| 1. |
- Andersson Lundell, Anna-Carin, 1976, et al.
(författare)
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Development of gut-homing receptors on circulating B cells during infancy.
- 2011
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Ingår i: Clinical immunology. - : Elsevier BV. - 1521-7035 .- 1521-6616. ; 138:1, s. 97-106
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Tidskriftsartikel (refereegranskat)abstract
- B cell gut-homing is mainly mediated by α4β7, CCR9 and CCR10. We here studied the expression of these receptors on B cells from cord blood and from peripheral blood at 1, 4, 18 and 36months of age in a prospective cohort of Swedish infants. The proportion of all B cells expressing α4β7 as well as the fraction of CCR10+ B cells expressing α4β7 was highest in early infancy. Nearly all naïve B cells in all age groups expressed α4β7, whereas the expression on class-switched B cells decreased with age. Moreover, the proportion of both IgA+ and IgG+ B cells expressing α4β7, CCR9 and CCR10 were higher during the first months when compared to adults. In conclusion, the high fraction of circulating IgA+ and IgG+ B cells expressing CCR9 and CCR10 in the first months of life indicates activation of naïve B cells in the gut, coinciding with bacterial colonization.
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| 2. |
- Hasse, Dirk, et al.
(författare)
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Structure of the Homodimeric Glycine Decarboxylase P-protein from Synechocystis sp PCC 6803 Suggests a Mechanism for Redox Regulation
- 2013
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 288:49, s. 35333-35345
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Tidskriftsartikel (refereegranskat)abstract
- Glycine decarboxylase, or P-protein, is a pyridoxal 5-phosphate (PLP)-dependent enzyme in one-carbon metabolism of all organisms, in the glycine and serine catabolism of vertebrates, and in the photorespiratory pathway of oxygenic phototrophs. P-protein from the cyanobacterium Synechocystis sp. PCC 6803 is an (2) homodimer with high homology to eukaryotic P-proteins. The crystal structure of the apoenzyme shows the C terminus locked in a closed conformation by a disulfide bond between Cys(972) in the C terminus and Cys(353) located in the active site. The presence of the disulfide bridge isolates the active site from solvent and hinders the binding of PLP and glycine in the active site. Variants produced by substitution of Cys(972) and Cys(353) by Ser using site-directed mutagenesis have distinctly lower specific activities, supporting the crucial role of these highly conserved redox-sensitive amino acid residues for P-protein activity. Reduction of the 353-972 disulfide releases the C terminus and allows access to the active site. PLP and the substrate glycine bind in the active site of this reduced enzyme and appear to cause further conformational changes involving a flexible surface loop. The observation of the disulfide bond that acts to stabilize the closed form suggests a molecular mechanism for the redox-dependent activation of glycine decarboxylase observed earlier.
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| 3. |
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| 4. |
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| 5. |
- Andersson, Inger, 1964
(författare)
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Health-related quality of life after stem cell transplantation - The firs year
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Health-related quality of life after stem cell transplantation – The first year Inger Andersson Institute of Health and Care Sciences at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Abstract High-Dose Chemotherapy (HDC) followed by Stem Cell Transplantation (SCT) has been proven to be beneficial for a variety of haematological diseases, solid tumours and immune disorders. Despite improved care and treatment, SCT continues to produce significant long-term complications with impaired functioning and distressing symptoms. In this thesis the overall aim was to improve our knowledge about how SCT patients experience different types of transplantations and the effect it may have on their Health-Related Quality of Life (HRQoL) during the first year after SCT. Semi structured interviews were performed and two questionnaires, the European Organization for Research and Treatment of Cancer Quality of Life questionnaire (EORTC QLQ-C30) and the module, High-Dose-Chemotherapy (HDC-19), were administered. Health-related quality of life after allogeneic SCT following Reduced Intensity Conditioning (RIC) and MyeloAblative Conditioning (MAC) were compared. Both groups showed a similar pattern of development over time in functioning and symptoms, albeit more severe in the MAC group. One year after SCT there were no significant differences between the groups in global Quality of Life (QoL). However, RIC patients improved in global QoL back to baseline earlier compared to MAC patients. When allogeneic and autologous patients were compared, RIC patients seemed to recover in the same way as autologous patients and these two groups were closer in their scoring compared to MAC patients. The results emphasize the need to separate the two allogeneic groups when evaluating HRQoL after SCT. Symptoms related to the digestive system like; dry mouth, sore mouth, appetite loss and change of taste together with fatigue were among the most frequent reported symptoms throughout the SCT period for all three groups. In the MAC group, symptoms of dry mouth and change of taste even increased, and one year after SCT these symptoms were more pronounced compared to baseline. Four themes emerged from the data analysis of the interviews and illustrate how the participants described their life from discharge until one year after SCT; obstacles on the road to normality, to be part of a normal life, the chance to be cured overshadow everything and new values in life. The patients described that they felt restricted in life and had problems to manage the response from family and friends. Stem cell transplantation had changed their opportunities in life, meaning that plans for the future had to be altered, sometimes in a negative way. Stem cell transplantation is a demanding procedure that affects the patients HRQoL over a long period of time. Alleviation and management of distressing symptoms and impaired functioning are some of the most important tasks for the health care providers in order to contribute to a better health and life situation for SCT survivors.
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| 6. |
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| 7. |
- Andersson, Inger, 1964, et al.
(författare)
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Patients' perception of health-related quality of life during the first year after autologous and allogeneic stem cell transplantation.
- 2011
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Ingår i: European journal of cancer care. - : Hindawi Limited. - 1365-2354 .- 0961-5423. ; 20:3, s. 368-379
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Tidskriftsartikel (refereegranskat)abstract
- Little attention has been paid to examine health-related quality of life (HRQoL) the first year post-transplant, despite that this period is crucial for returning to normal life and functioning and to prevent delayed psychosocial adjustment. The purpose of the present study was to describe HRQoL after autologous versus allogeneic stem cell transplantations during the first year post-transplant. The allogeneic group was further divided into two groups: allogeneic stem cell transplantation after reduced intensive conditioning and allogeneic stem cell transplantation after myeloablative conditioning. All together 202 patients were enrolled in the study. HRQoL was assessed by the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) and the treatment-specific module High-Dose Chemotherapy (HDC-19). The questionnaires were filled out at six occasions (from inclusion to 12 months after transplantation). The reduced intensive conditioning group seemed to recover in the same way as the autologous group and these two groups were closer in their scoring compared with the myeloablative conditioning group. One month after the transplantation there were no significant differences in change scores between the autologous and reduced intensive conditioning group, and 1 year after the transplantation levels of symptoms and functioning were back to baseline or better. The myeloablative conditioning group, who perceived more symptoms and lower levels of functioning during the whole period, was still impaired in 10 out of 29 scales 1 year after the transplantation and no significant improvements compared with baseline were observed for this group.
