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Sample records for 13c octanoic acid

  1. 13C labelled cholesteryl octanoate breath test for assessing pancreatic exocrine insufficiency

    PubMed Central

    Ventrucci, M; Cipolla, A; Ubalducci, G; Roda, A; Roda, E

    1998-01-01

    Background—A non-invasive test for assessment of fat digestion has been developed based on the intraluminal hydrolysis of cholesteryl-[1-13C]octanoate by pancreatic esterase. 
Aims—To determine the diagnostic performance of this breath test in the assessment of exocrine pancreatic function. 
Methods—The test was performed in 20 healthy controls, 22 patients with chronic pancreatic disease (CPD), four with biliopancreatic diversion (BPD), and 32 with non-pancreatic digestive diseases (NPD); results were compared with those of other tubeless tests (faecal chymotrypsin and fluorescein dilaurate test). 
Results—Hourly recoveries of 13CO2 were significantly lower in CPD when compared with healthy controls or NPD. In patients with CPD with mild to moderate insufficiency, the curve of 13CO2 recovery was similar to that of healthy controls, while in those with severe insufficiency it was flat. In three patients with CPD with severe steatorrhoea, a repeat test after pancreatic enzyme supplementation showed a significant rise in 13CO2 recovery. The four BPD patients had low and delayed 13CO2 recovery. Only eight of the 32 patients with NPD had abnormal breath test results. There was a significant correlation between the results of the breath test and those of faecal chymotrypsin, the fluorescein dilaurate test, and faecal fat measurements. For the diagnosis of pancreatic disease using the three hour cumulative 13CO2 recovery test, the sensitivity was 68.2% and specificity 75.0%; values were similar to those of the other two tubeless pancreatic function tests. In seven healthy controls, nine patients with CPD, and nine with NPD a second breath test was performed using Na-[1-13C]octanoate and a pancreatic function index was calculated as the ratio of 13C recovery obtained in the two tests: at three hours this index was abnormal in eight patients with CPD and in three with NPD. 
Conclusion—The cholesteryl-[1-13C]octanoate breath test can be useful for the

  2. 40 CFR 721.5385 - Octanoic acid, hydrazide.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Octanoic acid, hydrazide. 721.5385... Substances § 721.5385 Octanoic acid, hydrazide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as octanoic acid, hydrazide (PMN P-92-1086) is subject...

  3. [*C]octanoic acid breath test to measure gastric emptying rate of solids.

    PubMed

    Maes, B D; Ghoos, Y F; Rutgeerts, P J; Hiele, M I; Geypens, B; Vantrappen, G

    1994-12-01

    We have developed a breath test to measure solid gastric emptying using a standardized scrambled egg test meal (250 kcal) labeled with [14C]octanoic acid or [13C]octanoic acid. In vitro incubation studies showed that octanoic acid is a reliable marker of the solid phase. The breath test was validated in 36 subjects by simultaneous radioscintigraphic and breath test measurements. Nine healthy volunteers were studied after intravenous administration of 200 mg erythromycin and peroral administration of 30 mg propantheline, respectively. Erythromycin significantly enhanced gastric emptying, while propantheline significantly reduced gastric emptying rates. We conclude that the [*C]octanoic breath test is a promising and reliable test for measuring the gastric emptying rate of solids. PMID:7995200

  4. Production of ω-hydroxy octanoic acid with Escherichia coli.

    PubMed

    Kirtz, Marko; Klebensberger, Janosch; Otte, Konrad B; Richter, Sven M; Hauer, Bernhard

    2016-07-20

    The present proof-of-concept study reports the construction of a whole-cell biocatalyst for the de novo production of ω-hydroxy octanoic acid. This was achieved by hijacking the natural fatty acid cycle and subsequent hydroxylation using a specific monooxygenase without the need for the additional feed of alkene-like precursors. For this, we used the model organism Escherichia coli and increased primarily the release of the octanoic acid precursors by overexpressing the plant thioesterase FatB2 from Cuphea hookeriana in a β-oxidation deficient strain, which lead to the production of 2.32mM (8.38mggcww(-1)) octanoic acid in 24h. In order to produce the corresponding ω-hydroxy derivative, we additionally expressed the engineered self-sufficient monooxygenase fusion protein CYP153AMaq(G307A)-CPRBM3 within the octanoic acid producing strain. With this, we finally produced 234μM (0.95mggcww(-1)) ω-hydroxy octanoic acid in a 20h fed-batch set-up. PMID:27184430

  5. Octanoic acid confers to royal jelly varroa-repellent properties

    NASA Astrophysics Data System (ADS)

    Nazzi, Francesco; Bortolomeazzi, Renzo; Della Vedova, Giorgio; Del Piccolo, Fabio; Annoscia, Desiderato; Milani, Norberto

    2009-02-01

    The mite Varroa destructor Anderson & Trueman is a parasite of the honeybee Apis mellifera L. and represents a major threat for apiculture in the Western world. Reproduction takes place only inside bee brood cells that are invaded just before sealing; drone cells are preferred over worker cells, whereas queen cells are not normally invaded. Lower incidence of mites in queen cells is at least partly due to the deterrent activity of royal jelly. In this study, the repellent properties of royal jelly were investigated using a lab bioassay. Chemical analysis showed that octanoic acid is a major volatile component of royal jelly; by contrast, the concentration is much lower in drone and worker larval food. Bioassays, carried out under lab conditions, demonstrated that octanoic acid is repellent to the mite. Field studies in bee colonies confirmed that the compound may interfere with the process of cell invasion by the mite.

  6. Octanoic acid confers to royal jelly varroa-repellent properties.

    PubMed

    Nazzi, Francesco; Bortolomeazzi, Renzo; Della Vedova, Giorgio; Del Piccolo, Fabio; Annoscia, Desiderato; Milani, Norberto

    2009-02-01

    The mite Varroa destructor Anderson & Trueman is a parasite of the honeybee Apis mellifera L. and represents a major threat for apiculture in the Western world. Reproduction takes place only inside bee brood cells that are invaded just before sealing; drone cells are preferred over worker cells, whereas queen cells are not normally invaded. Lower incidence of mites in queen cells is at least partly due to the deterrent activity of royal jelly. In this study, the repellent properties of royal jelly were investigated using a lab bioassay. Chemical analysis showed that octanoic acid is a major volatile component of royal jelly; by contrast, the concentration is much lower in drone and worker larval food. Bioassays, carried out under lab conditions, demonstrated that octanoic acid is repellent to the mite. Field studies in bee colonies confirmed that the compound may interfere with the process of cell invasion by the mite. PMID:19050844

  7. Cytochrome c catalyses the formation of pentyl radical and octanoic acid radical from linoleic acid hydroperoxide.

    PubMed Central

    Iwahashi, Hideo; Nishizaki, Koji; Takagi, Ichiro

    2002-01-01

    A reaction of 13-hydroperoxide octadecadienoic acid (13-HPODE) with cytochrome c was analysed using ESR, HPLC-ESR and HPLC-ESR-MS by the combined use of the spin-trapping technique. The ESR, HPLC-ESR and HPLC-ESR-MS analyses showed that cytochrome c catalyses formation of pentyl and octanoic acid radicals from 13-HPODE. On the other hand, only the alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone/octanoic acid radical adduct was detected in the elution profile of HPLC-ESR for a mixture of 13-HPODE with haematin, indicating that haematin catalyses the formation of octanoic acid radical. In addition, the reaction of 13-HPODE with cytochrome c was inhibited by chlorogenic acid, caffeic acid and ferulic acid via two possible mechanisms, i.e. reducing cytochrome c (chlorogenic acid and caffeic acid) and scavenging the radical intermediates (chlorogenic acid, caffeic acid and ferulic acid). PMID:11742529

  8. Structure and polymer form of poly-3-hydroxyalkanoates produced by Pseudomonas oleovorans grown with mixture of sodium octanoate/undecylenic acid and sodium octanoate/5-phenylvaleric acid.

    PubMed

    Ho, I-Ching; Yang, Sheng-Pin; Chiu, Wen-Yen; Huang, Shih-Yow

    2007-01-30

    PHAs (poly-3-hydroxyalkanoates) obtained by Pseudomonas oleovorans grown with mixed carbon sources were investigated. Mixed carbon sources were sodium octanoate/undecylenic acid and sodium octanoate/5-phenylvaleric acid. Effect of carbon source in pre-culture on PHAs structure was investigated. Main fermentation was conducted with mixture of sodium octanoate/undecylenic acid, and PHA contained both saturated and unsaturated units. When more undecylenic acid was used in the medium, the ratio of unsaturated unit increased and the T(g) of the products also changed. The PHA grown with mixture of sodium octanoate and undecylenic acid was a random copolymer, which was determined by DSC analysis. Using mixed carbon sources of sodium octanoate and 5-phenylvaleric acid, highest dry cell weight and PHA concentration were obtained when 0.02g or 0.04g of 5-phenylvaleric acid were added in 50mL medium. Cultured with sodium octanoate and 5-phenylvaleric acid, PHA containing HO (3-hydroxyoctanoate) unit and HPV (3-hydroxy-5-phenylvalerate) unit was produced. T(g) of the products fell between those of pure PHO and pure PHPV. By means of DSC analysis and fractionation method, the PHA obtained was regarded as a random copolymer. PMID:16919325

  9. Role of octanoic and decanoic acids in the control of seizures.

    PubMed Central

    Sills, M A; Forsythe, W I; Haidukewych, D

    1986-01-01

    Octanoic and decanoic acid, the major constituents of the Medium Chain Triglyceride (MCT) Emulsion diet, have been detected in appreciable quantities in the peripheral blood of children with intractable seizures treated with the MCT diet. Serum concentrations of these acids as well as beta hydroxybutyrate and acetoacetate rose as the diet was introduced and on full diet showed pronounced diurnal variation and low concentrations in the morning. No correlation between octanoic and decanoic acid concentrations and control of seizures was established, but further studies with octanoic and decanoic acid using animal models are necessary to assess the role of these acids and of control of seizures. PMID:3492967

  10. Octanoic acid in alcohol-responsive essential tremor

    PubMed Central

    McCrossin, Gayle; Lungu, Codrin; Considine, Elaine; Toro, Camilo; Nahab, Fatta B.; Auh, Sungyoung; Buchwald, Peter; Grimes, George J.; Starling, Judith; Potti, Gopal; Scheider, Linda; Kalowitz, Daniel; Bowen, Daniel; Carnie, Andrea; Hallett, Mark

    2013-01-01

    Objective: To assess safety and efficacy of an oral, single, low dose of octanoic acid (OA) in subjects with alcohol-responsive essential tremor (ET). Methods: We conducted a double-blind, placebo-controlled, crossover, phase I/II clinical trial evaluating the effect of 4 mg/kg OA in 19 subjects with ET. The primary outcome was accelerometric postural tremor power of the dominant hand 80 minutes after administration. Secondary outcomes included digital spiral analysis, pharmacokinetic sampling, as well as safety measures. Results: OA was safe and well tolerated. Nonserious adverse events were mild (Common Terminology Criteria for Adverse Events grade 1) and equally present after OA and placebo. At the primary outcome, OA effects were not different from placebo. Secondary outcome analyses of digital spiral analysis, comparison across the entire time course in weighted and nonweighted accelerometry, as well as nondominant hand tremor power did not show a benefit of OA over placebo. The analysis of individual time points showed that OA improved tremor at 300 minutes (dominant hand, F1,16 = 5.49, p = 0.032 vs placebo), with a maximum benefit at 180 minutes after OA (both hands, F1,16 = 6.1, p = 0.025). Conclusions: Although the effects of OA and placebo at the primary outcome were not different, secondary outcome measures suggest superiority of OA in reducing tremor at later time points, warranting further trials at higher dose levels. Classification of evidence: This study provides Class I evidence that a single 4-mg/kg dose of OA is not effective in reducing postural tremor in patients with ET at a primary outcome of 80 minutes, but is effective for a secondary outcome after 180 minutes. PMID:23408867

  11. Evolution for exogenous octanoic acid tolerance improves carboxylic acid production and membrane integrity.

    PubMed

    Royce, Liam A; Yoon, Jong Moon; Chen, Yingxi; Rickenbach, Emily; Shanks, Jacqueline V; Jarboe, Laura R

    2015-05-01

    Carboxylic acids are an attractive biorenewable chemical, but as with many biorenewables, their toxicity to microbial biocatalysts limits their fermentative production. While it is generally accepted that membrane damage is the main mechanism of fatty acid toxicity, previous metabolic engineering efforts that increased membrane integrity did not enable increased carboxylic acid production. Here we used an evolutionary approach to improve tolerance to exogenous octanoic acid, with the goal of learning design strategies from this evolved strain. This evolution of an Escherichia coli MG1655 derivative at neutral pH in minimal media produced a strain with increased tolerance not only to octanoic acid, but also to hexanoic acid, decanoic acid, n-butanol and isobutanol. This evolved strain also produced carboxylic acids at a 5-fold higher titer than its parent strain when expressing the Anaerococcus tetradius thioesterase. While it has been previously suggested that intracellular acidification may contribute to carboxylic acid toxicity, we saw no evidence that the evolved strain has increased resistance to this acidification. Characterization of the evolved strain membrane showed that it had significantly altered membrane polarization (fluidity), integrity (leakage) and composition relative to its parent. The changes in membrane composition included a significant increase in average lipid length in a variety of growth conditions, including 30°C, 42°C, carboxylic acid challenge and ethanol challenge. The evolved strain has a more dynamic membrane composition, showing both a larger number of significant changes and larger fold changes in the relative abundance of membrane lipids. These results highlight the importance of the cell membrane in increasing microbial tolerance and production of biorenewable fuels and chemicals. PMID:25839166

  12. Pharmacological modulation of gastric emptying rate of solids as measured by the carbon labelled octanoic acid breath test: influence of erythromycin and propantheline.

    PubMed Central

    Maes, B D; Hiele, M I; Geypens, B J; Rutgeerts, P J; Ghoos, Y F; Vantrappen, G

    1994-01-01

    The *C (13C or 14C) labelled octanoic acid breath test was recently developed to measure the gastric emptying rate of solids. This study aimed to investigate whether it is sensitive enough to detect pharmacologically induced changes in the gastric emptying rate. Nine healthy volunteers were studied in basal condition, after intravenous administration of 200 mg erythromycin, and after peroral administration of 30 mg propantheline. Erythromycin significantly enhanced gastric emptying in all subjects, with an increase of the gastric emptying coefficient (p = 0.0043) in eight of nine and a fall in both the gastric half emptying time (p = 0.0020) and the lag phase (p = 0.0044) in all nine. Propantheline significantly reduced the gastric emptying rate, with a decreased gastric emptying coefficient (p = 0.0007) and an increased gastric half emptying time (p = 0.0168) in all subjects, but no change in the lag phase (p = 0.1214). Further mathematical analysis showed that breath sampling at 15 minutes intervals over a four hour period is recommended to guarantee accuracy and the discriminative value of the breath test in various gastric emptying patterns. In conclusion the *C labelled octanoic acid breath test is sufficiently sensitive to show pharmacologically induced changes of gastric emptying rates of solids. PMID:8150342

  13. Synthesis of [1-.sup.13C]pyruvic acid], [2-.sup.13C]pyruvic acid], [3-.sup.13C]pyruvic acid] and combinations thereof

    DOEpatents

    Martinez, Rodolfo A.; Unkefer, Clifford J.; Alvarez, Marc A.

    2009-09-01

    The present invention is directed to labeled compounds, of the formulae ##STR00001## wherein C* is each independently selected from the group consisting of .sup.13C and .sup.12C with the proviso that at least one C* is .sup.13C, each hydrogen of the methylene group can independently be either hydrogen or deuterium, the methyl group includes either zero or three deuterium atoms, Q is from the group of sulfide, sulfinyl, and sulfone, Z is an aryl group from the group of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure ##STR00002## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently from the group of hydrogen, a C.sub.1-C.sub.4 lower alkyl, a halogen, and an amino group from the group of NH.sub.2, NHR and NRR' where R and R' are each independently from the group of a C.sub.1-C.sub.4 lower alkyl, a phenyl, and an alkoxy group, and the methyl group can include either zero or three deuterium atoms.

  14. Synthesis of [1-.sup.13C]pyruvic acid], [2-.sup.13C]pyruvic acid], [3-.sup.13C]pyruvic acid] and combinations thereof

    DOEpatents

    Martinez, Rodolfo A. , Unkefer; Clifford J. , Alvarez; Marc A.

    2012-06-12

    The present invention is directed to the labeled compounds, ##STR00001## wherein C* is each either .sup.13C and .sup.12C where at least one C* is .sup.13C, each hydrogen of the methylene group is hydrogen or deuterium, the methyl group includes either zero or three deuterium atoms, Q is sulfide, sulfinyl, or sulfone, Z is an aryl group such as 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, or a phenyl group ##STR00002## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently either hydrogen, a C.sub.1-C.sub.4 lower alkyl, a halogen, and an amino group such as NH.sub.2, NHR and NRR' where R and R' are each independently either a C.sub.1-C.sub.4 lower alkyl, a phenyl, and an alkoxy group, and the methyl group can include either zero or three deuterium atoms. The present invention is also directed to the labeled compounds ##STR00003##

  15. Bromoxynil octanoate

    Integrated Risk Information System (IRIS)

    Bromoxynil octanoate ; CASRN 1689 - 99 - 2 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinog

  16. New insights into the toxicity mechanism of octanoic and decanoic acids on Saccharomyces cerevisiae.

    PubMed

    Borrull, Anna; López-Martínez, Gema; Poblet, Montse; Cordero-Otero, Ricardo; Rozès, Nicolas

    2015-05-01

    Octanoic (C8) and decanoic (C10) acids are produced in hypoxic conditions by the yeast Saccharomyces cerevisiae as by-products of its metabolism and are considered fermentation inhibitors in the presence of ethanol at acidic pH. This study aims to broaden our understanding of the physiological limits between toxicity and ester production in yeast cells. To this end, the non-inhibitory concentration (NIC) and maximum inhibitory concentration (MIC) values were first established for C8 and C10 at physiological pH (5.8) without ethanol. The results showed that when these acids were added to culture medium at these values, they tended to accumulate in different cellular fractions of the yeast. While C8 was almost entirely located in the cell wall fraction, C10 was found in the endocellular fraction. Cell fatty acid detoxification was also different; while the esterification of fatty acids was more efficient in the case of C10, the peroxisome was activated regardless of which fatty acid was added. Furthermore, the study of the Pdr12 and Tpo1 transporters that evolved during the detoxification process revealed that C8 was mostly expelled by the Pdr12 carrier, which was related to higher β-oxidative damage in the presence of endocellular C10. C10 is more toxic at lower concentrations than C8. Although they are produced by yeast, the resulting intracellular medium-chain fatty acids (MCFAs) caused a level of toxicity which promoted cell death. However, MCFAs are involved in the production of beverage flavours. PMID:25773463

  17. Tunable macromolecular-based materials for the adsorption of perfluorooctanoic and octanoic acid anions.

    PubMed

    Karoyo, Abdalla H; Wilson, Lee D

    2013-07-15

    The sorption properties of tunable urethane-based copolymer materials containing β-cyclodextrin (β-CD) were evaluated with perfluorooctanoic acid (PFOA) and octanoic acid (OA) anions in aqueous solutions, respectively. The copolymer materials are herein referred to as macromolecular imprinted materials (MIMs) since their design strategy incorporates a porogen macromolecule (β-CD) within a cross-linked hexamethylene diisocyanate (HDI) framework. We report the tunable uptake of OA and PFOA anions from aqueous solution with variable adsorption modes, in accordance with the composition of the MIMs. The sorption results with granular activated carbon (GAC) were compared at 295 K and pH values exceeding the pKa values of each adsorbate. The BET and Sips models provided estimates of the monolayer sorption capacity (Qm) and related equilibrium sorption parameters. The Qm value for GAC with PFOA was ~1.4 mmol/g; whereas, a greater Qm value for PFOA (up to 2.6 mmol/g) was observed with the MIMs. GAC displays greater sorption capacity toward PFOA at relatively low Ce values and saturation of the monolayer occurs at Ce~0.5 mM. The MIMs/PFOA system displays monolayer completion at values of Ce~1 mM and multilayer sorption when Ce>1mM. Equilibrium sorption of PFOA onto MIMs occurs at the inclusion sites of β-CD and interstitial binding sites of the polymeric framework. Surface adsorption of the PFOA anion occurs between the PFOA carboxylate head group and dipolar interstitial domains of the cross-linker framework. The MIMs sorbents display tunable and favorable binding with PFOA and OA anions where the uptake (per mg MIMs) with PFOA was ~5-33% (5 μM-5 mM) and with OA was ~0.5-5% (1-20 mM). The overall sorptive uptake of OA and PFOA anions by the MIMs sorbents meets or exceeds those observed for GAC. PMID:23664395

  18. Dose-escalation study of octanoic acid in patients with essential tremor

    PubMed Central

    Voller, Bernhard; Lines, Emily; McCrossin, Gayle; Tinaz, Sule; Lungu, Codrin; Grimes, George; Starling, Judith; Potti, Gopal; Haubenberger, Dietrich

    2016-01-01

    BACKGROUND. Recently, 1-octanol has been shown to have efficacy in treating patients with essential tremor (ET). The primary metabolite of 1-octanol is octanoic acid (OA), which is now thought to be the active substance that mediates tremor suppression. Our aim was to describe the maximum tolerated dose (MTD) of oral OA in patients with ET and assess the pharmacokinetics (PK) and pharmacodynamics (PD) profile of OA. METHODS. The MTD was studied using an open-label, single-ascending 3 + 3 dose–escalation design. Predefined single doses ranged from 8 to 128 mg/kg, with grade 2 adverse events (AEs) defined as dose-limiting toxicity. Tremor was assessed using accelerometry, digital spiral analysis, and a standard clinical rating scale at baseline and up to 600 minutes after intake. Safety assessments and PK sampling were also performed. RESULTS. Dose-limiting toxicity was not reached. The most frequent AE was mild abdominal discomfort. Exposure (AUC) increased linearly with the dose. Secondary efficacy measures suggested a dose-dependent reduction of tremor. Accordingly, a single unified PK/PD model with an effect compartment and sigmoid maximum effect (Emax) response could be built that accounted well for the time profiles of plasma concentrations as well as effects on tremor severity across the 5 dose levels. CONCLUSION. Although our trial did not reach an MTD, a dose-dependent effect was demonstrated in the PK/PD model as well as in secondary efficacy outcomes. Future studies are needed to explore the safety in higher dose ranges and to confirm dose-dependent efficacy in a placebo-controlled design. TRIAL REGISTRATION. Clinicaltrials.gov NCT01468948 FUNDING. NINDS Intramural Research Program; TG Therapeutics Inc. PMID:26927672

  19. High-field dissolution dynamic nuclear polarization of [1-(13)C]pyruvic acid.

    PubMed

    Yoshihara, Hikari A I; Can, Emine; Karlsson, Magnus; Lerche, Mathilde H; Schwitter, Juerg; Comment, Arnaud

    2016-05-14

    [1-(13)C]pyruvate is the most widely used hyperpolarized metabolic magnetic resonance imaging agent. Using a custom-built 7.0 T polarizer operating at 1.0 K and trityl radical-doped [1-(13)C]pyruvic acid, unextrapolated solution-state (13)C polarization greater than 60% was measured after dissolution and rapid transfer to a spectrometer magnet, demonstrating the signal enhancement attainable using optimized hardware. Slower rates of polarization under these conditions can be largely overcome with higher radical concentrations. PMID:27093499

  20. Production and NMR signal optimization of hyperpolarized 13C-labeled amino acids

    NASA Astrophysics Data System (ADS)

    Parish, Christopher; Niedbalski, Peter; Ferguson, Sarah; Kiswandhi, Andhika; Lumata, Lloyd

    Amino acids are targeted nutrients for consumption by cancers to sustain their rapid growth and proliferation. 13C-enriched amino acids are important metabolic tracers for cancer diagnostics using nuclear magnetic resonance (NMR) spectroscopy. Despite this diagnostic potential, 13C NMR of amino acids however is hampered by the inherently low NMR sensitivity of the 13C nuclei. In this work, we have employed a physics technique known as dynamic nuclear polarization (DNP) to enhance the NMR signals of 13C-enriched amino acids. DNP works by transferring the high polarization of electrons to the nuclear spins via microwave irradiation at low temperature and high magnetic field. Using a fast dissolution method in which the frozen polarized samples are dissolved rapidly with superheated water, injectable solutions of 13C-amino acids with highly enhanced NMR signals (by at least 5,000-fold) were produced at room temperature. Factors that affect the NMR signal enhancement levels such as the choice of free radical polarizing agents and sample preparation will be discussed along with the thermal mixing physics model of DNP. The authors would like to acknowledge the support by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

  1. Metabolism of parenterally administered fat emulsions in the rat: studies of fatty acid oxidation with 1-13C- and 8-13C-labelled triolein.

    PubMed

    Bäurle, W; Brösicke, H; Matthews, D E; Pogan, K; Fürst, P

    1998-04-01

    To reassess the hypothesis that fatty acid catabolism occurs to completion via beta-oxidation, male Sprague-Dawley rats receiving continuous total parenteral nutrition (TPN) including 43% energy as fat were infused with [1-(13)C]- or [8-(13)C]triolein. Expired CO2 was collected continuously for 4 h and its 13C:12C ratio determined by isotope-ratio mass spectrometry. Bicarbonate retention was also assessed over 4 h by infusion of NaH14CO3 and measurement of the expired 14CO2. A possible loss of label from [8-(13)C]oleic acid from the citric acid cycle via labelled acetyl-CoA without oxidation to CO2 was assessed by infusing further animals with acetate labelled with 14C either at C atoms 1 or 2 and determination of its conversion to expired 14CO2. At isotopic steady state, 63.2 (SE 1.6)% (n 8) of the infused [1-(14)C]acetate and 46.0 (SE 1.2)% (n 8) of [2-(14)C]acetate was recovered as expired 14CO2. After correction for bicarbonate retention and non-oxidative isotope loss, 37.3 (SE 1.2)% (n 20) of the [1-(13)C]triolein was found to have been oxidized, whereas 32.6 (SE 1.0)% (n 20) of the [8-(13)C]triolein was oxidized (P < or = 0.01). The lower oxidation of the C atom at position 8 of oleic acid than that at position 1 indicates incomplete oxidative breakdown of the fatty acid after entering beta-oxidation. PMID:9624230

  2. 13C-NMR spectra and contact time experiment for Skjervatjern fulvic and humic acids

    USGS Publications Warehouse

    Malcolm, R.L.

    1992-01-01

    The T(CP) and T(1p) time constants for Skjervatjern fulvic and humic acids were determined to be short with T(CP) values ranging from 0.14 ms to 0.53 ms and T(1p) values ranging from 3.3 ms to 5.9 ms. T(CP) or T(1p) time constants at a contact time of 1 ms are favorable for quantification of 13C-NMR spectra. Because of the short T(CP) values, correction factors for signal intensity for various regions of the 13C-NMR spectra would be necessary at contact times greater than 1.1 ms or less than 0.9 ms. T(CP) and T(1p) values have a limited non-homogeneity within Skjervatjern fulvic and humic acids. A pulse delay or repeat time of 700 ms is more than adequate for quantification of these 13C-NMR spectra. Paramagnetic effects in these humic substances are precluded due to low inorganic ash contents, low contents of Fe, Mn, and Co, and low organic free-radical contents. The observed T(CP) values suggest that all the carbon types in Skjervatjern fulvic and humic acids are fully cross-polarized before significant proton relaxation occurs. The 13C-NMR spectra for Skjervatjern fulvic acid is similar to most aquatic fulvic acids as it is predominantly aliphatic, low in aromaticity (fa1 = 24), low in phenolic content, high in carboxyl content, and has no resolution of a methoxyl peak. The 13C-NMR spectra for Skjervatjern humic acid is also similar to most other aquatic humic acids in that it is also predominantly aliphatic, high in aromaticity (fa1 = 38), moderate in phenolic content, moderate in carboxyl content, and has a clear resolution of a methoxyl carbon region. After the consideration of the necessary 13C-NMR experimental conditions, these spectra are considered to be quantitative. With careful consideration of the previously determined 13C-NMR experimental conditions, quantitative spectra can be obtained for humic substances in the future from the HUMEX site. Possible changes in humic substances due to acidification should be determined from 13C-NMR data.

  3. Effect of preduodenal lipase inhibition in suckling rats on dietary octanoic acid (C8:0) gastric absorption and plasma octanoylated ghrelin concentration.

    PubMed

    Lemarié, F; Cavalier, J-F; Garcia, C; Boissel, F; Point, V; Catheline, D; Legrand, P; Carrière, F; Rioux, V

    2016-09-01

    Part of medium chain fatty acids (MCFAs) coming from dietary triglycerides (TGs) can be directly absorbed through the gastric mucosa after the action of preduodenal lipase (lingual lipase in the rat). MCFA gastric absorption, particularly that of octanoic acid (C8:0), may have a physiological importance in the octanoylation of ghrelin, the orexigenic gastric peptide acting as an endogenous ligand of the hypothalamic growth hormone secretagogue receptor 1a (GHSR-1a). However, the amount of C8:0 absorbed in the stomach and its metabolic fate still haven't been clearly characterized. The purpose of the present study was to further characterize and quantify the importance of preduodenal lipase activity on the release and gastric absorption of dietary C8:0 and on the subsequent ghrelin octanoylation in the stomach mucosa. Fifteen days old rats received fat emulsions containing triolein or [1,1,1-(13)C]-Tri-C8:0 and a specific inhibitor of preduodenal lipase, 5-(2-(benzyloxy)ethoxy)-3-(3-phenoxyphenyl)-1,3,4-oxadiazol-2(3H)-one or BemPPOX. The fate of the (13)C-C8:0 was followed in rat tissues after 30 and 120min of digestion and octanoylated ghrelin was measured in the plasma. This work (1) demonstrates that part of C8:0 coming from Tri-C8:0 is directly absorbed at the gastric level, (2) allows the estimation of C8:0 gastric absorption level (1.3% of the (13)C-C8:0 in sn-3 position after 30min of digestion), as well as (3) the contribution of rat lingual lipase to total lipolysis and to duodenal absorption of dietary FAs (at least 30%), (4) shows no short-term effect of dietary Tri-C8:0 consumption and subsequent increase of C8:0 gastric tissue content on plasma octanoylated ghrelin concentration. PMID:27317984

  4. Characterisation of the 1H and 13C NMR spectra of methylcitric acid

    NASA Astrophysics Data System (ADS)

    Krawczyk, Hanna; Martyniuk, Tomasz

    2007-06-01

    Methylcitric acid (MCA) was synthesised in Reformatsky reaction (2 RS, 3 RS stereoisomers) and in the nucleophilic addition (2 RS, 3 SR stereoisomers). The stereoselectivity of these reactions was analysed. 1H and 13C NMR spectra of diastereoisomers of methylcitric acid were recorded and interpreted. The values of 1H chemical shifts and 1H- 1H coupling constants were analysed. Proton-decoupled high-resolution 13C NMR spectra of MCA diastereoisomers were measured in a series of dilute water solutions of various acidities. These data may provide a basis for unequivocal determination of the presence of MCA in the urine samples of patients' suffering from propionic acidemia, methylmalonic aciduria, or holocarboxylase synthetase deficiency. NMR spectroscopy enables determination of MCA diastereoisomers in body fluids and can be a complementary and useful diagnostic tool.

  5. Synthesis of [.sup.13C] and [.sup.2H] substituted methacrylic acid, [.sup.13C] and [.sup.2H] substituted methyl methacrylate and/or related compounds

    DOEpatents

    Alvarez, Marc A.; Martinez, Rodolfo A.; Unkefer, Clifford J.

    2008-01-22

    The present invention is directed to labeled compounds of the formulae ##STR00001## wherein Q is selected from the group consisting of --S--, --S(.dbd.O)--, and --S(.dbd.O).sub.2--, Z is selected from the group consisting of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure ##STR00002## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently selected from the group consisting of hydrogen, a C.sub.1-C.sub.4 lower alkyl, a halogen, and an amino group selected from the group consisting of NH.sub.2, NHR and NRR' where R and R' are each independently selected from the group consisting of a C.sub.1-C.sub.4 lower alkyl, an aryl, and an alkoxy group, and X is selected from the group consisting of hydrogen, a C.sub.1-C.sub.4 lower alkyl group, and a fully-deuterated C.sub.1-C.sub.4 lower alkyl group. The present invention is also directed to a process of preparing labeled compounds, e.g., process of preparing [.sup.13C]methacrylic acid by reacting a (CH.sub.3CH.sub.2O--.sup.13C(O)--.sup.13CH.sub.2)-- aryl sulfone precursor with .sup.13CHI to form a (CH.sub.3CH.sub.2O--.sup.13C(O)--.sup.13C(.sup.13CH.sub.3).sub.2)-- aryl sulfone intermediate, and, reacting the (CH.sub.3CH.sub.2O--.sup.13C(O)--.sup.13C(.sup.13CH.sub.3).sub.2)-- aryl sulfone intermediate with sodium hydroxide, followed by acid to form [.sup.13C]methacrylic acid. The present invention is further directed to a process of preparing [.sup.2H.sub.8]methyl methacrylate by reacting a (HOOC--C(C.sup.2H.sub.3).sub.2-- aryl sulfinyl intermediate with CD.sub.3I to form a (.sup.2H.sub.3COOC--C(C.sup.2H.sub.3).sub.2)-- aryl sulfinyl intermediate, and heating the(.sup.2H.sub.3COOC--C(C.sup.2H.sub.3).sub.2)-- aryl sulfinyl intermediate at temperatures and for time sufficient to form [.sup.2H.sub.8]methyl methacrylate.

  6. Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids

    PubMed Central

    You, Le; Page, Lawrence; Feng, Xueyang; Berla, Bert; Pakrasi, Himadri B.; Tang, Yinjie J.

    2012-01-01

    Microbes have complex metabolic pathways that can be investigated using biochemistry and functional genomics methods. One important technique to examine cell central metabolism and discover new enzymes is 13C-assisted metabolism analysis 1. This technique is based on isotopic labeling, whereby microbes are fed with a 13C labeled substrates. By tracing the atom transition paths between metabolites in the biochemical network, we can determine functional pathways and discover new enzymes. As a complementary method to transcriptomics and proteomics, approaches for isotopomer-assisted analysis of metabolic pathways contain three major steps 2. First, we grow cells with 13C labeled substrates. In this step, the composition of the medium and the selection of labeled substrates are two key factors. To avoid measurement noises from non-labeled carbon in nutrient supplements, a minimal medium with a sole carbon source is required. Further, the choice of a labeled substrate is based on how effectively it will elucidate the pathway being analyzed. Because novel enzymes often involve different reaction stereochemistry or intermediate products, in general, singly labeled carbon substrates are more informative for detection of novel pathways than uniformly labeled ones for detection of novel pathways3, 4. Second, we analyze amino acid labeling patterns using GC-MS. Amino acids are abundant in protein and thus can be obtained from biomass hydrolysis. Amino acids can be derivatized by N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (TBDMS) before GC separation. TBDMS derivatized amino acids can be fragmented by MS and result in different arrays of fragments. Based on the mass to charge (m/z) ratio of fragmented and unfragmented amino acids, we can deduce the possible labeled patterns of the central metabolites that are precursors of the amino acids. Third, we trace 13C carbon transitions in the proposed pathways and, based on the isotopomer data, confirm whether these

  7. Strength and limits using 13C phospholipid fatty acid analysis in soil ecology

    NASA Astrophysics Data System (ADS)

    Watzinger, Andrea

    2016-04-01

    This presentation on microbial phospholipid biomarkers, their isotope analysis and their ability to reveal soil functions summarizes experiences gained by the author for more than 10 years. The amount and composition of phospholipid fatty acids (PLFAs) measured in environmental samples strongly depend on the methodology. To achieve comparable results the extraction, separation and methylation method must be kept constant. PLFAs patterns are sensitive to microbial community shifts even though the taxonomic resolution of PLFAs is low. The possibility to easily link lipid biomarkers with stable isotope techniques is identified as a major advantage when addressing soil functions. Measurement of PLFA isotopic ratios is sensitive and enables detecting isotopic fractionation. The difference between the carbon isotopic ratio of single PLFAs and their substrate (δ13C) can vary between -6 and +11‰. This difference derives from the fractionation during biosynthesis and from substrate inhomogeneity. Consequently, natural abundance studies are restricted to quantifying substrate uptake of the total microbial biomass. In contrast, artificial labelling enables quantifying carbon uptake into single PLFAs, but labelling success depends on homogeneous and undisturbed label application. Current developments in microbial ecology (e.g. 13C and 15N proteomics) and isotope techniques (online monitoring of CO2 isotope ratios) will likely improve soil functional interpretations in the future. 13C PLFA analysis will continue to contribute because it is affordable, sensitive and allows frequent sampling combined with the use of small amounts of 13C label.

  8. Uniformly sup 13 C-labeled algal protein used to determine amino acid essentiality in vivo

    SciTech Connect

    Berthold, H.K.; Hachey, D.L.; Reeds, P.J.; Klein, P.D. ); Thomas, O.P. ); Hoeksema, S. )

    1991-09-15

    The edible alga Spirulina platensis was uniformly labeled with {sup 13}C by growth in an atmosphere of pure {sup 13}CO{sub 2}. The labeled biomass was then incorporated into the diet of a laying hen for 27 days. The isotopic enrichment of individual amino acids in egg white and yolk proteins, as well as in various tissues of the hen at the end of the feeding period, was analyzed by negative chemical ionization gas chromatography/mass spectrometry. The amino acids of successive eggs showed one of two exclusive enrichment patterns: complete preservation of the intact carbon skeleton or extensive degradation and resynthesis. The same observation was made in tissue proteins. These patterns were cleanly divided according to known nutritional amino acid essentiality/nonessentiality but revealed differences in labeling among the nonessential amino acids: most notable was that proline accretion was derived entirely from the diet. Feeding uniformly {sup 13}C-labeled algal protein and recovering and analyzing de novo-synthesized protein provides a useful method to examine amino acid metabolism and determine conditional amino acid essentially in vivo.

  9. Uniformly 13C-labeled algal protein used to determine amino acid essentiality in vivo.

    PubMed Central

    Berthold, H K; Hachey, D L; Reeds, P J; Thomas, O P; Hoeksema, S; Klein, P D

    1991-01-01

    The edible alga Spirulina platensis was uniformly labeled with 13C by growth in an atmosphere of pure 13CO2. The labeled biomass was then incorporated into the diet of a laying hen for 27 days. The isotopic enrichment of individual amino acids in egg white and yolk proteins, as well as in various tissues of the hen at the end of the feeding period, was analyzed by negative chemical ionization gas chromatography/mass spectrometry. The amino acids of successive eggs showed one of two exclusive enrichment patterns: complete preservation of the intact carbon skeleton or extensive degradation and resynthesis. The same observation was made in tissue proteins. These patterns were cleanly divided according to known nutritional amino acid essentiality/nonessentiality but revealed differences in labeling among the nonessential amino acids: most notable was that proline accretion was derived entirely from the diet. Feeding uniformly 13C-labeled algal protein and recovering and analyzing de novo-synthesized protein provides a useful method to examine amino acid metabolism and determine conditional amino acid essentially in vivo. Images PMID:11607211

  10. Behavior of spores of Penicillium roquefortii during fed-batch bioconversion of octanoic acid into 2-heptanone

    SciTech Connect

    Larroche, C.; Besson, I.; Gros, J.B. . Lab. de Genie Chimique Biologique)

    1994-09-05

    The bioconversion of octanoic acid into 2-heptanone by spores of Penicillium roquefortii is performed using a fed-batch technique with pH control by addition of the liquid substrate itself. The early stage of this process takes place with a high bioconversion rate and high yield. These values then decrease as a result of germination and growth of the biocatalyst. An optimization strategy for the process would thus be to improve the characteristics of this first period, i.e., increase its duration and the reaction rate. An increase in duration is evidenced in two cases: (1) under oxygen limitation; and (2) when the spore content in the medium is less than 10[sup 7] spores/mL. These conditions give insufficient overall bioconversion rates; better optimization should be achieved without oxygen limitation and with high spore content. Characterization of the first period by material and bioenergetic balances suggests that an increase in the ethanol content of the medium, which acts as an energy source and a permeabilizer, and the use of a specific inhibitor of the Krebs cycle, may be a way to further improve the biocatalyst performance and stability.

  11. The effect of sample hydration on 13C CPMAS NMR spectra of fulvic acids

    USGS Publications Warehouse

    Hatcher, P.G.; Wilson, M.A.

    1991-01-01

    Three fulvic acids, two of which have been well studied by a number of other groups (Armadale and Suwannee river fulvic acids) have been examined by high resolution solid-state 13C-NMR techniques to delineate the effect of absorbed water. Two main effects of absorbed water were observed: (1) changes in spin lattice relaxation times in the rotating frame and cross polarization times and (2) total loss of signal so that some fulvic acid is effectively in solution. These results suggest that discrepancies in the literature concerning observed relative signal intensities from different structural groups are due to absorbed water and emphasize the necessity for proper precautionary drying before spectroscopic analysis. ?? 1991.

  12. Enhancing Phospholipid Fatty Acid Profiling of Soil Bacterial Communities via Substrate- Specific 13C-labelling

    NASA Astrophysics Data System (ADS)

    Evershed, R. P.; Maxfield, P. J.; Bingham, E. M.; Dildar, N.; Brennand, E. L.; Hornibrook, E.

    2008-12-01

    A range of culture-independent methods, has recently emerged to study environmental microorganisms in situ[1]. One such method is phospholipid fatty acid (PLFA) analysis, wherein these ubiquitous membrane lipids provide a powerful tool for the study of unculturable soil microorganisms. PLFA analyses have been used to investigate the impacts of a wide range of environmental factors on the soil microbial community. An acknowledged shortcoming of the PLFAs approach is the lack the chemotaxonoic specificity, which restricts the ability of the method to probe the activities of specific functional groups of the microbial community selectively. However, the selectivity of PLFAs analyses can be enhanced by incubating soils with 13C- labelled substrates followed by gas chromatography-combustion-isotope ratio mass spectrometry to reveal the specific PLFAs incorporating the 13C-label. The application of this approach will be demonstrated through our recent work on methanotrophic bacteria in soils. We applied this approach initially to mineral soils[2] and then extended chemotaxonomic assessments by using a combination of 13C-labelled PLFAs and hopanoids [3]. We have used this approach to explore the properties of high affinity methanotrophs in a range of environments, investigating the relationship between methane oxidation rates and the nature and magnitude of the methanotrophic community for the first time[4,5] More recently we extended the technique using a novel time series 13C-labelling of PLFAs[6] to estimate the rate and progression of 13C- label incorporation and turnover of methanotrophic populations. This modified approach has been used to investigate the impacts of various environmental variables, e.g. soil type, vegetation cover and land use, on the methanotrophic biomass[7.8]. The unique nature of the 13CH4 as a gaseous substate/carbon source means that can be readily introduced into soils via a specific subset of the soil microbial biomass, thereby offering many

  13. Biosynthetic production of universally (13)C-labelled polyunsaturated fatty acids as reference materials for natural health product research.

    PubMed

    Le, Phuong Mai; Fraser, Catherine; Gardner, Graeme; Liang, Wei-Wan; Kralovec, Jaroslav A; Cunnane, Stephen C; Windust, Anthony J

    2007-09-01

    Long-chain polyunsaturated fatty acids (LCPUFA) including eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) have become important natural health products with numerous proven benefits related to brain function and cardiovascular health. Not only are omega-3 fatty acids available in a plethora of dietary supplements, but they are also increasingly being incorporated as triglycerides into conventional foods, including bread, milk, yoghurt and confectionaries. Recently, transgenic oil seed crops and livestock have been developed that enhance omega-3 fatty acid content. This diverse array of matrices presents a difficult analytical challenge and is compounded further by samples generated through clinical research. Stable isotope (13)C-labelled LCPUFA standards offer many advantages as research tools because they may be distinguished from their naturally abundant counterparts by mass spectrometry and directly incorporated as internal standards into analytical procedures. Further, (13)C-labelled LCPUFAs are safe to use as metabolic tracers to study uptake and metabolism in humans. Currently, (13)C-labelled LCPUFAs are expensive, available in limited supply and not in triglyceride form. To resolve these issues, marine heterotrophic microorganisms are being isolated and screened for LCPUFA production with a view to the efficient biosynthetic production of U-(13)C-labelled fatty acids using U-(13)C glucose as a carbon source. Of 37 isolates obtained, most were thraustochytrids, and either DHA or omega-6 docosapentaenoic acid (22:5n-6) were produced as the major LCPUFA. The marine protist Hyalochlorella marina was identified as a novel source of EPA and omega-3 docosapentaenoic acid (22:5n-3). As proof of principle, gram-level production of (13)C-labelled DHA has been achieved with high chemical purity ( >99%) and high (13)C incorporation levels (>90%), as confirmed by NMR and MS analyses. Finally, U-(13)C-DHA was enzymatically re-esterified to

  14. {sup 13}C-enrichment at carbons 8 and 2 of uric acid after {sup 13}C-labeled folate dose in man

    SciTech Connect

    Baggott, Joseph E.; Gorman, Gregory S.; Morgan, Sarah L.; Tamura, Tsunenobu . E-mail: tamurat@uab.edu

    2007-09-21

    To evaluate folate-dependent carbon incorporation into the purine ring, we measured {sup 13}C-enrichment independently at C{sub 2} and C{sub 8} of urinary uric acid (the final catabolite of purines) in a healthy male after an independent oral dose of [6RS]-5-[{sup 13}C]-formyltetrahydrofolate ([6RS]-5-H{sup 13}CO-H{sub 4}folate) or 10-H{sup 13}CO-7,8-dihydrofolate (10-H{sup 13}CO-H{sub 2}folate). The C{sub 2} position was {sup 13}C-enriched more than C{sub 8} after [6RS]-5-H{sup 13}CO-H{sub 4}folate, and C{sub 2} was exclusively enriched after 10-H{sup 13}CO-H{sub 2}folate. The enrichment of C{sub 2} was greater from [6RS]-5-H{sup 13}CO-H{sub 4}folate than 10-H{sup 13}CO-H{sub 2}folate using equimolar bioactive doses. Our data suggest that formyl C of [6RS]-10-H{sup 13}CO-H{sub 4}folate was not equally utilized by glycinamide ribotide transformylase (enriches C{sub 8}) and aminoimidazolecarboxamide ribotide (AICAR) transformylase (enriches C{sub 2}), and the formyl C of 10-H{sup 13}CO-H{sub 2}folate was exclusively used by AICAR transformylase. 10-HCO-H{sub 2}folate may function in vivo as the predominant substrate for AICAR transformylase in humans.

  15. A 13C{31P} REDOR NMR Investigation of the Role of Glutamic Acid Residues in Statherin-Hydroxyapatite Recognition

    PubMed Central

    Ndao, Moise; Ash, Jason T.; Breen, Nicholas F.; Goobes, Gil; Stayton, Patrick S.; Drobny, Gary P.

    2011-01-01

    The side chain carboxyl groups of acidic proteins found in the extra-cellular matrix (ECM) of mineralized tissues play a key role in promoting or inhibiting the growth of minerals such as hydroxyapatite (HAP), the principal mineral component of bone and teeth. Among the acidic proteins found in the saliva is statherin, a 43-residue tyrosine-rich peptide that is a potent lubricant in the salivary pellicle and an inhibitor of both HAP crystal nucleation and growth. Three acidic amino acids – D1, E4, and E5 – are located in the N-terminal 15 amino acid segment, with a fourth amino acid, E26, located outside the N-terminus. We have utilized 13C{31P} REDOR NMR to analyze the role played by acidic amino acids in the binding mechanism of statherin to the HAP surface by measuring the distance between the δ-carboxyl 13C spins of the three glutamic acid side chains of statherin (residues E4, E5, E26) and 31P spins of the phosphate groups at the HAP surface. 13C{31P} REDOR studies of glutamic-5-13C acid incorporated at positions E4 and E26 indicate a 13C–31P distance of more than 6.5 Å between the side chain carboxyl 13C spin of E4 and the closest 31P in the HAP surface. In contrast, the carboxyl 13C spin at E5 has a much shorter 13C–31P internuclear distance of 4.25±0.09 Å, indicating that the carboxyl group of this side chain interacts directly with the surface. 13C T1ρ and slow-spinning MAS studies indicate that the motions of the side chains of E4 and E5 are more restricted than that of E26. Together, these results provide further insight into the molecular interactions of statherin with HAP surfaces. PMID:19678690

  16. Bioconversion of N-octane to octanoic acid by a recombinant Escherichia coli cultured in a two-liquid phase bioreactor

    SciTech Connect

    Favre-Bulle, O.; Schouten, T.; Kingma, J.; Witholt, B. )

    1991-04-01

    The alk genes from the catabolic OCT plasmid of Pseudomonas oleovorans, which encode the enzymes involved in the oxidation of n-alkanes to carboxylic acids, were introduced into E. coli W3110. The resulting recombinant converts n-octane in a two-liquid phase medium into the corresponding alkanoate and excretes this compound into the aqueous phase. The rate of octanoic acid production by the recombinant E. coli is equal to or better than the alkane oxidation rate of P. oleovorans, suggesting that two-liquid phase fermentations with E. coli might have future industrial applications.

  17. Production of 3-Oxo-2-(2'-pentenyl)-cyclopentane-1-octanoic Acid in the Fungus Aspergillus oryzae: A Step Towards Heterologous Production of Pyrethrins in Fungi.

    PubMed

    Mohamed, Maged E; Pahirulzaman, Khomaizon A K; Lazarus, Colin M

    2016-03-01

    Pyrethrins are natural insecticides, which accumulate to high concentrations in pyrethrum (Chrysanthemum cinerariaefolium) flowers. Synthetic pyrethroids are more stable, more efficacious and cheaper, but contemporary requirements for safe and environmentally friendly pesticides encourage a return to the use of natural pyrethrins, and this would be favoured by development of an efficient route to their production by microbial fermentation. The biosynthesis of pyrethrins involves ester linkage between an acid moiety (chrysanthemoyl or pyrethroyl, synthesised via the mevalonic acid pathway from glucose), and an alcohol (pyrethrolone). Pyrethrolone is generated from 3-oxo-2-(2'-pentenyl)-cyclopentane-1-octanoic acid, which originates from α-linolenic acid via the jasmonic acid biosynthetic cascade. The first four genes in this cascade, encoding lipoxygenase 2, allene-oxide synthase, allene-oxide cyclase 2 and 12-oxophytodienoic acid reductase 3, were amplified from an Arabidopsis thaliana cDNA library, cloned in a purpose-built fungal multigene expression vector and expressed in Aspergillus oryzae. HPLC-MS analysis of the transgenic fungus homogenate gave good evidence for the presence of 3-oxo-2-(2'-pentenyl)-cyclopentane-1-octanoic acid. PMID:26718544

  18. Differential effects of octanoate and heptanoate on myocardial metabolism during extracorporeal membrane oxygenation in an infant swine model.

    PubMed

    Kajimoto, Masaki; Ledee, Dolena R; Olson, Aaron K; Isern, Nancy G; Des Rosiers, Christine; Portman, Michael A

    2015-10-01

    Nutritional energy support during extracorporeal membrane oxygenation (ECMO) should promote successful myocardial adaptation and eventual weaning from the ECMO circuit. Fatty acids (FAs) are a major myocardial energy source, and medium-chain FAs (MCFAs) are easily taken up by cell and mitochondria without membrane transporters. Odd-numbered MCFAs supply carbons to the citric acid cycle (CAC) via anaplerotic propionyl-CoA as well as acetyl-CoA, the predominant β-oxidation product for even-numbered MCFA. Theoretically, this anaplerotic pathway enhances carbon entry into the CAC, and provides superior energy state and preservation of protein synthesis. We tested this hypothesis in an immature swine model undergoing ECMO. Fifteen male Yorkshire pigs (26-45 days old) with 8-h ECMO received either normal saline, heptanoate (odd-numbered MCFA), or octanoate (even-numbered MCFA) at 2.3 μmol·kg body wt(-1)·min(-1) as MCFAs systemically during ECMO (n = 5/group). The 13-carbon ((13)C)-labeled substrates ([2-(13)C]lactate, [5,6,7-(13)C3]heptanoate, and [U-(13)C6]leucine) were systemically infused as metabolic markers for the final 60 min before left ventricular tissue extraction. Extracted tissues were analyzed for the (13)C-labeled and absolute concentrations of metabolites by nuclear magnetic resonance and gas chromatography-mass spectrometry. Octanoate produced markedly higher myocardial citrate concentration, and led to a higher [ATP]-to-[ADP] ratio compared with other groups. Unexpectedly, octanoate and heptanoate increased the flux of propionyl-CoA relative to acetyl-CoA into the CAC compared with control. MCFAs promoted increases in leucine oxidation, but were not associated with a difference in protein synthesis rate. In conclusion, octanoate provides energetic advantages to the heart over heptanoate. PMID:26232235

  19. Differential Effects Of Octanoate And Heptanoate On Myocardial Metabolism During Extracorporeal Membrane Oxygenation In An Infant Swine Model

    SciTech Connect

    Kajimoto, Masaki; Ledee, Dolena R.; Isern, Nancy G.; Olson, Aaron; Des Rosiers, Christine; Portman, Michael A.

    2015-10-01

    Background: Nutritional energy support during extracorporeal membrane oxygenation (ECMO) should promote successful myocardial adaptation and eventual weaning from the ECMO circuit. Fatty acids (FAs) are a major myocardial energy source, and medium-chain FAs (MCFAs) are easily taken up by cell and mitochondria without membrane transporters. Oddnumbered MCFAs supply carbons to the citric acid cycle (CAC) via anaplerotic propionyl-CoA as well as acetyl-CoA, the predominant betaoxidation product for even-numbered MCFA. Theoretically, this anaplerotic pathway enhances carbon entry into the CAC, and provides superior energy state and preservation of protein synthesis. We tested this hypothesis in an immature swine model undergoing ECMO. Methods: Fifteen male Yorkshire pigs (26-45 days old) with 8-hour ECMO were received either normal saline, heptanoate (odd-numbered MCFA) or octanoate (even-numbered MCFA) at 2.3 μmol/kg body wt/min as MCFAs systemically during ECMO (n = 5 per group). The 13-Carbon (13C)-labeled substrates ([2-13C]lactate, [5,6,7-13C3]heptanoate and [U-13C6]leucine) were systemically infused as metabolic markers for the final 60 minutes before left ventricular tissue extraction. Extracted tissues were analyzed for the 13C-labeled and absolute concentrations of metabolites by nuclear magnetic resonance and gas chromatography-mass spectrometry. Results: Octanoate produced markedly higher myocardial citrate concentration, and led to a higher [ATP]/[ADP] ratio compared with other http://mc.manuscriptcentral.com/jpen Journal of Parenteral and Enteral Nutrition For Peer Review groups. Unexpectedly, octanoate increased the flux of propionyl-CoA relative to acetyl-CoA into the CAC as well as heptanoate. MCFAs promoted increases in leucine oxidation, but were not associated with a difference in fractional protein synthesis rate. Conclusion: Octanoate provides energetic advantages to the heart over heptanoate, while preserving protein synthesis.

  20. 13C NMR study of the generation of C2- and C3-deuterated lactic acid by tumoral pancreatic islet cells exposed to D-[1-13C]-, D-[2-13C]- and D-[6-13C]-glucose in 2H2O.

    PubMed

    Willem, R; Biesemans, M; Kayser, F; Malaisse, W J

    1994-03-01

    Tumoral pancreatic islet cells of the RIN5mF line were incubated for 120 min in media prepared in 2H2O and containing D-[1-13C]glucose, D-[2-13C]glucose, and D-[6-13C]glucose. The generation of C2- and C3-deuterated lactic acid was assessed by 13C NMR. The interpretation of experimental results suggests that a) the efficiency of deuteration on the C1 of D-fructose 6-phosphate does not exceed about 47% and 4% in the phosphoglucoisomerase and phosphomannoisomerase reactions, respectively; b) approximately 38% of the molecules of D-glyceraldehyde 3-phosphate generated from D-glucose escape deuteration in the sequence of reactions catalyzed by triose phosphate isomerase and aldolase; and c) about 41% of the molecules of pyruvate generated by glycolysis are immediately converted to lactate, the remaining 59% of pyruvate molecules undergoing first a single or double back-and-forth interconversion with L-alanine. It is proposed that this methodological approach, based on high resolution 13C NMR spectroscopy, may provide novel information on the regulation of back-and-forth interconversion of glycolytic intermediates in intact cells as modulated, for instance, by enzyme-to-enzyme tunneling. PMID:8057796

  1. High Yield of Wax Ester Synthesized from Cetyl Alcohol and Octanoic Acid by Lipozyme RMIM and Novozym 435

    PubMed Central

    Kuo, Chia-Hung; Chen, Hsin-Hung; Chen, Jiann-Hwa; Liu, Yung-Chuan; Shieh, Chwen-Jen

    2012-01-01

    Wax esters are long-chain esters that have been widely applied in premium lubricants, parting agents, antifoaming agents and cosmetics. In this study, the biocatalytic preparation of a specific wax ester, cetyl octanoate, is performed in n-hexane using two commercial immobilized lipases, i.e., Lipozyme® RMIM (Rhizomucor miehei) and Novozym® 435 (Candida antarctica). Response surface methodology (RSM) and 5-level-4-factor central composite rotatable design (CCRD) are employed to evaluate the effects of reaction time (1–5 h), reaction temperature (45–65 °C), substrate molar ratio (1–3:1), and enzyme amount (10%–50%) on the yield of cetyl octanoate. Using RSM to optimize the reaction, the maximum yields reached 94% and 98% using Lipozyme® RMIM and Novozym® 435, respectively. The optimum conditions for synthesis of cetyl octanoate by both lipases are established and compared. Novozym® 435 proves to be a more efficient biocatalyst than Lipozyme® RMIM. PMID:23109878

  2. Metabolic pathways for ketone body production. /sup 13/C NMR spectroscopy of rat liver in vivo using /sup 13/C-multilabeled fatty acids

    SciTech Connect

    Pahl-Wostl, C.; Seelig, J.

    1986-11-04

    The hormonal regulation of ketogenesis in the liver of living rat has been studied noninvasively with /sup 13/C nuclear magnetic resonance. The spatial selection for the liver was better than 90%, with extrahepatic adipose tissue contribution only a very small amount of signal. The metabolic activities of the liver were investigated by infusion of /sup 13/C-labeled butyrate in the jugular vein of the anesthetized rat. The rate of butyrate infusion was chosen to be close to the maximum oxidative capacity of the rat liver, and the /sup 13/C signal intensities were enhanced by using doubly labeled (1,3-/sup 13/C)butyrate as a substrate. Different /sup 13/C NMR spectra and hence different metabolites were observed depending on the hormonal state of the animal. The /sup 13/C NMR studies demonstrate that even when rate of acetyl-CoA production are high, the disposal of this compound is not identical in fasted and diabetic animals. This supports previous suggestions that the redox state of the mitochondrion represents the most important factor in regulation. For a given metabolic state of the animal, different signal intensities were obtained depending on whether butyrate was labeled at C-1, C-3, or C-1,3. From the ratios of incorporation of /sup 13/C label into the carbons of 3-hydroxybutyrate, it could be estimated that a large fraction of butyrate evaded ..beta..-oxidation to acetyl-CoA but was converted directly to acetoacetyl-CoA. /sup 13/C-labeled glucose could be detected in vivo in the liver of diabetic rats.

  3. Low-field thermal mixing in [1-(13)C] pyruvic acid for brute-force hyperpolarization.

    PubMed

    Peat, David T; Hirsch, Matthew L; Gadian, David G; Horsewill, Anthony J; Owers-Bradley, John R; Kempf, James G

    2016-07-28

    We detail the process of low-field thermal mixing (LFTM) between (1)H and (13)C nuclei in neat [1-(13)C] pyruvic acid at cryogenic temperatures (4-15 K). Using fast-field-cycling NMR, (1)H nuclei in the molecule were polarized at modest high field (2 T) and then equilibrated with (13)C nuclei by fast cycling (∼300-400 ms) to a low field (0-300 G) that activates thermal mixing. The (13)C NMR spectrum was recorded after fast cycling back to 2 T. The (13)C signal derives from (1)H polarization via LFTM, in which the polarized ('cold') proton bath contacts the unpolarised ('hot') (13)C bath at a field so low that Zeeman and dipolar interactions are similar-sized and fluctuations in the latter drive (1)H-(13)C equilibration. By varying mixing time (tmix) and field (Bmix), we determined field-dependent rates of polarization transfer (1/τ) and decay (1/T1m) during mixing. This defines conditions for effective mixing, as utilized in 'brute-force' hyperpolarization of low-γ nuclei like (13)C using Boltzmann polarization from nearby protons. For neat pyruvic acid, near-optimum mixing occurs for tmix∼ 100-300 ms and Bmix∼ 30-60 G. Three forms of frozen neat pyruvic acid were tested: two glassy samples, (one well-deoxygenated, the other O2-exposed) and one sample pre-treated by annealing (also well-deoxygenated). Both annealing and the presence of O2 are known to dramatically alter high-field longitudinal relaxation (T1) of (1)H and (13)C (up to 10(2)-10(3)-fold effects). Here, we found smaller, but still critical factors of ∼(2-5)× on both τ and T1m. Annealed, well-deoxygenated samples exhibit the longest time constants, e.g., τ∼ 30-70 ms and T1m∼ 1-20 s, each growing vs. Bmix. Mixing 'turns off' for Bmix > ∼100 G. That T1m≫τ is consistent with earlier success with polarization transfer from (1)H to (13)C by LFTM. PMID:27362505

  4. Determination of sup 13 C labeling pattern of citric acid cycle intermediates by gas chromatography-mass spectrometry

    SciTech Connect

    Di Donato, L.; Montgomery, J.A.; Des Rosiers, C.; David, F.; Garneau, M.; Brunengraber, H. )

    1990-02-26

    Investigations of the regulation of the citric acid cycle require determination of labeling patterns of cycle intermediates. These were assayed to date, using infusion of: (i) ({sup 14}C)tracer followed by chemical degradation of intermediates and (ii) ({sup 13}C)tracer followed by NMR analysis of intermediates. The authors developed a strategy to analyze by GC-MS the ({sup 13}C) labeling pattern of {mu}mole samples of citrate (CIT), isocitrate (ICIT), 2-ketoglutarate (2-KG), glutamate (GLU) and glutamine (GLN). These are enzymatically or chemically converted to 2-KG, ICIT, 4-aminobutyrate (GABA) and 2-hydroxyglutarate (2-OHG). GC-MS analyses of TMS or TBDMS derivatives of these compounds yield the enrichment of each carbon. The authors confirmed the identity of each fragment using the spectra of (1-{sup 13}C), (5-{sup 13}C), (2,3,3,4,4-{sup 2}H{sub 5})glutamate and (1-{sup 13}C), (1,4-{sup 13}C)GABA.

  5. Testing compound-specific δ13C of amino acids in mussels as a new approach to determine the average 13C values of primary production in littoral ecosystems

    NASA Astrophysics Data System (ADS)

    Vokhshoori, N. L.; Larsen, T.; McCarthy, M.

    2012-12-01

    Compound-specific isotope analysis of amino acids (CSI-AA) is a technique used to decouple trophic enrichment patterns from source changes at the base of the food web. With this new emerging tool, it is possible to precisely determine both trophic position and δ15N or δ13C source values in higher feeding organisms. While most work to date has focused on nitrogen (N) isotopic values, early work has suggested that δ13C CSI-AA has great potential as a new tracer both to a record δ13C values of primary production (unaltered by trophic transfers), and also to "fingerprint" specific carbon source organisms. Since essential amino acids (EAA) cannot be made de novo in metazoans but must be obtained from diet, the δ13C value of the primary producer is preserved through the food web. Therefore, the δ13C values of EAAs act as a unique signature of different primary producers and can be used to fingerprint the dominant carbon (C) source driving primary production at the base of the food web. In littoral ecosystems, such as the California Upwelling System (CUS), the likely dominant C sources of suspended particulate organic matter (POM) pool are kelp, upwelling phytoplankton or estuarine phytoplankton. While bulk isotopes of C and N are used extensively to resolve relative consumer hierarchy or shifting diet in a food web, we found that the δ13C bulk values in mussels cannot distinguish exact source in littoral ecosystems. Here we show 15 sites within the CUS, between Cape Blanco, OR and La Jolla, CA where mussels were sampled and analyzed for both bulk δ13C and CSI-AA. We found no latitudinal trends, but rather average bulk δ13C values for the entire coastal record were highly consistent (-15.7 ± 0.9‰). The bulk record would suggest either nutrient provisioning from kelp or upwelled phytoplankton, but 13C-AA fingerprinting confines these two sources to upwelling. This suggests that mussels are recording integrated coastal phytoplankton values, with the enriched

  6. Prominent bacterial heterotrophy and sources of 13C-depleted fatty acids to the interior Canada Basin

    NASA Astrophysics Data System (ADS)

    Shah, S. R.; Griffith, D. R.; Galy, V.; McNichol, A. P.; Eglinton, T. I.

    2013-11-01

    In recent decades, the Canada Basin of the Arctic Ocean has experienced rapidly decreasing summer sea ice coverage and freshening of surface waters. It is unclear how these changes translate to deeper waters, particularly as our baseline understanding of organic carbon cycling in the deep basin is quite limited. In this study, we describe full-depth profiles of the abundance, distribution and carbon isotopic composition of fatty acids from suspended particulate matter at a seasonally ice-free station and a semi-permanently ice-covered station. Fatty acids, along with suspended particulate organic carbon (POC), are more concentrated and 13C-enriched under ice cover than in ice-free waters. But this influence, apparent at 50 m depth, does not propagate downward below 150 m depth, likely due to the weak biological pump in the central Canada Basin. Branched fatty acids have δ13C values that are similar to suspended POC at all depths and are more 13C-enriched than even-numbered saturated fatty acids at depths above 3000 m. These are likely to be produced in situ by heterotrophic bacteria incorporating organic carbon that is isotopically similar to total suspended POC. Below surface waters, there is also the suggestion of a source of saturated even-numbered fatty acids which could represent contributions from laterally advected organic carbon and/or from chemoautotrophic bacteria. At 3000 m depth and below, a greater relative abundance of long-chain (C20-24), branched and unsaturated fatty acids is consistent with a stronger influence of re-suspended sedimentary organic carbon. At these deep depths, two individual fatty acids (C12 and iso-C17) are significantly depleted in 13C, allowing for the possibility that methane oxidizing bacteria contribute fatty acids, either directly to suspended particulate matter or to shallow sediments that are subsequently mobilized and incorporated into suspended particulate matter within the deep basin.

  7. (13)C NMR characterization of triacylglycerols of Moringa oleifera seed oil: an "oleic-vaccenic acid" oil.

    PubMed

    Vlahov, Giovanna; Chepkwony, Paul Kiprono; Ndalut, Paul K

    2002-02-27

    The composition of acyl chains and their positions in the triacylglycerols of the oil extracted from seeds of Moringa oleifera were studied by (13)C NMR spectroscopy. The unsaturated chains of M. oleifera seed oil were found to comprise only mono-unsaturated fatty acids and, in particular, two omega-9 mono-unsaturated acids, (cis-9-octadecenoic (oleic acid) and cis-11-eicosenoic acids) and one omega-7 mono-unsaturated acid (cis-11-octadecenoic acid (vaccenic acid)). The mono-unsaturated fatty acids were detected as separated resonances in the spectral regions where the carbonyl and olefinic carbons resonate according to the 1,3- and 2-positions on the glycerol backbone. The unambiguous detection of vaccenic acid was also achieved through the resonance of the omega-3 carbon. The (13)C NMR methodology enabled the simultaneous detection of oleate, vaccenate, and eicosenoate chains according to their positions on the glycerol backbone (1,3- and 2-positions) through the carboxyl, olefinic, and methylene envelope carbons of the triacylglycerol acyl chains. PMID:11853466

  8. Prominent bacterial heterotrophy and sources of 13C-depleted fatty acids to the interior Canada Basin

    NASA Astrophysics Data System (ADS)

    Shah, S. R.; Griffith, D. R.; Galy, V.; McNichol, A. P.; Eglinton, T. I.

    2013-04-01

    In recent decades, the Canada Basin of the Arctic Ocean has experienced rapidly decreasing summer sea ice coverage and freshening of surface waters. It is unclear how these changes translate to depth, particularly as our baseline understanding of organic carbon cycling in the deep basin is limited. In this study, we describe full-depth profiles of the abundance, distribution and carbon isotopic composition of fatty acids from suspended particulate matter at a seasonally ice-free station and a semi-permanently ice-covered station. Fatty acids, along with suspended particulate organic carbon (POC), are more concentrated under ice cover than in ice-free waters. But this influence, apparent at 50 m depth, does not propagate downward below 150 m depth, likely due to the weak biological pump in the central Canada Basin. Branched fatty acids have δ13C values that are similar to suspended POC at all depths and are 13C-enriched compared to even-numbered saturated fatty acids at depths above 3000 m. These are likely to be produced in situ by heterotrophic bacteria incorporating organic carbon that is isotopically similar to total suspended POC. A source of saturated even-numbered fatty acids is also suggested below surface waters which could represent contributions from laterally advected organic carbon or from chemoautotrophic bacteria. At 3000 m depth and below, a greater relative abundance of long-chain (C20-24), branched and unsaturated fatty acids is consistent with a stronger influence of re-suspended sedimentary organic carbon on benthic particulate matter. At these deep depths, two individual fatty acids (C12 and iso-C17) are significantly depleted in 13C, allowing for the possibility that methane oxidizing bacteria contribute fatty acids, either directly to suspended particulate matter or to shallow sediments that are subsequently mobilized and incorporated into suspended particulate matter within the deep basin.

  9. Acid treatment biasing to C/N, δ13C and δ15N of organic matter: A Molecular insight

    NASA Astrophysics Data System (ADS)

    Brodie, C.; Casford, J.; Leng, M. J.; Zong, Y.

    2011-12-01

    It is known that acid treatment methods employed to remove inorganic carbon (IC) from sample material prior to analysis for C/N, δ13C and δ15N cause non-linear, unpredictable biasing to the organic matter (OM) fraction [1, 2, 3]. Consequently, measured C/N, δ13C and δ15N have an uncertainty much greater than instrument precision with biases for C/N reported in the range of 1 - 100, for δ13C in the range of 0.2 - 6.8 % and for δ15N in the range of 0.2 - 1.5 % [1, 2, 3], in both modern and palaeo environmental materials. Brodie et al [3] extended this investigation to a down-core lake sedimentary archive (Lake Tianyang, South China) and noted the potential for this biasing to preclude "common" interpretations of the data (e.g., C/N values as an OM provenance tool; δ13C as a proxy for changes in C3 and C4 vegetation). It is evident that the size of biasing between sample horizons varies considerably implying a differential relative reaction to acid treatment down-core (i.e., as the type, relative amount and physical state of organic components changes. We now investigate this biasing at the molecular level by employing 13C-NMR and GC-IRMS techniques on a suite of modern and palaeo environmental materials and on a lake sedimentary archive. This will provide an important insight into the effect of acid treatment on organic compounds (i.e. removal from the sample, breakdown of compounds and partial removal) and associated isotopic fractionation. From an improved understanding of the type of compounds most susceptible to alteration/removal during the acid treatment processes it will be possible to consider refinements to the acid pre-treatment process and provide information on the relative down-core changes in those compounds susceptible to change (which we may be able to glean environmental information from). [1] Brodie, C.R., Leng, M.J., Casford, J.S.L., Kendrick, C.K., Lloyd, J.M., Zong, Y.Q., and Bird, M.I. (2011) Evidence for bias in C and N concentrations

  10. Use of solid-state 13C NMR in structural studies of humic acids and humin from Holocene sediments

    USGS Publications Warehouse

    Hatcher, P.G.; VanderHart, D.L.; Earl, W.L.

