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Sökning: WFRF:(Näslund I)

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1.
  • Ahlin, Sofie, 1985, et al. (författare)
  • Fracture risk after three bariatric surgery procedures in Swedish obese subjects : up to 26 years follow-up of a controlled intervention study
  • 2020
  • Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 287:5, s. 546-557
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Previous studies have reported an increased fracture risk after bariatric surgery. Objective: To investigate the association between different bariatric surgery procedures and fracture risk. Methods: Incidence rates and hazard ratios for fracture events were analysed in the Swedish Obese Subjects study; an ongoing, nonrandomized, prospective, controlled intervention study. Hazard ratios were adjusted for risk factors for osteoporosis and year of inclusion. Information on fracture events were captured from the Swedish National Patient Register. The current analysis includes 2007 patients treated with bariatric surgery (13.3% gastric bypass, 18.7% gastric banding, and 68.0% vertical banded gastroplasty) and 2040 control patients with obesity matched on group level based on 18 variables. Median follow-up was between 15.1 and 17.9 years for the different treatment groups. Results: During follow-up, the highest incidence rate for first-time fracture was observed in the gastric bypass group (22.9 per 1000 person-years). The corresponding incidence rates were 10.4, 10.7 and 9.3 per 1000 person-years for the vertical banded gastroplasty, gastric banding and control groups, respectively. The risk of fracture was increased in the gastric bypass group compared with the control group (adjusted hazard ratio [adjHR] 2.58; 95% confidence interval [CI] 2.02–3.31; P < 0.001), the gastric banding group (adjHR 1.99; 95%CI 1.41–2.82; P < 0.001), and the vertical banded gastroplasty group (adjHR 2.15; 95% CI 1.66–2.79; P < 0.001). Conclusions: The risk of fracture is increased after gastric bypass surgery. Our findings highlight the need for long-term follow-up of bone health for patients undergoing this treatment.
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  • Rydén, Mikael, et al. (författare)
  • Lipolysis defect in people with obesity who undergo metabolic surgery
  • 2022
  • Ingår i: Journal of Internal Medicine. - : Wiley-Blackwell Publishing Inc.. - 0954-6820 .- 1365-2796. ; 292:4, s. 667-678
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: Cross-sectional studies demonstrate that catecholamine stimulation of fat cell lipolysis is blunted in obesity. We investigated whether this defect persists after substantial weight loss has been induced by metabolic surgery, and whether it is related to the outcome.DESIGN/METHODS: Patients with obesity not able to successfully reduce body weight by conventional means (n = 126) were investigated before and 5 years after Roux-en-Y gastric bypass surgery (RYGB). They were compared with propensity-score matched subjects selected from a control group (n = 1017), and with the entire group after adjustment for age, sex, body mass index (BMI), fat cell volume and other clinical parameters. Catecholamine-stimulated lipolysis (glycerol release) was investigated in isolated fat cells using noradrenaline (natural hormone) or isoprenaline (synthetic beta-adrenoceptor agonist).RESULTS: Following RYGB, BMI was reduced from 39.9 (37.5-43.5) (median and interquartile range) to 29.5 (26.7-31.9) kg/m2 (p < 0.0001). The post-RYGB patients had about 50% lower lipolysis rates compared with the matched and total series of controls (p < 0.0005). Nordrenaline activation of lipolysis at baseline was associated with the RYGB effect; those with high lipolysis activation (upper tertile) lost 30%-45% more in body weight, BMI or fat mass than those with low (bottom tertile) initial lipolysis activation (p < 0.0007).CONCLUSION: Patients with obesity requiring metabolic surgery have impaired ability of catecholamines to stimulate lipolysis, which remains despite long-term normalization of body weight by RYGB. Furthermore, preoperative variations in the ability of catecholamines to activate lipolysis may predict the long-term reduction in body weight and fat mass.
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6.
  • Teneberg, Susanne, et al. (författare)
  • Lactotetraosylceramide, a novel glycosphingolipid receptor for Helicobacter pylori, present in human gastric epithelium
  • 2002
  • Ingår i: Journal of Biological Chemistry. - Bethesda : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 277:22, s. 19709-19719
  • Tidskriftsartikel (refereegranskat)abstract
    • The binding of Helicobacter pylori to glycosphingolipids was examined by binding of 35S-labeled bacteria to glycosphingolipids on thin-layer chromatograms. In addition to previously reported binding specificities, a selective binding to a non-acid tetraglycosylceramide of human meconium was found. This H. pylori binding glycosphingolipid was isolated and, on the basis of mass spectrometry, proton NMR spectroscopy, and degradation studies, were identified as Galβ3GlcNAcβ3-Galβ4Glcβ1Cer (lactotetraosylceramide). When using non-acid glycosphingolipid preparations from human gastric epithelial cells, an identical binding of H. pylori to the tetraglycosylceramide interval was obtained in one of seven samples. Evidence for the presence of lactotetraosylceramide in the binding-active interval was obtained by proton NMR spectroscopy of intact glycosphingolipids and by gas chromatography-electron ionization mass spectrometry of permethylated tetrasaccharides obtained by ceramide glycanase hydrolysis. The lactotetraosylceramide binding property was detected in 65 of 74 H. pylori isolates (88%) Binding of H. pylori to lactotetraosylceramide on thin-layer chromatograms was inhibited by preincubation with lactotetraose but not with lactose. Removal of the terminal galactose of lactotetraosylceramide by galactosidase hydrolysis abolished the binding as did hydrazinolysis of the acetamido group of the N-acetylglucosamine. Therefore, Galβ3GlcNAc is an essential part of the binding epitope.
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  • Anveden, Åsa, et al. (författare)
  • Long-term incidence of gallstone disease after bariatric surgery: results from the nonrandomized controlled Swedish Obese Subjects study
  • 2020
  • Ingår i: Surgery for Obesity and Related Diseases. - : Elsevier BV. - 1550-7289. ; 16:10, s. 1474-1482
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Gallstone disease is a known short-term complication of bariatric surgery; little is known of the long-term incidence. Objectives: The aim of this study was to investigate the association between bariatric surgery and long-term incidence of gallstone disease. Settings: A total of 25 surgery departments and 480 primary healthcare centers in Sweden. Methods: The Swedish Obese Subjects study is a prospective, controlled study comparing the effects of bariatric surgery with usual care with a follow-up of 20 years, including 4047 individuals. The current report includes all participants without previous or concomitant cholecystectomy (n = 3597). Operative techniques used in the surgery group (n = 1755) were gastric bypass (n = 236), vertical banded gastroplasty (n = 1202), and gastric banding (n = 317). The control group (n = 1842) received customary treatment for obesity. Gallstone disease was a predefined secondary endpoint in the Swedish Obese Subjects study and the primary endpoint of this report. Data were obtained by cross-checking our study database with the Swedish National Patient Register of diagnosis and procedures. Results: In the surgery and control groups, respectively, there were 307 and 252 first-time events of symptomatic gallstone disease and 230 and 170 cholecystectomies (log-rank P <.001, both outcomes). Bariatric surgery was associated with an increased risk of symptomatic gallstone disease, with a more pronounced risk during the first years of follow-up (P =.002) and an increased risk for cholecystectomy but with no time-varying effect (P =.213). Conclusions: Bariatric surgery increases the risk for symptomatic gallstone disease and cholecystectomy, especially during the first years following treatment. © 2020 American Society for Bariatric Surgery
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8.
  • Axelsson, K. F., et al. (författare)
  • Fracture Risk After Gastric Bypass Surgery : A Retrospective Cohort Study
  • 2018
  • Ingår i: Osteoporosis International. - : Springer London. - 0937-941X .- 1433-2965. ; 29:Suppl. 1, s. S491-S491
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Objectives: Gastric bypass surgery constitutes the most common and effective bariatric surgery to treat obesity. Gastric bypass leads to bone oss but fracture risk following surgery has been insufficiently studied. Our objective was to investigate if gastric bypass surgery in obese patients, with and without diabetes, was associated with fracture risk, and if the fracture risk was associated with post-surgery weight loss or insufficient calcium and vitamin D supplementation.Methods: Using large databases, 38 971 obese patients undergoing gastric bypass were identified, 7758 with diabetes and 31 213 without. Through multivariable 1:1 propensity score matching, well-balanced controls were identified. The risk of fracture and fall injury was investigated using Cox proportional hazards and flexible parameter models. Fracture risk according to weight loss and degree of calcium and vitamin D supplementation one year post-surgery was investigated.Results: 77 942 patients had a median and total follow-up time of 3.1 (IQR 1.7-4.6) and 251 310 person-years, respectively. Gastric bypass was associated with increased risk of any fracture, in patients with diabetes and without diabetes using a multivariable Cox model (HR 1.26, 95%CI 1.05-1.53 and HR 1.32, 95%CI 1.18-1.47, respectively). The risk of fall injury without fracture was also increased after gastric bypass, both in patients with (HR 1.26 95%CI 1.04-1.52) and without diabetes (HR 1.24 95%CI 1.12-1.38). Weight loss or degree of calcium and vitamin D supplementation after gastric bypass were not associated with fracture risk.Conclusions: Gastric bypass was associated with an increased risk of fracture and fall injury. Weight loss or calcium and vitamin D supplementation following surgery were not associated with fracture risk. These findings indicate that gastric bypass increases fracture risk, which could at least partly be due to increased susceptibility to falls.
