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At least 127 records · Page 7Linked to original sources
PubMedDate not supplied

Maternal exposure to exogenous nitrogen compounds and complications of pregnancy.

Increased lipid peroxidation and reduced antioxidant activity have been reported with pregnancy complications. Given that exogenous oxidants stimulate formation of lipid peroxides, the authors investigated the relationship between exposure to nitrogen-oxidizing species and pregnancy complications and took into account markers of antioxidant and oxidant status. The study sample included pregnant women who were from an area polluted by oxidized nitrogen compounds. Methemoglobin, a biomarker of individual exposure, was determined, as were measures of oxidant/antioxidant status, including glutathione balance and lipid peroxide levels. Only 10 women experienced normal pregnancies. The most common complications were anemia (67%), threatened abortion/premature labor (33%), and signs of preeclampsia (23%). Methemoglobin was elevated significantly in all three conditions, compared with normal pregnancies. Reduced:total glutathione decreased, whereas lipid peroxide levels increased. These results suggest that maternal exposure to environmental oxidants can increase the risk of pregnancy complications through stimulation of the formation of cell-damaging lipid peroxides and from a decrease in maternal antioxidant reserves.

Adult↗
PubMed1986

Net absorption of glucose, L-lactate, volatile fatty acids, and nitrogenous compounds by bovine given abomasal infusions of starch or glucose.

Three experiments were conducted to evaluate effects of abomasal infusion of glucose or starch on absorption of metabolites (glucose, L-lactate, volatile fatty acids, and nitrogenous compounds) from portal-drained viscera of a nonlactating Holstein cow and two Hereford X Angus heifers. Portal blood and plasma flow were determined by dilution of para-aminohippuric acid. Net absorption was portal-arterial concentration difference times portal plasma flow. Plasma concentration and portal-arterial difference of glucose increased rapidly and directly in response to increased rates of abomasal glucose infusion in the cow (Experiment 1). In the cow (Experiment 2), net absorption of L-lactate was greater with carbohydrate than with water infusion; net absorption of L-lactate was greater and of n-butyrate was less with starch than with glucose infusion. These responses were not evident in the heifers (Experiment 3). Net absorption of alpha-amino-N in the heifers was greater with starch than with glucose infusion. Increased concentrate intake by the heifers did not interact with responses to abomasal infusions. Recovery of infused glucose as absorbed glucose was similar for the cow and the heifers (65%). However, heifers absorbed (as glucose) 35% of infused starch and the cow only 8%.

Abomasum↗
PubMed2005

HPLC determination of free nitrogenous compounds of Centaurea solstitialis (Asteraceae), the cause of equine nigropallidal encephalomalacia.

Centaurea solstitialis (yellow star thistle) has been proven to cause equine nigropallidal encephalomalacia in horses. Over the last fifty years, nigropallidal encephalomalacia has been of interest to human medicine due to the possible connection with Parkinson's disease. Previous studies indicated the presence of neurotoxic nitrogenous compounds in polar extracts of the plant. In order to give a more detailed description of the nitrogen-containing fraction of C. solstitialis, various samples were collected at different development stages. Different aliquots of the same aqueous extract were directly derivatized with o-phthaldialdehyde and dansyl chloride and analyzed separately by reversed-phase HPLC. A complete profile of the free nitrogenous fraction of C. solstitialis was given and results obtained with the two derivatization procedures were compared. No particularly high level of free aspartic and glutamic acids, two potent neuroexcitotoxic amino acids, were found in polar extracts of the plant. Tyramine resulted to be the most important biologically active amine present in C. solstitialis (with a mean concentration of 2.0 mg/100 g of dry weight).

Amino Acids↗
PubMed1988

Partition of portal-drained visceral net flux in beef steers. 1. Blood flow and net flux of oxygen, glucose and nitrogenous compounds across stomach and post-stomach tissues.

