Biomedical subjects
Publications and source records attributed to Yoshio Kobayashi.
Coronary remodeling and plaque composition were compared between focal and diffuse coronary lesions. Negative remodeling and fibrous and calcified plaque compositions contribute to stenosis development in diffuse lesions more frequently than in focal lesions.
A previously proposed method based on soap-free emulsion polymerization with an amphoteric initiator for producing micrometer-sized polystyrene particles was extended to application with methyl methacrylate (MMA). The aggregation and dispersion stability of polymer particles, which have ionizable groups arising from initiator radicals, can be controlled by adjusting the pH of the reaction system accompanied with the addition of ionic monomer. Polymerizations were carried out with 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] tetrahydrate amphoteric initiator, NH(3)/NH(4)Cl pH buffer, and sodium p-styrenesulfonate anionic monomer (NaSS) in ranges of MMA concentration (0.58-2.32 kmol/m(3) H(2)O) and NH(3) concentration (2.5-20 mol/m(3) H(2)O) at fixed concentrations of 5 mol/m(3) H(2)O initiator, 10 mol/m(3) H(2)O NH(4)Cl, and 1 mol/m(3) H(2)O NaSS at 65 degrees C. The addition of NaSS during the polymerization could improve stability in dispersion of particles, which coagulated in the absence of NaSS after the disappearance of monomer drops. An increase in the monomer concentration in the present method could enlarge the particle size without lowering the monodispersity of the particle size distribution. On the other hand, an increase in NH(3) concentration decreased the particle size. The highest monodispersity of particle sizes was obtained at a NH(3) concentration of 5 mol/m(3) H(2)O, which gave an average size of 1.5 microm and a coefficient of variation of particle size distribution of 2.2% that was much smaller than the standard criterion for monodispersity, 10%.
OBJECTIVES: The present study evaluated clinical outcomes in diabetic patients after multivessel stenting. BACKGROUND: Multivessel angioplasty studies have reported decreased survival in diabetic patients undergoing conventional balloon angioplasty compared with coronary artery bypass graft surgery (CABG). However, several studies have demonstrated excellent procedural success and acceptable clinical outcomes after multivessel stenting. METHODS: Multivessel stenting was performed in 689 patients with 1,639 native coronary lesions. Patients were classified into three groups according to diabetes mellitus (DM) status: 1) no DM (501 patients/1,200 lesions); 2) DM treated with oral agents (102 patients/235 lesions); and 3) DM treated with insulin (86 patients/204 lesions). RESULTS: Procedural success was high overall. In-hospital CABG was higher in diabetics treated with insulin compared with the other two groups (3.5% vs. 0.4% vs. 1.0%, p = 0.02). There were no significant differences in the incidence of in-hospital cardiac death and myocardial infarction. Diabetic patients treated with oral agents or insulin had higher one-year target lesion revascularization rates than non-diabetic patients (25% vs. 35% vs. 16%, p < 0.001). Lower one-year survival was observed in diabetic patients treated with either oral agents or insulin, compared with non-diabetic patients (85% vs. 86% vs. 95%, p < 0.001). On multivariable analysis, DM was an independent predictor of one-year mortality, myocardial infarction, and target lesion revascularization after multivessel stenting. CONCLUSIONS: Despite a high technical success rate of multivessel stenting, diabetic patients, especially those treated with insulin, have higher in-hospital CABG, higher subsequent revascularization rates, and lower one-year survival than non-diabetic patients.
