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971.
Tetsuya Sakashita Nobuyuki Hamada Isao Kawaguchi Noriyuki B. Ouchi Takamitsu Hara Yasuhiko Kobayashi Kimiaki Saito 《PloS one》2013,8(7)
Background
Clonogenicity gives important information about the cellular reproductive potential following ionizing irradiation, but an abortive colony that fails to continue to grow remains poorly characterized. It was recently reported that the fraction of abortive colonies increases with increasing dose. Thus, we set out to investigate the production kinetics of abortive colonies using a model of branching processes.Methodology/Principal Findings
We firstly plotted the experimentally determined colony size distribution of abortive colonies in irradiated normal human fibroblasts, and found the linear relationship on the log-linear or log-log plot. By applying the simple model of branching processes to the linear relationship, we found the persistent reproductive cell death (RCD) over several generations following irradiation. To verify the estimated probability of RCD, abortive colony size distribution (≤15 cells) and the surviving fraction were simulated by the Monte Carlo computational approach for colony expansion. Parameters estimated from the log-log fit demonstrated the good performance in both simulations than those from the log-linear fit. Radiation-induced RCD, i.e. excess probability, lasted over 16 generations and mainly consisted of two components in the early (<3 generations) and late phases. Intriguingly, the survival curve was sensitive to the excess probability over 5 generations, whereas abortive colony size distribution was robust against it. These results suggest that, whereas short-term RCD is critical to the abortive colony size distribution, long-lasting RCD is important for the dose response of the surviving fraction.Conclusions/Significance
Our present model provides a single framework for understanding the behavior of primary cell colonies in culture following irradiation. 相似文献972.
Naoki Makita Sung Won Choi Arihiro Kano Asako Yamayoshi Toshihiro Akaike Atsushi Maruyama 《Nucleosides, nucleotides & nucleic acids》2013,32(8-9):1115-1119
Cationic comb-type copolymer (CCC) consisting of a polycationic backbone and abundant graft water-soluble chains exhibited considerable stabilization effect on DNA hybrids, such as double- and triple-stranded DNAs. Here, we describe the effect of CCC on antiparallel G-quadruplex folding of human telomeric DNA, d(GGGTTA) n in the presence of sodium ions. CCC did not significantly alter the circular dichroism (CD) spectra of d((GGGTTA) 3 GGG) and d((GGGTTA)7GGG) indicating that the CCC did not influence the antiparallel folding of the telomeric repeats. Hence, the ionic interaction of CCC with the DNA sequence did not interfere with specific interaction of the DNA with sodium ions to form G-quartets. Interestingly, CCC did not change the melting temperature of the d((GGGTTA) 3 GGG) suggesting negligible stabilizing effect of CCC on the antiparallel quadruplex structure. 相似文献
973.
Tokumi Maruyama Yoshiko Sato Takeshi Goto Mitsutoshi Fukuhara 《Nucleosides, nucleotides & nucleic acids》2013,32(7-9):1079-1082
Abstract 2′,3′,5′-Tri-O(tetrahydropyran-2-yl)inosine 1 was treated with iodobenzene or 2-bromopyridine in the presence of cuprous oxide in pyridines to give the N1 -aryl derivatives 2a, b. Deprotection of the products afforded N1 -arylinosines 3a, b. 相似文献
974.
975.
Osamu Noyori Eri Nakayama Junki Maruyama Reiko Yoshida Ayato Takada 《Biochemical and biophysical research communications》2013
Apoptotic death of virus-infected cells is generally thought to be a defense mechanism to limit the spread of infectious virions by eliminating virus-producing cells in host animals. On the other hand, several viruses have been shown to have anti-apoptotic mechanisms to facilitate efficient viral replication and transmission. In this study, we found that the filovirus glycoprotein (GP) expressed on cell surfaces formed a steric shield over the Fas molecule and that GP-expressing cells showed resistance to cell death induced by a Fas agonistic antibody. These results suggest that filovirus GP-mediated steric shielding may interfere with the Fas-induced apoptotic signal transduction in infected cells and serve as an immune evasion mechanism for filoviruses. 相似文献
976.
977.
