Carbon footprint analysis and comprehensive evaluation of municipal wastewater treatment plants under different typical upgrading and reconstruction modes.

The issue of greenhouse gas (GHG) emissions resulting from the upgrading and reconstruction of municipal wastewater treatment plants (MWWTPs) along with improved water quality is receiving attention and research. There is an urgent need to explore the impact of upgrading and reconstruction on carbon footprint (CF) in order to address concerns that the upgrading and reconstruction will increase GHG emissions while improving water quality. Here we accounted for the CF of five MWWTPs in Zhejiang Province, China, before and after three different upgrading and reconstruction models - "Improving quality and efficiency" ("Mode I"), "Upgrading and renovation" ("Mode U") and "Improving quality and efficiency plus Upgrading and renovation" ("Mode I plus U"). The upgrading and reconstruction was found to not necessarily result in more GHG emissions. In contrast, the "Mode I" had a more significant advantage in terms of CF reduction (1.82-12.6 % reduction in CF). Overall, the ratio of indirect emissions to direct emissions (indirect emissions/direct emissions) and the amount of GHG emitted per unit of pollutant removed (CFCOD、CFTN、CFTP) decreased, while both the carbon and energy neutral rates increased significantly (up to 33.29 % and 79.36 % respectively) after all three upgrading and reconstruction modes. In addition, the wastewater treatment efficiency and capacity are the main factors that affect the level of carbon emission. The results of this study can provide a calculation model that can be used for other similar MWWTPs during the upgrading and reconstruction processes. More importantly, it can provide a new research perspective as well as valuable information to revisit the impact of upgrading and reconstruction in MWWTPs on GHG emissions.

Evaluation of the coagulation properties of magnesium hydroxide for removal combined contamination of reactive dyes and microfibers.

Microfibers are a new type of pollutants that are widely distributed in water bodies. And the simultaneous removal of pollutants in water is popular research in the field of water treatment. In this study, magnesium hydroxide was used as coagulant to investigate the performance and mechanism of coagulation and removal of dyes (reactive orange) and microfibers (MFs). The presence of dyestuff in the composite system promoted the removal of microfibers, and the maximum removal efficiency of both could reach 95.55% and 95.35%. The coagulation mechanism was explored by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and zeta potential. The removal of reactive orange and microfibers relied on electrical neutralization, sweep flocculation, and adsorption mechanisms. Turbidity can enhance the removal efficiency of both. Boosting the rotational speed can increase the removal efficiency of microfibers. This study provides an important theoretical support for an in-depth understanding of the characteristics and mechanisms of coagulation for the removal of complex pollutants from printing and dyeing wastewater.

Coagulation properties of magnetic magnesium hydroxide for removal of microplastics in the presence of kaolin and humic acid.

Microplastics (MPs) is one of the most concerned emerging pollutants in recent years. Its widespread distribution has been shown to have potentially adverse effects on human health and ecosystems. Therefore, in this study, magnetic magnesium hydroxide coagulant (MMHC) was prepared by adding Fe3O4 magnetic micron particles in the Mg(OH)2 generation process, and it was used with PAM, a polymer flocculant, to remove polyethylene microplastics (≤270 µm) from water by coagulation. The removal efficiency of microplastics by MMHC reached 87.1%, which was 14.7% higher than that of traditional magnesium hydroxide coagulant (MHC). However, the Zeta potential of MMHC was lower than that of MHC, only 17.3 mV. In addition, the surface morphology of MMHC showed bubble-like clusters. The effect of PAM adding time on the microplastic removal efficiency was investigated. The best adding time of non-ionic PAM was 15s before the slow mixing started. The removal efficiency of organic matter and suspended particles in water by MMHC was determined by turbidity, ultraviolet spectrophotometry and three-dimensional fluorescence. The maximum removal efficiency was 98.5% and 93.3%, respectively. With the increase of the concentration of humic acid and kaolin in water, the removal efficiency of microplastics was basically not affected. MMHC can be reused after recycle, but it was found that the electrical neutralization mechanism was affected due to the transformation of its Zeta potential, and the adsorption effect of humic acid and kaolin particles in water became worse, the removal efficiency of microplastics, turbidity and UV254 decreased to 20.2%, 17.5% and 30%, respectively.

