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Tsutomu Sawada

Publications and source records attributed to Tsutomu Sawada.

At least 19 recordsLinked to original sources
PubMed2006

Three-dimensional centimeter-sized colloidal silica crystals formed by addition of base.

Three-dimensional (3D) centimeter-sized colloidal crystals can be spontaneously formed simply by dropping a NaOH solution (10 mM, approximately 10 microL) into an aqueous dispersion of dilute charged colloidal silica (particle diameter 110 nm, particle volume fraction phi = 0.023, 3-4 mL). The charge number of the silica particle increases with pH. Upon adding the NaOH solution, first, sub-millimeter-sized polycrystals are formed in the upper part of the sample due to charge-induced crystallization. The local phi value in the crystal region becomes nonuniform. The crystals with a high phi value accumulate at the bottom of the cell and then grow upward as columnar crystals. The crystal widths increase discontinuously with the growth, and in some cases, 3D centimeter-sized crystals are formed. The centimeter-sized crystals are also obtainable by the controlled diffusion of the base from its dilute reservoir. The present findings may prove valuable in the fabrication of large 3D single-crystalline photonic materials.

Colloids↗
PubMed2006

Monte Carlo simulation of crystal-fluid coexistence states in the hard-sphere system under gravity with stepwise control.

Monte Carlo (MC) simulations were performed for hard spheres (with diameter sigma and mass m) placed between well-separated upper and lower hard walls. A periodic boundary condition was imposed in the horizontal direction. The system was exposed to the gravitational field with the acceleration due to gravity g. After preparing a melt as the initial state, g was increased stepwise up to mgsigma/k(B)T(identical with g(*))=1.5 or 2.0 with an increment Deltag(*) = 0.1; k(B)T is the temperature multiplied by Boltzmann's constant. We maintained g(*) at each value for 2.0 x 10(5) MC cycles. The transition of the system into a metastable state such as a polycrystalline state due to trapping phenomena was successfully avoided. A monotonic increase and subsequent saturation were observed for the development of the crystalline region formed at the bottom of the system. The development of this region accompanied a shrinkage of the defective (or less ordered) crystalline region that was formed between the bottom region and the fluid phase. As the development of the bottom region almost saturated, the defective region grew upward again.

Journal Article↗
PubMed2006

Inhibitory effects of CIDR-based ovulation-synchronization protocols on uterine PGF2alpha secretion at the following luteal phase in early postpartum non-cycling beef cows.

We investigated whether CIDR-based ovulation-synchronization protocols inhibit secretion of prostaglandin (PG) F2alpha from the uterus in the following luteal phase in non-cycling beef cows. Ten early (a month) postpartum non-cycling Japanese Black beef cows were treated with (1) Ovsynch (GnRH analogue on Day 0, PGF2alpha analogue on Day 7, and GnRH analogue on Day 9; n=3), (2) Ovsynch+CIDR (Ovsynch protocol plus a CIDR for 7 days from Day 0; n=4), or (3) estradiol benzoate (EB) Ovsynch+CIDR (EB on Day 0 in lieu of the first GnRH treatment followed by the Ovsynch+CIDR protocol; n=3). An oxytocin challenge was administered on Day 24 to examine uterine PGF2alpha secretion. Plasma concentrations of 13,14-dihydro-15-keto- PGF2alpha were lower at 30-120 min after oxytocin administration in the Ovsynch+CIDR group and 75 min after administration in the EB Ovsynch+CIDR group than in the Ovsynch group (P<0.05). Plasma progesterone concentrations were higher from Days 1 to 7 in the Ovsynch+CIDR group and from Days 1 to 5 in the EB Ovsynch+CIDR group than in the Ovsynch group (P<0.05). The progesterone concentrations were higher on Days 27 and 29 in both CIDR-treated groups than in the Ovsynch group (P<0.05). In conclusion, in non-cycling beef cows, CIDR-based ovulation-synchronization protocols inhibit uterine PGF2alpha secretion in the following luteal phase and prevent premature luteolysis as is seen with the Ovsynch protocol.

