| 1. |
- de Rojas, I., et al.
(författare)
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Common variants in Alzheimer’s disease and risk stratification by polygenic risk scores
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Genetic discoveries of Alzheimer’s disease are the drivers of our understanding, and together with polygenetic risk stratification can contribute towards planning of feasible and efficient preventive and curative clinical trials. We first perform a large genetic association study by merging all available case-control datasets and by-proxy study results (discovery n = 409,435 and validation size n = 58,190). Here, we add six variants associated with Alzheimer’s disease risk (near APP, CHRNE, PRKD3/NDUFAF7, PLCG2 and two exonic variants in the SHARPIN gene). Assessment of the polygenic risk score and stratifying by APOE reveal a 4 to 5.5 years difference in median age at onset of Alzheimer’s disease patients in APOE ɛ4 carriers. Because of this study, the underlying mechanisms of APP can be studied to refine the amyloid cascade and the polygenic risk score provides a tool to select individuals at high risk of Alzheimer’s disease. © 2021, The Author(s).
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| 2. |
- Giang, Kok Wai, 1984, et al.
(författare)
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The risk of dementia after coronary artery bypass grafting in relation to age and sex
- 2021
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 17:6, s. 1042-1050
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Tidskriftsartikel (refereegranskat)abstract
- Introduction We examined the long-term risk of dementia after coronary artery bypass grafting (CABG) in relation to age and sex. Methods All CABG patients in Sweden 1992-2015 (n = 111,335), and matched controls (n = 222,396) were included in a population-based study. Adjusted hazard ratios (aHR) for all-cause dementia, vascular dementia, and Alzheimer's disease were calculated. Results There was no difference in the risk for all-cause dementia between CABG patients and control subjects (aHR 0.98 [95% confidence interval 0.95 to 1.02]). CABG patients <65 years and 65 to 74 years had higher risk (aHR 1.29 [1.17-1.42] and 1.08 [1.02-1.13], respectively), and patients >= 75 years had lower risk (aHR 0.76 [0.71-0.81]). The highest risk was observed in women <65 years (aHR 1.64 [1.31-2.05]). Discussion Overall, the long-term risk for all-cause dementia does not differ between CABG patients and the general population. Younger patients have a higher risk, while older patients have a lower risk, compared to controls.
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| 3. |
- Davies, G., et al.
(författare)
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Study of 300,486 individuals identifies 148 independent genetic loci influencing general cognitive function
- 2018
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- General cognitive function is a prominent and relatively stable human trait that is associated with many important life outcomes. We combine cognitive and genetic data from the CHARGE and COGENT consortia, and UK Biobank (total N = 300,486; age 16-102) and find 148 genome-wide significant independent loci (P < 5 × 10-8) associated with general cognitive function. Within the novel genetic loci are variants associated with neurodegenerative and neurodevelopmental disorders, physical and psychiatric illnesses, and brain structure. Gene-based analyses find 709 genes associated with general cognitive function. Expression levels across the cortex are associated with general cognitive function. Using polygenic scores, up to 4.3% of variance in general cognitive function is predicted in independent samples. We detect significant genetic overlap between general cognitive function, reaction time, and many health variables including eyesight, hypertension, and longevity. In conclusion we identify novel genetic loci and pathways contributing to the heritability of general cognitive function.
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| 4. |
- Nielsen, Susanne, 1969, et al.
(författare)
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Socioeconomic Factors, Secondary Prevention Medication, and Long-Term Survival After Coronary Artery Bypass Grafting: A Population-Based Cohort Study From the SWEDEHEART Registry.
- 2020
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Ingår i: Journal of the American Heart Association. - 2047-9980. ; 9:5
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Tidskriftsartikel (refereegranskat)abstract
- Background Low income and short education have been found to be independently associated with inferior survival after coronary artery bypass grafting (CABG), whereas the use of secondary prevention medications is associated with improved survival. We investigated whether underusage of secondary prevention medications contributes to the inferior long-term survival in CABG patients with a low income and short education. Methods and Results Patients who underwent CABG in Sweden between 2006 to 2015 and survived at least 6months after discharge (n=28448) were included in a population-based cohort study. Individual patient data from 5 national registries, including the SWEDEHEART (Swedish Web System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies) registry, covering dispensing of secondary prevention medications (statins, platelet inhibitors, β-blockers, and RAAS inhibitors), socioeconomic factors, patient characteristics, comorbidity, and long-term mortaity were merged. All-cause mortality risk was estimated using multivariable Cox regression models adjusted for patient characteristics, baseline comorbidities, time-updated secondary prevention medications, and socioeconomic status. Long-term mortality was higher in patients with a low income and short education. Statins and platelet inhibitors were dispensed less often to patients with a low income, both at baseline and after 8years. The decline in dispensing over time was steeper for low-income patients. Short education was not associated with reduced dispensing of any secondary prevention medication. Use of statins (adjusted hazard ratio=0.57 [95% CI, 0.53-0.61]), RAAS inhibitors (adjusted hazard ratio=0.78 [0.73-0.84]), and platelet inhibitors (adjusted hazard ratio=0.74 [0.68-0.80]) were associated with reduced long-term mortality irrespective of socioeconomic status. Conclusions Secondary prevention medications are dispensed less often after CABG to patients with low income. Underusage of secondary prevention medications after CABG is associated with increased mortality risk independently of income and extent of education.
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| 5. |
- Silverborn, Martin, 1969, et al.
(författare)
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The performance of EuroSCORE II in CABG patients in relation to sex, age, and surgical risk: a nationwide study in 14,118 patients
- 2023
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Ingår i: Journal of Cardiothoracic Surgery. - : Springer Science and Business Media LLC. - 1749-8090. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundTo determine the discriminative accuracy and calibration of EuroSCORE II in relation to age, sex, and surgical risk in a large nationwide coronary artery bypass grafting (CABG) cohort.MethodsAll 14,118 patients undergoing isolated CABG in Sweden during 2012-2017 were included. Individual patient data were taken from the SWEDEHEART registry. Patients were divided by age (< 60, 60-69, 70-79, >= 80 years), sex, and surgical risk (low: EuroSCORE < 4%, intermediate: 4-8%, high: > 8%). Discriminative accuracy was determined by the area under the receiver operating characteristic curve (AUC) and calibration by the observed/estimated (O/E) mortality ratio at 30 days.ResultsAUC and O/E ratio were 0.82 (95% CI 0.79-0.85) and 0.58 (0.50-0.66) overall, 0.82 (0.79-0.86) and 0.57 (0.48-0.66) in men, and 0.79 (0.73-0.85) and 0.60 (0.47-0.75) in women. Regarding age, discriminative accuracy was highest in patients aged 60-69 years (AUC: 0.86 [0.80-0.93]) but was satisfactory in all groups (AUC: 0.74-0.80). O/E ratio varied from 0.26 for patients > 60 years to 0.90 for patients > 80 years. Regarding surgical risk, AUC and O/E ratio were 0.63 (0.44-0.83) and 0.18 (0.09-0.30) in low-risk patients, 0.60 (0.55-0.66) and 0.57 (0.46-0.68) in intermediate-risk patients, and 0.78 (0.73-0.83) and 0.78 (0.64-0.92) in high-risk patients.ConclusionsEuroSCORE II had good discriminative accuracy independently of sex and age, but markedly overestimated mortality risk, especially in younger patients. Accuracy and calibration were better in high-risk patients than in low-risk and intermediate-risk patients.
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| 6. |
- Aljassim, Obaid, et al.
(författare)
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Inflammatory response and platelet activation after off-pump coronary artery bypass surgery.
- 2006
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Ingår i: Scandinavian cardiovascular journal : SCJ. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 40:1, s. 43-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cardiac surgery induces a systemic inflammatory activation and alterations in the hemostatic cascade. The responses contribute to postoperative complications but may also have protective effects. We investigated the relationship between inflammation, hemostasis and bleeding after off-pump coronary artery bypass surgery (OPCAB). METHODS: Ten OPCAB patients were included in a prospective descriptive study. Selected markers of inflammation (IL-6, IL-8, PMN-elastase, C3a, and SC5b-9), and hemostasis (platelet count, ss-thromboglobulin, anti-thrombin, D-dimer and fibrinogen) were measured before and immediately after surgery. Postoperative bleeding was registered. RESULTS: Inflammatory variables did not alter significantly during surgery while ss-thromboglobulin concentrations increased and anti-thrombin and fibrinogen decreased. There were significant postoperative correlations between PMN-elastase and ss-thromboglobulin (r=0.82, p=0.004), between PMN-elastase and fibrinogen (r=0.69, p=0.03) and between C3a and ss-thromboglobulin (r=0.71, p=0.02). In addition, there were significant inverse correlations between postoperative bleeding and pre- and postoperative fibrinogen levels (r=-0.76, p=0.011 and r=-0.84, p=0.002 respectively), between bleeding and postoperative ss-thromboglobulin levels (r=-0.66, p=0.04) and between bleeding and postoperative PMN-elastase (r=-0.75, p=0.01). CONCLUSIONS: The results give further evidence for an association between the inflammatory response and hemostasis after cardiac surgery.
