High Blood Pressure Is Associated with Lower Brain Volume and Cortical Thickness in Healthy Young Adults.

BACKGROUND: High blood pressure (BP) in middle-aged and older adults is associated with lower brain volume and cortical thickness assessed with structural MRI. However, little evidence is available in young adults. We investigated the associations of high BP with brain volumes and cortical thickness in healthy young adults. METHODS: This cross-sectional study included 1095 young adults (54% women, 22-37 years) from the Human Connectome Project (HCP) who self-reported not having a history of hypertension or taking antihypertensive medications. Brachial systolic (SBP) and diastolic BP (DBP) were measured with semi-automatic or manual sphygmomanometer during study visits. Structural MRI was used to measure gray matter (GM) and white matter (WM) volume and mean cortical thickness. Associations of BP and hypertension stage with total and regional brain volumes and cortical thickness were analyzed using linear regression and analysis of covariance (ANCOVA) after adjusting for age, sex, education years, body mass index (BMI), smoking, alcohol consumption history, zygosity, and total intracranial volume. RESULTS: SBP and DBP were (mean ± SD) 123.6 ± 14.2 and 76.5 ± 10.6 mmHg, respectively (n = 1095). High DBP was associated with lower total GM (p = 0.012), cortical GM (p = 0.004), subcortical GM (p = 0.012), and total WM volumes (p = 0.031). High SBP and DBP were associated with lower regional cortical volume and cortical thickness. CONCLUSION: These findings suggest that high BP may have deleterious effects on brain health at the early stage of adulthood.

Association of Blood Pressure With Brain White Matter Microstructural Integrity Assessed With MRI Diffusion Tensor Imaging in Healthy Young Adults.

BACKGROUND: High blood pressure (BP) in middle-aged and older adults is associated with a brain white matter (WM) microstructural abnormality. However, little evidence is available in healthy young adults. We investigated the associations between high BP and WM microstructural integrity in young adults. METHODS: This study included 1015 healthy young adults (542 women, 22-37 years) from the Human Connectome Project. Brachial systolic and diastolic BP were measured using a semiautomatic or manual sphygmomanometer. Diffusion-weighted magnetic resonance imaging was acquired to obtain diffusion tensor imaging metrics of free water (FW) content, FW-corrected WM fractional anisotropy, axial diffusivity, radial diffusivity, and mean diffusivity. Using whole-brain voxel-wise linear regression models and ANCOVA, we examined associations of BP and hypertension stage with diffusion tensor imaging metrics after adjusting for age, sex, education, body mass index, smoking status, alcohol consumption history, and differences in the b value used for diffusion magnetic resonance imaging. RESULTS: Systolic and diastolic BP of the sample (mean±SD) were 122.8±13.0 and 76.0±9.9 mm Hg, respectively. Associations of BP with diffusion tensor imaging metrics revealed regional heterogeneity for FW-corrected fractional anisotropy. High BP and high hypertension stage were associated with higher FW and lower FW-corrected axial diffusivity, FW-corrected radial diffusivity, and FW-corrected mean diffusivity. Moreover, associations of high diastolic BP and hypertension stage with high FW were found only in men not in women. CONCLUSIONS: High BP in young adults is associated with altered brain WM microstructural integrity, suggesting that high BP may have damaging effects on brain WM microstructural integrity in early adulthood, particularly in men.

Cerebral blood flow dynamics: Is there more to the story at exercise onset?

