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Sample records for calcium nitrate inhibitor

  1. Nitrates

    Science.gov (United States)

    ... Blockers Angiotensin-Converting Enzyme (ACE) Inhibitors Antiarrhythmics Anticoagulants Antiplatelet Therapy Aspirin Beta-Blockers Blood Thinners Calcium Channel Blockers Digitalis Medicines Diuretics Inotropic Agents Statins, Cholesterol-Lowering Medicines Nitrates Disclaimer The information ...

  2. Effects of Calcium Lignosulfonate and Silicic Acid on Ammonium Nitrate Degradation

    Directory of Open Access Journals (Sweden)

    Ahmet Ozan Gezerman

    2014-01-01

    Full Text Available Ammonium nitrate salts are the most commonly used nitrogenous fertilizers in industry. However, storage of ammonium nitrate is problematic, since its initial properties can decline because of environmental factors, leading to large economic losses. In this study, in order to prevent the caking and degradation of ammonium nitrate, an alternative composition with additional calcium lignosulfonate and silicic acid was studied. The resulting fertilizer was analyzed by screening analysis, ion chromatography, and electron microscopy methods.

  3. Do proton pump inhibitors decrease calcium absorption?

    Science.gov (United States)

    Hansen, Karen E; Jones, Andrea N; Lindstrom, Mary J; Davis, Lisa A; Ziegler, Toni E; Penniston, Kristina L; Alvig, Amy L; Shafer, Martin M

    2010-12-01

    Proton pump inhibitors (PPIs) increase osteoporotic fracture risk presumably via hypochlorhydria and consequent reduced fractional calcium absorption (FCA). Existing studies provide conflicting information regarding the direct effects of PPIs on FCA. We evaluated the effect of PPI therapy on FCA. We recruited women at least 5 years past menopause who were not taking acid suppressants. Participants underwent three 24-hour inpatient FCA studies using the dual stable isotope method. Two FCA studies were performed 1 month apart to establish baseline calcium absorption. The third study occurred after taking omeprazole (40 mg/day) for 30 days. Each participant consumed the same foods during all FCA studies; study meals replicated subjects' dietary habits based on 7-day diet diaries. Twenty-one postmenopausal women ages 58 ± 7 years (mean ± SD) completed all study visits. Seventeen women were white, and 2 each were black and Hispanic. FCA (mean ± SD) was 20% ± 10% at visit 1, 18% ± 10% at visit 2, and 23% ± 10% following 30 ± 3 days of daily omeprazole (p = .07, ANOVA). Multiple linear regression revealed that age, gastric pH, serum omeprazole levels, adherence to omeprazole, and 25-hydroxyvitamin D levels were unrelated to changes in FCA between study visits 2 and 3. The 1,25-dihydroxyvitamin D(3) level at visit 2 was the only variable (p = .049) associated with the change in FCA between visits 2 and 3. PPI-associated hypochlorhydria does not decrease FCA following 30 days of continuous use. Future studies should focus on identifying mechanisms by which PPIs increase the risk of osteoporotic fracture.

  4. Effect of inhibitors on macroscopical oxidation kinetics of calcium sulfite

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yi; WANG Li-dong; WANG Xiao-ming; LI Qiang-wei; XU Pei-yao

    2005-01-01

    In the presence of inhibitors, the macroscopical oxidation kinetics of calcium sulfite, the main byproduct in wet limestone scrubbing, was studied for the first time by adding different inhibitors and varying pH, concentration of calcium sulfite, oxygen partial pressure, concentration of inhibitors and temperature. The mathematical model about the general oxidation reaction was established,which was controlled by three steps involving dissolution of calcium sulfite, mass transfer of oxygen and chemical reaction in the solution.It was concluded that the general reaction was controlled by mass transfer of oxygen under uncatalyzed conditions, while it was controlled by dissolution of calcium sulfite after adding three kinds of inhibitors. Thus, the theory was provided for investigating the mechanism and oxidation kinetics of sulfite. The beneficial references were also supplied for design of oxidation technics in the wet limestone scrubbing.

  5. Potential genesis and implications of calcium nitrate in Antarctic snow

    Science.gov (United States)

    Mahalinganathan, Kanthanathan; Thamban, Meloth

    2016-04-01

    Among the large variety of particulates in the atmosphere, calcic mineral dust particles have highly reactive surfaces that undergo heterogeneous reactions with atmospheric acids contiguously. The association between nssCa2+, an important proxy indicator of mineral dust, and NO3-, a dominant anion in the Antarctic snowpack, was analysed. A total of 41 snow cores ( ˜ 1 m each) that represent snow deposited during 2008-2009 were studied along coastal-inland transects from two different regions in East Antarctica - the Princess Elizabeth Land (PEL) and central Dronning Maud Land (cDML). Correlation statistics showed a strong association (at 99 % significance level) between NO3- and nssCa2+ at the near-coastal sections of both PEL (r = 0.74) and cDML (r = 0.82) transects. Similarly, a strong association between these ions was also observed in snow deposits at the inland sections of PEL (r = 0.73) and cDML (r = 0.84). Such systematic associations between nssCa2+ and NO3- are attributed to the interaction between calcic mineral dust and nitric acid in the atmosphere, leading to the formation of calcium nitrate (Ca(NO3)2) aerosol. Principal component analysis revealed common transport and depositional processes for nssCa2+ and NO3- both in PEL and cDML. Forward- and back-trajectory analyses using HYSPLIT model v. 4 revealed that southern South America (SSA) was an important dust-emitting source to the study region, aided by the westerlies. Particle size distribution showed that over 90 % of the dust was in the range dust particles reached the Antarctic region via long-range transport from the SSA region. We propose that the association between nssCa2+ and NO3- occurs during the long-range transport due to the formation of Ca(NO3)2 rather than to local neutralisation processes. However, the influence of local dust sources from the nunataks in cDML and the contribution of high sea salt in coastal PEL evidently mask such association in the mountainous and coastal regions

  6. Reducing nitrous oxide emissions by changing N fertiliser use from calcium ammonium nitrate (CAN) to urea based formulations.

    Science.gov (United States)

    Harty, M A; Forrestal, P J; Watson, C J; McGeough, K L; Carolan, R; Elliot, C; Krol, D; Laughlin, R J; Richards, K G; Lanigan, G J

    2016-09-01

    The accelerating use of synthetic nitrogen (N) fertilisers, to meet the world's growing food demand, is the primary driver for increased atmospheric concentrations of nitrous oxide (N2O). The IPCC default emission factor (EF) for N2O from soils is 1% of the N applied, irrespective of its form. However, N2O emissions tend to be higher from nitrate-containing fertilisers e.g. calcium ammonium nitrate (CAN) compared to urea, particularly in regions, which have mild, wet climates and high organic matter soils. Urea can be an inefficient N source due to NH3 volatilisation, but nitrogen stabilisers (urease and nitrification inhibitors) can improve its efficacy. This study evaluated the impact of switching fertiliser formulation from calcium ammonium nitrate (CAN) to urea-based products, as a potential mitigation strategy to reduce N2O emissions at six temperate grassland sites on the island of Ireland. The surface applied formulations included CAN, urea and urea with the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) and/or the nitrification inhibitor dicyandiamide (DCD). Results showed that N2O emissions were significantly affected by fertiliser formulation, soil type and climatic conditions. The direct N2O emission factor (EF) from CAN averaged 1.49% overall sites, but was highly variable, ranging from 0.58% to 3.81. Amending urea with NBPT, to reduce ammonia volatilisation, resulted in an average EF of 0.40% (ranging from 0.21 to 0.69%)-compared to an average EF of 0.25% for urea (ranging from 0.1 to 0.49%), with both fertilisers significantly lower and less variable than CAN. Cumulative N2O emissions from urea amended with both NBPT and DCD were not significantly different from background levels. Switching from CAN to stabilised urea formulations was found to be an effective strategy to reduce N2O emissions, particularly in wet, temperate grassland.

  7. Sandia National Laboratories Small-Scale Sensitivity Testing (SSST) Report: Calcium Nitrate Mixtures with Various Fuels.

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Jason Joe [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2014-07-01

    Based upon the presented sensitivity data for the examined calcium nitrate mixtures using sugar and sawdust, contact handling/mixing of these materials does not present hazards greater than those occurring during handling of dry PETN powder. The aluminized calcium nitrate mixtures present a known ESD fire hazard due to the fine aluminum powder fuel. These mixtures may yet present an ESD explosion hazard, though this has not been investigated at this time. The detonability of these mixtures will be investigated during Phase III testing.

  8. Interactions of calcium nitrate with pyranosides in water: A 13C NMR study

    Science.gov (United States)

    Zhuo, Kelei; Wang, Yaping; Zhao, Yang; Liu, Qian; Wang, Jianji

    2008-11-01

    The 13C NMR spectra of methyl α- and β- D-galactopyranosides, and methyl α- and β- D-glucopyranosides were recorded and show that the Δ( δC-4) values for methyl α- and β- D-galactopyranosides increase most rapidly, whereas those for methyl α- and β- D-glucopyranosides vary hardly with increasing molality of calcium nitrate. It can be concluded that ax-OH-4 interacts more strongly with Ca 2+ than eq-OH-4 group, namely, the Ca 2+ ion interaction with ax-OH-4 leads to a stronger deshielding of the C-4 atom. Compared with other C atoms, the chemical shifts of both C-1 and C-5 atoms in these two types of glycosides decrease relatively rapidly as molality of calcium nitrate increases, indicating that the nitrate ion attractions for these glycosides cause a relatively strong enhancing shielding effect of C-1 and C-5 atoms.

  9. [Calcium suppletion for patients who use gastric acid inhibitors: calcium citrate or calcium carbonate?].

    NARCIS (Netherlands)

    Jonge, H.J. de; Gans, R.O.; Huls, G.A.

    2012-01-01

    Various calcium supplements are available for patients who have an indication for calcium suppletion. American guidelines and UpToDate recommend prescribing calcium citrate to patients who use antacids The rationale for this advice is that water-insoluble calcium carbonate needs acid for adequate ab

  10. The influence of scale inhibitors on calcium oxalate

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    Gill, J.S. [Calgon Corp., Pittsburgh, PA (United States)

    1999-11-01

    Precipitation of calcium oxalate is a common occurrence in mammalian urinary tract deposits and in various industrial processes such as paper making, brewery fermentation, sugar evaporation, and tannin concentration. Between pH 3.5 to 4.5 the driving force for calcium oxalate precipitation increases almost by three fold. It is a complicated process to predict both the nature of a deposit and at which stage of a multi-effect evaporator a particular mineral will deposit, as this depends on temperature, pH, total solids, and kinetics of mineralization. It is quite a challenge to inhibit calcium oxalate precipitation in the pH range of 4--6. Al{sup 3+} ions provide excellent threshold inhibition in this pH range and can be used to augment traditional inhibitors such as polyphosphates and polycarboxylates.

  11. Synthesis of porous poly(acrylamide hydrogels using calcium carbonate and its application for slow release of potassium nitrate

    Directory of Open Access Journals (Sweden)

    2009-05-01

    Full Text Available Porous poly(acrylamide was synthesized using calcium carbonate microparticles and subsequent acid treatment to remove the calcium carbonate. Methylenebisacrylamide and ammonium persulfate/sodium metabisulfite were used as crosslinking agent and redox initiator, respectively. The porous structure of resulted hydrogels was confirmed using SEM micrographs. The effect of methylenebisacrylamide concentration and calcium carbonate amount on the swelling of the hydrogels was investigated. The results showed that the effect of methylenebisacrylamide and calcium carbonate variables on the swelling is reverse. The hydrogels were subsequently utilized for the loading of potassium nitrate. Potassium nitrate as active agent was loaded into hydrogels and subsequently the release of this active agent was investigated. In these series of investigation, the effect of content of loading, methylenebisacrylamide and calcium carbonate amount on the release of potassium nitrate from hydrogels was investigated.

  12. Nitrated and Brominated Narcotine and its Cleaved Adduct as Butyrylcholinesterase Inhibitors

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    M. A. Abbasi

    2013-09-01

    Full Text Available Narcotine is a very antitussive agent and its modification may lead to some more biological activities. In this presented paper, narcotine (1 was first subjected to nitration and bromination to yield nitrated narcotine (2 and brominated narcotine (3. It was further made to react with phenylchloroformate (6 to give a cleaved addition product 4. This adduct 4 was further nitrated and brominated to yield substituted derivatives 5 and 6, respectively. The structure elucidation of the synthesized compounds was processed via IR, EI-MS and 1H-NMR spectra. These were also screened against butyrylcholinesterase enzyme and were found to the moderate inhibitors of butyrylcholinesterase except nitrated product, 2, of narcotine (1.

  13. Calcium pentosan polysulfate is a multifaceted exosite inhibitor of aggrecanases.

    Science.gov (United States)

    Troeberg, Linda; Fushimi, Kazunari; Khokha, Rama; Emonard, Hervé; Ghosh, Peter; Nagase, Hideaki

    2008-10-01

    Degradation of the cartilage proteoglycan aggrecan is a key early event in the development of osteoarthritis. Adamalysin with thrombospondin motifs (ADAMTS) -4 and ADAMTS-5 are considered to be the main enzymes responsible for aggrecan breakdown, making them attractive drugs targets. Here we show that calcium pentosan polysulfate (CaPPS), a chemically sulfated xylanopyranose from beechwood, is a multifaceted exosite inhibitor of the aggrecanases and protects cartilage against aggrecan degradation. CaPPS interacts with the noncatalytic spacer domain of ADAMTS-4 and the cysteine-rich domain of ADAMTS-5, blocking activity against their natural substrate aggrecan with inhibitory concentration 50 values of 10-40 nM but only weakly inhibiting hydrolysis of a nonglycosylated recombinant protein substrate. In addition, CaPPS increased cartilage levels of tissue inhibitor of metalloproteinases-3 (TIMP-3), an endogenous inhibitor of ADAMTS-4 and -5. This was due to the ability of CaPPS to block endocytosis of TIMP-3 mediated by low-density lipoprotein receptor-related protein. CaPPS also increased the affinity of TIMP-3 for ADAMTS-4 and -5 by more than 100-fold, improving the efficacy of TIMP-3 as an aggrecanase inhibitor. Studies with TIMP-3-null mouse cartilage indicated that CaPPS inhibition of aggrecan degradation is TIMP-3 dependent. These unique properties make CaPPS a prototypic disease-modifying agent for osteoarthritis.

  14. Role of barium nitrate on the sulfur fixation of calcium oxide`

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, the effect of Ba(NO3)2 on the efficiency of sulfur fixation of calcium oxide during coal combustion was studied. The results showed that addition of barium nitrate to the CaO can enhance the sulfur removal rate of CaO significantly. The X-ray diffraction spectrum of residual ash of coal added some sulfur fixative expressed that Ba2+ can form a compound of Ba-Al-Si-O which encloses the CaSO4 to prevent it's decomposition, so Ba2+ can improve the action of sulfur fixation of CaO. The combustion character os the original coal and original coal added sulfur fixative was researched with thermal-gravity analyzer and the results expressed that adding some sulfur fixative to the coal will make the combustion character of coal change little.

  15. The effect of cattle slurry in combination with nitrate and the nitrification inhibitor dicyandiamide on in situ nitrous oxide and dinitrogen emissions

    Science.gov (United States)

    McGeough, K. L.; Laughlin, R. J.; Watson, C. J.; Müller, C.; Ernfors, M.; Cahalan, E.; Richards, K. G.

    2012-12-01

    A field study was conducted to determine the effect of the nitrification inhibitor dicyandiamide (DCD) on N2O and N2 emissions after cattle slurry (CS) application in the presence of nitrate (NO3) fertiliser on seven different occasions (between March 2009 and March 2011). N2O emissions from CS in the presence of NO3 fertiliser were very high (0.4-8.7% of applied N) over a 20-day period, under mild moist conditions. Emissions were significantly larger from the CS treatment compared to an NH4+-N source, supplying the same rate of N as in the slurry. This study supports the view that organic fertilisers should not be applied at the same time as nitrate-based fertilisers, as significant increases in N2O emissions occur. The average N2O mole fraction (N2O/(N2O + N2)) over all seven application dates was 0.34 for CSNO3 compared to 0.24 for the NH4ClNO3 treatment, indicating the dominance of N2 emissions. The rate of nitrification in CSNO3 was slower than in NH4ClNO3, and DCD was found to be an effective nitrification inhibitor in both treatments. However, as N2O emissions were found to be predominantly associated with the NO3 pool, the effect of DCD in lowering N2O emissions is limited in the presence of a NO3 fertiliser. To obtain the maximum cost-benefit of DCD in lowering N2O emissions, under mild moist conditions, it should not be applied to a nitrate containing fertiliser (e.g. ammonium nitrate or calcium ammonium nitrate), and therefore the application of DCD should be restricted to ammonium-based organic or synthetic fertilisers.

  16. Solubility of PdI/sub 2/ in nitrate and perchlorate solutions. [For use in spent fuels processing; solvents are water, nitric acid, calcium nitrate, and sodium perchlorate

    Energy Technology Data Exchange (ETDEWEB)

    Horner, D.E.; Mailen, J.C.; Bigelow, H.R.

    1976-01-01

    This paper reports the solubilities of PdI/sub 2/ as measured in nitric acid by a tracer technique and in water, calcium nitrate, and sodium perchlorate solutions by a specific ion electrode technique. The tracer technique measures all the soluble iodine species, whereas the specific ion electrode measures only simple iodide ions (I/sup -/). When compared on the basis of ionic strength, the values obtained in the nitrate solutions by the two methods were in reasonable agreement. The solubilities in perchlorate solution were much higher than in nitrate, possibly because of ionic equilibria involving Pd/sup 4 +/, but this was not resolved in this work. The activity product constant, K/sub ap(PdI/sub 2/)/ = (2.5 +- 0.4) x 10/sup -23/ (25/sup 0/C), was calculated from PdI/sub 2/ solubility in water. With this value and the standard electrode potentials from the literature, the free energy of formation for PdI/sub 2/ was calculated to be --13.6 kcal/mol.

  17. The effect of cattle slurry in combination with nitrate and the nitrification inhibitor dicyandiamide on in situ nitrous oxide and dinitrogen emissions

    Directory of Open Access Journals (Sweden)

    K. L. McGeough

    2012-12-01

    Full Text Available A field study was conducted to determine the effect of the nitrification inhibitor dicyandiamide (DCD on N2O and N2 emissions after cattle slurry (CS application in the presence of nitrate (NO3 fertiliser on seven different occasions (between March 2009 and March 2011. N2O emissions from CS in the presence of NO3 fertiliser were very high (0.4–8.7% of applied N over a 20-day period, under mild moist conditions. Emissions were significantly larger from the CS treatment compared to an NH4+-N source, supplying the same rate of N as in the slurry. This study supports the view that organic fertilisers should not be applied at the same time as nitrate-based fertilisers, as significant increases in N2O emissions occur. The average N2O mole fraction (N2O/(N2O + N2 over all seven application dates was 0.34 for CSNO3 compared to 0.24 for the NH4ClNO3 treatment, indicating the dominance of N2 emissions. The rate of nitrification in CSNO3 was slower than in NH4ClNO3, and DCD was found to be an effective nitrification inhibitor in both treatments. However, as N2O emissions were found to be predominantly associated with the NO3 pool, the effect of DCD in lowering N2O emissions is limited in the presence of a NO3 fertiliser. To obtain the maximum cost-benefit of DCD in lowering N2O emissions, under mild moist conditions, it should not be applied to a nitrate containing fertiliser (e.g. ammonium nitrate or calcium ammonium nitrate, and therefore the application of DCD should be restricted to ammonium-based organic or synthetic fertilisers.

  18. FIXED COMBINATION OF THE CALCIUM CHANNEL BLOCKER LERCANIDIPINE AND ANGIOTENSIN CONVERTING ENZYME INHIBITOR ENALAPRIL: POSSIBILITY OF USAGE

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    O. D. Ostroumova

    2013-01-01

    Full Text Available Data on the updated approach to the choice of two-component antihypertensive combinations for different clinical situations are presented. Advantages and indications for combination of an angiotensin converting enzyme (ACE inhibitor and dihydropyridine calcium antagonist are considered. Data on the efficacy and safety of the combination of calcium antagonist of the third generation, lercanidipine, and ACE inhibitor, enalapril, are presented.

  19. Synthesis of organic nitrates of luteolin as a novel class of potent aldose reductase inhibitors.

    Science.gov (United States)

    Wang, Qi-Qin; Cheng, Ning; Zheng, Xiao-Wei; Peng, Sheng-Ming; Zou, Xiao-Qing

    2013-07-15

    Aldose reductase (AR) plays an important role in the design of drugs that prevent and treat diabetic complications. Aldose reductase inhibitors (ARIs) have received significant attentions as potent therapeutic drugs. Based on combination principles, three series of luteolin derivatives were synthesised and evaluated for their AR inhibitory activity and nitric oxide (NO)-releasing capacity in vitro. Eighteen compounds were found to be potent ARIs with IC50 values ranging from (0.099±0.008) μM to (2.833±0.102) μM. O(7)-Nitrooxyethyl-O(3'),O(4')-ethylidene luteolin (La1) showed the most potent AR inhibitory activity [IC50=(0.099±0.008) μM]. All organic nitrate derivatives released low concentrations of NO in the presence of l-cysteine. Structure-activity relationship studies suggested that introduction of an NO donor, protection of the catechol structure, and the ether chain of a 2-carbon spacer as a coupling chain on the luteolin scaffold all help increase the AR inhibitory activity of the resulting compound. This class of NO-donor luteolin derivatives as efficient ARIs offer a new concept for the development and design of new drug for preventive and therapeutic drugs for diabetic complications.

  20. The nitrate reductase inhibitor, tungsten, disrupts actin microfilaments in Zea mays L.

    Science.gov (United States)

    Adamakis, Ioannis-Dimosthenis S; Panteris, Emmanuel; Eleftheriou, Eleftherios P

    2014-05-01

    Tungsten is a widely used inhibitor of nitrate reductase, applied to diminish the nitric oxide levels in plants. It was recently shown that tungsten also has heavy metal attributes. Since information about the toxic effects of tungsten on actin is limited, and considering that actin microfilaments are involved in the entry of tungsten inside plant cells, the effects of tungsten on them were studied in Zea mays seedlings. Treatments with sodium tungstate for 3, 6, 12 or 24 h were performed on intact seedlings and seedlings with truncated roots. Afterwards, actin microfilaments in meristematic root and leaf tissues were stained with fluorescent phalloidin, and the specimens were examined by confocal laser scanning microscopy. While the actin microfilament network was well organized in untreated seedlings, in tungstate-treated ones it was disrupted in a time-dependent manner. In protodermal root cells, the effects of tungsten were stronger as cortical microfilaments were almost completely depolymerized and the intracellular ones appeared highly bundled. Fluorescence intensity measurements confirmed the above results. In the meristematic leaf tissue of intact seedlings, no depolymerization of actin microfilaments was noticed. However, when root tips were severed prior to tungstate application, both cortical and endoplasmic actin networks of leaf cells were disrupted and bundled after 24 h of treatment. The differential response of root and leaf tissues to tungsten toxicity may be due to differential penetration and absorption, while the effects on actin microfilaments could not be attributed to the nitric oxide depletion by tungsten.

  1. Does calcium in drinking water modify the association between nitrate in drinking water and risk of death from colon cancer?

    Science.gov (United States)

    Chiu, Hui-Fen; Tsai, Shang-Shyue; Chen, Pei-Shih; Wu, Trong-Neng; Yang, Chun-Yuh

    2011-09-01

    The objective of this study was to explore whether calcium (Ca) levels in drinking water modified the effects of nitrate on colon cancer risk. A matched case-control study was used to investigate the relationship between the risk of death from colon cancer and exposure to nitrate in drinking water in Taiwan. All colon cancer deaths of Taiwan residents from 2003 through 2007 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair-matched to the cases by gender, year of birth and year of death. Information on the levels of nitrate-nitrogen (NO(3)-N) and Ca in drinking water have been collected from Taiwan Water Supply Corporation (TWSC). The municipality of residence for cases and controls was assumed to be the source of the subject's NO(3)-N and Ca exposure via drinking water. We observed evidence of an interaction between drinking water NO(3)-N and Ca intake via drinking water. This is the first study to report effect modification by Ca intake from drinking water on the association between NO(3)-N exposure and risk of colon cancer mortality.

  2. Rapid, high-temperature, field test method for evaluation of geothermal calcium carbonate scale inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Asperger, R.G.

    1986-09-01

    A new test method is described that allows the rapid field testing of calcium carbonate scale inhibitors at 500/sup 0/F (260/sup 0/C). The method evolved from use of a full-flow test loop on a well with a mass flow rate of about 1 x 10/sup 6/ lbm/hr (126 kg/s). It is a simple, effective way to evaluate the effectiveness of inhibitors under field conditions. Five commercial formulations were chosen for field evaluation on the basis of nonflowing, laboratory screening tests at 500/sup 0/F (260/sup 0/C). Four of these formulations from different suppliers controlled calcium carbonate scale deposition as measured by the test method. Two of these could dislodge recently deposited scale that had not age-hardened. Performance-profile diagrams, which were measured for these four effective inhibitors, show the concentration interrelationship between brine calcium and inhibitor concentrations at which the formulations will and will not stop scale formation in the test apparatus. With these diagrams, one formulation was chosen for testing on the full-flow brine line. The composition was tested for 6 weeks and showed a dramatic decrease in the scaling occurring at the flow-control valve. This scaling was about to force a shutdown of a major, long-term flow test being done for reservoir economic evaluations. The inhibitor stopped the scaling, and the test was performed without interruption.

  3. EFFECT OF ELECTROACUPUNCTURE AND CALCIUM-CHANNEL INHIBITORS ON CYTOPLASMIC FREE CALCIUM CONCENTRATION OF MOUSE BRAIN CELLS

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ming-mei; XIE Ji-min; CHEN Min; ZHANG Yan

    2005-01-01

    Objective: To study the effect of electroacupuncture (EA) and Verapamil and Nifedipine (calcium channel inhibitors) on free calcium concentrations of cells and intrasynaptosomes in hypothalamus (HT), periaqueductual grey matter (PAG) and hippocampus (HIP) of mice. Methods: The female ICR mice were randomly divided into control, EA, CaCl2 and CaCl2+EA groups (n=8 in each group). Pain threshold was detected by using radiation-heat irradiation-induced tail flick method. EA (8 Hz, a suitable stimulating strength, dense-sparse waves and duration of 30 min) was applied to"Shuigou" (水沟 GV 26) and "Chengjiang" (承浆CV 24). CaCl2 (10 μL, 0.2 μmol/L) was injected into the lateral cerebral ventricle of mice after EA. The concentrations of cytosolic free calcium ([Ca2+]i) in HIP, PAG, HT cell suspension specimen and hippocampal intrasynaptosome suspension of mice were determined by the fluorescent calcium indicator Fura-2-AM and a spectrofluorometer. Results: During EA analgesia, the intracellular free [Ca2+]i in HT and PAG specimens and intrsynaptosomal [Ca2+]i of the 3 cerebral regions decreased considerably (P<0.05~0.01), but that in hippocampal cell suspension increased significantly (P<0.01) in comparison with control group. The concentrations of hippocampal intrasynaptosomal free [Ca2+]i decreased significantly after adding Verapamil and Nifedipine to the extracted hippocampal intrasynaptosomal specimen. Microinjection of CaCl2 into lateral ventricle had no apparent influence on degree of analgesia (DA)% and intracellular and intrasynapsotomal [Ca2+]i, but significantly lower DA% and reduce changes of cytosolic and intrasynaptosomal [Ca2+]i induced by EA stimulation. Conclusion: Calcium ion in the neurons and intrasynaptosome of HT, PAG and HIP is involved in electroacupuncture analgesia.

  4. Protein arginine deiminase 2 binds calcium in an ordered fashion: implications for inhibitor design.

    Science.gov (United States)

    Slade, Daniel J; Fang, Pengfei; Dreyton, Christina J; Zhang, Ying; Fuhrmann, Jakob; Rempel, Don; Bax, Benjamin D; Coonrod, Scott A; Lewis, Huw D; Guo, Min; Gross, Michael L; Thompson, Paul R

    2015-04-17

    Protein arginine deiminases (PADs) are calcium-dependent histone-modifying enzymes whose activity is dysregulated in inflammatory diseases and cancer. PAD2 functions as an Estrogen Receptor (ER) coactivator in breast cancer cells via the citrullination of histone tail arginine residues at ER binding sites. Although an attractive therapeutic target, the mechanisms that regulate PAD2 activity are largely unknown, especially the detailed role of how calcium facilitates enzyme activation. To gain insights into these regulatory processes, we determined the first structures of PAD2 (27 in total), and through calcium-titrations by X-ray crystallography, determined the order of binding and affinity for the six calcium ions that bind and activate this enzyme. These structures also identified several PAD2 regulatory elements, including a calcium switch that controls proper positioning of the catalytic cysteine residue, and a novel active site shielding mechanism. Additional biochemical and mass-spectrometry-based hydrogen/deuterium exchange studies support these structural findings. The identification of multiple intermediate calcium-bound structures along the PAD2 activation pathway provides critical insights that will aid the development of allosteric inhibitors targeting the PADs.

  5. Measuring calcium, potassium, and nitrate in plant nutrient solutions using ion-selective electrodes in hydroponic greenhouse of some vegetables.

    Science.gov (United States)

    Vardar, Gökay; Altıkatoğlu, Melda; Ortaç, Deniz; Cemek, Mustafa; Işıldak, İbrahim

    2015-01-01

    Generally, the life cycle of plants depends on the uptake of essential nutrients in a balanced manner and on toxic elements being under a certain concentration. Lack of control of nutrient levels in nutrient solution can result in reduced plant growth and undesired conditions such as blossom-end rot. In this study, sensitivity and selectivity tests for various polyvinylchloride (PVC)-based ion-selective membranes were conducted to identify those suitable for measuring typical concentration ranges of macronutrients, that is, NO(3-), K(+), and Ca(2+), in hydroponic solutions. The sensitivity and selectivity of PVC-membrane-based ion-selective sensors prepared with tetradodecylammoniumnitrate for NO(3-), valinomycin for K(+), and Ca ionophore IV for Ca(2+) were found to be satisfactory for measuring NO(3-), K(+), and Ca(2+) ions in nutrient solutions over typical ranges of hydroponic concentrations. Potassium, calcium, and nitrate levels that were utilized by cucumber and tomato seedlings in the greenhouse were different. The findings show that tomato plants consumed less amounts of nitrate than cucumber plants over the first 2 months of their growth. We also found that the potassium intake was higher than other nutritional elements tested for all plants.

  6. Comparative evaluation of a dentifrice containing calcium sodium phosphosilicate to a dentifrice containing potassium nitrate for dentinal hypersensitivity: A clinical study

    Directory of Open Access Journals (Sweden)

    Tanya Satyapal

    2014-01-01

    Full Text Available Background: Calcium sodium phosphosilicate is a recently introduced desensitizing agent which acts by occluding the dentinal tubules and also resists acid decalcification. This study was designed to assess the efficacy of a new toothpaste containing 5% calcium sodium phosphosilicate for the treatment of dentinal hypersensitivity and also compare it with 5% potassium nitrate. Materials and Methods: Sixty patients with the chief complaint of dentinal hypersensitivity were enrolled and randomly divided into two groups. The visual analog scale (VAS scores were taken for water and air stimuli at baseline, 3 weeks after usage of the respective toothpaste, and 3 weeks after discontinuation of the respective toothpaste. Results: Both the groups showed reduction in hypersensitivity scores at 3 weeks and 6 weeks for air stimulus and cold water. The calcium sodium phosphosilicate group, however, showed significantly reduction in hypersensitivity compared to the potassium nitrate group at any time point for both measures of hypersensitivity. Conclusion: The 5% calcium sodium phosphosilicate group showed immense reduction in dentinal hypersensitivity symptoms. The 5% calcium sodium phosphosilicate showed prolonged effects even after discontinuation as compared to 5% potassium nitrate, due to its dentinal tubular occlusion property.

  7. Ceria nanoparticles vis-à-vis cerium nitrate as corrosion inhibitors for silica-alumina hybrid sol-gel coating

    Science.gov (United States)

    Lakshmi, R. V.; Aruna, S. T.; Sampath, S.

    2017-01-01

    The present work provides a comparative study on the corrosion protection efficiency of defect free sol-gel hybrid coating containing ceria nanoparticles and cerium nitrate ions as corrosion inhibitors. Less explored organically modified alumina-silica hybrid sol-gel coatings are synthesized from 3-glycidoxypropyltrimethoxysilane and aluminium-tri-sec-butoxide. The microemulsion derived nanoparticles and the hybrid coatings are characterized and compared with coatings containing cerium nitrate. Corrosion inhibiting capability is assessed using electrochemical impedance spectroscopy. Scanning Kelvin probe measurements are also conducted on the coatings for identifying the apparent corrosion prone regions. Detailed X-ray photoelectron spectroscopy (XPS) analysis is carried out to comprehend the bonding and corrosion protection rendered by the hybrid coatings.

  8. Molecular dynamics simulation on the interaction mechanism between polymer inhibitors and calcium phosphate

    Indian Academy of Sciences (India)

    Jian-Ping Zeng; Xiao-Rong Qian; Feng-He Wang; Jing-Ling Shao; Yun-Shan Bai

    2014-05-01

    Investigation on the microscopic interaction between polymer inhibitors and calcium phosphate contributes to the understanding of their scale inhibition mechanism. The results obtained may provide a theoretical guidance to developing new scale inhibitors. In this study, molecular dynamics simulations have been performed to simulate the interaction between hydrolyzed polymaleic anhydride (HPMA), polyaspartic acid (PASP), polyepoxysuccinic acid (PESA), polyacrylic acid (PAA) and the (001) and (110) surfaces of hydroxyapatite (HA) crystal with and without water. Results show that the simulations of polymer inhibitors and the (001) surface of HA with water is closer to the actual situation. On the same HA (001), binding energy of four polymer inhibitors with water has the order of HPMA > PASP > PESA > PAA. On the different surface of HA, the binding energy does not vary much between the same polymer and the two surfaces of HA. But, deformation energies of the same polymer with and without water vary widely. Pair correlation function of Ca (HA)-O (-C=O) implies that the Ca-O bonds formed between the calcium atoms of HA crystal and oxygen atoms of the carboxyl groups in polymers, and water molecules change the distances between polymer inhibitors and HA crystal. The system of polymer-HA is mainly contributed by the non-bond interaction. Polymer inhibitors do not interact directly with HA crystal, but indirectly through the interactions between inhibitor-H2O and H2O-HA. Water molecules cannot be ignored when the interaction models are constructed, i.e., solvent effect must be considered.

  9. Effects of a new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate and potassium leaching in two soils.

    Science.gov (United States)

    Wu, Shao-Fu; Wu, Liang-Huan; Shi, Qi-Wei; Wang, Zhong-Qiang; Chen, Xian-You; Li, Yong-Shan

    2007-01-01

    In this study, soil column was used to study the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate (NO3(-)-N) and potassium (K) leaching in the sandy loam soil and clay loam soil. The results showed that DMPP with ammonium sulphate nitrate (ASN) ((NH4)2SO4 and NH4NO3) or urea could reduce NO3(-)-N leaching significantly, whereas ammonium (NH4(+)-N) leaching increased slightly. In case of total N (NO3(-)-N+NH4(+)-N), losses by leaching during the experimental period (40 d) were 37.93 mg (urea), 31.61 mg (urea+DMPP), 108.10 mg (ASN), 60.70 mg (ASN+DMPP) in the sandy loam soil, and 30.54 mg (urea), 21.05 mg (urea+DMPP), 37.86 mg (ASN), 31.09 mg (ASN+DMPP) in the clay loam soil, respectively. DMPP-amended soil led to the maintenance of relatively high levels of NH4(+)-N and low levels of NO3(-)-N in soil, and nitrification was slower. DMPP supplementation also resulted in less potassium leached, but the difference was not significant except the treatment of ASN and ASN+DMPP in the sandy loam soil. Above results indicate that DMPP is a good nitrification inhibitor, the efficiency of DMPP seems better in the sandy loam soil than in the clay loam soil and lasts longer.

  10. Effects of the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate and potassium leaching in two soils

    Institute of Scientific and Technical Information of China (English)

    WU Shao-fu; WU Liang-huan; SHI Qi-wei; WANG Zhong-qiang; CHEN Xian-you; LI Yong-shan

    2007-01-01

    In this study, soil column was used to study the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on nitrate (NO3--N) and potassium (K) leaching in the sandy loam soil and clay loam soil. The results showed that DMPP with ammonium sulphate nitrate (ASN) ((NH4)2SO4 and NH4NO3) or urea could reduce NO3--N leaching significantly, whereas ammonium (NH4+-N) leaching increased slightly. In case of total N (NO3--N+NH4+-N), losses by leaching during the experimental period (40 d) were 37.93 mg (urea), 31.61 mg (urea+DMPP), 108.10 mg (ASN), 60.70 mg (ASN+DMPP) in the sandy loam soil, and 30.54 mg (urea), 21.05 mg (urea+DMPP), 37.86 mg (ASN), 31. 09 mg (ASN+DMPP) in the clay loam soil, respectively. DMPP-amended soil led to the maintenance of relatively high levels of NH4+-N and low levels of NO3--N in soil, and nitrification was slower. DMPP supplementation also resulted in potassium leached less, but the difference was not significant except the treatment ASN and ASN+DMPP in the sandy loam soil. Above results indicate that DMPP is a good nitrification inhibitor, the efficiency of DMPP seems better in the sandy loam soil than in the clay loam soil and lasts longer.

  11. [Discovering L-type calcium channels inhibitors of antihypertensive drugs based on drug repositioning].

    Science.gov (United States)

    Liang, Ying-xi; He, Yu-su; Jiang, Lu-di; Yue, Qiao-xin; Cui, Shuai; Bin, Li; Ye, Xiao-tong; Zhang, Xiao-hua; Zhang, Yang-ling

    2015-09-01

    This study was amid to construct the pharmacophore model of L-type calcium channel antagonist in the application of screening Drugbank and TCMD. This paper repositions the approved drugs resulting from virtual screening and discusses the relocation-based drug discovery methods, screening antihypertensive drugs with L-type calcium channel function from TCMD. Qualitative hypotheses wre generated by HipHop separately on the basis of 12 compounds with antagonistic action on L-type calcium channel expressed in rabbit cardiac muscle. Datebase searching method was used to evaluate the generated hypotheses. The optimum hypothesis was used to search Drugbank and TCMD. This paper repositions the approved drugs and evaluates the antihypertensive effect of the chemical constituent of traditional Chinese medicine resulting from virtual screening by the matching score and literature. The results showed that optimum qualitative hypothesis is with six features, which were two hydrogen-bond acceptors, four hydrophobic groups, and the CAI value of 2.78. Screening Drugbank achieves 93 approved drugs. Screening TCMD achieves 285 chemical constituents of traditional Chinese medicine. It was concluded that the hypothesis is reliable and can be used to screen datebase. The approved drugs resulting from virtual screening, such as pravastatin, are potentially L-type calcium channels inhibitors. The chemical constituents of traditional Chinese medicine, such as Arctigenin III and Arctigenin are potentially antihypertensive drugs. It indicates that Drug Repositioning based on hypothesis is possible.

  12. Investigation of scale inhibition mechanisms based on the effect of scale inhibitor on calcium carbonate crystal forms

    Institute of Scientific and Technical Information of China (English)

    ZHANG GuiCai; GE JiJiang; SUN MingQin; PAN BinLin; MAO Tao; SONG ZhaoZheng

    2007-01-01

    To probe the scale inhibition mechanisms, calcium carbonate scale occurring before and after the addition of scale inhibitors was collected. The results from scale SEM confirm that, without scale inhibitor, calcium carbonate scale shows rhombohedron and hexagon, which are the characteristic feathers of calcite. After addition of inhibitors, morphology of scale is changed, and the more efficient the scale inhibitor is, the more greatly the morphology is modified. To elucidate the scale constitute, they were further analyzed by FT-IR, XRD. Besides calcite, vaterite and aragonite occur in calcium carbonate scale after addition of inhibitors, and the higher scale inhibition efficiency is, the more vaterite presents in scale. It can be concluded that the alteration of morphology is ascribed to the change of crystal form. There are three stages in the crystallizing process including occurrence and disappearing of unstable phase, occurrence and disappearing of metastable phase, development of stable phase. Without scale inhibitors, metastable phases usually transform into stable phase, thus the main constitute of formed scale is calcite. When scale inhibitors are added, both formation and transformation of metastable phases are inhibited, which results in the occurrence of aragonite and vaterite. From the fact that more vaterite presents in scale with a more efficient scale inhibitor added, we can see that the function of scale inhibitor is realized mainly by controlling the crystallizing process at the second stage.

  13. Investigation of scale inhibition mechanisms based on the effect of scale inhibitor on calcium carbonate crystal forms

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    To probe the scale inhibition mechanisms,calcium carbonate scale occurring before and after the ad- dition of scale inhibitors was collected.The results from scale SEM confirm that,without scale inhibitor, calcium carbonate scale shows rhombohedron and hexagon,which are the characteristic feathers of calcite.After addition of inhibitors,morphology of scale is changed,and the more efficient the scale inhibitor is,the more greatly the morphology is modified.To elucidate the scale constitute,they were further analyzed by FT-IR,XRD.Besides calcite,vaterite and aragonite occur in calcium carbonate scale after addition of inhibitors,and the higher scale inhibition efficiency is,the more vaterite presents in scale.It can be concluded that the alteration of morphology is ascribed to the change of crystal form. There are three stages in the crystallizing process including occurrence and disappearing of unstable phase,occurrence and disappearing of metastable phase,development of stable phase.Without scale inhibitors,metastable phases usually transform into stable phase,thus the main constitute of formed scale is calcite.When scale inhibitors are added,both formation and transformation of metastable phases are inhibited,which results in the occurrence of aragonite and vaterite.From the fact that more vaterite presents in scale with a more efficient scale inhibitor added,we can see that the function of scale inhibitor is realized mainly by controlling the crystallizing process at the second stage.

  14. ACE inhibitors and calcium antagonists in the treatment of congestive heart failure

    DEFF Research Database (Denmark)

    Hansen, J F

    1995-01-01

    The increased mortality after myocardial infarction is related to the risk of reinfarction, sudden death, and the development and progression of heart failure; in congestive heart failure it is due to the progression of heart failure and sudden death. ACE inhibitors have been proven to prevent...... cardiovascular events, especially the progression of heart failure, in postinfarct patients with reduced ejection fraction and heart failure in the SAVE and AIRE trials. In patients with congestive heart failure, ACE inhibitor treatment has prevented cardiovascular death and reduced morbidity due to progressive...... heart failure in the SOLVD trials. In post-myocardial infarction patients, the calcium antagonist nifedipine did not affect mortality or morbidity; diltiazem improved prognosis in patients without congestive heart failure and in patients with non-Q-wave infarction; and verapamil improved prognosis...

  15. Inhibitors of arachidonate-regulated calcium channel signaling suppress triggered activity induced by the late sodium current.

    Science.gov (United States)

    Wolkowicz, Paul; Umeda, Patrick K; Sharifov, Oleg F; White, C Roger; Huang, Jian; Mahtani, Harry; Urthaler, Ferdinand

    2014-02-05

    Disturbances in myocyte calcium homeostasis are hypothesized to be one cause for cardiac arrhythmia. The full development of this hypothesis requires (i) the identification of all sources of arrhythmogenic calcium and (ii) an understanding of the mechanism(s) through which calcium initiates arrhythmia. To these ends we superfused rat left atria with the late sodium current activator type II Anemonia sulcata toxin (ATXII). This toxin prolonged atrial action potentials, induced early afterdepolarization, and provoked triggered activity. The calmodulin-dependent protein kinase II (CaMKII) inhibitor KN-93 (N-[2-[[[3-(4-chlorophenyl)-2-propenyl]methylamino]methyl]phenyl]-N-(2-hydroxyethyl)-4-methoxybenzenesulphon-amide) suppressed ATXII triggered activity but its inactive congener KN-92 (2-[N-(4-methoxy benzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzylamine) did not. Neither drug affected normal atrial contractility. Calcium entry via L-type channels or calcium leakage from sarcoplasmic reticulum stores are not critical for this type of ectopy as neither verapamil ((RS)-2-(3,4-dimethoxyphenyl)-5-{[2-(3,4-dimethoxyphenyl)ethyl]-(methyl)amino}-2-prop-2-ylpentanenitrile) nor ryanodine affected ATXII triggered activity. By contrast, inhibitors of the voltage independent arachidonate-regulated calcium (ARC) channel and the store-operated calcium channel specifically suppressed ATXII triggered activity without normalizing action potentials or affecting atrial contractility. Inhibitors of cytosolic calcium-dependent phospholipase A2 also suppressed triggered activity suggesting that this lipase, which generates free arachidonate, plays a key role in ATXII ectopy. Thus, increased left atrial late sodium current appears to activate atrial Orai-linked ARC and store operated calcium channels, and these voltage-independent channels may be unexpected sources for the arrhythmogenic calcium that underlies triggered activity.

  16. Regulation of NKG2D-ligand cell surface expression by intracellular calcium after HDAC-inhibitor treatment

    DEFF Research Database (Denmark)

    Jensen, Helle; Hagemann-Jensen, Michael Henrik; Lauridsen, Felicia Kathrine Bratt;

    2013-01-01

    -cells. We further show that secretion and cell surface binding of the calcium-regulating protein galectin-1 is enhanced upon HDAC-inhibitor treatment of melanoma cells. However, binding of galectin-1 to cell surface glycoproteins was not critical for constitutive or HDAC-inhibitor induced MICA/B and ULBP2......In this study we demonstrate that histone deacetylase (HDAC)-inhibitor mediated cell surface expression of the structural different NKG2D-ligands MICA/B and ULBP2 is calcium-dependent. Treatment with the calcium chelator EGTA inhibited constitutive as well as HDAC-inhibitor induced MICA/B and ULBP2...... cell surface expression on melanoma cells and Jurkat T-cells. A NKG2D-dependent cytolytic assay and staining with a recombinant NKG2D-Fc fusion protein showed that calcium chelation impaired the functional ability of NKG2D-ligands induced by HDAC-inhibitor treatment. The HDAC-inhibitor induced cell...

  17. Effect of fixed-dose ACE-inhibitor/calcium channel blocker combination therapy vs. ACE-inhibitor monotherapy on arterial compliance in hypertensive patients with type 2 diabetes.

    Science.gov (United States)

    Winer, Nathaniel; Folker, Amy; Murphy, Julie A; Hung, Elena; Bard, Mara; Perkelvald, Alexander; Sowers, James R; Bakris, George L

    2005-01-01

    Assessment of vascular compliance may be a useful measurement of the clinical effects of antihypertensive treatment. Both angiotensin-converting enzyme (ACE) inhibitors and calcium channel blockers are known to improve vascular elasticity. A study was performed to test the hypothesis that combined therapy with an ACE inhibitor and a calcium channel blocker would have additive benefits on vascular compliance at similar levels of blood pressure (BP), as compared with monotherapy with an ACE inhibitor. This 12-week, double-blind study was a substudy of a larger clinical hypertension study conducted in patients with hypertension and type 2 diabetes. Subjects (N = 20) were randomized to either a fixed-dose combination of amlodipine besylate/benazepril HCl or to enalapril monotherapy. BP, heart rate, large- and small-vessel compliance, systemic vascular resistance, and urinary microalbumin excretion were assessed at baseline and after treatment. Both treatments were similarly effective in lowering BP, reducing systemic vascular resistance, and decreasing urinary microalbumin excretion. Improvement in large-vessel compliance was significantly greater among subjects who received ACE-inhibitor/calcium channel blocker combination therapy (52%) as compared with those who received ACE-inhibitor monotherapy (32%; p < 0.05). No significant change in small-vessel compliance was observed with either treatment. Greater improvement in large-vessel compliance with combination therapy was independent of BP lowering.

  18. Effect of angiotensin converting enzyme inhibitor on the calcium transients and calcium handling proteins in ventricular myocytes from rats with heart failure

    Institute of Scientific and Technical Information of China (English)

    WANG Li-chun; ZENG Wu-tao; LIU Jun; DONG Yu-gang; TANG An-li; FENG Chong; MA Hong; HE Jian-gui; LIAO Xin-xue; CHEN Wen-fang; LENG Xiu-yu; MA Li; MAI Wei-yi; TAO Jun

    2005-01-01

    Background Chronic heart failure (CHF) is associated with calcium transients and calcium handling proteins. Angiotensin converting enzyme (ACE) inhibitor has been demonstrated to have beneficial effect on CHF. Yet studies addressed to the relationship between ACE inhibitor and calcium transients in CHF are rare. The aim of this study was to investigate the influence of ACE inhibitor (perindopril) on the contractility and calcium transients and calcium handling proteins in ventricular myocytes from rats with experimental heart failure.Results The fraction of cell shortening (FS%) and [Ca2+]imax (nmol/L) were significantly reduced in group CHF-C compared with group PS (FS%: 7.51±1.15 vs 13.21±1.49;[Ca2+]imax:330.85±50.05 vs 498.16±14.07; both P<0.01), and restored at least partially in CHF-T group. In CHF-C group, the left ventricular mRNA of NCX1 and PLB were significantly upregulated in comparing with PS group (RNCX1/β-Actin: 0.51±0.12 vs 0.19±0.06, P<0.01; RPLB/β-Actin: 0.26±0.12 vs 0.20±0.08, P<0.05), while SERCA2 mRNA was downregulated (0.48±0.10 vs 0.80±0.11, P<0.01). The mRNA levels of NCX1 and SERCA2 in CHF-T group were between the CHF-C and PS group, and the differences of the latter two groups were significant (all P<0.05). In CHF-C and CHF-T groups, the protein expression of NCX1 were 1.141±0.047 and 1.074±0.081 times of that in PS group respectively (both P<0.05), and SERCA2 protein levels were 0.803±0.100 and 0.893±0.084 times of that in PS group respectively (both P<0.05). The protein expression of NCX1 and SERCA2 in the CHF-C and CHF-T groups is significantly different (both P<0.05).Conclusion ACE inhibitor could improve cardiac function of failing heart through directly enhancing the contractility of single cardiomyocyte, and these effects are probably mediated by its roles in preventing the deleterious changes of calcium transients and calcium handling proteins in CHF.

  19. Comparative Behaviour of Nitrite and Nitrate for the Protection of Rebar Corrosion

    Science.gov (United States)

    Ahmad, Altaf; Kumar, Anil

    2016-10-01

    Corrosion of rebar steel due to environmental causes has been studied through various approaches, and among the protection techniques use of inhibitors has gained encouragement. Nitrites and nitrates of sodium have gained sufficient scientific coverage. Recently, nitrites and nitrates of calcium have been verified in some studies, which, however, needs further experimentation through different angles. Simple polarization technique has been utilized in the present study to compare inhibitive efficiency of these salts of sodium and calcium, which indicate that calcium salts are more efficient.

  20. The neuronal nitric oxide synthase inhibitor NANT blocks acetaminophen toxicity and protein nitration in freshly isolated hepatocytes.

    Science.gov (United States)

    Banerjee, Sudip; Melnyk, Stepan B; Krager, Kimberly J; Aykin-Burns, Nukhet; Letzig, Lynda G; James, Laura P; Hinson, Jack A

    2015-12-01

    3-Nitrotyrosine (3NT) in liver proteins of mice treated with hepatotoxic doses of acetaminophen (APAP) has been postulated to be causative in toxicity. Nitration is by a reactive nitrogen species formed from nitric oxide (NO). The source of the NO is unclear. iNOS knockout mice were previously found to be equally susceptible to APAP toxicity as wildtype mice and iNOS inhibitors did not decrease toxicity in mice or in hepatocytes. In this work we examined the potential role of nNOS in APAP toxicity in hepatocytes using the specific nNOS inhibitor NANT (10 µM)(N-[(4S)-4-amino-5-[(2-aminoethyl)amino]pentyl]-N'-nitroguanidinetris (trifluoroacetate)). Primary hepatocytes (1 million/ml) from male B6C3F1 mice were incubated with APAP (1mM). Cells were removed and assayed spectrofluorometrically for reactive nitrogen and oxygen species using diaminofluorescein (DAF) and Mitosox red, respectively. Cytotoxicity was determined by LDH release into media. Glutathione (GSH, GSSG), 3NT, GSNO, acetaminophen-cysteine adducts, NAD, and NADH were measured by HPLC. APAP significantly increased cytotoxicity at 1.5-3.0 h. The increase was blocked by NANT. NANT did not alter APAP mediated GSH depletion or acetaminophen-cysteine adducts in proteins which indicated that NANT did not inhibit metabolism. APAP significantly increased spectroflurometric evidence of reactive nitrogen and oxygen formation at 0.5 and 1.0 h, respectively, and increased 3NT and GSNO at 1.5-3.0 h. These increases were blocked by NANT. APAP dramatically increased NADH from 0.5-3.0 h and this increase was blocked by NANT. Also, APAP decreased the Oxygen Consumption Rate (OCR), decreased ATP production, and caused a loss of mitochondrial membrane potential, which were all blocked by NANT.

  1. Effective mitigation of nitrate leaching and nitrous oxide emissions in intensive vegetable production systems using a nitrification inhibitor, dicyandiamide

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Min; Sun, Xuecheng; Hu, Chengxiao; Tan, Qiling; Zhao, Changsheng [Huazhong Agricultural Univ., Wuhan (China). Key Lab. of Subtropical Agricultural Resources and Environment; Di, Hong J. [Lincoln Univ., Christchurch (New Zealand). Center for Soil and Environment Research

    2011-07-15

    Vegetable production is one of the most intensive agricultural systems with high rates of nitrogen (N) fertilizer use and irrigation, conditions conducive for nitrate (NO{sub 3}{sup -}) leaching, and nitrous oxide (N{sub 2}O) emissions. The objective of this study was to determine the effectiveness of a nitrification inhibitor, dicyandiamide (DCD), in decreasing NO{sub 3}{sup -} leaching and N{sub 2}O emissions in vegetable production systems. Twenty-four undisturbed soil monolith lysimeters (610 mm in diameter; 700 mm in depth; surface area, 0.29 m{sup 2}) with two different soils, Huangzongrang (alfisol) and Chaotu (fluvisols), were collected and installed in a field lysimeter facility in Central China under irrigated vegetable production conditions. Urea fertilizer was applied at 650 kg N ha{sup -1}, and DCD was applied at 10 kg ha{sup -1} to the lysimeters planted with three kinds of vegetables (capsicum, Capsicum annuum L.; amaranth, Amaranthus mangostanus L.; radish, Raphanus sativus L.). The results showed that DCD reduced NO3- leaching by 58.5% and 36.2% and N{sub 2}O emissions factor by 83.8% and 72.7% in the two soils. The average NO{sub 3}{sup -}-N concentration in the drainage water was decreased from 4.9 mg NL{sup -1} to 2.3 mg NL{sup -1} and from 4.4 mg NL{sup -1} to 3.3 mg NL{sup -1}, in the Huangzongrang and Chaotu soils, respectively. In addition to the environmental benefits, the use of DCD also increased the yields of capsicum and radish in alfisol soil significantly (P < 0.01); only the amaranth yield in fluvisol soil was declined (P < 0.01), and the other vegetables yields were not affected. Total N concentrations of the three vegetables were increased significantly (P < 0.01) with the application of DCD with urea compared with urea alone. These results showed that the nitrification inhibitor DCD has the potential to significantly reduce NO{sub 3}{sup -} leaching and N{sub 2}O emissions and to make vegetable farming more environmentally

  2. Calcium antagonists and converting enzyme inhibitors reduce renal injury by different mechanisms.

    Science.gov (United States)

    Dworkin, L D; Benstein, J A; Parker, M; Tolbert, E; Feiner, H D

    1993-04-01

    Both glomerular hypertension and hypertrophy have been associated with the development of glomerular injury in models of hypertension and reduced renal mass. The purpose of this study was to examine the effects of antihypertensive therapy on these parameters in the remnant kidney model of progressive glomerular sclerosis. Rats underwent 5/6 nephrectomy and were randomly assigned to receive either no therapy, the calcium entry blocker (CEB), nifedipine, or the angiotensin converting enzyme inhibitor (CEI), enalapril. Administration of either drug was associated with a reduction in systemic blood pressure and in the severity of glomerular injury assessed eight weeks after renal ablation. Micropuncture studies four weeks after ablation revealed that systemic and glomerular capillary pressure were high in untreated remnant kidney rats and reduced by enalapril. Administration of nifedipine was associated with a decline in systemic pressure, however, plasma renin levels increased, causing efferent arteriolar vasoconstriction and persistence of glomerular hypertension. Morphometric analysis showed that kidney weight, glomerular volume and glomerular capillary radius were lower in nifedipine treated rats than in the other two groups, indicating that the CEB, but not enalapril, inhibited the hypertrophic response to ablation of renal mass. Therefore, both CEIs and CEBs reduce glomerular injury in rats with remnant kidneys but they may act by different mechanisms. CEI reduce glomerular capillary pressure while CEBs inhibit compensatory kidney growth.

  3. Exploring NMR ensembles of calcium binding proteins: Perspectives to design inhibitors of protein-protein interactions

    Directory of Open Access Journals (Sweden)

    Craescu Constantin T

    2011-05-01

    Full Text Available Abstract Background Disrupting protein-protein interactions by small organic molecules is nowadays a promising strategy employed to block protein targets involved in different pathologies. However, structural changes occurring at the binding interfaces make difficult drug discovery processes using structure-based drug design/virtual screening approaches. Here we focused on two homologous calcium binding proteins, calmodulin and human centrin 2, involved in different cellular functions via protein-protein interactions, and known to undergo important conformational changes upon ligand binding. Results In order to find suitable protein conformations of calmodulin and centrin for further structure-based drug design/virtual screening, we performed in silico structural/energetic analysis and molecular docking of terphenyl (a mimicking alpha-helical molecule known to inhibit protein-protein interactions of calmodulin into X-ray and NMR ensembles of calmodulin and centrin. We employed several scoring methods in order to find the best protein conformations. Our results show that docking on NMR structures of calmodulin and centrin can be very helpful to take into account conformational changes occurring at protein-protein interfaces. Conclusions NMR structures of protein-protein complexes nowadays available could efficiently be exploited for further structure-based drug design/virtual screening processes employed to design small molecule inhibitors of protein-protein interactions.

  4. Synthetic Methods for the Preparation of a Functional Analogue of Ru360, a Potent Inhibitor of Mitochondrial Calcium Uptake.

    Science.gov (United States)

    Nathan, Sarah R; Pino, Nicholas W; Arduino, Daniela M; Perocchi, Fabiana; MacMillan, Samantha N; Wilson, Justin J

    2017-03-20

    The mixed-valent oxo-bridged ruthenium complex [(HCO2)(NH3)4Ru(μ-O)Ru(NH3)4(O2CH)](3+), known as Ru360, is a selective inhibitor of mitochondrial calcium uptake. Although this compound is useful for studying the role of mitochondrial calcium in biological processes, its widespread availability is limited because of challenges in purification and characterization. Here, we describe our investigations of three different synthetic methods for the preparation of a functional analogue of this valuable compound. We demonstrate that this analogue, isolated from our procedures, exhibits potent mitochondrial calcium uptake inhibitory properties in permeabilized HeLa cells and in isolated mitochondria.

  5. Cost containment for treating hypertension in African Americans: impact of a combined ACE inhibitor-calcium channel blocker.

    Science.gov (United States)

    Kountz, D S

    1997-07-01

    The use of calcium channel blockers (CCBs) and angiotensin-converting enzyme (ACE) inhibitors has increased dramatically over the last 10 years and now accounts for 60% to 70% of all new antihypertensive prescriptions. Even though these two classes are efficacious, they are costly. Combined ACE inhibitor/CCB therapy (amlodipine-benazepril) was introduced in 1995. An analysis was done to assess the potential financial impact of substituting this agent for patients being treated with on ACE inhibitor/CCB combination. A pharmaceutical profile review of prescriptions during October 1995 was performed on 219 randomly selected patients enrolled in a Medicaid managed care program. Eighty-four profiles were analyzed; 24% of patients were on a combination ACE inhibitor/CCB regimen with an average monthly cost of $135. If the single agent amlodipine-benazepril with an average monthly cost of $45 (all strengths) was substituted, the savings would be considerable: $1080 per patient per year and $1,080,000 annualized for the calculated number of hypertensives on combination therapy in our network of 15,000 patients. Therapeutic substitution is one method of achieving cost containment in managed care. The cost differential between separately prescribed CCBs and ACE inhibitors and amlodipine-benazepril is significant. Compliance also should be enhanced as the patient would need to take only one pill daily. Once a patient has been maintained on a stable dose of a CCB/ACE inhibitor, substitution with amlodipine-benazepril should be considered.

  6. Effects of Nitrogen Fertilizer with Nitrification Inhibitor DMPP (3,4-Dimethylpyrazole phosphate) on Nitrate Accumulation and Quality of Cabbage (Brassica campastris L.ssp.pekinesis)

    Institute of Scientific and Technical Information of China (English)

    XU Chao; WU Liang-huan; JU Xiao-tang; ZHANG Fu-suo

    2004-01-01

    To assess the effects of N fertilizer ammonium sulphate nitrate [(NH4)2SO4 plus NH4NO3;ASN] with the new nitrification inhibitor (NI) 3, 4-dimethylpyrazole phosphate (DMPP)(ASN+DMPP) on yield, nitrate accumulation, and quality of cabbage (Brassica campastrisL. ssp. pekinesis), two field trials were carried out under various soil-climatic conditions in Jinhua City and Xinchang County, Zhejiang Province of China in 2002.Results showed that DMPP could increase the mean yield by + 2.0 t ha-1 in Jinhua, +5.5 t ha-1 in Xinchang, decrease NO3--N content by -9.4% in Jinhua, -7.3% in Xinchang and improve nutritional quality by increasing vitamin C (VC), soluble sugar, K, Fe, Zn contents significantly.

  7. Infusum Daun Alpukat Sebagai Inhibitor Kristalisasi Kalsium Oksalat pada Ginjal (THE AVOCADO LEAVES INFUSUM AS INHIBITOR ON RENAL CALCIUM OXALATE CRYSTALIZATION

    Directory of Open Access Journals (Sweden)

    Rini Madyastuti

    2016-01-01

    Full Text Available Urine crystal is a crystal nucleus which tend to form urine stone. The case of urine stone seems to beincreased every year. Crystallization could induce acute tubular necrosis which impact on renal dysfunction.The signs of this condition are high level of urea, creatinine and decrease glomerulus filtration rate. Theobjective of this research was to evaluate the effects of infusum Persea americana Mill as an inhibitorcrystallization which induced by ethylene glycol on white male rats. 20 male rats were divided into 4groups; K1 as negative group received only distilled water ad libitum, K2 as positive group receiveddistilled water containing ethylene glycol, K3 (dose 5% and K4 (dose 10% as treatment groups receivedwater containing ethylene glycol and avocado leaves infusion. Phytochemsitry screening of infusion avocadoleaves consisted of flavonoid, saponin, tanine and quinone. Result of analysis showed that the level ofureum and creatinine on K2 was higher than K3 and K4 group. The increased level could be inhibited byinfusion avocado leaves. The measurement of glomerular filtration rate in treatment groups wassignificantly different (p<0.05. Descriptive histopathology observation showed that renal lesio in grouptreatment (K3 and K4 were declined. Large crystal calcium oxalate on K2 group was observed by usingpolarized microscope, whereas small crystal calcium oxalate were seen in the infusion of avocado leavesgroups. These result showed the ability of infusion of avocado leaves as an inhibitor on the growth ofcrystallization calcium oxalate

  8. Inhibitors of protein kinase C prevent enhancement of calcium current and action potentials in peptidergic neurons of Aplysia.

    Science.gov (United States)

    Conn, P J; Strong, J A; Kaczmarek, L K

    1989-02-01

    Following brief stimulation of an afferent pathway, the bag cell neurons of Aplysia undergo a dramatic change in excitability, resulting in a prolonged discharge of spontaneous action potentials. During the discharge, the action potentials of the bag cell neurons become enhanced in height and width. The afterdischarge triggers release of neuroactive peptides that initiate egg-laying behavior in this animal. Evidence suggests that changes in excitability of the bag cell neurons may be mediated by activation of protein kinase C (PKC) and cAMP-dependent protein kinase (cAMP-PK). PKC activators, such as the phorbol ester TPA (12-O-tetradecanoyl-13-phorbol acetate), enhance the amplitude of action potentials in isolated bag cell neurons in cell culture. These agents act by unmasking a previously covert species of voltage-dependent calcium channel resulting in an increase in calcium current. In the accompanying paper (Conn et al., 1989), we showed that H-7, a protein kinase inhibitor, inhibits the effect of TPA, and is a selective inhibitor of PKC relative to cAMP-PK in these cells. We now report that another PKC inhibitor, sphinganine, also inhibits the effect of TPA on action potential height and calcium current in cultured bag cell neurons, and that N-acetylsphinganine, an inactive sphinganine analog, fails to inhibit the effects of PKC activators. Although both H-7 and sphinganine prevent the effects of TPA when added prior to TPA addition, neither compound reverses the effects of TPA when added after the action potentials have already become enhanced by TPA.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Current concepts in combination therapy for the treatment of hypertension: combined calcium channel blockers and RAAS inhibitors

    Directory of Open Access Journals (Sweden)

    Alberto F Rubio-Guerra

    2009-11-01

    Full Text Available Alberto F Rubio-Guerra1, David Castro-Serna2, Cesar I Elizalde Barrera2, Luz M Ramos-Brizuela21Metabolic and Research Clinic, 2Internal Medicine Department, Hospital General de Ticomán SS DF, MéxicoAbstract: Recent guidelines for the management of hypertension recommend target blood pressures <140/90 mmHg in hypertensive patients, or <130/80 mmHg in subjects with diabetes, chronic kidney disease, or coronary artery disease. Despite the availability and efficacy of antihypertensive drugs, most hypertensive patients do not reach the recommended treatment targets with monotherapy, making combination therapy necessary to achieve the therapeutic goal. Combination therapy with 2 or more agents is the most effective method for achieving strict blood pressure goals. Fixed-dose combination simplifies treatment, reduces costs, and improves adherence. There are many drug choices for combination therapy, but few data are available about the efficacy and safety of some specific combinations. Combination therapy of calcium antagonists and inhibitors of the renin-angiotensin-aldosterone system (RAAS are efficacious and safe, and have been considered rational by both the JNC 7 and the 2007 European Society of Hypertension – European Society of Cardiology guidelines for the management of arterial hypertension. The aim of this review is to discuss some relevant issues about the use of combinations with calcium channel blockers and RAAS inhibitors in the treatment of hypertension.Keywords: hypertension, calcium channel blockers, renin-angiotensin-aldosterone system inhibitors, fixed-dose combination, adherence

  10. The histone deacetylase inhibitor SAHA induces HSP60 nitration and its extracellular release by exosomal vesicles in human lung-derived carcinoma cells.

    Science.gov (United States)

    Campanella, Claudia; D'Anneo, Antonella; Marino Gammazza, Antonella; Caruso Bavisotto, Celeste; Barone, Rosario; Emanuele, Sonia; Lo Cascio, Filippa; Mocciaro, Emanuele; Fais, Stefano; Conway De Macario, Everly; Macario, Alberto J L; Cappello, Francesco; Lauricella, Marianna

    2016-05-17

    HSP60 undergoes changes in quantity and distribution in some types of tumors suggesting a participation of the chaperonin in the mechanism of transformation and cancer progression. Suberoylanilide hydroxamic acid (SAHA), a member of a family of histone deacetylase inhibitors (HDACi), has anti-cancer potential but its interaction, if any, with HSP60 has not been elucidated. We investigated the effects of SAHA in a human lung-derived carcinoma cell line (H292). We analysed cell viability and cycle; oxidative stress markers; mitochondrial integrity; HSP60 protein and mRNA levels; and HSP60 post-translational modifications, and its secretion. We found that SAHA is cytotoxic for H292 cells, interrupting the cycle at the G2/M phase, which is followed by death; cytotoxicity is associated with oxidative stress, mitochondrial damage, and diminution of intracellular levels of HSP60; HSP60 undergoes a post-translational modification and becomes nitrated; and nitrated HSP60 is exported via exosomes. We propose that SAHA causes ROS overproduction and mitochondrial dysfunction, which leads to HSP60 nitration and release into the intercellular space and circulation to interact with the immune system. These successive steps might constitute the mechanism of the anti-tumor action of SAHA and provide a basis to design supplementary therapeutic strategies targeting HSP60, which would be more efficacious than the compound alone.

  11. [Does the diuretic effect of calcium inhibitors play an important role in the hypertensive efficacy?].

    Science.gov (United States)

    Maldonado Martin, A; Gil Extremera, B; Rubio Luengo, M A

    1995-04-08

    Calcium ions play an important role in the pathophysiology of hypertension. Calcium antagonists, a group of first line drugs in the treatment of hypertension, reduce the intracellular content of calcium in vascular smooth muscle cells, and decrease the peripheral vascular resistance and blood pressure. These drugs differ from other vasodilators in that they also have natriuretic effects; thus they can affect the kidney on three levels: Renal haemodynamics are affected by increased renal blood flow, and increased glomerular filtration rate. Changes in the renin-angiotensin system can decrease aldosterone secretion. Finally, they affect sodium management by acting directly on the renal tubule, increasing sodium excretion and inhibiting tubular reabsorption of this ion. The natriuretic effect of calcium antagonists is independent of the subject's sodium balance. The vasodilating action of these drugs is therefore accompanied by a natriuretic effect that makes satisfactory control of hypertension possible without placing the patient on a low-salt or salt-free diet.

  12. High-throughput platform for design and screening of peptides as inhibitors of calcium oxalate monohydrate crystallization

    Science.gov (United States)

    Farmanesh, Sahar; Chung, Jihae; Chandra, Divya; Sosa, Ricardo D.; Karande, Pankaj; Rimer, Jeffrey D.

    2013-06-01

    Crystal growth modifiers present a versatile tool for controlling crystal shape and size. Our work described here focuses on the design and screening of short peptides as inhibitors of calcium oxalate monohydrate (COM) crystals using high-throughput approaches. We designed a small library of 13 peptides containing Ala and Asp amino acids arranged in varying sequences that mimic ubiquitous motifs in natural calcium-binding proteins. Peptides were screened using a quick assay to measure their efficacy for inhibiting COM crystallization. Our results show that subtle variations in the placement of Ala and Asp residues in the peptide sequence can have a profound effect on their inhibition potential. We were able to discover peptide sequences that inhibit COM crystallization more effectively than some of the well-known COM inhibitors, such as citrate. Our results also demonstrate that peptides can be engineered to bind to specific faces of COM crystals. Peptide sequences identified in this work are promising candidates for further development as therapies for biomineral-related diseases, such as kidney stone disease. Collectively, our work establishes new paradigms for the design, synthesis, and screening of peptides for controlling crystal habit with the potential to impact a variety of fields, including drug discovery, advanced materials, catalysis and separations.

  13. Calcium spirulan, an inhibitor of enveloped virus replication, from a blue-green alga Spirulina platensis.

    Science.gov (United States)

    Hayashi, T; Hayashi, K; Maeda, M; Kojima, I

    1996-01-01

    Bioactivity-directed fractionation of a hot H2O extract from a blue-green alga Spirulina platensis led to the isolation of a novel sulfated polysaccharide named calcium spirulan (Ca-SP) as an antiviral principle. This polysaccharide was composed of rhamnose, ribose, mannose, fructose, galactose, xylose, glucose, glucuronic acid, galacturonic acid, sulfate, and calcium. Ca-SP was found to inhibit the replication of several enveloped viruses, including Herpes simplex virus type 1, human cytomegalovirus, measles virus, mumps virus, influenza A virus, and HIV-1. It was revealed that Ca-SP selectively inhibited the penetration of virus into host cells. Retention of molecular conformation by chelation of calcium ion with sulfate groups was suggested to be indispensable to its antiviral effect.

  14. 硝酸还原酶抑制剂钨酸钠对油菜硝态氮积累的影响%Effects of Nitrate Reductase Inhibitor Na2WO4 on Nitrate Accumulation in Oilseed Rape

    Institute of Scientific and Technical Information of China (English)

    杨荣; 邱炜红; 王朝辉; 王小英

    2012-01-01

    采用溶液培养方法,选取硝酸盐积累差异明显的两个油菜品种(低硝态氮积累品种‘红油3号’和高硝态氮积累品种‘中双6号’,研究苗期根系硝酸还原酶(NR)活性被抑制以后两个油菜品种叶片、叶柄和根系中NR活性和硝态氮含量的变化.结果表明:1.0 mmol·L-1的NR活性抑制剂Na2WO4对两个油菜品种的根系NR活性抑制效果最佳;根系NR活性被抑制以后,两个油菜品种的根系NR活性、硝态氮吸收速率均显著下降,而硝态氮含量却显著上升;且Na2WO4对‘中双6号’硝态氮吸收的抑制程度强于其对‘红油3号’的抑制.叶片和叶柄的NR活性变化不显著,但叶柄硝态氮含量显著下降,叶片硝态氮含量稳定,且这一趋势在低积累品种‘红油3号’中表现得更为明显.%A soilless culture (nutrient solution) experiment was conducted to study the effects of nitrate re-ductase inhibitor Na2WO4 on nitrate reductase (NR) activity and NO3"-N content in some organs (including root, leaf, petiole) of two different cultivars (high nitrate-N accumulation type 'Zhongshuang 6' and low nitrate-N accumulation type 'Hongyou 3') oilseed rape (Brassica napus L.) at seedling stage. Results showed that the most appropriate concentration of Na2WO4 was 1.0 mmol-L-1 Na2WO4 significantly decreased NR activity and NO3-N absorption rate in the root of oilseed rape comparing with the control (CK), however, significantly increasing in NO3-N content. High nitrate accumulation type 'Zhongshuang 6' had higher inhibiter efficiency comparing with low nitrate accumulation type 'Hongyou 3'. There were no significant difference on NR activity in leaf and petiole with or without Na2WO4, in contrast, Na2WO4 significantly decreased NO3 -N content in the petiole of oilseed rape, and NO3 -N content in the leaf was almost stable under it treatment, especially in 'Hongyou 3'.

  15. Mechanistic understanding of calcium-phosphonate solid dissolution and scale inhibitor return behavior in oilfield reservoir: formation of middle phase.