Administration, Intravaginal↗
PubMed2006

Optical Detection of Nonequilibrium Swelling Behavior of a Polymer Gel upon Solvent Substitution.

We report a novel transient swelling and shrinking behavior of a thin poly(acrylamide)-based gel film upon solvent substitution between water and ethylene glycol. These size changes could be optically detected through a change in the Bragg diffraction wavelength for the colloidal crystal of charged polystyrene latex particles that was fixed in the gel. The transient size change that was observed in this study could not be explained on the basis of the equilibrium characteristics, but it was attributable to the transient variation of osmotic pressure in the gel.

Journal Article↗
PubMed2006

Photonic rubber sheets with tunable color by elastic deformation.

This article describes an elastic silicone sheet with reversible tuning structural color. The sheet has a thin layer of cubic close-packed, ccp, colloidal particles embedded in poly(dimethylsiloxane), PDMS, elastomer. The array of ccp (111) planes diffracts light of selective wavelengths according to Bragg's law. This is responsible for the structural color of the PDMS sheet. Because the sheet was stretched in the horizontal direction, it was reduced in size in the vertical direction. As a result, the lattice distance of ccp (111) planes decreased, and the reflected wavelength of light shifted to shorter wavelengths. For example, the peak of reflection was tuned from 589 to 563 nm as a function of sheet elongation. The peak position decreased linearly with deformation when the deformation was within 20% of its elongation. Accordingly, the color of the PDMS sheet changed from red to green. When the mechanical strain on the PDMS sheet was released, the peak returned to its original position, and the color of the PDMS sheet also changed back to red. Tuning the color of the PDMS sheet is a reversible and repeatable process. The novel PDMS sheet has the potential to be applied to mechanical strain sensing.

Journal Article↗
PubMed2006

Isolation and characterization of embryonic stem-like cells from canine blastocysts.

Embryonic stem (ES) cells are pluripotent cells with the capacity to generate any type of cell. Here we describe the isolation of ES-like cells from canine blastocysts. Canine embryos were collected from beagle bitches at day 11-16 of first estrus. A total of 80 normal embryos were obtained from 15 dogs. Of the embryos, 13 were at the morulae stage, 39 at the blastocyst stage, and 28 at the hatched blastocyst stage. The inside of morulae or inner cell masses (ICMs) of blastocysts were isolated mechanically, and cultured onto mouse embryonic fibroblasts (MEF) as feeder layers. Primary cell colonies were formed in 0% (0/13) of morulae, 25.6% (10/39) of blastocysts, and 67.9% (19/28) of hatched blastocysts. These colonies were separated either by enzymatic dissociation or by mechanical disaggregation. Dissociation with collagenase resulted in immediate differentiation, but with mechanical disaggregation these cells remained undifferentiated, and two ES-like cell lines (cES1, cES2) continued to grow in culture after eight passages. These cells had typical stem cell-like morphology and expressed specific markers such as alkaline phosphatase activity, stage specific embryonic antigen-1 and Oct-4. These cells formed embryoid bodies (EBs) in a suspension culture; extended culture of EBs resulted in the formation of cystic EBs. When the simple EBs were cultured on tissue culture plates, they differentiated into several types of cells including neuron-like, epithelium-like, fibroblast-like, melanocyte-like, and myocardium-like cells. These observations indicate that we successfully isolated and characterized canine ES-like cells.

Animals↗
PubMed2006

Macromorphometric study on ciliary body location in canine eyes.

This macroscopic study firstly examined the precise locational information of the canine ciliary body, i.e., the ciliary crown and the ciliary ring in the beagle. The safe and effective transscleral laser photocoagulation technique requires the accurate location of the ciliary body. In both sides of the eyeball in 10 beagle dogs, the width of the ciliary ring and the distance from the limbus to the ciliary ring were measured with calipers using a stereomicroscope at the 8 points. The widest portion of ciliary body was found at the dorsal to ventro-temporal area of the lateral canthus (lateral portion of the eyelid; ear side). In contrast, the narrowest portion was seen at the ventro-nasal to nasal area of the medial canthus (medial portion of the eyelid; nasal quadrants). Use of transscleral photocoagulation at the present narrowest area of ciliary body may carry a high risk of destruction of the optic portion of retina.