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  • Axer, S., et al. (författare)
  • NON-RESPONSE AFTER GASTRIC BYPASS AND SLEEVE GASTRECTOMY - THE THEORETICAL NEED FOR REVISIONAL BARIATRIC SURGERY RESULTS FROM THE SCANDINAVIAN OBESITY SURGERY REGISTRY : Revisional surgery
  • 2022
  • Ingår i: Obesity Surgery. - : Springer. - 0960-8923 .- 1708-0428. ; 32:Suppl. 2, s. 381-381
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Background: Revisional surgery is a second-line treatment option after sleeve gastrectomy (SG) and gastric bypass (GBP) in patients with primary or secondary non-response. This study is an analysis of the theoretical need for revisional surgery when applying four indication benchmarks.Objective: The aim was to analyze the risk for primary and secondary non-response after SG and GBP.Setting: 44 hospitals in Sweden.Methods: Based on data from the Scandinavian Obesity Surgery Registry, SG and GBP were compared regarding four endpoints: 1. Excess Weight Loss (%EWL) < 50%; 2. weight regain of more than 10 kg after nadir; 3. fulfillment of IFSO-guidelines; or 4. ADA-criteria for bariatric surgery two years after primary surgery.Results: 60 426 individuals were included in the study (SG: n=7856 and GBP: n=52 570). Compared to patients in the GBP-group, more SG patients failed to achieved a %EWL > 50% (23.0% versus 8.5%, p < .001), regained more than 10 kg after nadir (4.3% versus 2.5%, p < .001), more often fulfilled the IFSO-criteria (8.0% vs. 4.5%, p < .001) or the ADA criteria (3.3% vs. 1.8%, p < 001) for bariatric/metabolic surgery at the 2-year follow-up.Conclusions: SG is associated with a higher risk for primary and secondary non-response compared to gastric bypass. To offer revisional bariatric surgery to all non-responders exceeds the bounds of feasibility and operability. Hence, individual prioritization and intensified evaluation of alternative second-line treatments is necessary.
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  • Chen, Hao Yu, et al. (författare)
  • Association of FADS1/2 Locus Variants and Polyunsaturated Fatty Acids With Aortic Stenosis
  • 2020
  • Ingår i: JAMA cardiology. - : American Medical Association (AMA). - 2380-6583 .- 2380-6591. ; 5:6, s. 694-702
  • Tidskriftsartikel (refereegranskat)abstract
    • Importance: Aortic stenosis (AS) has no approved medical treatment. Identifying etiological pathways for AS could identify pharmacological targets.Objective: To identify novel genetic loci and pathways associated with AS.Design, Setting, and Participants: This genome-wide association study used a case-control design to evaluate 44 703 participants (3469 cases of AS) of self-reported European ancestry from the Genetic Epidemiology Research on Adult Health and Aging (GERA) cohort (from January 1, 1996, to December 31, 2015). Replication was performed in 7 other cohorts totaling 256 926 participants (5926 cases of AS), with additional analyses performed in 6942 participants from the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium. Follow-up biomarker analyses with aortic valve calcium (AVC) were also performed. Data were analyzed from May 1, 2017, to December 5, 2019.Exposures: Genetic variants (615 643 variants) and polyunsaturated fatty acids (ω-6 and ω-3) measured in blood samples.Main Outcomes and Measures: Aortic stenosis and aortic valve replacement defined by electronic health records, surgical records, or echocardiography and the presence of AVC measured by computed tomography.Results: The mean (SD) age of the 44 703 GERA participants was 69.7 (8.4) years, and 22 019 (49.3%) were men. The rs174547 variant at the FADS1/2 locus was associated with AS (odds ratio [OR] per C allele, 0.88; 95% CI, 0.83-0.93; P = 3.0 × 10-6), with genome-wide significance after meta-analysis with 7 replication cohorts totaling 312 118 individuals (9395 cases of AS) (OR, 0.91; 95% CI, 0.88-0.94; P = 2.5 × 10-8). A consistent association with AVC was also observed (OR, 0.91; 95% CI, 0.83-0.99; P = .03). A higher ratio of arachidonic acid to linoleic acid was associated with AVC (OR per SD of the natural logarithm, 1.19; 95% CI, 1.09-1.30; P = 6.6 × 10-5). In mendelian randomization, increased FADS1 liver expression and arachidonic acid were associated with AS (OR per unit of normalized expression, 1.31 [95% CI, 1.17-1.48; P = 7.4 × 10-6]; OR per 5-percentage point increase in arachidonic acid for AVC, 1.23 [95% CI, 1.01-1.49; P = .04]; OR per 5-percentage point increase in arachidonic acid for AS, 1.08 [95% CI, 1.04-1.13; P = 4.1 × 10-4]).Conclusions and Relevance: Variation at the FADS1/2 locus was associated with AS and AVC. Findings from biomarker measurements and mendelian randomization appear to link ω-6 fatty acid biosynthesis to AS, which may represent a therapeutic target.
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12.
  • Chen, H.Y., et al. (författare)
  • Dyslipidemia, inflammation, calcification, and adiposity in aortic stenosis: a genome-wide study
  • 2023
  • Ingår i: European Heart Journal. - : Oxford University Press. - 0195-668X .- 1522-9645. ; 44:21, s. 1927-1939
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims Although highly heritable, the genetic etiology of calcific aortic stenosis (AS) remains incompletely understood. The aim of this study was to discover novel genetic contributors to AS and to integrate functional, expression, and cross-phenotype data to identify mechanisms of AS. Methods and results A genome-wide meta-analysis of 11.6 million variants in 10 cohorts involving 653 867 European ancestry participants (13 765 cases) was performed. Seventeen loci were associated with AS at P ≤ 5 × 10−8, of which 15 replicated in an independent cohort of 90 828 participants (7111 cases), including CELSR2–SORT1, NLRP6, and SMC2. A genetic risk score comprised of the index variants was associated with AS [odds ratio (OR) per standard deviation, 1.31; 95% confidence interval (CI), 1.26–1.35; P = 2.7 × 10−51] and aortic valve calcium (OR per standard deviation, 1.22; 95% CI, 1.08–1.37; P = 1.4 × 10−3), after adjustment for known risk factors. A phenome-wide association study indicated multiple associations with coronary artery disease, apolipoprotein B, and triglycerides. Mendelian randomization supported a causal role for apolipoprotein B-containing lipoprotein particles in AS (OR per g/L of apolipoprotein B, 3.85; 95% CI, 2.90–5.12; P = 2.1 × 10−20) and replicated previous findings of causality for lipoprotein(a) (OR per natural logarithm, 1.20; 95% CI, 1.17–1.23; P = 4.8 × 10−73) and body mass index (OR per kg/m2, 1.07; 95% CI, 1.05–1.9; P = 1.9 × 10−12). Colocalization analyses using the GTEx database identified a role for differential expression of the genes LPA, SORT1, ACTR2, NOTCH4, IL6R, and FADS. Conclusion Dyslipidemia, inflammation, calcification, and adiposity play important roles in the etiology of AS, implicating novel treatments and prevention strategies. © The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.
