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Biomedical subjects

K Wakasa

Publications and source records attributed to K Wakasa.

At least 145 records · Page 8Linked to original sources
PubMed1990

Benign lymphoepithelial lesion with large cysts: case report.

A case of benign lymphoepithelial lesion with two large cysts and many foci of duct dilatation is reported. Clinical features, except for absence of dry eyes, indicated the case was Sjögren's syndrome. The cysts were found in the left parotid gland of a 60-yr-old woman and were surgically removed. The size of each cyst was 20 mm in diameter and one of them was located in the lymph node. Because of the HLA-DR expression by the epithelium, the cysts are considered to have formed as a result of duct dilatation due to autoimmune response. As for one cyst, it is also possible that the pre-existing lymphoepithelial cyst might be involved in the autoimmune phenomenon because of its relation to the lymph node.

Cysts↗
PubMed1990

Regenerating nodules in hepatic cirrhosis: MR findings with pathologic correlation.

To establish clearly the pathologic basis for small low-intensity nodules seen on MR images of the cirrhotic liver, we obtained MR images in 26 patients with cirrhosis in whom partial hepatectomy for hepatoma (15 patients), laparoscopy for cirrhosis (10 patients), or autopsy (one patient) was subsequently performed. Small low-intensity nodules were seen on gradient-echo images with short TEs (10-13 msec) in 13 of the 26 patients. In 12 of these 13 patients, small low-intensity nodules appeared larger and clearer as the TE was prolonged (14-25 msec). On T2-weighted spin-echo images, small low-intensity nodules were seen in 12 of the 13 patients, but not seen as well as on gradient-echo images. Pathologic correlation in these 13 patients revealed that the nodules on the MR images corresponded to iron deposits in regenerating nodules. Small low-intensity nodules were observed only on T2-weighted spin-echo images in two of the remaining 13 patients, in whom microscopic examination of the liver revealed marked inflammatory cell infiltration in the fibrous septa and no iron deposition. We conclude that small low-intensity nodules observed on MR images are caused by iron deposits in regenerating nodules, and that gradient-echo images with short and prolonged TEs are useful to confirm the presence of iron deposits in regenerating nodules.

Adult↗
PubMed1990

Effects of the diamond grit sizes of the commercial dental diamond points on the weight-load cutting of bovine enamel and glass-ceramic Typodont teeth.

To evaluate the effect of the diamond grit size of commercial dental diamond points on the dental cutting, we conducted weight-load cutting tests on bovine enamel and glass-ceramic typodont teeth using 3 different diamond grit sizes and air-bearing and ball-bearing air-turbine driven handpieces. With the transverse load applied on the diamond point varied between 20 and 80 g, we measured rotational cutting speed and cutting volume. Generally, increases in applied load caused decreases in rotational cutting speed and increases in cutting volume. The intensity of this trend, however, differed between grit sizes. Regular grit diamond points most strongly showed this tendency, while super-fine grit diamond points were least affected. Fine grit diamond points behaved in a manner similar to regular grit points.

Animals↗
PubMed1989

[Siderotic regenerating nodules in liver cirrhosis--evaluation by gradient echo (FLASH) imaging 1.5T].

In three patients with histologically proven liver cirrhosis, a large number of small, low-intensity nodule(SLIN)s was clearly seen on gradient echo(GRE) images which are sensitive to field inhomogeneity. A histological study revealed that the SLINs corresponded to the regenerating nodules, laden with iron, of liver cirrhosis. As TE was prolonged, the SLINs increased in size in all three cases and fused with each other in one of three cases on GRE images. This phenomenon suggests that the magnetic susceptibility effect due to iron included in the regenerating nodules is the cause for the regenerating nodules shown as SLINs on GRE images, and that one SLIN does not always correspond to one regenerating nodule. We conclude that GRE images should be considered important for diagnosis of regenerating nodules in liver cirrhosis.

Female↗
PubMed1989

Hepatocellular carcinoma in adenomatous hyperplasia of the liver.

