| 1. |
- Andersson, Jonas, 1975-
(författare)
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Ion recombination in liquid ionization chambers : development of an experimental method to quantify general recombination
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An experimental method (the two-dose-rate method) for the correction of general recombination losses in liquid ionization chambers has been developed and employed in experiments with different liquids and radiation qualities. The method is based on a disassociation of initial and general recombination, since an ionized liquid is simultaneously affected by both of these processes.The two-dose-rate method has been compared to an existing method for general recombination correction for liquid ionization chambers, and has been found to be the most robust method presently available.The soundness of modelling general recombination in liquids on existing theory for gases has been evaluated, and experiments indicate that the process of general recombination is similar in a gas and a liquid. It is thus reasonable to employ theory for gases in the two-dose-rate method to achieve experimental corrections for general recombination in liquids. There are uncertainties in the disassociation of initial and general recombination in the two-dose-rate method for low applied voltages, where initial recombination has been found to cause deviating results for different liquids and radiation qualities.Sensitivity to ambient electric fields has been identified in the microLion liquid ionization chamber (PTW, Germany). Experimental data may thus be perturbed if measurements are conducted in the presence of ambient electric fields, and the sensitivity has been found to increase with an increase in the applied voltage. This can prove to be experimentally limiting since general recombination may be too severe for accurate corrections if the applied voltage is low.
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| 2. |
- Antonsson, Helena, 1962-
(författare)
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Interaktion i särskilt boende för personer med utvecklingsstörning och utmanande beteende
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bakgrund: Många personer med utvecklingsstörning har kommunikativa svårigheter och har därför behov av att utveckla olika sätt att kommunicera för att kunna förstå andra och göra sig förstådda. Svårigheter i kommunikationen påverkar interaktionen mellan personer med utvecklingsstörning och deras vårdare. Detta ställer höga krav på vårdare att kunna tolka och förstå den enskilda individens sätt att uttrycka önskningar och behov. På samma sätt riskerar vårdares budskap att missförstås. Om vårdaren misslyckas att förstå den boendes kommunikation och vice versa, kan det leda till situationer med utmanande beteende exempelvis i form av vägran, verbal eller fysisk aggressivitet.Syfte: Det övergripande syftet med avhandlingen är att studera interaktion mellan vuxna personer med utvecklingsstörning och vårdare i gruppbostäder, samt att studera effekter av en utbildningsintervention för vårdare som arbetar i gruppbostäder.Metod: Avhandlingens samtliga delstudier har genomförts i gruppbostäder för personer med utvecklingsstörning bland boende och vårdare i ett län i norra Sverige. I studie I insamlades data kring 556 personer med utvecklingsstörning. I studie II och III deltog 16 vårdare och 11 personer med utvecklingsstörning. I studie IV deltog 7 vårdare. Studie I bygger på personalens skattningar av funktionsnivåer och förekomst av begränsningsåtgärder. I Studie II och III utgörs data av videoobservationer och narrativa intervjuer. I studie IV användes flera datainsamlingsmetoder i en mixed method design med både vårdarnas skattningar, med hjälp av instrument och semi-strukturerade intervjuer. Analys av materialet i studie II, III och IV har gjorts med kvalitativ innehållsanalys och i studie I och IV har data analyserats statistiskt.Resultat: I studie I framkom att av 556 boende hade 99 (18%) varit föremål för fysiska begränsningsåtgärder under den senaste veckan. Av dessa 99 hade nästan alla varit föremål för mer än en typ av begränsningsåtgärd. Den vanligaste begränsningsåtgärden var bälte i stol (74%). Användningen av begränsningsåtgärder var relaterade både till fysiska funktionsnedsättningar och till beteende.I studie II reflekterade vårdare över videoinspelad interaktion där vårdarna medverkat, både framgångsrik och misslyckad interaktion. Exempel på framgångsrik interaktion var att förstå tecken, kunna möta behov och hantera situationer med utmanande