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Biomedical subjects

K Wakasa

Publications and source records attributed to K Wakasa.

At least 91 records · Page 5Linked to original sources
PubMed1997

Decomposition analysis of binary polyfunctional urethane monomer mixtures.

Thermal decomposition in three binary monomer mixture systems containing an experimentally synthesized monomer (EXP3) and a commercial polyfunctional urethane monomer (U-4TXA) was examined in terms of differential thermal analysis (DTA) and simultaneous thermogravimetry (TG) analysis when a sample was heated to 800 degrees C. The binary EXP3/U-4TXA monomer mixtures were visible light-cured (VLC) resins which included CQ (camphorquinone=0.5 wt%) and DMAEMA (dimethylaminoethyl methacrylate=0.5 wt%) as the photoinitiator. Their DTA curves showed that thermal decomposition initiated at around 300 degrees C and finished at around 500 degrees C. TG curves showed complete weight loss at 800 degrees C during thermally induced decomposition: the decomposition reaction at weight losses of 5 to 50% was calculated from the slope of the (1/T) versus log10(Hr) diagram, because the exothermic decomposition temperature shown on DTA curves increased with increasing heating rate from 2 to 20 degrees C/min. Thermal decomposition analysis showed that a decomposition with weight change had exothermic heats ranging from 0.38 to 1.07 kJ/g for the EXP U1 mixture, 1.06 to 1.76 kJ/g for EXP U2 and 1.74 to 2.02 kJ/g for EXP U3. Activation energy ranged from 1.42 to 1.89 kJ/mol at weight losses of 5 to 50% in the three binary EXP3/U-4TXA monomer mixture systems.

Journal Article↗
PubMed1997

Dental application of polyfunctional urethane comonomers to composite resin veneering materials.

Urethane monomer/diluent monomer mixtures were used in dental composite resin veneering materials filled with various ratios of powder (filler)/liquid (comonomer), P/L. Hardness values of unfilled resins containing benzoyl peroxide only (BP0; 0.5 wt%), and filled resins (included trimethylol propane trimethacrylate (TMPT) composite filler) were tested. Significant increases in hardness were obtained with the use of TMPT composite filler in the resins. Also, their modulus values measured by bend test showed an increasing trend, compared to a commercial composite resin veneering material (a control sample; CONT) with a lower filler content (50 wt%). The DME-DPMDC/HPDM comonomer (dimethacryloxyethyl diphenylmethane-4,4'-dicarbamate/hydroxypropyl dimethacrylate), which showed a smaller fraction of surface porosity, gave greater mechanical strength values at P/L ratios of 0.55 (17.8 wt% filler content) to 1.20 (27.3 wt%) than a CONT resin. The coefficient of thermal expansion was smaller in urethane-based filling materials than a CONT resin. Also, greater activation energy of thermal decomposition was observed in the resin samples with P/L ratio 0.75 to 1.20 than in a CONT resin. Thermally-induced decomposition occurred with smaller weight loss in the experimental filled resins than in a CONT resin.

Journal Article↗
PubMed1997

Dental application of binary urethane monomer mixtures:strengthened resin matrix.

The strengthened resin matrices in six experimental binary visible light-cured (VLC) urethane monomer mixtures were examined in terms of mechanical strength. A 60 wt% bis-GMA/40 wt% binary monomer mixture was used as a control sample. A dry state (1 day in air at 37 degrees C) and a wet state by immersion in distilled water (7 and 30 days at 37 degrees C) were investigated. The compressive strength and diametral tensile strength of urethane monomer samples had values equivalent to, or greater than those of a control sample in the dry state, but had increased values in the wet state. The nano-indentation hardness values in experimental urethane monomer mixtures were greater than that in a control sample in the dry state, showing that immersion in water gave increased strength (maximum increase was about 2.5 times) in six binary urethane monomer mixtures. The compressive strength of the samples in the dry and wet states exhibited linearly increasing elastic modulus values for the resin matrix in the range about 50 to 2600 MPa. The toughened resin matrix had smaller amounts of residual monomer in the urethane monomer mixtures (0.41 to 5.03 wt%) compared with that of the binary 60bis-GMA/40TEGDMA mixture (0.71 to 6.26 wt%). This study has revealed that resin matrices are strengthened by the use of four-functional urethane monomers in experimental binary urethane monomer mixtures.

