Metabolomic reveals the responses of sludge properties and microbial communities to high nitrite stress in denitrifying phosphorus removal systems.

Nitrite, as an electron acceptor, plays a good role in denitrifying phosphorus removal (DPR); however, high nitrite concentration has adverse affects on sludge performance. We investigated the precise mechanisms of responses of sludge to high nitrite stress, including surface characteristics, intracellular and extracellular components, microbial and metabolic responses. When the nitrite stress reached 90 mg/L, the sludge settling performance was improved, but the activated sludge was aging. FTIR and XPS analysis revealed a significant increase in the hydrophobicity of the sludge, resulting in improve settling performance. However, the intracellular carbon sources synthesis was inhibited. In addition, the components in the tightly bound extracellular polymeric substances (TB-EPS) of sludge were significantly reduced and indicated the disturb of metabolism. Notably, Exiguobacterium emerged as a new genus when face high nitrite stress that could maintaining survival in hostile environments. Moreover, metabolomic analysis demonstrated strong biological response to nitrite stress further supported above results that include the inhibited of carbohydrate and amino acid metabolism. More importantly, some lipids (PS, PA, LysoPA, LysoPC and LysoPE) were significantly upregulated that related enhanced membrane lipid remodeling. The comprehensive analyses provide novel insights into the high nitrite stress responses mechanisms in activated sludge systems.

Predictive value of the serum uric acid to high-density lipoprotein cholesterol ratio for culprit plaques in patients with acute coronary syndrome.

BACKGROUND: Hyperuricemia and low level of high-density lipoprotein cholesterol (HDL-C) are both risk factors for coronary artery disease (CAD). The uric acid to HDL-C ratio (UHR) has recently been identified as a new inflammatory and metabolic biomarker. However, the relationship between the UHR and coronary culprit plaques has not been fully investigated in patients with acute coronary syndrome (ACS). METHODS: A total of 346 patients with ACS were enrolled in this study. Culprit lesion characteristics were assessed by optical coherence tomography (OCT). Logistic regression and linear correlation analyses were performed to assess the association between the UHR and culprit plaques. The predictive value of the UHR was investigated by receiver operating characteristic (ROC) curve analysis. RESULTS: The percentages of typical culprit plaques, including ruptures, erosions and thrombi, were greater in the high-UHR subgroup than those in the low-UHR subgroup. A positive relationship was also found between the UHR and diameter stenosis (r = 0.160, P = 0.003) and between the UHR and area stenosis (r = 0.145, P = 0.007). The UHR was found to be independently associated with plaque rupture, erosion and thrombus. Furthermore, ROC analysis suggested that the UHR had a better predictive value than low-density lipoprotein cholesterol. CONCLUSIONS: An elevated UHR level was independently related to the occurrence rate of culprit plaques. The UHR is a simple and easily acquired parameter for detecting culprit plaques in patients with ACS.

Exosome-based WTAP siRNA delivery ameliorates myocardial ischemia-reperfusion injury.

Myocardial ischemia/reperfusion (MI/R) injury is the primary cause of postischemicheartfailure. The increased expression of Thioredoxin-interacting protein (TXNIP) has been implicated in MI/R injury, although the detailed mechanism remains incompletely understood. In the present study, we observed the up-regulation of the m6A mRNA methylation complex component Wilms' tumor 1-associating protein (WTAP) in MI/R mice, which led to the m6A modification of TXNIP mRNA and an increase in mRNA abundance. Knock-down of WTAP resulted in a significant reduction in the m6A level of TXNIP mRNA and down-regulated TXNIP expression. Moreover, exosomes engineered with ischemic myocardium-targeting peptide (IMTP) were able to deliver WTAP siRNA into ischemic myocardial tissues, resulting in a specific gene knockdown and myocardial protection. In summary, our findings demonstrate that the WTAP-TXNIP regulatory axis plays a significant role in postischemicheartfailure, and the use of engineered exosomes targeting the ischemic heart shows promise as a strategy for siRNA therapy to protect the heart from injury.

