Internal-loop granular sludge bed nitrifying reactor is a new type of aerobic nitrifying equipment and has shown a good potential for nitrification. To study the flow pattern and construct the flow model, the tracer tests were performed using pulse stimulus-response technique. Based on the experimental results, the flow pattern in the settling section and the circulating section of reactor were analyzed by axial dispersion model and tank-in-series model, respectively. The dispersion number D/uL of 0.00148 in the settling section indicates that its flow pattern is similar to plug flow reactor (PFR), and the series number N of 1.021 in the circulating section indicates that its flow pattern is similar to continuously stirred tank reactor (CSTR). During steady state, the theoretic hydraulic retention time is 360 min, and the actual hydraulic retention time is 341.2 min. The percentage of dead space in the reactor is 5.22%, thereinto the dead space caused by biomass (db ) is 0.75 % and the hydraulic dead space (dh) is 4.47%, which shows that the structural performance of the reactor is excellent. Based on the experiments and analysis, a model of CSTR and PFR in series was constructed. The actual hydraulic retention time distribution of the reactor is in good agreement with the model predictions. Since the relative error between them is 8.56%, the model is accurate to describe the flow pattern. The results have laid a foundation for the kinetic model of the reactor and will be helpful for its design and operation.
Bioreactors ; Kinetics ; Models, Theoretical ; Nitrites ; metabolism ; Sewage

AIMTo establish a fluorospectrophotometric assay for the measurement of nitrite in blood.

METHODSInterference from hemoglobin and other blood ingredients was removed through sulfuric acid and phosphotungstic acid pretreatment. Fluorescence of 1-[H]-naphthotriazole from the reaction of 2,3-diaminonaphthalene with nitrite was determined with fluorospectrophotometry.

RESULTSThe following conditions were proper: Serum or plasma was treated with sulfuric acid and phosphotungstic acid pretreatment for two times, 2,3-diaminonaphthalene of 0.63 mmol x (L(-1)) was used, reaction solution pH and final pH were about 1.60 and 1.70 respectively, solution containing 2,3-diaminonaphthalene and supernatant after pretreatment was water-bathed at 20 degrees C for 15 minutes. The lower limit of detection was 24.27 nmol x L(-1). Nitrite determined in peripheral blood of healthy people was (10.91 +/- 2.38) micromol x L(-1), and its 95% distribution range was (6.24-15.57) micromol x L(-1).

CONCLUSIONIt's a relatively sensitive, specific, simple method. It's of some value to the study of nitric oxide.

Nitrites play multiple characteristic functions in invasion and metastasis of hepatic cancer cells, but the exact mechanism is not yet known. Cancer cells can maintain the malignant characteristics via clearance of excess mitochondria by mitophagy. The purpose of this article was to determine the roles of nitrite, reactive oxygen species (ROS) and hypoxia inducing factor 1 alpha (HIF-1 α) in mitophagy of hepatic cancer cells. After exposure of human hepatocellular carcinoma SMMC-7721 cells to a serial concentrations of sodium nitrite for 24 h under normal oxygen, the maximal cell vitality was increased by 16 mg x (-1) sodium nitrite. In addition, the potentials of migration and invasion for SMMC-7721 cells were increased significantly at the same time. Furthermore, sodium nitrite exposure displayed an increase of stress fibers, lamellipodum and perinuclear mitochondrial distribution by cell staining with Actin-Tracker Green and Mito-Tracker Red, which was reversed by N-acetylcysteine (NAC, a reactive oxygen scavenger). DCFH-DA staining with fluorescent microscopy showed that the intracellular level of ROS concentration was increased by the sodium nitrite treatment. LC3 immunostaining and Western blot results showed that sodium nitrite enhanced cell autophagy flux. Under the transmission electron microscopy (TEM), more autolysosomes formed after sodium nitrite treatment and NAC could prevent autophagosome degradation. RT-PCR results indicated that the expression levels of COX I and COXIV mRNA were decreased significantly after sodium nitrite treatment. Meanwhile, laser scanning confocal microscopy showed that sodium nitrite significantly reduced mitochondrial mass detected by Mito-Tracker Green staining. The expression levels of HIF-1α, Beclin-1 and Bnip3 (mitophagy marker molecular) increased remarkably after sodium nitrite treatment, which were reversed by NAC. Our results demonstrated that sodium nitrite (16 mg x L(-1)) increased the potentials of invasion and migration of hepatic cancer SMMC-7721 cells through induction of ROS and HIF-1α mediated mitophagy.
Acetylcysteine ; pharmacology ; Autophagy ; Carcinoma, Hepatocellular ; pathology ; Cell Line, Tumor ; Cell Movement ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit ; metabolism ; Liver Neoplasms ; pathology ; Mitochondrial Degradation ; Neoplasm Invasiveness ; Nitrites ; metabolism ; Reactive Oxygen Species ; metabolism ; Sodium Nitrite ; pharmacology