Animals↗
PubMed2005

Relations between plasma IGF-I concentrations during treatment with CIDR-based or Ovsynch protocol for timed AI and conception in early postpartum Japanese black beef cows.

We examined the relations between plasma insulin-like growth factor (IGF) -I concentrations during treatment with CIDR-based or Ovsynch protocol for timed AI and conception and plasma steroid concentrations in early postpartum Japanese Black beef cows. Cows in the control group (Ovsynch; n = 21) underwent Ovsynch protocol (GnRH analogue on Day 0, PGF(2alpha) analogue on Day 7, and GnRH analogue on Day 9), with AI on Day 10, approximately 20 h after the second GnRH treatment. Cows in the Ovsynch+CIDR group (n = 22) received Ovsynch protocol plus a CIDR for 7 days (starting on Day 0). Cows in the further treatment group (EB+CIDR+GnRH; n = 22) received 2 mg of estradiol benzoate (EB) on Day 0 in lieu of the first GnRH treatment, followed by the same treatment as in the Ovsynch+CIDR protocol. Plasma IGF-I concentrations were determined on Days -7, 0, 7, 9 and 17. Conception rates were improved in the CIDR-combined groups (both CIDR-treated groups were combined) relative to Ovsynch group (P < 0.05) for cows with low IGF-I concentrations (<1,000 ng/ml) on Days -7, 0, and 7, but improved conception rate produced by the CIDR-based protocols did not occur in cows with a high IGF-I concentration (> or =1,000 ng/ml). Plasma estradiol-17beta concentrations increased from Day 0 to 7 (P < 0.05) and were unchanged from Day 7 to 9 in the Ovsynch group with low IGF-I concentrations on Day 0, while they were unchanged from Day 0 to 7 and increased from Day 7 to 9 (P < 0.05) in the Ovsynch group with high IGF-I concentrations on Day 0 and in the CIDR-combined group. Plasma progesterone concentrations in the Ovsynch group with low IGF-I concentrations on Day 0 were higher on Day 14 than in the Ovsynch group with high IGF-I concentrations on Day 0 and in the CIDR-combined group (P < 0.05). In conclusion, CIDR-based protocols may improve conception relative to Ovsynch in early postpartum beef cows with lower plasma IGF-I concentrations at the start of the protocols. This improvement is probably due to prevention of premature increases of estradiol-17beta and progesterone concentrations, which occurred in cows with low IGF-I concentrations treated with Ovsynch, by the CIDR treatment.

Animals↗
PubMed2005

Gelation of colloidal crystals without degradation in their transmission quality and chemical tuning.

A single-domain colloidal crystal with high transmission quality, prepared by a shear-induced process, was fixed as a hydrogel film by photopolymerization. Upon gelation, the original optical quality was almost perfectly preserved. By replacing the solvent, the gelled crystal could be converted to smaller lattice constant crystals without significant degradation in its transmission characteristics. The conversion results in a stop-band wavelength coverage across the entire visible light range.

Letter↗
PubMed2005

Critical concentration for colloidal crystallization determined with microliter centrifuged suspensions.

We report an elegant method using centrifugal sedimentation for determining the critical particle concentration for colloidal crystallization. A small amount of a dilute suspension of monodispersed particles stored in a flat capillary cell was centrifuged to temporarily generate a nonequilibrium gradient of the particle concentration including a crystalline-noncrystalline phase boundary in the cell. In the recovering process after the centrifugation, the particle concentration of the crystalline phase at the boundary was found to always have the equilibrium value, although the global concentration distribution evolved with time. The critical concentration was determined based on spatially resolved spectrometry. The present method requires only one batch of a suspension of the order of microliters and is applicable up to high concentration regions near the closest packing without the effect of the particle aggregation.

Journal Article↗
PubMed2005

Adenomyosis with severe inflammation in the uterine cervix in a dog.

