Biomedical subjects

Takashi Sakamoto

Publications and source records attributed to Takashi Sakamoto.

At least 19 recordsLinked to original sources

PubMed2007

Methimazole-induced cell death in rat olfactory receptor neurons occurs via apoptosis triggered through mitochondrial cytochrome c-mediated caspase-3 activation pathway.

The administration of methimazole is known to induce cell death in rat olfactory receptor neurons (ORNs). We investigated whether this injury occurs via apoptosis or through necrosis and whether it involves the extrinsic or intrinsic pathway. Rats were intraperitoneally injected with vehicle (control) or 300 mg/kg methimazole. The experimental animals were also administered vehicle or a caspase-3 or caspase-9 inhibitor 30 min earlier. The administration of methimazole induced cell death predominantly in the mature ORNs and partially reduced olfactory sensitivity in the rats; the injured cells were TUNEL-positive and showed a nuclear staining pattern. This insult induced cytochrome c release from the mitochondria and a significant increase in the immunoreactivity of activated caspase-3 and caspase-9 as well as that of cleaved poly-ADP-ribose-polymerase; in addition, it caused a significant increase in the fluorogenic activity of caspase-3 and caspase-9. However, it did not affect the immunoreactivity of activated caspase-8 or the fluorogenic activity of caspase-8. Pretreatment with a caspase-3 or caspase-9 inhibitor nearly completely prevented the morphologic, biochemical, and functional changes induced by methimazole. These findings suggest strongly that methimazole-induced cell death in rat ORNs is predominantly apoptosis; moreover, the majority of this apoptotic cell death is triggered through mitochondrial cytochrome c-mediated caspase-3 activation pathway, and both caspase-3 and caspase-9 inhibitors can prevent methimazole-induced cell death in the ORNs.

Animals↗

PubMed2006

Helper virus-independent trans-replication of hepatitis C virus-derived minigenome.

We have previously described a synthetic T7-driven cDNA minigenome containing the antisense sequence of luciferase gene and internal ribosome entry site of encephalomyocarditis virus flanked by 5'- and 3'-end sequences of hepatitis C virus (HCV) that contain cis-acting replication elements. Synthesis of minus-strand RNA from the artificial minigenome was determined by using Huh-7 cells harboring autonomously replicating HCV subgenome as a helper for provision of functional replication components. To further confirm and extend these studies, we investigated here whether the minigenome replication system could be reconstituted by transfection of naïve Huh-7 cells with plasmid expressing nonstructural (NS) proteins. Reporter assay and Northern blot analysis revealed that trans-expression of NS proteins from 3 to 5 resulted in high level of luciferase activity and synthesized minus-strand RNA. The analogous result was also obtained with the minigenome derived from HCV 2a, and both HCV 1b- and 2a-derived NS protein were able to support the chimeric minigenomes whose 5'- or 3'-end was replaced by the respective region of the heterologous virus. These results provide a basis for establishing the reverse genetic system that is helpful to study cis- and trans-acting factors involved in HCV RNA replication.

Cell Line, Tumor↗

PubMed2006

Aluminum inhibits proteolytic degradation of amyloid beta peptide by cathepsin D: a potential link between aluminum accumulation and neuritic plaque deposition.

Neuritic plaques are the key pathological feature of Alzheimer's disease, and amyloid beta (Abeta) peptides are major component of these plaques. In this study, we demonstrated the influence of aluminum (Al) on the Abeta peptide degradation by cathepsin D. Al did not directly affect the cathepsin D activity using small synthetic substrate. However, when Abeta peptides were used as substrate, the apparent inhibitory effect of Al on cathepsin D activity was observed. This inhibitory effect disappeared by treatment of desferrioxamine. These results indicate that Al has the potential to interact and disrupt Abeta peptide catabolism via the inhibition of proteolytic degradation.

Aluminum↗

PubMed2006

In vitro evaluation of metallic coronary artery stents with sub-millimeter multi-slice computed tomography using an ECG-gated cardiac phantom: relationship between in-stent visualization and stent type.

