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H Imamura

Publications and source records attributed to H Imamura.

At least 19 recordsLinked to original sources
PubMed1999

High level expression of Thermococcus litoralis 4-alpha-glucanotransferase in a soluble form in Escherichia coli with a novel expression system involving minor arginine tRNAs and GroELS.

The Thermococcus litoralis 4-alpha-glucanotransferase (GTase) gene has a high content of AGA and AGG codons for arginine, which are extremely rare in Escherichia coli. Expression of the GTase gene in E. coli resulted in low protein production and the accumulation of inclusion bodies. However, simultaneous expression of GTase with tRNA(AGA), tRNA(AGG) and GroELS affected both the production and solubility of GTase, and production of soluble GTase increasing about 5-fold. This new E. coli expression system should be applicable to the expression of not only archaeal but also eukaryotic genes, which usually contain a large number of AGA and AGG codons.

Chaperonin 60↗
PubMed1999

Preoperative portal vein embolization: an audit of 84 patients.

Preoperative portal vein embolization (PVE) was performed in 84 patients before extensive liver resection for various diseases. By the criteria of liver volumetric determination, some patients were candidates for PVE, whereas others were not, even though the same surgical procedure, such as extended right lobectomy (ERL), was scheduled. PVE using gelatin sponge powder induced hypertrophy in the nonembolized lobe (0%-171%; median, 30%) and proportional atrophy in the embolized lobe in 2 weeks without eliciting any major inflammatory or necrotic reaction, as evidenced histologically and by the minimal elevations in the serum aspartate transaminase (AST) and alanine transaminase (ALT) values. Alterations in the total bilirubin level and prothrombin time were also insignificant and transient, indicating that hepatocyte functions were not impaired by PVE. Not all patients who undergo PVE proceed with the scheduled hepatic resection procedure, so it is a great advantage that gelatin sponge causes minimal damage compared with other embolizing materials such as cyanoacrylate and absolute ethanol, which have been reported to induce an inflammatory reaction or histological alteration. Our multiple regression analysis showed that three factors, diabetes mellitus, a high total bilirubin level at the time of PVE, and being male, each reduced the extent of hypertrophy in the nonembolized lobe (r2 =.30). By contrast, cholestasis appeared to accelerate the process of atrophy in the embolized lobe (r2 =.16). In conclusion, PVE by gelatin sponge powder is a safe and effective preoperative maneuver that induces hypertrophy of the section of the liver that will remain after partial hepatectomy.

Adult↗
PubMed1999

A role of protein kinase C in the regulation of cytosolic phospholipase A(2) in bradykinin-induced PGI(2) synthesis by human vascular endothelial cells.

The purpose of this study was to elucidate the mechanism by which bradykinin (BK) enhances prostacyclin (PGI(2)) production in human umbilical vein endothelial cells (HUVEC). BK-induced enhancement of PGI(2) synthesis was observed in a dose- and time-dependent manner, and it also increased [Ca(2+)](i) followed by enhancement of cytosolic phospholipase A(2) (cPLA(2)) activity. The PKC inhibitors GF109203X and H7 attenuated the BK-induced increase in [Ca(2+)](i) and inhibited the BK-induced PGI(2) synthesis. Phorbol 12-myristate 13-acetate increased cPLA(2) activity and PGI(2) synthesis but failed to alter [Ca(2+)](i). BK increased cPLA(2) mRNA eightfold by 15 min, and this increase was inhibited by pretreatment with the PKC inhibitors. In response to cycloheximide pretreatment, cPLA(2) mRNA was superinduced. These results suggest that BK stimulates PGI(2) synthesis in HUVEC by activation of cPLA(2) by dual mechanisms: an elevation of [Ca(2+)](i) and a PKC-dependent pathway. Moreover, changes in calcium kinetics and expression of cPLA(2) mRNA may underlie the BK-induced PGI(2) enhancement in these cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1999

Surgical treatment for a supra sinotubular junctional saccular aneurysm associated with aortic regurgitation.

We reported a patient with a saccular ascending aortic aneurysm located just above the non-coronary sinotubular junction. The aneurysm produced severe aortic regurgitation and two episodes of cardiac tamponade. By intraoperative inspection, the border between the aneurysmal wall and non-dilated portion of the normal aortic wall was distinct, and the aortic valve leaflets and aortic annulus appeared normal. Aortic valve dysfunction appeared to be caused by dilation of the noncoronary sinotubular junction and mild distortion of the noncoronary sinus because of the aneurysmal formation. We performed patch closure of the aneurysmal ostium and repaired the dilated noncoronary sinotubular junction. Postoperative echocardiography and aortography demonstrated a good coaptation of the aortic valve leaflets with trivial aortic regurgitation. Although a rupture site, dissection or carcinomatous pericarditis which is attributable to the two episodes of cardiac tamponade could not be found, pathologic examination of the aneurysm wall revealed intramural blood leakage between the mucoid degenerated media and notably thickened adventitia. In addition, there was thinning and interruption of the elastic fibers of the media. These findings are consistent with a leaking aneurysm which cause the slow development of cardiac tamponade.

