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PubMed2004

Community analysis of ammonia oxidizer in the oxygen-limited nitritation stage of OLAND system by DGGE of PCR amplified 16S rDNA fragments and FISH.

OLAND (oxygen limited autotrophic nitrification and denitrification) nitrogen removal system was constructed by coupling with oxygen limited nitritation stage and anaerobic ammonium oxidation stage. Ammonia oxidizer, as a kind of key bacteria in N cycle, plays an important role at the oxygen limited nitritation stage of OLAND nitrogen removal system. In this study, specific amplification of 16S rDNA fragment of ammonia oxidizer by nested PCR, separation of mixed PCR samples by denaturing gradient gel electrophoresis (DGGE), and the quantification of ammonia oxidizer by fluorescence in situ hybridization (FISH) were combined to investigate the shifts of community composition and quantity of ammonia oxidizer of the oxygen limited nitritation stage in OLAND system. It showed that the community composition of ammonia oxidizer changed drastically when dissolved oxygen was decreased gradually, and the dominant ammonia oxidizer of the steady nitrite accumulation stage were completely different from that of the early stage of oxygen limited nitritation identified by DGGE. It was concluded that the Nitrosomonas may be the dominant genus of ammonia oxidizer at the oxygen limited nitritation stage of OLAND system characterized by nested PCR-DGGE and FISH, and the percentage of Nitrosomonas was 72.5% +/- 0.8% of ammonia oxidizer at the steady nitrite accumulation stage detected by FISH.

Ammonia↗
PubMed2004

Disinfection kinetics of pathogens in physicochemical sludge treated with ammonia.

Ammonia is a disinfectant which can diffuse through the membrane of highly resistant structures like helminth ova. Thus, it can be considered an alternative disinfectant of wastewater sludge with high pathogenic content. In this study, the kinetic parameters of the Hom model were used to describe the inactivation with ammonia of faecal coliforms, Salmonella spp. and viable helminth ova. These were obtained in processes considering the addition of ammonia alone as well as for ammonia combined with an increase in temperature. The sludge was sampled from a municipal wastewater treatment plant using an APT (Advanced Primary Treatment) or CEP (Chemical Enhanced Primary) process. With 20% w/w of ammonia, 7 logs of faecal coliforms, 6 logs of Salmonella spp., and 83% of viable helminth ova were reduced in 2 hours contact time. To eliminate 100% of the helminth ova from samples having 88-132 ova/g TS it was needed to combine 20% of ammonia with 50 degrees C. The analysis of parameters k, n and m indicate higher resistance to inactivation of helminth ova compared to bacteria and a better performance of the ammonia process than lime stabilization to inactivate microorganisms. In addition, ammonia increased the agricultural value of the biosolids produced.

Ammonia↗
PubMed1990

Capillary plasma ammonia concentration in neonates receiving total parenteral nutrition. Comparison with arterial and venous concentrations.

Plasma ammonia concentration in neonates has routinely been determined using arterial or venous blood. Expected plasma ammonia values in capillary blood obtained by heelstick have not been determined. We compared ammonia levels in 20 sets of plasma from simultaneously drawn arterial, venous, and capillary blood in a group of neonates receiving total parenteral nutrition. Mean ammonia concentrations in venous (107 +/- 44) and capillary blood (112 +/- 33) were 45% and 51% higher, respectively, than corresponding arterial (74 +/- 22) values (P less than .001). Ammonia levels in blood obtained by venipuncture (Ven), however, did not correlate consistently with arterial (Art) values (r = .43; Art = 51 + 0.21 Ven; P greater than .05). In contrast, ammonia levels in capillary blood (Cap) correlated well with arterial values (r = .86; Art = 10.3 + 0.6Cap; P less than .001). Ammonia levels in neonates may be reliably interpreted using the latter regression equation when blood for analysis is obtained by a properly performed heelstick, allowing the preservation of arteries and veins, and sparing the infant from repetitive needle punctures. Ammonia levels in blood obtained by venipuncture do not adequately correlate with arterial values and therefore may be therapeutically misleading.

