Biomedical subjects

T Tokunaga

Publications and source records attributed to T Tokunaga.

At least 91 records · Page 5Linked to original sources

PubMed1998

Multidrug resistance-associated protein and mutant p53 protein expression in non-small cell lung cancer.

Multidrug resistance-associated protein (MRP) is one of the major factors for non-P-glycoprotein (PGp)-mediated multidrug resistance. We reported previously that overexpression of the MRP gene was related to the prognosis of non-small cell lung cancer (NSCLC). It is unclear how MRP expression is regulated in NSCLC. In this study, we examined MRP and mutant p53 expression in 107 NSCLCs by immunohistochemical procedures. Forty-seven (43.9%) of these 107 NSCLCs were positive for MRP in the cytoplasm. Mutant p53-positive NSCLC showed a significant correlation with MRP overexpression (P=.011). Coexpression of MRP and p53 in the same cells of NSCLC was confirmed by double-staining procedures. Twenty-six patients with MRP-positive tumors who underwent postoperative chemotherapy with MRP-related anticancer drugs (vindesine and etoposide) had significantly poorer prognoses than did those with MRP-negative tumors (P=.017). This correlation between MRP expression and prognosis was also seen in Stage III patients (P=.022) and in patients with squamous cell carcinoma (P=.062). NSCLC patients with coexpression of MRP and p53 showed poorer prognoses than did those without MRP and p53 (P=.014). These results suggested that MRP overexpression affected by mutant p53 had a significant effect on prognosis through atypical non-PGp-mediated multidrug resistance in NSCLC.

ATP-Binding Cassette Transporters↗

PubMed1997

A xenograft line of human teratocarcinoma established by serial transplantation in severe combined immunodeficient (SCID) mice.

We established a xenograft line of human teratocarcinoma (TC-1) and characterized the pluripotency of differentiation of the neoplastic cells. A teratocarcinoma specimen obtained from a primary mediastinal lesion (22-year-old male patient) was inoculated subcutaneously into severe combined immunodeficient (SCID) mice. The carcinoma formed tumors in the mice. We established a xenograft line by serial passage of the tumor in vivo. The primary tumor was composed of papillary and pseudoglandular nests of highly atypical epithelial cells with foci of glomeruloid structures. The metastatic cells showed apparent production of mucin and differentiation to striated muscle. The xenograft line TC-1 retained the basic histopathological features seen in the primary and metastatic cells. The xenograft line showed focal differentiation to cartilage through serial passages. Immunohistochemical studies with anti-alpha-fetoprotein (AFP) demonstrated positive immunoreactivity on the TC-1 cells. Serum AFP levels were also elevated in the TC-1-bearing SCID mice. The human teratocarcinoma xenograft line TC-1 will be useful for studying the differentiation mechanism in human totipotent stem cells.

Adult↗

PubMed1997

[Properties of extracellular products produced by group A streptococci isolated from patients with streptococcal toxic shock syndrome].

Extracellular products of group A streptococci isolated from patients with streptococcal toxic shock syndrome (STSS) were examined. The outline of the discussion of the 3 products are as follows; streptolysin O (SLO), proteinase and erythrogenic toxin. SLO and proteinase showed a relatively large amount of products more than erythrogenic toxin. SLO produced by group A streptococci isolated from the patient with STSS had an isoelectric point (pI) of 6.0 and a molecular weight of 64,000 and showed hemolytic activity in the presence of 2-mercaptoethanol (2-ME). Furthermore, the hemolytic activities of all components were inhibited by gamma-globulin and cholesterol. Proteinase had pIs of 8.7 and 8.9, and a molecular weight of 21,000. These data suggest that STSS clinical criteria probably reflects a characteristic of a large amount of products of individual S. pyogenes isolates.

Bacterial Proteins↗

PubMed1997

Efficacy of trimethoprim in murine experimental infection with a thymidine kinase-deficient mutant of Escherichia coli.

