Schizophrenia is one of our most common psychiatric diseases. It severely affects all aspects of psychological functions and results in loss of contact with reality. No cure exists and the treatments available today produce only partial relief for disease symptoms. The aim of this work is to better understand the etiology of schizophrenia by identification of candidate genes and gene pathways involved in the development of the disease. In a preliminarily study, the effects of medication and genetic factors were investigated in a candidate gene, serotonin 2C receptor. This study distinguished pharmacological effects, caused by neuroleptics, and/or genetic effects, caused by unique polymorphisms, from other effects responsible for mRNA expression changes on candidate genes. The core of the thesis describes a new candidate gene for schizophrenia, the quaking homolog, KH domain RNA binding (mouse) or QKI, located on chromosome 6q26-q27. The identification of QKI is supported by previous linkage studies, current association studies and mRNA expression studies using three different sample sets. The investigated samples included a 12-generation pedigree with 16 distantly related schizophrenic cases and their parents, 176 unrelated nuclear families with at least one affected child in each family and human brain autopsies from 55 schizophrenic cases and from 55 controls. Indirect evidence showing involvement of QKI in myelin regulation of central nervous system is presented. Myelin plays an important role in development of normal brains and disruption of QKI might lead to schizophrenia symptoms. In a forth sample set, including extended pedigrees originated from a geographically isolated area above the Arctic Circle, in northeast Sweden, two additional schizophrenia susceptibility loci were identified, 2q13 and 5q21. Both these regions have previously been highlighted as potential schizophrenia loci in several other investigations, including a large Finnish study. This suggests common schizophrenia susceptibility loci for Nordic populations. A pilot investigation including a genome wide haplotype analysis is presented. This statistical strategy could be further developed and applied to the artic Swedish families, including analysis of 900 microsatellites and 10,000 SNPs. These findings will facilitate the understanding of the schizophrenia etiology and may lead to development of more efficient treatments for patients that suffer from schizophrenia.

<p>MAL (myelin and lymphocyte protein), has been implicated in several malignancies including esophageal, gastric, and cervical cancers. We have demonstrated that the MAL protein is expressed in the normal breast epithelium, and aberrantly expressed in breast cancer. Bisulfite sequencing of the MAL promoter CpG island revealed hypermethylation in breast cancer cell lines and 69% of primary tumors analyzed compared with normal breast epithelial cells. Differential methylation between normal and cancer DNA was confined to the proximal promoter region. In a subset of breast cancer cell lines, promoter methylation correlated with transcriptional silencing that was reversible with the methylation inhibitor decitabine. Furthermore, exogenous expression of MAL in breast cancer cell lines resulted in decreased cell proliferation, motility, reduced cell invasion through Matrigel and suppressed anchorage-independent growth in soft agar. In a cohort of 122 primary breast tumors, immunohistochemical analysis revealed that the MAL protein was an independent predictor of benefit from adjuvant chemotherapy. Moreover, overexpression of MAL in triple-negative MDA-MB-468 and BT20 breast cancer cell lines was sufficient to confer sensitivity to epidermal growth factor receptor (EGFR)-tyrosine kinase inhibition and was associated with reduced phosphatidylinositol-3 kinase (PI3K)/Akt signaling. Immunohistochemistry studies conducted on 144 late-stage serous ovarian cancers showed that MAL expression was a significant predictor of survival. Knockdown of MAL expression in the SKOV8 ovarian cancer cell line reduced cell proliferation and resulted in increased sensitivity to the chemotherapeutic drug carboplatin. Thus, we have identified the MAL gene as a novel epigenetically regulated gene in breast cancer with implications for response to chemotherapy in both breast and ovarian cancer. Furthermore, we have shown that the MAL protein has predictive and prognostic value in breast and ovarian cancers, respectively.</p> / Dissertation

Transplantation of olfactory ensheathing cells (OECs) into injured spinal cord results in improved functional outcome through axonal regeneration, remyelination, and neuroprotection. However, because little is known of the fate of OECs transplanted into injured peripheral nerve, their myelin forming potential requires investigation. To study these issues OECs were isolated from the olfactory bulbs of adult green fluorescent protein (GFP)-expressing transgenic rats and transplanted into a sciatic nerve crush lesions. Five weeks to six months after transplantation the nerves were studied histologically and it was determined that GFP-expressing OECs survived in the lesion and distributed longitudinally across the lesion zone. Immunostaining revealed a high density of isoform Nav1.6 at the newly formed nodes of Ranvier which were flanked by paranodal Caspr staining. Immuno-electron microscopy for GFP revealed transplanted OECs form peripheral type myelin. These results indicate that transplanted OECs extensively integrate into transected peripheral nerve, form myelin on regenerated peripheral nerve fibers, and reconstruct nodes of Ranvier with proper sodium channel structure.

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No description available.

