo; Noriyuki Shuke; Wakako Yamamoto; Kouki Usui; Tamio Aburano

A 67-year-old man presented with malaise and marked anemia. A diagnostic workup revealed severe pancytopenia on a complete blood count and diffuse sclerotic change in the axial skeleton on a plain abdominal radiograph. Bone metastases being suspected from these findings, bone scintigraphy was performed. The bone scan demonstrated uniformly increased skeletal activity with faint soft-tissue activity. The findings of the bone scan, however, appeared atypical of the super scan caused by diffuse bone metastases, without any decrease in radioactivities of the appendicular skeleton and kidneys. Bone marrow scintigraphy with In-111 chloride demonstrated central marrow failure and peripheral expansion, which indicated the possibility of myelophthisis. The patient underwent bone marrow biopsy, which revealed replacement of the bone marrow by metastatic adenocarcinoma. Further examinations detected the primary lesion in the prostate. In this case, the findings of the bone scan were insufficient for the super scan, and might be categorized as a sub-super scan. It would be important to recognize this incomplete form of super scan as a rare scintigraphic pattern of diffuse bone marrow metastases.

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Noriyuki Shuke

Asahikawa Medical College

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Junichi Sato

Asahikawa Medical College

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Kenjiro Kikuchi

Asahikawa Medical College

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Chunlei Zhao

Asahikawa Medical College

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Kouki Usui

Asahikawa Medical College

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Yukio Ishikawa

Asahikawa Medical College

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Shigeo Kaneko

Asahikawa Medical College

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