The aim of this experimental study was to investigate visualization of various coronary artery stents with sub-millimeter multi-slice spiral computed tomography (MSCT) using a cardiac physical phantom. Four 3-mm stents of various designs were implanted in tubes with an inner diameter of 3 mm to simulate coronary artery. Stents were placed on a cardiac phantom and scanned at different heart rates. Retrospective ECG-gated adaptive segmental reconstruction technique was employed. Profile curves across longitudinal curved planar reconstruction images of the stents were generated. From the profile curve, the full width at half maximum was defined as the stent lumen index. The effect of heart rate and stent type on the stent lumen index was evaluated. Visual evaluation for each stent at various heart rates was also performed. The heart rate had no significant effect on in-stent visualization. However, in-stent visualization differed significantly for the various stent types for both profile curve analysis and visual evaluation (the Tukey-Kramer multiple comparisons test). Multiple regression analysis indicated that strut thickness, especially minimal strut thickness, was the significant influencing factor for the in-stent visualization. On the basis of four stent models examined it would appear that visualization of the coronary stent lumen varies depending on the stent type, but not on the heart rate. Stents with slim struts are preferable for in-stent evaluation with multi-slice spiral computed tomography.

Biocompatible Materials↗

PubMed2006

Usefulness of paroxetine in depressed men with paroxysmal atrial fibrillation.

The occurrence and the duration of paroxysmal atrial fibrillation (AF) are influenced by vagal tone. Paroxetine, an antidepressant, can modulate vagal tone at the level of the mid-brain and inhibit the vasovagal reflex. In this study, oral paroxetine 10 mg/day was administered to patients with multidrug-resistant paroxysmal AF. Nine consecutive men responded favorably to the drug. In 3 patients, AF resolved completely. One patient could not tolerate the drug because of nausea and nervousness. These preliminary results suggest that paroxetine could be a choice in the pharmacologic treatment of paroxysmal AF.

Adult↗

PubMed2006

Real-time monitoring of antibody secretion from hybridomas on a microchip by time-resolved luminescence anisotropy analysis.

This article presents a real-time monitoring system for cellular analysis using micro total analysis systems technology. Time-resolved luminescence anisotropy analysis was adopted for real-time detection of small amounts of a target protein produced by a small number of cells. The system was tested by real-time monitoring of the antibody secretion by hybridomas. The cells were successfully cultivated in a micro-incubation chamber (240 nl) fabricated on a microchip. The quantification of the antibody was achieved using the Ru(II) complex-labeled Staphylococcus aureus protein A probe, which can bind specifically to the Fc region of the antibody. Using this system, we detected as little as 24 fmol of immunoglobulin G under physiological conditions without the bound/free separation protocol. We successfully achieved real-time and quantitative monitoring of small amounts of antibody production by approximately 200 hybridoma cells. This method could be applied to various cellular analyses using small numbers of cells.

Animals↗

PubMed2006

Characterization of muscarinic receptor-mediated cationic currents in longitudinal smooth muscle cells of mouse small intestine.

In mouse intestinal smooth muscle cells held at -50 mV, carbachol evoked an atropine-sensitive inward current in the intracellular presence of Cs(+). The current response consisted of an initial peak followed by a smaller plateau component on which oscillatory currents frequently arose. Results from various experimental procedures indicated that the inward current is a muscarinic receptor-operated cationic current (mI(cat)) sensitive to cytosolic Ca(2+) concentration ([Ca(2+)](i)) and that the initial peak and oscillatory components are contaminated by Ca(2+)-activated Cl(-) currents. Under conditions of [Ca(2+)](i) buffered to 100 nM, the mI(cat) response to cumulative carbachol applications was inhibited competitively by an M(2)-selective antagonist but non-competitively by an M(3)-selective one. Also it was severely reduced by pertussis toxin (PTX) treatment or a phospholipase C (PLC) inhibitor. Comparative analysis of mI(cat) in mouse and guinea-pig intestinal myocytes indicated that the underlying channels resemble between those myocytes in agonist sensitivity, current-voltage relationship, and unitary conductance. The results suggest that in mouse intestinal myocytes, mI(cat) arises mainly via an M(2)/M(3) synergistic mechanism involving PTX-sensitive G-proteins and PLC activity in the absence of current modulation by [Ca(2+)](i) changes, as described for guinea-pig ileal mI(cat). The channels underlying mI(cat) are also indistinguishable in gating properties between both types of myocytes.

