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Ammonia
Kinds of Ammonia Terms modified by Ammonia Selected AbstractsREGULATION OF PHENYLALANINE AMMONIA-LYASE ENZYME IN ANNONA FRUIT: KINETIC CHARACTERISTICS AND INHIBITORY EFFECT OF AMMONIAJOURNAL OF FOOD BIOCHEMISTRY, Issue 2 2007R. MALDONADO ABSTRACT In this work, we analyzed the kinetic properties of phenylalanine ammonia-lyase (PAL) extracted from "cherimoya" (Annona cherimola Mill.) fruits ripened at ambient temperature (20C) and stored under several environmental conditions, including high CO2 levels (20%) and low temperature (6C). The effect of different ammonia-related compounds on cherimoya PAL activity was also evaluated. PAL exhibited two different Kmvalues for L-phenylalanine (L-Phe ) and negative substrate cooperativity, with Hill coefficient (napp) values reaching 0.64 and 0.71 for low temperature and high CO2 levels, respectively. The kinetic analysis revealed that ammonia produced mixed inhibition of PAL enzyme, with inhibition constants (Ki and Ki,) values of 0.57 ± 0.2 mM and 2.54 ± 0.2 mM. We propose that the regulation of PAL by ammonia inhibition and the negative cooperativity may be essential in adjusting the active phenylpropanoid metabolism in Annonas to the requirement of L-Phe and in consequence, to the carbon skeleton demand for other anabolic pathways. [source] Miscibility Gap in the System Cesium Amide/Ammonia, CsNH2/NH3 , Thermodynamic Investigations.CHEMINFORM, Issue 26 2003Dieter Peters Abstract For Abstract see ChemInform Abstract in Full Text. [source] Evaluation of methods to remove ammonia interference in marine sediment toxicity tests,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2000James A. Ferretti Abstract Ammonia naturally accumulates to high concentrations in nonsurficial marine sediments. It can also interfere and confound interpretation of toxicity from persistent anthropogenic chemicals in tests with laboratory amphipods. Renewal of overlying water has become a standardized procedure to decrease pore-water ammonia. Our objective was to propose an alternative technique for decreasing pore-water ammonia concentrations. Sediment samples with ammonia concentrations of 70 and 155 mg/L were purged of toxic concentrations in pore-water ammonia using the existing procedure of performing two renewals of overlying water per day. A thin-layer technique, which involved increasing the sediment surface area during the purging period, decreased the ammonia concentration by as much as 4.5-fold faster than the conventional purging protocol. Minimal decreases in concentrations of polycyclic aromatic hydrocarbons, heavy metals, and total organic carbon were found among all the purging techniques. Toxicity tests with the marine amphipod Ampelisca abdita suggest that minimizing the time required to purge a sediment of ammonia is critical in maintaining the integrity of the sample. The thin-layer purging technique appears to be an effective method of decreasing pore-water ammonia concentrations in sediments before laboratory toxicity testing with amphipods. [source] Rare Earth Benzotriazolates: Coordination Polymers Incorporating Decomposition Products from Ammonia to 1,2-Diaminobenzene in,1[Ln(Btz)3(BtzH)] (Ln = Ce, Pr), ,1[Ln(Btz)3{Ph(NH2)2}] (Ln = Nd, Tb, Yb), and ,1[Ho2(Btz)6(BtzH)(NH3)],EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2006Klaus Müller-Buschbaum Abstract The solvent-free melt reactions of benzotriazole (BtzH, C6H4N2NH) with rare earth metals result in three different types of benzotriazolate coordination polymers. Early 4f metals yield ,1[Ln(Btz)3(BtzH)] [Ln = Ce (1), Pr (2)], from neodymium to ytterbium the type ,1[Ln(Btz)3{Ph(NH2)2}] is observed [Ln = Nd (3), Tb (4), Yb (5)], whereas the late 4f metal Ho gives ,1[Ho2(Btz)6(BtzH)(NH3)] (6). Depending on the reaction conditions and the respective rare earth element, ligand fragments originating from decomposition products are incorporated in the coordination polymers. Compounds 1,3 and 6 were obtained as single crystals and their crystal structures determined by single-crystal X-ray analysis, whilst 4 and 5 were obtained as powders. X-ray powder diffraction shows the isotypic character of polymers 3, 4, and 5. The benzotriazolates contain trivalent lanthanide ions with complete nitrogen coordination. Decomposition of the ligand accompanies the formation of the coordination polymers. X-ray analysis was combined with thermal analysis and mass spectrometry to investigate the influence of reaction temperatures on ligand decomposition. Ln-benzotriazolates exhibit aspects of materials science such as luminescence {5D4,7FJ, J = 4,6 for ,1[Tb(Btz)3{Ph(NH2)2}] (4)} without quenching by concentration. