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  • 1.
    Amundin, Mats
    et al.
    Kolmården Wildlife Park.
    Hållsten, Henrik
    Filosofiska institutionen, Stockholms universitet.
    Eklund, Robert
    Linköpings universitet, Institutionen för kultur och kommunikation, Avdelningen för språk och kultur. Linköpings universitet, Filosofiska fakulteten.
    Karlgren, Jussi
    Kungliga Tekniska Högskolan.
    Molinder, Lars
    Carnegie Investment Bank, Swedden.
    A proposal to use distributional models to analyse dolphin vocalisation2017Inngår i: Proceedings of the 1st International Workshop on Vocal Interactivity in-and-between Humans, Animals and Robots, VIHAR 2017 / [ed] Angela Dassow, Ricard Marxer & Roger K. Moore, 2017, s. 31-32Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper gives a brief introduction to the starting points of an experimental project to study dolphin communicative behaviour using distributional semantics, with methods implemented for the large scale study of human language.

  • 2.
    du Preez, Marinus
    et al.
    North-West University, South Africa.
    Govender, Danny
    South African National Parks, South Africa.
    Kylin, Henrik
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Bouwman, Hindrik
    North-West University, South Africa.
    Metallic elements in Nile Crocodile eggs from the Kruger National Park, South Africa2018Inngår i: Ecotoxicology and Environmental Safety, ISSN 0147-6513, E-ISSN 1090-2414, Vol. 148, s. 930-941Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Nile Crocodile is the largest predator on the African continent. Recent mass mortalities in the Kruger National Park (KNP) raised concerns about possible influence of pollution. We analysed eggs and their eggshells collected from nests inside the KNP and from a crocodile farm for metallic elements. We found that mercury, selenium, and copper occurred at levels of concern. Eggshells had very high concentrations of iron. Apart from toxicological implications associated with elevated concentrations in eggs, we found iron possibly contributing towards thicker eggshells. Thicker shells may act as a barrier to gas and water exchange, as well as possibly increasing the effort required for the hatchling to emerge from tightly packed shells under sand. Pollutants are transported into the KNP via rivers, and possibly via air. Mercury and copper pollution are waste-, industrial- and mining-related; ecotoxicological concern should therefore be extended to all areas where the four African crocodile species occur. Reptiles are under-represented in ecotoxicological literature in general, and especially from Africa. We know of only one previous report on metals and metalloids in crocodile eggs from Africa (Zimbabwe), published 30 years ago. Reduced fitness, endocrine disruption and effects on behaviour are other possible sub-lethal effects associated with metallic elements that may only become apparent decades later in a long-lived species such as the Nile Crocodile. In the face of habitat destruction, pollution, human population increases, and climate change, further research is needed regarding pollutant concentrations and effects in all African reptiles . The rivers that carry water from outside the park sustain its aquatic life, but also transport pollutants into the KNP. Therefore, improved source mitigation remains an important task and responsibility for all involved.

  • 3.
    Foyer, Pernilla
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten. Department of Military Studies, Military-Technology Division, Swedish Defence University, Stockholm, Sweden.
    Svedberg, Anna-Maria
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Nilsson, Emma
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Wilsson, Erik
    Swedish Armed Forces Dog Training Unit, Märsta, Sweden.
    Olsen Faresjö, Åshild
    Linköpings universitet, Institutionen för medicin och hälsa, Avdelningen för samhällsmedicin. Linköpings universitet, Medicinska fakulteten.
    Jensen, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Behavior and cortisol responses of dogs evaluated in a standardized temperament test for military working dogs2016Inngår i: Journal of Veterinary Behavior: Clinical Applications and Research, ISSN 1558-7878, E-ISSN 1878-7517, Vol. 11, s. 7-12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Military and police working dogs are often exposed to stressful or threatening events, and an improper response, e.g., fear, may implicate both reduced working efficiency and welfare. Therefore, identifying individuals that display a favorable response to potentially threatening situations is of great interest. In the present study, we investigated behavior responses of 85 prospective military working dogs in 4 subtests in a standardized temperament test used to select working dogs for the Swedish Armed Forces. Our goal was to evaluate behavioral responses in specific subtests and cortisol responses of candidate dogs. After dogs were rated as approved or nonapproved based on the test leader’s assessment of the full test result, we independently analyzed video recordings of 4 subtests. In addition, for 37 dogs, we analyzed pretest and posttest salivary cortisol levels. Dogs which were approved by the test leader for further training scored higher in the video recordings on emotionality and, in particular, fear-related behavior during a subset of the test and had higher levels of cortisol both before and after the test, than nonapproved dogs. Although this may actually reflect the desired traits, it could also indicate a bias in the selection procedure, which may pose limitations on the attempts to recruit the most suitable working dogs.

