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排序方式: 共有137条查询结果,搜索用时 187 毫秒
71.
White FJ Burghardt RC Hu J Joyce MM Spencer TE Johnson GA 《Reproduction (Cambridge, England)》2006,132(6):919-929
Secreted phosphoprotein 1 (SPP1, osteopontin) is the most highly upregulated extracellular matrix/adhesion molecule/cytokine in the receptive phase human uterus, and Spp1 null mice manifest decreased pregnancy rates during mid-gestation as compared with wild-type counterparts. We hypothesize that Spp1 is required for proliferation, migration, survival, adhesion, and remodeling of cells at the conceptus-maternal interface. Our objective was to define the temporal/spatial distribution and steroid regulation of Spp1 in mouse uterus during estrous cycle and early gestation. In situ hybridization localized Spp1 to luminal epithelium (LE) and immune cells. LE expression was prominent at proestrus, decreased by estrus, and was nearly undetectable at diestrus. During pregnancy, Spp1 mRNA was not detected in LE until day 4.5 (day 1 = vaginal plug). Spp1-expressing immune cells were scattered within the endometrial stroma throughout the estrous cycle and early pregnancy. Immunoreactive Spp1 was prominent at the apical LE surface by day 4.5 of pregnancy and Spp1 protein was also co-localized with subsets of CD45-positive (leukocytes) and F4/80-positive (macrophages) cells. In ovariectomized mice, estrogen, but not progesterone, induced Spp1 mRNA, whereas estrogen plus progesterone did not induce Spp1 in LE. These results establish that estrogen regulates Spp1 in mouse LE and are the first to identify macrophages that produce Spp1 within the peri-implantation endometrium of any species. We suggest that Spp1 at the apical surface of LE provides a mechanism to bridge conceptus to LE during implantation, and that Spp1-positive macrophages within the stroma may be involved in uterine remodeling for conceptus invasion. 相似文献
72.
Knowledge of the various cues that elicit natural behavior is important to our understanding of why and when animals behave as they do. In order to gain insight into the behavior and ecology of Nerodia clarkii compressicauda, a piscivorous snake that uses a unique form of predatory luring as a foraging tactic, we observed 22 juvenile subjects in the presence of visual and chemical prey stimuli in a repeated-measures design. The use of video playback as a visual stimulus in this experiment permitted complete isolation from tactile and chemical cues. Snakes were more sedentary and used lingual luring more when both cue types were present than when none or only one of the cues was available. Subjects also attacked more often in the presence of both stimuli. Predatory attacks by prey-na?ve subjects directed to video cues when only visual prey stimuli were available demonstrated that snakes can identify prey visually without prior experience. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
73.
Comments on P. McReynolds's (see record 1988-03153-001) discussion of L. Witmer's role in clinical psychology, noting that Witmer (1909, 1910) also made contributions to comparative psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
74.
Chapkin RS Hong MY Fan YY Davidson LA Sanders LM Henderson CE Barhoumi R Burghardt RC Turner ND Lupton JR 《Lipids》2002,37(2):193-199
There is experimental evidence that dietary fish oil, which contains the n−3 fatty acid family, i.e., EPA and DHA, protects
against colon tumor development, in part by increasing apoptosis. Since mitochondria can act as central executioners of apoptosis,
we hypothesized that EPA and DHA incorporation into colonocyte mitochondrial membranes, owing to their high degree of unsaturation,
would enhance susceptibility to damage by reactive oxygen species (ROS) generated via oxidative phosphorylation. This, in turn, would compromise mitochondrial function, thereby initiating apoptosis. To test
this hypothesis, colonic crypts were isolated from rats fed either fish oil, purified n−3 fatty acid ethyl esters, or corn
oil (control). Dietary lipid source had no effect on colonic mitochondrial phospholipid class mole percentages, although incorporation
of EPA and DHA was associated with a reduction in n−6 fatty acids known to enhance colon tumor development, i.e., linoleic
acid (LNA) and its metabolic product, arachidonic acid (ARA). Select compositional changes in major phospholipid pools were
correlated to alterations in mitochondrial function as assessed by confocal microscopy. The mol% sum of LNA plus ARA in cardiolipin
was inversely correlated with ROS (P=0.024). Ethanolamine glycerophospholipid ARA (P=0.046) and choline glycerophospholipid INA (P=0.033) levels were positively correlated to mitochondrial membrane potential. In contrast, ethanolamine glycerophospholipid
EPA (P=0.042) and DHA (P=0.024), levels were negatively correlated to mitochondrial membrane potential. Additionally, EPA and DHA levels in choline
glycerophospholipids (P=0.026) were positively correlated with caspase 3 activity. These data provide evidence in vivo indicating that dietary FPA and DHA induce compositional changes in colonic mitochondrial membrane phospholipids that facilitate
appotosis. 相似文献
75.
