Evidence regarding the impact of menstrual phase on endothelial function is conflicting, and studies to date have examined responses only over a single cycle.It is unknown whether the observed inter-individual variability of phase changes in endothelial function reflects stable, inter-individual differences in responses to oestrogen (E 2 ; a primary female sex hormone). The purpose of this study was to examine changes in endothelial function from the early follicular (EF; low-E 2 ) phase to the late follicular (LF; high-E 2 ) phase over two consecutive cycles. Fourteen healthy, regularly menstruating women [22 ± 3 years of age (mean ± SD)] participated in four visits (EF Visit 1 , LF Visit 2 , EF Visit 3 and LF Visit 4 ) over two cycles. Ovulation testing was used to determine the time between the LF visit and ovulation. During each visit, endothelial function [brachial artery flow-mediated dilatation (FMD)], E 2 and progesterone were assessed. At the group level, there was no impact of phase or cycle on FMD (P = 0.48 and P = 0.65, respectively). The phase change in FMD in cycle 1 did not predict the phase change in cycle 2 (r = 0.03, P = 0.92). Using threshold-based classification (2 × typical error threshold), four of 14 participants (29%) exhibited directionally consistent phase changes in FMD across cycles. Oestrogen was not correlated between cycles, and this might have contributed to variability in the FMD response. The intra-individual variability in follicular fluctuation in FMD between menstrual cycles challenges the utility of interpreting individual responses to phase over a single menstrual cycle.
Passive leg movement-elicited hyperaemia (PLM-H) provides an index of lower-limb microvascular function. However, there is currently limited information regarding the reliability of PLM-H and no reliability information specific to women. The purpose of this study was to determine the reliability of PLM-H in women on two separate days. Seventeen young, healthy women [22 ± 3 years old (mean ± SD)] participated in two identical visits including three trials of PLM. Using duplex ultrasound, PLM-H was characterized by six indices: peak leg blood flow (LBF) and vascular conductance (LVC), peak change above baseline (Δpeak) for LBF and LVC, and area under the curve above baseline (AUC) during the first 60 s of PLM for LBF and LVC. The results demonstrated good day-to-day reliability of PLM-H characterized as peak LBF [r = 0.84, P < 0.001; intraclass correlation coefficient (ICC) = 0.84; coefficient of variation (CV) = 13.2%],
Introduction MicroRNAs (miRNAs) have been shown to be altered in both CVD and T2DM and can have an application as diagnostic and prognostic biomarkers. miRNAs are released into circulation when the cardiomyocyte is subjected to injury and damage. Objectives Measuring circulating miRNA levels in human plasma may be of great potential use for measuring the extent of damage to cardiomyocytes and response to exercise. This review is aimed to highlight the potential application of miRNAs as biomarkers of CVD progression in T2DM, and the impact of exercise on recovery. Methods The review aims to examine whether the health improvements following exercise in T2DM patients are reflective of changes in expression of plasma miRNAs. For this purpose, studies were identified from the literature that have established a correlation between diabetes, disease progression and plasma miRNA levels. We also reviewed studies which looked at the effect of exercise on plasma miRNA levels. Results The review identified miRNA signatures that are affected by T2DM and DHD and a subset of these miRNAs that are also affected by different types of exercise. This approach helped us to identify those miRNAs whose expression and function can be altered by regular bouts of exercise. Conclusions miRNAs identified as part of this review can serve as tools to monitor the cardio-protective, anti-inflammatory and metabolic effects of exercise in people suffering from T2DM. Future research should focus on regulation of these miRNAs in T2DM and how they can be altered by appropriate exercise interventions.
Age‐related decrements in systemic arterial health may be indicative of alterations in cerebral perfusion and structure that are implicated in neurocognitive impairment. Purpose To determine if indicators of systemic arterial health are related to hemodynamic and structural changes in the brain in a population of healthy young and old adults. Hypothesis Poorer markers of arterial health will be associated with aging‐related hemodynamic and structural changes in the brain. Methods Young (n=13, f=7, m=6, 24±3 y, 71±18 kg) and old (n=14, f=5, m=9, 71±4 y, 83±15 kg) participants completed two experimental visits. In visit 1, systemic arterial health was assessed using carotid‐to‐femoral pulse wave velocity (PWV; indicator of central arterial stiffness; tonometry), left common carotid artery intima media thickness (IMT; indicator of carotid health; B‐mode Doppler Ultrasound), and brachial artery flow‐mediated dilation (FMD; indicator of peripheral endothelial function; duplex ultrasound). In visit 2, structural and arterial spin‐labelling neuroimaging data were acquired for computation of grey matter volume (GMV; indicator for structural integrity of the cortical tissues) and baseline cerebral blood flow (CBF0; indicator of gray matter vascular tone and perfusion). Between group differences were assessed using a two‐tailed, unpaired t‐test. Multiple linear regression analysis was used to model the relationship between indices of peripheral arterial function (PWV, IMT and FMD) and age with hemodynamic (CBF0) and structural (GMV) indices of brain health. Results PWV and IMT were greater in old vs. young adults (p<0.01). Reductions in FMD in the older adults approached significance (p=0.06). Both CBF0 and GMV were significantly lower in old vs. young adults (p<0.01). The dependent variable CBF 0 could be predicted from a linear combination (R2=0.72) of the independent variables age (p<0.01), PWV (p=0.04), FMD (p=0.04) and the contribution from IMT approached significance (p=0.07). The dependent variable GMV could be predicted by age alone (R2=0.74, p<0.01; all other variables p≥0.49). To isolate the relationship between indices of arterial health and brain structure, the regression analysis was repeated with age excluded. The dependent variable GMV could be predicted by IMT alone (R2=0.56, p<0.01) with the contribution from PWV approaching significance (p=0.10; FMD, p=0.83). Conclusion These data indicate that in a population of healthy young and old adults, decreased systemic arterial health is associated with hemodynamic and structural deficits in the brain. Support or Funding Information This work was supported by an Alzheimer’s Society of Brant, Haldimand Norfolk, Hamilton Halton award to REK MacPherson. TD Olver is supported by the Saskatchewan Health Research Foundation Establishment Grant #4522.
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