| 1. |
- Sahlin, Kent, et al.
(författare)
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No evidence of an intracellular lactate shuttle in rat skeletal muscle.
- 2002
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Ingår i: Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 541:Pt 2, s. 569-74
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Tidskriftsartikel (refereegranskat)abstract
- The concerted view is that cytosolic pyruvate is transferred into mitochondria and after oxidative decarboxylation further metabolized in the tricarboxylic acid cycle. Recently this view has been challenged. Based on experimental evidence from rat skeletal muscle it has been concluded that mitochondria predominantly oxidize lactate in vivo and that this constitutes part of an 'intracellular lactate shuttle'. This view appears to be gaining acceptance in the scientific community and due to its conceptual importance, confirmation by independent experiments is required. We have repeated the experiments in mitochondria isolated from rat soleus muscle. Contrary to the previously published findings we cannot find any mitochondrial respiration with lactate. Analysis of lactate dehydrogenase (LDH) by spectrophotometry demonstrated that the activity in the mitochondrial fraction was only 0.7 % of total activity. However, even when external LDH was added to mitochondria, there were no signs of respiration with lactate. In the presence of conditions where lactate is converted to pyruvate (external additions of both LDH and NAD(+)), mitochondrial oxygen consumption increased. Furthermore, we provide theoretical evidence that direct mitochondrial lactate oxidation is energetically unlikely. Based on the present data we conclude that direct mitochondrial lactate oxidation does not occur in skeletal muscle. The presence of an 'intracellular lactate shuttle' can therefore be questioned.
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| 2. |
- Cotgreave, Ian A, et al.
(författare)
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Differentiation-specific alterations to glutathione synthesis in and hormonally stimulated release from human skeletal muscle cells.
- 2002
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Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 16:3, s. 435-7
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Tidskriftsartikel (refereegranskat)abstract
- Muscle atrophy and cachexia are associated with many human diseases. These catabolic states are often associated with the loss of glutathione (GSH), which is thought to contribute to the induction of oxidative stress within the muscle. Glutathione synthesis and secretary characteristics were studied in human skeletal muscle myoblasts and myotube-like cells derived from the myoblasts by growth factor restriction. Differentiation was associated with a shift in the sulfur amino acid precursor specificity for synthesis of GSH from cystine to cysteine, as well as loss in ability to use extracellular glutathione and activation of methionine use. The thiol drug N-acetylcysteine was also shown to be an effective precursor irrespective of the state of differentiation. Additionally, myoblasts and myotube cultures were shown to secrete GSH continually, but only the differentiated cells responded to stress hormones such as glucagon, vasopressin, and phenylephrine, by increased secretion of the tripeptide. The data suggest that the skeletal muscle cells may provide an important hormonally regulated extra-hepatic source of systemic GSH and also shed light on the mechanisms of accelerated turnover of GSH operating during strenuous muscle activity and trauma. The data may also provide biochemical rationales for the nutritional and/or pharmacological manipulation of GSH with sulfur amino acid precursors during the treatment of muscle-specific oxidative stress and atrophy.
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| 3. |
- Tonkonogi, Michail, et al.
(författare)
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Mitochondrial function and antioxidative defence in human muscle : effects of endurance training and oxidative stress.
- 2000
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Ingår i: Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 528 Pt 2, s. 379-88
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Tidskriftsartikel (refereegranskat)abstract
- The influence of endurance training on oxidative phosphorylation and the susceptibility of mitochondrial oxidative function to reactive oxygen species (ROS) was investigated in skeletal muscle of four men and four women. Mitochondria were isolated from muscle biopsies taken before and after 6 weeks of endurance training. Mitochondrial respiration was measured before and after exposure of mitochondria to exogenous ROS (H2O2 + FeCl2). Endurance training increased peak pulmonary O2 uptake (VO2,peak) by 24 % and maximal ADP-stimulated mitochondrial oxygen consumption (state 3) by 40% (P<0.05). Respiration in the absence of ADP (state 4), the respiratory control ratio (RCR = state 3/state 4) and the ratio between added ADP and consumed oxygen (P/O) remained unchanged by the training programme. Exposure to ROS reduced state 3 respiration but the effect was not significantly different between pre- and post-training samples. State 4 oxygen consumption increased after exposure to ROS both before (+189 %, P< 0.05) and after training (+243 %, P<0.05) and the effect was significantly higher after training (P<0.05, pre- vs. post-training). The augmented state 4 respiration could in part be attenuated by atractyloside, which indicates that ADP/ATP translocase was affected by ROS. The P/O ratio in ROS-treated mitochondria was significantly lower (P<0.05) compared to control conditions, both before (-18.6+/-2.2 %) and after training (-18.5+/-1.1%). Muscle activities of superoxide dismutase (mitochondrial and cytosolic), glutathione peroxidase and muscle glutathione status were unaffected by training. There was a positive correlation between muscle superoxide dismutase activity and age (r = 0.75; P<0.05; range of age 20-37 years), which may reflect an adaptation to increased generation of ROS in senescent muscle. The muscle glutathione pool was more reduced in subjects with high activity of glutathione peroxidase (r = 0.81; P<0.05). The influence of short-term training on mitochondrial oxygen consumption has for the first time been investigated in human skeletal muscle. The results showed that maximal mitochondrial oxidative power is increased after endurance training but that the efficiency of energy transfer (P/O ratio) remained unchanged. Antioxidative defence was unchanged after training when expressed relative to muscle weight. Although this corresponds to a reduced antioxidant protection per individual mitochondrion, the sensitivity of aerobic energy transfer to ROS was unchanged. However, the augmented ROS-induced non-coupled respiration after training indicates an increased susceptibility of mitochondrial membrane proton conductance to oxidative stress.
