The causal relationship between gut microbiota and bone mineral density: a Mendelian randomization study.

Background: The gut microbiota has emerged as an intriguing and potentially influential factor in regulating bone health. However, the causal effect of the gut microbiota on bone mineral density (BMD) appears to differ throughout various life stages. Methods: We conducted a Mendelian randomization (MR) analysis to investigate the potential causal relationship between gut microbiota and BMD in five distinct age groups: 0-15, 15-30, 30-45, 45-60, and 60 years and older. The analysis employed three different methods, namely MR-Egger, weighted median, and Inverse-variance weighting, to ensure the robustness of our findings, a series of sensitivity analyses were also conducted, such as horizontal pleiotropy tests, heterogeneity tests, and leave-one-out sensitivity tests. Results: In the age group of 0-15 years, Eubacterium_fissicatena_group and Eubacterium_hallii_group were identified as risk factors for BMD. During the 15-30 age group, Phascolarctobacterium, Roseburia, and Ruminococcaceae_UCG_003 were found to be protective factors for BMD. In the 30-45 age group, Lachnospira genus demonstrated a protective effect on BMD, while Barnesiella and Lactococcus were identified as risk factors for BMD. Moving on to the 45-60 age group, Eubacterium_ventriosum_group, Lachnospiraceae_UCG_004, and Subdoligranulum were observed to be protective factors for BMD, while Eubacterium_coprostanoligenes_group, Fusicatenibacter, and Lactococcus were associated with an increased risk of BMD. In individuals aged 60 years and older, Fusicatenibacter and Ruminococcaceae_UCG_002 were also noted as risk factors for BMD. Conversely, Eubacterium_ruminantium_group, Ruminococcus_gauvreauii_group, Alistipes, and Coprococcus_3 were found to be protective factors for BMD, whereas Barnesiella and Sellimonas were identified as risk factors for BMD. Conclusion: A robust causal relationship between gut microbiota and bone mineral density (BMD) exists throughout all stages of life, with Firmicutes phylum being the primary group associated with BMD across age groups. Gut microbiota linked with BMD primarily belong to the Firmicutes phylum across age groups. The diversity of gut microbiota phyla associated with BMD depicts relatively stable patterns during the ages of 0-45 years. However, for individuals aged 45 years and above, there is an observed increase in the number of gut microbiota species linked with BMD, and by the age of 60 years, a trend toward an increase in the Bacteroidetes phylum categories is proposed.

Circulating metabolites and depression: a bidirectional Mendelian randomization.

Background: Studies have shown an association between depression and circulating metabolites, but the causal relationship between them has not been elucidated. The purpose of this study was to elucidate the causal relationship between circulating metabolites and depression and to explore the role of circulating metabolites in depression. Methods: In this study, the top single-nucleotide polymorphisms (SNPs) associated with circulating metabolites (n = 24,925) and depression (n = 322,580) were obtained based on the publicly available genome-wide association study using two-sample Mendelian randomization (MR). SNP estimates were summarized through inverse variance weighted, MR Egger, weighted median, MR pleiotropy residual sum and outlier, and "leave-one-out" methods. Results: Apolipoprotein A-I (OR 0.990, 95% CI 981-0.999) and glutamine (OR 0.985, 95% CI 0.972-0.997) had protective causal effects on depression, whereas acetoacetate (OR 1.021, 95% CI 1.009-1.034), glycoproteins (OR 1.005, 95% CI 1.000-1.009), isoleucine (OR 1.013, 95% CI 1.002-1.024), and urea (OR 1.020, 95% CI 1.000-1.039) had an anti-protective effect on depression. Reversed MR showed no effect of depression on the seven circulating metabolites. Conclusion: In this study, MR analysis showed that apolipoprotein A-I and glutamine had a protective effect on depression, and acetoacetate, glycoprotein, isoleucine, glucose, and urea may be risk factors for depression. Therefore, further research must be conducted to translate the findings into practice.

Combined metabolomics and network pharmacology to elucidate the mechanisms of Dracorhodin Perchlorate in treating diabetic foot ulcer rats.

