Biomedical subjects

M Kuwabara

Publications and source records attributed to M Kuwabara.

At least 55 records · Page 3Linked to original sources

PubMed2000

[Results of antimicrobial susceptibilities of strains clinically isolated at 8 institutions in Hiroshima City to major oral antimicrobial drugs, mainly new quinolone drugs. Hiroshima Levofloxacin Susceptibility Surveillance Group].

To evaluate the resistance for major oral antimicrobial agents, mainly new quinolones, we carried out a drug susceptibility surveillance of 3,050 strains of 11 microbial species clinically isolated at 8 institutions such as general hospitals and examination centers in Hiroshima city. 10 antimicrobial agents were used: 3 new quinolone drugs, 5 beta-lactam drugs, minocycline and clarithromycin. Among Gram-positive bacteria, methicillin resistant Staphylococcus aureus (MRSA) and Enterococcus faecalis showed low susceptibility to the new quinolone drugs, while methicillin susceptible Staphylococcus aureus (MSSA) and Streptococcus pneumoniae were highly sensitive to these drugs. Among Gram-negative bacteria, Pseudomonas aeruginosa showed high resistance for the new quinolone drugs, but enteric bacteria and Haemophilus influenzae did not show marked resistance, maintaining almost good sensitivity to these drugs. To reduce the appearance of resistant bacteria, appropriate antimicrobial agents should be selected. Drug susceptibility surveillance in the community will be also important in the future.

4-Quinolones↗

PubMed1999

Cloning, expression, and chromosomal mapping of a human ganglioside sialidase.

Here we report the cDNA sequence of a human ganglioside sialidase. The cDNA was isolated from a human brain cDNA library by screening with a 240 bp probe generated by polymerase chain reaction using primers based on the sequences of rat cytosolic and bovine membrane sialidases which we previously cloned. The 3.0 kb cDNA encodes an open reading frame of 436 amino acids containing a putative transmenbrane domain and an Arg-Ile-Pro and three Asp-box sequences characteristic of sialidases and showing overall 83% and 39% identities to the bovine and rat enzymes, respectively. Northern blot analysis revealed high expression in skeletal muscle and testis, but low level in kidney, placenta, lung, and digestive organs. Transient expression of the cDNA in COS-1 cells resulted in a 130-fold increase in sialidase activity compared to the control level, and the activity was found to be almost specific for gangliosides. Fluorescent in situ hybridization allowed the human sialidase gene localized to chromosome 11 at q 13.5.

Amino Acid Sequence↗

PubMed1999

Inflammatory cell-mediated tumour progression and minisatellite mutation correlate with the decrease of antioxidative enzymes in murine fibrosarcoma cells.

We isolated six clones of weakly tumorigenic fibrosarcoma (QR) from the tumorigenic clone BMT-11 cl-9. The QR clones were unable to grow in normal C57BL/6 mice when injected s.c. (1x10(5) cells). However, they formed aggressive tumours upon co-implantation with a 'foreign body', i.e. a gelatin sponge, and the rate of tumour take ranged from 8% to 58% among QR clones. The enhanced tumorigenicity was due to host cell-mediated reaction to the gelatin sponge (inflammation). Immunoblot analysis and enzyme activity assay revealed a significant inverse correlation between the frequencies of tumour formation by QR clones and the levels of manganese superoxide dismutase (Mn-SOD, P<0.005) and glutathione peroxidase (GPchi, P<0.01) in the respective tumour clones. Electron spin resonance (ESR) revealed that superoxide-scavenging ability of cell lysates of the QR clone with high level of Mn-SOD was significantly higher than that with low level of the antioxidative enzyme in the presence of potassium cyanide, an inhibitor for copper-zinc superoxide dismutase (CuZn-SOD) (P<0.001). Minisatellite mutation (MSM) induced by the inflammatory cells in tumour cells were investigated by DNA fingerprint analysis after QR clones had been co-cultured with gelatin-sponge-reactive cells. The MSM rate was significantly higher in the subclones with low levels of Mn-SOD and GPchi (P<0.05) than in the subclones with high levels of both enzymes. The MSM of the subclones with low levels of both enzymes was inhibited in the presence of mannitol, a hydroxyl radical scavenger. The content of 8-hydroxydeoxyguanosine (8-OHdG) by which the cellular DNA damage caused by active oxygen species can be assessed was significantly low in the tumours arising from the QR clone with high levels of Mn-SOD and GPchi even if the clone had been co-implanted with gelatin sponge, compared with the arising tumour from the QR clone with low levels of those antioxidative enzymes (P<0.001). In contrast, CuZn-SOD and catalase levels in the six QR clones did not have any correlation with tumour progression parameters. These results suggest that tumour progression is accelerated by inflammation-induced active oxygen species particularly accompanied with declined levels of intracellular antioxidative enzymes in tumour cells.

