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Search Results: 1 - 10 of 1775 matches for " Kristina Karlsson "
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Phenotypic Plasticity in Response to the Social Environment: Effects of Density and Sex Ratio on Mating Behaviour Following Ecotype Divergence
Kristina Karlsson,Fabrice Eroukhmanoff,Erik I. Svensson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0012755
Abstract: The ability to express phenotypically plastic responses to environmental cues might be adaptive in changing environments. We studied phenotypic plasticity in mating behaviour as a response to population density and adult sex ratio in a freshwater isopod (Asellus aquaticus). A. aquaticus has recently diverged into two distinct ecotypes, inhabiting different lake habitats (reed Phragmites australis and stonewort Chara tomentosa, respectively). In field surveys, we found that these habitats differ markedly in isopod population densities and adult sex ratios. These spatially and temporally demographic differences are likely to affect mating behaviour. We performed behavioural experiments using animals from both the ancestral ecotype (“reed” isopods) and from the novel ecotype (“stonewort” isopods) population. We found that neither ecotype adjusted their behaviour in response to population density. However, the reed ecotype had a higher intrinsic mating propensity across densities. In contrast to the effects of density, we found ecotype differences in plasticity in response to sex ratio. The stonewort ecotype show pronounced phenotypic plasticity in mating propensity to adult sex ratio, whereas the reed ecotype showed a more canalised behaviour with respect to this demographic factor. We suggest that the lower overall mating propensity and the phenotypic plasticity in response to sex ratio have evolved in the novel stonewort ecotype following invasion of the novel habitat. Plasticity in mating behaviour may in turn have effects on the direction and intensity of sexual selection in the stonewort habitat, which may fuel further ecotype divergence.
The Semantic Representation of Event Information Depends on the Cue Modality: An Instance of Meaning-Based Retrieval
Kristina Karlsson, Sverker Sikstr?m, Johan Willander
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0073378
Abstract: The semantic content, or the meaning, is the essence of autobiographical memories. In comparison to previous research, which has mainly focused on the phenomenological experience and the age distribution of retrieved events, the present study provides a novel view on the retrieval of event information by quantifying the information as semantic representations. We investigated the semantic representation of sensory cued autobiographical events and studied the modality hierarchy within the multimodal retrieval cues. The experiment comprised a cued recall task, where the participants were presented with visual, auditory, olfactory or multimodal retrieval cues and asked to recall autobiographical events. The results indicated that the three different unimodal retrieval cues generate significantly different semantic representations. Further, the auditory and the visual modalities contributed the most to the semantic representation of the multimodally retrieved events. Finally, the semantic representation of the multimodal condition could be described as a combination of the three unimodal conditions. In conclusion, these results suggest that the meaning of the retrieved event information depends on the modality of the retrieval cues.
Does the peak torque of the hamstring and quadriceps muscles affect the knee laxity measurements in male patients with anterior cruciate ligament rupture?
Ninni Sernert,Jüri Kartus,Kristina K hler,Lars Ejerhed,Sveinbj rn Brandsson,Jon Karlsson
Journal of Orthopaedics and Traumatology , 2000, DOI: 10.1007/s101950070003
Abstract: The aim of the study was to examine whether the peak torque of the hamstring and quadriceps muscles affects the anterior knee laxity measurements in male patients. The study comprised 45 male patients who had a chronic unilateral anterior cruciate ligament (ACL) rupture. Preoperatively, one experienced physiotherapist performed all the KT-1000 examinations. The anterior displacement was registered at 89 Newton. Immediately after the KT-1000 examination, an isokinetic concentric peak torque measurement was performed at 60°/s for both the hamstring and quadriceps muscles. The anterior displacement was significantly larger in the ACL-ruptured knees compared with the noninjured knees (p < 0.001). Patients with strong hamstring muscles on the injured side displayed significantly less knee laxity compared with patients with less strength (p = 0.018). There was an inverse correlation between the peak torque of the hamstring muscles and the KT-1000 anterior laxity measurements in the ACL-ruptured knees (rho = 0.37, p = 0.01). We conclude that male patients with strong hamstring muscles display smaller KT-1000 laxity measurements than patients with less strength.
