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K Kose

Publications and source records attributed to K Kose.

17 recordsLinked to original sources
PubMed2001

Development of a 1.0 T MR microscope using a Nd-Fe-B permanent magnet.

A compact 1.0 T MR microscope was developed using a permanent magnet made of high performance Nd-Fe-B magnetic material and a compact MRI console (54 cm (W) x 77 cm (H) x 60 cm (D), 80 kg weight). Since the magnetic field of the permanent magnet had a large temperature coefficient (-1200 ppm/deg), an internal NMR locking technique was developed for the imaging sequences. The performance of the system was evaluated using several biological specimens. As a result, good SNR 3D images at (50 microm)(3)-(200 microm)(3) voxel dimensions were obtained in practical imaging times (0.5-7.5 hours). Thus we have concluded that the permanent-magnet compact MR microscope has great promise as a research or analytical tool.

Animals↗
PubMed2001

Architecture of baked breads depicted by a magnetic resonance imaging.

The architecture of baked breads made of fresh dough and frozen dough was depicted by magnetic resonance imaging (MRI). Pieces of bread (16 mm cubic cakes) were soaked in organic solvents containing various concentrations of heavy metals (Cu(2+), Co(2+) and Fe(3+)) and images of the grain structure of the breads were obtained. Of the organic solvents tested, acetone was preferable because of its single peak that prevents chemical shift effects on images, the retention of the bread structure, and the solubility of heavy metals. The heavy metals, especially Fe(3+), shortened the overly long relaxation times of acetone to practical lengths for imaging and stained the materials to provide high contrasts. The images obtained in acetone with 8 mM Fe(3+) were suitable for analyzing crumb grain structures. The bread of fresh dough showed a uniform distribution of pores of various sizes made of thin gluten sheets, whereas the pores in the bread of frozen dough were less, prominently large, non-uniformly distributed, and made of thick gluten sheets.

Bread↗
PubMed1999

[Application of a new MR microscope using an independent console system (MRMICS) for biological tissues in vitro].

We studied microscopic MR images of the normal appendix in vitro using a new MR microscope system: MR Microscope using an Independent Console System (MRMICS). The MRMICS was placed in the clinical MR room, and the probe box was fixed on the bed of the 1.5 T clinical MR machine. T1-, T2-, and proton density-weighted images were obtained using spin echo sequences with an in-plane pixel size of 100 x 100 microns. Zonal structures of the appendix were clearly demonstrated with different contrast by different sequences. Therefore, the MRMICS is a useful add-on system for investigating microscopic MR images of biological tissues in vitro.

Appendix↗
PubMed1998

Real-time image reconstruction and display system for MRI using a high-speed personal computer.

A real-time NMR image reconstruction and display system was developed using a high-speed personal computer and optimized for the 32-bit multitasking Microsoft Windows 95 operating system. The system was operated at various CPU clock frequencies by changing the motherboard clock frequency and the processor/bus frequency ratio. When the Pentium CPU was used at the 200 MHz clock frequency, the reconstruction time for one 128 x 128 pixel image was 48 ms and that for the image display on the enlarged 256 x 256 pixel window was about 8 ms. NMR imaging experiments were performed with three fast imaging sequences (FLASH, multishot EPI, and one-shot EPI) to demonstrate the ability of the real-time system. It was concluded that in most cases, high-speed PC would be the best choice for the image reconstruction and display system for real-time MRI.

Equipment Design↗
PubMed1997

A method to extract three-dimensional objects from three-dimensional NMR image data.

