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Search Results: 1 - 10 of 117835 matches for " T. Dalgaard "
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Genetic Variance in Uncoupling Protein 2 in Relation to Obesity, Type 2 Diabetes, and Related Metabolic Traits: Focus on the Functional ?866G>A Promoter Variant (rs659366)
Louise T. Dalgaard
Journal of Obesity , 2011, DOI: 10.1155/2011/340241
Abstract: Uncoupling proteins (UCPs) are mitochondrial proteins able to dissipate the proton gradient of the inner mitochondrial membrane when activated. This decreases ATP-generation through oxidation of fuels and may theoretically decrease energy expenditure leading to obesity. Evidence from Ucp(−/−) mice revealed a role of UCP2 in the pancreatic β-cell, because β-cells without UCP2 had increased glucose-stimulated insulin secretion. Thus, from being a candidate gene for obesity UCP2 became a valid candidate gene for type 2 diabetes mellitus. This prompted a series of studies of the human UCP2 and UCP3 genes with respect to obesity and diabetes. Of special interest was a promoter variant of UCP2 situated 866bp upstream of transcription initiation (−866G>A, rs659366). This variant changes promoter activity and has been associated with obesity and/or type 2 diabetes in several, although not all, studies. The aim of the current paper is to summarize current evidence of association of UCP2 genetic variation with obesity and type 2 diabetes, with focus on the −866G>A polymorphism.
Genetic Variance in Uncoupling Protein 2 in Relation to Obesity, Type 2 Diabetes, and Related Metabolic Traits: Focus on the Functional ?866G>A Promoter Variant (rs659366)
Louise T. Dalgaard
Journal of Obesity , 2011, DOI: 10.1155/2011/340241
Abstract: Uncoupling proteins (UCPs) are mitochondrial proteins able to dissipate the proton gradient of the inner mitochondrial membrane when activated. This decreases ATP-generation through oxidation of fuels and may theoretically decrease energy expenditure leading to obesity. Evidence from Ucp(?/?) mice revealed a role of UCP2 in the pancreatic β-cell, because β-cells without UCP2 had increased glucose-stimulated insulin secretion. Thus, from being a candidate gene for obesity UCP2 became a valid candidate gene for type 2 diabetes mellitus. This prompted a series of studies of the human UCP2 and UCP3 genes with respect to obesity and diabetes. Of special interest was a promoter variant of UCP2 situated 866bp upstream of transcription initiation (?866G>A, rs659366). This variant changes promoter activity and has been associated with obesity and/or type 2 diabetes in several, although not all, studies. The aim of the current paper is to summarize current evidence of association of UCP2 genetic variation with obesity and type 2 diabetes, with focus on the ?866G>A polymorphism. 1. Introduction Uncoupling protein 2 (UCP2) and uncoupling protein 3 (UCP3) belong to a large family of mitochondrial transmembrane carriers. UCP2 was identified in 1997 based on its homology to the brown fat uncoupling protein (UCP, then renamed UCP1) [1, 2]. Shortly thereafter, UCP3 was cloned also based on homology to UCP1 and UCP2 [3, 4]. Later, more distantly related proteins were identified and named UCP4 and UCP5 (BMCP1) [5–7]. The physiological role of UCP1 is well established; it is responsible for nonshivering thermogenesis in brown fat, in which it induces proton leak across the inner mitochondrial membrane [8, 9]. Now 14 years later, the physiological functions of UCP2 and UCP3 are still under debate, as is the role of genetic variation in these. The aim of this paper is to recapitulate the currently published literature on human genetic variation in the UCP2 genomic region concerning development of obesity, type 2 diabetes, and related metabolic disorders with focus on the ?866G>A promoter polymorphism (rs659366). 2. Physiological Functions of UCP2 and UCP3 UCP2 is ubiquitously expressed [1, 2] whereas UCP3 is found predominantly in skeletal muscle and brown adipose tissue [3, 4, 10], and their expression is both induced by fasting, and peroxisome proliferators as well as hyperglycemia, which indicates a role connected with the availability of fuel substrates [11–14]. However, the upregulation in response to thyroid hormone, cold, β3-adrenergic agonists, and high fat diets
Nitrous oxide emissions at the landscape scale: spatial and temporal variability
K. Schelde,P. Cellier,T. Bertolini,T. Dalgaard
Biogeosciences Discussions , 2011, DOI: 10.5194/bgd-8-11941-2011
Abstract: Nitrous oxide (N2O) emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape in Denmark, to investigate the main drivers of variations in N2O emissions, measured using static chambers. Measurements were done over a period of 20 months, and sampling was intensified during two weeks in spring 2009 when chambers were installed at ten locations or fields to cover different crops and topography and slurry was applied to three of the fields. N2O emissions during the spring 2009 period were relatively low, with maximum values below 20 ng N m 2 s 1. This applied to all land use types including winter grain crops, grassland, meadow, and wetland. Slurry application to wheat fields resulted in short-lived two-fold increases in emissions. The moderate N2O fluxes and their moderate response to slurry application were attributed to dry soil moisture conditions due to the absence of rain during the four previous weeks. Measured cumulated annual emissions from two arable fields that were both fertilized with mineral fertilizer and manure were large (17 kg N2O-N ha 1 yr 1 and 5.5 kg N2O-N ha 1 yr 1, respectively) during the previous year when soil water conditions were favourable for N2O production during the first month following fertilizer application, confirming the importance of the climatic regime on N2O fluxes.
