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ACKNOWLEDGMENT Our respected Professor, Satoru Mashimo, died on March 29th, 1996. We shall all miss him very much. ...doi:10.1063/1.1147128 fatcat:v2ezldpk4jhflgvtu2vmcoibx4
Cell culture medium, which must be discarded during medium change, may contain many cells that do not attach to culture plates. In the present study, we focused on these floating cells and attempted to determine their usefulness for cartilage regeneration. We counted the number of floating cells discarded during medium change and compared the proliferation and differentiation between floating cells and their adherent counterparts. Chondrocyte monolayer culture at a density of 5 × 10 3 cells/cmdoi:10.2220/biomedres.33.281 pmid:23124248 fatcat:7rspowmwxjbahjfdtf5ap7b3gy
more »... produced viable floating cells at a rate of 2.7-3.2 × 10 3 cells/cm 2 per primary culture. When only the floating cells from one dish were harvested and replated in another dish, the number of cells was 2.8 × 10 4 cells/cm 2 (approximately half confluency) on culture day 7. The number of cells was half of that obtained by culturing only adherent cells (5 × 10 4 cells/cm 2 ). The floating and adherent cells showed similar proliferation and differentiation properties. The recovery of floating cells from the culture medium could provide an approximately 1.5-fold increase in cell number over conventional monolayer culture. Thus, the collection of floating cells may be regarded as a simple, easy, and reliable method to increase the cell harvest for chondrocytes.
Instead of the silicone implants previously used for repair and reconstruction of the auricle and nose lost due to accidents and disease, a new treatment method using tissue-engineered cartilage has been attracting attention. The quality of cultured cells is important in this method because it affects treatment outcomes. However, a marker of chondrocytes, particularly auricular chondrocytes, has not yet been established. The objective of this study was to establish an optimal marker to evaluatedoi:10.1089/biores.2019.0058 pmid:32140296 pmcid:PMC7057647 fatcat:27hg25fh5jhg7d7p5be2arkmnm
more »... the quality of cultured auricular chondrocytes as a cell source of regenerative cartilage tissue. Gene expression levels were comprehensively compared using the microarray method between human undifferentiated and dedifferentiated auricular chondrocytes to investigate a candidate quality control index with an expression level that is high in differentiated cells, but markedly decreases in dedifferentiated cells. We identified glial fibrillary acidic protein (GFAP) as a marker that decreased with serial passages in auricular chondrocytes. GFAP was not detected in articular chondrocytes, costal chondrocytes, or fibroblasts, which need to be distinguished from auricular chondrocytes in cell cultures. GFAP mRNA expression was observed in cultured auricular chondrocytes, and GFAP protein levels were also measured in the cell lysates and culture supernatants of these cells. However, GFAP levels detected from mRNA and protein in cell lysates were significantly decreased by increases in the incubation period. In contrast, the amount of protein in the cell supernatant was not affected by the incubation period. Furthermore, the protein level of GFAP in the supernatants of cultured cells correlated with the in vitro and in vivo production of the cartilage matrix by these cells. The productivity of the cartilage matrix in cultured auricular chondrocytes may be predicted by measuring GFAP protein levels in the culture supernatants of these cells. Thus, GFAP is regarded as a marker of the purity and properties of cultured auricular chondrocytes.
Steady and useful culture for chondrocytes is essential for cartilage regenerative medicine. However, in conventional plate culture, the chondrocytes become dedifferentiated and lose their ability to make cartilage matrices. Three-dimensional culture mimicking the physiological environment in native chondrocytes is useful to maintain the chondrocyte properties during the proliferation culture. However, the three-dimensional culture is practically a hard task due to difficult harvest of thedoi:10.4236/msa.2013.48a008 fatcat:7ir7caxvh5db7phk5fojg5alze
more »... . Thus, we attempted to apply porous materials, hollow fibers for the three-dimensional culture, and developed their module to realize the effective harvest of the cells. Polyethersulfone-based hollow fibers, whose safety and cell affinity were confirmed by the experiment of the coculture with human chondrocytes, were collected to fabricate a module. The hollow fiber module was installed with screw ends, and enabled the easy removal of chondrocytes from the inner unit. Cultured human chondrocytes embedded within collagen hydrogel were put into the outer lumen of the hollow fiber module, while chondrocyte prolfieration medium was perfused through the inner lumen at 0 to 30 mL/min. After 2 weeks' culture, the flow rate of 3 to 10 mL/min effectively supported the chondrocyte proliferation. Then, long-term culture using the hollow fiber module at flow rate of 5 mL/min was performed, revealing that the cell growth in this module at 3 weeks was approximately twice larger than that in static culture. The numbers of viable cells could be maintained by week 7. The hollow fiber module installed with screw ends can effectively culture and harvest the chondrocytes.
