Biomedical subjects

K Wakasa

Publications and source records attributed to K Wakasa.

At least 127 records · Page 7Linked to original sources

PubMed1992

[Dynamic 3DFT FISP MR imaging of hepatocellular carcinoma].

Dynamic 3 dimensional Fourier transformation (3DFT) FISP MR imaging was performed in 5 patients with hepatocellular carcinoma before partial hepatectomy. Immediately after 0.1 mmol/kg of Gd-DTPA was administered intravenously, 3DFT FISP images (TR/TE/flip angle/slice thickness, 20 msec/8 msec/30 degrees/2-4 mm) were obtained every 30 seconds until 150 sec. We correlated dynamic MR images of the 5 patients with gross and microscopic findings. Some regions in the tumor corresponding to viable cells showed high intensity enhancement and other regions corresponding to necrotic regions showed no enhancement on the early phase images. We concluded that dynamic 3DFT FISP MR imaging which had good spatial resolution was useful in evaluating the vascularity of the tumor.

Aged↗

PubMed1992

[Regenerating nodules in liver cirrhosis--patho-MR-serological correlation study].

An MR study was performed in 73 clinically diagnosed cirrhotic patients to determine correlations among the demonstration of small low intensity nodules (SLINs), secondary changes due to cirrhosis, and serological data. In 32 patients, liver cirrhosis was proved histologically. SLINs were observed in 38 of the 73 patients on gradient echo (GRE) images and in 28 patients on T2-weighted SE images. Patho-MR correlation study of the liver in the 32 histologically proved cirrhotic patients revealed that SLINs were seen on GRE images only in patients with iron deposits in regenerating nodules (RNs). There was no significant correlation between secondary changes due to liver cirrhosis and the demonstration of SLINs. Serological data indicating liver cell injury and iron store in the body were significantly higher in patients with iron deposits in RNs than in those without iron deposits.

Adult↗

PubMed1992

Detection of cytomegalovirus DNA in pulmonary specimens: confirmation by in situ hybridization in two cases.

Papanicolaou stained bronchial brush and imprint pulmonary smears containing intranuclear and cytoplasmic inclusion bearing alveolar pneumocytes suggestive of cytomegalovirus infection were destained and reprocessed for in situ hybridization using a biotinylated probe for cytomegalovirus DNA. Two cases were processed in this way. A hybridization signal for viral DNA was noted in each case. However, no reddish brown staining reaction products were noted in any of the control samples. This simple and rapid nonradioactive detection system is a valuable supplement to routine pulmonary cytology for the definitive diagnosis of this virus infection, and this technique is also appropriate for retrospective study.

Cytodiagnosis↗

PubMed1992

Relationship between pathologic prognostic factors and abnormal levels of des-gamma-carboxy prothrombin and alpha-fetoprotein in hepatocellular carcinoma.

The relationship between pathologic prognostic factors and abnormal levels of des-gamma-carboxy prothrombin and alpha-fetoprotein was investigated in 42 patients with resectable hepatocellular carcinoma. The frequencies of macroscopic massive type, intrahepatic metastasis, and portal vein tumor thrombus were significantly higher in patients with positive des-gamma-carboxy prothrombin (p less than 0.05) but not with alpha-fetoprotein. Other histologic factors in tumorous and nontumorous tissues were not significantly different irrespective of the positivity of these markers. In patients with tumors not more than 6 cm in diameter, the frequency of intrahepatic metastasis was positively correlated with the positivity of des-gamma-carboxy prothrombin (p less than 0.05) and inversely with that of alpha-fetoprotein (p less than 0.05). Furthermore, intrahepatic metastasis was most frequently observed in patients with positive des-gamma-carboxy prothrombin and negative alpha-fetoprotein (eight of nine) and least frequently in cases with negative des-gamma-carboxy prothrombin and positive alpha-fetoprotein (one of eight). These findings indicated that both des-gamma-carboxy prothrombin and alpha-fetoprotein might be useful markers for the prediction of intrahepatic spread of hepatocellular carcinoma.

Biomarkers↗

PubMed1992

Characterization of inorganic fillers in visible-light-cured dental composite resins.

Inorganic fillers in seven visible-light (VL)-cured dental composite resins were examined for their size, composition, phase and content, employing the following analytical instruments. SEM observations indicated that five samples could be classified into the hybrid type while the remaining two belonged to micro-filled and sub-micron types. EDX analyses revealed that five samples contained BaO while others lacked BaO. XRD analyses showed that three were in vitreous phase, two were in the crystalline phase and two were mixtures of both. DTG thermal analyses indicated that the hybrid type composites had the higher inorganic filler content (wt%) than the composites of two other types. In conclusion, wide varieties exist in the inorganic fillers in VL-cured dental composite resins currently utilized.

