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Biomedical subjects

H Maeda

Publications and source records attributed to H Maeda.

At least 559 records · Page 31Linked to original sources
PubMed1995

Superoxide radical generation from heterocyclic amines.

Highly purified cytochrome P-450 reductase (also called cytochrome C reductase; EC 1.6.2.4.) and NADPH were found to generate superoxide radical (O2.-) from 11 different heterocyclic amines (HCAs) as identified by electron spin resonance spectroscopy (ESR) using the spin trapping method with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). The signal intensity of DMPO-OOH(-O2.-) (i.e., the DMPO spin adduct of O2.-) was strongest for 2-amino-3,4-dimethylimidazo[4,5-f]-quinoline (MeIQ). O2.- generation with HCAs was decreased in the following order: 2-amino-3,8-dimethylimidazo[4,5-f]-quinoxaline (MeIQx) = 2-amino-3-methylimidazo[4,5-fl-quinoline (IQ) > 2-amino-3,4,8-trimethylimidazo[4,5-f]-quinoxaline (diMeIQx) > or = other HCAs; O2.- generation was lowest with 2-amino-3-methyl-9H-pyrido[2,3-b]indole-CH3COOH (MeA alpha C). By using Lineweaver-Burk plots, Km values of cytochrome P-450 reductase for mitomycin C, IQ, and MeIQ were determined to be 1.60 x 10(-6)M, 1.97 x 10(-5)M, and 2.83 x 10(-6) M, respectively. The N-hydroxyl derivative of 3-amino-1-methyl-5H-pyrido[4,3-b]-indole-HCI-CH3COOH (Trp-P-2), which is considered to be a key intermediate in the reaction of Trp-P-2 with cytochrome P-450 systems, yielded very little generation of O2.-. Because of the known presence of cytochrome P-450 reductase in the cell at significant amount, the present findings are an important implication for carcinogenesis and tumor promotion due to the known effect of oxygen radicals on promotion/progression, cell kill and proliferation.

Amines↗
PubMed1995

[Inhibitory effect of low molecular weight heparin on the bronchoconstriction in ovalbumin-sensitized guinea pigs after antigen exposure].

To elucidate the effect of low molecular weight heparin (LMWH) on the bronchoconstriction, we examined the serial changes of the resistance of respiratory system (Rrs) in ovalbumin (OA)-sensitized guinea pigs after antigen exposure. After sensitization of guinea pigs with repeated OA inhalation, Rrs was measured at immediate asthmatic response (IAR) and late asthmatic response (LAR) with or without LMWH inhalation. Alteration in the number of inflammatory cells of the lung by LMWH inhalation was examined in the broncholaveolar lavage fluid (BALF) and in the histological sections of airway walls. Peak Rrs at 1 min up to 9 min, except 8 min, after antigen exposure significantly decreased by the pretreatment with LMWH inhalation as compared with saline inhalation. Peak Rrs at LAR (after 4 hours up to 24 hours, except 6 hours) also showed a significant decrease in the pretreatment with LMWH inhalation. Pretreatment of LMWH exhibited a decrease of eosinophil percentage in BALF (5.5 +/- 1.2% from 8.2 +/- 0.4% in saline inhalation) and a decrease of infiltrated eosinophil count in airway walls (71.0 +/- 7.3 from 155 +/- 15.8 in saline inhalation). These data show LMWH might play an important role as an inhibitory factor to bronchial asthma.

Administration, Inhalation↗
PubMed1994

Generation of free radicals from neocarzinostatin mediated by NADPH/cytochrome P-450 reductase via activation of enediyne chromophore.

Neocarzinostatin (NCS) is one of the most potent antitumor agents. It contains a chromophore of a unique enediyne structure as its prosthetic group. Here, we report the generation of free radicals from NCS by the NADPH/cytochrome (cyt) P-450 reductase system. Free radical species, which were generated in the reaction mixture of NCS/NADPH/cyt P-450 reductase, were identified by using electron spin resonance spin trapping with 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The spin adducts of superoxide and hydroxyl radical (DMPO-OOH and DMPO-OH, respectively) were generated in the reaction of NCS with the NADPH/cyt P-450 reductase system. From kinetic analyses of DMPO-OOH generation as a function of the concentration of NCS, the Vmax/Km value of the reaction was 0.4 x 10(6) M-1min-1. In addition, we identified thiyl radical generation in this system in the presence of glutathione. These results indicate that NCS is a potent generator of free radicals in cells where cyt P-450 reductase is available. Moreover, it seems that free radicals, generated by enzymatic activation of NCS, are involved in cytotoxicity of NCS as well as in DNA damage.

