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Y Mizukami

Publications and source records attributed to Y Mizukami.

At least 55 records · Page 3Linked to original sources
PubMed1998

X-ray contact microscopy system for spectromicroscopy of biological specimens.

An X-ray contact microscopy system has been developed for the study of molecular and elemental distributions in biological specimens based on X-ray absorption characteristics. The system consists of a chamber for measuring XANES (X-ray absorption near-edge structure) of biomolecules, and a contact microscopy system for dried specimens with an electronic zooming tube. With this system the elemental distribution of carbon, nitrogen, oxygen, Ca and Fe in an HeLa cell has been studied, and the DNA-related image using a peak from the XANES profile of the DNA at the K-absorption edge of phosphorus has been obtained.

Journal Article↗
PubMed1998

Abnormal gastric motility in liver cirrhosis: roles of secretin.

Cutaneous electrogastrography (EGG) revealed that the power ratio, an indicator of rhythmicity of EGG waveforms was significantly less in liver cirrhosis (power ratio: 28.2+/-14.5%) than in normal subjects (power ratio: 45.6+/-16.2%) (P < 0.01), thus demonstrating dysrhythmic EGG waveforms for liver cirrhosis. Gastric emptying time (T1/2), calculated from the half-life of retained radioisotope (RI) in the region of interest (ROI) in the stomach following the ingestion of RI containing test meal was significantly prolonged in patients with liver cirrhosis compared to the control (liver cirrhosis vs controls 43.2+/-20.3 min vs 24.8+/-9.6 min, P < 0.01). Of the five gastrointestinal hormones-gastrin, secretin, motilin, cholecystokinin (CCK), and glucagon-serum secretin was significantly higher in liver cirrhosis than the control (P < 0.05) and negatively correlated with the power ratio (r = 0.51, P < 0.01). Normal, regular EGG waveforms (power ratio: 47.1+/-10.2%) became dysrhythmic in normal volunteers (power ratio: 34.1+/-12.4%), when their serum secretin was experimentally increased to essentially that in liver cirrhosis and possible roles of hypersecretinemia in abnormal gastric motility in liver cirrhosis are proposed.

Aged↗
PubMed1998

Association between anomalous pancreaticobiliary ductal union and adenomyomatosis of the gall-bladder.

A frequent association of biliary tract carcinoma and anomalous pancreaticobiliary ductal union (APBD) is well recognized, especially gall-bladder carcinoma in undilated type APBD. However, little is known about the presence and incidence of adenomyomatosis (AMT) of the gall-bladder, a presumed premalignant lesion, in patients with APBD. This retrospective study was conducted to elucidate the clinical features and incidence of AMT in APBD patients with relation to undilated type and dilated type APBD. We reviewed the clinicopathological records of 30 patients with APBD (28 women and two men) encountered during the past 10 years. Among them, 22 patients underwent cholecystectomy and the resected specimens were subjected to histopathological examinations. Eleven cases of APBD patients were undilated type and 11 cases were dilated type. Adenomyomatosis was found in six (55%) of 11 undilated type and one (9%) of 11 dilated type, and fundal type was predominantly observed in six (86%) of seven AMT. An overall incidence of AMT in APBD patients was 32%. An undilated type of APBD is frequently associated with AMT and we believe, therefore, that clinicians should be aware of a possible coexistence of APBD and AMT.

Adenomyoma↗
PubMed1998

Ischemic preconditioning translocates PKC-delta and -epsilon, which mediate functional protection in isolated rat heart.

Protein kinase C (PKC) plays an important role in mediating ischemic preconditioning (PC). However, the relationship between PKC isoforms and PC is still uncertain. We analyzed subcellular localization of PKC isoforms by Western blot analysis in isolated rat heart and demonstrate that PKC-alpha, -delta, and -epsilon were translocated to the membrane fraction associated with the improvement of cardiac function. Translocation of PKC-delta and -epsilon persisted after a 30-min period following PC, but the translocation of PKC-alpha was transient. Under low Ca2+ perfusion (0.2 mmol/l), PC improved the cardiac function associated with the translocation of PKC-delta. Chelerythrine (1.0 micromol/l) suppressed the translocation of all PKC isoforms associated with the loss of improvement of the cardiac function. On the other hand, bisindolylmaleimide (0.1 micromol/l) did not inhibit the improvement of cardiac function induced by PC, which was associated with the translocation of PKC-epsilon. These results indicate that the effect of PC on cardiac function is mediated by the translocation of either PKC-delta or -epsilon independently in rat hearts.

Alkaloids↗
PubMed1998

[Pulmonary metastasis from renal cell carcinoma diagnosed by using thoracoscopic biopsy: a case report].

