Search PubMed⌕ Search

Biomedical subjects

Y Amoh

Publications and source records attributed to Y Amoh.

27 records · Page 2Linked to original sources
PubMed1995

Effect of bone marrow transplantation on antiphospholipid antibody syndrome in murine lupus mice.

The (NZW x BXSB)F1 (W/BF1) mouse is known to be an animal model of systemic lupus erythematosus (SLE) and immune thrombocytopenic purpura (ITP). These mice produce not only anti-DNA antibodies but also anti-platelet antibodies, resulting in decreased platelet counts. They show a high level of proteinuria, increased white blood cell (WBC) counts, hypertension, and myocardial infarction due to the high levels of anti-cardiolipin antibodies. When W/BF1 mice (4-5 months) were lethally irradiated and then reconstituted with T cell-depleted bone marrow cells of normal BALB/c mice (8 weeks), 60% of the mice survived more than one year. The WBC and platelet counts in the mice were normalized, and the levels of anti-DNA and anti-platelet antibodies decreased. The renal dysfunction was also ameliorated as indicated by a lower level of proteinuria, lower levels of serum creatinine (S-CRTN) and blood urea nitrogen (BUN), and by improved histology. The blood pressure (BP) of the treated W/BF1 mice decreased due to the improved renal functions. In contrast to the non-treated W/BF1 mice which died of myocardial infarction or renal failure by the age of 7 months, the treated W/BF1 mice showed no evidence of myocardial infarction even one year after BMT. This was due to the lower cardiolipin levels.

Animals↗
PubMed1994

Fate of allogeneic or syngeneic cells in intravenous or portal vein injection: possible explanation for the mechanism of tolerance induction by portal vein injection.

In this report we examine the fate of donor cells injected via different routes. When PKH-26-labeled C57BL/6 (B6) spleen cells were intravenously (i.v.) injected into BALB/c mice, the donor cells were rejected within 3 days. In contrast, when the same B6 spleen cells were portal venously (p.v.) injected, they were trapped in the recipient liver. When allogeneic or syngeneic whole bone marrow cells (BMC) or cells in a hemopoietic stem cell (HSC)-enriched fraction were either i.v. or p.v. injected, the cells accumulated in the liver. The cells trapped in the liver were found to be wheat germ agglutinin (WGA)-positive HSC. When B6 thymocytes were p.v. or i.v. injected into BALB/c mice, they were rapidly rejected. When BALB/c mice were i.v. preimmunized with unlabeled B6 spleen cells, BMC or thymocytes, the p.v. or i.v. injected PKH-26-labeled B6 spleen cells were rejected rapidly (within 2 days). In contrast, when BALB/c mice were p.v. preimmunized with B6 spleen cells or BMC, the p.v. or i.v. injected PKH-26-labeled B6 spleen cells were not rejected. The cells responsible for the tolerance induction were found to be HSC trapped in the liver. Delayed-type hypersensitivity assays revealed that the tolerance could be maintained for more than 49 days by p.v. injection plus i.v. injection (at intervals of 2 weeks) of HSC. These findings indicate that HSC trapped in the liver play a crucial role in the induction and maintenance of p.v. tolerance.

Animals↗
PubMed1994

Carcinoma of the colon in children: case report and review of the Japanese literature.

A 15-year-old female presenting with anemia and positive for occult blood was diagnosed as having an adenomatous polyp with mild atypia in the cecum by colonoscopy. Microscopically, the majority of the surface of the tubulovillous adenoma was occupied by a well-differentiated adenocarcinoma, indicating that the adenoma-carcinoma sequence is involved in the development of colon cancers, even in children. Forty-three cases of proven carcinoma of the colon in Japanese children aged under 15 years are also reviewed. The majority of the patients were aged over 10. Although an emergency laparotomy was undertaken in 42.5% of these patients, the signs and symptoms observed in these children did not markedly differ from those of adults. Colon cancer should not be excluded in children only on the basis of age, and barium enema and colonoscopy should therefore be applied to pediatric patients with unexplainable bleeding and abdominal pain, especially those over 10 years of age.

Adenocarcinoma↗
PubMedDate not supplied

Struma ovarii: MR findings.

PURPOSE: The purpose of this study was to determine the MR appearance of struma ovarii correlating with the pathological features. METHOD: MR findings of two patients with struma ovarii were retrospectively reviewed and compared with the pathological findings. RESULTS: Both tumors were complex masses composed of multiple cysts and solid components. The size and signal intensity of multiple cysts varied within the tumor. Hyperintense cystic areas on T1-weighted images were thought to correspond pathologically to hemorrhagic cysts and follicles containing viscous proteinaceous colloid. Solid components had as high a signal intensity as did uterine endometrium on T2-weighted images and as intermediate a signal intensity as did uterine muscle layer on T1-weighted images. After intravenous administration of gadolinium-DTPA, the solid components showed marked contrast enhancement. There was also ascitic fluid associated with adhesion and peritoneal thickening. CONCLUSION: The characteristic MR appearance of struma ovarii is thought to be a mixed mass composed of T2-hyperintense solid components with intense contrast enhancement and multiple T1-hyperintense cystic areas suggestive of hemorrhagic degeneration and viscous proteinaceous colloid.

Adult↗
PubMedDate not supplied

Diagnostic pitfalls of MR cholangiopancreatography in the evaluation of the biliary tract and gallbladder.

