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ABSTRACT: We investigated the electrical transport properties in Co<sub>2</sub>FeAl<sub>0.5</sub>Si<sub>0.5</sub> (CFAS)/GaAs junctions. From current density-voltage characteristics, the formation of a Schottky tunnel barrier in the CFAS/GaAs interface was indicated. Moreover, junction resistance of 2×10<sup>-9</sup> Ω·m<sup>2</sup> which is adequate for high magnetoresistance ratio attributable to high spin injection efficiency was obtained. Comparing the bias dependencies of conductance with samples, which CFAS ordering is lower, indicated that L 2<sub>1</sub> ordered CFAS contributes to electrical transport. Finally, the spin injection signal was observed with 3-terminal Hanle measurement, and spin relaxation time was estimated to be 380 ps at 5 K.
IEEE Transactions on Magnetics 11/2011; · 1.36 Impact Factor
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ABSTRACT: A multi-step word-line control technology (MWC), combined with a new hierarchical cell SRAM architecture (HCA), has been developed to overcome rapid increase in random variability with no area penalty. A 40-nm-node 0.248-μm<sup>2</sup>-cell SRAM using a single power supply has been successfully fabricated, pushing up bit density to 2.98 Mb/mm<sup>2</sup>. MWC improved VDD_min@-6σ by 0.34 V and 0.22 V for read and write operations, respectively, enabling stable 1.0 V operations. Four nanosecond SRAM access time is achieved by adopting HCA, which cancels out a 1.4 ns increase of access delay caused by MWC.
IEEE Journal of Solid-State Circuits 05/2011; · 3.23 Impact Factor
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ABSTRACT: Polycrystalline Pd/SnO<sub>2</sub> nanowires have been fabricated using ZnO-nanowire templates by the combination of thermal evaporation, pulsed-laser deposition, and dc sputtering. The rutile SnO<sub>2</sub> nanocrystals were grown on the ZnO nanowire with Volmer-Weber mode due to the large lattice mismatch. The discrete Pd nanocrystals were also successfully deposited onto the nanostructures, which were identified by high-angle annual dark field scanning transmission electron microscopy. The 1-D polycrystalline SnO<sub>2</sub> coatings with catalytically active Pd layer can effectively detect air-diluted H<sub>2</sub>S. The sensing behaviors can be understood by a Langmuir isotherm absorption model. The fabrication method provides a general strategy to prepare 1-D metal-oxide conductometric gas sensors.
IEEE Transactions on Nanotechnology 10/2010; · 2.29 Impact Factor
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ABSTRACT: This paper presents the study about the dynamics in the folding of long DNA under strong flow. Direct observation of the folding process of the tethered DNA molecule induced by adding a condensing agent is demonstrated using a microfluidic device, and this theoretical interpretation of the process is provided. From the direct observation, it is found that the folding dynamics typically exhibits characteristic three stages: (i) initial rapid compaction, (ii) slowing-down, (iii) sudden speed-up. Such a notable feature pin-points a nonequilibrium flow effect and can be interpreted by a simple theory, which takes account of the nonuniformity of the tethered chain stretched by flow.
Micro-NanoMechatronics and Human Science, 2008. MHS 2008. International Symposium on; 12/2008
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ABSTRACT: Some examples of novel rain attenuation mitigation technologies for future high-speed satellite communication or broadcasting systems using Ka-band radio wave or above bands such as Q-, V- and W-bands are proposed. As regards adaptive satellite power control and time diversity methods, effects of those methods are shown quantitatively. In these analyses rainfall rate data in Japan and Indonesia, and slant-path attenuation data at 19.5 GHz measured for over 8 years in Japan are used Importance of spatiotemporal properties of rainfall rate such as time- and space-correlation is mentioned for quantitative analysis of the effects of future powerful attenuation mitigation technologies.