Aluminum Oxide↗

PubMed1992

In-vitro and in-vivo wear profile of composite resins.

The aim of this study was to evaluate in-vitro wear by two types of slurry of 10 commercial composite resin materials (seven hybrid and three microfilled composites). There was great variation in the in-vitro wear pattern by two types of slurry. The wear rate of microfilled composites was greater than that of hybrid composites, and a negative correlation was observed between wear rate and Knoop hardness values among all materials when hydroxyapatite slurry was used. In contrast, the wear rate of hybrid composites was greater than that of microfilled composites when abraded by green carborundum slurry. These abraded surfaces were compared with SEM micrographs of in-vivo composites surface after 4 years of service. The profile of in-vivo wear surfaces was found to be similar to that of in-vitro wear surfaces abraded with hydroxyapatite slurry.

Composite Resins↗

PubMed1991

Limitation of transcatheter arterial chemoembolization using iodized oil for small hepatocellular carcinoma. A study in resected cases.

The radiologic and histologic findings are presented of the resection of 14 small hepatocellular carcinomas (HCC), less than 2 cm in maximum diameter, after transcatheter arterial chemoembolization (TCE) using iodized oil. The effect of TCE on small HCC depended on the morphologic type of the tumors. When no extracapsular invasion of tumor cells occurred, TCE was extremely effective against encapsulated tumors. However, in nine of the 14 resected specimens, viable tumor cells remained in or around the tumor. The authors suggest that small HCC are not always curable with TCE alone and that a multi-disciplinary approach is necessary for patients with small HCC.

Aged↗

PubMed1991

Histochemistry of tartrate-resistant acid phosphatase and carbonic anhydrase isoenzyme II in osteoclast-like giant cells in bone tumours.

Using routinely processed, paraffin-embedded tissue specimens, osteoclast-like giant cells in giant cell tumour of bone (GCT), chondroblastoma, osteoblastoma and osteoblastic osteosarcoma were examined histochemically for osteoclast-specific enzymes tartrate-resistant acid phosphatase (TRAP) and carbonic anhydrase isoenzyme II (CA-II). Osteoclast-like giant cells and some mononuclear cells possessed TRAP activity. These were further classified with respect to CA-II immunoreactivity, i.e. cells with CA-II were seen in GCT and chondroblastoma, while those in osteoblastoma and osteoblastic osteosarcoma were negative for CA-II. All the cellular components in malignant fibrous histiocytoma and various extraosseous inflammatory lesions including malignant giant cells and macrophage polykaryons were negative for both TRAP and CA-II. These results indicate that osteoclast-like giant cells in GCT, chondroblastoma, osteoblastoma and osteoblastic osteosarcoma are all osteoclasts and generated by fusion of mononuclear cells with the same histochemical characteristics as osteoclast-like giant cells. The difference in CA-II immunoreactivity suggests the functional or maturational difference between osteoclast-like giant cells in GCT and chondroblastoma and those in osteoblastoma and osteosarcoma.

Acid Phosphatase↗

PubMed1991

Laser microdissection and single unique primer PCR allow generation of regional chromosome DNA clones from a single human chromosome.

We have developed an argon laser chromosome microdissection technique in conjunction with a polymerase chain reaction (PCR) approach to directly amplify microdissected chromosomes. The single 22-mer primer used in PCR, although unique in sequence (5'-TAGATCTGA-TATCTGAATTCCC-3'), randomly primed and amplified any target DNA. These methods were applied to the distal half of the short arm of human chromosome 4 containing the Huntington disease (HD) locus. Forty-four percent of representative clones from this library identify single-copy DNA sequences. This calculation suggests that the resulting chromosome-specific DNA library contains approximately 600 nonoverlapping sequences with an average size 350 bp at an average spacing of 30 kbp along chromosome 4. This microdissection and PCR cloning procedure is a simple and general approach for constructing a chromosome region-specific DNA library from a single metaphase spread.

Base Sequence↗

PubMed1991

Cutting effectiveness and wear of carbide burs on eight machinable ceramics and bovine dentin.

