Showing papers by "Takashi Saito published in 1992"

Human soluble IL-6 receptor: its detection and enhanced release by HIV infection.

Abstract: By using a fluorescence sandwich ELISA for the quantification of soluble human IL-6R, normal human PBMC were found to be induced to release IL-6R into culture supernatant by stimulation with PHA Furthermore, certain promonocyte cell lines and human T-cell leukemia virus I (HTLV-I)-positive cell lines produced sIL-6R into culture supernatants constitutively However, this was not found with HTLV-I negative T cell lines and Burkitt's B cell line In addition, generation of supernatant IL-6R of the promonocyte cell line was significantly increased 27-fold after PMA treatment and sevenfold after infection with HIV The released IL-6R molecules were characterized as an apparent mw of 50 to 55 kDa by both size-exclusion HPLC and immunoprecipitation of the soluble protein with IL-6R-specific mAb followed by SDS-PAGE analysis Furthermore, increased levels of serum IL-6R were detected in blood donors seropositive for HIV Moreover, the released IL-6R could bind efficiently to purified rIL-6 on solid phase and suppressed the proliferative responses of PBMC These results suggest that the release of soluble IL-6R might be linked to regulatory functions of immune responses induced by IL-6 stimulation during normal and human retrovirus-infected cell growth and differentiation

Functional inhibition of hematopoietic and neurotrophic cytokines by blocking the interleukin 6 signal transducer gp130

Abstract: Functional pleiotropy and redundancy are characteristic features of cytokines. To understand the signaling mechanisms of such cytokines, we have proposed a two-chain interleukin (IL) 6 receptor model: IL-6 triggers the association of a ligand-binding chain (IL-6 receptor) and a nonbinding signal transducer (gp130) to form a high-affinity receptor complex, resulting in transmission of the signal by the cytoplasmic portion of gp130. This model would explain the functional redundancy of cytokines if we were to assume that gp130 interacts with several different receptor chains. Here we present data indicating that gp130 functions as a common signal transducer for IL-6, oncostatin M, leukemia inhibitory factor, and ciliary neurotrophic factor. We show that anti-gp130 monoclonal antibodies completely block the biological responses induced by all of these factors. Since leukemia inhibitory factor functions as a cholinergic differentiation factor in nerve cells, as does ciliary neurotrophic factor, these results suggest that gp130 may also play a role in the nervous system.

Structure of a heparan sulphate oligosaccharide that binds to basic fibroblast growth factor.

Abstract: Binding of basic fibroblast growth factor (bFGF) to the extracellular matrix of cultured bovine aorta smooth muscle cells is likely to be mediated via heparan sulphate, since not only exogenous addition of heparan sulphate to the culture medium but also pretreatment of the cells with heparitinase (but not chondroitinase ABC) resulted in loss of binding. Comparison of the affinity of bFGF to various glycosaminoglycan-conjugated gels showed a direct and specific binding of bFGF to heparan sulphate. Heparan sulphate also bound to a bFGF affinity gel. However, the proportion of heparan sulphate bound varied depending on the source of the HS (more than 90% and 45% with pig aorta heparan sulphate and mouse EHS tumour heparan sulphate respectively). The bound heparan sulphate had the ability to protect bFGF from proteolytic digestion, but the unbound heparan sulphate did not. The results suggest the presence in the bound heparan sulphate of a specific structure involved in binding. Limited digestion with heparitinase I of porcine aorta heparan sulphate yielded 13% oligosaccharides bound to the gel, of which the smallest were octasaccharides. Analysis of a hexadecasaccharide fraction which was obtained at the highest yield among the bound oligosaccharides was performed by h.p.l.c. of the deamination products obtained with nitrous acid and the unsaturated disaccharide products formed by heparitinase digestion. Comparison of the disaccharide unit compositions exhibited a marked difference in IdoA(2SO4)GlcNSO3 and IdoA(2SO4)GlcNSO3(6SO4) units between the bound and unbound hexadecasaccharides. The amounts measured were 3 mol and 1 mol per mol of the former and 0.4 mol and 0.6 mol per mol of the latter. It is likely that the binding of bFGF to heparan sulphate may require the domain structure of the heparan sulphate to be composed of clustering IdoA(2SO4)-GlcNSO3 units.

Abnormal distribution of IL-6 receptor in aged MRL/lpr mice: elevated expression on B cells and absence on CD4+ cells.

Abstract: A mAb against murine IL-6 receptor (IL-6R), KMH7, was obtained by immunization of hamster with recombinant soluble murine IL-6R. Flow cytometry analysis of IL-6R distribution on lymphocytes in BALB/c showed that IL-6R was expressed on peripheral lymph node (LN) T cells of either CD4+ or CD8+ phenotype, and Peyer's patch IgA+ B cells, but not on splenic B cells and thymocytes. A similar distribution was observed in 5 week old MRL/lpr and 16-week-old MRL/n mice. In contrast, in 16 week old MRL/lpr mice of both sexes, IL-6R was expressed on splenic IgM+ cells. Peripheral LN CD4+ T cells in 16 week old female MRL/lpr mice did not express IL-6R. Thymocytes in any population with a phenotype of CD4+ or CD8+, double negative, and double positive were not stained with KMH7 in both BALB/c and MRL/lpr mice. In both strains, IL-6R was induced in CD4+ or CD8+ thymocytes after 2 days of culture, suggesting that CD4+ thymocytes in MRL/lpr have a potential to express IL-6R. Our results suggest that overexpression of IL-6R on B cells and absence of IL-6R on peripheral CD4+ cells are concurrent with, or may contribute to, B cell hyperreactivity and T cell abnormality in this strain.