    Science.gov (United States)

    Zhang, Ping; Shen, Dong; Ruan, Gedeng; Kan, Amy T; Tomson, Mason B

    2016-08-03

    Phosphonates are an important class of mineral scale inhibitors used for oilfield scale control. By injecting the phosphonate into an oilfield reservoir, calcium-phosphonate precipitate will form and subsequently release the phosphonate into produced water for scale control. In this study, a systematic procedure is developed to mechanistically characterize an acidic calcium-phosphonate amorphous material that is later developed into a middle phase and eventually a crystalline phase. The phosphonate used in this study is diethylenetriamine pentakis (methylene phosphonic acid) (DTPMP). An amorphous calcium-DTPMP solid is precipitated by mixing a calcium-containing solution with a DTPMP solution. The stoichiometry of this initially formed solid can be experimentally confirmed via a static dissolution test. Following another dynamic development test, two additional Ca-DTPMP solid phases, i.e., a middle phase and a crystalline phase have been observed. Electron microscopy and X-ray diffraction were employed to characterize the morphology and crystallinity of different Ca-DTPMP solids of interest. Evidently, the dynamic brine flushing of the Ca-DTPMP solid developed the initially amorphous material into a middle phase solid with an amorphous/microcrystalline structure and eventually into a crystalline material. Furthermore, a dissolution characterization study was carried out to determine the solubility product of the middle phase solid at different conditions. The obtained mechanistic understanding of the Ca-DTPMP solid related to precipitation chemistry, dissolution behavior and phase transition is critical to elucidate oilfield DTPMP return data and more importantly, can optimize the oilfield scale squeeze design to achieve an extended squeeze lifetime.

  16. The CYP3A4 inhibitor intraconazole does not affect the pharmacokinetics of a new calcium-sensitizing drug levosimendan.

    Science.gov (United States)

    Antila, S; Honkanen, T; Lehtonen, L; Neuvonen, P J

    1998-08-01

    Itraconazole is a potent inhibitor of CYP3A4 isoenzyme and it can cause clinically significant interactions with some other drugs. Levosimendan is a new calcium-sensitizing drug intended for congestive heart failure. We aimed to study possible interactions of itraconazole with levosimendan in healthy volunteers. Twelve healthy male volunteers were included into a randomized, double-blind, two-phase crossover study. A wash-out period of 4 weeks was held between the phases. The subjects were given orally itraconazole 200 mg or placebo daily for 5 days. On the fifth day, they received a single oral dose of 2 mg of levosimendan. Levosimendan plasma concentrations were determined up to 12 hours and ECG, heart rate, and blood pressure followed-up to 8 hours after intake of levosimendan. Itraconazole had no significant effects on the pharmacokinetic parameters of levosimendan. Neither were there any differences in heart rate, PQ-, QTc- or QRS intervals between the placebo and itraconazole phases. The systolic blood pressure was decreased slightly more (p < 0.05) during the itraconazole phase than during the placebo phase. In conclusion, because the potent CYP3A4 inhibitor itraconazole had no significant pharmacokinetic interaction with levosimendan, interactions with CYP3A4 inhibitor, and oral levosimendan are unlikely.

  17. Calcium ionophore (A-23187 induced peritoneal eicosanoid biosynthesis: a rapid method to evaluate inhibitors of arachidonic acid metabolism in vivo

    Directory of Open Access Journals (Sweden)

    T. S. Rao

    1993-01-01

    Full Text Available The present investigation characterizes calcium ionophore (A-23187 induced peritoneal eicosanoid biosynthesis in the rat. Intraperitoneal injection of A-23187 (20 μg/rat stimulated marked biosynthesis of 6-keto-PGF1α (6-KPA, TxB2, LTC4 and LTB4, with no detectable changes on levels of PGE2. Levels of all eicosanoids decreased rapidly after a peak which was seen as early as 5 min. Enzyme markers of cellular contents of neutrophils and mononuclear cells, MPO and NAG respectively, decreased rapidly after ionophore injection; this was followed by increases after 60 min. Indomethacin, a selective cyclooxygenase inhibitor, and zileuton and ICI D-2138, two selective 5-lipoxygenase inhibitors attenuated prostaglandin and leukotriene pathways respectively. Oral administration of zileuton (20 mg/kg, p.o. inhibited LTB4 biosynthesis for up to 6 h suggesting a long duration of pharmacological activity in the rats consistent with its longer half-life. The rapid onset and the magnitude of increases in levels of eicosanoids render the ionophore induced peritoneal eicosanoid biosynthesis a useful model to evaluate pharmacological profiles of inhibitors of eicosanoid pathways in vivo.

  18. A study about some phosphate derivatives as inhibitors of calcium oxalate crystal growth

    Science.gov (United States)

    Grases, F.; March, P.

    1989-08-01

    The kinetic of crystal growth of calcium oxalate monohydrate seed crystals were investigated potentiometrically in the presence of several phosphate derivatives, D-fructose-1,6-diphosphate, pyrophosphate, methylene diphosphonate and phytate, and it was found that in some cases they strongly inhibited crystal growth. The inhibitory action of the different substances assayed was comparatively evaluated.

  19. Content of zinc, iron, calcium and their absorption inhibitors in foods commonly consumed in Ethiopia

    NARCIS (Netherlands)

    Umeta, M.; West, C.E.; Fufa, H.

    2005-01-01

    The zinc, iron, calcium, phosphorus, phytate, tannin and moisture content of 36 foods consumed in rural Ethiopia were analysed. The foods analysed included those based on cereals, starchy tubers and roots, and legumes and vegetables as well as some fruits. Although many foods were relatively rich in

  20. The Effect of a Novel Highly Selective Inhibitor of the Sodium/Calcium Exchanger (NCX) on Cardiac Arrhythmias in In Vitro and In Vivo Experiments

    OpenAIRE

    Kohajda, Zsófia; Farkas-Morvay, Nikolett; Jost, Norbert; Nagy, Norbert; Geramipour, Amir; Horváth, András; Varga, Richárd S.; Hornyik, Tibor; Corici, Claudia; Acsai, Károly; Horváth, Balázs; Prorok, János; Ördög, Balázs; Déri, Szilvia; Tóth, Dániel

    2016-01-01

    Background In this study the effects of a new, highly selective sodium-calcium exchanger (NCX) inhibitor, ORM-10962 were investigated on cardiac NCX current, Ca2+ transients, cell shortening and in experimental arrhythmias. The level of selectivity of the novel inhibitor on several major transmembrane ion currents (L-type Ca2+ current, major repolarizing K+ currents, late Na+ current, Na+/K+ pump current) was also determined. Methods Ion currents in single dog ventricular cells (cardiac myocy...

  1. 外源硝酸钙对水培生菜生长及矿质元素吸收的影响%Effect of Exogenous Calcium Nitrate on Dynamic Growth and Nutrient Absorption of Hydroponic Lettuce

    Institute of Scientific and Technical Information of China (English)

    何鑫; 张存政; 刘贤金; 卢海燕; 梁颖

    2016-01-01

    为有效提高水培生菜产品的营养品质和矿物质含量,试验设置0.1%、0.3%、0.5%3个浓度硝酸钙进行叶面喷施处理,以喷施蒸馏水为对照,对不同处理下生菜生长、产量、品质及矿质元素吸收量进行统计分析.结果表明,硝酸钙叶面喷施处理诱导了SOD、POD、CAT活性的升高.硝酸钙处理28 d,各处理维生素C含量低于对照组,但差异不显著;0.5%处理硝酸盐含量显著高于对照,其他处理与对照组差异不显著;0.3%处理可溶性蛋白、叶绿素含量显著高于对照.外源硝酸钙处理可增加叶片数、根长、根冠比,0.3%处理单株产量升高5.9%,可增加生菜地上部分磷、钾、钙含量,钙元素较对照升高最多,为30.8%,铁升高5.3%,镁下降3.2%.0.1%处理铁、镁含量较对照分别升高30.0%、20.3%.但随着处理浓度的升高镁、铁含量下降,0.5%处理较对照分别下降13.1%、1.1%.随着硝酸钙处理浓度的增加地上部锌逐渐从叶片转移至根,0.5%处理地上部分锌含量最低,为110.1mg· kg-1,较对照下降25.8%.综上,适当浓度的硝酸钙可增加水培生菜钙和部分微量元素含量,增加营养品质,施用过量会影响矿物质元素吸收平衡.本研究结果为指导水培生菜生产过程中应用叶面喷施硝酸钙形成高营养品质,提高微量矿物质元素提供了理论依据.%To determine the mineral content of lettuce under calcium nitrate treatment and improve the nutritional quality of lettuce products,0.1%,0.3%,and 0.5% calcium nitrate was sprayed separately on lettuce foliage and distilled water sprayed as control.The growth index,yield,quality and mineral absorption of lettuce were measured,recorded and statistically analyzed.The results showed that calcium nitrate spraying induced the activities of SOD,POD,and CAT.Calcium nitrate treated 28 days;vitamin C content of 3 treatments was lower than control,but the difference was not

  2. Comparison of efficacy and side effects of combination therapy of angiotensin-converting enzyme inhibitor (benazepril) with calcium antagonist (either nifedipine or amlodipine) versus high-dose calcium antagonist monotherapy for systemic hypertension.

    Science.gov (United States)

    Messerli, F H; Oparil, S; Feng, Z

    2000-12-01

    The present 2 multicenter studies were designed to evaluate whether patients with essential hypertension derived equal benefits from use of combination therapy with a calcium antagonist and angiotensin-converting enzyme (ACE) inhibitor as from doubling the dose of the calcium antagonist. After a 2-week washout and a 2-week single-blind placebo run-in period, a total of 1,390 patients were treated with either nifedipine 30 mg (study 1) or amlodipine 5 mg (study 2) once daily for 4 weeks. The 1,079 patients whose diastolic blood pressure remained between 95 and 115 mm Hg were randomized to 8 weeks of double-blind therapy with amlodipine 5 mg/benazepril 10 mg, amlodipine 5 mg/ benazepril 20 mg, nifedipine 30 mg or nifedipine 60 mg (study 1), and amlodipine 5 mg/benazepril 10 mg, amlodipine 5 mg/benazepril 20 mg, amlodipine 5 mg or amlodipine 10 mg (study 2). Both doses of the calcium antagonist/ACE inhibitor combination therapy lowered diastolic pressure as much as the high dose and significantly better than the lower dose of calcium antagonist monotherapy (with either nifedipine or amlodipine). However, 15% of patients in the nifedipine high-dose monotherapy group and 24% in the amlodipine high-dose monotherapy group presented with some form of edema. In contrast, the incidence of edema was similar for patients treated with both combination therapy and low-dose calcium antagonists. Thus, combination therapy with a calcium antagonist and an ACE inhibitor provides blood pressure control equal to that of high-dose calcium antagonist monotherapy but with significantly fewer dose-dependent adverse experiences such as vasodilatory edema. Inc.

  3. ADVANTAGES OF COMBINATION THERAPY OF HYPERTENSION WITH CALCIUM CHANNEL BLOCKER AND ANGIOTENSIN-CONVERTING ENZYME INHIBITOR IN PATIENTS WITH IMPAIRED RENAL FUNCTION

    Directory of Open Access Journals (Sweden)

    N. A. Dzhaiani

    2014-01-01

    Full Text Available Up-to-date data on combination therapy of arterial hypertension in patients with chronic kidney disease are presented. Special attention is paid to the fixed combination of calcium antagonist lercanidipine and angiotensin-converting enzyme inhibitor enalapril.

  4. Inhibition of calcium carbonate deposition on stainless steel using olive leaf extract as a green inhibitor.

    Science.gov (United States)

    Aidoud, Roumaissa; Kahoul, Abdelkrim; Naamoune, Farid

    2017-01-01

    The antiscale properties of the aqueous extract of olive (Olea europaea L.) leaves as a natural scale inhibitor for stainless steel surface in Hammam raw water were investigated using chronoamperometry (CA) and electrochemical impedance spectroscopy techniques in conjunction with a microscopic examination. The X-ray diffraction analysis reveals that the scale deposited over the pipe walls consists of pure CaCO3 calcite. The CA, in accordance with electrochemical impedance spectra and scanning electron microscopy, shows that the inhibition efficiency increases with increasing extract concentration. This efficiency is considerably reduced as the temperature is increased.

  5. Design, Synthesis and Structure-activity of N-Glycosyl-1-pyridyl-1H-pyrazole-5-carboxamide as Inhibitors of Calcium Channels

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yun-yun; LI Yu-xin; LI Yi-ming; YANG Xiao-ping; MAO Ming-zhen; LI Zheng-ming

    2013-01-01

    Carbohydrates,with broad-spectrum structures and biological functions,are key organic compounds in nature,along with nucleic acids and proteins.As part of our ongoing efforts to develop a new class of pesticides with novel mechanism of action,a series of novel N-glycosyl-l-pyridyl-lH-pyrazole-5-carboxamide was designed and synthesized via the reactions of glycosyl methanamides and pyridyl-pyrazole acid.The compounds were characterized by 1H NMR and 13C NMR.The bioassay results indicate that some of these compounds exhibit moderate insecticidal activities and assessed as potential inhibitors of calcium channels.The modulation of voltage-gated calcium channels by compounds 4a and 5a in the central neurons isolated from the third instar larvae of Spodoptera exigua was studied by whole-cell patch-clamp technique.In addition,compound 5a inhibits the recorded calcium currents reversible on washout.Experimental results also indicate that compound 5a did not release stored calcium from the Endoplasmic Reticulum.The present work demonstrates that N-glycosyl-l-pyridyl-lH-pyrazole-5-carboxamides cannot be used as possible inhibitors of calcium channels for developing novel pesticides.

  6. The effect of cattle slurry in combination with nitrate and the nitrification inhibitor dicyandiamide on in situ nitrous oxide and dinitrogen emissions

    Directory of Open Access Journals (Sweden)

    K. L. McGeough

    2012-07-01

    Full Text Available A field study was conducted to determine the effect of the nitrification inhibitor dicyandiamide (DCD on N2O and N2 emissions after cattle slurry (CS application in the presence of nitrate fertiliser on seven different occasions (between March 2009 and March 2011.

    N2O emissions from CS in the presence of NO3 fertiliser were very high (0.4–8.7% of applied N over a 20 day period, under mild moist conditions. Emissions were significantly larger from the CS treatment compared to an NH4+-N source, supplying the same rate of N as in the slurry. This study supports the view that organic fertilisers should not be applied at the same time as nitrate based fertilisers, as significant increases in N2O emissions occur. The average N2O mole fraction (N2O/(N2O = N2 over all seven application dates was 0.34 for CSNO3 compared to 0.24 for the NH4ClNO3 treatment, indicating the dominance of N2 emissions.

    The rate of nitrification in CSNO3 was slower than in NH4ClNO3 and DCD was found to be an effective nitrification inhibitor in both treatments. However, as N2O emissions were found to be predominantly associated with the NO3 pool, the effect of DCD in lowering N2O emissions is limited in the presence of a NO3 fertiliser. To obtain the maximum cost-benefit of DCD in lowering N2O emissions, under mild moist conditions, its application should be restricted to ammonium based organic or synthetic fertilisers.

  7. ω-Tbo-IT1-New Inhibitor of Insect Calcium Channels Isolated from Spider Venom.

    Science.gov (United States)

    Mikov, Alexander N; Fedorova, Irina M; Potapieva, Natalia N; Maleeva, Ekaterina E; Andreev, Yaroslav A; Zaitsev, Alexey V; Kim, Kira K; Bocharov, Eduard V; Bozin, Timur N; Altukhov, Dmitry A; Lipkin, Alexey V; Kozlov, Sergey A; Tikhonov, Denis B; Grishin, Eugene V

    2015-11-27

    Novel disulfide-containing polypeptide toxin was discovered in the venom of the Tibellus oblongus spider. We report on isolation, spatial structure determination and electrophysiological characterization of this 41-residue toxin, called ω-Tbo-IT1. It has an insect-toxic effect with LD50 19 μg/g in experiments on house fly Musca domestica larvae and with LD50 20 μg/g on juvenile Gromphadorhina portentosa cockroaches. Electrophysiological experiments revealed a reversible inhibition of evoked excitatory postsynaptic currents in blow fly Calliphora vicina neuromuscular junctions, while parameters of spontaneous ones were not affected. The inhibition was concentration dependent, with IC50 value 40 ± 10 nM and Hill coefficient 3.4 ± 0.3. The toxin did not affect frog neuromuscular junctions or glutamatergic and GABAergic transmission in rat brains. Ca(2+) currents in Calliphora vicina muscle were not inhibited, whereas in Periplaneta americana cockroach neurons at least one type of voltage gated Ca(2+) current was inhibited by ω-Tbo-IT1. Thus, the toxin apparently acts as an inhibitor of presynaptic insect Ca(2+) channels. Spatial structure analysis of the recombinant ω-Tbo-IT1 by NMR spectroscopy in aqueous solution revealed that the toxin comprises the conventional ICK fold containing an extended β-hairpin loop and short β-hairpin loop which are capable of making "scissors-like mutual motions".

  8. Renal hemodynamics in hypertensive renal allograft recipients: effects of calcium antagonists and ACE inhibitors.

    Science.gov (United States)

    Grekas, D; Dioudis, C; Kalevrosoglou, I; Alivanis, P; Derveniotis, V; Tourkantonis, A

    1996-06-01

    Hypertension present in more than 50% of successfully renal transplanted patients and its prevalence has slightly increased since the introduction of cyclosporine A. Twenty patients, 9 women and 11 men aged from 30 to 58 years, with stable cadaveric renal allograft function and moderate to severe hypertension, were included in the study. Renal artery graft stenosis causing hypertension were excluded. All patients were given triple drug immunosuppressive treatment with methylprednisolone, azathioprine and cyclosporine A (CsA) and their hypertension was treated with a nifedipine dose of 20 mg twice daily. To evaluate the effect of ACE inhibitors on renal hemodynamics and hypertension, a 4 mg/daily dose of perindopril was added to the above regimen for two months. Effective renal plasma flow (ERPF) decreased from 208 +/- 54 to 168 +/- 61 ml/min and renal vascular resistance (RVR) increased from 75 +/- 12 to 88 +/- 17 mm Hg/ml/min (P nifedipine. It is suggested that the combination of both antihypertensive agents was more effective than monotherapy with nifedipine in controlling blood pressure, but less favorable on the renal hemodynamic response in hypertensive renal transplant patients who were maintained on CsA.

  9. Long-term mTOR inhibitors administration evokes altered calcium homeostasis and platelet dysfunction in kidney transplant patients

    Science.gov (United States)

    López, Esther; Berna-Erro, Alejandro; Bermejo, Nuria; Brull, José María; Martinez, Rocío; Garcia Pino, Guadalupe; Alvarado, Raul; Salido, Ginés María; Rosado, Juan Antonio; Cubero, Juan José; Redondo, Pedro Cosme

    2013-01-01

    The use of the mammal target of rapamycin (mTOR) inhibitors has been consolidated as the therapy of election for preventing graft rejection in kidney transplant patients, despite their immunosuppressive activity is less strong than anti-calcineurin agents like tacrolimus and cyclosporine A. Furthermore, as mTOR is widely expressed, rapamycin (a macrolide antibiotic produced by Streptomyces hygroscopicus) is recommended in patients presenting neoplasia due to its antiproliferative actions. Hence, we have investigated whether rapamycin presents side effects in the physiology of other cell types different from leucocytes, such as platelets. Blood samples were drawn from healthy volunteers and kidney transplant patients long-term medicated with rapamycin: sirolimus and everolimus. Platelets were either loaded with fura-2 or directly stimulated, and immunoassayed or fixed with Laemmli's buffer to perform the subsequent analysis of platelet physiology. Our results indicate that rapamycin evokes a biphasic time-dependent alteration in calcium homeostasis and function in platelets from kidney transplant patients under rapamycin regime, as demonstrated by the reduction in granule secretion observed and subsequent impairment of platelet aggregation in these patients compared with healthy volunteers. Platelet count was also reduced in these patients, thus 41% of patients presented thrombocytopenia. All together our results show that long-term administration of rapamycin to kidney transplant patients evokes alteration in platelet function. PMID:23577651

  10. Effects of the methane-inhibitors nitrate, nitroethane, lauric acid, Lauricidin and the Hawaiian marine algae Chaetoceros on ruminal fermentation in vitro.

    Science.gov (United States)

    Bozic, A K; Anderson, R C; Carstens, G E; Ricke, S C; Callaway, T R; Yokoyama, M T; Wang, J K; Nisbet, D J

    2009-09-01

    The effects of several methane-inhibitors on rumen fermentation were compared during three 24h consecutive batch cultures of ruminal microbes in the presence of nonlimiting amounts of hydrogen. After the initial incubation series, methane production was reduced greater than 92% from that of non-treated controls (25.8+/-8.1 micromol ml(-1) incubation fluid) in cultures treated with nitroethane, sodium laurate, Lauricidin or a finely-ground product of the marine algae, Chaetoceros (added at 1, 5, 5 and 10 mg ml(-1), respectively) but not in cultures treated with sodium nitrate (1 mg m1(-1)). Methane production during two successive incubations was reduced greater than 98% from controls (22.5+/-3.2 and 23.5+/-7.9 micromol ml(-1), respectively) by all treatments. Reductions in amounts of volatile fatty acids and ammonia produced and amounts of hexose fermented, when observed, were most severe in sodium laurate-treated cultures. These results demonstrate that all tested compounds inhibited ruminal methane production in our in vitro system but their effects on fermentation differed.

  11. Attenuation of endothelin-1-induced calcium response by tyrosine kinase inhibitors in vascular smooth muscle cells.

    Science.gov (United States)

    Liu, C Y; Sturek, M

    1996-06-01

    Although tyrosine kinases play an important role in cell growth and have been implicated in regulation of smooth muscle contraction, their role in agonist-induced myoplasmic Ca2+ responses is unclear. We examined effects of the tyrosine kinase inhibitors genistein and methyl 2,5-dihydroxycinnamate (MDHC) on the endothelin-1 (ET-1)-induced Ca2+ response and determined underlying mechanisms for the effects. Freshly isolated smooth muscle cells from porcine coronary arteries were loaded with fura 2 ester, and myoplasmic free Ca2+ (Ca2+ (m)) concentration was estimated with fura 2 microfluorometry. Both genistein and MDHC inhibited the initial transient Cam2+ response to ET by 54 and 81%, respectively (P latent period from ET-1 application to the beginning of the Cam2+ response being increased from 1.08 +/- 0.17 to 2.65 +/- 0.52 min (P < 0.05). In the absence of extracellular Ca2+, genistein inhibited the ET-1-induced Cam2+ response by 93% (P < 0.05). The Cam2+ responses to caffeine (5 mM) or inositol trisphosphate (IP3) applied intracellularly via a patch-clamp pipette were not affected by genistein. Both genistein and MDHC also abolished the sustained Cam2+ response to ET-1. However, the Cam2+ response to depolarization by 80 mM K+ was not inhibited by MDHC and only inhibited 22% by genistein (P < 0.05). These results indicate that 1) activation of tyrosine kinases is an important regulatory mechanism for the ET-1-induced Cam2+ response in vascular smooth muscle and 2) tyrosine kinases mediate ET-1-induced Ca2+ release with no direct effect on IP3-mediated Ca2+ release. Thus ET-1-mediated signaling upstream of IP3 interaction with the Ca2+ stores is regulated by tyrosine kinases.

  12. Role of prefrontal cortical calcium-independent phospholipase A2 in antinociceptive effect of the norepinephrine reuptake inhibitor antidepresssant maprotiline.

    Science.gov (United States)

    Chew, Wee-Siong; Shalini, Suku-Maran; Torta, Federico; Wenk, Markus R; Stohler, Christian; Yeo, Jin-Fei; Herr, Deron R; Ong, Wei-Yi

    2017-01-06

    The prefrontal cortex is essential for executive functions such as decision-making and planning. There is also accumulating evidence that it is important for the modulation of pain. In this study, we investigated a possible role of prefrontal cortical calcium-independent phospholipase A2 (iPLA2) in antinociception induced by the norepinephrine reuptake inhibitor (NRI) and tetracyclic (tricyclic) antidepressant, maprotiline. Intraperitoneal injections of maprotiline increased iPLA2 mRNA and protein expression in the prefrontal cortex. This treatment also reduced grooming responses to von-Frey hair stimulation of the face after facial carrageenan injection, indicating decreased sensitivity to pain. The antinociceptive effect of maprotiline was abrogated by iPLA2 antisense oligonucleotide injection to the prefrontal cortex, indicating a role of this enzyme in antinociception. In contrast, injection of iPLA2 antisense oligonucleotide to the somatosensory cortex did not reduce the antinociceptive effect of maprotiline. Lipidomic analysis of the prefrontal cortex showed decrease in phosphatidylcholine species, but increase in lysophosphatidylcholine species, indicating increased PLA2 activity, and release of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) after maprotiline treatment. Differences in sphingomyelin/ceramide were also detected. These changes were not observed in maprotiline-treated mice that received iPLA2 antisense oligonucleotide to the prefrontal cortex. Metabolites of DHA and EPA may help to strengthen a known supraspinal antinociceptive pathway from the prefrontal cortex to the periaqueductal gray. Together, results indicate a role of prefrontal cortical iPLA2 and its enzymatic products in the antinociceptive effect of maprotiline.

  13. Evaluation of sulfated polysaccharides from the brown seaweed Dictyopteris justii as antioxidant agents and as inhibitors of the formation of calcium oxalate crystals.

    Science.gov (United States)

    Melo, Karoline Rachel Teodosio; Camara, Rafael Barros Gomes; Queiroz, Moacir Fernandes; Vidal, Arthur Anthunes Jacome; Lima, Camila Renata Machado; Melo-Silveira, Raniere Fagundes; Almeida-Lima, Jailma; Rocha, Hugo Alexandre Oliveira

    2013-11-25

    Oxalate crystals and other types of crystals are the cause of urolithiasis, and these are related to oxidative stress. The search for new compounds with antioxidant qualities and inhibitors of these crystal formations is therefore necessary. In this study, we extracted four sulfated polysaccharides, a fucoglucoxyloglucuronan (DJ-0.3v), a heterofucan (DJ-0.4v), and two glucans (DJ-0.5v and DJ-1.2v), from the marine alga Dictyopteris justii. The presence of sulfated polysaccharides was confirmed by chemical analysis and FT-IR. All the sulfated polysaccharides presented antioxidant activity under different conditions in some of the in vitro tests and inhibited the formation of calcium oxalate crystals. Fucan DJ-0.4v was the polysaccharide that showed the best antioxidant activity and was one of the best inhibitors of the crystallization of calcium oxalate. Glucan DJ-0.5v was the second most potent inhibitor of the formation of oxalate crystals, as it stabilized dehydrated oxalate crystals (less aggressive form), preventing them from transforming into monohydrate crystals (more aggressive form). The obtained data lead us to propose that these sulfated polysaccharides are promising agents for use in the treatment of urolithiasis.

  14. Evaluation of Sulfated Polysaccharides from the Brown Seaweed Dictyopteris Justii as Antioxidant Agents and as Inhibitors of the Formation of Calcium Oxalate Crystals

    Directory of Open Access Journals (Sweden)

    Karoline Rachel Teodosio Melo

    2013-11-01

    Full Text Available Oxalate crystals and other types of crystals are the cause of urolithiasis, and these are related to oxidative stress. The search for new compounds with antioxidant qualities and inhibitors of these crystal formations is therefore necessary. In this study, we extracted four sulfated polysaccharides, a fucoglucoxyloglucuronan (DJ-0.3v, a heterofucan (DJ-0.4v, and two glucans (DJ-0.5v and DJ-1.2v, from the marine alga Dictyopteris justii. The presence of sulfated polysaccharides was confirmed by chemical analysis and FT-IR. All the sulfated polysaccharides presented antioxidant activity under different conditions in some of the in vitro tests and inhibited the formation of calcium oxalate crystals. Fucan DJ-0.4v was the polysaccharide that showed the best antioxidant activity and was one of the best inhibitors of the crystallization of calcium oxalate. Glucan DJ-0.5v was the second most potent inhibitor of the formation of oxalate crystals, as it stabilized dehydrated oxalate crystals (less aggressive form, preventing them from transforming into monohydrate crystals (more aggressive form. The obtained data lead us to propose that these sulfated polysaccharides are promising agents for use in the treatment of urolithiasis.

  15. Waterproofing Materials for Ammonium Nitrate

    Directory of Open Access Journals (Sweden)

    R.S. Damse

    2004-10-01

    Full Text Available This study explores the possibility of overcoming the problem of hygroscopicity of ammonium nitrate by coating the particles with selected waterproofing materials. Gravimetric analysis ofthe samples of ammonium nitrate coated with eight different waterproofing materials, vis-a-vis, uncoated ammonium nitrate, were conducted at different relative humidity and exposuretime. The results indicate that mineral jelly is the promising waterproofing material for ammonium nitrate among the materials tested, viz, calcium stearate, dioctyl phthalate, kaoline, diethylphthalate, dinitrotoluene, shelac varnish, and beeswax. Attempts were made to confirm the waterproofing ability of mineral jelly to ammonium nitrate using differential thermal analysisand x-ray diffraction patterns as an experimental tool. Suitability of mineral jelly as an additive for the gun propellant was also assessed on the basis of theoretical calculations using THERMprogram.

  16. Effects of Nitrogen Fertilizer with Nitrification Inhibitor DMPP (3,4-Dimethylpyrazole phosphate) on Nitrate Accumulation and Quality ofCabbage (Brassica campastris L. ssp. pekinesis)

    Institute of Scientific and Technical Information of China (English)

    XUChao; WULiang-huan; JUXiao-tang; ZHANGFu-suo

    2004-01-01

    To assess the effects of N fertilizer ammonium sulphate nitrate [ (NH4)2SO4 plus NH4NO3;ASN] with the new nitrification inhibitor (NI) 3, 4-dimethylpyrazole phosphate (DMPP) (ASN+DMPP) on yield, nitrate accumulation, and quality of cabbage (Brassica campastris L. ssp. pekinesis), two field trials were carried out under various soil-climatic conditions in Jinhua City and Xinchang County, Zhejiang Province of China in 2002.Results showed that DMPP could increase the mean yield by + 2.0 t ha-1 in Jinhua, +5.5 t ha-1 in Xinchang, decrease NO3--N content by -9.4% in Jinhua, -7.3% in Xinchang and improve nutritional quality by increasing vitamin C (VC), soluble sugar, K, Fe, Zn contents significantly.

  17. Calcium channel blockers, angiotensin receptor blockers, and angiotensin-converting enzyme inhibitors: Effectiveness in combination with diuretics or β-blockers for treating hypertension

    Science.gov (United States)

    Bisognano, John D; McLaughlin, Trent; Roberts, Craig S; Tang, Simon SK

    2007-01-01

    This retrospective database analysis compared the effectiveness of dihydropyridine calcium channel blockers (DHPs), angiotensin-converting enzyme (ACE) inhibitors, and angiotensin receptor blockers (ARBs) added to diuretics or β-blockers. Adults with hypertension treated with diuretic or β-blocker monotherapy between 1998 and 2001 were identified from a large US electronic medical records database of primary care practices. Patients were required to have a baseline blood pressure (BP) ≥140/90 mmHg (≥130/80 mmHg for diabetes mellitus) and recorded BP measurements within 6 months before and 1–12 months following index date. Patients were matched 1:1:1 by propensity score to correct for differences in baseline characteristics. 1875 patients met study criteria and 660 (220 in each cohort) were matched based on propensity scores. Matched cohorts had no significant differences in baseline characteristics. Mean changes in systolic/diastolic BP were −17.5/−8.8, −15.7/−6.3, and −13.0/−8.0 mmHg with DHPs, ACE inhibitors, and ARBs, respectively. Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High BP 6/7 goal attainment for each regimen was 47.3%, 40.0%, and 32.2%, respectively. DHPs, ACE inhibitors, and ARBs improved BP when added to patients’ β-blocker or diuretic therapy. The greatest benefits were observed with DHPs, followed by ACE inhibitors, then ARBs. PMID:18078009

  18. Calcium - Function and effects

    NARCIS (Netherlands)

    Liang, Jianfen; He, Yifan; Gao, Qian; Wang, Xuan; Nout, M.J.R.

    2016-01-01

    Rice is the primary food source for more than half of the world population. Levels of calcium contents and inhibitor - phytic acid are summarized in this chapter. Phytic acid has a very strong chelating ability and it is the main inhibit factor for calcium in rice products. Calcium contents in br

  19. Calcium phosphate-polymer hybrid nanoparticles for enhanced triple negative breast cancer treatment via co-delivery of paclitaxel and miR-221/222 inhibitors.

    Science.gov (United States)

    Zhou, Zilan; Kennell, Carly; Lee, Joo-Youp; Leung, Yuet-Kin; Tarapore, Pheruza

    2017-02-01

    In this study, a development of a novel calcium phosphate-polymer hybrid nanoparticle system is reported.The nanoparticle system can co-encapsulate and co-deliver a combination of therapeutic agents with different physicochemical properties (i.e., inhibitors for microRNA-221 and microRNA-222 (miRi-221/222) and paclitaxel (pac)).miRi-221/222 are hydrophilic and were encapsulated with calcium phosphate by co-precipitation in a water-in-oil emulsion.The precipitates were then coated with an anionic lipid, dioleoylphosphatidic acid (DOPA), to co-encapsulate hydrophobic paclitaxel outside the hydrophilic precipitates and inside the same nanoparticle.The nanoparticles formed by following this approach had a size of about ≤100nm and contained both lipid-coated calcium phosphate/miRi and paclitaxel.This nanoparticle system was found to simultaneously deliver paclitaxel and miRi-221/222 to their intracellular targets, leading to inhibit proliferative mechanisms of miR-221/222 and thus significantly enhancing the therapeutic efficacy of paclitaxel.

  20. 外源钙及钙抑制剂对番茄耐弱光特性的调控作用%Regulations of Calcium and Calcium Inhibitors on the Low Light Tolerance in Tomato

    Institute of Scientific and Technical Information of China (English)

    李益清; 李天来

    2011-01-01

    In order to investigate the regulating mechanism of calcium on tomato low light tolerance, one tomato(Lycopersicon esculentum Mill) strain W were used to study the changes of plant height, stem diameter, photosynthesis and protective enzymes activities, after the tomato were treated by calcium, calcium channel inhibitor LaCl3 and Ca2+ chelator (EGTA) under the 50% nature light intensity. The results showed that Caz+ treatment could inhibit the phenomenon of spindly growth which was caused by low light stress to a certain extent, decrease MDA content, increase the activities of SOD, CAT, and POD, promote the content of soluble protein in the leaves of tomato under low light stress (475. 2 - 616. 5 μmol · m-2 · s-1) which is covered 50% nature light, close to or even reach the control level under 100% nature light intensity. But the effects of calcium channel inhibitor and Ca2+ chelator were opposite. These results indicated that the effects of calcium on the growth and development of plant, photosynthesis, activities of protective enzymes and the content of soluble protein in the leaves of tomato under low light stress was a positive regulation, this maybe one of the important reasons for that calcium could increased low light tolerance of tomato, prevented low light damage to the plant in a certain extent.%为探讨外源钙对番茄弱光胁迫生育障碍的可能调控作用,以栽培型番茄(L ycopersicon esculentum Mill)品系W为材料,采用外源钙和钙通道抑制剂LaCl3及钙离子螯合剂EGTA处理50%自然光强(实测光通量密度为475.2~616.5 μmol·m-2·s-1)条件下生长的番茄植株,通过各项相关指标的测定研究其对弱光下番茄生长发育、光合作用、防御酶活性等的影响.结果表明,遮光50%的弱光条件下,27 mmol·L-1CaCl2处理的番茄茎粗增加,植株整体生长健壮,有效抑制植株徒长.外源钙可通过有效防护胁迫所致的氧化损伤,维持较高的防御酶活性及可溶

  1. Calcium channel blockers, angiotensin receptor blockers, and angiotensin-converting enzyme inhibitors: Effectiveness in combination with diuretics or β-blockers for treating hypertension

    Directory of Open Access Journals (Sweden)

    John D Bisognano

    2007-11-01

    Full Text Available John D Bisognano1, Trent McLaughlin2, Craig S Roberts3, Simon SK Tang31Internal Medicine Department, Cardiology Division, the University of Rochester Medical Center, Rochester, NY, USA; 2NDC Health, Phoenix, Arizona, USA; 3Pfizer Inc, New York, NY, USAAbstract: This retrospective database analysis compared the effectiveness of dihydropyridine calcium channel blockers (DHPs, angiotensin-converting enzyme (ACE inhibitors, and angiotensin receptor blockers (ARBs added to diuretics or β-blockers. Adults with hypertension treated with diuretic or β-blocker monotherapy between 1998 and 2001 were identified from a large US electronic medical records database of primary care practices. Patients were required to have a baseline blood pressure (BP ≥140/90 mmHg (≥130/80 mmHg for diabetes mellitus and recorded BP measurements within 6 months before and 1–12 months following index date. Patients were matched 1:1:1 by propensity score to correct for differences in baseline characteristics. 1875 patients met study criteria and 660 (220 in each cohort were matched based on propensity scores. Matched cohorts had no significant differences in baseline characteristics. Mean changes in systolic/diastolic BP were –17.5/–8.8, –15.7/–6.3, and –13.0/–8.0 mmHg with DHPs, ACE inhibitors, and ARBs, respectively. Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of High BP 6/7 goal attainment for each regimen was 47.3%, 40.0%, and 32.2%, respectively. DHPs, ACE inhibitors, and ARBs improved BP when added to patients’ β-blocker or diuretic therapy. The greatest benefits were observed with DHPs, followed by ACE inhibitors, then ARBs.Keywords: hypertension, amlodipine besylate, lisinopril, valsartan, Joint National Committee (JNC 6 and 7

  2. [Response of N transformation related soil enzyme activities to inhibitor applications].

    Science.gov (United States)

    Chen, Lijun; Wu, Zhijie; Jiang, Yong; Zhou, Likai

    2002-09-01

    With an aerobic incubation test, this paper studied the response of soil urease, nitrate reductase, nitrite reductase, and hydroxylamine reductase to urease inhibitor hydroquinone (HQ) applied in combination with nitrification inhibitor encapsulated calcium carbide (HQ + ECC) or dicyandiamide (HQ + DCD). The results showed that HQ + DCD could inhibit urease activity and increase activities of nitrate reductase, nitrite reductase, and hydroxylamine reductase significantly in comparison with CK, HQ and HQ + ECC. Under the condition of our test, there existed a significant relationship between soil urease, nitrate reductase, nitrite reductase, and hydroxylamine reductase activities and soil NH4+ and NO3- contents, NH3 volatilization and N2O emission rate, and regression analysis indicated that there were significantly positive relationships between soil urease, nitrite reductase and hydroxylamine reductase activities.

  3. Accelerated corrosion testing results for specimens containing uncoated reinforcing steel and corrosion inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Kondratova, I. L.; Montes, P.; Bremner, T. W. [New Brunswick Univ., Dept, of Civil Engineering, Fredericton, NB (Canada)

    2000-07-01

    Concrete mixtures (water-cement ratios of 0.25, 0.40. or 0.60) containing uncoated reinforcing bars with a simulated crack, formed transverse to the axis of the bar, and with three commercial corrosion inhibitors added for corrosion protection (organic corrosion inhibitor,calcium nitrate-based corrosion inhibitor, and migratory corrosion inhibitor), were tested for corrosion damage. The objective was to evaluate the effectiveness of the different corrosion inhibitors in uncracked and cracked concrete slabs in a simulated marine environment. The specimens were placed in an accelerated exposure cabinet with four cycles of wetting and drying per day in simulated seawater, and corrosion rates measured using the linear polarization technique. Water-soluble chloride content in the rebars was analyzed at the end of the exposure period. The three corrosion inhibitors were found to show a wide variation in performance. There was a direct correlation between their effectiveness and addition rate. All three appeared to be more effective in reducing corrosion rate in a higher water-to-cement ratio concrete. Consistent performance was provided only by calcium nitrate at an addition rate of 25 litre/cu m of concrete, with water-to-cement ratios of 0.60 and 0.40. Pitting corrosion was observed in all pre-cracked high performance concrete specimens; the depth of the pit tended to be deeper when a corrosion inhibitor was used. 6 refs., 6 tabs., 6 figs.

  4. Profitability of Nitrification Inhibitors for Abatement of Nitrate Leaching on a Representative Dairy Farm in the Waikato Region of New Zealand

    Directory of Open Access Journals (Sweden)

    Upa H. Paragahawewa

    2011-11-01

    Full Text Available Direct policies for the management of nonpoint source pollution are difficult to apply given asymmetric information, spatial and temporal variability, and uncertainty. There is increasing awareness that these limitations may be overcome where profitable mitigation practices are broadly adopted by polluters. Nitrification inhibitors (chemicals applied to paddocks that retard the nitrification process in soils are a rare example of a mitigation practice that reduces pollutant loads and potentially increases farm profit through promoting pasture production. This study investigates their capacity to achieve both goals to inform policy makers and producers of their potential for simultaneously improving farm profit and water quality. With an assumed 10 percent increase in pasture production in response to nitrification inhibitor application, nitrification inhibitors are a profitable innovation because greater pasture production supports higher stocking rates. Nonetheless, their overall impact on farm profit is low, even when the cost of inhibitors or their impact on subsequent pasture production is substantially altered. However, inhibitors are found to be a critical mitigation practice for farmers posed with decreasing leaching loads to satisfy regulatory requirements. These findings suggest that, despite their shortcomings for nonpoint pollution regulation, direct policies appear to be the only way to motivate producers to account for their impact on environmental values given the current lack of profitable mitigations.

  5. Insensitive Ammonium Nitrate.

    Science.gov (United States)

    is reduced by replacing the ammonium nitrate with a solid solution of potassium nitrate in form III ammonium nitrate wherein the potassium nitrate...constitutes from more than zero to less than 50 weight percent of the solid solution . (Author)

  6. Beta-blocker, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker, nitrate-hydralazine, diuretics, aldosterone antagonist, ivabradine, devices and digoxin (BANDAID(2) ): an evidence-based mnemonic for the treatment of systolic heart failure.

    Science.gov (United States)

    Chia, N; Fulcher, J; Keech, A

    2016-06-01

    Heart failure causes significant morbidity and mortality, with recognised underutilisation rates of guideline-based therapies. Our aim was to review current evidence for heart failure treatments and derive a mnemonic summarising best practice, which might assist physicians in patient care. Treatments were identified for review from multinational society guidelines and recent randomised trials, with a primary aim of examining their effects in systolic heart failure patients on mortality, hospitalisation rates and symptoms. Secondary aims were to consider other clinical benefits. MEDLINE and EMBASE were searched using a structured keyword strategy and the retrieved articles were evaluated methodically to produce an optimised reference list for each treatment. We devised the mnemonic BANDAID (2) , standing for beta-blocker, angiotensin-converting enzyme inhibitor/angiotensin receptor blocker, nitrate-hydralazine (or potentially neprilysin inhibitor), diuretics, aldosterone antagonist, ivabradine, devices (automatic implantable cardioverter defibrillator, cardiac resynchronisation therapy or both) and digoxin as a representation of treatments with strong evidence for their use in systolic heart failure. Treatment with omega-3 fatty acids, statins or anti-thrombotic therapies has limited benefits in a general heart failure population. Adoption of this mnemonic for current evidence-based treatments for heart failure may help improve prescribing rates and patient outcomes in this debilitating, high mortality condition.

  7. Biodegradation of Glycidol and Glycidyl Nitrate

    OpenAIRE

    1982-01-01

    When calcium hydroxide is used to desensitize glycerol trinitrate (nitroglycerine)-containing waste streams, the epoxides glycidol and glycidyl nitrate are formed. The epoxide rings of both compounds are unstable to heat in aqueous solutions, and they open to form glycerol 1-mononitrate and presumably glycerol. These transformations were accelerated by microbial activity. Glycerol 1-mononitrate was slowly denitrated to form glycerol. Glycidol and glycidyl nitrate caused base-pair substitution...

  8. Synthesis and evaluation of calcium sulfate scale inhibitor%硫酸钙阻垢剂(MAM)的合成与评价

    Institute of Scientific and Technical Information of China (English)

    李建波; 李永会; 钟小芳

    2013-01-01

    以马来酸为主要单体合成了一种四元共聚物阻垢剂(MAM),用正交实验进行了合成条件的优化研究,确定了最优的合成条件:m(马来酸):m (AA):m (AMPS):m(AM)=5∶5∶4∶0.5,引发剂与单体的质量比为8%,4种单体的总质量分数为15%,反应温度为90℃,反应时间为4h.研究了阻垢剂用量、溶液pH、钙离子浓度、硫酸根离子浓度、温度、恒温时间对该共聚物阻垢剂阻硫酸钙垢性能的影响,结果表明,在温度为70℃、溶液pH=7、ρ (Ca2+)=4 000 mg/L、ρ(SO42-)=7 000 mg/L、ρ(NaCl)=7.5 g/L的条件下,当MAM投加量为3 mg/L、恒温时间为25 h时,阻垢率为98.58%.%The quadripolymer scale inhibitor (MAM) has been synthesized with maleic acid as main monomer. The synthetic conditions are optimized by orthogonal tests. The result proves that the optimum synthetic conditions of the quadripolymer are as follows:m(MA):m(AA):m(AMPS):m(AM)=5:5:4:0.5,m[(NH4)2S2O8]:m(MA+AA+AMPS+ AM)=8%,m(MA+AA+AMPS+AM):m(MA+AA+AMPS+AM+H2O)=15%,reaction temperature at 90 ℃,and reaction time 4 h. The effects of scale inhibitor dosage, Ph of the solution, calcium ion concentration, sulfate ion concentration , solution temperature and constant temperature time on the inhibition efficiency of calcium sulfate scale are evaluated. The result proves that the scale-inhibiting rate will be 98.58%,when the temperature is 70 ℃ ,ρ(Ca2+) = 4 000 mg/L,ρ(SO42-) = 7 000 mg/L,ρ(NaCl)=7.5 g/L,and solution Ph=7 ,and when the dosage of MAM is 3 mg/L, and constant temperature time is 25 h.

  9. Effects of Small Molecule Calcium-Activated Chloride Channel Inhibitors on Structure and Function of Accessory Cholera Enterotoxin (Ace of Vibrio cholerae.

    Directory of Open Access Journals (Sweden)

    Tanaya Chatterjee

    Full Text Available Cholera pathogenesis occurs due to synergistic pro-secretory effects of several toxins, such as cholera toxin (CTX and Accessory cholera enterotoxin (Ace secreted by Vibrio cholerae strains. Ace activates chloride channels stimulating chloride/bicarbonate transport that augments fluid secretion resulting in diarrhea. These channels have been targeted for drug development. However, lesser attention has been paid to the interaction of chloride channel modulators with bacterial toxins. Here we report the modulation of the structure/function of recombinant Ace by small molecule calcium-activated chloride channel (CaCC inhibitors, namely CaCCinh-A01, digallic acid (DGA and tannic acid. Biophysical studies indicate that the unfolding (induced by urea free energy increases upon binding CaCCinh-A01 and DGA, compared to native Ace, whereas binding of tannic acid destabilizes the protein. Far-UV CD experiments revealed that the α-helical content of Ace-CaCCinh-A01 and Ace-DGA complexes increased relative to Ace. In contrast, binding to tannic acid had the opposite effect, indicating the loss of protein secondary structure. The modulation of Ace structure induced by CaCC inhibitors was also analyzed using docking and molecular dynamics (MD simulation. Functional studies, performed using mouse ileal loops and Ussing chamber experiments, corroborate biophysical data, all pointing to the fact that tannic acid destabilizes Ace, inhibiting its function, whereas DGA stabilizes the toxin with enhanced fluid accumulation in mouse ileal loop. The efficacy of tannic acid in mouse model suggests that the targeted modulation of Ace structure may be of therapeutic benefit for gastrointestinal disorders.

  10. Effects of Small Molecule Calcium-Activated Chloride Channel Inhibitors on Structure and Function of Accessory Cholera Enterotoxin (Ace) of Vibrio cholerae

    Science.gov (United States)

    Chatterjee, Tanaya; Sheikh, Irshad Ali; Chakravarty, Devlina; Chakrabarti, Pinak; Sarkar, Paramita; Saha, Tultul; Chakrabarti, Manoj K.; Hoque, Kazi Mirajul

    2015-01-01

    Cholera pathogenesis occurs due to synergistic pro-secretory effects of several toxins, such as cholera toxin (CTX) and Accessory cholera enterotoxin (Ace) secreted by Vibrio cholerae strains. Ace activates chloride channels stimulating chloride/bicarbonate transport that augments fluid secretion resulting in diarrhea. These channels have been targeted for drug development. However, lesser attention has been paid to the interaction of chloride channel modulators with bacterial toxins. Here we report the modulation of the structure/function of recombinant Ace by small molecule calcium-activated chloride channel (CaCC) inhibitors, namely CaCCinh-A01, digallic acid (DGA) and tannic acid. Biophysical studies indicate that the unfolding (induced by urea) free energy increases upon binding CaCCinh-A01 and DGA, compared to native Ace, whereas binding of tannic acid destabilizes the protein. Far-UV CD experiments revealed that the α-helical content of Ace-CaCCinh-A01 and Ace-DGA complexes increased relative to Ace. In contrast, binding to tannic acid had the opposite effect, indicating the loss of protein secondary structure. The modulation of Ace structure induced by CaCC inhibitors was also analyzed using docking and molecular dynamics (MD) simulation. Functional studies, performed using mouse ileal loops and Ussing chamber experiments, corroborate biophysical data, all pointing to the fact that tannic acid destabilizes Ace, inhibiting its function, whereas DGA stabilizes the toxin with enhanced fluid accumulation in mouse ileal loop. The efficacy of tannic acid in mouse model suggests that the targeted modulation of Ace structure may be of therapeutic benefit for gastrointestinal disorders. PMID:26540279

  11. Combination therapy of renin-angiotensin system inhibitors plus calcium channel blockers versus other two-drug combinations for hypertension: a systematic review and meta-analysis.

    Science.gov (United States)

    Lu, Z; Chen, Y; Li, L; Wang, G; Xue, H; Tang, W

    2017-01-01

    Many randomized clinical trials (RCTs) have investigated the efficacy and safety of renin-angiotensin system inhibitors (RASIs) plus calcium channel blockers (CCBs), compared with other two-drug combinations, but systematic assessment in this aspect is still lacking. We carried out the present meta-analysis of randomized controlled trials to evaluate the long-term effect and safety of RASIs plus CCBs. Literatures were searched in MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials in September 2014. A fixed-effect model was used to estimate the pooled effect of trials identified. Thirty-four trials with 41 694 patients were included. Compared with RASIs plus diuretics, RASIs plus CCBs decreased total cardiovascular (CV) events (relative risk (RR) 0.82, 95% confidence interval (CI): 0.75, 0.91, adjusted RR (ARR) 1.7%) and withdrawals due to adverse effect (WDAE) (RR 0.87, 95% CI: 0.80, 0.94, ARR 1.3%). Compared with CCBs plus diuretics, RASIs plus CCBs decreased WDAE (RR 0.63, 95% CI: 0.45, 0.90, ARR 1.1%). Our meta-analysis indicates that RASIs plus CCBs provide a superior safety and prevention of CV events to RASIs plus diuretics, whereas this combination is also safer than CCBs plus diuretics. We also raise a new hypothesis. More high-quality RCTs focused on hard end points with CV, cerebrovascular and renal events are needed to confirm the hypothesis we have brought out.

  12. Efficacy of calcium-EDTA as an inhibitor for metallo-β-lactamase in a mouse model of Pseudomonas aeruginosa pneumonia.

    Science.gov (United States)

    Aoki, Nobumasa; Ishii, Yoshikazu; Tateda, Kazuhiro; Saga, Tomoo; Kimura, Soichiro; Kikuchi, Yoshiaki; Kobayashi, Tetsuo; Tanabe, Yoshinari; Tsukada, Hiroki; Gejyo, Fumitake; Yamaguchi, Keizo

    2010-11-01

    In this study, we have evaluated the efficacy of calcium-EDTA (Ca-EDTA) as an inhibitor of bacterial metalloenzymes, such as metallo-β-lactamase (MBL) and other proteases, in a mouse model of Pseudomonas aeruginosa pneumonia. The simultaneous presence of Ca-EDTA (32 μg/ml) reduced the MICs of imipenem (IPM) in all MBL-producing P. aeruginosa isolates (IMP-1, -2, -7, and -10 and VIM-2) but not non-MBL-producing strains. In the pneumonia model, mice were intranasally infected with MBL-producing P. aeruginosa and then kept under conditions of hyperoxia to mimic ventilator-associated pneumonia. With both intranasal and subcutaneous administrations, Ca-EDTA significantly potentiated survival benefits of IPM compared to those of IPM alone. Ca-EDTA combination therapy induced a significant reduction of the bacterial burden in the lungs (P EDTA against MBL activity was confirmed by using the purified IMP-1 enzyme, which was characterized by a 50% inhibitory concentration (IC(50)) of 55 ± 8.2 μM. Finally, the protective effects of Ca-EDTA were demonstrated by culture supernatant-induced epithelial cell damage and acute lung injury in mice. These data suggest the therapeutic potential of Ca-EDTA not only by the blocking of MBLs but also by neutralizing tissue-damaging metalloproteases in P. aeruginosa infections.

  13. Renoprotective Effect of the Combination of Renin-angiotensin System Inhibitor and Calcium Channel Blocker in Patients with Hypertension and Chronic Kidney Disease

    Institute of Scientific and Technical Information of China (English)

    Rong-Shuang Huang; Yi-Ming Cheng; Xiao-Xi Zeng; Sehee Kim; Ping Fu

    2016-01-01

    Background:Renin-angiotensin system inhibitor and calcium channel blocker (CCB) are widely used in controlling blood pressure (BP) in patients with chronic kidney disease (CKD).We carried out a meta-analysis to compare the renoprotective effect of the combination of angiotensin-converting enzyme inhibitor (ACEI) or angiotensin receptor blocker (ARB) and CCB (i.e.,ACEI/ARB + CCB) with ACEI/ ARB monotherapy in patients with hypertension and CKD.Methods:Publications were identified from PubMed,Embase,Medline,and Cochrane databases.Only randomized controlled trials (RCTs) of BP lowering treatment for patients with hypertension and CKD were considered.The outcomes of end-stage renal disease (ESRD),cardiovascular events,BP,urinary protein measures,estimated glomerular filtration rate (GFR),and adverse events were extracted.Results:Based on seven RCTs with 628 patients,ACEI/ARB + CCB did not show additional benefit for the incidence of ESRD (risk ratio [RR] =0.84;95% confidence interval [CI]:0.52-1.33) and cardiovascular events (RR =0.58;95% CI:0.21-1.63) significantly,compared with ACEI/ARB monotherapy.There were no significant differences in change from baseline to the end points in diastolic BP (weighted mean difference [WMD] =-1.28 mmHg;95% CI:-3.18 to-0.62),proteinuria (standard mean difference =-0.55;95% CI:-1.41 to-0.30),GFR (WMD =-0.32 ml/min;95% CI:-1.53 to-0.89),and occurrence of adverse events (RR =1.05;95% CI:0.72-1.53).However,ACEI/ARB + CCB showed a greater reduction in systolic BP (WMD =-4.46 mmHg;95% CI:-6.95 to-1.97),compared with ACEI/ARB monotherapy.Conclusion:ACEI/ARB + CCB had no additional renoprotective benefit beyond than what could be achieved with ACEI/ARB monotherapy.

  14. Association between calcium sensing receptor gene polymorphisms and chronic pancreatitis in a US population: Role of serine protease inhibitor Kazal 1type and alcohol

    Institute of Scientific and Technical Information of China (English)

    Venkata Muddana; David C Whitcomb; Janette Lamb; Julia B Greer; Beth Elinoff; Robert H Hawes; Peter B cotton; Michelle A Anderson; Randall E Brand; Adam Slivka

    2008-01-01

    AIM: To test the hypothesis that calcium sensing receptor (CASR) polymorphisms are associated with chronic pancreatitis (CP), and to determine whether serine protease inhibitor Kazal 1type (SPfNK1) N34S or alcohol are necessary co-factors in its etiology.METHODS: Initially, 115 subjects with pancreatitis and 66 controls were evaluated, of whom 57 patients and 21 controls were predetermined to carry the high-risk SP/NK1 N34S polymorphism. We sequenced CASR gene exons 2, 3, 4, 5 and 7, areas containing the majority of reported polymorphisms and novel mutations. Based on the initial results, we added 223 patients and 239 controls to analyze three common nonsynonymous single nucleotide polymorphisrns (SNPs) in exon 7 (A986S, R990G, and Q1011E).RESULTS: The CASR exon 7 R990G polymorphism was significantly associated with CP (OR, 2.01; 95% CI, 1.12-3.59; P = 0.015). The association between CASR R990G and CP was stronger in subjects who reported moderate or heavy alcohol consumption (OR,3.12; 95% CI, 1.14-9.13; P = 0.018). There was no association between the various CASR genotypes and SPINK1 N34S in pancreatitis. None of the novel CASR polymorphisms reported from Germany and India was detected.CONCLUSION: Our United States-based study confirmed an association of CASR and CP and for the first time demonstrated that CASR R990G is a significant risk factor for CP. We also conclude that the risk of CP with CASR R990G is increased in subjects with moderate to heavy alcohol consumption.

  15. Viscosity of multi-component molten nitrate salts : liquidus to 200 degrees C.

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, Robert W.

    2010-03-01

    The viscosity of molten salts comprising ternary and quaternary mixtures of the nitrates of sodium, potassium, lithium and calcium was determined experimentally. Viscosity was measured over the temperature range from near the relatively low liquidus temperatures of he individual mixtures to 200C. Molten salt mixtures that do not contain calcium nitrate exhibited relatively low viscosity and an Arrhenius temperature dependence. Molten salt mixtures that contained calcium nitrate were relatively more viscous and viscosity increased as the roportion of calcium nitrate increased. The temperature dependence of viscosity of molten salts containing calcium nitrate displayed curvature, rather than linearity, when plotted in Arrhenius format. Viscosity data for these mixtures were correlated by the Vogel-Fulcher- ammann-Hesse equation.

  16. Synthesis and evaluation of 6-pyrazoylamido-3N-substituted azabicyclo[3,1,0]hexane derivatives as T-type calcium channel inhibitors for treatment of neuropathic pain.

    Science.gov (United States)

    Kim, Jung Hyun; Nam, Ghilsoo

    2016-11-01

    A new series of aryls, including benzo[d]imidazole/isoxazole/pyrazole, conjugated to 3N-substituted-azabicyclo[3.1.0]hexane derivatives were designed and synthesized as inhibitors of T-type calcium channels. Among the synthesized compounds, 3N-R-substituted azabicyclo[3.1.0]hexane carboxamide derivatives containing 5-isobutyl-1-phenyl-pyrazole ring exhibited potent and selective T-channel inhibition and good metabolic stability without CYP450 inhibition. Compounds 10d and 10e contained hydrophobic substituents at the 3N-position and exhibited potent in vitro efficacy, as well as neuropathic pain alleviation in rats.

  17. Organic nitrates and nitrate tolerance--state of the art and future developments.

    Science.gov (United States)

    Daiber, Andreas; Münzel, Thomas; Gori, Tommaso

    2010-01-01

    The hemodynamic and antiischemic effects of nitroglycerin (GTN) are lost upon chronic administration due to the rapid development of nitrate tolerance. The mechanism of this phenomenon has puzzled several generations of scientists, but recent findings have led to novel hypotheses. The formation of reactive oxygen and nitrogen species in the mitochondria and the subsequent inhibition of the nitrate-bioactivating enzyme mitochondrial aldehyde dehydrogenase (ALDH-2) appear to play a central role, at least for GTN, that is, bioactivated by ALDH-2. Importantly, these findings provide the opportunity to reconcile the two "traditional" hypotheses of nitrate tolerance, that is, the one postulating a decreased bioactivation and the concurrent one suggesting a role of oxidative stress. Furthermore, recent animal and human experimental studies suggest that the organic nitrates are not a homogeneous group but demonstrate a broad diversity with regard to induction of vascular dysfunction, oxidative stress, and other side effects. In the past, attempts to avoid nitrate-induced side effects have focused on administration schedules that would allow a "nitrate-free interval"; in the future, the role of co-therapies with antioxidant compounds and of activation of endogeneous protective pathways such as the heme oxygenase 1 (HO-1) will need to be explored. However, the development of new nitrates, for example, tolerance-free aminoalkyl nitrates or combination of nitrate groups with established cardiovascular drugs like ACE inhibitors or AT(1)-receptor blockers (hybrid molecules) may be of great clinical interest.

  18. Biodegradation of Glycidol and Glycidyl Nitrate

    Science.gov (United States)

    Kaplan, David L.; Cornell, John H.; Kaplan, Arthur M.

    1982-01-01

    When calcium hydroxide is used to desensitize glycerol trinitrate (nitroglycerine)-containing waste streams, the epoxides glycidol and glycidyl nitrate are formed. The epoxide rings of both compounds are unstable to heat in aqueous solutions, and they open to form glycerol 1-mononitrate and presumably glycerol. These transformations were accelerated by microbial activity. Glycerol 1-mononitrate was slowly denitrated to form glycerol. Glycidol and glycidyl nitrate caused base-pair substitutions in the Ames test for mutagenicity, whereas glycerol 1-mononitrate tests were negative. PMID:16345917

  19. Biodegradation of glycidol and glycidyl nitrate.

    Science.gov (United States)

    Kaplan, D L; Cornell, J H; Kaplan, A M

    1982-01-01

    When calcium hydroxide is used to desensitize glycerol trinitrate (nitroglycerine)-containing waste streams, the epoxides glycidol and glycidyl nitrate are formed. The epoxide rings of both compounds are unstable to heat in aqueous solutions, and they open to form glycerol 1-mononitrate and presumably glycerol. These transformations were accelerated by microbial activity. Glycerol 1-mononitrate was slowly denitrated to form glycerol. Glycidol and glycidyl nitrate caused base-pair substitutions in the Ames test for mutagenicity, whereas glycerol 1-mononitrate tests were negative.

  20. Modeled Wet Nitrate Deposition

    Data.gov (United States)

    U.S. Environmental Protection Agency — Modeled data on nitrate wet deposition was obtained from Dr. Jeff Grimm at Penn State Univ. Nitrate wet depostion causes acidification and eutrophication of surface...

  1. Micromachined Amperometric Nitrate Sensor

    OpenAIRE

    Dohyun Kim; Ira Goldberg; Jack Judy

    2003-01-01

    A nitrate-sensing system that consists of a micromachined sensor substrate, nitrate-permeable membrane, integrated microfluidic channels, and standard fluidic connectors has been designed, fabricated, assembled, and tested. Our microsensor was designed for in-situ monitoring of nitrate concentrations in ground water. A silver electrode was patterned for amperometric nitrate detection. An electrochemically oxidized silver electrode was used as a reference electrode. Microfluidic channels were ...

  2. 21 CFR 181.33 - Sodium nitrate and potassium nitrate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrate and potassium nitrate. 181.33...-Sanctioned Food Ingredients § 181.33 Sodium nitrate and potassium nitrate. Sodium nitrate and potassium nitrate are subject to prior sanctions issued by the U.S. Department of Agriculture for use as sources...

  3. 硫酸钙防垢剂的合成与性能评价%Synthesis and Performance Evaluation of Inhibitor for Calcium Sulfate Scale

    Institute of Scientific and Technical Information of China (English)

    李建波; 钟小芳; 李永会; 税敏; 任卉

    2012-01-01

    A scale inhibitor, poly(maleic anhydride-acrylic acid-sodium allylsulfonate) terpolymer(BSI), was synthesized by the copolymerization of maleic anhydride, acrylic acid and sodium allylsulfonate with ammonium persulfate as the initiator. The effects of BSI concentration, temperature, time, pH, NaCl concentration and the concentrations of scale-forming ions(Ca2+and SO2-4) on the scale inhibition rate of BSI for calcium sulfate scale were studied. The effect of the BSI concentration on the scale inhibition rate with high Ca2+and SO2-4 concentrations was investigated. The results show that the scale inhibition rate would be 99.0% under the conditions of 70 ℃, 25 h, p(BSI) 3 mg/L, c(Ca2+) 0.1 mol/L, c(SO2-4) 0.1 mol/L, system pH 8 and p(NaCl) 7.5 g/L. The scale-forming ion concentration has a great influence on the scale inhibition rate. With increasing the BSI concentration, its scale inhibition effect for the solution with high scale-forming ion concentration is better and under the conditions of c(Ca2+) 0.6 mol/L, c(SO2-4) 0.6 mol/L and p(BSI) 220 mg/L the scale inhibition rate can reach 99.0%. According to the characteristics of the molecular structure of BSI, its inhibition mechanism was analyzed, in which BSI and Ca formed a complex. The dispersion flocculation and lattice distortion of BSI were discussed also.%以顺丁烯二酸酐、丙烯酸和烯丙基磺酸钠为原料,以过硫酸铵为引发剂,经共聚反应制得硫酸钙防垢剂聚顺丁烯二酸酐-丙烯酸-烯丙基磺酸钠三元共聚物(BSl);考察了BSI含量、温度、时间、体系pH、NaCl含量、成垢离子(Ca2+和SO42-)浓度对防垢率的影响,同时考察了BSI含量对高浓度成垢离子溶液防垢率的影响.实验结果表明,在70℃、25 h、ρ(BSI) =3mg/L、c (Ca2+)=c(SO42-) =0.1 mol/L、体系pH=8、ρ(NaCl) =7.5 g/L的条件下,防垢率为99.0%.成垢离子浓度对BSI的防垢率影响很大,对于高浓度成垢离子溶液,增加BSI用量仍可使其具有较

  4. Combination of low calcium with Y-27632 rock inhibitor increases the proliferative capacity, expansion potential and lifespan of primary human keratinocytes while retaining their capacity to differentiate into stratified epidermis in a 3D skin model.

    Directory of Open Access Journals (Sweden)

    Xanthe L Strudwick

    Full Text Available Human keratinocytes are difficult to isolate and have a limited lifespan. Traditionally, immortalised keratinocyte cell lines are used in vitro due to their ability to bypass senescence and survive indefinitely. However these cells do not fully retain their ability to differentiate in vitro and they are unable to form a normal stratum corneum in organotypic culture. Here we aimed to generate a pool of phenotypically similar keratinocytes from human donors that could be used in monolayer culture, without a fibroblast feeder layer, and in 3D human skin equivalent models. Primary human neonatal epidermal keratinocytes (HEKn were cultured in low calcium, (0.07 mM media, +/-10 μM Y-27632 ROCK inhibitor (HEKn-CaY. mRNA and protein was extracted and expression of differentiation markers Keratin 14 (K14, Keratin 10 (K10 and Involucrin (Inv assessed by qRT-PCR and Western blotting. The differentiation potential of the HEKn-CaY cultures was assessed by increasing calcium levels and removing the Y-27632 for 72 hrs prior to assessment of K14, K10 and Inv. The ability of the HEKn-CaY, to form a stratified epithelium was assessed using a human skin equivalent (HSE model in the absence of Y-27632. Increased proliferative capacity, expansion potential and lifespan of HEKn was observed with the combination of low calcium and 10 μM ROCK inhibitor Y-27632. The removal of Y-27632 and the addition of high calcium to induce differentiation allowed the cells to behave as primary keratinocytes even after extended serial passaging. Prolonged lifespan HEK-CaYs were capable of forming an organised stratified epidermis in 3D HSE cultures, demonstrating their ability to fully stratify and retain their original, primary characteristics. In conclusion, the use of 0.07 mM Calcium and 10 μM Y-27632 in HEKn monocultures provides the opportunity to culture primary human keratinocytes without a cell feeder layer for extended periods of culture whilst retaining their ability to

  5. Nitrification Inhibitors: A Perspective Tool to Mitigate Greenhouse Gas Emissions from Rice Soils

    Directory of Open Access Journals (Sweden)

    Sandeep K. Malyan

    2016-08-01

    Full Text Available Rice fields are significant contributors of greenhouse gases mainly methane and nitrous oxide to the atmosphere. Increasing concentrations of these greenhouse gases play significant role in changing atmospheric chemistry such as mean air temperature, rainfall pattern, drought, and flood frequency. Mitigation of greenhouse gases for achieving sustainable agriculture without affecting economical production is one the biggest challenge of twenty first century at national and global scale. On the basis of published scientific studies, we hereby assess the use of nitrification inhibitors for greenhouse gas mitigation from rice soil. Biologically oxidation of ammonium to nitrate is termed as nitrification and materials which suppress this process are known as nitrification inhibitors. Soil amendment by addition of certain nitrification inhibitors such as neem oil coated urea, nimin-coated urea; dicyandiamide, encapsulated calcium carbide, and hydroquinone reduce cumulative methane and nitrous oxide emission from rice. Firstly, these inhibitors reduce nitrous oxide emissions both directly by nitrification (by reducing NH4+ to NO3- as well as indirectly by de-nitrification (by reducing NO3- availability in soil. Secondly, methane emission from rice soil can be reduced by enhancing methane oxidation and suppressing methane production and further by reducing the aerenchymal transportation through rice plant. Application of some of the nitrification inhibitors such as calcium carbide and encapsulated calcium carbide reduce methane production by releasing acetylene gas which helps in reducing the population of methanogenic microbes in the soil. Application of nitrification inhibitors also helps to maintain soil redox potential at higher level subsequently reducing cumulative methane emission from soil. Plant derived organic nitrification inhibitors (neem oil, neem cake, karanja seed extract are eco-friendly and possess substantial greenhouse gas mitigation

  6. Brotação de gemas em macieiras 'Imperial Gala' e 'Fuji Suprema' pelo uso de Erger® e nitrato de cálcio Budbreak in 'Imperial Gala' and 'Fuji Suprema' apples by use of Erger and calcium nitrate

    Directory of Open Access Journals (Sweden)

    Fernando José Hawerroth

    2010-06-01

    induction of temperate fruit trees, the high toxicity showed by these compounds is one of the main problems related to its use. Preliminary results indicated that Erger®, an organic nitrogen compound, combined with calcium nitrate, has similar effect to hydrogen cyanamide, with the advantage of being less dangerous to the environment. Thus, the present study aimed to evaluate the efficiency of Erger® and calcium nitrate as budbreak promoter in apple trees. The experiment was carried out in Caçador/SC, in 2007, where was done the application of different budbreak promoters in 'Imperial Gala' and 'Fuji Suprema' apples. The budbreak promoters tested were Erger® 3% + calcium nitrate 3%, Erger® 5% + calcium nitrate 5%, Erger® 7% + calcium nitrate 7%, mineral oil 3.2% + 0.34% hydrogen cyanamide and control (without application. It was evaluated occurrence dates of early, full and end blooming stages, budbreak of axillary and terminal buds, axillary budbreak uniformity and fruit set. The budbreak promoters increased significantly axillary and terminal budbreak, and it increased the budbreak uniformity and the blooming overlap of 'Imperial Gala' and 'Fuji Suprema' apples. Because of negative effects on fruit set of 'Imperial Gala' apples, it is indicated Erger® and calcium nitrate application at concentrations below 7%.

  7. 土壤施钙对芒果果实钾、钙、镁含量及品质的影响%Effects of different lime nitrate application rates on potassium, calcium and magnesium content and quality in mango

    Institute of Scientific and Technical Information of China (English)

    李华东; 白亭玉; 郑妍; 张贺; 林电

    2014-01-01

    以“台农1号”芒果为试材,田间试验研究了花前土施不同用量硝酸钙对芒果果实钾、钙、镁含量及产量、品质的影响。结果表明:(1)与不施钙相比,土施钙肥可明显提高果实糖酸比,其原因主要是降低了可滴定酸含量,提高了可溶性糖含量,同时可显著提高果实Vc含量,降低贮藏期果实发病率,在土施钙150 g/株时产量最高,增产率为14.25%。(2)在一定钙用量范围内,土施钙肥可显著提高果肉钙含量,使果皮、果肉与果核的钾、镁含量下降。(3)果皮、果肉及果核钙含量与钙肥用量呈正相关,钾、镁含量与钙肥用量呈负相关。(4)果实可溶性糖含量、 Vc含量及糖酸比与钙肥用量呈正相关,果实可溶性固形物含量、可滴定酸含量、失重率、发病率与钙肥用量呈负相关。土壤增施钙肥有利于提高芒果果实品质,提高果实耐贮性。%A field trial was undertaken to evaluate the effects of applying Ca( NO3 ) 2 in soil before flower period on the contents of potassium, calcium, magnesium and quality of “tainung No. 1” mango. The results showed that: (1) Compare with the results of the control, applying calcium fertilizer could obviously increase the fruit sugar acid ratio because of the increase of content of soluble sugars and acidity reduced, and improve the vitamin C in the fruit, reduce the rotten fruit rate during stor-age. The highest yield occurred when 150 g/plant calcium was applicated, and the yield increased by 14. 25% compared to the control. (2) By applying calcium fertilizer, the calcium content of pulp in fruit was significantly increased, the magnesi-um and potassium contents of peel, pulp and seed in fruit reduced. (3) The calcium contents of peel, pulp and seed in fruit had positive correlation with the calcium application amounts, and the potassium and magnesium contents of peel, pulp and seed in fruit had negative correlation with

  8. Genetic basis for nitrate resistance in Desulfovibrio strains

    Directory of Open Access Journals (Sweden)

    Hannah eKorte

    2014-04-01

    Full Text Available Nitrate is an inhibitor of sulfate-reducing bacteria (SRB. In petroleum production sites, amendments of nitrate and nitrite are used to prevent SRB production of sulfide that causes souring of oil wells. A better understanding of nitrate stress responses in the model SRB, Desulfovibrio vulgaris Hildenborough and Desulfovibrio alaskensis G20, will strengthen predictions of environmental outcomes. Nitrate inhibition of SRB has historically been considered to result from the generation of small amounts of nitrite, to which SRB are quite sensitive. Here we explored the possibility that nitrate might inhibit SRB by a mechanism other than through nitrite inhibition. We found that nitrate-stressed D. vulgaris cultures grown in lactate-sulfate conditions eventually grew in the presence of high concentrations of nitrate, and their resistance continued through several subcultures. Nitrate consumption was not detected over the course of the experiment, suggesting adaptation to nitrate. With high-throughput genetic approaches employing TnLE-seq for D. vulgaris and a pooled mutant library of D. alaskensis, we determined the fitness of many transposon mutants of both organisms in nitrate stress conditions. We found that several mutants, including homologs present in both strains, had a greatly increased ability to grow in the presence of nitrate but not nitrite. The mutated genes conferring nitrate resistance included the gene encoding the putative Rex transcriptional regulator (DVU0916/Dde_2702, as well as a cluster of genes (DVU0251-DVU0245/Dde_0597-Dde_0605 that is poorly annotated. Follow-up studies with individual D. vulgaris transposon and deletion mutants confirmed high-throughput results. We conclude that, in D. vulgaris and D. alaskensis, nitrate resistance in wild-type cultures is likely conferred by spontaneous mutations. Furthermore, the mechanisms that confer nitrate resistance may be different from those that confer nitrite resistance.

