Biomedical subjects

Shoji Nagaoka

Publications and source records attributed to Shoji Nagaoka.

12 recordsLinked to original sources

PubMed2006

Superoxide dismutase as a target enzyme for Fe-porphyrin-induced cell death.

The cell viability of human cancer cell lines treated with [5,10-bis(N-methyl-4-pyridyl)-15,20-diphenyl]porphinatoiron(III) (cis-FeMPy(2)P(2)P) has been estimated. The cis-FeMPy(2)P(2)P is a superoxide dismutase (SOD) mimic in vitro that exhibited a significant toxicity in cancer cell lines. This toxicity is rather due to pro-oxidant properties of the iron-porphyrin in vivo. We have demonstrated that there was the relationship between the LD(50) values calculated from the viability of cancer cell lines treated with cis-FeMPy(2)P(2)P and the SOD activities of the cell lines. Furthermore, the inhibition of SOD by antisense S-oligonucleotide increased the cytotoxic effect of cis-FeMPy(2)P(2)P against cancer cells. These results suggest that SOD is a target enzyme for the cell death induced by cis-FeMPy(2)P(2)P as a new class of anticancer agents.

Base Sequence↗

PubMed2006

Enhancement of molecular-shape selectivity in high-performance liquid chromatography through multi-anchoring of comb-shaped polymer on silica.

Poly(octadecylacrylate) having plural trimethoxysilyl groups in the side chain (co-ODA(n)) was newly synthesized and immobilized onto silica through these groups. The liquid chromatographic behavior of silica-supported co-ODA(n) (Sil-co-ODA(n)) was investigated and compared with that of Sil-ODA(n), in which poly(octadecylacrylate) was immobilized through a terminal trimethoxy group at one side of the polymer main chain. Sil-co-ODA(n) showed higher selectivity for molecular shape, especially molecular planarity of PAHs than Sil-ODA(n).

Acrylates↗

PubMed2005

Molecular-length and chiral discriminations by beta-structural poly(L-alanine) on silica.

Poly(L-alanine)-grafted porous silica (Sil-Ala22) was prepared by polymerization of N-carboxyanhydride of L-alanine initiated by 3-aminopropylated silica. Its selective interaction with aromatic guest molecules was evaluated by the retention time in liquid chromatography using the column packed with Sil-Ala22. Sil-Ala22 showed a specific selective retention with discriminating molecular shapes, such as molecular length, linearity and planarity. This selectivity can be explained by a multiple pi-pi interaction with the carbonyl groups one dimensionally-aligned on the rigid beta-form structure in the peptide main chain. Chiral separation with Sil-Ala22 was also described.

Chromatography, Liquid↗

PubMed2004

Neuronal attachment and outgrowth on a micropatterned fluorinated polyimide surface.

In this study, we investigated the adhesion and neurite outgrowth of nerve cells on a fluorinated polyimide film micropatterned by ion irradiation. We used fluorinated polyimide because of its biocompatibility and excellent thermal and mechanical properties for ion irradiation. Rattus norvegicus chromaffin (PC12) cells were used for in vitro studies. The polyimide films were irradiated with He(+), Ne(+), or Kr(+) ions in a fluence range from 10(13) to 10(15) ions/cm(2) at 50 keV. PC12 cells selectively adhered to the polyimide film micropatterned by ion irradiation. The total neurite length for PC12 cells grown on the Kr(+)-irradiated film was the longest; the neurite length on the film irradiated by Kr(+) after 9 days was approximately five times longer than that for cells grown on the He(+)-irradiated film, i.e., 135 micro m. In addition, the PC12 differentiation rate on the ion-irradiated polyimide films also showed a similar trend to the total neurite length for PC12 cells cultured on the films: the rate decreased in the order Kr(+) > Ne(+) > He(+). This initial study indicated enhanced neurite outgrowth and differentiation of PC12 cells on fluorinated polyimide film micropatterned by ion irradiation.

Adsorption↗

PubMed2004

Surface modification of poly(L: -lactic acid) affects initial cell attachment, cell morphology, and cell growth.