    1980-01-01

    13C NMR spectra of solid humic substances in Holocene sediments have been obtained using cross polarization with magic-angle sample spinning techniques. The results demonstrate that this technique holds great promise for structural characterizations of complex macromolecular substances such as humin and humic acids. Quantifiable distinctions can be made between structural features of aquatic and terrestrial humic substances. The aliphatic carbons of the humic substances are dominant components suggestive of input from lipid-like materials. An interesting resemblance is also noted between terrestrial humic acid and humin spectra. ?? 1980.

  11. Effect of Glutamine, Glutamic Acid and Nucleotides on the Turnover of Carbon (δ13C) in Organs of Weaned Piglets

    PubMed Central

    Amorim, Alessandro Borges; Berto, Dirlei Antonio; Saleh, Mayra Anton Dib; Telles, Filipe Garcia; Denadai, Juliana Célia; Sartori, Maria Márcia Pereira; Luiggi, Fabiana Golin; Santos, Luan Sousa; Ducatti, Carlos

    2016-01-01

    Morphological and physiological alterations occur in the digestive system of weanling piglets, compromising the performance in subsequent phases. This experiment aimed at verifying the influence of glutamine, glutamate and nucleotides on the carbon turnover in the pancreas and liver of piglets weaned at 21 days of age. Four diets were evaluated: glutamine, glutamic acid or nucleotides-free diet (CD); containing 1% glutamine (GD); containing 1% glutamic acid (GAD) and containing 1% nucleotides (ND). One hundred and twenty-three piglets were utilized with three pigs slaughtered at day zero (weaning day) and three at each one of the experimental days (1, 2, 4, 5, 7, 9, 13, 20, 27, and 49 post-weaning), in order to collect organ samples, which were analyzed for the δ13C isotopic composition and compared by means of time. No differences were found (p>0.05) among treatments for the turnover of the 13C in the pancreas (T50% = 13.91, 14.37, 11.07, and 9.34 days; T95% = 46.22, 47.73, 36.79, and 31.04 days for CD, GD, GAD, and ND, respectively). In the liver, the ND presented accelerated values of carbon turnover (T50% = 7.36 and T95% = 24.47 days) in relation to the values obtained for the GD (T50% = 10.15 and T95% = 33.74 days). However, the values obtained for the CD (T50% = 9.12 and T95% = 30.31 days) and GAD (T50% = 7.83 and T95% = 26.03 days) had no differences (p>0.05) among other diets. The technique of 13C isotopic dilution demonstrated trophic action of nucleotides in the liver. PMID:26954179

  12. Effect of Glutamine, Glutamic Acid and Nucleotides on the Turnover of Carbon (δ(13)C) in Organs of Weaned Piglets.

    PubMed

    Amorim, Alessandro Borges; Berto, Dirlei Antonio; Saleh, Mayra Anton Dib; Telles, Filipe Garcia; Denadai, Juliana Célia; Sartori, Maria Márcia Pereira; Luiggi, Fabiana Golin; Santos, Luan Sousa; Ducatti, Carlos

    2016-08-01

    Morphological and physiological alterations occur in the digestive system of weanling piglets, compromising the performance in subsequent phases. This experiment aimed at verifying the influence of glutamine, glutamate and nucleotides on the carbon turnover in the pancreas and liver of piglets weaned at 21 days of age. Four diets were evaluated: glutamine, glutamic acid or nucleotides-free diet (CD); containing 1% glutamine (GD); containing 1% glutamic acid (GAD) and containing 1% nucleotides (ND). One hundred and twenty-three piglets were utilized with three pigs slaughtered at day zero (weaning day) and three at each one of the experimental days (1, 2, 4, 5, 7, 9, 13, 20, 27, and 49 post-weaning), in order to collect organ samples, which were analyzed for the δ(13)C isotopic composition and compared by means of time. No differences were found (p>0.05) among treatments for the turnover of the (13)C in the pancreas (T50% = 13.91, 14.37, 11.07, and 9.34 days; T95% = 46.22, 47.73, 36.79, and 31.04 days for CD, GD, GAD, and ND, respectively). In the liver, the ND presented accelerated values of carbon turnover (T50% = 7.36 and T95% = 24.47 days) in relation to the values obtained for the GD (T50% = 10.15 and T95% = 33.74 days). However, the values obtained for the CD (T50% = 9.12 and T95% = 30.31 days) and GAD (T50% = 7.83 and T95% = 26.03 days) had no differences (p>0.05) among other diets. The technique of (13)C isotopic dilution demonstrated trophic action of nucleotides in the liver. PMID:26954179

  13. Titration and exchange studies of liver fatty acid-binding protein with 13C-labeled long-chain fatty acids.

    PubMed

    Wang, Hsin; He, Yan; Kroenke, Christopher D; Kodukula, Sarala; Storch, Judith; Palmer, Arthur G; Stark, Ruth E

    2002-04-30

    Uniformly (13)C-labeled long-chain fatty acids were used to probe ligand binding to rat liver fatty acid-binding protein (LFABP), an atypical member of the fatty acid-binding protein (FABP) family that binds more than one molecule of long-chain fatty acid, accommodates a variety of diverse ligands, and exhibits diffusion-mediated lipid transport to membranes. Two sets of (1)H-(13)C resonances were found in a titration series of NMR spectra for oleate-LFABP complexes, indicating that two molecules of the fatty acid are situated in the protein cavity. However, no distinct resonances were observed for the excess fatty acid in solution, suggesting that at least one ligand undergoes rapid exchange with oleate in the bulk solution. An exchange rate of 54 +/- 6 s(-1) between the two sets of resonances was measured directly using (13)C z,z-exchange spectroscopy. In light of these NMR measurements, possible molecular mechanisms for the ligand-exchange process are evaluated and implications for the anomalous fatty acid transport mechanism of LFABP are discussed. PMID:11969406

  14. Advanced CPMAS-13C NMR techniques for molecular characterization of size-separated fractions from a soil humic acid.

    PubMed

    Conte, Pellegrino; Spaccini, Riccardo; Piccolo, Alessandro

    2006-09-01

    A humic acid extracted from a volcanic soil was subjected to preparative high-performance size-exclusion chromatography (HPSEC) to reduce its molecular complexity and eleven different size fractions were obtained. Cross-polarization magic-angle spinning 13C NMR (CPMAS 13C NMR) analysis performed with variable contact-time (VCT) pulse sequences showed that the largest molecular-size fractions contained aromatic, alkyl, and carbohydrate-like components. The carbohydrate-like content and the alkyl chain length seemed to decrease with decreasing molecular size. Progressive reduction of aromatic carbon atoms was also observed with decreasing molecular size of the separated fractions. Mathematical treatment of the results from VCT experiments enabled cross polarization (T (CH)) and proton spin-lattice relaxation (T(1rho)(H)) times to be related to structural differences among the size fractions. The conformational distribution indicated that the eleven size fractions could be allocated to two main groups. The first group, with larger nominal molecular sizes, was characterized by molecular domains with slower local molecular motion. The second group of size fractions, with smaller nominal molecular sizes, was characterized by a larger number of molecular domains with faster local molecular motion. The T (CH) and (T(1rho)(H)) values suggested that either condensed or strongly associated aromatic systems were predominant in the size fractions with the largest apparent molecular dimensions. PMID:16896626

  15. Human lactation: oxidation and maternal transfer of dietary (13)C-labelled α-linolenic acid into human milk.

    PubMed

    Demmelmair, Hans; Kuhn, Angelika; Dokoupil, Katharina; Hegele, Verena; Sauerwald, Thorsten; Koletzko, Berthold

    2016-06-01

    The origin of fatty acids in milk has not been elucidated in detail. We investigated the contribution of dietary α-linolenic acid (ALA) to human milk fat, its oxidation and endogenous conversion to long-chain polyunsaturated fatty acids. Ten lactating women were given (13)C-ALA orally, and breath and milk samples were collected for a five-day period, while dietary intakes were assessed. 37.5 ± 2.7 % (M ± SE) of the tracer was recovered in breath-CO2, and 7.3 ± 1.1 % was directly transferred into milk. About 0.25 % of the tracer was found in milk long-chain polyunsaturated fatty acids. Combining intake and milk data, we estimate that about 65 % of milk ALA is directly derived from maternal diet. Thus, the major portion of milk ALA is directly derived from the diet, but dietary ALA does not seem to contribute much as a precursor to milk n-3 long-chain polyunsaturated fatty acids within the studied time period. PMID:26444910

  16. The Feasibility of Assessing Branched-Chain Amino Acid Metabolism in Cellular Models of Prostate Cancer with Hyperpolarized [1-13C]-Ketoisocaproate

    PubMed Central

    Billingsley, Kelvin L.; Park, Jae Mo; Josan, Sonal; Hurd, Ralph; Mayer, Dirk; Spielman-Sun, Eleanor; Nishimura, Dwight G.; Brooks, James D.; Spielman, Daniel

    2014-01-01

    Recent advancements in the field of hyperpolarized 13C magnetic resonance spectroscopy (MRS) have yielded powerful techniques capable of real-time analysis of metabolic pathways. These non-invasive methods have increasingly shown application in impacting disease diagnosis and have further been employed in mechanistic studies of disease onset and progression. Our goals were to investigate branched-chain aminotransferase (BCAT) activity in prostate cancer with a novel molecular probe, hyperpolarized [1-13C]-2-ketoisocaproate ([1-13C]-KIC), and explore the potential of branched-chain amino acid (BCAA) metabolism to serve as a biomarker. Using traditional spectrophotometric assays, BCAT enzymatic activities were determined in vitro for various sources of prostate cancer (human, transgenic adenocarcinoma of the mouse prostate (TRAMP) mouse and human cell lines). These preliminary studies indicated that low levels of BCAT activity were present in all models of prostate cancer but enzymatic levels are altered significantly in prostate cancer relative to healthy tissue. The MR spectroscopic studies were conducted with two cellular models (PC-3 and DU-145) that exhibited levels of BCAA metabolism comparable to the human disease state. Hyperpolarized [1-13C]-KIC was administered to prostate cancer cell lines, and the conversion of [1-13C]-KIC to the metabolic product, [1-13C]-leucine ([1-13C]-Leu), could be monitored via hyperpolarized 13C MRS. PMID:24907854

  17. Generation of C3- and C2-deuterated L-lactic acid by human erythrocytes exposed to D-[1-13C]glucose, D-[2-13C]glucose and D-[6-13C]glucose in the presence of D2O.

    PubMed

    Malaisse, W J; Biesemans, M; Willem, R

    1994-05-01

    1. The generation of C2- and C3-deuterated L-lactate was monitored by 13C NMR in human erythrocytes exposed to D-[1-13C]glucose, D-[2-13C]glucose or D-[6-13C]glucose and incubated in a medium prepared in D2O. 2. The results suggested that the deuteration of the C1 of D-fructose 6-phosphate in the phosphoglucoisomerase reaction, the deuteration of the C1 of D-glyceraldehyde-3-phosphate in the sequence of reactions catalyzed by triose phosphate isomerase and aldolase and the deuteration of the C3 of pyruvate in the reaction catalyzed by pyruvate kinase were all lower than expected from equilibration with D2O. 3. Moreover, about 40% of the molecules of pyruvate generated by glycolysis apparently underwent deuteration on their C3 during interconversion of the 2-keto acid and L-alanine in the reaction catalyzed by glutamate-pyruvate transaminase. 4. The occurrence of the latter process was also documented in cells exposed to exogenous [3-13C]pyruvate. 5. This methodological approach is proposed to provide a new tool to assess in intact cells the extent of back-and-forth interconversion of selected metabolic intermediates. PMID:8005354

  18. Investigation of amino acid δ 13C signatures in bone collagen to reconstruct human palaeodiets using liquid chromatography-isotope ratio mass spectrometry

    NASA Astrophysics Data System (ADS)

    Choy, Kyungcheol; Smith, Colin I.; Fuller, Benjamin T.; Richards, Michael P.

    2010-11-01

    This research presents the individual amino acid δ 13C values in bone collagen of humans ( n = 9) and animals ( n = 27) from two prehistoric shell midden sites in Korea. We obtained complete baseline separation of 16 of the 18 amino acids found in bone collagen by using liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). The isotopic results reveal that the humans and animals in the two sites had similar patterns in essential amino acids (EAAs) and non-essential amino acids (NEAAs). The EAA and NEAA δ 13C values in humans are intermediate between those in marine and terrestrial animals. However, the threonine δ 13C values in humans and animals measured in this study are more highly enriched than those of other amino acids. At both sites, all amino acids in marine animals are 13C-enriched relative to those of the terrestrial animals. The isotopic evidence suggests that the Tongsamdong human had EAAs and NEAAs from marine food resources, while the Nukdo humans mainly had EAAs from terrestrial food resources but obtained NEAAs from both terrestrial and marine resources. The δ 13C isotopic differences in amino acids between marine and terrestrial animals were the largest for glycine (NEAA) and histidine (EAA) and the smallest for tyrosine (NEAA) and phenylalanine (EAA). In addition, threonine among the EAAs also had a large difference (˜8‰) in δ 13C values between marine and terrestrial animals, and has the potential to be used as an isotopic marker in palaeodietary studies. Threonine δ 13C values were used in conjunction with the established Δ 13C Glycine-phenylalanine values and produced three distinct dietary groups (terrestrial, omnivorous, and marine). In addition, threonine δ 13C values and Δ 13C Serine-phenylalanine values were discovered to separate between two dietary groups (terrestrial vs. marine), and these δ 13C values may provide a potential new indicator for investigating the distinction between marine and terrestrial protein

  19. Mathematical analysis of isotope labeling in the citric acid cycle with applications to 13C NMR studies in perfused rat hearts.

    PubMed

    Chance, E M; Seeholzer, S H; Kobayashi, K; Williamson, J R

    1983-11-25

    Rat hearts have been perfused in vitro with 5 mM glucose and either 5 mM acetate or 1 mM pyruvate to achieve steady state conditions, followed by replacement of the acetate with 90% enriched [2-13C]acetate or pyruvate with 90% enriched [3-13C]pyruvate. The hearts were frozen different times after addition of 13C-substrate and neutralized perchloric acid extracts from three pooled hearts per time point were used to obtain high resolution proton-decoupled 13C NMR spectra at 90.55 MHz. The 13C fractional enrichment of individual carbons of different metabolites was calculated from the area of the resolved resonances after correction for nuclear Overhauser enhancement and saturation effects. A mathematical flux model of the citric acid cycle and ancillary transamination reactions was constructed with the FACSIMILE program, and used to solve unknown flux parameters with constant pool sizes by nonlinear least squares analysis of the approximately 200 simultaneous differential equations required to describe the reactions. With [2-13C] acetate as substrate, resonances and line splittings due to 13C-13C spin coupling of the C-2, C-3, and C-4 carbons of glutamate were well resolved. The half-times to reach maximum 13C enrichment were 2.6 min for glutamate C-4 and 8 min for glutamate C-2 and C-3. From these data, a well determined citric acid cycle flux of 8.3 mumol/g dry weight X min was calculated for an observed oxygen consumption of 31 mumol/g dry weight X min. With [3-13C]pyruvate as substrate, resonances of aspartate C-2 and C-3 and of alanine C-3 were well resolved in addition to those of glutamate C-2, C-3, and C-4. Nonlinear least squares fitting of these data to the model gave nonrandomly distributed residuals for the 13C fractional enrichments of glutamate C-4, suggesting an incomplete model, but a well determined cycle flux of 11.9 mumol/g dry weight X min for an oxygen uptake of 35 mumol/g dry weight X min. Our studies demonstrate the practicality of 13C NMR

  20. Hypermetabolic state in the 7-month-old triple transgenic mouse model of Alzheimer's disease and the effect of lipoic acid: a 13C-NMR study

    PubMed Central

    Sancheti, Harsh; Patil, Ishan; Kanamori, Keiko; Díaz Brinton, Roberta; Zhang, Wei; Lin, Ai-Ling; Cadenas, Enrique

    2014-01-01

    Alzheimer's disease (AD) is characterized by age-dependent biochemical, metabolic, and physiologic changes. These age-dependent changes ultimately converge to impair cognitive functions. This study was carried out to examine the metabolic changes by probing glucose and tricarboxylic acid cycle metabolism in a 7-month-old triple transgenic mouse model of AD (3xTg-AD). The effect of lipoic acid, an insulin-mimetic agent, was also investigated to examine its ability in modulating age-dependent metabolic changes. Seven-month-old 3xTg-AD mice were given intravenous infusion of [1-13C]glucose followed by an ex vivo 13C nuclear magnetic resonance to determine the concentrations of 13C-labeled isotopomers of glutamate, glutamine, aspartate, gamma aminobutyric acid, and N-acetylaspartate. An intravenous infusion of [1-13C]glucose+[1,2-13C]acetate was given for different periods of time to distinguish neuronal and astrocytic metabolism. Enrichments of glutamate, glutamine, and aspartate were calculated after quantifying the total (12C+13C) concentrations by high-performance liquid chromatography. A hypermetabolic state was clearly evident in 7-month-old 3xTg-AD mice in contrast to the hypometabolic state reported earlier in 13-month-old mice. Hypermetabolism was evidenced by prominent increase of 13C labeling and enrichment in the 3xTg-AD mice. Lipoic acid feeding to the hypermetabolic 3xTg-AD mice brought the metabolic parameters to the levels of nonTg mice. PMID:25099753

  1. Hypermetabolic state in the 7-month-old triple transgenic mouse model of Alzheimer's disease and the effect of lipoic acid: a 13C-NMR study.

    PubMed

    Sancheti, Harsh; Patil, Ishan; Kanamori, Keiko; Díaz Brinton, Roberta; Zhang, Wei; Lin, Ai-Ling; Cadenas, Enrique

    2014-11-01

    Alzheimer's disease (AD) is characterized by age-dependent biochemical, metabolic, and physiologic changes. These age-dependent changes ultimately converge to impair cognitive functions. This study was carried out to examine the metabolic changes by probing glucose and tricarboxylic acid cycle metabolism in a 7-month-old triple transgenic mouse model of AD (3xTg-AD). The effect of lipoic acid, an insulin-mimetic agent, was also investigated to examine its ability in modulating age-dependent metabolic changes. Seven-month-old 3xTg-AD mice were given intravenous infusion of [1-(13)C]glucose followed by an ex vivo (13)C nuclear magnetic resonance to determine the concentrations of (13)C-labeled isotopomers of glutamate, glutamine, aspartate, gamma aminobutyric acid, and N-acetylaspartate. An intravenous infusion of [1-(13)C]glucose+[1,2-(13)C]acetate was given for different periods of time to distinguish neuronal and astrocytic metabolism. Enrichments of glutamate, glutamine, and aspartate were calculated after quantifying the total ((12)C+(13)C) concentrations by high-performance liquid chromatography. A hypermetabolic state was clearly evident in 7-month-old 3xTg-AD mice in contrast to the hypometabolic state reported earlier in 13-month-old mice. Hypermetabolism was evidenced by prominent increase of (13)C labeling and enrichment in the 3xTg-AD mice. Lipoic acid feeding to the hypermetabolic 3xTg-AD mice brought the metabolic parameters to the levels of nonTg mice. PMID:25099753

  2. Reversal of metabolic deficits by lipoic acid in a triple transgenic mouse model of Alzheimer's disease: a 13C NMR study.

    PubMed

    Sancheti, Harsh; Kanamori, Keiko; Patil, Ishan; Díaz Brinton, Roberta; Ross, Brian D; Cadenas, Enrique

    2014-02-01

    Alzheimer's disease is an age-related neurodegenerative disease characterized by deterioration of cognition and loss of memory. Several clinical studies have shown Alzheimer's disease to be associated with disturbances in glucose metabolism and the subsequent tricarboxylic acid (TCA) cycle-related metabolites like glutamate (Glu), glutamine (Gln), and N-acetylaspartate (NAA). These metabolites have been viewed as biomarkers by (a) assisting early diagnosis of Alzheimer's disease and (b) evaluating the efficacy of a treatment regimen. In this study, 13-month-old triple transgenic mice (a mouse model of Alzheimer's disease (3xTg-AD)) were given intravenous infusion of [1-(13)C]glucose followed by an ex vivo (13)C NMR to determine the concentrations of (13)C-labeled isotopomers of Glu, Gln, aspartate (Asp), GABA, myo-inositol, and NAA. Total ((12)C+(13)C) Glu, Gln, and Asp were quantified by high-performance liquid chromatography to calculate enrichment. Furthermore, we examined the effects of lipoic acid in modulating these metabolites, based on its previously established insulin mimetic effects. Total (13)C labeling and percent enrichment decreased by ∼50% in the 3xTg-AD mice. This hypometabolism was partially or completely restored by lipoic acid feeding. The ability of lipoic acid to restore glucose metabolism and subsequent TCA cycle-related metabolites further substantiates its role in overcoming the hypometabolic state inherent in early stages of Alzheimer's disease. PMID:24220168

  3. In-Situ 13C-Labeling of Microbial Phospholipid Fatty Acids: Tracing Substrate Assimilation in a Petroleum-Contaminated Aquifer

    NASA Astrophysics Data System (ADS)

    Pombo, S. A.; Schroth, M. H.; Pelz, O.; Zeyer, J.

    2001-12-01

    Stable isotope analysis of phospholipid-derived fatty acids (PLFA) is a novel tool to trace assimilation of organic carbon in microbial communities. The 13C-labeling of biomarker fatty acids allows the identification of specific microbial populations involved in the metabolism of particular substrates, supplemented in 13C-labeled form. The goal of this study was to investigate the feasibility of 13C-labeling of PLFA and produced dissolved inorganic carbon (DIC) in a petroleum hydrocarbon (PHC)-contaminated aquifer during an in-situ experiment. To this end, we performed a single-well "push-pull" test in a monitoring well located in the denitrifying zone of a PHC-contaminated aquifer in Studen, Switzerland. During the experiment, we injected 500 L of site groundwater that was amended with 13C-labeled acetate (50% [2-13C]) and nitrate as reactants, and bromide as conservative tracer. Following the injection, we extracted a total of 1000 L of test solution/groundwater mixture after 4, 23 and 46 h from the same location. Concentrations of anions were measured in samples collected during the extraction. From these data, we computed first order rate coefficients for consumption of acetate (0.70 +/- 0.05 1/d) and nitrate (0.63 +/- 0.08 1/d). In addition, we extracted and identified PLFA, and measured \\delta13C values of PLFA and DIC. After only 4 h of incubation, we detected 13C-enrichment of certain PLFA in suspended biomass of extracted groundwater. After 46 h, we measured enrichments of up to 5000 per mil in certain PLFA (e.g. 16:1ω 7c), and up to 1500 per mil in the produced DIC. Our results demonstrate the feasibility of in-situ 13C-labeling of PLFA and DIC using push-pull tests to determine microbial activities in-situ in a natural ecosystem.

  4. Routing of Fatty Acids from Fresh Grass to Milk Restricts the Validation of Feeding Information Obtained by Measuring (13)C in Milk.

    PubMed

    Auerswald, Karl; Schäufele, Rudi; Bellof, Gerhard

    2015-12-01

    Dairy production systems vary widely in their feeding and livestock-keeping regimens. Both are well-known to affect milk quality and consumer perceptions. Stable isotope analysis has been suggested as an easy-to-apply tool to validate a claimed feeding regimen. Although it is unambiguous that feeding influences the carbon isotope composition (δ(13)C) in milk, it is not clear whether a reported feeding regimen can be verified by measuring δ(13)C in milk without sampling and analyzing the feed. We obtained 671 milk samples from 40 farms distributed over Central Europe to measure δ(13)C and fatty acid composition. Feeding protocols by the farmers in combination with a model based on δ(13)C feed values from the literature were used to predict δ(13)C in feed and subsequently in milk. The model considered dietary contributions of C3 and C4 plants, contribution of concentrates, altitude, seasonal variation in (12/13)CO2, Suess's effect, and diet-milk discrimination. Predicted and measured δ(13)C in milk correlated closely (r(2) = 0.93). Analyzing milk for δ(13)C allowed validation of a reported C4 component with an error of <8% in 95% of all cases. This included the error of the method (measurement and prediction) and the error of the feeding information. However, the error was not random but varied seasonally and correlated with the seasonal variation in long-chain fatty acids. This indicated a bypass of long-chain fatty acids from fresh grass to milk. PMID:26567466

  5. Sensitivity and specificity of an abbreviated 13C-mixed triglyceride breath test for measurement of pancreatic exocrine function

    PubMed Central

    Meier, Viola; Wolfram, Kristina U; Rosien, Ulrich; Layer, Peter

    2014-01-01

    Background A modified 13C-mixed triglyceride breath test (13C -MTGT) detects moderate pancreatic exocrine insufficiency noninvasively and reliably, but it requires prolonged breath sampling (6 hours (hr)). Objective We aimed to investigate whether 13C -MTGT can be abbreviated, to optimize clinical usability. Methods We analyzed the 13C-MTGT of 200 consecutive patients, retrospectively. Cumulative 1–5 hr 13C-exhalation values were compared with the standard parameter (6-hr cumulative 13C-exhalation). We determined the sensitivity and specificity of shortened breath sampling periods, by comparison with the normal values from 10 healthy volunteers, whom also underwent a secretin test to quantitate pancreatic secretion. Moreover, we evaluated the influence of gastric emptying (GE), using a 13C-octanoic acid breath test in a subset (N = 117). Results The 1–5 hr cumulative 13C-exhalation tests correlated highly and significantly with the standard parameter (p < 0.0001). Sensitivity for detection of impaired lipolysis was high (≥77%), but the specificity was low (≥38%) for the early measurements. Both parameters were high after 4 hrs (88% and 94%, respectively) and 5 hrs (98% and 91%, respectively). Multivariate linear correlation analysis confirmed that GE strongly influenced early postprandial 13C-exhalation during the 13C-MTGT. Conclusion Shortening of the 13C -MTGT from 6 to 4 hrs of duration was associated with similar diagnostic accuracy, yet increased clinical usability. The influence of GE on early postprandial results of the 13C-MTGT precluded further abbreviation of the test. PMID:25083286

  6. The effect of dietary amino acid abundance and isotopic composition on the growth rate, metabolism and tissue δ13C of rainbow trout.

    PubMed

    Gaye-Siessegger, Julia; McCullagh, James S O; Focken, Ulfert

    2011-06-28

    The aim of the present study was to test whether the dietary non-essential/conditionally essential amino acid composition has an effect on growth and protein utilisation and on δ13C of individual amino acids in rainbow trout (Oncorhynchus mykiss). Trout were reared on six purified diets containing only synthetic amino acids in place of protein. Diet 1 mimicked the amino acid composition of fishmeal, in diet 2, cysteine (Cys), glycine (Gly), proline (Pro) and tyrosine (Tyr) were isonitrogenously replaced by their precursor amino acids serine (Ser), glutamic acid (Glu) and phenylalanine (Phe), and in diet 3, alanine (Ala), asparagine and aspartate, Cys, Gly, Pro, Ser and Tyr were isonitrogenously replaced by Glu. Diets 4, 5 and 6 resembled diets 1, 2 and 3 except that Glu contained 0·1 % 13C-enriched Glu. A control group was reared on a fishmeal-based diet. A total of forty-two trout (4·7 (sd 0·57) g) were fed one of the diets at a level of 3·5 % body mass for 10 weeks in a flow-through system. Dietary non-essential amino acid composition significantly influenced protein gain (P < 0·025) and δ13C of Ala, arginine (Arg), Gly, histidine (His), Phe and Tyr. Non-enriched Glu was predominantly found in trout fed 13C-enriched Glu, which is consistent with the fact that Glu has been shown to be used extensively in the gut as an energy source but is less consistent with the enrichment of Pro in fish fed diet 6 compared with fish fed diet 3. Further research is required to better understand the mechanisms that lead to the alteration of amino acid δ13C between diet and body tissues. PMID:21418707

  7. A study of the experimental and theoretical infrared, Raman, 1H and 13C NMR spectra of the biochemicals valeric and valproic acids

    NASA Astrophysics Data System (ADS)

    Badawi, Hassan M.; Förner, Wolfgang; Ali, Shaikh A.

    2014-10-01

    The structural stability, vibrational, 1H and 13C NMR spectra of valeric and valproic acids were investigated by the B3LYP calculations with the 6-311G** basis set. Valeric acid is predicted to exist predominantly in the planar cis form (80% abundance). Valproic acid is predicted to have an equilibrium mixture of 68% gauche-1 and 32% gauche-2 structures at 298.15 K. The spectral feature of the Osbnd H stretching mode in the infrared spectra of both acids suggests the presence of strong H-bonding in the condensed phase of valeric acid and weak H-bonding in the case of valproic acid. The harmonic and anharmonic vibrational wavenumbers were computed at the B3LYP level of theory and tentative vibrational assignments were provided on the basis of combined theoretical and experimental infrared and Raman data of the molecules. Not all of the calculated anharmonic wavenumbers showed a consistent trend with the observed wavenumbers. The 1H and 13C NMR spectra of both acids were interpreted by experimental and DFT calculated chemical shifts of the two acids. The RMSD between experimental and theoretical 1H and 13C chemical shifts for valeric acid is 1.8 and 3.8 ppm, whereas for valproic acid, it is 1.4 and 4.5 ppm, respectively.

  8. Can 13C stable isotope analysis uncover essential amino acid provisioning by termite-associated gut microbes?

    PubMed Central

    Jones, Susan C.; Sabree, Zakee L.

    2015-01-01

    Gut-associated microbes of insects are postulated to provide a variety of nutritional functions including provisioning essential amino acids (EAAs). Demonstrations of EAA provisioning in insect-gut microbial systems, nonetheless, are scant. In this study, we investigated whether the eastern subterranean termite Reticulitermes flavipes sourced EAAs from its gut-associated microbiota. δ13CEAA data from termite carcass, termite gut filtrate and dietary (wood) samples were determined following 13C stable isotope analysis. Termite carcass samples (−27.0 ± 0.4‰, mean ± s.e.) were significantly different from termite gut filtrate samples (−27.53 ± 0.5‰), but not the wood diet (−26.0 ± 0.5‰) (F(2,64) = 6, P < 0.0052). δ13CEAA-offsets between termite samples and diet suggested possible non-dietary EAA input. Predictive modeling identified gut-associated bacteria and fungi, respectively as potential major and minor sources of EAAs in both termite carcass and gut filtrate samples, based on δ13CEAA data of four and three EAAs from representative bacteria, fungi and plant data. The wood diet, however, was classified as fungal rather than plant in origin by the model. This is attributed to fungal infestation of the wood diet in the termite colony. This lowers the confidence with which gut microbes (bacteria and fungi) can be attributed with being the source of EAA input to the termite host. Despite this limitation, this study provides tentative data in support of hypothesized EAA provisioning by gut microbes, and also a baseline/framework upon which further work can be carried out to definitively verify this function. PMID:26336647

  9. A citric acid solution is an optimal test drink in the 13C-urea breath test for the diagnosis of Helicobacter pylori infection.

    PubMed Central

    Domínguez-Muñoz, J E; Leodolter, A; Sauerbruch, T; Malfertheiner, P

    1997-01-01

    BACKGROUND: The 13C-urea breath test (13C-UBT) is a simple, non-invasive and reliable test for the diagnosis of Helicobacter pylori infection. The duration of the test, the timing of breath sampling, and the accuracy of the method vary according to the test meal used. AIM: To identify the optimal test meal or drink for rapid and accurate performance of the 13C-UBT for the detection of H pylori infection. PATIENTS: Eighty patients with dyspeptic symptoms were included. Of these, 48 patients had a positive H pylori status and 32 a negative one according to the results of the rapid urease test, histological examination, and culture. METHODS: A 13C-UBT was performed after an overnight fast, on three consecutive days. On each study day a different test meal or drink was given (0.1 N citric acid solution, a standard semiliquid meal, or a semiliquid fatty meal) 10 minutes before giving 75 mg 13C-urea. Breath samples were collected at 0, 15, 30, 45, and 60 minutes, and analysed by isotype ratio mass spectrometry. Results were expressed as delta (delta) and considered as positive for H pylori if the highest delta (peak) was greater than 4.0. RESULTS: The delta peak obtained with the citric acid drink in H pylori positive subjects (24.1 (SEM 1.5)) was significantly higher than that obtained with any of the semiliquid meals (13.3 (SEM 1.1) and 17.1 (SEM 1.0) respectively, p < 0.001). Furthermore, this delta peak was obtained earlier with the citric acid drink (30 (SEM 2) minutes) than with the other two meals tests (53 (SEM 2) min and 45 (SEM 2) min, p < 0.001). The sensitivity of the 13C-UBT for the diagnosis of H pylori infection was 96-100% with all three test meals. This high sensitivity was, however, obtained from 15 minutes by giving citric acid as the test drink, from 45 minutes by giving a semiliquid fatty meal, and at 60 minutes by giving the semiliquid standard meal. The specificity was 100% for all test meals. Citric acid is inexpensive and palatable to patients

  10. 13C Nuclear Magnetic Resonance and Electron Paramagnetic Spectroscopic Comparison of Hydrophobic Acid, Transphilic Acid, and Reverse Osmosis May 2012 Isolates of Organic Matter from the Suwannee River

    PubMed Central

    Nwosu, Ugwumsinachi G.; Cook, Robert L.

    2015-01-01

    Abstract Dissolved organic matter (DOM) is found in most natural waters at concentrations low enough to make DOM isolation methodologies critical to full analytical characterization and preservation. During the last few decades, two major protocols have been developed for the extraction of DOM isolates from natural waters. These methods utilize XAD resins and reverse osmosis (RO). In this work, the hydrophobic acid (May 2012 HPOA) and transphilic acid (May 2012 TPIA) isolates from XAD-8 and XAD-4 resins, respectively, were compared with the RO (May 2012 RO) natural organic matter isolate of the Suwannee River water using 13C nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopies. 13C NMR analysis showed that the May 2012 RO isolate could be viewed as a hybrid of the more hydrophobic May 2012 HPOA isolate and more hydrophilic May 2012 TPIA isolate. The May 2012 HPOA isolate is shown to be higher in alkyl and aromatic moieties, while the May 2012 TPIA isolate is higher in O-alkyl moieties. EPR analysis revealed that the May 2012 TPIA and, in particular, May 2012 HPOA isolates had higher radical concentrations than the May 2012 RO isolate. It is postulated that some of the radical concentrations came from the use of base during the isolation procedures, especially in the XAD method. PMID:25565761

  11. (13)C/(12)C isotope ratios of organic acids, glucose and fructose determined by HPLC-co-IRMS for lemon juices authenticity.

    PubMed

    Guyon, Francois; Auberger, Pauline; Gaillard, Laetita; Loublanches, Caroline; Viateau, Maryse; Sabathié, Nathalie; Salagoïty, Marie-Hélène; Médina, Bernard

    2014-03-01

    High performance liquid chromatography linked to isotope ratio mass spectrometry via an interface allowing the chemical oxidation of organic matter (HPLC-co-IRMS) was used to simultaneously determine carbon 13 isotope ratio (δ(13)C) of organic acids, glucose and fructose in lime and lemon juices. Because of the significant difference between organic acids and sugars concentrations, the experimental protocol was optimised by applying a "current jump" to the IRMS device. The filament current is increased of 300μA during elution in order to enhance IRMS sensitivity. Then, analysis were performed on 35 lemon and lime fruits from various geographical origins and squeezed in the laboratory. An overall average δ(13)C values of -25.40±1.62‰, -23.83±1.82‰ and -25.67±1.72‰ is found for organic acids mixture mainly made up of citric acid, glucose and fructose, respectively. These authentic samples allowed the definition of a confidence domain to which have been confronted 30 commercial juices (24 "pure juices" and 6 coming from concentrate). Among these 30 samples, 10 present δ(13)C values outside the defined range revealing an added "C4" type organic acids or sugars, addition not specified on the label that is not in agreement with EU regulation. PMID:24176310

  12. Mechanism of formation of humus coatings on mineral surfaces 3. Composition of adsorbed organic acids from compost leachate on alumina by solid-state 13C NMR

    USGS Publications Warehouse

    Wershaw, R. L.; Llaguno, E.C.; Leenheer, J.A.

    1996-01-01

    The adsorption of compost leachate DOC on alumina is used as a model for elucidation of the mechanism of formation of natural organic coatings on hydrous metal oxide surfaces in soils and sediments. Compost leachate DOC is composed mainly of organic acid molecules. The solid-state 13C NMR spectra of these organic acids indicate that they are very similar in composition to aquatic humic substances. Changes in the solid-state 13C NMR spectra of compost leachate DOC fractions adsorbed on alumina indicate that the DOC molecules are most likely adsorbed on metal oxide surfaces through a combination of polar and hydrophobic interaction mechanisms. This combination of polar and hydrophobic mechanism leads to the formation of bilayer coatings of the leachate molecules on the oxide surfaces.

  13. Amino-acid selective experiments on uniformly 13C and 15N labeled proteins by MAS NMR: Filtering of lysines and arginines

    NASA Astrophysics Data System (ADS)

    Jehle, Stefan; Rehbein, Kristina; Diehl, Anne; van Rossum, Barth-Jan

    2006-12-01

    Amino-acid selective magic-angle spinning (MAS) NMR experiments can aid the assignment of ambiguous cross-peaks in crowded spectra of solid proteins. In particular for larger proteins, data analysis can be hindered by severe resonance overlap. In such cases, filtering techniques may provide a good alternative to site-specific spin-labeling to obtain unambiguous assignments that can serve as starting points in the assignment procedure. In this paper we present a simple pulse sequence that allows selective excitation of arginine and lysine residues. To achieve this, we make use of a combination of specific cross-polarization for selective excitation [M. Baldus, A.T. Petkova, J. Herzfeld, R.G. Griffin, Cross polarization in the tilted frame: assignment and spectral simplification in heteronuclear spin systems, Mol. Phys. 95 (1998) 1197-1207.] and spin diffusion for transfer along the amino-acid side-chain. The selectivity of the filter is demonstrated with the excitation of lysine and arginine side-chain resonances in a uniformly 13C and 15N labeled protein preparation of the α-spectrin SH3 domain. It is shown that the filter can be applied as a building block in a 13C- 13C lysine-only correlation experiment.

  14. Sensitive, Efficient Quantitation of 13C-Enriched Nucleic Acids via Ultrahigh-Performance Liquid Chromatography–Tandem Mass Spectrometry for Applications in Stable Isotope Probing

    PubMed Central

    Wilhelm, Roland; Szeitz, András; Klassen, Tara L.

    2014-01-01

    Stable isotope probing (SIP) of nucleic acids is a powerful tool for studying the functional traits of microbial populations within complex communities, but SIP involves a number of technical challenges. Many of the difficulties in DNA-SIP and RNA-SIP experiments can be effectively overcome with an efficient, sensitive method for quantitating the isotopic enrichment of nucleic acids. Here, we present a sensitive method for quantitating 13C enrichment of nucleic acids, requiring a few nanograms of sample, and we demonstrate its utility in typical DNA-SIP and RNA-SIP experiments. All five nucleobases (adenine, guanine, cytosine, thymine, and uracil) were separated and detected by using ultrahigh-performance liquid chromatography–tandem mass spectrometry. We detected all isotopic species in samples with as low as 1.5 atom% 13C above natural abundance, using 1-ng loadings. Quantitation was used to characterize the isotopic enrichment kinetics of cellulose- and lignin-based microcosm experiments and to optimize the recovery of enriched nucleic acids. Application of our method will minimize the quantity of expensive isotopically labeled substrates required and reduce the risk of failed experiments due to insufficient recovery of labeled nucleic acids for sequencing library preparation. PMID:25217022

  15. Medium-chain fatty acid binding to albumin and transfer to phospholipid bilayers

    SciTech Connect

    Hamilton, J.A. )

    1989-04-01

    Temperature-dependent (5-42{degree}C) {sup 13}C NMR spectra of albumin complexes with 90% isotopically substituted (1-{sup 13}C)octanoic or (1-{sup 13}C)decanoic acids showed a single peak at >30{degree}C but three peaks at lower temperatures. The chemical-shift differences result from different ionic and/or hydrogen-bonding interactions between amino acid side chains and the fatty acid carboxyl carbon. Rapid exchange of fatty acid among binding sites obscures these sites at temperatures >30{degree}C. Rate constants for exchange at 33{degree}C were 350 sec{sup {minus}1} for octanoate and 20 sec {sup {minus}1} for decanoate. Temperature-dependent data for octanoate showed an activation energy of 2 kcal/mol for exchange. Spectra of albumin complexes with the 12-carbon saturated fatty acid, lauric acid, had several narrow laurate carboxyl peaks at 35{degree}C, indicating longer lifetimes in the different binding sites. Fatty acid exchange between albumin and model membranes (phosphatidylcholine bilayers) occurred on a time scale comparable to that for exchange among albumin binding sites, following the order octanoate > decanoate > laurate. The equilibrium distribution of fatty acid between lipid bilayers and protein was measured directly from NMR spectra. Decreasing pH increased the relative affinity of fatty acid for the lipid bilayer. The results predict that the relative affinity of octanoic acid for albumin and membranes will be similar to that of long-chain fatty acids, but the rate of equilibration will be {approx} 10{sup 4} faster for octanoic acid.

  16. 1H, 15N and 13C resonance assignments of light organ-associated fatty acid-binding protein of Taiwanese fireflies.

    PubMed

    Tseng, Kai-Li; Lee, Yi-Zong; Chen, Yun-Ru; Lyu, Ping-Chiang

    2016-04-01

    Fatty acid-binding proteins (FABPs) are a family of proteins that modulate the transfer of various fatty acids in the cytosol and constitute a significant portion in many energy-consuming cells. The ligand binding properties and specific functions of a particular type of FABP seem to be diverse and depend on the respective binding cavity as well as the cell type from which this protein is derived. Previously, a novel FABP (lcFABP; lc: Luciola cerata) was identified in the light organ of Taiwanese fireflies. The lcFABP was proved to possess fatty acids binding capabilities, especially for fatty acids of length C14-C18. However, the structural details are unknown, and the structure-function relationship has remained to be further investigated. In this study, we finished the (1)H, (15)N and (13)C chemical shift assignments of (15)N/(13)C-enriched lcFABP by solution NMR spectroscopy. In addition, the secondary structure distribution was revealed based on the backbone N, H, Cα, Hα, C and side chain Cβ assignments. These results can provide the basis for further structural exploration of lcFABP. PMID:26373428

  17. Short hydrogen bonds in salts of dicarboxylic acids; structural correlations from solid-state 13C and 2H NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kalsbeek, Nicoline; Schaumburg, Kjeld; Larsen, Sine

    1993-10-01

    Solid-state 13C and 2H NMR spectra are found to very suitable for characterizing the short Osbnd H...O hydrogen bonds observed in acid salts of dicarboxylic acids. The majority of the investigated compounds are acid salts of malonic, succinic and tartaric acid with monovalent cations derived from alkali metals and small aliphatic amines. They include systems with symmetric and asymmetric hydrogen bonds. Accurate structural information about their geometry is available from low-temperature X-ray diffraction data. The 13C chemical shifts of the C atoms in the different carboxy groups display a linear variation with the absolute difference between the two Csbnd O bond lengths. Theoretical ab initio calculations for model systems showed that the nuclear quadrupole coupling constant NQCC for 2H increases with increasing asymmetry of the hydrogen-bonded system. NQCC values for 2H in the short symmetric hydrogen-bonded systems are in the range 53-59 kHz compared with the larger values of up to 166kHz found in systems with longer asymmetric hydrogen bonds. The 2H NQCC values display a perfect linear dependence on the asymmetry of the hydrogen bond. 2H NQCC decreases with decreasing temperature in the symmetric hydrogen bonds showing that the corresponding potential has a single well.

  18. How closely do the delta(13)C values of Crassulacean Acid metabolism plants reflect the proportion of CO(2) fixed during day and night?

    PubMed

    Winter, Klaus; Holtum, Joseph A M

    2002-08-01

    The extent to which Crassulacean acid metabolism (CAM) plant delta(13)C values provide an index of the proportions of CO(2) fixed during daytime and nighttime was assessed. Shoots of seven CAM species (Aloe vera, Hylocereus monocanthus, Kalanchoe beharensis, Kalanchoe daigremontiana, Kalanchoe pinnata, Vanilla pauciflora, and Xerosicyos danguyi) and two C(3) species (teak [Tectona grandis] and Clusia sp.) were grown in a cuvette, and net CO(2) exchange was monitored for up to 51 d. In species exhibiting net dark CO(2) fixation, between 14% and 73.3% of the carbon gain occurred in the dark. delta(13)C values of tissues formed inside the cuvette ranged between -28.7 per thousand and -11.6 per thousand, and correlated linearly with the percentages of carbon gained in the light and in the dark. The delta(13)C values for new biomass obtained solely during the dark and light were estimated as -8.7 per thousand and -26.9 per thousand, respectively. For each 10% contribution of dark CO(2) fixation integrated over the entire experiment, the delta(13)C content of the tissue was, thus, approximately 1.8 per thousand less negative. Extrapolation of the observations to plants previously surveyed under natural conditions suggests that the most commonly expressed version of CAM in the field, "the typical CAM plant," involves plants that gain about 71% to 77% of their carbon by dark fixation, and that the isotopic signals of plants that obtain one-third or less of their carbon in the dark may be confused with C(3) plants when identified on the basis of carbon isotope content alone. PMID:12177497

  19. Experimental (FT-IR, FT-Raman, UV-Vis, 1H and 13C NMR) and computational (density functional theory) studies on 3-bromophenylboronic acid

    NASA Astrophysics Data System (ADS)

    Karabacak, M.; Kose, E.; Atac, A.; Sas, E. B.; Asiri, A. M.; Kurt, M.

    2014-11-01

    Structurally, boronic acids are trivalent boron-containing organic compounds that possess one alkyl substituent (i.e., C-Br bond) and two hydroxyl groups to fill the remaining valences on the boron atom. We studied 3-bromophenylboronic acid (3BrPBA); a derivative of boronic acid. This study includes the experimental (FT-IR, FT-Raman, 1H and 13C NMR, UV-Vis) techniques and theoretical (DFT-density functional theory) calculations. The experimental data are recorded, FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-10 cm-1) in the solid phase. 1H and 13C NMR spectra are recorded in DMSO solution. UV-Vis spectrum is recorded in the range of 200-400 nm for each solution (in ethanol and water). The theoretical calculations are computed DFT/B3LYP/6-311++G(d,p) basis set. The optimum geometry is also obtained from inside for possible four conformers using according to position of hydrogen atoms after the scan coordinate of these structures. The fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and parallel quantum solutions (PQS) program. 1H and 13C NMR chemical shifts are racked on by using the gauge-invariant atomic orbital (GIAO) method. The time-dependent density functional theory (TD-DFT) is used to find HOMO and LUMO energies, excitation energies, oscillator strengths. The density of state of the studied molecule is investigated as total and partial density of state (TDOS and PDOS) and overlap population density of state (OPDOS or COOP) diagrams have been presented. Besides, frontier molecular orbitals (FMOs), molecular electrostatic potential surface (MEPs) and thermodynamic properties are performed. At the end of this work, the results are ensured beneficial for the literature contribution.

  20. [13C]-Specific labeling of 8-2' linked (-)-cis-blechnic, (-)-trans-blechnic and (-)-brainic acids in the fern Blechnum spicant

    NASA Technical Reports Server (NTRS)

    Davin, Laurence B.; Wang, Chang-Zeng; Helms, Gregory L.; Lewis, Norman G.

    2003-01-01

    In vivo administration experiments using stable (13C) and radio (14C) labeled precursors established that the optically active 8-2' linked lignans, (-)-cis-blechnic, (-)-trans-blechnic and (-)-trans-brainic acids, were directly derived from L-phenylalanine, cinnamate, and p-coumarate but not either from tyrosine or acetate. The radiochemical time course data suggest that the initial coupling product is (-)-cis-blechnic acid, which is then apparently converted into both (-)-trans-blechnic and (-)-trans-brainic acids in vivo. These findings provide additional evidence for vascular plant proteins engendering distinct but specific phenolic radical-radical coupling modes, i.e., for full control over phenylpropanoid coupling in vivo, whether stereoselective or regiospecific.

  1. /sup 13/C NMR study of effects of fasting and diabetes on the metabolism of pyruvate in the tricarboxylic acid cycle and of the utilization of pyruvate and ethanol in lipogenesis in perfused rat liver

    SciTech Connect

    Cohen, S.M.

    1987-01-27

    /sup 13/C NMR has been used to study the competition of pyruvate dehydrogenase with pyruvate carboxylase for entry of pyruvate into the tricarboxylic acid (TCA) cycle in perfused liver from streptozotocin-diabetic and normal donor rats. The relative proportion of pyruvate entering the TCA cycle by these two routes was estimated from the /sup 13/C enrichments at the individual carbons of glutamate when (3-/sup 13/C)alanine was the only exogenous substrate present. In this way, the proportion of pyruvate entering by the pyruvate dehydrogenase route relative to the pyruvate carboxylase route was determined to be 1:1.2 +/- 0.1 in liver from fed controls, 1:7.7 +/- 2 in liver from 24-fasted controls, and 1:2.6 +/- 0.3 in diabetic liver. Pursuant to this observation that conversion of pyruvate to acetyl coenzyme A (acetyl-CoA) was greatest in perfused liver from fed controls, the incorporation of /sup 13/C label into fatty acids was monitored in this liver preparation. With the exception of the repeating methylene carbons, fatty acyl carbons labeled by (1-/sup 13/C)acetyl-CoA (from (2-/sup 13/C)pyruvate) gave rise to resonances distinguishable on the basis of chemical shift from those observed when label was introduced by (3-/sup 13/C)alanine plus (2-/sup 13/C)ethanol, which are converted to (2-/sup 13/C)acetyl-CoA. Thus, measurement of /sup 13/C enrichment at several specific sites in the fatty acyl chains in time-resolved spectra of perfused liver offers a novel way of monitoring the kinetics of the biosynthesis of fatty acids. In addition to obtaining the rate of lipogenesis, it was possible to distinguish the contributions of chain elongation from those of the de novo synthesis pathway and to estimate the average chain length of the /sup 13/C-labeled fatty acids produced.

  2. Low Mass MS/MS Fragments of Protonated Amino Acids Used for Distinction of Their 13C- Isotopomers in Metabolic Studies

    NASA Astrophysics Data System (ADS)

    Ma, Xin; Dagan, Shai; Somogyi, Árpád; Wysocki, Vicki H.; Scaraffia, Patricia Y.

    2013-04-01

    Glu, Gln, Pro, and Ala are the main amino acids involved in ammonia detoxification in mosquitoes. In order to develop a tandem mass spectrometry method (MS2) to monitor each carbon of the above isotopically-labeled 13C-amino acids for metabolic studies, the compositions and origins of atoms in fragments of the protonated amino acid should be first elucidated. Thus, various electrospray (ESI)-based MS2 tools were employed to study the fragmentation of these unlabeled and isotopically-labeled amino acids and better understand their dissociation pathways. A broad range of fragments, including previously-undescribed low m/z fragments was revealed. The formulae of the fragments (from m/z 130 down to m/z 27) were confirmed by their accurate masses. The structures and conformations of the larger fragments of Glu were also explored by ion mobility mass spectrometry (IM-MS) and gas-phase hydrogen/deuterium exchange (HDX) experiments. It was found that some low m/z fragments ( m/z 27-30) are common to Glu, Gln, Pro, and Ala. The origins of carbons in these small fragments are discussed and additional collision induced dissociation (CID) MS2 fragmentation pathways are proposed for them. It was also found that small fragments (≤ m/z 84) of protonated, methylated Glu, and methylated Gln are the same as those of the underivatized Glu and Gln. Taken together, the new approach of utilizing low m/z fragments can be applied to distinguish, identify, and quantify 13C-amino acids labeled at various positions, either in the backbone or side chain.

  3. Chemical weathering and the role of sulfuric and nitric acids in carbonate weathering: Isotopes (13C, 15N, 34S, and 18O) and chemical constraints

    NASA Astrophysics Data System (ADS)

    Li, Cai; Ji, Hongbing

    2016-05-01

    Multiple isotopes (13C-DIC, 34S and 18O-SO42-, 15N and 18O-NO3-) and water chemistry were used to evaluate weathering rates and associated CO2 consumption by carbonic acid and strong acids (H2SO4 and HNO3) in a typical karst watershed (Wujiang River, Southwest China). The dual sulfate isotopes indicate that sulfate is mainly derived from sulfide oxidation in coal stratum and sulfide-containing minerals, and dual nitrate isotopes indicate that nitrate is mainly derived from soil N and nitrification. The correlation between isotopic compositions and water chemistry suggests that sulfuric and nitric acids, in addition to carbonic acid, are involved in carbonate weathering. The silicate and carbonate weathering rates are 7.2 t km-2 yr-1 and 76 t km-2 yr-1, respectively. In comparison with carbonate weathering rates (43 t km-2 yr-1) by carbonic acid alone, the subsequent increase in rates indicates significant enhancement of weathering when combined with sulfuric and nitric acids. Therefore, the role of sulfuric and nitric acids in the rock weathering should be considered in the global carbon cycle.

  4. 2H NMR and 13C-IRMS analyses of acetic acid from vinegar, 18O-IRMS analysis of water in vinegar: international collaborative study report.

    PubMed

    Thomas, Freddy; Jamin, Eric

    2009-09-01

    An international collaborative study of isotopic methods applied to control the authenticity of vinegar was organized in order to support the recognition of these procedures as official methods. The determination of the 2H/1H ratio of the methyl site of acetic acid by SNIF-NMR (site-specific natural isotopic fractionation-nuclear magnetic resonance) and the determination of the 13C/12C ratio, by IRMS (isotope ratio mass spectrometry) provide complementary information to characterize the botanical origin of acetic acid and to detect adulterations of vinegar using synthetic acetic acid. Both methods use the same initial steps to recover pure acetic acid from vinegar. In the case of wine vinegar, the determination of the 18O/16O ratio of water by IRMS allows to differentiate wine vinegar from vinegars made from dried grapes. The same set of vinegar samples was used to validate these three determinations. The precision parameters of the method for measuring delta13C (carbon isotopic deviation) were found to be similar to the values previously obtained for similar methods applied to wine ethanol or sugars extracted from fruit juices: the average repeatability (r) was 0.45 per thousand, and the average reproducibility (R) was 0.91 per thousand. As expected from previous in-house study of the uncertainties, the precision parameters of the method for measuring the 2H/1H ratio of the methyl site were found to be slightly higher than the values previously obtained for similar methods applied to wine ethanol or fermentation ethanol in fruit juices: the average repeatability was 1.34 ppm, and the average reproducibility was 1.62 ppm. This precision is still significantly smaller than the differences between various acetic acid sources (delta13C and delta18O) and allows a satisfactory discrimination of vinegar types. The precision parameters of the method for measuring delta18O were found to be similar to the values previously obtained for other methods applied to wine and

  5. New organic single crystal of (benzylthio)acetic acid: Synthesis, crystal structure, spectroscopic (ATR-FTIR, 1H and 13C NMR) and thermal characterization

    NASA Astrophysics Data System (ADS)

    Sienkiewicz-Gromiuk, Justyna; Tarasiuk, Bogdan; Mazur, Liliana

    2016-04-01

    (Benzylthio)acetic acid (Hbta) was synthesized with 78% yield from benzyl chloride and thiourea as substrates. Well-shaped crystals of Hbta were grown by slow solvent evaporation technique from pure methanol. The compound was investigated by single-crystal X-ray and powder diffraction techniques and was also characterized by other analytical methods, like ATR-FTIR, 1H and 13C NMR and TG/DSC. The acid molecule adopts bent conformation in the solid state. The crystal structure of Hbta is stabilized by numerous intermolecular interactions, including O-H···O, C-H···O, C-H···S and C-H···π contacts. Thermal decomposition of the obtained material takes place above 150 °C.

  6. A study of structure and dynamics of poly(aspartic acid) sodium/poly(vinyl alcohol) blends by 13C CP/MAS NMR

    NASA Astrophysics Data System (ADS)

    Wang, P.; Ando, I.

    1999-09-01

    Solid state 13C CP/MAS NMR measurements have been carried out on poly(aspartic acid) sodium (PAANa)/poly(vinyl alcohol) (PVA) blends over a wide range of temperatures. From these experimental results, it is found that the main-chain conformations of PAANa in PAANa/PVA blends take the α-helix form over a wide range of blend ratios, and, in contrast, the conformation and dynamics of the side chains of PAANa are strongly influenced by the formation of an intermolecular hydrogen bond between the carboxyl group of the side chains and the hydroxyl group of PVA. The behavior of the proton spin-lattice relaxation times in the rotating frame ( T1 ρ(H)) and the laboratory frame ( T1(H)) indicates that when the blend ratio of PAANa and PVA is 1:1, they are miscible.

  7. 13C urea breath test (UBT) in the diagnosis of Helicobacter pylori: why does it work better with acid test meals?

    PubMed Central

    Pantoflickova, D; Scott, D R; Sachs, G; Dorta, G; Blum, A L

    2003-01-01

    Background: Acid test meals may improve the accuracy of the 13C urea breath test (UBT). This has been attributed to changes in gastric emptying rather than to the effects of gastric pH on Helicobacter pylori urease. Aims: To determine whether enhancement of 13CO2 excretion in the UBT in H pylori infected volunteers by acidification of a test meal is due to a delay in gastric emptying. Methods: Urease activity in vitro was measured in intact bacteria and in bacterial homogenates. Urease activity in vivo was assessed by means of the UBT. Eleven H pylori infected subjects underwent UBTs with neutral Ensure (pH 7.0), acidified Ensure (pH 3.0), and apple juice (pH 3.0). Gastric emptying was assessed by 13C sodium acetate breath test. Results: From pH 7 to pH 3, the in vitro urease activity of intact bacteria increased sixfold. In contrast, urease activity of bacterial homogenates was inactivated by low pH. In vivo, urease activity, as measured by the UBT 20 minutes after meal ingestion, was higher with apple juice (δ 13CO2=21.1; p=0.03) and acidified Ensure (δ 13CO2=25.5; p=0.01) than with neutral Ensure (δ 13CO2=12.5). Gastric emptying was faster with apple juice (Tmax=36.7 (8) minutes) but not with acidified Ensure (Tmax=63.3 (5) minutes; p=0.06) than with neutral Ensure (Tmax=65.0 (3) minutes; p=0.04). Conclusions: The higher UBT found with acidified compared with neutral test meals was independent of the emptying rates of the test meals but may have been due to medium acidity dependent activation of intra-bacterial urease in intact H pylori. PMID:12801946

  8. Studies on the biodegradation of fosfomycin: synthesis of 13C-labeled intermediates, feeding experiments with Rhizobium huakuii PMY1, and isolation of labeled amino acids from cell mass by HPLC.

    PubMed

    McGrath, John W; Hammerschmidt, Friedrich; Kählig, Hanspeter; Wuggenig, Frank; Lamprecht, Günther; Quinn, John P

    2011-11-18

    Racemic (1R*,2R*)-1,2-dihydroxy-[1-(13)C(1)]propylphosphonic acid and 1-hydroxy-[1-(13)C(1)]acetone were synthesized and fed to R. huakuii PMY1. Alanine and a mixture of valine and methionine were isolated as their N-acetyl derivatives from the cell hydrolysate by reversed-phase HPLC and analyzed by NMR spectroscopy. It was found that the carbon atoms of the respective carboxyl groups were highly (13)C-labeled (up to 65 %). Hydroxyacetone is therefore considered an obligatory intermediate of the biodegradation of fosfomycin by R. huakuii PMY1. PMID:22012897

  9. /sup 18/O isotope effect in /sup 13/C nuclear magnetic resonance spectroscopy. Part 9. Hydrolysis of benzyl phosphate by phosphatase enzymes and in acidic aqueous solutions

    SciTech Connect

    Parente, J.E.; Risley, J.M.; Van Etten, R.L.

    1984-12-26

    The /sup 18/O isotope-induced shifts in /sup 13/C and /sup 31/P nuclear magnetic resonance (NMR) spectroscopy were used to establish the position of bond cleavage in the phosphatase-catalyzed and acid-catalyzed hydrolysis reactions of benzyl phosphate. The application of the /sup 18/O-isotope effect in NMR spectroscopy affords a continuous, nondestructive assay method for following the kinetics and position of bond cleavage in the hydrolytic process. The technique provides advantages over most discontinuous methods in which the reaction components must be isolated and converted to volatile derivatives prior to analysis. In the present study, (..cap alpha..-/sup 13/C,ester-/sup 18/O)benzyl phosphate and (ester-/sup 18/O)benzyl phosphate were synthesized for use in enzymatic and nonenzymatic studies. Hydrolysis reactions catalyzed by the alkaline phosphatase from E. coli and by the acid phosphatases isolated from human prostate and human liver were all accompanied by cleavage of the substrate phosphorus-oxygen bond consistent with previously postulated mechanisms involving covalent phosphoenzyme intermediates. An extensive study of the acid-catalyzed hydrolysis of benzyl phosphate at 75/sup 0/C revealed that the site of bond cleavage is dependent on pH. At pH less than or equal to 1.3, the hydrolysis proceeds with C-O bond cleavage; at 1.3 < pH < 2.0, there is a mixture of C-O and P-O bond scission, the latter progressively predominating as the pH is raised; at pH greater than or equal to 2.0, the hydrolysis proceeds with exclusive P-O bond scission. (S)-(+)-(..cap alpha..-/sup 2/H)Benzyl phosphate was also synthesized. Hydrolysis of this chiral benzyl derivative demonstrated that the acid-catalyzed C-O bond scission of benzyl phosphate proceeds by an A-1 (S/sub N/1) mechanism with 70% racemization and 30% inversion at carbon. 37 references, 4 figures, 2 tables.

  10. Ascorbic acid prolongs the viability and stability of isolated perfused lungs: A mechanistic study using 31P and hyperpolarized 13C nuclear magnetic resonance.

    PubMed

    Shaghaghi, Hoora; Kadlecek, Stephen; Siddiqui, Sarmad; Pourfathi, Mehrdad; Hamedani, Hooman; Clapp, Justin; Profka, Harrilla; Rizi, Rahim

    2015-12-01

    Ex vivo lung perfusion (EVLP) has recently shown promise as a means of more accurately gauging the health of lung grafts and improving graft performance post-transplant. However, reperfusion of ischemic lung promotes the depletion of high-energy compounds and a progressive loss of normal mitochondrial function, and it remains unclear how and to what extent the EVLP approach contributes to this metabolic decline. Although ascorbate has been used to mitigate the effects of ischemia-reperfusion injury, the nature of its effects during EVLP are also not clear. To address these uncertainties, this study monitored the energy status of lungs during EVLP and after the administration of ascorbate using (31)P and hyperpolarized (13)C NMR (nuclear magnetic resonance). Our experiments demonstrated that the oxidative phosphorylation capacity and pyruvate dehydrogenase flux of lungs decline during ex vivo perfusion. The addition of ascorbate to the perfusate prolonged lung viability by 80% and increased the hyperpolarized (13)C bicarbonate signal by a factor of 2.7. The effect of ascorbate is apparently due not to its antioxidant quality but rather to its ability to energize cellular respiration given that it increased the lung's energy charge significantly, whereas other antioxidants (glutathione and α-lipoic acid) did not alter energy metabolism. During ascorbate administration, inhibition of mitochondrial complex I with rotenone depressed energy charge and shifted the metabolic state of the lung toward glycolysis; reenergizing the electron transport chain with TMPD (N,N,N',N'-tetramethyl-p-phenylenediamine) recovered metabolic activity. This indicates that ascorbate slows the decline of the ex vivo perfused lung's mitochondrial activity through an independent interaction with the electron transport chain complexes. PMID:26165188

  11. In folio respiratory fluxomics revealed by 13C isotopic labeling and H/D isotope effects highlight the noncyclic nature of the tricarboxylic acid "cycle" in illuminated leaves.

    PubMed

    Tcherkez, Guillaume; Mahé, Aline; Gauthier, Paul; Mauve, Caroline; Gout, Elizabeth; Bligny, Richard; Cornic, Gabriel; Hodges, Michael

    2009-10-01

    While the possible importance of the tricarboxylic acid (TCA) cycle reactions for leaf photosynthesis operation has been recognized, many uncertainties remain on whether TCA cycle biochemistry is similar in the light compared with the dark. It is widely accepted that leaf day respiration and the metabolic commitment to TCA decarboxylation are down-regulated in illuminated leaves. However, the metabolic basis (i.e. the limiting steps involved in such a down-regulation) is not well known. Here, we investigated the in vivo metabolic fluxes of individual reactions of the TCA cycle by developing two isotopic methods, (13)C tracing and fluxomics and the use of H/D isotope effects, with Xanthium strumarium leaves. We provide evidence that the TCA "cycle" does not work in the forward direction like a proper cycle but, rather, operates in both the reverse and forward directions to produce fumarate and glutamate, respectively. Such a functional division of the cycle plausibly reflects the compromise between two contrasted forces: (1) the feedback inhibition by NADH and ATP on TCA enzymes in the light, and (2) the need to provide pH-buffering organic acids and carbon skeletons for nitrate absorption and assimilation. PMID:19675152

  12. An Oral Load of [13C3]Glycerol and Blood NMR Analysis Detect Fatty Acid Esterification, Pentose Phosphate Pathway, and Glycerol Metabolism through the Tricarboxylic Acid Cycle in Human Liver.

    PubMed

    Jin, Eunsook S; Sherry, A Dean; Malloy, Craig R

    2016-09-01

    Drugs and other interventions for high impact hepatic diseases often target biochemical pathways such as gluconeogenesis, lipogenesis, or the metabolic response to oxidative stress. However, traditional liver function tests do not provide quantitative data about these pathways. In this study, we developed a simple method to evaluate these processes by NMR analysis of plasma metabolites. Healthy subjects ingested [U-(13)C3]glycerol, and blood was drawn at multiple times. Each subject completed three visits under differing nutritional states. High resolution (13)C NMR spectra of plasma triacylglycerols and glucose provided new insights into a number of hepatic processes including fatty acid esterification, the pentose phosphate pathway, and gluconeogenesis through the tricarboxylic acid cycle. Fasting stimulated pentose phosphate pathway activity and metabolism of [U-(13)C3]glycerol in the tricarboxylic acid cycle prior to gluconeogenesis or glyceroneogenesis. Fatty acid esterification was transient in the fasted state but continuous under fed conditions. We conclude that a simple NMR analysis of blood metabolites provides an important biomarker of pentose phosphate pathway activity, triacylglycerol synthesis, and flux through anaplerotic pathways in mitochondria of human liver. PMID:27432878

  13. Effect of organic matter application on CP-MAS-13C-NMR spectra of humic acids from a brown soil

    NASA Astrophysics Data System (ADS)

    Dou, S.

    2009-04-01

    The humified SOM or humic substances (HS) composed of humic acid (HA), fulvic acid (FA) and humin (HM) represent the most microbially recalcitrant and stable reservoir of organic carbon in soil (Piccolo et al., 2004). OM applications can influence the amount and structural characteristics of HS(Dou et al., 2008). During the past few decades, there has been much research on HS, but their chemical structure is still not fully understood (Dong, 2006).CP-MAS-13C-NMR spectroscopy was considered as an effective method to study structures of HS without dissolving problem compared with liquid 13C-NMR (Conte et al., 1997; Dou et al., 2008). It can directly measure the carbon framework and reflect the nature of HS transformation after OM application (Spaccini et al., 2000). For that reason, this method was applied in this study. The objective of this paper was to clarify the effect of long term OM application on the changes of structural characteristics in HAs, which provided new information for improving soil fertility by OM application. The experiment was carried out on a brown soil (Paleudalf in USDA Soil Taxonomy) at Shenyang Agricultural University, Liaoning province, China (N41°48'-E123°25'). The experiment included 3 treatments: zero-treatment (CKbr), and two pig manure (PM) treatments (O1 and O2) at the rates of 0.9 t ha-1 and 1.8 t ha-1 of organic carbon, respectively. The samples of the HA fraction were extracted, separated and purified according to the method described by Dou et al. (1991). Elemental composition, Differential thermal analysis (DTA), -lgK value, FT-IR and CP-MAS- 13C-NMR of HAs were performed. Effects on the contents of orgaic carbon and its composition. The contents of TOC were from 8.77 g kg-1 to 12.25 g kg-1. The relative contents in TOC for WSS, HA, and FA were 6.87%, 14.2% and 19.8%. Comparing the CKbr, the contents of WSS, HA and FA for O1 and O2 increased, but relative contents of WSS and FA decreased. The content of the HA increased after

  14. A {sup 13}C NMR study of the condensation chemistry of acetone and acetaldehyde adsorbed at the Bronsted acid sites in H-ZSM-5

    SciTech Connect

    Biaglow, A.I.; Sepa, J.; Gorte, R.J.

    1995-02-01

    Several bimolecular, acid-catalyzed condensation reactions of acetone and acetaldehyde have been examined in H-ZSM-5, along with the adsorption complexes formed by the products, using {sup 13}C NMR. For acetone, the hydrogen-bonded adsorption complex is stable at room temperature and coverages below one molecule per Broensted acid site. Reaction to mesityl oxide occurs only at higher coverages or temperatures, which are necessary to induce site exchange. The adsorption complex exhibits reaction chemistry analogous to that observed in solution phase, forming adsorption complexes of chloroacetone upon exposure to Cl{sub 2} and of imines upon exposure to NH{sub 3} or dimethylamine. The reactions of acetaldehyde to crotonaldehyde and imines are similar, although they occur at a faster rate due to the higher mobility of this molecule. The adsorption complexes formed by acetone, acetaldehyde, and their condensation products can all be described as rigid, hydrogen-bonded complexes at low coverages. Complexes formed from imines and enamines exhibit isotropic chemical shifts nearly identical to those observed in magic acids, indicating that proton transfer is nearly complete for these molecules. The extent of proton transfer for the remaining molecules varies with the proton affinity of the molecule, ranging from close to complete proton transfer for mesityl oxide and crotonaldehyde to almost complete absence of proton transfer for the chloroacetones. The differences and similarities between these reactions in the zeolite and in solution phase are discussed, along with the implications for understanding the primary processes responsible for these reactions in zeolites. 34 refs., 16 figs., 1 tab.

  15. Effect of organic matter application on CP-MAS-13C-NMR spectra of humic acids from a brown soil

    NASA Astrophysics Data System (ADS)

    Dou, S.

    2009-04-01

    The humified SOM or humic substances (HS) composed of humic acid (HA), fulvic acid (FA) and humin (HM) represent the most microbially recalcitrant and stable reservoir of organic carbon in soil (Piccolo et al., 2004). OM applications can influence the amount and structural characteristics of HS(Dou et al., 2008). During the past few decades, there has been much research on HS, but their chemical structure is still not fully understood (Dong, 2006).CP-MAS-13C-NMR spectroscopy was considered as an effective method to study structures of HS without dissolving problem compared with liquid 13C-NMR (Conte et al., 1997; Dou et al., 2008). It can directly measure the carbon framework and reflect the nature of HS transformation after OM application (Spaccini et al., 2000). For that reason, this method was applied in this study. The objective of this paper was to clarify the effect of long term OM application on the changes of structural characteristics in HAs, which provided new information for improving soil fertility by OM application. The experiment was carried out on a brown soil (Paleudalf in USDA Soil Taxonomy) at Shenyang Agricultural University, Liaoning province, China (N41°48'-E123°25'). The experiment included 3 treatments: zero-treatment (CKbr), and two pig manure (PM) treatments (O1 and O2) at the rates of 0.9 t ha-1 and 1.8 t ha-1 of organic carbon, respectively. The samples of the HA fraction were extracted, separated and purified according to the method described by Dou et al. (1991). Elemental composition, Differential thermal analysis (DTA), -lgK value, FT-IR and CP-MAS- 13C-NMR of HAs were performed. Effects on the contents of orgaic carbon and its composition. The contents of TOC were from 8.77 g kg-1 to 12.25 g kg-1. The relative contents in TOC for WSS, HA, and FA were 6.87%, 14.2% and 19.8%. Comparing the CKbr, the contents of WSS, HA and FA for O1 and O2 increased, but relative contents of WSS and FA decreased. The content of the HA increased after

  16. GC-MS/MS survey of collision-induced dissociation of tert-butyldimethylsilyl-derivatized amino acids and its application to (13)C-metabolic flux analysis of Escherichia coli central metabolism.

