Search PubMed⌕ Search

Biomedical subjects

T Takagi

Publications and source records attributed to T Takagi.

At least 163 records · Page 9Linked to original sources
PubMed1999

Measurement of the directional distribution of incident particles in the Shuttle-Mir mission orbit.

The measurement of the directional distribution of incident particles was made by using the Real time Radiation Monitoring Device (RRMD)-III placed inside the Space Shuttle STS-84 cruised at an altitude of 400 km and an inclination angle of 51.6 degrees, which are the same as the cruising orbit of the International Space Station (ISS). The directional distributions of incident particles were evaluated over the observed linear energy transfer (LET) range (1-100 keV/micrometers). The pitch angle distribution is also obtained using the geomagnetic model of IGRF-95. The result is roughly in good agreement with the distribution obtained by the VF1-MIN anisotropy model calculation within the present experimental errors, if the shielding distribution is assumed to be uniform.

Anisotropy↗
PubMed1999

Significant differences in the frequency of transcriptional units, types and numbers of repetitive elements, GC content, and the number of CpG islands between a 1010-kb G-band genomic segment on chromosome 9q31.3 and a 1200-kb R-band genomic segment on chromosome 3p21.3.

We determined the nucleotide sequence of the entire 1,010,525-bp insert contained in CEPH YAC clone 867e8. This human genomic segment was derived from chromosome 9q31.3 and corresponds to a G-band region. We compared this segment, in terms of structure, with a previously characterized 1,201,033-bp sequence in CEPH YAC936c1 that had come from a portion of human chromosome 3p21.3 corresponding to an R-band region. The two segments were significantly different with respect to the frequency of transcriptional units, the types and numbers of repetitive elements present, their GC content, and the number of CpG islands. Alu elements, GC content, and CpG islands all showed positive correlations with the abundance of exons, but the distribution of LINE1s did not. These observations might reflect an influence of the first three of these features on the functions or expression of genes in the respective regions. In addition to a novel gene (F36) lying at the centromeric end of the 9q segment, we found a cluster of placenta-specific genes within a small section (about 400 kb) on the telomeric side of YAC867e8. This cluster consisted of four apparently unrelated ESTs and two genes, pregnancy-associated plasma protein-A (PAPP-A) and a novel gene (tentatively named EST-YD1). Our characterization of the two chromosomal regions provided evidence that genes are not evenly distributed throughout the human genome, and that gene richness is correlated with the GC content and with the frequency of either Alu elements or CpG islands.

Alu Elements↗
PubMed1999

Can coronary blood flow velocity pattern after primary percutaneous transluminal coronary angioplasty [correction of angiography] predict recovery of regional left ventricular function in patients with acute myocardial infarction?

BACKGROUND: In the era of primary percutaneous transluminal coronary angioplasty (PTCA), it is important to judge whether myocardium within acute ischemic injury is viable. This study sought to investigate parameters derived from the coronary blood flow velocity spectrum immediately after primary PTCA in patients with acute myocardial infarction and to elucidate the clinical value of coronary blood flow measurement in predicting myocardial viability. METHODS AND RESULTS: Using a Doppler guidewire, we measured coronary blood flow velocity after successful completion of primary PTCA in 23 consecutive patients with acute anterior myocardial infarction. Regional wall motion was analyzed to estimate anterior wall motion score index (A-WMSI) by echocardiography before PTCA and 1 month after the onset of symptoms. Average systolic peak velocity (ASV) and deceleration time of diastolic flow velocity (DDT) significantly correlated to 1-month A-WMSI (r=-0.54, P=0.007 and r=-0.62, P=0.002, respectively), and optimal cutoff values to predict viable myocardium (defined as 1-month A-WMSI </=2.0) were 6.5 cm/s for ASV and 600 ms for DDT (sensitivity=0.79, specificity=0.89 and sensitivity=0.86, specificity=0.89, respectively). ASV and DDT also correlated weakly to the change in A-WMSI (r=0.46, P=0.03 and r=0.49, P=0.02, respectively). CONCLUSIONS: Low ASV and rapid DDT of coronary blood flow spectrum immediately after primary PTCA reflects a greater degree of microvascular damage in the risk area. Analysis of coronary blood flow spectrum immediately after primary PTCA by use of a Doppler guidewire is useful in predicting recovery of regional left ventricular function.

