| 1. |
- Patel, Y., et al.
(författare)
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Virtual Ontogeny of Cortical Growth Preceding Mental Illness
- 2022
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Ingår i: Biological Psychiatry. - : Elsevier BV. - 0006-3223 .- 1873-2402. ; 92:4, s. 299-313
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Tidskriftsartikel (refereegranskat)abstract
- Background: Morphology of the human cerebral cortex differs across psychiatric disorders, with neurobiology and developmental origins mostly undetermined. Deviations in the tangential growth of the cerebral cortex during pre/perinatal periods may be reflected in individual variations in cortical surface area later in life. Methods: Interregional profiles of group differences in surface area between cases and controls were generated using T1-weighted magnetic resonance imaging from 27,359 individuals including those with attention-deficit/hyperactivity disorder, autism spectrum disorder, bipolar disorder, major depressive disorder, schizophrenia, and high general psychopathology (through the Child Behavior Checklist). Similarity of interregional profiles of group differences in surface area and prenatal cell-specific gene expression was assessed. Results: Across the 11 cortical regions, group differences in cortical area for attention-deficit/hyperactivity disorder, schizophrenia, and Child Behavior Checklist were dominant in multimodal association cortices. The same interregional profiles were also associated with interregional profiles of (prenatal) gene expression specific to proliferative cells, namely radial glia and intermediate progenitor cells (greater expression, larger difference), as well as differentiated cells, namely excitatory neurons and endothelial and mural cells (greater expression, smaller difference). Finally, these cell types were implicated in known pre/perinatal risk factors for psychosis. Genes coexpressed with radial glia were enriched with genes implicated in congenital abnormalities, birth weight, hypoxia, and starvation. Genes coexpressed with endothelial and mural genes were enriched with genes associated with maternal hypertension and preterm birth. Conclusions: Our findings support a neurodevelopmental model of vulnerability to mental illness whereby prenatal risk factors acting through cell-specific processes lead to deviations from typical brain development during pregnancy.
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Sønderby, Ida E., et al.
(författare)
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1q21.1 distal copy number variants are associated with cerebral and cognitive alterations in humans
- 2021
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Ingår i: Translational Psychiatry. - : Nature Publishing Group. - 2158-3188. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Low-frequency 1q21.1 distal deletion and duplication copy number variant (CNV) carriers are predisposed to multiple neurodevelopmental disorders, including schizophrenia, autism and intellectual disability. Human carriers display a high prevalence of micro- and macrocephaly in deletion and duplication carriers, respectively. The underlying brain structural diversity remains largely unknown. We systematically called CNVs in 38 cohorts from the large-scale ENIGMA-CNV collaboration and the UK Biobank and identified 28 1q21.1 distal deletion and 22 duplication carriers and 37,088 non-carriers (48% male) derived from 15 distinct magnetic resonance imaging scanner sites. With standardized methods, we compared subcortical and cortical brain measures (all) and cognitive performance (UK Biobank only) between carrier groups also testing for mediation of brain structure on cognition. We identified positive dosage effects of copy number on intracranial volume (ICV) and total cortical surface area, with the largest effects in frontal and cingulate cortices, and negative dosage effects on caudate and hippocampal volumes. The carriers displayed distinct cognitive deficit profiles in cognitive tasks from the UK Biobank with intermediate decreases in duplication carriers and somewhat larger in deletion carriers-the latter potentially mediated by ICV or cortical surface area. These results shed light on pathobiological mechanisms of neurodevelopmental disorders, by demonstrating gene dose effect on specific brain structures and effect on cognitive function.
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| 6. |
- van der Meer, Dennis, et al.
(författare)
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Association of Copy Number Variation of the 15q11.2 BP1-BP2 Region With Cortical and Subcortical Morphology and Cognition
- 2020
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Ingår i: JAMA psychiatry. - : American Medical Association (AMA). - 2168-6238 .- 2168-622X. ; 77:4, s. 420-430
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Tidskriftsartikel (refereegranskat)abstract
- Importance: Recurrent microdeletions and duplications in the genomic region 15q11.2 between breakpoints 1 (BP1) and 2 (BP2) are associated with neurodevelopmental disorders. These structural variants are present in 0.5% to 1.0% of the population, making 15q11.2 BP1-BP2 the site of the most prevalent known pathogenic copy number variation (CNV). It is unknown to what extent this CNV influences brain structure and affects cognitive abilities.Objective: To determine the association of the 15q11.2 BP1-BP2 deletion and duplication CNVs with cortical and subcortical brain morphology and cognitive task performance.Design, Setting, and Participants: In this genetic association study, T1-weighted brain magnetic resonance imaging were combined with genetic data from the ENIGMA-CNV consortium and the UK Biobank, with a replication cohort from Iceland. In total, 203 deletion carriers, 45 247 noncarriers, and 306 duplication carriers were included. Data were collected from August 2015 to April 2019, and data were analyzed from September 2018 to September 2019.Main Outcomes and Measures: The associations of the CNV with global and regional measures of surface area and cortical thickness as well as subcortical volumes were investigated, correcting for age, age2, sex, scanner, and intracranial volume. Additionally, measures of cognitive ability were analyzed in the full UK Biobank cohort.Results: Of 45 756 included individuals, the mean (SD) age was 55.8 (18.3) years, and 23 754 (51.9%) were female. Compared with noncarriers, deletion carriers had a lower surface area (Cohen d = -0.41; SE, 0.08; P = 4.9 × 10-8), thicker cortex (Cohen d = 0.36; SE, 0.07; P = 1.3 × 10-7), and a smaller nucleus accumbens (Cohen d = -0.27; SE, 0.07; P = 7.3 × 10-5). There was also a significant negative dose response on cortical thickness (β = -0.24; SE, 0.05; P = 6.8 × 10-7). Regional cortical analyses showed a localization of the effects to the frontal, cingulate, and parietal lobes. Further, cognitive ability was lower for deletion carriers compared with noncarriers on 5 of 7 tasks.Conclusions and Relevance: These findings, from the largest CNV neuroimaging study to date, provide evidence that 15q11.2 BP1-BP2 structural variation is associated with brain morphology and cognition, with deletion carriers being particularly affected. The pattern of results fits with known molecular functions of genes in the 15q11.2 BP1-BP2 region and suggests involvement of these genes in neuronal plasticity. These neurobiological effects likely contribute to the association of this CNV with neurodevelopmental disorders.
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| 7. |
- Belov, Vladimir, et al.
