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排序方式: 共有765条查询结果,搜索用时 15 毫秒
1.
2.
A H Uggla 《Mutation research》1988,201(1):229-239
A comparison has been made between the ability of different acridine compounds to act as sensitizers for visible light (400-700 nm) induced chromosomal aberrations and sister-chromatid exchanges (SCE) in unsynchronized Chinese hamster ovary (CHO) cells. Cells were treated for 20 min with acridines (0.1-5.0 microgram/ml), washed free of excess dye and subsequently exposed to visible light (2 x 40 W/8 W m-2) either in air or in nitrogen for 5-15 min. The 4 acridines tested, proved to be effective sensitizers for the induction of both chromosomal aberrations and SCE by visible light. The most pronounced effect was observed when the light exposure of the fluorochrome-pretreated cells was performed in air. Hypoxic conditions during light exposure reduced the effect dramatically, especially in the case of induced chromosomal aberrations. The order of efficiency for the induction of both chromosomal aberrations and SCE was acridine orange greater than acridine yellow greater than proflavine greater than 3,6-diamino-10-methylacridine. The results are discussed in terms of S-independent versus S-dependent mechanisms for inducing chromosomal alterations and the potential involvement of oxygen-derived free radicals in this process. 相似文献
3.
A nasal, so called ethmoidal, tumor from a fallow deer is described. It appears to be the first reported case of that species. The etiology is discussed. 相似文献
4.
Ralf Morgenstern Claes Guthenberg Bengt Mannervik Joseph W. DePierre 《FEBS letters》1983,160(1-2):264-268
The amount and nature of glutathione transferases in rat liver microsomes were determined using immunological techniques. It was shown that cytosolic glutathione transferase subunits A plus C, and B plus L were present at levels of 2.4 ± 0.6 and 1.5 ± 0.1 μg/mg microsomal protein, respectively. These levels are 10-times higher than those for non-specific binding of cytosolic components judging from the distribution of lactate dehydrogenase, a cytosolic marker. The possibility that a portion of these glutathione transferases is functionally localized on the endoplasmic reticulum is discussed. A previously described microsomal glutathione transferase which is distinct from the cytosolic enzymes is present in an amount of 31 ± 6 μg/mg microsomal protein. 相似文献
5.
6.
Claes Rüdeberg 《Cell and tissue research》1967,84(2):219-237
Summary The pineal organ of the sardine, Sardina pilchardus sardina, was investigated light and electron microscopically. The pineal parenchyma contains sensory cells, supporting cells, and ganglion cells, and the overlying tissues appear specialized for light penetration. The ganglion cells are arranged in 3 groups, their axons giving rise to the tractus epiphyseos. The sensory cell is of a photoreceptor type found in several other teleost species. No definitive evidence of a secretion was educed but some indications of an endocrine function are reported and discussed.The pineal receptor cell of neonates of Mugil spp. which have a pigment-free spot above the pineal organ, was investigated electron microscopically and found to have the same organization as that of adult Mugil auratus.Supported by grants from the Helge Ax:son Johnsons Stiftelse, Stockholm, and from the Kungliga Vetenskapsakademien, Stockholm, Sweden. This is gratefully acknowledged.The animal material has been provided by the Stazione Zoologica di Napoli. 相似文献
7.
As fresh human cadaveric spine specimens for in vitro testing are hard to obtain and carry a potential risk of infection, the possibility of using embalmed spine specimens has been considered. The cross-linking effect of formalin fixation, however, raises uncertainties regarding the biomechanical likeness of preserved specimens. They have been reported to be stiffer, but no quantitative data exist.
The purpose of this study was to determine the biomechanical differences between fresh and formalin-fixed spine specimens, using L1–2 motion segments from six 16-week-old calf spines. The range of motion and neutral zone were determined in flexion-/extension, left/right axial rotation, and right/left lateral bending.