  • 4.
    Girvan, Pilar
    Linköpings universitet, Institutionen för tema, Tema Genus.
    Clearing up the bullshit: Deconstructing 'feminisation', gender stereotypes and gender biases within UK veterinary surgery2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This thesis explores ‘feminisation’ discourse(s) within the UK veterinary profession, including the ways in which gender stereotypes and biases also influence such discourses and experiences of working within the field. Drawing upon and combining a range of sociological, organisational and feminist theories such as Witz’s (1992) theory of gendered professional projects and Butler’s (1990) highly influential notion of performativity, I am able to contextualise and expand upon the ‘doing’ of the veterinary profession as well as being able to frame ‘feminisation’ discourses as paradoxes, potentially producing the effects they articulate. My analysis is divided into two parts; the first deals with results of a 463 participant survey of veterinary workers regarding definitions, perceptions and observations of ‘feminisation’ and gender difference, highlighting the significance of this subject matter within their professional lives. The second part incorporates a deeper thematic analysis of particular everyday realities, emerging from four semi-structured interviews which also aimed to explore in greater detail individual perceptions and observations regarding ‘feminisation’ and gender biases and stereotypes, encouraging participants themselves to reflect upon their experiences. A number of conclusions emerged during the analysis, including an intriguing insight that those who tended to draw most strongly on gender stereotypes and biases to outline their perceptions and observations were paradoxically those who most vehemently believed gender was irrelevant. Fundamentally however this study concludes that the concept of ‘feminisation’ is a fluid conceptualisation, a cultural process and not just empirical category of ‘empty rhetoric’ as commonly utilised and applied to the veterinary profession; as such it has the potential to be utilised extensively to progress the profession in terms of wider inclusiveness, equality, transformation, in offering reconceptualised ways of considering what it means to be part of a ‘profession’ not predicated on patriarchal structures, and to ultimately reperceive how gender can be (re/un)enacted in transformative ways alongside progressively rearticulated ‘feminisation’ discourses.

  • 5.
    Gizejewski, Z
    et al.
    Institute of Animal Breeding and Food Research, Polish Academy of Sciences, Olsztyn, Poland.
    Söderquist, L
    Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Sciences, SLU, Uppsala, Sweden.
    Rodriguez-Martinez, Heriberto
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Utvecklingsbiologi. Linköpings universitet, Hälsouniversitetet.
    Genital and sperm characteristics of wild, free rangingred deer stags (Cervus elaphus L) hunted in different regions of Poland2010Inngår i: Wildlife Biology in Practice, ISSN 1646-1509, E-ISSN 1646-2742, Vol. 6, nr 2, s. 81-94Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In an attempt to establish reference values for sperm morphology in wild red deer, genital tracts were collected from thirty-six 3-11 years old free-ranging, wild red deer stags (Cervus elaphus L) shot down during 3 consecutive mating seasons (1996-1998) at three different environmental regions of Poland, defining two major ecotypes: (i) highland (outer eastern Carpathian range, Bieszczady mountains) and, (ii) lowland (Mazuria and Pomerania) and studied within 4.5h-49h after death for testis (T), epididymides (E) and vesicular gland (VG) variables. Spermatozoa collected from the E-cauda were examined for motility and morphology (light and electron microscopy levels). Both T size and weight and VS-weight differed with age (P<0.05-0.01) while habitat influenced T size and weight (P<0.01) a well as sperm motility (P<0.05). Neither sperm numbers nor morphology showed significant differences, mostly owing to

    the large variation recorded among stags (range 1-72%). Domain-grouped sperm morphological deviations were <5%, the mean total proportion of abnormal spermatozoa ranging 7.2-17.5%. Although variation was present, the values ought to be used as reference for spermiogrammes.