Animals↗
PubMed1994

Novel cell-surface Ag expressed on rat osteoclasts regulating the function of the calcitonin receptor.

Osteoclasts are known to be hematopoietic in origin. However, the detailed mechanisms of their differentiation and activation are not known. Cell-surface molecules preferentially expressed on cells of the osteoclast lineage may play some important roles in these processes. We prepared a mAb that recognizes a unique cell-surface membrane protein specifically expressed on rat osteoclasts. Expression of this Ag, designated as Kat1 Ag, was markedly stimulated by a factor secreted by the osteoblastic cell line ROS 17/2.8. Binding studies of 125I-labeled calcitonin (CT) showed that the Ag was not the CT receptor (CTR). However, interestingly, studies of the biologic activity of this mAb that recognizes Kat1-antigen (mAb Kat1) revealed possible regulatory functions of this Ag in osteoclasts. Firstly, mAb Kat1 significantly elevated the binding affinity of the CTR expressed on osteoclast-like cells without altering the number of receptors. Secondly, CT-sensitivity of the osteoclast progenitor cells in the system of osteoclast differentiation showed marked augmentation on treatment of these cells with this mAb. Even a very low concentration of CT (0.1 ng/ml) significantly inhibited osteoclast differentiation in the presence of mAb Kat1, whereas a higher concentration of CT (10 ng/ml) was required to inhibit their differentiation in the absence of this mAb. Thirdly, mAb Kat1 inhibited dentin-resorbing activity of osteoclast-like cells. Furthermore, the inhibitory effects of CT on osteoclast-mediated dentin resorption was augmented by the presence of this mAb. These observations strongly suggest that Kat1-antigen is a unique cell-surface protein regulating the affinity of the CTR expressed on osteoclasts and also the bone-resorbing function of these cells.

Animals↗
PubMed1994

[Clinical trials of TAE using micro-coil coated with n-butyl 2-cyanoacrylate and lipiodol].

Clinical trials of TAE using microcoils (Target, USA) coated with n-butyl 2-cyanoacrylate and lipiodol were performed. The procedures were as follows. First, a small amount of lipiodol was injected into a Tracker 18 catheter. Secondly, a microcoil coated with n-butyl 2-cyanoacrylate and lipiodol was inserted into the microcatheter. Thirdly, a small amount of lipiodol was again administered into the catheter just behind the coil. Finally, the coil was pushed safely out from the catheter with a special guidewire. With this method, excellent occlusion of small arteries was obtained. There were no complications.

Embolization, Therapeutic↗
PubMed1994

Vasodilator effect of carboxy-2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl in the coronary circulation: in vivo and in vitro studies.

2-Phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) derivatives, new radical forms of nitric oxide (NO) antagonists, are reported to react with NO and generate NO2 and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl (PTI) derivatives. We found that carboxy-PTI, a water-soluble derivative of PTI, showed a potent vasodilator effect in the canine coronary artery system. In anesthetized dogs, intracoronary infusion of carboxy-PTI significantly increased the coronary flow in a dose-dependent manner without altering systemic hemodynamic variables. This coronary flow increasing effect of carboxy-PTI was not influenced by pretreatment with either NG-nitro-L-arginine methyl ester or 8-phenyltheophylline or autonomic blockade. However, the flow increasing effect of carboxy-PTI was abolished by reducing carboxy-PTI with ascorbic acid to a non-radical form of carboxy-PTI, indicating that carboxy-PTI shows its effect only in a radical form. In isolated canine coronary arterial rings, carboxy-PTI caused endothelium-independent relaxation. This relaxation response was significantly attenuated by pretreatment with methylene blue, an inhibitor of soluble guanylate cyclase. Thus, carboxy-PTI has an endothelium-independent coronary vasodilator effect in both large conduit arteries and small resistance vessels. The results of the in vitro experiment suggested that the activation of soluble guanylate cyclase of the vascular smooth muscle cell may be involved, at least in part, in the vasodilator mechanism of carboxy-PTI in large conduit arteries.

Animals↗
PubMed1994

Activation of blood clotting factors by microbial proteinases.