Background: Diabetic foot ulcer (DFU) is a severe chronic complication of diabetes, that can result in disability or death. Dracorhodin Perchlorate (DP) is effective for treating DFU, but the potential mechanisms need to be investigated. We aimed to explore the mechanisms underlying the acceleration of wound healing in DFU by the topical application of DP through the combination of metabolomics and network pharmacology. Methods: A DFU rat model was established, and the rate of ulcer wound healing was assessed. Different metabolites were found in the skin tissues of each group, and MetaboAnalyst was performed to analyse metabolic pathways. The candidate targets of DP in the treatment of DFU were screened using network pharmacology. Cytoscape was applied to construct an integrated network of metabolomics and network pharmacology. Moreover, the obtained hub targets were validated using molecular docking. After the topical application of DP, blood glucose, the rate of wound healing and pro-inflammatory cytokine levels were assessed. Results: The levels of IL-1, hs-CRP and TNF-α of the Adm group were significantly downregulated. A total of 114 metabolites were identified. These could be important to the therapeutic effects of DP in the treatment of DFU. Based on the network pharmacology, seven hub genes were found, which were partially consistent with the metabolomics results. We focused on four hub targets by further integrated analysis, namely, PAH, GSTM1, DHFR and CAT, and the crucial metabolites and pathways. Molecular docking results demonstrated that DP was well combined with the hub targets. Conclusion: Our research based on metabolomics and network pharmacology demonstrated that DP improves wound healing in DFU through multiple targets and pathways, and it can potentially be used for DFU treatment.

Experimental Study on Vibratory Compaction Behavior of Tunneling Rock Wastes Used as Unbound Permeable Aggregate Base Materials.

The tunneling rock wastes (TRW) have been increasingly generated and stockpiled in massive quantities. Recycling them for use as unbound granular pavement base/subbase materials has become an alternative featuring low carbon emission and sustainability. However, the field compaction of such large-size, open-graded materials remains challenging, thus affecting post-construction deformation and long-term stability of such pavement base/subbase layers. This study conducted a series of proctor compaction and new plate vibratory compaction tests to analyze the compaction characteristics of such TRW materials. A total of six different open gradations were designed from particle packing theory. In addition, the effects of gradation and compaction methods on the compaction characteristics, particle breakage of TRW materials, and the optimal combination of vibratory parameters were investigated by normalizing the curves of achieved dry density versus degree of saturation for various combinations of gradations, compaction methods, and compaction energy levels. The post-compaction characteristics of interparticle contact, pore structure, and particle breakage were analyzed from the X-ray computed topography (XCT) scanning results of TRW specimens with different gradations. The findings showed that the gravel-to-sand ratio (G/S) based gradation design method can effectively differentiate distinct types of particle packing structures. There exists an optimal G/S range that could potentially result in the highest maximum dry density, the lowest particle breakage, and the best pore structure of compacted unbound permeable aggregate base (UPAB) materials. The achieved dry density (ρd) of UPAB materials subjected to vibratory plate compaction exhibited three distinct phases with compaction time, from which the optimal excitation frequency range was found to be 25-27 Hz and the optimal combination of vibratory parameters were determined. The normalized compaction curves of degree of saturation versus achieved dry density were found insensitive to changes in material gradations, compaction methods and energy levels, thus allowing for a more accurate evaluation and control of field compaction quality.

Global Trends in Research of Gouty Arthritis Over Past Decade: A Bibliometric Analysis.

Gouty arthritis (GA), as a multifactorial disease, is characterised by intense pain, active inflammation symptoms, and swollen joints. It has utterly complex pathogenesis, of which the amount of research publications on GA has increased during the last few decades. A bibliometric analysis was carried out to investigate the trends, frontiers, and hot spots in global scientific output in GA research over the last decade. We retrieved the Science Citation Index Expanded (SCI-Expanded) of the Web of Science Core Collection (WoSCC) for publications and recorded information published from 2012 to 2021. we carried out the bibliometric analysis and visualisation analysis of the overall distribution of annual outputs, leading countries, active institutions, journals, authors, co-cited references, and keywords with the VOSviewer and CiteSpace. The impact and quality of papers were assessed using a global citation score (GCS). We retrieved 2052 articles and reviews in total. The annual number of publications (Np) related to GA research has increased during the latest decade. China published the most papers, and the USA achieved the highest H-index and number of citations (Nc). The League of European Research Universities (LERU) and Clinical Rheumatology (Clin Rheumatol) are the most productive institutions and periodicals. The total GCS of the paper written by Kottgen, A. in 2013 was 479, ranking the first. The most common keywords were "Gout," "hyperuricemia," and "gouty arthritis." This research revealed that though there was a slight fluctuation in publications related to GA, the Np raised on the whole. China was an enormous creator, and the USA was an influential nation in this domain. The top three contributor authors were Dalbeth, N., Singh, JA., and Choi, HK. There were few investigations on the treatment of GA by Chinese medicine monomer, and the "mechanism," "pathway", "nf- kappa-b", "injury", "receptor", and "animal model" were growing research hotspots. Our research illustrated the hotspots of research and development trends in the research field of GA during the last decade. Recognition of the most critical indicators (researchers, countries, institutes, and journals for the release of GA research), hotspots in the research field of GA can be helpful for countries, scholars, and policymakers in this field to understand GA better make decisions.