(författare)
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Multi-site benchmark classification of major depressive disorder using machine learning on cortical and subcortical measures
- 2024
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Ingår i: Scientific Reports. - : NATURE PORTFOLIO. - 2045-2322. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Machine learning (ML) techniques have gained popularity in the neuroimaging field due to their potential for classifying neuropsychiatric disorders. However, the diagnostic predictive power of the existing algorithms has been limited by small sample sizes, lack of representativeness, data leakage, and/or overfitting. Here, we overcome these limitations with the largest multi-site sample size to date (N = 5365) to provide a generalizable ML classification benchmark of major depressive disorder (MDD) using shallow linear and non-linear models. Leveraging brain measures from standardized ENIGMA analysis pipelines in FreeSurfer, we were able to classify MDD versus healthy controls (HC) with a balanced accuracy of around 62%. But after harmonizing the data, e.g., using ComBat, the balanced accuracy dropped to approximately 52%. Accuracy results close to random chance levels were also observed in stratified groups according to age of onset, antidepressant use, number of episodes and sex. Future studies incorporating higher dimensional brain imaging/phenotype features, and/or using more advanced machine and deep learning methods may yield more encouraging prospects.
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| 8. |
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| 9. |
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| 10. |
- Hilbert, Kevin, et al.
(författare)
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Cortical and Subcortical Brain Alterations in Specific Phobia and Its Animal and Blood-Injection-Injury Subtypes: A Mega-Analysis From the ENIGMA Anxiety Working Group.
- 2024
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Ingår i: The American Journal of Psychiatry. - 1535-7228.
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Tidskriftsartikel (refereegranskat)abstract
- Specific phobia is a common anxiety disorder, but the literature on associated brain structure alterations exhibits substantial gaps. The ENIGMA Anxiety Working Group examined brain structure differences between individuals with specific phobias and healthy control subjects as well as between the animal and blood-injection-injury (BII) subtypes of specific phobia. Additionally, the authors investigated associations of brain structure with symptom severity and age (youths vs. adults).Data sets from 31 original studies were combined to create a final sample with 1,452 participants with phobia and 2,991 healthy participants (62.7% female; ages 5-90). Imaging processing and quality control were performed using established ENIGMA protocols. Subcortical volumes as well as cortical surface area and thickness were examined in a preregistered analysis.Compared with the healthy control group, the phobia group showed mostly smaller subcortical volumes, mixed surface differences, and larger cortical thickness across a substantial number of regions. The phobia subgroups also showed differences, including, as hypothesized, larger medial orbitofrontal cortex thickness in BII phobia (N=182) compared with animal phobia (N=739). All findings were driven by adult participants; no significant results were observed in children and adolescents.Brain alterations associated with specific phobia exceeded those of other anxiety disorders in comparable analyses in extent and effect size and were not limited to reductions in brain structure. Moreover, phenomenological differences between phobia subgroups were reflected in diverging neural underpinnings, including brain areas related to fear processing and higher cognitive processes. The findings implicate brain structure alterations in specific phobia, although subcortical alterations in particular may also relate to broader internalizing psychopathology.
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| 11. |
- Groenewold, Nynke A., et al.
(författare)
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Volume of subcortical brain regions in social anxiety disorder : mega-analytic results from 37 samples in the ENIGMA-Anxiety Working Group
- 2023
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Ingår i: Molecular Psychiatry. - : Springer Nature. - 1359-4184 .- 1476-5578. ; 28:3, s. 1079-1089
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Tidskriftsartikel (refereegranskat)abstract
- There is limited convergence in neuroimaging investigations into volumes of subcortical brain regions in social anxiety disorder (SAD). The inconsistent findings may arise from variations in methodological approaches across studies, including sample selection based on age and clinical characteristics. The ENIGMA-Anxiety Working Group initiated a global mega-analysis to determine whether differences in subcortical volumes can be detected in adults and adolescents with SAD relative to healthy controls. Volumetric data from 37 international samples with 1115 SAD patients and 2775 controls were obtained from ENIGMA-standardized protocols for image segmentation and quality assurance. Linear mixed-effects analyses were adjusted for comparisons across seven subcortical regions in each hemisphere using family-wise error (FWE)-correction. Mixed-effects d effect sizes were calculated. In the full sample, SAD patients showed smaller bilateral putamen volume than controls (left: d = −0.077, pFWE = 0.037; right: d = −0.104, pFWE = 0.001), and a significant interaction between SAD and age was found for the left putamen (r = −0.034, pFWE = 0.045). Smaller bilateral putamen volumes (left: d = −0.141, pFWE < 0.001; right: d = −0.158, pFWE < 0.001) and larger bilateral pallidum volumes (left: d = 0.129, pFWE = 0.006; right: d = 0.099, pFWE = 0.046) were detected in adult SAD patients relative to controls, but no volumetric differences were apparent in adolescent SAD patients relative to controls. Comorbid anxiety disorders and age of SAD onset were additional determinants of SAD-related volumetric differences in subcortical regions. To conclude, subtle volumetric alterations in subcortical regions in SAD were detected. Heterogeneity in age and clinical characteristics may partly explain inconsistencies in previous findings. The association between alterations in subcortical volumes and SAD illness progression deserves further investigation, especially from adolescence into adulthood.
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| 12. |
- Thompson, PM, et al.
(författare)
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ENIGMA and global neuroscience: A decade of large-scale studies of the brain in health and disease across more than 40 countries
- 2020
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Ingår i: Translational psychiatry. - : Springer Science and Business Media LLC. - 2158-3188. ; 10:1, s. 100-
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Tidskriftsartikel (refereegranskat)abstract
- This review summarizes the last decade of work by the ENIGMA (Enhancing NeuroImaging Genetics through Meta Analysis) Consortium, a global alliance of over 1400 scientists across 43 countries, studying the human brain in health and disease. Building on large-scale genetic studies that discovered the first robustly replicated genetic loci associated with brain metrics, ENIGMA has diversified into over 50 working groups (WGs), pooling worldwide data and expertise to answer fundamental questions in neuroscience, psychiatry, neurology, and genetics. Most ENIGMA WGs focus on specific psychiatric and neurological conditions, other WGs study normal variation due to sex and gender differences, or development and aging; still other WGs develop methodological pipelines and tools to facilitate harmonized analyses of “big data” (i.e., genetic and epigenetic data, multimodal MRI, and electroencephalography data). These international efforts have yielded the largest neuroimaging studies to date in schizophrenia, bipolar disorder, major depressive disorder, post-traumatic stress disorder, substance use disorders, obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism spectrum disorders, epilepsy, and 22q11.2 deletion syndrome. More recent ENIGMA WGs have formed to study anxiety disorders, suicidal thoughts and behavior, sleep and insomnia, eating disorders, irritability, brain injury, antisocial personality and conduct disorder, and dissociative identity disorder. Here, we summarize the first decade of ENIGMA’s activities and ongoing projects, and describe the successes and challenges encountered along the way. We highlight the advantages of collaborative large-scale coordinated data analyses for testing reproducibility and robustness of findings, offering the opportunity to identify brain systems involved in clinical syndromes across diverse samples and associated genetic, environmental, demographic, cognitive, and psychosocial factors.
