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Biomedical subjects

Y Hata

Publications and source records attributed to Y Hata.

At least 199 records · Page 11Linked to original sources
PubMed1996

Localized malignant peritoneal mesothelioma containing rhabdoid cells.

A case is presented of localized malignant peritoneal mesothelioma appearing as a liver neoplasm. The patient underwent tumor resection but developed a recurrent growth and died 10 months after the initial surgery. The primary tumor showed sarcomatous features with rhabdoid cells. Examination revealed the presence of hyaluronic acid, co-immunoreactivity for cytokeratin epithelial membrane antigen and vimentin, cellular contacts with small desmosomes, and intracytoplasmic lumina. These findings supported the mesothelial nature of this tumor. The recurrent tumor was composed of predominantly tubulopapillary proliferation. It was concluded that the present tumor was a localized malignant mesothelioma of a biphasic type showing a predominantly sarcomatous component in the primary tumor.

Aged↗
PubMed1996

Less segregated processing of visual information in V2 than in V1 of the monkey visual cortex.

To test the possibility of cross-talk between parallel pathways dealing with different aspects of visual information such as orientation, direction of motion and colour in cortical area V2, we quantitatively analysed visual responses of 121 V2 cells recorded from anaesthetized and paralysed macaques and compared them with those of 147 V1 cells. A selectivity index of visual responses was calculated for each neuron, which was then classified as selective or not to a particular attribute of visual stimuli. Twenty-one percent of the V2 neurons had dual selectivity to both colour and direction of stimulus motion (C&D cells). In V1, only 5% of the cells were C&D cells. Thus, the proportion of C&D cells significantly increased from V1 to V2. We also carried out cross-correlation analysis of spike trains recorded simultaneously from pairs of V2 neurons or pairs of V1 neurons. In V2, correlated firings could be observed between cells with completely different optimal orientation, such as orthogonal, while it was never observed in V1. The cross-correlation analysis further indicted that functional interactions in V2 were more widespread than those in V1. These results suggest that neurons which have different functional properties become less segregated, and that functional interactions become more widespread in V2 than in V1.

Animals↗
PubMed1996

Neovascular tissue in the intertrabecular spaces in eyes with neovascular glaucoma.

AIMS/BACKGROUND: To investigate histological changes in the trabecular meshwork in eyes with neovascular glaucoma. METHODS: Light and electron microscopic studies were carried out on the trabecular meshwork of three enucleated eyes with neovascular glaucoma. The presence and distribution of factor VIII in the trabecular meshwork was assessed using the ABC method. RESULTS: Peripheral anterior synechiae covering the trabecular meshwork were detected in two eyes, which would explain the rise in intraocular pressure. In the third the angle was not completely closed by peripheral anterior synechiae. The spaces between the trabecular beams were lined by a single layer of vascular endothelium, and were filled with red blood cells in this patient. Factor VIII was positively stained in the endothelial cells, lining both these spaces and Schlemm's canal. A basal lamina and microfibrils were detected just beneath the newly formed vascular endothelial cells. CONCLUSION: The neovascular tissue found in the trabecular spaces might be one of the factors responsible for intraocular pressure elevation in eyes with neovascular glaucoma.

Adult↗
PubMed1996

Transvenous hemodynamic assessment of arteriovenous malformations and fistulas. Preliminary clinical experience in Doppler guidewire monitoring of embolotherapy.