Quality of Evidence Supporting the Role of Tripterygium Glycosides for the Treatment of Diabetic Kidney Disease: An Overview of Systematic Reviews and Meta-Analyses.

Background: Tripterygium glycosides (TG) is widely used in the treatment of diabetic kidney disease (DKD) in China. To systematically assess and synthesize the available evidence, we present an overview of systematic reviews (SRs) and meta-analyses (MAs) on the topic of TG interventions for DKD. Methods: SRs/MAs on TG interventions for DKD were comprehensively searched in seven databases. Methodological quality, risk of bias, reporting quality, and quality of evidence were assessed using the Assessment of Multiple Systematic Reviews 2 (AMSTAR-2), the Risk of Bias in Systematic (ROBIS) scale, the list of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), as well as the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. Results: This overview includes 13 SRs/MAs that use quantitative calculations to comprehensively assess various outcomes in TG interventions for DKD. The methodological quality, reporting quality, and risk of bias of SRs/MAs, and the quality of evidence for outcome indicators are unsatisfactory. Limitations of the included SRs/MAs consist in the lack of essential procedures such as protocol registration, screening of duplicate study, provision of the list of excluded studies, and assessment of publication bias. Besides, the reliance on small samples for quantitative synthesis of effect sizes also constitutes an important limitation. Conclusion: TG may be a potential complementary treatment modality to DKD therapy. However, this conclusion must be treated with caution as the quality of the evidence provided by SRs/MAs is generally low.

Quality of Evidence Supporting the Role of Curcuma Longa Extract/Curcumin for the Treatment of Osteoarthritis: An Overview of Systematic Reviews.

Background: Well known for its good anti-inflammatory effect, curcuma longa extract (CLE)/curcumin (C) has a potential effect on osteoarthritis (OA), and a large number of researchers have completed several systematic reviews/meta-analyses (SRs/MAs) in this research area. However, the methodological and evidentiary quality of these SRs/MAs need to be further evaluated, and whether these findings provide reliable evidence for clinicians remains controversial. Methods: Two researchers collected data from seven databases for SRs/MAs that are about randomized controlled trials (RCTs) on CLE/C for OA. Assessment was made for the SRs/MAs included in this article by means of the Assessment System for Evaluating Methodological Quality 2 (AMSTAR-2), the Risk of Bias in Systematic (ROBIS) scale, the list of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. Results: Nine published SRs/MAs were included in our study. According to the results of the AMSTAR-2 assessment, only one SR/MA was assessed as high quality. According to the ROBIS evaluation results, only 2 SRs/MAs have a low risk of bias. According to the results of the PRISMA checklist assessment, only 2 SRs/MAs studies fully reported the checklist, while other studies had reporting flaws. According to GRADE, a total of 59 effect sizes extracted from the included SRs/MAs were evaluated, among which no effect size was rated as high. Conclusions: CLE/C may be an effective and safe complementary treatment for OA. However, further standard SRs/MAs and RCTs are needed to provide an evidence-based medical rationale for this.

Worldwide Research Trends on Diabetic Foot Ulcers (2004-2020): Suggestions for Researchers.