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  • Gagnon, J, et al. (författare)
  • DNA polymorphism in the uncoupling protein 1 (UCP1) gene has no effect on obesity related phenotypes in the Swedish Obese Subjects cohorts
  • 1998
  • Ingår i: International Journal of Obesity. ; 22, s. 500-505
  • Tidskriftsartikel (refereegranskat)abstract
    • Physical Activity Sciences Laboratory, Laval University, Ste-Foy, Quebec, Canada. OBJECTIVE: To investigate the relationships between the A-G point mutation at position -3826 bp in the 5' flanking domain of the uncoupling protein 1 (UCP1 A-3826G) and some obesity phenotypes in the Swedish Obese Subjects (SOS) cohorts of obese and non-obese men and women. Previous studies have supported the hypothesis of an association between the UCP1 A-3826G polymorphism and body weight regulation in humans. DESIGN: Case-control study comparing obese subjects from the SOS registry and a sample of the Swedish general population (body mass index (BMI) <27 kg/m2) with respect to genotype and allele frequencies of the UCP1 A-3826G polymorphism. SUBJECTS: A total of 985 Swedish subjects including 674 obese (310 Male; 364 Female) and 311 non-obese subjects (54 Male; 257 Female) from the SOS cohorts. MEASUREMENTS: DNA was extracted from total blood and genotyped by PCR-RFLP. Obesity-related phenotypes include weight history for SOS obese cohort and current weight, BMI, waist circumference and waist to hip ratio (WHR) for obese and normal weight subjects. RESULTS: No significant difference in the allelic frequencies between obese and non-obese subjects (0.25 vs 0.24; P = 0.67). In both genders, current weight, BMI, waist circumference, WHR and weight gain over time (either measures of maximal weight ever achieved minus weight at 20 y or current weight minus weight at 20 y) were similar in carriers and non-carriers of the UCP1 A-3826G mutation (P>0.05). Similar results were obtained when the three genotypes were compared. CONCLUSIONS: In contrast to what was found in other populations, the UCP1 A-3826G sequence variation is not associated with obesity-related phenotypes and weight gain over time in subjects from the SOS cohorts. PMID: 9665669 [PubMed - indexed for MEDLINE]
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15.
  • Höskuldsdottir, G., et al. (författare)
  • Effects of bariatric surgery on the incidence of heart failure and atrial fibrillation in patients with type 2 diabetes and obesity
  • 2020
  • Ingår i: Diabetologia. - : Springer. - 0012-186X .- 1432-0428. ; 63:Suppl. 1, s. S262-S262
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Background and aims: To study the effects of obesity treatment with gastric bypass surgery on hospitalization for heart failure (HF) and atrial fibrillation (AF) in patients with type 2 diabetes (T2D) and obesity. We also studied the effects of gastric bypass surgery on mortality in a subgroup of individuals with preexisting heart failure.Materials and methods: In this register-based nationwide cohort study we compared individuals with T2D and obesity that underwent Roux-en-Y gastric bypass surgery (RYGB) with matched individuals with T2D and obesity that did not undergo surgery. Data was gathered by linking the Swedish National Diabetes Register and Scandinavian Obesity Surgery Registry. Matching of individuals for age, gender, BMI and calendar time was done using a time updated propensity score. The main outcome measures were hospitalization for HF and/or AF, and mortality in patients with preexisting HF. The risk for heart failure, AF and death were assessed using a Cox-proportional hazards regression model that addressed measured confounding.Results: We identified 5321 individuals with T2D and obesity that had undergone RYGB between January 2007 and December 2013 and 5321 matched controls. The individuals includedwere between 18 and 65 years old and had a BMI > 27.5 kg/m2. The follow-up time for hospitalization was until the end of 2015 (mean 4.5 years) and the end of 2016 for death. Our results show a 73% lower risk for HF (HR 0.27 (0.19, 0.38) p<0.001), 41% for AF (HF 0.59 (0.44, 0.78) p < 0.001), and 77% for concomitant AF and HF (HR0.23 (0.12, 0.46) p < 0.001) in the surgically treated group. In patients with preexisting HF we observed significantly lower mortality in the group that underwent surgery (HR0.23 (0.12, 0.43) p < 0.001).Conclusion: Bariatric surgery may reduce risk for HF and AF in patients with T2D and obesity, speculatively via positive cardiovascular and renal effects. Obesity treatment with surgery may also be a valuable alternative in selected patients with T2D and HF.
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  • Islim, Abdurrahman I, et al. (författare)
  • External validation and recalibration of an incidental meningioma prognostic model - IMPACT: protocol for an international multicentre retrospective cohort study.
  • 2022
  • Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 12:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Due to the increased use of CT and MRI, the prevalence of incidental findings on brain scans is increasing. Meningioma, the most common primary brain tumour, is a frequently encountered incidental finding, with an estimated prevalence of 3/1000. The management of incidental meningioma varies widely with active clinical-radiological monitoring being the most accepted method by clinicians. Duration of monitoring and time intervals for assessment, however, are not well defined. To this end, we have recently developed a statistical model of progression risk based on single-centre retrospective data. The model Incidental Meningioma: Prognostic Analysis Using Patient Comorbidity and MRI Tests (IMPACT) employs baseline clinical and imaging features to categorise the patient with an incidental meningioma into one of three risk groups: low, medium and high risk with a proposed active monitoring strategy based on the risk and temporal trajectory of progression, accounting for actuarial life expectancy. The primary aim of this study is to assess the external validity of this model.IMPACT is a retrospective multicentre study which will aim to include 1500 patients with an incidental intracranial meningioma, powered to detect a 10% progression risk. Adult patients ≥16 years diagnosed with an incidental meningioma between 1 January 2009 and 31 December 2010 will be included. Clinical and radiological data will be collected longitudinally until the patient reaches one of the study endpoints: intervention (surgery, stereotactic radiosurgery or fractionated radiotherapy), mortality or last date of follow-up. Data will be uploaded to an online Research Electronic Data Capture database with no unique identifiers. External validity of IMPACT will be tested using established statistical methods.Local institutional approval at each participating centre will be required. Results of the study will be reported through peer-reviewed articles and conferences and disseminated to participating centres, patients and the public using social media.
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17.
  • Johnsson, Jörgen I, 1959, et al. (författare)
  • Environmental effects on behavioural development: consequences for fitness of captive-reared fishes in the wild
  • 2014
  • Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 85, s. 1946-1971
  • Tidskriftsartikel (refereegranskat)abstract
    • Why do captive-reared fishes generally have lower fitness in natural environments than wild conspecifics, even when the hatchery fishes are derived from wild parents from the local population? A thorough understanding of this question is the key to design artificial rearing environments that optimize post-release performance, as well as to recognize the limitations of what can be achieved by modifying hatchery rearing methods. Fishes are generally very plastic in their development and through gene–environment interactions, epigenetic and maternal effects their phenotypes will develop differently depending on their rearing environment. This suggests that there is scope for modifying conventional rearing environments to better prepare fishes for release into the wild. The complexity of the natural environment is impossible to mimic in full-scale rearing facilities. So, in reality, the challenge is to identify key modifications of the artificial rearing environment that are practically and economically feasible and that efficiently promote development towards a more wild-like phenotype. Do such key modifications really exist? Here, attempts to use physical enrichment and density reduction to improve the performance of hatchery fishes are discussed and evaluated. These manipulations show potential to increase the fitness of hatchery fishes released into natural environments, but the success is strongly dependent on adequately adapting methods to species and life stage-specific conditions.
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18.
  • Johnsson, Jörgen I, 1959, et al. (författare)
  • Studying behavioural variation in salmonids from an ecological perspective: observations questions methodological considerations
  • 2018
  • Ingår i: Reviews in Fish Biology and Fisheries. - : Springer Science and Business Media LLC. - 0960-3166 .- 1573-5184. ; 28:4, s. 795-823
  • Tidskriftsartikel (refereegranskat)abstract
    • Salmonid fish are an ecologically important and extensively studied group of fish which concern many interest groups in our society. The aim of this paper is to discuss and suggest solutions to the multifaceted problems associated with studying behavioural variation in salmonids, with focus on designing behavioural studies that are ecologically relevant. Many of the general problems and solutions discussed can be applied to other animals as well. First, the importance of asking clear questions when conceiving behavioural studies is addressed, using Tinbergen's four questions and associated theories as stepping stones towards generating testable hypotheses about behavioural variation. We then address a range of methodological challenges encountered when attempting to study behavioural variation in salmonids and suggest solutions to overcome these problems. A range of approaches is discussed, from highly controllable laboratory experiments to monitoring studies of behaviour in the wild. The importance of combining lab- and field approaches to evaluate the ecological relevance of behavioural variation is highlighted. Finally, we suggest a general framework using a multi-faceted research approach to address questions about the behavioural ecology of salmonids (and other animals) so that knowledge can progress, and the ecological relevance of behavioural studies can be validated. BOTT JC, 1989, BEHAVIOUR, V108, P104
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19.
