Study of nitrogen-containing compounds in cigarette smoke by gas chromatography-mass spectrometry.
Explore the source record for details and available documents.
Gas Chromatography-Mass Spectrometry↗
SEARCH · PubMed Health
Results for “Nitrogen Compounds”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Geochemical signatures (C, N, delta13C, delta15N, metals) of suspended matter in the river Weisse Elster (central Germany): their seasonal and flow-related distribution 1997-2001.
Geochemical studies of carbon, nitrogen, delta13C, delta15N as well as Fe, Mn, Cd, Zn, Cr and Hg in suspended matter taken from the river Weisse Elster (central Germany) between 1997 and 2001 reveal significant changes to the composition of the organic sediment load, which correlate with the hydrological period and flow rate. Using C/N ratios and the isotope values of carbon and nitrogen as source indicators, it was found that the organic suspended matter fractions in hydrological winter periods comprise both resuspended mortal plankton material from the riverbed and terrigenous C3 plant material from the clastic input. During the 6 month summer periods, increased bioproductivity results in more dissolved carbon and mineral nitrogen compounds being taken up by the freshly formed aquatic organic substance (freshwater plankton). These compounds stem from bacterial breakdown processes affecting organic components of the river sediment and/or the peripheral soil zone. Increasing fractions of freshwater plankton during the summer period are accompanied by an increase in the nitrogen content and by isotope signatures shifting (delta13C to lower but delta15N to higher values) in the suspended matter. Seasonally opposite correlations between metal contents (e.g. Cd, Zn, Cr, Hg and Fe) and the carbon and nitrogen levels of suspended matter (significantly positive in winter and significantly negative in summer) show that in suspended matter these elements mostly bind to resuspended mortal (rather than the freshly formed living aquatic) organic substance. According to long-term measuring series, between 1993 and 2002 the levels of heavy metals (especially cadmium) in the suspended matter of the river Weisse Elster decreased. Similarly, between 1997 and 2001 the oxygen level in the river Weisse Elster improved. This caused the faster breakdown of organic substance on the riverbed, resulting in the increased uptake of 15N-rich nitrogen compounds into the fresh aquatic organic substance formed every year, and an increase in the conversion of dissolved manganese in the water into insoluble manganese compounds in the river sediment.
Carbon↗
The pollution load by nitrogen and phosphorus in the Jadro River.
The objective of the investigations of the Jadro River, located in Croatia, was to estimate the nitrogen and phosphorus loads in the Jadro River spring and its streamflow by calculating the load in kg/day or tons/year and to compare this with the load for the maximum allowed concentrations (MAC) for drinking water (Official Bulletin, No 46/94) expressed in kg/day or tons/year. Daily pollution loads at the Jadro River spring for total N ranged from 0 to 304 kg, for NH3-N from 0 to 38 kg, for NO3-N from 0-1321 kg and for PO4-P from 0-92 kg in the period from September 1993 to September 2003. When compared with MAC loads the results prove that the Jadro River spring is not polluted by nitrogen compounds and phosphorus. The average annual load for total N ranged from 10 to 33 t, for NH3-N from 0.25 to 5.15 t, for NO3-N from 40 to 190 t, and for PO4-P from 0.3 to 11.5 t. The nitrogen compounds and phosphorus loads vary from one year to another without any constant decreasing or increasing trends. The annual average loads compared with the average annual MAC loads (especially for NH3-N and PO4-P) show that there were no threats of constant pollution of the spring. The loads for total N and PO4-P along the Jadro River flow from the spring to the fishpond entrance were monitored over a five year period from September 1999 to September 2004. The results show no regularities. The highest annual total nitrogen load of 45 t was recorded at the entrance to the fishpond during the 2002/2003 period. The highest annual PO4-P load of 10 t was measured at the Vidović Bridge during the 2003/2004 period; however, the concentrations of N and P did not exceed the MAC concentrations which are prescribed for drinking water. According to the investigation results of the daily and average annual loads compared with MAC loads for drinking water, it can be concluded that the Jadro River spring and its streamflow are not polluted by nitrogen and phosphorus.
Croatia↗
Effects of prostacyclin and taprostene in splanchnic artery occlusion shock.