Ammonia↗
PubMed1990

Metabolic fate of [13N]ammonia in human and canine blood.

Nitrogen-13- ([13N]) ammonia is a widely used tracer for PET myocardial blood flow studies. Quantification of blood flow using tracer kinetic principles requires accurate determination of [13N]ammonia activity in blood. Since [13N] ammonia is rapidly metabolized, the arterial input function may be contaminated by labeled metabolites. We, therefore, characterized the 13N-labeled metabolites in blood after intravenous (i.v.) injection of 20 mCi [13N]ammonia in nine healthy volunteers. Utilizing a series of ion exchange resins, 13N-labeled compounds were separated into four groups: ammonia, neutral amino acids, acidic amino acids, and urea. Analysis of the metabolic fate of [13N]ammonia indicates that over 90% of the blood activity within the first two minutes after injection is present as [13N]ammonia. However, there is considerable contamination of the blood activity at 3-5 min by [13N]glutamine (amide) and urea, which collectively represent 18%-50% of the blood activity. Thus, correction of the arterial input function for 13N-metabolites is required to accurately quantify the arterial input function of [13N]ammonia in myocardial blood flow studies.

Adult↗
PubMed1978

Effect of lactulose on ammonia production in a fecal incubation system.

An in vitro fecal incubation system was used to demonstrate how lactulose influences ammonia metabolism in the colon. Lactulose and other fermentable substrates (glucose, mannitol, and sorbitol), pH and organic acid were varied independently so that their different effects could be determined. Fermentable substrate caused a fall in ammonia concentration during the period of fermentation. Acidification to pH 5.0 or less, with hydrochloric acid or a lactic-acetic acid mixture, significantly reduced ammonia generation, but unlike fermentable substrates, did not lower the existing ammonia concentration. The lactic-acetic acid mixture did not reduce ammonia generation significantly below that found with acidification by hydrochloric acid. The effect of lactulose in reducing ammonia concentration is attributed to its role as a bacterial substrate in either increasing bacterial assimilation of ammonia or reducing deamination of nitrogenous compounds. The effect of low pH in reducing generation of ammonia appears to be part of a general reduction in bacterial metabolism.

Ammonia↗
PubMed1989

Excitation of both slowly and rapidly adapting pulmonary stretch receptors attenuates tachypnea induced by ammonia.

To elucidate the mechanism of attenuating the ammonia-induced tachypnea, the present study examined the discharge patterns and rates of slowly adapting pulmonary stretch receptors (SARs) and rapidly adapting pulmonary stretch receptors (RARs) in relation to the change in respiration produced by ammonia inhalation in anesthetized, spontaneously breathing rabbits. Extracellular action potentials of these two receptors were recorded at the peripheral cut-end of the left vagus nerve. A prolongation of expiration following ammonia inhalation occurred during the discharge of receptors increased continuously, particularly when the level of the discharge rate during expiration reached to approximately 20-fold, and under such circumstances the respiratory response was regularly associated with gasps. On the other hand, RARs increased their activity during only inspiration; this increased activity correlated with augmentation of inspiration. Furthermore, the prolongating effect of expiration due to ammonia inhalation was not observed after surgical denervation of the remaining right vagus nerve. These results suggest that vigorous stimulation of the SAR activity induced by ammonia inhalation can elicit a prolongation of expiration possibly resulting from augmentation of the Hering-Breuer inflation reflex and that augmentation of the increased RAR activity after ammonia inhalation counteracts the Hering-Breuer inflation reflex to shorten inspiration. Therefore, it is conceivable that strong stimulation of the SAR activity after ammonia inhalation counteracts the ammonia-induced tachypnea.

Action Potentials↗
PubMed1989

Serum ammonia levels in response to glycine infusion in normal and cirrhotic rats.

