Biomedical subjects

Yoshio Kobayashi

Publications and source records attributed to Yoshio Kobayashi.

At least 37 records · Page 2Linked to original sources

PubMed2005

Silica coating of silver nanoparticles using a modified Stober method.

Silver nanoparticles prepared through a borohydride-reduction method were directly coated with silica by means of a seeded polymerization technique based on the Stober method. Various amine catalysts were used for initialization of a sol-gel reaction of TEOS with no need for a prior surface modification. Use of dimethylamine (DMA) as a catalyst was found to be necessary to obtain a proper coating. The silica shell thickness was varied from 28 to 76 nm for TEOS concentrations of 1-15 mM at 11.1 M water and 0.8 M DMA. The optical spectra of the core-shell silver-silica composite particles show a qualitative agreement with predictions by Mie theory.

Journal Article↗

PubMed2005

Deposition of gold nanoparticles on silica spheres by electroless metal plating technique.

A previously proposed method for metal deposition with silver [Kobayashi et al., Chem. Mater. 13 (2001) 1630] was extended to uniform deposition of gold nanoparticles on submicrometer-sized silica spheres. The present method consisted of three steps: (1) the adsorption of Sn(2+) ions took place on surface of silica particles, (2) Ag(+) ions added were reduced and simultaneously adsorbed to the surface, while Sn(2+) was oxidized to Sn(4+), and (3) Au(+) ions added were reduced and deposited on the Ag surface. TEM observation, X-ray diffractometry, and UV-vis absorption spectroscopy revealed that gold metal nanoparticles with an average particle size of 13 nm and a crystal size of 5.1 nm were formed on the silica spheres with a size of 273 nm at an Au concentration of 0.77 M.

Journal Article↗

PubMed2005

Intravascular ultrasound assessment of lesions with target vessel failure after sirolimus-eluting stent implantation.

Intravascular ultrasound (IVUS) evaluation was performed in 33 lesions with sirolimus-eluting stent (SES) failure: 4 thromboses, 26 in-stent restenoses (including 6 edge stenoses), 4 new stenoses >5 mm proximal to the stent, and 1 patient with no evidence of the implanted SES (presumably because of embolization). A minimum stent area <5.0 mm(2) (stent underexpansion) was observed in 67% of all SES failures (in particular, 67% of intrastent restenosis); negative remodeling was observed in 4 of 6 stent edge restenoses, and new lesions were secondary to an increase in plaque area.

Coronary Restenosis↗

PubMed2005

Creatine kinase-MB enzyme elevation and long-term clinical events after successful coronary stenting in lesions with ruptured plaque.

Patients with acute coronary syndrome are at increased risk of acute and long-term events after stent implantation. We compared the impact of intravascular ultrasound detected plaque rupture on creatine kinase-MB (CK-MB) isoenzyme release and clinical outcomes by comparing 62 patients with ruptured plaques with 62 matched control patients who underwent stent implantation. Two thirds of the patients in each group presented with an acute coronary syndrome. There were no differences in procedural complications between groups, although patients with ruptured plaque had higher CK-MB elevation rates than those without ruptured plaque (1 to 3 times the upper limit of normal CK-MB, 35% vs 10%, p <0.001; >3 times the upper limit, 15% vs 2%, p = 0.02). Independent predictors of CK-MB elevation were presence of ruptured plaque (p = 0.03) and unstable angina (p = 0.04). Patients with ruptured plaque had higher composite rates of late events (target lesion revascularizations/myocardial infarctions/cardiac deaths) than controls (25% vs 9%, p = 0.03). These results were similar when only patients with acute coronary syndrome were studied. Plaque rupture morphology is associated with higher periprocedural CK-MB release and worse 1-year clinical outcome in patients treated with coronary stenting.

Analysis of Variance↗

PubMed2005

Study of the synergism between carbapenems and vancomycin or teicoplanin against MRSA, focusing on S-4661, a carbapenem newly developed in Japan.

S-4661 is a methylcarbapenem antibiotic newly developed in Japan. We evaluated the combined actions of carbapenems, including S-4661 and vancomycin or teicoplanin, against 27 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated from the blood of patients admitted to Keio University Hospital, using the checkerboard technique. The minimum inhibitory concentrations (MICs) were determined by the Mueller-Hinton agar method. Most of the strains were highly resistant to carbapenems. Synergy with S-4661, panipenem, meropenem or imipenem, and vancomycin was detected against 92% of the strains tested. Synergy with S-4661, panipenem, meropenem or imipenem, and teicoplanin was detected against 74% of the strains tested. The results of our study suggest that combination therapy of vancomycin or teicoplanin with any of S-4661, panipenem, meropenem, or imipenem would be effective for severe infections due to MRSA strains that are resistant to carbapenems.