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| 13. |
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| 14. |
- Andersson, Charlotte I J, et al.
(författare)
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Error-prone PCR of Vitreoscilla hemoglobin (VHb) to support the growth of microaerobic Escherichia coli
- 2000
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Ingår i: Biotechnology and Bioengineering. - 0006-3592. ; 70:4, s. 55-446
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Tidskriftsartikel (refereegranskat)abstract
- Expression of the gene encoding bacterial hemoglobin (VHb) from Vitreoscilla has been previously used to improve recombinant cell growth and enhance product formation under microaerobic conditions. It is very likely that the properties of VHb are not optimized for foreign hosts; therefore, we used error-prone PCR to generate a number of randomly mutated vhb genes to be expressed and studied in Escherichia coli. In addition, the mutated VHb proteins also contained an extension of eight residues (MTMITPSF) at the amino terminus. VHb mutants were screened for improved growth properties under microaerobic conditions and 15 clones expressing mutated hemoglobin protein were selected for further characterization and cultivated in a microaerobic bioreactor to analyze the physiological effects of novel VHb proteins on cell growth. The expression of four VHb mutants, carried by pVM20, pVM50, pVM104, and pVM134, were able to enhance microaerobic growth of E. coli by approximately 22%, 155%, 50%, and 90%, respectively, with a concomitant decrease of acetate excretion into the culture medium. The vhb gene in pVM20 contains two mutations substituting residues Glu19(A17) and Glu137(H23) to Gly. pVM50 expresses a VHb protein carrying two mutations: His36(C1) to Arg36 and Gln66(E20) to Arg66. pVM104 and pVM134 express VHb proteins carrying the mutations Ala56(E10) to Gly and Ile24(B5) to Thr, respectively. Our experiments also indicate that the positive effects elicited by mutant VHb-expression from pVM20 and pVM50 are linked to the peptide tail. Removal of the N-terminal sequence reduced cell growth approximately 23% and 53%, respectively, relative to wild-type controls. These results clearly demonstrate that it is possible to obtain mutated VHb proteins with improved characteristics for improving microaerobic growth of E. coli by using combined mutation techniques, addition of a peptide tail, and random error-prone PCR.
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| 15. |
- Del Chiaro, M, et al.
(författare)
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European evidence-based guidelines on pancreatic cystic neoplasms
- 2018
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Ingår i: Gut. - : BMJ. - 1468-3288 .- 0017-5749. ; 67:5, s. 789-804
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Tidskriftsartikel (refereegranskat)abstract
- Evidence-based guidelines on the management of pancreatic cystic neoplasms (PCN) are lacking. This guideline is a joint initiative of the European Study Group on Cystic Tumours of the Pancreas, United European Gastroenterology, European Pancreatic Club, European-African Hepato-Pancreato-Biliary Association, European Digestive Surgery, and the European Society of Gastrointestinal Endoscopy. It replaces the 2013 European consensus statement guidelines on PCN. European and non-European experts performed systematic reviews and used GRADE methodology to answer relevant clinical questions on nine topics (biomarkers, radiology, endoscopy, intraductal papillary mucinous neoplasm (IPMN), mucinous cystic neoplasm (MCN), serous cystic neoplasm, rare cysts, (neo)adjuvant treatment, and pathology). Recommendations include conservative management, relative and absolute indications for surgery. A conservative approach is recommended for asymptomatic MCN and IPMN measuring <40 mm without an enhancing nodule. Relative indications for surgery in IPMN include a main pancreatic duct (MPD) diameter between 5 and 9.9 mm or a cyst diameter ≥40 mm. Absolute indications for surgery in IPMN, due to the high-risk of malignant transformation, include jaundice, an enhancing mural nodule >5 mm, and MPD diameter >10 mm. Lifelong follow-up of IPMN is recommended in patients who are fit for surgery. The European evidence-based guidelines on PCN aim to improve the diagnosis and management of PCN.
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| 16. |
- Rothenberg, Elisabet, et al.
(författare)
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Texture-modified meat and carrot products for elderly people with dysphagia : preference in relation to health and oral status
- 2007
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Ingår i: Scandinavian Journal of Food and Nutrition. - : Taylor & Francis. - 1748-2976 .- 1748-2984. ; 51:4, s. 141-147
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Tidskriftsartikel (refereegranskat)abstract
- Background: Reduced taste and smell, chewing problems and swallowing dysfunction are common among elderly people and affect perception, food choice and the ability to eat. Objective: To study the preference for texture-modified carrot and meat products in elderly people aiming to meet the needs of people with impaired chewing and/or swallowing. Design: Data were collected using questionnaires focusing on health, oral status and preference for the products. Altogether, 108 elderly people in ordinary housing (OH) and 50 living in special housing (SH) in Malmö (SH-M) and Göteborg (SH-G) participated. Results: 19% had a body mass index 522, predominantly in SH (24%). Stroke was reported by 20% of the subjects in SH. Among those with subjectively experienced difficulties in swallowing (12%), 58% reported coughing, 21% a gurgly voice in association with food intake and 50% obstruction during swallowing. Only 20% with subjective swallowing difficulties had been specifically examined regarding this problem. All the tested products were easy to masticate and swallow. Compared with OH, people in SH-M found the meatproducts easier to masticate and swallow. Compared with OH, subjects in SH found the carrot products easier to masticate. Conclusions: There is a need to develop tasty texture-modified nutritious food products for people with mastication and/or swallowing problems. Possible factors for differences in preference between groups, in this study OH and SH, may be related to health status in general and specifically mastication and swallowing functions.
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| 17. |
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| 18. |
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| 19. |
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| 20. |
- Cooper, Chris E., et al.
