The purpose of gene mapping is to understand the underlying genetics of simple and complex traits like plumage colour and growth. This thesis is based on a cross between the wild ancestor of the modern chicken, the red junglefowl, and a White Leghorn line selected for high egg mass. There are obvious phenotypic differences between these two breeds in several aspects such as growth, egg production and behaviour. These complex traits are often influenced by a number of genes or Quantitative Trait Loci (QTL) as well as environmental factors. Identification of QTL regions involves testing of association between genetic markers and the phenotype of interest. The QTL identified in this study explain most of the difference in adult body weight between the red junglefowl and the White Leghorn, but less of the difference at earlier age. By applying a different method for detection of QTL, including gene interactions, epistasis, we can understand more of the genetics behind early growth. The allele coming from the red junglefowl is generally associated with lower weight, egg production and food consumption. In this study we have also identified two genes explaining the difference in plumage colour in the cross. The Extension locus, encoded by the melanocortin receptor 1 (MC1R), controls the amount of pigment produced has shown to be associated with plumage colour. A mutation in the MC1R gene causes black pigmentation of the plumage. We have also found association between the PMEL17 gene, known to be involved in normal pigmentation, and the Dominant white phenotype present in the White Leghorn. After comparison of sequences from different alleles at the Dominant white locus, amino acid alteration caused by insertion and deletion in the transmembrane region of the PMEL17 protein has been revealed. These mutations are associated with alleles representing different plumage colour variants.

In the field of transplantation, the increasing deficit of human donors have lead to an interest in animals as an alternative source of organs and tissues. Different in vitro systems and rodent models of xenotransplantation were used to examine the most significant barriers that have to be overcome, before isolated islets of Langerhans from pigs can be used as a cure for insulin-dependent diabetes mellitus in humans. In clinical transplantation, islets are infused into the liver through the portal vein. During this procedure the islets are susceptible to harmful innate reactions triggered in blood. Adenoviral vectors generating transgenic expression of human complement regulatory proteins were evaluated in pig islets and shown to confer protection against acute complement-mediated damage. Transplanted islets escaping this immediate destruction will be targets of a cellular immune response. Using a new mouse model of islet xenograft rejection, it was demonstrated that macrophages, effector cells in the rejection, were part of an MHC-restricted xenospecific immune response mediated by T cells. In a strain of knockout mice it was further shown that this process can proceed in the absence of an important signalling system, mediated by Toll-like receptors, between cells in innate and adaptive immunity. These findings illustrate some of the mechanistic differences compared to cellular islet allograft rejection which partly explain why immunosuppressive drugs used in clinical allotransplantation is not sufficient for preventing xenograft rejection. Porcine endogenous retroviruses (PERV) remain a safety concern in xenotransplantation. Characterization of PERV in pig islets indicated that virus expression is low in vitro but increases during the immediate time period following transplantation. This suggests that antiviral therapies administered at the time of transplantation could be used for preventing the risk of PERV transmission after xenotransplantation.

The overall aim of this thesis was to gain a deeper understanding about parents’ perceptions of quality of care and their own involvement in pediatric hospital care. Parental involvement in the care of hospitalized children has gained increased attention in recent years. The aim of this thesis was to study parental involvement in pediatric hospital care and investigate its association to the work conditions of pediatric hospital staff. The first study validated a parent questionnaire that measured parents’ views of the quality of care. The questionnaire measures quality of care by means of eight indices and an overall quality grade. Results showed that the questionnaire demonstrated satisfactory validity and reliability. Study 2 examined whether there were differences in quality ratings between respondents and non-respondents to the parent questionnaire. The main parent questionnaire was distributed in hospital and a follow-up questionnaire was sent home to a random sample of parents three week after the hospital visit. This study pinpointed a number of difficulties that need to be considered when conducting investigations of non-response. The third study aimed at gaining a deeper understanding of factors that influence parents’ views of their own involvement in pediatric care. Semi-structured interviews were conducted with parents of chronically ill children. Four themes emerged from the interviews: support, professionalism, work environment and responsibility. Underlying these four themes is a need for a clear communication between staff and parents. The fourth study examined hospital staff’s perceptions of parental involvement and possible consequences for staff work environment. A questionnaire was sent out to hospital staff at oncology, neurology and surgery units at three university children’s hospitals. Hospital staff on oncology units gave higher ratings to their workplace routines for involving parents in the child’s care, and experienced less work strain from parental demands, compared to staff on the other units. The results of this thesis indicate a clear association between parental involvement in pediatric care and the work conditions of pediatric hospital staff.