  • 6.
    Hultling, C
    et al.
    Department of Rehabilitation Medicine, Karolinska Institute, Stockholm, Sweden.
    Rosenlund, B
    Department of Rehabilitation Medicine, Karolinska Institute, Stockholm, Sweden.
    Levi, Richard
    Department of Rehabilitation Medicine, Karolinska Institute, Stockholm, Sweden.
    Fridström, M
    Department of Rehabilitation Medicine, Karolinska Institute, Stockholm, Sweden.
    Sjöblom, P
    Department of Rehabilitation Medicine, Karolinska Institute, Stockholm, Sweden.
    Hillensjö, T
    Department of Rehabilitation Medicine, Karolinska Institute, Stockholm, Sweden.
    Assisted ejaculation and in-vitro fertilization in the treatment of infertile spinal cord-injured men: the role of intracytoplasmic sperm injection.1997Inngår i: Human Reproduction, ISSN 0268-1161, E-ISSN 1460-2350, Vol. 12, nr 3, s. 499-502Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of the present longitudinal descriptive study was to extend previous observations on the benefit of in-vitro fertilization (IVF) in cases of anejaculatory infertility due to spinal cord injuries (SCI) and to report results achieved by intracytoplasmic sperm injection (ICSI). The study was performed in a national referral unit for SCI, Spinalis SCI Research Unit, the Karolinska Institute. The patient material consisted of couples with SCI men seeking treatment for their infertility. The inclusion criteria were: stable relationship, motile spermatozoa in a diagnostic sample and no female contraindications. Spermatozoa were retrieved through electroejaculation or vibratory stimulation. If the sperm quality was judged to be sufficient, standard IVF was performed. ICSI was employed if the semen quality was extremely poor. We have treated 25 couples in 52 cycles, leading to 81 ovum retrievals and 47 embryo transfers. Total sperm counts were very variable (0.01-978 x 10(6)). Before the introduction of ICSI the fertilization rate was 30%. ICSI increased the fertilization rate to 88%. There was no association between the pregnancy rate and the sperm count, level of injury or fertilization technique. A total of 16 clinical pregnancies was established, leading to 11 deliveries. This gives a cumulative pregnancy rate per couple of 56%.

  • 7.
    Lerner, Henrik
    Linköpings universitet, Institutionen för kultur och kommunikation, Centrum för tillämpad etik. Linköpings universitet, Filosofiska fakulteten.
    Transeminarium om eutanasi för människa och av djur2010Inngår i: Svensk Veterinärtidning, ISSN 0346-2250, Vol. 62, nr 10, s. 23-25Artikkel, forskningsoversikt (Annet vitenskapelig)
  • 8.
    Martinez, Cristina Alicia
    et al.
    University of Murcia, Murcia, Spain; Campus de Ciencias de la Salud, Murcia, Spain.
    Cambra, Josep Miquel
    University of Murcia, Murcia, Spain; Campus de Ciencias de la Salud, Murcia, Spain.
    Parrilla, Inmaculada
    University of Murcia, Murcia, Spain; Campus de Ciencias de la Salud, Murcia, Spain.
    Lucas, Xiomara
    University of Murcia, Murcia, Spain; Campus de Ciencias de la Salud, Murcia, Spain.
    Rodriguez-Martinez, Heriberto
    Linköpings universitet, Institutionen för klinisk och experimentell medicin. Linköpings universitet, Medicinska fakulteten.
    Martinez, Emilio Arsenio
    University of Murcia, Murcia, Spain; Campus de Ciencias de la Salud, Murcia, Spain.
    Izpisua, Juan Carlos
    Salk Institute for Biological Studies, La Jolla, CA, USA.
    Cuello, Cristina
    University of Murcia, Murcia, Spain; Campus de Ciencias de la Salud, Murcia, Spain.
    Gil, Maria Antonia
    University of Murcia, Murcia, Spain; Campus de Ciencias de la Salud, Murcia, Spain.
    Three-to-5-day weaning-to-estrus intervals do not affect neither efficiency of collection nor in vitro developmental ability of in vivo-derived pig zygotes2019Inngår i: Theriogenology, ISSN 0093-691X, E-ISSN 1879-3231, Vol. 141, s. 48-53Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient system to collect large numbers of vital zygotes is a pre-requisite for application of zygote genome-editing technology, including development of efficient models for xenotransplantation using pigs. Owing to the sub-optimal in vitro production of zygotes in pigs, efficient collection of in vivo developed zygotes is required. Timing of ovulation is a key factor to sustain efficiency since the interval between pronuclear formation and the first division is very short in pigs. The weaning-to-estrus interval can, due to its inverse relation with length of estrus and time of ovulation, interfere with ovulation and make it asynchronous, which reduces the probability of obtaining zygotes. This retrospective study compared the effects of three weaning-to-estrus intervals of 3, 4 or 5 days on zygote collection efficiency in a total of 17 trials over a 3-year period including 223 sows. Donor sows in groups of 10–15 animals were super-ovulated with eCG 24 h after weaning and those in estrus at 48–72 h post-eCG were immediately treated with hCG, followed by insemination 6 and 24 h thereafter. Collected structures during laparotomy on Day 2 (Day 0: onset of estrus) were morphologically evaluated and only those with a single cell and two visible polar bodies were considered as zygotes. Zygotes were injected with CRISPR-Cas9 editor mixture and cultured for 6 days to evaluate their developmental ability against non-injected control zygotes. Of all recovered structures (N = 5,468), 67.4%, 30.8% and 1.8% were zygotes, 2-cell embryos and oocytes-degenerated embryos, respectively. The different weaning-to-estrus intervals did not affect either the percentages of collected zygotes (range: 64.1%–70.0%) or the percentages of sows with zygotes at collection time (range: 69.0%–73.3%). The weaning-to-estrus intervals did not affect the in vitrodevelopmental ability of zygotes. After 24 h of culture, 78.1 ± 2.0% and 95.1 ± 0.6 (P < 0.05) of injected (N = 2,345) and non-injected (N = 335) zygotes, respectively, developed to 2-to-4-cell embryo stage. The total efficiency of the system was 64.1 ± 2.2% and 85.8 ± 1.5% (P < 0.05) for injected and non-injected zygotes, respectively. In conclusion, the results indicate that neither the efficiency of collecting in vivo derived porcine zygotes from superovulated sows nor the zygote ability to develop to blastocyst after cytoplasmic genome-editing injection were affected by a weaning-to-estrus interval between 3-to-5 days.

