| 21. |
- Abrahamson, Josefin
(författare)
-
Cam morphology of femoroacetabular impingement syndrome - Clinical, radiological and follow-up studies
- 2020
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Femoroacetabular impingement syndrome (FAIS) leads to hip pain and reduced hip function in young athletes. Recent studies have reported high-impact sporting activities during adolescent growth as an important cause of cam morphology. However, not all athletes with cam morphology develop symptoms and dysfunction related to FAIS, nor do they require surgical treatment. The question of why some athletes with cam morphology function well at a high level of sports for years, while others do not, and possible differences between genders and different sports, remains to be answered. The aim of this thesis is to investigate the correlation between cam morphology, hip joint range of motion (ROM) and hip pain in young elite athletes and patient-reported outcome measures (PROMs) and the rate of athletes still active at elite level after arthroscopic treatment for FAIS, and to make comparisons between genders, sports types and evaluations over time. Study I is a cross-sectional study comprising young athletes (60 male football players, 40 male and 35 female skiers). The prevalence of cam morphology, hip ROM, hip pain and FAIS is studied. Football players had reduced hip rotation compared with skiers, independent of cam morphology and hip pain. Male and female skiers had a higher proportion fulfilling the diagnostic criteria for FAIS compared with football players. Study II is a cohort study comparing hip ROM over 2 years in young skiers (n=30) with and without cam morphology. All the skiers reduced their hip rotation, independent of cam morphology. A statistical, not clinically relevant, larger reduction was shown in internal rotation in skiers with cam morphology. Study III is a cohort study investigating the correlation between cam morphology, activity level and hip pain over 5 years in young skiers (n=60). Activity level and cam morphology had no, or only a low, correlation with hip pain. Study IV is a cross-sectional study comprising 919 athletes undergoing arthroscopic treatment for FAIS. Preoperative PROMs and types of sport participation between genders is studied. Females had a longer duration and a higher degree of symptoms. Horseback riding and football were equally common in females, while football was dominant in males. Study V is a cohort study comprising 551 athletes undergoing arthroscopic treatment for FAIS. The rate of continued sporting activity is evaluated and compared between sports, genders and PROMs. Only 25% were still active at pre-injury level after 2 years, with no gender difference, but with a greater improvement in PROMs.
|
|
| 22. |
- Abrahamsson, Erik, 1974
(författare)
-
Atom-Diatom Scattering. From Potential Energy Surfaces to Rate Constants
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is about the theoretical study of collisions between atoms and diatomic molecules. It might seem like a trivial problem, but in reality it is a highly complex process. Despite, or because of, their apparent simplicity, these processes are of importance for a broad area of science. The applications stretch from the study of fundamental reactions at ultracold temperatures, through the far reaches of space, to the chemistry in the Earth’s atmosphere, and combustion at extreme temperatures. High-level ab initio methods (CASSCF/CASPT2) have been used to calculate potential energy surfaces in the linear 2Π and 4Σ−, and the non-linear 4A'' symmetry for the CNO system. The coupling between the collinear 2Π and 4Σ− surfaces has been calculated with the CASSCF/RASSI method. The collinear surfaces have been interpolated using a Generalized Discrete Variable Representation method to produce potential energy surfaces as functions of the nuclear coordinates, while the global 4A'' surface has been fitted to analytical functions using many-body expansion. Time-dependent wave packet and quasiclassical trajectory calculations are presented for the O + CN reaction on the two collinear surfaces, both with and without coupling between them. Quasiclassical trajectory calculations are presented for the C + NO reaction on the 4A'' potential energy surface. The results from the calculations for the C + NO reaction are combined with previously presented results for the 2A' and 2A'' surfaces, and compared with experiments. It is seen that the new 4A'' surface significantly improves the agreement with experiments. This is the first published study of the 4A'' surface for the CNO system. Time-independent quantum mechanical methods have been used to study the inelastic collision of various atomic and molecular systems, at temperatures ranging from the ultracold to 10 000 K. Rate constants for the fine-structure excitation in the C + H and O + H collisions are presented. These collisions are of interest in astrophysics, as the results can be used to study the chemical evolution in interstellar clouds. The fundamental and very important spin-orbit relaxation of F(2P1/2) and Cl(2P1/2) atoms in a gas of H2 is investigated, and cross sections and rate constants are presented. Scattering processes at low temperatures in external electric and magnetic fields are also studied. It is shown that the spin-orbit relaxation of polar molecules in a buffer gas of He can be effectively controlled by the field strengths and the angle between the fields, at temperatures easily reached in the lab. This is the first report of the effect of crossed electric and magnetic fields on scattering processes.
