A benefit-risk assessment of agents used in the secondary prevention of stroke

Metabolic Interventions to Prevent Hypertrophy-Induced Alterations in Contractile Properties In Vitro

(1) Background: The exact mechanism(s) underlying pathological changes in a heart in transition to hypertrophy and failure are not yet fully understood. However, alterations in cardiac energy metabolism seem to be an important contributor. We characterized an in vitro model of adrenergic stimulation-induced cardiac hypertrophy for studying metabolic, structural, and functional changes over time. Accordingly, we investigated whether metabolic interventions prevent cardiac structural and functional changes; (2) Methods: Primary rat cardiomyocytes were treated with phenylephrine (PE) for 16 h, 24 h, or 48 h, whereafter hypertrophic marker expression, protein synthesis rate, glucose uptake, and contractile function were assessed; (3) Results: 24 h PE treatment increased expression of hypertrophic markers, phosphorylation of hypertrophy-related signaling kinases, protein synthesis, and glucose uptake. Importantly, the increased glucose uptake preceded structural and functional changes, suggesting a causal role for metabolism in the onset of PE-induced hypertrophy. Indeed, PE treatment in the presence of a PAN-Akt inhibitor or of a GLUT4 inhibitor dipyridamole prevented PE-induced increases in cellular glucose uptake and ameliorated PE-induced contractile alterations; (4) Conclusions: Pharmacological interventions, forcing substrate metabolism away from glucose utilization, improved contractile properties in PE-treated cardiomyocytes, suggesting that targeting glucose uptake, independent from protein synthesis, forms a promising strategy to prevent hypertrophy and hypertrophy-induced cardiac dysfunction.

Timing of Aspirin and Secondary Preventative Therapies in Acute Stroke: Support for Use of Stroke Units

Background: We aimed to study the timing of aspirin prescription in ischaemic stroke comparing patients admitted to an acute stroke unit (ASU) directly or via a general medical ward. We also analysed prescription of secondary preventive therapies in stroke patients in an ASU. Methods: Retrospective analysis was made of medical notes and prescription records of 69 patients admitted to an ASU over a three month period to establish timing of aspirin prescription with respect to onset of stroke symptoms, CT brain scan and route of admission to the ASU. Results: CT brain scans were obtained at a median of 2.1 days post stroke (IQ range 1.3–4.3). Patients directly admitted to the ASU received aspirin earlier post admission compared to those admitted via a medical ward (0.7 vs 2.2 days, p<0.01) and were also more likely to receive aspirin prior to CT scan being performed (57% vs 19%, p=0.02). 86% of stroke patients were discharged on an antiplatelet therapy, 79% on a statin, 37% on a thiazide diuretic and 32% on an ACE inhibitor or angiotensin II antagonist. Conclusion: Aspirin was given more promptly in acute stroke and more commonly prior to CT scanning in an ASU compared to a medical ward. Statin therapy is used extensively in stroke but there is a much lower rate of initiation of other secondary preventive therapies (e.g. anti-hypertensive therapy) in hospital. These findings demonstrate a hesitancy in early use of aspirin amongst general physicians and lends support for the use of stroke units.

Evaluación a corto plazo del control de los factores de riesgo y de la prescripción terapéutica en prevención secundaria de enfermedad cardiovascular

INTRODUCTION

Quantify risk factor control and compliance of present therapeutic recommendations in the two months following an acute myocardial infarction (AMI) or ischemic stroke.

MATERIAL AND METHODS

Cross-sectional, descriptive study of risk factors and treatments prescribed on discharge after AMI or stroke.

RESULTS

A total of 68% of 122 patients (65.6% AMI; 22.1% women; mean age: 64.9), had controlled BP; 70.1% BMI < 30 kg/m2; 54.1% LDL-cholesterol < 100 mg/dl. Controlled BP (78.7% versus 50%) and adequate LDL-cholesterol (62.3% versus 20.5%) were greater after AMI than after stroke (p < 0.001). ACEI/ARA II prescribed after AMI: 30% (p < 0.001). After AMI, 26.2% without beta blocker (only 8.8% contraindicated). HbA1c < 7% in 55.5% of diabetics; BP control inferior to non-diabetics (p < 0.001).

DISCUSSION

Short term control of the risk factors after cardiovascular episode and prescription on hospital discharge are improvable, above all after a stroke.

Dipyridamole alters cardiac substrate preference by inducing translocation of FAT/CD36, but not that of GLUT4

In cardiac myocytes, uptake rates of glucose and long-chain fatty acids (FA) are regulated by translocation of GLUT4 and FA translocase (FAT)/CD36, respectively, from intracellular stores to the sarcolemma. Insulin and contractions are two major physiological stimuli able to induce translocation of both transporters and therefore enhance the uptake of both substrates. Interestingly, the cardiovascular drug dipyridamole was able to enhance FA uptake but had no effect on glucose uptake. The selective stimulatory effect of dipyridamole on FA uptake was unrelated to its effects on phosphodiesterase inhibition and on nucleoside transport inhibition. However, dipyridamole-stimulated FA uptake was abolished in the presence of sulfo-N-succinimidylpalmitate, which indicated that FAT/CD36 is involved in the uptake process. Furthermore, the effect was additive to that of insulin but not to that of the AMP-elevating agent oligomycin, indicating that dipyridamole stimulates FAT/CD36-mediated FA uptake by activating the AMP-activated protein kinase (AMPK) signaling pathway. Dipyridamole, however, neither influenced the intracellular AMP content nor induced activation of AMPK. Finally, dipyridamole was able to induce FAT/CD36 translocation from intracellular storage sites to the sarcolemma but had no effect on the subcellular distribution of GLUT4. It is concluded that beyond AMP-activated protein kinase the contraction-induced and AMPK-mediated signal branches off into separate mobilization of GLUT4 and of FAT/CD36, and that dipyridamole activates a yet unidentified target in the FAT/CD36 mobilizing branch.