(författare)
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Haptoglobin Binding Stabilizes Hemoglobin Ferryl Iron and the Globin Radical on Tyrosine beta 145
- 2013
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Ingår i: Antioxidants & Redox Signaling. - 1557-7716. ; 18:17, s. 2264-2273
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Hemoglobin (Hb) becomes toxic when released from the erythrocyte. The acute phase protein haptoglobin (Hp) binds avidly to Hb and decreases oxidative damage to Hb itself and to the surrounding proteins and lipids. However, the molecular mechanism underpinning Hp protection is to date unclear. The aim of this study was to use electron paramagnetic resonance (EPR) spectroscopy, stopped flow optical spectrophotometry, and site-directed mutagenesis to explore the mechanism and specifically the role of specific tyrosine residues in this protection. Results: Following peroxide challenge Hb produces reactive oxidative intermediates in the form of ferryl heme and globin free radicals. Hp binding increases the steady state level of ferryl formation during Hb-catalyzed lipid peroxidation, while at the same time dramatically inhibiting the overall reaction rate. This enhanced ferryl stability is also seen in the absence of lipids and in the presence of external reductants. Hp binding is not accompanied by a decrease in the pK of ferryl protonation; the protonated ferryl species still forms, but is intrinsically less reactive. Ferryl stabilization is accompanied by a significant increase in the concentration of the peroxide-induced tyrosine free radical. EPR spectral parameters and mutagenesis studies suggest that this radical is located on tyrosine 145, the penultimate C-terminal amino acid on the beta Hb subunit. Innovation: Hp binding decreases both the ferryl iron and free radical reactivity of Hb. Conclusion: Hp protects against Hb-induced damage in the vasculature, not by preventing the primary reactivity of heme oxidants, but by rendering the resultant protein products less damaging. Antioxid. Redox Signal. 18, 2264-2273.
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| 21. |
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| 22. |
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| 23. |
- Farris, Alton B., et al.
(författare)
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Banff Digital Pathology Working Group: Image Bank, Artificial Intelligence Algorithm, and Challenge Trial Developments
- 2023
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Ingår i: Transplant International. - : FRONTIERS MEDIA SA. - 0934-0874 .- 1432-2277. ; 36
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Tidskriftsartikel (refereegranskat)abstract
- The Banff Digital Pathology Working Group (DPWG) was established with the goal to establish a digital pathology repository; develop, validate, and share models for image analysis; and foster collaborations using regular videoconferencing. During the calls, a variety of artificial intelligence (AI)-based support systems for transplantation pathology were presented. Potential collaborations in a competition/trial on AI applied to kidney transplant specimens, including the DIAGGRAFT challenge (staining of biopsies at multiple institutions, pathologists visual assessment, and development and validation of new and pre-existing Banff scoring algorithms), were also discussed. To determine the next steps, a survey was conducted, primarily focusing on the feasibility of establishing a digital pathology repository and identifying potential hosts. Sixteen of the 35 respondents (46%) had access to a server hosting a digital pathology repository, with 2 respondents that could serve as a potential host at no cost to the DPWG. The 16 digital pathology repositories collected specimens from various organs, with the largest constituent being kidney (n = 12,870 specimens). A DPWG pilot digital pathology repository was established, and there are plans for a competition/trial with the DIAGGRAFT project. Utilizing existing resources and previously established models, the Banff DPWG is establishing new resources for the Banff community.
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| 24. |
- Ferguson, R. J., et al.
(författare)
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ASA class is associated with early revision and reoperation after total hip arthroplasty: an analysis of the Geneva and Swedish Hip Arthroplasty Registries
- 2019
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Ingår i: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 90:4, s. 324-330
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Tidskriftsartikel (refereegranskat)abstract
- - Background and purpose — Data from several joint replacement registries suggest that the rate of early revision surgery after primary total hip arthroplasty (THA) is increasing. The ASA class, now widely recorded in arthroplasty registries, may predict early revision. We investigated the influence of ASA class on the risk of revision and other reoperation within 3 months and within 5 years of primary THA. Patients and methods — We used data from the Geneva and Swedish Hip Arthroplasty Registries, on primary elective THAs performed in 1996–2016 and 2008–2016, respectively. 5,319 and 122,241 THAs were included, respectively. Outcomes were all-cause revision and other reoperations evaluated using Kaplan–Meier survival and Cox regression analyses. Results — Within 3 months after surgery, higher ASA class was associated with greater risk of revision and other reoperation. 3-month cumulative incidences of revision by ASA class I, II, and III–IV respectively, were 0.6%, 0.7%, and 2.3% in Geneva and 0.5%, 0.8%, and 1.6% in Sweden. 3-month cumulative incidences of other reoperation were 0.4%, 0.7%, and 0.9% in Geneva and 0.2%, 0.4%, and 0.7% in Sweden. Adjusted hazard ratios (ASA III–IV vs. I) for revision within 3 months were 2.7 (95% CI 1.2–5.9) in Geneva and 3.3 (CI 2.6–4.0) in Sweden. Interpretation — Assessment of ASA class of patients prior to THA will facilitate risk stratification. Targeted risk-reduction strategies may be appropriate during the very early postoperative period for patients identified as at higher risk. Systematically recording ASA class in arthroplasty registries will permit risk adjustment and facilitate comparison of revision rates internationally. © 2019, © 2019 The Author(s). Published by Taylor & Francis on behalf of the Nordic Orthopedic Federation.
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| 25. |
- Jokipii-Lukkari, Soile, et al.
(författare)
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Dual targeted poplar ferredoxin NADP+ oxidoreductase interacts with hemoglobin 1
- 2016
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Ingår i: Plant Science. - : Elsevier BV. - 0168-9452. ; 247, s. 138-149
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Tidskriftsartikel (refereegranskat)abstract
- Previous reports have connected non-symbiotic and truncated hemoglobins (Hbs) to metabolism of nitric oxide (NO), an important signalling molecule involved in wood formation. We have studied the capability of poplar (Populus tremula × tremuloides) Hbs PttHb1 and PttTrHb proteins alone or with a flavin-protein reductase to relieve NO cytotoxicity in living cells. Complementation tests in a Hb-deficient, NO-sensitive yeast (Saccharomyces cerevisiae) δyhb1 mutant showed that neither PttHb1 nor PttTrHb alone protected cells against NO. To study the ability of Hbs to interact with a reductase, ferredoxin NADP+ oxidoreductase PtthFNR was characterized by sequencing and proteomics. To date, by far the greatest number of the known dual-targeted plant proteins are directed to chloroplasts and mitochondria. We discovered a novel variant of hFNR that lacks the plastid presequence and resides in cytosol. The coexpression of PttHb1 and PtthFNR partially restored NO resistance of the yeast δyhb1 mutant, whereas PttTrHb coexpressed with PtthFNR failed to rescue growth. YFP fusion proteins confirmed the interaction between PttHb1 and PtthFNR in plant cells. The structural modelling results indicate that PttHb1 and PtthFNR are able to interact as NO dioxygenase. This is the first report on dual targeting of central plant enzyme FNR to plastids and cytosol.
