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Biomedical subjects

Yoshio Kobayashi

Publications and source records attributed to Yoshio Kobayashi.

At least 19 recordsLinked to original sources
PubMed2006

Feasibility and safety of granulocyte colony-stimulating factor treatment in patients with acute myocardial infarction.

BACKGROUND: This study examined feasibility and safety of granulocyte colony-stimulating factor (G-CSF) treatment for patients with acute myocardial infarction (AMI). METHODS: Forty patients with AMI related with the left anterior descending coronary artery, who underwent successful percutaneous coronary intervention (PCI), were randomized into G-CSF group (n=18) or Control group (n=22). G-CSF treatment was started within 24 h after PCI. 99mTc-tetrofosmin single-photon emission computed tomography (SPECT) was performed at 4 days and 6 months after AMI. SPECT data was analyzed for LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), LV ejection fraction (LVEF) and myocardial perfusion. RESULTS: LVEF at 6 months was significantly better than that at 4 days in G-CSF group (p=0.013), but not changed in Control group (p=0.245). Although no significant difference was observed for LVEDV between the two groups, LVESV tended to be decreased only in G-CSF group. In G-CSF group, defect score (DS) was significantly decreased from 4 days to 6 months after AMI. Restenosis rate at 6 months after AMI was not significantly different between the two groups. CONCLUSIONS: G-CSF treatment for patients with AMI was effective and did not have any clinical and angiographic adverse effects.

Aged↗
PubMed2006

Coronary aneurysm reduced after coronary stenting.

We describe as case of a 70-year-old man who underwent a percutaneous coronary intervention with stenting, for a severe stenosis complicated by a coronary aneurysm just distal to the stenotic site. Notably, coronary angiogram showed an immediate and progressive reduction in the size of coronary aneurysm. Curved planar reconstruction images of the enhanced CT showed no thrombus and no dissection of the coronary aneurysm. We speculate that coronary stenting might decrease the velocity of coronary flow through the stenosis. Consequently, stenting might attenuate the hydrodynamic wall stress on the aneurysm, and, in addition, improve the degradation of the extracellular matrix structure through the regulation of matrix metalloproteinases. Regression of coronary aneurysm after stenting requires further investigations, because stenting may become a potential means for treating post-stenotic aneurysms.

Aged↗
PubMed2006

Occurrence of de novo sustained monomorphic ventricular tachycardia induced after percutaneous transluminal alcohol septal myocardial ablation for hypertrophic obstructive cardiomyopathy.

We report here a 75-year-old male with hypertrophic obstructive cardiomyopathy of de novo sustained monomorphic ventricular tachycardia (VT) after successful percutaneous transluminal alcohol septal myocardial ablation (PTSMA). In this case history, the necrotic induced by the PTSMA procedure might represent a region of slow conduction that is a circuit of re-entry and therefore stimulation might be spread around. Therefore, the basis of the sustained monomorphic VT was thought to be the presence of a focal necrotic area, itself a complication arising from the PTSMA procedures. In conclusion, the PTSMA procedure may have caused a de novo episode of ventricular arrhythmia.

Aged↗
PubMed2006

Remarkable thickening of right atrial wall in subjects with cardiac amyloidosis complicated with sick sinus syndrome.

We observed a 63-year old male with cardiac amyloidosis who presented with the clinical symptoms of sick sinus syndrome and dyspnea and abnormal thickening of the right atrial wall, which extended to the junction of the superior vena cava. This may explain the relationship of abnormal thickening of the right atrium which extends to the junction of the superior vena cava and right atrium with amyloid deposits in the sinus node and occurrence of sick sinus syndrome.

Amyloidosis↗
PubMed2006

Effect of plaque volume on subsequent vessel remodeling at edges of sirolimus-eluting stents.

