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Biomedical subjects

Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 865 records · Page 48Linked to original sources
PubMed1993

Inhibition of high-molecular-weight-(1-->3)-beta-D-glucan-dependent activation of a limulus coagulation factor G by laminaran oligosaccharides and curdlan degradation products.

Extensive surveys for the effects of various beta-D-glucans on the coagulation cascade in horseshoe crab amebocyte lysates showed that low-mol-wt-(1-->3)-beta-D-glucans and laminaran oligosaccharides inhibit the activation of a limulus coagulation factor G by high-mol-wt-(1-->3)-beta-D-glucans. The inhibitory properties are exclusively dependent upon their number-average mol wt (Mn) in a range of 342-58,100, which correspond to a degree of polymerization (dp) range of 2-359. The most effective is a laminaran dextrin of Mn 5800 (dp of 35-36), which causes 50% inhibition of factor G activation at a concentration of 3.16 ng/mL. The inhibition of the activation of factor G proportional to the concentration of the inhibitor, and the adsorption of factor G by inhibitory beta-D-glucan-conjugated cellulose suggested a high affinity of the inhibitory saccharides for the activator-recognition site of factor G. Branched (1-->6), (1-->3)-beta-D-glucans, laminarans, mixed linkage (1-->3), (1-->4)-beta-D-glucans, and partially substituted curdlan and laminaran were found to be inhibitory, possibly owing to clusters of consecutive (1-->3)-beta-D-glucopyranosyl residues as intrachain units. The inhibition appears to be related to the inability of the inhibitory (1-->3)-beta-D-glucans to form ordered conformations and to their tendency to take a random-coil structure in aqueous solution.

Animals↗
PubMed1993

Identification of the fragment photoaffinity-labeled with azidodansyl-rhizoxin as Met-363-Lys-379 on beta-tubulin.

The rhizoxin (RZX)-binding site on porcine brain tubulin was investigated by photoaffinity labeling with the 5-azido-1-naphthalene sulfonyl (azidodansyl) derivative of RZX, nor-rhizoxin-22-al-5'-azidonaphthalene-1'-sulfonylhydrazo ne (azidodansylrhizoxin: Adan-RZX). Upon ultraviolet irradiation, Adan-RZX generates a highly reactive nitrene, which irreversibly binds to an amino acid residue(s) near the RZX-binding site. The label was found to be on beta-tubulin. Enzymatic digestion of the labeled tubulin generated only one major fluorescent peak on C18 reverse phase HPLC analysis. The labeled site(s) was mapped by using various combinations of highly specific peptidases in succession. That is, the labeled fragment generated by the first peptidase was purified by HPLC and exposed to a second peptidase; if the retention time in HPLC changed after the second digestion, the fragment generated in the first digestion must have contained the recognition site(s) of the second enzyme. From the results of these successive digestions and the known polypeptide sequences, we could identify the labeled fragment as Met-363-Lys-379 of beta-tubulin. This peptidase combination technique should be widely applicable.

Affinity Labels↗
PubMed1993

Cytokinin-specific binding protein in etiolated mung bean seedlings.

We have found that a synthetic urea derivative, N-(2-chloro-4-pyridyl)-N'-phenylurea (4PU30, forchlorfenuron), has even higher cytokinin activity than N6-benzyladenine (BA). Using [3H]4PU30 (2.83 TBq/mmol) as a probe, we confirmed chromatographically the presence of a high-affinity cytokinin-specific binding protein (CSBP) in whole-cell extract from etiolated mung bean seedlings. The apparent molecular weight of CSBP was estimated to be 21 kDa. The association constants (Ka's) of CSBP for 4PU30 and BA were calculated to be 4 x 10(10) M-1 and 3 x 10(9) M-1, respectively. Various active cytokinins showed mutually competitive binding to CSBP, and their affinities for CSBP corresponded well to their cytokinin activities at the tissue level.

Arabidopsis Proteins↗
PubMed1993

Enhanced binding to antigen of monoclonal antibodies modified with a crosslinker.

Modification of monoclonal antibodies (mAbs) with a photo-crosslinker, sulfosuccinimidyl 2-(m-azido-o-nitrobenzamido)-ethyl-1, 3'-dithiopropionate (SAND), enhanced their antigen binding activity. By SAND modification, SV2-61 gamma mAb against human c-erbB-2 protooncogene product could immunoprecipitate approximately an 8-fold greater amount of antigen, and AB-3 mAb against bovine serum albumin (BSA) bound to BSA more efficiently than unmodified mAb as determined by an enzyme-linked immunosorbent assay. Relative binding affinity of SAND-modified AB-3 was about 4-fold of unmodified AB-3. Augmented binding of mAbs was observed with or without photosensitization.

