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At least 217 records · Page 12Linked to original sources
PubMed1992

Metabolism of nitrogenous compounds by ruminant liver.

Ruminants absorb substantial amounts of ammonia nitrogen and very little glucose. Ammonia absorbed is removed by the liver and converted to urea, which can be recycled to the digestive tract and add to the pool of ammonia absorbed. When ammonia absorption and liver urea production are increased by changes in nitrogen intake, an associated increase in liver alpha-amino nitrogen removal has been observed. Reasons for the increase in liver removal of amino acids with greater ureagenesis are uncertain, but the aspartate/glutamate requirement of ureagenesis and the complex relationships between ureagenesis and the tricarboxylic acid cycle, glucogenesis, liver energy metabolism and redox state all may be involved. Amino acids represent potential sources of carbon for liver glucogenesis and precise reckonings of the contributions of amino acid carbon to glucogenesis are needed for ruminants fed differing diets. There is evidence for the involvement of peptides in liver nitrogen exchanges and amino acids in peptides represent a potential source of carbon for glucogenesis and nitrogen for ureagenesis. A number of endocrine factors have an impact on liver nitrogen metabolism in ruminants. Growth hormone decreases liver urea release and increases liver glutamate release.

Amino Acids↗
PubMed1975

Comparative studies on the role of nitrogenous compounds in the growth and perithecial development of Chaetomium aureum.

Sodium nitrate is a suitable nitrogen source supporting growth and perithecial formation in Chaetomium aureum. 31 inorganic and organic nitrogen sources at a concentration of 0.033% were used at different incubating temperatures (25, 30 and 35 degrees C). The cultures were grown in Petri dishes, culture tubes and Erlenmeyer flasks. An incubating temperature of 30 degrees C was found most suitable for perithecial formation. In general, a nitrogen source in a solid medium could induce better perithecial production than in liquid media.

Amino Acids↗
PubMed2004

Changes in some nitrogenous compounds in the blood and tissues of freshwater pikeperch (Sander lucioperca) during salinity acclimation.

The effect of ambient salinity changes (0.9, 6 and 12 psu) on the levels of dissolved ammonia (DA), ninhydrin positive substances (NPS), trimethylamine (TMA) and trimethylamine oxide (TMAO) in the blood and tissue of medium-acclimated Sander lucioperca L. (also Stizostedion lucioperca) were investigated. In freshwater, blood and tissue total free amino acid levels (measured as NPS) were 3.62 mM and 60.61 mM, respectively. The NPS content increased significantly (P<0.05) in the tissue and blood on acclimation to 6 and 12 psu salinities. The mass-specific tissue TMAO concentration of pikeperch acclimated to normal freshwater was 0.413+/-0.084 micromol TMAO g(-1). Results reveal that TMAO levels are positively influenced by the external salinity medium where significant differences in mean levels occurred between the groups (P<0.05). The calculated p[NH(3)] and [NH(4)(+)] gradients reveal that the [NH(3)] gradient was consistently low (cf. the [NH(4)(+)] gradient). The gradient of p[NH(3)] decreased with the medium increased salinities. The results suggest that freshwater pikeperch may be able to resist salinity changes by manipulation of nitrogen metabolism. Free amino acids and TMAO are involved in mediating response to salinity exposure in freshwater pikeperch.

Adaptation, Physiological↗
PubMedDate not supplied

[The role of low-molecular-weight nitrogen compounds in the osmotolerance of Rhodococcus erythropolis and Arthrobacter globiformis].

Investigations showed that Rhodococcus erythropolis E-15 and Arthrobacter globiformis 2F cells respond to osmotic shock by increasing the synthesis of free amino acids, primarily glutamic acid (80% of the intracellular free amino acid pool). The osmoprotective role of glutamic acid follows from its beneficial effect on the growth of bacteria in high-salinity media. It was found that the addition of this amino acid to the growth medium at a concentration of 2 mM shortened the lag phase and increased the growth rate and biomass yield of either of the two bacteria. The addition of another osmoprotectant, trehalose, to the high-salinity growth medium of R. erythropolis E-15 at the same concentration (2 mM), restored the growth parameters of this bacterium to the control values.

Amino Acids↗
PubMed1994

Short-term space flight on nitrogenous compounds, lipoproteins, and serum proteins.

