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Biomedical subjects

M Takamura

Publications and source records attributed to M Takamura.

At least 37 records · Page 2Linked to original sources
PubMed2000

Superparamagnetic iron oxide-enhanced magnetic resonance images of hepatocellular carcinoma: correlation with histological grading.

Superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging has been used for the detection of hepatic tumors. However, little is known about this technique in relation to hepatocellular carcinoma (HCC). The aim of this study was to investigate whether SPIO-enhanced MR imaging can be useful in assessing histological grades of HCC. The authors studied histologically proven tumors including 31 HCCs and 6 dysplastic nodules. The ratio of the Kupffer-cell count in the tumorous tissue relative to that in the nontumorous tissue (Kupffer-cell-count ratio) decreased as HCCs became less well differentiated. The ratio of the intensity of the tumorous lesion to that of the nontumorous area on SPIO-enhanced MR images (SPIO intensity ratio) correlated inversely with Kupffer-cell-count ratio in HCCs and dysplastic nodules (r = -.826, P <.001) and increased as the degree of differentiation of HCCs decreased, indicating that the uptake of SPIO in HCCs decreased as the degree of differentiation of HCCs declined. All of the dysplastic nodules and some well-differentiated HCCs showed hypointense or isointense enhancement, relative to the surrounding liver parenchyma, indicating greater or similar uptake of SPIO in the tumor when compared with nontumorous areas. These results suggest that SPIO-enhanced MR imaging reflects Kupffer-cell numbers in HCCs and dysplastic nodules, and is useful for estimation of histological grading in HCCs, although uncertainties persist in differentiating dysplastic nodules from well-differentiated HCCs.

Aged↗
PubMed2000

Influence of dual ET(A)/ET(B)-receptor blockade on coronary responses to treadmill exercise in dogs.

We hypothesized that endothelin (ET) release during exercise may be triggered by alpha-adrenergic-receptor activation and thereby influence coronary hemodynamics and O(2) metabolism in dogs. Exercise resulted in coronary blood flow increases (to 1.88+/-0.26 from 1.10+/- 0.12 ml x min(-1) x g(-1)) and in a fall (P<0.01) in coronary sinus O(2) saturation (17.4+/-1.5 to 9.6+/-0.7 vol%), whereas myocardial O(2) consumption (MVO(2)) increased (109+/-13% from 145+/-16 microl O(2) min(-1) x g(-1)). Tezosentan, a dual ET(A)/ET(B)-receptor blocker, slightly reduced mean arterial pressure (MAP) and increased heart rate throughout exercise. The relationship between coronary sinus O(2) saturation and MVO(2) was shifted upward (P<0.05) after tezosentan administration; i.e., as MVO(2) increased during exercise, coronary sinus O(2) saturation was disproportionately higher after ET-receptor blockade. After propranolol, tezosentan resulted in significant decreases (P<0.05) in left ventricular pressure, the first derivative of left ventricular pressure over time, and MAP during exercise. As MVO(2) increased during exercise, coronary sinus O(2) saturation levels after tezosentan became superimposable over those observed before ET-receptor blockade. Thus dual blockade of ET(A)/ET(B) receptors alters coronary hemodynamics and O(2) metabolism during exercise, but ET activity failed to increase beyond baseline levels.

Adrenergic beta-Antagonists↗
PubMed2000

A catalytic asymmetric strecker-type reaction promoted by Lewis acid-Lewis base bifunctional catalyst.

A general asymmetric Strecker-type reaction is reported, catalyzed by the Lewis acid-Lewis base bifunctional catalyst 1. The reaction of trimethylsilyl cyanide (TMSCN) with various fluorenyl imines, including n-aldimines and alpha,beta-unsaturated imines, proceeds with good to excellent enantioselectivities in the presence of a catalytic amount of phenol as additive (20 mol%) (catalytic system 1). The products were successfully converted to the corresponding amino acid derivatives in high yields without loss of enantiomeric purity. Furthermore, hydrogenation or dihydroxylation of the products from alpha,beta-unsaturated imines afforded saturated or functionalized aminonitriles also without loss of enantiomeric purity. The absolute configuration of the products and a control experiment using catalyst 2 supported the proposed dual activation of the imine and TMSCN by the Lewis acid (Al) and the Lewis base moiety (phosphine oxide) of 1. From the mechanistic studies including kinetic and NMR experiments of the catalytic species, the role of PhOH seems to be a proton source to protonate the anionic nitrogen of the intermediate. Specifically, we have found that TMSCN is more reactive than HCN in this catalytic system, probably due to the activation ability of the phosphine oxide moiety of 1 toward TMSCN. This fact prompted us to develop the novel catalytic system 2, consisting of 1 (9 mol%), TMSCN (20 mol%) and HCN (1.2 mol eq). This new system afforded comparable results with obtained by system 1 (1 (9 mol%)-TMSCN (2 mol eq)-PhOH (20 mol%)).

