The Whitehall II (Stress and Health) study is a prospective study based on originally 10,308 British civil servants. Since 1985, rich socio-demographic, health and life-style measures have been acquired every 2-5 years. Eight hundred participants were randomly selected from the remaining 6,308 participants of Phase 11 for magnetic resonance imaging (MRI) and further examination in Oxford (2012-14). There is evidence of changes in brain anatomy and mental health following traumatic events, such as combat stress or sexual abuse, in patients with posttraumatic stress disorder, mood or personality disorders, but little is known about the association between everyday stress, brain structure and function, and mental health in the general population. The secondary stress markers, Allostatic Load (AL) index, Framingham Stroke Risk score (FSRS) and Metabolic Syndrome (MetS) were selected as potential predictors of brain changes at follow-up. This thesis focuses on measures of structural grey and white matter (GM, WM) integrity, collected with the Siemens 3T Verio scanner in the first 563 participants of the Oxford study. As hypothesised, stress markers measured as early as 20 years prior to the scan, predicted lower GM and WM integrity in older age. Unique linear relationships remained even after controlling for socio-demographic confounders between each stress marker and GM density but not with measures of WM integrity. This suggests that some, if not most variance is shared between the stress markers and the usual correlates of general health, such as age and employment class. The three markers did not have equal power to predict brain measures: AL added more unique predictive variance to GM density than MetS and FSRS. On the other hand, FSRS was the more powerful predictor of poor WM integrity compared with AL and MetS, and after removing confounding variable effects. This thesis thus provides some empirical support for the concept of allostatic load, linking 'everyday' stress and features of the ageing human brain.

Morphological studies have shown pathology of neurons and glia in many brain disorders, including psychiatric disorders such as major depression. However, most biochemical characterizations of postmortem human brain tissue have not made a distinction between neurons and glia. Laser capture microdissection (LCM) to isolate specific cell types has the potential to advance our understanding of human brain pathologies. Here, RT-PCR was used to evaluate the utility of LCM in the capture of noradrenergic neurons, astrocytes and oligodendrocytes from the locus coeruleus (LC) of postmortem human brain. The 3 LC cell types were individually identified using modifications of established histological and morphological methods. LCM settings were optimized for each cell type and captured cell bodies were those having no nearby cell body of a different phenotype. LC neurons (200), astrocytes (500), and oligodendrocytes (500) were captured within the LC from 3 postmortem brains. RNA was isolated, reversed transcribed, and markers for neurons (tyrosine hydroxylase [TH], dopamine beta-hydroxylase [DBH]), astrocytes (glial fibrillary acidic protein [GFAP]), and oligodendrocytes (myelin oligodendrocyte glycoprotein [MOG]), along with 3 references (actin, GAPDH, ubiquitin C) were PCR amplified and quantified by standardized end-point PCR. RNA quality as assessed by RIN was not altered by LCM as compared to RNA isolated from homogenized tissue. TH gene expression was found only in neurons in 2 of the 3 brains. DBH gene expression was ~5-fold greater in neurons than in astrocytes and oligodendrocytes. GFAP gene expression in astrocytes was 7- and 5-fold greater than that in neurons and oligodendrocytes, respectively. MOG gene expression was only detected in oligodendrocytes. Different expression ratios of marker genes between neurons and glia suggest that simple cross contamination of mRNA is unlikely. Glial cells may contain DBH mRNA. Alternatively, DBH, but not TH, mRNA may occur in neuronal dendrites or axons in close association with glial cells that become captured with glia during LCM. GFAP may be expressed in low levels in neurons and oligodendrocytes, or alternatively, GFAP mRNA may be located in astrocytic processes in close association with neuronal and oligodendrocyte cell bodies. Use of a single marker to identify a cell type may be insufficient; other cell types for comparison or additional markers may be required. Multiple well-characterized markers can be used to evaluate clarity of cell capture for each sample. With due regard for specific limitations, LCM can be used to evaluate the molecular pathology of specific cell types in postmortem human brain.

