Endothelial function and endothelial progenitors: possible mediators of the benefits from physical exercise?

Assessing the knowledge of medical undergraduates on oral anticoagulation therapy

Objective

Oral anticoagulant drugs, such as warfarin, are widely used for preventing and treating vascular and thromboembolic disease in patients with chronic atrial fibrillation, venous thrombosis, and coronary heart disease. As oral anticoagulant therapy has such a narrow therapeutic range, complications in administering these drugs can prove to have a detrimental effect on patients such as life-threatening bleeding might occur. It is therefore necessary to have an adequate knowledge about its actions and its interactions with other dietary factors or any other medication involved. This study was therefore formulated in order to evaluate the knowledge as well as to impart proper awareness to the medical undergraduate students about oral anticoagulation therapy such as to prevent any untoward situation that may arise from the process.

Methods

A cross-sectional descriptive study was used to assess the knowledge on oral anticoagulant therapy among the medical undergraduates of a tertiary care hospital. A pre-validated structured questionnaire consisting of 28 questions was adopted, and a separate questionnaire was used for each student. Timing of answering the questionnaire was set at 30 minutes. Scores were evaluated such as a correct answer was given a score of one and wrong answer awarded as zero. Adequate knowledge sore was set above 70% and inadequate knowledge at less than 40%.

Results

The response rate was found out to be 67.33% with gender distribution observed to be 71% females and 29% males. From the answers evaluated, overall average score of 67.3 ± 15.9 was obtained indicating that most of the respondents have adequate knowledge about the different mechanism, drug-drug interactions, drug-food interactions, and side effects of anticoagulant therapy, and 100% of the students are well aware about the complications and procedures involved to dissipate information about warfarin therapy.

Conclusions

Adequate exposure of students to clinical cases will further help them to focus on the importance of anticoagulation and strengthening their knowledge regarding anticoagulant drug therapy. This will influence the process of physician-patient communication for improving anticoagulation outcome.

Influence of regular physical activity on warfarin dose and risk of hemorrhagic complications

OBJECTIVE

To determine the influence of regular physical activity on stable warfarin dose and risk of major hemorrhage in patients on chronic anticoagulation therapy.

DESIGN

Regular physical activity (maintained over > 80% of visits) was ascertained by self-report at initiation of warfarin therapy (target international normalized ratio [INR] = 2-3) in 1272 patients, with changes documented at monthly anticoagulation clinic visits in a population-based prospective cohort. Multi-variable linear regression and survival analysis, respectively, were used to assess influence on warfarin and risk of hemorrhage.

SETTING

Outpatient anticoagulation clinic

PARTICIPANTS

1272 anticoagulated patients

MEASUREMENT AND MAIN RESULTS

There were 683 (53.7%) patients who were regularly physically active (≥ 30 min ≥ 3 times/week). Physically active patients required warfarin doses that were 6.9% higher (p=0.006) than in physically inactive patients after controlling for sociodemographic factors, vitamin K intake, clinical factors, and genetic variations.The overall incidence of major hemorrhagic events was 7.6/100 person-years (p-yrs, 95% confidence interval [CI] 6.4-8.9) in our population. The incidence was lower for physically active patients (5.6/100 p-yrs, 95% CI 4.2-7.2) than in inactive patients (10.3/100 p-yrs, 95% CI 8.2-12.9, p=0.0004). Active patients had a 38% lower risk of hemorrhage (hazard ratio 0.62, 95% CI 0.42-0.98, p=0.03) compared with inactive patients.

CONCLUSIONS

Regular physical activity is associated with higher warfarin dose requirements and lower risk of hemorrhage. The influence of physical activity on drug response needs to be further explored, and the mechanisms through which it exerts these effects need to be elucidated

O grau de melhora na função das células progenitoras endoteliais derivadas da medula óssea é dependente do volume de treinamento físico aeróbio

INTRODUÇÃO: A angiogênese muscular esquelética induzida pelo treinamento físico aeróbio (TF) é determinante na melhora da capacidade aeróbia. Entre os fatores envolvidos, as células progenitoras endoteliais (CPE) derivadas da medula óssea são descritas por promoverem o reparo vascular e a angiogênese. Embora o papel do TF sobre os parâmetros das CPE tenha sido investigado, pouco se conhece sobre os efeitos de diferentes volumes de TF sobre a função das CPE da medula óssea, alterações metabólicas e capilarização muscular. OBJETIVO: Testar a hipótese de que o TF melhore a função das CPE da medula óssea, acompanhada por maior capilarização e capacidade oxidativa muscular dependentes do aumento de volume de TF. MÉTODOS: Vinte e uma ratas Wistar foram divididas em três grupos: sedentário controle (SC), treinado protocolo 1 (P1), treinado protocolo 2 (P2). P1: o treinamento de natação consistiu de 60 min, 1x/dia, cinco dias/semana/10 semanas, com 5% de sobrecarga corporal. P2: o mesmo de P1 até a oitava semana, na nona semana os animais treinaram 2x/dia e na 10ª semana 3x/dia. RESULTADOS: O TF promoveu bradicardia de repouso, aumento da tolerância ao esforço, do consumo de oxigênio de pico e da atividade da enzima citrato sintase muscular no grupo P1, sendo estas adaptações mais exacerbadas no grupo P2, indicando que a condição aeróbia foi mais proeminente com este TF. O TF melhorou a função das CPE da medula óssea em P1, sendo ainda maior esta resposta no grupo P2. Em paralelo, observa-se também um aumento no número de capilares dependentes do volume de TF. CONCLUSÃO: Estes resultados sugerem que a medula óssea como o principal reservatório de CPE é influenciada por diferentes volumes de TF, sendo possivelmente responsável pelo maior rendimento físico observado mediante uma maior mobilização endógena de CPE, participantes ativas no processo de angiogênese muscular induzido pelo TF.

Effects of exercise training on coronary collateralization and control of collateral resistance

Coronary collateral vessels serve as a natural protective mechanism to provide coronary flow to ischemic myocardium secondary to critical coronary artery stenosis. The innate collateral circulation of the normal human heart is typically minimal and considerable variability occurs in extent of collateralization in coronary artery disease patients. A well-developed collateral circulation has been documented to exert protective effects upon myocardial perfusion, contractile function, infarct size, and electrocardiographic abnormalities. Thus therapeutic augmentation of collateral vessel development and/or functional adaptations in collateral and collateral-dependent arteries to reduce resistance into the ischemic myocardium represent a desirable goal in the management of coronary artery disease. Tremendous evidence has provided documentation for the therapeutic benefits of exercise training programs in patients with coronary artery disease (and collateralization); mechanisms that underlie these benefits are numerous and multifaceted, and currently under investigation in multiple laboratories worldwide. The role of enhanced collateralization as a major beneficial contributor has not been fully resolved. This topical review highlights literature that examines the effects of exercise training on collateralization in the diseased heart, as well as effects of exercise training on vascular endothelial and smooth muscle control of regional coronary tone in the collateralized heart. Future directions for research in this area involve further delineation of cellular/molecular mechanisms involved in effects of exercise training on collateralized myocardium, as well as development of novel therapies based on emerging concepts regarding exercise training and coronary artery disease.