For regenerative medicine, clarification of in vivo migration of transplanted cells is an important task to secure the safety of transplanted tissue. We had prepared tissue-engineered cartilage consisting of cultured chondrocytes with collagen hydrogel and a biodegradable porous polymer, and we clinically applied it for treatment of craniofacial anomaly. To verify the safety of this tissue-engineered cartilage, we had syngenically transplanted the tissue-engineered cartilage using chondrocytesdoi:10.4236/ojrm.2013.24013 fatcat:65i7kd5yhjfgxilwx66zvz7nau
more »... arvested from EGFP-transgenic mice into subcutaneous pocket of wild type mice, and investigated localizations of transplanted chondrocytes in various organs including cerebrum, lung, liver, spleen, kidney, auricle, gastrocnemius, and femur. After 8 to 24 weeks of the transplantation, accumulation of cartilaginous matrices was observed in tissue-engineered cartilage, while EGFP-positive transplanted chondrocytes were localized in this area. Otherwise, no EGFP was immunohistochemically detected in each organ, suggesting that subcutaneously-transplanted chondrocytes do not migrate to other organs through the circulation. In cartilage tissue engineering using cultured chondrocytes, risk for migration and circulation of transplanted cells seemed negligible, and that ectopic growth of the cells was unlikely to occur, showing that this is safe technique with regard to the in vivo mi-gration of transplanted cells.
.,３ ３ １,８ ８ ９-８ ９ ５ (１ ９ ９ ４) . ３) Hoshi K. et al ., Oral Sci. ...doi:10.14894/faruawpsj.51.2_109 fatcat:klwxrw6y25chdgpaeguor5nmd4
Neutron/ Heavy ion/ RBE/ Drosophila/ Somatic mutation The relative biological effectiveness (RBE) of 252 Cf neutrons and synchrotron-generated high-energy charged particles for mutation induction was evaluated as a function of linear energy transfer (LET), using the loss of heterozygosity for wing-hair mutations and the reversion of the mutant white-ivory eye-color in Drosophila melanogaster. Loss of heterozygosity for wing-hair mutations results predominantly from mitotic crossing over induceddoi:10.1269/jrr.40.s106 pmid:10804999 fatcat:qjh3o23scjcrvgzi4nz7ndg35a
more »... in wing anlage cells of larvae, while the reverse mutation of eye-color is due to an intragenic structural change (2.96 kb-DNA excision) in the white locus on the X-chromosome. The measurements were performed in a combined mutation assay system so that induced mutant wing-hair clones as well as revertant eye-color clone can be detected simultaneously in the same individual. Larvae were irradiated at the age of 3 days post oviposition with 252 Cf neutrons, carbon beam or neon beam. For the neutron irradiation, the RBE values for wing-hair mutations were larger than that for eye-color mutation by about 7 fold. The RBE of carbon ions for producing the wing-hair mutations increased with increase in LET. The estimated RBE values were found to be in the range 2 to 6.5 for the wing-hair. For neon beam irradiation, the RBE values for wing-hair mutations peak near 150 keV/mm and decrease with further increase in LET. On the other hand, the RBE values for the induction of the eye-color mutation are nearly unity in 252 Cf neutrons and both ions throughout the LET range irradiated. We discuss the relationships between the initial DNA damage and LET in considering the mechanism of somatic mutation induction.
Functional near-infrared spectroscopy (fNIRS) signals originate in hemoglobin changes in both the superficial layer of the head and the brain. Under the assumption that the changes in the blood flow in the scalp are spatially homogeneous in the region of interest, a variety of methods for reducing the superficial signals has been proposed. To clarify the spatial distributions of the superficial signals, the superficial signals from the forehead during a verbal-fluency task were investigated bydoi:10.1117/1.jbo.21.6.066009 pmid:27297363 fatcat:uyf73hm7bzc6ff5qqnulacysou
more »... sing ten source-detector pairs separated by 5 mm, whereas fNIRS signals were also detected from two source-detector pairs separated by 30 mm. The fNIRS signals strongly correlated with the superficial signals at some channels on the forehead. Hierarchical cluster analysis was performed on the temporal cross-correlation coefficients for two channels of both the NIRS signals, and the analysis results demonstrate spatially heterogeneous distributions and network structures of the superficial signals from within the forehead. The results also show that the assumption stated above is invalid for homogeneous superficial signals from any region of interest of 15-mm diameter or larger on the forehead. They also suggest that the spatially heterogeneous distributions may be attributable to vascular networks, including supraorbital, supratrochlear, and superficial temporal vessels.