  • 9.
    Roca, J.
    et al.
    University of Murcia, Spain.
    Parrilla, I.
    University of Murcia, Spain.
    Gil, M. A.
    University of Murcia, Spain.
    Cuello, C.
    University of Murcia, Spain.
    Martinez, E. A.
    University of Murcia, Spain.
    Rodriguez-Martinez, Heriberto
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Avdelningen för kliniska vetenskaper. Linköpings universitet, Medicinska fakulteten.
    Non-viable sperm in the ejaculate: Lethal escorts for Contemporary viable sperm2016Inngår i: Animal Reproduction Science, ISSN 0378-4320, E-ISSN 1873-2232, Vol. 169, s. 24-31Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Non-viable sperm ("dead sperm") are present invariable numbers in mammalian ejaculates and their number increase substantially when semen is stored, particularly cryopreserved. This review comparatively highlights, with experimental data in porcine, the role-played by non-viable sperm in the outcome of semen used in assisted reproductive technologies. As well, the review discusses our current understanding of their origin and the pathways involved when their large numbers negative influence the functional lifespan of contemporary viable sperm to eventually cause irreversible dysfunction that reduces their fertility potential and their ability to develop healthy embryos. Finally, it highlights procedures currently available to mitigate these harmful effects. (C) 2016 Elsevier B.V. All rights reserved.

  • 10.
    Sellman, Stefan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Quantifying Risk in Epidemiological and Ecological Contexts2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The rates of globalization and growth of the human population puts ever increasing pressure on the agricultural sector to intensify and grow more complex, and with this intensification comes an increased risk of outbreaks of infectious livestock diseases. At the same time, and for the same reasons, the detrimental effect that humans have on other species with which we share the environment has never been more apparent, as the current rates of species loss from ecological communities rival those of ancient mass extinction events. In order to find ways to lessen the effects of and eventually solve such problems we need ways to quantify the risks involved, something that can be difficult when for instance the sheer size or sensitivity of the systems makes practical experimentation unsuitable. For these situations mathematical models have become invaluable tools due to their flexibility and noninvasiveness. This thesis presents four works involving the quantification of risk in livestock epidemic and ecological contexts using mathematical models. Two of them deal with extinctions of species within model ecological communities, and how species interactions play a role in the identity of the lost species following perturbations to specific species (Papers I and II). The other two regard how the spatial layout of the underlying population of livestock premises affect the risk of foot and mouth disease outbreaks among farms in the USA, and how models of such outbreaks can be optimized to improve their usefulness (Papers III and IV).

    Ecological communities consist of species and the often intricate pattern of interactions between them. These interspecies connections can propagate effects caused by disturbances in one end of the network, through the community via the links, to other parts of the network. In some cases, a reduction in the abundance of one species can cause the extinction of a second species before the first species disappears, something called functional extinction. Despite this, many conservation efforts revolve around simply keeping populations of single species at a high enough level for their own survival. In a model setting, the study of Paper I explores and attempts to quantify how common such functional extinctions are in relation to the alternative outcome that a perturbed species itself becomes extinct. This is done by first constructing stable model food webs describing predator-prey interactions of up to 50 species, parameterized through allometric relationships between metabolic processes and body size. Then the smallest amount of extra mortality that can be applied to each and every species in the web before any species become extinct is determined. The study shows that in these model communities, more often than not (>80%) another species, rather than the species that is subjected to the additional mortality will be the one to become extinct first.

    The approach of Paper I is taken further in Paper II by applying the same methodology to ecological networks that include mixtures of both antagonistic (predator-prey) and mutualistic (e.g. pollination and seed dispersal) interactions. The results further reinforce the findings of Paper I, and show that ecological networks containing a mixture of antagonistic and mutualistic interactions are more sensitive to functional extinctions than purely antagonistic or purely mutualistic ones, an important finding considering the diversity of interaction types in natural systems. Furthermore, the type of species found to have the lowest threshold before becoming functionally extinct were those with a mixture of interaction types, such as pollinating insects. Both Paper I and II consolidate the notion that when doing conservation work it is important to have the entire community in mind by considering the population sizes that are viable from a multi-species perspective, rather than just focusing on the minimum population sizes that are viable for the individual species.