  • Klockhoff, H, et al. (författare)
  • Faster absorption of ethanol and higher peak concentration in women after gastric bypass surgery
  • 2002
  • Ingår i: British Journal of Clinical Pharmacology. - : Wiley. - 0306-5251 .- 1365-2125. ; 54:6, s. 587-591
  • Tidskriftsartikel (refereegranskat)abstract
    • Aims: To investigate the absorption, distribution and elimination of ethanol in women with abnormal gut as a result of gastric bypass surgery. Patients who undergo gastric bypass for morbid obesity complain of increased sensitivity to the effects of alcohol after the operation. Methods: Twelve healthy women operated for morbid obesity at least 3 years earlier were recruited. Twelve other women closely matched in terms of age and body mass index (BMI) served as the control group. After an overnight fast each subject drank 95% v/v ethanol (0.30 g kg-1 body weight) as a bolus dose. The ethanol was diluted with orange juice to 20% v/v and finished in 5 min. Specimens of venous blood were taken from an indwelling catheter before drinking started and every 10 min for up to 3.5 h post-dosing. The blood alcohol concentration (BAC) was determined by headspace gas chromatography. Results: The maximum blood-ethanol concentration (Cmax) was 0.741 ▒ 0.211 g l-1 (▒ s.d.) in the operated group compared with 0.577 ▒ 0.112 g l-1 in the controls (mean difference 0.164 g l-1, 95% confidence interval (CI) 0.021, 0.307). The median time to peak (tmax) was 10 min in the bypass patients compared with 30 min in controls (median difference -15 min (95% CI -10, -20 min). At 10 and 20 min post-dosing the BAC was higher in the bypass patients (P < 0.05) but not at 30 min and all later times (P > 0.05). Other pharmacokinetic parameters of ethanol were not significantly different between the two groups of women (P > 0.05). Conclusions: The higher sensitivity to ethanol after gastric bypass surgery probably reflects the more rapid absorption of ethanol leading to higher Cmax and earlier tmax. The marked reduction in body weight after the operation might also be a factor to consider if the same absolute quantity of ethanol is consumed.
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20.
  • Koeck, Barbara, et al. (författare)
  • Angling selects against active and stress-resilient phenotypes in rainbow trout
  • 2019
  • Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - : Canadian Science Publishing. - 0706-652X .- 1205-7533. ; 76:2, s. 320-333
  • Tidskriftsartikel (refereegranskat)abstract
    • Selection induced by human harvest can lead to different patterns of phenotypic change than selection induced by natural predation and could be a major driving force of evolution of wild populations. The vulnerability of individuals to angling depends on the individual decision to ingest the bait, possibly mediated by their neuroendocrine response towards the associated stimulus. To investigate the mechanisms behind individual vulnerability to angling, we conducted angling experiments in replicated ponds and quantified individual behavioral traits and neuroendocrine stress responsiveness in two salmonid species, rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta). We discovered a phenotypic syndrome in rainbow trout, but not in brown trout, where lower serotonergic and dopaminergic brain activity and cortisol levels (i.e., lower stress responsiveness) in response to a standardized experimental stressor were associated with higher activity, forming a proactive phenotype that showed increased vulnerability to angling. Our results show that angling targets the most stress-resilient and active phenotypes of rainbow trout, supporting the suggestion that fishing-induced phenotypic selection may lead to an increased representation of stress-responsive and low-activity phenotypes in harvested populations.
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21.
  • Landeira-Dabarca, A., et al. (författare)
  • Cue recognition and behavioural responses in the three-spined stickleback (Gasterosteus aculeatus) under risk of fish predation
  • 2019
  • Ingår i: Acta Ethologica. - : Springer Science and Business Media LLC. - 0873-9749 .- 1437-9546. ; 22:3, s. 209-221
  • Tidskriftsartikel (refereegranskat)abstract
    • To effectively respond to predation risk, prey must assess the risk associated with different predation cues. Predation cues can stem either from the predator or from conspecifics and indicate different predation risk levels, thus eliciting different anti-predation responses. The three-spined stickleback is a well-studied fish species often found in gregarious formations. Previous studies show that sticklebacks perform a variety of anti-predation behaviours; however, little is known about how they respond to multiple simultaneous predator cues, characteristic of heterogeneous natural habitats. Here, we experimentally compare the relative importance of three types of predation cues (visual predator cue, chemical predator odour cue and chemical alarm cue from injured conspecifics) and their interactions, on anti-predation and foraging behaviour of sticklebacks. Results showed that (1) individual sticklebacks responded most strongly to visual predator cues, which resulted in reduced foraging activity, increased spine erection and increased predator inspection; (2) the presence of chemical cues (predator odour and/or conspecific alarm cues) stimulates freezing behaviour to a minor extent; and (3) anti-predation behaviour manifests as a trade-off with foraging-related activities. Overall, the results indicate that sticklebacks could assess risk and modify their behavioural responses depending on which cues are present in the environment. The experimental approach of using factorial combinations of different predatory cues can increase our understanding of the role of multimodal cues in aquatic ecosystems.
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22.
  • Larsen, M. H., et al. (författare)
  • Reduced rearing density increases postrelease migration success of Atlantic salmon (Salmo salar) smolts
  • 2016
  • Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - : Canadian Science Publishing. - 0706-652X .- 1205-7533. ; 73:5, s. 804-810
  • Tidskriftsartikel (refereegranskat)abstract
    • The overall aim of this study was to investigate the effect of rearing density on the postrelease survival of Atlantic salmon (Salmo salar) smolts during seaward migration. Fish were either reared at conventional hatchery density or at one-third of conventional density. Three hundred 1-year-old smolts from each density treatment were individually tagged with passive integrated transponder tags and released 3.2 km upstream of a stationary antenna array in a natural stream. There were no significant differences in length, body mass, or condition between fish from the two density treatments during rearing in the hatchery. However, individuals reared at reduced density had less eroded dorsal fins and opercula relative to those from the high-density treatment. In the stream, the downstream migration success was 16% higher for fish reared at reduced density than for conspecifics kept at high density, but the timing of migration was similar for both groups. These novel results suggest that conventionally high rearing densities may reduce welfare and the postrelease migration success of hatchery-reared Atlantic salmon.
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23.
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24.
  • Larsson, Ingrid, 1963, et al. (författare)
  • Body composition in the SOS (Swedish Obese Subjects) reference study
  • 2004
  • Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 0307-0565 .- 1476-5497. ; 28, s. 1317-1324
  • Tidskriftsartikel (refereegranskat)abstract
    • Department of Body Composition and Metabolism, Sahlgrenska Academy at Göteborg University, SE 41345 Göteborg, Sweden. lars.sjostrom@medfak.gu.se OBJECTIVE: The primary objective was to establish population-based, sex- and age-specific reference data with respect to body composition variables. Secondary objectives were to relate body mass index (BMI) to anthropometric measurements reflecting central adiposity and to body fat (BF). Another objective was to examine if secular changes in adipose tissue distribution occurred during the sampling period, 1994-1999. DESIGN: Sex- and age-specific data on anthropometric measurements and body composition were cross-sectionally collected in the reference study of Swedish Obese Subjects. SUBJECTS: In total, 1135 randomly selected subjects (524 men and 611 women), aged 37-61 y, BMI 17.6-45.4 kg/m(2). MEASUREMENTS: Measures of body fatness and fat distribution (by dual energy X-ray absorptiometry and anthropometry) were collected. RESULTS: At BMI 25 kg/m(2), relative (absolute) BF mass was 24% (19 kg) in men vs 36% (25 kg) in women, waist circumference was 90 vs 85 cm, and sagittal trunk diameter was 21 vs 19 cm. BF and measures of centralized adipose tissue distribution increased with age in both sexes (P<0.01). In women, waist circumference and sagittal diameter increased (P<0.01) over the sampling period while BMI did not. CONCLUSIONS: Sex- and age-specific reference data on body composition are reported from a randomly selected sample of Swedish men and women. At given BMIs, women had more BF but smaller waist circumference than men. Secular increases in indices of central obesity were found in women but not in men. PMID: 15314632 [PubMed - indexed for MEDLINE]
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25.
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26.
  • Liakopoulos, Vasileios, et al. (författare)
  • Changes in risk factors and their contribution to reduction of mortality risk following gastric bypass surgery among obese individuals with type 2 diabetes: A nationwide, matched, observational cohort study
  • 2017
  • Ingår i: BMJ Open Diabetes Research and Care. - : BMJ. - 2052-4897. ; 5:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective We recently showed that Roux-en-Y gastric bypass (RYGB) reduces risks of mortality, cardiovascular death and myocardial infarction in obese individuals compared with matched patients with diabetes mellitus (DM). We have examined changes in risk factors after RYGB, with the aim of explaining these effects. Research design and methods We matched (1:1) 6132 RYGB patients with DM reported to the Scandinavian Obesity Surgery Register with patients who had not undergone RYGB, based on sex, age, body mass index (BMI) and time, and assessed effects 2007-2014. We used causal mediation analysis to study effects mediated through changes to BMI and risk factors at 1 year based on Cox proportional hazards models. Results Baseline BMI was 42 kg/m2. Following RYGB, the lowest BMI was observed after 2 years (mean 31.9 kg/m2), and hemoglobin A1c (HbA1c) after 1 year (mean 6.32% (45.6 mmol/mol)). Maximum high-density lipoprotein (HDL) cholesterol was observed after 3-5 years (mean 1.46 mmol/L). Differences in BMI, HbA1c and HDL between the groups were statistically significant up to 6 years, and 2-3 years for low-density lipoprotein (LDL) and blood pressure, despite fewer glucose-lowering, hypertensive and lipid-lowering treatments. The causal mediation analysis suggested that RYGB has a positive effect on mortality risk, mainly by means of weight reduction (as opposed to changes to the risk factors analyzed). Conclusions Improvements in risk factors might contribute to the reduction of mortality risk after RYGB in obese individuals with type 2 diabetes, but the main effect seems to be mediated through a decrease in BMI, which could serve as a proxy for several mechanisms. © 2017, BMJ Publishing Group. All rights reserved.
