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Biomedical subjects

K Harada

Publications and source records attributed to K Harada.

At least 55 records · Page 3Linked to original sources
PubMed2002

Observation of structures of chain vortices inside anisotropic high- Tc superconductors.

In order to elucidate the formation mechanism of unconventional arrangements of vortices in high- Tc superconducting thin films at an inclined magnetic field to the layer plane, we investigated the structures of vortex lines inside the films by Lorentz microscopy using our 1-MV field-emission electron microscope. Our observation results concluded that vortex lines are tilted to form linear chains in YBaCu3O(7,8). Vortex lines in the chain-lattice state in Bi2Sr2CaCu2O(8+delta), on the other hand, are all perpendicular to the layer plane, and therefore only vortices lined up along Josephson vortices form chains.

Journal Article↗
PubMed2002

Ca(2+)-desensitizing effect of a deletion mutation Delta K210 in cardiac troponin T that causes familial dilated cardiomyopathy.

A deletion mutation Delta K210 in cardiac troponin T (cTnT) was recently found to cause familial dilated cardiomyopathy (DCM). To explore the effect of this mutation on cardiac muscle contraction under physiological conditions, we determined the Ca(2+)-activated force generation in permeabilized rabbit cardiac muscle fibers into which the mutant and wild-type cTnTs were incorporated by using our TnT exchange technique. The free Ca(2+) concentrations required for the force generation were higher in the mutant cTnT-exchanged fibers than in the wild-type cTnT-exchanged ones, with no statistically significant differences in maximal force-generating capability and cooperativity. Exchanging the mutant cTnT into isolated cardiac myofibrils also increased the free Ca(2+) concentrations required for the activation of ATPase. In contrast, a deletion mutation Delta E160 in cTnT that causes familial hypertrophic cardiomyopathy (HCM) decreased the free Ca(2+) concentrations required for force generation, just as in the case of the other HCM-causing mutations in cTnT. The results indicate that cTnT mutations found in the two distinct forms of cardiomyopathy (i.e., HCM and DCM) change the Ca(2+) sensitivity of cardiac muscle contraction in opposite directions. The present study strongly suggests that Ca(2+) desensitization of force generation in sarcomere is a primary mechanism for the pathogenesis of DCM associated with the deletion mutation Delta K210 in cTnT.

Adenosine Triphosphatases↗
PubMed2002

Non-mutated tumor-rejection antigen peptides elicit type-I allergy in the majority of healthy individuals.

IgE-mediated type-I allergy is generally considered to be a hypersensitivity reaction to foreign antigens, and it is believed that self-antigens do not evoke this type of allergy. We report here, for the first time, that non-mutated self-antigen peptides identified as tumor-rejection antigen peptides recognized by HLA class I-restricted and tumor-specific cytotoxic T lymphocytes (CTLs) elicited a type-I allergy in the majority of healthy individuals. Peptide-specific IgE was detectable in sera from certain cases, although the levels did not always correlate with those of type-I allergy. Repeated vaccinations of nonallergic peptides derived from the same antigens possessing allergic peptides resulted in the suppression of both allergic peptide-specific IgE responses and type-I allergy, providing evidence for a new approach to the development of peptide-based desensitization.

Adult↗
PubMed2002

Phylogeographical structure revealed by chloroplast DNA variation in Japanese beech (Fagus crenata Blume).

Intraspecific genetic variation in three non-coding chloroplast DNA (cpDNA) regions (trnT-L and trnL-F spacers, and trnL intron) of Japanese beech (Fagus crenata Blume) was investigated. This species is a major constituent of the typical cool-temperate deciduous forests in Japan. Twenty-one F. crenata populations from throughout Japan, and four F. japonica populations, a close relative of F. crenata, were examined. Seven haplotypes were distinguishable in F. crenata based on nucleotide substitutions and indels. Pairwise nucleotide diversities among haplotypes ranged from 0.0000 to 0.0042 for F. crenata, including F. japonica. The geographical distribution of cpDNA haplotypes was found to be highly structured in F. crenata. Four haplotypes predominated: haplotypes FC1 and FC4 are prevalent on the Pacific Ocean coast, haplotype FC6 is prevalent on the Japan sea coast from the San-in district to Hokkaido, whilst haplotype FC3 is restricted to northern Kyushu and the western-most part of Honshu. Two haplotypes (FC5 and FC7) are restricted to single populations and one haplotype (FC2) is a derivative of FC1. Each of these haplotypes, except FC2, are thought to be derived from different glacial refugia. Phylogenetic analysis showed that neither F. crenata nor F. japonica was monophyletic for the haplotypes, suggesting either ancestral polymorphism or ancient introgression between the lineages of these two Fagus species.

