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1.
INVOLVEMENT OF SINGLET OXYGEN IN THE PHOTOTOXICITY MECHANISM FOR A METABOLITE OF PIROXICAM 总被引:1,自引:0,他引:1
A. Western J. R. Van Camp R. Bensasson E. J. Land I. E. Kochevar 《Photochemistry and photobiology》1987,46(4):469-475
It has been previously shown that a metabolite of piroxicam but not piroxicam itself causes phototoxicity to cells in vitro after exposure to UVA (320–400 nm) radiation. The phototoxicity mechanism for this metabolite, 2-methyl-4-oxo-2H-l,2-benzothiazine-l,l-dioxide (Compound I), was investigated. In vitro phototoxicity to human mononuclear cells was assayed using 0.5 m M Compound I and UVA radiation. The UVA fluence required for phototoxicity of Compound I was lower by a factor of 2-3 in D2 O buffer compared to H2 O buffer. Superoxide dismutase and mannitol, which remove O2 - and OH", respectively, do not decrease the phototoxicity. The photodecomposition of Compound I was inhibited by sodium azide, enhanced by human serum albumin and unaffected by mannitol. Stable photoproducts of Compound I were not toxic to the cells. The quantum yield of singlet oxygen based on its emission at 1270 nm was 0.19 and 0.35 for Compound I and s2 ± 10-3 and 10-2 for piroxicam in D2 O and C6 H6 , respectively. While the extremely low quantum yield for singlet oxygen from piroxicam appears to account for its lack of phototoxicity, the phototoxicity mechanism for its metabolite, Compound I, most likely does involve singlet oxygen. 相似文献
2.
Ab initio multireference configuration interaction potential energy surfaces are computed for the eight lowest singlet surfaces of C(3). These reveal several important features, including several conical intersections in linear, nonlinear, and equilateral triangle geometries. These intersections are important because, particularly for the excited A (1)Pi(u) state, reasonable ab initio results could only be obtained by including nearby, near degenerate, (1)Sigma(u) (-) and (1)Delta(u) states that cross the A (1)Pi(u) state around 4500 cm(-1) above the equilibrium geometry, and a (1)Pi(g) state whose potential in turn crosses the other states about 2000 cm(-1) further up. These states are probably responsible for the complexity of the shorter wavelength UV absorption spectrum of C(3). The computed potential energy surface for the ground, X (1)Sigma(g) (+), state and for the lowest two excited singlet surfaces (which both correlate with the A (1)Pi(u) state in a collinear geometry) are fitted to analytic functional forms. Vibrational energy levels are calculated for both states, taking account of the Renner-Teller coupling in the excited A (1)Pi(u) state. The potential parameters for both states are then least-squares fitted to experimental data. The ground-state fit covers a range of approximately 8500 cm(-1) above the lowest level, and reproduces 100 observed vibrational levels with an average error of 2.8 cm(-1). The A (1)Pi(u) state surfaces cover a range of 3250 cm(-1) above the zero-point level, and reproduce the 44 observed levels in this range with an average error of 2.8 cm(-1). 相似文献
3.
Intracellular localization of sulfonated meso-tetraphenylporphines in a human carcinoma cell line 总被引:3,自引:0,他引:3
The intracellular localization of meso-tetraphenylporphines sulfonated to different degrees (TPPSn), in a human cervix carcinoma cell line (NHIK 3025), was studied by fluorescence microscopy and fluorescence spectroscopy. After an 18 h incubation, TPPS4, TPPS2a and TPPS2o were localized in extranuclear granules. Studies of cells stained with both TPPS4, and acridine orange, which is known to fluoresce red in lysosomes, indicated that these granules were lysosomes. In addition, a fraction of the cellbound TPPS4, TPPS2a and TPPS2o seems to be associated with the plasma membrane. Fluorescence quenching studies of cells doublestained with acridine orange and TPPS4 indicated that TPPS4 is also localized in the nucleus and in the extralysosomal cytoplasm. The intracellular location of TPPS1 differed from that of the other TPPSns studied: In 6 out of 9 experiments fluorescing extranuclear granules were found. A diffuse fluorescence extending from the perinuclear area was also observed. 相似文献
4.
Modelling of multi-bodies in close proximity under water waves——Fluid resonance in narrow gaps 总被引:1,自引:0,他引:1
LU Lin TENG Bin CHENG Liang SUN Liang & CHEN XiaoBo Center for Deepwater Engineering Dalian University of Technology Dalian China State Key Laboratory of Structural Analysis for Industrial Equipment State Key Laboratory of Coastal Offshore Engineering School of Civil Resource Engineering The University of Western Australia Crawly Australia Centre for Offshore Research... 《中国科学:物理学 力学 天文学(英文版)》2011,(1)
Viscous fluid model and potential flow model with and without artificial damping force(f=-μV,μ the damping coefficient and V the local averaging flow velocity) are employed in this work to investigate the phenomenon of fluid resonance in narrow gaps between multi-bodies in close proximity under water waves.The numerical results are compared with experimental data available in the literature.The comparison demonstrates that both the viscous fluid model and the potential flow model are able to predict the res... 相似文献
5.
