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11.
Dendritic depolarization, which seems to be involved in the induction of long-term potentiation (LTP), was elicited by localized glutamate application. When paired to low frequency synaptic activation in the same area, the subsequent changes had features in common with LTP, expressed as an increased probability of firing and shorter spike latency. The EPSP was not significantly increased. 相似文献
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Protein kinase C injection into hippocampal pyramidal cells elicits features of long term potentiation 总被引:9,自引:0,他引:9
G Y Hu O Hvalby S I Walaas K A Albert P Skjeflo P Andersen P Greengard 《Nature》1987,328(6129):426-429
Long-term potentiation (LTP) in the hippocampus is an interesting example of synaptic plasticity because of its induction by physiological discharge rates and its long duration. Of the possible biochemical mechanisms that regulate prolonged changes in cell function, protein phosphorylation is a particularly attractive candidate. We have therefore examined the effect of intracellular injection of calcium/diacylglycerol-dependent protein kinase (protein kinase C (PKC] in CA1 pyramidal neurones in hippocampal slices. Injection of the active enzyme elicited long-lasting enhancement of synaptic transmission, similar to LTP, whereas inactivated kinase failed to do so. The observed changes included an increased amplitude of the excitatory post-synaptic potential (e.p.s.p.) and an increased probability of firing and a reduced latency of the associated actin potential. 相似文献
14.
S. Makridakis A. Andersen R. Carbone R. Fildes M. Hibon R. Lewandowski J. Newton E. Parzen R. Winkler 《Journal of forecasting》1982,1(2):111-153
In the last few decades many methods have become available for forecasting. As always, when alternatives exist, choices need to be made so that an appropriate forecasting method can be selected and used for the specific situation being considered. This paper reports the results of a forecasting competition that provides information to facilitate such choice. Seven experts in each of the 24 methods forecasted up to 1001 series for six up to eighteen time horizons. The results of the competition are presented in this paper whose purpose is to provide empirical evidence about differences found to exist among the various extrapolative (time series) methods used in the competition. 相似文献
15.
H. Shio P. W. Ramwell N. H. Andersen E. J. Corey 《Cellular and molecular life sciences : CMLS》1970,26(4):355-357
Zusammenfassung Die stereochemischen Voraussetzungen der Prostaglandin-15-Dehydrogenase aus Schweinelunge werden im Hinblick auf die pharmakologische Aktivität anhand einer Reihe synthetischer Prostaglandin E1-Präparate abgeklärt.
This work was supported by grants from the U.S. National Institutes of Health to Harvard University and by O.N.R. and N.I.H. grants to the Worcester Foundation for Experimental Biology. 相似文献
This work was supported by grants from the U.S. National Institutes of Health to Harvard University and by O.N.R. and N.I.H. grants to the Worcester Foundation for Experimental Biology. 相似文献
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17.
Changing Arctic Ocean freshwater pathways 总被引:7,自引:0,他引:7
Freshening in the Canada basin of the Arctic Ocean began in the 1990s and continued to at least the end of 2008. By then, the Arctic Ocean might have gained four times as much fresh water as comprised the Great Salinity Anomaly of the 1970s, raising the spectre of slowing global ocean circulation. Freshening has been attributed to increased sea ice melting and contributions from runoff, but a leading explanation has been a strengthening of the Beaufort High--a characteristic peak in sea level atmospheric pressure--which tends to accelerate an anticyclonic (clockwise) wind pattern causing convergence of fresh surface water. Limited observations have made this explanation difficult to verify, and observations of increasing freshwater content under a weakened Beaufort High suggest that other factors must be affecting freshwater content. Here we use observations to show that during a time of record reductions in ice extent from 2005 to 2008, the dominant freshwater content changes were an increase in the Canada basin balanced by a decrease in the Eurasian basin. Observations are drawn from satellite data (sea surface height and ocean-bottom pressure) and in situ data. The freshwater changes were due to a cyclonic (anticlockwise) shift in the ocean pathway of Eurasian runoff forced by strengthening of the west-to-east Northern Hemisphere atmospheric circulation characterized by an increased Arctic Oscillation index. Our results confirm that runoff is an important influence on the Arctic Ocean and establish that the spatial and temporal manifestations of the runoff pathways are modulated by the Arctic Oscillation, rather than the strength of the wind-driven Beaufort Gyre circulation. 相似文献
18.
