排序方式: 共有11条查询结果,搜索用时 31 毫秒
1.
A sequential injection analysis procedure with dual-reagent chemiluminescence detection was applied to the screening of street drug seizure samples for the presence of heroin. The chemiluminescence reagents (acidic potassium permanganate and tris(2,2'-bipyridine)ruthenium(III)) were aspirated from either side of a sample aliquot that was sufficiently large to prevent interdispersion of the reagent zones, and therefore two different chemical reactions could be performed simultaneously at either end of the sample zone. The presence of heroin in seizure samples was indicated by a strong response with the tris(2,2'-bipyridine)ruthenium(III) reagent and confirmed by a significant increase in the response with the permanganate reagent when the sample was treated with sodium hydroxide to hydrolyse the heroin to morphine. Nicomorphine (a morphine-derived pharmaceutical) was synthesised and tested under the same conditions. The responses with the permanganate reagent were similar to those for heroin, which supports the proposed chemical basis for the test. However, the responses with tris(2,2'-bipyridine)ruthenium(III) were far lower for nicomorphine than heroin (approximately 5-fold for the samples that had not been hydrolysed). 相似文献
2.
3.
Haim Hacham Steven E. Freeman Richard W. Gange Daniel J. Maytum John C. Sutherland Betsy M. Sutherland † 《Photochemistry and photobiology》1990,52(4):893-896
A previous report [Freeman et al. (1986) Photochem. Photobiol. 43S, 93S] indicated that irradiation of human skin in situ with 385 or 405 nm radiation produced detectable levels of pyrimidine dimers in DNA. Since these wavelengths are absorbed poorly by DNA, these results suggested that DNA damage was sensitized by other absorbing molecules present in skin. Examination of two experimental aspects of the previous work indicates that (1) the static gel electrophoresis method for DNA dispersion used in lesion determination gave accurate values of the levels of induced dimers, and (2) the DNA damage apparently induced by 385 nm was actually induced by shorter wavelength UV present in the 20 nm bandpass beam of the monochromator. The current results indicate that monochromatic 385 and 405 nm radiation are ineffective in dimer production in human skin in situ. 相似文献
4.
PYRIMIDINE DIMER FORMATION IN HUMAN SKIN 总被引:1,自引:0,他引:1
Steven E. Freeman Richard W. Gange John C. Sutherland Betsy M. Sutherland 《Photochemistry and photobiology》1987,46(2):207-212
Cyclobutyl pyrimidine dimers are major photoproducts formed upon irradiation of DNA with ultraviolet light. We have developed a method for detecting as few as one pyrimidine dimer per million bases in about 50 ng of non-radioactive DNA, and have used this method to quantitate dimer yields in human skin DNA exposed in situ to UV. We found that UVA radiation (320–400 nm) produces detectable levels of dimers in the DNA of human skin. We also measured UVB-induced dimer yields in skin of individuals of differing sun sensitivity and found higher yields in individuals with higher UVB minimal erythema doses and greater sun sensitivity. These approaches should provide important information on damage induced in human skin upon exposure to natural or artificial sources of ultraviolet radiation. 相似文献
5.
6.
Abstract —The effect of irradiance on ultraviolet-induced delayed erythema was studied in normal human skin. With both UVB and UVC radiation, the minimal erythema dose was the same whether exposure lasted several seconds or 5 h. A reciprocal relationship between exposure duration and irradiance has previously been shown to exist for exposures ranging from nanoseconds to minutes. The present study shows that even if exposures last over 4 h the minimal erythema dose is a function of exposure dose and not of irradiance or exposure duration. 相似文献
7.