A 70-year-old woman underwent radical nephrectomy for right renal cell carcinoma and received prophylactic interferon-alpha (rHuIFN-alpha) administration for one year. Followup computerized tomography scan showed a small nodule in the right lung 39 months postoperatively. Pulmonary nodules had become multiple and increased in size (6 mm) at 53 months. To examine the pulmonary lesions, histopathologically thoracoscopic biopsy of the right pulmonary nodule was performed and the diagnosis of metastatic renal cell carcinoma was confirmed. Because of its minimal invasiveness, thoracoscopic biopsy may be indicated in selected cases.

Aged↗
PubMed1997

A novel mechanism of JNK1 activation. Nuclear translocation and activation of JNK1 during ischemia and reperfusion.

Cytokines and various cellular stresses are known to activate c-Jun NH2-terminal kinase (JNK), which plays a role in conveying signals from the cytosol to the nucleus. Here we investigate the translocation and activation of JNK1 during ischemia and reperfusion in perfused rat heart. Ischemia induces the translocation of JNK1 from the cytosol fraction to the nuclear fraction in a time-dependent manner. Immunohistochemical observation also shows that JNK1 staining in the nucleus is enhanced after ischemia. During reperfusion after ischemia, further nuclear translocation of JNK1 is apparently inhibited. In contrast, JNK1 activity in the nuclear fraction does not increased during ischemia but increases significantly during reperfusion with a peak at 10 min of reperfusion. The activation of JNK1 is confirmed by the phosphorylation of endogenous c-Jun (Ser-73) with similar kinetics. The level of c-jun mRNA also increases during reperfusion but not during ischemia. Based on fractionation and immunohistochemical analyses, an upstream kinase for JNK1, SAPK/ERK kinase 1 (SEK1), is constantly present in both the nucleus and cytoplasm throughout ischemia and reperfusion, whereas an upstream kinase for mitogen-activated protein kinase, MAPK/ERK kinase 1, remains in the cytosol. Furthermore, phosphorylation at Thr-223 of SEK1, necessary for its activation, rapidly increases in the nuclear fraction during postischemic reperfusion. These findings demonstrate that JNK1 translocates to the nucleus during ischemia without activation and is then activated during reperfusion, probably by SEK1 in the nucleus.

Animals↗
PubMed1997

Mitogen-activated protein kinase translocates to the nucleus during ischaemia and is activated during reperfusion.

Growth factors and various cellular stresses are known to activate mitogen-activated protein (MAP) kinase, which plays a role in conveying signals from the cytosol to the nucleus. The phosphorylation of MAP kinase is thought to be a prerequisite for translocation. Here, we investigate the translocation and activation of MAP kinase during ischaemia and reperfusion in perfused rat heart. Ischaemia (0-40 min) induces the translocation of MAP kinase from the cytosol fraction to the nuclear fraction. Immunohistochemical observation shows that MAP kinase staining in the nucleus is enhanced after ischaemia for 40 min. Unexpectedly, tyrosine phosphorylation of MAP kinase is unchanged in the nuclear fraction during ischaemia, indicating that unphosphorylated MAP kinase translocates from the cytosol to the nucleus. During reperfusion (0-30 min), after ischaemia for 20 min, tyrosine phosphorylation of MAP kinase in the nuclear fraction is increased with a peak at 10 min of reperfusion. The activation is confirmed by MAP kinase activity with similar kinetics to the tyrosine phosphorylation. However, the amount of MAP kinase in the fraction is almost constant during reperfusion for 10 min. Although an upstream kinase for MAP kinase, MAP kinase/extracellular signal-regulated kinase kinase (MEK)-1, remains in the cytosol throughout ischaemia and reperfusion, MEK-2, another upstream kinase for MAP kinase, is constantly present in the nucleus as well as in the cytoplasm, based on analyses by fractionation and immunohistochemistry. Furthermore, MEK-2 activity in the nuclear fraction is rapidly increased during post-ischaemic reperfusion. These findings demonstrate that nuclear MAP kinase is activated by tyrosine phosphorylation during reperfusion, probably by MEK-2.

Animals↗
PubMed1997

Nuclear translocation of PKC zeta during ischemia and its inhibition by wortmannin, an inhibitor of phosphatidylinositol 3-kinase.

Protein kinase C zeta (PKC zeta), a member of the atypical PKC subgroup, is insensitive to Ca2+, diacylglycerol, and phorbol esters, but is activated by phospholipids such as phosphatidylinositol-3,4,5-triphosphate, a product of phosphatidylinositol 3-kinase (PI3-kinase). Here we show that PKC zeta translocates from the cytosol to the 1000 x g pellet (nuclear-myofibrillar) fraction during ischemia for 40 min in Langendorff-perfused rat hearts. In addition, immunohistochemical observation shows that ischemia induces the translocation of PKC zeta to the nucleus. The nuclear translocation during ischemia is inhibited in a dose-dependent manner by wortmannin (10(-9)-10(-7) M), an inhibitor of PI3-kinase.

