Biomedical subjects

Yasuhiro Ogawa

Publications and source records attributed to Yasuhiro Ogawa.

At least 37 records · Page 2Linked to original sources

PubMed2005

Relationship between hormonal receptors, HER-2, p53 protein, Bcl-2, and MIB-1 status and the antitumor effects of neoadjuvant anthracycline-based chemotherapy in invasive breast cancer patients.

PURPOSE: The purpose of this study was to evaluate the predictive value of six different biological factors for neoadjuvant chemotherapy (NAC) in breast conservation treatment (BCT) for invasive breast cancer. MATERIALS AND METHODS: Thirty invasive breast cancer patients (31 breasts) who received NAC as BCT and needle biopsy before chemotherapy were included in this study. Breast cancer tissue was obtained with an 18G core needle with ultrasound guidance. Patients received two to five courses of CAF (cyclophosphamide 600 mg/m(2), pirarubicin 20-40 mg, 5-fluorouracil 600 mg/m(2)). Tissue sections from formalin-fixed paraffin-embedded blocks were stained for the presence of estrogen receptor (ER), progesterone receptor (PgR), HER (human epidermal growth factor receptor)-2, p53 protein, Bcl-2, and MIB-1 (Ki-67). Tumor reduction rate was assessed by MRI before and after chemotherapy. RESULTS: The tumor reduction rate did not differ according to the number of courses of chemotherapy administered. In both the univariate and multivariate analyses, HER-2-negative status was the only significant predictive factor of response (P<0.05). There was no correlation between response and hormone receptors, MIB-1, p53 protein, or Bcl-2 expression. CONCLUSION: This study suggests that breast cancer cells that overexpress HER-2 may be resistant to low-doses of anthracycline-based chemotherapy.

Adult↗

PubMed2004

Mitochondrial transmembrane potential is diminished in phorbol myristate acetate-stimulated peritoneal resident macrophages isolated from wild-type mice, but not in those from gp91-phox-deficient mice.

Macrophages produce superoxide (O2-) during phagocytosis or upon stimulation with a variety of agents including phorbol myristate acetate (PMA) through the activation of NADPH oxidase, and the formed O2- is converted to other reactive oxygen species (ROS) such as hydrogen peroxide (H2O2). The aim of the present study was to elucidate the effect of the intracellularly produced ROS on mitochondrial transmembrane potential (MTP) in mouse (C57BL/6) peritoneal resident macrophages stimulated with PMA. Using a fluorescent dye, succinimidyl ester of dichlorodihydrofluorescein (H2DCFDA), O2- was visualized in intracellular compartments in a certain subpopulation of macrophages isolated from wild-type mice. Cells deficient in gp91-phox, one of the membrane components of NADPH oxidase, were negative for the fluorescence. When cells were loaded with both H2DCFDA and MitoCapture, a fluorescent dye for mitochondria, mitochondrial fluorescence was diminished in O2- -producing cells, but not in O2- -deficient cells. Flow cytometry also revealed the decrease of mitochondrial fluorescence in wild-type cells, but not in gp91-phox-deficient cells. The loss of mitochondrial fluorescence was prevented by microinjection of catalase into cells. The present findings demonstrate that MTP is diminished by ROS, including the H2O2 dismutated from O2-, produced intracellularly by activation of the NADPH oxidase in mouse peritoneal resident macrophages stimulated with PMA.

Animals↗

PubMed2004

Histopathologic amelioration of fibroproliferative change in rat irradiated lung using soluble transforming growth factor-beta (TGF-beta) receptor mediated by adenoviral vector.