Role of interface states in band structures of short-period (GaAs)n/(Ge2)n

Abstract: We have calculated the band structures of the (GaAs${)}_{\mathit{n}}$/(${\mathrm{Ge}}_{2}$${)}_{\mathit{n}}$ [001] superlattices (SL's) with n=1--10 giving special attention to the role of the interface states at the Ga-Ge and As-Ge polar interfaces. The calculations are performed by means of a semiempirical tight-binding method with an ${\mathit{sp}}^{3}$${\mathit{s}}^{\mathrm{*}}$ basis. The presence of the electric field in the SL is totally ignored, i.e., ``the zero-field model.'' For the (GaAs${)}_{10}$/(${\mathrm{Ge}}_{2}$${)}_{10}$ [001] SL, the band gap is 0.85 eV, with the conduction-band minimum at the X point, into which the fcc L point is folded. The states at the conduction- and valence-band edges are confined two dimensionally in the Ge layers. Furthermore, we have found two interface bands in the lower and upper regions of the gap. The states of the lower interface band are located at the Ga-Ge interface, while those of the upper interface band are located at the As-Ge interface. The energies of the interface states depend on the parameters representing the Ga-Ge and As-Ge bond lengths and the valence-band discontinuity between GaAs and Ge, but the interface states do not disappear from the gap with reasonable choices of the parameters. By decreasing the SL period n, the energy gap between the confined band-edge states increases (1.07 eV at the X point for n=2) due to the quantum confinement effect. A sudden shrinkage in the band gap (${\mathit{E}}_{\mathit{g}}$=0.16 eV at the R point) is obtained for n=1. The origin of the band-gap shrinkage is related to the fact that the overlap of the interface states becomes so large that they combine as band states.

Manufacture of field effect transistor

Abstract: PURPOSE: To realize a gate electrode of a desired size accurately by forming an opaque film on a transparent insulating film formed on a conductive film which becomes a gate electrode, by forming a photoresist thereon and by performing patterning for forming a gate electrode CONSTITUTION: A first insulating film 5 which becomes a gate insulating film is formed on a semiconductor substrate 1, conductive films 7, 9 which becomes a gate electrode are formed thereon and a transparent second insulating film 11 including at least one of a silicon oxide film and a silicon nitride film is formed thereon An opaque film 13 including one or more of a polycrystalline silicon film, an amorphous silicon film, a tungsten silicide film and a titanium nitride film is formed on a second insulating film 11 and a photoresist 15 is formed thereon The photoresist 15 is irradiated with light, patterning for forming a gate electrode is performed and an opaque film 13 below the photoresist 15 is removed after patterning COPYRIGHT: (C)1994,JPO&Japio

Modulation by intracellular calcium pool of arginine vasopressin-induced cellular cyclic AMP production in rat renal papillary collecting tubule cells in culture.

Abstract: The present study was undertaken to determine whether endoplasmic reticulum is involved in the cellular action of arginine vasopressin (AVP) in rat renal papillary collecting tubule cells in culture, using three dissimilar agents. 1 x 10(-7) M AVP increased cytosolic free Ca++ concentration ([Ca++]i) from 93.2 to 188.6 nM (P < .01). Exposure to 1 x 10(-4) M 3, 4, 5-trimethoxybenzoic acid, 8-(diethylamino) octylester hydrochloride (TMB-8), which inhibits intracellular Ca++ mobilization and blocks the function of endoplasmic reticulum, attenuated the [Ca++]i response to AVP. A significant increase in [Ca++]i in response to 1 x 10(-7) M AVP was obtained with Ca(++)-free medium containing 1 x 10(-4) M ethylene glycol bis(beta-aminoethyl ether)N,N'-tetraacetic acid (EGTA) (52.3 to 98.3 nM). However, when cells were preincubated with Ca(++)-free medium containing a mixture of 1 x 10(-4) M EGTA and 1 x 10(-4) M TMB-8, the 1 x 10(-7) M AVP-mobilized [Ca++]i was completely abolished. In the presence of 5 x 10(-4) M 3-isobutyl-1-methylxanthine, AVP increased cellular cyclic AMP (cAMP) production in a dose-dependent manner. Such an AVP-induced cAMP production was significantly reduced in cells exposed to Ca(++)-free medium containing 1 x 10(-4) M EGTA. After exposure to Ca(++)-free medium containing a mixture of 1 x 10(-4) M EGTA and 1 x 10(-4) M TMB-8, the cAMP response to AVP was markedly reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Manufactured of heat exchanger

Abstract: PURPOSE:To provide a manufacturing method of a heat exchanger where a fin and a tube can be mechanically joined without using a lubricant. CONSTITUTION:In the manufacturing method of a heat exchanger where a fin and a tube are mechanically joined by fitting a meandering bent tube in a tube inserting hole of plural fins aligned mutually parallel, the tube inserting hole 5 of the fin 3 is formed with a slot 9 and round holes 11 at both ends of the slot, the tube 7 being collapsed to flat-like shape is inserted in the tube inserting hole 5 and the fin 3 and the tube 7 are joined by pressurizing a tube 7a inside a round hole of the tube inserting hole and restoring to the state being almost near a true circle.