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Biomedical subjects

S Ishida

Publications and source records attributed to S Ishida.

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

Isolation and analysis of cellular DNA fragments directly binding to c-Myc protein.

c-Myc protein, the product of cellular oncogene c-myc, is thought to play an important role in the control of cell cycle progression by binding to the E-box sequence (CACGTG) of cellular DNA, but only a few target genes are known. We cloned two small human DNA fragments (n16 and r37) that bound to c-Myc protein in vitro by random screening. Both clones contained the E-box sequence, to which c-Myc protein bound directly in vitro. Northern blot analysis showed that a low molecular-weight RNA was transcribed from the region near the n16 c-Myc binding site. The function of this low molecular-weight RNA and the regulatory role of c-Myc protein in related transcription are now under investigation.

Base Sequence↗
PubMed1996

Fusion of an ETS-family gene, EIAF, to EWS by t(17;22)(q12;q12) chromosome translocation in an undifferentiated sarcoma of infancy.

EIAF is a newly isolated ETS-family gene that is located on 17q21 and codes for the adenovirus EIA enhancer-binding protein. In our chromosome analysis of 18 of the Ewing family of tumors and undifferentiated sarcomas, we found t(17;22)(q12;q12) in an MIC2 antigen-positive undifferentiated sarcoma of infancy. On Southern blot analysis, EWS and EIAF cDNA probes hybridized to the same rearranged band, indicating that an EWS-EIAF fusion gene was formed in the tumor. Further Southern blot analysis using four EIAF cDNA probes of different sizes showed that the breakpoint lies in the region upstream to the ETS domain of the EIAF gene. EIAF may be the fourth ETS-family gene to be identified forming a fusion gene with EWS. We assume that the RNA binding domain of EWS may have been replaced by the DNA binding domain of EIAF in the EWS-EIAF fusion protein as in other fusion proteins previously characterized in Ewing sarcoma and other types of sarcomas.

Adenovirus E1A Proteins↗
PubMed1996

The mode of expression and promoter analysis of the arcA gene, an auxin-regulated gene in tobacco BY-2 cells.

The arcA, a member of the G protein beta-subunit family, was isolated from tobacco BY-2 cells as an auxin-responsive gene. Characterization of arcA, which should help to elucidate the function of the gene product in the plant cells, was performed with emphasis on the mode of expression and the analysis of its promoter. Accumulation of the arcA message was detected only after treatments with auxins and not after treatments with other phytohormones or CdCl2, implying that responsiveness of arcA was exclusive to auxin. The putative arcA promoter region was fused to a reporter gene for beta-glucuronidase (GUS), and transient expression was analyzed in tobacco BY-2 cells. Two series of arcA promoter/GUS chimeric genes were constructed. One consisted of a set of 5' nested deletions of the arcA promoter connected to the gene for GUS and the other consisted of a variety of the arcA promoter fragments fused to a minimal promoter-GUS construct. The results indicated that the promoter sequence covering four sets of direct repeats (-562 to -167) was necessary for the sufficient response of arcA promoter to auxin in BY-2 cells. Moreover, irrespective of auxin treatment, elevated activity of GUS driven by this promoter fragment was detected, a result that implies that this region behaves an enhancer in BY-2 cells.

Base Sequence↗
PubMed1996

Interictal cerebral and cerebellar blood flow in temporal lobe epilepsy as measured by a noninvasive technique using Tc-99m HMPAO.

The usefulness of noninvasive regional cerebral blood flow measurements using Tc-99m hexamethylpropylene amine oxime (HMPAO) was evaluated in 45 patients with interictal temporal lobe epilepsy. Seizure frequency did not show any influence on flow values or side-to-side asymmetry. Patients taking phenytoin had a significantly lower mean cerebral blood flow (mean 9.5%) and lower mean cerebellar blood flow (mean 12.9%) than those not taking it. Moreover, phenytoin reduced regional cerebral blood flow in the temporal regions more prominently on the contralateral side of the epileptic focus than on the ipsilateral side. Positive MRI findings of hippocampal sclerosis along with visually detected temporal hypoperfusion on SPECT showed a lower regional cerebral blood flow and greater flow asymmetry than other imaging findings in the temporal region. Results suggest that noninvasive cerebral blood flow measurements using Tc-99m HMPAO may give useful information about interictal cerebral blood flow around an epileptic focus and about the effects of antiepileptic drugs on brain function in temporal lobe epilepsy.

Adolescent↗
PubMed1996

Investigation of IFN type-I receptor and IFN regulatory factor expression relating to induction of 2', 5'-oligoadenylate synthetase in cells persistently infected with the mumps virus.