Larger final lumen dimensions after percutaneous coronary interventions in native coronary arteries lead to lower restenosis rates. We sought to determine the impact of stent expansion, as assessed by intravascular ultrasound, on clinical results of stent implantation in saphenous vein grafts (SVGs). We identified 226 consecutive patients who underwent intravascular ultrasound-guided stenting of 234 de novo SVG lesions. Patients were divided into 2 groups based on the final stent cross-sectional area (CSA): group I (stent CSA <100% of the reference lumen CSA, n = 176 patients, 182 lesions) and group II (stent CSA >/=100% of the reference lumen CSA, n = 50 patients, 52 lesions). Baseline patient characteristics were similar between the 2 groups with the exception of smaller lesions in group II. More aggressive stent expansion (group II) was associated with (1) increased rates of in-hospital non-Q-wave myocardial infarction (29% vs 17%, p = 0.05), (2) any myocardial infarction (26% vs 8%, p = 0.003) at 1-year follow-up, and (3) no improvement in target vessel revascularization at 1 year (31% vs 26%, p = 0.3). Aggressive stent expansion in SVG lesions resulted in higher myocardial infarction rates and, unlike native arteries, no improvement in target vessel revascularization rate at 1 year. A less aggressive stent implantation strategy in SVGs than in native coronary lesions appears prudent.
BACKGROUND: We used intravascular ultrasound (IVUS) to evaluate recurrence after sirolimus-eluting stent (SES) implantation treatment of in-stent restenosis (ISR). METHODS AND RESULTS: Forty-eight ISR lesions (41 patients with objective evidence of ischemia) were treated with SES. Recurrent ISR was identified in 11 lesions (all focal); repeat revascularization was performed in 10. These were compared with 16 patients (19 lesions) without recurrence as documented by angiography. Nine of 11 recurrent lesions had a minimum stent area (MSA) <5.0 mm2 versus 5 of 19 nonrecurrent lesions (P=0.003); 7 of 11 recurrent lesions had an MSA <4.0 mm2 versus 4 of 19 nonrecurrent lesions (P=0.02); and 4 of 11 recurrent lesions had an MSA <3.0 mm2 versus 1 of 19 nonrecurrent lesions (P=0.03). A gap between SESs was identified in 3 of 11 recurrences versus 1 of 19 nonrecurrent lesions. CONCLUSIONS: Stent underexpansion is a significant cause of failure after SES implantation treatment of ISR.
The treatment of in-stent restenosis using balloon angioplasty alone often produces excellent early results, but is associated with high rate of recurrence. Previous studies have demonstrated significant tissue reintrusion shortly after the treatment of in-stent restenosis with balloon angioplasty. The study was designed to elucidate the contribution of early lumen loss 6 hr after balloon angioplasty to lumen loss at follow-up. We prospectively performed quantitative coronary angiography and intravascular ultrasound in 12 patients with in-stent restenosis before intervention, after the final procedure, 6 hr later (5.6 +/- 1.4 hr), and at follow-up (7.7 +/- 2.3 months). Compared with immediately after balloon angioplasty, by 6 hr postintervention, the minimum lumen diameter (MLD) and lumen cross-sectional area had decreased significantly (2.48 +/- 0.44 to 2.01 +/- 0.57 mm, P = 0.01, and 7.0 +/- 1.2 to 5.5 +/- 1.4 mm2, P = 0.004, respectively). Furthermore, the MLD decreased further between 6 hr postintervention and long-term follow-up (2.01 +/- 0.57 to 1.55 +/- 0.64 mm; P = 0.001). Patients who showed recurrence of restenosis at follow-up had greater early lumen loss than patients without recurrence of restenosis (0.71 +/- 0.31 vs. 0.23 +/- 0.13 mm; P = 0.006). Diffuse lesions had greater early lumen loss compared to focal lesions (0.75 +/- 0.35 vs. 0.28 +/- 0.13 mm; P = 0.008). Early lumen loss is common after the treatment of in-stent restenosis by balloon angioplasty. Within the first 6 hr postintervention, 32% +/- 29% of acute lumen gain is lost, and early lumen loss contributed to 42% +/- 18% of total lumen loss at follow-up.
This case report demonstrates subacute luminal narrowing 20 days after balloon angioplasty in the left anterior descending coronary artery due to an intramural hematoma. Stenting was performed and resulted in side-branch compromise caused by squeezing the hematoma from the left anterior descending coronary artery into the left circumflex artery. Another stent was deployed to treat the stenosis in the left circumflex artery.