Aged↗
PubMed1999

Genetic dissection of "OLETF," a rat model for non-insulin-dependent diabetes mellitus: quantitative trait locus analysis of (OLETF x BN) x OLETF.

To identify genetic determinants relevant to non-insulin-dependent diabetes mellitus (NIDDM), we performed a genome-wide analysis for quantitative trait loci (QTLs) using 359 backcross progeny of the Otsuka Long-Evans Tokushima Fatty (OLETF) rat. The OLETF strain is a well-studied animal model of obese NIDDM, with features of hyperinsulinemia, hyperglycemia, insulin resistance, and abundant abdominal fat. Our extensive genomic scanning with 218 markers revealed nine significant QTLs, including a strong determinant of obesity on chromosome 1 (Dmo1: LOD = 13.99, for body weight). Two highly significant QTLs for glucose homeostasis were found, one on chromosome 1 (Dmo4 LOD = 7.16, for postprandial glucose level) and the other on chromosome X (Dmo11/Odb1: LOD = 7.81, for postprandial glucose level). These data are comparable to results of our previous studies of the OLETF rat.

Adipose Tissue↗
PubMed1999

Determination of the site of disulfide linkage between heavy and light chains of silk fibroin produced by Bombyx mori.

The analysis of fibroin secretion-deficient 'naked-pupa' mutant silkworms has suggested that the disulfide linkage between heavy (H) and light (L) chains of fibroin, produced by the silkworm, Bombyx mori, is essential in its efficient large-scale secretion from the posterior silk gland cells. However, the site of disulfide-linkage between H- and L-chains has not been determined. In this study, cysteine residues involved in the single disulfide linkage between H- and L-chains were identified as the twentieth residue from the carboxyl terminus of H-chain (Cys-c20) and Cys-172 of L-chain by sequencing of genomic clones and peptide analysis. Furthermore, Cys-c4 (fourth residue from the carboxyl terminus) and Cys-c1 at the carboxyl terminus of H-chain were shown to form an intramolecular disulfide bond.

Amino Acid Sequence↗
PubMed1999

Human PIR1 of the protein-tyrosine phosphatase superfamily has RNA 5'-triphosphatase and diphosphatase activities.

A human cDNA was isolated encoding a protein with significant sequence similarity (41% identity) to the BVP RNA 5'-phosphatase from the Autographa californica nuclear polyhedrosis virus. This protein is a member of the protein-tyrosine phosphatase (PTP) superfamily and is identical to PIR1, shown by Yuan et al. (Yuan, Y., Da-Ming, L., and Sun, H. (1998) J. Biol. Chem. 272, 20347-20353) to be a nuclear protein that can associate with RNA or ribonucleoprotein complexes. We demonstrate that PIR1 removes two phosphates from the 5'-triphosphate end of RNA, but not from mononucleotide triphosphates. The specific activity of PIR1 with RNA is several orders of magnitude greater than that with the best protein substrates examined, suggesting that RNA is its physiological substrate. A 120-amino acid segment C-terminal to the PTP domain is not required for RNA phosphatase activity. We propose that PIR1 and its closest homologs, which include the metazoan mRNA capping enzymes, constitute a subgroup of the PTP family that use RNA as a substrate.

Acid Anhydride Hydrolases↗
PubMed1999

Effects of lipo prostaglandin E1 on distribution of cis-diamminedichloroplatinum in lung metastasis derived from Dunn osteosarcoma cell-inoculated mouse foot-pad.