Information, Communications & Signal Processing, 2007 6th International Conference on; 01/2008
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ABSTRACT: Spatial correlation property of rainfall rate in all over Japan is analysed by using data produced from Japanese Meteorological Agency called AMeDAS system. This property will become very useful for evaluating future powerful rain-induced attenuation mitigation methods such as multi-site site-diversity and adaptive transmit power control from HAPS or satellite. Several dependences of spatial correlation, such as distance, seasonal, integration-time and directional dependences are shown. In some area we find anisotropic feature of correlation property. Some examples of utilization of this spatial correlation property for evaluating some attenuation countermeasure methods are introduced.
Antennas and Propagation, 2007. EuCAP 2007. The Second European Conference on; 12/2007
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ABSTRACT: In the present study, we investigated the existence of soluble CD44 (sCD44) in human follicular fluid, the relationship between the concentration of sCD44 and that of other hormonal parameters, and the prognostic value of sCD44 in follicular fluid in in vitro fertilization (IVF) programs.
A total of 63 follicular fluid specimens from patients (n = 30) participating in our IVF programs was analyzed by RIA and enzyme-linked immunosorbent assay (ELISA).
The mean concentration (+/- SE) of sCD44 in follicular fluid was 265.4 +/- 7.8 ng/ml. The variation of the follicular fluid concentration of sCD44 was strictly associated with that of human chorionic gonadotropin (hCG) (r = 0.572, P < 0.0001). The mean concentration of sCD44 in follicular fluid was significantly higher in follicles containing subsequently unfertilized oocytes than that in those containing oocytes that had undergone fertilization (P = 0.0428). In the analysis of each follicle that contained an oocyte subsequently fertilized, the mean concentration of sCD44 was significantly higher in follicular fluid with the subsequently good-quality embryos than in that with the subsequently poor-quality embryos (P < 0.05).
These results indicated that the concentration of sCD44 in follicular fluid reflects the development of embryos derived from the same follicle, so the sCD44 in human follicular fluid may be useful in the assessment of the prognostic value of IVF programs.
Journal of Assisted Reproduction and Genetics 01/2001; 18(1):21-5. · 1.84 Impact Factor
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ABSTRACT: To determine the concentrations of hyaluronan, E(2), and progesterone in follicular fluids (FFs) and the incidence of apoptotic granulosa cells. Also, to examine the relationship between the concentration of hyaluronan and follicular steroids, the incidence of apoptotic cells, and the fertilizability of the oocyte in the same follicle.
Samples of 130 follicles were retrospectively analyzed for hyaluronan and steroids and the incidence of apoptotic cells.
The reproductive center in Yamagata University Hospital.
Forty women infertile because of tubal damage or unknown causes undergoing IVF treatment were selected.
The samples were collected from follicle aspirations.
The concentrations of hyaluronan and steroids in FFs, the incidence of apoptotic granulosa cells, and oocyte fertilizability.
The levels of hyaluronan in FF were found to correlate positively with P (r=0.444, P<0.0001) and the incidence of apoptotic cumulus granulosa cells (r=0.387, P=0.002) and inversely with E(2) (r = -0.601, P<0.0001) and free T (r = -0.344, P=0.001). The concentration of hyaluronan in FFs containing a subsequently fertilized oocyte after insemination was significantly lower than that in FFs containing a subsequently unfertilized oocyte (P=0.0005) (fertilized, 50.0 +/- 2.6 ng/mL; triploidy, 59.1 +/- 6.8; and unfertilized, 66.9 +/- 5.9).
The concentration of hyaluronan in FF is an indicator for estimation of oocyte viability for fertilization.
Fertility and Sterility 12/2000; 74(6):1148-52. · 3.56 Impact Factor
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ABSTRACT: The aim was to investigate which ovarian hyperstimulation protocol performed in the same patients causes development of oocytes of good quality.
Twenty normo-ovulatory women underwent three different controlled ovarian hyperstimulation protocols for in vitro fertilization-embryo transfer. Patients underwent follicle aspiration after administration of human chorionic gonadotropin (hCG). The total number of retrieved oocytes, the number of mature oocytes, and the rate of mature oocytes were examined. Recovered granulosa cells were stained with Hoechst 33258 and examined by fluorescence microscopy to estimate the incidence of apoptotic cells.