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| 26. |
- Matos, Tiago, et al.
(författare)
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Nucleic acid and protein extraction from electropermeabilized E. coli cells on a microfluidic chip.
- 2013
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Ingår i: Analyst. - : Royal Society of Chemistry (RSC). - 1364-5528. ; 138:24, s. 7347-7353
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Tidskriftsartikel (refereegranskat)abstract
- Due to the extensive use of nucleic acid and protein analysis of bacterial samples, there is a need for simple and rapid extraction protocols for both plasmid DNA and RNA molecules as well as reporter proteins like the green fluorescent protein (GFP). In this report, an electropermeability technique has been developed which is based on exposing E. coli cells to low voltages to allow extraction of nucleic acids and proteins. The flow-through electropermeability chip used consists of a microfluidic channel with integrated gold electrodes that promote cell envelope channel formation at low applied voltages. This will allow small biomolecules with diameters less than 30 A to rapidly diffuse from the permeabilized cells to the surrounding solution. By controlling the applied voltage, partial and transient to complete cell opening can be obtained. By using DC voltages below 0.5 V, cell lysis can be avoided and the transiently formed pores can be closed again and the cells survive. This method has been used to extract RNA and GFP molecules under conditions of electropermeability. Plasmid DNA could be recovered when the applied voltage was increased to 2 V, thus causing complete cell lysis.
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| 27. |
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| 28. |
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| 29. |
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| 30. |
- Schjørring, O. L., et al.
(författare)
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Intensive care doctors’ preferences for arterial oxygen tension levels in mechanically ventilated patients
- 2018
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 62:10, s. 1443-1451
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Tidskriftsartikel (refereegranskat)abstract
- Background: Oxygen is liberally administered in intensive care units (ICUs). Nevertheless, ICU doctors’ preferences for supplementing oxygen are inadequately described. The aim was to identify ICU doctors’ preferences for arterial oxygenation levels in mechanically ventilated adult ICU patients. Methods: In April to August 2016, an online multiple-choice 17-part-questionnaire was distributed to 1080 ICU doctors in seven Northern European countries. Repeated reminder e-mails were sent. The study ended in October 2016. Results: The response rate was 63%. When evaluating oxygenation 52% of respondents rated arterial oxygen tension (PaO2) the most important parameter; 24% a combination of PaO2 and arterial oxygen saturation (SaO2); and 23% preferred SaO2. Increasing, decreasing or not changing a default fraction of inspired oxygen of 0.50 showed preferences for a PaO2 around 8 kPa in patients with chronic obstructive pulmonary disease, a PaO2 around 10 kPa in patients with healthy lungs, acute respiratory distress syndrome or sepsis, and a PaO2 around 12 kPa in patients with cardiac or cerebral ischaemia. Eighty per cent would accept a PaO2 of 8 kPa or lower and 77% would accept a PaO2 of 12 kPa or higher in a clinical trial of oxygenation targets. Conclusion: Intensive care unit doctors preferred PaO2 to SaO2 in monitoring oxygen treatment when peripheral oxygen saturation was not included in the question. The identification of PaO2 as the preferred target and the thorough clarification of preferences are important when ascertaining optimal oxygenation targets. In particular when designing future clinical trials of higher vs lower oxygenation targets in ICU patients.
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| 31. |
- Silkstone, R S, et al.
(författare)
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The βLys66Tyr Variant of Human Hemoglobin as a Component of a Blood Substitute.
- 2016
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Ingår i: Advances in Experimental Medicine and Biology. - New York, NY : Springer New York. - 0065-2598. ; 876, s. 455-460
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Tidskriftsartikel (refereegranskat)abstract
- It has been proposed that introducing tyrosine residues into human hemoglobin (e.g. βPhe41Tyr) may be able to reduce the toxicity of the ferryl heme species in extracellular hemoglobin-based oxygen carriers (HBOC) by facilitating long-range electron transfer from endogenous and exogenous antioxidants. Surface-exposed residues lying close to the solvent exposed heme edge may be good candidates for mutations. We therefore studied the properties of the βLys66Tyr mutation. Hydrogen peroxide (H2O2) was added to generate the ferryl protein. The ferryl state in βLys66Tyr was more rapidly reduced to ferric (met) by ascorbate than recombinant wild type ((r)wt) or βPhe41Tyr. However, βLys66Tyr suffered more heme and globin damage following H2O2 addition as measured by UV/visible spectroscopy and HPLC analysis. βLys66Tyr differed notably from the (r)wt protein in other ways. In the ferrous state the βLys66Tyr forms oxy, CO, and NO bound heme complexes similar to (r)wt. However, the kinetics of CO binding to the mutant was faster than (r)wt, suggesting a more open heme crevice. In the ferric (met) form the typical met Hb acid-alkaline transition (H2O to (-)OH) appeared absent in the mutant protein. A biphasicity of cyanide binding was also evident. Expression in E. coli of the βLys66Tyr mutant was lower than the (r)wt protein, and purification included significant protein heterogeneity. Whilst, βLys66Tyr and (r)wt autoxidised (oxy to met) at similar rates, the oxygen p50 for βLys66Tyr was very low. Therefore, despite the apparent introduction of a new electron transfer pathway in the βLys66Tyr mutant, the heterogeneity, and susceptibility to oxidative damage argue against this mutant as a suitable starting material for a HBOC.
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| 32. |
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| 33. |
- Vasen, HFA, et al.