This study was designed to determine the effect of lipid microspheres containing prostaglandin E1 (lipo PGE1) on cis-diamminedichloroplatinum (CDDP) accumulation in primary and lung metastatic lesions. Sixty mice were divided into four groups, depending on whether or not an intra-foot-pad injection of Dunn osteosarcoma cells had been administered and on whether or not an intraperitoneal injection of lipo PGE1 had been administered. CDDP was injected intraperitoneally into all the mice 6 weeks after the inoculation. Tumor colonies of spontaneous metastases in the left lung were found in 21 out of 30 tumor-inoculated mice at autopsy. Tissue platinum concentrations in the lungs with metastatic colonies and in the foot-pad tumors were significantly higher in the lipo PGE1-administered mice than in those without treatment. Terminal deoxytransferase-mediated dUTP nick end labeling (TUNEL) assay showed marked localization of dying cells in the lung metastatic lesions of the lipo PGE1-administered mice. The results of this study showed that pretreatment with lipo PGE1 may augment the antitumor effects of CDDP at the tumor site.

Alprostadil↗
PubMed1999

A Saccharomyces cerevisiae RNA 5'-triphosphatase related to mRNA capping enzyme.

The Saccharomyces cerevisiae mRNA capping enzyme consists of two subunits: the RNA 5'-triphosphatase (Cet1) and the mRNA guanylyltransferase (Ceg1). Using computer homology searching, a S. cerevisiae gene was identified that encodes a protein resembling the C-terminal region of Cet1. Accordingly, we designated this gene CTL1 (capping enzyme RNAtriphosphatase-like 1). CTL1 is not essential for cell viability and no genetic or physical interactions with the capping enzyme genes were observed. The protein is found in both the nucleus and cytoplasm. Recombinant Ctl1 protein releases gamma-phosphate from the 5'-end of RNA to produce a diphosphate terminus. The enzyme is specific for polynucleotide RNA in the presence of magnesium, but becomes specific for nucleotide triphosphates in the presence of manganese. Ctl1 is the second member of the yeast RNA triphosphatase family, but is probably involved in an RNA processing event other than mRNA capping.

Acid Anhydride Hydrolases↗
PubMed1999

Characterization of the myosin light chain kinase from smooth muscle as an actin-binding protein that assembles actin filaments in vitro.

In addition to its kinase activity, myosin light chain kinase has an actin-binding activity, which results in bundling of actin filaments [Hayakawa et al., Biochem. Biophys. Res. Commun. 199, 786-791, 1994]. There are two actin-binding sites on the kinase: calcium- and calmodulin-sensitive and insensitive sites [Ye et al., J. Biol. Chem. 272, 32182-32189, 1997]. The calcium/calmodulin-sensitive, actin-binding site is located at Asp2-Pro41 and the insensitive site is at Ser138-Met213. The cyanogen bromide fragment, consisting of Asp2-Met213, is furnished with both sites and is the actin-binding core of myosin light chain kinase. Cross-linking between the two sites assembles actin filaments into bundles. Breaking of actin-binding at the calcium/calmodulin-sensitive site by calcium/calmodulin disassembles the bundles.

Actin Cytoskeleton↗
PubMed1999

NELF, a multisubunit complex containing RD, cooperates with DSIF to repress RNA polymerase II elongation.

DRB is a classic inhibitor of transcription elongation by RNA polymerase II (pol II). Since DRB generally affects class II genes, factors involved in this process must play fundamental roles in pol II elongation. Recently, two elongation factors essential for DRB action were identified, namely DSIF and P-TEFb. Here we describe the identification and purification from HeLa nuclear extract of a third protein factor required for DRB-sensitive transcription. This factor, termed negative elongation factor (NELF), cooperates with DSIF and strongly represses pol II elongation. This repression is reversed by P-TEFb-dependent phosphorylation of the pol II C-terminal domain. NELF is composed of five polypeptides, the smallest of which is identical to RD, a putative RNA-binding protein of unknown function. This study reveals a molecular mechanism for DRB action and a regulatory network of positive and negative elongation factors.

