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PubMedDate not supplied

Thymo-adrenals reaction in pre-pubertal and pubertal Wistar rats in response to acute administration of calcitonin.

Pre- and post-pubertal Wistar rats were injected i.m. with a single dose equivalent to 1 UI of Calcitonin (Calsyn-50 Rorer, Swiss). Its effects upon the thymus and adrenals were assessed after 1, 3 and respectively, 8 days since injection. The results pointed to differences of reaction of the thymus and adrenals dependent on rat ages and on the period of hormone persistence in the organism. The effects in mature rats are characterized by a stress state, reflected in adrenal reaction, but without impact upon the thymus in point of biochemical parameters. In rats of that age, modifications in both organs are much reduced after 8 days since calcitonin injection. In pubertal rats, adrenal activity is temperate, and thymus registers modification of DNA, of oxygen consumption and of nitrogen aminic after 3 days since injection. This modification is maintained for 8 days.

Adrenal Glands↗
PubMed1982

[Use of proteins in the feed mixture in early weaning of pigs].

Eighty-three piglets weaned at the average age of 28, 27 and 25 days were subjected to three trials to compare the effectiveness of the use of complete feed mixtures for early-weaned piglets (COS 1 and COS 2) and experimentally prepared mixtures lower in protein and higher in energy, in some cases with an addition of carbadox. In the first 14 days after weaning the piglets fed the mixtures with 90 to 95 g less nitrogen compounds in kg had the same body weight gains, higher feed consumption, and 20% lower consumption of nitrogen compounds per kg of gain than had the piglets given the COS 1 mixture. In the subsequent period of six to thirteen days, the production data demonstrated the economic effectiveness of the use of the experimentally prepared mixtures (the condition was that the level of nitrogen compounds did not decrease to 152 g per kg). The improvement of protein conversion through an increase in the ratio of digestible energy to feed protein by 50%, as compared with the COS 1 mixture at the nitrogen-compound content of 200 g per kg, and the possibility of further reduction in nitrogen compound level after 14 days from weaning, indicate the way how to change the system of nutrition in early-weaned piglets. The high-protein commercial mixture, used to-date, causing high uraemia in the piglets, is not suitable, as demonstrated by physiological, health, and particularly economic data.

Animal Feed↗
PubMed2006

Limitation of oxygenic photosynthesis and oxygen consumption by phosphate and organic nitrogen in a hypersaline microbial mat: a microsensor study.

Microbial mats are characterized by high primary production but low growth rates, pointing to a limitation of growth by the lack of nutrients or substrates. We identified compounds that instantaneously stimulated photosynthesis rates and oxygen consumption rates in a hypersaline microbial mat by following the short-term response (c. 6 h) of these processes to addition of nutrients, organic and inorganic carbon compounds, using microsensors. Net photosynthesis rates were not stimulated by compound additions. However, both gross photosynthesis and oxygen consumption were substantially stimulated (by a minimum of 25%) by alanine (1 mM) and glutamate (3.5 mM) as well as by phosphate (0.1 mM). A low concentration of ammonium (0.1 mM) did not affect photosynthesis and oxygen consumption, whereas a higher concentration (3.5 mM) decreased both process rates. High concentrations of glycolate (5 mM) and phosphate (1 mM) inhibited gross photosynthesis but not oxygen consumption, leading to a decrease of net photosynthesis. Photosynthesis was not stimulated by addition of inorganic carbon, nor was oxygen consumption stimulated by organic compounds like glycolate (5 mM) or glucose (5 mM), indicating that carbon was efficiently cycled within the mat. Photosynthesis and oxygen consumption were apparently tightly coupled, because stimulations always affected both processes to the same extent, which resulted in unchanged net photosynthesis rates. These findings illustrate that microsensor techniques, due to their ability to quantify all three processes, can clarify community responses to nutrient enrichment studies much better than techniques that solely monitor net fluxes.

Biosensing Techniques↗
PubMed2000

Bacteriocin production with Lactobacillus amylovorus DCE 471 is improved and stabilized by fed-batch fermentation.

Amylovorin L471 is a small, heat-stable, and hydrophobic bacteriocin produced by Lactobacillus amylovorus DCE 471. The nutritional requirements for amylovorin L471 production were studied with fed-batch fermentations. A twofold increase in bacteriocin titer was obtained when substrate addition was controlled by the acidification rate of the culture, compared with the titers reached with constant substrate addition or pH-controlled batch cultures carried out under the same conditions. An interesting feature of fed-batch cultures observed under certain culture conditions (constant feed rate) is the apparent stabilization of bacteriocin activity after obtaining maximum production. Finally, a mathematical model was set up to simulate cell growth, glucose and complex nitrogen source consumption, and lactic acid and bacteriocin production kinetics. The model showed that bacterial growth was dependent on both the energy and the complex nitrogen source. Bacteriocin production was growth associated, with a simultaneous bacteriocin adsorption on the producer cells dependent on the lactic acid accumulated and hence the viability of the cells. Both bacteriocin production and adsorption were inhibited by high concentrations of the complex nitrogen source.

