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Yuki Sato

Publications and source records attributed to Yuki Sato.

At least 37 records · Page 2Linked to original sources
PubMed2005

Chronopharmacological study of antidepressants in forced swimming test of mice.

The influence of dosing time on the anti-immobility effect of antidepressants and mechanisms underlying this phenomenon were investigated in mice. In the forced swimming test (FST), the immobility time of mice treated with amitriptyline (15 mg/kg) and fluvoxamine (30 mg/kg) showed a significant 24-h rhythm. The anti-immobility effect of fluvoxamine in FST was potent at the early part of the dark phase without increasing locomotor activity. Concerning pharmacokinetics, although K(e) of fluvoxamine was approximately 1.3-fold higher in mice injected with fluvoxamine at 9:00 PM than at 9:00 AM, no dosing time dependence was demonstrated for either plasma or brain fluvoxamine concentration at 0.5 h after the drug injection. On the other hand, serotonin transporter (SERT) mRNA expression and 5-hydroxytryptamine (5-HT) uptake activity in the mouse midbrain showed significant time-dependent changes with higher levels during the dark phase and lower levels during the light phase. These results suggest that the reuptake of 5-HT might be more increased during the dark phase. Since the reuptake of 5-HT is inhibited almost completely by injection with 30 mg/kg fluvoxamine at any time, the extracellular 5-HT level may be more increased by the injection of fluvoxamine at the early part of the dark phase. The present results suggest that the anti-immobility effect of fluvoxamine in FST increases depending on dosing time. Furthermore, the time-dependent change of SERT mRNA expression and uptake activity in the midbrain is suggested to be the mechanism underlying the 24-h rhythm of anti-immobility effect of fluvoxamine.

Animals↗
PubMed2005

A novel signal induces a segmentation fissure by acting in a ventral-to-dorsal direction in the presomitic mesoderm.

We describe here a novel inductive action that operates during somitic segmentation in chicken embryos. We previously reported that the posterior border cells located at a next-forming boundary in the anterior end of the presomitic mesoderm (PSM) exhibit an inductive activity that acts on the anterior cells to cause the formation of a somitic fissure (Sato, Y., Yasuda, K., Takahashi, Y., 2002. Morphological boundary forms by a novel inductive event mediated by Lunatic fringe and Notch during somitic segmentation. Development 129, 3633-3644). In this study, we have found a second inductive action along the dorso-ventral (D-V) axis during fissure formation. When relocated into a non-segmenting region of PSM, the ventral-most cells taken from the presumptive boundary are sufficient to induce an ectopic fissure in host cells. The ventrally derived signal acts in a ventral-to-dorsal direction but not ventrally, regardless of where the ventral cells are placed. This directional signaling is governed, at least in part, by the signal-receiving cells of the PSM, which we found to be polarized along the D-V axis, and also by intimate cell-cell interactions. Finally, we have observed that morphological segmentation is able to rearrange the anterior and posterior regionalization of individual somites. These findings suggest that discrete unidirectional signals along both the antero-posterior and the D-V axes act coordinately to achieve the formation of the intersomitic fissure, and also that fissure formation is important for the fine-tuning of A-P regionalization in individual somites.

Animals↗
PubMed2005

Mutually exclusive glomerular innervation by two distinct types of olfactory sensory neurons revealed in transgenic zebrafish.

The olfactory epithelium of fish contains two major types of olfactory sensory neurons (OSNs) that are distinct morphologically (ciliated vs microvillous) and possibly functionally. Here, we found that these OSNs express different sets of signal transduction machineries: the ciliated OSNs express OR-type odorant receptors, cyclic nucleotide-gated channel A2 subunit, and olfactory marker protein (OMP), whereas the microvillous OSNs express V2R-type receptors and transient receptor potential channel C2 (TRPC2). To visualize patterns of axonal projection from the two types of OSNs to the olfactory bulb (OB), we generated transgenic zebrafish in which spectrally distinct fluorescent proteins are expressed in the ciliated and microvillous OSNs under the control of OMP and TRPC2 gene promoters, respectively. An observation of whole-mount OB in adult double-transgenic zebrafish revealed that the ciliated OSNs project axons mostly to the dorsal and medial regions of the OB, whereas the microvillous OSNs project axons to the lateral region of the OB. A careful histological examination of OB sections clarified that the axons from the two distinct types of OSNs target different glomeruli in a mutually exclusive manner. This segregation is already established at very early developmental stages in zebrafish embryos. These findings clearly demonstrate the relationships among cell morphology, molecular signatures, and axonal terminations of the two distinct types of OSNs and suggest that the two segregated neural pathways are responsible for coding and processing of different types of odor information in the zebrafish olfactory system.