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| 8. |
- Andersson, Inger S., et al.
(författare)
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Perceptions of nursing care quality, in acute hospital settings measured by the Karen instruments
- 2013
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Ingår i: Journal of Nursing Management. - : Blackwell Publishing. - 0966-0429 .- 1365-2834. ; 21:1, s. 87-93
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Tidskriftsartikel (refereegranskat)abstract
- Aims The objectives of this study were to measure the quality of nursing care from the perspectives of patients and personnel and to compare these perspectives. Background The perception of quality in nursing care is affected by patient needs and it is common that patients and personnel disagree on the nature of the quality. Thus, it is important to measure the quality from both perspectives. Method A total of 95 patients and 120 personnel from surgical and medical wards at a hospital in Sweden participated. The Karen instruments were used for data collection. A scale index was used for comparison of the perspectives. Results The patients and personnel were satisfied with the quality of care and there were no obvious differences in the total index. The different subscales indicated areas of lower care quality in need of improvement. Conclusion The quality of the care seemed to be satisfactory from the perspectives of both the patients and the personal. Further analysis from the subscale or a variable level is needed to define areas of lower care quality. Implications for Nursing Management Measurements have to be carried out continuously to guarantee care quality over time, as a result of organisational changes and financial cutbacks.
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| 9. |
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| 10. |
- Andersson, Liselott, et al.
(författare)
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Increased free androgen index is associated with hypertension in premenopausal women
- 2011
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Ingår i: Open Journal of Obstetrics and Gynecology. - : Scientific Research Publishing. - 2160-8792 .- 2160-8806. ; 1, s. 228-233
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Increased testosterone and decreased sex hormone-binding globulin (SHBG) are associated with a number of adverse cardiovascular risk factors in postmenopausal women. The aim of this popula-tion-based study of women aged 25 to 50 was to as-sess the relationship between free androgen index (FAI) and cardiovascular risk factors in premeno-pausal women.Methods: A population-based survey of 396 premenopausal women with no hormonal trea- tment was undertaken as part of the Northern Swe-den MONICA study. The study involved question-naires, anthropometry and assays of testosterone and SHBG.Results: Increased FAI was associated with a number of cardiovascular risk factors in premeno-pausal women but this relationship was strongly af-fected by body mass index (BMI). After adjustment for age and BMI, FAI was significantly associated with increased systolic and diastolic blood pressures.Conclusion: Hyperandrogenism is associated with increased blood pressure and these findings empha-size the need to assess cardiovascular risk factors in women with hyperandrogenism of all ages.
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| 11. |
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| 12. |
- Andersson, Lars, et al.
(författare)
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Sprouting capacity from intact root systems of Cirsium arvense and Sonchus arvensis decrease in autumn
- 2013
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Ingår i: Weed research (Print). - : Wiley. - 0043-1737 .- 1365-3180. ; 53:3, s. 183-191
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Tidskriftsartikel (refereegranskat)abstract
- Perennial weeds are often controlled by mechanical means, which aim at stimulating axillary and adventitious buds to sprout. This happens when the apical dominance of the main shoot is removed by defoliation or when the underground system is fragmented. By repeating the measures, the result is a depletion of storage compounds, which weakens the plants and reduces their capacity to grow and reproduce. However, timing is critical. Earlier research has indicated that emergence from fragments of Sonchus arvensis cease during a period in autumn, while the seasonal pattern of sprouting in Cirsium arvense appears to be inconsistent. We studied the emergence pattern of defoliated plants with undisturbed root systems, from late summer to early spring. Potted plants grown outdoors were exhumed at regular intervals, put under forcing conditions for 4weeks, after which shoots above and below soil level were counted and weighed together with the remaining root systems. In both species, the number and weight of emerged shoots decreased during a period in the autumn. In C.arvense, underground shoots were constantly produced during the same period, while fewer underground shoots were present in S.arvensis. For the latter species, apical dominance does not fully explain the effect; thus, endodormancy might be involved. Root weight increased until withering and did not explain the lack of emergence. Our results suggest an impaired sprouting capacity of undisturbed root systems of C.arvense and S.arvensis during SeptemberOctober, which has implications for the timing and method of control of these species.
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| 13. |
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| 14. |
- Andersson, Maria, et al.
(författare)
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Digital support for medication administration : Status-enhancing innovation for care workers?
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Background: There are assumptions that innovative ICT solutions in healthcare can improve the efficiency and contribute to increased quality. Innovation through ICT is also expected to increase status of and attract men to care work.A project aimed at finding innovative ICT solutions was realized between 2009 and 2012. The project involved a healthcare center and two nursing homes. Technicians (all men) were those in the project given the assignment of finding innovative solutions together with staff. Involved in the project were also ICT companies and academic researchers. This research study was undertaken in a nursing home context. A tool for medication administration was under development and to be tested.Purpose; to describe staff’s perceptions of digital support for medication administration and understand staff’s underlying values when arguing for or against the tool.Data collection; focus-group interviews were carried out to collect data. To analyze and interpret the content of the data, a phenomenographic method was used.Findings; Participants questioned the utility and also the need of the ICT solution. Participants also expressed a risk for impaired working environment as an effect of the tool. They also thought the tool would be complicated to use and sometimes would lack in performance. Increased status as an effect of introducing ICT was a belief that was not held by the staff.Conclusions; Setting aside the fact that from the perspective of an outsider, the intention of the project was indeed to do good , staff did not perceive the ICT solution in a positive manner. Politicians and policymakers may be over emphasizing the possibilities of ICT for solving future challenges in healthcare. Focus on technological innovations and a discourse in which care workers are excluded can actually be contra-productive to the possibilities of enhancing the status of care work, which is still predominantly performed by women
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| 15. |
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| 16. |
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| 17. |
- Andersson, Susanne, 1957, et al.
(författare)
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Perceived symptoms in people living with impaired glucose tolerance.
