Daily oral administration of probiotics engineered to constantly secrete short-chain fatty acids effectively prevents myocardial injury from subsequent ischemic heart disease.

AIM: Given the extremely limited regeneration potential of the heart, one of the most effective strategies to reduce the prevalence and mortality of coronary artery disease is prevention. Short-chain fatty acids (SCFAs), which are by-products of beneficial probiotics, have been reported to possess cardioprotective effects. Despite their beneficial roles, delivering SCFAs and maintaining their effective concentration in plasma present major challenges. Therefore, in the present study, we aimed to devise a strategy to prevent coronary heart disease effectively by using engineered probiotics to continuously release SCFAs in vivo. METHODS AND RESULTS: We engineered a novel probiotic cocktail, EcN_TL, from the commercially available Escherichia coli Nissle 1917 strain to continuously secrete SCFAs by introducing the propionate and butyrate biosynthetic pathways. Oral administration of EcN_TL enhanced and maintained an effective concentration of SCFAs in the plasma. As a preventative strategy, we observed that daily intake of EcN_TL for 14 days prior to ischemia-reperfusion injury significantly reduced myocardial injury and improved cardiac performance compared to EcN administration. We uncovered that EcN_TL's protective mechanisms included reducing neutrophil infiltration into the infarct site and promoting the polarization of wound-healing macrophages. We further revealed that SCFAs at plasma concentration protected cardiomyocytes from inflammation by suppressing the NF-κB activation pathway. CONCLUSIONS: These data provide strong evidence to support the use of SCFA-secreting probiotics to prevent coronary heart disease. Since SCFAs also play a key role in other metabolic diseases, EcN_TL can potentially be used to treat a variety of other diseases.

Study of natural attenuation after acid in situ leaching of uranium mines using isotope fractionation and geochemical data.

Acid in situ leaching (AISL) is a subsurface mining approach suitable for low-grade ores which does not generate tailings, and has been adopted widely in uranium mining. However, this technique causes an extremely high concentration of contaminants at post-mining sites and in the surroundings soon after the mining ceases. As a potential AISL remediation strategy, natural attenuation has not been studied in detail. To address this problem, groundwater collected from 26 wells located within, adjacent, upgradient, and downgradient of a post-mining site were chosen to analyze the fate of U(VI), SO42-, δ34S, and δ238U, to reveal the main mechanisms governing the migration and attenuation of the dominant contaminants and the spatio-temporal evolutions of contaminants in the confined aquifer of the post-mining site. The δ238U values vary from -0.07 ‰ to 0.09 ‰ in the post-mining site and from -1.43 ‰ to 0.03 ‰ around the post-mining site. The δ34S values were found to vary from 3.3 ‰ to 6.2 ‰ in the post-mining site and from 6.0 ‰ to 11.0 ‰ around the post-mining site. Detailed analysis suggests that there are large differences between the range of isotopic composition variation and the range of pollutants concentration distribution, and the estimated Rayleigh isotope fractionation factor is 0.9994-0.9997 for uranium and 1.0032-1.0061 for sulfur. The isotope ratio of uranium and sulfur can be used to deduce the migration history of the contaminants and the irreversibility of the natural attenuation process in the anoxic confined aquifer. Combining the isotopic fractionation data for U and S with the concentrations of uranium and sulfate improved the accuracy of understanding of reducing conditions along the flow path. The study also indicated that as long as the geological conditions are favorable for redox reactions, natural attenuation could be used as a cost-effective remediation scheme.

Platelet activation and immune response in diabetic microangiopathy.

BACKGROUND: Diabetes can lead to serious pathological changes in the microvascular system, which in turn leads to functional damage of related tissues that affects the quality of life of patients. The mechanism of microcirculation disturbance in diabetes is not well understood; however, the inflammatory damage and dysgenesis of blood vessels based on oxidative and hyperosmotic stress is considered to be a key factor. In addition, with in-depth studies of platelet function, the study of platelet inflammatory function has become popular in recent years. OBJECTIVE: The present manuscript reviews the new knowledge of platelet immune inflammatory function and the mechanism of diabetic microangiopathy, and emphasizes the relationship between them. CONCLUSION: The nuclear factor-κB (NF-κB) pathway has always been regarded as a typical pro-inflammatory signaling pathway in different nucleated cells, and NF-κB is also expressed in platelets. Although the signaling pathway of NF-κB in platelets is not completely understood, numerous studies have confirmed its function in platelet immune inflammation. The signaling pathway of the development of diabetic microangiopathy is partially cross-linked with the platelet NF-κB pathway. In addition, platelets can release various chemokines to aggravate vascular endothelial cell injury, indicating that platelets may serve a key role in the mechanism of diabetic microangiopathy.

