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Biomedical subjects

M Okabe

Publications and source records attributed to M Okabe.

At least 235 records · Page 13Linked to original sources
PubMed1994

Characteristics of antitumor activity of KW-2189, a novel water-soluble derivative of duocarmycin, against murine and human tumors.

Methyl(1S)-1-bromomethyl-7-methyl-5-[(4-methylpiperazinyl)-carb onyloxy]- 3-[(5,6,7-trimethoxy-2-indolyl)-carbonyl]-1,2-dihydro-3H-pyrolo[3, 2-e] indole-8-carboxylate hydrobromide (KW-2189), a novel derivative of duocarmycin B2, was selected for extensive evaluation based on its improved antitumor activity, water solubility, and stability in the culture medium, as compared with duocarmycin B2. Although the in vitro cell growth-inhibitory activity of KW-2189 was less potent than that of duocarmycin B2, it significantly inhibited the growth of five murine solid tumors including Colon 26 adenocarcinoma, Colon 38 adenocarcinoma, and B16 melanoma in vivo. KW-2189 was also effective against murine P388 leukemia and L1210 leukemia not only by local administration (i.p.-i.p. system), but also by systemic administration (i.p.-i.v. or i.v.-i.v. system). The most remarkable feature of KW-2189 was its efficacy against various human xenografts, which was observed in 14 tumors among 16 tested tumors including drug-insensitive tumors by single i.v. administration. Tumor regression was observed in mice bearing LC-6 lung, St-4 and St-40 stomach, Li-7 liver, PAN-2 pancreas, and MX-1 breast carcinomas. In many cases, the activities of KW-2189 were more than those of clinically active agents, mitomycin C, Adriamycin, cisplatin, and cyclophosphamide. Delayed lethal toxicity, which was reported in mice treated with CC-1065 whose structure was similar to KW-2189, was not observed in mice treated with KW-2189. KW-2189 inhibited DNA synthesis more significantly than RNA or protein synthesis, although DNA strand breaks were not observed. KW-2189 was activated by porcine liver esterase, mouse liver homogenate or Hep G2 homogenate, and DU-86-DNA adducts were detected in KW-2189-treated HeLa S3 cells, suggesting that KW-2189 was converted to DU-86 in the cells. These results indicate that KW-2189 is an interesting candidate for further development as a novel antitumor agent.

Animals↗
PubMed1994

6H-pyrazolo[4,5,1-de]acridin-6-ones as a novel class of antitumor agents. Synthesis and biological activity.

The 7-substituted 6H-pyrazolo[4,5,1-de]acridin-6-ones with (aminoalkyl)amino and/or (hydroxyalkyl)amino groups in the side chains were synthesized by bromination using N-bromosuccinimide and the subsequent reaction with amines from the 7-substituted 5-bromo-2-methyl-6H-pyrazolo-[4,5,1-de]acridin-6-one. The substitution reaction of the amines with alkyl bromide (the C2 position) and aryl bromide (the C5 position) was accomplished by choosing the proper reaction conditions. These compounds show DNA intercalating ability in ethidium fluorescence assay and antiproliferative activity against Hela S3 cells. Impressive antitumor activity in vivo against murine P388 leukemia and murine sarcoma 180 solid tumor in mice was demonstrated for the 7-hydroxy analogs. In addition, some of these showed excellent antitumor activity against adriamycin-resistant murine P388 leukemia (P388/ADM) in mice.

Aminoacridines↗
PubMed1994

n-hexane-induced synthesis of hepatic metallothionein is mediated by IL-6 in mouse.

The mechanism of metallothionein (MT) synthesis in the liver by n-hexane (HX) was examined. The increased synthesis of MT in the liver by HX was inhibited by dexamethasone pretreatment. Serum IL-6 was increased soon after HX injection, reaching a maximum at 8-16 hr, and then decreased, but neither IL-1 nor TNF was increased. The hepatic MT concentration reached a maximum later than did the serum IL-6 concentration, at 2 days after administration. When the MT synthesis induced by HX was inhibited by dexamethasone pretreatment, the concentration of IL-6 in the serum was suppressed to a very low level. Furthermore, the increase in concentration of hepatic MT and plasma fibrinogen was significantly decreased by the anti-mouse IL-6 monoclonal antibody. The concentration of hepatic MT was higher when the concentration of HX in the olive oil of the solution for injection was higher, even when the amount of HX administered was the same. It is suggested that the cytokine(s) is produced by the macrophage and fibroblast through injury and inflammation at the site of administration. These findings suggest that MT synthesis resulting from HX is induced indirectly through cytokine(s) production, especially IL-6.

