Search PubMed⌕ Search

Biomedical subjects

S Fujiwara

Publications and source records attributed to S Fujiwara.

At least 37 records · Page 2Linked to original sources
PubMed2002

Pulsed Doppler tissue imaging for the assessment of myocardial viability: comparison with 99mTc sestamibi perfusion imaging.

The aim of the present study was to examine whether Doppler tissue imaging demonstrated comparable diagnostic performance for the detection of viable myocardium compared to myocardial perfusion imaging with Tc hexakis-2-methoxyisobutylisonitrile (MIBI). We studied 30 patients with old myocardial infarction who underwent percutaneous transluminal coronary angioplasty (PTCA). Myocardial single photon emission computed tomography (SPECT) with Tc-MIBI and two-dimensional echocardiography were carried out within 7 days before PTCA. We measured regional Tc-MIBI uptake for each myocardial segment from SPECT and peak systolic velocity and a ratio of regional pre-ejection period to regional ejection time (PEP/ET) from pulsed Doppler tissue imaging. Biplane left ventriculography was performed before interventional procedures and repeated 3 months after PTCA. Myocardial viability was determined when wall motion was improved at least one grade after PTCA. The peak systolic velocity was positively correlated with regional Tc-MIBI uptake (R =0.59, P<0.01). The PEP/ET demonstrated inverse correlation with Tc-MIBI uptake ( R=-0.59, P<0.01). Peak systolic velocity of viable segments was higher than that of non-viable segments ( P<0.05). The PEP/ET was lower in viable segments than in non-viable segments ( P<0.05). Peak systolic velocity and PEP/ET demonstrated high diagnostic accuracy for detecting viable myocardium compared with Tc-MIBI perfusion imaging (80% and 79% vs 90%). These data indicate that measurements of regional peak systolic velocity and PEP/ET by Doppler tissue imaging are useful for evaluating myocardial viability quantitatively and provide helpful information for a clinical judgment in an interventional strategy.

Adult↗
PubMed2001

The protective action of nefiracetam against electrophysiological and metabolic damage in the hippocampus after deprivation of glucose and oxygen.

The present study examined the effect of nefiracetam on ischemic brain damage by monitoring population spikes (PSs) in the dentate gyrus of guinea pig hippocampal slices; assaying high-energy phosphates (ATP and CrP) in guinea pig hippocampal slices; and monitoring whole-cell membrane-currents and intracellular Ca(2+) levels in cultured hippocampal neurons. Twenty-minute ischemic insult to slices, i.e., deprivation of glucose and oxygen from artificial cerebrospinal fluid, abolished PSs. As compared with only 35% recovery of the PS amplitude for control, PS amplitude reversed to 65% of basal levels 40 min after returning normal conditions by treatment with nefiracetam (0.01 microM). Ischemic insult reduced the levels of adenosine triphosphate (ATP) and creatine phosphate (CrP) in slices, and when returned to normal conditions, recovering to 70 and 85% of basal values, respectively, 30 min after returning normal conditions. Nefiracetam (0.01 microM) facilitated the recovery of ATP and CrP, reaching 110 and 140% of basal values, respectively. Nefiracetam inhibited N-methyl-D-aspartate (NMDA)-evoked currents to 35% of basal amplitudes. Likewise, nefiracetam (0.01 microM) inhibited intracellular Ca(2+) rise through NMDA receptor channels to 30% of basal levels. The results of the present study, thus, suggest that nefiracetam has the potential to protect against ischemic brain damage, possibly in part by preventing from accumulation of intracellular calcium through NMDA receptor channels.

Adenosine Diphosphate↗
PubMed2001

Denaturation and aggregation of hen egg lysozyme in aqueous ethanol solution studied by dynamic light scattering.

