Taking regular breaks from sitting prevents reductions in brain blood flow

Supplying the brain with enough blood flow is essential to keep us alive and maintain our brain health. Reductions in brain blood flow can negatively affect the ability to think. Decreased blood flow to the brain can also lead to brain diseases, such as dementia, which is a condition that causes permanent memory loss and confusion. Scientists are beginning to think that sitting may be bad for brain blood flow. Understanding how sitting affects the brain is therefore very important. We conducted a study in which participants either sat down without any breaks for 4 h, or sat down but took a short walking break every 30 min, or took a longer walking break every 2 h. After sitting without any breaks, brain blood flow decreased. However, when participants took a walking break every 30 min that prevented the decrease in brain blood flow. These results suggest we should encourage people to take regular breaks from sitting to help maintain brain health

Differences in Vascular Outcomes and Sedentary Behaviour in Pre- and Post-Menopausal Women

Introduction: Vascular ageing, characterized by endothelial dysfunction and atherosclerosis is an integral component of cardiovascular disease (CVD) development. The menopause and its associated reduction in oestrogen accelerates female vascular aging. Sedentary behaviour (SB) and physical activity (PA) levels modify vascular risk and may further exacerbate aging induced pathological arterial remodelling. The aim of this study was to examine the differences in vascular artery health, PA and SB in pre- and post-menopausal women. Methodology: Thirty-three female adults were recruited and grouped according to whether they were pre-menopausal (PRE-M; 31.410.7 years, BMI 24.76.7kg/m2) or post-menopausal (POST-M; 55.37.3 years, BMI 25.54.8kg/m2). Systolic (SBP) and diastolic (DBP) blood pressure was measured following 30 minutes supine rest. Vascular ultrasound was used to assess carotid artery intima media thickness (cIMT) and brachial artery vasodilator response to 5 minutes distal limb occlusion. Carotid artery reactivity (CAR%) to a cold pressor test was assessed and pulse wave velocity (PWV) was calculated using applanation tonometry. VO2max was determined by a cycling ramp protocol to volitional exhaustion. Habitual SB and PA were measured over 7 days using an inclinometer and accelerometry respectively. Group differences were determined using independent t-tests. Results: Significant differences (p=<0.01) were observed for SBP (107±7mmHg; 122±15mmHg), DBP (64±6mmHg; 70±6mmHg) and cIMT (0.58±0.07mm; 0.72±0.08mm) between PRE-M and POST-M women respectively. No significant differences were found between groups for PWV (PRE-M, 5.3±0.8cm/s; POST-M, 6.1±1.6cm/s) or CAR% (PRE-M; 1.56±2.4%, POST-M; 1.48±2.1%). VO2max was higher in PRE-M (35.8±6.7mL/kg/min; 25.3±4.8mL/kg/min; p<0.001). Neither total PA time (PRE-M; 265.4±72mins/d , POST-M; 317±93.2mins/d) nor daily SB differed significantly between groups (PRE-M, 65.5±16%; POST-M, 53.9±21.3%). Coclusion: Our findings confirm that SBP, DBP and cIMT increase with age. Despite a lower VO2max in POST-M, PA and SB patterns did not differ between PRE- and POST-M women. Our findings may indicate that VO2max, and not PA or SB level plays an important role in mediating some markers of vascular aging in post menopausal women, however further research is needed to confirm this

Fluctuation in Shear Rate, with Unaltered Mean Shear Rate, Improves Brachial Artery Flow-Mediated Dilation in Healthy, Young Men.

AIM: Increase in mean shear stress represents an important and potent hemodynamic stimulus to improve conduit artery endothelial function in humans. No previous study has examined whether fluctuations in shear rate patterns, without altering mean shear stress, impacts conduit artery endothelial function. This study examined the hypothesis that 30-minutes exposure to fluctuations in shear rate patterns, in the presence of unaltered mean shear rate, improves brachial artery flow-mediated dilation. METHODS: Fifteen healthy males (27.3±5.0 years) completed the study. Bilateral brachial artery flow-mediated dilation was assessed before and after unilateral exposure to 30-minutes of intermittent negative pressure (10seconds -40mmHg, 7seconds 0mmHg) to induce fluctuation in shear rate, whilst the contra-lateral arm was exposed to a resting period. RESULTS: Negative pressure significantly increased shear rate, followed by a decrease in shear rate upon pressure release (both P<0.001). Across the 30-minute intervention, mean shear rate was not different compared to baseline (P=0.458). A linear mixed model revealed a significant effect of time was observed for flow-mediated dilation (P=0.029), with exploratory post-hoc analysis showing an increase in the intervention arm (∆FMD +2.0%, P=0.008), but not in the contra-lateral control arm (∆FMD +0.5%, P=0.664). However, there was no effect for arm (P=0.619) or interaction effect (P=0.096). CONCLUSION: In conclusion, we found that fluctuations in shear patterns, with unaltered mean shear, improves brachial artery flow-mediated dilation. These novel data suggest that fluctuations in shear pattern, even in the absence of altered mean shear, represents a stimulus to acute change in endothelial function in healthy individuals

