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Biomedical subjects

N Sakaguchi

Publications and source records attributed to N Sakaguchi.

At least 109 records · Page 6Linked to original sources
PubMed1994

Growth in methylcellulose of human mast cells in hematopoietic colonies stimulated by steel factor, a c-kit ligand.

We examined the effect of Steel factor (SLF) on the development of human mast cells in hematopoietic colonies from cord blood mononuclear cells in methylcellulose culture. When cord blood cells were cultured for 3 weeks, SLF increased the cellular tryptase levels detected in total cultured cells. It also stimulated the formation of small-cell colonies consisting mainly of polymorphonuclear granulocytes and immature blastoid cells in a concentration-dependent manner but not the formation of colonies consisting of large macrophagic cells. A low percentage of tryptase-positive mast-cell-like cells was found in 39 out of 100 granulocyte/blastoid cell colonies. Four of the 100 colonies contained 10-20% tryptase-positive cells, but we failed to observe colonies consisting of > 20% of tryptase-positive cells. These results suggest that the effect of SLF on mast cell growth is brought on by stimulating the growth of primitive hematopoietic progenitors.

Cell Adhesion Molecules↗
PubMed1994

Helminth survey of wildcats in Japan.

Two Iriomote cats (Felis iriomotensis) and 2 Tsushima leopard cats (Felis bengalensis euptilura) killed probably by traffic accidents were submitted to the helminthological examination. In Iriomote cats, 8 species of parasites (Spirometra erinacei, Toxocara cati, Molineus springsmithi, Uncinaria maya, Capillaria aerophila, C. felis-cati, larvae of an unidentifiable lung worm and one species of Acanthocephala) were found. In Tsushima leopard cats, 10 species of parasites (Pharyngostomum cordatum, Spirometra erinacei, Toxocara cati, Molineus springsmithi, Arthrostoma hunanensis, Uncinaria felidis, Capillaria felis-cati, larvae of an unidentifiable lung worm, and two species of Acanthocephala) were detected.

Animals↗
PubMed1994

[Adrenocortical function in children with near fatal asthma].

The adrenal function of children with near fatal asthma was evaluated by a modified rapid ACTH test. The rapid ACTH tests, which were performed within six months of each life-threatening asthmatic episode, showed extremely low responsiveness. The response in the subjects was significantly lower than that of patients who had received high dose of corticosteroid therapy. It was suggested that the adrenocortical function of children with near fatal asthma had been already suppressed and that adrenal suppression could easily occur in such patients. We advocate the following measures: (1) environmental control, education of patients and their families, physical training accurate medication should be supplied to reduce the use of corticosteroids, (2) sufficient doses of corticosteroids should, however be given to patients with acute exacerbation, (3) not only lung function tests or allergic examinations, but also adrenocortical function tests should be performed on severe asthmatic patients.

Adolescent↗
PubMed1994

[A comparative evaluation of three commercially available peak flowmeters before and after being used 1000 times].

The differences in values, accuracy, reproducibility and interdevice variability of three models of portable peak flowmeters (standard and low range of Assess, mini-Wright, Pulmo-Graph) before use and after they had been used 1000 times. A computerized standard flow generator was used to evaluate. Standard range; The three models showed differences in values before and after 100 uses of less than 3 percent at flow rates below 480 L/min. However, the used flowmeters, especially the Assess, showed higher values compared with the new ones at higher flow ranges. There was no significant difference in accuracy between the new and used mini-Wright and Pulmo-Graph models. The used Assess, howevers, showed higher values at higher ranges, thus demonstrating improved accuracy over the new ones. The reproducibilities of the three models deteriorated at high flow rates. The interdevice variability of the used Pulmo-Graph flowmeter was better than that the new one. No significant changes were observed in the mini-Wright, while the Assess showed deteriorated interdevice variability. Low range; The three models showed no significant differences in values, accuracy, reproducibility or interdevice variability before and after use.

Evaluation Studies as Topic↗
PubMed1994

[An evaluation of three commercially available peak flowmeters].

The accuracy, reproducibility and interdevice variability of three models of portable peak flowmeters (standard and low range) were evaluated by using a computerized standard flow generator. Standard range; The mini-Wright peak flow meter generally overestimated peak flow from 120 L/min to 540 L/min and the Assess peak flowmeter underestimated peak flow at full range. The Pulmo-Graph peak flowmeter showed a similar pattern to the mini-Wright but with more accuracy. The Assess showed the best linearity. The reproducibilities of the three models deteriorated over 20 L/min at high flow rates. The interdevice variability of the mini-Wright was better than those of the Assess or the Pulmo-Graph. Low range: The accuracy and interdevice variability of the Pulmo-Graph were better than those of the Assess or the mini-Wright. The reproducibility of Assess seemed to be inferior to the other's. The measured flow from the low ranges was not the same as that of the standard ranges. The three peak flowmeter models have different spring mechanisms for their readings, and the measured flows by one model should not be compared with other models.

