Biomedical subjects

Y Urata

Publications and source records attributed to Y Urata.

At least 37 records · Page 2Linked to original sources

PubMed1998

Glutathione downregulates the phosphorylation of I kappa B: autoloop regulation of the NF-kappa B-mediated expression of NF-kappa B subunits by TNF-alpha in mouse vascular endothelial cells.

Nuclear factor-kappa B (NF-kappa B) regulates gene expression upon immune and inflammatory responses. It has been demonstrated that redox regulation by thiols is involved in the signal-transduction cascade. In this study, we examined the effect of glutathione (GSH) on the NF-kappa B activity and the expression of NF-kappa B subunits induced by tumor necrosis factor-alpha (TNF-alpha) using mouse vascular endothelial cells. GSH inhibited the serine phosphorylation of I kappa B-alpha by TNF-alpha, leading to the downregulation of NF-kappa B-DNA binding activity followed by decreased expression of p65/p50 and I kappa B mRNAs. The regulation of the autoregulatory loop for the NF-kappa B activation and the expression of NF-kappa B subunits may be important in endothelial cells in response to cytokines.

Animals↗

PubMed1998

Nuclear factor kappa B dependent induction of gamma glutamylcysteine synthetase by ionizing radiation in T98G human glioblastoma cells.

Glioblastoma is one of the most malignant of all neoplasms, and often shows resistance to chemotherapy and radiation therapy. Ionizing radiation activates transcriptional factors, such as nuclear factor kappa-B (NF-kappa B). Previously we found that glutathione (GSH) synthesis is induced by cytokines mediated by NF-kappa B (Urata et al. J. Biol. Chem., 1996). Here, we present direct evidence that NF-kappa B activated by ionizing radiation induces the expression of gamma-glutamylcysteine synthetase (gamma-GCS), the rate limiting enzyme of GSH synthesis, using T98G human glioblastoma cells. T98G cells have approximately 14-times the level of intracellular GSH of NB9 cells, radiation-sensitive neuroblastoma cells. In T98G cells, 30-Gy of ionizing radiation was required for the activation of NF-kappa B on an electrophoretic mobility shift assay and the induction of gamma-GCS mRNA on Northern blots and a nuclear run-on assay. However, when T98G cells were treated with buthionine sulfoximine, 3-Gy of ionizing radiation stimulated the DNA-binding activity of NF-kappa B and the expression of gamma-GCS. We constructed chimeric genes containing various regions of gamma-GCS promoter gene and the coding region for Luciferase. T98G cells transiently transfected with a plasmid containing the gamma-GCS promoter-luciferase construct showed increased luciferase activity when treated with ionizing radiation. The luciferase activity stimulated by ionizing radiation was found in the gamma-GCS promoter containing the NF-kappa B binding site, whereas not in that containing its mutated site. These results suggest that GSH synthesis is upregulated by ionizing radiation mediated by NF-kappa B and a high concentration of GSH in T98G cells causes downregulation of the NF-kappa B-DNA binding activity in response to ionizing radiation. The irresponsiveness of the intracellular signal transduction cascade to irradiation may be a factor in the resistance of T98G cells to radiation therapy.

Acetylcysteine↗

PubMed1998

Protective role of glutathione synthesis on radiation-induced DNA damage in rabbit brain.

1. Radiotherapy has attracted increasing interest in recent years. It is known that ionizing radiation induces oxygen radical injury, whereas oxidative stress by the radiation can cause cellular responses to defense cellular injury. In this study, the metabolism of antioxidants in response to ionizing radiation to the brain was studied in the brain using experimental rabbits. 2. Ionizing radiation to the hemicerebrum caused an increase in the levels of glutathione (GSH) and the activity of a GSH synthesizing enzyme, gamma-glutamylcysteine synthetase (gamma-GCS), and Cu,Zn-superoxide dismutase (Cu,Zn-SOD). Ionizing radiation also induced DNA-damage estimated by the formation of 8-hydroxydeoxyguanosine. These changes were dependent on the radiation dose. 3. Previous intrathecal-administration of buthionine sulfoximine (100 microM), a specific inhibitor of gamma-GCS, increased DNA damage by radiation in the radiated hemicerebrum. That of S-methyl GSH, on the other hand, resulted in a significant reduction of DNA damage by radiation. 4. These results suggest that synthesis of GSH and Cu,Zn-SOD is responsive to ionizing radiation and this induction of antioxidants may play a role in reducing tissue damage in radiotherapy.

