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Biomedical subjects

H Hayashi

Publications and source records attributed to H Hayashi.

At least 847 records · Page 47Linked to original sources
PubMed1994

Isolation and characterization of a neutrophil chemotactic factor from Tritrichomonas foetus organisms.

A neutrophil chemotactic factor (TfNCF) was isolated from the crude extract of Tritrichomonas foetus organisms by a combination of anion-exchange chromatography on DE52 and gel filtration on Sephacryl S200. TfNCF showed homogenicity by both PAGE and SDS-PAGE. The molecular weight of TfNCF was estimated to be 22 and 24 kDa, by Sephacryl S200 gel chromatography and by SDS-PAGE under reducing conditions. Immunization of TfNCF caused almost complete protection against T. foetus infection in mice. Western blot analysis probed with anti-TfNCF antibody showed that the epitopes on TfNCF were not commonly shared on the other components of T. foetus organisms nor other helminthous parasite-derived components. Furthermore, pre-incubation of neutrophils with antigens of other helminthous parasites or N-formylmethionyl-leucyl-phenylalanine did not affect the neutrophil chemotactic activity for TfNCF. These results suggest that TfNCF is a novel NCF consisting of unique epitopes for both antigenicity and neutrophil chemotactic activity. The role of NCF in the initiation of the immune response is discussed.

Animals↗
PubMed1994

Protonation state of the active-site Schiff base of aromatic amino acid aminotransferase: modulation by binding of ligands and implications for its role in catalysis.

The Schiff base formed between Lys258 of Escherichia coli aromatic amino acid aminotransferase (ArAT) and the coenzyme pyridoxal 5'-phosphate (PLP) has a pKa value of 6.65. The pH dependency of the kinetic parameters was consistent with a mechanism by which the enzymatic form with the nonprotonated Schiff base productively binds aspartate, phenylalanine, and tryptophan. The Schiff base pKa value rose by 1.7-2.1 unit on binding of substrate analogs, and this strongly suggested protonation of the Schiff base upon formation of the Michaelis complex with substrates. The protonated "internal" Schiff base in the Michaelis complex is supposed to be attacked by the deprotonated substrate amino group, and this explains excellently the mechanism of transaldimination to form the PLP-substrate Schiff base. Phenylpropionate and indolepropionate caused similar increases in the pKa value to maleate. [Arg292-->Ala] ArAT showed the same pKa value as the wild-type enzyme. Therefore, neutralization of Arg292 by omega-carboxylate of dicarboxylic ligands, which had been well documented in aspartate aminotransferase to increase the Schiff base pKa, has little effect on the protonation of the Schiff base in ArAT. Thus the structure of ArAT is deliberately organized so that the Schiff base pKa is effectively modulated by substrates having only one carboxylate group.

Base Sequence↗
PubMed1994

The amino acid sequence of a boar transition protein 3.

The boar transition protein 3 (TP3) was extracted with acid from the isolated late spermatid nuclei or directly from the testes, fractionated with trichloroacetic acid, and reduced and carboxymethylated (RCM-). RCM-TP3 from the nuclei was purified by HPLCs on Nucleosil 300 7C18 and Hitachi #3057, and that from the testes, by ion-exchange chromatography on CM-Sephadex C-25 and HPLCs on Nucleosil 300 7C18 and Chemcosorb 7C8. The two TP3 preparations were identical in acid-urea- and SDS-gel electrophoretic mobilities and amino acid composition. The primary structure of TP3 was determined by manual Edman degradation of the peptides obtained by lysyl endopeptidase-digestion or by alpha-chymotrypsin-digestion of RCM-TP3 from the testes, and by automated Edman degradation of it. Boar TP3 is a basic protein of 76 residues: H-AKVTEKSWQPQTTSTKRWKKRKTPSQPRSRGKVRKIYKKVKRPLHVCSRKKYSPKVITTSRRQKRAR RANKFETIP-OH, and it shows 27% homology with boar TP1. TP3 is composed of an N-terminal region (1-19) having two characteristic tryptophan residues (8 and 18) which is absent in the known TP1 group, and a C-terminal region (20-76) having a close resemblance to boar TP1.

