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K Kadowaki

Publications and source records attributed to K Kadowaki.

At least 19 recordsLinked to original sources
PubMed2001

Linear and field-independent relation between vortex core state energy and gap in Bi(2)Sr(2)CaCu(2)O(8+delta).

We present a scanning tunneling spectroscopy study on quasiparticle states in vortex cores in Bi(2)Sr(2)CaCu(2)O(8+delta). The energy of the observed vortex core states shows an approximately linear scaling with the superconducting gap in the region just outside the core. This clearly distinguishes them from conventional localized core states and is a signature of the mechanism responsible for their discrete appearance in high-temperature superconductors. The energy scaling of the vortex core states also suggests a common nature of vortex cores in Bi(2)Sr(2)CaCu(2)O(8+delta) and YBa(2)Cu(3)O(7-delta). Finally, these states do not show any dependence on the applied magnetic field between 1 and 6 T.

Journal Article↗
PubMed2001

Coherent quasiparticle weight and its connection to high-T(c) superconductivity from angle-resolved photoemission.

We study the doping and temperature dependence of the single-particle coherent weight, z(A), for high- T(c) superconductors Bi(2)Sr(2)CaCu(2)O(8+x) using angle-resolved photoemission. We find that at low temperatures the coherent weight z(A) at (pi,0) is proportional to the carrier concentration x and that the temperature dependence of z(A) is similar to that of the c-axis superfluid density. We show that, for a wide range of carrier concentration, the superconducting transition temperature scales with the product of the low-temperature coherent weight and the maximum superconducting gap.

Journal Article↗
PubMed2001

Mitochondrial sequence migrated downstream to a nuclear V-ATPase B gene is transcribed but non-functional.

A promiscuous nuclear sequence containing a mitochondrial DNA fragment was isolated from rice. Nucleotide sequence analysis reveals that the cDNA clone #21 carries a mitochondrial sequence homologous to the 3' portion of the rps19 gene followed by the 5' portion of the rps3 gene. The mitochondrial sequence is present in an antisense orientation. Sequence comparison of the #21 cDNA with the original mitochondrial sequence shows 99% similarity, suggesting a recent transfer event. Moreover, evidence for a lack of an RNA editing event and retaining of the group II intron sequence strongly suggests that the sequence was transferred from mitochondrion to the nucleus via DNA rather than RNA as an intermediate. The upstream region to the mitochondria-derived sequence shows homology to part of the vacuolar H(+)-ATPase B subunit (V-ATPase B) gene. Isolation of a functional V-ATPase B cDNA and its comparison with the #21 cDNA reveal a number of nucleotide substitutions resulting in many translational stop codons in the #21 cDNA. This indicates that the #21 cDNA sequence is not functional. Analysis of genomic sequences shows the presence of five intron sequences in the #21 cDNA, whereas the functional V-ATPase B gene has 14 introns. Of these, three exons and their internal two introns are homologous to each other, suggesting a duplication event of V-ATPase B genomic DNA. The results of this investigation strongly suggest that the mitochondrial sequence was integrated in an antisense orientation into the pre-existing V-ATPase B pseudogene that can be transcribed and spliced. This represents a case of unsuccessful gene transfer from mitochondrion to the nucleus.

Amino Acid Sequence↗
PubMed2001

Renormalization of spectral line shape and dispersion below Tc in Bi2Sr2CaCu2O8+delta.

Angle-resolved photoemission data in the superconducting state of Bi2Sr2CaCu2O8+delta show a kink in the dispersion along the zone diagonal, which is related via a Kramers-Krönig analysis to a drop in the low energy scattering rate. As one moves towards (pi,0), this kink evolves into a spectral dip. The occurrence of these anomalies in the dispersion and line shape throughout the zone indicates the presence of a new energy scale in the superconducting state.

Journal Article↗
PubMed2001

Stepwise behavior of vortex-lattice melting transition in tilted magnetic fields in single crystals of Bi(2)Sr(2)CaCu(2)O(8 + delta).

The vortex-lattice melting transition in Bi(2)Sr(2)CaCu(2)O(8 + delta) single crystals was studied using in-plane resistivity measurements in magnetic fields tilted away from the c axis to the ab plane. In order to avoid the surface barrier effect which hinders the melting transition in the conventional transport measurements, we used the Corbino geometry of electric contacts. The complete H(c) - H(ab) phase diagram of the melting transition in Bi(2)Sr(2)CaCu(2)O(8 + delta) is obtained for the first time. The c-axis melting field component H(c)(melt) exhibits the novel, stepwise dependence on the in-plane magnetic fields H(ab) which is discussed on the basis of the crossing vortex-lattice structure. The peculiar resistance behavior observed near the ab plane suggests the change of phase transition character from first to second order.

