Search PubMed⌕ Search

Biomedical subjects

N Sakaguchi

Publications and source records attributed to N Sakaguchi.

At least 127 records · Page 7Linked to original sources
PubMed1992

The expression of the mouse VpreB/lambda 5 locus in transformed cell lines and tumors of the B lineage differentiation pathway.

The expression of RNA transcripts from two pre B lymphocyte related genes, VpreB and lambda 5, has been studied in a series of transformed cell lines which appear frozen at different states of B lineage differentiation, from early progenitors to surface Ig positive B cells. In the HAFTL-1 cell line, which arose from fetal liver by transformation with a retrovirus containing the Hras oncogene, Northern analysis of poly A+ mRNA as well as in situ hybridization of RNA in single cells revealed that lambda 5 and VpreB are already expressed at the progenitor stage and increase in expression as the progenitors differentiate to precursor (preB) cells, or are turned off as the progenitors differentiate to myeloid cells. Continued rearrangements of Ig genes in pre B cell lines leading to Ig expression on the surface of NFS-5 pre B cells do not influence the continued expression of VpreB and lambda 5. Surface Ig-positive B lineage cell lines also express the pre B-related genes. Both Ly1+ as well as Ly1- pre B cells are VpreB- and lambda 5-positive. Lipopolysaccharide (LPS) stimulation of 70Z/3 pre B cells does not turn off lambda 5 expression. It therefore appears that, at least in transformed cell lines, the expression of VpreB and lambda 5 is not directly regulated by the expression of microH, kappa L, or lambda L chains, LPS reactivity, or the Ly1 surface antigen. Fusion of plasmacytoma cells with normal pre B cells to generate pre B hybridomas leads to down-regulation of VpreB/lambda 5 expression.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Causes and mechanism of autoimmune disease: cyclosporin A as a probe for the investigation.

Organ-specific autoimmune disease can be elicited in rodents by manipulating the thymus/T cells. For example, elimination of a particular T-cell subset causes organ-specific autoimmune diseases, such as thyroiditis and gastritis, in otherwise normal mice. Environmental agents can cause similar autoimmune diseases by affecting the thymus/T cells. Cyclosporin A (CsA), a potent immunosuppressive drug, is an example. When a particular strain of newborn mice are daily administered with CsA for a limited period, they spontaneously develop organ-specific autoimmune disease, such as gastritis with anti-parietal cell autoantibodies, later in life. CsA abrogates the production of CD4+T cells and CD8+T cells in the thymus. Consequently, these T cells are substantially depleted from the peripheral lymphoid organs, especially when the drug is administered from the day of birth. The autoimmune disease is prevented when CsA-treated newborn mice are inoculated with splenic T cells from normal syngeneic adult mice. On the other hand, removal of the thymus immediately after neonatal CsA treatment produces autoimmune disease with a higher incidence and in a wider spectrum of organs, i.e., thyroiditis, sialoadenitis of the salivary gland, gastritis, insulitis of the endocrine pancreas, adrenalitis, oophoritis, or orchitis. Each autoimmune disease is accompanied by the development of circulating autoantibodies specific for the corresponding organ-specific antigens. These findings taken together indicate that CsA causes autoimmune disease not by affecting the target self-antigens, but by interfering with a thymus/T cell-dependent control mechanism on the production/expansion of pathogenic self-reactive T cells. Various other environmental insults (such as ionizing radiation or virus) can also cause similar autoimmune diseases, presumably by a similar mechanism.

Animals↗
PubMed1992

Inhibitory effect of bis(2-aminohexyl) disulfide and bis(2-amino-3-phenylpropyl) disulfide on several mouse inflammations.