Aortic Aneurysm↗
PubMed1999

Treatment strategy for multiple hepatic metastases of colorectal carcinoma.

We describe the treatment strategy for multiple hepatic metastases of colorectal carcinoma based on a review of the literature and our own results. Although a number of studies have suggested that multiplicity or bilobar distribution of metastases is associated with poor outcome, liver resection is thought to be the only potentially curative treatment. The only contraindications to surgery are the presence of extrahepatic metastases (with the exception of resectable lung metastases) and if radical removal of all detectable tumors is not possible. Hepatectomy should be performed with the aim of maintaining a delicate balance between radical removal of tumors and the preservation of as much residual hepatic mass as possible with minimal blood loss. Surgeons should be familiar with the use of intraoperative ultrasonography, a standard adjunct to liver resection. Preoperative portal vein embolization may be indicated in selected patients as a means of inducing hypertrophy in the remaining hepatic parenchyma.

Adenocarcinoma↗
PubMed1999

Effect of probucol on intracellular pH and proliferation of human vascular endothelial cells.

We investigated the effect of probucol on the intracellular pH ([pH]i) and proliferation of human umbilical vein endothelial cells (HUVEC), as well as their production of prostacyclin (PGI2). The addition of probucol produced a biphasic shift in [pH]i, with a brief initial acidification followed by a rapid alkaline shift. After pretreatment with EGTA, the initial decrease in [pH]i was abolished, and the subsequent increase was inhibited. After pretreatment with amiloride, only the increase of [pH]i was abolished. These results suggest that the probucol-induced increase of [pH]i was mainly dependent on Na+/H+ exchange and partly on extracellular Ca2+. In contrast, the addition of LDL produced a decrease of [pH]i. Under Ca2+-free condition, [pH]i was further decreased by LDL. In cells pretreated with amiloride, however, [pH]i was not further decreased by LDL. It was found that probucol promoted cell proliferation, and LDL inhibited cell proliferation. Addition of probucol also enhanced prostacyclin generation by HUVEC. This enhancement of PGI2 generation resulted from increased release of Ca2+ from the storage sites, due not only to increased production of inositol 1,4,5-triphosphate (IP3) but also to the increase of [pH]i. These findings may help to explain the antiatherosclerotic action of probucol.

Amiloride↗
PubMed1999

The expression of variant exon v7-v8 CD44 antigen in relation to lymphatic metastasis of human breast cancer.

The purpose of this prospective study was to evaluate the expression of CD44 splice variant epitopes in human breast cancer and their potential as prognostic indicators. Invasive breast cancer tissues obtained from 91 patients were examined for expression of the standard CD44 antigen and variant CD44 antigens (v5, v6, v7, v7-v8, and v8-v10) by immunohistochemical staining to investigate the relations of these antigens to clinicopathological factors and prognosis. The expression of standard CD44 antigen was detected in 54.9% of 91 patients with primary human breast cancer. The variant epitopes of CD44 examined, i.e., v5, v6, v7, v7-v8, and v8-v10, were expressed in 54.9%, 54.9%, 0%, 34.1%, and 0%, respectively. There was a significant difference in tumor size, lymph nodal status, and degree of lymphatic permeation between patients who were positive for exon v7-v8 and those negative for this variant (p < 0.01). Prognosis was also significantly worse in patients positive for CD44 v7-v8 than in those negative for this variant. However, multivariate analysis with the three prognostic indicators tumor size, lymph nodal status, and the degree of lymphatic invasion, has shown that the expression of CD44 v7-v8 antigen in breast carcinoma was not a significant independent prognostic factor and was closely dependent on lymphatic invasion and nodal status. Fourteen of 31 patients who were positive for CD44 v7-v8 experienced recurrences. The mode of recurrence was lymphatic metastasis in 10 out of these 14 patients. Breast cancer cells expressing v7-v8 CD44 antigen have an extremely high affinity for lymph nodes and lymphatic vessels, and are likely to metastasize to distant lymph nodes even at a very early stage in the progression of this disease. This suggests that not only the anatomical factors but also organ affinity plays an important role in the establishment of lymph nodal metastasis of breast cancer.

