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排序方式: 共有258条查询结果,搜索用时 15 毫秒
101.
R D Lloyd C W Jones C W Mays D R Atherton F W Bruenger G N Taylor 《Radiation research》1984,98(3):614-628
Total-body and skeletal retention of 228Th were determined in a group of 104 young adult male and female beagles for about the first 7 years after the injection of 0.00159 to 2.76 muCi/kg. Ratios of 224Ra / 228Th , 212Pb / 228Th , and 212Bi / 228Th in the skeleton and in soft tissues of 20 beagles were measured as a function of time after injection. A humerus, femur, and ulna from 20 dogs dying 7 to 554 days after injection were sectioned, and the 228Th concentration was obtained for each piece. Percentage biological retention in the skeleton of 228Th at t days after injection could be described as 68.1 e-0. 000180t . Ratios of daughter-to-parent activity in soft tissue showed no definite trend with dose level or time and averaged Ra/Th = 0.56, Pb/Th = 0.83, and Bi/Th = 0.91, whereas the ratios for the skeleton varied with both dose level and time. Ratios of activity in the skeleton from lowest to highest dose level after 2 years following injection ranged between Ra/Th = 0.88 to 0.95, Pb/Th = 0.78 to 0.92, and Bi/Th = 0.77 to 0.90. Retained 228Th was deposited most heavily in parts of the skeleton with much trabecular bone, much bone surface area, and high bone remodeling rates. No changes in this deposition pattern could be discerned during the 554 days over which the measurements of sectioned long bones were made. 相似文献
102.
Protection of mice from herpes simplex virus-induced retinitis by in vitro-activated immune cells. 总被引:3,自引:2,他引:1 下载免费PDF全文
J U Igietseme P J Calzada A R Gonzalez J W Streilein S S Atherton 《Journal of virology》1989,63(11):4808-4813
A form of acute retinal necrosis occurred in the contralateral eyes of susceptible mice 1 week after each received a uniocular injection of live herpes simplex virus type 1 (HSV-1) in the anterior chamber. Although these mice did not develop systemic delayed hypersensitivity to virus antigens, their sera contained virus-specific antibodies at the time contralateral retinitis occurred. These findings suggest that systemic immunity might not be able to protect against contralateral retinitis. To explore this possibility further, we examined lymph nodes and spleens of intraocularly infected mice to determine whether their lymphoid tissues contained primed HSV-1-specific cytotoxic T cells. Virus-specific cytotoxic T cells were readily identified in these mice. We wondered why successful immune priming did not confer protection against HSV-1 retinitis. We examined this issue by evaluating the capacity of in vitro-generated, HSV-1-specific effector T cells to prevent retinitis by infusing these cells by various routes and at various times into mice that received an intracameral injection of HSV-1. The results revealed that virus-specific effector cells could prevent contralateral retinitis if injected intravenously or into the anterior chamber of the contralateral eye at the same time that virus was injected into one eye. However, the effector cells failed to prevent retinitis if they were injected into the same eye that received HSV-1 or if their intravenous administration was delayed until 24 h after the HSV-1 injection into the eye. We concluded that immune T cells can protect against contralateral retinal necrosis caused by uniocular injection of HSV-1 into the anterior chamber but only if they are administered during the first 24 h after virus infection. We propose that a retinitis-inducing process is set in motion during this early time interval postinfection. Once the process has been initiated and established, it is no longer susceptible to immune intervention. It would appear that mice that are susceptible to contralateral retinitis fail to mobilize a protective response quickly enough to ward off the establishment of the retinitis-inducing process and its disastrous eventuality. 相似文献
103.