The anti-inflammatory profile of the analogues of bis(2-aminopropyl) disulfide dihydrochloride with butyl (compd. II) and phenyl (compd. III) instead of the methyl group was studied in several mouse models related to phagocyte functions. The test samples were administered 2-3 h before the inflammatory stimulation or the peak of inflammation. Subcutaneously administered, compds. II and III significantly inhibited serotonin-induced paw edema in a dose-dependent manner (50% inhibitory dose values: 10 and 5 mg/kg, respectively), when orally administered at 25 mg/kg, these compounds were significantly effective, but their potencies were weaker. Neither compound had any irritant activity when administered at a dose of 12.5 micrograms/5 microliters/paw into the paw. In a sheep red blood cells (SRBC)-induced delayed-type hypersensitivity (DTH) reaction model, compd. II (25 mg/kg, s.c.) significantly inhibited the DTH responses when administered at two different times in relation to the time of challenge. However, there was only slight inhibition by compd. III (25 mg/kg, s.c.) on paw edema formation when administered 14 h after secondary immune response. In a model of experimental acute hepatic failure induced by successive injections of Propionibacterium acnes and lipopolysaccharide, both compounds increased mouse survived, compared with the control mice, and kept the serum levels of components involved in hepatic failure to nearly normal levels. These results demonstrate that compds. II and III possess an inhibitory effect on inflammation related to phagocytes.

Amines↗
PubMed1992

The stimuli releasing histamine from murine bone marrow-derived mast cells (BMMC). 3. Effect of coculture with 3T3 fibroblasts on the histamine releasability of BMMC.

Murine bone marrow-derived mast cells at 3 wk in culture were further cultured in the absence (N-BMMC) or presence (F-BMMC) of 3T3 fibroblasts in the medium containing LI-3, and were examined for their functional responses to either histamine releasing stimuli such as compound 48/80 or an inhibitor of histamine release, disodium cromoglycate. After 3 weeks in coculture with 3T3 fibroblasts, the mast cells increased their histamine content greater than 10 fold, and greater than 10% of the cells changed histochemically to become safranin positive. F-BMMC released approximately 10% histamine when challenged with compound 48/80 or substance P, whereas N-BMMC failed to do so. Furthermore, when the sensitized cells were challenged with DNP-HSA antigen, histamine release from F-BMMC but not from N-BMMC was inhibited by preincubation with disodium cromoglycate. We also examined changes in intracellular Ca2+ ([Ca2+]i) in the cells when challenged with compound 48/80. A transient increase in [Ca2+]i was observed on stimulation with the compound in F-BMMC but not in N-BMMC. Taken together, our results indicate that the interleukin 3-dependent cultured murine mast cells change functionally, as well as histochemically, into in vitro counterparts of connective tissue mast cells when cocultured with 3T3 fibroblasts and may be useful tools for analyzing the mechanisms involved in degranulation from connective tissue-type mast cells.

Animals↗
PubMed1992

[Bacteriological, pharmacokinetic and clinical studies of 5% and 10% granules of cefdinir in the pediatric field].

