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Y Yoshimura

Publications and source records attributed to Y Yoshimura.

At least 19 recordsLinked to original sources
PubMed2006

Experimental signature of medium modifications for rho and omega mesons in the 12 GeV p+A reactions.

The invariant mass spectra of e+e- pairs produced in 12 GeV proton-induced nuclear reactions are measured at the KEK Proton Synchrotron. On the low-mass side of the meson peak, a significant enhancement over the known hadronic sources has been observed. The mass spectra, including the excess, are well reproduced by a model that takes into account the density dependence of the vector meson mass modification, as theoretically predicted.

Journal Article↗
PubMed2006

Continuous assay of protein tyrosine phosphatases based on fluorescence resonance energy transfer.

An assay method that continuously measures the protein tyrosine phosphatase (PTP)-catalyzed dephosphorylation reaction based on fluorescence resonance energy transfer (FRET) was developed as an improvement of our previously reported discontinuous version [M. Nishikata, K. Suzuki, Y. Yoshimura, Y. Deyama, A. Matsumoto, Biochem. J. 343 (1999) 385-391]. The assay uses oligopeptide substrates that contain (7-methoxycoumarin-4-yl)acetyl (Mca) group as a fluorescence donor and 2,4-dinitrophenyl (DNP) group as a fluorescence acceptor, in addition to a phosphotyrosine residue located between these two groups. In the assay, a PTP solution is added to a buffer solution containing a FRET substrate and chymotrypsin. The PTP-catalyzed dephosphorylation of the substrate and subsequent chymotryptic cleavage of the dephosphorylated substrate results in a disruption of FRET, thereby increasing Mca fluorescence. In this study, we used FRET substrates that are much more susceptible to chymotryptic cleavage after dephosphorylation than the substrate used in our discontinuous assay, thus enabling the continuous assay without significant PTP inactivation by chymotrypsin. The rate of fluorescence increase strictly reflected the rate of dephosphorylation at appropriate chymotrypsin concentrations. Since the continuous assay allows the measurement of initial rate of dephosphorylation reaction, kinetic parameters for the dephosphorylation reactions of FRET substrates by Yersinia, T-cell and LAR PTPs were determined. The continuous assay was compatible with the measurement of very low PTP activity in a crude enzyme preparation and was comparable in sensitivity to assays that use radiolabeled substrates.

3T3 Cells↗
PubMed2005

Microvascular distribution and vascular endothelial growth factor expression in bovine cystic follicles.

The aim of this study was to examine the distribution of microvessels in the theca and the expression of vascular endothelial growth factor (VEGF) in the theca and granulosa of cystic follicles. Paraffin sections of cystic follicles were stained with Bandeiraea simplicifolia-I (BS-I) to visualize the endothelial cells of microvessels. The other sections were immunostained with anti-VEGF antibody. The mRNA expression of VEGF in the theca interna of cystic and healthy follicle was determined by RT-PCR. In the theca interna, cystic follicles with granulosa cells had significantly greater microvessel number density (the number of microvessels per given field) and area (area occupied by microvessels per given area) than healthy follicles in various sizes (<3, 4-8, >9 mm). Loss of granulosa cells from cystic follicles resulted in a similar number density, but significantly smaller area of microvessels in the theca interna. There was no significant difference in the microvessel number density and area of the theca externa between the types of follicle. VEGF protein was expressed in the granulosa and theca interna of healthy and cystic follicles. These results demonstrate that cystic follicles have a highly developed vasculature network in the theca interna, especially in cystic follicles containing granulosa cells. It is also suggested that VEGF is highly expressed in the cystic follicle as well as healthy follicle, which may be associated with advanced vasculature and the accumulation of follicular fluid in cystic follicles.

Animals↗
PubMed2005

Fetal jaw movement affects condylar cartilage development.

