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Work-related repetitive strain injury (RSI), one of the work-related musculoskeletal disorders, is the most commonly reported occupational illness, yet the pathophysiological mechanisms are not yet clear. Using our unique RSI animal model, pathophysiological tissue responses can be examined simultaneously with behavioral responses that serve as indicators of sensorimotor function. Studies in humans and with this animal model have shown that prolonged performance of repetitive tasks leads to declines in grip strength and increased of serum pro-inflammatory cytokines, both valuable biomarkers of underlying tissue injuries. Identification of biomarkers would help to elucidate the time course of the inflammatory stage of these disorders and disease progression. Sickness responses/behaviors, normal responses and behaviors occurring as a consequence of infection or illness, are responsible for re-organizing perceptions and actions to enable individuals to respond appropriately to the infection, injury and other illnesses. These behaviors can include malaise, fatigue, increased irritability and social withdrawal, behaviors that can be beneficial when ill for avoiding others and enhancing wellness. However, sickness behaviors can also include depression, sleep disorders and an enhanced perception of illness. Although recent studies have shown that circulating pro-inflammatory cytokines in serum may trigger sickness behaviors, only a few studies have examined if there is an association between work-related musculoskeletal disorders and subsets of sickness behavior; no one to date has elucidated any plausible biological cause of this association. Also, the combined effects of both aging and performance of repetitive tasks needs more evaluation since several epidemiological studies have shown a relationship between advancing age and susceptibility to musculoskeletal disorders. Therefore, using female Sprague-Dawley rats, the aims of this dissertation project are to: 1) To determine if a systemic inflammatory response is maintained long-term in rats exposed to a moderate demand lever-pulling task with high repetition, low force (HRLF) requirements; if aging enhances this systemic inflammatory response and if this response correlates with functional motor declines; 2) To determine if performance of repetitive upper extremity tasks leads to the development of sickness behaviors (weight loss, decreased social interaction and increased aggression); 3) To determine if a relationship between repetitive upper extremity tasks lead to the development of dose- and age-dependent sickness behaviors, and, to determine if increased serum or brain inflammatory cytokines are plausible mechanisms for the induction of sickness behaviors in this model; and, lastly, 4) To determine if prophylactic or secondary systemic treatments with anti-inflammatory drugs (anti--tumor necrosis factor alpha or ibuprofen) reduces sickness behaviors in rats performing a high demand high repetition high force (HRHF) reaching and handle pulling task. This finding would be in further support of an underlying task-induced inflammatory mechanism contributing to these sickness behaviors. In the first study, the relationship between serum and grip strength was examined in aged and young adult rats performing a HRLF task. Serum levels of interleukin 1-alpha (IL-1α), interferon-gamma (IFNγ) and IL-6 were higher in aged rats in general, compared to young adult rats. Each increased more in aged trained-only and 12-week HRLF rats than in young adult trained-only and 12-week HRLF rats. Serum IL-6 showed the greatest increases, with the highest levels observed in aged 12-week HRLF rats. Grip strength declined with task performance in both age groups; however, this decline correlated negatively and only moderately with serum IL-6 levels in aged rats. Thus, aging enhanced a serum cytokine response in general, a response that was even greater with repetitive task performance. Grip strength was adversely affected by task performance in both age groups, but was apparently influenced by factors other than serum cytokine levels in young rats. In the second study, the relationship between sickness behaviors (weight loss, duration of social interaction and aggression towards novel juvenile rats), serum cytokines and brain cytokines were examined in aged and young adult rats that trained to one of two task levels before performing a HRLF task. Decreased duration of social interaction and increased aggression was greater in both young adult and aged rats that trained for 10 min/day for 4-5 weeks to learn a high force (TRHF) task, compared to young adult and aged rats that learned a low force (TRLF) task. TRHF and TRLF rats of both age groups then performed a HRLF task for 6 to 24 weeks, rats termed TRHF-HRLF and TRLF-HRLF, respectively. Declines in social interaction resolved by week 3 in young adult TRHF-HRLF rats, but were still evident in 6-week aged TRHF-HRLF rats (the final endpoint for TRHF-HRLF rats). Significant increases in aggression were observed only in TRHF-HRLF rats, in both age groups. Declines in social interaction were also observed in aged rats performing a TRLF-HRLF task through week 9, but not in young adult TRLF-HRLF rats, even those performing the HRLF task for 24 weeks. These behaviors correlated moderately with increased serum IL-6 observed in the aged task rats (both TRHF-HRLF and TRLF-HRLF) and young adult TRHF-HRLF rats, although serum TNFalpha and IL-1beta also increased with task performance. Increased IL-6 and IL-6 receptor was detected immunohistochemically in brains of aged TRHF-HRLF rats, specifically in ependymal and endothelial cells, as well as glial cells and neurons of the anterior cingulate cortex and paraventricular nucleus. Thus, training to high force, even for a short time period, induced increased sickness behaviors. Aging contributed to increased sickness behaviors in repetitive task rats, and to increased expression of IL6 and IL-6 receptor in several brain regions. In the third study, the relationships between sickness behaviors (duration of social interaction and aggression towards novel juvenile rats), serum cytokines and brain cytokines were examined in young adult rats performing a high repetition high force (HRHF) task with or without anti-inflammatory medications. Rats that trained to high force (TRHF) had decreased duration of social interaction and increased aggression; these behaviors were prevented by prophylactic anti-TNFalpha or ibuprofen treatment. Untreated TRHF rats that went on to perform a HRHF task showed decreased social interaction and increased aggression through week 12; these behaviors were attenuated by secondary anti-TNFalpha and ibuprofen treatments. Untreated HRHF rats had increased serum GroKC, IFN-gamma, IL-1beta, MIP2, MIP3a and TNFalpha. These increases were attenuated after two weeks of anti-TNFalpha treatment in HRHF weeks 5-6, and after 8 weeks of ibuprofen (in HRHF weeks 5-12). The sickness behaviors correlated moderately with increased serum Gro-KC, MIP2 and TNFalpha, and were concomitant with increased IL-1beta immunoexpression in ependymal and endothelial cells in brains of untreated TRHF and HRHF rats. Both treatments reduced the increased brain IL-1beta expression. Thus, sickness behaviors induced by overuse are attenuated by anti-inflammatory interventions that reduce task-induced increases in systemic and brain inflammatory cytokines. In conclusion, both aging and task performance increased serum inflammatory cytokine responses, the latter in an exposure-dependent manner, with a greater serum cytokine response with performance of high force tasks than low force tasks. While grip strength was adversely affected by task performance in both young and aged rats, it was influenced by factors other than serum cytokine levels. In contrast, decreased duration of social interaction and increased incidence of aggression were influenced by task-induced increases in serum and brain inflammatory cytokines, responses attenuated to baseline levels with systemic anti-inflammatory treatments. Sickness behaviors were also dose- and age-dependent, with higher incidence with performance of high force tasks than with low force tasks, and higher incidence in aged rats. We postulate that the higher incidence in aged rats is due to aged-induced brain "inflamm-aging", as they also had increased immunoexpression of IL6 and IL6 receptor in blood brain barrier cells and in glial and neurons of the hypothalamic pituitary axis. / Physical Therapy

