Browsing by Title

Sort by: Order: Results:

Now showing items 999-1018 of 1648
  • Rahkonen, Petri (Helsingin yliopisto, 2014)
    Despite advancements in neonatal intensive care and increased survival of infants born extremely preterm, many of them still develop with motor, sensory, cognitive, and behavioral impairments. Predicting adverse neurodevelopmental outcome as early as possible is a challenge in neonatology. Structural neuroimaging methods partly fail to detect milder brain abnormalities that may interfere with later developmental outcome, and neurological assessment is more unreliable in the neonatal period than in childhood. Thus, additional methods are needed for earlier and more accurate recognition of extremely preterm infants with adverse neurodevelopmental outcome. The first purpose of this study was to assess the value of measuring higher cortical function by neurophysiological methods in predicting outcome of infants born extremely preterm. Second, we aimed to examine possible difficulties in behavioral somatosensory processing and in mother-child interaction and their associations with developmental outcome. The lack of somatosensory evoked magnetic fields from the secondary somatosensory cortex in magnetoencephalography at term equivalent age, reflecting abnormal higher cortical functioning during somatosensory processing, was associated with worse neuromotor outcome of extremely preterm infants at two years of corrected age, not foreseen with structural neuroimaging methods. Further, we showed that responses from the secondary somatosensory cortex can also be detected by measuring somatosensory evoked potentials during electroencephalography. The quality of mother-infant interaction in mother- extremely preterm child dyads did not differ from that in mother-term child dyads. However, among children born extremely preterm worse child adjustment and lower quality of maternal and dyadic behavior were associated with lower neurocognitive outcomes. Half of the children born extremely preterm presented atypical behavioral sensory processing at two years of corrected age. Sensation seeking was common in extremely preterm children with neonatal neuroanatomical lesions. In conclusion, the functional neurophysiological methods magnetoencephalography and measurement of somatosensory evoked potentials during electroencephalography hold promise as valuable additional tools in predicting outcome of children born extremely preterm. The quality of mother-infant interaction may play a significant role in optimizing cognitive outcome after extremely preterm birth. Atypical behavioral sensory processing in children born extremely preterm is common, but the pathogenesis and developmental significance of this phenomenon call for more research in the future.
  • Palmén, Tuula (Helsingin yliopisto, 2003)
  • Aaltonen, Petri (Helsingin yliopisto, 2006)
    End-stage renal disease is an increasingly common pathologic condition, with a current incidence of 87 per million inhabitants in Finland. It is the end point of various nephropathies, most common of which is the diabetic nephropathy. This thesis focuses on exploring the role of nephrin in the pathogenesis of diabetic nephropathy. Nephrin is a protein of the glomerular epithelial cell, or podocyte, and it appears to have a crucial function as a component of the filtration slit diaphragm in the kidney glomeruli. Mutations in the nephrin gene NPHS1 lead to massive proteinuria. Along with the originally described location in the podocyte, nephrin has now been found to be expressed in the brain, testis, placenta and pancreatic beta cells. In type 1 diabetes, the fundamental pathologic event is the autoimmune destruction of the beta cells. Autoantibodies against various beta cell antigens are generated during this process. Due to the location of nephrin in the beta cell, we hypothesized that patients with type 1 diabetes may present with nephrin autoantibodies. We also wanted to test whether such autoantibodies could be involved in the pathogenesis of diabetic nephropathy. The puromycin aminonucleoside nephrosis model in the rat, the streptozotocin model in the rat, and the non-obese diabetic mice were studied by immunochemical techniques, in situ -hybridization and the polymerase chain reaction -based methods to resolve the expression of nephrin mRNA and protein in experimental nephropathies. To test the effect of antiproteinuric therapies, streptozotocin-treated rats were also treated with aminoguanidine or perindopril. To detect nephrin antibodies we developed a radioimmunoprecipitation assay and analyzed follow-up material of 66 patients with type 1 diabetes. In the puromycin aminonucleoside nephrosis model, the nephrin expression level was uniformly decreased together with the appearance of proteinuria. In the streptozotocin-treated rats and in non-obese diabetic mice, the nephrin mRNA and protein expression levels were seen to increase in the early stages of nephropathy. However, as observed in the streptozotocin rats, in prolonged diabetic nephropathy the expression level decreased. We also found out that treatment with perindopril could not only prevent proteinuria but also a decrease in nephrin expression in streptozotocin-treated rats. Aminoguanidine did not have an effect on nephrin expression, although it could attenuate the proteinuria. Circulating antibodies to nephrin in patients with type 1 diabetes were found, although there was no correlation with the development of diabetic nephropathy. At diagnosis, 24% of the patients had these antibodies, while at 2, 5 and 10 years of disease duration the respective proportions were 23%, 14% and 18%. During the total follow-up of 16 to 19 years after diagnosis of diabetes, 14 patients had signs of nephropathy and 29% of them tested positive for nephrin autoantibodies in at least one sample. In conclusion, this thesis work could show changes of nephrin expression along with the development of proteinuria. The autoantibodies against nephrin are likely generated in the autoimmune process leading to type 1 diabetes. However, according to the present work it is unlikely that these autoantibodies are contributing significantly to the development of diabetic nephropathy.