DNA, Chloroplast↗
PubMed2002

Non-invasive measurement of coronary flow reserve in children with Kawasaki disease.

OBJECTIVE: To investigate whether transthoracic Doppler echocardiography (TTE) can reliably measure the coronary flow reserve in the left anterior descending coronary artery in children with Kawasaki disease. DESIGN: Coronary flow velocity in the distal left anterior descending coronary artery was measured by TTE and was compared with that obtained by intracoronary Doppler guide wire. The ratio of maximum hyperaemia (intravenous administration of adenosine triphosphate, 160 microg/kg/min) to baseline peak (mean) diastolic coronary flow velocity in the distal artery was used as an estimate of coronary flow reserve. SETTING: University hospital. PATIENTS: 10 patients with significant left anterior descending coronary stenosis (> 70% diameter stenosis) (group A) in the proximal or middle portion of the artery and 14 patients (group B) without significant stenosis, all with Kawasaki disease documented by previous coronary angiography. RESULTS: The reduced hyperaemic coronary flow velocity in group A compared with group B resulted in a markedly lower coronary flow reserve, derived from both peak diastolic velocity and mean diastolic velocity by either technique of investigation. Multivariate analysis identified the best predictor of left anterior descending coronary artery stenosis to be a coronary flow reserve of < or = 2.2, derived from mean diastolic flow velocity measured using TTE (sensitivity 90%, specificity 100%, accuracy 96%). A good correlation was found between diastolic velocity derived values for coronary flow reserve measured using both TTE and Doppler guide wire (r = 0.92, p = 0.0001). CONCLUSIONS: Coronary flow reserve in the distal left anterior descending coronary artery can be accurately measured using TTE without any intravascular instrumentation in children with Kawasaki disease.

Adolescent↗
PubMed2001

Construction of a genetic linkage map of the model legume Lotus japonicus using an intraspecific F2 population.

Among leguminous plants, the model legume Lotus japonicus (Regel) Larsen has many biological and genetic advantages. We have developed a genetic linkage map of L. japonicus based on amplified fragment length polymorphism (AFLP), simple sequence repeat polymorphism (SSRP) and derived cleaved amplified polymorphic sequence (dCAPS). The F2 mapping population used was derived from a cross between two L. japonicus accessions Gifu B-129 and Miyakojima MG-20. These parental accessions showed remarkable cytological differences, particularly with respect to size and morphology of chromosomes 1 and 2. Using fluorescence in situ hybridization (FISH) with BAC clones from Gifu B-129 and TAC (Transformation-competent Artificial Chromosome) clones from Miyakojima MG-20, a reciprocal translocation was found to be responsible for the cytological differences between chromosomes 1 and 2. The borders of the translocations were identified by FISH and by alignment toward the L. filicaulis x L. japonicus Gifu B-129 linkage map. The markers from the main translocated region were located on linkage groups 1 and 2 of the two accessions, Gifu B-129 and Miyakojima MG-20, respectively. The framework of the linkage map was constructed based on codominant markers, and then dominant markers were integrated separately in each linkage group of the parents. The resulting linkage groups correspond to the six pairs of chromosomes of L. japonicus and consist of 287 markers with 487.3 cM length in Gifu B-129 and 277 markers with 481.6 cM length in Miyakojima MG-20. The map and marker information is available through the World Wide Web at http://www.kazusa.or.jp/lotus/.

Chromosome Mapping↗
PubMed2001

Aberrant promoter methylation profile of bladder cancer and its relationship to clinicopathological features.