Serial (baseline and 9-month follow-up) intravascular ultrasound analysis was performed at 5-mm reference segments immediately proximal and distal to the sirolimus-eluting stent (SES) in 33 lesions. Proximal and distal reference segments were divided into 1-mm subsegments. Between postintervention and follow-up intravascular ultrasound studies, there were significant decreases in the lumen and increases in plaque & media areas in the subsegment closest to the distal edge, with no change in external elastic membrane area. There was no significant change in external elastic membrane, lumen, and plaque & media areas within the other subsegments. At the nearest 1-mm subsegment from the proximal and distal edges, baseline plaque & media area was associated with subsequent vessel remodeling. In conclusion, a large amount of plaque at the SES edge may be a risk of negative remodeling at follow-up (stent edge restenosis). It supports the importance of "normal-to-normal" SES deployment.

Aged↗
PubMed2006

Critical roles of muscle-secreted angiogenic factors in therapeutic neovascularization.

The discovery of bone marrow-derived endothelial progenitors in the peripheral blood has promoted intensive studies on the potential of cell therapy for various human diseases. Accumulating evidence has suggested that implantation of bone marrow mononuclear cells effectively promotes neovascularization in ischemic tissues. It has also been reported that the implanted cells are incorporated not only into the newly formed vessels but also secrete angiogenic factors. However, the mechanism by which cell therapy improves tissue ischemia remains obscure. We enrolled 29 "no-option" patients with critical limb ischemia and treated ischemic limbs by implantation of peripheral mononuclear cells. Cell therapy using peripheral mononuclear cells was very effective for the treatment of limb ischemia, and its efficacy was associated with increases in the plasma levels of angiogenic factors, in particular interleukin-1beta (IL-1beta). We then examined an experimental model of limb ischemia using IL-1beta-deficient mice. Implantation of IL-1beta-deficient mononuclear cells improved tissue ischemia as efficiently as that of wild-type cells. Both wild-type and IL-1beta-deficient mononuclear cells increased expression of IL-1beta and thus induced angiogenic factors in muscle cells of ischemic limbs to a similar extent. In contrast, inability of muscle cells to secrete IL-1beta markedly reduces induction of angiogenic factors and impairs neovascularization by cell implantation. Implanted cells do not secret angiogenic factors sufficient for neovascularization but, instead, stimulate muscle cells to produce angiogenic factors, thereby promoting neovascularization in ischemic tissues. Further studies will allow us to develop more effective treatments for ischemic vascular disease.

Aged↗
PubMed2006

Preparation and characterization of long-lived anode catalyst for direct methanol fuel cells.

Entry of direct methanol fuel cells into the market requires anode catalyst with stable activity. This paper presents a novel method for stabilizing the activity by immobilizing silica on the catalytic PtRu nanoparticles. Characterization was performed by STEM-EDX, XRD, and ICP. The silica-immobilized PtRu nanoparticles showed high and stable activity toward methanol oxidation. The activity was maintained for 1000 h in sulfuric acidic solution, while the activity of the catalyst with "bare" PtRu nanoparticles decayed after 100 h, showing high durability of the silica-immobilized PtRu nanoparticles catalyst in quasi-anodic acidic environment.

Journal Article↗
PubMed2006

Stent deformity caused by coronary artery spasm.

Previous studies have shown that coronary stents have radial strength above the pressure induced by coronary artery spasm. This case report describes a stent deformity caused by coronary artery spasm during percutaneous coronary intervention.

Angioplasty, Balloon, Coronary↗
PubMed2006

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2004). I. Susceptibility distribution].

