Biomedical subjects

Yoshihiro Takeda

Publications and source records attributed to Yoshihiro Takeda.

25 records · Page 2Linked to original sources

PubMed2003

Nanoscale soldering of metal nanoparticles for construction of higher-order structures.

We demonstrated that platinum nanoparticles dispersed in pure water were "soldered" by gold into higher-order structures such as "nanowebs". In practice, gold nanoparticles in water containing the platinum nanoparticles were melted by irradiation of a pulsed 532-nm laser, which excites selectively the surface plasmon band of the gold nanoparticles, and the melted gold nanoparticles solder the platinum nanoparticles together into the nanowebs. Optical absorption spectroscopy and electron microscopy together with electron probe microanalysis were employed to observe the structure of the nanowebs and to elucidate their formation dynamics.

Journal Article↗

PubMed2003

Quantitative evaluation by Tl-201 scintigraphy in the diagnosis of thyroid follicular nodules.

We examined the diagnostic capability of a quantitative evaluation by determining the optimum area for comparisons with nodule and optimum imaging time by Tl-201 scintigraphy in thyroid follicular nodules, retrospectively. Ninety-one thyroid follicular nodules, for which the pathological diagnosis had been established, were examined (60 benign, 31 malignant). After 74 MBq of Tl-201 chloride was injected intravenously, Tl-201 scintigrams were obtained at 10, 20, 30, and 120 min. For the quantitative evaluation, the area with the greatest accumulation in the nodule and a comparative region in the contralateral thyroid and the soft tissues in the cervical region were manually selected as the region of interest (ROI) referring to Tc-99m pertechnetate scintigrams and ultrasonographic findings as a guide by two radiologists, and the T/N ratio (tumor/normal tissue ratio) and T/S ratio (tumor/soft tissue ratio) were calculated. The pixel counts were determined for all ROI. A summary index of overall test performance can be calculated as the area under the receiver operating characteristic (ROC) curve (Area (Az)), and the likelihood ratios were also calculated. We estimated the cut-off on a fitted binormal ROC curve. Multiple regression analyses were used to investigate the relationships between the optimum quantitative evaluation and 5 independent variables. A p value below 5% was considered to be significant. The T/N ratio and T/S ratio were significantly higher in the malignant group at 10 min (0.844 and 0.702), 20 min (0.844 and 0.704), 30 min (0.841 and 0.670), and 120 min (0.887 and 0.733), respectively (p < 0.01). The Az for the T/N ratio was greatest at 120 min. The multiple regression analysis showed that only 'benign or malignant' was a significant variable in the T/N ratio at 120 min. It correlated significantly in interobserver (r = 0.80) and intraobserver (r = 0.80) studied (p < 0.001). An assessment of the cut-off value of the T/N ratio at 120 min, at the cut-off of 1.255, the likelihood ratio for positive test result was greatest at 8.56, while at the cut-off of 1.010, the likelihood ratio for negative test result was lowest at 0.165. The T/N ratio at 120 min was more useful than the other condition to distinguish between benign and malignant thyroid follicular nodules.

Adenocarcinoma, Follicular↗

PubMed2003

Effect of plaque debulking before stent implantation on in-stent neointimal proliferation: a serial 3-dimensional intravascular ultrasound study.

BACKGROUND: Recent intravascular ultrasound (IVUS) studies have suggested that plaque burden has a role in promoting intimal hyperplasia after stenting. We report on volumetric assessments of in-stent neointimal formation with 3-dimensional IVUS analysis, comparing directional coronary atherectomy (DCA) plus stenting (DCA/stenting) to stenting without DCA. METHODS: Twenty-four patients (24 lesions) treated with DCA before stenting were matched to 24 patients (24 lesions) receiving stenting without DCA. All stents were a single Multilink stent. In both groups, serial IVUS was performed before and after intervention and during the 6-month follow-up period. The arterial segments that were analyzed with a computer-based contour detection program were the same as the stented segments analyzed on serial studies. These measurements were obtained: (1) lumen volume (LV), (2) stent volume (SV), (3) vessel volume (VV), (4) in-stent neointimal volume (ISV) calculated as SV-LV, and (5) percent in-stent neointimal volume (%ISV) calculated as ([SV-LV]/SV) x 100. RESULTS: Baseline characteristics of the 2 groups were similar. After intervention, both groups achieved similar LV (140.0 mm(3) DCA/stenting vs 135.2 mm(3) stenting alone). However, the follow-up ISV and %ISV were significantly smaller in the DCA/stenting group (19.6 +/- 12.2 mm(3) DCA/stenting vs 44.6 +/- 29.5 mm(3) stenting alone; P =.00040; 15.3% +/- 10.6% DCA/stenting vs 31.5% +/- 17.7% stenting alone; P =.00040). Consequently, the DCA/stenting group showed a significantly greater follow-up LV (121.0 +/- 51.5 mm(3) DCA/stenting vs 91.5 +/- 26.7 mm(3) stenting alone; P =.016). CONCLUSIONS: Plaque removal with DCA before stenting inhibits in-stent neointimal hyperplasia.

Aged↗

PubMed2003

Cleavage of stretched DNA on glass by histones observed with fluorescence microscopy.

A stretched single lambda DNA molecule labeled with TOTO-1 dye molecules was immobilized on a cover slip by casting a solution of DNA-lipid polyion complex containing TOTO-1 dye, and were loaded with an aqueous solution of histone. Fluorescence microscopy applied to the single DNA showed that (1) the TOTO-1 dye molecules intercalated in the stretched DNA molecule were vertically aligned almost completely with respect to the DNA axis, and (2) the stretched DNA was cleaved by interaction with histone molecules.

