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Bmal1 in Perivascular Adipose Tissue Regulates Resting-Phase Blood Pressure Through Transcriptional Regulation of Angiotensinogen [Original Research Article]

Circulation - Lun, 02/07/2018 - 19:45
Background:The perivascular adipose tissue (PVAT) surrounding vessels constitutes a distinct functional integral layer of the vasculature required to preserve vascular tone under physiological conditions. However, there is little information on the relationship between PVAT and blood pressure regulation, including its potential contributions to circadian blood pressure variation.Methods:Using unique brown adipocyte–specific aryl hydrocarbon receptor nuclear translocator-like protein 1 (Bmal1) and angiotensinogen knockout mice, we determined the vasoactivity of homogenized PVAT in aortic rings and how brown adipocyte peripheral expression of Bmal1 and angiotensinogen in PVAT regulates the amplitude of diurnal change in blood pressure in mice.Results:We uncovered a peripheral clock in PVAT and demonstrated that loss of Bmal1 in PVAT reduces blood pressure in mice during the resting phase, leading to a superdipper phenotype. PVAT extracts from wild-type mice significantly induced contractility of isolated aortic rings in vitro in an endothelium-independent manner. This property was impaired in PVAT from brown adipocyte–selective Bmal1-deficient (BA-Bmal1-KO) mice. The PVAT contractile properties were mediated by local angiotensin II, operating through angiotensin II type 1 receptor–dependent signaling in the isolated vessels and linked to PVAT circadian regulation of angiotensinogen. Indeed, angiotensinogen mRNA and angiotensin II levels in PVAT of BA-Bmal1-KO mice were significantly reduced. Systemic infusion of angiotensin II, in turn, reduced Bmal1 expression in PVAT while eliminating the hypotensive phenotype during the resting phase in BA-Bmal1-KO mice. Angiotensinogen, highly expressed in PVAT, shows circadian expression in PVAT, and selective deletion of angiotensinogen in brown adipocytes recapitulates the phenotype of selective deletion of Bmal1 in brown adipocytes. Furthermore, angiotensinogen is a transcriptional target of Bmal1 in PVAT.Conclusions:These data indicate that local Bmal1 in PVAT regulates angiotensinogen expression and the ensuing increase in angiotensin II, which acts on smooth muscle cells in the vessel walls to regulate vasoactivity and blood pressure in a circadian fashion during the resting phase. These findings will contribute to a better understanding of the cardiovascular complications of circadian disorders, alterations in the circadian dipping phenotype, and cross-talk between systemic and peripheral regulation of blood pressure.

Anemia and Iron Deficiency in Heart Failure [In Depth]

Circulation - Lun, 02/07/2018 - 19:45
Anemia and iron deficiency are important and common comorbidities that often coexist in patients with heart failure. Both conditions, together or independently, are associated with poor clinical status and worse outcomes. Whether anemia and iron deficiency are just markers of heart failure severity or whether they mediate heart failure progression and outcomes and therefore should be treated is not entirely clear. Treatment of anemia in patients with heart failure with erythropoiesis-stimulating agents has been evaluated intensively during the past several years. Unfortunately, these agents did not improve outcomes but were associated with a higher risk of adverse events. Iron deficiency in patients with heart failure can be absolute, when total body iron is decreased, or functional, when total body iron is normal or increased but is inadequate to meet the needs of target tissues because of sequestration in the storage pool. Whereas iron replacement is appropriate in patients with anemia resulting from absolute iron deficiency, it has been unclear whether and how absolute or functional iron deficiency should be treated in nonanemic patients with heart failure. Recently, small studies found that administration of intravenous iron in patients with heart failure and absolute or functional iron deficiency with or without anemia improves symptoms and exercise capacity, but long-term outcomes and safety data are not yet available. In this review, we discuss the causes and pathogenesis of and treatment options for anemia and iron deficiency in patients with heart failure.

[Editorial] Orban not delivering health for Hungary

The Lancet - Sáb, 21/04/2018 - 00:00
Viktor Orban's re-election to a third consecutive term in Hungary offers a preview for western countries of what the health consequences could be for governments that value populism and economic strength over the health of their people. The controversial populist was swept back into power by a wave of support, with a manifesto that included a crackdown on liberal non-governmental organisations. Orban said before the election that his opponents will face “moral, political, and legal revenge”, in the aftermath.

[Editorial] Sexual harassment and abuse—the sinister underbelly

The Lancet - Sáb, 21/04/2018 - 00:00
This week, The Lancet, publishes a Special Report on allegations of sexual harassment and abuse at UNAIDS. The report suggests that UNAIDS has at best marginalised and at worst buried allegations of sexual harassment. Its responses have been unduly weak and unacceptable, and the announcements of remediation are too little too late. Furthermore, internal loyalty to the existing leadership seems to trump integrity in the organisation, and has contributed to a culture devoid of transparency and accountability.

[Editorial] UK COPD treatment: failing to progress

The Lancet - Sáb, 21/04/2018 - 00:00
Chronic obstructive pulmonary disease (COPD) is a major cause of mortality in the world today. More than a million British people lived with diagnosed COPD in the UK in 2014–15, or just under 2% of the population. COPD admissions to emergency services in the UK are on the rise, but, access to treatments shown to reduce patients' time spent in hospital is still woefully inadequate.

[Comment] Social lobbying: a call to arms for public health

The Lancet - Sáb, 21/04/2018 - 00:00
The term lobbying derives from the public lobbies of the UK Houses of Parliament in London, where concerned citizens have gathered since at least the 16th century to speak with elected officials on the sidelines of legislative debates. In today's parlance, lobbying has evolved to represent a more pernicious and systematic approach to influencing lawmakers, occurring much deeper within the corridors of power.
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