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Biomedical subjects

Masaya Miyazaki

Publications and source records attributed to Masaya Miyazaki.

16 recordsLinked to original sources
PubMed2006

Microchannel enzyme reactors and their applications for processing.

Microreaction technology is an interdisciplinary field combining science and engineering. It has attracted the attention of researchers from different fields for the past few years, resulting in the development of several microreactors. Enzymes are one of the catalysts used in microreactors: they are useful for substance production in an environmentally friendly way and have high potential for analytical applications. However, few enzymatic processes have been commercialized because of problems with stability and the cost and efficiency of the reactions. Thus, there have been demands for innovation in process engineering, particularly for enzymatic reactions, and microreaction devices can serve as efficient tools for the development of enzyme processes. In this review, we summarize the recent advances of enzyme-immobilized microchannel reactors; fundamental techniques for micro enzyme-reactor design and important applications of this multidisciplinary technology in chemical processing are also included in our topics.

Bioreactors↗
PubMed2006

Radiologic removal and replacement of port-catheter systems for hepatic arterial infusion chemotherapy.

OBJECTIVE: The purpose of our study was to retrospectively evaluate the safety and efficacy of radiologic removal and replacement of port-catheter systems. MATERIALS AND METHODS: Between January 1999 and December 2004, 532 patients with unresectable advanced liver cancer underwent radiologic placement of port-catheter systems at our institution. Of these, 18 patients (nine men and nine women; age range, 32-83 years; mean age, 53.8 years) underwent removal of an implanted port-catheter system via the right femoral artery and radiographically guided replacement with a new system to allow continuous hepatic arterial infusion chemotherapy; we retrospectively reviewed these 18 cases. The reasons for removal of the previously implanted systems were as follows: catheter dislodgement (n = 15), catheter obstruction (n = 1), infection related to the implanted port (n = 1), and hemodynamic change (n = 1). Digital subtraction angiography and CT were performed, usually during injection of contrast medium through the implanted port-catheter system, within a few days after the replacement procedure and every 3 months thereafter. RESULTS: We successfully performed radiologic removal and replacement of the portcatheter system while the patient was under local anesthesia in all 18 patients without complications requiring treatment. The cumulative patency rates of the hepatic artery after removal of the old port-catheter system and replacement with a new port-catheter system were 87.8% and 64.1% at 6 months and 1 year, respectively. Hepatic arterial infusion chemotherapy after replacement was performed 0-68 times (median, 19 times). CONCLUSION: When an implanted port-catheter system can no longer be used but the patency of the hepatic artery is confirmed and continuous hepatic arterial infusion chemotherapy is required, removal and replacement of the port-catheter system are recommended.

Adult↗
PubMed2005

Immobilization of enzymes on a microchannel surface through cross-linking polymerization.

A novel and facile method for the preparation of an enzyme-immobilized microreactor has been developed in which enzymes are immobilized as an enzyme-polymer membrane formed on the inner wall of the microchannel by a cross-linking polymerization method; the resulting microreactor shows excellent reaction performance and stability against denaturating agents.

Biosensing Techniques↗
PubMed2005

Specific molecule localization in microchannel laminar flow and its application for non-immobilized-probe analysis.

Microfluidic systems enable superior control of fluidics. We have developed a novel size-separation method utilizing secondary flow within a microchannel. Using confocal fluorescence microscopy and computer simulation, we confirmed that separation occurred as a result of specific molecular localization in the curving part of the microchannel. Maximum separation efficiency was achieved by optimizing microchannel design and flow rate for individual separation targets. In addition, more effective separation was achieved by use of plural microchannel curves. This method was used for sequence-selective DNA sensing. Double-stranded DNA formed by hybridization between target DNA and a complementary probe had different elution profiles from those of the single-stranded non-complementary sequence. Moreover, the response depends on the length of the DNA molecules. This method does not require immobilization of either probe or target DNA, because all reactions occurred in the solution phase. Such features may reduce experimental error and the difference between data from different operators.

Biosensing Techniques↗
PubMed2005

Controllable polymerization of N-carboxy anhydrides in a microreaction system.

We have developed a microfluidic system for polymerization of amino acid N-carboxyanhydride and compared the properties of the products with those obtained by batchwise system under various experimental conditions. It was found that the microreactor produced polymers with narrower molecular weight distribution compared with polymers obtained by the batchwise system. Also, the molecular mass of the polymer produced using the microreactor was simply governed by the flow (pumping) rate. These results indicated that the microreactor could be a model for synthesis of amino acid polymer with highly controllable average molecular weight and molecular weight distribution.

