Reproducibility and diurnal variation of the directional sensitivity of the cerebral pressure-flow relationship in men and women

Author(s):  
Lawrence Labrecque ◽  
Joel S. Burma ◽  
Marc-Antoine Roy ◽  
Jonathan David Smirl ◽  
Patrice Brassard

The cerebral pressure-flow relationship has directional sensitivity, meaning the augmentation in cerebral blood flow is attenuated when mean arterial pressure (MAP) increases vs MAP decreases. We employed repeated squat-stands (RSS) to quantify it using a novel metric. However, its within-day reproducibility and the impacts of diurnal variation and biological sex are unknown. Study aims were to evaluate this metric for: 1) within-day reproducibility and diurnal variation in middle (MCA; ∆MCAvT/∆MAPT) and posterior cerebral arteries (PCA; ∆PCAvT/∆MAPT); 2) sex differences. ∆MCAvT/∆MAPT and ∆PCAvT/∆MAPT were calculated at seven time-points (08:00-17:00) in 18 participants (8 women; 24 ± 3 yrs) using the minimum-to-maximum MCAv or PCAv and MAP for each RSS at 0.05 Hz and 0.10 Hz. Relative metric values were also calculated (%MCAvT/%MAPT, %PCAvT/%MAPT). Intraclass correlation coefficient (ICC) evaluated reproducibility, which was good (0.75-0.90) to excellent (>0.90). Time-of-day impacted ∆MCAvT/∆MAPT (0.05 Hz: p = 0.002; 0.10 Hz: p = 0.001), %MCAvT/%MAPT (0.05 Hz: p = 0.035; 0.10 Hz: p = 0.009), and ∆PCAvT/∆MAPT (0.05 Hz: p = 0.024), albeit with small/negligible effect sizes. MAP direction impacted both arteries' metric at 0.10 Hz (all p < 0.024). Sex differences in the MCA only (p = 0.003) vanished when reported in relative terms. These findings demonstrate this metric is reproducible throughout the day in the MCA and PCA and is not impacted by biological sex.

2021 ◽  
Author(s):  
Lawrence Labrecque ◽  
Joel S. Burma ◽  
Marc-Antoine Roy ◽  
Jonathan D. Smirl ◽  
Patrice Brassard

We recently employed repeated squat-stands (RSS) to quantify directional sensitivity of the cerebral-pressure flow relationship (i.e. hysteresis) using a novel metric. Within-day reproducibility and diurnal variation impacts of this metric are unknown. We evaluated this metric for: 1) within-day reproducibility and the extent diurnal variation has in middle (MCA; ∆MCAvT/∆MAPT) and posterior cerebral arteries (PCA; ∆PCAvT/∆MAPT); 2) sex differences. Absolute (∆MCAvT/∆MAPT ; ∆PCAvT/∆MAPT) and relative (%MCAvT/%MAPT, %PCAvT/%MAPT) metrics were calculated at seven time-points (08:00-17:00) in 18 participants (8 women; 24 ± 3 yrs) using the minimum-to-maximum MCAv/PCAv and MAP for each RSS at 0.05 Hz and 0.10 Hz. Reproducibility was evaluated with intraclass correlation coefficient (ICC). For all metrics, reproducibility was good (0.75-0.90) to excellent (>0.90). The metric in both arteries was impacted by MAP direction at 0.10 Hz (all p < 0.024). Time-of-day influenced ∆MCAvT/∆MAPT (0.05 Hz: p = 0.0028; 0.10 Hz: p = 0.0009), %MCAvT/%MAPT (0.05 Hz: p = 0.035; 0.10 Hz: p = 0.0087), and ∆PCAvT/∆MAPT (0.05 Hz: p = 0.0236). Sex differences in the MCA (p = 0.0028) vanished in relative terms and was absent in the PCA. These findings demonstrate within-day reproducibility of this metric in both arteries. Moreover, hysteresis is not impacted by sex.


2020 ◽  
Vol 33 (2) ◽  
pp. 197-218
Author(s):  
Elaina M. Ross ◽  
Jeffrey A. Hall

AbstractTo account for sex differences in the production, receptivity, and preference for humor in potential mates during courtship, past research has often adopted an evolutionary approach. The present manuscript will attempt to integrate evolutionary explanations with proximal social and cultural influences using the traditional sexual script and ambivalent sexism theory. The results of both Study 1 (N=227) and Study 2 (N=424) suggest that trait masculinity is positively associated with humor production in courtship, while trait femininity is associated with humor receptivity. Study 1 indicated that the traditional flirting style was associated with less humor production by women, and Study 2 indicated that hostile sexism was related to a lower preference for a humor-producing potential partner by men. A sex difference in humor production in potential partners in Study 2 was no longer detectable once trait gender and hostile sexism was accounted for. Taken together, gender roles, over and above biological sex, influence one’s own humor use in courtship and preference for humor in potential partners.


SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A118-A118
Author(s):  
Gabriela Caetano ◽  
Laura Kervezee ◽  
Fernando Gonzales-Aste ◽  
Philippe Boudreau ◽  
Diane Boivin

Abstract Introduction National reports of work-related injuries found the excess risk of work injury attributed to shift work to be significantly higher among women. The Working Time Society (WTS) concluded that male sex is one of the few factors that is “consistently associated with perceived or actual shift work tolerance”. However, it is unclear if physiological parameters are involved. Laboratory-controlled studies report sex differences in circadian rhythms (body temperature, melatonin). In sleep deprivation protocols, alertness and cognitive performances were affected by sex, menstrual cycle phase and hormonal contraceptives [HC] use. Nevertheless, field studies that compare male and female shift workers are scarce. Methods An observational study including 76 police officers working on patrol: 56 males and 20 females (11 using [HC], 6 not using [non-HC] and 3 with unknown use of hormonal contraception) aged 32.0 ± 5.3 years. Participants were followed throughout a month-long work cycle (1,457 morning, evening, night, or other shifts, plus rest days). They filled out time-stamped questionnaires (Samn-Perelli, KSS, Visual Analogue Scales, ~5/day; sleep and work-related information, ~1–2/day), completed 5-min Psychomotor Vigilance Tasks (PVT, ~2/day), and wore an actigraph to collect activity data. Linear mixed-effects models were used to analyze the effects of group, time awake and time-of-day on fatigue, sleepiness, alertness, mood and PVT measures. Results Self-reported measures and psychomotor performance significantly varied with time awake and time-of-day. Fatigue and sleepiness levels were significantly higher among female compared to male police officers, both with time awake and across the 24-h day. These variations were similar between non-HC females and the other groups. Compared to males, HC females were more fatigued and less alert, both with time awake and across the 24-h day, and sleepier with time awake. Having children at home did not explain these differences. Conclusion The results of this study expand our knowledge on the sex differences in the sleep and circadian physiology and demonstrate a critical effect of HC on women fatigue, sleepiness and alertness when working shifts. Sex and hormonal parameters must be considered in occupational medicine as well as in future laboratory and field studies on shift workers and circadian rhythms. Support (if any) IRSST, FRQS.


Endocrinology ◽  
2022 ◽  
Author(s):  
Juyeun Lee ◽  
Katie Troike ◽  
R’ay Fodor ◽  
Justin D Lathia

Abstract Biological sex impacts a wide array of molecular and cellular functions that impact organismal development and can influence disease trajectory in a variety of pathophysiological states. In non-reproductive cancers, epidemiological sex differences have been observed in a series of tumors, and recent work has identified previously unappreciated sex differences in molecular genetics and immune response. However, the extent of these sex differences in terms of drivers of tumor growth and therapeutic response is less clear. In glioblastoma, the most common primary malignant brain tumor, there is a male bias in incidence and outcome, and key genetic and epigenetic differences, as well as differences in immune response driven by immune-suppressive myeloid populations, have recently been revealed. Glioblastoma is a prototypic tumor in which cellular heterogeneity is driven by populations of therapeutically resistant cancer stem cells (CSCs) that underlie tumor growth and recurrence. There is emerging evidence that GBM CSCs may show a sex difference, with male tumor cells showing enhanced self-renewal, but how sex differences impact CSC function is not clear. In this mini-review, we focus on how sex hormones may impact CSCs in GBM and implications for other cancers with a pronounced CSC population. We also explore opportunities to leverage new models to better understand the contribution of sex hormones versus sex chromosomes to CSC function. With the rising interest in sex differences in cancer, there is an immediate need to understand the extent to which sex differences impact tumor growth, including effects on CSC function.


2007 ◽  
Vol 7 (1) ◽  
pp. 211-222 ◽  
Author(s):  
M. Ehn ◽  
T. Petäjä ◽  
H. Aufmhoff ◽  
P. Aalto ◽  
K. Hämeri ◽  
...  