A monoexponential model characterizing cerebral blood velocity dynamics at the onset of exercise may mask dynamic responses by the cerebrovasculature countering large fluctuations of middle cerebral artery blood velocity (MCAv) and cerebral perfusion pressure (CPP) oscillations. Therefore, the purpose of this study was to determine whether the use of a monoexponential model attributes initial fluctuations of MCAv at the start of exercise as a time delay (TD). Twenty-three adults (10 women, 23.9 ± 3.3 yrs; 23.7 ± 2.4 kg/m2 ) completed 2 min of rest followed by 3 mins of recumbent cycling at 50 W. MCAv, CPP, and Cerebrovascular Conductance index (CVCi), calculated as CVCi = MCAv/MAP × 100 mmHg, were collected, a lowpass filter (0.2 Hz) was applied, and averaged into 3-second bins. MCAv data were then fit to a monoexponential model [ΔMCAv(t) = Amp(1 - e-(t-TD)/τ )]. TD, tau (τ), and mean response time (MRT = TD + τ) were obtained from the model. Subjects exhibited a TD of 20.2 ± 18.1 s. TD was directly correlated with MCAv nadir (MCAvN ), r = -0.560, p = 0.007, which occurred at similar times (16.5 ± 15.3 vs. 20.2 ± 18.1 s, p = 0.967). Regressions indicated CPP as the strongest predictor of MCAvN ( R a 2 $$ {R}_a^2 $$ = 0.36). Fluctuations in MCAv were masked using a monoexponential model. To adequately understand cerebrovascular mechanisms during the transition from rest to exercise, CPP and CVCi must also be analyzed. A concurrent drop in cerebral perfusion pressure and middle cerebral artery blood velocity at the start of exercise forces the cerebrovasculature to respond to maintain cerebral blood flow. The use of a monoexponential model characterizes this initial phase as a time delay and masks this large important response.

Effects of a Short-Term Heat Acclimation Protocol in Elite Amateur Boxers.

ABSTRACT: Stone, BL, Ashley, JD, Skinner, RM, Polanco, JP, Walters, MT, Schilling, BK, and Kellawan, JM. Effects of a short-term heat acclimation protocol in elite amateur boxers. J Strength Cond Res 36(7): 1966-1971, 2022-Boxing requires proficient technical and tactical skills coupled with high levels of physiological capacity. Although heat and humidity negatively affect acute exercise performance, short-term exercise training in hot and humid environments can lead to physiological adaptations that enhance exercise performance in both hot and thermoneutral conditions. In highly trained endurance athletes, exercise-induced acclimation can occur in as little as 5 days (known as short-term heat acclimation [STHA]). However, the impact of a 5-day heat acclimation (5-DayHA) in combat athletes, such as elite amateur boxers, is unknown. The aim of the present investigation was to determine whether a 5-DayHA improves aerobic performance in a thermoneutral environment and causes positive physiological adaptations in elite boxers. Seven elite amateur boxers underwent a 5-DayHA protocol, consisting of 60-minute exercise sessions in an environmental chamber at 32 °C and 70% relative humidity. Repeat sprint test (RST) evaluated aerobic performance in a thermoneutral environment 24 hours before and after the 5-DayHA. Presession and postsession hydration status (urine specific gravity) and body mass were assessed. After a 5-DayHA period, boxers significantly improved RST performance (13 ± 7 to 19 ± 7 sprints, d = 0.92, p = 0.03) but not pre-exercise hydration status (1.02 ± 0.01 to 1.01 ± 0.01, d = 0.82, p = 0.07). Therefore, these findings suggest 5-DayHA enhances aerobic performance in elite-level amateur boxers and may provide a viable training option for elite combat athletes.

High-resolution otolith elemental signatures in eteline snappers from valuable deepwater tropical fisheries.

Marine resources are often shared among countries, with some fish stocks straddling multiple Exclusive Economic Zones, therefore understanding the structure of populations is important for the effective management of fish stocks. Otolith chemical analyses could discriminate among populations based on differences in the chemical composition of otoliths. We used otoliths from two deepwater snappers (flame snapper Etelis coruscans and ruby snapper Etelis boweni) to examine the evidence for population structure across six Pacific Island countries using solution-based inductively coupled plasma mass spectrometry (ICP-MS) for otolith core and whole otolith samples and laser ablation ICP-MS (LA-ICP-MS) for core and edge areas of a cross-sectioned otolith. The inter-species comparison of these methods is important as the two species are often managed under the same regulations. For both species, the two methods demonstrated separation among the locations sampled with high classification accuracy. Smaller laser ablation spot size gave greater temporal resolution over the life-history transect. Comparing the early life-history section of the otoliths (i.e., the core), one interpretation is that young fish experienced more uniform environments in the open ocean as larvae than adults, as the elemental fingerprints had greater overlap among multiple locations. LA-ICP-MS methods had some advantages over solution-based ICP-MS and generally better discrimination for the trace elements investigated. There were substantial differences between species, but both methods suggested nonmixing populations at the regional scale. Otolith chemistry can be an effective tool in discriminating variation for deepwater marine species in multispecies fisheries, and edge measurements from LA-ICP-MS provided the greatest resolution. Although caution should be taken in interpreting the results from relatively small samples sizes, otolith chemical analyses could be useful at these spatial scales to investigate population structure. This information on separate or overlapping populations could be used in future regional fishery management plans.