Journal Article↗
PubMed1997

The structures of integration sites in transgenic rice.

Extensive genomic sequencing and sequence motif analysis have been conducted over the integration sites of two transgenic rice plants, #478 and #559, carrying the luciferase gene and/or hygromycin phosphotransferase gene. The transgenes reside in a region with inverted structure and a large duplication of rice genome over 2 kb. Integration was found at the AT-rich region and/or at the repetitive sequence region, including a SAR-like structure, retrotransposon and telomere repeats. The presence of a patch of sequence homology between plasmid and target DNA, and a small region of duplication involving the target DNA around the recombination site, implicated illegitimate recombination in the process of gene integration. Massive rearrangement of genomic DNA including deletion or translocation was also observed at the integration site and the flanking region of the transgene. The recognition sites of DNA topoisomerases I or II were observed in the rearranged sequences. Since only three junctions of transgenic rice were implicated in the illegitimate recombination and extensive rearrangement of the rice genome, rice protoplasts may be active in this process.

Amino Acid Sequence↗
PubMed1997

Early hepatocellular carcinoma macroscopically resembling adenomatous hyperplasia: pathological resemblance to carcinoma-in-situ.

The pathological features of 11 nodules of early hepatocellular carcinoma (EHCC) were studied. Their macroscopic features resembled those of adenomatous hyperplasia and differed from those of advanced hepatocellular carcinomas (AHCC). The EHCC extended along the hepatic lobular structure and lacked expansive growth. The endothelial cells in the sinusoids of EHCC did not react to Ulex europaeus agglutinin 1 (UEA1) like adenomatous hyperplasia or other liver parenchyma, whereas the endothelial cells in the AHCC did react to UEA1. Immunohistochemically, CD68-positive Kupffer cells were noted in the sinusoids of EHCC, whereas in the AHCC Kupffer cells were not seen. Tumor emboli in the portal vein and intrahepatic metastases were not identified in EHCC, which seemed to be carcinoma-in-situ or a microinvasive stage of hepatocarcinogenesis.

Adenoma↗
PubMed1997

Analysis of hyperplastic foci in livers with hepatocellular carcinomas by flow cytometry and AgNOR staining.

The phase S ratio in cell cycles were analyzed in livers with hyperplastic foci (HPF) and in livers without HPF by nuclear DNA determinations using flow cytometry, and by staining with argyrophilic proteins of the nucleolar organizer region (AgNOR). Flow cytometric analysis was done on 50 fresh frozen specimens of livers resected from 50 patients with hepatocellular carcinoma (HCC). Paraffin sections from the same patients were analyzed using AgNOR staining. There were 25 cases each with and without HPF. We examined the stage of fibrosis and the grade of inflammatory activity according to the modified Scheuer and Desmet scale. The incidence of HCC recurrence among these patients was also studied. The average phase S ratio of the livers of the patients with HPF was 6.5 +/- 3.2%, and that of the livers of the patients without HPF was 4.0 +/- 2.5%. The ratio differed significantly between the two groups (P < 0.01). The average AgNOR score for HPF lesions of the HPF-positive cases was 1.60 +/- 0.34, that for non-HPF lesions in the HPF-positive cases was 1.29 +/- 0.12, and that for the HPF-negative cases was 1.19 +/- 0.14. Significant differences were found between the average AgNOR scores for HPF lesions of the HPF-positive cases and the non-HPF lesions of the HPF-positive cases (P < 0.01), as well as between the non-HPF lesions in the HPF-positive cases and the HPF-negative cases (P < 0.05). Severe fibrosis (stage 3) and cirrhosis (stage 4) were found in 76% of HPF-positive cases and 48% of HPF-negative cases. The livers of HPF-positive patients were significantly more cirrhotic than those of HPF-negative patients (P < 0.05). The association between HPF and the inflammatory grade was not significant (P > 0.05). The incidence of HCC recurrence among HPF-positive cases was significantly higher than that among the HPF-negative cases (P < 0.05). The average phase S ratio of the recurrent HPF-positive patients was 7.48 +/- 3.48%, significantly higher than that of HPF negative cases (5.57 +/- 3.06%, P < 0.05). Hyperplastic foci of the liver was shown to be a highly proliferative lesion. The proliferative activity of the non-HPF lesions in the HPF-positive patients was also higher than that of the HPF-negative patients. Hyperplastic foci tended to be present in cirrhotic livers, but it was not associated with the grade of inflammatory activity of the liver. Hyperplastic foci may represent an important predictor of recurrence after hepatic resection.