  • Patrakka, Jaakko (Helsingin yliopisto, 2001)
  • Jansson, Linda (Helsingin yliopisto, 2013)
    The mammalian central nervous system (CNS) develops from multipotent neural stem or progenitor cells. During development the cells proliferate actively and differentiate into all the different cell types of the brain. Neurogenesis continues in the adult brain but to a much lesser extent than during development. Adult neurogenesis is influenced by many different factors, including insults to the brain and neurodegenerative disease. Neurotransmitters have been implicated as regulators of neurogenesis. The main excitatory neurotransmitter glutamate is linked to neural progenitor cell proliferation and differentiation as well as migration of newborn neurons. Glutamate is also involved in the pathogenesis of several neurological disorders and other factors linked to brain pathogenesis, such as hypoxia and acidosis, are known to influence neural progenitor cells. Elucidating the mechanisms governing stem/progenitor cell behavior during normal and pathological conditions will aid in the development of cell-based therapies for treating insult or disease within the CNS. The aim of this thesis was to study the role of glutamate receptor agonists and antagonists in differentiation and migration of neural progenitors and their progeny to increase the understanding of how this neurotransmitter influences these cells. In addition, the effects of brain-derived neurotrophic factor (BDNF) and the reactivity of the cells to conditions associated with ischemic stroke (hypoxia/acidosis) were studied. By utilizing the neurosphere model we found that differentiating neural progenitors initially mainly expressed and responded to stimuli through metabotropic glutamate receptor 5 (mGluR5) and that the expression and functional response of the receptor corresponded with the distribution of radial glial cells. Ionotropic alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainate (KA) receptors were also present during early differentiation and expressed mainly by neuron-like cells. The expression of mGluR5 decreased and the expression and functional maturity of AMPA/KA receptors increased with time in culture. Pharmacological blocking studies revealed that radial glial process extension and neuronal motility are regulated through both mGluR5 and AMPA/KA receptors, but that the receptors have opposing effects on these cellular mechanisms. After prolonged differentiation a small subpopulation of neuronal cells responding to stimulation with N-methyl-D-aspartate (NMDA) and gamma amino butyric acid (GABA) appeared. This subpopulation of cells was responsive to motogenic actions mediated by BDNF. In addition, we found that radial glial and neuron-like cells exhibited differences in resting membrane potential and intracellular pH and reacted differently when exposed to hypoxic and acidic conditions. This study contributes new information regarding neural progenitor cell characteristics and behavior when differentiated in the presence of or challenged with factors influencing neurogenesis, both during normal and pathological conditions. These findings may be useful in developing treatment programs for neurological disorders.
