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Biomedical subjects

H Uenishi

Publications and source records attributed to H Uenishi.

17 recordsLinked to original sources
PubMed1998

Effect of sulfhydryl oxidoreduction on permeability of cardiac tetrodotoxin-insensitive sodium channel.

Effects of sulfhydryl oxidizing and reducing agents on permeability of the tetrodotoxin (TTX)-insensitive Na-channel were investigated in guinea-pig ventricular myocytes using the whole-cell patch-clamp technique. Mercury chloride (HgCl2) at 1-100 microM irreversibly blocked Na+ currents with no significant changes in the gating kinetics. In contrast, the hydrophilic sulfhydryl oxidizing agent, thimerosal at 50-100 microM little affected Na+ permeation through the Na-channel. The Hg2+-induced block of Na+ current could be readily reversed by 1,4-dithiothreitol (DTT), an agent that reduces disulfide bonds. These results indicate that the formation of sulfur-Hg-sulfur bridge is essential for Hg2+ block. Pretreatment with DTT prevented the Hg2+ block of Na+ current, whereas Zn2+ and Cd2+ retained their abilities to block Na+ current after DTT treatment. An application of Zn2+ or Cd2+ resulted in the restoration of Hg2+ sensitivity of the DTT-treated channel. A conformational model for the Na-channel with multiple free sulfhydryl groups and native disulfide bonds could account for our experimental data regarding the effects of sulfhydryl modifying agents on the channel permeability. We conclude that the cardiac TTX-insensitive Na-channel contains functionally important free sulfhydryl groups and disulfide bonds which are accessible from the extracellular side by an aqueous pathway. These sulfhydryls would be capable of modulating the Na-channel permeability by affecting the conformation of channel pore region.

Algorithms↗
PubMed1998

Overlapping epitopes of friend murine leukemia virus gag-encoded leader sequence recognized by single cytotoxic T-lymphocyte clones.

The leader signal sequence of the non-structural gag-encoded glycoprotein precursor, Pr75gag, of Friend murine leukemia virus (F-MuLV) contains overlapping epitopes, SIVLCCLCL (p71-79) and CCLCLTVFL (p75 83) that activate Friend virus (FV)-induced tumor (FBL-3)-specific cytotoxic T-lymphocytes (CTL) (Kondo et al., J. Virol., 69, 1995, 6735-6741; Chen et al., J. Virol., 70, 1996, 7773-7782). It was investigated whether these two peptides are recognized by a single CTL clone or by individual clones with different specificities. The results show that both hydrophobic and cysteine-containing peptides are bound to H-2Db class I major histocompatibility complex (MHC) molecules and cross-recognized by a single CTL clone as well as bulk-cultured CTL from the spleens of mice immunized with FBL-3. The peptide p71-79 was effective for sensitizing target cells to lysis by CTL in the concentration of common antigenic peptides. Moreover, peptide p75-83 was 1000-fold more potent than the peptide p71-79. Specific cytotoxicity assays with variant peptides with alanine- and serine-substitutions suggested a highly complex function of the disulfide bond-forming peptides potentially sensitive to small sequence differences. The dominance of CTL responses to the transmembrane region is discussed in light of the high affinity of a novel hydrophobic peptide to compete with other peptides for binding to MHC molecules.

Amino Acid Sequence↗
PubMed1998

Induction of cross-reactivity in an endogenous viral peptide non-reactive to FBL-3 tumor-specific helper T-cell clones.

We previously reported a helper T-cell (Th) epitope (peptide i) which corresponded to the sequence ranging from positions 462 to 479 from the N-terminus of the Friend-murine leukemia virus (F-MuLV) envelope protein (env462-479). Homologous sequences exist in both Moloney-murine leukemia (M-MuLV env452-469) and endogenous AKV (AKV env453-470) viruses, which differ from F-MuLV env462-479 in 5 and 7 amino acids, respectively. However, peptide i-specific Th clones did not respond to either of the corresponding exogenous or endogenous peptides. One amino acid substitution in M-MuLV env452-469 (Asn to Tyr at position 465: N465Y) and three amino acids in AKV env453-470 (H460S, A466Y and Y468H) endowed both peptides with the reactivity to one of the Th clones, F5-5, almost to the same degree as peptide i. However, the other Th clones responded differently to each of the modified endogenous peptides substituted by one to three amino acids. The cells responsive to the cross-reactive peptides occupied only a minor portion, if any, of the bulk cultured lymph node cells from peptide i-immune mice, and in particular, no significant response to the modified endogenous peptides was observed in repeated experiments. The exchange of at least 3 residues was necessary for the endogenous peptide to acquire sufficient cross-reactivity to two of the three Th clones. However, it was noticeable that a single substitution of alanine by tyrosine at the dominant T-cell receptor (TCR) contact position of the peptide i(e) generated a weak but significant cross-reactivity to one of the three Th clones in this study. Thus, peptides of endogenous retroviral origin that would be modified by mutational events might become 'non-self' and prime Th cells leading to auto-antibody production and resulting in autoimmune disease.