Accidents, Occupational ; Adult ; Female ; Humans ; Male ; Middle Aged ; Nitrites ; poisoning

OBJECTIVETo compare the field epidemiological investigation and the criminal investigation on a nitrite poisoning event caused by deliberate contamination.

METHODSCases were searched according to the definition of the disease. Information on the histories of onset and diet of all the cases and normal population on site, were investigated face to face. Information as ingredients, processing and sales of foods was also gathered. Samples were collected and nitrite detection were performed. Relevant materials were searched, cases were interviewed and data related to criminal results were collected.

RESULTSPoisoned persons were staff of a big company in Longgang district of Shenzhen. The overall attack rate was 56.25% (63/112), with suspected and confirmed rates as 41.96% and 14.28%, respectively. The fatality rate was 3.17% (2/63). Clinical manifestation and effect of treatment were in accordance with the characteristics of an episode related to acute nitrite food poisoning in terms of factors as the time of onset, involving different age, sex and jobs of the patients. A total of 191 samples, including vomits from patients and seven batches of food and environment samples, were collected, with a positive detected rate of nitrite as 18.84%. Information gathered from the field environment, food distribution and processing supported the assumption that this was an incident of nitrite poisoning event with intention.

RESULTSfrom the criminal investigation showed that the suspect stemmed from the market management rivalry, bought nitrite, dissolved and spread on food stalls F9 and F10.

CONCLUSIONThis event of intentional nitrite release resulting in food contamination which further leading to food poisoning, was completely proved by the joint efforts of the teams and expertise from the field epidemiology survey and the criminal investigation.

Heterotrophic nitrification-aerobic denitrification (HN-AD) is an enrichment and breakthrough theory of traditional autotrophic nitrification heterotrophic denitrification. Heterotrophic nitrification-aerobic denitrifiers with the feature of wide distribution, strong adaptability and unique metabolic mechanism have many special advantages, including fast-growing, rapid biodegradability and long lasting activity, which can rapidly remove ammonia nitrogen, nitrate nitrogen (NO₃⁻-N) and nitrite nitrogen (NO₂⁻-N) under aerobic conditions simultaneously. Therefore, HN-AD bacteria show the important potential for denitrification under extreme conditions with high-salt, low-temperature or high-ammonia nitrogen environment, and HN-AD bacteria attract extensive attention in the field of biological denitrification of wastewater. In this review, we first introduce the previously reported HN-AD bacterial species which have denitrification performance in the extreme environments and state their typical metabolic mechanism. Then, we systematically analyze the nitrogen removal characteristics and potential under extreme conditions. We also briefly describe the progress in the application of HN-AD bacterial. Finally, we outlook the application prospects and research directions of HN-AD denitrification technology.
Aerobiosis ; Bacteria ; Denitrification ; Heterotrophic Processes ; Nitrification ; Nitrites ; Nitrogen

Homeostasis is a dynamic balance process of self-regulating. Biological systems remain stable through adapting to changing external conditions to maintain normal life activities. Homeostatic medicine is the science of studying homeostasis of human molecules, cells, organs and the whole body. It is a comprehensive discipline based on maintaining homeostasis to keep human health and assist for diseases prevention and diagnoses. Homeostatic medicine focuses on the whole body and on the role of homeostasis in health and disease, which is expected to provide new ideas and strategies for maintaining health as well as diagnosing and treating diseases. Nitric oxide (NO) plays an important role in the control of multisystem homeostasis. Nitrate is an important substance in regulating NO homeostasis through the nitrate-nitrite-NO pathway. Sialin, nitrate transporter which is located in the cell membrane and cytoplasm, mediates multiple cellular biological functions. The nitrate-nitrite-NO pathway and sialin-mediated biological functions play an important role in the regulation of body homeostasis.
Humans ; Nitrates/metabolism* ; Nitrites/metabolism* ; Homeostasis ; Nitric Oxide

