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排序方式: 共有2031条查询结果,搜索用时 171 毫秒
971.
Andreyan N. Osipov Anna Grekhova Margarita Pustovalova Ivan V. Ozerov Petr Eremin Natalia Vorobyeva Natalia Lazareva Andrey Pulin Alex Zhavoronkov Sergey Roumiantsev Dmitry Klokov Ilya Eremin 《Oncotarget》2015,6(29):26876-26885
Molecular and cellular responses to protracted ionizing radiation exposures are poorly understood. Using immunofluorescence microscopy, we studied the kinetics of DNA repair foci formation in normal human fibroblasts exposed to X-rays at a dose rate of 4.5 mGy/min for up to 6 h. We showed that both the number of γH2AX foci and their integral fluorescence intensity grew linearly with time of irradiation up to 2 h. A plateau was observed between 2 and 6 h of exposure, indicating a state of balance between formation and repair of DNA double-strand breaks. In contrast, the number and intensity of foci formed by homologous recombination protein RAD51 demonstrated a continuous increase during 6 h of irradiation. We further showed that the enhancement of the homologous recombination repair was not due to redistribution of cell cycle phases. Our results indicate that continuous irradiation of normal human cells triggers DNA repair responses that are different from those elicited after acute irradiation. The observed activation of the error-free homologous recombination DNA double-strand break repair pathway suggests compensatory adaptive mechanisms that may help alleviate long-term biological consequences and could potentially be utilized both in radiation protection and medical practices. 相似文献
972.
Andreyan N. Osipov Margarita Pustovalova Anna Grekhova Petr Eremin Natalia Vorobyova Andrey Pulin Alex Zhavoronkov Sergey Roumiantsev Dmitry Y. Klokov Ilya Eremin 《Oncotarget》2015,6(29):27275-27287
Diagnostic imaging delivering low doses of radiation often accompany human mesenchymal stem cells (MSCs)-based therapies. However, effects of low dose radiation on MSCs are poorly characterized. Here we examine patterns of phosphorylated histone H2AX (γH2AX) and phospho-S1981 ATM (pATM) foci formation in human gingiva-derived MSCs exposed to X-rays in time-course and dose-response experiments. Both γH2AX and pATM foci accumulated linearly with dose early after irradiation (5–60 min), with a maximum induction observed at 30–60 min (37 ± 3 and 32 ± 3 foci/cell/Gy for γH2AX and pATM, respectively). The number of γH2AX foci produced by intermediate doses (160 and 250 mGy) significantly decreased (40–60%) between 60 and 240 min post-irradiation, indicating rejoining of DNA double-strand breaks. In contrast, γH2AX foci produced by low doses (20–80 mGy) did not change after 60 min. The number of pATM foci between 60 and 240 min decreased down to control values in a dose-independent manner. Similar kinetics was observed for pATM foci co-localized with γH2AX foci. Collectively, our results suggest differential DNA double-strand break signaling and processing in response to low vs. intermediate doses of X-rays in human MSCs. Furthermore, mechanisms governing the prolonged persistence of γH2AX foci in these cells appear to be ATM-independent. 相似文献
973.
Tatiana Zdobnova Evgeniya Sokolova Oleg Stremovskiy Dmitry Karpenko William Telford Ilya Turchin Irina Balalaeva Sergey Deyev 《Oncotarget》2015,6(31):30919-30928
We have created a novel fluorescent model of a human ovarian carcinoma xenograft overexpressing receptor HER2, a promising molecular target of solid tumors. The model is based on a newly generated SKOV-kat cell line stably expressing far-red fluorescent protein Katushka. Katushka is most suitable for the in vivo imaging due to an optimal combination of high brightness and emission in the “window of tissue transparency”. The relevance of the fluorescent model for the in vivo monitoring of tumor growth and response to treatment was demonstrated using a newly created HER2-targeted recombinant immunotoxin based on the 4D5scFv antibody and a fragment of the Pseudomonas exotoxin A. 相似文献
974.
975.
Hypothalamic-pituitary cytokine network 总被引:4,自引:0,他引:4
976.