OBJECTIVES: Diabetic foot ulcer (DFU) is one of the devastating complications of diabetes. It has high mortality and disability rates. The number of research articles on DFUs has increased. This study was designed to explore the global trends and research hotspots of DFUs to benefit researchers in shaping future research directions. METHODS: Literatures relating to DFU from 2004 to 2020 were retrieved from the Science Citation Index Expanded (SCI-expanded) of Web of Science Core Collection (WoSCC). The current status of DFU research (including publications, journals, the performances of relevant countries, institutions, and authors and the research trends and hotspots of DFU) was analyzed with the WoSCC. VOSviewer v1.6.10.0 was utilised for cocitation, coauthorship, cooccurrence analyses, and bibliographic coupling. RESULTS: A total of 5869 publications on DFUs were retrieved. We performed a longitudinal review of publications over 17 years: 4500 articles and 865 review articles on DFUs published from 2004 to 2020 were analyzed. The total citation was 107,296. The USA (n = 1866), England (n = 606), and China (n = 599) were the three largest contributors. The University of Washington had the greatest number of publications within this time period (n = 103), and it had the most cooperative units and was in the core position in all research institutions, followed by the University of Manchester (n = 94) and the University of Miami (n = 92). Armstrong DG (91/1.69%) and Lavery LA (55/1.19%) should be regarded as scholars who have made outstanding contributions. The top journal with the greatest total link strength was Diabetes Care. Analysis showed that the global research hotspots of DFU focused on lower limb amputation, diabetic foot infection, and treatment and management of DFU. Studies on osteomyelitis, wound therapy and management, multidisciplinary integration and mechanism of DFUs, and its related diseases are the research fronts that should be closely watched in the future. CONCLUSIONS: This study revealed the current research status and hotspots in the domain of DFU over the past 17 years, which can help researchers to further pinpoint potential perspectives on hot topics and research frontiers.

Advances in Experimental and Clinical Research of the Gouty Arthritis Treatment with Traditional Chinese Medicine.

Gouty arthritis (GA) is a multifactorial disease whose pathogenesis is utterly complex, and the current clinical treatment methods cannot wholly prevent GA development. Western medicine is the primary treatment strategy for gouty arthritis, but it owns an unfavorable prognosis. Therefore, the prevention and treatment of GA are essential. In China, traditional Chinese medicine (TCM) has been adopted for GA prevention and treatment for thousands of years. Gout patients are usually treated with TCM according to their different conditions, and long-term results can be achieved by improving their physical condition. And TCM has been proved to be an effective method to treat gout in modern China. Nevertheless, the pharmacological mechanism of TCM for gout is still unclear, which limits its spread. The theory of prevention and treatment of gout with TCM is more well acknowledged in China than in abroad. In this article, Chinese herbs and ancient formula for gout were summarized first. A total of more than 570 studies published from 2004 to June 2021 in PubMed, Medline, CNKI, VIP, Web of Science databases and Chinese Pharmacopoeia and traditional Chinese books were searched; the current status of TCM in the treatment of GA was summarized from the following aspects: articular chondrocyte apoptosis inhibition, antioxidative stress response, inflammatory cytokine levels regulation, uric acid excretion promotion, immune function regulation, uric acid reduction, and intestinal flora improvement in subjects with gout. The literature review concluded that TCM has a specific curative effect on the prevention and treatment of GA, particularly when combined with modern medical approaches. However, lacking a uniform definition of GA syndrome differentiation and the support of evidence-based medicine in clinical practice have provoked considerable concern in previous studies, which needs to be addressed in future research.

Study on the molecular mechanism of Guizhi Jia Shaoyao decoction for the treatment of knee osteoarthritis by utilizing network pharmacology and molecular docking technology.

BACKGROUND AND OBJECTIVE: Guizhi Jia Shaoyao decoction (GSD) is widely used in the clinical treatment of knee osteoarthritis (KOA). However, the underlying molecular mechanisms remain unclear. The aim of this study was to explore functional mechanisms of GSD in treating KOA by utilizing network pharmacology-based approaches. METHODS: Candidate components and targets of GSD were retrieved from the Traditional Chinese Medicine Systems Pharmacology database. NCBI, Genecards, Drugbank, and Therapeutic Target Database (TTD) were used to establish a target database for KOA. Then, an interactive network diagram of "drugs-active components-targets" was plotted with Cytoscape open source bioinformatics software. A protein-protein interaction network was constructed and related protein interaction relationships were analyzed based on the STRING database. Gene ontology analysis and Kyoto Encyclopedia of Genes and Genomes pathway-enrichment analysis were conducted based on intersected targets. Molecular docking provided an assessment tool for verifying binding of components and targets. It was performed by AutoDock molecular modeling simulation software. RESULTS: In all, 103 active components were successfully identified, and corresponding 133 targets were searched for treating KOA. Functional enrichment analysis suggested that GSD exerts its pharmacological effect in treating KOA by regulating multiple pathways, such as PI3K-Akt, tumor necrosis factor, Toll-like receptor (TLR), and nuclear factor kappa B signaling pathways. Molecular docking analysis depicted that representative components bound firmly to key targets. CONCLUSION: This study revealed the synergistic effects of multiple components, targets, and pathways of GSD for treating KOA. This would enhance the understanding of potential molecular mechanisms of GSD for treating KOA and lay a foundation for further experimental research.

