| 1. |
- Axelsson, K. F., et al.
(författare)
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Fracture Risk After Gastric Bypass Surgery : A Retrospective Cohort Study
- 2018
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Ingår i: Osteoporosis International. - : Springer London. - 0937-941X .- 1433-2965. ; 29:Suppl. 1, s. S491-S491
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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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| 2. |
- Johnsson, Jörgen I, 1959, et al.
(författare)
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Studying behavioural variation in salmonids from an ecological perspective: observations questions methodological considerations
- 2018
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Ingår i: Reviews in Fish Biology and Fisheries. - : Springer Science and Business Media LLC. - 0960-3166 .- 1573-5184. ; 28:4, s. 795-823
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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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| 3. |
- Koeck, Barbara, et al.
(författare)
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Angling selects against active and stress-resilient phenotypes in rainbow trout
- 2019
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Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - : Canadian Science Publishing. - 0706-652X .- 1205-7533. ; 76:2, s. 320-333
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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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| 4. |
- Landeira-Dabarca, A., et al.
(författare)
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Cue recognition and behavioural responses in the three-spined stickleback (Gasterosteus aculeatus) under risk of fish predation
- 2019
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Ingår i: Acta Ethologica. - : Springer Science and Business Media LLC. - 0873-9749 .- 1437-9546. ; 22:3, s. 209-221
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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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| 5. |
- Larsen, M. H., et al.
(författare)
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Reduced rearing density increases postrelease migration success of Atlantic salmon (Salmo salar) smolts
- 2016
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Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. - : Canadian Science Publishing. - 0706-652X .- 1205-7533. ; 73:5, s. 804-810
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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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| 6. |
- Liakopoulos, Vasileios, et al.
(författare)
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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
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Ingår i: BMJ Open Diabetes Research and Care. - : BMJ. - 2052-4897. ; 5:1
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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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| 7. |
- Näslund, Joacim, 1985, et al.
(författare)
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Autumn food restriction reduces smoltification rate, but not over-winter survival, in juvenile brown trout Salmo trutta
- 2017
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Ingår i: Ecology of Freshwater Fish. - : Wiley. - 0906-6691 .- 1600-0633. ; 26:2, s. 205-216
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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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| 8. |
- Näslund, Joacim, 1985, et al.
(författare)
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Behavioural reactions of three-spined sticklebacks to simulated risk of predation – effects of predator distance and movement
- 2016
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Ingår i: FACETS. - : Canadian Science Publishing. - 2371-1671. ; 1, s. 55-66
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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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| 9. |
- Näslund, Joacim, 1985, et al.
(författare)
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Design of Emergence Test Arenas Can Affect the Results of Boldness Assays
- 2015
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Ingår i: Ethology. - : Wiley. - 0179-1613. ; 121:6, s. 556-565
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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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| 10. |
- Näslund, Joacim, 1985, et al.
(författare)
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Environment-dependent plasticity and ontogenetic changes in the brain of hatchery-reared Atlantic salmon
- 2017
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Ingår i: Journal of Zoology. - : Wiley. - 0952-8369 .- 1469-7998. ; 301:1, s. 75-82
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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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