Animals↗

PubMed1998

Inducible nitric oxide synthase is expressed in granuloma pyogenicum.

It is known that granuloma pyogenicum (GP) grows rapidly but cherry angioma (CA) does not, although they show the same histological features of hyperplasia of the capillary vessels. Although some cytokines have been thought to be angiogenic factors, a nitric oxide (NO) synthase-dependent effector mechanism is reported to be involved in macrophage-derived angiogenesis in humans. Under the hypothesis that this mechanism is also involved in the more rapid growth of GP, we examined the expression of inducible NO synthase (iNOS) in GP as compared with that in CA. The expression of iNOS mRNA was detected in GP, but not in CA, by reverse transcription-polymerase chain reaction (RT-PCR) analysis. In situ hybridization (ISH) demonstrated iNOS mRNA expression in endothelial cells and to a lesser extent round cells and spindle cells in the myxomatous stroma in GP. Immunohistochemical study showed that iNOS protein was expressed in endothelial cells, infiltrating round cells and spindle cells in the stroma in GP. These results suggested that a NOS-dependent mechanism may be involved in angiogenesis and the rapid growth of GP.

Adult↗

PubMed1998

Nicardipine normalizes elevated levels of antioxidant activity in response to xanthine oxidase-induced oxidative stress in hypertensive rat heart.

It has been reported that the production of oxygen radicals mediated by xanthine oxidase (XO) is stimulated in hypertensive cardiovascular endothelium, suggesting involvement of oxidative stress in pathogenesis of hypertension. In this study we estimated the effect of nicardipine, a calcium blocker, on the oxidative stress and antioxidant activities in left ventricles from spontaneously hypertensive rat (SHR) and stroke-prone SHR (SHRSP). The activity of XO increased 3.5-fold in SHR and 6.2-fold in SHRSP compared to that in normal controls (WKY). Interestingly, the levels of glutathione (GSH) and the activity of its synthesizing enzyme (gamma-glutamylcysteine synthetase, gamma-GCS) elevated concomitantly in SHR and SHRSP: the level of GSH increased 1.2-fold in SHR and 1.3-fold in SHRSP. The activity of gamma-GCS was elevated 1.5-fold in SHR and 2.4-fold in SHRSP, accompanying an increase in the expression of its mRNA. Treatment of these rats with nicardipine, for 4 weeks improved blood pressure, from 176 +/- 10 to 140 +/- 8 mmHg in SHR, and from 201 +/- 11 to 167 +/- 5 mmHg in SHRSP, respectively, and decreased wet weight of heart, levels of GSH, and the activities of XO and gamma-GCS. Nicardipine reduced the expression of gamma-GCS mRNA. Collectively, these results suggest that reactive oxygen species produced by XO in hypertensive rat heart cause induction of the expression of gamma-GCS and nicardipine plays a role in reducing the oxidative stress in hypertensive heart.

Animals↗

PubMed1998

Thermostable neutral protease resembling thermolysin derived from Bacillus brevis MIB001.

A microbe producing a protease with strong thermostability that was released extracellularly was isolated from soil. The isolate, MIB001, grew at from 15 to 51 degrees C and pH 5.1-8.8 and was tentatively identified as a strain of Bacillus brevis. Rabbit antisera raised against a pure preparation of the protease did not cross-react with thermolysin or neutral metalloprotease from Bacillus stearothermophilus KP1236.

Amino Acid Sequence↗

PubMed1998

Expression of inducible nitric oxide synthase and inflammatory cytokines in alveolar macrophages of ARDS following sepsis.