Animals↗

PubMed1999

Effects of intracellular calcium chelator BAPTA-AM on radiation-induced apoptosis regulated by activation of SAPK/JNK and caspase-3 in MOLT-4 cells.

PURPOSE: To examine the roles ofintracellular calcium in radiation-induced apoptosis of MOLT-4 cells, the effects of intracellular calcium chelator BAPTA-AM on the induction of apoptosis and the activation of apoptosis-relating enzymes SAPK/JNK and caspase-3 were studied. MATERIALS AND METHODS: MOLT-4 cells pretreated with 5 microM BAPTA-AM were exposed to X-rays. DNA fragmentation, the expression of phosphorylated SAPK/JNK and the activation of caspase-3 and calcium concentration were measured by agarose gel electrophoresis, Western blotting and spectrofluorometry. RESULTS: Time-dependent ladder-like DNA fragmentation was observed at 4h, 5 h and 6 h after exposure to 15 Gy of X-rays. This fragmentation was significantly attenuated by pretreatment with BAPTA-AM up to 5 h after irradiation, but the attenuation due to BAPTA-AM was no longer detectable at 6 h. Activation of SAPK/JNK and caspase-3 was observed at 1 and 4 h after X-irradiation, respectively, and BAPTA-AM retarded the activation for 2 h. The pretreatment with BAPTA-AM was found to suppress the increase of calcium concentration for 6h after irradiation. CONCLUSION: These results revealed that chelation of calcium merely delayed the onset of the radiation-induced apoptosis regulated by the activation of SAPK/JNK and caspase-3, and calcium was not essential for the induction of apoptosis in X-irradiated MOLT-4 cells.

Apoptosis↗

PubMed1999

Attenuation of caspase-3-dependent apoptosis by Trolox post-treatment of X-irradiated MOLT-4 cells.

PURPOSE: The relationship between post-irradiation treatment with Trolox, an antioxidant that inhibits lipid peroxidation, and X-ray-induced apoptosis, with regard to signal transduction pathways, was examined in MOLT-4, a human leukaemia cell line. MATERIALS AND METHODS: In MOLT-4 cells treated with Trolox after X-irradiation, viability, DNA fragmentation, expression of p53, BCL-2, BAX, active SAPK/JNK, active caspase-3 and the cleavage of PARP were measured by the trypan blue exclusion test, agarose gel electrophoresis and Western blotting. RESULTS: Stained cells and ladder-like DNA cleavage were observed after X-irradiation. Cell death and DNA fragmentation were significantly inhibited by the post-irradiation treatment with Trolox. The expression of p53 and active SAPK/JNK was increased after X-irradiation, and fragments of PARP and the activated fragment of caspase-3 were produced. Post-irradiation treatment with Trolox attenuated the X-irradiation-induced expression, fragmentation or activation of these apoptosis-related biomolecules. The expression of BCL-2 and BAX, which would occur downstream from p53, was not changed by irradiation and Trolox treatment. Furthermore, cell death was associated with caspase-3 because the ladder-like DNA cleavage was completely inhibited by Ac-DEVD-CHO but not Ac-YVAD-CHO, TLCK and PMSF. CONCLUSION: Post-irradiation events such as membrane damage induce caspase-3-dependent apoptosis, which might be mediated by the activation of SAPK/JNK and be independent of p53.