  • Kerosuo, Laura (Helsingin yliopisto, 2009)
    Neural stem cell characteristics affected by oncogenic pathways and in a human motoneuron disease Stem cells provide the self-renewing cell pool for developing or regenerating organs. The mechanisms underlying the decisions of a stem or progenitor cell to either self-renew and maintain multipotentiality or alternatively to differentiate are incompletely understood. In this thesis work, I have approached this question by investigating the role of the proto-oncogene Myc in the regulatory functions of neural progenitor cell (NPC) self-renewal, proliferation and differentiation. By using a retroviral transduction technique to create overexpression models in embryonic NPCs cultured as neurospheres, I show that activated levels of Myc increase NPC self-renewal. Furthermore, several mechanisms that regulate the activity of Myc were identified. Myc induced self-renewal is signalled through binding to the transcription factor Miz-1 as shown by the inhibited capacity of a Myc mutant (MycV394D), deficient in binding to Miz-1, to increase self-renewal in NPCs. Furthermore, overexpression of the newly identified proto-oncogene CIP2A recapitulates the effects of Myc overexpression in NPCs. Also the expression levels and in vivo expression patterns of Myc and CIP2A were linked together. CIP2A stabilizes Myc protein levels in several cancer types by inhibiting its degradation and our results suggest the same function for CIP2A in NPCs. Our results also support the conception of self-renewal and proliferation being two separately regulated cellular functions. Finally, I suggest that Myc regulates NPC self-renewal by influencing the way stem and progenitor cells react to the environmental cues that normally dictate the cellular identity of tissues containing self-renewing cells. Neurosphere cultures were also utilised in order to characterise functional defects in a human disease. Neural stem cell cultures obtained post-mortem from foetuses of lethal congenital contracture syndrome (LCCS) were used to reveal possible cell autonomous differentiation defects of patient NPCs. However, LCCS derived NPCs were able to differentiate normally in vitro although several transcriptional differences were identified by using microarray analysis. Proliferation rate of the patient NPCs was also increased as compared to NPCs of age-matched control foetuses.
  • Priyadarshini, Madhusmita (Helsingin yliopisto, 2013)
    Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease (AD). The quest for better therapies to modify the progression of PD is still ongoing. During the last two decades, the concept of the etiological basis of PD has changed, which has been driven by genetics, the recognition of familial forms, knowledge of the effects of the environment and toxins, and genome-wide association studies. Although most cases are sporadic, approximately 5-10% of PD cases are due to genetic mutations that give rise to the familial forms. Studies using neurotoxins and also genetic mutations that underlie familial PD have implicated mitochondrial dysfunction in the pathogenesis of PD. Among the different genes associated with familial PD, PTEN-induced putative kinase1 (Pink1), responsible for the autosomal recessive type, is strongly linked to the mitochondria. To investigate in depth the underlying mechanisms of Pink1, we inhibited the function of pink1 in zebrafish using morpholino oligonucleotides (MOs). The MO was first thoroughly characterized with all necessary control experiments to avoid unspecific effects. Since the dopaminergic system is affected in PD, a marker for dopamine, tyrosine hydroxylase (TH), was used to assess damage to the system. Due to a genome duplication event that occurred early in the evolution of teleosts after the divergence from the mammals, two TH non-allelic isoforms were identified in zebrafish: th1 and th2. In the pink1 morphants, both the TH gene isoforms were altered. With in situ hybridization, the loss of th1 was found in the ventral diencephalon (dopaminergic cell groups 5, 6, 11) and th2 was reduced in the caudal hypothalamus (cell group 10b). Similar results were obtained with the cell counting method for TH1 immunoreactive cells. TH-ir indicated the loss of cells in the pretectum (group 7) and the ventral diencephalic cluster represented by cell groups 5,6,11. These pink1 morphants were exposed to subeffective doses of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). This amalgamation of the toxin and genetic manipulation caused a locomotor deficit and also facilitated the loss of TH-ir in the same cell populations in the larval brains as was instigated by pink1 knockdown alone. To investigate the involvement of pink1 in cell damage, we used a two-color gene expression-based microarray and identified a number of genes that were potentially involved in the pathogenic mechanism of the disease. After successful data analysis, the changes in critical genes were successfully validated by quantitative real-time PCR. The gene expression changes in the morphants, identified by the microarray, were rescued by pink1 mRNA injections, suggesting the specific involvement of pink1 in the differentially expressed gene regulation. One of the significant findings was HIF signaling, an important pathway affected by pink1 knockdown. Individual factors and genes in the same pathway were validated by independent methods in the pink1 morphants to reveal whether pink1 affected hif1α or the cascade of events in the signaling pathway. Changes in the VEGF transcripts, erythropoiesis, and reactive oxygen species were observed, as were other antioxidant system genes, including cat and sod2. These pathways may provide new targets for drug development in PD. To study the mechanisms underlying the involvement of pink1 in oxidative stress-mediated PD pathology using zebrafish as a tool, we generated a transgenic line, Tg(pink1:EGFP). The Tol2 transgenic approach was used to generate Tg(pink1:EGFP) by using the zebrafish pink1 promoter. Expression of the pink1 transgene was detected in the telencephalon, midbrain, and rhombencephalon in the CNS, and in the muscle, heart, and liver among the peripheral organs. The transgenic fish line was used to study the effect of oxidative stress. When subjected to a low concentration of hydrogen peroxide (H2O2), which had no effect on the mortality or phenotype of the fish, the transgenic fish showed an increase in pink1 transgene activity in the brain of the larval zebrafish. Oxidative stress-mediated changes in TH expression are valuable for PD study. H2O2 administration did not affect the th1 transcript levels, but it significantly increased pink1 expression and reduced the th2 transcript levels. This transgenic model will be highly useful for drug development and the screening of new potential therapeutic approaches as an in vivo model.
