Showing papers by "Takashi Saito published in 1999"

Fcγ Receptor–mediated Induction of Dendritic Cell Maturation and Major Histocompatibility Complex Class I–restricted Antigen Presentation after Immune Complex Internalization

Abstract: Dendritic cells (DCs) express several receptors for the Fc portion of immunoglobulin (Ig)G (FcγR), which mediate internalization of antigen–IgG complexes (immune complexes, ICs) and promote efficient major histocompatibility complex (MHC) class II–restricted antigen presentation. We now show that FcγRs have two additional specific attributes in murine DCs: the induction of DC maturation and the promotion of efficient MHC class I–restricted presentation of peptides from exogenous, IgG-complexed antigens. Both FcγR functions require the FcγR-associated γ chain. FcγR-mediated MHC class I–restricted antigen presentation is extremely sensitive and specific to immature DCs. It requires proteasomal degradation and is dependent on functional peptide transporter associated with antigen processing, TAP1-TAP2. By promoting DC maturation and presentation on both MHC class I and II molecules, ICs should efficiently sensitize DCs for priming of both CD4+ helper and CD8+ cytotoxic T lymphocytes in vivo.

Dependence of T Cell Antigen Recognition on the Dimensions of an Accessory Receptor–Ligand Complex

Abstract: The T cell antigen receptor (TCR) and its ligand peptide-major histocompatibility complex (MHC) are small (approximately 7 nm) compared with other abundant cell surface molecules such as integrins, CD43, and CD45 (23-50 nm). We have proposed that molecules at the T cell/antigen-presenting cell (APC) interface segregate according to size, with small "accessory" molecules (e.g., CD2, CD4, CD8, CD28, and CD154) contributing to the formation of a close-contact zone, within which the TCR engages peptide-MHC, and from which large molecules are excluded (Davis, S.J., and P.A. van der Merwe. 1996. Immunol. Today. 17:177-187). One prediction of this model is that increasing the size of these small accessory molecules will disrupt their function. Here, we test this prediction by varying the dimensions of the CD2 ligand, CD48, and examining how this affects T cell antigen recognition. Although the interaction of CD2 on T cells with wild-type or shortened forms of CD48 on APCs enhances T cell antigen recognition, the interaction of CD2 with elongated forms of CD48 is strongly inhibitory. Further experiments indicated that elongation of the CD2/CD48 complex inhibited TCR engagement of peptide-MHC, presumably by preventing the formation of sufficiently intimate contacts at the T cell/APC interface. These findings demonstrate the importance of small size in CD2/CD48 function, and support the hypothesis that T cell antigen recognition requires segregation of cell surface molecules according to size.

Cytotoxic T Lymphocyte Antigen 4 (Ctla-4) Engagement Delivers an Inhibitory Signal through the Membrane-Proximal Region in the Absence of the Tyrosine Motif in the Cytoplasmic Tail

Abstract: Cytotoxic T lymphocyte antigen 4 (CTLA-4) is a T cell costimulation receptor that delivers inhibitory signals upon activation. Although the tyrosine-based motif (165YVKM) within its cytoplasmic tail has been shown to associate in vitro with Src homology 2 domain–containing tyrosine phosphatase (SHP-2) and phosphatidylinositol 3 kinase upon phosphorylation, the mechanism of negative signaling remains unclear. Here, we report a new mechanism of negative signaling based on the analysis of murine T cell clones transfected with various mutants of CTLA-4. Upon T cell activation by cross-linking with anti-CD3 and anti-CD28 antibodies, CTLA-4 engagement inhibited both proliferation and interleukin 2 production in tyrosine mutants as well as in wild-type CTLA-4 transfectants. Furthermore, the mutant CTLA-4 lacking most of the cytoplasmic region strongly suppressed interleukin 2 production as well. These data suggest that negative signals by CTLA-4 could be mediated through the membrane-proximal region of CTLA-4 but not through the YVKM motif and that the association of CTLA-4 with SHP-2 is not required for CTLA-4–mediated suppression of T cell activation.

Method of manufacturing a semiconductor device having a fine pattern, and semiconductor device manufactured thereby

Abstract: There is described a method of stably manufacturing a fine resist pattern narrower than the wavelength of exposing light from a stepper. Under the method, a resist pattern is formed on a semiconductor substrate through use of an acid catalyst chemically-amplified photoresist, and an organic film which includes an acid or which produces an acid on exposure to light is formed on the surface of the semiconductor substrate including the resist pattern. The organic film is then subjected to a heat treatment to thereby diffuse an acid. The surface layer of the resist pattern is made soluble in an alkaline developer, and the surface layer of the resist pattern is removed through use of the alkaline developer. As a result, a fine resist pattern is formed.

