| 1. |
- Barbu, Andreea R., et al.
(författare)
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A perfusion protocol for highly efficient transduction of intact pancreatic islets of Langerhans
- 2006
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 49:10, s. 2388-2391
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Tidskriftsartikel (refereegranskat)abstract
- Successful gene transfer to pancreatic islets might be a powerful tool for dissecting the biological pathways involved in the functional impairment and destruction of beta cells in type 1 diabetes. In the long run, such an approach may also prove useful for promoting islet graft survival after transplantation in diabetic patients. However, efficient genetic modification of primary insulin-producing cells is limited by the specific compact structure of the pancreatic islet. We present here a whole-pancreas perfusion-based transduction procedure for genetic modification of intact pancreatic islets. We used flow cytometry analysis and confocal microscopy to evaluate the efficiency of in vitro and perfusion-based transduction protocols that use adenoviral and lentiviral vectors expressing green fluorescent protein. Islet cell viability was assessed by fluorescence microscopy and beta cell function was determined via glucose-stimulated insulin secretion. In intact rat and human pancreatic islets, adenoviral and lentiviral vectors mediated gene transfer to about 30% of cells, but they did not reach the inner cellular mass within the islet core. Using the whole-pancreas perfusion protocol, we demonstrate that at least in rodent models the centrally located insulin-producing cells can be transduced with high efficiency, while preserving the structural integrity of the islet. Moreover, islet cell viability and function are not impaired by this procedure. These results support the view that perfusion-based transduction protocols may significantly improve the yield of successfully engineered primary insulin-producing cells for diabetes research.
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| 2. |
- Bülow, Birgitta, et al.
(författare)
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Adrenal incidentaloma - follow-up results from a Swedish prospective study
- 2006
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Ingår i: European journal of endocrinology / European Federation of Endocrine Societies. - : Oxford University Press (OUP). - 0804-4643 .- 1479-683X. ; 154:3, s. 419-23
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To examine the risk of developing adrenal carcinomas and clinically overt hypersecreting tumours during short-term follow-up in patients with adrenal incidentalomas. DESIGN: 229 (98 males and 131 females) patients with adrenal incidentalomas were investigated in a prospective follow-up study (median time 25 months; range 3-108 months). The patients were registered between January 1996 and July 2001 and followed until December 2004. Twenty-seven Swedish hospitals contributed with follow-up results. METHODS: Diagnostic procedures were undertaken according to a protocol including reinvestigation with computed tomography scans after 3-6 months, 15-18 months and 27-30 months, as well as hormonal evaluation at baseline and after 27-30 months of follow-up. Operation was recommended when the incidentaloma size increased or if there was a suspicion of a hypersecreting tumour. RESULTS: The median age at diagnosis of the 229 patients included in the follow-up study was 64 years (range 28-84 years) and the median size of the adrenal incidentalomas when discovered was 2.5 cm (range 1-8 cm). During the follow-up period, an increase in incidentaloma size of > or =0.5 cm was reported in 17 (7.4%) and of > or =1.0 cm was reported in 12 (5.2%) of the 229 patients. A decrease in size was seen in 12 patients (5.2%). A hypersecreting tumour was found in 2% of the hormonally investigated patients: Cushing's syndrome (n = 2) and phaeochromocytoma (n = 1). Eleven patients underwent adrenalectomy, but no cases of primary adrenal malignancy were observed. CONCLUSIONS: Patients with adrenal incidentaloma had a low risk of developing malignancy or hormonal hypersecretion during a short-term follow-up period.
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| 3. |
- Carlsson, Per-Ola, et al.
(författare)
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Carbon monoxide and pancreatic islet blood flow in the rat : inhibition of haem oxygenase does not affect islet blood perfusion
- 2006
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Ingår i: Scandinavian Journal of Clinical and Laboratory Investigation. - : Informa UK Limited. - 0036-5513 .- 1502-7686. ; 66:7, s. 543-548
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To determine whether carbon monoxide, a known gaseous vasorelaxator, affects pancreatic islet blood flow in rats. Material and methods. Sprague-Dawley rats were anaesthetized with thiobutabarbital and injected intravenously with the haem oxygenase inhibitor tin-protoporphyrin IX dichloride ( SnPP; 4, 10 or 20 mg/kg body-weight). After 15 min, blood flow measurements were performed using a microsphere technique. Results. There was a slight increase in mean arterial blood pressure with the highest dose of SnPP. No effects on total pancreatic, islet, duodenal, colonic, renal or adrenal blood flow were seen with any of the applied doses. Conclusions. The findings of this study suggest that the haem oxygenase-carbon monoxide system is likely to be of limited importance in the regulation of blood perfusion to the pancreas, the islets of Langerhans or any of the other studied organs.