Journal Article↗
PubMed2005

Efficient immobilization of enzymes on microchannel surface through His-tag and application for microreactor.

We developed a simple immobilisation method for His-tagged enzymes on a microchannel surface. It facilitates immobilisation of protein molecule on microchannel surface through Ni-complex, using crude or purified protein solutions. By this method, we could immobilize proteins on microcapillary constantly. This method might be useful for further development of microreactor with reversibly immobilized enzymes.

Animals↗
PubMed2004

Direct observation of long-strand DNA conformational changing in microchannel flow and microfluidic hybridization assay.

Conformational control of macromolecules is useful for efficient chemical and biochemical reactions. This article reports a direct observation method for macromolecules, such as long-strand DNA, in microchannel flow as well as a simple method for stretching DNA strands by microfluidics. Stretching and orientation of DNA molecules by control of flow within a microchannel was observed by optical microscopy. This DNA stretching is explained by coil-stretch transition of polymer molecules. This technique is useful for creating chemical reactions with macromolecules. It offers high selectivity and efficiency that are impossible to achieve in bulk solution. We also demonstrate that our microfluidic stretching method can accomplish efficient hybridization of long-strand DNA. This method will be useful for direct hybridization assay of long-strand DNA.

DNA↗
PubMed2004

Application of a microfluidic reaction system for CdSe nanocrystal preparation: their growth kinetics and photoluminescence analysis.

We used a microreactor for CdSe nanocrystal preparation and explored the effects of experimental conditions on the properties of the products. The particle growth kinetics and photoluminescence properties of the nanocrystals showed identical trends to previous reports, indicating the efficiency of the current method for analysis of rapid nanocrystal synthesis as well as industrial production of CdSe nanocrystals.

Journal Article↗
PubMed2004

[Cryoglobulinemia].

Explore the source record for details and available documents.

Adrenal Cortex Hormones↗
PubMed2003

Continuous synthesis of CdSe-ZnS composite nanoparticles in a microfluidic reactor.

ZnS-coated CdSe composite particles have been continuously synthesized in a microfluidic reactor. By using this system, CdSe particles and a ZnS coating can be produced in sequence, and the particle size and layer thickness can be directly adjusted by the residence time. It demonstrated that the continuous synthesis in the microreactor was a simple and efficient way to prepare composite particles with different structures and determine the optimized experimental conditions.

Journal Article↗
PubMed2003

Sequence-selective DNA detection using multiple laminar streams: a novel microfluidic analysis method.

On-site detection methods for DNA have been demanded in the pathophysiology field. Such analysis requires a simple and accurate method, rather than high-throughput. This report describes a novel microfluidic analysis method and its application for simple sequence-selective DNA detection. The method uses a microchannel device with a serpentine structure. Sequence-specific binding of probe DNA can be detected at one side of the microchannel. This method is capable of sequence-specific detection of DNA with high accuracy. Single base mutations can also be analyzed. Combination of laminar stream and laminar secondary flow in the microchannel enable specific detection of probe-bound DNA.

Base Sequence↗
PubMed2003

Modified micro-space using self-organized nanoparticles for reduction of methylene blue.

By using silica layers bound to the surface of the inner wall of the microchannel via a self-assembly technique which relies on capillary forces to organize the colloids, TiO2 particles were attached to the inner surface of a microcapillary. The reduction rate of methylene blue increased by more than 150 times in the SiO2/TiO2 modified micro-space compared to that in a batch system.

Journal Article↗
PubMed2003

Synthesis of chemotactic peptide analogs with a photoaffinity cross-linker as new probes for analysis of receptor-ligand interaction.

Formylpeptide receptors are well-characterized receptors which participate in host defense responses of neutrophils. We designed and synthesized chemotactic peptide analog with p-benzoylphenylalanine (Bpa) and biotin to probe structural and mechanistic aspects of peptide-receptor interaction. These peptides possess biological activities which were dependent upon spacer residue length of and Bpa position. The covalent photoaffinity label was detected by Streptavidine-blot, which was inhibited by the parent peptide.

Biotin↗
PubMed2002

Preparation of CdSe nanocrystals in a micro-flow-reactor.

A micro-reactor was utilized for continuous and controlled CdSe nanocrystal preparation. Effects of reaction conditions on optical properties of the nanocrystals were investigated; in this current system, rapid and exact temperature control of the micro-reactor was beneficial for controlling particle diameter and reproducible preparation of particles; additional effort was made towards narrower particle-size distributions.

Journal Article↗