| 51. |
- Angsten, Gertrud, 1948-
(författare)
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Fat metabolism : A clinical and experimental study with special reference to newborns
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lipid emulsion is an important constituent of total parenteral nutrition (TPN). In the investigations described in this thesis the effects of different lipid emulsions in neonates were studied.Twenty neonates in each of two studies, undergoing surgery for oesophago-gastrointestinal malformations, were assigned the day after the operation to receive TPN for 5 days, containing one of the two emulsions. In the first study 10 neonates received PFE 4501 containing gamma-linolenic acid (GLA) and carnitine and 10 were given Intralipid®and served as controls. In the second study 10 received Vasolipid® and 10, the control group, Intralipid®. In both studies linoleic acid and α-linolenic acid increased in plasma lipid esters and adipose tissue in each group. Arachidonic acid decreased in the PFE 4501 group in spite of GLA supplementation. Plasma carnitine increased two-fold in the PFE 4501 group, but decreased in the groups receiving Vasolipid® or Intralipid®. Reference ranges for muscle carnitine concentrations in children 1 days to 14 years of age were determined for comparisons. The results showed that the carnitine concentration in skeletal muscle tissue was greatly dependent on the gestational age in newborns. Accumulation of carnitine in skeletal muscle tissue continued during the first year of life, after which the concentration remained essentially constant. There are several methods for determining carnitine concentrations in plasma and muscle, but in the PET camera measurements are made in vivo. The transfer of long-chain fatty acids into the mitochondria, which relies on the carnitine-dependent transport system, was studied with PET, with labelling of the radioactive isotope carbon-11. Inhibition of carnitine palmitoyltransferase I by oxfenicine almost completely blocked the oxidative pathway of palmitic acid, while short carbon-chain fatty acids, which are independent of carnitine for their transport, were virtually unaffected. The fractional oxidative utilisation of long-chain fatty acids may thus be used as an index of the activity of the carnitine-dependent transport system.
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| 52. |
- Annerén, Cecilia
(författare)
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The Tyrosine Kinase GTK : Signal Transduction and Biological Function
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Protein tyrosine kinases play an important role in the regulation of various cellular processes such asgrowth, differentiation and survival. GTK, a novel SRC-like cytoplasmic tyrosine kinase, was recently cloned from a mouse insulinoma cell line and the present work was conducted in order to find a biological function of GTK in insulin producing and neuronal cells. It was observed that kinase active GTK-mutants, expressed in RINm5F cells, transferred to the cell nucleus and increased the levels of the cell cycle regulatory protein p27KIP1, reduced cell growth and stimulated glucagon mRNA expression. Furthermore, wild type GTK induces neurite outgrowth in the rat adrenal pheochromocytoma PC12 cell line, through activation of the RAP1-pathway, suggesting a role of GTK for cell differentiation. Studies using transgenic mice, expressing GTK under the control of the rat insulin 1 promoter, demonstrated a dual role of GTK for β-cell growth: Whereas GTK increases the β-cell mass and causes enhanced β-cell proliferation in response to partial pancreatectomy it also induced β-cell death in response to proinflammatory cytokines and impaired the glucose tolerance in mice treated with the β-cell toxin streptozotocin suggesting a possible role of GTK for β-cell destruction in Type 1 diabetes. We have also observed that GTK-transgenic islets and GTK-expressing RINm5F cells exhibit a reduced insulininduced activation of the insulin receptor substrate (IRS-1 and IRS-2)-pathways, partly due to an increased basal activity of these. GTK was found to associate with and phosphorylate the SH2 domain adapter protein SHB, which could explain many of the GTK-dependent effects both in vitro and in vivo. In summary, the present work suggests that the novel tyrosine kinase GTK is involved in various signal transduction pathways, regulating different cellular responses, such as proliferation, differentiation and survival.