Acids↗
PubMed2000

Single breath-hold T2-weighted MR imaging of the liver: value of single-shot fast spin-echo and multishot spin-echo echoplanar imaging.

OBJECTIVE: The objective of our study was to evaluate the efficacy of single breath-hold T2-weighted MR imaging for detection of focal hepatic lesions. MATERIALS AND METHODS: T2-weighted MR images were retrospectively reviewed from 51 patients with 85 solid and 59 nonsolid lesions using the following four sequences: conventional spin-echo, respiratory-triggered fast spin-echo, single-shot fast spin-echo, and multishot spin-echo echoplanar imaging. Images were reviewed on a hepatic segment-by-segment basis; T2-weighted images of a total of 408 hepatic segments were reviewed separately and independently for solid and nonsolid lesions by four radiologists. Quantitative, qualitative, and receiver operating characteristic analyses were performed. RESULTS: For solid lesions, no significant differences were seen among the lesion-to-liver contrast-to-noise ratios with the four sequences. In terms of solid lesion detection, no significant difference was seen between the diagnostic accuracy of multishot spin-echo echoplanar (Az = 0.90) and respiratory-triggered fast spin-echo (Az = 0.91) imaging, which showed the best performance of the four sequences. For nonsolid lesion detection, respiratory-triggered fast spin-echo and single-shot fast spin-echo imaging were judged the best (Az = 0.94). CONCLUSION: Breath-hold single-shot fast spin-echo and multishot spin-echo echoplanar sequences can be substituted for conventional spin-echo and respiratory-triggered fast spin-echo T2-weighted sequences.

Adult↗
PubMed2000

[Transcatheter arterial embolization for advanced hepatocellular carcinoma--indications and limitations].

Many patients with advanced hepatocellular carcinoma (HCC) in stage IV have no surgical indications. Transcatheter methods such as transcatheter arterial embolization (TAE) and hepatic arterial infusion chemotherapy play a main role of the treatment for advanced HCC. Conventional TAE (from proper hepatic artery) is performed for patients without liver dysfunction. Patients with severe liver dysfunction could not in the past be treated with TAE, but lately it has become possible to treat them with the method of segmental TAE or subsegmental TAE due to the development of a microcatheter and advances in equipment. Although technical progress is remarkable, there are no fixed guidelines for advanced HCC. Suitable methods for individuals need to be discussed.

Antibiotics, Antineoplastic↗
PubMed1999

Two-dimensional guided M-mode color tissue Doppler echocardiography in artificial preexcitation models.

The purpose of this study was to analyze the left ventricular contraction patterns in artificial preexcitation models by using 2-dimensional guided M-mode color tissue Doppler echocardiography. Three types of preexcitation models were produced in 12 patients by right atrio-mitral annular sequential pacing, carried out at the left ventricular lateral, posterior, and posteroseptal walls. Tissue Doppler M-mode was recorded at anteroseptal, posterior, lateral, and posteroseptal sites in the parasternal short-axis view. The time interval from the onset of the QRS complex during sinus rhythm or from the annular pacing spike during fusion beats to the beginning of systolic motion was measured. During sinus rhythm, the time interval at the anteroseptal wall was shortest. During fusion beats, the time intervals at the mitral annular pacing sites were shortest. In preexcitation models, tissue Doppler M-mode could clearly distinguish the difference of left ventricular contraction patterns and detect the earliest contraction site of the left ventricle.

Cardiac Pacing, Artificial↗
PubMed1999

Comparative significance of p53 and WAF/1-p21 expression on the efficacy of adjuvant chemotherapy for resectable invasive ductal carcinoma of the pancreas.

