PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “NITROGEN AND 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.

At least 73 records · Page 4Linked to original sources
PubMed2002

The reactivity of Mo(PMe3)(6) towards heterocyclic nitrogen compounds: transformations relevant to hydrodenitrogenation.

The reactions of Mo(PMe3)6 towards a variety of five- and six-membered heterocyclic nitrogen compounds (namely, pyrrole, indole, carbazole, pyridine, quinoline, and acridine) have been studied to provide structural models for the coordination of these heterocycles to the molybdenum centers of hydrodenitrogenation catalysts. Pyrrole reacts with Mo(PMe3)6 to yield the eta5-pyrrolyl derivative (eta5-pyr)Mo(PMe3)3H, while indole gives sequentially (eta1-indolyl)Mo(PMe3)4H, (eta5-indolyl)Mo(PMe3)3H, and (eta6-indolyl)Mo(PMe3)3H, with the latter representing the first example of a structurally characterized complex with an eta6-indolyl ligand. Likewise, carbazole reacts with Mo(PMe3)6 to give (eta6-carbazolyl)Mo(PMe3)3H with an eta6-carbazolyl ligand. The reactions of Mo(PMe3)6 with six-membered heterocyclic nitrogen compounds display interesting differences in the nature of the products. Thus, Mo(PMe3)6 reacts with pyridine to give an eta2-pyridyl derivative [eta2-(C5H4N)]Mo(PMe3)4H as a result of alpha-C-H bond cleavage, whereas quinoline and acridine give products of the type (eta6-ArH)Mo(PMe3)3 in which both ligands coordinate in an eta6-manner. For the reaction with quinoline, products with both carbocyclic and heterocyclic coordination modes are observed, namely [eta6-(C6)-quinoline]Mo(PMe3)3 and [eta6-(C5N)-quinoline]Mo(PMe3)3, whereas only carbocyclic coordination is observed for acridine.

Journal Article↗
PubMed1979

Nitrogenous compounds reversibly inhibit the adenosine 3',5'-monophosphate response to thyrotropin: this effect is dissociated from altered guanine 3',5'-monophosphate levels.

Nitrogenous compounds were studied for their effect on cGMP levels in the thyroid. Several agents, including sodium nitrite and hydroxylamine, could generate a rise of over 100-fold in cGMP. At a concentration of 20 mM, HN2OH and NaNO2 significantly reduced cAMP levels previously generated by 0.5 mU/ml TSH. If the slices were rinsed and placed in new buffer without the latter nitrogenous compound, the cAMP response to TSH was restored even though intracellular cGMP levels remained elevated. Thus, the counterregulatory effect of these agents on cAMP levels is not correlated with the presence of high levels of cGMP per se. Both the rise in cGMP and the fall in cAMP could still be detected when Ca++ was deleted from the incubation medium, in contrast to other reported stimuli that elevate cGMP levels in the thyroid.

Animals↗
PubMed1998

Expression of an arabidopsis aspartate Kinase/Homoserine dehydrogenase gene is metabolically regulated by photosynthesis-related signals but not by nitrogenous compounds

Although the control of carbon fixation and nitrogen assimilation has been studied in detail, relatively little is known about the regulation of carbon and nitrogen flow into amino acids. In this paper we report our study of the metabolic regulation of expression of an Arabidopsis aspartate kinase/homoserine dehydrogenase (AK/HSD) gene, which encodes two linked key enzymes in the biosynthetic pathway of aspartate family amino acids. Northern blot analyses, as well as expression of chimeric AK/HSD-beta-glucuronidase constructs, have shown that the expression of this gene is regulated by the photosynthesis-related metabolites sucrose and phosphate but not by nitrogenous compounds. In addition, analysis of AK/HSD promoter deletions suggested that a CTTGACTCTA sequence, resembling the binding site for the yeast GCN4 transcription factor, is likely to play a functional role in the expression of this gene. Nevertheless, longer promoter fragments, lacking the GCN4-like element, were still able to confer sugar inducibility, implying that the metabolic regulation of this gene is apparently obtained by multiple and redundant promoter sequences. The present and previous studies suggest that the conversion of aspartate into either the storage amino acid asparagine or aspartate family amino acids is subject to a coordinated, reciprocal metabolic control, and this biochemical branch point is a part of a larger, coordinated regulatory mechanism of nitrogen and carbon storage and utilization.