Adult↗
PubMed1999

Prognostic significance of MIB1-determined proliferative activities in intraductal components and invasive foci associated with invasive ductal breast carcinoma.

The prognostic significance of the proliferative activities in intraductal components and invasive foci was investigated using 157 cases of invasive ductal breast carcinoma in which intraductal components predominated. Proliferative activity was expressed as the number of MIB1-positive nuclei per 1000 cancer cells in the most active areas of intraductal components (MLI-DCIS) or invasive foci (MLI-INV). MLI-DCIS correlated closely with MLI-INV (r = 0.710, 95% confidence interval, 0.623-0.780; P < 0.0001). Both MLI-DCIS and MLI-INV were related to oestrogen receptor (ER) (P = 0.0006, P = 0.0028 respectively), grade of invasive tumour (P < 0.0001, P < 0.0001 respectively) and classification of intraductal components (P < 0.0001, P < 0.0001 respectively). In the univariate disease-free survival analysis, both MLI-DCIS and MLI-INV were found to be significant (P < 0.0001, P = 0.0003 respectively). However, in node-negative cases, only MLI-DCIS was significant (P = 0.0416). Multivariate analysis revealed that MLI-DCIS was significant not only in all cases, but also in node-negative cases (P = 0.0223, P = 0.0426 respectively), whereas MLI-INV was not. These findings indicate that MIB1-determined proliferative activity of intraductal components is a significant prognostic determinant of invasive ductal breast carcinoma in which intraductal components predominate.

Adult↗
PubMed1999

Prognostic significance of anatomical resection and des-gamma-carboxy prothrombin in patients with hepatocellular carcinoma.

BACKGROUND: Portal venous tumour extension and intrahepatic metastasis result in a poor prognosis following hepatectomy for hepatocellular carcinoma (HCC). Anatomical resection is, in theory, preferable for eradicating these types of invasion. Des-gamma-carboxy prothrombin (DCP) has been reported to be associated with adverse pathological variables. This study investigated the significance of anatomical resection and DCP as predictive factors for postoperative recurrence of HCC. METHODS: A retrospective cohort study was carried out in 138 consecutive patients who underwent hepatectomy for HCC smaller than 5 cm using the Cox proportional hazards model. RESULTS: Eight factors were univariately related to poor prognosis (in decreasing order of hazard ratio): intrahepatic metastasis, multiple tumours, alpha-fetoprotein 32 ng/ml or more; DCP greater than 0.1 arbitrary units (AU), tumour-exposed surgical margin, vascular invasion, non-anatomical resection and tumour 2.5 cm or more. Three variables (DCP, vascular invasion and tumour-exposed surgical margin) were excluded by a stepwise procedure in multivariate analysis. Although DCP was not an independent prognostic factor, a model replacing intrahepatic metastasis with DCP showed similar predictive accuracy in a receiver-operating characteristic curve. CONCLUSION: Anatomical resection appeared to have a beneficial effect on recurrence-free survival after hepatectomy for HCC. DCP measurement was effective in predicting HCC recurrence and had the advantage that it can be assessed before operation.

Biomarkers↗
PubMed1999

Interleukin-1alpha stimulated prostacyclin release by increasing gene transcription of prostaglandin H synthase and phospholipase A2 in human vascular endothelial cells.

This study was conducted to evaluate the effects of interleukin-1alpha (IL-1alpha) on prostacyclin (PGI2) production in cultured human vascular endothelial cells in association with intracellular Ca2+, inositol 1,4,5-trisphosphate (IP3), and with prostaglandin H synthase (PGHS) and phospholipase A2 (PLA2) gene expression by using the competitive polymerase chain reaction (PCR) method. IL-1alpha did not increase PGI2 production for 15 min, but induced an increase of about three-fold relative to that in controls at 60 and 180 min. IL- 1alpha had no effect on intracellular Ca2+ levels throughout the experimental period. In this study, consistent with previous reports, PGHS-1 messenger RNA (mRNA) was constitutively expressed, whereas PLA2 mRNA was not. After stimulation with IL-1alpha, PLA2 mRNA level showed an eightfold increase within 15 min, and PGHS-2 mRNA level increased by 76-fold within 180 min. PGHS-1 mRNA level was increased 1.6-fold at 180 min. These results suggest the existence of regulatory mechanisms of IL-1alpha-induced PGI2 production, which involve PGHS and PLA2 gene transcription.

Base Sequence↗
PubMed1999

Oxygen uptake, heart rate, and blood lactate responses during and following karate training.

