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Clinical Journal of the American... Oct 2016Hyperammonemia is an important cause of cerebral edema in both adults with liver failure and children with inborn errors of metabolism. There are few studies that have... (Review)
Review
Hyperammonemia is an important cause of cerebral edema in both adults with liver failure and children with inborn errors of metabolism. There are few studies that have analyzed the role of extracorporeal dialysis in reducing blood ammonia levels in the adult population. Furthermore, there are no firm guidelines about when to implement RRT, because many of the conditions that are characterized by hyperammonemia are extremely rare. In this review of existing literature on RRT, we present the body's own mechanisms for clearing ammonia as well as the dialytic properties of ammonia. We review the available literature on the use of continuous venovenous hemofiltration, peritoneal dialysis, and hemodialysis in neonates and adults with conditions characterized by hyperammonemia and discuss some of the controversies that exist over selecting one modality over another.
Topics: Adult; Ammonia; Brain Diseases; Humans; Hyperammonemia; Infant, Newborn; Renal Replacement Therapy
PubMed: 27197910
DOI: 10.2215/CJN.01320216 -
Essays in Biochemistry Aug 2023Aerobic nitrification is a key process in the global nitrogen cycle mediated by microorganisms. While nitrification has primarily been studied in near-neutral... (Review)
Review
Aerobic nitrification is a key process in the global nitrogen cycle mediated by microorganisms. While nitrification has primarily been studied in near-neutral environments, this process occurs at a wide range of pH values, spanning ecosystems from acidic soils to soda lakes. Aerobic nitrification primarily occurs through the activities of ammonia-oxidising bacteria and archaea, nitrite-oxidising bacteria, and complete ammonia-oxidising (comammox) bacteria adapted to these environments. Here, we review the literature and identify knowledge gaps on the metabolic diversity, ecological distribution, and physiological adaptations of nitrifying microorganisms in acidic and alkaline environments. We emphasise that nitrifying microorganisms depend on a suite of physiological adaptations to maintain pH homeostasis, acquire energy and carbon sources, detoxify reactive nitrogen species, and generate a membrane potential at pH extremes. We also recognize the broader implications of their activities primarily in acidic environments, with a focus on agricultural productivity and nitrous oxide emissions, as well as promising applications in treating municipal wastewater.
Topics: Nitrification; Ammonia; Ecosystem; Oxidation-Reduction; Bacteria
PubMed: 37449414
DOI: 10.1042/EBC20220194 -
Annual Review of Chemical and... Jun 2020Ammonia is a critically important industrial chemical and is largely responsible for sustaining the growing global population. To provide ammonia to underdeveloped... (Review)
Review
Ammonia is a critically important industrial chemical and is largely responsible for sustaining the growing global population. To provide ammonia to underdeveloped regions and/or regions far from industrial production hubs, modular systems have been targeted and often involve unconventional production methodologies. These novel approaches for ammonia production can tap renewable resources at smaller scales located at the point of use, while decreasing the CO footprint. Plasma-assisted catalysis and electrochemical ammonia synthesis have promise owing to their atmospheric pressure and low-temperature operation conditions and the ability to construct units at scales desired for modularization. Fundamental and applied studies are underway to assess these processes, although many unknowns remain. In this review, we discuss recent developments and opportunities for unconventional ammonia synthesis with a focus on plasma-stimulated systems.
Topics: Ammonia; Catalysis; Metal-Organic Frameworks; Nitrogen; Plasma Gases; Renewable Energy
PubMed: 32155349
DOI: 10.1146/annurev-chembioeng-092319-080240 -
Microbiology (Reading, England) Jul 2022is a marine ammonia-oxidizing archaeon with a high affinity for ammonia. It fixes carbon via a modified hydroxypropionate/hydroxybutyrate cycle and shows weak...
is a marine ammonia-oxidizing archaeon with a high affinity for ammonia. It fixes carbon via a modified hydroxypropionate/hydroxybutyrate cycle and shows weak utilization of cyanate as a supplementary energy and nitrogen source. When oxygen is depleted, produces its own oxygen, which may explain its regular occurrence in anoxic waters. Several enzymes of the ammonia oxidation and oxygen production pathways remain to be identified.
