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Biomedical subjects

H Toh

Publications and source records attributed to H Toh.

At least 91 records · Page 5Linked to original sources
PubMed1991

Human brain prostaglandin D synthase has been evolutionarily differentiated from lipophilic-ligand carrier proteins.

cDNAs for glutathione-independent prostaglandin D synthase were isolated from cDNA libraries of human brain. The longest cDNA insert was 837 base pairs long and contained a coding region of 570 base pairs corresponding to 190 amino acid residues with a calculated Mr of 21,016. Between two cDNA inserts isolated from the two different libraries, nucleotide substitutions were observed at 16 positions, including conservative amino acid substitutions at 2 positions and nonconservative substitutions at 5 positions, indicating genetic heterogeneity of this enzyme in humans. The computer-assisted homology search revealed that the enzyme is a member of the lipocalin superfamily, comprising secretory hydrophobic molecule transporters, showing the greatest homology (28.8-29.4% identity; 51.3-53.1% similarity) to alpha 1-microglobulin among the members of this superfamily. In a phylogenetic tree of the superfamily, this enzyme, alpha 1-microglobulin, and the gamma chain of the complement component C8 form a cluster separate from the other 14 members. The two distinctive characteristics of glutathione-independent prostaglandin D synthase, as compared to the other members of this superfamily, are its enzymatic properties and its association with membranes that were probably acquired after evolutionary divergence of the two lipocalins. Based on the observed sequence homology, the tertiary structure of the enzyme was deduced to consist of an eight-stranded anti-parallel beta-barrel forming a hydrophobic pocket. Furthermore, the Cys-65 residue in the pocket, which is conserved only in the human and rat enzymes but not in other lipocalins, was considered to be a putative active site of the enzyme.

Amino Acid Sequence↗
PubMed1991

Cloning by functional expression of platelet-activating factor receptor from guinea-pig lung.

Platelet-activating factor (PAF), a unique phospholipid mediator, possesses potent proinflammatory, smooth-muscle contractile and hypotensive activities, and appears to be crucial in the pathogenesis of bronchial asthma and in the lethality of endotoxin and anaphylactic shock. Despite this, little is known of the molecular properties of the PAF receptor and related signal transduction systems. Although several lines of evidence suggest that activation of the PAF receptor stimulates phospholipase C and subsequent inositol trisphosphate formation through G protein(s), the PAF receptor and calcium channel are reported to show a close relation. As a first approach to cloning lipid autacoid receptors, we have isolated complementary DNA for the PAF receptors. Our strategy involved gene expression in Xenopus laevis oocytes and electrophysiological detection of PAF-induced responses. Sequence analysis indicates that the receptor belongs to the superfamily of G protein-coupled receptors.

Amino Acid Sequence↗
PubMed1991

Escherichia coli DNA polymerase II is homologous to alpha-like DNA polymerases.

The Escherichia coli polB gene encodes DNA polymerase II and is regulated by the SOS system. We sequenced a 4081 nucleotide segment of the E. coli chromosome that contains the polB gene and its flanking regions. DNA polymerase II, as deduced from the DNA sequence, consists of 782 amino acids, has a molecular weight of 89,917, and is structurally homologous to alpha-like DNA polymerases, which include eukaryotic replicative DNA polymerases. Comparison of the sequences of the alpha-like DNA polymerases including E. coli DNA polymerase II showed that there were nine highly conserved regions, and we constructed an unrooted phylogenetic tree of the DNA polymerases based on the differences in these conserved regions. The DNA polymerases of herpes groups viruses and the DNA polymerases that use protein priming for the initiation of replication form two separate subfamilies that occupy opposite locations in the tree. Other DNA polymerases, including E. coli DNA polymerase II, human DNA polymerase alpha, and yeast DNA polymerase I, occupy the central regions between the two subfamilies and they are rather distantly related to each other. The transcription initiation site of polB was identified by analysis of in vivo transcripts, and the promoter was assigned upstream of the polB coding region. The recognition sequence of the LexA repressor (SOS box) was identified by a footprinting experiment. It overlaps the -35 sequence of the polB promoter.

Amino Acid Sequence↗
PubMed1991

The anti Mac-1 monoclonal antibody inhibits neutrophil sequestration in lung and liver in a septic murine model.