Antioxidants↗

PubMed1999

Hydroxyl radical generation and lipid peroxidation in C2C12 myotube treated with iodoacetate and cyanide.

To mimic exercise-induced events such as energetic impairment, free radical generation, and lipid peroxidation in vitro, mouse-derived C2C12 myotubes were submitted to the inhibition of glycolytic and/or oxidative metabolism with 1 mM iodoacetate (IAA) and/or 2 mM sodium cyanide (CN), respectively, under 5% CO2/95% air up to 180 min. Electron spin resonance (ESR) analysis with a spin-trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) revealed time-course increases in spin adducts from hydroxyl radical (DMPO-OH) and carbon-centered radical (DMPO-R) in the supernatant of C2C12 myotubes treated with the combination of IAA + CN. In this condition, malondialdehyde (MDA) and lactate dehydrogenase (LDH) were released into the supernatant. By the addition of iron-chelating 1 mM deferoxamine to the C2C12 preparation with IAA + CN, both ESR signals of DMPO-OH and DMPO-R were completely abolished, and the release of MDA and LDH were significantly reduced, while cyanide-resistant manganese superoxide dismutase had negligible effects on these parameters. Hence, a part of the injury of C2C12 myotube under IAA + CN was considered to result from the lipid peroxidation, which was induced by hydroxyl radical generated from iron-catalyzed systems such as the Fenton-type reaction. This in vitro model would be a helpful tool for investigating the free radical-related muscle injury.

Animals↗

PubMed1999

Suppression of late asthmatic response by low-dose oral administration of interferon-beta in the guinea pig model of asthma.

We investigated the anti-asthmatic effects of low-dose oral and subcutaneous administration of interferon-beta (IFN-beta) on an ovalbumin (OVA)-sensitized and challenged guinea pig model of asthma. Subcutaneous administration of IFN-beta suppressed the eosinophil infiltration by 14.2% of the control and the respiratory resistance (Rrs) by 58.2% at 2.0 MIU/kg. Oral administration of IFN-beta inhibited the late asthmatic response (LAR) by suppressing the increase of Rrs by 29% of the control at 1 IU/ml and the eosinophil infiltration into the trachea and lung by 34.6% at the optimum dosage of 10 IU/ml. Both subcutaneous and oral administration could not inhibit the early asthmatic response (EAR). Additionally we found 2',5'-oligoadenylate synthetase (2',5'-OAS) induction by low-dose oral administration (LDOA) of IFN-beta to the same extent as by subcutaneous administration in whole blood in vivo. These data suggest that LDOA of IFN-beta would have some clinical benefit for patients with asthma.

2',5'-Oligoadenylate Synthetase↗

PubMed1999

Hydrogen peroxide-induced activation of SAPK/JNK regulated by phosphatidylinositol 3-kinase in Chinese hamster V79 cells.

To clarify activation mechanisms of stress-activated protein kinase/C-Jun N-terminal kinase (SAPK/JNK) during oxidative stress, the roles of phosphatidylinositol 3-kinase (PI 3-kinase), concentration of intracellular calcium ([Ca2+]i), and cyclic AMP-dependent kinase (PKA) in hydrogen peroxide (H2O2)-induced SAPK/JNK activation were examined in Chinese hamster V79 cells. SAPK/JNK was dose-dependently activated after H2O2 treatment (from 10 microM to 1 mM), and a PI 3-kinase inhibitor (wortmaninn), intracellular calcium chelator (BAPTA-AM), and PKA activator (dibutyl cyclic AMP and forskolin) inhibited this activation. An increase in [Ca2+], was observed after treatment with H2O2. Immunoprecipitation revealed that a PI 3-kinase regulatory subunit, p85alpha, was associated with insulin receptor substance 1 (IRS-1) phosphorylated by H2O2 treatment. Furthermore, the formation of this complex of p85alpha and phospho-IRS-1 was abolished by the presence of BAPTA-AM but not forskolin. These results indicated that the PI 3-kinase activated through phosphorylation of IRS-1 upstream of SAPK/JNK after H2O2 treatment of V79 cells and that [Ca2+]i was a regulation factor for phosphorylation of IRS-1.