Bacteriological, pharmacokinetic and clinical studies on cefdinir (CFDN, FK482), a new oral cephalosporin, 5% and 10% granules, were performed in the field of pediatrics. The results are summarized below. 1. Antibacterial activities Antibacterial activities of CFDN against Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, Haemophilus influenzae, Branhamella catarrhalis, Escherichia coli and Klebsiella pneumoniae were studied in comparison with those of cefaclor (CCL), cefixime (CFIX) and amoxicillin (AMPC). MIC80's of CFDN against S. aureus, S. pneumoniae, S. pyogenes, H. influenzae, B. catarrhalis, K. pneumoniae and E. coli were 0.78, 0.20, less than or equal to 0.025, 0.39, 0.10, 0.20 and 0.10 micrograms/ml, respectively. These results show that CFDN has high antibacterial activities against these organisms. MIC80's of CFDN against Gram-positive bacteria were similar to those of AMPC, and was lower than those of CCL and CFIX. As for antibacterial activities against Gram-negative bacteria (GNB), the MIC80 of CFIX against H. influenzae was 0.05 micrograms/ml, which was slightly lower than that of CFDN. THe MIC80's of CFDN against other GNB were similar to those of CFIX. 2. Absorption and excretion Blood concentrations and urinary excretion rates of CFDN 5% and 10% granules and 100 mg capsule were determined. The data on CFDN 10% granules were similar to those on CFDN 5% granules. At a dose of 3 mg/kg, peak blood concentrations (Cmax's) of CFDN ranged from 0.20 to 2.12 micrograms/ml with 5% granules and from 0.50 to 1.15 micrograms/ml with 10% granules at 2 to 3 hours after dosing. At a dose of 6 mg/kg, peak concentrations were 0.66-2.06 micrograms/ml and 0.70-1.52 micrograms/ml with 5% granules and with 10% granules, respectively. At 8 hours after dosing, blood concentrations were 0.04-0.54 micrograms/ml at 3 mg/kg and 0.06-0.27 micrograms/ml at 6 mg/kg. Blood half-lives were 1.33-4.36 hours at 3 mg/kg and 1.14-3.27 hours at 6 mg/kg. AUC's were 1.7-11.0 micrograms.hr/ml with 3 mg/kg and 2.4-8.7 micrograms.hr/ml with 6 mg/kg. With administration of single 100 mg capsule, Cmax's, blood concentrations after 8 hours, T1/2's and AUC's were 0.79-1.88 micrograms/ml, 0.20 micrograms/ml, 1.54-2.72 hours, and 5.2 micrograms.hr/ml, respectively. Urinary recovery rates in the first 8 hours ranged from 6.85 to 39.2% with 3 mg/kg and 6.08-25.5% with 6 mg/kg.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1991

Direct identification of the putative surface IgM receptor-associated molecule encoded by murine B cell-specific mb-1 gene.

The B cell-specific mb-1 gene was recently reported to encode a putative surface glycoprotein with CD3-like structural properties. Hombach et al. suggested and presented evidence to show that this mb-1 gene encodes the 34-kDa membrane glycoprotein (B34 or IgM-alpha) associated with IgMR molecule. To identify the mb-1 gene product directly in B cells, affinity-purified MB-1-specific antibody was prepared by immunization of rabbits with synthetic MB-1 oligopeptide. Immunoprecipitation in combination with two-dimensional diagonal gel electrophoresis analysis revealed that this antibody detected a B cell-specific surface glycoprotein that is very similar to the IgM-alpha (B34) protein described by Hombach et al. However, MB-1 protein exists usually as the monomeric form on the surface of B cells, in contrast to IgM-alpha, which was detected as the dimeric (IgM-alpha/IgM-alpha or IgM-alpha/Ig-beta) protein. We also found that MB-1 protein is already expressed on the sIgM- pre-B cell lymphoma, which might suggest an alternative functional role of this B cell-specific MB-1 protein in B cell differentiation. The molecular identity of MB-1 protein and IgM-alpha (B34) is discussed.

Amino Acid Sequence↗
PubMed1991

Signal transmission through the B cell-specific MB-1 molecule at the pre-B cell stage.

Specific binding of antigens to the surface immunoglobulin M (sIgM) triggers B cells with several biochemical events involved in receptor-mediated signal transmission for proliferation and differentiation into antibody-producing cells. Recent studies with the Digitonin lysis method identified the sIgM-associated component, IgM-alpha (B34)/Ig-beta, as the possible candidate for the transducer molecule(s) in the immunoglobulin receptor-mediated signal transmission. The 34 kd protein (B34 or IgM-alpha) of this component is suggested to be encoded by the B cell-specific mb-1 gene. We prepared monoclonal antibodies which recognize the mb-1 gene product (MB-1) and studied the functional role of MB-1 in the signal transmission in B lineage cells. Using murine pre-B lymphoma cells (18-81 and 70Z/3), we demonstrated the early phase increase of the intracellular [Ca2+]i concentration and the subsequent inhibition of the proliferation by the monoclonal anti-MB-1 antibody (11-18-5). These results clearly demonstrate signal transmission through the surface MB-1 molecule on B lineage lymphomas. This MB-1-mediated signal transmission in pre-B cell lines would suggest an alternative function of MB-1 acting at the pre-B cell stage.