We investigated the mechanism by which leukocytes adhere to the pulmonary and liver microvascular endothelium in a septic murine model. After C57BL/6 mice were intraperitoneally (ip) injected with lipopolysaccharide (LPS), a striking peripheral leukocytopenia occurred as neutrophils accumulated rapidly in the lung and liver. When the anti-Mac-1 monoclonal antibody (mAb) was administered intravenously (iv) 2 hr before the ip administrated LPS, leukocytopenia and neutrophil accumulation in the lung and liver were inhibited significantly at 3 hr after the LPS injection. An immunofluorescence study revealed that Mac-1 expression on leukocytes from LPS-injected mice were greatly increased when compared to that of controls. Additionally, an in vitro assay demonstrated that LPS-activated serum increased neutrophil Mac-1 expression and neutrophil adhesion to the endothelial monolayer and that these phenomena are inhibited by pretreatment of neutrophils with anti-Mac-1 mAb. These results indicate that a marked increase in Mac-1 antigen expression by leukocytes plays a crucial role in striking neutrophil attachment to the vascular endothelium and is likely to be the cause of neutrophil accumulation in the lung and liver during endotoxemia.

Animals↗
PubMed1991

Morphological studies of the foramen caecum linguae of the human and guinea pig tongue.

A three-dimensional study of the development of the thyroid gland in human and guinea pig embryos was made together with a histological investigation of the foramen caecum of the human adult tongue. In the human embryo, an epithelial depression was not seen between the first and second branchial arches except a shallow sulcus. Ciliated cells were observed on the dorsal surface of the tongue in all embryos which exceeded 18 mm in crown-rump length. The presence of a foramen caecum was observed in 18 (51%) cadavers from 35 human adults. Several circumvallate papillae were found in a 10-mm-deep foramen caecum on the side adjacent to the anterior two thirds of the tongue. In all specimens serous glands open into the foramen caecum.

Animals↗
PubMed1991

Sequence analysis of firefly luciferase family reveals a conservative sequence motif.

A conservative sequence motif was extracted from an alignment of the firefly luciferase family. AngR derived from a pathogenic bacterium and acetyl-CoA synthetases derived from two ascomycete fungi were identified as members of the firefly luciferase family by a homology search with the motif and other sequence comparison analyses. The motif sequence shares several characteristics with the phosphate-binding sites of phosphoproteins and nucleotide-binding proteins. A multiple alignment and an unrooted phylogenetic tree were constructed for the investigation of evolutionary relationships within the firefly luciferase family.

Amino Acid Sequence↗
PubMed1990

Leukotriene A4 hydrolase is a zinc-containing aminopeptidase.

A comparison of amino acid sequences revealed that leukotriene A4 (LTA4) hydrolase is homologous to various types of aminopeptidases. Consistently with the finding, the purified LTA4 hydrolases from both human and guinea pig sources contained equimolar zinc ion, as determined by atomic absorption spectrometry. The enzyme had a significant amount of aminopeptidase activity toward synthetic peptide substrates. Both LTA4 hydrolase and aminopeptidase activities were inhibited by o-phenanthroline, p-chloromercuribenzoic acid, and Leu-thiol with similar IC50 values. Co-purification as well as co-immunoprecipitation of both enzyme activities with an affinity-purified antibody against LTA4 hydrolase strongly suggest that the two enzyme activities reside in a single protein.

Aminopeptidases↗
PubMed1990

Molecular cloning and expression of human arachidonate 12-lipoxygenase.

The cDNA for a 12-lipoxygenase was isolated from cDNA library of human erythroleukemia cells. The cDNA had an open reading frame encoding 663 amino acids with a calculated molecular weight of 75,513. The deduced amino acid sequence of human 12-lipoxygenase exhibited 41.5%, 65.3% and 65.4% identity with human 5-lipoxygenase, human 15-lipoxygenase and porcine 12-lipoxygenase, respectively. Blot hybridization analysis of RNA from human erythroleukemia cells demonstrated a single species (3.1 kb) of mRNA with the cDNA probe for 12-lipoxygenase of these cells, but not with the cDNA for porcine leukocyte enzyme. The cytosol of Escherichia coli transformed with a recombinant pUC19 plasmid oxygenated the position 12 of arachidonic acid.

Amino Acid Sequence↗
PubMed1990

Molecular evolution and zinc ion binding motif of leukotriene A4 hydrolase.