We applied dynamic light scattering technique on the model system of hen egg lysozyme in salt-free aqueous ethanol solution to study the mechanism of denaturation and aggregation of protein. At low ethanol concentration [0-63% (v/v)], the fast relaxation mode was observed, which was caused by lysozyme molecules in the solution interacting with each other with strong repulsive electrostatic force. At 45 and 63% (v/v) ethanol, the slow relaxation mode was also observed, which showed translational diffusive nature, similar to that observed in salt-free polyelectrolyte solution. At 72 or 81% (v/v) ethanol, the slow mode disappeared, leaving only the fast mode. However, the mutual diffusion coefficients obtained from the fast mode at 72 and 81% (v/v) ethanol decreased by about one order of magnitude compared with those from the fast mode at 0-63% (v/v). The reported alcohol-induced conformational transformation of lysozyme molecules at >60% (v/v) ethanol from their native structure to an alpha-helix-rich structure might cause such drastic decrease in the mutual diffusion coefficients. At the highest ethanol concentration of 90% (v/v), the slow mode reappeared, and its relaxation rate was decreasing with elapsed time, which is possibly due to the growth of aggregates of lysozyme molecules. X-ray diffraction results suggested that the intermolecular beta-sheet formation caused the aggregation. Thus, our results indicated that the change in molecular structure of lysozyme closely relates to the diffusion of molecules and their aggregation.

Animals↗
PubMed2001

Inhibition of the binding of enterotoxigenic Escherichia coli Pb176 to human intestinal epithelial cell line HCT-8 by an extracellular protein fraction containing BIF of Bifidobacterium longum SBT2928: suggestive evidence of blocking of the binding receptor gangliotetraosylceramide on the cell surface.

The extracellular protein fraction (P100V) containing the protein BIF produced by Bifidobacterium longum SBT2928 (BL2928), which inhibits the binding of enterotoxigenic Escherichia coli Pb176 (ETEC) to the glycolipid binding receptor gangliotetraosylceramide (GA1) also inhibited the binding of ETEC to the human intestinal epithelial cell line HCT-8 (ATCC CCL 244) in a dose-dependent manner. ETEC-binding inhibitory experiments using crude colonization factor antigen (CFA)-II prepared from ETEC, rabbit anti-GA1 antiserum, medium containing GA1 and media containing lectins, as the binding-inhibitors, suggest that the interaction between the CFA-II antigen present on the cell surface of ETEC and GA1 expressed on HCT-8 cells plays a significant role in the adherence between them. It is strongly suggested that the P100V fraction works as a blocker for the ETEC receptor GA1 on HCT-8 cells.

Bacterial Adhesion↗
PubMed2001

Photoinduced group transfer radical addition of carbamotelluroates to acetylenes.

[reaction: see text] Te-Phenyl carbamotelluroates 1 add to acetylenes under irradiation of visible light to yield beta-telluroacrylamides 2 regioselectively. This reaction would be initiated by homolytic cleavage of the carbamoyl carbon-tellurium bond, producing carbamoyl and PhTe radicals. The addition reaction proceeds via a radical chain mechanism comprising two processes: (i) addition of carbamoyl radicals at the terminal carbon of the triple bond, giving vinylic radicals, and (ii) S(H)2 reaction on the Te atom caused by the attack of the vinyl radicals to 1.

Journal Article↗
PubMed2001

Long and accurate PCR with a mixture of KOD DNA polymerase and its exonuclease deficient mutant enzyme.

DNA polymerase from Thermococcus kodakaraensis KOD1 (previously Pyrococcus sp. KOD1) is one of the most efficient thermostable PCR enzymes exhibiting higher accuracy and elongation velocity than any other commercially available DNA polymerase [M. Takagi et al. (1997) Appl. Environ. Microbiol. 63, 4504-4510]. However, when long distance PCR (>5 kbp) was performed with KOD DNA polymerase, amplification efficiency (product yield) becomes lower because of its strong 3'-5' exonuclease activity for proof-reading. In order to improve a target length limitation in PCR, mutant DNA polymerases with decreased 3'-5' exonuclease activity were designed by substituting amino acid residues in conserved exonuclease motifs, Exo I (Asp141-Xaa-Glu), Exo II (Asn210-Xaa-Xaa-Xaa-Phe-Asp), and Exo III (Tyr311-Xaa-Xaa-Xaa-Asp). Exonuclease activity and amplification fidelity (error rate) of the DNA polymerases were altered by mutagenesis. However, long and accurate PCR by a single-type of mutant DNA polymerase was very difficult. The wild-type DNA polymerase (WT) and its exonuclease deficient mutant (N210D) were mixed in different ratio and their characteristics in PCR were examined. When the mixed enzyme (WT and N210D) was made at the ratio of 1:40, long PCR (15 kbp) at lower mutation frequency could be efficiently achieved.

Amino Acid Sequence↗
PubMed2001

Crystal structure of DNA polymerase from hyperthermophilic archaeon Pyrococcus kodakaraensis KOD1.