The object of this study was to develop a highly porous scaffold to be used in regeneration of blood vessels, nerves, and other hollow tissues with small openings. Using the phase-inversion method and a mixture of water and methanol as a coagulating agent, we prepared highly porous flat membranes from poly(L: -lactic acid) (PLLA) with numerous pores both on the surface and in the interior of the membranes. Chinese hamster ovary (CHO) cells were cultured on the membranes to evaluate initial cell adhesion, cell proliferation, and cell morphology. Adhesion of CHO cells to PLLA was poor: the cells adhered at approximately half the rate observed with a tissue culture polystyrene dish (TCPS). In contrast, adhesion of cells to PLLA treated with a low-temperature oxygen plasma was good; the adhesion rate was the same as that on TCPS. The rate of cell proliferation on the treated membranes was no different from that on the nontreated membranes, but cell morphologies were quite different. The cells on the nontreated membranes were small and round and proliferated separately from one another. In contrast, the cells on the plasma-treated membranes proliferated in close contact with other cells, spreading out extensively in sheet-like formations. Since the plasma treatment not only accelerated cell adhesion but also enabled cells to proliferate in the form of sheets resembling biological tissue, we believe that oxygen-plasma treatment is extremely effective for modifying surfaces of materials used for tissue regeneration.

Animals↗

PubMed2004

Development of a novel polyimide hollow-fiber oxygenator.

We have developed a membrane oxygenator using a novel asymmetric polyimide hollow fiber. The hollow fibers are prepared using a dry/wet phase-inversion process. The gas transfer rates of O(2) and CO(2) through the hollow fibers are investigated in gas-gas and gas-liquid systems. The polyimide hollow fiber has an asymmetric structure characterized by the presence of macrovoids, and the outer diameter of the hollow fiber is 330 microm. It is found that the polyimide hollow-fiber oxygenator can enhance the gas transfer rates of O(2) and CO(2), and that the hollow fiber provides excellent blood compatibility in vitro and in vivo.

Animals↗

PubMed2003

Biocompatibility of fluorinated poly(organophosphazene).

We investigated neutrophil and platelet adhesion on a fluorinated poly(organophosphazene) in vitro. The results suggested that neutrophil and platelet adhesion on the poly(organophosphazene) only occurred on a few occasions, as observed by SEM. We demonstrated that the fluorinated poly(organophosphazene) showed excellent biocompatibility compared with the poly(organophosphazene) without the fluorinated side groups or PDMS. Additionally, we estimated the competitive plasma protein adsorption to the fluorinated poly(organophosphazene) using a gold-colloid-labeled immunoassay. Interestingly, the fluorinated poly(organophosphazene) film selectively adsorbed albumin when compared with gamma-globulin and fibrinogen, suggesting that a selective albumin adsorption on the film is responsible for the suppression of platelet adhesion.

Adsorption↗

PubMed2002

Selective cell death by water-soluble Fe-porphyrins with superoxide dismutase (SOD) activity.

We investigated the effect on cell death of reactive oxygen species induced by [[5,10 (or 5,15)-bis(N-methyl-4-pyridyl)-15,20 (or 10,20) diphenyl]porphinato]iron (cis-FeMPy(2)P(2)P or trans-FeMPy(2)P(2)P) with SOD activity. The SOD activities of the cis-FeMPy(2)P(2)P and trans-FeMPy(2)P(2)P were measured using stopped-flow kinetic analysis. The cell viability of four cell lines treated with cis-Fe-porphyrin, trans-Fe-porphyrin, mitomycin c (MMC), or cisplatin was estimated by the alamar blue exclusion assay of the modified MTT method. The amount of cis-FeMPy(2)P(2)P and trans-FeMPy(2)P(2)P in the Walker 256 cultured for 24 h was 4.0 and 2.6 fmolcell(-1), respectively, indicating that the plasma membrane permeability of the Fe-porphyrins depended on their structure. Cis-FeMPy(2)P(2)P selectively killed Walker 256 and H-4-II-E as cancer cells but not FR and BRL-3A as normal cells and showed a significant cytotoxicity for the cancer cells compared with trans-FeMPy(2)P(2)P, MMC and cisplatin. We believe that cis-FeMPy(2)P(2)P as an SOD mimic converts intracellular O(2)(*-) to H(2)O(2) and that H(2)O(2) or *OH causes DNA damage and induces cell death. This result suggests that for the SOD mimic, O(2)(*-) may be useful as a target molecule to induce selective cell death between cancer and normal cells and that a metalloporphyrin having SOD activity is a new class of anticancer agents.

