Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “AMMONIA AND AMMONIUM COMPOUNDS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed2001

Deactivation of the pulmonary surfactant dynamics by toxic aerosols and gases.

Interactions between selected toxic aerosols and gases occurring in the air at the workplace and the pulmonary surfactant (PS) have been studied with two physicochemical techniques in vitro. The Pulsating Bubble Surfactometer (PBS) and the Langmuir-Wilhelmy Balance (LWB) have been used for measurements of dynamic interfacial properties of the PS material after its contact with several gases (sulfur dioxide, nitrogen oxides, ozone, ammonia) and liquids (sulfuric, nitric and hydrochloric acids and ammonium hydroxide), which can be brought into the alveoli with the inhaled air. Surface tension-area relationships for the interface oscillations have been analyzed using qualitative criteria of normalized hysteresis area (HA(N)) and minimum surface tension (sigma(min)). It was demonstrated that, for each analyzed compound, inactivation of the surfactant occurs, but the critical concentrations and doses are compound specific, which suggests the toxic potential of the investigated substances with respect to PS. Possible mechanisms of the interactions between the investigated substances and the surfactant components are discussed. Degradation of the PS dynamical interfacial properties (HA(N) and sigma(min)), important from the physiological viewpoint, observed in our in vitro experiments, suggests a possibility of adverse health effect in the case of a chronic inhalation of toxic gases and aerosols, even at low concentration or after a short exposure to strongly contaminated air. It results in a slowdown of the pulmonary clearance rate and increase of the lung burden for both considered cases.

Aerosols↗
PubMed1970

The effect of uncomplicated potassium depletion on urine acidification.

Studies were performed on normal human subjects to determine the effects of potassium depletion on urine acidification. Depletion was induced by ingestion of a low potassium diet either alone or in combination with a potassium-binding resin, and the response of each subject to an acute ammonium chloride load in the potassium-depleted state was compared to his normal response. Urine pH was significantly higher during potassium deficiency if sufficient potassium depletion had been induced. No differences in blood acid-base parameters, urinary flow rate, or urinary fixed buffer excretion rate were found to account for this change; however, the increase in urine pH was accompanied by a concomitant increase in net acid and ammonium excretion. It is proposed that these changes during potassium depletion reflect an increase in ammonia diffusion into the urine, presumably as a result of increased renal ammonia production. In addition, it is speculated that changes in ammonia metabolism may be a physiologic control mechanism for potassium conservation.

Acid-Base Equilibrium↗
PubMed1996

Influence of four diets on uric acid metabolism and endogenous acid production in healthy beagles.

OBJECTIVE: To evaluate the influence of 3 diets used to dissolve or prevent ammonium urate uroliths in dogs, and a diet formulated for growth, on 24-hour excretions of uric acid, ammonia, net acid, titratable acid, bicarbonate, and creatinine; 24-hour urine volumes; pH values of 24-hour urine samples; plasma uric acid concentration; serum creatinine concentration; and endogenous creatinine clearance values. DESIGN: Randomized block. ANIMALS: Six reproductively intact female Beagles, 3.9 to 4.2 years old, weighing 8.5 to 11.1 kg. PROCEDURES: Four diets were evaluated for their ability to dissolve magnesium ammonium phosphate hexahydrate (struvite) uroliths (diet S); to minimize uric acid excretion (diet U); to minimize clinical signs associated with renal failure (diet K); and to promote growth in pups (diet P). Each diet was fed for 14 days; then 24-hour urine samples were collected. An adult maintenance diet was fed during a 7-day washout period. RESULTS: Consumption of diet U was associated with lowest plasma uric acid concentration, lowest 24-hour urinary uric acid, ammonia, titratable acid, and net acid excretions, lowest endogenous creatinine clearance values, highest 24-hour urinary bicarbonate excretion and urine pH values, and highest 24-hour urine volumes. Consumption of diet P was associated with opposite results; results of consumption of diets S and K were intermediate between those for diets U and P. CONCLUSION: Consumption of diet U by healthy Beagles is associated with reduced magnitude of urinary excretion of uric acid and ammonia, with alkaluria, and with polyuria, which may be beneficial in the management of ammonium urate uroliths in dogs. CLINICAL RELEVANCE: Results support use of diet U for management of ammonium urate urolithiasis in dogs.

Ammonia↗
PubMed1984

Oxidation of ammonia and hydroxylamine to nitrate in the rat.