(författare)
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Decision analysis in the surgical treatment of patients with familial adenomatous polyposis: a Dutch-Scandinavian collaborative study including 659 patients
- 2001
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Ingår i: Gut. - : BMJ. - 0017-5749 .- 1468-3288. ; 49:2, s. 231-235
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Tidskriftsartikel (refereegranskat)abstract
- The choice of colorectal surgery in patients with familial adenomatous polyposis lies between the morbidity of proctocolectomy and ileum-pouch-anal anastomosis (IPAA) and the mortality from rectal cancer after total colectomy and ileorectal anastomosis (IRA). The aims of the present study were: (1) to assess the risk of dying from rectal cancer after IRA, (2) to compare the life expectancy between patients with an IRA and those with an IPAA, and (3) to investigate whether regular endoscopic examination of the rectum leads to detection of cancer at an earlier stage.METHODSClinical and pathological data on 659 patients who underwent colectomy and ileorectal anastomosis were collected from four national polyposis registries—that is, in Denmark, Finland, Sweden, and the Netherlands. Data were analysed using survival analysis methods. Decision analysis was used to compare the life expectancy between patients with an IRA and those with an IPAA.RESULTSA total of 47 patients developed rectal cancer after IRA. The risk of dying from rectal cancer was 12.5% (95% confidence interval 7.1–17.9%) by age 65. Compared with IRA, IPAA would lead to an increase in life expectancy of 1.8 years. Seventy five per cent of patients with rectal cancer had a negative rectoscopy within 12 months before the diagnosis.CONCLUSIONIRA is associated with substantial mortality due to rectal cancer. Follow up examinations of the rectum does not have sufficient preventive effect on morbidity and mortality of rectal cancer.
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| 34. |
- Bari, Sadia, et al.
(författare)
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Soft X-ray Spectroscopy as a Probe for Gas-Phase Protein Structure : Electron Impact Ionization from Within
- 2018
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539. ; 24:30, s. 7631-7636
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Tidskriftsartikel (refereegranskat)abstract
- Preservation of protein conformation upon transfer into the gas phase is key for structure determination of free single molecules, for example using X-ray free-electron lasers. In the gas phase, the helicity of melittin decreases strongly as the protein's protonation state increases. We demonstrate the sensitivity of soft X-ray spectroscopy to the gas-phase structure of melittin cations ([melittin+qH]q+, q=2-4) in a cryogenic linear radiofrequency ion trap. With increasing helicity, we observe a decrease of the dominating carbon 1s-π* transition in the amide C=O bonds for non-dissociative single ionization and an increase for non-dissociative double ionization. As the underlying mechanism we identify inelastic electron scattering. Using an independent atom model, we show that the more compact nature of the helical protein conformation substantially increases the probability for off-site intramolecular ionization by inelastic Auger electron scattering.
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| 35. |
- Bülow, Elinor, et al.
(författare)
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Sorting for storage in myeloid cells of nonmyeloid proteins and chimeras with the propeptide of myeloperoxidase precursor.
- 2002
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Ingår i: Journal of Leukocyte Biology. - 1938-3673. ; 71:2, s. 279-288
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Tidskriftsartikel (refereegranskat)abstract
- During formation of polymorphonuclear neutrophils, proteins are synthesized for storage in granules. Whereas sorting of proteins into distinct subtypes of cytoplasmic granules may reflect the coordinated expression of the proteins contained in them, still the mechanism(s) for the retrieval of proteins from the constitutive secretion is unknown. To investigate the mechanisms of retrieval, nonmyeloid secretory proteins were expressed in myeloid cell lines, and their subcellular fate was assessed. The contribution of the propeptide (MPOpro) of the myeloperoxidase (MPO) precursor was investigated by determining the fate of chimeras containing MPOpro. The nonmyeloid protein alpha(1)-microglobulin (alpha(1)-m) was targeted to storage organelles in 32D cells and colocalized with the lysosomal marker LAMP-1, whereas soluble TNF receptor 1 (sTNFR1) was secreted without granule targeting. Fusion of MPOpro to alpha(1)-m delayed exit from endoplasmic reticulum (ER), but subsequent targeting to dense organelles was indistinguishable from that of alpha(1)-m alone. Fusion proteins between MPOpro and sTNFR1 or green fluorescent protein expressed in myeloid 32D, K562, or PLB-985 cells did not associate stably with calreticulin or calnexin, molecular chaperones that normally interact transiently with the MPO precursor, but were still efficiently retained in the ER followed by degradation. We conclude that normally secreted, nonmyeloid proteins can be targeted efficiently to storage organelles in myeloid cells, that myeloid cells selectively target some proteins for storage but not others, and that MPOpro may contribute to the prolonged ER retention of the MPO precursor independent of the ER-molecular chaperones calreticulin and calnexin.
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| 36. |
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| 37. |
- Bulow, P., et al.
(författare)
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Long-term consequences of the reformation of psychiatric care : A 15-year follow-up study
- 2002
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Ingår i: Nordic Journal of Psychiatry. - : Informa UK Limited. - 0803-9488 .- 1502-4725. ; 56:1, s. 15-21
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Tidskriftsartikel (refereegranskat)abstract
- Although there are a great many epidemiological studies of psychiatric diseases and the outcomes of controlled rehabilitation programmes, there is a shortage of studies of routine psychiatric care. This study is a retrospective cohort study of the total number (n = 138) of patients receiving inpatient care at a psychiatric rehabilitation clinic in Jönköping during 1984. The follow-up period is 15 years, 1984-98. The group had a considerable amount of inpatient care, but this decreased dramatically during the time of investigation. Positive indications were that there were no suicides during the last 5 years of the period and that the number of registered crimes showed a marked decrease from 1992. Negative indications were low levels of work and occupation and few social contacts.
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| 38. |
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| 39. |
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| 40. |
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| 41. |
- Butler, Samuel J., et al.
(författare)
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Functionalization of Recombinant Amelogenin Nanospheres Allows Their Binding to Cellulose Materials
- 2016
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Ingår i: Biotechnology Journal. - : Wiley. - 1860-6768. ; 11:10, s. 1343-1351
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Tidskriftsartikel (refereegranskat)abstract
- Protein engineering to functionalize the self-assembling enamel matrix protein amelogenin with a cellulose binding domain (CBD) is used. The purpose is to examine the binding of the engineered protein, rh174CBD, to cellulose materials, and the possibility to immobilize self-assembled amelogenin nanospheres on cellulose. rh174CBD assembled to nanospheres ≈35 nm in hydrodynamic diameter, very similar in size to wild type amelogenin (rh174). Uniform particles are formed at pH 10 for both rh174 and rh174CBD, but only rh174CBD nanospheres showes significant binding to cellulose (Avicel). Cellulose binding of rh174CBD is promoted when the protein is self-assembled to nanospheres, compared to being in a monomeric form, suggesting a synergistic effect of the multiple CBDs on the nanospheres. The amount of bound rh174CBD nanospheres reached ≈15 mg/g Avicel, which corresponds to 4.2 to 6.3 × 10−7 mole/m2. By mixing rh174 and rh174CBD, and then inducing self-assembly, composite nanospheres with a high degree of cellulose binding can be formed, despite a lower proportion of rh174CBD. This demonstrates that amelogenin variants like rh174 can be incorporated into the nanospheres, and still retain most of the binding to cellulose. Engineered amelogenin nanoparticles can thus be utilized to construct a range of new cellulose based hybrid materials, e.g. for wound treatment.
