Immune response to insulin and changes in the gut immune system in children with or at risk for type 1 diabetes

Type 1 diabetes (T1D) is considered to be an autoimmune disease. The cause of T1D is the destruction of insulin-producing β-cells in the pancreatic islets. The autoimmune nature of T1D is characterized by the presence of autoreactive T-cells and autoantibodies against β-cell molecules. Insulin is the only β-cell-specific autoantigen associated with T1D but the insulin autoantibodies (IAAs) are difficult to measure with proper sensitivity. T-cell assays for detection of autoreactive T-cells, such as insulin-specific T-cells, have also proven to be difficult to perform. The genetic risk of T1D is associated with the HLA gene region but the environmental factors also play an important role. The most studied environmental risk factors of T1D are enteroviruses and cow's milk which both affect the immune system through the gut. One hypothesis is that the insulin-specific immune response develops against bovine insulin in cow's milk during early infancy and later spreads to include human insulin. The aims of this study were to determine whether the separation of immunoglobulin (Ig)G from plasma would improve the sensitivity of the IAA assay and how insulin treatment affects the cellular immune response to insulin in newly diagnosed patients. Furthermore, the effect of insulin concentration in mother's breast milk on the development of antibodies to dietary insulin in the child was examined. Small intestinal biopsies were also obtained from children with T1D to characterize any immunological changes associated with T1D in the gut. The isolation of the IgG fraction from the plasma of T1D patients negative for plasma IAA led to detectable IAA levels that exceeded those in the control children. Thus the isolation of IgG may improve the sensitivity of the IAA assay. The effect of insulin treatment on insulin-specific T-cells was studied by culturing peripheral blood mononuclear cells with insulin. The insulin stimulation induced increased expression of regulatory T-cell markers, such as Foxp3, in those patients treated with insulin than in patients examined before initiating insulin treatment. This finding suggests that insulin treatment in patients with T1D stimulates regulatory T-cells in vivo and this may partly explain the difficulties in measuring autoantigen-specific T-cell responses in recently diagnosed patients. The stimulation of regulatory T-cells by insulin treatment may also explain the remission period often seen after initiating insulin treatment. In the third study we showed that insulin concentration in mother's breast milk correlates inversely with the levels of bovine insulin-specific antibodies in those infants who were exposed to cow's milk proteins in their diet, suggesting that human insulin in breast milk induces tolerance to dietary bovine insulin. However, in infants who later developed T1D-associated autoantibodies, the insulin concentration in their mother's breast milk was increased. This finding may indicate that in those children prone to β-cell autoimmunity, breast milk insulin does not promote tolerance to insulin. In the small intestinal biopsies the presence of several immunological markers were quantified with the RT-PCR. From these markers the expression of the interleukin (IL)-18 cytokine was significantly increased in the gut in patients with T1D compared with children with celiac disease or control children. The increased IL-18 expression lends further support for the hypothesis that the gut immune system is involved in the pathogenesis of T1D.

Effects of oxygen provision on the physiology of baker's yeast Saccharomyces cerevisiae

The availability of oxygen has a major effect on all organisms. The yeast Saccharomyces cerevisiae is able to adapt its metabolism for growth in different conditions of oxygen provision, and to grow even under complete lack of oxygen. Although the physiology of S. cerevisiae has mainly been studied under fully aerobic and anaerobic conditions, less is known of metabolism under oxygen-limited conditions and of the adaptation to changing conditions of oxygen provision. This study compared the physiology of S. cerevisiae in conditions of five levels of oxygen provision (0, 0.5, 1.0, 2.8 and 20.9% O2 in feed gas) by using measurements on metabolite, transcriptome and proteome levels. On the transcriptional level, the main differences were observed between the three level groups, 0, 0.5 2.8 and 20.9% O2 which led to fully fermentative, respiro-fermentative and fully respiratory modes of metabolism, respectively. However, proteome analysis suggested post-transcriptional regulation at the level of 0.5 O2. The analysis of metabolite and transcript levels of central carbon metabolism also suggested post-transcriptional regulation especially in glycolysis. Further, a global upregulation of genes related to respiratory pathways was observed in the oxygen-limited conditions and the same trend was seen in the proteome analysis and in the activities of enzymes of the TCA cycle. The responses of intracellular metabolites related to central carbon metabolism and transcriptional responses to change in oxygen availability were studied. As a response to sudden oxygen depletion, concentrations of the metabolites of central carbon metabolism responded faster than the corresponding levels of gene expression. In general, the genome-wide transcriptional responses to oxygen depletion were highly similar when two different initial conditions of oxygen provision (20.9 and 1.0% O2) were compared. The genes related to growth and cell proliferation were transiently downregulated whereas the genes related to protein degradation and phosphate uptake were transiently upregulated. In the cultures initially receiving 1.0% O2, a transient upregulation of genes related to fatty acid oxidation, peroxisomal biogenesis, response to oxidative stress and pentose phosphate pathway was observed. Additionally, this work analysed the effect of oxygen on transcription of genes belonging to the hexose transporter gene family. Although the specific glucose uptake rate was highest in fully anaerobic conditions, none of the hxt genes showed highest expression in anaerobic conditions. However, the expression of genes encoding the moderately low affinity transporters decreased with the decreasing oxygen level. Thus it was concluded that there is a relative increase in high affinity transport in anaerobic conditions supporting the high uptake rate.