STUDY OBJECTIVE: The objective of this study was to evaluate the role of inducible nitric oxide synthase (iNOS) and proinflammatory cytokines in alveolar macrophages (AMs) in the pathogenesis of ARDS following sepsis. SETTING: ICU in a university hospital. DESIGN: Prospective exploratory, open-labeled study was carried out. PATIENTS: A total of 24 patients were investigated: 8 patients diagnosed as having ARDS following sepsis (ARDS group); 8 patients under general anesthesia in the operating room whose lung functions were normal (control group); and 8 patients who were intubated and artificially ventilated for 1 week in the ICU whose lung functions were not deteriorated without fulfilling the ARDS criteria and whose general state fulfilled the sepsis criteria (long-term ventilation group, or LTV group). MEASUREMENTS AND RESULTS: The expression of iNOS, interleukin-1beta (IL-1beta), interleukin-6 (IL-6), and interleukin-8 (IL-8) in AMs obtained from BAL fluid (BALF) was determined by the immunofluorescent technique. We observed the significant expression of iNOS, IL-6, and IL-8 only in the ARDS group. Meanwhile, NOx (the sum of NO2- + NO3-) was elevated in the BALF supernatant, and IL-6 and IL-8 levels in both the BALF supernatant and the serum were also elevated in the ARDS group. No significant expressions were detected in the control and the LTV group. CONCLUSIONS: The result that iNOS was detected only in ARDS patients following sepsis suggests that iNOS together with proinflammatory cytokines produced by AMs might play a pivotal role in the pathogenesis of acute lung injury and be useful for monitoring disorders in the lung in such conditions.

Adult↗

PubMed1998

High concentration of L-arginine suppresses nitric oxide synthase activity and produces reactive oxygen species in NB9 human neuroblastoma cells.

Hereditary argininemia manifests as neurological disturbance and mental retardation, features not observed in other amino acidemias. The cytotoxic effect of a high concentration of L-arginine (L-Arg) was investigated using NB9 human neuroblastoma cells (NB9), which express neuronal nitric oxide synthase (nNOS). When the concentration of L-Arg in the medium increased from 50 microM to 2 mM after incubation for 48 hr, the intracellular concentration of L-Arg increased from 68.0 +/- 1 pmol/10(6) cells to 1310.0 +/- 5 pmol/10(6) cells and that of L-citrulline (L-Cit) from undetectable levels to 47.1 +/- 0.2 pmol/10(6) cells (mean +/- SD of three independent analyses). This increase in intracellular L-Arg levels caused a decrease in NOS activity by approximately 71%. Flow cytometric analysis showed that reactive oxygen species (ROS) are produced in NB9 exposed to 2 mM L-Arg. The production of ROS was abolished by a NOS inhibitor, NG-nitro-L arginine-methylester. Production of ROS was also observed when NB9 were treated with L-Cit for 48 hr. To investigate the effect of L-Cit on the activity of NOS, a kinetic study on nNOS was conducted using cellular extracts from NB9. The apparent Km value of nNOS for L-Arg was 8.4 microM, with a Vmax value of 8.2 pmol/min/mg protein. L-Cit competitively inhibited NOS activity, as indicated by an apparent Ki value of 65 nM. These results suggest that L-Cit formed by nNOS in L-Arg-loaded neuronal cells inhibits NOS activity and nNOS in these L-Arg-loaded cells functions as a NADPH oxidase to produce ROS, which may cause neurotoxicity in argininemia.

Arginine↗

PubMed1997

Simultaneous activation of signals through gp130, c-kit, and interleukin-3 receptor promotes a trilineage blood cell production in the absence of terminally acting lineage-specific factors.