Socioeconomic inequalities in health and disability are found in all countries where social gradients have been studied. Despite rapid economic growth and expanding health care systems, aiming at providing services to people according to need rather than according to wealth, persistent and even widening health inequalities are found in Europe after the second World War. In this research project we wanted to establish a method for measuring socioeconomic status based on occupational groups and education in the HUNT Study, thereby providing tools for research in social medicine. A social gradient scale based on the occupational grouping from the HUNT study questionnaires had not been established. When this study was planned however, educational level, which might serve as a proxy for socioeconomic status, had been monitored in both HUNT I and HUNT II. Disability pension has been a central element in social security legislation in Norway, established as a universal right for all citizens in 1967. This public income-maintenance program protects workers in case of disability, and comprises both universal and earningrelated programs. The main eligibility criterion has been permanent impaired earning ability by at least 50 % for reasons of illness or disease, injury or disability. Despite objective health improvement in the population the last decades, incidence of disability pension has increased. In epidemiology, socioeconomic status is not only an important variable in itself. It is also a confounder that should be taken into consideration in discussing almost all causal relationships. Thus, in population based health studies, measures of socio-economic status are essential. Occupation, education and income together determine the socioeconomic status of a person. However, these factors are sufficiently distinct to require that they should also be studied separately in relation to health. To study them separately is often preferable since this can suggest hypotheses on causal relationships between exposure and disease.

During the past decades the knowledge concerning risk factors and pathophysiology of coronary heart disease (CHD) has substantially increased. However, despite identification of important risk factors CHD remains the leading cause of death in the western world. The metabolic syndrome is a cluster of metabolic disorders such as hypertension, hypertriglyceridemia, low HDL-cholesterol, and glucose intolerance associated with an increased risk of cardiovascular morbidity and mortality. The studies in this thesis are epidemiological in their character, and examine the relationships between different aspects of CHD and the metabolic syndrome in a population-based study of middle-aged men (ULSAM). The findings indicated that serum lipids were important risk factors for the development of both angina pectoris demanding revascularisation and acute myocardial infarction (MI). Proinsulin and blood pressure were independent predictors of MI only, suggesting these factors to be involved in thrombosis and plaque rupture. It was also found that antihypertensive treatment with beta-blockers and thiazide diuretics resulted in increased fasting blood glucose concentrations in subjects with an insulin resistant state with elevated proinsulin concentrations. Both proinsulin concentrations and increase in fasting blood glucose were associated with increased risk of developing future MI. The finding of a new Q/QS-pattern on the resting ECG, regardless of history of MI, was associated with impaired insulin secretion and was an independent predictor of total and cardiovascular mortality. A risk prediction score for MI including proinsulin and the ratio between apolipoprotein B and apolipoprotein A1 was developed in middle-aged men. This score was predictive for future fatal and nonfatal MI, and proved to be at least as good as the Framingham and the PROCAM scores, being based on traditional risk factors. In summary these studies provide further knowledge about the associations between CHD and the metabolic syndrome and the possible importance of new markers of cardiovascular risk such as proinsulin and the apolipoproteins.

Positron Emission Tomography (PET) permits regional myocardial perfusion, fibrosis and oxidative metabolism to be non-invasively quantified with radioactive tracers such as [15O]-water and [1-11C]-acetate. PET is an established research tool in congestive heart failure (CHF), a major cause of morbidity and mortality. However, as CHF is a syndrome that eventually affects all aspects of cardiac and systemic hemodynamic function, more clinically relevant information from a single PET scan is desirable. The aim of this thesis therefore was to develop and implement some new concepts in cardiac PET. A new method for the measurement of cardiac output with any tracer was validated in animal experiments and CHF patients. The early pulmonary retention of [1-11C]-acetate was inversely related to left ventricular (LV) function in animals and was directly proportional to lung water content and severity of LV diastolic dysfunction in patients. Eight patients with acute myocardial infarction were followed with serial PET from 3 hours to 3 weeks after trombolytic treatment. PET revealed that myocardial perfusion and the extraction and utilization of fuel substrates all decreased closer to the infarct centre. The rate of oxygen utilization within the infarct at 3 h predicted degree of myocardial fibrosis, pulmonary oedema and tissue viability at 3 weeks. Seventeen patients with CHF due to chronic ischemic cardiomyopathy and severely reduced LV function were evaluated with [1-11C]-acetate PET before and after coronary artery bypass surgery. There was a dramatic improvement in physical performance and symptoms, which was not correlated to the standard LV ejection indices. PET revealed that functional improvement was associated with improved LV loading conditions, reversed remodeling and homogenization of oxidative metabolism rather than increased output.