Using a mouse exo utero system to examine the effects of fetal jaw movement on the development of condylar cartilage, we assessed the effects of restraint of the animals' mouths from opening, by suture, at embryonic day (E)15.5. We hypothesized that pre-natal jaw movement is an important mechanical factor in endochondral bone formation of the mandibular condyle. Condylar cartilage was reduced in size, and the bone-cartilage margin was ill-defined in the sutured group at E18.5. Volume, total number of cells, and number of 5-bromo-2'-deoxyuridine-positive cells in the mesenchymal zone were lower in the sutured group than in the non-sutured group at E16.5 and E18.5. Hypertrophic chondrocytes were larger, whereas fewer apoptotic chondrocytes and osteoclasts were observed in the hypertrophic zone in the sutured group at E18.5. Analysis of our data revealed that restricted fetal TMJ movement influences the process of endochondral bone formation of condylar cartilage.

Animals↗
PubMed2004

Identification of zonal flows in a toroidal plasma.

This Letter presents experimental confirmation of the presence of zonal flows in magnetically confined toroidal plasma using an advanced diagnostic system--dual heavy ion beam probes. The simultaneous observation of an electric field at two distant toroidal locations (approximately 1.5 m apart) in the high temperature (approximately 1 keV) plasma provides a fluctuation spectrum of electric field (or flow), a spatiotemporal structure of the zonal flows (characteristic radial length of approximately 1.5 cm and lifetime of approximately 1.5 ms), their long-range correlation with toroidal symmetry (n=0), and the difference in the zonal flow amplitude with and without a transport barrier. These constitute essential elements of turbulence-zonal flow systems, and illustrate one of the fundamental processes of structure formation in nature.

Journal Article↗
PubMed2004

Improved measurement of the K+-->pi+nunu; branching ratio.

An additional event near the upper kinematic limit for K+-->pi(+)nunu; has been observed by experiment E949 at Brookhaven National Laboratory. Combining previously reported and new data, the branching ratio is B(K+-->pi(+)nunu;)=(1.47(+1.30)(-0.89))x10(-10) based on three events observed in the pion momentum region 211<P<229 MeV/c. At the measured central value of the branching ratio, the additional event had a signal-to-background ratio of 0.9.

Journal Article↗
PubMed2004

Changes in the responsiveness of hen anterior pituitary to cLHRH-II during induced molting.

The goal of this study was to determine whether the responsiveness of the anterior pituitary to cLHRH-II in relation to luteinizing hormone-beta subunit (LHbeta) mRNA expression is improved by induced molting. White Leghorn hens were subjected to induced molting by feed withdrawal for 4 days. The anterior pituitaries were collected from hens of pretreatment (PT), 1 day after resumption of feeding (1DRF) and on the day of resumption of laying (RL). They were processed for organ culture in the medium with or without cLHRH-II, followed by reverse transcription and competitive PCR. When pituitary tissues were incubated without cLHRH-II, the expression of LHbeta mRNA did not show any significant difference between PT and RL group hens. In contrast, the expression of LHbeta mRNA in the pituitaries that were incubated with cLHRH-II was significantly greater in RL group hens than those in PT and 1DRF groups. Among PT, 1DRF, and RL groups only RL hens showed significant increase of LHbeta mRNA synthesis when compared with control (without cLHRH-II). These results suggest that the responsiveness of the anterior pituitary to cLHRH-II increased in postmolt hens, indicating that the functions of this organ might be improved by induced molting.

Animals↗
PubMed2004

Molecular and morphological differentiation between the crop and weedy types in velvetleaf (Abutilon theophrasti Medik.) using a chloroplast DNA marker: seed source of the present invasive velvetleaf in Japan.

A comparison of chloroplast DNA (cpDNA) sequences was carried out between the crop and weed types of Abutilon theophrasti to clarify the seed source of the present weedy velvetleaf in Japan. A sequencing analysis of approx. 6% of the chloroplast genome (ca 10 kbp) detected three nucleotide substitutions, one six-base-pair insertion/deletion (indel) and one 30-base pair inversion, which distinguish two haplotypes of cpDNA. A PCR-based survey of the indel and the inversion revealed that the 93 accessions of velvetleaf collected from the world could be divided into two groups. A morphological marker (capsule color) could be used to discriminate the crop type and the weed type, and hence, along with cpDNA haplotype, to distinguish three genotypes (Type I, II, and III). All Japanese cultivars and crop accessions from other countries were Type I. Weed types were divided into Type II and III. All of the samples from the USA, and the samples taken from grain imports to Japan were Type III. Since most of the weedy types distributed in Japan were of Type III, it is argued that they were introduced as seeds in the imported grain. We also found that the Type II plants sporadically occurred in Japan. It is suggested that they originated as hybrids, with indigenous cultivars as the maternal ancestor. Such hybrids must have survived since the cessation of velvetleaf cultivation about a century ago.