Amino Acid Sequence↗
PubMed1995

Immunization with a single T helper cell epitope abrogates Friend virus-induced early erythroid proliferation and prevents late leukemia development.

Synthetic peptide vaccines containing a single Th cell epitope identified in the gp70 envelope glycoprotein of Friend murine leukemia helper virus induced potent protective immunity against Friend virus infection. H-2a/b mice immunized by a single s.c. injection of the CFA emulsion containing a peptide that represented the N-terminal gp70 epitope recovered slowly from initial development of splenomegaly, and most did not develop late leukemia, whereas most of the control mice given an injection of CFA alone showed sustained leukemic splenomegaly after the challenge with Friend virus. The mice of the same genetic background immunized with the C-terminal Th cell epitope by a single injection of a separate synthetic peptide eliminated virus-producing cells from the spleen within 12 days after inoculation of Friend virus complex, and did not develop early splenomegaly or polycythemia. H-2a/a mice were not protected by immunization with either one of the two synthetic peptides. Earlier production and more rapid class switching of virus-neutralizing Abs were observed in H-2a/b mice immunized with the peptide vaccines after the challenge with Friend virus, compared with the responses of the control mice. Detailed kinetic and immunohistopathologic analyses suggested that Th cells might be directly involved in the growth inhibition and elimination of virus-infected erythroid precursor cells.

Amino Acid Sequence↗
PubMed1995

A single retroviral gag precursor signal peptide recognized by FBL-3 tumor-specific cytotoxic T lymphocytes.

Several dominant T-cell receptors of cytotoxic T-lymphocyte (CTL) clones specific for FBL-3 tumor antigen were clonally amplified in mixed lymphocyte tumor cell cultures derived from an individual immune mouse. Every CTL clone analyzed had a common specificity for a single epitope in the precursor to cell membrane-associated nonstructural gag-encoded protein, Pr75gag, which can be minimally identified by nine amino acid residues, SIVLCCLCL. This epitope is located within the hydrophobic signal sequence motif that mediates translocation of the protein into the endoplasmic reticulum. These novel observations suggest that expression of Pr75gag in FBL-3 tumor cells led to the amplification of CTLs which recognize the signal sequence of the nonstructural gag-encoded glycoprotein precursor.

Amino Acid Sequence↗
PubMed1994

Fine structure of a virus-encoded helper T-cell epitope expressed on FBL-3 tumor cells.

Antigen peptide fn20 representing Friend murine leukemia virus env122-141 (DEPLTSLTPRCNTAWNRLKL) is recognized by two independent Friend virus-induced, FBL-3 tumor-specific helper T-cell (Th) clones. We isolated more Th clones from mice immunized with fn20 peptide. We examined the fine structure of the peptide required to activate a large group of fn20-specific Th clones. A systematic analysis of peptides of decreasing lengths eliciting Th proliferation defined the minimum core length as 13 amino acids (LTSLTPRCNTAWN). Functional proliferation and competition assays with variant peptides with alanine substitutions permitted the assignment of five peptide residues in two major histocompatibility complex-interacting and three T-cell-receptor-interacting sites. Th clones were different in their reactivities toward peptides of various lengths and the variant peptides.

Amino Acid Sequence↗
PubMed1993

Disseminated intravascular coagulation in a patient with acute myeloid leukemia. Ultrastructural evidence of hypercoagulation in bone marrow.

