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991.
Linares R Pacheco JR Good TA 《Journal of photochemistry and photobiology. B, Biology》2004,77(1-3):17-26
The multichain interleukin-2 receptor (IL-2R) has been proposed as a target for immunotherapy in the treatment of certain cancers including adult T-cell leukemia and cutaneous T-cell lymphoma as well as certain autoimmune diseases. The IL-2R is abnormally expressed on cells associated with each of these diseases; while normal, non-activated T-cells do not express the receptor. This report describes the selective photolysis of activated and non-activated IL-2R expressing cells using several immunoconjugates synthesized with one of two photosensitizers, hematoporphyrin (HP) or chlorin-e(6) (Ce(6)), covalently linked to IL-2 or an anti-IL-2R antibody. Destruction of IL-2R bearing cells was achieved after photosensitizer internalization and irradiation using all tested photosensitizer conjugates. Chlorin containing conjugates were more effective, by a factor of 4 or more, than HP containing conjugates. Conjugates made with IL-2 were up to 30 times more effective than conjugates that used a monoclonal antibody against the IL-2R for targeting. Activation of the cells to increase IL-2R expression decreased the internalization time required for optimal therapeutic efficacy; however, stimulation of the cell to increase IL-2 secretion greatly reduced conjugate effectiveness. This work could lead to the development of more effective strategies to treat T-cell diseases. 相似文献
992.
Logan JL Masse P Dorvel B Skolnik AM Sheiko SS Francis R Taton D Gnanou Y Duran RS 《Langmuir : the ACS journal of surfaces and colloids》2005,21(8):3424-3431
A series of three-arm star block copolymers were examined using atomic force microscopy (AFM). These stars consisted of a polystyrene core composed of ca. 111 styrene units/branch with poly(ethylene oxide) (PEO) chains at the star periphery. Each star contained different amounts of PEO, varying from 107 to 415 ethylene oxide units/branch. The stars were spread as thin films at the air/water interface on a Langmuir trough and transferred onto mica at various surface pressures. Circular domains representing 2D micelle-like aggregated molecules were observed at low pressures. Upon further compression, these domains underwent additional aggregation in a systematic manner, including micellar chaining. At this point, domain area and the number of molecules/domain increased with increasing pressure. In addition, it was found that longer PEO chains led to greater intermolecular separation and less aggregation. These AFM results correspond to attributes seen in the surface pressure-area isotherms of the stars. In addition, they demonstrate the viability of AFM as a quantitative characterization technique. 相似文献
993.
Jennifer L. Gottfried Frank C. De Lucia Jr. Chase A. Munson Andrzej W. Miziolek 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007,62(12):1405-1411
We have developed a double-pulse standoff laser-induced breakdown spectroscopy (ST-LIBS) system capable of detecting a variety of hazardous materials at tens of meters. The use of a double-pulse laser improves the sensitivity and selectivity of ST-LIBS, especially for the detection of energetic materials. In addition to various metallic and plastic materials, the system has been used to detect bulk explosives RDX and Composition-B, explosive residues, biological species such as the anthrax surrogate Bacillus subtilis, and chemical warfare simulants at 20 m. We have also demonstrated the discrimination of explosive residues from various interferents on an aluminum substrate. 相似文献
994.
995.
Zachary R. Jones Maksim Y. Livshits Frankie D. White Elodie Dalodire Maryline G. Ferrier Laura M. Lilley Karah E. Knope Stosh A. Kozimor Veronika Mocko Brian L. Scott Benjamin W. Stein Jennifer N. Wacker David H. Woen 《Chemical science》2021,12(15):5638
The positive impact of having access to well-defined starting materials for applied actinide technologies – and for technologies based on other elements – cannot be overstated. Of numerous relevant 5f-element starting materials, those in complexing aqueous media find widespread use. Consider acetic acid/acetate buffered solutions as an example. These solutions provide entry into diverse technologies, from small-scale production of actinide metal to preparing radiolabeled chelates for medical applications. However, like so many aqueous solutions that contain actinides and complexing agents, 5f-element speciation in acetic acid/acetate cocktails is poorly defined. Herein, we address this problem and characterize Ac3+ and Cm3+ speciation as a function of increasing acetic acid/acetate concentrations (0.1 to 15 M, pH = 5.5). Results obtained via X-ray absorption and optical spectroscopy show the aquo ion dominated in dilute acetic acid/acetate solutions (0.1 M). Increasing acetic acid/acetate concentrations to 15 M increased complexation and revealed divergent reactivity between early and late actinides. A neutral Ac(H2O)6(1)(O2CMe)3(1) compound was the major species in solution for the large Ac3+. In contrast, smaller Cm3+ preferred forming an anion. There were approximately four bound O2CMe1− ligands and one to two inner sphere H2O ligands. The conclusion that increasing acetic acid/acetate concentrations increased acetate complexation was corroborated by characterizing (NH4)2M(O2CMe)5 (M = Eu3+, Am3+ and Cm3+) using single crystal X-ray diffraction and optical spectroscopy (absorption, emission, excitation, and excited state lifetime measurements).Actinide complexation from aqueous acetic acid/acetate buffered solutions is described. The number of water ligands was directly correlated with the acetate concentration and characterized by X-ray absorption and optical spectroscopy. 相似文献
996.