No / The aim of the present study was to investigate an opioid receptor involvement in the adaptation response to motion sickness in Suncus murinus. Different groups of animals were treated intraperitoneally with either saline, morphine (0.1 and 1.0 mg/kg), naloxone (1.0, 10.0 and 5.0 mg/kg) or a combination of naloxone plus morphine in the absence or 30 min prior to a horizontal motion stimulus of I Hz and 40 mm amplitude. For the study of adaptation, different groups received saline on the first trial, and in subsequent trials (every 2 days) they received either saline, naloxone (1.0 and 10.0 mg/kg, ip) or morphine (0.1 mg/kg, ip) 30 min prior to the motion stimulus. Pretreatment with morphine caused a dose-related reduction in emesis induced by a single challenge to a motion stimulus. Pretreatment with naloxone alone did not induce emesis in its own right nor did it modify emesis induced by a single challenge to a motion stimulus. However, pretreatment with naloxone (5.0 mg/kg, ip) revealed an emetic response to morphine (P<.001) (1.0 mg/kg, ip) and antagonised the reduction of motion sickness induced by morphine. In animals that received saline or naloxone (1.0 mg/kg), a motion stimulus inducing emesis decreased the responsiveness of animals to a second and subsequent motion stimulus challenge when applied every 2 days for 11 trials. However, the animals receiving naloxone 10.0 mg/kg prior to the second and subsequent challenges showed no significant reduction in the intensity of emesis compared to the first trial. The data are revealing of an emetic potential of morphine when administered in the presence of a naloxone pretreatment. The administration of naloxone is also revealing of an additional inhibitory opioid system whose activation by endogenous opioid(s) may play a role in the adaptation to motion sickness on repeated challenge in S. murinus.

