429 research outputs found
Deep Learning to Automatically Interpret Images of the Electrocardiogram: Do We Need the Raw Samples?
Prenatal Exposure to Bisphenol A at Environmentally Relevant Doses Adversely Affects the Murine Female Reproductive Tract Later in Life
Born to yawn? Understanding yawning as a warning of the rise in cortisol levels: Randomized trial
Background: Yawning consistently poses a conundrum to the medical profession and neuroscientists. Despite neurological evidence such as parakinesia brachialis oscitans in stroke patients and thermo-irregulation in multiple sclerosis patients, there is considerable debate over the reasons for yawning with the mechanisms and hormonal pathways still not fully understood. Cortisol is implicated during yawning and may link many neurological disorders. Evidence was found in support of the Thompson cortisol hypothesis that proposes cortisol levels are elevated during yawning just as they tend to rise during stress and fatigue. Objectives: To investigate whether saliva cortisol levels rise during yawning and, therefore, support the Thompson cortisol hypothesis. Methods: We exposed 20 male and female volunteers aged between 18 and 53 years to conditions that provoked a yawning response in a randomized controlled trial. Saliva samples were collected at the start and again after the yawning response, or at the end of the stimuli presentations if the participant did not yawn. In addition, we collected electromyographic data of the jaw muscles to determine rest and yawning phases of neural activity. Yawning susceptibility scale, Hospital Anxiety and Depression Scale, General Health Questionnaire, and demographic and health details were also collected from each participant. A comprehensive data set allowed comparison between yawners and nonyawners, as well as between rest and yawning phases. Collecting electromyographic data from the yawning phase is novel, and we hope this will provide new information about neuromuscular activity related to cortisol levels. Exclusion criteria included chronic fatigue, diabetes, fibromyalgia, heart conditions, high blood pressure, hormone replacement therapy, multiple sclerosis, and stroke. We compared data between and within participants. Results: In the yawning group, there was a significant difference between saliva cortisol samples (t = -3.071, P = .01). Power and effect size were computed based on repeated-measures t tests for both the yawning and nonyawning groups. There was a medium effect size for the nonyawners group (r = .467) but low power (36%). Results were similar for the yawners group: medium effect size (r = .440) and low power (33%). Conclusions: There was significant evidence in support of the Thompson cortisol hypothesis that suggests cortisol levels are elevated during yawning. A further longitudinal study is planned to test neurological patients. We intend to devise a diagnostic tool based on changes in cortisol levels that may assist in the early diagnosis of neurological disorders based on the data collected. Trial Registration: International Standard Randomized Controlled Trial Number (ISRCTN): 61942768; http://www.controlled-trials.com/ISRCTN61942768/61942768 (Archived by WebCite at http://www.webcitation.org/6A75ZNYvr)
The reliability of a breathâhold protocol to determine cerebrovascular reactivity in adolescents
This is the published version. Available on open access from Wiley via the DOI in this recordPurpose
Cerebrovascular reactivity (CVR) is impaired in adolescents with cardiovascular disease risk factors. A breathâhold test is a noninvasive method of assessing CVR, yet there are no reliability data of this outcome in youth. This study aimed to assess the reliability of a breathâhold protocol to measure CVR in adolescents.
Methods
Twentyâone 13 to 15âyear old adolescents visited the laboratory on two separate occasions, to assess the withinâtest, withinâday and betweenâday reliability of a breathâhold protocol, consisting of three breathâhold attempts. CVR was defined as the relative increase from baseline in middle cerebral artery mean blood velocity following a maximal breathâhold of up to 30âseconds, quantified via transcranial Doppler ultrasonography.
Results
Mean breathâhold duration and CVR were never significantly correlated (r â.08). The withinâtest coefficient of variation for CVR was 15.2%, with no significant differences across breathâholds (P =â.88), so the three breathâhold attempts were averaged for subsequent analyses. The withinâ and betweenâday coefficients of variation for CVR were 10.8% and 15.3%, respectively.
Conclusions
CVR assessed via a three breathâhold protocol can be reliably measured in adolescents, yielding similar withinâ and betweenâday reliability. Analyses revealed that breathâhold length and CVR were unrelated, indicating the commonly reported normalization of CVR to breathâhold duration (breathâhold index) may be unnecessary in youth
The acute and postprandial effects of sugar moiety on vascular and metabolic health outcomes in adolescents
This is the author accepted manuscript. The final version is available from Canadian Science Publishing via the DOI in this recordThis study explored the cardiometabolic responses to sugar moieties acutely, and following a
subsequent mixed meal tolerance test (MMTT). Twenty-one healthy adolescents (N=10
female, 14.3±0.4 years) completed three experimental and one control condition, in a
counterbalanced order. These consisted of different drinks to compare the effect of 300 mL of
water (control), or 300 mL of water mixed with 60 g of glucose, fructose or sucrose, on vascular
function (flow-mediated dilation; FMD, microvascular reactivity (total hyperaemic response;
TRH); and cerebrovascular reactivity; CVR), and blood samples for [uric acid], [glucose],
[triglycerides] and [lactate]. FMD increased 1 hour after glucose and sucrose (P<0.001,
ESâ„0.92) but was unchanged following fructose and water (P>0.19, ES>0.09). CVR and TRH
were unchanged 1 hour following all conditions (P>0.57, ES>0.02). Following the MMTT, FMD
was impaired in all conditions (P0.40) with no differences between conditions
(P>0.13, ES<0.39). Microvascular TRH was increased in all conditions (P=0.001, ES=0.88),
and CVR was preserved in all conditions post MMTT (P=0.87, ES=0.02). Blood [uric acid] was
elevated following fructose consumption and the MMTT (P0.40). Consumption of a
sugar sweetened beverage did not result in vascular dysfunction in healthy adolescents,
however the vascular and metabolic responses were dependent on sugar moiety
The Weak Gravity Conjecture and the Viscosity Bound with Six-Derivative Corrections
The weak gravity conjecture and the shear viscosity to entropy density bound
place constraints on low energy effective field theories that may help to
distinguish which theories can be UV completed. Recently, there have been
suggestions of a possible correlation between the two constraints. In some
interesting cases, the behavior was precisely such that the conjectures were
mutually exclusive. Motivated by these works, we study the mass to charge and
shear viscosity to entropy density ratios for charged AdS5 black branes, which
are holographically dual to four-dimensional CFTs at finite temperature. We
study a family of four-derivative and six-derivative perturbative corrections
to these backgrounds. We identify the region in parameter space where the two
constraints are satisfied and in particular find that the inclusion of the
next-to-leading perturbative correction introduces wider possibilities for the
satisfaction of both constraints.Comment: 24 pages, 6 figures, v2: published version, refs added, minor
clarificatio
Oral Exposure to Genistin, the Glycosylated Form of Genistein, during Neonatal Life Adversely Affects the Female Reproductive System
Three-dimensional performance surfacesâa tool for analysing and estimation of production system performances
Quintessence-the Dark Energy in the Universe?
Quintessence - the energy density of a slowly evolving scalar field - may
constitute a dynamical form of the homogeneous dark energy in the universe. We
review the basic idea and indicate observational tests which may distinguish
quintessence from a cosmological constant.Comment: 13 pages, 3 figures, LaTe
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