  9. Beyond-root calcium fertilization of apple trees

    Directory of Open Access Journals (Sweden)

    Kazimierz Słowik

    2013-12-01

    Full Text Available Investigations were performed in the period 1977-1979 on the apple tree cultivar 'Fantazja', on rootstock A 2, M 7 and MM 106 on the effect of spraying with solution containing calcium on the incidence of bitter pit, breakdown, calcium content in the fruit flesh and other features of the fruits. Threefold spraying with calcium nitrate, calcium chloride or Anti-Stipp significantly limited the appearance of bitter pit and breakdown.

  10. Influence of proton pump inhibitors and histamine H2 receptor antagonists on serum phosphorus level control by calcium carbonate in patients undergoing hemodialysis: a retrospective medical chart review

    OpenAIRE

    Tatsuzawa, Masaomi; Ogawa, Ryuichi; OHKUBO, Atsushi; Shimojima, Kazuyo; Maeda, Kunimi; Echizen, Hirotoshi; Miyazaki, Akihisa

    2016-01-01

    Background Hyperphosphatemia is one of the common complications in patients undergoing hemodialysis. Although calcium carbonate (CaC) is often used to control serum inorganic phosphorus level in dialysis patients, co-administration of gastric acid reducers (ARs) may interfere with the phosphate binding effect of CaC. We performed a retrospective medical chart review to study whether ARs attenuate the hypophosphatemic effect of CaC in patients undergoing hemodialysis. Methods One hundred and e...

  11. An open-label, randomized, controlled, 4-week comparative clinical trial of barnidipine hydrochloride, a calcium-channel blocker, and benazepril, an angiotensin-converting enzyme inhibitor, in Chinese patients with renal parenchymal hypertension.

    Science.gov (United States)

    Chen, X; Zheng, F; Chen, P; Tang, L; Wei, R; Yu, Y; Su, Y; Kikkawa, T; Yamamoto, M

    2006-01-01

    This study compared barnidipine, a calcium-channel blocker, and benazepril, an angiotensin-converting enzyme inhibitor, in 85 Chinese patients with renal parenchymal hypertension (diastolic blood pressure range 95 - 110 mmHg). Patients were randomly assigned to receive either 10 mg barnidipine or 10 mg benazepril orally daily for 4 weeks. In patients with diastolic blood pressure > 90 mmHg after 2 weeks of treatment, the dose of barnidipine or benazepril was increased by 5 or 10 mg, respectively. Both the barnidipine-treated group (n = 43) and the benazepril-treated group (n = 42) showed significant mean reductions from baseline in sitting systolic and diastolic blood pressures. The decrease in diastolic blood pressure with benazepril was significantly greater than with barnidipine treatment. Sitting heart rate was not changed by either drug. There was no significant difference in adverse events between the two groups. Barnidipine is similar to benazepril for the treatment of renal parenchymal hypertension.

  12. THE DYNAMIC EXPERIMENT OF THRESHOLD SCALING INHIBITORS AGAINST THE PRECIPITATION OF CALCIUM CARBONATE IN AQUEOUS SOLUTION%非化学配比阻垢剂对水垢析晶过程影响的动力学研究

    Institute of Scientific and Technical Information of China (English)

    李广兵; 方健; 李杰

    2001-01-01

    The effect of two threshold indibitors, sodium polyphosphate(SPP) and polypropylene acid (PAA) on the precipitation of calcium carbonate were investigated. The formation of species from solution was computed from the recorded conductivity values and mass-balance and charge-balance equations by successive approximations for the ionic strenght. The nano-scale crystals of calcium carbonate was seeded. This made the experiments reproducible. The inhibitors' threshold in our experiments was independent on the solution's supersaturation and inhibitor effectiveness defined by static method was sensitive to supersaturation.%我们基于溶液电离平衡、质子平衡、离子活度原理以及法拉第分布电解定律,建立了精确测量碳酸钙过饱和溶液在析晶过程中所有离子变化的试验系统,并使用该系统研究了阻垢剂聚丙烯酸和多聚磷酸钠对碳酸钙析晶过程的影响。试验中使用了植晶的方法,保证了试验具有高重复性。试验研究表明,静态法所定义的阻垢率数值易受溶液过饱和度的影响,但是动力学方法测量的阻垢剂的阻垢阈值不受影响。动力学的研究和静态法的结合加深了我们对阻垢剂的阻垢过程的了解。

  13. Regulatory Effects of Combined Application of Organic Manures with Inorganic Fertilizers and Nitrification Inhibitors on Nitrate Contamination in Garden Ecosystem%有机无机肥配施及硝化抑制剂对菜园生态系统硝酸盐污染的调控效应

    Institute of Scientific and Technical Information of China (English)

    黄运湘; 吴名宇; 张杨珠; 王翠红

    2012-01-01

    为探明有机无机肥配施及其与硝化抑制剂配合施用对菜园生态系统氮素的吸收利用和迁移转化的影响,采用田间小区试验,对小白菜—土壤生态系统硝酸盐污染状况进行了较系统的研究.结果表明,有机无机肥配施及配合施用硝化抑制剂HQ、DCD和TU均不同程度地降低小白菜硝酸盐和亚硝酸盐的含量.减少耕层土壤中硝酸盐的积累,提高耕层土壤中铵态氮的含量.%To determine the inhibiting effects of combined application of organic manures with inorganic fertilizers and combined application of organic manures with inorganic fertilizers and nitrification inhibitors on accumulation of nitrate and nitrites in vegetable plants, the red garden soil developed from the Quaternary red clay and the field plot experiment were carried out to study the pollution conditions of nitrate in garden soil ecosystem. The results showed that the combined application of organic manures with inorganic fertilizers and nitrification inhibitors (HQ, DCD and TU) all can reduce the contents of nitrate and nitrites in pakchoi at different levels, while obviously increase the contents of Vc and soluble sugar in pakchoi, therefore, it is an effective techniques for producing quality and high-yield vegetables. NO3" and NH4* can be adsorbed and maintained by the tested soil to some degree, and N03" leaching was discovered in soil profile, but non-pollution caused to groundwater.

  14. Effect of composition on the density of multi-component molten nitrate salts.

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, Robert W.

    2009-12-01

    The density of molten nitrate salts was measured to determine the effects of the constituents on the density of multi-component mixtures. The molten salts consisted of various proportions of the nitrates of potassium, sodium, lithium and calcium. Density measurements ere performed using an Archimedean method and the results were compared to data reported in the literature for the individual constituent salts or simple combinations, such as the binary Solar Salt mixture of NaNO3 and KNO3. The addition of calcium nitrate generally ncreased density, relative to potassium nitrate or sodium nitrate, while lithium nitrate decreased density. The temperature dependence of density is described by a linear equation regardless of composition. The molar volume, and thereby, density of multi-component mixtures an be calculated as a function of temperature using a linear additivity rule based on the properties of the individual constituents.

  15. Agricultural nitrate pollution

    DEFF Research Database (Denmark)

    Anker, Helle Tegner

    2015-01-01

    Despite the passing of almost 25 years since the adoption of the EU Nitrates Directive, agricultural nitrate pollution remains a major concern in most EU Member States. This is also the case in Denmark, although a fairly strict regulatory regime has resulted in almost a 50 per cent reduction...

  16. Nitrate Leaching Index

    Science.gov (United States)

    The Nitrate Leaching Index is a rapid assessment tool that evaluates nitrate (NO3) leaching potential based on basic soil and climate information. It is the basis for many nutrient management planning efforts, but it has considerable limitations because of : 1) an oversimplification of the processes...

  17. Calcium supplements

    Science.gov (United States)

    ... do not help. Always tell your provider and pharmacist if you are taking extra calcium. Calcium supplements ... 2012:chap 251. The National Osteoporosis Foundation (NOF). Clinician's Guide to prevention and treatment of osteoporosis . National ...

  18. Effects of Angiotensin Ⅱ and ACE Inhibitor, Captopril on L-type Calcium Current and Sodium Current of Single Guinea Myocytes

    Institute of Scientific and Technical Information of China (English)

    徐延敏; 黄体钢; 陈元禄

    2002-01-01

    Objectives To investigateeffect of AngⅡ, captopril on single guinea myocytes onL - type calcium current and sodium current. MethodsMembrane patch clamp whole cell recording tech-nique was used to investigate effect of angⅡ, captoprilon L- Ca maximum current density and sodium maxi-mum current density. Resutls AngⅡ increased themaximum current density compared with control afterpeffused 5 min, 357.7±219.7 Vs 279.5±240.5PA/PF, increase rate is 27.9 %, the shape of current- voltage relationship curve was unchanged, peaked at+ 10 my, indicated that angⅡ increased L- Ca cur-rent density in voltage -dependent. After perfusedwith captopril, captopril ± angⅡ 3, 5 rmin, L-Cacurrent was recorded, results suggest L - Ca maximumcurrent density decreased significantly compared withcontrol, in captopril group, 128.4 ± 92.6Vs286.2 ±89.7, 66.7 ±68.3Vs 286.2 ± 89.7, respectively, rateof inhibition is 55.1%, 76.6 %, respectively. L - Cacurrent further decreased in captopril perfused 5 mincompared with 3 rmin, 66.7 ± 68.3 Vs 128.4 ± 92.6,in captopril + angⅡ group, L- Ca current decreasedgreatly in 3, 5 min than control, 143.4 ± 117.6Vs267.7±141.4, 96.4±82.5 Vs 267.7+141.4, re-spectively, rate of inhibition is 46.4 %, 63.9 % re-spectively. We also investigated effect of captopril onNa current, which decreased significantly in 1 rmin and3 rmin compared with control, 939.1 ±319. 1 Vs1398.0 ± 144.6 PA/PF, 469.95±314.9 Vs 1398.0±144.6 PA/PF, respectively, rate of inhibition is32.8 %, 66. 3 %, respectively. Na current density de-creased significantly in 3 min compared with 1 min,469.9 ± 314.9 Vs 939. 1 ± 319. 1PA/PF, rate of in-hibition is 49.9 % . Conclusions Angiotensin Ⅱexerts increased maximum current density of L - Ca involtage dependent, captopril decreased maximum cur-rent density of L - Ca in voltage dependent, decreasedsodium maximum current density, which is the promi-nently antiarrhythmia mechanisms through inhibition ofangiotensin Ⅱ evoked

  19. Effects of Nitrification Inhibitor Dicyandiamide on Ammonium and Nitrate Nitrogen Transformations in Cinnamon Soil%硝化抑制剂双氰胺对褐土中尿素转化的影响

    Institute of Scientific and Technical Information of China (English)

    刘瑜; 串丽敏; 安志装; 赵同科; 赵丽平; 高忠义; 李英

    2011-01-01

    An aerobic soil incubation experiment was carried out to study the effects of different levels of the nitrification inhibitor dicyandi-amide( Dicyandiamide, DCD) on the transformations of nitrate nitrogen and ammonia nitrogen in Beijing cinnamon soil. The results showed that during the 44 days incubation period, the application of DCD resulted in significanT1y higher concentrations of soil NH4+-N and lower concentrations of NO3--N in the soil. When the application rate of DCD was 1%, 2%, 3%, 4% and 5%, the average soil NH4-N concentration was increased by 29.50%,71.84%, 99.73%, 98.90% and 139.69%, the average NO3--N·concentration was decreased by 3.71%, 15.61%, 21.07%, 33.57% and 37.90%, compared with the urea control respectively. The comprehensive index of soil apparent nitrification rate, reflecting the change rule for NO3--N and NH4+-N, was decreased by 12.18%、35.35% 、44.82%、48.18% and 59.93%, respectively. And the reaching balance date of them delayed 7 days, 14 days, 14 days and 21days at the levels of 1%, 2%, 3% and 4%, respectively. It has showed a rising trend until the incubation end at the level of 5%, always lower than the control, and the increase rate was significanT1y decreased by 39.32%,40.00%,52.27% at the levels of 2%, 3%, 4%, respectively. Based on a combination of crop N requirements, environmental benefits and economic factors, the optimum rate of DCD was 4%, with a good inhibitory effect of ammonium oxidation, whilst helping to improve nitrogen use efficiency, and reducing environmental impacts.%采用好气土壤培养法,研究北京地区典型褐土中添加不同浓度水平硝化抑制剂双氰胺(Dicyandiamide,DCD)条件下土壤中铵态氮、硝态氮变化规律.结果表明,44d培养期内,DCD施用显著提高土壤中NH+4 -N浓度,降低NO-3 -N浓度,1%、2%、3%、4%和5%DCD用量处理条件土壤NH+4 -N平均浓度比单施尿素对照处理分别升高29.50%、71.84%、99.73%、98.90%和139.69%,NO-3

  20. Bioactivation of organic nitrates and the mechanism of nitrate tolerance.

    Science.gov (United States)

    Klemenska, Emila; Beresewicz, Andrzej

    2009-01-01

    Organic nitrates, such as nitroglycerin, are commonly used in the therapy of cardiovascular disease. Long-term therapy with these drugs, however, results in the rapid development of nitrate tolerance, limiting their hemodynamic and anti-ischemic efficacy. In addition, nitrate tolerance is associated with the expression of potentially deleterious modifications such as increased oxidative stress, endothelial dysfunction, and sympathetic activation. In this review we discuss current concepts regarding the mechanisms of organic nitrate bioactivation, nitrate tolerance, and nitrate-mediated oxidative stress and endothelial dysfunction. We also examine how hydralazine may prevent nitrate tolerance and related endothelial dysfunction.

  1. The CamKKβ Inhibitor STO609 Causes Artefacts in Calcium Imaging and Selectively Inhibits BKCa in Mouse Carotid Body Type I Cells.

    Science.gov (United States)

    Jurcsisn, Jennifer G; Pye, Richard L; Ali, Jon; Barr, Barbara L; Wyatt, Christopher N

    2015-01-01

    It has previously been reported that AMP-activated protein kinase (AMPK) may be critical for hypoxic chemotransduction in carotid body type I cells. This study sought to determine the importance of the regulatory upstream kinase of AMPK, CamKKβ, in the acute response to hypoxia in isolated mouse type I cells.Initial data indicated several previously unreported artefacts associated with using the CamKKβ inhibitor STO609 and Ca(2+) imaging techniques. Most importantly Fura-2 and X-Rhod1 imaging revealed that STO609 quenched emission fluorescence even in the absence of intracellular Ca(2+) ([Ca(2+)](I)). Furthermore, STO609 (100 μM) rapidly inhibited outward macroscopic currents and this inhibition was abolished in the presence of the selective BK(Ca) inhibitor paxilline.Taken together these data suggest that ST0609 should be used with caution during Ca(2+) imaging studies as it can directly interact with Ca(2+) binding dyes. The rapid inhibitory effect of STO609 on BK(Ca) was unexpected as the majority of studies using this compound required an incubation of approximately 10 min to inhibit the kinase. Furthermore, as AMPK activation inhibits BK(Ca), inhibiting AMPK's upstream kinases would, if anything, be predicted to have the opposite effect on BK(Ca). Future work will determine if the inhibition of BK(Ca) is via CamKKβ or via an off target action of STO609 on the channel itself.

  2. Agricultural nitrate pollution

    DEFF Research Database (Denmark)

    Anker, Helle Tegner

    2015-01-01

    Despite the passing of almost 25 years since the adoption of the EU Nitrates Directive, agricultural nitrate pollution remains a major concern in most EU Member States. This is also the case in Denmark, although a fairly strict regulatory regime has resulted in almost a 50 per cent reduction...... in nitrogen leaching since the mid-80s. Nevertheless, further effort is needed, particularly in ecologically sensitive areas. This article discusses different regulatory approaches – and in particular the need for a differentiated nitrate regulation tailored to meet site-specific ecological demands – from...... of the mandatory specification standards of the Nitrates Directive combined with additional instruments to address the need for severe restrictions on fertiliser use or cultivation practices in the most ecologically vulnerable areas....

  3. Relationship between Plasma Serine Peptidase Inhibitor and Calcium of Dairy Cows during Transition Period%丝氨酸蛋白抑制剂与围产期奶牛血钙的关系

    Institute of Scientific and Technical Information of China (English)

    舒适; 夏成; 徐闯; 张洪友; 吴凌; 郑家三; 杨龙蛟

    2012-01-01

    This study investigated relationship between plasma serine peptidase inhibitor (SERPIN) and calcium of dairy cows in transition period. At calving, days 14-7 before calving, and days after calving the dairy cows were chosen and divided into hypocaleaemia group { 〈 2.20 mmol/L, T} and normal group (2.20-3.5 mmol/L, C}, 3 each group. Plasma SERPIN abundance were measured using western blotting. Results showed that abundance of plasma SERPIN was upregulated in plasma of dairy cows with hypocal- caemia. Conclusion obtained that we first confirm that there is a negative association of SERPIN and calci- um in plasma, which implies that calcium may regulate blood coagulation and immune function of dairy cows by SERPIN pathway.%本研究旨在了解围产期低血钙奶牛与正常奶牛的血浆Serine peptidase inhibitor(SERPIN)与血钙之间的关系。在分娩当天、产前14~7d和产后7~14d根据血钙浓度将实验牛分为正常对照组(2.20~3.5mmol/L,C)和低血钙组(〈2.20mmol/L,T),每组3头。利用Westernblotting检测试验牛血浆SERPIN丰度。结果显示:SPI蛋白在奶牛发生低血钙时,表达上调。结论:本试验首次证明了血浆SERPIN与血钙浓度呈负关联,血钙可能通过SERPIN途径调节机体的凝血过程和免疫功能。

  4. A novel Glycine soja cysteine proteinase inhibitor GsCPI14, interacting with the calcium/calmodulin-binding receptor-like kinase GsCBRLK, regulated plant tolerance to alkali stress.

    Science.gov (United States)

    Sun, Xiaoli; Yang, Shanshan; Sun, Mingzhe; Wang, Sunting; Ding, Xiaodong; Zhu, Dan; Ji, Wei; Cai, Hua; Zhao, Chaoyue; Wang, Xuedong; Zhu, Yanming

    2014-05-01

    It has been well demonstrated that cystatins regulated plant stress tolerance through inhibiting the cysteine proteinase activity under environmental stress. However, there was limited information about the role of cystatins in plant alkali stress response, especially in wild soybean. Here, in this study, we focused on the biological characterization of a novel Glycine soja cystatin protein GsCPI14, which interacted with the calcium/calmodulin-binding receptor-like kinase GsCBRLK and positively regulated plant alkali stress tolerance. The protein-protein interaction between GsCBRLK and GsCPI14 was confirmed by using split-ubiquitin based membrane yeast two-hybrid analysis and bimolecular fluorescence complementation assay. Expression of GsCPI14 was greatly induced by salt, ABA and alkali stress in G. soja, and GsCBRLK overexpression (OX) in Glycine max promoted the stress induction of GmCPI14 expression under stress conditions. Furthermore, we found that GsCPI14-eGFP fusion protein localized in the entire Arabidopsis protoplast and onion epidermal cell, and GsCPI14 showed ubiquitous expression in different tissues of G. soja. In addition, we gave evidence that the GST-GsCPI14 fusion protein inhibited the proteolytic activity of papain in vitro. At last, we demonstrated that OX of GsCPI14 in Arabidopsis promoted the seed germination under alkali stress, as evidenced by higher germination rates. GsCPI14 transgenic Arabidopsis seedlings also displayed better growth performance and physiological index under alkali stress. Taken together, results presented in this study demonstrated that the G. soja cysteine proteinase inhibitor GsCPI14 interacted with the calcium/calmodulin-binding receptor-like kinase GsCBRLK and regulated plant tolerance to alkali stress.

  5. Slow-release of methanogenic inhibitors derived from encapsulated calcium carbide using paraffin wax and/or rosin: matrix optimization and diffusion characteristics.

    Science.gov (United States)

    Tiantao, Zhao; Youcai, Zhao; Lijie, Zhang; Haoquan, Chen; Feng, Shi; Haiyan, Zhou

    2011-11-01

    Acetylene has been found to significantly inhibit biological activity of methanogens and thus might be applicable for reducing the generation and emission of methane from municipal solid waste landfills. However, acetylene is gaseous and so it is considered physically infeasible to directly apply this gas to waste in landfill conditions. In the present study, a novel acetylene release mechanism was tested, using a matrix of acetylene entrapped in high hydrophobic paraffin wax and/or rosin and calcium carbide capsules with a ratio of 1.0 g g(-1) matrix and a diameter of 10 mm to facilitate the gradual release of acetylene. A diffusion mechanism model (Q = &b.gamma; × t (0.5)) for the matrix was derived based on the T. Higuchi equation, and the effective diffusion coefficients (D(e)) were acquired by linear fitting. Additionally, it was found that D(e) remained constant when the rosin content was up to more than 20% g g(-1) matrix.

  6. Osteoblasts detect pericellular calcium concentration increase via neomycin-sensitive voltage gated calcium channels.

    Science.gov (United States)

    Sun, Xuanhao; Kishore, Vipuil; Fites, Kateri; Akkus, Ozan

    2012-11-01

    The mechanisms underlying the detection of critically loaded or micro-damaged regions of bone by bone cells are still a matter of debate. Our previous studies showed that calcium efflux originates from pre-failure regions of bone matrix and MC3T3-E1 osteoblasts respond to such efflux by an increase in the intracellular calcium concentration. The mechanisms by which the intracellular calcium concentration increases in response to an increase in the pericellular calcium concentration are unknown. Elevation of the intracellular calcium may occur via release from the internal calcium stores of the cell and/or via the membrane bound channels. The current study applied a wide range of pharmaceutical inhibitors to identify the calcium entry pathways involved in the process: internal calcium release from endoplasmic reticulum (ER, inhibited by thapsigargin and TMB-8), calcium receptor (CaSR, inhibited by calhex), stretch-activated calcium channel (SACC, inhibited by gadolinium), voltage-gated calcium channels (VGCC, inhibited by nifedipine, verapamil, neomycin, and ω-conotoxin), and calcium-induced-calcium-release channel (CICRC, inhibited by ryanodine and dantrolene). These inhibitors were screened for their effectiveness to block intracellular calcium increase by using a concentration gradient induced calcium efflux model which mimics calcium diffusion from the basal aspect of cells. The inhibitor(s) which reduced the intracellular calcium response was further tested on osteoblasts seeded on mechanically loaded notched cortical bone wafers undergoing damage. The results showed that only neomycin reduced the intracellular calcium response in osteoblasts, by 27%, upon extracellular calcium stimulus induced by concentration gradient. The inhibitory effect of neomycin was more pronounced (75% reduction in maximum fluorescence) for osteoblasts seeded on notched cortical bone wafers loaded mechanically to damaging load levels. These results imply that the increase in

  7. Nitrate sensing by the maize root apex transition zone: a merged transcriptomic and proteomic survey.

    Science.gov (United States)

    Trevisan, Sara; Manoli, Alessandro; Ravazzolo, Laura; Botton, Alessandro; Pivato, Micaela; Masi, Antonio; Quaggiotti, Silvia

    2015-07-01

    Nitrate is an essential nutrient for plants, and crops depend on its availability for growth and development, but its presence in agricultural soils is far from stable. In order to overcome nitrate fluctuations in soil, plants have developed adaptive mechanisms allowing them to grow despite changes in external nitrate availability. Nitrate can act as both nutrient and signal, regulating global gene expression in plants, and the root tip has been proposed as the sensory organ. A set of genome-wide studies has demonstrated several nitrate-regulated genes in the roots of many plants, although only a few studies have been carried out on distinct root zones. To unravel new details of the transcriptomic and proteomic responses to nitrate availability in a major food crop, a double untargeted approach was conducted on a transition zone-enriched root portion of maize seedlings subjected to differing nitrate supplies. The results highlighted a complex transcriptomic and proteomic reprogramming that occurs in response to nitrate, emphasizing the role of this root zone in sensing and transducing nitrate signal. Our findings indicated a relationship of nitrate with biosynthesis and signalling of several phytohormones, such as auxin, strigolactones, and brassinosteroids. Moreover, the already hypothesized involvement of nitric oxide in the early response to nitrate was confirmed with the use of nitric oxide inhibitors. Our results also suggested that cytoskeleton activation and cell wall modification occurred in response to nitrate provision in the transition zone.

  8. The calcium oxotellurate(IV) nitrates Ca5Te4O12(NO3)2(H2O)2 and Ca6Te5O15(NO3)2 . Non-classic order/disorder polytypism and a rigid framework structure

    Science.gov (United States)

    Stöger, Berthold; Weil, Matthias

    2013-04-01

    Single crystals of two novel calcium oxotellurate(IV) nitrates were grown under hydrothermal conditions and were structurally characterized by X-ray diffraction. Ca_5Te_4{O}_{12}(NO_3)_2(H_2O)_2 [Cc, Z=4, a=25.258(3) Å, b=5.7289(7) Å, c=17.0066(19) Å, β =124.377(2)°, R[F^2 > 2σ (F^2)]=0.043, 4083 F^2 data, 281 parameters] can be described as a non-classic order/disorder (OD) structure, which fulfills the basic principle of OD theory, viz. local equivalence of polytypes, but does not strictly follow the vicinity condition (VC) of OD theory. The structure is made up from an alternating stacking of non-polar layers composed of isolated [TeO_3] units and Ca^{2+} ions and polar layers containing NO_3^- ions and water molecules. The electron lone-pairs of the [TeO_3] units protrude into the free space of the anion/water layers. The crystal under investigation was a non-classic OD-twin of domains of a maximum degree of order (MDO). At the twin plane a fragment of the second MDO polytype is located. The main building blocks of Ca_6Te_5{O}_{15}(NO_3)_2 [P2_1/c, Z=4, a=15.494(2) Å, b=5.6145(7) Å, c=39.338(4) Å, β =142.480(5)°, R[F^2 > 2σ (F^2)]=0.043, 3026 F^2 data, 307 parameters] are isolated [TeO_3] units and Ca^{2+} ions which are connected to a three-dimensional framework perforated by channels in which the N atoms of the nitrate anions are located and the electron lone-pairs of the [TeO_3] units protrude. The structure can topologically be derived from the structure of Ca_5Te_4{O}_{12}(NO_3)_2(H_2O)_2 by removing the water molecules and connecting the CaTeO_3 layers with additional [TeO_3] units and Ca^{2+} ions.

  9. Calcium in diet

    Science.gov (United States)

    ... D is needed to help your body use calcium. Milk is fortified with vitamin D for this reason. ... of calcium dietary supplements include calcium citrate and calcium carbonate. Calcium citrate is the more expensive form of ...

  10. Nitrate Leaching Management

    Science.gov (United States)

    Nitrate (NO3) leaching is a significant nitrogen (N) loss process for agriculture that must be managed to minimize NO3 enrichment of groundwater and surface waters. Managing NO3 leaching should involve the application of basic principles of understanding the site’s hydrologic cycle, avoiding excess ...

  11. Nitrate absorption through hydrotalcite reformation.

    Science.gov (United States)

    Frost, Ray L; Musumeci, Anthony W

    2006-10-01

    Thermally activated hydrotalcite based upon a Zn/Al hydrotalcite with carbonate in the interlayer has been used to remove nitrate anions from an aqueous solution resulting in the reformation of a hydrotalcite with a mixture of nitrate and carbonate in the interlayer. X-ray diffraction of the reformed hydrotalcites with a d(003) spacing of 7.60 A shows that the nitrate anion is removed within a 30 min period. Raman spectroscopy shows that two types of nitrate anions exist in the reformed hydrotalcite (a) nitrate bonded to the 'brucite-like' hydrotalcite surface and (b) aquated nitrate anion in the interlayer. Kinetically the nitrate is replaced by the carbonate anion over a 21 h period. Two types of carbonate anions are observed. This research shows that the reformation of a thermally activated hydrotalcite can be used to remove anions such as nitrate from aqueous systems.

  12. 硝酸钙胁迫对水培嫁接茄子氮碳同化的影响%Effects of calcium nitrate stress on nitrogen and carbon metabolism in hy- droponically-grown grafted eggplant seedlings

    Institute of Scientific and Technical Information of China (English)

    魏国平; 朱月林; 唐于银; 杨立飞; 张晓青

    2011-01-01

    -grafted seedlings. The contents of NO3- and NH4+ in the leaves of both grafted and non-grafted eggplant seedlings increased significantly at the early stage of treatment, then decreased significantly, however, the contents of NO3-and NH4+ in grafted seedlings were significantly higher than those of non-grafted seedlings with prolonged stress time. Nitrate reductase (NR) activity in the leaves of grafted eggplant seedlings was significantly higher than that of non-grafted seedlings since the 9th day of treatment. Soluble protein content in the leaves of grafted eggplant seedlings was significantly higher than that of non-grafted seedlings during the whole stress process. Clutamine synthetase (GS) activity in the leaves of eggplant seedlings increased significantly at the early stage of treatment, then decreased significantly, however, GS activity in grafted eggplant seedlings were significantly higher than that of non-grafted seedlings with prolonged stress time. Soluble sugar content in the leaves of grafted eggplant seedlings increased significantly at the early stage of treatment, then decreased significantly, but soluble sugar content in non-grafted eggplant seedlings decreased and was significantly lower than that of grafted seedlings in the whole stress time. Starch content in leaves of grafted eggplant seedlings was significantly higher than that of non-grafted seedlings, but activities of α-amylase and β-amylase in the leaves of grafted eggplant seedlings were both significantly lower than those of non-grafted seedlings. Under stress by excess of Ca( NO3 )2, nitrogen metabolism and carbon metabolism in grafted eggplant seedlings were more efficient than those of non-grafted seedlings. Grafted seedlings were more tolerant to stress by excess of Ca( NO3 )2, according to the efficiency of energy storage and physiological metabolism.

  13. Nitrate source indicators in ground water of the Scimitar Subdivision, Peters Creek area, Anchorage, Alaska

    Science.gov (United States)

    Wang, Bronwen; Strelakos, Pat M.; Jokela, Brett

    2000-01-01

    A combination of aqueous chemistry, isotopic measurement, and in situ tracers were used to study the possible nitrate sources, the factors contributing to the spatial distribution of nitrate, and possible septic system influence in the ground water in the Scimitar Subdivision, Municipality of Anchorage, Alaska. Two water types were distinguished on the basis of the major ion chemistry: (1) a calcium sodium carbonate water, which was associated with isotopically heavier boron and with chlorofluorocarbons (CFC's) that were in the range expected from equilibration with the atmosphere (group A water) and (2) a calcium magnesium carbonate water, which was associated with elevated nitrate, chloride, and magnesium concentrations, generally isotopically lighter boron, and CFC's concentrations that were generally in excess of that expected from equilibration with the atmosphere (group B water). Water from wells in group B had nitrate concentrations that were greater than 3 milligrams per liter, whereas those in group A had nitrate concentrations of 0.2 milligram per liter or less. Nitrate does not appear to be undergoing extensive transformation in the ground-water system and behaves as a conservative ion. The major ion chemistry trends and the presence of CFC's in excess of an atmospheric source for group B wells are consistent with waste-water influences. The spatial distribution of the nitrate among wells is likely due to the magnitude of this influence on any given well. Using an expanded data set composed of 16 wells sampled only for nitrate concentration, a significant difference in the static water level relative to bedrock was found. Well water samples with less than 1 milligram per liter nitrate had static water levels within the bedrock, whereas those samples with greater than 1 milligram per liter nitrate had static water levels near or above the top of the bedrock. This observation would be consistent with a conceptual model of a low-nitrate fractured bedrock

  14. Calcium Electroporation

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gibot, Laure; Madi, Moinecha;

    2015-01-01

    BACKGROUND: Calcium electroporation describes the use of high voltage electric pulses to introduce supraphysiological calcium concentrations into cells. This promising method is currently in clinical trial as an anti-cancer treatment. One very important issue is the relation between tumor cell kill...... efficacy-and normal cell sensitivity. METHODS: Using a 3D spheroid cell culture model we have tested the effect of calcium electroporation and electrochemotherapy using bleomycin on three different human cancer cell lines: a colorectal adenocarcinoma (HT29), a bladder transitional cell carcinoma (SW780......), and a breast adenocarcinoma (MDA-MB231), as well as on primary normal human dermal fibroblasts (HDF-n). RESULTS: The results showed a clear reduction in spheroid size in all three cancer cell spheroids three days after treatment with respectively calcium electroporation (p

  15. Effect of substrate nature on the electrochemical deposition of calcium-deficient hydroxyapatites

    Science.gov (United States)

    Gualdrón-Reyes, A. F.; Domínguez-Vélez, V.; Morales-Morales, J. A.; Cabanzo, R.; Meléndez, A. M.

    2017-01-01

    Calcium phosphates were obtained by reducing nitrate ions to produce hydroxide ions on TiO2/stainless steel and TiO2/titanium electrodes. TiO2 coatings on metallic substrates were prepared by sol-gel dip-coating method. The morphology of deposits was observed by FESEM. Chemical nature of calcium phosphate deposits was identified by Raman micro-spectroscopy and FESEM/EDS microanalysis. Electrochemical behavior of nitrate and nitrite reduction on stainless steel and titanium electrodes was studied by linear sweep voltammetry. In addition, voltammetric study of the calcium phosphate electrodeposition on both electrodes was performed. From these measurements was selected the potential to form a calcium phosphate. A catalytic current associated to nitrate reduction reaction was obtained for stainless steel electrode, leading to significant deposition of calcium phosphate. Ca/P ratio for both substrates was less than 1.67. The formation of calcium deficient hydroxyapatite was confirmed by Raman spectroscopy.

  16. Bioactivity studies of calcium magnesium silicate prepared from eggshell waste by sol–gel combustion synthesis

    Directory of Open Access Journals (Sweden)

    Rajan Choudhary

    2015-06-01

    Full Text Available The present study focused on the synthesis of calcium magnesium silicate (akermanite, Ca2MgSi2O7 using eggshell biowaste (as calcium source, magnesium nitrate and tetraethyl orthosilicate (TEOS as starting materials. Sol–gel combustion method was adopted to obtain calcium magnesium silicate. Citric acid was used as a fuel (reducing agent and nitrate ions present in the metal nitrates acts as an oxidizing agent during combustion process. The characterization of synthesized calcium magnesium silicate was carried out by powder X-ray diffraction (XRD, Fourier transform infrared (FTIR and scanning electron microscopy (SEM techniques. Calcium magnesium silicate crystallite size was observed in nano regime which can effectively mimic natural bone apatite composition. In-vitro bioactivity was investigated by immersing calcium magnesium silicate pellet in simulated body fluid (SBF for three weeks. Results show effective deposition of crystallized hydroxyapatite (HAP layer on its surface and predicting its possibilities for applications in hard tissue regeneration.

  17. Effect of calcium source on structure and properties of sol-gel derived bioactive glasses.

    Science.gov (United States)

    Yu, Bobo; Turdean-Ionescu, Claudia A; Martin, Richard A; Newport, Robert J; Hanna, John V; Smith, Mark E; Jones, Julian R

    2012-12-18

    The aim was to determine the most effective calcium precursor for synthesis of sol-gel hybrids and for improving homogeneity of sol-gel bioactive glasses. Sol-gel derived bioactive calcium silicate glasses are one of the most promising materials for bone regeneration. Inorganic/organic hybrid materials, which are synthesized by incorporating a polymer into the sol-gel process, have also recently been produced to improve toughness. Calcium nitrate is conventionally used as the calcium source, but it has several disadvantages. Calcium nitrate causes inhomogeneity by forming calcium-rich regions, and it requires high temperature treatment (>400 °C) for calcium to be incorporated into the silicate network. Nitrates are also toxic and need to be burnt off. Calcium nitrate therefore cannot be used in the synthesis of hybrids as the highest temperature used in the process is typically 40-60 °C. Therefore, a different precursor is needed that can incorporate calcium into the silica network and enhance the homogeneity of the glasses at low (room) temperature. In this work, calcium methoxyethoxide (CME) was used to synthesize sol-gel bioactive glasses with a range of final processing temperatures from 60 to 800 °C. Comparison is made between the use of CME and calcium chloride and calcium nitrate. Using advanced probe techniques, the temperature at which Ca is incorporated into the network was identified for 70S30C (70 mol % SiO(2), 30 mol % CaO) for each of the calcium precursors. When CaCl(2) was used, the Ca did not seem to enter the network at any of the temperatures used. In contrast, Ca from CME entered the silica network at room temperature, as confirmed by X-ray diffraction, (29)Si magic angle spinning nuclear magnetic resonance spectroscopy, and dissolution studies. CME should be used in preference to calcium salts for hybrid synthesis and may improve homogeneity of sol-gel glasses.

  18. 33 CFR 126.28 - Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate...

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Ammonium nitrate, ammonium nitrate fertilizers, fertilizer mixtures, or nitro carbo nitrate; general provisions. 126.28 Section 126...) WATERFRONT FACILITIES HANDLING OF DANGEROUS CARGO AT WATERFRONT FACILITIES § 126.28 Ammonium...

  19. Nitrate in drinking water

    DEFF Research Database (Denmark)

    Schullehner, Jörg; Hansen, Birgitte; Sigsgaard, Torben

    is highly decentralized and fully relying on simple treated groundwater. At the same time, Denmark has an intensive agriculture, making groundwater resources prone to nitrate pollution. Drinking water quality data covering the entire country for over 35 years are registered in the public database Jupiter......Annual nationwide exposure maps for nitrate in drinking water in Denmark from the 1970s until today will be presented based on the findings in Schullehner & Hansen (2014) and additional work on addressing the issue of private well users and estimating missing data. Drinking water supply in Denmark....... In order to create annual maps of drinking water quality, these data had to be linked to 2,852 water supply areas, which were for the first time digitized, collected in one dataset and connected to the Jupiter database. Analyses of the drinking water quality maps showed that public water supplies...

  20. NITRATE DESTRUCTION LITERATURE SURVEY AND EVALUATION CRITERIA

    Energy Technology Data Exchange (ETDEWEB)

    Steimke, J.

    2011-02-01

    This report satisfies the initial phase of Task WP-2.3.4 Alternative Sodium Recovery Technology, Subtask 1; Develop Near-Tank Nitrate/Nitrite Destruction Technology. Some of the more common anions in carbon steel waste tanks at SRS and Hanford Site are nitrate which is corrosive, and nitrite and hydroxide which are corrosion inhibitors. At present it is necessary to periodically add large quantities of 50 wt% caustic to waste tanks. There are three primary reasons for this addition. First, when the contents of salt tanks are dissolved, sodium hydroxide preferentially dissolves and is removed. During the dissolution process the concentration of free hydroxide in the tank liquid can decrease from 9 M to less than 0.2 M. As a result, roughly half way through the dissolution process large quantities of sodium hydroxide must be added to the tank to comply with requirements for corrosion control. Second, hydroxide is continuously consumed by reaction with carbon dioxide which occurs naturally in purge air used to prevent buildup of hydrogen gas inside the tanks. The hydrogen is generated by radiolysis of water. Third, increasing the concentration of hydroxide increases solubility of some aluminum compounds, which is desirable in processing waste. A process that converts nitrate and nitrite to hydroxide would reduce certain costs. (1) Less caustic would be purchased. (2) Some of the aluminum solid compounds in the waste tanks would become more soluble so less mass of solids would be sent to High Level Vitrification and therefore it would be not be necessary to make as much expensive high level vitrified product. (3) Less mass of sodium would be fed to Saltstone at SRS or Low Level Vitrification at Hanford Site so it would not be necessary to make as much low level product. (4) At SRS less nitrite and nitrate would be sent to Defense Waste Processing Facility (DWPF) so less formic acid would be consumed there and less hydrogen gas would be generated. This task involves

  1. Role of calcium in gravity perception of plant roots

    Science.gov (United States)

    Evans, Michael L.

    1986-01-01

    Calcium ions may play a key role in linking graviperception by the root cap to the asymmetric growth which occurs in the elongation zone of gravistimulated roots. Application of calcium-chelating agents to the root cap inhibits gravitropic curvature without affecting growth. Asymmetric application of calcium to one side of the root cap induces curvature toward the calcium source, and gravistimulation induces polar movement of applied (Ca-45)(2+) across the root cap toward the lower side. The action of calcium may be linked to auxin movement in roots since: (1) auxin transport inhibitors interfere both with gravitropic curvature and graviinduced polar calcium movement and (2) asymmetric application of calcium enhances auxin movement across the elongation zone of gravistimulated roots. Indirect evidence indicates that the calcium-modulated regulator protein, calmodulin, may be involved in either the transport or action of calcium in the gravitropic response mechanism of roots.

  2. Calcium and bones

    Science.gov (United States)

    Bone strength and calcium ... calcium (as well as phosphorus) to make healthy bones. Bones are the main storage site of calcium in ... your body does not absorb enough calcium, your bones can get weak or will not grow properly. ...

  3. Assimilation of nitrate by yeasts.

    Science.gov (United States)

    Siverio, José M

    2002-08-01

    Nitrate assimilation has received much attention in filamentous fungi and plants but not so much in yeasts. Recently the availability of classical genetic and molecular biology tools for the yeast Hansenula polymorpha has allowed the advance of the study of this metabolic pathway in yeasts. The genes YNT1, YNR1 and YNI1, encoding respectively nitrate transport, nitrate reductase and nitrite reductase, have been cloned, as well as two other genes encoding transcriptional regulatory factors. All these genes lie closely together in a cluster. Transcriptional regulation is the main regulatory mechanism that controls the levels of the enzymes involved in nitrate metabolism although other mechanisms may also be operative. The process involved in the sensing and signalling of the presence of nitrate in the medium is not well understood. In this article the current state of the studies of nitrate assimilation in yeasts as well as possible venues for future research are reviewed.

  4. Calcium Test

    Science.gov (United States)

    ... if a person has symptoms of a parathyroid disorder , malabsorption , or an overactive thyroid. A total calcium level is often measured as part of a routine health screening. It is included in the comprehensive metabolic panel (CMP) and the basic metabolic panel (BMP) , ...

  5. Calcium Carbonate

    Science.gov (United States)

    ... doctor if you have or have ever had kidney disease or stomach conditions.tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking calcium carbonate, call your doctor.

  6. Clinical events in high-risk hypertensive patients randomly assigned to calcium channel blocker versus angiotensin-converting enzyme inhibitor in the antihypertensive and lipid-lowering treatment to prevent heart attack trial.

    Science.gov (United States)

    Leenen, Frans H H; Nwachuku, Chuke E; Black, Henry R; Cushman, William C; Davis, Barry R; Simpson, Lara M; Alderman, Michael H; Atlas, Steven A; Basile, Jan N; Cuyjet, Aloysius B; Dart, Richard; Felicetta, James V; Grimm, Richard H; Haywood, L Julian; Jafri, Syed Z A; Proschan, Michael A; Thadani, Udho; Whelton, Paul K; Wright, Jackson T

    2006-09-01

    The Antihypertensive and Lipid-Lowering treatment to prevent Heart Attack Trial (ALLHAT) provides a unique opportunity to compare the long-term relative safety and efficacy of angiotensin-converting enzyme inhibitor and calcium channel blocker-initiated therapy in older hypertensive individuals. Patients were randomized to amlodipine (n=9048) or lisinopril (n=9054). The primary outcome was combined fatal coronary heart disease or nonfatal myocardial infarction, analyzed by intention-to-treat. Secondary outcomes included all-cause mortality, stroke, combined cardiovascular disease (CVD), end-stage renal disease (ESRD), cancer, and gastrointestinal bleeding. Mean follow-up was 4.9 years. Blood pressure control was similar in nonblacks, but not in blacks. No significant differences were found between treatment groups for the primary outcome, all-cause mortality, ESRD, or cancer. Stroke rates were higher on lisinopril in blacks (RR=1.51, 95% CI 1.22 to 1.86) but not in nonblacks (RR=1.07, 95% CI 0.89 to 1.28), and in women (RR=1.45, 95% CI 1.17 to 1.79), but not in men (RR=1.10, 95% CI 0.92 to 1.31). Rates of combined CVD were higher (RR=1.06, 95% CI 1.00 to 1.12) because of higher rates for strokes, peripheral arterial disease, and angina, which were partly offset by lower rates for heart failure (RR=0.87, 95% CI 0.78 to 0.96) on lisinopril compared with amlodipine. Gastrointestinal bleeds and angioedema were higher on lisinopril. Patients with and without baseline coronary heart disease showed similar outcome patterns. We conclude that in hypertensive patients, the risks for coronary events are similar, but for stroke, combined CVD, gastrointestinal bleeding, and angioedema are higher and for heart failure are lower for lisinopril-based compared with amlodipine-based therapy. Some, but not all, of these differences may be explained by less effective blood pressure control in the lisinopril arm.

  7. The calcium-alkali syndrome

    OpenAIRE

    Arroyo, Mariangeli; Fenves, Andrew Z.; Emmett, Michael

    2013-01-01

    The milk-alkali syndrome was a common cause of hypercalcemia, metabolic alkalosis, and renal failure in the early 20th century. It was caused by the ingestion of large quantities of milk and absorbable alkali to treat peptic ulcer disease. The syndrome virtually vanished after introduction of histamine-2 blockers and proton pump inhibitors. More recently, a similar condition called the calcium-alkali syndrome has emerged as a common cause of hypercalcemia and alkalosis. It is usually caused b...

  8. Kinetics of Leaching Calcium from Dolomite

    Directory of Open Access Journals (Sweden)

    Azizi, A.

    2011-06-01

    Full Text Available Magnesia is obtained from magnesite ore and the production process applied should remove accompanying minerals that reduce its refractoriness. Given that magnesite reservoirs are more exploited and largely exhausted, there is a growing need for production of magnesia on the basis of other magnesium minerals. Dolomite is a promising source of magnesia because it forms large deposits, is easy to exploit, and generally contains a small quantity of impurities.The kinetics of calcium leaching from dolomite by magnesium-nitrate solution has been studied. The research program included the influence of temperature, mass fraction of magnesium nitrate in solution, dolomite particle size and leaching time. Time dependence of calcium leaching is described by relevant kinetic equations. Rate coefficients, their temperature dependence and Arrhenius activation energy have been determined.

  9. Effectiveness of inhibitors in increasing chloride threshold value for steel corrosion

    OpenAIRE

    Jin-xia XU; Jiang, Lin-Hua; Wei-lun WANG; TANG, Li; Cui, Li

    2013-01-01

    This investigation was aimed at evaluating the effectiveness of corrosion inhibitors in increasing the chloride threshold value for steel corrosion. Three types of corrosion inhibitors, calcium nitrite (Ca(NO2)2), zinc oxide (ZnO), and N,N'-dimethylaminoethanol (DMEA), which respectively represented the anodic inhibitor, cathodic inhibitor, and mixed inhibitor, were chosen. The experiment was carried out in a saturated calcium hydroxide (Ca(OH)2) solution to simulate the electrolytic environm...

  10. Nitrate storage and dissimilatory nitrate reduction by eukaryotic microbes

    DEFF Research Database (Denmark)

    Kamp, Anja; Høgslund, Signe; Risgaard-Petersen, Nils;

    2015-01-01

    The microbial nitrogen cycle is one of the most complex and environmentally important element cycles on Earth and has long been thought to be mediated exclusively by prokaryotic microbes. Rather recently, it was discovered that certain eukaryotic microbes are able to store nitrate intracellularly...... and use it for dissimilatory nitrate reduction in the absence of oxygen. The paradigm shift that this entailed is ecologically significant because the eukaryotes in question comprise global players like diatoms, foraminifers, and fungi. This review article provides an unprecedented overview of nitrate...... storage and dissimilatory nitrate reduction by diverse marine eukaryotes placed into an eco-physiological context. The advantage of intracellular nitrate storage for anaerobic energy conservation in oxygen-depleted habitats is explained and the life style enabled by this metabolic trait is described...

  11. [Calcium and vitamin D in osteology].

    Science.gov (United States)

    Amling, M; Barvencik, F

    2015-06-01

    Calcium homeostasis is of paramount physiological and pathophysiological importance in health and disease. This article focuses on the skeletal relevance of calcium and vitamin D in daily clinical practice. Against the background of an endemic vitamin D deficiency in Germany and the increasing number of patients with drug-induced (proton pump inhibitor) enteral calcium uptake problems, it is of critical importance to understand that a vitamin D level of > 30 µg/l (> 75 nmol/l) is required for intact skeletal mineralization and that furthermore, a physiological gastric acid production is essential for a normal enteral uptake of calcium from foodstuffs. Therefore, a guideline-conform handling of vitamin D and calcium substitution is required not only for patients with rheumatoid diseases but also for any osteological therapy.

  12. Nitration of Polystyrene-Part II Effect of Nitrating Medium on Nitration

    Directory of Open Access Journals (Sweden)

    I. Bajaj

    1968-04-01

    Full Text Available Polystyrene has been nitrated in mixtures of anhydrous nitric and sulphuric acid (70 : 30 and 80 : 20 by volume. Degree of substitution of nitro group per benzene ring varies from 1 to 2 depending on the time, temperature and composition of the nitrating media. Effect of polar and non polar solvents on nitration has been studied by nitrating the polymer in (i fuming nitric acid and (iimixture of nitric and sulphuric acid in presence of dimethyl formamide (DMF and carbon tetrachloride (CCI/Sub4. MF increase the rate of nitration in fuming nitric acid whereas the rate of nitration is lowered in the presence of DMF in the nitrating mixtures. In the case of CCI/Sub4, however, the effect is just the opposite to that observed in DMF. The results have been explained from the mechanism of the formation of 'nitroniumion,NO/Sub2+ in various nitrating media. Degradation of the polymer has been found to be comparatively less in the presence of the organic solvents used in the study.

  13. ANODIC BEHAVIOR OF ALLOY 22 IN HIGH NITRATE BRINES AT TEMPERATURES HIGHER THAN 100C

    Energy Technology Data Exchange (ETDEWEB)

    G.O. LLEVBARE; J.C. ESTILL; A. YILMAZ; R.A. ETIEN; G.A. HUST M.L. STUART

    2006-04-20

    Alloy 22 (N06022) may be susceptible to crevice corrosion in chloride solutions. Nitrate acts as an inhibitor to crevice corrosion. Several papers have been published regarding the effect of nitrate on the corrosion resistance of Alloy 22 at temperatures 100 C and lower. However, very little is known about the behavior of this alloy in highly concentrated brines at temperatures above 100 C. In the current work, electrochemical tests have been carried out to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 160 C at ambient atmospheres. Even though Alloy 22 may adopt corrosion potentials in the order of +0.5 V (in the saturated silver chloride scale), it does not suffer crevice corrosion if there is high nitrate in the solution. That is, the inhibitive effect of nitrate on crevice corrosion is active for temperatures higher than 100 C.

  14. ACE INHIBITORS: A COMPREHENSIVE REVIEW

    Directory of Open Access Journals (Sweden)

    Pradeep Kumar Arora* and Ashish Chauhan

    2013-02-01

    Full Text Available Hypertension is a chronic increase in blood pressure, characterized as primary and secondary hypertension. The disorder is associated with various risk factors like obesity, diabetes, age, lack of exercise etc. Hypertension is being treated since ancient times by Ayurvedic, Chinese and Unani medicine. Now various allopathic drugs are available which include diuretics, calcium channel blockers, α-blockers, β-blockers, vasodilators, central sympatholytics and ACE-inhibitors. Non-pharmacological treatments include weight reduction, dietary sodium reduction, increased potassium intake and reduction in alcohol consumption. ACE-inhibitors are widely used in the treatment of hypertension by inhibiting the angiotensin converting enzyme responsible for the conversion of angiotensin I to angiotensin II (responsible for vasoconstriction. Various structure activity relationship studies led to the synthesis of ACE-inhibitors, some are under clinical development. This comprehensive review gives various guidelines on classification of hypertension, hypertension therapy including ancient, pharmacological, non-pharmacological therapies, pharmacoeconomics, historical perspectives of ACE, renin, renin angiotensin system (circulating vs local RAS, mechanism of ACE inhibitors, and development of ACE inhibitors. Review also emphasizes on the recent advancements on ACE inhibitors including drugs in clinical trials, computational studies on ACE-inhibitors, peptidomimetics, dual, natural, multi-functional ACE inhibitors, and conformational requirements for ACE-inhibitors.

  15. Avaliação de doses e épocas de aplicação de nitrato de cálcio em cobertura na cultura do rabanete Evaluation of calcium nitrate level and timing of top-dressing in radish

    Directory of Open Access Journals (Sweden)

    Antonio Ismael Inácio Cardoso

    2001-11-01

    Full Text Available Este experimento foi realizado para avaliar o efeito de doses e épocas de aplicação de nitrogênio em cobertura na cultura do rabanete (cultivar Redondo Vermelho. Foram avaliados sete tratamentos com cinco repetições e parcelas com 1,2 m x 0,8 m (espaçamento de 20 cm x 5 cm, no delineamento experimental em blocos ao acaso. Os tratamentos resultaram da combinação dos fatores época da adubação em cobertura [9 e 20 dias após a semeadura (DAS] e doses de nitrogênio (100; 200 e 300 kg/ha na forma de nitrato de cálcio, além da testemunha, sem adubação em cobertura. Em geral, a época de aplicação foi mais importante que o nível de N em cobertura. Quando a adubação foi realizada 9 DAS obteve-se uma produção de 10,30 t/ha de folhas, 10,6 t/ha de raízes (total e 6,20 t/ha de raízes comerciais, superior à adubação realizada aos 20 DAS (7,7 t/ha, 5,8 t/ha e 2,7 t/ha de folhas, raízes totais e raízes comerciais, respectivamente. Quanto às doses de N, a produção de raízes comerciais foi superior com 300 kg/ha (5,1 t/ha em comparação a 100 kg/ha (3,6 t/ha. Para as condições em que foi realizado este experimento, as maiores produções de raízes comerciais foram obtidas com 200 ou 300 kg/ha de N, aplicados 9 DAS, recomendando-se 200 kg/ha pelo menor gasto com este insumo.This trial was set out to evaluate the effect of levels and timing of top-dressing with calcium nitrate in radish (cv Redondo Vermelho. Seven treatments [resulted of the combination of two factors: timing of top-dressing (9 and 20 days after sowing-DAS and N level (100; 200 and 300 kg/ha, besides a standard without top-dressing] were evaluated in a randomized complete block design, with five replicates and plots with 1.2 m x 0.8 m. In general, timing of top-dressing was more important than N levels. When fertilization was made 9 DAS shoot yield was 10.3 t/ha, total root yield was 10.6 t/ha and commercial root yield was 6.2 t/ha, superior to fertilization

  16. Corrosion inhibitors for solar-heating and cooling

    Science.gov (United States)

    Humphries, T. S.

    1979-01-01

    Report describes results of tests conducted to evaluate abilities of 12 candidate corrosion inhibitors to protect aluminum, steel, copper, or stainless steel at typical conditions encountered in solar heating and cooling systems. Inhibitors are based on sodium salts including nitrates, borates, silicates, and phosphates.

  17. Nitrate Reductase: Properties and Regulation

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Nitrate Reductase (NR) is a rating-limit and key enzyme of nitrate assimilation in plants ,so ,NR activity is important for growth,development and the dry matter accumulation of plants. The regulation of NR activity appears to be rather complex and many studies have been devoted to the description of regulation and properties,but in this paper we focus on the properties and regulation of NR in higher plants.

  18. 21 CFR 172.170 - Sodium nitrate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrate. 172.170 Section 172.170 Food and... Preservatives § 172.170 Sodium nitrate. The food additive sodium nitrate may be safely used in or on specified... sablefish, smoked, cured salmon, and smoked, cured shad, so that the level of sodium nitrate does not...

  19. Nitrate transport and signalling.

    Science.gov (United States)

    Miller, Anthony J; Fan, Xiaorong; Orsel, Mathilde; Smith, Susan J; Wells, Darren M

    2007-01-01

    Physiological measurements of nitrate (NO(3)(-)) uptake by roots have defined two systems of high and low affinity uptake. In Arabidopsis, genes encoding both of these two uptake systems have been identified. Most is known about the high affinity transport system (HATS) and its regulation and yet measurements of soil NO(3)(-) show that it is more often available in the low affinity range above 1 mM concentration. Several different regulatory mechanisms have been identified for AtNRT2.1, one of the membrane transporters encoding HATS; these include feedback regulation of expression, a second component protein requirement for membrane targeting and phosphorylation, possibly leading to degradation of the protein. These various changes in the protein may be important for a second function in sensing NO(3)(-) availability at the surface of the root. Another transporter protein, AtNRT1.1 also has a role in NO(3)(-) sensing that, like AtNRT2.1, is independent of their transport function. From the range of concentrations present in the soil it is proposed that the NO(3)(-)-inducible part of HATS functions chiefly as a sensor for root NO(3)(-) availability. Two other key NO(3)(-) transport steps for efficient nitrogen use by crops, efflux across membranes and vacuolar storage and remobilization, are discussed. Genes encoding vacuolar transporters have been isolated and these are important for manipulating storage pools in crops, but the efflux system is yet to be identified. Consideration is given to how well our molecular and physiological knowledge can be integrated as well to some key questions and opportunities for the future.

  20. Treatment of calcium nephrolithiasis in the patient with hyperuricosuria.

    Science.gov (United States)

    Arowojolu, Omotayo; Goldfarb, David S

    2014-12-01

    Nearly one-third of patients with calcium stones have hyperuricosuria. In vitro studies and clinical trials have investigated the relationship between uric acid and calcium stones, but the association between hyperuricosuria and calcium stone formation in patients is still being debated. Uric acid appears to cause salting out of calcium oxalate in human urine. However, the importance of this in vitro phenomenon to the proposed association is not supported in cross-sectional observational studies. A small placebo-controlled randomized clinical trial showed that allopurinol decreased the rate of recurrent calcium oxalate calculi in patients with hyperuricosuria and normocalciuria. An assessment of the effect of combination therapy of allopurinol with indapamide showed no additive effect. Allopurinol may have antioxidant effects that are responsible for its reducing calcium stone formation, which are independent of xanthine oxidase inhibition. In addition, a newer xanthine oxidoreductase inhibitor, febuxostat, may also be effective in the prevention of calcium stones, as it reduces urinary uric acid excretion.

  1. The physiological role of mitochondrial calcium revealed by mice lacking the mitochondrial calcium uniporter.

    Science.gov (United States)

    Pan, Xin; Liu, Jie; Nguyen, Tiffany; Liu, Chengyu; Sun, Junhui; Teng, Yanjie; Fergusson, Maria M; Rovira, Ilsa I; Allen, Michele; Springer, Danielle A; Aponte, Angel M; Gucek, Marjan; Balaban, Robert S; Murphy, Elizabeth; Finkel, Toren

    2013-12-01

    Mitochondrial calcium has been postulated to regulate a wide range of processes from bioenergetics to cell death. Here, we characterize a mouse model that lacks expression of the recently discovered mitochondrial calcium uniporter (MCU). Mitochondria derived from MCU(-/-) mice have no apparent capacity to rapidly uptake calcium. Whereas basal metabolism seems unaffected, the skeletal muscle of MCU(-/-) mice exhibited alterations in the phosphorylation and activity of pyruvate dehydrogenase. In addition, MCU(-/-) mice exhibited marked impairment in their ability to perform strenuous work. We further show that mitochondria from MCU(-/-) mice lacked evidence for calcium-induced permeability transition pore (PTP) opening. The lack of PTP opening does not seem to protect MCU(-/-) cells and tissues from cell death, although MCU(-/-) hearts fail to respond to the PTP inhibitor cyclosporin A. Taken together, these results clarify how acute alterations in mitochondrial matrix calcium can regulate mammalian physiology.

  2. Regulation of BMP2-induced intracellular calcium increases in osteoblasts.

    Science.gov (United States)

    Xu, Wenfeng; Liu, Bo; Liu, Xue; Chiang, Martin Y M; Li, Bo; Xu, Zichen; Liao, Xiaoling

    2016-10-01

    Although bone morphogenetic protein-2 (BMP2) is a well-characterized regulator that stimulates osteoblast differentiation, little is known about how it regulates intracellular Ca(2+) signaling. In this study, intracellular Ca(2+) concentration ([Ca(2+) ]i ) upon BMP2 application, focal adhesion kinase (FAK) and Src activities were measured in the MC3T3-E1 osteoblast cell line using fluorescence resonance energy transfer-based biosensors. Increase in [Ca(2+) ]i , FAK, and Src activities were observed during BMP2 stimulation. The removal of extracellular calcium, the application of membrane channel inhibitors streptomycin or nifedipine, the FAK inhibitor PF-573228 (PF228), and the alkaline phosphatase (ALP) siRNA all blocked the BMP2-stimulated [Ca(2+) ]i increase, while the Src inhibitor PP1 did not. In contrast, a gentle decrease of endoplasmic reticulum calcium concentration was found after BMP2 stimulation, which could be blocked by both streptomycin and PP1. Further experiments revealed that BMP2-induced FAK activation could not be inhibited by PP1, ALP siRNA or the calcium channel inhibitor nifedipine. PF228, but not PP1 or calcium channel inhibitors, suppressed ALP elevation resulting from BMP2 stimulation. Therefore, our results suggest that BMP2 can increase [Ca(2+) ]i through extracellular calcium influx regulated by FAK and ALP and can deplete ER calcium through Src signaling simultaneously. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1725-1733, 2016.

  3. NITRATE DESTRUCTION LITERATURE SURVEY AND EVALUATION CRITERIA

    Energy Technology Data Exchange (ETDEWEB)

    Steimke, J.

    2011-02-01

    This report satisfies the initial phase of Task WP-2.3.4 Alternative Sodium Recovery Technology, Subtask 1; Develop Near-Tank Nitrate/Nitrite Destruction Technology. Some of the more common anions in carbon steel waste tanks at SRS and Hanford Site are nitrate which is corrosive, and nitrite and hydroxide which are corrosion inhibitors. At present it is necessary to periodically add large quantities of 50 wt% caustic to waste tanks. There are three primary reasons for this addition. First, when the contents of salt tanks are dissolved, sodium hydroxide preferentially dissolves and is removed. During the dissolution process the concentration of free hydroxide in the tank liquid can decrease from 9 M to less than 0.2 M. As a result, roughly half way through the dissolution process large quantities of sodium hydroxide must be added to the tank to comply with requirements for corrosion control. Second, hydroxide is continuously consumed by reaction with carbon dioxide which occurs naturally in purge air used to prevent buildup of hydrogen gas inside the tanks. The hydrogen is generated by radiolysis of water. Third, increasing the concentration of hydroxide increases solubility of some aluminum compounds, which is desirable in processing waste. A process that converts nitrate and nitrite to hydroxide would reduce certain costs. (1) Less caustic would be purchased. (2) Some of the aluminum solid compounds in the waste tanks would become more soluble so less mass of solids would be sent to High Level Vitrification and therefore it would be not be necessary to make as much expensive high level vitrified product. (3) Less mass of sodium would be fed to Saltstone at SRS or Low Level Vitrification at Hanford Site so it would not be necessary to make as much low level product. (4) At SRS less nitrite and nitrate would be sent to Defense Waste Processing Facility (DWPF) so less formic acid would be consumed there and less hydrogen gas would be generated. This task involves

  4. Calcium and Vitamin D

    Science.gov (United States)

    ... Cart Home › Patients › Treatment › Calcium/Vitamin D Calcium/Vitamin D Getting enough calcium and vitamin D is ... the-counter medications and calcium supplements. What is Vitamin D and What Does it Do? Vitamin D ...

  5. Imaging calcium in neurons.

    Science.gov (United States)

    Grienberger, Christine; Konnerth, Arthur

    2012-03-08

    Calcium ions generate versatile intracellular signals that control key functions in all types of neurons. Imaging calcium in neurons is particularly important because calcium signals exert their highly specific functions in well-defined cellular subcompartments. In this Primer, we briefly review the general mechanisms of neuronal calcium signaling. We then introduce the calcium imaging devices, including confocal and two-photon microscopy as well as miniaturized devices that are used in freely moving animals. We provide an overview of the classical chemical fluorescent calcium indicators and of the protein-based genetically encoded calcium indicators. Using application examples, we introduce new developments in the field, such as calcium imaging in awake, behaving animals and the use of calcium imaging for mapping single spine sensory inputs in cortical neurons in vivo. We conclude by providing an outlook on the prospects of calcium imaging for the analysis of neuronal signaling and plasticity in various animal models.

  6. Phosphocitrate inhibits mitochondrial and cytosolic accumulation of calcium in kidney cells in vivo.

    OpenAIRE

    Tew, W. P.; Malis, C D; Howard, J. E.; Lehninger, A L

    1981-01-01

    Synthetic 3-phosphocitrate, an extremely potent inhibitor of calcium phosphate crystallization as determined in a nonbiological physical-chemical assay, has many similarities to a mitochondrial factor that inhibits crystallization of nondiffracting amorphous calcium phosphate. In order to determine whether phosphocitrate can prevent uptake and crystallization of calcium phosphate in mitochondria in vivo, it was administered intraperitoneally to animals given large daily doses of calcium gluco...

  7. COOH-terminal association of human smooth muscle calcium channel Ca(v)1.2b with Src kinase protein binding domains: effect of nitrotyrosylation.

    Science.gov (United States)

    Kang, Minho; Ross, Gracious R; Akbarali, Hamid I

    2007-12-01

    The carboxyl terminus of the calcium channel plays an important role in the regulation of calcium entry, signal transduction, and gene expression. Potential protein-protein interaction sites within the COOH terminus of the L-type calcium channel include those for the SH3 and SH2 binding domains of c-Src kinase that regulates calcium currents in smooth muscle. In this study, we examined the binding sites involved in Src kinase-mediated phosphorylation of the human voltage-gated calcium channel (Ca(v)) 1.2b (hCav1.2b) and the effect of nitrotyrosylation. Cotransfection of human embryonic kidney (HEK)-293 cells with hCa(v)1.2b and c-Src resulted in tyrosine phosphorylation of the calcium channel, which was prevented by nitration of tyrosine residues by peroxynitrite. Whole cell calcium currents were reduced by 58 + 5% by the Src kinase inhibitor PP2 and 64 + 6% by peroxynitrite. Nitrotyrosylation prevented Src-mediated regulation of the currents. Glutathione S-transferase fusion protein of the distal COOH terminus of hCa(v)1.2b (1809-2138) bound to SH2 domain of Src following tyrosine phosphorylation, while binding to SH3 required the presence of the proline-rich motif. Site-directed mutation of Y(2134) prevented SH2 binding and resulted in reduced phosphorylation of hCa(v)1.2b. Within the distal COOH terminus, single, double, or triple mutations of Y(1837), Y(1861), and Y(2134) were constructed and expressed in HEK-293 cells. The inhibitory effects of PP2 and peroxynitrite on calcium currents were significantly reduced in the double mutant Y(1837-2134F). These data demonstrate that the COOH terminus of hCa(v)1.2b contains sites for the SH2 and SH3 binding of Src kinase. Nitrotyrosylation of these sites prevents Src kinase regulation and may be importantly involved in calcium influx regulation during inflammation.

  8. The putative P-gp inhibitor telmisartan does not affect the transcellular permeability and cellular uptake of the calcium channel antagonist verapamil in the P-glycoprotein expressing cell line MDCK II MDR1

    DEFF Research Database (Denmark)

    Saaby, Lasse; Tfelt-Hansen, Peer; Brodin, Birger

    2015-01-01

    Verapamil is used in high doses for the treatment of cluster headache. Verapamil has been described as a P-glycoprotein (P-gp, ABCB1) substrate. We wished to evaluate in vitro whether co administration of a P-gp inhibitor with verapamil could be a feasible strategy for increasing CNS uptake...

  9. The putative P-gp inhibitor telmisartan does not affect the transcellular permeability and cellular uptake of the calcium channel antagonist verapamil in the P-glycoprotein expressing cell line MDCK II MDR1.

    Science.gov (United States)

    Saaby, Lasse; Tfelt-Hansen, Peer; Brodin, Birger

    2015-08-01

    Verapamil is used in high doses for the treatment of cluster headache. Verapamil has been described as a P-glycoprotein (P-gp, ABCB1) substrate. We wished to evaluate in vitro whether co administration of a P-gp inhibitor with verapamil could be a feasible strategy for increasing CNS uptake of verapamil. Fluxes of radiolabelled verapamil across MDCK II MDR1 monolayers were measured in the absence and presence of the putative P-gp inhibitor telmisartan (a clinically approved drug compound). Verapamil displayed a vectorial basolateral-to-apical transepithelial efflux across the MDCK II MDR1 monolayers with a permeability of 5.7 × 10(-5) cm sec(-1) compared to an apical to basolateral permeability of 1.3 × 10(-5) cm sec(-1). The efflux could be inhibited with the P-gp inhibitor zosuquidar. Zosuquidar (0.4 μmol/L) reduced the efflux ratio (PB-A/PA-B) for verapamil 4.6-1.6. The presence of telmisartan, however, only caused a slight reduction in P-gp-mediated verapamil transport to an efflux ratio of 3.4. Overall, the results of the present in vitro approach indicate, that clinical use of telmisartan as a P-gp inhibitor may not be an effective strategy for increasing brain uptake of verapamil by co-administration with telmisartan.

  10. The effect of nitrate on ethylene biofiltration

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang-Hun, E-mail: lee323@alumni.purdue.edu [Department of Agricultural and Biological Engineering, Purdue University, 225 South University St., West Lafayette, 47907-2093 IN (United States); Li, Congna; Heber, Albert J. [Department of Agricultural and Biological Engineering, Purdue University, 225 South University St., West Lafayette, 47907-2093 IN (United States)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer Ethylene biofiltration strongly depends on nitrate concentrations and media types. Black-Right-Pointing-Pointer We examine reduced N supply can increase ethylene removals in biofilters. Black-Right-Pointing-Pointer Perlite medium is better for ethylene biofiltration than activated carbon medium. - Abstract: This study investigated the effects of filter media types and nitrate (NO{sub 3}{sup -}) concentrations in nutrient solutions on C{sub 2}H{sub 4} biofiltration. A new nutrient solution with zero NO{sub 3}{sup -} concentration was supplied to two perlite-bed biotrickling filters, two perlite-bed biofilters, and two GAC (Granular Activated Carbon)-bed biofilters, while the other with 2 g L{sup -1} of NO{sub 3}{sup -} was used for the other two GAC biofilters. All reactors underwent a total test duration of over 175 days with an EBRT (Empty Bed Residence Time) of 30 s, inlet gas flow rate of 7 L min{sup -1}, and inlet C{sub 2}H{sub 4} concentrations of 20-30 mg m{sup -3}. NO{sub 3}{sup -} concentration and media type significantly affected the C{sub 2}H{sub 4} removal efficiencies in all types of biofiltration. The perlite media with no NO{sub 3}{sup -} achieved C{sub 2}H{sub 4} removal efficiencies 10-50% higher than the others. A NO{sub 3}{sup -} concentration as high as 2 g L{sup -1} in the original nutrient solution may act as an inhibitor that suppresses the growth or activity of C{sub 2}H{sub 4} degraders. In addition, the perlite media resulted in higher C{sub 2}H{sub 4} removal efficiencies than GAC media, because the hydrophilic surface of the perlite leads to a higher moisture content and thus to favorable microbial growth.

  11. Short-term effects of a high nitrate diet on nitrate metabolism in healthy individuals.

    Science.gov (United States)

    Bondonno, Catherine P; Liu, Alex H; Croft, Kevin D; Ward, Natalie C; Puddey, Ian B; Woodman, Richard J; Hodgson, Jonathan M

    2015-03-12

    Dietary nitrate, through the enterosalivary nitrate-nitrite-NO pathway, can improve blood pressure and arterial stiffness. How long systemic nitrate and nitrite remain elevated following cessation of high nitrate intake is unknown. In 19 healthy men and women, the time for salivary and plasma nitrate and nitrite to return to baseline after 7 days increased nitrate intake from green leafy vegetables was determined. Salivary and plasma nitrate and nitrite was measured at baseline [D0], end of high nitrate diet [D7], day 9 [+2D], day 14 [+7D] and day 21 [+14D]. Urinary nitrite and nitrate was assessed at D7 and +14D. Increased dietary nitrate for 7 days resulted in a more than fourfold increase in saliva and plasma nitrate and nitrite (p nitrate had returned to baseline while saliva nitrate and nitrite were more than 1.5 times higher than at baseline levels. By [+7D] all metabolites had returned to baseline levels. The pattern of response was similar between men and women. Urinary nitrate and nitrate was sevenfold higher at D7 compared to +14D. These results suggest that daily ingestion of nitrate may be required to maintain the physiological changes associated with high nitrate intake.

  12. Synthesis and Formation Mechanisms of Calcium Ferrite Compounds

    Institute of Scientific and Technical Information of China (English)

    Hesham I. Saleh

    2004-01-01

    Calcium ferrite compounds were prepared using calcium nitrate and iron nitrate with different molar ratios, 1:1, 0.5:1, and 1:0.5,respectively. The reactions of formation were investigated at different temperatures following the differential thermal analysis (DTA) results. Calcium ferrite compounds are CaFeO3, Ca2FeO3.5, Ca2Fe2O5, CaFe2O4, CaFe4O7, Ca7.2Fe0.8Fe30O53,Ca3Fe15O25, Ca4Fe14O25, and Ca4Fe9O17. Other reactive species of calcium nitrate are still present after firing at 450℃.Compounds were characterized using X-ray diffraction (XRD), DTA, TG, magnetic susceptibility, infrared spectra and scanning electron microscope (SEM). It is concluded that the formation mechanism of Ca-ferrite compounds depends mainly on the valency of iron cations which in role depends on its molar ratio and the existing atmosphere.

  13. Efficiency of nitrate uptake in spinach : impact of external nitrate concentration and relative growth rate on nitrate influx and efflux

    NARCIS (Netherlands)

    Ter Steege, MW; Stulen, [No Value; Wiersema, PK; Posthumus, F; Vaalburg, W

    1999-01-01

    Regulation of nitrate influx and efflux in spinach (Spinacia oleracea L., cv. Subito), was studied in short-term label experiments with N-13- and N-15-nitrate. Nitrate fluxes were examined in relation to the N demand for growth, defined as relative growth rate (RGR) times plant N concentration. Plan

  14. Variability of nitrate and phosphate

    Digital Repository Service at National Institute of Oceanography (India)

    Sardessai, S.; Sundar, D.

    elements in the Mandovi and Zuari estuaries, Goa, India. During the month of September in the wet season nitrate concentration in the mid estuarine region of the Mandovi estuary increased from 4.4 mu M in the upstream region to 6.0 mu M. This increase could...

