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Biomedical subjects

Minoru Suzuki

Publications and source records attributed to Minoru Suzuki.

63 records · Page 4Linked to original sources
PubMed2002

Dictyterpenoids A and B, two novel diterpenoids with feeding-deterrent activity from the brown alga Dilophus okamurae.

In our continuing efforts to study the presence of biologically active compounds that control seaweed-herbivore interactions, we examined the presence of such chemicals in freshly collected Dilophus okamurae Dawson. Our results demonstrated the presence of two diterpenoids, named dictyterpenoid A (1) and dictyterpenoid B (2), having a novel carbon skeleton, along with 10 known diterpenes, 3-12. The structures of these novel metabolites were elucidated by spectroscopic and chemical methods. The isolated compounds showed feeding-deterrent activity against the young abalone Haliotis discus hannai.

Animals↗
PubMed2002

Halogenated metabolites from the new Okinawan red alga Laurencia yonaguniensis.

A novel brominated diterpene based on the rare neoirieane skeleton, named neoirietetraol (1), has been isolated along with a halogenated C15 acetogenin, (3Z)-laurenyne (2), from a new Laurencia species, L.yonaguniensis Masuda et Abe, species inedita, collected at Yonaguni Island, Okinawa Prefecture, Japan. The structures of these metabolites were elucidated by spectroscopic data (IR, 1H NMR, 13C NMR, 2D NMR, and MS). Neoirietetraol (1) was toxic to the brine shrimp (Altemia salina; LC50, 40.1 microM) and also showed weak antibacterial activities against two marine bacteria, Alcaligenes aquamarinus and Escherichia coli.

Alcaligenes↗
PubMed2002

Brominated labdane-type diterpenoids from an Okinawan Laurencia sp.

From an unidentified species of Laurencia collected from Okinawan waters two novel brominated metabolites, 1 and 2, along with known halogenated compounds, 2,10-dibromo-3-chloro-alpha-chamigrene (3) and microcladallene A (4), were isolated and identified. The structures of these new compounds were established as ent-labdane-type bromoditerpenes, (1S,3R,5S,6S,8S,9S,10R,13R)-1-acetoxy-3-bromo-6-hydroxy-8,13-epoxy-labd-14-ene (1) and (3R,5S,6S,8S,9S,10R,13R)-3-bromo-6-hydroxy-8,13-epoxylabd-14-en-1-one (2), by interpretation of their spectroscopic data as well as by X-ray crystallographic analysis.

Crystallography, X-Ray↗
PubMed2002

A novel ferromagnetic thermo-stent for plaque stabilization that self-regulates the temperature.

The purpose of this study is to investigate the vascular wall with a thermally self-regulating, cylindrical stent made of a low Curie temperature ferromagnetic alloy. Physiologic saline was circulated in the silicone model vessel implanted with the stent. The stent-temperature remained nearly constant for variable saline flows, saline temperatures, and magnetic flux densities. Stent implants of this type in human blood vessels could potentially enable thermotherapy and temperature determination without catheterization.

Animals↗
PubMedDate not supplied

Effects of p53 status and wortmannin treatment on potentially lethal damage repair, with emphasis on the response of intratumor quiescent cells.

