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Biomedical subjects

S Iwata

Publications and source records attributed to S Iwata.

At least 73 records · Page 4Linked to original sources
PubMed1999

Demonstration of the interaction of thioredoxin with p40phox, a phagocyte oxidase component, using a yeast two-hybrid system.

Thioredoxin (TRX) has disulfide reducing activity and is reported to be involved in various cellular functions including the promotion of cell growth and apoptosis. To help understand the molecular mechanism through which TRX is involved in immunological systems, we screened a cDNA library derived from a B-cell population of Epstein-Barr virus-transformed human peripheral blood lymhocyte for TRX binding proteins by use of a yeast two-hybrid system. Among plasmids from positive clones, a plasmid contained an insert which has homology with human p40phox, a cytosolic component of phagocyte oxidase. This insert sequence extended from the base + 181 to the stop codon of p40phox. The entire coding region of p40phox was shown to interact with TRX both in assays of histidine prototrophy and beta-galactosidase activity; in contrast, no interaction was observed with substituted mutant TRX (C32S/C35S), which lacks reducing activity. These results showed that p40phox interacts with TRX and indicated the possibility of TRX-dependent regulation of phagocyte oxidase activity.

Amino Acid Sequence↗
PubMed1999

Anti-tumor activity of antizyme which targets the ornithine decarboxylase (ODC) required for cell growth and transformation.

Anti-tumor activity of antizyme which targets the ornithine decarboxylase (ODC) required for cell growth and transformation Cell proliferation and transformation induced by growth factor stimulation or by carcinogens, viruses, or oncogenes are characterized by an associated increase in polyamine levels, which is mediated by increased polyamine biosynthesis and enhanced uptake of polyamines. Polyamine biosynthesis is catalyzed particularly, in the level of ornithine decarboxylase (ODC). The elevation of cellular polyamine levels on the other hand accelerates the induction of ornithine decarboxylase antizyme (antizyme), which is involved not only in ODC-degradation, but in the negative regulation of polyamine transport. Taking advantage of these characteristics of antizyme, the potential of antizyme as a factor having anti-cell growth and anti-tumor activity was investigated. We show that antizyme can induce cell death associated with a rapid decline of intracellular polyamine contents. The possible anti-tumor activities of ectopically expressed antizyme were tested in p21H-ras (Val 12)-transformed NIH3T3 cells and several human malignant cell lines including a line with loss of p53 expression, and they were shown to be as sensitive as nontransformed NIH3T3 cells in vitro. The in vivo anti-tumor activity was also tested using nude mice inoculated with H-ras transformed NIH3T3 cells that had been transfected with inducible antizyme expression vector and the results showed that antizyme expression in vivo blocks tumor formation in these mice. These results suggest that ectopic antizyme expression is of possible therapeutic benefit in the treatment of cancer, which is mediated by ODC inactivation and intracellular polyamine depletion.

3T3 Cells↗
PubMed1999

Effect of selegiline on dopamine concentration in the striatum of a primate.

Monoamine oxidase (MAO) has two subtypes, A and B, that have different distributions between the rodent and the human. In the striatum, dopamine (DA) of the rat seems to be metabolized by MAO A, and DA of the human is largely deaminated by MAO B. MAO in the striatum of common marmosets is also type B. Using in vivo microdialysis, we investigated the pharmacological activity of selegiline, a selective irreversible inhibitor of MAO B, in the striatum of marmosets. Intraperitoneal co-administration of selegiline (1 mg kg-1, i.p.) with levodopa/carbidopa (10/2.5 mg kg-1, i.p.) did not significantly increase extracellular concentration of DA in the striatum of common marmosets compared with control animals receiving levodopa/carbidopa alone. Daily pretreatment with 0.1 mg kg-1 (i.p.) selegiline for two weeks, however, dramatically increased extracellular concentration of DA to about seven times that of control animals treated with levodopa/carbidopa alone in marmosets. Such an increase in extracellular concentrations of DA could not be observed in a similar study with Wistar rats. This study showed that chronic administration of a small dose of selegiline caused a marked increase in extracellular DA concentration in the striatum of primates, but not in the rodents.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1999

Myocardial high-energy phosphates and hepatic redox state in jaundiced rats.