|
|
| 23. |
|
|
| 24. |
|
|
| 25. |
|
|
| 26. |
- Abrahamsson, Kajsa H., 1956
(författare)
-
Dental fear and oral health behavior. Studies on psychological and psychosocial factors
- 2003
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The general aim of this thesis was to study psychological and psychosocial factors in relation to the development, maintenance and expression of dental fear, how individuals cope with their fear, and how dental fear may impact on health and daily life. The study samples consisted of adult dental fear patients seeking treatment at a specialized dental fear clinic. Both quantitative and qualitative research methods were used. The qualitative interview protocols were analyzed using the constant comparative method of grounded theory. It was found that dental fear patients with concomitant high general fear differ in several ways from patients with less frequent and wide-spread fear. These differences concern dental fear reactions and related emotions, as well as general psychological dimensions. The results indicated an overall more negative and complex situation for patients with high dental and general fear. Comparisons between severe dental fear patients reporting different attendance patterns showed a higher education level and more filled teeth among patients with a history of regular dental care, while patients with phobic dental avoidance behavior had more anticipatory dental anxiety, more missing teeth, and reported a stronger negative impact from dental fear/poor oral status on daily life. General fearfulness was not related to phobic dental avoidance. According to the qualitative interviews the onset of dental fear was commonly related to an individual vulnerability and to traumatic dental care experiences, where perceived negative dentist behavior played a significant role. The patient was caught in a "vicious circle" that was difficult to break, and fear and anxiety were maintained by negative expectations about treatment and about the patient's own ability to cope in dental care situations. The interviews brought out the patients' ambivalence in coping with dental fear. The ambivalence was between, on the one hand the tendency to avoid dental care, and on the other hand the need for dental care and their attempt to find active problem-solving strategies. This left patients in a state of conflict with negative consequences for self-respect and well-being. It was obvious that dental fear and deteriorated oral health status resulted for many patients in wide-spread negative life consequences. It was also obvious that several psychological and social factors interact in determining how individuals cope with their dental fear, and demonstrate how dental fear affects their daily lives. Finally, the importance of dental beliefs in dental fear treatment was investigated. The interpretation of the results suggests that the assessment of dental beliefs provides valuable information and that patients' subjective perceptions about how dentists communicate are important for treatment outcome. However, initial dental beliefs were not found to predict clinical treatment outcome, and dental beliefs are one of several factors interacting in dental fear treatment. The results emphasize the complexity of dental fear and oral health behavior, where personality characteristics and environmental factors interact. This further elucidates the need for a broad-spectrum approach in dentistry.