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| 7. |
- Ameur, Adam, et al.
(författare)
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SweGen : a whole-genome data resource of genetic variability in a cross-section of the Swedish population
- 2017
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Ingår i: European Journal of Human Genetics. - : NATURE PUBLISHING GROUP. - 1018-4813 .- 1476-5438. ; 25:11, s. 1253-1260
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Tidskriftsartikel (refereegranskat)abstract
- Here we describe the SweGen data set, a comprehensive map of genetic variation in the Swedish population. These data represent a basic resource for clinical genetics laboratories as well as for sequencing-based association studies by providing information on genetic variant frequencies in a cohort that is well matched to national patient cohorts. To select samples for this study, we first examined the genetic structure of the Swedish population using high-density SNP-array data from a nation-wide cohort of over 10 000 Swedish-born individuals included in the Swedish Twin Registry. A total of 1000 individuals, reflecting a cross-section of the population and capturing the main genetic structure, were selected for whole-genome sequencing. Analysis pipelines were developed for automated alignment, variant calling and quality control of the sequencing data. This resulted in a genome-wide collection of aggregated variant frequencies in the Swedish population that we have made available to the scientific community through the website https://swefreq.nbis.se. A total of 29.2 million single-nucleotide variants and 3.8 million indels were detected in the 1000 samples, with 9.9 million of these variants not present in current databases. Each sample contributed with an average of 7199 individual-specific variants. In addition, an average of 8645 larger structural variants (SVs) were detected per individual, and we demonstrate that the population frequencies of these SVs can be used for efficient filtering analyses. Finally, our results show that the genetic diversity within Sweden is substantial compared with the diversity among continental European populations, underscoring the relevance of establishing a local reference data set.
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| 8. |
- Björklund, Erik, et al.
(författare)
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Secondary prevention medications after coronary artery bypass grafting and long-term survival : a population-based longitudinal study from the SWEDEHEART registry.
- 2019
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Ingår i: European Heart Journal. - : Oxford University Press. - 0195-668X .- 1522-9645. ; 41:17, s. 1653-1661
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To evaluate the long-term use of secondary prevention medications [statins, β-blockers, renin-angiotensin-aldosterone system (RAAS) inhibitors, and platelet inhibitors] after coronary artery bypass grafting (CABG) and the association between medication use and mortality.METHODS AND RESULTS: All patients who underwent isolated CABG in Sweden from 2006 to 2015 and survived at least 6 months after discharge were included (n = 28 812). Individual patient data from SWEDEHEART and other mandatory nationwide registries were merged. Multivariable Cox regression models using time-updated data on dispensed prescriptions were used to assess associations between medication use and long-term mortality. Statins were dispensed to 93.9% of the patients 6 months after discharge and to 77.3% 8 years later. Corresponding figures for β-blockers were 91.0% and 76.4%, for RAAS inhibitors 72.9% and 65.9%, and for platelet inhibitors 93.0% and 79.8%. All medications were dispensed less often to patients ≥75 years. Treatment with statins [hazard ratio (HR) 0.56, 95% confidence interval (95% CI) 0.52-0.60], RAAS inhibitors (HR 0.78, 95% CI 0.73-0.84), and platelet inhibitors (HR 0.74, 95% CI 0.69-0.81) were individually associated with lower mortality risk after adjustment for age, gender, comorbidities, and use of other secondary preventive drugs (all P < 0.001). There was no association between β-blockers and mortality risk (HR 0.97, 95% CI 0.90-1.06; P = 0.54).CONCLUSION: The use of secondary prevention medications after CABG was high early after surgery but decreased significantly over time. The results of this observational study, with inherent risk of selection bias, suggest that treatment with statins, RAAS inhibitors, and platelet inhibitors is essential after CABG whereas the routine use of β-blockers may be questioned.
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| 9. |
- Cooney, Martin, 1980-, et al.
(författare)
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Impressions of Size-Changing in a Companion Robot
- 2015
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Ingår i: PhyCS 2015 – 2nd International Conference on Physiological Computing Systems, Proceedings. - : SciTePress. - 9789897580857 ; , s. 118-123
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Konferensbidrag (refereegranskat)abstract
- Physiological data such as head movements can be used to intuitively control a companion robot to perform useful tasks. We believe that some tasks such as reaching for high objects or getting out of a person’s way could be accomplished via size changes, but such motions should not seem threatening or bothersome. To gain insight into how size changes are perceived, the Think Aloud Method was used to gather typical impressions of a new robotic prototype which can expand in height or width based on a user’s head movements. The results indicate promise for such systems, also highlighting some potential pitfalls.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Hirlekar, Geir, et al.
(författare)
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Comorbidity and bystander cardiopulmonary resuscitation in out-of-hospital cardiac arrest.
- 2020
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Ingår i: Heart. - : BMJ. - 1355-6037 .- 1468-201X. ; 106:14, s. 1087-1093
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Cardiopulmonary resuscitation (CPR) performed before the arrival of emergency medical services (EMS) is associated with increased survival after out-of-hospital cardiac arrest (OHCA). The aim of this study was to determine whether patients who receive bystander CPR have a different comorbidity compared with patients who do not, and to determine the association between bystander CPR and 30-day survival when adjusting for such a possible difference. METHODS: Patients with witnessed OHCA in the Swedish Registry for Cardiopulmonary Resuscitation between 2011 and 2015 were included, and merged with the National Patient Registry. The Charlson Comorbidity Index (CCI) was used to measure comorbidity. Multiple logistic regression was used to examine the effect of CCI on the association between bystander CPR and outcome. RESULTS: In total, 11 955 patients with OHCA were included, 71% of whom received bystander CPR. Patients who received bystander CPR had somewhat lower comorbidity (CCI) than those who did not (mean±SD: 2.2±2.3 vs 2.5±2.4; p<0.0001). However, this difference in comorbidity had no influence on the association between bystander CPR and 30-day survival in a multivariable model including other possible confounders (OR 2.34 (95% CI 2.01 to 2.74) without adjustment for CCI and OR 2.32 (95% CI 1.98 to 2.71) with adjustment for CCI). CONCLUSION: Patients who undergo CPR before the arrival of EMS have a somewhat lower degree of comorbidity than those who do not. Taking this difference into account, bystander CPR is still associated with a marked increase in 30-day survival after OHCA.
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| 14. |
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| 15. |
- Karlsson, Ida, 1980, et al.
(författare)
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Achieving net-zero carbon emissions in construction supply chains - A multidimensional analysis of residential building systems
- 2021
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Ingår i: Developments in the Built Environment. - : Elsevier BV. - 2666-1659. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The construction sector accounts for approximately 25% of global CO2 emissions. In this paper, we provide a multidimensional assessment of the potential for greenhouse gas emissions abatement in relation to the construction of multi-family residential buildings. Different building designs are compared, whereby the study analyzes the potential reductions in greenhouse gas emissions when combining abatement measures with a perspective of the technologies and practices available now, and those that are likely to become available on a timescale up to Year 2045. Further, the assessment analyzes the potential for emissions reductions when applying abatement measures at different points in the supply chain, from primary material production via material composition to the final building structure. The results indicate that the greenhouse gas emissions can be reduced by up to 40% with currently available technologies and practices, with even greater potential reductions of 80% to Year 2030 and 93% to Year 2045.
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| 16. |
- Karlsson, Johan, 1984, et al.
(författare)
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Localized controlled drug delivery from mesoporous implants
- 2014
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Ingår i: Technical Proceedings of the 2014 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2014. Washington, DC, United States, 15-18 June 2014. - 9781482258271
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Konferensbidrag (refereegranskat)abstract
- Mesoporous materials possess both a well-defined topography on the nanometer scale, and they may serve as hosts for drugs. In this work, titanium implants coated with mesoporous TiO2 thin films have been evaluated both in vitro and in vivo. Material characterization showed that, long-range ordered mesoporous TiO2, with a pore-size of 6 nm, and a narrow pore-size distribution were obtained. An in vivo study demonstrated that the films were robust enough to withstand the implantation procedure. The in vitro apatite formation experiments showed that formation of apatite was higher on the mesoporous surface compared to its nonporous counterpart. In a separate in vivo study, two osteoporosis drugs, alendronate (ALN) and raloxifene (RLX), were immobilised into the nanoporous oxide films. The in vitro drug release tests carried out showed a sustained release of both drugs. The osteogenic response after 28 days of implantation of the drug-loaded implants showed a significantly improved bone fixation.