Regional analysis of groundwater nitrate concentrations and trends in Denmark in regard to agricultural influence
B. Hansen,T. Dalgaard,L. Thorling,B. S?rensen
Biogeosciences Discussions , 2012, DOI: 10.5194/bgd-9-5321-2012
Abstract: The act of balancing between an intensive agriculture with a high potential for nitrate pollution and a~drinking water supply almost entirely based on groundwater is a challenge faced by Denmark and similar regions around the globe. Since the 1980s, regulations implemented by Danish farmers have succeeded in optimizing the N (nitrogen) management at farm level. As a result, the upward agricultural N surplus trend has been reversed, and the N surplus has reduced by 30–55 % from 1980 to 2007 depending on region. The reduction in the N surplus served to reduce the losses of N from agriculture, with documented positive effects on nature and the environment in Denmark. In groundwater, the upward trend in nitrate concentration was reversed around 1980, and a larger number of downward nitrate trends were seen in the youngest groundwater compared with the oldest groundwater. However, on average, approximately 48 % of the oxic monitored groundwater has nitrate concentrations above the groundwater and drinking water standards of 50 mg l 1. Furthermore, trend analyses show that 33 % of all the monitored groundwater has upward nitrate trends, while only 18 % of the youngest groundwater has upward nitrate trends according to data sampled from 1988–2009. A regional analysis shows a correlation between a high level of N surplus in agriculture, high concentrations of nitrate in groundwater and the largest number of downward nitrate trends in groundwater in the livestock-dense northern and western parts of Denmark compared with the south-eastern regions with lower livestock densities. These results indicate that the livestock farms dominating in northern and western parts of Denmark have achieved the largest reductions in N surpluses. Groundwater recharge age determinations allow comparison of long-term changes in N surplus in agriculture with changes in oxic groundwater quality. The presented data analysis is based on groundwater recharged from 1952–2003, but sampled from 1988–2009. Repetition of the nitrate trend analyses at five-year intervals using dating of the groundwater recharged in the coming years and a longer time series of the nitrate analyses can reveal the evolution in nitrate leaching from Danish agriculture during the past 10 yr. Similar analyses can be carried out to compare with other regions internationally.
Farm nitrogen balances in six European agricultural landscapes – a method for farming system assessment, emission hotspot identification, and mitigation measure evaluation
T. Dalgaard,J. F. Bienkowski,A. Bleeker,J. L. Drouet
Biogeosciences Discussions , 2012, DOI: 10.5194/bgd-9-8859-2012
Abstract: Six agricultural landscapes in Poland (PL), the Netherlands (NL), France (FR), Italy (IT), Scotland (UK) and Denmark (DK) were studied, and a common method was developed for undertaking farm inventories and the derivation of farm nitrogen (N) balances and N surplus from the in total 222 farms and 11 440 ha of farmland. In all landscapes, a large variation in the farm N surplus was found, and thereby a large potential for reductions. The highest average N surpluses were found in the most livestock-intensive landscapes of IT, FR, and NL; on average 202 ± 28, 179 ± 63 and 178 ± 20 kg N ha 1yr 1, respectively. However, all landscapes showed hotspots, especially from livestock farms, including a special UK case with landless large-scale poultry farming. So, whereas the average N surplus from the land-based UK farms dominated by extensive sheep grazing was only 31 ± 10 kg N ha 1yr 1, the landscape average was similar to those of PL and DK (122 ± 20 and 146 ± 55 kg N ha 1yr 1, respectively) when landless poultry were included. However, the challenge remains how to account for indirect N surpluses and emissions from such farms with a large export of manure out of the landscape. We conclude that farm N balances are a useful indicator for N losses and the potential for improving N management. Significant correlations to N surplus were found, both with ammonia air concentrations and nitrate levels in soils and groundwater, measured during the landscape data collection campaign from 2007–2009. This indicates that farm N surpluses may be used as an independent dataset for validation of measured and modelled N emissions in agricultural landscapes. However, no significant correlation was found to N measured in surface waters, probably because of the short time horizon of the study. A case study of the development in N surplus from the landscape in DK from 1998–2008 showed a 22 % reduction, related to statistically significant effects (p < 0.01) of measures targeted at reducing N emissions from livestock farms. Based on the large differences between the average and the most modern and N-efficient farms, it was concluded that N-surplus reductions of 25–50 % as compared to the present level were realistic in all landscapes. The implemented N-surplus method was thus effective at comparing and synthesizing results on farm N emissions and the potentials of mitigation options, and is recommended for use in combination with other methods for the assessment of landscape N emissions and farm N efficiency, including more detailed N sink and N source hotspot mapping, measurements