Poor induction of interferon-induced 2', 5'-oligoadenylate synthetase (2-5AS) activity has been demonstrated in cells persistently infected with the mumps virus or human T-lymphotropic virus type-I (HTLV-I). The suppression of 2-5AS induction is the result of the repression of 2-5AS gene expression at the transcription level. In a general way, after the binding of interferon-alpha (IFN-alpha) to cell surface-specific receptors, expression of 2-5AS gene is thought to be regulated by some transacting factors, IFN-regulatory factors (IRF-1 and IRF-2) and the IFN-stimulated gene factor (ISGF-3, a complex consisting of STAT-1 alpha, STAT-2 and p48). To clarify the cause of the suppression mechanism(s), fluctuation in the number of IFN receptors and the levels of mRNAs in both IRF-1 and IRF-2 were examined in cells persistently infected with the mumps virus (FLMT and KBMT). There were few differences in the number of IFN receptors and the level of IRF-2 mRNA between persistently infected cells and uninfected control cells. After the treatment of cells with IFN, a slight reduction of IRF-1 mRNA was found in persistently infected cells as compared with that of the uninfected control cells.

2',5'-Oligoadenylate Synthetase↗
PubMed1996

Quantification of systemic and local immune responses to individual rotavirus proteins during rotavirus infection in mice.

The purpose of the present study was to develop a quantitative assay that could be used to measure the local and systemic immune responses to specific rotavirus proteins following rotavirus infection of adult mice. To measure these responses, we used an immunocytochemical staining assay of Spodoptera frugiperda (Sf-9) cells which were infected with recombinant baculovirus expressing selected rotavirus proteins. The specificity of the assay was documented by using a series of monoclonal antibodies to individual rotavirus proteins. We observed that the assay had high levels of sensitivity and specificity for a series of VP7- and VP4-specific neutralizing monoclonal antibodies which recognized conformation-dependent epitopes on their target proteins. We also studied immunoglobulin G (IgG) immune responses in serum and IgA immune responses in the stools of mice infected with wild-type murine rotavirus strain EHPw. In both sera and stools, the most immunogenic proteins were VP6 and VP4. VP2 was less immunogenic than VP6 or VP4, and the immune responses to VP7, NSP2, and NSP4 were very low in serum and undetectable in stools.

Animals↗
PubMed1996

Caffeine induces ventricular tachyarrhythmias possibly due to triggered activity in rabbits in vivo.

Caffeine induces delayed afterdepolarizations (DADs) and triggered activity in isolated cardiac tissue. We investigated the ability of caffeine to induce triggered ventricular arrhythmias in rabbits in vivo. During continuous infusion of caffeine at doses of 0.3 or 1.0 mg/kg per min, ventricular pacing was performed with 50 stimuli with a cycle length of 220 msec (basic pacing train) every 5 min until ventricular tachycardia (VT) was induced. The effects of programmed stimulation and pharmacologic agents on the induction of ventricular ectopic beats (VEBs) were examined. Pacing protocols were carried out in the presence of vagal-induced slowing of sinus rhythm. VT was induced by a basic pacing train during the infusion of caffeine at 1.0 mg/kg per min, but not at 0.3 mg/kg per min. An increase in the pacing rate or the number of stimuli resulted in 1) a decrease in the first postpacing interval, and 2) an increase in the number of postpacing VEBs. Induction of VT was suppressed by intravenous bolus injections of verapamil, propranolol and adenosine. At the time of the initial induction of VT, the plasma concentration of caffeine was 87 +/- 2 micrograms/ml and the plasma level of norepinephrine increased from 666 +/- 166 pg/ml at baseline to 1121 +/- 245 pg/ml. These results suggest that catecholamine-associated triggered activity may be responsible for caffeine-induced VT.

Animals↗
PubMed1996

Comparison of pH and ionic strength dependence of interactions between monoclonal antibodies and bovine beta-lactoglobulin.

A panel of 13 monoclonal antibodies (mAbs) against distinct determinants on bovine beta-lactoglobulin, a model protein antigen, were examined and compared for their ability to bind and desorb from the antigen at differing pHs and ionic strengths by an enzyme-linked immunosorbent assay and elution assay. Among them, mAb 61C1 was found to be highly sensitive to the pH, and 3 in 4 mAbs directed to the region 42-56 also strongly depended on the change in ionic strength. Because of the large proportion of charged amino acid residues in the region 42-56, the electrostatic forces are considered to be more predominant than the hydrophobic interactions in the latter antigen-antibody reactions, thereby resulting in their high sensitivity to the ionic strength.

Amino Acid Sequence↗
PubMed1996

[A 4-week intravenous toxicity study of the active metabolite (NM394) of prulifloxacin (NM441) in rats followed by a 4-week recovery test].