Ai Minomo Yu Ishima Victor T.G. Chuang Yoshiaki Suwa Ulrich Kragh-Hansen Toru Narisoko Hiroshi Morioka Toru Maruyama Masaki Otagiri 《Biochimica et Biophysica Acta (BBA)/General Subjects》2013
Background
4Z,15Z-bilirubin-IXα (BR), an endogenous toxic compound that is sparingly soluble in water, binds human serum albumin (HSA) with high affinity in a flexible manner. Our previous findings suggest that both Lys195 and Lys199 in subdomain IIA are important for the high-affinity binding of BR, and especially Lys199 in stand-alone domain II plays a prominent role in the renal elimination of BR. Our hypothesis is that HSA-domain II with high BR binding would be a useful therapeutic agent to treat hyperbilirubinemia in patients with impaired liver function.Methods
Unbound BR concentrations were determined using a modified HRP assay. To evaluate the effect of pan3_3-13 domain II mutant in promoting urinary BR excretion, the serum concentration and urinary excretion amount of BR were determined using bile duct ligation mice.Results
After three or six rounds of panning, pan3_3-13 and pan6_4 were found to have a significantly higher affinity for BR than wild-type domain II. Administration of pan3_3-13 significantly reduced serum BR level and increased its urinary excretion in the disease model mice as compared to wild-type domain II treatment.Conclusions
These results suggest that pan3_3-13 has great potential as a therapeutic agent that promotes urinary BR excretion in hyperbilirubinemia.General significance
This is the first study to be applied to other HSA bound toxic compounds that are responsible for the progression of disease, thereby paving the way for the development of non-invasive and cost effective blood purification treatment methods. 相似文献978.
Yoshiki Sakata Hiromasa Maruyama Kuniharu Takenouchi 《Bioscience, biotechnology, and biochemistry》2013,77(2):133-142
The β-crystal formation of l-glutamic acid in the seeded solution was investigated; and it was found that the growth rate of the seed crystals in a-axis direction was nearly as large as that of the α-crystal, but the growth rate in b- and c-axes was little recognized. The activation energy of the crystallization process of the β-crystal in a-axis direction was calculated from the growth rate constants determined at various temperatures, and 6~7 kcal/mol was obtained. On the assumption that the crystallization of β-crystal growth was controlled by the diffusional operation, the thickness of the laminar film was calculated from the growth rate constant and the estimated value of the diffusional constant. The calculated value of the thickness was much greater than the value reported by Nernst; therefore, the crystallization process should be controlled by the surface reaction. The co-existence of a small quantity of amino acids caused a great reduction in the growth rate of the β-crystal. 相似文献
979.
Goro Kato Yoshiharu Maruyama Michinori Nakamura 《Bioscience, biotechnology, and biochemistry》2013,77(12):2843-2855
Phase-contrast and fluorescence microscopy observations showed that pea symbiont R. leguminosarum adsorbed to pea root hairs, but non-symbiont rhizobial strains only adsorbed to a small extent. 14C-labeled cells were used to assay the number of rhizobial cells adsorbed to a pea root. Capsular polysaccharides or lipopolysaccharides obtained from R. leguminosarum specifically inhibited the adsorption of 14C-R. leguminosarum cells to a pea root and specifically adsorbed to pea root hairs. Also, they reacted specifically with pea seed lectins. These results suggest that capsular polysaccharides or lipopolysaccharides play an important role in host-specific adsorption. The interaction between the polysaccharides and pea lectins could be the key to determining host specificity in the infection process of Rhizobium-pea symbiosis. 相似文献
980.
Shigeo Tamaki Jun-ichi Nakagawa Ichiro N. Maruyama Michio Matsuhashi 《Bioscience, biotechnology, and biochemistry》2013,77(11):2147-2150
Escherichia coli cells acquired supersensitivity to various β-lactam antibiotics by dacA mutation, a defect in D-alanine carboxypeptidase IA activity. The mutant cells were rather less sensitive to mecillinam than the dacA+ cells. This mutation did not result in either thermosensitivity of cell growth or appreciable increase of the generation times in usual rich media, but the resulting appearance of supersensitivity to β-lactam antibiotics suggests that the cell wall or envelope of this mutant is somewhat abnormal and thus that D-alanine carboxypeptidase IA is involved in cell wall or envelope synthesis. 相似文献