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T Koga

Publications and source records attributed to T Koga.

At least 523 records · Page 29Linked to original sources
PubMed1988

Possible binding sites for inositol 1,4,5-trisphosphate in macrophages.

We reported that an arylazide derivative of inositol 1,4,5-trisphosphate (InsP3) caused irreversible InsP3-induced Ca2+ release from saponin-permeabilized macrophages after photoirradiation. To determine the specific receptors for InsP3, presumably present on the endoplastic reticulum, we synthesized isotope-labeled arylazide derivatives of InsP3; InsP3 was coupled with p-azidobenzoyl [3H]beta-alanine (InsP3-[3H]AB beta A) or p-[125I]azidosalicyl beta-alanine (InsP3-[125I]AS beta A). We report here that three proteins may be associated with the Ca2+ releasing mechanism, in photoirradiated saponin-permeabilized macrophages and in the microsomal fraction.

Animals↗
PubMed1988

Characterization of a low-molecular-weight growth inhibitor formed by density-inhibited, tumorigenic V79 Chinese hamster cells.

A novel type of low-molecular-weight growth-inhibitory factor responsible for the density inhibition of tumorigenic V79 Chinese hamster cells has been purified, if not homogenously, by a series of reverse-phase and gel filtration high-performance liquid chromatography. The factor is an acid-stable, heat-labile substance distinct from antiproliferative nucleoside analogues or polyamines and has a molecular weight of approximately 2000. The biological activity of this inhibitor was enhanced nearly 5-fold by trypsin treatment, thereby suggesting that the inhibitor may be a precursor peptide which becomes an oligopeptide with intense biological activity by proteolysis, or that trypsin treatment allows resultant small molecules to efficiently transfer across the cytoplasmic membrane. This inhibitor reversibly inhibits the growth of a broad spectrum of cell types from neoplastic and nonneoplastic cells from various species. These data suggest that this inhibitor is primarily a growth-regulatory molecule common to mammalian cells and may play an important role in regulating growth of both normal and neoplastic cells.

Animals↗
PubMed1988

Induction of an anti-human type II collagen response by monoclonal anti-idiotypic antibody.

Several distinct epitopes on human type II collagen were defined by using mAb. The presence of species-specific and species-nonspecific (common) epitopes was thus clarified. Anti-idiotypic mAb (Ab2) was developed against one of the antibodies (Ab1) reactive with species-specific epitopes. Thus Ab2 was demonstrated to recognize an idiotope expressed on the Ag-binding site (paratope) of Ab1, since the binding of Ab1 to human type II collagen was blocked by Ab2, and the binding of Ab2 to Ab1 was inhibited by soluble human type II collagen, but not by murine and bovine type II collagens. DBA/1 mice immunized with Ab2 coupled to keyhole limpet hemocyanin produced an antibody (Ab3) specifically reactive with human type II collagen. It was also demonstrated that Ab3 expressed an idiotype similar to that of Ab1. These findings indicate that anti-idiotypic antibody directed against mAb to human type II collagen mimics a species-specific epitope on human type II collagen. The anti-idiotypic antibody bearing internal image of type II collagen will open the way to isolation of the arthritogenic epitope on type II collagen.

Animals↗
PubMed1988

Effects of human recombinant tumor necrosis factor-alpha and interleukin 1 on the synthesis of glycosaminoglycan and DNA in cultured rat costal chondrocytes.

We examined effects of human rTNF alpha on the synthesis of glycosaminoglycan and DNA in cultured rat costal chondrocytes. The effects of human recombinant IL-1 alpha and IL-1 beta were also given attention. rTNF alpha, as well as rIL-1 alpha and rIL-1 beta, decreased the incorporation of [35S]sulfate into glycosaminoglycan to about 10% of the levels in the control. The half-maximal doses of rTNF alpha, rIL-1 alpha or rIL-1 beta required for the suppression of glycosaminoglycan synthesis (by rTNF alpha, rIL-1 alpha, and rIL-1 beta) were 2 ng/ml, 30 ng/ml, or 5 ng/ml, respectively. rTNF alpha stimulated incorporation of [3H]thymidine in the chondrocytes in a dose- and time-dependent manner. DNA synthesis was increased to about threefold over the control cultures in the presence of 1 microgram/ml rTNF alpha for 72 hr. The stimulatory effect of rTNF alpha on DNA synthesis was observed in both subconfluent and confluent cultures, whereas rIL-1 alpha and rIL-1 beta had no stimulatory activity on DNA synthesis. The addition of rTNF alpha to the cultures of chondrocytes stimulated DNA synthesis, even in medium containing no fetal calf serum. The fetal calf serum acted synergistically with rTNF alpha in increasing DNA synthesis. We propose that both TNF and IL-1 may be involved in inflammatory diseases of cartilage, and that TNF alpha, but not IL-1, may have some physiologic growth factor function for chondrocytes.

