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81.
Phenotypic abnormalities observed in aged cloned mice from embryonic stem cells after long-term maintenance 总被引:1,自引:0,他引:1
Shimozawa N Sotomaru Y Eguchi N Suzuki S Hioki K Usui T Kono T Ito M 《Reproduction (Cambridge, England)》2006,132(3):435-441
Somatic/embryonic stem cell cloning has made it possible to produce an individual genomically identical to another individual. However, the cloned animals have a variety of abnormalities caused by the aberrant gene modification, with insufficient reprogramming in cloning. We previously reported abnormalities in cloned mice at birth. In this study, we examined what abnormalities could be seen in cloned mice after long-term maintenance. The aged cloned mice showed multiple abnormalities: increase of body weight, some phenotypic abnormalities in the kidneys, testes and thymus, and lower urea nitrogen in their serum biochemical values. The kidneys of all cloned mice were hypertrophied, with a metamorphic or whitish appearance. The multiple lesions, including the enlarged renal pelvis and distension of the renal veins in histology, might be the result of urine accumulation by urinary tract obstruction. The testes of the cloned mice were atrophied, and showed no sperm formation in histology. In contrast, the thymus was rather hypertrophied, and a comparably increased number of lymphocytes were observed in the medulla, consisting mainly of T cells. By conducting a progeny test between the cloned mice, it was confirmed that these abnormalities in the aged cloned mice were not transmitted to their offspring, indicating that the incomplete reprogramming in clones might be in part responsible for the abnormalities detected in aged clones. These results indicate that the postnatal abnormalities observed in aged cloned mice are varied and can be restored through the germ line. 相似文献
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Shu ZhangCheng Lu Nobuhiko TakeichiTetsu Kiyobayashi Nobuhiro Kuriyama 《International Journal of Hydrogen Energy》2011,36(1):634-638
In order to understand the final state of the TiCl3 dopant during the dehydrogenation and rehydrogenation cycles of NaAlH4, we determined the reaction stoichiometry between TiCl3 and NaAlH4 by measuring the amount of hydrogen evolution from NaAlH4 with the varying TiCl3 -load. We found that: (i) TiCl3 reacted with 3 M equivalents of NaAlH4 during the doping process of ball-milling, (ii) the Ti dopant continued to react with NaAlH4 during the first dehydrogenation process until total six equivalents of NaAlH4 were consumed, and (iii) Ti fixed Al, not NaH, so that Al became insufficient during the rehydrogenation process. These findings lead to the conclusion that the reaction stoichiometry between Ti and Al is 1:6, which probably yields TiAl6 and plays a catalytic role in the hydrogen storage reactions of Ti-doped NaAlH4. 相似文献
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Hamidreza Koohdar Mahmoud Nili-Ahmadabadi Mohammad Habibi-Parsa Hamid Reza Jafarian Tilak Bhattacharjee Nobuhiro Tsuji 《Metallurgical and Materials Transactions A》2017,48(11):5244-5257
The stability of reversely formed austenite and related mechanism of transformation were investigated against temperature and time in an Fe-9.6Ni-7.1Mn (at. pct) martensitic steel during intercritical annealing at a dual-phase (α + γ) region. Dilatometry, electron backscattering diffraction (EBSD), atom probe tomography (APT), and X-ray diffraction (XRD) were used to characterize the mechanism of reverse transformation. It was found that under intercritical annealing at 853 K (580 °C), when the heating rate is 20 K/s (20 °C/s), reverse transformation takes place through a mixed diffusion control mechanism, i.e., controlled by bulk diffusion and diffusion along the interface, where Ni controls the diffusion as its diffusivity is lower than that of Mn in the martensite and austenite. Increasing the intercritical annealing to 873 K (600 °C) at an identical heating rate of 20 K/s (20 °C/s) showed that reverse transformation occurs through a sequential combination of both martensitic and diffusional mechanisms. The transition temperature from diffusional to martensitic transformation was obtained close to 858 K (585 °C). Experimental results revealed that the austenite formed by the diffusional mechanism at 853 K (580 °C) mainly remains untransformed after cooling to ambient temperature due to the enrichment with Ni and Mn. It was also found that the stability of the reversely formed austenite by martensitic mechanism at 873 K (600 °C) is related to grain refinement. 相似文献
