Biomedical subjects

Pedro Monteiro

Publications and source records attributed to Pedro Monteiro.

24 records · Page 2Linked to original sources

PubMed2003

Pharmacological modulation of mitochondrial function during ischemia and reperfusion.

In recent years, basic research has enabled a better understanding of the molecular and cellular basis of myocardial ischemia. In this context, cardiac mitochondria have been shown to perform an important role, being essential to energy production and ionic homeostasis, and thus controlling cardioprotection and cell death. Knowledge of these facts has led to the development of new therapeutic strategies for myocardial ischemia, aiming to modify its biochemical pathways and to preserve mitochondrial function. It has also led to a better understanding of the cellular and subcellular effects of classical anti-ischemic drugs, revealing that most of them also have a direct impact on cardiac mitochondrial function. This article summarizes what is currently known regarding the pharmacological modulation of mitochondrial function during ischemia and reperfusion and how it can induce cardioprotection in coronary artery disease patients.

Animals↗

PubMed2003

Long-term clinical impact of coronary-collateral vessels after acute myocardial infarction.

BACKGROUND: The positive impact of coronary collateral vessels in the acute phase of myocardial infarction (AMI) is already well established. However, their impact on longterm clinical outcome of these patients is still unclear. AIM: To study the impact of the presence of well established coronary collateral vessels on long-term clinical outcome of post-AMI patients. POPULATION AND METHODS: We analyzed the clinical evolution (mean follow-up time of 15.66.8 months) of 70 patients who underwent coronary angiography shortly after AMI. According to the angiogram, the patients were divided into 2 groups: those with well developed coronary collateral vessels (n = 35) and those who did not show developed collateral circulation (n = 35). RESULTS: Both groups had similar baseline characteristics (regarding demography, coronary artery disease risk factors and predischarge evolution). The group with collaterals had more severe coronary disease compared with the group without collaterals (2.31 +/- 0.61 vs. 1.57 +/- 0.7; p = 0.00001). Moreover, this group more frequently showed significant lesions on the left anterior descending artery (83% vs. 74%; p = NS), left circumflex (71% vs. 43%; p = 0.02) and right coronary arteries (74% vs. 40%; p = 0.003). Primary percutaneous coronary intervention was more often performed in patients without coronary collateral vessels (58% vs. 30%; p = 0.02). Left ventricular function was similar in both groups. During follow-up, both groups underwent similar levels of revascularization by percutaneous coronary intervention and/or coronary artery bypass graft (70% vs. 76%; p = NS). Despite these characteristics, the group with collaterals showed a significantly better clinical outcome, with fewer events (combined endpoint of unstable angina, non-fatal AMI, heart failure and death) after hospital discharge (40% vs. 69%; p = 0.02) and a lower CCS functional class at the end of follow-up (1.26 +/- 0.63 vs. 1.730.71; p = 0.03). CONCLUSION: After acute myocardial infarction, the presence of collateral vessels is associated with a better long-term clinical outcome.

Aged↗

PubMed2002

Impact of diabetes on induction of the mitochondrial permeability transition.

Diabetes is one of the most common metabolic diseases of our times. Specific cardiovascular alterations are often associated with the progression of this disease. Considerable controversy exists in the literature concerning the greater or lesser susceptibility of the diabetic heart to ischemia and reperfusion. Cardiac mitochondria may be fundamental to the differential susceptibility of the cardiomyocyte to pathologic phenomena, particularly those due to the induction of the degenerative process known as the mitochondrial permeability transition (MPT), which is triggered by excessive mitochondrial calcium accumulation. The MPT has been associated with cellular dysfunction resulting from ischemia and reperfusion. The objective of this work was to examine the susceptibility of mitochondria isolated from diabetic rats to the MPT, in comparison to healthy control rats of the same age. Cardiac mitochondria from the diabetic rats had higher calcium loading capacity before the development of the MPT, with a decreased incidence of MPTP-associated features. This was associated with a greater capacity to sustain multiple pulses of externally added calcium, simultaneously with maintenance of the transmembrane electrical potential and reduced swelling amplitude. This could mean that cardiomyocytes from diabetic hearts may indeed be less prone to dysfunctions resulting from ischemia and reperfusion, at least in milder diabetic conditions, thus explaining many reports in the literature.