ERYTHROPOIETIC PROTOPORPHYRIA: PHOTODYNAMIC TRANSFER OF PROTOPORPHYRIN FROM INTACT ERYTHROCYTES TO OTHER CELLS 总被引:1,自引:0,他引:1
Atle Brun André Western Zvi Malik Sverre Sandberg 《Photochemistry and photobiology》1990,51(5):573-577
Erythrocytes in patients with erythropoietic protoporphyria (EPP) contain large amounts of protoporphyrin and are regarded as the main source of protoporphyrin in this disease. Cells in the skin of EPP patients accumulate protoporphyrin released from the erythrocytes and upon sun exposure endothelial cells are photodamaged. In the present study a light-induced transfer of protoporphyrin directly from EPP erythrocytes to cultured cells is demonstrated. Erythrocytes were layered upon cultured cells and irradiated. The nearness of erythrocyte and cultured cell membranes potentiated the transfer of protoporphyrin between these cells. This transfer was rapid and preceded the release of protoporphyrin to proteins in the medium. Further irradiation of the protoporphyrin-enriched cultured cells, after removal of the erythrocytes, caused severe photodamage to the cells and survival was dependent on both the amount of protoporphyrin transferred and on the light fluence. Clinical observations and the results of this study indicate that light energy may be involved in two steps in the pathophysiology of EPP: (A) light-induced release of protoporphyrin from erythrocytes to endothelial cells and (B) photodynamic damage to protoporphyrin-enriched endothelial cells. 相似文献
6.
Andersson S Arasa C Yabushita A Yokoyama M Hama T Kawasaki M Western CM Ashfold MN 《Physical chemistry chemical physics : PCCP》2011,13(35):15810-15820
The photodesorption of H(2)O in its vibrational ground state, and of OH radicals in their ground and first excited vibrational states, following 157 nm photoexcitation of amorphous solid water has been studied using molecular dynamics simulations and detected experimentally by resonance-enhanced multiphoton ionization techniques. There is good agreement between the simulated and measured energy distributions. In addition, signals of H(+) and OH(+) were detected in the experiments. These are inferred to originate from vibrationally excited H(2)O molecules that are ejected from the surface by two distinct mechanisms: a direct desorption mechanism and desorption induced by secondary recombination of photoproducts at the ice surface. This is the first reported experimental evidence of photodesorption of vibrationally excited H(2)O molecules from water ice. 相似文献
7.
采用传统方法生产的NbTi/Cu多芯超导线在生产芯数较多的超导线时存在填充系数较大的问题,这直接影响了芯丝的整齐排布,所以组装完成后加入热等静压过程.研究了经过热等静压和未经过热等静压的NbTi/Cu多芯超导线的加工性能.经过试验证明,经过100~150MP,2小时热等静压处理的NbTi/Cu多芯超导线坯锭在加工过程中具有良好的加工性能,提高了超导线复合坯锭的成品率;而未经过热等静压处理的NbTi/Cu多芯超导线坯锭加工性能较差,坯锭内部缺陷较多. 相似文献
8.
Gang Li Jeremy J. Harrison Ram S. Ram Colin M. Western Peter F. Bernath 《Journal of Quantitative Spectroscopy & Radiative Transfer》2012,113(1):67-74
Einstein A coefficients and absolute line intensities have been calculated for the E2Π–X2Σ+ transition of CaH. Using wavefunctions derived from the Rydberg–Klein–Rees (RKR) method and electronic transition dipole moment functions obtained from high-level ab initio calculations, rotationless transition dipole moment matrix elements have been calculated for all 10 bands involving v′=0,1 of the E2Π state and v″=0,1,2,3,4 of the X2Σ state. The rotational line strength factors (Hönl–London factors) are derived for the intermediate coupling case between Hund's case (a) and (b) for the E2Π–X2Σ+ transition. The computed transition dipole moments and the spectroscopic constants from a recent study [Ram et al., Journal of Molecular Spectroscopy 2011;266:86–91] have been combined to generate line lists containing Einstein A coefficients and absolute line intensities for 10 bands of the E2Π–X2Σ+ transition of CaH for J-values up to 50.5. The absolute line intensities have been used to determine a rotational temperature of 778±3 °C for the CaH sample in the recent study. 相似文献
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