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31.
LQ Jia M Osada C Ishioka M Gamo S Ikawa T Suzuki H Shimodaira T Niitani T Kudo M Akiyama N Kimura M Matsuo H Mizusawa N Tanaka H Koyama M Namba R Kanamaru T Kuroki 《Canadian Metallurgical Quarterly》1997,19(4):243-253
We have screened the p53 status of 156 human cell lines, including 142 tumor cell lines from 27 different tumor types and 14 cell lines from normal tissues by using functional analysis of separated alleles in yeast. This assay enables us to score wild-type p53 expression on the basis of the ability of expressed p53 to transactivate the reporter gene HIS3 via the p53-responsive GAL1 promotor in Saccharomyces cerevisiae. Of 142 tumor cell lines, at least 104 lines (73.2%) were found to express the mutated p53 gene: 94 lines (66.2%) were mutated in both alleles, three lines (2.1%) were heterozygous, and no p53 cDNA was amplified from seven lines (4.9%). Of the 14 cell lines originating from normal tissues, all the transformed or immortalized cell lines expressed mutant p53 only. Yeast cells expressing mutant p53 derived from 94 cell lines were analyzed for temperature-sensitive growth. p53 cDNA from eight cell lines showed p53-dependent temperature-sensitive growth, growing at 30 degrees C but not at 37 degrees C. Four temperature-sensitive p53 mutations were isolated: CAT-->CGT at codon 214 (H214R), TAC-->TGC at codon 234 (Y234C), GTG-->ATG at codon 272 (V272M), and GAG-->AAG (E285K). Functionally wild-type p53 was detected in 38 tumor cell lines (26.8%) and all of the diploid fibroblasts at early and late population doubling levels. These results strongly support the previous findings that p53 inactivation is one of the most frequent genetic events that occurs during carcinogenesis and immortalization. 相似文献
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K Iida K Fujita H Hirai H Goto S Miyazaki Y Arai H Iwaki M Otake S Sassa M Maemura T Nakayama H Kudo S Sakamoto 《Canadian Metallurgical Quarterly》1997,21(5):476-482
Polysaccharides extracted from human tubercle bacilli (specific substance of Maruyama [SSM]) have been clinically applied with satisfactory results. Thymidylate synthetase (TS) and thymidine kinase (TK) are key enzymes in de novo and salvage pathways for pyrimidine nucleotide synthesis. Well- and moderately well differentiated adenocarcinomas induced with 1,2-dimethylhydrazine (DMH) are widely distributed throughout the colorectal tract with high TK activity, and the poorly differentiated type is mainly restricted in the proximal colon and the cecum with high TS activity in rats. Subcutaneously injecting the rats with SSM reduced TS activity in colonic nontumorous regions, but in the tumorous regions it reduced TK activity compared with that of the DMH-treated rats without SSM treatment. SSM is suggested to reduce the colorectal carcinogenesis induced with DMH by inhibiting DNA synthesis in a de novo pathway, and to suppress the development of the tumors by decreasing DNA synthesis in the salvage pathway in rats. 相似文献
34.
Acetylcholinesterase (AChE) and calbindin D-28K (CaBP) are transiently expressed in the rat auditory nuclei during the early postnatal period. In the ventral division of the medial geniculate body (MGV), the transient AChE expression in the neuropil is replaced by CaBP expression in the neurones. The time correlation between the up- and down-regulations in these neuro-chemicals suggests some switching over mechanism. A lesion of the inferior colliculus (IC) decreases the AChE reactivity in terminal field of the IC-MGV projections. We here demonstrate that the IC lesion results in CaBP expressions in neurones of the MGV before its normal onset. It is thus possible that the transiently expressed AChE plays an important role in the intercellular signal transduction for neurochemical phenotype expressions. 相似文献
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T Koshino S Takano T Houjo Y Sano K Kudo H Kihara S Kitani T Takaishi K Hirai K Ito Y Morita 《Canadian Metallurgical Quarterly》1998,247(2):510-513
Hormone-sensitive lipase (HSL) catalyzes the rate-limiting step in adipocyte lipolysis. We have studied the effect of glucose and long chain fatty acids on the HSL mRNA content of 3T3-F442A adipocytes. Exposure of the cells for 32 h to a medium without glucose led to a decrease by a factor of 2.5-3 in the HSL mRNA without a change in C/EBP alpha mRNA or triglyceride content of the adipocytes. The reduction in HSL mRNA level was accompanied by a decrease in HSL total activity. The effect of glucose exposure was observed after 24 h of exposure and was reversible. Treatment of the adipocytes with oleate did not affect HSL expression. These data show that glucose modulates HSL gene expression and hence could participate in the regulation of adipose tissue lipolysis. 相似文献
37.
Photocatalytic water splitting into H2 and O2 over various tantalates was reviewed and factors affecting photocatalytic activities of tantalates were discussed from a viewpoint of the crystal structure and the energy structure. Many tantalates, K3Ta3Si2O13, alkali and alkaline earth tantalates, were highly active photocatalysts for water splitting. The high activities were mainly due to the high conduction band level consisting of Ta5d orbitals. NiO-loaded NaTaO3 with the distorted perovskite structure showed the highest activity among tantalates. Moreover, the activity of the NiO/NaTaO3 photocatalyst was remarkably improved by doping of lanthanoids. The apparent quantum yield of NiO/NaTaO3 doped with lanthanum was ca. 50% at 270 nm. 相似文献
38.
Kudo Kazutoshi; Park Hyeonsaeng; Kay Bruce A.; Turvey M. T. 《Canadian Metallurgical Quarterly》2006,32(3):599
A simple instance of coupling behavior to the environment is oscillating the hands in pace with metronome beats. This environmental coupling can be weaker (1 beat per cycle) or stronger (2 beats per cycle). The authors examined whether strength of environmental coupling enhanced the stability of in-phase bimanual coordination. Detuning by manipulanda that produced different left and right eigenfrequencies shifted the relative phase angle from 0°, with the size of the shift larger for higher movement frequencies. Stronger environmental coupling was found to decrease this relative-phase shift, with accompanying increase and reduction, respectively, in recurrence quantification measures related to coordination stability and coordination noise. Stronger environmental coupling also increased oscillation amplitude. Results are considered from the perspective of parametric stabilization. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
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The pulse height distribution in 3He proportional counters has been investigated to accurately quantify the response function to be used in fast neutron spectroscopy. The measurements were performed as a function of the operating voltage, the counting gas mixture, and the incident neutron energy. The special emphasis of this study has been put on the nonlinearity of the pulse height of a recoil helium induced by the 3He(n,n)3He reaction. A distinct deviation of 14% at maximum to lower energies was found in the position of the recoil edge with the energy axis calibrated by the full energy peaks of the 3He(n,p)T reaction produced with neutrons of thermal energy and 2.413 MeV. It was confirmed that the nonlinear effects, such as an initial recombination and a space-charge effect, take place more significantly in the energy loss process of a recoil helium because of its higher linear energy transfer (LET) in the filling gas compared to that of a proton and triton pair emitted from the 3 He(n,p)T reaction. The deviation becomes larger with an increase of the average LET in the gas mixture. The experimental results suggested that the nonlinear effect caused by a higher LET recoil helium is inevitable for the filling gas, even if the operating voltage is changed to an acceptable range 相似文献