Animals↗
PubMed1988

Possible physiological role of guanosine triphosphate and inositol 1,4,5-trisphosphate in Ca2+ release in macrophages stimulated with chemotactic peptide.

The release of Ca2+ induced by inositol 1,4,5-trisphosphate (InsP3) in the presence of GTP was examined by using saponin-permeabilized macrophages. The origin and the amount of mobilized Ca2+ in intact macrophages stimulated with chemotactic peptide were also examined to assess the physiological significance of GTP and InsP3 on Ca2+-releasing activities. The total amount of Ca2+ released by 20 microM-A23187 from the unstimulated intact macrophages was 1.4 nmol/4 x 10(6) cells, and the mitochondrial uncoupler did not cause an efflux of Ca2+ from the cells. The Ca2+ accumulation by the non-mitochondrial pool(s) was inhibited by the presence of GTP, and the total amount of releasable Ca2+ (1.4 nmol/4 x 10(6) cells) was comparable with that accumulated by the non-mitochondrial pool(s) in the presence of GTP at a free Ca2+ concentration of 0.14 microM. The mobilized and subsequently effluxed Ca2+ in cells stimulated with chemotactic peptide was estimated to be 0.3 nmol/4 x 10(6) cells. Much the same amounts were released by about the half-maximal dose of InsP3 from the non-mitochondrial pool(s) of saponin-treated macrophages that had accumulated Ca2+ at a free concentration of 0.14 microM in the presence of GTP. These results suggest that the Ca2+-releasing activity induced by GTP may play a role in the long-term regulation of Ca2+ content in the non-mitochondrial pool(s) of macrophages, and that released by InsP3 can explain, quantitatively, the chemotactic-peptide-induced mobilization of Ca2+.

Animals↗
PubMed1988

Isolation of T cell line capable of protecting mice against collagen-induced arthritis.

A T cell line specific to human type II collagen (CII) was selected and propagated from DBA/1J mice immunized with human CII. The line cells were not reactive to type I or type III collagen of human origin, but they were cross-reactive to bovine, rat, and rabbit CII and they recognized both native and heat-denatured human CII. The cells were reactive to an N-terminal three-quarters fragment of human CII, produced by tadpole collagenase digestion of human CII, but not to a C-terminal one-quarter fragment of human CII. The cells showed Thy-1+, Lyt-1+, Lyt-2-, and L3T4+ phenotypes characteristic of T helper cells or delayed-type hypersensitive cells, determined by the immunofluorescence method. To clarify the role of T cells in the pathogenesis of collagen-induced arthritis, we inoculated this cell line into DBA/1J mice and found that they developed clinical arthritis, albeit at a low incidence. The cells attenuated by x-ray were capable of inducing resistance to the subsequent induction of collagen-induced arthritis of DBA/1J mice. The sera from mice protected by inoculation of the cell line exhibited anti-idiotypic antibody response against conventional and monoclonal anti-CII antibodies. Anti-T cell receptor response may be involved in the mechanism for the protective effect of the cell line against autoimmune murine arthritis.

Animals↗
PubMed1988

In vitro primary induction of T cells mediating delayed footpad reaction and acquired cellular resistance to Listeria monocytogenes.

We established an in vitro system generating L. monocytogenes-specific T cells primarily from unprimed spleen cells of mice. Normal spleen cells were cultured for 5 days in the presence of L. monocytogenes in vitro. Viable cells were harvested and assessed for their capacity to confer acquired cellular resistance (ACR) and delayed footpad reaction (DFR) upon local passive transfer to naive syngeneic recipient mice. When normal spleen cells were stimulated with viable L. monocytogenes, the viable cells that were recovered after 5 days of culture conferred a high level of ACR and DFR. Negative selection revealed that the effector cells obtained in primary in vitro culture were Thy 1+, L3T4+, Lyt2- cells. T cells mediating ACR could not be generated in the culture of normal spleen cells with heat-killed bacteria; however, cells mediating only DFR were generated in the presence of a large number of killed L. monocytogenes. The expression of DFR and ACR by T cells generated in this primary culture system was Listeria-specific; reactions were not observed against unrelated bacterial antigens including S. typhimurium, S. aureus, E. coli and PPD. FACS analysis of the cells in culture showed that L3T4+ and Lyt2- T cells were being enriched during culture. The primary generation of antigen-specific T cells in vitro was also possible with spleen cells from NTx mice but not with cells from nude mice, suggesting the presence of Listeria-specific precursors in NTx mice.