Antisocial cognition as a mediator of the peer influence effect and peer selection effect in antisocial adolescents.

The peer influence and peer selection effects are two widely replicated findings in the criminological literature that refer to the predictive relationship between antisocial behaviour and delinquent peer association as well as between delinquent peer association and antisocial behaviour, respectively. Research suggests that antisocial cognition might constitute a causal mechanism underlying part of these effects. This study investigated the extent that the peer influence and peer selection effects are mediated by one key aspect of antisocial cognition-beliefs and attitudes supporting peer conflict. This study examined whether beliefs and attitudes supporting peer conflict mediated the relationship between delinquent peer association and volume of self-reported antisocial behaviour and vice-versa, across a 1-year follow-up period, in 683 (433 male, 250 female) British adolescents (mean age: 13.8 years) with a history of serious antisocial behaviour. Participants completed measures at baseline and 6, 12 and 18 months thereafter. Findings indicated that beliefs and attitudes supporting peer conflict partially mediated the peer influence and peer selection effects, explaining a substantial proportion of the total effect in the peer influence (i.e., 26%) and peer selection (i.e., 17%) models. These results suggest that beliefs and attitudes supporting peer conflict could explain part of the mechanism underlying the peer influence and peer selection effects in adolescents with a history of serious antisocial behaviour.

Cerebrovascular responses to graded exercise in young healthy males and females.

Although systemic sex-specific differences in cardiovascular responses to exercise are well established, the comparison of sex-specific cerebrovascular responses to exercise has gone under-investigated especially, during high intensity exercise. Therefore, our purpose was to compare cerebrovascular responses in males and females throughout a graded exercise test (GXT). Twenty-six participants (13 Females and 13 Males, 24 ± 4 yrs.) completed a GXT on a recumbent cycle ergometer consisting of 3-min stages. Each sex completed 50W, 75W, 100W stages. Thereafter, power output increased 30W/stage for females and 40W/stage for males until participants were unable to maintain 60-80 RPM. The final stage completed by the participant was considered maximum workload(Wmax ). Respiratory gases (End-tidal CO2 , EtCO2 ), middle cerebral artery blood velocity (MCAv), heart rate (HR), non-invasive mean arterial pressure (MAP), cardiac output (CO), and stroke volume (SV) were continuously recorded on a breath-by-breath or beat-by-beat basis. Cerebral perfusion pressure, CPP = MAP (0. 7,355 distance from heart-level to doppler probe) and cerebral vascular conductance index, CVCi = MCAv/CPP 100mmHg were calculated. The change from baseline (Δ) in MCAv was similar between the sexes during the GXT (p = .091, ωp2  = 0.05). However, ΔCPP (p < .001, ωp2  = 0.25) was greater in males at intensities ≥ 80% Wmax and ΔCVCi (p = .005, ωp2  = 0.15) was greater in females at 100% Wmax . Δ End-tidal CO2 (ΔEtCO2 ) was not different between the sexes during exercise (p = .606, ωp2  = -0.03). These data suggest there are sex-specific differences in cerebrovascular control, and these differences may only be identifiable at high and severe intensity exercise.

Understanding cognitive performance during exercise in Reserve Officers' Training Corps: establishing the executive function-exercise intensity relationship.