beteenden. Vårdarna reflekterade över att framgångsrik interaktion ledde till säkerhet, trygghet och självförtroende hos de boende. Vårdarna reflekterade även över de konsekvenser misslyckad interaktion fick i form av irritation, aggression och våld från de boende.I studie III studerades videoinspelad interaktion mellan 11 personer med utvecklingsstörning och 16 av deras vårdare. Verbal och icke-verbal interaktion identifierades. Fyra inspelade situationer valdes ut för att belysa framgångsrikt samspel. Resultatet visade att framgångsrikt samspel mellan personer med utvecklingsstörning och deras vårdare bland annat bygger på möjligheten att bekräfta varandra, dela vardagshändelser, ge tid och utrymme och på att använda ett kongruent och tydligt språk.I studie IV utvärderades effekterna av en web-baserad utbildningsintervention, vars syfte var att förbättra interaktionen mellan personer med utvecklingsstörning och vårdare samt att därmed reducera förekomsten av situationer med utmanande beteende. Resultatet visade att vårdarna hade förbättrat sin förmåga att hantera situationer med utmanande beteende och att förekomsten av utmanande beteende minskat. Vårdarna beskrev att den web-baserade utbildningen upplevts givande och möjlig att ta del av parallellt med arbetet.Slutsats: Fysiska begränsningsåtgärder förekommer i gruppbostäder för personer med utvecklingsstörning. Användningen av begränsningsåtgärder kan vara relaterade både till fysiska funktionsnedsättningar och till beteenden i samspelet mellan brukare och vårdare. Vårdare upplever användningen av fysiska begränsningsåtgärder svår och tröttande. Brott i kommunikationen mellan personer med utvecklingsstörning och deras vårdare kan leda till försvårad interaktion med risk för situationer med utmanande beteenden. När vårdare är framgångsrika i interaktionen med personer med utvecklingsstörning ger det tillfredsställelse både för de boende och vårdarna. Vårdarna upplever dock ofta hjälplöshet och osäkerhet i relation till hantering av situationer med utmanande beteende och efterfrågar utbildning. Web-baserad utbildning om interaktion med personer med utvecklingsstörning och utmanande beteende har i vår studie visat sig ge lovande effekter och bör vara möjlig att utveckla för både introduktion av nyanställda vårdare och för kompetensutveckling bland mer erfaren personal.
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| 3. |
- Axelsson, Birger, 1957-
(författare)
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Cardiac effects of non-adrenergic inotropic drugs : clinical and experimental studies
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Myocardial failure and dysfunction is not uncommon during critical illness and following cardiac surgery. For optimal treatment, a better understanding of the effects of inotropic drugs is needed. In this thesis, two non-adrenergic mediated inotropes, milrinone and levosimendan were studied in different models of myocardial dysfunction. The study aims were to assess the following: the effects of milrinone on blood flow in coronary artery bypass grafts during CABG surgery; the effects of milrinone on left ventricular diastolic function during post-ischaemic myocardial dysfunction; whether milrinone or levosimendan are protective or injurious during acute myocardial ischaemia, and if levosimendan potentiates myocardial function when added to milrinone in an experimental model of post-ischaemic (stunned) myocardium.Material and Methods: In Study I, 44 patients undergoing coronary artery bypass surgery(CABG) were included as subjects. Milrinone or saline was administrated in a single dose during cardio-pulmonary bypass (CPB) and coronary graft flow measurements were recorded after 10 and 30 min following CPB. In Study II; 24 patients undergoing CABG had estimations of peak ventricular filling rates made before and after CPB with administration of milrinone or saline as a single dose during CPB, performed by assessment of the rate of change in diastolic cross-sectional left ventricular area. In Study III, energy-metabolic effects of milrinone and levosimendan were measured in an anaesthetized porcine model during 45 minutes of regional myocardial ischemia. Microdialysis sampling of metabolites of local ischemic metabolism allowed assessment of glycolytic activity and the degree of myocardial calcium overload. In Study IV, in a porcine model of postischaemic myocardial stunning, ventricular pressure-volume relationships were analyzed when milrinone or a combination of milrinone and levosimendan were given together.Results: In Study I, there was a