The antihypertensive influence of fish oil is controversial, and mechanisms remain unclear. We tested the hypothesis that fish oil reduces mean arterial pressure (MAP) via reductions in muscle sympathetic nerve activity (MSNA). Because the inverse relation between fish oil and hypertension appears to be dependent on the degree of hypertension, we also tested the hypothesis that fish oil would elicit more dramatic reductions in MAP and MSNA in prehypertensive (PHT) compared to normotensive (NT) subjects. Resting MAP, MSNA, and heart rate (HR) were examined before and after 8 wk of fish oil (9g/day) or placebo (olive oil; 9g/day) in 38 NT (19 fish oil; 19 placebo) and 29 PHT (15 fish oil; 14 placebo) volunteers. Fish oil did not alter resting MAP, MSNA, or HR in either NT (71±2 to 71±2 mmHg; 11±2 to 10±1 bursts/min; 80±1 to 80±1 beats/min) or PHT (88±2 to 87±1 mmHg; 11±2 to 10±2 bursts/min; 73±2 to 73±2 beats/min) subjects. However, when NT and PHT groups were consolidated, a significant correlation was observed between changes in MAP and changes in MSNA in the fish oil group (r=0.354, p=0.035). In conclusion, fish oil did not alter neural cardiovascular control in NT or PHT. However, interindividual MAP responses to fish oil appear to be moderately associated with changes in MSNA, suggesting that the sympathetic nervous system may contribute to the inconsistent antihypertensive response of fish oil. Supported by NIH (HL‐088689).
Fish oil and neurovascular reactivity to mental stress in humans
Omega‐3 fatty acids found in fish oil have been suggested to protect against cardiovascular disease, yet underlying mechanisms remain unclear. Given the well documented links between mental stress (MS) and cardiovascular risk, we hypothesized that fish oil would blunt blood pressure (BP), heart rate (HR), and muscle sympathetic nerve activity (MSNA) responsiveness to MS. Neural and cardiovascular responses to a 5 min mental arithmetic protocol were recorded in 67 non‐hypertensive subjects before and after 8 wks of fish oil (9g/day; n=33) or placebo (olive oil; 9g/day; n=34). Fish oil blunted HR reactivity to MS (group × condition × time interaction, P=0.012), but did not alter BP reactivity (interactions, P>;0.05). Fish oil blunted total MSNA reactivity to MS (interaction, P=0.039), but did not alter MSNA burst frequency and burst incidence reactivity (interactions, P>;0.05). Finally, fish oil significantly blunted calf vascular conductance (CVC) reactivity to MS (interaction, P=0.013), but did not alter forearm vascular conductance reactivity (interaction, P>;0.05). In conclusion, 8 wks of fish oil supplementation significantly attenuated HR and total MSNA reactivity to MS, and elicited a paradoxical blunting of CVC. These findings support and extend the growing evidence that fish oil may have positive health benefits regarding neural cardiovascular control in humans. Supported by NIH (HL‐088689).
Global Differences in Heart Failure With Preserved Ejection Fraction
Background: Heart failure with preserved ejection fraction (HFpEF) is a global public health problem with important regional differences. We investigated these differences in the PARAGON-HF trial (Prospective Comparison of Angiotensin Receptor Neprilysin Inhibitor With Angiotensin Receptor Blocker Global Outcomes in HFpEF), the largest and most inclusive global HFpEF trial. Methods: We studied differences in clinical characteristics, outcomes, and treatment effects of sacubitril/valsartan in 4796 patients with HFpEF from the PARAGON-HF trial, grouped according to geographic region. Results: Regional differences in patient characteristics and comorbidities were observed: patients from Western Europe were oldest (mean 75±7 years) with the highest prevalence of atrial fibrillation/flutter (36%); Central/Eastern European patients were youngest (mean 71±8 years) with the highest prevalence of coronary artery disease (50%); North American patients had the highest prevalence of obesity (65%) and diabetes (49%); Latin American patients were younger (73±9 years) and had a high prevalence of obesity (53%); and Asia-Pacific patients had a high prevalence of diabetes (44%), despite a low prevalence of obesity (26%). Rates of the primary composite end point of total hospitalizations for HF and death from cardiovascular causes were lower in patients from Central Europe (9 per 100 patient-years) and highest in patients from North America (28 per 100 patient-years), which was primarily driven by a greater number of total hospitalizations for HF. The effect of treatment with sacubitril-valsartan was not modified by region (interaction P >0.05). Conclusions: Among patients with HFpEF recruited worldwide in PARAGON-HF, there were important regional differences in clinical characteristics and outcomes, which may have implications for the design of future clinical trials. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01920711.
Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)
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Background: To describe the baseline characteristics of patients with heart failure and preserved left ventricular ejection fraction enrolled in the PARAGON-HF trial (Prospective Comparison of Angiotensin Receptor Neprilysin Inhibitor With Angiotensin Receptor Blocker Global Outcomes in HFpEF) comparing sacubitril/valsartan to valsartan in reducing morbidity and mortality. Methods and Results: We report key demographic, clinical, and laboratory findings, and baseline therapies, of 4822 patients randomized in PARAGON-HF, grouped by factors that influence criteria for study inclusion. We further compared baseline characteristics of patients enrolled in PARAGON-HF with those patients enrolled in other recent trials of heart failure with preserved ejection fraction (HFpEF). Among patients enrolled from various regions (16% Asia-Pacific, 37% Central Europe, 7% Latin America, 12% North America, 28% Western Europe), the mean age of patients enrolled in PARAGON-HF was 72.7±8.4 years, 52% of patients were female, and mean left ventricular ejection fraction was 57.5%, similar to other trials of HFpEF. Most patients were in New York Heart Association class II, and 38% had ≥1 hospitalizations for heart failure within the previous 9 months. Diabetes mellitus (43%) and chronic kidney disease (47%) were more prevalent than in previous trials of HFpEF. Many patients were prescribed angiotensin-converting enzyme inhibitors or angiotensin receptor blockers (85%), β-blockers (80%), calcium channel blockers (36%), and mineralocorticoid receptor antagonists (24%). As specified in the protocol, virtually all patients were on diuretics, had elevated plasma concentrations of N-terminal pro-B-type natriuretic peptide (median, 911 pg/mL; interquartile range, 464–1610), and structural heart disease. Conclusions: PARAGON-HF represents a contemporary group of patients with HFpEF with similar age and sex distribution compared with prior HFpEF trials but higher prevalence of comorbidities. These findings provide insights into the impact of inclusion criteria on, and regional variation in, HFpEF patient characteristics. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov . Unique identifier: NCT01920711.
Abstract P6-10-07: Differences in genome-wide DNA methylation levels in breast milk by race and lactation duration
Abstract Introduction: Identifying biomarkers of breast cancer risk among young women would have value in developing effective screening and prevention strategies at early ages. We have proposed that DNA methylation analysis of breast milk may provide breast cancer risk information among young women, and could possibly provide etiologic clues related to the higher rates of early onset cancers among African American as compared with White women in the US. Objective: The purpose of this project was to identify associations between genome-wide DNA methylation levels in breast milk and race adjusted for other breast cancer risk factors. Study Population: Cancer-free, lactating U.S. Black (n=57) and White (n=82) women, ages 19 to 44, provided frozen breast milk samples, as well as demographic, behavioral, and reproductive data, to the Breastmilk Laboratory at University of Massachusetts Amherst. Women were uniparous and did not have a personal history of breast cancer at the time of milk donation. Methods: DNA was extracted from breast milk samples using the phenol-chloroform method. Genome-wide methylation analysis was performed on breast milk samples using the Infinium HumanMethylation450 BeadChip. Probes with 50% or more missing data, cross-reactive probes, as well as probes with minor allelic frequency greater than 0.05 in European- or African-Americans were removed, leaving 379,042 CpG sites for analysis. Multivariate generalized linear regression models were used to examine associations between race and other breast cancer risk factors and methylation beta values, adjusting for potential confounding factors. P-values less than 1E-7 were considered statistically significant. Results: Black women in this study were more likely to be never smokers, to not have used over-the-counter pain medication in the past week, and to breastfeed longer. After adjustment by age, BMI, smoking status, and batch number, race was significantly associated with differential methylation at 1143 CpG sites, including 1024 at which Black women demonstrated increased methylation levels. Additionally, breastfeeding duration was associated with 269 CpG sites, with 268 showing a significant inverse relationship with methylation. Methylation sites significantly associated with Black race and lactation duration were located within tumor suppressor and promoter genes as well as in genes implicated in obesity and diabetes. Conclusion: This preliminarily analysis of DNA methylation in breast milk suggests that Black women have increased methylation and longer breastfeeding is associated with reduced methylation. Further research to understand how etiologic factors related to breast cancer may alter DNA methylation patterns in normal breast may lead to improved understanding of breast cancer risk at a young age and potentially causes of racial disparities in breast cancer incidence between White and Black women. Citation Format: Davis Lynn BC, Bodelon C, Pfeiffer RM, Yang HP, Yang H, Lee M, Laird PW, Campan M, Weisenberger DJ, Murphy J, Sherman ME, Browne EP, Anderton DL, Arcaro KF, Gierach GL. Differences in genome-wide DNA methylation levels in breast milk by race and lactation duration [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P6-10-07.