Elevated serum ammonia may play a role in central nervous system derangement after transurethral resection of the prostate. Glycine used as a surgical irrigant for prostate resection produces ammonia as a by-product after liver and renal metabolism. The presence of liver dysfunction often leads to an inability to remove generated ammonia from the circulation. To determine whether the presence of cirrhosis allows significant metabolism of glycine and the resulting serum ammonia levels generated, the production of ammonia after glycine infusion was examined in normal and cirrhotic rats. Hepatic microsomal enzyme induction was produced in male Sprague-Dawley rats given sodium phenobarbital, added to the drinking water to hasten the development of cirrhosis, by increasing the toxicity of carbon tetrachloride given intragastrically to one group at weekly intervals for production of cirrhosis. A control group was maintained under similar conditions except for carbon tetrachloride dosing. The end point for production of cirrhosis was the development of ascites. Two weeks after the development of ascites in the cirrhotic rats and the discontinuation of phenobarbital in both groups, both control and cirrhotic rats were anesthetized with IP pentobarbital and glycine (1.25 g/kg; 7.5%) was given intravenously. Venous blood samples were taken at intervals up to 120 min for serum ammonia analysis. After the final serum ammonia sample, lethal pentobarbital injection was given and livers and kidneys removed for histologic analysis. Terminal body weight, glycine dose, and renal histology were not different between groups. Liver weights were greater in cirrhotic rats. Baseline serum ammonia levels were also greater int he cirrhotic rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗
PubMed1986

[Ammonia and glutamine metabolism of the intestine. The effect of lactulose and neomycin].

The present work is directed to distinguish between ammonia production by the mucosa and by the intestinal flora, as well as to evaluate the influence of neomycin and lactulose. In vitro studies using rat intestine show that mucosa cells produce ammonia alanine and glutamic acid when incubated with glutamine, whose process can be impaired by neomycin or lactulose. Since the release of the above solutes is virtually the same in germ-free rats, the influence of the bacterial flora might be negligible under the experimental conditions used. Elimination of the aerobic microorganisms results in a minute decrease of ammonia concentration in portal blood in contrast to elimination of the anaerobic flora, which leads to an excessive reduction of ammonia formation. In germ-free rats colonisation with anaerobic microorganisms results in an increment in portal ammonia concentration, whose value, however, is still below levels observed in normal animals. Colonisation with aerobic bacteria has no effect on portal ammonia concentration. Neomycin and lactulose affect ammonia production in the gut by interfering with glutamine uptake in the mucosa cell, thus the influence upon ammonia formation apparently can not be exclusively explained by alterations of the intestinal flora. Possible reasons for the considerable increase in arterial glutamine levels in normal rats are discussed.

Ammonia↗
PubMed1985

Ammonia production and amino acid metabolism by rat renal papillary epithelial cells in culture.

A significant percentage of excreted ammonium is added to tubular fluid along the medullary collecting duct. However, it is not clear whether this ammonia is produced in the cortex and delivered into the medulla or is produced directly by medullary cells. To address this issue, rat epithelial cells derived from the renal papilla were grown in continuous culture and their ability to generate ammonia was examined. When grown in Dulbecco's modified Eagle's medium with 4 mM glutamine, these cells produced ammonia at a rate of approximately 27 nmol/10(6) cells/h. When these cells were grown in minimum essential medium without glutamine, ammonia production fell to 7 nmol/10(6) cells/ h. Increasing the glutamine concentrations of minimum essential medium to 4 mM increased ammonia production to slightly greater than 30 nmol/10(6) cells/ h. Increasing the media concentration of glutamate, glycine, or asparagine resulted in no significant increase in ammoniagenesis. Analysis of media amino acid concentration revealed that glutamine was the main amino acid consumed while alanine was the predominant amino acid produced. The glutaminase activity of these cells appears to be primarily phosphate-dependent, similar to that observed in vitro in papillary tubules. Alterations of K+ or H+ ion concentration did not alter ammoniagenesis, but addition of 2.5 mM ammonium chloride significantly reduced net ammonia production. It is concluded that rat papillary epithelial cells have the intrinsic ability to utilize glutamine to generate ammonia and alanine. In vivo ammonia produced locally in the medulla may contribute to final urinary ammonium excretion.

