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Biomedical subjects

Y Murayama

Publications and source records attributed to Y Murayama.

At least 163 records · Page 9Linked to original sources
PubMed1994

Role of cytokine in the induction of adhesion molecules on cultured human gingival fibroblasts.

This study was undertaken in an effort to understand the role of cytokines on human gingival fibroblasts and T lymphocyte trafficking into inflamed gingival tissue. Using flow cytometry we examined gingival fibroblasts to determine the level of cell surface expression and the percentage of cells positive for intercellular adhesion molecule 1 (ICAM-1), the HLA-DR antigen, lymphocyte function-associated antigen 3 (LFA-3), and the CD44 molecule, which are involved in antigen presentation. The following cytokines were used: interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), IL-6, and IL-8. The levels of ICAM-1 expression were enhanced in a dose- and time-dependent manner by IL-1 beta, TNF-alpha, or IFN-gamma, but not by IL-6 or IL-8. HLA-DR surface expression was induced only by IFN-gamma in a dose- and time-dependent manner, but not by the other cytokines tested. In contrast, the expression of LFA-3 and the CD44 molecule could be detected without the stimulation of any cytokine, but the levels of their expression were not significantly changed by any cytokines. The enhanced ICAM-1 expression by cytokines was reduced in a time-dependent manner following the removal of cytokines from the reaction mixture, while IFN-gamma-induced HLA-DR expression was maintained even 7 days after the removal of IFN-gamma. These data support an interactive role for inflammatory cytokines and the expression of adhesion molecules on gingival fibroblasts in the pathogenesis of gingival inflammation in periodontal disease.

Antigen-Presenting Cells↗
PubMed1994

The inhibition of interferon-gamma-induced upregulation of HLA-DR expression on cultured human gingival fibroblasts by interleukin-1 beta or tumor necrosis factor-alpha.

The purpose of this study was to examine the effect of inflammatory cytokines on IFN-gamma-induced HLA-DR expression on cultured human gingival fibroblasts by flow cytometry. Natural human IFN-gamma, recombinant human interleukin-1 beta (rhIL-1 beta), and rh tumor necrosis factor-alpha (rhTNF-alpha) were used. IFN-gamma-induced upregulation of HLA-DR expression was inhibited by simultaneously adding rhIL-1 beta or rhTNF-alpha (65.9% and 31.4% inhibition, respectively). Both rhIL-1 beta and rhTNF-alpha induced endogenous prostaglandin E2 (PGE2) from gingival fibroblasts, while IFN-gamma did not. The inhibitory effect of rhIL-1 beta or rhTNF-alpha on IFN-gamma-induced upregulation of HLA-DR expression was partially abated in the presence of indomethacin (reductions of 65.9% and 41.7%, respectively). Both rhIL-1 beta- and rhTNF-alpha-induced endogenous PGE2 synthesis were completely inhibited by adding indomethacin (P < 0.001). The addition of exogenous PGE2 inhibited the IFN-gamma-induced HLA-DR expression (P < 0.001). These observations suggest that the MCH class II expression on human gingival fibroblasts are influenced by the cytokine network and indirectly by the cytokine-mediated fibroblast PGE2.

Adult↗
PubMed1994

Unique intronic variations of HLA-DQ beta gene in early-onset periodontitis.

Human leukocyte antigen (HLA) class II beta chain plays an important role in the recognition of foreign antigens in immune reactions. Different forms of immune reaction may be concerned with initiation and progression of infectious diseases such as periodontitis. In this study we examined the frequency of HLA class II serotype and the variation of HLA class II beta gene in periodontitis patients. HLA serotypic frequencies in 70 Japanese patients with periodontitis and 26 individuals with periodontal health were examined. No HLA serotype specific to any type of periodontitis was observed. In order to detect differences among some HLA serotypes, restriction fragment length polymorphism (RFLP) analysis was undertaken with cDNA probes for HLA-DR beta and HLA-DQ beta genes in 20 subjects (15 patients and 5 healthy individuals). Atypical BamHI and EcoRI restriction sites were found in the HLA-DQ beta gene from 3 patients with early-onset periodontitis. In addition to these 20 subjects, an additional 80 subjects (40 patients and 40 healthy individuals) were screened for the atypical BamHI restriction site using the polymerase chain reaction method. It was detected in 7 patients with early-onset periodontitis, 1 patient with adult periodontitis, and 3 healthy subjects. No clinical differences except age were found between patients with this gene variation and other patients. Interestingly, all 3 healthy subjects with this gene variation were from subjects whose family members developed early-onset periodontitis with the gene variation. Atypical BamHI and EcoRI restriction sites and 41-nt repeated sequence were found in the intron before the third exon of HLA-DQB gene. These results suggest that these intronic gene variations may be useful as gene markers for a subpopulation of early-onset periodontitis and might affect immune reactions such as antigen recognition.