PURPOSE: To investigate whether an adenoviral-mediated soluble transforming growth factor-beta (TGF-beta) type II receptor could ameliorate fibroproliferative change in rat irradiated lung. METHODS AND MATERIALS: We used an adenoviral vector expressing a soluble TGF-beta receptor (AdT beta-ExR), which adsorbs TGF-beta and inhibits the function of the wild-type receptor as a dominant-negative mutant. Rats were i.v. injected with either 0.5 mL of AdT beta-ExR (1.0 x 10(9) plaque-forming units/mL) or AdLacZ (1.0 x 10(9) plaque-forming units/mL), a control adenovirus expressing bacterial beta-galactosidase, or saline, then 3 days later they received 4-MV X-ray irradiation of 30 Gy in a single fraction to the right lung. Eight weeks after irradiation, the rats were killed, and their right lungs were examined histopathologically. The respiratory rates of all rats were observed with a charge-coupled device video system before the rats were irradiated and killed. RESULTS: A significant increase in breathing rates was observed in the saline- or AdLacZ-infected rats. The respiratory rate of the AdT beta-ExR-treated rats was significantly lower than that in the saline- or AdLacZ-infected rats. Fibroproliferative change in the irradiated lung was markedly reduced in the AdT beta-ExR-treated rats in comparison with the saline- or AdLacZ-infected rats. With respect to active TGF-beta 1 expression, myofibroblast proliferation, and macrophage/monocyte infiltration, the findings were identical to those for fibroproliferative change. CONCLUSIONS: Our results indicate that TGF-beta plays a critical role in radiation-induced fibroproliferation of the lung and suggest that the adenoviral-mediated soluble TGF-beta receptor may have potential for use in the amelioration of this intractable pulmonary damage.

Adenoviridae↗

PubMed2004

Reactive oxygen species-producing site in radiation-induced apoptosis of human peripheral T cells: involvement of lysosomal membrane destabilization.

In our previous studies, we have partly elucidated the mechanism of radiation-induced apoptosis of human peripheral T cells. The exact site of the ROS (reactive oxygen species) formation induced by irradiation has been so far unknown. Therefore, in this study, we investigated the site of ROS formation by utilizing MitoCapture, H2DCFDA (succinimidyl ester of dichlorodihydrofluorescein diacetate), DAPI, and Lysosensor. Our results showed that ROS formation apparently originated in the mitochondria and/or lysosomes instead of in the nuclei of irradiated T cells. Moreover, lysosomal swelling and deformity, possibly revealing lysosomal membrane instability, were observed at 1 h after 5 Gy irradiation of T cells. At 4 h after irradiation of 5 Gy, increase of fluorescence around the lysosomes, possibly revealing lysosomal rupture, was seen. Based on the above results, we concluded the possible existence of a new apoptotic cascade involving early lysosomal membrane destabilization in radiation-induced apoptosis of human peripheral T cells. Therefore, possible involvement of lysosomal protease leakage caused by hydroxyl radical formation in lysosomes (possibly resulting in mitochondrial membrane dysfunction) is considered to play an important role in radiation-induced T cell apoptosis.

Apoptosis↗

PubMed2004

Primary toremifene treatment for elderly postmenopausal women with breast cancer.

Among patients with breast cancer who consulted the Department of Radiology, Kochi Medical School to undergo breast-conservation treatment, toremifene (TOR) alone was administered to 7 postmenopausal women as initial treatment for reasons such as the patient's desire, advanced age, and concomitant disease. In 6 patients, breast-conserving surgery was performed 1-12 months after the start of the administration of TOR alone. A 90-year-old patient has been treated with TOR alone for 56 months, and is being followed up. Six of 7 patients showed 50% or greater reduction of tumors, including 1 in whom the administration of TOR alone for 5 months reduced the tumor from a clinical diagnosis of skin invasion (T4b) to T1c, allowing lumpectomy under local anesthesia. In one patient, there were no changes (reduction ratio: 14%). No progressive disease was detected in any patient. In this study, the administration of TOR alone markedly reduced tumors in patients with estrogen receptor (ER)-positive breast cancer, facilitating down-staging. Treatment with TOR alone may be a useful neoadjuvant therapy or single therapy in elderly patients.

Aged↗

PubMed2004

Reactive oxygen species-producing site in hydrogen peroxide-induced apoptosis of human peripheral T cells: involvement of lysosomal membrane destabilization.

