[Show abstract][Hide abstract] ABSTRACT: Avian influenza A(H7N9) virus (A(H7N9)) emerged in February 2013. Liver impairment of unknown cause is present in 29% of patients with A(H7N9) infection, some of whom experience severe liver injury. Hypoxic hepatitis (HH) is a type of acute severe liver injury characterized by an abrupt, massive increase in serum aminotransferases resulting from anoxic centrilobular necrosis of liver cells. In the intensive care unit (ICU), the prevalence of HH is ∼1%-2%. Here, we report a 1.8% (2/112) incidence of HH in the largest single-centre cohort of ICU patients with A(H7N9) infection. Both HH patients presented with multiple organ failure (MOF) involving respiratory, cardiac, circulatory and renal failure and had a history of chronic heart disease. On admission, severe liver impairment was found. Peak alanine aminotransferase (ALT) and aspartate aminotransferase (AST) values were 937 and 1281 U/L, and 3117 and 3029 U/L, respectively, in the two patients. Unfortunately, both patients died due to deterioration of MOF. A post-mortem biopsy in case 1 confirmed the presence of centrilobular necrosis of the liver, and real-time reverse transcription polymerase chain reaction of A(H7N9)-specific genes was negative, which excluded A(H7N9)-related hepatitis. The incidence of HH in A(H7N9) patients is similar to that in ICU patients with other aetiologies. It seems that patients with A(H7N9) infection and a history of chronic heart disease with a low left ventricular ejection fraction on admission are susceptible to HH, which presents as a marked elevation in ALT at the time of admission.
Preview · Article · Jan 2016 · Emerging Microbes and Infections
[Show abstract][Hide abstract] ABSTRACT: Background:
Systematic analysis of histopathological and serial virological changes of fatal influenza A(H7N9) cases is lacking.
Patients with A(H7N9) infection admitted to our intensive care unit during 10-23 April 2013 were included. Viral loads in the respiratory tract, as inferred from the cycle threshold (Ct) value of reverse transcription polymerase chain reaction (RT-PCR), and the serum hemagglutination inhibition (HAI) antibody titer, were analyzed. Postmortem biopsies of the lung, liver, kidney, spleen, bone marrow, and heart were examined.
Twelve patients (6 deaths, 6 survivors) were included. Median viral load was higher in sputa than the nasopharyngeal swabs for fatal cases (median Ct, 23 vs 30.5; P = .08). RT-PCR for A(H7N9) was positive in stool samples (4/6 [67%]) of fatal cases and (2/6 [33%]) of survivors, but was negative in the cerebrospinal fluid, urine, or blood of all patients. Nosocomial bacterial infections were more common in patients who died than in survivors (83% vs 50%). HAI titers increased by ≥4-fold in those with convalescent sera. Postmortem biopsy for 3 patients showed acute diffuse alveolar damage. Patient 1, who died 8 days after symptom onset, had intra-alveolar hemorrhage. Patients 2 and 3, who died 11 days after symptom onset, had pulmonary fibroproliferative changes. Reactive hemophagocytosis in the bone marrow and lymphoid atrophy in splenic tissues were compatible with laboratory findings of leukopenia, lymphopenia, and thrombocytopenia. Hypoxic and fatty changes of kidney and liver tissues are compatible with impaired renal or liver function.
Fatal A(H7N9) infection was characterized by viral and secondary bacterial pneumonia with 67% having positive RT-PCR in stool.
Preview · Article · Aug 2013 · Clinical Infectious Diseases
[Show abstract][Hide abstract] ABSTRACT: In recent years, nitrogen pollution has been increasingly serious in natural waters including drinking source water. A simulated river biofilm reactor fed with contaminated drinking source water was established to evaluate the effects of dissolved oxygen (DO) partitioning and step feeding on the nitrogen removal performance and biofilm microbial community. Results showed that after the hydraulic retention time of anoxic zone extending and step feeding, the effluent concentration of ammonia was below 0.2 mg L−1, and the removal efficiency of total nitrogen increased from 12.02% ± 4.59% to 34.98% ± 2.65%, which indicated the occurrence of simultaneous nitrification and denitrification. The results of denaturing gradient gel electrophoresis showed that the microbial community of biofilm obviously shifted via DO controlling and step feeding. Low DO concentration favored the enrichment of denitrifying bacteria and coexistence of algae and bacteria, and the pattern of step feeding could increase the community abundance. The dominant heterotrophic bacteria species of biofilm in oligotrophic niche belonged to Hyphomicrobium sp., Pseudomonas sp., Chloroflexi sp., Enterobacter sp., Pantoea sp., and Synechococcus sp., which were mostly associated with denitrification and refractory organics utilization. It was worth noting that the ammonia-oxidizing bacteria (AOB) community of biofilm was stable throughout the whole experiment, and Nitrosomonas sp. was the predominant AOB in the oligotrophic niche.