Nihon Kyukyu Igakukai Zasshi
The calculated risk of cancer in humans due to radiation exposure is based primarily on long-term follow-up studies, e.g. the life-span study (LSS) on atomic bomb (A-bomb) survivors in Hiroshima and Nagasaki. Since A-bomb radiation consists of a mixture of γ-rays and neutrons, it is essential that the relative biological effectiveness (RBE) of neutrons is adequately evaluated if a study is to serve as a reference for cancer risk. However, the relatively small neutron component hampered thedoi:10.1093/jrr/rrw079 pmid:27614201 pmcid:PMC5137296 fatcat:4h5esslgujdkvd26m4ieteetda
more »... t estimation of RBE in LSS data. To circumvent this problem, several strategies have been attempted, including dose-independent constant RBE, dose-dependent variable RBE, and dependence on the degrees of dominance of intermingled γ-rays. By surveying the available literature, we tested the chromosomal RBE of neutrons as the biological endpoint for its equivalence to the microdosimetric quantities obtained using a tissue-equivalent proportional counter (TEPC) in various neutron fields. The radiation weighting factor, or quality factor, Q n , of neutrons as expressed in terms of the energy dependence of the maximum RBE, RBE m , was consistent with that predicted by the TEPC data, indicating that the chromosomally measured RBE was independent of the magnitude of coexisting γ-rays. The obtained neutron RBE, which varied with neutron dose, was confirmed to be the most adequate RBE system in terms of agreement with the cancer incidence in A-bomb survivors, using chromosome aberrations as surrogate markers. With this RBE system, the cancer risk in A-bomb survivors as expressed in unit dose of reference radiation is equally compatible with Hiroshima and Nagasaki cities, and may be potentially applicable in other cases of human radiation exposure.
The bilateral ventrolateral prefrontal cortices (VLPFCs) are involved, through the amygdalae, in both the generation and regulation of unpleasant emotions Hoshi et al., 2011) . ... and 100 pictures from other photograph collections (Fuji Film Co., Tokyo, Japan) rated by 33 healthy volunteers (12 male, 21 female, 20-28 years old), none of which was a subject in the present study (Hoshi ...doi:10.3389/fnhum.2015.00051 pmid:25713527 pmcid:PMC4322640 fatcat:tezc57mdszefbhahsidwqj2mv4
Pluripotent stem cells have an advantage that they can proliferate without reduction of the quality, while they have risk of tumorigenesis. It is desirable that pluripotent stem cells can be utilized safely with minimal effort in cartilage regenerative medicine. To accomplish this, we examined the potential usefulness of induced pluripotent stem cells (iPS cells) after minimal treatment via cell isolation and hydrogel embedding for cartilage regeneration using a large animal model. Porcinedoi:10.1016/j.reth.2018.06.003 pmid:30525076 pmcid:PMC6222263 fatcat:krxbpsctp5g2tasitdby4n7iw4
more »... ike cells were established from the CLAWN miniature pig. In vitro differentiation was examined for porcine iPS-like cells with minimal treatment. For the osteochondral replacement model, osteochondral defect was made in the quarters of the anteromedial sides of the proximal tibias in pigs. Porcine iPS-like cells and human iPS cells with minimal treatment were seeded on scaffold made of thermo-compression-bonded beta-TCP and poly-L-lactic acid and transplanted to the defect, and cartilage regeneration and tumorigenesis were evaluated. The in vitro analysis indicated that the minimal treatment was sufficient to weaken the pluripotency of the porcine iPS-like cells, while chondrogenic differentiation did not occur in vitro. When porcine iPS-like cells were transplanted into osteochondral replacement model after minimal treatment in vitro, cartilage regeneration was observed without tumor formation. Additionally, fluorescent in situ hybridization (FISH) indicated that the chondrocytes in the regenerative cartilage originated from transplanted porcine iPS-like cells. Transplantation of human iPS cells also showed the regeneration of cartilage in miniature pigs under immunosuppressive treatment. Minimally-treated iPS cells will be a useful cell source for cartilage regenerative medicine.
Semipalatinsk / Nuclear tests /TLD / Brick / External dose Accumulated external radiation doses of residents near the Semipalatinsk nuclear test site of the former USSR are presented as a results of study by the thermoluminescence technique for bricks sampled at several settlements in 1995 and 1996. The external doses that we evaluated from exposed bricks were up to about 100 cGy for resident. The external doses at several points in the center of Semipalatinsk City ranged from a backgrounddoi:10.1269/jrr.40.337 pmid:10748579 fatcat:z3jjr3kzhfhgpii4hxx77skhxm
more »... to 60 cGy, which was remarkably high compared with the previously reported values based on military data.
