Type I Diabetes Mellitus (T1DM) is a major health problem and a burden for affected young individuals, as well as for society. It is among the most prevalent paediatric disorders, affecting an estimated 1.7 per 100 children and adolescents. Given the complexity of diabetes treatment regimens, it is not surprising that children, adolescents, and their families often have difficulty adhering to these regimens. Studies have found that the overall adherence rate among children and adolescents with diabetes is about 50%. It has also been found that adherence to T1DM often tends to decrease when the adolescent begins to assume most of the responsibility for managing the disease and the parents‟ role starts to decline. However, literature indicates that adolescent patients‟ adherence is poor and an important strategy to improving their metabolic control is to increase self-care. The most common age of onset for T1DM is between 10-14 years. The adolescent population is highly neglected in current research on diabetes, because the focus tends to favour children and not adolescents. It is widely recognised that glycaemic control in adolescents is complex, challenging and dependent on interconnected relationships between numerous inputs at individual, family, community and health service levels. Optimal care of adolescents with diabetes has not been subjected to rigorous scientific studies, and research results related to optimal glycaemic control are conflicting. Development and continuous evaluation of best practices pertaining to diabetes mellitus remains one of the major objectives of diabetes care, possibly allowing a delay in and/or prevention of later complications. Research indicates that adolescence is the one age group where there has been no discernible improvement in health over the last 20 years. A great number of research studies on the subject of diabetes are done globally, but less literature, especially in the South African context, can be found that focuses on and explain the experiences of adolescents with T1DM with regard to their treatment adherence. This qualitative study explored the experiences of adolescents with T1DM. A purposive sample (n=7) of young adolescents between the ages of 13 and 15 willingly participated in the research study to explore and describe their experiences with managing their treatment regimen. In-depth interviews were conducted to collect rich descriptive data, followed by participants‟ verbal reflections once a week for the duration of a month. After the in-depth interviews and weekly reflections, the researcher held a focus group interview with all the participants. Transcribed data were analysed by means of thematic analysis from which themes and subthemes were derived. The participants expressed both positive and negative emotions associated with their diabetes; they experienced a lack of understanding by significant others because of a lack of knowledge, interest or support regarding their diabetes; they mentioned that they continually need age-appropriate support and parental involvement, even though they manage diabetes through their own processes; and lastly, participants struggled with a fear of friends‟ and peers‟ perceptions. From the findings it is clear that in order to cope, the adolescents need not only medical treatment and education about diabetes (T1DM), but emotional support, supervision and repeated reinforcement to achieve effective self-management. The basic suggestion is that diabetes care for children and young people should include routine assessment of the psychological and social pressures on the adolescent and the family so that strategies can be put in place to give support and education as needed and as appropriate. The researcher also recommends that school personnel must be educated about diabetes so that they can understand the changing medical and psychosocial needs of the adolescent and can help him/her to participate fully in all the available work, sport, and leisure activities. Models of legislation and training programmes for school staff specifically addressing the needs of children with diabetes in school have been developed in a number of countries such as Greece, Germany, Italy, Poland, Spain, Sweden, the UK and the USA. These programmes should be considered as an example to other countries. These best practices can serve as a foundation for national improvement. / MA (Psychology), North-West University, Potchefstroom Campus, 2015

Type I Diabetes Mellitus (T1DM) is a major health problem and a burden for affected young individuals, as well as for society. It is among the most prevalent paediatric disorders, affecting an estimated 1.7 per 100 children and adolescents. Given the complexity of diabetes treatment regimens, it is not surprising that children, adolescents, and their families often have difficulty adhering to these regimens. Studies have found that the overall adherence rate among children and adolescents with diabetes is about 50%. It has also been found that adherence to T1DM often tends to decrease when the adolescent begins to assume most of the responsibility for managing the disease and the parents‟ role starts to decline. However, literature indicates that adolescent patients‟ adherence is poor and an important strategy to improving their metabolic control is to increase self-care. The most common age of onset for T1DM is between 10-14 years. The adolescent population is highly neglected in current research on diabetes, because the focus tends to favour children and not adolescents. It is widely recognised that glycaemic control in adolescents is complex, challenging and dependent on interconnected relationships between numerous inputs at individual, family, community and health service levels. Optimal care of adolescents with diabetes has not been subjected to rigorous scientific studies, and research