Amino Acid Sequence↗
PubMed1994

Programmed cell death in response to alkyllysophospholipids in endothelial cells.

Addition of the alkyllysophospholipid ET16-OMe, a putative antitumor drug, to the culture medium of human vascular endothelial cells resulted in apoptotic cell death. The death was characterized as programmed cell death since the process was inhibited by the addition of an inhibitor of protein synthesis. The mechanism responsible for apoptosis induced by alkyllysophospholipid has unique characteristics, as compared to those of apoptosis induced by other antitumor drugs, since the drug caused fragmentation of dying cells and its effect could be overcome by the presence of a survival factor, namely, fibroblast growth factor.

Antineoplastic Agents↗
PubMed1994

Aspartate aminotransferase from a thermophilic formate-utilizing methanogen, Methanobacterium thermoformicicum strain SF-4: relation to serine and phosphoserine aminotransferases, but not to the aspartate aminotransferase family.

The primary structure of the aspartate aminotransferase (AspAT) of an archaebacterium, Methanobacterium thermoformicicum strain SF-4, has been determined by cloning and sequencing of the gene for the enzyme. The gene had a consensus promoter and a ribosome binding sequence of methanogens in the 5' untranslated region, followed by an open reading frame starting with ATG and terminating with TGA. The deduced amino acid sequence was identical with the partial amino acid sequences of the enzyme including the N-terminal sequence, and the deduced molecular weight of 41,684 was virtually identical to that reported earlier for this enzyme [Tanaka, T., Yamamoto, S., Taniguchi, M., Hayashi, H., Kuramitsu, S., Kagamiyama, H., & Oi, S. (1992) J. Biochem. 112, 811-815]. The gene was expressed in Escherichia coli by inserting it into an expression vector just downstream of the lacZ promoter, and this verified that the cloned gene really encodes the Methanobacterium AspAT. The primary structure of the Methanobacterium AspAT showed extremely low homology, 5%, with AspATs of eubacteria, eukaryotes, and a thermoacidophilic arachaebacterium, Sulfolobus solfataricus. On the other hand, the Methanobacterium AspAT showed remarkable amino acid sequence homology, 31.5%, with rat serine:pyruvate aminotransferase and, 13.5%, with E. coli phosphoserine aminotransferase. Thus, the Methanobacterium AspAT apparently belongs to subgroup IV of the aminotransferases [Mehta, P.K., Hale, T.I., & Christen, P. (1993) Eur. J. Biochem. 214, 549-561], but not to subgroup I, in which all the AspATs known so far are included.

Amino Acid Sequence↗
PubMed1994

Isolation and properties of a protein complex containing flagellar movement-initiating phosphoprotein from testes of a white salmon.

Phosphorylation of a tyrosine residue within a 15-kDa protein has been found to play a role in the initiation of flagellar movement of quiescent spermatozoa of the rainbow trout, Salmo gairdneri [Morisawa & Hayashi (1986) Biomed. Res. 6, 181-184; Hayashi et al. (1987) J. Biol. Chem. 262, 16692-16698]. In order to find a more accessible source of the 15-kDa protein for biochemical studies, phosphorylation of proteins was studied in other organs from other species. Cell-free extracts from spermatozoa and testes of Salmonidae were prepared and all catalyzed the cAMP-dependent, Mg(2+)-requiring, but Ca(2+)-independent phosphorylation of the 15-kDa proteins. Protein from the testes of a white salmon, Oncorhynchus keta, was isolated by conventional purification methods. The 15-kDa protein in the cell-free extract was found to be complexed with several other proteins such that the 15-kDa protein and its phosphorylating activity were copurified. Isolation of a sufficient amount of the complex for the preparation of antibodies against the various constituents is now possible.

Animals↗
PubMed1994

Monoclonal antibodies against the protein complex that contains the flagellar movement-initiating phosphoprotein of Oncorhynchus keta.