PURPOSE: To examine the effects of p53 status and wortmannin treatment on potentially lethal damage repair, referring to the response of intratumor quiescent cells. METHODS: Human head and neck squamous cell carcinoma cells transfected with mutant TP53 (SAS/mp53) or with neo vector as a control (SAS/neo) were injected subcutaneously into both hind legs of Balb/cA nude mice. Mice bearing the tumors received 5-bromo-2'-deoxyuridine (BrdU) continuously to label all proliferating (P) cells in the tumors. The mice then received gamma-rays with or without subsequent wortmannin administration. Right after or 24 h after gamma-ray irradiation alone or 24 h after wortmannin administration following irradiation, the tumors were excised, minced, and trypsinized. The tumor cell suspensions thus obtained were incubated with a cytokinesis blocker (cytochalasin-B), and the micronucleus (MN) frequency in cells without BrdU labeling [quiescent (Q) cells] was determined using immunofluorescence staining for BrdU. The MN frequency in total (P+Q) tumor cells was determined from the tumors that were not pretreated with BrdU. RESULTS: On the whole, larger values of MN frequency and surviving fraction were observed in SAS/mp53 cells than in SAS/neo cells, and Q cells showed lower MN frequencies than total cells. Without wortmannin, SAS/neo tumor cells, especially Q cells within SAS/neo tumors, showed large potentially lethal damage repair (PLDR) capacities, compared with total or Q tumor cells within SAS/mp53 tumors that showed little PLDR capacity. Wortmannin treatment inhibited the PLDR in SAS/neo tumors very effectively, but showed no apparent effect on either total or Q tumor cells within SAS/mp53 tumors. CONCLUSION: PLDR in vivo was thought to be a p53-dependent event whether in total or Q tumor cell populations.

Androstadienes↗
PubMedDate not supplied

Radiological findings in total colon aganglionosis and allied disorders.

OBJECTIVE: The aim of this study was to review the radiological findings of three cases of total colon aganglionosis (TCA), hypoganglionosis, and immature ganglionosis, and to compare the differences in diagnosis and follow-up of these three disease entities. MATERIALS AND METHODS: Three neonates with neonatal onset of abdominal distension with vomiting were investigated, and the cases were diagnosed as TCA, hypoganglionosis, and immature ganglionosis, respectively. Radiological examination of each neonate was performed during the neonatal period and at follow-up. RESULTS: A plain abdominal radiograph showed massive abdominal bowel gas and multiple air-fluid levels in all cases. Barium enema findings including no transition zone, normal rectosigmoid index, reflux of barium into a dilated ileum, and retention of barium on delayed film were observed in all three cases. In aganglionosis and hypoganglionosis, a normal-sized colon, irregular contraction, shortening of the colon, and lack of redundancy were observed. In immature ganglionosis, microcolon was present but there was no shortening of the colon or loss of redundancy. Barium studies following ileostomy during childhood revealed no efficient peristalsis after the neonatal period in patients with aganglionosis and hypoganglionosis. Conversely, the patient with immature ganglionosis showed maturity of colonic function on barium studies after infancy. CONCLUSION: The clinical and radiological findings of TCA and allied disorders are similar in neonates. Sequential contrast intestinal studies could reveal peristalsis of the colon wall, suggesting maturity of the ganglion cells.

Barium Sulfate↗
PubMedDate not supplied

Applicability of the 2-nitroimidazole-sodium borocaptate-10B conjugate, TX-2060, as a 10B-carrier in boron neutron capture therapy.

BACKGROUND: It is difficult to deliver a therapeutic amount of 10B from conventional 10B-carriers for boron neutron capture therapy (BNCT) throughout the target tumors, especially into the intratumor hypoxic cells which have low uptake capacities. We evaluated the usefulness of 5 new 10B-compounds (TX-2041, TX-2042, TX-2058, TX-2059 and TX-2060) as 10B-carriers in BNCT. They are 2-nitroimidazole-sodium borocaptate-10B (BSH) conjugates, that is, hybrid compounds that have both a hypoxic tumor cell sensitizing unit under gamma-ray irradiation, 2-nitroimidazoles and a thermal neutron-sensitizing unit, BSH. MATERIALS AND METHODS: The 5 new compounds were administered to SCC VII tumor-bearing mice intraperitoneally. As a control, BSH was also administered in the same manner. Then, the 10B concentrations in the tumors and normal tissues were measured by gamma-ray spectrometry. Based on the data of the pharmacokinetics analyses, TX-2060 was chosen for a subsequent tumor-irradiation study. SCC VII tumor-bearing mice were continuously given 5-bromo-2'-deoxyuridine (BrdU) to label all proliferating (P) cells in the tumors, then treated with TX-2060 or BSH in the same manner as in the pharmacokinetics analyses. To obtain similar intratumor 10B concentrations during radiation exposure, irradiation with thermal neutrons or gamma-rays was started from 60 min after administration of the 10B-carrier. Right after irradiation, the tumors were excised, minced and trypsinized. The tumor cell suspensions thus obtained were incubated with cytochalasin-B (a cytokinesis blocker), and the micronucleus (MN) frequency in cells without BrdU-labelling (= quiescent (Q) cells) was determined using immunofluorescence staining for BrdU. Meanwhile, the MN frequency in total (P + Q) tumor cells was determined from the tumors that were not pretreated with BrdU. The clonogenic cell survival was also determined in mice given no BrdU. RESULTS: 10B distribution analyses in tumors, muscles, blood and liver indicated that TX-2060 has the most favorable characteristics for concentrating a sufficient amount of 10B in tumors and maintaining a high enough 10B concentration during irradiation. In addition, TX-2060 had a significantly stronger radio-sensitization effect with reactor thermal neutron beams than BSH on both total and Q cells in solid tumors. Further, TX-2060 clearly exhibited a radio-sensitization effect with gamma-rays, not only on total cells but also on Q and hypoxic tumor cells, which was not achieved by BSH. CONCLUSION: 10B-carrier, with a gamma-ray-sensitizing effect on tumor cells as well as the potential to keep 10B in tumors and sensitize tumor cells more markedly than conventional 10B-carriers, such as TX-2060, is a promising candidate for use in BNCT.