We assessed the biologic role of signaling through gp130, a signal-transducing receptor (R) component, in human hematopoiesis in vitro. Although peripheral blood-derived CD34(+) cells ubiquitously expressed gp130 and interleukin-3 receptor alpha (IL-3Ralpha), IL-6Ralpha was only detected on 80% of these CD34(+) cells. We sorted CD34(+)IL-6R+ or CD34(+)IL-6R- cells and studied the effect on hematopoietic colony formation of signaling through gp130 activated by IL-6 or a combination of IL-6 and recombinant soluble human IL-6R (sIL-6R) in the presence or absence of stem cell factor (SCF ) and/or IL-3. Signals activated by SCF, IL-6, or IL-6/sIL-6R complex alone did not induce significant colony formation. However, a combination of IL-3, SCF, and IL-6/sIL-6R complex dramatically induced many neutrophil (colony-forming unit-granulocyte [CFU-G]), erythroid burst (burst-forming unit-erythrocyte [BFU-E]), erythrocyte-containing mixed (CFU-Mix), and megakaryocyte (CFU-Meg) colony formations when CD34(+)IL-6R- cells were used as the target. CFU-G colony formation induced by the three signals was more evident when CD34(+)IL-6R+ cells were used as the target. This distinct synergistic effect of the three different signals was confirmed by single-cell clone-sorting experiments. Moreover, colony formation (including CFU-G, BFU-E, CFU-Mix, and CFU-Meg) was observed even in the presence of neutralizing antibodies for granulocyte colony-stimulating factor, erythropoietin, and thrombopoietin (c-Mpl), whereas neutralizing antibodies for gp130, IL-6R, IL-3, and SCF partially or completely blocked the synergistic effect. The maturation of neutrophilic, erythroid, and megakaryocytic cells supported by the three signals in serum-free cultures was confirmed by immunostaining using anti-CD66b, antiglycophorin A, antihemoglobin alpha, and anti-CD41 monoclonal antibodies, respectively. In contrast, any two of the three signals were insufficient for effective blood cell production in the absence of maturation factors. These results suggest that simultaneous activation of the three signals through gp130, c-kit, and IL-3R can induce in vitro proliferation and differentiation of trilineage hematopoietic progenitors in the absence of terminally acting lineage-specific factors.

Animals↗

PubMed1997

Oxygen-induced embryopathy and the significance of glutathione-dependent antioxidant system in the rat embryo during early organogenesis.

We investigated the effect of glutathione (GSH)-dependent antioxidant system against hydrogen peroxide (H2O2) formation in oxygen-induced embryopathy. Exposure of rat embryos to a high concentration of oxygen (20%) during early neurulation (day 9 to 10) significantly increased the incidence of neural tube defects compared with control embryos (10% vs 0%, p < 0.01) exposed to a low O2 concentration (5%). The concentration of GSH in 20% O2-exposed embryos was significantly reduced compared with that in control embryos (10.68 +/- 0.72 vs 12.34 +/- 0.65 nmol/mg protein, p < 0.001). The activity of gamma-glutamylcysteine synthetase (gamma-GCS), the rate-limiting GSH synthesizing enzyme increased in 20% O2-exposed embryos (24.83 +/- 0.71 vs 21.00 +/- 0.94 microunits/mg protein). Increased activity of gamma-GCS was associated with increased expression of gamma-GCS mRNA. Substantial increases were also observed in the activities of glutathione peroxidase (GPX) and glutathione S-transferase (GST) in 20% O2-exposed embryos. The formation of intracellular H2O2, measured by flow cytometer using 2',7'-dichlorofluorescein diacetate (DCFH-DA), increased in isolated embryonic cells of 20% O2-exposed embryos. The addition of buthionine sulfoxamine (BSO), a specific inhibitor of gamma-GCS, to culture media exposed to 20% O2 produced a marked decrease in the concentration of GSH in association with a further increase in the incidence of embryonic malformations (24.4% vs. 10%, P < 0.01). The addition of 2.0 mM GSH ester to culture media exposed to 20% O2 prevented the development of embryonic malformations through the restoration of normal GSH contents and reduction of H2O2. Our results demonstrated that oxygen-induced embryonic malformations were induced by increased production of H2O2 in the presence of an immature free radical scavenger system. We suggest that impaired responsiveness of the GSH dependent antioxidant system against oxidative stress plays a crucial role in oxygen-induced embryopathy.

Animals↗

PubMed1997

Pharmacokinetics and safety of JTP-4819, a novel specific orally active prolyl endopeptidase inhibitor, in healthy male volunteers.