- 2011
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Ingår i: Nursing Research and Practice. - : Hindawi Limited. - 2090-1429 .- 2090-1437. ; 2011:Article ID 937038
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to identify symptoms in people with impaired glucose tolerance (IGT) and describe their experiences of living with the symptoms which they related to their condition. Twenty-one participants, from a cross-sectional population-based study, diagnosed as having IGT, were invited for an interview. The interviews were analyzed in two phases by means of a manifest and latent content analysis. The narratives included seven categories of symptoms (and more than 25 different symptoms) presented by the respondents. This study shows that symptoms such as the patient's own interpretation of different perceptions in the body must be considered, as well as signs and/or objective observations. Symptoms ought to be seen as complementary components in the health encounter and health conversation. The results of this study indicate that health professionals should increase their awareness of the balance between the implicit and the explicit bodily sensations that individuals communicate. Further studies are needed.
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| 18. |
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| 19. |
- Andersson, Susanne, 1957, et al.
(författare)
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The association between self-rated health and impaired glucose tolerance in Swedish adults: A cross-sectional study
- 2013
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Ingår i: Scandinavian Journal of Primary Health Care. - : Informa UK Limited. - 0281-3432 .- 1502-7724. ; 31:2, s. 111-118
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To investigate gender differences in the association between self-rated health (SRH) and impaired glucose tolerance (IGT) in subjects unaware of their glucose tolerance. Design. A cross-sectional population-based study. Setting. The two municipalities of Vara and Skövde in south-western Sweden. Subjects. A total of 2502 participants (1301 women and 1201 men), aged 30–75, were randomly selected from the population. Main outcome measures. IGT was regarded as the outcome measure and SRH as the main risk factor. Results. The prevalence of IGT was significantly higher in women (11.9%) than in men (10.1%), (p = 0.029), as was the prevalence of low SRH (women: 35.4%; men: 22.1%, p = 0.006). Both men and women with low SRH had a poorer risk factor profile than those with high SRH, and a statistically significant crude association between SRH and IGT was found in both men (OR = 2.8, 95% CI 1.8–4.4) and women (OR = 1.5, 95% CI 1.0–2.2, p = 0.033). However, after controlling for several lifestyle factors and biomedical variables, the association was attenuated and remained statistically significant solely in men (OR = 2.3, 95% CI 1.2–4.3). Conclusion. The gender-specific associations found between SRH and IGT suggest that SRH may be a better indicator of IGT in men than in women. Future studies should evaluate the utility of SRH in comparison with objective health measures as a potential aid to health practitioners when deciding whether to screen for IGT and T2DM.
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| 20. |
- Andersson, Susanne, et al.
(författare)
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The association between self-reported lack of sleep, low vitality and impaired glucose tolerance : A Swedish cross-sectional study
- 2013
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Ingår i: BMC Public Health. - : BioMed Central. - 1471-2458. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The increased incidence of impaired glucose tolerance (IGT), are serious public health issues, and several studies link sleeping disorders with increased risk of developing type 2 diabetes, impaired glucose tolerance and insulin resistance (IR). This study explore how self-reported lack of sleep and low vitality, are associated with IGT in a representative Swedish population. Methods. A cross-sectional survey conducted in two municipalities in South-western Sweden. Participants aged 30-75 were randomly selected from the population in strata by sex and age. Altogether, 2,816 participants were surveyed with a participation rates at 76%. Participants with normal glucose tolerance (n=2,314), and those with IGT (n=213) were retained for analyses. The participants answered a questionnaire before the oral glucose tolerance test (OGTT). Associations for questions concerning sleeping disorders, vitality and IGT were analysed using logistic regression and were expressed as odds ratios (OR) with 95% CI. Results: In men a statistically significant age-adjusted association was found between self-reported lack of sleep and IGT: OR 2.4 (95% CI: 1.1-5.4). It did not weaken after further adjustment for body mass index (BMI), smoking, education, and leisure time physical activity 2.3 (1.0-5.5, p=0.044). No such associations were found in females. Corresponding age-adjusted associations between low vitality and IGT in both men 2.8 (1.3-5.8), and women 2.0 (1.2-3.4) were successively lost with increasing adjustment. Conclusions: Insufficient sleep seems independently associated with IGT in men, while low vitality was not independently associated with IGT neither in men nor women, when multiple confounders are considered. IGT should be considered in patients presenting these symptoms, and underlying mechanisms further explored. © 2013 Andersson et al.; licensee BioMed Central Ltd.
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| 21. |
- Andersson, Sonia, et al.
(författare)
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Uneven distribution of human papillomavirus 16111 cervical carcinoma in situ and squamous cell carcinoma in older females : A retrospective database study
- 2014
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Ingår i: Oncology Letters. - : Spandidos Publications. - 1792-1074 .- 1792-1082. ; 8:4, s. 1528-1532
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Tidskriftsartikel (refereegranskat)abstract
- Human papillomavirus (HPV) 16 is the dominant cofactor in cervical cancer development. The present report investigated the age-specific prevalence of HPV16 in cervical carcinoma in situ (CIS) in females attending organised cervical cancer screening. A retrospective observational study was performed based on individual data from two databases. A total of 162 females aged between 20 and 65 years from Uppsala County, Sweden with CIS and an HPV test conducted between 2010 and 2011, preceding or concomitant to CIS diagnosis, were included. Females with cervical squamous cell carcinoma (SCC; n=35) were used for comparison. In total, 96% (n=156) of females with CIS were positive for high-risk HPV; HPV16 was the most prevalent (44.5%), followed by HPV33/52/58 (19.5%), HPV31 (13.1%) and HPV18145 (9.5%). HPV16 was most frequently detected in females with CIS aged between 20 and 29 years (73.6%) and least frequently detected in those aged between 50 and 65 years (33.3%), with a statistically significant age-specific difference (P=0.001). Among the HPV16-positive females, multiple infections were most frequent in the younger age groups. The prevalence of HPV16 in females with CIS decreased with age, whereas a high prevalence of HPV16 remained in females with SCC. These results may indicate that HPV16 has increased oncogenic potential in older females.
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| 22. |
- Andersson Shams Hakimi, Caroline, et al.
(författare)
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Effects of fibrinogen and platelet supplementation on clot formation and platelet aggregation in blood samples from cardiac surgery patients.
