This thesis focuses on the identification of genetic factors underlying two inherited human phenotypes: hearing loss and monoamine oxidase activity. Non-syndromic hearing loss segregating in a Swedish family was tested for linkage to 13 previously reported candidate loci for hearing disabilities. Linkage was found to two loci: DFNA12 (llq22-q24) and DFNA2 (lp32). A detailed analysis of the phenotypes and haplotypes shared by the affected individuals supported the hypothesis of digenic inheritance of hearing disability in the Swedish family. Mutation screening of α-tectorin, a gene residing within the DFNA12 region revealed a mutation of a conserved amino acid (Cys to Ser), that segregated with the disease. The identification of the mutation added support to the involvement of α-tectorin in hearing disabilities. In contrast, no mutations were identified in two candidate genes at the DFNA2 locus, that were reported to cause hearing loss in other families. It is possible that the DFNA2 locus contains a third, not yet identified, hearing loss gene. Monoamine oxidase A (MAOA) and B (MAOB) catalyze the degradation of certain neurotransmitters in the central nervous system and are associated with specific behavioral and neuropsychiatric human traits. Activity levels of both monoamine oxidases (MAO) are highly variable among humans and are determined by unknown genetic factors. This study investigated the relationship of different MAO alleles with MAO mRNA levels and enzyme activity in human brain. Several novel DNA polymorphisms were identified in a group of Swedish individuals. Haplotypes containing several closely located MAOA polymorphisms were assessed in Asian, African, and Caucasian populations. The haplotype distribution and diversity pattern found among the three populations supported the occurrence of a bottleneck during the dispersion of modem humans from Africa. Allelic association studies conducted on postmortem human brain samples, revealed the association between a SNP in the MAOB intron 13, and different levels of both MAO enzyme activities. This suggested that this SNP is in linkage disequilibrium with at least one novel functional DNA polymorphism that controls MAO enzyme activities in human brain. The identification of functional polymorphisms regulating the activity of these enzymes will help to elucidate the involvement of MAO in human behavior and neuropsychiatric conditions.

The Mad/Max/Myc transcription factor network takes part in the control of vital cellular functions such as growth, proliferation, differentiation and apoptosis. Dimerization with the protein Max is necessary for the Myc-family of oncoproteins and their antagonists, the Mad-family proteins, to regulate target genes and carry out their intended functions. Myc functions as a positive regulator of proliferation, antagonized by the growth inhibitory Mad-proteins that potentially functions as tumor supprerssors. Deregulated Myc expression is found in a variety of tumors and signals negatively regulating Myc expression and/or activity could therefore be of potential use in treating tumors with deregulated Myc. Our aim was to therefore to investigate possible negative effects on Myc expression and activity by growth inhibitory cytokines and by the Myc antagonists, the Mad-family proteins.Two different cellular model systems of neuronal and hematopoietic origin have been utilized for these studies. Our results show that Mad1 is upregulated during induced neuronal differentiation of SH-SY5Y cells. Further, the growth inhibitory cytokine interferon-g (IFN-g) was shown to cooperate with retinoic acid (RA) and the phorbol ester TPA in inducing growth arrest and differentiation in N-myc amplified neuroblastoma cell lines. In contrast to treatment with either agent alone, the combined treatment of TPA+IFN-g and RA+IFN-g led to upregulation of Mad1 and to downregulation of N-Myc, respectively, thus correlating with the enhanced growth inhibition and differentiation observed after combination treatment. Ectopic expression of an inducible Mad1 in monoblastic U-937 cells led to growth inhibition but did not lead to differentiation or enhancement of differentiation induced by RA, vitamin D3 or TPA. In v-Myc transformed U-937 cells Mad1 expression reestablished the TPA-induced G1 cell cycle arrest, but did not restore differentiation, blocked by v-Myc. The growth inhibitory cytokine TGF-b was found to induce Mad1 expression and Mad1:Max complex formation in v-Myc transformed U-937 cells correlating with reduced Myc activity and G1 arrest. In conclusion, our results show that the Myc-antagonist Mad1 is upregulated by growth inhibitory cytokines and/or differentiation signals in neuronal and hematopoietic cells and that enforced Mad1 expression in hematopoietic cells results in growth inhibition and increased sensitivity to anti-proliferative cytokines. Mad1 and cytokine-induced signals therefore seem to cooperate in counteracting Myc activity.

