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H Hayashi

Publications and source records attributed to H Hayashi.

At least 703 records · Page 39Linked to original sources
PubMed1996

[A new three-dimensional CT reconstruction method for cerebral arteriovenous malformation: development and clinical evaluation of see-through view method].

The authors developed a new three-dimensional reconstruction method called "See-Through View (STV)" using a spiral CT in evaluating of cerebral arteriovenous malformation (AVM). Spiral CT was performed in eight patients with AVM. STV was obtained by reconstructing with a voxel transmission projection using a double threshold method. In all eight patients, STV images enable us to depict the nidus of AVM from all angles by see-throughing skull bone, evaluating the relationship of the vascular lesions adjacent to other cerebrovascular or skeletal structures. In conclusion, STV will provide us further spatial recognition, and will be greatly helpful for surgical planning.

Adult↗
PubMed1996

Alloresistance to K locus class I-mismatched bone marrow engraftment is mediated entirely by CD4+ and CD8+ T cells.

Clinical application of approaches to inducing transplantation tolerance that involve bone marrow reconstitution will require achievement of engraftment without major toxicity to the recipient. These requirements are likely to vary according to the type of histoincompatibility between donor and recipient. We have attempted to determine the minimal conditioning required to achieve lasting mixed allogeneic chimerism and tolerance in the presence of a class I MHC disparity by evaluating the host elements that resist alloengraftment. We based our approach on a regimen that was shown to induce mixed chimerism in fully MHC-mismatched strain combinations. Recipient B10.AKM (KkIkDq) mice were treated with 7 Gy thymic irradiation (TI) and 3 Gy whole body irradiation (WBI) and received either anti-CD8 mAb alone or anti-CD4 plus anti-CD8 mAbs before transplantation of K locus-disparate B10.MBR (KbIkDq) marrow. All (27 of 27) animals receiving both mAbs showed lasting multi-lineage mixed chimerism and donor-specific tolerance. In contrast, five of 22 (23%) recipients pre-treated with anti-CD8 mAb alone in the same experiments failed to develop lasting multilineage mixed chimerism, suggesting that the CD4 T cell subset also participates in resistance to class I-mismatched marrow engraftment. We next attempted to determine whether or not host non-T cell elements resist allogeneic engraftment by comparing the minimum number of syngeneic vs allogeneic BMC required to achieve lasting multilineage mixed chimerism. Titrated numbers (10(6) to 10(7)) of B10.MBR (KbIkDq) bone marrow cells were administered to B10.AKM recipients treated with anti-CD4 and -CD8 mAbs, 3 Gy WBI and 7 Gy TI. All recipients of each marrow dose developed lasting multilineage mixed chimerism and showed specific tolerance to B10.MBR skin grafts. The level of donor-type repopulation in recipients of each dose was not lower than that observed in similarly irradiated recipients in an Ly5 congenic, otherwise syngeneic, BMT system. Together, our results suggest that CD4+ T cells contribute to resistance to K locus class I-mismatched marrow allografts and that resistance is mediated only by CD4 and CD8 T cells, with no role for non-T cell host elements.

Animals↗
PubMed1996

[Immunodetection of vascular endothelial growth factor in the vitreous of eyes with proliferative diabetic retinopathy].

To determine the association of a hypoxia-induced, vascular endothelial cell selective growth factor: vascular endothelial growth factor (VEGF) on proliferative diabetic retinopathy (PDR), undiluted vitreous fluids were collected from 10 eyes with PDR at the time of vitrectomy. Vitreous fluids from 10 eyes without PDR were used as control. All samples were electrophoresed with a 14% sodium dodesyl sulfatepolyacrylamide gel, and electrically transferred to a Durapore membrane. Immunoblot detection of VEGF was done by standard western blotting using rabbit polyclonal anti-human VEGF antibody. Positive immunoreaction bands were observed on lanes of 7 samples from PDR, and they were comigrated with recombinant human VEGF. No reactions were observed on lanes of all samples without PDR. The presence of VEGF within the vitreous fluids of eyes with PDR was determined, and suggesting the association of VEGF with PDR.

Adolescent↗
PubMed1996

[Transesophageal echocardiography (Part 4): clinical application. Part 2].