We have demonstrated that ammonia is oxidized to nitrate in the rat. Male Sprague-Dawley rats gavaged with 1 000 mumol 15N-ammonium chloride each day for five days were found to excrete low, but significant, amounts of excess 15N-nitrate in their urines on the five days of treatment and on the five subsequent days. We recovered a total of 0.28 +/- 0.03 mumol excess 15N-nitrate (mean +/- SE) per rat, which indicates that ammonia is converted to nitrate with a yield of about 0.0080%. 15N-Hydroxylamine was oxidized in the rat to 15N-nitrate with a yield of 4.7%, but oxidation of 15N-labeled glycine and L-glutamic acid to 15N-nitrate could not be detected. These results suggest that hydroxylamine, but not glycine or L-glutamic acid, may be an intermediate in the ammonia oxidation process. The injection of rats with Arochlor 1254 failed to stimulate nitrate synthesis, which indicates that the cytochrome P-450 drug metabolizing system is probably not involved in ammonia oxidation. Carbon tetrachloride, which causes hepatic lipid peroxidation, produced a small, but significant, increase in nitrate synthesis. Our results are consistent with the hypothesis that ammonia is oxidized in vivo by a non-enzymatic process involving reactive oxygen species. We estimate that a 215 g rat produces 3.0 mumol of nitrate per day by this process. The significance of our results to the problem of endogenous N-nitroso compound formation in man is discussed.

Ammonium Chloride↗
PubMed2002

Bacteriocin-like activity of Butyrivibrio fibrisolvens JL5 and its effect on other ruminal bacteria and ammonia production.

When ruminal bacteria from a cow fed hay were serially diluted into an anaerobic medium that had only peptides and amino acids as energy sources, little growth or ammonia production was detected at dilutions greater than 10(-6). The 10(-8) and 10(-9) dilutions contained bacteria that fermented carbohydrates, and some of these bacteria inhibited Clostridium sticklandii SR, an obligate amino acid-fermenting bacterium. Phylogenetic analysis indicated that the most active isolate (JL5) was closely related to Butyrivibrio fibrisolvens B835. Strain JL5 inhibited B. fibrisolvens 49 and a variety of other gram-positive organisms, but it had little effect on most gram-negative ruminal bacteria. Strain JL5 did not produce a bacteriocin-like inhibitory substance (BLIS) until it reached the late log or stationary phase. The JL5 BLIS did not cause the lysis of B. fibrisolvens 49, but the intracellular potassium level, the ATP level, the electrical potential, and the viability decreased rapidly. The JL5 BLIS also caused marked decreases in the viability and cellular potassium level of C. sticklandii SR. The membrane potential and intracellular ATP level also declined. The BLIS was degraded very slowly by pronase E, but it could be precipitated with 60% ammonium sulfate and dialyzed (3,500-Da cutoff). The BLIS could be separated from other peptides by polyacrylamide gel electrophoresis, and C. sticklandii SR overlays indicated that the molecular size of this compound was approximately 3,600 Da. Based on these results, it appeared that the JL5 BLIS was a pore-forming peptide. Because carbohydrate-fermenting ruminal bacteria could inhibit the growth of obligate amino acid-fermenting bacteria, BLIS may play a role in regulating ammonia production in vivo.

Amino Acids↗
PubMed1987

Modulation of nitrate uptake in Anacystis nidulans by the balance between ammonium assimilation and CO2 fixation.

Gradual inhibition of ammonium assimilation in Anacystis nidulans cells by increasing concentrations of 5-hydroxylysine resulted in a progressive enhancement of nitrate uptake. For 5-hydroxylysine-treated cells, the magnitude of the inhibition of nitrate uptake promoted by added ammonium was dependent on the ammonium assimilation capacity. In cells with a moderate ammonium assimilation activity, acceleration of CO2 fixation induced by bicarbonate addition antagonized the negative effect of ammonium, allowing full nitrate uptake activity. The results support the contention that nitrate utilization is under the feed-back control exerted by products of its own assimilation via ammonium, the inhibitory effect being potentiated by ammonium addition and alleviated by enhanced CO2 fixation. Results of amino acid analysis in cells exhibiting different capacities to utilize nitrate speak against these compounds as direct effectors of nitrate uptake.

Amino Acids↗
PubMed2006

Different transport mechanisms in plant and human AMT/Rh-type ammonium transporters.