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| 17. |
- Karlsson, Johan, 1984, et al.
(författare)
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The effect of alendronate on biomineralization at the bone/implant interface
- 2016
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Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 104:3, s. 620-629
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Tidskriftsartikel (refereegranskat)abstract
- A recent approach to improve the osseointegration of implants is to utilize local drug administration. The presence of an osteoporosis drug may influence both bone quantity and quality at the bone/implant interface. Despite this, the performance of bone-anchoring implants is traditionally evaluated only by quantitative measurements. In the present study, the osteoporosis drug alendronate (ALN) was administrated from mesoporous titania thin films that were coated onto titanium implants. The effect that the drug had on biomineralization was explored both in vitro using simulated body fluid (SBF) and in vivo in a rat tibia model. The SBF study showed that the apatite formation was completely hindered at a high concentration of ALN (0.1 mg/mL). However, when ALN was administrated from the mesoporous coating the surface became completely covered with apatite. Ex vivo characterization of the bone/implant interface using Raman spectroscopy demonstrated that the presence of ALN enhanced the bone mineralization, and that the chemical signature of newly formed bone in the presence of ALN had a higher resemblance to the pre-existing mature bone than to the bone formed without drug. Taken together, this study demonstrates the importance of evaluating the quality of the formed bone to better understand the performance of implants.
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| 18. |
- Karlsson, Johan, et al.
(författare)
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The effect of alendronate on biomineralization at the bone/implant interface.
- 2016
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Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 104:3, s. 620-629
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Tidskriftsartikel (refereegranskat)abstract
- A recent approach to improve the osseointegration of implants is to utilize local drug administration. The presence of an osteoporosis drug may influence both bone quantity and quality at the bone/implant interface. Despite this, the performance of bone-anchoring implants is traditionally evaluated only by quantitative measurements. In the present study, the osteoporosis drug alendronate (ALN) was administrated from mesoporous titania thin films that were coated onto titanium implants. The effect that the drug had on biomineralization was explored both in vitro using simulated body fluid (SBF) and in vivo in a rat tibia model. The SBF study showed that the apatite formation was completely hindered at a high concentration of ALN (0.1 mg/mL). However, when ALN was administrated from the mesoporous coating the surface became completely covered with apatite. Ex vivo characterization of the bone/implant interface using Raman spectroscopy demonstrated that the presence of ALN enhanced the bone mineralization, and that the chemical signature of newly formed bone in the presence of ALN had a higher resemblance to the pre-existing mature bone than to the bone formed without drug. Taken together, this study demonstrates the importance of evaluating the quality of the formed bone to better understand the performance of implants. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A 104A: 620-629, 2016.
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| 19. |
- Karlsson, Maths, 1978, et al.
(författare)
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Alkali-ion concentration dependence of the structure of proton-conducting alkali thio-hydroxogermanates investigated with neutron diffraction
- 2015
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Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738. ; 274, s. 40-45
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Tidskriftsartikel (refereegranskat)abstract
- The proton-conducting hydrated alkali thio-hydroxogermanate's MxGeSx(OH)(4) - x center dot yH(2)O (M = Na and K; x = 1 - 4,y approximate to 0.5 - 2) were investigated by means of neutron diffraction with the aim to elucidate how the structure changes as a function of alkali-ion concentration, x, type of alkali ion, M, and water content, y. For x = 1 - 3 we find that the materials are amorphous and composed of thio-hydroxogermanate anions, water molecules, and charge balancing alkali ions, whereas for x = 4 we find that the materials contain also a crystalline phase, suggesting that it is difficult to prepare purely amorphous materials for the highest alkali-ion concentration, for both the Na and K based materials. For x = 1 - 3, the structure is reflected by an intermediate-range ordering, with a characteristic length-scale ranging from approximately 6 to 9 angstrom, which is dependent on both x and M and which may be related to the separation distance between dimers of thio-hydroxogermanate anions. As x increases, the intermediate-range ordering shortens, possibly as the result of an increasing level of hydration water that may act as a dielectric medium that reduces the repulsive interaction between the negatively charged thio-hydroxogermanate anions and/or between the positively charged alkali ions. A comparison of the structural results to the reported conductivities of the same materials indicates a non-trivial relationship, which depends on both the type and concentration of alkali ions, as well as on the level of hydration water.
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| 20. |
- Karlsson, Martin, 1978
(författare)
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Fibrinogen and Bleeding in Cardiac Surgery: Clinical Studies in Coronary Artery Bypass Patients
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fibrinogen and Bleeding in Cardiac Surgery: Clinical Studies in Coronary Artery Bypass Patients Background: Cardiac surgery is accompanied by inflammatory activation and bleeding complications. Fibrinogen is a key factor in the coagulation cascade and can be used to treat ongoing bleeding, but is not well studied as prophylactic treatment to prevent bleeding in patients with normal plasma fibrinogen levels or as a predictive tool to identify patients with increased bleeding risk. Aims: To investigate the association between biomarkers of inflammation and hemostasis after off pump coronary artery bypass grafting (OPCAB). Further, to study the relationship between plasma fibrinogen concentration and postoperative bleeding and transfusion after on pump coronary artery bypass grafting (CABG). To investigate if prophylactic fibrinogen infusion reduces bleeding and transfusions after CABG. Finally, to study the effect of fibrinogen infusion on markers of coagulation, fibrinolysis and platelet function. Materials and methods: In study I, biomarkers of inflammation (Il-6, Il-8, PMN-elastase, C3a, sC5b-9) and hemostasis (platelet count, -thromboglobulin, anti-thrombin, D-dimer and fibrinogen) were measured before and after surgery in 10 OPCAB patients. II: plasma fibrinogen was analyzed the day before surgery in 170 elective CABG patients and related to postoperative bleeding and transfusions. III: 20 patients were randomized to preoperative infusion of 2 grams (g) fibrinogen concentrate or placebo. Side effects, bleeding and transfusions were registered. IV: Biomarkers of coagulation, fibrinolysis and platelet activation in relation to fibrinogen treatment were analyzed in the same patients as in study III. Results: I: Inflammatory markers did not change during surgery while -thromboglobulin increased and anti-thrombin and fibrinogen decreased. There were significant correlations between several markers of inflammation and hemostasis. II: Postoperative bleeding volume correlated univariately with preoperative fibrinogen concentration (r = -0.53, p<0.001). Fibrinogen was an independent predictor of postoperative bleeding volume and blood transfusions. III: Infusion of 2g fibrinogen increased plasma levels by 0.6 ± 0.2 g/l and reduced postoperative blood loss by 32%. There were no clinically detectable adverse events of fibrinogen infusion. IV: Fibrinogen infusion induced no or minimal changes in most investigated biomarkers, except D-dimer which was significantly higher 2h after surgery in the fibrinogen group. Conclusions: There is evidence for an association between the inflammatory response and hemostasis after cardiac surgery. The preoperative fibrinogen concentration is a limiting factor for postoperative hemostasis. Preoperative measurement of fibrinogen provides information about bleeding volume and transfusion requirements after CABG. Prophylactic fibrinogen infusion significantly reduces postoperative bleeding without clinical adverse events. Infusion of 2g fibrinogen to cardiac surgery patients results in no or minimal changes in biomarkers reflecting coagulation and platelet function.
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| 21. |
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| 22. |
- Karlsson, Martin, 1978, et al.
(författare)
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Plasma fibrinogen level, bleeding and transfusion after on-pump coronary artery bypass grafting surgery: a prospective observational study
- 2008
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Ingår i: Transfusion. - : Wiley. - 1537-2995 .- 0041-1132. ; 48:10, s. 2152-2158
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Early identification of patients with increased risk of excessive bleeding and transfusion after cardiac surgery offers the possibility to initiate countermeasures. Fibrinogen is a key protein in the coagulation cascade and thus a potential biomarker for bleeding. We investigated the relationship between preoperative fibrinogen plasma concentration and postoperative bleeding and transfusion after coronary artery bypass grafting (CABG). STUDY DESIGN AND METHODS: A total of 170 patients (mean age, 67 ± 9 years; 75% men) undergoing isolated CABG were included in a prospective observational study. Patient variables (age, sex, operation time, anticoagulation therapy), preoperative laboratory variables (platelet [PLT] count, activated partial thromboplastin time, prothrombin time, and fibrinogen), postoperative bleeding volume, and transfusions during hospital stay were registered. Independent predictors of bleeding volume and transfusion were identified with multiple regression models. RESULTS: Postoperative bleeding volume correlated univariately with preoperative fibrinogen concentration (r = −0.53, p < 0.001) and PLT count (r = −0.26, p = 0.001) but only preoperative fibrinogen concentration was an independent predictor of postoperative bleeding volume. Twenty-nine of the 170 patients (17%) received transfusions with blood products. Independent predictors of transfusion were preoperative fibrinogen concentration (odds ratio [OR], 2.0; 95% confidence interval [CI], 1.1-3.7 per 1-unit decrease; p = 0.027), female sex (OR, 5.0; 95% CI, 1.8-14.7; p = 0.002), and aortic cross-clamp time (OR, 1.03; 95% CI, 1.01-1.06 per minute; p = 0.013). CONCLUSION: The results indicate that preoperative fibrinogen concentration (even within the normal range) is a limiting factor for postoperative hemostasis. Preoperative measurement of fibrinogen concentration provides information about bleeding volume and transfusion requirements after CABG.