Androstadienes↗

PubMed1999

Elevation of intracellular calcium ions is essential for the H2O2-induced activation of SAPK/JNK but not for that of p38 and ERK in Chinese hamster V79 cells.

The mitogen-activated protein kinases (MAPK), including stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), p38, and extracellular signal-related kinase (ERK), are believed to be important biomolecules in cell proliferation, survival, and apoptosis induced by extracellular stimuli. In Chinese hamster V79 cells exposed to hydrogen peroxide (H2O2), we recently demonstrated that SAPK/JNK was activated by tyrosine kinase and intracellular Ca2+ ([Ca2+]i). In this study, we report that [Ca2+]i release from intracellular stores is important in the activation of SAPK/JNK but not p38 and ERK. H2O2-induced elevation of [Ca2+]i was observed in Ca2+-free medium. Pretreatment with thapsigargin, a Ca2+-ATPase inhibition of endoplasmic reticulum (ER), did not influence H2O2-induced elevation of [Ca2+]i in the absence of external Ca2+. An intracellular Ca2+ chelator (BAPTA-AM) inhibited H2O2-induced phosphorylation of SAPK/JNK, but an extracellular Ca2+ chelator (EDTA) or a Ca2+ entry blocker (NiCl2) did not. Activation of p38 and ERK in V79 cells exposed to H2O2 was observed in the presence of these inhibitors. These results suggest that [Ca2+]i release from intracellular stores such as mitochondria or nuclei but not ER, occurred after H2O2 treatment and Ca2+-dependent tyrosine kinase-induced activation of SAPK/JNK, although [Ca2+]i was unnecessary for the H2O2-induced activation of p38 and ERK.

Animals↗

PubMed1999

Malignant Brenner tumors of the ovary and tumor markers: case reports.

We investigated the tumor marker for malignant Brenner tumors, which had not been established because of the rarity and variable histological criteria. Representative areas of two cases of malignant Brenner tumor were investigated by means of the peroxidase-antiperoxidase method using monoclonal antibody to CA125 and CA72-4 antigen and the streptavidin-biotin immunoperoxidase complex method using monoclonal antibody to SCC antigen. Based on clinical course and immunohistochemical studies, serum CA125 and CA72-4 for Case 1 and SCC and CA72-4 for Case 2 were appropriate tumor markers for the establishment of the extent of tumor burden before treatment and to monitor the response to therapy. The discrepancy of the tumor markers of the two present cases is considered to be a reflection of the difference in the malignant component of these cases. However, serum CA72-4 was an appropriate tumor marker for both malignant Brenner tumors.

Aged↗

PubMed1999

Tea polyphenol intake and changes in serum pepsinogen levels.