This study investigated the functional significance of cerebral asymmetries. Width measurements of the human brain were derived from computerized tomographic (CT) films and related to intellectual variables as determined by the Wechsler Adult Intelligence Scale Revised (WAIS-R). Subjects were adults of both sexes who had been referred for neurologic examination and were diagnosed as having no abnormalities (N=28). Reasons for referral included headache, dizziness, or to rule out central nervous system damage following various types of trauma. The asymmetry of hemispheric widths (left minus right) in the frontal, temporoparietal, and occipital areas was correlated with Verbal IQ minus Performance IQ scores within subjects. The difference between verbal and performance IQ scores was used because it reflected an IQ imbalance (IQ-I). Correlations obtained were -.30, -.26, and .06 (respectively). None of these correlations were significant by means of a two-tailed test. There were relationships between particular width asymmetries and individual subtest scores (p≤.05). The Verbal 1 (V1) subtest (Information) was correlated -.50, -.39 and -.47 with brain width asymmetries at 25%, 33% and 50% of the AP distance respectively. V1 correlated .39 with width asymmetry at 80%. Verbal 3 (Vocabulary), verbal 4 (Arithmetic) and verbal 5 (Comprehension) correlated .53 .38, and .39 with width asymmetry at 60% of the AP distance. Performance 1 (Picture Completion) correlated .46 with the width asymmetry at 20% of the AP length. In summary, there does appear to be some specific correlation between individual variation in brain asymmetry and cognitive processing. Relative size of the area of the brain that is involved in a key aspect of a particular cognitive processing may be a factor in the effectiveness of that processing. Further research appears warranted to confirm and clarify a possible relation between anatomical asymmetry and patterns of intellectual ability.

Viral infection severity often varies with host factors such as age and sex. The pathogenesis of infections caused by a broad range of viruses, from neurotropic viruses like Rabies and Zika to respiratory viruses such as Influenza and SARS-CoV-2, differ between the sexes and across the lifespan. Typically, older males are more susceptible to severe acute outcomes, while females are more vulnerable to the post-acute sequelae of infections. All of these complications can include neuroinflammation, stroke, cognitive dysfunction, and delirium. While these symptoms can be secondary to infection, recent studies suggest that even peripheral infections can lead to neuropathological changes in the brain. However, few studies have characterized the expression of viral receptors in the human brain or examined age- or sex-related differences in such expression. In this study, we used a publicly accessible transcriptomic database to assess the impact of age and sex on the expression of 67 viral host factor genes, associated with ten virus families. Analyzing data from 15 brain areas (n=33, F=14, M=19, age:4 mo-80 yrs), we determined the lifespan trajectory for each gene in each area via LOESS regressions. We used unsupervised hierarchical clustering to determine if a brain-wide pattern or virus family pattern can be detected. Using Dense-tSNE, a dimension-reduction and visualization technique, we discovered four distinct developmental trajectories, clustering the areas into two mixed-sex subcortical clusters and one each of male and female cortical clusters. Applying Differential Expression Sliding Window Analysis (DeSWAN), we identified the genes driving these age- and sex-related differences. Many sex differences were noted in childhood, potentially impacting the brain's susceptibility to viral infections and underscoring a broader dimorphic organization of male and female brains. These insights contribute to our understanding of sex-specific responses to viral infections, offering the potential for more personalized treatment strategies. / Thesis / Master of Science (MSc) / Viral infections, like Influenza and SARS-CoV-2, vary in severity based on a person's age and sex. Generally, older men suffer severe immediate symptoms such as stroke and seizures, while women endure long-term effects, including brain inflammation and cognitive issues. Recent research suggests even non-brain-related infections can lead to changes within the brain. Yet, our understanding of how our brains' viral receptors - key to infection - change with age and between sexes is limited. We used a public database to explore these changes, studying receptor-related genes in different brain areas across various ages and sexes. Our analysis revealed unique patterns of gene expression, grouping the brain into different regions based on development and sex. We noticed many differences between men and women during childhood, potentially influencing how their brains respond to viruses. This research aids our understanding of why viral infections impact individuals differently based on age and sex, offering insights that could help develop personalized treatments.

