Biomedical subjects

H Horiuchi

Publications and source records attributed to H Horiuchi.

At least 109 records · Page 6Linked to original sources

PubMed1997

Fc portion of intravenous immunoglobulin suppresses the induction of experimental allergic neuritis.

To clarify how intravenous immunoglobulin (IVIg) acts on Guillain-Barré syndrome, we investigated the effects of intact-type IVIg treatment on experimental allergic neuritis (EAN) induced by immunizing with synthetic peptide from bovine P2 protein. Treatment with intact-type IVIg (400 mg/kg/day) on days 0, 7, 14, 15 and 16 after immunization prevented the paralysis, whereas treatment with F(ab')2 failed to alter the clinical course. Intact-type IVIg treatment given on days 0 and 1 showed almost the same efficacy. These results suggest that intact-type IVIg is superior to F(ab')2 in ameliorating the clinical course of EAN and that the Fc portion might affect the immune system.

Animals↗

PubMed1997

Circulating promyelocytes and low levels of CD16 expression on polymorphonuclear leukocytes accompany early-onset periodontitis.

Early-onset periodontitis (EOP) is characterized by rapidly progressive alveolar bone loss, chemotactic defects of neutrophils, and significant familial aggregation. We found immature myeloid lineage cells, defined as promyelocytes, in the peripheral blood in patients with EOP. A hematological examination of peripheral blood cells showed normal reference values regarding cell proportions. Flow cytometry revealed significantly lower expression of CD16, a glycosylphosphatidylinositol (GPI)-anchored protein, on peripheral neutrophils in patients compared with those in age- and sex-matched healthy controls, whereas the levels of CD11a and CD11b expression were similar. The chemotactic response of neutrophils was lower toward not only formyl-methionyl-leucyl-phenylalanine but also complement fragment C5a than that of healthy controls. The expression of another GPI-anchored protein, CD14, was equally expressed by controls and patients. Therefore, the low level of CD16 expression was not due to the incomplete synthesis of the GPI anchor. GPI anchors of CD16 on neutrophils from controls and patients were both partially resistant to phosphatidylinositol-specific phospholipase C. The presence of promyelocytes in peripheral blood, low expression of CD16, and low chemotactic response of neutrophils suggest that patients with EOP have an abnormal maturation system in myeloid lineage cells in the bone marrow, which may be associated with the onset and course of EOP.

Adult↗

PubMed1997

Evidence that part of a centromeric DNA region induces pseudohyphal growth in a dimorphic yeast, Candida maltosa.

We observed that a YCp-type vector having the centromeric DNA (CEN) sequence previously isolated from the genome, but not a YRp-type vector lacking the CEN sequence, induced pseudohyphal growth in a dimorphic fungi, Candida maltosa, which had been shown to be closely related to Candida albicans by phylogenetic analysis. Deletion analysis of the CEN sequence revealed that the intact CEN sequence was not required for the induction, but part of it, having partial centromeric activity, was enough for the induction. By screening the gene library of this yeast for the sequences which induced pseudohyphal growth, we isolated three different DNA fragments which also had part of the centromere-like sequence. Partial centromeric activity of these fragments was confirmed by three criteria: low copy number and high stability of the plasmids carrying these fragments and rearrangement at high frequency of the plasmid DNA with one of these fragments plus the CEN sequence. Furthermore, when the GGTAGCG sequence commonly found in one copy in each of these four sequences was mutated in the CEN sequence by site-directed mutagenesis, both partial centromeric activity and pseudohyphal growth-inducing activity of the CEN sequence were lost. These results indicated that part of CEN region with partial centromeric activity induces pseudohyphal growth in C. maltosa. It is suggested that some cellular components which interact with the sequence containing GGTAGCG required for centromeric activity are involved in the regulation of the transition between yeast forms and pseudohyphal forms of the cells.

Base Sequence↗

PubMed1997

Effect of intraluminal pressure on the intimal thickening in injured rabbit carotid arteries in an organ-culture system.

We developed an organ culture system in order to examine the effect of intraluminal pressure on intimal thickening in injured arteries. After endothelial denudation, an excised rabbit common carotid artery was incubated at 37 degrees C in a glass bottle perfused with Dulbecco's modified Eagle medium containing 10% fetal calf serum at a constant flow rate of 6 ml/h at various static pressure of 60, 95, 130, 165, or 200 cmH2O. Intimal thickening, which consisted of smooth muscle cells and extracellular matrix, increased in a time- and pressure-dependent manner up to 130 cmH2O. Excessive pressured (165 and 200 cmH2O), however, caused necrosis in the media. These results suggest that a rise in intraluminal pressure accelerates intimal thickening in injured arteries.

Animals↗

PubMed1997

Production of recombinant Der fI with the native IgE-binding activity using a baculovirus expression system.