Microbe-induced activation of inflammatory cytokine response in human cells

Human body is in continuous contact with microbes. Although many microbes are harmless or beneficial for humans, pathogenic microbes possess a threat to wellbeing. Antimicrobial protection is provided by the immune system, which can be functionally divided into two parts, namely innate and adaptive immunity. The key players of the innate immunity are phagocytic white blood cells such as neutrophils, monocytes, macrophages and dendritic cells (DCs), which constantly monitor the blood and peripheral tissues. These cells are armed for rapid activation upon microbial contact since they express a variety of microbe-recognizing receptors. Macrophages and DCs also act as antigen presenting cells (APCs) and play an important role in the development of adaptive immunity. The development of adaptive immunity requires intimate cooperation between APCs and T lymphocytes and results in microbe-specific immune responses. Moreover, adaptive immunity generates immunological memory, which rapidly and efficiently protects the host from reinfection. Properly functioning immune system requires efficient communication between cells. Cytokines are proteins, which mediate intercellular communication together with direct cell-cell contacts. Immune cells produce inflammatory cytokines rapidly following microbial contact. Inflammatory cytokines modulate the development of local immune response by binding to cell surface receptors, which results in the activation of intracellular signalling and modulates target cell gene expression. One class of inflammatory cytokines chemokines has a major role in regulating cellular traffic. Locally produced inflammatory chemokines guide the recruitment of effector cells to the site of inflammation during microbial infection. In this study two key questions were addressed. First, the ability of pathogenic and non-pathogenic Gram-positive bacteria to activate inflammatory cytokine and chemokine production in different human APCs was compared. In these studies macrophages and DCs were stimulated with pathogenic Steptococcus pyogenes or non-pathogenic Lactobacillus rhamnosus. The second aim of this thesis work was to analyze the role of pro-inflammatory cytokines in the regulation of microbe-induced chemokine production. In these studies bacteria-stimulated macrophages and influenza A virus-infected lung epithelial cells were used as model systems. The results of this study show that although macrophages and DCs share several common antimicrobial functions, these cells have significantly distinct responses against pathogenic and non-pathogenic Gram-positive bacteria. Macrophages were activated in a nearly similar fashion by pathogenic S. pyogenes and non-pathogenic L. rhamnosus. Both bacteria induced the production of similar core set of inflammatory chemokines consisting of several CC-class chemokines and CXCL8. These chemokines attract monocytes, neutrophils, dendritic cells and T cells. Thus, the results suggest that bacteria-activated macrophages efficiently recruit other effector cells to the site of inflammation. Moreover, macrophages seem to be activated by all bacteria irrespective of their pathogenicity. DCs, in contrast, were efficiently activated only by pathogenic S. pyogenes, which induced DC maturation and production of several inflammatory cytokines and chemokines. In contrast, L. rhamnosus-stimulated DCs matured only partially and, most importantly, these cells did not produce inflammatory cytokines or chemokines. L. rhamnosus-stimulated DCs had a phenotype of "semi-mature" DCs and this type of DCs have been suggested to enhance tolerogenic adaptive immune responses. Since DCs have an essential role in the development of adaptive immune response the results suggest that, in contrast to macrophages, DCs may be able to discriminate between pathogenic and non-pathogenic bacteria and thus mount appropriate inflammatory or tolerogenic adaptive immune response depending on the microbe in question. The results of this study also show that pro-inflammatory cytokines can contribute to microbe-induced chemokine production at multiple levels. S. pyogenes-induced type I interferon (IFN) was found to enhance the production of certain inflammatory chemokines in macrophages during bacterial stimulation. Thus, bacteria-induced chemokine production is regulated by direct (microbe-induced) and indirect (pro-inflammatory cytokine-induced) mechanisms during inflammation. In epithelial cells IFN- and tumor necrosis factor- (TNF-) were found to enhance the expression of PRRs and components of cellular signal transduction machinery. Pre-treatment of epithelial cells with these cytokines prior to virus infection resulted in markedly enhanced chemokine response compared to untreated cells. In conclusion, the results obtained from this study show that pro-inflammatory cytokines can enhance microbe-induced chemokine production during microbial infection by providing a positive feedback loop. In addition, pro-inflammatory cytokines can render normally low-responding cells to high chemokine producers via enhancement of microbial detection and signal transduction.