results related to optimal glycaemic control are conflicting. Development and continuous evaluation of best practices pertaining to diabetes mellitus remains one of the major objectives of diabetes care, possibly allowing a delay in and/or prevention of later complications. Research indicates that adolescence is the one age group where there has been no discernible improvement in health over the last 20 years. A great number of research studies on the subject of diabetes are done globally, but less literature, especially in the South African context, can be found that focuses on and explain the experiences of adolescents with T1DM with regard to their treatment adherence. This qualitative study explored the experiences of adolescents with T1DM. A purposive sample (n=7) of young adolescents between the ages of 13 and 15 willingly participated in the research study to explore and describe their experiences with managing their treatment regimen. In-depth interviews were conducted to collect rich descriptive data, followed by participants‟ verbal reflections once a week for the duration of a month. After the in-depth interviews and weekly reflections, the researcher held a focus group interview with all the participants. Transcribed data were analysed by means of thematic analysis from which themes and subthemes were derived. The participants expressed both positive and negative emotions associated with their diabetes; they experienced a lack of understanding by significant others because of a lack of knowledge, interest or support regarding their diabetes; they mentioned that they continually need age-appropriate support and parental involvement, even though they manage diabetes through their own processes; and lastly, participants struggled with a fear of friends‟ and peers‟ perceptions. From the findings it is clear that in order to cope, the adolescents need not only medical treatment and education about diabetes (T1DM), but emotional support, supervision and repeated reinforcement to achieve effective self-management. The basic suggestion is that diabetes care for children and young people should include routine assessment of the psychological and social pressures on the adolescent and the family so that strategies can be put in place to give support and education as needed and as appropriate. The researcher also recommends that school personnel must be educated about diabetes so that they can understand the changing medical and psychosocial needs of the adolescent and can help him/her to participate fully in all the available work, sport, and leisure activities. Models of legislation and training programmes for school staff specifically addressing the needs of children with diabetes in school have been developed in a number of countries such as Greece, Germany, Italy, Poland, Spain, Sweden, the UK and the USA. These programmes should be considered as an example to other countries. These best practices can serve as a foundation for national improvement. / MA (Psychology), North-West University, Potchefstroom Campus, 2015

Le diabète de Type 1 est une maladie auto-immune caractérisée par la perte de production d'insuline par les îlots [béta] du pancréas. Les causes menant à la destruction de ces îlots par les cellules T autoréactives sont méconnues. Certains événements tels qu'une infection virale ou des facteurs environnementaux peuvent déclencher cette auto-immunité. Chez le rat BB-DP qui développe un diabète de type 1 semblable à l'homme, une mutation qui affecte les cellules T a été découverte. La mutation nommée lyp amène une perte de survie des cellules T dans la périphérie malgré tous les facteurs de survie des cellules T présents chez l'animal. Cette mutation située sur le chromosome 4 affecte un gène de la famille GIMAP, plus particulièrement la protéine GIMAP5 qui se retrouve tronquée et non fonctionnelle. Des résultats du laboratoire ont démontré une implication de GIMAP5 dans la voie du calcium. La manière par laquelle GIMAP5 joue son rôle dans la survie des lymphocytes T n'est pas connue. Afin de comprendre ces fonctions, nous voulons identifier la localisation cellulaire de GIMAP5 ainsi que ses partenaires d'interaction. Les lignées cellulaires transfectées avec le gène de GIMAP5 étiqueté ont été marquées en fluorescence à l'aide de marqueurs d'organelles et examinées en microscopie confocale afin de déterminer la localisation de GIMAP5. Une étude de double-hybride combinée avec des marquages fluorescents à l'aide d'anticorps fluorescents dirigés contre ces protéines et l'utilisation de la microscopie confocale permettent de vérifier les partenaires d'interaction de GIMAP5. Les cellules T de rats gimap5[indice supérieur lyp/lyp] et sauvages ont été utilisées afin de faire des marquages au Rhod-2 (calcium mitochondrial) et de vérifier l'effet de la mutation sur la capacité des mitochondries à absorber le calcium. Une localisation de GIMAP5 au niveau du RE a été identifiée dans les cellules HEK 293T surexprimant GIMAP5, mais n'as [i.e. n'a] pu être vu chez les lignées de cellules T Jurkats. Les résultats de l'étude de double-hybride ont donné des partenaires d'interaction de faible affinité (avec une cote de D). Les essais de microscopie confocale n'ont pu démontrer cette interaction. Finalement, les mitochondries des cellules T de rats gimap5[indice supérieur lyp/lyp] ont une vitesse d'incorporation du calcium plus lente et un retour à la normale plus lent que les mitochondries des cellules T de rats sauvages. Chez le rat, GIMAP5 semble jouer un rôle au niveau de l'homéostasie du calcium et de l'intégrité des mitochondries, puisque la mutation gimap5[indice supérieur lyp/lyp] apporte une baisse du potentiel membranaire des mitochondries et une baisse de l'accumulation du calcium par ces dernières.Le mécanisme par lequel GIMAP5 régule l'homéostasie du calcium reste encore à élucider.