A dog with purulent vulval discharge was found to have many cysts containing purulent mucus in the uterine cervix. The uterine horns did not contain any pus. Histological examination revealed a cervical adenomyosis infiltrated by many neutrophils. After an ovariohysterectomy including the whole cervix, the dog recovered well.

Animals↗
PubMed2004

Equilibrium characteristic at ordered-disordered phase boundary in centrifuged nonequilibrium colloidal-crystal system.

We show that a crystalline-noncrystalline boundary that temporarily appeared in a sediment centrifuged from a relatively dilute colloidal suspension can be regarded to be at a phase equilibrium. On the basis of this, we can determine the critical particle concentration for colloidal crystallization using an extremely small amount of specimen by spatially resolved spectroscopy.

Journal Article↗
PubMed2004

One-directional crystal growth in charged colloidal silica dispersions driven by diffusion of base.

Aqueous dispersions of charged colloidal silica particles showed a novel one-directional crystal growth by diffusion of a weak base, pyridine. The colloidal crystal consisted of pillar-shaped crystal grains whose height and width were in the order of centimeter and subcentimeter, respectively. The growth process was explainable in terms of (i) the diffusion of pyridine with neutralization reactions between weakly acidic silica surfaces, (ii) charging up of the silica particles, and (iii) the charge-induced crystallization of the dispersions.

Journal Article↗
PubMed2004

Enhancement of prostacyclin synthesis at the beginning of formation of caprine corpora lutea.

We examined changes in the levels of prostacyclin (PGI2) synthase mRNA and 6-keto-PGF1alpha, a stable metabolite of PGI2, in the caprine corpus luteum (CL) during its development and subsequent maintenance. We also looked at the effects of a potent GnRH antagonist (GA), which is known to suppress the release of luteinizing hormone (LH), on the PGI2 synthase mRNA level and the 6-keto-PGF1alpha content during CL development. Goats were divided into a control group (n=12) and a GA-treated group (n=6). They were treated with saline or GA (50 microg/kg, s.c.) on days 0 (day of ovulation), 4, and 8 (control only), and the CL were collected from a subset of goats (n=3 for each day) on days 0 (no saline), 4, 8, or 14 (control only). Ribonuclease protection assay was performed to quantify the mRNA in the CL using specific cRNA probes generated by RT-PCR and in vitro transcription. The 6-keto-PGF1alpha content in the CL was measured by radioimmunoassay. The level of PGI2 synthase mRNA and the 6-keto-PGF1alpha content in the CL in the control group decreased from day 0 to day 4 (P<0.01), and did not change thereafter from day 4 to day 14. Levels of PGI2 synthase mRNA and 6-keto-PGF1alpha content in the CL on days 4 and 8 were not affected by treatment with GA. These results suggest that PGI2 synthesis is regulated upward at the beginning of caprine CL formation; this may play a role in initiating CL development. This study also suggests that changes of PGI2 synthesis during CL development are probably not regulated by LH.

6-Ketoprostaglandin F1 alpha↗
PubMed2004

Effect of ovarian hormones on periodical changes in immune resistance associated with estrous cycle in the beagle bitch.

In bitches, the onset of pyometra, an infection of the uterus, characteristically occurs in the first half of the diestrous stage in the estrous cycle, in which the blood concentration of progesterone peaks and that of estradiol-17beta is lowest. To investigate the immunological mechanisms governing stage-specific onset of pyometra, peripheral blood mononuclear cells (PBMNCs) were collected from beagle bitches during different stages of the estrous cycle and examined using various immunological assays. When we examined the proliferative response of PBMNCs to PYO-252, that is a clone of Escherichia coli isolated from the uterus of a dog afflicted with pyometra, the response of PBMNCs significantly decreased in the first half (day 10) of diestrus, but increased in proestrus/estrus. No significant differences were observed in the responses to concanavaline A between stages of the cycle. Throughout the estrous cycle, canine PBMNCs did not respond to lipopolysaccharide derived from E. coli. The response of PBMNCs collected in anestrus to PYO-252 was significantly enhanced upon the addition of estradiol-17beta to the culture. In contrast, these responses were significantly suppressed in the presence of progesterone. Progesterone progenitor or metabolite molecules, which have a low affinity for the progesterone receptor, did not affect proliferative responses. Expression of gamma interferon (IFNgamma) in response to PYO-252 was also significantly enhanced by estradiol-17beta, but suppressed by progesterone. This evidence suggests that in the first half of the diestrous stage, suppressed activity of cellular immunity results from increasing progesterone concentration and minimal estrogen release. This marked decrease of immune resistance allows the expansion of E. coli, which enter the uterine cavity through the loosened cervical canal during estrus, leading to pyometra onset.