Neural stem/progenitor cells (NSPCs) play a crucial part in the evolutionary development of the human neocortex. During early postnatal development, NSPCs give rise to immature neurons called neuroblasts within the subventricular zone (SVZ) that utilize unique migratory streams to integrate widely in the cerebral cortex. However, the cellular mechanisms enabling these unique migratory routes through the compacted cellular landscape remain unknown. Special emphasis has been placed on understanding the susceptibility of these brain regions to severe conditions such as congenital heart disease (CHD), resulting in poor neurological outcomes. Owing to its reminiscent complexity to humans, the neonatal piglet (Sus scrofa domesticus), which possesses a highly evolved gyrencephalic neocortex and an expansive outer SVZ, provides a powerful translational model system for the study of how heart dysfunction impacts cortical development from both a modern and evolutionary perspective. The present study provides a detailed characterization of neuroblast migration along their associate substrates in the piglet cortex under normal physiological conditions and how reduced oxygenation (i.e., hypoxia) can impact their vulnerability and/or resistance to injury during a critical period of postnatal development. In this thesis, I investigated the spatiotemporal distribution and developmental origin of SVZ-derived neuroblasts. Following BrdU tracing, multiplex labeling, and confocal microscopy, I show that the porcine brain contains populations of newly generated (BrdU+/DCX+) neurons in the prefrontal cortex that are produced postnatally. Regional analyses using immunohistochemical staining for doublecortin (DCX), a marker expressed by immature neurons, revealed that DCX+ clusters co-express markers of neuronal cell migration (PSA-NCAM), GABAergic interneuron marker (GABA+), and specific transcription factors (SCGN+SP8+) associated with the caudal- and lateral ganglionic eminence progenitor domains in the ventral forebrain. Moreover, I found that DCX+ neuroblasts are encased by astrocytic processes and tightly associated with blood vessels in the SVZ. Additionally, this thesis describes the use of chronic hypoxia as a model to profile neuroblast migration along associated substrates in pathological conditions related to CHD. Together, this work serves as a framework for the functional utilization of the neonatal piglet to understand the impact of substrate-dependent neuronal migration on brain maturation and neurodevelopmental diseases. / Doctor of Philosophy / Congenital heart disease (CHD) remains a significant cause of abnormal fetal brain development, affecting 1-2% of live births per year. Although many surgical strategies have shown promise in increasing quality of life, the current challenges remain the long-term cognitive deficits and diverse neurodevelopmental disabilities due to CHD. Recent studies suggest that dysregulated neurogenesis, which is associated with impaired neocortical development in human fetuses of CHD, may be influenced by altered brain circulation of blood and oxygen deliverance during critical periods of prenatal cortical growth. The brain's subventricular zone (SVZ) niche is essential for producing new neurons following birth to restore, repair, and replace existing neurons in the developing brain. In addition, these newborn neurons undergo long-distance migration from the SVZ to reach their final cortical destinations and ultimately contribute to brain development/plasticity. This study seeks to characterize the migration patterns of newborn neurons and the substrates (e.g., blood vessels or astrocytes), enabling the movement along the unique migratory routes under normal and pathological (i.e., hypoxia) conditions. In short, we found that the vast majority of the SVZ-derived newborn neurons are inhibitory neurons (i.e., interneurons) that originate in the deep region of the brain called the telencephalon and migrate tangentially utilizing blood vessels as scaffolds to the cortex, which is likely to contribute to cortical plasticity. These postnatal piglet findings demonstrate that swine represent a powerful translational model system to study large-brained mammalian cortical development and neuronal migration as it correlates to humans in normal and diseased states.

Agonist-stimulated phosphoinositide (PPI) hydrolysis is a major signal transduction pathway in brain. These studies investigated neurotransmitter stimulated PPI hydrolysis in postmortem human brain. Preliminary studies using rat brain suggested that moderate postmortem delay has little effect on PPI hydrolysis and that human tissue might be reliably studied for differences in receptor-PLC coupling. Studies in human brain membranes (frontal cortex) indicated that the time course for GTPγS and carbachol/GTPγS-stimulated PPI hydrolysis was linear for at least 20 min. GTPγS-stimulated [3H] inositol phosphate (InsP) formation was enhanced by carbachol (232%) and 5-Hydroxytryptamine (5HT - 147%). SAX-HPLC seperation of [3H] inositol polyphosphates indicated that the major isomer of inositol trisphosphate (InsP3) was Ins(1,4,5)P3, the expected product of PtdIns(4,5)P2 hydrolysis. Ca2+ increased PPI hydrolysis progressively from 100 nM through 50 μM and synergistically enhanced carbachol/GTPγS stimulation. Comparisons of age-matched controls with Alzheimer's patients indicated that GTPγS, carbachol/GTPγS, and 5HT/GTPγS-stimulation of PPI hydrolysis is reduced approximately 50% in membranes prepared from Alzheimer's patients. Ca2+ stimulation of PPI hydrolysis was not different between controls and Alzheimer's patients suggesting that muscarinic cholinergic and serotonergic receptors are uncoupled from PLC in Alzheimer's disease. These studies indicate that there are changes in cholinergic and serotonergic signal transduction in Alzheimer's disease. Further, this method can be used to study signal transduction events in postmortem human brain.