1. Blood from chronic indwelling catheters in the caudal aorta and anterior mesenteric, gastrosplenic and hepatic portal veins was used to measure blood flow and net flux of oxygen, glucose and nitrogenous compounds across hepatic portal-drained viscera (PDV), post-stomach (anterior mesenteric-drained viscera (MDV] and stomach tissues of two beef steers (390 kg mean live weight). 2. Steers were fed in sequence on (1) chopped lucerne (Medicago sativa) hay (twelve meals/d), (2) chopped lucerne hay (two meals/d) and (3) a pelleted concentrate diet containing 780 g ground maize/kg (two meals/d). The lucerne hay and concentrate contained 26.5 and 16.8 g nitrogen/kg respectively. 3. Five measurements of net flux (blood flow multiplied by venous-arterial concentration differences (VA] were obtained hourly on 2 d for each dietary regimen, beginning 0.5 h before feeding at 08.00 hours. Blood flow was measured by downstream dilution of p-aminohippurate (PAH). 4. Blood flow across MDV averaged 42% of PDV blood flow (665 litres/h). 5. Net use of O2 across MDV accounted for 51% of net PDV use of O2 (920 mmol/h). This disproportionate use of O2 in relation to blood flow was due to greater VA for O2 across MDV than across stomach tissues. Dietary regimen had no effect on the proportions of PDV blood flow and net O2 consumption attributable to MDV or stomach tissues. 6. When lucerne was given, net glucose use across MDV represented 69% of PDV use (35 mmol/h). When concentrate was given, MDV glucose use switched to net absorption (29 mmol/h), reducing net PDV glucose use to 1 mmol/h. 7. When concentrate was given, net MDV absorption of alpha-amino-N (AAN) increased from 98 to 190 mmol/h, yet net PDV absorption (101 mmol/h) was not affected. Net stomach AAN flux increased from -7 to -69 mmol/h when concentrate was given, negating the increase in net MDV absorption. 8. Net absorption of ammonia-N across MDV represented 28 and 52% of net PDV absorption when lucerne and concentrate were given respectively. Net NH3-N absorption across PDV was lower when lucerne was given than when concentrate was given (295 v. 154 mmol/h), reflecting lower dietary N intake (153 v. 83 g/d). Net MDV absorption of NH3-N was not affected by diet. Net removal of blood urea-N (BUN) across PDV (101 mmol/h) was not affected by diet. Across MDV, BUN removal was lower when concentrate was given than when lucerne was given (32 v. 77 mmol/h).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

Interaction of 2-hydroxy-substituted Nile red fluorescent probe with organic nitrogen compounds.

The fluorescent properties of 2-hydroxy Nile red dye (HONR) proved to be highly sensitive to the basicity of hydrogen bond acceptors. Fluorescence quantum yields and fluorescence decay profiles were measured as the function of the concentration of organic nitrogen compounds in solvents of various polarities. The detailed mechanism and the kinetics of the fluorescence quenching were revealed with the combined analysis of the steady-state and time-resolved spectroscopic data. The relative contribution of the competing reaction steps was found to be very sensitive to the basicity of the additive and to solvent polarity. The most profound change appeared in the unimolecular deactivation pathways of the excited hydrogen-bonded HONR, whereas the formation rate of this species varied to a lesser extent. The dissociation into excited HONR and ground-state base was able to compete with the energy dissipation only when 2,4,6-trimethylpyridine was used as hydrogen bond acceptor in toluene. The bimolecular quenching of the excited hydrogen-bonded complex played significant role in apolar solvents. Proton displacement along the hydrogen bond in the excited complex led to excited ion pairs in polar media.

Aminopyridines↗
PubMed1997

Removal of nitrogenous compounds by catalytic wet air oxidation. Kinetic study.

Aqueous wastes containing organic pollutants can be efficiently treated by wet air oxidation (WAO), i.e. oxidation by molecular oxygen in the liquid phase, under high temperature (200-325 degrees C) and pressure (up to 150 bar). However, organic nitrogen can be relatively resistant to oxidation and can be harmful to the environment. In the course of treatment, organic nitrogen (N-Org) is converted into ammonia (NH(3)), while organic carbon (C-Org) is converted mainly into carbon dioxide (CO(2)). This can be done without catalysts. In the presence of Mn/Ce composite oxides, it is possible to transform ammonia into molecular nitrogen at a temperature close to 260 degrees C. The direct conversion of organic nitrogen into molecular nitrogen also can be achieved using the same catalyst. This paper discusses the results obtained during the treatment of nitrogenous compounds like aniline, nitrophenol, beta-alanine and ammonia. Laboratory investigations were conducted in a stirred batch reactor with Mn/Ce composite oxides as catalysts. Very limited amounts of nitrites and nitrates were observed with amines, but more significant quantities were found with nitro-compounds. The kinetics of oxidation of ammonia, organic compounds, and more particularly aniline, were investigated. The treatment of a real waste (process wastewater) was also investigated. The dependence of the transformation rate on various parameters (amount of catalyst, temperature, etc.) was established. The rates of oxidation are described by first-order kinetic laws with respect to the various nitrogen species (aniline, NH(3)). Several parallel pathways are considered for the transformation of organic nitrogen, amongst which is an interaction with the catalyst surface. The orders with respect to oxygen and catalyst are established.

