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S K Hekmatyar R M Kerkhoff S K Pakin P Hopewell N Bansal 《International journal of hyperthermia》2005,21(6):561-574
MR thermometry techniques based on the strong water 1H signal provide high spatial and temporal resolution and have shown promise for applications such as laser surgery and RF ablation. However, these techniques have low temperature sensitivity for hyperthermia applications and are greatly influenced by local motion and susceptibility variations. 1H NMR signals from paramagnetic lanthanide complexes of Pr3+, Yb3+ and Tm3+ show up to 300-fold stronger temperature dependence compared to the water 1H signal. In addition, 1H chemical shifts of many of these complexes are insensitive to other factors such as the concentration of the paramagnetic complex, pH, [Ca2+], and the presence of plasma macro-molecules and ions. Applications of lanthanide complexes for temperature measurement in intact animals and the feasibility of mapping temperatures in phantoms have been demonstrated. Among all the lanthanide complexes examined so far, thulium 1, 4, 7, 10-tetramethyl-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetate (TmDOTMA-) appears to be the most attractive for in vivo MR thermometry. The 1H signal from the methyl groups on this complex is relatively intense because of 12 equivalent protons and provides high temperature sensitivity because of the large paramagnetic shifts induced by thulium. The possibility of imaging TmDOTMA2--in intact animals at physiologically safe concentrations has recently been demonstrated. Overall, MR thermometry methods based on hyperfine-shifted MR signals from paramagnetic lanthanide complexes appear promising for animal applications, but further studies relating to acceptable dose and signal-to-noise ratio are necessary before clinical use. 相似文献
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Our data suggest that DOX resistance in P388/R-84 cells may result, at least in part, from reduced free radical formation by both suppression of flavin reductase(s) and overexpression of certain antioxidant enzymes such as GSH peroxidase and catalase. In addition, our results, in conjunction with other studies, indicate that flavin reductase(s) and antioxidant enzymes are differentially altered in cancer cells with acquired or de novo resistance to DOX. Further studies are needed, however, to elucidate the mechanism(s) by which the gene expression of these enzymes is regulated in drug-sensitive and -resistant cells. 相似文献
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Garima Chawla Piyush Gupta R Thilagavathi Asit K Chakraborti Arvind K Bansal 《European journal of pharmaceutical sciences》2003,20(3):305-317
This study deals with the generation and characterization of various solid-state forms of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor. The drug was subjected to polymorphic screen using different solvents to explore the possibility of existence of different solid forms. N,N-Dimethyl acetamide (DMA) and N,N-dimethyl formamide (DMF) yielded solvates in 1:1 stoichiometric ratio. Quench cooling of the melt resulted in amorphous form of the drug. All these solid-state forms were characterized by thermoanalytical (DSC, TGA, HSM), crystallographic (XRD), microscopic (polarized, SEM), spectroscopic (FTIR), and elemental analysis techniques. Solubility and van't Hoff studies were carried out for their thermodynamic interpretation. Influence of morphology of different solid-state forms on flow behavior was also investigated. Molecular modeling studies were used to elucidate the interaction between solute and solvent molecules in the solvate. 相似文献
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Himu P. Shukla Ralph P. Mason Navin Bansal Peter P. Antich 《Magnetic resonance in medicine》1996,35(6):827-833
A novel noninvasive method of measuring local myocardial oxygen tension (pO2) In the perfused rat heart using 19F MRI is demonstrated. Tissue pO2 was determined on the basis of the 19F spin-lattice relaxation rate (R1) of perflubron (perfluorooctyl bromide) sequestered in the heart after IV infusion of an emulsion. Spectroscopic measurement of R1 was previously used to measure a global weighted average of oxygen status. 19F MRI now provides 3D spatial resolution indicating local cardiac pO2 under normally perfused, globally ischemic, and regionally ischemic conditions. 相似文献
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Anjali Ramaswamy Nina N. Brodsky Tomokazu S. Sumida Michela Comi Hiromitsu Asashima Kenneth B. Hoehn Ningshan Li Yunqing Liu Aagam Shah Neal G. Ravindra Jason Bishai Alamzeb Khan William Lau Brian Sellers Neha Bansal Pamela Guerrerio Avraham Unterman Victoria Habet Carrie L. Lucas 《Immunity》2021,54(5):1083-1095.e7
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