    In Papers III and IV the focus changes somewhat, from models of ecological systems to models of how infectious livestock disease spread between farms in spatially explicit contexts. For this kind of model, information about the spatial distribution of the hosts is of course crucial, but not always readily available. In the USA, the only available information about livestock premises demography is aggregated at the county scale, meaning that the spatial distribution of the premises within each county is unknown. However, a method exists to simulate realistic stochastic spatial configurations of premises using a set of predictor variables, such as topology, climate and roads. An alternative approach that have been used previously is to assume a uniformly random spatial distribution of premises within each county. But to what extent does the choice between these two methods affect the model’s evaluation of the risk of disease outbreaks? In Paper III, this is analyzed specifically for foot and mouth disease. Through simulated outbreaks and by looking at the reproductive ratio of the disease, the outbreak dynamics within the two different spatial configurations of premises are compared. The results show that there is a clear difference in the risk of outbreaks between them, with the non-uniform distributions showing a general pattern of higher outbreak risk. However this difference is dependent on the size and geographic location of the county that the outbreak start in with larger counties in the west of the US showing a stronger effect.

    When running numerical simulations with large scale models such as the one used in Paper III, a considerable amount of replication is usually necessary in order to account for the high degree of stochasticity inherent to the problem. Even further replication is required when performing sensitivity analyses of model parameters or when exploring different scenarios, for instance when trying to determine the optimal control strategy for a disease. For this reason, the amount and quality of results that can be produced by such studies can quickly become limited by the availability of computational resources. Finding ways to optimize the computations involved with regard to simulation time is therefore of great value as it can be directly related to the robustness of the results. In Paper IV, an efficient optimization method for the kind of kernel-based local disease spread model used in paper III is presented. The method revolves around constructing a grid structure that is overlaid on top of the farm landscape and dividing the infection process into two steps, first evaluating if any farms within one of the grid squares can become infected given an over-estimation of the probability of infection, and then only if so, evaluate actual infection of a subset of the farms within the receiving square. The method is compared to similar published methods and is shown to be more efficient in most cases, while also being easy to implement and understand. Furthermore, while other methods often involve approximations of the transmission process in order to improve computational speed, the method of Paper IV is shown to be exact. This is a major advantage, since with an approximative method the extent to which the results are affected by the simplification is unknown unless the effect of the approximation is explicitly quantified. In most cases, such quantification would require extensive simulations with the unsimplified approach, something which of course may not be feasible.

    Delarbeid
    1. High frequency of functional extinctions in ecological networks
    Åpne denne publikasjonen i ny fane eller vindu >>High frequency of functional extinctions in ecological networks
    2013 (engelsk)Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 499, nr 7459, s. 468-+Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Intensified exploitation of natural populations and habitats has led to increased mortality rates and decreased abundances of many species(1,2). There is a growing concern that this might cause critical abundance thresholds of species to be crossed(1,3-5), with extinction cascades and state shifts in ecosystems as a consequence(4,6,7). When increased mortality rate and decreased abundance of a given species lead to extinction of other species, this species can be characterized as functionally extinct even though it still exists. Although such functional extinctions have been observed in some ecosystems(3,4,8), their frequency is largely unknown. Here we use a new modelling approach to explore the frequency and pattern of functional extinctions in ecological networks. Specifically, we analytically derive critical abundance thresholds of species by increasing their mortality rates until an extinction occurs in the network. Applying this approach on natural and theoretical food webs, we show that the species most likely to go extinct first is not the one whose mortality rate is increased but instead another species. Indeed, up to 80% of all first extinctions are of another species, suggesting that a species ecological functionality is often lost before its own existence is threatened. Furthermore, we find that large-bodied species at the top of the food chains can only be exposed to small increases in mortality rate and small decreases in abundance before going functionally extinct compared to small-bodied species lower in the food chains. These results illustrate the potential importance of functional extinctions in ecological networks and lend strong support to arguments advocating a more community-oriented approach in conservation biology, with target levels for populations based on ecological functionality rather than on mere persistence(8-11).

    sted, utgiver, år, opplag, sider
    Nature Publishing Group, 2013
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-96709 (URN)10.1038/nature12277 (DOI)000322157900038 ()
    Merknad