Mathematical models are used to estimate physiological parameters which are otherwise inaccessible to measurement. When applied to tracer kinetic data obtained in positron tomographic studies, these methods allow for the quantitative analysis of regional metabolic rates in the human brain during life. Dopamine, a neurotransmitter in the mammalian central nervous system, is synthesized by the action of aromatic amino acid decarboxylase on L-dihydroxyphenylalanine (L-dopa). A fluorinated analogue of L-dopa, 6-[18F]fluoro-L-dopa, is used as a tracer in positron tomography to study the nigrostriatal dopaminergic system. Although this tracer has been in use in man for over ten years, a definitive method of quantitative analysis has not yet emerged. The comparison of quantitative results obtained by this approach has been confounded by the diversity of mathematical modelling techniques employed. These techniques range from simple graphical analyses, which yield a single rate constant for the entire system, to complex compartmental approaches, which may not present a unique solution. The goal of this research has been to develop an approach to quantitative analysis which is both informative and mathematically justifiable. Compartmental models of increasing complexity have been evaluated by statistical methods (F-test) to determine the simplest model which adequately fits the data. This strict methodological approach indicates that a two-compartment, three-parameter model produces the best fit, in a statistical sense, to the measured data. This data has also been analyzed by a simple graphical method to yield an influx constant for the system. The influx constant has also been calculated, for comparison, from the results of the compartmental analysis. The two methods were found to be in excellent agreement; both responded predictably to physiological perturbations of the system. While the compartmental method yielded a more informative analysis of the system, the graphically determined influx constant was found to be less sensitive to measurement errors. It is recommended that these two methods be applied in parallel, such that the comparison of results may serve as an internal measure of the integrity of the analysis. / Thesis / Master of Science (MS)

Οι όγκοι εγκεφάλου αποτελούν μια ομάδα όγκων με ιδιαίτερα χαρακτηριστικά. Η ογκογένεση έχει συσχετισθεί σε αρκετούς όγκους, ανάμεσά τους και ορισμένοι όγκοι εγκεφάλου, με την πρωτείνη θερμικού σοκ 90 (Hsp90). Σε πρόσφατες μελέτες, έχει αποδειχθεί η η συμμετοχή της Hsp90 στην αποδόμηση της ογκοκατασταλτικής πρωτείνης pVHL, η οποία είναι απαραίτητητη για την αποδόμηση του μεταγραφικού παράγοντα που ενεργοποιείται στην υποξία (HIF-1α). Επιπλέον, έχει βρεθεί πως οι ανταγωνιστές της Hsp90 μειώνουν τα επίπεδα έκφρασης του VEGFR-3. Στόχος της παρούσας μελέτης ήταν η εκτίμηση των επιπέδων έκφρασης των μορίων Hsp90, pVHL, HIF-1α και VEGFR-3 στους όγκους εγκεφάλου και οι πιθανές συσχετίσεις μεταξύ τους. Εξετάσθηκαν συνολικά 89 óγκοι εγκεφάλου με την ανοσοϊστοχημική μέθοδο. Στους αστροκυτταρικούς όγκους, η Ηsp90 φαίνεται πως οδηγεί στη σταθεροποίηση του HIF-1α μέσω της σύνδεσής της με τη pVHL. Στα μυελοβλαστώματα από την άλλη, ο HIF-1α ρυθμίζεται από τη Hsp90 με τρόπο ανεξάρτητο από τη pVHL. Βρέθηκε συσχέτιση της έκφρασης του VEGFR-3 με τη Hsp90 αλλά και τον HIF-1α σε ομάδα όγκων του εγκεφάλου, η βιολογική συμπεριφορά των οποίων θα πρέπει να διερευνηθεί. / Brain tumors constitute a special group of tumors. In many tumors, including brain tumors, tumorigenesis has been associated with heat shock protein 90 (Hsp90). ). Recent studies have demonstrated that Hsp90 is essential for the degradation of tumor suppressor protein, pVHL, which is essential for the degradation of Hypoxia Induced Factor 1α (HIF-1α). In addition,it has been proved that Hsp90 antagonists, reduce the expression VEGFR-3. the aim of the current study was to estimate the levels of expression of Hsp90, pVHL, HIF-1α and VEGFR-3 in brain tumors and the possible correlations among them.89 human brain tumors were studied immunohistochemically. In astrocytic tumors, Hsp90 seems to stabilize HIF-1α, through binding to pVHL. On the other hand, in medulloblastomas, HIF-1α seems to be regulated by Hsp90, in a way that seems to be independent from pVHL. We found a correlation between the expression of VEGFR-3 and Hsp90 and HIF-1α in a group of brain tumors, the biological behavior of which must be studied.