Reverse transcriptase (RT) is a crucial enzyme for retrovirus replication, and its presence in the virion is indispensable for infectivity. This thesis illustrates the use of RT activity assays as tools for quantitation and characterization of different retroviruses, particularly HIV. A non radioactive assay, using microtiter plates, for the RT of Moloney murine leukemia virus (MMuLV) was developed. Assay conditions for MMuLV and HIV-1 RT, together with isozyme specific RT activity blocking antibodies, were shown useful for discrimination between RTs from different retrovirus genera. RT activity assay for HIV-1 was found to quantitate different subtypes more equally efficient than p24 antigen assays did. Viral load (VL), the amount of HIV particles in the blood, is an important marker of the clinical status of an infected person. A method for VL determination based on RT activity (ExaVir Load) was developed. After plasma pretreatment, to inactivate cellular DNA polymerases, virions in patient plasma were immobilized on a gel, which was washed to remove disturbing factors. The virions were lysed with a detergent containing buffer and the lysate eluted. Finally, the RT activity in the lysate was determined and found to correlate strongly to VL by RNA according to a PCR based standard method (Roche Amplicor 1.5). The second version of the method was able to measure VL down to approximately 400 HIV-1 RNA copies/ml. The usefulness of RT from the VL procedure for determination of susceptibility towards anti-HIV drugs was demonstrated, and the results were in agreement with genotypic data. Due to its technical simplicity, and ability to detect a broad range of HIV-1 subtypes, ExaVir Load and the drug susceptibility application are interesting for clinical use, particularly but not only in resource limited settings. The concept is also potentially useful for research purposes, e.g. in combination with specific RT assay conditions.

Neurofibromatosis type-2 (NF2) is an autosomal dominant disorder with the clinical hallmark of bilateral eighth cranial nerve schwannomas. However, the diagnostic criterion is complicated by the presence of a variable phenotype, with the severe form presenting with additional tumors such as peripheral schwannoma, meningioma and ependymoma. We constructed a microarray spanning 11Mb of 22q, encompassing the NF2 gene, to detect deletions in schwannoma. Forty seven patients were analyzed and heterozygous deletions were detected in 45% of tumors. Using this array-based approach, we also detected genetic heterogeneity in a number of samples studied. Despite the high sensitivity and the comprehensive series of studied schwannomas, no homozygous deletions affecting the NF2 gene were detected <b>(paper I)</b>. In order to detect more subtle deletions within the NF2 locus, a higher-resolution gene-specific array was developed, for the detection of disease-causing<b> </b>deletions using a PCR-based non-redundant strategy. This novel approach for array construction significantly increased the reliability and resolution of deletion-detection within the NF2 locus <b>(paper II)</b>. To further expand the coverage of the 11 Mb microarray, we constructed the first comprehensive microarray representing a human chromosome for analysis of DNA copy number. This 22q array covers 34.7 Mb, representing 1.1% of the genome, with an average resolution of 75 kb <b>(paper III)</b>. Using this array, we analyzed sporadic and familial schwannomatosis samples, which revealed two commonly deleted regions within the immunoglobulin lambda locus and the GSTT1/CABIN1 locus. These regions were further characterized using higher-resolution non-redundant arrays, bioinformatic tools, positional cloning and mutational screening. Missense mutations were detected in the CABIN1 gene, which may contribute to the pathogenesis of schwannomatosis and therefore requires further study <b>(paper IV)</b>. Meningioma is the second most common NF2-associated tumor and loss of 1p has been previously established as a major genetic factor for disease initiation/progression and also correlates with increased morbidity. We analyzed 82 meningiomas using a chromosome 1 tiling-path genomic microarray. The distribution of aberrations detected supports the existence of at least four regions on chromosome 1, which are important for meningioma tumorigenesis <b>(paper V)</b>.