Identification of Fibrotic Biomarkers Associated with Macrophages in Diabetic Nephropathy.

BACKGROUND Diabetic nephropathy (DN) is the main cause of end-stage renal disease. Renal fibrosis is an important pathological feature of kidney injury, and the therapeutic means are very limited. The functions of macrophages play important roles in renal fibrosis. There is a complicated link between altered immune metabolism and oxidative stress. Hence, we designed this study to identify the oxidative stress- and macrophage-relevant biomarkers reflecting fibrosis in DN. MATERIAL AND METHODS Differential expression analysis was performed based on the GSE96804 dataset. xCell and weighted gene co-expression network analysis were used to determine the distinctions in infiltrating immune cells between DN and control specimens. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were conducted. A protein-protein interaction network was constructed to identify the hub genes. Hub genes were validated in an external dataset, GSE30528, and cell models. RESULTS MMP2, CASP3, and HIF-1alpha were identified as biomarkers, which were upregulated in the DN group and positively correlated with the infiltration of macrophages and M1 macrophages. In vitro, the 3 genes were highly expressed in murine MPC5 cells treated with high glucose and human THP-1 macrophages treated with advanced glycation end products. CONCLUSIONS Our results provided biomarkers for predicting the fibrotic progression of DN and confirmed that MMP2, CAPS3, and HIF-1alpha have good diagnostic value. They might be involved in the progression of DN fibrosis by regulating oxidative stress and macrophage recruitment or polarization.

In-depth potential mechanism of combined demulsification pretreatments (isopropanol ultrasonic pretreatments and Ca2+ flow additions) during aqueous enzymatic extractions of Camellia oils.

Emulsification is the practical limitation of aqueous enzymatic extractions of Camellia oils. This study aimed to investigate the influence and demulsification mechanisms of isopropanol ultrasonic pretreatments and Ca2+ additions on aqueous enzymatic extractions of Camellia oils. Combining isopropanol ultrasonic pretreatments with Ca2+ flow additions obtained the highest free oil recovery (78.03 %) and lowest emulsion content (1.5 %). Results indicated that the superior demulsification performance originated from the decrease in emulsion stabilities and formations. First, demulsification pretreatments reduced the oil (14.69 %) and solid (13.21 %) fractions in emulsions to decrease the stability of as-formed emulsions. Meanwhile, isopropanol ultrasonic pretreatments extracted tea saponins (0.38 mg/mL) and polysaccharides (0.23 mg/mL), while Ca2+ combined with protein isolates (5.82 mg/mL), tea saponins (7.48 mg/mL) and polysaccharides (0.78 mg/mL) to form precipitates and reduce emulsion formation. This work could promote the practical application of aqueous enzymatic extractions of Camellia oils and enlighten the rise of advanced demulsification pretreatments.

Removal of Escherichia coli from domestic sewage using biological sand filters: Reduction effect and microbial community analysis.

The recycling of sewage is an economical option to solve the water resource pressure. However, to avoid health risks to humans, pathogens in sewage must be removed before reuse. In this study, a biological sand filter (BSF) was used to remove pathogen indicator Escherichia coli (E. coli) from sewage. The biolayer (schmutzdecke layer) formation process of BSFs, operation performance, factors affecting E. coli removal and microbial community structure were evaluated. The results of schmutzdecke layer culture showed that a large number of microorganisms were attached to the upper medium of BSFs. At the same time, the BSFs could reduce both conventional contaminants and E. coli. The E. coli removal experiments revealed that the removal rate of E. coli was about 96.1% at higher effective medium depth (50 cm), the removal rate was about 95% when set hydraulic loading rate (HLR) to 0.16 m3/m2/h and the removal efficiency reached 93.6% at lower influent bacteria concentration. Finally, the microbial community analysis indicated that different BSFs had similar microbial structure, and the microbial abundance in the schmutzdecke layer was higher than that in the bottom layer in the same BSFs. Besides, Biological action played a significant role in the removal of E. coli, including the bacteriolysis of Bdellovibrio and the competition between other bacteria and E. coli. In summary, BSF was a promising technology for removing E. coli from sewage.

