The ability of an individual to withstand elevated head-to-toe gravitoinertial (+Gz) forces is determined by the capacity of their body to maintain sufficient head-level arterial pressure. Recent studies have shown a relationship between resting blood-vessel stiffness and an individual’s +Gz-tolerance, although the mechanisms behind this relationship are unclear. The aim of this project is to determine whether or not +Gz-tolerance is affected by a change inresting vasomotor tone. To evaluate this relationship, seven participants were asked to complete a +Gz-tolerance protocol using a human-use centrifugeon two different occasions. On both visits, gradual onset rate (0.1 G.s−1)and rapid onset rate (3.5 G.s−1) tests were done to evaluate the participants+Gz-tolerance. On one of the two visits, prior to the +Gz-tolerance testing,participants performed a 20-min cycle intervention to induce postexercisehypotension, with the aim of temporarily reducing participants’ resting bloodpressure and vasomotor tone. The cycling intervention was successful atinducing postexercise hypotension, as mean arterial pressure was significantlylower on the cycling visit (P<0.05). +Gz-tolerance was significantly lower(P<0.05) on the cycling visit compared with the non-cycling visit for both theGOR and ROR tests (absolute difference of 0.5 G and 0.25 G, respectively).The effect of the type of test on +Gz-tolerance was not influenced by the effectof the cycling intervention (P>0.05). Being the most documented mechanismlinked to postexercise hypotension, sustained vasodilation was assumed tohave occurred. This would have increased distensibility of the affected vessels,explaining the decrease in +Gz-tolerance. The decrease in +Gz-tolerance wassimilar for both tests, indicating that the baroreflex was not affected by thecycling intervention. Assuming that vasodilation occurred, this study showedthat a decrease in resting vasomotor tone decreased +Gz-tolerance, indicatingthe importance of this variable in the relationship between resting blood-vesselstiffness and an individual’s +Gz-tolerance.

Introduction: Changes in eating habits and incorporation of physical activities remain to be the main methods in treating obesity. To set an adequate calorie intake, which would lead to weight loss, it is necessary to determine energy needs of an individual. For that energy intake and energy expenditure need to be determinate. However, energy expenditure is difficult to determine since it is contributed of three components. Basal, respectively resting metabolic rate (RMR), which is affected by a body composition, has the greatest influence on a total energy expenditure. Indirect calorimetry (IC) is considered to be a gold standard to determine RMR. When RMR is calculated by prediction equations instead, such as Harris-Benedict (H-B) equation, energy needs are overestimate or underestimate for people with abnormal body composition. Objectives: The aim of this study is to analyse data of RMR obtained using IC in connection to body composition. The main aim is to determine how fat free mas (FFM) and fat mass (FM) are affecting RMR in obese patients. There is also a comparation of RMR measured by the IC and RMR calculated using H-B equation as a part of this study, while IC is considered to be a reference method. Methods: Patients new to ambulance of obesitology at General University Hospital in Prague...

The purpose of this study was to investigate the role exercise intensity plays in reducing body weight and percent body fat in overweight women. Subjects were randomized to either a high intensity interval training group (IT) or a lower intensity steady state training group (ST). Each group exercised 3 times per week for 8 weeks and expended 300 kcal per exercise session. VO2max, body composition, and resting metabolic rate (RMR) were measured pre and post training. RMR was measured after exercise at week 2 to see if intensity levels affected RMR. VO2max and body composition improved in IT but not in ST. Neither group showed a change in RMR from pretest to posttest; however, IT had an increase in RMR 24 hours post-exercise whereas ST did not. These findings show that high intensity interval exercise produces improvements in body composition, fitness, and acute RMR compared to low intensity steady state training.

