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11.
Free radicals induced by adriamycin-sensitive and adriamycin-resistant cells: a spin-trapping study 总被引:1,自引:0,他引:1
The radicals generated by adriamycin-sensitive (CHO-AB) and adriamycin-resistant (CHO-C5) Chinese hamster ovary cells as well as by adriamycin-sensitive and -resistant human breast cancer cells (MCF7-WT and MCF7-ADR) have been studied with spin-trapping and ESR spectroscopy. During anoxic exposure to adriamycin (ADR) both pairs of cell lines produced the broad ESR singlet characteristic of ADR semiquinone (AQ.). By use of tris(oxalato)chromate (CrOx) as an extracellular line-broadening agent, the distribution of AQ. between the intra- and extracellular compartments was studied. For cell densities of (1-3) X 10(7) cells/mL, CrOx eliminated most, though not all, of the ESR signal, indicating that the AQ. radicals freely diffuse and partition between the intra- and extracellular compartments proportionally to their respective volumes. Similar behavior was exhibited by all four cell lines studied. Upon introduction of oxygen to anoxic cells in the presence of the spin trap 5,5-dimethylpyrroline N-oxide (DMPO), the AQ. signal was replaced by that of the DMPO-OH spin adduct. Metal chelators such as desferrioxamine had no effect on DMPO-OH or AQ. formation. Superoxide dismutase, not catalase, totally eliminated the ESR signal, indicating that DMPO-OH produced by ADR-treated cells originates from superoxide rather than from .OH produced from H2O2. In the presence of CrOx, the DMPO-OH signal was not distinguishable from the background noise, thus excluding any contribution to the signal by intracellular spin adducts.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
12.
13.
Current information on the structure and function of motile tubular vacuoles in Pisolithus tinctorius and other fungi is reviewed. The use of fluorochromes to label the vacuole lumen is evaluated and observations on the structure and motility of vacuoles in P. tinctorius are differentiated from possible artifacts. The styryl dyes FM4-64 and MDY-64, used in yeast to demonstrate endocytosis, show little or no labeling of internal membranes in undamaged P. tinctorius cells. This agrees with our data showing that other probes for endocytosis such as Lucifer yellow CH are not taken up by hyphal tip cells. Overall, the observations do not support endocytosis in hyphal tips. It has been suggested that tubular vacuole systems carry out longitudinal transport, and evidence in favor of this hypothesis is evaluated. New data are presented to show that many of the large vacuoles in subapical cells are attached to the plasma membrane and are relatively immobile, while video sequences show movement of fluorochrome in pulses along a series of several large vacuoles, all interconnected via tubules. Tubular vacuoles from thick sections of hyphae processed under anhydrous conditions are shown by X-ray microanalysis to contain relatively high levels of P and K, as seen previously in the larger vacuoles. These results provide further evidence for a role of the tubular vacuoles in longitudinal transport of P. Copyright 1998 Academic Press. 相似文献
14.
Pig to human xenotransplantation is considered a possible solution to the
prevailing chronic lack of human donor organs for allotransplantation. The
Galalpha1,3Gal determinant is the major porcine xenogeneic epitope causing
hyperacute rejection following human antibody binding and complement
activation. In order to characterize the tissue distribution of
Galalpha1,3Gal-containing and blood group- type glycosphingolipids in pig,
acid and nonacid glycosphingolipids were isolated from the kidney, small
intestine, spleen, salivary gland, liver, and heart of a single pig
obtained from a semi-inbred strain homozygous at the SLA locus. Glycolipids
were analyzed by thin-layer immunostaining using monoclonal antibodies, and
following ceramide glycanase cleavage as permethylated oligosaccharides by
gas chromatography, gas chromatography-mass spectrometry, and matrix-
assisted laser desorption/ionization mass spectrometry. The kidney
contained large amounts of Galalpha1,3Gal-containing penta- and
hexasaccharides having carbohydrate sequences consistent with the
Galalpha1,3nLc4and Galalpha1,3Lexstructures, respectively. The former
structure was tentatively identified in all organs by GC/MS. The presence
of extended Galalpha1,3Gal-terminated structures in the kidney and heart
was suggested by antibody binding, and GC/MS indicated the presence of a
Galalpha1,3nLc6structure in the heart. The kidney, spleen, and heart
contained blood group H pentaglycosylceramides based on type 1 (H-5-1) and
type 2 (H-5-2) chains, and H hexaglycosylceramides based on the type 4
chain (H-6-4). In the intestine H-5-1 and H-6-4 were expressed, in the
salivary gland H-5-1 and H-5-2, whereas only the H-5-1 structure was
identified in the liver. Blood group A structures were identified in the
salivary gland and the heart by antibody binding and GC/MS, indicating an
organ- specific expression of blood group AH antigens in the pig.