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] N -Acetylation as a Means to Activate Polyfluoroarylamines for Selective ortho -Hydrodefluorination by Zinc in Aqueous Ammonia: A Concise Route to Polyfluorobenzo Azaheterocycles,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2007Sergey S. Laev Abstract N -Acetylation of polyfluoroarylamines is proposed as a meansto remove the amino group blocking effect of their hydrodefluorination by zinc in aqueous ammonia. With pentafluoroacetanilide, the Zn ion specific effect has been demonstrated to be responsible for ortho hydrodefluorination. This regiochemistry is accompanied by the removal of a fluorine atom from the para position, which occurs predominantly in the initial phase of the process in the absence of deliberately added zinc salt. The CuCl2 additive has been found to accelerate the reaction and to propel it to double defluorination. Quantum chemical calculations suggest a diminished electron affinity of pentafluoroaniline, which is responsible for its inertness in relation to the hydrodefluorination reaction. The pentafluoroaniline radical anion, which essentially has a nonplanar structure, is prone to easy fragmentation to give an aminotetrafluorophenyl radical. For pentafluoroacetanilide, CVA experiments and quantum chemical calculations predict that the pentafluorophenyl moiety serves as the electron receptor and that the acetamido group is twisted out of coplanarity with the benzene ring; thus, together with the electron-withdrawing effect of the acetyl group, the amino group blocking effect is suppressed. On this ground, the selective ortho hydrodefluorination of polyfluoroacetanilides is developed as an important protocol for the expeditious and general synthesis of polyfluorobenzo azaheterocycles via readily accessible polyfluoroarylamines from base polyfluoroarenes. Its applicability has been illustrated by preparing quinolines that possess a polyfluorinated benzene moiety by the Skraup synthesis utilizing crude polyfluoroacetanilide hydrodefluorination products as starting materials. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Study of the Reaction of 3-Formylrifamycin SV with Gaseous Ammonia and Acetone,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2006Krzysztof Bujnowski Abstract In the second stage of our study concerning the search for new antibacterial rifamycin antibiotics, reaction of the aldehydes 3-formylrifamycin SV (1) and 25- O -deacetyl-3-formylrifamycin SV with ammonia and acetone has been investigated. A new synthetic method for the preparation of a new group of rifamycin derivatives with a cyclic substituent at C-3 having a 4-piperidone structure, represented by compounds 6a, 6b, and 7a, has been developed. The structures of the compounds and a reaction mechanism have been proposed on the basis of mass spectrometry results as well as 1D and 2D 1H and 13C NMR analysis. The results of the in vitro tests confirm the antituberculous activity of the synthesized compounds. Furthermore, 6a, which is isolated in good yield, is a promising substrate for a new class of rifamycin derivatives. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Graphite Oxides Obtained from Porous Graphite: The Role of Surface Chemistry and Texture in Ammonia Retention at Ambient ConditionsADVANCED FUNCTIONAL MATERIALS, Issue 10 2010Mykola Seredych Abstract Graphite oxides (GO) synthesized using Brodie and Hummers methods are tested for ammonia adsorption at ambient conditions with different contents of water in the system. Surface characterization before and after exposure to ammonia is performed using XRD, FTIR spectroscopy, potentiometric titration, thermal analysis, adsorption of nitrogen, and XPS. Oxidation of the same porous graphite using two methods results in materials with different textural and chemical features. On GO obtained using the Brodie method mainly epoxy and carboxylic groups are present whereas on the GO obtained using the Hummers method chemisorbed oxygen is also found. The contribution of the carboxylic groups in the latter material is greater. It also contains sulfur either in sulfones or as residual sulfuric acid. Ammonia is adsorbed either via reaction with surface groups or dissolution in water. The former is responsible for strong adsorption. The evidence of the catalytic effect of the carbon surface on activation of oxygen leading to surface oxidation is also observed. [source] Enhanced Adsorption of Ammonia on Metal-Organic Framework/Graphite Oxide Composites: Analysis of Surface InteractionsADVANCED FUNCTIONAL MATERIALS, Issue 1 2010Camille Petit Abstract Composites of the metal-organic framework (MOF), MOF-5, and graphite oxide (GO) with different ratios of the two components are prepared and tested in ammonia removal under dry conditions. The parent and composite materials are characterized before and after exposure to ammonia by sorption of N2, X-ray diffraction, thermal analyses, and FT-IR spectroscopy. The results show a synergetic effect resulting in an increase in the ammonia uptake compared to the parent materials. It is linked to enhanced dispersive forces in the pore space of the composites. Additionally, ammonia interacts with zinc oxide tetrahedra via hydrogen bonding and is intercalated between the layers of GO. Retention of a large quantity of ammonia eventually leads to a collapse of the MOF-5 structure in the composites. The effect resembles that observed when MOF-5 is exposed to water. Taking into account the similarity of ammonia and water molecules, it is hypothesized that ammonia causes a destruction of the MOF-5 and composite structure as a result of its hydrogen bonding with the zinc oxide clusters. [source] Inhibition of glutamine transport into mitochondria protects astrocytes from ammonia toxicityGLIA, Issue 8 2007V. B. R. Pichili Abstract Hepatic encephalopathy (HE) is a major neurological complication that occurs in the setting of severe liver failure. Ammonia is a key