No preview · Article · Jul 2012 · International Biodeterioration & Biodegradation
[Show abstract][Hide abstract] ABSTRACT: An aerobic denitrifier was isolated from the Hua-Jia-Chi pond in China and identified as Pseudomonas mendocina 3-7 (Genbank No. HQ285879). This isolated strain could express periplasmic nitrate reductase which is essential for aerobic denitrification occurred when the dissolved oxygen (DO) level maintains at 3-10 mg L(-1).
To determine whether the ability of isolated strain is exhibited in the bioremediation of polluted drinking source water, the heterotrophic nitrification and aerobic denitrification characteristics of P. mendocina 3-7 under different cultural conditions such as oxygen level, nitrate and organic concentrations were studied from the nitrogenous balance in the paper.
By measuring the nitrogen balance in all experiments under different culture conditions, the removal of total organic carbon and ammonium was positively correlated with total nitrogen removal, especially under high substrate level. With substrate concentration decreasing, ammonium and nitrate removal occurred separately, and ammonium was completely utilized first under low substrate concentration. Compared to that under high substrate level, the specific growth rate of P. mendocina 3-7 was not low under the low substrate level and the pollutant removal efficiencies remained high, which implies the stronger nitrogen removal and acclimatization capacities of the strain in oligotrophic niches.
No preview · Article · Mar 2012 · Environmental Science and Pollution Research
[Show abstract][Hide abstract] ABSTRACT: In recent years, nitrogen pollution has been increasingly serious in environmental waters in China, especially in drinking source. Seven predominant aerobic denitrifiers were isolated and characterized from the oligotrophic ecosystems. Based on their phenotypic and phylogenetic characteristics, the isolates were identified as the genera of Pseudomonas, Achromobacter and Acinetobacter, and all isolates could express periplasmic nitrate reductase which was essential for the aerobic denitrification. The growth rates of the isolates were at 0.30-0.83 h(-1), and obvious denitrification occurred when the dissolved oxygen (DO) level maintained at 3-10 mg L(-1). The isolates were able to conduct heterotrophic nitrification for realizing completely nitrogen removal in aerobic oligotrophic niche. Furthermore, three strains especially Pseudomonas sp.3-7 showed outstanding capacities of extracellular polymeric substances (EPS) secretion and aggregation. Results demonstrated that the isolation of aerobic denitrifiers favored the bioremediation of oligotrophic ecosystems.
No preview · Article · Mar 2012 · Bioresource Technology
[Show abstract][Hide abstract] ABSTRACT: The start-up pattern of biofilm remediation system affects the biofilm characteristics and operating performances. The objective of this study was to evaluate the performances of the contaminated source water remediation systems with different start-up patterns in view of the pollutants removal performances and microbial community succession.
The operating performances of four lab-scale simulated river biofilm reactors were examined which employed different start-up methods (natural enrichment and artificial enhancement via discharging sediment with influent velocity gradient increase) and different bio-fillers (Elastic filler and AquaMats® ecobase). At the same time, the microbial communities of the bioreactors in different phases were analyzed by polymerase chain reaction, denaturing gradient gel electrophoresis, and sequencing.
The pollutants removal performances became stable in the four reactors after 2 months' operation, with ammonia nitrogen and permanganate index (COD(Mn)) removal efficiencies of 84.41-94.21% and 69.66-76.60%, respectively. The biomass of mature biofilm was higher in the bioreactors by artificial enhancement than that by natural enrichment. Microbial community analysis indicated that elastic filler could enrich mature biofilm faster than AquaMats®. The heterotrophic bacteria diversity of biofilm decreased by artificial enhancement, which favored the ammonia-oxidizing bacteria (AOB) developing on the bio-fillers. Furthermore, Nitrosomonas- and Nitrosospira-like AOB coexisted in the biofilm, and Pseudomonas sp., Sphaerotilus sp., Janthinobacterium sp., Corynebacterium aurimucosum were dominant in the oligotrophic niche.