Amino Acid Sequence↗
PubMed1999

Noninvasive assessment of hemodynamic subsets in patients with acute myocardial infarction using digital color Doppler velocity profile integration and pulmonary venous flow analysis.

Four major hemodynamic subsets from cardiac index (CI) and mean pulmonary artery (PA) wedge pressure with a PA catheter usually reflect clinical status and prognosis of patients with acute myocardial infarction (AMI). Recently, a new color Doppler technique has been developed for automated cardiac output measurements (ACOM). Color Doppler echocardiography also provides noninvasive estimation of PA wedge pressure from pulmonary venous (PV) flow analysis. This study evaluates the value of ACOM and PV flow analysis by color Doppler echocardiography for the assessment of hemodynamic subsets in patients with AMI. We performed ACOM and PV flow analysis by color Doppler echocardiography in 55 patients with AMI who underwent hemodynamic assessment with a PA catheter. From both noninvasive and invasive methods, we classified hemodynamic subsets as follows: subset I: normal hemodynamics (CI >2.2 L/min/m2, PA wedge pressure < or =18 mm Hg); subset II: pulmonary congestion (CI >2.2 L/min/m2, PA wedge pressure >18 mm Hg); subset III: peripheral hypoperfusion (CI < or =2.2 L/min/m2, PA wedge pressure < or =18 mm Hg); and subset IV: pulmonary congestion and peripheral hypoperfusion (CI < or =2.2 L/min/m2, PA wedge pressure >18 mm Hg). Doppler assessment of hemodynamic subsets was possible in 50 of 55 patients (91%). CI from ACOM correlated well with that from the thermodilution method (r = 0.94) with close agreement. There was a good correlation between the systolic fraction (systolic velocity-time integral expressed as a fraction of the sum of systolic and diastolic velocity-time integrals) of PV flow and PA wedge pressure measured from cardiac catheterization (r = -0.83). When we determined the value of 45% in the systolic fraction as the cut-off point in predicting >18 mm Hg in PA wedge pressure, there was 90% (45 of 50 patients) agreement between noninvasive and invasive hemodynamic subsets. Thus, ACOM and PV flow analysis by color Doppler echocardiography is useful in the noninvasive assessment of hemodynamic subsets in patients with AMI.

Adult↗
PubMed1999

Structure and function of the human transcription elongation factor DSIF.

5,6-Dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) is a classic inhibitor of transcription elongation by RNA polymerase II (pol II). We have previously identified and purified a novel transcription elongation factor, termed DSIF (for DRB sensitivity-inducing factor), that makes transcription sensitive to DRB. DSIF is composed of 160- and 14-kDa subunits, which are homologs of the Saccharomyces cerevisiae transcription factors Spt5 and Spt4. DSIF may either repress or stimulate transcription in vitro, depending on conditions, but its physiological function remains elusive. Here we characterize the structure and function of DSIF p160. p160 is shown to be a ubiquitous nuclear protein that forms a stable complex with p14 and interacts directly with the pol II largest subunit. Mutation analysis of p160 is used to identify structural features essential for its in vitro activity and to map the domains required for its interaction with p14 and pol II. Finally, a p160 mutant that represses DSIF activity in a dominant-negative manner is identified and used to demonstrate that DSIF represses transcription from various promoters in vivo.

Amino Acid Sequence↗
PubMed1999

The structural organization of the ascidian, Halocynthia roretzi, calmodulin genes. The vicissitude of introns during the evolution of calmodulin genes.

Two distinct calmodulin (CaM) genes are isolated from the ascidian, Halocynthia roretzi, (Hr-CaM A and Hr-CaM B) and those structures are determined. There are three nucleotide substitutions, producing two amino acid differences between Hr-CaM A and Hr-CaM B, and those are corresponding to two of the known eight variable residues among metazoan CaMs. Both Hr-CaM A and Hr-CaM B are constructed from six exons and five introns, and the positions of introns are identical. The positions of introns of Hr-CaMs are also identical with those of vertebrate CaMs, except third introns. The third introns of Hr-CaMs are inserted at 28bp upstream when compared with vertebrate CaMs. Thus, sliding of the third intron might have occurred in only the ascidian lineage prior to the gene duplication that also occurred only in that lineage. In addition, with the comparison of the intron positions, we attempt to investigate the vicissitude of introns during the evolution of metazoan CaMs.