In our previous study, we examined the effect of exogenous hydrogen peroxide, which causes a potent oxidative stress and has been demonstrated to be a potent apoptosis-inducer in many kinds of cells. We found that the addition of 1 or 10 mM hydrogen peroxide induced reactive oxygen species (ROS) formation, oxidative DNA damage, dysfunction of the mitochondrial membrane potential, and early apoptotic changes in the human osteosarcoma cell line HS-Os-1. We therefore concluded that intracellular ROS formation was involved in the hydrogen peroxide-induced apoptosis of HS-Os-1 cells. In contrast to the osteosarcoma cell line HS-Os-1, human peripheral T cells are considered to be easily susceptible to oxidative stress, because these cells lack peroxidase activity. Therefore, in this study, we investigated the site of ROS formation by utilizing MitoCapture, H2DCFDA (succinimidyl ester of dichloro-dihydrofluorescein diacetate), DAPI (4',6-diamidino-2-phenylindole), and LysoSensor. Our results showed that ROS formation was apparently diffusely distributed in T cells oxidatively stressed with 0.1 mM hydrogen peroxide. Moreover, lysosomal swelling and deformity, possibly revealing lysosomal membrane destabilization, were observed in these cells. Based on the above results, there exists an apoptotic cascade involving early lysosomal membrane destabilization in the hydrogen peroxide-induced apoptosis of human peripheral T cells. Therefore, the possible involvement of lysosomal protease leakage caused by hydroxyl radical formation in lysosomes (possibly resulting in mitochondrial membrane dysfunction) is considered to play an important role in hydrogen peroxide-induced T cell apoptosis.

Apoptosis↗

PubMed2004

Reactive oxygen species-producing site in radiation and hydrogen peroxide-induced apoptosis of human peripheral T cells: Involvement of lysosomal membrane destabilization.

In our previous studies, we showed that the apoptotic resistance of the human osteosarcoma cell line HS-Os-1 against irradiation was easily converted to a state of apoptotic-susceptibility by the addition of a relatively low concentration of hydrogen peroxide to the culture medium just prior to irradiation. When we consider the combined use of radiotherapy and hydrogen peroxide in a clinical setting for patients with radioresistant neoplasms, we need to be careful of the possible augmentation of the radiation effect to normal tissues of patients who undergo radiation therapy for their tumor in the presence of a low concentration of hydrogen peroxide in their topical tumor tissue. Therefore, we examined the combined effect of irradiation and hydrogen peroxide compared to that of irradiation alone for human peripheral T cells which were considered to be representative of normal tissue susceptible to apoptosis induced by irradiation. In this study, we compared the morphological changes in human peripheral T cells between both groups by utilizing MitoCapture, H2DCFDA (succinimidyl ester of dichloro-dihydrofluorescein diacetate), DAPI (4',6-diamidino-2-phenylindole), and LysoSensor. Our results showed that ROS formation was apparently augmented in the mitochondria and/or lysosomes instead of in the nuclei of irradiated T cells in the presence of a low concentration of hydrogen peroxide compared to those treated with irradiation alone. Moreover, dysfunction of mitochondrial membrane potential was also more evidently shown in human peripheral T cells irradiated under existence of a low concentration of hydrogen peroxide compared to T cells treated with 5 Gy irradiation alone. Based on these results, we concluded the possible existence of an augmentation effect of irradiation by the existence of a low concentration of hydrogen peroxide for human peripheral T cells. Therefore, we should be alert for the combined effects of radiation therapy and hydrogen peroxide on normal tissues in possible clinical situations when this combination is used for treatment of patients having radioresistant neoplasms such as osteosarcoma, malignant melanoma, and glioblastoma multiforme.

Apoptosis↗

PubMed2004

The role of selective COX-2 inhibitors in reactive oxygen species formation in osteosarcoma cells after X-ray irradiation.

