| 51. |
- Trulsson, Mats, et al.
(författare)
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Orofacial mechanoreceptors in humans : encoding characteristics and responses during natural orofacial behaviors.
- 2002
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Ingår i: Behavioural Brain Research. - 0166-4328 .- 1872-7549. ; 135:1-2, s. 27-33
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Tidskriftsartikel (refereegranskat)abstract
- We used microneurography to characterize stimulus-encoding properties of low-threshold mechanoreceptive afferents in human orofacial tissues. Signals were recorded from single afferents in the infraorbital, lingual and inferior alveolar nerves while localized, controlled, mechanical stimuli were delivered to the facial skin, lips, oral mucosa and teeth. We likewise analyzed activity in these afferents during orofacial behaviors such as speech, chewing and biting. The afferents in the soft tissues functionally resemble four types described in the human hand: hair follicle afferents, slowly adapting (SA) type I and type II afferents and fast adapting (FA) type I afferents. Afferents in the facial skin, lips and buccal mucosa respond not only to contact with environmental objects, but also to contact between the lips, changes in air pressure generated for speech sounds, and to facial skin and mucosa deformations that accompany lip and jaw movements associated with chewing and swallowing. Hence, in addition to exteroceptive information, these afferents provide proprioceptive information. In contrast, afferents terminating superficially in the tongue do not signal proprioceptive information about tongue movements in this manner. They only respond when the receptive field is brought into contact with other intraoral structures or objects, e.g. the teeth or food. All human periodontal afferents adapt slowly to maintained tooth loads. Populations of periodontal afferents encode information about both which teeth are loaded and the direction of forces applied to individual teeth. Most afferents exhibit a markedly curved relationship between discharge rate and force amplitude, featuring the highest sensitivity to changes in tooth load at low forces (below 1 N). Accordingly, periodontal afferents efficiently encode tooth load when subjects first contact, hold, and gently manipulate food by the teeth. In contrast, only a minority of the afferents encodes the rapid and strong force increase generated when biting through food. We conclude, that humans use periodontal afferent signals to control jaw actions associated with intraoral manipulation of food rather than exertion of jaw power actions.
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| 52. |
- Allard, Per, et al.
(författare)
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Caudate nucleus dopamine D-2 receptors in vascular dementia
- 2002
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Ingår i: Dementia and Geriatric Cognitive Disorders. - : S. Karger AG. - 1420-8008 .- 1421-9824. ; 14:1, s. 22-25
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Tidskriftsartikel (refereegranskat)abstract
- Caudate nucleus dopamine (DA) D-2 receptors were studied in patients with vascular dementia (VaD) and in a control group using [H-3]raclopride as a radioligand. There was no significant difference in the number of DA D-2 receptors in the VaD group as compared with controls. The binding affinity was significantly lower in the VaD group. When the VaD group was subdivided into subjects with or without neuroleptic treatment, there were no differences in the numbers of receptors as compared with controls, and the significant differences in binding affinity remained for both VaD subgroups. The present results are. discussed with reference to the previous finding of a reduced density of caudate nucleus DA uptake sites in the same VaD group and to results from studies on DA D-2 receptors in Alzheimer's disease and Parkinson's disease. Copyright (C) 2002 S. Karger AG, Basel.
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| 53. |
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| 54. |
- Bengtsson, Maria, et al.
(författare)
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Bridging Distances: Organizing Boundry-spanning Technology Development Projects
- 2002
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Ingår i: Regional studies. - 0034-3404 .- 1360-0591. ; 36:3, s. 263-274
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Tidskriftsartikel (refereegranskat)abstract
- Technology development is often a boundary-spanning activity where insights and discoveries from different organizations or organizational units are merged into new products or new technical solutions. In some cases, projects of this kind are organized within large multinational firms. In other cases, technology development projects are organized within networks through co-operation between independent companies possessing unique resources that can be utilized as parts of the project. In this paper, we discuss and analyse how distances are bridged in technology development projects. We focus on: (1) the relationship between implicit and explicit knowledge; and (2) different distances inherent in the development effort. Two different bridging processes are proposed as means to overcome distances: a separating-integrating process; and a linking-formalizing process. It is argued that a development project typically runs through either one of these two processes.
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| 55. |
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| 56. |
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| 57. |
- Broome, Michael, et al.
(författare)
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Splanchnic vasoconstriction by angiotensin II is arterial pressure dependent
- 2002
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 46:1, s. 57-63
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Our hypothesis was that splanchnic vasoconstriction by exogenous angiotensin II (Ang II) is significantly potentiated by local mechanisms increasing vasomotor tone and that splanchnic tissue oxygenation during administration of Ang II is perfusion pressure dependent. The aim was to study local splanchnic circulatory effects and tissue oxygenation during intravenous infusion of Ang II at different levels of regional arterial driving pressure in a whole-body large animal model. METHODS: Ang II was infused in incremental doses (0-200 microg x h-1) in anaesthetised instrumented pigs (n=8). Mean superior mesenteric arterial pressure (PSMA) was adjusted by a local variable perivascular occluder. Perivascular ultrasound and laser-Doppler flowmetry were used for measurements of mesenteric venous blood flow and superficial intestinal blood flow, respectively. Intestinal oxygenation was evaluated by oxygen tissue tension (PtiO2) and lactate fluxes. RESULTS: Ang II produced prominent and dose-dependent increases in mesenteric vascular resistance (RSMA) when the intestine was exposed to systemic arterial pressure, but Ang II increased RSMA only minimally when PSMA was artificially kept constant at a lower level (50 mmHg) by the occluder. Although Ang II decreased PtiO2 at a PSMA of 50 mmHg, splanchnic lactate production was not observed. CONCLUSION: We demonstrate that splanchnic vasoconstriction by exogenous Ang II is dependent on arterial driving pressure, suggesting significant potentiation through autoregulatory increases in vasomotor tone. Intestinal hypoxaemia does not seem to occur during short-term infusion of Ang II in doses that significantly increases systemic arterial pressure.