The total number of oocytes and the number of mature oocytes in gonadotropin-releasing hormone agonist (GnRHa) + human menopausal gonadotropin (hMG) + hCG and hMG + hCG cycles were higher than those in the natural cycle (P < 0.0001). The rate of mature oocytes in hMG + hCG cycle was the highest among the three protocols (P < 0.04). In the mural granulosa cells, the incidence of apoptotic cells in the GnRHa + hMG + hCG cycle was significantly higher than those of the natural (P < 0.002) and hMG + hCG cycles (P = 0.0002). The incidence of apoptotic cumulus granulosa cells in the GnRHa + hMG + hCG cycle was significantly higher than those of natural and hMG + hCG cycles (P < 0.002). Moreover, the incidence of apoptotic cumulus granulosa cells in the hMG + hCG cycle was significantly lower than that in the natural cycle (P < 0.01).
These results indicated that hMG + hCG is the most appropriate controlled ovarian hyperstimulation protocol among the three examined with regard to oocyte quality.
Journal of Assisted Reproduction and Genetics 11/2000; 17(10):580-5. · 1.84 Impact Factor
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ABSTRACT: The objective was to determine the effects of women's age on the ovarian fecundity as assessed by the incidence of apoptotic granulosa cells.
Twenty-eight normo-ovulatory women underwent ovulation induction for standard IVF. The husbands of these women showed severe male infertility factors. The women were divided into four groups according to their ages. Women underwent follicle aspiration after the administration of human menopausal gonadotropin plus human chorionic gonadotropin. The nuclei of granulosa cells were examined by using fluorescence microscopy, and the incidence of apoptotic granulosa cells was tabulated.
Granulosa cells in the older women revealed a significant increase in the number of apoptotic cells. The number of total oocytes and the number of mature oocytes obtained significantly decreased with age. However, endometrial thickness and follicular estradiol, progesterone, and free testosterone levels were not significantly different among four different age groups.
Age increases apoptotic changes in granulosa cells and consequently decreases the ovarian fecundity.
Journal of Assisted Reproduction and Genetics 04/2000; 17(3):168-73. · 1.84 Impact Factor
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ABSTRACT: OBJECTIVE: To determine the relation between the insemination method used and the quality of oocytes and embryos. DESIGN: Prospective study. SETTING: Assisted reproductive centers at Yamagata University Hospital and Kuramoto Women's Clinic in Yamagata, Japan. PATIENT(s): Forty patients undergoing IVF and 40 patients undergoing intracytoplasmic sperm injection (ICSI). INTERVENTION(s): To estimate oocyte quality, the granulosa cells surrounding the oocyte were fixed and stained with a commercial dye in both groups of patients. One thousand granulosa cells were examined under a fluorescence microscope. MAIN OUTCOME MEASURE(s): The incidence of apoptotic granulosa cells surrounding each oocyte. RESULT(s): The incidence of apoptosis in the granulosa cells enclosing the oocytes that were fertilized by IVF was significantly lower than that in the oocytes that were fertilized by ICSI. Moreover, the incidence of apoptosis in the granulosa cells enclosing the oocytes that grew into good-quality or fair-quality embryos was significantly lower after conventional IVF than after ICSI. With ICSI, the incidence of apoptosis was not significantly different among the granulosa cells surrounding the oocytes that were inseminated, were fertilized, or developed into good-quality or fair-quality embryos. With IVF, the incidence of apoptosis was highest in the granulosa cells surrounding the oocytes that were inseminated and lowest in the granulosa cells surrounding the oocytes that developed into good-quality and fair-quality embryos. CONCLUSION(s): A good-quality oocyte is necessary for the development of a good-quality embryo with IVF but not with ICSI. Thus, relatively poor oocyte quality is a good indication for the use of ICSI.
