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Y Kohno

Publications and source records attributed to Y Kohno.

At least 127 records · Page 7Linked to original sources
PubMed1997

Short-homology-independent illegitimate recombination in Escherichia coli: distinct mechanism from short-homology-dependent illegitimate recombination.

We have shown elsewhere that there is no, or very little, homology at the recombination sites in DNA gyrase-mediated illegitimate recombination in vitro. On the other hand, many reports have indicated that illegitimate recombination takes place between sequences with a short homology. To clarify this contradiction, we analyzed the mechanism of DNA gyrase-mediated illegitimate recombination in vivo, by isolating a temperature-sensitive gyrA mutant (gyrAhr1) that causes spontaneous illegitimate recombination at a higher frequency than that of the wild-type. This mutant also causes spontaneous induction of lambda prophage. It is therefore suggested that the gyrAhr1 mutation induces strand breaks in the chromosome, resulting in the formation of illegitimate recombinants. Analysis of the recombination junctions of lambdabio transducing phages formed spontaneously in the gyrAhr1 mutant revealed that the Escherichia coli bio and lambda recombination sites have an average homologous sequence of only 1.3 base pairs. This is the first indication that homology in vivo is not required for illegitimate recombination. On the other hand, a short homology of 8.4 bp, on average, was found in the junctions of lambdabio transducing phages formed spontaneously in the wild-type bacteria. When the gyrAhr1 mutant was irradiated with UV, short homologies were also detected in the junctions. We concluded that illegitimate recombination, which takes place spontaneously in the gyrAhr1 mutants, is distinguishable from spontaneous recombination in the wild-type and from UV-induced recombination in the mutant with regard to the requirement for short homology. We propose that short-homology-independent illegitimate recombination is mediated by subunit exchange between DNA gyrase, while short-homology-dependent recombination is triggered by double-strand breaks and completed by processing, annealing, and ligation of DNA ends.

Bacteriophage lambda↗
PubMed1997

Anti-tremor activity of talipexole produced by selective dopamine D2 receptor stimulation in cynomolgus monkeys with unilateral lesions in the ventromedial tegmentum.

The anti-tremor activity of talipexole (6-allyl-2-amino-5,6,7,8-tetrahydro-4H-thiazolo[4,5-d]azepine dihydrochloride, B-HT 920 CL2, Domin), a non-ergot dopamine D2 receptor agonist which possesses alpha 2-adrenoceptor agonistic and 5-HT3 receptor antagonistic properties, was examined in monkeys with a unilateral lesion in the ventromedial tegmentum. Talipexole dose dependently suppressed the tremor and had ED50 values of 34 micrograms/kg s.c. and 84 micrograms/kg p.o. The anti-tremor effect of talipexole occurred at much lower doses than that of an ergot dopamine receptor agonist, bromocriptine (2-bromo-alpha-ergocryptine mesilate, ED50; 2.5 mg/kg s.c.), and talipexole acted synergistically in combination with L-DOPA (3,4-dihydroxyphenylalanine). In ventromedial tegmentum-lesioned monkeys, anti-tremor doses of talipexole did not cause emetic behavior, but had sedative effects. Conversely, monkeys given bromocriptine exhibited oral movement, salivation and vomiting when anti-tremor effects were observed, but not marked sedative behavior at any of the doses investigated. During repeated administration of talipexole (a daily dose of 50 micrograms/kg s.c. for 21 days), the extent and duration of the anti-tremor effect did not change, but those of the sedative effect decreased gradually. The anti-tremor effect of talipexole was significantly suppressed by sulpiride, but not by SCH 23390 (7-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7-ol) or yohimbine, while the sedative effect was inhibited by sulpiride and yohimbine. The main metabolites of talipexole had no anti-tremor or sedative effects. These results indicate that talipexole exerts its anti-tremor activity via selective dopamine D2 receptor stimulation.