Application of external carbon source in heterotrophic denitrification of domestic sewage: A review.

The carbon source is essential as an electron donor in the heterotrophic denitrification process. When there is a lack of organic carbon sources in the system, an external carbon source is needed to improve denitrification efficiency. This review compiles the effects of liquid, solid and gaseous carbon sources on denitrification. Sodium acetate has better denitrification efficiency and is usually the first choice for external carbon sources. Fermentation by-products have been demonstrated to have the same denitrification efficiency as sodium acetate. Compared with cellulose-rich materials, biodegradable polymers have better and more stable denitrification performance in solid-phase nitrification, but their price is higher than the former. Methane as a gaseous carbon source is studied mainly by aerobic methane oxidation coupled with denitrification, which is feasible using methane as a carbon source. Liquid carbon sources are better controlled and utilized than solid carbon sources and gaseous carbon sources. In addition, high carbon to nitrogen ratio and hydraulic retention time can promote denitrification, while high dissolved oxygen (DO>2.0 mg L-1) will inhibit the denitrification process. At the same time, high temperature is conducive to the decomposition of carbon sources by microorganisms. This review also considers the advantages and disadvantages of different carbon sources and cost analysis to provide a reference for looking for more economical and effective external carbon sources in the future.

Reduction of Fermentation-Associated Stresses by Straw-Based Soluble Saccharides for Enhancing Ethanol Production.

In this study, the effect of soluble polysaccharides (SPs) derived from agricultural waste, rice straw, on fermentation-associated stresses (temperature and concentrations of glucose and ethanol) was investigated to achieve high-performance ethanol production. The increase in temperature and concentrations of glucose and ethanol significantly inhibited Saccharomyces cerevisiae growth and lowered ethanol fermentation efficiency. Flow cytometric assays indicated that SPs could alleviate membrane permeability damage caused by fermentation-associated stresses. Atomic force microscopy and transmission electron microscopy revealed that fermentation-associated stresses induced cell surface shrinkage, causing a decrease in the cell size, whereas SPs stimulated the formation of extracellular matrices (EMs), which made the cell surface smooth and the cell morphology regular. Cells with EMs induced by SPs could efficiently produce ethanol under severe stresses. As a result, the titer of ethanol in the fermentation with SPs was 1.40-fold (from 26.40 to 36.98 g/L) higher than that in the fermentation without SPs, suggesting the stress-alleviating effect of SPs on ethanol production.

Thioredoxin1 Inactivation Mediates the Impairment of Ischemia-Induced Angiogenesis and Further Injury in Diabetic Myocardium.

Diabetes mellitus (DM)-induced impairment of collateral formation has been demonstrated in subjects with coronary artery disease, which contributes to unfavorable prognosis among diabetic individuals. In our previous studies, thioredoxin1 (Trx1) activity was shown to be decreased in diabetic cardiac tissues, but the reason of Trx1 inactivation and whether it mediates the impaired angiogenesis in ischemic myocardium is still to be identified. As thioredoxin-interacting protein (TXNIP), an endogenous inhibitor of Trx, is overexpressed in DM due to carbohydrate response element within its promoter, we hypothesized that inhibition of Trx1 by enhanced TXNIP expression in endothelial cells may play a role in hyperglycemia-induced impairment of angiogenesis. In the present study, we found that high glucose-mediated increase of TXNIP expression and TXNIP-Trx1 interaction induced the impairment in endothelial cell function and survival, since these detrimental effects are rescued by silencing TXNIP with small interfering RNA. In diabetic mice, TXNIP knockdown or recombinant human Trx1 treatment counteracted the impairment of angiogenesis, alleviated myocardial ischemic injury, and improved survival rate. All these data implicate that TXNIP upregulation and subsequently the increased formation of TXNIP-Trx1 complex is a novel pathologic pathway by which DM induces insufficient angiogenesis and thereby exacerbates myocardial ischemia injury.

Simultaneous production of cellulase and ferulic acid esterase by Penicillium decumbens with rice straw as the sole carbon source.

