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PubMed2005

Application of the ADM1 model to advanced anaerobic digestion.

In this paper the ADM1 model that has been developed by the IWA Task Group for Mathematical Modelling of Anaerobic Digestion Processes is summarized. The model was applied to a variety of anaerobic digestion scenarios that are presented in the literature and for each data set the model predictions were compared to experimental values. Based upon the model applications it was apparent that for accurate model simulations the influent sludge should be well characterized in terms of biodegradable and recalcitrant COD and also nitrogenous compounds. In almost all cases the model was able to reflect the trends that were observed in the experimental data however the concentrations of VFAs were consistently over-predicted in digesters with short SRTs. It would appear that the inhibition functions associated with low pH values tend to overestimate the impact of pH on biokinetic rates for the acid-consuming bacteria. Application of the model with flow through of active biomass between digesters in series in temperature-phased systems needs to be further evaluated in the future.

Bacteria, Anaerobic↗
PubMed2004

Biochemical dynamics of spermatogenesis and oogenesis in Eledone cirrhosa and Eledone moschata (Cephalopoda: Octopoda).

The effect of spermatogenesis and oogenesis on protein, lipid, glycogen, cholesterol and energy contents, total amino acid and fatty acid profiles of Eledone cirrhosa and Eledone moschata tissues (gonad, digestive gland and muscle) was investigated. A significant (p<0.05) increase in the amino acids and protein content of the gonad throughout sexual maturation (namely in oogenesis) was observed, but the allocation of these nitrogen compounds from the digestive gland and muscle was not evident. The major essential amino acids (EAA) in the three tissues were leucine, lysine and arginine. The major nonessential amino acids (NEAA) were glutamic acid, aspartic acid and alanine. A significant increase in lipid and fatty acid contents of gonad and digestive gland was observed. There was also little evidence of accumulated lipid storage reserves being used for egg production. It seems that for egg production Eledone species use energy directly from food, rather than from stored products. Most of saturated fatty acid (SFA) content of the three tissues was presented as 16:0 and 18:0, monounsaturated fatty acid (MUFA) content as 18:1 and 20:1 and polyunsaturated fatty acid (PUFA) content as 20:4n-6, 20:5n-3 and 22:6n-3. Cholesterol and glycogen contents significantly increased in gonad and digestive gland throughout maturation while the muscle revealed no obvious pattern. If Eledone's component sterols are of a dietary origin, a considerable variation in the cholesterol content between species might be expected on the basis of the sterol composition of their prey. Although spermatogenesis and oogenesis had a significant effect (p<0.05) in gonad and digestive gland energy content, the biochemical composition of digestive gland and muscle may not be primarily influenced by sexual maturation, but rather by other biotic factors such as feeding activity, food availability, spawning and brooding.

Animals↗
PubMed2006

Nitrite in nitric oxide biology: cause or consequence? A systems-based review.

All life requires nitrogen compounds. Nitrite is such a compound that is naturally occurring in nature and biology. Over the years, the pharmacological stance on nitrite has undergone a surprising metamorphosis, from a vilified substance that generates carcinogenic nitrosamines in the stomach to a life-saving drug that liberates a protective agent (nitric oxide or NO) during hypoxic events. Nitrite has been investigated as a vasodilator in mammals for over 125 years and is a known by-product of organic nitrate metabolism. There has been a recent rediscovery of some of the vasodilator actions of nitrite in physiology along with novel discoveries which render nitrite a fundamental molecule in biology. Until recently nitrite was thought to be an inert oxidative breakdown product of endogenous NO synthesis but the past few years have focused on the reduction of nitrite back to NO in the circulation as a possible mechanism for hypoxic vasodilatation. Nitrite has evolved into an endogenous signaling molecule and regulator of gene expression that may not only serve as a diagnostic marker but also find its role as a potential therapeutic agent of cardiovascular disease. These data therefore warrant a reevaluation on the fate and metabolism of nitrite in biological systems. This review serves to encompass the history and recent evolution of nitrite, the compartment-specific metabolism of nitrite and its role in plasma as a biomarker for disease, the role of nitrite as a potential regulator of NO homeostasis, and the future of nitrite-based research.