BACKGROUND: The mechanism underlying the fatal complications in jaundiced states after shock has not been fully clarified. The present study was designed to examine the effect of hemorrhagic shock on myocardial high-energy phosphate stores and the arterial ketone body ratio (AKBR:acetoacetate/beta-hydroxybutyrate), which reflects the redox state of the liver mitochondria, in normal and jaundiced rats. MATERIALS AND METHODS: At 1 week after ligation of the common bile duct, hemorrhagic shock was induced by exsanguination (mean arterial blood pressure = 40 mmHg) and maintained for 2 h. Serial changes in AKBR were measured. The myocardial adenine nucleotides phosphocreatine (PCr) and inorganic phosphate (Pi) were determined before and after hemorrhagic shock. RESULTS: Before shock, myocardial ATP in the jaundiced group was lower than that in the sham group. However, the myocardial PCr levels in the two groups did not differ. After reinfusion of the shed blood, ATP and PCr recovered to the preshock levels in the sham group. However, ATP and PCr were further increased in the jaundiced group. At 60 min after reinfusion, AKBR recovered to the normal level in the sham group, but decreased below 0.7 in the jaundiced group. Metabolic acidosis was more severe in the jaundiced group than in the sham group. CONCLUSIONS: The decrease in AKBR indicated irreversible metabolic acidosis. As a result, fatal circulatory failure occurred, although the phosphoenergetic level in the myocardium was sufficiently maintained.

Acidosis↗
PubMed1999

Conformational change of the Rieske [2Fe-2S] protein in cytochrome bc1 complex.

Structures of mitochondrial bc1 complex have been reported based on four different crystal forms by three different groups. In these structures, the extrinsic domain of the Rieske [2Fe-2S] protein, surprisingly, appeared at three different positions: the "c1" position, where the [2Fe-2S] cluster exists in close proximity to the heme c1; the "b" position, where the [2Fe-2S] cluster exist in close proximity to the cytochrome b; and the "intermediate" position where the [2Fe-2S] cluster exists in-between "c1" and "b" positions. The conformational changes between these three positions can be explained by a combination of two rotations; (1) a rotation of the entire extrinsic domain and (2) a relative rotation between the cluster-binding fold and the base fold within the extrinsic domain. The hydroquinone oxidation and the electron bifurcation mechanism at the Q(P) binding pocket of the bc1 complex is well explained using these conformational changes of the Rieske [2Fe-2S] protein.

Animals↗
PubMed1999

Assessment of the dominant abnormal form is useful for predicting the outcome of intracytoplasmic sperm injection in the case of severe teratozoospermia.

PURPOSE: Our purpose was to investigate the relation between the dominant sperm anomaly and sperm morphology and the outcome of intracytoplasmic sperm injection (ICSI). METHODS: Two hundred ninety-five patients who underwent a total of 181 cycles of in vitro fertilization (n = 168) and/or 217 cycles of ICSI (n = 177) between July 1995 and May 1997 at Keio University Hospital were investigated. RESULTS: The rates of fertilization and pregnancy were 63.3 and 27.8%, respectively, in ICSI cycles with < or = 4% normal forms. When the percentage of strictly normal morphology was < or = 4, the fertilization rate was lower in the case of severely tapered head (13.0%; n = 4) than in the cases of other deformities in ICSI. The acrosomal defect made no difference in the fertilization rate with ICSI. CONCLUSIONS: The predominant abnormal form affects the ICSI outcome in the case of < or = 4% normal forms.

Adult↗
PubMed1999

DNA damage-associated cell cycle and cell death control is differentially modulated by caffeine in clones with p53 mutations.