Journal Article↗
PubMed2000

Fermi surface of Bi2Sr2CaCu2O8

We study the Fermi surface of Bi2Sr2CaCu2O8 using angle resolved photoemission spectroscopy (ARPES) with a momentum resolution of approximately 0.01 of the Brillouin zone. We show that, contrary to recent suggestions, the ARPES derived Fermi surface is a large hole barrel centered at (pi,pi), independent of the incident photon energy. We caution that the photon energy and k dependence of the matrix elements, if not properly accounted for, can lead to misinterpretation of ARPES intensities.

Journal Article↗
PubMed2000

Quasiparticles in the superconducting state of Bi(2)Sr(2)CaCu(2)O(8+delta)

Recent improvements in momentum resolution lead to qualitatively new angle-resolved photoemission spectroscopy results on the spectra of Bi(2)Sr(2)CaCu(2)O(8+delta) (Bi2212) along the (pi,pi) direction, where there is a node in the superconducting gap. We now see the intrinsic line shape, which indicates the presence of true quasiparticles at all Fermi momenta in the superconducting state, and lack thereof in the normal state. The region of momentum space probed here is relevant for charge transport, motivating a comparison of our results to conductivity measurements by infrared reflectivity.

Journal Article↗
PubMed2000

Asymmetric Synthesis of an Organic Compound with High Enantiomeric Excess Induced by Inorganic Ionic Sodium Chlorate This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports, and Culture. We thank Mr. Koji Ohtake for experimental work in the early stage, Prof. Naoyuki Koide and Dr. Takashi Mihara from the Department of Chemistry of our university for a microscope measurement of the size of the powdered NaClO(3).

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Journal Article↗
PubMed2000

Transfer of the mitochondrial rps10 gene to the nucleus in rice: acquisition of the 5' untranslated region followed by gene duplication.

Mitochondrial ribosomal protein S10 (rps10) is encoded by the mitochondrial genome in potato and pea. Here we show that the rps10 gene is absent from the mitochondrial genome of rice and has been transferred to the nucleus. Cloning and transcriptional analysis show that there are two rps10 genes in the rice nuclear genome and that their transcripts differ in abundance. Western analysis detected the RPS10 protein in the soluble fraction of rice mitochondria, although neither RPS10 has any obvious N-terminal presequence for targeting to mitochondria. This result suggests that targeting information is present in the internal region of rice RPS10. Genomic sequence analysis indicated that each rps10 gene has an intron in the 5' untranslated region (5' UTR) and that these intron sequences are homologous to each other. This result strongly suggests that a duplication event occurred after transfer of the rps10 gene to the nucleus. The duplicated rps10 genes have since been translocated to different chromosomes, because the two rps10 genes were mapped on chromosomes 6 and 12 by RFLP analysis. Interestingly, the 5' UTR and the intron of the rice rps10 genes are homologous to sequences found in several rice genes with various functions, such as osk4, EF-1beta2 and RAG1, suggesting a common origin and a functional role for the 5' UTR. Acquisition of the 5' flanking region might have accelerated the activation of the mitochondrial rps10 gene which was transferred to the nuclear genome.

5' Untranslated Regions↗
PubMed1999

A single nuclear transcript encoding mitochondrial RPS14 and SDHB of rice is processed by alternative splicing: common use of the same mitochondrial targeting signal for different proteins.

The rice mitochondrial genome has a sequence homologous to the gene for ribosomal protein S14 (rps14), but the coding sequence is interrupted by internal stop codons. A functional rps14 gene was isolated from the rice nuclear genome, suggesting a gene-transfer event from the mitochondrion to the nucleus. The nuclear rps14 gene encodes a long N-terminal extension showing significant similarity to a part of mitochondrial succinate dehydrogenase subunit B (SDHB) protein from human and a malarial parasite (Plasmodium falciparum). Isolation of a functional rice sdhB cDNA and subsequent sequence comparison to the nuclear rps14 indicate that the 5' portions of the two cDNAs are identical. The sdhB genomic sequence shows that the SDHB-coding region is divided into two exons. Surprisingly, the RPS14-coding region is located between the two exons. DNA gel blot analysis indicates that both sdhB and rps14 are present at a single locus in the rice nucleus. These findings strongly suggest that the two gene transcripts result from a single mRNA precursor by alternative splicing. Protein blot analysis shows that the size of the mature RPS14 is 16.5 kDa, suggesting removal of the N-terminal 22.6-kDa peptide region. Considering that the rice mitochondrial genome lacks the sdhB gene but contains the rps14-related sequence, transfer of the sdhB gene seems to have occurred before the transfer of the rps14 gene. The migration of the mitochondrial rps14 sequence into the already existing sdhB gene could bestow the capacity for nuclear expression and mitochondrial targeting.