Transesophageal echocardiography (TEE) is extremely useful in evaluating native and prosthetic valves. TEE can reveal valvular lesions that may not be demonstrated by transthoracic approach. Nonetheless significant findings could be overlooked or misinterpreted even with TEE, since three-dimensional structures, motions, or flows are assessed through two-dimensional images. In addition, changes in the imaging conditions can considerably affect echo images, and thereby their interpretation. These inherent limitations of the technique must be kept in mind, and diagnosis should be based not only on echographic findings but on hemodynamic conditions and clinical observations. Other applications of intraoperative TEE include detection of intracardiac thrombi, tumors and vegetations, visualization of air bubbles, positioning of an intraaortic balloon and a coronary sinus catheter, evaluation of thoracic aortic lesions and pleural effusion, etc. In particular, TEE exhibits excellent sensitivity and specificity in diagnosing aortic dissection, and is indicated as a first-line examination when urgent evaluation is required for acute aortic dissection.

Aortic Dissection↗
PubMed1996

[Atypical mycobacteriosis (Mycobacterium xenopi) with "initial aggravation"].

A 66-year-old man was admitted to Nara Medical University Hospital because of sputum production and fevre. A chest X-ray film obtained on admission revealed many cysts and an infiltrative shadow in the right upper lung field. The patient was treated with antimycobacterial drugs (isoniazid 400 mg, streptomycin 0.75 g, and rifampicin 450 mg) because acid-fast bacilli were detected in his sputum. Although the symptoms and laboratory data improved, a new infiltrative shadow developed in the right lower lung field two months after the start of treatment. Transbronchial biopsy specimens showed intraluminal organizing exudate and alveolitis. The new lesion resolved when treated with the same antimycobacterial drugs. Mycobacterium xenopi was cultured from the sputum 80 days later. This is the third reported case of atypical mycobacteriosis (non-tuberculous mycobacteriosis) due to M. xenopi in Japan with the "initial aggravation" seen in some patients with typical pulmonary tuberculosis.

Aged↗
PubMed1996

[Three-dimensional measurement of vascular lesions with virtual CT endoscopy "cruising eye view" method].

The purpose of this report is to propose a new technique which allows three-dimensional measurement of vascular lesions based on the virtual CT endoscopy "Cruising-Eye-View (CEV)" method. The view-point of CEV imagings was used as measuring point of vascular lesions. Using this technique, we could measure the actual length of arterial stenosis along the vessel in 3 patients with arteriosclerosis obliterans. The three-dimensional measuring technique with the CEV method may become a useful tool in treatment planning before interventional radiology, including metallic stent placement.

Angiography↗
PubMed1996

Isolation of a novel chick homolog of Serrate and its coexpression with C-Notch-1 in chick development.

Intercellular signaling mediated by the transmembrane proteins, Notch as receptor and its ligands, Delta and Serrate, plays essential roles in the developmental fate decision of many cell types in Drosophila. The Notch genes are highly conserved both in invertebrates and in vertebrates, suggesting that Notch pathway regulates cell fate decisions during vertebrates development. Notch, Delta and Serrate homologs in chicken have been cloned (Henrique et al., Nature 375: 787-790, 1995; Myat et al., Dev. Biol. 174: 233-247, 1996). We isolated a novel chick homolog of Drosophila Serrate, named C-Serrate-2, and examined its expression patterns during the early chick development using whole-mount in situ hybridization. C-Serrate-2 transcripts were detected in several tissues including the forebrain, the myotome and the apical ectodermal ridge (AER) of the limb bud of a 4-day-old chick embryo. In most of the regions where C-Serrate-2 was expressed, C-Notch-1 was also expressed. Our observations suggest that Serrate-2-Notch-1 signaling plays a role in a variety of morphogeneses during the chick development.

Amino Acid Sequence↗
PubMed1996

Mutagenicity study of the new cephalosporin antibiotic cefditoren pivoxil.