Bacteriocins↗
PubMed1993

Methane consumption in temperate and subarctic forest soils: rates, vertical zonation, and responses to water and nitrogen.

Rates of methane consumption were measured in subarctic coniferous and temperate mixed-hardwood forest soils, using static chambers and intact soil cores. Rates at both sites were generally between 1 and 3 mg of CH(4) m day and decreased with increasing soil water contents above 20%. Addition of ammonium (1 mumol g of soil) strongly inhibited methane oxidation in the subarctic soils; a lesser inhibition was observed for temperate forest samples. The response to nitrogen additions occurred within a few hours and was probably due to physiological changes in the active methane-consuming populations. Methane consumption in soils from both sites was stratified vertically, with a pronounced subsurface maximum. This maximum was coincident with low levels of both nitrate and ammonium in the mixed-hardwood forest soil.

Journal Article↗
PubMed2001

Kinetic analysis of growth and xanthan gum production with Xanthomonas campestris on sucrose, using sequentially consumed nitrogen sources.

A batch fermentation strategy using Xanthomonas campestris ATCC 13951 for xanthan gum production has been established in which all essential medium components are supplied at the onset. This has been achieved using sucrose as sole sugar feedstock. Sequential consumption of nitrogen sources (soybean hydrolysates, ammonium and nitrate salts) was observed to facilitate the further optimisation of the medium. Biomass accumulation was limited by phosphate availability. Xanthan yields of more than 60% (grams of xanthan per gram of sugar) have been obtained with constant acetyl content. However, pyruvyl substitution decreased as the growth rate declined, due to the metabolic constraints specific to phosphate depletion. High rates of carbon conversion into xanthan were observed throughout the culture and the ATP/ADP ratio was not affected by the decline in the specific growth rate.

Adenosine Diphosphate↗
PubMed1999

Effects of total dietary nitrogen and nitrogen form on the development of xylophagous leafhoppers

The influence of primary nutrients on the development of the leafhopper Homalodisca coagulata (Say) was examined using Glycine max (L.) Merrill subjected to treatments using different forms of nitrogen fertilization (urea and nitrate) and inoculation with Rhizobium bacteria. Concentrations of amino acids, organic acids, carbohydrates, and ureides in xylem fluid varied with treatment; differences were most pronounced in young plants (6 weeks after planting), and subsided as plants aged. Plants receiving urea fertilization had lower concentrations of organic nitrogen and carbon, but more balanced profiles of amino acids. Leafhoppers on urea-fertilized plants had much higher success in development (62 to 87% survival to adult stage) than H. coagulata developing on nitrate-fertilized plants (31-42%). The sex ratio of successfully developed adults varied greatly with treatments, indicating that female survival was much higher on urea-fertilized plants. Males and females utlilized diets differently as indicated by the carbon and nitrogen content of adult carcasses. Consumption rates and nitrogen assimilation efficiencies were higher for young (third instar) leafhoppers on urea-fertilized plants. Instar duration and total time of development were not affected by treatment. Highest rates of success in development on diets providing the lowest (yet most balanced) concentrations of total nitrogen, amino acids, and organic compounds underscored the importance of nutrient balance for leafhopper development. Arch. Copyright 1999 Wiley-Liss, Inc.

Journal Article↗
PubMedDate not supplied

[Behavior of Candida albicans during a period of nutritional deprivation. Preliminary results].

Cells of Candida albicans, after 24 hours of growth in YM, were starved, alternatively, in citrate buffer, physiological solution, MMS deprived of glucose or ammonium sulphate. The eventual growth was monitored by determining the absorbance at 675 nm. Simultaneously, the cell morphology was also controlled. In a second series of experiments, the C. albicans cells taken from YM were starved for 72 hours in one of the mediums as stated above, and then reinoculated in MMS liquid without, alternatively, glucose or ammonium sulphate. Again the eventual growth was monitored as in the above method. The achieved results indicate the presence of a reserve of nitrogen, which can be utilized when a source of C is given to the cell. We therefore discuss the apparent lack of glucidic reserve and we propose a method for the consumption of nitrogen reserve. The aim of the work is to define how to obtain cells that contain the smallest amount possible of endogenous reserve.

Ammonium Sulfate↗
PubMed1999

Metabolic changes in children with severe traumatic injuries.