Animals↗
PubMed1991

Extracellular ATP stimulates interleukin-dependent cultured mast cells and eosinophils through calcium mobilization.

We examined the effect of ATP and related nucleotides on the changes in intracellular calcium ([Ca2+]i) in murine bone marrow-derived mast cells (BMMC) and human cord blood-derived eosinophils (EO) cultured in the presence of interleukins. ATP, ADP and AMP released a substantial amount of histamine and leukotriene C4 from BMMC, and EO showed locomotive activity in response to ATP, ADP and GTP. These reactions were accompanied with an increase in [Ca2+]i in BMMC and in EO. The rise in [Ca2+]i in BMMC induced by ATP or antigen at optimal concentrations was inclined to be persisting. On the other hand, these nucleotides induced a rapid and transient rise in [Ca2+]i in EO. Purified human peripheral EO also exhibited locomotive activity and an increase in [Ca2+]i in response to ATP. These results indicate that extracellular ATP activates interleukin-dependent cultured mast cells and EO through Ca2+ mobilization, and suggest that ATP, which is known to be released from activated platelets or autonomic nerves, may stimulate in vivo counterparts of these cultured inflammatory cells.

Adenosine Triphosphate↗
PubMed1991

Changes in filament actin accompanying IgE-dependent and -independent histamine release from IL-3-dependent cultured human basophils.

When cord blood mononuclear cells were cultured in the presence of rhIL-3 for 5 weeks or more, 40-90% of cultured cells became morphologically mature basophils. We analyzed the kinetics of histamine release, changes in filament actin (F-actin), and movement of intracellular Ca2+ ([Ca2+]i) induced by IgE-dependent (anti-IgE) and -independent (fMLP) stimuli in these cultured basophils. Anti-IgE and fMLP released 24.5 +/- 5.4% and 14.5 +/- 4.5% histamine from the cells, respectively. Anti-IgE caused actin polymerization with a peak response at 15 min, which began much later than the elevation of [Ca2+]i. In contrast to anti-IgE stimulation, fMLP induced rapid actin polymerization with a peak response at 30 s in correlation with kinetics of histamine release. Our results indicate that cord blood-derived cultured basophils show similar cell functions to mature basophils, and are useful models with which to investigate the mechanisms of degranulation, specifically when a large amount of highly purified cells are required.

Actins↗
PubMed1991

Biochemical and functional analysis of mixed isotype A beta E alpha class II molecules in Ed alpha transgenic mice.

We demonstrated the existence of mixed isotype A beta E alpha class II molecules in Ed alpha gene-introduced C57BL/6 (B6Ed alpha) transgenic mice. Immunoprecipitation and two dimensional (NEPHGE/SDS-PAGE) gel electrophoresis analysis of labeled B6Ed alpha spleen cell lysates using monoclonal anti-Ab beta antibody showed Ed alpha spots in addition to Ab beta and Ab alpha spots. We obtained alloreactive T cell clones from B6 anti-B6Ed alpha long-term cultures that recognized the Ab beta Ed alpha molecule. We also obtained antigen reactive T cell clones that recognized antigen in the context of Ad beta Ed alpha mixed isotype class II molecules. The importance of the mixed isotype class II molecules in relation to the expansion of the T cell specificity repertoire as well as autoimmune induction is discussed.

Animals↗
PubMed1991

The stimuli releasing histamine from murine bone marrow-derived mast cells. 2. Mechanisms involved in histamine release induced by extracellular ATP and its metabolites.