BACKGROUND AND PURPOSE: Transvenous monitoring of blood flow through intracranial vascular malformations was performed with an intravascular Doppler guidewire to assess hemodynamic changes during endovascular embolotherapy. METHODS: Flow velocity was assessed in the intracranial venous sinuses of two patients with arteriovenous malformations and seven patients with dural arteriovenous fistulas. In all cases, the Doppler guidewire was positioned in the dural sinuses coaxially through a 2.1F microcatheter. The Doppler guidewire was then advanced to the site of arteriovenous shunting for sampling of venous average peak velocity (APV) and pulsatility index. In two cases, simultaneous feeding artery flow velocity was monitored by transcranial color-coded duplex sonography. RESULTS: Before embolotherapy, the flow pattern in the venous sinuses was pulsatile, with a mean (+/-SD) APV of 39.0 +/- 22.5 cm/s. Total or near-total embolization was achieved in six of the nine cases. After embolization, the flow pattern became less pulsatile and the APV was reduced to a mean of 21.2 +/- 14.6 cm/s (P = .0123, one-tailed paired t test). The pulsatility index was used to calculate the maximum minus the minimum peak velocity (MxPV-MnPV). This was reduced from an average of 27.0 +/- 8.7 cm/s to 13.5 +/- 8.3 cm/s after treatment (P = .0456). A parallel reduction in APV of the feeding arteries was observed with embolization. CONCLUSIONS: Preliminary clinical experience indicates that transvenous assessment of two parameters, APV and MxPV-MnPV, is useful in the hemodynamic evaluation of intracranial arteriovenous shunts. This valuable hemodynamic information may be used for objective and quantitative monitoring during embolotherapy of intracranial vascular malformations.

Adolescent↗
PubMed1996

Intraluminal tumor of the common bile duct as a metastasis of renal cell carcinoma.

A 57-year-old woman was admitted for evaluation of liver dysfunction. A physical examination revealed jaundice and a left abdominal mass, which was diagnosed as being a large renal tumor. Cholangiography showed a smooth filling defect 1 cm in diameter at the common bile duct. Left nephrectomy, and resection of the common bile duct were performed. The pathological diagnosis was metastasis of the common bile duct wall resulting from renal cell carcinoma. Metastatic common bile duct tumors are extremely rare. However, it is important to consider that this is one of the causes of obstructive jaundice.

Carcinoma, Renal Cell↗
PubMed1996

Effect of beraprost sodium (Procylin), a stable prostaglandin I2 analogue, on a dorsal skin flap model in rats.

Beraprost sodium, a chemically stable prostaglandin I2 analogue with antiplatelet vasodilator actions, was tested by comparing the extent of viability of random pattern skin flaps in control rats and rats treated with beraprost sodium. An isolated tail based 2 x 7 cm flap was constructed in 50 Sprague-Dawley rats. In group 1 (beraprost sodium treated group, n = 25) 0.015 mg beraprost sodium were injected intraperitoneally immediately after the flap had been raised. In group 2 (control group, n = 25) the animals were injected intraperitoneally with the same volume of saline immediately after the flap had been raised. At the end of the seventh day the flap survival area was documented using digital planimetry. The difference between the results showed that beraprost sodium had significantly beneficial effect on skin flap survival (p < 0.01, Welch's test).

Animals↗
PubMed1996

[University education in geriatrics. Opinions of teaching staff on undergraduate education in gerontology and geriatric medicine].

Undergraduate education in gerontology and geriatric medicine has become more important because of a progressive increase in the aged population. To assess curricula in geriatric medicine and to survey the opinions of teaching staffs as to the ideal curriculum, a questionnaire was sent to professors of gerontology and geriatric medicine at 14 medical schools. Responses were obtained from all 14 professors. In all medical schools, students are given lectures in the fifth or sixth year, or both. The total number of hours for the lectures varied from a few hours to 40 hours, and contents of the lectures varied between schools. Medical staffs pointed out that little time is allocated to geriatric medicine. They also emphasized the importance of bedside teaching.

Curriculum↗
PubMed1996

Intraindividual variations in lipoprotein (a) levels and factors related to these changes.