Scholarly Collections on the Web: Media Reconfigurations at Play
Rune Dalgaard
Human IT: Tidskrift f?r Studier av IT ur ett Humanvetenskapligt Perspektiv , 2004,
Abstract: With the Internet a new medium has become available for communicating scholarly texts. This article focuses on the World Wide Web (the Web) as a global, hypertextual archive for scholarly texts and its significance in reconfiguring the corpus of scholarly texts. The first part addresses the Web in light of hypertext theory and a media theoretic perspective, concentrating on its roots in issues related to the flood of information and its qualities as a medium. The second part will zoom in on the actual use of the Web as a publication and archival medium for scholars, with a focus on two different scholarly archives. The article concludes with some general reflections on the Web as an archive of archives based on the concepts of network and complexity.
Spatial and temporal variability of nitrous oxide emissions in a mixed farming landscape of Denmark
K. Schelde, P. Cellier, T. Bertolini, T. Dalgaard, T. Weidinger, M. R. Theobald,J. E. Olesen
Biogeosciences (BG) & Discussions (BGD) , 2012,
Abstract: Nitrous oxide (N2O) emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape in Denmark, to investigate the main drivers of variations in N2O emissions, measured using static chambers. Measurements were made over a period of 20 months, and sampling was intensified during two weeks in spring 2009 when chambers were installed at ten locations or fields to cover different crops and topography and slurry was applied to three of the fields. N2O emissions during spring 2009 were relatively low, with maximum values below 20 ng N m 2 s 1. This applied to all land use types including winter grain crops, grasslands, meadows, and wetlands. Slurry application to wheat fields resulted in short-lived two-fold increases in emissions. The moderate N2O fluxes and their moderate response to slurry application were attributed to dry soil conditions due to the absence of rain during the four previous weeks. Cumulative annual emissions from two arable fields that were both fertilized with mineral fertilizer and manure were large (17 kg N2O-N ha 1 yr 1 and 5.5 kg N2O-N ha 1 yr 1) during the previous year when soil water conditions were favourable for N2O production during the first month following fertilizer application. Our findings confirm the importance of weather conditions as well as nitrogen management on N2O fluxes.
Regional analysis of groundwater nitrate concentrations and trends in Denmark in regard to agricultural influence
B. Hansen, T. Dalgaard, L. Thorling, B. S rensen,M. Erlandsen
Biogeosciences (BG) & Discussions (BGD) , 2012,
Abstract: The act of balancing between an intensive agriculture with a high potential for nitrate pollution and a drinking water supply almost entirely based on groundwater is a challenge faced by Denmark and similar regions around the globe. Since the 1980s, regulations implemented by Danish farmers have succeeded in optimizing the N (nitrogen) management at farm level. As a result, the upward agricultural N surplus trend has been reversed, and the N surplus has reduced by 30–55% from 1980 to 2007 depending on region. The reduction in the N surplus served to reduce the losses of N from agriculture, with documented positive effects on nature and the environment in Denmark. In groundwater, the upward trend in nitrate concentrations was reversed around 1980, and a larger number of downward nitrate trends were seen in the youngest groundwater compared with the oldest groundwater. However, on average, approximately 48% of the oxic monitored groundwater has nitrate concentrations above the groundwater and drinking water standards of 50 mg l 1. Furthermore, trend analyses show that 33% of all the monitored groundwater has upward nitrate trends, while only 18% of the youngest groundwater has upward nitrate trends according to data sampled from 1988–2009. A regional analysis shows a correlation between a high level of N surplus in agriculture, high concentrations of nitrate in groundwater and the largest number of downward nitrate trends in groundwater in the livestock-dense northern and western parts of Denmark compared with the southeastern regions with lower livestock densities. These results indicate that the livestock farms dominating in northern and western parts of Denmark have achieved the largest reductions in N surpluses. Groundwater recharge age determinations allow comparison of long-term changes in N surplus in agriculture with changes in oxic groundwater quality. The presented data analysis is based on groundwater recharged from 1952–2003, but sampled from 1988–2009. Repetition of the nitrate trend analyses at five-year intervals using dating of the groundwater recharged in the coming years and a longer time series of the nitrate analyses can reveal the evolution in nitrate leaching from Danish agriculture during the past 10 yr. Similar analyses can be carried out to compare with other regions internationally.
