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991.
Yuichiro Higuchi Kenji Kawai Masahumi Yamamoto Miyuki Kuronuma Yasuhiko Ando Ikumi Katano Masato Nakamura Hiroshi Suemizu 《Experimental Animals》2014,63(1):55-62
The interaction between transplanted cells and host tissues is important for the growth
and maintenance of transplanted cells. To analyze the mechanisms of these interactions, a
systemic fluorescent protein-expressing mouse is a useful recipient. In this study, we
generated a novel NOG strain, which strongly expresses enhanced green fluorescent protein
(EGFP; PgkEGFP-NOG), especially in the liver, kidney, gastrointestinal tract, and testis.
Because the host tissues expressed EGFP, xenotransplanted human cancer cells were clearly
identified as EGFP-negative colonies in PgkEGFP-NOG mice. Immunohistochemical analysis
revealed that EGFP-expressing stromal tissues formed a complicated tumor microenvironment
within xenograft tissues. Moreover, a similar microenvironment was observed in human iPS
cell-derived teratomas. Collectively, these results indicated that a suitable
microenvironment is essential for the growth and maintenance of xenotransplanted cells and
that PgkEGFP-NOG mice represent a useful animal model for analyzing the mechanisms of
microenvironment formation. 相似文献
992.
Michael Ionescu Clelia Baccari Aline Maria Da Silva Angelica Garcia Kenji Yokota Steven E. Lindow 《Journal of bacteriology》2013,195(23):5273-5284
Xylella fastidiosa, like related Xanthomonas species, employs an Rpf cell-cell communication system consisting of a diffusible signal factor (DSF) synthase, RpfF, and a DSF sensor, RpfC, to coordinate expression of virulence genes. While phenotypes of a ΔrpfF strain in Xanthomonas campestris could be complemented by its own DSF, the DSF produced by X. fastidiosa (XfDSF) did not restore expression of the XfDSF-dependent genes hxfA and hxfB to a ΔrpfF strain of X. fastidiosa, suggesting that RpfF is involved in XfDSF sensing or XfDSF-dependent signaling. To test this conjecture, rpfC and rpfF of X. campestris were replaced by those of X. fastidiosa, and the contribution of each gene to the induction of a X. campestris DSF-dependent gene was assessed. As in X. fastidiosa, XfDSF-dependent signaling required both X. fastidiosa proteins RpfF and RpfC. RpfF repressed RpfC signaling activity, which in turn was derepressed by XfDSF. A mutated X. fastidiosa RpfF protein with two substitutions of glutamate to alanine in its active site was incapable of XfDSF production yet enabled a response to XfDSF, indicating that XfDSF production and the response to XfDSF are two separate functions in which RpfF is involved. This mutant was also hypervirulent to grape, demonstrating the antivirulence effects of XfDSF itself in X. fastidiosa. The Rpf system of X. fastidiosa is thus a novel example of a quorum-sensing signal synthase that is also involved in the response to the signal molecule that it synthesizes. 相似文献
993.
Kenji Kawanaka 《Primates; journal of primatology》1989,30(3):285-305
The behavior and social interactions of young male chimpanzees were studied in relation to their age change. The data were
obtained at the Mahale Mountains National Park, during a four-month period in 1986. Early adolescent males, becoming independent
of their mothers, spend a long time near adults of both sexes. Late adolescent males are not tolerated by the senior males.
Although such animals do not stop traveling together with their seniors, they are separated from the other members including
the males of their own age class, and each of them lives a relatively lonely life. Where seniors are not nearby, they perform
charging displays in front of estrous females. Young adult males tend to remain in the proximity of the alpha male, and can
associate with their seniors without pant-grunting. Although some young adult males dominate over some senior males, increasingly
performing charging displays, they do not appear to be permitted to associate intimately with their seniors; they are not
yet considered to have attained social maturity. Prime and senior males are strongly bonded with one another, being able to
associate intimately with those of their own or senior age classes including the alpha male. A young adult male's rise in
rank is not connected with joining the “adult male-cluster,” nor does a senior male's decline necessarily means his dropping
out from the cluster: the social position of male chimpanzees cannot be understood solely from their agonistic dominance rank.
The alpha male plays a leading part in integrating the males of the unit-group. Young adult males and their seniors tend to
associate most frequently with him, and all the males of the early adolescent or senior age classes pay attention to his movements. 相似文献
994.
995.