Lp(a) levels are genetically determined and remain stable without major changes throughout lives. However, when an individual's Lp(a) levels are observed over a one-year period, they show spontaneous variation. The rate of intraindividual variation in Lp(a) was observed in 16 patients with hypertension, hyperlipidemia and/or glucose intolerance in a chronic stable state who regularly visited the hospital clinic once a month, at least 10 times during the year, and in whom a total of 42 blood and clinical chemistry tests including serum lipids, Lp(a) and apoproteins were performed. The rate of annual intraindividual variation of Lp(a) averaged out as 16.6%. The rate was 18.8% for isoform S4 (n = 10), 18.6% for S3 (n = 3), and although small in number of subjects, other isoforms showed minor variation rates. There was a significant negative correlation between the rate of variation (y%) and LP(a) level (xmg/dl) r = -0.605, p < 0.05, y = -0.461 x +29.8). Therefore, when Lp(a) was high, the rate of variation (SD%) was low. This was consistent with the finding that the rates of variation were low for isoforms S2, S3S4 and F, whose molecular weights were low, accompanied by high Lp(a) levels. On the other hand, when the relationship between Lp(a) level and the amount of variation (SD mg/dl) was examined, there was no correlation between the two, since the amounts of variation were almost constant at a level of 3.8 mg/dl, regardless of Lp(a) level. The annual variation of Lp(a) level was found to be related to three groups of factors based on comparison of the variations among WHO phenotypes of hyperlipidemias, univariate correlation analysis with the clinical parameters tested, and multivariate analysis: the first group of factors was related to structure and metabolism of very low-density lipoprotein such as triglycerides, phospholipids, apo C-II, C-III, E, A-II and uric acid; the second group was related to thrombosis centering on platelets; and the third group involved those in the acute phase reactions represented by 1 hr and 2 hr erythrocyte sedimentation rates.

Adult↗
PubMed1996

Analysis of the hepatocyte growth factor receptor in regeneration and oncogenesis of the liver.

The c-met proto-oncogene product is the tyrosine kinase receptor for hepatocyte growth factor. To gain insights into its functions in the liver, we carried out a study of the expression and tyrosine phosphorylation status of the Met protein during hepatic regeneration and in human hepatocellular carcinomas. Following partial hepatectomy of rats, decreased expression of the proreceptor p170MET and reduced levels of tyrosine phosphorylation were seen within 12 h. These changes were still evident 7 days later. By contrast, there was no significant alteration of the Met beta subunit. The analysis of samples from 18 patients with hepatocellular carcinoma revealed that the expression of p160MET proreceptor was increased in non-cancerous areas, while that of the p145 beta MET proreceptor was significantly greater in the tumor tissue than in the non-tumor areas (p < 0.05). These findings suggest that processing of the Met proreceptor is closely associated with regeneration and carcinogenesis of the liver.

Adult↗
PubMed1996

Enhanced platelet aggregability under high shear stress after treadmill exercise in patients with effort angina.

Platelet activation induced by shear forces occurring in a stenosed coronary artery is one of the mechanisms of coronary thrombosis. We evaluated the shear-induced platelet aggregation (SIPA) dynamics in patients with effort angina during treadmill exercise. SIPA was measured by a rotational cone-plate aggregometer. SIPA was markedly increased by exercise from 71.2 +/- 8.9% to 81.9 +/- 7.6% (p < 0.01) in the patient group. Although epinephrine concentrations were elevated, its rate of increase was not correlated with that of SIPA. Yohimbine partially inhibited the exercise-induced increase in SIPA. In contrast, a significant correlation between the changing rate of plasma von Willebrand factor (vWF) larger multimers and that of SIPA (r = 0.74, p < 0.05) was observed. Exercise-augmented SIPA is probably dependent on an increase in vWF larger multimers rather than platelet alpha2-receptor activation. Prevention of the interaction between vWF and its platelet receptors may play some role in decreasing the risk of coronary thrombosis during exercise.

Adult↗
PubMed1996

Sensitive detection of oxidatively modified low density lipoprotein using a monoclonal antibody.

We have established a new method capable of measuring the very low concentrations of oxidized low density lipoprotein (OxLDL). In our previous study, we obtained a novel murine monoclonal antibody against oxidized lipoproteins (Itabe, H. et al. 1994. J. Biol. Chem. 269: 15274-15279). The epitope of this antibody resides in oxidized products of phosphatidylcholine that can form complexes with polypeptides, including apolipoprotein B. When the monoclonal antibody was precoated onto microtiter wells prior to carrying out a sandwich ELISA using an anti-human apolipoprotein B antibody, it was possible to detect 0.5 ng protein of copper-induced OxLDL. The detection of OxLDL was dependent on the presence of monoclonal antibody and was blocked by oxidized phosphatidylcholine (OxPC). Under the same sandwich ELISA condition, native LDL showed a dose-dependent increase of absorbance that was inhibited by complex of OxPC with BSA. These results suggest the possible occurrence of oxidative modification of human plasma LDL, which is recognized by the antibody against OxPC. The level of LDL oxidation of normal human subjects was found to be 0.52 +/- 0.35 units per 5 mu g protein of LDL, where one unit was defined as the reactivity corresponding to 1 ng of copper-induced OxLDL by this assay. Furthermore, we found that the LDL oxidation level in patients who had been receiving hemodialysis treatment was increased more than eightfold over that of normal subjects. We suggest that LDL in human plasma is oxidatively modified under certain conditions and this method for measurement of OxLDL could be used to study the relationship between in vivo oxidation reaction and various pathological conditions.