A repeated dose toxicity study of ( +/- )-6- fluoro-1-methyl-4-oxo-7-(1-piperazinyl)-4H- [1,3]thiazeto[3,2-a]quinoline-3-carboxylic acid (NM394), the active metabolite of a new antibacterial agent, prulifloxacin, was conducted in Sprague-Dawley rats. Male and female rats were given the test material intravenously for 4 weeks at doses of 0 (control), 3, 10 and 30 mg/kg. After discontinuation of the treatment, a 4-week recovery test was also conducted. There were no treatment-related effects on survival, clinical signs, body weight and food consumption. Ophthalmoscopic and hematologic examinations failed to show any abnormalities related to the treatment. Increased water consumption was observed in the 10 and 30 mg/kg groups. In these dose groups, increased urine volume and lowered urine specific gravity, and crystalline substance and small epithelial cells in urinary sediments were seen. Cloudy urine was also seen in the 30 mg/kg group. Blood chemical examination showed decreased gamma-globulin in the 10 and 30 mg/kg groups and increased BUN and creatinine in the 30 mg/kg group. Pathological changes caused by the treatment were as follows. In kidney, tubular nephrosis with crystalline substance was observed in the 10 and 30 mg/kg groups and its organ weight was increased in the 30 mg/kg group. Cecal weight was increased in the 30 mg/kg group. The above-mentioned changes were reversible except for decreased gamma-globulin. Plasma levels and urinary concentrations of the test material were increased in all dose groups with dose-related manner, whereby no sex differences were observed. No effects caused by the repeated dosing were seen in the plasma concentrations. Toxicological findings were not observed in the 3 mg/kg group. The results show that the NOAEL of NM394 is 3 mg/kg for 4-week repeated dose toxicity in rats.

Animals↗
PubMed1996

Cytotoxicity of NaCl, a stomach tumor promoter, and prevention by rice extract in stomach mucosa of F344 rats.

Cytotoxicity of NaCl and its prevention by rice extract were studied in the pyloric mucosa of male F344 rat stomach after oral administration of rice extract and 2.6 M NaCl. Effect were observed histologically by hematoxylin and eosin staining and the bromodeoxyuridine method. Replicative DNA synthesis (RDS) was assayed by liquid scintillation counter with [3H]thymidine. NaCl (2.6 M) induced destruction of the surface mucous cells within 1 min. RDS and S-phase cells increased significantly (p < 0.01) and to a maximum at 17 h, and returned to control levels 48 h after exposure. Administration of aqueous rice extract 3 h before NaCl exposure reduced the morphological damage to the mucosa and prevented the increase in RDS dose dependently by up to 65% (p < 0.01). These results showed that NaCl induced rapid mucosal damage and cell proliferation in rat stomach mucosa and that rice extract prevented the damage and reduced the increase in RDS.

Animals↗
PubMed1996

Carboxyl-terminal mutations of Gq alpha and Gs alpha that alter the fidelity of receptor activation.

The carboxyl terminus of the G protein alpha subunit is a key determinant of the fidelity of receptor activation. We have previously shown that the Gq alpha subunit (alpha q) can be made to respond to alpha i-coupled receptors by replacing its carboxyl terminus with the corresponding alpha i2, alpha o, alpha z residues. We now extend these findings in three ways: 1) carboxyl-terminal mutations of alpha q/alpha i chimeras show that the critical amino acids are in the -3 and -4 positions, 2) exchange of carboxyl termini between alpha q and alpha z allows activation by receptors appropriate to the carboxyl-terminal residues, and 3) we identify receptors that either do or do not activate the expected carboxyl-terminal chimeras (alpha q/alpha i, alpha q/alpha s, alpha s/alpha q). Replacement of the five carboxyl-terminal amino acids of alpha q with the alpha s sequence permitted an alpha s-coupled receptor (the V2 vasopressin receptor but not the beta 2-adrenergic receptor) to stimulate phospholipase C. Replacement of the five carboxyl-terminal amino acids of alpha z with residues of alpha q permitted certain alpha q-coupled receptors (bombesin and V1a vasopressin receptors but not the oxytocin receptor) to stimulate adenylyl cyclase. Thus, the relative importance of the G alpha carboxyl terminus in permitting coupling to a new receptor depends on the receptor with which it is paired. These studies refine our understanding and provide new tools with which to study the fidelity of receptor/G alpha activation.

Animals↗
PubMed1996

[Changes in clinical and immunological status after post-thymectomized irradiation for invasive thymoma with myasthenia gravis].