Anti-Bacterial Agents↗

PubMed2005

Effect of a marathon run on serum lipoproteins, creatine kinase, and lactate dehydrogenase in recreational runners.

The objective of this study was to determine the effect of a marathon run on serum lipid and lipoprotein concentrations and serum muscle enzyme activities and follow their recovery after the run. These blood concentrations were measured before, immediately after, and serially after a marathon run in 15 male recreational runners. The triglyceride level was significantly elevated postrace, then fell 30% below baseline 1 day after the run, and returned to baseline after 1 week. Total cholesterol responded less dramatically but with a similar pattern. High-density lipoprotein cholesterol remained significantly elevated and low-density lipoprotein cholesterol was transiently reduced for 3 days after the run. The total cholesterol/high-density cholesterol ratio was significantly lowered for 3 days. Serum lactate dehydrogenase activity significantly doubled postrace and then declined but remained elevated for 2 weeks. Serum creatine kinase activity peaked 24 hr after the run, with a 15-fold rise, and returned to baseline after 1 week. The rise of these enzymes reflects mechanically damaged muscle cells leaking contents into the interstitial fluid. It is concluded that a prolonged strenuous exercise bout in recreational runners, such as a marathon, produces beneficial changes in lipid blood profiles that are significant for only 3 days. However, muscle damage is also evident for 1 week or more from the dramatic and long-lasting effect on enzyme levels. Laboratory values for these runners were outside normal ranges for some days after the race.

Adult↗

PubMed2005

Diabetes mellitus complicated with rapidly progressive glomerulonephritis in an elderly patient.

An 88-year-old man with a 30-year history of type 2 diabetes and a 3-year history of chronic renal failure was admitted for evaluation of anasarca. On admission, findings of nephrotic syndrome and microscopic hematuria were observed. During the course of therapy, rapid deterioration of renal function occurred with the appearance of pneumonia. Irrespective of the therapy with hemodialysis and antibiotics, he died of respiratory failure. The autopsy showed a rare case of rapidly progressive glomerulonephritis (crescentic glomerulonephritis) superimposed on membranous nephropathy. This experience highlighted the importance of the differential diagnosis of non-diabetic glomerulopathy even in elderly patients with diabetes mellitus.

Aged↗

PubMed2005

[The assessment of the reliability and the validity of the EOQOL questionnaire of osteoporotics--QOL assessment of elderly osteoporotics by EOQOL].

We presented a novel and specific questionnaire for quality of life of elderly subjects with osteoporosis (EOQOL), and analyzed its reliability and validity. Based on the discussions with elderly people of osteoporosis, we extracted key words related to complaints of patients with vertebral fractures. A 49 questionnaire was developed on concepts derived from key words. The subdirectories of the questionnaire for elderly osteoporotic subjects consisted of pain, daily activity, movement, physiological activity, duty, recreation and well-being. To analyze the reliability and the validity of EOQOL, it was evaluated in 101 elderly subjects with osteoporosis. Crohnbach's alpha coeffient was 0.82 for pain, 0.86 for daily activity, 0.73 for movement, 0.83 for mood, 0.78 for anxiety against falls, 0.84 for physiological activity, 0.85 for duty, 0.66 for free time, 0.78 for a nice feeling about life. These results indicated that EOQOL is useful as a disease specific questionnaire for elderly osteoporotic patients with osteoporosis.

Activities of Daily Living↗

PubMed2005

[Development of a portable fall risk index for elderly people living in the community].