Antibodies, Monoclonal↗
PubMed1996

A statistical study of the American Urological Association symptom index for benign prostatic hyperplasia in participants of mass screening program for prostatic diseases using transrectal sonography.

PURPOSE: A study was done on the prevalence of urinary symptoms in community based populations in Japan regarding the influences of aging and benign prostatic hyperplasia (BPH) as evaluated by transrectal sonography. MATERIALS AND METHODS: In 961 Japanese men 55 to 87 years old who underwent mass screening for prostatic diseases the American Urological Association symptom index scores were compared with age and ultrasonic diagnosis of the prostate. RESULTS: Moderate to severe symptoms (symptom score 8 or more) were found in 265 of our 961 samples (27.6%), while BPH was also recognized ultrasonically in 197 (20.5%). Frequencies of urinary symptoms and BPH increased significantly with age. BPH related increase in total symptom scores occurred only in select men when adjusted by age. CONCLUSIONS: The ability of the American Urological Association symptom index to characterize BPH in an individual was limited because of the lack of specificity to the disease along with the considerable influence of aging on the symptom score. Currently, transrectal sonography is the most reliable method for the definitive diagnosis of BPH.

Age Distribution↗
PubMed1996

[Double-dose Gd-DTPA: detectability of intraparenchymal brain metastasis].

PURPOSE: The aim of this study was to assess the efficacy of double-dose (0.2 mmol/kg cumulative dose) gadopentetate dimeglumine (Gd-DTPA) in patients with intraparenchymal brain metastasis. MATERIALS AND METHODS: We studied 119 patients using an incremental-dose technique. After precontrast T1- and T2-weighted spin-echo studies were performed, each patient received an initial injection of 0.1 mmol/kg body weight and an additional dose of 0.1 mmol/kg 6-8 minutes later. RESULTS: Fifty-five cases (65 examinations) showed abnormal findings suggestive of intraparenchymal metastatic brain tumor and were included in the efficacy analysis. More enhancing lesions were detected with double-doses than with a single dose in 39 of 65 examinations (60%). With a single dose of Gd-DTPA. 562 definite and 111 equivocal lesions were found in brain parenchyma, and with an additional dose. 923 definite and 145 equivocal lesions were detected. In three cases, intraparenchymal metastatic brain tumors were detected only with double doses, and in five cases the lesion was solitary with a single dose but multiple after double doses. Based on our results. MR imaging with double doses had a statistical advantages over 0.1 mmol/kg examination in detecting early and/or small metastases. There is no statistical difference between at 0.5T and 1.0-1.5T in improving detectability of metastatic brain tumors after a double dose. We have not experienced any adverse effects of Gd-DTPA in this patient series. CONCLUSION: In surveying brain metastatsis, contrast-enhanced MR imaging with double doses is more useful in detecting lesions than with a single dose of Gd-DTPA.

Adult↗
PubMed1996

[Evaluation of thin section CT scanning in the prone position of metastatic axillary lymph nodes for breast cancer].