Journal Article↗
PubMed2000

Expression of threonine synthase from Solanum tuberosum L. is not metabolically regulated by photosynthesis-related signals or by nitrogenous compounds.

Although the control of carbon fixation and nitrogen assimilation has been studied in detail, little is known about the regulation of carbon and nitrogen flow into amino acids. In this paper the isolation of a cDNA encoding threonine synthase is reported (TS; EC 4.2.99.2) from a leaf lambda ZAP II-library of Solanum tuberosum L. and the transcriptional regulation of the respective gene expression in response to metabolic changes. The pattern of expression of TS by feeding experiments of detached petioles revealed that TS expression is regulated neither by photosynthesis-related metabolites nor by nitrogenous compounds. The present study suggests that the regulation of the conversion of aspartate to threonine is not controlled at the transcript level of TS. The nucleotide and deduced amino acid sequences of potato TS show homology to other known sequences from Arabidopsis thaliana and microorganisms. TS is present as a low copy gene in the genome of potato as demonstrated in Southern blot analysis. When cloned into a bacterial expression vector, the cDNA did functionally complement the Escherichia coli mutant strain Gif41. TS transcript was found in all tissues of potato and was most abundant in flowers and source leaves.

Journal Article↗
PubMed1986

Ammonia production and its contribution to urinary nitrogenous compounds in chickens fed low or high protein diet.

The rates of total ammonia production and of ammonia retention and contribution of endogenous ammonia to urinary nitrogenous compounds were assessed using a constant intravenous infusion method with [15N]ammonia for 6 h in adult cockerels fed 7.00 or 1.75 g of protein per kilogram body weight per day for 5 d. At the 7.00-g protein intake level the mean total body ammonia production rate was 47.1 mumol/kg per min, with total excretion and retention rates being 10.1 mumol/kg per min and 37.0 mumol/kg per min, respectively. In birds with 1.75 g protein intake the mean total body ammonia production rate was 27.9 mumol/kg per min, with total excretion and retention rates being 3.1 mumol/kg per min and 24.8 mumol/kg per min, respectively. These values were significantly different between the two dietary groups (P less than 0.05-0.01). Ammonia N produced at low and high levels of dietary protein intake, contributed 33% and 84% of urinary uric acid N and 27% and 58% of urinary total N, respectively. With the above protein intake levels, 88% of urinary ammonia N and 6-9% of urinary nitrogenous compounds other than ammonia and uric acid were donated by ammonia N produced in the body. It is concluded that ammonia N produced in the body is the main source of uric acid N, which entirely explains the increase in urinary total N caused by feeding a high protein diet.

Ammonia↗
PubMed1999

Use of nitrogen compounds in spontaneous and inoculated wine fermentations.

In this paper the use of nitrogen compounds in garnacha must inoculated with active dry wine yeast Saccharomyces cerevisiae subsp. cerevisiae strain Na33 has been studied. The results are compared to garnacha must fermented with indigenous yeasts (control must). In the samples where the inoculated yeast predominated, no qualitative differences were appreciated in the use of amino acids with respect to the control samples, although there were quantitative differences. In the musts where the Na33 strain dominated, a lesser quantity of amino acids were consumed at the beginning of fermentation than in the control samples. For that reason, probably, this yeast showed problems in competing for the nitrogen nutrients of the must; this could have made its implantation in one of the inoculated samples more difficult. At the end of fermentation the Na33 strain continued to consume amino acids at high concentrations of ethanol. Its high tolerance to this toxic could be favored by the production and rehydration of dry wine yeast in the presence of air.

