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排序方式: 共有967条查询结果,搜索用时 31 毫秒
181.
Radosaw Szalak Wirginia Kukula-Koch Magorzata Matysek Marta Kruk-Somka Wojciech Koch Lidia Czernicka Daariimaa Khurelbat Grayna Biaa Marcin B. Arciszewski 《International journal of molecular sciences》2021,22(9)
Neurodegenerative diseases associated with memory disturbances are important health issues occurring due to a prolonged life span. This article presents the results of a study targeting the emergence of a drug candidate with antiamnesic properties. The effect of berberine (BBR), an isoquinoline alkaloid isolated from the overground parts of Berberis sibirica Pall., on memory and expression of parvalbumin in the mouse hippocampus proper were determined. High-purity BBR was isolated by centrifugal partition chromatography from a methanolic extract from B. sibirica by using a methyl-tert-butyl ether and water (1:1 v/v) solvent system with 10 mmol/L of triethylamine and hydrochloric acid. In an in vivo study, we assessed the influence of the chronic administration of BBR on different stages of memory-related responses in mice. Our results indicated that the chronic administration of BBR in a higher dose (5 mg/kg) improves long-term memory acquisition in mice, as determined in the passive avoidance test. The hippocampal CA1–CA3 fields showed an increased number of parvalbumin-immunoreactive neurons (PV-IR) and nerve fibers as compared to the control. No significant changes in the dentate gyrus were observed between the groups. The HPLC-ESI-QTOF-MS/MS analysis of the biological material revealed the content of BBR as 363.4 ± 15.0 ng (4.11% of RSD) per brain, 15.06 ± 0.89 ng (5.91% of RSD) per hippocampus, and 54.45 ± 1.40 (4.05% of RSD) ng in 100 µL plasma. The study showed that BBR could be a factor influencing the expression of PV in hippocampal neurons. We speculate that BBR may modulate the level of Ca2+ in neurons and thus potentially act as a neuroprotective factor against neuronal damages. 相似文献
182.
In a search for new thermoelectric materials, indium oxide (In2O3) was selected as a candidate for high-temperature thermoelectric oxide materials due to its intrinsically low thermal conductivity (<2 W/mK) and ZT values around 0.05. However, low electrical conductivity is a factor limiting the thermoelectric performance of this oxide, and was addressed in this study by Mo doping. It was found that Mo is soluble in In2O3 but forms secondary phases at a fraction near x = 0.06 and higher. Mo was found to be unsuitable for heavy n-type doping necessary to improve the thermoelectric performance of the oxide to the desired level (ZT = 1). However, the experimental data enabled us to analyze the electrical conductivity behavior and the Seebeck coefficient of doped In2O3 with different carrier concentrations, predicting a theoretically achievable maximum power factor value of 1.77 × 10?3 W/mK2 at an optimum carrier concentration. This estimation predicts the highest ZT value of 0.75 at 1073 K, assuming the lattice thermal conductivity value remaining at an amorphous level. 相似文献
183.
Magorzata Prokopowicz Adam Jarmua Yannick Casamayou-Boucau Fiona Gordon Alan Ryder Justyna Sobich Piotr Maj Joanna Ciela Zbigniew Zieliski Piotr Fita Wojciech Rode 《International journal of molecular sciences》2021,22(5)
A homo-dimeric enzyme, thymidylate synthase (TS), has been a long-standing molecular target in chemotherapy. To further elucidate properties and interactions with ligands of wild-type mouse thymidylate synthase (mTS) and its two single mutants, H190A and W103G, spectroscopic and theoretical investigations have been employed. In these mutants, histidine at position 190 and tryptophan at position 103 are substituted with alanine and glycine, respectively. Several emission-based spectroscopy methods used in the paper demonstrate an especially important role for Trp 103 in TS ligands binding. In addition, the Advanced Poisson–Boltzmann Solver (APBS) results show considerable differences in the distribution of electrostatic potential around Trp 103, as compared to distributions observed for all remaining Trp residues in the mTS family of structures. Together, spectroscopic and APBS results reveal a possible interplay between Trp 103 and His190, which contributes to a reduction in enzymatic activity in the case of H190A mutation. Comparison of electrostatic potential for mTS complexes, and their mutants, with the substrate, dUMP, and inhibitors, FdUMP and N-OH-dCMP, suggests its weaker influence on the enzyme–ligand interactions in NOH-dCMP-mTS compared to dUMP-mTS and FdUMP-mTS complexes. This difference may be crucial for the explanation of the ”abortive reaction” inhibitory mechanism of NOH-dCMP towards TS. In addition, based on structural analyses and the H190A mutant capacity to form a denaturation-resistant complex with N-OH-dCMP in the mTHF-dependent reaction, His190 is apparently responsible for a strong preference of the enzyme active center for the anti rotamer of the imino inhibitor form. 相似文献
184.