Animals↗

PubMed2006

A linkage map for brown trout (Salmo trutta): chromosome homeologies and comparative genome organization with other salmonid fish.

We report on the construction of a linkage map for brown trout (Salmo trutta) and its comparison with those of other tetraploid-derivative fish in the family Salmonidae, including Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), and Arctic char (Salvelinus alpinus). Overall, we identified 37 linkage groups (2n = 80) from the analysis of 288 microsatellite polymorphisms, 13 allozyme markers, and phenotypic sex in four backcross families. Additionally, we used gene-centromere analysis to approximate the position of the centromere for 20 linkage groups and thus relate linkage arrangements to the physical morphology of chromosomes. Sex-specific maps derived from multiple parents were estimated to cover 346.4 and 912.5 cM of the male and female genomes, respectively. As previously observed in other salmonids, recombination rates showed large sex differences (average female-to-male ratio was 6.4), with male crossovers generally localized toward the distal end of linkage groups. Putative homeologous regions inherited from the salmonid tetraploid ancestor were identified for 10 pairs of linkage groups, including five chromosomes showing evidence of residual tetrasomy (pseudolinkage). Map alignments with orthologous regions in Atlantic salmon, rainbow trout, and Arctic char also revealed extensive conservation of syntenic blocks across species, which was generally consistent with chromosome divergence through Robertsonian translocations.

Animals↗

PubMed2006

Solid-phase detection of RNA using bispyrene-modified RNA probe.

Bispyrene modified 2'-O-methyl oligoRNA (OMUpy2), which is a useful fluorescent probe for specific RNA detection, was immobilized on a glass substrate via various linker molecules to develop a more convenient RNA detection chip for gene expression study. As the fluorescence intensity of OMUpy2 enhanced greatly when it hybridized with its complementary RNA, it was expected that RNA detection by OMUpy2-immobilized chip (RNA-chip) required neither fluorescent labels to target nucleic acid nor washing protocol after the hybridization. As the linker molecules, oligo(dT), agarose, and poly(ethylene glycol) (PEG) were chosen, and the fluorescence from the chip was measured by a fluorescence microscope. Results indicated that the RNA-chip was able to detect the complementary oligoribonucleotide (cORN) without target labeling and washing protocols. Furthermore, the background emission was reduced as the length of the linker increased. In the case of PEG linker, 25-fold enhancement of the fluorescence intensity of the OMUpy2 was observed upon the addition of cORN.

Fluorescent Dyes↗

PubMed2006

Properties of novel antisense oligonucleotides containing 2'-O-modified adenosine with a photo-reactive group.

In order to enhance the efficiency of antisense molecules for target RNA regulation, a novel photo-reactive antisense oligonucleotide was developed. We designed and synthesized a photo-reactive antisense oligonucleotide containing an adenosine in which 2'-OH was modified with 4,5',8-trimethylpsoralen (Ps) via an ethoxymethylene linkage (2'-Ps-eom). We evaluated the photo-cross-linking efficiency and sequence specificity toward complementary RNA (match-RNA). 2'-Ps-eom was selectively photo-cross-linked to the match-RNA. The photo-cross-linking efficiency was about 75% upon UVA-irradiation (365 nm) for 10 min. Previously, we reported oligonucleotides that had an adenosine anchoring Ps at 2'-O-position via a methylene linkage (2'-Ps-met). The photo-cross-linking efficiency of 2'-Ps-met and match-RNA was about 35% upon UVA-irradiation for 120 min. The photo-cross-linking efficiency of 2'-Ps-eom was dramatically enhanced in comparison with the one of 2'-Ps-met.