Animals↗
PubMed1994

Enhancement of cephamycin C production using soybean oil as the sole carbon source.

Vegetable oils were investigated to evaluate their potential to act as the sole carbon source for production of cephamycin C in shake and jar-fermentor cultures. Soybean oil was the best carbon source for cephamycin C production. Bioautography and HPLC analyses showed that cephamycin C was exclusively produced even when soybean oil was used as the sole carbon source. The optimal pH and initial concentration of soybean oil was 7.5 and 7 g/l, respectively. Both pH and the pH-control agent affected cephamycin C production, and among phosphoric acid, acetic acid and sulfuric acid, phosphoric acid was associated with the best production. Soybean oil was slowly consumed after the soluble nitrogen source was consumed. When the initial soybean oil concentration was 7 g/l, cephamycin C production was maximal, 2.0 g/l, which was twice as high as that from starch. The product yield from soybean oil was 4.7 times higher than that from starch. These results show that vegetable oils, which are cheaper than other carbon sources, could be used as the sole carbon source in the production of antibiotics.

Biotechnology↗
PubMed1994

Effect of UCN-01, a selective inhibitor of protein kinase C, on the cell-cycle distribution of human epidermoid carcinoma, A431 cells.

UCN-01 (7-hydroxy-staurosporine), a selective inhibitor of protein kinase C (PKC), was shown to exhibit antitumor activity in murine and human tumor cell lines in vitro and in vivo. On the other hand, staurosporine, a non-selective protein kinase inhibitor, was not shown to exert antitumor activity in vivo despite its potent antiproliferative activity in vitro. To compare the modes of action of UCN-01 and staurosporine in vitro, the effects of both drugs on the cell cycle progression of human epidermoid carcinoma A431 cells were examined by flow cytometry using propidium iodide (PI) staining. At 50% growth inhibitory concentrations, both UCN-01 and staurosporine induced G1 phase accumulation in the cell cycle. At 80% growth inhibitory concentrations, UCN-01 also induced preferential G1 phase accumulation, but staurosporine mostly induced G2M phase accumulation. Staurosporine also induced higher DNA ploidy when the cells were exposed to the drug for more than one generation time of A431 cells. An analysis of cell kinetics by 5-bromo-2-deoxyuridine incorporation versus DNA content confirmed that the G1 phase block by UCN-01 and the G1 and G2M phase block by staurosporine at the respective doses, as was the case for PI staining. Additionally, DNA synthesis of the cells, which was determined by the uptake of 3H-TdR, was not suppressed at least 8 h after the treatment with UCN-01. These results suggested that UCN-01 could affect the G1 phase of cell cycle in A431 cells in quite different manners from staurosporine. The G1 phase block induced by UCN-01 might be important for the growth inhibitory activity of UCN-01 against A431 cells in vitro and in vivo.

Alkaloids↗
PubMed1994

Chronic myeloid leukemia presenting ALL-type BCR/ABL transcript.

We investigated the breakpoints of the bcr gene in 46 Ph1-positive CML cases by Southern blot analysis of bcr rearrangement, and in 17 CML cases by a combination of Southern blot analysis and RT-PCR. By Southern blot, the breakpoint was not identified on M-bcr in three CML cases, of which one case showed the P210-type bcr/abl transcript and two cases showed the ALL-type (P190-type) bcr/abl transcript with or without P210 transcript. Later two cases showed unique hematological profiles such as thrombocytosis, mild myelofibrosis, and relative resistance to alkylating agents. Therefore, the present study suggests that expression of the P190-type transcript may affect clinical and hematological findings in CML.

Adult↗
PubMed1994

Effect of herbimycin A, an inhibitor of tyrosine kinase, on protein tyrosine kinase activity and phosphotyrosyl proteins of Ph1-positive leukemia cells.

Herbimycin A, a benzoquinonoid anasamycin antibiotic, preferentially inhibited the in vitro growth of Ph1-positive leukemia cell lines. On the other hand, genistein, which was developed as an inhibitor of receptor-type tyrosine kinase, and other protein kinase inhibitors showed no selective inhibition of Ph1-positive leukemia cell growth. Herbimycin A also displayed an abrogative effect on the transformation of murine hematopoietic cells by transfection with a bcr/abl oncoprotein-expressing retroviral vector. The antitumor action of herbimycin A on Ph1-positive leukemia cells is related to an inhibition of activity of bcr/abl protein tyrosine kinase and a subsequent reduction of the constitutive phosphotyrosyl proteins, however, the antibiotic has no effect on the expression of bcr/abl mRNA and oncoprotein. Therefore, herbimycin A may provide an important insight into the oncogenic action of bcr/abl oncoprotein and the future development of oncoprotein-targeted therapeutic agents.