Caffeine is known to potentiate the cytotoxic effects of DNA damaging agents and increases the sensitivity of p53-deficient cells to X-irradiation (X-IR). We have analyzed the cell cycle and cell death control after X-IR in the absence or presence of caffeine in hematological cell lines with various configurations of the p53 gene; EBV-immortalized lymphoblastoid cells with heterozygous p53 mutation (wt/mt), human leukemia cell lines HL60 and KOPM28 with no and mutant p53 expression, respectively. These cell lines display an impaired G0/G1 checkpoint and G2 delay following X-IR, and resistance to apoptosis, which are in accordance with findings previously reported. When irradiated in combination with caffeine, all these cell lines overrode the G2 delay and accumulated at G0/G1. The cell cycle modifications in these cell lines correlated with the increase in radiation-induced p34Cdc2 kinase activity by caffeine. These cell cycle control modifications by caffeine, however, were not associated with enhancement of radiation-induced apoptosis or reduction of clonogenic growth activity in these cell lines. These results suggest that the cytocidal effect of caffeine may need to be verified independently of its cell cycle regulatory activities at least in some cases with p53 mutation.

Amino Acid Substitution↗
PubMed1999

Specific inhibition of TH2-type cytokine production from human peripheral T cells by terfenadine in vitro.

BACKGROUND: Cytokine imbalance is thought to be one of the causes for allergic diseases. The effect of anti-allergic drugs on cytokine production from T cells should be examined in a convenient way. OBJECTIVES: To study the in vitro effect of terfenadine, a prototype non-sedating H1 receptor antagonist, on cytokine production from activated T cells. METHODS: T cells were cultured in the presence of terfenadine on anti-CD3 mAb and anti-CD26 mAb-coated wells, anti-CD3 mAb and anti-CD28 mAb-coated wells, and anti-CD3 mAb wells with PMA. T-cell proliferation, along with the concentrations of interleukin (IL) -2, interferon (IFN) -gamma, IL-4, and IL-5 were measured. RESULTS: Terfenadine inhibited T-cell proliferation and IL-4 and IL-5 production under each costimulatory condition tested, whereas it had no effect on IL-2 and IFN-gamma production. CONCLUSIONS: These results indicate that terfenadine has a specific inhibitory effect on TH2-type cytokine production induced by several ways of costimulatory activation.

Cells, Cultured↗
PubMed1999

CD26/dipeptidyl peptidase IV differentially regulates the chemotaxis of T cells and monocytes toward RANTES: possible mechanism for the switch from innate to acquired immune response.

CD26, a 110 kDa cell surface glycoprotein, exhibits dipeptidyl peptidase IV (DPPIV; EC 3.4.14.5) enzyme activity and plays an important role in T cell co-stimulation. In the present study, the function of CD26/DPPIV in transendothelial migration was examined using beta-chemokines as chemoattractants. When soluble recombinant CD26 (sCD26/DPPIV+) was added to the transendothelial chemotaxis system, chemotactic migration of T cells toward RANTES was significantly enhanced. Addition of sCD26 to 50 ng/ml of RANTES enhanced the migratory response by a factor of two compared to RANTES alone, whereas mutant soluble CD26 (mCD26), lacking the DPPIV enzyme activity, had no enhancing effect on RANTES-induced T cell migration. In the process of analyzing the mechanisms of the enhancement of T cell migration by sCD26, we showed that RANTES was cleaved by sCD26 under physiologic conditions at the precise site characteristic of its enzyme specificity. However, synthesized RANTES which lacks two N-terminal amino acids showed a chemotactic activity equivalent to full-length RANTES on T cells. Furthermore, addition of sCD26 showed enhancement of T cell migration induced by both forms of RANTES. In contrast to T cells, the truncated RANTES is inactive in chemotaxis of purified monocytes and supplement of sCD26 but not mCD26 reduced the migratory response of monocytes to RANTES. These results suggest that CD26/DPPIV differentially regulate the chemotactic response of T cells and monocytes to RANTES.

Amino Acid Sequence↗
PubMed1999

Endothelial nitric oxide synthase expression in tumor vasculature is correlated with malignancy in human supratentorial astrocytic tumors.