The bacterial strains isolated from 490 patients diagnosed as having urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2004 and July 2005. The susceptibilities of them to many kinds of antimicrobial agents were measured. Of them, 577 strains were estimated as causative bacteria and used for the measurement. The strains consisted of 156 gram-positive bacterial strains (27.0%) and 421 gram-negative bacterial strains (73.0%). Against Staphylococcus aureus, arbekacin (ABK), vancomycin (VCM) showed the strongest activity and prevented the growth of all strains with 2 microg/mL. Against Enterococcus faecalis, ampicillin (ABPC) and VCM showed a strong antibacterial activity. The antibacterial activity of cephems to Escherichia coli was generally good, and especially cefozopran (CZOP) and cefpirome (CPR) showed the strongest activity (MIC90: < or = 125 microg/mL). Quinolone resistant E. coli [MIC of ciprofloxacin (CPFX): > or = 4 microg/mL] was detected at frequency of 18.8%, which was higher than that in the last year. Against Klebsiella pneumoniae, CZOP, meropenem (MEPM), and carumonam (CRMN) showed the strongest activity and prevented the growth of all strains with 0.125 microg/mL or less. The antibacterial activity of the other cephems was relatively good, and decrease in their activity observed in the last year study was not recognized. Against Serratia marcescens, imipenem (IPM) and gentamicin (GM) had the strongest antibacterial activity. Against Proteus mirabilis, CRMN showed the strongest activity and prevented the growth of all strains with 0.125 microg/mL or less. MEPM prevented the growth of all strains with 0.25 microg/mL. Next, cefmenoxime (CMX), ceftazidime (CAZ), CZOP, cefixime (CFIX), cefpodoxime (CPDX), and cefditoren (CDTR) showed a strong activity. The antibacterial activity of the drugs to Pseudomonas aeruginosa was generally low, and MIC90 of all the drugs was ranged from 32 to > 128 microg/mL except IPM and MEPM having 16 microg/mL. The antibacterial activities of CZOP and CAZ were considered to be relatively good on MIC50 comparison (MIC50: 2 microg/mL).

Aminoglycosides↗
PubMed2006

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2004) II. Background of patients].

Six hundred six bacterial strains isolated from 490 patients diagnosed as having urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2004 and July 2005. The frequency of bacteria isolation stratified with patient clinical background was compared. The clinical background investigated included sex, age, type of infections, timing of antibiotics administration, and presence or absence of surgery affecting a decrease in defense against infection. The bacterial strains were stratified with the age and sex of the patients and the types of infections. In males, the number of patients aged less than 60 years was few and the complicated UTIs without indwelling catheter was observed most frequently. In females, the number of patients aged less than 60 years was comparatively more than in males. In all of ages except 0-19 and > or = 80 years, the ratio of the uncomplicated UTIs was high, accounting for 44.1-90.0% of all types of infections. In the present time, the bacteria most frequently isolated were Escherichia coli. Pseudomonas aeruginosa and Enterococcus faecalis also were relatively frequently isolated. E. coli most frequently isolated with the uncomplicated UTIs and P. aeruginosa and E. faecalis most frequently isolated with the complicated UTIs. With respect to the relation of these results to the age of the patients, in the uncomplicated UTIs, the isolation frequency of E. coli was the highest in all age groups except 0-19 years, accounting for 50% or higher. In the complicated UTIs without indwelling catheter, the isolation frequency of E. coli tended to be high in all age groups. In the complicated UTIs with indwelling catheter, P. aeruginosa were more frequently isolated. In comparison of causative bacteria in UTIs between before and after the administration of antibiotics, P. aeruginosa increased after the administration in any types of UTIs. In comparison of causative bacteria in UTIs with or without surgery, E. coli was more frequently isolated in the patients without surgery, while P. aeruginosa and E. faecalis were more frequently isolated in the patients with surgery in any UTIs.

Adult↗
PubMed2006

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2004). III. Secular changes in susceptibility].

The bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella spp. and Pseudomonas aeruginosa) isolated from patients diagnosed as urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2004 and July 2005. The susceptibilities of these bacteria to various antimicrobial agents were measured. The bacteria were divided into 2 groups consisting of uncomplicated UTIs and complicated UTIs (with and without indwelling catheter) based on their isolation origins. The results were compared with those obtained between 1995 and 2003. The drug sensitivity of S. aureus in this year was similar to those in up to the previous year and S. aureus showed the best susceptibility to vancomycin (VCM) and arbekacin (ABK). The drug sensitivity of E. faecalis in this year also was similar to those in up to the previous year. The susceptibility of E. coli to cephems in this year was generally good and was similar to those in up to the previous year. MIC90 of cefozopran (CZOP) was the most stable and 0.125 microg/mL or less since 1995. The susceptibility of E. coli to cefpirome (CPR) and cefotiam (CTM) also was good but to cefaclor (CCL), cefixime (CFIX), and cefpodoxime (CPDX) was largely decreased in complicated UTI groups. The sensitivity of E. coli to carbapenems also was good but to carumonam (CRMN) tended to decrease. The susceptibility of E. coli to quinolones, however, has largely changed and has decreased since 2003 in uncomplicated UTIs and 2000 in complicated UTIs. That was suggested the development of the resistance to the drug. The susceptibility of Klebsiella spp. to cefazolin (CEZ), CTM, CCL, CPDX, and cefditoren (CDTR) decreased in the previous year and recovered to the year before the previous year in this year. The susceptibility of Klebsiella spp. to other cephems was stable since 1995, especially against CZOP, the highest sensitivity (MIC90: < or = 0.125 microg/mL) was maintained. The susceptibility of Klebsiella spp. to carbapenems and CRMN also was good. The susceptibility of Klebsiella spp. to aminoglycosides was lower than to CZOP but was stable since 1995. The susceptibility of P. aeruginosa was generally low and has largely changed against the majority of the agents since 1995. The susceptibility of P. aeruginosa isolated from uncomplicated UTIs has largely changed against ceftazidime (CAZ), cefsulodin (CFS), CZOP, imipenem (IPM), meropenem (MEPM), aztreonam (AZT), CRMN, gentamicin (GM), and tobramycin (TOB). The susceptibility of P. aeruginosa isolated from complicated UTIs has largely changed against CSF, CZOP, MEPM, GM, and ciprofloxacin (CPFX). The susceptibility of P. aeruginosa isolated from complicated UTIs has been stable against amikacin (AMK). For annual changes in MIC50, TOB and IPM had a relatively stable and high activity (MIC50: 0.5-2 microg/mL).

Anti-Bacterial Agents↗
PubMed2005

Preparation of highly monodisperse poly(methyl methacrylate) particles incorporating fluorescent rhodamine 6G for colloidal crystals.

Soap-free emulsion polymerization was extended to preparation of monodisperse poly(methyl methacrylate) (PMMA) particles incorporating rhodamine 6G (R6G) fluorescent molecules. The polymerization was conducted in the presence of an anionic monomer, p-styrenesulfonate (NaSS), which improved dispersion stability of the polymer particles. NaSS concentrations was ranged up to 2 mol/m3 H2O in the polymerization at 0.5 kmol/m3 H2O methyl methacrylate (MMA) monomer and 5 mol/m3 H2O potassium persulfate (KPS) initiator for R6G concentrations from 0.1 to 10 mol/m3-polymer. At R6G concentrations lower than 1.0 mol/m3-polymer, PMMA particles were highly monodisperse and incorporated most R6G molecules. The average sizes of PMMA particles were in a rage of 160-300 nm, and decreased with the concentration of NaSS. The high monodispersity of the particles enabled the fabrication of colloidal crystals of the particles with a vertical deposition method.

Journal Article↗
PubMed2005

Oxidizing intermediates from the sterically hindered iron salen complexes related to the oxygen activation by nonheme iron enzymes.

Oxidizing intermediates are generated from nonheme iron(III) complexes to investigate the electronic structure and the reactivity, in comparison with the oxoiron(IV) porphyrin pi-cation radical (compound I) as a heme enzyme model. Sterically hindered iron salen complexes, bearing a fifth ligand Cl (1), OH(2) (2), OEt (3), and OH (4), are oxidized both electrochemically and chemically. Stepwise one-electron oxidation of 1 and 2 generates iron(III)-mono- and diphenoxyl radicals, as revealed by detailed spectroscopic investigations, including UV-vis, EPR, Mössbauer, resonance Raman, and ESIMS spectroscopies. In contrast to the oxoiron(IV) formation from the hydroxoiron(III) porphyrin upon one-electron oxidation, the hydroxo complex 4 does not generate oxoiron(IV) species. Reaction of 2 with mCPBA also results in the formation of the iron(III)-phenoxyl radical. One-electron oxidation of 3 leads to oxidative degradation of the fifth EtO ligand to liberate acetaldehyde even at 203 K. The iron(III)-phenoxyl radical shows high reactivity for alcoxide on iron(III) but exhibits virtually no reactivity for alcohols including even benzyl alcohol without a base to remove an alcohol proton. This study explains unique properties of mononuclear nonheme enzymes with Tyr residues and also the poor epoxidation activity of Fe salen compared to Mn and Cr salen compounds.

