Remote cardiac ischemic conditioning: Underlying mechanisms and clinical applications

Despite a significant improvement in the care of acute coronary disease, mortality and morbidity remain important. One explanation for this lies in the fact that the very coronary reperfusion may paradoxically result in additional myocardial injury, through the so-called ischemia-reperfusion injury, partially mitigating the beneficial effects of myocardial reperfusion. Over the past two decades, numerous pharmacological interventions (such as the use of antioxidants, anti-inflammatory, magnesium, glucose/insulin/potassium, rapid normalization of pH) were studied in order to prevent ischemia-reperfusion injury. Despite the promising results obtained in animal experiments, attempts to transpose these results to humans, and consequently to clinical practice, have been disappointing. On the other hand, cardiac ischemic conditioning is an intervention that has produced positive results. Ischemic conditioning refers to the protection induced by short periods of ischemia followed by reperfusion, prior to a major ischemic event. Ischemic stimulus can be applied before (pre-conditioning), during (per-conditioning) or after (post-conditioning) the major ischemic event. An important finding regarding cardiac ischemic conditioning, was that protection could be induced remotely, introducing the concept of remote ischemic conditioning. In this paper, we proposed to review the mechanisms underlying remote ischemic cardiac conditioning and the possible clinical applications, considering more specifically pre and per-conditionin

A Critical Analysis of the Available In Vitro

Angiogenesis is a biological process with a central role in retinal diseases. The choice of the ideal method to study angiogenesis, particularly in the retina, remains a problem. Angiogenesis can be assessed through in vitro and in vivo studies. In spite of inherent limitations, in vitro studies are faster, easier to perform and quantify, and typically less expensive and allow the study of isolated angiogenesis steps. We performed a systematic review of PubMed searching for original articles that applied in vitro or ex vivo angiogenic retinal assays until May 2017, presenting the available assays and discussing their applicability, advantages, and disadvantages. Most of the studies evaluated migration, proliferation, and tube formation of endothelial cells in response to inhibitory or stimulatory compounds. Other aspects of angiogenesis were studied by assessing cell permeability, adhesion, or apoptosis, as well as by implementing organotypic models of the retina. Emphasis is placed on how the methods are applied and how they can contribute to retinal angiogenesis comprehension. We also discuss how to choose the best cell culture to implement these methods. When applied together, in vitro and ex vivo studies constitute a powerful tool to improve retinal angiogenesis knowledge. This review provides support for researchers to better select the most suitable protocols in this field

Remote ischemic conditioning in ST-elevation myocardial infarction as adjuvant to primary angioplasty (RIC-STEMI): study protocol for a randomized controlled trial

BACKGROUND: ST-elevation myocardial infarction (STEMI) accounts for nearly one third of acute coronary syndromes. Despite improved STEMI patient care, mortality remains high, contributing significantly to the ischemic heart disease burden. This may partly be related to ischemia-reperfusion injury (IRI). Remote ischemic conditioning (RIC), through short cycles of ischemia-reperfusion applied to a limb, has been shown to reduce IRI in various clinical settings. Our primary hypothesis is that RIC will reduce adverse events related to STEMI when applied as adjunctive therapy to primary percutaneous coronary intervention (PCI). METHODS/DESIGN: "Remote ischemic conditioning in ST-elevation myocardial infarction as adjuvant to primary angioplasty" (RIC-STEMI) is an ongoing prospective, single-center, open-label, randomized controlled trial to assess whether RIC as an adjunctive therapy during primary PCI in patients presenting with STEMI can improve clinical outcomes. After enrollment, participants are randomized according to a computer-generated randomization schedule, in a ratio of 1:1 to RIC or no intervention, in blocks of four individuals. RIC is begun at least 10 min before the estimated time of the first balloon inflation and its duration is 30 min. Ischemia is induced by three cycles of inflation of a blood pressure cuff placed on the left lower limb to 200 mmHg and then deflation to 0 mmHg for another 5 min. Primary endpoint is a combined endpoint of death from cardiac cause or hospitalization for heart failure (HF) on follow-up (including device implantation: implantable cardioverter defibrillator, cardiac resynchronization and left ventricular assist device). Secondary endpoints are myocardial infarction (MI) size (estimated by the 48 h area under the curve of serum troponin I levels), development of Q-wave MI, left ventricular function (assessed by echocardiography within the first 3 days after admission), contrast-induced nephropathy, in-hospital mortality, all-cause mortality and, finally, major adverse cardiovascular events. Patients will have a minimum follow-up period of 12 months. From 11 March 2013 to 31 December 2014, 324 patients have been enrolled and randomized. We expect to complete enrollment of the 494 patients deemed necessary within 3 years.info:eu-repo/semantics/publishedVersio

Moderate exercise training provides left ventricular tolerance to acute pressure overload