Intra-adipose cortisol is derived from the systemic circulation via the hypothalamic-pituitaryadrenal axis (HPAA) and generated locally through conversion of inactive cortisone to cortisol by the intra-cellular enzyme 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1). This thesis addresses the relative contributions of the HPAA and adipose tissue 11βHSD1 to the adipose tissue glucocorticoid pool and describes development and validation of a novel stable isotope tracer, 1,2 [2H]2-cortisone (d2-cortisone), to measure 11βHSD1- dehydrogenase activity in adipose tissue and skeletal muscle in vivo. In otherwise healthy females (n=6) undergoing hysterectomy for a benign indication, an intravenous infusion of d4-cortisol was administered and subcutaneous and omental adipose tissue biopsies were obtained along with concomitant peripheral venous blood, to measure the rate of exchange of cortisol between plasma and adipose tissue for comparison with rates of intra-cellular cortisol generation by 11βHSD1. Cortisol concentrations and enrichment with d4-cortisol were lower in adipose tissue than in plasma. The rate of accumulation of d4-cortisol in adipose tissue depots was ~0.5nmol/kg/h despite the infusion contributing 1.9μmol/h d4-cortisol into the circulation, and the proportion of the intra-adipose cortisol pool replaced each hour was ~10%. The contribution of 11βHSD1 to this turnover could not be quantified since very little substrate d3-cortisone accumulated in adipose during infusion. Method development for d2-cortisone included optimising LC-MS/MS conditions, confirming that d2-cortisone was a substrate for human 11βHSD1 and that no significant primary isotope effect existed. The pharmacokinetics of d2-cortisone were assessed in vivo in healthy male volunteers (n=3). The method was validated by measuring whole body cortisone production in healthy volunteers (n=3) before and after eating liquorice which resulted in a ~50% fall in cortisone production. 11βHSD1-dehydrogenase activity was measured in adipose tissue and skeletal muscle in healthy volunteers (n=6) using d2- cortisone and substantial 11β-dehydrogenase activity was present in both tissues (~1.5-fold higher 11β-dehydrogenase activity than 11β-reductase activity in adipose tissue and approximately equal 11β-reductase and 11β-dehydrogenase activity in skeletal muscle). 11βHSD1-reductase activity was also assessed using a 9,11,12,12 [2H]4-cortisol infusion (d4-cortisol). Skeletal muscle and adipose tissue displayed 11β-reductase activity. In adipose tissue this activity was of a similar magnitude to previous reports. Insulin increased whole body 11β-reductase activity, but did not switch 11βHSD1 direction in muscle or adipose tissue, indicating the predominant effect of insulin may be on hepatic 11βHSD1. Therefore, turnover of the intra-adipose tissue glucocorticoid pool is slow and it is unlikely that rapid acute fluctuations in circulating cortisol are reflected in adipose tissue, although this has not been confirmed under normal physiological conditions. Secondly, 11βHSD1 may be bidirectional in human subcutaneous adipose tissue and skeletal muscle in vivo, and insulin does not regulate the balance of activities. However, in this study blood sampling occurred from blood vessels which express 11βHSD2, and thus some of the measured dehydrogenase activity in this study may reflect endothelial 11βHSD2 activity. Together these findings further our understanding of adipose tissue cortisol physiology in health, suggesting that 11βHSD1 may play a relatively important role in modulating activation of glucocorticoid receptors in adipose tissue, and that dysregulation or inhibition of 11βHSD1 may affect cortisol inactivation as well as regeneration.