  15. Metal nitrate conversion method, patent application

    NARCIS (Netherlands)

    2008-01-01

    A method for converting a supported metal nitrate into the corresponding supported metal comprises heating the metal nitrate to effect its decomposition under a gas mixture that contains nitric oxide and has an oxygen content of

  16. XPS and GDOES Characterization of Porous Coating Enriched with Copper and Calcium Obtained on Tantalum via Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Krzysztof Rokosz

    2016-01-01

    Full Text Available XPS and GDOES characterizations of porous coatings on tantalum after Plasma Electrolytic Oxidation (PEO at 450 V for 3 minutes in electrolyte containing concentrated (85% phosphoric acid with calcium nitrate and copper (II nitrate are described. Based on the obtained data, it may be concluded that the PEO coating consists of tantalum (Ta5+, calcium (Ca2+, copper (Cu2+  and Cu+, and phosphates (PO43-. It has to be pointed out that copper and calcium are distributed throughout the volume. The authors also propose a new model of PEO, based on the derivative of GDOES signals with sputtering time.

  17. Calcium regulates caveolin-1 expression at the transcriptional level

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiao-Yan; Huang, Cheng-Cheng; Kan, Qi-Ming [Laboratory of Tumor Biology and Glycobiology, Department of Life Sciences, Shenyang Pharmaceutical University, Shenyang 110016, People' s Republic of China (China); Li, Yan [Experimental Animal Center, Department of Life Sciences, Shenyang Pharmaceutical University, Shenyang 110016, People' s Republic of China (China); Liu, Dan; Zhang, Xue-Cheng [Laboratory of Tumor Biology and Glycobiology, Department of Life Sciences, Shenyang Pharmaceutical University, Shenyang 110016, People' s Republic of China (China); Sato, Toshinori [Department of Biosciences and Informatics, Keio University, Hiyoshi, Yokohama 223-8522 (Japan); Yamagata, Sadako [Laboratory of Tumor Biology and Glycobiology, Department of Life Sciences, Shenyang Pharmaceutical University, Shenyang 110016, People' s Republic of China (China); Yamagata, Tatsuya, E-mail: tcyamagata@gmail.com [Laboratory of Tumor Biology and Glycobiology, Department of Life Sciences, Shenyang Pharmaceutical University, Shenyang 110016, People' s Republic of China (China)

    2012-09-28

    Highlights: Black-Right-Pointing-Pointer Caveolin-1 expression is regulated by calcium signaling at the transcriptional level. Black-Right-Pointing-Pointer An inhibitor of or siRNA to L-type calcium channel suppressed caveolin-1 expression. Black-Right-Pointing-Pointer Cyclosporine A or an NFAT inhibitor markedly reduced caveolin-1 expression. Black-Right-Pointing-Pointer Caveolin-1 regulation by calcium signaling is observed in several mouse cell lines. -- Abstract: Caveolin-1, an indispensable component of caveolae serving as a transformation suppressor protein, is highly expressed in poorly metastatic mouse osteosarcoma FBJ-S1 cells while highly metastatic FBJ-LL cells express low levels of caveolin-1. Calcium concentration is higher in FBJ-S1 cells than in FBJ-LL cells; therefore, we investigated the possibility that calcium signaling positively regulates caveolin-1 in mouse FBJ-S1 cells. When cells were treated with the calcium channel blocker nifedipine, cyclosporin A (a calcineurin inhibitor), or INCA-6 (a nuclear factor of activated T-cells [NFAT] inhibitor), caveolin-1 expression at the mRNA and protein levels decreased. RNA silencing of voltage-dependent L-type calcium channel subunit alpha-1C resulted in suppression of caveolin-1 expression. This novel caveolin-1 regulation pathway was also identified in mouse NIH 3T3 cells and Lewis lung carcinoma cells. These results indicate that caveolin-1 is positively regulated at the transcriptional level through a novel calcium signaling pathway mediated by L-type calcium channel/Ca{sup 2+}/calcineurin/NFAT.

  18. Nitrate Removal from Ground Water: A Review

    OpenAIRE

    Archna *; Surinder K. Sharma; Ranbir Chander Sobti

    2012-01-01

    Nitrate contamination of ground water resources has increased in Asia, Europe, United States, and various other parts of the world. This trend has raised concern as nitrates cause methemoglobinemia and cancer. Several treatment processes can remove nitrates from water with varying degrees of efficiency, cost, and ease of operation. Available technical data, experience, and economics indicate that biological denitrification is more acceptable for nitrate removal than reverse osmosis and ion ex...

  19. Calcium-dependent and calcium-sensitizing pathways in the mature and immature ductus arteriosus.

    Science.gov (United States)

    Clyman, Ronald I; Waleh, Nahid; Kajino, Hiroki; Roman, Christine; Mauray, Francoise

    2007-10-01

    Studies performed in sheep and baboons have shown that after birth, the normoxic muscle media of ductus arteriosus (DA) becomes profoundly hypoxic as it constricts and undergoes anatomic remodeling. We used isolated fetal lamb DA (pretreated with inhibitors of prostaglandin and nitric oxide production) to determine why the immature DA fails to remain tightly constricted during the hypoxic phase of remodeling. Under normoxic conditions, mature DA constricts to 70% of its maximal active tension (MAT). Half of its normoxic tension is due to Ca(2+) entry through calcium L-channels and store-operated calcium (SOC) channels. The other half is independent of extracellular Ca(2+) and is unaffected by inhibitors of sarcoplasmic reticulum (SR) Ca(2+) release (ryanodine) or reuptake [cyclopiazonic acid (CPA)]. The mature DA relaxes slightly during hypoxia (to 60% MAT) due to decreases in calcium L-channel-mediated Ca(2+) entry. Inhibitors of Rho kinase and tyrosine kinase inhibit both Ca(2+)-dependent and Ca(2+)-independent DA tension. Although Rho kinase activity may increase during gestation, immature DA develop lower tensions than mature DA, primarily because of differences in the way they process Ca(2+). Calcium L-channel expression increases with advancing gestation. Under normoxic conditions, differences in calcium L-channel-mediated Ca(2+) entry account for differences in tension between immature (60% MAT) and mature (70% MAT) DA. Under hypoxic conditions, differences in both calcium L-channel-dependent and calcium L-channel-independent Ca(2+) entry, account for differences in tension between immature (33% MAT) and mature (60% MAT) DA. Stimulation of Ca(2+) entry through reverse-mode Na(+)/Ca(2+) exchange or CPA-induced SOC channel activity constrict the DA and eliminate differences between immature and mature DA during both hypoxia and normoxia.

  20. Store-Operated Calcium Channels.

    Science.gov (United States)

    Prakriya, Murali; Lewis, Richard S

    2015-10-01

    Store-operated calcium channels (SOCs) are a major pathway for calcium signaling in virtually all metozoan cells and serve a wide variety of functions ranging from gene expression, motility, and secretion to tissue and organ development and the immune response. SOCs are activated by the depletion of Ca(2+) from the endoplasmic reticulum (ER), triggered physiologically through stimulation of a diverse set of surface receptors. Over 15 years after the first characterization of SOCs through electrophysiology, the identification of the STIM proteins as ER Ca(2+) sensors and the Orai proteins as store-operated channels has enabled rapid progress in understanding the unique mechanism of store-operate calcium entry (SOCE). Depletion of Ca(2+) from the ER causes STIM to accumulate at ER-plasma membrane (PM) junctions where it traps and activates Orai channels diffusing in the closely apposed PM. Mutagenesis studies combined with recent structural insights about STIM and Orai proteins are now beginning to reveal the molecular underpinnings of these choreographic events. This review describes the major experimental advances underlying our current understanding of how ER Ca(2+) depletion is coupled to the activation of SOCs. Particular emphasis is placed on the molecular mechanisms of STIM and Orai activation, Orai channel properties, modulation of STIM and Orai function, pharmacological inhibitors of SOCE, and the functions of STIM and Orai in physiology and disease.

  1. 49 CFR 176.410 - Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Division 1.5 materials, ammonium nitrate and ammonium nitrate mixtures. 176.410 Section 176.410 Transportation Other Regulations Relating to... nitrate and ammonium nitrate mixtures. (a) This section prescribes requirements to be observed...

  2. 76 FR 46907 - Ammonium Nitrate Security Program

    Science.gov (United States)

    2011-08-03

    ... and fertilizer blends containing more than 15% by weight ammonium nitrate, except liquid fertilizers... concerning the detonability of ammonium nitrate; Comments on how likely ammonium nitrate fertilizer users would be to use an alternative fertilizer that is potentially less detonable, such as Sulf-N...

  3. 76 FR 11273 - Ammonium Nitrate From Russia

    Science.gov (United States)

    2011-03-01

    ... COMMISSION Ammonium Nitrate From Russia AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the suspended investigation on ammonium nitrate from Russia... investigation on ammonium nitrate from Russia would be likely to lead to continuation or recurrence of...

  4. 76 FR 47238 - Ammonium Nitrate From Russia

    Science.gov (United States)

    2011-08-04

    ... COMMISSION Ammonium Nitrate From Russia Determination On the basis of the record \\1\\ developed in the subject... order on ammonium nitrate from Russia would be likely to lead to continuation or recurrence of material... Commission are contained in USITC Publication 4249 (August 2011), entitled Ammonium Nitrate from...

  5. 21 CFR 172.160 - Potassium nitrate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium nitrate. 172.160 Section 172.160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Preservatives § 172.160 Potassium nitrate. The food additive potassium nitrate may be safely used as a...

  6. Use of the Time Domain Reflectometry to evaluate the nitrate distribution in fertirrigated soils columns

    Directory of Open Access Journals (Sweden)

    Rubens Alves de Oliveira

    2009-12-01

    Full Text Available The monitoring of spatial and temporal variation of the soil water content (θ, of the soil bulk electric conductivity (CEs, of the soil solution electric conductivity (CEss and of the ion concentration (Ci enables to estimate the water loss by deep percolation and evapotranspiration, to determine the areas of nutrients extraction by plants and the possible nutrients loss by leaching. The of objective this work was to evaluate, using the TDR technique, the nitrate distribution in Typic Quartzipsamment (RQ and Oxisol (LV soil columns fertirrigated with calcium nitrate. Nitrate fertirrigations were accomplished in the columns, and the soil water content (θ and the soil bulk electric conductivity (CEs obtained with TDR. The nitrate concentration was estimated using the values of θ and of CEs. In the RQ soil, the nitrate reached 30, 21 e 12 cm when the fertirrigations were done at the beginning, at the middle and at the end of the irrigation period, respectively. In the LV soil, independently of the moment of the fertirrigation, the nitrate was retained in the layer from 0 to 12 cm deep.

  7. Nitrate Deposition to Surface Snow at Summit, Greenland, Following the 9 November 2000 Solar Proton Event

    Science.gov (United States)

    Duderstadt, Katharine A.; Dibb, Jack E.; Schwadron, Nathan A.; Spence, Harlan E.; Jackman, Charles Herbert; Randall, Cora E.; Solomon, Stanley C.; Mills, Michael J.

    2014-01-01

    This study considers whether spurious peaks in nitrate ions in snow sampled at Summit, Greenland from August 2000 to August 2002 are related to solar proton events. After identifying tropospheric sources of nitrate on the basis of correlations with sulfate, ammonium, sodium, and calcium, we use the three-dimensional global Whole Atmosphere Community Climate Model (WACCM) to examine unaccounted for nitrate spikes. Model calculations confirm that solar proton events significantly impact HOx, NOx, and O3 levels in the mesosphere and stratosphere during the weeks and months following the major 9 November 2000 solar proton event. However, SPE-enhanced NOy calculated within the atmospheric column is too small to account for the observed nitrate ion peaks in surface snow. Instead, our WACCM results suggest that nitrate spikes not readily accounted for by measurement correlations are likely of anthropogenic origin. These results, consistent with other recent studies, imply that nitrate spikes in ice cores are not suitable proxies for individual SPEs and motivate the need to identify alternative proxies.

  8. Analytical Chemistry and Materials Characterization Results for Debris Recovered from Nitrate Salt Waste Drum S855793

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Patrick Thomas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chamberlin, Rebecca M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schwartz, Daniel S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Worley, Christopher Gordon [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Garduno, Katherine [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lujan, Elmer J. W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Borrego, Andres Patricio [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Castro, Alonso [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Colletti, Lisa Michelle [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Fulwyler, James Brent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Holland, Charlotte S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Keller, Russell C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Klundt, Dylan James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martinez, Alexander [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martin, Frances Louise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Montoya, Dennis Patrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Myers, Steven Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Porterfield, Donivan R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schake, Ann Rene [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Schappert, Michael Francis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Soderberg, Constance B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Spencer, Khalil J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Stanley, Floyd E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Thomas, Mariam R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Townsend, Lisa Ellen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Xu, Ning [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-09-16

    Solid debris was recovered from the previously-emptied nitrate salt waste drum S855793. The bulk sample was nondestructively assayed for radionuclides in its as-received condition. Three monoliths were selected for further characterization. Two of the monoliths, designated Specimen 1 and 3, consisted primarily of sodium nitrate and lead nitrate, with smaller amounts of lead nitrate oxalate and lead oxide by powder x-ray diffraction. The third monolith, Specimen 2, had a complex composition; lead carbonate was identified as the predominant component, and smaller amounts of nitrate, nitrite and carbonate salts of lead, magnesium and sodium were also identified. Microfocused x-ray fluorescence (MXRF) mapping showed that lead was ubiquitous throughout the cross-sections of Specimens 1 and 2, while heteroelements such as potassium, calcium, chromium, iron, and nickel were found in localized deposits. MXRF examination and destructive analysis of fragments of Specimen 3 showed elevated concentrations of iron, which were broadly distributed through the sample. With the exception of its high iron content and low carbon content, the chemical composition of Specimen 3 was within the ranges of values previously observed in four other nitrate salt samples recovered from emptied waste drums.

  9. Nitrate tolerance impairs nitric oxide-mediated vasodilation in vivo

    DEFF Research Database (Denmark)

    Laursen, Jørn Bech; Boesgaard, Søren; Poulsen, Henrik E.;

    1996-01-01

    Nitrates, Nitrate tolerence, Nitric oxide, acetylcholine, N-acetylcholine, N-acetylcysteine, L-NAME, Rat, Anesthetized......Nitrates, Nitrate tolerence, Nitric oxide, acetylcholine, N-acetylcholine, N-acetylcysteine, L-NAME, Rat, Anesthetized...

  10. Negative feedback loops leading to nitrate homeostasis and oscillatory nitrate assimilation in plants and fungi.

    OpenAIRE

    Huang, Yongshun

    2011-01-01

    Nitrate is an important nutrient for plants and fungi. For plants it has been shown that cytosolic nitrate levels are under homeostatic control. Here we describe two networks that can obtain robust, i.e. perturbation independent, homeostatic behavior in cytosolic nitrate concentration. One of the networks, a member in the family of outflow controllers, is based on a negative feedback loop containing a nitrate-induced activation of a controller molecule which removes nitrate. In plants this co...

  11. Calcium and Mitosis

    Science.gov (United States)

    Hepler, P.

    1983-01-01

    Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

  12. Continuous flow nitration in miniaturized devices

    Directory of Open Access Journals (Sweden)

    Amol A. Kulkarni

    2014-02-01

    Full Text Available This review highlights the state of the art in the field of continuous flow nitration with miniaturized devices. Although nitration has been one of the oldest and most important unit reactions, the advent of miniaturized devices has paved the way for new opportunities to reconsider the conventional approach for exothermic and selectivity sensitive nitration reactions. Four different approaches to flow nitration with microreactors are presented herein and discussed in view of their advantages, limitations and applicability of the information towards scale-up. Selected recent patents that disclose scale-up methodologies for continuous flow nitration are also briefly reviewed.

  13. Repassivation Potential of Alloy 22 in Sodium and Calcium Chloride Brines

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R B; Ilevbare, G O; Carranza, R M

    2007-08-11

    A comprehensive matrix of 60 tests was designed to explore the effect of calcium chloride vs. sodium chloride and the ratio R of nitrate concentration over chloride concentration on the repassivation potential of Alloy 22. Tests were conducted using the cyclic potentiodynamic polarization (CPP) technique at 75 C and at 90 C. Results show that at a ratio R of 0.18 and higher nitrate was able to inhibit the crevice corrosion in Alloy 22 induced by chloride. Current results fail to show in a consistent way a different effect on the repassivation potential of Alloy 22 for calcium chloride solutions than for sodium chloride solutions.

  14. Nitric Oxide-Mediated Maize Root Apex Responses to Nitrate are Regulated by Auxin and Strigolactones

    Directory of Open Access Journals (Sweden)

    Alessandro eManoli

    2016-01-01

    Full Text Available Nitrate (NO3- is a key element for crop production but its levels in agricultural soils are limited. Plants have developed mechanisms to cope with these NO3- fluctuations based on sensing nitrate at the root apex. Particularly, the transition zone (TZ of root apex has been suggested as a signalling-response zone. This study dissects cellular and molecular mechanisms underlying NO3- resupply effects on primary root growth in maize, confirming nitric oxide (NO as a putative modulator. Nitrate restoration induced primary root elongation within the first 2 h, corresponding to a stimulation of cell elongation at the basal border of the TZ. Xyloglucans (XGs immunolocalization together with Brefeldin A applications demonstrated that nitrate resupply induces XG accumulation. This effect was blocked by cPTIO (NO scavenger. Transcriptional analysis of ZmXET1 confirmed the stimulatory effect of nitrate on XGs accumulation in cells of the TZ. Immunolocalization analyses revealed a positive effect of nitrate resupply on auxin and PIN1 accumulation, but a transcriptional regulation of auxin biosynthesis/transport/signalling genes was excluded. Short-term nitrate treatment repressed the transcription of genes involved in strigolactones (SLs biosynthesis and transport, mainly in the TZ. Enhancement of carotenoid cleavage dioxygenases (CCDs transcription in presence of cPTIO indicated endogenous NO as a negative modulator of CCDs activity. Finally, treatment with the SLs-biosynthesis inhibitor (TIS108 restored the root growth in the nitrate-starved seedlings. Present report suggests that the NO-mediated root apex responses to nitrate are accomplished in cells of the TZ via integrative actions of auxin, NO and SLs.

  15. Nitric Oxide-Mediated Maize Root Apex Responses to Nitrate are Regulated by Auxin and Strigolactones.

    Science.gov (United States)

    Manoli, Alessandro; Trevisan, Sara; Voigt, Boris; Yokawa, Ken; Baluška, František; Quaggiotti, Silvia

    2015-01-01

    Nitrate (NO3 (-)) is a key element for crop production but its levels in agricultural soils are limited. Plants have developed mechanisms to cope with these NO3 (-) fluctuations based on sensing nitrate at the root apex. Particularly, the transition zone (TZ) of root apex has been suggested as a signaling-response zone. This study dissects cellular and molecular mechanisms underlying NO3 (-) resupply effects on primary root (PR) growth in maize, confirming nitric oxide (NO) as a putative modulator. Nitrate restoration induced PR elongation within the first 2 h, corresponding to a stimulation of cell elongation at the basal border of the TZ. Xyloglucans (XGs) immunolocalization together with Brefeldin A applications demonstrated that nitrate resupply induces XG accumulation. This effect was blocked by cPTIO (NO scavenger). Transcriptional analysis of ZmXET1 confirmed the stimulatory effect of nitrate on XGs accumulation in cells of the TZ. Immunolocalization analyses revealed a positive effect of nitrate resupply on auxin and PIN1 accumulation, but a transcriptional regulation of auxin biosynthesis/transport/signaling genes was excluded. Short-term nitrate treatment repressed the transcription of genes involved in strigolactones (SLs) biosynthesis and transport, mainly in the TZ. Enhancement of carotenoid cleavage dioxygenases (CCDs) transcription in presence of cPTIO indicated endogenous NO as a negative modulator of CCDs activity. Finally, treatment with the SLs-biosynthesis inhibitor (TIS108) restored the root growth in the nitrate-starved seedlings. Present report suggests that the NO-mediated root apex responses to nitrate are accomplished in cells of the TZ via integrative actions of auxin, NO and SLs.

  16. Gallium nitrate regulates rat osteoblast expression of osteocalcin protein and mRNA levels.

    Science.gov (United States)

    Guidon, P T; Salvatori, R; Bockman, R S

    1993-01-01

    Gallium nitrate, a group IIIa metal salt, has been found to be clinically effective for the treatment of accelerated bone resorption in cancer-related hypercalcemia and Paget's disease. Here we report the effects of gallium nitrate on osteocalcin mRNA and protein levels on the rat osteoblast-like cell line ROS 17/2.8. Gallium nitrate reduced both constitutive and vitamin D3-stimulated osteocalcin protein levels in culture medium by one-half and osteocalcin mRNA levels to one-third to one-tenth of control. Gallium nitrate also inhibited vitamin D3 stimulation of osteocalcin and osteopontin mRNA levels but did not affect constitutive osteopontin mRNA levels. Among several different metals examined, gallium was unique in its ability to reduce osteocalcin mRNA levels without decreasing levels of other mRNAs synthesized by ROS 17/2.8 cells. The effects of gallium nitrate on osteocalcin mRNA and protein synthesis mimic those seen when ROS 17/2.8 cells are exposed to transforming growth factor beta 1 (TGF beta 1); however, TGF-beta 1 was not detected in gallium nitrate-treated ROS 17/2.8 cell media. Use of the RNA polymerase II inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole demonstrated that gallium nitrate did not alter the stability of osteocalcin mRNA. Transient transfection assays using the rat osteocalcin promoter linked to the bacterial reporter gene chloramphenicol acetyltransferase indicated that gallium nitrate blocked reporter gene expression stimulated by the osteocalcin promoter. This is the first reported effect of gallium nitrate on isolated osteoblast cells.

  17. Calcium involved in the poly(γ-glutamic acid)-mediated promotion of Chinese cabbage nitrogen metabolism.

    Science.gov (United States)

    Xu, Zongqi; Lei, Peng; Feng, Xiaohai; Xu, Xianju; Liang, Jinfeng; Chi, Bo; Xu, Hong

    2014-07-01

    Plant growth can reportedly be promoted by poly(γ-glutamic acid) (γ-PGA). However, the underlying mechanism is unknown. To reveal the mechanism of γ-PGA, we designed an experiment that investigated the effect of γ-PGA on the nitrogen metabolism of Chinese cabbage hydroponic cultured at different calcium (Ca) levels and varied exogenous Ca(2+) inhibitors. The results showed that nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase, and glutamate dehydrogenase activities in leaves and roots were obviously enhanced by γ-PGA at the normal Ca(2+) level (4.0 mM). Meanwhile, γ-PGA increased the content of total nitrogen, soluble protein, and soluble amino acids in leaves. However, the promotional effect of γ-PGA on fresh weight weakened when Ca(2+) was inadequate. Moreover, γ-PGA not only induced the influx of extracellular Ca(2+) and Ca(2+) in organelles into cytoplasm, but also increased the Ca(2+)-ATPase level to modify Ca(2+) homeostasis in plant cells. In addition, exogenous Ca(2+) inhibitors significantly suppressed the γ-PGA-mediated promotion of cytoplasmic free Ca(2+) level, calmodulin (CaM) content, GS and glutamate dehydrogenase activities. In summary, γ-PGA accelerated the nitrogen metabolism of plants through the Ca(2+)/CaM signaling pathway, thereby improving the growth of the plant.

  18. Phase diagram of ammonium nitrate

    Science.gov (United States)

    Dunuwille, M.; Yoo, C. S.

    2014-05-01

    Ammonium Nitrate (AN) has often subjected to uses in improvised explosive devices, due to its wide availability as a fertilizer and its capability of becoming explosive with slight additions of organic and inorganic compounds. Yet, the origin of enhanced energetic properties of impure AN (or AN mixtures) is neither chemically unique nor well understood -resulting in rather catastrophic disasters in the past1 and thereby a significant burden on safety in using ammonium nitrates even today. To remedy this situation, we have carried out an extensive study to investigate the phase stability of AN at high pressure and temperature, using diamond anvil cells and micro-Raman spectroscopy. The present results confirm the recently proposed phase IV-to-IV' transition above 17 GPa2 and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400 °C.

  19. Nitrate metabolism in the gromiid microbial universe

    DEFF Research Database (Denmark)

    Høgslund, Signe; Risgaard-Petersen, Nils; Cedhagen, Tomas

    Eukaryotic nitrate respiration supported by intracellular nitrate storages contributes substantially to the nitrogen cycle. Research focus is currently directed towards two phyla: Foraminifera and diatoms, but the widespread Gromia in the Rhizaria may be another key organism. These giant protists...... enclose and regulate a small biogeochemical universe within their cell. Their transparent proteinaceous cell wall surrounds a complex matrix consisting of sediment, bacteria and nitrate which is concentrated to hundreds of mM in the gromiid cell. The nitrate is respired to dinitrogen, but in contrast...... to the findings of eukaryotic mediated nitrate reduction in some foraminifera and diatoms, nitrate respiration in gromiids seems to be mediated by bacterial endosymbionts. The role of endobionts in nitrate accumulating eukaryotes is of fundamental importance for understanding the evolutionary path...

  20. 2-Amino-5-chloropyridinium nitrate

    Directory of Open Access Journals (Sweden)

    Donia Zaouali Zgolli

    2009-11-01

    Full Text Available The title structure, C5H6ClN2+·NO3−, is held together by extensive hydrogen bonding between the NO3− ions and 2-amino-5-chloropyridinium H atoms. The cation–anion N—H...O hydrogen bonds link the ions into a zigzag- chain which develops parallel to the b axis. The structure may be compared with that of the related 2-amino-5-cyanopyridinium nitrate.

  1. 49 CFR 176.415 - Permit requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers.

    Science.gov (United States)

    2010-10-01

    ... nitrates, and certain ammonium nitrate fertilizers. 176.415 Section 176.415 Transportation Other... requirements for Division 1.5, ammonium nitrates, and certain ammonium nitrate fertilizers. (a) Except as... Captain of the Port (COTP). (1) Ammonium nitrate UN1942, ammonium nitrate fertilizers containing more...

  2. Kinetic versus thermodynamic factors in calcium renal lithiasis.

    Science.gov (United States)

    Grases, F; Costa-Bauzá, A; Königsberger, E; Königsberger, L C

    2000-01-01

    Calcium renal lithiasis formation depends on the balance between thermodynamic (supersaturation) and kinetic (inhibitors, nucleants) factors. In this paper, the importance of both groups was evaluated using (a) the complete urine analysis data obtained from 32 healthy volunteers and 141 active stone-formers, and (b) a comprehensive computer model to calculate the supersaturation values of calcium oxalate monohydrate, hydroxyapatite and brushite in each urine sample. The results of this evaluation were used to assess the possible effectiveness of a given pharmacological treatment.

  3. Sensitivity of nitrate aerosols to ammonia emissions and to nitrate chemistry: implications for present and future nitrate optical depth

    Directory of Open Access Journals (Sweden)

    F. Paulot

    2015-09-01

    Full Text Available We update and evaluate the treatment of nitrate aerosols in the Geophysical Fluid Dynamics Laboratory (GFDL atmospheric model (AM3. Accounting for the radiative effects of nitrate aerosols generally improves the simulated aerosol optical depth, although nitrate concentrations at the surface are biased high. This bias can be reduced by increasing the deposition of nitrate to account for the near-surface volatilization of ammonium nitrate or by neglecting the heterogeneous production of nitric acid to account for the inhibition of N2O5 reactive uptake at high nitrate concentrations. Globally, uncertainties in these processes can impact the simulated nitrate optical depth by up to 25 %, much more than the impact of uncertainties in the seasonality of ammonia emissions (6 % or in the uptake of nitric acid on dust (13 %. Our best estimate for present-day fine nitrate optical depth at 550 nm is 0.006 (0.005–0.008. We only find a modest increase of nitrate optical depth (2 (−40 % and ammonia (+38 % from 2010 to 2050. Nitrate burden is projected to increase in the tropics and in the free troposphere, but to decrease at the surface in the midlatitudes because of lower nitric acid concentrations. Our results suggest that better constraints on the heterogeneous chemistry of nitric acid on dust, on tropical ammonia emissions, and on the transport of ammonia to the free troposphere are needed to improve projections of aerosol optical depth.

  4. Sensitivity of nitrate aerosols to ammonia emissions and to nitrate chemistry: implications for present and future nitrate optical depth

    Science.gov (United States)

    Paulot, F.; Ginoux, P.; Cooke, W. F.; Donner, L. J.; Fan, S.; Lin, M.-Y.; Mao, J.; Naik, V.; Horowitz, L. W.

    2016-02-01

    We update and evaluate the treatment of nitrate aerosols in the Geophysical Fluid Dynamics Laboratory (GFDL) atmospheric model (AM3). Accounting for the radiative effects of nitrate aerosols generally improves the simulated aerosol optical depth, although nitrate concentrations at the surface are biased high. This bias can be reduced by increasing the deposition of nitrate to account for the near-surface volatilization of ammonium nitrate or by neglecting the heterogeneous production of nitric acid to account for the inhibition of N2O5 reactive uptake at high nitrate concentrations. Globally, uncertainties in these processes can impact the simulated nitrate optical depth by up to 25 %, much more than the impact of uncertainties in the seasonality of ammonia emissions (6 %) or in the uptake of nitric acid on dust (13 %). Our best estimate for fine nitrate optical depth at 550 nm in 2010 is 0.006 (0.005-0.008). In wintertime, nitrate aerosols are simulated to account for over 30 % of the aerosol optical depth over western Europe and North America. Simulated nitrate optical depth increases by less than 30 % (0.0061-0.010) in response to projected changes in anthropogenic emissions from 2010 to 2050 (e.g., -40 % for SO2 and +38 % for ammonia). This increase is primarily driven by greater concentrations of nitrate in the free troposphere, while surface nitrate concentrations decrease in the midlatitudes following lower concentrations of nitric acid. With the projected increase of ammonia emissions, we show that better constraints on the vertical distribution of ammonia (e.g., convective transport and biomass burning injection) and on the sources and sinks of nitric acid (e.g., heterogeneous reaction on dust) are needed to improve estimates of future nitrate optical depth.

  5. Statistical evaluation of effects of riparian buffers on nitrate and ground water quality

    Science.gov (United States)

    Spruill, T.B.

    2000-01-01

    A study was conducted to statistically evaluate the effectiveness of riparian buffers for decreasing nitrate concentrations in ground water and for affecting other chemical constituents. Values for pH, specific conductance, alkalinity, dissolved organic carbon (DOC), silica, ammonium, phosphorus, iron, and manganese at 28 sites in the Contentnea Creek Basin were significantly higher (p 20 yr) discharging ground water draining areas with riparian buffers compared with areas without riparian buffers. No differences in chloride, nitrate nitrogen, calcium, sodium, and dssolved oxygen concentrations in old ground water between buffer and nonbuffer areas were detected. Comparison of samples of young (20 yr) discharging ground water draining areas with riparian buffers compared with areas without riparian buffers. No differences in chloride, nitrate nitrogen, calcium, sodium, and dissolved oxygen concentrations in old ground water between buffer and nonbuffer areas were detected. Comparison of samples of young (conservative chemical constituents in young ground water that originate from fertilizer applications and also allow denitrification in ground water by providing an adequate source of organic carbon generated by vegetation in the buffer zone. Based on the median chloride and nitrate values for young ground water in the Contentnea Creek Basin, nitrate was 95% lower in buffer areas compared with nonbuffer areas, with a 30 to 35% reduction estimated to be due to dilution and 65 to 70% due to reduction and/or denitrification.Using data derived from a study area located in the Contentnea Creek Drainage Basin in North Carolina, the presence of riparian buffers 30-m wide or more and composed of lowland hardwood vegetation was assessed statistically in terms of nitrate-nitrogen concentrations in discharging groundwater passing beneath the buffers. The groundwater and surface-water sampling sites were selected by overlaying a digital coverage of a ma

  6. Calcium signaling and epilepsy.

    Science.gov (United States)

    Steinlein, Ortrud K

    2014-08-01

    Calcium signaling is involved in a multitude of physiological and pathophysiological mechanisms. Over the last decade, it has been increasingly recognized as an important factor in epileptogenesis, and it is becoming obvious that the excess synchronization of neurons that is characteristic for seizures can be linked to various calcium signaling pathways. These include immediate effects on membrane excitability by calcium influx through ion channels as well as delayed mechanisms that act through G-protein coupled pathways. Calcium signaling is able to cause hyperexcitability either by direct modulation of neuronal activity or indirectly through calcium-dependent gliotransmission. Furthermore, feedback mechanisms between mitochondrial calcium signaling and reactive oxygen species are able to cause neuronal cell death and seizures. Unravelling the complexity of calcium signaling in epileptogenesis is a daunting task, but it includes the promise to uncover formerly unknown targets for the development of new antiepileptic drugs.

  7. Effect of dietary nitrate level on enteric methane production, hydrogen emission, rumen fermentation, and nutrient digestibility in dairy cows

    DEFF Research Database (Denmark)

    Olijhoek, Dana; Hellwing, Anne Louise Frydendahl; Brask, Maike

    2016-01-01

    , microbial protein synthesis, and blood methemoglobin. In a 4 × 4 Latin square design 4 lactating Danish Holstein dairy cows fitted with rumen, duodenal, and ileal cannulas were assigned to 4 calcium ammonium nitrate addition levels: control, low, medium, and high [0, 5.3, 13.6, and 21.1 g of nitrate......, but did not constitute a threat for animal health and human food safety. Microbial crude protein synthesis and efficiency were unaffected. Total volatile fatty acid concentration and molar proportions of acetate, butyrate, and propionate were unaffected, whereas molar proportions of formate increased....... Milk yield, milk composition, DMI and digestibility of DM, organic matter, crude protein, and neutral detergent fiber in rumen, small intestine, hindgut, and total tract were unaffected by addition of nitrate. In conclusion, nitrate lowered methane production linearly with minor effects on rumen...

  8. Microdamage induced calcium efflux from bone matrix activates intracellular calcium signaling in osteoblasts via L-type and T-type voltage-gated calcium channels.

    Science.gov (United States)

    Jung, Hyungjin; Best, Makenzie; Akkus, Ozan

    2015-07-01

    Mechanisms by which bone microdamage triggers repair response are not completely understood. It has been shown that calcium efflux ([Ca(2+)]E) occurs from regions of bone undergoing microdamage. Such efflux has also been shown to trigger intracellular calcium signaling ([Ca(2+)]I) in MC3T3-E1 cells local to damaged regions. Voltage-gated calcium channels (VGCCs) are implicated in the entry of [Ca(2+)]E to the cytoplasm. We investigated the involvement of VGCC in the extracellular calcium induced intracellular calcium response (ECIICR). MC3T3-E1 cells were subjected to one dimensional calcium efflux from their basal aspect which results in an increase in [Ca(2+)]I. This increase was concomitant with membrane depolarization and it was significantly reduced in the presence of Bepridil, a non-selective VGCC inhibitor. To identify specific type(s) of VGCC in ECIICR, the cells were treated with selective inhibitors for different types of VGCC. Significant changes in the peak intensity and the number of [Ca(2+)]I oscillations were observed when L-type and T-type specific VGCC inhibitors (Verapamil and NNC55-0396, respectively) were used. So as to confirm the involvement of L- and T-type VGCC in the context of microdamage, cells were seeded on devitalized notched bone specimen, which were loaded to induce microdamage in the presence and absence of Verapamil and NNC55-0396. The results showed significant decrease in [Ca(2+)]I activity of cells in the microdamaged regions of bone when L- and T-type blockers were applied. This study demonstrated that extracellular calcium increase in association with damage depolarizes the cell membrane and the calcium ions enter the cell cytoplasm by L- and T-type VGCCs.

  9. Reduction of nitrates in Cucumis sativus L. seedlings II. Influence of tungsten and vanadium on nitrate reductase and adenosine triphosphatase activities

    Directory of Open Access Journals (Sweden)

    Józef Buczek

    2014-02-01

    Full Text Available ATPases isolated from the roots of cucumber seedlings activated by Mg+2 ions in experiments in vitro, were fairly distinctly inhibited by Ca-2 ions, very slightly inhibited by fluorides and molybdenum ions while NO3- anions had no effect on the level of ATPase activity studied. Introduction into the nutrient of 10-4 M Na2WO4 or 10-3 M Na VO3 (inhibitors of nitrate reductase NR distinctly inhibited activity of the ATPase under study especially of fractions IIa and III, and inhibited NR activity and lowered uptake of NO3-. WO4-2 and VO3 inhibited to the same extent absorption and reduction of NO3- in the initial phase of NR induction, whereas at a later stage both inhibitors checked reduction to a greater degree than uptake of NO3-. The results indicate the possibility of certain ATPase participation in assimilating nitrates, and suggest that in the initial stage of biosynthesis of the NR enzyme system, activity of the enzyme is distinctly dependent upon NO3- transport and the level of NR activity limited by the amount of nitrate taken up. At a later an additional mechanism of NO3- transport probably functions, not connected with simultaneous reduction of nitrates. On the basis of results the Butz and Jackson (1977 hypothesis concerning a model for the absorption and reduction of NO3- by plant tissues is discussed.

  10. EFFECTS OF PDGF-BB ON INTRACELLULAR CALCIUM CONCENTRATION AND PROLIFERATION IN CULTURED GLOMERULAR MESANGIAL CELLS

    Institute of Scientific and Technical Information of China (English)

    WEN Li-ping; ZHANG Chong; BIAN Fan; ZOU Jun; JIANG Geng-ru; ZHU Han-wei

    2006-01-01

    Objective To investigate the relationship between the alteration of intracellular calcium concentration and proliferation in cultured glomerular mesangial cells. Methods Rat mesangial cells were cultured.Intracellular calcium concentrations were measured by confocal Laser Scanning Microscopy and Fura-3 fluorescence dyeing techniques. Cell growth was measured by MTT assay. Results PDGF-BB increased intracellular calcium concentrations in a dose-dependent manner, and at the same time promote the proliferation of mesangial cells. After preincubation with calcium channel blocker nifedipine or angiotensin converting enzyme inhibitor captopril, both the increase of intracellular calcium concentrations and cell proliferations induced by PDGF-BB were inhibited. Tripterigium Wilfordii Glycosides (TMG) significantly inhibited the mesangial cell proliferations, but it had no significant effect on intracellular calcium concentrations. Conclusion There was a positive relationship between the elevation of intracellular calcium concentration and cell proliferation in glomerular mesangial cells, but the increase of in- tracellular calcium concentrations wasn't the only way for proliferation.

  11. Interaction of neodymium nitrate with rubidium and cesium nitrates

    Energy Technology Data Exchange (ETDEWEB)

    Molodkin, A.K.; Odinets, Z.K.; S' ' edina, T.V.; Ivanova, T.N. (Universitet Druzhby Narodov, Moscow (USSR))

    1982-12-01

    The Rb/sub 2/Nd(NO/sub 3/)/sub 5/xH/sub 2/O (1) and Cs/sub 2/Nd(NO/sub 3/)/sub 5/xH/sub 2/O (2) new complexes are prepared. The crystals 1 are isotropic, of cubic crystal system, Ng=1.570+-0.002; 2 - Ng=1.582+-0.002; Csub(Np)=0-9 degrees, of low crystal system (syngony). The bands of coordinated nitrate group, the ..delta nu..=..nu../sub 4/(B/sub 2/)-..nu../sub 1/(A/sub 1/) splitting value is respectively equal to 225 and 230 cm/sup -1/ are present in the infrared absorption spectra of the compounds. The interplane distances and corresponding intensities for the 1, 2 and hexahydrate of neodymium nitrate are determined. Derivatograms of the compounds are recorded, the final products of the thermolysis are correspondingly RbNdO/sub 2/ and Nd/sub 2/O/sub 3/.

  12. Nitrate contamination of groundwater and its countermeasures

    Energy Technology Data Exchange (ETDEWEB)

    Mitamura, Hisayoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    The inevitable increases of food production and energy consumption with an increase in world population become main causes of an increase of nitrate load to the environment. Although nitrogen is essential for the growth of animal and plant as a constituent element of protein, excessive nitrate load to the environment contaminates groundwater resources used as drinking water and leads to seriously adverse effects on the health of man and livestock. In order to clarify the problem of nitrate contamination of groundwater and search a new trend of technology development from the viewpoint of environment remediation and protection, the present paper has reviewed adverse effects of nitrate on human health, the actual state of nitrogen cycle, several kinds of nitrate sources, measures for reducing nitrate level, etc. (author)

  13. Effect of coolant inhibitors on AZ91D

    Institute of Scientific and Technical Information of China (English)

    I.M. Baghni; WU Yinshun; ZHANG Wei; LI Jiuqing

    2004-01-01

    The inhibition effects of sodium vanadate along with inorganic coolant inhibitors were examined on corrosion of AZ91D in ASTM D1384-80 corrosive water by polarization measurements. The galvanic corrosion of AZ91D coupled to 3003, 6063, and 356 Al alloys were also tested. An effective combination of inhibitors containing (but not limited to) sodium vanadate, silicate, and nitrate was proposed for inhibition of AZ91D and prevention of galvanic corrosion.

  14. Nitrate leaching from Silage Maize

    OpenAIRE

    Hansen, Elly Møller; Eriksen, Jørgen

    2009-01-01

    During the last 20 years the area with maize in Denmark has increased dramatically and reached 163,000 ha in 2008. Silage maize is easy to grow, is a suitable fodder for cows and goes well with grass-clover in the diet. This means that silage maize is often found in crop rotations with grass-clover on sandy soils in western Denmark. The ploughing in of grass-clover fields poses a serious risk of increased nitrate leaching on a coarse sandy soil, even when carried out in spring. With increased...

  15. KINETICS STUDY ON NITRATION OF METHYL RICINOLEATE

    OpenAIRE

    Abdullah, Abdullah; Triyono, Triyono; Trisunaryanti, Wega; Haryadi, Winarto

    2012-01-01

    Kinetics parameter values of methyl ricinoleate nitration (rate constant, reaction order and the rate of reaction) have been determined. Nitration was carried out with both concentrations of HNO3 and acetic anhydride in excess to the concentration of methyl ricinoleate. Thus, the kinetics parameter value was only affected by the concentration of methyl ricinoleate. Based on kinetic study conducted, it could be concluded that the nitration follows pseudo first-order, and the reaction rate for ...

  16. Nephrotoxic effects of lead nitrate in Rana ridibunda.

    Science.gov (United States)

    Loumbourdis, N S

    2003-09-01

    The impact of lead (Pb) on kidney histopathology of the frog Rana ridibunda was investigated. Female frogs were exposed for 4, 10 and 30 days to 14 ppm lead (as lead nitrate). All the lead concentrations and many histological changes were time dependent. Light microscopy of kidney revealed morphological changes mainly in the proximal convoluted tubule (PCT) cells. The most severe changes such as vacuolation, Perl's stained material, infiltration, brush border destruction and proximal tubule damage were detected in the animals exposed for 10 and 30 days. Karyomegaly was highest at 10-days exposure, probably as a result of intense stress caused by the lead. Some PCT in the 30-days-exposed animals were von Kossa's method positive, suggesting the presence of calcium. The possibility is discussed that some of these changes, such as karyomegaly and intranuclear inclusions, might be preneoplastic if lead was supplied at high concentrations and for long time.

  17. Nephrotoxic effects of lead nitrate in Rana ridibunda

    Energy Technology Data Exchange (ETDEWEB)

    Loumbourdis, N.S. [Department of Zoology, University of Thessaloniki, 54124, Thessaloniki (Greece)

    2003-09-01

    The impact of lead (Pb) on kidney histopathology of the frog Rana ridibunda was investigated. Female frogs were exposed for 4, 10 and 30 days to 14 ppm lead (as lead nitrate). All the lead concentrations and many histological changes were time dependent. Light microscopy of kidney revealed morphological changes mainly in the proximal convoluted tubule (PCT) cells. The most severe changes such as vacuolation, Perl's stained material, infiltration, brush border destruction and proximal tubule damage were detected in the animals exposed for 10 and 30 days. Karyomegaly was highest at 10-days exposure, probably as a result of intense stress caused by the lead. Some PCT in the 30-days-exposed animals were von Kossa's method positive, suggesting the presence of calcium. The possibility is discussed that some of these changes, such as karyomegaly and intranuclear inclusions, might be preneoplastic if lead was supplied at high concentrations and for long time. (orig.)

  18. Measurement of isoprene nitrates by GCMS

    Science.gov (United States)

    Mills, Graham P.; Hiatt-Gipson, Glyn D.; Bew, Sean P.; Reeves, Claire E.

    2016-09-01

    According to atmospheric chemistry models, isoprene nitrates play an important role in determining the ozone production efficiency of isoprene; however this is very poorly constrained through observations as isoprene nitrates have not been widely measured. Measurements have been severely restricted largely due to a limited ability to measure individual isoprene nitrate isomers. An instrument based on gas chromatography/mass spectrometry (GCMS) and the associated calibration methods are described for the speciated measurements of individual isoprene nitrate isomers. Five of the primary isoprene nitrates which formed in the presence of NOx by reaction of isoprene with the hydroxyl radical (OH) in the Master Chemical Mechanism are identified using known isomers on two column phases and are fully separated on the Rtx-200 column. Three primary isoprene nitrates from the reaction of isoprene with the nitrate radical (NO3) are identified after synthesis from the already identified analogous hydroxy nitrate. A Tenax adsorbent-based trapping system allows the analysis of the majority of the known hydroxy and carbonyl primary isoprene nitrates, although not the (1,2)-IN isomer, under field-like levels of humidity and showed no impact from typical ambient concentrations of NOx and ozone.

  19. Nitration of Phenol Catalyzed by Horseradish Peroxidase

    Institute of Scientific and Technical Information of China (English)

    DAI Rong-ji; HUANG Hui; TONG Bin; XIAO Sheng-yuan

    2007-01-01

    Horseradish peroxidase, an acidic peroxidase from the horseradish, is one of the most important enzymes as analytical reagent.The enzymatic nitration of phenol by oxidation of nitrite was studied using horseradish peroxidase in the presence of H2O2.The results showed that nitration occur at 2- and 4- positions of phenol.There were also minor products of hydroquinone and catechol.The influence of various reaction parameters, including pH, organic solvent, and concentration of H2O2, on nitration products were discussed.The best nitration pH was 7.0, and H2O2 should be added to the reaction mixture slowly.

  20. Trend Analyses of Nitrate in Danish Groundwater

    Science.gov (United States)

    Hansen, B.; Thorling, L.; Dalgaard, T.; Erlandsen, M.

    2012-04-01

    This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribution, trends and trend reversals in the groundwater nitrate concentration. Secondly, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Thirdly, groundwater recharge CFC (Chlorofluorocarbon) age determination allows linking of the first two dataset. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater. Regulation and technical improvements in the intensive farming in Denmark have succeeded in decreasing the N surplus by 40% since the mid 1980s while at the same time maintaining crop yields and increasing the animal production of especially pigs. Trend analyses prove that the youngest (0-15 years old) oxic groundwater shows more pronounced significant downward nitrate trends (44%) than the oldest (25-50 years old) oxic groundwater (9%). This amounts to clear evidence of the effect of reduced nitrate leaching on groundwater nitrate concentrations in Denmark. Are the Danish groundwater monitoring strategy obtimal for detection of nitrate trends? Will the nitrate concentrations in Danish groundwater continue to decrease or are the Danish nitrate concentration levels now appropriate according to the Water Framework Directive?

  1. Calcium is important forus.

    Institute of Scientific and Technical Information of China (English)

    高利平

    2005-01-01

    Calcium is important for our health.We must have it in our diet to stay well.A good place to get it is from dairy products like milk, cheese and ice cream.One pound of cheese has fifty times the calcium we should have every day.Other foods have less.For example,a pound of beans also has calcium.But it has only three times the amount we ought to have daily.

  2. Effect of Indole Butyric Acid on the Transportation of Stored Calcium in Malus hupehensis Rhed. Seedling

    Institute of Scientific and Technical Information of China (English)

    LI Jia; YANG Hong-qiang; YAN Tian-li; SHU Huai-rui

    2006-01-01

    Calcium (Ca) plays an important role in the metabolism of higher plants. Recently, research on Ca2+ in plants has been focused especially at the cellular and molecular levels. Uptake, transport, and distribution are also very important for Ca to accomplish its function at the whole-plant level. In this experiment, one-year-old apple seedlings (M. hupehensis Rehd.) were investigated to determine the distribution of stored Ca, the different forms of Ca, and Ca2+-ATPase activity after treatment with indole butyric acid (IBA). The results showed that the total Ca measured in mature leaves and Ca2+-ATPase activity in tender leaves were higher compared with those in the control (CK). Calcium nitrate and calcium chloride (ALe-Ca) and calcium phosphate and calcium carbonate (HAC-Ca) decreased in both mature leaves and shoots,whereas water-soluble calcium (H2O-Ca), calcium pectate (NaCl-Ca), and calcium oxalate (HCl-Ca) increased. The percentage of active calcium, calcium pectate, and water-soluble calcium increased, whereas the percentage of calcium phosphate and calcium carbonate decreased. When treated with IBA, calcium fractions and percentage of the different forms of Ca was enhanced in 40 part per million (ppm) IBA compared with 20 ppm IBA and water. The results indicated that IBA increased the percentage of both active calcium (NaCl-Ca and H2O-Ca) in tender shoots and boosted the transportation of stored Ca in plants. IBA promoted Ca2+-ATPase activity and Ca2+ uptake in tender shoots of M. hupehensis. It can improve the total Ca contents and the relative percentage of Ca.

  3. Inhibition of crystallization of calcium oxalate by the extraction of Tamarix gallica L.

    Science.gov (United States)

    Bensatal, Ahmed; Ouahrani, M R

    2008-12-01

    The main objective is to study the inhibitor effect of acid fraction of the extract of Tamarix gallica L on the crystallization of calcium oxalate. The extract of Tamarix gallica L is very rich by acid compounds that are used as an inhibitor of nephrolithiasis (calcium oxalate). Our study of the calcium oxalate crystallization is based on the model of turbidimetry by means of a spectrophotometer. The calcium oxalate formation is induced by the addition of oxalate solutions of sodium and of calcium chloride. The addition of inhibitor with various concentrations enabled us to give information on the percentage of inhibition. The comparison between the turbidimetric slopes with and without inhibitor gives the effectiveness of inhibitor for the acid fraction. By comparing the photographs of with and without inhibitor, we concluded that the extract of Tamarix gallica L acts at the stage of growth. The acid fraction of the extract of Tamarix gallica L gives an activity remarkable in the formation of urinary lithiasis (calcium oxalate); this effectiveness is due to the presence of functions of acid.

  4. Yttrium Nitrate mediated Nitration of Phenols at room temperature in Glacial Acetic acid

    Indian Academy of Sciences (India)

    MOHABUL A MONDAL; DBASHIS MANDAL; KANCHAN MITRA

    2017-01-01

    Rapid nitration of electron rich phenols using Y(NO₃)₃.6H₂O in glacial acetic acid at room temperature was observed with good yield. The method allows nitration of phenols without oxidation, and isolation of nitration product in a rapid and simple way. The described method is selective for phenols.

  5. Challenges with nitrate therapy and nitrate tolerance: prevalence, prevention, and clinical relevance.

    Science.gov (United States)

    Thadani, Udho

    2014-08-01

    Nitrate therapy has been an effective treatment for ischemic heart disease for over 100 years. The anti-ischemic and exercise-promoting benefits of sublingually administered nitrates are well established. Nitroglycerin is indicated for the relief of an established attack of angina and for prophylactic use, but its effects are short lived. In an effort to increase the duration of beneficial effects, long-acting orally administered and topical applications of nitrates have been developed; however, following their continued or frequent daily use, patients soon develop tolerance to these long-acting nitrate preparations. Once tolerance develops, patients begin losing the protective effects of the long-acting nitrate therapy. By providing a nitrate-free interval, or declining nitrate levels at night, one can overcome or reduce the development of tolerance, but cannot provide 24-h anti-anginal and anti-ischemic protection. In addition, patients may be vulnerable to occurrence of rebound angina and myocardial ischemia during periods of absent nitrate levels at night and early hours of the morning, and worsening of exercise capacity prior to the morning dose of the medication. This has been a concern with nitroglycerin patches but not with oral formulations of isosorbide-5 mononitrates, and has not been adequately studied with isosorbide dinitrate. This paper describes problems associated with nitrate tolerance, reviews mechanisms by which nitrate tolerance and loss of efficacy develop, and presents strategies to avoid nitrate tolerance and maintain efficacy when using long-acting nitrate formulations.

  6. Climate-induced changes in high elevation stream nitrate dynamics

    Science.gov (United States)

    Baron, J.S.; Schmidt, T.M.; Hartman, M.D.

    2009-01-01

    Mountain terrestrial and aquatic ecosystems are responsive to external drivers of change, especially climate change and atmospheric deposition of nitrogen (N). We explored the consequences of a temperature-warming trend on stream nitrate in an alpine and subalpine watershed in the Colorado Front Range that has long been the recipient of elevated atmospheric N deposition. Mean annual stream nitrate concentrations since 2000 are higher by 50% than an earlier monitoring period of 1991-1999. Mean annual N export increased by 28% from 2.03 kg N ha-1yr-1 before 2000 to 2.84 kg N ha-1yr-1 in Loch Vale watershed since 2000. The substantial increase in N export comes as a surprise, since mean wet atmospheric N deposition from 1991 to 2006 (3.06 kg N ha-1 yr-1) did not increase. There has been a period of below average precipitation from 2000 to 2006 and a steady increase in summer and fall temperatures of 0.12??C yr-1 in both seasons since 1991. Nitrate concentrations, as well as the weathering products calcium and sulfate, were higher for the period 2000-2006 in rock glacier meltwater at the top of the watershed above the influence of alpine and subalpine vegetation and soils. We conclude the observed recent N increases in Loch Vale are the result of warmer summer and fall mean temperatures that are melting ice in glaciers and rock glaciers. This, in turn, has exposed sediments from which N produced by nitrification can be flushed. We suggest a water quality threshold may have been crossed around 2000. The phenomenon observed in Loch Vale may be indicative of N release from ice features such as rock glaciers worldwide as mountain glaciers retreat. ?? 2009 Blackwell Publishing Ltd.

  7. Clinical efficacy of efonidipine hydrochloride, a T-type calcium channel inhibitor, on sympathetic activities. Examination using spectral analysis of heart rate/blood pressure variabilities and {sup 123}I-Metaiodobenzylguanidine myocardial scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Kenji; Nomura, Masahiro; Nishikado, Akiyoshi; Uehara, Kouzoh; Nakaya, Yutaka; Ito, Susumu [Tokushima Univ. (Japan). School of Medicine

    2003-02-01

    Dihydropyridine Ca antagonists cause reflex tachycardia related to their hypotensive effects. Efonidipine hydrochloride has inhibitory effects on T-type Ca channels, even as it inhibits reflex tachycardia. In the present study, the influence of efonidipine hydrochloride on heart rate and autonomic nervous function was investigated. Using an electrocardiogram and a tonometric blood pressure measurement, autonomic nervous activity was evaluated using spectral analysis of heart rate/systolic blood pressure variability. Three protocols were used: a single dose of efonidipine hydrochloride was administered orally to healthy subjects with resting heart rate values of 75 beats/min or more (high-heart rate (HR) group) and to healthy subjects with resting heart rate values less than 75 beats/min (low-HR group); efonidipine hydrochloride was newly administered to untreated patients with essential hypertension, and autonomic nervous activity was investigated after a 4-week treatment period; and patients with high heart rate values ({>=}75 beats/min) who had been treated with a dihydropyridine L-type Ca channel inhibitor for 1 month or more were switched to efonidipine hydrochloride and any changes in autonomic nervous activity were investigated. In all protocols, administration of efonidipine hydrochloride decreased the heart rate in patients with a high heart rate, reduced sympathetic nervous activity, and enhanced parasympathetic nervous activity. In addition, myocardial scintigraphy with {sup 123}I-metaiodobenzylguanidine showed significant improvement in the washout rate and heart to mediastinum (H/M) ratio of patients who were switched from other dihydropyridine Ca antagonists to efonidipine hydrochloride. Efonidipine hydrochloride inhibits increases in heart rate and has effects on the autonomic nervous system. It may be useful for treating hypertension and angina pectoris, and may also have a cardiac protective function. (author)

  8. Anatase-brookite mixed phase nano TiO2 catalyzed homolytic decomposition of ammonium nitrate.

    Science.gov (United States)

    Vargeese, Anuj A; Muralidharan, Krishnamurthi

    2011-09-15

    Compared to the conventional ammonium perchlorate based solid rocket propellants, burning of ammonium nitrate (AN) based propellants produce environmentally innocuous combustion gases. Application of AN as propellant oxidizer is restricted due to low reactivity and low energetics besides its near room temperature polymorphic phase transition. In the present study, anatase-brookite mixed phase TiO(2) nanoparticles (~ 10 nm) are synthesized and used as catalyst to enhance the reactivity of the environmental friendly propellant oxidizer ammonium nitrate. The activation energy required for the decomposition reactions, computed by differential and non-linear integral isoconversional methods are used to establish the catalytic activity. Presumably, the removal of NH(3) and H(2)O, known inhibitors of ammonium nitrate decomposition reaction, due to the surface reactions on active surface of TiO(2) changes the decomposition pathway and thereby the reactivity.

  9. Hydrothermal Formation of Calcium Copper Tetrasilicate.

    Science.gov (United States)

    Johnson-McDaniel, Darrah; Comer, Sara; Kolis, Joseph W; Salguero, Tina T

    2015-12-01

    We describe the first hydrothermal synthesis of CaCuSi4 O10 as micron-scale clusters of thin platelets, distinct from morphologies generated under salt-flux or solid-state conditions. The hydrothermal reaction conditions are surprisingly specific: too cold, and instead of CaCuSi4 O10 , a porous calcium copper silicate forms; too hot, and calcium silicate (CaSiO3 ) forms. The precursors also strongly impact the course of the reaction, with the most common side product being sodium copper silicate (Na2 CuSi4 O10 ). Optimized conditions for hydrothermal CaCuSi4 O10 formation from calcium chloride, copper(II) nitrate, sodium silicate, and ammonium hydroxide are 350 °C at 3000 psi for 72 h; at longer reaction times, competitive delamination and exfoliation causes crystal fragmentation. These results illustrate that CaCuSi4 O10 is an even more unique material than previously appreciated.

  10. Regulation of nitrate assimilation in cyanobacteria.

    Science.gov (United States)

    Ohashi, Yoshitake; Shi, Wei; Takatani, Nobuyuki; Aichi, Makiko; Maeda, Shin-ichi; Watanabe, Satoru; Yoshikawa, Hirofumi; Omata, Tatsuo

    2011-02-01

    Nitrate assimilation by cyanobacteria is inhibited by the presence of ammonium in the growth medium. Both nitrate uptake and transcription of the nitrate assimilatory genes are regulated. The major intracellular signal for the regulation is, however, not ammonium or glutamine, but 2-oxoglutarate (2-OG), whose concentration changes according to the change in cellular C/N balance. When nitrogen is limiting growth, accumulation of 2-OG activates the transcription factor NtcA to induce transcription of the nitrate assimilation genes. Ammonium inhibits transcription by quickly depleting the 2-OG pool through its metabolism via the glutamine synthetase/glutamate synthase cycle. The P(II) protein inhibits the ABC-type nitrate transporter, and also nitrate reductase in some strains, by an unknown mechanism(s) when the cellular 2-OG level is low. Upon nitrogen limitation, 2-OG binds to P(II) to prevent the protein from inhibiting nitrate assimilation. A pathway-specific transcriptional regulator NtcB activates the nitrate assimilation genes in response to nitrite, either added to the medium or generated intracellularly by nitrate reduction. It plays an important role in selective activation of the nitrate assimilation pathway during growth under a limited supply of nitrate. P(II) was recently shown to regulate the activity of NtcA negatively by binding to PipX, a small coactivator protein of NtcA. On the basis of accumulating genome information from a variety of cyanobacteria and the molecular genetic data obtained from the representative strains, common features and group- or species-specific characteristics of the response of cyanobacteria to nitrogen is summarized and discussed in terms of ecophysiological significance.

  11. Evaluation of nitrates in albanian wines

    Directory of Open Access Journals (Sweden)

    Ariola Morina

    2013-05-01

    Full Text Available Nitrates are important compounds in nature but not desirable if they are present in wine at increased amount. The high level of nitrate is attributed to the use of nitrogen fertilizers in the vineyards. Method of the reactive Gries I and Gries II was used for the determination of nitrates in wine. There were analyzed 45 white wines and 55 red wines produced in 2008 – 2010, as well as wines produced from Albanian grape varieties Shesh i Bardhë and Shesh i Zi in 2009 and 2010, as an authentic wines evidence with denominated origin. From the results of analyses was observed that, in 51 % of white wines was found that the content of nitrates were less than 5 mg/l, in 46% of them the nitrates level goes up to 10 mg/l and only in 3 % of them the amount of nitrates is up to 12 mg/l. None of white wine samples have the content of nitrates over 20 mg/l. In this case there is no doubt for water addition during wine preparation. In regards of red wines, in 34% of them the amount of nitrates is up to 5 mg/l, in 30% of them up to 10 mg/l, while in 26% of them the amount of nitrates is 20 mg/l. Only 10 % of red wines have nitrates content over 20 mg/l which raise dubiety for falsified wines where water and sugar is added in the red marc. The level of nitrates in wines with denominated origin was under 20 mg/L.

  12. Statistical analysis of nitrate in ground water, West Salt River Valley, Arizona

    Science.gov (United States)

    Long, Andy E.; Brown, James G.; Gellenbeck, Dorinda J.

    1997-01-01

    Accurate estimates of the nitrate concentrations in ground water in west Salt River Valley are needed to better manage ground water affected by nitrate. Statistical analyses were done to establish the best statistical method to produce these estimates. Three sets of ground-water data for different time periods --1975-77, 1980-85, and 1986-90--were used to analyze spatial and temporal variations in concentrations of nitrate in ground water. The use of inverse-distance squared weighting, radial-basis function, kriging, and cokriging were evaluated for estimating nitrate concentrations in ground water. From an analysis of the cross-validation results, cokriging maps resulted in the best estimates, and they were accepted as being the most reliable. Cross-validation results also indicated that nitrate cokriged best with magnesium for 1975-77 and 1986-90 and with calcium for 1980-85. Kriging results consistently were almost as reliable as any of the cokriging results. Because of the difficulties inherent in the cokriging process, kriging, although not optimal, was the fastest way to obtain reasonably good results. In 1980-85, cokriged nitrate concentrations exceeded 20 milligrams per liter in a 12-square-kilometer area in Phoenix and Glendale and exceeded 10 milligrams per liter in a 280-square-kilometer area that extended to the Salt River. In 1986-90, nitrate concentrations along the entire reach of the Salt River in west Salt River Valley were less than 10 milligrams per liter and were smaller probably as a result of recharge from the Salt and Gila Rivers in 1982. Farther north in Phoenix and Glendale, the area in which nitrate concentrations exceeded 10 milligrams per liter expanded to 490 square kilometers for 1986-90. In Buckeye Valley, nitrate concentrations exceeded 10 milligrams per liter in an area of 300 square milometers for 1980-85 from the Gila River in the early 1980's but possibly could be an artifact of the different data distributions associated with

  13. Reactions between water-soluble organic acids and nitrates in atmospheric aerosols: Recycling of nitric acid and formation of organic salts

    Science.gov (United States)

    Wang, Bingbing; Laskin, Alexander

    2014-03-01

    Atmospheric particles often include a complex mixture of nitrate and secondary organic materials accumulated within the same individual particles. Nitrate as an important inorganic component can be chemically formed in the atmosphere. For instance, formation of sodium nitrate (NaNO3) and calcium nitrate (Ca(NO3)2) occurs when nitrogen oxides and nitric acid (HNO3) react with sea salt and calcite, respectively. Organic acids contribute a significant fraction of photochemically formed secondary organics that can condense on the preexisting nitrate-containing particles. Here we present a systematic microanalysis study on chemical composition of laboratory-generated particles composed of water-soluble organic acids and nitrates (i.e., NaNO3 and Ca(NO3)2) using computer-controlled scanning electron microscopy with energy-dispersive X-ray microanalysis and Fourier transform infrared microspectroscopy. The results show that water-soluble organic acids can react with nitrates and release gaseous HNO3 during the dehydration process. These reactions are attributed to acid displacement of nitrate with weak organic acids driven by the evaporation of HNO3 into gas phase because of its relatively high volatility. The reactions result in significant nitrate depletion and formation of organic salts in mixed organic acids/nitrate particles that, in turn, may affect their physical and chemical properties relevant to atmospheric environment and climate. Airborne nitrate concentrations are estimated by thermodynamic calculations corresponding to various nitrate depletions in selected organic acids of atmospheric relevance. The results indicate a potential mechanism of HNO3 recycling that may further affect concentrations of gas and condensed phase species in the atmosphere and the heterogeneous reaction chemistry between them.

  14. Ammonium nitrate fertiliser production based on biomass - environmental effects from a life cycle perspective.

    Science.gov (United States)

    Ahlgren, Serina; Baky, Andras; Bernesson, Sven; Nordberg, Ke; Norén, Olle; Hansson, Per-Anders

    2008-11-01

    Ammonium nitrate and calcium ammonium nitrate are the most commonly used straight nitrogen fertilisers in Europe, accounting for 43% of the total nitrogen used for fertilisers. They are both produced in a similar way; carbonate can be added as a last step to produce calcium ammonium nitrate. The environmental impact, fossil energy input and land use from using gasified biomass (cereal straw and short rotation willow (Salix) coppice) as feedstock in ammonium nitrate production were studied in a cradle-to-gate evaluation using life cycle assessment methodology. The global warming potential in the biomass systems was only 22-30% of the impact from conventional production using natural gas. The eutrophication potential was higher for the biomass systems due to nutrient leaching during cultivation, while the acidification was about the same in all systems. The primary fossil energy use was calculated to be 1.45 and 1.37MJ/kg nitrogen for Salix and straw, respectively, compared to 35.14MJ for natural gas. The biomass production was assumed to be self-supporting with nutrients by returning part of the ammonium nitrate produced together with the ash from the gasification. For the production of nitrogen from Salix, it was calculated that 3914kg of nitrogen can be produced every year from 1ha, after that 1.6% of the produced nitrogen has been returned to the Salix production. From wheat straw, 1615kg of nitrogen can be produced annually from 1ha, after that 0.6% of the nitrogen has been returned.

  15. [Effects of nitrate on organic removal and microbial community structure in the sediments].

    Science.gov (United States)

    Liu, Jin; Deng, Dai-Yong; Sun, Guo-Ping; Liu, Yong-Ding; Xu, Mei-Ying

    2013-07-01

    The strategy promoted pollutant degradation and transformation under the anaerobic circumstance by adding nitrate as an electron acceptor has been widely used in sediment bioremediation. However, few literature reports on organic removal characteristics and microbial community responses in the contaminated river sediment under the nitrate reduction condition. Methods including the polar and non-polar chemical fractionation, relative abundance detection of organic matters by GC-MS were combined and applied to investigate organic removals and PCR-DGGE analysis was used for microbial community structures in sediment incubation systems with or without calcium nitrate addition. The results indicated that the addition of calcium nitrate could significantly enhance removal efficiencies of organic pollutants. The removal efficiency of total organic carbon (TOC) and the total peak area of organic matters in GC-MS were 47.25% and 29.55% which were higher than those of the control. The effect descending order of organic pollutants was: silicon materials > alkanes > polycyclic aromatic hydrocarbons > heterocyclic compounds > olefins > benzene homologues > polar compounds > phthalates > aldehydes and ketones > alkyl esters. And removal rates of silicon materials, the persistent organic pollutants, benzene homologues and heterocyclic compounds were 46.73%, 36.25%, 23.19% and 35.92% which were higher than those of the control. The PCR-DGGE profile of bacterial 16S rDNA V3 fragments showed obviously different microbial community structures between the treatment and the control systems. Blastn analysis revealed that sequences of 10 predominant bands from DGGE profile were closely related to Proteobacteria, Actinobacteria, Clostridia, Chloroflexi, Caldiserica and uncultured bacterium. The research findings provide some helpful scientific information for promoting organic pollutant removal of river sediment by nitrate reduction.

  16. Nitrate reduction functional genes and nitrate reduction potentials persist in deeper estuarine sediments. Why?

    Directory of Open Access Journals (Sweden)

    Sokratis Papaspyrou

    Full Text Available Denitrification and dissimilatory nitrate reduction to ammonium (DNRA are processes occurring simultaneously under oxygen-limited or anaerobic conditions, where both compete for nitrate and organic carbon. Despite their ecological importance, there has been little investigation of how denitrification and DNRA potentials and related functional genes vary vertically with sediment depth. Nitrate reduction potentials measured in sediment depth profiles along the Colne estuary were in the upper range of nitrate reduction rates reported from other sediments and showed the existence of strong decreasing trends both with increasing depth and along the estuary. Denitrification potential decreased along the estuary, decreasing more rapidly with depth towards the estuary mouth. In contrast, DNRA potential increased along the estuary. Significant decreases in copy numbers of 16S rRNA and nitrate reducing genes were observed along the estuary and from surface to deeper sediments. Both metabolic potentials and functional genes persisted at sediment depths where porewater nitrate was absent. Transport of nitrate by bioturbation, based on macrofauna distributions, could only account for the upper 10 cm depth of sediment. A several fold higher combined freeze-lysable KCl-extractable nitrate pool compared to porewater nitrate was detected. We hypothesised that his could be attributed to intracellular nitrate pools from nitrate accumulating microorganisms like Thioploca or Beggiatoa. However, pyrosequencing analysis did not detect any such organisms, leaving other bacteria, microbenthic algae, or foraminiferans which have also been shown to accumulate nitrate, as possible candidates. The importance and bioavailability of a KCl-extractable nitrate sediment pool remains to be tested. The significant variation in the vertical pattern and abundance of the various nitrate reducing genes phylotypes reasonably suggests differences in their activity throughout the

  17. Nitrate Reduction Functional Genes and Nitrate Reduction Potentials Persist in Deeper Estuarine Sediments. Why?

    Science.gov (United States)

    Papaspyrou, Sokratis; Smith, Cindy J.; Dong, Liang F.; Whitby, Corinne; Dumbrell, Alex J.; Nedwell, David B.

    2014-01-01

    Denitrification and dissimilatory nitrate reduction to ammonium (DNRA) are processes occurring simultaneously under oxygen-limited or anaerobic conditions, where both compete for nitrate and organic carbon. Despite their ecological importance, there has been little investigation of how denitrification and DNRA potentials and related functional genes vary vertically with sediment depth. Nitrate reduction potentials measured in sediment depth profiles along the Colne estuary were in the upper range of nitrate reduction rates reported from other sediments and showed the existence of strong decreasing trends both with increasing depth and along the estuary. Denitrification potential decreased along the estuary, decreasing more rapidly with depth towards the estuary mouth. In contrast, DNRA potential increased along the estuary. Significant decreases in copy numbers of 16S rRNA and nitrate reducing genes were observed along the estuary and from surface to deeper sediments. Both metabolic potentials and functional genes persisted at sediment depths where porewater nitrate was absent. Transport of nitrate by bioturbation, based on macrofauna distributions, could only account for the upper 10 cm depth of sediment. A several fold higher combined freeze-lysable KCl-extractable nitrate pool compared to porewater nitrate was detected. We hypothesised that his could be attributed to intracellular nitrate pools from nitrate accumulating microorganisms like Thioploca or Beggiatoa. However, pyrosequencing analysis did not detect any such organisms, leaving other bacteria, microbenthic algae, or foraminiferans which have also been shown to accumulate nitrate, as possible candidates. The importance and bioavailability of a KCl-extractable nitrate sediment pool remains to be tested. The significant variation in the vertical pattern and abundance of the various nitrate reducing genes phylotypes reasonably suggests differences in their activity throughout the sediment column. This

  18. Nitration of soluble proteins in organotypic culture models of Parkinson's disease.

    Science.gov (United States)

    Larsen, Trine R; Söderling, Ann-Sofi; Caidahl, Kenneth; Roepstorff, Peter; Gramsbergen, Jan Bert

    2008-02-01

    Protein nitration due to oxidative and nitrative stress has been linked to the pathogenesis of Parkinson's disease (PD), but its relationship to the loss of dopamine (DA) or tyrosine hydroxylase (TH) activity is not clear. Here we quantified protein-bound 3-nitrotyrosine (3-NT) by a novel gas chromatography/negative chemical ionization tandem mass spectrometry technique and DA and 3,4-dihydroxyphenylalanine (DOPA) by HPLC in tissues or medium of organotypic, mouse mesencephalon cultures after acute or chronic treatments with the peroxynitrite donor 3-morpholino-sydnonimine (SIN-1), the dopaminergic toxin 1-methyl-4-phenylpyridinium (MPP(+)) or the lipophilic complex I inhibitor rotenone. Incubation with SIN-1 (24 h) or MPP(+) treatments (48 h) caused dose-dependent protein nitration reaching a maximum of eightfold increase by 10 mM SIN-1 or twofold by 10 microM MPP(+), but significant DA depletions occurred at much lower concentrations of MPP(+) (1 microM). Chronic MPP(+) or rotenone treatments (3 weeks) caused maximum protein nitration by 1 microM (twofold) or 10nM (fourfold), respectively. Co-treatment with the nitric oxide synthase inhibitor l-NAME (300 microM) prevented protein nitration by MPP(+), but did not protect against MPP(+)-induced DA depletion or inhibition of TH activity. Acute incubation with 100 microM SIN-1 inhibited TH activity, which could be blocked by co-treatment with the tetrahydrobiopterin precursor l-sepiapterin, but tissue DA depletions required higher doses of SIN-1 (>1 mM, 24 h) and longer survival. In conclusion, protein nitration and TH activity or DA depletion are not directly related in these models.

  19. Acidosis and Urinary Calcium Excretion

    DEFF Research Database (Denmark)

    Alexander, R Todd; Cordat, Emmanuelle; Chambrey, Régine

    2016-01-01

    Metabolic acidosis is associated with increased urinary calcium excretion and related sequelae, including nephrocalcinosis and nephrolithiasis. The increased urinary calcium excretion induced by metabolic acidosis predominantly results from increased mobilization of calcium out of bone and inhibi...