- 2014
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Ingår i: Thrombosis research. - : Elsevier BV. - 1879-2472 .- 0049-3848. ; 134:4, s. 895-900
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Tidskriftsartikel (refereegranskat)abstract
- Bleeding after cardiac surgery may be caused by surgical factors, impaired haemostasis, or a combination of both. Transfusion of blood products is used to improve haemostasis, but little is known about what combination is optimal. We hypothesized that addition of both fibrinogen and platelets to blood samples from cardiac surgery patients would improve clot formation and platelet aggregation to a greater extent than if the components were added separately.
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| 23. |
- Ansari, Daniel, et al.
(författare)
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Positron emission tomography in malignancies of the liver, pancreas and biliary tract - indications and potential pitfalls.
- 2013
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 1502-7708 .- 0036-5521. ; 48:3, s. 259-265
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Forskningsöversikt (refereegranskat)abstract
- Abstract Malignancies of the hepato-pancreatico-biliary (HPB) system are relatively common and generally characterized by a dismal prognosis. Positron emission tomography (PET) is a functional imaging technique that has emerged as an important modality in oncological decision-making. The principal radiopharmaceutical in PET imaging is the glucose analog (18)F-fluorodeoxyglucose, which is able to detect altered glucose metabolism in malignant tissue. PET is typically used in conjunction with computed tomography (CT), and previous studies have supported several uses of PET/CT in HPB malignancies, including staging, differential diagnostics and monitoring of treatment response and progress of disease. A review of PET/CT in the context of HPB malignancies will be presented, including indications and potential pitfalls.
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| 24. |
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| 25. |
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| 26. |
- Boström, Ullalena, et al.
(författare)
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Seasonal variation in sprouting capacity from intact rhizome systems of three perennial weeds.
- 2013
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Ingår i: Weed research (Print). - : Wiley. - 0043-1737 .- 1365-3180. ; 53:5, s. 387-398
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Tidskriftsartikel (refereegranskat)abstract
- The three rhizomatous perennials Elytrigia repens, Equisetum arvense and Tussilago farfara are all problematic in Scandinavian agriculture, due to their low susceptibility to soil cultivation. While repeated soil tillage is a fundamental part of the integrated control of these species, it is highly energy consuming and inefficient during periods when little sprout regrowth occurs. Substituting cultivation with mowing will reduce the environmental impact and labour costs, but its efficiency will still depend on the capacity of plants to sprout. Therefore, we studied the seasonal pattern in emergence and rhizome biomass allocation from July to April in six populations for each of the species. Plants were grown outdoors in pots buried in soil and exhumed at regular intervals in a two-year experiment. In all three species, biomass allocation to rhizomes continued until late in the autumn. Emergence was severely impaired in E.arvense and T.farfara in September-October, while in E.repens, there was no such reduction in the number of emerged shoots. However, in the latter species, the shoot/rhizome ratio decreased and remained low until the plants had been exposed to a period of low temperatures. The increase in shoot/rhizome ratio for E.repens coincided with the resumed capacity to emerge for E.arvense and T.farfara. These results imply that there is no need to repeat a defoliation of E.arvense and T.farfara, if carried out in September-October. However, removal of the aerial plant parts early in the autumn is important to interrupt the upload of storage compounds to the rhizome systems of all species.
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| 27. |
- Brolen, Gabriella, et al.
(författare)
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Hepatocyte-like cells derived from human embryonic stem cells specifically via definitive endoderm and a progenitor stage
- 2010
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 1873-4863 .- 0168-1656. ; 145:3, s. 284-294
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Tidskriftsartikel (refereegranskat)abstract
- Human embryonic stem cells offer a potential unlimited supply for functional hepatocytes, since they can differentiate into hepatocyte-like cells displaying a characteristic hepatic morphology and expressing various hepatic markers. These cells could be used in various applications such as studies of drug metabolism and hepatotoxicity, which however, would require a significant expression of drug metabolizing enzymes. To derive these cells we use a stepwise differentiation protocol where growth- and maturation factors are added. The first phase involves the formation of definitive endoderm. Next, these cells are treated with factors known to promote the induction and proliferation towards hepatic progenitor cell types. In the last phase the cells are terminally differentiated and maturated into functional hepatocyte-like cells. The cultures were characterized by analysis of endodermal or hepatic markers and compared to cultures derived without induction via definitive endoderm. Hepatic functions such as urea secretion, glycogen storage, indocyanine green uptake and secretion, and cytochrome P450-expression and activity were evaluated. The DE-Hep showed a hepatocyte morphology with sub-organized cells and exhibited many liver-functions including transporter activity and capacity to metabolize drugs specific for important cytochrome P450 sub-families. This represents an importantstep in differentiation of hESC into functional hepatocytes. (C) 2009 Elsevier B.V. All rights reserved.
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| 28. |
- Chapman, Henry N, et al.
(författare)
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Femtosecond X-ray protein nanocrystallography.
- 2011
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 470:7332, s. 73-7
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Tidskriftsartikel (refereegranskat)abstract
- X-ray crystallography provides the vast majority of macromolecular structures, but the success of the method relies on growing crystals of sufficient size. In conventional measurements, the necessary increase in X-ray dose to record data from crystals that are too small leads to extensive damage before a diffraction signal can be recorded. It is particularly challenging to obtain large, well-diffracting crystals of membrane proteins, for which fewer than 300 unique structures have been determined despite their importance in all living cells. Here we present a method for structure determination where single-crystal X-ray diffraction 'snapshots' are collected from a fully hydrated stream of nanocrystals using femtosecond pulses from a hard-X-ray free-electron laser, the Linac Coherent Light Source. We prove this concept with nanocrystals of photosystem I, one of the largest membrane protein complexes. More than 3,000,000 diffraction patterns were collected in this study, and a three-dimensional data set was assembled from individual photosystem I nanocrystals (∼200nm to 2μm in size). We mitigate the problem of radiation damage in crystallography by using pulses briefer than the timescale of most damage processes. This offers a new approach to structure determination of macromolecules that do not yield crystals of sufficient size for studies using conventional radiation sources or are particularly sensitive to radiation damage.