We isolated and characterized several monoclonal antibodies against a protein complex containing the flagellar movement-initiating phosphoprotein (MIPP) that appears to play a crucial role in the initiation of flagellar movement in quiescent spermatozoa of Salmonid fish. The effects of the antibodies on the phosphorylation of MIPP, as well as on the initiation of movement, in model sperm cells were studied. Three monoclonal antibodies, namely, FMI7, FMI18, and FMI27, were found specifically to inhibit both the initiation of flagellar movement and the phosphorylation of MIPP. These antibodies did not recognize denatured MIPP; they only recognized the native antigen. FMI7 exclusively recognized the denatured form of a 38-kDa protein, which may possibly be a protein kinase responsible for the phosphorylation of MIPP. Immunofluorescence analysis in situ of model sperm cells with the antibodies showed that the antigen was localized predominantly in the basal structure of the spermatozoon. Thus, the results clearly demonstrate the involvement of MIPP in the initiation of flagellar movement and the control of flagellar motility.

Animals↗
PubMed1994

Classification of signals for blocking apoptosis in vascular endothelial cells.

The survival and death of human umbilical vascular endothelial cells in culture are affected by several factors, such as fibroblast growth factor (FGF), serum, phorbol ester (TPA), and vanadate. In order to identify common aspects of the various signal-transduction processes during the course of apoptotic or programmed cell death, we designed experiments to distinguish between these factors in terms of the pathway that is responsible for the processing of each stimulus. We found, for example, that the effect of removal of FGF was specifically overcome by the addition of the phorbol ester. Our results indicated that two distinct pathways were operative, one specific for signal transduction initiated by FGF and phorbol ester and another specific for signal transduction initiated by serum and vanadate. These two pathways merged down-stream of the individual signal-processing pathways.

Apoptosis↗
PubMed1994

X-ray crystallographic study of pyridoxamine 5'-phosphate-type aspartate aminotransferases from Escherichia coli in three forms.

The three-dimensional structures of pyridoxamine 5'-phosphate-type aspartate aminotransferase from Escherichia coli and its complexes with maleate and glutarate have been determined by X-ray crystallography at 2.2, 2.1, and 2.7 A resolution, respectively. The enzyme is a dimeric form comprising two identical subunits, each of which is divided into one large and one small domain. The complex with maleate showed that substrate (or inhibitor) binding induced a large conformational change from the "open" to the "closed" form, resulting in closure of the active site by the small domain movement, as was observed in the pyridoxal 5'-phosphate-type enzyme. In the open form, three hydrophobic residues (hydrophobic plug) at the entrance of the active site are exposed to solvent. Maleate binding make the active site more hydrophobic by charge compensation and release of water molecules, facilitating the movement of the hydrophobic plug into the active site pocket to induce a large conformational change in the enzyme. Maleate is fixed rigidly in the active site pocket by extensive salt bridges and a hydrogen bonding network, guaranteeing the stereo-specificity of the catalysis and giving a Michaelis complex model. Contrary to our expectation, the glutarate complex was in the open form, suggesting that the equilibrium between the open and closed forms lies far toward the open form in solution. The water molecules located in the active site pocket were almost completely conserved between Escherichia coli and chicken mitochondrial aspartate aminotransferase with the same type of cofactor and the same conformation.

Aspartate Aminotransferases↗
PubMed1994

Nasal reconstruction using free temporoparietal fascial flap transfer (Upton's method).

Reconstructive surgery for severe nasal deformity after radical operation of the maxillary antrum was performed by free temporoparietal fascia transfer to the nasal membrane, followed by secondary-rib cartilage grafting. Correction of nasal deformity caused by severe scar contracture and tissue defect in the nasal cavity has been considered difficult. However, skin grafting with temporoparietal fascia transfer to the nasal membrane can make it possible to perform cartilage grafting without exposure. This method should be nominated as a useful procedure for correction of severe nasal deformity caused by nasal membranous scar contracture.

Female↗
PubMed1994

Immunohistochemical study of cellular fibronectin in preretinal membranes.