We investigated the aberrant promoter methylation profile of bladder cancers and correlated the data with clinicopathological findings. The methylation status of 10 genes was determined in 98 surgically resected bladder cancers, and we calculated the median methylation index (MI), a reflection of the methylated fraction of the genes tested. Methylation frequencies of the genes tested in bladder cancers were 36% for CDH1, 35% for RASSF1A and APC, 29% for CDH13, 16% for FHIT, 15% for RAR beta, 11% for GSTP1, 7% for p16(INK4A), 4% for DAPK, and 2% for MGMT. Methylation of four of the individual genes (CDH1, RASSF1A, APC, and CDH13) and the MI were significantly correlated with several parameters of poor prognosis (tumor grade, growth pattern, muscle invasion, tumor stage, and ploidy pattern). Methylation of CDH1, FHIT, and a high MI were associated with shortened survival. CDH1 methylation positive status was independently associated with poor survival in multivariate analyses. Our results suggest that the methylation profile may be a potential new biomarker of risk prediction in bladder cancer.

Adult↗
PubMed2001

Oscillating rows of vortices in superconductors.

Superconductors can be used as dissipation-free electrical conductors as long as vortices are pinned. Vortices in high-temperature superconductors, however, behave anomalously, reflecting the anisotropic layered structure, and can move readily, thus preventing their practical use. Specifically, in a magnetic field tilted toward the layer plane, a special vortex arrangement (chain-lattice state) is formed. Real-time observation of vortices using high-resolution Lorentz microscopy revealed that the images of chain vortices begin to disappear at a much lower temperature, Td, than the superconducting transition temperature, Tc. We attribute this image disappearance to the longitudinal oscillation of vortices along the chains.

Journal Article↗
PubMed2001

Evaluation of systolic and diastolic ventricular performance of the right ventricle in fetuses with ductal constriction using the Doppler Tei index.

Fetal ductal constriction (DC) can depress right ventricular (RV) function. However, noninvasive assessment of fetal RV function remains difficult. We evaluated RV and left ventricular (LV) performance in fetuses with DC using the Doppler-derived Tei index. The Tei index measures the ratio of total time spent in isovolumic contraction and relaxation (isovolumic time) to the ejection time. Tricuspid inflow and RV outflow Doppler traces for the derivation of RV Tei indexes and mitral inflow and LV outflow traces for LV Tei indexes were measured in 78 fetuses of pregnant women who received indomethacin and 70 normal fetuses (gestational ages ranging from 20 to 39 weeks). DC occurred in 23 fetuses, defined as pulsatility index <1.9. In fetuses with DC, the RV isovolumic time was prolonged and RV ejection time was shortened, and the RV Tei index was high compared with those in fetuses that received indomethacin without DC and normal fetuses. Also, the RV Tei index clearly separated the fetuses with DC from normal and fetuses that received indomethacin without DC (0.74 +/- 0.14 vs 0.35 +/- 0.07 and 0.37 +/- 0.06, respectively; p <0.0001). The LV Tei index was not affected by DC. Serial study in 7 fetuses with DC showed that the RV Tei index decreased from 0.69 +/- 0.12 to 0.38 +/- 0.04 (p = 0.0002) after discontinuation of indomethacin coincident with ductal relaxation, although it remained elevated in 2 cases at the time of ductal relaxation. Thus, the Tei index is a useful and sensitive indicator for detecting abnormal RV performance in fetuses with DC.

Echocardiography, Doppler↗
PubMed2001

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

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.

Base Pair Mismatch↗
PubMed2001

Binding of a SART3 tumor-rejection antigen to a pre-mRNA splicing factor RNPS1: a possible regulation of splicing by a complex formation.

We recently reported the identification of a human SART3 gene that encodes a tumor-rejection antigen recognized by cytotoxic T lymphocytes (CTLs). The squamous-cell carcinoma antigen recognized by T cells-3 (SART3) is an RNA-binding protein expressed in the nucleus of the majority of proliferating cells, including normal cells and malignant cells, but not in normal tissues except for the testes and fetal liver. To determine its biologic function, we employed a 2-hybrid screening in yeast for proteins interacting with SART3, and this method yielded a pre-mRNA splicing factor (RNA-binding protein prevalent during the S phase or RNA-binding protein with a serine-rich domain [RNPS1]) that activated both constitutive and alternative splicing of pre-mRNA in vitro. Interaction of SART3 with RNPS1 through the physical association of N-terminal domains of RNPS1 was confirmed by both in vitro pull-down assay and immunoprecipitation assay. Cotransfection of the 2 genes changed the distribution pattern of SART3 from diffuse nucleoplasmic spreading to nuclear speckled regions in which the RNPS1 was colocalized, suggesting a complex formation of the 2 proteins. In cooperation with RNPS1, SART3 stimulated the proximal alternative 3' splicing of a calcitonin-dihydrofolate reductase chimeric minigene pre-mRNA. These results suggest that SART3 is involved in the regulation of mRNA splicing probably via its complex formation with RNPS1.

