Oxidative stress assessed in saliva from patients with acute myocardial infarction: a preliminary study

Existe evidencia que permite establecer una asociación entre la generación de especies reactivas del oxígeno y el daño tisular en el síndrome coronario agudo. El objetivo de este trabajo fue detectaren saliva de pacientes con infarto agudo de miocardio (IAM), la presencia de reactantes de estrés oxidativo a las 24 y 48 horas. Materiales y métodos: se efectuó un estudio prospectivo de comparación entre pacientes con IAM con supradesnivel del segmento STen el electrocardiograma y sujetos sin patología clínica evidente. Laproducción de especies reactivas de oxígeno fue evaluada mediantela tasa de oxidación de la 2’7’ diacetato de diclorohidrofluoreceina (DCFH-DA) y la actividad antioxidante de la enzima catalasa (CAT) en saliva de pacientes con IAM a las 24 y 48 h de producido el síndrome coronario agudo. Simultáneamente, se determinaron en suero los biomarcadores diagnósticos de IAM. Resultados: se incorporaron10 pacientes con IAM con supradesnivel del ST que fueron comparados con 10 sujetos del grupo control. La edad promedio fue 67.8 ± 11.1 vs 48.7 ± 4.1 años, respectivamente (p<0.001); el 60 por ciento vs 50 por ciento fueron hombres sin diferencias entre ambos grupos (p>0.05). La media de la velocidad de oxidación de la DCFH-DA fue mayor a las 24 h en los pacientes con IAM (p=0.004). Estas diferencias semantuvieron a las 48 h del infarto sin cambios significativos. No se encontraron diferencias en las medias de actividad de la enzima catalasa entre IAM y control (p>0.05). Se encontró una relación entre CAT48 y DCFH-DA48 (r=0.39; p=0.053). Conclusiones: Enesta población se han detectado reactantes de estrés oxidativo ensaliva de pacientes con IAM. Relevancia clínica: nuevos estudios con mayor número de casos serán necesarios para confirmar estas observaciones y evaluar la utilidad de la saliva en el diagnóstico,evolución y pronóstico del síndrome coronario agudo.

There is evidence that acute myocardial infarction (AMI) is asso-ciated with increasing production of reactive oxygen species andtissue injury. The aim of this study was to assess the presence ofoxidative stress indices in saliva 24 and 48h after AMI. Materialsand methods: We designed a prospective study comparing sali-vary levels of biomarkers of oxidative stress in patients with AMIwith elevation of the ST segment in electrocardiogram versus clin-ically healthy subjects. Oxidative stress indices including the rateof oxidation of 2’7’ dichlorohydrofluorescein diacetate (DCFH-DA) and the activity of the antioxidant enzyme catalase (CAT)were evaluated in saliva from patients with AMI at 24 and 48hours. At each sampling time, blood was drawn for serum mark-ers of myocardial infarction. Results: This study included tenpatients with acute ST-segment elevation myocardial infarctionand ten clinically healthy controls. Mean age was 67.8 ± 11.1 vs.48.7 ± 4.1 years (p<0.001) and gender was 60% male vs. 50%(p>0.05) for AMI vs. controls, respectively. Our results demon-strated an increase in the rate of oxidation of DCFH-DA in themyocardial infarction group as compared with controls (p=0.004),which remained unchanged at 48h. There was no difference insalivary catalase activity between controls and AMI subjects at24h or at 48h post-diagnosis (p=0.157). The relationship betweenCAT48and DCFH-DA48was fairly significant (r=0.39; p=0.053).Conclusion: This preliminary study showed that biomarkers ofoxidative stress are detectable in saliva of patients with acutemyocardial infarction. Clinical Relevance: Future studies using alarger population are needed to confirm these observations and toexplore the possibility of using the saliva to monitor evolving diag-nosis and prognosis in acute coronary syndrome.

Effect of oxidative stress on iron reduction rates in biologica systems

The aim of the present study was to characterize the effect of oxidative stress on iron reduction rates in biological systems. The tested oxidative stress conditions included acute iron overload in rats, UV-B irradiation in algae cultures and leaves, and paraquat treatment and aging in soybean embryonic axes upon imbibition. Treatment of rats with iron-dextran resembles hemochromatosis secondary to iron loading anemias and high oral iron intake. A significant increase was detected in both iron deposits in liver cells and microsomal iron content after 4 h of a single dose of iron-dextran, however, the iron reduction rate was not affected in the presence of either NADPH or NADH as cofactor. In vivo iron reduction rate in Chlorella vulgaris cells was not significantly different in log and stationary phases. Exposure of the cultures to UV-B doses of O.8 and 4.4 kJ/m2 increased iron reduction rate by intact cells from 6 (control) to 32 and 64 nmol/lO(9) cell.min, respectively. UV-B exposure of soybean leaves lead to a significant increase in leakage of electrolytes probably due to membrane damage, however, iron reduction rates were not significantly different in control and irradiated leaves. Soybean embryonic axes incubated in the presence of paraquat or axes from aged seeds showed a significant decrease in fresh weight of the axes after 30 h of development. Moreover, the consistent increase in iron reduction rates measured in control axes during the imbibition period was inhibited either in the presence of paraquat or with aged embryonic axes. The data presented here suggest that iron reduction does not seem a universal early index of oxidative damage in biological systems, in spite of its crucial role in oxidative metabolism.