Animals↗
PubMed2006

Fermentation behaviour and metabolic interactions of multistarter wine yeast fermentations.

Multistarter fermentations of Hanseniaspora uvarum, Torulaspora delbrueckii and Kluyveromyces thermotolerans together with Saccharomyces cerevisiae were studied. In grape musts with a high sugar content, mixed trials showed a fermentation behaviour and analytical profiles of wines comparable to or better than those exhibited by a pure culture of S. cerevisiae. Sequential trials of T. delbrueckii and K. thermotolerans revealed a sluggish fermentation, while those of H. uvarum exhibited an unacceptable increase in ethyl acetate content (175 ml l(-1)). A low fermentation temperature (15 degrees C) of multistarter trials of H. uvarum resulted in a stuck fermentation that was not due to a deficiency of assimilable nitrogenous compounds since lower amounts of these compounds were used. Sequential fermentation carried out by H. uvarum at 15 degrees C confirmed the high production of ethyl acetate. The persistence and level of non-Saccharomyces yeasts during multistarter fermentations under stress conditions (high ethanol content and/or low temperature) can cause stuck fermentations.

Acetates↗
PubMed2006

IPEADAM study: indoor endotoxin exposure, family status, and some housing characteristics in English children.

BACKGROUND: Many environmental factors have been investigated to determine their involvement in the asthma epidemic. OBJECTIVE: We sought to investigate the indoor environment of English children. METHOD: The Indoor Pollutants, Endotoxin, Allergens, Damp and Asthma in Manchester (IPEADAM) study recruited 200 asthmatic and age-, sex-, and sibship size-matched nonasthmatic children after a questionnaire-based community screening epidemiology survey. Their homes were sampled for several indoor air factors, and reservoir dust samples were obtained. Endotoxin, Der p 1, and dampness levels were assayed. Questionnaires were administered to record housing characteristics. Indoor pollutants, including environmental tobacco smoke, volatile organic compounds, nitrogen dioxide, formaldehyde, temperature, and relative humidity, were investigated. STATA univariate and multivariate analyses were used to compare the indoor environments of the children. RESULTS: The levels of endotoxin (adjusted odds ratio, 1.88; 95% CI, 1.11-3.18; P=.018), living in a single-parent family (adjusted odds ratio, 3.89; 95% CI, 1.25-12.1; P=.019), redecoration in the living room (adjusted odds ratio, 3.15; 95% CI, 1.36-7.33; P=.008), and self-reported absence of dampness (adjusted odds ratio, 0.36; 95% CI, 0.14-0.91; P=.030) were all independent predictive factors of asthma. There was no difference between asthmatic and healthy children in their exposure to Der p 1, objective measurements of dampness, guardian's smoking habits, pet ownership, house type or age, time in residence, central heating systems, insulation types, glazing systems, floor types, and age and measurements of several indoor pollutants. CONCLUSION: The IPEADAM study has shown that there were very few differences in the indoor environments of English asthmatic and nonasthmatic children. However, once asthma has been established, the presence of endotoxin is positively associated with an asthmatic child's living room carpet reservoir dust. CLINICAL IMPLICATIONS: There are no direct clinical implications of this research, although it needs interpreting with other clinical data on endotoxin exposure in epidemiologic settings.

Adolescent↗
PubMed2006

Effects of mechanical stress on Anammox granules in a sequencing batch reactor (SBR).

The effect of shear stress on Anammox process was studied in a sequencing batch reactor (SBR). The reactor was operated during 218 days under different stirring speeds (60-250 rpm) in order to expose the system to different shear conditions and to study the stability of the Anammox granules referred to their biological activity and size. The nitrogen loading rate (NLR) fed to the SBR was kept around 0.3g N(L day)(-1). The nitrite (limiting substrate) removal percentage was 98% during most of the operational period. The specific Anammox activity of the biomass was practically constant and around 0.4 g N(g VSSday)(-1) and the average feret diameter of the formed granules was 0.64 mm. Obtained results indicated that stirring speeds up to 180 rpm have no negative effect on the performance of the Anammox process, whereas Anammox activity decreased to 40% when a rotating speed of 250 rpm was tested and the average diameter decreased in 45%, the concentration of solids in the effluent increased to 0.2g TSSL(-1) and nitrite was accumulated in the reactor up to 60 mg NL(-1).

