Enhancement of electron transfer via magnetite in nitrite-dependent anaerobic methane oxidation system.

Nitrite-dependent anaerobic methane oxidation (n-DAMO) is a novel denitrification process that simultaneously further removes and utilizes methane from anaerobic effluent from wastewater treatment plants. However, the metabolic activity of n-DAMO bacteria is relative low for practical application. In this study, conductive magnetite was added into lab-scale sequencing batch reactor inoculated with n-DAMO bacteria to study the influence on n-DAMO process. With magnetite amendment, the nitrogen removal rate could reach 34.9 mg N·L-1d-1, nearly 2.5 times more than that of control group. Magnetite significantly facilitated the interspecies electron transfer and built electrically connected community with high capacitance. Enzymatic activities of electron transport chain were significantly elevated. Functional gene expression and enzyme activities associated with nitrogen and methane metabolism had been highly up-regulated. These results not only propose a useful strategy in n-DAMO application but also provide insights into the stimulating mechanism of magnetite in n-DAMO process.

Enhancement of nitrogen removal in coupling Anammox and DAMO via Fe-modified granular activated carbon.

Anaerobic ammonium oxidation (Anammox) coupled with Denitrifying anaerobic methane oxidation (DAMO) is an attractive technology to simultaneously remove nitrogen and mitigate methane emissions from wastewater. However, its nitrogen removal rate is usually limited due to the low methane mass transfer efficiency, low metabolic activity and slow growth rate of functional microorganisms. In this study, GAC and Fe-modified GAC (Fe-GAC) were added into Anammox-DAMO process to investigate their effects on nitrogen removal rates and then reveal the mechanism. The results showed that after 80-day experiments, the total nitrogen removal rate was slightly improved in the presence of GAC (3.94 mg L-1·d-1), while it reached high as 16.66 mg L-1·d-1 in the presence of Fe-GAC, which was ca.17 times that of non-amended control group (0.96 mg L-1·d-1). The addition of Fe-GAC stimulated the secretion of extracellular polymeric substance (EPS), improved the electron transfer capability and promoted the production of Cytochrome C. Besides, the key functional enzyme activities (HZS, HDH and NAR) were highest in the Fe-GAC group, which were approximately 1.06-1.56 times higher than those of GAC-amended and blank control groups. Microbial community analysis showed that the abundance of the DAMO archaea (Candidatus Methanoperedens) and Anammox bacteria (Candidatus Brocadia) were remarkably increased with the addition of Fe-GAC. Functional genes associated with nitrogen removal and methane oxidation in Fe-GAC system were up-regulated. This study provides a promising strategy for achieving high rate of nitrogen removal upon Anammox-DAMO process.

Enhancement of nitrate-dependent anaerobic methane oxidation via granular activated carbon.

Denitrifying anaerobic methane oxidation (DAMO) is a bioprocess utilizing methane as the electron source to remove nitrate or nitrite, but denitrification rate especially for nitrate-dependent DAMO is usually limited due to the low methane mass transfer efficiency. In this research, granular active carbon (GAC) was added to enhance the nitrate-dependent DAMO process. The results showed that the maximum nitrate removal rate of GAC assisted DAMO system reached as high as 61.17 mg L-1 d-1, 8 times higher than that of non-amended control SBR. The porous structure of GAC can not only adsorb methane, but also keep the internal DAMO archaea from being washed out, and thus benefits for DAMO archaea enrichment. The relative abundance of DAMO archaea accounted for 96.3% in GAC-SBR, which was significantly higher than that of non-amended control SBR system (29.9%). Furthermore, GAC amendment up-regulated metabolic status of denitrification and methane oxidation based on gene sequence composition. The absolute abundances of function genes (NC10 pmoA and ANME mcrA) in GAC-SBR were almost 20 times higher than that of non-amended control SBR. This study provides a novel technique to stimulate the nitrate-dependent DAMO process.

Enhancement of denitrifying anaerobic methane oxidation via applied electric potential.

