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H Horiuchi

Publications and source records attributed to H Horiuchi.

At least 145 records · Page 8Linked to original sources
PubMed1994

Identification of the bphA and bphB genes of Pseudomonas sp. strains KKS102 involved in degradation of biphenyl and polychlorinated biphenyls.

The nucleotide sequence of the upstream region of the bphC gene from Pseudomonas sp. strain KKS102 was determined. Four genes were found in this region. Deduced amino acid sequences of the first, second, third and fourth genes showed significant homology with a large subunit of iron-sulfur protein, a small subunit of iron-sulfur protein, ferredoxin and dihydrodiol dehydrogenase, respectively, from other bacteria which degrade biphenyl/polychlorinated biphenyls, toluene and benzene. E. coli, in which the four genes, bphC and the gene for ferredoxin reductase from benzene degrading bacterium were expressed, was able to produce meta-cleavage compounds from chlorinated biphenyls. These results show that these gene products are functional in both biphenyl and polychlorinated biphenyls degradation.

Alcohol Oxidoreductases↗
PubMed1994

The prosequence of Rhizopus niveus aspartic proteinase-I supports correct folding and secretion of its mature part in Saccharomyces cerevisiae.

Extracellular Rhizopus niveus aspartic proteinase-I (RNAP-I) was secreted effectively by Saccharomyces cerevisiae when RNAP-I with its preprosequence was synthesized in this organism (Horiuchi, H., Ashikari, T., Amachi, T., Yoshizumi, H., Takagi, M., and Yano, K. (1990) Agric. Biol. Chem. 54, 1771-1779). Certain deletions (delta pro, delta 1, delta 2), and amino acid substitutions (M1) in the prosequence blocked secretion of RNAP-I, although the protease protection assay revealed that even delta pro could be translocated across the membrane of the endoplasmic reticulum. When delta pro or M1 was synthesized simultaneously with the wild-type preprosequence in S. cerevisiae, secretion of RNAP-I was recovered. Therefore, the physical linkage of the prosequence to the mature region is not a prerequisite for secretion of active RNAP-I. Purified RNAP-I with the prosequence once denatured in 6 M guanidine HCl could be renatured and activated to have its enzymatic activity by removing guanidine HCl in vitro, but RNAP-I without the prosequence could not. Furthermore, the wild-type prosequence helped the recovery of the activity of the denatured RNAP-I in trans, but the prosequences of M1 with which secretion of RNAP-I was not observed in vivo, did not. From these results we concluded that the prosequence of RNAP-I supports correct folding of RNAP-I in the endoplasmic reticulum lumen and its subsequent secretion in S. cerevisiae. The functional role of the prosequence of an aspartic proteinase was elucidated.

Amino Acid Sequence↗
PubMed1994

Membrane association of Rab5 mediated by GDP-dissociation inhibitor and accompanied by GDP/GTP exchange.

The Rab GTPases function as specific regulators of membrane transport. The GTP/GDP cycle is believed to control shuttling of Rab proteins between the cytosol and organelle membranes. In vitro, Rab proteins are removed from membranes by a protein that inhibits GDP dissociation (rabGDI), which leads to formation of a cytosolic complex of Rab with the inhibitor protein. Here we use a purified Rab5-rabGDI complex in a permeabilized cell system to investigate how the cytosolic complexed form of Rab reassociates with the membrane. We find that exogenous Rab5 is correctly targeted and induces the formation of enlarged early endosomes, demonstrating that it is functionally active. Binding of Rab5 to the acceptor membrane is accompanied by release of the rabGDI protein into the cytosol. A transient GDP-Rab5 intermediate was detected which was subsequently converted into the GTP-bound form. Our results indicate that there is a multistep mechanism for the insertion of Rab5 into the membrane which is mediated by a guanine-nucleotide-exchange factor.

Animals↗
PubMed1994

Cloning and characterization of two 3-phosphoglycerate kinase genes of Rhizopus niveus and heterologous gene expression using their promoters.