The onset of cigarette smoking begins primarily in adolescence, and prevalence of smoking among adolescents has been increased during the last ten years. The prevalence of adolescent smoking increases with age and is more common or at least as common in girls as in boys in most western countries. Until recently the intensive investigation on health effects of smoking has been mostly conducted among adults. In adolescence the long-term health consequences have been reviewed, but current health problems are probably more important to adolescents and may be more motivating for smoking prevention and cessation. Increased morbidity among adolescent smokers has been reported, but specific current health problems and medication use have received little attention. More Control of smoking is a primary health goal. An underlying premise for promotion of physical activity in adolescence is that it may mead to a healthy lifestyle persisting through adulthood. Encouraging participation in sports has been recommended as smoking prevention and as part of smoking cessation programs. Smoking habits within different types of sports has received less attention, and whether physical activity has an impact on lung function is debated. Adolescent smokers are often unsuccessful in quitting and difficult to recruit and retain in smoking cessation programs. Occasional smoking may be the strongest risk factor for daily smoking, but occasional smokers could be an important target group for smoking cessation who could be discouraged from moving into daily smoking status. The first aim of this thesis was to study associations between smoking and current health status by examining associations between daily smoking and subjective health problems (Paper 1), and gender specific effects on respiratory symptoms and lung function (Paper II). The associations between physical activity and lung function in never smokers and daily smokers were also assessed (Paper III). The second aim was to study factors that might be useful in smoking

Predisposition to autoimmune diseases such as, rheumatoid arthritis, diabetes, and multiple sclerosis, is caused by the effect of multiple genes and a strong influence from the environment. In this study, I have investigated genetic factors that confer susceptibility to rheumatoid arthritis in a rat model. This work has led to the identification of several chromosomal regions, containing uncharacterized genes that directly or indirectly are associated to the arthritis development in these rats. We have observed that timing, gender, and genetic interactions are features that play a part in the effect that these genetic factors exert. Unarguably, animal models for human disorders display differences to the human form of disease. An important fact is however that the same chromosomal regions are identified in both rodent and human studies, which suggests that there are genetic factors that we have in common, which are involved directly or indirectly with an autoimmune response. Focusing the interest on these similarities, and on the possibility to apply a wide set of genetic tools, make animal models an invaluable, and probably necessary, instrument to dissect the genetic component of complex disorders. To fully comprehend the genetic basis for a complex disorder like this, will require understanding of how multiple genes interact with each other to cause disease. We have been able to demonstrate that chronic arthritis, in a rat model for rheumatoid arthritis, is regulated by several genes and that these act during different temporal phases of the disease. These findings will hopefully contribute to our understanding of the etiology and progression of rheumatoid arthritis.

A previous model of morphological pathogenesis assumed that cervical carcinoma is of monoclonal origin and progresses through multiple steps from normal epithelium via CINS into invasive carcinomas. The aim of this study was to investigate the molecular mechanism of pathogenesis of cervical neoplasia. In the clonality study, we found that 75% (6/8) of informative cases of cervical carcinoma had identical patterns of loss of heterozygosity (LOH) in the multiple synchronous lesions, while the remaining cases had different LOU patterns. In an extensively studied "golden case", the multiple carcinoma and cervical intraepithelial neoplasia (CIN) lesions could be divided into several different clonal groups by the X-chromosome inactivation patterns, HPV 16 mutations and LOH patterns. The biggest clonal family included one CIN II, one CIN III and four carcinoma samples, while four other monoclonal families of carcinoma did not include CIN lesions. These results suggested that cervical carcinoma can be either monoclonal or polygonal and contains clones developing either directly or via multiple steps. In the study of HPV types and HPV16 variations, the results confirmed that specific HPV types are the cause of cervical carcinoma but failed to support the previous opinion that HPV16 E6 variants are more malignant than the prototype. We established a novel classification called oncogene lineage of HPV16, and found that additional variations of HPV 16 oncogenes might be a weak further risk factor for cervical carcinoma. In the study of LOH, we found that interstitial deletion of two common regions of chromosome 3p, i.e., 3p2l.1-3p2l.3, and 3p22, was an early event in the development of cervical carcinoma. The results showed that the hMLH1 gene, located in 3p22 and showing LOH in 43% of the studied cases, was not involved in the development of cervical carcinoma because neither the expression level of protein nor the gene sequence was altered in these cases. In summary, a suggested model of molecular pathogenesis of cervical carcinoma is as follows. Specific types of HPV infect one or more committed stem cells in the basal layer of the epithelium. Fully efficient LOH events turn one (monoclonal origin) or more (polyclonal origin) HPV-infected stem cells into carcinoma cells without CIN steps. Less efficient LOH events would lead to CIN steps where some other unknown factors require to be added to facilitate the formation of carcinoma. In the absence of LOH events no carcinoma develops from the HPV-infected stem cells.