Administration, Oral↗
PubMed1997

Mechanistic studies on metabolic chiral inversion of 4-(4-methylphenyl)-2-methylthiomethyl-4-oxobutanoic acid (KE-748), an active metabolite of the new anti-rheumatic agent 2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid (KE-298), in rats.

The chiral inversion properties of 4-(4-methylphenyl)-2-methylthiomethyl-4-oxobutanoic acid (KE-748), an active metabolite of 2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid (KE-298), were compared with those of ibuprofen in rats. After administration of R(-)-[2 alpha-2H]KE-748, S(+)-KE-748 was present in the rat plasma, and the deuterium atoms of the S(+)-enantiomer were almost all replaced by hydrogen atoms. After administration of S(+)-[2 alpha-2H]KE-748, the deuterium content of S(+)-KE-748 in the plasma remained intact. In the in vitro study, using a cell-free system and rat liver homogenates, the chiral inversion of ibuprofen was apparent when both CoA and ATP were present; however, KE-748 was not inverted. In the study on isolated rat hepatocytes, the unidirectional chiral inversion from R(-)-to S(+)-enantiomer was observed for both ibuprofen and KE-748. When R(-)-ibuprofen was incubated with medium and long chain fatty acids (carbon chain length C6 to C16), using isolated hepatocytes, the chiral inversion decreased significantly. On the other hand, when R(-)-KE-748 was incubated with short and medium chain fatty acids (carbon chain length C3 to C8), chiral inversion was inhibited markedly. To induce hepatic microsomal long chain fatty acid CoA ligase, rats were treated with clofibric acid (CF rats). In both in vitro and in vivo experiments on CF rats, chiral inversion from R(-)-to S(+)-ibuprofen was enhanced significantly compared with that in controls, whereas the enhancement was not observed in the case of R(-)-KE-748. There was no influence of benzoic acid, a typical substrate on medium chain fatty acid CoA ligase in the mitochondrial matrix, on chiral inversion of R(-)-ibuprofen, using, isolated hepatocytes. In contrast, the chiral inversion from R(-)-to S(+)-KE-748 was strongly inhibited in the presence of benzoic acid. These results indicate that chiral inversion of R(-)-KE-748 may proceed via formation of the CoA-thioester intermediate with loss of the 2 alpha-methine proton, in a manner similar to that seem with R(-)-ibuprofen. However, the enzymes needed to form CoA-thioester of R(-)-KE-748 differ from those for R(-)-ibuprofen.

Animals↗
PubMed1997

Stereoselective disposition and chiral inversion of KE-298, a new antirheumatic drug, in rats.

The present study was an attempt to elucidate the relationship between stereoselective pharmacokinetics and protein binding of KE-298 and its active metabolites, deacetyl-KE-298 (M-1) and S-methyl-KE-298 (M-2). Metabolic chiral inversion was also investigated. The levels of unchanged KE-298 in plasma after oral administration of (+)-(S)-KE-298 to rats were lower than those of (-)-(R)-KE-298, whereas the levels of M-1 and M-2 after administration of (+)-(S)-KE-298 were higher than after (-)-(R)-KE-298. In vitro, rat plasma protein binding of (+)-(S)-KE-298 was lower than that of (-)-(R)-KE-298. In contrast, the binding of (+)-(S)-M-1 and (+)-(S)-M-2 was higher than that of (-)-(R)-M-1 and (-)-(R)-M-2. Displacement studies revealed that the (+)-(S) and (-)-(R)- enantiomers of KE-298 and their metabolites bound to the warfarin binding site on rat serum albumin. These results suggested that the stereoselective plasma levels in KE-298 and its metabolites were closely related to enantiomeric differences in protein binding attributed to quantitative differences in binding to albumin rather than to the different binding sites. Unidirectional chiral inversion was detected after oral administration of either (-)-(R)-KE-298 or (-)-(R)-M-2 to rats both yielding (+)-(S)-M-2.