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27.
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28.
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29.
  • Lundeberg, T, et al. (författare)
  • Acupuncture--self-appraisal and the reward system
  • 2007
  • Ingår i: Acupuncture in medicine : journal of the British Medical Acupuncture Society. - : SAGE Publications. - 0964-5284. ; 25:3, s. 87-99
  • Tidskriftsartikel (refereegranskat)abstract
    • Acupuncture is an ancient therapy with a variety of different explanatory models. A cascade of physiological effects has been reported, both in the peripheral and the central nervous system, following the insertion of a needle or light tapping of the skin. Clinical trials testing the specific claims of acupuncture have generally tried to focus on testing the efficacy of applying specific techniques and/or specified points. However, different conditions may respond differently to different modes of stimulation. Recently, it was demonstrated that both superficial and deep needling (with de qi/Hibiki) resulted in amelioration of patellofemoral pain and unpleasantness. The pleasurable aspect of the acupuncture experience has largely been ignored as it has been considered secondary to its pain alleviating effects. This aspect of acupuncture treatment is likely to be related to activation of self-appraisal and the reward system. When a patient seeks a therapist there are expectations of a specific effect. These expectations are partly based on self-relevant phenomena and self-referentia introspection and constitute the preference. Also, when asked about the effect of the treatment, processes that orientate pre-attentive anticipatory or mnemonic information and processes that mediate self-reflection and recollection are integrated together with sensory detection to enable a decision about the patient's perception of the effect of acupuncture treatment. These ‘self-appraisal’ processes are dependent on two integrated networks: a ventral medial prefrontal cortex paralimbic limbic ‘affective’ pathway and a dorsal medial prefrontal cortex cortical hippocampal ‘cognitive’ pathway. The limbic structures are implicated in the reward system and play a key role in most diseases and illness responses including chronic pain and depression, regulating mood and neuromodulatory responses (eg sensory, autonomic, and endocrine). The pleasurable and neuromodulatory aspects of acupuncture as well as ‘placebo needling’ may partly be explained by the activation or deactivation of limbic structures including the hippocampus, amygdala, and their connections with the hypothalamus. In patients with patellofemoral pain, the effects of superficial and deep needling remained for six months. These long term pain-alleviating effects have been attributed to activation of pain inhibiting systems in cortical and subcortical pathways. When considering long term effects the cortical cerebellar system needs to be taken into account. The cortical cerebellar system is probably central to the development of neural models that learn and eventually stimulate routinely executed (eg motor skills) and long term (eg pain alleviation) cognitive processes. These higher order cognitive processes are initially mediated in prefrontal cortical loci but later shift control iteratively to internal cerebellar representations of these processes. Possibly part of the long term healing effects of acupuncture may be attributed to changes in the cerebellar system thereby sparing processing load in cortical and subcortical areas. As cortical and subcortical structures are activated and/or de-activated following stimulation of receptors in the skin, disregarding site, ‘placebo or sham needling’ does not exist and conclusions drawn on the basis that it is an inert control are invalid. ‘Self’ may be seen as a shifting illusion, ceaselessly constructed and deconstructed, and the effect of acupuncture may reflect its status (as well as that of the therapist).
  •  
30.
  • Näslund, Joacim, 1985, et al. (författare)
  • Autumn food restriction reduces smoltification rate, but not over-winter survival, in juvenile brown trout Salmo trutta
  • 2017
  • Ingår i: Ecology of Freshwater Fish. - : Wiley. - 0906-6691 .- 1600-0633. ; 26:2, s. 205-216
  • Tidskriftsartikel (refereegranskat)abstract
    • The winter is often considered as a survival bottleneck for stream-living fish. Juvenile salmonids generally become less active during this period, and while food intake continues to some extent, growth rates are typically low. Here we present the results of an over-winter field experiment where energy levels were manipulated in late autumn. Three groups of juvenile (age 1+) brown trout, from an anadromous population, were monitored with respect to over-winter growth rate and survival (as indicated by recapture rates). Two groups were fed either high (HR), or low (LR) food rations in the laboratory for a month (October); the third group remained in the stream (STR). Over-winter growth rates were relatively low in all groups, and no growth compensation could be detected. Compared to HR and LR, STR fish had higher recapture rates after winter, indicating that laboratory housing may have affected the subsequent stream survival negatively. Comparing the two laboratory-housed groups, the LR group reached similar condition as the HR group in early spring, without indications of differences in survival. However, the initiation rate of body silvering (indicating initiation of smoltification) was lower in the LR group. Thus, it appears that food restriction during late autumn affect the onset of smoltification in juvenile brown trout. The results support previous laboratory studies indicating that salmonids modify their over-winter foraging behaviour to avoid too low energy levels at the end of winter. This modification appears to delay smoltification, but may not necessarily be costly in terms of over-winter mortality.
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31.
  • Näslund, Joacim, 1985, et al. (författare)
  • Behavioural reactions of three-spined sticklebacks to simulated risk of predation – effects of predator distance and movement
  • 2016
  • Ingår i: FACETS. - : Canadian Science Publishing. - 2371-1671. ; 1, s. 55-66
  • Tidskriftsartikel (refereegranskat)abstract
    • The behavioural response of animals to predation risk commonly depends on the behaviour of potential predators. Here, we report an experiment investigating effects of predator model (a life-like wooden trout model) distance and movement on the behaviour of three-spined sticklebacks Gasterosteus aculeatus L. in a standardized experimental setting. When the predator model was immobile, the behaviour of the sticklebacks could, in general, not be clearly distinguished from a no-predator control treatment. When moving the predator 41 cm towards the stickleback, clear anti-predator behaviours were observed. However, behavioural expression depended on the distance to the predator. At the two farthest distances (approaching from 129 to 88 cm and from 170 to 129 cm), the sticklebacks approached the predator and spent little time freezing. At the two closest distances (approaching from 88 to 47 cm and from 47 to 6 cm), the sticklebacks increased the distance to the predator model and froze their movements. These results suggest that the closest-distance groups showed avoidance behaviour, whereas the farthest-distance groups instead appeared to start inspecting the potential predator. This provides evidence for conditional anti-predator behaviour and highlights the importance of considering distance to, and movement of predator models when interpreting data from standardized behavioural trials.
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32.
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33.
  • Näslund, Joacim, 1985, et al. (författare)
  • Design of Emergence Test Arenas Can Affect the Results of Boldness Assays
  • 2015
  • Ingår i: Ethology. - : Wiley. - 0179-1613. ; 121:6, s. 556-565
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, we investigate whether and how arena design of emergence tests (a commonly used boldness assay where the latency to emerge from a start box is measured) can affect the behaviour of the subject animals. We used two populations of wild brown trout fry, captured on their hatching grounds, and measured emergence latency in arenas with two different sizes of start-box gates and two different environments into which the fish emerges from the start box (barren and complex), in a factorial design. We found that arena design affected the behaviour of the fish, but only in one of the populations. In the affected population, a large start-box gate in combination with a barren environment reduced emergence latency. Furthermore, the time from leaving the box until entering another compartment on the opposite side of the arena was shorter in a barren environment as compared to a more complex environment. We also found that smaller brown trout fry generally showed lower tendency for emerging from the start box at all. The results of this study suggest that direct comparisons among results from experiments using different arena designs may be problematic and highlight the importance of reporting details of arena design in publications. BOTT JC, 1989, BEHAVIOUR, V108, P104
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34.