AIM: To develop a portable risk index for falls. METHODS: Risk factors were chosen from previously established factors then we added several environmental factors to the risk index; previous falls in the last 12 month, trippig or stumbling, inability to ascend or descend stairs without help, decreased walking speed, inability to cross a road within the green signal interval, inability to walk 1km without a break, inability to stand on one leg for 5 seconds (eyes open), using a cane, inability to wring out a towel, dizziness or faintness, stooped or rounded back, knee joint pain, visual disturbance, hearing disturbance, cognitive decline, fear of falling, receiving 5 or more prescribed drugs, sensation of darkness at home, obstacles inside, barrier on the carpet or floor, using steps daily at home, steep slopes around home. SUBJECTS: The questionnaire sheet was completed by 2,439 community-dwelling elderly subjects (76.3 +/- 7.4 years old). The frequency of each items of fall risk index was compared between fallers (history of fall within one year) and non-fallers. Multiple regression analysis was performed to identify independent risk factors for previous falls. RESULTS: Except barrier, step use and steep slope around home, all items in the fall risk index were more frequent in fallers. Multivariate analysis revealed that tripping or stumbling, inability to cross a road within the green signal interval, dizziness or faintness, obstacles inside, inability to wring out a towel, cane use and knee joint pain were independent risk factors for previous falls. These 7 selected items were further analyzed as predictors. The maximum sum of sensitivity and specificity was reached at the cut-off point of 2/3 (sensitivity 0.65, specificity 0.72) by receiver operating curve. CONCLUSION: Portable fall risk index is useful for clinical settings to identify high-risk subjects.

Accidental Falls↗

PubMed2005

[In vitro susceptibilites to levofloxacin and various antibacterial agents of 11,475 clinical isolates obtained from 52 centers in 2002].

The susceptibilities of bacteria to fluoroquinolones (FQs), especially levofloxacin, and other antimicrobial agents were investigated using 11,475 clinical isolates collected in Japan during 2002. Methicillin susceptible staphylococci, Streptococcus pyogenes, Streptococcus pneumoniae, Moraxella catarrhalis, the family of Enterobactericeae, Haemophilus influenzae and Acinetobacter spp. exhibited stable and high susceptibilities to FQs. The rate of FQs-resistant MRSA was 80 approximately 90%, being markedly higher than that of FQs-resistant MSSA. The FQs-resistance rate of MRCNS was also higher than that of MSCNS, however, it was lower than that of MRSA. No FQs-resistant clinical isolates of Salmonella spp. were detected in any of the surveys. Thirteen of Escherichai coli 696 isolates, 8 of Klebsiella pneumoniae 630 isolates and 33 of Proteus mirabilis 373 isolates produced extended-spectrum beta-lactamase (ESBL), furthermore 6 of 13 in E. coli, 1 of 8 in K. pneumoniae and 14 of 31 ESBL-producing isolates, and in P. mirabilis were FQs resistant. Attention should be focused in the future on the emergence of ESBL in relation to FQs resistance. The rate of FQs-resistant P. aeruginosa isolated from urinary tract infection (UTI) was 40 approximately 60%, while 15 approximately 25% of isolates from respiratory tract infection (RTI) were resistant. IMP-1 type metallo beta-lactamase producing organisms were found in 49 of P. aeruginosa 1,095 isolates, 7 of S. marcescens 586 isolates and 4 of Acinetobacter spp. 474 isolates, respectively. Glycopeptide-resistant enterococci or S. aureus was not found.

Anti-Bacterial Agents↗

PubMed2005

[The new concept and diagnostic method of sepsis--not SARS, yes SIRS].

Sepsis is one of the most complicated and common conditions clinicians encounter. The presence of causal bacteria has not been an essential element for sepsis, after the American College of Chest Physicians and the Society of Critical Care Medicine proposed SIRS as the new consensus and concept in 1991. The test kit "Hybrisep", detects pathogens in the blood directly. Effective use of it may be helpful in the further study of sepsis.

Humans↗

PubMed2005

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2003). I. Susceptibility distribution].