Following a phase I study, a phase II study was conducted to evaluate the effects of two different doses of tea polyphenols on serum pepsinogen levels. Subjects were patients aged 40 to 69 years who had undergone gastroscopy between 1995 and 1997 at Aichi Cancer Center Hospital, and had been found to have no disease requiring medication. Those with pepsinogen I < 70 ng/ml and pepsinogen I/II ratio < 6 were included in this study. Capsules containing 100 mg of tea polyphenols were administered for 1 year: 1 capsule per day for 101 patients (42 males and 59 females), and 6 capsules (equivalent to 10 cups) per day for 83 patients (30 males and 53 females). The enrollment of the 1 capsule group preceded that of the 6 capsule group, in which re-participation was allowed. Blood samples were obtained 1 year after participation from 86 participants of the 1 capsule group and 77 participants (43 new participants and 34 re-participants) of the 6 capsule group. The compliance in polyphenol capsule intake ranged from 11.4 to 105.7% (87.6% on average) of the scheduled amount for the 1 capsule group and 3.2 to 112.3% (77.8% on average) for the 6 capsule group. No serious polyphenol-related adverse effects were reported. The difference in pepsinogen I between before and after 1 year intake of the polyphenol was 3.1 ng/ml for the 43 participants of the 6 capsule group, but 3.5 ng/ml for the 1 capsule group. The mean pepsinogen I/II ratio for the 43 participants increased from 2.37 by 0.08. This increase was not larger than that for the 1 capsule group (from 2.61 by 0.11). Among 34 participants in both interventions, no significant increase in pepsinogen I and I/II ratio for the 6 capsule intervention was observed. This result suggests that additional polyphenol intake for 1 year in Japanese does not improve pepsinogen levels, which are considered to reflect stomach atrophy, a high-risk condition for stomach cancer.

Adult↗

PubMed1999

MR imaging of hepatic injury in the LEC rat under a high magnetic field (7.05 T).

Visualization of copper-induced hepatitis (CuH) in LEC rats was performed by using an MRI apparatus equipped with a magnet producing a high magnetic field of 7.05 T. When three groups of LEC rats (6-16 [pre-hepatitis], 15-26 [acute hepatitis] and 40-77 [chronic hepatitis] weeks old) were examined by MRI under T2-weighted imaging conditions which are suitable for the diagnosis of human hepatitis, hypointense MR images of the livers were, as a whole, obtained in all groups, suggesting that these conditions were not adequate for imaging of CuH of LEC rats. The shortening of the T1 and T2 relaxation times of livers due to an excess amount of paramagnetic irons under the high magnetic field was responsible for the lowering of MR signal intensities of the livers, especially those of 15 to 26-week old rats showing acute hepatitis. However, theoretical calculation of the MR signal intensities using the T1 and T2 relaxation times of the livers indicated that their imaging might be possible under proton density-weighted conditions even with a high magnetic field. Experimental results showed that hepatic injury was visualized as hyperintense regions in the MR image of the liver in the acute-phase rat.

Animals↗

PubMed1999

Morphological observation of canine natural killer cells mediated cytotoxicity.

The cytotoxic effects of canine NK cells on CL-1 target cells were examined by scanning electron microscopy (SEM). NK cell mediated cytotoxicity on CL-1 target cells was detected by 51Cr release assay. SEM showed that a canine NK cell extended projections to the CL-1 target cell. Furthermore, the surface of CL-1 target cells changed a mesh-like structure. Therefore, the cytotoxic effects of canine NK cells on CL-1 target cells were morphologically demonstrated.

Animals↗

PubMed1999

Lipid peroxides and antioxidants in serum of neonatal calves.

OBJECTIVE: To examine the association between oxidative stress and antioxidants in neonatal calves after birth. SAMPLE POPULATION: Sera from 6 healthy Holstein-Friesian cows and 7 of their newborn calves were obtained at various intervals after birth. PROCEDURE: Lipid peroxides in serum of cows and their newborn calves were estimated by measuring concentrations of thiobarbituric acid-reactive substances (TBARS). The antioxidative activities of neonatal sera were evaluated by measuring their superoxide-scavenging activities, ferroxidase activities, and the concentration of bilirubin-associated albumin. RESULTS: Concentration of TBARS in neonatal sera within 1 day after birth was significantly higher than concentrations > or = 2 days after birth and concentrations in serum of the dams. In contrast, antioxidative activities of neonatal sera, evaluated on the basis of superoxide-scavenging activities, ferroxidase activities, and concentration of bilirubin-associated albumin 3 hours after birth, were significantly lower than antioxidative activities in sera of the dams. CONCLUSIONS: Susceptibility of calves to oxidative stress during the neonatal period may be explained by the immature defense system against superoxide radicals.