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| 23. |
- Karlsson, Martin, 1978, et al.
(författare)
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Prophylactic Fibrinogen Infusion in Cardiac Surgery Patients: Effects on Biomarkers of Coagulation, Fibrinolysis, and Platelet Function.
- 2011
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Ingår i: Clinical and applied thrombosis/hemostasis. - : SAGE Publications. - 1938-2723 .- 1076-0296. ; 17:4, s. 393-404
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Tidskriftsartikel (refereegranskat)abstract
- Objective: We have recently reported that prophylactic fibrinogen infusion reduces bleeding after coronary artery bypass grafting (CABG) surgery. Because fibrinogen for the first time was administered to patients without hereditary fibrinogen deficiency or ongoing bleeding, a detailed analysis of the effects of fibrinogen concentrate on biomarkers of coagulation, fibrinolysis, and platelet function was performed. Methods: Twenty CABG patients with preoperative plasma fibrinogen levels <3.8 g/L were included in a prospective study. Patients were randomized to preoperative infusion of 2 g fibrinogen concentrate (fibrinogen group) or no infusion (control group). Activated partial thromboplastin time (aPTT), prothrombin time, activated clotting time, and plasma concentrations of fibrinogen, antithrombin, thrombin-antithrombin complex, prothrombin fragment 1.2, and d-dimer, thromboelastometry, platelet count, and platelet aggregometry were analyzed before and 15 minutes after infusion, and 2 and 24 hours after surgery. Results: Fifteen minutes after infusion of fibrinogen concentrate, fibrinogen plasma levels increased by 0.6 +/- 0.2 g/L (P < .001 between groups), and induced minimal changes in aPTT and plasma levels of antithrombin, while remaining variables remained unchanged. After surgery, fibrinogen levels no longer differed between groups. d-dimer was significantly higher after surgery in the fibrinogen group (P = .03), while none of the other markers were statistically different between groups. Conclusions: Infusion of 2 g fibrinogen to cardiac surgery patients, without hereditary or acquired fibrinogen deficiency or ongoing bleeding, results in no or minimal changes in biomarkers reflecting coagulation and platelet function. An increased release of fibrin degradation products was detected after surgery in fibrinogen-treated patients.
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| 24. |
- Karlsson, Martin, 1978, et al.
(författare)
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Prophylactic fibrinogen infusion reduces bleeding after coronary artery bypass surgery
- 2009
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Ingår i: Thrombosis & Haemostasis. ; 102, s. 137-144
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that preoperative fibrinogen plasma concentration is independently associated to postoperative blood loss after cardiac surgery. Theoretically, prophylactic infusion of fibrinogen concentrate may thus reduce postoperative bleeding, but this has not previously been investigated. Twenty elective coronary artery bypass graft (CABG) patients with preoperative plasma fibrinogen levels <3.8 g/l were included in a prospective randomised pilot study. Patients were randomised to receive an infusion of 2 g fibrinogen concentrate (FIB group) or no infusion before surgery (control group). Primary endpoint was safety with clinical adverse events and graft occlusion assessed by multi-slice computed tomography. Predefined secondary endpoints were postoperative blood loss, blood transfusions, haemoglobin levels 24 hours (h) after surgery, and global haemostasis assessed with thromboelastometry, 2 and 24 hours after surgery. Infusion of 2 g fibrinogen concentrate increased plasma levels of fibrinogen by 0.6 ± 0.2 g/l. There were no clinically detectable adverse events of fibrinogen infusion. Computed tomography revealed one subclinical vein graft occlusion in the FIB group. Fibrinogen concentrate infusion reduced postoperative blood loss by 32% (565 ± 150 vs. 830 ± 268 ml/12 h, p=0.010). Haemoglobin concentration was significantly higher 24 h after surgery in the FIB group(110 ± 12 vs. 98 ± 8 g/l, p=0.018). Prophylactic fibrinogen concentrate infusion did not influence global postoperative haemostasis as assessed by thromboelastometry. In conclusion, in this pilot study preoperative fibrinogen concentrate infusion reduced bleeding after CABG without evidence of postoperative hypercoagulability. Larger studies are necessary to ensure safety and confirm efficacy of prophylactic fibrinogen treatment in cardiac surgery.
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| 25. |
- Karlsson, Martin, 1978, et al.
(författare)
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Sampling Conditions Influence Multiple Electrode Platelet Aggregometry in Cardiac Surgery Patients. : Platelet aggregometry in cardiac surgery
- 2013
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Ingår i: Scandinavian cardiovascular journal : SCJ. - : Informa UK Limited. - 1651-2006 .- 1401-7431. ; 47:2, s. 98-103
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Tidskriftsartikel (refereegranskat)abstract
- ABSTRACT Objectives: To investigate the importance of blood sampling conditions for multiple electrode platelet aggregometry (MEA) in cardiac surgery patients. Design: Eighty-one patients undergoing first time CABG surgery were included in three prospective, observational studies. MEA was used to analyze platelet aggregability after addition of adenosine-diphosphate (ADP) or thrombin activating peptide 6 (TRAP). In substudy 1, hirudin and citrate tubes were compared. In substudy 2, samples from peripheral vein, central venous catheter and radial artery were compared and in substudy 3, the effect of surgery was investigated by analyzing pre- and postoperative samples. Results: Platelet aggregability values were 30% higher in hirudin tubes than in citrate tubes. There was a significant correlation between hirudin and citrate tubes in TRAP-induced aggregability (r=0.84, p<0.001) but not in ADP-induced aggregability (r=0.25, p=0.13). Blood sampling site did not influence platelet aggregability. Surgery reduced ADP-induced aggregability with 31% (p<0.001) and TRAP-induced aggregability with 30 % (p<0.001) with large intraindividual variations. Conclusions: MEA results in cardiac surgery patients should not be compared between samples collected in test tubes with different anticoagulants. The choice of blood sampling site does not affect the results. The operation in itself reduces markedly mean platelet aggregability.
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| 26. |
- Karlsson, Maths, 1978, et al.
(författare)
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Structural Origin of the Mixed Glass Former Effect in Sodium Borophosphate Glasses Investigated with Neutron Diffraction and Reverse Monte Carlo Modeling
- 2015
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 119:49, s. 27275-27284
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Tidskriftsartikel (refereegranskat)abstract
- The mixed glass former systems 0.35Na(2)O + 0.65[xB(2)O(3) + (1 - x)P2O5] and 0.5Na(2)O + 0.5[xB(2)O(3) + (1 - x)P2O5] with x = 0-1 were investigated with neutron diffraction (ND) together with reverse Monte Carlo (RMC) modeling of 0.35Na(2)O + 0.65[xB(2)O(3) + (1 - x)P2O5]. The results show that the structure of both systems is reflected by an intermediate-range ordering, with a characteristic x-dependent length scale of about 4-6 angstrom and which contracts slightly with the increase of the Na concentration. Results obtained from RMC modeling of the 0.35Na(2)O + 0.65[xB(2)O(3) + (1 - x)P2O5] system, using both previously reported X-ray diffraction (XRD) data as well as the here obtained ND data as independent constraints in the modeling, show that the intermediate-range structural features, notably the Na coordination and volume fraction of the conducting pathways, are only weakly dependent on the choice of the constraints used. In particular, we observe that the volume fraction of the conducting pathways and the activation energy for ionic conduction are only weakly correlated to each other, as opposed to what is found for binary alkali borate and phosphate glasses.
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| 27. |
- Karlsson, Maths, 1978, et al.