Efficacy and Safety of Acupuncture Combined with Herbal Medicine in Treating Gouty Arthritis: Meta-Analysis of Randomized Controlled Trials.

BACKGROUND: Gouty arthritis is a common metabolic disease caused by long-term purine metabolism and elevated serum uric acid. In recent years, the incidence of gouty arthritis has been increasing year by year. As an effective method for treating gouty arthritis, acupuncture combined with herbal medicine has been widely used in clinical practice. However, the evidence for the treatment needs to be evaluated through systematic review and meta-analysis. Methods. The Cochrane Library, PubMed, Web of Science, EMBASE, China CBM database, Clinical Trials, CNKI, China Wanfang database, and VIP information database were searched from the establishment of each database to March 2021. Randomized controlled trials (RCTs) were included in the study, and the therapeutic effects of acupuncture combined with herbal medicine versus conventional therapy, or acupuncture combined with herbal medicine versus anti-inflammatory drugs, or acupuncture combined with herbal medicine versus acupuncture/herbal medicine alone were compared in the subjects with gouty arthritis. Two authors screened all references, assessed the risk of bias, and independently extracted the data. The binary outcome was summarized using 95% confidence intervals (CIs) and risk ratios (RRs). The overall quality of the evidence was assessed with hierarchy, and meta-analysis was performed with a random-effects model. RESULTS: A total of 14 randomized controlled trials (1,065 participants, 540 treatment groups, and 525 control groups) with treatment courses of 5 to 21 days were included. Acupuncture combined with herbal medicine and acupuncture was compared in three trials, acupuncture combined with herbal medicine and conventional therapy was compared in 14 of them, and acupuncture combined with herbal medicine and anti-inflammatory drugs was compared in 8 of them. The clinical efficacy (clinical symptoms, serological tests, and visual analogue scale (VAS) results) was significantly improved in the acupuncture combined with herbal medicine treatment group (P=0.0005, 95% CI 0.03 to 0.13; 687 participants; 8 trials), and the efficacy in reducing uric acid was also better (P < 0.00001; 95% CI -102.89, -68.37; 100 participants; 2 trials; evidence with moderate quality). The effect of acupuncture combined with herbal medicine was better than that of acupuncture alone (RR 1.22, 95%CI 1.06 to 1.41; 139 participants; 3 trials), the effect of acupuncture combined with herbal medicine was better than that of herbal medicine alone (RR 1.31 95%CI 1.08 to 1.57, 100 participants, 2 trials, evidence with moderate quality), and the effect of acupuncture combined with herbal medicine was better than that of colchicine (P = 0.02, RR 1.14 95%CI 1.02 to 1.27, 2 trials, evidence with moderate quality). The incidence of adverse events was considerably different between the two groups, and the acupuncture combined with herbal medicine group was significantly superior to the control group in terms of adverse events (P < 0.00001; 95% CI (0.08 to 0.32)). CONCLUSIONS: The efficacy of acupuncture combined with herbal medicine was better than conventional drug therapy in treating gouty arthritis. The study results must be interpreted with caution due to the high or unclear risk of bias of the trials included in the study. PROSPERO registration number: CRD42020202544. INPLASY registration number: 202090006.

Modified MIL-100(Fe) for enhanced photocatalytic degradation of tetracycline under visible-light irradiation.