The conserved family of AMT/Rh proteins facilitates ammonium transport across animal, plant, and microbial membranes. A bacterial homologue, AmtB, forms a channel-like structure and appears to function as an NH3 gas channel. To evaluate the function of eukaryotic homologues, the human RhCG glycoprotein and the tomato plant ammonium transporter LeAMT1;2 were expressed and compared in Xenopus oocytes and yeast. RhCG mediated the electroneutral transport of methylammonium (MeA), which saturated with Km = 3.8 mM at pHo 7.5. Uptake was strongly favored by increasing the pHo and was inhibited by ammonium. Ammonium induced rapid cytosolic alkalinization in RhCG-expressing oocytes. Additionally, RhCG expression was associated with an alkali-cation conductance, which was not significantly permeable to NH4+ and was apparently uncoupled from the ammonium transport. In contrast, expression of the homologous LeAMT1;2 induced pHo-independent MeA+ uptake and specific NH4+ and MeA+ currents that were distinct from endogenous currents. The different mechanisms of transport, including the RhCG-associated alkali-cation conductance, were verified by heterologous expression in appropriate yeast strains. Thus, homologous AMT/Rh-type proteins function in a distinct manner; while LeAMT1;2 carries specifically NH4+, or cotransports NH3/H+, RhCG mediates electroneutral NH3 transport.

Ammonia↗
PubMed1974

Intracellular pH of snail neurones measured with a new pH-sensitive glass mirco-electrode.

1. The construction and properties of a new design of pH-sensitive micro-electrode are described. The electrodes are very durable, and have a recessed configuration so that only the extreme tip, which can be as small as 1 mum in diameter, needs to enter the cell.2. The average intracellular pH in thirty-two snail neurones was 7.4. This was not in accord with a passive distribution of H(+) ions across the cell membrane.3. Changing membrane potential or external pH had only slow effects on internal pH.4. Removing external K had no effect, and removing external Na had only slow and variable effects on intracellular pH.5. Anoxia, azide and DNP all caused a slow fall in internal pH.6. External CO(2) caused large and rapid decreases in internal pH, which external bicarbonate appeared to offset slowly. Injected bicarbonate increased internal pH.7. The size of the pH changes caused by CO(2) suggested a minimum intracellular buffering power of 25 m-equiv H(+)/unit pH per l., equivalent to that of 150 mM Tris maleate, pH 7.4.8. External ammonia caused a large and rapid increase in internal pH, while the injection of ammonium ions had the opposite effect.

Ammonia↗
PubMed2004

Adaptative increase of ornithine production and decrease of ammonia metabolism in rat colonocytes after hyperproteic diet ingestion.

Chronic high-protein consumption leads to increased concentrations of NH(4)(+)/NH(3) in the colon lumen. We asked whether this increase has consequences on colonic epithelial cell metabolism. Rats were fed isocaloric diets containing 20 (P20) or 58% (P58) casein as the protein source for 7 days. NH(4)(+)/NH(3) concentration in the colonic lumen and in the colonic vein blood as well as ammonia metabolism by isolated surface colonic epithelial cells was determined. After 2 days of consumption of the P58 diet, marked increases of luminal and colonic vein blood NH(4)(+)/NH(3) concentrations were recorded when compared with the values obtained in the P20 group. Colonocytes recovered from the P58 group were characterized at that time and thereafter by an increased capacity for l-ornithine and urea production through arginase (P < 0.05). l-Ornithine was mostly used in the presence of NH(4)Cl for the synthesis of the metabolic end product l-citrulline. After 7 days of the P58 diet consumption, however, the ammonia metabolism into l-citrulline was found lower (P < 0.01) when compared with the values measured in the colonocytes recovered from the P20 group despite any decrease in the related enzymatic activities (i.e., carbamoyl-phosphate synthetase I and ornithine carbamoyl transferase). This decrease was found to coincide with a return of blood NH(4)(+)/NH(3) concentration in colonic portal blood to values close to the one recorded in the P20 group. In response to increased NH(4)(+)/NH(3) concentration in the colon, the increased capacity of the colonocytes to synthesize l-ornithine is likely to correspond to an elevated l-ornithine requirement for the elimination of excessive blood ammonia in the liver urea cycle. Moreover, in the presence of NH(4)Cl, colonocytes diminished their synthesis capacity of l-citrulline from l-ornithine, allowing a lower cellular utilization of this latter amino acid. These results are discussed in relationship with an adaptative process that would be related to both interorgan metabolism and to the role of the colonic epithelium as a first line of defense toward luminal NH(4)(+)/NH(3) concentrations.