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| 42. |
- Cnudde, Peter, 1970, et al.
(författare)
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Risk of further surgery on the same or opposite side and mortality after primary total hip arthroplasty: A multi-state analysis of 133,654 patients from the Swedish Hip Arthroplasty Register
- 2018
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Ingår i: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 1745-3682. ; 89:4, s. 386-393
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose - The hip-related timeline of patients following a total hip arthroplasty (THA) can vary. Ideally patients will live their life without need for further surgery; however, some will undergo replacement on the contralateral hip and/or reoperations. We analyzed the probability of mortality and further hip-related surgery on the same or contralateral hip. Patients and methods - We performed a multi-state survival analysis on a prospectively followed cohort of 133,654 Swedish patients undergoing an elective THA between 1999 and 2012. The study used longitudinally collected information from the Swedish Hip Arthroplasty Register and administrative databases. The analysis considered the patients' sex, age, prosthesis type, surgical approach, diagnosis, comorbidities, education, and civil status. Results - During the study period patients were twice as likely to have their contralateral hip replaced than to die. However, with passing time, probabilities converged and for a patient who only had 1 non-revised THA at 10 years, there was an equal chance of receiving a second THA and dying (24%). It was 8 times more likely that the second hip would become operated with a primary THA than that the first hip would be revised. Multivariable regression analysis reinforced the influence of age at operation, sex, diagnosis, comorbidity, and socioeconomic status influencing state transition. Interpretation - Multi-state analysis can provide a comprehensive model of further states and transition probabilities after an elective THA. Information regarding the lifetime risk for bilateral surgery, revision, and death can be of value when discussing the future possible outcomes with patients, in healthcare planning, and for the healthcare, economy.
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| 43. |
- Cnudde, Peter, 1970, et al.
(författare)
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Trends in the patient demographics, socio-economic characteristics, surgical factors and outcomes between 1999 and 2012
- 2017
-
Ingår i: Orthopaedic Proceedings. 99-B (SUPP 12). - : British Editorial Society of Bone & Joint Surgery. - 1358-992X .- 2049-4416.
-
Konferensbidrag (refereegranskat)abstract
- Prospectively collected data is an important source of information subjected to change over time. What surgeons were doing in 1999 might not be the case anymore in 2016 and this change in time also applies to a number of factors related to the performance and outcome of total hip replacement. We evaluated the evolution of factors related to the patient, the surgical procedure, socio-economy and various outcome parameters after merging the databases of the Swedish Hip Arthroplasty Register, Statistics Sweden and the National Board of Health and Welfare. Data on 193,253 THRs (164,113 patients) operated between 1999 and 2012 were merged with databases including general information about the Swedish population and about hospital care. We studied the evolution of surgical volume, patient demographics, socio-economic factors, surgical factors, length of stay, mortality rate, adverse events, re-operation and revision rates and PROMs. Most patients were operated because of primary osteoarthritis and this share increased further during the period at the expense of decreasing number of patients with inflammatory OA and hip fracture. Comorbidity and ASA scores increased for each year. The share of all cemented implants has dropped from 92% to 68% with a corresponding increase of all uncemented from 2% to 16%. Length of stay decreased with about 50 percent to 4.5 days in 2012. The 30- and 90-day mortality rate dropped to 0.4% and 0.7%. Re-operation and revision rates at 2 years were lower in the more recent years. The postoperative PROMs are improving despite the preoperative pain scores getting worse. Even in Sweden, always been considered as a very conservative country with regards to hip replacement surgery, the demographics of the patients, the comorbidities and the primary diagnosis for surgery are changing. Despite these changes the outcomes like mortality, re-operations, revisions and PROMs are improving.
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| 44. |
- Cooper, Chris E., et al.
(författare)
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Engineering tyrosine residues into hemoglobin enhances heme reduction, decreases oxidative stress and increases vascular retention of a hemoglobin based blood substitute
- 2019
-
Ingår i: Free Radical Biology and Medicine. - : Elsevier BV. - 0891-5849. ; 134, s. 106-118
-
Tidskriftsartikel (refereegranskat)abstract
- Hemoglobin (Hb)-based oxygen carriers (HBOC) are modified extracellular proteins, designed to replace or augment the oxygen-carrying capacity of erythrocytes. However, clinical results have generally been disappointing due to adverse side effects, in part linked to the intrinsic oxidative toxicity of Hb. Previously a redox-active tyrosine residue was engineered into the Hb β subunit (βF41Y) to facilitate electron transfer between endogenous antioxidants such as ascorbate and the oxidative ferryl heme species, converting the highly oxidizing ferryl species into the less reactive ferric (met) form. We inserted different single tyrosine mutations into the α and β subunits of Hb to determine if this effect of βF41Y was unique. Every mutation that was inserted within electron transfer range of the protein surface and the heme increased the rate of ferryl reduction. However, surprisingly, three of the mutations (βT84Y, αL91Y and βF85Y) also increased the rate of ascorbate reduction of ferric(met) Hb to ferrous(oxy) Hb. The rate enhancement was most evident at ascorbate concentrations equivalent to that found in plasma (< 100 μM), suggesting that it might be of benefit in decreasing oxidative stress in vivo. The most promising mutant (βT84Y) was stable with no increase in autoxidation or heme loss. A decrease in membrane damage following Hb addition to HEK cells correlated with the ability of βT84Y to maintain the protein in its oxygenated form. When PEGylated and injected into mice, βT84Y was shown to have an increased vascular half time compared to wild type PEGylated Hb. βT84Y represents a new class of mutations with the ability to enhance reduction of both ferryl and ferric Hb, and thus has potential to decrease adverse side effects as one component of a final HBOC product.
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| 45. |
- Couto, Rafael Carvalho, et al.
