Microcalorimetric measurement of reversible metabolic suppression induced by anoxia in isolated hepatocytes
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The metabolic suppression due to anoxia in hepatocytes from the anoxia-tolerant turtle Chrysemys picta bellii was measured directly using microcalorimetric techniques. The normoxic heat flux from hepatocytes in suspension (25 degrees C) was 1.08 +/- 0.08 mW/g cells and decreased by 76% to 0.26 +/- 0.03 mW/g cells in response to anoxic incubation. After an acute decrease in temperature (to 10 degrees C) anoxic heat flux dropped by 96% relative to the normoxic control at 25 degrees C. The relative decrease in heat flux at both temperatures was similar, 76% at 25 degrees C and 68% at 10 degrees C. From the caloric equivalent of glycogen fermentation to lactate the heat flux from lactate production was calculated to be -93 microW/g cells (25 degrees C), and this accounted for 36% of the anoxic heat flux. When the enthalpy change associated with the release of free glucose (from glycogen breakdown) is considered, an additional 6% of the anoxic heat flux can be accounted for. Therefore, a portion of the anoxic heat flux is unaccounted for (58%), resulting in an “exothermic gap.” This differs from the normoxically incubated hepatocytes where the indirect calorimetric measurement of heat flux (hepatocyte O2 consumption) could fully account for the calorimetrically measured heat flux. When normoxic hepatocytes were inhibited with cyanide, a rapid suppression in heat flux was observed. Because rapid reequilibration to a lower, cyanide-induced steady state occurred in < 15 min, it is also assumed that there is no short-term Pasteur effect in this tissue.(ABSTRACT TRUNCATED AT 250 WORDS)Continuous laboratory experiments have confirmed that the construction of the USSB reactor was suitable for the combination of several biological wastewater treatment processes and that both anaerobic and denitrifying anoxic granules could be cultivated inside a compact reactor. The anoxic granules were transformed from the anaerobic granules after the shift from anaerobic to anoxic conditions in the upper compartments of the USSB reactor. The denitrification in such a system can be very intensive and efficient because of the high concentration of the sludge in anoxic compartments, and the high activity of the sludge due to a high and stable temperature. The denitrification rate of 62 mg N/l.h (at 35 degrees C) was achieved in spite of COD-limited conditions in the anoxic compartment of the USSB reactor. Maximum specific activity of anoxic granules 47 mg N/g VSS.h (at 35 degrees C, with glucose as substrate) was found in batch tests. The anoxic granules originating from the anaerobic granules have still demonstrated a significant methanogenic activity comparable with the anaerobic granules.
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KANO, E., FURUKAWA, M., KANEKO, I., YOSHIKAWA, S., TSUBOUCHI, S., KONDO, T. and YAMAGATA, K. Device of Anoxic Chamber System and Repair of Potentially Lethal Damage of Anoxic Cells in Vitro. Tohoku J. exp. Med., 1986, 148 (1), 1-13-In order to study radiation responses of anoxic plateau phase cells in vitro, an air-tight anoxic chamber was devised in which Chinese hamster V-79 or Swiss mouse NIH3T3 cells were deoxygenated by replacing the air with saturatedly humidified N2 gas. The cells as adhered on the culture plate, which was contained in the anoxic chamber, were x-irradiated. The deoxygenated condition in the anoxic chamber was maintained as long as necessary. Oxygen enhancement ratio obtained by the anoxic chamber was about 2.6. Repair of potentially lethal damage of the anoxic plateau phase cells was observed to the same extent of that of the oxic cells.
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Decades of conflicting results have fueled a debate about how O 2 affects organic matter (OM) degradation and carbon cycling. In a laboratory study, using both OM taken directly from a humic lake and chemically isolated fulvic acid, we monitored the mineralization of dissolved OM in freshwater under purely oxic and anoxic conditions, under oxic then anoxic conditions, and under anoxic then oxic conditions, for 426 d. Between 5% and 24% of the initial OM was mineralized, with most extensive mineralization occurring under purely oxic and anoxic—oxic conditions. A sequential change in the O 2 regime did not result in greater overall degradation, but initially anoxic conditions favored subsequent oxic mineralization. A substantially greater fraction of the OM was degraded than in previous shorter studies, with as much as 50% of the total OM degradation occurring after 147 d into the experiment. Three fractions of the degradable OM were identified: OM degraded only under oxic conditions (68–78%), OM degraded more rapidly under anoxic conditions than under oxic conditions (16–18%), and OM degraded at equal rates under both oxic and anoxic conditions (6–14%). The degradation patterns of natural dissolved OM from a humic lake and chemically isolated fulvic acid were very similar, which indicates a similar level of bioavailability. The difference between anoxic and oxic degradation was greater in our long‐term studies than in previous short‐term experiments, which indicates that the oxic and anoxic degradation potentials vary with increasing overall OM recalcitrance and that similar oxic and anoxic degradation rates can be expected in short‐term experiments in which <30% of the long‐term degradable OM is allowed to decompose.