Animals↗
PubMed2005

Development of new inbred transgenic strains of rats with LacZ or GFP.

The ideal goal of regeneration medicine is to restore form and function to damaged tissues. While stem cell transplantation is considered a promising therapeutic approach, knowing the fate of transplanted cells using appropriate markers is essential. We developed new inbred transgenic rat strains with lacZ and GFP based on the transgenic (Tg) animal technique in rats. These Tg animals expressed most of their marker genes ubiquitously, compared to previous Tg rats. Immunological antigenicity against marker proteins was evaluated using conventional skin grafting, and results suggested lacZ-Tg-derived skin was much less immunogenic than that of GFP-Tg. However, GFP-positive cells from parental transgenic rats were still potential candidates for the study of cellular fate in immune privilege sites, such as the brain. Taking advantage of less immunogenic lacZ, we also examined the role of bone marrow-derived cells (BMDCs) in skin wound healing using an in vivo biological imaging system. Although transplantation of BMDCs enhanced wound healing at the injection site, BMDCs were detected only for a short time, suggesting a transient contribution of autologous BMDC-transplantation in wound healing. Our Tg-rat system may provide great benefits for the elucidation of the cellular process of regenerative medicine, including cell and tissue transplantation.

Animals↗
PubMed2005

Robo2 is required for establishment of a precise glomerular map in the zebrafish olfactory system.

Olfactory sensory neurons (OSNs) expressing a given odorant receptor project their axons to specific glomeruli, creating a topographic odor map in the olfactory bulb (OB). The mechanisms underlying axonal pathfinding of OSNs to their precise targets are not fully understood. Here, we demonstrate that Robo2/Slit signaling functions to guide nascent olfactory axons to the OB primordium in zebrafish. robo2 is transiently expressed in the olfactory placode during the initial phase of olfactory axon pathfinding. In the robo2 mutant, astray (ast), early growing olfactory axons misroute ventromedially or posteriorly, and often penetrate into the diencephalon without reaching the OB primordium. Four zebrafish Slit homologs are expressed in regions adjacent to the olfactory axon trajectory, consistent with their role as repulsive ligands for Robo2. Masking of endogenous Slit gradients by ubiquitous misexpression of Slit2 in transgenic fish causes posterior pathfinding errors that resemble the ast phenotype. We also found that the spatial arrangement of glomeruli in OB is perturbed in ast adults, suggesting an essential role for the initial olfactory axon scaffold in determining a topographic glomerular map. These data provide functional evidence for Robo2/Slit signaling in the establishment of olfactory neural circuitry in zebrafish.

Animals↗
PubMed2005

Gene silencing in rat-liver and limb grafts by rapid injection of small interference RNA.

Genetic modification is a promising therapeutic strategy for organ transplantation. In previous studies, we introduced a nonviral method of gene transfer to donor grafts using an organ-selective injection technique to up-regulate gene expression. Based on the attractive methodology of RNA interference for silencing a particular gene expression, we applied our catheter-based injection method to transfer small interference RNA (siRNA)-green fluorescence protein (GFP) into liver and limb grafts. We first quantified the interfering activity after the systemic delivery of siRNA in the liver of Alb-DsRed2 transgenic (Tg) rats using in vivo bioimaging system. Then, using GFP Tg Lewis rats as donors, transient down-regulation of the GFP expression was achieved both in liver- and limb-transplantation models by the preoperative rapid injection of siRNA. Genetic modification by siRNA may provide new therapeutic options for down-regulation of endogenous antigenicity.

Animals↗
PubMed2005

Effects of menstrual cycle and physical training on heat loss responses during dynamic exercise at moderate intensity in a temperate environment.