The crystal structure of family B DNA polymerase from the hyperthermophilic archaeon Pyrococcus kodakaraensis KOD1 (KOD DNA polymerase) was determined. KOD DNA polymerase exhibits the highest known extension rate, processivity and fidelity. We carried out the structural analysis of KOD DNA polymerase in order to clarify the mechanisms of those enzymatic features. Structural comparison of DNA polymerases from hyperthermophilic archaea highlighted the conformational difference in Thumb domains. The Thumb domain of KOD DNA polymerase shows an "opened" conformation. The fingers subdomain possessed many basic residues at the side of the polymerase active site. The residues are considered to be accessible to the incoming dNTP by electrostatic interaction. A beta-hairpin motif (residues 242-249) extends from the Exonuclease (Exo) domain as seen in the editing complex of the RB69 DNA polymerase from bacteriophage RB69. Many arginine residues are located at the forked-point (the junction of the template-binding and editing clefts) of KOD DNA polymerase, suggesting that the basic environment is suitable for partitioning of the primer and template DNA duplex and for stabilizing the partially melted DNA structure in the high-temperature environments. The stabilization of the melted DNA structure at the forked-point may be correlated with the high PCR performance of KOD DNA polymerase, which is due to low error rate, high elongation rate and processivity.

Amino Acid Sequence↗
PubMed2001

Two kinds of archaeal chaperonin with different temperature dependency from a hyperthermophile.

Thermococcus kodakaraensis KOD1 produces two kinds of chaperonin subunits, CpkA and CpkB. To monitor the expression levels of CpkA and CpkB, anti-CpkA and anti-CpkB antisera were obtained by using synthesized peptides as the haptens. These haptens were prepared based on the carboxyl terminus regions of CpkA and CpkB, which show clear differences in amino acid sequence. Immunoblotting analysis using obtained antisera revealed that the expression levels of CpkA and CpkB changed depending on the cultivation temperature. When cells were grown at 95 degrees C, intracellular amount of CpkA was low, while CpkB was expressed at extremely high level in KOD1. In the case of 70 degrees C cultivation, CpkA existed as the major chaperonin in the cell, whereas CpkB existed as the minor one. Temperature-shift experiments showed that the expression of CpkB was induced by the up-shift and reduced by the down-shift of temperature. In contrast, the expression of CpkA was reduced by the up-shift and induced by the down-shift of temperature. Furthermore, native PAGE and immunoprecipitation experiments revealed that the stoichiometrical ratio of CpkA and CpkB in chaperonin complex changed according to growth temperature.

Antibody Specificity↗
PubMed2001

Epiplakin, a novel member of the Plakin family originally identified as a 450-kDa human epidermal autoantigen. Structure and tissue localization.

A 450-kDa human epidermal autoantigen was originally identified as a protein that reacted with the serum from an individual with a subepidermal blistering disease. Molecular cloning of this protein has now shown that it contains 5065 amino acids and has a molecular mass of 552 kDa. As reported previously this protein, which we call epiplakin, belongs to the plakin family, but it has some very unusual features. Epiplakin has 13 domains that are homologous to the B domain in the COOH-terminal region of desmoplakin. The last five of these B domains, together with their associated linker regions, are particularly strongly conserved. However, epiplakin lacks a coiled-coil rod domain and an amino-terminal domain, both of which are found in all other known members of the plakin family. Furthermore, no dimerization motif was found in the sequence. Thus, it is likely that epiplakin exists in vivo as a single-chain structure. Epitope mapping experiments showed that the original patient's serum recognized a sequence unique to epiplakin, which was not found in plectin. Immunofluorescence staining revealed the presence of epiplakin in whole sheets of epidermis and esophagus, in glandular cells of eccrine sweat and parotid glands and in mucous epithelial cells in the stomach and colon.

Amino Acid Sequence↗
PubMed2001

Percutaneous ulnar artery approach for coronary angiography: a preliminary report in nine patients.

The radial artery approach is becoming more popular for diagnostic cardiac catheterization and interventional procedures because of its lower incidence of access site complications and decreased patient discomfort after the procedure. However, Allen's test reveals inadequate blood supply through the ulnar artery to the hand, and therefore the approach does not seem to be suitable in 10%-30% of patients. Here we demonstrated a new percutaneous ulnar artery approach for coronary angiography in nine patients. We succeeded in obtaining an entry site into the left ulnar artery in seven patients. The average time for cannulation and that for catheterization procedure were comparable with those of the radial approach previously reported from other laboratories. Complications such as bleeding, loss of an ulnar pulse, ulnar nerve injury, and the formation of an aneurysm or fistula were not observed in any patient. The ulnar approach may be another technique that decreases patient discomfort and risk, while preserving the radial artery as a potential coronary bypass graft for surgical myocardial revascularization. Cathet Cardiovasc Intervent 2001;53:410-414.