  • Näslund, Joacim, 1985, et al. (författare)
  • Early enrichment effects on brain development in hatchery-reared Atlantic salmon (Salmo salar): no evidence for a critical period
  • 2012
  • Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - : Canadian Science Publishing. - 0706-652X .- 1205-7533. ; 69:9, s. 1481-1490
  • Tidskriftsartikel (refereegranskat)abstract
    • In hatcheries, fish are normally reared in barren environments, which have been reported to affect their phenotypic development compared with wild conspecifics. In this study, Atlantic salmon (Salmo salar) alevins were reared in conventional barren hatchery trays or in either of two types of structurally enriched trays. We show that increased structural complexity during early rearing increased brain size in all investigated brain substructures. However, these effects disappeared over time after transfer to barren tanks for external feeding. Parallel to the hatchery study, a group of salmon parr was released into nature and recaptured at smoltification. These stream-reared smolts developed smaller brains than the hatchery reared smolts, irrespective of initial enrichment treatment. These novel findings do not support the hypothesis that there is a critical early period determining the brain growth trajectory. In contrast, our results indicate that brain growth is plastic in relation to environment. In addition, we show allometric growth in brain substructures over juvenile development, which suggests that comparisons between groups of different body size should be made with caution. These results can aid the development of ecologically sound rearing methods for conservational fish-stocking programs.
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35.
  • Näslund, Joacim, 1985, et al. (författare)
  • Effects of early rearing environment on brain devlopment in Atlantic salmon
  • 2011
  • Ingår i: Oikos meeting 2011.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • The brain size of animals has previously been shown to be affected by environmental complexity. In an experiment we show that hatchery environment experienced early in life can affect the brain size in salmonid fish. Atlantic salmon were subjected to three different structural treatments during the alvelin stage: (1) stones scattered on the botton, (2) an artificial substrate grid, or (3) conventional barren hatchery trays. Our results show that stone treatment produce fish with larger brains than fish reared in barren trays, with grid treatment being intermediary. These effects were gradually reduced when the fish were moved to a standard barren hatchery environment. In addition, fish released into nature a half year prior to smoltification showed a higher degree of brain growth than age-matched-fish kept in the hatchery. The results show that brain growth in alvelins and parr is plastic and that enrichment affects brain development and thereby potentially fitness and behaviour.
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36.
  • Näslund, Joacim, 1985, et al. (författare)
  • Environment-dependent plasticity and ontogenetic changes in the brain of hatchery-reared Atlantic salmon
  • 2017
  • Ingår i: Journal of Zoology. - : Wiley. - 0952-8369 .- 1469-7998. ; 301:1, s. 75-82
  • Tidskriftsartikel (refereegranskat)abstract
    • Lowered rearing density has repeatedly been shown to increase the performance of hatchery-reared salmonids stocked into natural environments. One possible mechanism for this pattern could be that lower densities enhance brain development, which has been shown to be the case in other hatchery enhancement strategies, like environmental enrichment. Here, we investigated the size of the brain in hatchery-reared Atlantic salmon Salmo salar kept at standard (high) and reduced (low) tank densities. In contrast to our predictions, we found that fish reared at high density had larger dry mass of cerebellum and telencephalon, correcting for body size. No differences were detected for total brain mass. Furthermore, we found that the relative size of both telencephalon and cerebellum, in relation to total brain mass, changed with body size. Cerebellum increased in relative size with increased body size, while the opposite pattern was observed for telencephalon. Overall, these results reveal substantial brain plasticity depending on the surrounding environment as well as ontogenetic adaptive changes in the brain of the Atlantic salmon.
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37.
  • Näslund, Joacim, 1985, et al. (författare)
  • Environmental enrichment for fish in captive environments: effects of physical structures and substrates
  • 2016
  • Ingår i: Fish and Fisheries. - : Wiley. - 1467-2960 .- 1467-2979. ; 17:1, s. 1-30
  • Tidskriftsartikel (refereegranskat)abstract
    • Structural environmental enrichment, that is, a deliberate addition of physical complexity to the rearing environment, is sometimes utilized to reduce the expression of the undesirable traits that fish develop in captivity. Increasing demands and regulations regarding usage of enrichment to promote fish welfare also make investigations on the effects of enrichment important. Here, we sythesize the current state-of-the-art knowledge about the effects of structural environmental enrichment for fish in captive environments. We find that enrichment can affect several aspects of the biology of captive fish, for example, aggression, stress, energy expenditure, injury and disease susceptibility. Importantly, these effects are often varying in direction and magnitude, and it is clear that just addition of structure is not a solution to all problems in fish rearing. Each species and life stage needs special consideration with respect to its natural history and preferences. A multitude of different enrichment types has been investigated and many studies investigate several enrichment components at the same time, making comparisons among studies difficult. To the present date, the majority of efforts have been directed to investigate salmonid fish in stock-fish hatcheries and cichlids from a basic research perspective. Some contexts are under-studied with respect to environmental enrichment, for instance effects on results in basic research and welfare effects in display aquaria. There are many research opportunities left within this field. However, future studies could utilize experimental designs which make it possible to discriminate between effects of different environmental manipulations to a higher degree than what has been performed to this date.
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38.
  • Näslund, Joacim, 1985, et al. (författare)
  • Fish density, but not environmental enrichment, affects the size of cerebellum in the brain of juvenile hatchery-reared Atlantic salmon
  • 2019
  • Ingår i: Environmental Biology of Fishes. - : Springer Science and Business Media LLC. - 0378-1909 .- 1573-5133. ; 102, s. 705-712
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper describes a study on the environmentally dependent brain size plasticity in hatchery-reared Atlantic salmon Salmo salar L. Using a factorial experimental design, we tested whether tank fish density, local hatchery standard (150 fish ∙ m −2 ) vs. reduced (50 fish ∙ m −2 ) and structural enrichment, a bundle of submerged plastic stripes, had effects on the size of the cerebellar region of the brain. Fish reared at reduced density had smaller cerebella, while structural enrichment had no detectable effects. The density effect on cerebellum, which is involved in locomotion and cognition, confirms previous results from hatchery-reared Atlantic salmon. The lack of detectable positive effects of enrichment, which contrasts some previous studies, provide further evidence for a complex relationship between environmental complexity and brain growth.
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39.
  • Näslund, Joacim, 1985, et al. (författare)
  • Is behaviour in a novel environment associated with bodily state in brown trout Salmo trutta fry?
  • 2017
  • Ingår i: Ecology of Freshwater Fish. - : Wiley. - 0906-6691. ; 26:3, s. 462-474
  • Tidskriftsartikel (refereegranskat)abstract
    • Energetic status and body size are inconstant bodily states often considered to have feedback effects on behaviour. Feedbacks can be negative, like starvation-threshold feedbacks (lower state values=increased risk taking due to higher energy need, and vice versa), or positive, like state-dependent safety feedbacks (higher state values=lower vulnerability when expressing risky behaviours, and vice versa). Few studies have investigated feedback effects during the early-life survival bottleneck of territorial species, when rapid growth is particularly important to maintain competitive ability. We investigated effects of body size and energetic status on the emergence latency into an unknown environment in highly territorial brown trout fry. We manipulated energetic status using high and low food rations in different combinations over two consecutive periods. In contrast to results from other small-sized fishes, no general behavioural effects of energetic state were detected, but larger fish had on average shorter emergence latency. Starvation-threshold feedbacks were not supported, but the size effect favours the presence of a state-dependent safety feedback. When individuals were split into clusters characterised by long (>34s) and short (<34s) emergence latency, a state-dependent safety feedback, based on energetic status, was found in the short-latency cluster. Positive state-dependent feedbacks may reflect the high level of competition among wild trout fry during the first summer, particularly among the more active individuals (i.e., from the short latency cluster). High state levels could be utilised to gain advantages over lesser competitors (e.g., to establish territories), particularly if the overall risk of starvation is higher than the risk of predation.
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40.
  • Näslund, Joacim, 1985, et al. (författare)
  • Performance of wild brown trout in relation to energetic state and lab-scored activity during the early-life survival bottleneck
  • 2017
  • Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 71:11
  • Tidskriftsartikel (refereegranskat)abstract
    • The early life stage is typically a selective bottleneck during which individual performance is important for survival. We investigated size, energetic state, and activity, in relation to recapture probability in the youngest free-swimming stage of a territorial fish, the brown trout. In two experiments, we induced compensatory growth in wild-caught brown trout fry, using a restriction-refeeding protocol. Upon refeeding in the laboratory, the restricted trout showed compensatory growth in mass, but not in length. During this compensatory growth phase, we released the fish into their native stream habitat and then recaptured them after 1 month to assess survival and growth. Despite not having fully compensated body size at release, restricted fish did not show continued growth compensation in the stream, indicating that the natural environment limits growth capacity during early life. Individual baseline activity was scored in open-field tests before and after food restriction and was found repeatable but not significantly affected by growth manipulations. Under natural conditions, we found a positive association between open-field activity and survival (as indicated by recapture probability), but no significant differences between food-restricted and control fish. Initial body length positively influenced survival in the first experiment (early summer), but not in the second (late summer). These results contrast with the assumption that high baseline activity should be riskier in natural environments. For territorial animals, we hypothesize that activity is associated with high aggression and territoriality, which facilitates access to high-quality territories providing both shelter from predation and reduced starvation risk, which reduces mortality risk. In the early critical life stage, more active brown trout are better survivors. This finding, which contradicts general assumptions about the balance between predator exposure and food intake, could possibly be due to trout being highly territorial species in which active individuals can claim the best territories. We also find that young trout are likely limited in growth rate by environmental conditions in the wild, as growth compensation following food restriction is possible in the lab, but not realized in natural streams.