Adolescent↗
PubMed1994

Biochemical properties of the major outer membrane proteins of Porphyromonas gingivalis.

The major outer membrane proteins (MOMP) of 53 and 67 kDa were identified by sodium dodecyl sulphate-polyacrylamide gel electrophoresis in outer membrane enriched fractions of Porphyromonas gingivalis FDC 381 and ATCC 33277, respectively. The MOMP were purified by anion exchange and gel filtration chromatography after extraction with Zwittergent 3-14. Their reactivity to monoclonal antibodies and their amino acid composition were analysed. The N-terminal amino acid sequences of twenty residues of both purified MOMP were determined and compared with those previously reported for MOMP of other periodontopathic bacteria.

Amino Acid Sequence↗
PubMed1993

Conversion of G-protein specificity of insulin-like growth factor II/mannose 6-phosphate receptor by exchanging of a short region with beta-adrenergic receptor.

The 14-residue peptide (peptide 14) corresponding to Arg2410-Lys2423 of the insulin-like growth factor II receptor (IGF-IIR) can activate the adenylate cyclase-inhibitor guanine nucleotide-binding protein Gi, and the 15-residue beta III-2 peptide Arg259-Lys273 of the beta 2-adrenergic receptor (beta 2AR) can activate the stimulatory protein Gs. In phospholipid vesicles, IGF-IIR and beta 2AR activate Gi and Gs in response to IGF-II and isoproterenol, respectively. We constructed a chimeric IGF-II receptor (beta III-2/IGF-IIR) by converting its native peptide 14 sequence to the beta III-2 sequence. In cells expressing beta III-2/IGF-IIR, membrane adenylate cyclase activity markedly increased without IGF-II and was further promoted by IGF-II. This was verified by measuring chloramphenicol acetyltransferase (CAT) activity in beta III-2/IGF-IIR cells with cotransfection of a cAMP response element-CAT construct. This study shows not only the conversion of G-protein specificity of a receptor from Gi to Gs but also the simulation of G protein-coupled receptor signals by using a short receptor region and intact cells. These findings indicate that the G protein-activation signals are interchangeable, self-determined structural motifs that function in the setting of either a single-spanning or multiple-spanning receptor.

Adenylyl Cyclases↗
PubMed1993

GTP-binding protein-activator sequences in the insulin receptor.

Some functions of the insulin receptor (insR) are assumed to be mediated by pertussis toxin-sensitive Gi/G(o) proteins. Here we have located G-protein-activator domains in the cytoplasmic region of the human insR. We searched the sequence of insR and found three candidate regions at residues 1039-1061, 1147-1168 and 1325-1345, referred to as ISRP1, ISRP2 and ISRP3, respectively. Among them, the Gi/G(o)-activating function was observed only in peptide ISRP3. ISRP1 specifically activated Gs, whereas ISRP2 had no effect on G proteins. ISRP2 and ISRP3 contained five of six autophosphorylated tyrosine residues in insR. After tyrosine phosphorylation, ISRP2 showed specific Gi-activating function, and ISRP3 potentiated its ability and became capable of activating G proteins generally. This is the first study that specifies G-protein-activator domains in insR and describes their modification by autophosphorylation.

Amino Acid Sequence↗
PubMed1993

[A morphological study of the lesioned carotid artery--comparison with WHHL rabbit and Japanese white rabbit].

It is necessary for a neurosurgeon to know the course of repair of vascular injury caused by the procedure of an operation. And further more, it is very important to understand how existence of hypercholesteremia would affect it. Injuries of operations were caused to carotid arteries of Watanabe heritable hyperlipidemic (WHHL) rabbit and a morphological study of the course of repair was made. Japanese white rabbit (JWR) were treated exactly same as WHHL, and their course of repair was compared and examined as control. One week after operation, both WHHL rabbit and JWR showed edematous thickening of a intima, increase in grade of thickening which was continued until two of three months after operation was observed, however gradually decrease thereafter. In case of WHHL rabbit, thickened intima at suture portion was formed by smooth muscle cells migrated from media. Foamy cells were not observed here. The grade of thickening of WHHL rabbits was lower than that of JWR, and that WHHL rabbits tended to show slower change of elastofibrosis in thickened intima rather than JWR. It was considered that the smooth muscle cells of WHHL rabbit has a poor activity naturally.

Animals↗
PubMed1993

Molecular cloning and characterization of mouse TIE and TEK receptor tyrosine kinase genes and their expression in hematopoietic stem cells.