Two 3-phosphoglycerate kinase genes (pgk1 and pgk2) were cloned from Rhizopus niveus. It was deduced that both pgk genes have two introns. They have open reading frames of 1,355 bp and 1,356 bp, and code for proteins of 417 and 416 amino acids, respectively. The first introns of both genes are located at similar positions as those of pgk genes from other fungi based on the deduced amino-acid sequences of PGK proteins. The position of their second introns was similar to that of the seventh intron of the human pgk gene. The deduced amino-acid sequences of PGK proteins show high identity (64.8-72.2%) to those of PGKs of other filamentous fungi. When the promoters of each of the pgk genes were fused to the E. coli beta-glucuronidase (GUS) gene and introduced into R. niveus, significant GUS activities were detected in the cell lysates of the transformants, suggesting that GUS protein was expressed under the control of both pgk gene promoters in R. niveus. GUS activity was induced by glucose but not by glycerol, indicating that expression of R. niveus pgk genes was regulated by the carbon source.

Bacterial Proteins↗
PubMed1994

Optical characteristics of human extracted teeth and the possible application of photoplethysmography to the human pulp.

In order to record pulp blood flow by photoplethysmography, the light transmission properties of extracted human teeth and human peripheral blood at wavelengths between 400 and 800 nm were first investigated. Transmission through peripheral blood and extracted teeth was lower at wavelengths shorter than 600 nm. Transmitted-light photoplethysmography (TLP) was applied to teeth in situ using a tungsten light, or one of two light-emitting diodes (LED) with peak wavelengths of 565 and 695 nm. A CdS-CdSe photoconductive cell was used as a detector. The LED with a peak intensity at 565 nm was the most efficient of the three light sources for recording the TLP. The results indicate that the TLP could be used to assess pulp vitality.

Adult↗
PubMed1994

pH profile of kinetic constants of RNase Rh from Rhizopus niveus and its mutant enzymes towards UpU, and possible mechanisms of RNase Rh.

In order to elucidate the mechanism of action of Rhizopus niveus RNase Rh, we investigated the pH profiles of the kinetic parameters of RNase RNAP Rh, a derivative of RNase Rh, and its mutant enzymes, i.e., RNase RNAP Rh H104F, RNase RNAP Rh E105Q, and RNase RNAP Rh D51N. Based on comparisons of their profiles we concluded that protonation of His104 is indispensable for the enzymatic activity and Glu105 accelerates the enzymatic activity, especially at acid pH centered at pH 3.5. Based on these data and the previous data on the chemical modification and enzymatic properties of other mutant enzymes, we propose the following as a possible mechanisms of RNase Rh action. (i) His109 participates in enzymatic action as a general base catalyst which removes the hydrogen of the 2'-OH of the ribose moiety. (ii) His46 participates in the reaction as a general acid catalyst which interacts with the 5'-oxygen atom of the scissile phosphodiester bond and becomes a proton donor to the departing nucleoside or nucleotide. (iii) His104 interacts with phosphate anion and its protonation is favorable for the enzymatic activity. (iv) Since the protonated form of Glu105 is more favorable for activity, we postulate two possible roles for Glu105: (a) its stabilizes the intermediate, and (b) it interacts with the oxygen atom of P = O and polarizes the phosphorus atom.

Dinucleoside Phosphates↗
PubMed1994

Giant cell tumor of the lung: an autopsy case report with immunohistochemical observations.

Tumors resembling giant cell tumor (GCT) of bone are well known to occur in other organs and many cases have been reported to date. While GCT occurring as primary lesions in the lung are extremely rare, the authors experienced such a tumor at an autopsy of a 77 year old woman and subsequently performed histological and immunohistochemical examinations. The clinical and morphologic characteristics of this case are documented, and the literature concerning this type of tumor is reviewed. The present tumor of the lung was histologically characterized by proliferation of benign-looking osteoclast-like giant cells in association with slightly atypical mononuclear cells. The tumor cells were immunohistochemically positive for histiocytic markers but negative for epithelial markers. This case appears to be the first reported benign giant cell tumor of the lung in which histiocytic differentiation of mononuclear cells was suggested by immunohistochemistry.

Aged↗
PubMed1994

Isolation and characterization of two chitin synthase genes of Rhizopus oligosporus.

Two chitin synthase genes (chs1 and chs2) were isolated from Rhizopus oligosporus by plaque hybridization probed with the chitin synthase 2 gene of Saccharomyces cerevisiae. From their deduced amino acid sequences, they were both class II chitin synthases according to the classification proposed by Bowen et al. The expression of these genes was controlled differently in each stage of differentiation. It was suggested that the gene products of chs1 and chs2 function mainly in the hyphae growing stage but not in the late stage of spore formation. When each of these genes was expressed in S. cerevisiae, elevation of chitin synthase activity was observed in both cases.