(författare)
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Structure of Proton-Conducting Alkali Thio-Hydroxogermanates
- 2008
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 1520-5002 .- 0897-4756. ; 20:19, s. 6014-6021
-
Tidskriftsartikel (refereegranskat)abstract
- Using a combination of neutron diffraction, infrared spectroscopy, and first-principles calculations, we have investigated the structure of hydrated and dehydrated proton conducting alkali thio-hydroxogermanates of general formula M2GeS2(OH)2·yH2O (M = K, Rb, and Cs). The results show that the structure of hydrated and dry materials are basically the same, which confirms previous indications that the main effect of heating these materials is just a loss of water. We suggest that in the hydrated state the structure of these materials is built of dimers of thio-hydroxogermanate anions, with the water molecules acting as bridges between such dimers. In the dehydrated structure, the thio-hydroxogermanate anions instead form an extended network through the formation of interdimer hydrogen bonds through the −OH groups in the structure. The alkali ions are suggested to act as “space-fillers” in voids formed by the thio-hydroxogermanate anion dimers, in both the hydrated and the dehydrated state.
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| 28. |
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| 29. |
- Karlsson, Therese, 1987, et al.
(författare)
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Comparison between manta trawl and in situ pump filtration methods, and guidance for visual identification of microplastics in surface waters
- 2020
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 27:5, s. 5559-5571
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Tidskriftsartikel (refereegranskat)abstract
- Owing to the development and adoption of a variety of methods for sampling and identifying microplastics, there is now data showing the presence of microplastics in surface waters from all over the world. The difference between the methods, however, hampers comparisons, and to date, most studies are qualitative rather than quantitative. In order to allow for a quantitative comparison of microplastics abundance, it is crucial to understand the differences between sampling methods. Therefore, a manta trawl and an in situ filtering pump were compared during realistic, but controlled, field tests. Identical microplastic analyses of all replicates allowed the differences between the methods with respect to (1) precision, (2) concentrations, and (3) composition to be assessed. The results show that the pump gave higher accuracy with respect to volume than the trawl. The trawl, however, sampled higher concentrations, which appeared to be due to a more efficient sampling of particles on the sea surface microlayer, such as expanded polystyrene and air-filled microspheres. The trawl also sampled a higher volume, which decreased statistical counting uncertainties. A key finding in this study was that, regardless of sampling method, it is critical that a sufficiently high volume is sampled to provide enough particles for statistical evaluation. Due to the patchiness of this type of contaminant, our data indicate that a minimum of 26 particles per sample should be recorded to allow for concentration comparisons and to avoid false null values. The necessary amount of replicates to detect temporal or spatial differences is also discussed. For compositional differences and size distributions, even higher particle counts would be necessary. Quantitative measurements and comparisons would also require an unbiased approach towards both visual and spectroscopic identification. To facilitate the development of such methods, a visual protocol that can be further developed to fit different needs is introduced and discussed. Some of the challenges encountered while using FTIR microspectroscopic particle identification are also critically discussed in relation to specific compositions found.
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| 30. |
- Karlsson, Therese, et al.
(författare)
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Provtagningsmetoder för mikroplast >300 μm i ytvatten : En jämförelsestudie mellan pump och trål
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Mikroplast (MP) är en föroreningstyp som medför stora utmaningar för provtagning och analys. För att kunna förbättra framtida miljöövervakning så jämfördes här två vanliga metoder för provtagning av mikroplast >300 μm; mantatrål och pump. Sex provreplikat för vardera metod togs under vindstilla förhållanden på ett och samma område under en dag. Provtagningsvolymen för varje replikat var 20 m3 för pumpen och ca 60 m3 för trålen. Efterföljande analys gjordes med visuell bedömning av en och samma person där antropogena partiklar delades in i elva kategorier.I pumpproverna hittades mellan 0 och 8 MPs som i volym räknat gav ett medelvärde av 0,17 MP/m3. I trålproverna varierade antalet mellan 9 och 33 MP som i volym räknat gav en signifikant högre koncentration än i trålproverna med ett medelvärde av 0,32 MP/m3. Resultaten innebar även att för att uppnå en statistisk power på 60 % så skulle tio pumpreplikat behövas för att mäta skillnaden mellan det undersökta området och ett område utan mikroplast. För trålen skulle motsvarande kräva 2 replikat. Alternativt kan en större provvolym ge en ökad säkerhet i och med att fördelningsdata då närmar sig en normalfördelning. Variationerna i mätosäkerhet mellan metoderna bedöms framförallt vara relaterad till skillnad i provvolym och skulle också kunna kompenseras genom ökad pumpvolym, vilket skulle gå något snabbare jämfört med att göra fler replikat.Sammansättningen av MP varierade en del mellan replikaten men bestod främst av expanderad cellplast, filmer, filament, och fragment. I vartdera pumpprov var det i genomsnitt 1,3 filmer och 0,33 expanderade cellplastpartiklar medan trålen hade i genomsnitt 2,5 filmer och 9,2 expanderade cellplastpartiklar. Per volymenhet utgjorde filmer den största delen av MP i prover tagna med pump (40 %), medan cellplast dominerade i trålproverna (46 %). Cellplast tycks därmed provtas mer effektivt med trål vilket kan bero på att den flyter på det översta ytlagret som trålen provtar. Pumpen ligger något lägre i ytskiktet och jämförelsestudien indikerar att de båda provtagarna har en mer jämförbar provsammansättning för partiklar med en mer neutral flytkraft. I denna studie erhölls dock inte tillräckligt stort antal partiklar av olika plasttyper för att tillåta mer ingående statistiska jämförelser mellan provsammansättningarna.Sannolikheten för att få falska nollvärden ökar vid lägre partikelantal vilket börjar få en signifikant effekt under 5 partiklar per prov. Oavsett vilken metod som används är det viktigt att tillräckligt stor volym provtas för att besvara frågeställningar som skillnader mellan olika områden och skillnader mellan olika sorters plast.Bakgrund och syfte med rapportenÄven om metoder för provtagning, extraktion och identifikation av mikroplast har utvecklats snabbt under senare år så återstår ännu flera utmaningar. Flertalet studier publicerar förekomst av mikroplast i sjöar och hav. En av de utmaningarna består i hur vi på ett representativt sätt ska kunna provta en förorening som är så pass heterogen, både till form och också utbredning. En annan frågeställning är huruvida det går att jämföra resultat från två olika provtagningsmetoder. Här jämför vi två metoder som ofta används för att provta mikroplast med storlek över 300 μm i ytvatten; en mantatrål och en pump. Under en dag (10 oktober 2017) togs 6 replikat per metod på samma plats i Gullmarsfjorden utanför Lysekil. Genom att räkna mikroplast och annat mikroskräp i proverna var syftet att undersöka skillnader mellan replikat och skillnader mellan metoderna.Jämförelsen har gjorts på uppdrag av Naturvårdsverket och Havs- och vattenmyndigheten som ett led i arbetet med att utveckla övervakning av mikroskräp.
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| 31. |
- Klang, Nina, 1978-, et al.
(författare)
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Mathematical Problem-Solving Through Cooperative Learning-The Importance of Peer Acceptance and Friendships
- 2021
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Ingår i: Frontiers in Education. - : Frontiers Media SA. - 2504-284X. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Mathematical problem-solving constitutes an important area of mathematics instruction, and there is a need for research on instructional approaches supporting student learning in this area. This study aims to contribute to previous research by studying the effects of an instructional approach of cooperative learning on students' mathematical problem-solving in heterogeneous classrooms in grade five, in which students with special needs are educated alongside with their peers. The intervention combined a cooperative learning approach with instruction in problem-solving strategies including mathematical models of multiplication/division, proportionality, and geometry. The teachers in the experimental group received training in cooperative learning and mathematical problem-solving, and implemented the intervention for 15 weeks. The teachers in the control group received training in mathematical problem-solving and provided instruction as they would usually. Students (269 in the intervention and 312 in the control group) participated in tests of mathematical problem-solving in the areas of multiplication/division, proportionality, and geometry before and after the intervention. The results revealed significant effects of the intervention on student performance in overall problem-solving and problem-solving in geometry. The students who received higher scores on social acceptance and friendships for the pre-test also received higher scores on the selected tests of mathematical problem-solving. Thus, the cooperative learning approach may lead to gains in mathematical problem-solving in heterogeneous classrooms, but social acceptance and friendships may also greatly impact students' results.
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| 32. |
- Lindfors, Martin, 1990-, et al.
(författare)
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Freqeuncy Tracking of Wheel Vibrations
- 2021
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Ingår i: IEEE Transactions on Control Systems Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 1063-6536 .- 1558-0865. ; 29:3, s. 1304-1309
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Tidskriftsartikel (refereegranskat)abstract
- The angular wheel speed of a vehicle is estimated by tracking the frequency of chassis vibrations measured with an accelerometer. A Bayesian filtering framework is proposed, allowing for straightforward incorporation of supporting information. The framework is evaluated on a large number of experimental test drives, showing comparable performance to the standard periodogram method. We then demonstrate the flexibility of the framework using accelerometer information in two ways, combining the high-frequency vibrations with low-frequency information about the vehicle acceleration. This is shown to improve robustness and resolve many cases where stand-alone frequency tracking fails.