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| 4. |
- Eklund, Mona, et al.
(författare)
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Outcomes of activity-based assessment (BIA) compared with standard assessment in occupational therapy
- 2008
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Ingår i: Scandinavian Journal of Occupational Therapy. - : Informa Healthcare. - 1103-8128 .- 1651-2014. ; 15:4, s. 196-203
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Tidskriftsartikel (refereegranskat)abstract
- This study was aimed at investigating the outcomes of an activity-based assessment (BIA) compared with standard assessment (SA) for evaluating clients undergoing psychiatric occupational therapy. Patients admitted to a psychiatric occupational therapy unit were randomized into the BIA or the SA assessment. The outcome indicators were (a) clients' satisfaction with the occupational therapy during the assessment period, (b) clients' awareness of capacities and occupational problems, (c) satisfaction with the assessment among the referring physicians, and (d) outcomes of the intervention following the assessment, in terms of changes in occupational performance and satisfaction. The groups did not differ in awareness of occupational problems, but the BIA group was more satisfied than the SA group with the support of their contact person and with the group leader during the period of assessment. Furthermore, physicians receiving feedback on patients in the BIA group were more satisfied than those receiving feedback on patients in the SA group. However, the groups did not differ concerning change during the treatment period in occupational performance or satisfaction. Thus, there was no difference between the assessment methods regarding the outcomes of the treatment following assessment. Minor advantages from the patients' perspective were found, in terms of better satisfaction in the BIA group, and from the referring physicians' perspective the BIA clearly seemed more satisfying than the SA. Thus, the findings showed that the BIA possessed better qualities than the SA regarding the indicators pertaining to satisfaction, but not concerning awareness of capacities and problems or the outcome of the subsequent treatment.
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| 5. |
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Gunnarsson, Birgitta, 1958-, et al.
(författare)
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The Tree Theme Method in psychosocial occupational therapy – a case study
- 2006
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Ingår i: Scandinavian Journal of Occupational Therapy. - : Informa UK Limited. - 1103-8128 .- 1651-2014. ; 13:4, s. 229-240
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to describe the Tree Theme Method (TTM) as a method for intervention in psychosocial occupational therapy. The TTM is based on theories concerning creative activities and occupational storytelling and story making. In order to exemplify the method a case study of a treatment process with follow up was undertaken. The participant was a female client suffering from anxiety and depression. During an interview the client painted symbolic trees on five different occasions with specific variations of the tree theme: a tree symbolizing her present life, her childhood, adolescence, adulthood, and, finally, a tree representing her future. The trees were used as starting points for the client to tell her life story. The intention was that she would find new strategies for how to change her daily life. Three years later there was a follow up stage where the client painted new trees and told her story. Some life themes were identified. The TTM appears suitable for intervention in psychosocial occupational therapy. In future studies the TTM should be subjected to evaluation research based on several clients in order to develop a deeper understanding of the process and what kind of results changes in the TTM intervention may provide.
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| 10. |
- Gunnarsson, Cecilia, 1970-, et al.