Abstract. The hygroscopic growth of aerosol particles present in a boreal forest was measured at a relative humidity of 88%. Simultaneously the gas phase concentration of sulfuric acid, a very hygroscopic compound, was monitored. The focus was mainly on days with new particle formation by nucleation. The measured hygroscopic growth factors (GF) correlated positively with the gaseous phase sulfuric acid concentrations. The smaller the particles, the stronger the correlation, with r=0.20 for 50 nm and r=0.50 for 10 nm particles. The increase in GF due to condensing sulfuric acid is expected to be larger for particles with initially smaller masses. During new particle formation, the changes in solubility of the new particles were calculated during their growth to Aitken mode sizes. As the modal diameter increased, the solubility of the particles decreased. This indicated that the initial particle growth was due to more hygroscopic compounds, whereas the later growth during the evening and night was mainly caused by less hygroscopic or even hydrophobic compounds. For all the measured sizes, a diurnal variation in GF was observed both during days with and without particle formation. The GF was lowest at around midnight, with a mean value of 1.12–1.24 depending on particle size and if new particle formation occurred during the day, and increased to 1.25–1.34 around noon. This can be tentatively explained by day- and nighttime gas-phase chemistry; different vapors will be present depending on the time of day, and through condensation these compounds will alter the hygroscopic properties of the particles in different ways.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Katja Linher-Melville ◽  
Anita Shah ◽  
Gurmit Singh

AbstractChronic pain occurs with greater frequency in women, with a parallel sexually dimorphic trend reported in sufferers of many autoimmune diseases. There is a need to continue examining neuro-immune-endocrine crosstalk in the context of sexual dimorphisms in chronic pain. Several phenomena in particular need to be further explored. In patients, autoantibodies to neural antigens have been associated with sensory pathway hyper-excitability, and the role of self-antigens released by damaged nerves remains to be defined. In addition, specific immune cells release pro-nociceptive cytokines that directly influence neural firing, while T lymphocytes activated by specific antigens secrete factors that either support nerve repair or exacerbate the damage. Modulating specific immune cell populations could therefore be a means to promote nerve recovery, with sex-specific outcomes. Understanding biological sex differences that maintain, or fail to maintain, neuroimmune homeostasis may inform the selection of sex-specific treatment regimens, improving chronic pain management by rebalancing neuroimmune feedback. Given the significance of interactions between nerves and immune cells in the generation and maintenance of neuropathic pain, this review focuses on sex differences and possible links with persistent autoimmune activity using sciatica as an example.


2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Eduardo Marcel Fernandes Nascimento ◽  
Diego Antunes ◽  
Paulo Cesar do Nascimento Salvador ◽  
Fernando Klitzke Borszcz ◽  
Ricardo Dantas de Lucas

Introduction. The purpose of this study was to evaluate the application of the Dmax method on heart rate variability (HRV) to estimate the lactate thresholds (LT), during a maximal incremental running test (MIRT). Methods. Nineteen male runners performed two MIRTs, with the initial speed at 8 km·h−1 and increments of 1 km·h−1 every 3 minutes, until exhaustion. Measures of HRV and blood lactate concentrations were obtained, and lactate (LT1 and LT2) and HRV (HRVTDMAX1 and HRVTDMAX2) thresholds were identified. ANOVA with Scheffe’s post hoc test, effect sizes (d), the bias ± 95% limits of agreement (LoA), standard error of the estimate (SEE), Pearson’s (r), and intraclass correlation coefficient (ICC) were calculated to assess validity. Results. No significant differences were observed between HRVTDMAX1 and LT1 when expressed for speed (12.1 ± 1.4 km·h−1 and 11.2 ± 2.1 km·h−1; p=0.55; d = 0.45; r = 0.46; bias ± LoA = 0.8 ± 3.7 km·h−1; SEE = 1.2 km·h−1 (95% CI, 0.9–1.9)). Significant differences were observed between HRVTDMAX2 and LT2 when expressed for speed (12.0 ± 1.2 km·h−1 and 14.1 ± 2.5 km·h−1; p=0.00; d = 1.21; r = 0.48; bias ± LoA = −1.0 ± 1.8 km·h−1; SEE = 1.1 km·h−1 (95% CI, 0.8–1.6)), respectively. Reproducibility values were found for the LT1 (ICC = 0.90; bias ± LoA = −0.7 ± 2.0 km·h−1), LT2 (ICC = 0.97; bias ± LoA = −0.1 ± 1.1 km·h−1), HRVTDMAX1 (ICC = 0.48; bias ± LoA = −0.2 ± 3.4 km·h−1), and HRVTDMAX2 (ICC = 0.30; bias ± LoA = 0.3 ± 3.5 km·h−1). Conclusions. The Dmax method applied over a HRV dataset allowed the identification of LT1 that is close to aerobic threshold, during a MIRT.


2002 ◽  
Vol 81 (10) ◽  
pp. 711-715 ◽  
Author(s):  
S. Yamada ◽  
S. Saeki ◽  
I. Takahashi ◽  
K. Igarashi ◽  
H. Shinoda ◽  
...  