Alternative Splicing↗
PubMed1999

Identification of cDNA encoding cytochrome c oxidase subunit 5c (COX5c) from rice: comparison of its expression with nuclear-encoded and mitochondrial-encoded COX genes.

Little is presently known about the nuclear-encoded genes for cytochrome c oxidase (COX) in higher plants. In rice, only the nuclear-encoded COX5b gene has been reported. To understand the relationship between the expression of nuclear-encoded and mitochondrial-encoded COX genes in rice, we first characterized a cDNA encoding one of the other nuclear COX genes, COX5c, which encodes 63 amino acids. The deduced amino acid sequence of COX5c from rice was highly homologous to that from sweet potato. Genomic Southern hybridization indicated that the rice COX5c subunit is encoded by a single copy of the COX5c gene. Furthermore, we compared the expression patterns of the nuclear-encoded COX5c and COX5b genes with the expression pattern of the mitochondrial-encoded COX1 gene among several organs by Northern blot analysis. The results suggested that regulatory systems of expression between the nuclear-encoded and the mitochondrial-encoded COX genes are different among different organs in rice.

Amino Acid Sequence↗
PubMed1999

[Elevation of serum and urine tumor necrosis factor levels after transurethral resection of the prostate].

BACKGROUND: Recent studies have suggested that inflammatory cytokines are major mediator of the acute phase protein response after surgery. The aim of the present study is to investigate the relationship between the degree of surgical trauma and the change of serum and urine cytokine levels after transurethral resection of the prostate (TUR-P). METHOD: Serum and urine concentrations of tumor necrosis factor-alpha (TNF), interleukin-6 (IL 6), and interleukin-1 (IL 1) were evaluated in 55 patients who underwent TUR-P and in 23 patients who underwent abdominal surgery. The samples were collected periodically before and after an intervention, and the concentrations of cytokines were measured by enzyme-linked immunosorbent assay. RESULTS: The concentration of serum TNF was significantly increased 6 hours after TUR-P. Since serum TNF level was not increased after abdominal surgery, serum TNF level was significantly higher after TUR-P than after abdominal surgery. Serum IL 6 and IL 1 levels were not increased after TUR-P. Urine levels of TNF, IL 6 and IL 1 were significantly increased after TUR-P, meanwhile no significant elevation of urine cytokine levels was recognized in the patients who underwent abdominal surgery. The elevation of urine cytokine levels was thought to be caused by the increased production of cytokines at the surgically resected sites. The urine TNF level after TUR-P was increased related to the resected tissue volume and irrigation fluid volume. The preoperative urinary tract infection caused excessive elevation of the urine TNF level after TUR-P. The urine TNF level after TUR-P also tended to be increased depending on the degree of postoperative pyrexia. CONCLUSION: These results indicate the unique response of TNF to TUR-P. Measurement of serum and urine TNF levels after TUR-P can be a useful index for evaluating the perioperative condition of the patients undergoing TUR-P.

Adult↗
PubMed1999

[A case of pelvic aggressive angiomyxoma involving urinary bladder].

A 23-year-old man visited hospital with the complaints of hematuria and miction pain. Computed tomography and magnetic resonance imaging of the pelvis showed a large pelvic tumor contiguous to the urinary bladder. Resection of the tumor with partial cystectomy was performed on February, 1998. Histopathological examination showed that the tumor composed of angiomyxoma infiltrating into the urinary bladder. The patient is alive without recurrence of aggressive angiomyxoma 12 months after surgery. To our knowledge, this is the first report in the Japanese literature of aggressive angiomyxoma involving the urinary bladder. Awareness of this uncommon neoplasma is important in the diagnosis of pelvic tumor to prevent an extensive surgery.

Adult↗
PubMed1998

Genes for the ribosomal S4 protein encoded in higher plant mitochondria are transcribed, edited, and translated.