Animals↗
PubMed1997

Ncx, a Hox11 related gene, is expressed in a variety of tissues derived from neural crest cells.

We have isolated the murine homeobox gene (Ncx) that belong to a Hox11 gene family. Expression of the Ncx gene was analyzed in total RNAs from embryos by reverse transcribed polymerase chain reaction (RT-PCR). The mRNA was detected in embryos after 9.5 days of embryogenesis (E9.5) and was maximal at E12.5. The RT-PCR also detected the message in total RNAs from adrenal glands and intestine in adult mice. The expression was further examined in various tissues from embryos by in situ hybridization. It was detected in dorsal root ganglia, cranial nerve ganglia (V, IX, X), enteric nerve ganglia and adrenal glands from embryos between E9.5 and E13.5. Since its expression is restricted to tissues derived from neural crest cells, Ncx may play a role in differentiation and proliferation of neural crest lineage cells.

Adrenal Glands↗
PubMed1997

The clinical features of Sjögren's syndrome in Japanese children.

Sjögren's syndrome (SS) is thought to be uncommon in children. An epidemiological study to describe the clinical features distinguishing SS in Japanese children was performed by sending questionnaires to hospitals. A total of 61 cases of SS were reported from 1290 hospitals. The diagnosis of SS was based on histopathological changes and/or sialographic changes in the salivary glands. Forty-two cases had primary SS and 19 were secondary SS with other autoimmune disorders. Fourteen cases (65%) of secondary SS were associated with systemic lupus erythematosus. In primary SS, the initial symptoms were systemic manifestations (fever, exanthema, arthralgia, etc) except for sicca symptoms. In laboratory studies, antinuclear antibodies, elevated serum IgG, rheumatoid factor, anti-Ro/SS-B antibodies were frequently observed.

Child↗
PubMed1997

Comparison of specificity between IgG, IgE and T cells to three casein components: implication for the role of circulating allergen-specific T cells in food allergy.

In order to investigate the role of food antigen-specific T cells circulating in the blood of patients with food allergy, we compared T cell response to three casein components (alpha s-, beta- and, kappa-casein) with specificities of IgG and IgE binding to the casein components in four milk-allergic patients (P1-4) with atopic dermatitis. In all patients the binding activities of IgG antibodies to alpha s-casein were most dominant, followed by those to beta- and to kappa-casein. The major component of casein bound by IgE antibodies was alpha s-casein in P1 and P3, kappa-casein in P2, and alpha s-casein as well as kappa-casein in P4; the order of casein components bound by IgE antibodies was different from that by IgG antibodies. Proliferative responses of peripheral blood mononuclear cells (PBMC) to casein components were so low that the dominance of casein recognition could not be clearly demonstrated. However, short-term T cell lines that specifically respond to casein were successfully established from PBMC of the four patients and the proliferative responses of the T cell lines to the three components of casein were in accord with the IgE antibody specificity to casein components but not with that of IgG antibody specificity. When taken together, these results indicate that casein-specific T cells circulating in the blood are involved in or reflect an allergic reaction against casein.

Caseins↗
PubMed1997

Characterization of monoclonal thyroid-stimulating and thyrotropin binding-inhibiting autoantibodies from a Hashimoto's patient whose children had intrauterine and neonatal thyroid disease.