Performance enhancement and population structure of denitrifying phosphorus removal system over redox mediator at low temperature.

The development of denitrifying polyphosphate accumulating organisms (DPAOs) presents a strategy to carbon competition between denitrifying bacteria and phosphorus removing bacteria. However, low temperature inhibits the rate of enzyme-catalyzed and substrate diffusion during denitrifying phosphorus removal (DPR). Therefore, the present study assessed the addition of NQS (100 µmol/L) for enhancing the removal of TP and TN in DPR reactors operated at alternating anaerobic and anoxic phases and different influent phosphate concentrations. The results showed that the removal efficiency of TP and TN in NQS-DPR system at 10 °C were 99.9% and 42.0%, respectively, which were 2.1 and 2.0 times higher than that of DPR system. Adding NQS significantly alleviated the increase of pH under anoxic condition and decreased the ORP value of the reactor, which in turn enhanced the PHAs accumulation process. The determination of functional genes (nirK, narG and phoD) showed that Dechloromonas, Lentimicrobium, and Terrimonas were the dominant functional bacteria in NQS-DPR system at 10 °C with the relative abundance of 3.09%, 2.99% and 2.28%, respectively. This study can provide valuable information for the effects of the addition of the redox mediator on denitrifying phosphorus removal technology.

Hydrochemistry characteristics of groundwater with the influence of spatial variability and water flow in Hetao Irrigation District, China.

Groundwater is an important resource of water in arid and semi-arid agricultural regions. Thus, identification of hydrogeochemical characters and the influence of geospatial variability and flow pooling are of significance on groundwater resources management and making irrigation decisions in salinized areas. The study specifically focused on the Hetao Irrigation District located in the semi-arid region of northern China. A total of 85 groundwater samples (42 from the upstream Shenwu Irrigation Area (SWIA), 43 from the downstream Wulate Irrigation Area (WLTIA)) were collected, and 15 water quality indexes were analyzed. Methods including mathematical statistics, Piper diagram, Gibbs model, forward succession model, and ionic rations were used to analyze the hydrochemical characteristics and evolution mechanisms, RSBC, PS, SAR, WQI were selected to evaluate water quality and irrigation suitability from the perspective of salt and alkali damage. Results showed that the groundwater of the study area is weakly alkaline, SWIA is mainly fresh water (47.62%), WLTIA is mainly brackish water (65.12%), and the hydrochemistry of the groundwater consists of Cl-Na type and Cl·SO-Ca·Mg. The solute content of downstream (WLTIA) is higher than that of upstream (SWIA), Na+ and Cl- have obvious advantages in WLTIA, and they are the main contribution indicators of groundwater TDS in the study area. The groundwater is subjected to the ongoing influence of rock weathering, ions exchange, and evaporate crystallization Na+ mainly originates from the dissolution of evaporate salt rock and silicate rock, and Ca2+ from the dissolution of gypsum and carbonate. The order of contribution of different rocks is evaporation rock > silicate rock > carbonate rock. Based on the classifications of sodium absorption ratio (SAR), residual sodium bicarbonate (RSBC), and potential salinity (PS), most of the groundwater samples are unsuitable for irrigating, and the groundwater quality of the SWIA is better than that of the WLTIA.

[Temporal and Spatial Variation Characteristics and Driving Factors of Nitrogen of Shallow Groundwater in Hetao Irrigation District].