PURPOSE: The purpose of this study was to examine whether each exercise and an entire karate training session can achieve: 1) accepted training intensity thresholds for effective aerobic capacity training, 2) energy expenditure (EE) thresholds for total body mass and fat weight loss, and 3) elevation in excess postexercise oxygen consumption (EPOC). METHODS: We investigated physiological responses during five types of karate training: basic techniques without (S-Basics) and with (M-Basics) movements, sparring techniques without (TECH I) and with (TECH II) an opponent, and kata. RESULTS: The mean percent of maximal oxygen uptake (%VO2max) and HR (%HRmax) for S-Basics were below the accepted threshold (60% of HRmax or 50% of VO2max) and for M-Basics, TECH I and TECH II were above the threshold for increasing VO2max. For kata and the entire 70 min of karate training, the mean %HRmax were slightly above the threshold, and %VO2max were slightly below the threshold. The mean EPOC measured for 5 min immediately following 70 min of karate training did not differ from the resting VO2. The mean EE resulting from 70 min of karate exercise and EPOC were 2355.4+/-316.3 kJ and 38.8+/-32.7 kJ, respectively. CONCLUSIONS: Although the training intensity of karate exercises studied was moderate and the effects of karate training on EPOC were minimal, the mean value of EE was well above the accepted threshold for total body mass and fat weight loss.

Adult↗
PubMed1999

Carbapenem derivatives as potential inhibitors of various beta-lactamases, including class B metallo-beta-lactamases.

A variety of 1beta-methylcarbapenem derivatives were screened to identify inhibitors of IMP-1 metallo-beta-lactamase, a class B beta-lactamase, in an automated microassay system using nitrocefin as a substrate. The structure-inhibitory-activity relationship study revealed that three types of 1beta-methylcarbapenems having benzothienylthio, dithiocarbamate, or pyrrolidinylthio moieties at the C-2 position showed good inhibitory activity. Among the compounds screened, J-110,441, having a benzothienylthio moiety at the C-2 position of 1beta-methylcarbapenem, was the most potent inhibitor of class B metallo-beta-lactamases with K(i) values of 0. 0037, 0.23, 1.00, and 0.83 microM for IMP-1 encoded by the bla(IMP) gene, CcrA from Bacteroides fragilis, L1 from Stenotrophomonas maltophilia, and type II from Bacillus cereus, respectively. In a further characterization study, J-110,441 also showed inhibitory activity against TEM-type class A serine beta-lactamase and chromosomal class C serine beta-lactamase from Enterobacter cloacae with K(i) values of 2.54 and 0.037 microM, respectively. Combining imipenem or ceftazidime with J-110,441 had a synergistic effect on the antimicrobial activity against beta-lactamase-producing bacteria. Against the isolates of IMP-1-producing Serratia marcescens, the MICs of imipenem decreased to levels ranging from 1/64 to 1/4 in the presence of one-fourth of the MIC of J-110,441. Against E. cloacae producing high levels of class C beta-lactamase, the MIC of ceftazidime decreased from 64 to 4 microg/ml in the presence of 4 microg of J-110,441 per ml. This is the first report to describe a new class of inhibitor of class B and class C beta-lactamases including transferable IMP-1 metallo-beta-lactamases.

Bacterial Proteins↗
PubMed1999

Pseudoaneurysm of the left ventricle progressing from a subepicardial aneurysm.

A 56-year-old man presented with an inferior myocardial infarction and a huge pseudoaneurysm below the inferior surface of the left ventricle, which had progressed from a small subepicardial aneurysm over a 6-month period. Transthoracic echocardiography, Doppler color flow images, radionuclide angiocardiography, magnetic resonance imaging and contrast ventriculography all revealed an abrupt disruption of the myocardium at the neck of the pseudoaneurysm, where the diameter of the orifice was smaller than the aneurysm itself, and abnormal blood flows from the left ventricle to the cavity through the orifice with an expansion of the cavity in systole and from the cavity to the left ventricle with the deflation of the cavity in diastole. Coronary angiography revealed 99% stenosis at the atrioventricular nodal branch of the right coronary artery. At surgery the pericardium was adherent to the aneurysmal wall and a 1.5-cm orifice between the aneurysm and the left ventricle was seen. Pathological examination revealed no myocardial elements in the aneurysmal wall. The orifice was closed and the postoperative course was uneventful. Over-intense physical activity as a construction worker was considered to be the cause of the large pseudoaneurysm developing from the subepicardial aneurysm. These findings indicate that a subepicardial aneurysm may progress to a larger pseudoaneurysm, which has a propensity to rupture, however, it can be surgically repaired.