Chloroplasts↗
PubMed2004

Ovarian cell-mediated immune response to Salmonella enteritidis infection in laying hens (Gallus domesticus).

The aim of this study was to examine the response of cell-mediated ovarian immunity against Salmonella infection in hens. Laying hens were injected intraperitoneally with PBS (control) or Salmonella enteritidis (SE). Ovarian stroma containing stromal follicles, small white follicles (SWF), and third largest (F3) and the largest (F1) follicles were collected 12 or 24 h after inoculation and fixed in periodate-lysine-paraformaldehyde. Frozen sections were stained first for CD3+, CD4+, or CD8+ T cells and then for SE by a double immunostaining method. Immunoreaction products for SE were detected in the ovarian stroma, theca of stromal follicles, SWF, F3, and F1 at 12 and 24 h after inoculation. Immunopositive T-cell subsets were localized in the stroma and theca of follicles in birds inoculated with or without SE. The populations of CD3+, CD4+, and CD8+ T cells were significantly greater in the stroma and the theca of follicles 12 h after SE inoculation than in those of control birds (P < 0.01). Their frequencies were further increased in those tissues 24 h after inoculation (P < 0.01). Injection of SE did not cause significant differences in the CD4+:CD8+ T-cell ratio as both subsets increased proportionately. The current results indicate that the population of T-cell subsets increases in the ovarian stroma and the follicular tissues in response to SE invasion within 12 h of inoculation. Thus, cell-mediated immune response against SE, their products, or both may be induced in the hen ovary.

Animals↗
PubMed2003

Sawtooth oscillation in current-carrying plasma in the large helical device.

Sawtooth oscillations have been observed in current-carrying helical plasmas by using electron-cyclotron-emission diagnostics in the Large Helical Device. The plasma current, which is driven by neutral beam injection, reduces the beta threshold of the sawtooth oscillation. When the central q value is increased due to the plasma current, the core region crashes, and, when it is decreased, the edge region crashes annularly. Observed rapid mixture of the plasma in the limited region suggests that these sawtooth crashes are reconnection phenomena. Unlike previous experiments, no precursor oscillation has been observed.

Journal Article↗
PubMed2003

Changes in the expression of TGFbeta-isoforms in the anterior pituitary during withdrawal and resumption of feeding in hens.

Our goal was to determine whether TGFbeta-isoforms were involved in the remodeling of the pituitary cell population which occurred by regulation of feeding. The current study examined whether TGFbeta-isoforms were produced in the anterior pituitary, and the mRNA expression of TGFbeta-isoforms changed during withdrawal and resumption of feeding. White Leghorn laying hens were subjected to feed withdrawal for 4 days with a resumption of feeding thereafter. The anterior pituitary tissues were collected from hens of pretreatment (PT), 3 days after feed withdrawal (3DFW), 1 and 5 days after the resumption of feeding (1DRF and 5DRF, respectively), and on the day of resumption of egg-laying (RL). They were processed for semi-quantification of TGFbeta2, beta3, and beta4 mRNA expressions by reverse transcription-polymerase chain reaction (RT-PCR) and for immunocytochemistry for TGFbeta3. TGFbeta2, TGFbeta3, and TGFbeta4 mRNA expression with a product size of 269, 236, and 163bp, respectively, was observed in the anterior pituitaries in all groups of hens. Although the expression of TGFbeta2 and TGFbeta4 mRNA did not show any significant change, that of TGFbeta3 mRNA significantly declined in the 1DRF hens and recovered by the resumption of laying. Immunostaining revealed that TGFbeta3 was located in the cytoplasm of glandular cells with granule forms in all groups of hens. The ovarian and oviductal weights sharply declined in the 3DFW and 1DRF groups, followed by a full recovery in the RL hens. These results indicate that TGFbeta2, beta3, and beta4 were expressed in the chicken anterior pituitary, and TGFbeta3 mRNA expression was changed in correlation with the regulation of feeding, suggesting that this isoform may play a significant role in the regulation of the glandular cell population and/or differentiation.