This thesis presents methods for quantitative MRI analysis of brain injury, repair and degeneration in multiple sclerosis (MS) that provide new insights into disease pathogenesis and evolution. / Demyelinated and inflammatory white-matter lesions are hallmark features of MS. A methodology is described to detect regions of acute white-matter lesions that undergo myelin destruction and repair based on analysis of magnetization transfer ratio (MTR) images. Validation is performed based on histopathology and error is assessed based on same-day scans. To quantify the spatial extent and temporal evolution of myelin destruction and repair, data from a 3-year clinical trial is analyzed using this method. Approximately 20% of acute lesion voxels show some repair over the initial 7 months. In subsequent months, there is little further repair, but some increases in the lesion volume undergoing demyelination. / Although less conspicuous on conventional MRI, there is considerable MS pathology in the brain tissue outside of white-matter lesions. An image-processing methodology was developed to obtain accurate metrics that quantify change over time in whole-brain MTR (associated with changes in myelin-density) and in T2 relaxation time (associated with changes in inflammatory edema). These metrics, in addition to metrics of brain atrophy and axonal integrity, were used to quantify brain injury and degeneration following immunoablation and autologous hematopoietic stem cell transplantation therapy for MS. Pronounced brain volume loss was detected immediately following therapy, associated with decreased myelin density and not resolution of edema. / Post-mortem histopathology has revealed abnormalities in the cortical grey-matter of MS patients that appear to be independent of white-matter lesions. A methodology to quantify neocortical injury and degeneration that yields cross-sectional and longitudinal metrics of cortical thickness and grey-matter/white-matter interface integrity both globally and regionally is presented and validated. MS patients with progressive disability showed greater decreases in cortical metrics compared to MS patients with stable disability. / The quantitative MRI analysis methods presented in this thesis are applicable to MRI data obtained in clinical trials of therapies for MS, have the necessary sensitivity and specificity to assess therapeutic efficacy, and provide new insights into disease pathogenesis and evolution.

Water is known to take on highly organized structures to influence the reactivity of chemical and biological systems; despite this, water is often only implicitly or approximately included in theoretical studies of biochemical systems, if not omitted entirely. Many of the current models for biological processes predate an understanding of the complex behaviour of water, yet these models have not been updated. This thesis presents an exploration of how a better of water might affect the models used to describe neurotransmission. Two classes of systems are investigated, representing the two main categories of neurotransmission: that which occurs along the length of a neuron, and that which occurs between one neuron and another cell. Lipid bilayers are studied using molecular dynamics, and neurotransmitters are studied using Car-Parrinello molecular dynamics. The results indicate that water structures may play a more specific role in neurotransmission than was previously thought.

Myelin basic protein (MBP) has fascinated researchers and clinicians alike due to its major structural role in myelin and the central nervous system, and its potent auto-immunogenic properties that cause demyelination in animal models. The charge variants of MBP have been of particular interest. The C1 component, the least modified and most cationic of the variants, is the most abundant form of MBP in healthy adult myelin. The C8 component, the most modified and the least cationic variant, has been found in higher proportions in myelin of MS patients and children. Here, an investigation of the structural differences between C1 and C8 components of MBP was conducted. The spectral and hydrodynamic properties of these variants were monitored via a number of biophysical/biochemical techniques. The effect of zinc (Zn2+) on the conformational behaviour of MBP was examined. Zn2+ is an abundant metal in the brain, and had been previously shown to induce hydrodynamic compaction in MBP. Both variants have a loose tertiary arrangement with subtle differences. This arrangement is deficient in secondary structure and undergoes non-cooperative temperature-induced melting. Zn2+ stabilizes a molten globular-like state with enhanced ANS fluorescence, and promotes oligomerization.

[Truncated abstract] Olfactory ensheathing glia (OEG) have been demonstrated to improve functional and anatomical outcomes after injury to the nervous system and are currently being trialled clinically. This thesis presents the investigation of two important issues in OEG biology. The first study (Chapter 2) investigates effects of different members of the neuregulin (NRG) family of molecules on the proliferation of OEG, as a means of quickly obtaining large numbers of cells for clinical or experimental use. We report that NRG-1β, but not NRG- 2α or NRG-3, has a significant proliferative effect. Furthermore, we report for the first time that use of different mitogens (forskolin and pituitary extract) commonly used to expand these cells in vitro, can have a significant effect on the responsiveness of OEG to added NRG in subsequent mitogenic assays. OEG grown initially with forskolin and pituitary extract exhibited increased basal proliferation rates in comparison to OEG originally expanded without these factors, and this increased rate of proliferation was sustained for at least 6 days following their withdrawal from the culture medium. We also report for the first time the expression pattern of ErbB2, ErbB3 and ErbB4 receptors on p75-selected OEG, and investigate their contribution to the NRG mitogenic effect by the use of inhibitory ErbB antibodies. Our second study (Chapter 3) seeks to clarify the role of OEG in promoting myelination of central nervous system neurons. In this study we have investigated the myelinating ability of OEG derived from embryonic (EEG), postnatal (PEG) and adult tissue (AEG) both in vitro and in vivo. OEG selected by p75-immunopanning were co-cultured with dissociated cultures of TrkA-dependant embryonic dorsal root ganglion (DRG) neurons. EEG, but not AEG or PEG, successfully myelinated DRG neurons in the presence of serum and/or ascorbate. AEG also failed to myelinate GDNF-dependant embryonic DRG cultures, and growth factor-independent adult DRG cultures. Transplantation of OEG into lysolecithin demyelinated spinal cord demonstrated distinct ultrastructural differences between transplants of OEG derived from animals of different ages. Furthermore, we demonstrate that clearance of degraded myelin from the lesion site appears to be more effective when animals are transplanted with EEG rather than AEG or Schwann cell preparations. These results suggest that myelinating potential of OEG in vitro and behaviour of these cells following transplantation in vivo are developmentally regulated.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 4 uppsatser.