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61.
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63.
Per Alm Lena-Maria Lundberg John Wharton Julia M. Polak 《The Histochemical journal》1988,20(8):414-426
Summary The extrinsic innervation of the guinea pig uterus was studied by immunohistochemical, ultrastructural and enzyme histochemical methods.The extrinsic innervation was organized in two major ways. One consisted of nerve trunks and non-varicose nerve fibres running in the suspensory ligament, and the other of a plexus of varicose nerve fibres surrounding vessels, and non-vessel-related non-varicose nerve fibres in the mesouterus. The use of different neuronal and Schwann cell markers showed that the extrinsic innervation was predominantly adrenergic and contained only few peptidergic nerves. Acetylcholinesterase-positive (cholinergic) nerves were only found around the uterine artery.In late pregnancy, the extrinsic nerves of the mesouterus adjacent to foetus-containing uterine horns underwent pronounced degenerative changes comprising both Schwann cell and axonal structures. In comparison, no changes were found in extrinsic nerves of mesouteri adjacent to non-foetus-bearing uterine horns or in extrinsic nerves in the suspensory ligaments. Further, chemical sympathectomy produced axonal degeneration but no changes in the Schwann cells.In conclusion, the pregnancy-induced nerve degeneration is of a very special type different from that following chemical sympathectomy and represents a local phenomenon related to the conceptus. Hypothetically, this could be of importance for counteracting disturbances in placental blood flow. 相似文献
64.
Eszter Nyúl Mónika Kuzma Mátyás Mayer Sándor Lakatos Attila Almási 《Free radical research》2013,47(9):1040-1051
AbstractFenton-reaction initiated in vitro oxidation and in vivo oxidative biotransformation of salicylic acid was investigated by HPLC-UV-Vis method. By means of the developed high performance liquid chromatography (HPLC) method salicylic acid, catechol, and all the possible monohydroxylated derivatives of salicylic acid can be separated. Fenton oxidations were performed in acidic medium (pH 3.0) with two reagent molar ratios: (1) salicylic acid: iron: hydrogen peroxide 1:3:1 and (2) 1:0.3:1. The incubation samples were analysed at different time points of the reactions. The biological effect of elevated reactive oxygen species concentration on the intestinal metabolism of salicylic acid was investigated by an experimental diabetic rat model. HPLC-MS analysis of the in vitro samples revealed presence of 2,3- and 2,5-dihydroxybenzoic acids. The results give evidence for nonenzyme catalysed intestinal hydroxylation of xenobiotics. 相似文献
65.
Bending of apricot tree branches under the weight of axillary growth: test of a mechanical model with experimental data 总被引:3,自引:0,他引:3
Stem orientation is an important factor for fruit tree growth and branching habit since it influences fruit production as well as training practices. A mechanical model of the bending of a stem under axillary load was written and evaluated using experimental data on apricot trees (Prunus armeniaca L.). A set of 15 1-year-old stems of various shapes was observed during the early stage of the growing season when radial growth is still negligible and the loading of the stem increases considerably. The structural modulus of elasticity (MOE) of the stems was estimated through in situ bending tests assuming homogeneous material behaviour. The effect of viscoelasticity was observed through creep tests performed on similar stems during winter. Inputs of the model are initial shape, initial diameter, and final load, defined at various positions along the stem. The final shape was simulated based on different mechanical assumptions, and compared to observations. Assuming small deflections resulted in an underestimate of the mean slope variation of 48%, accounting for large displacements reduced this underestimate to 29% and accounting for viscoelasticity reduced it further to 14%. An adjustment of the structural MOE to fit the final shape led to an excellent fit of the data in most cases, the residual errors for some axes being attributed to material heterogeneity. The use of biomechanical models to predict the shape of fruit trees based on growth parameters, provided adequate assumptions are made, is discussed. 相似文献
66.
Yves T. Prairie Jukka Alm Jake Beaulieu Nathan Barros Tom Battin Jonathan Cole Paul del Giorgio Tonya DelSontro Frédéric Guérin Atle Harby John Harrison Sara Mercier-Blais Dominique Serça Sebastian Sobek Dominic Vachon 《Ecosystems》2018,21(5):1058-1071
Freshwater reservoirs are a known source of greenhouse gas (GHG) to the atmosphere, but their quantitative significance is still only loosely constrained. Although part of this uncertainty can be attributed to the difficulties in measuring highly variable fluxes, it is also the result of a lack of a clear accounting methodology, particularly about what constitutes new emissions and potential new sinks. In this paper, we review the main processes involved in the generation of GHG in reservoir systems and propose a simple approach to quantify the reservoir GHG footprint in terms of the net changes in GHG fluxes to the atmosphere induced by damming, that is, ‘what the atmosphere sees.’ The approach takes into account the pre-impoundment GHG balance of the landscape, the temporal evolution of reservoir GHG emission profile as well as the natural emissions that are displaced to or away from the reservoir site resulting from hydrological and other changes. It also clarifies the portion of the reservoir carbon burial that can potentially be considered an offset to GHG emissions. 相似文献
67.