Androstadienes↗
PubMed1997

Hepatic infarction with portal thrombosis.

A case of hepatic infarction with portal thrombosis is reported. A 63-year-old woman with liver cirrhosis and esophageal varices was admitted for treatment of the esophageal varices. Endoscopic variceal ligation (EVL) and endoscopic injection sclerotherapy (EIS) were performed. Two months later, she experienced right hypochondralgia and right flank pain. Serum transaminase levels were suddenly elevated, and computed tomography scans of the liver showed multiple small nodular lesions. Her condition worsened, and she died of hepatic failure. Autopsy revealed splenic and portal vein thrombosis, multiple hepatic infarction, and evidence of chronic pancreatitis. We believe that liver cirrhosis and chronic pancreatitis were the main risk factors for the portal thrombosis, and the treatment for esophageal varices appeared to have triggered the thrombosis. The hepatic infarction was caused by the portal thrombosis.

Endoscopy, Digestive System↗
PubMed1997

Thickened inner hypoechoic layer of the gallbladder wall in the diagnosis of anomalous pancreaticobiliary ductal union with endosonography.

BACKGROUND: An anomalous pancreaticobiliary ductal union (APBD) is a high-risk factor for biliary tract carcinoma, which often is not diagnosed before overt malignancy. The early detection of APBD is therefore clinically important. We evaluated the gallbladder wall in APBD patients with endoscopic ultrasonography. METHODS: Clinicopathologic features and ultrasonographic findings of the gallbladder in 33 consecutive patients with APBD between 1986 and 1995 were studied in relation to two subtypes of APBD, that is, undilated (n = 17) and dilated (n = 16). The gallbladder wall was evaluated with conventional ultrasonography and/or endoscopic ultrasonography. Histologic examinations of 25 resected gallbladders were made. RESULTS: Fourteen of the seventeen patients with undilated type APBD (82%) had diffuse thickened gallbladder wall of 4 mm or more, whereas 5 of the 16 with dilated type (31%) had this finding (p < 0.01). The thickened gallbladder wall consisted sonographically of two layers: diffuse thickened inner hypoechoic layer and outer hyperechoic layer. Mucosal hyperplasia was histologically found in 8 of 9 cases (89%) with thickened inner hypoechoic layer on endoscopic ultrasonography. Mucosal hyperplasia was observed in 10 of 11 undilated type APBD cases (91%) in which cholecystectomy was performed. In addition, the presence of anomalous union was shown by endoscopic ultrasonography in 9 of 11 patients with undilated type APBD (82%) and all 7 of those with dilated type. The characteristic ultrasonographic pattern of diffuse thickened inner hypoechoic layer was observed exclusively in patients with mucosal hyperplasia of the gallbladder associated with APBD among 2085 endoscopic ultrasonography examinations performed during the study period. CONCLUSIONS: Diffuse thickened inner hypoechoic layer of the gallbladder wall was frequently observed in APBD patients, especially those with the undilated type, on ultrasonography and/or endoscopic ultrasonography. This finding corresponded histologically to mucosal hyperplasia of the gallbladder mucosa. Thickened inner hypoechoic layer is a useful ultrasonographic sign that indicates mucosal hyperplasia of the gallbladder and, particularly, the possible coexistence of undilated type APBD before the appearance of overt malignancy.

Adult↗
PubMed1997

Implication of protein kinase C-alpha, delta, and epsilon isoforms in ischemic preconditioning in perfused rat hearts.

Ischemic preconditioning is a phenomenon in which one or several cycle(s) of brief ischemia-reperfusion protects the myocardium against the cell injury caused by subsequent prolonged ischemia. Protein kinase C (PKC) inhibitors blunt the cardioprotection arising from ischemic preconditioning. To investigate which PKC isoform is involved in ischemic preconditioning, we identified the PKC isoform that translocates to the membrane fraction by means of immunoblotting with specific antibodies. PKC-alpha, delta, epsilon isoforms all increased in the membrane fraction after three cycles of 3 min ischemia and 5 min reperfusion (ischemic preconditioning) in the perfused rat heart. The ischemic preconditioning significantly improved the recovery of left ventricular developed pressure (LVDP) during reperfusion following 20 min of ischemia. A PKC specific inhibitor, chelerythrine (1.0 microM) blocked the effect of ischemic preconditioning on LVDP recovery and the translocation of PKC-alpha, delta, epsilon isoforms. These data suggest that one or more of these three isoforms of PKC is involved in ischemic preconditioning by phosphorylating membrane proteins.

Animals↗
PubMed1997

Determination of Arabidopsis floral meristem identity by AGAMOUS.