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41.
  • Näslund, Joacim, 1985, et al. (författare)
  • State-dependent behavior and alternative behavioral strategies in brown trout (Salmo trutta L.) fry
  • 2016
  • Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 0340-5443 .- 1432-0762. ; 70:12, s. 2111-2125
  • Tidskriftsartikel (refereegranskat)abstract
    • © 2016, The Author(s).Abstract: Animals generally adjust their behavior in response to bodily state (e.g., size and energy reserves) to optimize energy intake in relation to mortality risk, weighing predation probability against the risk of starvation. Here, we investigated whether brown trout Salmo trutta adjust their behavior in relation to energetic status and body size during a major early-life selection bottleneck, when fast growth is important. Over two consecutive time periods (P1 and P2; 12 and 23days, respectively), food availability was manipulated, using four different combinations of high (H) and low (L) rations (i.e., HH, HL, LH, and LL; first and second letter denoting ration during P1 and P2, respectively). Social effects were excluded through individual isolation. Following the treatment periods, fish in the HL treatment were on average 15–21% more active than the other groups in a forced open-field test, but large within-treatment variation provided only weak statistical support for this effect. Furthermore, fish on L-ration during P2 tended to be more actively aggressive towards their mirror image than fish on H-ration. Body size was related to behavioral expression, with larger fish being more active and aggressive. Swimming activity and active aggression were positively correlated, forming a behavioral syndrome in the studied population. Based on these behavioral traits, we could also distinguish two behavioral clusters: one consisting of more active and aggressive individuals and the other consisting of less active and aggressive individuals. This indicates that brown trout fry adopt distinct behavioral strategies early in life. Significance statement: This paper provides information on the state-dependence of behavior in animals, in particular young brown trout. On the one hand, our data suggest a weak energetic state feedback where activity and aggression is increased as a response to short term food restriction. This suggests a limited scope for behavioral alterations in the face of starvation. On the other hand, body size is linked to higher activity and aggression, likely as a positive feedback between size and dominance. The experiment was carried out during the main population survival bottleneck, and the results indicate that growth is important during this stage, as 1) behavioral compensation to increase growth is limited, and 2) growth likely increases the competitive ability. However, our data also suggests that the population separates into two clusters, based on combined scores of activity and aggression (which are positively linked within individuals). Thus, apart from an active and aggressive strategy, there seems to be another more passive behavioral strategy.
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42.
  • Näslund, Joacim, 1985, et al. (författare)
  • Telomere dynamics in wild brown trout: effects of compensatory growth and early growth investment
  • 2015
  • Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 177:4, s. 1221-1230
  • Tidskriftsartikel (refereegranskat)abstract
    • After a period of food deprivation, animals often respond with a period of faster than normal growth. Such responses have been suggested to result in decreased chromosomal maintenance, which in turn may affect the future fitness of an individual. Here, we present a field experiment in which a food deprivation period of 24 days was enforced on fish from a natural population of juvenile brown trout (Salmo trutta) at the start of the high-growth season in spring. The growth of the food-deprived fish and a non-deprived control group was then monitored in the wild during 1 year. Fin tissue samples were taken at the start of the experiment and 1 year after food deprivation to monitor the telomere dynamics, using reduced telomere length as an indicator of maintenance cost. The food- deprived fish showed partial compensatory growth in both mass and length relative to the control group. However, we found no treatment effects on telomere dynamics, suggest- ing that growth-compensating brown trout juveniles are able to maintain their telomeres during their second year in the stream. However, body size at the start of the experi- ment, reflecting growth rate during their first year of life, was negatively correlated with change in telomere length over the following year. This result raises the possibility that rapid growth early in life induces delayed costs in cellular maintenance.
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43.
  • Näslund, Joacim, 1985, et al. (författare)
  • Who will become dominant? Investigating the roles of individual behaviour, body size, and environmental predictability in brown trout fry hierarchies
  • 2018
  • Ingår i: European Journal of Ecology. - : The University of Kansas. - 1339-8474. ; 3:2, s. 123-133
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents a study investigating performance of brown trout fry, with different behavioural characteristics, in environments differing in food predictability. Based on previous experimental findings, we hypothesised that more active individuals would be favoured by a predictable environment, as compared to an unpredictable environment, as a consequence of being more aggressive and likely to dominate the best feeding stations. This hypothesis was not supported, as more active individuals instead tended to perform better, in terms of growth and survival, in unpredictable environments. However, this effect may stem from initial size differences, as more active fish also tended to be larger. In predictable environments, no trends between activity (or size) and performance were detected. Dominant individuals could be identified based on lighter body colouration in 9 out of 10 rearing tanks, but dominance appeared not to be related to activity score. The results highlight a potential advantage of more active and/or larger fry in unpredictable environments, while performance in predictable environments is likely depending on other phenotypic characteristics. Our general experimental approach can be useful for further developments in the investigation of performance of different ethotypes of brown trout fry. © 2017 Joacim Näslund et al..
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44.
  • Näslund, Tanja I (författare)
  • Viral vectors, in innate and adaptive immunity
  • 2009
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Recombinant viral vectors and DNA vectors induce strong immune responses in animal models. However, in clinical trials, the generation of immune responses is less robust, suggesting that further optimization and a deeper understanding of nucleic acid-based vaccines are required. Improvements, such as combining the vaccine vectors in heterologous prime boost regimens and/or using vectors that do not induce strong immune responses against the vector itself may enhance immune responses against the antigen-of-interest. In Paper I, we performed head-to-head comparisons of adenovirus, ALVAC and Semliki Forest virus (SFV) vectors, in homologous and heterologous prime boost regimens. The recombinant viral vectors were evaluated for their potency to generate T cell responses and to protect against a tumor challenge. We show that the memory T cell response induced by the different immunization regimens were distinctly different and that protection against a tumor challenge was more dependent on the quality of the response than the magnitude. The potency of the nucleic acid-based vaccines depends on the activation of innate signaling pathways. In Paper II-IV, we investigated innate signaling pathways activated by different viral vectors and the role of these pathways for induction of T cell responses. The CD8alpha+ DCs play a major role in cross-priming of anti-viral T cells. This dendritic cell subtype phagocytoses apoptotic bodies, expresses high levels of toll-like receptor (TLR) 3 and has a unique ability to cross-present exogenously derived cell-associated material. In Paper II, we investigated the role of TLR3 expression in the CD8alpha+ DCs and its relevance for cross-priming of T cells. We show that dsRNA activates CD8alpha+ DCs to cross-prime T cells via TLR3. In addition to TLRs, the cytoplasmic RNA receptors RIG-I and MDA5, expressed by most cell types, are detectors of viral infection. It was initially suggested that both RIG-I and MDA5 recognize double-stranded RNA (dsRNA) intermediates generated in the cytoplasm during viral infection in the host cell. However, negative-sense RNA viruses do not generate detectable levels of dsRNA in infected cells, thus these viruses may be recognized via alternative non-self signatures. In Paper III, we show that RIG-I is a receptor for single-stranded RNA molecules bearing 5 -phophates, illustrating one of the differences between RIG-I and MDA5 virus recognition. The alphavirus replicon-based DNA (DREP) vectors induce superior immune responses in comparison to conventional DNA (convDNA) vectors in animal models. We hypothesized that DREP vectors induce potent innate signaling pathways that account for the immunogenic properties of these vectors. In Paper IV, we investigated T cell responses in mice deficient in innate signaling pathways, including TLR3, TLR9, MyD88, IRF3 and the interferon alpha/beta receptor (IFN-AR1), after SFV viral and DNA based vector immunization. We show that IFN-AR1 and IRF3, but not detectably the other molecules, influence the T cell response induced by these vectors.
  •  
45.