Ozone-induced signaling in Arabidopsis thaliana

Tropospheric ozone (O3) is one of the most common air pollutants in industrialized countries, and an increasing problem in rapidly industrialising and developing countries in Asia, Africa and South America. Elevated concentrations of tropospheric O3 can lead to decrease in photosynthesis rate and therefore affect the normal metabolism, growth and seed production. Acute and high O3 episodes can lead to extensive damage leading to dead tissue in plants. Thus, O3 derived growth defects can lead to reduction in crop yield thereby leading to economical losses. Despite the extensive research on this area, many questions remain open on how these processes are controlled. In this study, the stress-induced signaling routes and the components involved were elucidated in more detail starting from visual damage to changes in gene expression, signaling routes and plant hormone interactions that are involved in O3-induced cell death. In order to elucidate O3-induced responses in Arabidopsis, mitogen-activated protein kinase (MAPK) signaling was studied using different hormonal signaling mutants. MAPKs were activated at the beginning of the O3 exposure. The activity of MAPKs, which were identified as AtMPK3 and AtMPK6, reached the maximum at 1 and 2 hours after the start of the exposure, respectively. The activity decreased back to clean air levels at 8 hours after the start of the exposure. Both AtMPK3 and AtMPK6 were translocated to nucleus at the beginning of the O3 exposure where they most likely affect gene expression. Differences were seen between different hormonal signaling mutants. Functional SA signaling was shown to be needed for the full protein levels and activation of AtMPK3. In addition, AtMPK3 and AtMPK6 activation was not dependent on ethylene signaling. Finally, jasmonic acid was also shown to have an impact on AtMPK3 protein levels and AtMPK3 activity. To further study O3-induced cell death, an earlier isolated O3 sensitive Arabidopsis mutant rcd1 was mapped, cloned and further characterized. RCD1 was shown to encode a gene with WWE and ADP-ribosylation domains known to be involved in protein-protein interactions and cell signaling. rcd1 was shown to be involved in many processes including hormonal signaling and regulation of stress-responsive genes. rcd1 is sensitive against O3 and apoplastic superoxide, but tolerant against paraquat that produces superoxide in chloroplast. rcd1 is also partially insensitive to glucose and has alterations in hormone responses. These alterations are seen as ABA insensitivity, reduced jasmonic acid sensitivity and reduced ethylene sensitivity. All these features suggest that RCD1 acts as an integrative node in hormonal signaling and it is involved in the hormonal regulation of several specific stress-responsive genes. Further studies with the rcd1 mutant showed that it exhibits the classical features of programmed cell death, PCD, in response to O3. These include nuclear shrinkage, chromatin condensation, nuclear DNA degradation, cytosol vesiculation and accumulation of phenolic compounds and eventually patches of HR-like lesions. rcd1 was found to produce extensive amount of salicylic acid and jasmonic acid in response to O3. Double mutant studies showed that SA independent and dependent processes were involved in the O3-induced PCD in rcd1 and that increased sensitivity against JA led to increased sensitivity against O3. Furthermore, rcd1 had alterations in MAPK signature that resembled changes that were previously seen in mutants defective in SA and JA signaling. Nitric oxide accumulation and its impact on O3-induced cell death were also studied. Transient accumulation of NO was seen at the beginning of the O3 exposure, and during late time points, NO accumulation coincided with the HR-like lesions. NO was shown to modify defense gene expression, such as, SA and ethylene biosynthetic genes. Furthermore, rcd1 was shown to produce more NO in control conditions. In conclusion, NO was shown to be involved in O3-induced signaling leading to attenuation of SA biosynthesis and other defense related genes.

