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21.
N. Cohen G. Weber B.L. Banner A.F. Welton W.C. Hope H. Crowley W.A. Anderson B.A. Simko M. O'Donnell J.W. Coffey C. Fiedler-Nagy C. Batula-Bernardo 《Prostaglandins & other lipid mediators》1984,27(4):553-562
The syntheses and biological activity of (all
)-7,7-dimethyl-5-8,- 11,14-eicosatetraenoic acid, (all
)-7,7,-dimethyl-5,8,11-eicosatrienoic acid, (
,
-7,7-dimethyl-5,8-eicosadienoic acid, (all
)-10,10-dimetyl- 5,8,11,14-eicosatetraenoic acid, (all
-10,10-dimethyl-5,8,11-eicosatrienoic acid, and
.-(
,
-15-hydroxy-7,7-dimethyl-5,8-eicosadienoic acid are described. These arachidonic acid analogs are all inhibitors of ionophore-induced SRS-A biosynthesis in rat peritoneal cells. Their mode of action may involve inhibition of phospholipase A2 rather than Δ5-lipoxygenase. These compounds failed to exhibit significant activity in an
model designed to detect inhibitors of antigen-induced, leukotriene-mediated bronchoconstriction is sensitized guinea pigs. 相似文献
22.
P H Crowley 《Journal of theoretical biology》1979,80(1):129-144
I have constructed a spatially distributed analytical model of predators, superior prey competitors, and inferior prey competitors, based on the limiting deterministic version of a simulation model by Caswell (1978). Persistence regions for the three populations are mapped in parameter space. Conceptually shrinking the system from infinite size (i.e. infinitely many spatial “cells”) to some finite size introduces demographic stochasticity, increasing the chance of extinction of one or more populations within a given time interval. But some of the finite (stochastic) system's behavior, such as any tendency to damp perturbations, can be related to the behavior of the deterministic system at the same location in parameter space. 相似文献
23.
24.
A method is developed for obtaining tree-structured relative risk estimates for censored survival data. The first step of a full likelihood estimation procedure is used in a recursive partitioning algorithm that adopts most aspects of the widely used Classification and Regression Tree (CART) algorithm of Breiman et al. (1984, Classification and Regression Trees, Belmont, California: Wadsworth). The performance of the technique is investigated through stimulation and compared to the tree-structured survival methods proposed by Davis and Anderson (1989, Statistics in Medicine 8, 947-961) and Therneau, Grambsch, and Fleming (1990, Biometrika 77, 147-160). 相似文献
25.
Collaborative experiments were conducted to determine whether microbial populations associated with plant roots may artifactually
affect the rates of Fe uptake and translocation from microbial siderophores and phytosiderophores. Results showed nonaxenic
maize to have 2 to 34-fold higher Fe-uptake rates than axenically grown plants when supplied with 1 μM Fe as either the microbial siderophore, ferrioxamine B (FOB), or the barley phytosiderophore, epi-hydroxymugineic acid (HMA).
In experiments with nonsterile plants, inoculation of maize or oat seedlings with soil microorganisms and amendment of the
hydroponic nutrient solutions with sucrose resulted in an 8-fold increase in FOB-mediated Fe-uptake rates by Fe-stressed maize
and a 150-fold increase in FOB iron uptake rates by Fe-stressed oat, but had no effect on iron uptake by Fe-sufficient plants.
Conversely, Fe-stressed maize and oat plants supplied with HMA showed decreased uptake and translocation in response to microbial
inoculation and sucrose amendment. The ability of root-associated microorganisms to affect Fe-uptake rates from siderophores
and phytosiderophores, even in short-term uptake experiments, indicates that microorganisms can be an unpredictable confounding
factor in experiments examining mechanisms for utilization of microbial siderophores or phytosiderophores under nonsterile
conditions. 相似文献
26.
Interactions among coexisting larval Odonata: an in situ experiment using small enclosures 总被引:1,自引:1,他引:0
Field experiments using small replicated enclosures focused on interactions between larval populations of Epitheca cynosura and Ladona deplanata (Odonata: Anisoptera) — two species that emerge in early spring. The presence of Epitheca reduced the total biomass of Ladona, but Ladona had no significant effect on Epitheca. These early-emerging species reduced the biomass of small instars of late-emerging Anisoptera which colonized enclosures
during the experiments; and the late-emerging Anisoptera seem to have inhibited colonization by Zygoptera larvae. Results
are consistent with the importance of predatory (cannibalism or mutual predation) interactions in this community. 相似文献
27.
Angie Rizzino Victor Terranova David Rohrbach Craig Crowley Heather Rizzino 《Journal of cellular biochemistry》1980,13(2):243-253
In this paper we have examined the growth and differentiation of the embryonal carcinoma cell line, F9, in the defined medium EM-3 at low density. We show that the growth of F9 and their differentiated cells (F9-diff) in EM-3 is strongly density dependent. At low cell densities the growth of both cell types is severely limited and most of the cells do not survive. Although this poses a problem for working with F9 and F9-diff in EM-3, it provides a convenient assay for identifying molecules that support their growth at low density. Using this assay, we have determined that laminin, a newly isolated glycoprotein of basement membranes, significantly improves the growth and short-term survival of both F9 and F9-diff. However, addition of laminin to EM-3 is insufficient to promote the clonal growth of these cell types. Our findings also indicate that laminin promotes the attachment of F9 and F9-diff in defined media. On the basis of our results, we propose an attachment function for laminin during the early stages of mammalian development. 相似文献
28.
Ultramafic (serpentine) soils from and adjacent to the Dun Mountain Ophiolitic Belt, South Island, New Zealand were analysed for 11 elements in order to establish to what degree edaphic factors influenced the character of the overlying vegetation. Using principal components analysis with a mutual plot of the first two principal components, involving the total elemental concentrations in the soils, it was possible to divide the soils into 6 virtually non-overlapping fields, each of which represented a specific vegetation community. Component 1 was essentially an ultramafic plot with heavy loadings from the elements chromium, cobalt, iron, magnesium, manganese, and nickel. Component 2 was a non ultramafic plot with heavy loadings from aluminium, copper and zinc. For elements extracted from the soils at pH 5.9, discrimination was somewhat poorer but confirmed the great importance of magnesium and nickel as controlling elements for the serpentine vegetation. It was concluded that the results indicated the overriding importance of edaphic factors in controlling the serpentine vegetation. 相似文献
29.
Elke EM Brouwers Alwin DR Huitema Jos H Beijnen Jan HM Schellens 《BMC clinical pharmacology》2008,8(1):7
Background
The aim of this study was to evaluate long-term platinum retention in patients treated with cisplatin and oxaliplatin. 相似文献30.