相似文献
15.
16.
The quinones 1,4-naphthoquinone (NQ), methyl-1,4-naphthoquinone (MNQ), trimethyl-1,4-benzoquinone (TMQ) and 2,3-dimethoxy-5-methyl-1,4-benzoquinone (UQ-0) enhance the rate of nitric oxide (NO) reduction by ascorbate in nitrogen-saturated phosphate buffer (pH 7.4). The observed rate constants for this reaction were determined to be 16±2,215±6,290±14 and 462±18 M-1 s-1, for MNQ, TMQ, NQ and UQ-0, respectively. These rate constants increase with an increase in quinone one-electron redox potential at neutral pH, E71. Since NO production is enhanced under hypoxia and under certain pathological conditions, the observations obtained in this work are very relevant to such conditions. 相似文献
17.
18.
The quinones 1,4-naphthoquinone (NQ), methyl-1,4-naphthoquinone (MNQ), trimethyl-1,4-benzoquinone (TMQ) and 2,3-dimethoxy-5-methyl-1,4-benzoquinone (UQ-0) enhance the rate of nitric oxide (NO) reduction by ascorbate in nitrogen-saturated phosphate buffer (pH 7.4). The observed rate constants for this reaction were determined to be 16±2,215±6,290±14 and 462±18?M-1?s-1, for MNQ, TMQ, NQ and UQ-0, respectively. These rate constants increase with an increase in quinone one-electron redox potential at neutral pH, E71. Since NO production is enhanced under hypoxia and under certain pathological conditions, the observations obtained in this work are very relevant to such conditions. 相似文献
19.
Background
Lyme disease, caused by Borrelia burgdorferi, affects a large number of people in both the USA and Europe. The mouse is a natural host for this spirochete and is widely used as a model system to study Lyme pathogenesis mechanisms. Since disease manifestations often depend upon the spirochete burden in a particular tissue, it is critical to accurately measure the bacterial number in infected tissues. The current methods either lack sensitivity and specificity (SYBR Green), or require independent analysis of samples in parallel to quantitate host and bacterial DNA (TaqMan). We have developed a novel molecular beacon-based convenient multiplex real-time quantitative PCR assay to identify and detect small numbers of B. burgdorferi in infected mouse tissues. 相似文献20.
Thiols oxidation and covalent binding of BSA by cyclolignanic quinones are enhanced by the magnesium cation 总被引:1,自引:0,他引:1
Alegria AE Sanchez-Cruz P Kumar A Garcia C Gonzalez FA Orellano A Zayas B Gordaliza M 《Free radical research》2008,42(1):70-81
A novel cyclolignanic quinone, 7-acetyl-3',4'-didemethoxy-3',4'-dioxopodophyllotoxin (CLQ), inhibits topoisomerase II (TOPO II) activity. The extent of this inhibition was greater than that produced by the etoposide quinone (EQ) or etoposide. Glutathione (GSH) reduces EQ and CLQ to their corresponding semiquinones under anaerobic conditions. The latter were detected by EPR spectroscopy in the presence of MgCl2 but not in its absence. Semiquinone EPR spectra change with quinone/GSH mol ratio, suggesting covalent binding of GSH to the quinones. Quinone-GSH covalent adducts were isolated and identified by ESI-MS. These orthoquinones also react with nucleophilic groups from BSA to bind covalently under anaerobic conditions. BSA thiol consumption and covalent binding by these quinones are enhanced by MgCl2. Complex formation between the parent quinones and Mg+2 was also observed. Density functional calculations predict the observed blue-shifts in the absorption spectra peaks and large decreases in the partial negative charge of electrophilic carbons at the quinone ring when the quinones are complexed to Mg+2. These observations suggest a possible role of Mg+2 chelation by these quinones in increasing TOPO II thiol and/or amino/imino reactivity with these orthoquinones. 相似文献