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| 53. |
- Annuk, Margus, 1963-
(författare)
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Endothelium-Dependent Vasodilation and Oxidative Stress in Chronic Renal Failure
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cardiovascular disease (CVD) is the major cause of death in patients with chronic renal failure (CRF). Endothelial function and oxidative stress (OS) have previously been shown to be important in the pathogenesis of CVD. In this thesis, the endothelium-dependent vasodilatation (EDV) and OS were investigated in the patients with CRF. Also the influence of L-arginine, erythropoietin and diclofenac on EDV were evaluated in patients with CRF. Patients with CRF were found to be characterized by a defect EDV even after correction for traditional cardiovascular risk factors. This impairment was related to the degree of renal failure. Measurement of OS markers in CRF patients demonstrated that these patients were in a state of OS compared to healthy controls. The most informative indices to evaluate the degree of OS in CRF were: oxidized glutathione (GSSG) level, ratio between oxidized and reduced glutathione (GSSG/GSH ratio), lag phase of lipoprotein fraction (LPF) and baseline diene conjugation level of LPF. Simultaneously investigated OS markers and EDV demonstrated a relationship between OS and EDV in patients with CRF. EDV was positively correlated with total antioxidative activity, reduced glutathione (GSH) and lag phase of LDL. Local infusion of L-arginine as a substrate for nitric oxide synthesis and diclofenac as an inhibitor of cyclooxygenase-derived vasoconstrictive agents augmented EDV in patients CRF. In contrast, the erythopoietin treatment (both acute and long-term) impaired EDV in CRF patients. In conclusion, patients with CRF have increased levels of OS markers and impaired endothelial vasodilatory function. These factors may be important with respect to the high morbidity and mortality of CVD found in patients with CRF. One possible mechanism to reduce CVD in patients with CRF is to improve endothelial function and eliminate OS. Locally administrated L-arginine and diclofenae improved EDV but erythropoietin administration impaired EDV in patients with CRF.
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| 54. |
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| 55. |
- Antson, Dan-Oscar
(författare)
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Genotyping RNA and DNA using padlock probes
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Novel techniques are needed to investigate the genetic variation revealed in the first draft of the human genome sequence. Padlock probes are recently developed reagents, suitable for detecting single-nucleotide variations of DNA and RNA in situ or in solution. The probes are oligonucleotides of about 70-140 nucleotides that can be circularized by ligation in the presence of a correct target sequence. Standard chemical synthesis of padlock probes is difficult due to the requirement for intact 5' and 3' ends of these long oligonucleotides. A novel PCR-based method is presented in this thesis, whereby longer, densely labeled padlock probes can be made as compared to conventional chemical synthesis. PCR-generated padlock probes produced a stronger signal and a more resolved staining pattern, compared to chemically synthesized probes in fluorescence in situ analysis of an alpha-satellite sequence variant present in human chromosomes 13 and 21. Padlock probes used for in situ analysis of metaphase chromosomes had an optimal length of 140 nucleotides. They were used to identify individual chromosomes 7 and 15, and to follow the transmission of chromosome homologues for two consecutive generations. The specificity of the padlock probes to detect single copy genes in genomic DNA samples was demonstrated by detecting a single-nucleotide mutation in the ATP7B gene. It has not previously been known if T4 DNA ligase can be used for RNA sequence analysis. In this thesis, it is demonstrated that T4 DNA ligase can be used for distinguishing single-nucleotide RNA sequence variants. Reaction conditions were defined where most mismatches could be discriminated by a factor of 80 and all mismatches by a factor of at least 20. Under these conditions padlock probes could detect and distinguish RNA sequence variants with ligation efficiency almost as high as on the corresponding DNA sequence. A detailed study of the parameters influencing RNA-templated DNA ligation revealed that DNA ligation on RNA templates proceeds at a much slower rate compared to the same reaction on DNA, and that a molar excess of enzyme is required. Furthermore, the ligation reaction is inhibited by high concentrations of the cofactor ATP and NaCl. The work presented in this thesis demonstrates that PCR-generated padlock probes can detect and distinguish single-nucleotide variation in both RNA and DNA.