We evaluated the effects of the menstrual cycle and physical training on heat loss (sweating and cutaneous vasodilation) responses during moderate exercise in a temperate environment. Ten untrained (group U) and seven endurance-trained (group T) women (maximal O2 uptake of 36.7+/-1.1 vs. 49.4+/-1.7 ml.kg-1.min-1, respectively; P<0.05) performed a cycling exercise at 50% maximal O2 uptake for 30 min during both the midfollicular and midluteal menstrual phase in a temperate environment (ambient temperature of 25 degrees C, relative humidity of 45%). In group U, plasma levels of estrone, estradiol, and progesterone at rest and esophageal temperature (Tes) during exercise were significantly higher during the midluteal than during the midfollicular phase (P<0.05). Sweating rate and cutaneous blood flow (measured via laser-Doppler flowmetry) on the chest, back, forearm, and thigh were lower during the midluteal than during the midfollicular phase during exercise. Tes threshold for heat loss responses was significantly higher and sensitivity of the heat loss responses was significantly lower in the midluteal than in the midfollicular phase, regardless of body site. These effects of the menstrual cycle in group U were not observed in group T. The sweating rate and cutaneous blood flow were significantly higher in group T than in group U, regardless of menstrual phase or body site. Tes threshold for heat loss responses was significantly lower and sensitivity of heat loss responses was significantly greater in group T than in group U in the midluteal phase; however, sensitivity of the sweating response was significantly greater in the midfollicular phase. These results suggest that heat loss responses in group U were inhibited in the midluteal phase compared with in the midfollicular phase. Menstrual cycle had no remarkable effects in group T. Physical training improved heat loss responses, which was more marked in the midluteal than in the midfollicular phase.

Adult↗
PubMed2005

Health-related quality of life (HRQOL) in Japanese osteoporotic patients and its improvement by elcatonin treatment.

Health-related quality of life (HRQOL; "QOL" hereafter) was evaluated in Japanese osteoporotic patients using three questionnaires; the SF-36 (MOS 36-Item Short-Form Health Survey; generic, profile-type), the EQ-5D (Euro Qol-5 Dimensions; generic, preference-based), and the JOQOL (Japanese Osteoporosis Quality of Life 1999; disease-targeted). The eight subscales and two summary scores of the SF-36 were impaired in these patients even after correction for age and sex. The scores on the EQ-5D and JOQOL correlated well with the subscales of the SF-36 that represent the physical aspects of physical function and bodily pain, which suggests that physical aspects are important determinants of overall QOL status in osteoporotic patients. Although the QOL scores did not correlate with bone mineral density, they were markedly influenced by the presence of vertebral fractures. In particular, the presence of two or more vertebral fractures greatly decreased the QOL scores. We then evaluated the QOL scores before and after treatment. The patients were either given calcium supplementation alone or calcium plus once-weekly elcatonin (Elcitonin, Asahi Kasei Pharma, Tokyo, Japan) injection. Elcatonin treatment markedly improved diverse aspects of the QOL, whereas calcium alone did not. The current data suggest that osteoporosis, especially in the presence of vertebral fracture, is associated with compromised QOL, and therapeutic intervention for osteoporosis should be evaluated in terms of QOL, as well as in terms of increases in bone mineral density and fracture prevention.

Aged↗
PubMed2005

Transplantation of GABAergic neurons into adult mouse neocortex.

GABAergic neurons in the neocortex contribute to various brain functions by regulating cortical pyramidal neurons. A deficiency of GABAergic neurons in the neocortex leads to the dysregulation of cortical neuronal circuits, but this can be overcome by cell transplantation, which provides a practical approach to repair damaged neuronal circuits. Here, we focused on the transplantation of committed neuronal progenitor cells. Because neuronal differentiation is considerably suppressed in the adult neocortex, we transfected proneural bHLH transcription factors into neural precursor cells to commit them to a neuronal lineage prior to the cell transplantation. We show that ventral neural stem cells transfected with Ngn1 are integrated as GABAergic neurons within a few days of transplantation into the adult mouse neocortex. These results demonstrate that the transplantation of committed neuronal progenitor cells is an effective method for brain repair.

Age Factors↗
PubMed2005

Fruit and vegetable consumption and risk of colorectal cancer in Japan: The Miyagi Cohort Study.

OBJECTIVE: Adequate fruit and vegetable intake has been suggested to protect against colorectal cancer. However, several recent prospective studies have reported no association. We therefore examined the association between fruit and vegetable intakes and the risk of colorectal cancer in a prospective cohort study in Japan. DESIGN: Between June and August 1990, 47 605 Japanese men and women completed a self-administered questionnaire, including a food-frequency questionnaire. We divided the subjects into quartiles based on their self-reported fruit and vegetable consumption. There were 165 colon cancer and 110 rectal cancer incidences identified during 7 years of follow-up, to the end of December 1997. We used Cox proportional hazards models to estimate the relative risk (RR) of developing colorectal cancer according to the level of fruit and vegetable consumption, applying adjustments for potential confounders. RESULTS: No statistically significant association was observed between fruit and vegetable consumption and the risk of colorectal cancer. The multivariate RR of colon cancer in the highest quartile of fruit and vegetable intake compared with the lowest was 1.13 (95% confidence interval (CI) 0.73-1.75), the RR for vegetables alone was 1.24 (95% CI 0.79-1.95) and that for fruit alone was 1.45 (95% CI 0.85-2.47). The corresponding multivariate RRs for rectal cancer were 1.12 (95% CI 0.67-1.89), 1.14 (95% CI 0.67-1.93) and 1.41 (95% CI 0.73-2.73). CONCLUSIONS: We found no association between the consumption of fruit and vegetables and the risk of colorectal cancer among the Japanese population.