    PubMed

    Okahashi, Nobuyuki; Kawana, Shuichi; Iida, Junko; Shimizu, Hiroshi; Matsuda, Fumio

    2016-09-01

    Stable isotope labeling experiments using mass spectrometry have been employed to investigate carbon flow levels (metabolic flux) in mammalian, plant, and microbial cells. To achieve a more precise (13)C-metabolic flux analysis ((13)C-MFA), novel fragmentations of tert-butyldimethylsilyl (TBDMS)-amino acids were investigated by gas chromatography-tandem mass spectrometry (GC-MS/MS). The product ion scan analyses of 15 TBDMS-amino acids revealed 24 novel fragment ions. The amino acid-derived carbons included in the five fragment ions were identified by the analyses of (13)C-labeled authentic standards. The identification of the fragment ion at m/z 170 indicated that the isotopic abundance of S-methyl carbon in methionine could be determined from the cleavage of C5 in the precursor of [M-159](+) (m/z 218). It was also confirmed that the precision of (13)C-MFA in Escherichia coli central carbon metabolism could be improved by introducing (13)C-labeling data derived from novel fragmentations. Graphical Abstract Novel collision-induced dissociation fragmentations of tert-butyldimethylsilyl amino acids were investigated and identified by GC-MS/MS. PMID:27342798

  17. FTIR spectra of the ν6 and ν8 bands of 13C formic acid molecule—Assignment of FIR-laser lines

    NASA Astrophysics Data System (ADS)

    Baskakov, O.; Horneman, V.-M.; Alanko, S.; Lohilahti, J.

    2008-05-01

    Two interacting vibrational modes ν6 and ν8 of 13C species of formic acid have been studied with high resolution FTIR spectroscopy in the range 900-1300 cm -1 with an instrumental resolution of 0.0018 cm -1. More than 10 000 lines have been assigned and fitted with a RMS deviation of 0.00024 cm -1. The band centers, as well as the rotational, quartic and sextic centrifugal distortion parameters and 6 interaction parameters have been determined. The obtained parameters have enabled the assignments of 24 FIR laser emissions of this molecule observed previously by Dangoisse and Glorieux [D. Dangoisse, P. Glorieux, J. Mol. Spectrosc. 92 (1982) 283-297], Luis et al. [G.M.R.S. Luis, E.M. Telles, A. Scalabrin, D. Pereira, IEEE J. Quantum. Electron. QE-34 (1998) 767-769], and Bertolini et al. [A. Bertolini, G. Carelli, C.A. Massa, A. Moretti, F. Strumia, Infrared Phys. Technol. 40 (1999) 33-36].

  18. Conformational analysis, spectroscopic study (FT-IR, FT-Raman, UV, 1H and 13C NMR), molecular orbital energy and NLO properties of 5-iodosalicylic acid

    NASA Astrophysics Data System (ADS)

    Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet

    2015-02-01

    In this study, 5-iodosalicylic acid (5-ISA, C7H5IO3) is structurally characterized by FT-IR, FT-Raman, NMR and UV spectroscopies. There are eight conformers, Cn, n = 1-8 for this molecule therefore the molecular geometry for these eight conformers in the ground state are calculated by using the ab-initio density functional theory (DFT) B3LYP method approach with the aug-cc-pVDZ-PP basis set for iodine and the aug-cc-pVDZ basis set for the other elements. The computational results identified that the most stable conformer of 5-ISA is the C1 form. The vibrational spectra are calculated DFT method invoking the same basis sets and fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method with PQS program. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis for C1 conformer were calculated using the same method. The energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT) results complement with the experimental findings. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) are calculated and presented. The NMR chemical shifts (1H and 13C) spectra are recorded and calculated using the gauge independent atomic orbital (GIAO) method. Mulliken atomic charges of the title molecule are also calculated, interpreted and compared with salicylic acid. The optimized bond lengths, bond angles and calculated NMR and UV, vibrational wavenumbers showed the best agreement with the experimental results.

  19. Preparation of 7-hydroxy-2-oxoindolin-3-ylacetic acid and its [13C2], [5-n-3H], and [5-n-3H]-7-O-glucosyl analogues for use in the study of indol-3-ylacetic acid catabolism

    NASA Technical Reports Server (NTRS)

    Lewer, P.; Bandurski, R. S. (Principal Investigator)

    1987-01-01

    An improved synthesis of 7-hydroxy-2-oxoindolin-3-ylacetic acid via the base-induced condensation reaction between oxalate esters and 7-benzyloxyindolin-2-one is described. 7-Benzyloxyindolin-2-one was prepared in four steps and 50% overall yield from 3-hydroxy-2-nitrotoluene. The yield of the title compound from 7-benzyloxyindolin-2-one was 56%. This route was used to prepare 7-hydroxy-2-oxoindolin-3-yl[13C2]acetic acid in 30% yield from [13C2]oxalic acid dihydrate. The method could not be extended to the preparation of the corresponding [14C2]-compound. However, an enzyme preparation from Zea mays roots catalysed the conversion of carrier-free [5-n-3H]indol-3-ylacetic acid with a specific activity of 16.7 Ci mmol-1 to a mixture of 7-hydroxy-2-oxo[5-n-3H]indolin-3-ylacetic acid and its [5-n-3H]-7-O-glucoside in ca. 3 and 40% radiochemical yield respectively. The glucoside was converted into the 7-hydroxy compound in 80% yield by means of beta-glucosidase.

  20. Seasonal variation of ecosystem respiration delta 13C in response to experimental permafrost thaw and vegetation removal in moist acidic tundra

    NASA Astrophysics Data System (ADS)

    Mauritz, M.; Pegoraro, E.; Salmon, V. G.; Natali, S.; Schuur, E.

    2015-12-01

    Permafrost soils store twice as much carbon (C) as is contained in the atmosphere and about one-third of global soil C. Under a warmer future climate, permafrost is expected to thaw and decompose, releasing C to the atmosphere, further amplifying global warming. However, studies show that warmer arctic temperatures promote plant growth, in addition to stimulating losses from the soil C pool. Using delta 13C of ecosystem respiration (Reco) during the seasonal cycle of active layer thaw, we seek to understand the effect of permafrost thaw on the relative contributions from microbial decomposition of soil C and more recently fixed, plant-dominated C. We measured weekly CO2 flux rates and delta 13C of Reco from experimentally warmed plots with rapid permafrost thaw and control thaw. Vegetation removal plots, in un-warmed tundra, were monitored to isolate the seasonal contributions from soil alone. We expected delta 13C to be dominated by plant activity in vegetated plots, particularly in areas with greater permafrost thaw because they have highest plant biomass. In vegetation removal plots we expected to see greater contribution from deep soil as seasonal thaw progressed. From May to July delta 13C was extremely variable early in the growing season, but became more uniform as vegetation greened and thaw deepened. In vegetated plots CO2 fluxes doubled, but remained constant in vegetation removal plots. This indicates that, with thaw, microbes had access to a more spatially uniform C substrate, but this had little effect on the magnitude of CO2 flux. Overall delta 13C in rapidly thawed plots was least enriched (-29.4 ‰), control plots intermediate (-28.9 ‰), and vegetation removal plots were most enriched (-28.5 ‰). This suggests that in vegetation removal plots microbes used more decomposed soil C as substrate, and much of the increase in CO2 flux in vegetated plots was the result of C recently fixed and contributed by plants.

  1. Effects of fish oil and starch added to a diet containing sunflower-seed oil on dairy goat performance, milk fatty acid composition and in vivo delta9-desaturation of [13C]vaccenic acid.

    PubMed

    Bernard, Laurence; Mouriot, Julien; Rouel, Jacques; Glasser, Frédéric; Capitan, Pierre; Pujos-Guillot, Estelle; Chardigny, Jean-Michel; Chilliard, Yves

    2010-08-01

    The potential benefits on human health have prompted an interest in developing nutritional strategies for specifically increasing rumenic acid (RA) in ruminant milk. The aims of the present study were to (i) compare two dietary treatments with lipid supplements on milk yield and composition, (ii) measure the in vivo delta9-desaturation of vaccenic acid (VA) to RA using 13C-labelled VA and (iii) determine the effect of the dietary treatments on this variable. Treatments were 90 g sunflower-seed oil (SO) per d or 60 g sunflower-seed oil and 30 g fish oil per d plus additional starch (SFO), in a grassland hay-based diet given to eight Alpine goats in a 2 x 2 cross-over design with 21 d experimental periods. Milk yield and composition were similar between treatments. Goats fed SFO had higher milk 6 : 0-16 : 0 concentration, lower milk sigmaC18 concentrations and showed no effect on milk VA and RA, compared with SO. At the end of the experiment, intravenous injection of 1.5 g [13C]VA followed by measurements of milk lipid 13C enrichment showed that in vivo 31.7 and 31.6 % of VA was delta9-desaturated into milk RA in the caprine with the SO and SFO treatments, respectively. The expression of genes encoding for delta9-desaturase (or stearoyl-CoA desaturase; SCD1, SCD5) in mammary tissues and four milk delta9-desaturation ratios were similar between treatments. In conclusion, the present study provides the first estimates of in vivo endogenous synthesis of RA (63-73 % of milk RA) from VA in goats, and shows no difference between the two lipid supplements compared. PMID:20307350

  2. Uptake of algal carbon and the synthesis of an "essential" fatty acid by Uvigerina ex. gr. semiornata (Foraminifera) within the Pakistan margin oxygen minimum zone: evidence from fatty acid biomarker and 13C tracer experiments

    NASA Astrophysics Data System (ADS)

    Larkin, K. E.; Gooday, A. J.; Woulds, C.; Jeffreys, R.; Schwartz, M.; Cowie, G.; Whitcraft, C.; Levin, L.; Dick, J. R.; Pond, D. W.

    2014-01-01

    Foraminifera are an important component of benthic communities in oxygen depleted settings, where they potentially play a~significant role in the processing of organic matter. We tracked the uptake of a 13C-labeled algal food source into individual fatty acids in the benthic foraminiferal species, Uvigerina ex. gr. semiornata, from the Arabian Sea oxygen minimum zone (OMZ). The tracer experiments were conducted on the Pakistan Margin during the late/post monsoon period (August-October 2003). A monoculture of the diatom Thalassiosira weisflogii was 13C-labeled and used to simulate a pulse of phytoplankton in two complementary experiments. A lander system was used for in situ incubations at 140 m and for 2.5 days duration, whilst a laboratory incubation used an oxystat system to maintain ambient dissolved oxygen concentrations. These shipboard experiments were terminated after 5 days. Uptake of diatoms was rapid, with high incorporation of diatom fatty acids into foraminifera after ~2 days in both experiments. Ingestion of the diatom food source was indicated by the increase over time in the quantity of diatom biomarker fatty acids in the foraminifera and by the high percentage of 13C in many of the fatty acids present at the endpoint of both in~situ and laboratory-based experiments. These results indicate that U. ex. gr. semiornata rapidly ingested the diatom food source and that this foraminifera will play an important role in the short-term cycling of organic matter within this OMZ environment. The experiments also suggested that U. ex. gr. semiornata consumed non-labeled bacterial food items, particularly bacteria, and synthesised the polyunsaturated fatty acid 20:4(n-6) de novo. 20:4(n-6) is often abundant in benthic fauna yet its origins and function have remained unclear. This study demonstrates that U. ex. gr. semiornata is capable of de novo synthesis of this "essential fatty acid" and is potentially a major source of this dietary nutrient in benthic food

  3. Determination of 13C isotopic enrichment of valine and threonine by GC-C-IRMS after formation of the N(O,S)-ethoxycarbonyl ethyl ester derivatives of the amino acids.

    PubMed

    Godin, Jean-Philippe; Faure, Magali; Breuille, Denis; Hopfgartner, Gérard; Fay, Laurent-Bernard

    2007-06-01

    We describe a new method of assessing, in a single run, (13)C isotopic enrichment of both Val and Thr by gas chromatography-combustion-isotope-ratio mass spectrometry (GC-C-IRMS). This method characterised by a rapid one-step derivatisation procedure performed at room temperature to form the N(O,S)-ethoxycarbonyl ethyl ester derivatives, and a polar column for GC. The suitability of this method for Val and Thr in in-vivo samples (mucosal hydrolysate) was demonstrated by studying protein metabolism with two tracers ((13)C-valine or (13)C-threonine). The intra-day and inter-day repeatability were both assessed either with standards or with in-vivo samples at natural abundance and at low (13)C isotopic enrichment. For inter-day repeatability CVs were between 0.8 and 1.5% at natural abundance and lower than 5.5% at 0.112 and 0.190 atom% enrichment for Val and Thr, respectively. Overall isotopic precision was studied for eleven standard amino acid derivatives (those of Val, Ala, Leu, Iso, Gly, Pro, Asp, Thr, Ser, Met, and Phe) and was assessed at 0.32 per thousand. The (13)C isotopic measurement was then extended to the other amino acids (Ala, Val, Leu, Iso, Gly, Pro, Thr, and Phe) at natural abundance for in-vivo samples. The isotopic precision was better than 0.002 atom% per amino acid (for n = 4 rats). This analytical method was finally applied to an animal study to measure Thr utilization in protein synthesis. PMID:17468859

  4. Uptake of algal carbon and the likely synthesis of an "essential" fatty acid by Uvigerina ex. gr. semiornata (Foraminifera) within the Pakistan margin oxygen minimum zone: evidence from fatty acid biomarker and 13C tracer experiments

    NASA Astrophysics Data System (ADS)

    Larkin, K. E.; Gooday, A. J.; Woulds, C.; Jeffreys, R. M.; Schwartz, M.; Cowie, G.; Whitcraft, C.; Levin, L.; Dick, J. R.; Pond, D. W.

    2014-07-01

    Foraminifera are an important component of benthic communities in oxygen-depleted settings, where they potentially play a significant role in the processing of organic matter. We tracked the uptake of a 13C-labelled algal food source into individual fatty acids in the benthic foraminiferal species Uvigerina ex. gr. semiornata from the Arabian Sea oxygen minimum zone (OMZ). The tracer experiments were conducted on the Pakistan margin during the late/post monsoon period (August-October 2003). A monoculture of the diatom Thalassiosira weisflogii was 13C-labelled and used to simulate a pulse of phytoplankton in two complementary experiments. A lander system was used for in situ incubations at 140 m water depth and for 2.5 days in duration. Shipboard laboratory incubations of cores collected at 140 m incorporated an oxystat system to maintain ambient dissolved oxygen concentrations and were terminated after 5 days. Uptake of diatoms was rapid, with a high incorporation of diatom fatty acids into foraminifera after ~ 2 days in both experiments. Ingestion of the diatom food source was indicated by the increase over time in the quantity of diatom biomarker fatty acids in the foraminifera and by the high percentage of 13C in many of the fatty acids present at the endpoint of both in situ and laboratory-based experiments. These results indicate that acid" is often abundant in benthic fauna, yet

  5. A medium-chain fatty acid as an alternative energy source in mouse preimplantation development

    PubMed Central

    Yamada, Mitsutoshi; Takanashi, Kazumi; Hamatani, Toshio; Hirayama, Akiyoshi; Akutsu, Hidenori; Fukunaga, Tomoko; Ogawa, Seiji; Sugawara, Kana; Shinoda, Kosaku; Soga, Tomoyoshi; Umezawa, Akihiro; Kuji, Naoaki; Yoshimura, Yasunori; Tomita, Masaru

    2012-01-01

    To further optimize the culturing of preimplantation embryos, we undertook metabolomic analysis of relevant culture media using capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS). We detected 28 metabolites: 23 embryo-excreted metabolites including 16 amino acids and 5 media-derived metabolites (e.g., octanoate, a medium-chain fatty acid (MCFA)). Due to the lack of information on MCFAs in mammalian preimplantation development, this study examined octanoate as a potential alternative energy source for preimplantation embryo cultures. No embryos survived in culture media lacking FAs, pyruvate, and glucose, but supplementation of octanoate rescued the embryonic development. Immunoblotting showed significant expression of acyl-CoA dehydrogenase and hydroxyacyl-CoA dehydrogenase, important enzymes for ß-oxidation of MCFAs, in preimplantation embryo. Furthermore, CE-TOFMS traced [1-13C8] octanoate added to the culture media into intermediate metabolites of the TCA cycle via ß-oxidation in mitochondria. These results are the first demonstration that octanoate could provide an efficient alternative energy source throughout preimplantation development. PMID:23226596

  6. Application of ChemDraw NMR Tool: Correlation of Program-Generated (Super 13)C Chemical Shifts and pK[subscript a] Values of Para-Substituted Benzoic Acids

    ERIC Educational Resources Information Center

    Hongyi Wang

    2005-01-01

    A study uses the ChemDraw nuclear magnetic resonance spectroscopy (NMR) tool to process 15 para-substituted benzoic acids and generate (super 13)C NMR chemical shifts of C1 through C5. The data were plotted against their pK[subscript a] value and a fairly good linear fit was found for pK[subscript a] versus delta[subscript c1].

  7. Short communication: Using diurnal patterns of (13)C enrichment of CO2 to evaluate the effects of nitrate and docosahexaenoic acid on fiber degradation in the rumen of lactating dairy cows.

    PubMed

    Klop, G; Bannink, A; Dieho, K; Gerrits, W J J; Dijkstra, J

    2016-09-01

    Nitrate decreases enteric CH4 production in ruminants, but may also negatively affect fiber degradation. In this experiment, 28 lactating Holstein dairy cows were grouped into 7 blocks. Within blocks, cows were randomly assigned to 1 of 4 isonitrogenous treatments in a 2×2 factorial arrangement: control (CON); NO3 [21g of nitrate/kg of dry matter (DM)]; DHA [3g of docosahexaenoic acid (DHA)/kg of DM]; or NO3+DHA (21g of nitrate/kg of DM and 3g of DHA/kg of DM). Cows were fed a total mixed ration consisting of 21% grass silage, 49% corn silage, and 30% concentrates on a DM basis. Based on the difference in natural (13)C enrichment and neutral detergent fiber and starch content between grass silage and corn silage, we investigated whether a negative effect on rumen fiber degradation could be detected by evaluating diurnal patterns of (13)C enrichment of exhaled carbon dioxide. A significant nitrate × DHA interaction was found for neutral detergent fiber digestibility, which was reduced on the NO3 treatment to an average of 55%, as compared with 61, 64, and 65% on treatments CON, DHA, and NO3+DHA, respectively. Feeding nitrate, but not DHA, resulted in a pronounced increase in (13)C enrichment of CO2 in the first 3 to 4 h after feeding only. Results support the hypothesis that effects of a feed additive on the rate of fiber degradation in the rumen can be detected by evaluating diurnal patterns of (13)C enrichment of CO2. To be able to detect this, the main ration components have to differ considerably in fiber and nonfiber carbohydrate content as well as in natural (13)C enrichment. PMID:27344384

  8. Large-scale synthesis of isotopically labeled 13C2-tenuazonic acid and development of a rapid HPLC-MS/MS method for the analysis of tenuazonic acid in tomato and pepper products.

    PubMed

    Lohrey, Lilia; Marschik, Stefanie; Cramer, Benedikt; Humpf, Hans-Ulrich

    2013-01-01

    Tenuazonic acid is a fungal secondary metabolite that is produced by a number of Alternaria species and is therefore a natural contaminant of food and feed samples. This paper describes a new strategy for the efficient and economical large-scale synthesis of the isotopically labeled internal standard (13)C(2)-tenuazonic acid via a three-step procedure. Furthermore, a new reliable and quick method based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) cleanup is presented for the determination of tenuazonic acid in food and feed samples utilizing high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) by application of the stable isotope dilution analysis. This new method has a limit of detection (LOD) of 0.86 μg/kg and a limit of quantitation (LOQ) of 2.89 μg/kg. In total 26 tomato samples and 4 bell pepper samples from the German market were analyzed. Tenuazonic acid was found in each sample with levels from 3 to 2330 μg/kg. PMID:23230907

  9. Cholesteryl octanoate breath test. Preliminary studies on a new noninvasive test of human pancreatic exocrine function.

    PubMed

    Cole, S G; Rossi, S; Stern, A; Hofmann, A F

    1987-12-01

    A new breath test for noninvasive assessment of pancreatic exocrine function in humans was developed. The test is based on the hydrolysis of cholesteryl-[1-14C]octanoate by pancreatic carboxyl ester lipase (cholesterol esterase) with subsequent absorption and hepatic metabolism of the liberated octanoate to 14CO2. The rate at which 14CO2 appears in breath appeared to be proportional to the rate of hydrolysis. The substrate is administered as a gum acacia stabilized emulsion of vegetable oil (18 g) containing cholesteryl octanoate (2 g; 4.4 microCi) dispersed in a 500-ml isotonic meal. Tests were performed in 6 healthy volunteers and 11 patients with pancreatic disease with varying degrees of steatorrhea. In healthy subjects, 14CO2 output was rapid with peak output occurring at 60-90 min in all subjects; cumulative output in 4 h averaged 30%. Duplicate studies indicated that the time-course of 14CO2 recovery was reproducible. The pattern of 14CO2 output in patients with pancreatic disease varied widely. Patients without steatorrhea (fecal fat less than or equal to 7 g/day) or with mild steatorrhea (fecal fat 7-11 g/day) had normal or near normal patterns of 14CO2 output, whereas patients with moderate or severe steatorrhea (fecal fat greater than 11 g/day) expired 14CO2 at a rate one-third to one-tenth that of the healthy volunteers. Addition of pancreatic enzyme supplementation to the test meal increased 14CO2 output in 6 of 6 patients with moderate or severe steatorrhea, suggesting that the activity of pancreatic carboxyl ester lipase was rate limiting in these patients. In an additional study in a healthy volunteer, 14CO2 and 13CO2 were measured simultaneously in breath after ingestion of a test meal containing cholesteryl-[1-13C]octanoate and 14C-octanoate. 14CO2 was expired more rapidly than 13CO2, suggesting that hydrolysis of the substrate may also be rate limiting in healthy volunteers. These studies indicate that severe pancreatic exocrine dysfunction can

  10. Transformation of 17β-estradiol in humic acid solution by ε-MnO2 nanorods as probed by high-resolution mass spectrometry combined with (13)C labeling.

    PubMed

    Sun, Kai; Liang, Shangtao; Kang, Fuxing; Gao, Yanzheng; Huang, Qingguo

    2016-07-01

    Steroidal estrogens (SEs), widespread in aquatic systems, have a potential to disrupt the endocrine system of wildlife species and humans. In our experiments, the performance of ε-MnO2 nanorods in transforming 17β-estradiol (E2) was investigated, and the effect of humic acid (HA) on the reaction behaviors was systematically characterized. Reconfiguration of humic molecules was also investigated by high-performance size exclusion chromatography (HPSEC). Results indicated that ε-MnO2 nanomaterials ensured efficient removal of E2 from the aqueous solution. The presence of HA hindered the transformation of E2, while enhanced the cross-coupling between E2 and humic molecules. In particular, we used a mixture of un-labeled E2 and (13)C3-labeled E2 at a 1: 1 set ratio (w/w) to probe the reaction products via high-resolution mass spectrometry (HRMS). The combination of HRMS and (13)C3-labeling revealed the intermediate products including estrone (E1), and hydroxylated, quinone-like, and ring-opened species, as well as E2 dimer and trimer. More importantly, possible cross-coupling products between E2 and HA were also identified. A reaction mechanism including two-electron oxidation and single-electron oxidation was proposed. The applied analytical approach using HRMS along with (13)C3-labeling for reaction-product identification is crucial to understanding the role of HA in the transformation of SEs. PMID:27086077

  11. Polyamine flux analysis by determination of heavy isotope incorporation from 13C, 15N-enriched amino acids into polyamines by LC-MS/MS.

    PubMed

    Cerrada-Gimenez, Marc; Häkkinen, Merja R; Vepsäläinen, Jouko; Auriola, Seppo; Alhonen, Leena; Keinänen, Tuomo A

    2012-02-01

    The study of polyamine flux, i.e. the circulating flow of polyamines through the interconnected biosynthetic and catabolic pathways, is of considerable interest because of the established links between the polyamine metabolism and many diseases, such as cancer and diabetes. To study polyamine flux in detail, a novel method based on following the label incorporation from the (13)C, (15)N-labeled polyamine precursors, arginine, methionine and ornithine, into polyamines by LC-MS/MS was implemented. This methodology was tested on three distinct cell lines with different spermidine/spermine-N (1)-acetyltransferase (SSAT) expression levels, i.e. non-transgenic, transgenic and knockout. These trials allowed the identification of the critical conditions for the successful polyamine flux measurement, such as the functional time frame of label incorporation, until plateau phase with the selected precursor is reached. The novel LC-MS/MS-based method for polyamine flux overcame the limitations of previous existing methodologies, with baseline separation of the different polyamine species and the exact quantification of the incorporated label. Moreover, the obtained results clearly show that the increased SSAT expression is associated with accelerated polyamine flux. PMID:21818565

  12. Optimization of amino acid type-specific 13C and 15N labeling for the backbone assignment of membrane proteins by solution- and solid-state NMR with the UPLABEL algorithm.

    PubMed

    Hefke, Frederik; Bagaria, Anurag; Reckel, Sina; Ullrich, Sandra Johanna; Dötsch, Volker; Glaubitz, Clemens; Güntert, Peter

    2011-02-01

    We present a computational method for finding optimal labeling patterns for the backbone assignment of membrane proteins and other large proteins that cannot be assigned by conventional strategies. Following the approach of Kainosho and Tsuji (Biochemistry 21:6273-6279 (1982)), types of amino acids are labeled with (13)C or/and (15)N such that cross peaks between (13)CO(i - 1) and (15)NH(i) result only for pairs of sequentially adjacent amino acids of which the first is labeled with (13)C and the second with (15)N. In this way, unambiguous sequence-specific assignments can be obtained for unique pairs of amino acids that occur exactly once in the sequence of the protein. To be practical, it is crucial to limit the number of differently labeled protein samples that have to be prepared while obtaining an optimal extent of labeled unique amino acid pairs. Our computer algorithm UPLABEL for optimal unique pair labeling, implemented in the program CYANA and in a standalone program, and also available through a web portal, uses combinatorial optimization to find for a given amino acid sequence labeling patterns that maximize the number of unique pair assignments with a minimal number of differently labeled protein samples. Various auxiliary conditions, including labeled amino acid availability and price, previously known partial assignments, and sequence regions of particular interest can be taken into account when determining optimal amino acid type-specific labeling patterns. The method is illustrated for the assignment of the human G-protein coupled receptor bradykinin B2 (B(2)R) and applied as a starting point for the backbone assignment of the membrane protein proteorhodopsin. PMID:21170670

  13. S100A13-C2A binary complex structure-a key component in the acidic fibroblast growth factor for the non-classical pathway

    SciTech Connect

    Mohan, Sepuru K.; Rani, Sandhya G.; Kumar, Sriramoju M.; Yu Chin

    2009-03-13

    pathway, we have studied the interactions of S100A13 with C2A by {sup 1}H-{sup 15}N HSQC titration and 3D-filtered NOESY experiments. We characterized the binary complex structure of S100A13-C2A by using a variety of multi-dimensional NMR experiments. This complex acts as a template for FGF-1 dimerization and multiprotein complex formation.

  14. /sup 13/C nuclear magnetic resonance studies of cardiac metabolism

    SciTech Connect

    Seeholzer, S.H.

    1985-01-01

    The last decade has witnessed the increasing use of Nuclear Magnetic Resonance (NMR) techniques for following the metabolic fate of compounds specifically labeled with /sup 13/C. The goals of the present study are: (1) to develop reliable quantitative procedures for measuring the /sup 13/C enrichment of specific carbon sites in compounds enriched by the metabolism of /sup 13/C-labeled substrates in rat heart, and (2) to use these quantitative measurements of fractional /sup 13/C enrichment within the context of a mathematical flux model describing the carbon flow through the TCA cycle and ancillary pathways, as a means for obtaining unknown flux parameters. Rat hearts have been perfused in vitro with various combinations of glucose, acetate, pyruvate, and propionate to achieve steady state flux conditions, followed by perfusion with the same substrates labeled with /sup 13/C in specific carbon sites. The hearts were frozen at different times after addition of /sup 13/C-labeled substrates and neutralized perchloric acid extracts were used to obtain high resolution proton-decoupled /sup 13/C NMR spectra at 90.55 MHz. The fractional /sup 13/C enrichment (F.E.) of individual carbon sites in different metabolites was calculated from the area of the resolved resonances after correction for saturation and nuclear Overhauser effects. These F.E. measurements by /sup 13/C NMR were validated by the analysis of /sup 13/C-/sup 1/H scalar coupling patterns observed in /sup 1/H NMR spectra of the extracted metabolites. The results obtained from perfusion of hearts glucose plus either (2-/sup 13/C) acetate or (3-/sup 13/C) pyruvate are similar to those obtained by previous investigators using /sup 14/C-labeled substrates.

  15. Assessing the potential of amino acid 13C patterns as a carbon source tracer in marine sediments: effects of algal growth conditions and sedimentary diagenesis

    NASA Astrophysics Data System (ADS)

    Larsen, T.; Bach, L. T.; Salvatteci, R.; Wang, Y. V.; Andersen, N.; Ventura, M.; McCarthy, M. D.

    2015-08-01

    Burial of organic carbon in marine sediments has a profound influence in marine biogeochemical cycles and provides a sink for greenhouse gases such as CO2 and CH4. However, tracing organic carbon from primary production sources as well as its transformations in the sediment record remains challenging. Here we examine a novel but growing tool for tracing the biosynthetic origin of amino acid carbon skeletons, based on naturally occurring stable carbon isotope patterns in individual amino acids (δ13CAA). We focus on two important aspects for δ13CAA utility in sedimentary paleoarchives: first, the fidelity of source diagnostic of algal δ13CAA patterns across different oceanographic growth conditions, and second, the ability of δ13CAA patterns to record the degree of subsequent microbial amino acid synthesis after sedimentary burial. Using the marine diatom Thalassiosira weissflogii, we tested under controlled conditions how δ13CAA patterns respond to changing environmental conditions, including light, salinity, temperature, and pH. Our findings show that while differing oceanic growth conditions can change macromolecular cellular composition, δ13CAA isotopic patterns remain largely invariant. These results emphasize that δ13CAA patterns should accurately record biosynthetic sources across widely disparate oceanographic conditions. We also explored how δ13CAA patterns change as a function of age, total nitrogen and organic carbon content after burial, in a marine sediment core from a coastal upwelling area off Peru. Based on the four most informative amino acids for distinguishing between diatom and bacterial sources (i.e., isoleucine, lysine, leucine and tyrosine), bacterially derived amino acids ranged from 10 to 15 % in the sediment layers from the last 5000 years, and up to 35 % during the last glacial period. The greater bacterial contributions in older sediments indicate that bacterial activity and amino acid resynthesis progressed, approximately as a

  16. Assessing the potential of amino acid δ13C patterns as a carbon source tracer in marine sediments: effects of algal growth conditions and sedimentary diagenesis

    NASA Astrophysics Data System (ADS)

    Larsen, T.; Bach, L. T.; Salvatteci, R.; Wang, Y. V.; Andersen, N.; Ventura, M.; McCarthy, M. D.

    2015-01-01

    Burial of organic carbon in marine sediments has a profound influence in marine biogeochemical cycles, and provides a sink for greenhouse gases such as CO2 and CH4. However, tracing organic carbon from primary production sources as well as its transformations in the sediment record remains challenging. Here we examine a novel but growing tool for tracing biosynthetic origin of amino acid carbon skeletons, based on natural occurring stable carbon isotope patterns in individual amino acids (δ13CAA). We focus on two important aspects for δ13CAA utility in sedimentary paleoarchives: first, the fidelity of source diagnostic of algal δ13CAA patterns across different oceanographic growth conditions; and second, the ability of δ13CAA patterns to record the degree of subsequent microbial amino acid synthesis after sedimentary burial. Using the marine diatom Thalassiosira weissflogii, we tested under controlled conditions how δ13CAA patterns respond to changing environmental conditions, including light, salinity, temperature, and pH. Our findings show that while differing oceanic growth conditions can change macromolecular cellular composition, δ13CAA isotopic patterns remain largely invariant. These results underscore that δ13CAA patterns should accurately record biosynthetic sources across widely disparate oceanographic conditions. We also explored how δ13CAA patterns change as a function of age, total nitrogen and organic carbon content after burial, in a marine sediment core from a coastal upwelling area off Peru. Based on the four most informative amino acids for distinguishing between diatom and bacterial sources (i.e. isoleucine, lysine, leucine and tyrosine), bacterial derived amino acids ranged from 10-15% in the sediment layers from the last 5000 years to 35% during the last glacial period. The larger bacterial fractions in older sediments indicate that bacterial activity and amino acid resynthesis progressed, approximately as a function of sediment age, to

  17. Spectroscopic (FT-IR, FT-Raman, 1H, 13C NMR, UV/VIS), thermogravimetric and antimicrobial studies of Ca(II), Mn(II), Cu(II), Zn(II) and Cd(II) complexes of ferulic acid

    NASA Astrophysics Data System (ADS)

    Kalinowska, M.; Piekut, J.; Bruss, A.; Follet, C.; Sienkiewicz-Gromiuk, J.; Świsłocka, R.; Rzączyńska, Z.; Lewandowski, W.

    2014-03-01

    The molecular structure of Mn(II), Cu(II), Zn(II), Cd(II) and Ca(II) ferulates (4-hydroxy-3-methoxycinnamates) was studied. The selected metal ferulates were synthesized. Their composition was established by means of elementary and thermogravimetric analysis. The following spectroscopic methods were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance (13C, 1H NMR) and ultraviolet-visible (UV/VIS). On the basis of obtained results the electronic charge distribution in studied metal complexes in comparison with ferulic acid molecule was discussed. The microbiological study of ferulic acid and ferulates toward Escherichia coli, Bacillus subtilis, Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris was done.

  18. Sequence-specific {sup 1}H, {sup 13}C, and {sup 15}N resonance assignments for intestinal fatty-acid-binding protein complexed with palmitate (15.4 kDA)

    SciTech Connect

    Hodsdon, M.E.; Toner, J.J.; Cistola, D.P.

    1994-12-01

    Intestinal fatty-acid-binding protein (I-FABP) belongs to a family of soluble, cytoplasmic proteins that are thought to function in the intracellular transport and trafficking of polar lipids. Individual members of this protein family have distinct specificities and affinities for fatty acids, cholesterol, bile salts, and retinoids. We are comparing several retinol- and fatty-acid-binding proteins from intestine in order to define the factors that control molecular recognition in this family of proteins. We have established sequential resonance assignments for uniformly {sup 13}C/{sup 15}N-enriched I-FABP complexed with perdeuterated palmitate at pH7.2 and 37{degrees}C. The assignment strategy was similar to that introduced for calmodulin. We employed seven three-dimensional NMR experiments to establish scalar couplings between backbone and sidechain atoms. Backbone atoms were correlated using triple-resonance HNCO, HNCA, TOCSY-HMQC, HCACO, and HCA(CO)N experiments. Sidechain atoms were correlated using CC-TOCSY, HCCH-TOCSY, and TOCSY-HMQC. The correlations of peaks between three-dimensional spectra were established in a computer-assisted manner using NMR COMPASS (Molecular Simulations, Inc.) Using this approach, {sup 1}H, {sup 13}C, and {sup 15}N resonance assignments have been established for 120 of the 131 residues of I-FABP. For 18 residues, amide {sup 1}H and {sup 15}N resonances were unobservable, apparently because of the rapid exchange of amide protons with bulk water at pH 7.2. The missing amide protons correspond to distinct amino acid patterns in the protein sequence, which will be discussed. During the assignment process, several sources of ambiguity in spin correlations were observed. To overcome this ambiguity, the additional inter-residue correlations often observed in the HNCA experiment were used as cross-checks for the sequential backbone assignments.

  19. Metabolic flux analysis of recombinant Pichia pastoris growing on different glycerol/methanol mixtures by iterative fitting of NMR-derived (13)C-labelling data from proteinogenic amino acids.

    PubMed

    Jordà, Joel; de Jesus, Sérgio S; Peltier, Solenne; Ferrer, Pau; Albiol, Joan

    2014-01-25

    The yeast Pichia pastoris has emerged as one of the most promising yeast cell factories for the production of heterologous proteins. The readily available genetic tools and the ease of high-cell density cultivations using methanol or glycerol/methanol mixtures are among the key factors for this development. Previous studies have shown that the use of mixed feeds of glycerol and methanol seem to alleviate the metabolic burden derived from protein production, allowing for higher specific and volumetric process productivities. However, initial studies of glycerol/methanol co-metabolism in P. pastoris by classical metabolic flux analyses using (13)C-derived Metabolic Flux Ratio (METAFoR) constraints were hampered by the reduced labelling information obtained when using C3:C1 substrate mixtures in relation to the conventional C6 substrate, that is, glucose. In this study, carbon flux distributions through the central metabolic pathways in glycerol/methanol co-assimilation conditions have been further characterised using biosynthetically directed fractional (13)C labelling. In particular, metabolic flux distributions were obtained under 3 different glycerol/methanol ratios and growth rates by iterative fitting of NMR-derived (13)C-labelling data from proteinogenic amino acids using the software tool (13)CFlux2. Specifically, cells were grown aerobically in chemostat cultures fed with 80:20, 60:40 and 40:60 (w:w) glycerol/methanol mixtures at two dilutions rates (0.05 hour(-1) and 0.16 hour(-1)), allowing to obtain additional data (biomass composition and extracellular fluxes) to complement pre-existing datasets. The performed (13)C-MFA reveals a significant redistribution of carbon fluxes in the central carbon metabolism as a result of the shift in the dilution rate, while the ratio of carbon sources has a lower impact on carbon flux distribution in cells growing at the same dilution rate. At low growth rate, the percentage of methanol directly dissimilated to CO2 ranges

  20. Late Holocene Plankton Domain Shifts in the North Pacific Subtropical Gyre Revealed by Amino Acid Specific δ13C and δ15N Records from Proteinaceous Deep-Sea Corals

    NASA Astrophysics Data System (ADS)

    Sherwood, O.; McMahon, K.; Guilderson, T. P.; Mccarthy, M. D.

    2014-12-01

    Recent observations from station ALOHA have framed a new paradigm about the dynamic nature of subtropical ocean gyres. These vast regions are now known to vary physically and biologically, over a range of timescales, with important implications for the export of carbon to the deep ocean. In the largest of these gyres, the North Pacific subtropical gyre (NPSG), primary production has increased in recent decades despite a reduction in nutrient supply to surface waters. This is thought to be the result of a shift in plankton community structure from mostly eukaryotes to mostly dinitrogen-fixing prokaryotes. It remains uncertain, however, whether the recent plankton community domain shift can be linked to cyclical climate variability or a long-term global warming trend. To establish historical trends, we analyzed nitrogen (δ15N) and carbon (δ13C) isotopic records preserved in the skeletons of extraordinarily long-lived, proteinaceous deep-sea corals, which feed on, and therefore serve as a proxy for, exported productivity. Specimens of Hawaiian gold coral (Kulamanamana haumeaae) were collected from the Hawaiian archipelago and sampled across the skeletal growth rings to generate high-resolution (5 yr), millennial-length records of "bulk" δ15N and δ13C. After a millennium of relatively minor fluctuation, δ15N decreased by up to 2 per mil between 1850 and the present. Analysis of amino-acid-specific δ15N on a subset of the samples, combined with isotopic mass balance between nitrate and nitrogen fixation, implied a 17 to 27 % increase in nitrogen fixation as the underlying cause for the observed trends. This interpretation is supported by analysis of the δ13C of essential amino acids, which serve as isotopic fingerprints of primary producer origin. Together, these independent lines of evidence describe a domain shift from a dominantly eukaryotic to dinitrogen-fixing prokaryotic plankton community. This shift has been ongoing since the end of the Little Ice Age

  1. Spectroscopic (FT-IR, FT-Raman, UV absorption, 1H and 13C NMR) and theoretical (in B3LYP/6-311++G** level) studies on alkali metal salts of caffeic acid

    NASA Astrophysics Data System (ADS)

    Świsłocka, Renata

    The effect of some metals on the electronic system of benzoic and nicotinic acids has recently been investigated by IR, Raman and UV spectroscopy [1-3]. Benzoic and nicotinic acids are regarded model systems representing a wide group of aromatic ligands which are incorporated into enzymes. In this work the FT-IR (in solid state and in solution), FT-Raman, UV absorption and 1H and 13C NMR spectra of caffeic acid (3,4-dihydroxycinnamic acid) and its salts with lithium, sodium, potassium, rubidium and caesium were registered, assigned and analyzed. The effect of alkali metals on the electronic system of ligands was discussed. Studies of differences in the number and position of bands from the IR, Raman, UV absorption spectra and chemical shifts from NMR spectra allowed to conclude on the distribution of electronic charge in the molecules, the delocalization energy of π electrons and the reactivity of ligands in metal complexes. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G** basis set. Bond lengths, angles and dipole moments for the optimized structures of caffeic acid and lithium, sodium, potassium caffeinates were also calculated. The theoretical wavenumbers and intensities of IR spectra were obtained. The calculated parameters were compared to the experimental characteristics of investigated compounds. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris.

  2. Spectroscopic (FT-IR, FT-Raman, UV absorption, 1H and 13C NMR) and theoretical (in B3LYP/6-311++G** level) studies on alkali metal salts of caffeic acid.

    PubMed

    Świsłocka, Renata

    2013-01-01

    The effect of some metals on the electronic system of benzoic and nicotinic acids has recently been investigated by IR, Raman and UV spectroscopy [1-3]. Benzoic and nicotinic acids are regarded model systems representing a wide group of aromatic ligands which are incorporated into enzymes. In this work the FT-IR (in solid state and in solution), FT-Raman, UV absorption and (1)H and (13)C NMR spectra of caffeic acid (3,4-dihydroxycinnamic acid) and its salts with lithium, sodium, potassium, rubidium and caesium were registered, assigned and analyzed. The effect of alkali metals on the electronic system of ligands was discussed. Studies of differences in the number and position of bands from the IR, Raman, UV absorption spectra and chemical shifts from NMR spectra allowed to conclude on the distribution of electronic charge in the molecules, the delocalization energy of π electrons and the reactivity of ligands in metal complexes. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G** basis set. Bond lengths, angles and dipole moments for the optimized structures of caffeic acid and lithium, sodium, potassium caffeinates were also calculated. The theoretical wavenumbers and intensities of IR spectra were obtained. The calculated parameters were compared to the experimental characteristics of investigated compounds. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris. PMID:22369898

  3. A Column Experiment To Determine Black Shale Degradation And Colonization By Means of δ13C and 14C Analysis Of Phospholipid Fatty Acids And DNA Extraction

    NASA Astrophysics Data System (ADS)

    Seifert, A.; Gleixner, G.

    2008-12-01

    We investigated the degradation of black shale organic matter by microbial communities. We inoculated two columns respectively, with the fungi Schizophyllum commune, the gram-positive bacterium Pseudomonas putida and the gram-negative bacteria Streptomyces griseus and Streptomyces chartreusis. These microorganisms are known to degrade a wide variety of organic macromolecules. Additionally, we had two sets of control columns. To one set the same nutrient solution was added as to the inoculated columns and to the other set only sterile deionised water was supplied. All columns contained 1.5 kg of freshly crushed not autoclaved black shale material with a particle size of 0.63-2 mm. The columns were incubated at 28° C and 60% humidity in the dark. The aim was to investigate, which microorganisms live on black shales and if these microorganisms are able to degrade ancient organic matter. We used compound specific stable isotope measurement techniques and compound specific 14C-dating methods. After 183 days PLFAs were extracted from the columns to investigate the microbial community, furthermore we extracted on one hand total-DNA of column material and on the other hand DNA from pure cultures isolates which grew on Kinks-agar B, Starch-casein-nitrate-agar (SCN) and on complete-yeast-medium-agar (CYM). According to the PLFA analysis bacteria dominated in the columns, whereas in pure cultures more fungi were isolated. A principal component analysis revealed differences between the columns in accordance with the inoculation, but it seems that the inoculated microorganisms were replaced by the natural population. For AMS measurements palmitic acid (C 16:0) was re-isolated from total-PLFA-extract with a preparative fraction collector (PFC). Preliminary results of the study revealed that microorganisms are able to degrade black shale material and that PLFA analysis are useful methods to be combined with analysis of stable isotope and 14C measurements to study microbial

  4. Monomeric and dimeric structures analysis and spectroscopic characterization of 3,5-difluorophenylboronic acid with experimental (FT-IR, FT-Raman, 1H and 13C NMR, UV) techniques and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Karabacak, Mehmet; Kose, Etem; Atac, Ahmet; Asiri, Abdullah M.; Kurt, Mustafa

    2014-01-01

    The spectroscopic properties of 3,5-difluorophenylboronic acid (3,5-DFPBA, C6H3F2B(OH)2) were investigated by FT-IR, FT-Raman UV-Vis, 1H and 13C NMR spectroscopic techniques. FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-10 cm-1) in the solid phase and 1H and 13C NMR spectra in DMSO solution were recorded. The UV spectra that dissolved in ethanol and water were recorded in the range of 200-400 nm for each solution. The structural and spectroscopic data of the molecule have been obtained for possible three conformers from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Hydrogen-bonded dimer of title molecule, optimized by counterpoise correction, was also studied B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H⋯O hydrogen bonding have been discussed. 1H and 13C NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. The effects due to the substitutions of boric acid group and halogen were investigated. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), nonlinear optical properties (NLO) and thermodynamic features were performed.

  5. Changes in Lignin and Polysaccharide Components in 13 Cultivars of Rice Straw following Dilute Acid Pretreatment as Studied by Solution-State 2D 1H-13C NMR

    PubMed Central

    Teramura, Hiroshi; Sasaki, Kengo; Oshima, Tomoko; Aikawa, Shimpei; Matsuda, Fumio; Okamoto, Mami; Shirai, Tomokazu; Kawaguchi, Hideo; Ogino, Chiaki; Yamasaki, Masanori; Kikuchi, Jun; Kondo, Akihiko

    2015-01-01

    A renewable raw material, rice straw is pretreated for biorefinery usage. Solution-state two-dimensional (2D) 1H-13 C hetero-nuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectroscopy, was used to analyze 13 cultivars of rice straw before and after dilute acid pretreatment, to characterize general changes in the lignin and polysaccharide components. Intensities of most (15 of 16) peaks related to lignin aromatic regions, such as p-coumarate, guaiacyl, syringyl, p-hydroxyphenyl, and cinnamyl alcohol, and methoxyl, increased or remained unchanged after pretreatment. In contrast, intensities of most (11 of 13) peaks related to lignin aliphatic linkages or ferulate decreased. Decreased heterogeneity in the intensities of three peaks related to cellulose components in acid-insoluble residues resulted in similar glucose yield (0.45–0.59 g/g-dry biomass). Starch-derived components showed positive correlations (r = 0.71 to 0.96) with glucose, 5-hydroxymethylfurfural (5-HMF), and formate concentrations in the liquid hydrolysates, and negative correlations (r = –0.95 to –0.97) with xylose concentration and acid-insoluble residue yield. These results showed the fate of lignin and polysaccharide components by pretreatment, suggesting that lignin aromatic regions and cellulose components were retained in the acid insoluble residues and starch-derived components were transformed into glucose, 5-HMF, and formate in the liquid hydrolysate. PMID:26083431

  6. Quality assurance of PASADENA hyperpolarization for 13C biomolecules

    PubMed Central

    Hövener, Jan-Bernd; Chekmenev, Eduard Y.; Harris, Kent C.; Perman, William H.; Tran, Thao T.; Bhattacharya, Pratip

    2009-01-01

    Object Define MR quality assurance procedures for maximal PASADENA hyperpolarization of a biological 13C molecular imaging reagent. Materials and methods An automated PASADENA polarizer and a parahydrogen generator were installed. 13C enriched hydroxyethyl acrylate, 1-13C, 2,3,3-d3 (HEA), was converted to hyperpolarized hydroxyethyl propionate, 1-13C, 2,3,3-d3 (HEP) and fumaric acid, 1-13C, 2,3-d2 (FUM) to hyperpolarized succinic acid, 1-13C, 2,3-d2 (SUC), by reaction with parahydrogen and norbornadiene rhodium catalyst. Incremental optimization of successive steps in PASADENA was implemented. MR spectra and in vivo images of hyperpolarized 13C imaging agents were acquired at 1.5 and 4.7 T. Results Application of quality assurance (QA) criteria resulted in incremental optimization of the individual steps in PASADENA implementation. Optimal hyperpolarization of HEP of P = 20% was achieved by calibration of the NMR unit of the polarizer (B0 field strength ± 0.002 mT). Mean hyperpolarization of SUC, P = [15.3 ± 1.9]% (N = 16) in D2O, and P = [12.8 ± 3.1]% (N = 12) in H2O, was achieved every 5–8 min (range 13–20%). An in vivo 13C succinate image of a rat was produced. Conclusion PASADENA spin hyperpolarization of SUC to 15.3% in average was demonstrated (37,400 fold signal enhancement at 4.7 T). The biological fate of 13C succinate, a normally occurring cellular intermediate, might be monitored with enhanced sensitivity. PMID:19067009

  7. Distinct fungal and bacterial δ13C signatures can drive the increase in soil δ13C with depth

    NASA Astrophysics Data System (ADS)

    Kohl, Lukas; Laganièrea, Jérôme; Edwards, Kate A.; Billings, Sharon A.; Morrill, Penny L.; Van Biesen, Geert; Ziegler, Susan E.

    2015-04-01

    Soil microbial biomass is a key precursor of soil organic carbon (SOC), and the enrichment in 13C during SOC diagenesis has been purported to be driven by increasing proportions of microbially derived SOC. Yet, little is known about how the δ13C of soil microbial biomass - and by extension the δ13C of microbial inputs to SOC - vary in space, time, or with the composition of the microbial community. Phospholipid fatty acids (PLFA) can be analyzed to measure the variation of the natural abundance δ13C values of both individual groups of microorganisms and the microbial community as a whole. Here, we show how variations of δ13CPLFA within the soil profile provides insight into C fluxes in undisturbed soils and demonstrate that distinct δ13C of fungal and bacterial biomass and their relative abundance can drive the increase of bulk δ13CSOC with depth. We studied the variation in natural abundance δ13C signatures of PLFA in podzolic soil profiles from mesic boreal forests in Atlantic Canada. Samples from the organic horizons (L,F,H) and the mineral (B; top 10 cm) horizons were analyzed for δ13C values of PLFA specific to fungi, G+ bacteria, or G- bacteria as proxies for the δ13C of the biomass of these groups, and for δ13C values of PLFA produced by a wide range of microorganisms (e.g. 16:0) as a proxy for the δ13C value of microbial biomass as a whole. Results were compared to fungi:bacteria ratios (F:B) and bulk δ13CSOC values. The δ13C values of group-specific PLFA were driven by differences among source organisms, with fungal PLFA consistently depleted (2.1 to 6.4‰) relative to and G+ and G- bacterial PLFA in the same sample. All group-specific PLFA, however, exhibited nearly constant δ13C values throughout the soil profile, apparently unaffected by the over 2.8‰ increase in δ13CSOC with depth from the L to B horizons. This indicates that bulk SOC poorly represents the substrates actually consumed by soil microorganisms in situ. Instead, our

  8. Formation of carboxylic acids from alcohols and olefins in zeolite H-ZSM-5 under mild conditions via trapping of alkyl carbenium ions with carbon monoxide: An in situ {sup 13}C solid state NMR study

    SciTech Connect

    Stepanov, A.G.; Luzgin, M.V.; Romannikov, V.N.; Sidelnikov, V.N.; Zamaraev K.I.

    1996-12-01

    Using in situ {sup 13}C solid state MAS NMR (for some reagents in combination with ex situ GC-MS), it is shown that butyl alcohols and olefins (ethene, isobutene, octene-1) undergo carbonylation to form carboxylic acids (the Koch reaction) with high conversion on zeolite H-ZSM-5 at 296-373 K. The reactions proceed without application of pressurized conditions, just upon coadsorption of CO and alcohols or CO, H{sub 2}O, and olefins on zeolite. The observed Koch reaction under mild conditions provides strong evidence for the formation of alkyl carbenium ions from alcohols and olefins on the zeolites as crucial reaction intermediates. Of the family of carbenium ions, CO reacts selectively with tertiary cations to produce tertiary carboxylic acids, unless the carbonylated molecule is too large for more bulky tertiary moieties to be accommodated and carbonylated in the narrow pores of H-ZSM05. Thus, t-BuOH, i-BuOH, and isobutene produce trimethylacetic acid with high selectivity and conversion, while ethene transforms selectively into 2-methyl-2-ethyl butyric acid. Reaction of octene-1 molecules with CO and H{sub 2}O results in acids of the C{sub 8}H{sub 17}COOH and C{sub 16}H{sub 33}COOH families with predominantly linear hydrocarbon chains. The data obtained may open up new possibilities in using solid acids in organic synthesis as carbonylation catalysts under mild conditions i.e., low temperature and normal atmospheric pressure. 55 refs., 8 figs.

  9. 40 CFR 180.1262 - Sorbitol octanoate; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Sorbitol octanoate; exemption from the... Exemptions From Tolerances § 180.1262 Sorbitol octanoate; exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of sorbitol octanoate in or on...

  10. 40 CFR 180.1262 - Sorbitol octanoate; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Sorbitol octanoate; exemption from the... Exemptions From Tolerances § 180.1262 Sorbitol octanoate; exemption from the requirement of a tolerance. An exemption from the requirement of a tolerance is established for residues of sorbitol octanoate in or on...

  11. 40 CFR 180.1222 - Sucrose octanoate esters; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Sucrose octanoate esters; exemption... FOOD Exemptions From Tolerances § 180.1222 Sucrose octanoate esters; exemption from the requirement of... octanoate esters in or on all food commodities when used in accordance with good agricultural practices....

  12. 40 CFR 180.1222 - Sucrose octanoate esters; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Sucrose octanoate esters; exemption... FOOD Exemptions From Tolerances § 180.1222 Sucrose octanoate esters; exemption from the requirement of... octanoate esters in or on all food commodities when used in accordance with good agricultural practices....

  13. Study of Urban environmental quality through Isotopes δ13C

    NASA Astrophysics Data System (ADS)

    González-Sosa, E.; Mastachi-Loza, C.; Becerril-Piña, R.; Ramos-Salinas, N. M.

    2012-04-01

    Usually, trees with similar pH values on their bark develop epiphytes of similar species, the acidity to be a factor for growth. The aim of the study was evaluate the air quality through isotope δ13C in order to define the levels of environmental quality in the city of Queretaro, Mexico. In this work were collected at least 4 epiphytes positioned in trees of the species Prosopis Laevigata at 25 sites of Queretaro City. The samples were analyzed for trace elements with an inductively coupled plasma atomic emission spectroscopy (ICP). The collecting took place during dry period, in May and early rain June 2011 period, and on four sectors to identify the spatial distribution of pollution, using isotopic analysis of concentration of δ 13C. According with the results there are significant differences among the species in each of the sampled areas. The 5 February Avenue presented greater diversity and richness of δ13C, followed by those who were surveyed in the proximity of the UAQ and finally in the middle-east area. An average value of δ13C-17.92%, followed by those surveyed in the vicinity of the UAQ that correspond to sector I and II with an concentration of δ13C-17.55% and δ13C-17.22%, and finally the samples collected in trees scattered in the East-Sector II and IV with a value of δ13C-17.02% and δ13C-15.62%, respectively. Also were observed differences between the dry and wet period. It is likely that these results of δ 13C in moist period reflect the drag of the isotopes due to rain events that could mark a trend in the dilution of this element, however there is a trend in terms of abundance and composition of finding more impact in those species sampled in dry period, in May and early June 2011.

  14. Strategy for Enhancement of (13)C-Photo-CIDNP NMR Spectra by Exploiting Fractional (13)C-Labeling of Tryptophan.

    PubMed

    Eisenreich, Wolfgang; Joshi, Monika; Illarionov, Boris; Kacprzak, Sylwia; Lukaschek, Michail; Kothe, Gerd; Budisa, Nediljko; Fischer, Markus; Bacher, Adelbert; Weber, Stefan

    2015-10-29

    The photo-CIDNP effect has proven to be useful to strongly enhance NMR signals of photochemically active proteins simply by irradiation with light. The evolving characteristic patterns of enhanced absorptive and emissive NMR lines can be exploited to elucidate the photochemistry and photophysics of light-driven protein reactions. In particular, by the assignment of (13)C NMR resonances, redox-active amino acids may be identified and thereby electron-transfer pathways unraveled, in favorable cases, even with (13)C at natural abundance. If signal enhancement is weak, uniform (13)C isotope labeling is traditionally applied to increase the signal strength of protein (13)C NMR. However, this typically leads to cross relaxation, which transfers light-induced nuclear-spin polarization to adjacent (13)C nuclei, thereby preventing an unambiguous analysis of the photo-CIDNP effect. In this contribution, two isotope labeling strategies are presented; one leads to specific but ubiquitous (13)C labeling in tryptophan, and the other is based on fractional isotope labeling affording sets of isotopologs with low probability of next-neighbor isotope accumulation within individual tryptophan molecules. Consequently, cross relaxation is largely avoided while the signal enhancement by (13)C enrichment is preserved. This results in significantly simplified polarization patterns that are easier to analyze with respect to the generation of light-generated nuclear-spin polarization. PMID:26244593

  15. Biosynthetic uniform 13C,15N-labelling of zervamicin IIB. Complete 13C and 15N NMR assignment.

    PubMed

    Ovchinnikova, Tatyana V; Shenkarev, Zakhar O; Yakimenko, Zoya A; Svishcheva, Natalia V; Tagaev, Andrey A; Skladnev, Dmitry A; Arseniev, Alexander S

    2003-01-01

    Zervamicin IIB is a member of the alpha-aminoisobutyric acid containing peptaibol antibiotics. A new procedure for the biosynthetic preparation of the uniformly 13C- and 15N-enriched peptaibol is described This compound was isolated from the biomass of the fungus-producer Emericellopsis salmosynnemata strain 336 IMI 58330 obtained upon cultivation in the totally 13C, 15N-labelled complete medium. To prepare such a medium the autolysed biomass and the exopolysaccharides of the obligate methylotrophic bacterium Methylobacillus flagellatus KT were used. This microorganism was grown in totally 13C, 15N-labelled minimal medium containing 13C-methanol and 15N-ammonium chloride as the only carbon and nitrogen sources. Preliminary NMR spectroscopic analysis indicated a high extent of isotope incorporation (> 90%) and led to the complete 13C- and 15N-NMR assignment including the stereospecific assignment of Aib residues methyl groups. The observed pattern of the structurally important secondary chemical shifts of 1H(alpha), 13C=O and 13C(alpha) agrees well with the previously determined structure of zervamicin IIB in methanol solution. PMID:14658801

  16. Measuring changes in substrate utilization in the myocardium in response to fasting using hyperpolarized [1-13C]butyrate and [1-13C]pyruvate

    PubMed Central

    Bastiaansen, Jessica A. M.; Merritt, Matthew E.; Comment, Arnaud

    2016-01-01

    Cardiac dysfunction is often associated with a shift in substrate preference for ATP production. Hyperpolarized (HP) 13C magnetic resonance spectroscopy (MRS) has the unique ability to detect real-time metabolic changes in vivo due to its high sensitivity and specificity. Here a protocol using HP [1-13C]pyruvate and [1-13C]butyrate is used to measure carbohydrate versus fatty acid metabolism in vivo. Metabolic changes in fed and fasted Sprague Dawley rats (n = 36) were studied at 9.4 T after tail vein injections. Pyruvate and butyrate competed for acetyl-CoA production, as evidenced by significant changes in [13C]bicarbonate (−48%), [1-13C]acetylcarnitine (+113%), and [5-13C]glutamate (−63%), following fasting. Butyrate uptake was unaffected by fasting, as indicated by [1-13C]butyrylcarnitine. Mitochondrial pseudoketogenesis facilitated the labeling of the ketone bodies [1-13C]acetoacetate and [1-13C]β-hydroxybutyryate, without evidence of true ketogenesis. HP [1-13C]acetoacetate was increased in fasting (250%) but decreased during pyruvate co-injection (−82%). Combining HP 13C technology and co-administration of separate imaging agents enables noninvasive and simultaneous monitoring of both fatty acid and carbohydrate oxidation. This protocol illustrates a novel method for assessing metabolic flux through different enzymatic pathways simultaneously and enables mechanistic studies of the changing myocardial energetics often associated with disease. PMID:27150735

  17. Measuring changes in substrate utilization in the myocardium in response to fasting using hyperpolarized [1-(13)C]butyrate and [1-(13)C]pyruvate.

    PubMed

    Bastiaansen, Jessica A M; Merritt, Matthew E; Comment, Arnaud

    2016-01-01

    Cardiac dysfunction is often associated with a shift in substrate preference for ATP production. Hyperpolarized (HP) (13)C magnetic resonance spectroscopy (MRS) has the unique ability to detect real-time metabolic changes in vivo due to its high sensitivity and specificity. Here a protocol using HP [1-(13)C]pyruvate and [1-(13)C]butyrate is used to measure carbohydrate versus fatty acid metabolism in vivo. Metabolic changes in fed and fasted Sprague Dawley rats (n = 36) were studied at 9.4 T after tail vein injections. Pyruvate and butyrate competed for acetyl-CoA production, as evidenced by significant changes in [(13)C]bicarbonate (-48%), [1-(13)C]acetylcarnitine (+113%), and [5-(13)C]glutamate (-63%), following fasting. Butyrate uptake was unaffected by fasting, as indicated by [1-(13)C]butyrylcarnitine. Mitochondrial pseudoketogenesis facilitated the labeling of the ketone bodies [1-(13)C]acetoacetate and [1-(13)C]β-hydroxybutyryate, without evidence of true ketogenesis. HP [1-(13)C]acetoacetate was increased in fasting (250%) but decreased during pyruvate co-injection (-82%). Combining HP (13)C technology and co-administration of separate imaging agents enables noninvasive and simultaneous monitoring of both fatty acid and carbohydrate oxidation. This protocol illustrates a novel method for assessing metabolic flux through different enzymatic pathways simultaneously and enables mechanistic studies of the changing myocardial energetics often associated with disease. PMID:27150735

  18. Hepatic gluconeogenesis influences (13)C enrichment in lactate in human brain tumors during metabolism of [1,2-(13)C]acetate.

    PubMed

    Pichumani, Kumar; Mashimo, Tomoyuki; Vemireddy, Vamsidhara; Kovacs, Zoltan; Ratnakar, James; Mickey, Bruce; Malloy, Craig R; DeBerardinis, Ralph J; Bachoo, Robert M; Maher, Elizabeth A

    2016-07-01

    (13)C-enriched compounds are readily metabolized in human malignancies. Fragments of the tumor, acquired by biopsy or surgical resection, may be acid-extracted and (13)C NMR spectroscopy of metabolites such as glutamate, glutamine, 2-hydroxyglutarate, lactate and others provide a rich source of information about tumor metabolism in situ. Recently we observed (13)C-(13)C spin-spin coupling in (13)C NMR spectra of lactate in brain tumors removed from patients who were infused with [1,2-(13)C]acetate prior to the surgery. We found, in four patients, that infusion of (13)C-enriched acetate was associated with synthesis of (13)C-enriched glucose, detectable in plasma. (13)C labeled glucose derived from [1,2-(13)C]acetate metabolism in the liver and the brain pyruvate recycling in the tumor together lead to the production of the (13)C labeled lactate pool in the brain tumor. Their combined contribution to acetate metabolism in the brain tumors was less than 4.0%, significantly lower than the direct oxidation of acetate in the citric acid cycle in tumors. PMID:27020407

  19. 13C NMR Metabolomics: INADEQUATE Network Analysis

    PubMed Central

    Clendinen, Chaevien S.; Pasquel, Christian; Ajredini, Ramadan; Edison, Arthur S.

    2015-01-01

    The many advantages of 13C NMR are often overshadowed by its intrinsically low sensitivity. Given that carbon makes up the backbone of most biologically relevant molecules, 13C NMR offers a straightforward measurement of these compounds. Two-dimensional 13C-13C correlation experiments like INADEQUATE (incredible natural abundance double quantum transfer experiment) are ideal for the structural elucidation of natural products and have great but untapped potential for metabolomics analysis. We demonstrate a new and semi-automated approach called INETA (INADEQUATE network analysis) for the untargeted analysis of INADEQUATE datasets using an in silico INADEQUATE database. We demonstrate this approach using isotopically labeled Caenorhabditis elegans mixtures. PMID:25932900

  20. Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, 13C, 1H) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 2-acetoxybenzoic acid by density functional methods

    NASA Astrophysics Data System (ADS)

    Bhavani, K.; Renuga, S.; Muthu, S.; Sankara narayanan, K.

    2015-02-01

    In this work, colorless crystals of 2-acetoxybenzoic acid were grown by slow evaporation method and the FT-IR and FT-Raman spectra of the sample were recorded in the region 4000-500 cm-1 and 4000-100 cm-1 respectively. Molecular structure is optimized with the help of density functional theory method (B3LYP) with 6-31+G(d,p), 6-311++G(d,p) basis sets. Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the σ∗ antibonding orbitals and E(2) energies confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis following the scaled quantum mechanical force field (SQMFF) methodology. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by GIAO method. Mulliken population analysis on atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule.

  1. Spectroscopic (FT-IR, FT-Raman, 1H- and 13C-NMR), theoretical and microbiological study of trans o-coumaric acid and alkali metal o-coumarates.

    PubMed

    Kowczyk-Sadowy, Małgorzata; Świsłocka, Renata; Lewandowska, Hanna; Piekut, Jolanta; Lewandowski, Włodzimierz

    2015-01-01

    This work is a continuation of research on a correlation between the molecular structure and electronic charge distribution of phenolic compounds and their biological activity. The influence of lithium, sodium, potassium, rubidium and cesium cations on the electronic system of trans o-coumaric (2-hydroxy-cinnamic) acid was studied. We investigated the relationship between the molecular structure of the tested compounds and their antimicrobial activity. Complementary molecular spectroscopic techniques such as infrared (FT-IR), Raman (FT-Raman), ultraviolet-visible (UV-VIS) and nuclear magnetic resonance (1H- and 13C-NMR) were applied. Structures of the molecules were optimized and their structural characteristics were calculated by the density functional theory (DFT) using the B3LYP method with 6-311++G** as a basis set. Geometric and magnetic aromaticity indices, atomic charges, dipole moments and energies were also calculated. Theoretical parameters were compared to the experimental characteristics of investigated compounds. Correlations between certain vibrational bands and some metal parameters, such as electronegativity, ionization energy, atomic and ionic radius, were found. The microbial activity of studied compounds was tested against Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Proteus vulgaris and Candida albicans. PMID:25689641

  2. New guidelines for δ13C measurements

    USGS Publications Warehouse

    Coplen, Tyler B.; Brand, Willi A.; Gehre, Matthias; Groning, Manfred; Meijer, Harro A. J.; Toman, Blaza; Verkouteren, R. Michael

    2006-01-01

    Consistency of δ13C measurements can be improved 39−47% by anchoring the δ13C scale with two isotopic reference materials differing substantially in 13C/12C. It is recommended thatδ13C values of both organic and inorganic materials be measured and expressed relative to VPDB (Vienna Peedee belemnite) on a scale normalized by assigning consensus values of −46.6‰ to L-SVEC lithium carbonate and +1.95‰ to NBS 19 calcium carbonate. Uncertainties of other reference material values on this scale are improved by factors up to two or more, and the values of some have been notably shifted:  the δ13C of NBS 22 oil is −30.03%.

  3. Octanoate in Human Albumin Preparations Is Detrimental to Mesenchymal Stromal Cell Culture

    PubMed Central

    Wong, Way-Wua; MacKenzie, Andrew D.; Nelson, Vicky J.; Faed, James M.; Turner, Paul R.

    2015-01-01

    Cell therapies hold great promise as the next major advance in medical treatment. To enable safe, effective ex vivo culture whilst maintaining cell phenotype, growth media constituents must be carefully controlled. We have used a chemically defined mesenchymal stromal cell culture medium to investigate the influence of different preparations of human serum albumin. We examined two aspects of cell culture, growth rate as measured by population doubling time and colony forming ability which is a representative measure of the stemness of the cell population. Albumin preparations showed comparative differences in both of these criteria. Analysis of the albumin bound fatty acids also showed differences depending on the manufacturing procedure used. We demonstrated that octanoate, an additive used to stabilize albumin during pasteurization, slows growth and lowers colony forming ability during ex vivo culture. Further to this we also found the level of Na+/K+ ATPase, a membrane bound cation pump inhibited by octanoate, is increased in cells exposed to this compound. We conclude that the inclusion of human serum albumin in ex vivo growth media requires careful consideration of not only the source of albumin, but also the associated molecular cargo, for optimal cell growth and behavior. PMID:26074972

  4. /sup 13/C spin diffusion of adamantane

    SciTech Connect

    Bronniman, C.E.; Szeverenyi, N.M.; Maciel, G.E.

    1983-10-15

    Two-dimensional exchange spectroscopy of natural abundance /sup 13/C--/sup 13/C spin diffusion in solid adamantane illustrates the influence that /sup 13/C--/sup 1/H dipole--dipole coupling exerts on /sup 13/C spin diffusion by determining spectral overlap in the /sup 13/C system. 2D /sup 13/C spectra were obtained for several values of mixing time tau/sub m/ and compared with spectra calculated in the limit of nearest-neighbor coupling. Good agreement is obtained for short tau/sub m/, during which the equilibration of neighboring spins dominates. For longer tau/sub m/, slower spin diffusion that is not acounted for by the simple model is seen; after nearest-neighbor spins equilibrate, communication over larger distances produces further mixing. It is possible to modify spin diffusion rates by altering experimental conditions, e.g., magic-angle spinning, low-power /sup 1/H decoupling, or spin locking /sup 13/C in the rotating frame during tau/sub m/.

  5. Experimental (X-ray, (13)C CP/MAS NMR, IR, RS, INS, THz) and Solid-State DFT Study on (1:1) Co-Crystal of Bromanilic Acid and 2,6-Dimethylpyrazine.

    PubMed

    Łuczyńska, Katarzyna; Drużbicki, Kacper; Lyczko, Krzysztof; Dobrowolski, Jan Cz

    2015-06-01

    A combined structural, vibrational spectroscopy, and solid-state DFT study of the hydrogen-bonded complex of bromanilic acid with 2,6-dimethylpyrazine is reported. The crystallographic structure was determined by means of low-temperature single-crystal X-ray diffraction, which reveals the molecular units in their native protonation states, forming one-dimensional infinite nets of moderate-strength O···H-N hydrogen bonds. The nature of the crystallographic forces, stabilizing the studied structure, has been drawn by employing the noncovalent interactions analysis. It was found that, in addition to the hydrogen bonding, the intermolecular forces are dominated by stacking interactions and C-H···O contacts. The thermal and calorimetric analysis was employed to probe stability of the crystal phase. The structural analysis was further supported by a computationally assisted (13)C CP/MAS NMR study, providing a complete assignment of the recorded resonances. The vibrational dynamics was explored by combining the optical (IR, Raman, TDs-THz) and inelastic neutron scattering (INS) spectroscopy techniques with the state-of-the-art solid-state density functional theory (DFT) computations. Despite the quasi-harmonic approximation assumed throughout the study, an excellent agreement between the theoretical and experimental data was achieved over the entire spectral range, allowing for a deep and possibly thorough understanding of the vibrational characteristics of the system. Particularly, the significant influence of the long-range dipole coupling on the IR spectrum has been revealed. On the basis of a wealth of information gathered, the recent implementation of a dispersion-corrected linear-response scheme has been extensively examined. PMID:25961154

  6. Synthesis and applications of {sup 13}C glycerol

    SciTech Connect

    Stocking, E.; Khalsa, O.; Martinez, R.A.; Silks, L.A. III

    1994-12-01

    Due in part to the use of labeled glycerol for the {sup 13}C enrichment of biomolecules, we are currently developing new synthetic routes to various isotopomers of glycerol. Judging from our experience, traditional methods of glycerol synthesis are not easily adapted for isotopic enrichment and/or have poor overall yields (12 to 15%). Furthermore, the use of glycerol for enrichment can be prohibitively expensive and its availability is limited by the level of demand. We are presently developing a short de novo synthesis of glycerol from carbon dioxide ({approximately}53% overall yield for four steps) and are examining the feasibility of synthesizing site-specific {sup 13}C-labeled glycerol and dihydroxyacetone (DHA) from labeled methanol and carbon dioxide. One application of {sup 13}C glycerol we have examined is enzymatic conversion of glycerol to glyceraldehyde-3-monophosphate or dihydroxyacetone monophosphate (DHAP) with yields ranging from 25 to 50% (as determined by NMR spectroscopy). We are also pursuing the chemical conversion of {sup 13}C-labeled DHA to DHAP. We are especially interested in {sup 13}C-labeled DHAP because we are investigating its use as a chemo-enzymatic precursor for both labeled 2-deoxyribose and 2-deoxyribonucleic acids.