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| 56. |
- Appelberg, Jonas, 1964-
(författare)
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Ventilation and Lung Volume During Sleep and in Obstructive Sleep Apnea
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Obstructive sleep apnea (OSA) appears to affect up to 5% of the population. The extent to what pulmonary function awake and during sleep relates to obstructive breathing and hypoxemia during sleep in these patients is unclear. The aim of this study was to investigate respiratory function in patients with varying degree of snoring and OSA and to analyse regional lung aeration during sleep.In all, 35 healthy subjects and 90 patients with snoring and OSA were studied. The ventilatory response to CO2 (VRCO2) was measured. Lung function tests were performed. A technique based on computed tomography was developed to study lung aeration during sleep.Patients with OSA displayed a higher VRCO2 in comparison to healthy subjects and snorers (p<0.01). Increased closing volume and reduced expiratory reserve volume (ERV) were found in patients with OSA (p<0.001). In a multiple regression analysis, ERV was an independent predictor of nocturnal apnea (R2=0.13; p=0.001) and desaturation frequency (R2=0.11; p<0.01). In both healthy subjects and OSA patients, lung aeration was reduced during sleep by 0.10 ml gas/g tissue in the dorsal lung region (p<0.05 and p<0.01). OSA patients had a significantly lower gas/tissue ratio in comparison to healthy subjects both awake (-23%; p<0.04) and during sleep (-25%; p<0.04). In a univariate analysis, functional residual capacity (FRC) correlated with the change in lung aeration from wakefulness to sleep (r=-0.78; p<0.001). In patients with OSA, ERV (r=-0.69; p<0.05) and sleep time (r=0.69; p<0.05) correlated with the fall in lung aeration. In conclusion, patients with OSA display an increased ventilatory response to CO2, reduced ERV and increased closing volume. ERV predicts nocturnal apnea and desaturation frequency to a similar extent as obesity. Lung aeration is reduced in the dorsal region during sleep and patients with OSA display a lower amount of gas in comparison to healthy subjects. Decrease in lung volumes, promoting airway closure, and loss of muscle tone contributed to the altered lung function during sleep.
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| 57. |
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| 58. |
- Armulik, Annika
(författare)
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Studies on the transmembrane signaling of β1 integrins
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Integrins are heterodimeric cell surface receptors, composed of an α and a β subunit, mainly binding for extracellular matrix proteins. lntegrin subunit β1 can combine with at least 12 a subunits and thus form the biggest subfamily within the integrin family. In this thesis, functional properties of the splice variant β1Β, and the effects of several mutations in the cytoplasmic tail of integrin subunit β1Α were studied. In addition, the border between the transmembrane and cytoplasmic domains of several integrin subunits was determined.The β1Β splice variant has been reported to have a dominant negative effect on functions of β1Α integrins. In this study, it was studied if the expression of β1Β had similar negative effects on the αvβ3 integrin functions since the β3 subunit is structurally similar to β1Α. The β1Β subunit was expressed in an integrin β1-deficient cell line and it was found that the presence of β1Β does not interfere with adhesion or signaling of endogenous αvβ3The border between the cytoplasmic domain and the C-terminal end of the transmembrane domain of integrin α and β subunits has been unclear. This question was experimentally addressed for integrin subunits β1, β2, α2 and α5. It was found that integrin subunits contain a positively charged lysine, which is embedded in the membrane in the absence of interacting proteins.The functional importance of the lysine in integrin transmembrane domains was investigated by mutating this amino acid to leucine in β1Α. The mutation affected cell spreading and tyrosine phosphorylation of the adapter protein CAS. The activation of focal adhesion kinase and tyrosine phosphorylation of paxillin was not affected. Furthermore, the mutation of two tyrosines to phenylalanines in the β1Α cytoplasmic tail was found to reduce the capability of β1Α integrins to mediate cell spreading and migration. Activation of focal adhesion kinase in response to the later β1Α mutant was shown to be impaired as well as tyrosine phosphorylation of adapter proteins paxillin and tensin whereas overall tyrosine phosphorylation of CAS was unaffected. These data suggests the presence of focal adhesion kinase-dependent and -independent pathways for tyrosine phosphorylation of CAS after integrin β1Α-mediated adhesion.