AIMS: To investigate the pharmacokinetics and safety profile of JTP-4819, (-)-(2S)-1-benzylaminocarbonyl-[(2S)-2-glycoloylpyrrolidinyl ]-2-pyrrolidinecarboxamide, a novel specific orally active prolyl endopeptidase (PEP) inhibitor. METHODS: JTP-4819 was given orally to 28 healthy male volunteers at single doses of 30 mg (n = 6), 60 mg (n = 6), 120 mg (n = 6) and placebo (n = 3) and multiple doses of 60 mg three times daily (n = 5) and placebo (n = 2) for 7 days to investigate its safety and pharmacokinetics following a preliminary safety evaluation of 3, 10 and 30 mg doses in six healthy volunteers. With the single dose of 60 mg, a cross-over study was conducted to examine the effect of food on the bioavailability of the drug. The concentrations of JTP-4819 in plasma and urine were determined by electrospray ionization-liquid chromatography/mass spectrometry (ESI-LC/MS) method. RESULTS: In the multiple-dose study, the cholinesterase activity was gradually increased and reached above the normal range on days 4 to 8 in all five subjects given JTP-4819 and gradually returned to normal range after completion of dosing. The elevation of plasma cholinesterase activity was considered to be an action of JTP-4819, but this remains to be verified. There were no other abnormal findings in objective symptoms and laboratory findings including blood pressure, heart rate, electrocardiogram, body temperature, haematology, blood chemistry and urinalysis. The Cmax of JTP-4819 at 30, 60 and 120 mg in fasting state were 474, 887 and 1,649 ng ml-1, respectively, at 1 h after administration, and the t1/2 was about 2 h. AUC increased in proportion to the given doses. The cumulative urinary recoveries within 24 h were approximately 66%, Cmax, AUC, t1/2 and urinary recovery were not affected by food intake. In the multiple-dose study, there was no drug accumulation trend in plasma. CONCLUSIONS: These results indicate that JTP-4819 has acceptable pharmacodynamic and pharmacokinetics profiles for clinical use without any serious adverse events as we verified in healthy young male volunteers.

Administration, Oral↗

PubMed1997

[A fatal case of overwhelming postsplenectomy infection syndrome developing 10 years after splenectomy].

UNLABELLED: Splenectomized patients are likely to suffer from severe infections, such as sepsis and meningitis. This syndrome is called overwhelming postsplenectomy infection (OPSI) in Europe and America. The course is rapid, the clinical symptoms are serious, and the prognosis is very poor. We treated one adult patient with OPSI syndrome that developed 10 years after splenectomy. CASE: A 26-year-old man had undergone a splenectomy following a traffic accident 10 years previously. On January 7, 1996, he had diarrhea and nausea. On January 10, he became drowsy and presented at our hospital with multiple organ failure. He underwent hemodialysis and plasmapheresis because of acute renal failure and also received immune globulin, antibiotics and prednisolone. However, these medications were not effective. He died 7 hours later. We identified diplococcus on a blood smear, IgG 3 deficiency and a low titer of specific pneumococcal IgG 2 antibody. The autopsy findings included bilateral acute hemorrhagic necrosis of the adrenal glands (Waterhouse-Friderichsen syndrome).

Adult↗

PubMed1997

Effects of JTV-506, a new K+ channel activator, on airway smooth muscle contraction and systemic blood pressure.