BACKGROUND: Various autopsy and intravascular ultrasound (IVUS) studies have shown neointimal proliferation as the main mechanism of in-stent restenosis (ISR) responsible for >95% of luminal narrowing while stent struts are not compressed. ISR of diffuse type has a high incidence of recurrence (up to 70%) after balloon angioplasty (PTCA). Tissue ablation with percutaneous rotational coronary atherectomy (PRCA) may be more efficacious compared to tissue compression or extrusion after PTCA for the interventional treatment of diffuse ISR. METHODS: The Rotational Atherectomy Versus Balloon Angioplasty for Diffuse In-Stent Restenosis (ROSTER) trial is a single-center, randomized trial comparing PRCA to PTCA (both with IVUS guidance) in the treatment of diffuse ISR in 200 patients. In the PRCA group (n = 100), rotablation was performed using a burr-to-artery ratio >0.7 followed by adjunctive balloon dilatation at low pressure (4-6 atm). In the PTCA group (n = 100), high-pressure (>12 atm) balloon dilatation was performed using an optimal size balloon. The study's primary end point was target lesion revascularization (TLR) at 9 months and secondary end points included clinical events at 1 year and angiographic restenosis in a substudy of the last 75 patients enrolled. RESULTS: Baseline clinical and angiographic variables were comparable between the 2 groups with similar procedural and angiographic success, but a higher rate of repeat stenting occurred in the PTCA group (31% vs 10%; P <.001). Although the angiographic acute luminal gain was similar between the 2 groups, IVUS analysis revealed lower residual intimal hyperplasia area after PRCA versus PTCA (2.1 +/- 0.9 mm2 vs. 3.3 +/- 1.8 mm2; P =.005). At a mean follow-up of 12 +/- 2 months, there were 2 deaths, 3 myocardial infarctions, and 3 coronary artery bypass graft procedures in each group. TLR incidence was 32% in the PRCA group and 45% in the PTCA group (P =.042), with a similar trend noted in the angiographic substudy. CONCLUSION: The ROSTER trial for diffuse ISR revealed both PRCA and PTCA to be safe and effective, but PRCA resulted in less residual intimal hyperplasia, lower repeat stent use, and decreased TLR.
Intracoronary brachytherapy is a promising modality for inhibition of in-stent restenosis. However, there is a concern of late progression after brachytherapy. This case report describes delayed restenosis after brachytherapy.
We report a patient with bacterial translocation-associated sepsis who was healthy and did not have any related-background. The 57-year-old male had been well until 16 hours before admission, when nausea and vomiting gradually developed and increased in intensity. In the morning of May 22, 2002, he had shaking chills, temperature of 38.6 degrees C and watery diarrhea, and was admitted to Kawasaki Municipal Hospital. On admission, temperature was 40.7 degrees C but otherwise physical examination revealed no particular abnormality. Laboratory data showed total white blood cells of 28,400/microliter, platelet count of 130,000/microliter, creatinine of 2.0 mg/dl and C-reactive protein of 7.5 mg/dl. 1 g of cefmetazole was administered every eight hours. In the early morning of May 23, he suddenly went into shock. At that time, laboratory findings revealed total white blood cells of 33,700/microliter, platelet count of 65,000/microliter, C-reactive protein of 24.9 mg/dl, creatinine of 5.6 mg/dl and serum potassium concentration of 5.7 mEq/l. Gram positive cocci and gram negative rods were isolated from blood culture obtained on admission. Cefmetazole was changed to 1.5 g/day of imipenem/cilastatin sodium and 600 mg/day of clindamycin. In addition, hemodialysis and endotoxin removal with an adsorbent column using polymyxin B were performed. Bacteria detected in the blood on admission were identified as Klebsiela oxytoca and Enterococcus faecium. Imipenem/cilastatin sodium and clindamycin were continued for 13 days. The patient recovered fully and was discharged on June 11. This case suggests that bacterial translocation-associated sepsis might occur even in a hitherto healthy adult.