|
|
| 27. |
- Abrahamsson, Therése, 1976
(författare)
-
Plasticity of the developing glutamate synapse in the hippocampus
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Synapses are highly plastic, i.e. they have the ability to change their signaling strength both in the short- and long-term (e.g. long-term potentiation - LTP) in response to specific patterns of activity. In the developing brain synaptic plasticity promotes activity-dependent development, whereas in the mature brain synaptic plasticity forms the basis for learning and memory. Although both development and learning involve organization and reorganization of synaptic circuits, the extent to which the plasticity behind these two phenomena uses the same mechanisms is unknown. The glutamate synapse which represents > 90 % of the brain synapses signals mainly via postsynaptic AMPA and NMDA receptors. In the developing brain, sparse synaptic activation can make the synapse lose its AMPA signaling capacity, i.e. make it AMPA silent, while LTP can reinstall the AMPA signaling (unsilencing). The aim of this study was to investigate the possible role of the AMPA silent synapse, and its unsilencing, in developmental and mature synaptic plasticity. Electrophysiological recordings of synaptic transmission in the CA1 region and in the dentate gyrus of acute hippocampal slices were used for these studies. A new and unexpected finding was that AMPA unsilencing can also be induced by not activating the AMPA silent synapse for tens of minutes. Together with previous findings this suggests a model in which the glutamate synapse is born with a single AMPA labile module, i.e. the synapse cycles between an AMPA silent state, induced by sparse synaptic activity, and an AMPA signaling state, induced by the absence of synaptic activity. The results further suggest that AMPA silencing is a prerequisite for developmental LTP to occur. In other words, developmental LTP does not potentiate synaptic transmission but rather stabilizes the AMPA labile module. It can, however, transiently potentiate the synapse by the addition of a labile AMPA module to an existing synapse with a single stable AMPA module. After this initial period of synaptic stabilization there is an increase in synaptic connectivity between pre- and postsynaptic neurons. It is proposed that this increased connectivity can be explained, at least partly, by the addition of stable AMPA modules to existing synapses promoted by mature LTP. This thesis thus proposes that, using the same principle mechanism, namely the addition of stable AMPA modules, developmental LTP promotes initial synaptic stabilization while mature LTP promotes synaptic growth.
|
|
| 28. |
- Abramova, Anna, 1990
(författare)
-
Molecular biology of barnacle Balanus improvisus settlement
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis was to investigate molecular mechanisms of various aspects of barnacle settlement, using the acorn barnacle Balanus improvisus. This barnacle is a common fouling species and a model organism for studies in settlement biology, in particular in relation to antifouling research. In order to facilitate the development of genomic resources in this species, we conducted a pilot study for the sequencing of the B. improvisus genome and performed an initial genomic characterization. The analysis revealed that B. improvisus genome has an extremely high genetic diversity, with about 5% nucleotide diversity in coding regions. In addition, we experimentally estimated the B. improvisus genome size, based on DNA staining and flow cytometry measurements, resulting in a haploid genome size of 738 Mbp. To investigate molecular changes during the settlement process, transcriptomes of four different settlement stages, ie free-swimming, closesearch, attached and juvenile, were compared. We identified several key genes involved in the hormonal regulation of molting and metamorphosis, including the broad complex, ecdysone receptor and retinoid X receptor, adding a new level of insight to the molecular mechanisms involved in settlement. Furthermore, we used two types of surfaces with different wettability to test if differences in surface preferences are reflected in gene expression. The results revealed that exploration of the “favourable” hydrophobic surface induced more genes and with larger changes in expression than on hydrophilic suggesting a stronger transcriptional response. We also investigated two specific aspects related to barnacle chemical communication during settlement - sensory receptors and pheromones. Analysis of the transcriptome of cyprid antennules resulted in the identification of two receptor classes, the chemosensory ionotropic receptors and mechanosensory receptors represented by several TRP subfamilies. We identified and characterized six homologs of the waterborne pheromone WSP in B. improvisus that showed differential expression during settlement. These results suggest the existence of a pheromone mix, where con-specificity might be determined by a combination of sequence characteristics and the concentration of the individual components. With the aim to further establish B. improvisus into a potent marine model system, a detailed protocol was developed for an all-year-round culturing of B. improvisus and adapted at Tjärnö Marine Laboratory. Finally, I summarise current knowledge on the molecular mechanisms of barnacle settlement and outline new research directions to further improve our understanding of the settlement biology of this species.