clear increase in non-sequential saphenous vein graft blood flow with milrinone at 10 minutes (64.5 ± 37.4 compared to placebo 43.6 ± 25.7 ml/min (mean ± SD).). A decreasing but still measureable flow increase was seen for milrinone at 30 minutes. In Study II, an increase in early left ventricular filling rate (ventricular cross-sectional area rate of change,dA/dt) was seen in the milrinone treated group. Pre-bypass milrinone group dA/dt 22.0 ± 9.5 changed to post-bypass values dA/dt 27.8 ± 11.5 cm2/sec). Placebo group pre-bypass dA/dt was 21.0 ± 8.7 and post-bypass 17.1 ± 7.1 cm2/sec. A milrinone effect was demonstrated in an adjusted regression model (p = 0.001). In Study III, neither milrinone nor levosimendan led to a change in energy-metabolic activity during ischemia as reflected by interstitial glucose, pyruvate, lactate orglycerol. Neither drug exacerbated the relative myocardial calcium overload during ischemia. In Study IV, milrinone improved active relaxation (tau) in post-ischemic stunned myocardium, but did not markedly improve systolic function by preload recruitable stroke work. Levosimendan added to milrinone showed minimal effect on active relaxation but a positive effect on systolic function in combination with milrinone.Conclusions: We conclude that milrinone treatment leads to an increase in blood flow in newly implanted coronary saphenous vein grafts, and improves ventricular relaxation post-cardiopulmonary bypass. Neither milrinone nor levosimendan, in this porcine model, negatively influence myocardial energy metabolism or calcium overload during acute ischaemia. Addition of levosimendan to milrinone treatment during post-ischaemic ventricular dysfunction may provide additive inotropic effects on systolic function but probably not for active relaxation.
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| 4. |
- Backman, Ludvig, 1983-
(författare)
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Neuropeptide and catecholamine effects on tenocytes in tendinosis development : studies on two model systems with focus on proliferation and apoptosis
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Achilles tendinopathy is a common clinical syndrome of chronic Achilles tendon pain combined with thickening of the tendon and impaired tendon function. Tendinopathy is often, but not always, induced by mechanical overload, and is frequently accompanied by abnormalities at the tissue level, such as hypercellularity and angiogenesis, in which case the condition is called tendinosis. In tendinosis, there are no signs of intratendinous inflammation, but occasionally increased apoptosis is observed. Tendinosis is often hard to treat and its pathogenesis is still not clear. Recently, a new hypothesis has gained support, suggesting a biochemical model based on the presence of a non-neuronal production of classically neuronal signal substances by the primary tendon cells (tenocytes) in tendinosis. The possible functional importance of these signal substances in tendons is unknown and needs to be studied. In particular, the neuropeptide substance P (SP) and catecholamines are of interest in this regard, since these substances have been found to be up-regulated in tendinosis. As both SP and catecholamines are known to exert effects in other tissues resulting in changes similar to those characteristic of tendinosis, it is possible that they have a role in tendinosis development. It is furthermore unknown what elicits the increased intratendinous neuropeptide production in tendinosis, but given that tendon overload is a prominent riskfactor, it is possible that mechanical stimuli are involved.The hypothesis of this thesis work was that intratendinous production of SP is up-regulated in response to load of Achilles tendons/tenocytes, and thatstimulation of the preferred SP receptor, the neurokinin-1 receptor (NK-1 R), aswell as stimulation of the catecholamine α2 adrenoreceptors, contribute to the hypercellularity seen in tendinosis, via increased proliferation and/or decreased apoptosis, and that SP stimulates tendon angiogenesis. The purpose of the studies was to test this hypothesis. To achieve this, two model systems were used: One in vivo (rabbit Achilles tendon overload model of tendinosis) and one in vitro (human primary Achilles tendon cell culture model).Results: In the rabbit Achilles tendon tissue, SP and NK-1 R expression was extensive in the blood vessel walls, but also to some extent seen in the tenocytes. Quantification of endogenously produced SP in vivo confirmed intratendinous production of the peptide. The production