The antimicrobial activity of trimethoprim is antagonized by thymidine in in vitro susceptibility tests. The purpose of this investigation was to determine whether this antagonism also occurred during experimental infection in mice, which have high serum thymidine concentrations. We derived a mutant strain of Escherichia coli, TT-48, incapable of utilizing exogenous thymidine from parent strain E. coli KC-14 and then investigated the in vitro and in vivo antimicrobial activities of trimethoprim, sulfamethoxazole, cefdinir, and ofloxacin against these strains. E. coli TT-48 lacked the activity of thymidine kinase, which catalyzes the conversion of thymidine to thymidylate, but its growth curve remained close to that of the parent strain. The MICs of all of the antimicrobial agents tested, except cefdinir, for the mutant strain were slightly inferior to those for the parent strain. The bactericidal effect of trimethoprim against the parent strain was antagonized by thymidine at concentrations of more than 1 microg/ml, while that against the mutant strain was not affected by thymidine even at the highest concentration (10 microg/ml). The therapeutic efficacy of trimethoprim in experimental murine infections was significantly higher when the mutant rather than the parent strain was used, whereas the therapeutic efficacy of cefdinir or ofloxacin, whose antimicrobial action is independent of folic acid synthesis, was the same with both strains. Unexpectedly, sulfamethoxazole also had similar efficacy against both strains. Thus, high thymidine concentrations antagonized the antimicrobial activity of trimethoprim in vitro and in vivo.

Animals↗

PubMed1997

Radiofrequency catheter ablation of posteroseptal atrioventricular accessory pathways--location-specific electrographic characteristics of successful ablation sites.

The electrographic features of successful sites of radiofrequency catheter ablation were analyzed in 33 cases of posteroseptal accessory pathways and compared with those from 155 cases of free wall accessory pathways. The atrioventricular intervals in the posteroseptal cases were significantly longer than in the free wall cases (posteroseptal vs left and right free wall; 38 vs 33 and 26 msec, respectively; p < 0.05), and the incidences of continuous electrograms (42 vs 63 and 79%; p < 0.01) and PQS-pattern unipolar electrograms (50 vs 76 and 78%; p < 0.05) were significantly lower in the posteroseptal cases. The V-delta intervals in the posteroseptal cases were significantly longer than in the left free wall cases (17 vs 13 msec; p < 0.05), but shorter than in the right free wall cases (17 vs 23 msec; p < 0.05). No statistically significant difference in the incidence of Kent potentials among the 3 groups was observed. In radiofrequency ablation of posteroseptal pathways, the length of the atrioventricular interval and the incidences of continuous electrograms and PQS-pattern unipolar electrograms may be unsatisfactory even at the appropriate target site, but the V-delta interval and Kent potential are good indicators of suitable target sites.

Adolescent↗

PubMed1997

[A present situation of Foods for Specified Health Use (FOSHU) in Japan].

Seventy-nine products have been licensed as Foods for Specified Health Use (FOSHU) until 1997 by Ministry of Health and Welfare in Japan. Fifty-two of them are claiming Bifidogenicity and maintaining a good GI condition those which contain indigestible oligosaccharides or Bifidobacterium/Lactobacillus or dietary fiber. New type of FOSHU, concerning suppression of cholesterol absorption, mineral absorption, lowering blood pressure are increased recently.

Caseins↗

PubMed1997

Efferent targets of osseous CGRP-immunoreactive nerve fiber before and after bone destruction in adjuvant arthritic rat: an ultramorphological study on their terminal-target relations.

We report the ultramorphological characterization of the terminal-target relation of sensory peptidergic nerve fibers in healthy and diseased osseous tissues. Bone tissue sections were immunoelectronmicroscopically investigated for calcitonin gene-related peptide (CGRP), a neuropeptide widely distributed in sensory peptidergic fibers. Ultramorphological relation of the osseous CGRP-immunoreactive (ir) nerve terminals and their target cells was comparatively analyzed using healthy, arthritic, and postarthritic bone specimens from control and adjuvant-induced arthritic rats. Terminal-like profiles of the osseous CGRP-ir axons were evidenced in direct contact with the metaphyseal osteoblasts and osteoclasts of the control animals. Terminal-like profiles were also noted in the vicinity of the periosteal lining cells. Nonterminal-like profiles did not make intimate spatial relation to the cells/structures surrounding the nerve. Osseous CGRP-ir terminals and axons, which are either uncovered or thinly ensheathed by the supportive tissues, were extensively degenerated in adjuvant-induced infiltration, whereas larger fibers were relatively resistant. Numerous CGRP-ir axons with distinctive features reinnervated the postarthritic, ossifying periosteum. CGRP-ir axons appeared to reinnervate the eroded surface of metaphyseal bone and cartilage as early as the recruited osteoblasts resume osteogenesis in the postarthritic metaphysis. The observed terminal-target relations in the healthy and diseased bone tissues give an ultramorphological basis for the putative trophic, modulatory actions of CGRP innervation of the bone cells.