Management, regulation and environmental impacts of nitrogen fertilization in Northwestern Europe under the Nitrates Directive; a benchmark study
H. J. M. van Grinsven,H. F. M. ten Berge,T. Dalgaard,B. Fraters
Biogeosciences Discussions , 2012, DOI: 10.5194/bgd-9-7353-2012
Abstract: Implementation of the Nitrates Directive (NiD) and its environmental impacts were compared for member states in the Northwest of the European Union (Ireland, UK, Denmark, The Netherlands, Belgium, Northern France and Germany). The main sources of data were national reports for the third reporting period for the NiD (2004–2007) and results of the MITERRA-EUROPE model. Implementation of the NiD in the considered member states is fairly comparable regarding restrictions for where and when to apply fertilizer and manure, but very different regarding application limits for N fertilization. Issues of concern and improvement of the implementation of the NiD are accounting for the fertilizer value of nitrogen in manure, and relating application limits for total nitrogen (N) to potential crop yield and N removal. The most significant environmental effect of the implementation of the NiD since 1995 is a major contribution to the decrease of the soil N balance (N surplus), particularly in Belgium, Denmark, Ireland, The Netherlands and the UK. This decrease is accompanied by a modest decrease of nitrate concentrations since 2000 in fresh surface waters in most countries. This decrease is less prominent for groundwater in view of delayed response of nitrate in deep aquifers. In spite of improved fertilization practices, the southeast of The Netherlands, the Flemish Region and Brittany remain to be regions of major concern in view of a combination of a high nitrogen surplus, high leaching fractions to groundwater and tenacious exceedance of the water quality standards. On average the gross N balance in 2008 for the seven member states in EUROSTAT and in national reports was about 20 kg N ha 1 lower than by MITERRA. The major cause is higher estimates of N removal in national reports which can amount to more than 50kg N ha 1. Differences between procedures in member states to assess nitrogen balances and water quality and a lack of cross boundary policy evaluations are handicaps when benchmarking the effectiveness of the NiD. This provides a challenge for the European Commission and its member states as the NiD remains an important piece of legislation for protecting drinking water quality in regions with many private or small public production facilities and controlling aquatic eutrophication from agricultural sources.
Spatial distribution of soils determines export of nitrogen and dissolved organic carbon from an intensively managed agricultural landscape
T. Wohlfart, J.-F. Exbrayat, K. Schelde, B. Christen, T. Dalgaard, H.-G. Frede,L. Breuer
Biogeosciences (BG) & Discussions (BGD) , 2012,
Abstract: The surrounding landscape of a stream has crucial impacts on the aquatic environment. This study pictures the hydro-biogeochemical situation of the Tyreb kken creek catchment in central Jutland, Denmark. The intensively managed agricultural landscape is dominated by rotational croplands. The small catchment mainly consist of sandy soil types besides organic soils along the streams. The aim of the study was to characterise the relative influence of soil type and land use on stream water quality. Nine snapshot sampling campaigns were undertaken during the growing season of 2009. Total dissolved nitrogen (TDN), nitrate (NO3 ), ammonium nitrogen and dissolved organic carbon (DOC) concentrations were measured, and dissolved organic nitrogen (DON) was calculated for each grabbed sample. Electrical conductivity, pH and flow velocity were measured during sampling. Statistical analyses showed significant differences between the northern, southern and converged stream parts, especially for NO3 concentrations with average values between 1.4 mg N l 1 and 9.6 mg N l 1. Furthermore, throughout the sampling period DON concentrations increased to 2.8 mg N l 1 in the northern stream contributing up to 81% to TDN. Multiple-linear regression analyses performed between chemical data and landscape characteristics showed a significant negative influence of organic soils on instream N concentrations and corresponding losses in spite of their overall minor share of the agricultural land (12.9%). On the other hand, organic soil frequency was positively correlated to the corresponding DOC concentrations. Croplands also had a significant influence but with weaker correlations. For our case study we conclude that the fractions of coarse textured and organic soils have a major influence on N and DOC export in this intensively used landscape. Meanwhile, the contribution of DON to the total N losses was substantial.
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