Military performance depends on high-level cognition, specifically executive function (EF), while simultaneously performing strenuous exercise. However, most studies examine cognitive performance following, not during, exercise. Therefore, our aim was to examine the relationship between EF and exercise intensity. Following familiarization, 13 Reserve Officers' Training Corp cadets (age = 19.6 ± 2 yr, five women) completed a graded exercise test (GxT) and two executive function exercise tests (EFETs) separated by a duration of ≥24 h. The EFET was a combined iPad-based EF test (Cedar Operator Workload Assessment Tool) and GxT. Heart rate (HR) and prefrontal cortex (PFC) oxygenation [near-infrared spectroscopy (NIRS)] were continuously recorded. The EF score was analyzed for accuracy of responses (%hit rate). Heart rate reserve was calculated to normalize exercise intensity (%HRR). For PFC oxygenation recordings, NIRS variables were used to calculate the tissue saturation index (%TSI). Data from EFET trials were averaged into a singular response. The %hit rate declined at heart rate reserves (HRRs) of ≥80%, reaching nadir at 100% HRR (74.09 ± 10.63%, P < 0.01). The tissue saturation index (TSI) followed a similar pattern, declining at ≥70% of HRR and at a greater rate during EFET compared with during GxT (P < 0.01), reaching a nadir in both conditions at 100% HRR (60.39 ± 2.94 vs. 63.13 ± 3.16%, P < 0.01). Therefore, EF decline is dependent on exercise intensity, as is %TSI. These data suggest that reductions in EF during high-intensity exercise are at least in part related to attenuated PFC oxygenation. Thus, interventions that improve PFC oxygenation may improve combined exercise and EF performance.NEW & NOTEWORTHY The executive functioning aspect of cognition was evaluated during graded exercise in Reserve Officers' Training Corps cadets. Executive function declined at exercise intensities of ≥80% of heart rate reserve. The decline in executive function was coupled with declines in the oxygenation of the prefrontal cortex, the brain region responsible for executive functioning. These data define the executive function-exercise intensity relationship and provide evidence supporting the reticular activation hypofrontality theory as a model of cognitive change.

Can Acupuncture Treatment of Hypertension Improve Brain Health? A Mini Review.

With age, cerebrovascular and neurodegenerative diseases (e.g., dementia and Alzheimer's) are some of the leading causes of death in the United States. Related to these outcomes is the increased prevalence of hypertension, which independently increases the development of cerebrovascular and neurodegenerative diseases. While a direct mechanistic link between hypertension and poor brain health is unknown, many hypothesize that the etiology stems from poor blood pressure (BP) and cerebrovascular regulation. This dysfunction fosters hypoperfusion of the brain, causing stress to the tissue through a nutrient mismatch, subtly damaging the brain over many years. Current Western medical treatment relies on pharmacological treatment (mainly beta-blockers, angiotensin-converting enzyme inhibitors, or a combination of the two). However, Western treatments have not been successful in mitigating brain health outcomes and are burdened with unwanted side effects and non-adherence issues. Alternatively, traditional East Asia medicine has used acupuncture as a treatment for hypertension and may offer a promising approach in response to the limitations of conventional therapy. While detailed clinical and mechanistic experimental evidence is lacking, acupuncture has been observed to reduce BP and improve endothelial function in hypertensive adults. Further, acupuncture has been shown to have specific cerebrovascular effects, increasing cerebrovascular reactivity in healthy adults, highlighting possible neuroprotective properties. Therefore, our review is aimed at evaluating acupuncture as a treatment for hypertension and the potential impact on brain health. We will interrogate the current literature as well as discuss the proposed neural and vascular mechanisms by which acupuncture acts.

Impact of l-citrulline supplementation on oxygen uptake kinetics during walking.

Supplementation with l-citrulline (Cit) has been shown to improve muscle oxygenation and oxygen uptake kinetics during moderate- to high-intensity cycling in young men. The aim of this study was to test the hypothesis that Cit would improve oxygen uptake kinetics during walking in older and young adults. In a randomized, double-blind study, 26 (15 women, 11 men) adults between the ages of 20-35 years (n = 15) and 64-86 years (n = 11) completed 7-day periods of taking placebo and Cit (6 g/day) in a crossover manner. Participants walked on a treadmill at 40% heart rate reserve while pulmonary oxygen uptake was measured using indirect calorimetry. Net oxygen cost, mean response time (MRT), and the oxygen deficit were calculated before and after each supplement period. There was no significant change (P > 0.05) in net oxygen cost, MRT, or the oxygen deficit after Cit in older adults, while young adults showed a decrease (P = 0.05) in the oxygen deficit after Cit that tended (P = 0.053) to be different than the change after placebo. Sex-stratified analysis revealed that Cit decreased MRT (P = 0.04, Cohen's d = 0.41) and the oxygen deficit (P < 0.01, Cohen's d = 0.56) in men with the change after Cit being greater than the change after placebo (MRT: -4.5 ± 2.1 vs. 3.4 ± 2.1 s, P = 0.01; deficit: -0.15 ± 0.05 vs. 0.01 ± 0.05 L, P = 0.02). All oxygen uptake parameters were unchanged (P > 0.05) following Cit and placebo in women. Cit does not alter the oxygen cost of moderate-intensity walking in young or older adults, but Cit improved the rate of rise in oxygen uptake at exercise onset in men.