We have investigated the effects of In doping on the optical properties of GaN films grown by gas-source molecular-beam epitaxy. Time-resolved photoluminescence was carried out to study the transient optical properties of the epitaxial films. In comparison to the undoped GaN film, the spontaneous emission lifetime was prolonged from below 20 to 70 ps by doping with In. Under high-excitation density, stimulated emission was observed from both samples. The threshold excitation density was founddoi:10.1063/1.125178 fatcat:4zceco7zejfubj3jjo3cxraxvi
more »... be reduced in the In-doped sample. These significant improvements of the optical properties are attributed to the effective suppression of the formation of the nonradiative recombination centers caused by a change of the growth kinetics induced by a small amount of In supplied during growth of the GaN films. GaN and related III-V nitride materials have recently drawn a great deal of attention mainly because of their possible applications in light emitting devices operating in the green, blue, and ultraviolet wavelength regions. InGaN ternary alloys are widely used as the active layer for practical devices such as blue/green light-emitting diodes 1 and violet laser diodes. 2 A further extension to shorter wavelength requires the GaN or AlGaN as active layers. However, devices realized with these active layers are rare, partly because materials with wide band gaps energy easily suffer from the formation of nonradiative recombination centers which may lead to a deterioration in luminescence efficiency. A solution to this problem may be to use a surfactant. 3 Surfactants are expected to modify the kinetics of epitaxial growth, therefore choosing the adequate surfactant could result in the improvement of crystal quality by controlling the surface diffusion length of the adatoms. Recently, some experimental reports on In surfactant effects investigated from a viewpoint of optical, 4-6 electrical, 6 and growth properties 7 have been published. All those studies showed positive effects of In, supplied on the surfaces during growth, to improve the crystal quality of GaN. In this study, we demonstrate the effect of In doping on the improvement of crystal quality by performing timeresolved photoluminescence ͑TRPL͒ spectroscopy. Because the carrier lifetime reflects the concentration of recombination centers directly, this investigation method provided us with a sensitive probe for detection of nonradiative recombination centers. The excitation density was chosen in the range where the corresponding photogenerated carrier density was around and above the Mott density. This allowed us to explore the optical properties under a high carrier density similar to what is found in commercial devices operating under high carrier injection. In-doped GaN films as well as undoped films ͑both approximately 0.4 m thick͒ were prepared by gas-source molecular-beam epitaxy ͑GS-MBE͒ on low-temperature grown GaN buffer/Al 2 O 3 substrate. Details about the growth procedure can be found in Ref. 4. Both samples have n-type conductivity with an electron concentration of 10 18 -10 19 cm Ϫ3 at room temperature. 6 From the absence of energy shift of the band edge-related PL emission, the In incorporation was estimated to be less than 0.1%. 4,6 To study the steady-state PL properties, PL measurement excited by a He-Cd ͑325 nm͒ laser at 14 K was carried out and spectra were shown in the lower part of Figs. 1͑a͒ and 1͑b͒. The peak at 3.47 eV which is attributed to the neutral donor bound exciton (I 2 ) 8 was observed for both samples but the PL emissions related to the impurity or structural defects ͑3.43 eV͒ and the donor to acceptor pair emission ͑3.32 eV͒ were decreased or absent in the In-doped GaN films. Furthermore, the intensity of the I 2 emission was enhanced about 60 times by the In doping. These features are attributed to a reduction of the impurity incorporation and/or a reduced formation of defects due to a modification of the growth kinetics induced by an In supply during growth. To further investigate the effects of In doping, femtosecond TRPL experiments were performed using a Spectra-Physics mode-locked Ti:sapphire laser followed by a regenerative amplifier ͑REGEN͒ operating at 1 kHz. The REGEN was seeded by a mode-locked 80 fs/800 nm laser pulse. The output of the REGEN had a photon energy of 1.55 eV, and was sent to an optical parametric amplifier. An excitation pulse ͑3.79 eV͒ with a pulse duration of about 200 fs was obtained after a parametric amplification and a fourth harmonic generation process. The spot diameter of the excitation pulse on the sample surface was estimated to be 200 m. Photon counting with a high-speed single-scan streak camera ͑Hamamatsu C5680͒ was used to detect the luminescence. The overall time resolution including the laser pulse width and the temporal spread within the monochromator was Ͻ20 ps. All the TRPL spectra were detected at 8 K vertical to the epilayer surface. Solid lines in Fig. 2 show the time decay profiles of both a͒ Electronic
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