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| 59. |
- Arrelöv, Britt, 1953-
(författare)
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Towards Understanding of Determinants of Physicians’ Sick-listing Practice and their Interrelations : A Population-based Epidemiological Study
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Physicians are supposed to act as sick-listing experts and they possess a role as gate-keepers to the social insurance system. Earlier studies have demonstrated variation between physicians and physician categories regarding sick-listing practice. In addition to the patient's disease and its severity, a number of other factors may be expected to influence sick-listing practice. Most earlier studies have focused on the patient's disease and his or her work place as cause for sickness absence.The aims of this study were to analyse variation of sick-listing practice between physician categories and the influence of physician characteristics on sick-listing practice, the influence of structure, organisation and remuneration of health care on physician sick-listing practice, the influence of local structural factors in the community, and the influence of a legislative change on physician sick-listing practice.The study was conducted as a cross-sectional epidemiological study of 57563 doctors’ certificates for sickness absence, received by 28 local social insurance offices in eight Swedish counties, during four months in 1995 and two months in 1996.Patient age, sex, and diagnostic group, issuing physician category, presence of a hospital in the municipality, municipality population size and county were all significantly and independently correlated to number of net days of sick-listing. Physician characteristics, such as age, sex and degree of specialisation were all associated with number of net days of sick-listing. Physicians working in general practice issued significantly shorter periods of sick-listing than the other physician categories. Reimbursement of general practice and participation in financial co-operation with social insurance were significantly correlated to length of sickness episode issued by general practitioners. A legislative change performed during the study period was associated with small effects in sick-listing practice.In conclusion, a number of factors other than disease and disease severity and other patient and physician linked factors were found to influence the variation of sick-listing practice. It appears that the closer the influencing factor was to the place were the decision was taken, i.e., the patient-physician consultation, the higher the impact on the decision appeared to be.
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| 60. |
- Arvidson, Johan
(författare)
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Autologous bone marrow transplantation in childhood : A follow-up study
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Autologous bone marrow transplantation (ABMT) was introduced to the Uppsala UniversityHospital in 1985. Since then, 50 children (<18 years of age) with haematological malignantdisease have been treated with ABMT. Most of these children had experienced a relapse oftheir disease, and ABMT was superimposed on preceding heavy treatment. The aim of thepresent study was to evaluate late adverse effects in five areas:Pulmonary and cardiac function were studied longitudinally. Six months after ABMT, adecrease in lung volumes and flow rates was observed in patients who received total bodyirradiation in their preparative regimen . There were signs of recovery during the following sixmonths, although incomplete. No further deterioration of pulmonary functioning wasobserved from the follow-up visit at 1 year after ABMT and thereafter. Cardiac function, asmeasured by echocardiography and radionuclide ventriculography, did not change frombefore ABMT until the last follow-up measurement (median 7 years post-transplant).Neuropsychological and psychosocial functioning were assessed in two cross-sectionalstudies. In addition, tests for general intelligence had been performed longitudinally.Intelligence test results did not change over time. Selective neuropsychological deficits andlearning difficulties were found despite normal results in general intelligence tests. Parentsand teachers reported more behavioural problems, mostly of the internalising type, andparents reported lower school competence relative to normative samples. According to theself-reports, most children were well adapted to the altered life conditions. It was concludedthat the psychosocial functioning seen in children treated with ABMT was dependent on thetype of informant used.Prepubertal growth was normal and relative height did not change from initial diagnosisexcept in those children treated with cranial irradiation before ABMT. Measurements ofgrowth hormone were made longitudinally, where all children showed signs of impairedspontaneous growth hormone secretion, irrespective of previous cranial irradiation orpreparative regimen.
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