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Biomedical subjects

S Nagaoka

Publications and source records attributed to S Nagaoka.

At least 19 recordsLinked to original sources
PubMed2003

Interaction between fibroblast cells and fluorinated polyimide with nano-modified surface.

In this study, we investigated the effect of surface nano-modification of aromatic fluorinated polyimide (6FDA-6FAP) derived from 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 2,2'-bis (4-aminophenyl) hexafluoropropane (6FAP) on the interaction with proteins and cells. The surface of 6FDA-6FAP was modified by surface-rubbing showed nano-ordered stripes along the rubbing direction. The rat fibroblast FR cells formed multicellular spheroids with high cell density on the rubbed surface then expressed excellent collagen production similarly in vivo, while on the non-modified surface the cells formed two-dimensional monolayers and the collagen production was negligible. The modulation of cell function by the surface nano-modification along with surface micro-modification may be one of the most important considerations during the design and manufacture of novel biochips or tissue engineering materials.

Animals↗
PubMed2002

Biocompatibility of fluorinated polyimide.

Contact between blood and biomaterial triggers a complex series of events including protein adsorption, leukocyte adhesion and activation, and complement activation. In this article, a series of fluorinated polyimides cured at a different temperatures was prepared, and the biocompatibility of the membranes was evaluated using in vitro protein adsorption, neutrophil adhesion, and complement activation experiments under static conditions. We found that protein adsorption, neutrophil adhesion, and complement activation for the polyimides significantly depends on the curing temperature and decreases with an increase in the temperature and that the polyimide has a good biocompatibility compared with poly(styrene) and polydimethylsiloxane. We concluded that the rearrangement of molecules such as CF(3), sulfone, and ketone at the outermost surface occurs because of curing, which induces an increase in the hydrophobicity and that the cured polyimide suppresses protein adsorption, neutrophil adhesion, and complement activation because of its high hydrophobicity and low surface free energy.

Adsorption↗
PubMed2002

Aquatic animal research in space station and its issues--focus on support technology on nitrate toxicity.

We studied the effects of accumulated nitrate in water on the spawning, hatching and development of medaka using a simple nitrifying filter and a combined filter having both nitrifying and denitrifying capabilities. A nitrate concentration of 100 mg NO3(-)-N/L was clearly of lethal toxicity to fish when they were exposed to nitrate in both adult and the growing phases. A nitrate concentration of 75 mg NO3(-)-N/L reduced the fertilization rate, delayed the hatching time and reduced the hatching rate of the eggs laid by adults and decreased the growth rate of juveniles. In addition, nitrate accumulations as low as 50 mg NO3(-)-N/L remarkably retarded spawning and lowered the number of eggs laid by fish exposed in the juvenile phase. The effects on the reproduction system may be initiated by a low concentration, approximately 30 mg NO3(-)-N/L.

Animals↗
PubMed2002

LET distributions from CR-39 plates on Space Shuttle missions STS-84 and STS-91 and a comparison of the results of the CR-39 plates with those of RRMD-II and RRMD-III telescopes.

The LET distributions during the Space Shuttle missions STS-84 (altitude 270-412 km, average 375 km; inclination angle, 51.6 degrees) and STS-91 (altitude 328-397 km, average 373 km; inclination angle, 51.6 degrees) were measured using CR-39 plastic nuclear track detectors. A correction for the dip-angle dependence of the track-formation sensitivity of the CR-39 plates was applied to the data analysis. The absorbed doses and the dose equivalents around RRMD Detector Units, estimated from the LET distributions in the LET region of 4-200 keV/micrometers, fluctuated with standard deviations of +/- 21% to +/- 35% in both flight experiments. The LET distributions obtained from the CR-39 plates agreed well with that obtained from RRMD-II in STS-91. However, the particle fluxes obtained from RRMD-III in STS-84 and STS-91 were two or three times higher than those obtained from RRMD-II and the CR-39 plates. It was concluded that the LET distributions obtained from RRMD-II and the CR-39 plates in the present flight experiments did not include the contribution of target-fragmented secondary heavy particles produced by low-LET particles, such as relativistic or semi-relativistic protons and helium ions, whereas RRMD-III was able to detect these secondary particles because of its low triggering level.

Cosmic Radiation↗
PubMed2001

Identification of novel hypocholesterolemic peptides derived from bovine milk beta-lactoglobulin.