BACKGROUND: ATP-sensitive K+ (KATP) channel activators produce relaxation of smooth muscle in many tissues. However, this wide range of effects restricts their clinical usefulness in bronchial asthma because of a reduction in systemic blood pressure. METHODS: We have now examined the effects of JTV-506, a new benzopyran derivative, on airway smooth muscle contraction and systemic blood pressure and have compared this compound with cromakalim. We measured isometric tension records from guinea-pig isolated trachea, as well as the respiratory resistance (Rrs) and systemic blood pressure in anesthetized guinea-pigs. RESULTS: JTV-506 caused a concentration-dependent inhibition of histamine-induced contraction in guinea-pig isolated tracheal smooth muscle, and was antagonized by glibenclamide. JTV-506 was 7.6-fold more potent than cromakalim. In anesthetized animals the intravenous injection of JTV-506 reduced the increase in Rrs induced by intravenous application of 5 micrograms/kg of histamine in a dose-dependent manner. 10 micrograms/kg of JTV-506 resulted in 57.0 +/- 17.9% inhibition of the increase in Rrs at 10 min. The inhibitory action on Rrs disappeared after 60 min. 10 micrograms/kg of cromakalim caused 25.4 +/- 5.8% inhibition of the increase in Rrs induced by histamine at 1 min. The ED50 values for JTV-506 and cromakalim were 6.7 +/- 3.5 micrograms/kg and 60.1 +/- 15.8 micrograms/kg, respectively (P < 0.05). Cromakalim was approximately 9-fold less potent in inhibiting the increased Rrs by histamine, and the inhibitory action lasted less than 10 min. The reduction of systemic blood pressure by JTV-506 and cromakalim (each at a dose of 10 micrograms/kg iv) was 11.3% and 21.5%, respectively (P < 0.05). CONCLUSION: JTV-506 inhibits histamine-induced contraction of tracheal smooth muscle by activation of KATP channels. This compound is more potent and longer-lasting in the suppression of histamine-induced increases in Rrs, and is less hypotensive than cromakalim. Our results suggest that this compound merits further investigation for utility as a bronchodilator in the clinic.

Animals↗

PubMed1997

Protocols to demonstrate slowing of Alzheimer disease progression. Position paper from the International Working Group on Harmonization of Dementia Drug Guidelines. The Disease Progression Sub-Group.

Two suggested clinical trial designs for assessing progression of Alzheimer disease are the randomized withdrawal design and the randomized start design. The most promising of these, the randomized start design, has the potential to demonstrate a delay in progression, but there remain problematic design, ethical, and statistical issues to be solved before the protocol can be used in a clinical trial. The development of biological markers of the disease process using neuroimaging or other measures also may provide a robust method of measuring disease progression and demonstrating the biological effect of a drug on the disease process.

Aged↗

PubMed1997

Human erythropoietin receptor increases GATA-2 and Bcl-xL by a protein kinase C-dependent pathway in human erythropoietin-dependent cell line AS-E2.

Erythropoietin (Epo) is a cytokine known to stimulate proliferation and differentiation of erythroid cells. However, recent gene disruption experiments demonstrated that Epo receptor signaling is not an obligatory step in erythroid differentiation. Here, we describe the role of Epo in proliferation, terminal differentiation, and apoptosis in a novel human Epo-dependent cell line, AS-E2. Upon withdrawal of Epo, the cells ceased to proliferate and underwent apoptotic death. Accompanying this cell death, an increase in the number of hemoglobin-positive cells of approximately 2-fold was observed. This was associated with immediate up-regulation of the GATA-1:GATA-2 ratio and down-regulation of Bcl-xL. Treatment with Epo or 12-O-tetradecanoyl-phorbol-13-acetate (TPA) up-regulated expression of GATA-2 and Bcl-xL, and these elevations were inhibited by inhibitors of protein kinase C (PKC), H7 and H8. HA1004, a structural analogue of H7 but a poor inhibitor of PKC, had no inhibitory effect. Therefore, in AS-E2 cells, it is likely that Epo plays a role in (a) proliferation, (b) inhibition of differentiation, and (c) survival, by maintaining GATA-2 and Bcl-xL expression through activation of PKC.

Apoptosis↗

PubMed1996

Long exposure to high glucose concentration impairs the responsive expression of gamma-glutamylcysteine synthetase by interleukin-1beta and tumor necrosis factor-alpha in mouse endothelial cells.

