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981.
Demidova TN Gad F Zahra T Francis KP Hamblin MR 《Journal of photochemistry and photobiology. B, Biology》2005,81(1):15-25
The increasing occurrence of multi-antibiotic resistant microbes has led to the search for alternative methods of killing pathogens and treating infections. Photodynamic therapy (PDT) uses the combination of non-toxic dyes and harmless visible light to produce reactive oxygen species that can kill mammalian and microbial cells. Although the photodynamic inactivation of bacteria has been known for over a hundred years, its use to treat infections has not been much developed. This may be partly due to the difficulty of monitoring the effectiveness of PDT in animal models of infection. In order to facilitate this monitoring process, we have developed a procedure that uses bioluminescent genetically engineered bacteria and a light sensitive imaging system to allow real-time visualization of infections. When these bacteria are treated with PDT in vitro, the loss of luminescence parallels the loss of colony-forming ability. We have developed several models of infections in wounds and soft-tissue abscesses in mice that can be followed by bioluminescence imaging. The size and intensity of the infection can be sequentially monitored in a non-invasive fashion in individual mice in real-time. When photosensitizers are introduced into the infected tissue followed by illumination with red light, a light-dose dependent loss of luminescence is seen. If the bacterium is invasive, the loss of luminescence correlates with increased survival of the mice, whilst animals in control groups die of sepsis within five days. Healing of the PDT treated wounds is not impaired and may actually be improved. This approach can allow many animal models of localized infections to be accurately monitored for efficacy of treatment by PDT. 相似文献
982.
Alkyl Ether Analogs of Chlorophyll-a Derivatives: Part 1. Synthesis, Photophysical Properties and Photodynamic Efficacy 总被引:2,自引:0,他引:2
Ravindra K. Pandey Adam B. Sumlin Scott Constantine Mohamed Aoudia William R. Potter David A. Bellnier Barbara W. Henderson Michael A. Rodgers Kevin M. Smith Thomas J. Dougherty 《Photochemistry and photobiology》1996,64(1):194-204
The synthesis, preliminary in vivo biological activity, singlet oxygen and fluorescence yields of a series of alkyl ether derivatives of chlorophyll-a analogs are described. For short-chain carbon ethers (1–7carbon units), it was observed that the biological activity increased by increasing the length of the carbon chain, being maximum in compounds with n-hexyl and n-heptyl chains. Related sensitizers prepared by reacting 2-(1-bromoethyl)-2-devinylpyropheophorbide-a with (sec)alcohols were found to be less effective. Under similar treatment conditions, photosensitizers containing cis- and trans- 3-hexenyl side chains were ineffective. Thus, both stereochemical and steric factors caused differences in sensitizing activity. In general, pyropheophorbide-a analogs were found to be more active than related chlorin e6 derivatives, in which the isocyclic ring (ring “E”) was cleaved. Related photosensitizers in the 9-deoxy- series were found to be as effective as the corresponding pyropheophorbide-a analogs. The photosensitizers prepared from pyropheophorbide-a methyl ester and chlorin e6 trimethyl ester have long wavelength absorption at 660 nm (ε 45000 to 50000). Reduction of the carbonyl group in the pyropheophorbide-a to methylene (ring E) resulted in a blue shift to 648 nm (ε 38000). 相似文献
983.
984.
985.
To compare the ligand-based reduction chemistry of (EPh)(-) ligands in a metallocene environment to the sterically induced reduction chemistry of the (C(5)Me(5))(-) ligands in (C(5)Me(5))(3)Sm, (C(5)Me(5))(2)Sm(EPh) (E = S, Se, Te) complexes were synthesized and treated with substrates reduced by (C(5)Me(5))(3)Sm: cyclooctatetraene; azobenzene; phenazine. Reactions of PhEEPh with (C(5)Me(5))(2)Sm(THF)(2) and (C(5)Me(5))(2)Sm produced THF-solvated monometallic complexes, (C(5)Me(5))(2)Sm(EPh)(THF), and their unsolvated dimeric analogues, [(C(5)Me(5))(2)Sm(mu-EPh)](2), respectively. Both sets of the paramagnetic benzene chalcogenolate complexes were definitively identified by X-crystallography and form homologous series. Only the (TePh)(-) complexes show reduction reactivity and only upon heating to 65 degrees C. 相似文献
986.
Novel microemulsion and micellar HPLC separations have been achieved using gradient elution and columns packed with reverse phase material. Initial attempts at gradient microemulsion liquid chromatography proved impossible on use of a microemulsion successfully used in capillary electrophoresis. Optimisation of the microemulsion composition allowed the generation of stable microemulsions to achieve separations in HPLC. The novel use of organic-solvent micellar chromatography in gradient elution mode was shown to give efficient separations. A range of efficient separations of pharmaceuticals and related impurities were obtained. Acidic, basic, and neutral solutes were resolved covering a wide range of water solubilities and polarities. Elution times were in the order of 4-15 minutes. Separations were briefly compared to those accomplished with a micellar HPLC system. It is proposed that gradient elution in both microemulsion and micellar HPLC can be regarded as a highly successful means of achieving resolution of complex mixtures and should be considered for routine analysis and further investigation. 相似文献
987.