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| 58. |
- Broome, M., et al.
(författare)
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The cardiac effects of intracoronary angiotensin II infusion
- 2002
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Ingår i: Anesthesia and Analgesia. - : Ovid Technologies (Wolters Kluwer Health). - 0003-2999 .- 1526-7598. ; 94:4, s. 787-93, table of contents
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Tidskriftsartikel (refereegranskat)abstract
- Angiotensin II (Ang II) is a potent vasoconstrictor, which recently has been shown to also have significant inotropic effects. Previous results regarding the mechanisms of the acute inotropic effects of Ang II are not conclusive. We designed this study to investigate the local cardiac effects of intracoronary Ang II infusion in doses not affecting systemic circulation. Ang II (2.5-40 microg/h) was infused in the left coronary artery of Yorkshire pigs (n = 9) reaching calculated intracoronary Ang II concentrations of 842 +/- 310, 3342 +/- 1238, and 12448 +/- 4393 pg/mL, respectively. Cardiac systolic and diastolic function was evaluated by analysis of the left ventricular pressure-volume relationship. Coronary flow was measured by using a coronary sinus catheter and the retrograde thermodilution technique. No significant changes were seen in the systolic and diastolic function variables of heart rate, end-systolic elastance, preload recruitable stroke work, the time constant for isovolumetric relaxation, or in coronary vascular resistance and flow. The positive inotropic and chronotropic effects of Ang II seen in previous studies seem thus to be mediated via extracardiac actions of Ang II. Coronary vascular tone is not affected by local Ang II infusion in anesthetized pigs. IMPLICATIONS: The positive inotropic and chronotropic effects of angiotension II (Ang II) seen in previous studies seem to be mediated via extracardiac actions of Ang II. Coronary vascular tone is not affected by local Ang II infusion in anesthetized pigs.
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| 59. |
- 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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| 60. |
- Burén, Jonas, et al.
(författare)
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Dexamethasone impairs insulin signalling and glucose transport by depletion of insulin receptor substrate-1, phosphatidylinositol 3-kinase and protein kinase B in primary cultured rat adipocytes.
- 2002
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Ingår i: European Journal of Endocrinology. - : European Society of Endocrinology. - 0804-4643 .- 1479-683X. ; 146:3, s. 419-29
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Glucocorticoid excess leads to insulin resistance. This study explores the effects of glucocorticoids on the glucose transport system and insulin signalling in rat adipocytes. The interaction between glucocorticoids and high levels of insulin and glucose is also addressed.DESIGN AND METHODS: Isolated rat adipocytes were cultured for 24 h at different glucose concentrations (5 and 15 mmol/l) with or without the glucocorticoid analogue dexamethasone (0.3 micromol/l) and insulin (10(4) microU/ml). After the culture period, the cells were washed and then basal and insulin-stimulated glucose uptake, insulin binding and lipolysis as well as cellular content of insulin signalling proteins (insulin receptor substrate-1 (IRS-1), IRS-2, phosphatidylinositol 3-kinase (PI3-K) and protein kinase B (PKB)) and glucose transporter isoform GLUT4 were measured.RESULTS: Dexamethasone in the medium markedly decreased both basal and insulin-stimulated glucose uptake at both 5 and 15 mmol/l glucose (by approximately 40-50%, P<0.001 and P<0.05 respectively). Combined long-term treatment with insulin and dexamethasone exerted additive effects in decreasing basal, and to a lesser extent insulin-stimulated, glucose uptake capacity (P<0.05) compared with dexamethasone alone, but this was seen only at high glucose (15 mmol/l). Insulin binding was decreased (by approximately 40%, P<0.05) in dexamethasone-treated cells independently of surrounding glucose concentration. Following dexamethasone treatment a approximately 75% decrease (P<0.001) in IRS-1 expression and an increase in IRS-2 (by approximately 150%, P<0.001) was shown. Dexamethasone also induced a subtle decrease in PI3-K (by approximately 20%, P<0.01) and a substantial decrease in PKB content (by approximately 45%, P<0.001). Insulin-stimulated PKB phosphorylation was decreased (by approximately 40%, P<0.01) in dexamethasone-treated cells. Dexamethasone did not alter the amount of total cellular membrane-associated GLUT4 protein. The effects of dexamethasone per se on glucose transport and insulin signalling proteins were mainly unaffected by the surrounding glucose and insulin levels. Dexamethasone increased the basal lipolytic rate (approximately 4-fold, P<0.05), but did not alter the antilipolytic effect of insulin.CONCLUSIONS: These results suggest that glucocorticoids, independently of the surrounding glucose and insulin concentration, impair glucose transport capacity in fat cells. This is not due to alterations in GLUT4 abundance. Instead dexamethasone-induced insulin resistance may be mediated via reduced cellular content of IRS-1 and PKB accompanied by a parallel reduction in insulin-stimulated activation of PKB.
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