Gomez-Daspet J Elko L Grebenev D Vesely DL 《The American journal of the medical sciences》2002,324(6):321-325
A 41-year-old woman who had undergone transfrontal craniotomy for a pituitary tumor 4 months before presentation was admitted with confusion and orientation only to self. She had a fever of 40 degrees C. Serum sodium and chloride levels on admission were 180 and 139 mEq/L, respectively. Measured serum osmolality was 380 mOsmol/L with a urine osmolality of 360 mOsmol/L. Magnetic resonance imaging revealed a 1.5-cm mass in the sella turcica, which was nonfunctioning on endocrine evaluation. The "bright spot" of a normal posterior pituitary was absent. Central diabetes insipidus was confirmed by a 300% increase in urine osmolality with desmopressin. The patient survived her severe hypernatremia, which has 70% mortality with a serum sodium level of 160 mEq/L or above. However, she developed permanent (6 months) disorientation to time and place even when hypernatremia was corrected, which has not been described previously. 相似文献
977.
Kseniia N. Grafskaia Azaliia F. Akhkiamova Dmitry V. Vashurkin Denis S. Kotlyarskiy Diego Pontoni Denis V. Anokhin Xiaomin Zhu Dimitri A. Ivanov 《Materials》2021,14(11)
We report on formation of a bicontinuous double gyroid phase by a wedge-shaped amphiphilic mesogen, pyridinium 4′-[3″,4″,5″-tris-(octyloxy)benzoyloxy]azobenzene-4-sulfonate. It is found that this compound can self-organize in zeolite-like structures adaptive to environmental conditions (e.g., temperature, humidity, solvent vapors). Depending on the type of the phase, the structure contains 1D, 2D, or 3D networks of nanometer-sized ion channels. Of particular interest are bicontinuous phases, such as the double gyroid phase, as they hold promise for applications in separation and energy. Specially designed environmental cells compatible with grazing-incidence X-ray scattering and atomic force microscopy enable simultaneous measurements of structural parameters/morphology during vapor-annealing treatment at different temperatures. Such in-situ approach allows finding the environmental conditions at which the double gyroid phase can be formed and provide insights on the supramolecular structure of thin films at different spatial levels. 相似文献
978.
Anna A. Ivanova Dina S. Syromotina Svetlana
N. Shkarina Roman Shkarin Angelica Cecilia Venera Weinhardt Tilo Baumbach Mariia S. Saveleva Dmitry A. Gorin Timothy E. L. Douglas Bogdan V. Parakhonskiy Andre G. Skirtach Pieter Cools Nathalie De Geyter Rino Morent C. Oehr Maria A. Surmeneva Roman A. Surmenev 《RSC advances》2018,8(68):39106
This article reports on a study of the mineralisation behaviour of CaCO3 deposited on electrospun poly(ε-caprolactone) (PCL) scaffolds preliminarily treated with low-temperature plasma. This work was aimed at developing an approach that improves the wettability and permeability of PCL scaffolds in order to obtain a superior composite coated with highly porous CaCO3, which is a prerequisite for biomedical scaffolds used for drug delivery. Since PCL is a synthetic polymer that lacks functional groups, plasma processing of PCL scaffolds in O2, NH3, and Ar atmospheres enables introduction of highly reactive chemical groups, which influence the interaction between organic and inorganic phases and govern the nucleation, crystal growth, particle morphology, and phase composition of the CaCO3 coating. Our studies showed that the plasma treatment induced the formation of O- and N-containing polar functional groups on the scaffold surface, which caused an increase in the PCL surface hydrophilicity. Mineralisation of the PCL scaffolds was performed by inducing precipitation of CaCO3 particles on the surface of polymer fibres from a mixture of CaCl2- and Na2CO3-saturated solutions. The presence of highly porous vaterite and nonporous calcite crystal phases in the obtained coating was established. Our findings confirmed that preferential growth of the vaterite phase occurred in the O2-plasma-treated PCL scaffold and that the coating formed on this scaffold was smoother and more homogenous than those formed on the untreated PCL scaffold and the Ar- and NH3-plasma-treated PCL scaffolds. A more detailed three-dimensional assessment of the penetration depth of CaCO3 into the PCL scaffold was performed by high-resolution micro-computed tomography. The assessment revealed that O2-plasma treatment of the PCL scaffold caused CaCO3 to nucleate and precipitate much deeper inside the porous structure. From our findings, we conclude that O2-plasma treatment is preferable for PCL scaffold surface modification from the viewpoint of use of the PCL/CaCO3 composite as a drug delivery platform for tissue engineering.This article reports on a study of the mineralisation behaviour of CaCO3 deposited on electrospun poly(ε-caprolactone) (PCL) scaffolds preliminarily treated with low-temperature plasma. 相似文献
979.