(författare)
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Expression of COX-2 and steroid converting enzymes in breast cancer
- 2006
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Ingår i: Oncology Reports. - 1021-335X .- 1791-2431. ; 16:2, s. 219-224
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Tidskriftsartikel (refereegranskat)abstract
- COX-2 is upregulated in many breast tumors, and one of the products of COX-2 is PGE2 that is suggested to upregulate aromatase through cAMP signaling in breast cancer. Although aromatase can increase the estrogen levels in tumors, 17β-hydroxysteroid dehydrogenase (17HSD) activity is finally needed for the estrone/estradiol regulation. The aim of this study was to investigate if the protein expression of enzymes involved in estrogen synthesis shows covariation with the expression of COX-2. We also wanted to correlate these results with prognosis. We analyzed the expression of COX-2, aromatase, 17HSD1 and 17HSD2 with immunohistochemistry using tissue microarrays composed of 356 primary breast tumors. In the present study COX-2 was correlated to aromatase (P<0.00001), 17HSD1 (P=0.0073), and 17HSD2 (P<0.00001). Patients with ER positive tumors expressing low amounts of 17HSD2 had decreased breast cancer survival (P=0.013). Elevated expression of COX-2 and aromatase was more frequent among larger tumors (P=0.017 and P=0.013). COX-2 expression correlates with the levels of the examined steroid converting enzymes and may contribute to increased estrogen levels in the tumor. In breast cancer cells, the regulatory function of 17HSD2 could be lost, and in the present study patients with low or non-detectable levels of 17HSD2 had worse prognosis than had breast cancer patients with higher levels of the enzyme.
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| 11. |
- Gustafsson, Björn, 1948, et al.
(författare)
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Top incomes in Sweden over three-quarters of a century: a micro data approach
- 2008
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Ingår i: Cambridge Journal of Economics. - : Oxford University Press (OUP). - 0309-166X .- 1464-3545. ; 32:6, s. 963-976
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Tidskriftsartikel (refereegranskat)abstract
- This paper aims to throw light on the development of top incomes in Sweden as well as the causes for change. Using household income data we show that since the first half of the 1980s, real income at the top of the distribution has developed more favourably than for other groups. This contrasts with the changes which occurred prior to the 1980s. Reasons for the rise in the top income share are several: the development of stock prices, tax reform, and the labour market change of top wages increasing more rapidly than others.
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| 12. |
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| 13. |
- Hultström, Michael, et al.
(författare)
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Moderate hypothermia induces a preferential increase in pancreatic islet blood flow in anesthetized rats
- 2007
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Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 293:3, s. R1438-R1443
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to characterize the effects of induced moderate hypothermia on splanchnic blood flow, with particular reference to that of the pancreas and the islets of Langerhans. We also investigated how interference with the autonomic nervous system at different levels influenced the blood perfusion during hypothermia. For this purpose, hypothermia (body temperature of 28°C) was induced by external cooling, whereas normothermic (37.5°C) anesthetized Sprague-Dawley rats were used as controls. Some rats were pretreated with either propranolol, yohimbine, atropine, hexamethonium, or a bilateral abdominal vagotomy. Our findings suggest that moderate hypothermia elicits complex, organ-specific circulatory changes, with increased perfusion noted in the pylorus, as well as the whole pancreas and the pancreatic islets. The pancreatic islets maintain their high blood perfusion through mechanisms involving both sympathetic and parasympathetic mediators, whereas the increased pyloric blood flow is mediated through parasympathetic mechanisms. Renal blood flow was decreased, and this can be prevented by ganglionic blockade and is also influenced by β-adrenoceptors.
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| 14. |
- Jansson, Leif, et al.
(författare)
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Arginase increases total pancreatic and islet blood flow in anaesthetized mice
- 2007
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Ingår i: Upsala Journal of Medical Sciences. - : Uppsala Medical Society. - 0300-9734 .- 2000-1967. ; 112:2, s. 165-173
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Previous studies have demonstrated that the high basal pancreatic islet blood perfusion is crucially dependent on nitric oxide formation. Arginase can interfere with the formation of nitric oxide by limiting substrate availability. The aim of the present study was to evaluate the influence of arginase on islet blood perfusion in anaesthetized mice. METHODS: The blood perfusion of the pancreatic islets was measured with a microsphere technique in anaesthetized NMRI mice after administration of arginase. RESULTS: Arginase administration increased both total pancreatic and islet blood flow to the same degree. Also adrenal blood flow was increased, whereas other organ blood flow values were unaffected. CONCLUSION: Arginase induces a paradoxical increase in pancreatic and islet blood flow, the reasons for which are still unknown.
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| 15. |
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| 16. |
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| 17. |
- Jansson, Leif, et al.
