Masao Kamahori

Bio: Masao Kamahori is an academic researcher from Hitachi. The author has contributed to research in topics: Reference electrode & Electrode. The author has an hindex of 22, co-authored 123 publications receiving 2124 citations. Previous affiliations of Masao Kamahori include Ritsumeikan University & National Institute for Materials Science.

DNA Analysis Chip Based on Field-Effect Transistors

Abstract: We have been developing a genetic field-effect transistor (FET) based on the potentiometric detection of hybridization and intercalation on the Si3N4 gate insulator. In this study, we demonstrated the detection of charge density change as a result of hybridization and intercalation using genetic FETs. Since the electrical output signal is obtained with the genetic FET without any labeling reagent, as compared with the conventional fluorescence-based DNA chips, the genetic FET platform is suitable for a simple and inexpensive system for genetic analysis in clinical diagnostics.

Quantitative detection of single nucleotide polymorphisms for a pooled sample by a bioluminometric assay coupled with modified primer extension reactions (BAMPER)

Abstract: A new method for SNP analysis based on the detection of pyrophosphate (PPi) is demonstrated, which is capable of detecting small allele frequency differences between two DNA pools for genetic association studies other than SNP typing. The method is based on specific primer extension reactions coupled with PPi detection. As the specificity of the primer-directed extension is not enough for quantitative SNP analysis, artificial mismatched bases are introduced into the 3′-terminal regions of the specific primers as a way of improving the switching characteristics of the primer extension reactions. The best position in the primer for such artificial mismatched bases is the third position from the primer 3′-terminus. Contamination with endogenous PPi, which produces a large background signal level in SNP analysis, was removed using PPase to degrade the PPi during the sample preparation process. It is possible to accurately and quantitatively analyze SNPs using a set of primers that correspond to the wild-type and mutant DNA segments. The termini of these primers are at the mutation positions. Various types of SNPs were successfully analyzed. It was possible to very accurately determine SNPs with frequencies as low 0.02. It is very reproducible and the allele frequency difference can be determined. It is accurate enough to detect meaningful genetic differences among pooled DNA samples. The method is sensitive enough to detect 14 amol ssM13 DNA. The proposed method seems very promising in terms of realizing a cost-effective, large-scale human genetic testing system.

Particle handling apparatus for handling particles in fluid by acoustic radiation pressure

Abstract: An ultrasonic manipulation apparatus has a plurality of ultrasonic wave oscillators arranged in two dimensions to trap, fix or move particles to an optional position in the solution or perform cell fusion by using a gradient force obtained by superposing one over another the gradient force fields generated by ultrasonic waves produced by a plurality of ultrasonic wave oscillators. The ultrasonic wave oscillators, functioning independently of one another, can emit ultrasonic waves with optional intensities and phases, and by using an external force produced by superposed gradient force fields generated by ultrasonic waves, particles are handled easily.

Micro-reactor device for minute sample analysis

Abstract: A minute sample analysis system includes a micro-reactor device, a quantitative measuring device, an analyzing device and a controller, whereby, when a very small amount of sample is handled, its dilution and loss can be suppressed to minimum level, and analyzing operations ranging from reaction with a reactive reagent to separation/detection of the sample can be consistently carried out efficiently. The micro-reactor device controls the solution, reactive reagent and sample flowing in the form of electroosmotic flow generated by high-voltage application under control of passage change-over switches. The quantitative measuring device measures the quantity of reactive sample received from the micro-reactor device and introduces the measured reactive sample into the analyzing device. The analyzing device optically detects components separated from the sample through electrophoresis. The above operations are generally controlled under by the controller.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Semiconductor device, and manufacturing method thereof

Abstract: An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Methods and apparatus for measuring analytes using large scale fet arrays

Abstract: An apparatus may include a semiconductor chip and a fluidics assembly. The semiconductor chip has an array of wells and an array of sensors and each sensor of the array of sensors is in fluid communication with a well of the array of wells. The fluidics assembly is located on top of the semiconductor chip and is configured to deliver fluids to the semiconductor chip. The fluidics assembly includes a flow expansion chamber configured to introduce the fluids, an outlet portion configured to pipe out the fluids, and a flow chamber portion. The flow chamber portion is configured to allow the fluids to flow from the flow expansion chamber to the outlet portion and to allow the fluids to interact along the way with material in the array of wells. The flow expansion chamber has a curved wall at the top or bottom so that the height of the flow expansion chamber at the center is less than at the walls that restrict the fluids to the left and right.

Devices and methods for using centripetal acceleration to drive fluid movement in a microfluidics system

Abstract: This invention provides methods and apparatus for performing microanalytic and microsynthetic analyses and procedures. Specifically, the invention provides a microsystem platform for use with a micromanipulation device to manipulate the platform by rotation, thereby utilizing the centripetal force resulting from rotation of the platform to motivate fluid movement through microchannels embedded in the microplatform. The microsystem platforms of the invention are also provided having microfluidics components, resistive heating elements, temperature sensing elements, mixing structures, capillary and sacrificial valves, and methods for using these microsystems platforms for performing biological, enzymatic, immunological and chemical assays. An electronic spindle designed rotor capable of transferring electrical signals to and from the microsystem platforms of the invention is also provided.

Methods and apparatuses for analyzing polynucleotide sequences

Abstract: Methods for high speed, high throughput analysis of polynucleotide sequences, and apparatuses with which to carry out the methods are provided in the invention.