R. D. Lloyd C. W. Mays D. R. Atherton G. N. Taylor 《Radiation and environmental biophysics》1976,13(3):229-237
Summary Bremsstrahlung x-rays are produced when energetic-particles are emitted and absorbed. Measurements of total-body bremsstrahlung efficiency (x-ray photon output per Ci90Sr in the body, relative to that in water) have been made in the intact mouse, rat, rabbit, and dog sacrificed 2 weeks after the injection of90Sr +85Sr. Efficiencies were determined by a comparison of the bremsstrahlung output from90Sr + its daughter90Y and the gamma-ray emission of85Sr. Results were checked by a-assay of the ashed animals. Bremsstrahlung efficiencies averaged 1.10 in a 0.04 kg mouse, 1.14 in a 0.13 kg rat, 1.23 in a 2.6 kg rabbit, and 1.32 in an 8.5 kg beagle. Extrapolating to a 70 kg human, a relative bremsstrahlung efficiency of about 1.4 is predicted. An estimate was made of the90Sr body content in a former dial painter based on in vivo counting and a bremsstrahlung efficiency of 1.39 predicted for a 55 kg human female by these animal data. Our value of 1.42 ± 0.08 Ci90Sr was in good agreement with corresponding results reported for this subject by 8 other laboratories.Supported by USERDA Contract E (11-1)-119 相似文献
104.
105.
Metabolism of c-myc gene products: c-myc mRNA and protein expression in the cell cycle. 总被引:24,自引:6,他引:18 下载免费PDF全文
P H Rabbitts J V Watson A Lamond A Forster M A Stinson G Evan W Fischer E Atherton R Sheppard T H Rabbitts 《The EMBO journal》1985,4(8):2009-2015
The presence and synthesis of c-myc protein and mRNA in the cell cycle has been studied. We find that c-myc mRNA is present, at equivalent levels, at all times in the cell cycle with the possible exception of mitosis. Furthermore, we demonstrate that this mRNA is transcribed in both G1 and G2 phases. An analysis of the c-myc protein in vivo shows that de novo synthesis occurs in G1 and G2 and the protein turns over with a half-life of approximately 20-30 min in both phases. Furthermore, the level of c-myc protein rapidly increases in cell populations when they re-initiate the cell cycle, thereafter decreasing as the culture reaches quiescence. The results therefore suggest that expression of c-myc can be rapidly modulated and that it is activated during the G0 to G1 transition, but is expressed thereafter in the cell cycle. 相似文献
106.
R. W. Atherton C. M. Cisson B. W. Wilson T. K. Golder 《Molecular reproduction and development》1980,3(1):17-24
The hypothesis that motility of avian sperm is regulated by acetylcholine was examined by treating rooster (Gallus domesticus) sperm with choline analogs and paraoxon, an inhibitor of colonesterases. Acetylcholine chloride (AChCl) was most effective, acetylthiocholine iodide and butyrylthiocholine iodide were less effective, and choline chloride was ineffective in stimulating sperm motility. Histochemical localization of cholinesterase activity with the electron microscope showed enzyme activity to be associated with membranes of the head and within fibrillar components of the tail. Increasing concentrations of paraoxon decreased cholinesterase activity and increased sperm motility. The data provide evidence that the motility of avian sperm, like that of mammal and sea urchins, may be regulated in part by a system with similarities to the cholinergic neurotransmitter system. 相似文献
107.
Stevenson CS Coote K Webster R Johnston H Atherton HC Nicholls A Giddings J Sugar R Jackson A Press NJ Brown Z Butler K Danahay H 《American journal of physiology. Lung cellular and molecular physiology》2005,288(3):L514-L522
Repetitive, acute inflammatory insults elicited by cigarette smoke (CS) contribute to the development of chronic obstructive pulmonary disease (COPD), a disorder associated with lung inflammation and mucus hypersecretion. Presently, there is a poor understanding of the acute inflammatory mechanisms involved in this process. The aims of this study were to develop an acute model to investigate temporal inflammatory changes occurring after CS exposure. Rats were exposed to whole body CS (once daily) generated from filtered research cigarettes. Initial studies indicated the generation of a neutrophilic/mucus hypersecreting lung phenotype in <4 days. Subsequent studies demonstrated that just two exposures to CS (15 h apart) elicited a robust inflammatory/mucus hypersecretory phenotype that was used to investigate mechanisms driving this response. Cytokine-induced neutrophil chemoattractants (CINCs) 1-3, the rat growth-related oncogene-alpha family homologs, and IL-1beta demonstrated time-dependent increases in lung tissue or lavage fluid over the 24-h period following CS exposure. The temporal changes in the neutrophil chemokines, CINCs 1-3, mirrored increases in neutrophil infiltration, indicative of a role in neutrophil migration. In addition, a specific CXCR2 antagonist, SB-332235, effectively inhibited CS-induced neutrophilia in a dose-dependent manner, supporting this conclusion. This modeling of the response of the rat airways to acute CS exposure indicates 1) as few as two exposures to CS will induce a phenotype with similarities to COPD and 2) a novel role for CINCs in the generation of this response. These observations represent a paradigm for the study of acute, repetitive lung insults that contribute to the development of chronic disease. 相似文献
108.