Inflammation plays a key role in the underlying pathogenesis of obesity and its associated health risks, with increased markers of inflammation evident in both liver and adipose tissue. In parallel, there is dysregulation of glucocorticoid metabolism in obesity, with increased adipose levels of the glucocorticoid-regenerating enzyme 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) and increased hepatic levels of 5α-reductase type 1 (5αR1), which catalyses the reduction of glucocorticoids. Both the mechanisms and consequences of this glucocorticoid metabolism dysregulation remain unclear, however, there is evidence that it may be related to inflammation. In vitro studies have demonstrated that pro-inflammatory markers upregulate 11βHSD1 expression in adipocytes, potentially explaining increased expression of this enzyme in obesity. Previous work has also demonstrated that the glucocorticoid metabolites produced by 5αR1 lack the metabolic effects of the parent glucocorticoid, but retain its anti-inflammatory properties, indicating that increased expression of hepatic 5αR1 may serve to dampen down inflammation in the liver. The hypotheses addressed in this thesis are that in obesity, inflammation regulates adipose glucocorticoid metabolism through 11βHSD1, and that hepatic glucocorticoid metabolism regulates the inflammatory state of the liver through 5αR1. The role of inflammation in the regulation of 11βHSD1 was assessed in vivo in mice treated with the anti-inflammatory compound sodium salicylate (salicylate). In diet-induced obese mice, salicylate downregulated 11βHSD1 expression and activity selectively in visceral adipose tissue, alongside improved glucose tolerance, reduced plasma non-esterified fatty acids, and changes in adipose lipid metabolism. 11βHSD1-deficient mice fed a high-fat diet were resistant to the insulin sensitising effects of salicylate treatment. These results indicate a novel role for 11βHSD1 down-regulation in mediating the insulin sensitising effect of anti-inflammatory treatment. The mechanisms underpinning the anti-inflammatory properties of 5α-reduced glucocorticoids were explored in vitro and in vivo. In lipopolysaccharide-stimulated murine macrophages, both 5α-reduced glucocorticoid metabolites tested, namely 5α-dihydrocorticosterone (5αDHB) and 5α-tetrahydrocorticosterone (5αTHB), suppressed tumor necrosis factor-α (TNFα) and interleukin-6 (IL-6) release, although to a lesser extent than corticosterone (B). Similar to B, both 5αDHB and 5α THB suppressed phosphorylation of intra-cellular inflammatory signalling mitogen-activated protein kinases (MAPK) proteins c-Jun N-terminal kinase (JNK) and p38, as well as increasing protein expression of MAPK phosphatase-1 (MKP-1). Treatment of phorbol ester-stimulated HEK293 kidney cells with these 5α-metabolites revealed that 5αDHB suppressed nuclear factor κB (NFκB) and activator protein-1 (AP-1) activation to a similar extent to that of B, whilst 5αTHB increased activation of these pro-inflammatory transcription factors, indicating cell-specific effects of 5αTHB. In conclusion, reduced intra-adipose glucocorticoid regeneration by 11βHSD1 mediates the insulin sensitising effects of salicylate, suggesting that altered glucocorticoid metabolism may reflect altered intra-adipose inflammation in obesity. Furthermore, these data support the concept that this enzyme provides a therapeutic target in obesity-related metabolic disorders. 5α-reduced metabolites of glucocorticoids have similar anti-inflammatory properties to the parent glucocorticoid, indicating that the elevated hepatic levels of 5α-reductase in obesity may be a protective mechanism to limit the adverse metabolic effects of glucocorticoids upon the liver, but maintain the beneficial anti-inflammatory properties. These 5α-reduced glucocorticoid metabolites may provide a potential therapeutic treatment as selective glucocorticoid receptor modulators for inflammatory conditions.

