Nicolás Valls

Essential hypertension and oxidative stress: New insights.

Essential hypertension is a highly prevalent pathological condition that is considered as one of the most relevant cardiovascular risk factors and is an important cause of morbidity and mortality around the world. Despite the fact that mechanisms underlying hypertension are not yet fully elucidated, a large amount of evidence shows that oxidative stress plays a central role in its pathophysiology. Oxidative stress can be defined as an imbalance between oxidant agents, such as superoxide anion, and antioxidant molecules, and leads to a decrease in nitric oxide bioavailability, which is the main factor responsible for maintaining the vascular tone. Several vasoconstrictor peptides, such as angiotensin II, endothelin-1 and urotensin II, act through their receptors to stimulate the production of reactive oxygen species, by activating enzymes like NADPH oxidase and xanthine oxidase. The knowledge of the mechanism described above has allowed generating new therapeutic strategies against hypertension based on the use of antioxidants agents, including vitamin C and E, N-Acetylcysteine, polyphenols and selenium, among others. These substances have different therapeutic targets, but all represent antioxidant reinforcement. Several clinical trials using antioxidants have been made. The aim of the present review is to provide new insights about the key role of oxidative stress in the pathophysiology of essential hypertension and new clinical attempts to demonstrate the usefulness of antioxidant therapy in the treatment of hypertension.

Oxidative Stress in Hypertension: Mechanisms and Therapeutic Opportunities

Hypertension is a highly prevalent disease worldwide. It is known for being one of the most important risk factors for developing cardiovascular disease, including acute myocardial infarction and stroke. Therefore, during the last decades there have been multiple efforts to fully understand the mechanisms underlying hypertension, and then develop effective therapeutic interventions to attenuate the morbidity and mortality associated with this condition. In this regard, oxidative stress has been proposed as a key mechanistic mediator of hypertension, which is an imbalance between oxidant species and the antioxidant defense systems. A large amount of evidence supports the role of vascular wall as a major source of reactive oxygen species. These include the activation of enzymes, such as NADPH oxidase and xanthine oxidase, the uncoupling eNOS and mitochondrial dysfunction, having as a major product the superoxide anion. Among the stimuli that increase the production of oxidative species can be found the action of some vasoactive peptides, such as angiotensin II, endothelin-1 and urotensin II. The oxidative stress state generated leads to a decrease in the biodisponibility of nitric oxide and prostacyclin, key factors in maintaining the vascular tone. The knowledge of the mechanisms mentioned above has allowed generating some therapeutic strategies using antioxidants as antihypertensives with different results. Further studies are required to position antioxidants as key agents in the treatment of hypertension. The current review summarize evidence of the role of oxidative stress in hypertension, emphasizing in therapeutic targets that can be consider in antioxidant therapy.

Potential Role of Polyphenols in the Prevention of Cardiovascular Diseases: Molecular Bases

Cardiovascular diseases (CVD) are the leading cause of mortality worldwide. It is widely accepted that oxidative stress plays a key role in their development and progression; hence oxidative damage might be abrogated by antioxidants. Polyphenols are phytochemicals showing extensively studied antioxidant properties in-vivo. Most representative sources of these compounds include fruits, greens, nuts, herbs, cocoa, tea and coffee. Epidemiological evidence suggests an association between the consumption of polyphenol-rich vegetables and the reduction of cardiovascular disease prevalence. This fact could be related to the anti-inflammatory, antithrombotic and vasodilatory effects of polyphenols. Even though these biological effects could be mainly attributed to the antioxidant activity of polyphenols, other pharmacological mechanisms should also be considered. The latter could comprise direct anti-inflammatory effects, modulation of intracellular signaling and gene expression, improvement of nitric oxide homeostasis, as well as platelet antiaggregation. However, it is noticeable that protocols of interventions to evaluate the properties of polyphenols have failed to show the same positive results reported from observational studies. At present, a controversy exists regarding the actual effectiveness of polyphenols in preventing cardiovascular diseases. Therefore, an improvement of the available knowledge about polyphenol pharmacokinetics, together with a better understanding of the mechanisms of action of these compounds, could be of great benefit. Thus, a rational support for the development of interventional designs could provide reliable evidence on the actual role of polyphenols in CVD prevention.

Amelioration of persistent left ventricular function impairment through increased plasma ascorbate levels following myocardial infarction

Purpose: Percutaneous coronary angioplasty (PCA) has been demonstrated to reduce mortality and morbidity and thereby improve the prognosis of patients undergoing acute myocardial infarctions (AMIs). However, this procedure paradoxically increases the initial damage as the result of a condition known as ‘myocardial reperfusion injury’. Oxidative stress may contribute to the mechanism of this injury. The goal of the present study was to ascertain whether high plasma ascorbate levels could ameliorate the reperfusion injuries that occur after the successful restoration of blood flow. Methods: Patients from three clinical centers of the public health system were included in the study. The groups were formed by either-sex patients with a diagnosis of ST-segment elevation myocardial infarction with an indication for primary PCA. Only the patients who presented with their first myocardial infarction were enrolled. Ascorbate was administered through an infusion given prior to the restoration of the coronary flow, which was then followed by oral treatment with vitamin C (500 mg/12 hours) plus vitamin E (400 IU/day) for 84 days. The left ventricular ejection fraction (LVEF) was determined by using cardiac magnetic resonance on days 6 and 84 following the onset of the reperfusion. In addition, the microvascular function was assessed by an angiographic evaluation using the Thrombolysis In Myocardial Infarction (TIMI) myocardial perfusion grade (TMPG). The results were grouped according to the plasma ascorbate concentration achieved immediately following the onset of reperfusion into either the HA group (high ascorbate, >1 mmol/l) or the LA group (low ascorbate, <1 mmol/l). The biochemical parameters were analyzed throughout the protocol. Results: The LVEF of the HA group was significantly higher than that of the LA group, values on day 84 in the HA group were 33% higher than those of the LA group. The amelioration of the LVEF was accompanied by an improvement in the microvascular dysfunction, after PCA, 95% of the patients in the HA group achieved a TMPG of 2–3, in the LA group only 79% of patients showed a TMPG of 2–3. Conclusions: These data are consistent with the protective effect of high plasma levels of ascorbate against the oxidative challenge caused by reperfusion injury in patients subjected to PCA following an AMI. Further studies are needed to elucidate the mechanism accounting for this beneficial antioxidant effect.