Animals↗
PubMedDate not supplied

Evaluation of hypoxic cell radio-sensitizers in terms of radio-sensitizing and repair-inhibiting potential. Dependency on p53 status of tumor cells and the effects on intratumor quiescent cells.

BACKGROUND: Intratumor quiescent (Q) cells and p53-mutated tumor cells are more difficult to control than intratumor proliferating (P) cells and p53 wild-type tumor cells, respectively. The usefulness of 3 hypoxic cell radio-sensitizers was compared in terms of a radio-sensitizing effect under aerobic and hypoxic conditions and a repair-inhibiting effect following irradiation on both Q and total (P + Q) cell populations in solid tumors. The dependency of these effects on the p53 status of tumor cells was also examined using tumor cell lines with identical genetic backgrounds except for their p53 status. MATERIALS AND METHODS: Human head and neck squamous cell carcinoma cells transfected with mutant TP53 (SAS/mp53) or with neo vector as a control (SAS/neo) were inoculated subcutaneously into both the hind legs of Balb/cA nude mice. The nude mice bearing the tumors and C3H/He mice bearing SCC VII tumors received 5-bromo-2'-deoxyuridine (BrdU) continuously to label all the P cells in the tumors. Tumor-bearing mice received gamma-ray irradiation while alive or following tumor clamping after being administered no drug, nimorazole, SR-2514 or misonidazole, or received no drug, nimorazole, SR-2514 or misonidazole straight after gamma-ray irradiation. For the group irradiated after receiving the drug, the tumors were excised immediately following irradiation, while for the group irradiated before receiving the drug, the tumors were excised 24 h after irradiation. The excised tumors were minced and trypsinized. The tumor cell suspensions thus obtained were incubated with cytochalasin-B (a cytokinesis blocker), and the micronucleus (MN) frequency in the cells without BrdU labelling (= quiescent (Q) cells) was determined using immunofluorescence staining for BrdU. Meanwhile, the MN frequency in the total tumor cell population was determined from the tumors that had not been pretreated with BrdU. The clonogenic cell survival was also determined in the mice given no BrdU. RESULTS: Both the radio-sensitizing effects under aerobic and hypoxic conditions and the repair-inhibiting effects following gamma-ray irradiation increased in the following order: nimorazole < SR-2514 < misonidazole in both total and Q cells in these 3 tumors. Both effects were more marked in the Q cells and p53-mutated tumors than in the total cells and p53-wild tumors, respectively. CONCLUSION: In terms of controlling radio-resistant Q tumor cells and p53-mutated tumor cells, the combination of radio-sensitizers and conventional radiotherapy is promising both for radio-sensitization and for repair-inhibition, but further study of the toxicity to normal tissues is needed.

Animals↗