S. Saarnio Jukka Alm Jouko Silvola Annalea Lohila Hannu Nykänen Pertti J. Martikainen 《Oecologia》1997,110(3):414-422
Temporal and spatial variation in CH4 emissions was studied at hummock, Eriophorum lawn, flark and Carex lawn microsites in an oligotrophic pine fen over the growing season using a static chamber method, and CH4 production and oxidation potentials in peat profiles from hummock and flark were determined in laboratory incubation experiments.
Emissions were lowest in the hummocks, and decreased with increasing hummock height, while in the lawns and flarks they increased
with increasing sedge cover. Statistical response functions with water table and peat temperature as independent variables
were calculated in order to reconstruct seasonal CH4 emissions by reference to the time series for peat temperature and water table specific to each microsite type. Mean CH4 emissions in the whole area in the snow-free period of 1993, weighted in terms of the proportions of the microsites, were
1.7 mol CH4 m–2. Potential CH4 production and oxidation rates were very low in the hummocks rising above the groundwater table, but were relatively similar
when expressed per dry weight of peat both in the hummocks and flarks below the water table. The CH4 production potential increased in autumn at both microsites and CH4 oxidation potential seemed to decrease. The decrease in temperature in autumn certainly reduced in situ decomposition processes,
possibly leaving unused substrates in the peat, which would explain the increase in CH4 production potential.
Received: 16 August 1996 / Accepted: 30 November 1996 相似文献
68.
A data base was generated for quantifying effects of thermal time (degree-days) on the appearance of new leaves, the expansion of such leaves to maximum area, their death, the appearance of new internodes below the node associated with such leaves, and the extension of these internodes to maximum length. The data base for a list of crop (agronomic and horticultural), weed, and native Tallgrass Prairie plants has been summarized, with equations for the above events as a function of degree days, with appropriate base temperatures and maximum cut-off temperatures, in a Java applet which is available at a website with the URL . Associated graphical plots such as shown in this paper are also given. Branching behavior was accounted for. These events predict the effect of thermal time on leaf age and its height in the plant canopy, both important factors needed for upscaling functions for leaf behavior to those for behavior of the plant canopy. The data base is evolving to include coefficients for other species. Coefficients are used to predict the leaf area index of the canopy, which is important for predicting evapotranspiration from the crop and the protection of the soil from erosion. 相似文献
69.
Joana Alves Dias Sophie Hellstrand Ulrika Ericson Bo Gullberg Jan Nilsson Ragnar Alm 《Biomarkers》2016,21(6):562-571
Context: Large epidemiological studies often collect non-fasting samples, although the reliability of biomarkers may be uncertain.Objective: To explore the reliability and reproducibility of a single measurement of selected biomarkers in a sub-sample of the Malmö Diet and Cancer cohort.Methods: We estimated single- and average-measures intraclass correlation coefficients (ICC) for oxidized (ox)-LDL, interleukin (IL)-1β, IL-6, IL-8 and TNF-α.Results: Single-measures ICC in non-fasting samples of ox-LDL, IL-1β, IL-6, IL-8 and TNF-α were the following: 0.85, 0.71, 0.61, 0.78 and 0.66 for men, and 0.67, 0.81, 0.87, 0.69 and 0.81 for women. Biomarkers at non-fasting and fasting samples were highly correlated (all r?>?0.80).Conclusions: The observed ICC suggest that most of the examined biomarkers (non-fasting blood) would allow meaningful analysis in epidemiological studies. 相似文献
70.
Topoisomerase II is nonfunctional in polyamine-depleted cells. 总被引:2,自引:0,他引:2
The polyamines-putrescine, spermidine, and spermine-are essential for normal cell proliferation. Polyamine depletion affects DNA structure and synthesis. Topoisomerase II (topo II) is also necessary for normal cell proliferation, and it has been shown in vitro that polyamines may affect topo II activity. In order to investigate the effect of polyamine depletion on topo II activity, we treated Chinese hamster ovary cells with either alpha-difluoromethylornithine (DFMO) or 4-amidinoindan-1-one-2'-amidinohydrazone (CGP 48664), which are polyamine biosynthesis inhibitors. Treatment with the topo II inhibitor etoposide results in DNA strand breaks only if there is active topo II in the cells. By quantitating DNA strand breaks after etoposide treatment using single cell gel electrophoresis, we were able to estimate intracellular topo II activity. We also quantitated topo II activity in crude nuclear extracts from control and polyamine biosynthesis inhibitor-treated cells. Using single cell gel electrophoresis, we noted a clear decrease in the function of topo II in polyamine biosynthesis inhibitor-treated cells, as compared with untreated control cells. However, the topo II activity in crude nuclear extracts did not differ significantly in control versus polyamine biosynthesis inhibitor-treated cells. Taken together, these results indicate that although the function of topo II in polyamine-depleted cells was impaired, topo II remained functional in an in vitro assay. Using the single cell gel electrophoresis assay, we also found that spermine depletion itself caused DNA strand breaks. 相似文献