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| 29. |
- Forsgren, Nina, 1979-
(författare)
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Structural studies of the surface adhesin SspB from Streptococcus gordonii
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Surface proteins on microorganisms that build up the oral biofilm are key players in the formation of the biofilm. Antigen I/II proteins are surface adhesins found on virtually all oral streptococci and share a conserved multi-domain architecture. These adhesins bind surface components on other bacteria and on host cells. Thus, they are crucial for the development of the biofilm. The objective of this thesis work is the structural characterization of the large multi-domain Antigen I/II protein SspB from the primary colonizing commensal bacterium Streptococcus gordonii. The crystal structure of the variable domain of SspB was determined to 2.3 Å resolution. The domain comprises a β-supersandwich and a putative binding cleft stabilized by a calcium ion. Despite high similarity in the overall structure, the cleft within SspB is significantly smaller than the cleft within the homologous protein from Streptococcus mutans, indicating that different substrates may bind in the clefts. A screen for carbohydrate binding resulted in no hits for interaction with the SspB variable domain suggesting that the cleft may not be suitable for binding sugars. This thesis also presents the high resolution 1.5 Å structure of a truncated C-terminal domain of SspB, the first of an Antigen I/II C-domain. The structure contains two structurally related domains, each containing one calcium ion and one intramolecular isopeptide bond. The SspB protein shares the feature of intramoleular isopeptide bonds with other surface proteins from Gram positive bacteria, such as pili from Streptococcus pyogenes and Corynebacterium diphtheriae. Intramolecular isopeptide bonds are suggested to be a common feature for retaining stability in a harsh environment. The SspB adherence region, shown to be the recognition motif for Porphyromonas gingivalis attachment to S. gordonii, protrudes from the core protein as a handle available for recognition. In conclusion, this thesis work has provided new knowledge about the SspB protein and increased the understanding of the common structure of AgI/II proteins.
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Hagerman, Inger, et al.
(författare)
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Effects on heart rate variability by artificially generated indoor nano-sized particles in a chamber study
- 2014
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 88, s. 165-171
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Tidskriftsartikel (refereegranskat)abstract
- Background: Airborne particles are associated with increased morbidity and mortality due to respiratory and cardiovascular diseases in polluted areas. There is a growing interest in nano-sized particles with diameter < 100 nm and their potential health effects. Heart rate variability (HRV) is a noninvasive method for cardiovascular risk prediction in high prevalent groups. Aim of study: The aim was to evaluate the impact of nano-sized indoor air particles on HRV for healthy and adult females. Methods: All exposures were performed as controlled chamber experiments with particle exposure from burning candles, terpene + ozone reactions or filtered air in a double-blind cross over design. Twenty-two healthy females were investigated during 10 min periods at different exposures and the reactivity in high frequency (HF) spectral band of HRV were computed. Results: Heart rate was unchanged from baseline values in all groups during all experimental settings. HF power of HRV tended to increase during exposure to particles from burning candle while particles from terpene + ozone reactions tended to decrease HF power. Conclusions: Exposure to nano-sized particles of burning candles or terpene + ozone reactions results in different patterns of heart rate variability, with signs of altered autonomic cardiovascular control. Practical implications: This study indicates that the HRV method may be used for information on physiological responses of exposure to different nano-sized particles and contribute to the understanding of mechanisms behind health effects of particle exposures. (C) 2014 The Authors. Published by Elsevier Ltd.
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| 34. |
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| 35. |
- Hamlin, Helene, et al.
(författare)
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Immunmedierade sjukdomar hos hund
- 2012
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Ingår i: Svensk Veterinärtidning. - 0346-2250. ; 64, s. 37-40
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 36. |
- Hantke, Max F., et al.
(författare)
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High-throughput imaging of heterogeneous cell organelles with an X-ray laser
- 2014
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Ingår i: Nature Photonics. - : Springer Science and Business Media LLC. - 1749-4885 .- 1749-4893. ; 8:12, s. 943-949
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Tidskriftsartikel (refereegranskat)abstract
- We overcome two of the most daunting challenges in single-particle diffractive imaging: collecting many high-quality diffraction patterns on a small amount of sample and separating components from mixed samples. We demonstrate this on carboxysomes, which are polyhedral cell organelles that vary in size and facilitate up to 40% of Earth's carbon fixation. A new aerosol sample-injector allowed us to record 70,000 low-noise diffraction patterns in 12 min with the Linac Coherent Light Source running at 120 Hz. We separate different structures directly from the diffraction data and show that the size distribution is preserved during sample delivery. We automate phase retrieval and avoid reconstruction artefacts caused by missing modes. We attain the highest-resolution reconstructions on the smallest single biological objects imaged with an X-ray laser to date. These advances lay the foundations for accurate, high-throughput structure determination by flash-diffractive imaging and offer a means to study structure and structural heterogeneity in biology and elsewhere.
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| 37. |
- Hasse, Dirk, et al.
(författare)
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Crystallization and preliminary X-ray diffraction analyses of the homodimeric glycine decarboxylase (P-protein) from the cyanobacterium Synechocystis sp. PCC 6803.
- 2010
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Ingår i: Acta Crystallographica. Section F. - 1744-3091 .- 1744-3091. ; 66:Pt 2, s. 187-191
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Tidskriftsartikel (refereegranskat)abstract
- Glycine decarboxylase, or P-protein, is a major enzyme that is involved in the C(1) metabolism of all organisms and in the photorespiratory pathway of plants and cyanobacteria. The protein from Synechocystis sp. PCC 6803 is a homodimer with a mass of 215 kDa. Recombinant glycine decarboxylase was expressed in Escherichia coli and purified by metal-affinity, ion-exchange and gel-filtration chromatography. Crystals of P-protein that diffracted to a resolution of 2.1 A were obtained using the hanging-drop vapour-diffusion method at 291 K. X-ray diffraction data were collected from cryocooled crystals using synchrotron radiation. The crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 96.30, b = 135.81, c = 179.08 A.
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| 38. |
- Hofsten, Anna, et al.
(författare)
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Case seminars open new doors to understanding : nursing students’ experiences of learning
- 2012
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Konferensbidrag (refereegranskat)abstract
- BackgroundThe Case Method is a teaching method in which cases from real life inspire students to actively seek knowledge that they discuss in seminars. During seminars, different solutions and ideas are written in a structured way on the white board. Hofsten (2010) described how case seminars in cardiology help nursing students share knowledge and identify possible ways of dealing with patients.Summary of workTo deepen the understanding of learning in case seminars, we asked students in a very different educational context, psychiatric care, about their experiences. Written narratives from 44 nursing students were analyzed using a content analysis.Summary of resultsThe students described the importance of different perspectives and of seeing a context and of learning in a climate that promotes discussions; they felt that the overview on the white board encouraged students to participate. Different categories and the preliminary themes To reflect on thoughts, To give and take, and To see what is said are shown in Figure 1. When we presented these results to the students, most reported recognizing our description of learning situation to a great or very great degree; see Figure 2.ConclusionsThe Case Method seems to involve students in a way that deepens their understanding and this effect seems to be independent of subject or teacher
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| 39. |
- Innala, Eva, et al.