Adenosine↗

PubMed2006

Identification and characterization of a novel human collectin CL-K1.

Collectins are a family of C-type lectins with two characteristic structures, collagen like domains and carbohydrate recognition domains. They recognize carbohydrate antigens on microorganisms and act as host-defense. Here we report the cloning and characterization of a novel collectin CL-K1. RT-PCR analyses showed CL-K1 mRNA is present in all organs. The deduced amino acid sequence and the data from immunostaining of CL-K1 cDNA expressing CHO cells revealed that CL-K1 is expressed as a secreted protein. CL-K1 is found in blood by immunoblotting and partial amino acid analyses. CL-K1 showed Ca(2+)-dependent sugar binding activity of fucose and weakly mannose but not N-acetyl-galactosamine, N-acetyl-glucosamine, or maltose, though mannose-binding lectin (MBL) containing similar amino acid motif. CL-K1 can recognize specially several bacterial saccharides due to specific sugar-binding character. Elucidation of the role of two ancestor collectins of CL-K1 and CL-L1 could lead to see the biological function of collectin family.

Amino Acid Sequence↗

PubMed2006

Influence of radiation dose rate and lung dose on interstitial pneumonitis after fractionated total body irradiation: acute parotitis may predict interstitial pneumonitis.

This study evaluated patients for the influence of the dose rate and lung dose of fractionated total body irradiation (TBI) in preparation for allogeneic bone marrow transplantation (BMT) on the subsequent development of interstitial pneumonitis (IP). Sixty-six patients at our institute were treated with TBI followed by BMT. All of the patients received a total TBI dose of 12 Gy given in 6 fractions over 3 days and were divided into 3 groups according to the radiation dose rate and lung dose: group A, lung dose of 8 Gy (n = 18); group B, lung dose of 12 Gy at 8 cGy/min (n = 25); and group C, lung dose of 12 Gy at 19 cGy/min (n = 23). The overall survival rate, the cumulative incidence of relapse, and the cumulative incidence of IP were evaluated in relation to various potential indicators of future IP. There were no significant differences in survival and relapse rates between patient group A and combined groups B and C. Clinically significant IP occurred in 13 patients. The cumulative incidence of IP was significantly higher in patients who developed acute parotitis as indicated by either an elevation in the serum amylase level or parotid pain of grade 1 to 2. There was no difference in IP incidence among groups A, B, and C. There was no significant difference in IP incidence between lung dose values of 8 Gy (with lung shielding) and 12 Gy (without lung shielding) and between dose rate values of 8 cGy/min and 19 cGy/ min, at least when TBI was given in 6 fractions. The presence of acute parotitis during or just after TBI may be a predictor of IP.

Adolescent↗

PubMed2006

Leukemic and meningeal relapse of CD5+ intravascular large B-cell lymphoma with down-modulation of CD20 after rituximab therapy.

Although CD20- relapses of B-cell lymphoma following rituximab therapy have increasingly been reported recently, coexistence of both the original and selected clones on relapse in a single patient have not been described. We experienced such a case with rare CD5+ intravascular lymphomatosis (IVL). A 46-year-old woman was admitted because of IVL complicated with cauda equina syndrome and pulmonary infarction. Complete remission was successfully achieved with multidrug chemotherapy in combination with rituximab. However, the disease recurred after 8 months with leukemic progression and meningeal involvement. The phenotype of the abnormal lymphocytes in the peripheral blood was fundamentally the same (CD20+CD5+CD10-CD19+CD23-sIglambda+) as that of the cells in the cerebrospinal fluid (CSF). However, CD20 expression was decreased remarkably compared with that in the CSF and that in the bone marrow before therapy. The targeting of CD20 molecules on the tumor cell surface by rituximab may have provided a selective pressure on lymphoma cells. The escape phenomenon of the lymphoma cells from rituximab was observed by simultaneously comparing the CD20 expression of cells in the peripheral blood and in a site of sanctuary from rituximab, the CSF.