Adult↗
PubMed1997

Malignant fibrous histiocytoma of the temporal bone with endocranial extension.

Cranial malignant fibrous histiocytomas are rare tumors. Most are hypervascular, destructive masses that are similar to other malignant lesions and to malignant fibrous histiocytomas found elsewhere in the body. We describe a myxoid malignant fibrous histiocytoma of the temporal bone, possibly of dural origin, with features that more closely resembled a meningioma at CT, MR imaging, and angiography.

Adult↗
PubMed1997

A case of membranous glomerulonephritis associated with gastric cancer.

We describe a patient with gastric cancer and membranous glomerulonephritis (MGN). The patient, a 61-year-old male, was admitted to our Hospital in May, 1996, because of proteinuria and hyperlipidemia persisting for a year. Laboratory examination filled the criteria of nephrotic syndrome and renal biopsy revealed MGN of stage II. Prednisolone therapy (40 mg/day p.o.) was started, followed by a gradual decrease in proteinuria from 4.5 g/day to 0.1 g/day. Endoscopic examination was performed because of stomach-ache revealed advanced gastric cancer of Borrmann 4. Desiring for a conservative therapy, he was discharged and moved to a hospice. In literature review, MGN is the most frequent lesion among various glomerular diseases associated with malignancy, such as the lung, stomach, and colon, particularly at an elderly ages, and sometimes antedates the detection of malignancy, as in the present case. In several cases with MGN, immune-complexes composed of tumor antigens, such as carcino-embryonic antigen, and antibodies have been reported to deposit in basement membrane of glomeruli, causing MGN. In the renal and gastric cancer tissues of the present case, the presence of three novel tumor-associated antigens, Span-1, Thomsen-Friedenreich antigen (T antigen) and F1 alpha antigen, was examined, using a immuno-peroxidase method. Although none of these three antigens were immuno-stained in the renal tissue, clinical course and literature review suggest that MGN in this patient seems to be associated with gastric cancer, which may have produced MGN-causing tumor antigens other than the three antigens. It should be emphasized that malignancy should be carefully and routinely examined in patients with MGN, particularly at elderly ages.

Glomerulonephritis, Membranous↗
PubMed1996

Idiopathic portal hypertension associated with high serum titer of autoantibodies and liver dysfunction.

Idiopathic portal hypertension (IPH) is a condition marked by unexplained portal hypertension. Although a number of immunological abnormalities occur in patients with IPH, liver function is usually normal. We experienced an unusual case of IPH in a 49-year-old woman, who had pronounced splenomegaly. Laboratory data revealed pancytopenia, hypergammaglobulinemia, and liver dysfunction. Antinuclear antibodies were positive, with high titer at 1280 dilutions of sera. LE cell phenomena were also positive. Histological examination of biopsied liver showed only mild changes, but portal venous pressure was markedly elevated, at 38 cm H2O. This case was thus characterized by both a high serum titer of autoantibodies and liver dysfunction.

Autoantibodies↗
PubMed1996

Ciliated foregut cyst in cirrhotic liver.

We encountered a patient with a ciliated hepatic foregut cyst with accompanying liver cirrhosis, which was hard to distinguish from well-differentiated hepatocellular carcinoma. A lesion 2 cm in diameter was found in the subcapsular region of the medial segment of the liver. It was slightly hypoechoic on ultrasonography, of high attenuation on nonenhanced computed tomography (CT), of high intensity on T1-weighted spin echo images of magnetic resonance imaging (MRI), and of isointensity on T2-weighted spin echo images. It was not enhanced in the arterial phase images of MRI, and was shown as a complete perfusion defect on CT arterial portography. The cyst was enucleated and found to be filled with bloody mucinous fluid.

Carcinoma, Hepatocellular↗
PubMed1996

Characteristic histologic features of human hepatocellular carcinoma with mutant p53 protein.