Biochemical variables in blood were measured in venous blood samples from 38 to 72 Space Shuttle astronauts before and immediately after flights of 2 to 11 days. Mean pre- and postflight values were compared using the paired t-test or the Wilcoxon signed-rank test. The largest change in serum enzymes was a 21% increase (P = .0014) in gamma-glutamyl-transpeptidase, which may have been related to stress. The median value of apolipoprotein (apo) A-I decreased from 152 to 127 mg/dL (P < .0001), but the change in apo B (77 to 73 mg/dL) was not statistically significant, and the mean apo A-I/apo B ratio remained well above 1.5. A decrease in dietary fat and cholesterol intake during shuttle missions may have been a cause of the change in apo A-I. Twelve of the 16 nonenzyme serum proteins measured were significantly elevated (P < .05), possibly because of hemoconcentration and increased protein catabolism. The 56% increase in haptoglobin may be related to release of suppressed erythropoiesis at landing.

Adult↗
PubMed1982

Electrochemical properties of polycyclic compounds studied by the polarographic method in anhydrous systems. VIII. The influence of proton-donor on reduction of carcinogenic nitrogen compounds in dimethylformamide.

The authors have studied the electrochemical behavior of a series of carcinogenic and inactive heterocyclic compounds in anhydrous medium in the presence of a proton-donor. As anhydrous medium the authors used anhydrous dimethylformamide as proton-donor phenol. In the presence of proton-donor there had occurred on polarographic reduction of the employed carcinogenic heterocyclic compounds changes in the number of polarographic waves. Between the two original waves in these compounds there arose in the presence of phenol a new wave. In non-carcinogenic heterocyclic compounds such an effect of phenol was not noted. In the present paper the authors discuss the possible mechanism of electroreduction of carcinogenic and inactive heterocyclic compounds in anhydrous medium in the presence of a proton-donor.

Aza Compounds↗
PubMed1992

Charge calculations in molecular mechanics. IX. A general parameterisation of the scheme for saturated halogen, oxygen and nitrogen compounds.

The CHARGE2 program for the calculation of partial atomic charges has been amended to include bond parameters for a number of organic functional groups, including halogens, nitrogen and oxygen. These minor amendments to the original scheme produce dipole moments for the fluoro and chloro compounds which are in complete agreement with the observed values. The less complete data sets for the bromo and iodo compounds are also well reproduced, and the dipole moments of a variety of mixed halo compounds are now in better agreement with experiment than previously. The calculated dipole moments of the saturated nitrogen and oxygen compounds are now in much better agreement than in the original scheme, thus the revised parameterisation may be employed with confidence to predict the electrostatic energies of these compounds. Furthermore, the revised scheme now gives a precise proportionality between the charge on the proton in a CH group and the 1H chemical shift of the corresponding proton, allowing the general prediction, in principle, of 1H chemical shifts. In addition, attempts to include variable electronegativity in the alpha effect are described for fluoro compounds.

Chemistry, Organic↗
PubMedDate not supplied

Cattle feedlot soil moisture and manure content: I. Impacts on greenhouse gases, odor compounds, nitrogen losses, and dust.

Beef cattle feedlots face serious environmental challenges associated with manure management, including greenhouse gas, odor, NH3, and dust emissions. Conditions affecting emissions are poorly characterized, but likely relate to the variability of feedlot surface moisture and manure contents, which affect microbial processes. Odor compounds, greenhouse gases, nitrogen losses, and dust potential were monitored at six moisture contents (0.11, 0.25, 0.43, 0.67, 1.00, and 1.50 g H2O g(-1) dry matter [DM]) in three artificial feedlot soil mixtures containing 50, 250, and 750 g manure kg(-1) total (manure + soil) DM over a two-week period. Moisture addition produced three microbial metabolisms: inactive, aerobic, and fermentative at low, moderate, and high moisture, respectively. Manure content acted to modulate the effect of moisture and enhanced some microbial processes. Greenhouse gas (CO2, N2O, and CH4) emissions were dynamic at moderate to high moisture. Malodorous volatile fatty acid (VFA) compounds did not accumulate in any treatments, but their persistence and volatility varied depending on pH and aerobic metabolism. Starch was the dominant substrate fueling both aerobic and fermentative metabolism. Nitrogen losses were observed in all metabolically active treatments; however, there was evidence for limited microbial nitrogen uptake. Finally, potential dust production was observed below defined moisture thresholds, which were related to manure content of the soil. Managing feedlot surface moisture within a narrow moisture range (0.2-0.4 g H2O g(-1) DM) and minimizing the accumulation of manure produced the optimum conditions that minimized the environmental impact from cattle feedlot production.

Animal Husbandry↗
PubMed2002

Flow injection determination of readily assimilable nitrogen compounds during vinification.