There are very few reports on the involvement of bacterial proteinases on the blood clotting system using both human plasma and purified clotting factors. We studied whether microbial proteinases from the opportunistic pathogens Candida albicans, Pseudomonas aeruginosa and Serratia marcescens activate the blood clotting cascade by using normal human plasma, human plasmas deficient in clotting factor XII or X, and also by using purified clotting factors XII, X and prothrombin. All proteinases tested activated either clotting factor XII or prothrombin in vitro, thus resulting in generation of thrombin. Clotting factor X was converted to the active form (Xa) by both Candida and Pseudomonas proteinases, but not by Serratia proteinase. These results suggest that peripheral and systemic blood circulation may be impaired by activation of the blood clotting cascade by microbial infections, especially in septic patients, which would enhance disseminated intravascular coagulation and multi-organ failure.

Amino Acid Sequence↗
PubMed1994

Therapeutic effects of imidazolineoxyl N-oxide against endotoxin shock through its direct nitric oxide-scavenging activity.

We recently found a new class of nitric oxide (NO) antidote, i.e., 2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide derivatives (PTIOs). It has a potent inhibitory action against endothelium-derived relaxing factor. Here, we report the effect of a water-soluble carboxy derivative of PTIO (carboxy-PTIO) on endotoxin shock. Endotoxin [lipopolysaccharide (LPS)] (10 mg/kg) was injected into Wistar rats, and the mean arterial blood pressure (MABP), heart rate and urinary parameters were continuously measured. The MABP and urine volume gradually decreased during 1 hr after LPS injection, and within 4 hr, both values decreased to 50-70%. When carboxy-PTIO at 0.056-1.70 mg/kg/min was infused for 1 hr beginning 90 min after the LPS injection, the hypotension, renal dysfunction and survival rate were much improved and the state of shock was avoided. Carboxy-PTIO administered to normal rats did not affect each parameter. Measurement of urinary output of carboxy-PTIO and carboxy-2-phenyl-4,4,5,5-tetramethylimidazole-1-oxyl (carboxy-PTI), which is a reaction product of carboxy-PTIO and NO, showed that conversion of carboxy-PTIO to carboxy-PTI was augmented by LPS treatment due to the increased production of NO, and that the enhanced conversion (PTIO-->PTI) was significantly inhibited by administration of N omega-monomethyl-L-arginine. This indicates that carboxy-PTIO exhibits a potent therapeutic value in endotoxin shock through the direct scavenging action against NO.

Animals↗
PubMed1994

[Three-dimensional CT imaging of pulmonary nodules using helical scan CT].

To evaluate the usefulness of three-dimensional (3D) imaging of pulmonary nodules from helical scan CT images, 3D reconstructions were performed in 23 patients, using a CEMAX VIPstation. These cases included 15 lung cancers, six metastatic lung cancers, an aspergilloma and a tuberculoma. The equipment used was a Toshiba CT system, the X force. Helical scan CT data were acquired using up to 20 continuous 1.5 sec rotations with an X-ray beam width of 5 mm and a couchtop movement speed of 5 mm/1.5 sec, and during a single breath-hold. Axial images were reconstructed at a section interval of 2 mm. Helical scan CT permits axial images to be reconstructed at any desired position within the scanned area, and provides images without interslice gaps caused by respiratory movement. Therefore, high-quality 3D images can be obtained from these data. Concerning the optimum threshold range of CT number of 3D reconstruction, we clarified the lower and upper limits (lower/upper), as follows: 1) Solid pulmonary nodule: (-700-(-)400/-100 HU) 2) Tumor invaded to pleura or chest wall: (-700-(-)400/-200 HU) 3) Pulmonary nodule with cavity: (-700-(-)400/50 HU) 4) Small pulmonary nodule (< 10 mm): (-750-(-)600/-100 HU) In all cases, it was possible not only to demonstrate abnormal findings three-dimensionally, but also to grasp anatomical relationships among the pulmonary nodule, bronchi, vessels and chest wall. In conclusion, it was considered that 3D CT imaging provided additional anatomical information and was very useful.

Adenocarcinoma↗
PubMed1994

Heat shock protein 60 (GroEL) from Porphyromonas gingivalis: molecular cloning and sequence analysis of its gene and purification of the recombinant protein.