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| 33. |
- Lindfors, Martin, 1990-
(författare)
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Frequency Tracking for Speed Estimation
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Estimating the frequency of a periodic signal, or tracking the time-varying frequency of an almost periodic signal, is an important problem that is well studied in literature. This thesis focuses on two subproblems where contributions can be made to the existing theory: frequency tracking methods and measurements containing outliers.Maximum-likelihood-based frequency estimation methods are studied, focusing on methods which can handle outliers in the measurements. Katkovnik’s frequency estimation method is generalized to real and harmonic signals, and a new method based on expectation-maximization is proposed. The methods are compared in a simulation study in which the measurements contain outliers. The proposed methods are compared with the standard periodogram method.Recursive Bayesian methods for frequency tracking are studied, focusing on the Rao-Blackwellized point mass filter (RBPMF). Two reformulations of the RBPMF aiming to reduce computational costs are proposed. Furthermore, the technique of variational approximate Rao-Blackwellization is proposed, which allows usage of a Student’s t distributed measurement noise model. This enables recursive frequency tracking methods to handle outliers using heavy-tailed noise models in Rao-Blackwellized filters such as the RBPMF. A simulation study illustrates the performance of the methods when outliers occur in the measurement noise.The framework above is applied to and studied in detail in two applications. The first application is on frequency tracking of engine sound. Microphone measurements are used to track the frequency of Doppler-shifted variants of the engine sound of a vehicle moving through an area. These estimates can be used to compute the speed of the vehicle. Periodogram-based methods and the RBPMF are evaluated on simulated and experimental data. The results indicate that the RBPMF has lower rmse than periodogram-based methods when tracking fast changes in the frequency.The second application relates to frequency tracking of wheel vibrations, where a car has been equipped with an accelerometer. The accelerometer measurements are used to track the frequency of the wheel axle vibrations, which relates to the wheel rotational speed. The velocity of the vehicle can then be estimated without any other sensors and without requiring integration of the accelerometer measurements. In situations with high signal-to-noise ratio (SNR), the methods perform well. To remedy situations when the methods perform poorly, an accelerometer input is introduced to the formulation. This input is used to predict changes in the frequency for short time intervals.
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| 34. |
- Lindfors, Martin, 1990-, et al.
(författare)
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On Frequency Tracking in Harmonic Acoustic Signals
- 2017
-
Ingår i: Proceedings of the 2017 20th International Conference on Information Fusion (FUSION).. - : IEEE. - 9780996452700 - 9781509045822
-
Konferensbidrag (refereegranskat)abstract
- Acoustic frequency tracking of a harmonic signalwith continuously varying frequency is considered. The Rao-Blackwellized point mass filter (RBPMF), previously proposed bythe authors for mechanical vibration tracking, is applied to the problem. The RBPMF is compared with two periodogram-based methods, and the similarities and differences between them are explained. Both experimental and simulation results in a Doppler frequency tracking scenario are presented, and the results show that the RBPMF can have significantly less estimation error than the competing methods.
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| 35. |
- Lindfors, Martin, 1990-, et al.
(författare)
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Vehicle Speed Tracking Using Chassis Vibrations
- 2016
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Ingår i: Proceedings of the 2016 IEEE Intelligent Vehicles Symposium (IV). - : IEEE conference proceedings. - 9781509018215 ; , s. 214-219
-
Konferensbidrag (refereegranskat)abstract
- The speed of a wheeled vehicle is usually estimatedusing wheel speed sensors (WSS) or GPS. If these signals are unavailable, other methods must be used. We propose a novelapproach exploiting the fact that vibrations from rotating axles,with fundamental frequency proportional to vehicle speed, aretransmitted via the vehicle chassis. Using an accelerometer, these vibrations can be tracked to estimate vehicle speed whileother sources of vibrations act as disturbances. A state-space model for the dynamics of the harmonics is presented andformulated such that there is a conditional linear-Gaussiansubstructure, enabling efficient Rao-Blackwellized methods. Avariant of the Rao-Blackwellized point-mass filter is derived, significantly reducing computational complexity, and reducingthe memory requirements from quadratic to linear in thenumber of grid points. It is applied to experimental data from the sensor cluster of a car and validated using therotational frequency from WSS data. The proposed methodshows improved performance and robustness in comparisonto a Rao-Blackwellized particle filter implementation and afrequency spectrum maximization method.
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| 36. |
- Längkvist, Martin, 1983-, et al.
(författare)
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A review of unsupervised feature learning and deep learning for time-series modeling
- 2014
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Ingår i: Pattern Recognition Letters. - : Elsevier. - 0167-8655 .- 1872-7344. ; 42:1, s. 11-24
-
Forskningsöversikt (refereegranskat)abstract
- This paper gives a review of the recent developments in deep learning and unsupervised feature learning for time-series problems. While these techniques have shown promise for modeling static data, such as computer vision, applying them to time-series data is gaining increasing attention. This paper overviews the particular challenges present in time-series data and provides a review of the works that have either applied time-series data to unsupervised feature learning algorithms or alternatively have contributed to modifications of feature learning algorithms to take into account the challenges present in time-series data.
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| 37. |
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| 38. |
- Längkvist, Martin, 1983-, et al.
(författare)
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Sleep stage classification using unsupervised feature learning
- 2012
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Ingår i: Advances in Artificial Neural Systems. - : Hindawi Publishing Corporation. - 1687-7594 .- 1687-7608. ; , s. 107046-
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Tidskriftsartikel (refereegranskat)abstract
- Most attempts at training computers for the difficult and time-consuming task of sleep stage classification involve a feature extraction step. Due to the complexity of multimodal sleep data, the size of the feature space can grow to the extent that it is also necessary to include a feature selection step. In this paper, we propose the use of an unsupervised feature learning architecture called deep belief nets (DBNs) and show how to apply it to sleep data in order to eliminate the use of handmade features. Using a postprocessing step of hidden Markov model (HMM) to accurately capture sleep stage switching, we compare our results to a feature-based approach. A study of anomaly detection with the application to home environment data collection is also presented. The results using raw data with a deep architecture, such as the DBN, were comparable to a feature-based approach when validated on clinical datasets.
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| 39. |
- Naumovska, Elena, et al.
(författare)
-
Local structure of hydrated nanocrystalline films of the proton conductor BaZr 1-x Sc x O 3-x/2 studied by infrared spectroscopy
- 2024
-
Ingår i: Vibrational Spectroscopy. - 0924-2031. ; 130
-
Tidskriftsartikel (refereegranskat)abstract
- We report results from a study of the local structure of hydrated nanocrystalline 2 μm films of the well known proton conductor BaZr1-xScxO3-x/2 with x = 0.45, 0.54 and 0.64, using infrared (IR) spectroscopy. The films were prepared by magnetron sputtering. Analysis of the IR spectra focused on the O–H stretching region (2000—3700 cm-1), which reveals the presence of several distinct O–H stretching bands for which the intensity and frequency of each band vary in an unsystematic manner with Sc concentration. The spectra for the two higher Sc concentrations, x = 0.54 and 0.64, exhibit a distinct, highly intense O–H stretching band centered at around 3400–3500 cm-1, which is assigned to relatively symmetric, weakly hydrogen-bonding, proton configurations. The spectrum for the lower Sc concentration, x = 0.45, does not feature such a band but a broader, weaker, O–H stretching band between approximately 2500 and 3700 cm-1, suggesting that the protons are more homogeneously distributed over a range of different local proton coordinations in this relatively weakly doped material. A comparison to the IR spectra of powder samples of similar compositions suggests that for x = 0.45, the spectra and proton coordination of films and powder samples are similar, whereas for x = 0.54 and 0.64, a larger fraction of protons seems to be located in weakly hydrogen-bonding proton configurations in the films compared to the respective powder samples.
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| 40. |
- Naumovska, Elena, 1995, et al.
(författare)
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Local structure of hydrated nanocrystalline films of the proton conductor BaZr1-xScxO3-x/2 studied by infrared spectroscopy
- 2024
-
Ingår i: Vibrational Spectroscopy. - : Elsevier. - 0924-2031 .- 1873-3697. ; 130
-
Tidskriftsartikel (refereegranskat)abstract
- We report results from a study of the local structure of hydrated nanocrystalline 2 m films of the well known proton conductor BaZr1-xScxO3-x/2 with x = 0.45, 0.54 and 0.64, using infrared (IR) spectroscopy. The films were prepared by magnetron sputtering. Analysis of the IR spectra focused on the O–H stretching region (2000—3700 cm-1), which reveals the presence of several distinct O–H stretching bands for which the intensity and frequency of each band vary in an unsystematic manner with Sc concentration. The spectra for the two higher Sc concentrations, x = 0.54 and 0.64, exhibit a distinct, highly intense O–H stretching band centered at around 3400–3500 cm-1, which is assigned to relatively symmetric, weakly hydrogen-bonding, proton configurations. The spectrum for the lower Sc concentration, x = 0.45, does not feature such a band but a broader, weaker, O–H stretching band between approximately 2500 and 3700 cm-1, suggesting that the protons are more homogeneously distributed over a range of different local proton coordinations in this relatively weakly doped material. A comparison to the IR spectra of powder samples of similar compositions suggests that for x = 0.45, the spectra and proton coordination of films and powder samples are similar, whereas for x = 0.54 and 0.64, a larger fraction of protons seems to be located in weakly hydrogen-bonding proton configurations in the films compared to the respective powder samples.