neurotoxin implicated in this condition, and astrocytes are the principal neural cells histopathologically and functionally affected. Although the mechanism by which ammonia causes astrocyte dysfunction is incompletely understood, glutamine, a by-product of ammonia metabolism, has been strongly implicated in many of the deleterious effects of ammonia on astrocytes. Inhibiting mitochondrial glutamine hydrolysis in astrocytes mitigates many of the toxic effects of ammonia, suggesting the involvement of mitochondrial glutamine metabolism in the mechanism of ammonia neurotoxicity. To determine whether mitochondriaare indeed the organelle where glutamine exerts its toxic effects, we examined the effect of L -histidine, an inhibitor of mitochondrial glutamine transport, on ammonia-mediated astrocyte defects. Treatment of cultured astrocytes with L -histidine completely blocked or significantly attenuated ammonia-induced reactive oxygen species production, cell swelling, mitochondrial permeability transition, and loss of ATP. These findings implicate mitochondrial glutamine transport in the mechanism of ammonia neurotoxicity. © 2007 Wiley-Liss, Inc. [source] Ammonia impairs neutrophil phagocytic function in liver disease,HEPATOLOGY, Issue 4 2008Debbie L. Shawcross Hyperammonemia is a feature of liver failure, which is associated with increased risk of infection. The aims of the present study were to determine in vitro, in rats fed an ammoniagenic diet and in patients with cirrhosis, whether induction of hyperammonemia results in neutrophil dysfunction. As hyperammonemia produces cell swelling, we explored the role of the osmoregulating, p38 mitogen-activated protein kinase (p38MAPK) pathway in mediating this neutrophil dysfunction. Neutrophils were isolated from blood of healthy volunteers and incubated with either 75 ,M ammonia or phosphate-buffered saline. Both groups were studied under hyponatremic conditions and/or with the addition of p38MAPK modulators. Neutrophil phagocytosis was measured in naive rats and rats fed an ammoniagenic diet and in patients with stable cirrhosis given placebo (n = 8) or an amino acid solution inducing hyperammonemia (n = 8). Cell volume and phagocytosis was analyzed by fluorescent-activated cell sorting using fluorescein isothiocyanate,labeled E. coli. p38MAPK phosphorylation was measured by western blotting. In healthy neutrophils incubated with ammonia and in rats fed an ammoniagenic diet, neutrophils showed evidence of swelling, impaired phagocytosis, and increased spontaneous oxidative burst compared to controls. Phagocytosis was significantly impaired in patients with induced hyperammonemia compared to placebo. The effects of hyperammonemia and hyponatremia were synergistic. The p38MAPK intracellular signaling pathways were activated in healthy neutrophils exposed to ammonia in association with increased burst activity. Neutrophil phagocytic dysfunction was abrogated by the addition of a p38MAPK agonist. Conclusion: Ammonia produces neutrophil swelling and impairs neutrophil phagocytosis. The p38MAPK intracellular signaling pathway has been shown to be important in mediating the ammonia-induced neutrophil dysfunction. (HEPATOLOGY 2008.) [source] Interorgan ammonia and amino acid metabolism in metabolically stable patients with cirrhosis and a TIPSSHEPATOLOGY, Issue 5 2002Steven W. M. Olde Damink Ammonia is central to the pathogenesis of hepatic encephalopathy. This study was designed to determine the quantitative dynamics of ammonia metabolism in patients with cirrhosis and previous treatment with a transjugular intrahepatic portosystemic stent shunt (TIPSS). We studied 24 patients with cirrhosis who underwent TIPSS portography. Blood was sampled and blood flows were measured across portal drained viscera, leg, kidney, and liver, and arteriovenous differences across the spleen and the inferior and superior mesenteric veins. The highest amount of ammonia was produced by the portal drained viscera. The kidneys also produced ammonia in amounts that equaled total hepatosplanchnic area production. Skeletal muscle removed more ammonia than the cirrhotic liver. The amount of nitrogen that was taken up by muscle in the form of ammonia was less than the glutamine that was released. The portal drained viscera consumed glutamine and produced ammonia, alanine, and citrulline. Urea was released in the splenic and superior mesenteric vein, contributing to whole-body ureagenesis in these cirrhotic patients. In conclusion, hyperammonemia in metabolically stable, overnight-fasted patients with cirrhosis of the liver and a TIPSS results from portosystemic shunting and renal ammonia production. Skeletal muscle removes more ammonia from the circulation than the cirrhotic liver. Muscle releases excessive amounts of the nontoxic nitrogen carrier glutamine, which can lead to ammonia production in the portal drained viscera (PDV) and kidneys. Urinary ammonia excretion and urea synthesis appear to be the only way to remove ammonia from the body. [source] An Efficient Copper-Catalyzed Amination of Aryl Halides by Aqueous AmmoniaADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Deping Wang Abstract The copper(I) bromide/1-(5,6,7,8-tetrahydroquinolin-8-yl)-2-methylpropan-1-one (CuBr- L3) combination catalyzed the cross-coupling reactions between aryl or heteroaryl halides