INTRODUCTION: Combined traumatic injuries are the leading cause for more than half the cases of lethal outcome in childhood. Trauma triggers a series of endocrinic and metabolic changes commonly known as acute metabolic stress. The hypermetabolic and hypercatabolic condition which develops as a result contributes to the high morbidity and mortality rates in children with traumatic injuries. METHODS: Twenty five children (16 boys and 9 girls aged 4-15 years) were recruited from the patients admitted for treatment to the Department of Pediatric Anesthesia and Intensive Care at the Clinic of Pediatric Surgery in the Higher Medical Institute--Plovdiv, between 1994 and 1998. All children had severe combined trauma. Of these 20 (80%) presented with severe craniocerebral trauma; they were comatose with Glasgow Coma Scale Score of 7.3 +/- 4.3 (Sx = 3.59); the children were on mechanical ventilation and total parenteral nutrition. Energy expenditure was measured using computerised metabolic monitor Deltatrac II. VO2, VCO2, RQ, energy expenditure (MEE), oxygen consumption and nitrogen excretion levels were monitored. RESULTS: The mean energy expenditure measured during the first, second and third 24-hour period was 50.04 kcal/kg/d-1, 50.54 kcal/kg/d-1 and 51.38 kcal/kg/d-1, respectively; the respiratory quotient was 0.81 +/- 0.0114 Sd, the oxygen consumption index 7.32 +/- 0.08 Sd ml/min/m2. The energy expenditure calculated by the Fleisch formula was 42.38 +/- 1.24 kcal/kg/d-1, (Sx = 6.19); this value differed statistically significantly from the value we measured (50.63 +/- 1.31, Sx = 6.57, p < 0.0001), the injury correction factor (ICF) was calculated to be 1.22 +/- 0.02 Sd. CONCLUSIONS: Actual energy expenditure in children with severe traumatic injuries is considerably higher than that calculated by formulae. Based on our results we recommend that the energy and substrate intake to be increased above the values calculated by formulae by a coefficient of 1.22 which is the measured correction factor. Thus the increased energy requirements will be met and the patients' prognosis will be improved.

Adolescent↗
PubMed2000

Response to nitrogen starvation in Corynebacterium glutamicum.

Proteins strongly synthesized in Corynebacterium glutamicum during nitrogen restriction were examined by two-dimensional gel electrophoresis and microsequencing. Two main groups of enzymes were identified beside miscellaneous proteins, enzymes involved (i) in protein synthesis, and (ii) in carbon metabolism. Biochemical measurements revealed an increase of oxygen consumption during nitrogen starvation, indicating an enhanced energy demand of the cells. By Northern hybridizations, an increased transcription for the gap and fda genes upon nitrogen deprivation was shown.

Amino Acid Sequence↗
PubMed1998

[Effect of different nitrogen concentrations on the growth and contents of berberine in rhizome of Coptis chinensis Franch].

OBJECTIVE: Selecting the best N concentrations for the growth of the Chinese goldthread(Coptis chinensis). METHOD: Employing sand culture procedures. RESULT: The symptoms of shortage of nitrogen were reduced in low N(1/5 N) solution, but the new roots and aerial parts were adversely affected in over nitrogen solution(2 N); the activity of NR in leaves and the content of berberine in rhizome were also low in 2 N solution; the range of optimum N concentrations for growth and high contents of effective components is 1/2 N to 1 N. CONCLUSION: The consumption of nitrogen by Coptis chinensis is lower in the period of maximum contents of effective components in rhizome than in the period of luxuriant growing of the plant.

Berberine↗
PubMed2003

[Oxygen-limited autotrophic nitrification and denitrification--a novel technology for biological nitrogen removal].

Oxygen-limited autotrophic nitrification and denitrification (OLAND) is a biological nitrogen removal process coupled with partial nitrification and anaerobic ammonium oxidation. In our study, the nitrification was blocked at nitrite stage by controlling the dissolved oxygen concentration at 0.1-0.3 mg.L-1, and then, the denitrification proceeded, with the residual ammonium at the partial nitrification stage as electron donor. As a completely autotrophic nitrification-denitrification process, the OLAND was of many advantages (e.g., low energy consumption, high nitrogen removal rate and small footprint of system), and suitable in particular for treating low COD/NH4(+)-N ratio wastewater. It has become one of the most prosperous and practicable biological nitrogen removal technologies. The recent research of OLAND was reviewed, and its microbial mechanism as well as its applicable prospect was remarked in this paper.

Ammonia↗
PubMed2005

Use of slow filtration columns to assess oxygen respiration, consumption of dissolved organic carbon, nitrogen transformations, and microbial parameters in hyporheic sediments.