Microarray-based comparative genomic hybridization (array-CGH) has emerged as a versatile platform with a wide range of applications in molecular genetics. This thesis focuses on the development of array-CGH with a specific aim to approach disease-related questions through improved strategies in array construction and enhanced resolution of analysis. In <b>paper I</b>, we applied an array covering 11 Mb of 22q, encompassing the NF2 locus, for deletion detection in sporadic schwannoma. Hemizygous deletions and tumor heterogeneity were identified. Array-CGH was established as a reliable platform for detection of DNA dosage alterations. <b>Paper II</b> described the construction of the NF2 gene-specific microarray for high-resolution scanning of deletions in the NF2 locus. We report a novel PCR-based non-redundant strategy for microarray fabrication, which considerably improved the sensitivity and reliability of deletion detection. <b>Paper III</b> reported the first tiling-path array comprehensively covering a human chromosome. The usefulness of the 22q-array was demonstrated by applying it to detect DNA dosage-alterations in 22q-associated disorders. In <b>paper IV</b>, we optimized array-CGH protocols for deletion detection in 22q11 deletion-syndrome. We showed that genomic and cDNA clones are not optimal for analysis of 22q11 locus and that PCR-based non-redundant strategy is reliable for deletion detection in such regions. In <b>paper V</b>, we utilized the 22q-array for understanding the genetic basis of schwannomatosis. Two commonly deleted regions were identified within the IGL and the GSTT1/CABIN1 loci. Further investigations using high-resolution arrays, bioinformatic analysis and mutational screening were performed. Missense mutations, specific to the schwannomatosis- and NF2 samples, were identified in the CABIN1 gene. <b>Paper VI</b> described the first array-CGH study for comprehensive and high-resolution profiling of deletions spanning the 17q11 locus. Both typical and atypical deletions were identified in NF1 samples. Bioinformatic analysis revealed novel segmental duplications, which can potentially mediate 17q11 deletions.

Intra-articular glucocorticoid injection therapy is frequently used to relieve symptoms of arthritis, but there is considerable variation in injection routines among physicians. One issue of debate concerns the importance of synovial fluid aspiration during the injection procedure. In the present randomised controlled study of patients with rheumatoid arthritis (RA), a significantly reduced risk for arthritis relapse was observed when arthrocentesis was included in the intra-articular injection procedure of the knee. Furthermore, there is no consensus about the post-injection regimes. Previous studies have shown beneficial effects of post-injection rest of the knee, but also injection routines for other joints often include such recommendations. The present randomised controlled trial showed that 48-hour rest in elastic orthosis after intra-articular injection in the wrist did not improve the outcome. Thus, the effect of post-injection rest varies between different joints. The improved treatment result of post-injection rest of the knee is supposed to be caused by retarded steroid resorption from the joint. In order examine the metabolic effects in cartilage, bone and the hypothalamic-piuitary-adrenal (HPA)-axis, resting and mobile RA patients were studied after intra-articular knee injections. Serum levels of the injected glucocorticoid, triamcinolone hexacetonide (THA), were analysed, as well as cartilage oligomeric matrix protein (COMP) as a marker of cartilage turnover, osteocalcin for bone formation and deoxypyridinoline for bone resorption. The HPA-axis was assessed using serum levels of cortisol and adrenocorticotropine hormone. The result showed a short term and reversible suppression of the HPA-axis and bone formation, whereas bone resorption was unaffected. No differences between mobile and resting patients were observed. In both groups reduction of COMP levels were seen, but these were significantly more pronounced in resting patients, suggesting a cartilage-protective effect. The THA levels increased similarly in both groups, indicating that rest did not affect glucocorticoid resorption. Consequently, another explanation for the beneficial effects of postinjection rest of knee synovitis should be considered. In the present material the incidence of infectious complications of intra-articular treatment was less than 1/12,000 injections. The findings in this thesis can be applied in the clinical practice and should be considered when new guidelines for intra-articular glucocorticoid therapy are created.