Thymidine Kinase 2 Deficiency-Induced mtDNA Depletion in Mouse Liver Leads to Defect β-Oxidation
Xiaoshan Zhou, Kristina Kannisto, Sophie Curbo, Ulrika von D?beln, Kjell Hultenby, Sindra Isetun, Mats G?fvels, Anna Karlsson
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0058843
Abstract: Thymidine kinase 2 (TK2) deficiency in humans causes mitochondrial DNA (mtDNA) depletion syndrome. To study the molecular mechanisms underlying the disease and search for treatment options, we previously generated and described a TK2 deficient mouse strain (TK2?/?) that progressively loses its mtDNA. The TK2?/? mouse model displays symptoms similar to humans harboring TK2 deficient infantile fatal encephalomyopathy. Here, we have studied the TK2?/? mouse model to clarify the pathological role of progressive mtDNA depletion in liver for the severe outcome of TK2 deficiency. We observed that a gradual depletion of mtDNA in the liver of the TK2?/? mice was accompanied by increasingly hypertrophic mitochondria and accumulation of fat vesicles in the liver cells. The levels of cholesterol and nonesterified fatty acids were elevated and there was accumulation of long chain acylcarnitines in plasma of the TK2?/? mice. In mice with hepatic mtDNA levels below 20%, the blood sugar and the ketone levels dropped. These mice also exhibited reduced mitochondrial β-oxidation due to decreased transport of long chain acylcarnitines into the mitochondria. The gradual loss of mtDNA in the liver of the TK2?/? mice causes impaired mitochondrial function that leads to defect β-oxidation and, as a result, insufficient production of ketone bodies and glucose. This study provides insight into the mechanism of encephalomyopathy caused by TK2 deficiency-induced mtDNA depletion that may be used to explore novel therapeutic strategies.
Iron-Restricted Erythropoiesis in a Population of Elderly Hospitalized Anemic Patients  [PDF]
Torbj?rn Karlsson
Open Journal of Blood Diseases (OJBD) , 2012, DOI: 10.4236/ojbd.2012.22006
Abstract: The aim of this observational study was to assess the prevalence of iron-restricted erythropoiesis (IRE) in a population of elderly hospitalized anemic patients. Prevalence of IRE was found to be 41% and the most common clinical diagnoses in such patients were hematologic malignancies and solid tumors. Comparison between patients with IRE and non-IRE patients revealed that mean corpuscular volume, mean corpuscular hemoglobin, iron, and transferrin saturation were significantly lower in the IRE group, whereas no significant difference was found for Hb, transferrin, or ferritin. There was a more pronounced inflammatory response in the IRE group demonstrated by a higher C-reactive protein level.
Iron-Restricted Erythropoiesis in Anaemic Patients with Giant Cell Arteritis and Polymyalgia Rheumatica  [PDF]
Torbj?rn Karlsson
Open Journal of Blood Diseases (OJBD) , 2013, DOI: 10.4236/ojbd.2013.31010
Abstract:

The aim of this observational study was to biochemically characterize the anaemia in GCA (giant cell arteritis) and PMR (polymyalgia rheumatica) patients. Values for mean corpuscular volume, mean corpuscular hemoglobin and soluble transferrin receptor were normal, whereas serum iron and total iron binding capacity (TIBC) were subnormal, and mean ferritin was above the upper reference limit. Iron-restricted erythropoiesis (IRE), defined as a bone marrow smear staining positive for iron in combination with transferrin saturation less than 20%, was present in all patients. All patients exhibited clinical and biochemical signs of active inflammation with elevated C-reactive protein and an increased erythrocyte sedimentation rate.

Arachidonate 15-Lipoxygenase Type B Knockdown Leads to Reduced Lipid Accumulation and Inflammation in Atherosclerosis
Lisa U. Magnusson, Annika Lundqvist, Merja Nurkkala Karlsson, Kristina Sk?lén, Max Levin, Olov Wiklund, Jan Borén, Lillemor Mattsson Hultén
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043142
Abstract: Inflammation in the vascular wall is important for development of atherosclerosis. We have shown previously that arachidonate 15-lipoxygenase type B (ALOX15B) is more highly expressed in human atherosclerotic lesions than in healthy arteries. This enzyme oxidizes fatty acids to substances that promote local inflammation and is expressed in lipid-loaded macrophages (foam cells) present in the atherosclerotic lesions. Here, we investigated the role of ALOX15B in foam cell formation in human primary macrophages and found that silencing of human ALOX15B decreased cellular lipid accumulation as well as proinflammatory cytokine secretion from macrophages. To investigate the role of ALOX15B in promoting the development of atherosclerosis in vivo, we used lentiviral shRNA silencing and bone marrow transplantation to knockdown mouse Alox15b gene expression in LDL-receptor-deficient (Ldlr?/?) mice. Knockdown of mouse Alox15b in vivo decreased plaque lipid content and markers of inflammation. In summary, we have shown that ALOX15B influences progression of atherosclerosis, indicating that this enzyme has an active proatherogenic role.