Bone and cartilage metabolism is known to be more active during rest than during periods of activity. The purpose of this study was to examine the hypothesis that mandibular retractive force could be more effective when applied to rats during rest. Mandibular retractive force caused a considerable reduction in the condylar length in experimental groups, and the magnitude of this reduction was greater in the Light-period (08:00-20:00) group than in the Dark-period (20:00-08:00) group. The differentiation and proliferation of chondrocytes were inhibited in animals in the Light-period group, compared with those in the Dark-period group. These results suggest that the orthopedic effects of mandibular retractive force vary depending on the time of day the force is applied, and that such force may be more effective while animals are resting than while they are active.


2011 ◽  
Vol 300 (6) ◽  
pp. R1437-R1442 ◽  
Author(s):  
Helen Jones ◽  
Nia C. S. Lewis ◽  
Daniel J. Green ◽  
Philip N. Ainslie ◽  
Samuel J. E. Lucas ◽  
...  

Early morning reduction in endothelium-dependent, flow-mediated dilation (FMD) may contribute to the high incidence of sudden cardiac death at this time of day. The mechanisms underpinning diurnal variation in FMD are unclear, but potentially relate to a circadian rhythm in sympathetic nerve activity. We hypothesized that blockade of α1-mediated sympathetic nerve activity would act to attenuate the diurnal variation in FMD. In a randomized and placebo-controlled design, we measured brachial artery FMD in 12 participants (mean age = 26 yr, SD = 3) at 0600 and 1600 after ingestion of an α1-blocker (prazosin, 1 mg/20 kg body mass) or placebo. Arterial diameter and shear rate were assessed using edge-detection software. Heart rate and blood pressure were also measured. Data were analyzed using linear mixed modeling. Following placebo, FMD was 8 ± 2% in the morning compared with 10 ± 3% in the afternoon ( P = 0.04). Blockade with prazosin led to a slight but nonsignificant increase in morning FMD ( P = 0.24) and a significant ( P = 0.04) decrease in afternoon FMD, resulting in no diurnal variation ( P = 0.20). Shear rate did not differ in the morning or afternoon under either condition ( P > 0.23). Blood pressure was lower following prazosin compared with placebo ( P < 0.02), an effect that was similar at both times of day ( P > 0.34). Heart rate and norepinephrine levels were higher in the afternoon following prazosin. These data indicate that α1-adrenoreceptor activity does not explain lower morning endothelium-dependent FMD.


Neurology ◽  
2019 ◽  
Vol 93 (14 Supplement 1) ◽  
pp. S33.2-S34
Author(s):  
Nicholas Erdman, AT ◽  
Juliana Jimenez ◽  
David Howell ◽  
Thomas Buckley ◽  
Joseph Hart ◽  
...  

ObjectiveTo determine if biological sex influenced performance on a novel dual-task (DT) assessment which consisted of commonly used clinical measures of sport concussion (SC) in healthy college students.BackgroundDT assessments consist of motor and cognitive tasks administered simultaneously and show promise as clinical measures of SC.Design/MethodsOur cross-sectional study included 60 (53.3% female) healthy, recreationally active college students (age = 20.5 ± 1.34 years, height = 171.7 ± 9.33 cm, mass = 69.25 ± 12.23 kg). Participants completed the Standardized Assessment of Concussion (SAC) and timed tandem gait (TTG) test independently (single task [ST]) and concurrently (DT). The revised SAC (45 points) which included a 10-word list was utilized. The TTG composite score was a sum of the average time to completion for each SAC task (3 trials for immediate memory [10-word list], up to 5 trials for the digits-backwards task, and one trial for the months in reverse order and delayed recall tasks). Independent t-tests were used to assess for sex differences for SAC and TTG performance during ST and DT administration. 2 × 2 factorial analyses of variance (ANOVA) were used to assess for sex (male, female) by task (ST, DT) interaction effects with effect sizes calculated using Cohen’s d. All analyses were assessed at α = 0.05.ResultsNo sex differences were observed for ST performance of the SAC (males = 37.1 ± 3.45 points, females = 37.4 ± 3.74 points; t[58] = 0.28, p = 0.78) or TTG (males = 44.3 ± 7.09 seconds, females = 46.1 ± 8.88 seconds; t[58] = 0.88, p = 0.38). No sex differences were observed for DT performance of the SAC (males = 39.7 ± 4.50 points, females = 39.2 ± 3.12 points; t[58] = 0.46, p = 0.64) or TTG (males = 52.1 ± 8.56 seconds, females = 52.1 ± 10.28 seconds; t[58] = 0.02, p = 0.98). No sex by task interaction effects were observed for SAC (F = 0.74, p = 0.39, d = 0.23) or TTG (F = 1.1, p = 0.30, d = 0.28) performance for ST or DT assessment.ConclusionsOur results indicate that our novel DT assessment was robust to sex differences in healthy college students which supports the utilization of our DT assessment across sexes without adjustment for interpretation.


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