As a first approach in evaluating the feasibility of industrial machinable ceramics in dentistry, we performed weight-load-cutting tests on eight machinable ceramics and bovine dentin, using #1557 carbide burs driven by an air-turbine handpiece. While the transverse load applied to the bur was cyclically varied between 20 and 80 g, we measured the cutting speed (i.e., the steady-state handpiece speed during cutting) and the cutting volume. The greater the applied load, the more the cutting speed decreased and the cutting volume increased. The degree of this trend, however, differed among the workpieces. When dentin and mica-based glass ceramics were being cut, the cutting speed was moderately reduced, the cutting effectiveness of the bur remained high, and the wear of the bur was small. When other ceramics--such as AIN-based, Si3N4-based, and CaO.SiO2-based ceramics--were being cut, however, the cutting speed was less diminished, and the cutting efficiency of the bur was smaller and decreased rapidly, along with extensive wear of the bur. We speculate that mica-based glass ceramics could be used as the substitute for dentin in the pre-clinical cutting exercise, and that another potential use of machinable ceramics examined might be in the production of future machined dental prostheses.

Animals↗

PubMed1991

Residual monomers (TEGDMA and Bis-GMA) of a set visible-light-cured dental composite resin when immersed in water.

Rods of a visible-light-cured dental composite resin were photo-polymerized and immersed in water at 37 degrees C for 7 days. The residual monomers (TEGDMA and Bis-GMA) trapped in the set composite and those eluted into water were analysed by gas-liquid chromatography. It became evident that minor amounts of the residual monomers dissolved in water, but that most residual monomers remained in the set composite. Extension of the irradiation period contributed to the significant reduction in the residual monomer level and its elution into water.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1991

Refractive-index-adjustable fillers for visible-light-cured dental resin composites: preparation of TiO2-SiO2 glass powder by the sol-gel process.

New fillers have been prepared for visible-light-cured (VL) dental resin composites with the refractive index adjustable to that of the resin phase. These SiO2 glass powders containing TiO2 up to 20 wt% were formed by heating to 1000 degrees C ground gels made from a mixture of Ti[OCH(CH3)2]4 and Si(OC2H5)4. With increasing TiO2 content, the refractive index of the prepared power increased linearly, while the optical transmittance at 467 nm decreased linearly. The experimentally formulated VL-cured resin composites, consisting of (TEGDMA and Bis-GMA) monomer mixture and TiO2-SiO2 glass filler, had greater transmittance when the refractive index of the filler matched that of the monomer mixture, resulting in a greater degree of monomer conversion upon irradiation with VL.

1-Propanol↗

PubMed1990

Massive pulmonary tumor emboli in osteosarcoma. Occult and fatal complication.

The lung is the most frequent site of metastasis in osteosarcoma, but extensive intraluminal tumor growth in pulmonary arteries is rare. Two patients with osteosarcoma in whom the tumors grew in the pulmonary artery and caused massive pulmonary emboli are reported. Histologically the tumor emboli were myxoid and different from the primary lesion and the other metastases, which were osteoblastic in one case and chondroblastic in another case. In both cases the pulmonary tumor emboli were the cause of death.

Adolescent↗

PubMed1990

Effect of transcatheter arterial embolization on the boundary architecture of hepatocellular carcinoma.

Daughter nodules and intrahepatic metastases are resistant to conventional transcatheter arterial embolization therapy. To clarify the mechanism of this resistance, the boundaries of hepatocellular carcinomas and their relationship to the blood supply were studied. The boundaries of the hepatocellular carcinomas studied were classified as one of five types: encapsulated, granulation, stromal, replacing, or sinusoidal. The granulation and stromal types had a capsule-like structure, but lacked the hyalinization which is the hallmark of a true tumor capsule. The granulation and stromal types could also be differentiated from the encapsulated type because of their different blood supplies and the differing effects of transcatheter arterial embolization. When barium sulfate was infused into the portal vein, it did not enter into encapsulated tumors, but it entered granulation and stromal type tumors. Small nodules such as daughter nodules and intrahepatic metastases do not have capsules, and so have a blood supply that makes them resistant to conventional transcatheter arterial embolization therapy.

Autopsy↗

PubMed1990

Phenotypic characteristics of tumour-infiltrating lymphocytes in human oesophageal cancer tissues defined by quantitative two-colour analysis with flow-cytometry.