As an important food production area in the north of China, the Hetao plain is extremely vulnerable to nitrate pollution caused by agricultural production activities and additional factors. Thus, it is of great significance for the environmental protection and rational use of groundwater to detect the current situation of groundwater nitrate pollution, temporal and spatial evolution characteristics, and main influencing factors in the Hetao irrigation district. We selected the Wualte irrigation area as the study area, and the characteristics of temporal and spatial changes in groundwater nitrate concentration and the main influencing factors in this area were explored. We used statistical analysis to analyze the nitrogen content of groundwater in the study area, and the Piper three-line diagram was used to explore the characteristics of chemical composition and evolution; furthermore, we used ion ratio and correlation analysis methods to explore the source of NO3--N in groundwater. The results showed that NO3--N was the main existing form of nitrogen in the Wulate irrigation area, and its concentration varied from 0.01 to 60.00 mg·L-1, with an exceeding standard rate of 10.50%. In terms of time, the characteristic of time change was that the NO3--N concentration in August of groundwater was the highest (average 6.61 mg·L-1), followed by that in October (6.22 mg·L-1) and November (6.25 mg·L-1), and that in March (average value of 1.77 mg·L-1) was the lowest. With the influence of rainfall and irrigation, the NO3--N in the soil was infiltrated into the groundwater, showing the characteristic that wet season and concentrated irrigation periods were higher than those in other periods. Spatially, it appeared as southwest (8.87 mg·L-1)>northwest (4.25 mg·L-1)>east (0.89 mg·L-1), mainly due to the original geological conditions, land use, and domestic waste stacking. In addition, the concentration of NO3--N of groundwater in the study area was closely related to the depth of groundwater and redox conditions but was relatively less affected by the concentration of water chemical ions. Therefore, identifying the temporal and spatial distribution characteristics and main sources of groundwater nitrogen pollution can provide a scientific basis for scientific fertilization, groundwater nitrate pollution control, and water safety.

Downregulated circular RNA hsa_circ_0005797 inhibits endometrial cancer by modulating microRNA-298/Catenin delta 1 signaling.

Abnormal expression of circular RNA (circRNA) expression has been implicated in endometrial cancer (EC) progression. Thus, investigation of the mechanism of hsa_circ_0005797 during EC etiology may provide new insight into the treatment of EC. In the present study, we found that hsa_circ_0005797 expression was significantly increased in EC biological samples and cell lines, whereas its downregulation inhibited in vitro tumor cells proliferation and invasion phenotypes and suppressed tumor formation in nude mice. In mechanism, we characterized hsa_circ_0005797 as an miR-298 sponge, with CTNND1 identified as a target of miR-298. Our rescue assay data further revealed that hsa_circ_0005797 silencing inhibited EC cells proliferation and invasion via miR-298/CTNND1 signaling. In conclusion, our study confirmed hsa_circ_0005797 is a poor prognostic factor for EC and modulates EC phenotypes by regulating the hsa_circ_000579/miR-298/CTNND1 signaling, which provides potential treatment targets for EC.

Startup and performance of a novel single-stage partial nitritation/anammox system for reject water treatment.

A novel internal circulation contact oxidation membrane bioreactor (ICCOMBR) was constructed to investigate a three steps startup strategy of single-stage partial nitritation-anammox (SPNA) system. A stable nitrite accumulation rate (NAR) of 86.60% was achieved with NH4+-N over 250 mg/L in nitritation process. The partial nitritation process could be effectively achieved by reducing the aeration rate (AR) by about 50% in the nitritation process, with an effluent NO2--N/NH4+-N ratio of 1.15 ± 0.04. The SPNA system was started up in 27 days following the inoculated anammox granular sludge. A total nitrogen removal efficiencies of 82% was achieved at a NLR of 0.60 gN/L/d and dissolved oxygen (DO) concentration below 0.55 mg/L. Anammox function genus (Ca.Kuenenia and Ca. Anammoximicrobium) abundance accounted for 20.77% in the biofilm, which is approximately equal to 22.2% in the suspended sludge. Nitrosomon as the dominant AOB genera, was detected in the biofilm (6.5%) and suspended sludge (13.3%).