Evaluation Studies as Topic↗
PubMed1993

Induction of tyrosine phosphorylation in human B lineage cells by crosslinking MB-1 molecule of B cell receptor-related heterodimer complex.

B cell antigen receptor is composed of immunoglobulin and associated MB-1 and B29. Here, we found that anti-human MB-1 stimulation induced tyrosine phosphorylation in immature B cells (FL4.4 and Nalm-6) but not in mature B cells (Daudi). Coprecipitated complex with the heterodimer component in Daudi and Nalm-6 contained the kinase molecule(s) which act on the heterodimer protein, while the complex in early lymphoid cell with germ line antigen receptor genes (FL4.4) did not. Candidate Fyn and Lyn are expressed in Nalm-6 and Daudi but are not expressed in FL4.4. These results suggested that src-type tyrosine kinases as Fyn and Lyn are responsible for the phosphorylation of MB-1 and B29 heterodimer, but anti-MB-1 stimulation can induce tyrosine phosphorylation reaction mediated by other kinase molecule(s) in the progenitor type cells.

Amino Acid Sequence↗
PubMed1993

Cross-linking of B cell receptor-related MB-1 molecule induces protein tyrosine phosphorylation in early B lineage cells.

Cross-linking of surface B cell Ag receptor (BCR) induces tyrosine phosphorylation of BCR-associated components through a receptor-mediated signal transmission pathway. B cell-specific mb-1 and B29 genes encode the alpha/beta components of the BCR-associated complex in mature sIgM+ B cells. Here, we studied the involvement of the mb-1 gene product, MB-1, in the BCR-related structure of immature B cells. Affinity-purified anti-MB-1 antibody coprecipitated mu chain/20-kDa/15-kDa proteins together with monomer MB-1 and Ig-alpha/Ig-beta heterodimer components from digitonin lysates of the pre-B cell line 18.81. The monomer MB-1 and Ig-alpha in the pre-B cell line were shown to migrate with identical patterns in nonequilibrium pH gradient gel electrophoresis/SDS-PAGE. Western blot analysis showed that MB-1 protein is coprecipitated with mu chain from the pre-B cell line. We studied the tyrosine phosphorylation response of bone marrow B lineage cells as well as spleen B cells after cross-linking of BCR-related components with anti-mu, anti-kappa, and anti-MB-1 antibodies. We identified the activation of tyrosine kinase by direct cross-linking of MB-1 expressed on the surface of early B lineage cells. Anti-mu antibody stimulation induced the activation of tyrosine kinase in early (5- to 10-min) and late (30- to 120-min) responses in bone marrow early B lineage cells. Anti-MB-1 mAb (11-18-5) induced the late response exclusively but anti-kappa antibody induced only the early response. These results clearly indicate that MB-1 acts in the BCR-mediated signal transmission in early B lineage cells. To explore the molecular mechanism of protein tyrosine phosphorylation in bone marrow B lineage cells, we studied associated components of the BCR complex by using an in vitro kinase reaction and observed the phosphorylation of a 60-kDa protein in pre-B cell lines. The 60-kDa phosphoprotein coprecipitated with MB-1 and the BCR-related complex is very similar to the Src-type Fyn tyrosine kinase or a Fyn-related protein.

Animals↗
PubMed1993

Multiple B29 containing complexes on murine B lymphocytes. Common and stage-restricted Ig-associated polypeptide chains.

The B29 gene is specifically expressed in all cells of the B lymphocyte lineage, and the B29 protein is disulfide-linked to the protein product of at least one other gene, known as mb-1. The noncovalent association of these heterodimers with Ig H chains is thought to be required for surface expression and signal transmission by B cell Ag receptors. We now demonstrate by two-color immunofluorescence a direct correlation between B29 density and surface Ig expression on normal spleen and bone marrow cells. The proportion of B29 in Ag receptor complexes appears to be relatively constant across major B lymphocyte subpopulations. Multiple B29-containing heterodimers were resolved on normal spleen cells by surface labeling, immunoprecipitation, two-dimensional gel analysis, and immunoblotting. As with lymphoma cells in our earlier study, the conditions of detergent extraction were critical to detection of certain species. Many laboratories have observed a family of 69- to 85-kDa heterodimers that are extracted with digitonin. These species are clearly Ig-associated, and are coprecipitated with anti-Ig antibodies. We found that extraction with Triton X-100 revealed an additional pair of 52- to 58-kDa heterodimers, where B29 was disulfide-bonded to a protein of approximately 23 kDa. The latter was detectable by immunoblotting with antibodies to extracellular, but not cytoplasmic, portions of mb-1. We found that, with mature cells, both conventional and low molecular mass heterodimers were solubilized with digitonin, but only detectable if Triton was present during immunoprecipitation. Thus, a protein having partial serologic identity with mb-1 forms heterodimers that are cryptic on splenic B cells, and possibly not directly associated with surface Ig molecules. In contrast, both types of heterodimers were readily detectable on late stage pre-B cells, regardless of detergent used for extraction or antibody used for immunoprecipitation. In that situation, both low- and high molecular mass heterodimers were associated with surface Ig. These findings increase our understanding of the B lymphocyte Ag receptor complex and indicate that its components may change as a function of differentiation.