Patricia G Yancey Stacia Miles Jennifer Schwegel W Gray Jerome 《Microscopy and microanalysis》2002,8(2):81-93
Foam cells in the atherosclerotic lesion have substantial cholesterol stores within large, swollen lysosomes. This feature is mimicked by incubating THP-1 macrophages with mildly oxidized low density lipoprotein (LDL). Incubation of THP-1 cells with acetylated LDL produces cytoplasmic cholesteryl ester accumulation rather than lysosomal storage. The differences could be due to differences in uptake and delivery of lipoprotein to lysosomes or to lysosomal and post-lysosomal processing events. We compared uptake and lysosomal trafficking of acetylated and oxidized LDL using colloidal gold-labeled lipoproteins. Labeling did not alter cellular cholesterol accumulation. We found that uptake and delivery to lysosomes are not different for acetylated and oxidized LDL. In fact, both oxidized and acetylated LDL can be delivered to the same lysosomes. Sequential incubation with oxidized LDL followed by acetylated LDL showed that the lipid-engorged lysosomes are long-lived structures, continuously accepting newly ingested lipoprotein. Comparison of acetylated and oxidized LDL in mouse peritoneal macrophages, a cell which does not accumulate substantial lysosomal lipid, also revealed no differences in uptake. This indicates that in THP-1 cells, the differences in metabolism of oxidized and acetylated LDL are due to cell-specific lysosomal or post-lysosomal events not present in B6C3F1 mouse macrophages. 相似文献
997.
R.David Crouch Candice A. Romany Anna C. Kreshock Karina A. Menconi Jennifer L. Zile 《Tetrahedron letters》2004,45(6):1279-1281
TES- and TBS-protected alcohols undergo deprotection in good to excellent yield upon heating with 1 equiv of BiOClO4-xH2O in CH2Cl2. TBDPS- and TIPS-protected 2° alcohols are more resistant to deprotection. The use of this method in selective desilylation is, however, limited to the deprotection of alkyl silyl ethers in the presence of TBDPS-protected phenols. 相似文献
998.
Kato N Prime J Katagiri K Caruso F 《Langmuir : the ACS journal of surfaces and colloids》2004,20(14):5718-5723
We report the preparation of aqueous liposome dispersions of J-aggregates formed by the amphiphilic merocyanine dye (MD). A series of liposome-forming lipids were dispersed together with MD J-aggregates at different molar ratios of MD to lipid. The MD J-aggregate dispersions prepared with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) at the MD to DMPC ratio of 0.16 exhibit good dispersibility; that is, they can be readily redispersed without any flocculation even after their precipitation. By use of different counterions for the MD molecules, two types of J-aggregate dispersions, one that exhibits an absorption band (J-band) at 635 nm (type I) and the other at 600 nm (type II), were obtained. As an example of the use of MD J-aggregates liposome dispersions, the thermochromic transformation of MD J-aggregates was demonstrated. When the dispersions are heated, J-aggregates of type I transformed into type II at a certain temperature (T(disp)). The parameters that control the speed of the transformation and the value of T(disp) were determined. 相似文献
999.
Flamigni L Talarico AM Serroni S Puntoriero F Gunter MJ Johnston MR Jeynes TP 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(11):2649-2659
[2]Catenanes made up of several polyether-strapped porphyrin macrocycles interlinked with the cyclic electron acceptor cyclobis(paraquat-p-phenylene) were spectroscopically, photophysically, and electrochemically characterized. The catenanes exhibit very rich redox behavior due to the presence of several different and interacting electro-active subunits. The redox patterns represent useful "fingerprints" that provide detailed information on the electronic interactions and the chemical environments that the electroactive subunits experience in the supramolecular arrays. A photoinduced electron transfer from the porphyrin excited state (charge separation CS) occurs with tau=20 ps in the catenanes with a larger strap and faster than 20 ps (instrumental resolution) in the catenanes with a shorter strap. The resulting charge-separated state recombines to the ground state (charge recombination CR) with lifetimes similar in all cases, 41+/-4 ps. Comparison of the electron transfer rates CS and CR in the host-guest complexes of the same porphyrins with the noncyclic electron acceptor paraquat, indicate slower reactions in the [2]catenanes. This behavior is assigned to the different separation between reacting partners determined by the type of bond (weak interaction or mechanical) and to a two-step consecutive electron transfer to different sites of the macrocyclic electron acceptor in the catenanes which retards charge recombination. 相似文献
1000.
G. Rezaei Behbehani Marie Dillon Jennifer Smyth W. Earle Waghorne 《Journal of solution chemistry》2002,31(10):811-822
The infrared spectra of tetramethylurea have been measured in mixtures of dimethylsulfoxide or acetonitrile with D2O or deuterated methanol (CH3OD). Marked solvatochroism is observed for bands associated with the C=O and C–N stretches of tetramethylurea, with the former moving to lower wavenumber, and the latter to higher, as the concentration of the protic component is increased. The C=O band shows four distinct absorbances, which are attributed to non-, mono, di-, and trihydrogen bonded tetramethylurea. The relative populations of the different hydrogen bonded species were determined from analyses of the C=O band shapes. It is found that the variations in the populations of the different hydrogen bonded species can be accounted for by a simple mass action treatment. 相似文献