Amino Acid Sequence↗
PubMed1994

Isolation and characterization of two chitin synthase genes from Aspergillus nidulans.

Two chitin synthase genes, designated chsA and chsB, were isolated from Aspergillus nidulans with the Saccharomyces cerevisiae CHS2 gene as the hybridization probe. Nucleotide sequencing showed that chsA and chsB encoded polypeptides consisting of 1013 and 916 amino acid residues, respectively; the hydropathy profiles of the enzymes were similar to those of other fungal chitin synthases. Northern analysis indicated that both genes were transcribed, suggesting that cellular chitin in A. nidulans is synthesized by at least two chitin synthases. For examination of the roles of the chitin synthase genes in cell growth, gene disruption experiments were done. The chsA disruptant grew as well as the wild-type strain, but the chsB disruptant had severe growth defects that could not be overcome by the addition of 1.2M sorbitol as an osmotic stabilizer. These findings suggested that chsB but not chsA is essential for hyphal growth.

Amino Acid Sequence↗
PubMed1994

Isolation of a chitin synthase gene (chsC) of Aspergillus nidulans.

We isolated a class I chitin synthase gene (chsC) from Aspergillus nidulans. Expression of this gene was confirmed by Northern analysis and by sequencing of the PCR-amplified DNA fragments from cDNA. chsC disruptants showed no difference of morphology in the asexual cycle and no difference of growth rate compared to a wild-type strain.

Amino Acid Sequence↗
PubMed1994

[Analysis of nuclear DNA heterogeneity of the hepatocellular carcinoma (HCC)].

To evaluate the objective proliferative activity in HCC nuclear DNA contents were measured by means of microspectrophotometry and at the same time the immunohistochemical technique using anti-PCNA antibody was employed. Surgically resected 26 HCCs were analyzed in terms of cell proliferative activity and regional heterogeneity. The analysis was performed by immunohistochemical demonstration of PCNA and pathologic histochemical study in formalin-fixed, paraffin-embedded specimens and cytophotometric measurements of nuclear DNA contents in fresh specimens. The results were as follows. 1) Nine HCCs showed regional ploidy heterogeneity. 2) PCNA labeling index and histological grade of the marginal area was much higher than that of the central area. From these results, we concluded that in the process of the HCC progression proliferative activity was decreased in the central area and was not decreased in the marginal area.

Carcinoma, Hepatocellular↗
PubMed1994

[Microspectrophotometric analysis of nuclear DNA contents related to the presence of alpha-fetoprotein in human hepatocellular carcinoma].

A total of 28 surgically resected hepatocellular carcinomas, including both fresh-smeared specimens and paraffin-embedded tissues, was stained with alpha-fetoprotein (AFP) antibody. In all cases we measured the DNA contents using microspectrophotometry. In 5 cases, analyses of the nuclear DNA histogram of both the AFP-positive and negative cells from the same specimen were successfully performed. The ratio of the S-G2.M phase of the AFP-positive cells was 2.24 times more than that of the AFP-negative cells. In addition, not only the ratio of S-G2.M phase cells, but also the incidence of aneuploidy pattern of AFP positive stained cases was higher than the negative stained cases. Histologically, the AFP-positive cases contained various differentiated tissues more than the negative cases. From these results, we confirmed that AFP production was related to the growth of HCC, and the results suggest that AFP producing HCC have a higher potential for growth than AFP non-producing HCC.

Carcinoma, Hepatocellular↗
PubMed1994

[Histopathological study of the meibomian glands in 72 autopsy cases].

We investigated histopathological changes in human meibomian glands and analyzed the incidence of histopathological parameters and the relationship between parameters and age or sex of patients. Human meibomian glands, measuring 3 x 3 mm in size, were excised from both upper eyelids of 72 autopsy cases (mean age 63 +/- 12 years; 44 males, 28 females). The specimens were stained with hematoxylin and eosin and examined in detail with the light microscope. The following histopathological changes were investigated as parameters: (1) cystic dilatation of the duct and/or the acini, (2) atrophy of the acini, and (3) granulomatous inflammation. The incidences of the parameters were (1) 34.7% (25 cases), (2) 19.4% (14 cases), and (3) 18.6% (13 cases). There was statistically significant correlation between age and atrophy of the acini, which was found in the older patients. No sex difference was found in any of the parameters. These results suggest that the decrease in the meibomian gland secretion with aging is related to atrophy of the acini. These results further suggest that cystic dilatation, which has been described as a histopathological finding in meibomian gland dysfunction, may be caused by factors other than aging.