The Effect of Exercise During Pregnancy on Maternal and Offspring Vascular Outcomes: a Pilot Study

The aim of this pilot study is to obtain estimates for the change in maternal cerebrovascular (primary) and offspring vascular structure (secondary) during healthy pregnancy that includes structured exercise. Eighteen pregnant women self-assigned to a moderate-intensity aerobic exercise intervention or a control group. Maternal cerebral blood flow (CBF) at the middle cerebral artery, cerebro- and peripheral-vascular function was assessed at the end of each trimester. Offspring carotid artery intima-media thickness (IMT) was measured within 12 weeks of birth. For exploratory purposes, we performed statistical analysis to provide estimates of the change for primary and secondary outcome variables. Maternal CBF reduced (− 8 cm s−1 [− 14 to − 2]) with evidence of change to cerebral autoregulation (normalised gain: 0.12 %cm s−1 % mmHg−1 mmHg/% [− 0.18 to 0.40]) during pregnancy. Offspring carotid IMT was smaller in the exercise group (− 0.04 mm [− 0.12–0.03]) compared with controls. Based upon this data, a sample size of 33 and 57 in each group is required for low-frequency normalised gain and offspring IMT, respectively. This would provide 90% power to detect statistically significant (P < 0.05) between group differences in a randomised controlled trial. CBF is reduced in pregnancy, possibly due to reduced vascular resistance and altered maternal cerebral autoregulation. Maternal exercise had negligible effects on cerebrovascular adaptation to pregnancy, but we observed lower offspring carotid artery wall thickness following maternal exercise. Our directional findings and sample size estimations should be explored in a fully powered randomised control trial. Clinical trial registration: The trial was registered on March 14th at https://register.clinicaltrials.gov (NCT03079258). Participant enrolment began on 3rd April 2016. Keywords Pregnancy . Exercise . Cerebrovascular function . Endothelial function . Offsprin

Regular moderate intensity aerobic exercise does not affect vascular outcomes during pregnancy: A pilot study

Abstract. (Maximum of 250 words) Introduction: Cardiovascular diseases (CVD) are the leading cause of morbidity and mortality during pregnancy attributed to progressive vascular impairments. Regular exercise has been shown to improve vascular outcomes. The aim of this pilot study was to determine the impact of a 6-month exercise intervention on vascular outcomes in previously inactive pregnant women. Methods: Ten healthy pregnant women were recruited to a control (CONT; N=6 330.5 years, BMI 22.4kg/m2) or exercise group (EX; N=4 31.5 0.6 years, BMI 23.82.1kg/m2) at 13-15 weeks gestation. Ultrasound was used to assess brachial and femoral flow mediated dilation (bFMD; fFMD respectively) at the end of trimester 1(T1), 2(T2) and 3(T3). Aerobic capacity was estimated using the Astrand submaximal cycling protocol. Physical activity (PA) was measured over 7 days using accelerometry. The exercise intervention consisted of 3x15 minute weekly exercise sessions in trimester-2 (T2), progressing to 4x30 minutes in trimester-3 (T3). Data were analyzed for main effects of group and time using repeated measures ANOVA. Results: There were no time, group or interaction effects for BFMD (T1: 9.22.1%, T2:6.70.9%, T3: 95%, P=0.76), FFMD (T1, 6.53.4%, T2, 6.22%, T3, 2.41.9%, P=0.18). No differences in aerobic capacity were evident (T1, 47.4±5ml/kg, T2, 43.4±3.3ml/kg, T3, 39.1±3.5ml/kg, p=0.22). No differences were observed for physical activity (T1, 330±87mins/d; T2, 296±52mins/d; T3, 271±16mins/d. Conclusion: Our findings suggest that vascular outcomes are not impacted upon exercising during trimesters 2 and 3 of pregnancy. It is plausible that the hormonally induced hemodynamic adaptations which occur during pregnancy cannot be overridden by moderate intensity exercise

Adjusting bone mass for differences in projected bone area and other confounding variables: an allometric perspective.