The range of motion decreased in the formalin fixed specimens by as much as 80%, and the neutral zone by as much as 96%. The results of this study therefore imply that, for biomechanical testing, formalin-fixed specimens are not representative of the in vivo conditions. 相似文献
8.
Neospora caninum is a recently recognized protozoan organism that causes fatal neuromuscular disease in dogs and abortions and stillbirths in cattle and other animals (Dubey & Lindsay 1993). The parasite is morphologically similar and phylogenetically very closely related to the cyst-forming coccidium Toxoplasma gondii (Ellis et al. 1994, Holmdahl et al. 1994). This group of parasites has a two-host life cycle principally involving a carnivorous definitive host and a herbivorous or omnivorous intermediate host. However, with N. caninum, there is as yet no knowledge of any definitive host harbouring sexual stages of the parasite. The only known route of transmission is vertical from mother to foetus (Dubey & Lindsay 1993). 相似文献
9.
Concentrations of Amino Acids in Extracellular Fluid After Opening of the Blood-Brain Barrier by Intracarotid Infusion of Protamine Sulfate 总被引:3,自引:0,他引:3
Irena Westergren Britta Nystrom ers Hamberger Claes Nordborg Barbro B. Johansson 《Journal of neurochemistry》1994,62(1):159-165
Abstract: This article evaluates the influence of an opening of the blood-brain barrier (BBB) on compounds in brain extracellular fluid. The concentrations of amino acids and some other primary amines were determined in dialysates sampled from the right parietal cortex of rats before and after an intracarotid infusion of protamine sulfate. Extravasated plasma proteins were visualized by Evans blue/albumin and immunohistochemistry. CSF albumin— an indicator of blood-CSF barrier opening—was quantified with immunoelectrophoresis. The brains were macroscopically edematous after 10 mg but not after 5 mg of protamine sulfate. The higher dose led to a 50% death rate. The concentrations of amino acids did not change 10 min after the BBB opening. No significant alterations in the amino acid concentrations were observed after the lower dose. The concentrations of glutamate, aspartate, GABA, glycine, taurine, and phosphoethanolamine increased significantly within 50–80 min after the infusion of 10 mg of protamine sulfate. CSF albumin levels were significantly increased 1 h after infusion. We conclude that a dysfunction of the BBB, of a degree known to induce brain edema (10 mg of protamine sulfate), significantly increases the extracellular concentration of excitatory amino acids, GABA, taurine, and phosphoethanolamine in the extracellular space. 相似文献
10.
Viacheslav Katerov Claes Schalén Artem A. Totolian 《Molecular & general genetics : MGG》1994,245(1):78-85
Major virulence determinants of group A streptococci, such as M-protein, immunoglobulin Fc-receptors (FcRA, EmmL) and C5a peptidase, appear to be genetically co-regulated, their genes being located within a vir regulon. We studied the organization of these genes in a group A, type M15 strain of Streptococcus pyogenes, previously defined as OF–, by hybridization analysis of chromosomal DNA and of an S. pyogenes gene library in Escherichia coli, and by gene sequencing. Within the vir regulon, in addition to the virR and scpA genes, three so-called emm-related genes were found: fcrA, emmL and enn. Whereas IgG Fc-binding proteins were encoded by fcrA and emmL, the product of enn was not identified. The presence of three emm-related genes in this region is reminescent of vir regulon organization in OF+ rather than OF– strains as earlier defined by others. Furthermore, analysis of the deduced product of the emmL gene showed deletions and amino acid substitutions within the PGTS-rich domain and membrane anchor, which thus resembles corresponding products of OF+ rather than OF– strains. In view of these findings, the opacity factor (OF) activity of the strain was tested using growth supernatant, with negative outcome. However, a concentrated SDS cell extract revealed definite OF activity. One of two other type M15 reference strains also showed definite OF activity in SDS extracts. We therefore propose that type M15 strains belong to the OF+ category but often show low levels of expression of OF. 相似文献