Manconi F Kable EP Dwarte D Jones A Russell P Chullapram T Gange PV Obeysekara S Thomas GA Fraser IS 《Micron (Oxford, England : 1993)》2011,42(8):853-862
There is increasing interest in the structure of the microvascular environment in human endometrium because of the recognition of the complexity and functional importance of this tissue. Endometrial microcirculatory networks and their relationships have rarely been studied in three-dimensions.Longitudinal uterine slices containing endometrial tissue were carefully selected from women undergoing a hysterectomy. Formalin-fixed endometrial sections (≤50 μm) representing the fundal and isthmic regions were immunofluorescently labeled with monoclonal antibody (CD34) to target the endothelium of microvessel and fluorescein isothiocyanate (FITC) labeled goat anti-mouse. Digital images were acquired using a Nikon Eclipse E800 microscope equipped with a Radiance 2000 confocal scanning laser attachment. ImarisBasic 4.1 visualization suite was utilized for qualitative interpretation. NeuronTracer 1.0 software was utilized to derive the length and numerical densities.There were significant changes across the phases of the menstrual cycle in functional and basal endometrial layers in vessel length density (LDv) and branch point density (NDv) within both fundal and isthmic regions of the uterus (P < 0.001). There was also a significant effect of menstrual cycle phase on mean vessel segment length (SLv) within each region and within each of the layers (P < 0.001). The capillary radial diffusion distance r(diff) was negatively correlated with LDv. In general, within each of the menstrual cycle phases, LDv, NDv were greater in the fundal than the isthmic regions while, in contrast, SLv was found to be greatest in the isthmic region.Utilization of immunofluorescence and laser scanning confocal microscopy has enabled us to demonstrate significant vascular changes in human endometrial layers illustrating that in general, within each of the menstrual cycle phases, vessel length and branch point densities were greater in the fundal than the isthmic regions, while vessel segment lengths were found to be greatest in the isthmic region. 相似文献
8.
Michelle Miller Francl Christina Carey Lisa Emily Chirlian David M. Gange 《Journal of computational chemistry》1996,17(3):367-383
The present work examines the conditioning of the least-squares matrix for obtaining potential derived charges and presents a modification of the CHELP method for fitting atomic charges to electrostatic potentials. Results from singular value decompositions (SVDs) of the least-squares matrices show that, in general, the least-squares matrix for this fitting problem will be rank deficient. Thus, statistically valid charges cannot be assigned to all the atoms in a given molecule. We find also that, contrary to popular notions, increasing the point density of the fit has little or no influence on the rank of the problem. Improvement in the rank can best be achieved by selecting points closer to the molecular surface. Basis set has, as expected, no effect on the number of charges that can be assigned. Finally, a well-defined, computationally efficient algorithm (CHELP-SVD) is presented for determining the rank of the least-squares matrix in potential-derived charge fitting schemes, selecting the appropriate subset of atoms to which charges can be assigned based on that rank estimate, and then refitting the selected set of charges. © 1996 by John Wiley & Sons, Inc. 相似文献
9.
Cheryl F. Rosen Steven L. Jacques† Mary E. Stuart Richard W. Gange 《Photochemistry and photobiology》1990,51(5):583-588
Immediate pigment darkening (IPD) occurs in human skin upon exposure to ultraviolet-A and visible radiation. The spectral changes that occur during IPD were measured with a rapid scanning reflectance spectrophotometer (RS) which employs optical fiber bundles for delivery and detection of light between 400 and 750 nm. The radiation dose dependence and wavelength dependence (334-549 nm irradiation) of IPD were studied by both the classical visual grading method and by spectrophotometric scoring using the RS system. The spectral changes that occur at long wavelengths with IPD mimic the natural absorption spectrum of melanin. Therefore, the IPD was scored in terms of the apparent change in melanin optical density, using the method Kollias and Baqer [Photochem. Photobiol. 43, 49-54 (1986)], based on reflectance in the 620-720 nm range. The nonlinearity of the visual grading method is demonstrated. The degree of IPD is first-order with respect to delivered dose and saturates after high doses. The maximum amount of IPD attained at saturation is greater for shorter wavelengths. Extrapolation of the reflectance data suggests the longest wavelength capable of eliciting IPD is about 470 nm. 相似文献
10.
Bernhard Ortel Daniel J. Maytum Richard W. Gange 《Photochemistry and photobiology》1991,54(4):645-650
Human skin can be persistently photosensitized by topical application of aqueous 8-methoxypsoralen plus immediate irradiation with a non-erythemogenic dose of wavelengths above 380 nm. Re-exposure of skin thus sensitized to broadband UV-A produces phototoxic erythema 72-120 h later. The persistence of the photosensitization was demonstrated by phototoxic erythema after re-exposure up to 15 days after the first sensitizing irradiation. According to the concept that the first exposure induces primarily psoralen monoadducts, we consider this an investigation of psoralen monoadduct persistence. In contrast to several earlier studies, this sensitive method indicates that psoralen monoadducts may remain in human skin in vivo for more than 2 weeks after formation. 相似文献