The purpose of this thesis has been to analyse seven major factors that tend to influence the rate of early retirement in Sweden. The scope of data was gathered for every municipality in Sweden. Economic theories of labour supply, Moral Hazard, Adverse Selection and the Insurance Model were used to analyse the empirical results. In the analysis, earlier studies of the rate of sickness absence were important and used as a framework in choosing the explanatory variables for the econometric model. The analysed variables were; average income, average sickness days, educational level, foreign born, public sector employment, unemployment and the share of women in the population. As a consequence of the rift that occurred in 2003, when the average sickness days decreased and disbursed early retirements simultaneously increased, the relationship between these two variables was given special attention. The empirical findings confirmed our conjectures and were consistent with earlier research. Average income and the level of education were negatively related to the rate of early retirement. Moreover foreign born, average sickness days and unemployment showed a positive relation to early retirement. The relationship between average sickness days and early retirement had statistically changed and decreased between the years. A possibility is that other factors, such as changed social norms and increased stress in society (which are difficult to measure in a statistical and economical sense) might have become more relevant in explaining the rate of early retirement. / Syftet med denna uppsats har varit att analysera sju viktiga faktorer som tenderar att påverka graden av förtidspensionering i Sverige. Data omfånget insamlades för alla kommuner i Sverige. Ekonomiska teorier om arbetsutbud, Moral Hazard, Adverse Selection och Insurance Model användes för att analysera de empiriska resultaten. I analysen var tidigare studier utav graden av sjukfrånvaro viktig och användes som ramverk i valet av de förklarande variablerna till den ekonometriska modellen. De analyserade variablerna var; medelinkomst, genom-snittliga sjukdagar, utbildningsnivå, utlandsfödda, offentligt anställda, arbetslöshet och andelen kvinnor i befolkningen. Som en konsekvens utav den klyfta som uppstod 2003, när de genomsnittliga sjukdagarna minskade och utbetalda förtidspensioner samtidigt ökade, gavs sambandet mellan dessa två variabler speciell uppmärksamhet. De empiriska iakttagelserna bekräftade våra förväntningar och stämde överens med tidigare forskning. Medelinkomst och utbildningsnivå var negativt relaterade till graden av förtidspensionering. Dessutom var utlandsfödd, genomsnittliga sjukdagar och arbetslöshet positivt relaterade till förtidspensionering. Relationen mellan de genomsnittliga sjukdagarna och graden av förtidspensionering hade statistiskt sätt ändrats genom att ha minskat mellan åren. En tänkbar förklaring till detta skulle kunna vara att andra faktorer, såsom skiftande sociala normer och en ökande stress i samhället (vilka är svåra att mäta statistiskt och ekonomiskt) kan ha blivit mer relevanta i att förklara graden av förtidspensionering.

Which factors best explain the regional variation in sick-listing and early retirement? Data from the Swedish Social Insurance Agency is fitted against variables describing different regional characteristics that have been linked to sickness insurance consumption in the literature. Results, in line with earlier empirical investigation, suggest that particularly the employment rate, the populations‟ age, and its wealth are strong determinants of regional insurance usage. Two further factors, though less discussed in the literature, appear to have some relevance as well: A high share of large workplaces is found to predict higher rates of early retirement, while a large share of foreign-born predict lower sick-listing rates. Both effects have been found before, though the first one perhaps not in Swedish cross section analysis and the latter does not appear to be well understood in the literature. A tentative explanation for it is given here.

<p>Which factors best explain the regional variation in sick-listing and early retirement? Data from the Swedish Social Insurance Agency is fitted against variables describing different regional characteristics that have been linked to sickness insurance consumption in the literature. Results, in line with earlier empirical investigation, suggest that particularly the employment rate, the populations‟ age, and its wealth are strong determinants of regional insurance usage. Two further factors, though less discussed in the literature, appear to have some relevance as well: A high share of large workplaces is found to predict higher rates of early retirement, while a large share of foreign-born predict lower sick-listing rates. Both effects have been found before, though the first one perhaps not in Swedish cross section analysis and the latter does not appear to be well understood in the literature. A tentative explanation for it is given here.</p>