IJ Simpson MP Sulbaek Andersen S Meinardi L Bruhwiler NJ Blake D Helmig FS Rowland DR Blake 《Nature》2012,488(7412):490-494
After methane, ethane is the most abundant hydrocarbon in the remote atmosphere. It is a precursor to tropospheric ozone and it influences the atmosphere's oxidative capacity through its reaction with the hydroxyl radical, ethane's primary atmospheric sink. Here we present the longest continuous record of global atmospheric ethane levels. We show that global ethane emission rates decreased from 14.3 to 11.3 teragrams per year, or by 21 per cent, from 1984 to 2010. We attribute this to decreasing fugitive emissions from ethane's fossil fuel source--most probably decreased venting and flaring of natural gas in oil fields--rather than a decline in its other major sources, biofuel use and biomass burning. Ethane's major emission sources are shared with methane, and recent studies have disagreed on whether reduced fossil fuel or microbial emissions have caused methane's atmospheric growth rate to slow. Our findings suggest that reduced fugitive fossil fuel emissions account for at least 10-21 teragrams per year (30-70 per cent) of the decrease in methane's global emissions, significantly contributing to methane's slowing atmospheric growth rate since the mid-1980s. 相似文献
19.
Meta-analysis of genome-wide association data and large-scale replication identifies additional susceptibility loci for type 2 diabetes 总被引:1,自引:0,他引:1
Zeggini E Scott LJ Saxena R Voight BF Marchini JL Hu T de Bakker PI Abecasis GR Almgren P Andersen G Ardlie K Boström KB Bergman RN Bonnycastle LL Borch-Johnsen K Burtt NP Chen H Chines PS Daly MJ Deodhar P Ding CJ Doney AS Duren WL Elliott KS Erdos MR Frayling TM Freathy RM Gianniny L Grallert H Grarup N Groves CJ Guiducci C Hansen T Herder C Hitman GA Hughes TE Isomaa B Jackson AU Jørgensen T Kong A Kubalanza K Kuruvilla FG Kuusisto J Langenberg C Lango H Lauritzen T Li Y Lindgren CM 《Nature genetics》2008,40(5):638-645
Genome-wide association (GWA) studies have identified multiple loci at which common variants modestly but reproducibly influence risk of type 2 diabetes (T2D). Established associations to common and rare variants explain only a small proportion of the heritability of T2D. As previously published analyses had limited power to identify variants with modest effects, we carried out meta-analysis of three T2D GWA scans comprising 10,128 individuals of European descent and approximately 2.2 million SNPs (directly genotyped and imputed), followed by replication testing in an independent sample with an effective sample size of up to 53,975. We detected at least six previously unknown loci with robust evidence for association, including the JAZF1 (P = 5.0 x 10(-14)), CDC123-CAMK1D (P = 1.2 x 10(-10)), TSPAN8-LGR5 (P = 1.1 x 10(-9)), THADA (P = 1.1 x 10(-9)), ADAMTS9 (P = 1.2 x 10(-8)) and NOTCH2 (P = 4.1 x 10(-8)) gene regions. Our results illustrate the value of large discovery and follow-up samples for gaining further insights into the inherited basis of T2D. 相似文献
20.
van Es MA van Vught PW Blauw HM Franke L Saris CG Van den Bosch L de Jong SW de Jong V Baas F van't Slot R Lemmens R Schelhaas HJ Birve A Sleegers K Van Broeckhoven C Schymick JC Traynor BJ Wokke JH Wijmenga C Robberecht W Andersen PM Veldink JH Ophoff RA van den Berg LH 《Nature genetics》2008,40(1):29-31
We identified a SNP in the DPP6 gene that is consistently strongly associated with susceptibility to amyotrophic lateral sclerosis (ALS) in different populations of European ancestry, with an overall P value of 5.04 x 10(-8) in 1,767 cases and 1,916 healthy controls and with an odds ratio of 1.30 (95% confidence interval (CI) of 1.18-1.43). Our finding is the first report of a genome-wide significant association with sporadic ALS and may be a target for future functional studies. 相似文献