To elucidate the pathological metabolism of glutathione synthesis in diabetic endothelial cells, we studied the expression of gamma-glutamylcysteine synthetase (gamma-GCS) using a mouse vascular endothelial cell line. Exposing normoglycemic endothelial cells to tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta (IL-1beta) increased the activity and the mRNA expression of gamma-GCS. The addition of inhibitors for nuclear factor kappaB (NF-kappaB) to the cells caused a loss of the gamma-GCS mRNA expression in response to TNF-alpha. A shift of the concentration of glucose in the medium from 5.5 to 28 mM glucose and a following incubation for 7 days decreased the expression of gamma-GCS mRNA. These cells showed no apparent responses of gamma-GCS mRNA or the activity of NF-kappaB to TNF-alpha or IL-beta. Increase in the GSH concentration of the cells treated with 28 mM glucose restored the expression of gamma-GCS mRNA and its response to TNF-alpha or IL-beta, suggesting that redox regulation is involved in the expression of gamma-GCS. In summary, the expression of gamma-GCS is regulated by TNF-alpha or IL-1beta in endothelial cells mediated by NF-kappaB stimulation, and impairment of the regulation of gamma-GCS in hyperglycemic cells may be a cause of medical complications that develop in diabetes mellitus.

Adenosine Triphosphate↗

PubMed1996

Relation of oxidative stress and glutathione synthesis to CD95(Fas/APO-1)-mediated apoptosis of adult T cell leukemia cells.

An IL-2 dependent adult T cell leukemia cell line (SO4) has been established that is sensitive to CD95-mediated apoptosis as well as a subline (R-SO4) that is resistant. Incubating SO4 cells with anti-CD95 IgM mAb caused concentration-dependent cell death. On the contrary, R-SO4 cells did not die even at 1000 ng/ml of anti-CD95 IgM mAb. The levels of CD95 expression on R-SO4 cells were one-third of those on SO4 cells. However a blocking Ab, anti-CD95 IgG mAb, did not induce complete resistance of SO4 cells to anti-CD95 IgM mAb as R-SO4 cells. As CD95 and TNF receptor are similar, and TNF/TNF receptor binding induces oxygen radicals, the involvement of oxidant and antioxidant systems in CD95-mediated apoptosis has been examined. The addition of anti-CD95 IgM mAb resulted in formation of intracellular oxygen radical species in the SO4 cells as measured using 2',5',-dichlorofluorescein as substrate. The oxygen radical production induced DNA damage as determined by formation of 8-hydroxydeoxyguanosine. No increase in the formation of oxygen radicals was observed in R-SO4 cells. Concentrations of the intracellular antioxidant, glutathione, and the key enzyme for its synthesis, gamma-glutamylcysteine synthetase, were 150% increased in R-SO4 cells in comparison with that of SO4 cells. Moreover, glutathione ester decreased the formation of 8-hydroxydeoxyguanosine. These results suggested that apoptosis mediated by CD95 in ATL cells is related to the production of oxygen radical species and cellular antioxidant systems, especially, glutathione synthesis.

Apoptosis↗

PubMed1996

Impairment of antioxidants in colonic epithelial cells isolated from trinitrobenzene sulphonic acid-induced colitis rats. Protective effect of rebamipide.

BACKGROUND: The functional status of glutathione, its related enzymes, and Cu,Zn-superoxide dismutase in colonocytes isolated from rats with trinitrobenzene sulphonic acid-induced colitis, and the effect of rebamipide (a scavenger) on these antioxidants and on colitis, were studied. METHODS: The rats were treated with rebamipide, killed on day 14, and compared with controls. Glutathione and enzymatic activities were spectrophotometrically estimated. The effect of rebamipide on colitis was also assessed histologically and by myeloperoxidase activity. RESULTS: In controls the concentration of glutathione and the activities of glutathione S-transferase and Cu,Zn-superoxide dismutase were decreased, but that of glutathione peroxidase was increased. Rebamipide prevented the impairment of these enzymes, restored the concentration of glutathione, and attenuated (low damage scores and myeloperoxidase activity) the severity of the colitis. CONCLUSIONS: These features suggest that the impairment of antioxidants is closely related to the development of the inflammatory lesions, and rebamipide has a beneficial effect on experimental colitis.

Alanine↗