Mast cells are essential effector cells in the immune system as they release several inflammatory mediators. An accumulation of mast cells has been described in inflammatory conditions such as asthma and allergic rhinitis. Increased mast cell number, in the skin and other organs, is also a characteristic in mastocytosis, a disease without an effective treatment. One explanation for the increase in mast cell number is migration of mast cells in the tissue. In our studies we utilised mast cell lines, including HMC-1; cell lines transfected with the c-kit gene; and in vitro developed mast cells. Our aim was to characterise, two variants of the HMC-1 cell line; the signalling pathways essential for mast cell migration towards TGF-β and SCF; and the mechanism regulating mast cell accumulation in mastocytosis. Our results help to explain inconsistent findings regarding mast cell biology when HMC-1 cells have been used as a model system. The two variants, which we name HMC-1560 and HMC-1560, 816, are used in different laboratories around the world. HMC-1560 and HMC-1560, 816 exhibited different characteristics regarding their karyotype, phenotype as well as their set of activating point mutations in the Kit receptor. Furthermore, divergent signalling pathways are of importance for mast cell migration towards TGF-β and SCF. The classical MAP kinase-signalling cascade was found to be of major relevance for TGF-β-induced migration. In contrast, this pathway had a modest impact on SCF-induced migration, which instead was highly dependent on p38 MAP kinase signalling. Finally, one mechanism for mast cell accumulation in mastocytosis appeared to be an activating point mutation in the gene for the Kit receptor. This mutation appeared to prone transfected cells and mast cell progenitors to a higher rate of migration towards SCF if compared with cells expressing wt Kit receptor. In conclusion, our results show the importance of two different MAP kinase signalling pathways and mutations in the Kit receptor for mast cell migration induced by various types of stimuli. This knowledge helps us to understand the mechanism