To characterize hepatocellular carcinoma (HCC) cells with mutant (m) p53 protein histologically, we examined 68 main nodules and 20 accessory lesions of 72 patients with HCC who underwent hepatic resection between October 1990 and September 1993. Some sections were fixed in periodate-lysine-paraformaldehyde, embedded in OCT compound, and stained with the mouse monoclonal antibody PAb1801 to m-p53 protein by the immunoperoxidase technique with avidin-biotin complexes. Other sections were fixed in 20% buffered formalin, embedded in paraffin, and stained with the mouse monoclonal antibody DO-1 to m-p53 protein in the same way. Lesions in which cells had nuclei stained for m-p53 protein were defined as being positive for the protein; 25 of the 68 main nodules and 14 of the 20 accessory lesions were positive. Large main nodules were more likely to be positive than small ones. Microscopic examination showed that a larger proportion of poorly differentiated main nodules than well differentiated nodules were positive. Larger proportions of main nodules with extracapsular invasion, septa, portal thrombi, or intrahepatic metastases were positive than main nodules without these features. Accessory lesions that seemed to be metastatic were almost all positive, but few accessory lesions that seemed to be of multicentric occurrence were positive. Our results suggest that lesions with m-p53 protein had a high grade of malignancy and metastasized readily.

Adult↗
PubMed1996

Diagnosis of borderline adenomas of the stomach by endoscopic mucosal resection.

BACKGROUND AND STUDY AIMS: The correct histological diagnosis of gastric borderline adenomas is often difficult, especially in excluding malignancy, since the usual diagnostic methods, such as radiography and histological examination of forceps biopsy specimens, are of limited accuracy. The aim of this study was to retrospectively analyze the value of endoscopic mucosal resection in establishing the correct diagnosis of borderline adenomas. RESULTS: Fourteen borderline adenomas were finally diagnosed as containing early gastric cancer type IIa (well-differentiated tubular adenocarcinoma) after endoscopic mucosal resection, of the remaining 36 tubular adenomas, six represented mild dysplasia, 24 moderate dysplasia, and six severe dysplasia. Most parts of the 14 adenomas containing early gastric cancers had regions of structural atypia, and cellular atypia was moderate in all. Seven of 14 cancers were completely resected, all patients being tumor-free after a follow-up of 33-61 months. CONCLUSIONS: These results suggest that diagnosing borderline adenoma on the basis of radiographic and endoscopic-bioptic findings is generally unreliable, because biopsy specimens may not be representative of the entire lesion. Borderline adenomas of the stomach should be completely resected by endoscopic mucosal resection to obtain a final diagnosis and - depending on the size and type of the lesion - possibly also definitive treatment.

Adenoma↗
PubMed1996

3DFT-flash MR imaging of pancreatic cancer with gadopentetate dimeglumine.

PURPOSE: We evaluated the usefulness of dynamic 3-dimensional Fourier transformation (3DFT) fast low angle shot (FLASH) MR imaging using gadopentetate dimeglumine (Gd-DTPA) to assess the extent of pancreatic cancer. MATERIAL AND METHODS: Breath-hold 3DFT-FLASH MR images (20/4; 25 degrees flip angle; 7 partitions; 3-5-mm slice thickness) were obtained before the ++administration of 0.1 mmol/kg of Gd-DTPA, just after (early phase), and 1 and 2 min (late phases) after in 14 patients with pancreatic cancer. All patients underwent surgical removal or laparotomy. We compared the findings of T1-, T2-, and postcontrast T1-weighted spin-echo (conventional SE) and 3DFT-FLASH imaging with histologic or surgical findings. RESULTS: Dynamic MR images could delineate the pancreatic tumors more clearly than the conventional SE images, and were useful for diagnosing vessel invasion. The contrast-to-noise ratio between the pancreatic cancer and the surrounding pancreatic parenchyma was significantly higher with the dynamic 3DFT-FLASH image than with the conventional SE images (p<0.01). CONCLUSION: Dynamic 3DFT-FLASH MR imaging with Gd-DTPA is useful in delineating and evaluating the extent of pancreatic cancer.

Adult↗
PubMed1996

[LGL lymphoma].

