Plasma parathyroid hormone and risk of congestive heart failure in the community
ABSTRACT In experimental studies parathyroid hormone (PTH) has been associated with underlying causes of heart failure (HF) such as atherosclerosis, left ventricular hypertrophy, and myocardial fibrosis. Individuals with increased levels of PTH, such as primary or secondary hyperparathyroidism patients, have increased risk of ischaemic heart disease and HF. Moreover, increasing PTH is associated with worse prognosis in patients with overt HF. However, the association between PTH and the development HF in the community has not been reported.
In a prospective, community-based study of 864 elderly men without HF or valvular disease at baseline (mean age 71 years, the ULSAM study) the association between plasma (P)-PTH and HF hospitalization was investigated adjusted for established HF risk factors (myocardial infarction, hypertension, diabetes, electrocardiographic left ventricular hypertrophy, smoking, and hypercholesterolaemia) and variables reflecting mineral metabolism (S-calcium, S-phosphate, P-vitamin D, S-albumin, dietary calcium and vitamin D intake, physical activity, glomerular filtration rate, and blood draw season). During follow-up (median 8 years), 75 individuals were hospitalized due to HF. In multivariable Cox-regression analyses, higher P-PTH was associated with increased HF hospitalization (hazard ratio for 1-SD increase of PTH, 1.41, 95% CI 1.12-1.77, P = 0.003). Parathyroid hormone also predicted hospitalization in participants without apparent ischaemic HF and in participants with normal P-PTH.
In a large community-based sample of elderly men, PTH predicted HF hospitalizations, also after accounting for established risk factors and mineral metabolism variables. Our data suggest a role for PTH in the development of HF even in the absence of overt hyperparathyroidism.
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ABSTRACT: Neurohormonal activation involving the hypothalamic-pituitary-adrenal axis and adrenergic nervous and renin-angiotensin-aldosterone systems is integral to stressor state-mediated homeostatic responses. The levels of effector hormones, depending upon the degree of stress, orchestrate the concordant appearance of hypokalemia, ionized hypocalcemia and hypomagnesemia, hypozincemia, and hyposelenemia. Seemingly contradictory to homeostatic responses wherein the constancy of extracellular fluid would be preserved, upregulation of cognate-binding proteins promotes coordinated translocation of cations to injured tissues, where they participate in wound healing. Associated catecholamine-mediated intracellular cation shifts regulate the equilibrium between pro-oxidants and antioxidant defenses, a critical determinant of cell survival. These acute and chronic stressor-induced iterations in extracellular and intracellular cations are collectively referred to as the cation crossroads. Intracellular cation shifts, particularly excessive accumulation of Ca2+, converge on mitochondria to induce oxidative stress and raise the opening potential of their inner membrane permeability transition pores (mPTPs). The ensuing loss of cationic homeostasis and adenosine triphosphate (ATP) production, together with osmotic swelling, leads to organellar degeneration and cellular necrosis. The overall impact of iterations in extracellular and intracellular cations and their influence on cardiac redox state, cardiomyocyte survival, and myocardial structure and function are addressed herein.Journal of the American College of Nutrition 12/2010; 29(6):563-74. DOI:10.1080/07315724.2010.10719895
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ABSTRACT: Congestive heart failure (CHF), a common clinical syndrome, has reached epidemic proportions. Its disabling symptoms account for frequent hospitalizations and readmissions. Pathophysiological mechanisms that lead to CHF and account for its progressive nature are of considerable interest. Important scientific observations obtained from Dr Pawan K Singal's laboratory in Winnipeg, Manitoba, have provided crucial insights to our understanding of the pathophysiological factors that contribute to cardiomyocyte necrosis (the heart is a postmitotic organ incapable of tolerating an ongoing loss of these cells without adverse functional consequences). This increment in knowledge and the mechanistic insights afforded by Dr Singal and his colleagues have highlighted the role of excessive intracellular calcium accumulation and the appearance of oxidative stress in CHF, in which the rate of reactive oxygen species generation overwhelms their rate of detoxification by antioxidant defenses. They have shown that this common pathophysiological scenario applies to diverse entities such as ischemia/reperfusion and hypoxia/reoxygenation forms of injury, myocardial infarction and the cardiomyopathies that accompany diabetes and excess levels of catecholamines and adriamycin. The authors are honoured to be invited to contribute to the present focus issue of Experimental & Clinical Cardiology in recognizing Dr Singal's numerous scholarly accomplishments. The present article reviews the authors' recent work on a mitochondriocentric signal-transducer-effector pathway to cardiomyocyte necrosis found in rats with either an acute stressor state that accompanies isoproterenol administration or a chronic stressor state manifested after four weeks of aldosterone/salt treatment.Experimental and clinical cardiology 01/2011; 16(4):109-15.
Article: Vitamin D in chronic heart failure.[Show abstract] [Hide abstract]
ABSTRACT: Recent evidence suggests a number of mechanisms whereby vitamin D may positively influence the pathophysiology of heart failure. These include actions on the renin-angiotensin system, calcium handling, reduction of proinflammatory cytokines, and improvements in endothelial function and blood pressure. Observational data suggest that low vitamin D levels are common in patients with heart failure and are associated with worse exercise capacity and natriuretic peptide levels. Little interventional data are currently available, but evidence to date does not support vitamin D supplementation, even in patients with low vitamin D levels. Further studies are needed to establish whether larger doses of vitamin D given over a longer period of time can reduce symptoms, hospitalization, and mortality in heart failure.Current Heart Failure Reports 02/2011; 8(2):123-30. DOI:10.1007/s11897-011-0048-6