PubMed Health⌕ Search

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.

At least 577 records · Page 32Linked to original sources
PubMed2001

Evaluation of microbial proteolysis in meat products by capillary electrophoresis.

AIMS: The available methods for evaluating proteolysis in meat products, particularly the contribution of micro-organisms, are expensive, time-consuming and require an unacceptable sample size. To minimize these problems, two capillary electrophoresis-based methods have been developed. METHODS AND RESULTS: Six Gram-positive, catalase-positive cocci, four moulds and three yeasts, isolated from dry-cured ham, were tested on sterile pork slices. Using the Capillary Gel Electrophoresis (CGE) method, changes in sarcoplasmic and myofibrillar proteins due to endogenous and microbial enzymes were detected. The Capillary Zone Electrophoresis (CZE) analysis allowed evaluation of bulk changes by micro-organisms in soluble nitrogen compounds. CONCLUSION: CGE analysis of myofibrillar proteins and CZE determination of soluble nitrogen compounds have proved to be valuable tools for evaluating proteolytic activity of endogenous and microbial origin. SIGNIFICANCE AND IMPACT OF THE STUDY: The CGE and CZE methods developed can be used for a rapid and sensitive analysis of proteolysis in meat products.

Animals↗
PubMed1991

[Nitrate and nitrite levels in daily food rations of children from the rural Puławy regions].

In the region of Puławy where the operation of the Nitrogen-Compound Manufacturing Plant has lead to an increase in nitrogen compound emission to the environment, nitrate and nitrite contents in daily food rations of children were determined. Daily food rations of children aged 8-9 and 12-13 years were collected from individual farms in four villages situated in the vicinity of the Nitrogen Plant, as well as--for control--from individual farms in Janowiec, a village distant from this Plant. Nitrate and nitrite contents were assayed in 300 daily food rations taken in spring and autumn. Nitrate was reduced to nitrite on a cadmium column whereupon it was determined colorimetrically using sulphanilic acid and N-1-napthyl-ethylenediamine. It was found that in the group of younger children as many as 70%, on the average, of the examined food rations displayed nitrate contents exceeding the admissible levels. In the group of the 12-13 years old children, the percentage of daily food rations whose nitrate content exceeded the admissible level was lower, averaging ca. 30% of all rations examined. The percentage of the daily food rations in which the nitrite content was higher than admissible level was closely similar in both groups of children, averaging ca. 30% of all rations examined. Food rations collected in spring, as compared with those taken in autumn, contained significantly greater amount of nitrate. In both periods of studies, nitrate contents were greater in the food rations from the farms situated near the Nitrogen Plant than in the food rations from farms in Janowiec.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2001

Genetics of larval urea and ammonia tolerance and cross-tolerance in Drosophila melanogaster.

Five laboratory populations of Drosophila melanogaster previously selected for over 60 generations for larval resistance to ammonium chloride (NH4Cl), and five populations selected for over 60 generations for larval resistance to urea, were investigated to determine the genetic mechanisms through which such tolerance had evolved. To examine the genetics of tolerance to urea and ammonia, egg-to-adult survivorship and developmental time were measured at two different NH4Cl levels and two different urea levels for each selection regime relative to the control lines, and among reciprocal crosses between each selection regime and the control lines. To examine tolerance to novel nitrogenous compounds (cross-tolerance), egg-to-adult survivorship and developmental time were measured at two different NH4Cl levels and two different urea levels for reciprocal crosses between the selection lines. Dominance is a major genetic factor in egg-to-adult survivorship in the presence of either urea or ammonia, while cross-tolerance to novel nitrogenous compounds also shows dominance as a major genetic mechanism controlling egg-to-adult survivorship. Dominance and X-linkage appear to be factors affecting developmental time in the presence of either urea or ammonia, although we could not exclude cytoplasmic inheritance as influencing our results. Cross-tolerance to novel nitrogenous compounds shows dominance and X-linkage as the main genetic factors controlling developmental time. We develop a simple hypothesis, in accordance with the results, that there may be two X-linked loci: one controlling urea tolerance and one controlling ammonia tolerance, and one autosomal locus exerting a pleiotropic control of tolerance. However, many other possibilities exist.

Ammonium Chloride↗
PubMedDate not supplied

Exposure to oxidized nitrogen: lipid peroxidation and neonatal health risk.

Pregnant women exposed to extensive environmental contamination by oxidized nitrogen compounds were studied at parturition, their neonatal health status was assessed and the involvement of oxidative stress in pathology was evaluated. Methemoglobin in maternal and cord blood was measured as a biomarker of individual exposure. Blood lipid peroxides and glutathione (reduced and total) were determined as oxidative stress biomarkers. Birthweight, Apgar scores, and clinical diagnosis at birth were used as neonatal health endpoints. Elevated exposure to oxidized nitrogen compounds was associated with increased lipid peroxidation in both maternal and cord blood. Poor birth outcome was associated with high blood lipid peroxides. Controlling for maternal age, parity, and smoking did not affect the relationships materially. The results showed that maternal/fetal exposure to oxidized nitrogen compounds is associated with increased risk of adverse birth outcome and suggest a role of oxidative damage in the pathogenic pathway.