(författare)
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Glucose-induced time-dependent potentiation of insulin release, but not islet blood perfusion, in anesthetized rats
- 2008
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Ingår i: Upsala Journal of Medical Sciences. - 0300-9734 .- 2000-1967. ; 113:1, s. 47-56
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Repeated administration of glucose in vivo leads to a time-dependent potentiation of insulin release. Glucose is also known to stimulate pancreatic islet blood flow, but whether this is associated with a time-dependent potentiation is unknown. We therefore repeatedly administered glucose to anesthetized rats and evaluated effects on insulin release and islet blood flow. METHODS: Male Wistar-Furth rats, anesthetized with thiobutabarbital, were injected intravenously with 1 ml of saline or glucose at times 0, 30 and 60 min. The combinations used were saline + saline + saline (SSS), glucose + saline + saline (GSS), saline + saline + glucose (SSG) and glucose + glucose + glucose (GGG). Regional organ blood flow values were measured 3 min after the final injection with a microsphere technique, and at this time also serum insulin concentrations were determined with ELISA. RESULTS: Serum insulin concentrations as well as total pancreatic, pancreatic islet and duodenal blood flow were higher in SSG and GGG-treated rats when compared to those given SSS and GSS. However, only insulin concentrations, not blood flow values, were higher in GGG rats when compared to SSG animals. CONCLUSIONS: Glucose-induced time-dependent potentiation of insulin release occurs in vivo in thiobutabarbital-anesthetized rats, but is not associated with a further increase in islet blood flow.
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| 18. |
- Jansson, Leif, et al.
(författare)
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Pancreatic islet blood flow during euglycaemic, hyperinsulinaemic clamp in anaesthetized rats
- 2007
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 189:4, s. 319-324
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Previous studies have demonstrated that pancreatic islet blood flow is crucially dependent on blood glucose concentration. Thus, hyperglycaemia increases and hypoglycaemia decreases islet blood perfusion, by a combination of nervous and metabolic signals. The aim of the present study was to evaluate if hyperinsulinaemia, without associated hypoglycaemia, affects islet blood flow. Methods: Thiobutabarbital-anaesthetized Wistar–Furth rats were subjected to an euglycaemic, hyperinsulinaemic clamp, that is they were infused for 60 min with either saline, insulin (18 mU kg−1 min−1), glucose (27 mg kg−1 min−1) or both glucose and insulin. This was followed by islet blood flow measurements with a microsphere technique. Results: Animals receiving only glucose doubled their blood glucose and serum insulin concentrations, whereas rats receiving only insulin had blood glucose concentrations <2 mmol L−1 and a 10-fold increase in serum insulin concentrations. Animals given simultaneous glucose and insulin had normal blood glucose concentrations but a 10-fold increase in serum insulin concentrations. Total pancreatic blood flow was unaffected in all animals. Islet blood flow was increased in hyperglycaemic and decreased in hypoglycaemic rats compared with control rats. Islet blood flow did not differ between clamped and control rats. Conclusions: Serum insulin concentration per se does not affect islet blood flow, whereas the ambient blood glucose concentration is of major importance in this context.
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| 19. |
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| 20. |
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| 21. |
- Karlsson, Diana, et al.
(författare)
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An individual-based network model to evaluate interventions for controlling pneumococcal transmission
- 2008
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Ingår i: BMC Infectious Diseases. - : Springer Science and Business Media LLC. - 1471-2334. ; 8, s. 83-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide, but also a common colonizer of the upper respiratory tract. The emergence and spread of antibiotic resistant pneumococcal strains has threatened effective therapy. The long-term effects of measures aiming to limit pneumococcal spread are poorly understood. Computational modeling makes it possible to conduct virtual experiments that are impractical to perform in real life and thereby allows a more full understanding of pneumococcal epidemiology and control efforts. Methods: We have developed a contact network model to evaluate the efficacy of interventions aiming to control pneumococcal transmission. Demographic data from Sweden during the mid-2000s were employed. Analyses of the model's parameters were conducted to elucidate key determinants of pneumococcal spread. Also, scenario simulations were performed to assess candidate control measures. Results: The model made good predictions of previous findings where a correlation has been found between age and pneumococcal carriage. Of the parameters tested, group size in day-care centers was shown to be one of the most important factors for pneumococcal transmission. Consistent results were generated from the scenario simulations. Conclusion: We recommend, based on the model predictions, that strategies to control pneumococcal disease and organism transmission should include reducing the group size in day-care centers.