  20. Calcium binding to cardiac myocytes protected from proteolytic enzyme activity.

    Science.gov (United States)

    Bailey, L E; Fawzi, A B

    1985-04-17

    Excitation-contraction coupling in cardiac muscle is dependent on extracellular calcium and calcium bound to the surface of the myocardial cell. In this study, we examined the physical characteristics of calcium binding to adult guinea pig ventricular myocytes disaggregated mechanically in oxygenated tissue culture medium containing a proteinase inhibitor (aprotinin), and separated from cellular debris by Cytodex beads. Cells prepared in this manner excluded Trypan blue and showed no evidence of spontaneous contraction or contracture. Scatchard plots of calcium binding determined by continuous flow equilibrium dialysis revealed a high-affinity, low-capacity pool, Ka = 65 X 10(3) M-1 and Bt = 1.3 nmol X mg-1 and a low-affinity, high-capacity pool, Ka = 141 M-1 and Bt = 138 nmol X mg-1. The low-affinity pool was not detectable after lanthanum, trypsin or collagenase treatment or in cells prepared without aprotinin in the isolation medium. Both neuraminidase and phospholipase C reduced Bt of the low-affinity pool by one half, but only neuraminidase affected the affinity constant of this pool. Ka was increased to 516.7 M-1, similar to the apparent affinity constant for calcium binding estimated from dP/dtmax measured at several extracellular calcium concentrations (470 M-1). The results suggest that calcium bound to sarcolemmal phospholipids represents the superficial calcium involved in excitation-contraction coupling in the heart.

  1. Dietary Nitrate, Nitric Oxide, and Cardiovascular Health.

    Science.gov (United States)

    Bondonno, Catherine P; Croft, Kevin D; Hodgson, Jonathan M

    2016-09-09

    Emerging evidence strongly suggests that dietary nitrate, derived in the diet primarily from vegetables, could contribute to cardiovascular health via effects on nitric oxide (NO) status. NO plays an essential role in cardiovascular health. It is produced via the classical L-arginine-NO-synthase pathway and the recently discovered enterosalivary nitrate-nitrite-NO pathway. The discovery of this alternate pathway has highlighted dietary nitrate as a candidate for the cardioprotective effect of a diet rich in fruit and vegetables. Clinical trials with dietary nitrate have observed improvements in blood pressure, endothelial function, ischemia-reperfusion injury, arterial stiffness, platelet function, and exercise performance with a concomitant augmentation of markers of NO status. While these results are indicative of cardiovascular benefits with dietary nitrate intake, there is still a lingering concern about nitrate in relation to methemoglobinemia, cancer, and cardiovascular disease. It is the purpose of this review to present an overview of NO and its critical role in cardiovascular health; to detail the observed vascular benefits of dietary nitrate intake through effects on NO status as well as to discuss the controversy surrounding the possible toxic effects of nitrate.

  2. 4-Methoxy-N,N′-diphenylbenzamidinium nitrate

    Directory of Open Access Journals (Sweden)

    Renata S. Silva

    2016-09-01

    Full Text Available The asymmetric unit of the title salt N,N′-diphenyl-4-methoxybenzamidinium nitrate, C20H19N2O+·NO3−, comprises two independent N,N′-diphenyl-4-methoxybenzamidinium cations and two nitrate anions. The crystal structure features N—H...O hydrogen bonds and C—H...O contacts responsible for the packing.

  3. Calcium signaling in neurodegeneration

    Directory of Open Access Journals (Sweden)

    Dreses-Werringloer Ute

    2009-05-01

    Full Text Available Abstract Calcium is a key signaling ion involved in many different intracellular and extracellular processes ranging from synaptic activity to cell-cell communication and adhesion. The exact definition at the molecular level of the versatility of this ion has made overwhelming progress in the past several years and has been extensively reviewed. In the brain, calcium is fundamental in the control of synaptic activity and memory formation, a process that leads to the activation of specific calcium-dependent signal transduction pathways and implicates key protein effectors, such as CaMKs, MAPK/ERKs, and CREB. Properly controlled homeostasis of calcium signaling not only supports normal brain physiology but also maintains neuronal integrity and long-term cell survival. Emerging knowledge indicates that calcium homeostasis is not only critical for cell physiology and health, but also, when deregulated, can lead to neurodegeneration via complex and diverse mechanisms involved in selective neuronal impairments and death. The identification of several modulators of calcium homeostasis, such as presenilins and CALHM1, as potential factors involved in the pathogenesis of Alzheimer's disease, provides strong support for a role of calcium in neurodegeneration. These observations represent an important step towards understanding the molecular mechanisms of calcium signaling disturbances observed in different brain diseases such as Alzheimer's, Parkinson's, and Huntington's diseases.

  4. Association between calcium intake, parathormone levels and blood pressure during pregnancy

    Directory of Open Access Journals (Sweden)

    Anibal Nieto

    2009-06-01

    Full Text Available Purpose: To evaluate the association between calcium intake from diet, calciotropic hormones (PTH, PTH-rp, vasoactive regulators (endothelin, nitric oxide and blood pressure levels during pregnancy, birth and puerperium.Method: In a prospective study 149 healthy normotensive primigravidas were followed-up from 15 weeks of gestation to puerperium. Daily calcium intake, calciuria, PTH, PTH-rp, endothelin, nitrite-nitrate, and Holter Test were assessed. Linear regression models were performed to evaluate the association between calcium intake, blood pressure levels and the laboratory tests. Multivariate regression models were performed to control potential confounders.Results: A significant increase of calcium intake during pregnancy was observed (931±301 mg/day to 1,195±467 mg/day, p<0.001. Plasma PTH-rp, endothelin, and nitrite-nitrate levels did not change during pregnancy. Among the women 38 (25.4% had low calcium intake (<800 mg/day with a larger increase of systolic and diastolic blood pressure during pregnancy (p=0.04 birth (p=0.006 and puerperium (p=0.01. After adjusting for other factors the multivariate analyses showed statistical association between low calcium intake, high parathormone levels and high systolic blood pressure levels during pregnancy (p=0.002.Conclusion: Low calcium intake during pregnancy is associated with a larger increase of systolic blood pressure and high parathormone levels.

  5. Nitrate reduction in an unconfined sandy aquifer

    DEFF Research Database (Denmark)

    Postma, Diederik Jan; Boesen, Carsten; Kristiansen, Henning;

    1991-01-01

    Nitrate distribution and reduction processes were investigated in an unconfined sandy aquifer of Quaternary age. Groundwater chemistry was studied in a series of eight multilevel samplers along a flow line, deriving water from both arable and forested land. Results show that plumes of nitrate...... processes of O2 and NO3- occur at rates that are fast compared to the rate of downward water transport. Nitrate-contaminated groundwater contains total contents of dissolved ions that are two to four times higher than in groundwater derived from the forested area. The persistence of the high content...... of total dissolved ions in the NO3- free anoxic zone indicates the downward migration of contaminants and that active nitrate reduction is taking place. Nitrate is apparently reduced to N2 because both nitrite and ammonia are absent or found at very low concentrations. Possible electron donors...

  6. Novel Peptide with Specific Calcium-Binding Capacity from Schizochytrium sp. Protein Hydrolysates and Calcium Bioavailability in Caco-2 Cells

    Science.gov (United States)

    Cai, Xixi; Lin, Jiaping; Wang, Shaoyun

    2016-01-01

    Peptide-calcium can probably be a suitable supplement to improve calcium absorption in the human body. In this study, a specific peptide Phe-Tyr (FY) with calcium-binding capacity was purified from Schizochytrium sp. protein hydrolysates through gel filtration chromatography and reversed phase HPLC. The calcium-binding capacity of FY reached 128.77 ± 2.57 μg/mg. Results of ultraviolet spectroscopy, fluorescence spectroscopy, and infrared spectroscopy showed that carboxyl groups, amino groups, and amido groups were the major chelating sites. FY-Ca exhibited excellent thermal stability and solubility, which were beneficial to be absorbed and transported in the basic intestinal tract of the human body. Moreover, the calcium bioavailability in Caco-2 cells showed that FY-Ca could enhance calcium uptake efficiency by more than three times when compared with CaCl2, and protect calcium ions against dietary inhibitors, such as tannic acid, oxalate, phytate, and Zn2+. Our findings further the progress of algae-based peptide-calcium, suggesting that FY-Ca has the potential to be developed as functionally nutraceutical additives. PMID:28036002

  7. Novel Peptide with Specific Calcium-Binding Capacity from Schizochytrium sp. Protein Hydrolysates and Calcium Bioavailability in Caco-2 Cells

    Directory of Open Access Journals (Sweden)

    Xixi Cai

    2016-12-01

    Full Text Available Peptide-calcium can probably be a suitable supplement to improve calcium absorption in the human body. In this study, a specific peptide Phe-Tyr (FY with calcium-binding capacity was purified from Schizochytrium sp. protein hydrolysates through gel filtration chromatography and reversed phase HPLC. The calcium-binding capacity of FY reached 128.77 ± 2.57 μg/mg. Results of ultraviolet spectroscopy, fluorescence spectroscopy, and infrared spectroscopy showed that carboxyl groups, amino groups, and amido groups were the major chelating sites. FY-Ca exhibited excellent thermal stability and solubility, which were beneficial to be absorbed and transported in the basic intestinal tract of the human body. Moreover, the calcium bioavailability in Caco-2 cells showed that FY-Ca could enhance calcium uptake efficiency by more than three times when compared with CaCl2, and protect calcium ions against dietary inhibitors, such as tannic acid, oxalate, phytate, and Zn2+. Our findings further the progress of algae-based peptide-calcium, suggesting that FY-Ca has the potential to be developed as functionally nutraceutical additives.

  8. Role of calcium in growth inhibition induced by a novel cell surface sialoglycopeptide

    Science.gov (United States)

    Betz, N. A.; Westhoff, B. A.; Johnson, T. C.; Spooner, B. S. (Principal Investigator)

    1995-01-01

    Our laboratory has purified an 18 kDa cell surface sialoglycopeptide growth inhibitor (CeReS-18) from intact bovine cerebral cortex cells. Evidence presented here demonstrates that sensitivity to CeReS-18-induced growth inhibition in BALB-c 3T3 cells is influenced by calcium, such that a decrease in the calcium concentration in the growth medium results in an increase in sensitivity to CeReS-18. Calcium did not alter CeReS-18 binding to its cell surface receptor and CeReS-18 does not bind calcium directly. Addition of calcium, but not magnesium, to CeReS-18-inhibited 3T3 cells results in reentry into the cell cycle. A greater than 3-hour exposure to increased calcium is required for escape from CeReS-18-induced growth inhibition. The calcium ionophore ionomycin could partially mimic the effect of increasing extracellular calcium, but thapsigargin was ineffective in inducing escape from growth inhibition. Increasing extracellular calcium 10-fold resulted in an approximately 7-fold increase in total cell-associated 45Ca+2, while free intracellular calcium only increased approximately 30%. However, addition of CeReS-18 did not affect total cell-associated calcium or the increase in total cell-associated calcium observed with an increase in extracellular calcium. Serum addition induced mobilization of intracellular calcium and influx across the plasma membrane in 3T3 cells, and pretreatment of 3T3 cells with CeReS-18 appeared to inhibit these calcium mobilization events. These results suggest that a calcium-sensitive step exists in the recovery from CeReS-18-induced growth inhibition. CeReS-18 may inhibit cell proliferation through a novel mechanism involving altering the intracellular calcium mobilization/regulation necessary for cell cycle progression.

  9. Differential mitochondrial calcium responses in different cell types detected with a mitochondrial calcium fluorescent indicator, mito-GCaMP2

    Institute of Scientific and Technical Information of China (English)

    Min Chen; Yanru Wang; Tingting Hou; Huiliang Zhang; Aijuan Qu; Xianhua Wang

    2011-01-01

    Mitochondrial calcium plays a crucial role in mitochondriai metabolism,cell calcium handling,and cell death.However,some mechanisms concerning mitochondrial calcium regulation are still unknown,especially how mitochondrial calcium couples with cytosolic calcium.In this work,we constructed a novel mitochondrial calcium fluorescent indicator (mito-GCaMP2) by genetic manipulation.Mito-GCaMP2 was imported into mitochondria with high efficiency and the fluorescent signals co-localized with that of tetramethyl rhodamine methyl ester,a mitochondrial membrane potential indicator.The mitochondrial inhibitors specifically decreased the signals of mito-GCaMP2.The apparent Kd of mito-GCaMP2 was 195.0 nmol/L at pH 8.0 in adult rat cardiomyocytes.Furthermore,we observed that mito-GCaMP2 preferred the alkaline pH surrounding of mitochondria.In HeLa cells,we found that mitochondrial calcium ([Ca2+]mito)responded to the changes of cytosolic calcium ([Ca2+]cyto)induced by histamine or thapasigargin.Moreover,external Ca2+ (100 μmol/L) directly induced an increase of [Ca2+]mito in permeabilized HeLa cells.However,in rat cardiomyocytes [Ca2+]mito did not respond to cytosolic calcium transients stimulated by electric pacing or caffeine.In permeabilized cardiomyocytes,600 nmol/L free Ca2+ repeatedly increased the fluorescent signals of mito-GCaMP2,which excluded the possibility that mito-GCaMP2 lost its function in cardiomyocytes mitochondria.These results showed that the response of mitochondrial calcium is diverse in different cell lineages and suggested that mitochondria in cardiomyocytes may have a special defense mechanism to control calcium flux.

  10. Proteomic identification of age-dependent protein nitration in rat skeletal muscle.

    Science.gov (United States)

    Kanski, Jaroslaw; Alterman, Michail A; Schöneich, Christian

    2003-11-15

    Age-related protein nitration was studied in skeletal muscle of Fisher 344 and Fisher 344/Brown Norway (BN) F1 rats by a proteomic approach. Proteins from young (4 months) and old (24 months) Fisher 344 rats and young (6 months) and old (34 months) Fisher 344/BN F1 animals were separated by 2-D gel electrophoresis. Western blot showed an age-related increase in the nitration of a few specific proteins, which were identified by MALDI-TOF MS and ESI-MS/MS. We identified age-dependent apparent nitration of beta-enolase, alpha-fructose aldolase, and creatine kinase, which perform important functions in muscle energy metabolism, suggesting that the nitration of such key proteins can be, in part, responsible for the decline of muscle motor function of the muscle. Furthermore, we have identified the apparent nitration of succinate dehydrogenase, rab GDP dissociation inhibitor beta (GdI-2), triosephosphate isomerase, troponin I, alpha-crystallin, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH).

  11. [The role of mitochondrial uniporter in calcium-homeostasis of the exorbital lacrimal gland secretory cells].

    Science.gov (United States)

    Kotliarova, A B; Merlavs'kyĭ, V M; Dorosh, O M; Man'ko, V V

    2014-01-01

    The role of mitochondrial calcium-uniporter in calcium-homeostasis maintenance and correlations of calcium-uniporter with other calcium-transport systems of the rat exorbital lacrimal gland secretory cells were studied. The experiments were performed on intact and digitonin-permeabilized cells. The interdependence of calcium-uniporter and other calcium-transporting systems functioning was estimated on the basis of additivity of their inhibitors/agonists effects, which was accompanied with a decrease in the Ca2+ content in the gland cells. It was found that in conditions of simultaneously inhibition of sarco endoplasmic reticulum Ca2+-ATPase (SERCA) and mitochondrial calcium-uniporter Ca2+ passively released from different calcium stores, because the effects of these calcium-transport systems inhibitors (thapsigargin and ruthenium red, respectively) were additive. Similarly, the processes of inositol-1,4,5-trisphosphate receptors (IP3Rs) activation and calcium-uniporter inhibition were additive. In contrast, the effects of ryanodine and ruthenium red on the Ca2+ content in cells were significantly non-additive. In addition, ryanodine at concentrations 1-3 μM reduced respiration rate of studied cells in dose-dependent manner, and this effect was persisted at cells preincubation with ruthenium red or tapsigargin. Thus, besides the activation of ryanodine receptors (RyRs) in endoplasmic reticulum, ryanodine inhibits Ca2+ influx to the mitochondrial matrix, that was insensitive to ruthenium red.

  12. Silver-doped calcium phosphate nanoparticles: synthesis, characterization, and toxic effects toward mammalian and prokaryotic cells.

    Science.gov (United States)

    Peetsch, Alexander; Greulich, Christina; Braun, Dieter; Stroetges, Christian; Rehage, Heinz; Siebers, Bettina; Köller, Manfred; Epple, Matthias

    2013-02-01

    Spherical silver-doped calcium phosphate nanoparticles were synthesized in a co-precipitation route from calcium nitrate/silver nitrate and ammonium phosphate in a continuous process and colloidally stabilized by carboxymethyl cellulose. Nanoparticles with 0.39 wt% silver content and a diameter of about 50-60 nm were obtained. The toxic effects toward mammalian and prokaryotic cells were determined by viability tests and determination of the minimal inhibitory and minimal bactericidal concentrations (MIC and MBC). Three mammalian cells lines, i.e. human mesenchymal stem cells (hMSC) and blood peripheral mononuclear cells (PBMC, monocytes and T-lymphocytes), and two prokaryotic strains, i.e. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were used. Silver-doped calcium phosphate nanoparticles and silver acetate showed similar effect toward mammalian and prokaryotic cells with toxic silver concentrations in the range of 1-3 μg mL(-1).

  13. New organic nitrate-containing benzyloxy isonipecotanilide derivatives with vasodilatory and anti-platelet activity.

    Science.gov (United States)

    de Candia, Modesto; Marini, Elisabetta; Zaetta, Giorgia; Cellamare, Saverio; Di Stilo, Antonella; Altomare, Cosimo D

    2015-05-25

    A number of new nitric oxide (NO)-precursors were synthesized by grafting nitrate-containing moieties on the structures of the benzyloxy isonipecotanilide derivatives 1 and 2 already reported as moderately potent antiplatelet agents. Various nitrooxy (ONO2)-alkyl side chains were covalently linked to the piperidine nitrogen of the parent compounds through carbamate and amide linkage, and the synthesis of a benzyl nitrate analog (15) of compound 1 was also achieved. The in vitro vasodilatory activities, as well as platelet anti-aggregatory effects, of the newly synthesized organic nitrates were assessed. The (ONO2)methyl carbamate-based derivative 5a and the benzyl nitrate analog 15, which on the other hand retain activity as inhibitors of ADP-induced platelet aggregation, exhibited strong NO-mediated vasodilatory effects on pre-contracted rat aorta strips, with EC50 values in the low nanomolar range (13 and 29 nM, respectively). Experiments carried out with the selectively inhibited soluble guanylate cyclase (sGC), which is the key enzyme of the NO-mediated pathway leading to vascular smooth muscle relaxation, confirmed the involvement of NO in the observed vasodilation. The nitrate derivatives proved to be stable in acidic aqueous solution and at pH 7.4. In human serum, unlike 5a, which showed not to undergo enzyme-catalyzed decomposition, the other tested (ONO2)-alkyl carbamate-based compounds (5b and 5e) and benzyl nitrate 15 underwent a faster degradation. However, their decomposition rates in serum were quite slow (t½>2.6 h), which suggests that nitrate moiety is poorly metabolized in blood plasma and that much of the in vitro anti-platelet activity has to be attributed to the intact (ONO2)-containing molecules.

  14. Phosphorylation of erythrocyte membrane liberates calcium

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, V.P.S.; Brockerhoff, H.

    1986-05-01

    Phosphorylation of permeabilized erythrocyte ghost membranes with ATP results in an increase free calcium level as measured with the help of Ca/sup 2 +/ electrode and /sup 45/Ca. This effect could not be observed in the presence of p/sup -/ chloromercuric benzoate, an inhibitor of kinases. The rise in the free calcium due to phosphorylation of the membrane was accompanied by a decrease in the level of phosphatidylinositol (PI) and an increase in phosphatidylinositolmonophosphate (PIP) and phosphatidylinositolbisphosphate (PIP/sub 2/). These results support the proposal that an inositol shuttle, PI in equilibrium PIP in equilibrium PIP/sub 2/, operates to maintain the intracellular calcium concentration. The cation is believed to be sequestered in a cage formed by the head groups of two acidic phospholipid molecules, e.g., phosphatidylserine and phosphatidylinositol, with the participation of both PO and fatty acid ester CO groups. When the inositol group of such a cage is phosphorylated, inter-headgroup hydrogen bonding between the lipids is broken. As a result the cage opens and calcium is released.

  15. Modeling nitrate removal in a denitrification bed.

    Science.gov (United States)

    Ghane, Ehsan; Fausey, Norman R; Brown, Larry C

    2015-03-15

    Denitrification beds are promoted to reduce nitrate load in agricultural subsurface drainage water to alleviate the adverse environmental effects associated with nitrate pollution of surface water. In this system, drainage water flows through a trench filled with a carbon media where nitrate is transformed into nitrogen gas under anaerobic conditions. The main objectives of this study were to model a denitrification bed treating drainage water and evaluate its adverse greenhouse gas emissions. Field experiments were conducted at an existing denitrification bed. Evaluations showed very low greenhouse gas emissions (mean N2O emission of 0.12 μg N m(-2) min(-1)) from the denitrification bed surface. Field experiments indicated that nitrate removal rate was described by Michaelis-Menten kinetics with the Michaelis-Menten constant of 7.2 mg N L(-1). We developed a novel denitrification bed model based on the governing equations for water flow and nitrate removal kinetics. The model evaluation statistics showed satisfactory prediction of bed outflow nitrate concentration during subsurface drainage flow. The model can be used to design denitrification beds with efficient nitrate removal which in turn leads to enhanced drainage water quality.

  16. Photodegradation of Paracetamol in Nitrate Solution

    Science.gov (United States)

    Meng, Cui; Qu, Ruijuan; Liang, Jinyan; Yang, Xi

    2010-11-01

    The photodegradation of paracetamol in nitrate solution under simulated solar irradiation has been investigated. The degradation rates were compared by varying environmental parameters including concentrations of nitrate ion, humic substance and pH values. The quantifications of paracetamol were conducted by HPLC method. The results demonstrate that the photodegradation of paracetamol followed first-order kinetics. The photoproducts and intermediates of paracetamol in the presence of nitrate ions were identified by extensive GC-MS method. The photodegradation pathways involving. OH radicals as reactive species were proposed.

  17. Activation of L-type calcium channels is required for gap junction-mediated intercellular calcium signaling in osteoblastic cells

    DEFF Research Database (Denmark)

    Jørgensen, Niklas Rye; Teilmann, Stefan Cuoni; Henriksen, Zanne

    2003-01-01

    The propagation of mechanically induced intercellular calcium waves (ICW) among osteoblastic cells occurs both by activation of P2Y (purinergic) receptors by extracellular nucleotides, resulting in "fast" ICW, and by gap junctional communication in cells that express connexin43 (Cx43), resulting...... in "slow" ICW. Human osteoblastic cells transmit intercellular calcium signals by both of these mechanisms. In the current studies we have examined the mechanism of slow gap junction-dependent ICW in osteoblastic cells. In ROS rat osteoblastic cells, gap junction-dependent ICW were inhibited by removal...... of extracellular calcium, plasma membrane depolarization by high extracellular potassium, and the L-type voltage-operated calcium channel inhibitor, nifedipine. In contrast, all these treatments enhanced the spread of P2 receptor-mediated ICW in UMR rat osteoblastic cells. Using UMR cells transfected to express Cx...

  18. Calcium and Your Child

    Science.gov (United States)

    ... for dinner. Create mini-pizzas by topping whole-wheat English muffins or bagels with pizza sauce, low- ... Minerals Do I Need to Drink Milk? Lactose Intolerance Becoming a Vegetarian Soy Foods and Health Calcium ...

  19. Stoichiometry of Calcium Medicines

    Science.gov (United States)

    Pinto, Gabriel

    2005-01-01

    The topic of calcium supplement and its effects on human lives is presented in the way of questions to the students. It enables the students to realize the relevance of chemistry outside the classroom surrounding.

  20. Dietary Nitrate Is a Modifier of Vascular Gene Expression in Old Male Mice

    Directory of Open Access Journals (Sweden)

    Christos Rammos

    2015-01-01

    Full Text Available Aging leads to a number of disadvantageous changes in the cardiovascular system. Deterioration of vascular homoeostasis with increase in oxidative stress, chronic low-grade inflammation, and impaired nitric oxide bioavailability results in endothelial dysfunction, increased vascular stiffness, and compromised arterial-ventricular interactions. A chronic dietary supplementation with the micronutrient nitrate has been demonstrated to improve vascular function. Healthy dietary patterns may regulate gene expression profiles. However, the mechanisms are incompletely understood. The changes that occur at the gene expression level and transcriptional profile following a nutritional modification with nitrate have not been elucidated. To determine the changes of the vascular transcriptome, we conducted gene expression microarray experiments on aortas of old mice, which were treated with dietary nitrate. Our results highlight differentially expressed genes overrepresented in gene ontology categories. Molecular interaction and reaction pathways involved in the calcium-signaling pathway and the detoxification system were identified. Our results provide novel insight to an altered gene-expression profile in old mice following nitrate supplementation. This supports the general notion of nutritional approaches to modulate age-related changes of vascular functions and its detrimental consequences.

  1. Trace concentration - Huge impact: Nitrate in the calcite/Eu(III) system

    Science.gov (United States)

    Hofmann, Sascha; Voïtchovsky, Kislon; Schmidt, Moritz; Stumpf, Thorsten

    2014-01-01

    The interactions of trivalent lanthanides and actinides with secondary mineral phases such as calcite is of high importance for the safety assessment of deep geological repositories for high level nuclear waste (HLW). Due to similar ionic radii, calcium-bearing mineral phases are suitable host minerals for Ln(III) and An(III) ions. Especially calcite has been proven to retain these metal ions effectively by both surface complexation and bulk incorporation. Since anionic ligands (e.g., nitrate) are omnipresent in the geological environment and due to their coordinating properties, their influence on retentive processes should not be underestimated. Nitrate is a common contaminant in most HLW forms as a result of using nitric acid in fuel reprocessing. It is also formed by microbial activity under aerobic conditions. In this study, atomic force microscopy investigations revealed a major influence of nitrate upon the surface of calcite crystals. NaNO3 causes serious modifications even in trace amounts (surface layer of low crystallinity on top of the calcite crystal. Time-resolved laser fluorescence spectroscopy of Eu(III) showed that, within this layer, Eu(III) ions are incorporated, while losing most of their hydration shell. The results show that solid solution modelling for actinides in calcite must take into account the presence of nitrate in pore and ground waters.

  2. The Laschamp geomagnetic excursion featured in nitrate record from EPICA-Dome C ice core

    Science.gov (United States)

    Traversi, R.; Becagli, S.; Poluianov, S.; Severi, M.; Solanki, S. K.; Usoskin, I. G.; Udisti, R.

    2016-01-01

    Here we present the first direct comparison of cosmogenic 10Be and chemical species in the period of 38–45.5 kyr BP spanning the Laschamp geomagnetic excursion from the EPICA-Dome C ice core. A principal component analysis (PCA) allowed to group different components as a function of the main sources, transport and deposition processes affecting the atmospheric aerosol at Dome C. Moreover, a wavelet analysis highlighted the high coherence and in-phase relationship between 10Be and nitrate at this time. The evident preferential association of 10Be with nitrate rather than with other chemical species was ascribed to the presence of a distinct source, here labelled as “cosmogenic”. Both the PCA and wavelet analyses ruled out a significant role of calcium in driving the 10Be and nitrate relationship, which is particularly relevant for a plateau site such as Dome C, especially in the glacial period during which the Laschamp excursion took place. The evidence that the nitrate record from the EDC ice core is able to capture the Laschamp event hints toward the possibility of using this marker for studying galactic cosmic ray flux variations and thus also major geomagnetic field excursions at pluri-centennial-millennial time scales, thus opening up new perspectives in paleoclimatic studies. PMID:26819064

  3. The potential for calcium depletion in forest ecosystems of southeastern United States: Review and analysis

    Science.gov (United States)

    Huntington, Thomas G.

    2000-06-01

    Biogeochemical mass balance assessments of calcium status in southeastern forests indicate that losses through harvesting and soil leaching often exceed inputs from atmospheric deposition and weathering. Many forest soils of the southeastern United States are particularly sensitive because these soils and the underlying saprolite from which these soils are derived are largely depleted of weatherable calcium. At most of the intensively studied sites in the southeastern United States, it is estimated that calcium depletion has already reduced or will likely reduce exchangeable soil calcium reserves to less than the estimated requirement for a merchantable forest stand in 150 years or less. At most sites, calcium uptake into merchantable wood equals or exceeds soil leaching losses. Chronic atmospheric deposition of sulfate and nitrate and declining atmospheric deposition of calcium are likely to accelerate calcium depletion. The southeastern U.S. regional distribution of soil calcium pools and calcium fluxes (deposition and uptake in merchantable wood) indicates that the depletion status of the intensively studied sites is representative of a substantially larger area. Where weathering inputs are insufficient to replace leaching and uptake losses, there is a potential for a regional problem in forest nutrition over the long term.

  4. Physico-chemical properties and toxic effect of fruit-ripening agent calcium carbide

    Directory of Open Access Journals (Sweden)

    Mohammad Asif

    2012-01-01

    Full Text Available Ripening is the final stage of the maturation process, when the fruit changes color, softens and develops the flavor, texture and aroma that constitute optimum eating quality. This study was conducted to discuss the use of unsatisfactory calcium carbide to ripen fruits for domestic markets as well as their toxic effects on human health. The commonly used ripening agents are calcium carbide, acetylene, ethylene, propylene, ethrel (2-chloroethyl phosphonic acid, glycol, ethanol and some other agents. The calcium carbide is one of the most commonly used ripening agent for fruits, while other calcium salts like calcium ammonium nitrate, calcium chloride and calcium sulfate are used to delay fruit ripening agents for local fruit industries. The use of calcium carbide is being discouraged worldwide, due to associated health hazards. Calcium carbide treatment of food is extremely hazardous because it contains traces of arsenic and phosphorous, and once dissolved in water, it produces acetylene gas. Arsenic, phosphorous and acetylene gas may affect the different body organs and causes various health problems like headache, dizziness, mood disturbances, sleepiness, mental confusion, memory loss, cerebral edema, seizures and prolonged hypoxia.

  5. Denitrification of nitrate waste solutions

    Energy Technology Data Exchange (ETDEWEB)

    Bertolami, R.J.; Chao, E.I.; Choi, W.M.; Johnson, B.R.; Varlet, J.L.P.

    1976-04-26

    Growth rates for the denitrifying bacteria Pseudomonas Stutzeri were studied to minimize the time necessary to start up a bacterial denitrification reactor. Batch experiments were performed in nine 250-ml Erlenmeyer flasks, a 7-liter fermentor, and a 67-liter fermentor. All reactors maintained an anaerobic environment. Initial microorganism inoculum concentration was varied over four orders of magnitude. Initial nitrate and substrate carbon concentrations were varied from 200 to 6000 ppm and from 56 to 1596 ppm, respectively, with a carbon-to-nitrogen weight ratio of 1.18. In all experiments, except those with the highest initial substrate-to-bacteria ratio, no growth was observed due to substrate depletion during the lag period. In those experiments which did exhibit an increase in bacterial population, growth also stopped due to substrate depletion. A model simulating microbe growth during the induction period was developed, but insufficient data were available to properly adjust the model constants. Because of this, the model does not accurately predict microbe growth. The metabolism of Pseudomonas Stutzeri was studied in detail. This resulted in a prediction of the denitrification stoichiometry during steady state reactor operation. Iron was found to be an important component for bacterial anabolism.

  6. Impact of Sulfide on Nitrate Conversion in Eutrophic Nitrate-Rich Marine Sludge

    DEFF Research Database (Denmark)

    Schwermer, Carsten U.; Krieger, Bärbel; Lavik, Gaute

    2006-01-01

    IMPACT OF SULFIDE ON NITRATE CONVERSION IN EUTROPHIC NITRATE-RICH MARINE SLUDGE C.U. Schwermer 1, B.U. Krieger 2, G. Lavik 1, A. Schramm 3, J. van Rijn 4, D. de Beer 1, D. Minz 5, E. Cytryn 4, M. Kuypers 1, A. Gieseke 1 1 Max Planck Institute for Marine Microbiology, Bremen, Germany; 2 Dept...... nitrate conversion from denitrification to dissimilatory nitrate-reduction to ammonium (DNRA). In situ microsensor profiling in stagnant sludge revealed the typical stratification of nitrate reduction on top of sulfate reduction. Increasing the bulk nitrate concentration lead to a downward shift....... Our results show that the presence of sulfide generally decreased growth rates but increased N2O production. We conclude that sulfide plays a key role in causing incomplete denitrification, presumably by inhibiting the N2O reductase, and enhancing DNRA compared to denitrification.  ...

  7. Calcium and Calcium-Base Alloys

    Science.gov (United States)

    1949-01-01

    should be satisfactory, because the electrolytic process for •(!>: A. H. Everts and G. D. Baglev’, " Physical «nrt m<„.+„4 i «_ of Calcium«, Electrochem...Rev. Metalurgie , 3j2, (1), 129 (1935). 10 ^sm^mssss^ma^^ extension between two known loads, is preferable to the value of 3,700,000 p.B.i. obtained

  8. Removal of Nitrate from Groundwater by Cyanobacteria: Quantitative Assessment of Factors Influencing Nitrate Uptake

    OpenAIRE

    Hu, Qiang; Westerhoff, Paul; Vermaas, Wim

    2000-01-01

    The feasibility of biologically removing nitrate from groundwater was tested by using cyanobacterial cultures in batch mode under laboratory conditions. Results demonstrated that nitrate-contaminated groundwater, when supplemented with phosphate and some trace elements, can be used as growth medium supporting vigorous growth of several strains of cyanobacteria. As cyanobacteria grew, nitrate was removed from the water. Of three species tested, Synechococcus sp. strain PCC 7942 displayed the h...

  9. Qualitative Determination of Nitrate with Triphenylbenzylphosphonium Chloride.

    Science.gov (United States)

    Berry, Donna A.; Cole, Jerry J.

    1984-01-01

    Discusses two procedures for the identification of nitrate, the standard test ("Brown Ring" test) and a new procedure using triphenylbenzylphosphonium chloride (TPBPC). Effectiveness of both procedures is compared, with the TPBPC test proving to be more sensitive and accurate. (JM)

  10. Nitrate reduction in geologically heterogeneous catchments

    DEFF Research Database (Denmark)

    Refsgaard, Jens Christian; Auken, Esben; Bamberg, C.A.;

    2014-01-01

    In order to fulfil the requirements of the EU Water Framework Directive nitrate load from agricultural areas to surface water in Denmark needs to be reduced by about 40%. The regulations imposed until now have been uniform, i.e. the same restrictions for all areas independent of the subsurface...... conditions. Studies have shown that on a national basis about 2/3 of the nitrate leaching from the root zone is reduced naturally, through denitrification, in the subsurface before reaching the streams. Therefore, it is more cost-effective to identify robust areas, where nitrate leaching through the root...... the entire catchment. However, as distributed models often do not include local scale hydrogeological heterogeneities, they are typically not able to make accurate predictions at scales smaller than they are calibrated. We present a framework for assessing nitrate reduction in the subsurface...

  11. ROE Wet Nitrate Deposition 1989-1991

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet nitrate deposition in kilograms per hectare from 1989 to 1991. Summary data in this indicator were provided by EPA’s...

  12. ROE Wet Nitrate Deposition 2011-2013

    Data.gov (United States)

    U.S. Environmental Protection Agency — The raster data represent the amount of wet nitrate deposition in kilograms per hectare from 2011 to 2013. Summary data in this indicator were provided by EPA’s...

  13. 77 FR 65532 - Solid Fertilizer Grade Ammonium Nitrate From the Russian Federation: Notice of Rescission of...

    Science.gov (United States)

    2012-10-29

    ... International Trade Administration Solid Fertilizer Grade Ammonium Nitrate From the Russian Federation: Notice... the antidumping duty order on solid fertilizer grade ammonium nitrate (ammonium nitrate) from the... Administrative Review: Solid Fertilizer Grade Ammonium Nitrate (Ammonium Nitrate) from the Russian...

  14. Calcium contributes to photoprotection and repair of photosystem II in peanut leaves during heat and high irradiance

    Institute of Scientific and Technical Information of China (English)

    Sha Yang; Fang Wang; Feng Guo; Jing-Jing Meng; Xin-Guo Li; Shu-Bo Wan

    2015-01-01

    In this study, we investigated the effects of exogenous calcium nitrate on photoinhibition and thylakoid protein level in peanut plants under heat (40 °C) and high irradiance (HI) (1,200 mmol/m2 per s) stress. Compared with control seedlings (cultivated in 0 mmol/L Ca(NO3)2 medium), the maximal photochemical efficiency of photosystem II (PSII) in Ca2þ‐treated plants showed a slight decrease after 5 h stress, accompanied by lower degree of PSII closure (1‐qP), higher non‐photochemical quenching, and lower level of membrane damage. Ca2þ inhibitors were used to analyze the varieties of antioxidant enzymes activity and PSII proteins. These results indicated that Ca2þ could protect the subunits of PSII reaction centers from photoinhibition by reducing the generation of reactive oxygen species. In the presence of both ethyleneglycol‐bis(2‐aminoethylether)‐tetraacetic acid and ascorbic acid (AsA), the net degradation of the damaged D1 protein was faster than that only treated with AsA. Our previous study showed that either the transcriptional or the translational level of calmodulin was obviously higher in Ca2þ‐treated plants. These results suggested that, under heat and HI stress, the Ca2þ signal transduction pathway can al eviate the photoinhibition through regulating the protein repair process besides an enhanced capacity for scavenging reactive oxygen species.

  15. Effectiveness of inhibitors in increasing chloride threshold value for steel corrosion

    Directory of Open Access Journals (Sweden)

    Jin-xia XU

    2013-07-01

    Full Text Available This investigation was aimed at evaluating the effectiveness of corrosion inhibitors in increasing the chloride threshold value for steel corrosion. Three types of corrosion inhibitors, calcium nitrite (Ca(NO22, zinc oxide (ZnO, and N,N'-dimethylaminoethanol (DMEA, which respectively represented the anodic inhibitor, cathodic inhibitor, and mixed inhibitor, were chosen. The experiment was carried out in a saturated calcium hydroxide (Ca(OH2 solution to simulate the electrolytic environment of concrete. The inhibitors were initially mixed at different levels, and then chloride ions were gradually added into the solution in several steps. The open-circuit potential (Ecorr and corrosion current density (Icorr determined by electrochemical impedance spectra (EIS were used to identify the initiation of active corrosion, thereby determining the chloride threshold value. It was found that although all the inhibitors were effective in decreasing the corrosion rate of steel reinforcement, they had a marginal effect on increasing the chloride threshold value.

  16. Preformed Nitrate in the Glacial North Atlantic

    Science.gov (United States)

    Homola, K.; Spivack, A. J.; D'Hondt, S.; Estes, E. R.; Insua, T. L.; McKinley, C. C.; Murray, R. W.; Pockalny, R. A.; Robinson, R. S.; Sauvage, J.

    2015-12-01

    Atmospheric CO2 abundances are highly correlated with global temperature variations over the past 800,000 years. Consequently, understanding the feedbacks between climate and CO2 is important for predictions of future climate. Leading hypotheses to explain this feedback invoke changes in ocean biology, circulation, chemistry, and/or gas exchange rates to trap CO2 in the deep ocean, thereby reducing the greenhouse effect of CO2 in the atmosphere. To test these hypotheses, we use sediment pore water profiles of dissolved nitrate and oxygen to reconstruct paleo-preformed nitrate concentrations at two deep-water sites in the western North Atlantic (23°N 57°W, 5557 m water depth; 30°N 58°W, 5367 m water depth). Preformed nitrate increases down-core to 22.7 μM (25.6 m core depth) at the northern site, and to 28.5 μM (27.8 m core depth) at the southern site. The large preformed nitrate gradient between these sites reveals a paleo-boundary between a southern water source high in preformed nitrate and a northern water source with lower concentrations, similar to today's ocean. However, the boundary between these water masses occurs north of where their modern counterparts meet, indicating that Antarctic Bottom Water (AABW) extended farther north during the Last Glacial Maximum (LGM). In addition, the southern source had a higher preformed nitrate concentration than today's AABW (25 μM), contradicting hypotheses that nutrient utilization was more efficient in the Southern Ocean deep-water formation regions during the LGM. Comparison to our previous Pacific data reveals that the average preformed nitrate concentration of the deep ocean was slightly higher during the LGM than today. This result implies that the CO2-climate feedback was not principally due to more efficient nitrate utilization.

  17. Is beetroot juice more effective than sodium nitrate? The effects of equimolar nitrate dosages of nitrate-rich beetroot juice and sodium nitrate on oxygen consumption during exercise.

    Science.gov (United States)

    Flueck, Joelle Leonie; Bogdanova, Anna; Mettler, Samuel; Perret, Claudio

    2016-04-01

    Dietary nitrate has been reported to lower oxygen consumption in moderate- and severe-intensity exercise. To date, it is unproven that sodium nitrate (NaNO3(-); NIT) and nitrate-rich beetroot juice (BR) have the same effects on oxygen consumption, blood pressure, and plasma nitrate and nitrite concentrations or not. The aim of this study was to compare the effects of different dosages of NIT and BR on oxygen consumption in male athletes. Twelve healthy, well-trained men (median [minimum; maximum]; peak oxygen consumption: 59.4 mL·min(-1)·kg(-1) [40.5; 67.0]) performed 7 trials on different days, ingesting different nitrate dosages and placebo (PLC). Dosages were 3, 6, and 12 mmol nitrate as concentrated BR or NIT dissolved in plain water. Plasma nitrate and nitrite concentrations were measured before, 3 h after ingestion, and postexercise. Participants cycled for 5 min at moderate intensity and further 8 min at severe intensity. End-exercise oxygen consumption at moderate intensity was not significantly different between the 7 trials (p = 0.08). At severe-intensity exercise, end-exercise oxygen consumption was ~4% lower in the 6-mmol BR trial compared with the 6-mmol NIT (p = 0.003) trial as well as compared with PLC (p = 0.010). Plasma nitrite and nitrate concentrations were significantly increased after the ingestion of BR and NIT with the highest concentrations in the 12-mmol trials. Plasma nitrite concentration between NIT and BR did not significantly differ in the 6-mmol (p = 0.27) and in the 12-mmol (p = 0.75) trials. In conclusion, BR might reduce oxygen consumption to a greater extent compared with NIT.

  18. Synthesis of a new energetic nitrate ester

    Energy Technology Data Exchange (ETDEWEB)

    Chavez, David E [Los Alamos National Laboratory

    2008-01-01

    Nitrate esters have been known as useful energetic materials since the discovery of nitroglycerin by Ascanio Sobrero in 1846. The development of methods to increase the safety and utility of nitroglycerin by Alfred Nobel led to the revolutionary improvement in the utility of nitroglycerin in explosive applications in the form of dynamite. Since then, many nitrate esters have been prepared and incorporated into military applications such as double-based propellants, detonators and as energetic plasticizers. Nitrate esters have also been shown to have vasodilatory effects in humans and thus have been studied and used for treatments of ailments such as angina. The mechanism of the biological response towards nitrate esters has been elucidated recently. Interestingly, many of the nitrate esters used for military purposes are liquids (ethylene glycol dinitrate, propylene glycol dinitrate, etc). Pentaerythritol tetranitrate (PETN) is one of the only solid nitrate esters, besides nitrocellulose, that is used in any application. Unfortunately, PETN melting point is above 100 {sup o}C, and thus must be pressed as a solid for detonator applications. A more practical material would be a melt-castable explosive, for potential simplification of manufacturing processes. Herein we describe the synthesis of a new energetic nitrate ester (1) that is a solid at ambient temperatures, has a melting point of 85-86 {sup o}C and has the highest density of any known nitrate ester composed only of carbon, hydrogen, nitrogen and oxygen. We also describe the chemical, thermal and sensitivity properties of 1 as well as some preliminary explosive performance data.

  19. The Arabidopsis ATNRT2.7 nitrate transporter controls nitrate content in seeds.

    Science.gov (United States)

    Chopin, Franck; Orsel, Mathilde; Dorbe, Marie-France; Chardon, Fabien; Truong, Hoai-Nam; Miller, Anthony J; Krapp, Anne; Daniel-Vedele, Françoise

    2007-05-01

    In higher plants, nitrate is taken up by root cells where Arabidopsis thaliana NITRATE TRANSPORTER2.1 (ATNRT2.1) chiefly acts as the high-affinity nitrate uptake system. Nitrate taken up by the roots can then be translocated from the root to the leaves and the seeds. In this work, the function of the ATNRT2.7 gene, one of the seven members of the NRT2 family in Arabidopsis, was investigated. High expression of the gene was detected in reproductive organs and peaked in dry seeds. beta-Glucuronidase or green fluorescent protein reporter gene expression driven by the ATNRT2.7 promoter confirmed this organ specificity. We assessed the capacity of ATNRT2.7 to transport nitrate in Xenopus laevis oocytes or when it is expressed ectopically in mutant plants deficient in nitrate transport. We measured the impact of an ATNRT2.7 mutation and found no difference from the wild type during vegetative development. By contrast, seed nitrate content was affected by overexpression of ATNRT2.7 or a mutation in the gene. Finally, we showed that this nitrate transporter protein was localized to the vacuolar membrane. Our results demonstrate that ATNRT2.7 plays a specific role in nitrate accumulation in the seed.

  20. Single step preparation of nanosilver loaded calcium phosphate by low temperature co-conversion process.

    Science.gov (United States)

    Suwanprateeb, J; Thammarakcharoen, F; Wasoontararat, K; Chokevivat, W; Phanphiriya, P

    2012-09-01

    The preparation and characterization of nanosilver loaded calcium phosphate aiming to enhance the bactericidal performance by a single step co-conversion technique using low temperature ion exchange phosphorization in combination with Tollen's reaction were performed. Silver nitrate was used as a silver ion supply source (0.001-0.1 M) and glucose was employed as a reducing agent. After conversion, surface and shell zones of all samples comprised hydroxyapatite and metallic silver as the main phases regardless of silver nitrate concentration. However, hydroxyapatite, residual calcium sulfate and monetite were found in the core zone when using silver nitrate concentration lower than 0.1 M. The microstructure of all samples comprised the distribution of spherical-shaped silver nanoparticles within the cluster of calcium phosphate nanocrystals. Total silver content (range, 0.09-6.5 %) in the converted samples was found to linearly increase with increasing silver nitrate content. Flexural modulus and strength of converted samples generally decreased with increasing silver content. Effective antibacterial activity of two selected samples (0.001 and 0.005 M AgNO(3)) against two bacterial strains (Pseudomonas aeruginosa and Staphylococcus aureus) was observed. Cytotoxic potentials by MTT assay of both samples were observed at 24 and 48 h extraction respectively.

  1. Reactivity of nitrate and organic acids at the concrete–bitumen interface of a nuclear waste repository cell

    Energy Technology Data Exchange (ETDEWEB)

    Bertron, A., E-mail: bertron@insa-toulouse.fr [Université de Toulouse (France); UPS, INSA (France); LMDC (Laboratoire Matériaux et Durabilité des Constructions), 135, avenue de Rangueil, F-31 077, Toulouse Cedex 04 (France); Jacquemet, N. [Université de Toulouse (France); UPS, INSA (France); LMDC (Laboratoire Matériaux et Durabilité des Constructions), 135, avenue de Rangueil, F-31 077, Toulouse Cedex 04 (France); Erable, B. [Université de Toulouse (France); INPT, UPS (France); CNRS, Laboratoire de Génie Chimique, 4, Allée Emile Monso, F-31030 Toulouse (France); Sablayrolles, C. [Université de Toulouse (France); INP (France); LCA (Laboratoire de Chimie Agro-Industrielle), ENSIACET, 4 allée Emile Monso, BP 44 362, 31432 Toulouse Cedex 4 (France); INRA (France); LCA (Laboratoire de Chimie Agro-Industrielle), F-31029 Toulouse (France); Escadeillas, G. [Université de Toulouse (France); UPS, INSA (France); LMDC (Laboratoire Matériaux et Durabilité des Constructions), 135, avenue de Rangueil, F-31 077, Toulouse Cedex 04 (France); Albrecht, A. [Andra, 1-7, rue Jean-Monnet, 92298 Châtenay-Malabry (France)

    2014-03-01

    Highlights: • Interactions of cement paste and organic acid–nitrate solutions were investigated. • Cement leaching imposed alkaline pH (>10) very rapidly in the liquid media. • Acetic acid action on cement paste was similar to that of classical leaching. • Oxalic acid attack formed Ca-oxalate salts; organic matter in solution decreased. • Nitrate was stable under abiotic conditions and with organic matter. - Abstract: This study investigates the fate of nitrate and organic acids at the bitumen–concrete interface within repository cell for long-lived, intermediate-level, radioactive wastes. The interface was simulated by a multiphase system in which cementitious matrices (CEM V cement paste specimens) were exposed to bitumen model leachates consisting of nitrates and acetic acid with and without oxalic acid, chemical compounds likely to be released by bitumen. Leaching experiments were conducted with daily renewal of the solutions in order to accelerate reactions. The concentrations of anions (acetate, oxalate, nitrate, and nitrite) and cations (calcium, potassium) and the pH were monitored over time. Mineralogical changes of the cementitious matrices were analysed by XRD. The results confirmed the stability of nitrates in the abiotic conditions of the experiments. The action of acetic acid on the cementitious matrix was similar to that of ordinary leaching in the absence of organic acids (i.e. carried out with water or strong acids); no specific interaction was detected between acetate and cementitious cations. The reaction of oxalic acid with the cementitious phases led to the precipitation of calcium oxalate salts in the outer layer of the matrix. The concentration of oxalate was reduced by 65% inside the leaching medium.

  2. Calcium channel blockers in cardiovascular pharmacotherapy.

    Science.gov (United States)

    Godfraind, Theophile

    2014-11-01

    This paper summarizes the pharmacological properties of calcium channel blockers (CCBs), their established therapeutic uses for cardiovascular disorders and the current improvement of their clinical effects through drug combinations. Their identification resulted from study of small molecules including coronary dilators, which were named calcium antagonists. Further experiments showed that they reduced contraction of arteries by inhibiting calcium entry and by interacting with binding sites identified on voltage-dependent calcium channels. This led to the denomination calcium channel blockers. In short-term studies, by decreasing total peripheral resistance, CCBs lower arterial pressure. By unloading the heart and increasing coronary blood flow, CCBs improve myocardial oxygenation. In long-term treatment, the decrease in blood pressure is more pronounced in hypertensive than in normotensive patients. A controversy on the safety of CCBs ended after a large antihypertensive trial (ALLHAT) sponsored by the National Heart, Lung, and Blood Institute. There are two main types of CCBs: dihydopyridine and non-dihydropyridine; the first type is vascular selective. Dihydropyrines are indicated for hypertension, chronic, stable and vasospastic angina. Non-dihydropyridines have the same indications plus antiarrythmic effects in atrial fibrillation or flutter and paroxysmal supraventricular tachycardia. In addition, CCBs reduced newly formed coronary lesions in atherosclerosis. In order to reach recommended blood pressure goals, there is a recent therapeutic move by combination of CCBs with other antihypertensive agents particularly with inhibitors acting at the level of the renin-angiotensin system. They are also combined with statins. Prevention of dementia has been reported in hypertensive patients treated with nitrendipine, opening a way for further studies on CCBs' beneficial effect in cognitive deterioration associated with aging.

  3. Stimulating nitrate removal processes of restored wetlands.

    Science.gov (United States)

    Ballantine, Kate A; Groffman, Peter M; Lehmann, Johannes; Schneider, Rebecca L

    2014-07-01

    The environmental and health effects caused by nitrate contamination of aquatic systems are a serious problem throughout the world. A strategy proposed to address nitrate pollution is the restoration of wetlands. However, although natural wetlands often remove nitrate via high rates of denitrification, wetlands restored for water quality functions often fall below expectations. This may be in part because key drivers for denitrification, in particular soil carbon, are slow to develop in restored wetlands. We added organic soil amendments that range along a gradient of carbon lability to four newly restored wetlands in western New York to investigate the effect of carbon additions on denitrification and other processes of the nitrogen cycle. Soil carbon increased by 12.67-63.30% with the use of soil amendments (p ≤ 0.0001). Soil nitrate, the carbon to nitrogen ratio, and microbial biomass nitrogen were the most significant predictors of denitrification potential. Denitrification potential, potential net nitrogen nitrification and mineralization, and soil nitrate and ammonium, were highest in topsoil-amended plots, with increases in denitrification potential of 161.27% over control plots. While amendment with topsoil more than doubled several key nitrogen cycling processes, more research is required to determine what type and level of amendment application are most effective for stimulating removal of exogenous nitrate and meeting functional goals within an acceptable time frame.

  4. Nitrate Adsorption on Clay Kaolin: Batch Tests

    Directory of Open Access Journals (Sweden)

    Morteza Mohsenipour

    2015-01-01

    Full Text Available Soils possessing kaolin, gibbsite, goethite, and hematite particles have been found to have a natural capacity to attenuate pollution in aqueous phase. On the other hand, the hydroxyl group in soil increases anion exchange capacity under a low pH condition. The main objective of this paper was to evaluate effects of kaolin on nitrate reduction under acidic condition. In order to analyze the kaolin adsorption behaviour under various conditions, four different concentrations of nitrate, 45, 112.5, 225, and 450 mgNO3-/L, with a constant pH equal to 2, constant temperature equal to 25°C, and exposure period varying from 0 to 150 minutes were considered. The capacity of nitrate adsorption on kaolin has also been studied involving two well-known adsorption isotherm models, namely, Freundlich and Longmuir. The results revealed that approximately 25% of the nitrate present in the solution was adsorbed on clay kaolin. The laboratory experimental data revealed that Freundlich adsorption isotherm model was more accurate than Longmuir adsorption model in predicting of nitrate adsorption. Furthermore, the retardation factor of nitrate pollution in saturated zone has been found to be approximately 4 in presence of kaolin, which indicated that kaolin can be used for natural scavenger of pollution in the environment.

  5. Calcium in plant cells

    Directory of Open Access Journals (Sweden)

    V. V. Schwartau

    2014-04-01

    Full Text Available The paper gives the review on the role of calcium in many physiological processes of plant organisms, including growth and development, protection from pathogenic influences, response to changing environmental factors, and many other aspects of plant physiology. Initial intake of calcium ions is carried out by Ca2+-channels of plasma membrane and they are further transported by the xylem owing to auxins’ attractive ability. The level of intake and selectivity of calcium transport to ove-ground parts of the plant is controlled by a symplast. Ca2+enters to the cytoplasm of endoderm cells through calcium channels on the cortical side of Kaspary bands, and is redistributed inside the stele by the symplast, with the use of Ca2+-АТPases and Ca2+/Н+-antiports. Owing to regulated expression and activity of these calcium transporters, calclum can be selectively delivered to the xylem. Important role in supporting calcium homeostasis is given to the vacuole which is the largest depo of calcium. Regulated quantity of calcium movement through the tonoplast is provided by a number of potential-, ligand-gated active transporters and channels, like Ca2+-ATPase and Ca2+/H+ exchanger. They are actively involved in the inactivation of the calcium signal by pumping Ca2+ to the depo of cells. Calcium ATPases are high affinity pumps that efficiently transfer calcium ions against the concentration gradient in their presence in the solution in nanomolar concentrations. Calcium exchangers are low affinity, high capacity Ca2+ transporters that are effectively transporting calcium after raising its concentration in the cell cytosol through the use of protons gradients. Maintaining constant concentration and participation in the response to stimuli of different types also involves EPR, plastids, mitochondria, and cell wall. Calcium binding proteins contain several conserved sequences that provide sensitivity to changes in the concentration of Ca2+ and when you

  6. Both plant and bacterial nitrate reductases contribute to nitric oxide production in Medicago truncatula nitrogen-fixing nodules.

    Science.gov (United States)

    Horchani, Faouzi; Prévot, Marianne; Boscari, Alexandre; Evangelisti, Edouard; Meilhoc, Eliane; Bruand, Claude; Raymond, Philippe; Boncompagni, Eric; Aschi-Smiti, Samira; Puppo, Alain; Brouquisse, Renaud

    2011-02-01

    Nitric oxide (NO) is a signaling and defense molecule of major importance in living organisms. In the model legume Medicago truncatula, NO production has been detected in the nitrogen fixation zone of the nodule, but the systems responsible for its synthesis are yet unknown and its role in symbiosis is far from being elucidated. In this work, using pharmacological and genetic approaches, we explored the enzymatic source of NO production in M. truncatula-Sinorhizobium meliloti nodules under normoxic and hypoxic conditions. When transferred from normoxia to hypoxia, nodule NO production was rapidly increased, indicating that NO production capacity is present in functioning nodules and may be promptly up-regulated in response to decreased oxygen availability. Contrary to roots and leaves, nodule NO production was stimulated by nitrate and nitrite and inhibited by tungstate, a nitrate reductase inhibitor. Nodules obtained with either plant nitrate reductase RNA interference double knockdown (MtNR1/2) or bacterial nitrate reductase-deficient (napA) and nitrite reductase-deficient (nirK) mutants, or both, exhibited reduced nitrate or nitrite reductase activities and NO production levels. Moreover, NO production in nodules was found to be inhibited by electron transfer chain inhibitors, and nodule energy state (ATP-ADP ratio) was significantly reduced when nodules were incubated in the presence of tungstate. Our data indicate that both plant and bacterial nitrate reductase and electron transfer chains are involved in NO synthesis. We propose the existence of a nitrate-NO respiration process in nodules that could play a role in the maintenance of the energy status required for nitrogen fixation under oxygen-limiting conditions.

  7. Elemental calcium intake associated with calcium acetate/calcium carbonate in the treatment of hyperphosphatemia

    OpenAIRE

    Wilson, Rosamund J; Copley, J Brian

    2017-01-01

    Background Calcium-based and non-calcium-based phosphate binders have similar efficacy in the treatment of hyperphosphatemia; however, calcium-based binders may be associated with hypercalcemia, vascular calcification, and adynamic bone disease. Scope A post hoc analysis was carried out of data from a 16-week, Phase IV study of patients with end-stage renal disease (ESRD) who switched to lanthanum carbonate monotherapy from baseline calcium acetate/calcium carbonate monotherapy. Of the intent...

  8. [Microbial geochemical calcium cycle].

    Science.gov (United States)

    Zavarzin, G A

    2002-01-01

    The participation of microorganisms in the geochemical calcium cycle is the most important factor maintaining neutral conditions on the Earth. This cycle has profound influence on the fate of inorganic carbon, and, thereby, on the removal of CO2 from the atmosphere. The major part of calcium deposits was formed in the Precambrian, when prokaryotic biosphere predominated. After that, calcium recycling based on biogenic deposition by skeletal organisms became the main process. Among prokaryotes, only a few representatives, e.g., cyanobacteria, exhibit a special calcium function. The geochemical calcium cycle is made possible by the universal features of bacteria involved in biologically mediated reactions and is determined by the activities of microbial communities. In the prokaryotic system, the calcium cycle begins with the leaching of igneous rock predominantly through the action of the community of organotrophic organisms. The release of carbon dioxide to the soil air by organotrophic aerobes leads to leaching with carbonic acid and soda salinization. Under anoxic conditions, of major importance is the organic acid production by primary anaerobes (fermentative microorganisms). Calcium carbonate is precipitated by secondary anaerobes (sulfate reducers) and to a smaller degree by methanogens. The role of the cyanobacterial community in carbonate deposition is exposed by stromatolites, which are the most common organo-sedimentary Precambrian structures. Deposition of carbonates in cyanobacterial mats as a consequence of photoassimilation of CO2 does not appear to be a significant process. It is argued that carbonates were deposited at the boundary between the "soda continent", which emerged as a result of subaerial leaching with carbonic acid, and the ocean containing Ca2+. Such ecotones provided favorable conditions for the development of the benthic cyanobacterial community, which was a precursor of stromatolites.

  9. ANTITHROMBOTIC THERAPY OF ISCHEMIC HEART DISEASE: FROM FAST ACTING ANTIAGGREGANTS TO STATINES AND NITRATE OXIDE. IS IT REAL?

    Directory of Open Access Journals (Sweden)

    I. A. Latfullin

    2006-01-01

    Full Text Available Mechanisms of atherothrombosis in atherosclerosis of coronary arteries are described. Mechanism of action and clinical efficiency of antithrombotic and antiplatelet medicines such as acetylsalicylic acid, warfarin, ticlopidine and clopidogrel are discussed. Study data on new antiplatelet drugs are given: selective thromboxane inhibitors, antagonists of thromboxane receptors, blockers of platelet receptors for glycoproteins GPIIb/IIIa. Possibility of clinical use of additional antiplatelet features of statines is discussed, as well as their connection to stimulation of nitrate oxide production, powerful endogenous antiplatelet factor. Examples of other donators of nitrate oxide and activators of its endogenous synthesis are given.

  10. Side effects of using nitrates to treat heart failure and the acute coronary syndromes, unstable angina and acute myocardial infarction.

    Science.gov (United States)

    Thadani, Udho; Ripley, Toni L

    2007-07-01

    Nitrates are potent venous dilators and anti-ischemic agents. They are widely used for the relief of chest pain and pulmonary congestion in patients with acute coronary syndromes and heart failure. Nitrates, however, do not reduce mortality in patients with acute coronary syndromes. Combination of nitrates and hydralazine when given in addition to beta-blockers and angiotensin-converting enzyme (ACE) inhibitors reduce mortality and heart failure hospitalizations in patients with heart failure due to left ventricular systolic dysfunction who are of African-American origin. Side effects during nitrate therapy are common but are less well described in the literature compared with the reported side effects in patients with stable angina pectoris. The reported incidence of side effects varies highly among different studies and among various disease states. Headache is the most commonly reported side effect with an incidence of 12% in acute heart failure, 41-73% in chronic heart failure, 3-19% in unstable angina and 2-26% in acute myocardial infarction. The reported incidence of hypotension also differs: 5-10% in acute heart failure, 20% in chronic heart failure, 9% in unstable angina and < 1-48% in acute myocardial infarction, with the incidence being much higher with concomitant nitrate therapy plus angiotensin-converting enzyme inhibitors. Reported incidence of dizziness is as low as 1% in patients with acute myocardial infarction to as high as 29% in patients with heart failure. Severe headaches and/or symptomatic hypotension may necessitate discontinuation of nitrate therapy. Severe life threatening hypotension or even death may occur when nitrates are used in patients with acute inferior myocardial infarction associated with right ventricular dysfunction or infarction, or with concomitant use of phosphodiesterase-5 inhibitors or N-acetylcysteine. Despite the disturbing observational reports in the literature that continuous and prolonged use of nitrates may lead to

  11. Historical Tracking of Nitrate in Contrasting Vineyard Using Water Isotopes and Nitrate Depth Profiles

    Science.gov (United States)

    Sprenger, M.; Erhardt, M.; Riedel, M.; Weiler, M.

    2015-12-01

    The European Water Framework Directive (EWFD) aims to achieve a good chemical status for the groundwater bodies in Europe by the year 2015. Despite the effort to reduce the nitrate pollution from agriculture within the last two decades, there are still many groundwater aquifers that exceed nitrate concentrations above the EWFD threshold of 50 mg/l. Viticulture is seen as a major contributor of nitrate leaching and sowing of a green cover was shown to have a positive effect on lowering the nitrate loads in the upper 90 cm of the soil. However, the consequences for nitrate leaching into the subsoil were not yet tested. We analyzed the nitrate concentrations and pore water stable isotope composition to a depth of 380 cm in soil profiles under an old vineyard and a young vineyard with either soil tillage or permanent green cover in between the grapevines. The pore water stable isotopes were used to calibrate a soil physical model, which was then used to infer the age of the soil water at different depths. This way, we could relate elevated nitrate concentrations below an old vineyard to tillage processes that took place during the winter two years before the sampling. We further showed that the elevated nitrate concentration in the subsoil of a young vineyard can be related to the soil tillage prior to the planting of the new vineyard. If the soil is kept bare due to tillage, a nitrate concentration of 200 kg NO3--N/ha is found in 290 to 380 cm depth 2.5 years after the installation of the vineyard. The amount of nitrate leaching is considerably reduced due to a seeded green cover between the grapevines that takes up a high share of the mobilized nitrate reducing a potential contamination of the groundwater.

  12. Effect of dietary nitrate level on enteric methane production, hydrogen emission, rumen fermentation, and nutrient digestibility in dairy cows.

    Science.gov (United States)

    Olijhoek, D W; Hellwing, A L F; Brask, M; Weisbjerg, M R; Højberg, O; Larsen, M K; Dijkstra, J; Erlandsen, E J; Lund, P

    2016-08-01

    Nitrate may lower methane production in ruminants by competing with methanogenesis for available hydrogen in the rumen. This study evaluated the effect of 4 levels of dietary nitrate addition on enteric methane production, hydrogen emission, feed intake, rumen fermentation, nutrient digestibility, microbial protein synthesis, and blood methemoglobin. In a 4×4 Latin square design 4 lactating Danish Holstein dairy cows fitted with rumen, duodenal, and ileal cannulas were assigned to 4 calcium ammonium nitrate addition levels: control, low, medium, and high [0, 5.3, 13.6, and 21.1g of nitrate/kg of dry matter (DM), respectively]. Diets were made isonitrogenous by replacing urea. Cows were fed ad libitum and, after a 6-d period of gradual introduction of nitrate, adapted to the corn-silage-based total mixed ration (forage:concentrate ratio 50:50 on DM basis) for 16d before sampling. Digesta content from duodenum, ileum, and feces, and rumen liquid were collected, after which methane production and hydrogen emissions were measured in respiration chambers. Methane production [L/kg of dry matter intake (DMI)] linearly decreased with increasing nitrate concentrations compared with the control, corresponding to a reduction of 6, 13, and 23% for the low, medium, and high diets, respectively. Methane production was lowered with apparent efficiencies (measured methane reduction relative to potential methane reduction) of 82.3, 71.9, and 79.4% for the low, medium, and high diets, respectively. Addition of nitrate increased hydrogen emissions (L/kg of DMI) quadratically by a factor of 2.5, 3.4, and 3.0 (as L/kg of DMI) for the low, medium, and high diets, respectively, compared with the control. Blood methemoglobin levels and nitrate concentrations in milk and urine increased with increasing nitrate intake, but did not constitute a threat for animal health and human food safety. Microbial crude protein synthesis and efficiency were unaffected. Total volatile fatty acid

  13. Inhibition of the Crystal Growth and Aggregation of Calcium Oxalate by Algae Sulfated Polysaccharide In-vitro

    Institute of Scientific and Technical Information of China (English)

    Xiu Mei WU; Jian Ming OUYANG; Sui Ping DENG; Ying Zhou CEN

    2006-01-01

    The influence of sulfated polysaccharide (SPS) isolated from marine algae Sargassum fusiforme on the morphology and phase compositions of urinary crystal calcium oxalate was investigated in vitro by means of scanning electron microscopy and X-ray diffraction. SPS maybe is a potential inhibitor to CaOxa urinary stones by inhibiting the growth of calcium oxalate monohydrate (COM), preventing the aggregation of COM, and inducing the formation of calcium oxalate dihydrate (COD) crystals.

  14. Calcium signaling mediates cold sensing in insect tissues.

    Science.gov (United States)

    Teets, Nicholas M; Yi, Shu-Xia; Lee, Richard E; Denlinger, David L

    2013-05-28

    The ability to rapidly respond to changes in temperature is a critical adaptation for insects and other ectotherms living in thermally variable environments. In a process called rapid cold hardening (RCH), insects significantly enhance cold tolerance following brief (i.e., minutes to hours) exposure to nonlethal chilling. Although the ecological relevance of RCH is well-established, the underlying physiological mechanisms that trigger RCH are poorly understood. RCH can be elicited in isolated tissues ex vivo, suggesting cold-sensing and downstream hardening pathways are governed by brain-independent signaling mechanisms. We previously provided preliminary evidence that calcium is involved in RCH, and here we firmly establish that calcium signaling mediates cold sensing in insect tissues. In tracheal cells of the freeze-tolerant goldenrod gall fly, Eurosta solidaginis, chilling to 0 °C evoked a 40% increase in intracellular calcium concentration as determined by live-cell confocal imaging. Downstream of calcium entry, RCH conditions significantly increased the activity of calcium/calmodulin-dependent protein kinase II (CaMKII) while reducing phosphorylation of the inhibitory Thr306 residue. Pharmacological inhibitors of calcium entry, calmodulin activation, and CaMKII activity all prevented ex vivo RCH in midgut and salivary gland tissues, indicating that calcium signaling is required for RCH to occur. Similar results were obtained for a freeze-intolerant species, adults of the flesh fly, Sarcophaga bullata, suggesting that calcium-mediated cold sensing is a general feature of insects. Our results imply that insect tissues use calcium signaling to instantly detect decreases in temperature and trigger downstream cold-hardening mechanisms.

  15. Nitrate in aquifers beneath agricultural systems.

    Science.gov (United States)

    Burkart, M R; Stoner, J D

    2007-01-01

    Research from several regions of the world provides spatially anecdotal evidence to hypothesize which hydrologic and agricultural factors contribute to groundwater vulnerability to nitrate contamination. Analysis of nationally consistent measurements from the U.S. Geological Survey's NAWQA program confirms these hypotheses for a substantial range of agricultural systems. Shallow unconfined aquifers are most susceptible to nitrate contamination associated with agricultural systems. Alluvial and other unconsolidated aquifers are the most vulnerable and also shallow carbonate aquifers that provide a substantial but smaller contamination risk. Where any of these aquifers are overlain by permeable soils the risk of contamination is larger. Irrigated systems can compound this vulnerability by increasing leaching facilitated by additional recharge and additional nutrient applications. The system of corn, soybean, and hogs produced significantly larger concentrations of groundwater nitrate than all other agricultural systems because this system imports the largest amount of N-fertilizer per unit production area. Mean nitrate under dairy, poultry, horticulture, and cattle and grains systems were similar. If trends in the relation between increased fertilizer use and groundwater nitrate in the United States are repeated in other regions of the world, Asia may experience increasing problems because of recent increases in fertilizer use. Groundwater monitoring in Western and Eastern Europe as well as Russia over the next decade may provide data to determine if the trend in increased nitrate contamination can be reversed. If the concentrated livestock trend in the United States is global, it may be accompanied by increasing nitrogen contamination in groundwater. Concentrated livestock provide both point sources in the confinement area and intense non-point sources as fields close to facilities are used for manure disposal. Regions where irrigated cropland is expanding, such as

  16. Inositol trisphosphate and calcium signalling

    Science.gov (United States)

    Berridge, Michael J.

    1993-01-01

    Inositol trisphosphate is a second messenger that controls many cellular processes by generating internal calcium signals. It operates through receptors whose molecular and physiological properties closely resemble the calcium-mobilizing ryanodine receptors of muscle. This family of intracellular calcium channels displays the regenerative process of calcium-induced calcium release responsible for the complex spatiotemporal patterns of calcium waves and oscillations. Such a dynamic signalling pathway controls many cellular processes, including fertilization, cell growth, transformation, secretion, smooth muscle contraction, sensory perception and neuronal signalling.

  17. Observations of Alkyl Nitrates during ARCTAS: Investigation of the low NOx Chemistry of Isoprene Nitrates

    Science.gov (United States)

    Browne, E. C.; Cohen, R. C.; Wooldridge, P. J.; Min, K.; Apel, E. C.; Blake, D. R.; Brune, W. H.; Fried, A.; Ren, X.; Weinheimer, A. J.; Wisthaler, A.; Team, A. S.

    2009-12-01

    During numerous ground and airborne experiments alkyl and multifunctional nitrates, measured by Thermal Dissociation-Laser Induced Fluorescence, have been shown to represent a significant fraction of oxidized nitrogen. It is postulated that a large fraction of these nitrates, particularly in forested environments, are isoprene-derived nitrates. The formation of these nitrates is important in terminating photochemical ozone production. However, it is still highly uncertain if these nitrates serve as a permanent termination step or only as a temporary sink that upon further oxidation, releases NO2 back into the atmosphere. The summer portion of the NASA ARCTAS experiment allows us to investigate the role of alkyl nitrates in photochemical ozone production in a new regime: the low NOx of the summer boreal forest. This data set also represents the first time that vertical profiles of the isoprene oxidation products methyl vinyl ketone and methacrolein were obtained along with total alkyl nitrates. We use these measurements to investigate and constrain the low NOx chemistry of isoprene nitrates. We compare these measurements to past airborne and laboratory studies.

  18. Nitrate removal from high strength nitrate-bearing wastes in granular sludge sequencing batch reactors.

    Science.gov (United States)

    Krishna Mohan, Tulasi Venkata; Renu, Kadali; Nancharaiah, Yarlagadda Venkata; Satya Sai, Pedapati Murali; Venugopalan, Vayalam Purath

    2016-02-01

    A 6-L sequencing batch reactor (SBR) was operated for development of granular sludge capable of denitrification of high strength nitrates. Complete and stable denitrification of up to 5420 mg L(-1) nitrate-N (2710 mg L(-1) nitrate-N in reactor) was achieved by feeding simulated nitrate waste at a C/N ratio of 3. Compact and dense denitrifying granular sludge with relatively stable microbial community was developed during reactor operation. Accumulation of large amounts of nitrite due to incomplete denitrification occurred when the SBR was fed with 5420 mg L(-1) NO3-N at a C/N ratio of 2. Complete denitrification could not be achieved at this C/N ratio, even after one week of reactor operation as the nitrite levels continued to accumulate. In order to improve denitrification performance, the reactor was fed with nitrate concentrations of 1354 mg L(-1), while keeping C/N ratio at 2. Subsequently, nitrate concentration in the feed was increased in a step-wise manner to establish complete denitrification of 5420 mg L(-1) NO3-N at a C/N ratio of 2. The results show that substrate concentration plays an important role in denitrification of high strength nitrate by influencing nitrite accumulation. Complete denitrification of high strength nitrates can be achieved at lower substrate concentrations, by an appropriate acclimatization strategy.

  19. Gravimetric Determination of Calcium as Calcium Carbonate Hydrate.

    Science.gov (United States)

    Henrickson, Charles H.; Robinson, Paul R.

    1979-01-01

    The gravimetric determination of calcium as calcium carbonate is described. This experiment is suitable for undergraduate quantitative analysis laboratories. It is less expensive than determination of chloride as silver chloride. (BB)

  20. Calcium and Calcium Supplements: Achieving the Right Balance

    Science.gov (United States)

    ... bone mass, which is a risk factor for osteoporosis. Many Americans don't get enough calcium in their diets. Children and adolescent girls are at particular risk, but so are adults age 50 and older. How much calcium you ...