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| 41. |
- Nielsen, Susanne, 1969, et al.
(författare)
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Social Factors, Sex, and Mortality Risk After Coronary Artery Bypass Grafting: A Population-Based Cohort Study
- 2019
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Ingår i: Journal of the American Heart Association. - 2047-9980. ; 8:6
-
Tidskriftsartikel (refereegranskat)abstract
- Background Little is known of the impact of social factors on mortality after coronary artery bypass grafting ( CABG ). We explored sex- and age-specific associations between mortality risk after CABG and marital status, income, and education. Methods and Results This population-based register study included 110742 CABG patients (21.3% women) from the SWEDEHEART registry (Swedish Web-system for Enhancement and Development of Evidence-based Care in Heart Disease Evaluated According to Recommended Therapies) operated 1992 to 2015. Cox regression models were used to study the relation between social factors and all-cause mortality. Never having been married compared with being married/cohabiting was associated with a higher risk in women than in men (hazard ratio 1.32, 95% CI 1.20-1.44) versus 1.17 (1.13-1.22), P=0.030 between sex. The lowest income quintile, compared with the highest, was associated with higher risk in men than in women (hazard ratio 1.44 [1.38-1.51] versus 1.25 [1.14-1.38], P=0.0036). Lowest education level was associated with higher risk without sex difference (hazard ratio 1.15 [1.11-1.19] versus 1.25 [1.16-1.35], P=0.75). For unmarried women aged 60 years at surgery with low income and low education, mortality 10years after surgery was 18%, compared with 11% in married women with high income and higher education level. The median life expectancy was 4.8years shorter. Corresponding figures for 60-year-old men were 21% versus 12% mortality risk at 10 years and 5.0years shorter life expectancy. Conclusions There are strong associations between social factors and mortality risk after CABG in both men and women. These results emphasize the importance of developing and implementing secondary prevention strategies for CABG patients with disadvantages in social factors.
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| 42. |
- Nzulu, Gabriel Kofi, 1974-, et al.
(författare)
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Growth and thermal stability of Sc-doped BaZrO3 thin films deposited on single crystal substrates
- 2023
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 772
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Tidskriftsartikel (refereegranskat)abstract
- Thin films of BaZr1-xScxO3-x/2, (0 ≤ x ≤ 0.64), well known as proton conducting solid electrolytes for intermediatetemperature solid oxide fuel cell, were deposited by magnetron sputtering. X-ray diffraction analysis of theas deposited films reveals the presence of single-phase perovskite structure. The films were deposited on fourdifferent substrates (c-Al2O3, LaAlO3〈100〉, LaAlO3〈110〉, LaAlO3〈111〉) yielding random, (110)- or (100)-orientedfilms. The stability of the as-deposited films was assessed by annealing in air at 600 ◦C for 2 h. Theannealing treatment revealed instabilities of the perovskite structure for the (110) and randomly oriented films,but not for (100) oriented film. The instability of the coating under heat treatment was attributed to the lowoxygen content in the film (understoichiometry) prior annealing combined with the surface energy and atomiclayers stacking along the growth direction. An understoichiometric (100) oriented perovskite films showedhigher stability of the structure under an annealing in air at 600 ◦C.
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| 43. |
- Sanchez, Carmen, et al.
(författare)
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Characterization of Reduced and Surface-Modified Graphene Oxide in Poly(Ethylene-co-Butyl Acrylate) Composites for Electrical Applications
- 2019
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 11:4
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Tidskriftsartikel (refereegranskat)abstract
- Promising electrical field grading materials (FGMs) for high-voltage direct-current (HVDC) applications have been designed by dispersing reduced graphene oxide (rGO) grafted with relatively short chains of poly (n-butyl methacrylate) (PBMA) in a poly(ethylene-co-butyl acrylate) (EBA) matrix. All rGO-PBMA composites with a filler fraction above 3 vol.% exhibited a distinct non-linear resistivity with increasing electric field; and it was confirmed that the resistivity could be tailored by changing the PBMA graft length or the rGO filler fraction. A combined image analysis- and Monte-Carlo simulation strategy revealed that the addition of PBMA grafts improved the enthalpic solubility of rGO in EBA; resulting in improved particle dispersion and more controlled flake-to-flake distances. The addition of rGO and rGO-PBMAs increased the modulus of the materials up to 200% and the strain did not vary significantly as compared to that of the reference matrix for the rGO-PBMA-2 vol.% composites; indicating that the interphase between the rGO and EBA was subsequently improved. The new composites have comparable electrical properties as today's commercial FGMs; but are lighter and less brittle due to a lower filler fraction of semi-conductive particles (3 vol.% instead of 30-40 vol.%).
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| 44. |
- Stolt, Henrik, et al.
(författare)
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A comparison of the in vitro effects of three fibrinogen concentrates on clot strength in blood samples from cardiac surgery patients
- 2021
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 65:10, s. 1439-1446
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Tidskriftsartikel (refereegranskat)abstract
- Background Fibrinogen concentrate is used clinically to improve hemostasis in bleeding patients. We investigated and compared the efficacy of three commercially available fibrinogen concentrates to improve clot strength in blood samples from cardiac surgery patients. Objectives Postoperative blood samples were collected from 23 cardiac surgery patients. Samples were each divided into four vials, each supplemented with 1.125 mg of fibrinogen of one of three fibrinogen concentrates (RiaSTAP(R), Fibryga(R), FibCLOT(R)), or placebo. The fibrinogen dose corresponded to 2.5 g per 70 kg of body weight. Clot strength after supplementation was assessed in duplicate with rotational thromboelastometry (ROTEM(R)) using FIBTEM maximum clot firmness, EXTEM clot formation time, and maximum clot firmness assays. Results In vitro fibrinogen concentrate supplementation of the samples resulted in higher plasma fibrinogen concentrations and improved clot strength with all three concentrates. Supplementation with FibCLOT increased FIBTEM maximum clot firmness (+46% [25th-75th percentile 35-55] compared to placebo) significantly more than did supplementation with Fibryga (+26% [21-35]) and RiaSTAP (+29% [22-47], p < .001). FibCLOT supplementation also shortened EXTEM clot formation time and increased EXTEM maximum clot firmness to a greater extent than did the other concentrates (both p < .001). Conclusions At the selected dose, FibCLOT was more effective than Fibryga and RiaSTAP in restoring clot strength in postoperative blood samples from cardiac surgery patients. These results may have implications for the choice of fibrinogen concentrate and dosing.
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| 45. |
- Ternström, Lisa, 1972, et al.
(författare)
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Plasma activity of individual coagulation factors, hemodilution and blood loss after cardiac surgery: a prospective observational study.
- 2010
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Ingår i: Thrombosis research. - : Elsevier BV. - 1879-2472 .- 0049-3848. ; 126:2
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Hemodilution and consumption of coagulation factors during cardiopulmonary bypass has been suggested to contribute to bleeding complications after cardiac surgery. The aim was to describe the activity of individual coagulation factors after CABG in relation to hemodilution and postoperative bleeding. MATERIALS AND METHODS: Plasma concentrations of fibrinogen and plasma activity of FII, FV, FVII, FVIII, FIX, FX, FXI and FXIII adjusted for hemodilution were analysed in 57 CABG patients before, and 2h and 24h after surgery. Postoperative bleeding was registered and correlations to coagulation factor activity were calculated. RESULTS: Adjusted plasma concentration of fibrinogen (-14+/-6%), and plasma activity of FII (-9+/-6%), FV (-13+/-8%), FX (-13+/-7%) and FXIII (-9+/-14%) were reduced two hours after surgery compared to baseline (all p<0.001). FVII (+3+/-12%, p=0.34) and FXI (+1+/-19%, p=0.50) were unchanged, while FVIII (+23+/-44%, p=0.006) and FIX (+23+/-17%, p<0.001) increased. Twenty-four hours after surgery fibrinogen (+45+/-27%), FVIII (+93+/-66%) and FIX (+33+/-26%) were all increased (all p<0.001), while FVII (-37+/-14%, p<0.001), FXI (-4+/-18%, p=0.02) and FXIII (-6+/-15%, p=0.004) were decreased. Median postoperative blood loss was 380 ml/12h. There were significant inverse correlations between postoperative blood loss and fibrinogen concentration 2h after surgery (r=-0.33, p=0.019) and between postoperative blood loss and pre- and postoperative FXIII activity (r=-0.34, p=0.009 and r=-0.41, p=0.003, respectively), but not between blood loss and any of the other factors. CONCLUSIONS: There is a marked dissociation in plasma activity of individual coagulation factors after CABG. Plasma concentration of fibrinogen and factor XIII activity correlates inversely to postoperative blood loss after CABG.