Animals↗

PubMed1999

[In vitro activities of 23 antimicrobial agents against 4,993 gram-positive and gram-negative bacterial strains isolated from multicenter of Japan during 1994--in vitro susceptibility surveillance.Levofloxacin-Surveillance Group].

In a surveillance study conducted during 1994 at 24 medical institutes from different geographical areas of Japan, the susceptibility of clinical isolates to twenty three comparative agents, such as ofloxacin, levofloxacin, ciprofloxacin, tosufloxacin, ampicillin, clavulanic acid/amoxicillin, oxacillin, piperacillin, cefaclor, cefotiam, cefdinir, cefclidin, ceftazidime, cefpirome, imipenem, aztreonam, vancomycin, minocycline, chloramphenicol, clarithromycin, sulfamethoxazole/trimethoprim, amikacin, and gentamicin, were tested by the standard broth micro-dilution method. A total of 4,993 isolates tested in this study included Streptococcus pneumoniae, methicillin susceptible Staphylococcus aureus (MSSA), methicillin resistant Staphylococcus aureus (MRSA), coagllase negative streptococci (CNS), Enterococcus faecalis, Enterococcus faecium, Enterobactericeae, Pseudomonas aeruginosa from patients with urinary tract infections or respiratory tract infections, and Haemophilus influenzae. For MSSA, S. pneumoniae, Enterobacteriaceae, and H. influenzae, more than 70% of the isolates was susceptible to fluoloquinolones. However, resistance occurred in more than 50% of MRSA and P. aeruginosa isolated from UTI. Fluoroquinolones were found to be effective against high level penicillin-resistant S. pneumoniae, the third generation cephem-resistant Enterobacteriaceae and ampicillin-resistant H. influenzae.

Anti-Bacterial Agents↗

PubMed1999

Effects of BAPTA-AM and forskolin on apoptosis and cytochrome c release in photosensitized Chinese hamster V79 cells.

The mechanism of caspase-3-dependent apoptosis induced by photodynamic therapy (PDT) of cultured Chinese hamster V79 cells with pheophorbide a (PPa) was investigated. The PPa-PDT induced rapid apoptosis within 30 min after irradiation of cells. This apoptosis was inhibited by the 1O2 quencher N3- and caspase-3 inhibitor acetyl-Asp-Glu-Val-Asp-aldehyde, suggesting that 1O2 activated caspase-3 and then caused apoptosis. The intracellular calcium [Ca2+]i chelator (acetoxymethyl)-1,2-bis(o-aminophenoxy)ethane N,N,N',N'-tetraacetic acid (BAPTA-AM) and the cyclic adenosine monophosphate (cAMP)-increasing agent forskolin also inhibited not only the PPa-PDT-induced activation of caspase-3 but also apoptosis in V79 cells. Furthermore, PPa-PDT-induced cytochrome c release from mitochondria was found to be inhibited by the treatment with BAPTA-AM but not forskolin. These results indicated that [Ca2+]i and cAMP independently serve as regulators for PPa-PDT-induced apoptosis in the upstream of caspase-3.

Animals↗

PubMed1999

Mediastinitis due to Gordona sputi after CABG.

Genus Gordona is included in mycolic acid containing bacteria. This genus infection is very rare and occurs classically in immuno-compromised patients. We report a patient who developed mediastinitis due to Gordona sputi after coronary artery bypass grafting (CABG) using left internal mammary artery. Immunocompromised factors were not noticed in this case but postoperative bleeding, the most important risk factor of mediastinitis, was found in his course. The treatment was antibiotic therapy, surgical soft tissue debridement and open irrigation with dilute povidone-iodine solution. However, infectious reaction continued and Gordona sputi repeated cultured from wound. Next procedure, debridement of sternal bone and omental transfer, was performed and skin was closed primarily. Inflammatory reaction was attenuated and the wound was healed Broad debridement and omental transfer were very effective for mediastinitis due to Gordona sputi after CABG.

Actinomycetales Infections↗

PubMed1999

[CA125].

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Adult↗