Traditional fMRI utilizes blood oxygenation level dependent (BOLD) contrast to map brain activity. BOLD signal is sensitive to the hemodynamic changes associated with brain activity, and gives an indirect measure of brain activity. Low frequency fluctuations (LFFs) have been observed in the BOLD signal even in the absence of any anesthetic agent, and the correlations between the fluctuations from different brain regions has been used to map functional connectivity in the brain. Most studies involving spontaneous fluctuations in the BOLD signal extract connectivity patterns that show relationships between brain areas that are maintained over the length of the scanning session. The research presented in this document investigates the spatiotemporal dynamics of the BOLD fluctuations to identify common spatiotemporal patterns within a scan. First, the presence of a visually detectable spatiotemporal propagation pattern is demonstrated by utilizing single-slice data with high spatial and temporal resolution. The pattern consists of lateral-medial propagation of BOLD signal, demonstrating the presence of time-varying features in spontaneous BOLD fluctuations. Further, a novel pattern finding algorithm is developed for detecting repeated spatiotemporal patterns in BOLD fMRI data. The algorithm is applied to high temporal resolution T2*-weighted multislice images obtained from rats and humans in the absence of any task or stimulation. In rats, the primary pattern consists of waves of high signal intensity, propagating in a lateral-medial direction across the cortex, replicating the results obtained using visual observation. In humans, the most common spatiotemporal pattern consisted of an alteration between activation of areas comprising the "default-mode" (e.g., posterior cingulate and anterior medial prefrontal cortices) and the "task-positive" (e.g., superior parietal and premotor cortices) networks. Signal propagation from focal starting points is also observed. The pattern finding algorithm is shown to be reasonably insensitive to the variation in user-defined parameters, and the results are consistent within and between subjects. This novel approach for probing the spontaneous network activity of the brain has implications for the interpretation of conventional functional connectivity studies, and may increase the amount of information that can be obtained from neuroimaging data.

Ovarian steroid hormones are known to produce several different effects in the brain. In addition to their role in gonadotropin release, ovulation and sexual behaviour they also seem to affect mood and emotions, as shown in women with the premenstrual tension syndrome. Some steroids have the ability to affect brain excitability. Estradiol decreases the electroshock threshold while progesterone acts as an anti-convulsant and anaesthetic in both animals and humans. Several earlier studies have shown a specific uptake of several steroids in the animal brain but only a few recent studies have established the presence of steroids in the human brain. In the present studies, the dissections of rat and human brains were carried out macroscopically and areas that are considered to be related to steroid effects were chosen. Steroid concentrations were measured by radioimmunoassay after extraction and separation with celite chromatography. The accuracy and specificity of these methods were estimated. In the animal studies, immature female rats were treated with Pregnant Mare's Serum Gonadotropin (PMSG) to induce simultaneous ovulations. Concentrations of estradiol and progesterone were measured in seven brain areas pre- and postovulatory. The highest concentration of estradiol, pre- and postovulatory, was found in the hypothalamus and differences between the two cycle phases were detected in most brain areas. The preovulatory concentrations of progesterone were low and the highest postovulatory concentration was found in the cerebral cortex. In one study, the rats were injected with pharmacological doses of progesterone to induce "anaesthesia". High uptake of progesterone was found and a regional variation in the formation of 5&lt;*-pregnane-3,20-dione in the brain with the highest ratio in the medulla oblongata. Concentrations of progesterone, 5a-pregnane-3*20-dione, estradiol and testosterone were determined in 17 brain areas of fertile compared to postmenopausal women. All steroids displayed regional differences in brain concentrations. Higher concentrations of estradiol and progesterone were found in the fertile compared to the postmenopausal women. In summary, these studies show that the concentrations of ovarian steroids in the brain are different at different endocrine states in both rats and humans and that there are regional differences in brain steroid distribution. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1987, härtill 5 uppsastser</p> / digitalisering@umu