Phenotypic subpopulations of tumour-infiltrating lymphocytes (TIL) separated from human oesophageal cancer tissues were defined by quantitative two-colour analysis with flow-cytometry (FACScan), and their characteristics were investigated by comparison with peripheral blood lymphocytes (PBL) and intra-oesophageal lymphocytes from noncancerous tissue (IEL) as the controls. Fifteen patients (13 males and 2 females) with squamous cell carcinoma of the oesophagus were entered into the study. Lymphocytes were analyzed by FACScan and the frequencies of the subpopulations were determined using monoclonal antibodies for surface markers. Single colour analysis revealed a predominance of T cells among TIL and a significant reduction of natural killer (NK) cells compared with the controls. Two-colour analysis showed that CD4+ Leu8- (helper T cells) and CD8+ CD11b- (cytotoxic T cells) were significantly increased among TIL when compared with the controls. This significant increase of both helper and cytotoxic T cells, which are indispensable components of cellular immunity, strongly implies that TIL are performing a role in the expression of antigen-specific cellular immunity against the tumours. This is the first report of a phenotypic study of human oesophageal cancer that clearly indicates the significance of the TIL and suggests their potential for use as a source of adoptive immunotherapy.

Adult↗

PubMed1990

Principal lymphocyte subpopulation in local host response to human oesophageal cancer.

We investigated what subpopulations of tumour-infiltrating lymphocytes (TIL) play a key role in in vivo function and what determines the degree of local host response represented by lymphocyte infiltration in human oesophageal cancer. We examined the increased subpopulation of TIL in "good responders" (GR) (patients with intensively TIL infiltrated tumours) when compared with "poor responders" (PR) (patients with weakly TIL infiltrated tumours). The frequency of each subpopulation was determined by quantitative flow-cytometric measurement on TIL separated from fresh tumours. Of TIL in GR, the frequency of CD3+ cells increased significantly (P less than 0.05) but the frequencies of CD16+, Leu7-, and CD16+ Leu7- cells were low and did not increase significantly compared with those in PR. With respect to T-cell subsets of TIL in GR, the frequency of CD8+ cells was significantly higher than that in PR (P less than 0.01), and CD4+/CD8+ ratio was lower than that in PR (P less than 0.025). On two-colour analyses, most of CD8+ cells (cytotoxic/suppressor T-cells: Tc/s) did not co-express CD11b and the frequency of CD8+ CD11b- cells (cytotoxic T-cell: Tc) increased significantly compared with that in PR. Clinicopathological and phenotypic analysis of peripheral blood lymphocytes revealed that there are no major differences in general immunocompetence between GR and PR. These results suggest that Tc/s, especially Tc, might play a key role in local host response. They also suggest that not only the general immune status of the host but also the identification of class I major histocompatibility complex antigens by the host at the tumour site may strongly affect the degree of host response in oesophageal cancer.

Aged↗

PubMed1990

Dental cutting behaviour of mica-based and apatite-based machinable glass-ceramics.

Some recently developed industrial ceramics have excellent machinability properties. The objective of this study was to evaluate the dental cutting behaviour of two machinable glass-ceramics, mica-containing Macor-M and apatite- and diopside-containing Bioram-M, and to compare them with the cutting behaviour of a composite resin typodont tooth enamel and bovine enamel. Weight-load cutting tests were conducted, using a diamond point driven by an air-turbine handpiece, While the transverse load applied on the point was varied, the handpiece speed during cutting and the volume of removal upon cutting were measured. In general, an increase in the applied load caused a decrease in cutting speed and an increase in cutting volume. However, the intensity of this trend was found to differ between four workpieces. Cutting Macor-M resulted in the second-most reduced cutting speed and the maximum cutting volume. Cutting Bioram-M gave the least reduced cutting speed and the minimum cutting volume. It was suggested that two machinable glass-ceramics could be employed as typodont teeth. This study may also contribute to the development of new restorative dental ceramic materials, prepared by machining.

Aluminum Silicates↗

PubMed1990

Studies on fracture toughness of dental ceramics.

One important mechanical property of dental ceramics is fracture toughness, KIC, which represents the serviceability in the oral cavity, such as the resistance to marginal fracture. KIC values of several dental ceramics, natural tooth enamel and industrial ceramics were examined by use of the indentation microfracture (IM) method. This technique was based on the series of radial cracks emanating from the corners of the Vickers indentation. It was observed that appropriate load levels should be selected on each specimen to induce radial/median cracks. For feldspatic dental porcelains, larger loads of 10, 20 and 30 kg were needed to determine their KIC values in the range 1.5-2.1 MN.m-3/2. For natural tooth enamel and a new apatite-based castable glass-ceramic, a smaller force of 1 kg was sufficient to decide the respective KIC values of about 0.9 and 1.8 MN.m-3/2. The KIC values of most dental ceramics examined were slightly higher than that of soda lime glass, but less than one-third that of zirconia. It was confirmed that the IM method is simple and cost-effective for evaluation of KIC of dental ceramics.

Aluminum Silicates↗