Fish oil and neurovascular reactivity to mental stress in humans
Omega-3 fatty acids found in fish oil have been suggested to protect against cardiovascular disease, yet underlying mechanisms remain unclear. Despite the well-documented link between mental stress and cardiovascular risk, no study has examined neural cardiovascular reactivity to mental stress after fish oil supplementation. We hypothesized that fish oil would blunt the blood pressure, heart rate (HR), and muscle sympathetic nerve activity (MSNA) responsiveness to mental stress and/or augment limb vasodilation associated with mental stress. Blood pressure, HR, MSNA, forearm vascular conductance (FVC), and calf vascular conductance (CVC) responses were recorded during a 5-min mental stress protocol in 67 nonhypertensive subjects before and after 8 wk of fish oil ( n = 34) or placebo supplementation ( n = 33). Fish oil blunted HR reactivity to mental stress (group × condition × time interactions, P = 0.012) but did not alter blood pressure reactivity to mental stress (interactions, P > 0.05). Fish oil blunted total MSNA reactivity to mental stress (interaction, P = 0.039) but did not alter MSNA burst frequency and burst incidence reactivity (interactions, P > 0.05). Finally, fish oil significantly blunted CVC reactivity to mental stress (interaction, P = 0.013) but did not alter FVC reactivity (interaction, P > 0.05). In conclusion, 8 wk of fish oil supplementation significantly attenuated both HR and total MSNA reactivity to mental stress and elicited a paradoxical blunting of calf vascular conductance. These findings support and extend the growing evidence that fish oil may have positive health benefits regarding neural cardiovascular control in humans.
The antihypertensive influence of fish oil is controversial, and the mechanisms remain unclear. Because the inverse relation between fish oil and hypertension appears to be partially dependent on the degree of hypertension, we tested the hypothesis that fish oil would elicit more dramatic reductions in mean arterial pressure (MAP) and muscle sympathetic nerve activity (MSNA) in prehypertensive (PHT) compared with normotensive (NT) subjects. Resting MAP, MSNA, and heart rate (HR) were examined before and after 8 wk of fish oil (9 g/day; 1.6 g eicosapentaenoic acid and 1.1 g docosahexaenoic acid) or placebo (olive oil; 9 g/day) in 38 NT (19 fish oil; 19 placebo) and 29 PHT (15 fish oil; 14 placebo) volunteers. Fish oil did not alter resting MAP, MSNA, or HR in either NT (80 ± 1 to 80 ± 1 mmHg; 11 ± 2 to 10 ± 1 bursts/min; 71 ± 2 to 71 ± 2 beats/min) or PHT (88 ± 2 to 87 ± 1 mmHg; 11 ± 2 to 10 ± 2 bursts/min; 73 ± 2 to 73 ± 2 beats/min) subjects. When NT and PHT groups were consolidated, analysis of covariance confirmed that pretreatment resting MAP was not associated with changes in MSNA after fish oil. In contrast, pretreatment resting HR was correlated with changes in MSNA ( r = 0.47; P = 0.007) and MAP ( r = 0.42; P < 0.007) after fish oil but not placebo. In conclusion, fish oil did not alter sympathetic neural control in NT or PHT subjects. However, our findings suggest that fish oil is associated with modest sympathoinhibition in individuals with higher resting heart rates, a finding that is consistent with a recent meta-analysis examining the relations among fish oil, HR, and the risk of cardiovascular disease.