The effects of habitual cigarette smoking on cardiorespiratory responses to sub-maximal and maximal work were evaluated in nine adult nonsmokers and nine smokers with a mean age of 33 yr. A maximal treadmill test was followed by three tests at 45, 60 and 75% of each subject's VO(2)max. Compared to nonsmokers, the habitual smokers had a non-significantly lower VO(2)max in L/min and per lean body mass (9 and 6%, respectively), but had higher %fat (p<0.01), resulting in a significantly lower VO(2)max per kg body wt (13%, p<0.03). Maximal exercise ventilation (V(E)) was 16% lower in smokers. During sub-maximal work at equivalent exercise stress levels in the two groups, the V(E)/VO(2) ratio was higher in smokers by an average of 11% because VO(2) was lower and the respiratory exchange ratio values were significantly elevated in smokers at 75% of VO(2)max. Blood lactate concentrations in smokers were higher as workloads increased and O(2) pulse (VO(2)/HR) was significantly lower throughout, indicating reduced O(2) extraction, probably due to carbon monoxide. The resting HR was significantly higher in smokers and the HR recovery following all three submaximal exercises was significantly slower in smokers. These results show that detrimental cardiorespiratory effects of chronic cigarette smoking in apparently healthy individuals are evident at moderate exercise levels as reduced gas exchange efficiency in lungs and muscles.
The bacterial strains isolated from 491 patients diagnosed as having urinary tract infections (UTIs) in 13 institutions in Japan were supplied between August 2002 and July 2003. The susceptibilities of them to many kinds of antimicrobial agents were investigated. Of them, 578 strains were estimated as causative bacteria and used for the investigation. The number of them was 578 strains consisting of 177 gram-positive bacterial strains (30.6%) and 401 gram-negative bacterial strains (69.4%). Against Staphylococcus aureus, vancomycin (VCM) showed a strong activity and prevented the growth of all strains with 1 microg/mL. The susceptibility of Staphylococcus epidermidis to cephems including cefotiam (CTM) was relatively good. Against Enterococcus faecalis, ampicillin (ABPC), imipenem (IPM), and VCM showed the strongest antibacterial activity (MIC90: 2-4 microg/mL). In addition, the low sensitive strains (MIC: > or = 256 microg/mL) to clarithromycin (CAM) were detected at 48.3% but none to cefozopran (CZOP). The antibacterial activity of cephems to Escherichia coli was generally good, and especially CZOP and cefpirome (CPR) showed the highest activity (MIC90: < or = 0.125 microg/mL). Quinolone resistant E. coli was detected at frequency of 13.5%, which was higher than that in the last year. The antibacterial activity of cephems to Citrobacter freundii was generally low but CZOP and CPR had a strong acitivity (MIC90: 0.25 and 0.5 microg/mL, respectively). The antibacterial activity of cephems to Klebsiella pneumoniae was good and especially cefmenoxime (CMX), cefixime (CFIX), flomoxef (FMOX), CPR, and CZOP showed stronger activity (MIC90: < or = 0.125 microg/mL). Against Serratia marcescens, meropenem (MEPM) had the highest antibacterial activity followed by CPR and CZOP. Against Proteus mirabilis, CMX, ceftazidime (CAZ), CPR, MEPM, carumonam (CRMN), and levofloxacin (LVFX) showed the strongest activity (MC90: < or = 0.125 microg/mL). Among other cephems, CZOP and CFIX were also strong (MIC90: 0.25 microg/mL). The antibacterial activity of the drugs to Pseudomonas aeruginosa was generally low, and MIC90 of all the drugs were ranged from 64 to > or = 256 microg/mL except IPM and amikacin (AMK) having 16 microg/mL. The antibacterial activity of CZOP was relatively good (MIC50: 8 microg/mL).