Wojciech Polkowski Natalia Sobczak Grzegorz Bruzda Artur Kudyba Rafal Nowak Adelajda Polkowska Izabela Krzak Adam Tchrz Donatella Giuranno 《SILICON》2020,12(7):1639-1649
Silicon-boron alloys have been recently pointed out as novel ultra-high temperature phase change materials for applications in Latent Heat Thermal Energy S 相似文献
185.
Karolina Bossak-Ahmad Dr. Tomasz Frączyk Prof. Dr. Wojciech Bal Dr. Simon C. Drew 《Chembiochem : a European journal of chemical biology》2020,21(3):331-334
The apparent affinity of human serum albumin (HSA) for divalent copper has long been the subject of great interest, due to its presumed role as the major Cu2+-binding ligand in blood and cerebrospinal fluid. Using a combination of electronic absorption, circular dichroism and room-temperature electron paramagnetic resonance spectroscopies, together with potentiometric titrations, we competed the tripeptide GGH against HSA to reveal a conditional binding constant of log c =13.02±0.05 at pH 7.4. This rigorously determined value of the Cu2+ affinity has important implications for understanding the extracellular distribution of copper. 相似文献
186.
187.
Mykhailo Chaika Wojciech Paszkowicz Wiesław Strek Dariusz Hreniak Robert Tomala Nadiya Safronova Andriy Doroshenko Sergiy Parkhomenko Piotr Dluzewski Mirosław Kozłowski Oleh Vovk 《Journal of the American Ceramic Society》2019,102(4):2104-2115
In the present work, the influence of Cr and Ca co-additives on the phase formation under conditions emulated the real sintering process of Cr4+:YAG ceramics is studied. The XRD analysis of the treated samples revealed the difference in formation rates of intermediate phases between the samples with and without the Cr2O3 additive. The formation of intermediate phases in the solid-state reaction between Y2O3 and Al2O3 is observed to shift toward higher temperatures (ie, toward the stage of fast shrinkage) if the mixture of Cr2O3 and CaO is added. The reason for such shift is the appearance of new intermediate, which contains Cr4+ ions in perovskite structure, as has been established by optical absorption and luminescent investigations. It is found that the Cr,Ca:YAG ceramics prepared by vacuum solid state reaction sintering at 1750°C, 10 hours possesses better optical transparency than Ca:YAG ceramics prepared under the same conditions. 相似文献
188.
Wojciech Kolasiński 《Materials Research Bulletin》1984,19(7):873-876
The observations of the formation of liquid inclusions in KDP single crystals grown from aqueous solution in static conditions are presented. It was found that the mechanism of creation of inclusions as proposed by Chernov may be applied to understand their morphology. 相似文献
189.
Wojciech Mokrzycki 《Computers & Graphics》1988,12(3-4):477-487
In this paper new methods of discretization (integer approximation) of algebraic spatial curves in the form of intersecting surfaces P(x, y, z) = 0 and Q(x, y, z) = 0 are analyzed.
The use of homogeneous cubical grids G(h3) to discretize a curve is the essence of the method. Two new algorithms of discretization (on 6-connected grid G6c(h3) and 26-connected grid G26(h3)) are presented based on the method above. Implementation of the algorithms for algebraic spatial curves is suggested. The elaborated algorithms are adjusted for application in computer graphics and numerical control of machine tools. 相似文献
190.
This paper describes an experimental implementation of the Edison programming language for a network of microcomputers based on the Z-80 microprocessor. The resulting Edison-N system allows parallel execution of concurrent processes. Its aim is to assist in teaching the principles of concurrent programming. 相似文献