We reported in this article two patients with large granular lymphocytic lymphoma (abbreviated as LGL lymphoma). One was the patient with LGL leukemia/lymphoma (patient 1) and other was the patient with NK-LGL lymphoma (patient 2). Because the gene of TCR delta was rearranged in the patient 1, the clonality of the LGL leukemia/lymphoma was confirmed. However, it is not determined yet whether the lineage of tumor cells is T cells or NK cells. The cytochemical features of the lymphoma cells of the patient 2 were studied. It was found that NK cell-derived lymphoma cells of the patient were positively stained with these two monoclonal antibodies that are reactive with T cell; one is anti-CD45RO (UCHL-1) and other is anti-CD3. Judging from the result, malignant NK-LGL cells in some patients are cytoplasmic CD3+ and UCHl-1+. It is emphasized that May-Grünwald-Giemsa stain of biopsied specimen of the lymphoma is required for making the diagnosis of LGL lymphoma.

Adult↗
PubMed1995

Serosal balls detected immunocytochemically in peritoneal lavage obtained during surgery.

Using the immunoperoxidase technique, we studied "serosal balls," which have features resembling those of cells from primary and metastatic tumors, and may thus complicate cytodiagnosis. Serosal balls were detected in 32 (18%) of 174 peritoneal washings. The balls consisted of oval clusters of cells in solid masses surrounded by flattened cells. The interior of the serosal balls was stained green with Papanicolaou method, showing the presence of homogeneous amorphous material, sometimes stained in a filamentous pattern. Almost all serosal balls were stained immunocytochemically for both keratin and vimentin. The interior was stained with antibodies against collagen types I and III. Therefore, these balls were fragments of serous membrane, and contained fibrous tissue and mesothelial cells.

Azure Stains↗
PubMed1995

Identification of the origin of double minutes in normal human cells by laser-based chromosome microdissection approach.

Single copies of tiny chromosome fragments, appearing as double minutes, were observed in a high proportion of cells from amniotic fluid cultures of two mothers undergoing prenatal testing because of advanced age. We applied a laser-based chromosome microdissection method to diagnose the origin of the double minutes. The diagnostic procedures consisted of microdissection of double minutes from a single cell, polymerase chain reaction (PCR) amplification of the dissected DNA, and subsequent fluorescence in situ hybridization (FISH) using the PCR products as a probe pool. Metaphase chromosomes from the patients' cells and from a karyotypically normal individual were probed. Using this strategy, we were able to determine that the double minutes originated from the centromere of chromosome 13 or 21 in one case, and from the chromosome 12 centromere in the other. The characterization of such double minutes helps both in the delineation of the nature of these epichromosomal bodies in normal individuals as well as in the clarification of genetic counselling issues.

Chromatin↗
PubMed1995

Heat-insoluble cryoglobulin in a patient with essential type I cryoglobulinemia and massive cryoglobulin-occlusive glomerulonephritis.

We report a case of type I essential cryoglobulinemia with massive cryoglobulin-occlusive glomerulonephritis, in which the clinical course and the physical characteristics of the cryoglobulin were unusual. Nine years before appearance of cryoglobulin, this 54-year-old man noted edema and purpura of the lower extremities. Renal biopsy performed 2 years later showed large amounts of amorphous, weakly eosinophilic, weakly periodic acid-Schiff (PAS)-positive materials occluding the glomerular capillaries. Immunostaining showed the material to be weakly immunoglobulin (Ig) G positive, and electron microscopy showed homogeneous, electron-dense deposits. Nephrotic syndrome and azotemia did not respond to steroid treatment, and dialysis was begun 5 years after the biopsy. A small amount of cryoglobulin was first detected 2 years later, 9 years after the onset of disease. The cryoglobulin had a white gelatinous appearance, was resistant to resuspension, and did not redissolve when rewarmed to 37 degrees C. Immunoelectrophoresis of the cryoglobulin, which partially dissolved at 54 degrees C, showed it to be composed of monoclonal IgG-kappa and a small amount of albumin. We consider that the unusual physical characteristics of the cryoglobulin in this case precipitated a massive cryoglobulin-occlusive glomerulonephritis, which progressed to end-stage renal failure in the absence of significant cryoglobulinemia during the initial onset of disease.

Cryoglobulinemia↗