Diabetes typ 1 är en kronisk sjukdom vars incidens och prevalens ökar i Sverige. Sjukdomen debuterar vanligtvis i barndomen och medför livslång behandling. Därför krävs det att familjen lär sig att hantera och leva med sjukdomen i det vardagliga livet. Syftet med studien var att beskriva familjens erfarenheter av att leva med ett barn som har diabetes typ 1. Metoden som valdes var en litteraturöversikt. Studien bygger på 13 kvalitativa artiklar. Sökningen gjordes i databaserna CINAHL och PubMed. I resultatet framkom följande fyra teman: att familjerelationerna förändras, att leva med ökad oro och rädsla, att familjens levnadsvanor förändras samt att leva med ökat ansvar. Resultatet visade att hela familjen påverkas när ett barn i familjen insjuknar i diabetes typ 1. Inledningsvis upplever familjen en jobbig period då de måste skaffa nya rutiner för att upprätthålla barnets hälsa. När familjen fått mer erfarenhet och kunskap blir de tryggare i situationen. Trots det känner de alltid oro för barnet. Slutsatsen är att sjuksköterskan har en betydelsefull roll för hela familjen och det är viktigt att skilja på familjens och barnets erfarenheter. Det är viktigt att sjuksköterskan har kunskap om familjens erfarenheter för att möta deras behov och anpassa vården utefter det. / Type 1 diabetes is a chronic disease which incidence and prevalence is increasing in Sweden. It is most common that the disease debuts in childhood. The child with type 1 diabetes requires lifelong treatment and therefore the family has to learn how to manage the disease in everyday life. The aim of this study was to describe the family’s lived experiences when a child has type 1 diabetes. The chosen method was a literature review. The study is based on 13 qualitative articles which were found in the databases CINAHL and PubMed. The results showed following four themes: changed family relationships, increased concern and fear, changed living habits and increased responsibility. Initially the family experiences a difficult time and they need to set up new routines to maintain the child’s health. Experiences gain knowledge and leads to security over time. Although the family are always concerned about the child. Therefore the nurse has an important role for the whole family and it is important to distinguish between the family’s experiences and the child’s experiences. It is important that the nurse has the knowledge of the family’s experiences in order to understand their needs and adapt the care.

Bakgrund: Typ- 1 diabetes är en autoimmun sjukdom som behandlas med tillförsel av insulin, goda matvanor och regelbunden fysisk aktivitet. Sjukdomen drabbar ofta barn och ungdomar som beskriver en svårighet att balansera egenvården med vardagslivet. Syfte: Att belysa tonåringars och ungdomars upplevelser av att leva med typ 1- diabetes. Metod: En litteraturstudie genomfördes, 8 kvalitativa artiklar inkluderades i resultatet och analyserades genom Fribergs metod. Resultat: Fem kategorier skapades vid analys: Relationer till omgivningen, stöd respektive brist på stöd från omgivningen, förlorad autonomi, känslomässiga och fysiska reaktioner och hantering och anpassning. Konklusion: Att leva med typ-1 diabetes kan vara tufft på många sätt för tonåringar och ungdomar. De beskriver svårigheter i samband med att vara beroende av föräldrar och vuxna samt en osäkerhet i hanteringen av sjukdomen vilket kan förvärra situationen. Att tidigt involvera tonåringarna och ungdomarna i deras egenvård kan hjälpa dem att känna sig mer självsäkra och bli självständiga i hanteringen av sjukdomen. / Background: Type 1 diabetes is an autoimmune disease which is treated with insulin, good eating habits and physical activity. The disease is more common in children and young people who describe difficulties to balance their self-care with their everyday life. Aim: To elucidate teenagers and young people's experiences of living with type 1 diabetes. Method: A literature study was performed.  Eight qualitative articles was included in the results and was analyzed according to Friberg’s method for literature review. Results: Five categories were created during the analysis: The relationships to the surrounding, support and lack of support from the surroundings, lost autonomy, emotional and physical reactions and management and adjustment. Conclusions: Living with type 1 diabetes can be tough for teenagers and young people in many ways. They describe difficulties associated with being dependent of parents and adults as well as insecurity in the management of the disease which might worsen the situation. To involve teenagers and young people in self-care activities at an earlier age might help them to feel more confident and become more independent in the management of the disease.