and aqueous ammonia with high yields to produce primary aromatic or heteroaromatic amines at room temperature or under mild conditions. [source] The effect of total plasma exchange on fulminant hepatic failureJOURNAL OF CLINICAL APHERESIS, Issue 2 2006M. Akdogan Total plasma exchange (TPE) corrects coagulopathy in patients with liver disease and removes hepatotoxins/cytokines. This improvement is transient but can be used as a bridge until an organ is identified for liver transplantation (LTx) or the liver itself regenerates. Our aim was to retrospectively assess the efficacy of TPE in fulminant hepatic failure (FHF) and its impact on liver function tests. Between 1995,2001, 39 patients with FHF who had undergone TPE were reviewed. FHF was defined according to the O'Grady criteria based on the duration of encephalopathy as well as jaundice. TPE was performed using the Cobe Spectra TPE (Gambro®) in Liver Intensive Care Unit, continued on a daily basis, until either adequate clinical response was achieved, the patient expired, or transplantation occurred. INR, PTT, Fibrinogen, ALT, AST, GGT, BUN, Ammonia, and Total Bilirubin were analyzed before and after TPE. Student's t -test and chi-square test and ANOVA were used for statistical analysis. Thirty-nine patients with FHF (31 females, 8 males with mean age of 32.3, range: 7,64) underwent TPE. Coagulopathy, hyperbilirubinemia, hyperammonemia were significantly improved (P < 0.05). Twenty-one patients survived (54%), 12 required LTx, and 18 patients (including one after LTx) expired. TPE was found to be significantly effective for correction of coagulopathy and improvement of liver tests. This intervention can be considered for temporary liver support until recovery or liver transplantation. J Clin Apheresis 2005. © 2005 Wiley-Liss, Inc. [source] Ammonia in estuaries and effects on fishJOURNAL OF FISH BIOLOGY, Issue 6 2005F. B. Eddy This review aims to explore the biological responses of fish in estuaries to increased levels of environmental ammonia. Results from laboratory and field studies on responses of fish to varying salinity and their responses increased ammonia will be evaluated, although studies which examine responses to ammonia, in relation to varying salinity, pH and temperature together are rare. In a survey of British estuaries the continuous measurement of total ammonia showed values that ranged from background levels increasing up to c. 10 mg N l,1 although higher values have been noted sporadically. In outer estuaries pH values tended to stabilize towards sea water values (e.g. c. pH 8). Upper reaches of estuaries are influenced by the quality of their fresh waters sources which can show a wide range of pH and water quality values depending on geological, climatic and pollution conditions. In general the ammonia toxicity (96 h LC50) to marine species (e.g. 0·09,3·35 mg l,1 NH3) appears to be roughly similar to freshwater species (e.g. 0·068,2·0 mg l,1 NH3). Ammonia toxicity is related to differences between species and pH rather than to the comparatively minor influences of salinity and temperature. In the marine environment the toxicity of ionized ammonia should be considered. The water quality standard for freshwater salmonids of 21 ,g l,1 NH3,N was considered to be protective for most marine fish and estuarine fish although the influence of cyclical changes in pH, salinity and temperature were not considered. During ammonia exposures, whether chronic or episodic, estuarine fish may be most at risk as larvae or juveniles, at elevated temperatures, if salinity is near the seawater value and if the pH value of the water is decreased. They are also likely to be at risk from ammonia intoxication in waters of low salinity, high pH and high ammonia levels. These conditions are likely to promote ammonia transfer from the environment into the fish, both as ionized and unionized ammonia, as well as promoting ammonia retention by the fish. Fish are more likely to be prone to ammonia toxicity if they are not feeding, are stressed and if they are active and swimming. Episodic or cycling exposures should also be considered in relation to the rate at which the animal is able to accumulate and excrete ammonia and the physiological processes involved in the transfer of ammonia. In the complex environment of an estuary, evaluation of ammonia as a pollutant will involve field and laboratory experiments to determine the responses of fish to ammonia as salinity and temperature vary over a period of time. It will also be necessary to evaluate the responses of a variety of species including estuarine residents and migrants. [source] Characteristics of ammonia permeation through porous silica membranesAICHE JOURNAL, Issue 5 2010Masakoto Kanezashi Abstract A sol,gel method was applied for the preparation of silica membranes with different average pore sizes. Ammonia (NH3) permeation/separation characteristics of the silica membranes were examined in a wide temperature range (50,400°C) by measurement of both single and binary component separation. The order of gas permeance through the silica membranes, which was independent of membrane average pore size, was as follows: He > H2 > NH3 > N2. These results suggest that, for permeation through silica membranes, the molecular size of NH3 is larger than that of H2, despite previous reports that the kinetic diameter of NH3 is smaller than that of H2. At high temperatures, there was no effect of NH3 adsorption on H2 permeation characteristics, and silica membranes were highly stable in NH3 at 400°C (i.e., gas permeance remained unchanged). On the other hand, at 50°C NH3 molecules adsorbed on the silica improved NH3 -permselectivity by blocking permeation of H2 molecules without decreasing NH3 permeance. The maximal NH3/H2 permeance ratio obtained during binary component separation was ,30 with an NH3 permeance of ,10,7 mol m,2 s,1 Pa,1 at an H2 permeation activation energy of ,6 kJ mol,1. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Mechanism of the protective effect of hypothermia on ammonia toxicity in astrocytesJOURNAL OF NEUROCHEMISTRY, Issue 2002C. Zwingmann Ammonia is a key factor in the pathogenesis of hepatic encephalopathy (HE). Acute ammonia treatment causes energy failure of astrocytes, which are able to compensate partly by increased anaerobic metabolism as a means of making up for the energetic shortfall. As hypothermia offers protection from severe encephalopathy and lactate accumulation in liver failure, we investigated the mechanism by which hypothermia protects against ammonia toxicity by multinuclear NMR spectroscopy. 12 h exposure to 5 mm NH4CL decreased the phosphocreatine (PCr)/creatine (Cr) and ATP/ADP ratios to 65 and 76% of control, increased synthesis and release of glutamine to 200,250% and led to a significant stimulation of glycolytic activity reflected by increased uptake and consumption of glucose and accumulation of de novo synthesized intra- and extracellular lactate to 161 and 230% of control. The protective effect of mild hypothermia was evident from inhibiton of lactate accumulation and restoration of ammonia-induced depletion of PCr/Cr. Moderate hypothermia led to an increase of PCr/Cr ratio and inhibited lactate synthesis to 14% of normothermic control, but did not prevent the ATP decrease. While hypothermia inhibited glycolytic flux, intracellular glutamine remained elevated. The results suggest that hypothermia-induced protection against ammonia toxicity results from reduction of cellular energy demand leading to inhibition of anaerobic glucose metabolism and a compensatory stimulation of mitochondrial energy production. Acknowledgements:, Funded by CIHR Canada. [source] Fast and Almost Complete Nitridation of Mesoporous Silica MCM-41 with Ammonia in a Plug-Flow ReactorJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2010Fumitaka Hayashi The title reaction proceeded well to yield silicon (oxy)nitride at 973,1323 K using a plug-flow reactor. The degree of nitridation was studied as a function of temperature and time of nitridation, the sample weight, and the flow rate of ammonia. It was dependent on the reaction temperature and the amount of ammonia supplied per sample weight. The nitridation at 1273 K for 10,25 h yielded the oxynitride with 36,39 wt% nitrogen, which was very close to 40 wt% of Si3N4. Characterization with X-ray diffraction, field-emission scanning electron microscopy and transmission electron microscopy measurements, and nitrogen adsorption revealed the conversion of MCM-41 to the corresponding oxynitride without essential loss of the mesoporous structure, the decrements of the lattice constant and the pore diameter by 20,35%, and the increments of the wall thickness by ca. 45%. Solid-state 29Si nuclear magnetic resonance spectra during the nitridation clearly showed fast decrease in SiO4 species and slow in SiO3(OH). Various intermediate species, SiOxNy(NH2 or NH)z, were observed to be formed and finally, ca. 70% SiN4 species, ca. 20% SiN3(NH2 or NH), and ca. 10% SiON2(NH2 or NH) were produced, being consistent with the results of the above mentioned elemental analysis. [source] Ammonia-, Sodium Chloride-, and Calcium Sulfate-induced Changes in the Stress Responses of Jundiá, Rhamdia quelen, JuvenilesJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 6 2009Paulo César Falanghe Carneiro Salt (NaCl) and gypsum (CaSO4) are used as water additives to mitigate fish stress and improve specimen survival. High stocking densities and the transportation of fish can increase aqueous ammonia, which can, in turn, alter fish cortisol secretion. The objectives of this study were to assess the effects of salt, gypsum, and aqueous ammonia on some stress-induced physiological responses of jundiá, Rhamdia quelen, juveniles induced by captivity and handling, and to determine the lethal ammonia concentration for this species. Jundiá juveniles were subjected to the following five treatments: water only, water + ammonia (0.4 mg/L), water + NH3 + NaCl (6 g/L), water + NH3 + gypsum (150 mg/L), and water + NH3 + NaCl + gypsum. Blood samples were taken after intervals of 1, 5, 24, and 96 h, and the concentrations of cortisol, glucose, chloride, ammonia, and hematocrit were determined. The NH3 LC50 value after 96 h of exposure (LC50,96h) was measured to be 1.9 mg/L NH3. Either salt or gypsum reduced both cortisol and glucose levels during most of the experimental period, but the combination of both reduced these levels even further. The combined use of NaCl and CaSO4 demonstrates a synergic effect on mitigating stress responses induced by handling and aqueous ammonia in jundiá juveniles. [source] The Effect of Storage on