Artificial enhancement via the combination of sediment discharging and influent velocity gradient increasing could enhance the biofilm formation and autotrophic AOB enrichment in oligotrophic niche.
No preview · Article · Nov 2011 · Environmental Science and Pollution Research
[Show abstract][Hide abstract] ABSTRACT: Aiming at the carbon source limitation of denitrification in oligotrophic habitat, this paper studied the effects of intermittent aeration on the nitrogen-removal capability of biological contact oxidation remediation system for micro-polluted source water, and approached the feasibility and process mechanism of shortcut nitrification and denitrification in the system. Under the condition of 8 h-16 h anoxic-aerobic phase (I), the remediation system performed stably, and its average removal efficiency of ammonium (NH4+ -N), permanganate index (COD(Mn)), and total nitrogen (TN) was 93.0%, 78.1%, and 19.4%, respectively. Under the condition of 16 h-8 h anoxic-aerobic phase (II), the NH4+ -N and COD(Mn) removal efficiency still maintained at 81.2% and 76.4%, respectively, the accumulation of nitrite (NO2- -N) was significant, and the removal efficiency of TN reached more than 50%. The nitrogen transformation characteristics in the system during a cycle under condition II demonstrated that at the prerequisite of effluent NH4+ -N and DO concentrations reaching the standards, shortening aerobic phase length could maintain the DO concentration at 0. 5 -1.5 mg L(-1) in a long term, inhibit the growth and activity of nitrite-oxidizing bacteria, and thereby, NO2- -N had an obvious accumulation, and the nitrogen removal via shortcut nitrification-denitrification in the biological contact oxidation remediation system for micro-polluted source water was finally achieved.
No preview · Article · Apr 2011 · Ying yong sheng tai xue bao = The journal of applied ecology / Zhongguo sheng tai xue xue hui, Zhongguo ke xue yuan Shenyang ying yong sheng tai yan jiu suo zhu ban
[Show abstract][Hide abstract] ABSTRACT: Two simulated river bioreactors with elastic filler and AquaMats were applied to remediate micro-polluted source water. Under intermittent aeration and gradual increase of aeration intensity, the biofilm reactor with elastic filler was successful start-up within 50 days, and average removal efficiencies of permanganate index, NH4(+) -N were 78.2% and 93.5%, respectively, but the removal efficiencies of the reactor with AquaMats were more than 70% and 80% after two weeks. On the condition of aerobic to anoxic ratio of 3 h: 3 h and aeration intensity of 250 L x h(-1), elastic filler was more efficient for the removal of permanganate index, NH4(+) -N, TN and TP. The pollutant removal of AquaMats was strongly enhanced when the aerobic to anoxic ratio and aeration intensity changed to 2 h :4 h and 120 L x h(-1), which suggested its potential of energy saving. Microscopic observation revealed that the surface of elastic filler was fully surrounded with filamentous bacteria and more inorganic particulate matter after successful start-up of the reactor, and the biofilm attaching to AquaMats was of higher microbial population diversity. The results indicated that elastic filler with homogeneous biofilm had a strong retention capacity for its radial structure, and the AquaMats with microporous structure was more suitable for the enrichment of different functional microorganisms and enhanced the collaborative removal of multiple pollutants.
No preview · Article · Nov 2010 · Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.]
[Show abstract][Hide abstract] ABSTRACT: The catalytic ozonation of industrial wastewater containing chloro and nitro aromatic compounds was carried out in a semi-continuous lab-scale reactor using Mn/Co modified porous diatomaceous ceramic fillings as catalysts. Results showed that the Mn/Co modified filling significantly enhanced the removal efficiencies of TOC and COD, as well as the ozone utilization efficiency over non-catalytic ozonation. A closer of scrutiny of catalytic ozonation system at neutral pH found that almost complete decolorization and removal of chloro and nitro pollutants were achieved after 80 min reaction time. A sharp decrease in pH and TOC and the formation of high concentrations of nitrate and chloride were observed at initial stage of ozonation. The effect of catalytic ozonation was evaluated on the subsequent biological treatment through biodegradability and acute toxicity tests. Catalytic ozonation significantly increased the biodegradability of industrial wastewater in company with toxicity reduction. Thus using coupled catalytic ozonation-sequencing batch reactor under neutral condition may be efficient and cost-effective in treating the wastewater.