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Helicobacter pylori Disrupts Host Cell Membranes, Initiating a Repair Response and Cell Proliferation 总被引:1,自引:0,他引:1
LL Lin HC Huang S Ogihara JT Wang MC Wu PL McNeil CN Chen HF Juan 《International journal of molecular sciences》2012,13(8):10176-10192
Helicobacter pylori (H. pylori), the human stomach pathogen, lives on the inner surface of the stomach and causes chronic gastritis, peptic ulcer, and gastric cancer. Plasma membrane repair response is a matter of life and death for human cells against physical and biological damage. We here test the hypothesis that H. pylori also causes plasma membrane disruption injury, and that not only a membrane repair response but also a cell proliferation response are thereby activated. Vacuolating cytotoxin A (VacA) and cytotoxin-associated gene A (CagA) have been considered to be major H. pylori virulence factors. Gastric cancer cells were infected with H. pylori wild type (vacA+/cagA+), single mutant (ΔvacA or ΔcagA) or double mutant (ΔvacA/ΔcagA) strains and plasma membrane disruption events and consequent activation of membrane repair components monitored. H. pylori disrupts the host cell plasma membrane, allowing localized dye and extracellular Ca(2+) influx. Ca(2+)-triggered members of the annexin family, A1 and A4, translocate, in response to injury, to the plasma membrane, and cell surface expression of an exocytotic maker of repair, LAMP-2, increases. Additional forms of plasma membrane disruption, unrelated to H. pylori exposure, also promote host cell proliferation. We propose that H. pylori activation of a plasma membrane repair is pro-proliferative. This study might therefore provide new insight into potential mechanisms of H. pylori-induced gastric carcinogenesis. 相似文献
90.
Mechanisms Underlying Decreased Hepatic Triacylglycerol and Cholesterol by Dietary Bitter Melon Extract in the Rat 总被引:4,自引:0,他引:4
Senanayake GV Fukuda N Nshizono S Wang YM Nagao K Yanagita T Iwamoto M Ohta H 《Lipids》2012,47(5):495-503
In these studies, we focused on finding the mechanism(s) underlying the bitter melon (Momordica charantia L.) methanol fraction (MF)-dependent reduction in the concentration of hepatic triacylglycerol (TAG) and cholesterol in the
rat. Rats were fed diets containing low (5 %) fat for 2 weeks (experiment 1), or low (5 %) and high (15 %) fat for a longer
period of 8 weeks (experiment 2). MF was supplemented at 1 % level in both experiments. After feeding, rats were sacrificed,
and their livers were prepared as slices and hepatocytes, followed by incubation with [1(2)-14C] acetate or [1-14C] oleic acid (18:1 n-6). Under these conditions, we found that rats fed diets containing MF, as compared to those without
MF, showed: (1) no adverse effects on food intake and growth, (2) a decreased hepatic TAG and total cholesterol, irrespective
of the difference in dietary fat level or feeding period, and (3) a decreased incorporation of [1(2)-14C] acetate and [1-14C] oleic acid into TAG of liver slices and hepatocytes. MF-supplemented rats also showed no altered incorporation of labeled
acetate into cholesterol and cholesterol ester, an increased fecal excretion of neutral steroids, but not of acidic steroids,
and an enhanced mRNA abundance of carnitine palmitoylacyltransferase I, which is the rate-limiting enzyme for fatty acid oxidation.
These results suggest that dietary MF decreases hepatic TAG synthesis while enhancing fatty acid oxidation, thereby reducing
the concentration of hepatic TAG. The liver cholesterol-lowering effect of MF, however, is probably mediated through an increased
fecal excretion of neutral steroids, without an effect on cholesterogenesis. 相似文献