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- Isaksson, B, et al.
(författare)
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Obstructive jaundice results in increased liver expression of uncoupling protein 2 and intact skeletal muscle glucose metabolism in the rat
- 2002
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 1502-7708 .- 0036-5521. ; 37:1, s. 104-111
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Tidskriftsartikel (refereegranskat)abstract
- Background: A majority of patients with pancreatic cancer have obstructive jaundice and diabetes with skeletal muscle insulin resistance. Surgery for these patients is associated with significant morbidity. Uncoupling protein 2 (UCP2) has been proposed to regulate energy expenditure and promote liver vulnerability. The effects of obstructive jaundice on muscle glucose metabolism and expression of UCP2 in liver and muscle are unknown. Methods: Rats were operated with bile duct ligation (BDL). After 7 days, UCP2 mRNA levels were determined in liver and muscle. Simultaneously, insulin-stimulated glucose transport and glycogen synthesis in skeletal muscle were analyzed in vitro. Results: The jaundiced rats lost more weight than pair-fed controls. UCP2 mRNA levels were increased 5-fold in liver but not in muscle in jaundiced rats compared to pair-fed controls. The jaundiced rats were hypoglycemic and hypoinsulinemic but demonstrated intact or enhanced insulin action on skeletal muscle glucose transport and glycogen synthesis in vitro. Muscle glycogen content was increased in the jaundiced rats. Conclusions: Experimental obstructive jaundice in the rat is associated with increased liver expression of UCP2. rapid weight loss, and intact insulin action on skeletal Muscle glucose metabolism. Obstructive jaundice. by upregulated liver UCP2. may contribute to the cachexia and high surgical morbidity observed in these patients, but not to skeletal muscle insulin resistance in pancreatic cancer patients.
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- Isaksson, E, et al.
(författare)
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Ice cores from Svalbard :useful archives of past climate and pollution history.
- 2003
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Ingår i: Physics and chemistry of the earth. Part A. - : Elsevier BV. - 1464-1895 .- 1873-4642 .- 1474-7065. ; 28:28-32, s. 1217-1228
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Tidskriftsartikel (refereegranskat)abstract
- Ice cores from the relatively low-lying ice caps in Svalbard have not been widely exploited in climatic and environmental studies due to uncertainties about the effect of melt water percolation. However, results from two recent Svalbard ice cores, at Lomonosovfonna (1250 m asl) and Austfonna (750 m asl), have shown that with careful site selection, high-resolution sampling and multiple chemical analyses, it is possible to recover ice cores with partly preserved annual signals. These cores are estimated to cover at least the past 600 years and have been dated using a combination of known reference horizons and glacial modeling. The δ18O data from both Lomonosovfonna and Austfonna ice cores suggest that the 20th century was the warmest during the past 600 years. A comparison of the ice core and sea ice records from this period suggests that sea ice extent and Austfonna δ18O are linked over the past 400 years. This may reflect the position of the storm tracks and their direct influence on the relatively low altitude Austfonna. Lomonosovfonna may be less sensitive to such changes and primarily record atmospheric changes due to its higher elevation. The anthropogenic influence on Svalbard environment is illustrated by increased levels of non-sea-salt sulphate, nitrate, acidity, fly-ash and organic contaminants particularly during the second half of 1900s. Decreased concentrations of some components in recent decades most likely reflect emission and use restrictions. However, some current-use organic pesticide compounds show growing concentrations in near surface layers.
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- Pohjola, V, et al.
(författare)
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Effect of periodic melting on geochemical and isotopic signals in an ice core from Lomonosovfonna, Svalbard
- 2002
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Ingår i: J.Geophys.Res.. ; 107:D4, s. ACL 1-14
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Tidskriftsartikel (refereegranskat)abstract
- In this work we examine the quality of the atmospherically deposited signals in an ice core taken from a periodically melting ice field, Lomonosovfonna on central Spitsbergen, Svalbard. The aim is to investigate how much the atmospheric deposited signals in the stratigraphy of ice pack are changed by periodic melting of the ice. To determine the impact of this melting on the stratigraphy found in the ice core, we use three diagnostics: 1) Association between peak values in the ice chemical and isotopic record and ice facies type; 2) Number of “annual” cycles in these records compared with independently-determined number of years represented in the ice core; 3) Statistical comparison between the isotopic record in the ice core and the isotope records from coastal stations from the same region. We find that during warm summers as much as 50% of the annual accumulation may melt and percolate into the firn, and in a median year this decreases to ca. 25 %. As a consequence of percolation the most mobile acids show upto 50 % higher concentrations in bubble poor ice facies compared with facies that are less affected by melt. Most of the other chemical species are less affected than the strong acids, and the stable water isotopes show little evidence of mobility Annual, or bi-annual cycles are detected in most parameters, and the water isotope record has a comparable statistical distribution to isotopic records from coastal stations. We conclude that ice cores from sites like Lomonosovfonna preserve an useful environmental record despite melt events and percolation, where most parameters displays an annual, or in poor cases a bi-annual atmospheric signal.
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- Pohjola, V, et al.
(författare)
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Reconstruction of three centuries of annual accumulation rates based on the record of stable isotopes of water from Lomonosovfonna, Svalbard
- 2002
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Ingår i: Annals of glaciology. ; 35, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- We use the upper 81 m of the record of stable isotopes of water from a 122 m long ice core from Lomonosovfonna, central Spitsbergen, to construct an ice core chronology and the annual accumulation rates over the ice field. The isotope cycles are counted in the ice core record using a model that neglects short wavelength and low amplitude cycles. We find approximately the same number of ä18O cycles as years between known reference horizons, and assume these cycles represent annual cycles. Testing the validity of this assumption using cycles in äD shows that both records give similar numbers of cycles. Using the ä18O chronology, and de-compressing the accumulation records using the Nye flow model, we calculate the annual accumulation for the ice core site back to 1715 AD. We find that the average accumulation rate from 1715 to 1950 o was on average 0.30 m w.e. Accumulation rates increased ca. 25% during the later part of the 20th century to an average of 0.41 m w.e. for the period 1950 – 1997. The accumulation rates show highly significant 2.1 and 21 year periodicities, which gives credibility to our time scale.
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