  • Pischik, Elena (Helsingin yliopisto, 2006)
    Acute intermittent porphyria (AIP, MIM #176000) is an inherited metabolic disease due to a partial deficiency of the third enzyme, hydroxymethylbilane synthase (HMBS, EC:, in the haem biosynthesis. Neurological symptoms during an acute attack, which is the major manifestation of AIP, are variable and relatively rare, but may endanger a patient's life. In the present study, 12 Russian and two Finnish AIP patients with severe neurological manifestations during an acute attack were studied prospectively from 1995 to 2006. Autonomic neuropathy manifested as abdominal pain (88%), tachycardia (94%), hypertension (75%) and constipation (88%). The most common neurological sign was acute motor peripheral neuropathy (PNP, 81%) often associated with neuropathic sensory loss (54%) and CNS involvement (85%). Despite heterogeneity of the neurological manifestations in our patients with acute porphyria, the major pattern of PNP associated with abdominal pain, dysautonomia, CNS involvement and mild hepatopathy could be demonstrated. If more strict inclusion criteria for biochemical abnormalities (>10-fold increase in excretion of urinary PBG) are applied, neurological manifestations in an acute attack are probably more homogeneous than described previously, which suggests that some of the neurological patients described previously may not have acute porphyria but rather secondary porphyrinuria. Screening for acute porphyria using urinary PBG is useful in a selected group of neurological patients with acute PNP or encephalopathy and seizures associated with pain and dysautonomia. Clinical manifestations and the outcome of acute attacks were used as a basis for developing a 30-score scale of the severity of an acute attack. This scale can easily be used in clinical practice and to standardise the outcome of an attack. Degree of muscle weakness scored by MRC, prolonged mechanical ventilation, bulbar paralysis, impairment of consciousness and hyponatraemia were important signs of a poor prognosis. Arrhythmia was less important and autonomic dysfunction, severity of pain and mental symptoms did not affect the outcome. The delay in the diagnosis and repeated administrations of precipitating factors were the main cause of proceeding of an acute attack into pareses and severe CNS involvement and a fatal outcome in two patients. Nerve conduction studies and needle EMG were performed in eleven AIP patients during an acute attack and/or in remission. Nine patients had severe PNP and two patients had an acute encephalopathy but no clinically evident PNP. In addition to axonopathy, features suggestive of demyelination could be demonstrated in patients with severe PNP during an acute attack. PNP with a moderate muscle weakness was mainly pure axonal. Sensory involvement was common in acute PNP and could be subclinical. Decreased conduction velocities with normal amplitudes of evoked potentials during acute attacks with no clinically evident PNP indicated subclinical polyneuropathy. Reversible symmetrical lesions comparable with posterior reversible encephalopathy syndrome (PRES) were revealed in two patients' brain CT or MRI during an acute attack. In other five patients brain MRI during or soon after the symptoms was normal. The frequency of reversible brain oedema in AIP is probably under-estimated since it may be short-lasting and often indistinguishable on CT or MRI. In the present study, nine different mutations were identified in the HMBS gene in 11 unrelated Russian AIP patients from North Western Russia and their 32 relatives. AIP was diagnosed in nine symptom-free relatives. The majority of the mutations were family-specific and confirmed allelic heterogeneity also among Russian AIP patients. Three mutations, c.825+5G>C, c.825+3_825+6del and c.770T>C, were novel. Six mutations, c.77G>A (p.R26H), c.517C>T (p.R173W), c.583C>T (p.R195C), c.673C>T (p.R225X), c.739T>C (p.C247R) and c.748G>C (p.E250A), have previously been identified in AIP patients from Western and other Eastern European populations. The effects of novel mutations were studied by amplification