A retrospective study was performed to determine whether thin section CT scanning in the prone position of the breast and the axilla yielded useful information regarding the status of axillary lymph nodes in patients with breast cancer. Thirty-six patients with breast carcinomas were scanned preoperatively from the supraclavicular regions to the breast in the prone position with 5 mm sections. Axillary lymph nodes measuring > or = 5 mm on the short axis were considered abnormal. Correlation with axillary dissection was obtained in all patients, giving a positive predictive value for axillary metastases of 83.3%, with 88.2% sensitivity, 84.2% specificity, and 88.8% negative predictive value. We concluded that thin section CT scan in the prone position was an accurate predictor of axillary lymph node involvement. We made a phantom with lymph node swelling to evaluate whether CT scanning with 5 mm sections was necessary for detecting 5 mm swollen lymph nodes. We scanned the phantom with 5 mm and 10 mm sections. Twelve radiologists counted the swollen lymph nodes on 5 mm section images and 10 mm section images of the phantom. The average number of miscounts was 1.1 (miscount rate 6.8%) on 5 mm section and 2.8 (15%) on 10 mm sections. We concluded that 5 mm section CT scanning is superior for detecting 5 mm lymph nodes.

Adult↗
PubMed1996

HLA matching.

1. HLA matching exerts a profound influence on graft outcome. The difference in 3-year graft survival rates between best and worst matched cases was 17% for first grafts and 18% for retransplants. This HLA matching effect persists despite recent improvements in graft outcome. The matching effect at 3-years was 12% for transplants since 1991. 2. Surprisingly, HLA matching is especially important for recipients over age 60. The increase in the HLA matching effect to 20% in patients older than 60 can be attributed to the additive effects of HLA matching on both functional and patient survival. Consequently, graft survival for zero-MM recipients is similar for patients older and younger than age 60. 3. The difference in 3-year survival between zero and 0-MM kidneys was 10% for White and 15% for Black recipients. 4. Transplants with zero-broad but split A,B mismatches had graft outcomes similar to one-A,B,DR MM kidneys. Split DR MM did not affect the outcome of zero-MM kidneys. 5. HLA-matched transplants can be classified according to the degree of identity between the donor and recipient: 6-antigen match, phenotypic match, and zero-MM. Outcome for zero-MM was lower in transplants before 1990, but the 3 types have similar outcomes in recent transplants. The change in UNOS matching policy in 1995 to include zero-MM kidneys doubled the number of shared kidneys. 6. HLA typing from over 150 centers resulted in an error rate for shipped kidneys of less than 5%. Donor antigens retyped at the recipient center resulted in identical antigens for 70% of cases, a broad DR MM for 2.2%, and an A,B MM in 2.6% of the retyped cases. 7. Although increasing cold ischemia time (CIT) had a deleterious effect on survival of MM kidneys, no effect was seen for zero-MM kidneys. 8. An effect of a possible sex-linked minor histocompatibility antigen was demonstrated with improved outcome for male to male zero-MM cadaveric and parent-to-child transplants. 9. Zero-MM kidneys from pediatric donors and donors older than 60 years of age had poorer outcome than MM kidneys before 1991, but the recent experience shows a matching effect even with these marginal donors.

Adult↗
PubMed1995

Mammalian homologues of Caenorhabditis elegans unc-13 gene define novel family of C2-domain proteins.

The unc-13 gene in Caenorhabditis elegans is essential for normal presynaptic function and encodes a large protein with C1- and C2-domains. In protein kinase C and synaptotagmin, C1- and/or C2-domains are regulatory domains for Ca2+, phospholipids, and diacylglycerol, suggesting a role for unc-13 in regulating neurotransmitter release. To determine if a similar protein is a component of the presynaptic machinery for neurotransmitter release in vertebrates, we studied unc-13 homologues in rat. Molecular cloning revealed that three homologues of unc-13 called Munc13-1, -13-2, and -13-3 are expressed in rat brain. Munc13s are large, brain-specific proteins with divergent N termini but conserved C termini containing C1- and C2-domains. Specific antibodies demonstrated that Munc13-1 is a peripheral membrane protein that is enriched in synaptosomes and localized to plasma membranes but absent from synaptic vesicles. Our data suggest that the function of unc-13 in C. elegans is conserved in mammals and that Munc13s act as plasma membrane proteins in nerve terminals. The presence of C1- and C2-domains in these proteins and the phenotype of the C. elegans mutants raise the possibility that Munc13s may have an essential signaling role during neurotransmitter release.

Amino Acid Sequence↗