Ethylenediamines↗
PubMed2005

Preparation and colloidal stability of monodisperse magnetic polymer particles.

A previously proposed method was examined for producing monodisperse, submicrometer-sized magnetic polymer particles. The method applies soap-free emulsion polymerization during which Fe3O4 magnetic nanoparticles are heterocoagulated onto precipitated polymer nuclei. To chemically fix the magnetic particles to the polymer nuclei, vinyl groups were introduced on the Fe3O4 particles in a preliminary surface modification reaction with methacryloxypropyltrimethoxysilane, and methacryloxypropyldimethoxysilane (MPDMS) was added to reaction systems of the soap-free emulsion polymerization. The colloidal dispersion stability of magnetic polymer particles was improved by the addition of an ionic monomer, sodium p-styrenesulfonate (NaSS), during the polymerization. The polymerizations were carried out with styrene monomer and potassium persulfate initiator in ranges of NaSS concentrations (0-2.4 x 10(-3) M), NaSS addition times (60-80 min), and monomer concentrations (0.3-0.6 M) at fixed concentrations of 1.6 x 10(-2) M initiator and 1.3 x 10(-2) M MPDMS for pH 4.5 adjusted with a buffer system of [CH3COOH]/[NaOH]. The addition of NaSS during the polymerization could maintain the dispersion stability of magnetic polymer particles during the polymerization. Selection of the reaction conditions enabled the preparation of colloidally stable, submicrometer-sized magnetic polymer particles that had coefficients of variation of distribution smaller than the standard criterion for monodispersity, 10%.

Colloids↗
PubMed2005

Preparation and characterization of aqueous colloids of Pt-Ru nanoparticles.

A synthetic method for platinum-ruthenium (PtRu) nanoparticles in aqueous media is proposed. This method employs citric acid as a capping agent and NaBH(4) as a reducing agent with the aid of pH control. The number-averaged size of the PtRu nanoparticles was ca. 2 nm. The crystal phase and chemical composition of the nanoparticles was investigated by X-ray diffraction measurement and scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis, which indicated that the nanoparticles mainly consisted of an alloy of Pt and Ru. Electrochemical measurement showed that the PtRu nanoparticles had catalytic activity for methanol oxidation.

Alloys↗
PubMed2005

Synthesis of submicrometer-sized titania spherical particles with a sol-gel method and their application to colloidal photonic crystals.

A synthetic method for preparing submicrometer-sized titania particles is proposed, which is based on hydrolysis of titanium alkoxide with the use of a cosolvent and an amine catalyst for alkoxide hydrolysis. The preparation was performed with different amines of ammonia, methylamine (MA), and dimethylamine (DMA) in different solvents of ethanol/acetonitrile, ethanol/methanol, ethanol/acetone, ethanol/acetonitrile, and ethanol/formamide for 0.1-0.3 M water and 0.03 M titanium tetraisopropoxide (TTIP) at temperatures of 10-50 degrees C. The use of the ethanol/acetonitrile solvent with MA was required for preparing monodispersed, spherical particles. The number average of the titania particle sizes and their coefficient of variation were varied from 143 to 551 nm and from 5.7 to 20.6%, respectively, with reaction temperature and concentrations of water and MA. Colloidal crystals of titania particles fabricated with a sedimentation method revealed reflection peaks attributed to Bragg's diffraction. Annealing at 100-1000 degrees C led to shrinkage and crystallization of titania particles followed by an increase in the refractive index of titania particles.

Journal Article↗