Antibodies, Monoclonal↗
PubMed1993

Recombinase activating gene expression in thymic subpopulations. A transitional cell type has lost RAG-2 but not RAG-1.

We have used a highly sensitive Northern blot probing technique to examine RAG-1 and RAG-2 mRNA expression in unmanipulated murine thymocytes of various developmental phenotypes sorted by flow cytometry. We have found that neither RAG-1 nor RAG-2 are down-regulated until thymocytes reach the TCRhi stage. TCRhi, CD8+CD4+ cells have lost RAG-2 mRNA but continue to express significant levels of RAG-1 mRNA, providing molecular evidence that this cell type is transitional between the TCRlo, CD4+CD8+ and the TCRhi, CD4+CD8-, or CD4-CD8+ phenotypes.

Animals↗
PubMed1993

Preliminary investigation of crystals of lipase I from Rhizopus niveus.

Lipase I from Rhizopus niveus consists of two polypeptide chains bound non-covalently. Lipase I has been crystallized in a form suitable for X-ray diffraction analysis using the hanging drop method of vapour diffusion at 20 degrees C. The crystals grew at pH 6.0 to 7.0 using 14 to 16% polyethylene glycol 8000 as the precipitant. The crystals are tetragonal with space group P4(1) (or P4(3)) and cell dimensions of a = b = 83.7 A, c = 137.9 A. There are two protein molecules in the asymmetric unit. The diffraction pattern extends to at least 2.5 A resolution.

Lipase↗
PubMed1993

Malignant lymphoma originating from the earliest T-lineage precursor cell.

The earliest T-lineage precursor cells with a CD3-CD4+CD8- phenotype and germline-state T-cell receptor (TCR) genes have recently been identified in the murine thymus. We report a case of malignant lymphoma that was considered to originate from the human counterpart of this newly defined murine T-cell population. The surface phenotype of the lymphoma cells was CD2+CD3-CD4+CD8-CD25-CD34-CD44+HLA-DR+. TCR-beta, -gamma, -delta chain genes and immunoglobulin heavy and light chain genes were all in a germline state. These characteristics were markedly similar to those of the murine earliest T-lineage precursor cells. The present case thus strongly suggests the presence of the human counterpart of this novel murine T-cell population.

Adolescent↗
PubMed1993

The effect of three dimensional collagen type I preparation on the structural organization of guinea pig enteric ganglia in culture.

In vivo, cellular relationships in the myenteric plexus are characterized by unusual compactness and by the arrangement of neurons and glia into ganglia and interconnecting strands. These features are lost when the myenteric plexus is placed in culture. In the present paper we test whether collagen type I, a major component of the matrix that surrounds the plexus in vivo, might have a role in maintaining normal neuron-glia relationships in this system. We report that a three-dimensional gel of rat tail collagen prevented the disaggregation of the guinea pig myenteric plexus in culture and induced the formation of a compact plexus-like cellular network when applied to disaggregated plexus cultures. These effects were not observed with soluble collagen. Immunohistochemical evidence was also obtained for synthesis of type I collagen by enteric glia. These observations indicate that type I collagen in a three-dimensional organization is capable of inducing and maintaining both the unusual compact organization of neurons and glial cells within myenteric ganglia and also the characteristic organization of these cells into an orderly network of ganglia and interconnecting strands.

Animals↗
PubMed1993

Effects of ciliary ganglionectomy on contractile responses in the dilator muscle of the rat iris.

Effects of removing the ciliary ganglion (CGR) on contractile responses of the rat iris dilator muscle to agonists were examined and compared with those after removing the superior cervical ganglion (SCGR). Denervations were considered successful if the atropine or phentolamine-sensitive mechanical responses to transmural nerve stimulation were abolished. After CGR, muscle sensitivity to noradrenaline (NA) increased two to three times in terms of their ED50, whereas the ED50 for methoxamine did not change. The sensitivity of both the control and denervated dilator muscles to NA increased after treatment with 30 microM cocaine, and resulted in similar ED50s. The content of NA in the whole iris decreased by about 27% after CGR. Maximal responses of the dilator muscle to NA and 5-hydroxytryptamine were significantly increased by CGR, but decreased by SCGR. These results indicate that sympathetic post-ganglionic nerves running through the CG and short ciliary nerves contribute about 27% of the total sympathetic innervation of the iris region. The CGR, therefore, induced a small presynaptic supersensitivity specific to NA. The non-specific increase in the maximal responses to agonists after CGR may be attributable to a parasympathetic denervation since sympathectomy by SCGR decreased the maximal responses.

