SIRT6 protects cardiomyocytes against ischemia/reperfusion injury by augmenting FoxO3α-dependent antioxidant defense mechanisms.

SIRT6, a member of the NAD(+)-dependent class III deacetylase sirtuin family, has been revealed to play important roles in promoting cellular resistance against oxidative stress. The formation of reactive oxygen species (ROS) and oxidative stress are the crucial mechanisms underlying cellular damage and dysfunction in cardiac ischemia/reperfusion (I/R) injury, but the role of SIRT6 in I/R-induced ROS and oxidative stress is poorly understood. In this study, by using heterozygous SIRT6 knockout (SIRT6(+/-)) mice and cultured neonatal cardiomyocyte models, we investigated how SIRT6 mediates oxidative stress and myocardial injury during I/R. Partial knockout (KO) of SIRT6 aggravated myocardial damage, ventricular remodeling, and oxidative stress in mice subjected to myocardial I/R, whereas restoration of SIRT6 expression by direct cardiac injection of adenoviral constructs encoding SIRT6 reversed these deleterious effects of SIRT6 KO in the ischemic heart. In addition, partial deletion of the SIRT6 gene decreased myocardial functional recovery following I/R in a Langendorff perfusion model. Similarly, the protective effects of SIRT6 were also observed in cultured cardiomyocytes following hypoxia/reoxygenation. Intriguingly, SIRT6 was noticed to up-regulate AMP/ATP and then activate the adenosine 5'-monophosphate-activated protein kinase (AMPK)-forkhead box O3α (FoxO3α) axis and further initiated the downstream antioxidant-encoding gene expression (manganese superoxide dismutase and catalase), thereby decreasing cellular levels of oxidative stress and mediating cardioprotection in the ischemic heart. These results suggest that SIRT6 protects the heart from I/R injury through FoxO3α activation in the ischemic heart in an AMP/ATP-induced AMPK-dependent way, thus upregulating antioxidants and suppressing oxidative stress.

Patients Aged 80 Years or Older are Encountered More Potentially Inappropriate Medication Use.

BACKGROUND: Polypharmacy and potentially inappropriate medications (PIMs) are prominent prescribing issues in elderly patients. This study was to investigate the different prevalence of PIM use in elderly inpatients between 65-79 years of age and 80 years or older, who were discharged from Geriatric Department in West China Hospital. METHODS: A large-scale cohort of 1796 inpatients aged 65 years or over was recruited. Respectively, 618 patients were 65-79 years and 1178 patients were 80 years or older. Updated 2012 Beers Criteria by the American Geriatric Society was applied to assess the use of PIM among the investigated samples. RESULTS: A review of the prescribed medications identified 686 patients aged 80 years or older consumed at least one PIM giving a rate of 58.2%. Conversely, 268 (43.4%) patients aged 65-79 years consumed at least one PIM (χ2 = 40.18, P < 0.001). Patients aged 80 years or older had higher hospitalization expenses, length of stay, co-morbidities, medical prescription, and mortality than patients aged 65-79 years (all with P < 0.001). Patients aged 80 years or older were prescribed with more benzodiazepines, drugs with strong anticholinergic properties, megestrol, antipsychotics, theophylline, and aspirin. In multiple regression analysis, PIM use was significantly associated with female gender, age, number of diagnostic disease, and number of prescribed medication. CONCLUSIONS: The finding from this study revealed that inpatients aged 80 years or older encountered more PIM use than those aged 65-79 years. Anticholinergic properties, megestrol, antipsychotics, theophylline, and aspirin are medications that often prescribed to inpatients aged 80 years or older. Doctors should carefully choose drugs for the elderly, especially the elderly aged 80 years or older.

Ghrelin inhibits doxorubicin cardiotoxicity by inhibiting excessive autophagy through AMPK and p38-MAPK.

Doxorubicin (DOX) is a wide spectrum antitumor drug, but its clinical application is limited by the cardiotoxicity. Ghrelin, a multi-functional peptide hormone with metabolic regulation in energy homeostasis, plays important roles in cardiovascular protection. Now, the underlying mechanisms of ghrelin against DOX-induced cardiomyocyte apoptosis and atrophy are still not clear. In the present study, we revealed an autophagy-dependent mechanism involved in ghrelin's protection against DOX-induced cardiomyocyte death and size decrease. We observed that DOX insult induced remarkable mortality and cardiac dysfunction in mice, and increase in LDH leakage, cardiomyocyte apoptosis and decrease in cell viability and size in mouse hearts and H9c2 cell cultures, which were effectively improved by ghrelin supplement. We further observed that the strong autophagy stirred by DOX exposure was paralleling with the serious apoptosis and size decrease in cardiomyocytes. Ghrelin, like an autophagy inhibitor, 3-MA, inhibited the DOX-induced autophagy and attenuated cardiomyocyte apoptosis and size decrease. Furthermore, ghrelin significantly reduced the intercellular oxidative stress level, a strong autophagy trigger, partly by augmenting the expression and activities of the endogenous anti-oxidative enzymes. After the further investigation in the post signaling pathways of ghrelin receptors in H9c2 cells, including ERK, p38/MAPK, JNK, AMPK and Akt, we observed that ghrelin supplement only reduced the DOX-activated AMPK and augmented the DOX-down regulated p38-MAPK and mTOR phosphorylation. Our results indicated that ghrelin effectively improved the cardiomyocyte survival and size maintenance by suppressing the excessive autophagy through both ROS inhibition and mTOR induction through suppressing AMPK activity and stimulating p38-MAPK activity.