A multiplicity of TSH receptor autoantibodies (TSHRAbs) have been characterized after subcloning heterohybridomas produced from the lymphocytes of a patient who has Hashimoto's thyroiditis and had three children with intrauterine or neonatal hyperthyroidism. Twelve clones produced stimulating TSHRAbs that increased cAMP levels and iodide uptake in rat FRTL-5 thyroid cells and increased cAMP levels in Chinese hamster ovary (CHO) cells transfected with the human TSHR; like 95% of Graves' stimulating TSHRAbs, all 12 have their functional epitope on the N-terminus of the TSHR extracellular domain, requiring residues 90-165 for activity. All 12 bind to human thyroid membranes in the absence, but not the presence, of TSH, but are only weak inhibitors of TSH binding in assays measuring TSH binding-inhibiting Igs (TBIIs). In contrast, 8 different clones produced TSHRAbs that did not increase cAMP levels, but, instead, exhibited significant TBII activity. Four inhibited the ability of TSH or a stimulating TSHRAb to increase cAMP levels and had their functional epitope on the C-terminal portion of the TSHR external domain, residues 261-370, mimicking the properties of blocking TSHRAbs that cause hypothyroidism in patients with idiopathic myxedema. The 4 other TBIIs inhibited the ability of TSH, but not that of a stimulating TSHRAb, to increase cAMP levels, like TBIIs in Graves' patients. The functional epitope for 3 of these Graves'-like TBIIs was residues 90-165; the functional epitope for the fourth was residues 24-89. The fourth also increased arachidonic acid release and inositol phosphate levels in FRTL-5 thyroid cells and exhibited conversion activity, i.e. the ability to increase cAMP levels in the presence of an anti-human IgG. Thus, this TBII exhibited signal transduction activity, unlike the other 3 Graves'-like TBIIs. The patient, therefore, has stimulating TSHRAbs and 3 different types of TBIIs, each with different functional properties and different epitopes on the TSHR.

Adult↗
PubMed1997

Relationship between the metabolic chiral inversion and chemical structure of 4-phenyl-4-oxobutanoic acids, derivatives of anti-rheumatic agent KE-298.

The relationship between metabolic chiral inversion and chemical structure of various 4-phenyl-4-oxobutanoic acids (4-OBA), derivatives of anti-rheumatic agent KE-298 [2-acetylthiomethyl-4-(4-methylphenyl)-4-oxobutanoic acid], was investigated in rats. Chiral inversion occurred with the thio-alkyl group, whereas the thio-acyl group played no role in the inversion of 4-OBA. A 2-methylene moiety was required for the inversion. When the 4-carbonyl moiety was removed, chiral inversion was significantly decreased, which provided an affinity for the intramitochondrial medium chain fatty acid CoA ligase. In addition, the distance between the chiral center and the carbonyl moiety was also an important factor for chiral inversion. While a sulfur atom was not indispensable for the chiral inversion, the existence of the sulfur atom influenced its affinity to the long chain fatty acid CoA ligase.

Animals↗
PubMed1997

Inhibitory effects of talipexole and pramipexole on MPTP-induced dopamine reduction in the striatum of C57BL/6N mice.

We have investigated the effects of two novel antiparkinsonian drugs, talipexole (Domin) and pramipexole, on MPTP-induced dopamine (DA) reduction in the striatum of C57BL/6N mice in comparison with those of bromocriptine. Fifteen days after MPTP treatment (25 mg/kg, i.p., given daily for 5 days), the DA content in the striatum was decreased to 40-60% of the control value. Among the three dopamine receptor agonists, talipexole and pramipexole (1 mg/kg, i.p., once a day for 20 days) more significantly suppressed the MPTP-induced DA reduction in the striatum than bromocriptine (10 mg/kg, i.p., once a day for 20 days). Talipexole did not influence [3H]MPP+ uptake into striatal synaptosomes. These results suggest that talipexole and pramipexole have a protective effect against MPTP-induced DA reduction in the striatum of C57BL/6N mice.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1997

Effects of talipexole on emesis-related changes in abdominal afferent vagal activity and ileal serotonin metabolism in rats.