The mutagenicity of a cephalosporin antibiotic, (-)-(6R,7R)-2,2-dimethylpropionyloxymethyl 7-[(Z)-2-(2-aminothiazol-4-yl)-2-methoxyiminoacetamido]-3-[(Z)-2- (4-methylthiazol-5-yl) ethenyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate (cefditoren pivoxil, CAS 117467-28-4, CDTR-PI), was evaluated by various mutagenicity tests as follows: the reverse mutation assay in bacteria, the chromosomal aberration test with Chinese hamster CHL cells, the micronucleus test with mice, the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus gene mutation test with L5178Y cells, the chromosomal aberration test with human lymphocytes, the unscheduled DNA synthesis test with rat stomach mucosa cells, and the cell transformation test with BALB/3T3 cells. CDTR-PI induced the structural chromosomal aberrations considered direct action in the chromosomal aberration test with CHL cells at concentrations of 150 micrograms/ml and more, but in none of the other mutagenicity tests even in excessive doses. Evaluation for clastogenicity with metabolites of CDTR-PI and checking for formaldehyde generation in the culture medium appeared to verify that the original source of the clastogenicity of this antibiotic was a formaldehyde generated from a pivoxil radical of CDTR-PI. The carcinogenicity of formaldehyde has been reported as negative in rats administered orally for 2 years. These results suggested the CDTR-PI would reveal neither mutagenicity nor carcinogenicity under clinical conditions.

3T3 Cells↗
PubMed1996

Molcecular cloning of human antizyme cDNA.

We have cloned the cDNA encoding the human ornithine decarboxylase antizyme from a 5'-stretch cDNA library of human B-cell lymphoma Daudi. The cloned human antizyme cDNA fragment consists of 1063 bp, has 80% homology to the rat antizyme cDNA, but shows almost no homology to the E. coli antizyme gene. Northern hybridization analysis shows that this gene is expressed in a number of human cell lines with an estimated mRNA transcript size of about 1.1 kb. The size of the mRNA suggests that the cloned cDNA fragment probably represents the full length of human antizyme mRNA transcript. Comparison of the human and rat antizymes demonstrates that they are highly conserved at both nucleotide and peptide levels.

Amino Acid Sequence↗
PubMed1995

Cloning of cDNA for rat eosinophil major basic protein.

We have determined the complete nucleotide sequence for the cDNA encoding rat eosinophil major basic protein (MBP) using the rapid amplification of cDNA ends (RACE) procedure. The deduced amino acid sequence revealed that the rat prepro-MBP has three functional domains, namely the signal peptide, the acidic peptide that contains numerous acidic amino acids, and the mature MBP, as in human and guinea pig MBP.

Amino Acid Sequence↗
PubMed1995

Cloning of a cDNA encoding a 190-kDa insulin receptor substrate-1-like protein of simian COS cells.

Major insulin signals such as stimulation of glucose uptake and DNA synthesis and modification of hexose metabolism are mediated by the tyrosine-phosphorylated insulin receptor substrate-1 (IRS-1; pp180) in many species of cells. We cloned cDNA encoding a 190-kDa IRS-1-like protein (pp190) in simian COS cells and which is slightly larger than IRS-1 (pp180) of human, rat, and mouse cells. The deduced amino acid sequence of COS pp190 consisted of 1251 amino acids and was 96.4%, 87.9% and 88.7% identical to human, mouse and rat IRS-1. The COS pp190 bound to SH2 (src-homology 2) domains of p85, Grb2/Ash, and SH-PTP2, as did IRS-1. In IRS-1-knockout mice, insulin signals are thought to be mediated by IRS-2 (pp190), which is an alternative signaling molecule and is slightly larger than IRS-1. However, the COS pp190 may be a simian homologue of IRS-1, but not of IRS-2. The results of Southern blotting suggested the possibility that Chinese hamster ovary (CHO) cells have not only the IRS-1 gene but also a gene related to the COS pp190.

Amino Acid Sequence↗
PubMed1995

Diagnostic usefulness of postexercise systolic blood pressure response for detection of coronary artery disease in patients with electrocardiographic left ventricular hypertrophy.