Adaptation, Physiological↗
PubMed2003

[Synthesis of dicarboxylic acid monoamides].

The pharmaceutical and biological importance of the amide moiety is briefly surveyed. Relationships between the electron density and chemical reactivity of the amide site are shortly described. Synthetic methods for the selective formation of monoamino-dicarboxylic acid alpha and beta monoamides are summarised. The three major selective synthesis routes for the preparation of monoamides are introduced. The first class of synthetic methods consists of non selective formation of a- and b-esters, followed by their separation on the basis of different solubilities. Amidation of these esters results in the alpha- or beta-amides respectively. The second class of the reactions utilises the orientating capacity of the amino (ammonium) site, producing first various cyclic anhydrides, lactames, lactones, which are then decomposed in hydrolytic, aminolytic, etc. reactions, resulting selectively in the alpha- or beta-amides or esters. Reactants in the third class of the reactions are dicarboxylic acids with carbon-carbon pi-bonds, and ammonia (or alkyl-amine) which form the appropriate compound in addition reactions. Reactivities and selectivities are interpreted in terms of inductive effects, acidity differences and electronic effects of the various protecting groups. Some important analytical properties of monoamino-dicarboxylic acids and their monoamides are compiled.

Amides↗
PubMed1980

[Effect of carbon and nitrogen sources on the deoxyribonuclease activity of actinomycetes (author's transl)].

The amount of the deoxyribonucleases produced by several Actinomyces species in a fluid medium varies considerably, depending on the type of the carbon and nitrogen sources added to the medium. Starch effects the enzyme biosynthesis most favourably of all tested carbon sources. The nitrates are more suitable as nitrogen sources than the ammonia compounds. Highest biosynthesis of deoxyribonucleases is observed on media containing organic nitrogen. Nutrient medium of optimum content may be found for each producer, ensuring maximum biosynthesis of deoxyribonucleases.

Actinomyces↗
PubMed2001

Influence of nutrition on acid-base balance--metabolic aspects.

BACKGROUND: Nutrition has long been known to strongly influence acid-base balance. Recently, we have shown that it is possible to appropriately estimate the renal net acid excretion (NAE) of healthy subjects from the composition of their diets. AIM OF THE STUDY: 1) To briefly present a physiologically based calculation model that allows a reasonable estimation of the analytically determined urinary NAE, 2) to summarize the underlying metabolic mechanisms and 3) to study the specific effect of protein on ammoniagenesis which may counteract, to a small degree, the primary acid load-increasing potential of protein. METHODS: The calculation model and the algorithm for predicting the dietary acid load are summarized, major metabolic (and intestinal) pathways of acid and base equivalents are explained, and urinary excretion rates of ammonium and NAE were specifically examined with special regard to the respective protein intake levels. For the latter examinations, data from diet experiments in adults and epidemiological data from children (protein intake; NAE, pH, and ammonium excretion in 24-h urine samples) were analyzed. RESULTS: The paper shows that the diet-induced generation of acidity and alkalinity is not only determined by the metabolism (oxidation) of sulfur-containing amino acids and organic acid anions of alkali salts, respectively. The intestine is also directly involved in the generation of food-derived acid or alkali loads which is due to the considerably different intestinal absorption rates of relevant food components, i. e., protein and minerals. Further analyses of the interrelation between diet and acid-base status revealed that increasing protein intake (despite its potential to increase NAE) also significantly improves the capacity for renal net acid excretion by stimulating urinary ammonium excretion. CONCLUSION: An adequate concept to estimate renal NAE and potential renal acid loads from dietary intakes must consider the specific bioavailability of the individual nutrients. Furthermore, an increased protein intake does not necessarily result in an accordingly increased use of endogenous acid excretion capacity for two reasons: 1) additional alkali loads in an appropriately composed diet can compensate for the protein-related raised acid production and 2) protein itself moderately improves the renal capacity to excrete net acid by increasing the endogenous supply of ammonia which is the major urinary hydrogen ion acceptor.

Acid-Base Equilibrium↗
PubMed2006

Electrochemical conversion characteristics of ammonia to nitrogen.