In this study, single-chamber three-electrode electrochemical sequencing batch reactor (ESBR) was set up to investigate the impact of applying potential on denitrifying anaerobic methane oxidation (DAMO) process. When the applied potential was +0.8 V, the conversion rate of nitrite to nitrogen was superior to those of other potentials. With the optimal potential of +0.8 V for 60 days, the nitrite removal rate of ESBR could reach 3.34 ± 0.28 mg N/L/d, which was 4.5 times more than that of the non-current control (0.74 ± 0.16 mg N/L/d). The DAMO functional bacteria Candidatus Methylomirabilis exhibited noticeable enrichment under applying potential, and its functional gene of pmoA was significantly expressed. Through untargeted LC-MS metabolomics analysis, applied potential was shown to affect the regulation of prior metabolites including spermidine, spermine and glycerophosphocholine that were related to the metabolic pathways of glycerophospholipid metabolism and arginine and proline metabolism, which had positive effects on DAMO process. These results show that applying electric potential could be a useful strategy in DAMO process used for methane and nitrogen removal.

Characterization of complexes of PF4 and heparins by size-exclusion chromatography coupled with multi-angle light scattering detector.

Heparin-induced thrombocytopenia (HIT) is an immune complication of heparin therapy. Antibodies binding to complexes of platelet factor 4 (PF4) and heparin is the trigger of HIT. A method using size exclusion chromatography with multi-angle laser light scattering detector (SEC-MALS) was developed in this work. The soluble ultra-large complex (ULC) was separated from the small complex (SC) and their molecular weights (MWs) were firstly measured. The complexes of PF4 and three heparins with different MW, including unfractionated heparin (UFH), dalteparin (Daltep) and enoxaparin (Eno) were characterized using this method. The contents and the sizes of ULC increased gradually when heparins were added to PF4 to certain amounts. While, they reduced after more heparins were added. It is the first time to measure the MWs of the biggest ULC of PF4-heparins as millions of Dalton. at the proper ratios of PF4 to heparin (PHR). Meanwhile, those mixtures at those certain PHRs induced the higher expression of CD83 and CD14 markers on dendritic cells (DCs) suggesting that they had stronger immunogenicity and is critical for HIT.

An HPLC method for microanalysis and pharmacokinetics of marine sulfated polysaccharide PSS-loaded poly lactic-co-glycolic acid (PLGA) nanoparticles in rat plasma.

This study was aimed at developing a sensitive and selective HPLC method with postcolumn fluorescence derivatization for the detection of propylene glycol alginate sodium sulfate (PSS) in rat plasma. Plasma samples were prepared by a simple and fast ultrafiltration method. PSS was extracted from rat plasma with D-glucuronic acid as internal standard. Isocratic chromatographic separation was performed on a TSKgel G2500 PWxL column with the mobile phase of 0.1 M sodium sulfate at a flow rate of 0.5 mL/min. Analyte detection was achieved by fluorescence detection (FLD) at 250 nm (excitation) and 435 nm (emission) using guanidine hydrochloride as postcolumn derivatizing reagent in an alkaline medium at 120 °C. The calibration curve was linear over a concentration range of 1-500 µg/mL, and the lower limit of detection (LLOD) was found to be 250 ng/mL. This validated method was applied successfully to the pharmacokinetic study of PSS and PSS-loaded poly lactic-co-glycolic acid (PLGA) nanoparticles (PSS-NP) in rat plasma after a single intravenous (PSS only) and oral administration (PSS and PSS-NP). Significant differences in the main pharmacokinetic parameters of PSS and PSS-NP were observed. The relative bioavailability of PSS-NP was 190.10% compared with PSS which shows that PSS-NP can improve oral bioavailability.

Role of MAIT cells in gastrointestinal tract bacterial infections in humans: More than a gut feeling.