Adolescent↗
PubMed2001

Development of an analytical method for the simultaneous determination of 15 carcinogenic polycyclic aromatic hydrocarbons and polycyclic aromatic nitrogen heterocyclic compounds. application to diesel particulates.

A new method enabling the determination of 15 priority carcinogenic polyaromatic compounds (PAC) proposed by the US National Toxicology Program (NTP) has been developed and applied to diesel exhaust particulates (DEP). The clean-up procedure consists of solid-phase extraction (SPE) and HPLC fractionation on silica phases followed by liquid-liquid extraction and chromatography on a polyvinylbenzene copolymer column. The method gives good recoveries for all PAC studied except dibenzo[a,j]acridine and dibenzo[a,h]pyrene, for which recovery values are below 80%. The use of GC-MS ion trap and its capacity to achieve single-ion storage enhanced the sensitivity of the method, enabling the detection of high-molecular-weight PAH in the low ng g(-1) concentration range. Intermediate polarity GC columns, e.g. BPX-50 or equivalent, enabled better separation, when applied to DEP analysis, than the generally used DB-5 apolar phase. This is observed mainly for separation of isomeric compounds belonging to the benzofluoranthene and dibenzopyrene families. The application of this method to DEP sampled from the exhaust of a diesel engine and in confined locations such as a tunnel has shown that all PAH of the NTP list could be detected, except dibenzo[a,h]pyrene. No dibenzacridine or dibenzocarbazole could be detected in such matrices. The method is sufficiently sensitive to be applicable to environmental exposure measurements in occupational health surveys.

Algorithms↗
PubMed1981

Mutagenicity of nitro derivatives induced by exposure of aromatic compounds to nitrogen dioxide.

Mutagenic nitro derivatives were readily induced when 6 kinds of chemicals were exposed to 10 ppm of nitrogen dioxide (NO2). Single nitro derivatives were formed from pyrene, phenanthrene, fluorene or chrysene. Carbazole and fluoranthene each produced 2 derivatives substituted with nitro groups at different positions. The formation of nitro derivatives was enhanced by exposure of pyrene to NO2 containing nitric acid (HNO3, less than 100-fold enhancement) or sulphur dioxide (SO2, less than 15-fold enhancement). After 24 h of exposure the yields of the nitro derivative were 0.02% with 1 ppm of NO2 in air and 2.85% with NO2 (1 ppm) containing traces of HNO3. The nitro derivatives from all but phenanthrene and carbazole were chemically identified by means of gas chromatography (GC) and mass spectrometry (MS), and the mutagenicity of the 4 kinds of authentic nitro derivatives was tested by using Salmonella strains TA98 and TA1538 with or without the S9 fraction from rat liver treated with Aroclor 1254. The nitro derivative induced from pyrene was determined to be 1-nitropyrene; that of chrysene was 6-nitrochrysene; that of fluorene was 2-nitrofluorene; and those of fluoranthene were 3-nitrofluoranthene, and 8-nitrofluoranthene. Tested with strain TA98 in the absence of the S9 fraction, the first 4 of these derivatives yielded, respectively, 3050, 269, 433 and 13 400 revertants per nmole. Thus, each nitro derivative formed was potentially a direct-acting frameshift-type mutagen. Each compound exposed to NO2 showed a decreased mutagenic activity when tested in the presence of S9 mix. A possible explanation comes from experiments in which 1-nitropyrene was incubated with the S9 mix at 37 degree C for 10 min, and 1-aminopyrene was formed. The mutagenic activity of 1-aminopyrene was appreciable, but only about one-tenth of that of 1-nitropyrene in the Ames test.

Heterocyclic Compounds↗
PubMed2006

[Cometabolic biodegradation of nitrogenous heterocyclic compounds indole and pyridine under anoxic conditions].

Based on the traditional theory of denitrification under anoxic conditions, and with the addition of nitrate, experiments were conducted to investigate the cometabolic biodegradation of nitrogenous heterocyclic compounds-indole and pyridine. Results show that the optimum ratio of COD to nitrate (C/N) is 8.4 to approximately 8.9. Under the conditions with temperature of 28 degrees C and pH of 7.0 to approximately 7.5, the nitrate reductase activity (NRA) is in the best state. Addition of pyridine can promote NRA and the degradation of indole. When the initial concentration of indole is 150 mg/L, the concentration ratio of indole to pyridine is 1 to approximately 10, and under the optimum C/N conditions, the degradation of indole meet with zero-order kinetics. There was no accumulation of nitrite during the reaction. When the concentration ratio of pyridine to indole is less than 0.25, with the increase of pyridine concentration, there is a faster augment rate for NRA and the degradation of indole than the situation when the concentration ratio of pyridine to indole is more than 0.25.

Biodegradation, Environmental↗
PubMed2005

Nitrogen-containing compounds from Salvia miltiorrhiza.