Alteration of denitrifying microbial communities by redox mediators available at low temperature.

Four sequential batch reactors (SBRs) containing synthetic sewage for denitrification were investigated in this study. Three of them had added one of the three redox mediators, which were anthraquinone-1,5-disulfonate (AQDS), 1,2-naphthoquinone-4-sulfonate (NQS), and 2-hydroxy-1,4-naphthoquinone (LAW), operated at 20 °C and 10 °C, and an additional one to serve as the control. Results showed that 10 °C inhibited denitrification to a considerable extent, but the addition of mediators increased the denitrification rate and efficiency. The total nitrogen removal efficiency increased in the presence of three different redox mediators (100 µmol/L), among which LAW express the best accelerating effectiveness at normal temperature and NQS at low temperature. This may be due to the growth of microorganisms, whose community compositions changed considerably when the different redox mediators were added. Therefore, Illumina MiSeq sequencing was used to identify the different microbial communities. Thauera was dominant at 10 °C (25.60%). Furthermore, the addition of mediators greatly promoted Thauera growth (31.11%-42.41%), especially LAW (42.41%). At 20 °C, Candidatus Competibacter (8.31%-9.59%) and Denitratisoma (6.33%-7.39%) were dominant. Thauera and Denitratisoma are denitrifiers. These results could improve understanding of the sewage biological process at low temperature.

Hsa_circ_0002577 promotes endometrial carcinoma progression via regulating miR-197/CTNND1 axis and activating Wnt/ß-catenin pathway.

Circular RNA (circRNA) is involved in a wide range of life processes including tumorigenesis. However, the molecular mechanisms of circRNA in endometrial carcinoma (EC) carcinogenesis remain unclear. In the present study, we aimed to investigate the potential modulation of hsa_circ_0002577 on EC progression. Here, we showed that hsa_circ_0002577 expression was significantly upregulated in EC tissues, and high hsa_circ_0002577 expression was associated with advanced FIGO stage, lymph node metastasis, and poor overall survival rate of EC patients. In function assays, we demonstrated that hsa_circ_0002577 knockdown significantly reduced EC cells proliferation, migration, invasion ability in vitro and decreased tumor growth in vivo. In mechanism study, we revealed that hsa_circ_0002577 might act as a sponge for miR-197, and CTNND1 was revealed to be a target gene of miR-197. In addition, we revealed that the oncogenic effects of hsa_circ_0002577 were attributed to the regulation of miR-197/CTNND1/Wnt/ß-catenin axis. Taken together, we indicated that hsa_circ_0002577 could play critical functions by hsa_circ_0002577/miR-197/CTNND1/Wnt/ß-catenin signaling pathway, which served as a novel therapeutic application for EC treatment.

Occurrence, genotyping, and health risk of Cryptosporidium and Giardia in recreational lakes in Tianjin, China.

Cryptosporidium and Giardia are critical parasites in the etiology of diarrhea worldwide, and often cause waterborne outbreaks. The presence of Cryptosporidium and Giardia in recreational lakes was investigated with molecular characterization, and a comprehensive quantitative microbial risk assessment (QMRA) of protozoan infections was performed, considering multiple exposure pathways, differences in age, sex, and disease severity, and the genotypes of the protozoa. Forty-three (82.7%) and 51 (98.1%) water samples were positive for Cryptosporidium oocysts and Giardia cysts, respectively, with average counts of 3.65 oocysts/10 L and 12.58 cysts/10 L, respectively. Six Cryptosporidium species and three Giardia lamblia assemblages were confirmed with molecular analyses. The protozoan concentration was significantly associated with water turbidity, but not with the total coliform numbers. Swimming in the lakes entailed the highest incidence risk of 5.72 × 10-4 per person per year (pppy) (95% confidence interval (CI): 0.03-43.33 × 10-4) for Cryptosporidium and 4.04 × 10-4 pppy (95% CI: 0.01-32.66 × 10-4) for Giardia, whereas wading entailed the lowest risk (2.20 × 10-4 and 1.70 × 10-4 pppy, respectively). The annual burdens attributable to recreational-water-associated cryptosporidiosis and giardiasis were 3.44 (95% CI: 0.04-23.51) and 1.81 (95% CI: 0.01-12.96) disability-adjusted life years per 1,000,000 individuals per year, respectively. Children were more likely to have an individual disease burden than adults, and males were more likely than females. Sensitivity analysis highlighted the great importance of controlling the proportion of exposed individuals and reducing the frequency of exposure. The methodology and results of this study will allow us to better evaluate and reduce the burden of Cryptosporidium and/or Giardia infections associated with recreational water use in China and other countries.

