Health Disparities and COVID-19 Pandemic: Increasing Clinical Research Participation among African Americans

Health disparities in African Americans is a persistent issue. Higher rates and severity of the novel coronavirus-19 [COVID-19] among African Americans only widens health disparities. Effective COVID-19 treatment options are imperative, requiring representation of African Americans in clinical research. However, low participation and under-representation of African Americans is complex in nature. This article describes health disparities, the impact of COVID-19, and participation in clinical research among African Americans. We offer strategies for researchers to enhance the inclusion of African Americans. We also offer strategies in conducting clinical research during COVID-19

Differential Post-Exercise Blood Pressure Responses between Blacks and Caucasians

Post-exercise hypotension (PEH) is widely observed in Caucasians (CA) and is associated with histamine receptors 1- and 2- (H1R and H2R) mediated post-exercise vasodilation. However, it appears that blacks (BL) may not exhibit PEH following aerobic exercise. Hence, this study sought to determine the extent to which BL develop PEH, and the contri- bution of histamine receptors to PEH (or lack thereof) in this population. Forty-nine (22 BL, 27 CA) young and healthy subjects completed the study. Subjects were randomly assigned to take either a combined H1R and H2R antagonist (fexofenadine and ranitidine) or a con- trol placebo. Supine blood pressure (BP), cardiac output and peripheral vascular resistance measurements were obtained at baseline, as well as at 30 min, 60 min and 90 min after 45 min of treadmill exercise at 70% heart rate reserve. Exercise increased diastolic BP in young BL but not in CA. Post-exercise diastolic BP was also elevated in BL after exercise with histamine receptor blockade. Moreover, H1R and H2R blockade elicited differential responses in stroke volume between BL and CA at rest, and the difference remained follow- ing exercise. Our findings show differential BP responses following exercise in BL and CA, and a potential role of histamine receptors in mediating basal and post-exercise stroke vol- ume in BL. The heightened BP and vascular responses to exercise stimulus is consistent with the greater CVD risk in BL

Sex differences in autonomic function following maximal exercise

Background: Heart rate variability (HRV), blood pressure variability, (BPV) and heart rate recovery (HRR) are measures that provide insight regarding autonomic function. Maximal exercise can affect autonomic function, and it is unknown if there are sex differences in autonomic recovery following exercise. Therefore, the purpose of this study was to determine sex differences in several measures of autonomic function and the response following maximal exercise. Methods: Seventy-one (31 males and 40 females) healthy, nonsmoking, sedentary normotensive subjects between the ages of 18 and 35 underwent measurements of HRV and BPV at rest and following a maximal exercise bout. HRR was measured at minute one and two following maximal exercise. Results: Males have significantly greater HRR following maximal exercise at both minute one and two; however, the significance between sexes was eliminated when controlling for VO2 peak. Males had significantly higher resting BPV-low-frequency (LF) values compared to females and did not significantly change following exercise, whereas females had significantly increased BPV-LF values following acute maximal exercise. Although males and females exhibited a significant decrease in both HRV-LF and HRV-high frequency (HF) with exercise, females had significantly higher HRV-HF values following exercise. Males had a significantly higher HRV-LF/HF ratio at rest; however, both males and females significantly increased their HRV-LF/HF ratio following exercise. Conclusions: Pre-menopausal females exhibit a cardioprotective autonomic profile compared to age-matched males due to lower resting sympathetic activity and faster vagal reactivation following maximal exercise. Acute maximal exercise is a sufficient autonomic stressor to demonstrate sex differences in the critical post-exercise recovery period

Effects of Aging and Physical Activity on Cardiovascular Responses to Acute, Induced Inflammation