  7. In vivo13C spectroscopy in the rat brain using hyperpolarized [1- 13C]pyruvate and [2- 13C]pyruvate

    NASA Astrophysics Data System (ADS)

    Marjańska, Małgorzata; Iltis, Isabelle; Shestov, Alexander A.; Deelchand, Dinesh K.; Nelson, Christopher; Uğurbil, Kâmil; Henry, Pierre-Gilles

    2010-10-01

    The low sensitivity of 13C spectroscopy can be enhanced using dynamic nuclear polarization. Detection of hyperpolarized [1- 13C]pyruvate and its metabolic products has been reported in kidney, liver, and muscle. In this work, the feasibility of measuring 13C signals of hyperpolarized 13C metabolic products in the rat brain in vivo following the injection of hyperpolarized [1- 13C]pyruvate and [2- 13C]pyruvate is investigated. Injection of [2- 13C]pyruvate led to the detection of [2- 13C]lactate, but no other downstream metabolites such as TCA cycle intermediates were detected. Injection of [1- 13C]pyruvate enabled the detection of both [1- 13C]lactate and [ 13C]bicarbonate. A metabolic model was used to fit the hyperpolarized 13C time courses obtained during infusion of [1- 13C]pyruvate and to determine the values of VPDH and VLDH.

  8. Two-dimensional (13)C-(13)C correlation spectroscopy with magic angle spinning and dynamic nuclear polarization.

    PubMed

    Rosay, Melanie; Weis, Volker; Kreischer, Kenneth E; Temkin, Richard J; Griffin, Robert G

    2002-04-01

    The sensitivity of solid-state NMR experiments can be enhanced with dynamic nuclear polarization (DNP), a technique that transfers the high Boltzmann polarization of unpaired electrons to nuclei. Signal enhancements of up to 23 have been obtained for magic angle spinning (MAS) experiments at 5 T and 85-90 K using a custom-designed high-power gyrotron. The extended stability of MAS/DNP experiments at low temperature is demonstrated with (1)H-driven (13)C spin-diffusion experiments on the amino acid proline. These (13)C-(13)C chemical shift correlation spectra are the first two-dimensional MAS/DNP experiments performed at high field (>1.4 T). PMID:11916398

  9. Transport and imaging of brute-force (13)C hyperpolarization.

    PubMed

    Hirsch, Matthew L; Smith, Bryce A; Mattingly, Mark; Goloshevsky, Artem G; Rosay, Melanie; Kempf, James G

    2015-12-01

    We demonstrate transport of hyperpolarized frozen 1-(13)C pyruvic acid from its site of production to a nearby facility, where a time series of (13)C images was acquired from the aqueous dissolution product. Transportability is tied to the hyperpolarization (HP) method we employ, which omits radical electron species used in other approaches that would otherwise relax away the HP before reaching the imaging center. In particular, we attained (13)C HP by 'brute-force', i.e., using only low temperature and high-field (e.g., T<∼2K and B∼14T) to pre-polarize protons to a large Boltzmann value (∼0.4% (1)H polarization). After polarizing the neat, frozen sample, ejection quickly (<1s) passed it through a low field (B<100G) to establish the (1)H pre-polarization spin temperature on (13)C via the process known as low-field thermal mixing (yielding ∼0.1% (13)C polarization). By avoiding polarization agents (a.k.a. relaxation agents) that are needed to hyperpolarize by the competing method of dissolution dynamic nuclear polarization (d-DNP), the (13)C relaxation time was sufficient to transport the sample for ∼10min before finally dissolving in warm water and obtaining a (13)C image of the hyperpolarized, dilute, aqueous product (∼0.01% (13)C polarization, a >100-fold gain over thermal signals in the 1T scanner). An annealing step, prior to polarizing the sample, was also key for increasing T1∼30-fold during transport. In that time, HP was maintained using only modest cryogenics and field (T∼60K and B=1.3T), for T1((13)C) near 5min. Much greater time and distance (with much smaller losses) may be covered using more-complete annealing and only slight improvements on transport conditions (e.g., yielding T1∼5h at 30K, 2T), whereas even intercity transfer is possible (T1>20h) at reasonable conditions of 6K and 2T. Finally, it is possible to increase the overall enhancement near d-DNP levels (i.e., 10(2)-fold more) by polarizing below 100mK, where nanoparticle

  10. Transport and imaging of brute-force 13C hyperpolarization

    NASA Astrophysics Data System (ADS)

    Hirsch, Matthew L.; Smith, Bryce A.; Mattingly, Mark; Goloshevsky, Artem G.; Rosay, Melanie; Kempf, James G.

    2015-12-01

    We demonstrate transport of hyperpolarized frozen 1-13C pyruvic acid from its site of production to a nearby facility, where a time series of 13C images was acquired from the aqueous dissolution product. Transportability is tied to the hyperpolarization (HP) method we employ, which omits radical electron species used in other approaches that would otherwise relax away the HP before reaching the imaging center. In particular, we attained 13C HP by 'brute-force', i.e., using only low temperature and high-field (e.g., T < ∼2 K and B ∼ 14 T) to pre-polarize protons to a large Boltzmann value (∼0.4% 1H polarization). After polarizing the neat, frozen sample, ejection quickly (<1 s) passed it through a low field (B < 100 G) to establish the 1H pre-polarization spin temperature on 13C via the process known as low-field thermal mixing (yielding ∼0.1% 13C polarization). By avoiding polarization agents (a.k.a. relaxation agents) that are needed to hyperpolarize by the competing method of dissolution dynamic nuclear polarization (d-DNP), the 13C relaxation time was sufficient to transport the sample for ∼10 min before finally dissolving in warm water and obtaining a 13C image of the hyperpolarized, dilute, aqueous product (∼0.01% 13C polarization, a >100-fold gain over thermal signals in the 1 T scanner). An annealing step, prior to polarizing the sample, was also key for increasing T1 ∼ 30-fold during transport. In that time, HP was maintained using only modest cryogenics and field (T ∼ 60 K and B = 1.3 T), for T1(13C) near 5 min. Much greater time and distance (with much smaller losses) may be covered using more-complete annealing and only slight improvements on transport conditions (e.g., yielding T1 ∼ 5 h at 30 K, 2 T), whereas even intercity transfer is possible (T1 > 20 h) at reasonable conditions of 6 K and 2 T. Finally, it is possible to increase the overall enhancement near d-DNP levels (i.e., 102-fold more) by polarizing below 100 mK, where

  11. Characterization of actions of octanoate on porcine preadipocytes and adipocytes differentiated in vitro

    SciTech Connect

    Suzuki, Shunichi; Suzuki, Misae; Sembon, Shoichiro; Fuchimoto, Daiichiro; Onishi, Akira

    2013-03-01

    Highlights: ► Octanoate regulated gene expressions in a way distinct from rosiglitasone. ► Octanoate upregulatedPPRE and LXRE reporter activities. ► Octanoate may act on some PPARγ-target genes competitively with other ligands. - Abstract: Octanoate is used to induce adipogenic differentiation and/or lipid accumulation in preadipocytes of domestic animals. However, information on detailed actions of octanoate and the characteristics of octanoate-induced adipocytes is limited. The aim of this study was to examine these issues by comparing the outcomes of the effects of octanoate with those of rosiglitazone, which is a well-defined activator of peroxisome proliferator-activated receptor (PPAR)-γ. The adipocytes that were differentiated with 5 mM of octanoate had dispersed and diversely sized lipid droplets compared to those that were differentiated with 1 μM of rosiglitazone. The gene expression levels of adiponectin, glycerol-3-phosphate dehydrogenase, perilipin 1, and perilipin 4 were much higher in the adipocytes that were differentiated with rosiglitazone than in those differentiated with octanoate, while the gene expression levels of lipoprotein lipase and perilipin 2 were decreased in rosiglitazone-differentiated adipocytes compared to octanoate-differentiated adipocytes. However, the expressions of aP2 and CD36 genes were comparably induced. Luciferase reporter assays revealed that PPAR and liver-X-receptor activities were upregulated by octanoate more effectively than by rosiglitazone. Overall, these results suggested that the action of octanoate was complicated and may be dependent on the targeted genes and cellular status.

  12. Synthesis of 2-deoxy-(6-/sup 13/C)glucose

    SciTech Connect

    Walker, T.E.; Unkefer, C.J.; Ehler, D.S.

    1987-05-01

    The authors have prepared 2-deoxy-D-(6-/sup 13/C)glucose which will be used to test the stability of 2-deoxy-D-glucose-6-phosphate in brain tissue. They chose to label 2-deoxy-D-glucose at C-6 because of the large chemical shift difference between C-6 in the free sugar and C-6 in the 6-phosphate analog. Their synthetic scheme is similar to that used for the synthesis of D-(6-/sup 13/C)glucose which involves the removal of C-6 from D-glucose followed by its replacement with /sup 13/C. They first prepare the methyl ..cap alpha..-furanoside using trifluoroacetic acid in methanol. This product is then treated with periodate which cleaves only between C-5 and C-6 to form a hydrated aldehyde which is reacted directly with K/sup 13/CN to form a mixture of nitriles. The enriched nitriles are reduced with hydrogen to a mixture of 6-aldehydo sugars using a 5% Pd on carbon catalyst. These sugars are reduced with NaBH/sub 4/ to a mixture of labeled methyl furanosides. Acid hydrolysis followed by chromatography yields 2-deoxy-D-(6-/sup 13/C)glucose in an overall yield of 10% from K/sup 13/CN.

  13. Characterization of actions of octanoate on porcine preadipocytes and adipocytes differentiated in vitro.

    PubMed

    Suzuki, Shunichi; Suzuki, Misae; Sembon, Shoichiro; Fuchimoto, Daiichiro; Onishi, Akira

    2013-03-01

    Octanoate is used to induce adipogenic differentiation and/or lipid accumulation in preadipocytes of domestic animals. However, information on detailed actions of octanoate and the characteristics of octanoate-induced adipocytes is limited. The aim of this study was to examine these issues by comparing the outcomes of the effects of octanoate with those of rosiglitazone, which is a well-defined activator of peroxisome proliferator-activated receptor (PPAR)-γ. The adipocytes that were differentiated with 5mM of octanoate had dispersed and diversely sized lipid droplets compared to those that were differentiated with 1 μM of rosiglitazone. The gene expression levels of adiponectin, glycerol-3-phosphate dehydrogenase, perilipin 1, and perilipin 4 were much higher in the adipocytes that were differentiated with rosiglitazone than in those differentiated with octanoate, while the gene expression levels of lipoprotein lipase and perilipin 2 were decreased in rosiglitazone-differentiated adipocytes compared to octanoate-differentiated adipocytes. However, the expressions of aP2 and CD36 genes were comparably induced. Luciferase reporter assays revealed that PPAR and liver-X-receptor activities were upregulated by octanoate more effectively than by rosiglitazone. Overall, these results suggested that the action of octanoate was complicated and may be dependent on the targeted genes and cellular status. PMID:23376076

  14. Adult-onset hypothyroidism and the cerebral metabolism of (1,2-13C2) acetate as detected by 13C nuclear magnetic resonance.

    PubMed

    Chapa, F; Künnecke, B; Calvo, R; Escobar del Rey, F; Morreale de Escobar, G; Cerdán, S

    1995-01-01

    The effects of adult-onset hypothyroidism on the metabolic compartmentation of the cerebral tricarboxylic acid cycle and the gamma-aminobutyric acid (GABA) shunt have been investigated by 13C nuclear magnetic resonance spectroscopy. Rats thyroidectomized as adults and age-matched controls were infused in the right jugular vein with unlabeled or (1,2-13C2) acetate solutions for 60 min. At the end of the infusion, the brains were frozen in situ and perchloric acid extracts were prepared and analyzed by 13C nuclear magnetic resonance and reverse-phase HPLC. Thyroidectomized animals showed a decrease in the incorporation of 13C from (1,2-13C2) acetate in cerebral metabolites and an increase in the concentrations of unlabeled glutamate and GABA. Computer-assisted interpretation of the 13C multiplets observed for the carbons of glutamate, glutamine, and GABA indicated that adult-onset hypothyroidism produced 1) a decrease in the contribution of infused (1,2-13C2) acetate to the glial tricarboxylic acid cycle; 2) an increase in the contribution of unlabeled acetyl-CoA to the neuronal tricarboxylic acid cycle; and 3) impairments in the exchange of glutamate, glutamine, and GABA between the neuronal and glial compartments. Despite the fact that the adult brain has often been considered metabolically unresponsive to thyroid hormone status, present results show metabolic alterations in the neuronal and glial compartments that are reversible with substitution therapy. PMID:7828544

  15. Synthesis of isotopically labeled R- or S-[.sup.13C, .sup.2H] glycerols

    DOEpatents

    Martinez, Rodolfo A.; Unkefer, Clifford J.; Alvarez, Marc A.

    2008-01-22

    The present invention is directed to asymmetric chiral labeled glycerols including at least one chiral atom, from one to two .sup.13C atoms and from zero to four deuterium atoms bonded directly to a carbon atom, e.g., (2S) [1,2-.sup.13C.sub.2]glycerol and (2R) [1,2-.sup.13C.sub.2]glycerol, and to the use of such chiral glycerols in the preparation of labeled amino acids.

  16. Analysing Groundwater Using the 13C Isotope

    NASA Astrophysics Data System (ADS)

    Awad, Sadek

    The stable isotope of the carbon atom (13C) give information about the type of the mineralisation of the groundwater existing during the water seepage and about the recharge conditions of the groundwater. The concentration of the CO2(aq.) dissolved during the infiltration of the water through the soil's layers has an effect on the mineralisation of this water. The type of the photosynthesis's cycle (C-3 or C-4 carbon cycle) can have a very important role to determine the conditions (closed or open system) of the mineralisation of groundwater. The isotope 13C of the dissolved CO2 in water give us a certain information about the origin and the area of pollution of water. The proportion of the biogenic carbon and its percentage in the mineralisation of groundwater is determined by using the isotope 13C.

  17. States of 13C with abnormal radii

    NASA Astrophysics Data System (ADS)

    Demyanova, A. S.; Ogloblin, A. A.; Danilov, A. N.; Goncharov, S. A.; Belyaeva, T. L.; Sobolev, Yu. G.; Khlebnikov, S. V.; Burtebaev, N.; Trzaska, W.; Heikkinen, P.; Tyurin, G. P.; Janseitov, D.; Gurov, Yu. B.

    2016-05-01

    Differential cross-sections of the elastic and inelastic 13C + α scattering were measured at E(α) = 90 MeV. The root mean-square radii() of 13C nucleus in the states: 8.86 (1/2-), 3.09 (1/2+) and 9.90 (3/2-) MeV were determined by the Modified diffraction model (MDM). The radii of the first two levels are enhanced compared to that of the ground state of 13C, confirming the suggestion that the 8.86 MeV state is an analogue of the Hoyle state in 12C and the 3.09 MeV state has a neutron halo. Some indications to the abnormally small size of the 9.90 MeV state were obtained.

  18. Synthesis Of [2h, 13c] And [2h3, 13c]Methyl Aryl Sulfides

    DOEpatents

    Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.

    2004-03-30

    The present invention is directed to labeled compounds, [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2, .sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfides wherein the .sup.13 C methyl group attached to the sulfur of the sulfide includes exactly one, two or three deuterium atoms and the aryl group is selected from the group consisting of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, and R.sub.5 are each independently, hydrogen, a C.sub.1 -C.sub.4 lower alkyl, a halogen, an amino group from the group consisting of NH.sub.2, NHR and NRR' where R and R' are each a C.sub.1 -C.sub.4 lower alkyl, a phenyl, or an alkoxy group. The present invention is also directed to processes of preparing [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2,.sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfides wherein the .sup.13 C methyl group attached to the sulfur of the sulfide includes exactly one, two or three deuterium atoms. The present invention is also directed to the labeled compounds of [.sup.2 H.sub.1, .sup.13 C]methyl iodide and [.sup.2 H.sub.2, .sup.13 C]methyl iodide.

  19. Accurate determinations of one-bond 13C-13C couplings in 13C-labeled carbohydrates

    NASA Astrophysics Data System (ADS)

    Azurmendi, Hugo F.; Freedberg, Darón I.

    2013-03-01

    Carbon plays a central role in the molecular architecture of carbohydrates, yet the availability of accurate methods for 1DCC determination has not been sufficiently explored, despite the importance that such data could play in structural studies of oligo- and polysaccharides. Existing methods require fitting intensity ratios of cross- to diagonal-peaks as a function of the constant-time (CT) in CT-COSY experiments, while other methods utilize measurement of peak separation. The former strategies suffer from complications due to peak overlap, primarily in regions close to the diagonal, while the latter strategies are negatively impacted by the common occurrence of strong coupling in sugars, which requires a reliable assessment of their influence in the context of RDC determination. We detail a 13C-13C CT-COSY method that combines a variation in the CT processed with diagonal filtering to yield 1JCC and RDCs. The strategy, which relies solely on cross-peak intensity modulation, is inspired in the cross-peak nulling method used for JHH determinations, but adapted and extended to applications where, like in sugars, large one-bond 13C-13C couplings coexist with relatively small long-range couplings. Because diagonal peaks are not utilized, overlap problems are greatly alleviated. Thus, one-bond couplings can be determined from different cross-peaks as either active or passive coupling. This results in increased accuracy when more than one determination is available, and in more opportunities to measure a specific coupling in the presence of severe overlap. In addition, we evaluate the influence of strong couplings on the determination of RDCs by computer simulations. We show that individual scalar couplings are notably affected by the presence of strong couplings but, at least for the simple cases studied, the obtained RDC values for use in structural calculations were not, because the errors introduced by strong couplings for the isotropic and oriented phases are very

  20. 13C-DEPLETED MICROBIAL LIPIDS INDICATE SEASONAL METHANOTROPHIC ACTIVITY IN SHALLOW ESTUARINE SEDIMENTS

    EPA Science Inventory

    Compound specific isotope analysis was combined with phospholipid fatty acid (PLFA) analysis to identify methanotrophic activity in members of the sedimentary microbial community in the Altamaha and Savannah River estuaries in Georgia. 13C-depleted PLFAs indicate methane utilizat...

  1. Optoacoustic 13C-breath test analyzer

    NASA Astrophysics Data System (ADS)

    Harde, Hermann; Helmrich, Günther; Wolff, Marcus

    2010-02-01

    The composition and concentration of exhaled volatile gases reflects the physical ability of a patient. Therefore, a breath analysis allows to recognize an infectious disease in an organ or even to identify a tumor. One of the most prominent breath tests is the 13C-urea-breath test, applied to ascertain the presence of the bacterium helicobacter pylori in the stomach wall as an indication of a gastric ulcer. In this contribution we present a new optical analyzer that employs a compact and simple set-up based on photoacoustic spectroscopy. It consists of two identical photoacoustic cells containing two breath samples, one taken before and one after capturing an isotope-marked substrate, where the most common isotope 12C is replaced to a large extent by 13C. The analyzer measures simultaneously the relative CO2 isotopologue concentrations in both samples by exciting the molecules on specially selected absorption lines with a semiconductor laser operating at a wavelength of 2.744 μm. For a reliable diagnosis changes of the 13CO2 concentration of 1% in the exhaled breath have to be detected at a concentration level of this isotope in the breath of about 500 ppm.

  2. Preliminary studies of a canine 13C-aminopyrine demethylation blood test.

    PubMed Central

    Moeller, E M; Steiner, J M; Williams, D A; Klein, P D

    2001-01-01

    The objectives of this study were to determine whether a 13C-aminopyrine demethylation blood test is technically feasible in clinically healthy dogs, whether oral administration of 13C-aminopyrine causes a detectable increase in percent dose/min (PCD) of 13C administered as 13C-aminopyrine and recovered in gas extracted from blood, and whether gas extraction efficiency has an impact on PCD. A dose of 2 mg/kg body weight of 13C-aminopyrine dissolved in deionized water was administered orally to 6 clinically healthy dogs. Blood samples were taken from each dog 0, 30, 60, and 120 min after administration of the 13C-aminopyrine. Carbon dioxide was extracted from blood samples by addition of acid and analyzed by fractional mass spectrometry. None of the 6 dogs showed any side effects after 13C-aminopyrine administration. All 6 dogs showed a measurable increase of the PCD in gas samples extracted from blood samples at 30 min, 60 min, and 120 min after 13C-aminopyrine administration. Coefficients of variation between the triplicate samples were statistically significantly higher for the %CO2, a measure of extraction efficiency, than for PCD values (P < 0.0001). The 13C-aminopyrine demethylation blood test described here is technically feasible. Oral administration of 13C-aminopyrine did not lead to gross side effects in the 6 dogs. Clinically healthy dogs show a measurable increase of PCD in gas extracted from blood samples after oral administration of 13C-aminopyrine. Efficiency of CO2 extraction from blood samples does not have an impact on PCD determined from these blood samples. This test may prove useful to evaluate hepatic function in dogs. PMID:11227194

  3. Characterization of the International Humic Substances Society standard and reference fulvic and humic acids by solution state carbon-13 (13C) and hydrogen-1 (1H) nuclear magnetic resonance spectrometry

    USGS Publications Warehouse

    Thorn, Kevin A.; Folan, Daniel W.; MacCarthy, Patrick

    1989-01-01

    Standard and reference samples of the International Humic Substances Society have been characterized by solution state carbon-13 and hydrogen-1 nuclear magnetic resonance (NMR) spectrometry. Samples included the Suwannee River, soil, and peat standard fulvic and humic acids, the Leonardite standard humic acid, the Nordic aquatic reference fulvic and humic acids, and the Summit Hill soil reference humic acid. Aqueous-solution carbon-13 NMR analyses included the measurement of spin-lattice relaxation times, measurement of nuclear Overhauser enhancement factors, measurement of quantitative carbon distributions, recording of attached proton test spectra, and recording of spectra under nonquantitative conditions. Distortionless enhancement by polarization transfer carbon-13 NMR spectra also were recorded on the Suwannee River fulvic acid in deuterated dimethyl sulfoxide. Hydrogen-1 NMR spectra were recorded on sodium salts of the samples in deuterium oxide. The carbon aromaticities of the samples ranged from 0.24 for the Suwannee River fulvic acid to 0.58 for the Leonardite humic acid.

  4. Refined Analysis of Brain Energy Metabolism Using In Vivo Dynamic Enrichment of 13C Multiplets

    PubMed Central

    Dehghani M., Masoumeh; Duarte, João M. N.; Kunz, Nicolas; Gruetter, Rolf

    2016-01-01

    Carbon-13 nuclear magnetic resonance spectroscopy in combination with the infusion of 13C-labeled precursors is a unique approach to study in vivo brain energy metabolism. Incorporating the maximum information available from in vivo localized 13C spectra is of importance to get broader knowledge on cerebral metabolic pathways. Metabolic rates can be quantitatively determined from the rate of 13C incorporation into amino acid neurotransmitters such as glutamate and glutamine using suitable mathematical models. The time course of multiplets arising from 13C-13C coupling between adjacent carbon atoms was expected to provide additional information for metabolic modeling leading to potential improvements in the estimation of metabolic parameters. The aim of the present study was to extend two-compartment neuronal/glial modeling to include dynamics of 13C isotopomers available from fine structure multiplets in 13C spectra of glutamate and glutamine measured in vivo in rats brain at 14.1 T, termed bonded cumomer approach. Incorporating the labeling time courses of 13C multiplets of glutamate and glutamine resulted in elevated precision of the estimated fluxes in rat brain as well as reduced correlations between them. PMID:26969691

  5. Towards hyperpolarized 13C-succinate imaging of brain cancer

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Pratip; Chekmenev, Eduard Y.; Perman, William H.; Harris, Kent C.; Lin, Alexander P.; Norton, Valerie A.; Tan, Chou T.; Ross, Brian D.; Weitekamp, Daniel P.

    2007-05-01

    We describe a novel 13C enriched precursor molecule, sodium 1- 13C acetylenedicarboxylate, which after hydrogenation by PASADENA (Parahydrogen and Synthesis Allows Dramatically Enhanced Nuclear Alignment) under controlled experimental conditions, becomes hyperpolarized 13C sodium succinate. Fast in vivo 3D FIESTA MR imaging demonstrated that, following carotid arterial injection, the hyperpolarized 13C-succinate appeared in the head and cerebral circulation of normal and tumor-bearing rats. At this time, no in vivo hyperpolarized signal has been localized to normal brain or brain tumor. On the other hand, ex vivo samples of brain harvested from rats bearing a 9L brain tumor, 1 h or more following in vivo carotid injection of hyperpolarized 13C sodium succinate, contained significant concentrations of the injected substrate, 13C sodium succinate, together with 13C maleate and succinate metabolites 1- 13C-glutamate, 5- 13C-glutamate, 1- 13C-glutamine and 5- 13C-glutamine. The 13C substrates and products were below the limits of NMR detection in ex vivo samples of normal brain consistent with an intact blood-brain barrier. These ex vivo results indicate that hyperpolarized 13C sodium succinate may become a useful tool for rapid in vivo identification of brain tumors, providing novel biomarkers in 13C MR spectral-spatial images.

  6. Conditions to obtain precise and true measurements of the intramolecular 13C distribution in organic molecules by isotopic 13C nuclear magnetic resonance spectrometry.

    PubMed

    Bayle, Kevin; Gilbert, Alexis; Julien, Maxime; Yamada, Keita; Silvestre, Virginie; Robins, Richard J; Akoka, Serge; Yoshida, Naohiro; Remaud, Gérald S

    2014-10-10

    Intramolecular (13)C composition gives access to new information on the (bio) synthetic history of a given molecule. Isotopic (13)C NMR spectrometry provides a general tool for measuring the position-specific (13)C content. As an emerging technique, some aspects of its performance are not yet fully delineated. This paper reports on (i) the conditions required to obtain satisfactory trueness and precision for the determination of the internal (13)C distribution, and (ii) an approach to determining the "absolute" position-specific (13)C content. In relation to (i), a precision of <1% can be obtained whatever the molecule on any spectrometer, once quantitative conditions are met, in particular appropriate proton decoupling efficiency. This performance is a prerequisite to the measurement of isotope fractionation either on the transformed or residual compound when a chemical reaction or process is being studied. The study of the trueness has revealed that the response of the spectrometer depends on the (13)C frequency range of the studied molecule, i.e. the chemical shift range. The "absolute value" and, therefore, the trueness of the (13)C NMR measurements has been assessed on acetic acid and by comparison to the results obtained on the fragments from COOH and CH3 by isotopic mass spectrometry coupled to a pyrolysis device (GC-Py-irm-MS), this technique being the reference method for acetic acid. Of the two NMR spectrometers used in this work, one gave values that corresponded to those obtained by GC-Py-irm-MS (thus, the "true" value) while the other showed a bias, which was dependent to the range covered by the resonance frequencies of the molecule. Therefore, the former can be used directly for studying isotope affiliations, while the latter can only be used directly for comparative data, for example in authenticity studies, but can also be used to obtain the true values by applying appropriate correction factors. The present study assesses several key protocol

  7. Synthesis Of 2h- And 13c-Substituted Dithanes

    DOEpatents

    Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.

    2004-05-04

    The present invention is directed to labeled compounds, [2-.sup.13 C]dithane wherein the .sup.13 C atom is directly bonded to one or two deuterium atoms. The present invention is also directed to processes of preparing [2-.sup.13 C]dithane wherein the .sup.13 C atom is directly bonded to one or two deuterium atoms. The present invention is also directed to labeled compounds, e.g., [.sup.2 H.sub.1-2, .sup.13 C]methanol (arylthio)-, acetates wherein the .sup.13 C atom is directly bonded to exactly one or two deuterium atoms.

  8. Synthesis of 2H- and 13C-substituted dithanes

    DOEpatents

    Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.

    2003-01-01

    The present invention is directed to labeled compounds, [2-.sup.13 C]dithiane wherein the .sup.13 C atom is directly bonded to one or two deuterium atoms. The present invention is also directed to processes of preparing [2-.sup.13 C]dithiane wherein the .sup.13 C atom is directly bonded to one or two deuterium atoms. The present invention is also directed to labeled compounds, e.g., [.sup.2 H.sub.1-2, .sup.13 C]methanol (arylthio)-, acetates wherein the .sup.13 C atom is directly bonded to exactly one or two deuterium atoms.

  9. Dipolar-coupling-mediated total correlation spectroscopy in solid-state 13C NMR: Selection of individual 13C- 13C dipolar interactions

    NASA Astrophysics Data System (ADS)

    Spano, Justin; Wi, Sungsool

    2010-06-01

    Herein is described a useful approach in solid-state NMR, for selecting homonuclear 13C- 13C spin pairs in a multiple- 13C homonuclear dipolar coupled spin system. This method builds upon the zero-quantum (ZQ) dipolar recoupling method introduced by Levitt and coworkers (Marin-Montesinos et al., 2006 [30]) by extending the originally introduced one-dimensional (1D) experiment into a two-dimensional (2D) method with selective irradiation scheme, while moving the 13C- 13C mixing scheme from the transverse to the longitudinal mode, together with a dramatic improvement in the proton decoupling efficiency. Selective spin-pair recoupling experiments incorporating Gaussian and cosine-modulated Gaussian pulses for inverting specific spins were performed, demonstrating the ability to detect informative, simplified/individualized, long-range 13C- 13C homonuclear dipolar coupling interactions more accurately by removing less informative, stronger, short-range 13C- 13C interactions from 2D correlation spectra. The capability of this new approach was demonstrated experimentally on uniformly 13C-labeled Glutamine and a tripeptide sample, GAL.

  10. In vivo dynamic turnover of cerebral 13C isotopomers from [U- 13C]glucose

    NASA Astrophysics Data System (ADS)

    Xu, Su; Shen, Jun

    2006-10-01

    An INEPT-based 13C MRS method and a cost-effective and widely available 11.7 Tesla 89-mm bore vertical magnet were used to detect dynamic 13C isotopomer turnover from intravenously infused [U- 13C]glucose in a 211 μL voxel located in the adult rat brain. The INEPT-based 1H → 13C polarization transfer method is mostly adiabatic and therefore minimizes signal loss due to B 1 inhomogeneity of the surface coils used. High quality and reproducible data were acquired as a result of combined use of outer volume suppression, ISIS, and the single-shot three-dimensional localization scheme built in the INEPT pulse sequence. Isotopomer patterns of both glutamate C4 at 34.00 ppm and glutamine C4 at 31.38 ppm are dominated first by a doublet originated from labeling at C4 and C5 but not at C3 (with 1JC4C5 = 51 Hz) and then by a quartet originated from labeling at C3, C4, and C5 (with 1JC3C4 = 35 Hz). A lag in the transition of glutamine C4 pattern from doublet-dominance to quartet dominance as compared to glutamate C4 was observed, which provides an independent verification of the precursor-product relationship between neuronal glutamate and glial glutamine and a significant intercompartmental cerebral glutamate-glutamine cycle between neurons and glial cells.

  11. Calculation of total meal d13C from individual food d13C.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Variations in the isotopic signature of carbon in biological samples can be used to distinguish dietary patterns and monitor shifts in metabolism. But for these variations to have meaning, the isotopic signature of the diet must be known. We sought to determine if knowledge of the 13C isotopic abund...

  12. Protonation of carbon single-walled nanotubes studied using 13C and 1H-13C cross polarization nuclear magnetic resonance and Raman spectroscopies.

    PubMed

    Engtrakul, Chaiwat; Davis, Mark F; Gennett, Thomas; Dillon, Anne C; Jones, Kim M; Heben, Michael J

    2005-12-14

    The reversible protonation of carbon single-walled nanotubes (SWNTs) in sulfuric acid and Nafion was investigated using solid-state nuclear magnetic resonance (NMR) and Raman spectroscopies. Magic-angle spinning (MAS) was used to obtain high-resolution 13C and 1H-13C cross polarization (CP) NMR spectra. The 13C NMR chemical shifts are reported for bulk SWNTs, H2SO4-treated SWNTs, SWNT-Nafion polymer composites, SWNT-AQ55 polymer composites, and SWNTs in contact with water. Protonation occurs without irreversible oxidation of the nanotube substrate via a charge-transfer process. This is the first report of a chemically induced change in a SWNT 13C resonance brought about by a reversible interaction with an acidic proton, providing additional evidence that carbon nanotubes behave as weak bases. Cross polarization was found to be a powerful technique for providing an additional contrast mechanism for studying nanotubes in contact with other chemical species. The CP studies confirmed polarization transfer from nearby protons to nanotube carbon atoms. The CP technique was also applied to investigate water adsorbed on carbon nanotube surfaces. Finally, the degree of bundling of the SWNTs in Nafion films was probed with the 1H-13C CP-MAS technique. PMID:16332107

  13. The cluster and single-particle states in 13C (α,α)13C reactions

    NASA Astrophysics Data System (ADS)

    Mynbayev, N. A.; Nurmukhanbetova, A. K.; Goldberg, V. Z.; Rogachev, G. V.; Golovkov, M. S.; Koloberdin, M.; Ivanov, I.; Nauruzbayev, D. K.; Berdibek, Sh S.; Rakhymzhanov, A. M.; Tribble, R. E.

    2016-06-01

    The excitation functions of elastic scattering of 13C on alpha particle have been measured using the thick-target inverse kinematic method at the heavy ion DC-60 cyclotron. The helium gas was used as a target and also as a degrader to stop the beam. New data (including 180°degree) of the resonances close to the threshold in 17O have been obtained.

  14. CARBON-13 NUCLEAR MAGNETIC RESONANCE. 13C CHEMICAL SHIFTS AND 13C-199HG COUPLING CONSTANTS FOR SOME ORGANOMERCURY COMPOUNDS

    EPA Science Inventory

    The (13)C shieldings and (13)C-(199)Hg coupling constants of fourteen phenyl- and seven alkyl- and alkenyl-mercury compounds have been obtained. Substituent effects on the (13)C shieldings are similar to those in nonmercurated phenyl compounds, with a similar relationship between...

  15. Clinical NOE 13C MRS for neuropsychiatric disorders of the frontal lobe

    NASA Astrophysics Data System (ADS)

    Sailasuta, Napapon; Robertson, Larry W.; Harris, Kent C.; Gropman, Andrea L.; Allen, Peter S.; Ross, Brian D.

    2008-12-01

    In this communication, a scheme is described whereby in vivo 13C MRS can safely be performed in the frontal lobe, a human brain region hitherto precluded on grounds of SAR, but important in being the seat of impaired cognitive function in many neuropsychiatric and developmental disorders. By combining two well known features of 13C NMR—the use of low power NOE and the focus on 13C carbon atoms which are only minimally coupled to protons, we are able to overcome the obstacle of SAR and develop means of monitoring the 13C fluxes of critically important metabolic pathways in frontal brain structures of normal volunteers and patients. Using a combination of low-power WALTZ decoupling, variants of random noise for nuclear overhauser effect enhancement it was possible to reduce power deposition to 20% of the advised maximum specific absorption rate (SAR). In model solutions 13C signal enhancement achieved with this scheme were comparable to that obtained with WALTZ-4. In human brain, the low power procedure effectively determined glutamine, glutamate and bicarbonate in the posterior parietal brain after [1- 13C] glucose infusion. The same 13C enriched metabolites were defined in frontal brain of human volunteers after administration of [1- 13C] acetate, a recognized probe of glial metabolism. Time courses of incorporation of 13C into cerebral glutamate, glutamine and bicarbonate were constructed. The results suggest efficacy for measurement of in vivo cerebral metabolic rates of the glutamate-glutamine and tricarboxylic acid cycles in 20 min MR scans in previously inaccessible brain regions in humans at 1.5T. We predict these will be clinically useful biomarkers in many human neuropsychiatric and genetic conditions.

  16. 13C breath tests in infections and beyond.

    PubMed

    Kurpad, Anura V; Ajami, Alfred; Young, Vernon R

    2002-09-01

    Stable isotope labeled compounds are widely used as diagnostic probes in medicine. These diagnostic stable isotope probes are now being expanded in their scope, to provide precise indications of the presence or absence of etiologically significant change in metabolism due to a specific disease. This concept exploits a labeled tracer probe that is a specifically designed substrate of a "gateway" enzyme in a discrete metabolic pathway, whose turnover can be measured by monitoring unidirectional precursor product mass flow. An example of such a probe is the 13C-urea breath test, where labeled urea is given to patients with H. pylori infection. Another example of this kind of probe is used to study the tripeptide glutathione (glu-cys-gly, GSH), which is the most abundant cellular thiol, and protects cells from the toxic effects of reactive oxygen species. Within the gamma glutamyl cycle, 5-oxoproline (L-pyroglutamic acid) is a metabolite generated during GSH catabolism, and is metabolized to glutamic acid by 5-oxoprolinase. This enzyme can also utilize the substrate L-2-oxothiazolidone-4-carboxylate (OTC), to generate intracellular cysteine, which is beneficial to the cell. Thus, labeled (13C) OTC would, under enzymatic attack yield cysteine and 13CO2, and can thus track the state and capacity of glutathione metabolism. Similarly, stable isotope labeled probes can be used to track the activity of the rate of homocysteine clearance, lymphocyte CD26, and liver CYP (cytochrome P450) enzyme activity. In the future, these applications should be able to titrate, in vivo, the characteristics of various specific enzyme systems in the body and their response to stress or infection as well as to treatment regimes. PMID:12362798

  17. A Peptide-Based Method for 13C Metabolic Flux Analysis in Microbial Communities

    PubMed Central

    Ghosh, Amit; Nilmeier, Jerome; Weaver, Daniel; Adams, Paul D.; Keasling, Jay D.; Mukhopadhyay, Aindrila; Petzold, Christopher J.; Martín, Héctor García

    2014-01-01

    The study of intracellular metabolic fluxes and inter-species metabolite exchange for microbial communities is of crucial importance to understand and predict their behaviour. The most authoritative method of measuring intracellular fluxes, 13C Metabolic Flux Analysis (13C MFA), uses the labeling pattern obtained from metabolites (typically amino acids) during 13C labeling experiments to derive intracellular fluxes. However, these metabolite labeling patterns cannot easily be obtained for each of the members of the community. Here we propose a new type of 13C MFA that infers fluxes based on peptide labeling, instead of amino acid labeling. The advantage of this method resides in the fact that the peptide sequence can be used to identify the microbial species it originates from and, simultaneously, the peptide labeling can be used to infer intracellular metabolic fluxes. Peptide identity and labeling patterns can be obtained in a high-throughput manner from modern proteomics techniques. We show that, using this method, it is theoretically possible to recover intracellular metabolic fluxes in the same way as through the standard amino acid based 13C MFA, and quantify the amount of information lost as a consequence of using peptides instead of amino acids. We show that by using a relatively small number of peptides we can counter this information loss. We computationally tested this method with a well-characterized simple microbial community consisting of two species. PMID:25188426

  18. Compartmentalized Cerebral Metabolism of [1,6-13C]Glucose Determined by in vivo 13C NMR Spectroscopy at 14.1 T

    PubMed Central

    Duarte, João M. N.; Lanz, Bernard; Gruetter, Rolf

    2011-01-01

    Cerebral metabolism is compartmentalized between neurons and glia. Although glial glycolysis is thought to largely sustain the energetic requirements of neurotransmission while oxidative metabolism takes place mainly in neurons, this hypothesis is matter of debate. The compartmentalization of cerebral metabolic fluxes can be determined by 13C nuclear magnetic resonance (NMR) spectroscopy upon infusion of 13C-enriched compounds, especially glucose. Rats under light α-chloralose anesthesia were infused with [1,6-13C]glucose and 13C enrichment in the brain metabolites was measured by 13C NMR spectroscopy with high sensitivity and spectral resolution at 14.1 T. This allowed determining 13C enrichment curves of amino acid carbons with high reproducibility and to reliably estimate cerebral metabolic fluxes (mean error of 8%). We further found that TCA cycle intermediates are not required for flux determination in mathematical models of brain metabolism. Neuronal tricarboxylic acid cycle rate (VTCA) and neurotransmission rate (VNT) were 0.45 ± 0.01 and 0.11 ± 0.01 μmol/g/min, respectively. Glial VTCA was found to be 38 ± 3% of total cerebral oxidative metabolism, accounting for more than half of neuronal oxidative metabolism. Furthermore, glial anaplerotic pyruvate carboxylation rate (VPC) was 0.069 ± 0.004 μmol/g/min, i.e., 25 ± 1% of the glial TCA cycle rate. These results support a role of glial cells as active partners of neurons during synaptic transmission beyond glycolytic metabolism. PMID:21713114

  19. Long-acting Neuraminidase Inhibitor Laninamivir Octanoate as Post-exposure Prophylaxis for Influenza

    PubMed Central

    Kashiwagi, Seizaburo; Watanabe, Akira; Ikematsu, Hideyuki; Uemori, Mitsutoshi; Awamura, Shinichiro

    2016-01-01

    Background. A single administration of laninamivir octanoate, a long-acting neuraminidase inhibitor, has been proven to be effective in the treatment of influenza but not for post-exposure prophylaxis. Methods. We conducted a double-blind, multicenter, randomized, placebo-controlled study to determine if a single administration of laninamivir octanoate 40 mg was superior to placebo for post-exposure prophylaxis. Eligible participants who had cohabited with an influenza patient within 48 hours of symptom onset were randomly assigned (1:1:1) to 1 of 3 groups: 40 mg of laninamivir octanoate single administration (LO-40SD), 20 mg of laninamivir octanoate once daily for 2 days (LO-20TD), or placebo. The primary efficacy endpoint was the proportion of participants who developed clinical influenza (defined as influenza virus positive, an axillary temperature >37.5°C, and at least 2 symptoms) over a 10-day period. Results. A total of 803 participants were enrolled, with 801 included in the primary analysis. The proportions of participants with clinical influenza were 4.5% (12/267), 4.5% (13/269), and 12.1% (32/265) in the LO-40SD, LO-20TD, and placebo groups, respectively. A single administration of laninamivir octanoate 40 mg significantly reduced the development of influenza compared with placebo (P = .001). The relative risk reductions compared with the placebo group were 62.8% and 63.1% for the LO-40SD and LO-20TD groups, respectively. The incidence of adverse events in the LO-40SD group was similar to that of the LO-20TD and placebo groups. Conclusions. A single administration of laninamivir octanoate was effective and well tolerated as post-exposure prophylaxis to prevent the development of influenza. Clinical Trials Registration. JapicCTI-142679. PMID:27118785

  20. Two new organic reference materials for δ13C and δ15N measurements and a new value for the δ13C of NBS 22 oil

    USGS Publications Warehouse

    Qi, Haiping; Coplen, Tyler B.; Geilmann, Heike; Brand, Willi A.; Bohlke, John Karl

    2003-01-01

    Analytical grade L-glutamic acid is chemically stable and has a C/N mole ratio of 5, which is close to that of many of natural biological materials, such as blood and animal tissue. Two L-glutamic acid reference materials with substantially different 13C and 15N abundances have been prepared for use as organic reference materials for C and N isotopic measurements. USGS40 is analytical grade L-glutamic acid and has a δ13C value of −26.24‰ relative to VPDB and a δ15N value of −4.52‰ relative to N2 in air. USGS41 was prepared by dissolving analytical grade L-glutamic acid with L-glutamic acid enriched in 13C and 15N. USGS41 has a δ13C value of +37.76‰ and a δ15N value of +47.57‰. The δ13C and δ15N values of both materials were measured against the international reference materials NBS 19 calcium carbonate (δ13C = +1.95‰), L-SVEC lithium carbonate (δ13C = −46.48‰), IAEA-N-1 ammonium sulfate (δ15N = 0.43‰), and USGS32 potassium nitrate (δ15N = 180‰) by on-line combustion continuous-flow and off-line dual-inlet isotope-ratio mass spectrometry. Both USGS40 and USGS41 are isotopically homogeneous; reproducibility of δ13C is better than 0.13‰, and that of δ15N is better than 0.13‰ in 100-μg amounts. These two isotopic reference materials can be used for (i) calibrating local laboratory reference materials, and (ii) quantifying drift with time, mass-dependent fractionations, and isotope-ratio-scale contraction in the isotopic analysis of various biological materials. Isotopic results presented in this paper yield a δ13C value for NBS 22 oil of −29.91‰, in contrast to the commonly accepted value of −29.78‰ for which off-line blank corrections probably have not been quantified satisfactorily.

  1. Synthesis Of [2h, 13c]M [2h2m 13c], And [2h3,, 13c] Methyl Aryl Sulfones And Sulfoxides

    DOEpatents

    Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.; Schmidt, Jurgen G.

    2004-07-20

    The present invention is directed to labeled compounds, [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2, .sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfones and [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2, .sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfoxides, wherein the .sup.13 C methyl group attached to the sulfur of the sulfone or sulfoxide includes exactly one, two or three deuterium atoms and the aryl group is selected from the group consisting of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently, hydrogen, a C.sub.1 -C.sub.4 lower alkyl, a halogen, an amino group from the group consisting of NH.sub.2, NHR and NRR' where R and R' are each a C.sub.1 -C.sub.4 lower alkyl, a phenyl, or an alkoxy group. The present invention is also directed to processes of preparing methyl aryl sulfones and methyl aryl sulfoxides.

  2. (13)C NMR-based metabolomics for the classification of green coffee beans according to variety and origin.

    PubMed

    Wei, Feifei; Furihata, Kazuo; Koda, Masanori; Hu, Fangyu; Kato, Rieko; Miyakawa, Takuya; Tanokura, Masaru

    2012-10-10

    (13)C NMR-based metabolomics was demonstrated as a useful tool for distinguishing the species and origins of green coffee bean samples of arabica and robusta from six different geographic regions. By the application of information on (13)C signal assignment, significantly different levels of 14 metabolites of green coffee beans were identified in the classifications, including sucrose, caffeine, chlorogenic acids, choline, amino acids, organic acids, and trigonelline, as captured by multivariate analytical models. These studies demonstrate that the species and geographical origin can be quickly discriminated by evaluating the major metabolites of green coffee beans quantitatively using (13)C NMR-based metabolite profiling. PMID:22989016

  3. Investigating brain metabolism at high fields using localized 13C NMR spectroscopy without 1H decoupling.

    PubMed

    Deelchand, Dinesh Kumar; Uğurbil, Kâmil; Henry, Pierre-Gilles

    2006-02-01

    Most in vivo 13C NMR spectroscopy studies in the brain have been performed using 1H decoupling during acquisition. Decoupling imposes significant constraints on the experimental setup (particularly for human studies at high magnetic field) in order to stay within safety limits for power deposition. We show here that incorporation of the 13C label from 13C-labeled glucose into brain amino acids can be monitored accurately using localized 13C NMR spectroscopy without the application of 1H decoupling. Using LCModel quantification with prior knowledge of one-bond and multiple-bond J(CH) coupling constants, the uncertainty on metabolites concentrations was only 35% to 91% higher (depending on the carbon resonance of interest) in undecoupled spectra compared to decoupled spectra in the rat brain at 9.4 Tesla. Although less sensitive, 13C NMR without decoupling dramatically reduces experimental constraints on coil setup and pulse sequence design required to keep power deposition within safety guidelines. This opens the prospect of safely measuring 13C NMR spectra in humans at varied brain locations (not only the occipital lobe) and at very high magnetic fields above 4 Tesla. PMID:16345037

  4. 13C-labelled microdialysis studies of cerebral metabolism in TBI patients☆

    PubMed Central

    Carpenter, Keri L.H.; Jalloh, Ibrahim; Gallagher, Clare N.; Grice, Peter; Howe, Duncan J.; Mason, Andrew; Timofeev, Ivan; Helmy, Adel; Murphy, Michael P.; Menon, David K.; Kirkpatrick, Peter J.; Carpenter, T. Adrian; Sutherland, Garnette R.; Pickard, John D.; Hutchinson, Peter J.

    2014-01-01

    Human brain chemistry is incompletely understood and better methodologies are needed. Traumatic brain injury (TBI) causes metabolic perturbations, one result of which includes increased brain lactate levels. Attention has largely focussed on glycolysis, whereby glucose is converted to pyruvate and lactate, and is proposed to act as an energy source by feeding into neurons’ tricarboxylic acid (TCA) cycle, generating ATP. Also reportedly upregulated by TBI is the pentose phosphate pathway (PPP) that does not generate ATP but produces various molecules that are putatively neuroprotective, antioxidant and reparative, in addition to lactate among the end products. We have developed a novel combination of 13C-labelled cerebral microdialysis both to deliver 13C-labelled substrates into brains of TBI patients and recover the 13C-labelled metabolites, with high-resolution 13C NMR analysis of the microdialysates. This methodology has enabled us to achieve the first direct demonstration in humans that the brain can utilise lactate via the TCA cycle. We are currently using this methodology to make the first direct comparison of glycolysis and the PPP in human brain. In this article, we consider the application of 13C-labelled cerebral microdialysis for studying brain energy metabolism in patients. We set this methodology within the context of metabolic pathways in the brain, and 13C research modalities addressing them. PMID:24361470

  5. [2,4-13C2]-β-Hydroxybutyrate Metabolism in Human Brain

    PubMed Central

    Pan, Jullie W.; de Graaf, Robin A.; Petersen, Kitt F.; Shulman, Gerald I.; Hetherington, Hoby P.; Rothman, Douglas L.

    2010-01-01

    Summary Infusions of [2,4-13C2]-β-hydroxybutyrate and 1H–13C polarization transfer spectroscopy were used in normal human subjects to detect the entry and metabolism of β-hydroxybutyrate in the brain. During the 2-hour infusion study, 13C label was detectable in the β-hydroxybutyrate resonance positions and in the amino acid pools of glutamate, glutamine, and aspartate. With a plasma concentration of 2.25 ± 0.24 mmol/L (four volunteers), the apparent tissue β-hydroxybutyrate concentration reached 0.18 ± 0.06 mmol/L during the last 20 minutes of the study. The relative fractional enrichment of 13C-4-glutamate labeling was 6.78 ± 1.71%, whereas 13C-4-glutamine was 5.68 ± 1.84%. Steady-state modeling of the 13C label distribution in glutamate and glutamine suggests that, under these conditions, the consumption of the β-hydroxybutyrate is predominantly neuronal, used at a rate of 0.032 ± 0.009 mmol · kg−1 · min−1, and accounts for 6.4 ± 1.6% of total acetyl coenzyme A oxidation. These results are consistent with minimal accumulation of cerebral ketones with rapid utilization, implying blood–brain barrier control of ketone oxidation in the nonfasted adult human brain. PMID:12142574

  6. [2,4-13 C2 ]-beta-Hydroxybutyrate metabolism in human brain.

    PubMed

    Pan, Jullie W; de Graaf, Robin A; Petersen, Kitt F; Shulman, Gerald I; Hetherington, Hoby P; Rothman, Douglas L

    2002-07-01

    Infusions of [2,4-13C2]-beta-hydroxybutyrate and 1H-13C polarization transfer spectroscopy were used in normal human subjects to detect the entry and metabolism of beta-hydroxybutyrate in the brain. During the 2-hour infusion study, 13C label was detectable in the beta-hydroxybutyrate resonance positions and in the amino acid pools of glutamate, glutamine, and aspartate. With a plasma concentration of 2.25 +/- 0.24 mmol/L (four volunteers), the apparent tissue beta-hydroxybutyrate concentration reached 0.18 +/- 0.06 mmol/L during the last 20 minutes of the study. The relative fractional enrichment of 13C-4-glutamate labeling was 6.78 +/- 1.71%, whereas 13C-4-glutamine was 5.68 +/- 1.84%. Steady-state modeling of the 13C label distribution in glutamate and glutamine suggests that, under these conditions, the consumption of the beta-hydroxybutyrate is predominantly neuronal, used at a rate of 0.032 +/- 0.009 mmol. kg-1. min-1, and accounts for 6.4 +/- 1.6% of total acetyl coenzyme A oxidation. These results are consistent with minimal accumulation of cerebral ketones with rapid utilization, implying blood-brain barrier control of ketone oxidation in the nonfasted adult human brain. PMID:12142574

  7. The effect of chemical processing on the δ 13C value of plant tissue

    NASA Astrophysics Data System (ADS)

    Van de Water, Peter K.

    2002-04-01

    The effect of standard processing techniques on the δ 13C value of plant tissue was tested using species representing the three photosynthetic pathways, including angiosperms and gymnosperms within the C 3 taxonomic division. The species include Cowania mexicana (C 3 angiosperm), Juniperus osteosperma (C 3 gymnosperm), Opuntia spp. (crassulacean acid metabolism [CAM] angiosperm), and Atriplex canescens (C 4 angiosperm). Each species is represented by 5 plants collected at two different sites, for a total of 10 samples. The samples were processed to whole plant tissue, holocellulose, α-cellulose, and nitrocellulose. An additional process was added with the discovery of residual Ca-oxalate crystals in holocellulose samples. Both C 3 species show δ 13C values becoming 13C enriched with increased processing. The CAM representative shows the opposite trend, with 13C depletion during the progression of treatments. The greatest range of values and most inconsistent trends occur in the C 4 representative. Removal of the Ca-oxalate fraction resulted in different mean weight percentages and δ 13C values among the species. Calculated δ 13C values of the Ca-oxalate crystals show depletion from the tissue values in the two C 3 species and enrichment in the C 4 and CAM representatives. The C. mexicana samples show the greatest change between the tissue and Ca-oxalates (7.3‰) but the least mean weight percentage (11%), whereas A. canescens shows the greatest overall change, with a -2.8‰ isotopic shift and over 48% mean weight percentage. Variability within the samples undergoing each treatment remained relatively unchanged even with increased cellulose purity. This paper provides estimates of isotopic offsets necessary to correct from one treatment to another. Significant differences in δ 13C among different treatments confirm the need to state the tissue fraction analyzed when reporting δ 13C results.

  8. Regioselective Syntheses of [13C]4-Labelled Sodium 1-Carboxy-2-(2-ethylhexyloxycarbonyl)ethanesulfonate and Sodium 2-Carboxy-1-(2-ethylhexyloxycarbonyl)ethanesulfonate from [13C]4-Maleic Anhydride

    PubMed Central

    Barsamian, Adam L.; Perkins, Matt J.; Field, Jennifer A.; Blakemore, Paul R.

    2014-01-01

    The entitled monohydrolysis products, also known as α- and β-ethylhexyl sulfosuccinate ('EHSS'), of the surfactant diisooctyl sulfosuccinate ('DOSS') were synthesized in stable isotope labelled form from [13C]4-maleic anhydride. Sodium [13C]4-1-carboxy-2-(2-ethylhexyloxycarbonyl)ethanesulfonate (α-EHSS) was prepared by the method of Larpent by reaction of 2-ethylhexan-1-ol with [13C]4-maleic anhydride followed by regioselective conjugate addition of sodium bisulfite to the resulting monoester (38% overall yield). The regiochemical outcome of bisulfite addition was confirmed by a combination of 13C/13C (INADEQUATE) and 1H/13C (HMBC) NMR spectral correlation experiments. Sodium [13C]4-2-carboxy-1-(2-ethylhexyloxycarbonyl)ethanesulfonate (β-EHSS) was prepared in four steps by reaction of 4-methoxybenzyl alcohol (PMBOH) with [13C]4-maleic anhydride, regioselective sodium bisulfite addition, DCC mediated esterification with 2-ethylhexan-1-ol, and PMB ester deprotection with trifluoroacetic acid (13% overall yield). The regiochemical outcome of the second synthesis was confirmed by a combination of 1JCC scalar coupling constant analysis and 1H/13C (HMBC) NMR spectral correlation. The materials prepared are required as internal standards for the LC-MS/MS trace analysis of the degradation products of DOSS, the anionic surfactant found in Corexit, the oil dispersant used during emergency response efforts connected to the Deepwater Horizon oil spill of April 2010. PMID:24700711

  9. Non-stationary (13)C-metabolic flux ratio analysis.

    PubMed

    Hörl, Manuel; Schnidder, Julian; Sauer, Uwe; Zamboni, Nicola

    2013-12-01

    (13)C-metabolic flux analysis ((13)C-MFA) has become a key method for metabolic engineering and systems biology. In the most common methodology, fluxes are calculated by global isotopomer balancing and iterative fitting to stationary (13)C-labeling data. This approach requires a closed carbon balance, long-lasting metabolic steady state, and the detection of (13)C-patterns in a large number of metabolites. These restrictions mostly reduced the application of (13)C-MFA to the central carbon metabolism of well-studied model organisms grown in minimal media with a single carbon source. Here we introduce non-stationary (13)C-metabolic flux ratio analysis as a novel method for (13)C-MFA to allow estimating local, relative fluxes from ultra-short (13)C-labeling experiments and without the need for global isotopomer balancing. The approach relies on the acquisition of non-stationary (13)C-labeling data exclusively for metabolites in the proximity of a node of converging fluxes and a local parameter estimation with a system of ordinary differential equations. We developed a generalized workflow that takes into account reaction types and the availability of mass spectrometric data on molecular ions or fragments for data processing, modeling, parameter and error estimation. We demonstrated the approach by analyzing three key nodes of converging fluxes in central metabolism of Bacillus subtilis. We obtained flux estimates that are in agreement with published results obtained from steady state experiments, but reduced the duration of the necessary (13)C-labeling experiment to less than a minute. These results show that our strategy enables to formally estimate relative pathway fluxes on extremely short time scale, neglecting cellular carbon balancing. Hence this approach paves the road to targeted (13)C-MFA in dynamic systems with multiple carbon sources and towards rich media. PMID:23860906

  10. Functional groups identified by solid state 13C NMR spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Animal manure is generally high in organic matter intensity so it is well suitable for 13C nuclear magnetic resonance (NMR) analysis. Solid-state 13C NMR techniques used in characterizing organic matter and its components include, but are not limited to, cross-polarization /magic angle spinning (CP...

  11. Identification of natural metabolites in mixture: a pattern recognition strategy based on (13)C NMR.

    PubMed

    Hubert, Jane; Nuzillard, Jean-Marc; Purson, Sylvain; Hamzaoui, Mahmoud; Borie, Nicolas; Reynaud, Romain; Renault, Jean-Hugues

    2014-03-18

    Because of their highly complex metabolite profile, the chemical characterization of bioactive natural extracts usually requires time-consuming multistep purification procedures to achieve the structural elucidation of pure individual metabolites. The aim of the present work was to develop a dereplication strategy for the identification of natural metabolites directly within mixtures. Exploiting the polarity range of metabolites, the principle was to rapidly fractionate a multigram quantity of a crude extract by centrifugal partition extraction (CPE). The obtained fractions of simplified chemical composition were subsequently analyzed by (13)C NMR. After automatic collection and alignment of (13)C signals across spectra, hierarchical clustering analysis (HCA) was performed for pattern recognition. As a result, strong correlations between (13)C signals of a single structure within the mixtures of the fraction series were visualized as chemical shift clusters. Each cluster was finally assigned to a molecular structure with the help of a locally built (13)C NMR chemical shift database. The proof of principle of this strategy was achieved on a simple model mixture of commercially available plant secondary metabolites and then applied to a bark extract of the African tree Anogeissus leiocarpus Guill. & Perr. (Combretaceae). Starting from 5 g of this genuine extract, the fraction series was generated by CPE in only 95 min. (13)C NMR analyses of all fractions followed by pattern recognition of (13)C chemical shifts resulted in the unambiguous identification of seven major compounds, namely, sericoside, trachelosperogenin E, ellagic acid, an epimer mixture of (+)-gallocatechin and (-)-epigallocatechin, 3,3'-di-O-methylellagic acid 4'-O-xylopyranoside, and 3,4,3'-tri-O-methylflavellagic acid 4'-O-glucopyranoside. PMID:24555703

  12. Determination of [{sup 13}C]pyrene sequestration in sediment microcosms using flash pyrolysis--GC--MS and {sup 13}C NMR

    SciTech Connect

    Guthrie, E.A.; Bortiatynski, J.M.; Hardy, K.S.; Kovach, E.M.; Van Heemst, J.D.H.; Hatcher, P.G.; Richman, J.E.

    1999-01-01

    In this study, the use of a {sup 13}C-labeled pollutant probe, [{sup 13}C]pyrene, and the application of flash pyrolysis--GC--MS and CPMAS {sup 13}C NMR provided analytical capabilities to study pyrene interactions with soluble and insoluble compartments of sedimentary organic matter (S{sub D}OM) during whole sediments incubations in aerated microcosms. Surface sediments were collected from a site of previous hydrocarbon contamination in New Orleans, LA. Over a period of 60 days, humic acid and humin fractions of S{sub D}OM accumulated increasing amounts of pyrene that were resistant to exhaustive extraction with organic solvents. The sequestered pyrene was evident in CPMAS {sup 13}C NMR spectra of humin fractions. The amount of sequestered pyrene in humic materials was quantified by flash pyrolysis--GC--MS, a technique that destroys the three-dimensional structure of macromolecular S{sub D}OM. Noncovalent binding of pyrene to humic materials in S{sub D}OM was greater in sediments incubated with biological activity than biocide-treated sediments. The combined analytical approaches demonstrate that the sequestered pyrene, or bound residue, is noncovalently associated with S{sub D}OM and has not undergone structural alteration. Implications of these data are discussed in reference to S{sub D}OM diagenesis and long-term availability of bound pollutant residues in sediments.

  13. Whole-core analysis by sup 13 C NMR

    SciTech Connect

    Vinegar, H.J.; Tutunjian, P.N. ); Edelstein, W.A.; Roemer, P.B. )

    1991-06-01

    This paper reports on a whole-core nuclear magnetic resonance (NMR) system that was used to obtain natural abundance {sup 13}C spectra. The system enables rapid, nondestructive measurements of bulk volume of movable oil, aliphatic/aromatic ratio, oil viscosity, and organic vs. carbonate carbon. {sup 13}C NMR can be used in cores where the {sup 1}H NMR spectrum is too broad to resolve oil and water resonances separately. A 5 1/4-in. {sup 13}C/{sup 1}H NMR coil was installed on a General Electric (GE) CSI-2T NMR imager/spectrometer. With a 4-in.-OD whole core, good {sup 13}C signal/noise ratio (SNR) is obtained within minutes, while {sup 1}H spectra are obtained in seconds. NMR measurements have been made of the {sup 13}C and {sup 1}H density of crude oils with a wide range of API gravities. For light- and medium-gravity oils, the {sup 13}C and {sup 1}H signal per unit volume is constant within about 3.5%. For heavy crudes, the {sup 13}C and {sup 1}H density measured by NMR is reduced by the shortening of spin-spin relaxation time. {sup 13}C and {sup 1}H NMR spin-lattice relaxation times were measured on a suite of Cannon viscosity standards, crude oils (4 to 60{degrees} API), and alkanes (C{sub 5} through C{sub 16}) with viscosities at 77{degrees}F ranging from 0.5 cp to 2.5 {times} 10{sup 7} cp. The {sup 13}C and {sup 1}H relaxation times show a similar correlation with viscosity from which oil viscosity can be estimated accurately for viscosities up to 100 cp. The {sup 13}C surface relaxation rate for oils on water-wet rocks is very low. Nonproton decoupled {sup 13}C NMR is shown to be insensitive to kerogen; thus, {sup 13}C NMR measures only the movable hydrocarbon content of the cores. In carbonates, the {sup 13}C spectrum also contains a carbonate powder pattern useful in quantifying inorganic carbon and distinguishing organic from carbonate carbon.

  14. Accurate quantitative 13C NMR spectroscopy: repeatability over time of site-specific 13C isotope ratio determination.

    PubMed

    Caytan, Elsa; Botosoa, Eliot P; Silvestre, Virginie; Robins, Richard J; Akoka, Serge; Remaud, Gérald S

    2007-11-01

    The stability over time (repeatability) for the determination of site-specific 13C/12C ratios at natural abundance by quantitative 13C NMR spectroscopy has been tested on three probes: enriched bilabeled [1,2-13C2]ethanol; ethanol at natural abundance; and vanillin at natural abundance. It is shown in all three cases that the standard deviation for a series of measurements taken every 2-3 months over periods between 9 and 13 months is equal to or smaller than the standard deviation calculated from 5-10 replicate measurements made on a single sample. The precision which can be achieved using the present analytical 13C NMR protocol is higher than the prerequisite value of 1-2 per thousand for the determination of site-specific 13C/12C ratios at natural abundance (13C-SNIF-NMR). Hence, this technique permits the discrimination of very small variations in 13C/12C ratios between carbon positions, as found in biogenic natural products. This observed stability over time in 13C NMR spectroscopy indicates that further improvements in precision will depend primarily on improved signal-to-noise ratio. PMID:17900175

  15. State-of-the-Art Direct 13C and Indirect 1H-[13C] NMR Spectroscopy In Vivo

    PubMed Central

    de Graaf, Robin A.; Rothman, Douglas L.; Behar, Kevin L.

    2013-01-01

    Carbon-13 NMR spectroscopy in combination with 13C-labeled substrate infusion is a powerful technique to measure a large number of metabolic fluxes non-invasively in vivo. It has been used to quantify glycogen synthesis rates, establish quantitative relationships between energy metabolism and neurotransmission and evaluate the importance of different substrates. All measurements can, in principle, be performed through direct 13C NMR detection or via indirect 1H-[13C] NMR detection of the protons attached to 13C nuclei. The choice for detection scheme and pulse sequence depends on the magnetic field strength, whereas substrate selection depends on the metabolic pathways that are studied. 13C NMR spectroscopy remains a challenging technique that requires several non-standard hardware modifications, infusion of 13C-labeled substrates and sophisticated processing and metabolic modeling. Here the various aspects of direct 13C and indirect 1H-[13C] NMR are reviewed with the aim of providing a practical guide. PMID:21919099

  16. Theoretical estimation of 13C-D clumped isotope effects in methyl of several organic compound

    NASA Astrophysics Data System (ADS)

    LIU, Q.; Yin, X.; Liu, Y.

    2015-12-01

    Recent developments in mass spectrometry and tunable infrared laser direct absorption spectroscopy make it possible to measure 13C-D clumped isotope effects of methane. These techniques can be further applied to determine 13C-D clumped isotope effects of methyl fragments, therefore need accurate equilirbium Δi values to calibrate experimental measurements. In this study, we calculate temperature depandences of 13C-D clumped isotope signatures in methyl of several organic compounds including ethane, propane, acetic acid, etc. Our calculation are performed at CCSD/6-311+G(3df,3pd) by using Gaussian 03 program with no scale treament. Our results show that the Δi values of 13C-D clumping in methyl fragments of different organic compounds yield similar signals (~5.5‰ at 25˚C, slightly lower than Δi value of 13C-D clumping in methane). For testing the calculated accuracy, theoretical treaments beyond the harmonic level by including several higher-order corrections to the Bigeleisen-Mayer equation are used. Contributions from higher-order corrections (e.g., AnZPE, AnEXC, VrZPE, VrEXC, QmCorr and CenDist) are estimated to repire the ignorings of the Bigeleisen-Mayer equation (the anharmonic effects of vibration, vibration-rotation coupling, quantum mechanics and centrifugal distortion for rotation, etc.) for the calculation of partition function ratios. The results show that the higher-order corrections contribute ~0.05‰ at 25˚C, which is similar to the contribution for calculating 13C-D clumped isotope signature of methane. By comparing our calculated frequencies to the measured ones, the uncertainty of our calculation of Δi values 13C-D clumping in methyl fragments is considered to be within ~0.05‰ at room temperature.

  17. 13C-phenylalanine breath test detects altered phenylalanine kinetics in schizophrenia patients.

    PubMed

    Teraishi, T; Ozeki, Y; Hori, H; Sasayama, D; Chiba, S; Yamamoto, N; Tanaka, H; Iijima, Y; Matsuo, J; Kawamoto, Y; Kinoshita, Y; Hattori, K; Ota, M; Kajiwara, M; Terada, S; Higuchi, T; Kunugi, H

    2012-01-01

    Phenylalanine is an essential amino acid required for the synthesis of catecholamines including dopamine. Altered levels of phenylalanine and its metabolites in blood and cerebrospinal fluid have been reported in schizophrenia patients. This study attempted to examine for the first time whether phenylalanine kinetics is altered in schizophrenia using L-[1-(13)C]phenylalanine breath test ((13)C-PBT). The subjects were 20 chronically medicated schizophrenia patients (DSM-IV) and the same number of age- and sex-matched controls. (13)C-phenylalanine (99 atom% (13)C; 100 mg) was administered orally and the breath (13)CO(2) /(12)CO(2) ratio was monitored for 120 min. The possible effect of antipsychotic medication (risperidone (RPD) or haloperidol (HPD) treatment for 21 days) on (13)C-PBT was examined in rats. Body weight (BW), age and diagnostic status were significant predictors of the area under the curve of the time course of Δ(13)CO(2) (‰) and the cumulative recovery rate (CRR) at 120 min. A repeated measures analysis of covariance controlled for age and BW revealed that the patterns of CRR change over time differed between the patients and controls and that Δ(13)CO(2) was lower in the patients than in the controls at all sampling time points during the 120 min test, with an overall significant difference between the two groups. Chronic administration of RPD or HPD had no significant effect on (13)C-PBT indices in rats. Our results suggest that (13)C-PBT is a novel laboratory test that can detect altered phenylalanine kinetics in chronic schizophrenia patients. Animal experiments suggest that the observed changes are unlikely to be attributable to antipsychotic medication. PMID:22832963

  18. Sensitivity-enhanced IPAP experiments for measuring one-bond 13C '- 13C α and 13C α- 1H α residual dipolar couplings in proteins

    NASA Astrophysics Data System (ADS)

    Ding, Keyang; Gronenborn, Angela M.

    2004-04-01

    Sensitivity-enhanced 2D IPAP experiments using the accordion principle for measuring one-bond 13C '- 13C α and 1H α- 13C α dipolar couplings in proteins are presented. The resolution of the resulting spectra is identical to that of the decoupled HSQC spectra and the sensitivity of the corresponding 1D acquisitions are only slightly lower than those obtained with 3D HNCO and 3D HN(COCA)HA pulse sequences due to an additional delay 2 Δ. For cases of limited resolution in the 2D 15N- 1H N HSQC spectrum the current pulse sequences can easily be modified into 3D versions by introducing a poorly digitized third dimension, if so desired. The experiments described here are a valuable addition to the suites available for determination of residual dipolar couplings in biological systems.

  19. Methylation patterns of aquatic humic substances determined by 13C NMR spectroscopy

    USGS Publications Warehouse

    Thorn, K.A.; Steelink, C.; Wershaw, R. L.

    1987-01-01

    13C NMR spectroscopy is used to examine the hydroxyl group functionality of a series of humic and fulvic acids from different aquatic environments. Samples first are methylated with 13C-labeled diazomethane. The NMR spectra of the diazomethylated samples allow one to distinguish between methyl esters of carboxylic acids, methyl ethers of phenolic hydroxyls, and methyl ethers of phenolic hydroxyls adjacent to two substituents. Samples are then permethylated with 13C-labeled methyl iodide/NaH. 13C NMR spectra of permethylated samples show that a significant fraction of the hydroxyl groups is not methylated with diazomethane alone. In these spectra methyl ethers of carbohydrate and aliphatic hydroxyls overlap with methyl ethers of phenolic hydroxyls. Side reactions of the methyltion procedure including carbon methylation in the CH3I/NaH procedure, are also examined. Humic and fulvic acids from bog, swamp, groundwater, and lake waters showssome differences in their distribution of hydroxyl groups, mainly in the concentrations of phenolic hydroxyls, which may be attributed to their different biogeochemical origins. ?? 1987.