Prostacyclin (PGI2) and taprostene (CG-4203) were studied in a highly lethal model of splanchnic artery occlusion (SAO) shock in pentobarbital anesthetized rats. Total occlusion of the superior mesenteric and celiac arteries for 40 min resulted in a severe shock state often resulting in a fatal outcome within 2 h following release of the occlusion. PGI2 or taprostene was infused at a rate of 100 ng/kg/min commencing at occlusion of the celiac and superior mesenteric arteries. Taprostene significantly improved survival time and taprostene treated animals maintained post-reperfusion mean arterial blood pressure (MABP) at significantly higher values compared to rats receiving taprostene vehicle (final MABP 96 +/- 3 vs 45 +/- 3.5 mmHg, p less than 0.001, respectively). In addition, taprostene significantly (p less than 0.05) attenuated the rise in hematocrit in SAO shock and the activity of plasma cathepsin D (p less than 0.005 from SAO vehicle). Taprostene also tended to decrease the accumulation of free amino-nitrogen compounds, but not significantly. In contrast, PGI2 neither improved survival time and the maintenance of post-reperfusion MABP, nor attenuated the rise in hematocrit, the plasma accumulation of free amino-nitrogen compounds, or plasma cathepsin D activity. These findings suggest that taprostene may possess greater cytoprotective properties than PGI2.
Animals↗
Chemical and enzymatic intermediates in the peroxidation of o-dianisidine by horseradish peroxidase. 2. Evidence for a substrate radical--enzyme complex and its reaction with nucleophiles.
Changes in the optical absorption spectrum of horseradish peroxidase, during the oxidation of o-dianisidine at pH 7.5, reveal an intermediate distinct from the previously described compounds I and II. The rate of decay of this new complex appeared to be rate limiting for the catalytic cycle, in this pH range, since imidazole, which augments the catalytic reaction, also enhanced the rate of decay of this complex. Nitrogenous compounds reportedly unable to ligate to hemes, such as 2-methylimidazole and benzimidazole, were nevertheless capable of augmenting the HRP-catalyzed rate of oxidation of o-dianisidine. The activity of nitrogenous compounds, in this regard, appeared to be a function of their nucleophilicity and was sensitive to steric factors but relatively free of a deuterium solvent isotope effect. The data presented in this and in the preceding paper [Claiborne, A., & Fridovich, I. (1979) Biochemistry 18 (preceding paper in this issue)] lead to the suggestion that the nucleophile-responsive intermediate is an enzyme--dianisidine radical complex and that abstraction of the second electron from the bound radical is facilitated by binding of nitrogenous nucleophiles.
Benzidines↗
[Changes in the nitrogen-containing compounds and hydrolysis of proteins in rice grain with different protein content after prolonged storage].
Explore the source record for details and available documents.
Food Preservation↗
Photooxidation mechanism of nitrogen-containing compounds at TiO2/H2O interfaces: an experimental and theoretical examination of hydrazine derivatives.
The photocatalytic oxidation of oxalyldihydrazide, N,N'-bis(hydrazocarbonyl)hydrazide, N,N'-bis(ethoxycarbonyl)hydrazide, malonyldihydrazide, N-malonyl-bis[(N'-ethoxycarbonyl)hydrazide] was examined in aqueous TiO2 dispersions under UV illumination. The photomineralization of nitrogen and carbon atoms in the substrates into N2 gas, NH4+ (and/or NO3-) ions, and CO2 gas was determined by HPLC and GC analysis. The formation of carboxylic acid intermediates also occurred in the photooxidation process. The photocatalytic mechanism is discussed on the basis of the experimental results, and with molecular orbital (MO) simulation of frontier electron density and point charge. Substrate carbonyl groups readily adsorb on the TiO2 surface, and the bonds between carbonyl group carbon atoms and adjacent hydrazo group nitrogen atoms are cleaved predominantly in the initial photooxidation process. The hydrazo groups were photoconverted mainly into N2 gas (in mineralization yields above 70%) and partially to NH4 ions (below 10%). The formation of NO3- ions was scarcely recognized.
Catalysis↗
Nutrient requirements in germination of conidiospores of Aspergillus niger V. Tieghen.
Germination of conidiospores of A. niger was stimulated by the addition of some carbohydrates and nitrogenous compounds to the growth medium. Glucose at 0.5 and 1.0 mg/ml concentrations was the best sugar for germination. Sucrose and fructose were the second best. Glutamic acid and valine were the most effective nitrogenous compounds for the spore germination of the fungus. Glucose, sucrose, and glutamic acid initiated germination within the first 6 h of incubation. When cellobiose, galactose and valine were used germination started after 9 h. With leucine, cysteine and arginine, however, not only the percentage of germination reduced, but also the latent period increased, significantly. A period of 15 h was needed before germination had been started.
Amino Acids↗
Enhancement of cyanobacterial salt tolerance by combined nitrogen.