Der fI is a cysteine protease contained in feces of mites and is one of major mite allergens. Recombinant Der fI (reDer fI) that is produced using a baculovirus expression system contains pro-sequences of different lengths. Most of these can be removed by acid treatment. However, IgE-binding activity of acid-treated reDer fI is lower than that of native Der fI at high protein concentrations, and N-terminal amino acids of acid-treated reDer fI are not uniform. Now, a method for processing of the pro-sequence has been developed by producing reDer fI E(-1)K with baculovirus expression system in which the carboxy terminal amino acid of the pro-sequence (glutamate) was replaced by lysine using site directed mutagenesis. No difference in the amount of production was observed upon introducing the mutation into the pro-sequence. Addition of lysylendopeptidase into the culture medium led to processing of the pro-sequence of reDer fI E(-1)K and proceeded the degradation of the other proteins in the medium. Lysylendopeptidase-treated reDer fI E(-1)K was easily purified with an anion exchange column, resulting in 20% increase of the yield. Lysylendopeptidase-treated reDer fI E(-1)K obtained through these processes was compared with the native Der fI. Although some differences were found in protease activity and reactivity with lectins, their N-terminal amino acid and the IgE-binding activity were the same as those of the native one, indicating its usefulness for diagnostic purpose.

Animals↗

PubMed1996

The Aspergillus nidulans genes chsA and chsD encode chitin synthases which have redundant functions in conidia formation.

We previously isolated three chitin synthase genes (chsA, chsB, and chsC) from Aspergillus nidulans. In the present work, we describe the isolation and characterization of another chitin synthase gene, named chsD, from A. nidulans. Its deduced amino acid sequence shows 56.7% and 55.9% amino acid identity, respectively, with Cal1 of Saccharomyces cerevisiae and Chs3 of Candida albicans. Disruption of chsD caused no defect in cell growth or morphology during the asexual cycle and caused no decrease in chitin content in hyphae. However, double disruption of chsA and chsD caused a remarkable decrease in the efficiency of conidia formation, while double disruption of chsC and chsD caused no defect. Thus it appears that chsA and chsD serve redundant functions in conidia formation.

Amino Acid Sequence↗

PubMed1996

Degradation of Rhizopus niveus aspartic proteinase-I with mutated prosequences occurs in the endoplasmic reticulum of Saccharomyces cerevisiae.

Rhizopus niveus aspartic proteinase-I (RNAP-I) is secreted by Saccharomyces cerevisiae extracellularly (Horiuchi, H., Ashikari, T., Amachi, T., Yoshizumi, H., Takagi, M., and Yano, K. (1990) Agric. Biol. Chem. 54, 1771-1779). The prosequence of RNAP-I has the function to promote correct folding of its mature part. Deletion (Deltapro) and amino acid substitutions (M1) in the prosequence block secretion of RNAP-I (Fukuda, R., Horiuchi, H., Ohta, A., and Takagi, M. (1994) J. Biol. Chem. 269, 9556-9561). In this study, little accumulation of Deltapro was observed in Western blot analysis of the cell extracts of the transformants producing Deltapro using anti-RNAP-I antisera. In contrast, M1 was accumulated in the yeast cells. Pulse-chase analysis revealed that they were synthesized at almost the same rates and that Deltapro was degraded in the cells more rapidly than M1. In subcellular fractionation analysis, Deltapro was found in the fraction that contained most of the activity of an endoplasmic reticulum (ER) marker enzyme, NADPH-cytochrome c reductase. In indirect immunofluorescence microscopy, Deltapro was observed in the ER. Similar result was also observed in a mutant which is deficient of the two vacuolar proteases, proteinase A and proteinase B. So, the vacuolar proteases are not involved in degradation of Deltapro. From these results, we concluded that RNAP-Is with the mutated prosequences, which probably could not be folded correctly, were retained and degraded in the ER.

Alanine↗

PubMed1996

ErbB-2 expression is correlated with poor prognosis for patients with osteosarcoma.

BACKGROUND: It has been reported that the c-erbB-2 protooncogene is frequently amplified and overexpressed in many types of cancers, except sarcomas and hematological malignancies. METHODS: Expression of ErbB-2 in the tumors of 26 patients with conventional osteosarcoma was evaluated by immunoblotting. DNA from osteosarcoma tissues that expressed ErbB-2 were analyzed by Southern blot hybridization to examine gross rearrangement of the gene. The DNA was also surveyed for the presence of genetic mutation in the transmembrane domain of ErbB-2 by polymerase chain reaction-single-stranded DNA conformation polymorphism analysis. In addition, possible correlation of ErbB-2 expression with gender, age, histopathologic subtype, and response to chemotherapy was analyzed. Survival analysis was performed by the Kaplan-Meier test using the approximate chi-square statistic for the log-rank test. RESULTS: The ErbB-2 protein was detected in 11 of 26 osteosarcoma tissues (42%) by immunoblot analysis. Expression of ErbB-2 was confirmed by immunohistochemical studies using specific anti-ErbB-2 monoclonal antibody. However, neither amplification of the c-erbB-2 gene nor evidence of significant genetic mutation was found in these osteosarcomas. Expression of ErbB-2 examined by immunoblotting was most strongly correlated with early pulmonary metastases (P < 0.05). Among the entire group of 26 patients in this study, Kaplan-Meier life table survival of the patients with apparent ErbB-2 expression was significantly worse than that of the patients with little ErbB-2 expression (P < 0.01). CONCLUSIONS: In 42% of the osteosarcomas, the tumor cells expressed ErbB-2. Expression of ErbB-2 was strongly correlated with early pulmonary metastasis and poor survival rate for the patient. These data suggest that ErbB-2 plays a significant role in aggressive tumor growth and in the promotion of metastatic potential in osteosarcomas. ErbB-2 in the osteosarcoma tissues would be a useful prognostic marker for patients.

Adolescent↗

PubMed1996