OBJECTIVE: Endothelial nitric oxide synthase (eNOS) may play an important role in the regulation of tumor blood flow and vascular permeability. However, there have been no reports describing alterations of eNOS expression in relation to malignant progression in human astrocytic tumors. We immunohistochemically studied the relationship between eNOS expression in tumor vasculature and malignancy in supratentorial astrocytic tumors. METHODS: Tissue samples were obtained from 12 patients with low-grade astrocytomas, 10 with anaplastic astrocytomas, and 17 with glioblastomas. Normal brain tissue samples were obtained from four patients with other brain diseases. Immunohistochemical staining was performed using the avidin-biotin complex method, with polyclonal anti-eNOS antibody, and the levels of eNOS expression in endothelial cells were evaluated as slight, moderate, or intense on the basis of eNOS immunoreactivity. The proliferative potential was assessed as the MIB-1 staining index for tumor cells. RESULTS: The expression of eNOS was slight in all specimens of normal brain tissue, slight in 7 and moderate in 5 specimens of low-grade astrocytoma, slight in 2, moderate in 6, and intense in 2 specimens of anaplastic astrocytoma, and moderate in 5 and intense in 12 specimens of glioblastoma. The MIB-1 staining index (mean+/-standard deviation) was 0.2+/-0.2% for normal specimens, 1.8+/-0.6% for low-grade astrocytomas, 9.6+/-6.9% for anaplastic astrocytomas, and 18.5+/-7.7% for glioblastomas. The MIB-1 staining indices for slight, moderate, and intense eNOS expression were 2.0+/-2.3%, 10.8+/-9.8%, and 16.9+/-7.7%, respectively. CONCLUSION: Expression of eNOS in tumor vessels was significantly correlated with histological grade and proliferative potential. These findings suggest that astrocytic tumor vessels possess higher activity for nitric oxide production than do normal vessels.

Adolescent↗
PubMed1999

[Effect of antibiotics and antibody on phagocytic bactericidal activity of polymorphonuclear neutrophils of Bordetella pertussis].

The phagocytic bactericidal activity of the polymononucler neutrophils (PMNs) that were collected from healthy volunteer with and without antibody against Bordetella pertussis was investigated. Furthermore, these activity against B. pertussis under observing penicillins or macrolides antibiotics was investigated. Although no efficacy to B. pertussis strain by the PMNs in serum without antibody, but the viable cells of B. pertussis decreased to 1/1,000 1 hr after incubation and was not detected after 4 hrs. In particular, the viable cells of B. pertussis by the PMNs in serum with antibody was markedly reduced when azithromycin was present. These results suggests that the synergistic action of macrolide antibiotics and antibody-mediated phagocytic bactericidal activity on B. pertussis may have clinical relevance.

Anti-Bacterial Agents↗
PubMed1999

[Detection of anti-Chlamydia trachomatis antibody by means of enzyme immunoassay using synthetic peptide antigen].

Newly developed diagnostic kits for the detection of Anti-Chlamydia trachomatis, Peptide-Chlamvdia (LOY: Meiji Milk Products Co., Ltd., Tokyo; for IgG and IgA), were evaluated using the microimmunofluorescence assay (MIF) as the gold standard. These results were also compared to results of testing by Sero-IPALISA and immunoblot (I-B). Detection by LOY in based on enzyme immunoassay with synthetic peptides as the antigen. Thirty serum samples from pediatric patients and 130 serum samples from gynecology patients were used. All 26 pediatric samples that were positive for Chlamydia pneumoniae IgG antibody tested negative with LOY, indicating that the presence of the antibody against C. pneumoniae did not affect the assay by LOY. For 90 gynecological samples, the total, the positive and the negative agreement rates for IgG were quite high; i.e. 87.8%, 90.0% and 70.0% (LOY vs MIF), 85.6%, 85.0% and 90.0% (Sero-IPALISA vs MIF), and 92.0%, 94.9% and 70.0% (I-B vs MIF), respectively. On the other hand, many cases of MIF (-) and LOY (+) discrepancy were seen in IgA detection. In order to better understand the basis for such disagreement. 34 serum samples were collected from patients whose cervical samples were negative for the Chlamydia group antigen based on the assay with IDEIA-Chlamydia. They were then assayed by MIF and LOY. The total, the positive and the negative agreement rates for IgG were 91.2%, 100% and 90.9%, while the total and the negative agreement rates for IgA were 88.2% and 88.2% (there were no IgA positive cases). Furthermore, 6 serum samples (1 case of MIF (+) LOY (+) and 5 cases of MIF (-) LOY (+)) were provided to determine whether LOY detects C. trachomatis specific IgA antibody. Increasing amounts of C. trachomatis serovar L2 were added to the serum samples resulting in a progressive decrease in their reactivity in the LOY assay. These results lead us to speculate that LOY can reveal even low levels of C. trachomatis specific IgA antibody. In conclusion, LOY can be used as an useful kit for detecting C. trachomatis antibody.