BACKGROUND: We previously reported that ginsan, a polysaccharide extracted from Panax ginseng had an immunostimulatory activity such as mitogenic activity, activation of macrophages and killer cells, and production of a variety of cytokines which resulted in antitumor and antiseptic effects. We further purified alpha-(1-->6)-glucan and beta-(2-->6)-fructan from the ginsan with size exclusion and ion-exchange column chromatography successively. In this study, we performed the structure-based activity of ginsan by comparison with known polysacchrides such as beta-glucan, curdlan, laminarin, levan, dextran, lentinan and OK-432. METHODS: To investigate the immunostimulatory activity of several polysaccharide compounds, we investigated the stimulation of lymphocytes proliferation, the generation of activated killer cells and the secretion of nitrites from activated macrophages. RESULTS: Of polysaccharides tested, curdlan and ginsan stimulated lymphocyte proliferation, suggesting that the molecular weight and composition of polysaccharide are dependent on the mitogenic activity. The production of nitric oxide was significantly increased in curdlan, levan, ginsan and its fraction, indicating that fructan has also capacity to activate macrophages and may devote to kill pathogens. In addition, the activation of macrophages was seemed to be independent of molecular weight of polysaccharide. The generation of AK cells was exhibited in order of curdlan, OK-432> F1, ginsan, F3>levan>etc. The AK activity may be dependent on molecular weight and composition of polysaccharides. CONCLUSION: Unfortunately, purified polysaccharide from ginsan were less active on immunostimulatory activity than mixed compounds of polysaccharides. From the viewpoint of structure and activity relationships, we found several characteristic features.
Chromatography ; Cytokines ; Dextrans ; Lentinan ; Lymphocytes ; Macrophages ; Molecular Structure* ; Molecular Weight ; Nitric Oxide ; Nitrites ; Panax ; Picibanil ; Polysaccharides*

The internal-loop granular sludge bed nitrifying reactor is a new type of aerobic nitrifying equipment and has taken on a good potential for nitrification. The critical aerating flux for liquid loop and critical aerating flux for fluidization of granular sludge are two important parameters for its operation. The relationship between liquid superficial velocity in riser (U1r) and aerating flux(Ugr) was studied, the model parameters were measured by experiment, and the relational expression was established. According to the model, the critical aerating flux for liquid loop and the critical aerating flux for fluidization of granular sludge were calculated as 1.017cm/min and 2.662cm/min, respectively. The experimental data from reactor operation showed that the two calculated critical aerating fluxes near the practical values. So they could be used to direct the design and operating optimization for the internal-loop granular sludge bed nitrifying reactor.
Bacteria, Aerobic ; metabolism ; Bioreactors ; Nitrites ; metabolism ; Sewage ; chemistry ; microbiology ; Waste Disposal, Fluid ; methods

To study the enrichment regulation of anammox bacteria during the whole start-up process of anammox reaction, two reactors with addition of carries of Spherical Plastic (SP) and Bamboo Charcoal (BC) and one without carrier (CK) were used to start anammox reaction. Then FISH and q-PCR analyses for the growth of all anammox bacteria were conducted during the operational process. The results indicate that the number of anammox bacteria in all reactors increased with time during the whole start-up process, which was consistent with the removal rate of ammonium and nitrite. On day 123 of stable phase, the percent of anammox cells in the sludge of CK, SP and BC accounted for 23.3%, 32.6% and 43.7%, respectively. The number of anammox bacteria 16S rRNA gene copies was (25.64 +/- 2.76) x 10(7), (47.12 +/- 2.76) x 10(7) and (577.99 +/- 27.25) x 10(7) copies g(-1) VSS in the sludge of CK, SP and BC, respectively. Carrier addition could dramatically increase enrichment of anammox bacteria. BC addition significantly increased the anammox bacteria number in the UASB reactor which resulted in the acceleration of the anammox start-up process. In addition, the max specific growth rate and the minimum doubling time were 0.064 d(-1) and 10.8 d in BC reactor. The max specific growth rate of anammox bacteria in BC reactor was 1.78 times and 1.88 times greater than that in CK and SP reactor, respectively. Therefore, the FISH and q-PCR analyses were suitable for determining the enrichment regulation of anammox bacteria during the start-up time, while a bit of differences in results existed between the two analytical methods due to the difference in analysis targets.
Ammonia ; metabolism ; Bacteria ; growth & development ; metabolism ; Bioreactors ; Industrial Microbiology ; Nitrites ; metabolism ; Oxidation-Reduction ; Sewage ; microbiology