Animals↗
PubMed1993

Ultrastructural study of Cryptococcus neoformans by quick-freezing and deep-etching method.

The three-dimensional ultrastructure of Cryptococcus neoformans was studied by quick-freezing and deep-etching (QF-DE) method. C. neoformans, strain CDC551, was cultured on agar. The viable yeast cells (10(7) cells) were inoculated into each mouse from the tail vein. Three weeks after the inoculation, the brains of the mice were perfused with fixatives, quickly frozen, freeze-fractured, deeply etched and rotary shadowed with platinum and carbon. In addition, the viable cells of C. neoformans on agar were picked up and quickly frozen, and replica membranes were prepared as described above. The ultrastructure of C. neoformans was three-dimensionally demonstrated by the QF-DE method. The capsule was composed of fine meshworks of microfibrils (10-13 nm in diameter), which were directly attached to the cell walls. The capsule of the in vivo yeasts (yeast cells in the brain lesion) was thicker than that of the in vitro yeasts (yeast cells on agar culture). At the outer part of the cell wall, a particle-accumulating layer was observed. This layer in vivo was thicker than that in vitro. Occasionally, the yeast cells were ingested by phagocytes in the mouse brain. Although the cytoplasm of such yeast cells was destroyed, the capsular meshworks were well preserved. The ultrastructure of the capsule was the same both in cultured and phagocytized yeasts in the cystic lesions of the brains. This lack of morphological changes of the capsular meshworks suggests that they are resistant to the digestion by phagocytes. This stability of capsular structures may provide one of the important pathogenic factors in cystic lesions by C. neoformans.

Animals↗
PubMed1993

Ultrastructural study of hepatic granulomas induced by Cryptococcus neoformans by quick-freezing and deep-etching method.

The ultrastructure of hepatic granulomas induced by Cryptococcus (C.) neoformans was studied by a quick-freezing and deep-etching (QF-DE) method. Viable yeast cells were inoculated intravenously into rats and the livers were prepared for QF-DE replicas. Two cytoskeletal components were identified in the cytoplasm of macrophages composing the cryptococcal granulomas. These were: intermediate filaments, mainly located in the perinuclear region, and actin filaments, which were extensively decorated with myosin subfragment 1 (S1) and formed networks in the peripheral portion of the cytoplasm. In addition, two types of macrophage pseudopodia were observed in the granulomas. These were cobble stone-like pseudopodia at the yeast-macrophages contract areas, and thin, long and occasionally interdigitating pseudopodia in which actin filaments were consistently observed. Dense networks of actin filaments were also seen in pseudopodia protruding into the tight structure of the capsule of C. neoformans. These results suggest a role for actin filaments as one of the main factors in the force generating system of the phagocytic process.

Animals↗
PubMed1993

The surrogate light chain in B-cell development.

The proteins encoded by the VpreB and lambda 5 genes associate with each other to form a light (L) chain-like structure, the surrogate L chain. It can form Ig-like complexes with three partners-the classical heavy (H) chain, the DHJHC mu-protein, or the newly discovered p55 chain; these are expressed on the surface of pre-B cells at different stages of development. Here, Fritz Melchers and colleagues review the structures of the VpreB and lambda 5 genes in mouse and their relatives in humans, describe their pattern of expression, and speculate on their possible evolution and functions.

Amino Acid Sequence↗
PubMed1993

Incidence of latex allergy in atopic children and hospital workers in Japan.

The incidence of latex-induced allergy has been reported to be increasing in Europe and the US but not in Japan. We thus measured latex-specific IgE antibodies and latex-specific IgG antibodies in sera from 196 atopic children with low serum IgE levels (under 1,000 U/ml; group 1), 108 atopic children with high serum IgE levels (over 1,000 U/ml; group 2) and 601 hospital employees (group 3). Atopic children were diagnosed as having asthma, atopic dermatitis and/or food intolerance. One out of group 1 (0.5%) and 11 out of group 2 (10.2%) were found to have latex-specific IgE by radioallergosorbent assay (RAST), and 7 were further found to be positive for latex antigen by skin test. Fifty-five percent of group 1, 65% of group 2 and 9.7% of group 3 were found to have latex-specific IgG over 100 units/ml by enzyme linked immunosorbent assay (ELISA). Prior to our diagnosis most of the children and employees did not realize they were allergic to latex. These data suggest that caution should be taken regarding latex allergy when atopic children have to be operated upon as atopic children tend to be sensitized to the latex antigen after even minimal contact with latex products.