Extracellular ATP stimulated histamine release and generation of leukotrience C4 (LTC4) accompanied with the formation of inositol phosphates and a rapid increase in intracellular Ca2+ ([Ca2+]i) in mouse bone marrow-derived cultured mast cells (BMMC). The rank order of histamine-releasing potency of ATP and its metabolites is ATP greater than ADP greater than AMP greater than adenosine. Nonhydrolyzable ATP analog, adenosine-5'-O-[2-thiotriphosphate] (ATP-S) released more histamine from the cells than ATP. On the other hand, simultaneous addition of adenosine analogues at micromolar concentrations potentiated histamine release from the cells induced by ATP (50 microM) or DNP-HSA antigen (0.1 ng/ml) in the following rank order: adenosine greater than AMP much greater than ADP = ATP. Histamine release potentiated by adenosine was blocked by the treatment with pertussis toxin, whereas histamine release induced by ATP was not affected by the toxin, suggesting that extracellular ATP stimulate histamine release from BMMC probably via mechanisms independent of the potentiation of histamine release induced by adenosine.

Adenosine↗
PubMed1991

Sialoadenitis in experimental graft-versus-host disease. An animal model of Sjögren's syndrome.

Using light microscopic, immunohistochemical, and ultrastructural techniques, we studied sialoadenitis in mice with chronic graft-versus-host disease (GVHD). To induce chronic GVHD, DBA/2 spleen cells were injected into nonirradiated (C57BL/6 x DBA/2)F1 mice. By light and electron microscopy, the submandibular gland lesion was characterized by mononuclear cell infiltration around the interlobular ducts, often with parenchymal destruction. Immunohistochemically, T cells predominated. The ratio of CD4+ to CD8+ T cells ranged from 1.9:1 to 6:1, with an average of 3.6:1. Lesser numbers of B cells, plasma cells, and macrophages were also present. Histologically, lymphocytic sialoadenitis in chronic GVHD mice was very similar to that reported in patients with chronic GVHD and Sjögren's syndrome.

Animals↗
PubMed1991

[Pharmacokinetic and clinical evaluation of cefpirome in the pediatric field].

We conducted a pharmacokinetic and clinical study on cefpirome (HR 810, CPR), an aminothiazolylmethoxyiminoacetamido cephalosporin (ATOIC), and obtained the following results. 1. Concentrations in blood/excretion in urine. We studied pharmacokinetic in children upon intravenous bolus injections and 30-minute and 1-hour intravenous drip infusions in single dosages of 10, 20, and 40 mg/kg, and obtained virtually the same results as those found in adult subjects. Upon intravenous bolus injections, mean blood concentrations 30 minutes after administration of 10, 20, and 40 mg/kg were 26.1, 47.8, and 82.8 micrograms/ml, respectively, and half-lives were 1.13, 1.43, and 1.26 hours, respectively. Upon 30-minute intravenous drip infusion, mean blood concentrations on completion of the drip infusions of 10, 20, and 40 mg/kg were 43.2, 106.9, and 163.0 micrograms/ml, respectively, and half-lives were 1.15, 1.09, and 1.15 hours, respectively. In addition, upon 1-hour intravenous drip infusion, mean blood concentrations on completion of infusion were 27.1 micrograms/ml for 10 mg/kg and 47.5 micrograms/ml for 20 mg/kg, and half-lives were 1.09 and 1.40 hours, respectively. A clear dose response was observed at all dosages for either administration method. Mean excretion rates in urine in the first 8 hours after administration were 60.6-71.1% upon intravenous bolus injections of 10-40 mg/kg, and upon intravenous drip infusion, the values were 50.2-83.8% for administration of 10-40 mg/kg 6 or 7 hours after completion of drip infusion. 2. Concentrations in the cerebrospinal fluid Penetration into the cerebrospinal fluid was studied in 2 subjects, and a concentration of 0.28-5.19 micrograms/ml was observed upon administration of 50 mg/kg, a moderate degree of penetration compared to the penetration of cephalosporins of group 5 studied up to now. 3. Clinical results Evaluation of clinical effects of CPR on various types of bacterial infections was conducted in 56 subjects, excluding 3 subjects who had diseases which were excluded from the study. The breakdown was as follows: 3 cases of meningitis, 1 case of septicemia, 25 cases of bronchial pneumonia, 1 case each of tonsillitis and infection of the external acoustic meatus, 2 cases each of scarlet fever and phlegmon, 8 cases each of lymphadenitis and urinary tract infections, and 5 cases of staphylococcal scalded skin syndrome. Results of excellent or good were obtained in 54 subjects for an efficacy rate of 96.4%.(ABSTRACT TRUNCATED AT 400 WORDS)

Absorption↗
PubMed1990

Thymus and autoimmunity: capacity of the normal thymus to produce pathogenic self-reactive T cells and conditions required for their induction of autoimmune disease.