Animal Feed↗
PubMed2003

Distribution of cytochrome P450-side chain cleavage in the theca interna layers of bovine small antral and cystic follicles.

Cystic follicle is anovulatory follicular structure that is caused by an endocrine imbalance. The activity of cytochrome P450-side chain cleavage (P450scc) is essential for the initiation of steroidogenesis in the follicle. The present study was designed to compare the frequency of cells containing P450scc between healthy and atretic small antral follicles, and among several types (I, II and III, classified based on the presence of granulosa layer) of cystic follicles. Paraffin sections of healthy (2-5 mm in diameter), atretic (2-5 mm) and cystic follicles (>25 mm) were immunohistochemically stained with rabbit polyclonal antibody to bovine P450scc. The P450scc-positive cells were counted in four different regions of the follicles from the apical to the basal side. In small antral follicles and cystic follicles, P450scc-positive cells were localized in the theca interna layers but not granulosa layers. The P450scc-positive cell populations decreased in the late atretic follicles compared with the early and advanced atretic follicles at all the regions of follicle. Type III cystic follicles showed significantly lower frequencies of P450scc-positive cells than those in the types I and II cystic follicles. These results suggest that in both small and cystic follicles in cows, total loss of granulosa cells may be associated with the reduction of frequency of P450scc-positive cells in theca interna layer.

Animals↗
PubMed2003

Changes in the population of pituitary protein transcription factor-1 nuclei in the anterior pituitary during withdrawal and resumption of feeding in hens.

Pituitary protein transcription factor (Pit-1) is a member of a large family of protein transcription factors that include Pit-1, Oct-1, Oct-2, and Unc-86. The goal of this experiment was to determine whether the population of Pit-1-containing cells changes in the anterior pituitary of chicken by the regulation of feeding. White Leghorn hens were subjected to withdrawal and resumption of feeding. The anterior pituitaries were collected from hens at pretreatment, at 2 d after withdrawal of feeding (2DWF), and 1 d and 5 d after resumption of feeding (1DRF and 5DRF, respectively). Sections of the pituitaries were immunostained for Pit-1. They were examined under a light microscope with an image analysis computer system. The Pit-1 positive nuclei were found in the glandular cells in the cephalic and caudal lobes of the anterior pituitary in all four groups of hens. The Pit-1 cell population significantly increased in the 2DWF and 1DRF and decreased thereafter in 5DRF. These results suggests that feed withdrawal may stimulate Pit-1 expression in chicken, suggesting that Pit-1 may be involved in control of pituitary functions during the process of feed regulation.

Animals↗
PubMed2003

Invasion of Salmonella enteritidis in the tissues of reproductive organs in laying Japanese quail: an immunocytochemical study.

The aim of this study was to determine whether Salmonella enteritidis (SE) inoculated into the peritoneal cavity would colonize tissues of reproductive organs in Japanese quail hens. Quail hens regularly laying were intraperitoneally inoculated with 5 x 10(7) or 5 x 10(8) SE cells, and the ovary, oviduct, kidney, spleen, liver, and large intestine were excised 24 or 48 h after the treatment. Paraffin sections of these organs were immunostained for SE. Invasion of SE was found in the tissues of the ovarian stroma, the follicular wall including superficial and theca layers, and occasionally in the granulosa layer and yolk. The SE immunoreaction product frequently was found in the fibroblast-like and macrophage-like cells in the stroma and surface layer of follicles. The SE immunoreaction products were identified on the mucosal surface, in the mucosal epithelium, and in the stromal tissues in all segments of the oviduct. Many of the bacteria were contained in the cytoplasm of mucosal epithelial cells and stromal cells in those tissues. The SE immunoreactions were also found in the tissues of kidney, spleen, and liver and in the large intestine. These results suggest that SE organisms introduced into the peritoneal cavity can invade and colonize the tissues of ovary and oviduct and may be responsible in the production of contaminated eggs.

Animals↗
PubMed2003

Direct phosphorylation of histamine H1 receptor by various protein kinases in vitro.