Fertility and Sterility 04/2000; 73(3):465-9. · 3.56 Impact Factor
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ABSTRACT: To determine whether folliculogenesis is impaired in patients with endometriosis.
Prospective study.
Yamagata University School of Medicine, Yamagata, Japan.
Thirty women participating in an IVF program.
The patients were divided into four groups according to the cause of their infertility: tubal factor (T), n = 7; male factor (M), n = 7; idiopathic (I), n = 7; and endometriosis (E), n = 9. Granulosa cells were obtained from the follicular fluid of each patient and analyzed by flow cytometry.
The percentage of granulosa cells in each cell-cycle stage.
The mean (+/- SD) rate of apoptosis in the granulosa cells obtained from the patients with endometriosis was the highest among the four groups (T = 11.7% +/- 3.3%; M = 5.6% +/- 3.8%; I = 9.6% +/- 5.1%; and E = 18.6% +/- 9.6%). The percentage of S-phase granulosa cells was significantly higher in the patients with endometriosis than in all the other patients combined (E = 12.5% +/- 6%; T + M + I = 9.3% +/- 2.9%). The percentage of G2/M-phase granulosa cells was significantly lower in the endometriosis group than in the other three groups combined (E = 2.3% +/- 2.5%; T + M + I = 4.6% +/- 2.1%).
Endometriosis impairs the cell cycle in granulosa cells. This phenomenon may have a detrimental effect on folliculogenesis.
Fertility and Sterility 03/2000; 73(2):344-50. · 3.56 Impact Factor
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ABSTRACT: To solve the problem of multiple pregnancies during the in vitro fertilization (IVF) and embryo transfer procedure, excess embryos must be cryopreserved for embryo transfer in future. We applied the vitrification method to cryopreservation of human embryos. A total of 31 frozen-thawed embryo transfer cycles were analyzed at the Yamagata University Hospital, Yamagata, Japan. The patients were introduced to IVF treatment and had an excess of valuable embryos to be frozen after the transfer of three fresh embryos that did not result in establishing a pregnancy. Excess human 8- to 16-cell stage embryos were exposed to vitrification solution and then frozen in liquid nitrogen. The cryoprotectant was removed by washing the embryos in media containing different concentrations of cryoprotectant. Three days after LH surge and/or 2 days after ultrasonographic ovulation the embryos were transferred. The rate of poor quality embryos significantly increased and the rate of good quality embryos decreased after thawing the embryos frozen by the vitrification method. In menstrual cycles with good quality embryo transfer, a higher rate of pregnancies was established than in the cycles in which fair or poor quality embryos were the highest grade of embryos transferred into the uterus. In total, 5 pregnancies were established from 31 embryo tansfers; 4 pregnancies were in cycles associated with the transfer of good quality embryos, and 1 pregnancy was in a cycle in which the highest grade of embryo was fair. When compared with slow embryo freezing methods, vitrification has marked advantages for clinical application in terms of cost and time. Vitrification will be an alternative method for embryo freezing.
Gynecologic and Obstetric Investigation 02/2000; 49(3):145-9. · 1.28 Impact Factor
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ABSTRACT: Gonadotropin-releasing hormone (GnRH) has been found to be expressed in ovaries of various species and to modulate cell differentiation in ovarian cells. GnRH agonists (GnRHa) are widely used in the stimulation protocols of assisted reproduction. In the present study, the direct effects of a GnRHa on the incidence of apoptosis and sterodogenesis in porcine in human granulosa cells were investigated. Cells were obtained from 6-month-old swine and in vitro fertilization patients, and cultured in minimum essential medium (MEM) supplemented with 5% fetal bovine serum for 24 h. The GnRHa (burserelin acetate) was added to the MEM at various concentrations (0, 5, 50, 500 pg/ml, and 5 ng/ml). The nuclei of granulosa cells were examined by fluorescence microscopy after Hoechst 33258 staining, and the incidence of apoptotic cells was tabulated. The GnRHa directly increased the incidence of apoptosis in both types of granulosa cells. The concentration of GnRHa in clinical use is much higher than the concentration which produced apoptosis in granulosa cells here. The clinical dosage of GnRHa should be reconsidered with regard to its apoptosis-inducing effect.