The advances in understanding the kinetic behavior of certain environmental electron transfer (ET) systems are presented. Emphasis is placed on the homogeneous ET chemistry of transition metals, particularly the FeII/III system, in various relevant forms. In the context of modern ET theory, we examine the utility of computational chemistry methods for the calculation of ET quantities such as the reorganization energy and electronic coupling matrix element. We discuss successful application of the methods to topics of homogeneous oxidation of dissolved metal ions by molecular oxygen in aqueous solution, as well as the prediction of electron mobility in solid phase iron oxide crystals. The examples illustrate the significant potential for many more advances in understanding environmental ET systems through the combination of ET theory and computational chemistry. 相似文献
988.
The concentration and glycosylation of alpha(1)-acid glycoprotein (AGP) alter significantly during inflammation. A definitive physiological role for AGP remains elusive and is the subject of extensive investigation. This study investigated the influence of AGP on the activity of collagenase-3, an important mediator of cartilage destruction in rheumatoid arthritis. AGP was isolated from normal and rheumatoid plasma. Fucosylation was determined by high pH anion-exchange chromatography; sialylation was assessed following enzymatic digest. Rheumatoid AGP displayed elevated fucosylation and sialylation compared with normal. The influence of each sample on collagenase-3 activity was measured fluorometrically. AGP influenced collagenase-3 catalysis and collagen binding, with catalytic activity correlating with fucosylation. Rheumatoid AGP exhibited less efficient inhibition than normal plasma AGP. It is hypothesized that AGP within rheumatoid synovial fluid may be inadequate to prevent excessive cartilage destruction and hence may exacerbate the disease process. 相似文献
989.
The synthesis and characterization of compounds of the type Hg[1-C(6)H(4)-2-C(H)=NC(6)H(5-n)R(n)](2)
Flower KR Howard VJ Naguthney S Pritchard RG Warren JE McGown AT 《Inorganic chemistry》2002,41(7):1907-1912
The organomercurial compounds Hg[1-C(6)H(4)-2-C(H)=NC(6)H(5-n)R(n)](2) (R = 4-NMe(2), 6a; 4-Me, 6b; 4-I, 6c; 4-NO(2), 6d; 2-(i)Pr, 6e; 2-Me, 6f; 2,6-(i)Pr(2), 6g; 2,6-Me(2), 6h) have been prepared in good overall yield from 2-bromobenzaldehyde. All of the compounds have been characterized by elemental analysis, (1)H NMR, (13)C[(1)H] NMR, and infrared spectroscopy. In addition, compounds 6a [C(30)H(30)HgN(4), triclinic, P, a = 6.20000(10) A, b = 9.2315(2) A, c = 10.9069(3) A, alpha = 85.8510(10) degrees, beta = 89.3570(10) degrees, gamma = 87.206(2) degrees, Z = 1], 6b [C(28)H(24)HgN(2), monoclinic, P2(1)/c, a = 12.8260(5) A, b = 14.0675(4) A, c = 6.1032(2) A, beta = 90.0990(10) degrees, Z = 2], 6g [C(38)H(44)HgN(2), triclinic, P, a = 8.2626(2) A, b = 9.8317(2) A, c = 11.8873(3) A, alpha = 103.6650(10) degrees, beta = 109.3350(10) degrees, gamma = 104.627(2) degrees, Z = 1], and 6h [C(30)H(28)HgN(2), monoclinic, P2(1)/c, a = 12.5307(2) A, b = 10.9852(2) A, c = 18.2112(2) A, beta = 104.0190(10) degrees, gamma = 87.206(2) degrees, Z = 4] have been characterized by low-temperature single-crystal X-ray diffraction studies, and two different molecular geometries about the central mercury atom have been observed; intramolecular contacts suggest a van der Waals radius for Hg of 2.1-2.2 A. 相似文献
990.
Pulacchini S Nasser R Sibbons KF Motevalli M Hawkes GE Kroemer RT Bento ES Watkinson M 《Organic & biomolecular chemistry》2003,1(22):4058-4063
Investigations into the conformational behaviour of macrocyclic ligands 5 and 6 derived from (R,R)-1,2-diaminocyclohexane have been undertaken using molecular modelling, single crystal X-ray diffraction and variable temperature 1H NMR spectroscopy. These have revealed that the lowest energy conformers in both cases do not possess the expected C2-element of symmetry, which can only be accessed at higher temperatures. Instead both molecules exist as C1-conformers at room temperature and in the solid state. In solution a range of dynamic exchange processes is observed which result, in part from the inherent strain in these fused bicyclic systems. An unexpected but characteristic feature of the C1-symmetric conformers is highlighted by the presence of a signal at unexpectedly low field in their 1H NMR spectra due to the interaction of two of the sulfonyl oxygen atoms with one of the bridgehead hydrogen atoms. 相似文献