Amino Acids↗
PubMed1984

Effect of bedding changes and room ventilation rates on blood and brain ammonia levels in normal rats and rats with portacaval shunts.

Normal rats and rats with portacaval shunts were exposed to low concentrations of atmospheric ammonia generated from decomposing urine and feces. The ammonia concentration in the atmosphere was varied by altering the effective ventilation rate, animal density in the enclosure, and bedding change frequency. Atmospheric ammonia concentrations in the animal holding areas varied inversely with the frequency of bedding change and the rate of air exchange. Significant differences were found between normal and shunted animals in blood ammonia and alkaline phosphatase; brain ammonia, glutamate, and glutamine; and body weight. However, these alterations were the same regardless of the atmospheric ammonia concentration; there were no differences within the control group or shunted group housed in the different conditions. The findings suggest that in the range of ammonia concentrations in this study (0 to 9 ppm), ammonia taken in through the respiratory tract is not accumulated in the body to any significant extent.

Air Pollutants↗
PubMedDate not supplied

Ammonia transport across hydrophobic membranes. Application to dialysate regeneration.

Removal of ammonia from a recirculating dialysate buffer in a portable hemodialysis application can be achieved by countercurrent, gas phase ammonia transfer across a hydrophobic membrane into an acid solution. Ammonia transfer fluxes as high as 0.076 mumol/sec/m2 have been achieved using a Sarns Turbo Membrane Oxygenator (Sarns-3M, Ann Arbor, MI) with a 1.9 m2 membrane surface area (0.145 mumol/sec actual rate). A simple physical model based upon ammonia desorption at the gas-dialysate buffer interface in a membrane pore, ammonia diffusion through the gas filled pore, and subsequent ammonia absorption at the gas/acid interface side of the pore quantitatively describes the experimental data. The ammonia transfer rate is most dependent upon dialysate buffer pH (higher pH promoting transfer rate) and ammonia concentration in the dialysate buffer (higher concentrations promoting transfer rate). A 500 fold improvement in transfer rate, however, will be required for clinical application.

Absorption↗
PubMed1993

Blood ammonia concentration after supramaximal treadmill running in males and females.

The purpose of this study was to investigate the difference in human blood ammonia content between the sexes and the relationship between work.lean body mass (LBM)-1 and the peak blood ammonia content following supramaximal exercise. Eight males and six females ran on a motor-driven treadmill reaching exhaustion induced in less than 70 s. Total work, heart rate (HR), blood lactate and ammonia concentrations were measured at rest, immediately after warming-up, and at 2.5, 5, 7.5, 10, 12.5, 15 min after supramaximal exercise. Total work and work.LBM-1 were significantly greater in males than in females (p < 0.01). There was a significant relationship between the peak blood ammonia content and work.LBM-1 in all of the subjects (r, 0.627: p < 0.05). Though no significant difference was found in ammonia at rest between males and females, the peak blood ammonia content after supramaximal exercise in males was significantly greater than in females (p < 0.05). These results suggest that the peak blood ammonia content relates positively to anaerobic work capacity following supramaximal exercise, and that a difference in blood ammonia content exists between the sexes.

Adult↗
PubMed1977

Ammonia production during clot retraction and its use in assay of fibrinoligase.