Improved sludge dewaterability and hydrolysis performance after pretreatment with Fenton's reagent.

The dewaterability of excess sludge significantly improved upon pretreatment with Fenton's reagent in this study. After 0.9 g/L of Fe2+ and 5.0 g/L of H2O2 were added to the sludge, and reacted for 2 h at pH = 4, the specific resistance to filtration (SRF) of the excess sludge decreased from an initial value of 29.74 × 1012 m/kg to 6.49 × 1012 m/kg. The factors that affected this improvement in sludge dewaterability as evaluated by SRF reduction showed the following order: H2O2 > pH > Fe2+ > reaction time. Furthermore, the hydrolysis performance of the sludge under the optimal reaction conditions was investigated. The results indicated that the concentration of soluble chemical oxygen demand in the supernatant increased almost 14 times compared to raw sludge, and the contents of soluble protein and soluble polysaccharide were more than 8 and 17 times higher, respectively, than for the untreated situation. However, the amounts of ammonia nitrogen (NH4+-N) and phosphate (PO43--P) released from the sludge showed different trends: NH4+-N increased by 200%, while PO43--P decreased by 82%. The production of volatile fatty acids (VFAs) from the treated sludge showed that total VFAs increased by 66%, and iso-butylacetic acid was the dominant product among the total VFAs.

The Impact of Peroxisome Proliferator-Activated Receptor Gamma and Its Interaction with Abdominal Obesity on Diabetic Nephropathy in Chinese Han.

BACKGROUND: Several studies have focused on the association between peroxisome proliferators-activated receptor gamma (PPARG) polymorphism and diabetic nephropathy (DN); however, the results of these studies were inconsistent, and until now, no population-based study has focused on the impact of PPARG gene-abdominal obesity interaction on DN risk. The aim of this study was to investigate the impact of PPARG polymorphisms and its interaction with abdominal obesity on DN risk in the Chinese Han population. METHODS: A total of 848 patients with type 2 diabetes mellitus, including 420 DN patients and 428 controls were recruited. Generalized multifactor dimensionality reduction (GMDR) and logistic regression model were used to examine the association and interaction between single nucleotide polymorphism and abdominal obesity on DN; OR and 95% CI were calculated. RESULTS: We found a significant association between CG or GG in rs1805192 and increased DN risk. DN risk was higher in the carriers of CG or GG genotype of rs1805192 than those with CC genotype; OR (95% CI) was 1.31 (1.11-1.58). GMDR analysis suggested a significant 2-locus model (p = 0.0107) involving rs1805192 and abdominal obesity, indicating a potential gene-environment interaction between rs1805192 and abdominal obesity. Overall, the 2-locus models had a cross-validation consistency of 10 of 10, and the testing accuracy of 62.17%. CONCLUSIONS: Our results support an important association between rs1805192 minor allele (G allele) of PPARG and increased DN risk; the interaction analysis showed a combined effect of interaction between rs1805192 and abdominal obesity on DN risk. The results obtained from this study are meaningful for studies on individualized PPARG agonist in treating DN for different persons, such as abdominal obese or non-abdominal obese subject.