Antibodies, Monoclonal↗

PubMed2006

16-MDCT aortography with a low-dose contrast material protocol.

OBJECTIVE: The objective of our study was to evaluate whether a low-dose contrast material (CM) protocol with a saline flush might provide sufficient contrast enhancement in aortoiliac 16-MDCT angiography. SUBJECTS AND METHODS: Forty-five patients were divided into two groups on the basis of the CM (300 mg I/mL) administration protocol: group 1 (23 patients) received 100 mL of CM at 3.0 mL/sec; and group 2 (22 patients), 50 mL of CM at 3.0 mL/sec followed by a 20-mL saline flush at 3.0 mL/sec. All patients underwent 16-MDCT angiography of the entire aortoiliac region. Seven regions of interest (ROIs) were drawn from the ascending aorta (ROI 1) to the external iliac artery (ROI 7). Quantitative analysis was performed by calculating the mean aortoiliac attenuation and the mean difference between the maximum and minimum attenuation values. Vascular enhancement of the renal arteries was visually assessed using 2D and 3D postprocessing techniques. RESULTS: The mean aortoiliac attenuation in group 1 was 314.3 +/- 45.9 H and that in group 2 was 306.1 +/- 35.0 H. The difference was not statistically significant. Adequate mean aortoiliac attenuation was achieved in 95.7% (22/23) and 95.5% (21/22) of patients in groups 1 and 2, respectively. The difference was not statistically significant. The mean difference between the maximum and minimum attenuation values was significantly smaller in group 1 (41.3 +/- 16.8 H) than in group 2 (57.2 +/- 25.3 H). The renal arteries were assessable in all patients in both groups. CONCLUSION: This protocol of 50 mL of CM with a saline flush provides attenuation comparable to that obtained with the 100 mL of CM in aortoiliac 16-MDCT angiography.

Aged↗

PubMed2006

Cardiac 16-MDCT for anatomic and functional analysis: assessment of a biphasic contrast injection protocol.

OBJECTIVE: The purpose of this study was to determine the optimal contrast injection protocol for clear delineation of the endocardial and epicardial contours and coronary vessels in anatomic and functional imaging with cardiac 16-MDCT. SUBJECTS AND METHODS: Thirty-eight patients were allocated to three groups according to contrast injection protocol: a long-duration biphasic protocol in which diluted contrast material was used in the latter phase (protocol A, 13 patients); a uniphasic protocol with saline flush (protocol B, 12 patients); a uniphasic protocol without a flush (protocol C, 13 patients). Six regions of interest were drawn within the left ventricle (LV), right ventricle (RV), and interventricular septum along the z-axis. Mean ventricular attenuation, mean difference between maximum and minimum ventricular attenuation, and ventricular-myocardial contrast-to-noise ratio (CNR) were calculated. Attenuation and visualization of the coronary vessels also were compared. RESULTS: The difference between maximum and minimum RV attenuation was significantly smaller in group A (58.1 H) than in groups B (179.5 H) and C (157.0 H). RV-myocardial CNR was significantly higher in group A (9.0) than in group B (5.5). The mean LV attenuation, difference between maximum and minimum LV attenuation, and LV-myocardial CNR were not significantly different among three groups. In protocol A, both endocardial and epicardial contours were clearly delineated, and cardiac functional analysis was feasible in all cases. Average attenuation and visualization of the coronary vessels were not significantly different among groups. The diagnostic accuracies in detection of coronary stenosis were 92%, 93%, and 91%, respectively, for protocols A, B, and C. CONCLUSION: The long-duration contrast injection protocol with diluted contrast material is optimal for assessing the coronary vessels and cardiac function.