Many events associated with Human Immunodeficiency Virus (HIV) infection/replication occur in and around the germinal centers (GCs) of secondary lymphoid tissues where follicular dendritic cells (FDCs) reside, suggesting that this microenvironment may contribute unique signaling that is important to viral progression. My research focused on characterizing signaling, both positive and negative, contributed by FDCs that affects HIV infection and replication. Specifically, I determined if FDC signals could induce the expression of latent HIV in T cells and if so, to characterize the signaling pathways involved. Moreover, I also examined the ability of FDCs to produce inhibitory signals that might block active virus expression. I approached these problems using FDCs from tonsils and coculturing these with primary CD4+ T cells or latently-infected Jurket cells with a GFP reporter. Results indicated that FDCs dramatically augmented HIV production of these cells. FDC signaling was costimulatory in nature and was mediated by soluble TNFα. However, when ex vivo latently infected T cells were treated with PMA/ionomycin or IL2/IL7, little virus expression was observed until FDCs were added, which greatly increased virus production. The transcription factor NFAT is important for the reactivation of latent HIV. Inhibition studies as well as ELISA suggested that JAK/STAT signaling pathway was involved in virus reactivation. Because FDCs produce prostaglandins (PGs) E2 and I2, I determined the effect of PGE2 and PGI2 analogs on HIV infected T cells. Results indicated that both the PGE2 and PGI2 analogs inhibited proliferation and activation-induced cell death of HIV infected T cells in a dose- and time-dependent manner. Additionally, it was shown that indomethacin and CAY10404, cyclooxygenase and cyclooxygenase-2 inhibitors, partially restored HIV production in the presence of FDCs, suggesting that FDC-produced PGE2 and PGI2 may inhibit virus replication. Thus, FDCs produce PGs that can block virus gene expression in T cells, which may be ideal for viral persistence. Therefore, FDC signaling appears to both promote and inhibit HIV production. A better understanding of FDC signaling and regulation in GCs may suggest new treatment strategies that would be beneficial to infected subjects.

The Academy of Nutrition and Dietetics has developed an evidence analysis library (EAL) for Nutrition and Dietetics professionals. The EAL is updated by members through workgroups consisting of experts in their fields, most often in response to unanswered questions. One such question is: what kinds of activities can be done during the rest period of an indirect calorimetry test in a healthy population? The objective of our study was to determine if listening to self-selected relaxing music or reading on an electronic device or a magazine effects resting energy expenditure (REE) as measured by an indirect calorimetry test in a healthy population. Answering this question would help indirect calorimetry test administrators know if these simple activities can be done during an indirect calorimetry test without significantly affecting REE but helping subjects remain awake. It would also help standardize the current protocol for indirect calorimetry administration. A randomized trial was conducted during an indirect calorimetry test, under three different conditions (resting, reading, listening to music). Six-five subjects (36 females and 29 males) were used in final data analysis. Inclusion criteria included healthy subjects between the ages of 18-50 years with a stable weight. Exclusion criteria included pregnant or lactating women or individuals who were taking medications known to affect metabolism. Reading, either a magazine or electronic device, resulted in a significant increase of 102.7 kcal/day when compared to resting (p<0.0001). There was no difference in REE when subjects read a magazine or on an electronic device. Listening to self-selected relaxing music increased REE by 27.6 kcal/day compared to rest (p=0.0072). Based on our results, we recommend subjects refrain from reading a magazine or electronic device during a test. Whether or not the smaller difference found while listening to music is practically significant would be a decision for the indirect calorimetry test administrators. Further research could be done to determine the effects other activities have on REE during an indirect calorimetry test. Such activities could include; watching television, texting, or playing passive game.