Selective inhibition of COX-2 is thought to prevent carcinogenesis in some malignant tumors. In this study, in an effort to enhance the effectiveness of osteosarcoma treatment, we investigated the effect of a selective inhibitor of COX-2, with or without irradiation. We also asked whether selective COX-2 inhibitors increase the effect of X-ray irradiation, with regard to reactive oxygen species (ROS) formation in an osteosarcoma cell line. Our results showed that the presence of COX-2 inhibitor without irradiation results in faint spots of ROS formation that do not appear in the absence of COX-2 inhibitor. However, COX-2 inhibitor did not induce ROS formation when combined with irradiation. Thus, radiotherapy with selective COX-2 inhibitions has limitations in the treatment of radioresistant osteosarcoma to obtain the effective achievement, it is indispensable to combine another agent in future studies.

Cell Line, Tumor↗

PubMed2004

Cross talk between COX-2 inhibitor and hyaluronic acid in osteoarthritic chondrocytes.

Both hyaluronic acid (HA) and cyclooxygenase-2 (COX-2) inhibitors are used in clinical practice in the treatment of osteoarthritis. There have been no reports regarding cross-talk between HA and COX-2 inhibitors in articular human chondrocytes. The purpose of this study was to investigate whether HA, COX-2 inhibitors or a combination of COX-2 inhibitors and HA have different effects in human articular between lower and highly degenerated chondrocytes. Isolated lower and highly degenerated chondrocytes were divided into 5 groups: ethanol (used as a control for the solvents), HA, COX-2 inhibitors, COX-2 inhibitors plus HA, or no additive. After incubating for 48 h, mitochondrial membrane potential analysis and western blotting of p38 and p44/42 mitogen-activated protein kinase (MAPK) were performed. Glycosaminoglycan, nitric oxide (NO) production and prostaglandin E2 (PGE2) concentrations were assessed. A combination of COX-2 inhibitors and HA resulted in dendritic, proliferating chondrocytes with strong red fluorescence enriched in the mitochondrial membrane, and indicated reduction of apoptosis in chondrocytes. COX-2 inhibitors alone, and a combination of COX-2 inhibitor and HA inhibited the activation of p38 in highly degenerated chondrocytes. A combination of COX-2 inhibitors and HA decreased NO production in highly degenerated chondrocytes. COX-2 inhibitors decreased PGE2 production, however, HA alone had no effect on PGE2 production. The present study demonstrated that COX-2 inhibitors and HA interacted synergistically the MAPK pathway and inhibition of NO production in highly degenerated chondrocytes. Administration of COX-2 inhibitors plus HA could be used as a new alternative way of treating osteoarthritis.

Adjuvants, Immunologic↗

PubMed2004

Lysosomal dysfunction on hydrogen peroxide-induced apoptosis of osteoarthritic chondrocytes.

The purpose of this study was to examine the mechanism of hydrogen peroxide-induced apoptosis in osteoarthritic chondrocytes. We evaluated the reactive oxygen species (ROS) formation, lysosomal staining and dysfunction of the mitochondrial membrane potential in these cells after exposure to hydrogen peroxide. Osteoarthritic chondrocytes were isolated, and divided into 4 dishes in which different concentrations (0.1 mM, 1 mM and 10 mM) of hydrogen peroxide, or no additive (control) was added. The cells were incubated for 1 or 4 h, then assayed for ROS formation, mitochondrial membrane potential and lysosomal staining. ROS formation was detected in chondrocytes after 1 h of exposure to hydrogen peroxide concentrations over 0.1 mM. Lysosomal swelling was detected after 1 h of exposure to hydrogen peroxide concentrations of 0.1 mM and over, possibly revealing lysosomal membrane instability. Moreover, indications of lysosomal rupture, including release of lysosomal enzymes, were apparent 1 h after addition of 10 mM of hydrogen peroxide. The addition of hydrogen peroxide to chondrocytes induces ROS formation and lysosomal dysfunction, revealed by swelling and rupture, prior to dysfunction of the mitochondrial membrane potential. Anti-oxidants may have a therapeutic application in the prevention of lysosomal dysfunction to inhibit chondrocyte apoptosis and degradation of the cartilage matrix.