    Funding Agencies|Linkoping University||

    Tilgjengelig fra: 2013-08-23 Laget: 2013-08-23 Sist oppdatert: 2018-02-18
    2. Pattern of functional extinctions in ecological networks with a variety of interaction types
    Åpne denne publikasjonen i ny fane eller vindu >>Pattern of functional extinctions in ecological networks with a variety of interaction types
    2016 (engelsk)Inngår i: Theoretical Ecology, ISSN 1874-1738, E-ISSN 1874-1746, Vol. 9, nr 1, s. 83-94Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    There is a strong trend of declining populations in many species of both animals and plants. Dwindling numbers of species can eventually lead to their functional extinction. Functional, or ecological, extinction occurs when a species becomes too rare to fulfill its ecological, interactive role in the ecosystem, leading to true (numerical) extinction of other depending species. Recent theoretical work on food webs suggests that the frequency of functional extinction might be surprisingly high. However, little is known about the risk of functional species extinctions in networks with other types of interactions than trophic ones. Here, we explore the frequency of functional extinctions in model ecological networks having different proportions of antagonistic and mutualistic links. Furthermore, we investigate the topological relationship between functionally and numerically extinct species. We find that (1) the frequency of functional extinctions is higher in networks containing a mixture of antagonistic and mutualistic interactions than in networks with only one type of interaction, (2) increased mortality rate of species having both mutualistic and antagonistic links is more likely to lead to extinction of another species than to extinction of the species itself compared to species having only mutualistic or antagonistic links, and (3) trophic distance (shortest path) between functionally and numerically extinct species is, on average, longer than one, indicating the importance of indirect effects. These results generalize the findings of an earlier study on food webs, demonstrating the potential importance of functional extinction in a variety of ecological network types.

    sted, utgiver, år, opplag, sider
    Springer Netherlands, 2016
    Emneord
    Functional extinction, Declining populations, Interaction type, Interaction strength, Ecological network
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-121570 (URN)10.1007/s12080-015-0275-7 (DOI)000373308600009 ()
    Merknad

    Funding agencies: Linkoping University

    Tilgjengelig fra: 2015-09-25 Laget: 2015-09-25 Sist oppdatert: 2018-02-18bibliografisk kontrollert
  • 11.
    Skoglund, Björn
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi och idrottsmedicin. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Ortopedicentrum, Ortopedkliniken Linköping.
    Following the mevalonate pathway to bone heal alley2007Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The mevalonate pathway is an important biosynthetic pathway, found in all cells of virtually all known pro- as well as eukaryotic organisms. This thesis is an investigation into the use of two drugs, originally developed for different applications, but both affecting the mevalonate pathway, in to models of fracture repair.

    Using two different rodent models of fracture repair, a commonly used cholesterol lowering drug (statin) and two drugs used to treat osteoporosis (bisphosphonate) were applied both systemically as well as locally in order to enhance fracture repair.

    Papers I and II investigate the potential of simvastatin to improve the healing of femoral fractures in mice. Papers III and IV explore the use of two bisphosphonates to improve early fixation of stainless steel screws into rat bone.

    The statin simvastatin lead to an increased strength of the healing cellus. The application of bisphosphonates increased early screw fixation.

    It seems clear that both drugs have uses in orthopaedic applications. One interesting avenue of further research would be to combine the two classes of drugs and see if we can get the benefits while at the same time diminishing the drawbacks.

    Delarbeid
    1. Simvastatin Improves Fracture Healing in Mice
    Åpne denne publikasjonen i ny fane eller vindu >>Simvastatin Improves Fracture Healing in Mice
    2002 (engelsk)Inngår i: Journal of bone and mineral research, ISSN 0884-0431, Vol. 17, nr 111, s. 2004-2008Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Recently, several articles have been published dealing with the anabolic effects on bone by statins. Mundy and associates discovered that several statins were able to activate the promotor of bone morphogenetic protein (BMP) 2. Additionally, oral simvastatin and lovastatin increased the cancellous bone volume in rats, presumably an effect of the increase of BMP-2. Other studies have followed, with conflicting results; some have found a positive bone metabolic effect of statins and others have not. Studies published so far have focused on osteoporosis. In this study, femur fractures were produced in 81 mature male BALB/c mice and stabilized with marrow-nailing. Forty-one mice were given a diet prepared with simvastatin, so that each mouse received an approximate dose of 120 mg/kg of body weight per day. The remaining mice received the same diet with the exception of the simvastatin. Bilateral femurs were harvested at 8, 14, and 21 days postoperatively (po), the marrow-nail was extracted, and diameters were measured. Biomechanical tests were performed on 42 mice, by way of three-point bending. Histological specimens were prepared using standard techniques. For statistical analysis, ANOVA with Scheffé’s post hoc test was used. At 8 days, the fracture callus was too soft for meaningful biomechanical testing. At 14 days, the callus of the simvastatin-treated mice had a 53% larger transverse area than controls (p = 0.001), the force required to break the bone was 63% greater (p = 0.001), and the energy uptake was increased by 150% (p = 0.0008). Stiffness and modulus of elasticity were not significantly affected. At 21 days, the fractures were histologically healed and the mechanical differences had disappeared. The contralateral unbroken bone showed a slight increase in transverse area because of the simvastatin treatment, but there was no significant effect on the force required to break the bone or on energy uptake. These results point to a new possibility in the treatment of fractures.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13037 (URN)10.1359/jbmr.2002.17.11.2004 (DOI)
    Tilgjengelig fra: 2008-03-14 Laget: 2008-03-14 Sist oppdatert: 2009-06-04
    2. Locally applied Simvastatin Improves Fracture Healing in Mice
    Åpne denne publikasjonen i ny fane eller vindu >>Locally applied Simvastatin Improves Fracture Healing in Mice
    2007 (engelsk)Inngår i: BMC Musculoskeletal Disorders, ISSN 1471-2474, E-ISSN 1471-2474, Vol. 8, nr 98Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Background: HMG-CoA reductase inhibitors, statins, are widely prescribed to lower cholesterol. High doses of orally administered simvastatin has previously been shown to improve fracture healing in a mouse femur fracture model. In this study, simvastatin was administered either subcutaneously or directly to the fracture area, with the goal of stimulating fracture repair at acceptable doses.