Introduction: Type 1 diabetes is a chronic disease that affects the individual in everyday life. The diabetes team sets the treatment goals together with the patient aiming for a good quality of life and to prevent complications. The diabetes nurse should include in-depth knowledge of the daily life of people with diabetes, and have respect for the individual's choices and life situation. Aim: To describe how people with type 1 diabetes experience the support from the diabetes nurse. Method: A qualitative content analysis with an inductive approach has been used. A secondary analysis including semi-structured interviews with 15 adults (> 18 years) with type 1 diabetes was conducted. Result: The result was summarized with an overall theme "At the clinic - experience of the support offered" describes how people experience the support from their diabetes nurse. The theme constituted three categories "Access to the diabetes nurse", "The diabetes nurse - a source of information and knowledge that might need to be complemented with the support from other professionals" and,"Mutual trust - the patient's experience of the district nurse as a discussion partner and support". Conclusion: The results showed that the accessibility to diabetes nurses was experienced as good. It was simple and easy to make contact. The diabetes nurses were experienced to be engaged and provide good support to the patients. A good dialogue with the diabetes nurse and commitment from the diabetes nurse were mentioned as important factors that made the visits to be experienced as good and important. There were requests for greater access and expanded opportunities for help from counselors, as well as an increased focus on how the person is feeling. / Introduktion: Diabetes typ 1 är en kronisk sjukdom som påverkar personen i vardagen. Diabetesteamet sätter upp mål tillsammans med patienten om dennes behandling för att få en bra livskvalitet och motverka komplikationer. Diabetessjuksköterskan bör bland annat ha fördjupade kunskaper om det dagliga livet för personer med diabetes samt ha respekt för den enskilde individens val och livssituation. Syfte: Att beskriva hur personer med diabetes typ 1 upplever stödet från diabetessjuksköterskan. Metod: En kvalitativ innehållsanalys med en induktiv ansats har används. En sekundäranalys har gjorts där semistrukturerade intervjuer med 15 vuxna (>18 år) med diabetes typ 1 inkluderats. Resultat: Resultatet sammanfattades med ett övergripande tema "Att komma till mottagningen - upplevelsen av stödet i den vård som erbjuds" som handlar om hur personer upplever stödet från sin diabetessjuksköterska. Temat bestod av tre kategorier "Tillgänglighet till diabetessjuksköterskan ", "Diabetessjuksköterskan - en källa till information och kunskap som kan behöva kompletteras med andra yrkesgrupper" och "Ett ömsesidigt förtroende – patientens upplevelse av diabetessjuksköterskan som diskussionspartner och få stöd". Konklusion: Resultatet visade att tillgängligheten till diabetessjuksköterskorna upplevdes god. Det var enkelt och lätt att ta kontakt. Diabetessjuksköterskorna upplevdes vara engagerade och ge ett bra stöd till patienterna. En bra dialog med diabetessjuksköterskan och engagemang från diabetessjuksköterskan nämndes som viktiga faktorer som gjorde att besöken kändes bra och betydelsefulla. Det framkom önskemål om ökad tillgänglighet och utökade möjligheter till hjälp från kuratorer, samt ett ökat fokus på hur personen mår.