Clotting of recalcified plasma is followed by an increase in its ammonia content that lasts 4 to 6 h. This ammonia production closely parallels the increase in acid-insoluble fibrin, which is evidence that the ammonia results from the action of fibrinoligase. If the clot is removed, ammonia production stops. The initial velocity of ammonia production is directly proportional to the fibrinogen concentration in plasma. Thus the rate-limiting factor in normal shed blood is the fibrinogen concentration. A maximum of 6.4 +/- 1.5 (SD) molecules of ammonia are produced per molecule of fibrinogen. Determination of the total ammonia produced is the fastest direct method of estimating the extent of frbrin cross-linkage in whole plasma. A method is proposed for assaying fibrinoligase, based on the rate of ammonia production in the presence of casein as substrate. Normal values are 7.6 +/- 2.9 (SD) mumol/min per liter of plasma.

Adult↗
PubMed1991

Adaptation of hybridoma cells to higher ammonia concentration.

Using two mouse-mouse hybridoma cell lines, the response to ammonia step and serial changes was investigated in batch and continuous cultures with serum-free medium. The inhibitory effect of ammonia on cell growth depended on the cultivation mode, and differed markedly between cell lines. The cell line, 4C10B6 producing IgG monoclonal antibody against Pseudomonas, showed a high adaptation ability to ammonia. The 4C10B6 cells could grow under ammonia concentration as high as 21 mmol/l NH4Cl with a viability of 80% in the continuous culture with serial increase in ammonia concentration. Whereas, in the batch culture with ammonia step change the cell growth completely ceased at 12 mmol/l NH4Cl. The other cell line, TO-405 producing IgG monoclonal antibody against hepatitis B surface antigen, could not adapt to ammonia, and the cell growth did not occur at 9 mmol/l NH4Cl even under the ammonia serial change.

Ammonium Chloride↗
PubMed1997

The pathway of ammonia assimilation in the silkworm, Bombyx mori.

Ammonia can easily be assimilated into amino acids and used for silk-protein synthesis in the silkworm, Bombyx mori. To determine the metabolic pathway of ammonia assimilation, silkworm larvae were injected with methionine sulfoximine (MS), a specific inhibitor of glutamine synthetase (GS). Activity of GS in the fat body 2h after treatment with 400&mgr;g MS decreased to less than 10% of the control activity, whereas MS had no effect on the activity of glutamate dehydrogenase (GDH), another enzyme which could possibly be responsible for ammonia assimilation. Glutamine concentration in the hemolymph rapidly decreased after MS treatment, while the ammonia level in the hemolymph sharply increased. Glutamine concentration in the hemolymph 4h after injection decreased with increasing doses of MS, whereas ammonia concentration increased in proportion to the MS dose. MS strongly blocked the incorporation of (15)N label into silk-protein in larvae injected with (15)N ammonia acetate, while it slightly inhibited the incorporation of (15)N-amide glutamine into silk-protein. These results suggest that ammonia is mainly assimilated into glutamine via the action of GS and then converted into other amino acids for silk-protein synthesis and that GDH does not play a major role in ammonia assimilation in B. mori.

Journal Article↗
PubMed1997

Effect of ammonia on the survival of Zacco platypus (Temminck and Schlegel) at each developmental stage.

The survival rates were studied of fertilized eggs, larvae, fry, and adults of pale chub Zacco platypus (Temminck and Schlegel) exposed to various concentrations of ammonia. There was a decrease in hatching rate and an increase in deformed alevins at a concentration of 0.9 mg liter(-1) of ammonia. All alevins were deformed at a concentration of 1.6 mg liter(-1) of ammonia and no eggs hatched at a concentration of 3.1 mg liter(-1) of ammonia. No larvae survived for 84, 24 and 12 h at concentrations of 1.2, 2.0 and 4.7 mg liter(-1) of ammonia, respectively. Eighty percent of the fry died after 168 h and no fry survived for 24 h at concentrations of 1.6 and 2.1 mg liter(-1) of ammonia, respectively. Eighty percent of the adults died after 24 h and no adult survived for 12 h at concentrations of 1.0 and 1.9 mg liter(-1), respectively. Larger adults were the most susceptible to ammonia. The order of resistance to ammonia was eggs, fry, larvae, and adults.