Antibiotics, Antineoplastic↗
PubMed1994

In vivo antitumor activity of herbimycin A, a tyrosine kinase inhibitor, targeted against BCR/ABL oncoprotein in mice bearing BCR/ABL-transfected cells.

Herbimycin A, a benzoquinoid ansamycin antibiotic, has been shown to reverse the oncogenic phenotype of p60v-src transformed cells because of the inhibition of src protein tyrosine kinase. We previously demonstrated that herbimycin A displayed antitumor activity on the in vitro growth of Philadelphia chromosome-positive leukemia cells and BCR/ABL-transfected murine hematopoietic FDC-P2 cells through the inhibition of BCR/ABL protein tyrosine kinase. In this study, the transformed FDC-P2 cells were demonstrated to be tumorigenic in syngeneic DBA/2 mice. The intraperitoneal (i.p.) injection of the transformed tumor cells into DBA/2 mice induced infiltrations of abdominal organs, and then all of the mice died within time periods proportional to the cell numbers of inoculation. In mice that received an i.p. inoculation with greater than 1 x 10(5) cells, in vivo administration of herbimycin A by i.p. injection inhibited tumor formation and significantly prolonged survival time, and further, in mice inoculated with 1 x 10(4) cells, herbimycin A completely suppressed the in vivo growth of transformant FDC-P2 cells and brought about a complete remission. The present study revealed the in vivo efficacy of herbimycin A in mice bearing BCR/ABL-transfected cells.

Animals↗
PubMed1994

Aminotransferase catalysis applied to the synthesis of a PAF antagonist.

(R)-alpha-Methyl-3-pyridinebutanamine (5) was required as a key intermediate for production of the PAF antagonist [(R)-(E,E)-5-(4-methoxyphenyl)-N-1- methyl-4-(3-pyridinyl)butyl-2,4-decadienamide (1). A method meeting the requirements of technical simplicity and economic viability was developed using an aminotransferase ex. B. megaterium to catalyze a kinetic resolution of racemic alpha-methyl-3-pyridinebutanamine (3). 5-(3-Pyridinyl)-2-pentanone (4) produced from the (S)-enantiomer, with co-generation of alanine, is recycled by catalytic reductive amination.

Bacillus megaterium↗
PubMed1994

Experimental transmission of hantavirus infection in laboratory rats.

This study found a competent transmission of hantavirus between cagemates using congenitally T cell-deficient Rowett nude rats (rnu/rnu). Intraperitoneally infected immunologically normal rats (rnu/+) did not transmit the hantavirus to their normal cagemates (rnu/+) but did to Rowett nude rats (rnu/rnu). Thus, nude rats were shown to be highly susceptible to the hantavirus infection. Also, infected nude rats (rnu/rnu) discharged the infectious viruses, to cause a prevalence of infection among normal cagemates (rnu/+). The infection system demonstrated here using Rowett rats (rnu/rnu) may provide a useful model to study the mechanism of the hantavirus infection.

Animals↗
PubMed1994

Modification of recombinant human granulocyte colony-stimulating factor (rhG-CSF) and its derivative ND 28 with polyethylene glycol.

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) has been obtained from genetically engineered Escherichia coli as an unglycosylated protein. Both native glycosylated hG-CSF and rhG-CSF are rapidly cleared from the circulation, which may limit their effectiveness for clinical use. To improve this biological property, rhG-CSF and its derivative ND 28, which has a higher specific activity than does rhG-CSF, were modified with polyethylene glycol (PEG). Modified rhG-CSF and ND 28 in which 1 to 3 mol of PEG were bound, were purified by two-step chromatography and characterized by several methods. The results of their physicochemical characterization suggest that PEG-modification does not appreciably change the conformation of rhG-CSF and ND 28. As a result of the whole characterization, the PEG-modification of rhG-CSF and ND 28 enhanced the stability of rhG-CSF and ND 28 and decreased the plasma clearance rate, which led to more effective hemopoiesis.

Drug Stability↗
PubMed1994

Modulation of adriamycin resistance in human breast carcinoma MCF-7 cells in vitro and in vivo by medroxyprogesterone acetate.