Amino Acids↗
PubMed2003

Health implications of exposure to environmental nitrogenous compounds.

All living systems need nitrogen for the production of complex organic molecules, such as proteins, nucleic acids, vitamins, hormones and enzymes. Due to the intense use of synthetic nitrogen fertilisers and livestock manure in modern day agriculture, food (particularly vegetables) and drinking water may contain higher concentrations of nitrate than in the past. The mean intake of nitrate per person in Europe is about 50-140 mg/day and in the US about 40-100 mg/day. In the proximal small intestine, nitrate is rapidly and almost completely absorbed (bioavailability at least 92%). In humans, approximately, 25% of the nitrate ingested is secreted in saliva, where some 20% (about 5-8% of the nitrate intake) is converted to nitrite by commensal bacteria. The nitrite so formed is then absorbed primarily in the small intestine. Nitrate may also be synthesised endogenously from nitric oxide (especially in case of inflammation), which reacts to form nitrite. Normal healthy adults excrete in the urine approximately 62 mg nitrate ion/day from endogenous synthesis. Thus, when nitrate intake is low and there are no additional exogenous sources (e.g. gastrointestinal infections), the endogenous production of nitrate is more important than exogenous sources. Nitrate itself is generally regarded nontoxic. Toxicity is usually the result of the conversion of nitrate into the more toxic nitrite. There are two major toxicological concerns regarding nitrite. First, nitrite may induce methaemoglobinaemia, which can result in tissue hypoxia, and possibly death. Secondly, nitrite may interact with secondary or N-alkyl-amides to form N-nitroso carcinogens. However, epidemiological investigations and human toxicological studies have not shown an unequivocal relationship between nitrate intake and the risk of cancer. The Joint Expert Committee of the Food and Agriculture Organization of the United Nations/World Health Organization (JECFA) and the European Commission's Scientific Committee on Food have set an acceptable daily intake (ADI) for nitrate of 0-3.7 mg nitrate ion/kg bodyweight; this appears to be safe for healthy neonates, children and adults. The same is also true of the US Environmental Protection Agency (EPA) Reference Dose (RfD) for nitrate of 1.6 mg nitrate nitrogen/kg bodyweight per day (equivalent to about 7.0 mg nitrate ion/kg bodyweight per day). This opinion is supported by a recent human volunteer study in which a single dose of nitrite, equivalent to 15-20 times the ADI for nitrate, led to only mild methaemoglobinaemia (up to 12.2%), without other serious adverse effects. The JECFA has proposed an ADI for nitrite of 0-0.07 mg nitrite ion/kg bodyweight and the EPA has set an RfD of 0.1 mg nitrite nitrogen/kg bodyweight per day (equivalent to 0.33 mg nitrite ion/kg bodyweight per day). These values are again supported by human volunteer studies.

Animals↗
PubMed2006

A new high-nitrogen compound [Mn(ATZ)(H2O)4] x 2H2O: synthesis and characterization.

A new high-nitrogen compound [Mn(ATZ)(H(2)O)(4)] x 2H(2)O (ATZ=5,5-azotetrazolate) was synthesized. Crystal structure and elemental, IR and thermal analyses were investigated in the present work. It crystallized in triclinic space group P-1 with lattice parameters a=6.304(2)A, b=7.004(2)A, c=7.921(3)A, alpha=76.114(5) degrees , beta=74.023(5) degrees , gamma=69.254(4) degrees . TG-DTG and DSC measurements are employed to postulate the thermal decomposition mechanism. The thermal decomposition kinetics of the main exothermic reaction was investigated by non-isothermal method and obtained its enthalpy of decomposition and the probable kinetic mechanism. An attempt was made to incorporate the relation between thermal stability and the structure.

Crystallography, X-Ray↗
PubMed1987

Net absorption from portal-drained viscera of nitrogenous compounds by beef heifers fed on diets differing in protein solubility or degradability in the rumen.