The bone marrow of a 53-year-old woman with acute myeloid leukemia (AML) with disseminated intravascular coagulation was investigated by transmission electron microscopy. The patient had a preceding granulocytic sarcoma, and subclinical disseminated intravascular coagulation occurred concomitantly with the development of AML. Ultrastructural findings of the bone marrow at the onset of AML revealed the following: (1) The cytoplasm of the leukemic cells showed frequent fragmentation, resulting in the formation of abundant cytoplasmic fragments. (2) These cytoplasmic fragments were surrounded by abundant fibrin fibers, forming the fibrin-cytoplasmic fragment complex (FCF complex). (3) Slight fibrin deposition was seen around the leukemic cells and in the intercellular space of the bone marrow. Fibrin deposition in the bone marrow is thought to represent morphologic evidence of disseminated intravascular coagulation. The damage on the leukemic cell surface due to the cytoplasmic fragmentation seems to be closely related to the development of disseminated intravascular coagulation.

Acute Disease↗
PubMed1992

Medial longitudinal fasciculus syndrome associated with a subdural hygroma and an arachnoid cyst in the middle cranial fossa.

A 60-year-old man complaining of diplopia and vertigo showed bilateral medial longitudinal fasciculus (MLF) syndrome. The CT scan revealed a space-occupying lesion with watery fluid in the left cranial fossa, which was divided into two parts by a thin septum. Surgical trepanation was performed followed by 4 weeks of prednisolone therapy. He was completely cured 5 months later. The plausible causes of MLF syndrome relevant to preexisting space-occupying lesions are discussed.

Arachnoid Cysts↗
PubMed1991

[The inhibitory effect of oxatomide on oxygen radical products from human eosinophils and an eosinophilic cell line].

Recently, much attention has been paid to the role played by the allergic inflammatory reaction in the role of asthma. Eosinophils are considered to be major inflammatory cells in bronchial asthma. Therefore, in this study, eosinophil-mediated oxygen radicals were examined by means of luminol-dependent chemiluminescence. Also, the effect of oxatomide, an anti-allergic agent, which has an inhibitory effect on eosinophil-mediated natural cytotoxicity against bronchial epithelial cells, on the production of oxygen radicals from eosinophils was studied. The results revealed the inhibitory effects of oxatomide on eosinophil-mediated oxygen radicals products. Furthermore, the inhibitory effect of this agent on oxygen radical products from eosinophilic cell-line named EoL-3, which has been established recently, was observed. We concluded from these results that oxatomide not only has anti-allergic activity but also anti-inflammatory properties for eosinophils.

Anti-Inflammatory Agents↗
PubMed1991

Induction of IgE-Fc receptor (Fc epsilon R2/CD23) expression on lymphocytes from patients with mite-allergic bronchial asthma by mite allergen.

The present study was designed to clarify whether Fc epsilon R2 can be induced on lymphocytes of patients with bronchial asthma by stimulation with specific antigen. Expression of Fc epsilon R2 on freshly isolated lymphocytes (at 0 hour) was significantly higher in both patients with mite-allergic asthma and those with nonmite-atopic asthma than in healthy individuals. In addition, expression of Fc epsilon R2 on lymphocytes was still higher in patients during acute asthma. Marked induction of Fc epsilon R2 on lymphocytes was observed 48 hours or more after addition of mite-allergen in patients with mite-allergic asthma while no Fc epsilon R2 expression was induced in patients with nonmite-atopic asthma or healthy individuals. Induction of Fc epsilon R2 expression was not observed at 30 minutes, two hours, and five hours, which are equivalent in kinetics to immediate asthmatic response and late asthmatic response in allergen inhalational challenges.

Allergens↗
PubMed1989

[The inhibitory effect of oxatomide, an anti-allergic agent, on eosinophil-mediated and eosinophilic cell line-mediated natural cytotoxicity against bronchial epithelial cells].

Recently, eosinophils have been implicated as inflammatory effector cells in allergic and inflammatory reactions such as bronchial asthma. In this study eosinophil-mediated and eosinophilic cell line-mediated natural cytotoxicity against bronchial epithelial cells and the effects of oxatomide, an anti-allergic agent, on their cytotoxicity were investigated. Treatment with oxatomide diminished both eosinophil-mediated and eosinophilic cell line-mediated natural cytotoxicity in vitro. We concluded from these results that oxatomide not only has anti-allergic activity but also anti-inflammatory properties for eosinophils. In addition this method for isolating eosinophils seems to well serve the purpose of evaluating eosinophil function as in this investigation, as we have reported previously.

Bronchi↗