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Biomedical subjects

Atsushi Aoki

Publications and source records attributed to Atsushi Aoki.

6 recordsLinked to original sources
PubMed2006

[Left ventricular free wall rupture in an elderly patient; report of a case].

We successfully repaired left ventricular free wall rupture in a 91-year-old woman. She was admitted to our hospital because of consciousness loss. Blood pressure was only 60 mmHg on arrival. Contrast-enhanced computed tomography (CT) demonstrated massive pericardial effusion and transmural contrast defect of the left ventricular lateral wall in the delayed phase. Upon surgery there was massive clot around the heart. A localized infracted area on the left ventricular lateral wall was exposed using off-pump coronary artery bypass (OPCAB) technique. There was mild bleeding only during diastolic phase. Three mattress sutures of 3-0 prolene with Teflon felt strips were placed to control the bleeding under beating heart. A sheet of collagen and fibrin glue was also applied. Postoperative course was uneventful. This type of left ventricular rupture could be less invasively repaired by off-pump technique. As far as we investigated, this is the oldest patient of ventricular free wall rupture successfully repaired.

Aged, 80 and over↗
PubMed2005

Fabrication of polymer Langmuir-Blodgett films containing regioregular poly(3-hexylthiophene) for application to field-effect transistor.

Semiconducting thin films consisting of regioregular poly(3-hexylthiophene) (RR-PHT) and poly(N-dodecylacrylamide) (pDDA) were constructed by the Langmuir-Blodgett (LB) technique. A mixture of RR-PHT and pDDA spread from a chloroform solution on a water surface forms a stable monolayer, which can be transferred onto solid substrates by the LB method, yielding a well-defined polymer LB film. Surface morphology studies of the LB film indicate that the RR-PHT is dispersed uniformly throughout the surface. The polymer thin film was chemically doped by contacting with FeCl3 acetonitrile solution, and a conductivity of 5.6 S/cm was achieved. Further, the LB film was utilized as the semiconducting film in the field-effect transistor (FET), and mobilities of 2.2 x 10(-4) and 4.4 x 10(-4) cm2 V(-1) s(-1) were obtained by analyzing the saturated and linear regions of the current-voltage characteristic, respectively.

Journal Article↗
PubMed2005

Modified boron neutron capture therapy for malignant gliomas performed using epithermal neutron and two boron compounds with different accumulation mechanisms: an efficacy study based on findings on neuroimages.

OBJECT: To improve the effectiveness of boron neutron capture therapy (BNCT) for malignant gliomas, the authors used epithermal rather than thermal neutrons for deep penetration and two boron compounds-sodium borocaptate (BSH) and boronophenylalanine (BPA)-with different accumulation mechanisms to increase the boron level in tumors while compensating for each other's faults. METHODS: Thirteen patients, 10 of whom harbored a glioblastoma multiforme (GBM), one a gliosarcoma, one an anaplastic astrocytoma, and one an anaplastic oligoastrocytoma, were treated using this modified BNCT between January 2002 and December 2003. Postoperatively, neuroimaging revealed that only one patient with a GBM had no lesion enhancement postoperatively. The patients underwent 18F-BPA positron emission tomography, if available, to assess the accumulation and distribution of BPA before neutron radiotherapy. The neutron fluence rate was estimated using the Simulation Environments for Radiotherapy Applications dose-planning system before irradiation. The patients' volume assessments were performed using magnetic resonance (MR) imaging or computerized tomography (CT) scanning. Improvements in the disease as seen on neuroimages were assessed between 2 and 7 days after irradiation to determine the initial effects of BNCT; its maximal effects were also analyzed on serial neuroimages. The mean tumor volume before BNCT was 42.3 cm3. Regardless of the pre-BNCT tumor volume, in every patient harboring an assessable lesion, improvements on MR or CT images were recognized both at the initial assessment (range of volume reduction rate 17.4-71%, mean rate 46.4%) and at follow-up assessments (range of volume reduction rates 30.3-87.6%, mean rate 58.5%). More than 50% of the contrast-enhanced lesions disappeared in eight of the 12 patients during the follow-up period. CONCLUSIONS: This modified BNCT produced a good improvement in malignant gliomas, as seen on neuroimages.

Adult↗
PubMed2004

Molecular optical gating devices based on polymer nanosheets assemblies.

We describe here a polymer nanosheet assembly that serves as a molecular photoswitching and optical exclusive OR (EXOR) logic gate. Separate polymer nanosheets (monolayers) containing phenanthrene, anthracene, and dinitrobenzene chromophore were prepared by the Langmuir-Blodgett technique (LB films). A bilayer-couple, consisting of phenanthrene (sensitizer) monolayer and dinitrobenzene (acceptor) monolayer, and the other couple, of anthracene monolayer and dinitrobenzene monolayer, were confirmed to function as a photodiode showing current rectification on light irradiation. The two photodiodes are connected as each photocurrent direction becomes opposite. In the polymer photodiode array (LB films), anodic photocurrent was observed when the anthracene was selectively excited. On the other hand, cathodic photocurrent was observed by selective excitation of the phenanthrene. Moreover, the output photocurrent displayed a very small value when the phenanthrene and anthracene were excited simultaneously. The performance is discussed for this gate's application to an optical EXOR logic gate.

Journal Article↗
PubMed2002

Photocurrent amplification by an energy/electron transfer cascade in polymer Langmuir-Blodgett films.

Effective photocurrent generation by visible light irradiation on hetero-deposited polymer Langmuir-Blodgett (LB) films containing tris(bipyridine) ruthenium(II) (Ru(bpy)3(2+)) and anthracene derivatives was observed. The photocurrent amplification was found to be assisted by the photoinduced energy/electron transfer cascade, which consists of the interlayer triplet-triplet energy transfer process from photoexcited Ru(bpy)3(2+) to anthracene, and then electron transfer processes from the triplet anthracene to a viologen acceptor, from Ru(bpy)3(2+) to the oxidized anthracene and from the electrode to Ru(bpy)3(3+).

Journal Article↗