Antioxidants↗

PubMed2004

Immunocytochemical characteristics of human osteosarcoma cell line HS-Os-1: possible implication in apoptotic resistance against irradiation.

In our previous study, we examined reactive oxygen species (ROS) formation in T lymphocytes following 5 Gy irradiation. We found that ROS formation occurred immediately after irradiation, continued for several hours, and resulted in oxidative DNA damage. Therefore, the origin of the hyper-radiosensitivity of T lymphocytes seemed to be the high production of ROS in the mitochondrial DNA following irradiation. In the succeeding study, we examined radiation-induced ROS formation, oxidative DNA damage, early apoptotic changes, and mitochondrial membrane dysfunction in the human osteosarcoma cell line HS-Os-1. We found that ROS formation and oxidative DNA damage were actually scarcely seen after irradiation of up to 30 Gy in these cells, that mitochondrial membrane potential was preserved, and that apoptotic changes were not demonstrated despite the relatively high-dose irradiation of 30 Gy. In the present study, we examined the immunocytochemical characteristics of the apoptotic-resistance of the HS-Os-1 cell line against irradiation in order to clarify its possible implications regarding radiosensitivity. The results showed that these cells lack P53 and Bax protein expression, and strong peroxidase activity was confirmed in the nuclei of the cells. Moreover, SODII (manganese superoxide dismutase II) protein expression was gradually increased in spite of irradiation of up to 30 Gy. Therefore, it is concluded that HS-Os-1 cells are originally apoptotic-resistant and that the cells possess a strong ability to scavenge for free radicals. To convert these cells to a state of apoptotic-susceptibility, a powerful oxidant such as hydrogen peroxide might exert such an effect in terms of the production of hydroxyl radicals in lysosomes in the cells as shown in our previous studies. The origin of the radioresistance of the human osteosarcoma cell line HS-Os-1 is considered to to be low degree of ROS formation following irradiation, reflecting the strong scavenging ability of these cells for free radicals including hydroxyl radicals.

Apoptosis↗

PubMed2004

A combination of selective COX-2 inhibitors and hydrogen peroxide increase the reactive oxygen species formation in osteosarcoma cells after X-ray irradiation.

We investigated whether a combination of selective COX-2 inhibitors and hydrogen peroxide increases the effect of X-ray irradiation, with regard to reactive oxygen species (ROS) formation in an osteosarcoma cell line. COX-2 inhibitor did not induce ROS formation when combined with irradiation. A low dose concentration of COX-2 inhibitor in combination with hydrogen peroxide and irradiation did affect ROS formation in the intracellular compartment; however, this same combination of agents at high doses did not modulate the effect of irradiation. Therefore, low doses of COX-2 inhibitor and hydrogen peroxide together, in combination with irradiation, is a potentially useful alternative form of radiotherapy for apoptotic-resistant neoplasms such as osteosarcoma.

Celecoxib↗

PubMed2004

Endothelial nitric oxide synthase and methylenetetrahydrofolate reductase gene polymorphisms are associated with endothelial dysfunction in young, healthy men.

BACKGROUND: The guanine to thymine polymorphism at position 894 of the eNOS gene (resulting in a change from glutamate to aspartate [Asp] at codon 298 [Asp298]) and the methylenetetrahydrofolate reductase (MTHFR) gene polymorphism (C677T) have been reported to be associated with atherosclerosis and cardiovascular disease. Endothelial dysfunction is considered to be the earliest stage of atherosclerosis. OBJECTIVES: To examine whether common eNOS and MTHFR gene polymorphisms are associated with endothelial dysfunction in young, healthy men without overt cardiovascular disease. SUBJECTS AND METHODS: Flow-mediated, endothelium-dependent vasodilation (FMD) and glyceryl trinitrate-induced, endothelium-independent vasodilation (GTN) were measured using high-resolution ultrasound of the brachial artery in 53 young, healthy men assigned to eNOS and MTHFR genotypes. RESULTS: Subjects with the eNOS Asp298 allele (n=15) showed significantly reduced FMD:GTN compared with those without this allele (n=38) (0.23+/-0.13 [mean +/- SD] versus 0.35+/-0.14, P=0.0072), whereas there was no significant difference in GTN between these two groups. Although subjects with the MTHFR T677 allele did not show significantly reduced levels of FMD:GTN, subjects with the eNOS Asp298 allele and who were carriers of the MTHFR T677 allele demonstrated markedly reduced levels of FMD:GTN compared with noncarriers (0.14+/-0.05 versus 0.28+/-0.13, P=0.04). CONCLUSIONS: The data suggest that even in young men, the eNOS Asp298 allele may be involved in endothelial dysfunction before any overt vascular disease has occurred. Furthermore, a combination of the eNOS Asp298 and MTHFR T677 alleles may exaggerate endothelial dysfunction and may contribute to a comparatively earlier development of atherosclerosis.