Adolescent↗
PubMed1993

Hypouricemic effect of allopurinol and the novel xanthine oxidase inhibitor TEI-6720 in chimpanzees.

The hypouricemic effect of a newly synthesized xanthine oxidase/xanthine dehydrogenase inhibitor, TEI-6720, 2-(3-cyano-4-isobutoxyphenyl)-4-methyl-5-thiazolecarboxylic acid, was investigated and compared with that of allopurinol in male chimpanzees (n = 3). When allopurinol (10 mg/kg) was administered orally once a day for three consecutive days, it cumulatively reduced serum urate levels by 29.7, 50.1 and 60.2%, 24, 48 and 72 h, respectively, after the initial dose. This effect was dose dependent at doses of 3 and 10 mg/kg. At 3 mg/kg, the mean serum urate levels were 3.1, 2.4, 2.5 and 2.3 mg/dl before and 24, 48 and 72 h, respectively, after the initial dose. Animals treated with 10 mg/kg of allopurinol showed serum urate levels of 3.3, 2.3, 1.6 and 1.3 mg/dl, respectively. The urate-lowering effect of TEI-6720 was then compared with that of allopurinol at a daily dose of 5 mg/kg (n = 3). Both compounds caused striking reductions in serum and urinary uric acid levels accompanied by an increase in urinary xanthine levels. These effects of TEI-6720 were more potent than those of allopurinol. TEI-6720 reduced serum urate levels by 55.9, 69.6 and 73.6%, 24, 48 and 72 h, respectively, after the first dose, whereas the corresponding values after allopurinol were 28.1, 41.6 and 45.1%. These results suggest that the hypouricemic effect of TEI-6720 may be more potent than that of allopurinol in the treatment of hyperuricemia and gout, and that TEI-6720 may become an effective alternative drug.

Administration, Oral↗
PubMed1993

Calcium pump expression in human bone and soft tissue tumours.

Ninety-one cases of human bone and soft tissue tumours were studied for calcium pump expression by strepto-avidin-biotin immunohistochemical staining with a monoclonal antibody against sarcoplasmic reticulum calcium-ATPase (mAb6F5). Two out of 5 cases of embryonal rhabdomyosarcoma, 1 out of 5 cases of biphasic synovial sarcoma, 4 of 4 cases of chordoma and all of 3 chondrosarcoma cases were positive for mAb6F5. Although this novel monoclonal antibody can be used as a marker of myogenic tumours, the present positive result for endoplasmic reticulum calcium-ATPase (calcium pump) in other tumours including chordoma, chondrosarcoma and synovial sarcoma indicates a wider immunoreactivity. The findings further suggest that intracellular calcium may play an important role in cell proliferation and/or differentiation.

Adult↗
PubMed1993

Role of Asp51 and Glu105 in the enzymatic activity of a ribonuclease from Rhizopus niveus.

The active site of a base non-specific RNase from Rhizopus niveus (RNase Rh), consists of three histidine residues and one carboxyl group [Ohgi, K. et al. (1992) J. Biochem. 111, 132-138]. In order to identify this acidic amino acid residue, we chose Asp51 and Glu105 as candidates based on a comparison of the primary structures of four fungal RNases and self-incompatibility factors of Nicotiana alata which belong to the RNase T2 family. We substituted these amino acid residues with other amino acids by site-directed mutagenesis, and determined the enzymatic properties of the mutated enzymes. The enzymatic activities of E105Q, E105D, and E105A mutant enzymes were decreased markedly, but those of D51N, D51E, and D51A were decreased only slightly when RNA was used as a substrate. Therefore we concluded that Glu105 is related to the catalytic function. Kinetic constants for the enzymatic activity of E105Q and E105D toward ApU suggest that the proper size and negative charge of side chain groups are important for the catalysis of RNase Rh. However, the enzymatic activity of D51N toward ApU, but not toward UpU, decreased markedly. Therefore, we suggest that Asp51 is one of the amino acid residues forming the base recognition site. The substitution of Asp51 by Asn causes the enzyme to be more guanine nucleotide-preferential.

Amino Acid Sequence↗