published_or_final_version / abstract / Surgery / Doctoral / Doctor of Philosophy

published_or_final_version / Paediatrics and Adolescent Medicine / Doctoral / Doctor of Philosophy

published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

Since 1975, the extent of catching-up has been very different across Southern regions. Starting from the common arguments of growth theory, the paper wishes to show whether differences in regional income and growth can be attributed to different endowment in human capital, differences in private or public investment level, to structural imbalances, and labour force participation. The investigated panel consists of regional time series for the period 1975 to 1994 and includes NUTS II level regions of Greece, Spain, and the Italian South. Estimation of the impact of the variables on regional income is effected in a dynamic panel data model applying a GMM estimation procedure. The results indicate that the income level of Southern EU regions is largely determined by employment/educational levels and past public investment, while the impact of private investment is not significant. One may follow that EU regional policies should predominately focus on the human factor. Assistance to member countries to upgrade public infrastructures may be continued, but private investment incentives should be curbed. (author's abstract) / Series: Working Papers Series "Growth and Employment in Europe: Sustainability and Competitiveness"

Parkinson's disease is characterized by progressive degeneration of substantia nigra (SN) and subsequently loss of the nigrostriatal circuit. Many strategies have attempted to reconstruct this circuit but failed to satisfy clinical trials. The inhibitory environment of the adult CNS and the long distance between the SN and the striatum make true reconstruction difficult. To reconstruct this circuit, we used a transplant-pathway targeting model. Several putative pathway targeting molecules were examined for their ability to direct the growth of axons from a dopaminergic transplant. For a proof-of-principle study, adenoviral and lentiviral encoded glial cell line-derived neurotrophic factor (GDNF), GDNF-receptor alpha1 (GFRa1 ), or netrin-1 were injected along the corpus callosum individually or in combination. Treatment with individual factors leads to modest growth with few axons extending the entire length of the pathway. Combined treatment with either GDNF/GFRa1 or GDNF/netrin-1 induced the most robust growth towards the contralateral striatum. GDNF/netrin-1 showed the most consistent growth, with about 80% of the axons growing to the farthest injection site on the contralateral side. To determine if this combination of guidance molecules could be used to reconstruct the nigrostriatal pathway, we examined axon outgrowth from transplants placed within the SN in the 6-0HDA-Iesioned hemiparkinsonian animal model. A pathway from the SN to the striatum was made by injecting lentivirus encoding either GDNF and netrin-1 or GDNF and GFRa1, along the internal capsule, from the SN to the striatum. In another cohort of animals lentivirus encoding GFP was used as a control. A piece of embryonic VM tissue was transplanted into the SN two weeks after lentivirus injections. Compare to the GFP control group, a significantly greater number of dopaminergic axons grew from the transplants towards the striatum ten weeks after transplantation. Retrograde tract tracing showed the dopaminergic axons were from A9 cells in the transplant. Behavioral studies showed a significant reduction in number of amphetamine-induced rotations in GDNF/netrin-1 treated animals. Functional recovery strongly correlated with the number of dopaminergic fibers growing out from the transplant. This study shows that a functional nigrostriatal pathway can be reconstructed by guiding axonal growth from the dopaminergic neurons transplanted in the SN along a preformed growth-supportive pathway extending into the striatum. Refinement of this technique could be beneficial for PD patients in the future.