of SP by human tendon cells in vitro was furthermore demonstrated. The catecholamine synthesizing enzyme tyrosine hydroxylase (TH), as well as the α2A adrenoreceptor (α2A AR), were detected in the tenocytes, both in vivo in the rabbit tissue and in vitro in the human tendon cells. As a response to mechanical loading in the in vivo model, the intratendinous levels of SP increased, and this elevation was found to precede distinct tendinosis changes. The in vitro model demonstrated the same response to load, i.e. an increased SP expression, but in this case also a decrease in the NK-1 R expression. In the in vivo model, exogenously administered SP, as well as clonidine (an α2 AR agonist), accelerated tenocyte hypercellularity, an effect that was not seen when administrating a specific α2A AR antagonist. Exogenous administration of SP also resulted in intratendinous angiogenesis and paratendinous inflammation. In the in vitro model, both SP and clonidine had proliferative effects on the human tenocytes, specifically mediated via NK-1R and α2A AR, respectively; both of which in turn involved activation/phosphorylation of the extracellular signal-regulated kinases 1 and 2 (ERK1/2). Exogenously administered SP, in Anti-Fas induced apoptosis of the tenocytes in vitro, confirmed SP to have an anti-apoptotic effect on these cells. This effect was specifically mediated via NK-1 R and the known anti-apoptotic Akt pathway.Conclusions: In summary, this thesis concludes that stimulation of NK-1 R and α2A AR on tenocytes, both in vitro and in vivo, mediates significant cell signalling effects leading to processes known to occur in tendinosis, including hypercellularity. The pathological role of the hypercellularity in tendinosis is still unclear, but it is likely to affect collagen metabolism/turnover and arrangement, and thereby indirectly tendon biomechanical function. Additional evidence is here provided showing that SP not only causes tenocyte proliferation, but also contributes to anti-apoptotic events. Furthermore, it was concluded that SP may be involved in the development of tendinosis, since its production is increased in response to load, preceding tendinosis, and since SP accelerates tendinosis changes, through some mechanistic pathways here delineated. These findings suggest that inhibition of SP, and possibly also catecholamines, could be beneficial in the reconstitution/normalization of tendon structure in tendinosis.
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| 5. |
- Backteman-Erlanson, Susann, 1958-
(författare)
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Burnout, work, stress of conscience and coping among female and male patrolling police officers
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background. Police work is a stressful occupation with frequent exposure to traumatic events and psychological strain from work might increase the risk of burnout. This thesis focuses on patrolling police officers (PPO), who work most of their time in the community and have daily contact with the public. Since police work traditionally is a male coded occupation we assume that there are differences between women and men in burnout as well as experiences from psychosocial work environment.Aim. The overall aim of this thesis is to explore burnout, psychosocial and physical work environment, coping strategies, and stress of conscience when taking gender into consideration among patrolling police officers.Methods. This thesis employs both qualitative and quantitative methods. In Paper I a qualitative approach with narrative interviews was used where male PPO described experiences of traumatic situations when caring for victims of traffic accidents. A convenience sample of nine male PPO from a mid-sized police authority was recruited. Interviews were analyzed using qualitative content analysis. Papers II, III, and IV were based on a cross-sectional survey from a randomly selected sample stratified for gender from all 21 local police authorities in Sweden. In the final sample, 1554 PPOs were invited (778 women, 776 men), response rate was 55% (n=856) in total, 56% for women (n=437) and 53% for men (n=419). The survey included a self-administered questionnaire based on instruments measuring burnout, stress of conscience, psychosocial and physical work environment, and coping.Results. Findings from Paper I were presented in three themes; “being secure with the support system,” “being confident about prior successful actions,” and “being burdened with uncertainty.” Results from Paper II showed high levels of emotional exhaustion (EE), 30% for female PPOs and 26% for male PPOs. High levels of depersonalization (DP) were reported for 52 % of female PPO, corresponding proportions for male were 60%. Multiple logistic regression showed that stress of conscience (SCQ-A), high demand, and organizational climate increased the risk of EE for female PPO. For male PPO stress of conscience (SCQ-A), low control and high demand increased the risk of EE. Independent of gender, stress of conscience (SCQ-A) increased the risk of DP. Psychometric properties of the WOCQ were investigated with exploratory factor analysis and confirmatory factor analysis, a six-factor solution was confirmed. DIF analysis was detected for a third of the items in relation to gender. In Paper IV a block wise hierarchical multiple regression analysis was performed investigating the predictive impact of psychological demand, decision latitude, social support, coping strategies, and stress of conscience on EE as well as DP. Findings revealed that, regardless of gender, risk of EE and DP increased with a troubled conscience amongst the PPO.Conclusion. “Being burdened with uncertainty” in this male-dominated context indicate that the PPO did not feel confident talking about traumatic situations, which might influence their coping strategies when arriving to a similar situation. This finding can be related to Paper II and IV showing that stress of conscience increased the risk of both EE and DP. The associations between troubled conscience and the risk of experiencing both emotional exhaustion and depersonalization indicate that stress of conscience should be considered when studying the influence of the psychosocial work environment on burnout. Results from this study show that the psychosocial work environment is not satisfying and needs improvement for patrolling police officers in Sweden. Further studies including both qualitative and quantitative (longitudinal) methods should be used to improve knowledge in this area to increase conditions for preventive and rehabilitative actions.
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| 6. |
- Bagge, Johan, 1984-
(författare)
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TNF-α and neurotrophins in Achilles tendinosis
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tenocytes are the principal cells of the human Achilles tendon. In tendinosis, changes in the metabolism and morphology of these cells occur. Neurotrophins are growth factors essential for the development of the nervous system. Tumour necrosis factor alpha (TNF-α) has been found to kill sarcomas but has destructive effects in several major diseases. The two systems have interaction effects and are associated with apoptosis, proliferation, and pain signalling in various diseases. Whether these systems are present in the Achilles tendon and in Achilles tendinosis is unknown. The hypothesis is that the tenocytes produce substances belonging to these systems. In Studies I–III, we show that the potent effects of these substances are also likely to occur in the Achilles tendon. We found tenocyte immunoreactions for the neurotrophins brain-derived neurotrophic factor (BDNF), the nerve growth factor (NGF), the neurotrophin receptor p75, and for TNF-α and both of its receptors, TNFR1 and TNFR2. This occurred in both subjects with painful mid-portion Achilles tendinosis, and in controls. Furthermore, we found mRNA expression for BDNF and TNF-α in tenocytes, which proves that these cells produce these substances. TNFR1 mRNA was also detected for the tenocytes, and TNFR1 immunoreactions were upregulated in tendinosis tendons. This might explain why tenocytes in tendinosis undergo apoptosis more often than in normal tendons. Total physical activity (TPA) level and blood concentration of both soluble TNFR1 and BDNF were measured in Study IV. The results showed that the blood concentration of both factors were similar in subjects with tendinosis and in controls. Nevertheless, the TPA level was related to the blood concentration of sTNFR1 in tendinosis, but not in controls. This relationship should be studied further. The findings of this doctoral thesis show that neurotrophin and TNF-α systems are expressed in the Achilles tendon. We believe that the functions include tissue remodelling, proliferation and apoptosis.
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| 7. |
- Bengtsson, Sara, 1978-
(författare)
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Stress steroids as accelerators of Alzheimer's disease. : Effects of chronically elevated levels of allopregnanolone in transgenic AD models.