  20. Neuroprotective effects of caffeine in MPTP model of Parkinson's disease: A (13)C NMR study.

    PubMed

    Bagga, Puneet; Chugani, Anup N; Patel, Anant B

    2016-01-01

    Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of nigrostriatal dopaminergic neurons with an accompanying neuroinflammation leading to loss of dopamine in the basal ganglia. Caffeine, a well-known A2A receptor antagonist is reported to slow down the neuroinflammation caused by activated microglia and reduce the extracellular glutamate in the brain. In this study, we have evaluated the neuroprotective effect of caffeine in the MPTP model of PD by monitoring the region specific cerebral energy metabolism. Adult C57BL6 mice were treated with caffeine (30 mg/kg, i.p.) 30 min prior to MPTP (25 mg/kg, i.p.) administration for 8 days. The paw grip strength of mice was assessed in order to evaluate the motor function after various treatments. For metabolic studies, mice were infused with [1,6-(13)C2]glucose, and (13)C labeling of amino acids was monitored using ex vivo(1)H-[(13)C]-NMR spectroscopy. The paw grip strength was found to be reduced following the MPTP treatment. The caffeine pretreatment showed significant protection against the reduction of paw grip strength in MPTP treated mice. The levels of GABA and myo-inositol were found to be elevated in the striatum of MPTP treated mice. The (13)C labeling of GluC4, GABAC2 and GlnC4 from [1,6-(13)C2]glucose was decreased in the cerebral cortex, striatum, olfactory bulb, thalamus and cerebellum suggesting impaired glutamatergic and GABAergic neuronal activity and neurotransmission of the MPTP treated mice. Most interestingly, the pretreatment of caffeine maintained the (13)C labeling of amino acids to the control values in cortical, olfactory bulb and cerebellum regions while it partially retained in striatal and thalamic regions in MPTP treated mice. The pretreatment of caffeine provides a partial neuro-protection against severe striatal degeneration in the MPTP model of PD. PMID:26626997

  1. Hyperpolarized 13C NMR lifetimes in the liquid-state: relating structures and T1 relaxation times

    NASA Astrophysics Data System (ADS)

    Parish, Christopher; Niedbalski, Peter; Hashami, Zohreh; Fidelino, Leila; Kovacs, Zoltan; Lumata, Lloyd

    Among the various attempts to solve the insensitivity problem in nuclear magnetic resonance (NMR), the physics-based technique dissolution dynamic nuclear polarization (DNP) is probably the most successful method of hyperpolarization or amplifying NMR signals. Using this technique, liquid-state NMR signal enhancements of several thousand-fold are expected for low-gamma nuclei such as carbon-13. The lifetimes of these hyperpolarized 13C NMR signals are directly related to their 13C spin-lattice relaxation times T1. Depending upon the 13C isotopic location, the lifetimes of hyperpolarized 13C compounds can range from a few seconds to minutes. In this study, we have investigated the hyperpolarized 13C NMR lifetimes of several 13C compounds with various chemical structures from glucose, acetate, citric acid, naphthalene to tetramethylallene and their deuterated analogs at 9.4 T and 25 deg C. Our results show that the 13C T1s of these compounds can range from a few seconds to more than 60 s at this field. Correlations between the chemical structures and T1 relaxation times will be discussed and corresponding implications of these results on 13C DNP experiments will be revealed. US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

  2. Direct uptake of organic carbon by grass roots and allocation in leaves and phytoliths: 13C labeling evidence

    NASA Astrophysics Data System (ADS)

    Alexandre, A.; Balesdent, J.; Cazevieille, P.; Chevassus-Rosset, C.; Signoret, P.; Mazur, J.-C.; Harutyunyan, A.; Doelsch, E.; Basile-Doelsch, I.; Miche, H.; Santos, G. M.

    2015-12-01

    In the rhizosphere, the uptake of low molecular weight carbon (C) and nitrogen (N) by plant roots has been well documented. While organic N uptake relatively to total uptake is important, organic C uptake is supposed to be low relatively to the plant's C budget. Recently, radiocarbon analyses demonstrated that a fraction of C from the soil was occluded in amorphous silica micrometric particles that precipitate in plant cells (phytoliths). Here, we investigated whether and in which extent organic C absorbed by grass roots, under the form of either intact amino acids (AAs) or microbial metabolites, can feed the organic C occluded in phytoliths. For this purpose we added 13C- and 15N-labeled AAs to the silicon-rich hydroponic solution of the grass Festuca arundinacea. The experiment was designed to prevent C leakage from the labeled nutritive solution to the chamber atmosphere. After 14 days of growth, the 13C and 15N enrichments (13C-excess and 15N-excess) in the roots, stems and leaves, and phytoliths, as well as the 13C-excess in AAs extracted from roots and stems and leaves, were quantified relatively to a control experiment in which no labelled AAs were added. The net uptake of 13C derived from the labeled AAs supplied to the nutritive solution (AA-13C) by Festuca arundinacea represented 4.5 % of the total AA-13C supply. AA-13C fixed in the plant represented only 0.13 % of total C. However, the experimental conditions may have underestimated the extent of the process under natural and field conditions. Previous studies showed that 15N and 13C can be absorbed by the roots in several organic and inorganic forms. In the present experiment, the fact that phenylalanine and methionine, that were supplied in high amount to the nutritive solution, were more 13C-enriched than other AAs in the roots and stems and leaves strongly suggested that part of AA-13C was absorbed and translocated in its original AA form. The concentration of AA-13C represented only 0.15 % of the

  3. IRMS detection of testosterone manipulated with 13C labeled standards in human urine by removing the labeled 13C.

    PubMed

    Wang, Jingzhu; Yang, Rui; Yang, Wenning; Liu, Xin; Xing, Yanyi; Xu, Youxuan

    2014-12-10

    Isotope ratio mass spectrometry (IRMS) is applied to confirm testosterone (T) abuse by determining the carbon isotope ratios (δ(13)C value). However, (13)C labeled standards can be used to control the δ(13)C value and produce manipulated T which cannot be detected by the current method. A method was explored to remove the (13)C labeled atom at C-3 from the molecule of androsterone (Andro), the metabolite of T in urine, to produce the resultant (A-nor-5α-androstane-2,17-dione, ANAD). The difference in δ(13)C values between Andro and ANAD (Δδ(13)CAndro-ANAD, ‰) would change significantly in case manipulated T is abused. Twenty-one volunteers administered T manipulated with different (13)C labeled standards. The collected urine samples were analyzed with the established method, and the maximum value of Δδ(13)CAndro-ANAD post ingestion ranged from 3.0‰ to 8.8‰. Based on the population reference, the cut-off value of Δδ(13)CAndro-ANAD for positive result was suggested as 1.2‰. The developed method could be used to detect T manipulated with 3-(13)C labeled standards. PMID:25441891

  4. Detection of inflammatory cell function using 13C magnetic resonance spectroscopy of hyperpolarized [6-13C]-arginine

    PubMed Central

    Najac, Chloé; Chaumeil, Myriam M.; Kohanbash, Gary; Guglielmetti, Caroline; Gordon, Jeremy W.; Okada, Hideho; Ronen, Sabrina M.

    2016-01-01

    Myeloid-derived suppressor cells (MDSCs) are highly prevalent inflammatory cells that play a key role in tumor development and are considered therapeutic targets. MDSCs promote tumor growth by blocking T-cell-mediated anti-tumoral immune response through depletion of arginine that is essential for T-cell proliferation. To deplete arginine, MDSCs express high levels of arginase, which catalyzes the breakdown of arginine into urea and ornithine. Here, we developed a new hyperpolarized 13C probe, [6-13C]-arginine, to image arginase activity. We show that [6-13C]-arginine can be hyperpolarized, and hyperpolarized [13C]-urea production from [6-13C]-arginine is linearly correlated with arginase concentration in vitro. Furthermore we show that we can detect a statistically significant increase in hyperpolarized [13C]-urea production in MDSCs when compared to control bone marrow cells. This increase was associated with an increase in intracellular arginase concentration detected using a spectrophotometric assay. Hyperpolarized [6-13C]-arginine could therefore serve to image tumoral MDSC function and more broadly M2-like macrophages. PMID:27507680

  5. Anomalous 13C enrichment in modern marine organic carbon

    USGS Publications Warehouse

    Arthur, M.A.; Dean, W.E.; Claypool, G.E.

    1985-01-01

    Marine organic carbon is heavier isotopically (13C enriched) than most land-plant or terrestrial organic C1. Accordingly, ??13C values of organic C in modern marine sediments are routinely interpreted in terms of the relative proportions of marine and terrestrial sources of the preserved organic matter2,3. When independent geochemical techniques are used to evaluate the source of organic matter in Cretaceous or older rocks, those rocks containing mostly marine organic C are found typically to have lighter (more-negative) ??13C values than rocks containing mostly terrestrial organic C. Here we conclude that marine photosynthesis in mid-Cretaceous and earlier oceans generally resulted in a greater fractionation of C isotopes and produced organic C having lighter ??13C values. Modern marine photosynthesis may be occurring under unusual geological conditions (higher oceanic primary production rates, lower PCO2) that limit dissolved CO2 availability and minimize carbon isotope fractionation4. ?? 1985 Nature Publishing Group.

  6. Field measurements of del13C in ecosystem respiration

    NASA Astrophysics Data System (ADS)

    van Asperen, Hella; Sabbatini, Simone; Nicolini, Giacomo; Warneke, Thorsten; Papale, Dario; Notholt, Justus

    2014-05-01

    Stable carbon isotope del13C-measurements are extensively used to study ecological and biogeochemical processes in ecosystems. Above terrestrial ecosystems, atmospheric del13C can vary largely due to photosynthetic fractionation. Photosynthetic processes prefer the uptake of the lighter isotope 12C (in CO2), thereby enriching the atmosphere in 13C and depleting the ecosystem carbon. At night, when ecosystem respiratory fluxes are dominant, 13C-depleted CO2 is respired and thereby depletes the atmospheric del13C-content. Different ecosystems and different parts of one ecosystem (type of plant, leaves, and roots) fractionate and respire with a different del13C-ratio signature. By determining the del13C-signature of ecosystem respiration in temporal and spatial scale, an analysis can be made of the composition of respiratory sources of the ecosystem. A field study at a dry cropland after harvest (province of Viterbo, Lazio, Italy) was performed in the summer of 2013. A FTIR (Fourier Transform Infrared Spectrometer) was set up to continuously measure CO2-, CH4-, N2O-, CO- and del13C-concentrations. The FTIR was connected to 2 different flux measurements systems: a Flux Gradient system (sampling every half hour at 1.3m and 4.2m) and 2 flux chambers (measured every hour), providing a continuous data set of the biosphere-atmosphere gas fluxes and of the gas concentrations at different heights. Keeling plot intercept values of respiratory CO2, measured by the Flux Gradient system at night, were determined to be between -25‰ and -20‰. Keeling plot intercept values of respiratory CO2, measured by the flux chamber system, varied between -24‰ and -29‰, and showed a clear diurnal pattern, suggesting different (dominant) respiratory processes between day and night.

  7. Abundance anomaly of the 13C species of CCH

    NASA Astrophysics Data System (ADS)

    Sakai, N.; Saruwatari, O.; Sakai, T.; Takano, S.; Yamamoto, S.

    2010-03-01

    Aims: We have observed the N = 1-0 lines of CCH and its 13C isotopic species toward a cold dark cloud, TMC-1 and a star-forming region, L1527, to investigate the 13C abundances and formation pathways of CCH. Methods: The observations have been carried out with the IRAM 30 m telescope. Results: We have successfully detected the lines of 13CCH and C13CH toward the both sources and found a significant intensity difference between the two 13C isotopic species. The [C13CH] /[13CCH] abundance ratios are 1.6 ± 0.4 (3σ) and 1.6 ± 0.1 (3σ) for TMC-1 and L1527, respectively. The abundance difference between C13CH and 13CCH means that the two carbon atoms of CCH are not equivalent in the formation pathway. On the other hand, the [CCH]/[C13CH] and [CCH]/[13CCH] ratios are evaluated to be larger than 170 and 250 toward TMC-1, and to be larger than 80 and 135 toward L1527, respectively. Therefore, both of the 13C species are significantly diluted in comparison with the interstellar 12C/13C ratio of 60. The dilution is discussed in terms of a behavior of 13C in molecular clouds.

  8. 1H and 13C resonance designation of antimycin A1 by two-dimensional NMR spectroscopy

    USGS Publications Warehouse

    Abidi, S.L.; Adams, B.R.

    1987-01-01

    Complete 1H and 13C resonance assignments of antimycin A1 were accomplished by two-dimensional NMR techniques, viz. 1H homonuclear COSY correlation, heteronuclear 13C-1H chemical shift correlation and long-range heteronuclear 13C-1H COLOC correlation. Antimycin A1 was found to consist of two isomeric components in a 2:1 ratio based on NMR spectroscopic evidence. The structure of the major component was newly assigned as the 8-isopentanoic acid ester. The spectra of the minor component were consistent with the known structure of antimycin A1.

  9. In vivo 13C NMR metabolite profiling: potential for understanding and assessing conifer seed quality.

    PubMed

    Terskikh, Victor V; Feurtado, J Allan; Borchardt, Shane; Giblin, Michael; Abrams, Suzanne R; Kermode, Allison R

    2005-08-01

    High-resolution 13C MAS NMR spectroscopy was used to profile a range of primary and secondary metabolites in vivo in intact whole seeds of eight different conifer species native to North America, including six of the Pinaceae family and two of the Cupressaceae family. In vivo 13C NMR provided information on the total seed oil content and fatty acid composition of the major storage lipids in a non-destructive manner. In addition, a number of monoterpenes were identified in the 13C NMR spectra of conifer seeds containing oleoresin; these compounds showed marked variability in individual seeds of Pacific silver fir within the same seed lot. In imbibed conifer seeds, the 13C NMR spectra showed the presence of considerable amounts of dissolved sucrose presumed to play a protective role in the desiccation-tolerance of seeds. The free amino acids arginine and asparagine, generated as a result of storage protein mobilization, were detected in vivo during seed germination and early seedling growth. The potential for NMR to profile metabolites in a non-destructive manner in single conifer seeds and seed populations is discussed. It is a powerful tool to evaluate seed quality because of its ability to assess reserve accumulation during seed development or at seed maturity; it can also be used to monitor reserve mobilization, which is critical for seedling emergence. PMID:15996983

  10. Dynamic 13C NMR analysis of oxidative metabolism in the in vivo canine myocardium.

    PubMed

    Robitaille, P M; Rath, D P; Abduljalil, A M; O'Donnell, J M; Jiang, Z; Zhang, H; Hamlin, R L

    1993-12-15

    Oxidative metabolism in the in vivo canine myocardium was studied noninvasively using 13C-enriched acetate and non-steady state 13C NMR techniques. Under low workload conditions, the myocardium oxidized the infused [2-13C]acetate and incorporated the labeled carbon into the glutamate pool as expected. This conclusion stems from the rapid enrichment of the C-2, C-3, and C-4 carbons of glutamic acid both under in vivo conditions and in extracts. Surprisingly, [2-13C]acetate uptake was not observed at high workloads as reflected by an absence of glutamate pool enrichment at these rate pressure products. Rather, the myocardium selected its substrate from an endogenous pool. Since free acetate can directly cross the inner mitochondrial membrane and be converted to acetyl-CoA through acetyl-CoA synthetase, these results support workload-dependent regulation of substrate access to the mitochondrial CoASH pool. As such, we advance the hypothesis that the selection of substrate for condensation with CoASH and subsequent oxidation in the tricarboxylic acid cycle is regulated kinetically through the Km values of the appropriate condensation enzymes and through the absolute levels of free CoASH in the mitochondria. PMID:8253751

  11. Trials of novel 13C-urea-containing capsule for more economic and sensitive diagnosis of Helicobacter pylori infection in human subjects.

    PubMed

    Yong, Chul Soon; Kim, Yong-Il; Park, San-Man; Kwon, Rham; Han, Hong-Hee; Park, Jung Gil; Yang, Chan-Yoo; Kim, Jung-Ae; Yoo, Bong-Kyu; Rhee, Jong-Dal; Choi, Han-Gon

    2006-10-01

    To develop a 13C-urea-containing capsule for more economic and sensitive diagnosis of Helicobacter pylori infection, the 13C-urea-containing capsules were prepared with various additives such as polyethylene glycol, microcrystalline cellulose, sodium lauryl sulfate and citric acid. Their dissolution test and 13C-urea Breath Test in human volunteers were then performed. Polyethylene glycol increased the initial dissolution rates of urea and difference delta 13C values from 13C-urea, while microcrystalline cellulose and sodium lauryl sulfate decreased them. Irrespective of addition of citric acid, the compositions with polyethylene glycol showed higher values from 13C-urea compared to a commercial 76 mg 13C-urea-containing capsule due to higher initial dissolution rate. The capsules with 38 mg 13C-urea and 1.9 mg polyethylene glycol, which showed higher Helicobacter pylori-positive value of about 8 per thousand at 10 min, improved the sensitivity of 13C-urea in human volunteers. Thus, the 13C-urea-containing capsule with polyethylene glycol would be a more economical and sensitive preparation for diagnosis of Helicobacter pylori infection. PMID:17121183

  12. A 13C-NMR study of azacryptand complexes.

    PubMed

    Wild, Aljoscha A C; Fennell, Kevin; Morgan, Grace G; Hewage, Chandralal M; Malthouse, J Paul G

    2014-09-28

    An azacryptand has been solubilised in aqueous media containing 50% (v/v) dimethyl sulphoxide. (13)C-NMR has been used to determine how the azacryptand is affected by zinc binding at pH 10. Using (13)C-NMR and (13)C-enriched bicarbonate we have been able to observe the formation of 4 different carbamate derivatives of the azacryptand at pH 10. The azacryptand was shown to solubilise zinc or cadmium at alkaline pHs. Two moles of zinc are bound per mole of azacryptand and this complex binds 1 mole of carbonate. By replacing the zinc with cadmium-113 we have shown that the (13)C-NMR signal of the (13)C-enriched carbon of the bound carbonate is split into two triplets at 2.2 °C. This shows that two cadmium complexes are formed and in each of these complexes the carbonate group is bound by two magnetically equivalent metal ions. It also demonstrates that these cadmium complexes are not in fast exchange. From temperature studies we show that in the zinc complexes both complexes are in fast exchange with each other but are in slow exchange with free bicarbonate. HOESY is used to determine the position of the carbonate carbon in the complex. The solution and crystal structures of the zinc-carbonate-azacryptand complexes are compared. PMID:25091182

  13. A scientific workflow framework for (13)C metabolic flux analysis.

    PubMed

    Dalman, Tolga; Wiechert, Wolfgang; Nöh, Katharina

    2016-08-20

    Metabolic flux analysis (MFA) with (13)C labeling data is a high-precision technique to quantify intracellular reaction rates (fluxes). One of the major challenges of (13)C MFA is the interactivity of the computational workflow according to which the fluxes are determined from the input data (metabolic network model, labeling data, and physiological rates). Here, the workflow assembly is inevitably determined by the scientist who has to consider interacting biological, experimental, and computational aspects. Decision-making is context dependent and requires expertise, rendering an automated evaluation process hardly possible. Here, we present a scientific workflow framework (SWF) for creating, executing, and controlling on demand (13)C MFA workflows. (13)C MFA-specific tools and libraries, such as the high-performance simulation toolbox 13CFLUX2, are wrapped as web services and thereby integrated into a service-oriented architecture. Besides workflow steering, the SWF features transparent provenance collection and enables full flexibility for ad hoc scripting solutions. To handle compute-intensive tasks, cloud computing is supported. We demonstrate how the challenges posed by (13)C MFA workflows can be solved with our approach on the basis of two proof-of-concept use cases. PMID:26721184

  14. 13C NMR spectroscopy applications to brain energy metabolism

    PubMed Central

    Rodrigues, Tiago B.; Valette, Julien; Bouzier-Sore, Anne-Karine

    2013-01-01

    13C nuclear magnetic resonance (NMR) spectroscopy is the method of choice for studying brain metabolism. Indeed, the most convincing data obtained to decipher metabolic exchanges between neurons and astrocytes have been obtained using this technique, thus illustrating its power. It may be difficult for non-specialists, however, to grasp thefull implication of data presented in articles written by spectroscopists. The aim of the review is, therefore, to provide a fundamental understanding of this topic to facilitate the non-specialists in their reading of this literature. In the first part of this review, we present the metabolic fate of 13C-labeled substrates in the brain in a detailed way, including an overview of some general neurochemical principles. We also address and compare the various spectroscopic strategies that can be used to study brain metabolism. Then, we provide an overview of the 13C NMR experiments performed to analyze both intracellular and intercellular metabolic fluxes. More particularly, the role of lactate as a potential energy substrate for neurons is discussed in the light of 13C NMR data. Finally, new perspectives and applications offered by 13C hyperpolarization are described. PMID:24367329

  15. Inclusion of 13C and D in protonated acetylene

    NASA Astrophysics Data System (ADS)

    Fortenberry, Ryan C.; Roueff, Evelyne; Lee, Timothy J.

    2016-04-01

    The rovibrational spectrum of cyclic, protonated acetylene has been established. The improvement in modern telescopes coupled with the different branching ratios in reaction models welcomes study of 13C-substitution for C2H3+. Quartic force fields (QFFs) have been previously utilized to predict the antisymmetric HCCH stretch in standard c-C2H3+ to within 0.1 cm-1 of experiment and are employed here to generate rovibrational insights for the 13C isotopologues. The zero-point energies are also given for the cyclic and 'Y'-shaped isomers for both 13C and D substitutions. Vibrational intensities and the dipole moments are provided in order to characterize more fully this simple cation.

  16. {sup 13}C relaxation in an RNA hairpin

    SciTech Connect

    King, G.C. |; Akratos, C.; Xi, Z.; Michnica, M.J.

    1994-12-01

    This initial survey of {sup 13}C relaxation in the {triangle}TAR RNA element has generated a number of interesting results that should prove generally useful for future studies. The most readily comparable study in the literature monitored {sup 13}C relaxation of the methyl groups from unusual bases in tRNA{sup Phe}. The study, which used T{sub 1} and NOE data only, reported order parameters for the methyl group axis that ranged between 0.51 and 0.97-a range similar to that observed here. However, they reported a breakdown of the standard order parameter analysis at higher (118-MHz {sup 13}C) frequencies, which should serve to emphasize the need for a thorough exploration of suitable motional models.

  17. Magnetic Resonance Imaging with Hyperpolarized 13C Contrast Agents

    NASA Astrophysics Data System (ADS)

    Gordon, Jeremy W.

    Hyperpolarized 13C substrates offer the potential to non-invasively image metabolism and enzymatic activity. However, hyperpolarization introduces a number of difficulties, and imaging is hampered by non-equilibrium magnetization and the need for spectral encoding. There is therefore a need for fast and RF efficient spectral imaging techniques. This work presents a number of new methods that can be used to improve polarization, increase RF efficiency and improve modeling accuracy in hyperpolarized 13C experiments. In particular, a novel encoding and reconstruction algorithm is presented that can generate spatially and spectrally resolved images with a single RF excitation and echo time. This reconstruction framework increases data acquisition efficiency, enabling accelerated acquisition speed, preserved polarization, and/or improved temporal or spatial resolution. Overall, the methods enumerated in this dissertation have the potential to improve modeling accuracy and to mitigate the conventional tradeoffs between SNR, spatial resolution, and temporal resolution that govern image quality in hyperpolarized 13C experiments.

  18. Study of molecular interactions with 13C DNP-NMR

    NASA Astrophysics Data System (ADS)

    Lerche, Mathilde H.; Meier, Sebastian; Jensen, Pernille R.; Baumann, Herbert; Petersen, Bent O.; Karlsson, Magnus; Duus, Jens Ø.; Ardenkjær-Larsen, Jan H.

    2010-03-01

    NMR spectroscopy is an established, versatile technique for the detection of molecular interactions, even when these interactions are weak. Signal enhancement by several orders of magnitude through dynamic nuclear polarization alleviates several practical limitations of NMR-based interaction studies. This enhanced non-equilibrium polarization contributes sensitivity for the detection of molecular interactions in a single NMR transient. We show that direct 13C NMR ligand binding studies at natural isotopic abundance of 13C gets feasible in this way. Resultant screens are easy to interpret and can be performed at 13C concentrations below μM. In addition to such ligand-detected studies of molecular interaction, ligand binding can be assessed and quantified with enzymatic assays that employ hyperpolarized substrates at varying enzyme inhibitor concentrations. The physical labeling of nuclear spins by hyperpolarization thus provides the opportunity to devise fast novel in vitro experiments with low material requirement and without the need for synthetic modifications of target or ligands.

  19. Regioselective syntheses of [13C]4-labelled sodium 1-carboxy-2-(2-ethylhexyloxycarbonyl)ethanesulfonate and sodium 2-carboxy-1-(2-ethylhexyloxycarbonyl)ethanesulfonate from [13C]4-maleic anhydride.

    PubMed

    Barsamian, Adam L; Perkins, Matt J; Field, Jennifer A; Blakemore, Paul R

    2014-05-15

    The entitled monohydrolysis products, also known as α-ethylhexyl and β-ethylhexyl sulfosuccinate (EHSS), of the surfactant diisooctyl sulfosuccinate (DOSS) were synthesized in stable isotope-labelled form from [(13)C]4 -maleic anhydride. Sodium [(13)C]4 -1-carboxy-2-(2-ethylhexyloxycarbonyl)ethanesulfonate (α-EHSS) was prepared by the method of Larpent by reaction of 2-ethylhexan-1-ol with [(13)C]4 -maleic anhydride followed by regioselective conjugate addition of sodium bisulfite to the resulting monoester (38% overall yield). The regiochemical outcome of bisulfite addition was confirmed by a combination of (13)C/(13)C (incredible natural abundance double quantum transfer) and (1)H/(13)C (heteronuclear multiple-bond correlation (HMBC)) NMR spectral correlation experiments. Sodium [(13)C]4 -2-carboxy-1-(2-ethylhexyloxycarbonyl)ethanesulfonate (β-EHSS) was prepared in four steps by reaction of 4-methoxybenzyl alcohol with [(13)C]4 -maleic anhydride, regioselective sodium bisulfite addition, N,N'-dicyclohexylcarbodiimide-mediated esterification with 2-ethylhexan-1-ol, and p-methoxybenzyl ester deprotection with trifluoroacetic acid (13% overall yield). The regiochemical outcome of the second synthesis was confirmed by a combination of (1)JCC scalar coupling constant analysis and (1)H/(13)C (HMBC) NMR spectral correlation. The materials prepared are required as internal standards for the liquid chromatography-mass spectrometry (LC-MS)/MS trace analysis of the degradation products of DOSS, the anionic surfactant found in Corexit, the oil dispersant used during emergency response efforts connected to the Deepwater Horizon oil spill of April 2010. PMID:24700711

  20. Recent advances in mapping environmental microbial metabolisms through 13C isotopic fingerprints.

    PubMed

    Tang, Joseph Kuo-Hsiang; You, Le; Blankenship, Robert E; Tang, Yinjie J

    2012-11-01

    After feeding microbes with a defined (13)C substrate, unique isotopic patterns (isotopic fingerprints) can be formed in their metabolic products. Such labelling information not only can provide novel insights into functional pathways but also can determine absolute carbon fluxes through the metabolic network via metabolic modelling approaches. This technique has been used for finding pathways that may have been mis-annotated in the past, elucidating new enzyme functions, and investigating cell metabolisms in microbial communities. In this review paper, we summarize the applications of (13)C approaches to analyse novel cell metabolisms for the past 3 years. The isotopic fingerprints (defined as unique isotopomers useful for pathway identifications) have revealed the operations of the Entner-Doudoroff pathway, the reverse tricarboxylic acid cycle, new enzymes for biosynthesis of central metabolites, diverse respiration routes in phototrophic metabolism, co-metabolism of carbon nutrients and novel CO(2) fixation pathways. This review also discusses new isotopic methods to map carbon fluxes in global metabolisms, as well as potential factors influencing the metabolic flux quantification (e.g. metabolite channelling, the isotopic purity of (13)C substrates and the isotopic effect). Although (13)C labelling is not applicable to all biological systems (e.g. microbial communities), recent studies have shown that this method has a significant value in functional characterization of poorly understood micro-organisms, including species relevant for biotechnology and human health. PMID:22896564

  1. Recent advances in mapping environmental microbial metabolisms through 13C isotopic fingerprints

    PubMed Central

    Tang, Joseph Kuo-Hsiang; You, Le; Blankenship, Robert E.; Tang, Yinjie J.

    2012-01-01

    After feeding microbes with a defined 13C substrate, unique isotopic patterns (isotopic fingerprints) can be formed in their metabolic products. Such labelling information not only can provide novel insights into functional pathways but also can determine absolute carbon fluxes through the metabolic network via metabolic modelling approaches. This technique has been used for finding pathways that may have been mis-annotated in the past, elucidating new enzyme functions, and investigating cell metabolisms in microbial communities. In this review paper, we summarize the applications of 13C approaches to analyse novel cell metabolisms for the past 3 years. The isotopic fingerprints (defined as unique isotopomers useful for pathway identifications) have revealed the operations of the Entner–Doudoroff pathway, the reverse tricarboxylic acid cycle, new enzymes for biosynthesis of central metabolites, diverse respiration routes in phototrophic metabolism, co-metabolism of carbon nutrients and novel CO2 fixation pathways. This review also discusses new isotopic methods to map carbon fluxes in global metabolisms, as well as potential factors influencing the metabolic flux quantification (e.g. metabolite channelling, the isotopic purity of 13C substrates and the isotopic effect). Although 13C labelling is not applicable to all biological systems (e.g. microbial communities), recent studies have shown that this method has a significant value in functional characterization of poorly understood micro-organisms, including species relevant for biotechnology and human health. PMID:22896564

  2. Diatom Frustule-Bound δ13c Measurements and Reconstruction of Εp

    NASA Astrophysics Data System (ADS)

    Stoll, H. M.; Mejia Ramirez, L. M.; Mendez-Vicente, A.; Abrevaya, L.; Bolton, C. T.; Anderson, R. F.

    2014-12-01

    Diatom frustules contain embedded organic matter such as amino acids, which may offer a potential phase for measuring the carbon isotopic fractionation during marine photosynthesis (ɛp). We describe optimal sample preparation methods for cleaning external organic matter and separating frustules into various size classes while reducing significance of opal from radiolaria and silicoflagellates. Analysis of discrete separated fractions of diatom opal from each sediment sample is facilitated by our new method for analysis of very small sample sizes using NanoEA with cryotrapping of evolved CO2. We evaluate the fidelity with which frustule-bound organic matter captures the variation in ɛp by comparing δ13C of frustule-bound organic matter with that of total cellular carbon in diatoms grown in culture, and by comparing the δ13C of frustule-bound organic matter in core tops with that of δ13C of diatom-produced biomarkers in the overlying water column. In core-top transects, frustule-bound δ13C is consistent with strong growth rate control over fractionation during photosynthesis (ɛp). Finally, we evaluate the temporal trends in carbon isotopic fractionation during photosynthesis since the Late Miocene in samples from the Eastern Equatorial Pacific.

  3. Determination of the δ13C of dissolved inorganic carbon in water; RSIL lab code 1710

    USGS Publications Warehouse

    Singleton, Glenda L.; Revesz, Kinga; Coplen, Tyler B.

    2012-01-01

    The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 1710 is to present a method to determine the δ13C of dissolved inorganic carbon (DIC) of water. The DIC of water is precipitated using ammoniacal strontium chloride (SrCl2) solution to form strontium carbonate (SrCO3). The δ13C is analyzed by reacting SrCO3 with 100-percent phosphoric acid (H3PO4) to liberate carbon quantitatively as carbon dioxide (CO2), which is collected, purified by vacuum sublimation, and analyzed by dual inlet isotope-ratio mass spectrometry (DI-IRMS). The DI-IRMS is a DuPont double-focusing mass spectrometer. One ion beam passes through a slit in a forward collector and is collected in the rear collector. The other measurable ion beams are collected in the front collector. By changing the ion-accelerating voltage under computer control, the instrument is capable of measuring mass/charge (m/z) 45 or 46 in the rear collector and m/z 44 and 46 or 44 and 45, respectively, in the front collector. The ion beams from these m/z values are as follows: m/z 44 = CO2 = 12C16O16O, m/z 45 = CO2 = 13C16O16O primarily, and m/z 46 = CO2 = 12C16O18O primarily. The data acquisition and control software calculates δ13C values.

  4. Measuring (13)C/(15)N chemical shift anisotropy in [(13)C,(15)N] uniformly enriched proteins using CSA amplification.

    PubMed

    Hung, Ivan; Ge, Yuwei; Liu, Xiaoli; Liu, Mali; Li, Conggang; Gan, Zhehong

    2015-11-01

    Extended chemical shift anisotropy amplification (xCSA) is applied for measuring (13)C/(15)N chemical shift anisotropy (CSA) of uniformly labeled proteins under magic-angle spinning (MAS). The amplification sequence consists of a sequence of π-pulses that repetitively interrupt MAS averaging of the CSA interaction. The timing of the pulses is designed to generate amplified spinning sideband manifolds which can be fitted to extract CSA parameters. The (13)C/(13)C homonuclear dipolar interactions are not affected by the π-pulses due to the bilinear nature of the spin operators and are averaged by MAS in the xCSA experiment. These features make the constant evolution-time experiment suitable for measuring CSA of uniformly labeled samples. The incorporation of xCSA with multi-dimensional (13)C/(15)N correlation is demonstrated with a GB1 protein sample as a model system for measuring (13)C/(15)N CSA of all backbone (15)NH, (13)CA and (13)CO sites. PMID:26404770

  5. Influence of 13C isotopic labeling location of 13C DNP of acetate using TEMPO free radical

    NASA Astrophysics Data System (ADS)

    Parish, Christopher; Niedbalski, Peter; Lumata, Lloyd

    2015-03-01

    Dynamic nuclear polarization (DNP) via the dissolution method enhances the liquid-state magnetic resonance (NMR or MRI) signals of insensitive nuclear spins by at least 10,000-fold. The basis for all these signal enhancements at room temperature is the polarization transfer from the electrons to nuclear spins at cryogenic temperature and high magnetic field. In this work, we have studied the influence of the location of 13C isotopic labeling on the DNP of sodium acetate at 3.35 T and 1.4 K using a wide ESR linewidth free radical 4-oxo-TEMPO. The carbonyl [1-13C]acetate spins produced a polarization level that is almost twice that of the methyl [2-13C]acetate spins. On the other hand, the polarization of the methyl 13C spins doubled to reach the level of [1-13C]acetate when the methyl group was deuterated. Meanwhile, the solid-state nuclear relaxation of these samples are the same and do not correlate with the polarization levels. These behavior implies that the nuclear relaxation for these samples is dominated by the contribution from the free radicals and the polarization levels can be explained by a thermodynamic picture of DNP.

  6. Measuring doubly 13C-substituted ethane by mass spectrometry

    NASA Astrophysics Data System (ADS)

    Clog, M.; Ling, C.; Eiler, J. M.

    2012-12-01

    Ethane (C2H6) is present in non-negligible amounts in most natural gas reservoirs and is used to produce ethylene for petrochemical industries. It is one of the by-products of lipid metabolism and is the arguably simplest molecule that can manifest multiple 13C substitutions. There are several plausible controls on the relative abundances of 13C2H6 in natural gases: thermodynamically controlled homogeneous isotope exchange reactions analogous to those behind carbonate clumped isotope thermometry; inheritance from larger biomolecules that under thermal degradation to produce natural gas; mixing of natural gases that differ markedly in bulk isotopic composition; or combinations of these and/or other, less expected fractionations. There is little basis for predicting which of these will dominate in natural samples. Here, we focus on an analytical techniques that will provide the avenue for exploring these phenomena. The method is based on high-resolution gas source isotope ratio mass spectrometry, using the Thermo 253-Ultra (a new prototype mass spectrometer). This instrument achieves the mass resolution (M/Δ M) up to 27,000, permitting separation of the isobaric interferences of potential contaminants and isotopologues of an analtye or its fragments which share a cardinal mass. We present techniques to analyze several isotopologues of molecular and fragment ions of C2H6. The critical isobaric separations for our purposes include: discrimination of 13C2H6 from 13C12CDH5 at mass 32 and separation of the 13CH3 fragment from 12CH4 at mass 16, both requiring at least a mass resolution of 20000 to make an adequate measurement. Other obvious interferences are either cleanly separated (e.g., O2, O) or accounted for by peak-stripping (CH3OH on mass 32 and NH2 on mass 16). We focus on a set of measurements which constrain: the doubly-substituted isotopologue, 13C2H6, and the 13CH3/12CH3 ratio of the methyl fragment, which constrains the bulk δ 13C. Similar methods can be

  7. The fate of (13)C-labelled and non-labelled inulin predisposed to large bowel fermentation in rats.

    PubMed

    Butts, Christine A; Paturi, Gunaranjan; Tavendale, Michael H; Hedderley, Duncan; Stoklosinski, Halina M; Herath, Thanuja D; Rosendale, Douglas; Roy, Nicole C; Monro, John A; Ansell, Juliet

    2016-04-20

    The fate of stable-isotope (13)C labelled and non-labelled inulin catabolism by the gut microbiota was assessed in a healthy rat model. Sprague-Dawley male rats were randomly assigned to diets containing either cellulose or inulin, and were fed these diets for 3 days. On day (d) 4, rats allocated to the inulin diet received (13)C-labelled inulin. The rats were then fed the respective non-labelled diets (cellulose or inulin) until sampling (d4, d5, d6, d7, d10 and d11). Post feeding of (13)C-labelled substrate, breath analysis showed that (13)C-inulin cleared from the host within a period of 36 hours. Faecal (13)C demonstrated the clearance of inulin from gut with a (13)C excess reaching maximum at 24 hours (d5) and then declining gradually. There were greater variations in caecal organic acid concentrations from d4 to d6, with higher concentrations of acetic, butyric and propionic acids observed in the rats fed inulin compared to those fed cellulose. Inulin influenced caecal microbial glycosidase activity, increased colon crypt depth, and decreased the faecal output and polysaccharide content compared to the cellulose diet. In summary, the presence of inulin in the diet positively influenced large bowel microbial fermentation. PMID:26778667

  8. Characterization of a Mixture of CO2 Adsorption Products in Hyperbranched Aminosilica Adsorbents by (13)C Solid-State NMR.

    PubMed

    Moore, Jeremy K; Sakwa-Novak, Miles A; Chaikittisilp, Watcharop; Mehta, Anil K; Conradi, Mark S; Jones, Christopher W; Hayes, Sophia E

    2015-11-17

    Hyperbranched amine polymers (HAS) grown from the mesoporous silica SBA-15 (hereafter "SBA-15-HAS") exhibit large capacities for CO2 adsorption. We have used static in situ and magic-angle spinning (MAS) ex situ (13)C nuclear magnetic resonance (NMR) to examine the adsorption of CO2 by SBA-15-HAS. (13)C NMR distinguishes the signal of gas-phase (13)CO2 from that of the chemisorbed species. HAS polymers possess primary, secondary, and tertiary amines, leading to multiple chemisorption reaction outcomes, including carbamate (RnNCOO(-)), carbamic acid (RnNCOOH), and bicarbonate (HCO3(-)) moieties. Carbamates and bicarbonate fall within a small (13)C chemical shift range (162-166 ppm), and a mixture was observed including carbamic acid and carbamate, the former disappearing upon evacuation of the sample. By examining the (13)C-(14)N dipolar coupling through low-field (B0 = 3 T) (13)C{(1)H} cross-polarization MAS NMR, carbamate is confirmed through splitting of the (13)C resonance. A third species that is either bicarbonate or a second carbamate is evident from bimodal T2 decay times of the ∼163 ppm peak, indicating the presence of two species comprising that single resonance. The mixture of products suggests that (1) the presence of amines and water leads to bicarbonate being present and/or (2) the multiple types of amine sites in HAS permit formation of chemically distinct carbamates. PMID:26477882

  9. ASSESSMENT OF CYSTEINE SYNTHESIS IN VERY LOW-BIRTH WEIGHT NEONATES USING A [13C6] GLUCOSE TRACER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cysteine is an amino acid necessary for the synthesis of all proteins, the antioxidant glutathione, and the neuromodulator taurine. Whether cysteine is an essential amino acid for premature neonates remains controversial. Using a [13C6]glucose precursor in very-low-birth weight (VLBW) premature neon...

  10. Rotary resonance recoupling of 13C- 1H dipolar interactions in magic angle spinning 13C NMR of dynamic solids

    NASA Astrophysics Data System (ADS)

    Kitchin, Simon J.; Harris, Kenneth D. M.; Aliev, Abil E.; Apperley, David C.

    2000-06-01

    Rotary resonance recoupling of heteronuclear 13C- 1H dipolar interactions in magic angle spinning solid state 13C NMR spectra (recorded under conditions of 1H decoupling at frequency ν1 and magic angle spinning at frequency νr) has been studied for three examples of molecular solids (adamantane, ferrocene and hexamethylbenzene) in which substantial molecular motion is known to occur. It is shown that when rotary resonance conditions are satisfied (i.e. ν1/νr= n, for n=1 or 2), the recoupling can lead to motionally averaged Pake-like powder patterns from which information on 13C- 1H internuclear distances and/or molecular motion can be derived.

  11. Spectral editing for in vivo 13C magnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Xiang, Yun; Shen, Jun

    2012-01-01

    In vivo detection of carboxylic/amide carbons is a promising technique for studying cerebral metabolism and neurotransmission due to the very low RF power required for proton decoupling. In the carboxylic/amide region, however, there is severe spectral overlap between acetate C1 and glutamate C5, complicating studies that use acetate as an astroglia-specific substrate. There are no known in vivo MRS techniques that can spectrally resolve acetate C1 and glutamate C5 singlets. In this study, we propose to spectrally separate acetate C1 and glutamate C5 by a two-step J-editing technique after introducing homonuclear 13C- 13C scalar coupling between carboxylic/amide carbons and aliphatic carbons. By infusing [1,2- 13C 2]acetate instead of [1- 13C]acetate the acetate doublet can be spectrally edited because of the large separation between acetate C2 and glutamate C4 in the aliphatic region. This technique can be applied to studying acetate transport and metabolism in brain in the carboxylic/amide region without spectral interference.

  12. ANALYSIS OF PERFLUORINATED CARBOXYLIC ACIDS IN SOILS II: OPTIMIZATION OF CHROMATOGRAPHY AND EXTRACTION

    EPA Science Inventory

    With the objective of detecting and quantitating low concentrations of perfluorinated carboxylic acids (PFCAs), including perfluorinated octanoic acid (PFOA), in soils, we compared the analytical suitability of liquid chromatography columns containing three different stationary p...

  13. Does the Shuram δ13C excursion record Ediacaran oxygenation?

    NASA Astrophysics Data System (ADS)

    Husson, J. M.; Maloof, A. C.; Schoene, B.; Higgins, J. A.

    2013-12-01

    The most negative carbon isotope excursion in Earth history is found in carbonate rocks of the Ediacaran Period (635-542 Ma). Known colloquially as the the 'Shuram' excursion, workers have long noted its tantalizing, broad concordance with the rise of abundant macro-scale fossils in the rock record, variously interpreted as animals, giant protists, macro-algae and lichen, and known as the 'Ediacaran Biota.' Thus, the Shuram excursion has been interpreted by many in the context of a dramatically changing redox state of the Ediacaran oceans - e.g., a result of methane cycling in a low O2 atmosphere, the final destruction of a large pool of recalcitrant dissolved organic carbon (DOC), and the step-wise oxidation of the Ediacaran oceans. More recently, diagenetic interpretations of the Shuram excursion - e.g. sedimentary in-growth of very δ13C depleted authigenic carbonates, meteoric alteration of Ediacaran carbonates, late-stage burial diagenesis - have challenged the various Ediacaran redox models. A rigorous geologic context is required to discriminate between these explanatory models, and determine whether the Shuram excursion can be used to evaluate terminal Neoproterozoic oxygenation. Here, we present chemo-stratigraphic data (δ13C, δ18O, δ44/42Ca and redox sensitive trace element abundances) from 12 measured sections of the Ediacaran-aged Wonoka Formation (Fm.) of South Australia that require a syn-depositional age for the extraordinary range of δ13C values (-12 to +4‰) observed in the formation. In some locations, the Wonoka Fm. is ~700 meters (m) of mixed shelf limestones and siliclastics that record the full 16 ‰ δ13C excursion in a remarkably consistent fashion across 100s of square kilometers of basin area. Fabric-altering diagenesis, where present, occurs at the sub-meter vertical scale, only results in sub-permil offsets in δ13C and cannot be used to explain the full δ13C excursion. In other places, the Wonoka Fm. is host to deep (1 km

  14. Microbial metabolism in soil at low temperatures: Mechanisms unraveled by position-specific 13C labeling

    NASA Astrophysics Data System (ADS)

    Bore, Ezekiel

    2016-04-01

    Microbial transformation of organic substances in soil is the most important process of the C cycle. Most of the current studies base their information about transformation of organic substances on incubation studies under laboratory conditions and thus, we have a profound knowledge on SOM transformations at ambient temperatures. However, metabolic pathway activities at low temperature are not well understood, despite the fact that the processes are relevant for many soils globally and seasonally. To analyze microbial metabolism at low soil temperatures, isotopomeres of position-specifically 13C labeled glucose were incubated at three temperature; 5, -5 -20 oC. Soils were sampled after 1, 3 and 10 days and additionally after 30 days for samples at -20 °C. The 13C from individual molecule position was quantifed in respired CO2, bulk soil, extractable organic C and extractable microbial biomass by chloroform fumigation extraction (CFE) and cell membranes of microbial communities classified by 13C phospholipid fatty acid (PLFA) analysis. 13CO2 released showed a dominance of the flux from C-1 position at 5 °C. Consequently, at 5 °C, pentose phosphate pathway activity is a dominant metabolic pathway of glucose metabolization. In contrast to -5 °C and -20 oC, metabolic behaviors completely switched towards a preferential respiration of the glucose C-4 position. With decreasing temperature, microorganism strongly shifted towards metabolization of glucose via glycolysis which indicates a switch to cellular maintenance. High recoveries of 13C in extractable microbial biomass at -5 °C indicates optimal growth condition for the microorganisms. PLFA analysis showed high incorporation of 13C into Gram negative bacteria at 5 °C but decreased with temperature. Gram positive bacteria out-competed Gram negatives with decreasing temperature. This study revealed a remarkable microbial activity at temperatures below 0 °C, differing significantly from that at ambient

  15. Optical hyperpolarization of 13C nuclear spins in nanodiamond ensembles

    NASA Astrophysics Data System (ADS)

    Chen, Q.; Schwarz, I.; Jelezko, F.; Retzker, A.; Plenio, M. B.

    2015-11-01

    Dynamical nuclear polarization holds the key for orders of magnitude enhancements of nuclear magnetic resonance signals which, in turn, would enable a wide range of novel applications in biomedical sciences. However, current implementations of DNP require cryogenic temperatures and long times for achieving high polarization. Here we propose and analyze in detail protocols that can achieve rapid hyperpolarization of 13C nuclear spins in randomly oriented ensembles of nanodiamonds at room temperature. Our protocols exploit a combination of optical polarization of electron spins in nitrogen-vacancy centers and the transfer of this polarization to 13C nuclei by means of microwave control to overcome the severe challenges that are posed by the random orientation of the nanodiamonds and their nitrogen-vacancy centers. Specifically, these random orientations result in exceedingly large energy variations of the electron spin levels that render the polarization and coherent control of the nitrogen-vacancy center electron spins as well as the control of their coherent interaction with the surrounding 13C nuclear spins highly inefficient. We address these challenges by a combination of an off-resonant microwave double resonance scheme in conjunction with a realization of the integrated solid effect which, together with adiabatic rotations of external magnetic fields or rotations of nanodiamonds, leads to a protocol that achieves high levels of hyperpolarization of the entire nuclear-spin bath in a randomly oriented ensemble of nanodiamonds even at room temperature. This hyperpolarization together with the long nuclear-spin polarization lifetimes in nanodiamonds and the relatively high density of 13C nuclei has the potential to result in a major signal enhancement in 13C nuclear magnetic resonance imaging and suggests functionalized and hyperpolarized nanodiamonds as a unique probe for molecular imaging both in vitro and in vivo.

  16. Attenuated gastric distress but no benefit to performance with adaptation to octanoate-rich esterified oils in well-trained male cyclists.

    PubMed

    Thorburn, Megan S; Vistisen, Bodil; Thorp, Rhys M; Rockell, Mike J; Jeukendrup, Asker E; Xu, Xuebing; Rowlands, David S

    2006-12-01

    We investigated the effects of modifying a normal dietary fatty acid composition and ingestion of high-fat exercise supplements on gastrointestinal distress, substrate oxidation, and endurance cycling performance. Nine well-trained male cyclists completed a randomized triple-crossover comprising a 2-wk diet high in octanoate-rich esterified oil (MCFA) or twice long-chain fatty acids (LCFA). Following the diets, participants performed 3-h of cycling at 50% of peak power followed by 10 maximal sprints while ingesting either 1) a carbohydrate (CHO)+MCFA-rich oil emulsion after the 2-wk MCFA-rich dietary condition (MC-MC, Intervention) and 2) after one of the LCFA-rich dietary conditions (LC-MC, Placebo) or 3) CHO only following a LCFA-rich diet (LC-CHO, Control). During the 3-h ride MCFA-adaptation decreased octanoic-acid oxidation by 24% (90% confidence interval: 14-34%). The CHO+MCFA-rich oil emulsion reduced endogenous fat oxidation by 61% (33-89%) and 110% (89-131%) in the MC-MC and LC-MC conditions, respectively, and MCFA-adaptation reduced endogenous-carbohydrate oxidation by 10% (-3-23%). MCFA-adaptation attenuated gastrointestinal distress and nausea during the sprints, but the effect of the oil emulsion was to lower sprint power by 10.9% (7.7-14.1%) in the LC-MC condition and by 7.1% (5.7-8.5%) in the MC-MC condition, relative to the LC-CHO control; every one unit increase in nausea decreased mean power by 6.0 W (3.2-8.8 W). We conclude that despite some attenuation of endogenous-carbohydrate oxidation and gastric distress following adaptation to a MCFA-rich diet, repeat sprint performance was substantially impaired in response to the ingestion of a CHO+MCFA-rich oil emulsion. PMID:16840580

  17. Modulation of pyruvate dehydrogenase kinase activity in cultured hepatocytes by glucagon and n-octanoate.

    PubMed Central

    Fatania, H R; Vary, T C; Randle, P J

    1986-01-01

    The activity of pyruvate dehydrogenase kinase in extracts of mitochondria from rat hepatocytes cultured for 21 h in medium 199 was increased 2.5-fold by the presence of 55 nM-glucagon and 1 mM-sodium n-octanoate in the culture medium. The change was comparable with that induced in vivo by 48 h starvation. The potential contribution of branched-chain complex to estimates of PDH-complex activity in rat liver mitochondria has been defined. PMID:3707545

  18. Decarboxylation of [1-(13)C]leucine by hydroxyl radicals.

    PubMed

    Guitton, J; Tinardon, F; Lamrini, R; Lacan, P; Desage, M; Francina, A

    1998-08-01

    The decarboxylation of [1-13C]leucine by hydroxyl radicals was studied by using gas chromatography-isotope ratio mass spectrometry (GC-IRMS) to follow the production of 13CO2. A Fenton reaction between a (Fe2+)-porphyrin and hydrogen peroxide under aerobic conditions yielded hydroxyl radicals. The decarboxylation rates (VLeu) measured by GC-IRMS were dependent on [1-13C]leucine, porphyrin and hydrogen peroxide concentrations. The 13CO2 production was also dependent on bicarbonate or carbon dioxide added in the reaction medium. Bicarbonate facilitated 13CO2 production, whereas carbon dioxide decreased 13CO2 production. Proton effects on some decarboxylation intermediates could explain bicarbonate or carbon dioxide effects. No effect on the decarboxylation rates was observed in the presence of the classical hydroxyl radicals scavengers dimethyl sulfoxide, mannitol, and uric acid. By contrast, a competitive effect with a strong decrease of the decarboxylation rates was observed in the presence of various amino acids: unlabeled leucine, valine, phenylalanine, cysteine, lysine, and histidine. Two reaction products, methyl-4 oxo-2 pentanoate and methyl-3 butanoate were identified by gas chromatography-mass spectrometry in comparison with standards. The present results suggest that [1-13C]leucine can participate to the coordination sphere of (Fe2+)-porphyrin, with a caged process of the hydroxyl radicals which cannot get out of the coordination sphere. PMID:9680180

  19. Assignment of 1H and 13C hyperfine-shifted resonances for tuna ferricytochrome c.

    PubMed Central

    Sukits, S F; Satterlee, J D

    1996-01-01

    Tuna ferricytochrome c has been used to demonstrate the potential for completely assigning 1H and 13C strongly hyperfine-shifted resonances in metalloprotein paramagnetic centers. This was done by implementation of standard two-dimensional NMR experiments adapted to take advantage of the enhanced relaxation rates of strongly hyperfine-shifted nuclei. The results show that complete proton assignments of the heme and axial ligands can be achieved, and that assignments of several strongly shifted protons from amino acids located close to the heme can also be made. Virtually all proton-bearing heme 13C resonances have been located, and additional 13C resonances from heme vicinity amino acids are also identified. These results represent an improvement over previous proton resonance assignment efforts that were predicated on the knowledge of specific assignments in the diamagnetic protein and relied on magnetization transfer experiments in heterogeneous solutions composed of mixtures of diamagnetic ferrocytochrome c and paramagnetic ferricytochrome c. Even with that more complicated procedure, complete heme proton assignments for ferricytochrome c have never been demonstrated by a single laboratory. The results presented here were achieved using a more generally applicable strategy with a solution of the uniformly oxidized protein, thereby eliminating the requirement of fast electron self-exchange, which is a condition that is frequently not met. PMID:8913622

  20. Alteration of interaction between astrocytes and neurons in different stages of diabetes: a nuclear magnetic resonance study using [1-(13)C]glucose and [2-(13)C]acetate.

    PubMed

    Wang, Na; Zhao, Liang-Cai; Zheng, Yong-Quan; Dong, Min-Jian; Su, Yongchao; Chen, Wei-Jian; Hu, Zi-Long; Yang, Yun-Jun; Gao, Hong-Chang

    2015-01-01

    Increasing evidence has shown that the brain is a site of diabetic end-organ damage. This study investigates cerebral metabolism and the interactions between astrocytes and neurons at different stages of diabetes to identify the potential pathogenesis of diabetic encephalopathy. [1-(13)C]glucose or [2-(13)C]acetate is infused into 1- and 15-week diabetic rats, the brain extracts of which are analyzed by using (1)H and (13)C magnetic resonance spectroscopy. The (13)C-labeling pattern and enrichment of cerebral metabolites are also investigated. The increased (13)C incorporation in the glutamine, glutamate, and γ-aminobutyric acid carbons from [2-(13)C]acetate suggests that the astrocytic mitochondrial metabolism is enhanced in 1-week diabetic rats. By contrast, the decreased labeling from [1-(13)C]glucose reflected that the neuronal mitochondrial metabolism is impaired. As diabetes developed to 15 weeks, glutamine and glutamate concentrations significantly decreased. The increased labeling of glutamine C4 but unchanged labeling of glutamate C4 from [2-(13)C]acetate suggests decreased astrocyte supply to the neurons. In addition, the enhanced pyruvate recycling pathway manifested by the increased lactate C2 enrichment in 1-week diabetic rats is weakened in 15-week diabetic rats. Our study demonstrates the overall metabolism disturbances, changes in specific metabolic pathways, and interaction between astrocytes and neurons during the onset and development of diabetes. These results contribute to the mechanistic understanding of diabetes pathogenesis and evolution. PMID:25048983

  1. Analysis of Hydroperoxides in Solid Polyethylene by MAS (13)C NMR and EPR

    SciTech Connect

    ASSINK,ROGER A.; CELINA,MATHIAS C.; DUNBAR,TIMOTHY D.; ALAM,TODD M.; CLOUGH,ROGER LEE; GILLEN,KENNETH T.

    1999-11-19

    {sup 13}C-enriched polyethylene was subjected to {gamma}-irradiation in the presence of air at 25 and 80 C for total doses ranging from 71 to 355 kGy. Significant quantities of hydroperoxides were detected in the 25 C irradiated sample by {sup 13}C magic angle spinning NMR spectroscopy. This method of detection was performed on the solid polymer and required no chemical derivatization or addition of solvent. The chemical stability and subsequent products of the hydroperoxide species were studied by annealing the irradiated samples in air at temperatures ranging from 22 to 110 C. A time-temperature superposition analysis provided an activation energy of 108 kJ/mol for the hydroperoxide decomposition process. The primary products of hydroperoxide decomposition were ketones and secondary alcohols with lesser amounts of acids and esters. EPR measurements suggest that the reactive hydroperoxide species reside in the amorphous phase of polyethylene, consistent with degradation occurring in the amorphous phase.

  2. Relaxation-Compensated Difference Spin Diffusion NMR for Detecting 13C-13C Long-Range Correlations in Proteins and Polysaccharides

    PubMed Central

    Wang, Tuo; Williams, Jonathan K.; Schmidt-Rohr, Klaus; Hong, Mei

    2015-01-01

    The measurement of long-range distances remains a challenge in solid-state NMR structure determination of biological macromolecules. In 2D and 3D correlation spectra of uniformly 13C-labeled biomolecules, inter-residue, inter-segmental, and intermolecular 13C-13C cross peaks that provide important long-range distance constraints for three-dimensional structures often overlap with short-range cross peaks that only reflect the covalent structure of the molecule. It is therefore desirable to develop new approaches to obtain spectra containing only long-range cross peaks. Here we show that a relaxation-compensated modification of the commonly used 2D 1H-driven spin diffusion (PDSD) experiment allows the clean detection of such long-range cross peaks. By adding a z-filter to keep the total z-period of the experiment constant, we compensate for 13C T1 relaxation. As a result, the difference spectrum between a long- and a scaled short-mixing time spectrum show only long-range correlation signals. We show that one- and two-bond cross peaks equalize within a few tens of milliseconds. Within ~200 ms, the intensity equilibrates within an amino acid residue and a monosaccharide to a value that reflects the number of spins in the local network. With T1 relaxation compensation, at longer mixing times, inter-residue and inter-segmental cross peaks increase in intensity whereas intra-segmental cross-peak intensities remain unchanged relative to each other and can all be subtracted out. Without relaxation compensation, the difference 2D spectra exhibit both negative and positive intensities due to heterogeneous T1 relaxation in most biomolecules, which can cause peak cancellation. We demonstrate this relaxation-compensated difference PDSD approach on amino acids, monosaccharides, a crystalline model peptide, a membrane-bound peptide and a plant cell wall sample. The resulting difference spectra yield clean multi-bond, inter-residue and intermolecular correlation peaks, which are

  3. Single voxel localization for dynamic hyperpolarized 13C MR spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Albert P.; Cunningham, Charles H.

    2015-09-01

    The PRESS technique has been widely used to achieve voxel localization for in vivo1H MRS acquisitions. However, for dynamic hyperpolarized 13C MRS experiments, the transition bands of the refocusing pulses may saturate the pre-polarized substrate spins flowing into the voxel. This limitation may be overcome by designing refocusing pulses that do not perturb the resonance of the hyperpolarized substrate, but selectively refocuses the spins of the metabolic products. In this study, a PRESS pulse sequence incorporating spectral-spatial refocusing pulses that have a stop band ('notch') at the substrate resonance is tested in vivo using hyperpolarized [1-13C]pyruvate. Higher metabolite SNR was observed in experiments using the spectral-spatial refocusing pulses as compared to conventional refocusing pulses.

  4. Single voxel localization for dynamic hyperpolarized (13)C MR spectroscopy.

    PubMed

    Chen, Albert P; Cunningham, Charles H

    2015-09-01

    The PRESS technique has been widely used to achieve voxel localization for in vivo(1)H MRS acquisitions. However, for dynamic hyperpolarized (13)C MRS experiments, the transition bands of the refocusing pulses may saturate the pre-polarized substrate spins flowing into the voxel. This limitation may be overcome by designing refocusing pulses that do not perturb the resonance of the hyperpolarized substrate, but selectively refocuses the spins of the metabolic products. In this study, a PRESS pulse sequence incorporating spectral-spatial refocusing pulses that have a stop band ('notch') at the substrate resonance is tested in vivo using hyperpolarized [1-(13)C]pyruvate. Higher metabolite SNR was observed in experiments using the spectral-spatial refocusing pulses as compared to conventional refocusing pulses. PMID:26232365

  5. 13C-NMR study of acetate assimilation in Thermoproteus neutrophilus.

    PubMed

    Schäfer, S; Paalme, T; Vilu, R; Fuchs, G

    1989-12-22

    Acetate assimilation into amino acids and the functioning of central biosynthetic pathways in the extremely thermophilic anaerobic archaebacterium Thermoproteus neutrophilus was investigated using 13C NMR as the method for determination of the labelling patterns. Acetate was assimilated via reductive carboxylation of acetyl-CoA to pyruvate and pyruvate conversion to phosphoenolpyruvate which was further carboxylated to oxaloacetate. 2-Oxoglutarate was mainly formed via citrate. However, the labelling patterns of glutamic acid and alanine were in agreement with the concurrent synthesis of about 15% 2-oxoglutarate and 5% pyruvate through the reductive citric acid cycle. A scrambling phenomenon occurring in aspartate and all amino acids derived through oxaloacetate was observed. The labelling patterns of amino acids were in agreement with their standard biosynthetic pathways, with two remarkable exceptions: isoleucine was synthesized via the citramalate pathway and lysine was synthesized via the 2-aminoadipate pathway which has previously been reported only in eukaryotic microorganisms. PMID:2514097

  6. Interlobe communication in 13C-methionine-labeled human transferrin.

    PubMed

    Beatty, E J; Cox, M C; Frenkiel, T A; Tam, B M; Mason, A B; MacGillivray, R T; Sadler, P J; Woodworth, R C

    1996-06-18

    [1H, 13C] NMR investigations of metal-induced conformational changes in the blood serum protein transferrin (80 kDa) are reported. These are thought to play an important role in the recognition of this protein by its cellular receptors. [1H, 13C] NMR resonance assignments are presented for all nine methionine 13CH3 groups of recombinant deglycosylated human transferrin on the basis of studies of recombinant N-lobe (40 kDa, five Met residues), NOESY-relayed [1H, 13C] HMQC spectra, and structural considerations. The first specific assignments for C-lobe resonances of transferrin are presented. Using methionine 13CH3 resonances as probes, it is shown that, with oxalate as the synergistic anion, Ga3+ binds preferentially to the C-lobe and subsequently to the N-lobe. The NMR shifts of Met464, which is in the Trp460-centered hydrophobic patch of helix 5 in the C-lobe in contact with the anion and metal binding site, show that Ga3+ binding causes movement of side chains within this helix, as is also the case in the N-lobe. The C-lobe residue Met382, which contacts the N-lobe hinge region, is perturbed when Ga3+ binds to the N-lobe, indicative of interlobe communication, a feature which may control the recognition of fully-metallated transferrin by its receptor. These results demonstrate that selective 13C labeling is a powerful method for probing the structure and dynamics of high-molecular-mass proteins. PMID:8672464

  7. (13)C-metabolic flux analysis of lipid accumulation in the oleaginous fungus Mucor circinelloides.

    PubMed

    Zhao, Lina; Zhang, Huaiyuan; Wang, Liping; Chen, Haiqin; Chen, Yong Q; Chen, Wei; Song, Yuanda

    2015-12-01

    The oleaginous fungus Mucor circinelloides is of industrial interest because it can produce high levels of polyunsaturated fatty acid γ-linolenic acid. M. circinelloides CBS 277.49 is able to accumulate less than 15% of cell dry weight as lipids, while M. circinelloides WJ11 can accumulate lipid up to 36%. In order to better understand the mechanisms behind the differential lipid accumulation in these two strains, tracer experiments with (13)C-glucose were performed with the growth of M. circinelloides and subsequent gas chromatography-mass spectrometric detection of (13)C-patterns in proteinogenic amino acids was carried out to identify the metabolic network topology and estimate intracellular fluxes. Our results showed that the high oleaginous strain WJ11 had higher flux of pentose phosphate pathway and malic enzyme, lower flux in tricarboxylic acid cycle, higher flux in glyoxylate cycle and ATP: citrate lyase, together, it might provide more NADPH and substrate acetyl-CoA for fatty acid synthesis. PMID:26318243

  8. Direct uptake of organically derived carbon by grass roots and allocation in leaves and phytoliths: 13C labeling evidence

    NASA Astrophysics Data System (ADS)

    Alexandre, Anne; Balesdent, Jérôme; Cazevieille, Patrick; Chevassus-Rosset, Claire; Signoret, Patrick; Mazur, Jean-Charles; Harutyunyan, Araks; Doelsch, Emmanuel; Basile-Doelsch, Isabelle; Miche, Hélène; Santos, Guaciara M.

    2016-03-01

    In the rhizosphere, the uptake of low-molecular-weight carbon (C) and nitrogen (N) by plant roots has been well documented. While organic N uptake relative to total uptake is important, organic C uptake is supposed to be low relative to the plant's C budget. Recently, radiocarbon analyses demonstrated that a fraction of C from the soil was occluded in amorphous silica micrometric particles that precipitate in plant cells (phytoliths). Here, we investigated whether and to what extent organically derived C absorbed by grass roots can feed the C occluded in phytoliths. For this purpose we added 13C- and 15N-labeled amino acids (AAs) to the silicon-rich hydroponic solution of the grass Festuca arundinacea. The experiment was designed to prevent C leakage from the labeled nutritive solution to the chamber atmosphere. After 14 days of growth, the 13C and 15N enrichments (13C excess and 15N excess) in the roots, stems and leaves as well as phytoliths were measured relative to a control experiment in which no labeled AAs were added. Additionally, the 13C excess was measured at the molecular level, in AAs extracted from roots and stems and leaves. The net uptake of labeled AA-derived 13C reached 4.5 % of the total AA 13C supply. The amount of AA-derived 13C fixed in the plant was minor but not nil (0.28 and 0.10 % of total C in roots and stems/leaves, respectively). Phenylalanine and methionine that were supplied in high amounts to the nutritive solution were more 13C-enriched than other AAs in the plant. This strongly suggested that part of AA-derived 13C was absorbed and translocated into the plant in its original AA form. In phytoliths, AA-derived 13C was detected. Its concentration was on the same order of magnitude as in bulk stems and leaves (0.15 % of the phytolith C). This finding strengthens the body of evidences showing that part of organic compounds occluded in phytoliths can be fed by C entering the plant through the roots. Although this experiment was done in

  9. 13c Measurements On Air of Small Ice Samples

    NASA Astrophysics Data System (ADS)

    Eyer, M.; Leuenberger, M.

    We have developed a new method for 13C analysis for very small air amounts of less than 0.5 cc STP, corresponding to less than 10 gram of ice. It is based on the needle-crasher technique, which we routinely use for CO2 concentration measurements by infrared laser absorption. The extracted air is slowly expanded into a large volume through a water trap held at ­100°C. This sampled air is then carried by a high helium flux through a modified Precon system of Thermo-Finnigan to separate CO2 from the air and to inject the pure CO2 gas in a low helium stream via an open split device to a Delta Plus XL mass spectrometer. The overall precision based on replicates of standard air is significantly better than 0.1 for a single analysis and is further improved by a triplicate measurement of the same sample through a specially designed gas splitter. We have used this new method for investigations on polar ice cores. The 13C measurements are important for climate reconstructions, e.g. to reconstruct the evolution and its variability in the terrestrial and oceanic carbon sinks and to identify natural variations in the marine carbon cycle. During the industrialization atmospheric 13C decreased by about -2, mainly due to the anthropogenic release of biogenic CO2 by fossil fuel burning. Reconstructions of carbon and oxygen cycles of Joos at al. [1999] using a double deconvolution method show that between 1930 and 1950 the net terrestrial release is changing to a net terrestrial uptake of CO2. A highly resolved 13C dataset of this time window would replenish the documentation of this behaviour. Further, it would be interesting to compare such data with O2/N2 measurements, known as an other partitioning tool for carbon sources and sinks. At the EGS 2002 we will present a highly resolved 13C record from Antarctic ice covering this time period.

  10. Millimeter and submillimeter wave spectra of 13C methylamine

    NASA Astrophysics Data System (ADS)

    Motiyenko, R. A.; Margulès, L.; Ilyushin, V. V.; Smirnov, I. A.; Alekseev, E. A.; Halfen, D. T.; Ziurys, L. M.

    2016-03-01

    Context. Methylamine (CH3NH2) is a light molecule of astrophysical interest, which has an intensive rotational spectrum that extends in the submillimeter wave range and far beyond, even at temperatures characteristic for the interstellar medium. It is likely for 13C isotopologue of methylamine to be identified in astronomical surveys, but there is no information available for the 13CH3NH2 millimeter and submillimeter wave spectra. Aims: In this context, to provide reliable predictions of 13CH3NH2 spectrum in millimeter and submillimeter wave ranges, we have studied rotational spectra of the 13C methylamine isotopologue in the frequency range from 48 to 945 GHz. Methods: The spectrum of 13C methylamine was recorded using conventional absorption spectrometers. The analysis of the rotational spectrum of 13C methylamine in the ground vibrational state was performed on the basis of the group-theoretical high-barrier tunneling Hamiltonian that was developed for methylamine. The available multiple observations of the parent methylamine species toward Sgr B2(N) at 1, 2, and 3 mm using the Submillimeter Telescope and the 12 m antenna of the Arizona Radio Observatory were used to make a search for interstellar 13CH3NH2. Results: In the recorded spectra, we have assigned 2721 rotational transitions that belong to the ground vibrational state of the 13CH3NH2. These measurements were fitted to the Hamiltonian model that uses 75 parameters to achieve an overall weighted rms deviation of 0.73. On the basis of these spectroscopic results, predictions of transition frequencies in the frequency range up to 950 GHz with J ≤ 50 and Ka ≤ 20 are presented. The search for interstellar 13C methylamine in available observational data was not successful and therefore only an upper limit of 6.5 × 1014 cm-2 can be derived for the column density of 13CH3NH2 toward Sgr B2(N), assuming the same source size, temperature, linewidth, and systemic velocity as for parent methylamine isotopic

  11. Synthesis and applications of selectively {sup 13}C-labeled RNA

    SciTech Connect

    SantaLucia, J. Jr.; Shen, L.X.; Lewis, H.; Cai, Z.; Tinoci, I. Jr.

    1994-12-01

    Spectral overlap is a substantial problem in NMR studies of RNA molecules >30 nucleotides. To overcome this difficulty, we synthesized selectively {sup 13}C-labeled RNAs and adapted several isotope-edited two- and three-dimensional NMR experiments originally developed for protein studies. We optimized protocols for synthesis of multi-gram quantities of CTP, UTp, ATP, and GTP using a combination of synthetic organic and enzymatic methods. Uracil is prepared in 40 to 50% yield from {sup 13}C-cyanide in two steps. Using acetyl- tribenzoyl-ribose and standard chemistry uracil is then attached to the sugar (90% yield). The tribenzoyl-uridine intermediate is converted into uridine or cytidine quantitatively, depending on the deblocking protocol. Labeled purines are synthesized using simple pyrimidine precursors and reacting with {sup 13}C-formic acid (80% yield). Purine nucleosides are then synthesized using uridine phosphorylase and purine nucleoside phosphorylase. The nucleosides were converted to NMPs by treatment with POC1{sub 3} in triethylphosphate. We converted NMPs to NTPs by standard enzymatic methods. Selectively labeled RNAs were synthesized by run-off transcription using {sup 13}C-labeled NTPs. Several different strategies help solve over-lap problems in larger RNAs. Isotope-edited two-dimensional NMR experiments such as {omega}1-1/2 X-filtered NOESY simplify NMR spectra by dividing the normal NOESY spectrum into two subspectra-one involving NOEs from protons bound to {sup 12}C and one from protons bound to {sup 13}C. For example, we labeled A and U residues of a 34-nucleotide pseudoknot, and the {sup 12}C subspectrum of the 1/2 X-filtered NOESY contained NOEs only from G and C residues (along with adenine 2H); the {sup 13}C subspectrum contained NOEs only from A and U residues. Each subspectrum has less overlap than the NOESY of an unlabeled sample; the editing strategy allows each resonance to be identified by residue type (A, C, G, or U).