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Abstract A laboratory‐scale anaerobic/anoxic/oxic reactor system was used to treat synthetic brewery wastewater for 1 year. The objectives were to enhance denitrifying phosphorus removal, improve biological nutrient removal and reduce operating costs. Three operational strategies were tested: (1) controlling nitrate recirculation to stimulate the growth of denitrifying phosphate‐accumulating organisms; (2) adjusting the volume ratio of the anaerobic/anoxic/oxic zones to enhance anoxic P uptake; (3) bypassing a part of the influent flow into the anoxic zone to maximise anoxic P uptake and denitrification. The results showed that not only was anoxic P uptake enhanced but also energy consumption for aeration could be reduced when the anoxic effluent NO 3 − ‐N concentration was controlled between 1 and 3 mg L −1 . The optimal volume ratio of the anaerobic/anoxic/aerobic zones in this system was found to be 1:1:2. The optimal bypass flow ratio was 0.32. The results indicated that the optimal strategies could improve treatment performance and reduce operational costs, but there was still a challenge to treat wastewater with low C/N ratio. Copyright © 2006 Society of Chemical Industry
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Objective:To investigate the long-term effects of low dosage La(NO3)3 on insulin and blood glucose in serum and hepatocyte glycogen in rat.Methods:Levels of Insulin and blood glucose and hepatocyte glycogen in rat were measured by radiommunoassay and microscopy image analysis system after administrated with La(NO3)3(10.0 mg/kg、 2.0 mg/kg、 0.2 mg/kg、 0.1 mg/kg)for six and seven months.Results:Having taken La(NO3)3 for 6 months,insulin levels in the 10.0 mg/kg group were reduced,blood glucose and hepatocyte glycogen levels in the 10.0 mg/kg group were increased,both in the sera of female and male rats;insulin levels、 blood glucose levels and hepatocyte glycogen levels in the 0.1 mg/kg、 0.2 mg/kg、 2.0mg/kg group,low dose treated groups was increased and later was reduced in the sera of the male.After fed by normal chow without La(NO3)3 for one month,the levels of insulin、 blood glucose and hepatocyte glycogen returned to normal again.Conclusion:A long-term low dosage La(NO3)3 could change insulin、 blood glucose and hepatocyte glycogen levels.Insulin、 blood glucose and hepatocyte glycogen levels could back to normal levels after a short time of feeding without La.La(NO3)3.In concentration of 0.2 mg/kg and 0.1 mg/kg,it had the capacity to increase the levels of insulin、 blood glucose and hepatocyte glycogen.
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The study focuses on decarbonization and nitrification theory and parameters of Anoxic-Aerobic BAF techniques.The impact of COD,NH3-N and TN removal performance were established considering hydraulic loading.The test result indicated that anoxic section of Anoxic-Aerobic BAF was vital for COD,NH3-N and TN removal.In order to obtain the best processing effect,the anoxic section must maintain the height scope of 500-600mm.When the Anoxic-Aerobic BAF hydraulic loading was 2-3 m/h,the ratio of the anoxic section volume to the aerobic one was 1:3,and the COD,NH3-N and TN have the best removal effect.The conclusion is that the increase of the hydraulic loading of Anoxic-Aerobic BAF leads more dissolved oxygen to anoxic section with the backflow intermixture and enhances the water perturbation in filters,strengthens reaerationon in the column,destroys the anoxic section filters in the column.It is disadvantageous to the denitrification and the total nitrogen removal.
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Anoxic zones in biological nitrogen removal systems are typically open to the atmosphere and receive oxygen from the atmosphere and the recirculation flow from the aerobic zone. This raises the question of how such oxygen input might influence the stability and inducibility of the enzyme systems involved in biodegradation of aromatic compounds. To investigate this, various amounts of oxygen were added to mixed culture denitrifying chemostats receiving benzoate at 667 mg/h as chemical oxygen demand (COD), and the stability and inducibility of the culture's benzoate biodegradative capability (BBC) were tested in aerobic and anoxic fed-batch reactors (FBRs). Cultures from chemostats receiving oxygen at 0, 33, 133, 266, and 466 mg O2/h lost almost all of their anoxic BBC within one hour after being transferred to an aerobic FBR and the first three cultures did not recover it upon being returned to anoxic conditions. The last two cultures recovered their anoxic BBC between 9 and 16 h during the 16 h aerobic exposure period that preceded their return to anoxic conditions and continued to increase their anoxic BBC as they were retained under anoxic conditions. In contrast, the culture from a chemostat receiving oxygen at 67 mg O2/h retained its anoxic BBC longer, recovered it within 3 h after its return to anoxic conditions, and increased it linearly thereafter. None of the cultures developed any aerobic BBC during the 16 h aerobic exposure period in FBRs. The results suggest that higher oxygen inputs into anoxic reactors helped the mixed microbial cultures recover and/or induced anoxic BBC more easily when they were exposed to alternating aerobic/anoxic environments. The exceptional behavior of the culture from the chemostat receiving oxygen at a rate of 67 mg O2/h may have been caused by the presence of a protective mechanism against the toxic forms of oxygen.
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The nitrate nitrogen in the sludge can be removed by first anoxic district of modified A2O technology.The bio-denitrification in first anoxic district was an important way for total nitrogen(TN) removal in system.Based on modified A2O technology in Kunshan astewater Treatment Plant(WWTP),the ways and quantity of TN removal were analyzed by quantitative methods.TN removal was the most happened in the first anoxic district and traditional anoxic district,where contribution rate of NO-3 were 51% and 42%,respectively.The average quantity of NO-3 in the first anoxic district was 132kg/d,correspondingly the rate of removal was up to 81.5%.However,the rate of mixed liquid recycles was excess for bio-denitrification in the traditional anoxic district.The rate of mixed liquid recycles was suggested reducing to 150%.As an important way for TN removal in preposing denitrification,the TN removal relationship between traditional anoxic and first anoxic should be balanced in order to meet TN discharge standard.
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