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background Alzheimer’s disease (AD) and dementia are devastating conditions not only for the affected patients but also for their families. The economical costs for the society are tremendous. Mid-life psychological stress, psychosocial stress and post-traumatic stress disorder cause cognitive dysfunction and lead to increased risk for dementia. However, the mechanisms behind stress-induced AD and dementia are not known. AD is characterized by solid amyloid plaques in the CNS. However, over the last decade it has been concluded that the levels of soluble beta-amyloid (Aβ) correlate to cognitive performance while plaques often do not. The soluble Aβ accumulate intracellularly and disturb the synaptic function. Interestingly, the levels of intracellular Aβ depend on neuronal activity. Previous studies have shown that decreased neuronal activity cause increased intracellular levels of Aβ and cognitive decline. Stress steroids produced in the brain, e.g. allopregnanolone, enhance the activity of the GABAergic system, i.e. the main inhibitory system of the brain. Consequently, allopregnanolone affects neuronal activity. Therefore, it is possible that elevated levels of allopregnanolone (due to e.g. stress) cause increased intracellular levels of Aβ. This could be a mechanism behind stress-induced AD. The purpose of this thesis was to investigate if elevation of allopregnanolone is a possible link in the mechanism behind stress-induced AD by investigating the effects of chronically elevated levels of allopregnanolone in transgenic mouse models for AD.Methods Swe/PS1 and Swe/Arc mice (transgenic models for AD) were treated chronically with elevated allopregnanolone levels, comparable to those at mild stress. After an interval of no treatment, the mice were tested for learning and memory performance in the Morris water maze. The brain tissue of the mice was then analyzed for disease markers, i.e. soluble and insoluble Aβ40 and Aβ42 using enzyme-linked immunosorbent assay, and amyloid plaques using immunohistochemistry and Congo red staining technique. The brain tissue was also analyzed for a marker of synaptic function, i.e. synaptophysin.Results Chronic treatment of allopregnanolone caused impaired learning performance in both the Swe/PS1 and the Swe/Arc mouse models. The Swe/PS1 mice had increased levels of soluble Aβ in both hippocampus and cortex. Interestingly, the levels of soluble Aβ were unchanged in the Swe/Arc mice. Three months of allopregnanolone treatment in the Swe/PS1 mouse model caused decreased plaque size, predominantly in hippocampus. It may be concluded that chronic allopregnanolone elevation caused smaller but more abundant congophilic plaques as both total plaque area and number of plaques were increased in mice with poor learning ability. Additional spots for accumulation of Aβ, predominantly the more toxic Aβ42, and thus additional starting points for plaque production could be a part of the mechanism behind stress-induced Alzheimer’s disease.Conclusions The conclusion of this thesis is that chronic elevation of allopregnanolon accelerated the development of Alzheimer’s disease in the Swe/PS1 and the Swe/Arc transgenic mouse models. Allopregnanolone may be an important link in the mechanism behind stress-induced AD. However, further studies are required to grasp the extent of its pathological influence.