Presence of certain nitrogenous compounds in the growth medium significantly enhanced the salt tolerance of the fresh-water cyanobacterium Anabaena sp. strain L-31 as well as the brackish water cyanobacterium Anabaena torulosa. Among these, nitrate, ammonium, and glutamine were most effective followed by glutamate and aspartate. These nitrogenous compounds also inhibited Na(+) influx in both Anabaena spp. with the same order of effectiveness as that observed for protection against salt stress. The inhibition of Na(+) influx on addition of the nitrogenous substances was rapid; nitrate and ammonium inhibited Na(+) influx competitively. Proline and glycine did not affect Na(+) influx and also had no influence on the salt tolerance of either Anabaena sp. The observed protection was not consequent to a stimulatory effect of combined nitrogen on growth per se. Uptake of NO(3) (-) and NH(4) (+) increased during salt stress but was not correlated with growth. Intracellular levels of NO(3) (-) and NH(4) (+) were found to be inadequate to constitute a major component of the internal osmoticum. The results suggest that inhibition of Na(+) influx by combined nitrogen is a major mechanism for protection of cyanobacteria against salt stress.
Journal Article↗
[Complex evaluation of nitrogen-containing compounds].
Explore the source record for details and available documents.
Adult↗
Operating problems in anaerobic digestion plants resulting from nitrogen in MSW.
Organic waste and municipal solid waste usually contain considerable amounts of different nitrogen compounds, which may inhibit anaerobic degradation processes and cause problems in the downstream and peripheral devices. This refers particularly to the different process stages of anaerobic digestion, to wastewater treatment, and to exhaust air treatment. Neither the knowledge about nitrogen problems nor the technologies for elimination of nitrogen compounds from the wastewater or the exhaust air of anaerobic digestion can be regarded as state-of-the-art. Most of the technologies in question have already been applied in other areas, but are barely tested for application in anaerobic digestion plants. The few performance data and experiences at hand were mainly derived from pilot and demonstration facilities. In this paper, the problem of nitrogen will be discussed in detail according to the separate problem fields based on the authors' experience, as well as on the basis of a review of the relevant literature. Furthermore, possible solutions will be proposed and the need for further research and development will be formulated.
Bacteria, Anaerobic↗
Effect of uracil on rifamycin SV production by Amycolatopsis mediterranei MV35R.
The effect of different organic nitrogen compounds on the production of rifamycin SV by Amycolatopsis mediterranei MV35R and their optimum concentrations have been described. Results obtained indicate that rifamycin SV production increased from 4020 mg l-1 to 4575 mg l-1 when organic nitrogen compound uracil was added at 0.2% (w/v) concentration to the fermentation medium by A. mediterranei MV35R. The rifamycin SV yield was enhanced by 505 mg l-1 using uracil (2 g l-1) when compared with barbital.
Actinomycetales↗
Nitrogen metabolism in chardonnay musts inoculated with killer strains of Saccharomyces cerevisiae.
This paper examines the evolution of nitrogen compounds during alcoholic fermentation in chardonnay musts inoculated with killer strains of Saccharomyces cerevisiae (ICV D47 and ICV K1M). The results are compared with those obtained from chardonnay must fermented with indigenous yeasts (control sample). The total quantity of nitrogen assimilated, as well as the kinetics of utilization of ammonium ion and amino acids, was different depending on the yeast responsible for the fermentation. In the must inoculated with strain K1M, the nitrogen compounds were consumed more quickly and in greater quantity than in the must inoculated with strain D47. In the uninoculated must, the ammonium ion was not completely consumed, the consumption of amino acids was scant, the fermentation was slow, and the resulting wine had a high volatile acidity. Independently of the yeast used, in all the samples a preference was observed in the consumption of amino acids found in proteins over the amino acids not found in proteins and proline.
Journal Article↗
[Effect of rotting corn straw on the development of bacteria of the Azotobacter group].
The effects of the addition of ground maize straw, nitrogen compounds, ground lucern and water to soils incubated at 30 degrees C in Erlenmeyer flasks, on Azotobacter chroococcum growth have been studied. The results showed that the highest number of Azotobacter in soils treated with different percentage of ground maize straw without addition of nitrogen compounds and with water at 100% field capacity appeared as soon as the 5th day, reaching a maximun on the 20th day when the following numbers of bacteria were observed: control, 1,5 times 20(6); straw 1% 30 times 10(6), 2%, 33 times 10(6) and 4%, 77 times 10(6) per gram of air dried soil. This enables us to assume that the anaerobic decomposition of straw (cellulose and hemicellulose principally) in nature leads to the indirect utilization of its energy for a high asymbiotic microbiogical soil fixation of atmospheric nitrogen.
Azotobacter↗
Does (K+Mg+Ca+P) fertilization lead to recovery of tree health in a nitrogen stressed Quercus rubra L. stand?