Upregulation of microRNA­337 promotes the proliferation of endometrial carcinoma cells via targeting PTEN.

Endometrial carcinoma (EC) is a common malignancy in females. MicroRNAs (miRs) are a class of non­coding RNA that regulate a wide variety of cellular processes, and are important in the development of multiple types of malignancy. In the present study, cancerous and adjacent non­cancerous normal tissue samples were collected from 24 patients diagnosed with EC. Reverse transcription quantitative polymerase chain reaction was performed on the tissue samples to determine the expression levels of six candidate miRs. These miRs have been previously reported to be differentially expressed in EC; however, the present study observed that only miR­337 was differentially expressed. In addition, the current study identified phosphatase and tensin homolog (PTEN) as a target of miR­337 using computational analysis and a luciferase assay. EC cells transfected with miR­337 mimics and anti­PTEN small interfering RNA demonstrated significantly decreased expression of PTEN, markedly increased proliferation and inhibition of cell apoptosis. The results indicate that miR­337 is oncogenic in EC cells, as it suppresses PTEN expression. This may facilitate the development of miR­based prevention or treatment strategies for EC.

TNFα up-regulates COX-2 in chronic progressive nephropathy through nuclear accumulation of RelB and NF-κB2.

OBJECTIVE: The pathogenesis of progressive nephropathies involves inflammatory factors. The inhibition of cyclooxygenase-2 (COX-2) can limit renal damage and inflammation. However, the mechanism of up-regulation of COX-2 in nephropathy is poorly defined. MATERIALS AND METHODS: Here we found that tumor necrosis factor alpha (TNFα) was involved in expression of COX-2 in normal rat kidney (NRK) cell line. RESULTS: TNFα stimulated COX-2 production in a time-dependent manner in NRK cells by inducing nuclear accumulation of RelB and nuclear factor kappa B2 (NF-κB2) and their association with COX-2 gene promoter. Depletion of IκB-inducing kinase alpha, a positive regulator of activation of p100 processing to active p52, attenuated TNFα-induced COX-2 production. Furthermore, TNFα induced COX-2 production and nuclear import in anti-thymocyte serum (ATS) nephropathy. DISCUSSION AND CONCLUSION: These data suggest that TNFα-RelB/p52 pathway may be involved in the early stages of renal damage, in part by stimulating COX-2 and inflammatory responses.

Granular ferric hydroxide adsorbent for phosphate removal: demonstration preparation and field study.

Ferric hydroxide (FHO), which has high phosphate adsorption capacity, was prepared by precipitation at industrial scale and then fabricated via the drum granulation method with cross-linked poly(vinyl alcohol) as the binder. The optimum binder/FHO powder ratio was 0.6 for producing a granular adsorbent with a high phosphate adsorption capacity and stability. The Langmuir maximum adsorption capacities of powder and granular FHOs were 74.07 mg g⁻¹ and 56.18 mg g(-1) at pH 7.0 ± 0.2, respectively, which were higher than those of other reported phosphate adsorbents under neutral or acidic conditions. Phosphate-loaded granular FHO could be regenerated by NaOH solution. Columns containing the granular FHO were used for phosphate removal from ozonated secondary effluents of a municipal wastewater treatment plant at space velocity (SV) of 2 and 5 h⁻¹. During more than 2 months' operation, the average removal percentage of PO(4)(3-) was more than 90% and the turbidity and concentration of CODMn in the effluents were lower than in the influents. In addition, energy dispersive X-ray results suggested that active sites inside the granular FHO were available for phosphate removal. The results demonstrated that granular FHO can be applied as an assist technology for phosphate removal from secondary effluents.

Risk assessment of Giardia from a full scale MBR sewage treatment plant caused by membrane integrity failure.