  12. Multi-Spectroscopic Analysis of Seed Quality and 13C-Stable-Iotopologue Monitoring in Initial Growth Metabolism of Jatropha curcas L.

    PubMed Central

    Komatsu, Takanori; Ohishi, Risa; Shino, Amiu; Akashi, Kinya; Kikuchi, Jun

    2014-01-01

    In the present study, we applied nuclear magnetic resonance (NMR), as well as near-infrared (NIR) spectroscopy, to Jatropha curcas to fulfill two objectives: (1) to qualitatively examine the seeds stored at different conditions, and (2) to monitor the metabolism of J. curcas during its initial growth stage under stable-isotope-labeling condition (until 15 days after seeding). NIR spectra could non-invasively distinguish differences in storage conditions. NMR metabolic analysis of water-soluble metabolites identified sucrose and raffinose family oligosaccharides as positive markers and gluconic acid as a negative marker of seed germination. Isotopic labeling patteren of metabolites in germinated seedlings cultured in agar-plate containg 13C-glucose and 15N-nitrate was analyzed by zero-quantum-filtered-total correlation spectroscopy (ZQF-TOCSY) and 13C-detected 1H-13C heteronuclear correlation spectroscopy (HETCOR). 13C-detected HETOCR with 13C-optimized cryogenic probe provided high-resolution 13C-NMR spectra of each metabolite in molecular crowd. The 13C-13C/12C bondmer estimated from 1H-13C HETCOR spectra indicated that glutamine and arginine were the major organic compounds for nitrogen and carbon transfer from roots to leaves. PMID:25401292

  13. /sup 13/C nuclear magnetic resonance studies of the biosynthesis by Microbacterium ammoniaphilum of L-glutamate selectively enriched with carbon-13

    SciTech Connect

    Walker, T.E.; Han, C.H.; Kollman, V.H.; London, R.E.; Matwiyoff, N.A.

    1982-02-10

    /sup 13/C NMR of isotopically enriched metabolites has been used to study the metabolism of Microbacterium ammoniaphilum, a bacterium which excretes large quantities of L-glutamic acid into the medium. Biosynthesis from 90% (1-/sup 13/C) glucose results in relatively high specificity of the label, with (2,4-/sup 13/C/sub 2/) glutamate as the major product. The predominant biosynthetic pathway for synthesis of glutamate from glucose was determined to be the Embden Meyerhof glycolytic pathway followed by P-enolpyruvate carboxylase and the first third of the Krebs cycle. Different metabolic pathways are associated with different correlations in the enrichment of the carbons, reflected in the spectrum as different /sup 13/C-/sup 13/C scalar multiplet intensities. Hence, intensity and /sup 13/C-/sup 13/C multiplet analysis allows quantitation of the pathways involved. Although blockage of the Krebs cycle at the ..cap alpha..-ketoglutarate dehydrogenase step is the basis for the accumulation of glutamate, significant Krebs cycle activity was found in glucose grown cells, and extensive Krebs cycle activity in cells metabolizing (1-/sup 13/C) acetate. In addition to the observation of the expected metabolites, the disaccharide ..cap alpha..,..cap alpha..-trehalose and ..cap alpha..,..beta..-glucosylamine were identified from the /sup 13/C NMR spectra.

  14. 13C metabolic flux analysis at a genome-scale.

    PubMed

    Gopalakrishnan, Saratram; Maranas, Costas D

    2015-11-01

    Metabolic models used in 13C metabolic flux analysis generally include a limited number of reactions primarily from central metabolism. They typically omit degradation pathways, complete cofactor balances, and atom transition contributions for reactions outside central metabolism. This study addresses the impact on prediction fidelity of scaling-up mapping models to a genome-scale. The core mapping model employed in this study accounts for (75 reactions and 65 metabolites) primarily from central metabolism. The genome-scale metabolic mapping model (GSMM) (697 reaction and 595 metabolites) is constructed using as a basis the iAF1260 model upon eliminating reactions guaranteed not to carry flux based on growth and fermentation data for a minimal glucose growth medium. Labeling data for 17 amino acid fragments obtained from cells fed with glucose labeled at the second carbon was used to obtain fluxes and ranges. Metabolic fluxes and confidence intervals are estimated, for both core and genome-scale mapping models, by minimizing the sum of square of differences between predicted and experimentally measured labeling patterns using the EMU decomposition algorithm. Overall, we find that both topology and estimated values of the metabolic fluxes remain largely consistent between core and GSM model. Stepping up to a genome-scale mapping model leads to wider flux inference ranges for 20 key reactions present in the core model. The glycolysis flux range doubles due to the possibility of active gluconeogenesis, the TCA flux range expanded by 80% due to the availability of a bypass through arginine consistent with labeling data, and the transhydrogenase reaction flux was essentially unresolved due to the presence of as many as five routes for the inter-conversion of NADPH to NADH afforded by the genome-scale model. By globally accounting for ATP demands in the GSMM model the unused ATP decreased drastically with the lower bound matching the maintenance ATP requirement. A non

  15. /sup 13/C-/sup 13/C spin-spin coupling constants in structural investigations. II. Conformational structure of vinyl ethers

    SciTech Connect

    Krivdin, L.B.; Shcherbakov, V.V.; Bzhezovskii, V.M.; Kalabin, G.A.

    1986-10-10

    The /sup 13/C-/sup 13/C spin-spin coupling constants between the carbon nuclei of the vinyl group were measured for a series of vinyl ethers. It was established that the unshared electron pairs of the oxygen atom can make a substantial stereospecific contribution to the direct /sup 13/C-/sup 13/C constants of the adjacent nuclei. The observed effect was used to establish the conformational structure of the compounds.

  16. In Vivo Natural-Abundance 13C Nuclear Magnetic Resonance Studies of Living Ectomycorrhizal Fungi 1

    PubMed Central

    Martin, Francis; Canet, Daniel; Marchal, Jean-Pierre; Brondeau, Jean

    1984-01-01

    Natural-abundance 13C nuclear magnetic resonance spectroscopy has been used to study intact mycelia of the ectomycorrhizal fungi Cenococcum graniforme (Ascomycetes) and Hebeloma crustuliniforme (Basidiomycetes). A number of sharp resonances are observed in living fungi. These signals primarily arise from fatty acyl chains and carbohydrate nuclei. The spectra are interpreted in terms of relative concentrations of the major fatty acids present in the fungal triglycerides. The small line width of fatty acids (mainly oleic, linoleic, and palmitic acids) resonances and spin-lattice relaxation time are indicative of fast rotational reorientations and are consequently thought to arise from fatty acyl chains in fat droplets. We were able to locate the site of lipids accumulation within mycelia using light microscopy and histological staining. Many lipid droplets were observed in mycelia of both species. These results suggest that fatty acids droplets could be involved in carbon storage and metabolism from ectomycorrhizal fungi. PMID:16663561

  17. Dramatic 13C-depletion in the plant methoxyl pool and its global biogeochemical implications

    NASA Astrophysics Data System (ADS)

    Keppler, F.; Kalin, R. M.; Harper, D. B.; McRoberts, C. W.; Hamilton, J. T.

    2004-12-01

    Stable isotope analysis has become a powerful tool for environmental scientists, plant biologists, ecologists and geochemists studying global elemental cycles or past climatic conditions. Thus most plant species have been photosynthetically characterised as Calvin cycle (C3), Slack-Hatch cycle (C4) and Crassulacean acid metabolism (CAM) categories using carbon isotope signatures. Moreover variations in the carbon isotope composition (d13C) of compounds, produced and destroyed in the global carbon cycle, are often used to investigate biogeochemical cycles and global source-sink relationships, as well as the underlying mechanisms. Stable isotope techniques are increasingly applied to the study of atmospheric budgets of volatile organic compounds (VOCs). We report evidence that methoxyl groups in terrestrial plants (in esters and aromatic ethers) have a unique carbon isotope signature exceptionally depleted in 13C. Plant-derived C1 volatile organic compounds (VOCs) are also highly depleted in 13C compared with Cn+1 VOCs. Our observations suggest that the plant methoxyl pool is the predominant source of C1 compounds of plant origin in the biosphere such as methanol, chloromethane, bromomethane, iodomethane, and cyanomethane. Moreover this pool, which comprises approximately 2.5% of carbon in plant biomass and represents an important substrate for methanogenesis, is likely to be a significant source of highly depleted methane entering the atmosphere. The distinct 13C depletion of methoxyl groups in plants which is reflected in isotope signatures of C1 VOCs may provide a helpful tool in constraining complex environmental processes. These isotope anomalies have a tremendous potential to improve our understanding of the global cycles of atmospheric trace gases and the biochemical pathways involved. Furthermore methoxyl groups could act as markers for biological activity in organic matter of terrestrial and extraterrestrial origin.

  18. Galactose oxidation using (13)C in healthy and galactosemic children.

    PubMed

    Resende-Campanholi, D R; Porta, G; Ferrioli, E; Pfrimer, K; Ciampo, L A Del; Junior, J S Camelo

    2015-03-01

    Galactosemia is an inborn error of galactose metabolism that occurs mainly as the outcome of galactose-1-phosphate uridyltransferase (GALT) deficiency. The ability to assess galactose oxidation following administration of a galactose-labeled isotope (1-(13)C-galactose) allows the determination of galactose metabolism in a practical manner. We aimed to assess the level of galactose oxidation in both healthy and galactosemic Brazilian children. Twenty-one healthy children and seven children with galactosemia ranging from 1 to 7 years of age were studied. A breath test was used to quantitate (13)CO2 enrichment in exhaled air before and at 30, 60, and 120 min after the oral administration of 7 mg/kg of an aqueous solution of 1-(13)C-galactose to all children. The molar ratios of (13)CO2 and (12)CO2 were quantified by the mass/charge ratio (m/z) of stable isotopes in each air sample by gas-isotope-ratio mass spectrometry. In sick children, the cumulative percentage of (13)C from labeled galactose (CUMPCD) in the exhaled air ranged from 0.03% at 30 min to 1.67% at 120 min. In contrast, healthy subjects showed a much broader range in CUMPCD, with values from 0.4% at 30 min to 5.58% at 120 min. The study found a significant difference in galactose oxidation between children with and without galactosemia, demonstrating that the breath test is useful in discriminating children with GALT deficiencies. PMID:25608239

  19. Choice of dietary protein of vegetarians and omnivores is reflected in their hair protein 13C and 15N abundance.

    PubMed

    Petzke, Klaus J; Boeing, Heiner; Metges, Cornelia C

    2005-01-01

    Stable isotopic (15N, 13C) composition of tissues depends on isotopic pattern of food sources. We investigated whether the isotopic compositions of human hair protein and amino acids reflect the habitual dietary protein intake. Hair samples were analyzed from 100 omnivores (selected randomly out of the 1987-1988 German nutrition survey VERA), and from 15 ovo-lacto-vegetarians (OLV), and from 6 vegans recruited separately. Hair bulk and amino acid specific isotopic compositions were analyzed by isotope-ratio mass spectrometry (EA/IRMS and GC/C/IRMS, respectively) and the results were correlated with data of the 7 day dietary records. Hair bulk 15N and 13C abundances clearly reflect the particular eating habits. Vegans can be distinguished from OLV and both are significantly distinct from omnivores in both 15N and 13C abundances. 15N and 13C abundances rose with a higher proportion of animal to total protein intake (PAPI). Individual proportions of animal protein consumption (IPAP) were calculated using isotopic abundances and a linear regression model using animal protein consumption data of vegans (PAPI = 0) and omnivores (mean PAPI = 0.639). IPAP values positively correlated with the intake of protein, meat, meat products, and animal protein. Distinct patterns for hair amino acid specific 15N and 13C abundances were measured but with lower resolution between food preference groups compared with bulk values. In conclusion, hair 13C and 15N values both reflected the extent of animal protein consumption. Bulk isotopic abundance of hair can be tested for future use in the validation of dietary assessment methods. PMID:15880664

  20. The 13C nuclear magnetic resonance in graphite intercalation compounds

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Resing, H. A.

    1985-01-01

    The (13)C NMR chemical shifts of graphite intercalation compounds were calculated. For acceptor types, the shifts come mainly from the paramagnetic (Ramsey) intra-atomic terms. They are related to the gross features of the two-dimensional band structures. The calculated anisotropy is about -140 ppm and is independent of the finer details such as charge transfer. For donor types, the carbon 2p pi orbitals are spin-polarized because of mixing with metal conduction electrons, thus there is an additional dipolar contribution which may be correlated with the electronic specific heat. The general agreement with experimental data is satisfactory.

  1. S-Factor of radiative р 13C capture

    NASA Astrophysics Data System (ADS)

    Dubovichenko, S. B.

    2012-06-01

    The possibility of description of experimental data on the astrophysical S-factor of radiative р 13C capture within the framework of the potential cluster model with forbidden states is analyzed at energies in the range 0.03-0.8 MeV. It is demonstrated that the behavior of the astrophysical S-factor can be explained based on the Е1-transition to the bound 3 P 1 state of the 14N nucleus in the р 13С channel from the 3 S 1 wave of р 13С scattering at resonant energy of 0.55 MeV (l.s.).

  2. Absolute partial decay-branch measurements in 13C

    NASA Astrophysics Data System (ADS)

    Wheldon, C.; Ashwood, N. I.; Barr, M.; Curtis, N.; Freer, M.; Kokalova, Tz.; Malcolm, J. D.; Ziman, V. A.; Faestermann, Th.; Wirth, H.-F.; Hertenberger, R.; Lutter, R.

    2012-10-01

    The 9Be(6Li,d)13C* reaction at a beam energy of 42 MeV has been investigated using a large-acceptance silicon-strip detector array and the high-resolution Q3D magnetic spectrograph. The Q3D facilitated the unambiguous determination of the reaction channel via identification of the deuteron ejectile, thereby providing the spectrum of excited states in 13C in the range from 10.7 to 15.0 MeV. The silicon array was used to detect and identify the 13C recoil-breakup products with efficiencies of up to 49%. The results obtained for the absolute partial branching ratios represent the first complete measurements for states in this energy region and allow the extraction of reduced widths. The quantities measured for Γn0/Γtot and Γn1/Γtot are 0.91±0.11 and ≤0.13 (10.753 MeV), 0.51±0.04 and 0.51±0.04 (10.818 MeV), 0.68±0.03 and 0.42±0.02 (10.996 MeV), 0.49±0.08 and 0.71±0.11 (11.848 MeV), and 0.49±0.08 and 0.53±0.08 (12.130 MeV), respectively. For the two observed higher-lying energy levels, Γα0/Γtot and Γn1/Γtot have been measured as 0.54±0.02 and 0.45±0.02 (13.760 MeV) and 0.94±0.03 and 0.13±0.02 (14.582 MeV), respectively. The consequences for the proposed molecular structures in 13C are explored following the extraction of reduced widths.

  3. Design of a sup 13 C (1H) RF probe for monitoring the in vivo metabolism of (1- sup 13 C)glucose in primate brain

    SciTech Connect

    Hammer, B.E.; Sacks, W.; Bigler, R.E.; Hennessy, M.J.; Sacks, S.; Fleischer, A.; Zanzonico, P.B. )

    1990-01-01

    The design of an RF probe suitable for obtaining proton-decoupled {sup 13}C spectra from a subhuman primate brain is described. Two orthogonal saddle coils, one tuned to the resonant frequency of {sup 13}C and the other to the resonant frequency of 1H, were used to monitor the in vivo metabolism of (1-{sup 13}C)glucose in rhesus monkey brain at 2.1 T. Difference spectra showed the appearance of {sup 13}C-enriched glutamate and glutamine 30 to 40 min after a bolus injection of (1-{sup 13}C)glucose.

  4. Stable isotope-enhanced two- and three-dimensional diffusion ordered 13C NMR spectroscopy (SIE-DOSY 13C NMR)

    NASA Astrophysics Data System (ADS)

    Vermillion, Karl; Price, Neil P. J.

    2009-06-01

    The feasibility of obtaining high quality homonuclear or heteronuclear diffusion-ordered 13C NMR data is shown to be greatly improved by using 13C isotopically-enriched samples. Stable isotope-enhanced diffusion ordered (SIE-DOSY) 13C NMR has been applied to 13C-enriched carbohydrates, and has been used to determine diffusion coefficients for pentose and hexose monosaccharides, and a disaccharide and trisaccharide. These 2D spectra were obtained with as little as 8 min of acquisition time. Fully resolved 3D DOSY-HMQC NMR spectra of [U- 13C]xylose, [U- 13C]glucose, and [1- 13C gal]lactose were obtained in 5 h. Sample derivatization with [ carbonyl- 13C]acetate (peracetylation) extends the usefulness of the technique to included non-labeled sugars; the 13C-carbonyl - carbohydrate ring proton 1H- 13C correlations also provide additional structural information, as shown for the 3-D DOSY-HMQC analysis of a mixture of maltotriose and lactose per-[ carbonyl- 13C]acetates.

  5. Utilization of low molecular weight organics by soil microorganisms: combination of 13C-labelling with PLFA analysis

    NASA Astrophysics Data System (ADS)

    Gunina, Anna; Dippold, Michaela; Kuzyakov, Yakov

    2014-05-01

    Microbial metabolisation is the main transformation pathway of low molecular weight organic substances (LMWOS), but detailed knowledge concerning the fate of LMWOS in soils is strongly limited. Considering that various LMWOS classes enter biochemical cycles at different steps, we hypothesise that the percentage of their LMWOS-Carbon (C) used for microbial biomass (MB) production and consequently medium-term stabilisation in soil is different. We traced the three main groups of LMWOS: amino acids, sugars and carboxylic acids, by uniformly labelled 13C-alanine, -glutamate, -glucose, -ribose, -acetate and -palmitate. Incorporation of 13C from these LMWOS into MB (fumigation-extraction method) and into phospholipid fatty acids (PLFAs) (Bligh-Dyer extraction, purification and GC-C-IRMS measurement) was investigated under field conditions 3 d and 10 d after LMWOS application. The activity of microbial utilization of LMWOS for cell membrane construction was estimated by replacement of PLFA-C with 13C. Decomposition of LMWOS-C comprised 20-65% of the total label, whereas incorporation of 13C into MB amounted to 20-50% of initially applied 13C on day three and was reduced to 5-30% on day 10. Incorporation of 13C-labelled LMWOS into MB followed the trend sugars > carboxylic acids > amino acids. Differences in microbial utilisation between LMWOS were observed mainly at day 10. Thus, instead of initial rapid uptake, further metabolism within microbial cells accounts for the individual fate of C from different LMWOS in soils. Incorporation of 13C from each LMWOS into each PLFA occurred, which reflects the ubiquitous ability of all functional microbial groups for LMWOS utilization. The preferential incorporation of palmitate can be attributed to its role as a direct precursor for many fatty acids (FAs) and PLFA formation. Higher incorporation of alanine and glucose compared to glutamate, ribose and acetate reflect the preferential use of glycolysis-derived substances in the FAs

  6. Long-Acting Neuraminidase Inhibitor Laninamivir Octanoate (CS-8958) versus Oseltamivir as Treatment for Children with Influenza Virus Infection▿

    PubMed Central

    Sugaya, Norio; Ohashi, Yasuo

    2010-01-01

    We conducted a double-blind, randomized controlled trial to compare a long-acting neuraminidase inhibitor, laninamivir octanoate, with oseltamivir. Eligible patients were children 9 years of age and under who had febrile influenza symptoms of no more than 36-h duration. Patients were randomized to 1 of 3 treatment groups: a group given 40 mg laninamivir (40-mg group), a group given 20 mg laninamivir (20-mg group), and an oseltamivir group. Laninamivir octanoate was administered as a single inhalation. Oseltamivir (2 mg/kg of body weight) was administered orally twice daily for 5 days. The primary end point was the time to alleviation of influenza illness. The primary analysis included 184 patients (61, 61, and 62 in the 40-mg group, 20-mg group, and oseltamivir group, respectively). Laninamivir octanoate markedly reduced the median time to illness alleviation in comparison with oseltamivir in patients infected with oseltamivir-resistant influenza A (H1N1) virus, and the reductions were 60.9 h for the 40-mg group and 66.2 h for the 20-mg group. On the other hand, there were no significant differences in the times to alleviation of illness between the laninamivir groups and oseltamivir group for patients with influenza A (H3N2) or B virus infection. Laninamivir octanoate was well tolerated. The most common adverse events were gastrointestinal events. Laninamivir octanoate was an effective and well-tolerated treatment for children with oseltamivir-resistant influenza A (H1N1) virus infection. Further study will be needed to confirm clinical efficacy against influenza A (H3N2) or B virus infection. Its ease of administration is noteworthy, because a single inhalation is required during the course of illness. PMID:20368393

  7. Time-course metabolic changes in high-fat diet-induced obesity rats: A pilot study using hyperpolarized (13)C dynamic MRS.

    PubMed

    Kim, Gwang-Won; Ahn, Kyu-Youn; Kim, Yun-Hyeon; Jeong, Gwang-Woo

    2016-10-01

    The purpose of this study was to investigate the time-course metabolic changes based on hyperpolarized (13)C magnetic resonance spectroscopy (MRS) in high-fat diet (HFD)-induced obesity rats and the correlation between metabolic and serum enzyme levels. Sprague-Dawley rats were fed either HFD (60% fat) or normal diet (10% fat) for 6weeks. A HyperSense DNP was used to hyperpolarize [1-(13)C] pyruvic acid and the hyperpolarized (13)C MRS was examined every 2weeks in the course of 6weeks using a 3T GE MR750 scanner. The body weight of HFD-induced obese rats was significantly increased compared to normal rats at the 6th week after the onset of feeding (p=0.05). Simultaneously, the HFD-induced obese rats showed significantly increased levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and low-density lipoprotein (LDL)-cholesterol compared to normal rats (p≤0.05). In the dynamic (13)C MR spectra acquired at the 6th week, the obese rats showed significantly increased ratios of [1-(13)C] lactate/[1-(13)C] pyruvate and [1-(13)C] alanine/[1-(13)C] pyruvate (p=0.05). The (13)C spectral outcomes are positively correlated with the enzyme levels of ALT and LDH in the HFD-induced obesity. The [1-(13)C] lactate and [1-(13)C] alanine are potentially considered as noninvasive biomarkers for the HFD-induced obesity. PMID:27374624

  8. In vivo and in vitro liver cancer metabolism observed with hyperpolarized [5-13C]glutamine

    NASA Astrophysics Data System (ADS)

    Cabella, C.; Karlsson, M.; Canapè, C.; Catanzaro, G.; Colombo Serra, S.; Miragoli, L.; Poggi, L.; Uggeri, F.; Venturi, L.; Jensen, P. R.; Lerche, M. H.; Tedoldi, F.

    2013-07-01

    Glutamine metabolism is, with its many links to oncogene expression, considered a crucial step in cancer metabolism and it is thereby a key target for alteration in cancer development. In particular, strong correlations have been reported between oncogene expression and expression and activity of the enzyme glutaminase. This mitochondrial enzyme, which is responsible for the deamidation of glutamine to form glutamate, is overexpressed in many tumour tissues. In animal models, glutaminase expression is correlated with tumour growth rate and it is readily possible to limit tumour growth by suppression of glutaminase activity. In principle, hyperpolarized 13C MR spectroscopy can provide insight to glutamine metabolism and should hence be a valuable tool to study changes in glutaminase activity as tumours progress. However, no such successful in vivo studies have been reported, even though several good biological models have been tested. This may, at least partly, be due to problems in preparing glutamine for hyperpolarization. This paper reports a new and improved preparation of hyperpolarized [5-13C]glutamine, which provides a highly sensitive 13C MR marker. With this preparation of hyperpolarized [5-13C]glutamine, glutaminase activity in vivo in a rat liver tumour was investigated. Moreover, this marker was also used to measure response to drug treatment in vitro in cancer cells. These examples of [5-13C]glutamine used in tumour models warrant the new preparation to allow metabolic studies with this conditionally essential amino acid.

  9. Use of Isotope Ratio Determination (13C/12C) to Assess the Production Method of Sparkling Wine.

    PubMed

    Rossier, Joël S; Maury, Valérie; Gaillard, Laetitia; Pfammatter, Elmar

    2016-01-01

    The production of a sparkling wine can be performed with different methods taking from a few weeks to several years, which often justifies a difference in added value for the consumer. This paper presents the use of isotope ratio δ(13)C measurements combined with physico-chemical analyses for the determination of mislabelling of sparkling wines produced by 'ancestral', 'traditional', 'closed tank' or 'gasification' methods. This work shows that the isotope composition of CO(2) compared with that of the corresponding dried residue of wine (DRW) can assess whether carbonate CO(2) in a sparkling wine originates from alcohol fermentation or from artificial gas addition. Isotopic ratios expressed as δ(13)C(CO2) and δ(13)C(DRW) measurements have been obtained for each wine by gasbench isotopic ratio mass spectroscopy and cavity ring down infrared spectroscopy, respectively. When the difference between δ(13)C(CO2) and δ(13)C(DRW) is negative, the presence of artificial CO(2) can be undoubtedly inferred, which would exclude the production methods 'ancestral' or 'traditional' for instance. Other parameters such as alcohol content, sugar and acid distributions are also important to complete the analytical panel to aid fraud tracking. PMID:27198811

  10. 13C Nuclear Magnetic Resonance Study of Acetate Incorporation into Malate During Ca2+-Uptake by Isolated Leaf Tissues 1

    PubMed Central

    Borchert, Rolf; Everett, Grover W.

    1987-01-01

    13C Nuclear magnetic resonance spectroscopy of leaflets of Gleditsia triacanthos and Albizia julibrisin was used to determine the fate of acetate taken up during the absorption of calcium from 13C-labeled Ca-acetate solution. Small amounts of acetate accumulated temporarily in the leaf tissues, but the bulk of acetate was incorporated into malate. The initial rate of malate synthesis was very low, but increased rapidly during acetate treatment and reached its maximum after 8 hours; the enzymes involved in malate synthesis thus appear to be substrate induced. Use of acetate-2-13C yielded malate labeled in C-3, indicating that vacuolar malate accumulating during Ca-uptake might be synthesized via malate synthase from acetate and glyoxalate. However, a source of glyoxalate condensing with acetate during malate synthesis could not be identified. Glycolate produced in photorespiration is an unlikely source, because glycolate-2-13C was absorbed and metabolized by the leaf tissues into products of the glycolate pathway, but was not a major precursor in malate synthesis. Malate synthesis via the glyoxalate cycle is also unlikely, because no evidence for the recycling of a 13C-labeled 4-carbon organic acid was found. Malate synthesis in the leaflets of Gleditsia and Albizia thus appears to involve the inducible condensation of acetate with a 2-carbon compound of unidentified nature and origin. PMID:16665548

  11. Dynamic 13C NMR analysis of pyruvate and lactate oxidation in the in vivo canine myocardium: evidence of reduced utilization with increased work.

    PubMed

    Rath, D P; Zhu, H; Tong, X; Jiang, Z; Hamlin, R L; Robitaille, P M

    1997-12-01

    In this work, substrate selection was monitored in the left ventricle of the canine myocardium by following pyruvate and lactate oxidation under in vivo conditions at basal and elevated workloads. These studies were conducted in the open chest model using dynamic 13C NMR techniques in the presence and absence of dichloroacetic acid (DCA), a well-known activator of pyruvate dehydrogenase (PDH). Following the infusion of (3-(13)C) pyruvate or (3-(13)C) lactate into the left anterior descending artery, highly variable 13C enrichments of glutamate, alanine, aspartate, and citrate were noted under low (RPP < 14,500 mmHg/min), intermediate (RPP = 15,000-25,000 mmHg/min), and high (RPP > 25,500 mmHg/min) rate pressure products (RPP). At low workloads, the myocardium typically oxidized the infused (3-(13)C) pyruvate or (3-(13)C) lactate and incorporated the labeled carbon into the glutamate pool as expected. However, in a few notable instances (n = 3), 13C-enriched pyruvate and lactate were unable to label the glutamate pool under in vivo conditions even at the lowest RPPs, indicating a lack of selection for these substrates by the tricarboxylic acid (TCA) cycle. Nonetheless, the levels of glutamate C4 enrichment observed at low workloads could usually be enhanced by infusion of DCA. Importantly, 13C NMR extract analysis revealed that (3-(13)C) pyruvate or (3-(13)C) lactate labeling of the glutamate pool was reduced (< 20%) at high workloads in spite of increased DCA concentrations. PMID:9402190

  12. The guest ordering and dynamics in urea inclusion compounds studied by solid-state 1H and 13C MAS NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Yang, Xiaorong; Müller, Klaus

    2011-12-01

    Urea inclusion compounds with different guest species were studied by 13C CP MAS and 1H MAS NMR spectroscopy. It is possible to arrange the asymmetric guest species in three different ways: head-head, head-tail and tail-tail. 13C CP MAS NMR studies indicate that the preference arrangement is determined by the interaction strength of the end functional groups. 13C relaxation experiments are used to study the dynamic properties of urea inclusion compounds. 13C relaxation studies on urea inclusion compounds with n-alkane or decanoic acid show that the 13C T1 and 13C T1ρ values exhibit the position dependence towards the center of the chain, indicating internal chain mobility. The analysis of variable-temperature 13C T1ρ experiments on urea inclusion compounds with hexadecane and pentadecane, for the first time, suggests that chain fluctuations and lateral motion of n-alkane guests may contribute to the 13C T1ρ relaxation.

  13. Synthesis of [3,4-(13)c(2)]-enriched bile salts as NMR probes of protein-ligand interactions.

    PubMed

    Tochtrop, Gregory P; DeKoster, Gregory T; Cistola, David P; Covey, Douglas F

    2002-09-20

    Synthetic methodology that allows for incorporation of isotopic carbon at the C-3 and C-4 positions of bile salts is reported. Three [3,4-(13)C(2)]-enriched bile salts were synthesized from either deoxycholic or lithocholic acid. The steroid 3alpha-OH group was oxidized and the A-ring was converted into the Delta(4)-3-ketone. The C-24 carboxylic acid was next converted into the carbonate group and selectively reduced to the alcohol in the presence of the A-ring enone. Following protection of the 24-OH group, the Delta(4)-3-ketone was converted into the A-ring enol lactone. Condensation of the enol lactone with [1,2-(13)C(2)]-enriched acetyl chloride and subsequent Robinson annulation afforded a [3,4-(13)C(2)]-enriched Delta(4)-3-ketone that was subsequently converted back into a 3alpha-hydroxy-5beta-reduced bile steroid. C-7 hydroxylation, when necessary, was achieved via conversion of the Delta(4)-3-ketone into the corresponding Delta(4,6)-dien-3-one, epoxidation of the Delta(6)-double bond, and hydrogenolysis/hydrogenation of the 5,6-epoxy enone system. The [3,4-(13)C(2)]-enriched bile salts were subsequently complexed to human ileal bile acid binding protein (I-BABP), and (1)H-(13)C HSQC spectra were recorded to show the utility of the compounds for investigating the interactions of bile acids with I-BABP. PMID:12227809

  14. The 4051 Å Comet Band of 13C3

    NASA Astrophysics Data System (ADS)

    Haddad, M. A.; Zhao, D.; Linnartz, H.; Ubachs, W.

    2014-02-01

    The tricarbon C3 molecule has been detected in a number of translucent interstellar clouds via its $A^1\\Piu-X^1\\Sigmag+$ (000-000) electronic `comet' band around 4051 Å. So far, it is the largest molecule unambiguously identified in the diffuse interstellar medium. In this work, rotationally resolved laboratory spectra are presented for the corresponding transition of the 13C3 isotopologue. The spectra are recorded in direct absorption using cavity ring-down spectroscopy in combination with a supersonic plasma jet. A rotational analysis yields accurate spectroscopic parameters. In contrast to 12C3, no significant perturbations are found for (e- or f-parity) levels up to J' = 18 in the A 1Π upper electronic state.

  15. Σ production from targets of ^4He and ^13C

    NASA Astrophysics Data System (ADS)

    Chrien, R. E.

    1996-10-01

    One of the abiding issues in hypernuclear research has been the question of the formation of nuclear bound states incorporating the Σ-hyperon. The recent increases in beam intensity at the Brookhaven AGS have enabled us to obtain a high statistics study on the production of Σ-hyperons on a ^4He target. Earlier research using stopped kaons at KEK indicated the presence of structure in the (K^-,π^-) reaction, and led to the postulate of a Σ bound state. That structure has now been definitely confirmed in the in-flight kaon experiment at the LESB2 beam line and Moby-Dick spectrometer. An improved measurement of the binding energy of the presumed state will be reported, together with a production cross section. In addition, both (K^-,π^-) and (K^-,π^+) reactions on ^13C have been studied and will be compared to similar measurements on ^9Be.

  16. Multiscale computational modeling of (13)C DNP in liquids.

    PubMed

    Küçük, Sami Emre; Sezer, Deniz

    2016-04-14

    Dynamic nuclear polarization (DNP) enables the substantial enhancement of the NMR signal intensity in liquids. While proton DNP is dominated by the dipolar interaction between the electron and nuclear spins, the Fermi contact (scalar) interaction is equally important for heavier nuclei. The impossibility to predict the magnitude and field dependence of the scalar contribution hampers the application of high-field DNP to nuclei other than (1)H. We demonstrate that molecular dynamics (MD) simulations followed by density functional calculations of the Fermi contacts along the MD trajectory lead to quantitative agreement with the DNP coupling factors of the methyl and carbonyl carbons of acetone in water at 0.35 T. Thus, the accurate calculation of scalar-dominated DNP enhancement at a desired magnetic field is demonstrated for the first time. For liquid chloroform at fields above 9 T, our methodology predicts direct (13)C DNP enhancements that are two orders of magnitude larger than those of (1)H. PMID:27001446

  17. Millimeter and submillimeter wave spectra of 13C-glycolaldehydes

    NASA Astrophysics Data System (ADS)

    Haykal, I.; Motiyenko, R. A.; Margulès, L.; Huet, T. R.

    2013-01-01

    Context. Glycolaldehyde (CH2OHCHO) is the simplest sugar and an important intermediate in the path toward forming more complex biologically relevant molecules. Astronomical surveys of interstellar molecules, such as those available with the very sensitive ALMA telescope, require preliminary laboratory investigations of the microwave and submillimeter-wave spectra of molecular species including new isotopologs - to identify these in the interstellar media. Aims: To achieve the detection of the 13C isotopologs of glycolaldehyde in the interstellar medium, their rotational spectra in the millimeter and submillimeter-wave regions were studied. Methods: The spectra of 13CH2OHCHO and CH2OH13CHO were recorded in the 150-945 GHz spectral range in the laboratory using a solid-state submillimeter-wave spectrometer in Lille. The observed line frequencies were measured with an accuracy of 30 kHz up to 700 GHz and of 50 kHz above 700 GHz. We analyzed the spectra with a standard Watson Hamiltonian. Results: About 10 000 new lines were identified for each isotopolog. The spectroscopic parameters were determined for the ground- and the three lowest vibrational states up to 945 and 630 GHz. Previous microwave assignments of 13CH2OHCHO were not confirmed. Conclusions: The provided line-lists and sets of molecular parameters meet the needs for a first astrophysical search of 13C-glycolaldehydes. Full Tables 3 and 4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/549/A96

  18. The First in Vivo Observation of 13C- 15N Coupling in Mammalian Brain

    NASA Astrophysics Data System (ADS)

    Kanamori, Keiko; Ross, Brian D.

    2001-12-01

    [5-13C,15N]Glutamine, with 1J(13C-15N) of 16 Hz, was observed in vivo in the brain of spontaneously breathing rats by 13C MRS at 4.7 T. The brain [5-13C]glutamine peak consisted of the doublet from [5-13C,15N]glutamine and the center [5-13C,14N]glutamine peak, resulting in an apparent triplet with a separation of 8 Hz. The time course of formation of brain [5-13C,15N]glutamine was monitored in vivo with a time resolution of 20-35 min. This [5-13C,15N]glutamine was formed by glial uptake of released neurotransmitter [5-13C]glutamate and its reaction with 15NH3 catalyzed by the glia-specific glutamine synthetase. The neurotransmitter glutamate C5 was selectively13C-enriched by intravenous [2,5-13C]glucose infusion to 13C-label whole-brain glutamate C5, followed by [12C]glucose infusion to chase 13C from the small and rapidly turning-over glial glutamate pool, leaving 13C mainly in the neurotransmitter [5-13C]glutamate pool, which is sequestered in vesicles until release. Hence, the observed [5-13C,15N]glutamine arises from a coupling between 13C of neuronal origin and 15N of glial origin. Measurement of the rate of brain [5-13C,15N]glutamine formation provides a novel noninvasive method of studying the kinetics of neurotransmitter uptake into glia in vivo, a process that is crucial for protecting the brain from glutamate excitotoxicity.

  19. Spectrally edited 2D 13Csbnd 13C NMR spectra without diagonal ridge for characterizing 13C-enriched low-temperature carbon materials

    NASA Astrophysics Data System (ADS)

    Johnson, Robert L.; Anderson, Jason M.; Shanks, Brent H.; Fang, Xiaowen; Hong, Mei; Schmidt-Rohr, Klaus

    2013-09-01

    Two robust combinations of spectral editing techniques with 2D 13Csbnd 13C NMR have been developed for characterizing the aromatic components of 13C-enriched low-temperature carbon materials. One method (exchange with protonated and nonprotonated spectral editing, EXPANSE) selects cross peaks of protonated and nearby nonprotonated carbons, while the other technique, dipolar-dephased double-quantum/single-quantum (DQ/SQ) NMR, selects signals of bonded nonprotonated carbons. Both spectra are free of a diagonal ridge, which has many advantages: Cross peaks on the diagonal or of small intensity can be detected, and residual spinning sidebands or truncation artifacts associated with the diagonal ridge are avoided. In the DQ/SQ experiment, dipolar dephasing of the double-quantum coherence removes protonated-carbon signals; this approach also eliminates the need for high-power proton decoupling. The initial magnetization is generated with minimal fluctuation by combining direct polarization, cross polarization, and equilibration by 13C spin diffusion. The dipolar dephased DQ/SQ spectrum shows signals from all linkages between aromatic rings, including a distinctive peak from polycondensed aromatics. In EXPANSE NMR, signals of protonated carbons are selected in the first spectral dimension by short cross polarization combined with dipolar dephasing difference. This removes ambiguities of peak assignment to overlapping signals of nonprotonated and protonated aromatic carbons, e.g. near 125 ppm. Spin diffusion is enhanced by dipolar-assisted rotational resonance. Before detection, Csbnd H dipolar dephasing by gated decoupling is applied, which selects signals of nonprotonated carbons. Thus, only cross peaks due to magnetization originating from protonated C and ending on nearby nonprotonated C are retained. Combined with the chemical shifts deduced from the cross-peak position, this double spectral editing defines the bonding environment of aromatic, COO, and Cdbnd O carbons

  20. 1H to 13C Energy Transfer in Solid State NMR Spectroscopy of Natural Organic Systems

    NASA Astrophysics Data System (ADS)

    Berns, Anne E.; Conte, Pellegrino

    2010-05-01

    . The Hartmann-Hahn condition can be expressed as γHB1H = γCB1C, where γH and γC are the gyromagnetic ratios of protons and carbons, whereas B1H and B1C are the 1H and 13C radio-frequency (r.f.) fields applied to the nuclei. The Hartmann-Hahn condition is affected by the H-C dipolar interaction strength (Stejskal & Memory, 1994). All the factors affecting dipolar interactions may mismatch the Hartmann-Hahn condition and prevent a quantitative representation of the NOM chemical composition (Conte et al., 2004). It has been reported that under low speed MAS conditions, broad matching profiles are centered around the Hartmann-Hahn condition....... With increasing spinning speed the Hartmann-Hahn matching profiles break down in a series of narrow matching bands separated by the rotor frequency (Stejskal & Memory, 1994). In order to account for the instability of the Hartmann-Hahn condition at higher rotor spin rates (>10 kHz), variable amplitude cross-polarization techniques (RAMP-CP) have been developed (Metz et al., 1996). So far, to our knowledge, the prevailing way used to obtain quantitative 13C-CPMAS NMR results was to optimize the 1H and 13C spin lock r.f. fields on simple standard systems such as glycine and to use those r.f. field values to run experiments on unknown organic samples. The aim of the present study was to experimentally evidence that the stability of the Hartmann-Hahn condition was different for different samples with a known structure. Moreover, Hartmann-Hahn profiles of four different humic acids (HAs) were also provided in order to show that the 1H/13C r.f. spin lock field strength must also be tested on the HAs prior to a quantitative evaluation of their 13C-CPMAS NMR spectra. Baldock, J.A., Oades, J.M., Nelson, P.N., Skene, T.M., Golchin, A. & Clarke, P., 1997. Assessing the extent of decomposition of natural organic materials using solid-state C-13 NMR spectroscopy. Australian Journal of Soil Research, 35, 1061-1083. Conte, P., Piccolo, A

  1. Cutting the Gordian Knot: Identifiability of anaplerotic reactions in Corynebacterium glutamicum by means of (13) C-metabolic flux analysis.

    PubMed

    Kappelmann, Jannick; Wiechert, Wolfgang; Noack, Stephan

    2016-03-01

    Corynebacterium glutamicum is the major workhorse for the microbial production of several amino and organic acids. As long as these derive from tricarboxylic acid cycle intermediates, the activity of anaplerotic reactions is pivotal for a high biosynthetic yield. To determine single anaplerotic activities (13) C-Metabolic Flux Analysis ((13) C-MFA) has been extensively used for C. glutamicum, however with different network topologies, inconsistent or poorly determined anaplerotic reaction rates. Therefore, in this study we set out to investigate whether a focused isotopomer model of the anaplerotic node can at all admit a unique solution for all fluxes. By analyzing different scenarios of active anaplerotic reactions, we show in full generality that for C. glutamicum only certain anaplerotic deletion mutants allow to uniquely determine the anaplerotic fluxes from (13) C-isotopomer data. We stress that the result of this analysis for different assumptions on active enzymes is directly transferable to other compartment-free organisms. Our results demonstrate that there exist biologically relevant metabolic network topologies for which the flux distribution cannot be inferred by classical (13) C-MFA. PMID:26375179

  2. 15N and13C NMR investigation of hydroxylamine-derivatized humic substances

    USGS Publications Warehouse

    Thorn, K.A.; Arterburn, J.B.; Mikita, M.A.

    1992-01-01

    Five fulvic and humic acid samples of diverse origins were derivatized with 15N-labeled hydroxylamine and analyzed by liquid-phase 15N NMR spectrometry. The 15N NMR spectra indicated that hydroxylamine reacted similarly with all samples and could discriminate among carbonyl functional groups. Oximes were the major derivatives; resonances attributable to hydroxamic acids, the reaction products of hydroxylamine with esters, and resonances attributable to the tautomeric equilibrium position between the nitrosophenol and monoxime derivatives of quinones, the first direct spectroscopic evidence for quinones, also were evident. The 15N NMR spectra also suggested the presence of nitriles, oxazoles, oxazolines, isocyanides, amides, and lactams, which may all be explained in terms of Beckmann reactions of the initial oxime derivatives. INEPT and ACOUSTIC 15N NMR spectra provided complementary information on the derivatized samples. 13C NMR spectra of derivatized samples indicated that the ketone/quinone functionality is incompletely derivatized with hydroxylamine. ?? 1991 American Chemical Society.

  3. 13C-18O bonding (Δ47) in deep-sea corals: a calibration study

    NASA Astrophysics Data System (ADS)

    Kimball, J. B.; Tripati, A.; Dunbar, R. B.; Eagle, R.

    2013-12-01

    Deep-sea corals are a potentially valuable archive of temperature in intermediate and deep waters, regions for which a paucity of temperature data exists. These archives could give valuable insight into the natural variability of areas of the ocean that play an active role in large-scale climate dynamics. Due to significant 'vital effects' (i.e., non-equilibrium mineral compositions) in δ18O, however, deep-sea coral have been challenging to develop as a paleotemperature proxy. Clumped-isotope paleothermometry is a new method that may circumvent some of the known complications with δ18O paleotemperature analysis in deep-sea coral. This geothermometer is based on the ordering of heavy 13C-18O ';clumps' in carbonate minerals. Initial calibration studies have shown that the method is independent from the solution chemistry of the precipitating fluids as well as 'vital effects' in deep-sea corals and other types of carbonates. Some kinetic effects have been observed in tropical corals and speleothems. Here we report new data in order to further develop clumped isotopes as a paleothermometer in deep-sea corals as well as to investigate taxon-specific effects. 13C-18O bond ordering was analyzed in live-collected scleractinian (Enallopsammia sp.) and gorgonian (Isididae and Coralliidae) deep-sea corals. We determined mass 47 anomalies in samples (Δ47), which refers to the parts per thousand excess of 13C-18O-16O in CO2 produced on acid digestion of a sample, relative to the amount predicted to be present if isotopes were randomly distributed amongst all CO2 isotopologues. Measured Δ47 values were compared to in situ temperatures and the relationship between Δ47 and temperature was determined for each group to investigate taxon-specific effects.

  4. Solvation of sodium octanoate micelles in concentrated urea solution studied by means of molecular dynamics simulations.

    PubMed

    de Moura, André Farias; Bernardino, Kalil; de Oliveira, Osmair Vital; Freitas, Luiz Carlos Gomide

    2011-12-15

    The effects of urea on self-assembling remains a challenging topic on surface chemistry, and computational modeling may have a role on the unraveling of the molecular mechanisms underlying these effects. Bearing that in mind, we performed a set of molecular dynamics simulations to assess the effects of urea on the self-assembling properties of sodium octanoate, an anionic surfactant, as compared to the aggregation of the same surfactant in pure water as the solvent. The concentration of free monomers increased 3-fold in the presence of urea, in agreement with the accepted view that urea should increase monomer solubility. Regarding the size distribution of micellar aggregates, the urea solution favored smaller micelles and a narrower distribution. Preferential solvation by either water or urea changed along the surfactant molecules, from urea-rich shells around apolar atoms at the end of the hydrophobic tails to nearly no urea at the polar headgroups. This solvation profile is consistent with two different hypotheses from the literature: on one hand, urea molecules interact directly with apolar atoms from the hydrophobic tails, acting as a surfactant, and on the other hand the presence of urea molecules increases the hydration of polar sites. Another important observation regards the solvent structure, which exhibits a complex composition profile around both water and urea molecules. Although the solvent structure was appreciably different in each case, the free energy calculations for the dissociation of a pair of octanoate molecules pointed to a purely enthalpic free energy loss in urea solution, a finding that does not lend support to the third hypothesis that is often claimed as accounting for the urea effects, namely, that urea disrupts water structure and that this structural change decreases the hydrophobic effect due to an entropy change. The presence of urea had no significant effect on the molecular structure of the surfactant molecules, although it

  5. Two Categories of 13C/12C Ratios for Higher Plants 1

    PubMed Central

    Smith, Bruce N.; Epstein, Samuel

    1971-01-01

    13C/12C ratios have been determined for plant tissue from 104 species representing 60 families. Higher plants fall into two categories, those with low δPDBI13C values (—24 to —34‰) and those with high δ 13C values (—6 to —19‰). Algae have δ 13C values of —12 to —23‰. Photosynthetic fractionation leading to such values is discussed. PMID:16657626

  6. Accumulation of poly(3-hydroxybutyrate) from octanoate in different pseudomonas belonging to the rRNA homology group I.

    PubMed

    Diard, Stéphane; Carlier, Jean-Philippe; Ageron, Elisabeth; Grimont, Patrick A D; Langlois, Valérie; Guérin, Philippe; Bouvet, Odile M M

    2002-08-01

    It is admitted that one of the characteristics of pseudomonads is their inability to accumulate poly(3-hydroxybutyrate). In this paper, we show that poly(3-hydroxyoctanoate) synthesis is restricted to Pseudomonas rRNA homology group I, which includes both fluorescent and nonfluorescent species. However, within the genus Pseudomonas, the P. aeruginosa complex can be subdivided into two groups: the "P. aeruginosa group", which includes P. aeruginosa, P. alcaligenes, P. citronellolis, P. mendocina, produce poly(3-hydroxyoctanoate) from octanoate and the "P. oleovorans group" which includes the type strain of P. oleovorans, P. pseudoalcaligenes and two Pseudomonas sp., produce poly(3-hydroxybutyrate) during cultivation on octanoate. Strain GPo1 (ATCC 29347) formely identified as P. oleovorans and known to produce various medium-side-chain PHAs such as poly(3-hydroxyoctanoate) has been reclassified in the P. putida complex. PMID:12353870

  7. Inelastic pion scattering by /sup 13/C at low energies

    SciTech Connect

    Mitchell, J.H.

    1987-03-01

    Angular distributions for inelastically scattered pions were obtained for several states in /sup 13/C at an incident energy of 65 MeV. The data include results from both ..pi../sup +/ and ..pi../sup -/ measurements. In addition, ..pi../sup -/ measurements were made at T/sub ..pi../ = 50 MeV at one angle to give a two point fixed-q excitation function. The data are compared to theory and the data of others. As might be expected, medium corrections are shown to be considerably more important at low energies than at resonance. This is true for inelastic transitions of multipolarity 0,2 and 3. Parameters derived from an analysis of elastic pion scattering and SCX data also provide an adequate description of the inelastic transitions. The charge asymmetry in the cross sections for the 9/2/sup +/ state that was seen at resonance persists at these energies. This result is consistent with an impulse approximation treatment of the spin-flip amplitude. This is true even though the incoming energy of the pions is far below the range where the validity of an impulse treatment is expected. 65 refs., 45 figs.

  8. PASADENA hyperpolarization of 13C biomolecules: equipment design and installation

    PubMed Central

    Hövener, Jan-Bernd; Chekmenev, Eduard Y.; Harris, Kent C.; Perman, William H.; Robertson, Larry W.; Bhattacharya, Pratip

    2009-01-01

    Object The PASADENA method has achieved hyperpolarization of 16–20% (exceeding 40,000-fold signal enhancement at 4.7 T), in liquid samples of biological molecules relevant to in vivo MRI and MRS. However, there exists no commercial apparatus to perform this experiment conveniently and reproducibly on the routine basis necessary for translation of PASADENA to questions of biomedical importance. The present paper describes equipment designed for rapid production of six to eight liquid samples per hour with high reproducibility of hyperpolarization. Materials and methods Drawing on an earlier, but unpublished, prototype, we provide diagrams of a delivery circuit, a laminar-flow reaction chamber within a low field NMR contained in a compact, movable housing. Assembly instructions are provided from which a computer driven, semiautomated PASADENA polarizer can be constructed. Results Together with an available parahydrogen generator, the polarizer, which can be operated by a single investigator, completes one cycle of hyperpolarization each 52 s. Evidence of efficacy is presented. In contrast to competing, commercially available devices for dynamic nuclear polarization which characteristically require 90 min per cycle, PASADENA provides a low-cost alternative for high throughput. Conclusions This equipment is suited to investigators who have an established small animal NMR and wish to explore the potential of heteronuclear (13C and 15N) MRI, MRS, which harnesses the enormous sensitivity gain offered by hyperpolarization. PMID:19067008

  9. New optical analyzer for 13C-breath test

    NASA Astrophysics Data System (ADS)

    Harde, Hermann; Dressler, Matthias; Helmrich, Günther; Wolff, Marcus; Groninga, Hinrich

    2008-04-01

    Medical breath tests are well established diagnostic tools, predominantly for gastroenterological inspections, but also for many other examinations. Since the composition and concentration of exhaled volatile gases reflect the physical condition of a patient, a breath analysis allows one to recognize an infectious disease in an organ or even to identify a tumor. One of the most prominent breath tests is the 13C-urea-breath test, applied to ascertain the presence of the bacterium helicobacter pylori in the stomach wall as an indication of a gastric ulcer. In this contribution we present a new optical analyzer that is based on photoacoustic spectroscopy and uses a DFB diode laser at 2.744 μm. The concentration ratio of the CO II isotopologues is determined by measuring the absorption on a 13CO II line in comparison to a 12CO II line. In the specially selected spectral range the lines have similar strengths, although the concentrations differ by a factor of 90. Therefore, the signals are well comparable. Due to an excellent signal-noise-ratio isotope variations of less than 1% can be resolved as required for the breath test.

  10. Pathway analysis using (13) C-glycerol and other carbon tracers reveals a bipartite metabolism of Legionella pneumophila.

    PubMed

    Häuslein, Ina; Manske, Christian; Goebel, Werner; Eisenreich, Wolfgang; Hilbi, Hubert

    2016-04-01

    Amino acids represent the prime carbon and energy source for Legionella pneumophila, a facultative intracellular pathogen, which can cause a life-threatening pneumonia termed Legionnaires' disease. Genome, transcriptome and proteome studies indicate that L. pneumophila also utilizes carbon substrates other than amino acids. We show here that glycerol promotes intracellular replication of L. pneumophila in amoeba or macrophages (but not extracellular growth) dependent on glycerol-3-phosphate dehydrogenase, GlpD. An L. pneumophila mutant strain lacking glpD was outcompeted by wild-type bacteria upon co-infection of amoeba, indicating an important role of glycerol during infection. Isotopologue profiling studies using (13) C-labelled substrates were performed in a novel minimal defined medium, MDM, comprising essential amino acids, proline and phenylalanine. In MDM, L. pneumophila utilized (13) C-labelled glycerol or glucose predominantly for gluconeogenesis and the pentose phosphate pathway, while the amino acid serine was used for energy generation via the citrate cycle. Similar results were obtained for L. pneumophila growing intracellularly in amoeba fed with (13) C-labelled glycerol, glucose or serine. Collectively, these results reveal a bipartite metabolism of L. pneumophila, where glycerol and carbohydrates like glucose are mainly fed into anabolic processes, while serine serves as major energy supply. PMID:26691313

  11. In Vivo13C Magnetic Resonance Spectroscopy of Human Brain on a Clinical 3 Tesla Scanner Using [2-13C]Glucose Infusion and Low Power Stochastic Decoupling

    PubMed Central

    Li, Shizhe; Zhang, Yan; Wang, Shumin; Yang, Jehoon; Araneta, Maria Ferraris; Farris, Amanda; Johnson, Christopher; Fox, Stephen; Innis, Robert; Shen, Jun

    2009-01-01

    This study presents the detection of [2-13C]glucose metabolism in the carboxylic/amide region in the human brain, and demonstrates that the cerebral metabolism of [2-13C]glucose can be studied in human subjects in the presence of severe hardware constraints of widely available 3 T clinical scanners and with low power stochastic decoupling. In the carboxylic/amide region of human brain, the primary products of 13C label incorporation from [2-13C]glucose into glutamate, glutamine, aspartate, γ-aminobutyric acid, and N-acetylaspartate were detected. Unlike the commonly used alkanyl region where lipid signals spread over a broad frequency range, the carboxylic carbon signal of lipids was found to be confined to a narrow range centered at 172.5 ppm and present no spectral interference in the absence of lipid suppression. Comparison using phantoms shows that stochastic decoupling is far superior than the commonly used WALTZ sequence at very low decoupling power at 3 T. It was found that glutamine C1 and C5 can be decoupled using stochastic decoupling at 2.2 W although glutamine protons span a frequency range of ∼700 Hz. Detailed specific absorption rate analysis was also performed using finite difference time domain numerical simulation. PMID:19526500

  12. 13C MRS and LC–MS Flux Analysis of Tumor Intermediary Metabolism

    PubMed Central

    Shestov, Alexander A.; Lee, Seung-Cheol; Nath, Kavindra; Guo, Lili; Nelson, David S.; Roman, Jeffrey C.; Leeper, Dennis B.; Wasik, Mariusz A.; Blair, Ian A.; Glickson, Jerry D.

    2016-01-01

    We present the first validated metabolic network model for analysis of flux through key pathways of tumor intermediary metabolism, including glycolysis, the oxidative and non-oxidative arms of the pentose pyrophosphate shunt, the TCA cycle as well as its anaplerotic pathways, pyruvate–malate shuttling, glutaminolysis, and fatty acid biosynthesis and oxidation. The model that is called Bonded Cumomer Analysis for application to 13C magnetic resonance spectroscopy (13C MRS) data and Fragmented Cumomer Analysis for mass spectrometric data is a refined and efficient form of isotopomer analysis that can readily be expanded to incorporate glycogen, phospholipid, and other pathways thereby encompassing all the key pathways of tumor intermediary metabolism. Validation was achieved by demonstrating agreement of experimental measurements of the metabolic rates of oxygen consumption, glucose consumption, lactate production, and glutamate pool size with independent measurements of these parameters in cultured human DB-1 melanoma cells. These cumomer models have been applied to studies of DB-1 melanoma and DLCL2 human diffuse large B-cell lymphoma cells in culture and as xenografts in nude mice at 9.4 T. The latter studies demonstrate the potential translation of these methods to in situ studies of human tumor metabolism by MRS with stable 13C isotopically labeled substrates on instruments operating at high magnetic fields (≥7 T). The melanoma studies indicate that this tumor line obtains 51% of its ATP by mitochondrial metabolism and 49% by glycolytic metabolism under both euglycemic (5 mM glucose) and hyperglycemic conditions (26 mM glucose). While a high level of glutamine uptake is detected corresponding to ~50% of TCA cycle flux under hyperglycemic conditions, and ~100% of TCA cycle flux under euglycemic conditions, glutaminolysis flux and its contributions to ATP synthesis were very small. Studies of human lymphoma cells demonstrated that inhibition of

  13. (13)C MRS and LC-MS Flux Analysis of Tumor Intermediary Metabolism.

    PubMed

    Shestov, Alexander A; Lee, Seung-Cheol; Nath, Kavindra; Guo, Lili; Nelson, David S; Roman, Jeffrey C; Leeper, Dennis B; Wasik, Mariusz A; Blair, Ian A; Glickson, Jerry D

    2016-01-01

    We present the first validated metabolic network model for analysis of flux through key pathways of tumor intermediary metabolism, including glycolysis, the oxidative and non-oxidative arms of the pentose pyrophosphate shunt, the TCA cycle as well as its anaplerotic pathways, pyruvate-malate shuttling, glutaminolysis, and fatty acid biosynthesis and oxidation. The model that is called Bonded Cumomer Analysis for application to (13)C magnetic resonance spectroscopy ((13)C MRS) data and Fragmented Cumomer Analysis for mass spectrometric data is a refined and efficient form of isotopomer analysis that can readily be expanded to incorporate glycogen, phospholipid, and other pathways thereby encompassing all the key pathways of tumor intermediary metabolism. Validation was achieved by demonstrating agreement of experimental measurements of the metabolic rates of oxygen consumption, glucose consumption, lactate production, and glutamate pool size with independent measurements of these parameters in cultured human DB-1 melanoma cells. These cumomer models have been applied to studies of DB-1 melanoma and DLCL2 human diffuse large B-cell lymphoma cells in culture and as xenografts in nude mice at 9.4 T. The latter studies demonstrate the potential translation of these methods to in situ studies of human tumor metabolism by MRS with stable (13)C isotopically labeled substrates on instruments operating at high magnetic fields (≥7 T). The melanoma studies indicate that this tumor line obtains 51% of its ATP by mitochondrial metabolism and 49% by glycolytic metabolism under both euglycemic (5 mM glucose) and hyperglycemic conditions (26 mM glucose). While a high level of glutamine uptake is detected corresponding to ~50% of TCA cycle flux under hyperglycemic conditions, and ~100% of TCA cycle flux under euglycemic conditions, glutaminolysis flux and its contributions to ATP synthesis were very small. Studies of human lymphoma cells demonstrated that inhibition of

  14. Prospective Work for Alma: the Millimeterwave and Submillimeterwave Spectrum of 13C-GLYCOLALDEHYDE

    NASA Astrophysics Data System (ADS)

    Haykal, Imane; Margulès, Laurent; Huet, Therese R.; Motiyenko, Roman; Guillemin, J.-C.

    2011-06-01

    Glycolaldehyde has been identified in interstellar sources. The relative abundance ratios of the three isomers (acetic acid) : (glycolaldehyde) : (methylformate) were estimated . The detection of 13C_1 and 13C_2 isotopomers of methylformate has been recently reported in Orion, as a result of the detailled labororatory spectroscopic study. Therefore the spectroscopy of the 13C isotopomers of glycolaldehyde is investigated in laboratory in order to provide data for an astronomical search. The instrument ALMA will certainly be a good instrument to detect them. Up to now, only the microwave spectra of 13CH_2OH-CHO and of CH_2OH-13CHO have been observed several years ago in the 12-40 GHz range. Spectra of both species are presently recorded in Lille in the 150-950 GHz range with the new submillimetre-wave spectrometer based on harmonic generation of a microwave synthesizer source, using only solid-state devices, and coupled to a cell of 2.2 m length The absolute accuracy of the line positions is better than 30 KHz. The rotational structure of the ground state and of the three first excited vibrational states has been observed. Two 13C enriched samples were used. The analysis is in progress. This work is supported by the Programme National de Physico-Chimie du Milieu Interstellaire (PCMI-CNRS) and by the contract ANR-08-BLAN-0054 J. M. Hollis, S. N. Vogel, L. E. Snyder, et al., Astrophys. J. 554(2001) L81 R. A. H. Butler, F. C. De Lucia, D. T Petkie, et al., Astrophys. J. Supp. 134 (2001) 319 M. T. Beltran, C. Codella, S. Viti, R. Niri, R. Cesaroni, Astrophys. J. 690 (2009) L93. M. Carjaval, L. Margulès, B. Tercero et al., Astron. Astrophys. 500 (2009) 1109. K.-M. Marstokk and H. Møllendal, J. Mol. Struct. 16 (1973) 259. R. A. Motiyenko, L. Margulès, E. A. Alekseev et al., J. Mol. Spectrosc. 264 (2010) 94.

  15. High-precision position-specific isotope analysis of 13C/12C in leucine and methionine analogues.

    PubMed

    Sacks, Gavin L; Brenna, J Thomas

    2003-10-15

    We report an automated method for high-precision position-specific isotope analysis (PSIA) of carbon in amino acid analogues. Carbon isotope ratios are measured for gas-phase pyrolysis fragments from multiple sources of 3-methylthiopropylamine (3MTP) and isoamylamine (IAA), the decarboxylated analogues of methionine and leucine, using a home-built gas chromatography (GC)-pyrolysis-GC preparation system coupled to a combustion-isotope ratio mass spectrometry system. Over a temperature range of 620-900 degrees C, the characteristic pyrolysis products for 3MTP were CH4, C2H6, HCN, and CH3CN and for IAA products were propylene, isobutylene, HCN, and CH3CN. Fragment origin was confirmed by 13C-labeling, and fragments used for isotope analysis were generated from unique moieties with > 95% structural fidelity. Isotope ratios for the fragments were determined with an average precision of SD(delta13C) < 0.3% per thousand, and relative isotope ratios of fragments from different sources were determined with an average precision of SD(delta(delta)13C) < 0.5% per thousand. Delta(delta)13C values of fragments were invariant over a range of pyrolysis temperatures. The delta(delta)13C of complementary fragments in IAA was within 0.8% per thousand of the delta(delta)13C of the parent compounds, indicating that pyrolysis-induced isotopic fractionation is effectively taken into account with this calibration procedure. Using delta(delta)13C values of fragments, delta(delta)13C values were determined for all four carbon positions of 3MTP and for C1, C2, and the propyl moiety of IAA, either directly or indirectly by mass balance. Large variations in position-specific isotope ratios were observed in samples from different commercial sources. Most dramatically, two 3MTP sources differed by 16.30% per thousand at C1, 48.33% per thousand at C2, 0.37% per thousand at C3, and 5.36% per thousand at C(methyl). These PSIA techniques are suitable for studying subtle changes in intramolecular

  16. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  17. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  18. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  19. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  20. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  1. Characterisation of black carbon-rich samples by 13C solid-state nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Novotny, Etelvino H.; Hayes, Michael H. B.; Deazevedo, Eduardo R.; Bonagamba, Tito J.

    2006-09-01

    There are difficulties in quantifying and characterising the organic matter (OM) in soils that contain significant amounts of partially oxidised char or charcoal materials. The anthropogenic black carbon (BC), such as that found in the Terra Preta de Índio soils of the Amazon region, is a good example of the OM that is difficult to analyse in such soils. 13C direct polarisation/magic angle spinning (DP/MAS) at high MAS frequency, 1H-13C cross polarisation (CP)/MAS with total suppression of spinning sidebands (TOSS), and chemical shift anisotropy (CSA) filter nuclear magnetic resonance techniques have been applied successfully for quantifying the different components of OM. However, because pyrogenic materials present strong local magnetic susceptibility heterogeneities, the use of CSA-filter and TOSS make the pulse sequences very sensitive to imperfections in the π pulses. In this study, the DP/MAS pulse sequence was replaced by a CP with a radio frequency ramp—variable amplitude CP (VACP)—VACP/MAS pulse sequence, and composite π pulses were used in the CSA-filter and TOSS pulse sequences. In that way, the component functionalities in a humic acid from a BC soil were successfully determined. The spectrometer time needed was greatly decreased by employing this VACP/MAS technique. This development provides an accurate method for characterising BC-rich samples from different origins.

  2. Partial 13C isotopic enrichment of nucleoside monophosphates: useful reporters for NMR structural studies

    PubMed Central

    Kishore, Anita I.; Mayer, Michael R.; Prestegard, James H.

    2005-01-01

    Analysis of the 13C isotopic labeling patterns of nucleoside monophosphates (NMPs) extracted from Escherichia coli grown in a mixture of C-1 and C-2 glucose is presented. By comparing our results to previous observations on amino acids grown in similar media, we have been able to rationalize the labeling pattern based on the well-known biochemistry of nucleotide biosynthesis. Except for a few notable absences of label (C4 in purines and C3′ in ribose) and one highly enriched site (C1′ in ribose), most carbons are randomly enriched at a low level (an average of 13%). These sparsely labeled NMPs give less complex NMR spectra than their fully isotopically labeled analogs due to the elimination of most 13C–13C scalar couplings. The spectral simplicity is particularly advantageous when working in ordered systems, as illustrated with guanosine diphosphate (GDP) bound to ADP ribosylation factor 1 (ARF1) aligned in a liquid crystalline medium. In this system, the absence of scalar couplings and additional long-range dipolar couplings significantly enhances signal to noise and resolution. PMID:16254075

  3. Characterisation of black carbon-rich samples by (13)C solid-state nuclear magnetic resonance.

    PubMed

    Novotny, Etelvino H; Hayes, Michael H B; Deazevedo, Eduardo R; Bonagamba, Tito J

    2006-09-01

    There are difficulties in quantifying and characterising the organic matter (OM) in soils that contain significant amounts of partially oxidised char or charcoal materials. The anthropogenic black carbon (BC), such as that found in the Terra Preta de Indio soils of the Amazon region, is a good example of the OM that is difficult to analyse in such soils. (13)C direct polarisation/magic angle spinning (DP/MAS) at high MAS frequency, (1)H-(13)C cross polarisation (CP)/MAS with total suppression of spinning sidebands (TOSS), and chemical shift anisotropy (CSA) filter nuclear magnetic resonance techniques have been applied successfully for quantifying the different components of OM. However, because pyrogenic materials present strong local magnetic susceptibility heterogeneities, the use of CSA-filter and TOSS make the pulse sequences very sensitive to imperfections in the pi pulses. In this study, the DP/MAS pulse sequence was replaced by a CP with a radio frequency ramp--variable amplitude CP (VACP)--VACP/MAS pulse sequence, and composite pi pulses were used in the CSA-filter and TOSS pulse sequences. In that way, the component functionalities in a humic acid from a BC soil were successfully determined. The spectrometer time needed was greatly decreased by employing this VACP/MAS technique. This development provides an accurate method for characterising BC-rich samples from different origins. PMID:16688435

  4. Validating methods for measuring delta18O and delta13C in otoliths from freshwater fish.

    PubMed

    Guiguer, K R R A; Drimmie, R; Power, M

    2003-01-01

    The ability of the phosphoric acid digestion technique to extract carbon dioxide from biogenic carbonates and reliably reproduce delta(18)O and delta(13)C signatures from standard reference materials (NBS-18, NBS-19) was tested and shown to produce accurate, unbiased measurements of non-biologic materials. The effects of roasting preparation methods commonly reported when analyzing biogenic carbonates were also tested in a series of experiments using reference standards and otoliths obtained from aquacultured Arctic charr and rainbow trout. Roasting had no effect on the isotope measurement of reference standards. No significant differences between mean oxygen isotope signatures from paired experiments with roasted and non-roasted fish otoliths were found. However, otolith oxygen isotope measurements were significantly enriched in comparison to rearing water-based measurements for both species. Agreement between expected isotopic equilibrium and measured otolith delta(18)O values varied as a function of roasting temperature and between species. Criteria for the selection of appropriate roasting temperatures are suggested and favour 350 degrees C in freshwater fish where unbiased estimates of average rearing water temperatures and known differences in rearing temperatures were obtained. Carbon isotopic disequilibria were observed for both species. A mixing model analysis established differences in the percentage of metabolically derived carbon in studied otoliths, with Arctic charr deriving a greater proportion of otolith delta(13)C from metabolism as a result of higher metabolic rates. PMID:12590395

  5. Effect of posture on 13C-urea breath test in partial gastrectomy patients

    PubMed Central

    Yin, Shu-Ming; Zhang, Fan; Shi, Dong-Mei; Xiang, Ping; Xiao, Li; Huang, Yi-Qin; Zhang, Gan-Sheng; Bao, Zhi-Jun

    2015-01-01

    AIM: To investigate whether posture affects the accuracy of 13C-urea breath test (13C-UBT) for Helicobacter pylori (H. pylori) detection in partial gastrectomy patients. METHODS: We studied 156 consecutive residual stomach patients, including 76 with H. pylori infection (infection group) and 80 without H. pylori infection (control group). H. pylori infection was confirmed if both the rapid urease test and histology were positive during gastroscopy. The two groups were divided into four subgroups according to patients’ posture during the 13C-UBT: subgroup A, sitting position; subgroup B, supine position; subgroup C, right lateral recumbent position; and subgroup D, left lateral recumbent position. Each subject underwent the following modified 13C-UBT: 75 mg of 13C-urea (powder) in 100 mL of citric acid solution was administered, and a mouth wash was performed immediately; breath samples were then collected at baseline and at 5-min intervals up to 30 min while the position was maintained. Seven breath samples were collected for each subject. The cutoff value was 2.0‰. RESULTS: The mean delta over baseline (DOB) values in the subgroups of the infection group were similar at 5 min (P > 0.05) and significantly higher than those in the corresponding control subgroups at all time points (P < 0.01). In the infection group, the mean DOB values in subgroup A were higher than those in other subgroups within 10 min and peaked at the 10-min point (12.4‰ ± 2.4‰). The values in subgroups B and C both reached their peaks at 15 min (B, 13.9‰ ± 1.5‰; C, 12.2‰ ± 1.7‰) and then decreased gradually until the 30-min point. In subgroup D, the value peaked at 20 min (14.7‰ ± 1.7‰). Significant differences were found between the values in subgroups D and B at both 25 min (t = 2.093, P = 0.043) and 30 min (t = 2.141, P = 0.039). At 30 min, the value in subgroup D was also significantly different from those in subgroups A and C (D vs C: t = 6.325, P = 0.000; D vs A: t

  6. Soil microbial communities in a CO2-enriched and 13C-labelled treeline ecosystem with different tree species

    NASA Astrophysics Data System (ADS)

    Hiltbrunner, David; Hagedorn, Frank; Miltner, Anja; Schmidt, Michael W. I.