Animals↗

PubMed1997

Nonsurgical management of patients with blunt hepatic injury: efficacy of transcatheter arterial embolization.

OBJECTIVE: We evaluated the efficacy of transcatheter arterial embolization (TAE) for patients with blunt hepatic injury. SUBJECTS AND METHODS: Of 372 patients with trauma, 60 had evidence on CT of hepatic injury (Mirvis classification). Six of the 60 patients required emergency laparotomy and were excluded. Of the 54 remaining patients, 28 were classified as having high-grade hepatic injury (Mirvis classification of 3 or 4). All 28 underwent arteriography, and TAE was performed in single or multiple hepatic arterial branches when extravasation was seen. Angiography was repeated and cholescintigraphy was performed on patients with continued bleeding or biloma. RESULTS: Injuries detected were grade 1 (n = 13), grade 2 (n = 13), grade 3 (n = 20), and grade 4 (n = 8). The injury was correlated with the degree of hemoperitoneum seen on CT. Patients with low-grade injuries (Mirvis classification of 1 or 2) were treated conservatively, and no deaths or liver-related morbidity occurred. Of the 28 patients with high-grade injury, 15 also had angiographic evidence of extravasation and underwent TAE. The average fluid resuscitation volume was significantly larger in this group than in the other 13 patients with high-grade injuries who did not undergo TAE. Embolization was successful in all 15 patients, and the shock index was significantly reduced after TAE. All patients survived, with follow-up at 1-8 months (2.5 +/- 1.8 months, mean +/- SD). CONCLUSION: TAE is an effective alternative to surgery for patients with high-grade liver injury.

Adolescent↗

PubMed1997

YM-32890 A and B, new types of macrolide antibiotics produced by Cytophaga sp.

Two new types of macrolide antibiotics, YM-32890 A and B, have been isolated from the fermentation broth of cytophaga sp. YL-02905S. In this paper, the taxonomy of the producing strain, fermentation, isolation, structure elucidation, and biological activity of the antibiotics are reported. YM-32890 A inhibits the growth of staphylococci including a macrolide-resistant strain, but shows no antimicrobial activity against other Gram-positive, Gram-negative bacteria and yeast.

Anti-Bacterial Agents↗

PubMed1997

Inhibition of cholesterol biosynthesis by squalene epoxidase inhibitor avoids apoptotic cell death in L6 myoblasts.

The relationship between the inhibition of cholesterol biosynthesis and occurrence of myopathy was studied in L6 myoblasts using two lines of cholesterol biosynthesis inhibitors, 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor (simvastatin) and squalene epoxidase inhibitors (TU-2078 and NB-598). All inhibitors completely inhibited the cholesterol synthesis in L6 myoblasts at doses of 1 and 3 microM. Simvastatin (3 microM) inhibited the fusion reaction of L6 myoblasts followed by the severe cellular damage. The myoblasts also had failed actin fiber formation and creatinine phosphokinase (CPK) production. Additionally, this agent also caused apoptotic cell death in differentiated L6 muscle fiber, indicating that skeletal myopathy by HMG-CoA reductase inhibitors seems to occur not only in differentiating immature myoblasts but also in matured skeletal myotubes. In contrast, TU-2078 and NB-598 had no effect on the fusion reaction of differentiating myoblasts or on the cellular viability of muscle fiber at 3 microM, enough to completely inhibit cholesterol biosynthesis. It is conceivable that the mevalonate depletion and subsequent failure of ras farnesylation induced by simvastatin might cause the defects in differentiation and maintenance of the muscle fiber. Squalene epoxidase inhibitors did not show this adverse effect presumably because of the enzyme inhibition downstream of farnesyl synthesis. The present findings suggest the safe use of squalene epoxidase inhibitors in lipid-lowering therapy.

Actins↗

PubMed1996

Treatment with 15-deoxyspergualin induces temporal suppression of hemopoiesis and changes thymocyte populations in mice.

Effects of the immunosuppressive agent, 15-deoxyspergualin (DSG) on hemopoiesis and thymocyte populations were examined in mice. The numbers of bone marrow (BM) cells decreased after the administration of DSG for up to 8 days, and the extent of this decrease was correlated inversely to the time of administration. Conversely, the BM cells of DSG-treated mice had enhanced proliferative responses in vitro and in viv. Deoxymethylspergualin, DSG analogue, directly suppressed the proliferation of BM cells in vitro in a time and dose-dependent manner. Total thymocyte counts decreased following the administration of DSG. The numbers of immature, peanut agglutinin-binding (PNA+) thymocytes decreased notably. Minor changes were observed in the mature thymocytes and spleen cells of DSG-treated mice.