The involvement of abdominal afferent vagal activity and serotonergic mechanisms were examined following intravenous administration of talipexole, a dopamine D2 receptor agonist used for treatment of Parkinson's disease, in anesthetized rats. Intravenous administration of dopamine receptor agonists including D1/D2 components increased the spontaneous firing of afferent vagal neurons as did 2-methyl-5-hydroxytryptamine. Both talipexole (0.25-1.0 mg/kg) and bromocriptine (1.0-10.0 mg/kg) increased vagal nerve activity in a dose-dependent manner, and the effect of 10 mg/kg of bromocriptine was significantly greater than that noted with 1.0 mg/kg of talipexole. Increasing vagal firing induced by talipexole was prevented by pretreatment with granisetron, but not with metoclopramide or by spinal section, indicating that afferent vagal firing was mediated via stimulation of the 5-HT3 receptors on the neurons and secondarily caused by stimulation of dopamine receptors. On the other hand, bromocriptine at 5 mg/kg increased 5-HIAA concentration in the ileum, and serotonin turnover (5-HIAA/5-HT) was increased approximately 4-fold when compared to the vehicle group. Bromocriptine also increased the activities of tryptophan hydroxylase and monoamine oxidase. Talipexole at 0.5 mg/kg did not affect ileal 5-HT metabolism and the enzymatic activities. These findings suggest that dopamine receptor agonists may induce changes in abdominal afferent vagal activity and ileal 5-HT metabolism similar to those observed with emetic compounds, and that talipexole has a much smaller influence on serotonin-mediated responses than does bromocriptine with equipotent antiparkinsonian doses. One of the possible reason why talipexole showed fewer emetic side effects in patients with Parkinson's disease may be that the emetic responses triggered by D2 receptor stimulation may secondarily cause an increase of abdominal afferent vagal activity, which may be weakened by the 5-HT3 receptor antagonistic property of talipexole.

Abdomen↗
PubMed1997

[Eosinophils in stool smear in normal and milk-allergic infants].

Stool smears of newborn infants were investigated sequentially from birth through 6 months of life in order to study relation between appearance of eosinophils in stool and feeding of babies. In babies born to non-atopic parents, eosinophils appeared in stool smear soon after start of feeding, but disappeared in a short time. Eosinophils were found irrespective of types of feeding, i.e., breast feeding, powdered milk or amino acid formula. There was tendency of sustained presence of eosinophils in stool smears in babies born to severe atopic parents. These results suggest that appearance in stool of eosinophils does not necessarily mean allergic reaction to ingested foods and need attention in diagnosing milk allergy. Mechanisms of appearance and function of eosinophils in stool in normal babies may differ from those in pathological situations and need further detailed investigation.

Breast Feeding↗
PubMed1997

[Flow cytometric analysis for the activation of peripheral immunoregulatory cells from patients with bronchial asthma].

By use of flow cytometry, we have investigated intracellular activated eosinophil cationic protein (ECP) in eosinophils and mitogen-induced cytokine production of T cells in peripheral blood from children with acute severe asthma. In addition, we measured ECP releasability (serum ECP/lysate ECP) as a maker of activated eosinophils. The monoclonal antibody EG2 (anti-activated ECP/EPX antibody) was used for measuring the amount of intracellular activated ECP. ECP releasability and mean fluorescence intensity (MFI) values of EG2-positive eosinophils increased at the time of asthmatic attack and reduced after treatment with improvement in peak expiratory flow. Furthermore, the frequency of T cells which produced IL-4, IL-5 and IFN-gamma stimulated with phorbol myristate acetate and ionomycin increased and reduced in parallel with MFI of EG2-positive cells. These observations suggest that flow cytometric analysis for intracellular ECP and mitogen-induced cytokine production reflects the activation of T cells in bronchial mucosa, and is useful for monitoring airway inflammation in bronchial asthma.

Adolescent↗
PubMed1996

Prevention of persistent ear drum perforation after long-term ventilation tube treatment for otitis media with effusion in children.