Anaerobiosis↗
PubMed2005

Investigation of pyrolysis behavior of carbofuran by pyrolysis-gas chromatography-mass spectrometry.

Carbofuran is a kind of carbamate pesticide commonly used on major crops. For understanding of the composition variation versus temperature and pyrolysis mechanism, its pyrolysis behavior was simulated and investigated by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). The pyrolysates were directly injected for GC-MS analysis. Totally 86 components were determined based on mass spectra library matching with the aid of the correlation of boiling point (bp) and retention time. It was found that carbofuran was obviously decomposed with the temperature increase. A large number of mono aromatics and polycyclic aromatic hydrocarbons (PAHs) were formed when the temperature was higher than 750 degrees C, and the higher was the temperature, the more was the content of the corresponding aromatic hydrocarbon. Besides the aromatic hydrocarbons, there were oxygenous and/or nitrogenous compounds produced in the pyrolysis process. Furthermore, the pyrolysis mechanism of carbofuran was proposed based on the determined pyrolysates and their contents variation versus the temperature. The investigation results can provide the useful information for understanding of the thermal behavior of carbofuran and evaluation of the potential influence of the pyrolysates to living thing and the environment.

Carbofuran↗
PubMed2005

Separation and determination of pseudoephedrine, dextromethorphan, diphenhydramine and chlorpheniramine in cold medicines by nonaqueous capillary electrophoresis.

An easy, rapid and simple nonaqueous capillary electrophoresis (NACE) method was developed for the identification and determination of four basic nitrogenous compounds, i.e. pseudoephedrine (PE), dextromethorphan (DXM), diphenhydramine (DHM) and chlorpheniramine (CLP). The most suitable running buffer was composed of 40 mM ammonium acetate, 10% acetonitrile (ACN) in methanol with a fused-silica capillary column (47 cm x 75 microm i.d.), 25 kV applied voltage and 25 degrees C capillary temperature. The calibration curves revealed linear relationships between the peak area for each analyte and its concentration (correlation coefficients: 0.9993 for PE, 0.9971 for DXM, 0.9991 for DHM, and 0.9995 for CLP, respectively). The relative standard deviations of the migration time and peak area of the four compounds were 0.37, 3.90, 0.73 and 0.68, and 2.80, 3.50, 1.60 and 3.70%, respectively. The method was successfully applied to determine the four compounds in five cold medicines, the recoveries of the four constituents ranging between 91 and 109%.

Chlorpheniramine↗
PubMed2004

Oxidative stress and inhibition of oxidative phosphorylation induced by peroxynitrite and nitrite in rat brain subcellular fractions.

Nitrite and nitrate, two endogenous oxides of nitrogen, are toxic in vivo. Furthermore, the reaction of superoxide (produced by all aerobic cells) with nitric oxide (NO) generates peroxynitrite, a potent oxidizing agent, that can cause biological oxidative stress. Using subcellular fractions from rat brain hemispheres we studied oxidative stress induced by these nitrogen compounds with special emphasis on nitrite. The consumption of Vitamin C (ascorbate) and Vitamin E (alpha tocopherol), two of the important nutritional antioxidants, was followed in synaptosomes (nerve-ending particles) and mitochondria along with changes in parameters of mitochondrial oxidative phosphorylation. Nitrite, but not nitrate, oxidized ascorbate without oxidizing alpha tocopherol in both synaptosomes and mitochondria whereas peroxynitrite oxidized both ascorbate and alpha tocopherol. Functionally, both nitrite and peroxynitrite inhibited mitochondrial oxidative phosphorylation. Nitrite was less potent than peroxynitrite when the effects of equal concentrations of the two were compared. However, since nitrite is much more stable than peroxynitrite the impact of nitrite as an oxidant in vivo could be as much or even more significant than peroxynitrite. Nitrate would not have similar action unless it is reduced to nitrite. It is possible that nitrite may impair oxidative phosphorylation through modulating levels of nitric oxide, changing the activity of heme proteins or a mild uncoupling of mitochondria.