Biogeochemical processes mediated by microorganisms in river sediments (hyporheic sediments) play a key role in river metabolism. Because biogeochemical reactions in the hyporheic zone are often limited to the top few decimetres of sediments below the water-sediment interface, slow filtration columns were used in the present study to quantify biogeochemical processes (uptakes of O2, DOC, and nitrate) and the associated microbial compartment (biomass, respiratory activity, and hydrolytic activity) at a centimetre scale in heterogeneous (gravel and sand) sediments. The results indicated that slow filtration columns recreated properly the aerobic-anaerobic gradient classically observed in the hyporheic zone. O2 and NO3- consumptions (256 +/- 13 microg of O2 per hour and 14.6 +/- 6.1 microg of N-NO3- per hour) measured in columns were in the range of values measured in different river sediments. Slow filtration columns also reproduced the high heterogeneity of the hyporheic zone with the presence of anaerobic pockets in sediments where denitrification and fermentation processes occurred. The respiratory and hydrolytic activities of bacteria were strongly linked with the O2 consumption in the experimental system, highlighting the dominance of aerobic processes in our river sediments. In comparison with these activities, the bacterial biomass (protein content) integrated both aerobic and anaerobic processes and could be used as a global microbial indicator in our system. Finally, slow filtration columns are an appropriate tool to quantify in situ rates of biogeochemical processes and to determine the relationship between the microbial compartment and the physico-chemical environment in coarse river sediments.

Bacteria, Aerobic↗
PubMed2001

Production of oxalic acid from sugar beet molasses by formed nitrogen oxides.

Production of oxalic acid from sugar beet molasses was developed in a series of three reactors. Nitrogen oxides formed were used to manufacture oxalic acid in the second and third reactor. Parameters affecting the reaction were determined to be, air flow rate, temperature, the amount of V2O5 catalyst and the concentrations of molasses and H2SO4. The maximum yields in the second and third reactors were 78.9% and 74.6% of theoretical yield, respectively. Also, kinetic experiments were performed and the first-order rate constants were determined for the glucose consumption rate. Nitrogen oxides in off-gases from the final reactor were absorbed in water and concentrated sulphuric acid and reused in the following reactors giving slightly lower yields under similar conditions. In this novel way, it was possible to recover NO(x) and to prevent air pollution. Meanwhile, it was possible to reduce the unit cost of reactant for oxalic acid production. A maximum 77.5% and 74.1% of theoretical yield was obtained by using the absorption solutions with NO(x).

Air↗
PubMed1979

Nitrogen-fixing capacity of Azotobacter as affected by the type and depth of substrate.

Sixty isolates, representing the different types of azotobacters in Egyptian soils, were studied for their N2-fixing capacity. When A. chroococcum and A. vinelandii were grown in shallow layers of N-deficient liquid medium, nitrogen gains ranged from 48 to 92 and from 20 to 120 ppm with efficiencies of N2-fixation from 15.8 to 50.0 and from 16.6 to 21.2 mg N fixed/g C oxidized, respectively. Culturing in deep layers generally lowered the nitrogen gains and the oxidation of carbon, but at different rates, resulting in the increase of the efficiency of N2-fixation by 2--78%, indicating that the depth of the liquid medium has a definite effect on the outcome of N2-fixation. In another experiment, A. vinelandii was grown in increasing depths of liquid or solid substrates and consequently at variable ratios of surface area: depth. In liquid medium, maximum counts, sugar consumption, and nitrogen gains were detected in the widest surface area: depth ratio, but the efficiency of N2-fixation increased with the narrowing of the ratio. In sand cultures an opposite trend was observed.

Aerobiosis↗
PubMed2002

Nitric oxide is consumed, rather than conserved, by reaction with oxyhemoglobin under physiological conditions.

Although irreversible reaction of NO with the oxyheme of hemoglobin (producing nitrate and methemoglobin) is extremely rapid, it has been proposed that, under normoxic conditions, NO binds preferentially to the minority deoxyheme to subsequently form S-nitrosohemoglobin (SNOHb). Thus, the primary reaction would be conservation, rather than consumption, of nitrogen oxide. Data supporting this conclusion were generated by using addition of a small volume of a concentrated aqueous solution of NO to a normoxic hemoglobin solution. Under these conditions, however, extremely rapid reactions can occur before mixing. We have thus compared bolus NO addition to NO generated homogeneously throughout solution by using NO donors, a more physiologically relevant condition. With bolus addition, multiple hemoglobin species are formed (as judged by visible spectroscopy) as well as both nitrite and nitrate. With donor, only nitrate and methemoglobin are formed, stoichiometric with the amount of NO liberated from the donor. Studies with increasing hemoglobin concentrations reveal that the nitrite-forming reaction (which may be NO autoxidation under these conditions) competes with reaction with hemoglobin. SNOHb formation is detectable with either bolus or donor; however, the amounts formed are much smaller than the amount of NO added (less than 1%). We conclude that the reaction of NO with hemoglobin under normoxic conditions results in consumption, rather than conservation, of NO.

Hemoglobins↗