Adult↗
PubMed2001

A simple tool to identify asian women at increased risk of osteoporosis.

Patients with low bone mineral density (BMD) have a high risk of future fractures, and should be actively considered for treatment to reduce their risk. However, BMD measurements are not widely available in some communities, because of cost and lack of equipment. Simple questionnaires have been designed to help target high-risk women for BMD measurements, thereby avoiding the cost of measuring women at low risk. However, such tools have previously focused on evaluation of non-Asian women. We collected information about numerous risk factors from postmenopausal Asian women in eight countries in Asia using questionnaires, and evaluated the ability of these risk factors to identify women with osteoporosis as defined by femoral neck BMD T-scores < or =-2.5. Multiple variable regression analysis and item reduction yielded a final tool based on only age and body weight. This risk index had a sensitivity of 91% and specificity of 45%, with an area under the curve of 0.79. Previously published risk indices based on larger numbers of variables performed similarly well in this Asian population. Large differences in risk were identified using our index to create three categories: 61% of the high-risk women had osteoporosis, compared with only 15% and 3% of the intermediate- and low-risk women, respectively. The low-risk group represented 40% of all women, for whom BMD measurements are probably not needed unless important risk factors, such as prior nonviolent fracture or corticosteroid use, are present. An existing population-based sample of postmenopausal Japanese women was used to validate our index. In this sample of Japanese women the sensitivity was 98% and specificity was 29%; the low-risk category, for whom BMD is probably unnecessary, represented 25% of all women. We conclude that our index performed well for classifying the risk of osteoporosis among postmenopausal Asian women and applying it would result in more prudent use of BMD technology.

Absorptiometry, Photon↗
PubMed2001

Japanese fermented soybean food as the major determinant of the large geographic difference in circulating levels of vitamin K2: possible implications for hip-fracture risk.

Increasing evidence indicates a significant role for vitamin K in bone metabolism and osteoporosis. In this study, we found a large geographic difference in serum vitamin K2 (menaquinone-7; MK-7) levels in postmenopausal women. Serum MK-7 concentrations were 5.26 +/- 6.13 ng/mL (mean +/- SD) in Japanese women in Tokyo, 1.22 +/- 1.85 in Japanese women in Hiroshima, and 0.37 +/- 0.20 in British women. We investigated the effect of Japanese fermented soybean food, natto, on serum vitamin K levels. Natto contains a large amount of MK-7 and is eaten frequently in eastern (Tokyo) but seldom in western (Hiroshima) Japan. Serum concentrations of MK-7 were significantly higher in frequent natto eaters, and natto intake resulted in a marked, sustained increase in serum MK-7 concentration. We analyzed the relation between the regional difference in natto intake and fracture incidence. A statistically significant inverse correlation was found between incidence of hip fractures in women and natto consumption in each prefecture throughout Japan. These findings indicate that the large geographic difference in MK-7 levels may be ascribed, at least in part, to natto intake and suggest the possibility that higher MK-7 level resulting from natto consumption may contribute to the relatively lower fracture risk in Japanese women.

Aged↗
PubMed2001

The amino acid region 248-382 of the Epstein-Barr virus nuclear protein 2 (EBNA2) is responsible for the EBNA2-induced EBV reactivation.

We showed previously that Epstein-Barr virus (EBV) latency is disrupted and the virus-replicative cycle is activated after expression of EBNA2 in the Burkitt's lymphoma-derived Akata cells. Here, an EBNA2 deletion mutant lacking the amino acid residues 248-382, including the region responsible for association with RBP-J kappa, was generated and tested for its ability to activate EBV replication in Akata cells. This mutant was shown clearly deficient in inducing the EBV-replicative cycle, suggesting that association with RBP-J kappa is necessary for the EBV activating function of EBNA2. It is thus likely that EBV activation by EBNA2, seemingly in conflict with its involvement in lymphocyte immortalization, is nevertheless based on the standard mechanism of transactivation by the protein.

Cell Line↗