A hepatocellular carcinoma (HCC) measuring 0.2 cm in diameter was found in the center of an adenomatous hyperplasia (AH) measuring 1.7 cm in diameter in a cirrhotic liver. The liver cells of the AH showed a marked fatty change and contained many Mallory bodies. The AH and HCC were studied in relation to liver cell dysplasia in 108 surgically resected livers. The AH was mainly associated with fully developed cirrhosis in 5 (71%) of the 7 cases. The liver cell dysplasia, however was accompanied largely by fibrosis and early-stage incomplete septal cirrhosis in 10 (67%) of the 15 cases. As far as the active inflammatory change was concerned, a fairly active inflammation was found in only 3 (20%) of the 15 livers with liver cell dysplasia, but in 4 (57%) of the 7 livers with AH.

Adenoma↗
PubMed1989

Studies of machinable ceramics for dental applications. 1. Color analysis.

Machinable ceramics that can be cut and even lathed have recently been developed in industry. As a first step in evaluating the feasibility of such ceramics in dentistry, eight machinable ceramics were examined for color using the Vita shade guide and a chroma-meter reflectance instrument. We discovered that the studied machinable ceramics varied significantly from the Vita shade guide by the color difference vector, delta E. These machinable ceramics appeared very white and strongly opaque due to their high brightness (L*) values. For intra-oral applications, we expect that L* values of machinable ceramics will be reduced by modification of their microstructures, including their matrix and dispersed phases, while their excellent machinability due to the cleavage of dispersed crystals should be retained.

Color↗
PubMed1989

Comparison of rotational speeds and torque properties between air-bearing and ball-bearing air-turbine handpieces.

We examined the effects of air pressure on the free-running speed of air-bearing and torque-type ball-bearing air-turbine handpieces. The air pressure for the former should be kept at a certain high level to maintain the stable super-thin air-bearing film and to provide the quasi-constant speed of around 420,000 to 480,000 rpm. On the other hand, the air pressure for the latter could be adjusted to provide some varieties of speeds, ranging from about 150,000 to 320,000 rpm. Subsequently, to compare torque properties and cutting effectiveness between these two handpieces, weight-load cutting tests were conducted, using a glass-ceramic workpiece and a commercial diamond point. It was confirmed that the air-bearing handpiece had the lower torque power but exhibited better cutting effectiveness, compared with its counterpart.

Air Pressure↗
PubMed1988

Necrosis of portal tumor embolus of hepatocellular carcinoma by lipiodol transcatheter chemo-embolization. A case report.

We describe a case of hepatocellular carcinoma in which a tumor embolus in the portal vein and 3 of 4 intrahepatic metastases were necrosed completely by Lipiodol transcatheter chemo-embolization (Lipiodol-TCE). Tumor emboli in the portal vein and intrahepatic metastases usually cannot be necrosed by conventional transcatheter chemo-embolization alone, because small nodules such as intrahepatic metastases and tumor emboli in the portal vein are supplied blood from the portal vein. However, in this case, Lipiodol-TCE was effective against tumor emboli in the portal vein and intrahepatic metastases.

Aged↗
PubMed1988

Analysis of photo-initiators in visible-light-cured dental composite resins.

Seven commercial visible-light-cured (VL) dental composite resins were analytically studied for identification of the photo-initiator consisting of photo-sensitizer and reducing agent. Gas-liquid chromatography (GC) was used for the determination of the dilute components extracted from the composite resin. Mass spectroscopy (GC-MS) was used for confirmation of the qualitative data obtained by GC. The results showed that all composite resins examined included camphorquinone (CQ) as a photo-sensitizer. The concentration of CQ in the resin phase, however, ranged from 0.17 to 1.03% w/w. The composite resin with hybrid-sized filler tended to have a higher concentration of CQ than did the micro-filled composite resin. As for the reducing agent, two out of seven brands contained dimethylaminoethyl methacrylate (DMAEMA), and one included dimethyl-p-toluidine (DMPTI). The mixing ratio between CQ and the amine in these three composite resins also varied. Another four brands did not contain either DMAEMA or DMPTI, and would utilize different reducing agents.

Chromatography, Gas↗