Allen Barbara A.; Burghardt Gordon M.; York Daniel S. 《Canadian Metallurgical Quarterly》1984,98(4):358
Tested isolation-reared sympatric water snakes (Nerodia r. rhombifera, N. c. cyclopion, and N. fasciata confluens) in a balanced 2-choice design to determine preference between clean and same-sex conspecific-soiled gravel substrates. Ss included 8 snakes (4 of each sex) of each species. Time spent on each substrate, types of tongue flicking behavior, tail vibration, defecation, and head rubbing were recorded. Species and sex differences were found in the relative time spent on the 2 substrates. Both sexes of N. rhombifera preferred the clean substrate, whereas both sexes of N. cyclopion preferred the soiled substrate, although the difference in time spent on the substrates was small for males. N. fasciata sexes differed in their preference, with the females preferring the soiled substrate and the males preferring, but not so strongly, the clean substrate. The frequencies of the 4 types of tongue extensions differed across species and sexes, with "air" tongue flicks accounting for the most variance. A lower total rate of tongue flicking occurred when the snakes were on the preferred substrate. These species and sex differences may help minimize competition due to dietary overlap between N. rhombifera and N. cyclopion, and between male and female N. fasciata. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
76.
Materials eliciting increased tongue flicking and prey attack in garter snakes were isolated from both earthworm and fish prey. New extraction methods based on chloroform-methanol mixtures are valuable adjuncts to the more typical aqueous preparations. Both high- and low-molecular weight components from earthworms and fish were active. The similarity between the active chemicals in these two classes of prey was established using several methods of analysis. These included chromatography, carbohydrate and amino acid analyses, and nuclear magnetic resonance. 相似文献
77.
K Bellmann H Kolb B Hartmann H Rothe P Rowsell S Rastegar K Burghardt FW Scott 《Canadian Metallurgical Quarterly》1997,19(9-10):573-577
BB rats and nonobese diabetic (NOD) mice spontaneously develop autoimmune insulin dependent diabetes and serve as models for human type I diabetes. During progression of the disease the cytokine pattern elaborated by islet infiltrating immune cells shifts from a Th2 or Th0 toward Th1 type. Only the latter is associated with "destructive" insulitis. We discuss here attempts to modulate disease progression by targeting the gut immune system with bacterial immunostimulants. Oral dosing of diabetes prone BB rats with lipopolysaccharide (LPS) or the Escherichia coli extract OM-89 lead to a Th2-shift of pancreatic mRNA expression. In vitro studies showed that repeated exposure toward LPS or OM-89 lead to downregulation of proinflammatory macrophage responses. In the NOD mouse, repeated oral dosing of OM-89 caused a Th2 shift in the gut cytokine gene expression, probably because of desensitization of macrophages and other antigen presenting cells. Concomitantly, diabetes prevention by oral insulin was improved. In conclusion, oral dosing with bacterial immunostimulants dampens Th1 type immune reactivities of the gut immune system and thereby promotes oral tolerance mechanisms. Downregulation of proinflammatory immune reactivities by repeated exposure to bacterial stimulants requires intact desensitization mechanisms in macrophages or other antigen presenting cells. 相似文献
78.
