We conducted a systematic review of the neuroimaging literature examining cognition in old and young adults and quantified these findings in a series of meta-analyses using the activation likelihood ...estimation technique. In 80 independent samples, we assessed significant convergent and divergent patterns of brain activity across all studies; where task performance was equated or different between age groups; and in four specific cognitive domains (perception, memory encoding, memory retrieval and executive function). Age differences across studies predominantly involved regions within the ‘task-positive network’ of the brain, a set of interconnected regions engaged during a variety of externally driven cognitive tasks. Old adults engaged prefrontal regions more than young adults. When performance was equivalent, old adults engaged left prefrontal cortex; poorly performing old adults engaged right prefrontal cortex. Young adults engaged occipital regions more than old adults, particularly when performance was unequal and during perceptual tasks. No age-related differences were found in the parietal lobes. We discuss the reliable differences in brain activation with regards to current theories of neurocognitive aging.
University athletes are at high risk for both substance use and mental health problems. This study examined associations between substance use, mental health symptoms, and the resting state ...functional connectivity (rsFC) of key neural regions involved in self-monitoring and emotional regulation in a sample of female varsity athletes. 31 female university athletes completed measures of substance use, mental health symptoms, and underwent functional MRI scans during the pre-season. Athletes who were substance users had higher symptoms of depression than non-users (p = 0.04; Hedge's g = 0.81). RsFC differences were observed between users and non-users in orbital frontal cortex (OFC) and bilateral hippocampal seeds, and negative associations between depression symptoms and rsFC in the left hippocampus and posterior cingulate cortex were observed in cannabis users. In female athletes, substance use is associated with greater self-reported depression symptoms and altered rsFC in self-monitoring and emotional regulation regions of the brain.
Examining non-sport-related cognitive tasks of attention and executive control in skilled athletes may provide insight into the acquisition of highly specific skills developed in experts as well as ...help identify successful performance in sport. Through a cross-sectional design, this study examined performance on aspects of attention and executive control among varsity athletes playing soccer (strategic sport) or track & field (static sport) using a computerized test of attention and executive control. Ninety-seven university athletes participating in soccer (n = 50) or track and field (n = 47) were included in the study. Domains of attention and executive control were examined using the Attention Network Test-Interactions (ANT-I). Mean reaction time (RT) and intra-individual variability (IIV) were compared between groups as measures of performance speed and performance stability respectively. Soccer players demonstrated overall faster RTs (p = 0.0499; ηp2 = .04) and higher response accuracy (p = .021, d = .48) on the ANT-I compared to track and field athletes. Faster RTs were observed for soccer players when presented with an alerting tone (p = .029, d = .45), valid orienting cue (p = .019, d = .49) and incongruent flanker (p = .031, d = .45). No significant group differences were observed in IIV (p = .083, d = .36). Athletes engaging in strategic sports (i.e., soccer) demonstrated faster performance under test conditions that required higher vigilance and conflict resolution. These findings suggest that engagement in strategic sports is associated with enhanced performance on non-sport-related cognitive tasks of attention and executive control.
To systematically review the literature on the long-term neuroimaging findings (≥10 years from exposure) for exposure in adulthood to mild traumatic brain injury (mTBI) and repetitive head impacts ...(RHIs) using neuroimaging across all available populations.
Four electronic databases: MEDLINE, SPORTDiscus, PsycINFO, and EMBASE.
All articles were original research and published in English. Studies examined adults with remote exposure to mTBI and/or RHIs from ten or more years ago in addition to any associated neuroimaging findings.
Parameters mainly included participants' population, age, years since head injury, race, sex, education level, and any neuroimaging findings. Scores for the level of evidence and risk of bias were calculated independently by two authors.
5,521 studies were reviewed, of which 34 met inclusion criteria and were included in this study. The majority of adults in these studies showed positive neuroimaging findings one or more decades following mTBI/RHI exposure. This was consistent across study populations (i.e., veterans, athletes, and the general population). There was evidence for altered protein deposition patterns, micro- and macro-structural, functional, neurochemical, and blood flow-related differences in the brain for those with remote mTBI/RHI exposure.