Patients with left ventricular (LV) hypertrophy often have a positive result on exercise testing despite a normal coronary arteriogram. This indicates that exercise-induced ST depression is not always an accurate indicator of the presence of coronary artery disease (CAD) in such patients. We evaluated the usefulness of the postexercise systolic blood pressure (BP) response for detection of CAD in 51 patients with both electrocardiographic evidence of LV hypertrophy and positive ST depression on treadmill exercise testing. Coronary cineangiograms showed normal coronary arteries in 23 patients (45%) (group 1) and significant CAD in 28 patients (55%) (group 2). The systolic BP ratio (systolic BP at 3 minutes of recovery divided by systolic BP at peak exercise) was significantly higher in group 2 than in group 1 (1.01 +/- 0.19 vs 0.80 +/- 0.09; p < 0.001). Analysis of the relative cumulative frequency revealed that a systolic BP ratio of 0.86 was the cutoff point for distinguishing a patient with CAD from one with normal coronary arteries. The sensitivity, specificity, and accuracy of a systolic BP ratio > or = 0.86 for detection of CAD in patients with LV hypertrophy were 79%, 83%, and 82%, respectively. Our results suggest that the use of an abnormal BP ratio, in combination with ST depression, improves the accuracy of treadmill exercise testing for detecting CAD in patients with electrocardiographic evidence of LV hypertrophy.

Adult↗
PubMed1995

Transcriptional analysis of the beta-galactosidase gene (pbg) in Clostridium perfringens.

The mode of expression of the beta-galactosidase gene (pbg) of Clostridium perfringens was examined. The pbg gene was transcribed on a single 3.7-kb mRNA. The transcript contained a message for ORF54, located upstream of the pbg gene in the chromosome, indicating that ORF54 and the pbg gene comprise one operon (pbg operon). Expression of the pbg operon was induced by lactose at the transcriptional level. The promoter structure of the pbg operon was characterized by many palindrome structures and direct repeats, which suggests that there might be some catabolite regulation of the expression of the pbg operon in C. perfringens.

Base Sequence↗
PubMed1995

The amino acid sequence and interaction with the nucleosome core DNA of transition protein 4 from boar late spermatid nuclei.

The primary structure of transition protein 4 (TP4) from boar late spermatid nuclei was determined by automated Edman degradation of S-pyridylethylated protein and of peptides generated by cleavage with Staphylococcus aureus V8 protease, lysyl endopeptidase and CNBr. Boar TP4 is a basic protein consisting of a highly basic amino-terminal half (residues 1-73) and a less basic carboxy-terminal half (residues 74-138). The latter half includes a highly hydrophobic segment, a four-times tandemly repeated sequence, N(G)QNKR(K)X, and a carboxy-terminal segment containing Trp126. Ultraviolet absorption and CD spectra of TP4-rat-liver-nucleosome-core-DNA (double-stranded DNA) complexes suggest a TP4-induced local melting of DNA. Although at 1 mM NaCl TP4 brought about a slight stabilization of the DNA against thermal melting, a destabilization of the DNA was observed at 50 mM NaCl. From the results of quenching of tryptophan (Trp126) fluorescence of TP4 upon its binding to double-stranded and single-stranded boar liver nucleosome-core DNA at 50 mM NaCl, the apparent association constants for the binding of TP4 to double-stranded and single-stranded DNA were calculated to be 7.3 x 10(3) M-1 and 4.1 x 10(3) M-1, respectively. These results suggest that TP4, having different domain structures from TP1-3 and a higher affinity for double-stranded DNA, induces a local destabilization of DNA probably through the stacking of Trp126 with nucleic acid bases.

Amino Acid Sequence↗
PubMed1995

Possible domains responsible for intracellular targeting and insulin-dependent translocation of glucose transporter type 4.

Translocation of the type 4 glucose transporter (GLUT4) to the cell surface from an intracellular pool is the major mechanism of insulin-stimulated glucose uptake in insulin-target cells. We developed a highly sensitive and quantitative method to detect GLUT4 immunologically on the surface of intact cells, using c-myc epitope-tagged GLUT4 (GLUT4myc). We constructed c-myc epitope-tagged glucose transporter type 1 (GLUT1myc) and found that the GLUT1myc was also translocated to the cell surface of Chinese hamster ovary cells, 3T3-L1 fibroblasts and NIH 3T3 cells, in response to insulin, but the degree of translocation was less than that of GLUT4myc. Since GLUT1 and GLUT4 have different intracellular distributions and different degrees of insulin-stimulated translocation, we examined the domains of GLUT4, using c-myc epitope-tagged chimeric glucose transporters between these two isoforms. The results indicated that, (1) all the cytoplasmic N-terminal region, middle intracellular loop and cytoplasmic C-terminal region of GLUT4 have independent intracellular targeting signals, (2) these sequences for intracellular targeting of GLUT4 were not sufficient to determine GLUT4 translocation in response to insulin, and (3) the N-terminal half of GLUT4 devoid both of cytoplasmic N-terminus and of middle intracellular loop seems to be necessary for insulin-stimulated GLUT4 translocation.