  1. Mitochondrial calcium uptake capacity modulates neocortical excitability.

    Science.gov (United States)

    Sanganahalli, Basavaraju G; Herman, Peter; Hyder, Fahmeed; Kannurpatti, Sridhar S

    2013-07-01

    Local calcium (Ca(2+)) changes regulate central nervous system metabolism and communication integrated by subcellular processes including mitochondrial Ca(2+) uptake. Mitochondria take up Ca(2+) through the calcium uniporter (mCU) aided by cytoplasmic microdomains of high Ca(2+). Known only in vitro, the in vivo impact of mCU activity may reveal Ca(2+)-mediated roles of mitochondria in brain signaling and metabolism. From in vitro studies of mitochondrial Ca(2+) sequestration and cycling in various cell types of the central nervous system, we evaluated ranges of spontaneous and activity-induced Ca(2+) distributions in multiple subcellular compartments in vivo. We hypothesized that inhibiting (or enhancing) mCU activity would attenuate (or augment) cortical neuronal activity as well as activity-induced hemodynamic responses in an overall cytoplasmic and mitochondrial Ca(2+)-dependent manner. Spontaneous and sensory-evoked cortical activities were measured by extracellular electrophysiology complemented with dynamic mapping of blood oxygen level dependence and cerebral blood flow. Calcium uniporter activity was inhibited and enhanced pharmacologically, and its impact on the multimodal measures were analyzed in an integrated manner. Ru360, an mCU inhibitor, reduced all stimulus-evoked responses, whereas Kaempferol, an mCU enhancer, augmented all evoked responses. Collectively, the results confirm aforementioned hypotheses and support the Ca(2+) uptake-mediated integrative role of in vivo mitochondria on neocortical activity.

  2. Microbial Reduction of Chromate in the presence of Nitrate by Three Nitrate Respiring Organisms.

    Directory of Open Access Journals (Sweden)

    Peter eChovanec

    2012-12-01

    Full Text Available A major challenge for the bioremediation of toxic metals is the co-occurrence of nitrate, as it can inhibit metal transformation. Geobacter metallireducens, Desulfovibrio desulfuricans, and Sulfurospirillum barnesii are three soil bacteria that can reduce chromate (Cr(VI and nitrate, and may be beneficial for developing bioremediation strategies. All three organisms respire through dissimilatory nitrate reduction to ammonia (DNRA, employing different nitrate reductases but similar nitrite reductase (Nrf. G. metallireducens reduces nitrate to nitrite via the membrane bound nitrate reductase (Nar, while S. barnesii and D. desulfuricans strain 27774 have slightly different forms of periplasmic nitrate reductase (Nap. We investigated the effect of DNRA growth in the presence of Cr(VI in these three organisms and the ability of each to reduce Cr(VI to Cr(III, and each organisms responded differently. Growth of G. metallireducens on nitrate was completely inhibited by Cr(VI. Cultures of D. desulfuricans on nitrate media was initially delayed (48 h in the presence of Cr(VI, but ultimately reached comparable cell yields to the non-treated control. This prolonged lag phase accompanied the transformation of Cr(VI to Cr(III. Viable G. metallireducens cells could reduce Cr(VI, whereas Cr(VI reduction by D. desulfuricans during growth, was mediated by a filterable and heat stable extracellular metabolite. S. barnesii growth on nitrate was not affected by Cr(VI, and Cr(VI was reduced to Cr(III. However, Cr(VI reduction activity in S. barnesii, was detected in both the cell free spent medium and cells, indicating both extracellular and cell associated mechanisms. Taken together, these results have demonstrated that Cr(VI affects DNRA in the three organisms differently, and that each have a unique mechanism for Cr(VI reduction.

  3. Ion Pairing in Alkali Nitrate Electrolyte Solutions.

    Science.gov (United States)

    Xie, Wen Jun; Zhang, Zhen; Gao, Yi Qin

    2016-03-10

    In this study, we investigate the thermodynamics of alkali nitrate salt solutions, especially the formation of contact ion pairs between alkali cation and nitrate anion. The ion-pairing propensity shows an order of LiNO3 activity coefficients and suggest that the empirical "law of matching water affinity" is followed by these alkali nitrate salt solutions. The spatial patterns of contact ion pairs are different in the three salt solutions studied here: Li(+) forms the contact ion pair with only one oxygen of the nitrate while Na(+) and K(+) can also be shared by two oxygens of the nitrate. In reproducing the salt activity coefficient using Kirkwood-Buff theory, we find that it is essential to include electronic polarization for Li(+) which has a high charge density. The electronic continuum correction for nonpolarizable force field significantly improves the agreement between the calculated activity coefficients and their experimental values. This approach also improves the performance of the force field on salt solubility. From these two aspects, this study suggests that electronic continuum correction can be a promising approach to force-field development for ions with high charge densities.

  4. Nitrate transceptor(s) in plants.

    Science.gov (United States)

    Gojon, Alain; Krouk, Gabriel; Perrine-Walker, Francine; Laugier, Edith

    2011-04-01

    The availability of mineral nutrients in the soil dramatically fluctuates in both time and space. In order to optimize their nutrition, plants need efficient sensing systems that rapidly signal the local external concentrations of the individual nutrients. Until recently, the most upstream actors of the nutrient signalling pathways, i.e. the sensors/receptors that perceive the extracellular nutrients, were unknown. In Arabidopsis, increasing evidence suggests that, for nitrate, the main nitrogen source for most plant species, a major sensor is the NRT1.1 nitrate transporter, also contributing to nitrate uptake by the roots. Membrane proteins that fulfil a dual nutrient transport/signalling function have been described in yeast and animals, and are called 'transceptors'. This review aims to illustrate the nutrient transceptor concept in plants by presenting the current evidence indicating that NRT1.1 is a representative of this class of protein. The various facets, as well as the mechanisms of nitrate sensing by NRT1.1 are considered, and the possible occurrence of other nitrate transceptors is discussed.

  5. Synthesis of nanocrystalline calcium phosphate in microemulsion--effect of nature of surfactants.

    Science.gov (United States)

    Singh, Sujata; Bhardwaj, Pallavi; Singh, V; Aggarwal, S; Mandal, U K

    2008-03-01

    Nanosized calcium phosphate (CP) powders have been synthesized by an inverse microemulsion system using kerosene as the oil phase, a cationic surfactant Aliquat 336, a non-ionic surfactant Tween 20 and their mixture and aqueous solutions of calcium nitrate tetrahydrate and biammonium hydrogen phosphate as the water phase. It has been found that the nature of surfactants played an important role to regulate the size and morphologies of the calcium phosphate nanoparticles. The cationic surfactant Aliquat 336 has been found to regulate the nucleation and crystal growth. The synthesized powders have been comprehensively characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Our results show that the brushite (DCPD) is the major phase comprising the calcium phosphate nanoparticles. In mixed surfactants mediated system a morphological controlled highly crystalline particles have been synthesized. Further, the role of Aliquat 336 has been established and a plausible synthetic mechanism has been proposed.

  6. The influence of Glyceria maxima and nitrate input on the composition and nitrate metabolism of the dissimilatory nitrate-reducing bacterial community

    NARCIS (Netherlands)

    Nijburg, J.W.; Laanbroek, H.J.

    1997-01-01

    The influence of nitrate addition and the presence of Glyceria maxima (reed sweetgrass) on the composition and nitrate metabolism of the dissimilatory nitrate-reducing bacterial community was investigated. Anoxic freshwater sediment was incubated in pots with or without G. maxima and with or without

  7. Proton Pump Inhibitor Use and the Antifracture Efficacy of Alendronate

    DEFF Research Database (Denmark)

    Abrahamsen, Bo; Eiken, Pia Agnete; Eastell, Richard

    2011-01-01

    Background: Proton pump inhibitors (PPIs) are widely used in elderly patients and are frequently coadministered in users of oral bisphosphonates. Biologically, PPIs could affect the absorption of calcium, vitamin B12, and bisphosphonates and could affect the osteoclast proton pump, thus interacting...

  8. Effects of pre-harvest foliar application of different rates and sources of calcium on yield and quality of ‘Illona’ cut rose flower

    Directory of Open Access Journals (Sweden)

    K. Mirza Shahi

    2011-12-01

    Full Text Available Short vase life and low quality of cut rose flowers are the main problems of most rose greenhouses in Iran. Calcium is one of the most important nutrients that plays a major role in vase life of cut rose flowers. In this study, a factorial experiment was conducted based on completely randomized blocks design to elucidate the effects of foliar application of calcium rates and sources on yield and quality of rose flowers cv. Illona. Rose plants were sprayed by three rates of 0, 0.3 and 0.6 g/L calcium in combination with two sources of calcium nitrate (Ca(NO32.4H2O and calcium chelate (Ca-EDTA before the harvest. The experiment was conducted in 3 replications during 2005-2007 in Safi Abad Agricultural Research Center, Dezful. The results revealed that rose yield and flower quality indices at harvest time consisting of flowering stem fresh weight and length and length and diameter of buds were not affected by different rates and sources of calcium. But, vase life of cut rose flowers was increased significantly by 2.7 and 2.9 days in 0.3 and 0.6 g/L treatments, respectively (P<0.01. This was due to increased Ca concentration in the rose leaves and petals. There was no significant difference between the calcium nitrate and calcium chelate in supplying calcium and increasing vase life of cut rose flowers. According to the results of the present study, pre-harvest foliar application of calcium nitrate or calcium chelate at the rate of 0.3 g/L is recommended to improve vase life of cut rose flowers in north Khuzestan under greenhouse conditions.

  9. Calcium, vitamin D and bone

    OpenAIRE

    Borg, Andrew A.

    2012-01-01

    Calcium, protein and vitamin D are the main nutrients relevant to bone health. This short article discusses the importance of vitamin D and its relation to calcium homeostasis. The various causes, clinical manifestations and treatment are outlined.

  10. Ammonium and nitrate tolerance in lichens.

    Science.gov (United States)

    Hauck, Markus

    2010-05-01

    Since lichens lack roots and take up water, solutes and gases over the entire thallus surface, these organisms respond more sensitively to changes in atmospheric purity than vascular plants. After centuries where effects of sulphur dioxide and acidity were in the focus of research on atmospheric chemistry and lichens, recently the globally increased levels of ammonia and nitrate increasingly affect lichen vegetation and gave rise to intense research on the tolerance of lichens to nitrogen pollution. The present paper discusses the main findings on the uptake of ammonia and nitrate in the lichen symbiosis and to the tolerance of lichens to eutrophication. Ammonia and nitrate are both efficiently taken up under ambient conditions. The tolerance to high nitrogen levels depends, among others, on the capability of the photobiont to provide sufficient amounts of carbon skeletons for ammonia assimilation. Lowly productive lichens are apparently predisposed to be sensitive to excess nitrogen.

  11. Ryanodine Receptors Selectively Interact with L Type Calcium Channels in Mouse Taste Cells.

    Directory of Open Access Journals (Sweden)

    Michelle R Rebello

    Full Text Available WE REPORTED THAT RYANODINE RECEPTORS ARE EXPRESSED IN TWO DIFFERENT TYPES OF MAMMALIAN PERIPHERAL TASTE RECEPTOR CELLS: Type II and Type III cells. Type II cells lack voltage-gated calcium channels (VGCCs and chemical synapses. In these cells, ryanodine receptors contribute to the taste-evoked calcium signals that are initiated by opening inositol trisphosphate receptors located on internal calcium stores. In Type III cells that do have VGCCs and chemical synapses, ryanodine receptors contribute to the depolarization-dependent calcium influx.The goal of this study was to establish if there was selectivity in the type of VGCC that is associated with the ryanodine receptor in the Type III taste cells or if the ryanodine receptor opens irrespective of the calcium channels involved. We also wished to determine if the ryanodine receptors and VGCCs require a physical linkage to interact or are simply functionally associated with each other. Using calcium imaging and pharmacological inhibitors, we found that ryanodine receptors are selectively associated with L type VGCCs but likely not through a physical linkage.Taste cells are able to undergo calcium induced calcium release through ryanodine receptors to increase the initial calcium influx signal and provide a larger calcium response than would otherwise occur when L type channels are activated in Type III taste cells.

  12. Exposure to extremely low frequency electromagnetic fields alters the calcium dynamics of cultured entorhinal cortex neurons.

    Science.gov (United States)

    Luo, Fen-Lan; Yang, Nian; He, Chao; Li, Hong-Li; Li, Chao; Chen, Fang; Xiong, Jia-Xiang; Hu, Zhi-An; Zhang, Jun

    2014-11-01

    Previous studies have revealed that extremely low frequency electromagnetic field (ELF-EMF) exposure affects neuronal dendritic spine density and NMDAR and AMPAR subunit expressions in the entorhinal cortex (EC). Although calcium signaling has a critical role in control of EC neuronal functions, however, it is still unclear whether the ELF-EMF exposure affects the EC neuronal calcium homeostasis. In the present study, using whole-cell recording and calcium imaging, we record the whole-cell inward currents that contain the voltage-gated calcium currents and show that ELF-EMF (50Hz, 1mT or 3mT, lasting 24h) exposure does not influence these currents. Next, we specifically isolate the high-voltage activated (HVA) and low-voltage activated (LVA) calcium channels-induced currents. Similarly, the activation and inactivation characteristics of these membrane calcium channels are also not influenced by ELF-EMF. Importantly, ELF-EMF exposure reduces the maximum amplitude of the high-K(+)-evoked calcium elevation in EC neurons, which is abolished by thapsigargin, a Ca(2+) ATPase inhibitor, to empty the intracellular calcium stores of EC neurons. Together, these findings indicate that ELF-EMF exposure specifically influences the intracellular calcium dynamics of cultural EC neurons via a calcium channel-independent mechanism.

  13. Calcium ion channel and epilepsy

    Institute of Scientific and Technical Information of China (English)

    Yudan Lü; Weihong Lin; Dihui Ma

    2006-01-01

    OBJECTIVE: To review the relationship between calcium ion channel and epilepsy for well investigating the pathogenesis of epilepsy and probing into the new therapeutic pathway of epilepsy.DATA SOURCES: A computer-based online research Calcium ion channel and epilepsy related articles published between January 1994 and December 2006 in the CKNI and Wanfang database with the key words of "calcium influxion, epilepsy, calcium-channel blocker". The language was limited to Chinese. At the same time,related articles published between January 1993 and December 2006 in Pubmed were searched for on online with the key words of "calcium influxion, epilepsy" in English.STUDY SELECTION: The materials were selected firstly. Inclusive criteria: ① Studies related to calcium ion channel and the pat1hogenesis of epilepsy. ② Studies on the application of calcium ion channel blocker in the treatment of epilepsy. Exclusive criteria: repetitive or irrelated studies.DATA EXTRACTION: According to the criteria, 123 articles were retrieved and 93 were excluded due to repetitive or irrelated studies. Altogether 30 articles met the inclusive criteria, 11 of them were about the structure and characters of calcium ion channel, 10 about calcium ion channel and the pathogenesis of epilepsy and 9 about calcium blocker and the treatment of epilepsy.DATA SYNTHESIS: Calcium ion channels mainly consist of voltage dependent calcium channel and receptor operated calcium channel. Depolarization caused by voltage gating channel-induced influxion is the pathological basis of epileptic attack, and it is found in many studies that many anti-epileptic drugs have potential and direct effect to rivalizing voltage-dependent calcium ion channel.CONCLUSION: Calcium influxion plays an important role in the seizure of epilepsy. Some calcium antagonists seen commonly are being tried in the clinical therapy of epilepsy that is being explored, not applied in clinical practice. If there are enough evidences to

  14. Activation of L-type calcium channels is required for gap junction-mediated intercellular calcium signaling in osteoblastic cells

    Science.gov (United States)

    Jorgensen, Niklas Rye; Teilmann, Stefan Cuoni; Henriksen, Zanne; Civitelli, Roberto; Sorensen, Ole Helmer; Steinberg, Thomas H.

    2003-01-01

    The propagation of mechanically induced intercellular calcium waves (ICW) among osteoblastic cells occurs both by activation of P2Y (purinergic) receptors by extracellular nucleotides, resulting in "fast" ICW, and by gap junctional communication in cells that express connexin43 (Cx43), resulting in "slow" ICW. Human osteoblastic cells transmit intercellular calcium signals by both of these mechanisms. In the current studies we have examined the mechanism of slow gap junction-dependent ICW in osteoblastic cells. In ROS rat osteoblastic cells, gap junction-dependent ICW were inhibited by removal of extracellular calcium, plasma membrane depolarization by high extracellular potassium, and the L-type voltage-operated calcium channel inhibitor, nifedipine. In contrast, all these treatments enhanced the spread of P2 receptor-mediated ICW in UMR rat osteoblastic cells. Using UMR cells transfected to express Cx43 (UMR/Cx43) we confirmed that nifedipine sensitivity of ICW required Cx43 expression. In human osteoblastic cells, gap junction-dependent ICW also required activation of L-type calcium channels and influx of extracellular calcium.

  15. Plasma nitrate and nitrite are increased by a high-nitrate supplement but not by high-nitrate foods in older adults.

    Science.gov (United States)

    Miller, Gary D; Marsh, Anthony P; Dove, Robin W; Beavers, Daniel; Presley, Tennille; Helms, Christine; Bechtold, Erika; King, S Bruce; Kim-Shapiro, Daniel

    2012-03-01

    Little is known about the effect of dietary nitrate on the nitrate/nitrite/nitric oxide cycle in older adults. We examined the effect of a 3-day control diet vs high-nitrate diet, with and without a high-nitrate supplement (beetroot juice), on plasma nitrate and nitrite kinetics and blood pressure using a randomized 4-period crossover controlled design. We hypothesized that the high-nitrate diet would show higher levels of plasma nitrate/nitrite and lower blood pressure compared with the control diet, which would be potentiated by the supplement. Participants were 8 normotensive older men and women (5 female, 3 male, 72.5 ± 4.7 years old) with no overt disease or medications that affect nitric oxide metabolism. Plasma nitrate and nitrite levels and blood pressure were measured before and hourly for 3 hours after each meal. The mean daily changes in plasma nitrate and nitrite were significantly different from baseline for both control diet + supplement (P < .001 and P = .017 for nitrate and nitrite, respectively) and high-nitrate diet + supplement (P = .001 and P = .002), but not for control diet (P = .713 and P = .741) or high-nitrate diet (P = .852 and P = .500). Blood pressure decreased from the morning baseline measure to the three 2-hour postmeal follow-up time points for all treatments, but there was no main effect for treatment. In healthy older adults, a high-nitrate supplement consumed at breakfast elevated plasma nitrate and nitrite levels throughout the day. This observation may have practical utility for the timing of intake of a nitrate supplement with physical activity for older adults with vascular dysfunction.

  16. Calcium carbonate overdose

    Science.gov (United States)

    Calcium carbonate is not very poisonous. Recovery is quite likely. But, long-term overuse is more serious than a single overdose, because it can cause kidney damage. Few people die from an antacid overdose. Keep all medicines in child-proof bottles and out ...

  17. High Blood Calcium (Hypercalcemia)

    Science.gov (United States)

    ... as well as kidney function and levels of calcium in your urine. Your provider may do other tests to further assess your condition, such as checking your blood levels of phosphorus (a mineral). Imaging studies also may be helpful, such as bone ...

  18. Solar Imagery - Chromosphere - Calcium

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset consists of full-disk images of the sun in Calcium (Ca) II K wavelength (393.4 nm). Ca II K imagery reveal magnetic structures of the sun from about 500...

  19. Stochastic Controls on Nitrate Transport and Cycling

    Science.gov (United States)

    Botter, G.; Settin, T.; Alessi Celegon, E.; Marani, M.; Rinaldo, A.

    2005-12-01

    In this paper, the impact of nutrient inputs on basin-scale nitrates losses is investigated in a probabilistic framework by means of a continuous, geomorphologically based, Montecarlo approach, which explicitly tackles the random character of the processes controlling nitrates generation, transformation and transport in river basins. This is obtained by coupling the stochastic generation of climatic and rainfall series with simplified hydrologic and biogeochemical models operating at the hillslope scale. Special attention is devoted to the spatial and temporal variability of nitrogen sources of agricultural origin and to the effect of temporally distributed rainfall fields on the ensuing nitrates leaching. The influence of random climatic variables on bio-geochemical processes affecting the nitrogen cycle in the soil-water system (e.g. plant uptake, nitrification and denitrification, mineralization), is also considered. The approach developed has been applied to a catchment located in North-Eastern Italy and is used to provide probabilistic estimates of the NO_3 load transferred downstream, which is received and accumulated in the Venice lagoon. We found that the nitrogen load introduced by fertilizations significantly affects the pdf of the nitrates content in the soil moisture, leading to prolonged risks of increased nitrates leaching from soil. The model allowed the estimation of the impact of different practices on the probabilistic structure of the basin-scale hydrologic and chemical response. As a result, the return period of the water volumes and of the nitrates loads released into the Venice lagoon has been linked directly to the ongoing climatic, pluviometric and agricultural regimes, with relevant implications for environmental planning activities aimed at achieving sustainable management practices.

  20. Calcium aluminate in alumina

    Science.gov (United States)

    Altay, Arzu

    The properties of ceramic materials are determined not only by the composition and structure of the phases present, but also by the distribution of impurities, intergranular films and second phases. The phase distribution and microstructure both depend on the fabrication techniques, the raw materials used, the phase-equilibrium relations, grain growth and sintering processes. In this dissertation research, various approaches have been employed to understand fundamental phenomena such as grain growth, impurity segregation, second-phase formation and crystallization. The materials system chosen was alumina intentionally doped with calcium. Atomic-scale structural analyses of grain boundaries in alumina were carried on the processed samples. It was found that above certain calcium concentrations, CA6 precipitated as a second phase at all sintering temperatures. The results also showed that abnormal grain growth can occur after precipitation and it is not only related to the calcium level, but it is also temperature dependent. In order to understand the formation mechanism of CA6 precipitates in calcium doped alumina samples, several studies have been carried out using either bulk materials or thin films The crystallization of CA2 and CA6 powders has been studied. Chemical processing techniques were used to synthesize the powders. It was observed that CA2 powders crystallized directly, however CA6 powders crystallized through gamma-Al 2O3 solid solution. The results of energy-loss near-edge spectrometry confirmed that gamma-Al2O3 can dissolve calcium. Calcium aluminate/alumina reaction couples have also been investigated. All reaction couples were heat treated following deposition. It was found that gamma-Al2O3 was formed at the interface as a result of the interfacial reaction between the film and the substrate. gamma-Al 2O3 at the interface was stable at much higher temperatures compared to the bulk gamma-Al2O3 formed prior to the CA6 crystallization. In order to

  1. Calcium addition in straw gasification

    DEFF Research Database (Denmark)

    Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk

    2003-01-01

    The present work focuses on the influence of calcium addition in gasification. The inorganic¿organic element interaction as well as the detailed inorganic¿inorganic elements interaction has been studied. The effect of calcium addition as calcium sugar/molasses solutions to straw significantly...

  2. Techniques for Measurement of Nitrate Movement in Soils

    Science.gov (United States)

    Broadbent, F. E.

    1971-01-01

    Contamination of surface and ground waters with nitrate usually involves leaching through soil of nitrate produced by mineralization of soil organic matter, decomposition of animal wastes or plant residues, or derived from fertilizers. Nitrate concentrations in the soil solution may be measured by several chemical procedures or by the nitrate electrode. since nitrate is produced throughout the soil mass it is difficult to identify a source of nitrate contamination by conventional means. This problem can be solved by use of N-15-enriched or N-15-depleted materials as tracers. The latter is particularly attractive because of the negligible possibility of the tracer hazardous to health.

  3. 9-Amino­acridinium nitrate monohydrate

    OpenAIRE

    Pourayoubi, Mehrdad; Eshtiagh-Hosseini, Hossein; Sanaei Ataabadi, Somayyeh; Mancilla Percino, Teresa; A. Leyva Ramírez, Marco

    2011-01-01

    The pyridine N atom of the cation in the title hydrated salt, C13H11N2 +·NO3 −·H2O, is protonated; the N atom of the NH2 group shows a planar conformation. The former N atom is hydrogen bonded to a water mol­ecule. The amino group is involved in three N—H⋯O hydrogen bonds with two neighboring nitrate anions. The water mol­ecule is hydrogen bonded to two adjacent nitrate anions. In the crystal, this results in a layered network.

  4. 9-Amino­acridinium nitrate monohydrate

    Science.gov (United States)

    Pourayoubi, Mehrdad; Eshtiagh-Hosseini, Hossein; Sanaei Ataabadi, Somayyeh; Mancilla Percino, Teresa; A. Leyva Ramírez, Marco

    2011-01-01

    The pyridine N atom of the cation in the title hydrated salt, C13H11N2 +·NO3 −·H2O, is protonated; the N atom of the NH2 group shows a planar conformation. The former N atom is hydrogen bonded to a water mol­ecule. The amino group is involved in three N—H⋯O hydrogen bonds with two neighboring nitrate anions. The water mol­ecule is hydrogen bonded to two adjacent nitrate anions. In the crystal, this results in a layered network. PMID:21522328

  5. The localization of vanadium- and nitrate-sensitive ATPases in Cucumis sativus L. root cells

    Directory of Open Access Journals (Sweden)

    Grażyna Kłobus

    2014-02-01

    Full Text Available Distinct separation of plasma membrane and tonoplast membranes was attained by centrifugation of cucumber root microsomes in a sucrose density gradient. The fractions enriched in plasma membranes, identified on the basis of the sensitivity of ATPases to VO43- sedimented at a specific density of 1. 1463-1. 1513 g x cm-3. They did not exhibit cytochrome oxidase activity and there was only trace activity of the azide-sensitive ATPase in these fractions. The fractions enriched in tonoplast membranes, having peak activity of nitrate-sensitive ATPase, were found in the region of specific densities of 1. 1082-1.1175. The presence of vanadium-sensitive and azide-sensitive ATPases was not found in these fractions. The ATPase inhibitors, DCCD, DES and EDAC, inhibited the activity of both vanadium-sensitive and nitrate-sensitive ATPases.

  6. Nitrate stimulation of indigenous nitrate-reducing, sulfide-oxidising bacterial community in wastewater anaerobic biofilms.

    Science.gov (United States)

    Garcia-de-Lomas, Juan; Corzo, Alfonso; Carmen Portillo, M; Gonzalez, Juan M; Andrades, Jose A; Saiz-Jimenez, Cesáreo; Garcia-Robledo, Emilio

    2007-07-01

    The role of the nitrate-reducing, sulfide-oxidising bacteria (NR-SOB) in the nitrate-mediated inhibition of sulfide net production by anaerobic wastewater biofilms was analyzed in two experimental bioreactors, continuously fed with the primary effluent of a wastewater treatment plant, one used as control (BRC) and the other one supplemented with nitrate (BRN). This study integrated information from H(2)S and pH microelectrodes, RNA-based molecular techniques, and the time course of biofilm growth and bioreactors water phase. Biofilms were a net source of sulfide for the water phase (2.01 micromol S(2-)(tot)m(-2)s(-1)) in the absence of nitrate dosing. Nitrate addition effectively led to the cessation of sulfide release from biofilms despite which a low rate of net sulfate reduction activity (0.26 micromol S(2-)(tot)m(-2)s(-1)) persisted at a deep layer within the biofilm. Indigenous NR-SOB including Thiomicrospira denitrificans, Arcobacter sp., and Thiobacillus denitrificans were stimulated by nitrate addition resulting in the elimination of most sulfide from the biofilms. Active sulfate reducing bacteria (SRB) represented comparable fractions of total metabolically active bacteria in the libraries obtained from BRN and BRC. However, we detected changes in the taxonomic composition of the SRB community suggesting its adaptation to a higher level of NR-SOB activity in the presence of nitrate.

  7. Excess nitrate loads to coastal waters reduces nitrate removal efficiency: mechanism and implications for coastal eutrophication.

    Science.gov (United States)

    Lunau, Mirko; Voss, Maren; Erickson, Matthew; Dziallas, Claudia; Casciotti, Karen; Ducklow, Hugh

    2013-05-01

    Terrestrial ecosystems are becoming increasingly nitrogen-saturated due to anthropogenic activities, such as agricultural loading with artificial fertilizer. Thus, more and more reactive nitrogen is entering streams and rivers, primarily as nitrate, where it is eventually transported towards the coastal zone. The assimilation of nitrate by coastal phytoplankton and its conversion into organic matter is an important feature of the aquatic nitrogen cycle. Dissolved reactive nitrogen is converted into a particulate form, which eventually undergoes nitrogen removal via microbial denitrification. High and unbalanced nitrate loads to the coastal zone may alter planktonic nitrate assimilation efficiency, due to the narrow stochiometric requirements for nutrients typically shown by these organisms. This implies a cascade of changes for the cycling of other elements, such as carbon, with unknown consequences at the ecosystem level. Here, we report that the nitrate removal efficiency (NRE) of a natural phytoplankton community decreased under high, unbalanced nitrate loads, due to the enhanced recycling of organic nitrogen and subsequent production and microbial transformation of excess ammonium. NRE was inversely correlated with the amount of nitrate present, and mechanistically controlled by dissolved organic nitrogen (DON), and organic carbon (Corg) availability. These findings have important implications for the management of nutrient runoff to coastal zones.

  8. Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

    Science.gov (United States)

    Hiatt-Gipson, Glyn D; Mills, Graham P; Reeves, Claire E

    2016-01-01

    Summary Here we report the chemoselective synthesis of several important, climate relevant isoprene nitrates using silver nitrate to mediate a ’halide for nitrate’ substitution. Employing readily available starting materials, reagents and Horner–Wadsworth–Emmons chemistry the synthesis of easily separable, synthetically versatile ‘key building blocks’ (E)- and (Z)-3-methyl-4-chlorobut-2-en-1-ol as well as (E)- and (Z)-1-((2-methyl-4-bromobut-2-enyloxy)methyl)-4-methoxybenzene has been achieved using cheap, ’off the shelf’ materials. Exploiting their reactivity we have studied their ability to undergo an ‘allylic halide for allylic nitrate’ substitution reaction which we demonstrate generates (E)- and (Z)-3-methyl-4-hydroxybut-2-enyl nitrate, and (E)- and (Z)-2-methyl-4-hydroxybut-2-enyl nitrates (‘isoprene nitrates’) in 66–80% overall yields. Using NOESY experiments the elucidation of the carbon–carbon double bond configuration within the purified isoprene nitrates has been established. Further exemplifying our ‘halide for nitrate’ substitution chemistry we outline the straightforward transformation of (1R,2S)-(−)-myrtenol bromide into the previously unknown monoterpene nitrate (1R,2S)-(−)-myrtenol nitrate. PMID:27340495

  9. Bioceramics of calcium orthophosphates.

    Science.gov (United States)

    Dorozhkin, Sergey V

    2010-03-01

    A strong interest in use of ceramics for biomedical applications appeared in the late 1960's. Used initially as alternatives to metals in order to increase a biocompatibility of implants, bioceramics have become a diverse class of biomaterials, presently including three basic types: relatively bioinert ceramics, bioactive (or surface reactive) and bioresorbable ones. Furthermore, any type of bioceramics could be porous to provide tissue ingrowth. This review is devoted to bioceramics prepared from calcium orthophosphates, which belong to the categories of bioresorbable and bioactive compounds. During the past 30-40 years, there have been a number of major advances in this field. Namely, after the initial work on development of bioceramics that was tolerated in the physiological environment, emphasis was shifted towards the use of bioceramics that interacted with bones by forming a direct chemical bond. By the structural and compositional control, it became possible to choose whether the bioceramics of calcium orthophosphates was biologically stable once incorporated within the skeletal structure or whether it was resorbed over time. At the turn of the millennium, a new concept of calcium orthophosphate bioceramics, which is able to regenerate bone tissues, has been developed. Current biomedical applications of calcium orthophosphate bioceramics include replacements for hips, knees, teeth, tendons and ligaments, as well as repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jawbone, spinal fusion and bone fillers after tumor surgery. Potential future applications of calcium orthophosphate bioceramics will include drug-delivery systems, as well as they will become effective carriers of growth factors, bioactive peptides and/or various types of cells for tissue engineering purposes.

  10. N-type calcium channel blockers: novel therapeutics for the treatment of pain.

    Science.gov (United States)

    Schroeder, C I; Doering, C J; Zamponi, G W; Lewis, R J

    2006-09-01

    Highly selective Ca(v)2.2 voltage-gated calcium channel (VGCC) inhibitors have emerged as a new class of therapeutics for the treatment of chronic and neuropathic pain. Cone snail venoms provided the first drug in class with FDA approval granted in 2005 to Prialt (omega-conotoxin MVIIA, Elan) for the treatment of neuropathic pain. Since this pioneering work, major efforts underway to develop alternative small molecule inhibitors of Ca(v)2.2 calcium channel have met with varied success. This review focuses on the properties of the Ca(v)2.2 calcium channel in different pain states, the action of omega-conotoxins GVIA, MVIIA and CVID, describing their structure-activity relationships and potential as leads for the design of improved Ca(v)2.2 calcium channel therapeutics, and finally the development of small molecules for the treatment of chronic pain.

  11. Nitrate Promotes Capsaicin Accumulation in Capsicum chinense Immobilized Placentas

    Directory of Open Access Journals (Sweden)

    Jeanny G. Aldana-Iuit

    2015-01-01

    Full Text Available In chili pepper’s pods, placental tissue is responsible for the synthesis of capsaicinoids (CAPs, the compounds behind their typical hot flavor or pungency, which are synthesized from phenylalanine and branched amino acids. Placental tissue sections from Habanero peppers (Capsicum chinense Jacq. were immobilized in a calcium alginate matrix and cultured in vitro, either continuously for 28 days or during two 14-day subculture periods. Immobilized placental tissue remained viable and metabolically active for up to 21 days, indicating its ability to interact with media components. CAPs contents abruptly decreased during the first 7 days in culture, probably due to structural damage to the placenta as revealed by scanning electron microcopy. CAPs levels remained low throughout the entire culture period, even though a slight recovery was noted in subcultured placentas. However, doubling the medium’s nitrate content (from 40 to 80 mM resulted in an important increment, reaching values similar to those of intact pod’s placentas. These data suggest that isolated pepper placentas cultured in vitro remain metabolically active and are capable of metabolizing inorganic nitrogen sources, first into amino acids and, then, channeling them to CAP synthesis.

  12. The Acid Catalyzed Nitration of Methanol: Formation of Methyl Nitrate via Aerosol Chemistry

    Science.gov (United States)

    Riffel, Brent G.; Michelsen, Rebecca R.; Iraci, Laura T.

    2004-01-01

    The liquid phase acid catalyzed reaction of methanol with nitric acid to yield methyl nitrate under atmospheric conditions has been investigated using gas phase infrared spectroscopy. This nitration reaction is expected to occur in acidic aerosol particles found in the upper troposphere/lower stratosphere as highly soluble methanol and nitric acid diffuse into these aerosols. Gaseous methyl nitrate is released upon formation, suggesting that some fraction of NO(x) may he liberated from nitric acid (methyl nitrate is later photolyzed to NO(x)) before it is removed from the atmosphere by wet deposition. Thus, this reaction may have important implications for the NO(x) budget. Reactions have been initiated in 45-62 wt% H2SO4 solutions at 10.0 C. Methyl nitrate production rates increased exponentially with acidity within the acidity regime studied. Preliminary calculations suggest that the nitronium ion (NO2(+) is the active nitrating agent under these conditions. The reaction order in methanol appears to depend on the water/methanol ratio and varies from first to zeroth order under conditions investigated. The nitration is first order in nitronium at all acidities investigated. A second order rate constant, kappa(sub 2), has been calculated to be 1 x 10(exp 8)/ M s when the reaction is first order in methanol. Calculations suggest the nitration is first order in methanol under tropospheric conditions. The infinitesimal percentage of nitric acid in the nitronium ion form in this acidity regime probably makes this reaction insignificant for the upper troposphere; however, this nitration may become significant in the mid stratosphere where colder temperatures increase nitric acid solubility and higher sulfuric acid content shifts nitric acid speciation toward the nitronium ion.

  13. Natural nitration of CXCL12 reduces its signaling capacity and chemotactic activity in vitro and abrogates intra-articular lymphocyte recruitment in vivo

    DEFF Research Database (Denmark)

    Janssens, Rik; Mortier, Anneleen; Boff, Daiane

    2016-01-01

    protein-coupled chemokine receptor CXCR4 and the atypical chemokine receptor ACKR3 were comparable. However, [3-NT7]CXCL12 showed a reduced ability to enhance intracellular calcium concentrations, to generate inositol triphosphate, to phosphorylate ERK1/2 and to induce monocyte and lymphocyte chemotaxis...... in vitro. Moreover, nitrated CXCL12 failed to induce in vivo extravasation of lymphocytes to the joint. In summary, nitration on Tyr7 under inflammatory conditions is a novel natural posttranslational regulatory mechanism of CXCL12 which may downregulate the CXCR4-mediated inflammatory and tumor...

  14. Screening of protein kinase inhibitors identifies PKC inhibitors as inhibitors of osteoclastic acid secretion and bone resorption

    Directory of Open Access Journals (Sweden)

    Boutin Jean A

    2010-10-01

    Full Text Available Abstract Background Bone resorption is initiated by osteoclastic acidification of the resorption lacunae. This process is mediated by secretion of protons through the V-ATPase and chloride through the chloride antiporter ClC-7. To shed light on the intracellular signalling controlling extracellular acidification, we screened a protein kinase inhibitor library in human osteoclasts. Methods Human osteoclasts were generated from CD14+ monocytes. The effect of different kinase inhibitors on lysosomal acidification in human osteoclasts was investigated using acridine orange for different incubation times (45 minutes, 4 and 24 hours. The inhibitors were tested in an acid influx assay using microsomes isolated from human osteoclasts. Bone resorption by human osteoclasts on bone slices was measured by calcium release. Cell viability was measured using AlamarBlue. Results Of the 51 compounds investigated only few inhibitors were positive in both acidification and resorption assays. Rottlerin, GF109203X, Hypericin and Ro31-8220 inhibited acid influx in microsomes and bone resorption, while Sphingosine and Palmitoyl-DL-carnitine-Cl showed low levels of inhibition. Rottlerin inhibited lysosomal acidification in human osteoclasts potently. Conclusions In conclusion, a group of inhibitors all indicated to inhibit PKC reduced acidification in human osteoclasts, and thereby bone resorption, indicating that acid secretion by osteoclasts may be specifically regulated by PKC in osteoclasts.

  15. Calcium signaling in taste cells.

    Science.gov (United States)

    Medler, Kathryn F

    2015-09-01

    The sense of taste is a common ability shared by all organisms and is used to detect nutrients as well as potentially harmful compounds. Thus taste is critical to survival. Despite its importance, surprisingly little is known about the mechanisms generating and regulating responses to taste stimuli. All taste responses depend on calcium signals to generate appropriate responses which are relayed to the brain. Some taste cells have conventional synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release to formulate an output signal through a hemichannel. Beyond establishing these characteristics, few studies have focused on understanding how these calcium signals are formed. We identified multiple calcium clearance mechanisms that regulate calcium levels in taste cells as well as a calcium influx that contributes to maintaining appropriate calcium homeostasis in these cells. Multiple factors regulate the evoked taste signals with varying roles in different cell populations. Clearly, calcium signaling is a dynamic process in taste cells and is more complex than has previously been appreciated. This article is part of a Special Issue entitled: 13th European Symposium on Calcium.

  16. The Path to Nitrate Salt Disposition

    Energy Technology Data Exchange (ETDEWEB)

    Funk, David John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-16

    The topic is presented in a series of slides arranged according to the following outline: LANL nitrate salt incident as thermal runaway (thermally sensitive surrogates, full-scale tests), temperature control for processing, treatment options and down selection, assessment of engineering options, anticipated control set for treatment, and summary of the overall steps for RNS.

  17. Reinforced Sisal Fiber with Ferric Nitrate Composites

    Directory of Open Access Journals (Sweden)

    Asif Jehan

    2015-06-01

    Full Text Available Ferric oxide synthesized through annealing route. The present research work deals with ferrite composite prepared using chemical reactions. Ferric nitrates and ammonium chloride doped with sisal fiber has been prepared. The structural behavior of aluminum oxide was studied in XRD, SEM, TEM, FTIR & dielectric measurement. This behavior showed ferrite nature of the sample.

  18. Trend Analyses of Nitrate in Danish Groundwater

    DEFF Research Database (Denmark)

    Hansen, B.; Thorling, L.; Dalgaard, Tommy;

    2012-01-01

    This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis of distribut......This presentation assesses the long-term development in the oxic groundwater nitrate concentration and nitrogen (N) loss due to intensive farming in Denmark. Firstly, up to 20-year time-series from the national groundwater monitoring network enable a statistically systematic analysis...... of distribution, trends and trend reversals in the groundwater nitrate concentration. Secondly, knowledge about the N surplus in Danish agriculture since 1950 is used as an indicator of the potential loss of N. Thirdly, groundwater recharge CFC (Chlorofluorocarbon) age determination allows linking of the first...... two dataset. The development in the nitrate concentration of oxic groundwater clearly mirrors the development in the national agricultural N surplus, and a corresponding trend reversal is found in groundwater. Regulation and technical improvements in the intensive farming in Denmark have succeeded...

  19. Denitration of High Nitrate Salts Using Reductants

    Energy Technology Data Exchange (ETDEWEB)

    HD Smith; EO Jones; AJ Schmidt; AH Zacher; MD Brown; MR Elmore; SR Gano

    1999-05-03

    This report describes work conducted by Pacific Northwest National Laboratory (PNNL), in conjunction with Idaho National Engineering and Environmental Laboratory (INEEL), to remove nitrates in simulated low-activity waste (LAW). The major objective of this work was to provide data for identifying and demonstrating a technically viable and cost-effective approach to condition LAW for immobilization (grout).

  20. Assimilatory Nitrate Reduction in Hansenula polymorpha

    Science.gov (United States)

    Rossi, Beatrice; Berardi, Enrico

    In the last decade, the yeast Hansenula polymorpha (syn.: Pichia angusta) has become an excellent experimental model for genetic and molecular investigations of nitrate assimilation, a subject traditionally investigated in plants, filamentous fungi and bacteria. Among other advantages, H. polymorpha offers classical and molecular genetic tools, as well as the availability of genomic sequence data.

  1. Detonation characteristics of ammonium nitrate products

    NARCIS (Netherlands)

    Kersten, R.J.A.; Hengel, E.I.V. van den; Steen, A.C. van der

    2006-01-01

    The detonation properties of ammonium nitrate (AN) products depend on many factors and are therefore, despite the large amount of information on this topic, difficult to assess. In order to further improve the understanding of the safety properties of AN, the European Fertilizer Manufacturers Associ

  2. Nitrate Salt Surrogate Blending Scoping Test Plan

    Energy Technology Data Exchange (ETDEWEB)

    Anast, Kurt Roy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-13

    Test blending equipment identified in the “Engineering Options Assessment Report: Nitrate Salt Waste Stream Processing”. Determine if the equipment will provide adequate mixing of zeolite and surrogate salt/Swheat stream; optimize equipment type and operational sequencing; impact of baffles and inserts on mixing performance; and means of validating mixing performance

  3. Enzyme catalytic nitration of aromatic compounds.

    Science.gov (United States)

    Kong, Mingming; Wang, Kun; Dong, Runan; Gao, Haijun

    2015-06-01

    Nitroaromatic compounds are important intermediates in organic synthesis. The classic method used to synthesize them is chemical nitration, which involves the use of nitric acid diluted in water or acetic acid, both harmful to the environment. With the development of green chemistry, environmental friendly enzyme catalysis is increasingly employed in chemical processes. In this work, we adopted a non-aqueous horseradish peroxidase (HRP)/NaNO2/H2O2 reaction system to study the structural characteristics of aromatic compounds potentially nitrated by enzyme catalysis, as well as the relationship between the charges on carbon atoms in benzene ring and the nitro product distribution. Investigation of various reaction parameters showed that mild reaction conditions (ambient temperature and neutral pH), plus appropriate use of H2O2 and NaNO2 could prevent inactivation of HRP and polymerization of the substrates. Compared to aqueous-organic co-solvent reaction media, the aqueous-organic two-liquid phase system had great advantages in increasing the dissolved concentration of substrate and alleviating substrate inhibition. Analysis of the aromatic compounds' structural characteristics indicated that substrates containing substituents of NH2 or OH were readily catalyzed. Furthermore, analysis of the relationship between natural bond orbital (NBO) charges on carbon atoms in benzene ring, as calculated by the density functional method, and the nitro product distribution characteristics, demonstrated that the favored nitration sites were the ortho and para positions of substituents in benzene ring, similar to the selectivity of chemical nitration.

  4. A toxicological study of gadolinium nitrate

    Energy Technology Data Exchange (ETDEWEB)

    London, J.E.

    1988-05-01

    The sensitization study in the guinea pig did not show gadolinium nitrate to have potential sensitizing properties. Skin application studies in the rabbit demonstrated that it was cutaneously a severe irritant. This material was considered an irritant in the rabbit eye application studies. 3 refs., 1 tab.

  5. Interaction of lead and calcium uptake by the woodlouse, Porcellio scaber (Isopoda, porcellionidae)

    Energy Technology Data Exchange (ETDEWEB)

    Beeby, A.

    1978-01-01

    Lead and calcium nitrate in a potato base were fed to Porcellio scaber; three levels of each cation were used in a 3/sup 2/ factorial design experiment. The amounts accumulated were determined by atomic absorption spectrophotometric analysis of nitric acid digests of whole animals. Both cations increased markedly in the woodlice with increasng dosage and a clear correlation was found between the rates of uptake of the two.

  6. Water-Soluble Cellulose Derivatives Are Sustainable Additives for Biomimetic Calcium Phosphate Mineralization

    OpenAIRE

    2016-01-01

    The effect of cellulose-based polyelectrolytes on biomimetic calcium phosphate mineralization is described. Three cellulose derivatives, a polyanion, a polycation, and a polyzwitterion were used as additives. Scanning electron microscopy, X-ray diffraction, IR and Raman spectroscopy show that, depending on the composition of the starting solution, hydroxyapatite or brushite precipitates form. Infrared and Raman spectroscopy also show that significant amounts of nitrate ions are incorporated i...

  7. Calcium carbonate nucleation in an alkaline lake surface water, Pyramid Lake, Nevada, USA

    Science.gov (United States)

    Reddy, Michael M.; Hoch, Anthony

    2012-01-01

    Calcium concentration and calcite supersaturation (Ω) needed for calcium carbonate nucleation and crystal growth in Pyramid Lake (PL) surface water were determined during August of 1997, 2000, and 2001. PL surface water has Ω values of 10-16. Notwithstanding high Ω, calcium carbonate growth did not occur on aragonite single crystals suspended PL surface water for several months. However, calcium solution addition to PL surface-water samples caused reproducible calcium carbonate mineral nucleation and crystal growth. Mean PL surface-water calcium concentration at nucleation was 2.33 mM (n = 10), a value about nine times higher than the ambient PL surface-water calcium concentration (0.26 mM); mean Ω at nucleation (109 with a standard deviation of 8) is about eight times the PL surface-water Ω. Calcium concentration and Ω regulated the calcium carbonate formation in PL nucleation experiments and surface water. Unfiltered samples nucleated at lower Ω than filtered samples. Calcium concentration and Ω at nucleation for experiments in the presence of added particles were within one standard deviation of the mean for all samples. Calcium carbonate formation rates followed a simple rate expression of the form, rate (mM/min) = A (Ω) + B. The best fit rate equation "Rate (Δ mM/Δ min) = -0.0026 Ω + 0.0175 (r = 0.904, n = 10)" was statistically significant at greater than the 0.01 confidence level and gives, after rearrangement, Ω at zero rate of 6.7. Nucleation in PL surface water and morphology of calcium carbonate particles formed in PL nucleation experiments and in PL surface-water samples suggest crystal growth inhibition by multiple substances present in PL surface water mediates PL calcium carbonate formation, but there is insufficient information to determine the chemical nature of all inhibitors.

  8. Proton pump inhibitors and osteoporosis

    DEFF Research Database (Denmark)

    Andersen, Bjarne Nesgaard; Johansen, Per Birger; Abrahamsen, Bo

    2016-01-01

    PURPOSE OF REVIEW: The purpose of the review is to provide an update on recent advances in the evidence based on proton pump inhibitors (PPI) as a possible cause of osteoporosis and osteoporotic fractures. This review focuses, in particular, on new studies published in the last 18 months and a di......PURPOSE OF REVIEW: The purpose of the review is to provide an update on recent advances in the evidence based on proton pump inhibitors (PPI) as a possible cause of osteoporosis and osteoporotic fractures. This review focuses, in particular, on new studies published in the last 18 months...... and a discussion of these findings and how this has influenced our understanding of this association, the clinical impact and the underlying pathophysiology. RECENT FINDINGS: New studies have further strengthened existing evidence linking use of PPIs to osteoporosis. Short-term use does not appear to pose a lower...... risk than long-term use. There is a continued lack of conclusive studies identifying the pathogenesis. Direct effects on calcium absorption or on osteoblast or osteoclast action cannot at present plausibly explain the mechanism. SUMMARY: The use of PPIs is a risk factor for development of osteoporosis...

  9. Fruit Calcium: Transport and Physiology

    Directory of Open Access Journals (Sweden)

    Bradleigh eHocking

    2016-04-01

    Full Text Available Calcium has well-documented roles in plant signaling, water relations and cell wall interactions. Significant research into how calcium impacts these individual processes in various tissues has been carried out; however, the influence of calcium on fruit ripening has not been thoroughly explored. Here, we review the current state of knowledge on how calcium may impact fruit development, physical traits and disease susceptibility through facilitating developmental and stress response signaling, stabilizing membranes, influencing water relations and modifying cell wall properties through cross-linking of de-esterified pectins. We explore the involvement of calcium in hormone signaling integral to ripening and the physiological mechanisms behind common disorders that have been associated with fruit calcium deficiency (e.g. blossom end rot in tomatoes or bitter pit in apples. This review works towards an improved understanding of how the many roles of calcium interact to influence fruit ripening, and proposes future research directions to fill knowledge gaps. Specifically, we focus mostly on grapes and present a model that integrates existing knowledge around these various functions of calcium in fruit, which provides a basis for understanding the physiological impacts of sub-optimal calcium nutrition in grapes. Calcium accumulation and distribution in fruit is shown to be highly dependent on water delivery and cell wall interactions in the apoplasm. Localized calcium deficiencies observed in particular species or varieties can result from differences in xylem morphology, fruit water relations and pectin composition, and can cause leaky membranes, irregular cell wall softening, impaired hormonal signaling and aberrant fruit development. We propose that the role of apoplasmic calcium-pectin crosslinking, particularly in the xylem, is an understudied area that may have a key influence on fruit water relations. Furthermore, we believe that improved

  10. The determination of calcium in phosphate, carbonate, and silicate rocks by flame photometer

    Science.gov (United States)

    Kramer, Henry

    1956-01-01

    A method has been developed for the determination of calcium in phosphate, carbonate, and silicate rocks using the Beckman flame photometer, with photomultiplier attachement. The sample is dissolved in hydrofluoric, nitric, and perchloric acids, the hydrofluoric and nitric acids are expelled, a radiation buffer consisting of aluminum, magnesium, iron, sodium, potassium, phosphoric acid, and nitric acid is added, and the solution is atomized in an oxy-hydrogen flame with an instrument setting of 554 mµ. Measurements are made by comparison against calcium standards, prepared in the same manner, in the 0 to 50 ppm range. The suppression of calcium emission by aluminum and phosphate was overcome by the addition of a large excess of magnesium. This addition almost completely restores the standard curve obtained from a solution of calcium nitrate. Interference was noted when the iron concentration in the aspirated solution (including the iron from the buffer) exceeded 100 ppm iron. Other common rock-forming elements did not interfere. The results obtained by this procedure are within ± 2 percent of the calcium oxide values obtained by other methods in the range 1 to 95 percent calcium oxide. In the 0 to 1 percent calcium oxide range the method compares favorably with standard methods.

  11. Calcium distribution in the subtropical Atlantic Ocean: Implications for calcium excess and saturation horizons

    Science.gov (United States)

    Rosón, Gabriel; Guallart, Elisa F.; Pérez, Fiz F.; Ríos, Aida F.

    2016-06-01

    This study constituted the first attempt to measure dissolved calcium ([Ca2 +]meas) in the subtropical North Atlantic, during a zonal transoceanic cruise along 24.5°N (WOCE A05 section), in summer 1992. [Ca2 +]meas was obtained in 20 full-depth equidistant stations along the section, showing that their gradients are rather sensitive to horizontal and vertical water mass distribution. Deep waters along 24.5°N systematically show a positive calcium excess of 20 ± 14 μmol·kg- 1, i.e., more [Ca2 +] than expected by CaCO3 dissolution and organic matter oxidation (estimated by total alkalinity and nitrate). CaCO3 settling and benthic dissolution accounts for 70% and the North Atlantic plus Arctic riverine inputs of HCO3- for the remaining 30%. Combining [Ca2 +]meas and CO2 data sets, carbonate mineral saturation states distributions for aragonite and calcite can be obtained. The two solubility ratios resulted, on average, 0.5% smaller than if conservative behavior for Ca2 + was assumed (an approach widely followed when [Ca2 +]meas is unknown). As a result, shallower saturation horizon depths for both carbonate states (19 dbar for aragonite and 10 dbar for calcite) are yielded if [Ca2 +]meas is taken into account instead than estimated from salinity.

  12. Benefits of Safer Drinking Water: The Value of Nitrate Reduction

    OpenAIRE

    Crutchfield, Stephen R.; Cooper, Joseph C.; Hellerstein, Daniel

    1997-01-01

    Nitrates in drinking water, which may come from nitrogen fertilizers applied to crops, are a potential health risk. This report evaluates the potential benefits of reducing human exposure to nitrates in the drinking water supply. In a survey, respondents were asked a series of questions about their willingness to pay for a hypothetical water filter, which would reduce their risk of nitrate exposure. If nitrates in the respondent's drinking water were to exceed the EPA minimum safety standard,...

  13. DISTILLATION OF CALCIUM

    Science.gov (United States)

    Barton, J.

    1954-07-27

    This invention relates to an improvement in the process for the purification of caicium or magnesium containing an alkali metal as impurity, which comprises distiiling a batch of the mixture in two stages, the first stage distillation being carried out in the presence of an inert gas at an absolute pressure substantially greater than the vapor pressure of calcium or maguesium at the temperature of distillation, but less than the vaper pressure at that temperature of the alkali metal impurity so that only the alkali metal is vaporized and condensed on a condensing surface. A second stage distilso that substantially only the calcium or magnesium distills under its own vapor pressure only and condenses in solid form on a lower condensing surface.

  14. Synthesis of calcium superoxide

    Science.gov (United States)

    Rewick, R. T.; Blucher, W. G.; Estacio, P. L.

    1972-01-01

    Efforts to prepare Ca(O2) sub 2 from reactions of calcium compounds with 100% O3 and with O(D-1) atoms generated by photolysis of O3 at 2537 A are described. Samples of Ca(OH) sub 2, CaO, CaO2, Ca metal, and mixtures containing suspected impurities to promote reaction have been treated with excess O3 under static and flow conditions in the presence and absence of UV irradiation. Studies with KO2 suggest that the superoxide anion is stable to radiation at 2537 A but reacts with oxygen atoms generated by the photolysis of O3 to form KO3. Calcium superoxide is expected to behave in an analogous.

  15. Isolation and preliminary characterization of a respiratory nitrate reductase from hydrocarbon-degrading bacterium Gordonia alkanivorans S7.

    Science.gov (United States)

    Romanowska, Irena; Kwapisz, Ewa; Mitka, Magdalena; Bielecki, Stanisław

    2010-06-01

    Gordonia alkanivorans S7 is an efficient degrader of fuel oil hydrocarbons that can simultaneously utilize oxygen and nitrate as electron acceptors. The respiratory nitrate reductase (Nar) from this organism has been isolated using ion exchange chromatography and gel filtration, and then preliminarily characterized. PAGE, SDS-PAGE and gel filtration chromatography revealed that Nar consisted of three subunits of 103, 53 and 25 kDa. The enzyme was optimally active at pH 7.9 and 40 degrees C. K(m) values for NO(3)(-) (110 microM) and for ClO(3)(-) (138 microM) were determined for a reduced viologen as an electron donor. The purified Nar did not use NADH as the electron donor to reduce nitrate or chlorate. Azide was a strong inhibitor of its activity. Our results imply that enzyme isolated from G. alkanivorans S7 is a respiratory membrane-bound nitrate reductase. This is the first report of purification of a nitrate reductase from Gordonia species.

  16. Models of calcium signalling

    CERN Document Server

    Dupont, Geneviève; Kirk, Vivien; Sneyd, James

    2016-01-01

    This book discusses the ways in which mathematical, computational, and modelling methods can be used to help understand the dynamics of intracellular calcium. The concentration of free intracellular calcium is vital for controlling a wide range of cellular processes, and is thus of great physiological importance. However, because of the complex ways in which the calcium concentration varies, it is also of great mathematical interest.This book presents the general modelling theory as well as a large number of specific case examples, to show how mathematical modelling can interact with experimental approaches, in an interdisciplinary and multifaceted approach to the study of an important physiological control mechanism. Geneviève Dupont is FNRS Research Director at the Unit of Theoretical Chronobiology of the Université Libre de Bruxelles;Martin Falcke is head of the Mathematical Cell Physiology group at the Max Delbrück Center for Molecular Medicine, Berlin;Vivien Kirk is an Associate Professor in the Depar...

  17. Extraction of nitric acid, uranyl nitrate, and bismuth nitrate from aqueous nitric acid solutions with CMPO

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, B.B.

    1995-08-01

    DOE sponsored development of the transuranium extraction (TRUEX) process for removing actinides from radioactive wastes. The solvent is a mixture of CMPO and TBP. Since the extraction characteristics of CMPO are not as well understood as those of TBP, the extraction of nitric acid, uranyl nitrate, and bismuth nitrate with CMPO (dissolved in n-dodecane) were studied. Results indicate that CMPO extracts nitric acid with a 1:1 stoichiometry; equilibrium constant is 2. 660{plus_minus}0.092 at 25 C, and extraction enthalpy is -5. 46{plus_minus}0.46 kcal/mol. Slope analysis indicates that uranyl nitrate extracts with a mixed equilibria of 1:1 and 2:1 stoichiometries in nearly equal proportion. Equil. constant of the 2: 1 extraction was 1.213 {times} 10{sup 6}{plus_minus}3.56 {times} 10{sup 4} at 25 C; reaction enthalpy was -9.610{plus_minus}0.594 kcal/mol. Nitration complexation constant is 8.412{plus_minus}0.579, with an enthalpy of -10.72{plus_minus}1.87 kcal/mol. Bismuth nitrate also extracts with a mixed equilibria of (perhaps) 1:1 and 2:1 stoichiometries. A 2:1 extraction equilibrium and a nitrate complexation adequately model the data. Kinetics and enthalpies were also measured.

  18. Nitrate to ammonia ceramic (NAC) bench scale stabilization study

    Energy Technology Data Exchange (ETDEWEB)

    Caime, W.J.; Hoeffner, S.L. [RUST - Clemson Technical Center, Anderson, SC (United States)

    1995-10-01

    Department of Energy (DOE) sites such as the Hanford site, Idaho National Engineering Laboratory (INEL), Savannah River site, Oak Ridge National Laboratory (ORNL) have large quantities of sodium-nitrate based liquid wastes. A process to reduce the nitrates to ammonia has been developed at ORNL. This technology creates a sludge lower in nitrates. This report describes stabilization possibilities of the sludge.

  19. A nitrate sensitive planar optode; performance and interferences

    DEFF Research Database (Denmark)

    Pedersen, Lasse; Dechesne, Arnaud; Smets, Barth F.

    2015-01-01

    We present a newly developed nitrate sensitive planar optode. It exhibits a linear response to nitrate from 1 to 50 mM at pH 8.0, a fast response time below 10 s and a good lifetime, allowing for fast two dimensional nitrate measurements over long periods of time. Interference from nitrite...

  20. 78 FR 32690 - Certain Ammonium Nitrate From Ukraine

    Science.gov (United States)

    2013-05-31

    ... COMMISSION Certain Ammonium Nitrate From Ukraine Determination On the basis of the record \\1\\ developed in... antidumping duty order on certain ammonium nitrate from Ukraine would be likely to lead to continuation or... Publication 4396 (May 2013), entitled Certain Ammonium Nitrate from Ukraine: Investigation No....

  1. 40 CFR 721.7500 - Nitrate polyether polyol (generic name).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Nitrate polyether polyol (generic name... Substances § 721.7500 Nitrate polyether polyol (generic name). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance nitrate polyether polyol (PMN P88-2540)...

  2. 21 CFR 176.320 - Sodium nitrate-urea complex.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrate-urea complex. 176.320 Section 176... Substances for Use Only as Components of Paper and Paperboard § 176.320 Sodium nitrate-urea complex. Sodium nitrate-urea complex may be safely used as a component of articles intended for use in...

  3. 40 CFR 721.5769 - Mixture of nitrated alkylated phenols.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Mixture of nitrated alkylated phenols... Substances § 721.5769 Mixture of nitrated alkylated phenols. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as a mixture of nitrated alkylated...

  4. Nitrate ammonification in mangrove soils: A hidden source of nitrite?

    NARCIS (Netherlands)

    Balk, Melike; Laverman, A.M.; Keuskamp, Joost A.; Laanbroek, Hendrikus J.

    2015-01-01

    Nitrate reduction is considered to be a minor microbial pathway in the oxidation of mangrove-derived organic matter due to a limited supply of nitrate in mangrove soils. At a limited availability of this electron acceptor compared to the supply of degradable carbon, nitrate ammonification is thought

  5. 76 FR 49449 - Continuation of Antidumping Duty Order on Solid Fertilizer Grade Ammonium Nitrate From the...

    Science.gov (United States)

    2011-08-10

    ... Nitrate From the Russian Federation AGENCY: Import Administration, International Trade Administration... duty investigation on solid fertilizer grade ammonium nitrate (``ammonium nitrate'') from the Russian... and the ITC instituted a second sunset review of the ammonium nitrate suspended investigation....

  6. 76 FR 23569 - Termination of the Suspension Agreement on Solid Fertilizer Grade Ammonium Nitrate From the...

    Science.gov (United States)

    2011-04-27

    ... Nitrate From the Russian Federation and Notice of Antidumping Duty Order AGENCY: Import Administration... (``AD'') Investigation on Solid Fertilizer Grade Ammonium Nitrate from the Russian Federation (``the... determine whether imports of solid fertilizer grade ammonium nitrate (``ammonium nitrate'') from Russia...

  7. Proton pump inhibitors

    Science.gov (United States)

    Proton pump inhibitors (PPIs) are medicines that work by reducing the amount of stomach acid made by ... Proton pump inhibitors are used to: Relieve symptoms of acid reflux, or gastroesophageal reflux disease (GERD). This ...

  8. Calcium signalling and calcium channels: evolution and general principles.

    Science.gov (United States)

    Verkhratsky, Alexei; Parpura, Vladimir

    2014-09-15

    Calcium as a divalent cation was selected early in evolution as a signaling molecule to be used by both prokaryotes and eukaryotes. Its low cytosolic concentration likely reflects the initial concentration of this ion in the primordial soup/ocean as unicellular organisms were formed. As the concentration of calcium in the ocean subsequently increased, so did the diversity of homeostatic molecules handling calcium. This includes the plasma membrane channels that allowed the calcium entry, as well as extrusion mechanisms, i.e., exchangers and pumps. Further diversification occurred with the evolution of intracellular organelles, in particular the endoplasmic reticulum and mitochondria, which also contain channels, exchanger(s) and pumps to handle the homeostasis of calcium ions. Calcium signalling system, based around coordinated interactions of the above molecular entities, can be activated by the opening of voltage-gated channels, neurotransmitters, second messengers and/or mechanical stimulation, and as such is all-pervading pathway in physiology and pathophysiology of organisms.

  9. Elemental calcium intake associated with calcium acetate/calcium carbonate in the treatment of hyperphosphatemia

    Science.gov (United States)

    Wilson, Rosamund J; Copley, J Brian

    2017-01-01

    Background Calcium-based and non-calcium-based phosphate binders have similar efficacy in the treatment of hyperphosphatemia; however, calcium-based binders may be associated with hypercalcemia, vascular calcification, and adynamic bone disease. Scope A post hoc analysis was carried out of data from a 16-week, Phase IV study of patients with end-stage renal disease (ESRD) who switched to lanthanum carbonate monotherapy from baseline calcium acetate/calcium carbonate monotherapy. Of the intent-to-treat population (N=2520), 752 patients with recorded dose data for calcium acetate (n=551)/calcium carbonate (n=201) at baseline and lanthanum carbonate at week 16 were studied. Elemental calcium intake, serum phosphate, corrected serum calcium, and serum intact parathyroid hormone levels were analyzed. Findings Of the 551 patients with calcium acetate dose data, 271 (49.2%) had an elemental calcium intake of at least 1.5 g/day at baseline, and 142 (25.8%) had an intake of at least 2.0 g/day. Mean (95% confidence interval [CI]) serum phosphate levels were 6.1 (5.89, 6.21) mg/dL at baseline and 6.2 (6.04, 6.38) mg/dL at 16 weeks; mean (95% CI) corrected serum calcium levels were 9.3 (9.16, 9.44) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Of the 201 patients with calcium carbonate dose data, 117 (58.2%) had an elemental calcium intake of at least 1.5 g/day, and 76 (37.8%) had an intake of at least 2.0 g/day. Mean (95% CI) serum phosphate levels were 5.8 (5.52, 6.06) mg/dL at baseline and 5.8 (5.53, 6.05) mg/dL at week 16; mean (95% CI) corrected serum calcium levels were 9.7 (9.15, 10.25) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Conclusion Calcium acetate/calcium carbonate phosphate binders, taken to control serum phosphate levels, may result in high levels of elemental calcium intake. This may lead to complications related to calcium balance. PMID:28182142

  10. Effect of Bcl-2 and caspase-3 on calcium distribution in apoptosis of HL-60 cells

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Apoptosis manifests in two major execution programs downstream of the death signal: the caspase pathway and organelle dysfunction. An important antiapoptosis factor, Bcl-2 protein, contributes in caspase pathway of apoptosis. Calcium, an important intracellular signal element in cells, is also observed to have changes during apoptosis, which maybe affected by Bcl2 protein. We have previously reported that in Harringtonine (HT) induced apoptosis of HL-60 cells, there's a change of intracellular calcium distribution, moving from cytoplast especially Golgi's apparatus to nucleus and accumulating there with the highest concentration. We report here that caspase-3 becomes activated in HT-induced apoptosis of HL-60 cells, which can be inhibited by overexpression of Bcl-2 protein. No sign of apoptosis or intracellular calcium movement from Golgi's apparatus to nucleus in HL-60 cells overexpressing Bcl-2 or treated with Ac-DEVD-CHO, a specific inhibitor of caspase-3. The results indicate that activated caspase-3 can promote the movement of intracellular calcium from Golgi's apparatus to nucleus, and the process is inhibited by Ac-DEVD-CHO (inhibitor of caspas-3), and that Bcl-2 can inhibit the movement and accumulation of intracellular calcium in nucleus through its inhibition on caspase3. Calcium relocalization in apoptosis seems to be irreversible, which is different from the intracellular calcium changes caused by growth factor.

  11. Fibroblast growth factor-23 negates 1,25(OH)2D3-induced intestinal calcium transport by reducing the transcellular and paracellular calcium fluxes.

    Science.gov (United States)

    Khuituan, Pissared; Wongdee, Kannikar; Jantarajit, Walailuk; Suntornsaratoon, Panan; Krishnamra, Nateetip; Charoenphandhu, Narattaphol

    2013-08-01

    The calciotropic hormone 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] has been known to stimulate intestinal calcium transport via both transcellular and paracellular pathways. Recently, we reported that the 1,25(OH)2D3-enhanced calcium transport in the mouse duodenum could be abolished by fibroblast growth factor (FGF)-23, but the targeted calcium transport pathway has been elusive. Herein, the 1,25(OH)2D3-enhanced calcium transport was markedly inhibited by FGF-23 and inhibitors of the basolateral calcium transporters, NCX1 and PMCA1b, suggesting the negative effect of FGF-23 on the transcellular calcium transport. Similar results could be observed in the intestinal epithelium-like Caco-2 monolayer. Although the Arrhenius plot indicated that FGF-23 decreased the potential barrier (e.g., activation energy) of the paracellular calcium movement, FGF-23 was found to modestly decrease the 1,25(OH)2D3-enhanced paracellular calcium transport and calcium permeability. Moreover, FGF-23 affected the 1,25(OH)2D3-induced change in duodenal water permeability as determined by tritiated water, but both 1,25(OH)2D3 and FGF-23 were without effects on the transepithelial fluxes of paracellular markers, (3)H-mannitol and (14)C-polyethylene glycol. It could be concluded that FGF-23 diminished the 1,25(OH)2D3-enhanced calcium absorption through the transcellular and paracellular pathways. Our findings have thus corroborated the presence of a bone-kidney-intestinal axis of FGF-23/vitamin D system in the regulation of calcium homeostasis.

  12. Solid state interaction studies on binary nitrate mixtures of uranyl nitrate hexahydrate and lanthanum nitrate hexahydrate at elevated temperatures

    Science.gov (United States)

    Kalekar, Bhupesh; Raje, Naina; Reddy, A. V. R.

    2017-02-01

    Interaction behavior of uranyl nitrate hexahydrate (UNH) and lanthanum nitrate hexahydrate (LaNH) have been investigated on the mixtures in different molar ratios of the two precursors and monitoring the reactions at elevated temperatures with thermoanalytical and X-ray diffraction measurement techniques. During the decomposition of equimolar mixture of LaNH and UNH, formation of lanthanum uranate (U0.5La0.5)O2, was seen by the temperature of 500 °C along with lanthanum oxide (La2O3) and uranium trioxide (UO3). By the temperature of 700 °C, the formation of uranium sesquioxide (U3O8) was observed along with (U0.5La0.5)O2 as end products in uranium rich mixtures. Lanthanum rich compositions decomposed by the temperature of 700 °C to give (U0.5La0.5)O2 and La2O3 as end products.

  13. Green Plant Extract as a passivationpromoting Inhibitor for Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Abdulrahman A. S.

    2011-08-01

    Full Text Available The present corrosion inhibitors in market for the protection of steel reinforcement in concrete exposed to chloride attack are toxic to the environment and compromises sustainability drives. There is the needs to develop inhibitor that are eco-friendly and sustainable. In this work the ability of hydrophobic green plant extracts inhibitor (Bambusa arundinacea to repassivates the chloride induced corrosion of steel was studied. Its efficacy and effectiveness was also compared with calcium nitrite inhibitor. Concrete mix was designed to 30MPa with 0.45 W/C ratios and 1.5% weight of cement content of chloride was added to initiate corrosion.Inhibitors additions were 2%. Electrochemical impedance spectroscopy, linear polarization resistance and Field emission spectroscopy (FESEM were used to monitor corrosion behavior of steel at 180 days exposure period. Corrosion rate of the inhibitors studied showed that Bambusa Arundinacea is superior as compared to calcium nitrite as results of its high concrete resistivity, chloride binding property and polarization resistance. Bambusa Arundinacea may be considered a better substitute for nitrite based corrosion inhibiting admixtures for durable concrete structures due its versatility.

  14. Effect of Sodium Nitrate and Nitrate Reducing Bacteria on In vitro Methane Production and Fermentation with Buffalo Rumen Liquor.

    Science.gov (United States)

    Sakthivel, Pillanatham Civalingam; Kamra, Devki Nandan; Agarwal, Neeta; Chaudhary, Lal Chandra

    2012-06-01

    Nitrate can serve as a terminal electron acceptor in place of carbon dioxide and inhibit methane emission in the rumen and nitrate reducing bacteria might help enhance the reduction of nitrate/nitrite, which depends on the type of feed offered to animals. In this study the effects of three levels of sodium nitrate (0, 5, 10 mM) on fermentation of three diets varying in their wheat straw to concentrate ratio (700:300, low concentrate, LC; 500:500, medium concentrate, MC and 300:700, high concentrate, HC diet) were investigated in vitro using buffalo rumen liquor as inoculum. Nitrate reducing bacteria, isolated from the rumen of buffalo were tested as a probiotic to study if it could help in enhancing methane inhibition in vitro. Inclusion of sodium nitrate at 5 or 10 mM reduced (pfeed reduced (pfeeding and introduced individually (3 ml containing 1.2 to 2.3×10(6) cfu/ml) into in vitro incubations containing the MC diet with 10 mM sodium nitrate. Addition of live culture of NRBB 57 resulted in complete removal of nitrate and nitrite from the medium with a further reduction in methane and no effect on IVTD compared to the control treatments containing nitrate with autoclaved cultures or nitrate without any culture. The data revealed that nitrate reducing bacteria can be used as probiotic to prevent the accumulation of nitrite when sodium nitrate is used to reduce in vitro methane emissions.

  15. Open-Source Photometric System for Enzymatic Nitrate Quantification.

    Science.gov (United States)

    Wittbrodt, B T; Squires, D A; Walbeck, J; Campbell, E; Campbell, W H; Pearce, J M

    2015-01-01

    Nitrate, the most oxidized form of nitrogen, is regulated to protect people and animals from harmful levels as there is a large over abundance due to anthropogenic factors. Widespread field testing for nitrate could begin to address the nitrate pollution problem, however, the Cadmium Reduction Method, the leading certified method to detect and quantify nitrate, demands the use of a toxic heavy metal. An alternative, the recently proposed Environmental Protection Agency Nitrate Reductase Nitrate-Nitrogen Analysis Method, eliminates this problem but requires an expensive proprietary spectrophotometer. The development of an inexpensive portable, handheld photometer will greatly expedite field nitrate analysis to combat pollution. To accomplish this goal, a methodology for the design, development, and technical validation of an improved open-source water testing platform capable of performing Nitrate Reductase Nitrate-Nitrogen Analysis Method. This approach is evaluated for its potential to i) eliminate the need for toxic chemicals in water testing for nitrate and nitrite, ii) reduce the cost of equipment to perform this method for measurement for water quality, and iii) make the method easier to carryout in the field. The device is able to perform as well as commercial proprietary systems for less than 15% of the cost for materials. This allows for greater access to the technology and the new, safer nitrate testing technique.