Distribution of radon and risk assessment of its radiation dose in groundwater drinking for village people nearby the W-polymetallic metallogenic district at Dongpo in southern Hunan province, China.

Radon in the household water (especially groundwater) which is an important source of indoor radon, has become a potential health hazard to residents. In this study, radon concentrations in groundwater sampled from five villages near Dongpo W-polymetallic metallogenic region were measured using RAD-7 detector with RAD H2O accessory, and the effect of regional geology and mineralization on radon concentration in groundwater was studied. In addition, we also estimated the radiation doses received by people via ingestion of radon in water and inhalation of the radon from the indoor air while using water. The results show that the radon concentration in groundwater samples varies from 1.29 Bq L-1 to 31.31 Bq L-1 with 10.47 Bq L-1 on average, and about 31.3% of the groundwater samples analyzed have a higher radon concentration than the maximum contaminant level of 11.1 Bq L-1 recommended by United States Environmental Protection Agency (USEPA). The relatively high radon level in groundwater can be attributed to a relatively high uranium background produced by the magmatic activity and magmatic-hydrothermal system. The values of annual effective dose (AEDing) due to ingestion of radon in groundwater range from 0.002 mSv y-1 to 0.055 mSv y-1, 0.005 mSv y-1 to 0.11 mSv y-1 and 0.008 mSv y-1 to 0.188 mSv y-1 for adult, child and infant respectively. The values of annual effective dose due to the inhalation of radon released from water are 63.6, 15.4 and 3.8 times of those through the ingestion of radon in groundwater by the adults, children and infants, respectively. In addition, the values of estimated total annual effective doses are 0.020-0.480 mSv y-1, 0.017-0.406 mSv y-1 and 0.020-0.484 mSv y-1 for adult, child and infant, respectively. These values are much lower than the reference dose level of 1 mSv y-1 recommended by World Health Organization (WHO) and United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR).

The effect of laterite density on radon diffusion behavior.

Radon generated in porous media such as soils and rocks migrates into indoor and outdoor air mainly by diffusion, possessing significant hazards to human health. In order to reduce these hazards of radon, it is of great importance to study the diffusion behavior of radon. In this study, we systematically measured the radon diffusion coefficient of laterite with the density ranging from 0.917gcm-3 to 2.238gcm-3, and studied the effect of laterite density on the radon diffusion. The results show that the radon diffusion coefficient of the laterite generally decreases with the increasing laterite density. In addition, three possible relationships between the radon diffusion coefficient and the laterite density are found out as follows: (1) the linear correlation with a slope of -4.48 × 10-6 for laterite with density ranging from 0.917 to 1.095gcm-3, (2) the exponential correlation for laterite with density from 1.095 to 1.63gcm-3, (3) linear correlation with a slope of -3.1 × 10-7 for laterite with density from 1.63 to 2.238gcm-3. The complex relationship between the radon diffusion coefficient and density is caused by the change of porosity and tortuosity of the laterite. Therefore, we suggest that a suitable density should be adopted while using the laterite to effectively cover uranium tailings or economically produce building materials that can curb the radon exhalation.

Fractal Theory and Field Cover Experiments: Implications for the Fractal Characteristics and Radon Diffusion Behavior of Soils and Rocks.

Radon diffusion and transport through different media is a complex process affected by many factors. In this study, the fractal theories and field covering experiments were used to study the fractal characteristics of particle size distribution (PSD) of six kinds of geotechnical materials (e.g., waste rock, sand, laterite, kaolin, mixture of sand and laterite, and mixture of waste rock and laterite) and their effects on radon diffusion. In addition, the radon diffusion coefficient and diffusion length were calculated. Moreover, new formulas for estimating diffusion coefficient and diffusion length functional of fractal dimension d of PSD were proposed. These results demonstrate the following points: (1) the fractal dimension d of the PSD can be used to characterize the property of soils and rocks in the studies of radon diffusion behavior; (2) the diffusion coefficient and diffusion length decrease with increasing fractal dimension of PSD; and (3) the effectiveness of final covers in reducing radon exhalation of uranium tailings impoundments can be evaluated on the basis of the fractal dimension of PSD of materials.