Here we describe the structure and expression of the mitochondrial gene that encodes the S4 subunit of the mitochondrial ribosome (rps4) in two higher plants, rapeseed and rice. The ORFs of rapeseed and rice rps4 genes are 362 and 352 codons long, respectively, and their corresponding transcripts are edited (C-to-U conversions) in 19 and 15 positions, respectively. The amino acid sequences deduced from the sequences of the two rps4 genes are 78.1% identical to each other and show about 50% identity to the liverwort (Marchantia polymorpha) mitochondrial RPS4 polypeptide. Both higher plant mitochondrial genes have an inserted sequence (of 137 and 141 codons for rapeseed and rice, respectively) relative to the liverwort rps4 gene. In rice rps4, the 3' portion of the inserted sequence can potentially form two stem-loop structures that resemble two domains characteristic of group II introns, i.e., domains V and VI. However, RT-PCR analysis showed that these sequences were not spliced out during maturation of the rps4 transcripts. Antibodies specific for the plant RPS4 proteins were prepared. Protein blot analysis revealed that RPS4 polypeptides are present in both rapeseed and rice mitochondria, whose sizes are in agreement with the molecular weights calculated from the non-spliced sequences. The rps4 genes and RPS4 polypeptides have been also identified in the mitochondria of wheat, maize, soybean, and turnip by Southern and Western analyses, respectively.

Amino Acid Sequence↗
PubMed1998

Sensitivity in detection of hypervascular hepatocellular carcinoma by helical CT with intra-arterial injection of contrast medium, and by helical CT and MR imaging with intravenous injection of contrast medium.

PURPOSE: To determine the effectiveness of i.a. contrast-enhanced helical CT and of i.v. contrast-enhanced helical CT and MR imaging, in detecting hypervascular hepatocellular carcinoma (HCC). MATERIAL AND METHODS: Fifty patients with 125 hypervascular HCC nodules underwent helical CT both during arterial portography (CTAP) and during hepatic arteriography (CTHA). Helical CT and MR imaging of the entire liver with i.v. administration of contrast medium were also performed. Helical CT images were obtained at 30-33 s (arterial-phase CT) and at 5 min (equilibrium-phase CT) after the initiation of an i.v. bolus injection of contrast medium. After T1- and T2-weighted spin-echo MR imaging, gradient-echo images during breath-holding were obtained prior to and 20 s, 1 min, and 2 min after the bolus administration of 0.1 mmol/kg of gadopentetate dimeglumine (dynamic MR). The sensitivity and positive predictive value of the various techniques were evaluated and compared. RESULTS: In terms of sensitivity for hypervascular HCC nodules of less than 1 cm in diameter, CTAP (90%) and CTHA (88%) were significantly superior to dynamic MR imaging (44%), arterial-phase CT (39%), spin-echo MR imaging (20%), and equilibrium-phase CT (7%) (p < 0.001). However, there was no significant difference in the techniques with regard to the detection of lesions equal to or more than 2 cm in diameter. CONCLUSION: For detecting small hypervascular HCCs, helical CT with i.a. contrast enhancement is superior to helical CT and MR imaging with i.v. enhancement.

Adult↗
PubMed1998

Cloning of genes encoding auxin-binding proteins (ABP19/20) from peach: significant peptide sequence similarity with germin-like proteins.

An auxin-binding protein (ABP) was previously isolated from shoot apices of peach trees to homogenity on standard SDS-PAGE. Analysis of low-bis SDS-PAGE and direct peptide sequencing of purified peach ABP demonstrated that the ABP was composed of two types of polypeptides (designated ABP19 and ABP20). Several cDNA and genomic clones which encode peach ABPs were obtained and analysed. We found that there are at least three classes of ABPs in the peach genome. Open reading frames of these ABPs were 627 bp, predicting a 209 amino acid polypeptide of 22 kDa. An N-terminal hydrophobic signal sequence of 18 amino acids and a putative N-glycosylation site at N60-T-T/S were deduced. Homology search analysis revealed that ABP19 is highly homologous to proteins related to the germin family. The deduced amino acid sequence of ABP19 showed very low overall sequence homology with ABP1, an ABP isolated from maize coleoptile, but it contained a small region which shared 40% homology with a putative auxin binding site in ABP1 (BoxA). In addition, the sequence surrounding the region is highly conserved among peach ABPs and the germin family.

Amino Acid Sequence↗
PubMed1998

[Evaluation of the E-test: comparison of E-test and microbroth dilution method in azole antifungal susceptibility test].

The susceptibilities of clinical isolates of Candida spp. to fluconazole (FLCZ), itraconazole (ITCZ) and ketoconazole (KCZ) were determined by a new method, E-test (AB BIODISK, Sweden) and compared with those obtained by the microbroth dilution method. The MIC values of the 3 azoles obtained by the two methods were, in general, in good agreement. While MICs of FLCZ and KCZ demonstrated higher essential agreement rates and better correlation by both methods, MIC values of ITCZ by the E-test had a tendency to be higher than those of the microbroth dilution method in azole resistant strains. Potential usability of E-test as a broth dilution method for susceptibility tests for clinically isolated Candida spp. including azole resistant strains was discussed.

Antifungal Agents↗