BACKGROUND: The presence of fibronectin has been shown in preretinal membranes from eyes with proliferative vitreoretinopathy and proliferative diabetic retinopathy. It is not clear, however, which type of fibronectin (plasma or cellular) is present in preretinal membranes. METHODS: A human cellular fibronectin antibody was used to immunohistochemically determine if cellular fibronectin only demonstrates presence or association with proliferation of preretinal membranes. RESULTS: The results revealed a diffuse distribution of cellular fibronectin within membranes extracted from proliferative vitreoretinopathy and proliferative diabetic retinopathy patients, and a localized distribution of neovascular vessels in proliferative diabetic retinopathy membranes. CONCLUSION: Cellular fibronectin produced locally in preretinal membranes may contribute a local, cell-mediated process to cell proliferation or migration and the expression of cellular fibronectin by the cellular constituents of preretinal membranes is unique to this pathologic situation like proliferative diabetic retinopathy and proliferative vitreoretinopathy.

Adult↗
PubMed1994

Photosynthetic oxygen evolution is stabilized by cytochrome c550 against heat inactivation in Synechococcus sp. PCC 7002.

We investigated the factors responsible for the heat stability of photosynthetic oxygen evolution by examining thylakoid membranes from the cyanobacterium Synechococcus sp. PCC 7002. We found that treatment of the thylakoid membranes with 0.1% Triton X-100 resulted in a remarkable decrease in the heat stability of oxygen evolution, and that the heat stability could be restored by reconstituting the membranes with the components that had been extracted by Triton X-100. The protein responsible for the restoration of heat stability was purified from the Triton X-100 extract by two successive steps of chromatography. The purified protein had a molecular mass of 16 kD and exhibited the spectrophotometric properties of a c-type Cyt with a low redox potential. The dithionite-minus-ascorbate difference spectrum revealed an alpha band maximum at 551 nm. We were able to clone and sequence the gene encoding this Cyt from Synechococcus sp. PCC 7002, based on the partial amino-terminal amino acid sequence. The deduced amino acid sequence revealed a gene product consisting of a 34-residue transit peptide and a mature protein of 136 residues. The mature protein is homologous to Cyt c550, a Cyt with a low redox potential. Thus, our results indicate that Cyt c550 greatly affects the heat stability of oxygen evolution.

Amino Acid Sequence↗
PubMed1994

The rice culture filtrate of Bacillus cereus isolated from emetic-type food poisoning causes mitochondrial swelling in a HEp-2 cell.

Rice culture filtrates of Bacillus cereus SA-50, an emetic-type strain, produced a toxin which caused cytoplasmic vacuole formation in HEp-2 and HeLa cells. Electron microscopic observation revealed that the apparent vacuoles in HEp-2 seen under a light microscope were actually swollen mitochondria. The oxygen consumption of HEp-2 cells was accelerated by the addition of the rice culture filtrate as was measured with a polarographic oxymeter; a respiratory control ratio was 1.0 for control cells, while 1.4 for ones with the filtrates. The culture filtrates showed a similar effect on the isolated mouse liver mitochondria; respiratory control ratios for the mitochondria with and without the filtrates were 3.6 and 1.0, respectively. The affecting manner of the culture filtrates on the oxygen consumption of mitochondria was similar to that of 2,4-dinitrophenol, suggesting that the culture filtrate contains a toxin acting as an uncoupler of oxidative phosphorylation in mitochondria. It is likely that the culture filtrates containing the emetic toxin of B. cereus causes mitochondrial swelling with a close relationship to the uncoupling of the oxidative phosphorylation of mitochondria.

Animals↗
PubMed1994

Disaccharide analysis of the skin glycosaminoglycans in patients with Werner's syndrome.

The disaccharide content of the chondroitinase-digestible glycosaminoglycans (GAGs) extracted from 6-mm skin punch biopsies from the atrophic and sclerotic skin of two patients with Werner's syndrome (WS) were determined using high-performance liquid chromatography after 1-phenyl-3-methyl-5-pyrazolone labelling. The total amount of main disaccharides was significantly decreased in the atrophic lesions of WS. In the atrophic forearm skin, the decrease in the main disaccharide unit of hyaluronic acid, delta Di-HA, and the increase in the ratio of the main disaccharide unit of dermatan sulphate, delta Di-4S, to delta Di-HA were significant vs. normal control (P < 0.01 and 0.05, respectively). The sclerotic skin showed an increase in delta Di-4S (DS) (P < 0.05) and a decrease in delta Di-HA (P < 0.02) compared with normal controls, as well as a significantly higher ratio of delta Di-4S (DS)/delta Di-HA compared with normal controls (P < 0.0002) and systemic sclerosis patients (SSc; P < 0.02). No other statistical difference was found in the amount of each main disaccharide unit between the sclerotic skin of WS and SSc. Histological examination revealed that the atrophic skin showed thinning of the dermis with a slight increase of fine collagen bundles, whereas the sclerotic skin demonstrated a thickened dermis with prominent deposition of fine collagen bundles in the deep dermis. In SSc, thickening of the whole dermis, composed of hyalinized or swollen collagen bundles, was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Pharmacological profiles of the subtypes of muscarinic cholinoceptors that mediate aggregation of pigment in the melanophores of two species of catfish.

