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Biomedical subjects

Toshiyuki Kanamori

Publications and source records attributed to Toshiyuki Kanamori.

13 recordsLinked to original sources
PubMed2006

Manipulation of living cells by using PC-controlled micro-pattern projection system.

In order to meet the diversifying demand for the cell manipulation in the rapid progress of cell engineering, we developed a novel technique to capture the living cells on a culture substrate by irradiating light in a multiple manner. In clear contrast to the conventional cell patterning using the previously patterned substrate, the cell-retaining area can be defined even after cell seeding, and the captured cells can continue to grow freely beyond the defined area afterwards. After the light irradiation in arbitrary micropattern by using a newly developed apparatus and the process to remove non-captured cells including EDTA treatment, the highly contrasted cell patterns were formed with the precision of single cell size. Moreover, it was determined that the cell capturing arose just after light irradiation and diminished gradually in a time scale of 10h. It was confirmed that the cells maintained their viability well after the manipulation process including photo-induced cell capturing.

Animals↗
PubMed2006

Photoresponse of an aqueous two-phase system composed of photochromic dextran.

A novel aqueous two-phase system, which exhibits a reversible photoinduced phase separation, has been developed with photochromic dextran synthesized by substituting 0.3 mol % of the hydroxyl groups with the photochromic chromophore, 6-nitrospiropyran (NSp). For an aqueous solution containing this photochromic dextran and poly(ethylene glycol), it was observed that the solution, which had been uniform in the dark, quickly separated into two phases through blue light irradiation within 1 min and returned to the former uniform state spontaneously after heating at 50 degrees C for 1 h. Photoisomerization of NSp was confirmed to shift the phase separation temperature of this aqueous two-phase system by up to 30 degrees C.

Benzopyrans↗
PubMed2006

Photoresponsive properties of poly(N-isopropylacrylamide) hydrogel partly modified with spirobenzopyran.

A photoresponsive hydrogel was prepared by radical copolymerization of N-isopropylacrylamide, a vinyl monomer having a spirobenzopyran residue and cross-linker. By the observation of photoresponsive shrinking and the conductance change, it was confirmed that the hydrogel in an acidic condition exhibited drastic and rapid volume shrinkage and proton dissociation when it was irradiated with blue light. Further, to examine its application to the mass transfer control, we prepared a photo- and thermoresponsive gate membrane by introducing this photoresponsive hydrogel to the surface of a porous membrane. As the first demonstration of the photocontrol of membrane permeation for liquid, it was observed that its permeability for 1 mM HCl aqueous solution increased by 2 times in response to the blue light irradiation, and this photoresponse of the permeability was confirmed to be repeatable.

Journal Article↗
PubMed2006

Construction of a new artificial biomineralization system.

Hydroxyapatite (HAP) was mineralized in poly(vinyl alcohol) (PVA)/poly(acrylic acid) (PAA) complex hydrogel immersed in a salt solution containing PAA. The transparent HAP/polymer composite swelled in water depending on the HAP content; high HAP content gave small swelling and vice versa. The HAP content reached about 80 wt % at most. Observation of the cross section of the composite by energy-dispersive analysis of X-ray (EDAX) revealed that the composite consisted of two phases, i.e., a hard HAP-rich phase and a soft polymer-rich phase. In the HAP-rich phase, the space inside the hydrogel was occupied by HAP, while HAP was not mineralized in the polymer-rich phase. The nucleation seemed to take place, at first, at the middle depth of the hydrogel where the HAP-rich phase was formed. The HAP-rich phase grew its size toward the surface of the hydrogel at the cost of the polymer-rich phase. The presence of phosphorus, P, in the polymer-rich phase indicated the adsorption of HPO(4)(2-) on the polymer chain of the hydrogel via hydrogen bonding, accompanied with Ca(2+) because of electrostatic constraints. This adsorption of ions in addition to Donnan distribution of ions leads to the formation of a hypercomplex that can be regarded as a precursor of the HAP-rich phase. The change of the hypercomplex into the HAP-rich phase is discontinuous and hence concluded as a phase transition. By comparison of our mineralization system with the biomineralization system of HAP and CaCO(3), the physicochemical mechanism of the mineralization process in the present system was found to be similar to that in biological systems. In this sense, we termed the present system an artificial biomineralization system.