Findings from these studies suggest that past mTBI/RHI exposure may be associated with neuroimaging findings. However, given the methodological constraints related to relatively small sample sizes and the heterogeneity in injury types/exposure and imaging techniques used, conclusions drawn from this review are limited. Well-designed longitudinal studies with multimodal imaging and in-depth health and demographic information will be required to better understand the potential for having positive neuroimaging findings following remote mTBI/RHI.
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•TR-MMMs were fabricated from MFI and MCM-41 filled poly(hydroxyimide)s.•The prepared TR-MMMs showed improved gas permeability and maintained selectivity.•The positive contribution of ...filler depended strongly on the kind of matrix.•The MFI filled 6FDA based polyimide and its TR analogue surpassed other systems.
In this study, we explore the use of two kinds of inorganic sieves, microporous MFI zeolite and mesoporous MCM-41 silica, as fillers to enhance the gas transport characteristics of thermally rearranged (TR) poly(hydroxyimides) (HPI). To the best of our knowledge, this is the first report on the use of these fillers to modify properties of TR HPIs, except for our previous research on MCM-41 filled HPIs based on BPADA dianhydride. In this work, 6FDA-HAB and BPADA-HAB varying in gas permeability and properties were selected as matrices for preparation of mixed matrix membranes (MMM) with the aim of studying the effect of both the kind of filler and a matrix on thermal rearrangement and properties of the resultant TR-MMMs. In addition to pure gas permeability measurements, HPIs and MMMs were examined by WAXD, SEM, TGA, DMA, and tensile tests before and after thermal rearrangement. For all MMM precursors, the permeability increased in proportion to the filler loading (e.g. by 1.2–4.4 times for O2) while selectivity remained virtually the same. The same effect of improved permeability and maintained selectivity was observed for the series of TR-MMMs; for example, TR-MMM based on 6FDA and filled with 7 wt% of MCM-41 exhibited 6.7 fold higher O2 permeability over its filled precursor. The permeation properties of the filled membranes showed a strong dependence on both the kind of matrix and filler. The addition of MCM-41 particles to BPADA-HAB increased permeability more than the incorporation of the similar amount of MFI ones, while the contrary was true for 6FDA-HAB. The best result, comprising the position on the upper bound for He/N2, has been achieved for 6FDA-HAB filled with 25 wt% of MFI, whereas its TR analogue showed the highest 20.4 fold permeability improvement.
The gas transport properties of the mixed matrix membranes (MMM) prepared from the synthesized, structurally different poly(hydroxyimide)s (HPI) and mesoporous MCM-41 silica particles were ...investigated. The both series of filled and unfilled precursors were used to obtain and examine thermally rearranged (TR) polybenzoxazoles (PBO). The effect of a number and position of hydroxyl groups in HPI chains as well as that of filler presence on TR conversion was studied using FTIR, DSC, TGA, WAXD, SEM, mechanical testing, and density measurements. With 7 wt% of MCM-41 silica, gas permeability of the filled HPI precursors and that of the respective filled PBOs increased 1.5–2.2 and 4.4–15.1 times, respectively, comparing to the neat HPIs. The permeability increase along with relatively low loss of gas selectivity for filled membranes shift them towards the upper bound demonstrating that incorporation of porous fillers into polybenzoxazoles precursors can be a new approach to improve membrane performance.
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•Mesoporous MCM-41 and structurally diverse poly(hydroxyimide)s were synthesized.•Mixed matrix membranes containing 7 wt% of MCM-41 were successfully fabricated.•Pure and filled poly(hydroxyimide)s were efficiently converted in polybenzoxazoles.•Filling combined with thermal rearrangement increased gas permeability 4.4–15 times.•Relatively low loss of selectivity resulting from filler incorporation was noticed.