This study was designed to clarify the mechanisms of hypocholesterolemic action of beta-lactoglobuline tryptic hydrolysate (LTH) and to identify the novel hypocholesterolemic peptide derived from LTH by screening using Caco-2 cells and animal studies. Serum and liver cholesterol levels were significantly lower in rats fed LTH than in those fed casein tryptic hydrolysate (CTH). The present study suggests that the inhibition of micellar solubility of cholesterol which causes the suppression of cholesterol absorption by a direct interaction between cholesterol mixed micelles, and LTH in the jejunal epithelia is part of the mechanism underlying the hypocholesterolemic action of LTH. Though no one could trace the hypocholesterolemic peptide to any protein origin, we identified, for the first time, a novel hypocholesterolemic peptide, Ile-Ile-Ala-Glu-Lys (IIAEK). Surprisingly, the present study provides the first direct evidence that a new hypocholesterolemic peptide derived from beta-lactoglobuline can powerfully influence serum cholesterol levels and exhibit a greater hypocholesterolemic activity in comparison with that of medicine, beta-sitosterol, in animal studies.

Administration, Oral↗
PubMed2001

Cell death by reactive oxygen species generated from water-soluble cationic metalloporphyrins as superoxide dismutase mimics.

We investigated the effect on cell death of reactive oxygen species induced by water-soluble cationic metalloporphyrins with superoxide dismutase (SOD) activity. The SOD activity of 5,10,15,20-tetrakis(4-N-methylpyridyl)]porphine (MPy(4)P) containing Fe, Mn or Cu was measured using a cytochrome c assay by the xanthine/xanthine oxidase system and stopped-flow kinetic analysis. Cell viability of four cell lines treated with metalloporphyrins, mitomycin c (MMC), or cisplatin was estimated by a trypan blue exclusion assay. FeMPy(4)P with a high SOD activity showed a significant cytotoxicity compared with MMC and cisplatin, while CuMPy(4)P without SOD activity exhibited no cytotoxicity. However, MnMPy(4)P showing an SOD activity as high as that of FeMPy(4)P did not indicate cytotoxicity. These findings suggest that FeMPy(4)P as SOD mimic converts intracellular O2(*-) to H(2)O(2) and that it rapidly reacts with H(2)O(2) to form *OH, causing DNA damage and inducing cell death. On the other hand, MnMPy(4)P did not participate in the Fenton reaction, so that DNA damage in the cells treated with MnMPy(4)P was not observed. In addition, the cytotoxicity by the metalloporphyrin was inversely correlated with the SOD activity of the cells and the selective damage at cellular and DNA levels was confirmed. We believe that for an anticancer drug with antioxidant ability O(2)(*-) is useful as a target molecule to induce selective cell death between cancer and normal cells and that metalloporphyrins showing SOD activity and Fenton-like reaction are a new class of anticancer agents.

Animals↗
PubMed2001

Differentiation of Dictyostelium discoideum vegetative cells into spores during Earth orbit in space.

We reported previously that emerged amoebae of Dictyostelium (D.) discoideum grew, aggregated and differentiated to fruiting bodies with normal morphology in space. Here, we investigated the effects of space radiation and/or microgravity on the number, viability, kinetics of germination, growth rate and mutation frequency of spores formed in space in a radiation-sensitive strain, gamma s13, and the parental strain, NC4. In gamma s13, there were hardly spores in the fruiting bodies formed in space. In NC4, we found a decrease in the number of spores, a delay in germination of the spores and delayed start of cell growth of the spores formed in space when compared to the ground control. However, the mutation frequency of the NC4 spores formed in space was similar to that of the ground control. We conclude that the depression of spore formation might be induced by microgravity and/or space radiation through the depression of some stage(s) of DNA repair during cell differentiation in the slime mold.

Animals↗
PubMed2001

The effects of microgravity on induced mutation in Escherichia coli and Saccharomyces cerevisiae.

We examined whether microgravity influences the induced-mutation frequencies through in vivo experiments during space flight aboard the space shuttle Discovery (STS-91). We prepared dried samples of repair-deficient strains and parental strains of Escherichia (E.) coli and Saccharomyces (S.) cerevisiae given DNA damage treatment. After culture in space, we measured the induced-mutation frequencies and SOS-responses under microgravity. The experimental findings indicate that almost the same induced-mutation frequencies and SOS-responses of space samples were observed in both strains compared with the ground control samples. It is suggested that microgravity might not influence induced-mutation frequencies and SOS-responses at the stages of DNA replication and/or DNA repair. In addition, we developed a new experimental apparatus for space experiments to culture and freeze stocks of E. coli and S. cerevisiae cells.

Alkylating Agents↗
PubMed2001

Alkylating agent (MNU)-induced mutation in space environment.