We report a detailed analysis of the clinical courses and the immunological examinations in seven patients with myasthenia gravis (MG) and invasive thymoma (Ossermann's type I: 3 cases, IIa: 1 case and IIb: 3 cases), who underwent a transsternal extended thymectomy and postoperative radiation therapy. Two patients with Ossermann's type IIb showed the deterioration of MG after the irradiation. Immunological examinations by an analysis of the subsets of peripheral blood lymphocytes demonstrated a significant decrease of the proportion in CD4 + CD45RA+ T (naive) cells and a significant increase in CD4 + CD45RA-(memory) T cells. Further, the percentage of activated (HLADR+) CD4T cell subsets were increased. The present study suggests that post-thymectomized irradiation may change the balance of the proportion in CD4+ T cell subsets, thereby resulting in the deterioration of MG.

Adult↗
PubMed1995

CD40 signaling-mediated induction of Bcl-XL, Cdk4, and Cdk6. Implication of their cooperation in selective B cell growth.

Signals sent through CD40 play crucial roles in B cell differentiation, including blocking apoptosis of germinal center B cells. In this study, using a murine B cell WEHI-231 line that undergoes apoptosis by the cross-linking of surface Ag receptors (sIgM), we have demonstrated that CD40 signalings are linked to induction of the Bcl-xL, Cdk4, and Cdk6 proteins whose expression was significantly suppressed by the apoptotic signal through sIgM. Mutational analyses of CD40 revealed that the domain of human CD40 required for blocking apoptosis of WEHI-231 cells coincides with that required for Bcl-xL induction. Signals through sIgM arrest cells in the G1 phase of the cell cycle, which is followed by apoptosis. However, while constitutive expression of Bcl-XL leads to the inhibition of apoptosis. Nevertheless, Bcl-xL fails to induce S phase entry. By CD40 signalings, both Cdk4 and Cdk6 resume their normal expression levels, which are sufficient for passing the restriction point in G1 even in the presence of the apoptotic signals mediated by sIgM. These results suggest that cooperation of Bcl-xL, Cdk4, and Cdk6 induced by CD40 signaling plays a key role in CD40-mediated selective growth of B cells.

Amino Acid Sequence↗
PubMed1995

Aberrant cGMP-binding activity in non-chemotactic Dictyostelium discoideum mutants.

The kinetics of cGMP-binding to the major cGMP-binding activity in Dictyostelium were investigated in 10 non-chemotactic mutants (KI mutants; KI-1 approximately 10). A wild-type cell contains about 3000 binding sites with a Kd of 1.5 nM. cGMP may dissociate from these binding sites with fast (F-type) or slow (S-type) kinetics, and DNA has been shown to promote the conversion of F- to S-type of cGMP-binding. The 10 mutants were placed in 4 classes, based on equilibrium and non-equilibrium binding properties and the effect of DNA. Class I mutants (KI-1, 3 and 8) have normal cGMP-binding properties. Class II mutants (KI-2, 6 and 7) show increased Kd values but nearly normal Bmax, normal F/S ratio and normal effects of DNA. Class III mutants (KI-4, 5 and 10) have a strongly decreased Kd and increased Bmax, nearly all binding sites are of the S-type and DNA does not affect the binding; apparently these mutants have a cGMP-binding protein locked in the S-form. cGMP-binding in class IV mutant (KI-9) is normal except that the number of binding sites is increased about 3-fold. The finding of seven mutants with altered cGMP-binding in 10 non-chemotactic mutants suggests that the cGMP-binding activity plays an important role in the chemotactic signal transduction pathway.

Animals↗
PubMed1995

Identification of auxin-responsive elements of parB and their expression in apices of shoot and root.

Detailed analysis of transgenic tobaccos containing a series of chimeric parB promoter/beta-glucuronidase (GUS) gene constructs allowed us to define two auxin-responsive elements (AREs) of 48 bp and 95 bp (positions -210 to -163 and -374 to -280) in the parB promoter. The two AREs responded independently to physiological concentrations of auxin. Gel retardation assays revealed binding of nuclear protein(s) to the sequence conserved between ARE I and ARE II. The auxin responsiveness of the parB promoter did not mediate the pathway through the as-1 element and transcription factor ASF-1. AREs I and II were responsive to auxin at physiological concentrations, whereas as-1 responded only to higher concentrations of auxin which may be interpreted as stress, though as-1 had been reported to be a minimal ARE [Liu, X. & Lam, E. (1994) J. Biol. Chem. 269, 668-675]. Histochemical staining of transgenic tobacco that contained a parB promoter/GUS construct demonstrated the expression of GUS activity in the shoot apex as well as in the root tips, suggesting the involvement of parB expression in meristematic activity or differentiation. The drastic change in auxin responsiveness in the transgenic plants between the 6th and 10th day after imbibition of seeds implies the development or the activation of auxin signal transduction systems during plant development.

Bacterial Proteins↗