In order to evaluate the electrolytic decomposition characteristics of ammonia to nitrogen, this work has studied several experimental variables of electrolytic ammonia decomposition. The effects of the pH and the chloride ion in the solution, kinds of anodes such as IrO(2,) RuO(2), and Pt on the electrolytic decomposition of ammonia were compared, and the existence of a membrane equipped in the cell, the changes of the current density, the initial ammonia concentration, and so on were investigated for the decomposition. The performances of the electrode were totally in the order of RuO(2) approximately IrO(2) > Pt in both the acid and alkali conditions. The ammonia decomposition was the highest at a current density of 80 mA/cm(2), over which it decreased, because the adsorption of the ammonia at the electrode surface was hindered by the hydroxyl ions in the solution. The ammonia decomposition yield increased with the concentration of the chloride ion in the solution. However, the increment rate became much lesser over 10 g/l of the chloride ion. The RuO(2) electrode among the tested anodes generated the most OH radicals which could oxidize the ammonium ion at pH 7.

Ammonia↗
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↗
PubMed1985

Infusion of branched-chain amino acids and ammonium salts in rats with portacaval shunts.

During infusion into rats with a portacaval shunt of either ammonium (NH4+) salts alone or NH4+ salts combined with the three branched-chain amino acids (BCAAs) in equimolar quantities, we assessed neurologic function and measured plasma and brain ammonia and amino acid levels and the brain content of amine neurotransmitters and their metabolites. Survival was lengthened and neurologic function was preserved longer in rats receiving BCAAs. Infusion of BCAAs resulted in lower plasma and brain ammonia concentrations compared with rats receiving NH4+ salts alone. Plasma glutamine and alanine levels were higher in rats receiving BCAAs, suggesting increased ammonia detoxification. Loss of neurologic function, regardless of which solution was infused, eventually occurred and corresponded with decreased brain norepinephrine and increased brain alanine levels. These results suggest that BCAAs can protect against hyperammonemia by stimulating the peripheral detoxification of ammonia.

Amino Acids, Branched-Chain↗
PubMed2004

High-rate nitrification at low pH in suspended- and attached-biomass reactors.

This article reports on high-rate nitrification at low pH in biofilm and suspended-biomass reactors by known chemolithotrophic bacteria. In the biofilm reactor, at low pH (4.3 +/- 0.1) and low bulk ammonium concentrations (9.3 +/- 3.3 mg.liter(-1)), a very high nitrification rate of 5.6 g of N oxidized.liter(-1).day(-1) was achieved. The specific nitrification rate (0.55 g of N.g of biomass(-1).day(-1)) was similar to values reported for nitrifying reactors at optimal pH. In the suspended-biomass reactor, the average pH was significantly lower than that in the biofilm reactor (pH 3.8 +/- 0.3), and values as low as pH 3.2 were found. In addition, measurements in the suspended-biomass reactor, using isotope-labeled ammonium (15N), showed that in spite of the very low pH, biomass growth occurred with a yield of 0.1 g of biomass.g of N oxidized(-1). Fluorescence in situ hybridization using existing rRNA-targeted oligonucleotide probes showed that the nitrifying bacteria were from the monophyletic genus Nitrosomonas, suggesting that autotrophic nitrification at low pH is more widespread than previously thought. The results presented in this paper clearly show that autotrophic nitrifying bacteria have the ability to nitrify at a high rate at low pH and in the presence of only a negligible free ammonia concentration, suggesting the presence of an efficient ammonium uptake system and the means to cope with low pH.

Bacteria↗
PubMed1991

In vitro reactivation of in vivo ammonium-inactivated glutamine synthetase from Synechocystis sp. PCC 6803.

Glutamine synthetase from Synechocystis sp. strain PCC 6803 is inactivated by ammonium addition to cells growing with nitrate as the nitrogen source. The enzyme can be reactivated in vitro by different methods such as alkaline phosphatase treatment, but not phosphodiesterase, by raising the pH of the crude extract to values higher than 8, by increasing the ionic strength of the cell-free extract, or by preincubation with organic solvents, such as 2-propanol and ethanol. These results suggest that the loss of glutamine synthetase activity promoted by ammonium involves the non-covalent binding of a phosphorylated compound to the enzyme and support previous results that rule out the existence of an adenylylation/deadenylylation system functioning in the regulation of cyanobacterial glutamine synthetase.

Alkaline Phosphatase↗