The brain connectivity of resting-state fMRI (rs-fMRI) represents an intrinsic state of brain architecture, and it has been used as a useful neural marker for detecting psychiatric conditions such as autism spectrum disorder, as well as for predicting psychosocial characteristics such as age. However, most studies using brain connectivity have focused more on the strength of functional connectivity over time (static-FC) than temporal features of connectivity changes (connectome variability). The primary goal of the current study was to investigate the effectiveness of using the connectome variability in classifying an individual’s pathological characteristics from others and predicting psychosocial characteristics. In addition, the current study aimed to prove that benefits of the connectome variability are reliable across various analysis procedures. To this end, three open public large rs-fMRI datasets including ABIDE, COBRE, and NKI were used. The static-FC and the connectome variability metrics were calculated with various brain parcellations and parameters and then utilized for subsequent machine learning (ML) classification and prediction. The results demonstrated that including the connectome variability increased the ML performances significantly in most cases of analytical variations. In addition, including the connectome variability prevented ML performance deterioration when excessive components were used. In conclusion, the current finding proved the usefulness of the connectome variability and its reliability. / M.S. / Functional magnetic resonance imaging (fMRI) with functional connectivity (FC) analysis has been widely used to understand the human brain’s system and cognitive processes. Especially, the resting-state fMRI (rs-fMRI) has been regarded as a comprehensive map of the brain’s large-scale functional architecture. Previous seminal findings demonstrated that brain regions show synchronized patterns even without any external stimulus or task (Biswal et al., 1995; Power et al., 2011), and recent studies also demonstrated that functional network architecture during tasks can be formed based on resting-state network architecture primarily suggesting that the resting-state is an intrinsic and fundamental of brain organization functionally. At the early stage of fMRI FC studies, researchers commonly adopted static measure of connectivity (static-FC) such as Pearson correlation. However, the brain has a dynamic nature, thus the static approach does not capture temporal information of the brain. In this context, time-varying or dynamic-FC has been suggested as a promising substitute. The derived dynamic-FC usually has been used to distinguish several dynamic states by identifying repeated spatial dynamic-FC profiles. Another utilization is quantifying moment-to-moment changes of dynamic-FC (connectome variability) which can represent how much dynamic-FC is stable. Interestingly, although its importance of dynamic-FC temporal features, few studies have utilized connectome variability. In addition, only a few studies compared static-FC and connectome variability (Fong et al., 2019; Wang et al., 2018). Therefore, it is necessary to demonstrate the benefits of connectome variability and its reliability across various cognitive domains and analytic procedures. To this aim, this study used three large open fMRI datasets: ABIDE comprised of autism spectrum disorder and typical development, COBRE comprised of schizophrenia and control group, and NKI which is a developmental dataset across the lifespan. In individuals’ resting-state fMRI, brain signal time series was extracted using various parcellation methods including AAL2 atlas (Rolls et al., 2015), bilateralized AAL2 atlas, and LAIRD network atlas (Laird et al., 2011). To calculate static-FC, pairwise Pearson correlation was used. For the dynamic-FC, sliding-window correlation was used with 60 second window size. Additional 90 second and 120 second sliding window sizes were also used to test the reliability of the current study. The additional sliding window sizes showed almost identical results to that of the main sliding window size (60s). The derived dynamic-FC was used to calculate ‘connectome variability’ using mean square successive difference (MSSD). The calculated static-FC and the connectome variability were inputted to support vector machine (SVM) for group classifications or support vector regression (SVR) for predicting individuals’ characteristics. Before machine learning analysis (SVM, SVR), lasso regression was adopted as a feature selection method. The SVM results showed that including connectome variability increased group classification performances in ABIDE and COBRE datasets. Interestingly, including connectome variability improved the robustness of SVM classification when the number of components was controlled. Similarly, the SVR results also demonstrated that including connectome variability increased prediction performances for autism symptom severity score (ADOS), social responsiveness score (SRS), and individuals’ age. These benefits were consistent across three parcellation schemes. In conclusion, the current study demonstrated that the connectome variability is useful to classify different groups and to predict individuals’ characteristics. Such benefits were reliable across multiple cognitive domains and robust to several analytic procedures. These results emphasized that the connectome variability which has been usually overlooked reflects some aspects of functional brain architecture, and future fMRI studies should more attend connectome variability between brain regions.

Extensive research has been conducted on the relationship between brain activity and personality traits, and several theories propose a lateralization of specific personality qualities. A prominent model suggests frontal lateralization of motivational direction, specifically, the behavioral inhibition and activation systems (BIS/BAS), with greater right frontal activity linked to behavioral inhibition and greater left frontal activity linked to behavioral activation. Recent studies have presented contrasting findings in the absence of this correlation. With the present study I aimed to investigate the link between frontal lateralization and the BIS/BAS. I further examined the test-retest reliability of resting-state frontal alpha asymmetry (FAA), and of the BIS/BAS scale. Resting-state frontal EEG asymmetry and participants’ responses to the BIS/BAS scale were collected from University of Skövde students on multiple occasions. FAA were obtained from electrode sites F4-F3, F6-F5, and F8-F7 over three sessions, two weeks apart, along with BIS/BAS scores from the first and third sessions. Within-subject FAA showed variability over time, suggesting FAA to be a less reliable measure of personality traits. Only two out of the four BIS/BAS subscales demonstrated consistent scores, raising doubts about the reliability of using it to assess personality traits. BAS Drive correlated negatively with FAA, contrary to the expected direction, but no other significant correlation was observed between resting-state FAA and BIS/BAS. Verifying FAA as an indicator of BIS and BAS is important for drawing meaningful associations between them. Future research should consider employing a repeated measures design and a larger sample size to enhance the understanding of this relationship.