    2010-05-01

    The aim of this study was to estimate the responses of soil microbial communities at the alpine treeline to elevated CO2 and to gain insight into the C cycling through microbial groups under two tree species by tracking 13C signatures into phospholipid fatty acids (PLFA). In alpine treeline ecosystems, we exposed 30 year-old larch and pine trees growing on undisturbed thick mor-type organic layers to five years of elevated CO2 (+200 μmol CO2 mol-1) being depleted in 13C. Results showed that elevated CO2 increased soil respiration particularly under pine trees. However, we found negligible CO2 effects on the biomass and community structure of soil microorganisms, which might be due to small plant growth responses, and a comparatively small input of new plant-derived C into the thick organic layers with large C stocks. The tracing of 13C-depleted CO2 revealed that only a small portion of the microbial community actively metabolized new C (25%). The 13C label in individual PLFA indicated that mainly fungi were involved in the use of new substrate. Tree species affected soil microbial communities in the organic layer with a significantly higher ratio of fungal to bacterial fatty acids under pine than under larch trees. Under pine, fungal PLFA of the organic layer carried a stronger 13C label which strongly suggests a greater mycorrhizal activity that might also lead to the 60% greater input of new plant-derived C into soil organic matter under pine than under larch. In conclusion, our results show that significant responses of microbial communities in these treeline ecosystems if any would require more drastic and long lasting effects than five years of elevated CO2. Tree species have a major impact on the cycling of new plant C through soil microbial communities.

  7. Accurate measurements of {sup 13}C-{sup 13}C distances in uniformly {sup 13}C-labeled proteins using multi-dimensional four-oscillating field solid-state NMR spectroscopy

    SciTech Connect

    Straasø, Lasse Arnt; Nielsen, Jakob Toudahl; Bjerring, Morten; Nielsen, Niels Chr.; Khaneja, Navin

    2014-09-21

    Application of sets of {sup 13}C-{sup 13}C internuclear distance restraints constitutes a typical key element in determining the structure of peptides and proteins by magic-angle-spinning solid-state NMR spectroscopy. Accurate measurements of the structurally highly important {sup 13}C-{sup 13}C distances in uniformly {sup 13}C-labeled peptides and proteins, however, pose a big challenge due to the problem of dipolar truncation. Here, we present novel two-dimensional (2D) solid-state NMR experiments capable of extracting distances between carbonyl ({sup 13}C′) and aliphatic ({sup 13}C{sub aliphatic}) spins with high accuracy. The method is based on an improved version of the four-oscillating field (FOLD) technique [L. A. Straasø, M. Bjerring, N. Khaneja, and N. C. Nielsen, J. Chem. Phys. 130, 225103 (2009)] which circumvents the problem of dipolar truncation, thereby offering a base for accurate extraction of internuclear distances in many-spin systems. The ability to extract reliable accurate distances is demonstrated using one- and two-dimensional variants of the FOLD experiment on uniformly {sup 13}C,{sup 15}N-labeled-L-isoleucine. In a more challenging biological application, FOLD 2D experiments are used to determine a large number of {sup 13}C′-{sup 13}C{sub aliphatic} distances in amyloid fibrils formed by the SNNFGAILSS fibrillating core of the human islet amyloid polypeptide with uniform {sup 13}C,{sup 15}N-labeling on the FGAIL fragment.

  8. Stable isotope-enhanced two- and three-dimensional diffusion ordered 13C-NMR spectroscopy (SIE-DOSY 13C-NMR)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable Isotope-Enhanced Diffusion Ordered (SIE-DOSY) 13C-NMR has been applied to 13C-enriched carbohydrates and has been used to determine diffusion coefficients for pentose and hexose monosaccharides, a disaccharide and a trisaccharide. These 2D spectra were obtained with as little as 8 min of acq...

  9. HCCCH Experiment for Through-Bond Correlation of Thymine Resonances in 13C-Labeled DNA Oligonucleotides

    NASA Astrophysics Data System (ADS)

    Sklenář, Vladimír.; Masse, James E.; Feigon, Juli

    1999-04-01

    Application of heteronuclear magnetic resonance pulse methods to13C,15N-labeled nucleic acids is important for the accurate structure determination of larger RNA and DNA oligonucleotides and protein-nucleic acid complexes. These methods have been applied primarily to RNA, due to the availability of labeled samples. The two major differences between DNA and RNA are at the C2‧ of the ribose and deoxyribose and the additional methyl group on thymine versus uracil. We have enzymatically synthesized a13C,15N-labeled 32 base DNA oligonucleotide that folds to form an intramolecular triplex. We present two- and three-dimensional versions of a new HCCCH-TOCSY experiment that provides intraresidue correlation between the thymine H6 and methyl resonances via the intervening carbons (H6-C6-C5-Cme-Hme).

  10. Using Position-Specific 13C and 14C Labeling and 13C-PLFA Analysis to Assess Microbial Transformations of Free Versus Sorbed Alanine

    NASA Astrophysics Data System (ADS)

    Apostel, C.; Herschbach, J.; Bore, E. K.; Kuzyakov, Y.; Dippold, M. A.

    2015-12-01

    Sorption of charged or partially charged low molecular weight organic substances (LMWOS) to soil mineral surfaces delays microbial uptake and therefore mineralization of LMWOS to CO2, as well as all other biochemical transformations. We used position-specific labeling, a tool of isotope applications novel to soil sciences, to compare the transformation mechanisms of sorbed and non-sorbed alanine in soil. Alanine as an amino acid links C- and N-cycles in soil and therefore is a model substance for the pool of LMWOS. To assess transformations of sorbed alanine, we added position-specific and uniformly 13C and 14C labeled alanine tracer to soil that had previously been sterilized by γ-radiation. The labeled soil was added to non-sterilized soil from the same site and incubated. Soil labeled with the same tracers without previous sorption was prepared and incubated as well. We captured the respired CO2 and determined its 14C-activity at increasing time intervals. The incorporation of 14C into microbial biomass was determined by chloroform fumigation extraction (CFE), and utilization of individual C positions by distinct microbial groups was evaluated by 13C-phospholipid fatty acid analysis (PLFA). A dual peak in the respired CO2 revealed two sorption mechanisms. To compare the fate of individual C atoms independent of their concentration and pool size in soil, we applied the divergence index (DI). The DI reveals the convergent or divergent behavior of C from individual molecule positions during microbial utilization. Alanine C-1 position was mainly oxidized to CO2, while its C-2 and C-3 were preferentially incorporated in microbial biomass and PLFA. This indicates that sorption by the COOH group does not protect this group from preferential oxidation. Microbial metabolism was determinative for the preferential oxidation of individual molecule positions. The use of position-specific labeling revealed mechanisms and kinetics of microbial utilization of sorbed and non

  11. A novel approach to the rapid assignment of (13)C NMR spectra of major components of vegetable oils such as avocado, mango kernel and macadamia nut oils.

    PubMed

    Retief, Liezel; McKenzie, Jean M; Koch, Klaus R

    2009-09-01

    Assignment of (13)C nuclear magnetic resonance (NMR) spectra of major fatty acid components of South African produced vegetable oils was attempted using a method in which the vegetable oil was spiked with a standard triacylglycerol. This proved to be inadequate and therefore a new rapid and potentially generic graphical linear correlation method is proposed for assignment of the (13)C NMR spectra of major fatty acid components of apricot kernel, avocado pear, grapeseed, macadamia nut, mango kernel and marula vegetable oils. In this graphical correlation method, chemical shifts of fatty acids present in a known standard triacylglycerol is plotted against the corresponding chemical shifts of fatty acids present in the vegetable oils. This new approach (under carefully defined conditions and concentrations) was found especially useful for spectrally crowded regions where significant peak overlap occurs and was validated with the well-known (13)C NMR spectrum of olive oil which has been extensively reported in the literature. In this way, a full assignment of the (13)C{1H} NMR spectra of the vegetable oils, as well as tripalmitolein was readily achieved and the resonances belonging to the palmitoleic acid component of the triacylglycerols in the case of macadamia nut and avocado pear oil resonances were also assigned for the first time in the (13)C NMR spectra of these oils. PMID:19544589

  12. 13C Tracking after 13CO2 Supply Revealed Diurnal Patterns of Wood Formation in Aspen1

    PubMed Central

    Mahboubi, Amir; Linden, Pernilla; Moritz, Thomas

    2015-01-01

    Wood of trees is formed from carbon assimilated in the photosynthetic tissues. Determining the temporal dynamics of carbon assimilation, subsequent transport into developing wood, and incorporation to cell walls would further our understanding of wood formation in particular and tree growth in general. To investigate these questions, we designed a 13CO2 labeling system to study carbon transport and incorporation to developing wood of hybrid aspen (Populus tremula × tremuloides). Tracking of 13C incorporation to wood over a time course using nuclear magnetic resonance spectroscopy revealed diurnal patterns in wood cell wall biosynthesis. The dark period had a differential effect on 13C incorporation to lignin and cell wall carbohydrates. No 13C was incorporated into aromatic amino acids of cell wall proteins in the dark, suggesting that cell wall protein biosynthesis ceased during the night. The results show previously unrecognized temporal patterns in wood cell wall biosynthesis, suggest diurnal cycle as a possible cue in the regulation of carbon incorporation to wood, and establish a unique 13C labeling method for the analysis of wood formation and secondary growth in trees. PMID:25931520

  13. Conformational changes of alamethicin induced by solvent and temperature. A 13C-NMR and circular-dichroism study.

    PubMed

    Jung, G; Dubischar, N

    1975-06-01

    13C nuclear magnetic resonance (NMR) and circular dichroism (CD) have been used for studies on the conformation of alamethicin. The 13C NMR spectrum is assigned with the aid of signals of synthetic partial sequences and selective proton decoupling. The solvent and temperature-dependence of the 13C NMR spectra, T1 measurements and the use of lanthanide-shift reagents allow the differentiation between the amino acids belonging to a rigid alpha-helical portion of the alamethicin sequence and those belonging to a more flexible part. The 13C NMR results are in agreement with results obtained from extended solvent and temperature-dependent CD studies which indicate a highly stabilized nonpolar and intrachenar alpha-helical part. The concentration-dependence of the CD spectrum of alamethicin in a nematic phase revealed aggregation phenomena which might simulate those observed in natural and synthetic membranes. After dissolving alamethicin in aqueous alcohol there is a time-dependence of the ellipticity of the Cotton effects showing a sort of memory effect on the mode of dissolution. Four different conformations can be characterized by CD spectra depending on the solvent and concentration. A model illustrating the dynamic conformations and aggregation phenomena within a membrane is proposed. PMID:1175592

  14. Efficient Total Chemical Synthesis of (13) C=(18) O Isotopomers of Human Insulin for Isotope-Edited FTIR.

    PubMed

    Dhayalan, Balamurugan; Fitzpatrick, Ann; Mandal, Kalyaneswar; Whittaker, Jonathan; Weiss, Michael A; Tokmakoff, Andrei; Kent, Stephen B H

    2016-03-01

    Isotope-edited two-dimensional Fourier transform infrared spectroscopy (2 D FTIR) can potentially provide a unique probe of protein structure and dynamics. However, general methods for the site-specific incorporation of stable (13) C=(18) O labels into the polypeptide backbone of the protein molecule have not yet been established. Here we describe, as a prototype for the incorporation of specific arrays of isotope labels, the total chemical synthesis-via a key ester insulin intermediate-of 97 % enriched [(1-(13) C=(18) O)Phe(B24) ] human insulin: stable-isotope labeled at a single backbone amide carbonyl. The amino acid sequence as well as the positions of the disulfide bonds and the correctly folded structure were unambiguously confirmed by the X-ray crystal structure of the synthetic protein molecule. In vitro assays of the isotope labeled [(1-(13) C=(18) O)Phe(B24) ] human insulin showed that it had full insulin receptor binding activity. Linear and 2 D IR spectra revealed a distinct red-shifted amide I carbonyl band peak at 1595 cm(-1) resulting from the (1-(13) C=(18) O)Phe(B24) backbone label. This work illustrates the utility of chemical synthesis to enable the application of advanced physical methods for the elucidation of the molecular basis of protein function. PMID:26715336

  15. Determination of fructose metabolic pathways in normal and fructose-intolerant children: A sup 13 C NMR study using (U- sup 13 C)fructose

    SciTech Connect

    Gopher, A.; Lapidot, A. ); Vaisman, N. ); Mandel, H. )

    1990-07-01

    An inborn deficiency in the ability of aldolase B to split fructose 1-phosphate is found in humans with hereditary fructose intolerance (HFI). A stable isotope procedure to elucidate the mechanism of conversion of fructose to glucose in normal children and in HFI children has been developed. A constant infusion of D-(U-{sup 13}C)fructose was given nasogastrically to control and to HFI children. Hepatic fructose conversion to glucose was estimated by examination of {sup 13}C NMR spectra of plasma glucose. Significantly lower values ({approx}3-fold) for fructose conversion to glucose were obtained for the HFI patients as compared to the controls. A quantitative determination of the metabolic pathways of fructose conversion to glucose was derived from {sup 13}C NMR measurement of plasma ({sup 13}C)glucose isotopomer populations. The finding of isotopomer populations of three adjacent {sup 13}C atoms at glucose C-4 ({sup 13}C{sub 3}-{sup 13}C{sub 4}-{sup 13}C{sub 5}) suggests that there is a direct pathway from fructose, by-passing fructose-1-phosphate aldolase, to fructose 1,6-bisphosphate. The metabolism of fructose by fructose-1-phosphate aldolase activity accounts for only {approx}50% of the total amount of hepatic fructose conversion to glucose. In view of the marked decline by 67% in synthesis of glucose from fructose in HFI subjects found in this study, the extent of ({sup 13}C)glucose formation from a trace amount of (U-{sup 13}C)fructose infused into the patient can be used as a safe and noninvasive diagnostic test for inherent faulty fructose metabolism.

  16. Topological Constraints on Chain-Folding Structure of Semicrystalline Polymer as Studied by 13C-13C Double Quantum NMR

    NASA Astrophysics Data System (ADS)

    Hong, Youlee; Miyoshi, Toshikazu

    Chain-folding process is a prominent feature of long polymer chains during crystallization. Over the last half century, much effort has been paid to reveal the chain trajectory. Even though various chain-folding models as well as theories of crystallization at molecule levels have been proposed, they could be not reconciled due to the limited experimental evidences. Recent development of double quantum NMR with selective isotope labeling identified the chain-trajectory of 13C labeled isotactic poly(1-butene). The systematic experiments covered a wide range of parameters, i.e. kinetics, concentration, and molecular weight (Mw) . It was demonstrated that i) adjacent re-entry site was invariant as a function of crystallization temperature (Tc) , concentration, andMw, ii) long-range order of adjacent re-entry sequence is independence of kinetics at a given concentration while it decreased with increasing the polymer concentration at a given Tc due to the increased interruption between the chains, and iii) high Mw chains led to the multilayer folded structures in single crystals, but the melt state induced the identical short adjacent sequences of long and short polymer over a wide range of Tc due to the entanglements. The behaviors indicated that the topological restriction plays significant roles in the chain-folding process rather than the kinetics. The proposed framework to control the chain-folding structure presents a new perspective into the chain organization by either the intra- or inter-chain interaction. National Science Foundation Grants DMR-1105829 and 1408855.

  17. Geochemical Approach to Archaeal Ecology: δ13C of GDGTs

    NASA Astrophysics Data System (ADS)

    Lichtin, S.; Warren, C.; Pearson, A.; Pagani, M.

    2015-12-01

    Over the last decade and a half, glycerol dialkyl glycerol tetraethers (GDGTs) have increasingly been used to reconstruct environmental temperatures; proxies like TEX86 that correlate the relative abundance of these archaeal cell membrane lipids to sea surface temperature are omnipresent in paleoclimatology literature. While it has become common to make claims about past temperatures using GDGTs, our present understanding of the organisms that synthesize the compounds is still quite limited. The generally accepted theory states that microorganisms like the Thaumarchaeota modify the structure of membrane lipids to increase intermolecular interactions, strengthening the membrane at higher temperatures. Yet to date, culture experiments have been largely restricted to a single species, Nitrosopumilus maritimes, and recent studies on oceanic archaeal rRNA have revealed that these biomarkers are produced in diverse, heterogeneous, and site-specific communities. This brings up questions as to whether different subclasses of GDGTs, and all subsequent proxies, represent adaptation within a single organismal group or a shift in community composition. To investigate whether GDGTs with different chain structures, from the simple isoprenoidal GDGT-0 to Crenarchaeol with its many cyclopentane groups, are sourced from archaea with similar or disparate metabolic pathways—and if that information is inherited in GDGTs trapped in marine sediments—this study examines the stable carbon isotope values (δ13C) of GDGTs extracted from the uppermost meters of sediment in the Orca Basin, Gulf of Mexico, using spooling-wire microcombustion isotope-ratio mass spectrometer (SWiM-IRMS), tackling a fundamental assumption of the TEX86 proxy that influences the way we perceive the veracity of existing temperature records.

  18. Fluxomers: a new approach for 13C metabolic flux analysis

    PubMed Central

    2011-01-01

    Background The ability to perform quantitative studies using isotope tracers and metabolic flux analysis (MFA) is critical for detecting pathway bottlenecks and elucidating network regulation in biological systems, especially those that have been engineered to alter their native metabolic capacities. Mathematically, MFA models are traditionally formulated using separate state variables for reaction fluxes and isotopomer abundances. Analysis of isotope labeling experiments using this set of variables results in a non-convex optimization problem that suffers from both implementation complexity and convergence problems. Results This article addresses the mathematical and computational formulation of 13C MFA models using a new set of variables referred to as fluxomers. These composite variables combine both fluxes and isotopomer abundances, which results in a simply-posed formulation and an improved error model that is insensitive to isotopomer measurement normalization. A powerful fluxomer iterative algorithm (FIA) is developed and applied to solve the MFA optimization problem. For moderate-sized networks, the algorithm is shown to outperform the commonly used 13CFLUX cumomer-based algorithm and the more recently introduced OpenFLUX software that relies upon an elementary metabolite unit (EMU) network decomposition, both in terms of convergence time and output variability. Conclusions Substantial improvements in convergence time and statistical quality of results can be achieved by applying fluxomer variables and the FIA algorithm to compute best-fit solutions to MFA models. We expect that the fluxomer formulation will provide a more suitable basis for future algorithms that analyze very large scale networks and design optimal isotope labeling experiments. PMID:21846358

  19. Nic1 Inactivation Enables Stable Isotope Labeling with 13C615N4-Arginine in Schizosaccharomyces pombe*

    PubMed Central

    Carpy, Alejandro; Patel, Avinash; Tay, Ye Dee; Hagan, Iain M.; Macek, Boris

    2015-01-01

    Stable Isotope Labeling by Amino Acids (SILAC) is a commonly used method in quantitative proteomics. Because of compatibility with trypsin digestion, arginine and lysine are the most widely used amino acids for SILAC labeling. We observed that Schizosaccharomyces pombe (fission yeast) cannot be labeled with a specific form of arginine, 13C615N4-arginine (Arg-10), which limits the exploitation of SILAC technology in this model organism. We hypothesized that in the fission yeast the guanidinium group of 13C615N4-arginine is catabolized by arginase and urease activity to 15N1-labeled ammonia that is used as a precursor for general amino acid biosynthesis. We show that disruption of Ni2+-dependent urease activity, through deletion of the sole Ni2+ transporter Nic1, blocks this recycling in ammonium-supplemented EMMG medium to enable 13C615N4-arginine labeling for SILAC strategies in S. pombe. Finally, we employed Arg-10 in a triple-SILAC experiment to perform quantitative comparison of G1 + S, M, and G2 cell cycle phases in S. pombe. PMID:25368411

  20. Use of 13C Nuclear Magnetic Resonance To Assess Fossil Fuel Biodegradation: Fate of [1-13C]Acenaphthene in Creosote Polycyclic Aromatic Compound Mixtures Degraded by Bacteria†

    PubMed Central

    Selifonov, Sergey A.; Chapman, Peter J.; Akkerman, Simon B.; Gurst, Jerome E.; Bortiatynski, Jacqueline M.; Nanny, Mark A.; Hatcher, Patrick G.

    1998-01-01

    [1-13C]acenaphthene, a tracer compound with a nuclear magnetic resonance (NMR)-active nucleus at the C-1 position, has been employed in conjunction with a standard broad-band-decoupled 13C-NMR spectroscopy technique to study the biodegradation of acenaphthene by various bacterial cultures degrading aromatic hydrocarbons of creosote. Site-specific labeling at the benzylic position of acenaphthene allows 13C-NMR detection of chemical changes due to initial oxidations catalyzed by bacterial enzymes of aromatic hydrocarbon catabolism. Biodegradation of [1-13C]acenaphthene in the presence of naphthalene or creosote polycyclic aromatic compounds (PACs) was examined with an undefined mixed bacterial culture (established by enrichment on creosote PACs) and with isolates of individual naphthalene- and phenanthrene-degrading strains from this culture. From 13C-NMR spectra of extractable materials obtained in time course biodegradation experiments under optimized conditions, a number of signals were assigned to accumulated products such as 1-acenaphthenol, 1-acenaphthenone, acenaphthene-1,2-diol and naphthalene 1,8-dicarboxylic acid, formed by benzylic oxidation of acenaphthene and subsequent reactions. Limited degradation of acenaphthene could be attributed to its oxidation by naphthalene 1,2-dioxygenase or related dioxygenases, indicative of certain limitations of the undefined mixed culture with respect to acenaphthene catabolism. Coinoculation of the mixed culture with cells of acenaphthene-grown strain Pseudomonas sp. strain A2279 mitigated the accumulation of partial transformation products and resulted in more complete degradation of acenaphthene. This study demonstrates the value of the stable isotope labeling approach and its ability to reveal incomplete mineralization even when as little as 2 to 3% of the substrate is incompletely oxidized, yielding products of partial transformation. The approach outlined may prove useful in assessing bioremediation performance

  1. Sc3CH@C80: selective 13C enrichment of the central carbon atom†

    PubMed Central

    Junghans, Katrin; Rosenkranz, Marco; Popov, Alexey A.

    2016-01-01

    Sc3CH@C80 is synthesized and characterized by 1H, 13C, and 45Sc NMR. A large negative chemical shift of the proton, −11.73 ppm in the Ih and −8.79 ppm in the D5h C80 cage isomers, is found. 13C satellites in the 1H NMR spectrum enabled indirect determination of the 13C chemical shift for the central carbon at 173 ± 1 ppm. Intensity of the satellites allowed determination of the 13C content for the central carbon atom. This unique possibility is applied to analyze the cluster/cage 13C distribution in mechanistic studies employing either 13CH4 or 13C powder to enrich Sc3CH@C80 with 13C. PMID:27109443

  2. Sc3CH@C80: selective (13)C enrichment of the central carbon atom.

    PubMed

    Junghans, Katrin; Rosenkranz, Marco; Popov, Alexey A

    2016-05-01

    Sc3CH@C80 is synthesized and characterized by (1)H, (13)C, and (45)Sc NMR. A large negative chemical shift of the proton, -11.73 ppm in the Ih and -8.79 ppm in the D5h C80 cage isomers, is found. (13)C satellites in the (1)H NMR spectrum enabled indirect determination of the (13)C chemical shift for the central carbon at 173 ± 1 ppm. Intensity of the satellites allowed determination of the (13)C content for the central carbon atom. This unique possibility is applied to analyze the cluster/cage (13)C distribution in mechanistic studies employing either (13)CH4 or (13)C powder to enrich Sc3CH@C80 with (13)C. PMID:27109443

  3. Seasonal variations of dissolved inorganic carbon and δ13C of surface waters: application of a modified gas evolution technique

    NASA Astrophysics Data System (ADS)

    Atekwana, E. A.; Krishnamurthy, R. V.

    1998-03-01

    Seasonal concentrations and δ13C of dissolved inorganic carbon (DIC) in a river-tributary system in Kalamazoo, southwest Michigan, USA, have been measured using a modified gas evolution technique. The technique makes use of evacuated glass septum tubes pre-loaded with phosphoric acid and a magnetic stir bar. Water samples are injected into these septum tubes in the field, which eliminates problems associated with CO 2 loss/gain during sample storage and transfer to the vacuum line during DIC extraction. Using this technique, a precision of 1% and 0.1‰ can be achieved for DIC concentrations and δ13C DIC measurements, respectively. As this technique provides reliable measurements of DIC concentrations and carbon isotope ratios, it was used to evaluate the processes that control DIC in the river-tributary system. Results of DIC concentration and δ13C DIC measurements of water samples from the river-tributary system show that the DIC pool is mostly dominated by groundwater. The DIC concentrations and δ13C DIC are within the ranges measured for the most isotopically evolved groundwater in this region. Seasonal variations superimposed on the baseline values are attributed to secondary processes such as CO 2 invasion from the atmosphere, enhanced recharge from lakes and biological activities of photosynthesis, respiration, and decay. With the onset of spring, there is a concurrent increase in the DIC concentration and δ13C DIC of these streams. A simultaneous increase in concentration and 13C enrichment of the riverine DIC pool is consistent with CO 2 invasion and recharge from lakes. During the summer, biological activity is the predominant control on shifts in the DIC pool. Although photosynthesis, respiration and decay occur during this time, decreases in the DIC concentration and increases in the 13C DIC indicates CO 2 removal from the pool by photosynthesis. In the late summer-early fall, photosynthesis declines and respiration and decay cause an increase in

  4. Computational Platform for Flux Analysis Using 13C-Label Tracing- Phase I SBIR Final Report

    SciTech Connect

    Van Dien, Stephen J.

    2005-04-12

    Isotopic label tracing is a powerful experimental technique that can be combined with metabolic models to quantify metabolic fluxes in an organism under a particular set of growth conditions. In this work we constructed a genome-scale metabolic model of Methylobacterium extorquens, a facultative methylotroph with potential application in the production of useful chemicals from methanol. A series of labeling experiments were performed using 13C-methanol, and the resulting distribution of labeled carbon in the proteinogenic amino acids was determined by mass spectrometry. Algorithms were developed to analyze this data in context of the metabolic model, yielding flux distributions for wild-type and several engineered strains of M. extorquens. These fluxes were compared to those predicted by model simulation alone, and also integrated with microarray data to give an improved understanding of the metabolic physiology of this organism.

  5. 13C-n.m.r. of the cyanylated apoflavodoxin and flavodoxin from Clostridium pasteurianum.

    PubMed Central

    Doherty, G M; Mayhew, S G; Malthouse, J P

    1993-01-01

    The thiol group of the flavodoxin from Clostridium pasteurianum has been cyanylated in a single step using [cyanato-13C]2-nitro-5-thiocyanatobenzoic acid. This chemical modification increases the dissociation constant of the apoflavodoxin-FMN complex 10-fold from 0.33 +/- 0.15 nM to 2.9 +/- 1.3 nM. The thiocyanate carbons of the cyanylated cysteine residue of apoflavodoxin and flavodoxin had chemical shift values of 114.7 and 112.3 p.p.m. respectively. From these chemical shifts we conclude that the binding of FMN by the cyanylated apoflavodoxin causes a decrease in the polarity and/or hydrogen bonding capacity of the environment of the thiocyanate group. We compare these results with those obtained from similar studies on the cyanylated apoflavodoxin and flavodoxin from Megasphaera elsdenii and we discuss how FMN binding and cyanylation perturb the structures of apoflavodoxins from Megasphaera elsdenii and Clostridium pasteurianum. PMID:8363575

  6. Quantitative solid-state 13C NMR with signal enhancement by multiple cross polarization

    NASA Astrophysics Data System (ADS)

    Johnson, Robert L.; Schmidt-Rohr, Klaus

    2014-02-01

    A simple new method is presented that yields quantitative solid-state magic-angle spinning (MAS) 13C NMR spectra of organic materials with good signal-to-noise ratios. It achieves long (>10 ms) cross polarization (CP) from 1H without significant magnetization losses due to relaxation and with a moderate duty cycle of the radio-frequency irradiation, by multiple 1-ms CP periods alternating with 1H spin-lattice relaxation periods that repolarize the protons. The new method incorporates previous techniques that yield less distorted CP/MAS spectra, such as a linear variation (“ramp”) of the radio-frequency field strength, and it overcomes their main limitation, which is T1ρ relaxation of the spin-locked 1H magnetization. The ramp of the radio-frequency field strength and the asymptotic limit of cross polarization makes the spectral intensity quite insensitive to the exact field strengths used. The new multiCP pulse sequence is a “drop-in” replacement for previous CP methods and produces no additional data-processing burden. Compared to the only reliable quantitative 13C NMR method for unlabeled solids previously available, namely direct-polarization NMR, the measuring time is reduced by more than a factor of 50, enabling higher-throughput quantitative NMR studies. The new multiCP technique is validated with 14-kHz MAS on amino-acid derivatives, plant matter, a highly aromatic humic acid, and carbon materials made by low-temperature pyrolysis.

  7. 13C NMR Metabolomic Evaluation of Immediate and Delayed Mild Hypothermia in Cerebrocortical Slices After Oxygen-Glucose Deprivation

    PubMed Central

    Liu, Jia; Segal, Mark; Kelly, Mark J.S.; Pelton, Jeffrey G.; Kim, Myungwon; James, Thomas L.; Litt, Lawrence

    2013-01-01

    Background Mild brain hypothermia (32°C–34°C) after human neonatal asphyxia improves neurodevelopmental outcomes. Astrocytes but not neurons have pyruvate carboxylase (PC) and an acetate uptake transporter. 13C NMR spectroscopy of rodent brain extracts after administering [1-13C]glucose and [1,2-13C]acetate can distinguish metabolic differences between glia and neurons, and tricarboxylic acid cycle (TCA cycle) entry via pyruvate dehydrogenase (PDH) and PC. Methods Neonatal rat cerebrocortical slices receiving a 13C-acetate/glucose mixture underwent a 45-min asphyxia simulation via oxygen-glucose-deprivation (OGD) followed by 6 h of recovery. Protocols in three groups of N = 3 experiments were identical except for temperature management. The three temperature groups were: normothermia (37°C), hypothermia (32°C for 3.75 h beginning at OGD start), and delayed hypothermia (32°C for 3.75 h, beginning 15 min after OGD start). Multivariate analysis of nuclear magnetic resonance metabolite quantifications included principal component analyses and the L1-Penalized Regularized Regression algorithm known as the Least Absolute Shrinkage and Selection Operator (LASSO). Results The most significant metabolite difference (p < 0.0056) was [2-13C]glutamine’s higher final/control ratio for the Hypothermia group (1.75 ± 0.12) compared to ratios for the Delayed (1.12 ± 0.12) and Normothermia group (0.94 ± 0.06), implying a higher PC/PDH ratio for glutamine formation. LASSO found the most important metabolites associated with adenosine triphosphate preservation: [3,4-13C]glutamate—produced via PDH entry, [2-13C]taurine--an important osmolyte, and phosphocreatine. Final principal component analyses scores plots suggested separate cluster formation for the hypothermia group, but with insufficient data for statistical significance. Conclusions Starting mild hypothermia simultaneously with OGD, compared with delayed starting or no hypothermia, has higher PC throughput

  8. Performance evaluation of quantitative adiabatic (13)C NMR pulse sequences for site-specific isotopic measurements.

    PubMed

    Thibaudeau, Christophe; Remaud, Gérald; Silvestre, Virginie; Akoka, Serge

    2010-07-01

    (2)H/(1)H and (13)C/(12)C site-specific isotope ratios determined by NMR spectroscopy may be used to discriminate pharmaceutically active ingredients based on the synthetic process used in production. Extending the Site-specific Natural Isotope Fractionation NMR (SNIF-NMR) method to (13)C is highly beneficial for complex organic molecules when measurements of (2)H/(1)H ratios lead to poorly defined molecular fingerprints. The current NMR methodology to determine (13)C/(12)C site-specific isotope ratios suffers from poor sensitivity and long experimental times. In this work, several NMR pulse sequences based on polarization transfer were evaluated and optimized to measure precise quantitative (13)C NMR spectra within a short time. Adiabatic 180 degrees (1)H and (13)C pulses were incorporated into distortionless enhancement by polarization transfer (DEPT) and refocused insensitive nuclei enhanced by polarization transfer (INEPT) to minimize the influence of 180 degrees pulse imperfections and of off-resonance effects on the precision of the measured (13)C peak areas. The adiabatic DEPT sequence was applied to draw up a precise site-specific (13)C isotope profile of ibuprofen. A modified heteronuclear cross-polarization (HCP) experiment featuring (1)H and (13)C spin-locks with adiabatic 180 degrees pulses is also introduced. This sequence enables efficient magnetization transfer across a wide (13)C frequency range although not enough for an application in quantitative (13)C isotopic analysis. PMID:20527737

  9. Analysis of hyperpolarized dynamic 13C lactate imaging in a transgenic mouse model of prostate cancer☆

    PubMed Central

    Lupo, Janine M.; Chen, Albert P.; Zierhut, Matthew L.; Bok, Robert A.; Cunningham, Charles H.; Kurhanewicz, John; Vigneron, Daniel B.; Nelson, Sarah J.

    2011-01-01

    This study investigated the application of an acquisition that selectively excites the [1-13C]lactate resonance and allows dynamic tracking of the conversion of 13C-lactate from hyperpolarized 13C-pyruvate at a high spatial resolution. In order to characterize metabolic processes occurring in a mouse model of prostate cancer, 20 sequential 3D images of 13C-lactate were acquired 5 s apart using a pulse sequence that incorporated a spectral–spatial excitation pulse and a flyback echo-planar readout to track the time course of newly converted 13C-lactate after injection of prepolarized 13C-pyruvate. The maximum lactate signal (MLS), full-width half-maximum (FWHM), time to the peak 13C-lactate signal (TTP) and area under the dynamic curve were calculated from the dynamic images of 10 TRAMP mice and two wild-type controls. The regional variation in 13C-lactate associated with the injected pyruvate was demonstrated by the peak of the 13C-lactate signal occurring earlier in the kidney than in the tumor region. The intensity of the dynamic 13C-lactate curves also varied spatially within the tumor, illustrating the heterogeneity in metabolism that was most prominent in more advanced stages of disease development. The MLS was significantly higher in TRAMP mice that had advanced disease. PMID:19695815

  10. Assessing microbial utilization of free versus sorbed Alanine by using position-specific 13C labeling and 13C-PLFA analysis

    NASA Astrophysics Data System (ADS)

    Herschbach, Jennifer; Apostel, Carolin; Spielvogel, Sandra; Kuzyakov, Yakov; Dippold, Michaela

    2016-04-01

    Microbial utilization is a key transformation process of soil organic matter (SOM). Sorption of low molecular weight organic substances (LMWOS) to soil mineral surfaces blocks or delays microbial uptake and therefore mineralization of LMWOS to CO2, as well as all other biochemical transformations. We used position-specific labeling, a tool of isotope applications novel to soil science, combined with 13C-phospholipid fatty acid (PLFA) analysis, to assess microbial utilization of sorbed and non-sorbed Alanine in soil. Alanine has various functional groups enabling different sorption mechanisms via its positive charge (e.g. to clay minerals by cation exchange), as well as via its negative charge (e.g. to iron oxides by ligand exchange). To assess changes in the transformation pathways caused by sorption, we added uniformly and position-specifically 13C and 14C labeled Alanine to the Ap of a loamy Luvisol in a short-term (10 days) incubation experiment. To allow for sorption of the tracer solution to an aliquot of this soil, microbial activity was minimized in this subsample by sterilizing the soil by γ-radiation. After shaking, the remaining solutions were filtered and the non-sorbed Alanine was removed with Millipore water and then added to non-sterilized soil. For the free Alanine treatment, solutions with Alanine of similar amount and isotopic composition were prepared, added to the soil and incubated as well. The respired CO2 was trapped in NaOH and its 14C-activity was determined at increasing times intervals. Microbial utilization of Alanine's individual C positions was evaluated in distinct microbial groups classified by 13C-PLFA analysis. Sorption to soil minerals delayed respiration to CO2 and reduced initial respiration rate by 80%. Irrespective of sorption, the highest amount was respired from the carboxylic position (C-1), whereas the amino-bound (C-2) and the methylic position (C-3) were preferentially incorporated into PLFA of microorganisms due to the

  11. Quantifying the Contribution of Grape Hexoses to Wine Volatiles by High-Precision [U13C]-Glucose Tracer Studies

    PubMed Central

    Nisbet, Mark A.; Tobias, Herbert J.; Brenna, J. Thomas; Sacks, Gavin L.; Mansfield, Anna Katharine

    2016-01-01

    Many fermentation volatiles important to wine aroma potentially arise from yeast metabolism of hexose sugars, but assessing the relative importance of these pathways is challenging due to high endogenous hexose substrate concentrations. To overcome this problem, gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS) was used to measure high-precision 13C/12C isotope ratios of volatiles in wines produced from juices spiked with tracer levels (0.01–1 APE) of uniformly labeled [U-13C]-glucose. The contribution of hexose to individual volatiles was determined from the degree of 13C enrichment. As expected, straight-chain fatty acids and their corresponding ethyl esters were derived almost exclusively from hexoses. Most fusel alcohols and their acetate esters were also majority hexose-derived, indicating the importance of anabolic pathways for their formation. Only two compounds were not derived primarily from hexoses (hexanol and isobutyric acid). This approach can be extended to other food systems or substrates for studying precursor–product relationships. PMID:24960193

  12. Theoretical Calibration on the 13C-18O Clumped Isotope Thermometer

    NASA Astrophysics Data System (ADS)

    Tang, M.; Zhang, S. T.; LIU, Q.; Liu, Y.

    2014-12-01

    The kinetic isotope effect (KIE) arisen from phosphoric acid digestion of carbonates has been noticed since the beginning of stable isotope geochemistry. However, the molecular level details of this reaction have not been fully understood yet. Equilibrium 13C-18O clumped isotope distribution in carbonates has been suggested as a new thermometer for surface temperature systems; nevertheless, existing Δ47-T relationships calibrated by several different groups are incompatible, generating substantial confusions and debates about those variations. Here we propose a new molecular-level mechanism with three parallel pathways for the phosphoric acid digestion of carbonates. We show that the KIE of such reaction can be different if the relative contributions of the three parallel pathways are changed. This new mechanism abandons completely a previously proposed molecular mechanism (i.e., Guo et al., 2009) and can explain (at least partly) why the Δ47-T relationships provided by different groups are different. Together with a re-calculated equilibrium clumped isotope fractionation factors of carbonate minerals using a new volume-variable-cluster-model method with higher theoretical-level treatments and higher-order anharmonic corrections, we present a theoretical (equilibrium + KIE) Δ47-T relationship for carbonates. Our theoretical calibration line is with large variations due to considering possible changes of relative contributions of the three parallel pathways and different carbonate mineral used. For minimizing the variation, we suggest using the same amount of sample, the same mineral and the same temperature of phosphoric acid digestion for this experiment.

  13. Photosynthesis and sup 13 C/ sup 12 C ratios in Amazonian rain forests

    SciTech Connect

    Van Der Merwe, N.J. ); Medina, E. )

    1989-05-01

    Measurements are reported of {sup 13}C/{sup 12}C ratios for air CO{sub 2} at different heights in two Amazonian rain forests. CO{sub 2} emitted from the forest floor is severely depleted in {sup 13}C which produces isotopically light source air throughout the forest. Air {delta}{sup 13}C values vary very little with height above ground, but are about 5 to 6{per thousand} more negative than the open atmosphere. CO{sub 2} recycling under the canopy depletes all leaf {delta}{sup 13}C values by a like amount. Additional factors further deplete leaf {delta}{sup 13}C values by 4 to 5{per thousand} at ground level; this effect decreases with height to zero in the upper canopy, yielding a gradient in {delta}{sup 13}C values.

  14. Site-specific 13C content by quantitative isotopic 13C nuclear magnetic resonance spectrometry: a pilot inter-laboratory study.

    PubMed

    Chaintreau, Alain; Fieber, Wolfgang; Sommer, Horst; Gilbert, Alexis; Yamada, Keita; Yoshida, Naohiro; Pagelot, Alain; Moskau, Detlef; Moreno, Aitor; Schleucher, Jürgen; Reniero, Fabiano; Holland, Margaret; Guillou, Claude; Silvestre, Virginie; Akoka, Serge; Remaud, Gérald S

    2013-07-25

    Isotopic (13)C NMR spectrometry, which is able to measure intra-molecular (13)C composition, is of emerging demand because of the new information provided by the (13)C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic (13)C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular (13)C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic (13)C NMR was then assessed on vanillin from three different origins associated with specific δ (13)Ci profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ (13)Ci in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results. PMID:23845488

  15. Biosynthesis of highly enriched 13C-lycopene for human metabolic studies using repeated batch tomato cell culturing with 13C-glucose

    PubMed Central

    Moran, Nancy E.; Rogers, Randy B.; Lu, Chi-Hua; Conlon, Lauren E.; Lila, Mary Ann; Clinton, Steven K.; Erdman, John W.

    2013-01-01

    While putative disease-preventing lycopene metabolites are found in both tomato (Solanum lycopersicum) products and in their consumers, mammalian lycopene metabolism is poorly understood. Advances in tomato cell culturing techniques offer an economical tool for generation of highly-enriched 13C-lycopene for human bioavailability and metabolism studies. To enhance the 13C-enrichment and yields of labeled lycopene from the hp-1 tomato cell line, cultures were first grown in 13C-glucose media for three serial batches and produced increasing proportions of uniformly labeled lycopene (14.3 +/− 1.2 %, 39.6 +/− 0.5 %, and 48.9 +/− 1.5% with consistent yields (from 5.8 to 9 mg/L). An optimized 9-day-long 13C-loading and 18-day-long labeling strategy developed based on glucose utilization and lycopene yields, yielded 13C-lycopene with 93% 13C isotopic purity, and 55% of isotopomers were uniformly labeled. Furthermore, an optimized acetone and hexane extraction led to a four-fold increase in lycopene recovery from cultures compared to a standard extraction. PMID:23561155

  16. Coupling and higher-order effects in the {sup 12}C(d,p){sup 13}C and {sup 13}C(p,d){sup 12}C reactions

    SciTech Connect

    Delaunay, F.; Nunes, F.M.; Lynch, W.G.; Tsang, M.B.

    2005-07-01

    Coupled-channel calculations are performed for the {sup 12}C(d,p){sup 13}C and {sup 13}C(p,d){sup 12}C reactions between 7 and 60 MeV to study the effect of inelastic couplings in transfer reactions. The effect of treating transfer beyond Born approximation is also addressed. The coupling to the {sup 12}C 2{sup +} state is found to change the peak cross section by up to 15%. Effects beyond Born approximation lead to a significant renormalization of the cross sections, between 5% and 10% for deuteron energies above 10 MeV and larger than 10% for lower energies. We also performed calculations including the remnant term in the transfer operator, which has a small impact on the {sup 12}C(d,p){sup 13}C(g.s.) and {sup 13}C(p,d){sup 12}C(g.s.) reactions (where g.s. indicates ground state). Above 30-MeV deuteron energy, the effect of the remnant term is larger than 10% for the {sup 12}C(d,p){sup 13}C(1/2{sup +}, 3.09 MeV) reaction and is found to increase with decreasing neutron separation energy for the 3.09-MeV state of {sup 13}C. This is of importance for transfer reactions with weakly bound nuclei.

  17. A highly sensitive assay for xanthine oxidoreductase activity using a combination of [(13) C2 ,(15) N2 ]xanthine and liquid chromatography/triple quadrupole mass spectrometry.

    PubMed

    Murase, Takayo; Oka, Mitsuru; Nampei, Mai; Miyachi, Atsushi; Nakamura, Takashi

    2016-05-15

    In this study, we developed a highly sensitive assay for xanthine oxidoreductase (XOR) activity utilizing a combination of [(13) C2 ,(15) N2 ]xanthine and liquid chromatography (LC)/triple quadrupole mass spectrometry (TQMS). In this assay, the amount of [(13) C2 ,(15) N2 ]uric acid (UA) produced by XOR was determined by using LC/TQMS. For this assay, we synthesized [(13) C2 ,(15) N2 ]xanthine as a substrate, [(13) C2 ,(15) N2 ]UA as an analytical standard, and [(13) C3 ,(15) N3 ]UA as an internal standard. The [(13) C2 ,(15) N2 ]UA calibration curve obtained using LC/TQMS under the selected reaction monitoring mode was evaluated, and the results indicated good linearity (R(2)  = 0.998, weighting of 1/x(2) ) in the range of 20 to 4000 nM. As a model reaction of less active samples, the XOR activity of serial-diluted mouse plasma was measured. Thereby, the XOR activity of the 1024-fold-diluted mouse plasma was 4.49 ± 0.44 pmol/100 μL/h (mean ± standard deviation, n = 3). This value is comparable to the predicted XOR activity value of healthy human plasma. Hence, this combination method may be used to obtain high-sensitivity measurements required for XOR activity analysis on various organs or human plasma. PMID:27006202

  18. Determination of Oxidative Glucose Metabolism in vivo in the Young Rat Brain using Localized Direct-detected 13C NMR Spectroscopy

    PubMed Central

    Ennis, Kathleen; Deelchand, Dinesh Kumar; Tkac, Ivan; Henry, Pierre-Gilles; Rao, Raghavendra

    2011-01-01

    Determination of oxidative metabolism in the brain using in vivo 13C NMR spectroscopy (13C MRS) typically requires repeated blood sampling throughout the study to measure blood glucose concentration and fractional enrichment (input function). However, drawing blood from small animals, such as young rats, placed deep inside the magnet is technically difficult due to their small total blood volume. In the present study, a custom-built animal holder enabled temporary removal of the animal from the magnet for blood collection, followed by accurate repositioning in the exact presampling position without degradation of B0 shimming. 13C label incorporation into glutamate C4 and C3 positions during a 120 min [1,6-13C2] glucose infusion was determined in 28-day-old rats (n = 4) under α-chloralose sedation using localized, direct-detected in vivo 13C MRS at 9.4T. The tricarboxylic acid cycle activity rate (VTCA) determined using a one-compartment metabolic modeling was 0.67 ± 0.13 µmol/g/min, a value comparable to previous ex vivo studies. This methodology opens the avenue for in vivo measurements of brain metabolic rates using 13C MRS in small animals. PMID:21660589

  19. Galacto-oligosaccharides have prebiotic activity in a dynamic in vitro colon model using a (13)C-labeling technique.

    PubMed

    Maathuis, Annet J H; van den Heuvel, Ellen G; Schoterman, Margriet H C; Venema, Koen

    2012-07-01

    Galacto-oligosaccharides (GOS) are considered to be prebiotic, although the contribution of specific members of the microbiota to GOS fermentation and the exact microbial metabolites that are produced upon GOS fermentation are largely unknown. We aimed to determine this using uniformly (13)C-labeled GOS. The normal (control) medium and unlabeled or (13)C-labeled GOS was added to a dynamic, validated, in vitro model of the large-intestine containing an adult-type microbiota. Liquid-chromatography MS was used to measure the incorporation of (13)C label into metabolites. 16S-rRNA stable isotope probing coupled to a phylogenetic micro-array was used to determine label incorporation in microbial biomass. The primary members within the complex microbiota that were directly involved in GOS fermentation were shown to be Bifidobacterium longum, B. bifidum, B. catenulatum, Lactobacillus gasseri, and L. salivarius, in line with the prebiotic effect of GOS, although some other species incorporated (13)C label also. GOS fermentation led to an increase in acetate (+49%) and lactate (+23%) compared with the control. Total organic acid production was 8.50 and 7.52 mmol/g of carbohydrate fed for the GOS and control experiments, respectively. At the same time, the cumulative production of putrefactive metabolites (branched-chain fatty acids and ammonia) was reduced by 55%. Cross-feeding of metabolites from primary GOS fermenters to other members of the microbiota was observed. Our findings support a prebiotic role for GOS and its potential to act as a synbiotic in combination with certain probiotic strains. PMID:22623395

  20. Glutamatergic and GABAergic energy metabolism measured in the rat brain by (13) C NMR spectroscopy at 14.1 T.

    PubMed

    Duarte, João M N; Gruetter, Rolf

    2013-09-01

    Energy metabolism supports both inhibitory and excitatory neurotransmission processes. This study investigated the specific contribution of astrocytic metabolism to γ-aminobutyric acid (GABA) synthesis and inhibitory GABAergic neurotransmission that remained to be ilucidated in vivo. Therefore, we measured (13)C incorporation into brain metabolites by dynamic (13)C nuclear magnetic resonance spectroscopy at 14.1 T in rats under α-chloralose anaesthesia during infusion of [1,6-(13)C]glucose. The enhanced sensitivity at 14.1 T allowed to quantify incorporation of (13) C into the three aliphatic carbons of GABA non-invasively. Metabolic fluxes were determined with a mathematical model of brain metabolism comprising glial, glutamatergic and GABAergic compartments. GABA synthesis rate was 0.11 ± 0.01 μmol/g/min. GABA-glutamine cycle was 0.053 ± 0.003 μmol/g/min and accounted for 22 ± 1% of total neurotransmitter cycling between neurons and glia. Cerebral glucose oxidation was 0.47 ± 0.02 μmol/g/min, of which 35 ± 1% and 7 ± 1% was diverted to the glutamatergic and GABAergic tricarboxylic acid cycles, respectively. The remaining fraction of glucose oxidation was in glia, where 12 ± 1% of the TCA cycle flux was dedicated to oxidation of GABA. 16 ± 2% of glutamine synthesis was provided to GABAergic neurons. We conclude that substantial metabolic activity occurs in GABAergic neurons and that glial metabolism supports both glutamatergic and GABAergic neurons in the living rat brain. PMID:23745684

  1. A large metabolic carbon contribution to the δ 13C record in marine aragonitic bivalve shells

    NASA Astrophysics Data System (ADS)

    Gillikin, David P.; Lorrain, Anne; Meng, Li; Dehairs, Frank

    2007-06-01

    It is well known that the incorporation of isotopically light metabolic carbon (C M) significantly affects the stable carbon isotope (δ 13C) signal recorded in biogenic carbonates. This can obscure the record of δ 13C of seawater dissolved inorganic carbon (δ 13C DIC) potentially archived in the shell carbonate. To assess the C M contribution to Mercenaria mercenaria shells collected in North Carolina, USA, we sampled seawater δ 13C DIC, tissue, hemolymph and shell δ 13C. All shells showed an ontogenic decrease in shell δ 13C, with as much as a 4‰ decrease over the lifespan of the clam. There was no apparent ontogenic change in food source indicated by soft tissue δ 13C values, therefore a change in the respired δ 13C value cannot be the cause of this decrease. Hemolymph δ 13C, on the other hand, did exhibit a negative relationship with shell height indicating that respired CO 2 does influence the δ 13C value of internal fluids and that the amount of respired CO 2 is related to the size or age of the bivalve. The percent metabolic C incorporated into the shell (%C M) was significantly higher (up to 37%, with a range from 5% to 37%) than has been found in other bivalve shells, which usually contain less than 10%C M. Interestingly, the hemolymph did contain less than 10%C M, suggesting that complex fractionation might occur between hemolymph and calcifying fluids. Simple shell biometrics explained nearly 60% of the observed variability in %C M, however, this is not robust enough to predict %C M for fossil shells. Thus, the metabolic effect on shell δ 13C cannot easily be accounted for to allow reliable δ 13C DIC reconstructions. However, there does seem to be a common effect of size, as all sites had indistinguishable slopes between the %C M and shell height (+0.19% per mm of shell height).

  2. Metabolic Flux Elucidation for Large-Scale Models Using 13C Labeled Isotopes

    PubMed Central

    Suthers, Patrick F.; Burgard, Anthony P.; Dasika, Madhukar S.; Nowroozi, Farnaz; Van Dien, Stephen; Keasling, Jay D.; Maranas, Costas D.

    2007-01-01

    A key consideration in metabolic engineering is the determination of fluxes of the metabolites within the cell. This determination provides an unambiguous description of metabolism before and/or after engineering interventions. Here, we present a computational framework that combines a constraint-based modeling framework with isotopic label tracing on a large-scale. When cells are fed a growth substrate with certain carbon positions labeled with 13C, the distribution of this label in the intracellular metabolites can be calculated based on the known biochemistry of the participating pathways. Most labeling studies focus on skeletal representations of central metabolism and ignore many flux routes that could contribute to the observed isotopic labeling patterns. In contrast, our approach investigates the importance of carrying out isotopic labeling studies using a more comprehensive reaction network consisting of 350 fluxes and 184 metabolites in Escherichia coli including global metabolite balances on cofactors such as ATP, NADH, and NADPH. The proposed procedure is demonstrated on an E. coli strain engineered to produce amorphadiene, a precursor to the anti-malarial drug artemisinin. The cells were grown in continuous culture on glucose containing 20% [U-13C]glucose; the measurements are made using GC-MS performed on 13 amino acids extracted from the cells. We identify flux distributions for which the calculated labeling patterns agree well with the measurements alluding to the accuracy of the network reconstruction. Furthermore, we explore the robustness of the flux calculations to variability in the experimental MS measurements, as well as highlight the key experimental measurements necessary for flux determination. Finally, we discuss the effect of reducing the model, as well as shed light onto the customization of the developed computational framework to other systems. PMID:17632026

  3. Regional, seasonal and interspecific variation in 15N and 13C in sympatric mouse lemurs

    NASA Astrophysics Data System (ADS)

    Rakotondranary, S. Jacques; Struck, Ulrich; Knoblauch, Christian; Ganzhorn, Jörg U.

    2011-11-01

    Madagascar provides some of the rare examples where two or more primate species of the same genus and with seemingly identical niche requirements occur in sympatry. If congeneric primate species co-occur in other parts of the world, they differ in size in a way that is consistent with Hutchinson's rule for coexisting species, or they occupy different ecological niches. In some areas of Madagascar, mouse lemurs do not follow these "rules" and thus seem to violate one of the principles of community ecology. In order to understand the mechanisms that allow coexistence of sympatric congeneric species without obvious niche differentiation, we studied food composition of two identical sized omnivorous mouse lemur species, Microcebus griseorufus and M. murinus with the help of stable isotope analyses ( δ 15N and δ 13C). The two species are closely related sister species. During the rich season, when food seems abundant, the two species do not differ in their nitrogen isotope composition, indicating that the two species occupy the same trophic level. But they differ in their δ 13C values, indicating that M. griseorufus feeds more on C4 and CAM (Crassulacean-acid-metabolism) plants than M. murinus. During the lean season, M. murinus has lower δ 15N values, indicating that the two species feed at different trophic levels during times of food shortage. Hybrids between the two species showed intermediate food composition. The results reflect subtle differences in foraging or metabolic adaptations that are difficult to quantify by traditional observations but that represent possibilities to allow coexistence of species.

  4. Measuring (13)C-(2)D dipolar couplings with a universal REDOR dephasing curve

    PubMed

    Gullion

    2000-09-01

    A (13)C-observe REDOR experiment is described which allows (13)C-(2)D dipolar couplings to be obtained by a universal dipolar dephasing curve. Previous (13)C-observe REDOR experiments on (13)C-(2)D spin pairs generally relied on numerical simulations to obtain the dipolar coupling. The REDOR experiment described in this article is based on a deuterium composite pulse, and the data analysis eliminates the need for numerical simulations and is the same as the traditional REDOR analysis performed on pairs of spin-12 nuclei. Copyright 2000 Academic Press. PMID:10968975

  5. Open-Source Automated Parahydrogen Hyperpolarizer for Molecular Imaging Using (13)C Metabolic Contrast Agents.

    PubMed

    Coffey, Aaron M; Shchepin, Roman V; Truong, Milton L; Wilkens, Ken; Pham, Wellington; Chekmenev, Eduard Y

    2016-08-16

    An open-source hyperpolarizer producing (13)C hyperpolarized contrast agents using parahydrogen induced polarization (PHIP) for biomedical and other applications is presented. This PHIP hyperpolarizer utilizes an Arduino microcontroller in conjunction with a readily modified graphical user interface written in the open-source processing software environment to completely control the PHIP hyperpolarization process including remotely triggering an NMR spectrometer for efficient production of payloads of hyperpolarized contrast agent and in situ quality assurance of the produced hyperpolarization. Key advantages of this hyperpolarizer include: (i) use of open-source software and hardware seamlessly allowing for replication and further improvement as well as readily customizable integration with other NMR spectrometers or MRI scanners (i.e., this is a multiplatform design), (ii) relatively low cost and robustness, and (iii) in situ detection capability and complete automation. The device performance is demonstrated by production of a dose (∼2-3 mL) of hyperpolarized (13)C-succinate with %P13C ∼ 28% and 30 mM concentration and (13)C-phospholactate at %P13C ∼ 15% and 25 mM concentration in aqueous medium. These contrast agents are used for ultrafast molecular imaging and spectroscopy at 4.7 and 0.0475 T. In particular, the conversion of hyperpolarized (13)C-phospholactate to (13)C-lactate in vivo is used here to demonstrate the feasibility of ultrafast multislice (13)C MRI after tail vein injection of hyperpolarized (13)C-phospholactate in mice. PMID:27478927

  6. Sub-second Proton Imaging of 13C Hyperpolarized Contrast Agents in Water

    PubMed Central

    Truong, Milton L.; Coffey, Aaron M.; Shchepin, Roman V.; Waddell, Kevin W.; Chekmenev, Eduard Y.

    2014-01-01

    Indirect proton detection of 13C hyperpolarized contrast agents potentially enables greater sensitivity. Presented here is a study of sub-second projection imaging of hyperpolarized 13C contrast agent addressing the obstacle posed by water suppression for indirect detection in vivo. Sodium acetate phantoms were used to develop and test water suppression and sub-second imaging with frequency selective RF pulses using spectroscopic and imaging indirect proton detection. A 9.8 mM aqueous solution of 13C PHIP hyperpolarized 2-hydroxyethyl-13C-propionate-d2,3,3 (HEP),

    ~25% was used for demonstration of indirect proton sub-second imaging detection. Balanced 2D FSSFP (Fast Steady State Free Precession) allowed recording proton images with FOV = 64×64 mm2 and spatial resolution 2×2 mm2 with total acquisition time of less than 0.2 s. In thermally polarized sodium 1-13C-acetate, 13C to 1H polarization transfer efficiency of 45.1% of the theoretically predicted values was observed in imaging detection corresponding to an 11 fold of overall sensitivity improvement compared to direct 13C FSSFP imaging. 13C to 1H polarization transfer efficiency of 27% was observed in imaging detection corresponding to a 3.25 fold sensitivity improvement compared to direct 13C FSSFP imaging with hyperpolarized HEP. The range of potential applications and limitations of this sub-second and ultra-sensitive imaging approach are discussed. PMID:24753438

  7. Lack of 13C-label incorporation suggests low turnover rates of thaumarchaeal intact polar tetraether lipids in sediments from the Iceland Shelf

    NASA Astrophysics Data System (ADS)

    Lengger, S. K.; Lipsewers, Y. A.; de Haas, H.; Sinninghe Damsté, J. S.; Schouten, S.

    2013-08-01

    Thaumarchaeota are amongst the most abundant microorganisms in aquatic environments, however, their metabolism in marine sediments is still debated. Labeling studies in marine sediments have previously been undertaken, but focused on complex organic carbon substrates which Thaumarchaeota have not yet been shown to take up. In this study, we investigated the activity of Thaumarchaeota in sediments by supplying different 13C-labeled substrates which have previously been shown to be incorporated into archaeal cells in water incubations and/or enrichment cultures. We determined the incorporation of 13C-label from bicarbonate, pyruvate, glucose and amino acids into thaumarchaeal intact polar lipid-glycerol dibiphytanyl glycerol tetraethers (IPL-GDGTs) during 4-6 day incubations of marine sediment cores from three different sites on the Iceland Shelf. Thaumarchaeal intact polar lipids were detected at all stations and concentrations remained constant or decreased slightly upon incubation. No 13C incorporation in any IPL-GDGT was observed at stations 2 (clay-rich sediment) and 3 (organic-rich sediment). In bacterial/eukaryotic IPL-derived fatty acids at station 3, contrastingly, a large uptake of 13C label (up to +80‰) was found. 13C was also respired during the experiment as shown by a substantial increase in the 13C content of the dissolved inorganic carbon. In IPL-GDGTs recovered from the sandy sediments at station 1, however, some enrichment in 13C (1-4‰) was detected after incubation with bicarbonate and pyruvate. The low incorporation rates suggest a low activity of Thaumarchaeota in marine sediments and/or a low turnover rate of thaumarchaeal IPL-GDGTs due to their low degradation rates. Cell numbers and activity of sedimentary Thaumarchaeota based on IPL-GDGT measurements may thus have previously been overestimated.

  8. Lack of 13C-label incorporation suggests low turnover rates of thaumarchaeal intact polar tetraether lipids in sediments from the Iceland shelf

    NASA Astrophysics Data System (ADS)

    Lengger, S. K.; Lipsewers, Y. A.; de Haas, H.; Sinninghe Damsté, J. S.; Schouten, S.

    2014-01-01

    Thaumarchaeota are amongst the most abundant microorganisms in aquatic environments, however, their metabolism in marine sediments is still debated. Labeling studies in marine sediments have previously been undertaken, but focused on complex organic carbon substrates which Thaumarchaeota have not yet been shown to take up. In this study, we investigated the activity of Thaumarchaeota in sediments by supplying different 13C-labeled substrates which have previously been shown to be incorporated into archaeal cells in water incubations and/or enrichment cultures. We determined the incorporation of 13C-label from bicarbonate, pyruvate, glucose and amino acids into thaumarchaeal intact polar lipid-glycerol dibiphytanyl glycerol tetraethers (IPL-GDGTs) during 4-6 day incubations of marine sediment cores from three sites on the Iceland shelf. Thaumarchaeal intact polar lipids, in particular crenarchaeol, were detected at all stations and concentrations remained constant or decreased slightly upon incubation. No 13C incorporation in any IPL-GDGT was observed at stations 2 (clay-rich sediment) and 3 (organic-rich sediment). In bacterial/eukaryotic IPL-derived fatty acids at station 3, contrastingly, a large uptake of 13C label (up to + 80‰ ) was found. 13C was also respired during the experiment as shown by a substantial increase in the 13C content of the dissolved inorganic carbon. In IPL-GDGTs recovered from the sandy sediments at station 1, however, some enrichment in δ13C (1-4‰ ) was detected after incubation with bicarbonate and pyruvate. The low incorporation rates suggest a low activity of Thaumarchaeota in marine sediments and/or a low turnover rate of thaumarchaeal IPL-GDGTs due to their low degradation rates. Cell numbers and activity of sedimentary Thaumarchaeota based on IPL-GDGT measurements may thus have previously been overestimated.

  9. Monitoring creatine and phosphocreatine by (13)C MR spectroscopic imaging during and after (13)C4 creatine loading: a feasibility study.

    PubMed

    Janssen, Barbara H; Lassche, Saskia; Hopman, Maria T; Wevers, Ron A; van Engelen, Baziel G M; Heerschap, Arend

    2016-08-01

    Creatine (Cr) supplementation to enhance muscle performance shows variable responses among individuals and different muscles. Direct monitoring of the supplied Cr in muscles would address these differences. In this feasibility study, we introduce in vivo 3D (13)C MR spectroscopic imaging (MRSI) of the leg with oral ingestion of (13)C4-creatine to observe simultaneously Cr and phosphocreatine (PCr) for assessing Cr uptake, turnover, and the ratio PCr over total Cr (TCr) in individual muscles. (13)C MRSI was performed of five muscles in the posterior thigh in seven subjects (two males and two females of ~20 years, one 82-year-old male, and two neuromuscular patients) with a (1)H/(13)C coil in a 3T MR system before, during and after intake of 15 % (13)C4-enriched Cr. Subjects ingested 20 g Cr/day for 4 days in four 5 g doses at equal time intervals. The PCr/TCr did not vary significantly during supplementation and was similar for all subjects and investigated muscles (average 0.71 ± 0.07), except for the adductor magnus (0.64 ± 0.03). The average Cr turnover rate, assessed in male muscles, was 2.1 ± 0.7 %/day. The linear uptake rates of Cr were variable between muscles, although not significantly different. This assessment was possible in all investigated muscles of young male volunteers, but less so in muscles of the other subjects due to lower signal-to-noise ratio. Improvements for future studies are discussed. In vivo (13)C MRSI after (13)C-Cr ingestion is demonstrated for longitudinal studies of Cr uptake, turnover, and PCr/TCr ratios of individual muscles in one exam. PMID:27401085

  10. Photobioreactor design for isotopic non-stationary 13C-metabolic flux analysis (INST 13C-MFA) under photoautotrophic conditions.

    PubMed

    Martzolff, Arnaud; Cahoreau, Edern; Cogne, Guillaume; Peyriga, Lindsay; Portais, Jean-Charles; Dechandol, Emmanuel; Le Grand, Fabienne; Massou, Stéphane; Gonçalves, Olivier; Pruvost, Jérémy; Legrand, Jack

    2012-12-01

    Adaptive metabolic behavior of photoautotrophic microorganisms toward genetic and environmental perturbations can be interpreted in a quantitative depiction of carbon flow through a biochemical reaction network using isotopic non-stationary (13) C-metabolic flux analysis (INST (13) C-MFA). To evaluate (13) C-metabolic flux maps for Chlamydomonas reinhardtii, an original experimental framework was designed allowing rapid, reliable collection of high-quality isotopomer data against time. It involved (i) a short-time (13) C labeling injection device based on mixing control in a torus-shaped photobioreactor with plug-flow hydrodynamics allowing a sudden step-change in the (13) C proportion in the substrate feed and (ii) a rapid sampling procedure using an automatic fast filtration method coupled to a manual rapid liquid nitrogen quenching step. (13) C-substrate labeling enrichment was controlled through the total dissolved inorganic carbon concentration in the pulsed solution. First results were obtained from steady-state continuous culture measurements allowing the characterization of the kinetics of label incorporation into light-limited growing cells cultivated in a photobioreactor operating at the maximal biomass productivity for an incident photon flux density of 200 µmol m(-2) s(-1). (13)C label incorporation was measured for 21 intracellular metabolites using IC-MS/MS in 58 samples collected across a labeling experiment duration of 7 min. The fastest labeling rate was observed for 2/3-phosphoglycerate with an apparent isotopic stationary state reached after 300 s. The labeling rate was consistent with the optimized mixing time of about 4.9 s inside the reactor and the shortest reliable sampling period assessed at 5 s. PMID:22688667

  11. Chitosan-poly(acrylic) acid polyionic complex: in vivo study to demonstrate prolonged gastric retention.

    PubMed

    Torrado, Susana; Prada, Pablo; de la Torre, Paloma M; Torrado, Santiago

    2004-02-01

    The aim of this study was to develop a chitosan-poly(acrylic) acid based controlled drug release system for gastric antibiotic delivery. Different mixtures of amoxicillin (A), chitosan (CS), and poly(acrylic) acid (PAA) were employed to obtain these polyionic complexes. A non-invasive method was employed for determining the gastric residence time of the formulations. It was studied the swelling behavior and drug release from these complexes. Gastric emptying rate study was performed by means of the [13C]octanoic acid breath test. The gastric emptying rates of two different formulations (conventional and gastric retentive system) were studied. Swelling studies indicated that the extent of swelling was greater in the polyionic complexes than in the single chitosan formulations. The amoxicillin diffusion from the hydrogels was controlled by the polymer/drug interaction. The property of these complexes to control the solute diffusion depends on the network mesh size, which is a significant factor in the overall behavior of the hydrogels. The gastric half-emptying time of the polyionic complex was significantly delayed compared to the reference formulation, showing mean values of 164.32+/-26.72 and 65.06+/-11.50min, respectively (P<0.01). The results of this study suggest that, these polyionic complexes are good systems for specific gastric drug delivery. PMID:14609680

  12. A Large Metabolic Carbon Ccontribution to the δ13C Record in Marine Aragonitic Bivalve Shells

    NASA Astrophysics Data System (ADS)

    Gillikin, D. P.; Lorrain, A.; Dehairs, F.

    2006-12-01

    The stable carbon isotopic signature archived in bivalve shells was originally thought to record the δ13C of seawater dissolved inorganic carbon (δ13C-DIC). However, more recent studies have shown that the incorporation of isotopically light metabolic carbon (M) significantly affects the δ13C signal recorded in biogenic carbonates. To assess the M contribution to Mercenaria mercenaria shells collected in North Carolina, USA, we sampled seawater δ13C-DIC, tissue, hemolymph and shell δ13C. We found up to a 4‰ decrease through ontogeny in shell δ13C in a 23 year old individual. There was no correlation between shell height or age and tissue δ13C. Thus, the ontogenic decrease observed in the shell δ13C could not be attributed to changes in food sources as the animal ages leading to more negative metabolic CO2, since this would require a negative relationship between tissue δ13C and shell height. Hemolymph δ13C, on the other hand, did exhibit a negative relationship with height, but the δ13C values were more positive than expected, indicating that hemolymph may not be a good proxy of extrapallial fluid δ13C. Nevertheless, the hemolymph data indicate that respired CO2 does influence the δ13C of internal fluids and that the amount of respired CO2 is related to the age of the bivalve. The percent metabolic C incorporated into the shell (%M) was significantly higher (up to 37%) than has been found in other bivalve shells, which usually contain less than 10 %M. Attempts to use shell biometrics to predict %M could not explain more than ~60% of the observed variability. Moreover, there were large differences in the %M between different sites. Thus, the metabolic effect on shell δ13C cannot easily be accounted for to allow reliable δ13C-DIC reconstructions. However, there does seem to be a common effect of size, as all sites had indistinguishable slopes between the %M and shell height (+0.19% per mm of shell height).