Method of treating carbon dioxide-containing gas and apparatus therefor

Abstract: The apparatus of the present invention includes an inverted J-shaped pipe disposed under the sea and including shorter and longer open end portions, and a connecting portion joining them such that the shorter and longer portions extend downward from connecting portion to their respective open ends An injector nut injecting the carbon dioxide-containing gas into a portion of said short pipe adjacent to said first open end into said shorter pipe An accumulator is in fluid communication with the connecting portion for collecting gas, which remains undissolved in the seawater during the passage of the carbon dioxide-containing gas through said shorter pipe According to the method of the invention, the injection of the carbon dioxide-containing gas forces the seawater to enter into first open end, to flow upward together with the carbon dioxide-containing gas through the shorter pipe portion, to flow downward through the longer pipe portion and to be discharged from the second open end, with the carbon dioxide being dissolved in the seawater during the passage of the carbon dioxide-containing gas through the shorter pipe portion, so that the seawater discharged from the second open end contains carbon dioxide dissolved therein

Registration accuracy measurement mark, method of repairing defect of the mark, photomask having the mark, method of manufacturing the photo mask and method of exposure thereof

Abstract: The present invention includes a first semiconductor element forming member formed in a first layer, a first measurement mark formed by the same manufacturing step as the first semiconductor element forming member, a second semiconductor element forming member formed in a second layer above the first layer, and a second measurement mark formed in the same manufacturing step as the second semiconductor element forming member for measuring registration accuracy between the first and second semiconductor element forming members. The first measurement mark has a pattern which receives same influence of aberration as the first semiconductor element forming member when irradiated with light, and the second measurement mark has a pattern which receives same influence of aberration as the second semiconductor element forming member when irradiated with light. Thus, a registration accuracy measurement mark taking into consideration the influence of aberration can be provided.

Ablation of a specific cell population by the replacement of a uniquely expressed gene with a toxin gene.

Abstract: The transgenic expression of a toxin gene or a thymidine kinase gene under the control of cell type-specific promoter/enhancer has been shown to be useful for removing a specific cell population in mice. However, this approach requires extensive analysis of the control elements for gene expression in the preparation of the transgenic constructs, and furthermore, the toxin gene might be expressed ectopically because of random integration, resulting in aberrant depletion of unrelated cells. To avoid such difficulties with the transgenic approach, we established a method for the specific depletion of a cell population by replacing a uniquely expressed gene in the population with the diphtheria toxin gene by using homologous recombination. The NKR-P1 gene, a specific cell surface marker of natural killer (NK) cells, was selected as the target gene for depleting NK cells. In chimeric mice reconstituted with embryonic stem cells in which the NKR-P1 gene was replaced by the toxin gene, NKR-P1+ cells were almost completely depleted, and NK cell function was abrogated in the embryonic stem cell-derived lymphoid cells. Other cell lineages developed normally. These results show that all NK cells express NKR-P1, that NKR-P1+ cells do not influence the development of T and B cells, and further, that this technology of cell targeting is a fast and powerful method of generating mice lacking any chosen cell population.

Protective effects of calpain inhibitor for prolonged hypothermic cardiac preservation.

Abstract: Purpose: For successful organ transplantation, it is important to properly preserve the donor organ. This study was carried out to investigate tissue damage generated by the activation of calpain during prolonged hypothermic cardiac preservation using specific antibodies for μ- and m-calpain proenzymes, and to ensure the protective effect of calpain inhibitor 1 (N-acetyl-leucyl-leucyl-norleucinal). Methods: Excised rat hearts were divided into two groups: in Group I, the heart was arrested and immersed in University of Wisconsin solution with 20 μM of calpain inhibitor 1 (n = 28) and in Group N, the heart was arrested and immersed in University of Wisconsin solution without calpain inhibitor (n = 27). After a 12-hour preservation period at 4°C, the hearts were reperfused on an isolated perfusion apparatus. Separation of the myocardial calpain isozymes was carried out by DEAE cellulose chromatography and both calpain proenzymes were detected by immunoblotting. Results: The cardiac function was more satisfactorily maintained in Group I in comparison with Group N. Remarkable leakage of creatine kinase, glutamic-oxaloacetic transaminase and lactate dehydrogenase was detected in Group N, while it was efficiently suppressed in Group I. During ischemia, μ-calpain proenzyme decreased in Group N (p < 0.01), but there was no significant change in m-calpain. However, during reperfusion, both μ- and m-calpains decreased more in Group N (p < 0.01). Conclusion: Activation of calpain proenzymes and a decrease in cardiac function during preservation and reperfusion were demonstrated. The use of calpain inhibitor to protect against tissue damage was suggested as being useful for the prolonged preservation of the heart.