|
|
| 29. |
- Abramsson, Alexandra, 1973
(författare)
-
Tumor angiogenesis. Regulation of mural cell recruitment and endothelial sprouting
- 2003
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The formation of new blood vessels is an inherent part of many physiological and pathological processes. Currently, there is a strong hope pathological situations like stroke, diabetic retinopathy and cancer may be affected by pharmacological regulators of blood vessel formation. This thesis work has mainly been focused on two molecules implicated in blood vessel formation, platelet-derived growth factor (PDGF)-B and vascular endothelial growth factor (VEGF)-A. In vessels, PDGF-B is expressed by endothelial cells (EC) and act as a chemotactic and mitogenic signal via the PDGF receptor (PDGFR)-b on vascular smooth muscle cells (vSMC) and pericytes (PC). Tumor vessels are often abnormal and show a sparse association of vSMC/PC. We addressed the role of PDGF-B in vSMC/PC recruitment to tumor vessels using gain- and loss-of function analyses of PDGF-B. Our results show that vSMC/PC recruitment is dependent on PDGFRb and an EC source of PDGF-B. PDGF-B binds to the extracellular matrix in the close vicinity of EC through its retention motif. This spatial distribution of PDGF-B protein is needed for proper association of the PC with vessels; lack of PDGF-B retention leads to the extension of cellular processes away from the vessel, and to partial or complete PC detachment.VEGF-A stimulates migration and proliferation by binding to VEGF receptor expressed by EC. We have addressed the mechanism by which VEGF stimulate vessel formation by analyzing postnatal retinal vascularization. Our results revealed two functions of VEGF-A; guidance of highly specialized cells, tip-cells, at the tip of sprouting vessels, and proliferation of cells in the trailing cells, stalk-cells. Both these processes are mediated by VEGF receptor (VEGFR)-2. VEGF-A is produced in isoforms of 120, 164 or 188 amino acids where VEGF188 bind to the ECM, VEGF120 is soluble and VEGF164 has intermediate properties. Their spatial distribution creates a gradient sensed by filopodial extensions from the tip-cell. We also describe the existence of tip-cells with filopodia in tumors vessels. The extent of EC filopodia varies between tumors and correlates with vSMC/PC density and VEGF-A expression. Taken together, these results suggest that PDGF-B- and VEGF-A-stimulated processes in the vasculature are analogous. Migration of vSMC and EC seem to depend on the exact spatial distribution of PDGF-B and VEGF-A respectively. Proliferation of these cells on the other hand, appears to be regulated by the concentration of PDGF-B and VEGF-A. Our work also implies that anti-angiogenic therapy targeting VEGFR2 will inhibit the tip-cell and hence guided angiogenesis. The differences in sprouting phenotype in various tumors indicate that the angiogenic process of these tumors might differ. This, and variable vSMC/PC abundance in different tumors may implicate differences in responsiveness to anti-angiogenic therapy.
|
|
| 30. |
- Abzhandadze, Tamar, 1980
(författare)
-
Cognition and activity early after stroke
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introduction and aims: Cognitive impairment and dependency in activities of daily living (ADL) are common consequences of stroke. Due to a decrease in the length of hospital stay, assessment of these conditions has become necessary for the planning of discharge and rehabilitation. This thesis aimed to investigate the barriers to cognitive screening in acute stroke units, to understand whether cognitive impairment very early after stroke can explain ADL dependency at 36–48 h and three months after stroke, and to understand whether self-reported outcomes from a stroke register could be transformed into valid and reliable stroke scales. Methods: Four quantitative studies were conducted of which three were cross-sectional and one was a longitudinal study. Patients admitted to acute stroke units at Sahlgrenska University Hospital between 2011 and 2018 were included in the study. Two stroke registries and one research database were used during the analysis. Cognition and ADL were evaluated while the patients were in an acute stroke unit. Three-month follow-up data were gathered via self-reported questionnaires, telephone interviews, and/or physician visits. Agreement, correlation, classification, and regression analyses were also conducted for the chosen data. Results: The sample size varied between 305 and 1,145 patients. A small majority of the included patients were men (54–59%). The median age of the patients ranged from 70 to 74 years. Most patients had mild stroke severity. Variables encompassing impaired body functions, activity limitations, worsened health conditions, and environmental factors explained barriers to cognitive screening in acute stroke units. Furthermore, cognitive impairment within 36–48 h after admission to the stroke units could explain ADL dependency two days and three months later. Self-reported questions about ADL three months after stroke could be transformed into a valid clinical scale to assess global disability after stroke. Conclusions: The barriers to cognitive screening can be both, patient-and organization-related. Cognitive function screened very early after stroke can be used to expand ADL dependency. Self-reported questions can be transformed into valid and reliable stroke scales using various techniques. However, it is important to note that, as the study results are based on SU cohorts, external validation is needed to strengthen the conclusions.
|
|
