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Biomedical subjects

H Toh

Publications and source records attributed to H Toh.

At least 19 recordsLinked to original sources
PubMed1992

Structural organization of the gene for prostaglandin D synthase in the rat brain.

A 3-kilobase-pair gene for rat brain prostaglandin D synthase [(5Z,13E)-(15S)-9 alpha,11 alpha-epidoxy-15-hydroxyprosta-5,13- dienoate D-isomerase, EC 5.3.99.2], which belongs to the lipocalin family, was isolated from a rat genomic DNA library by plaque hybridization with the cDNA for the enzyme. The gene contains seven exons, and all the splice donor and acceptor sites conform to the GT/AG rule. Transcription initiates at a guanine residue 39 base pairs upstream of the translation initiation codon, as determined by primer-extension analysis of rat brain mRNA. The 5'-flanking region of the gene lacks typical transcriptional regulatory sequences, such as TATA and CAAT boxes, but contains several sets of inverted repeats, direct repeats, and sequences resembling the transcriptional factor Sp1-binding site. The gene structure of prostaglandin D synthase is remarkably analogous to those of other lipocalins, such as beta-lactoglobulin, alpha 2-urinary globulin, placental protein 14, and alpha 1-microglobulin, in terms of number and sizes of exons and phase of splicing of introns. Furthermore, in a multiple alignment of the deduced amino acid sequences, positions of exon/intron junction of the prostaglandin D synthase gene are highly conserved and located around the positions of those of the genes for other lipocalins despite a weak homology.

Amino Acid Sequence↗
PubMed1992

Pilonidal sinus on the neck.

A recurrent nuchal abscess was treated in a 21-year-old obese young man with a total excision of the lesion. In the histopathological findings, many similarities were found between this lesion and pilonidal sinus. We discuss the pathogenesis of this lesion, as well as our belief that this case was a rare example of pilonidal sinus on the neck.

Adult↗
PubMed1992

Molecular evolution of cyclooxygenase and lipoxygenase.

Four oxygenases of the arachidonic acid cascade (cyclooxygenase, 5-lipoxygenase, 12-lipoxygenase and 15-lipoxygenase) were investigated by the method of computer-assisted sequence comparison. From the calculations, some aspects of evolution and function of these enzymes were revealed. (1) The evolutionary origin of cyclooxygenase was different from that of lipoxygenases. (2) Cyclooxygenase was a distantly related member of a peroxidase family. (3) Enzymes with 12-lipoxygenase activity were created independently twice by gene duplication.

Amino Acid Sequence↗
PubMed1992

Human long-chain acyl-CoA synthetase: structure and chromosomal location.

A complementary DNA clone encoding the entire human long-chain acyl-CoA synthetase was isolated and the total 698-amino acid sequence was deduced. The amino acid sequence of human long-chain acyl-CoA synthetase shows 84.9% identity to that of rat long-chain acyl-CoA synthetase. The nucleotide sequences of the protein coding regions between human and rat long-chain acyl-CoA synthetase mRNAs are highly conserved (85.6%), whereas those of the 3' untranslated regions are less conserved (72%). The location of the human long-chain acyl-CoA synthetase gene was identified on chromosome 4 by spot hybridization of flow-sorted chromosomes. Computer-assisted homology search revealed a significant similarity of the enzyme with the enzymes of the luciferase family. Based on this similarity, the structure of human long-chain acyl-CoA synthetase can be divided into five domains: the N-terminus, two domains similar to those in enzymes of the luciferase family, a long gap region between the similar domains and the C-terminus.

Amino Acid Sequence↗
PubMed1992

Molecular evolution of phosphoenolpyruvate carboxylase for C4 photosynthesis in maize: comparison of its cDNA sequence with a newly isolated cDNA encoding an isozyme involved in the anaplerotic function.

Molecular events associated with the evolution of an enzyme for C4 photosynthesis were investigated. In maize, at least three isozymes of phosphoenolpyruvate carboxylase [EC 4.1.1.31] are known: the C4-form, the C2-form and the root-form, being named according to their physiological roles and pattern of tissue distribution [Ting, I.P. & Osmond, C.B. (1973) Plant Physiol. 51, 448-453]. A cDNA clone which presumably encodes the C3-form isozyme was newly isolated and analyzed. Comparison of the sequences of the C3-form and C4-form isozymes revealed that (i) the homologies in the nucleotide and deduced amino acid sequences were 71 and 77%, respectively, and (ii) the gene for the C4-form isozyme evolved under strong G/C pressure. The genes for these isozymes were found to be located apart on different chromosomes. A phylogenetic tree was constructed using 8 amino acid sequences of phosphoenolpyruvate carboxylases from various sources. The topology of the tree indicated that, at least in monocots such as maize and sorghum, the genes for the C4-form and C3-form isozymes diverged from their common ancestral gene earlier than the monocot-dicot divergence (about 2 x 10(8) yr ago), though the divergence of maize (C4 plant) from wheat (C3 plant) is supposed to have occurred much later (6 x 10(7) yr ago).

Amino Acid Sequence↗
PubMed1992

Scanning electron microscopic study on the lingual papillae in the Manchurian chipmunk, Tamias sibiricus asiaticus.

The superfacial structures of the tongues in the Manchurian Chipmunk, Tamias sibiricus asiaticus, were observed by scanning electron microscope. The tongues were long, tapering, narrow and thick with a long apical free portion and a small lingual prominence in the posterior half. In this animal, three circumvallate papillae were present in an inverted triangle, a minority of conical papillae on the pharyngeal part and parallel large conical papillae on the lateral border. The fungiform papillae were scanty on the dorsal surface. These characters suggested this animal was more primitive than the others in rodents.

Animals↗
PubMed1992

Anatomical study of the accessory mental foramen and the distribution of its nerve.

We examined the range of the accessory mental foramen [AMF] and its accessory mental nerve in three Japanese cadavers. The diameters of the AMF were relatively small: 0.74 mm, 0.80 mm and 0.89 mm. The distances between the mental foramen and AMF were: 0.67 mm, 2.1 mm and 5.74 mm. The distribution of the accessory mental nerve was different in the three cases. These nerves communicated with the branches of the facial and buccal nerves.

Aged↗
PubMed1991

[Stress management of overseas Japanese in Kuwait].

Forty percent of the Japanese businessmen in overseas positions are working in developing countries. However, few reports on the mental health care for them have been published. The Japan Overseas Medical Fund and The Kuwait Japanese Association has promoted the Kuwait Japanese Clinic. I had an opportunity to work at this clinic and to study the environmental health of Japanese businessmen in Kuwait. I found that in Kuwait, Japanese businessmen had to adapt to climatic, religious, cultural, and historical differences. Therefore, I investigated the incidence of stress related diseases which are caused by these environmental differences. Stress diseases occurred in 15.7 percent of total cases frequently, and some of them were very severe. After my stay in Kuwait, I believe that the setting up of medical information networks between various countries to alleviate medical anxiety and a system whereby instructions in the differences of medical systems in various countries would be very beneficial.

Environmental Health↗
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↗