In The Netherlands atmospheric deposition of nitrogen compounds to forest ecosystems has been very high for some decades and has led to severe nutritional imbalances in soils as well as in trees. At this moment legislation is not fully in effect with respect to lowering emission/deposition fluxes, particularly of nitrogen. The trees suffer mainly from severe magnesium, potassium and calcium and sometimes phosphorus deficiencies. In this study it was investigated whether fertilization with potassium, magnesium, calcium and phosphorus could prevent a Quercus rubra stand from further decline by restoring the nutritional balance, though the detrimental input of nitrogen compounds still continues. Three fertilization treatments were applied: (i) a standard dose of 1250 kg.ha(-1) containing 60 kg P.ha(-1) (as P2O5), 100 kg K.ha(-1) (as K2O), 80 kg Mg.ha(-1) (as MgO) and 340 kg Ca.ha(-1) (as CaCO3); (ii) two times the standard dose; and (iii) three times the standard dose. Soil solution chemistry showed that the highest dose led to the most significant results: an improved nutrient balance and an increased availability of nutrients. After one growing season following fertilization, the trees looked much healthier and crown density had increased. This revitalization lasted for at least four years. For tree health the mid dose seemed appropriate. After the first growing season potassium is the most mobile nutrient, in the soil and also in the trees, but tended to decrease in the fourth year after fertilization. Magnesium and calcium reached normal values in the leaves after four growing seasons. No obvious effects of phosphorus were found.
Journal Article↗
Identification of genes differentially expressed in extraradical mycelium and ectomycorrhizal roots during Paxillus involutus-Betula pendula ectomycorrhizal symbiosis.
The development of ectomycorrhizal symbiosis leads to drastic changes in gene expression in both partners. However, little is known about the spatial regulation of symbiosis-regulated genes. Using cDNA array profiling, we compared the levels of expression of fungal genes corresponding to approximately 1,200 expressed sequenced tags in the ectomycorrhizal root tips (ECM) and the connected extraradical mycelium (EM) for the Paxillus involutus-Betula pendula ectomycorrhizal association grown on peat in a microcosm system. Sixty-five unique genes were found to be differentially expressed in these two fungal compartments. In ECM, a gene coding for a putative phosphatidylserine decarboxylase (Psd) was up-regulated by 24-fold, while genes coding for urea (Dur3) and spermine (Tpo3) transporters were up-regulated 4.1- and 6.2-fold in EM. Moreover, urea was the major nitrogen compound found in EM by gas chromatography-mass spectrometry analysis. These results suggest that (i) there is a spatial difference in the patterns of fungal gene expression between ECM and EM, (ii) urea and polyamine transporters could facilitate the translocation of nitrogen compounds within the EM network, and (iii) fungal Psd may contribute to membrane remodeling during ectomycorrhiza formation.
Basidiomycota↗
Condensation reactions and formation of amides, esters, and nitriles under hydrothermal conditions.
Hydrothermal pyrolysis experiments were performed to assess condensation (dehydration) reactions to amide, ester, and nitrile functionalities from lipid precursors. Beside product formation, organic compound alteration and stability were also evaluated. Mixtures of nonadecanoic acid, hexadecanedioic acid, or hexadecanamide with water, ammonium bicarbonate, and oxalic acid were heated at 300 degrees C for 72 h. In addition, mixtures of ammonium bicarbonate and oxalic acid solutions were used to test the abiotic formation of organic nitrogen compounds at the same temperature. The resulting products were condensation compounds such as amides, nitriles, and minor quantities of N-methylalkyl amides, alkanols, and esters. Mixtures of alkyl amide in water or oxalic acid yielded mainly hydrolysis and dehydration products, and with ammonium bicarbonate and oxalic acid the yield of condensation products was enhanced. The synthesis experiments with oxalic acid and ammonium bicarbonate solutions yielded homologous series of alkyl amides, alkyl amines, alkanes, and alkanoic acids, all with no carbon number predominances. These organic nitrogen compounds are stable and survive under the elevated temperatures of hydrothermal fluids.
Amides↗
Oral administration of biochemically active microcapsules to treat uremia: new insights into an old approach.
This paper begins with an extensive review of previous research on the degradation of non-protein nitrogen compounds for improved therapy of renal failure. During the 1970s, Malchesky established that naturally occurring strains of microorganisms were highly effective for the in vitro degradation of urea and other compounds found in urine, and that these bacteria could be conditioned with selected media to enhance growth and degradation efficiency. A few years later, Setala introduced the concept of oral delivery of lyophilized bacteria, harvested from soil, to uremic patients, for degradation of non-protein nitrogen compounds. In the 1990s, Chang proposed delivery of encapsulated genetically modified bacteria for removal of uremic waste products in vitro and in vivo. Recently, our group has pursued the idea of orally delivering formulated combinations of enzymes or modified bacteria. A new study is also described, which characterizes the capacity of a single alginate microcapsule containing a mixture of genetically modified cells and enzyme to degrade urea, uric acid and creatinine. The combination capsules were found to be effective in vitro and in vivo in a rodent model of chemically-induced renal failure. Reduction of urea concentration in vivo required co-administration of a cation exchange resin to adsorb ammonia. Increased investigative effort is warranted for these approaches which offer significant potential as an adjunct to conventional forms of dialysis.
Administration, Oral↗