The traditional method of assessing bone mineral density (BMD; given by bone mineral content [BMC] divided by projected bone area [Ap], BMD = BMC/Ap) has come under strong criticism by various authors. Their criticism being that the projected bone "area" (Ap) will systematically underestimate the skeletal bone "volume" of taller subjects. To reduce the confounding effects of bone size, an alternative ratio has been proposed called bone mineral apparent density [BMAD = BMC/(Ap)3/2]. However, bone size is not the only confounding variable associated with BMC. Others include age, sex, body size, and maturation. To assess the dimensional relationship between BMC and projected bone area, independent of other confounding variables, we proposed and fitted a proportional allometric model to the BMC data of the L2-L4 vertebrae from a previously published study. The projected bone area exponents were greater than unity for both boys (1.43) and girls (1.02), but only the boy's fitted exponent was not different from that predicted by geometric similarity (1.5). Based on these exponents, it is not clear whether bone mass acquisition increases in proportion to the projected bone area (Ap) or an estimate of projected bone volume (Ap)3/2. However, by adopting the proposed methods, the analysis will automatically adjust BMC for differences in projected bone size and other confounding variables for the particular population being studied. Hence, the necessity to speculate as to the theoretical value of the exponent of Ap, although interesting, becomes redundant

Regular walking breaks prevent the decline in cerebral blood flow associated with prolonged sitting.

Decreased cerebrovascular blood flow and function are associated with lower cognitive functioning and increased risk of neurodegenerative diseases. Prolonged sitting impairs peripheral blood flow and function, but its effects on the cerebrovasculature are unknown. This study explored the effect of uninterrupted sitting and breaking up sitting time on cerebrovascular blood flow and function of healthy desk workers. Fifteen participants (10 male, 35.8{plus minus}10.2 years, BMI: 25.5{plus minus}3.2 kg∙m-2) completed, on separate days, three 4-hr conditions in a randomised order: a) uninterrupted sitting (SIT), b) sitting with 2-min light intensity walking breaks every 30-min (2WALK) or c) sitting with 8-min light intensity walking breaks every 2-hrs (8WALK). At baseline and 4-hrs, middle cerebral artery blood flow velocity (MCAv), carbon dioxide reactivity (CVR) of the MCA and carotid artery were measured using transcranial Doppler (TCD) and duplex ultrasound respectively. Cerebral autoregulation (CA) was assessed with TCD using a squat-stand protocol and analysed to generate values of gain and phase in the very low, low, and high frequencies. There was a significant decline in SIT MCAv (-3.2{plus minus}1.2 cm.s-1) compared to 2WALK (0.6{plus minus}1.5 cm.s-1, p=0.02), but not between SIT and 8WALK (-1.2{plus minus}1.0 cm.s-1, p=0.14). For CA, the change in 2WALK very low frequency phase (4.47{plus minus}4.07 degrees) was significantly greater than SIT (-3.38{plus minus}2.82 degrees, p=0.02). There was no significant change in MCA or carotid artery CVR (p&gt;0.05). Results indicate that prolonged, uninterrupted sitting in healthy desk workers reduces cerebral blood flow, however this is offset when frequent, short-duration walking breaks are incorporated

A detailed phenotypic assessment of individuals affected by MFRP-related oculopathy

Purpose: To determine the spectrum of mutations and phenotypic variability within patients with mutations in membrane-type frizzled related protein gene (MFRP).Methods: Individuals were initially ascertained based on a phenotype similar to that previously published in association with MFRP mutations. Affected patients underwent a full ophthalmic examination (best-corrected visual acuity, slit-lamp examination, applanation tonometry, and fundoscopy), color fundus photography, optical coherence tomography, autofluorescence imaging, and electrophysiology. MFRP was identified by a genome-wide scan in the fourth-largest autozygous region in one consanguineous family. Sanger sequencing of all the exons and intron-exon boundaries of MFRP was undertaken in the affected individuals.Results: Seven affected individuals from four families were identified as having mutations in MFRP. Patients from two families were homozygous for mutations already previously described (c. 1143_1144 insC and c. 492 delC), while those from the other two were compound heterozygous for mutations (c. 201G>A and c. 491_492 insT, and c. 492 delC, and c. 1622_1625 delTCTG), three of which were novel. There was considerable phenotypic variability within and among families. Autofluorescence imaging revealed the central macula to be relatively well preserved. Foveal cysts and optic nerve head drusen were present in two of the four families. Electrophysiology results showed rod-cone dystrophy with mild to moderate reduction in macular function in all affected members.Conclusions: We report three novel MFRP mutations and expand the phenotypic data available on patients with MFRP mutations

The genomes of two key bumblebee species with primitive eusocial organization

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation

Effect of capping groups at the N- and C-termini on the conformational preference of α,β-peptoids

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