Children and adolescents with concussion display aberrant functional connectivity in some of the major neurocognitive networks. This includes the Default Mode Network, Central Executive Network and Salience Network. Using resting state fMRI, the purpose of this thesis was to explore the functional connectivity of cognition-related networks in youth experiencing concussion. With a prospective cohort study, the functional connectivity (defined as the temporal coherence between spatially separated brain regions) of children and adolescents ages 10-18 years old was evaluated in relation to a number of demographic and injury-specific factors including recovery length, age at the time of injury, symptom severity, and neurocognitive performance. The results showed two general trends: (1) a reduction in connectivity (i.e., hypoconnectivity) between the regions of the Default Mode Network, and (2) an increase in connectivity (i.e., hyperconnectivity) between additional sensory-related regions like the cerebellum and hippocampus. The Default Mode Network, which processes self-referential information, has a long-protracted development across childhood through adulthood. Given that the participants in this cohort exhibited reduced functional connectivity within the Default Mode Network and between the Default Mode Network and other neurocognitive networks suggests that this is an area of vulnerability in youth in the event of concussion. Increased connectivity between the Central Executive Network and Salience Network, and between cognitive- and sensory-related regions such as the hippocampus and cerebellum might be interpreted as a compensatory mechanism to supplement deficits of the Default Mode Network. This thesis sheds light on important concussion-related regions for future research to investigate further and delves into the possible neural mechanisms contributing to the cognitive, sensory, mood, and sleep disturbances in children and adolescents with concussion. / Dissertation / Doctor of Philosophy (PhD) / Your brain at rest is not resting. In fact, your many brain regions are continuously communicating even during rest to maintain important communication between them. This communication between brain regions is termed functional connectivity. When you receive a blow to the head, face, neck, or another part of your body that senses a biomechanical force to your brain, the functional connectivity (i.e., communication lines) between your brain regions may be altered. A blow of this nature is considered a concussion, also known as a mild traumatic brain injury. With disruptions to the typical functional connectivity between your brain regions following a concussion, you may experience difficulty in managing cognitive tasks, emotions, and body coordination. Among those most vulnerable to the effects of concussion are children and adolescents whose brains have yet to develop fully. The goal of this thesis was to evaluate the functional connectivity between brain regions of children and adolescents to determine how brain communication might be disrupted following concussion. These evaluations were done using functional magnetic resonance imaging (fMRI) of the brains of children and adolescents ages 10-18 years old. It was discovered that the functional connectivity of the frontal lobe is related severity of post-concussion symptoms such that individuals with worse symptoms had reduced functional connectivity in the frontal lobe compared to individuals who reported less severe symptoms. Further, children and adolescents with longer recovery periods have a different level of functional connectivity in the temporal lobe compared to youth with relatively shorter recovery periods. This might suggest that both of these regions could provide prognostic value in determining who might have worse symptoms or a longer recovery time following injury. In comparison to children and adolescents who have not had a concussion, children and adolescents experiencing a concussion are more likely to have abnormal functional connectivity between the hippocampus and cerebellum, which are particularly involved in processing sensory information and navigation. This was interpreted to mean that the brain responded to the concussion by increasing the communication between regions that might help a child with a concussion coordinate their bodies so that they can move from place to place. This was additionally supported by a further investigation which showed that children and adolescents have reduced communication between areas of the brain that might allow them to process information about the self (e.g., memories, sensations, relationships with others, etc.). Overall, the results demonstrated that following a concussion, children and adolescents may have a deficit in the functioning of the frontal lobe in a specific region that allows them to process cognitive and sensory information. This might explain why concussion leads to poor memory, body coordination, sensitivity to light and sounds, and even difficulty sleeping. Their brains might then compensate for the disruption by increasing alternate pathways of communication. Together these findings open gateways for future researchers to look more deeply at the specific regions affected by concussion in youth. It draws attention to the many neurocognitive, emotional, and somatic symptoms a child with a concussion exhibits and their symptoms’ underlying neurological processes.

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