Formalized epidemiological field investigations were conducted to compare and contrast the transmission dynamics of EHV-1 neurological disease among horses stabled at Churchill Downs Racetrack, Louisville, Kentucky and of EHV-1 respiratory illness among horses stabled in the student barn at Murray State University. Differences were assessed by means of statistical and mathematical modeling techniques applied to survey and biological data collected over the course of the respective disease events. Regression methods applied to survey data enabled the construction of a statistical model to predict a date of onset of illness for horses within each equine cohort. Comparisons of the epidemic curves revealed that the Murray State University outbreak was 4.5 times longer (9 weeks versus 14 days) than the Churchill Downs Racetrack event. Survival analysis was used to explore the relationship between time to infection for each equine cohort. Horses stabled in the affected barn at Churchill Downs racetrack had a 3.02 times greater daily risk (p < 0.001) for contracting EHV-1 infection relative to horses stabled in the student barn at Murray State University. Estimates of the basic R0 number, calculated using mathematical formulae that incorporated the duration of the infectious period for neuropathogenic and nonneuropathogenic strains of EHV-1, were 10.25 and 2.94 for the Churchill Downs racetrack and Murray State University outbreaks, respectively. The generation time for the Churchill Downs outbreak was 6.1 times shorter (0.39 days versus 2.38 days) than for the Murray State University event. An assessment of the temporal occurrence of symptomatic infection is similar for each event and suggests that the appearance of clinical illness is constant over the course of an outbreak. A Reed-Frost model was constructed for each EHV-1 event where values of the transmission parameters (q, p and k) were estimated by fitting a model that most closely matched the observed profile of EHV-1 cases. The value of prophylactic vaccination on the spread of EHV-1 was assessed by making adjustments to these fitted models for varying levels of herd immunity. The results indicate that the prevention of EHV-1 neurological illness requires a higher level of herd immunity than EHV-1 respiratory illness.

The endoplasmic reticulum (ER) is the organelle responsible for synthesis and folding of secreted and membranous protein and lipid biosynthesis. It also functions as one of the main cellular calcium stores. Pancreatic beta-cells evolved to produce and secrete insulin upon demand in order to regulate blood glucose homeostasis. In response to increases in serum glucose, insulin synthesis represents nearly 50% of the total protein biosynthesis by beta-cells. This poses an enormous burden on the ER, rendering beta-cells vulnerable to agents that perturb ER function. Alterations of ER homeostasis lead to accumulation of misfolded proteins and activation of an adaptive response named the unfolded protein response (UPR). The UPR is transduced via 3 ER transmembrane proteins, namely PERK, IRE-1 and ATF6. The signaling cascades activated downstream of these proteins: a) induce expression of ER resident chaperones and protein foldases. Increasing the protein folding capacity of the ER; b) attenuate general protein translations which avoids overloading the stressed ER with new proteins; c) upregulate ER-associated degradation (ERAD) genes, which decreases the unfolded protein load of the ER. In severe cases, failure by the UPR to solve the ER stress leads to apoptosis. The mechanisms linking ER stress to apoptosis are still poorly understood, but potential mediators include the transcription factors Chop and ATF3, pro-apoptotic members of the Bcl-2 familly, the caspase 12 and the kinase JNK. Accumulating evidence suggest that ER stress contributes to beta-cell apoptosis in both type 1 and type 2 diabetes. Type 1 diabetes is characterized by a severe insulin deficiency resulting from chronic and progressive destruction of pancreatic beta-cells by the immune system. During this autoimmune assault, beta-cells are exposed to cytokines secreted by the immune cells infiltrating the pancreatic islets. Our group has previously shown that the pro-inflamatory cytokines interleukin-1beta (IL1-beta and interferon-gamma (IFN-gamma), via nitric oxide (NO) formation, downregulate expression and function of the ER Ca2+ pump SERCA2. This depletes beta-cell ER Ca2+ stores, leading to ER stress and apoptosis. Of note, IL1-beta alone triggers ER stress but does not induce beta-cell death, while IFN-gamma neither causes ER stress nor induces beta-cell death. Together, these cytokines cause beta-cell apoptosis but the mechanisms behind this synergistic effect were unknown. Type 2 diabetes is characterized by both peripheral resistance to insulin, usually as a result of obesity, and deficient insulin secretion secondary to beta cell failure. Obese patients have high levels of circulating free fatty acids (FFA) and several studies have shown that the FFA palmitate induces ER stress and beta-cell