Dmitry Tumin David Drees Rebecca Miller Sharon Wrona Don Hayes Joseph D. Tobias Tarun Bhalla 《The journal of pain》2018,19(9):973-982
The population prevalence of pediatric chronic pain is not well characterized, in part because of a lack of nationally representative data. Previous research suggests that pediatric chronic pain prolongs inpatient stay and increases costs, but the population-level association between pediatric chronic pain and health care utilization is unclear. We use the 2016 National Survey of Children's Health to describe the prevalence of pediatric chronic pain, and compare health care utilization among children ages 0 to 17 years according to the presence of chronic pain. Using a sample of 43,712 children, we estimate the population prevalence of chronic pain to be 6%. In multivariable analysis, chronic pain was not associated with increased odds of primary care or mental health care use, but was associated with greater odds of using other specialty care (odds ratio [OR]?=?2.01, 95% confidence interval [CI] = 1.62–2.47; P?<?.001), complementary and alternative medicine (OR?=?2.32, 95% CI = 1.79–3.03; P?<?.001), and emergency care (OR?=?1.62, 95% CI = 1.29–2.02; P?<?.001). In this population-based survey, children with chronic pain were more likely to use specialty care but not mental health care. The higher likelihood of emergency care use in this group raises the question of whether better management of pediatric chronic pain could reduce emergency department use.
Perspective
Among children with chronic pain, we show high rates of use of emergency care but limited use of mental health care, which may suggest opportunities to increase multidisciplinary treatment of chronic pain. 相似文献980.
Igor I. Ponomarev Olga M. Zhigalina Kirill M. Skupov Alexander D. Modestov Victoria G. Basu Alena E. Sufiyanova Ivan I. Ponomarev Dmitry Y. Razorenov 《RSC advances》2019,9(47):27406
Crystalline platinum nanoparticles supported on carbon nanofibers were synthesized for use as an electrocatalyst for polymer electrolyte membrane fuel cells. The nanofibers were prepared by a method of electrospinning from polymer solution with subsequent pyrolysis. Pt nanoneedles supported on polyacrylonitrile pyrolyzed electrospun nanofibers were synthesized by chemical reduction of H2[PtCl6] in aqueous solution. The synthesized electrocatalysts were investigated using scanning, high resolution transmission and scanning transmission electron microscopies, EDX analysis and electron diffraction. The shape and the size of the electrocatalyst crystal Pt nanoparticles were controled and found to depend on the method of H2[PtCl6] reduction type and on conditions of subsequent thermal treatment. Soft Pt reduction by formic acid followed by 100 °C thermal treatment produced needle-shape Pt nanoparticles with a needle length up to 25 nm and diameter up to 5 nm. Thermal treatment of these nanoparticles at 500 °C resulted in partial sintering of the Pt needles. When formic acid was added after 24 h from the beginning of platinization, Pt reduction resulted in small-size spherical Pt nanoparticle of less than 10 nm in diameter. Reduction of H2[PtCl6], preadsorbed on electrospun nanofibers in formic acid with further treatment in H2 flow at 500 °C, resulted in intensive sintering of platinum particles, with formation of conglomerates of 50 nm in size, however, individual particles still retain a size of less than 10 nm. Electrochemically active surface area (ECSA) of Pt/C catalyst was measured by electrochemical hydrogen adsorption/desorption measurements in 0.5 M H2SO4. ECSA of needle-shape Pt nanoparticles was 25 m2 g−1. It increased up to 31 m2 g−1 after thermal treatment at 500 °C, likely, due to amorphous structures removal from carbon nanofibers and retaining of Pt nanoneedle morphology. ECSA of small-size spherical Pt nanoparticles was 26 m2 g−1. Further thermal treatment at 500 °C in vacuum decreased ECSA down to 20 m2 g−1 due to Pt sintering and Pt active sites deactivation. The thermal treatment of small-size spherical Pt nanoparticles in H2 flow at 500 °C produced agglomerates of Pt nanoparticles with ECSA of 14 m2 g−1.Platinum nanoparticle electrocatalysts on carbon nanofibers are engineered and optimized by varying reduction procedure and thermal treatment temperature and medium. 相似文献