Journal Article↗
PubMed1978

Relation of ammonia excretion adaptation to glutaminase activity in acidotic, subtotalnephrectomized rats.

The response of renal ammonia excretion to acidosis was examined in adult rats with reduced renal mass (SNX). Three days after surgical ablation of 70% of renal mass, the activity of renal phosphate-dependent glutaminase (PDG) in SNX rats was 7.7 +/- 1.5 mu moles of ammonia/100 mg of protein min or approximately 50% of the activity in normal rats (14.5 +/- 2.6 mu moles of ammonia/100 mg of protein min), but enhanced ammonia excretion per unit weight was observed in SNX rats (7.2 +/- 0.7 in control vs. 14.6 +/- 3.2 mumoles/g of kidney.hr in SNX rats). The cause (s) of the reduction in the specific activity of PDG (as well as the increase in ammonia excretion) is unknown. The PDG decrease was not due to apparent tissue damage and appeared to be a specific change as the activity of renal succinate dehydrogenase, another mitochondrial inner-membrane enzyme, did not decrease (from the control level) in SNX rats. Ammonia excretion showed no significant response to an acute acid load (ammonium chloride, 5 mmoles/kg of body wt) in SNX rats. Ammonia excretion, however, did adapt to repeated acid-loading (10 mmoles of ammonium chloride per kg of body wt per day for 3 days); ammonia excretion increased more than two-fold by third day of treatment. This adaptive response was associated with a two-fold rise in renal PDG. Administration of actinomycin D, at a dose which produced no gross toxic signs (100 microgram/kg/day i.p.) inhibited virtually all the increase in both ammonia excretion and PDG activity. The correlation of ammonia excretion and PDG adaptations in acidotic SNX rats was similar to that previously observed in infant rats.

Acidosis↗
PubMed1975

Analysis of regulatory factors for urea synthesis by isolated perfused rat liver. I. Urea synthesis with ammonia and glutamine as nitrogen sources.

Urea synthesis was studied using the isolated liver perfusion with ammonium cholride and glutamine as nitrogen sources. The rate of urea formation increases with ammonium cholorde concentration up to 5mM, and the rate remained constant in the range between 5 and 20mM of ammonium chloride as the substrate. The concentration of ammonia in the medium to support the half-maximum velocity of urea formation was 0.7mM. The rate of urea formation was stimulated by the addition of 2.5mM ornithine, and the greater part of the ornithine which was taken up into the liver was accumulated as citrulline in the presence of ammonia. A considerable accelerating effect of N-acetylglutamate on the synthetic rate was observed, but a rather high concentration of N-acetylglutamate was required in order to obtain the maximum effect possibly, because its permeability into liver cells may be limited. A marked additive effect on the rate of urea formation was observed with the combined addition of ornithine and N-acetylglutamate. The metabolic conversion of glutamine nitrogen to urea in the perfused rat liver and the effect of several compounds which stimulated urea synthesis with ammonia were further examined. The process of conversion of glutamine nitrogen to urea might be composed of the following three steps. In the first lag phase, a small amount of glutamine was removed from the medium. In the second stage, the glutamine level decreased rapidly and ammonia was accumulated in the perfusate. The third stage was a period in which glutamine concentration remained at a constant low level, and the accumulated ammonia was rapidly conversed to urea. The rate of urea formation in this third stage was found to be much higher than that with ammonia as the substrate. The maximum rate of glutamine removal was obtained at pH 7.7 of the perfusate and at a concentration of 10mM glutamine. Urea formation with glutamine was also stimulated by the addition of ornithine, malate, or N-acetylglutamate, which had accelerating effects on the urea synthesis with ammonia. This stimulation was due to an effective conversion of ammonia to urea, but no change in the rate of removal glutamine was obtained.

Ammonium Chloride↗