Ammonia Concentration in Canine Packed Red Blood Cells.JOURNAL OF VETERINARY EMERGENCY AND CRITICAL CARE, Issue 1 2001DACVECC, Lori S. Waddell DVM Abstract Objective: To determine the effect of storage on ammonia concentration in canine packed red blood cell (pRBC) units. Design: In vitro and in vivo study. Setting: University Veterinary Teaching Hospital. Interventions: Ammonia concentration was measured in 7 units of canine pRBC prepared in citrate-phosphate-dextrose (CPD) and Adsola on Days 1 and 35 of storage. Ammonia was measured in 4 additional units of canine pRBC on Days 0, 7, 14, 21, 28, and 35. Plasma ammonia was also determined in 5 anemic dogs receiving pRBC. Measurements and Main Results: Ammonia concentration increased from 73 ± 15 mmol/L (mean ± SD) on Day 1 to 800 ± 275 mmpl/L on Day (p<0.001). When measured every 7 days in 4 units of canine pRBC, ammonia concentration increased from 23 ± 8 mmol/L on Day 0 to 179 ± 13 mmol/L (Day 7), 276 ± 56 mmol/L (Day 14). 383 ± 47 mmol/L (Day21), 466 ± 30 mmol/L (Day 28), and 562 ± 27 mmol/L (Day 35) (p<0.05 for all comparisons). In a preliminary study, plasma ammonia concentration measured in blood samples from 5 anemic dogs without primary liver disease immediately before and after transfusion with 5,10 ml/kg of stored pRBC remained in the normal reference range. Conclusions: The ammonia concentration in stored canine pRBC increased markedly with time. In this preliminary study, ammonia concentrations in dogs without primary liver disease did not increase above the reference range after transfusion with pRBC. [source] Effects of L-Asparaginase on Plasma Amino Acid Profiles and Tumor Burden in Cats with LymphomaJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 4 2007A.K. LeBlanc Background: L-Asparaginase (Elspara), is an Escherichia coli -derived enzyme that depletes lymphoma cells of asparagine, inhibiting protein synthesis and resulting in cell death. The single agent response rate in cats with lymphoma and impact of L-asparaginase on plasma amino acid concentrations is unknown. Hypotheses: L-Asparaginase significantly reduces plasma asparagine concentrations and has demonstrable efficacy against untreated lymphoma in cats. Animals: Thirteen cats with confirmed lymphoma (LSA) of any anatomic site were given 1 dose 400 IU/kg IM) of L-asparaginase for initial LSA treatment. Methods: Plasma collected at 0, 2, and 7 days after L-asparaginase therapy was assayed for ammonia, asparagine, aspartic acid, glutamine, and glutamic acid concentrations. Cats were restaged 7 days later to assess tumor response. Results: Eight cats had T-cell LSA, 4 cats had B-cell LSA, and 1 cat's immunophenotype was unknown. Two complete and 2 partial responses to L-asparaginase were seen. Four cats had stable disease, and 5 cats had progressive disease. Ammonia and aspartic acid concentrations were increased from baseline at 2 and 7 days posttreatment. Asparagine concentrations were decreased from baseline at 2 days but not 7 days posttreatment. Glutamic acid concentrations were increased at day 2 compared to day 7 posttreatment but not compared to baseline. Glutamine concentrations were unchanged. Conclusions and Clinical Importance: L-Asparaginase significantly reduced asparagine concentrations within 2 days of treatment, but this effect was lost within 7 days. The apparent overall response rate of feline LSA to L-asparaginase in this study was 30%. [source] Effects of sodium benzoate on the complications of 1.ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 20045% glycine solution using two different intravesical pressures during bladder irrigation Background:, In this experimental study we researched the effects of sodium benzoate on the complications of 1.5% glycine solution using with two different intravesical pressures during bladder irrigation. Methods:, Thirty-six male adult New Zealand rabbits with body weight ranging from 1500 to 2800 g were used in the experiments. The rabbits were randomly allocated to four groups. In groups 1 and 2, 500 ml of 1.5% gylcine was used as irrigating fluid during 30 min, but only group 2 received 500 mg kg,1 of sodium benzoate treatment by oral route immediately after irrigation. In groups 3 and 4, 500 ml of 1.5% glycine was used as irrigating fluid during 60 min, but only group 4 received the same treatment as group 2. Ammonia, urea, sodium, potassium, hemoglobin, hemotocrit and platelet levels were studied at preirrigation and postirrigation on the 4 h and 24 h. Also electrocardiographic (ECG) changes were monitored at the same time with blood parameters. Results:, At 4 h postirrigation, Na+ levels were decreased significantly in group 1 and non-significantly in group 3 when compared with preirrigation levels. But these levels were not changed in groups 2 and 4. Both at 4 h and 24 h, ammonia and urea levels were significantly increased in groups 1 and 3. Ammonia level was decreased but the urea level was not changed in groups 2 and 4 at the same time points. K+ level was significantly changed only in group 1 at 4 h and 24 h. Hemoglobin and hemotocrit concentrations were decreased both at 4 h and 24 h compared with preirrigation levels in all groups. Also there were ECG changes between the treated and untreated groups. Conclusion:, Sodium benzoate was very effective against the complications of 