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Kiichi Sato

Publications and source records attributed to Kiichi Sato.

28 records · Page 2Linked to original sources
PubMed2003

Microchip-based chemical and biochemical analysis systems.

This review focuses on chemical and biochemical analysis systems using pressure-driven microfluidic devices or microchips. Liquid microspace in a microchip has several characteristic features, for example, short diffusion distances, high specific interfacial area and small heat capacity. These characteristics are the key to controlling micro unit operations and constructing new integrated chemical systems. By combining multiphase laminar flow and the micro unit operations, such as mixing, reaction, extraction and separation, continuous flow chemical processing systems are realized in the microchip format. By applying these concepts, several different analysis systems were successfully integrated on a microchip. In this paper, we introduce the microchip-based chemical systems for wet analysis of cobalt ion, multi-ion sensors, immunoassay, and cellular analysis.

Animals↗
PubMed2003

Chemical processing on microchips for analysis, synthesis, and bioassay.

This review describes our recent research on miniaturization of chemical systems. We have developed a miniaturization methodology based on pressure-driven multiphase laminar flow and a highly sensitive detection tool, the thermal lens microscope. Some representative applications of the methodology in the fields of analysis, synthesis, and bioassay are described.

Microscopy↗
PubMed2003

An interface chip connection between capillary electrophoresis and thermal lens microscope.

A thermal lens microscope (TLM) detection of capillary electrophoresis (CE) utilizing microchip technology was developed. Fused-silica capillaries with an inner diameter of 50 microm were directly connected to a microchannel in a microchip. The detection limit by TLM was estimated as 2.8 x 10(-7) absorbance by measuring pure water. The detection limit of derivatized amino acids determined by CE-TLM was estimated as 2.4 x 10(-8) M, which was 100 times lower than that of conventional absorbance detection.

Amino Acids↗
PubMed2003

Integration of chemical and biochemical analysis systems into a glass microchip.

This review focuses on the integration of chemical and biochemical analysis systems into glass microchips for general use. By combining multiphase laminar flow driven by pressure and micro unit operations, such as mixing, reaction, extraction and separation, continuous-flow chemical processing systems can be realized in the microchip format, while the application of electrophoresis-based chip technology is limited. The performances of several analysis systems were greatly improved by microchip integration because of some characteristics of microspace, i.e., a large specific interface area, a short molecular diffusion time, a small heat capacity and so on. By applying these concepts, several different analysis systems, i.e., wet analysis of cobalt ion, multi-ion sensor, immunoassay, and cellular analysis, were successfully integrated on a microchip. These microchip technologies are promising for meeting the future demands of high-throughput chemical processing.

Biosensing Techniques↗
PubMed2002

Conversion of gastric mucosa to intestinal metaplasia in Cdx2-expressing transgenic mice.

Gastric intestinal metaplasia occurs as a pathological condition in the gastric mucosa. To clarify how an intestine-specific homeobox gene, Cdx2, affects the morphogenesis of gastric mucosa, we generated transgenic mice expressing Cdx2 in parietal cells. Until Day 18 after birth, the number of parietal cells inthegastric mucosa of transgenic mice was the same as for their normal littermates. However, at Day 19, we detected several glands in which parietal cells disappeared and the proliferating zone moved from the isthmus to the base of the glands. Thereafter, parietal cells decreased gradually and disappeared at Day 37. All of the gastric mucosal cells, except for enterochromaffin-like (ECL) cells, were completely replaced by intestinal metaplasia, consisting of goblet cells, enteroendocrine cells, and absorptive cells expressing alkaline phosphatase. Pseudopyloric gland metaplasia was also formed. The transgenic mouse is a very useful model for clarifying physiological differentiation of gastric and intestinal cell lineages and analyzing the molecular events from intestinal metaplasia to adenocarcinoma.

Aging↗
PubMed2002

Single-cell analysis by a scanning thermal lens microscope with a microchip: direct monitoring of cytochrome c distribution during apoptosis process.