Plant guard cell anion channel SLAC1 regulates stomatal closure

Plants are rooted to their growth place; therefore it is important that they react adequately to changes in environmental conditions. Stomatal pores, which are formed of a pair of guard cells in leaf epidermis, regulate plant gas-exchange. Importantly, guard cells protect the plant from desiccation in drought conditions by reducing the aperture of the stomatal pore. They serve also as the first barrier against the major air pollutant ozone, but the behaviour of guard cells during ozone exposure has not been sufficiently addressed. Aperture of the stomatal pore is regulated by the influx and efflux of osmotically active ions via ion channels and transporters across the guard cell membrane, however the molecular identity of guard cell plasma membrane anion channel has remained unknown. In the frame of this study, guard cell behaviour during ozone exposure was studied using the newly constructed Arabidopsis whole-rosette gas-exchange system. Ozone induced a Rapid Transient Decrease (RTD) in stomatal conductance within 10 min from the start of exposure, which was followed by a recovery in the conductance within the next 40 min. The decrease in stomatal conductance was dependent on the applied ozone concentration. Three minutes of ozone exposure was sufficient to induce RTD and further ozone application during the closure-recovery process had no effect on RTD, demonstrating that the whole process is programmed within the first three minutes. To address the molecular components responsible for RTD, the ozone response was measured in 59 different Arabidopsis mutants involved in guard cell signalling. Four of the tested mutants slac1 (originally rcd3), ost1, abi1-1 and abi2-1 lacked RTD completely. As the ozone sensitive mutant slac1 lacked RTD, the next aim of this study was to identify and characterize SLAC1. SLAC1 was shown to be a central regulator in response to all major factors regulating guard cell aperture: CO2, light/darkness transitions, ozone, relative air humidity, ABA, NO, H2O2, and extracellular Ca2+. It encodes the first guard cell plasma membrane slow type anion channel to be identified at the molecular level. Interestingly, the rapid type anion conductance was intact in slac1 mutant plants. For activation, SLAC1 needs to be phosphorylated. Protein kinase OST1 was shown to phosphorylate several amino acids in the N-terminal tail of SLAC1, Ser120 was one of its main targets, which led to SLAC1 activation. The lack of RTD in type 2C protein phosphatase mutants abi1-1 and abi2-1, suggests that these proteins have a regulatory role in ozoneinduced activation of the slow type anion channel.

Postmenopausal hot flushes, vascular health and hormone therapy

Vasomotor hot flushes are complained of by approximately 75% of postmenopausal women, but their frequency and severity show great individual variation. Hot flushes have been present in women attending observational studies showing cardiovascular benefit associated with hormone therapy use, whereas they have been absent or very mild in randomized hormone therapy trials showing cardiovascular harm. Therefore, if hot flushes are a factor connected with vascular health, they could perhaps be one explanation for the divergence of cardiovascular data in observational versus randomized studies. For the present study 150 healthy, recently postmenopausal women showing a large variation in hot flushes were studied in regard to cardiovascular health by way of pulse wave analysis, ambulatory blood pressure and several biochemical vascular markers. In addition, the possible impact of hot flushes on outcomes of hormone therapy was studied. This study shows that women with severe hot flushes exhibit a greater vasodilatory reactivity as assessed by pulse wave analysis than do women without vasomotor symptoms. This can be seen as a hot flush-related vascular benefit. Although severe night-time hot flushes seem to be accompanied by transient increases in blood pressure and heart rate, the diurnal blood pressure and heart rate profiles show no significant differences between women without and with mild, moderate or severe hot flushes. The levels of vascular markers, such as lipids, lipoproteins, C-reactive protein and sex hormone-binding globulin show no association with hot flush status. In the 6-month hormone therapy trial the women were classified as having either tolerable or intolerable hot flushes. These groups were treated in a randomized order with transdermal estradiol gel, oral estradiol alone or in combination with medroxyprogesterone acetate, or with placebo. In women with only tolerable hot flushes, oral estradiol leads to a reduced vasodilatory response and increases in 24-hour and daytime blood pressures as compared to women with intolerable hot flushes receiving the same therapy. No such effects were observed with the other treatment regimes or in women with intolerable hot flushes. The responses of vascular biomarkers to hormone therapy are unaffected by hot flush status. In conclusion, hot flush status contributes to cardiovascular health before and during hormone therapy. Severe hot flushes are associated with an increased vasodilatory, and thus, a beneficial vascular status. Oral estradiol leads to vasoconstrictive changes and increases in blood pressure, and thus to possible vascular harm, but only in women whose hot flushes are so mild that they would probably not lead to the initiation of hormone therapy in clinical practice. Healthy, recently postmenopausal women with moderate to severe hot flushes should be given the opportunity to use hormone therapy alleviate hot flushes, and if estrogen is prescribed for indications other than for the control of hot flushes, transdermal route of administration should be favored.