BACKGROUND In patients with chronic kidney disease (CKD), secondary hyperparathyroidism is assessed by measuring serum parathyroid hormone (PTH) levels. Well-established, recommended, ...second-generation intact parathyroid hormone (iPTH) tests are typical; rarely are more recent third-generation PTH 1-84 assays used. The agreement between results of the 2 tests in patients with CKD has not been sufficiently defined. MATERIAL AND METHODS This study aimed to compare Roche second- and third-generation PTH assays by establishing a quantitative relationship between the results of assays in patients with CKD and assessing degree of their correlation with kidney function and calcium-phosphate and bone metabolism parameters. In 205 patients with stages 3 to 5D CKD and 30 healthy controls, we measured levels of iPTH and PTH (1-84), creatinine, urea, cystatin C, calcium, inorganic phosphate, magnesium, alkaline phosphatase, bone alkaline phosphatase, osteocalcin, and ß-CrossLaps. RESULTS The third-generation PTH assay results were more than 40% lower than those obtained with the second-generation test in patients undergoing dialysis and approximately 30% lower in patients in the pre-dialysis period. PTH concentrations determined with both assays were almost to the same extent correlated with calcium-phosphate and bone metabolism parameters, and renal function indices. Formulas have been developed enabling 2-way conversion of PTH results determined with both the second- and third-generation PTH assays: For dialyzed patients, PTH (1-84)=0.5181iPTH+18.0595. Serum osteocalcin, ß-CrossLaps, and total calcium were independent predictors of PTH levels. CONCLUSIONS Correcting for the established quantitative differences, the second-and third-generation PTH tests can be used interchangeably, given the almost identical pathophysiological correlations of their results with calcium-phosphate and bone metabolism parameters.
In this paper, we show a series of the new noncovalent azosystems based on poly(amide imide) matrices. Azobenzene derivatives were attached to the polymer matrix via hydrogen bonds or formed doped ...systems. Additionally, glass transition temperatures of azosystems were established by the calculation procedure based on Fox equation. We proved that presence H-bonds between polymer matrix and chromophore does not effect on increase Tg and T5, in comparison to the doped polymers. It was observed that poly(amide imide) matrices are able to the thermally induced intermolecular cross-linking via hydrogen bonds. Functional density theory (DFT) was used to observed both changes in geometry the polymer matrix before and after incorporation of the azo-dyes and H-bonds formation possibility. The presence of H-bonds both intermolecular and between polymer and chromophore was confirmed experimentally by FTIR and 1H NMR spectroscopy. The supramolecular system based on the matrix with pyridine rings in the side chains and 4-(4-methyl phenyl)diazenylphenol was found to show a relatively efficient photo-orientation process. We showed the hydrogen bonds between chromophore and polymer matrix did not provide higher and more stable the photoinduced birefringence in comparison with doped one. It seems that the critical parameter which impacts on values and stability of Δn is azo-dye content.
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•Guest-host azopoly(amide imide) systems were prepared.•Chosen physicochemical properties and photochromic responses were measured.•Changes in geometry the polymer matrix before and after addition of the azo-dyes.•Structure-property relations were shown.
University athletes are exposed to numerous impacts to the body and head, though the potential cumulative effects of such hits remain elusive. This study examined resting-state functional ...connectivity (rsFC) of brain networks in female varsity athletes over the course of a season. Nineteen female university athletes involved in collision (
N
= 12) and contact (
N
= 7) sports underwent functional magnetic resonance imaging scans at both pre- and post-season. A group-level independent component analysis (ICA) was used to investigate differences in rsFC over the course of a season and differences between contact and collision sport athletes. Decreased rsFC was observed over the course of the season between the default mode network (DMN) and regions in the frontal, parietal, and occipital lobe (
p
false discovery rate, ≤0.05) driven by differences in the contact group. There was also a main effect of group in the dorsal attention network (DAN) driven by differences between contact and collision groups at pre-season. Differences identified over the course of a season of play indicate largely decreased rsFC within the DMN, and level of contact was associated with differences in rsFC of the DAN. The association between exposure to repetitive head impacts (RHIs) and observed changes in network rsFC supplements the growing literature suggesting that even non-concussed athletes may be at risk for changes in brain functioning. However, the complexity of examining the direct effects of RHIs highlights the need to consider multiple factors, including mental health and sport-specific training and expertise, that may potentially be associated with neural changes.
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