A method to extract shapes of bubble polyhedra from three-dimensional nuclear magnetic resonance image data of foam has been developed. The method consists of four steps: first, to compute series of maximum intensity projection images from the three-dimensional NMR image data of foam to visualize the network structure of the bubble edges; second, to measure the three-dimensional coordinates of vertices of the bubble polyhedra interactively on a CRT using the series of MIP images to obtain polyhedral edges; third, to construct polyhedral faces from the assembly of the edge data; and fourth, to construct bubble polyhedra from the assembly of the face data. The algorithm for construction of polygons and polyhedra is based on the selection of polygons or polyhedra from an enormous number of possible combinations of edges or faces under some simple selection rules. Since the computation time for the selection increased exponentially with the number of the edge data, a 'partial volume sweeping' method in which a cubic region which could accommodate any bubble polyhedron was swept over the three-dimensional image area, was developed to reduce the computation time. By using this method, it was demonstrated that the shapes of many bubble polyhedra could be extracted automatically from the assembly of the edge data within a practical computation time.

Image Processing, Computer-Assisted↗
PubMed1997

[Historical developments and present status of rapid NMR imaging].

Rapid NMR imaging methods are historically reviewed and their present status is introduced. Three major rapid imaging techniques, EPI, FLASH, and RARE (Fast SE), are described historically and their typical images are presented. Since some advanced rapid imaging techniques are often harmful to patients, it is suggested that future rapid imaging techniques must be developed to minimize the gradient switching speed and rf power deposition.

Humans↗
PubMed1990

Cloning and nucleotide sequence of the gene braB coding for the sodium-coupled branched-chain amino acid carrier in Pseudomonas aeruginosa PAO.

The gene braB, encoding the Na(+)-coupled carrier for branched-chain amino acids in Pseudomonas aeruginosa PAO, was cloned on cosmid pMMB34. The cosmid clones carrying the braB gene were identified as those that restored growth at low leucine concentration and Na(+)-dependent leucine transport activity to P. aeruginosa PAO3536 defective in the transport of branched-chain amino acids. Determination of the nucleotide sequence of the DNA fragment shows that the braB gene comprises 1311 bp and encodes a hydrophobic protein of 437 amino acids with a calculated Mr of 45,279. The hydropathy profile suggests that there exist in the carrier protein 12 hydrophobic segments long enough to traverse the membrane. The amino acid sequence shows a high degree of homology with the brnQ product, a branched-chain amino acid carrier of Salmonella typhimurium, while no homology in the nucleotide sequences is found in the braB and brnQ genes.

Amino Acid Sequence↗
PubMed1990

Cloning, nucleotide sequences, and identification of products of the Pseudomonas aeruginosa PAO bra genes, which encode the high-affinity branched-chain amino acid transport system.

A DNA fragment of Pseudomonas aeruginosa PAO containing genes specifying the high-affinity branched-chain amino acid transport system (LIV-I) was isolated. The fragment contained the braC gene, encoding the binding protein for branched-chain amino acids, and the 4-kilobase DNA segment adjacent to 3' of braC. The nucleotide sequence of the 4-kilobase DNA fragment was determined and found to contain four open reading frames, designated braD, braE, braF, and braG. The braD and braE genes specify very hydrophobic proteins of 307 and 417 amino acid residues, respectively. The braD gene product showed extensive homology (67% identical) to the livH gene product, a component required for the Escherichia coli high-affinity branched-chain amino acid transport systems. The braF and braG genes encode proteins of 255 and 233 amino acids, respectively, both containing amino acid sequences typical of proteins with ATP-binding sites. By using a T7 RNA polymerase/promoter system together with plasmids having various deletions in the braDEFG region, the braD, braE, braF, and braG gene products were identified as proteins with apparent Mrs of 25,500, 34,000, 30,000, and 27,000, respectively. These proteins were found among cell membrane proteins on a sodium dodecyl sulfate-polyacrylamide gel stained with Coomassie blue.

Amino Acid Sequence↗
PubMed1990

Genetic analysis of the Pseudomonas aeruginosa PAO high-affinity branched-chain amino acid transport system by use of plasmids carrying the bra genes.