Animals↗

PubMed1996

Enzymes for anandamide biosynthesis and metabolism.

Anandamide is an endogenous ligand for cannabinoid receptors. We tried to isolate and purify "anandamide amidohydrolase' which hydrolyzes anandamide to arachidonic acid and ethanolamine. The enzyme activity was found in the microsomal fraction of porcine brain homogenate. The enzyme was solubilized in 1% Triton X-100, and partially purified by hydrophobic chromatography to a specific activity of about 0.3 mumol/min per mg protein (37 degrees C). Apparent K(m) for anandamide was about 60 microM. The enzyme reacted also with ethanolamides of linoleic, oleic, and palmitic acids at lower rates. This enzyme preparation also converted arachidonic acid to anandamide in the presence of 250 mM concentration of ethanolamine. Several lines of evidence including experiments using various inhibitors suggested that the anandamide synthase and amidohydrolase activities were derived from a single enzyme protein.

Animals↗

PubMed1996

P-glycoprotein-mediated acquired multidrug resistance of human lung cancer cells in vivo.

We examined whether the increased expression of P-glycoprotein (P-gp) encoded by the human multidrug resistance gene MDR1 is related to the acquired multidrug resistance of lung cancer in vivo. We estimated the chemosensitivity of lung cancer xenografts (LC-6, adenocarcinoma; Lu-24, small-cell cancer) by calculation of relative tumour growth (T/C%, treated/control) in vivo, based on statistical significance determined by the Mann-Whitney U test (P < 0.01, one-sided). MDR1 gene expression levels were evaluated by reverse transcription-polymerase chain reaction (RT-PCR) assay. P-gp production and P-gp localisation were examined by Western blotting and by immunohistochemical analysis respectively. LC-6 and Lu-24 were initially sensitive to both vincristine (VCR, 1.6 mg kg-1: LC-6, 45%; Lu-24, 39%) and doxorubicin (DOX, 12 mg kg-1: LC-6, 26%; Lu-24, 27%) in vivo. VCR-resistant variants (LC-6R, 66% and Lu-24R, 68%) selected with VCR (0.4 mg kg-1, x 9) significantly acquired cross-resistance to DOX (LC-6R, 55% and Lu-24R, 55% respectively). RT-PCR assay showed increased levels of MDR1 expression in LC-6R and Lu-24R with stable MDR1 expression levels. P-gp expression levels were elevated, and the percentage of P-gp-positive tumour cells increased in both LC-6R and Lu-24R. These results suggest that P-gp/MDR1 overexpression is related to acquired multidrug resistance in lung cancer in vivo.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1996

Hexamer palindromic oligonucleotides with 5'-CG-3' motif(s) induce production of interferon.

We have shown previously that 30-mer oligonucleotides containing hexamer palindromic sequences with 5'-CG-3' motif(s) induce interferon (IFN), activate natural killer (NK) cells, and thus exhibit tumor-regressing activity. The present study showed that a hexamer palindromic oligonucleotide (5'-AACGTT-3') alone induced IFN from mouse spleen cells when added with cationic liposomes. Accordingly, 32 kinds of hexamer palindromic oligonucleotides were tested for their ability to induce IFN in the presence of cationic liposomes. The results show that oligonucleotides with NACGTN and NTCGAN sequences exhibited the strongest activity. ACGCGT and TCGCGA also possessed moderate but significant activity. In contrast, palindromes without CG motif(s) were devoid of the activity. No hexamer oligonucleotides showed the activity when liposomes were absent. A complete palindromic sequence was essential as any single base substitution resulted in diminished activity. Among variety of palindromic oligonucleotides of different sizes with an ACGT sequence at the center, the tetramer oligonucleotide was without activity, whereas the activity of hexamer and longer oligonucleotides was almost equally high. These results strongly suggest that the minimal essential structure required for IFN induction is the hexamer palindromic sequence with CG motif(s).

Animals↗

PubMed1996

Novel 5-hydroxytryptamine (5-HT3) receptor antagonists. III. Pharmacological evaluations and molecular modeling studies of optically active 4,5,6,7-tetrahydro-1H-benzimidazole derivatives.