Adult↗

PubMed2004

Prevention of hydrogen peroxide-induced apoptosis of human peripheral T cells by a lysosomotropic iron chelator, ammonium chloride.

Human peripheral T cells are considered to be easily susceptible to oxidative stress because these cells lack peroxidase activity. Therefore, in a previous study, we investigated the site of ROS formation by utilizing Mito-Capture, H(2)DCFDA (succinimidyl ester of dichlorodihydrofluorescein diacetate), DAPI (4',6-diamidino-2-phenylindole), and LysoSensor. Our results showed that ROS formation was apparently diffusely distributed in T cells oxidatively stressed with 0.1 mM hydrogen peroxide. Moreover, lysosomal swelling and deformity, possibly revealing lysosomal membrane destabilization, were observed in these cells. Based on the above-mentioned results, we concluded that an apoptotic cascade involving early lysosomal membrane destabilization exists in the hydrogen peroxide-induced apoptosis of human peripheral T cells. Therefore, the possible involvement of lysosomal protease leakage caused by hydroxyl radical formation in lysosomes (possibly resulting in mitochondrial membrane dysfunction) is considered to play an important role in hydrogen peroxide-induced T cell apoptosis. Hydrogen peroxide-mediated destabilization of lysosomal membranes with release of hydrolytic enzymes such as many kinds of cathepsins into the cell cytoplasm can lead to a cascade eventuating in cell death. To assess the importance of the intralysosomal pool of redox-active iron, we examined the effect of blockade of lysosomal digestion by exposing T cells to the lysosomotropic alkalinizing agent ammonium chloride (NH(4)Cl). Preincubation of human peripheral T cells with 10 mM NH(4)Cl for 4 h dramatically decreased apoptotic death caused by subsequent exposure to hydrogen peroxide (H(2)O(2)), and lysosomes and mitochondria showed almost normally preserved appearance. Therefore, we concluded here that lysosomal protease leakage caused by hydrogen peroxide in T cells was prevented by preincubation with ammonium chloride (NH(4)Cl).

Ammonium Chloride↗

PubMed2004

Utility of initial MRI for predicting extent of residual disease after neoadjuvant chemotherapy: analysis of 70 breast cancer patients.

This study was performed to evaluate the utility of initial MRI in predicting the extent of residual disease following neoadjuvant chemotherapy (NAC). The study population consisted of 70 patients with breast cancer (unilateral, n=69; bilateral, n=1) (mean age 51 years) who underwent magnetic resonance imaging (MRI) with gadolinium enhancement both before and after NAC. Basic NAC was comprised of cyclophosphamide, pirarubicin, and 5-fluorouracil. MRI features were compared with pathological diagnosis following surgery. MRI features of breast cancer before NAC were classified as either solitary nodular (SN) (n=33) (47%), or multiple nodular and/or unlocalized dendritic (MN/UD) (n=38) (53%). MRI typing was independent of NAC in 68 tumors (SN, n=32; MN/UD, n=36) (96%, p<0.0001). All except one of the 33 SN tumors (97%) displayed negative margins. In addition, 5 of the 33 SN tumors (15%) displayed pathological complete response (pCR). Conversely, all 5 requiring total glandectomy due to wide infiltration and all except one of the 17 (94%) displaying positive margins necessitating extended resection were classified as MN/UD. Only SN-type tumors on initial MRI have the possibility of pCR after NAC. MN/UD tumors could possess margins necessitating expanded excision or total glandectomy. Morphological concepts based on MRI can prove useful in surgical planning and predicting the extent of residual disease after NAC.