BALB/c athymic nu/nu mice spontaneously developed organ-specific (gastritis, thyroiditis, oophoritis, or orchitis) and systemic (arteritis, glomerulonephritis, and polyarthritis) autoimmune diseases when transplanted with neonatal BALB/c thymuses. Transplantation of thymuses from adult BALB/c mice was far less effective in inducing histologically evident organ-specific autoimmune disease in nu/nu mice. Autoimmune disease developed, however, when adult thymuses were irradiated at a T cell-depleting dose before transplantation. Engrafting newborn thymuses into BALB/c mice T cell depleted by thymectomy, irradiation, and bone marrow transplantation produced similar organ-specific autoimmune disease as well, but thymus engrafting into T cell-nondepleted BALB/c mice (i.e., mice thymectomized as adults, but not irradiated) did not, despite the fact that transplanted thymuses grew well in both groups of mice. The mice with organ-specific autoimmune disease produced autoantibodies specific for the respective organ components, such as gastric parietal cells, thyroglobulins, oocytes, or sperm. The thymus-transplanted nu/nu mice also had hypergammaglobulinemia and developed anti-DNA autoantibodies, rheumatoid factors, and immune complexes in the circulation. These results indicate that: (a) the thymus of a murine strain that does not develop spontaneous autoimmune disease can produce pathogenic self-reactive T cells that mediate organ-specific and/or systemic autoimmune diseases; and (b) such self-reactive T cells, especially those mediating organ-specific autoimmune disease, spontaneously expand and cause autoimmune disease when released to the T cell-deficient or -eliminated periphery.

Animals↗
PubMed1990

Structure of the murine mb-1 gene encoding a putative sIgM-associated molecule.

Genomic DNA clones containing the B cell-specific murine mb-1 gene were isolated and a 5.6-kb BamH I fragment was characterized. It is 5629 bp long and contains five exons: an exon containing the 5' untranslated and the coding sequence of the signal peptide, an exon of 294 bp, which contains most of the extracellular sequence of the MB-1 protein, a 119-bp long exon coding mainly for the transmembrane portion, and two exons of 69 bp and 427 bp encoding the cytoplasmic domain and the 3'-untranslated region, respectively. The mb-1 gene does not contain a "TATA box" found in many eukaryotic promoters. The 5'-flanking region has sequence stretches homologous to IgVH 5'-promoter regions and a bcl 2 intron sequence. It contains the decanucleotide sequence (ATGGCAAATA) almost identical to the octamer motif of IgVH promoters. A B cell-specific DNase I-hypersensitive site was found in the 3'-flanking region indicating that this region might be involved in B cell-specific expression of mb-1. Southern blot analysis of genomic liver DNA with the cloned mb-1 cDNA suggests the existence of another mb-1-related gene segment.

Amino Acid Sequence↗
PubMed1990

[Image analysis of morphologic features of the corneal endothelium including hexagonality].

We developed an analysis system for the evaluation of corneal endothelial photographs. Morphological parameters including hexagonality were analyzed semiautomatically with this system. The image analyzer used consists of an image processor MC68000 and image memories 512 x 512 x 17bytes in size. The algorithm that measures the number of apices of each cell is as follows. First, all crossing points of cell borders are detected. Then, each cell is enlarged in order by three pixels in eight directions. The number of crossing points which are overlapped with an enlarged cell is detected as the number of apices of the cell. The analysis time was 7.44 +/- 1.48 min. (mean +/- standard deviation) for 40 endothelial photographs which needed no manual trace for contrast enhancement.

Cell Count↗