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| 22. |
- Lai, En Yin, et al.
(författare)
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Endothelin-1 and pancreatic islet vasculature : studies in vivo and on isolated, vascularly perfused pancreatic islets
- 2007
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Ingår i: American Journal of Physiology. Endocrinology and Metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 292:6, s. E1616-E1623
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Tidskriftsartikel (refereegranskat)abstract
- Endothelin-1 (ET-1) is a potent endothelium-derived vasoconstrictor, which also stimulates insulin release. The aim of the present study was to evaluate whether exogenously administered ET-1 affected pancreatic islet blood flow in vivo in rats and the islet arteriolar reactivity in vitro in mice. Furthermore, we aimed to determine the ET-receptor subtype that was involved in such responses. When applying a microsphere technique for measurements of islet blood perfusion in vivo, we found that ET-1 (5 nmol/kg) consistently and markedly decreased total pancreatic and especially islet blood flow, despite having only minor effects on blood pressure. Neither endothelin A (ET(A)) receptor (BQ-123) nor endothelin-B (ET(B)) receptor (BQ-788) antagonists, alone or in combination, could prevent this reduction in blood flow. To avoid confounding interactions in vivo, we also examined the arteriolar vascular reactivity in isolated, perfused mouse islets. In the latter preparation, we demonstrated a dose-dependent constriction in response to ET-1. Administration of BQ-123 prevented this, whereas BQ-788 induced a right shift in the response. In conclusion, the pancreatic islet vasculature is highly sensitive to exogenous ET-1, which mediates its effect mainly through ET(A) receptors.
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| 23. |
- Lindelöf, Karin S., 1976-
(författare)
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Om vi nu ska bli som Europa : Könsskapande och normalitet bland unga kvinnor i transitionens Polen
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this dissertation is to highlight the discourses surrounding the creation of gender in relation to a number of young, well-educated city women in Poland in the early 21st century. It is my intention to show which “ways of being a woman” that are culturally feasible in Poland in a time of transition – politically, economically, and socially. The study is based on interviews and field notes from a half-year field project in Gdansk-Sopot-Gdynia in 2001.The first chapter discusses theoretical and methodological issues and the second introduces the main themes by analysing a number of essays where Polish students are discussing feminism and women’s situation in Poland and Sweden. Chapter three to six analyses the interviews and other fieldwork material. The courtliness and daily door-opening procedures, which several of the participants in the study regard as typically Polish, are discussed in chapter three. In chapter four, connecting courtliness to issues of love and sexuality deepens this discussion. In chapter five gender equality and feminism is in focus, and in chapter six this discussion is connected to the young women’s ideas of future work and family life. The last chapter concludes and continues the analysis by introducing the concepts of variants and variant-making as a promising way of discussing new identities, institutions and structures in post-socialist and similar settings. The creation of identity appears as a highly intersectional activity in the study. Gender, class, generation, sexuality, nationality, place of residence (city/countryside) are important elements in the young women’s creation of themselves as individuals. The different processes of democratisation, adapting to the EU, privatisation etc., as well as current ideas such as new liberalism, Catholicism and femininity are central to what is happening in Poland today. All these aspects interact in the construction of the identities of the young women.
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| 24. |
- Malm-Renöfält, Birgitta, et al.