The effect of tape patch technique using Steri-Strip tape in combination with freshening of the perforation edge after removal of long-term ventilation tubes for preventing permanent ear drum perforation was evaluated. The longer the tubes remained in place, the higher the incidence of persistent perforation after tube removal. The perforation rate after Goode T-tube treatment was 4.0% in the spontaneous extrusion group and 14.3% in the intentional removal group. In the ears treated by tape patch application, none of the perforations persisted after removal of the Goode T-tube. After removal or extrusion of Paparella Type II tube, perforations did not close in 13.2% of the group without tape patch application. When a tape patch was applied, only one perforation (3.3%) did not close. From these results, tape patch technique in combinations with freshening of the perforation edge at the time of tube removal was useful to promote healing and prevent persistent ear drum perforation.

Chi-Square Distribution↗
PubMed1996

DMSO induces apoptosis in SV40-transformed human keratinocytes, but not in normal keratinocytes.

We found that dimethyl-sulfoxide (DMSO) at concentrations of 2.5% induced apoptosis in SV40-immortalized human keratinocytes, while normal keratinocytes were arrested at the boundary of G1/S phase under the same conditions. DMSO-induced apoptosis in SV-40 immortalized keratinocytes was not associated with change in phosphorylated state of the retinoblastoma susceptibility gene. When SV40-immortalized cells were treated with 2.5% DMSO, dissociation of the complex was observed by immunoblotting of SV40 T antigen from immunoprecipitated p53 protein fraction.

Antigens, Viral, Tumor↗
PubMed1996

Activation of A3 adenosine receptors on human eosinophils elevates intracellular calcium.

Adenosine (ADO) is a potent bronchoconstrictor in allergic patients and has been shown to increase the release of histamine from human lung tissues. Antagonists of ADO A1 and A2A receptors are not effective in attenuating these effects. Therefore, involvement of ADO A3 receptors in the bronchoconstrictor and/or inflammatory effects have to be considered. Eosinophils also play a pivotal role in allergic diseases such as asthma, thus it is natural to consider a link between the A3 receptor and eosinophils. Human peripheral blood eosinophils express the ADO A3 receptor as indicated by detection of the transcript for A3 receptors in polymerase chain reaction-amplified cDNA derived from the cells. A3 receptors on eosinophil membranes were characterized using the A3 receptor agonist radioligand 125I-labeled AB-MECA, which yielded Bmax and Kd values of 1.31 pmol/mg protein and 3.19 nmol/L, respectively. Treatment of eosinophils with the highly potent and selective A3 receptor agonist CI-IB-MECA clearly induced Ca2+ release from intracellular Ca2+ pools followed by Ca2+ influx, suggesting the presence of phospholipase C-coupled A3 receptors. In contrast, the ADO receptor agonists CPA and CGS 21680, selective for A1 and A2A receptors, respectively, at concentrations of < or = 30 mumol/ L did not elevate the intracellular Ca2+ level. These results attest to the existence of ADO A3 receptors on eosinophils and suggest that ADO stimulates these cells to release Ca2+ from intracellular stores via the activation of A3 receptors.

Adenosine↗
PubMed1996

Induction of Graves-like disease in mice by immunization with fibroblasts transfected with the thyrotropin receptor and a class II molecule.

Graves disease is an autoimmune thyroid disease characterized by the presence of antibodies against the thyrotropin receptor (TSHR), which stimulate the thyroid to cause hyperthyroidism and/or goiter. By immunizing mice with fibroblasts transfected with both the human TSHR and a major histocompatibility complex class II molecule, but not by either alone, we have induced immune hyperthyroidism that has the major humoral and histological features of Graves disease: stimulating TSHR antibodies, thyrotropin binding inhibiting immunoglobulins, which are different from the stimulating TSHR antibodies, increased thyroid hormone levels, thyroid enlargement, thyrocyte hypercellularity, and thyrocyte intrusion into the follicular lumen. The results suggest that the aberrant expression of major histocompatibility complex class II molecules on cells that express a native form of the TSHR can result in the induction of functional anti-TSHR antibodies that stimulate the thyroid. They additionally suggest that the acquisition of antigen-presenting ability on a target cell containing the TSHR can activate T and B cells normally present in an animal and induce a disease with the major features of autoimmune Graves.

Animals↗