The bacterial strains isolated from 565 patients diagnosed as having urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2003 and July 2004. The susceptibilities of them to many kinds of antimicrobial agents were investigated. Of them, 701 strains were estimated as prophlogistic bacteria and used for the investigation. The strains consisted of 258 Gram-positive bacterial strains (36.8%) and 443 Gram-negative bacterial strains (63.2%). Against Staphylococcus aureus, vancomycin (VCM) showed the strongest activity and prevented the growth of all strains with 2 microg/mL. Against Streptococcus agalactiae, ampicillin (ABPC), cefozopran (CZOP), imipenem (IPM), and clarithromycin (CAM) showed a strong activity and the MIC90 was 0.125 microg/mL or less. Against Enterococcus faecalis, VCM, ABPC, and IPM showed a strong antibacterial activity. The antibacterial activity of cephems to Escherichia coli was generally good, and especially CZOP and cefpirome (CPR) showed the strongest activity (MIC90: < or = 0.125 microg/mL). Quinolone resistant E. coli [MIC of ciprofloxacin (CPFX): > or =4 microg/mL] was detected at frequency of 15.7%, which was higher than that in the last year. Against Klebsiella pneumoniae, meropenem (MEPM) showed the strongest activity and next, the antibacterial activity of CRMN and CZOP was good. The antibacterial activity of the other cephems, however, significantly decreased, compared with that evaluated in last year. Against Serratia marcescens, MEPM had the strongest antibacterial activity. Against Proteus mirabilis, MEPM and CRMN showed the strongest activity and prevented the growth of all strains with 0.125 microg/mL or less. Nest, cefmenoxime (CMX), ceftazidime (CAZ), cefixime (CFIX), cefpodoxime (CPDX), CPR, CZOP, 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 < or = 256 microg/mL except IPM and amikacin (AMK) having 16 microg/mL. The antibacterial activity of CZOP was relatively good (MIC50: 2 microg/mL).

Drug Resistance, Microbial↗

PubMed2005

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2003). II. Background of patients].

Seven hundred and nineteen bacterial strains isolated from 565 patients diagnosed as having urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2002 and July 2003. The frequency of bacteria isolation divided 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 divided with the age and sex of the patients and the types of infections. In males, the number of patients aged less than 50 years was few and the complicated UTIs without indwelling catheter was observed most frequently. Number of patients aged 20-39 years was greater in female than male. In all of ages except 0-9 and 70-79 years, the ratio of the uncomplicated UTIs was high, accounting for 44.4-91.7% 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 was most frequently isolated from the uncomplicated UTIs, and P. aeruginosa and E. faecalis were frequently isolated from the complicated UTIs with indwelling catheter. 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, accounting for 40% or higher. In the complicated UTIs without indwelling catheter, the isolation frequency of E. coli decreased with aging of the patients but still was the highest in all age groups. In the complicated UTIs with indwelling catheter, the isolation frequency of E. coli was lower than in the uncomplicated UTIs in all age groups and P. aeruginosa and E. faecalis 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.

Adolescent↗

PubMed2005

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2003). III. Secular changes in susceptibility].

The bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella spp. and Pseudomonas aeruginosa) isolated from 565 patients diagnosed as urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2003 and July 2004. The susceptibilities of these bacteria to various antimicrobial agents were examined. 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 1994 and 2002. The drug sensitivity of S. aureus in this year was similar to those in up to the previous years and S. aureus showed the best susceptibility to vancomycin. The drug sensitivity of E. faecalis in this year also was similar to those in up to the previous years. The drug sensitivity of E. coli in this year was generally good except penicillins and was similar to those in up to the previous years. Among cephems, cefozopran (CZOP) and cefpirome (CPR) showed the highest potency activity (MIC90: < or = 0.125 microg/mL). An antibacterial activity of cefotiam (CTM) was stable for 10 years and was fine (MIC0: < or = 0.5 microg/mL). The sensitivity of E. coli to carbapenems and carumonam (CRMN) also was good like to CZOP. The sensitivity of the complicated UTIs group to quinolones, however, has decreased after 2000 and it was suggested that the resistance to the drug has developed. Kiebsiella spp. showed a decrease in the susceptibility to some of cephems. The drugs indicating a big decrease in the sensitivity were cefazolin, CTM, cefaclor, and cefpodoxime. Imipenem, carbapenems, also indicated a decrease in the sensitivity. The susceptibility of the strain to the other drugs was similar to that in up to the previous years. Among them, CZOP maintained good susceptibility (MIC90: > or = 0.125 microg/mL against uncomplicated UTIs, 0.25 microg/mL against complicated UTIs) like meropenem. The drug sensitivity of P. aeruginosa was generally low and was not much different from that in up to the previous years.

Anti-Infective Agents↗

PubMed2004

Nonuniform strut distribution correlates with more neointimal hyperplasia after sirolimus-eluting stent implantation.