Porphyromonas gingivalis is associated with human periodontal disease. We cloned and sequenced the gene for heat shock protein 60 (GroEL, HSP60) from P. gingivalis FDC381. The identified clone carried a 2.6 kb DNA fragment which contained two open reading frames (ORFs) encoding a 9.6- and a 58.4-kDa protein. The translated amino acid sequence of these ORFs showed a high degree of homology with known sequences for GroES and GroEL from several bacterial species and humans. Escherichia coli carrying this clone expressed a 65-kDa protein which was recognized by anti-Mycobacterium leprae HSP60 monoclonal antibody. We purified the 65-kDa protein by DEAE-sepharose chromatography and hydroxyapatite chromatography. This protein was immunogenic and was recognized by sera from a number of patients with periodontal disease. This immunological reactivity and the existence of molecular mimicry between the P. gingivalis GroEL and other HSP homologs may indicate an important role for this molecule in periodontal lesion.

Amino Acid Sequence↗
PubMed1994

Targeted disruption of the CD3 eta locus causes high lethality in mice: modulation of Oct-1 transcription on the opposite strand.

CD3 zeta and eta chains are components of the T cell antigen receptor (TCR) complex and are transcribed from a common gene by alternative splicing. TCR complexes containing the zeta eta dimer have been thought to mediate different functions than complexes containing the zeta 2 dimer. To analyze the role of eta in the development and function of T cells, we generated eta-deficient mice without affecting zeta by gene targeting in embryonic stem cells. Homozygous mutant embryos developed normally. Unexpectedly, however, these mice exhibited high mortality soon after birth for unknown reason(s). Analysis of surviving homozygous animals revealed that the development and function of T cells were normal in the absence of the eta chain. Recently, the zeta/eta locus was reported to encode a transcription factor, Oct-1, on the opposite DNA strand. Our targeting strategy resulted in modulation of Oct-1 transcription--reduction of the authentic Oct-1 mRNA and induction of aberrant transcripts. Although differences in tissue distribution and DNA binding capacity of Oct-1 between wild-type and eta-deficient mice were not evident from in situ hybridization and gel shift analysis, the high mortality in the eta-deficient strain may well be due to the disturbance of Oct-1 transcription by the mutation in the zeta/eta locus. Such possible complexities have to be taken into account in the interpretation of gene targeting experiments.

Animals↗
PubMed1994

Multiple functions of nitric oxide in pathophysiology and microbiology: analysis by a new nitric oxide scavenger.

A wide range of biological functions of nitric oxide (NO) was analyzed using a newly discovered nitric oxide scavenger, 2-phenyl-4,4,5,5-tetramethylimidazolineoxyl-1-oxyl-3-oxide (PTIO) or its water-soluble derivative carboxy-PTIO. The chemistry is very simple in that NO was oxidized by PTIO, yielding one mole each of NO2 and 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl. Based on the potent NO-scavenging activity of PTIO derivatives, the diverse functions of NO under physiological states as well as various pathological conditions such as endotoxin shock and viral diseases are now explicated. It was found that PTIO and carboxy-PTIO showed significant inhibitory activity against a series of biological actions of NO: (1) endothelium-dependent vascular relaxation in an ex vivo system, (2) pathogenicity of NO produced excessively in endotoxin shock in rats and in influenza virus pneumonitis in mice, and (3) enhanced vascular permeability in solid tumors mediated by NO. PTIO directly extinguishes NO generated by NO synthase (NOS) without affecting NOS activity, which is a clear contrast to NOS inhibitors. Therefore, characterization of this unique mode of action of PTIO appears to be helpful not only in understanding of the pathophysiological role of NO but also in the treatment of various diseases caused by excessive production of NO.

Animals↗
PubMed1994

The presence of giant granules in the juxtaglomerular cells of beige rats may affect plasma renin activity and blood pressure.

Chediak-Higashi syndrome (CHS) is an autosomal recessive disorder, characterized histopathologically by giant granules in various cells. Since little is known about the juxtaglomerular (JG) cells of CHS, the present study was undertaken as a morphological investigation of the JG cell of Beige rats, which were found to be a new animal model of CHS. In addition, we measured the blood pressure and plasma renin activity. The blood pressure of Beige rats is similar to that of DA rats, the mother strain of Beige rats. However, the plasma renin activity of Beige rats increases with age, whereas that of DA rats decreases. Morphologically, JG cells of Beige rats gave no evidence of hyperplasia and hypertrophy. The most conspicuous change was a small number of giant JG granules. Ultrastructurally, JG granules of Beige rats were large, irregular, and varied in size at 2 months of age, but no age-dependent changes were detected. These results suggested that giant JG granule formation slightly increases renin release with age, but does not affect blood pressure.

Animals↗
PubMed1994

Therapeutic intervention with chicken egg white ovomacroglobulin and a new quinolone on experimental Pseudomonas keratitis.