Grain boundary energy and atomic structure in alumina bicrystals

Abstract: Grain boundary energy is a factor to affect the superplastic flow in ceramic materials. The grain boundary energy in alumina was estimated using high-purity bicrystals, by thermal grooving technique. The alumina bicrystals having a [0001] symmetrical tilt axis were fabricated by joining single crystals at high temperature. The bicrystals include low sigma boundaries (Σ3, Σ7), high sigma boundaries (Σ19 etc.), small angle boundaries and high angle boundaries. Grain boundary energies were mostly in a range 0.4-0.7J/m 2 . Low sigma boundaries Σ3 and Σ7 took an extremely low energy about 0.05J/m 2 . The energy is related to the structure of grain boundaries.

Genomic structure and chromosome mapping of the genes encoding clathrin-associated adaptor medium chains μ1A (Ap1m1) and μ1B (Ap1m2)

Abstract: . The protein μ1B is a member of the medium chain family of the clathrin-associated adaptor complex and is expressed exclusively in epithelial cells. We determined the genomic str

[Evaluation of a new screening assay kit for the combined detection of HIV p24 antigen and antibody--comparison of the performance of the new kit and HIV antibody assay kits].

Abstract: DUO is an automated HIV infection screening test kit based on the combined detection of p24 Ag and anti-HIV-1 and anti-HIV-2 IgG in human sera or plasma using the ELFA technique (Enzyme-Linked Fluorescent Assay). The performance of DUO was compared with that of HIV-1/HIV-2 3rd generation EIA plus and particle agglutination (PA) test. A total of 141 seropositive sera, 3 seroconversion panels, 300 seronegative sera and 387 potentially cross-reactive serum samples were tested. One hundred and forty one seropositive sera in Japan and Cameroon were all positive with DUO. Three seroconversion panels (panel Q, Z, AE) were tested to evaluate sensitivity. In Panel Q, infecution was detected seven days earlier with DUO than with the 3rd generation EIA plus and PA. In Panel AE, infection was detected four days earlier with DUO than with the single antibody assays. Three hundred seronegative sera from Kanagawa prefectural public health centers were all negative with DUO as well as PA test. Three hundred and eighty seven potentially cross-reacting samples were tested to challenge the specificity of the assay. These included samples from pregnant women and hepatitis patients. In four of the 204 samples from pregnant women, false-positive results were observed with DUO. In three of the 183 samples from hepatitis patients, false-positive results were also obtained with DUO. All samples of 7 DUO positive results were negative with western blot test. Five of them were negative with RT-PCR and 2 of them were not tested because there were not enough samples. Thirty cross-reacting (false-positive) samples by PA test from blood donors were tested by DUO, and all of these were negative by DUO.

Semiconductor manufacture device and processing method for wafer

Abstract: PROBLEM TO BE SOLVED: To provide a semiconductor manufacture device which is capable of baking a wafer uniformly. SOLUTION: A hot plate unit 1 is provided with a cover 2. The cover is provided with an inner wall face 2c and a vacuum port 6. A plate 4 having an open pore 4a is provided immediately below the vacuum port 6. An interval between the plate 4 and a main face 7a is equal to an interval between the main face 7a and the inner wall face 2c. Furthermore, the hot plate unit 1 has evacuating amount adjustment valves 5a and 5b for suppressing the evacuation amount to 0.1 (liter/minute) or more and 1 (liter/minute) or lower.

A bidirectional closing aortic dissection from an atherosclerotic distal aortic arch aneurysm: report of a case.

Abstract: We experienced one rare case of a 76-year-old male with a Stanford type A bidirectional closing aortic dissection from a coexisting atherosclerotic distal arch aneurysm. He showed a cardiac tamponade, and effective pericardial drainage allowed us to conservatively manage the patient. Both an increase in the size of the aneurysm and a recrudescent dissection in the descending aorta were identified 2 months after the onset. A scheduled surgical repair was successful. The coexistence of an acute aortic dissection and an atherosclerotic aneurysm increases the risk of an aortic rupture, particularly at the confluence of the two lesions. Meanwhile, the management of a closing aortic dissection remains controversial because its characteristics still are not well known. We studied not only the pathogenesis but also the management of these two forms of aortic disease and their complex relationships.