Moreira-Goncalves D, Henriques-Coelho T, Fonseca H, Ferreira RM, Amado F, Leite-Moreira A, Duarte JA. Moderate exercise training provides left ventricular tolerance to acute pressure overload. Am J Physiol Heart Circ Physiol 300: H1044-H1052, 2011. First published December 24, 2010; doi: 10.1152/ajpheart.01008.2010.-The present study evaluated the impact of moderate exercise training on the cardiac tolerance to acute pressure overload. Male Wistar rats were randomly submitted to exercise training or sedentary lifestyle for 14 wk. At the end of this period, the animals were anaesthetized, mechanically ventilated, and submitted to hemodynamic evaluation with biventricular tip pressure manometers. Acute pressure overload was induced by banding the descending aorta to induce a 60% increase of peak systolic left ventricular pressure during 120 min. This resulted in the following experimental groups: 1) sedentary without banding (SED + Sham), 2) sedentary with banding (SED + Band), and 3) exercise trained with banding (EX + Band). In response to aortic banding, SED + Band animals could not sustain the 60% increase of peak systolic pressure for 120 min, even with additional narrowing of the banding. This was accompanied by a reduction of dP/dt(max) and dP/dt(min) and a prolongation of the time constant tau, indicating impaired systolic and diastolic function. This impairment was not observed in EX + Band (P < 0.05 vs. SED + Band). Additionally, compared with SED + Band, EX + Band presented less myocardial damage, exhibited attenuated protein expression of active caspase-3 and NF-kappa B (P < 0.016), and showed less protein carbonylation and nitration (P < 0.05). These findings support our hypothesis that exercise training has a protective role in the modulation of the early cardiac response to pressure overload

Physical properties of single-crystalline fibers of the colossal-magnetoresistance manganite La0.7Ca0.3MnO3

We have grown high-quality single crystals of the colossal-magnetoresistance (CMR) material La0.7Ca0.3MnO3 by using the laser heated pedestal growth (LHPG) method. Samples were grown as fibers of different diameters, and with lengths of the order of centimeters. Their composition and structure were verified through X-ray diffraction, scanning electron microcopy with EDX (Energy Dispersive X-ray Analysis) and by Rietveld analysis. The quality of the crystalline fibers was confirmed by Laue and EBSD (Electron Backscatter Diffraction) patterns. Rocking curves performed along the fiber axis revealed a half-height width of 0.073 degrees. The CMR behavior was confirmed by electrical resistivity and magnetization measurements as a function of temperature.Comment: 11 pages (including 3 figures); to appear in Appl. Phys. Let

Thyroid Hormones within the Normal Range and Cardiac Function in the General Population: The EPIPorto Study

Background: Hypothyroidism and hyperthyroidism are associated with marked changes in cardiac structure and function. However, the association of thyroid function within the normal range with cardiac structure and function in the general population remains uncertain. Methods: Eight hundred thirty-five subjects aged ≥45 years from the EPIPorto cohort (evaluation between 2006 and 2008) were cross-sectionally analyzed. We excluded participants with TSH, free T4 (FT4), or free T3 (FT3) outside of the reference range or with self-reported cardiovascular or thyroid disease. Cardiac structure and function were evaluated by echocardiography. We used linear regression models unadjusted and adjusted for sex and age (model 1), and sex, age, BMI, diabetes, hypertension, and smoking (model 2). Nonlinear associations were assessed using restricted cubic splines. Results: The mean age was 61.5 years (SD 10.5); 61.1% of the patients were women. In the adjusted model 2, heart rate was positively associated with FT3; diastolic blood pressure was positively associated with TSH; LV end-diastolic and end-systolic volumes were inversely associated with TSH, and ejection fraction was nonlinearly associated with FT3, with higher ejection fractions near the limits of the reference range. Left ventricle (LV) posterior wall thickness was nonlinearly associated with FT4 in the adjusted model 1, with a greater thickness near the limits of the reference range. Regarding diastolic function, no significant associations were observed in adjusted models. Conclusions: Thyroid function within the reference range was associated with heart rate, blood pressure, cardiac structure, and function. Increasing thyroid function (lower TSH, higher FT4, or higher FT3) was associated with a higher heart rate, a lower diastolic blood pressure, and larger LV volumes. LV wall thickness and ejection fraction had a U-shaped association with thyroid hormones.This work was supported by the DOCnet project (NORTE-01-0145-FEDER-000003), supported by Norte Portugal Regional Operational Program (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), and the NETDIAMOND project (POCI-01-0145-FEDER-016385), supported by European Structural and Investment Funds, Lisbon’s Regional Operational Program 2020, and national funds from the Portuguese Foundation for Science and Technology – both projects through the Cardiovascular Research Center (UnIC, FCT 51/94) – and by the Portuguese Foundation for Science and Technology (grant POCI/SAU-ESP/61492/2004) and the Unidade de Investigação em Epidemiologia – Instituto de Saúde Pública da Universidade do Porto (EPIUnit) (POCI-01-0145-FEDER-006862, ref. info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UID/DTP/04750/2013/PT)