Phosphorylation of G protein-coupled receptors (GPCRs) by various kinases is suggested to be an important step in initiating receptor desensitization. Some reports have indirectly demonstrated the involvement of protein kinase C (PKC)-mediated receptor phosphorylation in the desensitization of the histamine H1 receptor (H1R). In this study, human c-myc-epitope-tagged H1R (hm mcH1R) was expressed in Sf9 cells, and an in vitro approach was taken to obtain direct evidence that H1R could be phosphorylated by various kinases. When hm mcH1R, which had been immunoprecipitated with anti-c-myc antibody from Sf9 cell membranes, was incubated with PKC, cAMP-dependent protein kinase (PKA), calcium/calmodulin-dependent protein kinase II (CaMKII) or cGMP-dependent protein kinase (PKG), the immunoprecipitated receptor was phosphorylated by these kinases. Membrane-bound hm mcH1R, whose conformation is closer to its physiological state than that of the immunoprecipitated receptor, was also phosphorylated by PKC, PKA, CaMKII and PKG. Phosphorylation of immunoprecipitated and membrane-bound hm mcH1R was inhibited by kinase inhibitors. These data are the first demonstration of the phosphorylation of H1R by four protein kinases, i.e., PKC, PKA, CaMKII and PKG, and provide fundamental information to help us further understand the relationship between H1R phosphorylation and desensitization of this receptor.

Animals↗
PubMed2003

Expression of the exocytotic protein syntaxin in mouse oocytes.

Syntaxin is an integral membrane protein that is involved in membrane fusion. The exocytosis of the contents of cortical granules, secretory vesicles located in the cortex of an egg, modify the extracellular environment to block additional spermatozoa from penetrating the newly fertilized egg. The aim of this study was to characterize syntaxin expression in mouse oocytes, and to determine the specific isoform that is expressed. Syntaxin was demonstrated in the mouse ovary and in mouse oocytes by both western blot and reverse transcription-polymerase chain reaction analyses. Syntaxin 4 was specifically expressed in metaphase II oocytes. Syntaxin was also immunolocalized within metaphase II oocytes and one-cell embryos with pronuclei using laser scanning confocal microscopy. In metaphase II oocytes, syntaxin was located on the plasma membrane and in the cortex, where cortical granules are present, but was not seen at sites free of cortical granules. In one-cell embryos, no cytoplasmic region was free of syntaxin immunoreactivity. Immunoelectron microscopy detected syntaxin on both the plasma membrane and the vesicle membranes in mouse metaphase II oocytes. In conclusion the results indicate that syntaxin 4 co-localizes with cortical granules and participates in membrane fusion and exocytosis during the cortical reaction.

Animals↗
PubMed2003

Reliability and gender differences of static explosive grip parameters based on force-time curves.

AIM: The purpose of this study was to examine the reliability and gender differences of static explosive grip (SEG) parameters based on force-time curves. METHODS EXPERIMENTAL DESIGN: data were collected from 2 trials of SEG tests on the same day and 2 trials 1 week later. PARTICIPANTS: 50 healthy young males (21.2+/-1.57 yrs) and females (20.1+/-1.18 yrs) participated in this study. MEASURES: 12 variables based on factors such as time-course of force, average force, integrated area, maximal rate of force development, the product of force and inclination and exponential function of force development (EXP-M) were selected as force-time parameters in SEG testing. RESULTS: A significant reliability was obtained for all force-time parameters except the time to 90% of maximal grip strength (MAX), with the reliability of integrated area, average force, maximal rate of force development (DFmax), and the product of force and inclination being particularly high (ICC=0.633-0.930 for the same day, ICC=0.612-0.828 for different days). There were gender differences for all parameters except the time to MAX and EXP-M (p<0.05). In addition, many of the correlation coefficients between parameters were high, particularly for males. The average force, integrated area for 1 sec, and the product of force and inclination during the developmental phase significantly correlated with MAX in both males and females. The ratio between males and females in these force-time parameters was smaller than that of MAX (71.3%). CONCLUSION: It is considered that these parameters are dependent on the speed of muscle contraction. These results suggest that the evaluation parameters, such as average force, integrated area, the product of force and inclination, and maximal rate of force development are useful for evaluating static explosive grip.

Adult↗