Animals↗
PubMed2006

Lung toxicity of nitrogen mustard may be mediated by nitric oxide and peroxynitrite in rats.

Nitric oxide (NO) has previously been shown to be responsible for nitrogen mustard (NM)-induced tissue toxicity. Excessive amounts of NO are known to be able to produce peroxynitrite, an important reactive nitrogen compound, by reacting with superoxide. Previous studies reported that NO synthase inhibitors are able to prevent NM toxicity. The aim of this study was to evaluate whether peroxynitrite is also responsible for NM-induced lung tissue damage in rats. Wistar rats were divided into four groups. NM was injected intratracheally and was treated with the selective inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine (AG) (intraperitoneal) or the peroxynitrite scavenger ebselen (intragastric). Control animals were exposed to saline only. NM injection caused both oxidative and nitrosative stress, reflected by dramatically increased levels of the lipid peroxidation end product malondialdehyde (MDA), iNOS activation and urine nitrite-nitrate (NOx) values. Histopathological evaluation demonstrated lung damage with NM exposure. AG blocked iNOS activation and decreased urine NOx levels, and resulted in less histopathological changes in the lung. Although the histopathological outcome was found to be similar to AG, ebselen did not change urinary NOx or lung iNOS levels. Furthermore, ebselen was more able than AG to protect against MDA accumulation. In conclusion, the ability of ebselen to prevent against lung damage without blocking NO synthesis suggests that peroxynitrites may have an important role in the pathogenesis of NM toxicity in addition to NO.

Alkylating Agents↗
PubMed2005

Nitrobacter and Nitrospira genera as representatives of nitrite-oxidizing bacteria: detection, quantification and growth along the lower Seine River (France).

Pollution from agriculture and urban effluents influences the ecology and biochemical functioning of the Seine River. Nitrification dominates nitrogen transformations downstream of the effluents of the Paris wastewater treatment plant (WWTP) at Achères, treating, by activated sludge the wastewater of 6.5 million inhabitant equivalents from Paris and its suburbs, without nitrification and denitrification treatment. It discharges effluents containing large amounts of nitrogen, ammonium mostly (approximately 30 mg L(-1) N-NH(4+) L(-1)), on average 45 mg L(-1) of suspended particulate matter, high quantities of total organic carbon (approximately 30 mg C L(-1)) largely biodegradable (40%), and high concentration in total phosphorus ( approximately 3 mg Tot P L(-1)), as well as microorganisms. Ammonium, brought into the river system, is slowly nitrified in the lower Seine River and especially in the freshwater estuary. The nitrifying activities can be observed by measuring inorganic nitrogen compound concentrations and potential activities. To understand the contributions of the WWTP effluents, the upstream agricultural runoff water and the Seine tributaries, it is useful to investigate the bacterial community. Whereas ammonia oxidation has been widely studied, the second step, i.e. nitrite oxidation, is less well understood. We have previously analysed the ammonium-oxidizing bacterial (AOB) community in the Seine (Cébron, A., Berthe, T., Garnier, J., 2003. Nitrification and nitrifying bacteria in the lower Seine River and estuary (France). Appl. Environ. Microbiol. 69, 7091-7100; Cébron, A., Coci, M., Garnier, J., Laanbroek, H.J., 2004. DGGE analysis of the ammonia oxidizing bacterial community structure in the lower Seine River: impact of the Paris wastewater effluents. Appl. Environ. Microbiol. 70, 6726-6737), and focus here on the composition of the nitrite-oxidizing bacterial (NOB) community. As no general molecular probe targeting all known NOBs is currently available, we chose to target and quantify (by competitive PCR) the two genera Nitrobacter and Nitrospira assumed to be the major players in nitrite oxidation in freshwater environments. Nitrobacter species were dominant in the upstream Seine River basin but Nitrospira was the dominant NOB downstream of the WWTP. These two genera were equally represented in WWTP effluents. In the Seine River estuary, especially in the salinity gradient, the Nitrobacter proportion increases and that of Nitrospira disappears, possibly due dilution by seawater.

