Publications by authors named "Kokubo T"

We present a case of intrahepatic cystic cholangiocarcinoma with unusual radiologic appearance. Computed tomography, ultrasonography, and magnetic resonance imaging showed a cystic mass with thick wall, that mimicked liver abscess, and cystic or necrotic metastasis. The fluid in the cyst was not mucinous and was negative bacteriologically.

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Bioactive glass powder (AW-G) was made into a rigid compound by mixing with ammonium hydrogen phosphate and was evaluated as a bone-defect filler. The proximal metaphysis of the rat tibia was drilled and packed with (a) polymethyl-methacrylate (PMMA) bone cement, (b) AW-G powder, (c) AW-G powder with ammonium hydrogen phosphate (AW-G)-(A-P), or (d) nothing, as a control. The animals, with different implantation periods up to 24 weeks, were sacrificed and the defective sites were histologically analyzed.

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We prepared a prosthesis for the replacement of the lumbar vertebrae of sheep, using apatite- and wollastonite-containing glass-ceramic. The material is stronger than human cortical bone and has the special feature of chemical bonding to bone. Ten sheep underwent replacement of L3 and L4 vertebrae, without bone grafting.

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We successfully controlled hypertension of a 48-year-old female by embolizing metastatic pheochromocytoma of the liver. Although transarterial embolization of the hepatic artery was uneventful, the patient soon developed severe hypertension and tachycardia which were controlled medically. Symptoms subsided within 10-20 days.

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The coronary vein has few variations. We describe a case of coronary vein with an unusual course. In this case, the coronary vein entered the umbilical portion of the left portal vein directly, whereas it usually flows into the portal trunk or splenic vein.

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High-strength bioactive glass-ceramic A-W was soaked in various acellular aqueous solutions different in ion concentrations and pH. After soaking for 7 and 30 days, surface structural changes of the glass-ceramic were investigated by means of Fourier transform infrared reflection spectroscopy, thin-film x-ray diffraction, and scanning electronmicroscopic observations, in comparison with in vivo surface structural changes. So-called Tris buffer solution, pure water buffered with trishydroxymethyl-aminomethane, which had been used by various workers as a "simulated body fluid," did not reproduce the in vivo surface structural changes, i.

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The osteoconductive potential of apatite-wollastonite containing glass ceramic (A-W.GC), hydroxyapatite (HA), and alumina (AL) was quantitatively evaluated by implanting them as granules into rat tibiae. The amount of mature bone formed in contact with the ceramics varied depending on the ceramic materials; it reached a plateau earliest in A-W.

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To assess tissue changes responsible for enhancement of the meninges adjacent to meningiomas on magnetic resonance (MR) images, the authors correlated the MR imaging characteristics of meningeal lesions seen before and after administration of gadolinium diethylenetriamine-pentaacetic acid (DTPA) with the appearance of these lesions on contrast material-enhanced computed tomographic (CT) images and with histopathologic findings in four patients. Histopathologic examination of meninges showed increased loose connective tissue, hypervascularity, and dilated vessels. There was neoplastic infiltration of the dura mater in two patients but it was restricted to the immediate junction of neoplasm and dura mater, with maximum peripheral extension within 1 mm of the tumor margin.

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A case of retrocaval ureter associated with double inferior vena cava, an exceedingly rare venous anomaly, is reported. This anomaly was correctly diagnosed by CT. CT after intravenous contrast injection showed the double inferior vena cavae on both sides of the abdominal aorta and the right ureter crossing the right inferior vena cava posteriorly.

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Tl-weighted MR images of thirty-six hips in 25 patients with avascular necrosis of the femoral head were obtained two to five times during the course of 2 to 26 months. We investigated these MR images in the light of the chronological change and compared them with plain radiographs. MR images change in 16 femoral heads; in general, the abnormal low intensity area in the femoral head reduced in extent and the internal high intensity area became smaller of disappeared.

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The surface reactions of calcium phosphate ceramics have been thought to play an important role in bonding with living bone. Hydroxyapatite (HA), tricalcium phosphate (TCP), and two kinds of apatite-containing glass ceramics were immersed in three types of solutions with different chemical constituents. The first solution was a physiological saline, the second contained phosphate (PO4), and the third was a balanced salt solution consisting of calcium (Ca), magnesium (Mg), and PO4.