The objective of the present study was to evaluate effects of in vitro rumen solubility or degradability of dietary protein on net absorption of nitrogenous compounds from portal-drained viscera of beef heifers. Four protein sources, casein, soya-bean meal, maize-gluten meal and blood meal provided about two-thirds of total dietary nitrogen in semi-purified diets given to four beef heifers in a 4 X 4 Latin square design. Although in vitro degradability of dietary N ranged from 842 (casein) to 310 (blood meal) g/kg total dietary N, net absorption of ammonia-N or alpha-amino-N was not significantly different (P greater than 0.10) among diets. However, net absorption of NH3-N tended to decrease and net absorption of alpha-amino-N tended to increase as intake of in vitro undegradable N increased. Net transfer of urea-N from plasma to portal-drained viscera was greater (P less than 0.10) when heifers were fed on soya-bean meal than when fed on maize-gluten meal or blood meal. The findings show with all diets that the non-protein-nitrogenous compounds, NH3 and urea, played a substantial role in absorption and transfer of N. Overall, net absorption of NH3-N was 61% of net absorption of alpha-amino-N, and transfer of urea-N from plasma to portal-drained viscera was 80% of net absorption of alpha-amino-N.

Animals↗
PubMedDate not supplied

[Features of the biochemical action of paraquat on oxidative deamination of biogenic amines and other nitrogen compounds].

Intoxication of rats with the herbicide paraquat (1,1-dimethyl-4,4-bipyridilium dichloride) was accompanied by accumulation in lungs, brain, heart, liver or kidney of malonic dialdehyde (MDA) (the compounds reacting with 2-thiobarbituric acid), indicating that the intoxication stimulated lipid peroxidation (LPO) in biomembranes. Treatment of the intoxicated rats with the antioxidant diludin (2,6-dimethyl-3,5-diethoxycarbonyl-1,4-dihydropyridine) or with the nucleophilic reagents sodium ascorbate or thiosulphate normalized the content of MDA in lungs, brain, heart, liver or kidney demonstrating the reversibility of the LPO stimulation caused by paraquat. On incubation of mitochondrial fractions of homogenates of lungs, brain, heart, liver or kidney of the intoxicated rats (as compared with the corresponding fractions from the intact animals) a decrease was noted in deamination of the substrates of monoamine oxidases serotonin, tryptamine, benzylamine, tyramine; at the same time, deamination of glucosamine and gamma-aminobutyric acid was increased and deamination of putrescine and L-lysine appeared. These impairments in deamination of nitrogenous compounds caused by paraquat were reversible. All the impairments were normalized by the treatment of the experimental animals with the antioxidative and nucleophilic reagents; a decrease was noted in the rate of development of the lethal paraquat intoxication and appearance of morphological manifestations of normalization. The data obtained suggest that the reversible, qualitative modification ("transformation") of the monoamine oxidases of the type A might explain the peculiarities of the alterations in deamination of nitrogenous compounds in paraquat intoxication.

Amination↗
PubMed2005

Oxidative stress protection by newly synthesized nitrogen compounds with pharmacological potential.

In this study we used new nitrogen compounds obtained by organic synthesis whose structure predicted an antioxidant potential and then an eventual development as molecules of pharmacological interest in diseases involving oxidative stress. The compounds, identified as FMA4, FMA5, FMA7 and FMA8 differ in the presence of hydroxyl groups located in the C-3 and/or C-4 position of a phenolic unit, which is possibly responsible for their free radicals' buffering capacity. Data from the DPPH discoloration method confirm the high antiradical efficiency of the compounds. The results obtained with cellular models (L929 and PC12) show that they are not toxic and really protect from membrane lipid peroxidation induced by the ascorbate-iron oxidant pair. The level of protection correlates with the drug's lipophilic profile and is sometimes superior to trolox and equivalent to that observed for alpha-tocopherol. The compounds FMA4 and FMA7 present also a high protection from cell death evaluated in the presence of a staurosporine apoptotic stimulus. That protection results in a significant reduction of caspase-3 activity induced by staurosporine which by its turn seems to result from a protection observed in the membrane receptor pathway (caspase-8) together with a protection observed in the mitochondrial pathway (caspase-9). Taken together the results obtained with the new compounds, with linear chains, open up perspectives for their use as therapeutical agents, namely as antioxidants and protectors of apoptotic pathways. On the other hand the slight pro-oxidant profile obtained with the cyclic structures suggests a different therapeutic potential that is under current investigation.