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| 8. |
- Björ, Ove, 1967-
(författare)
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Strategies for assessing health risks from two occupational cohorts within the domain of northern Sweden
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Studies based on a cohort design requires access to both subject-specific and period-specific information. In order to conduct an occupational cohort study, access to exposure information and the possibility and permission to link information on outcomes from other registers are generally necessary. The analysis phase is also aggravated by its added complexity because of the longitudinal dimension of the cohort’s data.This thesis aims at increasing the knowledge on hazards from work on fatalities and cancer within the domain of cohort studies on miners and metal refiners and to study the complexity of the analysis by discussing and suggesting analytical strategies.Methods: The study population for this thesis consisted of a cohort of 2264 blue-collar aluminium smelter workers (paper I) and a cohort of 13000 blue-collar iron-ore miners (papers II-IV), both followed for over 50 years. The outcomes were collected from the Swedish Cause of Death Register and the Swedish Cancer Register. The primary methods of analysis were either Standardized Morbidity Ratios (SMR) or internal comparisons based on Cox or Poisson regression modeling. In paper IV, a g-estimation based on an accelerated failure-time model was performed to estimate the survival ratio.Results: The results from paper I suggested that working as a blue-collar worker metal refiner was associated with increased rates of incidental lung cancer. Elevated rates among short term workers were observed for several outcomes. Paper I also showed that the choice of reference population when calculating SMR could influence the conclusions of the results. In paper II, several outcomes were elevated among the miners compared to the reference population from northern Sweden. However, no outcome except lung cancer was associated with cumulative employment time. The most recurrent pattern of the results was the negative association between cumulative employment time underground and several outcomes. The results from paper III showed that cumulative employment time working outdoors was associated with increased rates of cerebrovascular disease mortality. However, employment with heavy physical workloads did not explain the previously observed decreasing rates in the selected groups of outcomes. The adjustment for the healthy worker survivor effect by g-estimation in paper IV suggested that exposure from respirable dust was associated with elevated mortality risks that could not be observed with standard analytical methods.Conclusion: Our studies found several rates from the cohorts that were elevated compared to external refererence populations but also that long term employments generally were associated with decreasing rates. Furthermore, incidental lung cancer rates was found elevated for the metal refiners. Among the miners, mortality rates of cerebrovascular diseases depended on if work was performed outdoor (higher rates) or underground (lower rates). Methodologically, this thesis has discussed different analytical strategies for handling confounding in occupational cohort studies. Paper IV showed that the healthy worker survivor effect could be adjusted for by performing g-estimation.
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| 9. |
- Blomqvist, Sven
(författare)
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Postural balance, physical activity and capacity among young people with intellectual disability
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of this thesis was to investigate postural balance, physical activity, physical capacity and their associations in young people (16-20 years) with intellectual disability (ID), mild to moderate. The aim was also to study the reliability and concurrent validity of postural balance tests.To evaluate postural balance, one assessor used five common postural balance tests and one new test. The tests were performed twice for 89 young people with ID (one to twelve days apart). Intraclass correlation coefficients greater than 0.80 were achieved for four of the common balance tests: Extended Timed Up and Go Test (ETUGT), Modified Forward Reach Test (MFRT), One-Leg Stance Test (OLS), and a Force Platform Test (FPT). The smallest real difference ranged from 12% to 40%; less than 20% is considered to be low. For the six balance tests, the concurrent validity varied between none to low.Falls are more common for young people with ID compared to young people without ID. One reason could be impaired postural balance. The postural balance for young people with ID has not been thoroughly investigated. Therefore, five balance tests and three muscle strength tests were used to compare young people with ID with an age-matched control group without ID (n=255). The young people with ID had significantly lower scores on most of the postural balance tests and muscle strength tests of the trunk and lower limbs. Muscle strength, height, and body mass index had no strong association with postural balance. The results also illustrated that young people with ID did not rely more on vision for their balance ability compared to peers without ID.It seems that postural balance is impaired for young people with ID when evaluated with common tests. An everyday situation is to react to unexpected balance disturbances to avoid falls by using different postural responses. Since young people with ID seem to fall more often than peers without ID, it is valuable to investigate if those postural responses are different between the groups. Therefore, young people with and without ID (n=99) were exposed to six backward surface translations and several postural muscle responses were evaluated: muscle synergies and strategies, muscle onset latency, time-to-peak amplitude, and adaptation. The responses of the investigated muscles – the gastrocnemius, the biceps femoris, and the erector spinae L4 level – were measured using electromyography. The results showed that there were no differences between the two groups with respect to synergies or strategies, muscle onset latency, and time-to-peak amplitude. An overall pattern was seen, that young people with ID adapted their muscle response slower in all three muscles than peers without ID, but this pattern was not statistically significant.Studies have shown that people with ID have impaired postural balance, a lower level of physical activity, and lower aerobic capacity compared to people without ID. The association is however not investigated. Therefore, postural balance (postural sway indirectly measured with the subjects standing on a force platform), physical activity (measured with a pedometer), and aerobic capacity (measured with a sub-maximal ergometer cycle test) were used to assess young people with and without ID (n=106). To investigate the subjects’ view of their own health, the subjects completed an adapted questionnaire that addressed their perceived health. The analysis showed no significant associations between postural balance, level of physical activity, and aerobic capacity. The subjects in the ID group, both men and women, had significantly lower aerobic capacity compared to subjects without ID. The answers from the health questionnaire did not correspond to the measured outcomes from the physical tests for young people with ID.In conclusion, ETUGT and MFRT can be used to evaluate change in postural balance over time in young people with mild to moderate ID. The low concurrent validity suggests that the postural balance tests probably challenge various subsystems. Young people with ID have impaired postural balance and perform lower on muscle strength tests than age-matched controls. Postural muscle responses after external perturbations seem to be similar for young people with and without ID, but the ability to adapt muscle responses after repeated perturbations appears to be slower for young people with ID. The studies in the thesis also indicate that young people with ID have reduced level of physical activity and lower aerobic capacity. The lack of association between the different physical functions indicates that they should be evaluated and exercised separately. Young persons with ID might have more difficulty realising the health advantage of being physically active, as they do not seem to make this connection. Because of this, it is important that parents/guardians, school staff, physiotherapists, and others encourage them to participate in physical activity.
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| 10. |
- Boman, Jens, 1957-
(författare)
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Prevention of Chlamydia trachomatis infections
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Urogenital chlamydia infection, caused by the bacterium Chlamydia trachomatis (CT), is the most common sexually transmitted bacterial infection in Sweden. In 2008 it was estimated by WHO that there were 105.7 million new cases of CT worldwide, an increase by 4.2 million cases (4.1%) compared to 2005. If untreated, CT infections can progress to serious reproductive health problems, especially in women. These complications include subfertility/infertility, ectopic pregnancy and chronic pain. The CT infection is often asymptomatic and reliable diagnostic methods and contact tracing are important tools for identifying infected individuals. CT infection is classified in the Swedish Communicable Diseases Act as a serious disease; consequently, written reporting and contact tracing are compulsory. Previous or ongoing CT infection is not uncommon in infertile couples, especially in women with tubal factor infertility (TFI). We have tested 244 infertile couples for CT antibodies, and CT IgG positive couples were tested for CT DNA in urine. The prevalence of CT antibodies was higher in infertile men and women, and ongoing CT infection was common. Our results support a role of CT in infertility and underscore the importance of prevention of CT infection. Contact tracing was studied during using questionnaires. A total of 544 questionnaires was sent to tracers in a Swedish county and 534 (98%) were completed. Centralized contact tracing performed by experienced tracers is effective; on average 65% of sexual contacts found by contact tracing are CT-infected. Our data show that it is worthwhile to extend the tracing period beyond 6 months as 30% of reported sexual contacts between months 7-12 were CT-infected. Contact tracing may be performed face-to-face at the clinic or by telephone. Because of the severe consequences of CT infection there is a need for useful methods for both primary and secondary prevention of CT and other sexually transmitted infections (STIs). An important sub-population for CT/STI-prevention is the “core group”, i.e. a subpopulation with high incidence of STIs combined with risky sexual behaviours. This subpopulation contributes particularly to the spread of STIs in the population. Therefore, we have developed and evaluated a brief standardised but flexible manual-based single-session intervention based on motivational interviewing (MI) for the reduction of high risk sexual behaviour. Women (n=105) and men (n=119) at high risk of contracting CT infection were randomly eighter offered brief MI counselling or standard care. Our findings support the effectiveness of brief MI-based counselling in reducing high-risk sexual behaviour and incident CT infection in women (p<0.01) but not in men. Our results suggest that gender aspects need to be considered and that men and women should be treated differently for achieving maximal risk-reduction. Whereas it might be sufficient to include information and motivation when performing risk-reducing counselling on women, counsellors may also add other components, such as behavioural skills and booster sessions, when counselling is performed on men.
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