The R- and S-enantiomers of the 4,5,6,7-tetrahydro-1H-benzimidazole derivatives 3-8 were prepared by optical resolution. Each R-isomer, except for 3, was almost two orders of magnitude more potent than its S-isomer as a 5-hydroxytrptamine (5-HT3) receptor antagonist, as judged from they effect on the von Bezold-Jarisch reflex (B. J. reflex) in rats, the contraction of isolated guinea-pig colon and the receptor-binding affinity. The (--)-(R)-5-[(1-methyl-1H-indol-3-yl)carbonyl] derivative 6R.HCl (ramosetron = YM060) and (--)-(R)-5-[(1-indolinyl)carbonyl] derivative 4R.HCl (YM114 = KAE-393) given p.o. were hundreds of times more potent than 1 (ondansetron) and 2 (granisetron) in their inhibitory effects on cisplatin-induced emesis in ferrets and restraint stress-induced increases in fecal pellet output in rats. Three-dimensional molecular modeling studies suggested that the 'chiral selection' of the enantiomers might be influenced by the steric repulsion between the aromatic ring part and the conformationally restricted 4,5,6,7-tetrahydro-1H-benzimidazole ring in "equatorial-twist" conformation. In our pharmacophore model for the 5-HT3 receptor antagonist, a basic center exists at the left side of the aromatic-carbonyl plane when viewing from the aromatic part with the carbonyl oxygen atom upwards, whereas the "handedness" is ambiguous in the previously proposed model.

Animals↗

PubMed1996

Novel 5-hydroxytryptamine (5-HT3) receptor antagonists. IV. Synthesis and pharmacological evaluation of the oxidation products of (-)-(R)-5-[(1-methyl-1H-indol-3-yl)carbonyl] -4,5,6,7-tetrahydro-1H-benzimidazole hydrochloride (YM060: ramosetron).

In physicochemical and pharmacokinetic evaluations of (--)-(R)-5-[(1-methyl-1H-indol-3-yl)carbonyl] -4,5,6,7-tetrahydro-1H-benzimidazole hydrochloride 1 (YM060: ramosetron), which is a highly potent 5-hydroxytryptamine(-HT3) receptor antagonist, 4-hydroxy-6-[(1-methyl-1H-indol-3-yl) carbonyl]4,5,6,7-tetrahydro-1H-benzimidazole 2 was identified as a degradation product and metabolite of 1. The (--)-(4R,6S)-isomer 2 was synthesized from the diketone derivative 3, via the stereoselective reduction of 3 followed by the stereocontrolled epimerization of the (--)-(4S,6S)-isomer 10, the epimer of 2. The stereochemistry of 2 and 10 was determined by NMR and HPLC studies. Compounds 2 and 10 were found to be potent 5-HT3 receptor antagonists, like 1. Among the other oxidation products, the diketone derivatives 3 and 7 and the dihydroxylated derivative 4 retained antagonistic activity similar to that of ondansetron. This is of interest, because they do not possess the amine group which is known to be necessary for high affinity to the 5-HT3 receptor.

Animals↗

PubMed1996

Metabolism of barnidipine hydrochloride, a potent calcium antagonist, in rat and dog.

1. In vitro experiments in the rat indicated that barnidipine was metabolized extensively in the liver and was catalyzed by P450s. 2. After oral dosing, nine metabolites were identified in the urine and bile of rat and dog. No unchanged drug was detected in urine and bile. Ester hydrolysis and pyridine formation were the main metabolic pathways in urine in both species, whereas glucuronide conjugates of the debenzylated metabolite and the hydrolyzed pyrrolidine ester were noted in bile. 3. The metabolism of barnidipine in the rat and dog were qualitatively similar. Metabolites are generated by one or several of the following pathways: (a) N-debenzylation of the side chain, (b) hydrolysis of the pyrrolidine ester, (c) oxidation of the dihydropyridine ring to a pyridine ring, (d) hydrolysis of the methylester, (e) reduction of the nitro group to the amino group, and (f) conjugation of the generated metabolites with glucoronic acid.

Animals↗

PubMed1996

Kalimantacins A, B and C, novel antibiotics from Alcaligenes sp. YL-02632S. I. Taxonomy, fermentation, isolation and biological properties.

Novel antibacterial antibiotics, kalimantacins A, B and C, have been isolated from the fermentation broth of Alcaligenes sp. YL-02632S. In this paper, the taxonomy of the producing strain, fermentation, isolation and biological activities of kalimantacins are reported. Kalimantacins inhibit the growth of Staphylococcus aureus and S. epidermidis including multiple-drug resistant strains.

Alcaligenes↗