Adult↗
PubMed2005

Effect of N-methyl-D-aspartate receptor epsilon1 subunit gene disruption of the action of general anesthetic drugs in mice.

BACKGROUND: Recent molecular strategies demonstrated that the N-methyl-d-aspartate (NMDA) receptor is a major target site of anesthetic agents. In a previous article, the authors showed that knocking out the NMDA receptor epsilon1 subunit gene markedly reduced the hypnotic effect of ketamine in mice. In the current study, the authors examined the in vivo contribution of the NMDA receptor epsilon1 subunit to the action of other anesthetic drugs. METHODS: The authors determined the anesthetic effects of nitrous oxide on sevoflurane potency in NMDA receptor epsilon1 subunit knockout mice compared with those in wild-type mice. They then tested the hypnotic effect of gamma-aminobutyric acid-mediated agents, such as propofol, pentobarbital, diazepam, and midazolam, in knockout mice and wild-type mice. RESULTS: The anesthetic action of sevoflurane itself was unaffected by the abrogation of the NMDA receptor epsilon1 subunit. Adding nitrous oxide reduced the required concentration of sevoflurane to induce anesthesia in wild-type mice, whereas this sparing effect was diminished in knockout mice. Furthermore, propofol, pentobarbital, diazepam, and midazolam also had markedly attenuated effects in knockout mice. CONCLUSIONS: Although it has been demonstrated that knocking out the expression of receptors may induce changes in the composition of the subunits, the network circuitry, or both, the current findings show consistently that the NMDA receptor epsilon1 subunit mediates nitrous oxide but not sevoflurane anesthesia. Furthermore, the attenuated anesthetic impact of propofol, pentobarbital, diazepam, and midazolam as well as ketamine in knockout mice suggests that the NMDA receptor epsilon1 subunit could be indirectly involved in the hypnotic action of these drugs in vivo.

Anesthetics↗
PubMed2005

Mesenchymal-to-epithelial transition during somitic segmentation: a novel approach to studying the roles of Rho family GTPases in morphogenesis.

During early development in vertebrates, cells change their shapes dramatically both from epithelial to mesenchymal and also from mesenchymal to epithelial, enabling the body to form complex tissues and organs. Using somitogenesis as a novel model, Rho family GTPases have recently been shown to play essential and differential roles in individual cell behaviors in actual developing embryos. Levels of Cdc42 activity provide a binary switch wherein high Cdc42 levels allow the cells to remain mesenchymal, while low Cdc42 levels produce epithelialization. Rac1 activity needs to be precisely controlled for proper epithelialization through the bHLH transcription factor Paraxis. Somitogenesis is expected to serve as an excellent model with which one can understand how the functions of developmental genes are resolved into the morphogenetic behavior of individual cells.

Animals↗
PubMed2005

The dosing-time dependent effects of intravenous hypnotics in mice.

Chronobiology, which focuses on the biological rhythms that occur in the organization of living organisms, has been studied for several decades. Chronopharmacology, however, has received little attention until recently. We examined the hypnotic duration of intraperitoneally administered ketamine, pentobarbital, propofol, midazolam, and ethanol, to test whether they have obvious dosing-time dependent effects. Male C57BL/6 mice, which showed clear circadian rhythms of water-intake under a strict 12-h lighting cycle, were used. All tested drugs had significantly longer episodes of loss of righting reflex when administered at 22:00 (early active phase) than at 10:00 (early inactive phase). This dosing-time dependent hypnotic duration did not depend on the contents and activities of cytochrome P450 enzymes in the liver. These findings might be of clinical benefit in deciding the administration time and doses of anesthetics.

Animals↗
PubMed2005

Overweight is associated with allergy in school children of Taiwan and Vietnam but not Japan.