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Four patients with idiopathic transient osteoporosis of the hip were examined by magnetic resonance imaging (MRI). MRI clearly showed low signal intensity in the affected femoral head on T1-weighted images and high signal intensity on T2-weighted images. After regression of hip pain, MR images became normal.

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Glass-ceramic A-W, containing crystalline apatite and wollastonite in a MgO-CaO-SiO2 glassy matrix shows high bioactivity as well as high mechanical strength, but other ceramics containing the same kinds of crystalline phases in different glassy matrices do not show the same bioactivity. In order to investigate the bone-bonding mechanism of this type of glass-ceramic, surface structural changes of the glass-ceramics after exposure to simulated body fluid were analyzed with various techniques. A solution with ion concentrations which are almost equal to those of the human blood plasma was used as the simulated body fluid, instead of Tris-buffer solution hitherto used.

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The purpose of this study is to examine the formation of hydroxyapatite on the surface of glass-ceramics (chemical composition: SiO2, 34.2; P2O5, 16.3; CaO, 44.

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T1 and T2 weighted MR images were compared in 32 hips with avascular necrosis, and the difference between them was discussed. In 27 of 32 hips, abnormal low intensity area in the affected femoral head is smaller in T2 weighted images than in T1 weighted images. The area of low intensity on T1 weighted image and high on T2 weighted image might be granuloma in reactive tissue and surrounding hyperemia.

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Mechanical properties of bone implanted with a mixture of apatite-wollastonite containing glass ceramic (A-W.GC) granules and fibrin were examined by compression testing. A 1:1 mixture of A-W.

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The purpose of this study was to investigate bone formation after implantation of a mixture of apatite--wollastonite containing glass ceramic granules (A-W.GC, 220-355 microns) and fibrin glue with a low A-W.GC granular density.

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The findings of single-level dynamic CT were reviewed in 83 lesions of cavernous haemangioma, 90 lesions of hepatocellular carcinoma, 29 lesions of metastatic tumour and 10 lesions of other hepatic masses in order to see the validity of characteristic findings of hepatic cavernous haemangioma. Well-defined, dense and continuously spreading enhancement (WDCSE) being defined as follows: 1. well-defined contour of enhanced area, 2.

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Eight cases of choledochal cyst associated with biliary malignancy (gallbladder carcinoma in three and bile duct carcinoma in five) were reviewed to evaluate the roles and limitations of computed tomography (CT) (n = 8), ultrasound (US) (n = 6), cholangiography (n = 8), and angiography (n = 6). In cases of gallbladder carcinoma, both CT and US revealed mass lesions in the gallbladder consistent with cancer. CT also depicted either a mass lesion or an irregular thickened wall in all cases of bile duct carcinoma; however, US failed to demonstrate a thickened wall in one of three cases in which CT findings were positive.

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We developed a multi-purpose catheter for visceral arteriography. The outer diameter of the catheter is 5 Fr and the inner diameter admits a 3 Fr catheter. The catheter is made of soft nylon, with a shaft enforced with stainless wire mesh to improve torque transmission.

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The cytotoxicity of hydroxyapatite (HA), tricalcium phosphate (TCP), and two types of apatite-containing glass-ceramics designated A.W-GC and A.W.

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The authors retrospectively evaluated magnetic resonance (MR) images obtained at 1.5 T in 233 patients with portal hypertension and 91 subjects without it and pathologic findings in four resected spleens (one normal). Multiple, tiny (3-8 mm in diameter), low-intensity spots in the spleen were observed in 21 of 233 patients.

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Seven cases of portosystemic collateral running through the left lobe of the liver (6 in the medial segment and 1 in the lateral segment) were reported. Six cases were diagnosed by CT and/or ultrasound, and one case was confirmed by autopsy. This collateral originated from the umbilical vein recess of the left portal vein and connected with enlarged vein in front of the left lobe of the liver.

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In this study, it was found that a Ca-P layer and a Si layer were formed on the interface of the mother glass of apatite-wollastonite containing glass-ceramics (designated AW) and bone tissue. The dissolution of Si, Ca, and P from glass (MgO-CaO-SiO2-P2O5-CaF2) is necessary to form a chemical film (a Si layer and a Ca-P layer). The three kinds of glasses used were 1) a mirror surface of the mother glass (MgO 4.

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