Integrating ontological modelling and Bayesian inference for pattern classification in topographic vector data 总被引:1,自引:0,他引:1
Patrick Lüscher Robert Weibel Dirk Burghardt 《Computers, Environment and Urban Systems》2009,33(5):363
This paper presents an ontology-driven approach for spatial database enrichment in support of map generalisation. Ontology-driven spatial database enrichment is a promising means to provide better transparency, flexibility and reusability in comparison to purely algorithmic approaches. Geographic concepts manifested in spatial patterns are formalised by means of ontologies that are used to trigger appropriate low level pattern recognition techniques. The paper focuses on inference in the presence of vagueness, which is common in definitions of spatial phenomena, and on the influence of the complexity of spatial measures on classification accuracy. The concept of the English terraced house serves as an example to demonstrate how geographic concepts can be modelled in an ontology for spatial database enrichment. Owing to their good integration into ontologies, and their ability to deal with vague definitions, supervised Bayesian inference is used for inferring complex concepts. The approach is validated in experiments using large vector datasets representing buildings of four different cities. We compare classification results obtained with the proposed approach to results produced by a more traditional ontology approach. The proposed approach performed considerably better in comparison to the traditional ontology approach. Besides clarifying the benefits of using ontologies in spatial database enrichment, our research demonstrates that Bayesian networks are a suitable method to integrate vague knowledge about conceptualisations in cartography and GIScience. 相似文献
79.
Three populations of the water snake,Natrix s. sipedon, were tested for their responses to surface water extracts prepared from various prey species. It was clearly shown that these snakes can distinguish between different prey genera on the basis of chemical cues alone. Adult snakes caught at a fish hatchery where goldfish (Carassius auratus) were abundant responded most to goldfish extract, as did laboratory-born snakes reared on goldfish for one year. However, snakes caught in a relatively undisturbed mountain stream environment and naive young born to a mountain female responded more to the extracts of various sympatric-mountain fish and amphibians. The evidence indicates that newborn snakes have genetic predispositions for sympatric species of the classes of prey normally eaten. These preferences can be enhanced or inhibited during ontogeny. 相似文献
80.
Thorben Sauer Giulia Facchinetti Michael Kohl Justyna M. Kowal Svitlana Rozanova Julia Horn Hagen Schmal Ivo Kwee Arndt-Peter Schulz Sonja Hartwig Moustapha Kassem Jens K. Habermann Timo Gemoll 《International journal of molecular sciences》2022,23(5)
Mesenchymal stem cells (MSCs) gain an increasing focus in the field of regenerative medicine due to their differentiation abilities into chondrocytes, adipocytes, and osteoblastic cells. However, it is apparent that the transformation processes are extremely complex and cause cellular heterogeneity. The study aimed to characterize differences between MSCs and cells after adipogenic (AD) or osteoblastic (OB) differentiation at the proteome level. Comparative proteomic profiling was performed using tandem mass spectrometry in data-independent acquisition mode. Proteins were quantified by deep neural networks in library-free mode and correlated to the Molecular Signature Database (MSigDB) hallmark gene set collections for functional annotation. We analyzed 4108 proteins across all samples, which revealed a distinct clustering between MSCs and cell differentiation states. Protein expression profiling identified activation of the Peroxisome proliferator-activated receptors (PPARs) signaling pathway after AD. In addition, two distinct protein marker panels could be defined for osteoblastic and adipocytic cell lineages. Hereby, overexpression of AEBP1 and MCM4 for OB as well as of FABP4 for AD was detected as the most promising molecular markers. Combination of deep neural network and machine-learning algorithms with data-independent mass spectrometry distinguish MSCs and cell lineages after adipogenic or osteoblastic differentiation. We identified specific proteins as the molecular basis for bone formation, which could be used for regenerative medicine in the future. 相似文献