Leukotriene A4 (LTA4) hydrolase belongs to the aminopeptidase N family. In order to investigate the molecular evolution and physiological significance of LTA4 hydrolase, the enzymes belonging to the family were aligned and a phylogenetic tree was constructed. From the alignment, it was found that three residues involved in zinc binding and one residue of the active sites of aminopeptidases N were conserved in LTA4 hydrolase. In agreement with the observation, LTA4 hydrolase is a zinc protein as determined by atomic absorption spectroscopy.

Amino Acid Sequence↗
PubMed1990

Horseshoe kidney found in a female cadaver.

The present report describes a case of malformation of the kidney, of the type known as horseshoe kidney, in an 83-year-old Japanese female used for student dissection practice. In this case, the kidney consisted of three parts: the original kidneys on both sides and an isthmus between them. The kidneys formed a U-shaped structure as a result of fusion at the inferior poles of the original kidneys. As a whole, the structure presented a typical horseshoe shape. The renal artery system as well as the position of the kidney was almost normal except for a surplus artery into the isthmus. The incidence of horseshoe kidney was estimated to be 0.27% in our department for the period from 1975 to 1988.

Aged↗
PubMed1990

N-terminal halves of gramicidin S synthetase 1, and tyrocidine synthetase 1 as novel members of firefly luciferase family.

It was found, by computer-assisted homology search, that the N-terminal halves of gramicidin S synthetase 1 and tyrocidine synthetase 1 are homologous with beetle luciferases and plant 4-coumarate:CoA ligases. The comparison of the reactions catalyzed by these enzymes showed that they are involved in similar reactions; the adenylation of their substrates and the formation of thiolester. Structural and functional implication of the sequence homology and molecular evolution of these proteins are discussed.

Amino Acid Isomerases↗
PubMed1989

Prostaglandin endoperoxide synthase contains an EGF-like domain.

Prostaglandin endoperoxide synthase was subjected to the computer-assisted homology search in the protein primary structure database, in order to investigate the regulation mechanism of the expression of prostaglandin endoperoxide synthase. As a result of that, it turned out that prostaglandin endoperoxide synthase shares sequence homology with epidermal growth factor (EGF) in the N-terminal region. The implication of the existence of an EGF-like domain in prostaglandin endoperoxide synthase is discussed.

Amino Acid Sequence↗
PubMed1989

Whether Zn2+ for the polymerase system was selected inevitably or by historical accident.

Zinc ion was found in various kinds of polymerases and involved in the activation of the 3'-hydroxyl group of primer chain's growing end. In order to investigate whether zinc ion was selected for nucleotide synthesizing system inevitably or by historical accident, ab initio molecular orbital calculations were carried out and the results suggest that zinc ion may have been selected inevitably.

Biological Evolution↗
PubMed1989

[Anomalous case of the left common carotid artery arising from the brachiocephalic trunk].

We found an anomalous branch of the aortic arch during the students' dissection practice at Fukuoka Dental College in 1988. The results are as follows; This case was found in a 92-year-old female cadaver (cause of death: cardiac dissufficiency), whose brachiocephalic trunk arose from the aortic arch forming a striking trunk with the left common carotid artery. The diameter of this trunk was 17.2 mm at its origin and the longitudinal length was 11.0 mm. This case corresponded to Typus B of Adachi's classification, while to Type C of De Garis's.

Aged↗
PubMed1989

[The dental anthropological study on the erupted mesiodens in the Paiwan tribe of Formosan aborigines].

Mesiodens is one supernumerary tooth which appears in upper intra-central incisors. This tooth was originally described by Bolk (1917) who proposed the term 'mesiodens'. We investigated the incidence of mesiodens for the Paiwan tribe of Formosan aborigines (9 tribes) living in the mountain area of Taiwan. We have been continued to research on these tribes as viewed from dental anthropology. The materials used in this study were plaster casts of 152 males and 238 females (dental age: IIIA or over). The samples of the Paiwan tribe were selected from the dental casts obtained at Taitung and Pingtung (Machia and Wutai) in southern Taiwan. The results were as follows: 1. The occurrence of the erupted mesiodens in the upper incisal region was five cases (3.3%) in males, but was none in females. This tendency of incidence was much the same as that of Japanese. 2. The mesiodens was of rudimentary form: four cases (80%) showed conical-shaped type and the rest case was the sort of incisor. 3. In the incidence of the erupted mesiodens, the Paiwan tribe showed significantly higher than Japanese.

Anthropology↗