109.
Atherton Philip J. Higginson James M. Singh Jaipaul Wackerhage Henning 《Molecular and cellular biochemistry》2004,261(1):111-116
Differences in the concentrations of signal transduction proteins often alter cellular function and phenotype, as is evident from numerous, heterozygous knockout mouse models for signal transduction proteins. Here, we measured signal transduction proteins involved in the adaptation to exercise and insulin signalling in fast rat extensor digitorum longus (EDL; 3% type I fibres) and the slow soleus muscles (84% type I fibres). The EDL and soleus were excised from four rats, the proteins extracted and subjected to Western blots for various signal transduction proteins. Our results show major differences in signal transduction protein concentrations between EDL and soleus. The EDL to soleus concentration ratios were: Calcineurin: 1.43 ± 0.10; ERK1: 0.38 ± 0.18; ERK2: 0.61 ± 0.16; p38, : 1.36 ± 0.15; p38/ERK6: 0.95 ± 0.11; PKB/AKT: 1.44 ± 0.08; p70S6k: 6.86 ± 3.58; GSK3: 0.69 ± 0.03; myostatin: 1.95 ± 0.43; NF-B: 0.32 ± 0.10 (values >1 indicate higher expression in the EDL, and values <1 indicate higher expression in the soleus). With the exception of p38/ERK6, the concentration of each signal transduction protein was uniformly higher in one muscle than in the other in all four animals. These experiments show that signal transduction protein concentrations vary between fast and slow muscles, presumably reflecting a concentration difference on a fibre level. Proteins that promote particular functions such as growth or slow phenotype are not necessarily higher in muscles with that particular trait (e.g. higher in larger fibres or slow muscle). Interindividual differences in fibre composition might explain variable responses to training and insulin. (Mol Cell Biochem 261: 111–116, 2004) 相似文献
110.
The phylogenetic position of the Pedetidae, represented by a single species
Pedetes capensis, is controversial, reflecting in part the retention of
both Hystricomorphous and Sciurognathous characteristics in this rodent. In
an attempt to clarify the species evolutionary relationships, mtDNA gene
sequences from 10 rodent species (representing seven families) were
analyzed using phenetic, parsimony, and maximum-likelihood methods of
phylogenetic inference; the rabbit, Oryctolagus cuniculus (Order
Lagomorpha), and cow, Bos taurus (Order Artiodactyla), were used as
outgroups. Investigation of 714 base pairs of the protein-coding cytochrome
b gene indicate strong base bias at the third codon position with
significant rate heterogeneity evident between the three structural domains
of this gene. Similar analyses conducted on 816 base pairs of the 12S rRNA
gene revealed a transversion bias in the loop sections of all taxa. The
cytochrome b gene sequences proved useful in resolving associations between
closely related species but failed to produce consistent tree topologies at
the family level. In contrast, phylogenetic analysis of the 12S rRNA gene
resulted in strong support for the clustering of
Pedetidae/Heteromyidae/Geomyidae and Muridae in one clade to the exclusion
of the Hystricidae/Thryonomyidae and Sciuridae, a finding which is
concordant with studies of rodent fetal membranes as well as reproductive
and other anatomical features.
相似文献