Acrylic Resins↗
PubMed2005

Poly(N-isopropylacrylamide)-graft-polypropylene membranes containing adsorbed antibody for cell separation.

We developed a novel selective cell-separation method based on using a poly(N-isopropylacrylamide)-graft-polypropylene (PNIPAAm-g-PP) membrane containing adsorbed monoclonal antibody specific to the target cell. This membrane was prepared by plasma-induced polymerization and soaking in an antibody solution at 37 degrees C. Poly(N-isopropylacrylamide) has a thermoresponsive phase transition: at 32 degrees C water-insoluble (hydrophobic) and water-soluble (hydrophilic) states interconvert. Adsorption of antibody onto PNIPAAm-g-PP membrane at 37 degrees C and its desorption at 4 degrees C was verified by fluorescence-microscopy of the PNIPAAm-g-PP membrane after soaking it in fluorescein-conjugated goat anti-mouse IgG in phosphate-buffered saline. PNIPAAm-g-PP membranes containing adsorbed anti-mouse CD80 monoclonal antibody preferentially captured mouse-CD80 transfected cells at 37 degrees C compared with membranes lacking antibody or containing anti-mouse CD86 monoclonal antibody. Detachment of captured cells from PNIPAAm-g-PP membranes was facilitated by washing at 4 degrees C because of the thermoresponsive phase transition of PNIPAAm. With this method, mouse CD80- or mouse CD86-transfected cells were enriched from a 1:1 cell suspension to 72% or 66%, simply and with high yield.

Acrylic Resins↗
PubMed2005

Separation of cultured strawberry cells producing anthocyanins in aqueous two-phase system.

A rapid and simple selection method of high-yield cells has been desired to establish highly productive cell lines for useful secondary metabolites. For this purpose, a new attempt was made to partition cultured plant cells in a poly(ethylene glycol)-dextran aqueous two-phase system (ATPS). The applicability of the ATPS in partitioning cultured strawberry cells (designated FAW) was investigated. The result of single-step partitioning in the ATPS supplemented with 0.4 mmol/kg lithium sulfate showed that FAW cells cultivated for 7 d under light-irradiation were separated into two cell populations with significantly different anthocyanin content. Additionally, the analysis technique of microscopic cell images showed that cells accumulating a high level of anthocyanin were partitioned completely into the bottom phase in a partitioning experiment of FAW cells cultivated for 10 d under light-irradiation in the ATPS supplemented with 1.8 mmol/kg potassium phosphate buffer. These results indicated that cell partitioning in ATPS increased the intracellular anthocyanin content and that the cultured strawberry cell population was heterogeneous in terms of cell surface properties. This is the first report of partitioning based on the heterogeneity of the cell surface properties correlated with the intracellular secondary metabolism in cultured plant cells. Our results also suggested that the ATPS was appropriate as a large-scale method for selecting useful cell lines among the cultured plant cells.

Anthocyanins↗
PubMed2004

Probing the dielectric environment surrounding poly(N-isopropylacrylamide) in aqueous solution with covalently attached spirobenzopyran.

The dielectric environment surrounding poly(N-isopropylacrylamide) in aqueous solution was investigated by probing with spirobenzopyran covalently attached as a side chain to the polymer main chain. Inherent characteristics of the spirobenzopyran chromophore were analyzed, and the chromophore was confirmed to be suitable to probe the local polar condition around the polymer. Measurements for an aqueous polymer solution at various temperatures elucidated that the dielectric environment surrounding the polymer changed continuously even in the temperature range far below the lower critical solution temperature. This result suggested that the local and weak orientation of water molecules around the polymer diminished continuously in a preliminary stage of shifting to thermally induced phase separation. The dielectric environment surrounding thermoresponsive polymer in aqueous solution was investigated by probing with spirobenzopyran covalently attached as a side chain to the polymer main chain.