1.5% glycine during bladder irrigation experimentally. But this needs further investigation, especially for the applicability of this new treatment model in human TURP syndrome. [source] Acrodermatitis Enteropathica-like Dermatosis Associated with Ornithine Transcarbamylase DeficiencyPEDIATRIC DERMATOLOGY, Issue 4 2007José C. Pascual M.D. Ornithine transcarbamylase deficiency is the most frequent urea cycle disorder. It is a hereditary-X-linked disease with over 150 mutations described (1).Ornithine transcarbamylase deficiency causes vomiting, lethargy, hyperventilation, and even death, mainly in the neonatal period (2). Ammonia, an extremely toxic molecule for the organism, is generated during protein catabolism and is accumulated in patients with this deficiency. Part of the treatment consists of a low-protein diet, to avoid hyperammonemia episodes, which can even have a fatal outcome. Patients can become deficient in several amino acids, either through the low-protein diet or directly through the primary enzyme deficiency; this in turn can cause an acrodermatitis enteropathica-like dermatosis. [source] Reduction of Gallium Vacancy Concentration in Gallium Nitride Grown with Preheated AmmoniaPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2003S.-Y. Kwon Abstract The use of ammonia preheater reduces the Ga vacancy (VGa) concentration in GaN. The epilayers grown with or without preheated ammonia had little differences in structural properties from X-ray diffraction and transmission electron microscopy. It was found, however, that the GaN epilayers grown with unheated ammonia had more charge compensation centers. The intensities of yellow luminescence (YL) in GaN epilayers grown with preheated ammonia decreased with Si doping, whereas those grown with unheated ammonia increased with Si doping. It is suggested that the use of preheated ammonia reduced the VGa concentration in GaN without altering structural properties. [source] History of Process SafetyPROCESS SAFETY PROGRESS, Issue 2 2009A history of process safety, loss prevention in the American Institute of Chemical Engineers Abstract Process safety has always been an important consideration in chemical engineering, and the activities of the American Institute of Chemical Engineers (AIChE) have expanded over the years to more formally focus on this critical aspect of chemical engineering practice. Early initiatives included the annual symposia on Safety in Ammonia and Related Plants, dating back to the early 1950s, and the Loss Prevention Symposium, first held in 1967. These activities led to the formation of the AIChE's Safety and Health Division in 1979, and the division assumed responsibility for these existing programming activities. Following the Bhopal tragedy in India, AIChE formed the Center for Chemical Process Safety (CCPS) in 1985 as an industry alliance to share and enhance process safety expertise in the industry. One of the early CCPS activities was the creation of the Safety and Chemical Engineering Education (SACHE) program to enhance teaching of process safety in the university chemical engineering curriculum. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2009 [source] An exploratory comparative study of volatile compounds in exhaled breath and emitted by skin using selected ion flow tube mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 4 2008Claire Turner Selected ion flow tube mass spectrometry (SIFT-MS) has been used to carry out a pilot parallel study on five volunteers to determine changes occurring in several trace compounds present in exhaled breath and emitted from skin into a collection bag surrounding part of the arm, before and after ingesting 75,g of glucose in the fasting state. SIFT-MS enabled real-time quantification of ammonia, methanol, ethanol, propanol, formaldehyde, acetaldehyde, isoprene and acetone. Following glucose ingestion, blood glucose and trace compound levels were measured every 30,min for 2,h. All the above compounds, except formaldehyde, were detected at the expected levels in exhaled breath of all volunteers; all the above compounds, except isoprene, were detected in the collection bag. Ammonia, methanol and ethanol were present at lower levels in the bag than in the breath. The aldehydes were present at higher levels in the bag than in breath. The blood glucose increased to a peak about 1,h post-ingestion, but this change was not obviously correlated with temporal changes in any of the compounds in breath or emitted by skin, except for acetone. The decrease in breath acetone was closely mirrored by skin-emitted acetone in three volunteers. Breath and skin acetone also clearly change with blood glucose and further work may ultimately enable inferences to be drawn of the blood glucose concentration from skin or breath measurements in type 1 diabetes. Copyright © 2008 John Wiley & Sons, Ltd. [source] A coupled dispersion and exchange model for short-range dry deposition of atmospheric ammoniaTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 618 2006Benjamin Loubet Abstract The MODDAS-2D model (MOdel of Dispersion and Deposition of Ammonia over the Short-range in two dimensions) is presented. This stationary model couples a two-dimensional Lagrangian stochastic model for short-range dispersion, with a leaf-scale bi-directional exchange model for ammonia (NH3), which