Magnetic resonance (MR) cholangiopancreatography is a noninvasive imaging technique that has proved accurate in the diagnosis of biliary obstruction. However, various diagnostic pitfalls have been reported with MR cholangiopancreatography that were not encountered previously at conventional biliary imaging. These pitfalls may simulate or mask various pathologic conditions of the extrahepatic bile duct or main pancreatic duct and may be caused by a variety of factors. Because of its postprocessing nature, maximum-intensity-projection reconstruction may mask a small gallstone if the stone is surrounded by hyperintense bile and may cause false ductal disconnection or duplication when a breath hold is not performed perfectly. Extraductal factors (e.g., metallic surgical clips, intravascular metallic coils, gas in the stomach or duodenum) can cause signal loss in the adjacent part of the extrahepatic bile duct, which may in turn lead to a false-positive diagnosis of ductal narrowing or obstruction. Normal vascular structures including the right hepatic and gastroduodenal arteries can cause pseudo-obstruction of the extrahepatic bile duct by pulsatile compression. Intraductal factors (e.g., gas, hemorrhage, debris, iodinated contrast material) reduce the signal intensity of the bile, which may result in pseudo-obstruction, false filling defects, or a nonvisualized gallbladder or bile duct. Knowledge of the existence and high prevalence of these diagnostic pitfalls should help prevent misinterpretation of MR cholangiopancreatograms.

Artifacts↗
PubMedDate not supplied

Contrast-enhanced three-dimensional MR portography.

Three-dimensional (3D) magnetic resonance (MR) portography with contrast material enhancement is a fast means of evaluating the portal venous system that has some advantages over currently used modalities, such as digital subtraction angiography, helical computed tomography, ultrasonography, and nonenhanced MR angiography with time-of-flight and phase-contrast techniques. With contrast-enhanced 3D MR portography, a first-pass study of the mesenteric vasculature is performed after rapid bolus injection of gadopentetate dimeglumine; a 3D fast field echo sequence is used, which can demonstrate the intrahepatic and extrahepatic portal venous system clearly. Repeated sequences after administration of gadopentetate dimeglumine allow separate demonstration of the splanchnic arteries and portomesenteric veins. The images are reconstructed by means of maximum-intensity projection postprocessing, and a subtraction technique can be used to eliminate arterial enhancement and demonstrate portosystemic shunts. The coronal source images simultaneously demonstrate parenchymal lesions of the liver, pancreas, biliary tract, and spleen. This technique is clinically indicated in portosystemic shunt, portal vein thrombosis, hepatocellular carcinoma, pancreatobiliary tumor, hepatic vein obstruction, differentiation of splanchnic arterial from portal venous disease, and gastrointestinal hemorrhage. Its limitations include allergic reactions to contrast media, inappropriate positioning of the 3D acquisition slab, respiratory motion artifacts, and pseudodissection.

Contrast Media↗
PubMedDate not supplied

Dynamic subtraction contrast-enhanced MR angiography: technique, clinical applications, and pitfalls.

Rapid advances in techniques of contrast material-enhanced magnetic resonance (MR) angiography have enabled evaluation of the entire aorta and the main arteries. Dynamic subtraction MR angiography consists of first-pass imaging of long segments of arteries by using a three-dimensional fast field echo sequence with multiple rapid bolus injections of a small dose of gadopentetate dimeglumine. Subtraction enables clear demonstration of the enhanced vascular lumen by eliminating background signal. Improved temporal resolution and repeated sequences after gadopentetate dimeglumine administration allow demonstration of arteries and veins separately. Double subtraction postprocessing can be used to eliminate arterial enhancement in demonstration of the portal and systemic veins. Additional postprocessing can be used to demonstrate arteries in a single image in patients with aortic dissection or a prolonged circulation time. To optimize the examination, the pulse sequence, injection dose, injection rate, timing of the start of data acquisition, imaging time, breath holding, section thickness, and coil selection should be considered. This technique is flexible enough to be applied in a variety of clinical settings, including atherosclerotic occlusive disease, aneurysm of aortoiliac arteries, bypass graft, Takayasu arteritis, aortic dissection, antiphospholipid antibody syndrome, renal artery disease, pelvic vascular disease, and the portomesenteric venous system.

Contrast Media↗
PubMedDate not supplied

Comprehensive MR imaging of acute gynecologic diseases.

Rapid advances in techniques of magnetic resonance (MR) imaging have enabled diagnosis of acute gynecologic conditions, which are characterized by sudden onset of lower abdominal pain, fever, genital bleeding, intraperitoneal bleeding, or symptoms of shock. The chemical-selective fat-suppression technique not only helps establish the characteristics of lesions that contain fat components but also increases the conspicuity of inflammatory lesions. When a T2-weighted image is obtained with a very long effective echo time (>250 msec), even a small amount of ascites can be easily identified and the contrast between urine and complex fluid becomes more conspicuous. T2*-weighted images are useful for identification of hemorrhagic lesions by demonstrating deoxyhemoglobin and hemosiderin. Contrast material-enhanced dynamic subtraction MR imaging performed with a three-dimensional fast field-echo sequence and a rapid bolus injection of gadopentetate dimeglumine allows evaluation of lesion vascularity and the anatomic relationship between pelvic vessels and a lesion and allows identification of the bleeding point by demonstrating extravasation of contrast material. To optimize the MR imaging examination, attention should be given to the parameters of each pulse sequence and proper combination of the sequences.

Diagnosis, Differential↗