Five new N-containing compounds, neosalvianen (1), salvianen (2), salvianan (3), salviadione (4), and 5-(methoxymethyl)-1H-pyrrole-2-carbaldehyde (5), were isolated from Salvia miltiorrhiza. Their structures were mainly established by spectroscopic methods. Neosalvianen (1) and its analogues (6a, 6b) were synthesized for spectroscopic data comparison. Compounds 1, 2, 4, and 6a were evaluated for their cytotoxic activities against selected cancer cell lines. Among these components, salvianen (2) exhibited the most potent cytotoxicity with a CD50 range of 30.4-39.5 microM against HeLa (cervical epitheloid carcinoma), HepG2 (hepatocellular carcinoma), and OVCAR-3 (ovarian adenocarcinoma) cell lines in a dose-dependent manner. The cytotoxicities of the tested compounds were not specific and showed similar activities to the selected cancer cell lines.

Antineoplastic Agents, Phytogenic↗
PubMed1977

[Theophylline and theobromine derivatives of nitrogen heterocyclic compounds].

7-Theophylline derivatives with 4,6-dihydroxy-5-pyrimidinyl-, 3-oxopiperazinylmethyl- and 4-methyl-3,5-dioxopiperazinylmethyl substituents are described: they can be viewed as structural analogues of a nucleic base pair in the Hoogsteen arrangement; theobromine could be converted into the 1-(3,5-dioxo-4-pyrazolidinyl) derivative, similarly analogous to a base pair in the Watson-Crick arrangement.

Heterocyclic Compounds↗
PubMed1995

Development of a microbial community of bacterial and yeast antagonists to control wound-invading postharvest pathogens of fruits.

Two antagonists, the bacterium Pseudomonas syringae and the pink yeast Sporobolomyces roseus, against blue mold (caused by Penicillium expansum) on apple controlled this disease more effectively when combined at approximately equal biomass (50:50 of the same turbidity) than in individual applications. Addition of L-asparagine enhanced the biocontrol effectiveness of P. syringae but decreased that of S. roseus and had no significant effect when the antagonists were combined. Populations of both antagonists increased in apple wounds and were further stimulated by the addition of L-asparagine. The carrying capacity of wounds for P. syringae was not affected by S. roseus. Populations of P. syringae in wounds inoculated individually or in a 50:50 mixture with S. roseus reached the same level after 3 days at 22 degrees C. However, populations of S. roseus recovered after applications of the mixture were consistently lower than those recovered after individual applications. Similar effects were observed in in vitro tests in which populations of S. roseus grown in mixtures with P. syringae were consistently lower than those grown alone, while the populations of P. syringae were not affected by the presence of S. roseus. A total of 36 carbon and 35 nitrogen compounds were tested for utilization by both antagonists. Fourteen nitrogenous compounds were utilized by both P. syringae and S. roseus, and an additional nine compounds were utilized by P. syringae. S. roseus and P. syringae utilized 17 and 13 carbon sources, respectively; 9 sources were common to both antagonists. Populations of these antagonists in apple wounds appear to form a relatively stable community dominated by P. syringae.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomass↗
PubMed2002

[The influence of urea, ammonia and nitrate as they affect growth and viability of Trichophyton verrucosum].

Six strains of Trichophyton verrucosum were used in a test to determine effects of urea and sodium nitrate on their growth. Despite having urease activity, the strains failed to utilize the urea and sodium nitrate for their growth. Moreover, the organisms were killed if large amounts of these nitrogen compounds and ammonia were added to the medium. These nitrogen compounds, distributed in cattle breeding soil, inhibited the growth of T. verrucosum. Thus, soil in cattle breeding environments does not seem to be a reservoir of this pathogen.

Ammonia↗
PubMed2004

Chlorination byproduct formation in the presence of humic acid, model nitrogenous organic compounds, ammonia, and bromide.

The formation of trihalomethanes (THMs), haloacetic acids (HAAs), and cyanogen halides (CNXs) after chlorination of synthetic solutions containing humic acid, nitrogenous organic (N-organic) compounds, ammonia, and bromide ions was studied. Humic acid (from Aldrich) was used to provide the source of the precursors. Glycine was chosen as the primary model N-organic compound and other four model N-organic compounds (including glutamic acid, glycylglycine, diethylamine, and methylamine) were also evaluated for comparison. The formation of THMs and HAAs was found to decrease with increasing glycine and ammonia concentrations but to increase with increasing bromide ion concentration. CNX formation was found to be highly sensitive to free chlorine to glycine ratios, and its formation trends were significantly affected bythe presence/absence of ammonia. The incorporation of bromine changed the byproducts speciation toward brominated species and enhanced the yields of total THMs, HAAs, and CNXs. Different model N-organic compounds exerted different effects on the formation of THMs, HAAs, and CNXs. Their effects on the formation of THMs and HAAs were likely dependent on their reactivity to chlorine in competing with the humic acid chlorination reactions. The difference in the CNCI yields was attributable to the variations in the compound structures.

Ammonia↗