Juvenile neuronal ceroid lipofuscinosis; psychiatric symptoms, GAD-autoantibodies, and response to medication

Juvenile neuronal ceroid lipofuscinosis (JNCL) is one of the most common neurodegenerative diseases in childhood. Its clinical onset, with visual failure as the first sign, is between the ages of 4 to 8 years. During the disease progress, epilepsy, motor symptoms, cognitive decline, and psychiatric symptoms become apparent. It leads to premature death between ages 15 and 30. Treatment consists of symptomatic drug administration and various forms of rehabilitation, but to date, no curative treatment exists. To gain a more comprehensive picture of psychiatric problems, symptoms were evaluated by the Child Behavior Checklist, the Teacher Report Form, and the Children s Depression Inventory. The JNCL patients had a great number of severe psychiatric symptoms, with wide inter-individual variability. The most common symptoms were social, thought, attention, and sleep problems, somatic complaints, and aggressive behaviour. Patients with psychotropic treatment had more problems than did those without psychotropic treatment, and female patients had more problems than did males. Between 10 and 20% of the patients reported depressive symptoms. In a 5-year follow-up, [123I]β-CIT SPECT and MRI revealed a tendency of decreasing serotonin transporter (SERT) availability and progressive brain atrophy. The correlation between changes in midbrain SERT and total brain volume was positive; no correlation appeared between SERT or brain atrophy and depressive symptoms. Thus, it seems likely that the low SERT availability is associated with progressive brain atrophy; it may also predispose towards depression, however. An open survey of psychotropic drugs and their efficacy was performed on JNCL patients in Finland. The most commonly used psychotropic drugs were the antidepressant citalopram and the antipsychotic risperidone. Their efficacy was good or satisfactory in the majority of cases and they seemed well tolerated. Quetiapine had a marked effect on one patient with a history of severe psychotic symptoms. Glutamate decarboxylase 65 autoantibodies (GAD65ab), found in JNCL patients, indicate that an immunomediated reaction against GAD or GABAergic neurons may play a part in the underlying pathogenetic mechanism. GAD65ab s also appeared in the serum of all eight JNCL patients included and intermittent corticosteroid therapy was initiated in all cases. After one year, the GAD65ab s had disappeared in the two oldest patients, who experienced an improvement in motor symptoms and alertness associated with their prednisolone therapy. Two younger patients experienced a significant IQ increase, but no change in GADab s. A randomized study with longer follow-up time is needed, however, to clarify the effect of prednisolone on disease progression.