Effects of a novel ascorbate-based protocol on infarct size and ventricle function in acute myocardial infarction patients undergoing percutaneous coronary angioplasty

Introduction This study was designed to test the hypothesis that high-dose ascorbate prior to reperfusion followed by low chronic oral doses ameliorate myocardial reperfusion injury (MRI) in acute myocardial infarction patients subjected to primary percutaneous coronary angioplasty (PCA). Material and methods A randomized double-blind placebo-controlled and multicenter clinical trial was performed on acute myocardial infarction (AMI) patients who underwent PCA. Sodium ascorbate (320 mmol/l, n = 53) or placebo (n = 46) was infused 30 min prior to PCA. Blood samples were drawn at enrolment (M1), after balloon deflation (M2), 6–8 h after M2 (M3) and at discharge (M4). Total antioxidant capacity of plasma (ferric reducing ability of plasma – FRAP), erythrocyte reduced glutathione (GSH) and plasma ascorbate levels were determined in blood samples. Cardiac magnetic resonance (CMR) was performed at 7–15 days and 2–3 months following PCA. Ninety-nine patients were enrolled. In 67 patients, the first CMR was performed, and 40 patients completed follow-up. Results The ascorbate group showed significantly higher ascorbate and FRAP levels and a decrease in the GSH levels at M2 and M3 (p < 0.05). There were no significant differences in the infarct size, indexed end-systolic volume and ejection fraction at both CMRs. There was a significant amelioration in the decreased ejection fraction between the first and second CMR in the ascorbate group (p < 0.05). Conclusions Ascorbate given prior to reperfusion did not show a significant difference in infarct size or ejection fraction. However, it improved the change in ejection fraction determined between 7–15 days and 2–3 months. This result hints at a possible functional effect of ascorbate to ameliorate MRI.

Viable Pregnancy in a patient with metastatic melanoma treated with double checkpoint immunotherapy

Metastatic cancers during pregnancy have historically been associated with dismal outcomes, with greater rates of tumor progression in part because of diminished treatment alternatives. Immunotherapy with T-cell checkpoint inhibitors has significantly impacted the survival of several metastatic tumors. However, given their mechanism of action, immune-related adverse events can occur, especially with combined immunotherapy treatments. During pregnancy, checkpoint pathways have a major role, providing immune tolerance to the fetal allograft. Furthermore, evidence suggests that inhibition of this pathway may be associated with an increased risk of miscarriage. We describe, to our knowledge, the first case reported in the literature of a patient 7 weeks pregnant, diagnosed with metastatic melanoma and treated with nivolumab plus ipilimumab. We also present the associated immune-related side effects and their treatment, as well as the oncologic results that lead to favorable pregnancy outcome.

TCT-696 Oxidative Stress Response in Patients with Severe Aortic Stenosis Undergoing Transcatheter And Surgical Aortic Valve Replacement.

BACKGROUND This study sought to assess the impact of carotid artery stenosis (CAS) on outcomes of patients undergoing transcatheter aortic valve replacement (TAVR). CAS has been associated with the risk of stroke in patients undergoing cardiac surgery. However, little is known about the clinical significance of CAS in the setting of TAVR. METHODS Consecutive patients (n1⁄4312) with severe symptomatic aortic stenosis who underwent a carotid Doppler study immediately prior to TAVR were followed prospectively. Major adverse cardiovascular event (MACE) rates were stratified by the presence of CAS, defined in accodance with current guidelines.

Respecto al artículo: Ácidos grasos Omega 3 en la Nutrición ¿Cómo aportarlos?

(2014) titulado: “Acidos grasos omega-3 en la nutricion ?Como aportar-los? de los autores Alfonso Valenzuela y Rodrigo Valenzuela. Felicitamos a los autores por exponer en nuestro medio un topico relevante, permitiendo la discusion academica debido al impacto para la salud, tanto individual como poblacional, que presentan estos nutrientes.Al respecto, quisieramos discutir algunos de los aspectos presentados en el articulo. Primero, con respecto a lo que se senala: “niveles plasmaticos altos de DHA, que obviamente derivan de un alto consumo de este acido graso, pueden facilitar el desarrollo de cancer prostatico agresivo”, se hace referencia a dos meta-analisis de un mismo grupo de investigacion, los que de acuerdo a los resultados presentados por el equipo de investigacion en sus articulos, no permitirian llegar a conclusion