Bacteria↗
PubMed2000

Direct observation of trapping and release of nitric oxide by glutathione and cysteine with electron paramagnetic resonance spectroscopy.

While the biosynthesis of nitric oxide (NO) is well established, one of the key issues that remains to be solved is whether NO participates in the biological responses right after generation through biosynthesis or there is a "secret passage" via which NO itself is trapped, transported, and released to exert its functions. It has been shown that NO reacts with thiol-containing biomolecules (RSH), like cysteine (Cys), glutathione (GSH), etc., to form S-nitrosothiols (RSNOs), which then release nitrogen compounds, including NO. The direct observation of trapping of NO and its release by RSNO has not been well documented, as most of the detection techniques measure the content of NO as well as nitrite and nitrate. Here we use spin-trapping electron paramagnetic resonance (EPR) technique to measure NO content directly in the reaction time course of samples of GSH and Cys ( approximately mM) mixed with NO ( approximately microM) in the presence of metal ion chelator, which pertains to physiological conditions. We demonstrate that NO is readily trapped by these thiols in less than 10 min and approximately 70-90% is released afterward. These data imply that approximately 10-30% of the reaction product of NO does not exist in the free radical form. The NO release versus time curves are slightly pH dependent in the presence of metal ion chelator. Because GSH and Cys exist in high molar concentrations in blood and in mammalian cells, the trapping and release passage of NO by these thiols may provide a mechanism for temporal and spatial sequestration of NO to overcome its concentration gradient-dependent diffusion, so as to exert its multiple biological effects by reacting with various targets through regeneration.

Copper↗
PubMed1983

Analysis of some commercial preparations for migraine treatment using ion-pair high-performance liquid chromatography with addition of salts to the mobile phase.

When appropriate salts are added to the mobile phase in ion-pair high-performance liquid chromatography (HPLC) it is possible to arrive at an isocratic solvent with which complex mixtures of nitrogenous compounds of different pKa values and lipophilic characteristics may be separated. Selectivity in the manipulation of solute retention depends on the salt type, its concentration, the percentage of organic modifier in the mobile solvent and the solute itself. In addition to a dramatic reduction in analysis time, the use of salts can also improve the resolution of closely eluted peaks. With judicious control of the pH of the mobile solvent, the addition of salts to the mobile phase can cause the retention of compounds of different pKa values to alter in a contrasting manner. Under typical ion-pair HPLC conditions, an increase in salt concentration in the mobile solvent enhances the retention of neutral compounds and reduces the retention of ionized compounds. An inverse log-log relationship between the capacity factor of a solute and the salt concentration in the mobile phase was found. Examples are given of the use of salts in mobile solvents for ion-pair HPLC of a number of pharmaceutical preparations employed for the treatment of migraine.

Analgesics↗
PubMed2001

Simultaneous organic and nitrogen removal from municipal landfill leachate using an anaerobic-aerobic system.

An anaerobic-aerobic system including simultaneous methanogenesis and denitrification was introduced to treat organic and nitrogen compounds in immature leachate from a landfill site. Denitrification and methanogenesis were successfully carried out in the anaerobic reactor while the organic removal and nitrification of NH4+,-N were carried out in the aerobic reactor when rich organic substrate was supplied with appropriate hydraulic retention time. The maximum organic removal rate was 15.2 kg COD/m3 d in the anaerobic reactor while the maximum NH4+-N removal rate and maximum nitrification rate were 0.84kg NH4+-N/m3/d and 0.50kg NO3--N/m3/d, respectively, in the aerobic reactor. The pH range for proper nitrification was 6-8.8 in the aerobic reactor. The organic compounds inhibited nitrification so that the organic removal in the anaerobic reactor could enhance the nitrification rate in the following aerobic reactor. The gas production rate was 0.33 m3/kg COD and the biogas compositions of CH4, CO2, and N2 were kept relatively constant, 66-75, 22-32, and 2-3%, respectively.