Gynecologic and Obstetric Investigation 02/2000; 49(1):52-6. · 1.28 Impact Factor
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ABSTRACT: Many researchers have discussed fecundity on a per patient or per ovarian follicle basis. In contrast, this study was undertaken on a per ovary basis, and tests the hypothesis that there is a relationship between the fecundity of the bilateral ovaries in an individual patient and the incidence of apoptotic granulosa cells. The two ovaries of 10 women undergoing ovulation induction for in-vitro fertilization (IVF) with gonadotrophin-releasing hormone analogue (GnRHa) and gonadotrophins were compared. There was no difference in apoptotic index in granulosa cells and various hormones in the follicular fluids. Our results indicate that, in the ovulation induction protocol for IVF, GnRHa and gonadotrophins, there is no predisposition of one ovary over the other in an individual patient in terms of apoptosis at the time of aspiration, even though the number of oocytes in each ovary is different, because the number of oocytes retrieved may reveal ovarian fecundity before stimulation with GnRHa + human menopausal gonadotrophin (HMG).
Human Reproduction 02/1999; 14(1):156-61. · 4.47 Impact Factor
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ABSTRACT: CD44 is a polymorphic and polyfunctional transmembrane glycoprotein widely expressed in many types of cells. Here, the expression of this protein on human membrana granulosa was studied by two techniques. Using confocal laser scanning microscopy (CLSM) with the mouse monoclonal antibody to human CD44 (clone G44-26), cells immunoreactive for CD44 were observed in both cumulus and mural granulosa cell masses. On the other hand, using monoclonal antibody to human CD44v9, goat polyclonal antibody to human CD44v3-10 and the clone G44-26, no immunoreactivity for CD44v9 and/or CD44v3-10 was observed in either cell group by flow cytometry. In the flow cytometric analysis of 32 patients, the incidence of CD44 expression in cumulus cells (62.6+/-1.3%) was significantly higher than that in mural granulosa cells (38.5+/-3.2%) (P<0.0001). In the comparison of CD44 expression by flow cytometry according to the maturation of each cumulus-oocyte complex, the incidence of CD44 expression of cumulus cells was significantly higher in the mature group than in the immature group (P<0.05). In a flow cytometric analysis, patients with endometriosis showed a significantly lower incidence of CD44 expression in cumulus cells compared to the infertility of unknown origin group (P<0.05), and compared to both the male infertility group and the unknown origin group in mural granulosa cells (P<0.01). These findings suggest that the standard form of CD44 is expressed in human membrana granulosa with polarity and may play an important role in oocyte maturation.
Molecular Human Reproduction 01/1999; 5(1):22-8. · 3.85 Impact Factor
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ABSTRACT: To investigate the incidence of apoptotic bodies in membrana granulosa in patients with endometriosis.
Retrospective analysis.
Yamagata University Hospital.
Fifty-eight normoovulatory women with endometriosis and 45 patients with male factor infertility underwent ovulation induction for IVF-ET with GnRH analogues and gonadotropins.
Patients underwent follicle aspiration after the administration of hCG.
Recovered granulosa cells (GCs) were examined by fluorescence microscopy, and the incidence of apoptotic bodies was tabulated. These data and the other parameters associated with IVF results were analyzed on the basis of both the revised American Fertility Society (AFS) classification of endometriosis and the existence of chocolate cysts.
The incidence of apoptotic bodies in membrana granulosa of patients with endometriosis was significantly higher than that of the control (male factor infertility) group and increased as the stage of the revised AFS classification advanced. The incidence of apoptotic bodies in membrana granulosa was significantly higher in patients with chocolate cysts than in those without chocolate cysts. The patients with endometriosis had smaller numbers of developed follicles (> or = 15 mm), harvested oocytes, and mature oocytes than the male factor infertility patients. The existence of chocolate cysts corresponded with a reduced number of both harvested oocytes and mature oocytes.