Animals↗
PubMed1988

Electron-microscopic observation of adherence of serotype c Streptococcus mutans to the enamel surface due to glucan synthesis.

Cellular adherence of three strains with water-insoluble glucan (IG)-synthesizing ability and a strain lacking the ability of serotype c Streptococcus mutans to the saliva-coated human enamel surface was examined by scanning (SEM) and transmission (TEM) electron-microscopy. SEM revealed that organisms of all strains used adhered directly to the enamel surface in the absence of sucrose. Cell-to-cell attachment was scarcely observed in the absence of sucrose. Cell-to-cell attachment via amorphous substance on the cell surface was observed by SEM when the strains with IG-synthesizing ability were incubated with the saliva-coated enamel in the presence of sucrose. TEM revealed that cell-associated enzymes of these strains synthesized filamentous and double-stranded fibrillar structures from sucrose. The strain lacking IG-synthesizing ability was unable to induce cell-to-cell attachment in the presence of sucrose, nor was it able to synthesize the amorphous substance. These results indicate that production of IG by cell-associated glucosyltransferase participates in cellular accumulation of serotype c S. mutans.

Bacterial Adhesion↗
PubMed1988

Ageing suppresses endothelium-dependent relaxation and generates contraction mediated by the muscarinic receptors in vascular smooth muscle of normotensive Wistar-Kyoto and spontaneously hypertensive rats.

We evaluated the effects of ageing and hypertension on endothelium-dependent relaxation and contraction of vascular smooth muscles. Aortic rings with and without endothelium from normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR), divided into young, adult and old groups, were examined for relaxation in response to acetylcholine, adenosine triphosphate (ATP) and sodium nitroprusside. Relaxation responses to acetylcholine and ATP in SHR were either equal to or greater than those in WKY. Relaxations induced by ATP were not altered by ageing, while the degree of acetylcholine-induced endothelium-dependent relaxations was in an inverse order of age in both SHR and WKY. In old SHR and WKY and adult SHR, lower doses of acetylcholine caused relaxations, but increases in the dose of acetylcholine induced contraction. Acetylcholine-induced contractions were abolished by indomethacin or endothelium rubbing. We conclude that endothelium-dependent relaxations are not diminished by spontaneous hypertension but the relaxations mediated by the muscarinic receptors are reduced with ageing. Further, acetylcholine causes endothelium-dependent contractions by releasing cyclo-oxygenase products, not only in SHR but also in aged normotensive WKY.

Acetylcholine↗
PubMed1988

Serological properties and immunobiological activities of lipopolysaccharides from black-pigmented and related oral Bacteroides species.

Lipopolysaccharides (LPS) from five species of oral Bacteroides, B. gingivalis strains 381 and ATCC 33277, B. oralis ATCC 33269, B. loescheii ATCC 15930, B. intermedius ATCC 25611 and B. corporis ATCC 33547, were extracted from whole cells by the phenol/water procedure, and subsequently purified by treatment with nuclease and ultracentrifugation. The LPS were composed of hexoses, glucosamine, fatty acids and phosphorus. Heptose and 2-keto-3-deoxyoctonate were not detected. The LPS preparations from B. gingivalis strains 381 and ATCC 33277 presented very similar SDS-polyacrylamide gel electrophoresis patterns when stained with ammoniacal silver. They produced a fused precipitin band against an antiserum to B. gingivalis 381 LPS in immunodiffusion tests. Antisera raised against the LPS from B. loescheii and B. intermedius reacted with the LPS prepared from all the oral Bacteroides strains except those of B. gingivalis. All the LPS preparations were mitogenic for spleen cells of BALB/c (nu/nu) mice, but not for thymus cells from C3H/HeN mice. The LPS induced marked mitogenic responses and polyclonal B cell activation for spleen cells of not only C3H/HeN (LPS responder) mice, but also C3H/HeJ (LPS nonresponder) mice. The mitogenic responses were not suppressed significantly upon addition of polymyxin B to the reaction mixture. These LPS also enhanced interleukin-1 production by murine peritoneal macrophages and mouse cell line J744. 1 macrophages. Hydrolysis of B. gingivalis ATCC 33277 LPS in 1 m-HCl at 100 degrees C for 1 h yielded lipid and polysaccharide. The lipid portion was largely composed of fatty acids and glucosamine, and was mitogenic for spleen cells from C3H/HeJ as well as C3H/HeN mice, while the polysaccharide portion induced no significant mitogenic responses under similar experimental conditions.

Animals↗
PubMed1988

Immunobiological properties of lipopolysaccharides isolated from Fusobacterium nucleatum and F. necrophorum.