p53 tumor-suppressor gene has a dual role as a trigger of apoptosis and as an initiator of DNA repair. The cyclin-dependent kinase inhibitor WAF/1-p21 is induced by wild-type p53 and has been implicated as a downstream mediator of the growth-suppressing and apoptosis-promoting function of wild-type p53, suggesting an impact on the effectiveness of chemotherapy. This study was designed to assess the significance of p53 and WAF/1-p21 expression in the prognosis of patients and the efficacy of adjuvant chemotherapy for resectable invasive ductal carcinoma (IDC) of the pancreas. A total of 58 patients with primary IDC of the pancreas underwent pancreatectomy between 1982 and 1996: 28 patients underwent surgery alone, and 30 patients received postsurgical adjuvant chemotherapy. p53 and WAF/1-p21 were stained immunohistochemically with anti-p53 monoclonal antibody (mAb) and anti-WAF/1-p21 mAb. p53 was positively expressed in 29 (50%) of 58 primary lesions, and p21 was expressed in 24 (41%) lesions; however, p21 expression did not necessarily correlate with p53 expression. The survival curve of the patients with p53(+) IDC was significantly lower than that of those with p53(-) IDC, and p21(+) patients showed a higher survival curve than did p21(-) patients, but this difference was not statistically significant. When p53 and p21 expression were analyzed in combination, the patients with p53(+)p21(-) IDC were found to have a significantly poorer prognosis than others. On the other hand, the survival curve of the adjuvant chemotherapy group was also higher than that of the surgery-alone group, but this difference was not significant. In a multivariate analysis, p21 expression was a significantly low risk factor for death due to IDC overall, and adjuvant chemotherapy was found to decrease the risk of death from IDC in p53(+) patients. Evaluation of expression of p53 and WAF/1-p21 may be beneficial in the prediction of the patient's prognosis as well as prediction of the effects of adjuvant chemotherapy in pancreatic cancer patients.

Adult↗
PubMed1999

Detection of the earliest ventricular contraction site in patients with Wolff-Parkinson-White syndrome using two-dimensional guided M-mode tissue Doppler echocardiography.

OBJECTIVE: The purpose of this study was to examine the feasibility of M-mode tissue Doppler imaging for localizing the accessory pathway in patients with Wolff-Parkinson-White (WPW) syndrome. METHODS: Two-dimensional guided tissue Doppler M-mode was recorded at the mitral and tricuspid annular levels in 13 WPW patients. Time intervals were measured from the onset of the delta wave or the R wave to the beginning of the ventricular systolic motion. The earliest contraction site was defined as the site demonstrating the shortest time interval, and compared with the earliest activated site determined by body surface mapping and the successful ablation site. RESULTS: In 6 patients with a left-sided pathway, tissue Doppler localization was identical to the ablation site. In 3 with a left-sided pathway and 3 with a right-sided pathway, localization was judged as an adjacent region of the ablation site. In 1 patient with a right lateral pathway, the pathway location was misdiagnosed. The tissue Doppler diagnosis for the left-sided pathways correlated well with the ablation site, in contrast to the right-sided pathways (p = 0.05). Prediction of the accessory pathway localization by tissue Doppler M-mode was equivalent to localization based on body surface mapping. CONCLUSIONS: In WPW syndrome, tissue Doppler M-mode can detect the earliest contraction sites and seems helpful in localizing the left-sided accessory pathways, but is of limited use for right-sided pathways.

Adolescent↗
PubMed1999

Percutaneous microwave hepatic tumor coagulation with segmental hepatic blood flow occlusion in seven patients.

OBJECTIVE: We assess the usefulness of microwave hepatic tumor coagulation therapy with balloon occlusion of segmental hepatic blood flow for eight recurrent metastatic hepatic tumors in seven patients. CONCLUSION: Limited early experience with microwave hepatic tumor coagulation therapy and segmental hepatic blood flow occlusion has been positive, suggesting that further clinical evaluation is warranted.

Catheterization↗
PubMed1998

A Case of Multiple Juvenile Papillomatosis of the Breast and Its Immunohistochemical Pathology.

Juvenile papillomatosis(JP)is a benign proliferative disease of the breast affecting young women. Some patients with JP develop breast carcinoma. We recentlytreated and followed a case of JP in a 16-year-old female, and studied its immunohistochemical characteristics. The patient noticed a small tumor, 5 mm in diameter, in the periareolar region on the medial side of the right breast. She underwent an excisional biopsy and pathology demonstrated JP. However, 6 months later, two new lesions were discovered by routine echogram examination, and were later excised. Immunohistochemistry demonstrated that the JP tumors were negative for estrogen receptor, but positive for progesterone receptor, epidermal growth factor receptor and erbB-2. In addition, tests for p53 were negative and Rb protein was normally expressed. Immunohistochemical analysis suggested that an abnormality in estrogen receptor is important in the pathogenesis of JP, and that the patient had a relatively high risk of developing breast carcinoma, since her JP is multicentric and recurrent. The present study also suggests that immunohistochemical pathology may be beneficial in assessing the malignant potential of JP.

Journal Article↗
PubMed1998

Bilateral coronary artery fistulas with multiple sites of drainage.

A 49-year-old woman presented with bilateral coronary fistulas with multiple sites of drainage. She had been referred to hospital for evaluation of a cardiac murmur, and a coronary arteriogram revealed multiple coronary fistulas. One fistula originated from the proximal part of the left anterior descending coronary artery and connected to the main pulmonary artery. Three coronary artery fistulas arised from a conal branch of the right coronary artery and drained into the main pulmonary artery, the right atrium and the great cardiac vein. This is the first reported case of bilateral coronary fistulas with multiple sites of drainage.