Mucosa-associated invariant T (MAIT) cells are the largest population of unconventional T cells in humans. These antimicrobial T cells are poised with rapid effector responses following recognition of the cognate riboflavin (vitamin B2)-like metabolite antigens derived from microbial riboflavin biosynthetic pathway. Presentation of this unique class of small molecule metabolite antigens is mediated by the highly evolutionarily conserved major histocompatibility complex class I-related protein. In humans, MAIT cells are widely found along the upper and lower gastrointestinal tracts owing to their high expression of chemokine receptors and homing molecules directing them to these tissue sites. In this review, we discuss recent findings regarding the roles MAIT cells play in various gastrointestinal bacterial infections, and how their roles appear to differ depending on the etiological agents and the anatomical location. We further discuss the potential mechanisms by which MAIT cells contribute to pathogen control, orchestrate adaptive immunity, as well as their potential contribution to inflammation and tissue damage during gastrointestinal bacterial infections, and the ensuing tissue repair following resolution. Finally, we propose and discuss the use of the emerging three-dimensional organoid technology to test different hypotheses regarding the role of MAIT cells in gastrointestinal bacterial infections, inflammation, and immunity.

The reason and mechanism of propylene glycol alginate sodium sulfate (PSS) mediated allergic side effect.

Propylene glycol alginate sodium sulfate (PSS) is a heparinoid polysaccharide drug used in clinic for >30 years in China. But its allergy events happened from time to time and should not be ignored. Here, ammonium salt in PSS (PSS-NH4+), PSS fractions with high Mw (PSS-H-Mw) and low mannuronic acid (M) to guluronic acid (G) ratio (PSS-L-M/G) were found to induce allergic response by the structure-activity and impurity-activity relationships in vitro. Furthermore, we confirmed the reason and elucidated the mechanism accounted for allergic side effect of PSS in vivo. It was found that high IgE levels in PSS-NH4+ and PSS-H-Mw groups upregulate the cascade expression of Lyn-Syk-Akt or Erk and second messenger Ca2+, which accelerated mast cells (MCs) degranulation to release histamine, LTB4, TPS, and finally induced lung tissue injury. PSS-L-M/G caused a mild allergic symptom because it only enhanced the expression of p-Lyn and histamine release. In brief, PSS-NH4+ and PSS-H-Mw were main reasons to result in allergic response. Our results suggested that it is very necessary to control the range of Mw and the content of impurities (< 1 % ammonium salt) of PSS to guarantee its safety and effectiveness in clinical treatment.

Dynamic modelling of costs and health consequences of school closure during an influenza pandemic.

BACKGROUND: The purpose of this article is to evaluate the cost-effectiveness of school closure during a potential influenza pandemic and to examine the trade-off between costs and health benefits for school closure involving different target groups and different closure durations. METHODS: We developed two models: a dynamic disease model capturing the spread of influenza and an economic model capturing the costs and benefits of school closure. Decisions were based on quality-adjusted life years gained using incremental cost-effectiveness ratios. The disease model is an age-structured SEIR compartmental model based on the population of Oslo. We studied the costs and benefits of school closure by varying the age targets (kindergarten, primary school, secondary school) and closure durations (1-10 weeks), given pandemics with basic reproductive number of 1.5, 2.0 or 2.5. RESULTS: The cost-effectiveness of school closure varies depending on the target group, duration and whether indirect costs are considered. Using a case fatality rate (CFR) of 0.1-0.2% and with current cost-effectiveness threshold for Norway, closing secondary school is the only cost-effective strategy, when indirect costs are included. The most cost-effective strategies would be closing secondary schools for 8 weeks if R0=1.5, 6 weeks if R0=2.0, and 4 weeks if R0= 2.5. For severe pandemics with case fatality rates of 1-2%, similar to the Spanish flu, or when indirect costs are disregarded, the optimal strategy is closing kindergarten, primary and secondary school for extended periods of time. For a pandemic with 2009 H1N1 characteristics (mild severity and low transmissibility), closing schools would not be cost-effective, regardless of the age target of school children. CONCLUSIONS: School closure has moderate impact on the epidemic's scope, but the resulting disruption to society imposes a potentially great cost in terms of lost productivity from parents' work absenteeism.

Comorbidity of cerebellopontine angle meningioma with other primary neoplasms.