To identify receptor tyrosine kinases (RTKs) critical to early hematopoiesis, we performed polymerase chain reaction-based cloning from yolk sac and highly enriched bone marrow hematopoietic stem cells (HSCs). Characterization of two novel genes of their full-length cDNA sequences revealed that they were mouse homologues of the endothelial cell RTK genes, TIE and TEK. They shared a unique structural property of coexistent immunoglobulin-like domain, epidermal growth factor-like repeats, and fibronectin type III repeats in their extracellular domains. Both genes were expressed in a similar fashion in adult tissues and primitive hematopoietic cells, predominantly in the bone marrow HSCs.

Amino Acid Sequence↗
PubMed1993

Antigenic properties of Campylobacter rectus (Wolinella recta) major S-layer proteins.

The antigenic properties of the surface layer (S-layer) proteins of various Campylobacter rectus strains including 24 clinical isolates and the type strain ATCC 33238 were examined. S-layer proteins were extracted from whole cells by acid treatment according to the method of McCoy et al. (Infect. Immun. 11, 517-525, 1975). The acid extracts from 23 of the isolates and ATCC 33238 contained two major proteins with molecular masses of 130 kDa and 150 kDa, both of which were identified as subunits of the S-layer after comparison with the protein profiles of acid-treated (S-layer-deficient) cells. An S-layer protein from one isolate (CI-808) demonstrated a different molecular mass (160 kDa). Both the 150-kDa proteins of ATCC 33238 and isolate CI-306 and the 160-kDa protein of CI-808 were purified by ion-exchange chromatography in the presence of urea. In Ouchterlony immunodiffusion experiments with these purified proteins and rabbit antiserum raised to each purified protein, both common and strain-specific antigenic determinants were identified in the C. rectus S-layer proteins.

Antigens, Bacterial↗
PubMed1993

Alzheimer amyloid protein precursor complexes with brain GTP-binding protein G(o)

The most characteristic change in progressive dementia of Alzheimer's type is a tissue deposit of amyloid beta/A4 protein, which is derived from its precursor protein APP (ref.2). Structural alterations of APP are implicated in the pathogenesis of Alzheimer's disease, but it is not known how they cause the disease. Although APP has a receptor-like architecture, is located on the neuronal surface, and has a conserved cytoplasmic domain, no receptor function has been demonstrated for APP. Here we report that APP forms a complex with G(o), a major GTP-binding protein in brain. The cytoplasmic APP sequence His 657-Lys 676 shows a specific G(o)-activating function and is necessary for complex formation. G(o) protein treated with GTP-gamma S lost the ability to associate with APP. This suggests that APP is a receptor coupled to G(o) and that abnormal APP-G(o) signalling is involved in the Alzheimer's disease process.

Amino Acid Sequence↗
PubMed1993

Purification of chloroplast elongation factor Tu and cDNA analysis in tobacco: the existence of two chloroplast elongation factor Tu species.

We have purified a chloroplast elongation factor Tu (EF-Tu) from tobacco (Nicotiana tabacum) and determined its N-terminal amino acid sequence. Two distinct cDNAs encoding EF-Tu were isolated from a leaf cDNA library of N. sylvestris (the female progenitor of N. tabacum) using an oligonucleotide probe based on the EF-Tu protein sequence. The cDNA sequence and genomic Southern analyses revealed that tobacco chloroplast EF-Tu is encoded by two distinct genes in the nuclear genome of N. sylvestris. We designated the corresponding gene products EF-Tu A and B. The mature polypeptides of EF-Tu A and B are 408 amino acids long and share 95.3% amino acid identity. They show 75-78% amino acid identity with cyanobacterial and chloroplast-encoded EF-Tu species.

Amino Acid Sequence↗
PubMed1993

Association of Actinobacillus actinomycetemcomitans leukotoxin with nucleic acids on the bacterial cell surface.

Actinobacillus actinomycetemcomitans, a periodontopathic gram-negative bacterium, produces a leukotoxin that is a member of the RTX cytotoxin family. Although genes may function in toxin secretion, the leukotoxin is not secreted extracellularly but remains associated with the bacterial cell surface. We report here that this toxin-cell surface association is mediated by nucleic acids and directly demonstrate that the extracellular secretion of toxin occurs in growing cultures with increased ionic strength of medium. All examinations were performed with freshly harvested A. actinomycetemcomitans 301-b from anaerobic fructose-limited chemostat cultures. The occurrence of cell surface-localized DNA was shown by directly digesting whole cells with the restriction endonuclease EcoRI or HindIII, which yielded many DNA fragments. The cell surface DNA constituted about 20% of the total cellular DNA. The leukotoxin was released from the whole cells by digestion with DNase I as well as restriction endonucleases. Because the leukotoxin binds ionically to DNA, it is dependent on the ionic strength of buffers or media. Accordingly, the toxin was released from cells suspended in saline at pH 7.5 in the presence of increasing amounts of MgCl2 (0 to 10 mM) or NaCl (0 to 50 mM). Moreover, a considerable quantity of leukotoxin was detected in the culture supernatant of fructose-limited chemostat cultures when sodium succinate solution was pumped into the steady state as an additional salt (30 and then 50 mM). This toxin-DNA association was also found in well-characterized strains including not only the leukotoxin-producing ATCC 29522 but also the toxin production-variable ATCC 29523 and the non-leukotoxin-producing ATCC 33384 when these strains were grown in the chemostat culture.