DNA↗

PubMed2003

Percutaneous transluminal septal myocardial ablation for hypertrophic obstructive cardiomyopathy.

Percutaneous transluminal septal myocardial ablation (PTSMA) is a new therapeutic option for patients with hypertrophic obstructive cardiomyopathy (HOCM). In the present study, the acute and follow-up results of PTSMA were evaluated. From August 1997 to March 2003 27 medically refractory patients (New York Heart Association (NYHA) functional class 2.9+/-0.6) with HOCM underwent PTSMA. The target septal branch was determined by probationary ballooning in 3 and by myocardial contrast echocardiography in 24 patients. The mean resting left ventricular outflow tract pressure gradient (PG) was reduced from 70+/-44 to 24+/-22 mmHg (p<0.0001); the peak concentration of creatine kinase was 1545+/-686 IU/L. Although transient trifascicular block was observed in 14 patients, permanent pacemaker implantation was not required. There were no major adverse cardiac events during the hospital stay; the mean clinical follow-up was 2.2+/-1.7 years. Repeated PTSMA was needed in 1 patient; however, symptomatic improvement had been well preserved in all patients (NYHA class 1.2+/-0.4). Follow-up echocardiographic examination showed sustained improvement in PG, septal and left ventricular posterior wall thicknesses, and the grade of systolic anterior movement and regurgitation of the mitral valve. In conclusion, PTSMA is a safe and effective therapeutic option for medically refractory patients with HOCM.

Adult↗

PubMed2002

Debulking and stenting versus debulking only of coronary artery disease in patients treated with cilostazol (final results of ESPRIT).

Stenting inhibits vascular constrictive remodeling after directional coronary atherectomy (DCA). Cilostazol has been reported to control neointimal proliferation after stenting. This study's aim was to examine the effect of debulking and stenting with antirestenotic medication on restenosis. After optimal DCA, 117 lesions were randomly assigned to either the DCA with stent (DCA-stent) (58 lesions) group or the DCA only (59 lesions) group. Multilink stents were implanted in the DCA-stent group. Cilostazol (200 mg/day) without aspirin was administered to both groups for 6 months. Ticlopidine (200 mg/day) was given to the DCA-stent group for 1 month. Serial quantitative angiography and intravascular ultrasound (IVUS) were performed at the time of the procedure and at 6-month follow-up. The primary end point was 6-month angiographic restenosis. Clinical event rates at 1 year were also assessed. Baseline characteristics were similar. All procedures were successful. No adverse effects to cilostazol were observed. Postprocedural lumen diameter was significantly larger (3.27 vs 2.92 mm; p <0.0001) in the DCA-stent group. However, the follow-up lumen diameter was not significantly different (2.53 vs 2.41 mm, DCA-stent vs DCA). IVUS revealed that intimal proliferation was significantly larger in the DCA-stent group (4.2 vs 1.5 mm(2); p <0.0001), which accounted for the similar follow-up lumen area (6.5 vs 7.1 mm(2)). The restenosis rate was low in both groups (5.4% vs 8.9%), and the difference was not significant. Clinical event rates at 1 year were also not significantly different. These results suggest that optimal lesion debulking by DCA does not always need adjunctive stenting if cilostazol is administered.

Aged↗

PubMed2002

The usefulness of serum thyroglobulin levels and Tl-201 scintigraphy in differentiating between benign and malignant thyroid follicular lesions.

OBJECTIVE: To compare the diagnostic capabilities of various serum thyroglobulin levels (Tg) and Tl-201 scintigraphy with regard to thyroid follicular lesions. METHODS: We examined 80 thyroid follicular lesions (benign: 55, malignant: 25) in patients with nodular goiter for whom a pathological diagnosis was made based on surgical findings. Tg was measured by an I-125 (radioimmunoassay) method. In Tl-201 scintigraphy, 74 MBq of Tl-201 chloride was intravenously injected and imaged after 10 minutes (early image) and after 120 minutes (delayed image), and the scintigrams were evaluated both visually and quantitatively, with special attention paid to the part of the nodule with the highest accumulation of Tl-201 chloride. The cutoff levels of Tg for categorizing the lesions as malignant were set at 40, 100, 300, 500, 1,000 and 2,500 microg/l. In Tl-201 scintigraphy, method I involved high uptake on both early and delayed images, method 2 involved high uptake on only the early image, and method 3 involved high uptake on only the early image or the same accumulation in comparison with the normal region on the early image, with no washout being quantitatively judged as indicative of malignancy. A summary index of overall test performance can be calculated as the area under the receiver operating characteristic (ROC) curve (Area (Az)). Likelihood ratios for several cutoff levels were also calculated. RESULTS: In the diagnosis, Az of Tl-201 (0.95),was larger than that of Tg (0.65). The sensitivity and accuracy of Tg at each cutoff level (sensitivity: 4.0% to 76.0%, accuracy: 50.0% to 72.5%) were lower than with Tl-201 scintigraphy (methods 1-3, sensitivity: 76.0-100%, accuracy: 77.5-88.8%). The likelihood ratio for the positive results of method 1for Tl-201 scintigraphy, were greatest in the present study (13.9), and the likelihood ratio for the negative results of method 3 for Tl-201 scintigraphy, (0) was smallest in the present study. CONCLUSION: Diagnosis based on Tl-201 washout patterns in which quantitative evaluation is combined with visual evaluation appears to be more useful for the differentiation of malignant thyroid follicular lesions than diagnosis by Tg.

Adolescent↗