and sequencing of the reverse-transcribed total RNA obtained from the patients' lymphoblastoid or fibroblast cell lines. The mutations c.825+5G>C and c.770T>C resulted in varyable amounts of abnormal transcripts, r.822_825del (p.C275fsX2) and [r.770u>c, r.652_771del, r.613_771del (p.L257P, p.G218_L257del, p.I205_L257del)]. All mutations demonstrated low residual activities (0.1-1.3 %) when expressed in COS-1 cells confirming the causality of the mutations and the enzymatic defect of the disease. The clinical outcome, prognosis and correlation between the HMBS genotype and phenotype were studied in 143 Finnish and Russian AIP patients with ten mutations (c.33G>T, c.97delA, InsAlu333, p.R149X, p.R167W, p.R173W, p.R173Q, p.R225G, p.R225X, c.1073delA) and more than six patients in each group. The patients were selected from the pool of 287 Finnish AIP patients presented in a Finnish Porphyria Register (1966-2003) and 23 Russian AIP patients (diagnosed 1995-2003). Patients with the p.R167W and p.R225G mutations showed lower penetrance (19% and 11%) and the recurrence rate (33% and 0%) in comparison to the patients with other mutations (range 36 to 67% and 0 to 66%, respectively), as well as milder biochemical abnormalities [urinary porphobilinogen 47±10 vs. 163±21 mol/L, p<0.001; uroporphyrin 130±40 vs. 942±183 nmol/L, p<0.001] suggesting a milder form of AIP in these patients. Erythrocyte HMBS activity did not correlate with the porphobilinogen excretion in remission or the clinical of the disease. In all AIP severity patients, normal PBG excretion predicted freedom from acute attacks. Urinary PBG excretion together with gender, age at the time of diagnosis and mutation type could predict the likelihood of acute attacks in AIP patients.
  • Nevalainen, Päivi (Helsingin yliopisto, 2010)
    Until recently, objective investigation of the functional development of the human brain in vivo was challenged by the lack of noninvasive research methods. Consequently, fairly little is known about cortical processing of sensory information even in healthy infants and children. Furthermore, mechanisms by which early brain insults affect brain development and function are poorly understood. In this thesis, we used magnetoencephalography (MEG) to investigate development of cortical somatosensory functions in healthy infants, very premature infants at risk for neurological disorders, and adolescents with hemiplegic cerebral palsy (CP). In newborns, stimulation of the hand activated both the contralateral primary (SIc) and secondary somatosensory cortices (SIIc). The activation patterns differed from those of adults, however. Some of the earliest SIc responses, constantly present in adults, were completely lacking in newborns and the effect of sleep stage on SIIc responses differed. These discrepancies between newborns and adults reflect the still developmental stage of the newborns’ somatosensory system. Its further maturation was demonstrated by a systematic transformation of the SIc response pattern with age. The main early adult­like components were present by age two. In very preterm infants, at term age, the SIc and SIIc were activated at similar latencies as in healthy fullterm newborns, but the SIc activity was weaker in the preterm group. The SIIc response was absent in four out of the six infants with brain lesions of the underlying hemisphere. Determining the prognostic value of this finding remains a subject for future studies, however. In the CP adolescents with pure subcortical lesions, contrasting their unilateral symptoms, the SIc responses of both hemispheres differed from those of controls: For example the distance between SIc representation areas for digits II and V was shorter bilaterally. In four of the five CP patients with cortico­subcortical brain lesions, no normal early SIc responses were evoked by stimulation of the palsied hand. The varying differences in neuronal functions, underlying the common clinical symptoms, call for investigation of more precisely designed rehabilitation strategies resting on knowledge about individual functional alterations in the sensorimotor networks.