Aerobiosis↗
PubMed2000

Characterisation of riverine particulate organic matter by pyrolysis-gas chromatography-mass spectrometry.

Particulate matter samples were collected in the mountainous section and river mouth at the Tech River basin, south France, during flood (December 1996) and summer (September 1997) periods. Suspended material was analysed by pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and 23 identified pyrolysis products were divided into five main fractions: aminosugars, aromatic hydrocarbons, polysaccharides, phenols and nitrogenous compounds. Analysis of relative amounts of these fractions revealed neither significant spatial nor temporal changes in the particulate organic matter composition. Nevertheless, their specific composition showed that during flooding there is a certain homogeneity in the composition of the riverine particulate organic matter, with more degraded material of pedogenic (allochthonous) character, and during the summer the results suggest the presence of two components, allochthonous and autochthonous.

Disasters↗
PubMed2003

The catalytic effect of Mg2+ and imidazole on the decomposition of 5-phosphoribosyl-alpha-1-pyrophosphate in aqueous solution.

The rate of decomposition of aqueous solutions of 5-phosphoribosyl-alpha-1-pyrophosphate (PRPP) is greatly enhanced by the presence of certain divalent ions. High levels of Mg(2+) were shown to increase the rate of phosphate removal from PRPP by factors greater than 100-fold. The combined action of Mg(2+) and a nitrogenous compound (imidazole was employed in this study) increases the degradation rate constants by up to 1000-fold. The degradation of PRPP in neutral solutions follows two main paths, a pyrophosphate hydrolysis reaction yielding ribose 5-phosphate and an internal beta-phosphate cleavage yielding 5-phosphoribosyl-1,2 cyclic phosphate. The catalytic effect of Mg(2+) on PRPP degradation appears to suggest a connection between the observed rate enhancements and the dimagnesium form of PRPP. Rate enhancing effects of Mg(2+) are greatest at pH values (i.e. pH>7) which promote strong phosphate-Mg(2+) interaction.

Catalysis↗
PubMed1996

Study of the amidase signature group.

Computer methods for database search, multiple alignment and cluster analysis indicated significant homology between amino-acid sequences of 21 amidases or amidohydrolases (EC 3.5). All of them were found to be involved in the reduction of organic nitrogen compounds and ammonia production. A conserved motif was found which may be important in amide binding and in catalytic mechanisms. Homology studies between these amidases and some ureases, nitrilases and acyl-transferases or enzymes with unknown functions provided new insight into the evolution of these proteins. Dissemination of these genes seemed to be facilitated by transfer of genetic elements such as transposons and plasmids.

Amidohydrolases↗
PubMed2001

Effect of freeze drying and protectants on viability of the biocontrol yeast Candida sake.

The effects of freezing method, freeze drying process, and the use of protective agents on the viability of the biocontrol yeast Candida sake were studied. Freezing at -20 degrees C was the best method to preserve the viability of C. sake cells after freeze drying using 10% skim milk as a protectant (28.9% survival). Liquid nitrogen freezing caused the highest level of damage to the cells with viability < 10%. Different concentrations of exogenous substances including sugars, polyols, polymers and nitrogen compounds were tested either alone or in combination with skim milk. There was little or no effect when additives were used at 1% concentration. Galactose, raffinose and sodium glutamate at 10% were the best protective agents tested alone but the viability of freeze-dried C. sake cells was always < 20%. Survival of yeast cells was increased from 0.2% to 30-40% by using appropriate protective media containing combinations of skim milk and other protectants such as 5% or 10% lactose or glucose, and 10% fructose or sucrose.

Animals↗