Does l-citrulline supplementation improve exercise blood flow in older adults?

NEW FINDINGS: What is the central question of this study? Does short-term supplementation with l-citrulline in order to increase l-arginine improve exercise blood flow and peripheral dilatation responses to exercise in older adults? What is the main finding and its importance? l-Citrulline increased femoral blood flow by 11% and vascular conductance by 14% during lower-limb exercise in older men, whereas no changes were observed in older women. This modest improvement in bulk muscle blood flow in older men has implications for altering muscle metabolism that may result in enhanced exercise tolerance in older adults. l-Citrulline (Cit) increases l-arginine (Arg), the primary substrate for nitric oxide biosynthesis. We tested the hypothesis that muscle blood flow during exercise would be enhanced by Cit supplementation in older adults. Femoral artery blood flow was measured during calf exercise using Doppler ultrasound, and vascular conductance (FVC) was calculated in 25 older adults (13 women and 12 men) before and after 14 days of Cit (6 g day-1 ) and placebo (maltodextrin) in a randomized, double-blind, crossover study. Plasma [Arg] and resting blood pressure were also measured before and after each condition. Women and men were analysed separately because of significant sex-by-condition interactions for the change in exercise blood flow and FVC. Plasma [Arg] was increased by 30 and 35% after Cit (P < 0.01) in women and men, respectively, with no change after placebo. Citrulline lowered diastolic blood pressure in men (75 ± 9 versus 71 ± 6 mmHg, P = 0.02), but this variable remained unchanged in women. Blood flow and FVC during exercise at higher workloads were increased after Cit in men (flow, 521 ± 134 versus 584 ± 166 ml min-1 , P = 0.04; FVC, 5.0 ± 1.5 versus 5.8 ± 1.7 m, min mmHg-1 , P = 0.01) but were not different after placebo. These variables were not altered by Cit in women. Adjusting for baseline diastolic blood pressure removed (P = 0.10) the difference in FBF and FVC following Cit in men. These results indicate that l-citrulline has a modest effect of improving muscle blood flow during submaximal exercise in older men.

Effect of UV Light on Disinfection of Peritoneal Dialysis Catheter Connections.

We evaluated the microbiological performance of an ultraviolet (UV) light-based peritoneal dialysis catheter connection system. The system includes a UV light-generating device combined with a UV transmissive window incorporated into the transfer set. Each UV transparent transfer set was inoculated with 10 µL of cultured inoculum consisting of either S. aureus, E. coli, or C. albicans After being inoculated, we attached a solution set connector to the transfer catheter, and exposed that connection to a UV light dose of approximately 340 mJoules/cm2 After exposure to UV light, we broke the seal of the solution set and opened the plunger valve on the UV transmissive transfer catheter. We then flushed 10 mL of dialysate through the connection. The flushed solution was collected, diluted, plated on agar medium, and incubated for 24 hours. Results were compared to positive controls collected in an identical manner without exposure to UV light. Thirty test samples and 3 positive controls were collected for each organism. All test samples exposed to UV light had complete kill of bacteria except 1 colony on a single plate in the S. aureus group. Mean log reduction was 4.03 for C. albicans, 4.73 for S. aureus, and 5.29 for E. coli All positive control samples had significant bacterial growth. Our results demonstrate that the application of UV light within a UV transmissive transfer catheter window produces a germicidal effect upon microorganisms known to be associated with peritonitis.

Love 2.0: a quantitative exploration of sex and relationships in the virtual world Second Life.