  • Lonka, Liina (Helsingin yliopisto, 2004)
  • Vanhanen, Jenni (Helsingin yliopisto, 2015)
    Neuronal histamine and its H3 receptor (H3R) regulate several physiological functions and are involved in the pathophysiology of various central nervous system disorders such as Parkinson s disease, Alzheimer s disease, Tourette syndrome and narcolepsy. Studies conducted in experimental animals have also suggested a role for histamine and especially H3R in the effects of drugs of abuse. In this thesis, the main aim was to study how histamine and H3R regulate alcohol-related behaviors. Furthermore, our goal was to investigate the underlying mechanisms in the observed behaviors. By using both wild type mice in different background strains and genetically modified mice, we studied whether histamine and H3R regulate the behavioral responses to alcohol. Three different H3R antagonists (ciproxifan, JNJ-10181457 and JNJ-39220675) were used and it was found that both pharmacological antagonism and genetic knockout of H3R (H3R KO) lead to diminished alcohol consumption and reward. By using histamine deficient histidine decarboxylase knockout (HDC KO) mice, we found that the lack of histamine does not alter alcohol consumption or reward but histamine is indeed required for the H3R-mediated alcohol reward inhibition. We also found that JNJ-39220675 inhibited the acute stimulation of amphetamine, but failed to inhibit the rewarding properties of amphetamine. This indicates that although H3R antagonists inhibit alcohol reward, they may not possess the same ability on psychostimulants, such as amphetamine. The findings obtained from the behavioral experiments led us to hypothesize that H3R interacts with the dopaminergic system. This was further studied on a molecular level using both radioactive in situ hybridization and semi-quantitative Western blotting. We found that compared with control mice, H3R KO mice displayed lower levels of dopamine D1 receptor messenger RNA in the striatum, which is an area important in the regulation of e.g. reward. In addition, we found that activation of dopamine D1 and D2 receptors resulted in abnormal striatal cell signaling in the absence of H3Rs. Taken together, these findings demonstrate that H3R is an important regulator of alcohol-related behaviors. The mechanism by which H3R regulates these phenomena might involve the interaction between the striatal H3R and dopamine receptors. In addition, these results provide preclinical evidence that H3R antagonists may serve as a novel approach to treat alcohol dependence.
  • Carlsson, Emilia (Helsingin yliopisto, 2012)
    This thesis is based on the original observation of an allelic deletion of the recently described Neuron navigator 3 (NAV3) gene in patients with primary cutaneous T-cell lymphoma (CTCL) and CTCL-associated lung cancer. Thereafter mutations or copy number changes of NAV3 have been reported in melanoma, glioblastoma (GBM) and adrenal carcinoma. The aim of this study has been to shed light on the function and interactions of the NAV3 protein, as well as characterizing NAV3 copy number changes and their effect on patient survival in several forms of cancer. NAV3 is a novel cancer-associated gene at 12q21. The specific function of NAV3 is not known except that it carries actin-binding domains with ATPase activity, and is therefore likely to have an action on microtubules and cytoskeleton reorganization. The three Navigator genes, NAV1, NAV2 and NAV3 share homology among themselves and among different species. This suggests a central role for the encoded proteins in cell biology. In this study, NAV3 copy number changes have been studied by fluorescence in situ hybridisation (FISH) and array comparative genomic hybridisation (aCGH) in non-melanoma skin cancers, colorectal cancer and neural system tumours, and the relevant NAV3-regulated target genes have been identified. Furthermore, the expression levels of NAV3 and NAV3-regulated signalling molecules have been correlated to disease progression and patient outcome. In Basal cell carcinomas (BCC) and Squamous cell carcinomas (SCC) we found NAV3 copy number loss and corresponding absence of protein in 21% of the BCC and in 25% of the SCC tumours. In the nodular/superficial BCC subgroup, also low-level NAV3 amplification was found. NAV3 aberrations were independent of the known chromosome 6 amplification in BCC. Chromosome 12 polysomy, also independent of chromosome 6 polysomy, was found in 33% and 25% of the invasive type of BCC and in SCC, respectively. In colorectal carcinomas NAV3 deletion and chromosome 12 polysomy were detected in 30% and 70% of MSS carcinomas, and in 12.5% and 50% of MSI carcinomas, but also in 23% and 30% of adenomas, respectively. Low copy number amplification of NAV3 was found in 25% of MSS samples. 