Animals↗
PubMed1993

Production and characterization of antibodies to the beta-(1-->6)-galactotetraosyl group and their interaction with arabinogalactan-proteins.

Rabbit antisera were raised against beta-(1-->6)-galactotetraose coupled to bovine serum albumin (Gal4-BSA). The antisera reacted with arabinogalactan-proteins (AGPs) isolated from seeds, roots, or leaves of radish (Raphanus sativus L.) as revealed by immunodiffusion analysis. Extensive removal of alpha-L-arabinofuranosyl residues from these AGPs enhanced the formation of precipitin with the antisera. The antisera did not react with such other polysaccharides as soybean arabinan-4-galactan, beta-(1-->4)-galactan, and beta-(1-->3)-galactan, indicating their high specificity toward the consecutive beta-(1-->6)-galactosyl side chains of AGPs. The antibodies were purified by affinity chromatography on a column of immunobilized beta-(1-->6)-galactotetraose as ligand. The specificity of the antibodies toward consecutive (1-->6)-linked beta-galactosyl residues was confirmed by enzyme-linked immunosorbent assay for hapten inhibition against Gal4-BSA as antigen, which revealed that beta-(1-->6)-galactotriose and -tetraose were potent inhibitors, while beta-(1-->3)- or beta-(1-->4)-galactobioses and -trioses were essentially unreactive. Electron-microscopic observation of immunogold-stained tissues demonstrated that AGPs were localized in the middle lamella as well as at the plasma membrane of primary roots of radish. Agglutination of protoplasts prepared from cotyledons occurred with the antibodies, supporting the evidence for localization of AGPs in the plasma membrane. The antibody-mediated agglutination was inhibited by addition of AGPs or beta-(1-->6)-galactotetraose.

Agglutination↗
PubMed1993

Cloning and characterization of the glutamate 1-semialdehyde aminomutase gene from Xanthomonas campestris pv. phaseoli.

The gene from Xanthomonas campestris pv. phaseoli for glutamate 1-semialdehyde (GSA) aminomutase, which is involved in the C5 pathway for synthesis of delta-aminolevulinic acid (ALA), was cloned onto a multicopy plasmid, pUC18, by the complementation of an ALA-deficient mutant (hemL) of Escherichia coli. Subcloning of deletion fragments from the initial 3.5-kb chromosomal fragment allowed the isolation of a 1.7-kb fragment which could complement the hemL mutation. Nucleotide sequence analysis of the 1.7-kb DNA fragment revealed an open reading frame (ORF) that is located downstream from a potential promoter sequence and a ribosome-binding site. The ORF encodes a polypeptide of 429 amino acid residues, and the deduced molecular mass of this polypeptide is 45,043 Da. The amino acid sequence shows a high degree of homology to the HemL proteins from other organisms, and a putative binding site for pyridoxal 5'-phosphate is conserved.

Amino Acid Sequence↗
PubMed1993

Nonlinear mixed effect modeling of the pharmacodynamics of natriuretic peptides in rats.

Natriuretic peptides have not only natriuretic/diuretic but also hypotensive activities, and the decreased renal perfusion caused by the excessive hypotension is known to attenuate the diuretic actions. The present study was designed to examine the relationship between the dosing (intravenous constant infusion) rates and the diuretic actions of alpha-rat atrial natriuretic peptide (alpha-rANP) and rat brain natriuretic peptide (rBNP) in rats, and population (nonlinear mixed effect model) analysis was applied to these complicated diuretic actions. The intrinsic diuretic activities of alpha-rANP and rBNP could be analyzed, and the effects of blood pressure, heart rate, and also inhibition of degradation enzyme on the diuresis of natriuretic peptides were estimated simultaneously. The population analysis was useful for analyzing such pharmacodynamic data for which the individual analysis could not be applied easily.

Animals↗
PubMed1993

Molecular and cellular features of esophageal cancer cells.

