The outbreak of coronavirus named COVID-19, initially identified in Wuhan, China in December 2019, has spread rapidly at the global scale. Most countries have rapidly stopped almost all activities including industry, services and transportation of goods and people, thus decreasing air pollution in an unprecedented way, and providing a unique opportunity to study air pollutants. While satellite data have provided visual evidence for the global reduction in air pollution such as nitrogen dioxide (NO 2) worldwide, precise and quantitative information is missing at the local scale. Here we studied changes in particulate matter (PM 2.5 , PM 10), carbon monoxide (CO), NO 2 , sulfur dioxide (SO 2) and ozone (O 3) at 10 urban sites in Hangzhou, a city of 7.03 million inhabitants, and at 1 rural site, before city lockdown, January 1-23, during city lockdown, January 24-February 15, and during resumption, February 16-28, in 2020. Results show that city lockdown induced a sharp decrease in PM 2.5 , PM 10 , CO, and NO 2 concentrations at both urban and rural sites. The NO 2 decrease is explained by reduction in traffic emissions in the urban areas, and by lower regional transport in rural areas during lockdown, as expected. SO 2 concentrations decreased from 6.3 to 5.3 μg m −3 in the city, but increased surprisingly from 4.7 to 5.8 μg m −3 at the rural site: this increase is attributed both to higher coal consumption for heating and emissions from traditional fireworks of the Spring Eve and Lantern Festivals during lockdown. Unexpectedly, O 3 concentrations increased by 145% from 24.6 to 60.6 μg m −3 in the urban area, and from 42.0 to 62.9 μg m −3 in the rural area during the lockdown. This finding is explained by the weakening of chemical titration of O 3 by NO due to reductions of NO x fresh emissions during the non-photochemical reaction period from 20:00 PM to 9:00 AM (local time). During the lockdown, compared to the same period in 2019, the daily average concentrations in the city decreased by 42.7% for PM 2.5 , 47.9% for PM 10 , 28.6% for SO 2 , 22.3% for CO and 58.4% for NO 2 , which is obviously explained by the absence of city activities. Overall, we observed not only the expected reduction in some atmospheric pollutants (PM, SO 2 , CO, NO 2), but also unexpected increases in SO 2 in the rural areas and of ozone (O 3) in both urban and rural areas, the latter being paradoxically due to the reduction in nitrogen oxide levels. In other words, the city lockdown has improved air quality by reducing PM 2.5 , PM 10 , CO, and NO 2 , but has also decreased air quality by augmenting O 3 and SO 2 .

Reducing oxidative stress is a crucial therapeutic strategy for ameliorating diabetic myocardial ischemia/reperfusion (MI/R) injury. Honokiol (HKL) acts as an effective cardioprotective agent for its strong antioxidative activity. However, its roles and underlying mechanisms against MI/R injury in type 1 diabetes (T1D) remain unknown. Since SIRT1 and Nrf2 are pivotal regulators in diabetes mellitus patients suffering from MI/R injury, we hypothesized that HKL ameliorates diabetic MI/R injury via the SIRT1-Nrf2 signaling pathway. Streptozotocin-induced T1D rats and high-glucose-treated H9c2 cells were exposed to HKL, with or without administration of the SIRT1 inhibitor EX527, SIRT1 siRNA, or Nrf2 siRNA, and then subjected to I/R operation. We found that HKL markedly improved the postischemic cardiac function, decreased the infarct size, reduced the myocardial apoptosis, and diminished the reactive oxygen species generation. Intriguingly, HKL remarkably activated SIRT1 signaling, enhanced Nrf2 nuclear translocation, increased antioxidative signaling, and decreased apoptotic signaling. However, these effects were largely abolished by EX527 or SIRT1 siRNA. Additionally, our cellular experiments showed that Nrf2 siRNA blunted the cytoprotective effects of HKL, without affecting SIRT1 expression and activity. Collectively, these novel findings indicate that HKL abates MI/R injury in T1D by ameliorating myocardial oxidative damage and apoptosis via the SIRT1-Nrf2 signaling pathway.

Hyperglycemia-induced oxidative stress and fibrosis play a crucial role in the development of diabetic cardiomyopathy (DCM). Tetrahydrocurcumin (THC), a major bioactive metabolite of natural antioxidant curcumin, is reported to exert even more effective antioxidative and superior antifibrotic properties as well as anti-inflammatory and antidiabetic abilities. This study was designed to investigate the potential protective effects of THC on experimental DCM and its underlying mechanisms, pointing to the role of high glucose-induced oxidative stress and interrelated fibrosis. In STZ-induced diabetic mice, oral administration of THC (120 mg/kg/d) for 12 weeks significantly improved the cardiac function and ameliorated myocardial fibrosis and cardiac hypertrophy, accompanied by reduced reactive oxygen species (ROS) generation. Mechanically, THC administration remarkably increased the expression of the SIRT1 signaling pathway both in vitro and in vivo, further evidenced by decreased downstream molecule Ac-SOD2 and enhanced deacetylated production SOD2, which finally strengthened antioxidative stress capacity proven by repaired activities of SOD and GSH-Px and reduced MDA production. Additionally, THC treatment accomplished its antifibrotic effect by depressing the ROS-induced TGFβ1/Smad3 signaling pathway followed by reduced expression of cardiac fibrotic markers α-SMA, collagen I, and collagen III. Collectively, these finds demonstrated the therapeutic potential of THC treatment to alleviate DCM mainly by attenuating hyperglycemia-induced oxidative stress and fibrosis via activating the SIRT1 pathway.

BackgroundRecent studies have shown Growth differentiation factor–15 (GDF-15) that is a member of the transforming growth factor β (TGF-β) superfamily might be a potential predictive cytokine for the prognosis of Acute coronary syndrome (ACS). However, there are discrepancies in these studies.MethodsPublication searches of the PubMed/Medline and EMBASE databases were performed without any time or ethnicity restrictions. The inclusion and exclusion criteria, when clear, were addressed. Random effects models were used for all analyses. Publication bias was tested using funnel plots and the Egger test.ResultsWe identified eight eligible studies that provided mortality data. Five of these studies provided recurrent myocardial infarction (MI) data. The maximal duration of follow-up ranged from 6 months to 6 years. A significant association was found between the patients with the highest and lowest GDF-15 levels (overall analyses) in terms of mortality (p < 0.00001; RR = 6.08; 95 % CI = 4.79–7.71) and recurrent MI (p < 0.00001; RR = 1.76; 95 % CI = 1.49–2.07). We also found significant associations between the subgroup analyses stratified by ACS types, cutoff points and follow-up durations (p < 0.001). The combined hazard ratio was high for GDF-15 to ACS (HR = 1.656, 95 % CI = 1.467–1.871).ConclusionHigh plasma GDF-15 levels are associated with an increased risk of mortality and recurrent MI in patients with ACS.Electronic supplementary materialThe online version of this article (doi:10.1186/s12872-016-0250-2) contains supplementary material, which is available to authorized users.