  16. Nitrate intake from drinking water on Tenerife island (Spain).

    Science.gov (United States)

    Caballero Mesa, J M; Rubio Armendáriz, C; Hardisson de la Torre, A

    2003-01-20

    Although meat and vegetable products contain higher concentrations of nitrate, drinking water is the fastest and most direct form of nitrate consumption by the population. It becomes contaminated with nitrates when sea water infiltrates fresh water aquifers and when rain and irrigation water wash through soils that have been excessively treated with nitrated fertilizers. Nitrates are of great toxicological interest as they are involved in the origin of nitrites and nitrosamines and the development of metahaemoglobinaemia in infants. The objective of this study was to determine the quantities of NO(3)(-) in the water supply of each of the Island's municipalities and in the leading brands of bottled waters consumed by the population of Tenerife. This parameter is necessary for the determination of Acceptable Daily Intake (A.D.I.) of nitrates from drinking water. With one unremarkable exception, the nitrate levels found in the water analyzed were optimum for human consumption and amply complied with current European Legislation.

  17. Nitrate removal by microbial enhancement in a riparian wetland.

    Science.gov (United States)

    Pei, Yuansheng; Yang, Zhifeng; Tian, Binghui

    2010-07-01

    A riparian wetland (RW) was constructed in a river bend to study the effect of the addition of Bacillus subtilis FY99-01 on nitrate removal. Nitrate was removed more efficiently in the summer than in the winter owing to integrated hydraulic, microbial and environmental effects. The maximal nitrate removal and the mean nitrate loss rate in the RW were 36.1% and 50.5 g/m(2)/yr, respectively. Statistic analyses indicated that the redox potential was very significant to denitrification while organic matter in the outflow, temperature and nitrate in the inflow significantly affected nitrate removal. These results suggest that an RW can be a cost-effective approach to enhance microbial nitrate removal and can potentially be extended to similar river bends.

  18. Understanding nitrate assimilation and its regulation in microalgae.

    Science.gov (United States)

    Sanz-Luque, Emanuel; Chamizo-Ampudia, Alejandro; Llamas, Angel; Galvan, Aurora; Fernandez, Emilio

    2015-01-01

    Nitrate assimilation is a key process for nitrogen (N) acquisition in green microalgae. Among Chlorophyte algae, Chlamydomonas reinhardtii has resulted to be a good model system to unravel important facts of this process, and has provided important insights for agriculturally relevant plants. In this work, the recent findings on nitrate transport, nitrate reduction and the regulation of nitrate assimilation are presented in this and several other algae. Latest data have shown nitric oxide (NO) as an important signal molecule in the transcriptional and posttranslational regulation of nitrate reductase and inorganic N transport. Participation of regulatory genes and proteins in positive and negative signaling of the pathway and the mechanisms involved in the regulation of nitrate assimilation, as well as those involved in Molybdenum cofactor synthesis required to nitrate assimilation, are critically reviewed.

  19. Understanding nitrate assimilation and its regulation in microalgae

    Directory of Open Access Journals (Sweden)

    Emanuel eSanz-Luque

    2015-10-01

    Full Text Available Nitrate assimilation is a key process for nitrogen (N acquisition in green microalgae. Among Chlorophyte algae, Chlamydomonas reinhardtii has resulted to be a good model system to unravel important facts of this process, and has provided important insights for agriculturally relevant plants. In this work, the recent findings on nitrate transport, nitrate reduction and the regulation of nitrate assimilation are presented in this and several other algae. Latest data have shown nitric oxide (NO as an important signal molecule in the transcriptional and posttranslational regulation of nitrate reductase and inorganic N transport. Participation of regulatory genes and proteins in positive and negative signaling of the pathway and the mechanisms involved in the regulation of nitrate assimilation, as well as those involved in Molybdenum cofactor synthesis required to nitrate assimilation, are critically reviewed.

  20. Impact of adding nitrate or increasing the lipid content of two contrasting diets on blood methaemoglobin and performance of two breeds of finishing beef steers.

    Science.gov (United States)

    Duthie, C-A; Rooke, J A; Troy, S; Hyslop, J J; Ross, D W; Waterhouse, A; Roehe, R

    2016-05-01

    Adding nitrate to the diet or increasing the concentration of dietary lipid are effective strategies for reducing enteric methane emissions. This study investigated their effect on health and performance of finishing beef cattle. The experiment was a two×two×three factorial design comprising two breeds (CHX, crossbred Charolais; LU, Luing); two basal diets consisting of (g/kg dry matter (DM), forage to concentrate ratios) 520 : 480 (Mixed) or 84 : 916 (Concentrate); and three treatments: (i) control with rapeseed meal as the main protein source replaced with either (ii) calcium nitrate (18 g nitrate/kg diet DM) or (iii) rapeseed cake (RSC, increasing acid hydrolysed ether extract from 25 to 48 g/kg diet DM). Steers (n=84) were allocated to each of the six basal diet×treatments in equal numbers of each breed with feed offered ad libitum. Blood methaemoglobin (MetHb) concentrations (marker for nitrate poisoning) were monitored throughout the study in steers receiving nitrate. After dietary adaptation over 28 days, individual animal intake, performance and feed efficiency were recorded for a test period of 56 days. Blood MetHb concentrations were low and similar up to 14 g nitrate/kg diet DM but increased when nitrate increased to 18 g nitrate/kg diet DM (P0.05). Neither basal diet nor treatment affected carcass quality (P>0.05), but CHX steers achieved a greater killing out proportion (Pnitrate to the diet or increasing the level of dietary lipid through the use of cold-pressed RSC, did not adversely affect health or performance of finishing beef steers when used within the diets studied.

  1. Methemoglobinaemia in Cardiac Patients on Nitrate Therapy

    Directory of Open Access Journals (Sweden)

    Abdel Aziz A. Ghanem

    2010-06-01

    Full Text Available Background: Methaemoglobinaemia refers to the oxidation of ferrous iron to ferric iron within the haemoglobin molecule, which occurs following oxidative stresses. The subsequent impairment in oxygen transport may lead to progressive hypoxia that is highly dangerous condition especially in borderline patients like the cardiac patient.Objectives: In the present work, authors explore the extent of methaemoglobinaemia in cardiac patients receiving nitrate therapy.Methodology: The study included 970 cardiac patients presented in cardiology department, Mansoura Specialised Medical Hospital, Egypt, in the period from February to July 2009. Patients were taking oral, sublingual, dermal preparation or a combination of two preparations.Results: cases of the study had methemoglobin level 1.1782 ± 0.3476 g/dL with insignificant difference between males and females. Methemoglobin showed positive correlation with carboxyhemogloin and negative correlation with O2 content and O2 saturation. It was significantly higher in cardiac patient with chest infection, anaemia and diabetic patients but didn't differ in hepatic or non hepatic cardiac patients. 3.2% of cardiac patients who receive more than one nitrate preparation (either oral and dermal or oral and sublingual therapy have methemoglobin level significantly higher than those who receive single preparation. There is significant difference in methemoglobin level in cardiac patients complaining of myocardial infarction “MI”, unstable Angina, atrial fibrillation “AF” and hypertensive heart disease “HTN”.Conclusions: It is concluded that commonly used dosages of nitrates are capable of causing elevations of methemoglobin ranged from 0.9 – 5.3 g/dl. Although the elevation in methaemoglobin (MetHb levels was not of routine clinical significance, there was statistically significant increase in MetHb levels in cardiac patients with another pathologic condition as anaemia, diabetes mellitus or chest

  2. Potential of dietary nitrate in angiogenesis.

    Science.gov (United States)

    Rammos, Christos; Luedike, Peter; Hendgen-Cotta, Ulrike; Rassaf, Tienush

    2015-10-26

    Endothelial dysfunction with impaired bioavailability of nitric oxide (NO) is the hallmark in the development of cardiovascular disease. Endothelial dysfunction leads to atherosclerosis, characterized by chronic inflammation of the arterial wall and stepwise narrowing of the vessel lumen. Atherosclerosis causes deprivation of adequate tissue blood flow with compromised oxygen supply. To overcome this undersupply, remodeling of the vascular network is necessary to reconstitute and sustain tissue viability. This physiological response is often not sufficient and therapeutic angiogenesis remains an unmet medical need in critical limb ischemia or coronary artery disease. Feasible approaches to promote blood vessel formation are sparse. Administration of pro-angiogenic factors, gene therapy, or targeting of microRNAs has not yet entered the daily practice. Nitric oxide is an important mediator of angiogenesis that becomes limited under ischemic conditions and the maintenance of NO availability might constitute an attractive therapeutic target. Until recently it was unknown how the organism provides NO under ischemia. In recent years it could be demonstrated that NO can be formed independently of its enzymatic synthesis in the endothelium by reduction of inorganic nitrite under hypoxic conditions. Circulating nitrite derives from oxidation of NO or reduction of inorganic nitrate by commensal bacteria in the oral cavity. Intriguingly, nitrate is a common constituent of our everyday diet and particularly high concentrations are found in leafy green vegetables such as spinach, lettuce, or beetroot. Evidence suggests that dietary nitrate supplementation increases the regenerative capacity of ischemic tissue and that this effect may offer an attractive nutrition-based strategy to improve ischemia-induced revascularization. We here summarize and discuss the regenerative capacity of dietary nitrate on the vascular system.

  3. Potential of dietary nitrate in angiogenesis

    Institute of Scientific and Technical Information of China (English)

    Christos; Rammos; Peter; Luedike; Ulrike; Hendgen-Cotta; Tienush; Rassaf

    2015-01-01

    Endothelial dysfunction with impaired bioavailability of nitric oxide(NO) is the hallmark in the development of cardiovascular disease. Endothelial dysfunction leads to atherosclerosis, characterized by chronic inflammation of the arterial wall and stepwise narrowing of the vessel lumen. Atherosclerosis causes deprivation of adequate tissue blood flow with compromised oxygen supply. To overcome this undersupply, remodeling of the vascular network is necessary to reconstitute and sustain tissue viability. This physiological response is often not sufficient and therapeutic angiogenesis remains an unmet medical need in critical limb ischemia or coronary artery disease. Feasible approaches to promote blood vessel formation are sparse. Administration of pro-angiogenic factors, gene therapy, or targeting of micro RNAs has not yet entered the daily practice. Nitric oxide is an important mediator of angiogenesis that becomes limited under ischemic conditions and the maintenance of NO availability might constitute an attractive therapeutic target. Until recently it was unknown how the organism provides NO under ischemia. In recent years it could be demonstrated that NO can be formed independently of its enzymatic synthesis in the endothelium by reduction of inorganic nitrite under hypoxic conditions. Circulating nitrite derives from oxidation of NO or reduction of inorganic nitrate by commensal bacteria in the oral cavity. Intriguingly, nitrate is a common constituent of our everyday diet and particularly high concentrations are found in leafy green vegetables such as spinach, lettuce, or beetroot. Evidence suggests that dietary nitrate supplementation increases the regenerative capacity of ischemic tissue and that this effect may offer an attractive nutrition-based strategy to improve ischemia-induced revascularization. We here summarize and discuss the regenerative capacity of dietary nitrate on the vascular system.

  4. Calcium – how and why?

    Indian Academy of Sciences (India)

    J K Jaiswal

    2001-09-01

    Calcium is among the most commonly used ions, in a multitude of biological functions, so much so that it is impossible to imagine life without calcium. In this article I have attempted to address the question as to how calcium has achieved this status with a brief mention of the history of calcium research in biology. It appears that during the origin and early evolution of life the Ca2+ ion was given a unique opportunity to be used in several biological processes because of its unusual physical and chemical properties.

  5. Calcium Phosphate Biomaterials: An Update

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Current calcium phosphate (CaP) biomaterials for bone repair, substitution, augmentation and regeneration include hydroxyapatite ( HA ) from synthetic or biologic origin, beta-tricalcium phosphate ( β-TCP ) , biphasic calcium phosphate (BCP), and are available as granules, porous blocks, components of composites (CaP/polymer) cements, and as coatings on orthopedic and dental implants. Experimental calcium phosphate biomaterials include CO3- and F-substituted apatites, Mg-and Zn-substituted β-TCP, calcium phosphate glasses. This paper is a brief review of the different types of CaP biomaterials and their properties such as bioactivity, osteoconductivity, osteoinductivity.

  6. Calcium measurement methods

    Directory of Open Access Journals (Sweden)

    CarloAlberto Redi

    2010-09-01

    Full Text Available Rightly stressed by prof. Wolfgang Walz in the Preface to the series Neuromethods series, the “careful application of methods is probably the most important step in the process of scientific inquiry”. Thus, I strongly suggest to all those interested in calcium signaling and especially to the new-comers in the hot topic of neuroscience (which has so much space even in science-society debate for its implications in legal issues and in the judge-decision process to take profit from this so well edited book. I am saying this since prof. Verkhratsky and prof. Petersen......

  7. Inhibition of tryptase release from human colon mast cells by protease inhibitors

    Institute of Scientific and Technical Information of China (English)

    Shao-Heng He; Hua Xie

    2004-01-01

    AIM: To investigate the ability of protease inhibitors to modulate tryptase release from human colon mast cells.METHODS: Enzymatically dispersed cells from human colon were challenged with anti-IgE or calcium ionophore A23187 in the absence or presence of tryptase and chymase inhibitors,and tryptase release was determined.RESULTS: IgE dependent tryptase release from colon mast cells was inhibited by up to approximately 37%, 40% and 36.6% by chymase inhibitors Z-Ile-Glu-Pro-Phe-CO2Me (ZIGPFM), N-tosyl-L-phenylalanyl-chloromethyl ketone (TPCK), and α1-antitrypsin, respectively. Similarly, the inhibitors of tryptase leupeptin, N-tosyl-L-lysine chloromethyl ketone (TLCK) and lactoferrin were also able to inhibit anti-IgE induced tryptase release by a maximum of 39.4%,47.6% and 36.6%, respectively. The inhibitory actions of chymase inhibitors, but not tryptase inhibitors on colon mast cells were enhanced by preincubation of them with cells for 20 min before challenged with anti-IgE. At a concentration of 10 μg/mL, protamine was able to inhibit anti-IgE and calcium ionophore induced tryptase release. However, at 100 μg/mL, protamine elevated tryptase levels in supernatants.A specific inhibitor of aminopeptidase amastatin had no effect on anti-IgE induced tryptase release. The significant inhibition of calcium ionophore induced tryptase release was also observed with the inhibitors of tryptase and chymase examined. The inhibitors tested by themselves did not stimulate tryptase release from colon mast cells.CONCLUSION: It was demonstrated for the first time that both tryptase and chymase inhibitors could inhibit IgE dependent and calcium ionophore induced tryptase release from dispersed colon mast cells in a concentration dependent of manner, which suggest that they are likely to be developed as a novel class of anti-inflammatory drugs to treat chronic of colitis in man.

  8. Organic Nitrates: A Complex Family of Atmospheric Trace Constituents

    Science.gov (United States)

    Ballschmiter, K.; Fischer, R. G.; Grünert, A.; Kastler, J.; Schneider, M.; Woidich, S.

    2003-04-01

    Biogenic and geogenic hydrocarbons are the precursors of organic nitrates that are formed as tropospheric photo-oxidation products in the presence of NOx. Air chemistry leads to a very complex pattern of nitric acid esters: alkyl nitrates, aryl-alkyl nitrates, and bifunctional nitrates like alkyl dinitrates, hydroxy alkyl nitrates and carbonyl alkyl nitrates. We have analyzed the pattern of organic nitrates in air samples after adsorption/thermal desorption (low volume sampling-LVS) or adsorption/solvent desorption (high volume sampling-HVS) by capillary gas chromatography with electron capture (ECD) and mass spectrometric detection (MSD) using air aliquotes of 100 up to 3000 liters on column. The complexity of the organic nitrates found in air requires a group pre-separation by normal phase liquid chromatography. A detection limit per compound of 0.005 ppt(v) is achieved by our approach. We have synthesized a broad spectrum of organic nitrates as reference compounds. Air samples were taken from central Europe, the US West (Utah, Nevada, California), and the North- and South Atlantic including Antarctica. Levels and patterns of the regional and global occurrence of the various groups of C1-C12 organic nitrates including dinitrates and hydroxy nitrates and nitrates of isoprene (2-methylbutadiene) are presented. Werner G., J. Kastler, R. Looser, K. Ballschmiter: "Organic nitrates of isoprene as atmospheric trace compounds" Angewandte Chemie - International Edition (1999) 38: 1634-1637. Woidich S., O. Froescheis, O. Luxenhofer, K. Ballschmiter: "EI- and NCI-mass spectrometry of arylalkyl nitrates and their occurrence in urban air" Fresenius J. Anal. Chem. (1999) 364 : 91-99. Kastler, J; Jarman, W; Ballschmiter, K.: "Multifunctional organic nitrates as constituents in European and US urban photo-smog" Fresenius J. Anal. Chem. (2000) 368:244-249. Schneider M., K. Ballschmiter: "C3-C14 alkyl nitrates in remote South Atlantic air" Chemosphere (1999) 38: 233-244. Fischer

  9. Regulation of nitrate transport in citrus rootstocks depending on nitrogen availability.

    Science.gov (United States)

    Cerezo, Miguel; Camañes, Gemma; Flors, Víctor; Primo-Millo, Eduardo; García-Agustín, Pilar

    2007-09-01

    Previously, we reported that in Citrus plants, nitrate influx through the plasmalemma of roots cells follows a biphasic pattern, suggesting the existence of at least two different uptake systems, a high and low affinity transport system (HATS and LATS, respectively). Here, we describe a novel inducible high affinity transport system (iHATS). This new nitrate transport system has a high capacity to uptake nitrate in two different Citrus rootstocks (Cleopatra mandarin and Troyer citrange). The iHATS was saturable, showing higher affinity than constitutive high affinity transport system (cHATS) to the substrate NO(3) (-). The V(max) for this saturable component iHATS was higher than cHATS, reaching similar values in both rootstocks.Additionally, we studied the regulation of root NO(3) (-) uptake mediated by both HATS (iHATS and cHATS) and LATS. In both rootstocks, cHATS is constitutive and independent of N-status. Concerning the regulation of iHATS, this system is upregulated by NO(3) (-) and down-regulated by the N status and by NO(3) (-) itself when plants are exposed to it for a longer period of time. LATS in Cleopatra mandarin and Troyer citrange rootstocks is repressed by the N-status.The use of various metabolic uncouplers or inhibitors indicated that NO(3) (-) net uptake mediated by iHATS and LATS was an active transport system in both rootstocks.

  10. Extracellular calcium sensing and extracellular calcium signaling

    Science.gov (United States)

    Brown, E. M.; MacLeod, R. J.; O'Malley, B. W. (Principal Investigator)

    2001-01-01

    , localized changes in Ca(o)(2+) within the ECF can originate from several mechanisms, including fluxes of calcium ions into or out of cellular or extracellular stores or across epithelium that absorb or secrete Ca(2+). In any event, the CaR and other receptors/sensors for Ca(o)(2+) and probably for other extracellular ions represent versatile regulators of numerous cellular functions and may serve as important therapeutic targets.

  11. DETERMINATION OF CORROSION INHIBITOR CRITERIA FOR TYPE III IIIA TANKS DURING SALT DISSOLUTION OPERATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Wiersma, B

    2008-01-04

    Preparation of high level waste for vitrification involves in part the dissolution of salt cake from the carbon steel storage tanks. The salt crystals composing this cake are high in nitrate concentration with the interstitial liquid being high in hydroxide and nitrite concentration. During the salt dissolution process, a stage is reached in which the inhibitors, hydroxide and nitrite, are insufficient to prevent nitrate stress corrosion cracking (SCC) and fall outside the requirements of the corrosion control program. Additional inhibitors, which are necessary to meet the requirements, may be counterproductive to the efficiency of the process and waste minimization. Corrosion testing was initiated to better characterize the necessary inhibitor concentration for high nitrate waste during salt dissolution processing. A four-phase test program is being conducted: (1) electrochemical characterization, (2) accelerated or polarized U-bend testing, (3) long-term (non-polarized) U-bend testing and (4) vapor space U-bend tests. Electrochemical testing, which included cyclic potentiodynamic polarization (CPP), linear polarization resistance (LPR) and open-circuit potential (OCP) measurements, was performed to identify stress corrosion cracking susceptibility, to characterize pitting resistance and to determine the general corrosion rate. Polarized U-bend tests were utilized to assess the effect of minimum inhibitor concentrations and heat treatment on SCC and to determine test parameters for future long-term U-bend testing. Results from CPP, LPR and OCP tests demonstrated that carbon steel formed a protective oxide film and the potential became electropositive during exposure to the waste at all inhibitor concentrations. The tenacity of this film improved as the inhibitor concentration level was increased and the temperature was decreased. This passive film increased the resistance to localized corrosion significantly. Therefore if any of these inhibitor levels are selected

  12. Effect of calcium on adsorption capacity of powdered activated carbon.

    Science.gov (United States)

    Li, Gang; Shang, Junteng; Wang, Ying; Li, Yansheng; Gao, Hong

    2013-12-01

    We investigated the effect of calcium ion on the adsorption of humic acid (HA) (as a target pollutant) by powered activated carbon. The HA adsorption isotherms at different pH and kinetics of two different solutions including HA alone and HA doped Ca(2+), were performed. It was showed that the adsorption capacity of powdered activated carbon (PAC) for HA was markedly enhanced when Ca(2+) was doped into HA. Also, HA and Ca(2+) taken as nitrate were tested on the uptake of each other respectively and it was showed that the adsorbed amounts of both of them were significantly promoted when HA and calcium co-existed. Furthermore, the adsorbed amount of HA slightly decreased with the increasing of Ca(2+) concentration, whereas the amount of calcium increased with the increasing of HA concentration, but all above the amounts without addition. Finally, the change of pH before and after adsorption process is studied. In the two different solutions including HA alone and HA doped Ca(2+), pH had a small rise, but the extent of pH of later solution was bigger.

  13. Superparamagnetic calcium ferrite nanoparticles synthesized using a simple sol-gel method for targeted drug delivery.

    Science.gov (United States)

    Sulaiman, N H; Ghazali, M J; Majlis, B Y; Yunas, J; Razali, M

    2015-01-01

    The calcium ferrite nano-particles (CaFe2O4 NPs) were synthesized using a sol-gel method for targeted drug delivery application. The proposed nano-particles were initially prepared by mixing calcium and iron nitrates that were added with citric acid in order to prevent agglomeration and subsequently calcined at a temperature of 550°C to obtain small particle size. The prepared nanoparticles were characterized by using an XRD (X-ray diffraction), which revealed the configuration of orthorhombic structures of the CaFe2O4 nano-particles. A crystallite size of ~13.59 nm was obtained using a Scherer's formula. Magnetic analysis using a VSM (Vibrating Sample Magnetometer analysis), revealed that the synthesized particles exhibited super-paramagnetic behavior having magnetization saturation of approximately 88.3emu/g. Detailed observation via the scanning electron microscopy (SEM) showed the calcium ferrite nano-particles were spherical in shape.

  14. Carbonyl Alkyl Nitrates as Trace Constituents in Urban Air

    Science.gov (United States)

    Woidich, S.; Gruenert, A.; Ballschmiter, K.

    2003-04-01

    Organic nitrates, esters of nitric acid, significantly contribute to the entire pool of odd nitrogen (NOY) in the atmosphere. Organic nitrates are formed in NO rich air by degradation of alkanes and alkenes initiated by OH and NO3 radicals during daytime and nighttime, respectively. Bifunctional organonitrates like the alkyl dinitrates and hydroxy alkyl nitrates are formed primarily from alkenes. The two main sources for Alkenes are traffic emissions and naturally occurring terpenes. So far a broad spectrum of alkyl dinitrates and hydroxy alkyl nitrates including six different isoprene nitrates has been identified in urban and marine air (1-3). We report here for the first time about the group of C4 C7 carbonyl alkyl nitrates as trace constituents in urban air collected on the campus of the University of Ulm Germany, and in the downtown area of Salt Lake City, Utah. Air sampling was done by high volume sampling (flow rate 25 m3/h) using a layer of 100 g silica gel (particle diameter 0.2 - 0.5 mm) as adsorbent. The organic nitrates were eluted from the silica gel by pentane/acetone (4:1, w/w) and the extract was concentrated to a volume of 500 µL for a group separation using normal phase HPLC. Final analysis was performed by high resolution capillary gas chromatography with electron capture detection as well as by mass selective detection in the (CH4)NCI mode using NO2- = m/e 46 as the indicator mass. The carbonyl alkyl nitrates were identified by self synthesized reference standards . So far we have identified eight non-branched a-carbonyl alkyl nitrates (vicinal carbonyl alkyl nitrates), two b-carbonyl alkyl nitrates and one g-carbonyl alkyl nitrate with carbon chains ranging from C4 to C7. The mixing ratios are between 0.05 and 0.30 ppt(v) for daytime samples and are two to three times higher for samples taken at night. (1) M. Schneider, O. Luxenhofer, Angela Deißler, K. Ballschmiter: 2C1-C15 Alkyl Nitrates, Benzyl Nitrate, and Bifunctional Nitrates

  15. [Nitrate removal by a strain of nitrate-dependent Fe (II) -oxidizing bacteria].

    Science.gov (United States)

    Wang, Hong-Yu; Yang, Kai; Zhang, Qian; Ji, Bin; Chen, Dan; Sun, Yu-Chong; Tian, Jun

    2014-04-01

    A nitrate-dependent Fe(II)-oxidizing bacterial strain, named W5, was isolated from the sediment of the East Lake in Wuhan. Strain W5 was studied for its characteristics of denitrification and nitrogen removal. According to its physiological and biochemical characteristics and the analysis of its 16S rRNA gene sequence, strain W5 was identified as Microbacterium sp. The optimal denitrification performance can be obtained under conditions of NO3(-) -N 40 mg x L(-1), Fe2+ 500 mg x L(-1) and pH 6.8-7.0. After one week of cultivation under optimal conditions, nitrate removal percentage reached 87.0%. During the process of the culture, the nitrite nitrogen concentration was no more than 0.31 mg x L(-1) and there was no ammonia nitrogen production. It was indicated that the nitrate was mostly converted into N2. The consumption rate of Fe2+ was 95.2%.

  16. Negative inotropic action of denbufylline through interfering with the calcium channel independently of its PDE IV inhibitory activity in guinea pig ventricle papillary muscles.

    Science.gov (United States)

    Sanae, F; Ohmae, S; Kobayashi, D; Takag, K; Miyamoto, K

    1996-04-01

    The inotropic actions of xanthine derivatives with long alkyl chains were investigated in guinea pig ventricular papillary muscle. A potent and nonselective phosphodiesterase (PDE) inhibitor, 3-isobutyl-1-methylxanthine, elicited a positive inotropy and inhibited the negative inotropic effects of calcium channel inhibitors, as did a selective PDE III inhibitor, amrinone, and these effects were canceled by a protein kinase inhibitor, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89). However, 1,3-di-n-butyl-7-(2'oxopropyl)xanthine (denbufylline) and 1-n-butyl-3-n-propylxanthine (XT-044), which have potent and selective PDE IV-inhibitory activities, showed negative inotropic actions that became more potent in the presence of H-89. Denbufylline abolished the late restoration phase induced by ryanodine. This xanthine derivative attenuated the effects of both the calcium channel acting agents Bay K 8644 and verapamil, without interaction with caffeine and dihydropyridine calcium channel inhibitors, and denbufylline had little direct influence on the specific binding of [(3)H]azidopine and [(3)H]desmethoxyverapamil to cardiac membranes. A nonxanthine PDE IV inhibitor, Ro 20-1724, did not affect the inotropic actions of calcium channel inhibitors. The attenuation by denbufylline or XT-044 of the negative inotropic action of verapamil was not influenced by treatment with H-89. These results suggest that in the ventricular papillary muscle, these xanthine derivatives elicit negative inotropy by acting on a verapamil-sensitive site of the calcium channel without involving their PDE-inhibitory activity.

  17. Vitamin D, Calcium, and Bone Health

    Science.gov (United States)

    ... in Balance › Vitamin D, Calcium, and Bone Health Vitamin D, Calcium, and Bone Health March 2012 Download ... also helps keep your bones strong. Why are vitamin D and calcium important to bone health? Vitamin ...

  18. Calcium, vitamin D, and your bones

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000490.htm Calcium, vitamin D, and your bones To use the sharing ... and maintain strong bones. How Much Calcium and Vitamin D do I Need? Amounts of calcium are ...

  19. Growing patterns to produce 'nitrate-free' lettuce (Lactuca sativa).

    Science.gov (United States)

    Croitoru, Mircea Dumitru; Muntean, Daniela-Lucia; Fülöp, Ibolya; Modroiu, Adriana

    2015-01-01

    Vegetables can contain significant amounts of nitrate and, therefore, may pose health hazards to consumers by exceeding the accepted daily intake for nitrate. Different hydroponic growing patterns were examined in this work in order to obtain 'nitrate-free lettuces'. Growing lettuces on low nitrate content nutrient solution resulted in a significant decrease in lettuces' nitrate concentrations (1741 versus 39 mg kg(-1)), however the beneficial effect was cancelled out by an increase in the ambient temperature. Nitrate replacement with ammonium was associated with an important decrease of the lettuces' nitrate concentration (from 1896 to 14 mg kg(-1)) and survival rate. An economically feasible method to reduce nitrate concentrations was the removal of all inorganic nitrogen from the nutrient solution before the exponential growth phase. This method led to lettuces almost devoid of nitrate (10 mg kg(-1)). The dried mass and calcinated mass of lettuces, used as markers of lettuces' quality, were not influenced by this treatment, but a small reduction (18%, p lettuces and their modifications are also discussed in the paper. It is possible to obtain 'nitrate-free' lettuces in an economically feasible way.

  20. Nitrate removal using different carbon substrates in a laboratory model.

    Science.gov (United States)

    Hashemi, Seyyed Ebrahim; Heidarpour, Manouchehr; Mostafazadeh-Fard, Behrouz

    2011-01-01

    Agricultural fields have been frequently identified as major contributors of nitrate leaching into surface and ground waters. Tile drains can act as direct pathways, transferring leached nitrate to surface water. Bioreactor filters are useful for the removal of nitrate from drainage waters; however, these filters require an external carbon supply to sustain denitrification. In this study, four organic carbon sources including wood, barley straw, rice husks, and date palm leaf, were used to enhance denitrification and the effects of water velocity and influent nitrate concentration on the nitrate removal were evaluated. Cumulative nitrate removal was highest for the date palm leaf treatments and was lowest for the wood treatments. The effects were in decreasing order for date palm leaf, barley straw, rice husks, and wood, respectively. The performance of the biofilters improved with increasing influent nitrate concentration and decreasing water velocity, allowing for high nitrate removal rates to be achieved. The results showed that all of the treatments had reduced the effluent nitrate concentrations below the USEPA maximum contaminant level for drinking water of 45 mg L(-1) nitrate at the end of the study.

  1. Nitrate removal using Brevundimonas diminuta MTCC 8486 from ground water.

    Science.gov (United States)

    Kavitha, S; Selvakumar, R; Sathishkumar, M; Swaminathan, K; Lakshmanaperumalsamy, P; Singh, A; Jain, S K

    2009-01-01

    Brevundimonas diminuta MTCC 8486, isolated from marine soil of coastal area of Trivandrum, Kerala, was used for biological removal of nitrate from ground water collected from Kar village of Pali district, Rajasthan. The organism was found to be resistance for nitrate up to 10,000 mg L(-1). The optimum growth conditions for biological removal of nitrate were established in batch culture. The effect of carbon sources on nitrate removal was investigated using mineral salt medium (MSM) containing 500 mg L(-1) of nitrate to select the most effective carbon source. Among glucose and starch as carbon source, glucose at 1% concentration increased the growth (182+/-8.24 x 10(4) CFU mL(-1)) and induced maximum nitrate reduction (86.4%) at 72 h. The ground water collected from Kar village, Pali district of Rajasthan containing 460+/-5.92 mg L(-1) of nitrate was subjected to three different treatment processes in pilot scale (T1 to T3). Higher removal of nitrate was observed in T2 process (88%) supplemented with 1% glucose. The system was scaled up to 10 L pilot scale treatment plant. At 72 h the nitrate removal was observed to be 95% in pilot scale plant. The residual nitrate level (23+/-0.41 mg L(-1)) in pilot scale treatment process was found to be below the permissible limit of WHO.

  2. Reductive denitrification of nitrate by scrap iron filings

    Institute of Scientific and Technical Information of China (English)

    HAO Zhi-wei; XU Xin-hua; WANG Da-hui

    2005-01-01

    Reduction of nitrate by zero-valent iron is a highly exergonic reaction that has long been known to occur. Use of scrap iron filings (SIF) as the PRB (Permeable Reactive Barrier) material can be used to recycle certain by-products, and identify cheaper replacements for expensive conventional PRB materials, especially pure metallic iron. The feasibility of reductive denitrification of nitrate by SIF was studied by batch experiments. Operational parameters such as pH value, SIF dosage and initial concentration of nitrate were investigated. The removal efficiency of nitrate reached 80% under the conditions of pH of 2.5, nitrate initial concentration of 45 mg/L and SIF dosage of 100 g/L within 4 h. Results indicated that nitrate removal is inversely related to pH. Low pH value condition favors for the nitrate transformation. Different from the results of others who studied nitrate reduction using iron powder, we found that there was a lag time before nitrate reduction occurs, even at low pH. Finally, the possible mechanism of nitrate reduction by Fe0 is discussed.

  3. Nitrate ammonification in mangrove soils: a hidden source of nitrite?

    KAUST Repository

    Balk, Melike

    2015-03-02

    Nitrate reduction is considered to be a minor microbial pathway in the oxidation of mangrove-derived organic matter due to a limited supply of nitrate in mangrove soils. At a limited availability of this electron acceptor compared to the supply of degradable carbon, nitrate ammonification is thought to be the preferential pathway of nitrate reduction. Mangrove forest mutually differ in their productivity, which may lead to different available carbon to nitrate ratios in their soil. Hence, nitrate ammonification is expected to be of more importance in high- compared to low-productive forests. The hypothesis was tested in flow-through reactors that contain undisturbed mangrove soils from high-productive Avicennia germinans and Rhizophora mangle forests in Florida and low-productive Avicennia marina forests in Saudi Arabia. Nitrate was undetectable in the soils from both regions. It was assumed that a legacy of nitrate ammonification would be reflected by a higher ammonium production from these soils upon the addition of nitrate. Unexpectedly, the soils from the low-productive forests in Saudi Arabia produced considerably more ammonium than the soils from the high-productive forests in Florida. Hence, other environmental factors than productivity must govern the selection of nitrate ammonification or denitrification. A rather intriguing observation was the 1:1 production of nitrite and ammonium during the consumption of nitrate, more or less independent from sampling region, location, sampling depth, mangrove species and from the absence or presence of additional degradable carbon. This 1:1 ratio points to a coupled production of ammonium and nitrite by one group of nitrate-reducing microorganisms. Such a production of nitrite will be hidden by the presence of active nitrite-reducing microorganisms under the nitrate-limited conditions of most mangrove forest soils.

  4. Nitrate ammonification in mangrove soils: a hidden source of nitrite?

    Science.gov (United States)

    Balk, Melike; Laverman, Anniet M; Keuskamp, Joost A; Laanbroek, Hendrikus J

    2015-01-01

    Nitrate reduction is considered to be a minor microbial pathway in the oxidation of mangrove-derived organic matter due to a limited supply of nitrate in mangrove soils. At a limited availability of this electron acceptor compared to the supply of degradable carbon, nitrate ammonification is thought to be the preferential pathway of nitrate reduction. Mangrove forest mutually differ in their productivity, which may lead to different available carbon to nitrate ratios in their soil. Hence, nitrate ammonification is expected to be of more importance in high- compared to low-productive forests. The hypothesis was tested in flow-through reactors that contain undisturbed mangrove soils from high-productive Avicennia germinans and Rhizophora mangle forests in Florida and low-productive Avicennia marina forests in Saudi Arabia. Nitrate was undetectable in the soils from both regions. It was assumed that a legacy of nitrate ammonification would be reflected by a higher ammonium production from these soils upon the addition of nitrate. Unexpectedly, the soils from the low-productive forests in Saudi Arabia produced considerably more ammonium than the soils from the high-productive forests in Florida. Hence, other environmental factors than productivity must govern the selection of nitrate ammonification or denitrification. A rather intriguing observation was the 1:1 production of nitrite and ammonium during the consumption of nitrate, more or less independent from sampling region, location, sampling depth, mangrove species and from the absence or presence of additional degradable carbon. This 1:1 ratio points to a coupled production of ammonium and nitrite by one group of nitrate-reducing microorganisms. Such a production of nitrite will be hidden by the presence of active nitrite-reducing microorganisms under the nitrate-limited conditions of most mangrove forest soils.

  5. Vitamin K Supplementation and the Progression of Coronary Artery Calcium in Older Men and Women

    Science.gov (United States)

    Coronary artery calcium (CAC) is an independent predictor of cardiovascular disease. A preventive role for vitamin K in CAC progression has been proposed based on the properties of matrix Gla protein (MGP) as a vitamin K-dependent calcification inhibitor. The objective of this study was to determine...

  6. Mechanisms involved in calcium deficiency development in tomato fruit in response to gibberellins

    Science.gov (United States)

    Although gibberellins (GAs) have been shown to induce the calcium deficiency disorder, blossom-end rot (BER), development in tomato fruit (Solanum lycopersicum), the mechanisms involved remain largely unexplored. Our objectives were to better understand how GAs and a GA biosynthesis inhibitor affect...

  7. Protein nitration in biological aging: proteomic and tandem mass spectrometric characterization of nitrated sites.

    Science.gov (United States)

    Kanski, Jaroslaw; Schöneich, Christian

    2005-01-01

    Proteomic techniques for the identification of 3-nitrotyrosine-containing proteins in various biological systems are described with emphasis on the direct mass spectrometric detection and sequencing of 3-nitrotyrosine-containing peptides. Strengths and weaknesses of various separation and mass spectrometric techniques are discussed. Some examples for the MS/MS analysis of nitrated peptides obtained from aging rat heart and skeletal muscle are provided, such as nitration of Tyr105 of the mitochondrial electron-transfer flavoprotein and Tyr14 of creatine kinase.

  8. Vitamin D and Intestinal Calcium Absorption

    OpenAIRE

    Christakos, Sylvia; Dhawan, Puneet; Porta, Angela; Mady, Leila J.; Seth, Tanya

    2011-01-01

    The principal function of vitamin D in calcium homeostasis is to increase calcium absorption from the intestine. Calcium is absorbed by both an active transcellular pathway, which is energy dependent, and by a passive paracellular pathway through tight junctions. 1,25Dihydroxyvitamin D3 (1,25(OH)2D3) the hormonally active form of vitamin D, through its genomic actions, is the major stimulator of active intestinal calcium absorption which involves calcium influx, translocation of calcium throu...

  9. Mammary-Specific Ablation of the Calcium-Sensing Receptor During Lactation Alters Maternal Calcium Metabolism, Milk Calcium Transport, and Neonatal Calcium Accrual

    OpenAIRE

    Mamillapalli, Ramanaiah; VanHouten, Joshua; Dann, Pamela; Bikle, Daniel; Chang, Wenhan; Brown, Edward; Wysolmerski, John

    2013-01-01

    To meet the demands for milk calcium, the lactating mother adjusts systemic calcium and bone metabolism by increasing dietary calcium intake, increasing bone resorption, and reducing renal calcium excretion. As part of this adaptation, the lactating mammary gland secretes PTHrP into the maternal circulation to increase bone turnover and mobilize skeletal calcium stores. Previous data have suggested that, during lactation, the breast relies on the calcium-sensing receptor (CaSR) to coordinate ...

  10. Calcium-dependent 86 Rb efflux and ethanol intoxication: studies of human red blood cells and rodent brain synaptosomes.

    Science.gov (United States)

    Yamamoto, H A; Harris, R A

    1983-04-08

    Effects of ethanol on calcium-dependent potassium efflux were investigated in red blood cells (RBC) from humans and brain synaptosomes from rats and mice. 86 Rb was used as a tracer for potassium. Synaptosomes and RBC were lysed and resealed with 86 Rb and calcium-EGTA buffers to regulate intracellular levels of ionized calcium. In vitro addition of ethanol (100 mM) stimulated the calcium-dependent 86 Rb efflux of synaptosomes. This stimulation was blocked by apamin, an inhibitor of the calcium-dependent potassium current of nerve cells. In addition, intracerebroventricular injection of apamin inhibited ethanol-induced narcosis in mice, providing behavioral evidence for the importance of calcium-stimulated potassium efflux in alcohol intoxication. In vitro addition of ethanol, propanol or butanol increased calcium-dependent 86 Rb efflux of human RBC at low concentrations of free calcium, but did not change the calcium-independent efflux of 86 Rb. These results suggest that the calcium-dependent 86 Rb efflux of nerve endings may have an important role in the pharmacological and toxicological effects of ethanol.

  11. 21 CFR 184.1191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of... soda process”; (2) By precipitation of calcium carbonate from calcium hydroxide in the...

  12. Evaluating Ecosystem Services for Reducing Groundwater Nitrate Contamination: Nitrate Attenuation in the Unsaturated and Saturated Zones

    Science.gov (United States)

    Wang, J.

    2013-12-01

    Nitrates are the most common type of groundwater contamination in agricultural regions. Environmental policies targeting nitrates have focused on input control (e.g., restricted fertilizer application), intermediate loads control (e.g., reduce nitrate leached from crop fields), and final loads control (e.g., reduce catchment nitrate loads). Nitrate loads can be affected by hydrological processes in both unsaturated and saturated zones. Although many of these processes have been extensively investigated in literature, they are commonly modeled as exogenous to farm management. A couple of recent studies by scientists from the Lawrence Livermore National Laboratory show that in some situations nitrate attenuation processes in the unsaturated/saturated zone, particularly denitrification, can be intensified by certain management practices to mitigate nitrate loads. Therefore, these nitrate attenuation processes can be regarded as a set of ecosystem services that farmers can take advantage of to reduce their cost of complying with environmental policies. In this paper, a representative California dairy farm is used as a case study to show how such ecosystem attenuation services can be framed within the farm owner's decision-making framework as an option for reducing groundwater nitrate contamination. I develop an integrated dynamic model, where the farmer maximizes discounted net farm profit over multiple periods subject to environmental regulations. The model consists of three submodels: animal-waste-crop, hydrologic, and economic model. In addition to common choice variables such as irrigation, fertilization, and waste disposal options, the farmer can also endogenously choose from three water sources: surface water, deep groundwater (old groundwater in the deep aquifer that is not affected by farm effluent in the short term), and shallow groundwater (drainage water that can be recycled via capture wells at the downstream end of the farm). The capture wells not only

  13. Accumulation of Nitrate in Vegetables and Its Possible Implications to Human Health

    Institute of Scientific and Technical Information of China (English)

    DU Shao-ting; ZHANG Yong-song; LIN Xian-yong

    2007-01-01

    In recent times, there are two kinds of completely opposite viewpoints about the impacts of nitrate on human health. To further objectively understand the effects of nitrate on human health, both of harmfulness and possible benefits of nitrate to human body, it is discussed in this review from the aspects of nitrate accumulation in vegetables, the source of nitrate ingested into human body, and the transformation of nitrate in human body, as well as the pathogenesis and physiological functions of nitrate metabolism.

  14. Nitration of pollen aeroallergens by nitrate ion in conditions simulating the liquid water phase of atmospheric particles.

    Science.gov (United States)

    Ghiani, Alessandra; Bruschi, Maurizio; Citterio, Sandra; Bolzacchini, Ezio; Ferrero, Luca; Sangiorgi, Giorgia; Asero, Riccardo; Perrone, Maria Grazia

    2016-12-15

    Pollen aeroallergens are present in atmospheric particulate matter (PM) where they can be found in coarse biological particles such as pollen grains (aerodynamic diameter dae>10μm), as well as fragments in the finest respirable particles (PM2.5; dae<2.5μm). Nitration of tyrosine residues in pollen allergenic proteins can occur in polluted air, and inhalation and deposition of these nitrated proteins in the human respiratory tract may lead to adverse health effects by enhancing the allergic response in population. Previous studies investigated protein nitration by atmospheric gaseous pollutants such as nitrogen dioxide and ozone. In this work we report, for the first time, a study on protein nitration by nitrate ion in aqueous solution, at nitrate concentrations and pH conditions simulating those occurring in the atmospheric aerosol liquid water phase. Experiments have been carried out on the Bovine serum albumin (BSA) protein and the recombinant Phleum pratense allergen (Phl p 2) both in the dark and under UV-A irradiation (range 4-90Wm(-2)) to take into account thermal and/or photochemical nitration processes. For the latter protein, modifications in the allergic response after treatment with nitrate solutions have been evaluated by immunoblot analyses using sera from grass-allergic patients. Experimental results in bulk solutions showed that protein nitration in the dark occurs only in dilute nitrate solutions and under very acidic conditions (pH<3 for BSA; pH<2.2 for Phl p 2), while nitration is always observed (at pH0.5-5) under UV-A irradiation, both in dilute and concentrated nitrate solutions, being significantly enhanced at the lowest pH values. In some cases, protein nitration resulted in an increase of the allergic response.

  15. Glucose elevates NITRATE TRANSPORTER2.1 protein levels and nitrate transport activity independently of its HEXOKINASE1-mediated stimulation of NITRATE TRANSPORTER2.1 expression.

    Science.gov (United States)

    de Jong, Femke; Thodey, Kate; Lejay, Laurence V; Bevan, Michael W

    2014-01-01

    Mineral nutrient uptake and assimilation is closely coordinated with the production of photosynthate to supply nutrients for growth. In Arabidopsis (Arabidopsis thaliana), nitrate uptake from the soil is mediated by genes encoding high- and low-affinity transporters that are transcriptionally regulated by both nitrate and photosynthate availability. In this study, we have studied the interactions of nitrate and glucose (Glc) on gene expression, nitrate transport, and growth using glucose-insensitive2-1 (gin2-1), which is defective in sugar responses. We confirm and extend previous work by showing that HEXOKINASE1-mediated oxidative pentose phosphate pathway (OPPP) metabolism is required for Glc-mediated NITRATE TRANSPORTER2.1 (NRT2.1) expression. Treatment with pyruvate and shikimate, two products derived from intermediates of the OPPP that are destined for amino acid production, restores wild-type levels of NRT2.1 expression, suggesting that metabolites derived from OPPP metabolism can, together with Glc, directly stimulate high levels of NRT2.1 expression. Nitrate-mediated NRT2.1 expression is not influenced by gin2-1, showing that Glc does not influence NRT2.1 expression through nitrate-mediated mechanisms. We also show that Glc stimulates NRT2.1 protein levels and transport activity independently of its HEXOKINASE1-mediated stimulation of NRT2.1 expression, demonstrating another possible posttranscriptional mechanism influencing nitrate uptake. In gin2-1 plants, nitrate-responsive biomass growth was strongly reduced, showing that the supply of OPPP metabolites is essential for assimilating nitrate for growth.

  16. Evolution of the Calcium Paradigm: The Relation between Vitamin D, Serum Calcium and Calcium Absorption

    Directory of Open Access Journals (Sweden)

    Borje E. Christopher Nordin

    2010-09-01

    Full Text Available Osteoporosis is the index disease for calcium deficiency, just as rickets/osteomalacia is the index disease for vitamin D deficiency, but there is considerable overlap between them. The common explanation for this overlap is that hypovitaminosis D causes malabsorption of calcium which then causes secondary hyperparathyroidism and is effectively the same thing as calcium deficiency. This paradigm is incorrect. Hypovitaminosis D causes secondary hyperparathyroidism at serum calcidiol levels lower than 60 nmol/L long before it causes malabsorption of calcium because serum calcitriol (which controls calcium absorption is maintained until serum calcidiol falls below 20 nmol/L. This secondary hyperparathyroidism, probably due to loss of a “calcaemic” action of vitamin D on bone first described in 1957, destroys bone and explains why vitamin D insufficiency is a risk factor for osteoporosis. Vitamin D thus plays a central role in the maintenance of the serum (ionised calcium, which is more important to the organism than the preservation of the skeleton. Bone is sacrificed when absorbed dietary calcium does not match excretion through the skin, kidneys and bowel which is why calcium deficiency causes osteoporosis in experimental animals and, by implication, in humans.

  17. Impact of weather variability on nitrate leaching

    Science.gov (United States)

    Richards, Karl; Premrov, Alina; Hackett, Richard; Coxon, Catherine

    2016-04-01

    The loss of nitrate (NO3 - N) to water via leaching and overland flow contributes to eutrophication of freshwaters, transitional and near coastal waters with agriculture contributing significantly to nitrogen (N) loading to these water. Environmental regulations, such as the Nitrates and Water Framework Directives, have increased constraints on farmers to improve N management in regions at risk of NO3--N loss to water. In addition, farmers also have to manage their systems within a changing climate as the imapcts of climate change begin to impact resulting in more frequent extreme events such as floods and droughts. The objective of this study was to investigate the link between weather volatility and the concentration of leached NO3--N spring barley. Leaching was quantified under spring barley grown on a well-drained, gravelly sandy soil using ceramic cup samplers over 6 drainage years under the same farming practices and treatments. Soil solution NO3--N concentrations under spring barley grown by conventional inversion ploughing and reduced tillage were compared to weather parameters over the period. Weather was recorded at a national Met Eireann weather station on site. Soil solution NO3--N varied significantly between years. Within individual years NO3--N concentrations varied over the drainage season, with peak concentrations generally observed in the autumn time, decreasing thereafter. Under both treatments there was a three-fold difference in mean annual soil solution NO3--N concentration over the 6 years with no change in the agronomic practices (crop type, tillage type and fertiliser input). Soil solution nitrate concentrations were significantly influenced by weather parameters such as rainfall, effective drainage and soil moisture deficit. The impact of climate change in Ireland could lead to increased NO3--N loss to water further exacerbating eutrophication of sensitive estuaries. The increased impact on eutrophication of waters, related to climatic

  18. Laboratory study of nitrate photolysis in Antarctic snow

    DEFF Research Database (Denmark)

    Berhanu, Tesfaye A.; Meusinger, Carl; Erbland, Joseph;

    2014-01-01

    Atmospheric nitrate is preserved in Antarctic snow firn and ice. However, at low snow accumulation sites, post-depositional processes induced by sunlight obscure its interpretation. The goal of these studies (see also Paper I by Meusinger et al. [" Laboratory study of nitrate photolysis...... in Antarctic snow. I. Observed quantum yield, domain of photolysis, and secondary chemistry," J. Chem. Phys. 140, 244305 (2014)]) is to characterize nitrate photochemistry and improve the interpretation of the nitrate ice core record. Naturally occurring stable isotopes in nitrate (15N, 17O, and 18O) provide...... additional information concerning post-depositional processes. Here, we present results from studies of the wavelength-dependent isotope effects from photolysis of nitrate in a matrix of natural snow. Snow from Dome C, Antarctica was irradiated in selected wavelength regions using a Xe UV lamp and filters...

  19. Limestone reaction in calcium aluminate cement–calcium sulfate systems

    Energy Technology Data Exchange (ETDEWEB)

    Bizzozero, Julien, E-mail: julien.bizzozero@gmail.com; Scrivener, Karen L.

    2015-10-15

    This paper reports a study of ternary blends composed of calcium aluminate cement, calcium sulfate hemihydrate and limestone. Compressive strength tests and hydration kinetics were studied as a function of limestone and calcium sulfate content. The phase evolution and the total porosity were followed and compared to thermodynamic simulation to understand the reactions involved and the effect of limestone on these binders. The reaction of limestone leads to the formation of hemicarboaluminate and monocarboaluminate. Increasing the ratio between sulfate and aluminate decreases the extent of limestone reaction.

  20. Characterization of alkali-metal and alkaline-earth nitrates by vibrational spectroscopy

    Directory of Open Access Journals (Sweden)

    Martínez, S.

    1992-09-01

    Full Text Available Infrared spectra of sodium and potassium alkaline-metal nitrates and magnesium and calcium alkali-earth nitrates in solid phase had been recorded in order to assign the fundamental bands. The influence of the dispersal médium (alkaline halide, employed in the solid sample preparation have been discussed. The quantitative measurements of the band in ten sities at 1387 cm-1 (present in the I.R. spectra of the four nitrates in KBr médium allowed us to determine the Lambert-Beer law slopes for each compound. These values are differents (bearing in mind experimental random errors, so we have could to affirm the nonexistence of solid solution between the nitrate and the alkaline halide médium. The L-B law obtained by us can be used for the Identification differentiation and quantitative analysis of these nitrates in solid phase, even if they are present in a very low concentration.

    Se ha realizado la asignación de los espectros infrarrojo (IR de los nitratos alcalinos, sódico y potásico, y de los alcalinotérreos, magnésico y cálcico, en estado sólido. Se ha visto la influencia del medio dispersante (haluro alcalino, utilizado en la preparación de la muestra sólida. El estudio cuantitativo de la absorbencia de la banda a 1.387 cm-1 (presente en los espectros IR de los cuatro nitratos en medio KBr permite determinar las pendientes de la Ley de Lambert-Beer Se comprueba que dichas pendientes son diferentes lo que conduce a poder afirmar que no se produce disolución sólida entre el KBr y el nitrato alcalino o alcalinotérreo. La determinación de la ley de Lambert-Beer permite la identificación y el análisis cualitativo y cuantitativo por espectroscopia IR de estos nitratos cuando están presentes en bajas concentraciones en muestras sólidas.

  1. End organ protection by calcium-channel blockers.

    Science.gov (United States)

    Tzivoni, D

    2001-02-01

    In recent years, much attention has been given to end organ protection by antihypertensive, anti-heart failure, and anti-ischemic medications. This review describes the available information on end organ protection by calcium-channel blockers (CCBs). In normotensive patients and patients with hypertension treated with long-acting dihydropyridines, medial thickness was thinner than in patients treated with atenolol or in untreated hypertensive patients. Long-term treatment was associated with significant reduction in left ventricular mass. Calcium-channel blockers also improved endothelial-dependent relaxation and reversed the vasoconstrictive response to nitric oxide inhibitors. In diabetic patients, CCBs were effective in preserving kidney function and microalbuminurea. The combination of angiotensin-converting enzyme (ACE) inhibitors and CCBs was more effective than ACE inhibitors alone in preserving kidney function. In animal experiments, CCBs prevented development of coronary atheroschlerosis; however, in humans only limited data are available on their antiatherogenic effect. Some studies suggest that CCBs exert antiplatelets properties and may therefore be beneficial in patients with coronary artery disease.

  2. NITRATE REMOVAL FROM WATER USING SURFACE-MODIFIED ULTRAFILTRATION MEMBRANES

    OpenAIRE

    Habuda-Stanić, Mirna; Nujić, Marija; Santo, Vera

    2014-01-01

    Elevated nitrate concentrations in natural water sources are a worldwide concern due to the extensive levels of soil N-fertilization. This study investigates three commercially available polyethersulfone (PES) ultrafiltration (UF) membranes with different molecular weight cut-offs (5, 10, and 30 kDa), which we modified with a cationic surfactant, cetylpyridinium chloride to improve their nitrate removal. The nitrate removal efficiency of these membranes was examinated as functions of initial ...

  3. Endogenously nitrated proteins in mouse brain: links to neurodegenerative disease.

    Science.gov (United States)

    Sacksteder, Colette A; Qian, Wei-Jun; Knyushko, Tatyana V; Wang, Haixing; Chin, Mark H; Lacan, Goran; Melega, William P; Camp, David G; Smith, Richard D; Smith, Desmond J; Squier, Thomas C; Bigelow, Diana J

    2006-07-04

    Increased abundance of nitrotyrosine modifications of proteins have been documented in multiple pathologies in a variety of tissue types and play a role in the redox regulation of normal metabolism. To identify proteins sensitive to nitrating conditions in vivo, a comprehensive proteomic data set identifying 7792 proteins from a whole mouse brain, generated by LC/LC-MS/MS analyses, was used to identify nitrated proteins. This analysis resulted in the identification of 31 unique nitrotyrosine sites within 29 different proteins. More than half of the nitrated proteins that have been identified are involved in Parkinson's disease, Alzheimer's disease, or other neurodegenerative disorders. Similarly, nitrotyrosine immunoblots of whole brain homogenates show that treatment of mice with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), an experimental model of Parkinson's disease, induces an increased level of nitration of the same protein bands observed to be nitrated in brains of untreated animals. Comparing sequences and available high-resolution structures around nitrated tyrosines with those of unmodified sites indicates a preference of nitration in vivo for surface accessible tyrosines in loops, a characteristic consistent with peroxynitrite-induced tyrosine modification. In addition, most sequences contain cysteines or methionines proximal to nitrotyrosines, contrary to suggestions that these amino acid side chains prevent tyrosine nitration. More striking is the presence of a positively charged moiety near the sites of nitration, which is not observed for non-nitrated tyrosines. Together, these observations suggest a predictive tool of functionally important sites of nitration and that cellular nitrating conditions play a role in neurodegenerative changes in the brain.

  4. Association of cardiac injury with iron-increased oxidative and nitrative modifications of the SERCA2a isoform of sarcoplasmic reticulum Ca(2+)-ATPase in diabetic rats.

    Science.gov (United States)

    Li, Xueli; Li, Wenliang; Gao, Zhonghong; Li, Hailing

    2016-08-01

    The role of iron in the etiology of diabetes complications is not well established. Thus, this study was performed to test whether the iron-induced increase of oxidative/nitrative damage is involved in SERCA2a-related diabetic heart complication. Four randomly divided groups of rats were used: normal control group; iron overload group; diabetes group, and diabetic plus iron overload group. Iron supplementation stimulated cardiomyocyte hypertrophy and led to an increase in cardiac protein carbonyls, nitrotyrosine (3-NT) formation, and iNOS protein expression, thus resulting in abnormal myocardium calcium homeostasis of diabetic rats. The levels of SECA2a oxidation/nitration were significantly increased in the iron overload diabetic rats, along with a decrease in SECA2a expression and activity. In order to elucidate the possible role of iron in SERCA2a dysfunction, the effects of iron (Fe(3+) or hemin) on peroxynitrite (ONOO(-)) induced SERCA2a oxidation and nitration were further investigated in vitro. It was found that tyrosine nitration played more important role in SERCA2a inactivation than thiol oxidation. These results present a potential mechanism in which iron exacerbates the diabetes-induced oxidative/nitrative modification of SERCA2a, which may cause functional deficits in the myocyte associated with diabetic cardiac dysfunction. Our findings may help to further understand the role of iron in the pathogenesis of diabetic complications.

  5. Calcium-regulated import of myosin IC into the nucleus.

    Science.gov (United States)

    Maly, Ivan V; Hofmann, Wilma A

    2016-06-01

    Myosin IC is a molecular motor involved in intracellular transport, cell motility, and transcription. Its mechanical properties are regulated by calcium via calmodulin binding, and its functions in the nucleus depend on import from the cytoplasm. The import has recently been shown to be mediated by the nuclear localization signal located within the calmodulin-binding domain. In the present paper, it is demonstrated that mutations in the calmodulin-binding sequence shift the intracellular distribution of myosin IC to the nucleus. The redistribution is displayed by isoform B, described originally as the "nuclear myosin," but is particularly pronounced with isoform C, the normally cytoplasmic isoform. Furthermore, experimental elevation of the intracellular calcium concentration induces a rapid import of myosin into the nucleus. The import is blocked by the importin β inhibitor importazole. These findings are consistent with a mechanism whereby calmodulin binding prevents recognition of the nuclear localization sequence by importin β, and the steric inhibition of import is released by cell signaling leading to the intracellular calcium elevation. The results establish a mechanistic connection between the calcium regulation of the motor function of myosin IC in the cytoplasm and the induction of its import into the nucleus. © 2016 Wiley Periodicals, Inc.

  6. Atomic structure of intracellular amorphous calcium phosphate deposits.

    Science.gov (United States)

    Betts, F; Blumenthal, N C; Posner, A S; Becker, G L; Lehninger, A L

    1975-06-01

    The radial distribution function calculated from x-ray diffraction of mineralized cytoplasmic structures isolated from the hepatopancreas of the blue crab (Callinectes sapidus) is very similar to that previously found for synthetic amorphous calcium phosphate. Both types of mineral apparently have only short-range atomic order, represented as a neutral ion cluster of about 10 A in longest dimension, whose probable composition is expressed by the formula Ca9(PO4)6. The minor differences observed are attributed to the presence in the biological mineral of significant amounts of Mg-2+ and ATP. Synthetic amorphous calcium phosphate in contact with a solution containing an amount of ATP equivalent to that of the biological mineral failed to undergo conversion to the thermodynamically more stable hydroxyapatite. The amorphous calcium phosphate of the cytoplasmic mineral granules is similarly stable, and does not undergo conversion to hydroxyapatite, presumably owing to the presence of ATP and Mg-2+, known in inhibitors of the conversion process. The physiological implications of mineral deposits consisting of stabilized calcium phosphate ion clusters are discussed.

  7. Significant accumulation of nitrate in Chinese semi-humid croplands

    Science.gov (United States)

    Zhou, Junyu; Gu, Baojing; Schlesinger, William H.; Ju, Xiaotang

    2016-04-01

    Soil nitrate is important for crop growth, but it can also leach to groundwater causing nitrate contamination, a threat to human health. Here, we report a significant accumulation of soil nitrate in Chinese semi-humid croplands based upon more than 7000 samples from 141 sites collected from 1994 to 2015. In the 0-4 meters depth of soil, total nitrate accumulation reaches 453 ± 39, 749 ± 75, 1191 ± 89, 1269 ± 114, 2155 ± 330 kg N ha-1 on average in wheat, maize, open-field vegetables (OFV), solar plastic-roofed greenhouse vegetables (GHV) and orchard fields, respectively. Surprisingly, there is also a comparable amount of nitrate accumulated in the vadose-zone deeper than 4 meters. Over-use of N fertilizer (and/or manure) and a declining groundwater table are the major causes for this huge nitrate reservoir in the vadose-zone of semi-humid croplands, where the nitrate cannot be denitrified due to the presence of oxygen and lack of carbon sources. Future climatic change with more extreme rainfall events would increase the risk of accumulated nitrate moving downwards and threatening groundwater nitrate contamination.

  8. Hot Spots and Persistence of Nitrate in Aquifers Across Scales

    Directory of Open Access Journals (Sweden)

    Dipankar Dwivedi

    2016-01-01

    Full Text Available Nitrate-N (NO3 -- N is one of the most pervasive contaminants in groundwater. Nitrate in groundwater exhibits long-term behavior due to complex interactions at multiple scales among various geophysical factors, such as sources of nitrate-N, characteristics of the vadose zone and aquifer attributes. To minimize contamination of nitrate-N in groundwater, it is important to estimate hot spots (>10 mg/L of NO3 -- N, trends and persistence of nitrate-N in groundwater. To analyze the trends and persistence of nitrate-N in groundwater at multiple spatio-temporal scales, we developed and used an entropy-based method along with the Hurst exponent in two different hydrogeologic settings: the Trinity and Ogallala Aquifers in Texas at fine (2 km × 2 km, intermediate (10 km × 10 km and coarse (100 km × 100 km scales. Results show that nitrate-N exhibits long-term persistence at the intermediate and coarse scales. In the Trinity Aquifer, overall mean nitrate-N has declined with a slight increase in normalized marginal entropy (NME over each decade from 1940 to 2008; however, the number of hot spots has increased over time. In the Ogallala Aquifer, overall mean nitrate-N has increased with slight moderation in NME since 1940; however, the number of hot spots has significantly decreased for the same period at all scales.

  9. Thioploca spp: filamentous sulfur bacteria with nitrate vacuoles

    DEFF Research Database (Denmark)

    Jørgensen, BB; Gallardo, VA

    1999-01-01

    communities of large Thioploca species live along the Pacific coast of South America and in other upwelling areas of high organic matter sedimentation with bottom waters poor in oxygen and rich in nitrate. Each cell of these thioplocas harbors a large liquid vacuole which is used as a storage for nitrate...... with a concentration of lip to 506 mM. The nitrate is used as an electron acceptor for sulfide oxidation and the bacteria may grow autotrophically or mixotrophically using acetate or other organic molecules as carbon source. The filaments stretch up into the overlying seawater, from which they take up nitrate...

  10. Anoxic Activated Sludge Monitoring with Combined Nitrate and Titrimetric Measurements

    DEFF Research Database (Denmark)

    Petersen, B.; Gernaey, Krist; Vanrolleghem, P.A.

    2002-01-01

    An experimental procedure for anoxic activated sludge monitoring with combined nitrate and titrimetric measurements is proposed and evaluated successfully with two known carbon sources, (-)acetate and dextrose. For nitrate measurements an ion-selective nitrate electrode is applied to allow...... was with the carbon source in excess, since excess nitrate provoked nitrite build-up thereby complicating the data interpretation. A conceptual model could quantitatively describe the experimental observations and thus link the experimentally measured proton production with the consumption of electron acceptor...... and carbon source during denitrification....

  11. Regioselective nitration of aromatic substrates in zeolite cages

    Indian Academy of Sciences (India)

    T Esakkidurai; M Kumarraja; K Pitchumani

    2003-04-01

    Phenol is nitrated regioselectively by fuming nitric acid inside the cages of faujasite zeolites (dependent on the loading level) and a remarkable orthoselectivity is observed in solid state nitration. Toluene and chlorobenzene also containing ortho-/para-orienting substituents, undergo faster nitration, though the regioselectivity is less significant in zeolite media. The results are explained on the basis of diffusion and binding of phenol inside zeolite, which facilitate regioselectivity (and which is absent in toluene and chlorobenzene). Other advantages of employing zeolites as media for mild and selective nitration are also highlighted.

  12. Endogenously Nitrated Proteins in Mouse Brain: Links To Neurodegenerative Disease

    Energy Technology Data Exchange (ETDEWEB)

    Sacksteder, Colette A.; Qian, Weijun; Knyushko, Tanya V.; Wang, Haixing H.; Chin, Mark H.; Lacan, Goran; Melega, William P.; Camp, David G.; Smith, Richard D.; Smith, Desmond J.; Squier, Thomas C.; Bigelow, Diana J.

    2006-07-04

    Increased nitrotyrosine modification of proteins has been documented in multiple pathologies in a variety of tissue types; emerging evidence suggests its additional role in redox regulation of normal metabolism. In order to identify proteins sensitive to nitrating conditions in vivo, a comprehensive proteomic dataset identifying 7,792 proteins from whole mouse brain, generated by LC/LC-MS/MS analyses, was used to identify nitrated proteins. This analysis resulted in identification of 31 unique nitrotyrosine sites within 29 different proteins. Over half of the nitrated proteins identified have been reported to be involved in Parkinson's disease, Alzheimer's disease, or other neurodegenerative disorders. Similarly, nitrotyrosine immunoblots of whole brain homogenates show that treatment of mice with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), an experimental model of Parkinson's disease, induces increased nitration of the same protein bands observed to be nitrated in brains of untreated animals. Comparing sequences and available high resolution structures around nitrated tyrosines with those of unmodified sites indicates a preference of nitration in vivo for surface accessible tyrosines in loops, characteristics consistent with peroxynitrite-induced tyrosine modification. More striking is the five-fold greater nitration of tyrosines having nearby basic sidechains, suggesting electrostatic attraction of basic groups with the negative charge of peroxynitrite. Together, these results suggest that elevated peroxynitrite generation plays a role in neurodegenerative changes in the brain and provides a predictive tool of functionally important sites of nitration.

  13. Electrochemical Studies of Nitrate-Induced Pitting in Carbon Steel

    Energy Technology Data Exchange (ETDEWEB)

    Zapp, P.E.

    1998-12-07

    The phenomenon of pitting in carbon steel exposed to alkaline solutions of nitrate and chloride was studied with the cyclic potentiodynamic polarization technique. Open-circuit and pitting potentials were measured on specimens of ASTM A537 carbon steel in pH 9.73 salt solutions at 40 degrees Celsius, with and without the inhibiting nitrite ion present. Nitrate is not so aggressive a pitting agent as is chloride. Both nitrate and chloride did induce passive breakdown and pitting in nitrite-free solutions, but the carbon steel retained passivity in solutions with 0.11-M nitrite even at a nitrate concentration of 2.2 M.

  14. NITRATE REDUCTASE ACTIVITY DURING HEAT SHOCK IN WINTER WHEAT

    Directory of Open Access Journals (Sweden)

    Klimenko S.B.

    2006-03-01

    Full Text Available Nitrates are the basic source of nitrogen for the majority of plants. Absorption and transformation of nitrates in plants are determined by external conditions and, first of all, temperature and light intensity. The influence of the temperature increasing till +40 0С on activity of nitrate reductase was studied. It is shown, that the rise of temperature was accompanied by sharp decrease of activity nitrate reductase in leaves of winter wheat, what, apparently, occurred for the account deactivations of enzyme and due to its dissociation.

  15. Calcium binding protein-mediated regulation of voltage-gated calcium channels linked to human diseases

    Institute of Scientific and Technical Information of China (English)

    Nasrin NFJATBAKHSH; Zhong-ping FENG

    2011-01-01

    Calcium ion entry through voltage-gated calcium channels is essential for cellular signalling in a wide variety of cells and multiple physiological processes. Perturbations of voltage-gated calcium channel function can lead to pathophysiological consequences. Calcium binding proteins serve as calcium sensors and regulate the calcium channel properties via feedback mechanisms. This review highlights the current evidences of calcium binding protein-mediated channel regulation in human diseases.

  16. Vascular calcification: Inducers and inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Donghyun, E-mail: dhlee@cau.ac.kr [Department of Biomedical Engineering, Division of Integrative Engineering, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul 156-756 (Korea, Republic of)

    2011-09-15

    Highlights: {center_dot} Types of vascular calcification processes. {center_dot} Inducers of vascular calcification. {center_dot} Inhibitors of vascular calcifications. {center_dot} Clinical utility for vascular calcification therapy. {center_dot} Implications for the development of new tissue engineering strategies. - Abstract: Unlike the traditional beliefs, there are mounting evidences suggesting that ectopic mineral depositions, including vascular calcification are mostly active processes, many times resembling that of the bone mineralization. Numbers of agents are involved in the differentiation of certain subpopulation of smooth muscle cells (SMCs) into the osteoblast-like entity, and the activation and initiation of extracellular matrix ossification process. On the other hand, there are factors as well, that prevent such differentiation and ectopic calcium phosphate formation. In normal physiological environments, activities of such procalcific and anticalcific regulatory factors are in harmony, prohibiting abnormal calcification from occurring. However, in certain pathophysiological conditions, such as atherosclerosis, chronic kidney disease (CKD), and diabetes, such balances are altered, resulting in abnormal ectopic mineral deposition. Understanding the factors that regulate the formation and inhibition of ectopic mineral formation would be beneficial in the development of tissue engineering strategies for prevention and/or treatment of such soft-tissue calcification. Current review focuses on the factors that seem to be clinically relevant and/or could be useful in developing future tissue regeneration strategies. Clinical utilities and implications of such factors are also discussed.

  17. Calcium signals in olfactory neurons.

    Science.gov (United States)

    Tareilus, E; Noé, J; Breer, H

    1995-11-09

    Laser scanning confocal microscopy in combination with the fluorescent calcium indicators Fluo-3 and Fura-Red was employed to estimate the intracellular concentration of free calcium ions in individual olfactory receptor neurons and to monitor temporal and spatial changes in the Ca(2+)-level upon stimulation. The chemosensory cells responded to odorants with a significant increase in the calcium concentration, preferentially in the dendritic knob. Applying various stimulation paradigma, it was found that in a population of isolated cells, subsets of receptor neurons display distinct patterns of responsiveness.

  18. Electrochemical processing of nitrate waste solutions

    Energy Technology Data Exchange (ETDEWEB)

    Genders, D.; Weinberg, N.; Hartsough, D. (Electrosynthesis Co., Inc., Cheektowaga, NY (United States))

    1992-10-07

    The second phase of research performed at The Electrosynthesis Co., Inc. has demonstrated the successful removal of nitrite and nitrate from a synthetic effluent stream via a direct electrochemical reduction at a cathode. It was shown that direct reduction occurs at good current efficiencies in 1,000 hour studies. The membrane separation process is not readily achievable for the removal of nitrites and nitrates due to poor current efficiencies and membrane stability problems. A direct reduction process was studied at various cathode materials in a flow cell using the complete synthetic mix. Lead was found to be the cathode material of choice, displaying good current efficiencies and stability in short and long term tests under conditions of high temperature and high current density. Several anode materials were studied in both undivided and divided cell configurations. A divided cell configuration was preferable because it would prevent re-oxidation of nitrite by the anode. The technical objective of eliminating electrode fouling and solids formation was achieved although anode materials which had demonstrated good stability in short term divided cell tests corroded in 1,000 hour experiments. The cause for corrosion is thought to be F[sup [minus

  19. New infrared spectroscopic database for bromine nitrate

    Science.gov (United States)

    Wagner, Georg; Birk, Manfred

    2016-08-01

    Fourier transform infrared measurements of bromine nitrate have been performed in the spectral region 675-1400 cm-1 at 0.014 cm-1 spectral resolution. Absorption cross sections were derived from 38 spectra covering the temperature range from 203 to 296 K and air pressure range from 0 to 190 mbar. For line-by-line analysis, further spectra were recorded at 0.00094 cm-1 spectral resolution at 223 and 293 K. The sample was synthesized from ClONO2 and Br2. Band strengths of the bands ν3 around 803 cm-1 and ν2 around 1286 cm-1 were determined from three pure BrONO2 measurements at different temperatures and pressures. Number densities in the absorption cell were derived from pressure measurements of the purified sample taking into account small amounts of impurities determined spectroscopically. Resulting band strengths are Sν3 = 2.872(52) × 10-17 cm2 molec-1 cm-1 and Sν2 = 3.63(15) × 10-17 cm2 molec-1 cm-1. Absorption cross sections of all measurements were scaled to these band strengths. Further data reduction was achieved with an interpolation scheme based on two-dimensional polynomials in ln(pressure) and temperature. The database is well-suited for remote-sensing application and should reduce the atmospheric bromine nitrate error budget substantially.