3T3 Cells↗
PubMed1995

Reaction of aspartate aminotransferase with L-erythro-3-hydroxyaspartate: involvement of Tyr70 in stabilization of the catalytic intermediates.

The reaction of Escherichia coli aspartate aminotransferase (AspAT) with L-erythro-3-hydroxyaspartate (HOAsp) produces an intense absorption at 494 nm (epsilon = 13,650 M-1 cm-1), which is ascribed to the quinonoid intermediate. However, when Tyr70 of AspAT has been replaced by Phe, the enzyme shows only a faint absorption at 494 nm (epsilon = 522 M-1 cm-1) on the reaction with HOAsp. This indicates the involvement of the hydroxy group of Tyr70 in stabilizing the quinonoid intermediate formed from HOAsp and pyridoxal 5'-phosphate at the AspAT active site. Kinetic analysis of the absorption changes of the wild-type and Y70F mutant AspATs has shown that the reactions with HOAsp conform to the equation, EL + S<-->ES1<-->ES2<-->ES3<-->EM + P, in which there is a rapid formation of the quinonoid intermediate (ES2) from ES1, followed by a slow equilibrium between ES2 and ES3. ES3 absorbs primarily at 330 nm. The kinetic parameters for individual steps have been determined, and free energy profiles for the reactions of the two enzymes with HOAsp have been obtained. The stability of the quinonoid intermediates of the two enzymes in the normal catalytic reactions with aspartate has been assessed by static measurement of the spectra in the presence of both aspartate and oxalacetate, and the free energy profiles for the reactions have been similarly obtained. Comparison of the free energy levels in the profiles showed that the interaction of the beta-hydroxy group of HOAsp with the hydroxy group of Tyr70 accounts for 8.7 kJ mol-1 of the 18.5 kJ mol-1 stabilization of the quinonoid intermediate by the beta-hydroxy group. Model building of the active site of AspAT complexed with HOAsp suggests that the rest of the stabilization is mediated through the interaction of the beta-hydroxy group of HOAsp with the protonated epsilon-amino group of Lys258. This interaction is expected to strengthen the hydrogen-bonding network involving Tyr70, HOAsp, and the coenzyme phosphate. A similar network is possibly formed in the carbinolamine intermediate, suggesting ES3 to be the carbinolamine. A mechanism for the reaction of AspAT with HOAsp, which conforms to all the kinetic and spectroscopic data presented here, is proposed. This study provides a basis for subsequent spectroscopic characterization of the HOAsp-AspAT complex, which is a good model for the critical intermediate (quinonoid) structure of the AspAT-catalyzed reactions.

Amino Acid Sequence↗
PubMed1995

Chaotic responses of the hippocampal CA3 region to a mossy fiber stimulation in vitro.

Undoubted evidence of chaotic activity of a biological neural network are given. Spontaneous epileptiform bursts of a neuron population in the CA3 region of rat hippocampal slices were caused in a perfusing medium with 2 mM penicillin and 8 mM K+ ions, and responses of field potential in the CA3 region to a periodic mossy fiber stimulation were investigated. Phase-locked and chaotic responses occur depending on stimulus parameters; for example, when the frequency of the stimulation increases, 1:1 phase-locking bifurcates to chaos through 1:2 phase-locking. The chaotic responses show a broad-band spectrum, and their trajectories in the three-dimensional phase space (V(t), V(t + tau), V(t + 2 tau)) reconstruct a strange attractor. Lyapunov exponents of the strange attractors estimated by the Wolf's algorithm are positive. Moreover, one-dimensional strobomaps obtained from the chaotic responses show a non-invertible function. Since the slope of each strobomap at their fixed point is more negative than -1, the fixed points are unstable. These are undoubted evidences for chaotic responses of the CA3 region in hippocampal slices maintained in vitro. Cross-correlation functions between field potential responses which were simultaneously observed at different sites show that the responses are spatially coherent throughout the CA3 region even when the responses are chaotic.

Action Potentials↗