<p>Picropodophyllin (PPP) is an analogue of the anti tumour lignan podophyllotoxin with the unique ability to selectively inhibit the receptor of Insulin like growth factor 1(IGF-1). IGF-1 is believed to play an important part in development of the endometrium facing implantation. With PPP treated mice, studies can be made to measure gene expression from tissue of both treated and untreated mice to compare the role of IGF-1 regarding ovulation, implantation and receptivity. The aim of this study was to analyze gene expression of some steroid hormone receptors and cytokines in ovaries from mice treated with PPP. In this study, seven mice were treated with PPP at different times and tissue was collected. PCR-primers for cDNA sequences of estrogene receptor α, estrogene receptor β, progesterone receptor A, progesterone receptor B, growth hormone receptor, interleukin 1 α, interleukin 1 β, tumour necrosis factor α and androgen receptor were used. Real Time PCR was run with the samples and gene expression was measured. The results of this study showed that the inhibition of IGF-1 receptor interacted with IGF-1 which lead to altered levels of estrogene receptor alpha, progesterone receptor, growth hormone receptor and androgen receptor that can decrease ovulation. The results also showed the differences in gene products between treated and untreated samples, suggesting that IGF-1 plays an important role regarding ovulation.</p> / <p>Studier med hjälp av den selektiva insulinlika tillväxtfaktor 1 receptorn (IGF-1R) antagonisten; picropodof?phyllin (PPP), hur samspelet mellan livmoderslemhinnan och implantationsprocessen, samt hur ovulationen påverkas av insulinlika tillväxtfaktorn 1 (IGF-1) kan nu utföras. IGF-1 tros ha en viktig roll för den reproduktiva processen, där den påverkar ovulation, implantation och embryoutveckling. IGF-familjen består av tre ligander; insulin, IGF-1 och IGF-2. IGF transporteras bundet till bindarprotein (IGFBP). Medlemmarna i IGF receptorfamiljen kan binda IGF-1, IGF-2 och insulin fast med olika affinitet. PPP som är en cykloligan, är en analog från podofyllotoxin och fungerar som en syntetisk IGF-1 receptorantagonist, som selektivt inhiberar receptorns aktivitet. PPP tros även kunna nedreglera genexpression av receptorn. Tre tidigare projektarbeten har utförts på vävnader från möss injicerade med PPP. Tyngdpunkterna i dessa arbeten har legat på immunhistokemiska studier av IGF-1 i reproduktionsorgan från möss, uttryck av IGF-1, dess receptor och bindarprotein 1 i ovarier och uterus efter behandling med PPP. I denna studie användes vävnad samt cDNA från sju möss behandlade med PPP, i olika stadier av reproduktionen samt även icke behandlade möss. Studiens syfte var att med sanntids-PCR jämföra genuttryck från östrogenreceptor α och β, progesteronreceptor A och B, tillväxthormonreceptor, Interleukin 1 α och β, ’tumor necrosis’ faktor α samt androgenreceptor i vävnad från PPP-behandlade och obehandlade möss och genom de erhållna resultaten från ovarievävnaden utläsa effekten på ovulationen och från uterusvävnaden effekten på implantation och receptivitet. Studieresultaten visade att IGF-1s frånvaro gav förändrade nivåer av genprodukter, som medförde minskad ovulationen. Studien visade att IGF-1s roll vid ovulationen var väsentlig.</p>

The purpose of these studies was to determine whether lactogen-dependent Nb2-11c cells and lactogen-independent Nb2-SP cells differ with respect to morphology and autocrine growth control. To this end, the ultrastructural and surface morphology of both Nb2 cell lines was analyzed and the autocrine growth modulatory activity of Nb2 cell conditioned medium (Nb2-CM) was determined. The autocrine growth inhibitory activity of Nb2-CM was biologically characterized and attempts were made to biochemically characterize and purify the Nb2 cell autocrine growth inhibitor as well as to determine its mechanism of action. Quantitative analysis of transmission electron micrographs reveals that the ultrastructural morphology of lactogen-dependent Nb2-11c cells differs from that of lactogen-independent Nb2-SP cells. Nb2-11c cells exhibit a greater incidence and volume density of nuclear pockets, whereas the incidence and volume density of lipid droplets is greater in the Nb2-SP cell line. Surface feature of Nb2-11c and Nb2-SP cells, as examined with scanning electron microscopy, and indistinguishable. Nb2-11c and Nb2-SP cells share a common mode of growth control in the form of constitutive secretion of an autocrine inhibitory factor. Medium conditioned by either Nb2-11c or Nb2-SP cells inhibits the growth of both cell lines. Nb2-CM-mediated growth inhibition is dose-dependent and reversible. Nb2-CM does not induce quiescence or cell death, but rather, causes a delay in the progression of cells through all phases of the cell cycle. Nb2 cell proliferation stimulated by a variety of mitogens is inhibited by Nb2-CM. Nb2-CM also has the ability to inhibit the growth of normal rat splenocytes as well as MCF-7 human breast cancer cells. Biochemical analysis of Nb2-CM was equivocal; however, indirect evidence suggests that the autocrine growth inhibitory factor produced by Nb2 cells may be a prostaglandin or another arachadonic acid metabolite since the growth inhibitory activity of Nb2-CM is reduced when CM is prepared in the presence of indomethacin. Interestingly, levels of prostaglandin F₁(α) are elevated in CM-treated culture supernatants. Examination of other signal transduction systems in Nb2 cells suggests that neither cAMP activation, polyamine biosynthesis, nor protein kinase C activation mediate or influence the inhibitory effect of Nb2-CM.