119 patient samples representing different central and peripheral nervous system tumours were studied for NAV3 copy number changes. Neuronally differentiated tumours (neuroblastomas and medulloblastomas) entailed more NAV3 aberrations than the glial tumours. In glial tumours, those with grade IV (gliobalstoma (GBM)) had significantly more NAV3 deletions than tumours with grades I, II or III. Log rank analysis also linked NAV3 deletion to a poor prognosis in gliomas. In contrast, glioma patients with NAV3 amplification showed better prognosis than those with normal NAV3 copy numbers. The FISH result was also supported by aCGH analysis, which showed results matching the FISH analysis for tumour samples with NAV3 amplification and deletion. To understand the in vivo functional consequences of NAV3 copy number changes, especially of NAV3 deletion, we silenced NAV3 in normal colon, GBM and primary keratinocyte cells, using a commercially available small inhibitory ribonucleic acid (siRNA) construct. Post transfection RNA samples from several time points were analyzed with Agilent 44K microarray. In GBM and colorectal cell lines we identified, among others, GnRHR and IL-23R as upregulated by NAV3 gene silencing. The upregulation of the selected genes were confirmed by quantitative PCR. In primary keratinocytes, NAV3 silencing led to consistent upregulation of 22 annotated genes, and several Wnt/HH pathway genes were slightly overexpressed too. Taken together the results of this thesis support the previously suggested role of NAV3 as a novel cancer associated gene, and we suggest that NAV3 affects the malignant potential of a given tumour through multiple pathways. This assumption is based on the fact that gene expression analysis of NAV3 silenced cells indicates that NAV3 affects genes with involvement in both inflammation and carcinogenesis.
  • den Hollander, Bjørnar (Helsingin yliopisto, 2015)
    In recent years there has been a large increase in the use of a new kind of amphetamine- type stimulants known as substituted cathinones. These compounds have a short history of human use, and little is known about their potential neurotoxicity. Two of the most popular substituted cathinones, 4-methylmethcathinone (4-MMC, mephedrone) and 3,4- methylenedioxymethcathinone (MDMC, methylone} are, aside from their β-ketone group, close structural analogues of potentially neurotoxic amphetamines such as methamphetamine (METH) and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy). This has led to concern about the potential neurotoxicity of these novel compounds, and warrants a closer investigation into their possible long-term neurotoxic effects. METHODS The long-term effects of METH and MDMA as well as 4-MMC and MDMC were assessed using a range of biochemical assays, including assessment of monoamine levels and their transporters. The effects on brain activity were investigated using manganese-enhanced magnetic resonance imaging. Furthermore, behavioral experiments assessing cognition and neuropsychiatric function were performed. Finally, in vitro experiments in a neuroblastoma cell line were performed to identify mechanisms responsible for the observed differences in toxicity between the amphetamines and cathinones. RESULTS Unlike METH and MDMA, which produced strong reductions in dopamine and serotonin levels or brain activation, 4-MMC produced few notable effects on monoamine levels and had only minor effects on brain activation, although MDMC produced a reduction in 5-HT levels similar to MDMA. No clear effects on behavioral tests of memory function were observed as both increases and decreases in test performance were seen following 4- MMC and MDMC. In vitro experiments revealed that cathinones differ from amphetamines in their redox properties, and 4-MMC produced different effects than METH on the mitochondrial electron transport chain. CONCLUSIONS The substituted cathinones 4-MMC and MDMC do not appear to be more neurotoxic than METH and MDMA. If anything, they show a more favorable safety profile. Therefore, these substances do not appear to present an imminent and severe threat to public health. From a harm reduction perspective, these compounds may be good alternatives toMETH and MDMA. However, future work is needed to assess with certainty the long- term effects of amphetamine-type stimulants in humans.