More than 70 cell lines were established from esophageal cancer, including 15 TE-series cell lines established by the authors. This article reviews molecular and cellular features of esophageal cancer cells from studies using these cell lines as well as primary tumors. The subjects reviewed include primary cultures of normal epithelium of the esophagus and of esophageal tumors, their growth and differentiation properties, chromosomal aberrations, protein kinase C, growth factors and their receptors, oncogenes, and tumor-suppressor genes. Lesions of genetic loci in esophageal cancer include the absence of mutations in ras genes in primary tumors, amplification and overexpression of the c-erbB gene, co-amplification of hst-1 and int-2 genes, mutations, and allelic loss of tumor suppressor genes, p53, Rb, APC, and MCC. Future clinical improvement will be achieved on the basis of the understanding of molecular and cellular features of esophageal cancer cells.

Aged↗
PubMed1993

Simple, noninvasive system for measuring the heart rate of avian embryos and hatchlings by means of a piezoelectric film.

Using a flexible piezoelectric film, the authors developed a simple system to determine noninvasively the heart rate of chicken embryos and hatchlings. The film was piezoelectric polyvinylidene fluoride (PVDF), which is sensitive enough to detect cardiogenic ballistic movements of the egg (ballistocardiogram (BCG)) and precordial movements of the hatchling attributable to cardiac contractions (apexcardiogram (ACG)). The BCG could be detected, during the second half of incubation, by placing the egg on the PVDF film on a soft substrate. The detected signal was found to be a measure of movement velocity. The ACG could be measured when the hatchling's chest wall made contact with the PVDF film installed in a box in which the hatchling was confined. The heart rate was counted from the lag time of autocorrelation calculated for a certain time segment (e.g. 2 s) of the BCG and ACG recordings.

Animals↗
PubMed1993

Elevation of the extracellular glutamate concentration in the hippocampus after total cerebral ischemia related to the deterioration of the recovery in EEG and evoked potentials in dogs.

The concentrations of extracellular glutamate (Glu), aspartate (Asp) and glycine (Gly) were measured by microdialysis method in the cortex and hippocampus before, during and after 15 min of total cerebral ischemia in dogs. The correlations between the concentrations of amino acids and the changes in EEG and evoked potentials (EP) after ischemia were evaluated. Total cerebral ischemia was achieved by occluding the ascending aorta and the caval veins. The concentrations of Glu in the hippocampus significantly increased from 1.73 +/- 0.59 (mean +/- SEM) nmol.ml(-1) at pre-ischemia to 5.46 +/- 1.34 (P < 0.05) during ischemia and 14.37 +/- 3.70 (P < 0.01) 0-15 min after ischemia, and returned to the pre-ischemic level 30 min after ischemia. The concentration of hippocampal Glu 0-15 min after ischemia had significant negative correlations with the EEG-EP scores (0 = serious deterioration of electrical function and 6 = normal electrical function) 30 min, 3 hr and 5 hr after ischemia (r = -0.69, P < 0.05 : r = -0.67, P < 0.05 : r = -0.70, P < 0.05, respectively). The increase of the extracellular Glu concentration in the hippocampus immediately after ischemia may aggravate the neurological outcome after total cerebral ischemia.

Journal Article↗
PubMed1993

Periandrin V, a further sweet triterpene glycoside from Periandra dulcis.

A new sweet triterpene glycoside, periandrin V, was isolated from the roots of Periandra dulcis and identified as 3 beta-O-[beta-D-xylopyranosyl-(1-->2)-beta-D-glucuronopyranosyl]-25 -al-olean-18(19)-en-30-oic acid on the basis of chemical and spectral evidence. The structure of an acid-rearranged product of periandrin V and the parent compound, periandrin I, was determined as 1(10-->25) abeo-3 alpha, 25 alpha-epoxy-olean-5(10), 18-dien-30-oic acid methyl ester.

Carbohydrate Sequence↗
PubMed1993

Characterization of the T cells in aged rat bone marrow.

In this study, we determined the characteristics of CD3-positive (CD3+) T cells existing in rat bone marrow (BM). In contrast to splenic T cells, BM CD3+ T cells are composed of a higher proportion of CD8+ T cells, and the number of both cell types increased with age. Such CD3+ T cells in aged rats showed a similar usage of TCR V beta as splenic T cells, suggesting that BM CD3+ T cells are thymus-dependent and composed of an ordinary population in view of the expression of the TCR beta-chain. Purified T cells obtained from aged rat BM showed a markedly proliferative response by stimulation with immobilized anti-CD3 mAb, as did splenic T cells. However, the addition of BM non-T cells completely inhibited the response of both BM and splenic T cells in vitro. These results suggest that T cells in rat BM are negatively regulated by BM non-T cells in their response to the TCR-mediated signal not to disrupt the microenvironment of the BM.

Aging↗