Topics: Ammonia; Archaea; Carbon Cycle; Oxidation-Reduction; Oxygen
PubMed: 35852832
DOI: 10.1099/mic.0.001207 -
Metabolic Brain Disease Apr 2017Ammonia is diffused and transported across all plasma membranes. This entails that hyperammonemia leads to an increase in ammonia in all organs and tissues. It is known... (Review)
Review
Ammonia is diffused and transported across all plasma membranes. This entails that hyperammonemia leads to an increase in ammonia in all organs and tissues. It is known that the toxic ramifications of ammonia primarily touch the brain and cause neurological impairment. However, the deleterious effects of ammonia are not specific to the brain, as the direct effect of increased ammonia (change in pH, membrane potential, metabolism) can occur in any type of cell. Therefore, in the setting of chronic liver disease where multi-organ dysfunction is common, the role of ammonia, only as neurotoxin, is challenged. This review provides insights and evidence that increased ammonia can disturb many organ and cell types and hence lead to dysfunction.
Topics: Ammonia; Animals; Brain; Brain Chemistry; Hepatic Encephalopathy; Humans; Hyperammonemia; Muscle, Skeletal
PubMed: 28012068
DOI: 10.1007/s11011-016-9938-3 -
Journal of the American Association For... Mar 2019In this review, we describe the methods and technology used to measure intracage ammonia levels; the data were derived from 38 articles published since 1970. Ammonia... (Review)
Review
In this review, we describe the methods and technology used to measure intracage ammonia levels; the data were derived from 38 articles published since 1970. Ammonia concentration is commonly used as a surrogate for assessing environmental quality inside rodent cages. Data generated from this group of publications have been used to support new husbandry practices, determine the effect of ammonia on health, and establish the effectiveness of caging systems. Consequently, the data generated from these studies have a direct effect on animal welfare and therefore should demonstrate a high level of reproducibility. Obtaining reproducible results requires a critical understanding of the methodology and the technology used to collect ammonia concentration data. This review highlights the need for consistent methodology for measuring ammonia that considers the technology used to capture the data as well as the environmental parameters that affect ammonia concentrations, to facilitate the design of future studies.
Topics: Ammonia; Animal Husbandry; Animal Welfare; Animals; Housing, Animal; Laboratory Animal Science; Ventilation
PubMed: 30704550
DOI: 10.30802/AALAS-JAALAS-18-000006 -
Chemical Reviews Jun 2020The reduction of dinitrogen to ammonia by nitrogenase reflects a complex choreography involving two component proteins, MgATP and reductant. At center stage of this... (Review)
Review
The reduction of dinitrogen to ammonia by nitrogenase reflects a complex choreography involving two component proteins, MgATP and reductant. At center stage of this process resides the active site cofactor, a complex metallocluster organized around a trigonal prismatic arrangement of iron sites surrounding an interstitial carbon. As a consequence of the choreography, electrons and protons are delivered to the active site for transfer to the bound N. While the detailed mechanism for the substrate reduction remains enigmatic, recent developments highlight the role of hydrides and the privileged role for two irons of the trigonal prism in the binding of exogenous ligands. Outstanding questions concern the precise nature of the intermediates between N and NH, and whether the cofactor undergoes significant rearrangement during turnover; resolution of these issues will require the convergence of biochemistry, structure, spectroscopy, computation, and model chemistry.
Topics: Ammonia; Crystallization; Metals, Heavy; Models, Molecular; Nitrogen; Nitrogenase; Protein Conformation
PubMed: 32538623
DOI: 10.1021/acs.chemrev.0c00067 -
The Journal of Physical Chemistry... Oct 2022Here we prove that, in addition to temperature and pressure, another important thermodynamic variable permits the exploration of the phase diagram of ammonia: the...