Yuko Hisatomi Kyo Asakura Kenji Kugino Mamoru Kurokawa Tomiko Asakura Keiko Nakata 《PloS one》2013,8(11)
In humans, emaciation from long-term dietary deficiencies, such as anorexia, reportedly increases physical activity and brain atrophy. However, the effects of single short-term fasting on brain tissue or behavioral activity patterns remain unclear. To clarify the impact of malnutrition on brain function, we conducted a single short-term fasting study as an anorexia model using male adult mice and determined if changes occurred in migratory behavior as an expression of brain function and in brain tissue structure. Sixteen-week-old C57BL/6J male mice were divided into either the fasted group or the control group. Experiments were conducted in a fixed indoor environment. We examined the effects of fasting on the number of nerve cells, structural changes in the myelin and axon density, and brain atrophy. For behavior observation, the amount of food and water consumed, ingestion time, and the pattern of movement were measured using a time-recording system. The fasted mice showed a significant increase in physical activity and their rhythm of movement was disturbed. Since the brain was in an abnormal state after fasting, mice that were normally active during the night became active regardless of day or night and performed strenuous exercise at a high frequency. The brain weight did not change by a fast, and brain atrophy was not observed. Although no textural change was apparent by fasting, the neuronal neogenesis in the subventricular zone and hippocampus was inhibited, causing disorder of the brain function. A clear association between the suppression of encephalic neuropoiesis and overactivity was not established. However, it is interesting that the results of this study suggest that single short-term fasting has an effect on encephalic neuropoiesis. 相似文献
996.
Kenji Doi Akemi Doi Takeshi Ozaki Toshio Fukui 《Bioscience, biotechnology, and biochemistry》2013,77(7):1629-1633
The action pattern of lytic β-1,3 glucanase (glucanase I) from Arthrobacter which liberates predominantly laminaripentaose from various β-glucans has been studied. The enzyme was not active on short linear laminaridextrins, but was active on an enzymatically synthesized, linear β-1,3 oligoglucan preparation. Any intactness of the glucose residues of the chain ends of a substrate did not seem to be necessary for the action of the enzyme. The results of determination of laminaripentaose during a relatively early phase of the reaction suggested that about half of the reducing power liberated in the medium might be explained by the formation of the sugar. It seems that the formation of laminaripentaose relates to the initial attack of glucanase 1 on β-1,3 glucan chains. 相似文献
997.
Kenji Mori 《Bioscience, biotechnology, and biochemistry》2013,77(10):2045-2047
A key intermediate, 2-isocyano-3-hydroxybutyrate (III) was isolated from a reaction of isocyanoacetate (I) with acetaldehyde (II) in the presence of Et3N. It was found that III was readily converted into 2-isocyanocrotonate (V) and 2-isocyano-2-(1′-hydroxyethyl)-3-hydroxybutyrate (VI) which are undesirable compounds for the synthesis of threonine. However, by use of a metal catalyst (e.g. NiCl2 or PdCl2), the isocyano-hydroxy compound (III) was selectively converted into 5-methyl-4-alkoxycarbonyl-2-oxazoline (IV) which is an important precursor of threonine. Furthermore, chemical properties of IV were examined; the results suggested that cis-oxazoline was relatively sensitive to acid, base and heat.On the basis of these results, the reaction of I with II was carried out using Et3N-PdCl2 as a catalyst to obtain threo-threonine (85% purity) in a good yield (85%). 相似文献
998.
999.
1000.
Kenji Yamashita Michio Motohashi Takatsuka Yashiki 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1991,570(2):329-338
Column-switching techniques for high-performance liquid chromatography of two acidic drugs, ibuprofen and mefenamic acid, in human serum with short-wavelength ultraviolet detection are described. The method involved extraction of the analyte from acidified serum followed by the chromatographic analysis using column switching. Three ODS columns were used each with different mobile phase, utilizing the difference of ion-pair formation or of ionization caused by pH change. The method offered high sensitivity and selectivity, with short-wavelength ultraviolet detection at 221 nm for ibuprofen and at 219 nm for mefenamic acid. The detection limits were 0.5 ng/ml (2.4 pmol/ml) for ibuprofen and 0.1 ng/ml (0.4 pmol/ml) for mefenamic acid using 1 ml of serum, both at a signal-to-noise ratio of 3. With some modifications, the principle of the method would be applicable to other acidic compounds in biological fluids. 相似文献