The variation in wood density within growth rings was determined from X-ray negative images of wood samples of Gmelina arborea. The within-tree and between-tree comparisons showed that no two growth rings had exactly similar patterns of variation in the radial direction. The proportions of wood in four within-ring density classes were estimated. The variations in the proportions of wood in the four classes with age were nonlinear. On the average, the proportion of low density wood decreased with increasing age, while the proportion of high density wood increased with age. Regression analysis testing different curvilinear models showed that 37 to 99 per cent of the variations in the proportions of wood were associated with variations in age. Maximum and minimum ring density were negatively correlated with dry season rainfall. Variations in the proportion of high density wood and mean ring density were not associated with corresponding variation in dry season rainfall. The proportions of low and high density wood, mean ring density, maximum ring density and minimum ring density were not determined by annual rainfall.

Mammalian skeletal muscle can regenerate after injury and this response is primarily mediated by the satellite cell, a muscle stem cell. Following injury, satellite cells are activated to myoblasts, undergo rapid proliferation, migrate towards the injury site, and subsequently differentiate into myotubes in order to facilitate functional muscle repair. Fibrosis, caused by the secretion of structural extracellular matrix (ECM) proteins such as collagen I and fibronectin, by fibroblasts, impairs complete functional repair of the muscle. In this study, the role of the microenvironment during wound conditions was assessed by analysing the effect of specific extracellular matrix and growth factors on myoblast migration. The role of the Rho/ROCK pathway as a possible mechanism in mediating the effects seen was investigated. In order to analyse wound repair in an in vitro setting, we optimised and improved a wound healing model specifically designed for skeletal muscle repair. To this end we also developed a co-culture assay using primary myoblasts and fibroblasts isolated from the same animal. The studies showed that collagen I and fibronectin both increased myoblast migration in a dose-dependent manner. Decorin displayed opposing effects on cellular movement, significantly increasing collagen I-stimulated, but not fibronectin-stimulated, migration of myoblasts. ROCK inhibitor studies revealed a significant increase in migration on uncoated plates following inhibition with Y-27632 compared to untreated control. When cells were cultured on ECM components (Matrigel, collagen I, or fibronectin), the inhibitory effect of Y-27632 on migration was reduced. Analysis of ROCK and vinculin expression, and localization at the leading front, showed that ROCK inhibition resulted in loosely packed focal adhesion complexes (matrix dependent). A reduced adhesion to the ECM could explain the increased migration rates observed upon inhibition with Y-27632. We also investigated the role of TGF-β and decorin during wound repair, as TGF-β is a known pro-fibrotic agent. TGF-β treatment decreased wound closure rates; however, the addition of decorin with TGF-β significantly increased wound closure. The addition of ECM components, Matrigel and collagen I enhanced the effect seen in response to TGF-β and decorin; however, fibronectin negated this effect, with no increase in migration seen compared to the controls. In conclusion, the importance of extracellular matrix components in regulating myoblast migration and therefore skeletal muscle wound repair was demonstrated. We emphasize that, in order to gain a better understanding of skeletal muscle wound repair, the combination of ECM and growth factors released during wounding need to be utilised in assays which mimic the in vivo environment more closely. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Pancreaic stem cells are potent to differentiate into insulin producing -cells. Stem cells would be use for the cell therapy in the future. This diploma thesis is focused on this four transcription factors (LIF, noggin, TGF- a BMP-2) and their effects on the differentiation of the pancreatic stem cells into -cells. The results were analysed by evidential methods (RT-PCR, immunofluorescence and static incubation.