As well as cellulose and hemicelluloses, rice straw contains phenolic acids. The simultaneous production of monosaccharides and phenolic acids could improve the value of rice straw. In this study, it was confirmed that Penicillium decumbens produces more ferulic acid esterase (FAE) than other cellulase-producing fungi. Cellulose, destarched wheat bran (DSWB), and rice straw were used as carbon sources. Little phenolic acid was released by cellulose- and DSWB-based enzymes during the saccharification of rice straw, whereas rice straw was a favorable carbon source for the simultaneous production of cellulase and FAE. High-performance liquid chromatography showed that during enzyme production, phenolic acids were released from rice straw, and ball-milling affected this release of phenolic acids. Small amounts of phenolic acids induced FAE production. Although the enzymes produced with rice straw showed lower FAE activity than those produced with DSWB, phenolic acids were produced efficiently during the saccharification of rice straw in response to the synergistic effects of cellulase and FAE. Therefore, we suggest that the production of enzymes by P. decumbens on rice straw as the sole carbon source will allow the production of more valuable products from rice straw, making the utilization of rice straw more economic.

Dysregulated Txnip-ROS-Wnt axis contributes to the impaired ischemic heart repair in diabetic mice.

Hyperglycemia-induced impairment of angiogenesis contributes to the unfavorable prognosis of myocardial ischemia in long-standing diabetes mellitus. The underlying mechanism remains largely unknown and therapeutic strategies thereby limited. In the present study, we investigated the possible involvement of thioredoxin-interacting protein (TXNIP) and Wnt/ß-catenin signaling in the context, and their possible relation was also explored. STZ induced diabetic mice were subjected to myocardial infarction (MI). Adenovirus expressing shTXNIP, shCtnnb1 (ß-catenin) driven by VE-Cadherin promoter was administered intramyocardially immediately after MI. Cardiac function, histology, and molecular analyses were performed at predetermined time points. Increased endothelial expression of TXNIP was found in diabetic hearts, which correlated well with reduced nuclear ß-catenin expression, insufficient angiogenesis, aggravated cardiac remodeling, and poor survival. Endothelial-specific knockdown of TXNIP significantly rescued ß-catenin activity, together with increased angiogenesis, preserved cardiac function, and improved survival rate. Moreover, additional knockdown of ß-catenin essentially reversed the beneficial effects of TXNIP downregulation. In vitro, high glucose treatment of human umbilical vein endothelial cells (HUVECs) increased TXNIP levels and ROS concentration, while it reduced ß-catenin activity. Silencing TXNIP or ROS scavenger restored the high glucose induced reduction of Wnt/ß-catenin activity in HUVECs. In addition, either reduction of TXNIP expression or supplementation of exogenous Wnt3a improved the HUVECs quantity and migration under high glucose conditions. Diabetes-induced increase of TXNIP expression in the endothelium contributes to impaired angiogenesis after MI, especially via the elevation of ROS and the impaired Wnt/ß-catenin signaling. Targeting TXNIP-ROS-Wnt is a promising strategy in improving the prognosis.

Nitrative inactivation of thioredoxin-1 increases vulnerability of diabetic hearts to ischemia/reperfusion injury.

Hyperglycemia (HG) significantly increases mortality after myocardial infarction (MI) in patients with and without established diabetes. The specific underlying mechanism remains unknown. The present study attempted to determine whether nitrative inactivation of thioredoxin-1 (Trx-1) may contribute to the exaggerated myocardial ischemia/reperfusion (I/R) injury observed in the hyperglycemic condition. Diabetes was induced by multiple intraperitoneal injections of low-dose streptozotocin (STZ) in mice. After 30 min ischemia by slip-knot ligature of the left anterior descending coronary artery, the myocardium was reperfused for 3h after knot release (for apoptosis, Trx-1-activity, and -nitration determination) or 24h (for cardiac function and infarct size determination). At 10 min before reperfusion, diabetic mice were randomized to receive vehicle, EUK134 (a peroxynitrite scavenger), recombinant human Trx-1 (rhTrx-1), or SIN-1 (a peroxynitrite donor) nitrated Trx-1 (N-Trx-1) administration. Diabetes intensified I/R-induced myocardial injury, evidenced by further enlarged infarct size, increased apoptosis, and decreased cardiac function in diabetic mice. Trx-1 nitrative inactivation was elevated in the diabetic heart before I/R and was further amplified after I/R. Treatment with EUK134 or rhTrx-1, but not N-Trx-1, before reperfusion significantly reduced Trx-1 nitration, preserved Trx-1 activity, attenuated apoptosis, reduced infarct size, and improved cardiac function in diabetic mice. Taken together, our results demonstrated that HG increased cardiac vulnerability to I/R injury by enhancing nitrative inactivation of Trx-1, suggesting that blockade of Trx-1 nitration, or supplementation of exogenous rhTrx-1, might represent novel therapies to attenuate cardiac injury after MI in diabetic patients.