This study presents the quantitative results of a web-based survey exploring the experiences of those who seek sex and relationships in the virtual world of Second Life. The survey gathered data on demographics, relationships, and sexual behaviors from 235 Second Life residents to compare with U.S. General Social Survey data on Internet users and the general population. The Second Life survey also gathered data on interests in and experiences with a number of sexual practices in both offline and online environments. Comparative analysis found that survey participants were significantly older, more educated, and less religious than a wider group of Internet users, and in certain age groups were far less likely to be married or have children. Motivations for engaging in cybersex were presented. Analysis of interest and experience of different sexual practices supported findings by other researchers that online environments facilitated access, but also indicated that interest in certain sexual practices could differ between offline and online environments.

Alignment of multi-layered muscle cells within three-dimensional hydrogel macrochannels.

This work describes the development and testing of poly(ethylene glycol) (PEG) hydrogels with independently controlled dimensions of wide and deep macrochannels for their ability to promote alignment of skeletal myoblasts and myoblast differentiation. A UV-photopatterned thiol-ene mold was employed to produce long channels, which ranged from ∼40 to 200 µm in width and from ∼100 to 200 µm in depth, within a PEG-RGD hydrogel. Skeletal myoblasts (C2C12) were successfully cultured multiple cell layers deep within the channels. Decreasing channel width, increasing channel depth and, interestingly, increasing cell layer away from the channel base all contributed to a decreased interquartile range of cell angle relative to the long axis of the channel wall, indicating improved cell alignment. Differentiation of skeletal myoblasts into myotubes was confirmed by gene expression for myoD, myogenin and MCH IIb, and myotube formation for all channel geometries, but was not dependent on channel size. Qualitatively, myotubes were characteristically different, as myotubes were larger and had more nuclei in larger channels. Overall, our findings demonstrate that relatively large features, which do not readily facilitate cell alignment in two dimensions, promote cell alignment when presented in three dimensions, suggesting an important role for three-dimensional spatial cues.

Soft-lithography fabrication of microfluidic features using thiol-ene formulations.

In this work, a novel thiol-ene based photopolymerizable resin formulation was shown to exhibit highly desirable characteristics, such as low cure time and the ability to overcome oxygen inhibition, for the photolithographic fabrication of microfluidic devices. The feature fidelity, as well as various aspects of the feature shape and quality, were assessed as functions of various resin attributes, particularly the exposure conditions, initiator concentration and inhibitor to initiator ratio. An optical technique was utilized to evaluate the feature fidelity as well as the feature shape and quality. These results were used to optimize the thiol-ene resin formulation to produce high fidelity, high aspect ratio features without significant reductions in feature quality. For structures with aspect ratios below 2, little difference (<3%) in feature quality was observed between thiol-ene and acrylate based formulations. However, at higher aspect ratios, the thiol-ene resin exhibited significantly improved feature quality. At an aspect ratio of 8, raised feature quality for the thiol-ene resin was dramatically better than that achieved by using the acrylate resin. The use of the thiol-ene based resin enabled fabrication of a pinched-flow microfluidic device that has complex channel geometry, small (50 µm) channel dimensions, and high aspect ratio (14) features.

Prediction of an HLA-DR-binding peptide derived from Wilms' tumour 1 protein and demonstration of in vitro immunogenicity of WT1(124-138)-pulsed dendritic cells generated according to an optimised protocol.

The Wilms' tumour 1 (WT1) protein is over-expressed in several types of cancer including leukaemias and might therefore constitute a novel target for immunotherapy. Recently, human leucocyte antigen (HLA) class I-binding WT1 peptides have been identified and shown to stimulate CD8(+) T cells in vitro. For maximal CD8 cell efficacy, CD4(+) helper T cells responding to major histocompatibility complex (MHC) class II-binding epitopes are required. Here, we report that scanning the WT1 protein sequence using an evidence-based predictive computer algorithm (SYFPEITHI) yielded a peptide WT1(124-138) predicted to bind the HLA-DRB1*0401 molecule with high affinity. Moreover, synthetic WT1(124-138)-peptide-pulsed dendritic cells (DC), generated according to a protocol optimised in the present study, sensitised T cells in vitro to proliferate and secrete interferon-gamma (IFN-gamma) when rechallenged with specific peptide-pulsed DC, but not with peripheral blood mononuclear cells (PBMC). These results suggest that the WT1 protein may yield epitopes immunogenic to CD4 as well as CD8 T cells, and therefore constitute a novel potential target for specific immunotherapy.