<p>The purpose of this thesis has been to analyse seven major factors that tend to influence the rate of early retirement in Sweden. The scope of data was gathered for every municipality in Sweden. Economic theories of labour supply, Moral Hazard, Adverse Selection and the Insurance Model were used to analyse the empirical results. In the analysis, earlier studies of the rate of sickness absence were important and used as a framework in choosing the explanatory variables for the econometric model. The analysed variables were; average income, average sickness days, educational level, foreign born, public sector employment, unemployment and the share of women in the population. As a consequence of the rift that occurred in 2003, when the average sickness days decreased and disbursed early retirements simultaneously increased, the relationship between these two variables was given special attention. The empirical findings confirmed our conjectures and were consistent with earlier research. Average income and the level of education were negatively related to the rate of early retirement. Moreover foreign born, average sickness days and unemployment showed a positive relation to early retirement. The relationship between average sickness days and early retirement had statistically changed and decreased between the years. A possibility is that other factors, such as changed social norms and increased stress in society (which are difficult to measure in a statistical and economical sense) might have become more relevant in explaining the rate of early retirement.</p> / <p>Syftet med denna uppsats har varit att analysera sju viktiga faktorer som tenderar att påverka graden av förtidspensionering i Sverige. Data omfånget insamlades för alla kommuner i Sverige. Ekonomiska teorier om arbetsutbud, Moral Hazard, Adverse Selection och Insurance Model användes för att analysera de empiriska resultaten. I analysen var tidigare studier utav graden av sjukfrånvaro viktig och användes som ramverk i valet av de förklarande variablerna till den ekonometriska modellen. De analyserade variablerna var; medelinkomst, genom-snittliga sjukdagar, utbildningsnivå, utlandsfödda, offentligt anställda, arbetslöshet och andelen kvinnor i befolkningen. Som en konsekvens utav den klyfta som uppstod 2003, när de genomsnittliga sjukdagarna minskade och utbetalda förtidspensioner samtidigt ökade, gavs sambandet mellan dessa två variabler speciell uppmärksamhet. De empiriska iakttagelserna bekräftade våra förväntningar och stämde överens med tidigare forskning. Medelinkomst och utbildningsnivå var negativt relaterade till graden av förtidspensionering. Dessutom var utlandsfödd, genomsnittliga sjukdagar och arbetslöshet positivt relaterade till förtidspensionering. Relationen mellan de genomsnittliga sjukdagarna och graden av förtidspensionering hade statistiskt sätt ändrats genom att ha minskat mellan åren. En tänkbar förklaring till detta skulle kunna vara att andra faktorer, såsom skiftande sociala normer och en ökande stress i samhället (vilka är svåra att mäta statistiskt och ekonomiskt) kan ha blivit mer relevanta i att förklara graden av förtidspensionering.</p>

African horse sickness (AHS) is a viral disease with high mortality rates, vectored by the Culicoides midge and affecting members of the Equidae family. AHS is endemic to South Africa, and, as a result, affects export and international competitiveness in equine trade, and impacts significantly on the South African racehorse and performance horse industries. AHS also has devastating consequences for rural and subsistence equine ownership. The protocol developed in this dissertation has the potential to serotype and confirm the AHS virus within a few hours at significantly less cost than current methods. It will ease the financial and time constraints of studying an outbreak in real time and has the potential to solve many of the unknown factors surrounding AHS, particularly and most importantly, the role that each serotype plays in outbreaks and the form of the disease contracted by horses. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

This thesis studies how sick leave legitimacy is managed in interaction and develops an empirically driven conceptualization of ‘legitimacy work’. The thesis applies an ethnomethodological framework that draws on conversation analysis, discursive psychology, and membership categorization analysis. Naturally occurring interaction is examined in two settings: (1) multi-party meetings at the Swedish Social Insurance Agency, in which participants assess and discuss the ‘status’ of the sick leave and plan for work rehabilitation; (2) peer-based online text-in-interaction in a Swedish forum thread that gathers people on sick leave. The thesis shows how mental states, activities and alternative categories function as resources for legitimacy work. However, such invocations are no straight-forward matter, but impose additional contingencies. It is thus crucial how they are invoked. By detailed analyses of the interaction, with attention to aspects such as lexicality and delivery, the thesis identifies a range of discursive features that manage sick leave legitimacy. Deployed resources are also subtle enough to be deniable as legitimacy work, that is, they also manage the risk of an utterance being seen as invested or biased. While legitimate sick leave is a core concern for Swedish policy-making, administration, and public debate on sick leave, previous research has for the most part been explanatory in orientation, minding legitimacy rather than studying it in its own right. By providing detailed knowledge about the legitimacy work that people on long-term sick leave do as part of both institutional and mundane encounters, the thesis contributes not only new empirical knowledge, but a new kind of empirical knowledge, shedding light on how the complexities of sick leave play out in real-life situations. Traditional sociological approaches have to a significant extent treated legitimacy as an entity with beginnings and ends that in more or less direct ways relate to external norms and cognitive states, or that focus on institutions, authority or government. By contrast, the herein emerging concept ‘legitimacy work’ understands legitimacy as a locally contingent practicality – a collaborative categorially oriented accomplishment that is integral to the interactional situation.