The combination effect of adriamycin (ADM) and medroxyprogesterone acetate (MPA) was examined in vitro against human breast carcinoma MCF-7 and its ADM-resistant line (MCF-7/ADM). MCF-7 cells, which are positive for estrogen receptors, progesterone receptors and high-affinity MPA-binding activity, were more susceptible to the growth-inhibitory activity of ADM or MPA than MCF-7/ADM cells. A combination effect of ADM and MPA was observed against MCF-7/ADM cells, which are negative for steroid receptors, and furthermore against human nasopharynx carcinoma KB and its ADM-resistant line KB-A1. This combination effect of ADM and MPA against MCF-7/ADM cells was demonstrated to be synergistic by using the median effect plot method. The activity of MPA was almost equivalent to that of chlormadinone acetate or tamoxifen, greater than that of progesterone, and less than that of verapamil. The accumulation of ADM in MCF-7/ADM cells was enhanced by treatment with 10 microM MPA as well as 10 microM verapamil. The efflux of accumulated ADM from MCF-7/ADM cells was also partially inhibited by treatment with MPA or verapamil. MPA augmented the growth-inhibitory activity of ADM against MCF-7/ADM tumors inoculated into nude mice, although statistical significance was not observed. It is suggested that the clinical advantage of the combination of MPA with ADM against advanced breast cancers may be partly explained by the modulation of ADM resistance by MPA.

Animals↗
PubMed1994

Differential effect of duocarmycin A and its novel derivative DU-86 on DNA strand breaks in HeLa S3 cells.

Duocarmycin A (DUMA) and DU-86, a semisynthetic derivative of duocarmycins (DUMs) and a possible active form of KW-2189, both showed potent cell growth-inhibitory and cell-killing activities against human uterine cervix carcinoma HeLa S3 cells. Both drugs showed similar profiles of inhibition of macromolecular synthesis and influence on cell-cycle distribution. Namely, they inhibited [3H]thymidine uptake at lower concentrations than [3H]uridine or [3H]leucine uptake, suggesting that the inhibition of DNA synthesis is the primary site of their actions. Furthermore, they induced the accumulation of cells in early S phase. However, a significant difference was observed between these drugs in terms of DNA-fragmentation activity against HeLa S3 cells by using two independent methods, pulse-field gel electrophoresis and alkaline elution. DNA fragmentation was insignificant in the cells treated with DU-86, in contrast to the cells treated with DUMA. The analysis of DNA adducts in the cells revealed that DU-86 alkylated adenine quite selectively, while DUMA alkylated both adenine and guanine. These results suggest that the pyrrolidone ring of DUMA is responsible for its adduct formation with guanine and the subsequent DNA-fragmentation and inhibition of DNA synthesis, while DU-86 alkylated adenine and inhibited DNA synthesis through mechanisms other than DNA-fragmentation.

Adenine↗
PubMed1994

Basic fibroblast growth factor stimulates the competence phase of subcultured endothelial cells and the progression phase of primary cultured smooth muscle cells from rat aorta.

The proliferative effects of basic fibroblast growth factor (bFGF) on the cell cycle were compared in subcultured endothelial cells (EC) and primary cultured smooth muscle cells (SMC) from rat aorta by monitoring the starting time (an index of the competence phase) and rate (an index of the progression phase) of [3H]thymidine incorporation. Persistent treatment with bFGF (1, 10 and 30 ng/ml) reduced the starting time of EC proliferation in the presence of 1% fetal bovine serum (FBS) in a concentration-dependent manner. The starting time of [3H]thymidine incorporation into EC was reduced by a maximum of 4 h by pretreatment with bFGF for 12 h but not for 3 h. DNA synthesis in EC was inhibited by pretreatment with bFGF for 24 h. The rate of [3H]thymidine incorporation into SMC was accelerated both by persistent treatment with bFGF and pretreatment for 3 h in the presence of 3% FBS. In serum-free medium, bFGF (30 ng/ml) stimulated [3H]thymidine incorporation into SMC but not into EC after incubation for 36 h. Together, bFGF (10 ng/ml) and insulin (10 micrograms/ml) synergistically stimulated [3H]thymidine incorporation into EC, but insulin alone did not. These findings indicate that bFGF is a competence factor in EC and a progression factor in SMC from rat aorta.

Animals↗
PubMed1994

Dual modes of action of platelet-derived growth factor and its inhibition by trichostatin-A for DNA synthesis in primary cultured smooth muscle cells of rat aorta.