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| 4. |
- Brännäs, Kurt, et al.
(författare)
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An Integer-Valued Time Series Model for Hotels that Accounts for Constrained Capacity
- 2004
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Ingår i: Studies in Nonlinear Dynamics and Econometrics. - : Walter de Gruyter GmbH. - 1558-3708 .- 1081-1826. ; 8:4, s. Article 6-
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Tidskriftsartikel (refereegranskat)abstract
- Many service industry firms strive hard to fill free capacity in order to cover their costs for a fixed capital stock. This paper presents a time series model where the capacity constraint is an integral part. The integer-valued autoregressive model builds on a simple idea of how daily time series arise for hotels and other similar establishments. Measures that follow naturally from the time series model are the occupancy probability and the duration of stay for the visitor. Empirically, we study the effects of price changes and a large festival, on these measures.
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| 5. |
- Lundgren, Berit, 1951-
(författare)
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Att som vuxen bli litterat på sitt andraspråk
- 2002. - 1
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Ingår i: Forskning i nordiske sprog som andet- og fremmedsprog. - Reykjavík : Háskóli Íslands. - 9979545402 ; , s. 295-314
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Lundgren, Berit, 1951-
(författare)
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"Jag har tio barn så jag behöver inte bekymra mig om min ålderdom" : om skolans möjligheter att skapa förståelse
- 2004. - 1
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Ingår i: Andra nationella konferensen i svenska med didaktisk inriktning. - Göteborg : Göteborgs universitet. - 9197472212 ; , s. 123-139
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Skolan har ett stort och viktigt ansvar för att utveckla kunskaper i det svenska språket för människor som kommer till Sverige från andra länder. I kapitlet beskrivs, utifrån ett sociokulturellt perspektiv, hur några kvinnor som är analfabeter lär sig det svenska språket samt lär sig läsa och skriva på svenska inom svenskundervisning för invandrare. Studien som har sitt ursprung i avhandlingen Skolan i livet - Livet i skolan visar att kommunikation vanligtvis bygger på I-R-U mönster men att kollaborativa samtal förekommer. Det som också framkommer är att deltagarnas erfrenheter inte tas tillvara i undersvisningssituationer i någon större utsträckning. Det medför i sin tur att deltagarna känner sig okunniga.
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| 7. |
- Nilsson, Peter
(författare)
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Empathy and emotions : on the notion of empathy as emotional sharing
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The topic of this study is a notion of empathy that is common in philosophy and in the behavioral sciences. It is here referred to as ‘the notion of empathy as emotional sharing’, and it is characterized in terms of three ideas. If a person, S, has empathy with respect to an emotion of another person, O, then (i) S experiences an emotion that is similar to an emotion that O is currently having, (ii) S’s emotion is caused, in a particular way, by the state of O or by S’s entertaining an idea of the state or situation of O, and (iii) S experiences this emotion in a way that does not entail that S is in the corresponding emotional state. The aim of the study is to clarify this notion of empathy by clarifying these three ideas and by tracing the history of their development in philosophy.The study consists of two parts. Part one contains a short and selective account of the history in Western philosophy of the notion of empathy as emotional sharing. In chapter 2 Spinoza’s theory of imitation of affects and Hume’s theory of sympathy are presented. It is argued that these theories only exemplify the second idea characteristic of the notion of empathy as emotional sharing. Chapter 3 contains presentations of Adam Smith’s theory of sympathy, and Schopenhauer’s theory of compassion. These theories are shown to exemplify the second and the third idea. In chapter 4 there are presentations of Edith Stein’s description of Einfühlung, and Max Scheler’s account of empathy and fellow-feeling. It is shown that these accounts contain explicit specifications of the third idea, and it is argued that they also exemplify the second idea.In part two, the three ideas are further clarified and the notion of empathy as emotional sharing is defined. Chapter 5 contains a discussion of the main contemporary philosophical analyses of empathy. Three different views are distinguished: one that construes empathetic emotions as emotional states, one that construes them as imagined emotions, and one that construes them as off-line emotions. The first two views are criticized and rejected. The third is accepted and further developed in chapter 6, which contains a general analysis of the emotions. A distinction is made between two ways of experiencing an emotion, and it is argued that it is possible to have the affective experience characteristic of a particular kind of emotional state without being in that kind of state. In chapter 7, a definition of ‘empathy’ is proposed. This definition contains specifications of the three ideas characteristic of the notion of empathy as emotional sharing, and it shows both how the empathizer’s emotion resembles the emotion of the empathee, and how this emotion is caused and experienced.
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| 8. |
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| 9. |
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| 10. |
- Brännäs, Kurt, et al.
(författare)
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A new approach to modelling and forecasting monthly guest nights in hotels
- 2002
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Ingår i: International Journal of Forecasting. - : Elsevier. - 0169-2070 .- 1872-8200. ; 18:1, s. 19-30
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Tidskriftsartikel (refereegranskat)abstract
- Starting from a day-to-day model on hotel specific guest nights we obtain an integer-valued moving average model by cross-sectional and temporal aggregation. The two parameters of the aggregate model reflect mean check-in and the check-out probability. Letting the parameters be functions of dummy and economic variables we demonstrate the potential of the approach in terms of interesting interpretations. Empirical results are presented for a series of Norwegian guests in Swedish hotels. The results indicate strong seasonal patterns in both mean check-in and in the check-out probability. Models based on differenced series are preferred in terms of goodness-of-fit. In a forecast comparison the improvements due to economic variables are small. © 2002 International Institute of Forecasters. Published by Elsevier Science B.V.
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