(författare)
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Spatial and temporal patterns of species richness in a riparian landscape
- 2005
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Ingår i: Journal of Biogeography. - : Blackwell Publishing. - 0305-0270 .- 1365-2699. ; 32:11, s. 2025-2037
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To test for control of vascular plant species richness in the riparian corridor by exploring three contrasting (although not mutually exclusive) hypotheses: (1) longitudinal patterns in riparian plant species richness are governed by local, river-related processes independent of the regional species richness, (2) riparian plant species richness is controlled by dispersal along the river (longitudinal control), and (3) the variation in riparian plant species richness mirrors variation in regional richness (lateral control).Location: The riparian zones of the free-flowing Vindel River and its surrounding river valley, northern Sweden.Methods: We used data from three surveys, undertaken at 10-year intervals, of riparian reaches (200-m stretches of riverbank) spanning the entire river. In addition, we surveyed species richness of vascular plants in the uplands adjacent to the river in 3.75-km2 large plots along the same regional gradient. We explored the relationship between riparian and upland flora, and various environmental variables. We also evaluated temporal variation in downstream patterns of the riparian flora.Results: Our results suggest that local species richness in boreal rivers is mainly a result of local, river-related processes and dispersal along the corridor. The strongest correlation between species richness and the environment was a negative one between species number and soil pH, but pH varied within a narrow range. We did not find evidence for a correlation between species richness on regional and local scales. We found that the local patterns of species richness for naturally occurring vascular plants were temporally variable, probably in response to large-scale disturbance caused by extreme floods. Most previous studies have found a unimodal pattern of species richness with peaks in the middle reaches of a river. In contrast, on two of three occasions corresponding to major flooding events, we found that the distribution of species richness of naturally occurring vascular plants resembled that of regional diversity: a monotonic decrease from headwater to coast. We also found high floristic similarity between the riparian corridor and the surrounding landscape.Main conclusions: These results suggest that local processes control patterns of riparian species richness, but that species composition is also highly dependent on the regional species pool. We argue that inter-annual variation in flood disturbance is probably the most important factor producing temporal variability of longitudinal species richness patterns.
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| 25. |
- Nowroozalizadeh, Salma, et al.
(författare)
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Studies on toll-like receptor stimuli responsiveness in HIV-1 and HIV-2 infections
- 2009
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Ingår i: Cytokine. - : Elsevier BV. - 1096-0023 .- 1043-4666. ; 46:3, s. 325-331
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Tidskriftsartikel (refereegranskat)abstract
- Background: HIV-1 and HIV-2 are two related viruses with distinct clinical outcomes, where HIV-1 is more pathogenic and transmissible than HIV-2. The pathogenesis of both infections is influenced by the dysregulation and deterioration of the adaptive immune system. However, their effects on the responsiveness of innate immunity are less well known. Here, we report on toll-like receptor (TLR) stimuli responsiveness in HIV-1 or HIV-2 infections. Methods: Whole blood from 235 individuals living in Guinea-Bissau who were uninfected, infected with HIV-1, infected with HIV-2, and/or infected with HTLV-1, was stimulated with TLR7/8 and TLR9 agonists, R-848 and unmethylated CpG DNA. After TLR7/8 and TLR9 stimuli, the expression levels of IL-12 and IFN-alpha were related to gender, age, infection status, CD4(+) T cell counts. and plasma viral load. Results: Defective TLR9 responsiveness was observed in the advanced disease stage, along with CD4(+) T cell loss in both HIV-1 and HIV-2 infections. Moreover, TLR7/8 responsiveness was reduced in HIV-1 infected individuals compared with uninfected controls. Conclusions: Innate immunity responsiveness can be monitored by whole blood stimulation. Both advanced HIVA and HIV-2 infections may cause innate immunity dysregulation. (C) 2009 Elsevier Ltd. All rights reserved.
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| 26. |
- Renöfält, Birgitta Malm, et al.
(författare)
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Spatial patterns of plant invasiveness in a riparian corridor
- 2005
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Ingår i: Landscape Ecology. - : Springer Netherlands. - 0921-2973 .- 1572-9761. ; 20:2, s. 165-176
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of landscape-scale patterns of plant invasiveness can assist in interpreting spatial patterns of plant species richness. We investigated downstream variation in plant invasiveness in the riparian corridor of the free-flowing Vindel River in northern Sweden by introducing seeds of an alien species, Helianthus annuus, in 0.25 m2 plots of natural vegetation from mountain headwaters to the coast and found a significant downstream pattern with middle reaches having the highest invasiveness. We related invasiveness to species richness, both on a reach scale (200-m long stretches of riverbank encompassing the experimental plots) and on the scale of experimental plots. We found no significant correlation between plant invasiveness and species richness, neither at the reach nor at the plot scale. The number of available soil substrates shows a significant positive quadratic relationship with location along the river and substrate fineness shows a near significant negative quadratic relationship with location along the river, with middle reaches having coarser substrates. Several studies have shown that plant species richness in riparian corridors often exhibits a quadratic pattern with highest species richness in the middle reaches of a river, similar to the pattern we found for invasiveness. Although species richness per se might not be a primary factor for invasibility, the same habitat conditions as those supporting plant species richness, can help in explaining large-scale patterns of plant invasion in riparian zones.