Background: Aging is characterized by increased arterial and ventricular stiffness and systemic inflammation. This leads to a concomitant rise in both arterial elastance (Ea: total arterial load) and ventricular elastance (Elv: left ventricular contractility or stiffness). Their ratio (Ea/Elv) determines ejection fraction. Co-morbidities common in aged individuals transiently cause further up-regulation of inflammation. This may predispose older adults to cardiac events. Physically active older adults, however, retain a more compliant cardiovascular system, partially mediated by reduced systemic inflammation. Purpose and Hypothesis: This study investigated the effects of acute inflammation on cardiovascular (Ea and Elv), and endothelial function and blood pressure, in older versus younger adults. The association of physical activity and inflammation-induced cardiovascular changes were investigated. We hypothesized increased Ea/Elv that would be greater in older versus younger adults. We hypothesized that younger adults would have a larger decrement in endothelial function and lesser increase in blood pressure versus older adults, but that physical activity would protect both groups from these changes. Methods: End-systolic and central blood pressure were obtained using applanation tonometry before and at 24 and 48 hr after an influenza vaccination. Ultrasonography was used to measure cardiac volumes and other indices of performance. Ea=end-systolic pressure (ESP)/ stroke volume and Elv=ESP/end-systolic volume. Endothelial function was assessed using flow-mediated dilation. Physical activity was measured with accelerometry. Results: There was no change in Ea or Ea/Elv (p>0.05), but a reduction in Elv (p<0.05) in both older and younger adults. Systolic performance was reduced in older but not younger adults, while diastolic performance was attenuated in both groups at 24 hr post-inflammation (p<0.05 for all). Younger adults attenuated flow-mediated dilation at 24 and 48 hr post-inflammation and older adults did not, (p<0.05). Older adults decreased peripheral and central systolic pressure after inflammation, and younger adults did not, (p<0.05). Physical activity intensity was inversely related to the change in Elv at 24 hr post-vaccination, p<0.05. Conclusion: Aging does not affect the elastance response but does affect the blood pressure and endothelial responses to acute, induced inflammation. Physical activity was inversely related to the change in Elv following acute inflammation

Gravidity is not associated with telomere length in a biracial cohort of middle-aged women: The Coronary Artery Risk Development in Young Adults (CARDIA) study

<div><p>Objective</p><p>Having experienced 2–3 births is associated with reduced mortality versus women with <2 or ≥4 births. The effect of 2–3 births on lifespan may be associated with delayed cellular aging. We hypothesized telomere length, a marker of cellular aging, would be longer in women who had 2–3 pregnancies.</p><p>Methods</p><p>Leukocyte telomere length was measured using quantitative real-time polymerase chain reaction in 620 women in CARDIA at the year 15 and 20 exams, expressed as the ratio of telomere repeat copy number to single-copy gene copy number (<i>T</i>/<i>S</i>). Number of pregnancies at the time of telomere length measurement was obtained (mean age = 41±0.1 years, average gravidity = 2.64±0.1 pregnancies). Participants were divided into 4 groups by number of pregnancies: 0, 1, 2–3, and ≥4, to test for differences in telomere length by gravidity group.</p><p>Results</p><p>The mean and SD for telomere length was 0.98 ± 0.20 <i>T/S</i> in the whole cohort. There were no differences in mean telomere length between groups; 0.98±0.02 <i>T/S</i> in women with 0 pregnancies, 1.01±0.02 <i>T/S</i> in women with 1 pregnancy, 0.97±0.01 <i>T/S</i> in women with 2–3 pregnancies, and 0.99±0.02 <i>T/S</i> in women with ≥4 pregnancies (p = 0.51). We defined high-risk (shorter) telomere length as ≤25^th percentile, and low-risk (longer) telomere length as ≥75 percentile. There were no differences in the prevalence of high-risk or low-risk telomere length between gravidity groups.</p><p>Conclusions</p><p>Gravidity was not associated with telomere length in early middle age; the protective association of 2–3 births may act through other mechanisms.</p></div

Telomere length (mean and 95% CI) by gravidity group in Caucasian and African-American women.

<p>There were no differences in unadjusted telomere length between gravidity groups in either race.</p

Participant characteristics compared women not in sample.

<p>Participant characteristics compared women not in sample.</p

Participant characteristics at time of telomere length measurement by gravidity group.

<p>Participant characteristics at time of telomere length measurement by gravidity group.</p