Animals↗

PubMed2002

Biodegradation and biocompatibility of polyorganophosphazene.

We investigated biodegradation and biocompatibility of poly(organophosphazenes). We prepared poly(organophosphazenes) having different side chain groups. The blood compatibility of poly(organophosphazenes) containing fluorinated side groups, poly(bis[trifluoroethoxy]phosphazene) (PbFP) and poly([trifluoroethoxy][ethyl glycinate]phosphazene) (PFGP), without heparinization were evaluated in vitro. The deformation and aggregation of platelets adhered on PbFP and PFGP were not observed and they suppressed platelet activation. Additionally, PbFP and PFGP showed a higher degradation rate, despite their high hydrophobic nature. We found that the high mobility of water in PbFP and PFGP was one of the important factors facilitating their degradation. Their polymer structures were formed in a more open nature, indicating that water easily attacked the backbone of the phosphorus and nitrogen atoms in the poly(organophosphazene). On the other hand, the proliferation of HeLa cells cultured on poly(organophosphazene) was reduced compared with that on the control tissue culture polystyrene.

Biocompatible Materials↗

PubMed2002

Biomedical properties of nanofabricated fluorinated polyimide surface.

Cell adhesion, proliferation, and their orientation on the surface of fluorinated polyimide, 6FDA-6FAP, which was fabricated by curing treatment and the rubbing method, were investigated using a continuous cell line of human epithelial cells (adherent HeLa). The surface free energy of the fabricated 6FDA-6FAP was analyzed by the contact angle measurement and the topographic change of the surface was observed using atomic force microscopy. These properties were changed drastically by the treatment, and it was found that the adhesion and proliferation of the cells increased with the curing temperature. The noticeable finding was that the cells on the rubbed 6FDA-6FAP surface were modulated and aligned along with the rubbing direction, where nano-ordered grooves were formed, while the cells proliferated randomly on the unrubbed surface without such a nano-ordered structure.

Adsorption↗

PubMedDate not supplied

Design of metalloporphyrin-carbohydrate conjugates for a new superoxide dismutase mimic with cellular recognition.

Metalloporphyrin-carbohydrate conjugates have been synthesized as superoxide dismutase (SOD) mimics with cellular recognition. To synthesize the conjugates, aliphatic primary amino groups for conjugation were introduced, with the cationic pyridyl groups for the SOD activity of porphyrin preserved. The reductive amination between introduced amino groups and the reducing end of lactose was then carried out. The resulting conjugates consisting of manganese (Mn)-porphyrin surrounded by several lactose molecules possessed significant SOD activity and low cytotoxicity. Compared with metalloporphyrins having no lactose molecule, the recognition of the resulting conjugates by human hepatoma HepG2 cells increased. The cellular recognition was inhibited by competitors of beta-galactose. These results suggest that the Mn-porphyrin-lactose conjugates recognized the hepatic lectin on the cell surface.

Cell Line, Tumor↗

PubMedDate not supplied

Design of manganese porphyrin modified with mitochondrial signal peptide for a new antioxidant.

A new design of antioxidant, consisting of manganese (Mn) porphyrin and signal peptide for mitochondrial targeting, is reported. The resulting Mn-porphyrin-oligopeptide conjugate exhibited significant superoxide dismutase (SOD) activity and decomposed peroxynitrite (ONOO-). The new antioxidant caused the swelling of isolated mitochondria. By using the pH-sensitive drug carrier for intracellular delivery, furthermore, the new conjugate recovered the viability of lipopolysaccharide (LPS)-stimulated macrophage RAW 264.7 cells. These results suggest that the Mn-porphyrin modified with signal peptide for mitochondrial targeting is promising for a new class of antioxidants.

Amino Acid Sequence↗