(författare)
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Women with acute intermittent porphyria have a defect in 5 alpha-steroid production during the menstrual cycle
- 2012
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Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - : John Wiley & Sons. - 0001-6349 .- 1600-0412. ; 91:12, s. 1445-1452
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To measure serum concentrations of progesterone, estradiol and 5 alpha- and 5 beta-reduced progesterone metabolites in the follicular and luteal phases of the menstrual cycle in women with latent acute intermittent porphyria and manifest acute intermittent porphyria in comparison with healthy control women. Design. A descriptive study with repeated measurements during a complete, ovulatory menstrual cycle. Setting. University hospital out-patient clinic. Population. Thirty-two women with DNA-diagnosed acute intermittent porphyria and 20 healthy control women. Methods. Blood samples for serum progesterone, estradiol, allopregnanolone and pregnanolone were drawn on predefined menstrual cycle days, twice in the follicular phase and three times in the luteal phase. Serum levels of estradiol and progesterone were analysed with commercial kits. Allopregnanolone and pregnanolone levels were analysed with radioimmunoassay following diethylether extraction and celite column chromatography. Main outcome measures. Changes in serum levels of progesterone, estradiol, allopregnanolone and pregnanolone throughout the menstrual cycle. Results. Women with acute intermittent porphyria displayed lower serum concentrations of allopregnanolone in comparison with healthy control women, the difference being most prominent in the luteal phase (p < 0.001). Levels of pregnanolone did not differ significantly between groups. No significant difference was found between women with latent acute intermittent porphyria and manifest acute intermittent porphyria. Conclusions. Decreased levels of the 5 alpha-reduced progesterone metabolite allopregnanolone were found in the menstrual cycle of women with acute intermittent porphyria. This has not been reported previously and could indicate a reduced 5 alpha-reductase type 1 capacity in the ovary and liver among these women.
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| 40. |
- Isaxon, Christina, et al.
(författare)
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A Novel System for Source Characterization and Controlled Human Exposure to Nanoparticle Aggregates Generated During Gas–Metal Arc Welding
- 2013
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Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 1521-7388 .- 0278-6826. ; 47:1, s. 52-59
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in Undetermined The aim of this study was to achieve a method to perform detailed characterization and human exposure studies of nanosized and nanostructured aerosol particles. The source chosen was mild steel, active gas, arc welding fume. The setup consisted of a generation chamber, where welding can be performed, connected to an airtight stainless steel 22 m(3) exposure chamber. Instrumentation, consisting of a tapered element oscillating microbalance, a scanning mobility particle sizer, and a sampler for electron microscopy and particle-induced X-ray emission analysis was connected to the stainless steel chamber. The feasibility of the system for human exposure studies was evaluated by exposing 31 human volunteers, in groups of three, to a test aerosol containing 1 mg/m(3) welding fumes and to conditioned, filtered air. The results show that an aerosol that accurately represents dilute welding fume exposures that occur in workplaces can be produced in a controlled manner, and that the experimental setup can be used for 6 h, double-blind, exposures of human subjects. Particle mass concentration levels could be varied from <5 mu g/m(3) to more than 1000 mu g/m(3). Fumes from metal active gas welding showed a unimodal size distribution with a mean mobility diameter of 160 nm, transmission electron microscopy showed aggregates with a clearly nanosized structure.
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| 41. |
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| 42. |
- Jacobsen, Mette, et al.
(författare)
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Characterisation of five candidate genes within the ETEC F4ab/ac candidate region in pigs
- 2011
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Ingår i: BMC Research Notes. - : Springer Science and Business Media LLC. - 1756-0500. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundEnterotoxigenic Escherichia coli (ETEC) that express the F4ab and F4ac fimbriae is a major contributor to diarrhoea outbreaks in the pig breeding industry, infecting both newborn and weaned piglets. Some pigs are resistant to this infection, and susceptibility is inherited as a simple dominant Mendelian trait. Indentifying the genetics behind this trait will greatly benefit pig welfare as well as the pig breeding industry by providing an opportunity to select against genetically susceptible animals, thereby reducing the number of diarrhoea outbreaks. The trait has recently been mapped by haplotype sharing to a 2.5 Mb region on pig chromosome 13, a region containing 18 annotated genes.FindingsThe coding regions of five candidate genes for susceptibility to ETEC F4ab/ac infection (TFRC, ACK1, MUC20, MUC4 and KIAA0226), all located in the 2.5 Mb region, were investigated for the presence of possible causative mutations. A total of 34 polymorphisms were identified in either coding regions or their flanking introns. The genotyping data for two of those were found to perfectly match the genotypes at the ETEC F4ab/ac locus, a G to C polymorphism in intron 11 of TFRC and a C to T silent polymorphism in exon 22 of KIAA0226. Transcriptional profiles of the five genes were investigated in a porcine tissue panel including various intestinal tissues. All five genes were expressed in intestinal tissues at different levels but none of the genes were found differentially expressed between ETEC F4ab/ac resistant and ETEC F4ab/ac susceptible animals in any of the tested tissues.ConclusionsNone of the identified polymorphisms are obvious causative mutations for ETEC F4ab/ac susceptibility, as they have no impact on the level of the overall mRNA expression nor predicted to influence the composition of the amino acids composition. However, we cannot exclude that the five tested genes are bona fide candidate genes for susceptibility to ETEC F4ab/ac infection since the identified polymorphism might affect the translational apparatus, alternative splice forms may exist and post translational mechanisms might contribute to disease susceptibility.
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| 43. |
- Jacobsen, M, et al.