Upregulation of PTEN by peroxynitrite contributes to cytokine-induced apoptosis in pancreatic beta-cells.

Phosphatase and tensin homolog (PTEN), a tumor suppressor gene, by negatively regulating the PI3K-Akt signaling pathway, participates in multiple biological processes such as cell proliferation, apoptosis, differentiation, and migration. Recent studies show that selective deletion of PTEN in pancreatic beta-cells leads to resistance to streptozotocin (STZ)-induced diabetes, but the mechanism is unclear. One major mechanism underlying STZ toxicity is cytokine-mediated beta-cell destruction in which oxidative stress plays a key role. The present study investigated the role of PTEN in cytokine-induced beta-cell apoptosis, and further explored whether oxidative stress, particularly peroxynitrite formation, could regulate PTEN-Akt pathway. Incubation of betaTC-6 cells with cytokine mixture (IL-1beta, TNF-alpha, and IFN-gamma) or exogenous peroxynitrite significantly increased apoptotic cell percentage, elevated PTEN and p-PTEN levels, and inhibited Akt activation. Transfection with PTEN-specific siRNA protected betaTC-6 cells from cytokine or peroxynitrite-mediated cell apoptosis and partially reversed Akt inhibition. Furthermore, nitrotyrosine formation, an indicator of peroxynitrite production, was significantly elevated after cytokine treatment. Preventing peroxynitrite formation by administrating NAC/L: -NMMA, or scavenging peroxynitrite directly by UA, attenuated cytokine-induced PTEN upregulation, Akt inhibition, and beta-cell apoptosis. These findings suggest that peroxynitrite-mediated PTEN upregulation plays an important role in cytokine-induced pancreatic beta-cell apoptosis.

Differential expression of gonadotropin-releasing hormone (GnRH) in pancreas during rat pregnancy.

Many studies have shown that there is a relationship between gonadotropin-releasing hormone (GnRH) and glucose metabolism, but little is known about the effects of GnRH on the pancreas. Our experiment investigated the effect of GnRH on pancreatic islet cell in Sprague-Dawley (SD) rats fed with high-cholesterol diet before and during pregnancy. We found that although high-cholesterol diet led to no significant difference of GnRH mRNA levels in pancreas in nonpregnant rats, it led to a marked increase of those in pregnant rats. Furthermore, in rats fed with standard laboratory chow, no significant differences were apparent in GnRH mRNA levels before and during gestation; however, when fed with high-cholesterol diet, the GnRH mRNA levels increased significantly in pregnant rats. As results indicated both diets could lead to increase of PG mRNA in pancreas of pregnant rats. It is also demonstrated that the GnRH mRNA levels are positively associated with PG mRNA levels. Moreover, our data showed a significant increase in fasting insulin level in the Gestation group compared with Control. Such changes were contrary to the changes of GnRH level in the pancreas. This may imply that GnRH influences hormones secretion in the pancreas by autocrine and paracrine effects on islet cells.

The correlation between intestinal gonadotropin-releasing hormone (GnRH) and proglucagon in hyperlipidemic rats and Goto-Kakizaki (GK) rats.