(författare)
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Breaking inversion symmetry by protonation : Experimental and theoretical NEXAFS study of the diazynium ion, N2H
- 2021
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 23:32, s. 17166-17176
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Tidskriftsartikel (refereegranskat)abstract
- As an example of symmetry breaking in NEXAFS spectra of protonated species we present a high resolution NEXAFS spectrum of protonated dinitrogen, the diazynium ion N2H+. By ab initio calculations we show that the spectrum consists of a superposition of two nitrogen 1s absorption spectra, each including a π∗ band, and a nitrogen 1s to H+ charge transfer band followed by a weak irregular progression of high energy excitations. Calculations also show that, as an effect of symmetry breaking by protonation, the π∗ transitions are separated by 0.23 eV, only slightly exceeding the difference in the corresponding dark (symmetry forbidden) and bright (symmetry allowed) core excitations of neutral N2. By DFT and calculations and vibrational analysis, the complex π∗ excitation band of N2H+ is understood as due to the superposition of the significantly different vibrational progressions of excitations from terminal and central nitrogen atoms, both leading to bent final state geometries. We also show computationally that the electronic structure of the charge transfer excitation smoothly depends on the nitrogen-proton distance and that there is a clear extension of the spectra going from infinity to close nitrogen-proton distance where fine structures show some, although not fully detailed, similarities. An interesting feature of partial localization of the nitrogen core orbitals, with a strong, non-monotonous, variation with nitrogen-proton distance could be highlighted. Specific effects could be unraveled when comparing molecular cation NEXAFS spectra, as represented by recently recorded spectra of N2+ and CO+, and spectra of protonated molecules as represented here by the N2H+ ion. Both types containing rich physical effects not represented in NEXAFS of neutral molecules because of the positive charge, whereas protonation also breaks the symmetry. The effect of the protonation on dinitrogen can be separated in charge, which extends the high-energy part of the spectrum, and symmetry-breaking, which is most clearly seen in the low-energy π∗ transition.
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| 46. |
- Couto, Rafael Carvalho, et al.
(författare)
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The carbon and oxygen K-edge NEXAFS spectra of CO
- 2020
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 22:28, s. 16215-16223
-
Tidskriftsartikel (refereegranskat)abstract
- We present and analyze high resolution near edge X-ray absorption fine structure (NEXAFS) spectra of CO+ at the carbon and oxygen K-edges. The spectra show a wealth of features that appear very differently at the two K-edges. The analysis of these features can be divided into three parts; (i) repopulation transition to the open shell orbital – here the C(1s) or O(1s) to 5σ transition, where the normal core hole state is reached from a different initial state and different interaction than in X-ray photoelectron spectroscopy; (ii) spin coupled split valence bands corresponding to C(1s) or O(1s) to π* transitions; (iii) remainder weak and long progressions towards the double ionization potentials containing a manifold of peaks. These parts, none of which has correspondence in NEXAFS spectra of neutral molecules, are dictated by the localization of the singly occupied 5σ orbital, adding a dimension of chemistry to the ionic NEXAFS technique.
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| 47. |
- Delcey, Mickael G, 1988-, et al.
(författare)
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Soft X-ray signatures of cationic manganese–oxo systems, including a high-spin manganese(v) complex
- 2022
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 24:6, s. 3598-3610
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Tidskriftsartikel (refereegranskat)abstract
- Limitations in synthesis of high-valent metal–oxo complexes are circumvented by trapping a series of ionic Mn–oxo complexes. One of them is a rare high-spin Mn(v)–oxo, which can serve as a template to identify similar intermediates in catalysis.
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| 48. |
- Egorov, Dmitrii, et al.
(författare)
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Near-Edge Soft X-ray Absorption Mass Spectrometry of Protonated Melittin
- 2018
-
Ingår i: Journal of the American Society for Mass Spectrometry. - : American Chemical Society (ACS). - 1044-0305. ; 29:11, s. 2138-2151
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated the photoionization and photofragmentation yields of gas-phase multiply protonated melittin cations for photon energies at the K-shell absorption edges of carbon, nitrogen, and oxygen. Two similar experimental approaches were employed. In both experiments, mass selected [melittin+qH]q+ (q=2–4) ions were accumulated in radiofrequency ion traps. The trap content was exposed to intense beams of monochromatic soft X-ray photons from synchrotron beamlines and photoproducts were analyzed by means of time-of-flight mass spectrometry. Mass spectra were recorded for fixed photon energies, and partial ion yield spectra were recorded as a function of photon energy. The combination of mass spectrometry and soft X-ray spectroscopy allows for a direct correlation of protein electronic structure with various photoionization channels. Non-dissociative single and double ionization are used as a reference. The contribution of both channels to various backbone scission channels is quantified and related to activation energies and protonation sites. Soft X-ray absorption mass spectrometry combines fast energy deposition with single and double ionization and could complement established activation techniques. [Figure not available: see fulltext.].
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| 49. |
- Eriksson, Nélida Leiva, et al.
(författare)
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Sugar beet hemoglobins : Reactions with nitric oxide and nitrite reveal differential roles for nitrogen metabolism
- 2019
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Ingår i: Biochemical Journal. - 0264-6021. ; 476:14, s. 2111-2125
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Tidskriftsartikel (refereegranskat)abstract
- In contrast with human hemoglobin (Hb) in red blood cells, plant Hbs do not transport oxygen, instead research points towards nitrogen metabolism. Using comprehensive and integrated biophysical methods we characterized three sugar beet Hbs: BvHb1.1, BvHb1.2 and BvHb2. Their affinities for oxygen, CO, and hexacoordination were determined. Their role in nitrogen metabolism was studied by assessing their ability to bind NO, to reduce nitrite (NiR, nitrite reductase), and to form nitrate (NOD, NO dioxygenase). Results show that BvHb1.2 has high NOD-like activity, in agreement with the high nitrate levels found in seeds where this protein is expressed. BvHb1.1, on the other side, is equally capable to bind NO as to form nitrate, its main role would be to protect chloroplasts from the deleterious effects of NO. Finally, the ubiquitous, reactive, and versatile BvHb2, able to adopt ‘open and closed forms’, would be part of metabolic pathways where the balance between oxygen and NO is essential. For all proteins, the NiR activity is relevant only when nitrite is present at high concentrations and both NO and oxygen are absent. The three proteins have distinct intrinsic capabilities to react with NO, oxygen and nitrite; however, it is their concentration which will determine the BvHbs’ activity.
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| 50. |
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