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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 -
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 Occupational Health Jan 2020With the increasing demand for the detection of occupational hazard factors in workplaces, the national standard determination method for ammonia (sampling with... (Review)
Review
OBJECTIVES
With the increasing demand for the detection of occupational hazard factors in workplaces, the national standard determination method for ammonia (sampling with absorbing solution-analysis with Nessler reagent spectrophotometry) in the air of workplace presents many drawbacks during application in China. This review summarized the improvement and the alternate methods of the current sampling and analysis procedures for ammonia, aiming to provide reference to establish an appropriate method for the determination of ammonia in workplace air.
METHODS
Scientific publications in English and Chinese and the standard methods of the Deutsche Forschungsgemeinschaft (DFG) in Germany, the National Institute for Occupational Safety and Health (NIOSH) and Occupational Safety and Health Administration (OSHA) in the United States, and Ministry of Health in China for airborne ammonia collection and analysis in the workplace were reviewed.
RESULTS
The measures to improve the current sampling and analysis procedures for ammonia in China were firstly summarized. For sampling, the decrease of absorbing solution concentration and the methanesulfonic acid solution as the alternate sampling solution were suggested. For analysis, the anti-interference measures and the optimum reaction condition between ammonia and Nessler reagent were discussed. The alternate methods including sampling conducted using solid sorbent tubes and analysis performed by ion chromatography were then considered for the determination of ammonia.
CONCLUSIONS
The methods-sampling with acid-treated solid sorbent tubes and analysis with ion chromatography-were more suitable for the determination of ammonia in workplace air. However, some details about ammonia sampling and analysis still need further investigation.
Topics: Air Pollutants, Occupational; Ammonia; China; Environmental Monitoring; Occupational Exposure; Reference Standards; Workplace
PubMed: 31763758
DOI: 10.1002/1348-9585.12100 -
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 -
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 -
Comprehensive Physiology Jan 2013Renal ammonia metabolism and transport mediates a central role in acid-base homeostasis. In contrast to most renal solutes, the majority of renal ammonia excretion... (Review)
Review
Renal ammonia metabolism and transport mediates a central role in acid-base homeostasis. In contrast to most renal solutes, the majority of renal ammonia excretion derives from intrarenal production, not from glomerular filtration. Renal ammoniagenesis predominantly results from glutamine metabolism, which produces 2 NH4(+) and 2 HCO3(-) for each glutamine metabolized. The proximal tubule is the primary site for ammoniagenesis, but there is evidence for ammoniagenesis by most renal epithelial cells. Ammonia produced in the kidney is either excreted into the urine or returned to the systemic circulation through the renal veins. Ammonia excreted in the urine promotes acid excretion; ammonia returned to the systemic circulation is metabolized in the liver in a HCO3(-)-consuming process, resulting in no net benefit to acid-base homeostasis. Highly regulated ammonia transport by renal epithelial cells determines the proportion of ammonia excreted in the urine versus returned to the systemic circulation. The traditional paradigm of ammonia transport involving passive NH3 diffusion, protonation in the lumen and NH4(+) trapping due to an inability to cross plasma membranes is being replaced by the recognition of limited plasma membrane NH3 permeability in combination with the presence of specific NH3-transporting and NH4(+)-transporting proteins in specific renal epithelial cells. Ammonia production and transport are regulated by a variety of factors, including extracellular pH and K(+), and by several hormones, such as mineralocorticoids, glucocorticoids and angiotensin II. This coordinated process of regulated ammonia production and transport is critical for the effective maintenance of acid-base homeostasis.
Topics: Acid-Base Equilibrium; Ammonia; Animals; Biological Transport; Glutamine; Humans; Kidney
PubMed: 23720285
DOI: 10.1002/cphy.c120010 -
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 -
The ISME Journal Sep 2023Ammonia oxidising archaea are among the most abundant living organisms on Earth and key microbial players in the global nitrogen cycle. They carry out oxidation of... (Review)
Review
Ammonia oxidising archaea are among the most abundant living organisms on Earth and key microbial players in the global nitrogen cycle. They carry out oxidation of ammonia to nitrite, and their activity is relevant for both food security and climate change. Since their discovery nearly 20 years ago, major insights have been gained into their nitrogen and carbon metabolism, growth preferences and their mechanisms of adaptation to the environment, as well as their diversity, abundance and activity in the environment. Despite significant strides forward through the cultivation of novel organisms and omics-based approaches, there are still many knowledge gaps on their metabolism and the mechanisms which enable them to adapt to the environment. Ammonia oxidising microorganisms are typically considered metabolically streamlined and highly specialised. Here we review the physiology of ammonia oxidising archaea, with focus on aspects of metabolic versatility and regulation, and discuss these traits in the context of nitrifier ecology.
Topics: Archaea; Nitrification; Ammonia; Nitrogen Cycle; Oxidation-Reduction; Soil Microbiology
PubMed: 37452095
DOI: 10.1038/s41396-023-01467-0