Our experiment investigated the mRNA expression of intestinal gonadotropin-releasing hormone (GnRH), proglucagon (PG), and glucagon-like peptide 1 receptor (GLP-1R) in the jejunum, ileum, and colon of rats fed with high-fat diet and Goto-Kakizaki (GK) rats and revealed the physiological role of intestinal GnRH. We found that the GnRH and PG mRNA levels in high-cholesterol (HCh) diet were higher than in the control. However, the GnRH receptor (GnRHR) and GLP-1R mRNA levels did not differ significantly between HCh and control. The GnRH, PG, and GLP-1R mRNA levels in GK rats were lower, respectively, than those in control rats, while the GnRHR levels did not differ significantly between GK rats and control rats. There were no difference in GnRH, PG, GnRHR, and GLP-1R mRNA levels in the ileum and colon tissue between HCh and control rats. The GnRH mRNA levels of GK rats were lower than those in control rats; however, the PG, GLP-1R, and GnRHR levels did not differ significantly between GK and control rats. The GLP-1R mRNA levels of GK rats were lower than those in control rats. The GnRH mRNA expression showed positive correlation with PG mRNA expression in different intestinal sections. The GnRH level in the jejunum showed a significant effect on blood glucose level, while the PG level in the jejunum showed a significant effect on insulin level. This may imply that, compared with the ileum and colon, the jejunum had greater impact on glucose metabolism; furthermore, GnRH might interact with intestinal GLP-1 and GLP-2 through the paracrine and autocrine ways and then regulate glucose metabolism and insulin secretion.

Salidroside protects cardiomyocyte against hypoxia-induced death: a HIF-1alpha-activated and VEGF-mediated pathway.

Cardiomyocyte death (necrosis and apoptosis) plays a critical role in the progress of heart diseases. Salidroside, a phenylpropanoid glycoside isolated from Rhodiola rosea L, has shown cardioprotective effects in vivo. However, whether salidroside has a protective effect against cardiomyocyte death is poorly understood. The present study was aimed to investigate the cardioprotective role of salidroside and the underlying mechanisms in hypoxia-induced cardiomyocyte death. Cardiomyocytes pretreated with or without salidroside for 24 h were exposed to hypoxic condition for 6 h and then cell viability, necrosis, apoptosis, the expressions of HIF-1alpha and VEGF were investigated. Pretreatment with salidroside markedly attenuated hypoxia-induced cell viability loss, cell necrosis and apoptosis in a dose-dependent manner. Mechanistically, pretreatment with salidroside up-regulated the HIF-1alpha protein expression and induced its translocation. Moreover, the level of VEGF, a downstream target of HIF, was significantly increased in parallel with the level of HIF-1alpha following pretreatment with salidroside. However, 2-methoxyestradiol (2-ME2), a HIF-1alpha inhibitor, attenuated the protection of salidroside and blocked the increase of HIF-1alpha and VEGF. These data indicated that salidroside has protective effect against hypoxia-induced cardiomyocytes necrosis and apoptosis by increasing HIF-1alpha expression and subsequently up-regulating VEGF levels.

Neuroprotective effects of (-)-epigallocatechin-3-gallate (EGCG) on paraquat-induced apoptosis in PC12 cells.

Green tea, owing to its beneficial effect on health, is becoming more and more popular worldwide. (-)-Epigallocatechin-3-gallate (EGCG), the main ingredient of green tea polyphenols, is a known protective effect on injured neurons in neurodegenerative disease, such as Alzheimer's disease and Parkinson's disease. Paraquat (PQ) is a widely used herbicide that possesses a similar structure to MPP(+) and is toxic to mesencephalic dopaminergic neurons. In the present study, PQ-injured PC12 cells were chosen as an in vitro cell model of Parkinson's disease and the neuroprotective effects of EGCG were investigated. The results showed that EGCG attenuated apoptosis of PC12 cells induced by PQ. The possible mechanism may be associated with maintaining mitochondrial membrane potential, inhibiting caspase-3 activity and downregulating the expression of pro-apoptotic protein Smac in cytosol. The present study supports the notion that EGCG could be used as a neuroprotective agent for treatment of neurodegenerative diseases.