The effects of platelet-derived growth factor (PDGF) on the start and rate of DNA synthesis were investigated with or without (R)-trichostatin-A (TS-A) in primary cultured and synchronized smooth muscle cells (SMC) of rat aorta. After the SMC at the G0 phase were precultured with 10 and 100 ng/ml PDGF for 3 h and washed out,they were then stimulated with 3% fetal bovine serum (FBS). FBS-stimulated DNA synthesis was determined every 3 h for 24-30 h. The SMC pre-cultured with PDGF started DNA synthesis at an earlier time, dependent on the concentrations, suggesting an acceleration of competence. After the SMC were precultured with PDGF (30 ng/ml) plus TS-A (0.1, 0.3, 1.0 and 3.0 micrograms/ml) for 3 h and washed out, the SMC were then stimulated by 1% FBS. TS-A delayed the starting time of DNA synthesis in a concentration-dependent manner. During the prolonged culture with PDGF (1, 3, 10 and 100 ng/ml) and FBS (3%), the rate of DNA synthesis was more rapid than in cells pretreated with PDGF alone, suggesting an acceleration of progression. These results suggest that 1) PDGF stimulates DNA synthesis dually during the competence and progression phases, and 2) PDGF-induced competence is inhibited by TS-A in primary cultured SMC.

Animals↗
PubMed1994

Left ventricular function of the heart regressed by nifedipine in spontaneously hypertensive rats.

Left ventricular (LV) performance of the pharmacologically regressed heart in hypertension is still unclear. We compared LV function of the heart regressed by nifedipine with that of the hypertrophied heart in spontaneously hypertensive rats (SHR). Nifedipine (30 mg/kg/day in food) was given to 15-week-old male SHR for 20 weeks (n = 12). Age- and sex-matched SHR served as controls (n = 12). LV catheterization was performed using a micromanometer and cardiac output was determined by the thermodilution method. Hemodynamic studies were performed after washout of nifedipine (24 h), when blood pressure had returned to the untreated level. Peak pumping ability was assessed during acute volume loading with saline. Nifedipine significantly decreased blood pressure in conscious animals (222 +/- 11 to 201 +/- 12 mmHg, p < 0.01) and reduced LV weight (1.20 +/- 0.07 to 1.07 +/- 0.05g, p < 0.01). After washout of nifedipine, LV systolic and end-diastolic pressures, dp/dtmax and cardiac output determined under pentobarbital anesthesia were similar in the treated and untreated groups. Peak pumping ability during acute preload elevation was also similar in the 2 groups. Plasma norepinephrine was unaltered, and plasma renin activity was significantly lower in the treated rats (p < 0.05). These results indicate that nifedipine regressed LVH with a minimal reduction of blood pressure and without evidence of neurohumoral activation or volume retention. In conclusion, LV function of the heart regressed by nifedipine was preserved after a spontaneous rise in blood pressure and during acute preload elevation.

Animals↗
PubMed1994

Diabetic GK rat plasma but not normal Wistar rat plasma induces insulin-stimulated DNA synthesis in primary cultured smooth muscle cells in GK rat aorta.

We investigated the effect of diabetic plasma on insulin-stimulated DNA synthesis in primary cultured aortic smooth muscle cells (SMC) of the GK rat, a model of non-insulin-dependent diabetes mellitus, and compared it with that of Wistar normal rat plasma. We measured the incorporation of 3H-thymidine into cultured SMC. The diabetic plasma (3%) of GK rat, but neither the plasma (3%) of Wistar normal rat nor the plasma (3%) (not containing both insulin-like growth factor-I (IGF-I) and corticosterone) of Wistar hypophysectomized rat induced insulin-stimulated DNA synthesis in GK rat SMC. The responsiveness of SMC to insulin, not to IGF-I, was decreased remarkably by the diabetic state. The diabetic plasma of GK rat remarkably enhanced and the plasma of Wistar hypophysectomized rat weakly enhanced insulin-stimulated DNA synthesis in Wistar normal rat SMC. Corticosterone (20 nM) increased insulin-stimulated DNA synthesis in GK rat SMC but decreased it in Wistar normal rat SMC, using the plasma of Wistar hypophysectomized rat. Corticosterone levels were lower in GK rat plasma than in normal Wistar rat plasma. These results demonstrate that the enhancement of insulin-stimulated DNA synthesis in diabetic SMC by the diabetic plasma of GK rat may be due to neither IGF-I nor corticosterone but due to other factors.

Animals↗