Aneurysm, False↗
PubMed1999

Proximal bile duct stricture disguised as malignant neoplasm.

BACKGROUND: Discrimination of malignant proximal bile duct (PBD) stricture from a benign lesion is difficult with nonsurgical methods; indeed, 8% to 13% of PBD strictures prove to be benign after histologic examination of the surgically resected specimen. METHODS: In a 7-year period 178 patients with PBD stricture were admitted, and 99 of them underwent radical resection for presumably malignant lesions. In 14 of these patients the stenotic lesions were proved to be benign by postoperative histologic assessment. We reviewed these patients retrospectively by collecting data from their charts. RESULTS: Preoperative radiologic findings including cholangiography and angiography were compatible with malignancy in all 14 patients. Preoperative histologic studies suggested malignancy in 2 of 8 examined. Findings at laparotomy could not allow differentiation between malignant and benign lesions in any of the patients and strongly suggested malignancy in 3. Histologic examination of the resected specimens revealed extensive fibrosis with inflammatory cellular infiltration in all patients. There was 1 episode of significant morbidity postoperatively (transient cholangitis) but no mortality. CONCLUSION: Benign PBD strictures, although rare, are usually indistinguishable from malignant PBD strictures by preoperative or perioperative investigation. Given the minimal morbidity, all PBD strictures should be presumed malignant and managed accordingly, even at the risk of overtreating some benign cases.

Aged↗
PubMed1998

Selectins induced by interleukin-1beta on the human liver endothelial cells act as ligands for sialyl Lewis X-expressing human colon cancer cell metastasis.

We have previously reported that colon cancer cells metastasized to the liver expressed an increased amount of sialyl Lewis X (SLeX) antigen compared to their corresponding primary lesions. It is now well known that SLeX antigen and sialyl Lewis A (SLeA) antigen are ligands for the selectins expressed on the endothelial cells. Therefore, it is assumed that SLeX-rich colon cancer cells could be easily adhered to the endothelial cells that express selectins. In this report we have tried to induce selectin expression on the human liver sinusoidal endothelial cells and have examined the adhesion of SLeX-high or -low expressing colon cancer cells to the interleukin-1beta (IL-1beta)-treated liver specimens using Stamper-Woodruff assay. These human colon cancer cells are termed KM12HX or KM12LX cells, respectively. A significantly increased number of KM12HX cells adhered to the IL-1beta-treated liver specimens compared to KM12LX cells. The adhesion of KM12HX cells was inhibited by the pretreatment of tumor cells with anti-SLeX antibody or by the pretreatment of liver specimens with anti-selectin antibodies. Selectin expression on the liver sinusoidal endothelial cells and endothelial cells of blood vessels after IL-1beta treatment was confirmed by immunohistochemically using anti-selectin monoclonal antibodies (MAbs). These findings strongly suggest that SLeX-expressing cancer cells could adhere to the sinusoidal endothelial cells via an SLeX-selectin interaction system and this could be a first step for colon cancer cells that metastasize to the liver. The mechanism by which these selectins can be induced in vivo is the next problem to be considered.

Cells, Cultured↗
PubMed1998

Interaction of Bnr1p with a novel Src homology 3 domain-containing Hof1p. Implication in cytokinesis in Saccharomyces cerevisiae.

Proteins containing the formin homology (FH) domains FH1 and FH2 are involved in cytokinesis or establishment of cell polarity in a variety of organisms. We have shown that the FH proteins Bni1p and Bnr1p are potential targets of the Rho family small GTP-binding proteins and bind to an actin-binding protein, profilin, at their proline-rich FH1 domains to regulate reorganization of the actin cytoskeleton in the yeast Saccharomyces cerevisiae. We found here that a novel Src homology 3 (SH3) domain-containing protein, encoded by YMR032w, interacted with Bnr1p in a GTP-Rho4p-dependent manner through the FH1 domain of Bnr1p and the SH3 domain of Ymr032wp. Ymr032wp weakly bound to Bni1p. Ymr032wp was homologous to cdc15p, which is involved in cytokinesis in Schizosaccharomyces pombe, and we named this gene HOF1 (homolog of cdc 15). Both Bnr1p and Hof1p were localized at the bud neck, and both the bnr1 and hof1 mutations showed synthetic lethal interactions with the bni1 mutation. The hof1 mutant cells showed phenotypes similar to those of the septin mutants, indicating that HOF1 is involved in cytokinesis. These results indicate that Bnr1p directly interacts with Hof1p as well as with profilin to regulate cytoskeletal functions in S. cerevisiae.

Actins↗