<b>Purpose.</b> The main aim of the present study was to evaluate the effect of a low fat, low lactose diet on acute and late gastrointestinal side effects of pelvic radiotherapy. We also wanted to evaluate if such a treatment would influence the patients health related quality of life (HRQOL) in any way. <b>Background</b>. Cancer therapies and their side effects may cause nutritional problems and malnutrition. Pelvic radiotherapy, a common treatment modality for patients with carcinoma of the endometrium or cervix, is associated with both acute and late side effects that may affect nutritional status. Acute injury may lead to impaired absorption of nutrients and fluid. The patients experience diarrhoea, weight loss, nausea and vomiting. Bile salt malabsorption may be a factor in the pathogenesis of the diarrhoea. In cases of bile salt malabsorption a low fat diet will cause decreased bile salt excretion and thereby relief of symptoms. This assumption was evaluated in a small, non-randomised study in 1985. The results indicated that a low fat diet may reduce the frequency of diarrhoea and use of anti-diarrhoeal agents during radiotherapy. These findings were regarded as promising and since nutrition management guidelines for radiation enteritis were lacking in the literature, a clinical trial was planned. <b>Methods</b>. The study was designed as an open randomised clinical trial and conducted at the Norwegian Radium Hospital (NRH). The intervention diet (low fat, low lactose) was to be followed during and six weeks after radiotherapy. Measurements were performed at basement, the 3rd and last week of radiotherapy, six week after and then every 8th week. The entire period was one year. In November 1993 the surviving patients were approached again and asked to complete a questionnaire package similar to the one completed during the clinical trial. The study population was recruited from the department of gynaecology at NRH. The main selection criteria were pelvic radiotherapy (dose above 40 Gy) age = 75 years and a WHO functional status = 2. Patients were consecutive included from May 1988 through May 1990 and 143 women were included. Seventy-one were assigned to the intervention diet and 72 to the control group. In November 1993, 94 women were alive without any known relapse and 79 (84%) accepted participation. The women registered use of Loperamid and the daily number and consistency of bowel movements. The data on bowel movements was categorised and used to evaluate if diarrhoea was present or not. Nutritional status was evaluated by the means of weight development, arm muscle circumference (AMC), serum transferring (STF) and serum albumin (s-Alb). Dietary intake was assessed by 48-hour recall prior to radiotherapy, 4-days unweighed dietary record during radiotherapy and 7-days weighed dietary records during follow-up. 24-hour urinary nitrogen was used to validate the food records. HRQOL was defined as the patients' self-reported subjective physical and psychosocial situation as a consequence of disease and treatment. It was measured with the EORTC Core Quality of Life Questionnaire 36-item version (EORTC QLQ-C36). <b>Results</b>. During the last week of radiotherapy 14 patients (23%) in the intervention group and 32 (48%) in the control group reported diarrhoea (p&lt; 0.01). The intervention group also used less anti-diarrhoea medication than the control group, 0.6 tablets per day versus 1.1 (p&lt;0.01). Six weeks after end of radiotherapy, no group differences were found with regard to bowel movements or medication. The intervention group had a lower energy intake than the control group during radiotherapy, 5.7 MJ versus 6.5 MJ (p&lt;0.05). The mean daily fat intake was respectively 34.3 g and 60.1 g (p&lt;0.001). The intervention group received a significant lower part of the energy from milk products, meats, fats and sugar than the control group, and consumed more energy from vegetables and fruits, cereals and fish. Weight loss was more pronounced in the intervention group (mean reduction of 2.6 kg versus 1.7 kg) than in the control group (ns) during treatment. Mean values of AMC, s-Alb and STF were within the reference range in both groups during the entire observation period. During the last week of radiotherapy six patients (9%) in the intervention group and 4 (6%) in the control group were mildly depleted (ns). At 12 weeks and after one year none of the patients could be categorised as malnourished. No major differences in HRQOL were found between the two groups during radiotherapy and one-year follow up. Within the control group an association between diarrhoea and deteriorated role functioning, physical functioning and fatigue was found during the last week of radiotherapy that was not found in the intervention group. Regarding late effects of radiotherapy (3-4 years after radiotherapy) both groups had more diarrhoea than in the general population, 23.8 versus 9.5 (p&lt;0.01). There was however a tendency to more pronounced diarrhoea in the control group (29.6 (SD=27.3)) than in the intervention group (19.4 (SD=25.4)) though not statistical significant. Substantial diarrhoea was associated deteriorated SF and fatigue. <b>Conclusions</b>. The intervention group had less diarrhoea and used less Loperamide during radiotherapy than the control group. This finding did not affect nutritional status since no differences in nutritional status were found between the two groups. Both groups had a reduced energy intake and weight loss during radiotherapy. In the control group diarrhoea increased fatigue and had negative effects on physical functioning and role functioning. The intervention did not lead to differences in late radiation injury and chronic diarrhoea 3-4 years after treatment but diarrhoea was most prominent in the control group. Diarrhoea as a late effect increased fatigue and had a negative influence on social well being.