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| 46. |
- Waldén, Katarina, 1983, et al.
(författare)
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Effects of fibrinogen supplementation on clot formation in blood samples from cardiac surgery patients before and after tranexamic acid administration
- 2019
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Ingår i: Transfusion Medicine. - : Wiley. - 0958-7578 .- 1365-3148. ; 29:5, s. 319-324
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To investigate if supplementation with fibrinogen concentrate to blood samples collected after tranexamic acid administration improve clot formation more than what can be achieved with fibrinogen in the absence of tranexamic acid. Background: It is not known if the combination of fibrinogen and tranexamic acid has additional effects than what can be achieved individually. Methods: Four blood samples were collected from 15 coronary artery bypass patients. Two samples were collected before surgery, before and after 2g tranexamic acid was administered. The preoperative samples were diluted to haematocrit 21%. Two samples were collected after surgery, before and after a second dose of 2g tranexamic acid. Fibrinogen concentrate corresponding to a dose of 3g in a 70-kg patient was added to the samples. Platelet-independent clotting time and maximum clot firmness assessed by thromboelastometry (ROTEM-FIBTEM®) were compared between the samples. Results: Administration of tranexamic acid shortened clotting time marginally (−6%) before surgery, P=0·029) but did not influence clot firmness. Fibrinogen concentrate shortened clotting time (−14% before and −12% after surgery, both P=0·003) and increased clot firmness (+51 and +39%, both P<0·001). The effects of fibrinogen did not differ before and after tranexamic acid administration. Fibrinolysis was not detected in any sample. Conclusions: The results of this in vitro study suggest that the enhancing effects of fibrinogen on clot firmness in blood samples from cardiac surgery patients are not further increased in the presence of tranexamic acid. Further studies on patients with ongoing bleeding and/or hyperfibrinolysis are necessary to validate the results. © 2019 British Blood Transfusion Society
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| 47. |
- Waldén, Katarina, 1983, et al.
(författare)
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Fibrinogen Concentrate to Cardiac Surgery Patients with Ongoing Bleeding does not Increase the Risk of Thromboembolic Complications or Death
- 2020
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Ingår i: Thrombosis and Haemostasis. - : Georg Thieme Verlag KG. - 0340-6245 .- 2567-689X. ; 120:3, s. 384-391
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Tidskriftsartikel (refereegranskat)abstract
- Background We investigated whether fibrinogen concentrate administration to bleeding patients is associated with an increased risk of thromboembolic complications and death. Methods All consecutive patients who underwent first-time cardiac surgery at Sahlgrenska University Hospital from 2009 to 2014 were included. Patients, who had received fibrinogen concentrate, were compared with those who had not received fibrinogen concentrate. The primary endpoint was a composite of thromboembolic complications and death within 1 year after surgery. Secondary endpoints included the composite and mortality within 30 days and mortality within 1 year after surgery. Multivariable logistic regression and Cox regression models were used to compare the groups. Propensity score (PS)-matched models were used for sensitivity analyses. Results A total of 5,408 patients were included in the present study, of which 564 (10.4%) received fibrinogen concentrate. The composite endpoint occurred in 3.5% of patients at 30 days and 10.5% at 1 year. There was no significant difference between the groups in the composite endpoint at 1 year (adjusted hazard ratio [HR]: 1.11, 95% confidence interval [CI]: 0.84-1.46, p = 0.45) or in the secondary endpoints, that is, mortality at 1 year (adjusted HR: 1.38, 95% CI: 0.93-2.04, p = 0.11), composite at 30 days (adjusted odds ratio [OR]: 1.07, 95% CI: 0.64-1.81, p = 0.79) and mortality at 30 days (adjusted OR: 1.00, 95% CI: 0.51-1.96, p = 0.50). The results of the sensitivity analyses were consistent with those of main analyses. Conclusion Perioperative administration of fibrinogen concentrate to bleeding cardiac surgery patients is not associated with an increased risk of thromboembolic complications or death.
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| 48. |
- Walden, Katarina, et al.
(författare)
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Low Preoperative Fibrinogen Plasma Concentration Is Associated With Excessive Bleeding After Cardiac Operations
- 2014
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Ingår i: Annals of Thoracic Surgery. - : Elsevier BV. - 0003-4975. ; 97:4, s. 1199-1206
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Tidskriftsartikel (refereegranskat)abstract
- Background. Data from small selected patient populations suggest that the preoperative plasma concentration of fibrinogen influences postoperative blood loss and red blood cell transfusion after cardiac operations, but there are also conflicting reports. We assessed the importance of preoperative fibrinogen concentration for excessive bleeding and red cell blood transfusion in a large cohort of mixed cardiac surgical patients. Methods. We included 1,954 cardiac surgical patients in a prospective observational study. The plasma concentration was measured on the day before the operation. Blood loss (mediastinal drain volume) during the first 12 postoperative hours and red blood cell transfusion during the hospital stay were registered and related to fibrinogen concentration with logistic regression models. Excessive bleeding was defined as postoperative blood loss exceeding 1,000 mL/12 hours. Results. The preoperative fibrinogen concentration was inversely proportional to the prevalence of excessive bleeding in univariate testing (odds ratio [OR], 0.75; 95% confidence interval [CI], 0.64 to 0.89 per g/L; p = 0.001) and also in a multiple model adjusted for age, sex, body mass index, renal function, acuteness of the operation, cardiopulmonary bypass time, clopidogrel use less than 5 days before the operation, and type of operation (OR for fibrinogen, 0.82; 95% CI, 0.69 to 0.97; p = 0.024). In contrast, the prevalence of red cell blood transfusion increased with increasing fibrinogen levels in univariate testing (OR, 1.36; 95% CI, 1.24 to 1.49; p < 0.001) but not in a multiple model (OR, 1.10; 95% CI, 0.89 to 1.28; p = 0.49). Conclusions. Preoperative plasma concentration of fibrinogen is independently associated with excessive bleeding after cardiac operations but not with red blood cell transfusion. (C) 2014 by The Society of Thoracic Surgeons
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| 49. |
- Wallgren, Marcus, 1978-, et al.
(författare)
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Reconstitution of the Anti-Apoptotic Bcl-2 Protein into Lipid Membranes and Biophysical Evidence for Its Detergent-Driven Association with the Pro-Apoptotic Bax Protein
- 2013
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- The anti-apoptotic B-cell CLL/lymphoma-2 (Bcl-2) protein and its counterpart, the pro-apoptotic Bcl-2-associated X protein (Bax), are key players in the regulation of the mitochondrial pathway of apoptosis. However, how they interact at the mitochondrial outer membrane (MOM) and there determine whether the cell will live or be sentenced to death remains unknown. Competing models have been presented that describe how Bcl-2 inhibits the cell-killing activity of Bax, which is common in treatment-resistant tumors where Bcl-2 is overexpressed. Some studies suggest that Bcl-2 binds directly to and sequesters Bax, while others suggest an indirect process whereby Bcl-2 blocks BH3-only proteins and prevents them from activating Bax. Here we present the results of a biophysical study in which we investigated the putative interaction of solubilized full-length human Bcl-2 with Bax and the scope for incorporating the former into a native-like lipid environment. Far-UV circular dichroism (CD) spectroscopy was used to detect direct Bcl-2-Bax-interactions in the presence of polyoxyethylene-(23)-lauryl-ether (Brij-35) detergent at a level below its critical micelle concentration (CMC). Additional surface plasmon resonance (SPR) measurements confirmed this observation and revealed a high affinity between the Bax and Bcl-2 proteins. Upon formation of this protein-protein complex, Bax also prevented the binding of antimycin A(2) (a known inhibitory ligand of Bcl-2) to the Bcl-2 protein, as fluorescence spectroscopy experiments showed. In addition, Bcl-2 was able to form mixed micelles with Triton X-100 solubilized neutral phospholipids in the presence of high concentrations of Brij-35 (above its CMC). Following detergent removal, the integral membrane protein was found to have been fully reconstituted into a native-like membrane environment, as confirmed by ultracentrifugation and subsequent SDS-PAGE experiments.
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