BACKGROUND: Chicken egg white ovomacroglobulin (ovoM) is a potent protease inhibitor with broad-spectrum activity against various proteases. The combined effects of ovoM and the new quinolone, ofloxacin (OFLX) on experimental Pseudomonas aeruginosa keratitis were investigated. METHODS: The in vitro inhibitory effects of ovoM on protease activity in culture fluid of clinically isolated P. aeruginosa and on activity of human neutrophil elastase and cathepsin G were assayed using azo-casein as substrate. Albino rabbits received intrastromal injection of the isolated Pseudomonas strain (1 x 10(5) colony-forming units). At 16 h after inoculation, three treatment groups--0.1% ovoM alone, 0.3% OFLX alone, and a combination of both--and a non-treatment control group were tested. RESULTS: Protease activity in the culture solution and human neutrophil elastase was inhibited by ovoM, whereas cathepsin G was not inhibited effectively. In vivo additive therapeutic effects of ovoM and OFLX were observed at 96 h (P < 0.05 compared with OFLX alone). CONCLUSION: The results indicate that inhibition of proteolytic activity with ovoM is useful in preventing stromal degradation in P. aeruginosa keratitis.

Animals↗
PubMed1994

Localization of osteopontin in resorption lacunae formed by osteoclast-like cells: a study by a novel monoclonal antibody which recognizes rat osteopontin.

The characteristics of a monoclonal antibody produced against osteoclast-like multinucleated cells (MNCs) formed in rat bone marrow cultures were examined immunohistochemically and biochemically. The in vitro immunization was performed using as immunogen the MNCs from rat bone marrow cell culture, which revealed many characteristics of osteoclasts. After screening and cloning of hybridomas, the monoclonal antibody HOK 1 was obtained. This antibody reacted weakly with stromal cells and intensely with both MNCs and their putative migratory traces on culture dishes. Immunofluorescent examination of paraffin sections revealed intense reactivity on the epithelium of the choroid plexus, the ileum and the proximal-convoluted tubules of the kidney, and also on bone cells such as osteocytes, osteoblasts, and osteoclasts. Western blotting using purified rat osteopontin verified that the antigen recognized by HOK 1 was osteopontin. Positive HOK 1 immunoreactivity was further observed in the resorption lacunae formed by a culture of MNCs on human tooth slices and on the surface of osteoclasts. The present data suggested that osteopontin is preferentially present on the resorption lacunae in resorbing calcified matrices and that osteoclasts under a specific state might trap this protein on their cell surface.

Animals↗
PubMed1994

Combined antitumor effects of TNF and G-CSF on a human medulloblastoma xenograft line.

The antitumor effects of TNF and G-CSF on a xenograft line of human medulloblastoma were examined. (Method):1) A human medulloblastoma xenograft line was transplanted into nude mice. Tumor bearing nude mice were divided into the following eight groups: untreated controls (C); those receiving a subcutaneous injection of G-CSF for one week (G1); for four weeks (G2); those receiving an intratumoral injection of TNF for four weeks (Tit); an intravenous injection of TNF (Tiv); those receiving a combination of G1 and Tit (G1 + Tit); a combination of G2 and Tit (G2 + Tit); and a combination of G2 and Tiv (T2 + Tiv). The relative tumor weight in each group was calculated and any antitumor effects were examined by calculating a tumor growth inhibition ratio. 2) Tumor bearing nude mice were divided into the following two groups: those receiving a subcutaneous injection of G-CSF and an intravenous injection of TNF (G+T); and only an intravenous injection of TNF (T). We evaluated the pathological findings from the tumors at 0 h, 0.5 h, 1 h, 3 h, 6 h, 12 h, 24 h and 48 h after the TNF injection. Routine H.E. staining and immunostaining using antigranulocyte and antimacrophage antibodies were performed. (Results): 1) The tumor growth inhibition ratio was 0.112, 0.190, 0.287, 0.451, 0.347, 0.635, and 0.622 at G1, G2, Tit, Tiv, G1 + Tit, G2 + Tit, G2 + Tiv group. A combined antitumor effect was clearly seen in the G2 + Tit and the G2 + Tiv groups. 2) The tumor was fragmented by the infiltration of many inflammatory cells 24 hours after TNF injection. Many more macrophages were observed in the tumors of G+T mice than in the T mice. Granulocytes were observed only in the tumors of the G+T mice.

Animals↗