apoptosis. In the present work we initially established an experimental model to specifically activate the ER stress response in pancreatic beta-cells. For this purpose, insulinoma cells (INS-1E) or primary rat beta-cells were exposed to the reversible chemical SERCA pump blocker cyclopiazonic acid (CPA). Dose-response and time course experiments determined the best conditions to induce a marked ER stress without excessive cell death (<25%). The first goal of the work was to understand the synergistic effects of IL1-beta and IFN-gamma leading to pancreatic beta-cell apoptosis. Our group previously observed, by microarray analysis of primary beta-cells, that IFN-gamma down-regulates mRNAs encoding for some ER chaperones. Against this background, our hypothesis was that IFN-gamma aggravates beta-cell ER stress by decreasing the ability of these cells to mount an adequate UPR. To test this hypothesis, we investigated whether IFN-gamma pre-treatment augments CPA-induced ER stress and beta cell death. The results obtained indicated that IFN-gamma pre-treatment potentiates CPA-induced apoptosis in INS-1E and primary beta-cells. This effect was specific for IFN-gamma since neither IL1-beta nor a low dose CPA pre-treatment potentiated CPA-induced apoptosis in INS-1E cells. These effects of IFN-gamma were mediated via the down regulation of genes involved in beta cell defense against ER stress, including the ER chaperones BiP, Orp150 and Grp94 as well as Sec61, a component of the ERAD pathway. This had functional consequences as evidenced by a decreased basal and CPA-induced activity of a reporter construct for the unfolded protein response element (UPRE) and augmented expression of the pro-apoptotic transcription factor Chop. We next investigated the molecular regulation of the Chop gene in INS-1E cells in response to several pro-apoptotic and ER stress inducing agents, namely cytokines (IL1-beta and IFN-gamma), palmitate, or CPA. Detailed mutagenesis studies of the Chop promoter showed differential regulation of Chop transcription by these compounds. While cytokines (via NO production)- and palmitate-induced Chop expression was mediated via a C/EBP-ATF composite and AP-1 binding sites, CPA induction required the C/EBP-ATF site and the ER stress response element (ERSE). Cytokines, palmitate and CPA induced ATF4 protein expression and further binding to the C/EBP-ATF composite site, as shown by Western blot and EMSA experiments. There was also formation of distinct AP-1 dimers and binding to the AP-1 site after exposure to cytokines or palmitate. The third objective of this work was to obtain a broad picture of the pancreatic beta-cell molecular responses during and after (recovery period) a severe ER stress. For this purpose, we utilized an “in home” spotted microarray, the APOCHIP, containing nearly 600 probes selected for the study of beta-cell apoptosis. Time-dependent gene expression profiles were measured in INS-1E cells exposed to CPA. CPA-induced ER-stress modified expression of 183 genes in at least one of the time points studied. Most of theses genes returned to control levels 3h after CPA removal from the culture medium. We observed full beta-cell recovery and survival, indicating that these cells trigger efficient defenses against ER stress. Beta-cell recovery is associated with a sustained increase in the expression of ER chaperones and a rapid decrease of pro-apoptotic mRNAs following CPA removal. Two groups of genes were particularly affected by CPA, namely those related to the cellular responses to ER stress, which were mostly up-regulated, and those related to differentiated beta-cell functions, which were down-regulated. Among this last group, we observed a 40-90% decrease of the mRNAs for insulin-1 and -2. These findings were confirmed in INS-1E cells exposed to cytokines or thapsigargin (another SERCA blocker), and in primary beta-cells exposed to the same treatments. This decrease in insulin mRNA expression is due to transcript degradation, most probably caused by IRE-1 activation and triggering of its endoribonuclease activity, as recently described in Drosophila cells. In conclusion, our work enabled a better understanding of the pancreatic beta-cell responses to ER stress: 1.)We identified a sensitizing effect of IFN-gamma to ER stress in beta-cells via downregulation of key ER chaperones. 2.)We observed a differential regulation of Chop transcription by different treatments suggesting distinct responses of pancreatic beta-cells to diverse ER stress inducers. 3.)We provided the first global analysis of gene expression modifications in pancreatic beta-cells following ER stress. 4.)We demonstrated a high capacity of beta-cells to cope and recover from a severe ER stress. 5.)We identified a new protective mechanism against ER stress, namely the degradation of insulin mRNA which limits the load posed on the ER by insulin synthesis. This, coupled to a marked increase in ER chaperones and a fast degradation of pro-apoptotic mRNAs, enables beta cells to recover from ER stress after the causes of this stress are removed.