About 30 mutants of Pseudomonas aeruginosa PAO defective in the high-affinity branched-chain amino acid transport system (LIV-I) were isolated by the selection for resistance to 4-aza-DL-leucine, a toxic leucine analog for LIV-I. All of the mutants were complemented by plasmid pKTH24, harboring the braC gene, which encodes the branched-chain amino acid-binding protein, and the four open reading frames named braD, braE, braF, and braG (T. Hoshino and K. Kose, J. Bacteriol. 172:5531-5539, 1990). We identified five cistrons corresponding to these bra genes by complementation analysis with various derivatives of pKTH24, confirming that the braD, braE, braF, and braG genes are required for the LIV-I transport system. We also found mutations that seem likely to be mutations in a promoter region for the bra genes and those with polarity in the intercistronic region between braC and braD. Analysis with an omega interposon showed that the bra genes are organized as an operon and are cotranscribed in the order braC-braD-braE-braF-braG from a promoter located in the 5'-flanking region of the braC gene.

Alleles↗
PubMed1989

Image reconstruction algorithm for single-photon-emission computed tomography with uniform attenuation.

A new method is presented for obtaining an analytical solution to the image-reconstruction problem in single-photon-emission computed tomography. The rigorous solution is introduced by applying an analytical continuation process to the two-dimensional Fourier transform of the image, which is derived from the one-dimensional Fourier transforms of projection functions. The calculations can be carried out in a short computation time without involving unstable procedures. Numerical simulations were made to demonstrate the effectiveness of the proposed method.

Algorithms↗
PubMed1989

Cloning and nucleotide sequence of braC, the structural gene for the leucine-, isoleucine-, and valine-binding protein of Pseudomonas aeruginosa PAO.

The gene for the leucine-, isoleucine-, and valine-binding protein (LIVAT-BP) in Pseudomonas aeruginosa PAO was isolated, and its nucleotide sequence was determined. The gene consisted of 1,119 nucleotides specifying a protein of 373 amino acid residues. Determination of the N-terminal amino acid sequence of the LIVAT-BP purified from P. aeruginosa shock fluid suggested that the N-terminal 26 residues of the gene product are cleaved off posttranslationally, showing the characteristic features of procaryotic signal peptides. The amino acid composition of the mature product predicted from the nucleotide sequence was in good agreement with that of the purified LIVAT-BP. The plasmid carrying the LIVAT-BP gene restored the activity of the high-affinity branched-chain amino acid transport system (the leucine, isoleucine, valine [LIV-I] transport system) in the braC310 mutant of P. aeruginosa, confirming that braC is the structural gene for LIVAT-BP. The mutant LIVAT-BP lacking a 16-amino-acid peptide in the middle was found to be functional in the LIV-I transport system. LIVAT-BP showed extensive homology (51% identical) to the LIV- and leucine-specific-binding proteins of Escherichia coli K-12, which are coded for by the livJ and livK genes, respectively, suggesting that the role of the proteins in the LIV-I transport systems is analogous in both organisms.

Amino Acid Sequence↗
PubMedDate not supplied

Experimental results with a whole body NMR-CT scanner using a resistive magnet.

A brief explanation is given on various advantageous features of NMR imaging methods for practical diagnostic purposes. A whole-body NMR-CT scanner utilizing a big resistive air-core magnet has been developed in cooperation with the Institute for Solid State Physics, University of Tokyo. This prototype NMR-CT scanner employs the projection-reconstruction-imaging method with a selective excitation technique for slicing. It can provide physicians with high quality proton NMR images within a practicable, acceptable short data-collection time. Typical NMR-CT images of healthy volunteers and patients were obtained in the experiments using this device, and are presented here. Although the images mainly reflect the hydrogen nucleus concentrations of the subjects, they are strongly affected by relaxation times T1 and T2 and also by the the subjects' internal and external bodily activities. The effects of various NMR parameters in the reconstructed images are analyzed and examples showing these parameter effects are demonstrated. Another advantage of NMR imaging shown here, is a sagittal image of a human body, which is difficult to obtain by using an X-ray CT scanner.

Abdomen↗