Lipopolysaccharides (LPSs) were isolated from Fusobacterium nucleatum ATCC 10953 and F. necrophorum ATCC 25286 by the hot phenol/water procedure. F. nucleatum LPS was composed of 16% (w/w) carbohydrate, 10% (w/w) hexosamine and 40% (w/w) fatty acid, while F. necrophorum LPS was composed of 26% (w/w) carbohydrate, 12% (w/w) hexosamine and 28% (w/w) fatty acid. These LPS preparations induced mitogenic responses in spleen cells of BALB/c, BALB/c (nu/nu) and C3H/HeN mice, and these responses were suppressed by the addition of polymyxin B. The preparations also induced the polyclonal responses of C3H/HeN spleen cells. In addition, enhanced glucose utilization and interleukin-1 production by murine peritoneal macrophages were demonstrated. Neither spleen cells nor macrophages from the 'LPS-nonresponsive' C3H/HeJ mouse were activated by LPSs from the Fusobacterium species.

Animals↗
PubMed1988

Effects of panose on glucan synthesis and cellular adherence by Streptococcus mutans.

The effects of panose on glucan synthesis and sucrose-dependent cellular adherence by Streptococcus mutans were investigated. Panose effectively inhibited glucan synthesis from sucrose by glucosyltransferases from S. mutans strain 6715, but increasing amounts of panose increased the release of fructose from sucrose by the enzymes. On the other hand, production of a series of oligosaccharides of increasing size by the enzymes was markedly enhanced in the presence of panose. These results indicate that panose activates the enzymes and that the inhibition of glucan synthesis by panose is due to the transfer of the glucosyl group of sucrose to panose. Sucrose-dependent adherence of cells of various S. mutans strains to a glass surface was also inhibited by panose.

Bacterial Adhesion↗
PubMed1988

Production of an interleukin-1 inhibitor by cell line P388D1 murine macrophages stimulated with Haemophilus actinomycetemcomitans lipopolysaccharide.

Murine macrophages of the P388D1 cell line stimulated with lipopolysaccharide (LPS) from Haemophilus actinomycetemcomitans Y4 released an interleukin-1 (IL-1) inhibitor, as well as IL-1. Maximal IL-1 activity in culture supernatants was detected after 24 h of culture. On the other hand, IL-1 inhibitor activity reached a maximum level after 72 h of culture. An IL-1 inhibitor was partially purified from the culture supernatant of P388D1 cells stimulated with Y4 LPS for 72 h by ammonium sulfate precipitation, followed by Sephacryl S-200 gel chromatography. A 160-kilodalton peak inhibitory to IL-1 and a 14-kilodalton peak showing IL-1 activity were separated by Sephacryl S-200 column chromatography. The partially purified IL-1 inhibitor significantly suppressed the proliferation of C3H/HeJ murine thymocytes that had been induced with murine and human IL-1 in the presence of a submitogenic dose of concanavalin A. The IL-1 inhibitor more strongly suppressed human recombinant IL-1 beta than human recombinant IL-1 alpha. This inhibitory activity of the partially purified preparation was unaffected by the presence of trypsin inhibitor and the protease inhibitor aprotinin. The IL-1 inhibitor did not exhibit either IL-2 or IL-2 inhibitor activity. The inhibitor suppressed C3H/HeJ thymocyte proliferation induced by IL-1 in the presence of a saturated concentration of IL-2 instead of a suboptimal concentration of concanavalin A. These results indicate that prolonged culture of Y4 LPS-stimulated murine macrophages releases a specific inhibitor of IL-1.

Animals↗
PubMed1988

Suppression of murine macrophage interleukin-1 release by the polysaccharide portion of Haemophilus actinomycetemcomitans lipopolysaccharide.

Lipopolysaccharide (LPS) was extracted from whole cells of Haemophilus actinomycetemcomitans Y4 by the hot phenol-water procedure. LPS was cleaved into its lipid A and polysaccharide moieties by hydrolysis in 1% acetic acid. The major component sugars of the polysaccharide were glucose, heptose, rhamnose, galactose, and fucose. LPS and lipid A from H. actinomycetemcomitans induced the release of interleukin-1 (IL-1) by LPS-responsive C3H/HeN murine peritoneal macrophages and cell line macrophages (P388D1 and J744.1), but not by LPS-nonresponsive C3H/HeJ peritoneal macrophages. The polysaccharide was unable to induce the release of IL-1. It suppressed the IL-1 release from LPS- and lipid A-stimulated macrophages, but not the production of cell-associated and intracellular IL-1. The addition of rhamnose, a sugar component of the polysaccharide, abrogated the inhibitory effect of the polysaccharide on IL-1 release. These results suggest the participation of a lectinlike molecule in IL-1 release.

Cell Line↗