Aggregatibacter actinomycetemcomitans↗
PubMed1993

Calcium-dependent protein kinase C activity of neutrophils in localized juvenile periodontitis.

Protein kinase C is a key molecule in neutrophil signal transduction after receptor stimulation by soluble bioactive molecules. It has been reported that neutrophils from most patients with localized juvenile periodontitis (LJP) do not have a normal response after stimulation with a chemotactic ligand such as N-formylmethionylleucylphenylalanine (FMLP). To further clarify the mechanism of this altered response and to confirm and expand earlier observations, the calcium-dependent protein kinase C activity of neutrophils from patients with LJP was evaluated. Peripheral blood neutrophils from 12 patients and 12 healthy subjects, age, sex, and race matched, were sonicated and subsequently subfractionated by ultracentrifugation into a soluble fraction (cytosol rich) and a particulate fraction (membrane rich). The calcium-dependent protein kinase C activity was evaluated in each fraction by phosphorylation of histone with radiolabeled ATP in the presence or in the absence of phorbol 12-myristate 13-acetate stimulation. Results revealed that the total calcium-dependent protein kinase C activity of neutrophils from patients with LJP and depressed chemotactic migration to FMLP (201.0 +/- 63.6 pmol/min/10(7) cells) was lower than that of neutrophils from healthy subjects (287.6 +/- 55.7 pmol/min/10(7) cells) (P < 0.01). The calcium-dependent protein kinase C activity in neutrophils from patients with LJP exhibited a positive correlation with chemotactic migration to FMLP (P < 0.05). The low activity of calcium-dependent protein kinase C in neutrophils from the patients reflected the low activity in the soluble fraction from the neutrophils. After stimulation with phorbol 12-myristate 13-acetate, the calcium-dependent protein kinase C activity was found to be lower from patients with LJP than from healthy subjects. These results suggest that lower calcium-dependent protein kinase C in neutrophils is a predisposing factor for LJP.

Aggressive Periodontitis↗
PubMed1993

Abnormal proportion of gamma delta T cells in peripheral blood is frequently detected in patients with periodontal disease.

The proportions of gamma delta T cells in the peripheral blood of 8 early-onset periodontitis (EOP) patients, 8 later-onset periodontitis (LOP) patients, and of 17 healthy subjects (HS) were assessed by immunofluorescence assay using an anti-pan gamma delta T cell monoclonal antibody (TCR-delta 1) to study the population attributes of peripheral blood gamma delta T cells in patients with periodontal disease. The distribution of the proportions of gamma delta T cells in both EOP and LOP patients was found to be one and one half times broader than that in the HS; however, there was no significant difference in the proportion of gamma delta T cells between each group. An abnormally high proportion of peripheral blood gamma delta T cells in pan T cells (> 9.90%) was observed in 37.5% of both the EOP patients and the LOP patients. An abnormally low proportion (< 5.57%) was observed in 50% of the EOP patients and in 25% of the LOP patients. The higher occurrences of the high or low gamma delta T cell proportions were significant between EOP and HS, and between EOP+LOP and HS. There was no correlation between the proportion of gamma delta T cells and age or the clinical parameters of periodontal status. It was concluded that an abnormal proportion of gamma delta T cells is frequently detected in patients with periodontal disease. These findings are consistent with the proposed role of the gamma delta T cells for playing a unique role as a first line defense against infections at body surfaces.

Adolescent↗
PubMed1993

Marked increase in fundic mucosal histidine decarboxylase activity in a patient with H+,K(+)-ATPase antibody-positive autoimmune gastritis.

A 63-year-old woman was diagnosed as autoimmune gastritis by the presence of serum antibody against alpha-subunit of gastric H+,K(+)-ATPase. The patient did not have pernicious anemia, but showed achlorhydria, marked hypergastrinemia, enterochromaffin-like cell hyperplasia and an extremely high histidine decarboxylase activity in the gastric fundic mucosa. Intragastric acidification by infusion of hydrochloric acid via a nasogastric tube induced a transient reduction of serum gastrin level and fundic mucosal histidine decarboxylase activity. A marked increase in fundic mucosal histidine decarboxylase activity as well as hypergastrinemia appears to be the pathophysiologic response to achlorhydria caused by autoimmunity against gastric H+,K(+)-ATPase.

Achlorhydria↗