BACKGROUND: Meningioma is known to be accompanied by other primary neoplasms, yet has been evaluated less than these. OBJECTIVE: This study investigated comorbidity of cerebellopontine angle (CPA) meningioma with other primary neoplasms. METHODS: Overall 1,085 meningioma cases including 16 meningiomas at the CPA were enrolled for investigating the presence of other primary neoplasms. Another 16 age-, sex-, and size-matched CPA schwannoma were also included for comparison. RESULTS: Of a data-base cohort study of overall 1085 meningioma cases, 165 cases (15%) were associated with other primary neoplasms. In contrast, 8 (50%) of 16 CPA meningioma and one (8%) of 16 CPA schwannoma showed other primary neoplasms. Except for one patient who had oral cancer prior to the diagnosis of CPA meningioma by 4 years, the interval from diagnosis of CPA meningioma to that of other primary neoplasm ranged 0-6 (mean, 3.1 ± 2.5) years. CONCLUSION: Prevalence of comorbidity with other primary neoplasms is significantly higher in CPA meningioma (50%) than overall meningioma (15%) and CPA schwannoma (8%). In addition to follow-up MR imaging to visualize both residual tumor and regional brain environment after treatment of CPA meningioma, long-term systemic screening for other primary neoplasm is also mandatory.

Modeling the cost of influenza: the impact of missing costs of unreported complications and sick leave.

BACKGROUND: Estimating the economic impact of influenza is complicated because the disease may have non-specific symptoms, and many patients with influenza are registered with other diagnoses. Furthermore, in some countries like Norway, employees can be on paid sick leave for a specified number of days without a doctor's certificate ("self-reported sick leave") and these sick leaves are not registered. Both problems result in gaps in the existing literature: costs associated with influenza-related illness and self-reported sick leave are rarely included. The aim of this study was to improve estimates of total influenza-related health-care costs and productivity losses by estimating these missing costs. METHODS: Using Norwegian data, the weekly numbers of influenza-attributable hospital admissions and certified sick leaves registered with other diagnoses were estimated from influenza-like illness surveillance data using quasi-Poisson regression. The number of self-reported sick leaves was estimated using a Monte-Carlo simulation model of illness recovery curves based on the number of certified sick leaves. A probabilistic sensitivity analysis was conducted on the economic outcomes. RESULTS: During the 1998/99 through 2005/06 influenza seasons, the models estimated an annual average of 2700 excess influenza-associated hospitalizations in Norway, of which 16% were registered as influenza, 51% as pneumonia and 33% were registered with other diagnoses. The direct cost of seasonal influenza totaled US$22 million annually, including costs of pharmaceuticals and outpatient services. The annual average number of working days lost was predicted at 793 000, resulting in an estimated productivity loss of US$231 million. Self-reported sick leave accounted for approximately one-third of the total indirect cost. During a pandemic, the total cost could rise to over US$800 million. CONCLUSIONS: Influenza places a considerable burden on patients and society with indirect costs greatly exceeding direct costs. The cost of influenza-attributable complications and the cost of self-reported sick leave represent a considerable part of the economic burden of influenza.

Costs of diarrheal disease and the cost-effectiveness of a rotavirus vaccination program in kyrgyzstan.

INTRODUCTION: We examined the cost-effectiveness of a rotavirus immunization program in Kyrgyzstan, a country eligible for vaccine funding from the GAVI Alliance. METHODS: We estimated the burden of rotavirus disease and its economic consequences by using national and international data. A cost-effectiveness analysis was conducted from government and societal perspectives, along with a range of 1-way sensitivity analyses. RESULTS: Rotavirus-related hospitalizations and outpatient visits cost US$580,864 annually, of which $421,658 (73%) is direct medical costs and $159,206 (27%) is nonmedical and indirect costs. With 95% coverage, vaccination could prevent 75% of rotavirus-related hospitalizations and deaths and 56% of outpatient visits and could avert $386,193 (66%) in total costs annually. The medical break-even price at which averted direct medical costs equal vaccination costs is $0.65/dose; the societal break-even price is $1.14/dose for a 2-dose regimen. At the current GAVI Alliance-subsidized vaccine price of $0.60/course, rotavirus vaccination is cost-saving for the government. Vaccination is cost-effective at a vaccine price $9.41/dose, according to the cost-effectiveness standard set by the 2002 World Health Report. CONCLUSIONS: Addition of rotavirus vaccines to childhood immunization in Kyrgyzstan could substantially reduce disease burden and associated costs. Vaccination would be cost-effective from the national perspective at a vaccine price $9.41 per dose.