Studies on the assessment of the adequacy of anesthesia

Several hypnosis monitoring systems based on the processed electroencephalogram (EEG) have been developed for use during general anesthesia. The assessment of the analgesic component (antinociception) of general anesthesia is an emerging field of research. This study investigated the interaction of hypnosis and antinociception, the association of several physiological variables with the degree of intraoperative nociception, and aspects of EEG Bispectral Index Scale (BIS) monitoring during general anesthesia. In addition, EEG features and heart rate (HR) responses during desflurane and sevoflurane anesthesia were compared. A propofol bolus of 0.7 mg/kg was more effective than an alfentanil bolus of 0.5 mg in preventing the recurrence of movement responses during uterine dilatation and curettage (D C) after a propofol-alfentanil induction, combined with nitrous oxide (N2O). HR and several HR variability-, frontal electromyography (fEMG)-, pulse plethysmography (PPG)-, and EEG-derived variables were associated with surgery-induced movement responses. Movers were discriminated from non-movers mostly by the post-stimulus values per se or normalized with respect to the pre-stimulus values. In logistic regression analysis, the best classification performance was achieved with the combination of normalized fEMG power and HR during D C (overall accuracy 81%, sensitivity 53%, specificity 95%), and with the combination of normalized fEMG-related response entropy, electrocardiography (ECG) R-to-R interval (RRI), and PPG dicrotic notch amplitude during sevoflurane anesthesia (overall accuracy 96%, sensitivity 90%, specificity 100%). ECG electrode impedances after alcohol swab skin pretreatment alone were higher than impedances of designated EEG electrodes. The BIS values registered with ECG electrodes were higher than those registered simultaneously with EEG electrodes. No significant difference in the time to home-readiness after isoflurane-N2O or sevoflurane-N2O anesthesia was found, when the administration of the volatile agent was guided by BIS monitoring. All other early and intermediate recovery parameters were also similar. Transient epileptiform EEG activity was detected in eight of 15 sevoflurane patients during a rapid increase in the inspired volatile concentration, and in none of the 16 desflurane patients. The observed transient EEG changes did not adversely affect the recovery of the patients. Following the rapid increase in the inhaled desflurane concentration, HR increased transiently, reaching its maximum in two minutes. In the sevoflurane group, the increase was slower and more subtle. In conclusion, desflurane may be a safer volatile agent than sevoflurane in patients with a lowered seizure threshold. The tachycardia induced by a rapid increase in the inspired desflurane concentration may present a risk for patients with heart disease. Designated EEG electrodes may be superior to ECG electrodes in EEG BIS monitoring. When the administration of isoflurane or sevoflurane is adjusted to maintain BIS values at 50-60 in healthy ambulatory surgery patients, the speed and quality of recovery are similar after both isoflurane-N2O and sevoflurane-N2O anesthesia. When anesthesia is maintained by the inhalation of N2O and bolus doses of propofol and alfentanil in healthy unparalyzed patients, movement responses may be best avoided by ensuring a relatively deep hypnotic level with propofol. HR/RRI, fEMG, and PPG dicrotic notch amplitude are potential indicators of nociception during anesthesia, but their performance needs to be validated in future studies. Combining information from different sources may improve the discrimination of the level of nociception.

Carotid Stenosis, Endarterectomy, and the Brain : Brain microcirculation, diffusion, and cognitive function before and after carotid endarterectomy in patients with a high-grade carotid stenosis

Carotid atherosclerotic disease is a major cause of stroke, but it may remain clinically asymptomatic. The factors that turn the asymptomatic plaque into a symptomatic one are not fully understood, neither are the subtle effects that a high-grade carotid stenosis may have on the brain. The purpose of this study was to evaluate brain microcirculation, diffusion, and cognitive performance in patients with a high-grade stenosis in carotid artery, clinically either symptomatic or asymptomatic, undergoing carotid endarterectomy (CEA). We wanted to find out whether the stenoses are associated with diffusion or perfusion abnormalities of the brain or variation in the cognitive functioning of the patients, and to what extent the potential findings are affected by CEA, and compare the clinically symptomatic and asymptomatic subjects as well as strictly healthy controls. Coagulation and fibrinolytic parameters were compared with the rate microembolic signals (MES) in transcranial Doppler (TCD) and the macroscopic appearance of stenosing plaques in surgery. Patients (n=92) underwent CEA within the study. Blood samples pertaining to coagulation and fibrinolysis were collected before CEA, and the subjects underwent repeated TCD monitoring for MES. A subpopulation (n= 46) underwent MR imaging and repeated neuropsychological examination (preoperative, as well 4 and 100 days after CEA). In MRI, the average apparent diffusion coefficients were higher in the ipsilateral white matter (WM), and altough the interhemispheric difference was abolished by CEA, the levels remained higher than in controls. Symptomatic stenoses were associated with more sluggish perfusion especially in WM, and lower pulsatility of flow in TCD. All patients had poorer cognitive performance than healthy controls. Cognitive functions improved as expected by learning effect despite transient postoperative worsening in a few subjects. Improvement was greater in patients with deepest hypoperfusion, primarily in executive functions. Symptomatic stenoses were associated with higher hematocrit and tissue plasminogen activator antigen levels, as well as higher rate of MES and ulcerated plaques, and better postoperative improvement of vasoreactivity and pulsatility. In light of the findings, carotid stenosis is associated with differences in brain diffusion, perfusion, and cognition. The effect on diffusion in the ipsilateral WM, partially reversible by CEA, may be associated with WM degeneration. Asymptomatic and symptomatic subpopulations differ from each other in terms of hemodynamic adaptation and in their vascular physiological response to removal of stenosis. Although CEA may be associated with a transient cognitive decline, a true improvement of cognitive performance by CEA is possible in patients with the most pronounced perfusion deficits. Mediators of fibrinolysis and unfavourable hemorheology may contribute to the development of a symptomatic disease in patients with a high-grade stenosis.