    Methods: Femur fractures were produced in 70 mature male Balb-C mice and stabilized with marrow-nailing. Three experiments were performed. Firstly, 20 mice received subcutaneous injections of either simvastatin (20 mg) or vehicle. Secondly, 30 mice were divided into three groups of 10 mice receiving continuous subcutaneous delivery of the vehicle substance, the vehicle with 5 mg or with 10 mg of simvastatin per kg bodyweight per day. Finally, in 20 mice, a silicone tube was led from an osmotic mini-pump to the fracture area. In this way, 10 mice received an approximate local dose of simvastatin of 0.1 mg per kg per day for the duration of the experiment and 10 mice received the vehicle compound. All treatments lasted until the end of the experiment. Bilateral femurs were harvested 14 days post-operative. Biomechanical tests were performed by way of three-point bending. Data was analysed with ANOVA, Scheffé's post-hoc test and Student's unpaired t-test.

    Results: With daily simvastatin injections, no effects could be demonstrated for any of the parameters examined. Continuous systemic delivery resulted in a 160% larger force at failure. Continuous local delivery of simvastatin resulted in a 170% larger force at failure as well as a twofold larger energy uptake.

    Conclusion: This study found a dramatic positive effect on biomechanical parameters of fracture healing by simvastatin treatment directly applied to the fracture area.

    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13038 (URN)10.1186/1471-2474-8-98 (DOI)
    Tilgjengelig fra: 2009-02-22 Laget: 2009-02-22 Sist oppdatert: 2017-12-13bibliografisk kontrollert
    3. Systemic and Local Ibandronate Enhance Screw Fixation
    Åpne denne publikasjonen i ny fane eller vindu >>Systemic and Local Ibandronate Enhance Screw Fixation
    2004 (engelsk)Inngår i: Journal of Orthopaedic Reserach, ISSN 0736-0266, Vol. 22, nr 5, s. 1108-1113Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    The trauma involved with inserting implants into bone leads to an activation of the inflammatory response and an activation of osteoclasts. In addition, apoptosis of osteocytes in the surrounding area has been implicated in further activation of osteoclasts. If the balance between resorption and bone formation shortly after implantation favours resorption, an impairment of early fixation might ensue.Because bisphosphonates inhibit resorption, this study analyses whether they can improve early fixation. Stainless steel screws (M 1.7) were inserted into the tibiae of 76 male Sprague-Dawley rats. Daily subcutaneous injections of ibandronate (3 μg) or saline were given to 20 rats. The remaining rats received ibandronate or saline directly applied into the drill hole before the screw was inserted. Tibiae were harvested at 14 days. Mechanical tests were performed on 50 tibiae. Systemically treated tibiae were tested for pull-out strength alone. Locally treated tibiae were tested for either pull-out or torque resistance. The remaining 18 tibiae were prepared for histology.Systemic ibandronate increased the pull-out force at failure by 30% (p=0.04). Local treatment increased the force at failure by 15% (p=0.02) and stiffness by 28% (p=0.01). In the removal torque measurements, local ibandronate increased the torque-moment at failure by 60% (p=0.04), and the maximum friction moment by 51% (p=0.04). Energy for turning the screw 1/4 revolution was increased by 68% (p=0.02).These results demonstrate that early remodeling events plays an important role in screw fixation, and that systemic or local bisphosphonate treatment could be an effective pharmacological path to improve early implant fixation.