Antibodies, Bacterial↗
PubMed1999

[Influence of dexamethasone on the clinical course of bacterial meningitis in children. Especially on secondary fever. Experiences in 27 institutions].

Of pediatric patients with purulent meningitis seen at the institutions listed in the title page of this paper between 1986 and 1994, 93 patients treated with antibiotics and dexamethasone (DXM) were compared with 91 patients treated with antibiotics alone. The patients receiving antibiotics with dexamethasone achieved overall improvement in inflammatory symptoms and signs and cerebrospinal fluid findings and became afebrile significantly earlier than those receiving antibiotics alone. However, some of the patients became febrile again. The secondary fever rate for the DXM group was much higher than that for the antibiotic alone group (p < 0.0001). In most of the rebounded cases, the body temperature rose above 38 degrees C and remained elevated for 2-4 days. Cerebrospinal fluid (CSF) was cultured daily in 54 and 32 patients receiving antibiotics with and without DXM, respectively. Although this study was not a controlled study in a strict sense, these patients compared. In both groups, the CSF became mostly culture-negative within 48 hours. In a few patients receiving DXM, however, it became culture-negative after 72 hours or longer. DXM caused an adverse effect in a patient with meningitis caused by Streptococcus pneumoniae. The adverse effect was mild gastrointestinal bleeding, which recovered spontaneously. From the findings described above, the use of DXM combined with antibiotic therapy was considered to accelerate the relief from fever and improvement of inflammatory symptoms and signs and CSF findings. The body temperature rose again in more than half of the patients receiving DXM, but fell to normal spontaneously without treatment. The elevation doubtlessly could not be distinguished from recurrence of the meningitis itself or complications. It seems to be likely that no treatment but careful observation is required even if the fever recurs as far as the CSF findings showed favorable progress with excelluent general conditions. When DXM is given, it is essential that CSF tests and culture are repeated during the early stages and the progress is monitored carefully.

Anti-Bacterial Agents↗
PubMed1999

Inhibitory effect of chalcone derivatives on recombinant human aldose reductase.

More than fifty chalcone derivatives were synthesized to examine structure-activity relationships against human aldose reductase. Certain 2',4'-dihydroxychalcone derivatives inhibited human aldose reductase activities, and 2',4',2, 4-tetrahydroxychalcone and 2',4',2-trihydroxychalcone showed potent inhibitory activity with IC50 values of 7.4x10(-9) M and 1.6x10(-7) M, respectively. On the other hand, cis-form chalcones, which were isomerized from the original trans-forms by irradiation of daylight in methanol solution, promoted the activity of human aldose reductase.

Aldehyde Reductase↗
PubMed1999

Effects of beta-blockers and nicardipine on oxotremorine-induced tremor in common marmosets.

Effects of beta-blockers (propranolol, arotinolol and nipradilol) and a Ca2+ channel blocker (nicardipine) on oxotremorine-induced tremor were studied in common marmosets. Generalized tremor was elicited by an intraperitoneal administration of 0.25 mg/kg oxotremorine. Intensity of the tremor was classified into 7 degrees, and it was evaluated every 10 min. The total intensity of oxotremorine-induced tremor for each drug was expressed as "points", which were the sum of tremor intensity scores evaluated every 10 min up to 190 min following the administration of oxotremorine. Beta-blockers significantly suppressed the tremor. On the other hand, the Ca2+ channel blocker exacerbated the tremor.

Adrenergic beta-Antagonists↗