Adolescent↗
PubMed1993

Incidence of latex allergy in atopic children in Japan.

Many cases of latex-induced intraoperatived anaphylaxis have been reported in Europe and the U.S. but not in Japan. We measured latex-specific IgE antibody in sera from the 108 atopic children with high serum IgE levels (over 1,000 U/ml). All of them were diagnosed to have asthma, atopic dermatitis and/or food intolerance. Eleven (10.2%) out of 108 patients were found to have latex-specific IgE by RAST, and 6 of them were positive for latex antigen by skin test. Most of the children did not realize that they were allergic to latex until we discovered it. This data suggest that we should be cautious about latex allergy when atopic children have to be operated upon.

Adolescent↗
PubMed1992

Identification of IL-7-dependent bone marrow-derived Thy-1-B220- lymphoid cell clones that rearrange and express both Ig and T cell receptor genes.

Bone marrow stromal cell lines and lymphoid cell lines were co-established from the Whitlock-Witte type of long term liquid cultures of MRL/1 and C57BL/10 (B10) (Thy-1.1) bone marrow cells. The present study investigates the immunologic nature of parental and cloned lymphoid cell lines. Both strains of parental lines and their clones did not grow alone but proliferated on the monolayers of co-established parental stromal cell lines from a syngeneic or alternative strain. When various lymphokines or cytokines were tested for their capacity to support the growth of these lymphoid cell clones, only IL-7 could substitute for the growth-promoting function of stromal cells. These IL-7-dependent clones expressed neither Thy-1 nor B220 Ag. However, all of them from two strains were found to rearrange synchronously H chain of Ig as well as gamma chain of TCR genes. Some of the clones transcribed a mature size of IgH mRNA. Co-expression of mRNA for lambda 5 but not for IgL chain (kappa, lambda) genes resulted in the generation of cell surface mu chain in these clones. Other clones expressed a smaller size of IgH mRNA without exhibiting surface mu chain. Irrespective of the differences in IgH rearrangements and its mRNA expression, a mature size TCR gamma mRNA was detected in all of the clones. Thus, these results demonstrate the existence of untransformed (IL-7-dependent) immature lymphoid cells rearranging both Ig and TCR genes. Their unique features concerning cell surface markers (B220- mu+), specific growth factor requirement, and various modes of Ig/TCR gene rearrangements are discussed in the context of early lymphoid development.

Animals↗
PubMed1992

Three-dimensional study of epithelioid cells by a quick-freezing and deep-etching method in muramyl dipeptide-induced granulomas.

The three-dimensional ultrastructure of epithelioid cells was studied by the quick-freezing and deep-etching (QF-DE), as well as the freeze-substitution (QF-FS) methods. The granulomas were induced in rats by injecting muramyl dipeptide (MDP) into the hind footpads. At 3 weeks after the injection, the footpads were perfused with a fixative, excised, and quickly frozen to prepare the replica membranes. Some unfixed footpads were also quickly frozen and freeze-substituted. Dense networks of intermediate filaments, connected with the nuclei, mitochondria and other vesicular cell organelles, were observed throughout the cytoplasm of epithelioid cells by the QF-DE method. A few actin filaments were located in filopodia and just beneath the cell membranes. Interdigitation of the cell membranes between adjacent cells was clearly demonstrated by the QF-FS method and clathrin-coated pits were identified at the base of interdigitating filopodia. In addition, the exact moment of fusion between endosomes and lysosomes was ascertained by the same method. These results suggest that the cytoskeletal organization of epithelioid cells resembles that of epithelial cells rather than actively motile macrophages.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1992

Establishment of a murine pre-B cell clone dependent on interleukin-7 and stem cell factor.

To identify cytokines required for proliferation of murine pre-B cells, we established a pre-B cell clone MH11 (B220+ MB-1+ sIgM-) on a stromal cell line ST2 from day 13 fetal liver. The growth of MH11 is dependent on ST2. Another stromal cell line PA6, non-secretor of IL-7, could not support MH11 unless IL-7 was added. We investigated the effect of cytokines on proliferation of MH11 with or without stromal cells. IL-7 had a stimulatory effect on proliferation of MH11, but IL-7 alone could not support MH11 growth without ST2. Recombinant stem cell factor (rSCF) also had a positive effect on MH11. rSCF and rIL-7, when added together, could maintain the growth of MH11 in the absence of stromal cells. Moreover, the growth of MH11 on ST2 was inhibited almost completely by anti-c-kit monoclonal antibody (mAb). These results demonstrate that direct SCF/c-kit interaction is involved in the stimulation of pre-B cells.

Animals↗