Amino Acid Sequence↗
PubMed1999

Characterization of a 1200-kb genomic segment of chromosome 3p22-p21.3.

We previously determined the nucleotide sequence and characterized the 685-kb proximal half of CEPH YAC936c1, which corresponds to a portion of human chromosome 3p21.3. In the study reported here, we characterized the remaining 515-kb of this YAC clone corresponding to the telomeric half of its human insert. The newly sequenced region contained a total of ten genes including six reported previously: phospholipase C delta 1 (PLCD1), human activin receptor type IIB (hActR-IIB), organic cation transporter-like 1 (OCTL1), organic cation transporter-like 2 (OCTL2), oxidative stress response 1 (OSR1), and human xylulokinase-like protein (XYLB). The remaining four genes present in the telomeric region included two known genes, MyD88 and ACAA, and two novel genes. One (designated ENGL) of the novel sequences was found to encode an amino-acid sequence homologous to the family of DNA/RNA endonucleases, especially endonuclease G. The other gene F56 revealed no significant homology to any known genes. These results disclosed complete physical and transcriptional maps of the 1200-kb region of 3p present in YAC 936c1.

Amino Acid Sequence↗
PubMed1999

Neutral glycolipid and ganglioside composition of type-1 and type-2 astrocytes from rat cerebral hemisphere.

We reported previously that the major gangliosides in primary mixed-type astrocyte cultures are GM3 and GD3. To obtain more information regarding the exact distribution of glycosphingolipids in different types of astrocytes, we established a line of type-1 astrocytes that are characterized by a Ran-2 positive, broad flat morphology, and by the absence of binding to A2B5 antibodies. We also purified O-2A progenitor cells by immunopanning and cultured them in the presence of 10% newborn calf serum. They differentiated into type-2 astrocytes that were identified by immunostaining for each of GD3, A2B5, and GFAP. Using these cell cultures, we demonstrate that the major gangliosides were GM3 in type-1 astrocytes and GM3 and GD3 in type-2 astrocytes. In addition, a set of neutral glycolipids was identified based on the HP-TLC migration properties of CMH, CDH, CTH, and Glob, but the component distribution of these glycolipids is related to that of glycolipids of astrocytes. A marked increase in the expression of CTH and Glob was shown in type-2 astrocytes. The amount of neutral glycolipid-sugar was higher in the type-2 astrocytes than in the type-1 astrocytes. These results suggest that the increase in the total glycosphingolipid content and the change in the neutral glycolipid composition produced by type-2 astrocytes may be related to their biological functions and the cellular compositions.

Animals↗
PubMed1999

Primary Non-Hodgkin's Lymphoma of the Male Breast: A Case Report.

A 69-year-old Japanese man presented with bilateral gynecomastia and a soft, mobile and clearly defined mass beneath the left nipple. A round radiopaque masswas revealed on mammography. The tumor was homogeneous, hypoechoic and measured2.4 x 3.9 cm on ultrasonography. Based on a diagnosis of malignant lymphoma by needle aspiration cytology, a modified radical mastectomy with ipsilateral axillary lymph node dissection was performed. Malignant diffuse large B-cell type lymphoma was diagnosed histologically. Whole body examinations revealed no evidenceof other tumors. Three courses of adjuvant CHOP therapy were subsequently performed. The patient is free of recurrence 12 months after surgery. Primary non-Hodgkin's lymphoma (NHL) of the male breast is extremely rare. The occurrence of lymphoma in this patient could be related to elevated estrogen levels.

Journal Article↗