BACKGROUND: Little is known about causes of intimal hyperplasia (IH) after sirolimus-eluting stent (SES) implantation. METHODS AND RESULTS: Intravascular ultrasound was performed in 24 lesions with intra-SES restenosis and a comparison group of 25 nonrestenotic SESs. To assess stent strut distribution, the maximum interstrut angle was measured with a protractor centered on the stent, and the visible struts were counted and normalized for the number of stent cells. In SES restenosis patients, minimum lumen site was compared with image slices 2.5, 5.0, 7.5, and 10.0 mm proximal and distal to this site. The minimum lumen site had a smaller IVUS lumen area at follow-up (2.7+/-0.9 versus 6.2+/-1.9 mm2; P<0.01), larger maximum interstrut angle (135+/-39 degrees versus 72+/-23 degrees; P<0.01), larger IH area (3.4+/-1.5 versus 0.6+/-1.1 mm2; P<0.01) and thickness (0.7+/-0.3 versus 0.1+/-0.2 mm; P<0.01) at maximum interstrut angle, and fewer stent struts (4.9+/-1.0 versus 6.0+/-0.5; P<0.01) even when normalized for the number of stent cells (0.78+/-0.15 versus 0.97+/-0.07; P<0.01). Compared with nonrestenotic SES, the restenosis lesions also had a smaller minimal lumen area, larger IH area, thicker IH at maximum interstrut angle, fewer stent struts, and larger maximum interstrut angle. Multivariate analysis identified the number of visualized stent struts normalized for the number of stent cells and maximum interstrut angle as the only independent IVUS predictor of IH cross-sectional area (P<0.01 and P<0.01), minimum lumen area (P<0.01 and P<0.01), and IH thickness (P<0.01 and P<0.01). CONCLUSIONS: The number and distribution of stent struts affect the amount of neointima after SES implantation.

Aged↗

PubMed2004

Fabrication of sub-micrometer-sized jingle bell-shaped hollow spheres from multilayered core-shell particles.

Jingle bell-shaped hollow spheres were fabricated starting from multilayered particles composed of a silica core, a polystyrene inner shell, and a titania outer shell. Composite particles of silica core-polystyrene shell, synthesized by coating a 339-nm-sized silica core with a polystyrene shell of thickness 238 nm in emulsion polymerization, were used as core particles for a succeeding titania-coating. A sol-gel method was employed to form the titania outer shell with a thickness of 37 nm. The inner polystyrene shell in the multilayered particles was removed by immersing them in tetrahydrofuran. These successive procedures could produce jingle bell-shaped hollow spheres that contained a silica core in the titania shell.

Journal Article↗

PubMed2004

Particle formation in the hydrolysis of tetraethyl orthosilicate in pH buffer solution.

Particle formation in the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) was studied by varying pH (9.5-11) with the basic catalysts NH3, methylamine (MA), and dimethylamine (DMA) in the presence of 5 mol/m3 CH3COOH, which was chosen to suppress time variations of pH and ionic strength during the reaction. Spherical particles were formed for MA and DMA at catalyst concentrations of 0.02-0.2 kmol/m3 and for NH3 at catalyst concentrations of 0.1-1.5 kmol/m3. In a common range of catalyst concentrations for spherical particle formation, average particle size was largest for DMA and smallest for NH3. Hydrolysis rate of TEOS could be quantified by the use of buffer systems as a function of TEOS and OH- concentrations. A specific relation was not found between the hydrolysis and the particle size. The zeta potential of silica particles measured in the reaction solvent was in the order DMA < MA < NH3, and ionic strength, estimated from pH in the reactions, was in the order DMA approximately equal to MA > NH3. This suggested that the particle sizes were controlled by electrostatic particle interactions.

Acetates↗

PubMed2004

Preparation of multilayered gold-silica-polystyrene core-shell particles by seeded polymerization.

A preparation method for multilayered gold-silica-polystyrene core-shell composite particles is proposed. The gold-silica core-shell particles of 192-nm-sized, synthesized by coating the 18-nm-sized gold particles with silica by a seeded growth technique, were used as cores for succeeding polystyrene coating. After surface modification of gold-silica composite particles by methacryloxypropyltrimethoxysilane (MPTMS), polymerizations of styrene (0.16-0.4 M) were conducted with 8 x 10(-3) M of potassium persulfate initiator in the presence of 1 x 10(-3) M of sodium p-styrenesulfonate anionic monomer. Multilayered core-shell gold-silica-polystyrene particles that contained a single core could be obtained. The coefficient of variation of size distribution (CV) of the composite particles was less than 7%, and polystyrene shell thickness was in a range of 193 to 281 nm.

Gold↗