    Emneord
    Bisphosphonates, Implant, Fixation, Resorption
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13039 (URN)10.1016/j.orthres.2003.12.015 (DOI)
    Tilgjengelig fra: 2008-03-14 Laget: 2008-03-14 Sist oppdatert: 2009-08-21
    4. Surface Immobilized Bisphosphonate Improves Stainless-Steel Screw Fixation in Rats
    Åpne denne publikasjonen i ny fane eller vindu >>Surface Immobilized Bisphosphonate Improves Stainless-Steel Screw Fixation in Rats
    2004 (engelsk)Inngår i: Biomaterials, ISSN 0142-9612, Vol. 25, nr 11, s. 2133-2138Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    An increase in the mechanical fixation in bone of metallic biomaterials is considered advantageous in joint replacement and fracture surgery. Different approaches to improve fixation may be e.g. surface roughening, Ca-mineral coating or surface immobilization of growth factors or drugs. In the present work, bisphosphonate, a class of drugs that inhibit bone resorption, was immobilized onto stainless-steel screws.

    The screws were first roughened and coated with immobilized and cross-linked fibrinogen. Subsequently, an N-bisphosphonate, pamidronate, was immobilized onto fibrinogen, and another N-bisphosphonate, ibandronate, adsorbed on top of this. The so coated screws were inserted into the tibiae of eight male Sprague-Dawley rats. Another eight rats received screws prepared in the same way, but without the bisphosphonate coating. Pullout strength tests were performed after 2 weeks of implantation.

    The results showed a 28% (p=0.0009) higher pullout force and 90% increased pullout energy for the bisphosphonate coated screws, and support the idea that surface immobilized bisphosphonates can be used to improve biomaterials fixation in bone.

    Emneord
    Bisphosphonate, Immobilize, Bone, Pullout, Implant, Biomaterial
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-13040 (URN)10.1016/j.biomaterials.2003.08.049 (DOI)
    Tilgjengelig fra: 2008-03-14 Laget: 2008-03-14 Sist oppdatert: 2009-08-21
  • 12.
    Svensson, Catarina
    et al.
    Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Alvåsen, Karin
    Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Eldh, Ann Catrine
    Division of Nursing, Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden.
    Frössling, Jenny
    Department of Disease Control and Epidemiology, National Veterinary Institute, Uppsala, Sweden; Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara, Sweden.
    Lomander, H.
    District Veterinary Organization, Swedish Board of Agriculture, Tibro, Sweden.
    Veterinary herd health management: Experience among farmers and farm managers in Swedish dairy production2018Inngår i: Preventive Veterinary Medicine, ISSN 0167-5877, E-ISSN 1873-1716, Vol. 155, s. 45-52Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A preventive herd health approach will most likely reduce incidences of clinical and subclinical disease. Swedish veterinary organizations offer specific veterinary herd health management (HHM) programs, but these services are not used to a large extent.

    The aim of this study was to investigate dairy farmers’ experience of HHM and the conditions for collaboration with veterinarians in HHM.

    Six focus group discussions were conducted in March 2015 in West Sweden. In total, 33 dairy farmers participated. The recordings were transcribed and coded using thematic analysis, and the transcripts were reviewed to identify potential factors indicating barriers for farmers to engage a veterinarian in HHM. The participants reported HHM to be important, but they had difficulty defining the actions included in the concept. They described a wide range of their work duties as preventive. The farmers’ list of potential contributions by the veterinarians in HHM was strikingly short compared to the considerable number of preventive measures they performed themselves. Four main obstacles for farmers and farm managers to engage a veterinarian in HHM on their farm were identified in the analysis: “costs”, “veterinary knowledge, skills, and organization”, “farmer attitudes”, and “veterinarian-farmer relationships”. Costs were proposed as the main reason against engaging a veterinarian in HHM and included a high veterinary bill, low cost-benefit of veterinary services, and high costs to implement advice. Poor veterinary competence in HHM and poor knowledge about effective measures, practical farming, and farm economics were other important obstacles. Veterinarians were perceived to insufficiently describe their services and their benefits, and several participants felt they had never been offered veterinary HHM. Although veterinary HHM may be initiated by the farmer, the participants expected the veterinarian to have special responsibility for the initiation. A firm trust between farmer, staff, and veterinarian was considered crucial for veterinary HHM, but such trust takes a long time to build and can easily be disrupted by, for example, a veterinarian’s poor communication skills or lack of time.

    Our findings suggest that Swedish dairy farmers and herd managers find disease prevention important and that they perform a wide range of tasks to prevent disease in their animals. However, they do not see what role the veterinarian can play, and veterinarians were mainly associated with treating unhealthy cows. In order to increase the use of veterinary HHM programs the services and potential benefits of such programs need to be communicated more proactively.

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