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| 27. |
- Ressner, Marcus, et al.
(författare)
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Contrast Biases the Autocorrelation Phase Shift Estimation in Doppler Tissue Imaging
- 2009
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Ingår i: Ultrasound in Medicine and Biology. - : Elsevier BV. - 0301-5629 .- 1879-291X. ; 35:3, s. 447-457
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative assessment of regional myocardial function at rest and during stress with Doppler tissue imaging (DTI) plays an important role in daily routine echocardiography. However, reliable visual analysis is largely dependent on image quality and adequate border delineation, which still remains a challenge in a significant number of patients. In this respect, an ultrasound contrast agent (UCA) is often used to improve visualization in patients with suboptimal image quality. The knowledge of how DTI measurements will be affected by UCA present in the tissue is therefore of significant importance for an accurate interpretation of local myocardial motion. The aim of this paper was to investigate how signal contribution from UCA and nonlinear wave propagation influence the performance of the autocorrelation phase shift estimator used for DTI applications. Our results are based on model experiments with a clinical 2-D grayscale scanner and computational simulations or the DTI velocity estimator for synthetically-derived pulses, simulated bubble echoes and experimentally-sampled RF data of transmitted pulses and backscattered contrast echoes. The results show that destruction of UCA present in the tissue will give rise to an apparent bidirectional velocity bias of individual velocity estimates, but that spatial averaging of individual velocity measurements within a region-of-interest will result in a negative bias (away from the transducer) of the estimated mean or mean peak velocity. The UCA destruction will also have a significant impact on the measured integrated mean velocity over time, i.e., displacement. To achieve improved visualization with UCA during DTI-examinations, we either recommend that it is performed at low acoustic powers, mechanical index <= 0.3, thereby minimizing the effects from bubble rupture, or that each Doppler pulse package is preceded by a destruction burst similar to "Flash imaging" to clear the target area of contrast microbubbles.
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| 28. |
- Ressner, Marcus, 1967-, et al.
(författare)
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Effects of ultrasound contrast agents on Doppler tissue velocity estimation
- 2006
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Ingår i: Journal of the American Society of Echocardiography. - : Elsevier BV. - 0894-7317 .- 1097-6795. ; 19:2, s. 154-164
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Tidskriftsartikel (refereegranskat)abstract
- The combination of Doppler tissue imaging and myocardial contrast echocardiography has the potential to provide information about motion and perfusion of the myocardium in a single examination. The purpose of this study was to establish how the presence of ultrasound contrast agent (UCA) affects measurements of Doppler tissue velocities in vivo and in vitro. We performed echocardiography in 12 patients with ischemic heart disease before and immediately after a slow intravenous infusion of the UCA Optison, using color Doppler tissue imaging to examine the effect of contrast agents in vivo. The myocardial peak systolic velocities and their integrals were analyzed in digitally stored cineloops before and after contrast administration. To distinguish between methodologic and physiologic factors affecting the measurement of tissue velocity in vitro, experiments with a rotating disk and a flow cone phantom were also carried out for the 3 contrast agents: Optison, Sonovue, and Sonazoid. in vivo results show that the values for peak systolic velocity increased by about 10% during contrast infusion, from mean 5.2 +/- 1.8 to 5.7 +/- 2.3 cm/s (P = .02, 95% confidence interval 2%-16%). The increase in myocardial peak systolic velocities was verified in experimental models in which the UCA increased the estimated mean velocity in the order of 5% to 20% for the motion interval of 5 to 7 cm/s, corresponding to the myocardial velocities studied in vivo. The response was similar for all 3 contrast agents and was not affected by moderate variations in concentration of the agent. We have shown that the presence UCA will affect Doppler tissue measurements in vivo and in vitro. The observed bias is presumed to be an effect of harmonic signal contribution from rupturing contrast agent microbubbles and does not indicate biologic or physiologic effects.
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| 29. |
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| 30. |
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| 31. |
- Ressner, Marcus, 1967-, et al.