Animals↗
PubMed1984

[Disorders of the deamination of nitrogenous compounds in the heart muscle in experimental atherosclerosis].

The development of alimentary hypercholesterolemia in rabbits (confirmed by morphometric, electrophysiological and biochemical data) was accompanied by a decrease of the serotonin, benzylamine and tyramine deamination rates in heart muscle mitochondria. At the same time a qualitatively new reaction of cadaverine deamination could be seen in the mitochondria. The data obtained suggest that impairment of deamination of the nitrogenous compounds in atherosclerosis may be due to reversible qualitative modification (transformation) of mitochondrial monoamine oxidase activity. Some of the drugs which decrease the level of lipids in blood serum of hypercholesterolemic rabbits abolished and prevented the impairment of deamination of nitrogenous compounds.

Animals↗
PubMed2004

Ion-exchange resins in the isolation of nitrogen compounds from petroleum residues.

In this work, preparative liquid chromatography was used for the separation of the nitrogen compounds in a sample of heavy gas oil from a Brazilian petroleum. Initially it took place a pre-fractionation by neutral aluminium oxide and the compounds were separated in different classes such as: hydrocarbons, resins (compounds of low molecular mass and intermediate polarity) and asphalthenes (polar compounds with high molecular mass). A comparison of the fraction of resins was performed by re-fractionating with modified silica (with potassium hydroxide and hydrochloric acid), or with ion exchange resins (Amberlyst A-27 and A-15), being isolated the basic and neutral compounds, that were analyzed by GC-MS in the scan and selected ion monitoring modes. Quinolines, benzoquinolines, tetrahydroquinolines were found in the basic fraction and carbazoles derivatives were found in the neutral fraction.

Gas Chromatography-Mass Spectrometry↗
PubMed2001

Deposition of atmospheric nitrogen compounds in humid tropical Cuba.

Acid deposition, a direct effect of gaseous air pollutants, is causing widespread damage to terrestrial and aquatic ecosystems. Further, these pollutants are responsible for the corrosion of building materials and cultural objects, as well as having an impact on human health. In Cuba, main atmospheric deposition of nitrogen compounds varies from approximately 12.0 to 65.0 kg N ha(-1) year(-1) in rural areas. Ammonia and ammonium are the most important elements in Cuba's tropical conditions.

Air Pollutants↗
PubMedDate not supplied

[Deamination reactions involving several nitrogen compounds and mammalian radioresistance].

Inhibition of monoamine oxidase (substrates tyramine or serotonin) with simultaneous appearance of diamine oxidase (substrates histamine or putrescine) and distinct increase in AMP-deaminating activities were found after total body X-ray irradiation (700 r) of white mice or rats in mitochondrial fractions isolated from their liver and intestines. These impairments in deamination of nitrogenous compounds in liver mitochondria of guinea pigs, which are must less radioresistant as compared with mice or rats, were noted after the irradiation at a dose 300 r, but in the liver mitochondria of mongolian gerbyls (Mariones unguiculatus), which are highly radioresistant, the irradiation even at a dose 1500 r did not cause appearance either of histamine or of AMP-deaminating activities while the decrease in the monoamine oxidase activity was not statistically significant. Feeding to the mice the grasses, which comprize the fodder of mongolian gerbyls under natural conditions, increased radioresistance of the animals and prevented at the same time appearance in the mitochondrial fractions of liver and intestines of those impairments in deamination of nitrogenous compounds which accompanied development of irradiation injuries.

Adenosine Monophosphate↗