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61.
Olga Taussky Alfred P. Sloan 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1979,30(2):370-373
Matrices and operators of the formA
–1
A
* have received a certain amount of attention in recent years. Here some of the literature is surveyed and the caseA
–1
A is studied for complex matrices withA denoting the transpose ofA. A generalization ofA
–1
A is introduced.
Dedicated to Eduard Stiefel by a long time admirer 相似文献
Zusammenfassung Matrizen und Operatoren, die in der FormA –1 A * ausgedrückt werden können, sind in den letzten Jahren häufig studiert worden. Hier wird ein Ueberblick über Teil der relevanten Literatur gegeben und auch der FallA –1 A für komplexe Matrizen studiert, wobeiA die Transponierte vonA ist. Es wird auch eine Verallgemeinerung vonA –1 A eingeführt.
Dedicated to Eduard Stiefel by a long time admirer 相似文献
62.
Olga V. Zhukova Evgenia V. Arkhipova Tatiana F. Kovaleva Daria A. Zykova Natalya A. Dubovskaya 《Molecules (Basel, Switzerland)》2022,27(14)
Cancer is a leading cause of mortality globally. Despite remarkable improvements in cancer-treatment approaches, disease recurrence and progression remain major obstacles to therapy. While chemotherapy is still a first-line treatment for a variety of cancers, the focus has shifted to the development and application of new approaches to therapy. Nevertheless, the relationship between immune response, neoplastic diseases and treatment efficiency is not fully understood. Therefore, the aim of the study was to investigate the immunopharmacological effects of methacrylic acid homopolymer in an in vivo tumor model. Materials and methods: Monomeric methacrylic acid was used to synthesize polymers. Methacrylic acid was polymerized in dioxane in the presence of 4-Cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid. To study the molecular weight characteristics of PMAA by GPC, carboxyl groups were preliminarily methylated with diazomethane. An experimental cancer model was obtained by grafting RMK1 breast cancer cells. The serum levels of IL-6, IL-10, IL-17, transforming growth factor β1 (TGF-β1), and tumor necrosis factor α (TNF-α) were measured by ELISA. Results: The effect of PMAA on the serum concentrations of several cytokines was studied upon its single administration to laboratory animals in early neoplastic process. The IL-6, IL-17 and TGF-β1 concentrations were found to change significantly and reach the level observed in intact rats. The IL-10 concentration tended to normalize. Conclusion: The positive results obtained are the basis for further studies on the effect of methacrylic-acid polymers with different molecular-weight characteristics on the neoplastic process. 相似文献
63.
Olga Bakulina Anton Bannykh Ekaterina Levashova Mikhail Krasavin 《Molecules (Basel, Switzerland)》2022,27(12)
Screening of a library of novel N-hydroxylactams amenable by the Castagnoli-Cushman reaction identified four lead compounds that facilitated 55Fe transport into P. aeruginosa cells (one of these synthetic siderophores was found to be as efficient at promoting iron uptake as the natural siderophores pyoverdine, pyochelin or enterobactin). Conjugates of the four lead siderophores with ciprofloxacin were tested for antibacterial activity against P. aeruginosa POA1 (wild type) and the ∆pvdF∆pchA mutant strain. The antibacterial activity was found to be pronounced against the ∆pvdF∆pchA mutant strain grown in CAA medium but not for the POA1 strain. This may be indicative of these compounds being ‘Trojan horse’ antibiotics. Further scrutiny of the mechanism of the antibacterial action of the newly developed conjugates is warranted. 相似文献
64.
Lyubov G. Dezhenkova Anna A. Druzina Yulia L. Volodina Nadezhda V. Dudarova Natalia A. Nekrasova Olga B. Zhidkova Mikhail A. Grin Vladimir I. Bregadze 《Molecules (Basel, Switzerland)》2022,27(14)
A series of novel cobalt bis(dicarbollide)—curcumin conjugates were synthesized. Two conjugates were obtained through the nucleophilic ring-opening reaction of the 1,4-dioxane and tetrahydropyran derivatives of cobalt bis(dicarbollide) with the OH group of curcumin, and using two equiv. of the oxonium derivatives, two other conjugates containing two cobalt bis(dicarbollide) units per molecule were obtained. In contrast to curcumin, the conjugates obtained were found to be non-cytotoxic against both tumor and normal cell lines. The analysis of the intracellular accumulation of the conjugates by flow cytometry showed that all cobalt bis(dicarbollide)—curcumin conjugates entered HCT116 colorectal carcinoma cells in a time-dependent manner. New non-cytotoxic conjugates contain a large amount of boron atoms in the biomolecule and can potentially be used for further biological research into boron neutron capture therapy (BNCT). 相似文献
65.