(författare)
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Refined candidate region specified by haplotype sharing for Escherichia coli F4ab/F4ac susceptibility alleles in pigs
- 2010
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Ingår i: Animal Genetics. - : Wiley. - 0268-9146 .- 1365-2052. ; 41:1, s. 21-25
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Tidskriftsartikel (refereegranskat)abstract
- Infection of the small intestine by enterotoxigenic Escherichia coli F4ab/ac is a major welfare problem and financial burden for the pig industry. Natural resistance to this infection is inherited as a Mendelian recessive trait, and a polymorphism in the MUC4 gene segregating for susceptibility/resistance is presently used in a selection programme by the Danish pig breeding industry. To elucidate the genetic background involved in E. coli F4ab/ac susceptibility in pigs, a detailed haplotype map of the porcine candidate region was established. This region covers approximately 3.7 Mb. The material used for the study is a three generation family, where the founders are two Wild boars and eight Large White sows. All pigs have been phenotyped for susceptibility to F4ab/ac using an adhesion assay. Their haplotypes are known from segregation analysis using flanking markers. By a targeted approach, the candidate region was subjected to screening for polymorphisms, mainly focusing on intronic sequences. A total of 18 genes were partially sequenced, and polymorphisms were identified in GP5, CENTB2, APOD, PCYT1A, OSTalpha, ZDHHC19, TFRC, ACK1, MUC4, MUC20, KIAA0226, LRCH3 and MUC13. Overall, 227 polymorphisms were discovered in the founder generation. The analysis revealed a large haplotype block, spanning at least 1.5 Mb around MUC4, to be associated with F4ab/ac susceptibility.
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| 44. |
- Jansson, Inger, 1964-, et al.
(författare)
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Evaluation of documented nursing care plans by the use of nursing-sensitive outcome indicators
- 2010
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Ingår i: Journal of Evaluation In Clinical Practice. - Oxford : Blackwell Publishing. - 1356-1294 .- 1365-2753. ; 16:3, s. 611-618
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Rationale and aim: There is a lack of evidence that nursing care plans affect patient outcomes. The aim of the present study was to evaluate whether documented nursing care plans affect patient outcomes by the use of nursing-sensitive outcome indicators. Method: A retrospective, cross-sectional design with patients surveyed at time of discharge from two hospital units for patients with stroke and after 2-3 weeks at home. The control unit (A) did not employ care plans. The intervention unit (B) used care plans on a daily basis. Outcome was measured by 'the National Stroke Register' and the two questionnaires: 'Quality of patients' perspective' and 'Euroquol five dimensions'. Data were collected over a 5-month period (October 2007-February 2008). Results: In total, 87 patients were included in the study. Patient characteristics in the two groups at admission and the health-related quality of life 2 to 3 weeks after discharge were similar. The patients from unit B were more satisfied with individual care (P = 0.03) and participation (P = 0.007). Unit B also had a shorter length of stay (P = 0.004). Conclusions: The effects of documented care plans are difficult to evaluate from a patient perspective, as many factors can improve the outcome. However, documentation of care plans is a prerequisite for measuring the quality and outcome of the care provided. This small study indicates that documented care plans may affect patient satisfaction regarding individual care, participation and length of hospital stay.
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| 45. |
- Johansson, Inger, 1953, et al.
(författare)
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Lower incidence of CMV infection and acute rejections with valganciclovir
- 2013
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Ingår i: BMC Infectious Diseases. - : Springer Science and Business Media LLC. - 1471-2334. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Background Cytomegalovirus (CMV) is the most common opportunistic infection following lung transplantation. CMV replication in the lung allograft is described as accelerating the development of bronchiolitis obliterans syndrome (BOS).Finding a strategy to prevent CMV infection is an important issue. Methods We performed a retrospective, single-centre study of 114 lung transplant recipients (LTRs) who underwent lung transplantation from January 2001 to December 2006. In a smaller cohort of 88 CMV seropositive (R+) LTRs, three months of valganciclovir prophylaxis (2004-2006) was compared to three months of oral ganciclovir (2001-2003) with respect to the incidence of CMV infection/disease, the severity of CMV disease, acute rejection, BOS-free 4 year survival and 4 year survival. In the whole group of 114 LTRs the impact of CMV infection on long-term survival (BOS free 4 year survival and 6 year survival) was assessed. Results For the cohort of 88 CMV seropositive LTRs, the incidence of CMV infection/disease at one year was lower in the valganciclovir group compared to the ganciclovir group (24% vs. 54%, p = 0.003). There was a tendency towards reduced CMV disease, from 33% to 20% and a significant lower incidence of asymptomatic CMV infection (22% vs. 4%, p = 0.005). A lower incidence of acute rejection was observed in the valganciclovir group. However, there was no significant difference between the two groups in BOS free 4 year survival and 4 year survival. For the entire group of 114 LTRs, BOS-free 4 year survival for recipients with CMV disease was (32%, p = 0.005) and among those with asymptomatic CMV infection (36%, p = 0.061) as compared with patients without CMV infection (69%). Six year survival was lower among patients with CMV disease, (64%, p = 0.042) and asymptomatic CMV infection (55%, p = 0.018) than patients without CMV infection (84%). Conclusions A lower incidence of CMV infection/disease and acute rejections was observed with valganciclovir (3 months) when compared to oral ganciclovir (3 months). The long-term impact of CMV infection/disease was significant for BOS-free survival and survival.
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| 46. |
- Johanssson, Inger, et al.
(författare)
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Cytomegalovirus and long-term outcome after lung transplantation in Gothenburg, Sweden.
- 2010
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Ingår i: Scandinavian journal of infectious diseases. - : Informa UK Limited. - 1651-1980 .- 0036-5548. ; 42:2, s. 129-36
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Tidskriftsartikel (refereegranskat)abstract
- Prophylaxis with ganciclovir has decreased the initially high morbidity related to cytomegalovirus (CMV) after lung transplantation, but the optimal length of prophylaxis and the long-term outcome have not yet been established. The impact of CMV on the short- and long-term outcome was studied in 187 lung transplant recipients in Gothenburg, Sweden, 1990-2002. Among CMV-seronegative patients receiving grafts from seropositive donors (D+/R-), 88% developed CMV disease, 40% if both donor and recipient were CMV-seropositive (D+/R+) and 26% if only the recipient was CMV-seropositive (D-/R+). Among CMV-seropositive recipients (R+) on oral acyclovir prophylaxis, 38% developed CMV disease, as compared with 39% on intravenous ganciclovir for 4 weeks and 28% on oral ganciclovir for 14 weeks. On average, CMV disease appeared at 41 days in the R+ on acyclovir prophylaxis, at 75 days on 4 weeks of i.v. ganciclovir and at 162 days on 14 weeks of oral ganciclovir. CMV disease was associated with a statistically significant increased risk of developing chronic rejection (bronchiolitis obliterans syndrome) at both 1 and 2 y after transplantation. CMV disease also had a significant negative impact on survival, with a 10-y survival of only 32% as compared with 53% after asymptomatic CMV infection and 57% with no CMV.