(författare)
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Ultrasound contrast for perfusion studies
- 2005
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Ingår i: Nordic Baltic Conference Biomedical Engineering and Medical Physics,2005. - Umeå : IFMBE. ; , s. 107-
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Konferensbidrag (refereegranskat)
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| 33. |
- Shao, Linus Ruijin, 1964, et al.
(författare)
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Down-Regulation of Cilia-Localized IL-6R{alpha} by 17{beta}-Estradiol in Mouse and Human Fallopian Tubes.
- 2009
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Ingår i: American journal of physiology. Cell physiology. - : American Physiological Society. - 0363-6143 .- 1522-1563. ; 297:1
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Tidskriftsartikel (refereegranskat)abstract
- The action of Interleukin-6 (IL-6) impacts female reproduction. Although IL-6 was recently shown to inhibit cilia activity in human fallopian tubes in vitro, the molecular mechanisms underlying IL-6 signaling to tubal function remain elusive. Here, we investigate the cellular localization, regulation, and possible function of two IL-6 receptors (IL-6Ralpha and gp130) in mouse and human fallopian tubes in vivo. We show that IL-6Ralpha is restricted to the cilia of epithelial cells in both mouse and human fallopian tubes. Exogenous 17beta-estradiol (E2), but not progesterone (P4), causes a time-dependent decrease in IL-6Ralpha expression which is blocked by the estrogen receptor (ER) antagonist ICI 182,780. Exposure of different ER-selective agonists, PTT or DPN, demonstrated an ER subtype-specific regulation of IL-6Ralphaalpha in mouse fallopian tubes. In contrast to IL-6Ralpha, gp130 was detected in tubal epithelial cells in mice but not in humans. In humans, gp130 was found in the muscle cells and was decreased in the periovulatory and luteal phases during the reproductive cycles, indicating a species-specific expression and regulation of gp130 in the fallopian tube. Expression of tubal IL-6Ralpha and gp130 in IL-6 knockout mice was found to be normal; however, E2 treatment increased IL-6Ralpha, but not gp130, in IL-6 knockout mice compared to wild-type mice. Furthermore, expression levels of IL-6Ralpha, but not gp130, decreased in parallel with estrogenic accelerated oocyte-cumulus complex (OCC) transport in mouse fallopian tubes. Our findings unveil a potential role for cilia-specific IL-6Ralpha in the regulation of OCC transport and suggest an estrogen-regulatory pathway of IL-6Ralpha in the fallopian tube. Key words: estrogen, IL-6R, cilia, fallopian tube.
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| 35. |
- Wennberg, Maria, 1974-, et al.
(författare)
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Fish intake, mercury, long-chain n-3 polyunsaturated fatty acids and risk of stroke in northern Sweden
- 2007
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Ingår i: British Journal of Nutrition. - 0007-1145 .- 1475-2662. ; 98:5, s. 1038-1045
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Tidskriftsartikel (refereegranskat)abstract
- Results of previous studies on fish intake and stroke risk have been inconclusive. Different stroke types have often not been separated. Our aim was to elucidate whether intake of fish, Hg or the sum of proportions of fatty acids EPA (20:5n-3) and DHA (22: 6n-3) influence the risk of haemorrhagic or ischaemic stroke. Within a population-based cohort from a community intervention programme, 369 stroke cases and 738 matched controls were identified and included in the present nested case-control study. Information on fish intake had been recorded at recruitment, i.e. before diagnosis. Hg levels were determined in erythrocyte membranes, also collected at recruitment, and the relative content of fatty acids was measured in erythrocyte membranes or plasma phospholipids. The results showed that in women there was a non-significant decrease in stroke risk with increasing fish intake (OR 0·90 (95 % CI 0·73, 1-11) per meal per week). The risk in women differed significantly (P=0·03) from that in men, in whom the OR for stroke rose with increasing fish intake (OR 1·24 (95 % CI 1·01, 1·51) per meal per week). The corresponding risk in men for Hg was 0·99 (95 % CI 0·93, 1·06), and for the sum of proportions of EPA and DHA 1·08 (95 % CI 0·92, 1·28). We conclude that the relationship between stroke risk and fish intake seems to be different in men and women. Increased levels of EPA and DHA do not decrease the risk for stroke and there is no association between stroke risk and Hg at these low levels.
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| 36. |
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