In recent years, some contradictory data about the effects of microgravity on radiation-induced biological responses in space experiments have been reported. We prepared a damaged template DNA produced with an alkylating agent (N-methyl-N-nitroso urea; MNU) to measure incorrect base-incorporation during DNA replication in microgravity. We examined whether mutation frequency is affected by microgravity during DNA replication for a DNA template damaged by an alkylating agent. Using an in vitro enzymatic reaction system, DNA synthesis by Taq polymerase or polymerase III was done during a US space shuttle mission (Discovery, STS-91). After the flight, DNA replication and mutation frequencies were measured. We found that there was almost no effect of microgravity on DNA replication and mutation frequency. It is suggested that microgravity might not affect at the stage of substrate incorporation in induced-mutation frequency.

Alkylating Agents↗
PubMed2001

Measurements of LET-distribution, dose equivalent and quality factor with the RRMD-III on the Space Shuttle Missions STS-84, -89 and -91.

Dosimetric measurements on the Space Shuttle Missions STS-84, -89 and -91 have been made by the real-time radiation monitoring device III (RRMD-III). Simultaneously, another dosimetry measurement was made by the Dosimetry Telescope (DOSTEL) on STS-84 and by the tissue-equivalent proportional counter (TEPC) on STS-91. First, the RRMD-III instrument is described in detail and its results summarized. Then, the results of DOSTEL and TEPC are compared with those of the RRMD-III. Also, the absorbed doses obtained by TLD (Mg2SiO4) and by RRMD-III on board STS-84 and -91 are compared.

Atlantic Ocean↗
PubMed2001

Regulation of interleukin-6 expression in human dental pulp cell cultures stimulated with Prevotella intermedia lipopolysaccharide.

Interleukin (IL)-6 expression in human dental pulp cell cultures after stimulation with Prevotella intermedia lipopolysaccharide (LPS) was investigated by Northern blot analysis, enzyme immunoassay, and bioassay. The IL-6 mRNA expression began to increase after 1 hr and continued after up to 8 hr of exposure on stimulation with 10 microg/ml of P. intermedia LPS. The bioactivity was dose-dependent on the concentration of P. intermedia LPS (0 to 100 microg/ml). The IL-6 mRNA expression was inhibited by actinomysin D and super-induced by cycloheximide. Anti-CD14 monoclonal antibody (MY4) inhibited the IL-6 mRNA expression when administered at a 0.5 microg/ml concentration before stimulation with P. intermedia LPS at 1 microg/ml. The immunoregulatory cytokines (interferon-gamma, IL-10, and IL-4) inhibited LPS-induced IL-6 production with a combined treatment. These results suggest the IL-6 expression by pulp cell cultures is CD14-dependent and regulated at the transcriptional level, and a combined treatment with immunoregulatory cytokines may be effective for control of pulpal inflammation due to P. intermedia LPS.

Antibodies, Monoclonal↗
PubMed2001

Molecular characterization of Bombyx mori cytoplasmic polyhedrosis virus genome segment 4.

The complete nucleotide sequence of the genome segment 4 (S4) of Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) was determined. The 3,259-nucleotide sequence contains a single long open reading frame which spans nucleotides 14 to 3187 and which is predicted to encode a protein with a molecular mass of about 130 kDa. Western blot analysis showed that S4 encodes BmCPV protein VP3, which is one of the outer components of the BmCPV virion. Sequence analysis of the deduced amino acid sequence of BmCPV VP3 revealed possible sequence homology with proteins from rice ragged stunt virus (RRSV) S2, Nilaparvata lugens reovirus S4, and Fiji disease fijivirus S4. This may suggest that plant reoviruses originated from insect viruses and that RRSV emerged more recently than other plant reoviruses. A chimeric protein consisting of BmCPV VP3 and green fluorescent protein (GFP) was constructed and expressed with BmCPV polyhedrin using a baculovirus expression vector. The VP3-GFP chimera was incorporated into BmCPV polyhedra and released under alkaline conditions. The results indicate that specific interactions occur between BmCPV polyhedrin and VP3 which might facilitate BmCPV virion occlusion into the polyhedra.

Amino Acid Sequence↗
PubMed2001

Gas transfer and blood compatibility of asymmetric polyimide hollow fiber.

We have fabricated an asymmetric polyimide hollow fiber for use as a membrane oxygenator. A dry/wet phase inversion process has been applied to a spinning process to prepare the hollow fiber. The fiber structure consisted of a complete defect-free skin layer and a porous substructure characterized by the presence of an open-cell structure and macrovoids. The outer diameter was 480 microm with a wall thickness of 50 microm. Transfer rates of O2 and CO2 in the asymmetric polyimide fiber were 2.3 x 10(-5) and 1.1 x 10(-4) (cm3 (STP)/(cm2 s cmHg)), respectively, which were four times higher than those measured in the polydimethylsiloxane (PDMS) fiber of the presently-available membrane oxygenator. The (QO2/QN2) selectivity of the polyimide fiber was 4.9, indicating that the surface skin layer is essentially defect-free. The blood compatibility of the polyimide hollow fiber has been evaluated in vitro and in vivo. The polyimide had an excellent blood compatibility when compared with PDMS.