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| 47. |
- Kaaks, Rudolf, et al.
(författare)
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Insulin-like growth factor I and risk of breast cancer by age and hormone receptor status : A prospective study within the EPIC cohort
- 2014
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 134:11, s. 2683-2690
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Tidskriftsartikel (refereegranskat)abstract
- Experimental evidence shows cross-talk in mammary cells between estrogen, insulin-like growth factor I (IGF-I) and their respective receptors and possible synergistic effects of estrogen receptor (ER) activation and increased IGF-I signaling with regard to breast tumor development, and epidemiological evidence suggests that circulating IGF-I levels may be related more to the risk of ER-positive than ER-negative breast cancer. Using a case–control study nested within the prospective European EPIC cohort (938 breast cancer cases and 1,394 matched control subjects), we analyzed the relationships of prediagnostic serum IGF-I levels with the risk of estrogen and progesterone receptor-positive and -negative breast tumors. IGF-I levels were positively associated with the risk of ER+ breast tumors overall (pre- and postmenopausal women combined, odds ratio (OR)Q4-Q1 = 1.41 [95% confidence interval (CI) 1.01–1.98] for the highest vs. lowest quartile; OR = 1.17 [95% CI 1.04–1.33] per 1-standard deviation (SD) increase in IGF-I, ptrend = 0.01) and among women who were diagnosed with breast cancer at 50 years or older (ORQ3-Q1 = 1.38 [95% CI 1.01–1.89]; OR = 1.19 [95% CI 1.04–1.36] per 1-SD increase in IGF-I, ptrend = 0.01) but not with receptor-positive disease diagnosed at an earlier age. No statistically significant associations were observed for ER− breast tumors overall and by age at diagnosis. Tests for heterogeneity by receptor status of the tumor were not statistically significant, except for women diagnosed with breast cancer at 50 years or older (phet = 0.03 for ER+/PR+ vs. ER−/PR− disease). Our data add to a global body of evidence indicating that higher circulating IGF-I levels may increase risk specifically of receptor-positive, but not receptor-negative, breast cancer diagnosed at 50 years or older.
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| 48. |
- Kapralov, Maxim V, et al.
(författare)
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Changes in Rubisco kinetics during the evolution of C4 photosynthesis in Flaveria (Asteraceae) are associated with positive selection on genes encoding the enzyme.
- 2011
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Ingår i: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 28:4, s. 1491-1503
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Tidskriftsartikel (refereegranskat)abstract
- Rubisco, the primary photosynthetic carboxylase, evolved 3-4 billion years ago in an anaerobic, high CO(2) atmosphere. The combined effect of low CO(2) and high O(2) levels in the modern atmosphere, and the inability of Rubisco to distinguish completely between CO(2) and O(2), leads to the occurrence of an oxygenation reaction that reduces the efficiency of photosynthesis. Among land plants, C(4) photosynthesis largely solves this problem by facilitating a high CO(2)/O(2) ratio at the site of Rubisco that resembles the atmosphere in which the ancestral enzyme evolved. The prediction that such conditions favor Rubiscos with higher kcat(CO2) and lower CO(2)/O(2) specificity (S(C/O)) is well supported, but the structural basis for the differences between C(3) and C(4) Rubiscos is not clear. Flaveria (Asteraceae) includes C(3), C(3)-C(4) intermediate, and C(4) species with kinetically distinct Rubiscos, providing a powerful system in which to study the biochemical transition of Rubisco during the evolution from C(3) to C(4) photosynthesis. We analyzed the molecular evolution of chloroplast rbcL and nuclear rbcS genes encoding the large subunit (LSu) and small subunit (SSu) of Rubisco from 15 Flaveria species. We demonstrate positive selection on both subunits, although selection is much stronger on the LSu. In Flaveria, two positively selected LSu amino acid substitutions, M309I and D149A, distinguish C(4) Rubiscos from the ancestral C(3) species and statistically account for much of the kinetic difference between the two groups. However, although Flaveria lacks a characteristic "C(4)" SSu, our data suggest that specific residue substitutions in the SSu are correlated with the kinetic properties of Rubisco in this genus.
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| 49. |
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| 50. |
- Liew, Josefine, et al.
(författare)
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Influence of temperature and photoperiod on sprouting capacity of Cirsium arvense and Sonchus arvensis root buds
- 2012
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Ingår i: Weed research (Print). - : Wiley. - 0043-1737 .- 1365-3180. ; 52:5, s. 449-457
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Tidskriftsartikel (refereegranskat)abstract
- Influence of temperature and photoperiod on sprouting capacity of Cirsium arvense and Sonchus arvensis root buds. Weed Research.52, 449-457. Summary Timing of treatment is a key to successful and sustainable weed management. For perennial weeds, highly energy-demanding, repeated stubble cultivation or tillage is a common strategy in organic agriculture. The fragmentation of underground material stimulates root buds to grow and, if repeated, significantly reduces the energy and nutrient resources of the roots. However, the effect might differ depending on variation in sprouting over the season and among species. Here, we studied the impact of different photoperiods and temperatures on sprouting capacity of root buds of Cirsium arvense and Sonchus arvensis in a climate chamber experiment. Two populations of each species, collected in northern and southern Sweden, were used. Plants were exposed to long (18 h), short (12 h) or decreasing (from 18 to 8 h) photoperiods in combinations with high (18/12 degrees C for 16/8 h), low (12/6 degrees C), decreasing (from 21 to 5 degrees C in 4 weeks) or constant high (16 degrees C) temperatures. Sprouting capacity was evaluated based on the proportion of sprouting buds from short root fragments. Neither temperature nor photoperiod affected root bud sprouting in C. arvense, while in S. arvensis, photoperiod seemed to regulate sprouting capacity. The proportion of sprouted buds decreased in short photoperiods, especially if combined with high temperature. In northern conditions, this suggests that weeding strategies based on fragmentation of the root system of S. arvensis will have low efficiency if the autumns are warm.
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