Animals↗
PubMed2003

Expression of estrogen receptor alpha and beta genes in the mediobasal hypothalamus, pituitary and ovary during the canine estrous cycle.

Estrogen receptor alpha (ERalpha) and ERbeta mRNA levels were measured in the mediobasal hypothalamus, the anterior pituitary and the ovary of beagle bitches at various stages of the estrous cycle. With polymerase chain reaction analysis we detected ERbeta gene transcripts in all tissue samples. The levels of hypothalamic and pituitary ERalpha and beta mRNAs increased from mid anestrus to proestrus and declined thereafter. In the ovary, ERalpha mRNA levels increased from proestrus to diestrus and were positively correlated with plasma progesterone levels (r=0.62, P<0.01), whereas ERbeta mRNA levels increased from mid anestrus to proestrus and were positively correlated with plasma estradiol-17beta levels (r=0.73, P<0.001). These results suggest that the rise in hypothalamic and pituitary ERalpha and beta mRNAs is associated with termination of anestrus, and that increases in ovarian ERalpha and beta mRNAs may be involved in initiating development of the follicle or corpora lutea.

Animals↗
PubMed2003

Changes of messenger RNAs encoding vascular endothelial growth factor and its receptors during the development and maintenance of caprine corpora lutea.

The present study was conducted to examine changes of mRNAs encoding vascular endothelial growth factor (VEGF) and its receptors (KDR/Flk-1 and Flt-1), and CD34, which is known to be a specific marker for endothelial cells, during the development and maintenance of the caprine corpora lutea (CL). Effects of a potent GnRH antagonist (GA), which was previously shown to suppress release of luteinizing hormone (LH), on expressions of those mRNAs during the CL development were also investigated. Goats were divided into control (n = 12) and GA-treated groups (n = 6). The goats were treated with saline or GA (50 microg/kg, sc) on days 0 (day of ovulation), 4, and 8 (control only), and CL collected on a subset of goats (n = 3 for each day) on days 0 (no saline), 4, 8, or 14 (control only). Ribonuclease protection assay was performed to quantitate the mRNAs in the CL using specific cRNA probes generated by RT-PCR and in vitro transcription. Level of CD34 mRNA significantly increased from day 0 to 8 (CL development) in the control group (P < 0.05). Long and short forms were detected in the caprine CL by RT-PCR for VEGF mRNA and analyses of their sequences showed that they correspond to mRNAs encoding VEGF(165) and VEGF(121), respectively. Level of VEGF(165) mRNA significantly increased from day 4 to 8 and day 8 to 14 (CL maintenance) in the control group (P < 0.05) while VEGF(121) mRNA did not change during the whole period. Level of KDR/Flk-1 mRNA significantly increased from day 0 to 8 (P < 0.05) while Flt-1 mRNA significantly increased from day 8 to 14 (P < 0.005) in the control group. In the GA-treated group, levels of all of the mRNAs did not alter remarkably as compared with those in the control group. These results suggest that rise of KDR/Flk-1 and VEGF(165) mRNAs during the caprine CL development may be associated with enhanced angiogenesis and that increment of VEGF(165) and Flt-1 mRNAs during the CL maintenance may play nonangiogenic roles. The present study also indicates that the changes of VEGF(165) and KDR/Flk-1 mRNAs during the CL development are probably not regulated by LH.

Animals↗