Aged↗

PubMed2006

A case of metachronous bilateral breast cancer with bilateral radiation pneumonitis after breast-conserving therapy.

We report a patient with metachronous bilateral breast cancer who has twice developed radiation pneumonitis after breast-conserving therapy for each breast. The patient was a 48-year-old woman, who presented with Stage I right breast cancer. After wide excision of the right breast tumor and dissection of level I axillary lymph nodes, systemic therapy with oral 5-FU and tamoxifen was started. Subsequently, tangential irradiation with a total dose of 50 Gy in 25 fractions was given. Seven months after irradiation, she developed respiratory symptoms and radiation pneumonitis was diagnosed. The symptoms resolved with oral prednisolone. Thirty months after the right breast cancer treatment, Stage I left breast cancer was diagnosed. After wide excision of the left breast tumor and partial removal of the level I axillary lymph nodes, the same oral systemic chemo-hormonal therapy was initiated. Thereafter, tangential irradiation with a total dose of 50 Gy in 25 fractions was given. Four months after irradiation, she developed respiratory symptoms. A chest X-ray showed an area of increased density in the left lung consistent with radiation pneumonitis. The symptoms were mild and they improved spontaneously without medication. Although there is insufficient evidence to justify or withhold whole breast radiation therapy from patients with a history of contralateral breast cancer and radiation pneumonitis, it is essential to discuss the adequacy of whole breast irradiation and the possibility of alternative approaches, such as breast-conserving surgery without irradiation or partial breast irradiation for this rare condition.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2006

[Clinical inspection of metastasis to the mesenteric lymph nodes in patients with hypopharyngeal cancer after pharyngolaryngectomy with free jejunal graft-136 cases].

Single-stage reconstruction of the pharyngoesophagus with a free jejunal graft is considered standard surgical treatment for hypopharyngeal cancer. We reviewed postoperative cervical CTs in 72 of 136 consecutive patients (1982-2002) undergoing this therapy in our department. Of these, 29 (40%) showed mesenteric lymph node swelling (> 10mm) in grafts. Most swelling is considered reactive, but 1 patient showed pathological metastasis in fine-needle aspiration cytology (FNA). When metastasis is clinically suspected in imaging study and other examinations, FNA should be done carefully with guided ultrasound echo-imaging, to avoid damaging vascular grafts and necrosis of the jejunal graft.

Aged↗

PubMed2005

Chemoradiotherapy in patients with pancreatic carcinoma: phase-I study with a fixed radiation dose and escalating doses of weekly gemcitabine.

AIM: The aim of this phase-I study is to determine the maximum tolerated dose (MTD) of weekly gemcitabine in concurrent combination with a total radiation dose of 54 Gy in patients with pancreatic cancer. METHODS: In all patients, a total dose of 54 Gy was delivered in 30 fractions of 1.8 Gy/day. Gross tumor volume and regional lymph nodes were included in the irradiated volume with a 1- to 1.5-cm margin. The doses of weekly gemcitabine were escalated from 100 mg/m2 by increments of 50 mg/m2. Dose-limiting toxicity (DLT) was defined as hematologic toxicity, prolonged grade-3 non-hematologic toxicity, and incompletion of the planned treatment. RESULTS: Twenty-six patients entered the trial. From level 1 (100 mg/m2) to level 4 (250 mg/m2), no patient experienced DLT except for 1 patient at level 1. At level 5 (300 mg/m2), 3 of the 5 patients met the DLT criteria. One patient developed severe pulmonary abscess, and the other 2 patients had hematologic DLT. The overall partial response rate was 29%, and the median survival time was 13.7 months. The first relapse occurred at the in-field primary site in 6 patients and at distant organs in 13 patients. CONCLUSION: The MTD of weekly gemcitabine was 250 mg/m2 in the present chemoradiotherapy setting. The efficacy of this chemoradiotherapy regimen is currently being evaluated in the phase-II setting.

Adult↗