Acrylic Resins↗
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

Development of a fluorinated polyimide hollow fiber for medical devices.

We fabricated an asymmetric polyimide hollow fiber for medical devices. A dry/wet phase inversion process was applied to a spinning process to prepare the hollow fiber. The outer diameter was 330 microm with a wall thickness of 70 microm. Transfer rates of O2 and CO2 in the asymmetric polyimide fiber were 6.9 x 10(-3) and 5.5 x 10(-3) cm3 (STP)/(cm2 s cmHg), respectively, which are approximately 10 times higher than those measured in the Menox and Si-polypropylene fibers of the presently available membrane oxygenators. The blood compatibility of the polyimide hollow fiber was evaluated in vivo, indicating that polyimide had excellent blood compatibility when compared with silicone-coated fiber. Additionally, we fabricated a novel porous membrane with three-dimensional fine structure from cylindrical microscale pores and examined possibility of a porous membrane for use in hemodialysis.

Animals↗
PubMed2003

Effect of an angiotensin II type 1 receptor blocker, valsartan, on neurohumoral factors in patients with hypertension: comparison with a long-acting calcium channel antagonist, amlodipine.

This study compared the effects of amlodipine and valsartan on the sympathetic nervous system, the renin-angiotensin-aldosterone system, and brain natriuretic peptide, which are considered important parameters of the long-term prognosis. Seventy-three elderly patients, who had received antihypertensive treatment for more than 6 months with amlodipine, participated in this study. They were randomized to the V group (n = 36) and switched to valsartan from amlodipine, or to the A group (n = 37), which continued treatment with amlodipine. The dose of valsartan was set as that which controlled the blood pressure to the same extent as before switching. Blood samples were measured before and after 6 months of therapy. Data were analyzed by two-way analysis of variance with the Newman-Keuls test. In the V group, norepinephrine (from 597.0 +/- 52.9 to 475 +/- 43.8 pg/ml, p < 0.05) and aldosterone (from 74.5 +/- 7.0 to 53.9 +/- 5.3 pg/ml, p < 0.001) were decreased significantly after 6 months, although norepinephrine and aldosterone levels were unchanged in the A group. However, brain natriuretic peptide did not show a difference between the two groups. These findings suggested that valsartan is probably superior to amlodipine with respect to less activation of the sympathetic nervous system and preventing upregulation of the renin-angiotensin-aldosterone system.

Aged↗
PubMedDate not supplied

In situ control of cell adhesion using photoresponsive culture surface.

A photoresponsive culture surface (PRCS) allowing photocontrol of cell adhesion was prepared with a novel polymer material composed of poly(N-isopropylacrylamide) having spiropyran chromophores as side chains. Cell adhesion of the surface was drastically enhanced by the irradiation with ultraviolet (UV) light (wavelength: 365 nm); after subsequent cooling and washing on ice, many cells remained in the irradiated region, whereas most cells were removed from the nonirradiated region. The cell adhesion of the PRCS, which had been enhanced by previous UV irradiation, was reset by the visible light irradiation (wavelength 400-440 nm) and the annealing at 37 degrees C for 2 h. Also it was confirmed that the regional control of cell adhesion was induced several times by repeating the same series of operations. Further, living cell patterning with the 200 microm line width was produced readily by projecting UV light along a micropattern on the PRCS on which the living cells had been seeded uniformly in advance. By using a fluorescent probe that stains living cells only, it was confirmed that the cells maintained sufficient viability even after UV light irradiation followed by cooling and washing.

Acrylic Resins↗