Determinate growth of floral meristems in Arabidopsis requires the function of the floral regulatory gene AGAMOUS (AG). Expression of AG mRNA in the central region of floral meristems relies on the partially overlapping functions of the LEAFY (LFY) and APETALA1 (AP1) genes, which promote initial floral meristem identity. Here, we provide evidence that AG function is required for the final definition of floral meristem identity and that constitutive AG function can promote, independent of LFY and AP1 functions, the determinate floral state in the center of reproductive meristems. Loss-of-function analysis showed that the indeterminate central region of the ag mutant floral meristem undergoes conversion to an inflorescence meristem when long-day-dependent flowering stimulus is removed. Furthermore, gain-of-function analysis demonstrated that ectopic AG function results in precocious flowering and the formation of terminal flowers at apices of both the primary inflorescence and axillary branches of transgenic Arabidopsis plants in which AG expression is under the control of the 35S promoter from cauliflower mosaic virus. Similar phenotypes were also observed in lfy ap1 double mutants carrying a 35S-AG transgene. Together, these results indicate that AG is a principal developmental switch that controls the transition of meristem activity from indeterminate to determinate.

AGAMOUS Protein, Arabidopsis↗
PubMed1997

Thyroid tumor as initial presentation of Hodgkin's disease: a case report including an immunophenotypic characterization.

A rare case of Hodgkin's disease which initially presented with a thyroid tumor in an 18-year-old-man is reported. The tumor involved most of the thyroid gland but was well demarcated, and the border between the tumor and the remnants of the thyroid gland was relatively clear, suggesting secondary Hodgkin's disease involving the thyroid gland. Histologic examination of the tumor revealed nodular sclerosing Hodgkin's disease composed of many peculiar osteoclast--like giant cells and a few typical Reed--Sternberg cells in the background of dominant eosinophils. With an immunophenotypic study it was shown that these giant cells were positive for the monoclonal antibodies LeuM1 and BerH2, but negative for LCA. Thus the histological diagnosis was clearly confirmed.

Adolescent↗
PubMed1997

Retinoblastoma protein and proliferating-cell nuclear antigen expression as predictors of recurrence in well-differentiated papillary thyroid carcinoma.

PURPOSE: We analyzed retinoblastoma protein (pRB) and proliferating-cell nuclear antigen (PCNA) expression in primary tumors and recurrent lesions of well-differentiated papillary thyroid carcinoma (PTC) to clarify the relationship between their expression and recurrent disease. PATIENTS AND METHODS: The study included 93 patients with PTC. No recurrent disease had developed in 60 patients within 10 years after surgery (group N). Thirty patients in whom recurrent disease had developed after surgery were enrolled in group R. Levels of pRB and PCNA expression were quantified using the CAS 200 system (Cell Analysis Systems, Elmhurst, IL) following immunohistochemical staining. RESULTS: Mean pRB expression level in the primary tumors in group R was significantly lower than that in group N (P < .0001). pRB expression in the tumors with a diameter up to 20 mm was significantly lower than that in tumors larger than 20 mm in group R (P < .01). There were no significant differences in the levels of expression of PCNA in the primary tumors between group N and group R. Univariate analysis demonstrated that the disease-free survival was significantly correlated with pN category, pRB, and PCNA expression level. The subgroup with high-level expression of pRB (> 25%) showed significantly long disease-free survival (P < .001). Furthermore, the subgroup with low-level expression of PCNA (< 35%) showed significantly longer disease-free survival (P < .05). Multivariate analysis showed pRB expression and pN category to be independent prognostic factors for disease-free survival in PTC. CONCLUSION: pRB expression level can be used as a reliable predictor for recurrence of PTC.

Carcinoma, Papillary↗
PubMed1996

Translocation of protein kinase C-alpha, delta and epsilon isoforms in ischemic rat heart.

To explore the spatial and temporal localization of PKC isoforms during ischemia, we quantified PKC isoforms in the subcellular fractions in perfused rat heart by immunoblotting using specific antibodies against PKC isoforms. PKCs-alpha and epsilon translocated from the 100000 x g supernatant (S, cytosolic) fraction to the 1000 x g pellet (PI, nucleus-myofibril) and the 1000-100000 x g pellet (P2, membrane) fractions during 5-40 min of ischemia. PKC-delta redistributed from the P2 to the S fraction. A 50-kDa fragment of PKC-alpha appeared during ischemia possibly through calpain action. Immunohistochemical observations showed the different localizations of PKC-alpha, delta, and epsilon in the myocytes. The PKC assay displayed high basal levels of Ca(2+)-independent PKC, the activation of Ca(2+)-dependent PKC in the P1 and P2 fractions, and the activation of Ca(2+)-independent PKC in the P1 fraction after 20 min of ischemia. These observations show that ischemia induces different patterns of translocation of the three PKC isoforms, suggesting differences in their roles.

Animals↗