We collected information concerning diagnosed allergy from 2027 school children in Japan, Taiwan and Vietnam. Children were classified according to the age and sex-specific body mass index (BMI) per-age as indicator of weight status. Logistic regression was performed to examine the relationship between percentiles of BMI-per-age and allergy. Compared with children at the lowest percentile group Taiwanese children at > 85th percentile group showed a tendency toward higher risk of allergy (OR = 1.79, 95% CI 0.98 to 3.27; p = 0.060). When children with rhino-conjunctivitis were excluded from the analysis the association reached statistical significance (OR = 2.89, 95% CI 1.08 to 7.75; p = 0.035). Vietnamese children at > 85th percentile group showed a significantly higher risk of allergy (OR = 2.34, 95% CI 1.06 to 5.17; p = 0.035). This association was not observed when children with atopic dermatitis or food allergy were excluded from the analysis, although a tendency toward increased risk of allergy at BMI-per-age > 85th percentile remained. Our study sample of Japanese school children showed no association between being overweight and allergy.

Adolescent↗
PubMed2005

Testosterone-dependent transgene expression in the liver of the CAG-lacZ transgenic rat.

Many endogenous gene expressions in the liver are well known to be predominant in males, compared with those of females. In contrast, the fate of hepatic transgene expression between sexes is not fully understood. Here we studied whether sex hormones changed hepatic transgene expression in the ubiquitous CAG promoter-driven lacZ transgenic (Tg) rat. Both sexes of CAG-lacZ Tg rats received gonadectomy. Liver biopsy was taken weekly to determine the change of transgene expression. Histological result of adult males showed mosaic lacZ expression but it was negative in adult females, while livers in neonatal stage showed comparable expression of lacZ. Other organs exhibited equal expression in both sexes. At 2 weeks after castration, lacZ expression in male liver was significantly decreased and became negative after 4 weeks while no significant difference was observed in the lacZ expression pattern in other organs. After ovariectomy, lacZ expression in female liver remained undetectable. Moreover, testosterone treatment to gonadectomized rats of both sexes could enhance lacZ expression in the liver. In summary, we report that CAG-lacZ Tg rats demonstrate sexual dimorphism of transgene expression specifically only in the liver. Testosterone administration mediated upregulation of liver lacZ expression. Our findings suggested that androgen, especially testosterone, plays an important role in the hepatic transgene expression.

Animals↗
PubMed2005

[Surveillance of susceptibility of clinical isolates to panipenem between 2000 and 2003].

For the post-marketing surveillance of panipenem/betamipron (PAPM/BP, Carbenin), MICs of injectable beta-lactam antibacterials including PAPM against clinical isolates from 15 medical institutions all over Japan are measured yearly and the incidence rates of resistance in various species are also evaluated. In the first surveillance from June 2000 to March 2001, 1,356 isolates of 28 species were tested, 1,221 isolates of the same 28 species were tested in the second surveillance from April 2001 to March 2002, and 1,403 isolates of the same 28 species were tested in the third surveillance from April 2002 to March 2003. No remarkable changes in the activity of PAPM were observed in these surveillances spanning three years. The activity of PAPM in this study was comparable to that in the studies conducted before Carbenin was launched. This result suggests that PAPM still maintains potent activity. In these surveillances spanning three years, the incidence rates of resistance in various species were as follows (2000.6-2001.3 --> 2001.4-2002.3 --> 2002.4-2003.3): methicillin-resistant Staphylococcus aureus (39.3% --> 43.9% --> 47.3%), penicillin-intermediate Streptococcus pneumoniae (48.9% --> 44.2% --> 25.7%), penicillin-resistant S. pneumoniae (PRSP, 13.8% --> 26.3% --> 43.2%), extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (0.9% --> 0% --> 1.4%), ESBL-producing Klebsiella pneumoniae (3.4% --> 1.3% --> 3.1%), beta-lactamase-producing Haemophilus influenzae (19.2% --> 8.9% --> 42.9%), beta-lactamase-negative ampicillin-resistant H. influenzae (BLNAR, 22.1% --> 30.7% --> 33.0%), and metallo-beta-lactamase-producing Pseudomonas aeruginosa (1.0% --> 4.4% --> 1.0%). PAPM showed the most potent activity among tested drugs against PRSP, whose incidence rate increased notably. BLNAR, whose incidence rates also increased, exhibited low susceptibility to all tested drugs and metallo-beta-lactamase-producing P. aeruginosa also exhibited high resistance. The findings of this surveillance indicate that it is necessary to pay careful attention to the trends of resistant bacteria such as PRSP, BLNAR, and metallo-beta-lactamase producing strains.

Adolescent↗