Through the apoptosis of GCs, the existence of endometriosis may have negatively affected the follicle development and oocyte quality.
Fertility and Sterility 05/1998; 69(5):931-5. · 3.56 Impact Factor
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ABSTRACT: To investigate the relationship between the incidence of apoptotic bodies in membrana granulosa and follicular steroid concentrations in human follicles.
Case-controlled prospective study for 132 individual follicles.
Procedures were performed in Yamagata University Hospital.
Thirty-six normo-ovulatory women with tubal infertility underwent ovulation induction for IVF-ET with a conventional hyperstimulation method.
Patients underwent follicle aspiration after the administration of hCG.
The nuclei of recovered granulosa cells were examined by fluorescence microscopy, and the incidence of apoptotic bodies was tabulated. Intrafollicular steroids were evaluated mainly by RIA. These data were analyzed with respect to oocyte-retrieval, oocyte maturity, fertilization, and embryo quality.
Membrana granulosa cells in the follicles from which oocytes were subsequently fertilized showed a significantly lower incidence of apoptotic bodies than those in follicles from which the oocytes did not fertilize. Membrana granulosa cells in the follicles from which oocytes were developed into good quality showed a significantly lower incidence of apoptotic bodies than those in the follicles from which oocytes developed into fair and poor quality. The incidence of apoptotic bodies was significantly higher in the mural granulosa cell region than in the cumulus cell region in most cases. Intrafollicular E2, P, and free T levels were not different between the oocyte groups.
These results indicate that lower incidence of apoptotic bodies in individual follicles is associated with better outcomes for oocytes. Also, mural granulosa cells and cumulus cell in each follicle may show differentiation during follicular maturation.
Fertility and Sterility 09/1997; 68(2):312-7. · 3.56 Impact Factor
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ABSTRACT: To determine the best equilibration time in the cryoprotectant before rapid cooling, 8-cell mouse embryos were exposed to a vitrification solution containing ethylene glycol, Ficoll and trehalose in modified phosphate-buffered saline at 5 degrees C for varying periods of time. They were frozen using an ultra rapid freezing method, thawed in a 20 degrees C water bath and cultured for 24 h with 5-bromo-2-deoxyuridine. Embryo development and the number of sister chromatid exchanges, a sensitive indicator of genetic damage, were observed. The results demonstrated that embryo development after freezing and thawing was similar among the groups exposed for periods of 5-40 min. However, the number of sister chromatid exchanges was significantly smaller in the group exposed for 5 min, indicating that this was the safest equilibration time in the vitrification solution.
Human Reproduction 07/1997; 12(6):1259-62. · 4.47 Impact Factor
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ABSTRACT: To investigate the incidence of apoptotic bodies in mural granulosa cell masses and cumulus cell masses.
Nonrandomized, prospective study.
Department of Obstetrics and Gynecology, Yamagata University School of Medicine, Yamagata, Japan.
One hundred twenty-nine normally ovulating women underwent ovulation induction for IVF-ET with GnRH analogue (GnRH-a) and gonadotropins.
Patients underwent follicle aspiration after the administration of hCG.
The nuclei of recovered granulosa cells were examined by fluorescence microscopy and the incidence of apoptotic bodies was tabulated.
The incidence of apoptotic bodies was significantly higher in mural granulosa cell masses than in cumulus cell masses in the entire group of 129 patients. Both incidence of apoptotic bodies of mural granulosa cell masses and cumulus cell masses were significantly higher in patients with less than six follicular oocytes compared with patients with six or more oocytes. Nonpregnant patients showed significantly higher incidence of apoptotic bodies in mural granulosa cell masses compared with pregnant patients.
These results indicate that mural granulosa cell masses and cumulus cell masses may have different functions in follicular maturation. The incidence of apoptotic bodies in mural granulosa cell masses can be used as an indicator of success of IVF.
Fertility and Sterility 03/1997; 67(2):302-8. · 3.56 Impact Factor