Journal Article↗
PubMed2004

Study of a three-stage fluidized bed process treating acrylic synthetic-fiber manufacturing wastewater containing high-strength nitrogenous compounds.

Polyacrylonitrile (PAN) is one of the major synthetic fibers commonly used in the mass production of clothing. The chemical synthesis of PAN is carried out by polymerization of the acrylonitrile (AN) monomers with co-monomers such as vinyl acetate, methyl acrylate and cyclohexyl acrylate. Using water quality analysis of the PAN wastewater, high concentration of organic nitrogen was found and the TKN/COD ratios achieved were 0.15-0.26, indicating the complicated biodegradation characteristics for the PAN wastewater. In order to enhance biodegradation of nitrogenous compounds in PAN wastewater, a combined three-stage process of thermophilic anaerobic/anoxic denitrification/aerobic nitrification fluidized bed reactors was employed. The results indicated that the concentration of effluent in the three-stage process of OD and organic nitrogen was 175 mg/L and 13 mg/L, respectively. Furthermore, molecular biotechnology was applied to study the microbial population in the thermophilic anaerobic fluidized bed reactor. From the results of denaturing gradient gel electrophoresis, the diversity of PAN-degrading bacteria would change in different volumetric loading. Furthermore, the bacteria communities in the thermophilic anaerobic fluidized bed reactor were also studied by fluorescence in situ hybridization and confocal laser scanning microscopy. Alpha and delta-Proteobacteria were dominant in the bacteria population, and some high G+C content bacteria and Clostridium could be characterized in this system.

Acrylic Resins↗
PubMedDate not supplied

[Effect of the physiological properties of yeast strains on their formation of higher alcohols and aldehydes and on the composition of nitrogen compounds in the fermented wort].

Dynamics of formation of by-products was studied with the following yeast races: Sacch. cerevisiae, strain Odesskaya-14 (baker's yeast); Sacch. vini, strain Prikumskaya 80/9 (wine yeast). The yeast cultures were found to be very similar by the rate of biomass accumulation, ethanol production, and the fractional composition of nitrogen compounds. The concentration of accumulated higher alcohols depended on the mass of yeast cells, their growth rate, and the duration of cultivation.

Aldehydes↗
PubMed2003

Cementation reactions in the presence of nitrogen compounds.

The effect of aniline derivatives on the rate of cementation of copper from dilute copper sulfate solution on iron rods was investigated. The variables studied were concentration of CuSO(4), temperature, organic additives, and their concentrations. It was found that the cementation reaction was first-order in the presence and in the absence of additives. Nitrogen compounds were found to decrease the rate of cementation by 10 to 80% depending on the type of inhibitor as well as its concentration.The adsorption isotherm, the effect of temperature, and the percentage inhibition show that the order of inhibition is p-chloroaniline>o-chloroaniline>m-chloroaniline and p-chloroaniline>p-aminobenzoic acid>p-aminoacetophenone. The thermodynamic parameters DeltaS( not equal ), DeltaG( not equal ), DeltaH( not equal ) were given.

Journal Article↗
PubMed1988

Cellular location of asparaginase activity in Saccharomyces cerevisiae and regulation of this activity by nitrogen compounds.

Three asparaginase activities have been detected in Saccharomyces cerevisiae. One is found outside the permeability barrier; a second one is found inside and is soluble in the cell, and the third one is localized in a system of membrane particles. Synthesis of the membrane and external asparaginases require "de novo" synthesis of RNA and protein. The synthesis of exocellular asparaginase is inhibited by several nitrogen compounds (catabolite repression). This inhibition might take place at the transcriptional level. Moreover, this isoenzyme is reversibly inactivated by its natural substrates (catabolite inhibition by substrates). The half life of external asparaginase mRNA was calculated by two independent methods and values of 7.5 and 9.5 min were found.

Asparaginase↗
PubMedDate not supplied

Sources and transformations of nitrogen compounds along the Lower Jordan River.