A total of 615 bacterial strains isolated from 491 patients diagnosed as having urinary tract infections (UTIs) in 13 institutions in Japan were supplied between August 2002 and July 2003. Then, the clinical background of patients were investigated such as sex, age, and type of infections and kind of bacteria, frequency of bacteria isolation by age and infections, bacteria and infections by timing of antibiotics administration, and bacteria and infections by surgical procedures. The bacterial strains were divided by 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. In the present time, the bacteria most frequently isolated were Escherichia coli. Pseudomonas aeruginosa and Enterococcus faecalis were also relatively frequently isolated. E. coli decreased and P. aeruginosa increased with the complication of the infections. E. faecalis tended to be isolated more frequently in the complicated UTIs than in the uncomplicated 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, accounting for 70.8% in 20-49 years old. In the complicated UTIs without indwelling catheter, the isolation frequency of E. coli decreased with aging of the patients and was lower than that of E. faecalis in the patients aged 70 or more (18.3 vs 20.6%). 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, E. coli decreased and P. aeruginosa increased after the administration in any 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 was more in the patients with surgery in any UTIs. E. faecalis was more frequently isolated in the patients with surgery in uncomplicated and complicated UTIs without indwelling catheter and in the patients without surgery in complicated UTIs with indwelling catheter.
The bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella spp. and Pseudomonas aeruginosa) isolated from patients diagnosed as urinary tract infections (UTIs) in 13 institutions in Japan were supplied between August 2002 and July 2003. 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 1993 and 2001. 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. The drug sensitivity of E. faecalis in this year also was similar to those in up to the previous year. The drug sensitivity of E. coli in this year was generally good except penicillins and was similar to those in up to the previous year. Among cephems, cefozopran (CZOP) and cefpirome (CPR) showed the highest potency (MIC90: < or = 0.125 microg/mL). An antibacterial activity of cefotiam (CTM) was similar to it in 10 years ago and was fine (MIC90: < or = 1 microg/mL). The sensitivity of E. coli to carbapenems and carumonam (CRMN) also was good like to CZOP. However, the sensitivity of the complicated UTIs group to quinolones decreased after 2000 and was suggested to develop the resistance to the drug. The drug sensitivity of Klebsiella spp. in this year also was similar to those in up to the previous year. The bacteria showed good susceptibility (MIC: < or = 0.125 microg/mL) to cefmenoxime (CMX), CPR, cefixime (CFIX), flomoxef (FMOX), and CZOP among cephems. The drug sensitivity of P. aeruginosa was generally low. Most of the bacteria were little sensitive to cephems except CZOP and ceftazidime (CAZ). The sensitive bacteria to CZOP and ceftazidime (CAZ) were observed to be 26.8% (15/56 strains) and 39.3% (22/56 strains) in complicated UTIs group, respectively. The sensitivity profile of P. aeruginosa to the other tested drugs was not much different from that in up to the previous year. However, the sensitivity of the bacteria to carbapenems tended to decrease after 2000, and the low sensitive strains (MIC: > or = 256 microg/mL) were detected at 22.2% (2/9 strains) in the uncomplicated UTIs group and 3.6% (2/56 strains) in the complicated UTIs group.
OBJECTIVES: We sought to determine the impact of aggressive stent expansion on creatine kinase-MB isoenzyme (CK-MB) release and clinical restenosis. BACKGROUND: Elevation of CK-MB after percutaneous coronary interventions has been associated with late mortality. METHODS: We identified 989 consecutive patients who underwent intravascular ultrasound-guided stenting of 1,015 coronary lesions. Patients were divided into three groups according to stent expansion, defined as the ratio of final lumen over the reference lumen cross-sectional areas: Group 1 (ratio <70%, n = 117 patients with 126 lesions); Group 2 (ratio 70% to 100%, n = 551 patients with 562 lesions); Group 3 (ratio >100%, n = 321 patients with 327 lesions). RESULTS: The peak CK-MB values increased significantly with increasing stent expansion: CK-MB = 3 to 5x normal occurred 16%, 18%, and 25% in Groups 1, 2, and 3, respectively, p = 0.02; CK-MB >5 times normal occurred 9%, 13%, and 16% respectively, p = 0.02. Conversely, at one year follow-up there was a stepwise decrease in target lesion revascularization (11% vs. 19% and 17%, respectively, p = 0.04) and major adverse cardiac events with increasing stent expansion. In addition, there was a trend toward lower mortality in Group 3 (9% vs. 4.4% vs. 4.0%, p = 0.07). CONCLUSIONS: Intravascular ultrasound-guided stent overexpansion (final lumen greater than reference lumen cross-sectional area) is accompanied by a higher periprocedural CK-MB release but a lower target lesion revascularization and a trend toward lower mortality at one year. Increased periprocedural CK-MB release appears as a trade-off for optimal stent implantation and lower clinical restenosis.