Iron-based metal-organic frameworks (MOFs) with low cost and excellent photocatalytic potential are extremely attractive in the field of energy utilization and environmental remediation. In this study, a novel In2S3/MIL-100(Fe) photocatalyst was successfully synthesized by a facile solvothermal method for the first time. Several technologies (such as X-ray diffraction, scanning electron microscope, transmission electron microscope, and X-ray photoelectron spectroscopy) were used to characterize the as-obtained samples and demonstrate the successful combination of MIL-100(Fe) and In2S3. Experimental results showed that 18% of tetracycline (TC) was adsorbed under dark condition and another 70% of TC was degraded under visible-light irradiation when treating 100 mL of TC solution (10 mg/L) with 30 mg of In2S3/MIL-100(Fe) composites. The corresponding TC removal efficiency was almost 1.9 and 1.6 times higher than that of pure MIL-100(Fe) and In2S3, respectively. The mechanism investigations revealed that the heterojunction composite exhibited superior charge transfer than either MIL-100(Fe) or In2S3, and this caused more efficient separation of electron-hole pairs. As a result, more radicals and holes were generated in the composite, leading to better photocatalytic performance. This work highlights the powerful combination of MOFs and semiconductor, which is a promising approach to fabricate heterojunction photocatalyst for wastewater purification.

[Comparison study on phosphorus removal between single-stage oxic process and anaerobic/aerobic process].

To compare the efficiency of phosphorus removal between anaerobic/aerobic process (SBR1) and single-stage oxic process (SBR2), two SBRs were conducted using acetate as the sole carbon source which is the most extensive substrate in municipal wastewater. The results obtained from three months experiment showed that the phosphorus removal efficiency and the TP removed on a unit MLSS were 91.72%, 3.23 mg x g(-1) (SBR1)and 71.70%, 2.91 mg x g(-1) (SBR2) respectively during steady operation. The further study found that a significant increase of PHA associated with an decrease of glycogen in SBR1 while a significant synthesis of PHA increased with the accumulation of glycogen in SBR2, indicating glycogen was not essential for the synthesis of PHA in single-stage oxic process. Furthermore, obvious phosphorus release was observed in both SBRs during idle period, but the content of phosphorus released in SBR2 (13.28 mg x L(-1)) was significantly higher than that in SBR1 (2.6 mg x L(-1)). The possible reason for SBR1 and SBR2 exhibited different phosphorus removal efficiencies was that microorganisms in both SBRs had different cyclic storage and consumption process of energy storages during metabolic process.

Adsorption removal of cadmium and copper from aqueous solution by areca: a food waste.

Areca waste (AW) has been investigated as metal biosorbent for cadmium and copper from aqueous solution for its availability as food waste and also for its cellulosic matrix rich of potential metal binding active sites. The effect of various parameters on adsorption process such as contact time, solution pH, amount of AW and initial concentration of metal ions was studied at room temperature to optimize the conditions for maximum adsorption. Maximum metal sorption was found to occur at pH 5.6. Adsorption process revealed that the initial uptake was rapid and equilibrium was established about in 1h for cadmium and copper. The equilibrium sorption data for single metal systems at pH 5.6 were described by the Langmuir, Freundlich and D-R isotherm models. The adsorption isotherm studies clearly indicated that the adsorptive behaviour of metal ions on AW not only the Langmuir assumptions but also the Freundlich and the D-R assumptions. The highest value of Langmuir maximum uptake, (b), was found for cadmium (1.12 mg/g) and copper (2.84 mg/g). Similar Freundlich empirical constants, K, were obtained for cadmium (1.086) and copper (1.119). Ion-exchange and surface adsorption might be involved in the adsorption process of cadmium and copper. Desorption studies revealed that cadmium and copper can be easily removed from AW by altering the pH values of the solution using HNO(3), indicating that AW are a promising adsorbent for wastewater treatment.

[Complete nitritation process in an biofilm moving bed system by controlling pH].

Complete nitritation process in an biofilm moving bed system was started-up by inoculating nitrobacteria and controlling pH, and the effects of nitrogen loading rate (NLR) and hydraulic retention time (HRT) on the stability of the system were investigated. The results showed that the system could achieve complete nitritation after 10 day's acclimation by controlling pH within the range of 7.7 - 8.2, under the conditions of temperature (30 +/- 1) degrees C, DO 1.5 - 2.0 mg/L, HRT 24 h,ammonia concentration 150 mg/L. Conversion rate of ammonia was above 96% and nitritation rate (NO2(-) -N/NO(x)(-) -N) was more than 95%. In addition, the system remained complete nitritation when NLR increased from 0.15 kg/(m3 x d) to 0.24 kg/(m3 x d), and conversion rate of ammonia was still above 90%, nitritation rate maintained at 96%, but the type of nitrification turned from completely nitritation to completely nitrification under the condition of over aeration by extended HRT under low NLR. However, it could be resumed by shortened HRT.