Preeclampsia is a complex and variable maternal disturbance that ranges from a dramatic onset at early gestation to slowly developing symptoms towards term. Hypertension and renal involvement with proteinuria are cardinal signs, which are often accompanied by fluid retention, blood-clotting dysfunction, and reduced organ perfusion. HELLP (haemolysis, elevated liver enzymes, and low platelet count) syndrome is regarded as a variant of preeclampsia, and the fulminante disease, eclampsia, includes convulsions. Preeclampsia is the main cause of maternal and fetal morbidity and mortality in western countries (1, 2), and in Nordic countries, 17 percent of maternal deaths have been ascribed to preeclampsia (2). Antenatal care in Norway includes on average 12 doctor/midwife consultations per pregnancy (3), and since blood pressure monitoring and urinary testing are main aims of the consultations, preeclampsia is a pregnancy complication that also generates substantial societal costs. / Paper II, III, IV and V reproduced with permission of Elsevier, sciencedirect.com

Sex chromosomes are useful for the study of how factors such as mutation, selection, recombination and effective population size affect diversity and divergence. A comparison of gametologous introns in seven different bird species revealed a complete lack of diversity on the female-specific W chromosome. In contrast, Z had at least one segregating site in all examined species. This can be explained by the lower mutation rate and lower effective population size of W but also suggests that selection affects diversity levels on the non-recombining W chromosome. In a diverse set of chicken breeds, the Z chromosome showed reduced diversity compared to autosomes and significant heterogeneity in levels of variation. High variance in male reproductive success, leading to a reduced Z chromosome effective population size, can partly explain this observation. In addition, we suggest that selective sweeps frequently act on the Z chromosome and are responsible for a significant part of the observed Z reduction. Differences in the mutation rate of Z and W chromosome sequences indicate that the time spent in male germ line is important for the mutation rate, but does not exclude a specifically reduced mutation rate on the Z chromosome. Estimates of mutation rate in autosomal, Z- and W-linked chicken and turkey sequences indicate a slight reduction in the rate on Z. However, due to rate heterogeneity among introns this reduction is not significant and we cannot exclude male biased mutation as the single cause of rate variation between the chromosomal classes. Analysis of indel mutation rates in avian and mammalian gametologous introns show frequent occurrence of indels on both W and Y, excluding meiotic recombination as the only source of this type of mutation. The different indel rate patterns in birds (Z&gt;W) and mammals (X=Y) suggest that indels are caused by both replication and recombination.

Stroke is the third leading cause of death and the major course of long-term disabilities in industrialized countries. Most surviving stroke patients show some degree of spontaneous recovery, but persistent symptoms in sensorimotor and cognitive functions are common. The symptoms can be reproduced in experimental stroke models in rats by occlusion of the middle cerebral artery. Housing rats in an enriched environment (EE), i.e. group housing in a large cage with toys that are changed daily, increases neuronal plasticity in healthy rats and can also improve functional recovery after experimental stroke. The present thesis investigates the effect of EE on the recovery of sensorimotor and cognitive functions one month after focal cerebral ischemia in rats, with emphasis on the underlying molecular mechanisms. Furthermore, EE-induced effect on gene expression in healthy rats was investigated after different periods of EE-housing and at different time points of the day. We show an improved recovery of both sensorimotor and cognitive functions in rats housed in EE for one month after focal cerebral ischemia. The recovery of sensorimotor function correlated significantly to mRNA expression of the plasticity associated transcription factors NGFI-A and NGFI-B in hippocampus and cortical regions outside the infarct. Social interaction seems to be an important component for the beneficial effects of EE after focal cerebral ischemia. Microarray analysis of hippocampal gene expression after one month of postischemic environmental enrichment revealed no confirmable EE-induced changes that could explain the improved recovery in spatial memory. Interestingly, healthy rats housed in EE showed increased mRNA expression of NGFI-A and Krox-20 exclusively during the dark period of the day compared to rats housed in isolation. In addition, EE housed rats had a substantial diurnal variation in NGFI-A, Krox-20 and NGFI-B mRNA expression; this was absent in single-housed rats. EE-induced changes in gene expression are more evident during the dark period of the day, when rats are more active and can benefit from the stimulating environment. This is important to consider in future investigation of putative mediators of the EE-induced neuronal plasticity. In summary, these findings may contribute to an increased understanding of the underlying molecular mechanisms behind improved functional recovery in rats housed in enriched environment after focal cerebral ischemia.