Adsorption↗
PubMed2001

Unique occurrence of the 1CF11 carbohydrate epitope in primate saliva.

We examined a large number of individual human and animal saliva samples for the reactivity with ICF11, a mouse monoclonal antibody previously produced for the characterization of human milk mucin and apparently recognizing a certain carbohydrate antigenic structure shared by various human glycoproteins in secretions. The results obtained here confirm the unique occurrence of ICF11 epitope in each and every saliva sample from humans and Old world monkeys as well, though a vast variety was observed among individual saliva samples in the immunological reactivity with ICF11.

Animals↗
PubMed2001

Soy protein hydrolyzate with bound phospholipids reduces serum cholesterol levels in hypercholesterolemic adult male volunteers.

This study was done to evaluate the effects of soy protein hydrolyzate with bound phospholipids (c-SPHP), on the serum cholesterol levels in hypercholesterolemic subjects over a three-month period. Subjects were Taiwanese adult male volunteers whose serum total cholesterol levels were above 220 mg/dl. Twenty-one subjects were divided into three groups randomly, and each group was given c-SPHP zero, 3, or 6 g per day. Test diets were orally administered in a powdered drink form that contained c-SPHP or casein hydrolyzate (placebo). The subjects were given the test diet four times daily. The study consisted of a two-week pre-feeding period, a three-month feeding period, followed by a two-week post-feeding period. After 3 months of c-SPHP administration, 3 g per day, serum total cholesterol decreased significantly from the initial level (15.0%, p<0.01) and compared with the placebo group (p<0.05). Furthermore, LDL-cholesterol decreased significantly (27.7%, p<0.01) and the LDL/HDL ratio also decreased significantly (47.4%, p<0.01) from the initial levels. These effects of c-SPHP were dose-dependent. This study suggests that c-SPHP has remarkable improving effects on the serum cholesterol levels in hypercholesterolemic subjects.

Adult↗
PubMed2001

Human milk bile-salt-stimulated lipase is extremely reactive with the monoclonal antibody 1CF11 which recognizes a human-specific carbohydrate antigen.

1CF11 (Kanamaru, Y. et al.; Biochem. Biophys. Res. Commun., 249, 618-623, 1998) is a monoclonal antibody obtained after being raised in a mouse by injection of human milk MUC1 mucin as the antigen. Its reactivity was found to be unique in that it only reacts with a carbohydrate epitope shared by glycoproteins in human secretions, while its chemical nature is still unknown. Since a glycoprotein of Mr 135,000 (135K) in human milk was found to react extremely strongly with this antibody, we intended in this study to isolate the glycoprotein by a combination of various chromatographic techniques and identify it. It is a human milk bile-salt-stimulated lipase. By comparison of its immunoreactivity and glycan structures so far reported with those of lactoferrin from human milk, it is suggested that the epitope recognized by mAb ICF11 could be a human-specific novel glycan.

Amino Acid Sequence↗
PubMed2001

[A clinical investigation of oro-maxillary sinus-perforation due to tooth extraction].

Oro-maxillary sinus perforation occurs occasionally at the extraction of a maxillary tooth, and it may be a cause of maxillary sinusitis or antro-oral fistula. Our purpose was to investigate the most frequent site of perforation, and to understand the clinical course of patients after perforation. We examined 2,038 maxillary teeth extracted from 1,337 patients (473 males and 864 females) at the First Department of Oral and Maxillofacial Surgery, Tokyo Medical and Dental University, from January 1991 to December 1993. Perforation occurred in 77 of all 2,038 teeth (3.8%). Of these, 38 teeth were from males (38/733; 5.2%), and 39 were from females (39/1,305; 3.0%). The perforation rate was significantly higher in males. Perforation occurred most often with extraction of an upper first molar, and in the third decade of life. The perforation rate gradually decreased with higher age. We classified 38 cases into 3 categories according to panorama X-P: 1) The tip of the root crossed over the bottom line of the maxillary sinus (29 cases), 2) Not crossed over distinctly (4 cases), 3) Just lie on, or whether the tip of the root crossed over the bottom line of the maxillary sinus was not distinct (5 cases). As to treatment, 30 perforations (39.0%) closed spontaneously in the course of observation, irrigation with physiological saline was used in 43 cases (55.8%), radical sinusotomy accompanied by closure of the perforation was performed in 4 cases, and only flap closure was used in 7 cases. There were no cases of relapse.

Adult↗