  20. Thermal decomposition of supported lithium nitrate catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Maria Lucia [INTEQUI (CONICET-UNSL), 25 de Mayo 384, V. Mercedes, 5730, San Luis (Argentina); Lick, Ileana Daniela [CINDECA (CONICET-UNLP), Calle 47 No 257, La Plata, 1900, Buenos Aires (Argentina); Ponzi, Marta Isabel [INTEQUI (CONICET-UNSL), 25 de Mayo 384, V. Mercedes, 5730, San Luis (Argentina); Castellon, Enrique Rodriguez; Jimenez-Lopez, Antonio [Departamento de Quimica Inorganica, Cristalografia y Mineralogia. Facultad de Ciencias, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Ponzi, Esther Natalia, E-mail: eponzi@quimica.unlp.edu.ar [CINDECA (CONICET-UNLP), Calle 47 No 257, La Plata, 1900, Buenos Aires (Argentina)

    2010-02-20

    New catalysts for soot combustion were prepared by impregnation of different supports (SiO{sub 2}, ZrO{sub 2} and ZrO{sub 2}.nH{sub 2}O) with a LiNO{sub 3} solution and then characterized by means of FTIR, XPS, TGA and UV-vis spectroscopy, whereby the presence of lithium nitrate in the prepared catalysts was identified and quantified. The soot combustion rate using this series of catalysts (LiNO{sub 3}/support) was compared with the activity of a series of impregnated catalysts prepared using LiOH (Li{sub 2}O/supports). Catalysts prepared using LiNO{sub 3} are found to be more active than those prepared using LiOH. The catalytic performance was also studied with a NO/O{sub 2} mixture in the feed, demonstrating that NO increases the combustion rate of soot, probably as a consequence of lithium oxide forming an 'in situ' nitrate ion.

  1. Does the evidence about health risks associated with nitrate ingestion warrant an increase of the nitrate standard for drinking water?

    Directory of Open Access Journals (Sweden)

    Benjamin Nigel

    2006-09-01

    Full Text Available Abstract Several authors have suggested that it is safe to raise the health standard for nitrate in drinking water, and save money on measures associated with nitrate pollution of drinking water resources. The major argument has been that the epidemiologic evidence for acute and chronic health effects related to drinking water nitrate at concentrations near the health standard is inconclusive. With respect to the chronic effects, the argument was motivated by the absence of evidence for adverse health effects related to ingestion of nitrate from dietary sources. An interdisciplinary discussion of these arguments led to three important observations. First, there have been only a few well-designed epidemiologic studies that evaluated ingestion of nitrate in drinking water and risk of specific cancers or adverse reproductive outcomes among potentially susceptible subgroups likely to have elevated endogenous nitrosation. Positive associations have been observed for some but not all health outcomes evaluated. Second, the epidemiologic studies of cancer do not support an association between ingestion of dietary nitrate (vegetables and an increased risk of cancer, because intake of dietary nitrate is associated with intake of antioxidants and other beneficial phytochemicals. Third, 2–3 % of the population in Western Europe and the US could be exposed to nitrate levels in drinking water exceeding the WHO standard of 50 mg/l nitrate, particularly those living in rural areas. The health losses due to this exposure cannot be estimated. Therefore, we conclude that it is not possible to weigh the costs and benefits from changing the nitrate standard for drinking water and groundwater resources by considering the potential consequences for human health and by considering the potential savings due to reduced costs for nitrate removal and prevention of nitrate pollution.

  2. Calcium-acting drugs modulate expression and development of chronic tolerance to nicotine-induced antinociception in mice.

    Science.gov (United States)

    Damaj, M I

    2005-11-01

    Initial studies in our laboratory suggested that tolerance to nicotine is thought to involve neuronal adaptation not only at the level of the drug-receptor interaction but at postreceptor events such as calcium-dependent second messengers. The present study was undertaken to investigate the hypothesis that L-type calcium channels and calcium-dependent calmodulin protein kinase II are involved in the development and expression of nicotine tolerance. To that end, the effects of modulation of L-type calcium channels (through the use of inhibitors or activators) as well as calcium-dependent calmodulin protein kinase II inactivation were studied in a mouse model of tolerance where mice were infused with nicotine in minipumps (24 mg/kg/day) for 14 days. In addition, the activity of calcium-dependent calmodulin protein kinase II in the lumbar spinal cord region obtained from nicotine-tolerant mice was measured. Our data showed that chronic administration of L-type calcium channel antagonists nimodipine (1 and 5 mg/kg) and verapamil (10 mg/kg) prevented the development of tolerance to nicotine-induced antinociception. In contrast, chronic exposure of BAYK8644 [(+/-)-1,4-dihydro-2,6-dimethyl-5-nitro-4-[2-(trifluoromethyl)-phenyl]-3-pyridine carboxylic acid methyl ester], a calcium channel activator, enhanced nicotine's tolerance. Moreover, a significant increase in both dependent and independent calcium-dependent calmodulin protein kinase II activity was seen in the spinal cord in nicotine-tolerant mice. Finally, spinal administration of 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-tyrosyl]-4-phenylpiperazine (KN-62), a calcium-dependent calmodulin protein kinase II antagonist, reduced the expression of tolerance to nicotine-induced antinociception in mice. In conclusion, our data indicate that calcium-dependent mechanisms such as L-type calcium channels and calcium-dependent calmodulin protein kinase II activation are involved in the expression and development of nicotine

  3. [Clinical efficacy of calcium channel blockers slow the third generation of lercanidipine in the treatment of patients with arterial hypertension and metabolic disorders (review)].

    Science.gov (United States)

    Tabidze, G A; Gezeli, T D; Tsibadze, T A; Dolidze, N M

    2015-02-01

    Arterial hypertension is the most common risk factor in patients with metabolic disorders. In the selection of antihypertensive therapy it is necessary to consider not only the anti-hypertensive and organoprotective effects of drugs and their metabolic effects, which has prognostic value. Calcium antaginists, along. Lercanidipine related to the third generation dihydripyridine calcium antagonist, has been much more selective for the so-called slow calcium channels of vascular smooth muscle cells, which is associated with a good hypertensive, organo and metabolic action. Combination therapy with an ACE inhibitor and a calcium channel blocker is also a justified tactic for the management of patients with high-risk cardiovascular and metabolic disorders. Attention is paid new fixed combinations, including angiotensin converting enzyme inhibitors and calcium antagonists.

  4. A modified procedure for measuring oxygen-18 content of nitrate

    Science.gov (United States)

    Ahmed, M. A.; Aly, A. I. M.; Abdel Monem, N.; Hanafy, M.; Gomaa, H. E.

    2012-11-01

    SummaryMass spectrometric analysis of O-isotopic composition of nitrate has many potential applications in studies of environmental processes. Through this work, rapid, reliable, precise, broadly applicable, catalyst-free, low-priced and less labor intensive procedure for measuring δ18O of nitrate using Isotope Ratio Mass Spectrometer has been developed and implemented. The conditions necessary to effect complete nitrate recovery and complete removal of other oxygen containing anions and dissolved organic carbon (DOC) without scarifying the isotopic signature of nitrate were investigated. The developed procedure consists of two main parts: (1) wet chemistry train for extraction and purification of nitrate from the liquid matrix; (2) off-line pyrolysis of extracted nitrate salt with activated graphite at 550 °C for 30 min. The conditions necessary to effect complete nitrate recovery and complete removal of other oxygen containing compounds were investigated. Dramatic reduction in processing times needed for analysis of δ18O of nitrate at natural abundance level was achieved. Preservation experiments revealed that chloroform (99.8%) is an effective preservative. Isotopic contents of some selected nitrate salts were measured using the modified procedure and some other well established methods at two laboratories in Egypt and Germany. Performance assessment of the whole developed analytical train was made using internationally distributed nitrate isotopes reference materials and real world sample of initial zero-nitrate content. The uncertainty budget was evaluated using the graphical nested hierarchal approach. The obtained results proved the suitability for handling samples of complicated matrices. Reduction of consumables cost by about 80% was achieved.

  5. Calcium signaling mediates antifungal activity of triazole drugs in the Aspergilli.

    Science.gov (United States)

    Liu, Fei-fei; Pu, Li; Zheng, Qing-qing; Zhang, Yuan-wei; Gao, Rong-sui; Xu, Xu-shi; Zhang, Shi-zhu; Lu, Ling

    2015-08-01

    Azoles are widely applied and largely effective as antifungals; however, the increasing prevalence of clinically resistant isolates has yet to be matched by approaches to improve the efficacy of antimicrobial therapy. In this study, using the model fungus Aspergillus nidulans and one of the most common human pathogen Aspergillus fumigatus as research materials, we present the evidence that calcium signaling is involved in the azole-antifungals-induced stress-response reactions. In normal media, antifungal-itraconazole (ITZ) is able to induce the [Ca(2+)]c increased sharply but the addition of calcium chelator-EGTA or BAPTA almost blocks the calcium influx responses, resulted in the dramatically decreasing of [Ca(2+)]c transient. Real-time PCR analysis verified that six-tested Ca(2+)-inducible genes-two calcium channels (cchA/midA), a calmodulin-dependent phosphatase-calcineurin (cnaA), a transcription factor-crzA, and two calcium transporters (pmrA/pmcA)-could be transiently up-regulated by adding ITZ, indicating these components are involved in the azole stress-response reaction. Defect of cnaA or crzA caused more susceptibility to azole antifungals than did single mutants or double deletions of midA and cchA. Notably, EGTA may influence Rh123 accumulation as an azole-mimicking substrate through the process of the drug absorption. In vivo studies of a Galleria mellonella model identified that the calcium chelator works as an adjunct antifungal agent with azoles for invasive aspergillosis. Most importantly, combination of ITZ and EGTA or ITZ with calcium signaling inhibitor-FK506 greatly enhances the ITZ efficacy. Thus, our study provides potential clues that specific inhibitors of calcium signaling could be clinically useful adjuncts to conventional azole antifungals in the Aspergilli.

  6. 21 CFR 184.1187 - Calcium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005.... Calcium alginate is prepared by the neutralization of purified alginic acid with appropriate pH...

  7. Clinical observation of calcium dobesilate in the treatment of chronic renal allograft dysfunction

    Institute of Scientific and Technical Information of China (English)

    Zheng Xue-yang; Han Shu; Zhou Mei-sheng; Fu Shang-xi; Wang Li-ming

    2014-01-01

    Abstract BACKGROUND: Calcium dobesilate (calcium dihydroxy-2, 5-benzenesulfonate) has been widely used to treat chronic venous insufficiency and diabetic retinopathy, especialy many clinical studies showed that calcium dobesilate as vasoprotective compound ameliorates renal lesions in diabetic nephropathy. However, there are few literatures reported calcium dobesilate in the treatment of chronic renal alograft dysfunction after renal transplantation. OBJECTIVE:To observe the efficacy and safety of calcium dobesilate on chronic renal dysfunction after renal transplantation. METHODS:A total of 152 patients with chronic renal alograft dysfunction after renal transplantation were enroled from the Military Institute of Organ Transplantation, Changzheng Hospital, Second Military Medical University of Chinese PLA. They were randomly divided into the treatment group (n=78) and the control group (n=74). Patients in the treatment group received 500 mg of calcium dobesilate three times daily for eight weeks. Al patients were treated with calcineurin inhibitor-based triple immunosuppressive protocols and comprehensive therapies. RESULTS AND CONCLUSION: For patients receiving calcium dobesilate, serum creatinine, blood urea nitrogen and uric acid decreased significantly at two weeks after treatment and maintained a stable level (P 0.05). Administration of calcium dobesilate did not change the general condition of patients with renal insufficiency, nor did it affect blood concentrations of the immunosuppressive agents. Calcium dobesilate may help to delay the progress of graft injury in patients with chronic renal graft dysfunction by conjugating with creatinine, ameliorating the impaired microcirculation and its antioxidant property. The decline in serum creatinine aleviates patients’ anxiety and concern arising from the elevation of creatinine. However, the negative interference with serum creatinine caused by calcium dobesilate should be cautious in order to avoid

  8. Modulation of intracellular calcium levels by calcium lactate affects colon cancer cell motility through calcium-dependent calpain.

    Directory of Open Access Journals (Sweden)

    Pasupathi Sundaramoorthy

    Full Text Available Cancer cell motility is a key phenomenon regulating invasion and metastasis. Focal adhesion kinase (FAK plays a major role in cellular adhesion and metastasis of various cancers. The relationship between dietary supplementation of calcium and colon cancer has been extensively investigated. However, the effect of calcium (Ca2+ supplementation on calpain-FAK-motility is not clearly understood. We sought to identify the mechanism of FAK cleavage through Ca2+ bound lactate (CaLa, its downstream signaling and role in the motility of human colon cancer cells. We found that treating HCT116 and HT-29 cells with CaLa immediately increased the intracellular Ca2+ (iCa2+ levels for a prolonged period of time. Ca2+ influx induced cleavage of FAK into an N-terminal FAK (FERM domain in a dose-dependent manner. Phosphorylated FAK (p-FAK was also cleaved in to its p-N-terminal FAK. CaLa increased colon cancer cells motility. Calpeptin, a calpain inhibitor, reversed the effects of CaLa on FAK and pFAK cleavage in both cancer cell lines. The cleaved FAK translocates into the nucleus and modulates p53 stability through MDM2-associated ubiquitination. CaLa-induced Ca2+ influx increased the motility of colon cancer cells was mediated by calpain activity through FAK and pFAK protein destabilization. In conclusion, these results suggest that careful consideration may be given in deciding dietary Ca2+ supplementation to patient undergoing treatment for metastatic cancer.

  9. Modulation of histamine release from human colon mast cells by protease inhibitors

    Institute of Scientific and Technical Information of China (English)

    Shao-Heng He; Hua Xie

    2004-01-01

    AIM: To investigate the ability of protease inhibitors to modulate histamine release from human colon mast cells.METHODS: Enzymatically dispersed cells from human colon were challenged with anti-IgE or calcium ionophore A23187 in the absence or presence of tryptase and chymase inhibitors, and histamine release was determined.RESULTS: IgE dependent histamine release from colon mast cells was inhibited by up to approximately 37%, 26% and 36.8% by chymase inhibitors Z-Ile-Glu-Pro-Phe-CO2Me (ZIGPFM), N-Tosyl-L-phenylalanyl-chloromethyl ketone (TPCK), and α1-antitrypsin, respectively. Similarly, inhibitors of tryptase leupeptin, N-tosyl-L-lysine chloromethyl ketone (TLCK), lactoferrin and protamine were also able to inhibit anti-IgE induced histamine release by a maximum of some 48%, 37%, 40% and 34%, respectively. Preincubation of these inhibitors with cells for 20 min before challenged with anti-IgE had small effect on the inhibitory actions of these inhibitors on colon mast cells. A specific inhibitor of aminopeptidase amastatin had no effect on anti-IgE induced histamine release. The significant inhibition of calcium ionophore induced histamine release was also observed with the inhibitors of tryptase and chymase examined. Apart from leupeptin and protamine, the inhibitors tested by themselves did not stimulate colon mast cells.CONCLUSION: It was demonstrated that both tryptase and chymase inhibitors could inhibit IgE dependent and calcium ionophore induced histamine release from dispersed colon mast cells in a concentration dependent of manner, which suggest that they are likely to be developed as a novel class of anti-inflammatory drugs to treat chronic of colitis in man.

  10. Modeling pitting corrosion of iron exposed to alkaline solutions containing nitrate and nitrite

    Science.gov (United States)

    Chen, Lifeng

    2001-07-01

    Pitting corrosion could be extremely serious for dilute high-level radioactive waste stored or processed in carbon steel tanks at the Savannah River Site. In these solutions, nitrate is an aggressive ion with respect to pitting of carbon steel while nitrite can be used as an inhibitor. Excessive additions of nitrite increase the risk of generating unstable nitrogen compounds during waste processing, and insufficient additions of nitrite could increase the risk of corrosion-induced failure. Thus there are strong incentives to obtain a fundamental understanding of the role of nitrite in pitting corrosion prevention with these solution chemistries. In this dissertation, both a 1-D and a 2-D model are used to study the pitting mechanism as a function of nitrite/nitrate ratios. The 1-D model used BAND(J) to test a reaction mechanism for the passivation behavior by comparing the predicted Open Circuit Potential (OCP) with OCP data from experiments at different NO2-/NO3- ratio. The model predictions are compared with Cyclic Potentiodynamic Polarization (CPP) experiments. A 2-D model was developed for the propagation of a pit in iron by writing subroutines for finite element software of GAMBIT and FIDAP. Geometrically distributed anodic and cathodic reactions are assumed. The results show three partial explanations describing the inhibition influence of nitrite to iron corrosion: the competing reduction reaction of nitrate to nitrite, the formation of Fe(OH)+, and the function of the porous film. The current distributions and the effect of porosity of the film on pH are also explained. The calculation results also show that rate of pit growth decreases as the pit diameter increases until it reaches a constant value. The profile of the local current density on the pit wall is parabolic for small pits and it changes to a linear distribution for large pits. The model predicts that addition of nitrite will decrease the production of ferrous ions and those can prevent iron from

  11. Ouabain, a steroid hormone that signals with slow calcium oscillations

    OpenAIRE

    2001-01-01

    The plant-derived steroid, digoxin, a specific inhibitor of Na,K-ATPase, has been used for centuries in the treatment of heart disease. Recent studies demonstrate the presence of a digoxin analog, ouabain, in mammalian tissue, but its biological role has not been elucidated. Here, we show in renal epithelial cells that ouabain, in doses causing only partial Na,K-ATPase inhibition, acts as a biological inducer of regular, low-frequency intracellular calcium ([Ca2+]i) oscillations that elicit a...

  12. Interactions in Calcium Oxalate Hydrate/Surfactant Systems.

    Science.gov (United States)

    Sikiric; Filipovic-Vincekovic; Babic-Ivancić Vdović Füredi-Milhofer

    1999-04-15

    Phase transformation of calcium oxalate dihydrate (COD) into the thermodynamically stable monohydrate (COM) in anionic (sodium dodecyl sulfate (SDS)) and cationic (dodecylammonium chloride) surfactant solutions has been studied. Both surfactants inhibit, but do not stop transformation from COD to COM due to their preferential adsorption at different crystal faces. SDS acts as a stronger transformation inhibitor. The general shape of adsorption isotherms of both surfactants at the solid/liquid interface is of two-plateau-type, but differences in the adsorption behavior exist. They originate from different ionic and molecular structures of crystal surfaces and interactions between surfactant headgroups and solid surface. Copyright 1999 Academic Press.

  13. Visualization of Golgia apparatus as an intracellular calcium store by laser scanning confocal microscope

    Institute of Scientific and Technical Information of China (English)

    CUIJIE; YANLI; 等

    1995-01-01

    Using laser scanning confocal microscopy,we have found that the in cells loaded with fluo-3/AM,highest intracellular Ca2+ in the perinuclear region is associated with the Golgi apparatus.The spatiotemporal subcellular distribution of Ca2+ in living human fibroblasts exposing to calcium-free medium in response to agonists has been investigated.PDGF,which releases Ca2+ from intracellular stores by inositol(1,4,5)-trisphosphate pathway ,produced a biphasic transient rise in intracellular calcium.The initial rise was resulted from a direct release of calcium from the golgi apparatus.Calcium could be also released from and reaccumulated into the Golgi apparatus by the stimulation of thapsigargin,an inhibitor of the Ca2+ transport ATPase of intracellular calcium store,Permeablizing the plasma membrane by 10μM digitonin resulted in the calcium release from the Golgi apparatus and depletion of the internal calcium store.These results suggest that the Golgi apparatus plays a role in Ca2+ regulation in signal transduction.

  14. Effect of extracellular calcium on the additive effect of theophylline on the cardiac response to catecholamine

    Directory of Open Access Journals (Sweden)

    Shamkuwar Prashant

    2008-01-01

    Full Text Available At different extracellular calcium concentrations, the positive inotropic effect of isoproterenol and isoproterenol in combination with theophylline, a phosphodiesterase inhibitor have been evaluated in the isolated frog heart and the isolated guinea pig left atria to investigate whether extracellular calcium produces any effect on the additive effect of the theophylline on the cardiac response to catecholamine. Cumulative dose response study of isoproterenol and isoproterenol in presence of theophylline at different extracellular calcium concentration was performed. The study revealed an increase in additive effect of theophylline on the cardiac response to catecholamine with increase in extracellular calcium concentration, but increase in extracellular calcium concentration decreased the myocardial responsiveness to additive effect of theophylline and isoproterenol combination. The mechanism of positive inotropic effect of isoproterenol and in combination with theophylline involves increase in intracellular cAMP by different pathways and extracellular calcium produces positive inotropic effect by initiating the interaction between the contractile proteins actin and myosin. The study revealed that an increase in the concentration of extracellular calcium increased the additive effect of theophylline and isoproterenol combination, but a decrease in the myocardial responsiveness was observed.

  15. Relationship of intracellular calcium and oxygen radicals to Cisplatin-related renal cell injury.

    Science.gov (United States)

    Kawai, Yoshiko; Nakao, Takafumi; Kunimura, Naoshi; Kohda, Yuka; Gemba, Munekazu

    2006-01-01

    We investigated the involvement of reactive oxygen species (ROS) and intracellular calcium in nephrotoxicity related to an antitumor agent, cisplatin. In this study, we employed cultured renal epithelial cells (LLC-PK1). Cisplatin at 500 microM significantly increased the production of ROS 5 h and caused cell injury. This agent significantly increased the intracellular calcium level ([Ca2+]i) in a dose-dependent manner 1 h or more after exposure. DPPD (N,N'-diphenyl-p-phenylenediamine), an antioxidant, inhibited a cisplatin-related increase in active oxygen production and cell injury but did not inhibit an early increase in the [Ca2+]i level. An intracellular calcium-chelating compound BAPTA-AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl) ester) inhibited an increase in ROS production and cell injury induced by cisplatin. Furthermore, BAPTA-AM suppressed the rise of [Ca2+]i level in 1 h after exposure; however, an extracellular calcium chelator EGTA and a calcium antagonist nicardipine did not inhibit the rise in [Ca2+]i level in the early phase. An NADPH oxidase inhibitor inhibited a cisplatin-related increase in ROS production and cell disorder. These results suggest that cisplatin-related calcium release from the site of intracellular calcium storage in the early phase causes oxidative stress in renal tubular epithelial cells. Cisplatin may increase the intracellular production of ROS via NADPH oxidase.

  16. Phosphocitrate inhibits mitochondrial and cytosolic accumulation of calcium in kidney cells in vivo.

    Science.gov (United States)

    Tew, W P; Malis, C D; Howard, J E; Lehninger, A L

    1981-09-01

    Synthetic 3-phosphocitrate, an extremely potent inhibitor of calcium phosphate crystallization as determined in a nonbiological physical-chemical assay, has many similarities to a mitochondrial factor that inhibits crystallization of nondiffracting amorphous calcium phosphate. In order to determine whether phosphocitrate can prevent uptake and crystallization of calcium phosphate in mitochondria in vivo, it was administered intraperitoneally to animals given large daily doses of calcium gluconate or parathyroid hormone, a regimen that causes massive accumulation and crystallization of calcium phosphate in the mitochondria and cytosol of renal tubule cells in vivo. Administration of phosphocitrate greatly reduced the net uptake of Ca2+ by the kidneys and prevented the appearance of apatite-like crystalline structures within the mitochondrial matrix and cytosol of renal tubule cells. Phosphocitrate, which is a poor chelator of Ca2+, did not reduce the hypercalcemia induced by either agent. These in vivo observations therefore indicate that phosphocitrate acts primarily at the cellular level to prevent the extensive accumulation of calcium phosphate in kidney cells by inhibiting the mitochondrial accumulation or crystallization of calcium phosphate.

  17. Heat transfer behavior of molten nitrate salt

    Science.gov (United States)

    Das, Apurba K.; Clark, Michael M.; Teigen, Bard C.; Fiveland, Woodrow A.; Anderson, Mark H.

    2016-05-01

    The usage of molten nitrate salt as heat transfer fluid and thermal storage medium decouples the generation of electricity from the variable nature of the solar resource, allowing CSP plants to avoid curtailment and match production with demand. This however brings some unique challenges for the design of the molten salt central receiver (MSCR). An aspect critical to the use of molten nitrate (60wt%/40wt% - NaNO3/KNO3) salt as heat transfer fluid in the MSCR is to understand its heat transfer behavior. Alstom collaborated with the University of Wisconsin to conduct a series of experiments and experimentally determined the heat transfer coefficients of molten nitrate salt up to high Reynolds number (Re > 2.0E5) and heat flux (q″ > 1000 kW/m2), conditions heretofore not reported in the literature. A cartridge heater instrumented with thermocouples was installed inside a stainless steel pipe to form an annular test section. The test section was installed in the molten salt flow loop at the University of Wisconsin facility, and operated over a range of test conditions to determine heat transfer data that covered the expected operating regime of a practical molten salt receiver. Heat transfer data were compared to widely accepted correlations found in heat transfer literature, including that of Gnielinski. At lower Reynolds number conditions, the results from this work concurred with the molten salt heat transfer data reported in literature and followed the aforementioned correlations. However, in the region of interest for practical receiver design, the correlations did not accurately model the experimentally determined heat transfer data. Two major effects were observed: (i) all other factors remaining constant, the Nusselt numbers gradually plateaued at higher Reynolds number; and (ii) at higher Reynolds number a positive interaction of heat flux on Nusselt number was noted. These effects are definitely not modeled by the existing correlations. In this paper a new

  18. Influence of maleic acid copolymers on calcium orthophosphates crystallization at low temperature

    Science.gov (United States)

    Pelin, Irina M.; Popescu, Irina; Suflet, Dana M.; Aflori, Magdalena; Bulacovschi, Victor

    2013-08-01

    The goal of this study was to investigate the maleic acid copolymers role on calcium orthophosphates crystallization at low temperature. In this respect, two maleic acid copolymers with different structures [poly(sodium maleate-co-vinyl acetate) and poly(sodium maleate-co-methyl methacrylate)] were used. The syntheses of the calcium orthophosphates in the absence and in the presence of the copolymers were performed through the wet chemical method using calcium nitrate, ammonium dihydrogen phosphate and ammonium hydroxide as reactants. The syntheses were monitored in situ by potentiometric and conductometric measurements. To ensure the transformation of less thermodynamically stable calcium orthophosphates into more stable forms, the samples were aged 30 days in mother solutions, at room temperature. The presence of the copolymers in the final products was evidenced by FTIR spectroscopy and thermogravimetric analysis. Scanning and transmission electron microscopy and laser light scattering measurements gave information about the composites morphology and the size of the formed structures. X-ray diffraction evidenced that, as a function of comonomer structure and of copolymer concentration, the products could contain hydroxyapatite with low crystallinity, calcium-deficient or carbonated hydroxyapatite. At high concentration of poly(sodium maleate-co-methyl methacrylate) the transformation of brushite into apatitic structures was inhibited.

  19. Calcium Orthophosphate Cements and Concretes

    Directory of Open Access Journals (Sweden)

    Sergey V. Dorozhkin

    2009-03-01

    Full Text Available In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are a bioactive and biodegradable grafting material in the form of a powder and a liquid. Both phases form after mixing a viscous paste that after being implanted, sets and hardens within the body as either a non-stoichiometric calcium deficient hydroxyapatite (CDHA or brushite, sometimes blended with unreacted particles and other phases. As both CDHA and brushite are remarkably biocompartible and bioresorbable (therefore, in vivo they can be replaced with newly forming bone, calcium orthophosphate cements represent a good correction technique for non-weight-bearing bone fractures or defects and appear to be very promising materials for bone grafting applications. Besides, these cements possess an excellent osteoconductivity, molding capabilities and easy manipulation. Furthermore, reinforced cement formulations are available, which in a certain sense might be described as calcium orthophosphate concretes. The concepts established by calcium orthophosphate cement pioneers in the early 1980s were used as a platform to initiate a new generation of bone substitute materials for commercialization. Since then, advances have been made in the composition, performance and manufacturing; several beneficial formulations have already been introduced as a result. Many other compositions are in experimental stages. In this review, an insight into calcium orthophosphate cements and concretes, as excellent biomaterials suitable for both dental and bone grafting application, has been provided.

  20. Ratiometric analysis of fura red by flow cytometry: a technique for monitoring intracellular calcium flux in primary cell subsets.

    Directory of Open Access Journals (Sweden)

    Emily R Wendt

    Full Text Available Calcium flux is a rapid and sensitive measure of cell activation whose utility could be enhanced with better techniques for data extraction. We describe a technique to monitor calcium flux by flow cytometry, measuring Fura Red calcium dye by ratiometric analysis. This technique has several advantages: 1 using a single calcium dye provides an additional channel for surface marker characterization, 2 allows robust detection of calcium flux by minority cell populations within a heterogeneous population of primary T cells and monocytes 3 can measure total calcium flux and additionally, the proportion of responding cells, 4 can be applied to studying the effects of drug treatment, simultaneously stimulating and monitoring untreated and drug treated cells. Using chemokine receptor activation as an example, we highlight the utility of this assay, demonstrating that only cells expressing a specific chemokine receptor are activated by cognate chemokine ligand. Furthermore, we describe a technique for simultaneously stimulating and monitoring calcium flux in vehicle and drug treated cells, demonstrating the effects of the Gαi inhibitor, pertussis toxin (PTX, on chemokine stimulated calcium flux. The described real time calcium flux assay provides a robust platform for characterizing cell activation within primary cells, and offers a more accurate technique for studying the effect of drug treatment on receptor activation in a heterogeneous population of primary cells.

  1. Mefloquine-Induced Disruption of Calcium Homeostasis in Mammalian Cells Is Similar to That Induced by Ionomycin▿

    Science.gov (United States)

    Caridha, D.; Yourick, D.; Cabezas, M.; Wolf, L.; Hudson, T. H.; Dow, G. S.

    2008-01-01

    In previous studies, we have shown that mefloquine disrupts calcium homeostasis in neurons by depletion of endoplasmic reticulum (ER) stores, followed by an influx of external calcium across the plasma membrane. In this study, we explore two hypotheses concerning the mechanism(s) of action of mefloquine. First, we investigated the possibility that mefloquine activates non-N-methyl-d-aspartic acid receptors and the inositol phosphate 3 (IP3) signaling cascade leading to ER calcium release. Second, we compared the disruptive effects of mefloquine on calcium homeostasis to those of ionomycin in neuronal and nonneuronal cells. Ionomycin is known to discharge the ER calcium store (through an undefined mechanism), which induces capacitative calcium entry (CCE). In radioligand binding assays, mefloquine showed no affinity for the known binding sites of several glutamate receptor subtypes. The pattern of neuroprotection induced by a panel of glutamate receptor antagonists was dissimilar to that of mefloquine. Both mefloquine and ionomycin exhibited dose-related and qualitatively similar disruptions of calcium homeostasis in both neurons and macrophages. The influx of external calcium was blocked by the inhibitors of CCE in a dose-related fashion. Both mefloquine and ionomycin upregulated the IP3 pathway in a manner that we interpret to be secondary to CCE. Collectively, these data suggest that mefloquine does not activate glutamate receptors and that it disrupts calcium homeostasis in mammalian cells in a manner similar to that of ionomycin. PMID:17999964

  2. Removal of Nitrate From Aqueous Solution Using Rice Chaff

    Directory of Open Access Journals (Sweden)

    Dehghani

    2015-09-01

    Full Text Available Background Nitrate is largely dissolved in the surface and ground water, due to its high solubility. Continual uptake of nitrite through drinking water can lead to problems and diseases (such as blue baby for humans, especially children. Objectives The aim of this study was to develop a new and inexpensive method for the removal of nitrate from water. In this regard, the possibility of using chaff for removal of nitrate from aqueous solutions was studied and the optimum operating conditions of nitrate removal was determined. Materials and Methods This is a cross-sectional study conducted in laboratory scale. The UV spectrophotometer at a wavelength of maximum absorbance (220 nm was used to determine the nitrate concentration. The effect of pH, amount of chaff, temperature, and contact time were investigated. Results The result of this study revealed that chaff as an absorbent could remove nitrate from solutions, and the efficiency of adsorption increased as contact time increased from 5 to 30 minutes, amount of chaff increased from 1 to 3 g, temperature increased in a range of 300 - 400°C and the amount of pH decreased from 10 to 3. The maximum adsorption rate was around pH 3 (53.14%. Conclusions It was shown that the removal efficiency of nitrate was directly proportional to the amount of chaff, temperature, and contact time but inversely to the pH. This study showed that nitrate removal by chaff is a promising technique.

  3. Iron-mediated effects on nitrate reductase in marine phytoplankton

    NARCIS (Netherlands)

    Timmermans, K.R.; Stolte, W.; Baar, H.J.W. de

    1994-01-01

    The potential activity of nitrate reductase was determined in uni-algal cultures in the laboratory and in natural marine phytoplankton assemblages. In the laboratory bioassays, distinct differences in nitrate reductase activity were observed in iron replete versus depleted cultures for Emiliania hux

  4. Robust options to remove nitrate and phosphate from tile drainage

    NARCIS (Netherlands)

    Jansen, Stefan; Gerritse, Jan; Stuurman, Roelof; Chardon, W.J.; Talens, René

    2016-01-01

    Diffuse emission from agricultural land is a major, persistent source of nitrogen and phosphorus in surface waters. In this contribution, we present field experiments of a series of robust options to remove nitrate and phosphorus at
    field drainage level. Nitrate removal was enhanced by stimulati

  5. Nitrate and nitrite in biology, nutrition and therapeutics

    NARCIS (Netherlands)

    Lundberg, J.O.; van Faassen, E.E.H.; Gladwin, M.T.; Ahluwalia, A.; Benjamin, N.

    2009-01-01

    Inorganic nitrate and nitrite from endogenous or dietary sources are metabolized in vivo to nitric oxide (NO) and other bioactive nitrogen oxides. The nitrate-nitrite-NO pathway is emerging as an important mediator of blood flow regulation, cell signaling, energetics and tissue responses to hypoxia.

  6. Spatial assessment of animal manure spreading and groundwater nitrate pollution

    Directory of Open Access Journals (Sweden)

    Roberta Infascelli

    2009-11-01

    Full Text Available Nitrate concentration in groundwater has frequently been linked to non-point pollution. At the same time the existence of intensive agriculture and extremely intensive livestock activity increases the potential for nitrate pollution in shallow groundwater. Nitrate used in agriculture could cause adverse effects on human and animal health. In order to evaluate the groundwater nitrate pollution, and how it might evolve in time, it is essential to develop control systems and to improve policies and incentives aimed at controlling the amount of nitrate entering downstream water systems. The province of Caserta in southern Italy is characterized by high levels of animal manure loading. A comparison between manure nitrogen production and nitrate concentration in groundwater was carried out in this area, using geostatistical tools and spatial statistics. The results show a discrepancy between modelling of nitrate leaching and monitoring of the groundwater and, moreover, no spatial correlation between nitrogen production in livestock farms and nitrate concentration in groundwater, suggesting that producers are not following the regulatory procedures for the agronomic use of manure. The methodology developed in this paper could be applied also in other regions in which European Union fertilization plans are not adequately followed.

  7. Nitrate leaching and pesticide use in energy crops

    DEFF Research Database (Denmark)

    Jørgensen, Uffe

    2006-01-01

    Nitrate leaching measured below willow and miscanthus is very low from the established crops. Pesticide use in energy crops is low as well.......Nitrate leaching measured below willow and miscanthus is very low from the established crops. Pesticide use in energy crops is low as well....

  8. Nitrate Water Activities, Science Study Aid No. 4.

    Science.gov (United States)

    Agricultural Research Service (USDA), Washington, DC.

    Intended to supplement a regular program, this pamphlet provides background information, related activities, and suggestions for other activities on the subject of nitrate as a water pollutant. Two activities related to plant nutrient pollution, nitrate filtration and measuring mitrate used by plants, are explained in detail, outlining objectives,…

  9. More answers to the still unresolved question of nitrate tolerance.

    Science.gov (United States)

    Münzel, Thomas; Daiber, Andreas; Gori, Tommaso

    2013-09-01

    Organic nitrates are traditionally felt to be a safe adjuvant in the chronic therapy of patients with coronary artery disease. Despite their long use, progress in the understanding of the pharmacology and mechanism of action of these drugs has been achieved only in the last two decades, with the identification of the role of oxidative stress in the pathophysiology of nitrate tolerance, with, the discovery of the ancillary effects of nitrates, and with the demonstration that nitrate therapy has important chronic side effects that might modify patients' prognosis. These advances are however mostly confined to the molecular level or to studies in healthy volunteers, and the true impact of organic nitrates on clinical outcome remains unknown. Complicating this issue, evidence supports the existence of important differences among the different drugs belonging to the group, and there are reasons to believe that the nitrates should not be treated as a homogeneous class. As well, the understanding of the effects of alternative nitric oxide (NO) donors is currently being developed, and future studies will need to test whether the properties of these new medications may compensate and prevent the abnormalities imposed by chronic nitrate therapy. Intermittent therapy with nitroglycerin and isosorbide mononitrate is now established in clinical practice, but they should neither be considered a definitive solution to the problem of nitrate tolerance. Both these strategies are not deprived of complications, and should currently be seen as a compromise rather than a way fully to exploit the benefits of NO donor therapy.

  10. [Accumulation of nitrates in carrot root--agronomical consequences].

    Science.gov (United States)

    Blanc, D; Otto, C; Mars, S

    1980-01-01

    This paper deals with the effects of various parameters involved in plant nitrogen metabolism, on the nitrate content in carrot roots. Level of mineral nitrogen supply, activity of leaves and light intensity have been taken into account in factorial experiments. Results are discussed with a view to the improvement of the quality of root production with respect to their nitrate content.

  11. Evaluation of nitrate and nitrite destruction/separation technologies

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.T.

    1997-08-29

    This report describes and evaluates four types of nitrate and nitrite destruction and separation technologies that could be used to treat the aqueous, alkaline, nitrate-bearing mixed waste that is generated by the In-Tank Precipitation (ITP) process at the Savannah River Site (SRS). The technologies considered in this report include thermal, hydrothermal, chemical, and electrochemical technologies.

  12. Is nitrate an endocrine active compound in fish?

    DEFF Research Database (Denmark)

    Mose, M. P.; Kinnberg, Karin Lund; Bjerregaard, Poul;

    concentrations around or below the limits for drinking water). Nitrate concentrations in streams may be elevated due to releases from agricultural practices. The effects of nitrate and nitrite on endocrine relevant endpoints were investigated in zebrafish (Danio rerio) and brown trout (Salmo trutta). Zebrafish...

  13. Distribution and Sources of Nitrate-Nitrogen in Kansas Groundwater

    Directory of Open Access Journals (Sweden)

    Margaret A. Townsend

    2001-01-01

    Full Text Available Kansas is primarily an agricultural state. Irrigation water and fertilizer use data show long- term increasing trends. Similarly, nitrate-N concentrations in groundwater show long-term increases and exceed the drinking-water standard of 10 mg/l in many areas. A statistical analysis of nitrate-N data collected for local and regional studies in Kansas from 1990 to 1998 (747 samples found significant relationships between nitrate-N concentration with depth, age, and geographic location of wells. Sources of nitrate-N have been identified for 297 water samples by using nitrogen stable isotopes. Of these samples, 48% showed fertilizer sources (+2 to +8 and 34% showed either animal waste sources (+10 to +15 with nitrate-N greater than 10 mg/l or indication that enrichment processes had occurred (+10 or above with variable nitrate-N or both. Ultimate sources for nitrate include nonpoint sources associated with past farming and fertilization practices, and point sources such as animal feed lots, septic systems, and commercial fertilizer storage units. Detection of nitrate from various sources in aquifers of different depths in geographically varied areas of the state indicates that nonpoint and point sources currently impact and will continue to impact groundwater under current land uses.

  14. Factors affecting calcium balance in Chinese adolescents.

    Science.gov (United States)

    Yin, Jing; Zhang, Qian; Liu, Ailing; Du, Weijing; Wang, Xiaoyan; Hu, Xiaoqi; Ma, Guansheng

    2010-01-01

    Chinese dietary reference intakes (DRIs) for calcium were developed mainly from studies conducted amongst Caucasians, yet a recent review showed that reference calcium intakes for Asians are likely to be different from those of Caucasians (Lee and Jiang, 2008). In order to develop calcium DRIs for Chinese adolescents, it is necessary to explore the characteristics and potential influencing factors of calcium metabolic balance in Chinese adolescents. A total of 80 students (15.1+/-0.8 years) were recruited stratified by gender from a 1-year calcium supplementation study. Subjects were randomly designed to four groups and supplemented with calcium carbonate tablets providing elemental calcium at 63, 354, 660, and 966 mg/day, respectively. Subjects consumed food from a 3-day cycle menu prepared by staff for 10 days. Elemental calcium in samples of foods, feces, and urine was determined in duplicates by inductively coupled plasma atomic emission spectrometry. The total calcium intake ranged from 352 to 1323 mg/day. The calcium apparent absorption efficiency and retention in boys were significantly higher than that in girls (68.7% vs. 46.4%, 480 mg/day vs. 204 mg/day, PCalcium retention increased with calcium intakes, but did not reach a plateau. Calcium absorption efficiency in boys increased with calcium intake up to 665 mg/day, and decreased after that. In girls, calcium absorption efficiency decreased with calcium intake. Calcium absorption efficiency increased within 1 year after first spermatorrhea in boys, but decreased with pubertal development in girls. Sex, calcium intake, age, and pubertal development were the most important determinants of calcium absorption (R(2)=0.508, Pcalcium intake, age, and pubertal development are important factors for calcium retention and absorption during growth, which should be considered for the development of calcium DRIs for Chinese adolescents.

  15. Functional, genetic and bioinformatic characterization of a calcium/calmodulin kinase gene in Sporothrix schenckii

    Directory of Open Access Journals (Sweden)

    Rodriguez-del Valle Nuri

    2007-11-01

    Full Text Available Abstract Background Sporothrix schenckii is a pathogenic, dimorphic fungus, the etiological agent of sporotrichosis, a subcutaneous lymphatic mycosis. Dimorphism in S. schenckii responds to second messengers such as cAMP and calcium, suggesting the possible involvement of a calcium/calmodulin kinase in its regulation. In this study we describe a novel calcium/calmodulin-dependent protein kinase gene in S. schenckii, sscmk1, and the effects of inhibitors of calmodulin and calcium/calmodulin kinases on the yeast to mycelium transition and the yeast cell cycle. Results Using the PCR homology approach a new member of the calcium/calmodulin kinase family, SSCMK1, was identified in this fungus. The cDNA sequence of sscmk1 revealed an open reading frame of 1,221 nucleotides encoding a 407 amino acid protein with a predicted molecular weight of 45.6 kDa. The genomic sequence of sscmk1 revealed the same ORF interrupted by five introns. Bioinformatic analyses of SSCMK1 showed that this protein had the distinctive features that characterize a calcium/calmodulin protein kinase: a serine/threonine protein kinase domain and a calmodulin-binding domain. When compared to homologues from seven species of filamentous fungi, SSCMK1 showed substantial similarities, except for a large and highly variable region that encompasses positions 330 – 380 of the multiple sequence alignment. Inhibition studies using calmodulin inhibitor W-7, and calcium/calmodulin kinase inhibitors, KN-62 and lavendustin C, were found to inhibit budding by cells induced to re-enter the yeast cell cycle and to favor the yeast to mycelium transition. Conclusion This study constitutes the first evidence of the presence of a calcium/calmodulin kinase-encoding gene in S. schenckii and its possible involvement as an effector of dimorphism in this fungus. These results suggest that a calcium/calmodulin dependent signaling pathway could be involved in the regulation of dimorphism in this fungus

  16. Influences of nitrification inhibitor 3,4-dimethyl pyrazole phosphate on nitrogen and soil salt-ion leaching

    Institute of Scientific and Technical Information of China (English)

    YU Qiaogang; YE Xuezhu; CHEN Yingxu; ZHANG Zhijian; TIAN Guangming

    2008-01-01

    An undisturbed heavy clay soil column experiment was conducted to examine the influence of the new nitrification inhibitor,3,4-dimethylpyrazole phosphate (DMPP),on nitrogen and soil salt-ion leaching.Regular urea was selected as the nitrogen source in the soil.The results showed that the cumulative leaching losses of soil nitrate-N under the treatment of urea with DMPP were from 57.5% to 63.3% lower than those of the treatment of urea without DMPP.The use of nitrification inhibitors as nitrate leaching retardants may be a proposal in regulations to prevent groundwater contaminant.However,there were no great difference between urea and urea with DMPP treatments on ammonium-N leaching.Moreover,the soil salt-ion leaching losses of Ca2+,Mg2+,K+,and Na+ were reduced from 26.6% to 28.8%,21.3% to 27.8%,33.3% to 35.5%,and 21.7% to 32.1%,respectively.So,the leaching losses of soil salt-ion were declined for nitrification inhibitor DMPP addition,being beneficial to shallow groundwater protection and growth of crop.These results indicated the possibility of ammonium or ammonium producing compounds using nitrification inhibitor DMPP to control the nitrate and nutrient cation leaching losses,minimizing the risk of nitrate pollution in shallow groundwater.

  17. Influences of nitrification inhibitor 3,4-dimethyl pyrazole phosphate on nitrogen and soil salt-ion leaching.

    Science.gov (United States)

    Yu, Qiaogang; Ye, Xuezhu; Chen, Yingxu; Zhang, Zhijian; Tian, Guangming

    2008-01-01

    An undisturbed heavy clay soil column experiment was conducted to examine the influence of the new nitrification inhibitor, 3,4-dimethylpyrazole phosphate (DMPP), on nitrogen and soil salt-ion leaching. Regular urea was selected as the nitrogen source in the soil. The results showed that the cumulative leaching losses of soil nitrate-N under the treatment of urea with DMPP were from 57.5% to 63.3% lower than those of the treatment of urea without DMPP. The use of nitrification inhibitors as nitrate leaching retardants may be a proposal in regulations to prevent groundwater contaminant. However, there were no great difference between urea and urea with DMPP treatments on ammonium-N leaching. Moreover, the soil salt-ion leaching losses of Ca2+, Mg2+, K+, and Na+ were reduced from 26.6% to 28.8%, 21.3% to 27.8%, 33.3% to 35.5%, and 21.7% to 32.1%, respectively. So, the leaching losses of soil salt-ion were declined for nitrification inhibitor DMPP addition, being beneficial to shallow groundwater protection and growth of crop. These results indicated the possibility of ammonium or ammonium producing compounds using nitrification inhibitor DMPP to control the nitrate and nutrient cation leaching losses, minimizing the risk of nitrate pollution in shallow groundwater.

  18. Calcium paradox induces apoptosis in the isolated perfused Rana ridibunda heart: involvement of p38-MAPK and calpain.

    Science.gov (United States)

    Aggeli, Ioanna-Katerina; Zacharias, Triantafyllos; Papapavlou, Georgia; Gaitanaki, Catherine; Beis, Isidoros

    2013-12-01

    "Calcium paradox" as a term describes the deleterious effects conferred to a heart perfused with a calcium-free solution followed by repletion, including loss of mechanical activity and sarcomere disruption. Given that the signaling mechanisms triggered by calcium paradox remain elusive, in the present study, we tried to investigate them in the isolated perfused heart from Rana ridibunda. Calcium paradox was found to markedly activate members of the MAPKs (p43-ERK, JNKs, p38-MAPK). In addition to lactate dehydrogenase (LDH) release in the perfusate (indicative of necrosis), we also confirmed the occurrence of apoptosis by using the TUNEL assay and identifying poly(ADP-ribose) polymerase (PARP) fragmentation and upregulated Bax expression. Furthermore, using MDL28170 (a selective calpain inhibitor), a role for this protease was revealed. In addition, various divalent cations were shown to exert a protective effect against the calcium paradox. Interestingly, SB203580, a p38-MAPK inhibitor, alleviated calcium-paradox-conferred apoptosis. This result indicates that p38-MAPK plays a pro-apoptotic role, contributing to the resulting myocardial dysfunction and cell death. To our knowledge, this is the first time that the calcium paradox has been shown to induce apoptosis in amphibians, with p38-MAPK and calpain playing significant roles.

  19. Thermal Decomposition of Nitrated Tributyl Phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Paddleford, D.F. [Westinghouse Savannah River Company, Aiken, SC (United States); Hou, Y.; Barefield, E.K.; Tedder, D.W.; Abdel-Khalik, S.I. [Georgia Institute of Technology, GA (United States)

    1995-01-01

    Contact between tributyl phosphate and aqueous solutions of nitric acid and/or heavy metal nitrate salts at elevated temperatures can lead to exothermic reactions of explosive violence. Even though such operations have been routinely performed safely for decades as an intrinsic part of the Purex separation processes, several so-called ``red oil`` explosions are known to have occurred in the United States, Canada, and the former Soviet Union. The most recent red oil explosion occurred at the Tomsk-7 separations facility in Siberia, in April 1993. That explosion destroyed part of the unreinforced masonry walls of the canyon-type building in which the process was housed, and allowed the release of a significant quantity of radioactive material.

  20. Removal of gadolinium nitrate from heavy water

    Energy Technology Data Exchange (ETDEWEB)

    Wilde, E.W.

    2000-03-22

    Work was conducted to develop a cost-effective process to purify 181 55-gallon drums containing spent heavy water moderator (D2O) contaminated with high concentrations of gadolinium nitrate, a chemical used as a neutron poison during former nuclear reactor operations at the Savannah River Site (SRS). These drums also contain low level radioactive contamination, including tritium, which complicates treatment options. Presently, the drums of degraded moderator are being stored on site. It was suggested that a process utilizing biological mechanisms could potentially lower the total cost of heavy water purification by allowing the use of smaller equipment with less product loss and a reduction in the quantity of secondary waste materials produced by the current baseline process (ion exchange).

  1. Hydrogels made from chitosan and silver nitrate.

    Science.gov (United States)

    Kozicki, Marek; Kołodziejczyk, Marek; Szynkowska, Małgorzata; Pawlaczyk, Aleksandra; Leśniewska, Ewa; Matusiak, Aleksandra; Adamus, Agnieszka; Karolczak, Aleksandra

    2016-04-20

    This work describes a gelation of chitosan solution with silver nitrate. Above the critical concentration of chitosan (c*), continuous hydrogels of chitosan-silver can be formed. At lower concentrations, the formation of nano- and micro-hydrogels is discussed. The sol-gel analysis was performed to characterise the hydrogels' swelling properties. Moreover, the following were employed: (i) mechanical testing of hydrogels, (ii) inductively coupled plasma-optical emission spectroscopy (ICP-OES) for the measurement of silver concentration, (iii) scanning electron microscopy (SEM) to examine the morphology of products obtained, and (iv) dynamic light scattering (DLS) and UV-vis spectrophotometry to examine products formed at low concentration of chitosan (chydrogels were used for modification of cotton fabric in order to give it antimicrobial properties. The products obtained acted against Escherichia coli and Bacillus subtilis apart from the chitosan used that showed no such activity.

  2. Transcriptional networks in the nitrate response of Arabidopsis thaliana.

    Science.gov (United States)

    Vidal, Elena A; Álvarez, José M; Moyano, Tomás C; Gutiérrez, Rodrigo A

    2015-10-01

    Nitrogen is an essential macronutrient for plants and its availability is a key determinant of plant growth and development and crop yield. Besides their nutritional role, N nutrients and metabolites are signals that activate signaling pathways that modulate many plant processes. Because the most abundant inorganic N source for plants in agronomic soils is nitrate, much of the work to understand plant N-signaling has focused on this nutrient. Over the last years, several studies defined a comprehensive catalog of nitrate-responsive genes, involved in nitrate transport, metabolism and a variety of other processes. Despite significant progress in recent years, primarily using Arabidopsis thaliana as a model system, the molecular mechanisms by which nitrate elicits changes in transcript abundance are still not fully understood. Here we highlight recent advancements in identifying key transcription factors and transcriptional mechanisms that orchestrate the gene expression response to changes in nitrate availability in A. thaliana.

  3. Photooxidation of cellulose nitrate: new insights into degradation mechanisms.

    Science.gov (United States)

    Berthumeyrie, Sebastien; Collin, Steeve; Bussiere, Pierre-Olivier; Therias, Sandrine

    2014-05-15

    Cellulose nitrate (or nitrocellulose) has received considerable interest due to its uses in various applications, such as paints, photographic films and propellants. However, it is considered as one of the primary pollutants in the energetic material industries because it can be degraded to form polluting chemical species. In this work, the UV light degradation of cellulose nitrate films was studied under conditions of artificially accelerated photooxidation. To eliminate the reactivity of nitro groups, the degradation of ethylcellulose was also investigated. Infrared spectroscopy analyses of the chemical modifications caused by the photooxidation of cellulose nitrate films and the resulting formation of volatile products revealed the occurrence of de-nitration and the formation of oxidation photoproducts exhibiting lactone and anhydride functions. The impact of these chemical modifications on the mechanical and thermal properties of cellulose nitrate films includes embrittlement and lower temperatures of ignition when used as a propellant.

  4. ARRAYS OF BOTTLES OF PLUTONIUM NITRATE SOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Margaret A. Marshall

    2012-09-01

    In October and November of 1981 thirteen approaches-to-critical were performed on a remote split table machine (RSTM) in the Critical Mass Laboratory of Pacific Northwest Laboratory (PNL) in Richland, Washington using planar arrays of polyethylene bottles filled with plutonium (Pu) nitrate solution. Arrays of up to sixteen bottles were used to measure the critical number of bottles and critical array spacing with a tight fitting Plexiglas® reflector on all sides of the arrays except the top. Some experiments used Plexiglas shells fitted around each bottles to determine the effect of moderation on criticality. Each bottle contained approximately 2.4 L of Pu(NO3)4 solution with a Pu content of 105 g Pu/L and a free acid molarity H+ of 5.1. The plutonium was of low 240Pu (2.9 wt.%) content. These experiments were sponsored by Rockwell Hanford Operations because of the lack of experimental data on the criticality of arrays of bottles of Pu solution such as might be found in storage and handling at the Purex Facility at Hanford. The results of these experiments were used “to provide benchmark data to validate calculational codes used in criticality safety assessments of [the] plant configurations” (Ref. 1). Data for this evaluation were collected from the published report (Ref. 1), the approach to critical logbook, the experimenter’s logbook, and communication with the primary experimenter, B. Michael Durst. Of the 13 experiments preformed 10 were evaluated. One of the experiments was not evaluated because it had been thrown out by the experimenter, one was not evaluated because it was a repeat of another experiment and the third was not evaluated because it reported the critical number of bottles as being greater than 25. Seven of the thirteen evaluated experiments were determined to be acceptable benchmark experiments. A similar experiment using uranyl nitrate was benchmarked as U233-SOL-THERM-014.

  5. 76 FR 78150 - Ophthalmic and Topical Dosage Form New Animal Drugs; Hydrocortisone Aceponate, Miconazole Nitrate...

    Science.gov (United States)

    2011-12-16

    ... Animal Drugs; Hydrocortisone Aceponate, Miconazole Nitrate, and Gentamicin Sulfate Otic Suspension AGENCY... hydrocortisone aceponate, miconazole nitrate, and gentamicin sulfate suspension for the treatment of otitis... of EASOTIC (hydrocortisone aceponate, miconazole nitrate, gentamicin sulfate) Suspension for...

  6. Green and controllable metal-free nitrification and nitration of arylboronic acids

    Institute of Scientific and Technical Information of China (English)

    Shuai Wang; Chun Chun Shu; Tao Wang; Jian Yu; Guo Bing Yan

    2012-01-01

    A novel and green nitrating reagent has been developed for the nitrification and nitration of arylboronic acids,which can be controlled by the reaction conditions.The process provides an attractive alternative to the traditional nitration protocols.

  7. Water rotational jump driven large amplitude molecular motions of nitrate ions in aqueous potassium nitrate solution

    CERN Document Server

    Banerjee, Puja; Bagchi, Biman

    2016-01-01

    Molecular dynamics simulations of aqueous potassium nitrate solution reveal a highly complex rotational dynamics of nitrate ions where, superimposed on the expected continuous Brownian motion, are large amplitude angular jumps that are coupled to and at least partly driven by similar large amplitude jump motions in water molecules which are associated with change in the hydrogen bonded water molecule. These jumps contribute significantly to rotational and translational motions of these ions. We explore the detailed mechanism of these correlated (or, coupled) jumps and introduce a new time correlation function to decompose the coupled orientational- jump dynamics of solvent and solute in the aqueous electrolytic solution. Time correlation function provides for the unequivocal determination of the time constant involved in orientational dynamics originating from making and breaking of hydrogen bonds. We discover two distinct mechanisms-both are coupled to density fluctuation but are of different types.

  8. Nitrate removal by nitrate-dependent Fe(II) oxidation in an upflow denitrifying biofilm reactor.

    Science.gov (United States)

    Zhou, Jun; Wang, Hongyu; Yang, Kai; Sun, Yuchong; Tian, Jun

    2015-01-01

    A continuous upflow biofilm reactor packed with ceramsite was constructed for nitrate removal under an anaerobic atmosphere without an organic carbon source. Denitrifying bacteria, Pseudomonas sp. W1, Pseudomonas sp. W2 and Microbacterium sp. W5, were added to the bioreactor as inocula. Nitrate concentration, nitrite accumulation and nitrogen removal efficiency in the effluent were investigated under various conditions set by several parameters including pH, hydraulic retention time (HRT), ratios of carbon to nitrogen (C/N) and temperature. The results illustrated that the maximum removal efficiency of nitrogen was 85.39%, under optimum reaction parameters, approximately pH 6.5-7, HRT = 48 hours and C/N = 13.1:1 at temperature of 30 °C, which were determined by experiment.

  9. Mitochondrial calcium uptake.

    Science.gov (United States)

    Williams, George S B; Boyman, Liron; Chikando, Aristide C; Khairallah, Ramzi J; Lederer, W J

    2013-06-25

    Calcium (Ca(2+)) uptake into the mitochondrial matrix is critically important to cellular function. As a regulator of matrix Ca(2+) levels, this flux influences energy production and can initiate cell death. If large, this flux could potentially alter intracellular Ca(2+) ([Ca(2+)]i) signals. Despite years of study, fundamental disagreements on the extent and speed of mitochondrial Ca(2+) uptake still exist. Here, we review and quantitatively analyze mitochondrial Ca(2+) uptake fluxes from different tissues and interpret the results with respect to the recently proposed mitochondrial Ca(2+) uniporter (MCU) candidate. This quantitative analysis yields four clear results: (i) under physiological conditions, Ca(2+) influx into the mitochondria via the MCU is small relative to other cytosolic Ca(2+) extrusion pathways; (ii) single MCU conductance is ∼6-7 pS (105 mM [Ca(2+)]), and MCU flux appears to be modulated by [Ca(2+)]i, suggesting Ca(2+) regulation of MCU open probability (P(O)); (iii) in the heart, two features are clear: the number of MCU channels per mitochondrion can be calculated, and MCU probability is low under normal conditions; and (iv) in skeletal muscle and liver cells, uptake per mitochondrion varies in magnitude but total uptake per cell still appears to be modest. Based on our analysis of available quantitative data, we conclude that although Ca(2+) critically regulates mitochondrial function, the mitochondria do not act as a significant dynamic buffer of cytosolic Ca(2+) under physiological conditions. Nevertheless, with prolonged (superphysiological) elevations of [Ca(2+)]i, mitochondrial Ca(2+) uptake can increase 10- to 1,000-fold and begin to shape [Ca(2+)]i dynamics.

  10. REMOVAL OF ADDED NITRATE IN COTTON BURR COMPOST, MULCH COMPOST, AND PEAT: MECHANISMS AND POTENTIAL USE FOR GROUNDWATER NITRATE REMEDIATION

    Science.gov (United States)

    We conducted batch tests on the nature and kinetics of removal of added nitrate in cotton burr compost, mulch compost, and sphagnum peat that may be potentially used in a permeable reactive barrier (PRB) for groundwater nitrate remediation. A rigorous steam autoclaving protocol (...

  11. Dopaminergic regulation of dendritic calcium: fast multisite calcium imaging.

    Science.gov (United States)

    Zhou, Wen-Liang; Oikonomou, Katerina D; Short, Shaina M; Antic, Srdjan D

    2013-01-01

    Optimal dopamine tone is required for the normal cortical function; however it is still unclear how cortical-dopamine-release affects information processing in individual cortical neurons. Thousands of glutamatergic inputs impinge onto elaborate dendritic trees of neocortical pyramidal neurons. In the process of ensuing synaptic integration (information processing), a variety of calcium transients are generated in remote dendritic compartments. In order to understand the cellular mechanisms of dopaminergic modulation it is important to know whether and how dopaminergic signals affect dendritic calcium transients. In this chapter, we describe a relatively inexpensive method for monitoring dendritic calcium fluctuations at multiple loci across the pyramidal dendritic tree, at the same moment of time (simultaneously). The experiments have been designed to measure the amplitude, time course and spatial extent of action potential-associated dendritic calcium transients before and after application of dopaminergic drugs. In the examples provided here the dendritic calcium transients were evoked by triggering the somatic action potentials (backpropagation-evoked), and puffs of exogenous dopamine were applied locally onto selected dendritic branches.

  12. Formation of calcium complexes by borogluconate in vitro and during calcium borogluconate infusion in sheep.

    Science.gov (United States)

    Farningham, D A

    1985-07-01

    The effect of borogluconate on plasma calcium fractions was studied in vitro and in vivo in sheep. In vitro calcium chloride was more effective in raising ionised plasma calcium than calcium borogluconate. Sodium borate or gluconate added to blood caused only small decreases in blood ionised calcium. However, together, a synergistic reduction in ionised calcium was observed. Following calcium borogluconate infusions into sheep, total plasma calcium rose primarily because of an increase in the unionised ultrafiltrable fraction. Other changes observed following the infusion were hypercalciuria, decreased glomerular filtration rate and acidosis. Sodium borogluconate administered subcutaneously lowered total plasma calcium. This probably resulted from enhanced calcium excretion. It is suggested that since the anionic component of calcium solutions alters the availability and retention of calcium, it is likely to affect clinical efficacy significantly.

  13. Conductometric nitrate biosensor based on methyl viologen/Nafion/nitrate reductase interdigitated electrodes.

    Science.gov (United States)

    Xuejiang, Wang; Dzyadevych, Sergei V; Chovelon, Jean-Marc; Renault, Nicole Jaffrezic; Ling, Chen; Siqing, Xia; Jianfu, Zhao

    2006-04-15

    A highly sensitive, fast and stable conductometric enzyme biosensor for determination of nitrate in water is reported for the first time. The biosensor electrodes were modified by methyl viologen mediator mixed with nitrate reductase (NR) from Aspergillus niger by cross-linking with glutaraldehyde in the presence of bovine serum albumin and Nafion((R)) cation-exchange polymer. The process parameters for the fabrication of the enzyme electrode and various experimental variables such as pH, the enzyme loading and time of immobilization in glutaralaldehyde vapor were investigated with regard to their influence on sensitivity, limit of detection, dynamic range and operational and storage stability. The biosensor can reach 95% of steady-state conductance value in about 15s. Linear calibration in the range of 0.02 and 0.25 mM with detection limits of 0.005 mM nitrate was obtained with a signal-to-noise ratio of 3. When stored in 5 mM phosphate buffer (pH 7.5) at 4 degrees C, the sensor showed good stability over 2 weeks.

  14. Activation of the MAP Kinase Cascade by Exogenous Calcium-Sensing Receptor

    Energy Technology Data Exchange (ETDEWEB)

    Hobson, Susan A.; Wright, Jay W.; Lee, Fred; Mcneil, Scott; Bilderback, Tim R.; Rodland, Karin D.

    2003-02-01

    In Rat-1 fibroblasts and ovarian surface epithelial cells, extracellular calcium induces a proliferative response which appears to be mediated by the G-protein coupled Calcium-sensing Receptor (CaR), as expression of the non-functional CaR-R795W mutant inhibits both thymidine incorporation and activation of the extracellular-regulated kinase (ERK) in response to calcium. In this report we utilized CaR-transfected HEK293 cells to demonstrate that functional CaR is necessary and sufficient for calcium-induced ERK activation. CaR-dependent ERK activation was blocked by co-expression of the Ras dominant-negative mutant, Ras N17, and by exposure to the phosphatidyl inositol 3' kinase inhibitors wortmannin and LY294002. In contrast to Rat-1 fibroblasts, CaR-mediated in vitro kinase activity of ERK2 was unaffected by tyrosine kinase inhibitor herbimycin in CaR-transfected HEK293 cells. These results suggest that usage of distinct pathways downstream of the CaR varies in a cell-type specific manner, suggesting a potential mechanism by which activation of the CaR could couple to distinct calcium-dependent responses.

  15. Determination of major sodium iodide symporter (NIS) inhibitors in drinking waters using ion chromatography with conductivity detector.

    Science.gov (United States)

    Cengiz, Mehmet Fatih; Bilgin, Ayse Kevser

    2016-02-20

    Goiter is an important health problem all over the world and iodine deficiency is its most common cause. Perchlorate, thiocyanate and nitrate (called as major NIS inhibitors) are known to competitively inhibit iodide uptake by the thyroid gland and thus, human exposure to major NIS inhibitors is a public health concern. In this study, an ion chromatographic method for the determination of most common NIS inhibitor ions in drinking waters was developed and validated. This is the first study where an analytical method is used for the determination of major NIS inhibitors in drinking water by an ion chromatography system in a single run. Chromatographic separations were achieved with an anion-exchange column and separated ions were identified by a conductivity detector. The method was found to be selective, linear, precise accurate and true for all of interested ions. The limits of the detections (LOD) were estimated at 0.003, 0.004 and 0.025mgL(-1) for perchlorate, thiocyanate and nitrate, respectively. Possible interference ions in drinking waters were examined for the best separation of NIS inhibitors. The excellent method validation data and proficiency test result (Z-score for nitrate: -0.1) of the FAPAS(®) suggested that the developed method could be applied for determination of NIS inhibitor residues in drinking waters. To evaluate the usefulness of the method, 75 drinking water samples from Antalya/Turkey were analyzed for NIS inhibitors. Perchlorate concentrations in the samples ranged from not detected (less than LOD) to 0.07±0.02mgL(-1) and the range of nitrate concentrations were found to be 3.60±0.01mgL(-1) and 47.42±0.40mgL(-1). No thiocyanate residues were detected in tested drinking water samples.

  16. [Calcium metabolism characteristics in microgravity].

    Science.gov (United States)

    Grigor'ev, A I; Larina, I M; Morukov, B V

    1999-06-01

    The results of research of calcium exchange parameters at cosmonauts taken part in long space flights (SF) onboard of orbital stations "SALUT" and "MIR" within 1978-1998 were generalized. The analysis of data received during observation of 44 cosmonauts (18 of them have taken part in long SF twice) was done. The observation was carried out before and after SF by duration 30-438 days. The content of a total calcium in blood serum was increased basically by the increase of its ionized fraction after flights of moderate (3-6 months) and large duration (6-14 months) along with the significant increase of PTH and decrease of calcitonin levels. The content of osteocalcin after SF was increased. Three cosmonauts participated in research of calcium kinetics using stable isotopes before, in time and after a 115-day SF. Reduction of intestinal absorption, excretion through a gastrointestinal tract, and increase of calcium excretion with urine were marked in time of SF. In early postflight period a level of intestinal absorption, on the average, was much lower than in SF, and the calcium removal through intestine was increased. Both renal and intestinal excretion of calcium were not normalized in 3.5-4.5 months after end of SF. Increase of resorbtive processes in bone tissues which induced negative bone balance during flight was observed in all test subjects, proceeding from estimations of speed of the basic calcium flows made on the basis of mathematical modeling. The conclusion about decrease in speed of bone tissue remodeling and strengthening of its resorption proves to be true by data of research of biochemical and endocrine markers.

  17. Calcium wave of tubuloglomerular feedback.

    Science.gov (United States)

    Peti-Peterdi, János

    2006-08-01

    ATP release from macula densa (MD) cells into the interstitium of the juxtaglomerular (JG) apparatus (JGA) is an integral component of the tubuloglomerular feedback (TGF) mechanism that controls the glomerular filtration rate. Because the cells of the JGA express a number of calcium-coupled purinergic receptors, these studies tested the hypothesis that TGF activation triggers a calcium wave that spreads from the MD toward distant cells of the JGA and glomerulus. Ratiometric calcium imaging of in vitro microperfused isolated JGA-glomerulus complex dissected from rabbits was performed with fluo-4/fura red and confocal fluorescence microscopy. Activation of TGF by increasing tubular flow rate at the MD rapidly produced a significant elevation in intracellular Ca(2+) concentration ([Ca(2+)](i)) in extraglomerular mesangial cells (by 187.6 +/- 45.1 nM) and JG renin granular cells (by 281.4 +/- 66.6 nM). Subsequently, cell-to-cell propagation of the calcium signal at a rate of 12.6 +/- 1.1 microm/s was observed upstream toward proximal segments of the afferent arteriole and adjacent glomeruli, as well as toward intraglomerular elements including the most distant podocytes (5.9 +/- 0.4 microm/s). The same calcium wave was observed in nonperfusing glomeruli, causing vasoconstriction and contractions of the glomerular tuft. Gap junction uncoupling, an ATP scavenger enzyme cocktail, and pharmacological inhibition of P(2) purinergic receptors, but not adenosine A(1) receptor blockade, abolished the changes in [Ca(2+)](i) and propagation of the calcium wave. These studies provided evidence that both gap junctional communication and extracellular ATP are integral components of the TGF calcium wave.

  18. Fractionation of Nitrogen and Oxygen Isotopes During Microbial Nitrate Reduction

    Science.gov (United States)

    Lehmann, M. F.; Bernasconi, S. M.; Reichert, P.; Barbieri, A.; McKenzie, J. A.

    2001-12-01

    Lakes represent an important continental sink of fixed nitrogen. Besides the burial of particulate nitrogen, fixed nitrogen is eliminated from lakes by emission of N2 and N2O to the atmosphere during dissimilative nitrate reduction within suboxic and anoxic waters or sediments. The understanding and quantification of this efficient nitrogen removal process in eutrophic lakes is crucial for nitrogen budget modelling and the application and evaluation of lake restoration measures. In order to use natural abundance N and O isotope ratios as tracers for microbial nitrate reduction and to obtain quantitative estimates on its intensity, it is crucial to constrain the associated isotope fractionation. This is the first report of nitrogen and oxygen isotope effects associated with microbial nitrate reduction in lacustrine environments. Nitrate reduction in suboxic and anoxic waters of the southern basin of Lake Lugano (Switzerland) is demonstrated by a progressive nitrate depletion coupled to increasing δ 15N and δ 18O values for residual nitrate. 15N and 18O enrichment factors (ɛ ) were estimated using a closed-system (Rayleigh-distillation) model and a dynamic reaction-diffusion model. Calculated enrichment factors ɛ ranged between -11.2 and -22‰ for 15N and between -6.6 and -11.3‰ for 18O with both nitrogen and oxygen isotope fractionation being greatest during times with the highest nitrate reduction rates. The closed-system model neglects vertical diffusive mixing and does not distinguish between sedimentary and water-column nitrate reduction. Therefore, it tends to underestimate the intrinsic isotope effect of microbial nitrate reduction. Based upon results from earlier studies that indicate that nitrate reduction in sediments displays a highly reduced N-isotope effect (Brandes and Devol, 1997), model-derived enrichment factors could be used to discern the relative importance of nitrate reduction in the water column and in the sediment. Sedimentary nitrate

  19. [Calcium absorption by the rat from various milks in relation to their total phosphorus and lactose contents].

    Science.gov (United States)

    Fournier, P; Dupuis, Y; Fournier, A

    1976-01-01

    The absorption of calcium corresponds to a strictly determined mechanism inhibited by phosphates and activited by carbohydrates. We investigate in what extent the absorption of milk calcium from various species has the same proceeding. 4 months old rats are given orally solutions of CaCl2 alone or in combination with sodium dihydrogen phosphate or lactose or these both compounds. We compare calcium absorption of these solutions to that of milk from woman, cow or sow, or to dilutions of these two latter milks. All these fluids are dosed so that they correspond each other by their respective content in total calcium, total phosphorus and lactose. Each solution contains 45Ca. Blood samples 1,30, 4, 6 and 24 hours after ingestion allow establishing the variations of plasma radioactivity. Rats are sacrified after 24 hours. In certain cases, samples from digestive tube contents and feces provide a coefficient of calcium absorption. The osseous retention is obtained from femur radioactivity. In breif, we may consider that milks from cow and sow provide calcium the absorption of which is settled after their respective content of total phosphorus and lactose. Opposed effects of these inhibitors and activators of calcium absorption compensate so that calcium from these milks is just a little better utilized by adult rat than calcium from an isocalcic solution of CaCl2. Calcium from woman milk, rich in carbohydrates, poor in total phosphorus is better absorbed than that from the two latters, however less than we might expect from its high lactose content. We may wonder that calcium utilization from cow milk is as moderate as that of a solution of CaCl2. But skeleton mineralization which may be fulfilled by milk is made better because of that: it is not chloride but calcium phosphate which ensures this mineralization, a phosphate which alone would impair this mineralization without the compensative role of lactose.

  20. Elevation of extracellular Ca2+ induces store-operated calcium entry via calcium-sensing receptors: a pathway contributes to the proliferation of osteoblasts.

    Directory of Open Access Journals (Sweden)

    Fen Hu

    Full Text Available AIMS: The local concentration of extracellular Ca(2+ ([Ca(2+]o in bone microenvironment is accumulated during bone remodeling. In the present study we investigated whether elevating [Ca(2+]o induced store-operated calcium entry (SOCE in primary rat calvarial osteoblasts and further examined the contribution of elevating [Ca(2+]o to osteoblastic proliferation. METHODS: Cytosolic Ca(2+ concentration ([Ca(2+]c of primary cultured rat osteoblasts was detected by fluorescence imaging using calcium-sensitive probe fura-2/AM. Osteoblastic proliferation was estimated by cell counting, MTS assay and ATP assay. Agonists and antagonists of calcium-sensing receptors (CaSR as well as inhibitors of phospholipase C (PLC, SOCE and voltage-gated calcium (Cav channels were applied to study the mechanism in detail. RESULTS: Our data showed that elevating [Ca(2+]o evoked a sustained increase of [Ca(2+]c in a dose-dependent manner. This [Ca(2+]c increase was blocked by TMB-8 (Ca(2+ release inhibitor, 2-APB and BTP-2 (both SOCE blockers, respectively, whereas not affected by Cav channels blockers nifedipine and verapamil. Furthermore, NPS2143 (a CaSR antagonist or U73122 (a PLC inhibitor strongly reduced the [Ca(2+]o-induced [Ca(2+]c increase. The similar responses were observed when cells were stimulated with CaSR agonist spermine. These data indicated that elevating [Ca(2+]o resulted in SOCE depending on the activation of CaSR and PLC in osteoblasts. In addition, high [Ca(2+]o significantly promoted osteoblastic proliferation, which was notably reversed by BAPTA-AM (an intracellular calcium chelator, 2-APB, BTP-2, TMB-8, NPS2143 and U73122, respectively, but not affected by Cav channels antagonists. CONCLUSIONS: Elevating [Ca(2+]o induced SOCE by triggering the activation of CaSR and PLC. This process was involved in osteoblastic proliferation induced by high level of extracellular Ca(2+ concentration.