Antigens, Neoplasm↗
PubMed2001

Observation of individual vortices trapped along columnar defects in high-temperature superconductors.

Many superconductors do not entirely expel magnetic flux-rather, magnetic flux can penetrate the superconducting state in the form of vortices. Moving vortices create resistance, so they must be 'pinned' to permit dissipationless current flow. This is a particularly important issue for the high-transition-temperature superconductors, in which the vortices move very easily. Irradiation of superconducting samples by heavy ions produces columnar defects, which are considered to be the optimal pinning traps when the orientation of the column coincides with that of the vortex line. Although columnar defect pinning has been investigated using macroscopic techniques, it has hitherto been impossible to resolve individual vortices intersecting with individual defects. Here we achieve the resolution required to image vortex lines and columnar defects in Bi2Sr2CaCu2O8+delta (Bi-2212) thin films, using a 1-MV field-emission electron microscope. For our thin films, we find that the vortex lines at higher temperatures are trapped and oriented along tilted columnar defects, irrespective of the orientation of the applied magnetic field. At lower temperatures, however, vortex penetration always takes place perpendicular to the film plane, suggesting that intrinsic 'background' pinning in the material now dominates.

Journal Article↗
PubMed2001

Synthesis and biological activity of novel macrocyclic antifungals. modification of the tyrosine moiety of the lipopeptidolactone FR901469.

A series of tyrosine-modified derivatives of the macrocyclic lipopeptidolactone FR901469 have been prepared and evaluated for in vitro and in vivo antifungal activity and for hemolytic activity towards red blood cells. Compound 14 displayed significantly reduced hemolytic potential at 1mg/mL and a comparable protective effect to FR901469 in a mouse candidiasis model.

Animals↗
PubMed2001

Severe hypercholesterolemia, hypertriglyceridemia, and atherosclerosis in mice lacking both leptin and the low density lipoprotein receptor.

Leptin-deficient mice (ob/ob) are an excellent murine model for obesity, insulin resistance, and diabetes, all of which are components of a multiple risk factor syndrome that, along with hypercholesterolemia, precipitates a potential high risk for atherosclerosis. In the current study, we show an unexpectedly severe hyperlipidemia in ob/ob mice on a background of low density lipoprotein receptor (LDLR) deficiency (-/-). Doubly mutant mice (LDLR-/-;ob/ob) exhibited striking elevations in both total plasma cholesterol (TC) and triglyceride (TG) levels (1715 +/- 87 and 1016 +/- 172 mg/dl, respectively), at age 3-4 months, resulting in extensive atherosclerotic lesions throughout the aorta by 6 months. Lipoprotein analyses revealed the elevated TC and TG levels to be due to a large increase in an apoB-containing broad-beta remnant lipoprotein fraction. While fasting, diet restriction, and low level leptin treatment significantly lowered TG levels, they caused only slight changes in TC levels. Hepatic cholesterol and triglyceride contents as well as mRNA levels of cholesterologenic and lipogenic enzymes suggest that leptin deficiency increased hepatic triglyceride production but did not change cholesterol production in ob/ob mice regardless of their LDLR genotype. These data provide evidence that the hypertriglyceridemia and hypercholesterolemia in the doubly mutant mice are caused by distinct mechanisms and point to the possibility that leptin might have some impact on plasma cholesterol metabolism, possibly through an LDLR-independent pathway. This model will be an excellent tool for future studies on the relationship between impaired fuel metabolism, increased plasma remnant lipoproteins, diabetes, and atherosclerosis.

Animals↗