Up-regulation of cell cycle arrest protein BTG2 correlates with increased overall survival in breast cancer, as detected by immunohistochemistry using tissue microarray
Elin M?llerstr?m, Anikó Kovács, Kristina L?vgren, Szilard Nemes, Ulla Delle, Anna Danielsson, Toshima Parris, Donal J Brennan, Karin Jirstr?m, Per Karlsson, Khalil Helou
BMC Cancer , 2010, DOI: 10.1186/1471-2407-10-296
Abstract: Protein expression was evaluated using immunohistochemistry in an independent breast cancer cohort of 144 samples represented on tissue microarrays. Fisher's exact test was used to analyze the differences in protein expression between dead and alive patients. We used Cox-regression multivariate analysis to assess whether the new markers predict the survival status of the patients better than the currently used markers.BTG2 expression was demonstrated in a significantly lower proportion of samples from dead patients compared to alive patients, both in overall expression (P = 0.026) and cell membrane specific expression (P = 0.013), whereas neither ADIPOR1, ADORA1 nor CD46 showed differential expression in the two survival groups. Furthermore, a multivariate analysis showed that a model containing BTG2 expression in combination with HER2 and Ki67 expression along with patient age performed better than a model containing the currently used prognostic markers (tumour size, nodal status, HER2 expression, hormone receptor status, histological grade, and patient age). Interestingly, BTG2 has previously been described as a tumour suppressor gene involved in cell cycle arrest and p53 signalling.We conclude that high-level BTG2 protein expression correlates with prolonged survival in patients with breast carcinoma.Breast cancer is the most common malignancy among women, and accounted for approximately 1.15 million new cases and 411,000 deaths worldwide in 2002 [1]. During the last decade, the survival rate for breast cancer patients has increased dramatically due to earlier detection and new treatment protocols [2]. Presently, various clinical and pathological markers including axillary lymph node status, hormone receptor status, histological grade, tumour size, patient age, HER2 expression and vascular invasion are used to predict breast cancer prognosis and provide accurate treatment [3]. However, these markers are insufficient and approximately 20 to 30% of breast cancer p
Doing Care with Integrity and Emotional Sensibility—Reciprocal Encounters in Psychiatric Community Care of Older People with Mental Health Problems  [PDF]
Lis Bodil Karlsson, Elisabeth Rydwik
Sociology Mind (SM) , 2013, DOI: 10.4236/sm.2013.32025
Abstract:

The article focuses on the experiences of community care workers in the encounter with older persons suffering from mental health problems, such as mental illness and disability. The purpose is to describe and discuss opportunities for and challenges to reciprocal encounters with these older people in community care, based on statements from professionals interviewed. Structured conversations with five focus groups were organised, consisting of 26 participants, including nurses’ assistants, assistant nurses, nurses, social workers and occupational therapists. The participants in the focus groups highlight the essence of being involved and create space for a reflective attitude. Clinical implications will be presented as well.

Minimization of the Expected Total Net Loss in a Stationary Multistate Flow Network System  [PDF]
Kristina Skutlaberg, Bent Natvig
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.78071
Abstract: In the present paper, a three-component, stationary, multistate flow network system is studied. Detailed costs and incomes are specified. The aim is to minimize the expected total net loss with respect to the expected times the components spend in each state. This represents a novelty in that we connect the expected component times spent in each state to the minimal total net loss of the system, without first finding the component importance. This is of interest in the design phase where one may tune the components to minimize the expected total net loss. Due to the complex nature of the problem, we first study a simplified version. There the expected times spent in each state are assumed equal for each component. Then a modified version of the full model is presented. The optimization in this model is completed in two steps. First the optimization is carried out for a set of pre-chosen fixed expected life cycle lengths. Then the overall minimum is identified by varying these expectations. Both the simplified and the modified optimization problems are nonlinear. The setup used in this article is such that it can easily be modified to represent other flow network systems and cost functions. The challenge lies in the optimization of real life systems.
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