In-stent restenosis lesions were divided into 2 groups according to the use of cutting balloon (n = 76) or conventional balloon angioplasty (n = 407) before gamma-brachytherapy. Cutting balloon angioplasty, compared with conventional balloon angioplasty, in patients undergoing gamma-brachytherapy for in-stent restenosis is associated with less requirement for new stents (11% vs 22%, p = 0.02) but similar target vessel revascularization (35.1% vs 29.8%, p = 0.4) at follow-up.
Despite similar early clinical events, patients who undergo treatment of small vessels are at an increased risk for target lesion revascularization (TLR) after coronary artery stenting. We sought to determine predictors of TLR after stent implantation in small coronary arteries. We identified 423 consecutive patients who underwent intravascular ultrasound (IVUS)-guided small vessel stenting procedures in 465 coronary lesions with an angiographic reference vessel diameter of <2.75 mm. Patients were divided into 2 groups based on a final IVUS lumen area of < or =6.0 mm2 (n=345 lesions, group I) and >6.0 mm2 (n=115, group II). Baseline patient characteristics and in-hospital outcomes were similar between the 2 groups, except for a higher rate of restenotic lesions in group I and bifurcation lesions in group II. Group I had higher TLR rates at 1 year compared with group II patients (39% vs 26%, p = 0.02). The TLR rate appeared to decrease with greater stent expansion, especially at >90% of the reference vessel area, as assessed by IVUS. By multivariate analysis, an IVUS final stent area of < or =6 mm2, diabetes, absence of prior myocardial infarction, and history of intervention were independent predictors of 1-year TLR in this population. Final stent area of >6.0 mm2 and greater stent expansion were associated with a decrease in TLR. Therefore, there does not appear to be any "downside" to aggressive stent implantation strategies in small vessels. In contrast, IVUS allows maximization of final lumen dimensions to minimize clinical restenosis.
BACKGROUND: It is not clear why some plaque ruptures lead to acute coronary syndromes (ACS) but others do not. METHODS AND RESULTS: We analyzed 80 plaque ruptures in 74 patients and compared culprit lesions of ACS patients with nonculprit lesions of ACS patients and lesions of non-ACS patients; both culprit and nonculprit plaque ruptures were studied in 6 of 54 ACS patients. Intravascular ultrasound findings suggesting thrombus were observed more frequently in culprit lesions of ACS patients (n=35) compared with nonculprit lesions of ACS patients (n=19) and lesions of non-ACS patients (n=26): 60% versus 32% versus 8% (P<0.001). At the minimal lumen site, smaller lumen areas (3.3+/-1.5 versus 5.4+/-2.6 versus 6.1+/-2.0 mm2, P<0.001) and greater area stenosis (61+/-15% versus 50+/-14% versus 46+/-18%, P=0.002) and plaque burden (80+/-8% versus 71+/-8% versus 69+/-10%, P<0.001) were observed in culprit lesions of ACS patients compared with nonculprit lesions of ACS patients and lesions of non-ACS patients. Lesions were longer (18.7+/-6.4 versus 154.9+/-6.1 versus 12.0+/-4.9 mm, P<0.001) and rupture site remodeling indices were greater (1.26+/-0.21 versus 1.24+/-0.21 versus 1.09+/-0.05, P=0.002). Independent predictors of culprit plaque ruptures in ACS patients were smaller minimum lumen areas (P=0.02) and presence of thrombus (P=0.01). CONCLUSIONS: Ruptured plaques in culprit lesions of ACS patients have smaller lumens; greater plaque burdens, area stenosis, and remodeling indices; and more thrombus. Plaque rupture itself does not lead to symptoms. The association of plaque rupture with a smaller lumen area and/or thrombus formation causes lumen compromise and leads to symptoms.