  • Rosengren, Malin, 1982, et al. (författare)
  • Born to be wild: effects of rearing density and environmental enrichment on stress, welfare, and smolt migration in hatchery-reared Atlantic salmon
  • 2017
  • Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - : Canadian Science Publishing. - 0706-652X .- 1205-7533. ; 74:3, s. 396-405
  • Tidskriftsartikel (refereegranskat)abstract
    • Hatchery-reared salmonids released into the wild generally have poor survivability compared with wild conspecifics. To assess potential hatchery rearing improvements, behavioral and physiological effects of reducing animal density and adding in-tank shelter were investigated. Atlantic salmon (Salmo salar) parr were placed in barren or shelter-enriched tanks at high or low density up until release as smolts. Lowered density rendered positive effects on growth and intestinal barrier function, and both lowered density and shelter decreased conspecific aggression, as inferred by fin damage. Furthermore, while the presence of shelter decreased stress hormone levels following human disturbance, it also decreased growth and smolt migration success, an effect particularly pronounced at high densities. Therefore, we suggest that this type of structural enrichment should be avoided for Atlantic salmon smolts held at high densities and conclude that a lowered animal density with or without shelter has the highest potential in producing a more resilient smolt for stocking.
  •  
46.
  • Sanger, G J, et al. (författare)
  • GSK962040 : a small molecule, selective motilin receptor agonist, effective as a stimulant of human and rabbit gastrointestinal motility
  • 2009
  • Ingår i: Neurogastroenterology and Motility. - : Wiley. - 1350-1925 .- 1365-2982. ; 21:6, s. 657-664, e30-31
  • Tidskriftsartikel (refereegranskat)abstract
    • There is an urgent clinical need for a safe, efficacious stimulant of gastric emptying; current therapies include erythromycin (an antibiotic with additional properties which preclude chronic use) and metoclopramide (a 5-hydroxytryptamine type 4 receptor agonist and an antagonist at brain D2 receptors, associated with movement disorders). To move away from the complex motilide structure of erythromycin, a small molecule motilin receptor agonist, GSK962040, was identified and characterized. The compound was evaluated using recombinant human receptors, rabbit and human isolated stomach preparations known to respond to motilin and in vivo, by measuring its ability to increase defecation in conscious rabbits. At the human motilin receptor, the pEC50 (the negative logarithm to base 10 of the EC50 value, the concentration of agonist that produces 50% of the maximal response) values for GSK962040 and erythromycin as agonists were, respectively, 7.9 and 7.3; GSK962040 had no significant activity at a range of other receptors (including ghrelin), ion channels and enzymes. In rabbit gastric antrum, GSK962040 300 nmol L−1–10 μmol L−1 caused a prolonged facilitation of the amplitude of cholinergically mediated contractions, to a maximum of 248 ± 47% at 3 μmol L−1. In human-isolated stomach, GSK962040 10 μmol L−1, erythromycin 10 μmol L−1 and [Nle13]-motilin 100 nmol L−1, each caused muscle contraction of similar amplitude. In conscious rabbits, intravenous doses of 5 mg kg−1 GSK962040 or 10 mg kg−1 erythromycin significantly increased faecal output over a 2-h period. Together, these data show that GSK962040, a non-motilide structure, selectively activates the motilin receptor. Simplification of the structural requirements to activate this receptor greatly facilitates the design of potentially new medicines for gastroparesis.
  •  
47.
  • Sjöström, Lars, et al. (författare)
  • Swedish obese subjects (SOS). Recruitment for an intervention study and a selected description of the obese state
  • 1992
  • Ingår i: International Journal of Obesity. ; 19, s. 465-479
  • Tidskriftsartikel (refereegranskat)abstract
    • Department of Medicine, Sahlgren's Hospital, University of Göteborg, Sweden. SOS (Swedish obese subjects) is an on-going intervention trial designed to determine whether the mortality and morbidity rates among obese individuals who lose weight by surgical means (gastric banding, vertical banded gastroplasty and gastric by-pass) differ from the rates associated with conventional treatment. For this purpose, the study is recruiting a sample of obese men and women who constitute a registry of potential subjects from which the participants are drawn. Eligibility criteria for participation in the registry were: age at application 37-57 years and BMI greater than or equal to 34 kg/m2 for men and greater than or equal to 38 kg/m2 for women. Before receiving a health examination, all patients complete extensive questionnaires on current and past health status, utilization of medical care and medications, socio-economic status, psychological profiles, dietary habits, physical activity, weight history, and familial disposition to obesity. Each surgical case is matched to its optimal control in the registry, to ensure that the two groups do not differ systematically with respect to any of 18 matching variables that may affect prognosis. The first 1006 subjects included in the registry have been studied with respect to morbidity and compared with on-going population studies of men and women in Göteborg, Sweden. The relative risks of prevalent disease and symptoms associated with obesity in 50-year-old males and females respectively were 4.3 and 4.7 (dyspnoea), 14.7 and 11.8 (angina), 6.3 (myocardial infarction, males only), 2.1 and 4.5 (hypertension), 5.2 and 6.6 (diabetes), 4.6 and 26.1 (claudication) and 1.7 and 1.8 (gall bladder disease). Correspondingly, obese males and females display elevations of systolic and diastolic blood pressure, fasting glucose, insulin, triglyceride, and uric acid levels. However, total cholesterol was not increased in obese males and was in fact significantly lower in obese compared with reference women. HDL-cholesterol was lower in obese than reference men (data were not available in reference women). The rate of taking sick pensions was over twice as high in SOS obese patients than in population controls. Finally, comparison of measurements with self-reported prevalence estimates revealed a considerable amount of previously undiagnosed hypertension and diabetes in the obese subjects. These data suggest that the excess health risks associated with obesity may not be fully appreciated. PMID: 1322873 [PubMed - indexed for MEDLINE]
  •  
48.
  • Sundström, L. Fredrik, 1972, et al. (författare)
  • Density-Dependent Compensatory Growth in Brown Trout (Salmo trutta) in Nature
  • 2013
  • Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 8:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Density-dependence is a major ecological mechanism that is known to limit individual growth. To examine if compensatory growth (unusually rapid growth following a period of imposed slow growth) in nature is density-dependent, one-year-old brown trout (Salmo trutta L.) were first starved in the laboratory, and then released back into their natural stream, either at natural or at experimentally increased population density. The experimental trout were captured three times over a one-year period. We found no differences in growth, within the first month after release (May-June), between the starved fish and the control group (i.e. no evidence of compensation). During the summer however (July-September), the starved fish grew more than the control group (i.e. compensation), and the starved fish released into the stream at a higher density, grew less than those released at a natural density, both in terms of weight and length (i.e. density-dependent compensation). Over the winter (October-April), there were no effects of either starvation or density on weight and length growth. After the winter, starved fish released at either density had caught up with control fish in body size, but recapture rates (proxy for survival) did not indicate any costs of compensation. Our results suggest that compensatory growth in nature can be density-dependent. Thus, this is the first study to demonstrate the presence of ecological restrictions on the compensatory growth response in free-ranging animals.
  •  
49.
  •  
50.
  • Tinoco, Ana B, et al. (författare)
  • Ghrelin increases food intake, swimming activity and growth in juvenile brown trout (Salmo trutta)
  • 2014
  • Ingår i: Physiology and Behavior. - : Elsevier BV. - 0031-9384 .- 1873-507X. ; 124, s. 15-22
  • Tidskriftsartikel (refereegranskat)abstract
    • Several key functions of ghrelin are well conserved through vertebrate phylogeny. However, some of ghrelin's effects are contradictory and among teleosts only a limited number of species have been used in functional studies on food intake and foraging-related behaviors. Here we investigated the long-term effects of ghrelin on food intake, growth, swimming activity and aggressive contest behavior in one year old wild brown trout (Salmo trutta) using intraperitoneal implants. Food intake and swimming activity were individually recorded starting from day 1, and aggressive behavior was tested at day 11, after ghrelin implantation. Body weight and growth rate were measured from the beginning to the end of the experiment. Triglycerides and lipase activity in muscle and liver; monoaminergic activity in the telencephalon and brainstem; and neuropeptide Y (NPY) mRNA levels in the hypothalamus were analyzed. Ghrelin treatment was found to increase food intake and growth without modifying lipid deposition or lipid metabolism in liver and muscle. Ghrelin treatment led to an increased foraging activity and a trend towards a higher swimming activity. Moreover, ghrelin-treated fish showed a tendency to initiate more conflicts, but this motivation was not reflected in a higher ability to win the conflicts. No changes were observed in monoaminergic activity and NPY mRNA levels in the brain. Ghrelin is therefore suggested to act as an orexigenic hormone regulating behavior in juvenile wild brown trout. These actions are accompanied with an increased growth without the alteration of liver and muscle lipid metabolism and they do not seem to be mediated by changes in brain monoaminergic activity or hypothalamic expression of NPY.
  •  
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