Here we prove that, in addition to temperature and pressure, another important thermodynamic variable permits the exploration of the phase diagram of ammonia: the electric field. By means of (path integral) molecular dynamics simulations, we predict that, upon applying intense electric fields on ammonia, the electrofreezing phenomenon occurs, leading the liquid toward a novel ferroelectric solid phase. This study proves that electric fields can generally be exploited as the access key to otherwise-unreachable regions in phase diagrams, unveiling the existence of new condensed-phase structures. Furthermore, the reported findings have manifold practical implications, from the safe storage and transportation of ammonia to the understanding of the solid structures this compound forms in planetary contexts.
Topics: Ammonia; Thermodynamics; Molecular Dynamics Simulation; Temperature; Electricity
PubMed: 36255376
DOI: 10.1021/acs.jpclett.2c02576 -
Advanced Drug Delivery Reviews Aug 2015Ammonia is a neurotoxic agent that is primarily generated in the intestine and detoxified in the liver. Toxic increases in systemic ammonia levels predominantly result... (Review)
Review
Ammonia is a neurotoxic agent that is primarily generated in the intestine and detoxified in the liver. Toxic increases in systemic ammonia levels predominantly result from an inherited or acquired impairment in hepatic detoxification and lead to potentially life-threatening neuropsychiatric symptoms. Inborn deficiencies in ammonia detoxification mainly affect the urea cycle, an endogenous metabolic removal system in the liver. Hepatic encephalopathy, on the other hand, is a hyperammonemia-related complication secondary to acquired liver function impairment. A range of therapeutic options is available to target either ammonia generation and absorption or ammonia removal. Therapies for hepatic encephalopathy decrease intestinal ammonia production and uptake. Treatments for urea cycle disorders eliminate ammoniagenic amino acids through metabolic transformation, preventing ammonia generation. Therapeutic approaches removing ammonia activate the urea cycle or the second essential endogenous ammonia detoxification system, glutamine synthesis. Recent advances in treating hyperammonemia include using synergistic combination treatments, broadening the indication of orphan drugs, and developing novel approaches to regenerate functional liver tissue. This manuscript reviews the various pharmacological treatments of hyperammonemia and focuses on biopharmaceutical and drug delivery issues.
Topics: Ammonia; Animals; Humans; Hyperammonemia; Inactivation, Metabolic
PubMed: 25895618
DOI: 10.1016/j.addr.2015.04.009 -
Chemical Research in Toxicology Aug 2020Ammonia is treated as a primary waste product of cellular metabolism and can contribute to the alteration of neurotransmission, oxidative stress, and cerebral edema and...
Ammonia is treated as a primary waste product of cellular metabolism and can contribute to the alteration of neurotransmission, oxidative stress, and cerebral edema and astrocyte swelling when its concentration in the brain is high. The objective of this study was to determine whether bioactive polyphenol baicalein had the capacity to trap ammonia and . Under conditions, baicalein rapidly reacted with ammonia to generate two monoaminated products and one diaminated product under different reaction times. These three major aminated products were purified from the reaction mixture, and their structures were characterized as 5-NH-baicalein, 6-NH-baicalein, and 5,6-di-NH-baicalein based on the analysis of their HR-MS and 1D- and 2D-NMR data. In mice, both 5-NH-baicalein and 6-NH-baicalein were detected in 24 h fecal and urine samples collected from mice treated with baicalein (200 mg/kg) through oral gavage, and 6-NH-baicalein was also detected in mouse plasma and brain samples collected at 0.5 h after baicalein treatment. Significant amounts of 6-NH-baicalein were detected in all mouse samples including feces, urine, plasma, and brain. The levels of 6-NH-baicalein in feces and urine were significantly higher than those of 5-NH-baicalein. Furthermore, the average level of 6-NH-baicalein was very close to that of baicalein (3.62 vs 3.77 ng/g) in mouse brain, suggesting it is possible that baicalein has the capacity to be absorbed rapidly into the circulation system and then cross the blood-brain barrier into the brain to detoxify ammonia in the blood and brain. In conclusion, this study confirmed that baicalein, a flavonoid with a -trihydroxyl structure on the A-ring, has the potential to detoxify ammonia and treat ammonia-associated chronic diseases.
Topics: Ammonia; Animals; Flavanones; Male; Mice; Molecular Structure
PubMed: 32618193
DOI: 10.1021/acs.chemrestox.0c00205