Using selective antagonists, including pirenzepine, adiphenine, AF-DX 116, gallamine, and 4-DAMP, we attempted to characterize the muscarinic cholinoceptors on the melanophores of the translucent glass catfish Kryptopterus bicirrhis and the mailed catfish Corydoras paleatus. The M3 receptor-selective antagonist, 4-DAMP, potently inhibited the acetylcholine-induced aggregation of pigment in both species. It appeared, therefore, that the receptors that mediated the cholinergically evoked aggregation of melanosomes in these species were of the M3 muscarinic subtype.

Acetylcholine↗
PubMed1994

Effects of intracellular pH on calcium currents and intracellular calcium ions in the smooth muscle of rabbit portal vein.

In smooth muscle cells freshly dispersed from the rabbit portal vein, effects of intracellular pH (pHi) on Ca2+ channel currents were studied with the whole-cell clamp method using nystatin in the pipette. pHi was modified with ammonium chloride (NH4Cl) and propionate. Changes in intracellular Ca2+ concentration ([Ca2+]i) and pHi were also measured with the fluorescent indicator fura-2 and a pH-sensitive dye, respectively, together with the mechanical response in intact tissues. Intracellular alkalinization caused by an application of NH4Cl (20 mM) markedly potentiated and acidification caused by propionate (20 mM) inhibited inward Ca2+ channel currents, without much change in the kinetics. Tension development induced by 60 mM K- was inhibited by NH4Cl (20 mM) and potentiated by propionate (20 mM), whereas the peak [Ca2+]i level reached during K+ contracture was reduced in the presence of NH4Cl and increased in the presence of propionate. It was concluded that the modification of Ca2+ channel currents caused by pHi is not directly related to the effects of pHi on the mechanical response to excess K+. The direct effects of pHi on [Ca2+]i and on contractile machinery are considered to be mainly responsible for the mechanical effect of pHi.

Ammonium Chloride↗
PubMed1994

Protein binding of human immunodeficiency virus protease inhibitor KNI-272 and alteration of its in vitro antiretroviral activity in the presence of high concentrations of proteins.

KNI-272 represents a peptide-based protease inhibitor having potent antiretroviral activity against human immunodeficiency virus (HIV) in vitro. The structure contains allophenylnorstatine [(2S,3S)-3-amino-2-hydroxy-4-phenylbutyric acid] with a hydroxymethylcarbonyl isostere. We asked whether this experimental anti-HIV agent could exert its activity in vitro in the presence of relatively high concentrations of fetal calf serum (FCS) and assessed its protein-binding properties by using fresh human plasma preparations. The 50 and 75% inhibitory concentrations of KNI-272 against HIV type 1 replication in vitro were 3- to 5-fold and 5-fold higher in the presence of 50% FCS and 15- to 25-fold and 25- to 100-fold higher in the presence of 80% ECS, respectively, than those with 15% FCS, whereas the antiviral activity of 2',3'-dideoxyinosine was not significantly affected by FCS concentrations in the culture. Detailed studies of the protein binding of KNI-272 suggest that in human plasma binding occurs predominantly to alpha 1-acid glycoprotein and that KNI-272 is probably extensively (approximately 98 to 99%) protein bound at concentrations likely to be achieved in the circulation. Thus, higher levels of KNI-272 in plasma may be required when this compound undergoes clinical trials relative to those inferred from in vitro data involving the use of 10 to 15% FCS-containing culture media. The current data may have a relevance to other antiretroviral drugs that are under development and that have a high protein-binding capacity.

Animals↗