Adult↗

PubMed2003

The potential to induce glial differentiation is conserved between Drosophila and mammalian glial cells missing genes.

Drosophila glial cells missing (gcm) is a key gene that determines the fate of stem cells within the nervous system. Two mouse gcm homologs have been identified, but their function in the nervous system remains to be elucidated. To investigate their function, we constructed retroviral vectors harboring Drosophila gcm and two mouse Gcm genes. Expression of these genes appeared to influence fibroblast features. In particular, mouse Gcm1 induced the expression of astrocyte-specific Ca(2+)-binding protein, S100beta, in those cells. Introduction of the mouse Gcm1 gene in cultured cells from embryonic brains resulted in the induction of an astrocyte lineage. This effect was also observed by in utero injection of retrovirus harboring mouse Gcm1 into the embryonic brain. However, cultures from mouse Gcm1-deficient mouse brains did not exhibit significant reductions in the number of astrocytes. Furthermore, in situ hybridization analysis of mouse Gcm1 mRNA revealed distinct patterns of expression in comparison with other well-known glial markers. The mammalian homolog of Drosophila gcm, mouse Gcm1, exhibits the potential to induce gliogenesis, but may function in the generation of a minor subpopulation of glial cells.

Animals↗

PubMed2003

Protective effect of 3-methyl-1-phenyl-2-pyrazolin-5-one, a free radical scavenger, on acute toxicity of paraquat in mice.

Paraquat poisoning results in damages of multiple organs including liver, kidney and lung, and antioxidants have been proven to have protective effects. As a novel free radical scavenger, 3-methyl-1-phenyl-2-pyrazolin-5-one (MCI-186), was introduced to clinical use recently, its protective effect was studied on acute toxicity of paraquat in male ddY mice. When paraquat (175 mg/kg) were given orally, the survival rate was only 8% on the 6th day of paraquat ingestion in Control Group mice. Protective effect of MCI-186 was most evident and the survival rate was 42% on the 6th day and 38% on the 14th day of paraquat ingestion, respectively, when mice were treated immediately. A delay of 30 min in treatment resulted in an abrupt reduction of the survival rate. These results suggested that MCI-186 used in acute phase of paraquat intoxication might serve as a clinically available antidote for attenuating paraquat toxicity.

Animals↗

PubMed2003

ML-7 inhibits exocytosis of superoxide-producing intracellular compartments in human neutrophils stimulated with phorbol myristate acetate in a myosin light chain kinase-independent manner.

ML-7, (5-iodonaphthalene-1-sulfonyl) homopiperazine, is commonly employed as a myosin light chain kinase (MLCK) inhibitor. In the present study, we demonstrated that ML-7 affects the superoxide (O(2)(-))-producing system of human neutrophils in an MLCK-independent manner. Human neutrophils were stimulated with phorbol myristate acetate (PMA), which does not activate MLCK. ML-7 inhibited extracellular release, but not intracellular production of O(2)(-) in the stimulated cells. Fluorescence microscopy revealed the generation of O(2)(-) at intracellular compartments in the stimulated cells exposed to ML-7. At the electron microscopic level, the reaction product of NADPH oxidase activity was found in intracellular compartments. ML-7 strongly inhibited the association of the oxidant-producing intracellular compartments with the plasma membrane. Furthermore, the upregulation of alkaline phosphatase activity, a marker enzyme of the oxidant-producing intracellular compartments, was also inhibited by ML-7. These findings indicate that ML-7 inhibits the fusion of the oxidant-producing intracellular compartments to the plasma membrane resulting in the inhibition of the extracellular release of O(2)(-) in PMA-stimulated human neutrophils in an MLCK-independent manner.

Alkaline Phosphatase↗