Membrane bioreactors (MBR) are highly efficient at intercepting particles and microbes and have become an important technology for wastewater reclamation. However, many pathogens can accumulate in activated sludge due to the long residence time usually adopted in MBR, and thus may pose health risks when membrane integrity problems occur. This study presents data from a survey on the occurrence of water-borne Giardia pathogens in reclaimed water from a full-scale wastewater treatment plant with MBR experiencing membrane integrity failure, and assessed the associated risk for green space irrigation. Due to membrane integrity failure, the MBR effluent turbidity varied between 0.23 and 1.90 NTU over a period of eight months. Though this turbidity level still met reclaimed water quality standards (≤5 NTU), Giardia were detected at concentrations of 0.3 to 95 cysts/10 L, with a close correlation between effluent turbidity and Giardia concentration. All ß-giardin gene sequences of Giardia in the WWTP influents were genotyped as Assemblages A and B, both of which are known to infect humans. An exponential dose-response model was applied to assess the risk of infection by Giardia. The risk in the MBR effluent with chlorination was 9.83×10(-3), higher than the acceptable annual risk of 1.0×10(-4). This study suggested that membrane integrity is very important for keeping a low pathogen level, and multiple barriers are needed to ensure the biological safety of MBR effluent.

Fish larval deformity caused by aldehydes and unknown byproducts in ozonated effluents from municipal wastewater treatment systems.

Ozonated secondary effluents (SEs) from municipal wastewater treatment plants (MWTPs) have been found to cause developmental retardation of fish embryos. This study explored the potential cause of the embryo toxicity formed in ozonated SEs by exposing Japanese medaka (Oryzias latipes) (d-rR) embryos to ozonated SE from a MWTP in Tianjin, China. The increase of ozone dose from 0.26 to 0.96 mg O3/mg DOC0 (consumed ozone per initial DOC), which produced total aldehyde (mixture of formaldehyde, acetaldehyde, propionaldehyde, and glyoxal) from 41.5 to 114.7 µg/L, resulted in an increase in the percentage of deformed larvae from 2.2% to 24.1%. Increases in larval deformity and embryo mortality were also observed in ozonated SEs from other MWTPs. The exposure experiment using the mixture aldehyde solution showed that the production of aldehydes could explain approximately 13.6% of larval deformity caused by ozonation of SEs. Pilot experimental results in Tianjin and Beijing, China showed that biofiltration as a post-treatment technology was effective in removing the aldehydes as well as reducing embryo toxicity caused by ozonation.

Effects of long-term treatment with quercetin on cognition and mitochondrial function in a mouse model of Alzheimer's disease.

Amyloid-ß (Aß)-induced mitochondrial dysfunction has been recognized as a prominent, early event in Alzheimer's disease (AD). Therefore, therapeutics targeted to improve mitochondrial function could be beneficial. Quercetin, a bioflavanoid, has been reported to have potent neuro-protective effects, but its preventive effects on Aß-induced mitochondrial dysfunction and cognitive impairment have not been well characterised. Three-month-old APPswe/PS1dE9 transgenic mice were randomly assigned to a vehicle group, two quercetin (either 20 or 40 mg kg(-1) day(-1)) groups, or an Aricept (2 mg kg(-1) day(-1)) group. After 16 weeks of treatment, we observed beneficial effects of quercetin (40 mg kg(-1) day(-1)), including lessening learning and memory deficits, reducing scattered senile plaques, and ameliorating mitochondrial dysfunction, as evidenced by restoration of mitochondrial membrane potential, reactive oxygen species and ATP levels in mitochondria isolated from the hippocampus compared to control. Furthermore, the AMP-activated protein kinase (AMPK) activity significantly increased in the quercetin-treated (40 mg kg(-1) day(-1)) group. These findings suggest that a reduction in plaque burden and mitochondrial dysfunction through the activation of AMPK may be one of the mechanisms by which quercetin improves cognitive functioning in the APPswe/PS1dE9 transgenic mouse model of AD.