A flow injection method for the determination of readily assimilable nitrogen (r.a.n.), i.e. ammonium and aminated nitrogen, is reported. The difference in pH of the sample in the presence and absence of formaldehyde, which blocks the amino function, provides the value of r.a.n. by monitoring the changes in absorbance of bromothymol blue at 616 nm. The detection and quantification limits are 10 and 11.6 mg l(-1), respectively, the reproducibility and repeatability are 3.94 and 1.35 mg l(-1), respectively, and the sample throughput is 20 samples h(-1). The method has been applied to the analysis of 120 samples of must and wine subjected to biological aging. The proposed method also provides good correlation with the reference method used in routine analysis, and is faster

Journal Article↗
PubMed1984

Phosphorus-nitrogen compounds. 24. Phosphoramide mustard carrier derivatives.

Diethylstilbestrol, psoralen, and propranolol were used as potential carrier molecules for selective concentrations of a nitrogen mustard moiety in breast, skin, and lung tissues, respectively. The propranolol derivative gave two racemic mixtures, which were tested to ascertain any differences in anticancer activity. The insertion of a P = O group between the carrier and oncolytic portions offsets the excess lipophilic contribution of the latter and possibly provides for latentiation of alkylating activity. Murine tumor testing of the phosphoramide mustard derivatives and two intermediates indicated that two compounds possessed marginal activity against mammary carcinoma and lymphocytic leukemia.

Animals↗
PubMed2001

Carbohydrate and nitrogenated compounds in liquid smoke flavorings.

Commercial smoke flavorings were extracted with dichloromethane and the remaining aqueous phase was evaporated at room temperature; the residues obtained were dissolved in methanol and studied by gas chromatography/mass spectrometry. The composition of these residues was totally different from that of the dichloromethane extracts, constituting a small number of compounds that were also detected in the dichloromethane extract, as well as a large number of compounds not described before as components of either smoke for food smoking or smoke flavorings. Among those compounds not previously described there are some furan, pyran, and phenolic derivatives, as well as some pyridine and carbohydrate derivatives. The main component of these fractions is 1,6-anhydro-beta-D-glucopyranose, or levoglucosan. Likewise, aqueous residues of liquid smoke flavorings, prepared at a laboratory scale from beech, vine shoots, thyme, and sage, were studied in the same way. These contained compounds of the same groups cited above, but showed clear differences. The aqueous residue of beech smoke flavoring was the most similar to that of the commercial smoke flavorings. The aqueous residues of vine shoots, thyme, and sage smoke flavorings contained a lower number of furan, pyran, and carbohydrate derivatives and a higher number of nitrogenated derivatives. Instead of levoglucosan, the main component was an unidentified compound, present in all samples, included in the carbohydrate derivatives group. In the samples studied, the influence of the vegetal source on the composition of the aqueous fraction has been shown. In the future, attention must be paid to the functionality of these smoke components.

Carbohydrates↗
PubMed1984

Net absorption of glucose and nitrogenous compounds by lactating Holstein cows.

Net absorptions from portal-drained viscera of glucose, ammonia nitrogen, alpha-amino nitrogen, and urea nitrogen were measured in four Holstein cows in first lactations. Cows were fed for ad libitum consumption a completely mixed, 60:40 corn silage:supplement diet (dry basis) in two equal feedings at 12-h intervals daily. Portal blood flow (dye dilution) and net absorption (portal-arterial difference times portal blood flow) were measured at hourly intervals for 12 h for all cows 4 and 8 wk postpartum and for two cows 4, 8, 12, 16, and 20 wk postpartum. Apparent digestibilities of dry matter and nitrogen were measured immediately after net absorption. Milk yield and composition were measured with absorption and digestion. Mean daily dry matter intake and milk yield were 14.1 +/- .6 and 23.8 +/- 1.8 kg. Portal blood flow was not affected by time of day or weeks postpartum; mean was 1371 +/- 123 liters/h. Net absorption of glucose was negative, indicating no uptake of glucose from dietary sources. Means (g/day) for nitrogenous sources were: nitrogen intake 387, fecal nitrogen 121, urinary nitrogen 146, milk nitrogen 116, net ammonia nitrogen absorption 149, net alpha-amino nitrogen absorption 137, and net loss of urea nitrogen from blood to the gut 93. Net absorption of amino nitrogen and alpha-amino nitrogen in blood was greater than in plasma; corresponding losses of urea nitrogen and glucose to the gut were greater from blood than plasma.

Amines↗