Optimization of microwave assisted extraction, chemical characterization and antitumor activities of polysaccharides from porphyra haitanensis.

Microwave assisted extraction (MAE) technology was used to extract polysaccharides from Porphyra Haitanensis (PHP) with water. Polysaccharide yield was used as index to evaluate the extraction process. Effects of ratio of water to raw material (X1), microwave power (X2) and extraction time (X3) on polysaccharide yield were investigated. Based on single factor experiment, MAE process of PHP was optimized using response surface methodology. Chemical characterization of PHP was investigated based on analysis of chemical compositions, monosaccharide and thermal gravimetric. The antitumor activities of PHP in vivo and in vitro were evaluated. The results indicated that the optimal conditions for MAE of PHP were ratio of water to raw material 28.98(mL/g), microwave power 77.84 W and extraction time 14.14 min. MAE was a suitable and efficient technique for PHP extraction compared with traditional hot water extraction. Analysis of chemical characterization showed that PHP contained 75.36 ± 1.48% of total carbohydrates, 24.63 ± 1.69% of uronic acid residue and no proteins with monosaccharides such as rhamnose, arabinose, xylose, mannose, glucose, and galactose in a molar ratio of 10.25:9.38:1:12.45:9.9:11.55. Thermal gravimetric analysis suggested that PHP was relatively stable below 170℃. PHP had obvious effect on inhibiting proliferation, inducing apoptosis of SGC-7901 tumor cells in vitro and antitumor effect on SGC-7901 tumor-bearing mice in vivo. The results suggested that PHP had the potential for clinical use in cancer prevention and treatment.

Purification, chemical characterization and antioxidant activities of a novel polysaccharide from Auricularia polytricha.

A novel water-soluble polysaccharide coded APP3a was isolated and purified from Auricularia polytricha by DEAE-52 cellulose and Sephadex G-200 column chromatography. Chemical characterization of APP3a was investigated based on analysis of high performance liquid chromatography (HPLC), gas chromatography (GC), fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA). Antioxidant activities of APP3a were investigated on the basis of superoxide anion,1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical scavenging activity and reducing power. The results showed that APP3a consisted of arabinose, mannose, glucose and galactose in a molar ratio of 1:1.33:1.06:1.23 with an average molecular weight of 21,242 Da. Thermal gravimetric analysis showed that APP3a was relatively stable below 250 °C. APP3a showed the stronger reducing power and stronger scavenging activity against hydroxyl radicals, superoxide radicals and DPPH radicals in a concentration-dependent manner. These findings suggested that the polysaccharide APP3a could be served as a novel antioxidant in functional food.

The mechanisms of sulfated polysaccharide drug of propylene glycol alginate sodium sulfate (PSS) on bleeding side effect.

Propylene glycol alginate sodium sulfate (PSS), a sulfated polysaccharide derivative, has been used as a heparinoid drug to prevent and treat hyperlipidemia and ischemic cardio-cerebrovascular diseases in China for 30 years. But its bleeding risk should not be overlooked. Here we clarified the reasons and mechanism leading to bleeding side effect of PSS. It was found that PSS fractions with low mannuronic acid (M)/guluronic acid (G) ratio and high molecular weight (Mw) can excessively extend activated partial thromboplastin time (APTT) and thrombin time (TT), over-inhibit the thrombin (FIIa) activity mediated by anti-thrombin III (ATIII) to induce bleeding risk. In addition, the fraction of low M/G ratio can suppress platelet aggregation mediated by adenosine diphosphate (ADP) and induce platelet reduction by improving platelet antibody (PA)-IgA/G in serum and by inhibiting or damaging the bone marrow hematopoietic function. And the fraction of high Mw can restrain the reticulated platelet (RP) production, then reduce mean platelet volume (MPV) and platelet-large cell counts or ratio, and finally decrease platelet amount by inhibiting or damaging the bone marrow hematopoietic function. In brief, PSS fractions with low M/G ratio and high Mw were the main reasons to bring about bleeding by excessively suppressing coagulant factors activities and weakening platelet function. Our results suggested that it is very necessary to control the M/G ratio and the range of Mw of PSS to guarantee its safety and effectiveness in clinical.