includes cuticular uptake and a stomatal compensation point. The coupling is obtained by splitting the upward and downward components of the flux, which can be generalized for any trace gas, and hence provides a way of simply incorporating bi-directional exchanges in existing deposition velocity models. The leaf boundary-layer resistance is parametrized to account for mixed convection in the canopy, and the model incorporates a stability correction for the Lagrangian time-scale for vertical velocity, which tends to increase the Lagrangian time-scale in very stable conditions compared with usual parametrizations. The model is validated against three datasets, where concentrations of atmospheric NH3 were measured at several distances from a line source. Two datasets are over grassland and one is over maize, giving a range of canopy structure. The model correctly simulates the concentration in one situation, but consistently overestimates it at further distances or underestimates it at small distances in the two other situations. It is argued that these discrepancies are mainly due to the lack of length of one of the line sources and non-aligned winds. Analysis shows that the surface exchange parameters and the turbulent mixing at the source level are the predominant factors controlling short-range deposition of NH3. Copyright © 2006 Royal Meteorological Society [source] Titelbild: Catalytic Oxidative Synthesis of Nitriles Directly from Primary Alcohols and Ammonia (Angew. Chem.ANGEWANDTE CHEMIE, Issue 34 200934/2009) Trägerfixiertes Rutheniumhydroxid erwies sich als effizienter Heterogenkatalysator für die aerobe oxidative Synthese von Nitrilen, wichtigen Ausgangsverbindungen für die Produktion von Pharmaka, Agro- und Feinchemikalien. N. Mizuno et,al. zeigen in ihrer Zuschrift auf S.,6404,ff., dass mit diesem Verfahren Nitrile direkt aus Alkoholen oder Aldehyden und Ammoniak hergestellt werden können, was es zu einer neuen Möglichkeit für eine "grüne" Nitrilsynthese macht. [source] Catalytic Oxidative Synthesis of Nitriles Directly from Primary Alcohols and Ammonia,ANGEWANDTE CHEMIE, Issue 34 2009Takamichi Oishi Gute Grundlage: Der Rutheniumhydroxid-Trägerkatalysator Ru(OH)x/Al2O3 vermittelt effizient die aerobe oxidative Synthese von Nitrilen direkt aus primären Alkoholen (oder Aldehyden) und Ammoniak. Der zurückgewonnene Katalysator konnte ohne merklichen Leistungsverlust wiederverwendet werden. [source] Benefits of using the probiotic Efinol®L during transportation of cardinal tetra, Paracheirodon axelrodi (Schultz), in the AmazonAQUACULTURE RESEARCH, Issue 2 2009Levy Carvalho Gomes Abstract The objective of this experiment was to test the probiotic Efinol®L during transportation of cardinal tetra, Paracheirodon axelrodi (Schultz). For the transportation, fish were distributed in 18 plastic tanks, of which nine contained the Efinol®L (10 mg L,1; probiotic treatment) and the remaining had no probiotic (control treatment). Transport lasted 24 h and three different boxes of each treatment were sampled at 3, 12 and 24 h. Up to the 12-h sampling period, no significant difference in the survival was observed; on the other hand, survival was higher at the end of the transport (24 h) in the probiotic treatment. No significant difference was found in dissolved oxygen and temperature between treatments. Conductivity, pH and alkalinity increased along the transport, but without a difference between treatments. Ammonia increased in all treatments, although it was significantly lower in the probiotic group at 24 h. Cortisol levels were significantly higher in all transported fish when compared with the basal values. At 24 h, cortisol levels in control fish were significantly higher than those in the probiotic treatment. With the observed results, we are able to conclude that the probiotic Efinol®L is efficient during cardinal transport, lowering the mortality and helping maintain water quality possibly by lowering metabolic wastes. [source] Response surface modeling and optimization for production of ammonia from urea in a batch reactorASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2009J. N. Sahu Abstract Ammonia is applied to removal of NOx contaminates contained in a flue gas stream from energy producing boilers and increase of efficiency of an electrostatic precipitator for removal of fly ash from flue gas stream from a boiler using fossil fuel. In this study, urea hydrolysis for production of ammonia, in different application areas that requires safe use of ammonia, was investigated in a batch reactor. The single and combined effects of operating parameters such as initial feed concentrations, temperature, time and stirring speed on the production of ammonia from urea were analyzed using response surface methodology (RSM). A 24 full factorial central composite experimental design was employed. Analysis of variance (ANOVA) showed a high coefficient of determination value (R2 = 0.976) and satisfactory prediction second-order regression model was derived. The optimum production conditions were determined as temperature, 180 °C; initial feed concentrations, 22.24 wt% of urea; time, 74.9 min and stirring speed, 1150 rpm. At optimum conversion conditions, the conversion of urea for production of ammonia was found to be 75.65%. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||