Animals↗

PubMed2002

Impact of carvedilol on the mitochondrial damage induced by hypoxanthine and xantine oxidase--what role in myocardial ischemia and reperfusion?

OBJECTIVES: The cardioprotective effects of carvedilol (CV) may be explained in part by interactions with heart mitochondria. The objective of this work was to study the protection afforded by CV against oxidative stress induced in isolated heart mitochondria by hypoxanthine and xanthine oxidase (HX/XO), a well-known source of reactive oxygen species (ROS) in the cardiovascular system. METHODS: Mitochondria were isolated from Wistar rat hearts (n = 8) and incubated with HX/XO in the presence and in the absence of calcium. Several methods were used to assess the protection afforded by CV: evaluation of mitochondrial volume changes (by measuring changes in the optical density of the mitochondrial suspension), calcium uptake and release (with a fluorescent probe, Calcium Green 5-N) and mitochondrial respiration (with a Clark-type oxygen electrode). RESULTS: CV decreased mitochondrial damage associated with ROS production by HX and XO, as verified by the reduction of mitochondrial swelling and increase in mitochondrial calcium uptake. In the presence of HX and XO, CV also ameliorated mitochondrial respiration in the active phosphorylation state and prevented decrease in the respiratory control ratio (p < 0.05) and in mitochondrial phosphorylative efficiency (p < 0.001). CONCLUSIONS: The data indicate that CV partly protected heart mitochondria from oxidative damage induced by HX and XO, which may be useful during myocardial ischemia and reperfusion. It is also suggested that mitochondria may be a priority target for the protective action of some compounds.

Animals↗

PubMedDate not supplied

Pilot study to show the loss of important data in nursing handover.

A good nursing handover process is a crucial part of providing quality nursing care in a modern healthcare environment. The conservation of patient data during the handover process is vital to ensure good continuity of care and safe practice. Any errors or omissions made during the handover process may have dangerous consequences. The authors observed the handover of 12 simulated patients over five consecutive handover cycles between nurses. Three handover styles were used and the amount of data loss was recorded for each style. A purely verbal handover style resulted in the loss of all data after three cycles. A note-taking style (the traditional style used in most hospital wards) resulted in only 31% of data being transferred correctly after five cycles. When a typed sheet was included with the verbal handover, data loss was minimal. Current handover methods may result in significant loss of important data that may impact on patient care. The authors recommend that prior to handover, a formal handover sheet be constructed that can be transferred as part of the handover process.

Communication↗

PubMedDate not supplied

The worse hospital outcome of diabetic patients is not explained by the severity of underlying coronary artery disease.

INTRODUCTION: Diabetes mellitus has a high prevalence in developed countries and is associated with high cardiovascular morbidity and mortality rates. In this study we evaluated in-hospital evolution of diabetic patients admitted to a cardiac care unit with acute coronary syndrome without ST segment elevation. METHODS: We analyzed a population of 176 consecutive patients, 36 (21%) with diabetes, admitted with chest pain at rest, elevated biological markers for myocardial necrosis and/or ST segment/T wave changes suggestive of myocardial ischemia. RESULTS: The groups were similar in terms of age, sex, presence of other risk factors for coronary artery disease (CAD), past history of CAD or myocardial revascularization. There were no differences between the groups with respect to extent of CAD, left ventricular function or blood levels of biological markers. The comparison between the two groups did not show any statistical difference concerning the following in-hospital events: non-Q wave MI, Q-wave MI, PTCA and death. On the other hand, the diabetic patients had a worse outcome in term of congestive heart failure (25% and 11%, p = 0.04), CABG (25% and 10%, p = 0.02) and combination of death, congestive heart failure and Q-wave MI (42% and 23%, p = 0.02). CONCLUSION: In spite of similar extent of CAD and similar left ventricular function, diabetes mellitus in patients with acute coronary syndrome without ST segment elevation identifies a higher-risk population with more complicated in-hospital outcome.

Acute Disease↗