Impact of fulvic acids on bio-methanogenic treatment of municipal solid waste incineration leachate.

A considerable amount of leachate with high fulvic acid (FA) content is generated during the municipal solid waste (MSW) incineration process. This incineration leachate is usually processed by downstream bio-methanogenic treatment. However, few studies have examined the impact that these compounds have on methanogenesis and how they are degraded and transformed during the treatment process. In this study, a laboratory-scale expanded granular sludge bed (EGSB) reactor was operated with MSW incineration leachate containing various concentrations of FA (1500 mg/L to 8000 mg/L) provided as the influent. We found that FA degradation rates decreased from 86% to 72% when FA concentrations in the reactor were increased, and that molecular size, level of humification and aromatization of the residual FA macromolecules all increased after bio-methanogenic treatment. Increasing FA influent concentrations also inhibited growth of hydrogenotrophic methanogens from the genus Methanobacterium and syntrophic bacteria from the genus Syntrophomonas, which resulted in a decrease in methane production and a concomitant increase in CO2 content in the biogas. Sequences most similar to species from the genus Anaerolinea went up as FA concentrations increased. Bacteria from this genus are capable of extracellular electron transfer and may be using FA as an electron acceptor for growth or as a shuttle for syntrophic exchange with other microorganisms in the reactor. In order to determine whether FA could serve as an electron shuttle to promote syntrophy in an anaerobic digester, co-cultures of Geobacter metallireducens and G. sulfurreducens were grown in the presence of FA from raw leachate or from residual bioreactor effluent. While raw FA stimulated electron transfer between these two bacteria, residual FA did not have any electron shuttling abilities, indicating that FA underwent a significant transformation during the bio-methanogenic treatment process. These results are significant and should be taken into consideration when optimizing anaerobic bioreactors used to treat MSW incineration leachate high in FA content.

Study on quality control of sulfated polysaccharide drug, propylene glycol alginate sodium sulfate (PSS).

The combination of biological and chemical analysis methods was developed to improve quality control of propylene glycol alginate sodium sulfate (PSS), a sulfated polysaccharide drug. The allergic and anticoagulant assays revealed that PSS fractions with higher Mw and lower M/G ratio may have allergic response and bleeding risks. HPLC with pre-column derivatization, HPGPC and IC methods were combined to analyze 10 batches of PSS samples from different manufacturers. The results showed that the quality of these PSSs varied greatly which in turn led to the unstable anticoagulant activity and side effects. The study indicated that PSS with high purity, M/G ratio above 1.5, Mw of ∼9kD and DS of 9.0-13.0% can ensure clinical efficacy and low incidence of adverse drug reactions. In conclusion, the combined methods would be in favor of guiding manufacture and quality control of PSS to guarantee its effectiveness and safety.

Determination of M/G ratio of propylene glycol alginate sodium sulfate by HPLC with pre-column derivatization.

A reliable high performance liquid chromatography with pre-column derivatization method was developed for the determination of the mannuronic acid (M)/guluronic acid (G) ratio of propylene glycol alginate sodium sulfate (PSS). The hydrolysis conditions of PSS were investigated by four degradation methods based on the degree of destruction of M and G, and the chromatographic separation conditions were also optimized. A satisfactory resolution of M and G was achieved with a KP-C18 column using 0.1 mol/L phosphate buffer (pH 7.0)-acetonitrile (83/17, v/v) as a mobile phase, after PSS was hydrolyzed with 0.1 mol/L sulfuric acid and labeled with 1-phenyl-3-methyl -5-pyrazolone. The M/G ratio of PSS determined by this method was in good accordance with that obtained by the (1)H NMR method with a desulfurization strategy. Our method is rapid, sensitive, accurate and reproducible. The limit of detection was found to be 0.25 µg/mL for M and 0.40 µg/mL for G.