Coronary Angiography↗
PubMed1997

DNA binding properties of the hfq gene product of Escherichia coli.

We found that plasmids isolated by alkaline-lysis method occasionally showed abnormal mobility on agarose gel electrophoresis. This abnormality was not detected after phenol extraction of plasmids, indicating that it was caused by proteinous factor(s). A 15-kDa protein was found in the plasmid preparations on SDS-PAGE. The sequence of eighteen N-terminal amino acid residues of the 15-kDa protein was identical with the host factor I (HF-I) encoded by the hfq gene at 95 min on the Escherichia coli chromosome map, which is known to be required for bacteriophage Qbeta replication. The HF-I protein was purified and in vitro DNA binding experiment was carried out. HF-I bound to both supercoiled DNA and linear DNA and the binding of HF-I seemed to be sequence-nonspecific.

Amino Acid Sequence↗
PubMed1997

Intracranial intraparenchymal schwannoma: report of three cases.

Intracranial intraparenchymal schwannomas are rare. We report three patients with an intracranial intraparenchymal schwannoma and discuss the clinical and neuroradiological aspects of this particular tumour. The patients were a 21-year-old male, a 64-year-old female and a 17-year-old male. The tumours were located in cerebrum in two patients and the cerebellum in one patient. Computerized tomography (CT) scans demonstrated a slightly high density area with homogeneous enhancement by contrast medium. Magnetic resonance imaging (MRI) showed slightly low signal intensity on the T1-weighted image, high or mixed signal intensity on the T2-weighted image and homogeneous enhancement by gadolinium diethylene triamine penta-acetic acid (Gd-DTPA). Radiological studies revealed cystic components in 2 of the 3 patients. All tumours were firm, well-demarcated, and completely removed. The diagnosis of schwannoma was derived from histological and immunohistochemical studies in all 3 cases; 2 cases were also examined by electron microscopy.

Adolescent↗
PubMed1997

A quinolinone derivative, vesnarinone (OPC-8212), significantly inhibits the in vitro and in vivo growth of human pancreatic cancer cell lines.

A quinolinone derivative, vesnarinone, has been used as a cardiotonic agent. Previous studies have demonstrated that vesnarinone has potent antitumor activity. The present study was designed to assess the antitumor effects of vesnarinone on human pancreatic cancer cell lines in vitro and in vivo. The in vitro effects of vesnarinone on the human pancreatic cancer cell lines (PANC-1, MIA PaCa-2 and BxPC-3) were assessed by the MTT assay, the Trypan blue dye exclusion test and the Matrigel invasion chamber assay. The inhibition of in vivo tumor growth was evaluated on two human pancreatic cancer xenografts (BxPC-3 and SPa-1) transplanted s.c. into nude mice. The dose of vesnarinone for 50% inhibition of cell growth in a 7 day culture ranged between 10 and 20 micrograms/ml as verified by the Trypan blue dye exclusion test. The dose for 50% cytotoxicity after a 3 day culture in the MTT assay was 32 micrograms/ml for PANC-1 and 30 micrograms/ml for BxPC-3, but 50% cytotoxicity for MIA PaCa-2 was not achieved by the maximal dose of vesnarinone (50 micrograms/ml). Nomalsky optic microscopy and acridine orange staining demonstrated the vacuolization and crater-like changes in the cell nucleus after vesnarinone treatment. Moreover, staining of an apoptosis marker (Le(y) protein) and nick end-labeling increased. Vesnarinone also inhibited cancer invasion in the Matrigel invasion chamber assay. In vivo, BxPC-3 and SPa-1 were s.c. transplanted into the nude mice, and vesnarinone (5 or 50 mg/kg) was daily administered orally for 21 days. In both lines, vesnarinone at 50 mg/kg achieved significant inhibition. The present study suggests that vesnarinone may be a new therapeutic agent for pancreatic cancer.

Adenocarcinoma↗
PubMed1996

c-fos gene expression in postnatal rat retinas with light/dark cycle.

We examined the diurnal variation of c-fos gene expression during a 12:12 light/dark cycle in developing rat retinas by in situ hybridization histochemistry. c-fos Gene was not expressed before postnatal day 10 (P10) but was expressed on P15 in the outer nuclear layer throughout the dark period and in the inner nuclear layer and the ganglion cell layer during the light period. These results demonstrated that the earliest c-fos gene expression occurred between P11 and P15. The good correlation between the expression of c-fos gene and the genes coding for proteins involved in phototransduction, in terms of their diurnal variation and in their development, suggested that c-fos gene may play a role in the regulation of these genes in retinal cells during the light/dark cycle.

Animals↗