We developed a microsystem for cell experiments consisting of a scanning thermal lens microscope detection system and a cell culture microchip. The microchip system was good for liquid control in microspace, and this results in secure cell stimulation and coincident in vivo observation of the cell responses. The system could detect nonfluorescent biological substances with extremely high sensitivity without any labeling materials and had a high spatial resolution of approximately 1 microm. This system was applied to monitoring of cytochrome c distribution in a neuroblastoma-glioma hybrid cell cultured in the microflask (1 mm x 10 mm x 0.1 mm; 1 microL) fabricated in a glass microchip. Cytochrome c release from mitochondria to cytosol during the apoptosis process was successfully monitored with this system. The cytochrome c detected with this system was estimated to be approximately 10 zmol. We concluded that the system was suitable for measuring the distribution of chemical substances in a single cell because the microchip is good for liquid handling in microspace and the thermal lens microscope has high sensitivity and spatial resolution.

Apoptosis↗
PubMed2002

Continuous-flow chemical processing on a microchip by combining microunit operations and a multiphase flow network.

A new design and construction methodology for integration of complicated chemical processing on a microchip was proposed. This methodology, continuous-flow chemical processing (CFCP), is based on a combination of microunit operations (MUOs) and a multiphase flow network. Chemical operations in microchannels, such as mixing, reaction, and extraction, were classified into several MUOs. The complete procedure for Co(II) wet analysis, including a chelating reaction, solvent extraction, and purification was decomposed into MUOs and reconstructed as CFCP on a microchip. Chemical reaction and molecular transport were realized in and between continuous liquid flows in a multiphase flow network, such as aqueous/aqueous, aqueous/organic, and aqueous/organic/aqueous flows. When the determination of Co(II) in an admixture of Cu(II) was carried out using this methodology, the determination limit (2sigma) was obtained as 18 nM, and the absolute amount of Co chelates detected was 0.13 zmol, that is, 78 chelates. The sample analysis time was faster than that of a conventional processing system. Moreover, troublesome operations such as phase separation and acid and alkali washing, all necessary for the conventional system, were simplified. The CFCP methodology proposed here can be applied to various on-chip applications.

Journal Article↗
PubMed2002

Microchip-based immunoassay system with branching multichannels for simultaneous determination of interferon-gamma.

A bead-bed immunoassay system suitable for simultaneous assay of multiple samples was constructed on a microchip. The chip had branching multichannels and four reaction and detection regions; the constructed system could process four samples at a time with only one pump unit. Interferon gamma was assayed by a 3-step sandwich immunoassay with the system coupled to a thermal lens microscope as a detector. The biases of the signal intensities obtained from each channel were within 10%, and coefficients of variation were almost the same level as the single straight channel assay. The assay time for four samples was 50 min instead of 35 min for one sample in the single-channel assay; hence higher throughput was realized with the branching structure chip.

Animals↗
PubMed2002

[Guidelines in the management of gastric ulcer with special reference to elderly patients].

Special care must be taken for peptic ulcer disease in the elderly because of more frequent complications such as major bleeding that require hospitalization and may sometimes result in fatal outcome. In addition, elderly patients are more vulnerable to such complications due to accompanying systemic diseases such as cardiovascular, pulmonary or liver diseases. Therefore, it is important to prevent ulcer complications for the high-risk group in the elderly. For the prevention and treatment of ulcer disease in elderly patients, medication with fewer drug-interactions given in simple dose schedule is preferable for better compliance as well as for reducing side effects. Furthermore, consideration on cost-effectiveness of the treatment is increasingly important because of severe burden on the health insurance system. In an attempt to give better and more efficient management strategy for gastric ulcer, evidence-based clinical guideline is being prepared under the support of Japanese Ministry of Health and Welfare. Rational management of ulcer disease in the elderly, however, requires deliberate consideration of each patient status and stringent, inflexible application of the guideline should be avoided.

Aged↗