The Lower Jordan River is located in the semiarid area of the Jordan Valley, along the border between Israel and Jordan. The implementation of the water sections of the peace treaty between Israel and Jordan and the countries' commitment to improve the ecological sustainability of the river system require a better understanding of the riverine environment. This paper investigates the sources and transformations of nitrogen compounds in the Lower Jordan River by applying a combination of physical, chemical, isotopic, and mathematical techniques. The source waters of the Lower Jordan River contain sewage, which contributes high ammonium loads to the river. Ammonium concentrations decrease from 20 to 0-5 mg N L(-1) along the first 20 km of the Lower Jordan River, while nitrate concentrations increase from nearly zero to 10-15 mg N L(-1), and delta(15)N (NO(3)) values increase from less than 5 per thousand to 15-20 per thousand. Our data analysis indicates that intensive nitrification occurs along the river, between 5 and 12 km from the Sea of Galilee, while further downstream nitrate concentration increases mostly due to an external subsurface water source that enters the river.

Environmental Monitoring↗
PubMed2002

An evaluation of the UAM-V predicted concentrations of carbon monoxide and reactive nitrogen compounds over the eastern United States during summer 1995.

While there is a clear need to evaluate a photochemical model's ability in predicting not only the concentrations of O3, but also precursors and other trace species, many previous studies have focused only on the assessment of During the 1995 summer season, in addition to the routine monitoring of criteria pollutants, several research-oriented monitoring campaigns were conducted over the eastern United States, providing an extensive database of reactive nitrogen compounds, CO, and speciated hydrocarbon data. In this study, we examine the ability of a photochemical modeling system, RAMS/ UAM-V, to reproduce the measured concentrations of CO, NO2, and NOy over the region during the summer of 1995. The results demonstrate that there is agreement between modeled and measured seasonal average concentrations of NO2, both at the routine and research monitors. The same is true for NOy, but to a lesser degree. However, the model is found to significantly underpredict CO for the routine monitors in comparison to the research monitors.

Air Pollutants↗
PubMed1987

Effects of additives and thermal treatment on the content of nitrogen compounds and the nutritive value of hake meat.

Heating of minced meat from 40 to 130 degrees C for 10 min and at 120 degrees C from 15 to 60 min with potato starch (3%), soya oil (4%), salt (1.5%), and water (15%) resulted in a decrease in total amino-acid content by 6% on the average, compared to the content in meat without additives. Heating time-dependent changes involved a decrease in the lysine content, while temperature-dependent changes involved a decrease in the valine content. On the other hand, the presence of additives reduced the thermal protein hydrolysis towards the formation of low-molecular nitrogen compounds. Prolonged time of heating of minced hake meat at 120 degrees C produced a more intensive protein hydrolysis than a shorter heating up to 130 degrees C; at the same time with temperatures exceeding 100 degrees C an intensive increase in the ammonia content, decrease in -SH groups content, and a decrease in protein digestibility were observed.

Amino Acids↗
PubMed2002

High-pressure syntheses of novel binary nitrogen compounds of main group elements.

The application of high-pressure methods in the search for novel materials usually requires additional effort compared to syntheses at ambient pressure. Depending on the desired p/T conditions different methods may be used. Special techniques and experimental apparatus such as shock waves, diamond anvil cells, and multianvil presses, which have been applied mainly by earth scientists and physicists in the past, are increasingly being applied by synthetic chemists and material scientists. A series of fascinating discoveries have been made recently as is demonstrated by three examples of binary nitrogen compounds: 1) Diazenides, compounds with N(2)(2-) ions, were obtained as single-phase products and structurally characterized for the first time. 2) At 11 GPa and 1800 K a phosphorus(V) nitride was prepared, which contains tetragonal PN(5) pyramids as a novel structural motif. 3) Macroscopic amounts of spinel silicon nitride were synthesized by shock-wave techniques, which allows the comprehensive characterization and possibly the implementation of this new hard material.

Journal Article↗
PubMed1975

Deamination of biogenic amines and other nitrogenous compounds in granulation tissue from experimental wounds.

In the granulation tissue of skin wounds an increase in the content of hydroxyproline was accompanied by changes in lipid peroxidation products. At the same time deamination of 5-hydroxytryptamine, tyramine or adenosine-5'-monophosphate decreased, but the ability to deaminate histamine, putrescine and lysine appeared. Pargyline prevented the appearance of these new deaminating properties. Adenosine-3'-monophosphate slowed down to the weight increase and lowered the content of hydroxyproline in the growing granulation tissue; it also changed the dynamics of deamination of tyramine or 5-hydroxytryptamine and significantly inhibited the deamination of histamine, lysine and adenosine-5'-monophosphate. The patterns of changes in deamination of nitrogenous compounds and the effects caused by pargyline and adenosine-3'-monophosphate suggest that qualitative alteration (transformation) in catalytic properties of monoamine oxidases may occur in the growing granulation tissue from wounds.

Adenosine Monophosphate↗