Yaron Haviv Olga Georgiev Tal Gaver-Bracha Sharleen Hamad Alina Nemirovski Rivka Hadar Yair Sharav Doron J. Aframian Yariv Brotman Joseph Tam 《Molecules (Basel, Switzerland)》2022,27(14)
Background: the endocannabinoid system (ECS) participates in many physiological and pathological processes including pain generation, modulation, and sensation. Its involvement in chronic orofacial pain (OFP) in general, and the reflection of its involvement in OFP in salivary endocannabinoid (eCBs) levels in particular, has not been examined. Objectives: to evaluate the association between salivary (eCBs) levels and chronic OFP. Methods: salivary levels of 2 eCBs, anandamide (AEA), 2-arachidonoylglycerol (2-AG), 2 endocannabinoid-like compoundsN-palmitoylethanolamine (PEA), N-oleoylethanolamine (OEA), and their endogenous precursor and breakdown product, arachidonic acid (AA), were analyzed using liquid chromatography/tandem mass spectrometry in 83 chronic OFP patients and 43 pain-free controls. The chronic OFP patients were divided according to diagnosis into musculoskeletal, neurovascular/migraine, and neuropathic pain types. Results: chronic OFP patients had lower levels of OEA (p = 0.02) and 2-AG (p = 0.01). Analyzing specific pain types revealed lower levels of AEA and OEA in the neurovascular group (p = 0.04, 0.02, respectively), and 2-AG in the neuropathic group compared to controls (p = 0.05). No significant differences were found between the musculoskeletal pain group and controls. Higher pain intensity was accompanied by lower levels of AA (p = 0.028), in neuropathic group. Conclusions: lower levels of eCBs were found in the saliva of chronic OFP patients compared to controls, specifically those with neurovascular/migraine, and neuropathic pain. The detection of changes in salivary endocannabinoids levels related to OFP adds a new dimension to our understanding of OFP mechanisms, and may have diagnostic as well as therapeutic implications for pain. 相似文献
66.
The absolute configuration of the title acid 2 has been determined to be S by X-ray crystallography. Thus, decarboxylation of 2 produces (S)-(+)-halothane with 99% retention of configuration. This behavior is compared to other stereoselective decarboxylation reactions of α-haloacids from the literature that also gave high degrees of retention of configuration when in the form of their quaternary ammonium salts, which contain one proton. The proton of the ammonium salt is necessary in order to protonate the anionic intermediate formed from decarboxylation. In the absence of this relatively acidic proton, we had previously found that using triethylene glycol (TEG) as both the solvent and proton source for the decarboxylation reaction of acid 2 caused poor stereoselectivity. This was in contrast to 1,2,2,2-tetrafluoro-1-methoxypropionic acid 6, which showed a high degree of retention of configuration in TEG. In order to rationalize this differing behavior, we report DFT studies at PCM-B3LYP/6-31++G7 level of theory (the results were additionally confirmed with 6-311++G7 and aug-cc-pVDZ basis sets). The energy barrier to inversion of configuration of the anionic reaction intermediate 11 of acid 2 is 10.23 kcal/mol. However, we find that the anionic intermediate 10 from acid 6 would rather undergo β-elimination instead of inversion of configuration. Thus the planar transition state required for inversion of configuration is never reached, regardless of the rate of proton transfer to the anion. 相似文献
67.
68.
Dr. Jaroslav Malina Dr. Olga Novakova Prof. Dr. Giovanni Natile Prof. Dr. Viktor Brabec 《化学:亚洲杂志》2012,7(5):1026-1031
The PtII-coordination complex [PtCl2(DAB)] (DAB=2,3-diaminobutane) belongs to a class of cytotoxic cisplatin analogues that contain chiral diamine ligands. Enantiomeric pairs of these compounds have attracted particular interest because they have different effects on different DNA conformations, which, in turn, influences the binding of damaged-DNA-processing enzymes that control downstream effects of the adducts, and thus exhibit different biological activities of the enantiomers. Herein, we studied the translesion synthesis across the major 1,2-d(GG) intrastrand cross-link formed by the R,R and S,S enantiomers of [Pt(DAB)]2+ in the TGGT sequence by using the enzyme that catalyzes the polymerization of deoxyribonucleotides into a DNA strand. We also employed differential scanning calorimetry (DSC) to measure the thermodynamic changes associated with replication-bypass past 1,2-d(GG) adducts of the [Pt(DAB)]2+ enantiomers. In the sequence TGGT, the 1,2-d(GG) intrastrand cross-links that were formed by the enantiomeric pairs of [Pt(DAB)]2+ inhibited DNA polymerization in a chirality-dependent manner. The thermodynamic data helped to understand the effect of the alterations in thermodynamic stability of DNA caused by the Pt-d(GG) adducts upon DNA polymerization across these lesions. Moreover, these data can possibly explain the influence of these alterations on the ability of many DNA polymerases to bypass adducts of antitumor platinum drugs. These results also highlighted the usefulness of DSC in evaluating the impact of DNA adducts of platinum-coordinated compounds on the processing of these lesions by damaged-DNA processing-enzymes. 相似文献
69.
70.
Edyta M. Greer Christopher V. Cosgriff Olga Lavinda 《Journal of Physical Organic Chemistry》2012,25(12):1293-1298
Pentamethylene chain conformational effects for the Bergman cyclization of the 11‐membered ring enediyne, (3Z)‐3‐cycloundecene‐1,5‐diyne, 2, are examined theoretically with unrestricted Becke, three‐parameter, Lee–Yang–Parr/6‐31 G(d,p) calculations. A C1 symmetric enediyne conformation was found to be the global minimum, where its nonsymmetric pentamethylene chain prevented π‐orbital alignment of the acetylene groups for C–C σ bond product formation. The Bergman cyclization of 2 was found to be conformationally dependent. In a Curtin–Hammett type process, the C1 symmetric 2 inverts to one of the CS or C2 symmetric conformers required for the Bergman cyclization, which produced a CS or C2 symmetric 1,4‐diradical intermediate. The activation energy for the cyclization is slightly higher to reach the C2 symmetry diradical compared with the CS symmetry diradical. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献