  13. Metabolism of hyperpolarized [1-(13) C]pyruvate through alternate pathways in rat liver.

    PubMed

    Jin, Eunsook S; Moreno, Karlos X; Wang, Jian-Xiong; Fidelino, Leila; Merritt, Matthew E; Sherry, A Dean; Malloy, Craig R

    2016-04-01

    The source of hyperpolarized (HP) [(13) C]bicarbonate in the liver during metabolism of HP [1-(13) C]pyruvate is uncertain and likely changes with physiology. Multiple processes including decarboxylation through pyruvate dehydrogenase or pyruvate carboxylase followed by subsequent decarboxylation via phosphoenolpyruvate carboxykinase (gluconeogenesis) could play a role. Here we tested which metabolic fate of pyruvate contributed to the appearance of HP [(13) C]bicarbonate during metabolism of HP [1-(13) C]pyruvate by the liver in rats after 21 h of fasting compared to rats with free access to food. The (13) C NMR of HP [(13) C]bicarbonate was observed in the liver of fed rats, but not in fasted rats where pyruvate carboxylation and gluconeogenesis was active. To further explore the relative fluxes through pyruvate carboxylase versus pyruvate dehydrogenase in the liver under typical conditions of hyperpolarization studies, separate parallel experiments were performed with rats given non-hyperpolarized [2,3-(13) C]pyruvate. (13) C NMR analysis of glutamate isolated from the liver of rats revealed that flux from injected pyruvate through pyruvate dehydrogenase was dominant under fed conditions whereas flux through pyruvate carboxylase dominated under fasted conditions. The NMR signal of HP [(13) C]bicarbonate does not parallel pyruvate carboxylase activity followed by subsequent decarboxylation reaction leading to glucose production. In the liver of healthy well-fed rats, the appearance of HP [(13) C]bicarbonate exclusively reflects decarboxylation of HP [1-(13) C]pyruvate via pyruvate dehydrogenase. © 2016 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd. PMID:26836042

  14. Effects of sampling method on foliar δ (13)C of Leymus chinensis at different scales.

    PubMed

    Liu, Yanjie; Li, Yan; Zhang, Lirong; Xu, Xingliang; Niu, Haishan

    2015-03-01

    Stable carbon isotope composition (δ (13)C) usually shows a negative relationship with precipitation at a large scale. We hypothesized that sampling method affects foliar δ (13)C and its response pattern to precipitation. We selected 11 sites along a precipitation gradient in Inner Mongolia and collected leaves of Leymus chinensis with five or six replications repeatedly in each site from 2009 to 2011. Additionally, we collected leaves of L. chinensis separately from two types of grassland (grazed and fenced) in 2011. Foliar δ (13)C values of all samples were measured. We compared the patterns that foliar δ (13)C to precipitation among different years or different sample sizes, the differences of foliar δ (13)C between grazed and fenced grassland. Whether actual annual precipitation (AAP) or mean annual precipitation (MAP), it was strongly correlated with foliar δ (13)C every year. Significant difference was found between the slopes of foliar δ (13)C to AAP and MAP every year, among the slopes of foliar δ (13)C to AAP from 2009 to 2011. The more samples used at each site the lower and convergent P-values of the linear regression test between foliar δ (13)C and precipitation. Furthermore, there was significant lower foliar δ (13)C value in presence of grazed type than fenced type grassland. These findings provide evidence that there is significant effect of sampling method to foliar δ (13)C and its response pattern to precipitation of L. chinensis. Our results have valuable implications in methodology for future field sampling studies. PMID:25798224

  15. Robust hyperpolarized (13)C metabolic imaging with selective non-excitation of pyruvate (SNEP).

    PubMed

    Chen, Way Cherng; Teo, Xing Qi; Lee, Man Ying; Radda, George K; Lee, Philip

    2015-08-01

    In vivo metabolic imaging using hyperpolarized [1-(13)C]pyruvate provides localized biochemical information and is particularly useful in detecting early disease changes, as well as monitoring disease progression and treatment response. However, a major limitation of hyperpolarized magnetization is its unrecoverable decay, due not only to T1 relaxation but also to radio-frequency (RF) excitation. RF excitation schemes used in metabolic imaging must therefore be able to utilize available hyperpolarized magnetization efficiently and robustly for the optimal detection of substrate and metabolite activities. In this work, a novel RF excitation scheme called selective non-excitation of pyruvate (SNEP) is presented. This excitation scheme involves the use of a spectral selective RF pulse to specifically exclude the excitation of [1-(13)C]pyruvate, while uniformly exciting the key metabolites of interest (namely [1-(13)C]lactate and [1-(13)C]alanine) and [1-(13)C]pyruvate-hydrate. By eliminating the loss of hyperpolarized [1-(13)C]pyruvate magnetization due to RF excitation, the signal from downstream metabolite pools is increased together with enhanced dynamic range. Simulation results, together with phantom measurements and in vivo experiments, demonstrated the improvement in signal-to-noise ratio (SNR) and the extension of the lifetime of the [1-(13)C]lactate and [1-(13)C]alanine pools when compared with conventional non-spectral selective (NS) excitation. SNEP has also been shown to perform comparably well with multi-band (MB) excitation, yet SNEP possesses distinct advantages, including ease of implementation, less stringent demands on gradient performance, increased robustness to frequency drifts and B0 inhomogeneity as well as easier quantification involving the use of [1-(13)C]pyruvate-hydrate as a proxy for the actual [1-(13)C] pyruvate signal. SNEP is therefore a promising alternative for robust hyperpolarized [1-(13)C]pyruvate metabolic imaging with high

  16. The Nature of Carbonate and Organic δ13C Covariance Through Geological Time

    NASA Astrophysics Data System (ADS)

    Oehlert, A. M.; Swart, P. K.

    2014-12-01

    Significant evolutionary, climatic, and oceanographic events in Earth history are often accompanied by excursions in the carbon isotope composition (δ13C) of marine carbonates and co-occurring sedimentary organic material. The observation of synchronous excursions in the δ13C values of marine carbonates and coeval organic matter is commonly thought to prove that the deposit has not been altered by diagenesis, and that the variations in the δ13C records are the result of a significant change in global carbon cycling. Furthermore, this model suggests that the covariance of carbonate and organic δ13C records is driven only by changes in the δ13C value of the dissolved inorganic carbon in the surface waters of the ocean. However, recent work suggests that there may be at least two alternate models for generating covariance between carbonate and organic δ13C values in the geologic record. One of the models invokes sea-level driven syndepositional mixing between isotopically distinct sources of carbonate and organic material to produce positive covariance between carbonate and organic δ13C values. The second model suggests that post-depositional alteration to the carbonate δ13C values during meteoric diagenesis, in concert with concurrent contributions of terrestrial organic material during subaerial exposure, can also produce co-occurring negative excursions with tightly covariant δ13C records. In contrast to earlier interpretations of covariant δ13C values, these models suggest that both syndepositional and post-depositional factors can significantly influence the relationship between carbonate and organic δ13C values in a variety of depositional environments. The implications for reconstructions of ancient global carbon cycle events will be explored within the context of these three models, and their relative importance throughout geologic time will be discussed.

  17. The influence of diet on the δ 13C of shell carbon in the pulmonate snail Helix aspersa

    NASA Astrophysics Data System (ADS)

    Stott, Lowell D.

    2002-02-01

    The influence of diet and atmospheric CO 2 on the carbon isotope composition of shell aragonite and shell-bound organic carbon in the pulmonate snail Helix aspersa raised in the laboratory was investigated. Three separate groups of snails were raised on romaine lettuce (C3 plant, δ 13C=-25.8‰), corn (C4 plant, δ 13C=-10.5‰), and sour orange ( 12C-enriched C3 plant, δ 13C=-39.1‰). The isotopic composition of body tissues closely tracked the isotopic composition of the snail diet as demonstrated previously. However, the isotopic composition of the acid insoluble organic matrix extracted from the aragonite shells does not track diet in all groups. In snails that were fed corn the isotopic composition of the organic matrix was more negative than the body by as much as 5‰ whereas the matrix was approximately 1‰ heavier than the body tissues in snails fed a diet of C3 plant material. These results indicate that isotopic composition of the organic matrix carbon cannot be used as an isotopic substrate for paleodietary reconstructions without first determining the source of the carbon and any associated fractionations. The isotopic composition of the shell aragonite is offset from the body tissues by 12.3‰ in each of the culture groups. This offset was not influenced by the consumption of carbonate and is not attributable to the diffusion of atmospheric CO 2 into the hemolymph. The carbon isotopic composition of shell aragonite is best explained in terms of equilibrium fractionations associated with exchange between metabolic CO 2 and HCO 3 in the hemolymph and the fractionation associated with carbonate precipitation. These results differ from previous studies, based primarily on samples collected in the field, that have suggested atmospheric carbon dioxide contributes significantly to the shell δ 13C. The culture results indicate that the δ 13C of aragonite is a good recorder of the isotopic composition of the snail body tissue, and therefore a better

  18. Reduced glutamate neurotransmission in patients with Alzheimer's disease -- an in vivo (13)C magnetic resonance spectroscopy study.

    PubMed

    Lin, Alexander P; Shic, Frederick; Enriquez, Cathleen; Ross, Brian D

    2003-02-01

    Cognitive impairment in Alzheimer's disease (AD) is not fully explained. PET indicates reduced cerebral metabolic rate for glucose. Since glutamate neurotransmission (GNT) consumes more than 80% of the ATP generated from metabolism, a pilot study was carried out to determine the neuronal tricarboxylic acid cycle (TCA) based on the hypothesis that reduced GNT could contribute to cognitive impairment in AD. Three AD patients with cognitive impairment (mini-mental state exam: 24 vs 30, P<0.05) and significant reduction in both N-acetyl aspartate (NAA)/Creatine (Cr) ( P<0.009) and NAA/myo-inositol (mI) ratio ( P<0.01), and three age-matched controls each received 0.014-0.016 g/kg/min 99%1-13C glucose IV. Quantitative (1)H and proton-decoupled (13)C MR brain spectra were acquired from combined posterior-parietal white matter and posterior-cingulate gray matter every 5 min for 140 min.(13)C magnetic resonance spectroscopy (MRS) measures of glucose oxidation and neuronal TCA rate, including prolonged time to (13)C enrichment of glutamate (Glu2) ( P<0.004) and bicarbonate (HCO(3)) ( P<0.03) as well as reduced relative enrichment of Glu(2)/Glu(4) between 60 and 100 min ( P<0.04), were significantly different in AD patients vs. controls. (13)C measures of GNT, glutamine (Gln)(2)/Glu(2) ( P<0.02) and rates of glutamate enrichment (Glu(2)/glucose: 0.34 vs 0.86, P=ns and Glu(4)/glucose 0.26 vs 0.83, P=ns), were also reduced.(13)C MRS measures of neuronal TCA cycle, glucose oxidation and GNT were significantly correlated with measures of neuronal integrity: NAA/Cr, [NAA] and mI/NAA as determined by (1)H MRS ( R(2)=0.73-0.95; P<0.05-0.01), suggesting that impairment of GNT may be a contributing factor in the cognitive impairment characteristic of AD. PMID:12695884

  19. Isotopically nonstationary 13C flux analysis of Myc-induced metabolic reprogramming in B-cells

    PubMed Central

    Murphy, Taylor A.; Dang, Chi V.; Young, Jamey D.

    2012-01-01

    We assessed several methods of 13C metabolic flux analysis (MFA) and found that isotopically nonstationary MFA achieved maximum flux resolution in cultured P493-6 B-cells, which have been engineered to provide tunable expression of the Myc oncoprotein. Comparison of metabolic flux maps obtained under oncogenic (High) and endogenous (Low) Myc expression levels revealed network-wide reprogramming in response to ectopic Myc expression. High Myc cells relied more heavily on mitochondrial oxidative metabolism than Low Myc cells and globally upregulated their consumption of amino acids relative to glucose. TCA cycle and amphibolic mitochondrial pathways exhibited 2- to 4-fold flux increases in High Myc cells, in contrast to modest increases in glucose uptake and lactate excretion. Because our MFA approach relied exclusively upon isotopic measurements of protein-bound amino acids and RNA-bound ribose, it is readily applicable to more complex tumor models that are not amenable to direct extraction and isotopic analysis of free intracellular metabolites. PMID:22898717

  20. Genome-Based Metabolic Mapping and 13C Flux Analysis Reveal Systematic Properties of an Oleaginous Microalga Chlorella protothecoides

    DOE PAGESBeta

    Wu, Chao; Xiong, Wei; Dai, Junbiao; Wu, Qingyu

    2014-12-15

    We report that integrated and genome-based flux balance analysis, metabolomics, and 13C-label profiling of phototrophic and heterotrophic metabolism in Chlorella protothecoides, an oleaginous green alga for biofuel. The green alga Chlorella protothecoides, capable of autotrophic and heterotrophic growth with rapid lipid synthesis, is a promising candidate for biofuel production. Based on the newly available genome knowledge of the alga, we reconstructed the compartmentalized metabolic network consisting of 272 metabolic reactions, 270 enzymes, and 461 encoding genes and simulated the growth in different cultivation conditions with flux balance analysis. Phenotype-phase plane analysis shows conditions achieving theoretical maximum of the biomass andmore » corresponding fatty acid-producing rate for phototrophic cells (the ratio of photon uptake rate to CO2 uptake rate equals 8.4) and heterotrophic ones (the glucose uptake rate to O2 consumption rate reaches 2.4), respectively. Isotope-assisted liquid chromatography-mass spectrometry/mass spectrometry reveals higher metabolite concentrations in the glycolytic pathway and the tricarboxylic acid cycle in heterotrophic cells compared with autotrophic cells. We also observed enhanced levels of ATP, nicotinamide adenine dinucleotide (phosphate), reduced, acetyl-Coenzyme A, and malonyl-Coenzyme A in heterotrophic cells consistently, consistent with a strong activity of lipid synthesis. To profile the flux map in experimental conditions, we applied nonstationary 13C metabolic flux analysis as a complementing strategy to flux balance analysis. We found that the result reveals negligible photorespiratory fluxes and a metabolically low active tricarboxylic acid cycle in phototrophic C. protothecoides. In comparison, high throughput of amphibolic reactions and the tricarboxylic acid cycle with no glyoxylate shunt activities were measured for heterotrophic cells. Lastly, taken together, the metabolic network modeling assisted

  1. Genome-based metabolic mapping and 13C flux analysis reveal systematic properties of an oleaginous microalga Chlorella protothecoides.

    PubMed

    Wu, Chao; Xiong, Wei; Dai, Junbiao; Wu, Qingyu

    2015-02-01

    Integrated and genome-based flux balance analysis, metabolomics, and (13)C-label profiling of phototrophic and heterotrophic metabolism in Chlorella protothecoides, an oleaginous green alga for biofuel. The green alga Chlorella protothecoides, capable of autotrophic and heterotrophic growth with rapid lipid synthesis, is a promising candidate for biofuel production. Based on the newly available genome knowledge of the alga, we reconstructed the compartmentalized metabolic network consisting of 272 metabolic reactions, 270 enzymes, and 461 encoding genes and simulated the growth in different cultivation conditions with flux balance analysis. Phenotype-phase plane analysis shows conditions achieving theoretical maximum of the biomass and corresponding fatty acid-producing rate for phototrophic cells (the ratio of photon uptake rate to CO2 uptake rate equals 8.4) and heterotrophic ones (the glucose uptake rate to O2 consumption rate reaches 2.4), respectively. Isotope-assisted liquid chromatography-mass spectrometry/mass spectrometry reveals higher metabolite concentrations in the glycolytic pathway and the tricarboxylic acid cycle in heterotrophic cells compared with autotrophic cells. We also observed enhanced levels of ATP, nicotinamide adenine dinucleotide (phosphate), reduced, acetyl-Coenzyme A, and malonyl-Coenzyme A in heterotrophic cells consistently, consistent with a strong activity of lipid synthesis. To profile the flux map in experimental conditions, we applied nonstationary (13)C metabolic flux analysis as a complementing strategy to flux balance analysis. The result reveals negligible photorespiratory fluxes and a metabolically low active tricarboxylic acid cycle in phototrophic C. protothecoides. In comparison, high throughput of amphibolic reactions and the tricarboxylic acid cycle with no glyoxylate shunt activities were measured for heterotrophic cells. Taken together, the metabolic network modeling assisted by experimental metabolomics and (13)C

  2. Complexation of oxygen ligands with dimeric rhodium(II) tetrakistrifluoroacetate in chloroform: 1H, 13C NMR and DFT studies

    NASA Astrophysics Data System (ADS)

    Głaszczka, Rafał; Jaźwiński, Jarosław

    2013-03-01

    The complexation of dimeric rhodium(II) tetrakistrifluoroacetylate with 25 ligands containing oxygen atoms: alcohols, ethers, ketones, aldehydes, carboxylic acids and esters in chloroform solution have been investigated by 1H and 13C NMR spectroscopy and Density Functional Theory (DFT) methods. Investigated ligands form 1:1 adducts in our experimental conditions, with stability constants in the order of several hundred mol-1. The exchange of ligands in solution is fast on the NMR spectroscopic timescale. The decrease of longitudinal relaxation times T1 in ligands in the presence of rhodium salt has been tested as the means of determination of the complexation site in ligands. The influence of complexation on chemical shifts in ligands was evaluated by a parameter complexation shift Δδ (Δδ = δadd - δlig). These parameters were positive (>0 ppm) and did not exceed 1 ppm for 1H NMR; and varied from ca. -5 to +15 ppm in the case of 13C NMR. The calculation by DFT methods using the B3LYP functional (structure optimization, electronic energy) and B3PW91 functional (shielding), and combinations of the (6-31G(2d), 6-311G++(2d,p), and LANL2DZ basis sets, followed by scaling procedures reproduced satisfactorily 1H and 13C chemical shifts and, with some limitations, allowed to estimate Δδ parameters.

  3. Conformation of gramicidin A channel in phospholipid vesicles: a 13C and 19F nuclear magnetic resonance study.

    PubMed Central

    Weinstein, S; Wallace, B A; Blout, E R; Morrow, J S; Veatch, W

    1979-01-01

    We have determined the conformation of the channel-forming polypeptide antibiotic gramicidin A in phosphatidylcholine vesicles by using 13C and 19F NMR spectroscopy. The models previously proposed for the conformation of the dimer channel differ in the surface localization of the NH2 and COOH termini. We have incorporated specific 13C and 19F nuclei at both the NH2, and COOH termini of gramicidin and have used 13C and 19F chemical shifts and spin lattice relaxation time measurements to determine the accessibility of these labels to three paramagnetic NMR probes--two in aqueous solution and one attached to the phosphatidylcholine fatty acid chain9 all of our results indicate that the COOH terminus of gramicidin in the channel is located near the surface of the membrane and the NH2 terminus is buried deep within the lipid bilayer. These findings strongly favor an NH2-terminal to NH2-terminal helical dimer as the major conformation for the gramicidin channel in phosphatidylcholine vesicles. PMID:92025

  4. Biosynthetic preparation of L-(/sup 13/C)- and (/sup 15/N)glutamate by Brevibacterium flavum

    SciTech Connect

    Walker, T.E.; London, R.E.

    1987-01-01

    The biosynthesis of isotopically labeled L-glutamic acid by the microorganism Brevibacterium flavum was studied with a variety of carbon-13-enriched precursors. The purpose of this study was twofold: (i) to develop techniques for the efficient preparation of labeled L-glutamate with a variety of useful labeling patterns which can be used for other metabolic studies, and (ii) to better understand the metabolic events leading to label scrambling in these strains. B. flavum, which is used commercially for the production of monosodium glutamate, has the capability of utilizing glucose or acetate as a sole carbon source, and important criterion from the standpoint of developing labeling strategies. Unfortunately, singly labeled glucose precursors lead to excessive isotopic dilution which reduces their usefulness. Studies with (3-/sup 13/C)pyruvate indicate that this problem can in principle be overcome by using labeled three-carbon precursors; however, conditions could not be found which would lead to an acceptable yield of isotopically labeled L-glutamate. In contrast, (1-/sup 13/C)- or (2-/sup 13/C)acetate provides relatively inexpensive, readily available precursors for the production of selectively labeled, high enriched L-glutamate. The preparation of L-(/sup 15/N)glutamate from (/sup 15/N)ammonium sulfate was carried out and is a very effective labeling strategy. Analysis of the isotopic distribution in labeled glutamate provides details about the metabolic pathways in these interesting organisms.

  5. Effects of a glucokinase activator on hepatic intermediary metabolism: study with 13C-isotopomer-based metabolomics

    PubMed Central

    Nissim, Itzhak; Horyn, Oksana; Nissim, Ilana; Daikhin, Yevgeny; Wehrli, Suzanne L.; Yudkoff, Marc; Matschinsky, Franz M.

    2013-01-01

    GKAs (glucokinase activators) are promising agents for the therapy of Type 2 diabetes, but little is known about their effects on hepatic intermediary metabolism. We monitored the fate of 13C-labelled glucose in both a liver perfusion system and isolated hepatocytes. MS and NMR spectroscopy were deployed to measure isotopic enrichment. The results demonstrate that the stimulation of glycolysis by GKA led to numerous changes in hepatic metabolism: (i) augmented flux through the TCA (tricarboxylic acid) cycle, as evidenced by greater incorporation of 13C into the cycle (anaplerosis) and increased generation of 13C isotopomers of citrate, glutamate and aspartate (cataplerosis); (ii) lowering of hepatic [Pi] and elevated [ATP], denoting greater phosphorylation potential and energy state; (iii) stimulation of glycogen synthesis from glucose, but inhibition of glycogen synthesis from 3-carbon precursors; (iv) increased synthesis of N-acetylglutamate and consequently augmented ureagenesis; (v) increased synthesis of glutamine, alanine, serine and glycine; and (vi) increased production and outflow of lactate. The present study provides a deeper insight into the hepatic actions of GKAs and uncovers the potential benefits and risks of GKA for treatment of diabetes. GKA improved hepatic bioenergetics, ureagenesis and glycogenesis, but decreased gluconeogenesis with a potential risk of lactic acidosis and fatty liver. PMID:22448977

  6. Preferential formation of 13C- 18O bonds in carbonate minerals, estimated using first-principles lattice dynamics

    NASA Astrophysics Data System (ADS)

    Schauble, Edwin A.; Ghosh, Prosenjit; Eiler, John M.

    2006-05-01

    Equilibrium constants for internal isotopic exchange reactions of the type: Ca12C18O16O2+Ca13C16O3↔Ca13C18O16O2+Ca12C16O3 for individual CO 32- groups in the carbonate minerals calcite (CaCO 3), aragonite (CaCO 3), dolomite (CaMg(CO 3) 2), magnesite (MgCO 3), witherite (BaCO 3), and nahcolite (NaHCO 3) are calculated using first-principles lattice dynamics. Calculations rely on density functional perturbation theory (DFPT) with norm-conserving planewave pseudopotentials to determine the vibrational frequencies of isotopically substituted crystals. Our results predict an ˜0.4‰ excess of 13C18O16O22- groups in all studied carbonate minerals at room-temperature equilibrium, relative to what would be expected in a stochastic mixture of carbonate isotopologues with the same bulk 13C/ 12C, 18O/ 16O, and 17O/ 16O ratios. The amount of excess 13C18O16O22- decreases with increasing temperature of equilibration, from 0.5‰ at 0 °C to <0.1‰ at 300 °C, suggesting that measurements of multiply substituted isotopologues of carbonate could be used to infer temperatures of ancient carbonate mineral precipitation and alteration events, even where the δ 18O of coexisting fluids is uncertain. The predicted temperature sensitivity of the equilibrium constant is ˜0.003‰/°C at 25 °C. Estimated equilibrium constants for the formation of 13C18O16O22- are remarkably uniform for the variety of minerals studied, suggesting that temperature calibrations will also be applicable to carbonate minerals not studied here without greatly compromising accuracy. A related equilibrium constant for the reaction: Ca12C18O16O2+Ca12C17O16O2↔Ca12C18O17O16O+Ca12C16O3 in calcite indicates formation of 0.1‰ excess 12C 18O 17O 16O 2- at 25 °C. In a conventional phosphoric acid reaction of carbonate to form CO 2 for mass-spectrometric analysis, molecules derived from 13C18O16O22- dominate (˜96%) the mass 47 signal, and 12C 18O 17O 16O 2- contributes most of the remainder (3%). This suggests

  7. Investigate the Metabolic Reprogramming of Saccharomyces cerevisiae for Enhanced Resistance to Mixed Fermentation Inhibitors via 13C Metabolic Flux Analysis

    PubMed Central

    Guo, Weihua; Chen, Yingying; Wei, Na; Feng, Xueyang

    2016-01-01

    The fermentation inhibitors from the pretreatment of lignocellulosic materials, e.g., acetic acid and furfural, are notorious due to their negative effects on the cell growth and chemical production. However, the metabolic reprogramming of the cells under these stress conditions, especially metabolic response for resistance to mixed inhibitors, has not been systematically investigated and remains mysterious. Therefore, in this study, 13C metabolic flux analysis (13C-MFA), a powerful tool to elucidate the intracellular carbon flux distributions, has been applied to two Saccharomyces cerevisiae strains with different tolerances to the inhibitors under acetic acid, furfural, and mixed (i.e., acetic acid and furfural) stress conditions to unravel the key metabolic responses. By analyzing the intracellular carbon fluxes as well as the energy and cofactor utilization under different conditions, we uncovered varied metabolic responses to different inhibitors. Under acetate stress, ATP and NADH production was slightly impaired, while NADPH tended towards overproduction. Under furfural stress, ATP and cofactors (including both NADH and NADPH) tended to be overproduced. However, under dual-stress condition, production of ATP and cofactors was severely impaired due to synergistic stress caused by the simultaneous addition of two fermentation inhibitors. Such phenomenon indicated the pivotal role of the energy and cofactor utilization in resisting the mixed inhibitors of acetic acid and furfural. Based on the discoveries, valuable insights are provided to improve the tolerance of S. cerevisiae strain and further enhance lignocellulosic fermentation. PMID:27532329

  8. Investigate the Metabolic Reprogramming of Saccharomyces cerevisiae for Enhanced Resistance to Mixed Fermentation Inhibitors via 13C Metabolic Flux Analysis.

    PubMed

    Guo, Weihua; Chen, Yingying; Wei, Na; Feng, Xueyang

    2016-01-01

    The fermentation inhibitors from the pretreatment of lignocellulosic materials, e.g., acetic acid and furfural, are notorious due to their negative effects on the cell growth and chemical production. However, the metabolic reprogramming of the cells under these stress conditions, especially metabolic response for resistance to mixed inhibitors, has not been systematically investigated and remains mysterious. Therefore, in this study, 13C metabolic flux analysis (13C-MFA), a powerful tool to elucidate the intracellular carbon flux distributions, has been applied to two Saccharomyces cerevisiae strains with different tolerances to the inhibitors under acetic acid, furfural, and mixed (i.e., acetic acid and furfural) stress conditions to unravel the key metabolic responses. By analyzing the intracellular carbon fluxes as well as the energy and cofactor utilization under different conditions, we uncovered varied metabolic responses to different inhibitors. Under acetate stress, ATP and NADH production was slightly impaired, while NADPH tended towards overproduction. Under furfural stress, ATP and cofactors (including both NADH and NADPH) tended to be overproduced. However, under dual-stress condition, production of ATP and cofactors was severely impaired due to synergistic stress caused by the simultaneous addition of two fermentation inhibitors. Such phenomenon indicated the pivotal role of the energy and cofactor utilization in resisting the mixed inhibitors of acetic acid and furfural. Based on the discoveries, valuable insights are provided to improve the tolerance of S. cerevisiae strain and further enhance lignocellulosic fermentation. PMID:27532329

  9. 13C MRS studies of neuroenergetics and neurotransmitter cycling in humans

    PubMed Central

    Rothman, Douglas L.; De Feyter, Henk M.; de Graaf, Robin A.; Mason, Graeme F.; Behar, Kevin L.

    2011-01-01

    In the last 25 years 13C MRS has been established as the only non invasive method for measuring glutamate neurotransmission and cell specific neuroenergetics. Although technically and experimentally challenging 13C MRS has already provided important new information on the relationship between neuroenergetics and neuronal function, energy cost of brain function, the high neuronal activity in the resting brain state, and how neuroenergetics and neurotransmitter cycling are altered in neurological and psychiatric disease. In this paper the current state of 13C MRS as it is applied to study neuroenergetics and neurotransmitter cycling in humans is reviewed. The focus is predominantly on recent findings in humans regarding metabolic pathways, applications to clinical research, and the technical status of the method. Results from in vivo 13C MRS studies in animals are discussed from the standpoint of validation of MRS measurements of neuroenergetics and neurotransmitter cycling and where they have helped identify key questions to address in human research. Controversies concerning the relation of neuroenergetics and neurotransmitter cycling and factors impacting accurate determination of fluxes through mathematical modeling are addressed. We further touch upon different 13C labeled substrates used to study brain metabolism, before reviewing a number of human brain diseases studied using 13C MRS. Future technological developments are discussed that will help to overcome limitations of 13C MRS with special attention on recent developments in hyperpolarized 13C MRS. PMID:21882281

  10. Amorphous Fe72Cr8P13C7 Powder with High Corrosion Resistance

    NASA Astrophysics Data System (ADS)

    Cho, Kangjo; Hwang, Choll-Hong; Pak, Chang-Su; Ryeom, Yeong-Jo

    1982-07-01

    Amorphous Fe72Cr8P13C7 powder has been prepared by the spark erosion technique and its corrosion behavior investigated potentiodynamically. It is concluded that the powder prepared this way possesses a relatively high corrosion resistance, as does amorphous Fe72Cr8P13C7 ribbon prepared by rapid quenching.

  11. 13c-SUCROSE BREATH TEST TO DIFFERENTIATE CONGENITAL SUCRASE-ISOMALTASE DEFICIENCY FROM PANDISACCHARIDASE DEFICIENCY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction: A substrate-paired breath test using 13C-sucrose (S) and 13C-glucose (G) has been developed to assess congenital sucrase-isomaltase deficiency (CSID). The aim was to determine if CSID could be detected without duodenal enzyme assay. Methods: Two patients (1F:1M, aged 1 & 15 yrs) wi...

  12. Latitudinal Variation in δ13C derived from Terrestrial Plants during the Cretaceous

    NASA Astrophysics Data System (ADS)

    Strganac, C.; Jacobs, L. L.; Ferguson, K.; Macphee, R. D.; Fiorillo, A. R.; Hooker, J.; Nishida, Y.; Flemming, C.

    2010-12-01

    Modern plankton and terrestrial plants exhibit a gradient in δ13C with latitude. Although there are several reasons for δ13C variation in plants, modern latitudinal variation is correlated with environmental and climatic factors such as temperature. We present δ13C values derived from mid-Cretaceous terrestrial plant fossils in Texas at paleolatitude ~30 N and Australia at paleolatitude ~70 S that show an offset in δ13C values, suggesting a latitudinal gradient in δ13C in plants during the Cretaceous. This hypothesis was tested by new data from Antarctica at paleolatitude ~60 S and Alaska at paleolatitude ~70 N, and we compared these data to published carbon isotope records. The latitudinal variation in plant δ13C was on the order of 2‰ more negative at high latitudes, suggesting a shallower Cretaceous latitudinal gradient in plant δ13C than at present. The shallow gradient in plant δ13C during the Cretaceous correlates with a latitudinal temperature gradient that is also less than today.

  13. Natural (13) C distribution in oil palm (Elaeis guineensis Jacq.) and consequences for allocation pattern.

    PubMed

    Lamade, Emmanuelle; Tcherkez, Guillaume; Darlan, Nuzul Hijri; Rodrigues, Rosario Lobato; Fresneau, Chantal; Mauve, Caroline; Lamothe-Sibold, Marlène; Sketriené, Diana; Ghashghaie, Jaleh

    2016-01-01

    Oil palm has now become one of the most important crops, palm oil representing nearly 25% of global plant oil consumption. Many studies have thus addressed oil palm ecophysiology and photosynthesis-based models of carbon allocation have been used. However, there is a lack of experimental data on carbon fixation and redistribution within palm trees, and important C-sinks have not been fully characterized yet. Here, we carried out extensive measurement of natural (13) C-abundance (δ(13) C) in oil palm tissues, including fruits at different maturation stages. We find a (13) C-enrichment in heterotrophic organs compared to mature leaves, with roots being the most (13) C-enriched. The δ(13) C in fruits decreased during maturation, reflecting the accumulation in (13) C-depleted lipids. We further used observed δ(13) C values to compute plausible carbon fluxes using a steady-state model of (13) C-distribution including metabolic isotope effects ((12) v/(13) v). The results suggest that fruits represent a major respiratory loss (≈39% of total tree respiration) and that sink organs such as fruits are fed by sucrose from leaves. That is, glucose appears to be a quantitatively important compound in palm tissues, but computations indicate that it is involved in dynamic starch metabolism rather that C-exchange between organs. PMID:26228944

  14. Variation in woody plant delta(13)C along a topoedaphic gradient in a subtropical savanna parkland.

    PubMed

    Bai, Edith; Boutton, Thomas W; Liu, Feng; Wu, X Ben; Archer, Steven R

    2008-06-01

    delta(13)C values of C(3) plants are indicators of plant carbon-water relations that integrate plant responses to environmental conditions. However, few studies have quantified spatial variation in plant delta(13)C at the landscape scale. We determined variation in leaf delta(13)C, leaf nitrogen per leaf area (N(area)), and specific leaf area (SLA) in April and August 2005 for all individuals of three common woody species within a 308 x 12-m belt transect spanning an upland-lowland topoedaphic gradient in a subtropical savanna in southern Texas. Clay content, available soil moisture, and soil total N were all negatively correlated with elevation. The delta(13)C values of Prosopis glandulosa (deciduous N(2)-fixing tree legume), Condalia hookeri (evergreen shrub), and Zanthoxylum fagara (evergreen shrub) leaves increased 1-4 per thousand with decreasing elevation, with the delta(13)C value of P. glandulosa leaves being 1-3 per thousand higher than those of the two shrub species. Contrary to theory and results from previous studies, delta(13)C values were highest where soil water was most available, suggesting that some other variable was overriding or interacting with water availability. Leaf N(area) was positively correlated with leaf delta(13)C of all species (p < 0.01) and appeared to exert the strongest control over delta(13)C along this topoedaphic gradient. Since leaf N(area) is positively related to photosynthetic capacity, plants with high leaf N(area) are likely to have low p (I)/p (a) ratios and therefore higher delta(13)C values, assuming stomatal conductance is constant. Specific leaf area was not correlated significantly with leaf delta(13)C. Following a progressive growing season drought in July/August, leaf delta(13)C decreased. The lower delta(13)C in August may reflect the accumulation of (13)C-depleted epicuticular leaf wax. We suggest control of leaf delta(13)C along this topoedaphic gradient is mediated by leaf N(area) rather than by stomatal

  15. A 13C-NMR study of exopolysaccharide synthesis in Rhizobium meliloti Su47 strain

    NASA Astrophysics Data System (ADS)

    Tavernier, P.; Portais, J.-C.; Besson, I.; Courtois, J.; Courtois, B.; Barbotin, J.-N.

    1998-02-01

    Metabolic pathways implied in the synthesis of succinoglycan produced by the Su47 strain of R. meliloti were evaluated by 13C-NMR spectroscopy after incubation with [1{-}13C] or [2{-}13C] glucose. The biosynthesis of this polymer by R. meliloti from glucose occurred by a direct polymerisation of the introduced glucose and by the pentose phosphate pathway. Les voies métaboliques impliquées dans la synthèse du succinoglycane produit par la souche Su47 de R. meliloti ont été évaluées par la spectroscopie de RMN du carbone 13 après incubation des cellules avec du [1{-}13C] ou [2{-}13C] glucose. La biosynthèse de ce polymère à partir du glucose se produit par polymérisation directe du glucose et par la voie des pentoses phosphate.

  16. Fish Movement and Dietary History Derived from Otolith (delta)13C

    SciTech Connect

    Weber, P K; Finlay, J C; Power, M E; Phillis, C C; Ramon, C E; Eaton, G F; Ingram, B L

    2005-09-08

    Habitat use and food web linkages are critical data for fish conservation and habitat restoration efforts, particularly for threatened salmonids species. Otolith microchemistry has been shown to be a powerful tool for reconstructing fish movement, but over small distances (kilometers), geology-derived differences in otolith chemistry are rare. Here, we demonstrate that otolith {sup 13}C/{sup 12}C ratio (i.e. {delta}{sup 13}C) of anadromous steelhead trout can be used to distinguish residence in small streams from residence in larger streams and rivers. While previous research has shown that water dissolved inorganic carbon {delta}{sup 13}C is the primary source of carbon in otoliths, the downstream change in food {delta}{sup 13}C in this watershed appears to be the primary control on otolith {delta}{sup 13}C. As a result, this method can also be applied to the problem of reconstructing feeding history at a location.

  17. Fish movement and dietary history derived from otolith δ13C

    NASA Astrophysics Data System (ADS)

    Weber, P. K.; Finlay, J. C.; Power, M. E.; Phillis, C. C.; Ramon, C. E.; Eaton, G. F.; Ingram, B. L.

    2005-12-01

    Habitat use and food web linkages are critical data for fish conservation and habitat restoration efforts, particularly for threatened salmonids species. Otolith microchemistry has been shown to be a powerful tool for reconstructing fish movement, but over small distances (kilometers), geology-derived differences in otolith chemistry are rare. Here, we demonstrate that otolith 13C/12C ratio (i.e. δ13C) of anadromous steelhead trout can be used to distinguish residence in small streams from residence in larger streams and rivers. While previous research has shown that water dissolved inorganic carbon d13C is the primary source of carbon in otoliths, the downstream change in food δ13C in this watershed appears to be the primary control on otolith δ13C. As a result, this method can also be applied to the problem of reconstructing feeding history at a location.

  18. Continuous Flow - Cavity RingDown Spectroscopy Using a Novel Universal Interface for High-Precision Bulk 13C Analysis

    NASA Astrophysics Data System (ADS)

    Saad, Nabil; Richman, Bruce

    2010-05-01

    We have developed the world's first optical spectroscopy-based system for bulk stable isotope analysis of 13C. The system is based on a novel universal interface, named LIAISON, capable of coupling to almost any CO2-generating sample preparation front-end ranging from an elemental analyzer to any dissolved carbon analysis module, which are of significant use in geochemical, ecological and food authentication studies. In one specific application, we have coupled LIAISON to an elemental analyzer (EA) and to a cavity ring-down spectrometer (CRDS) for 13C isotopic analysis of adulterated honey samples. Another application was developed to analyze dissolved inorganic carbon in water samples. LIAISON is suited for handling a high-throughput sample analysis process by running three different gas handling operations in parallel: Admitting combustion gas from the EA into a first gas bellows, analyzing the previous sample collected into a second gas bellows with CRDS, and flushing and purging a third gas bellows in preparation for the upcoming sample collection operation. The sample-to-sample analysis time is 10 minutes and the operation is completely automated for the whole front-end auto-sampler tray capacity, requiring no operator intervention. The CRDS data are collected, tabulated and saved into an output text file. The memory effect between the USGS L-Glutamic acid standard at natural abundance and the moderately enriched USGS L-Glutamic acid standard is excluded by the selection of the adequate number and duration of flush and purge cycles of the gas sample bags. The system's proven accuracy was cross-checked with EA-IRMS and its achieved precision was typically less than 0.2 permil, including the 13C-enriched tested samples. The LIAISON-CRDS system presented here provides a fully automated solution for 13C bulk stable isotope analysis with unprecedented ease-of-use and possible field portability and application with the availability of a compact front-end. In

  19. Microbial 13C utilization patterns via stable isotope probing of phospholipid biomarkers in Mojave Desert soils exposed to ambient and elevated atmospheric CO2

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Changes in plant inputs under changing atmospheric CO2 can be expected to alter the size and/or composition of active soil microbial communities which determine whether soils are a C sink or source. Autotrophically-fixed 13C was traced into phospholipid fatty acid (PLFA) biomarkers in Mojave Desert...

  20. Evidence of 13C non-covalent isotope effects obtained by quantitative 13C nuclear magnetic resonance spectroscopy at natural abundance during normal phase liquid chromatography.

    PubMed

    Botosoa, Eliot P; Silvestre, Virginie; Robins, Richard J; Rojas, Jose Manuel Moreno; Guillou, Claude; Remaud, Gérald S

    2009-10-16

    Quantitative isotopic (13)C NMR at natural abundance has been used to determine the site-by-site (13)C/(12)C ratios in vanillin and a number of related compounds eluted from silica gel chromatography columns under similar conditions. Head-to-tail isotope fractionation is observed in all compounds at the majority of carbon positions. Furthermore, the site-specific isotope deviations show signatures characteristic of the position and functionality of the substituents present. The observed effects are more complex than would be obtained by simply summing the individual effects. Such detail is hidden when only the global (13)C content is measured by mass spectrometry. In particular, carbon positions within the aromatic ring are found to show site-specific isotope fractionation between the solute and the stationary phase. These interactions, defined as non-covalent isotope effects, can be normal or inverse and vary with the substitution pattern present. PMID:19748628

  1. Dynamic nuclear polarization-enhanced 13C NMR spectroscopy of static biological solids

    PubMed Central

    Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2013-01-01

    We explore the possibility of using dynamic nuclear polarization (DNP) to enhance signals in structural studies of biological solids by solid state NMR without sample spinning. Specifically, we use 2D 13C-13C exchange spectroscopy to probe the peptide backbone torsion angles (ϕ,ψ) in a series of selectively 13C-labeled 40-residue β-amyloid (Aβ1–40) samples, in both fibrillar and non-fibrillar states. Experiments are carried out at 9.39 T and 8 K, using a static double-resonance NMR probe and low-power microwave irradiation at 264 GHz. In frozen solutions of Aβ1–40 fibrils doped with DOTOPA-TEMPO, we observe DNP signal enhancement factors of 16–21. We show that the orientation- and frequency-dependent spin polarization exchange between sequential backbone carbonyl 13C labels can be simulated accurately using a simple expression for the exchange rate, after experimentally determined homogeneous 13C lineshapes are incorporated in the simulations. The experimental 2D 13C-13C exchange spectra place constraints on the ϕ and ψ angles between the two carbonyl labels. Although the data are not sufficient to determine ϕ and ψ uniquely, the data do provide non-trivial constraints that could be included in structure calculations. With DNP at low temperatures, 2D 13C-13C exchange spectra can be obtained from a 3.5 mg sample of Aβ1–40 fibrils in 4 hr or less, despite the broad 13C chemical shift anisotropy line shapes that are observed in static samples. PMID:23562665

  2. Dynamic nuclear polarization-enhanced 13C NMR spectroscopy of static biological solids

    NASA Astrophysics Data System (ADS)

    Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2013-06-01

    We explore the possibility of using dynamic nuclear polarization (DNP) to enhance signals in structural studies of biological solids by solid state NMR without sample spinning. Specifically, we use 2D 13C-13C exchange spectroscopy to probe the peptide backbone torsion angles (ϕ, ψ) in a series of selectively 13C-labeled 40-residue β-amyloid (Aβ1-40) samples, in both fibrillar and non-fibrillar states. Experiments are carried out at 9.39 T and 8 K, using a static double-resonance NMR probe and low-power microwave irradiation at 264 GHz. In frozen solutions of Aβ1-40 fibrils doped with DOTOPA-TEMPO, we observe DNP signal enhancement factors of 16-21. We show that the orientation- and frequency-dependent spin polarization exchange between sequential backbone carbonyl 13C labels can be simulated accurately using a simple expression for the exchange rate, after experimentally determined homogeneous 13C lineshapes are incorporated in the simulations. The experimental 2D 13C-13C exchange spectra place constraints on the ϕ and ψ angles between the two carbonyl labels. Although the data are not sufficient to determine ϕ and ψ uniquely, the data do provide non-trivial constraints that could be included in structure calculations. With DNP at low temperatures, 2D 13C-13C exchange spectra can be obtained from a 3.5 mg sample of Aβ1-40 fibrils in 4 h or less, despite the broad 13C chemical shift anisotropy line shapes that are observed in static samples.

  3. Microbial transformations of free versus sorbed alanine analyzed by position-specific 13C and 14C labeling and 13C-PLFA analysis

    NASA Astrophysics Data System (ADS)

    Apostel, Carolin; Dippold, Michaela; Bore, Ezekiel; Kuzyakov, Yakov

    2015-04-01

    Sorption of charged or partially charged low molecular weight organic substances (LMWOS) to soil mineral surfaces delays microbial uptake and therefore mineralization of LMWOS to CO2, as well as all other biochemical transformations. We used position-specific labeling, a tool of isotope applications novel to soil sciences, to compare the transformation mechanisms of sorbed and non-sorbed alanine in soil. Alanine as an amino acid links C- and N-cycles in soil and therefore is a model representative for the pool of LMWOS. To assess transformations of sorbed alanine, we combined position-specifically and uniformly 13C and 14C labeled alanine tracer solution with a loamy haplic luvisol that had previously been sterilized by γ-radiation. After shaking the mixtures, the supernatant was removed, as was all non-sorbed alanine by repeated shaking with millipore water. The labeled soil was added to non-sterilized soil from the same site. To compare the effect of sorption, soil labeled with the same position-specifically labeled tracers without previous sorption was prepared and incubated as well. We captured the respired CO2 and determined its 14C-activity at increasing time steps. The incorporation of 14C into microbial biomass was determined by CFE, and utilization of individual C positions by distinct microbial groups was evaluated by 13C-PLFA analysis. A dual peak in the respired CO2 revealed the influence of two sorption mechanisms. Microbial uptake and transformation of the sorbed alanine was 3 times slower compared to non-sorbed alanine. To compare the fate of individual C atoms independent of their concentration and pool size in soil, we introduced the divergence index (DI). The DI reveals the convergent or divergent behaviour of C from individual molecule positions during microbial utilization. The DI revealed, that alanines C-1 position was mainly oxidized to CO2, while its C-2 and C-3 were preferentially incorporated in microbial biomass and PLFAs. This indicates

  4. Global Fold of Human Cannabinoid Type 2 Receptor Probed by Solid-State 13C-, 15N-MAS NMR and Molecular Dynamics Simulations

    PubMed Central

    Kimura, Tomohiro; Vukoti, Krishna; Lynch, Diane L.; Hurst, Dow P.; Grossfield, Alan; Pitman, Michael C.; Reggio, Patricia H.; Yeliseev, Alexei A.; Gawrisch, Klaus

    2014-01-01

    The global fold of human cannabinoid type 2 (CB2) receptor in the agonist-bound active state in lipid bilayers was investigated by solid-state 13C- and 15N magic-angle spinning (MAS) NMR, in combination with chemical-shift prediction from a structural model of the receptor obtained by microsecond-long molecular dynamics (MD) simulations. Uniformly 13C-, and 15N-labeled CB2 receptor was expressed in milligram quantities by bacterial fermentation, purified, and functionally reconstituted into liposomes. 13C MAS NMR spectra were recorded without sensitivity enhancement for direct comparison of Cα, Cβ, and C=O bands of superimposed resonances with predictions from protein structures generated by MD. The experimental NMR spectra matched the calculated spectra reasonably well indicating agreement of the global fold of the protein between experiment and simulations. In particular, the 13C chemical shift distribution of Cα resonances was shown to be very sensitive to both the primary amino acid sequence and the secondary structure of CB2. Thus the shape of the Cα band can be used as an indicator of CB2 global fold. The prediction from MD simulations indicated that upon receptor activation a rather limited number of amino acid residues, mainly located in the extracellular loop 2 and the second half of intracellular loop 3, change their chemical shifts significantly (≥1.5 ppm for carbons and ≥5.0 ppm for nitrogens). Simulated two-dimensional 13Cα(i)-13C=O(i) and 13C=O(i)-15NH(i+1) dipolar-interaction correlation spectra provide guidance for selective amino-acid labeling and signal assignment schemes to study the molecular mechanism of activation of CB2 by solid-state MAS NMR. PMID:23999926

  5. Bonded Cumomer Analysis of Human Melanoma Metabolism Monitored by 13C NMR Spectroscopy of Perfused Tumor Cells.

    PubMed

    Shestov, Alexander A; Mancuso, Anthony; Lee, Seung-Cheol; Guo, Lili; Nelson, David S; Roman, Jeffrey C; Henry, Pierre-Gilles; Leeper, Dennis B; Blair, Ian A; Glickson, Jerry D

    2016-03-01

    A network model for the determination of tumor metabolic fluxes from (13)C NMR kinetic isotopomer data has been developed and validated with perfused human DB-1 melanoma cells carrying the BRAF V600E mutation, which promotes oxidative metabolism. The model generated in the bonded cumomer formalism describes key pathways of tumor intermediary metabolism and yields dynamic curves for positional isotopic enrichment and spin-spin multiplets. Cells attached to microcarrier beads were perfused with 26 mm [1,6-(13)C2]glucose under normoxic conditions at 37 °C and monitored by (13)C NMR spectroscopy. Excellent agreement between model-predicted and experimentally measured values of the rates of oxygen and glucose consumption, lactate production, and glutamate pool size validated the model. ATP production by glycolytic and oxidative metabolism were compared under hyperglycemic normoxic conditions; 51% of the energy came from oxidative phosphorylation and 49% came from glycolysis. Even though the rate of glutamine uptake was ∼ 50% of the tricarboxylic acid cycle flux, the rate of ATP production from glutamine was essentially zero (no glutaminolysis). De novo fatty acid production was ∼ 6% of the tricarboxylic acid cycle flux. The oxidative pentose phosphate pathway flux was 3.6% of glycolysis, and three non-oxidative pentose phosphate pathway exchange fluxes were calculated. Mass spectrometry was then used to compare fluxes through various pathways under hyperglycemic (26 mm) and euglycemic (5 mm) conditions. Under euglycemic conditions glutamine uptake doubled, but ATP production from glutamine did not significantly change. A new parameter measuring the Warburg effect (the ratio of lactate production flux to pyruvate influx through the mitochondrial pyruvate carrier) was calculated to be 21, close to upper limit of oxidative metabolism. PMID:26703469

  6. Biosynthesis of pyrroloquinoline quinone. 1. Identification of biosynthetic precursors using /sup 13/C labeling and NMR spectroscopy

    SciTech Connect

    Houck, D.R.; Hanners, J.L.; Unkefer, C.J.

    1988-09-28

    The biosynthesis of pyrroloquinoline quinone (PQQ) in the methylotropic bacterium methylobacterium AM1 has been investigated using /sup 13/C-labelling of the products and NMR spectroscopy. The data indicated that the quinoline portion of PQQ is formed by a novel condensation of N-1, C-2, -3, and -4 of glutamate with a symmetrical six-carbon ring derived from the shikimate pathway. It is postulated that tyrosine is the shikimate-derived percursor, since pyrrole could be formed by the internal cyclization of the amino acid backbone. 18 references, 2 figures, 2 tables.

  7. Continuous-flow 13C-filtered 1H NMR spectroscopy of ethanol metabolism in rat liver perfusate.

    PubMed

    Albert, K; Sudmeier, J L; Anwer, M S; Bachovchin, W W

    1989-09-01

    Using a 188.5-microliters continuous-flow dual probe 1H[13C] spin-echo difference spectra of rat liver perfusate were acquired. The conversion of [1-13C]ethanol to [1-13C]-acetaldehyde was readily monitored as a function of time. In combination with 1-1 water nonexcitation and WALTZ 13C decoupling, this method proved to be superior in sensitivity and selectivity to direct 1H or 13C detection. PMID:2779419

  8. VizieR Online Data Catalog: Doubly 13C-substituted ethyl cyanide (Margules+,

    NASA Astrophysics Data System (ADS)

    Margules, L.; Belloche, A.; Muller, H. S. P.; Motiyenko, R. A.; Guillemin, J.-C.; Garrod, R. T.; Menten, K. M.

    2016-04-01

    We identified more than 5000 rotational transitions, pertaining to more than 3500 different transition frequencies, in the laboratory for each of the three doubly 13C-substituted isotopomers. The quantum numbers reach J~115 and Ka~35, resulting in accurate spectroscopic parameters and accurate rest frequency calculations beyond 1000 GHz for strong to moderately weak transitions of either isotopomer. All three species are unambiguously detected in our ALMA data. The 12C/13C column density ratio of the isotopomers with one 13C atom to those with two 13C atoms is about 25. Ethyl cyanide is the second molecule after methyl cyanide for which isotopologues containing two 13C atoms have been securely detected in the interstellar medium. The model of our ethyl cyanide data suggests that we should be able to detect vibrational satellites of the main species up to at least v19=1 at 1130K and up to v13+v21=2 at 600K for the isotopologues with one 13C atom in our present ALMA data. Such satellites may be too weak to be identified unambiguously for isotopologues with two 13C atoms. (3 data files).

  9. Simultaneous imaging of 13C metabolism and 1H structure: technical considerations and potential applications.

    PubMed

    Gordon, Jeremy W; Fain, Sean B; Niles, David J; Ludwig, Kai D; Johnson, Kevin M; Peterson, Eric T

    2015-05-01

    Real-time imaging of (13)C metabolism in vivo has been enabled by recent advances in hyperpolarization. As a result of the inherently low natural abundance of endogenous (13)C nuclei, hyperpolarized (13)C images lack structural information that could be used to aid in motion detection and anatomical registration. Motion before or during the (13)C acquisition can therefore result in artifacts and misregistration that may obscure measures of metabolism. In this work, we demonstrate a method to simultaneously image both (1)H and (13)C nuclei using a dual-nucleus spectral-spatial radiofrequency excitation and a fully coincident readout for rapid multinuclear spectroscopic imaging. With the appropriate multinuclear hardware, and the means to simultaneously excite and receive on both channels, this technique is straightforward to implement requiring little to no increase in scan time. Phantom and in vivo experiments were performed with both Cartesian and spiral trajectories to validate and illustrate the utility of simultaneous acquisitions. Motion compensation of dynamic metabolic measurements acquired during free breathing was demonstrated using motion tracking derived from (1)H data. Simultaneous multinuclear imaging provides structural (1)H and metabolic (13)C images that are correlated both spatially and temporally, and are therefore amenable to joint (1)H and (13)C analysis and correction of structure-function images. PMID:25810146

  10. 13C-NMR study of labeled vinyl groups in paramagnetic myoglobin derivatives.

    PubMed

    Sankar, S S; La Mar, G N; Smith, K M; Fujinari, E M

    1987-04-01

    The 13C-NMR spectra of high-spin met-aquo myoglobin, spin-equilibrium met-azido myoglobin, low-spin met-cyano myoglobin, deoxy myoglobin and carbonmonoxy myoglobin from sperm whale reconstituted with hemin 13C enriched at both vinyl alpha or beta positions have been recorded. In all cases the labeled vinyl 13C signals are clearly resolved and useful spectra could be obtained within approx. 15 minutes. The decoupling of multiplet structure due to attached proton(s) has led to the specific assignment of vinyl 13C alpha signals in all paramagnetic derivatives and the 13C beta signals in met-cyano myoglobin. In all other cases, the collapse of the proton multiplet structure as a function of 1H decoupling frequency has located, but not assigned, the attached 1H resonance positions which are obscured by the intense diamagnetic envelope in the 1H-NMR spectrum. The resulting vinyl 13C hyperfine shifts follow Curie behavior, and the patterns closely resemble those in the appropriate model complexes in the same oxidation/spin/ligation state, except that the protein exhibits more in-plane asymmetry. The hyperfine shift patterns are indicative of dominant pi contact shifts for all ferric complexes. Deoxy myoglobin vinyl 13C and 1H contact shifts provide little evidence for pi bonding. PMID:3828362

  11. Dephosphorylation and biodistribution of 1-13C-phospholactate in vivo†

    PubMed Central

    Shchepin, Roman V.; Pham, Wellington; Chekmenev, Eduard Y.

    2015-01-01

    Here, we present a new approach for the delivery of a metabolic contrast agent for in vivo molecular imaging. The use of a phosphate-protecting group that facilitates parahydrogen-induced polarization of 1-13C-phospholactate potentially enables the in vivo administration of a hydrogenated hyperpolarized adduct. When injected, nonhyperpolarized 1-13C-phospholactate is retained in the vasculature during its metabolic conversion to 1-13C-lactate by blood phosphatases as demonstrated here using a mucin 1 mouse model of breast cancer and ex vivo high-resolution 13C NMR. This multisecond process is a suitable mechanism for the delivery of relatively short-lived 13C and potentially 15N hyperpolarized contrast agents using –OH phosphorylated small molecules, which is demonstrated here for the first time as an example of 1-13C-phospholactate. Through this approach, DL-1-13C-lactate is taken up by tissues and organs including the liver, kidneys, brain, heart, and tumors according to a timescale amenable to hyperpolarized magnetic resonance imaging. PMID:24995802

  12. Norlittorine and norhyoscyamine identified as products of littorine and hyoscyamine metabolism by (13)C-labeling in Datura innoxia hairy roots.

    PubMed

    Al Balkhi, Mohamad Houssam; Schiltz, Séverine; Lesur, David; Lanoue, Arnaud; Wadouachi, Anne; Boitel-Conti, Michèle

    2012-02-01

    The presence of two compounds, norlittorine and norhyoscyamine, has been reported in leaves and roots of Datura innoxia; however their metabolic origin in the tropane alkaloid pathway has remained unknown. Precise knowledge of this pathway is a necessary pre-requisite to optimize the production of hyoscyamine and scopolamine in D. innoxia hairy root cultures. The exact structure of norlittorine and norhyoscyamine was confirmed by LC-MS/MS and NMR analyses. Isotopic labeling experiments, using [1-(13)C]-phenylalanine, [1'-(13)C]-littorine and [1'-(13)C]-hyoscyamine, combined with elicitor treatments, using methyl jasmonate, coronalon and 1-aminocyclopropane-1-carboxylic acid, were used to investigate the metabolic origin of the N-demethylated tropane alkaloids. The results suggest that norlittorine and norhyoscyamine are induced under stress conditions by conversion of littorine and hyoscyamine. We propose the N-demethylation of tropane alkaloids as a mechanism to detoxify cells in overproducing conditions. PMID:22083085

  13. (13)C-NMR-Based Metabolomic Profiling of Typical Asian Soy Sauces.

    PubMed

    Kamal, Ghulam Mustafa; Yuan, Bin; Hussain, Abdullah Ijaz; Wang, Jie; Jiang, Bin; Zhang, Xu; Liu, Maili

    2016-01-01

    It has been a strong consumer interest to choose high quality food products with clear information about their origin and composition. In the present study, a total of 22 Asian soy sauce samples have been analyzed in terms of (13)C-NMR spectroscopy. Spectral data were analyzed by multivariate statistical methods in order to find out the important metabolites causing the discrimination among typical soy sauces from different Asian regions. It was found that significantly higher concentrations of glutamate in Chinese red cooking (CR) soy sauce may be the result of the manual addition of monosodium glutamate (MSG) in the final soy sauce product. Whereas lower concentrations of amino acids, like leucine, isoleucine and valine, observed in CR indicate the different fermentation period used in production of CR soy sauce, on the other hand, the concentration of some fermentation cycle metabolites, such as acetate and sucrose, can be divided into two groups. The concentrations of these fermentation cycle metabolites were lower in CR and Singapore Kikkoman (SK), whereas much higher in Japanese shoyu (JS) and Taiwan (China) light (TL), which depict the influence of climatic conditions. Therefore, the results of our study directly indicate the influences of traditional ways of fermentation, climatic conditions and the selection of raw materials and can be helpful for consumers to choose their desired soy sauce products, as well as for researchers in further authentication studies about soy sauce. PMID:27598115

  14. The Extended Spectroscopic Database on Formamide: Parent, 13C and Deuterated Species up to 1 THz

    NASA Astrophysics Data System (ADS)

    Kutsenko, A. S.; Motiyenko, R. A.; Margulès, L.; Guillemin, J.-C.

    2011-06-01

    Formamide (NH_2CHO) is the simplest interstellar molecule containing a peptide bond that provides polymerization of amino acids. It is also considered as a precursor of acetamide - another molecule containing a peptide bond that has been recently discovered in interstellar medium. While the rotational spectra of the parent istopic species of formamide were extensively studied up to 500 GHz only few data are available on its deuterated species. We present the new study of the rotational spectra of all singly deuterated isotopologues of formamide as well as new analysis of the rotational spectra of the parent and 13C isotopic species of formamide in the frequency range up to 1 THz. All the measurements have been performed using the Lille spectrometer based on the solid state sources. In total, about 2500 newly measured transition frequencies have been added to existing dataset on the rotational spectra of formamide and its isotopologues. This work is supported by ANR-08-BLAN-0225, the french Programme National de Physique Chimie du Milieu Interstellaire. A.K. would like to acknowledge the support of the Embassy of France in Ukraine. Hollis, J.M. et al. Astrophys. J. Letters 643 (2006) L25. Kryvda, A.V. et al. J. Mol. Spec. 254 (2009) 28.

  15. Toward using delta13C of ecosystem respiration to monitor canopy physiology in complex terrain.

    PubMed

    Pypker, T G; Hauck, M; Sulzman, E W; Unsworth, M H; Mix, A C; Kayler, Z; Conklin, D; Kennedy, A M; Barnard, H R; Phillips, C; Bond, B J

    2008-12-01

    In 2005 and 2006, air samples were collected at the base of a Douglas-fir watershed to monitor seasonal changes in the delta13CO2 of ecosystem respiration (delta13C(ER)). The goals of this study were to determine whether variations in delta13C(ER) correlated with environmental variables and could be used to predict expected variations in canopy-average stomatal conductance (Gs). Changes in delta13C(ER) correlated weakly with changes in vapor pressure deficit (VPD) measured 0 and 3-7 days earlier and significantly with soil matric potential (psi(m)) (P value <0.02) measured on the same day. Midday G (s) was estimated using sapflow measurements (heat-dissipation method) at four plots located at different elevations within the watershed. Values of midday Gs from 0 and 3-7 days earlier were correlated with delta13C(ER), with the 5-day lag being significant (P value <0.05). To examine direct relationships between delta13C(ER) and recent Gs, we used models relating isotope discrimination to stomatal conductance and photosynthetic capacity at the leaf level to estimate values of stomatal conductance ("Gs-I") that would be expected if respired CO2 were derived entirely from recent photosynthate. We compared these values with estimates of Gs using direct measurement of transpiration at multiple locations in the watershed. Considering that the approach based on isotopes considers only the effect of photosynthetic discrimination on delta13C(ER), the magnitude and range in the two values were surprisingly similar. We conclude that: (1) delta13C(ER) is sensitive to variations in weather, and (2) delta13C(ER) potentially could be used to directly monitor average, basin-wide variations in Gs in complex terrain if further research improves understanding of how delta13C(ER) is influenced by post-assimilation fractionation processes. PMID:18839214

  16. Quantification of 1-(13) C-L-methionine in rat serum with hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry and its application in pharmacokinetic study.

    PubMed

    Xu, Ying; Huang, Xiao; Nie, Xiuli; Yang, Li; Yan, Weili; Wang, Zhengtao; Wang, Changhong; Hu, Zhibi

    2011-09-01

    A rapid, selective and sensitive hydrophilic interaction liquid chromatography (HILIC) coupled with tandem mass spectrometry (MS/MS) method was developed to determine 1-(13) C-l-methionine in rat serum. Proteins in serum were precipitated using acetonitrile and the supernatant was separated after centrifugation. 1-(13) C-l-phenylalnine was used as the internal standard. HILIC-tandem mass spectrometry analysis was performed on a hydrophilic interaction silica column (TSK-GEL AMIDE-80) using a linear gradient elution system, acetonitrile-5 mm ammonium acetate containing 0.1% formic acid and multiple reaction monitoring mode for 1-(13) C-l-methionine and 1-(13) C-l-phenylalnine. The assay was validated with a linear range between 10 and 150 ng mL(-1) (r ≥ 0.99) and a lower limit of quantification of 10 ng mL(-1) , calculated with weighted (1/x(2) ) least squares linear regression. The RSD of intra-day precision was smaller than 3.6% and the inter-day RSD less than 6.5%, while the average recovery was 100.48% with an RSD of accuracy within 2.9%, determined from quality control samples. The HILIC-MS/MS method was fully validated and successfully applied to the in vivo pharmacokinetic study of stable-isotope 1-(13) C-l-methionine in rats. PMID:21287581

  17. Determination of the Orientation and Dynamics of Ergosterol in Model Membranes Using Uniform 13C Labeling and Dynamically Averaged 13C Chemical Shift Anisotropies as Experimental Restraints

    PubMed Central

    Soubias, O.; Jolibois, F.; Massou, S.; Milon, A.; Réat, V.

    2005-01-01

    A new strategy was established to determine the average orientation and dynamics of ergosterol in dimyristoylphosphatidylcholine model membranes. It is based on the analysis of chemical shift anisotropies (CSAs) averaged by the molecular dynamics. Static 13C CSA tensors were computed by quantum chemistry, using the gauge-including atomic-orbital approach within Hartree-Fock theory. Uniformly 13C-labeled ergosterol was purified from Pichia pastoris cells grown on labeled methanol. After reconstitution into dimyristoylphosphatidylcholine lipids, the complete 1H and 13C assignment of ergosterol's resonances was performed using a combination of magic-angle spinning two-dimensional experiments. Dynamically averaged CSAs were determined by standard side-band intensity analysis for isolated 13C resonances (C3 and ethylenic carbons) and by off-magic-angle spinning experiments for other carbons. A set of 18 constraints was thus obtained, from which the sterol's molecular order parameter and average orientation could be precisely defined. The validity of using computed CSAs in this strategy was verified on cholesterol model systems. This new method allowed us to quantify ergosterol's dynamics at three molar ratios: 16 mol % (Ld phase), 30 mol % (Lo phase), and 23 mol % (mixed phases). Contrary to cholesterol, ergosterol's molecular diffusion axis makes an important angle (14°) with the inertial axis of the rigid four-ring system. PMID:15923221

  18. Position-Specific Isotope Analysis of Xanthines: A (13)C Nuclear Magnetic Resonance Method to Determine the (13)C Intramolecular Composition at Natural Abundance.

    PubMed

    Diomande, Didier G; Martineau, Estelle; Gilbert, Alexis; Nun, Pierrick; Murata, Ariaki; Yamada, Keita; Watanabe, Naoharu; Tea, Illa; Robins, Richard J; Yoshida, Naohiro; Remaud, Gérald S

    2015-07-01

    The natural xanthines caffeine, theobromine, and theophylline are of major commercial importance as flavor constituents in coffee, cocoa, tea, and a number of other beverages. However, their exploitation for authenticity, a requirement in these commodities that have a large origin-based price-range, by the standard method of isotope ratio monitoring by mass spectrometry (irm-MS) is limited. We have now developed a methodology that overcomes this deficit that exploits the power of isotopic quantitative (13)C nuclear magnetic resonance (NMR) spectrometry combined with chemical modification of the xanthines to enable the determination of positional intramolecular (13)C/(12)C ratios (δ(13)Ci) with high precision. However, only caffeine is amenable to analysis: theobromine and theophylline present substantial difficulties due to their poor solubility. However, their N-methylation to caffeine makes spectral acquisition feasible. The method is confirmed as robust, with good repeatability of the δ(13)Ci values in caffeine appropriate for isotope fractionation measurements at natural abundance. It is shown that there is negligible isotope fractionation during the chemical N-methylation procedure. Thus, the method preserves the original positional δ(13)Ci values. The method has been applied to measure the position-specific variation of the (13)C/(12)C distribution in caffeine. Not only is a clear difference between caffeine isolated from different sources observed, but theobromine from cocoa is found to show a (13)C pattern distinct from that of caffeine. PMID:26067163

  19. Comprehensive signal assignment of 13C-labeled lignocellulose using multidimensional solution NMR and 13C chemical shift comparison with solid-state NMR.

    PubMed

    Komatsu, Takanori; Kikuchi, Jun

    2013-09-17

    A multidimensional solution NMR method has been developed using various pulse programs including HCCH-COSY and (13)C-HSQC-NOESY for the structural characterization of commercially available (13)C labeled lignocellulose from potatoes (Solanum tuberosum L.), chicory (Cichorium intybus), and corn (Zea mays). This new method allowed for 119 of the signals in the (13)C-HSQC spectrum of lignocelluloses to be assigned and was successfully used to characterize the structures of lignocellulose samples from three plants in terms of their xylan and xyloglucan structures, which are the major hemicelluloses in angiosperm. Furthermore, this new method provided greater insight into fine structures of lignin by providing a high resolution to the aromatic signals of the β-aryl ether and resinol moieties, as well as the diastereomeric signals of the β-aryl ether. Finally, the (13)C chemical shifts assigned in this study were compared with those from solid-state NMR and indicated the presence of heterogeneous dynamics in the polysaccharides where rigid cellulose and mobile hemicelluloses moieties existed together. PMID:24010724

  20. A roadmap for interpreting 13C metabolite labeling patterns from cells

    PubMed Central

    Buescher, Joerg M.; Antoniewicz, Maciek R.; Boros, Laszlo G.; Burgess, Shawn C.; Brunengraber, Henri; Clish, Clary B.; DeBerardinis, Ralph J.; Feron, Olivier; Frezza, Christian; Ghesquiere, Bart; Gottlieb, Eyal; Hiller, Karsten; Jones, Russell G.; Kamphorst, Jurre J.; Kibbey, Richard G.; Kimmelman, Alec C.; Locasale, Jason W.; Lunt, Sophia Y.; Maddocks, Oliver D. K.; Malloy, Craig; Metallo, Christian M.; Meuillet, Emmanuelle J.; Munger, Joshua; Nöh, Katharina; Rabinowitz, Joshua D.; Ralser, Markus; Sauer, Uwe; Stephanopoulos, Gregory; St-Pierre, Julie; Tennant, Daniel A.; Wittmann, Christoph; Vander Heiden, Matthew G.; Vazquez, Alexei; Vousden, Karen; Young, Jamey D.; Zamboni, Nicola; Fendt, Sarah-Maria

    2015-01-01

    Measuring intracellular metabolism has increasingly led to important insights in biomedical research. 13C tracer analysis, although less information-rich than quantitative 13C flux analysis that requires computational data integration, has been established as a time-efficient method to unravel relative pathway activities, qualitative changes in pathway contributions, and nutrient contributions. Here, we review selected key issues in interpreting 13C metabolite labeling patterns, with the goal of drawing accurate conclusions from steady state and dynamic stable isotopic tracer experiments. PMID:25731751

  1. 13C NMR spectroscopy of methane adsorbed in SAPO-11 molecular sieve

    NASA Astrophysics Data System (ADS)

    Koskela, Tuomas; Ylihautala, Mika; Vaara, Juha; Jokisaari, Jukka

    1996-10-01

    Static 13C and 13C-{ 1H} NMR spectra of carbon-13 enriched methane ( 13CH 4) adsorbed into SAPO-11 molecular sieve were recorded at variable temperatures. Moreover, the corresponding MAS NMR spectra were measured. These experiments reveal a temperature-dependent, anisotropic and asymmetric 13C nuclear shielding tensor. Ab initio model calculations of methane in the field of a positive point charge suggest that the deformation of the shielding tensor may be related to the interaction between the methane molecule and the charge-compensating protons. A comparison with existing Xe data is made.

  2. Quinone-based stable isotope probing for assessment of 13C substrate-utilizing bacteria

    NASA Astrophysics Data System (ADS)

    Kunihiro, Tadao; Katayama, Arata; Demachi, Toyoko; Veuger, Bart; Boschker, Henricus T. S.; van Oevelen, Dick

    2015-04-01

    13C abundance in the quinone. In this study, we verified carbon stable isotope of quinone compared with bulk carbon stable isotope of bacterial culture. Results indicated a good correlation between carbon stable isotope of quinone compared with bulk carbon stable isotope. However, our measurement conditions for detection of quinone isotope-ions incurred underestimation of 13C abundance in the quinone. The quinone-SIP technique needs further optimization for measurement conditions of LC-MS/MS.

  3. Enhancing the Accuracy of Carbonate δ18O and δ13C Measurements by SIMS

    NASA Astrophysics Data System (ADS)

    Orland, I. J.; Kozdon, R.; Linzmeier, B.; Wycech, J.; Sliwinski, M.; Kitajima, K.; Kita, N.; Valley, J. W.

    2015-12-01

    The precision and accuracy of carbonate δ18O & δ13C analysis by multicollector SIMS is well established if standards match samples in structure and major/minor element chemistry. However, low-T- and bio-carbonates used to construct paleoclimate archives can include complex internal structures and some samples analyzed at WiscSIMS (and other SIMS labs) have a consistent, sample-dependent offset between average SIMS δ18O measurements and bulk δ18O analyses by phosphoric-acid digestion. The offset is typically <1‰, but recent work has discovered samples where the offset is greater — up to 1.8‰ (average SIMS δ18O values < corresponding conventional measurements). Notably, δ13C offsets have not been observed even in samples with a δ18O offset. We conducted tests to characterize the δ18O offset in different low-T carbonate materials. Multiple potential causes were examined: perhaps the measured offset is real and conventional analyses include material that SIMS excludes (and vice versa); analytical errors and inter-lab (mis)calibration; depth-profiling effects; porosity; and the effects of variable minor element composition. One explanation implicates water and/or organic matter within carbonate that is ionized during SIMS analysis, but sometimes removed for bulk analysis. Two diagnostic tools help monitor such contaminants during SIMS analysis: 1) simultaneous measurement of [16O1H], and 2) secondary ion yield. Offsets of 0.3 to 1.8‰ in δ18O correlate to [16O1H] for 7 studies of Nautilus, foraminifera, pteropods and speleothems. Offsets were not observed in all foraminifera. For Nautilus, foraminifera, otoliths, and speleothems we also tested pre-treatment techniques (e.g. vacuum roasting, hydrogen peroxide), for which there is no agreed procedure in conventional bulk analyses. For SIMS analyses, pre-treatments had varied influence on the δ18O value, [16O1H], the concentration of "organic markers" like 12C14N and 31P, and mineralogy (of aragonite

  4. Synthesis of D-[U-{sup 13}C]Glucal, D-[U-{sup 13}C] Galactal, and L-[U-{sup 13}C]Fucose for NMR structure studies of oligosaccharides

    SciTech Connect

    Wu, R.; Unkefer, C.J.; Silks, L.A. III

    1996-12-31

    The role of carbohydrates is well recognized in a variety of important biological phenomena such as cell surface recognition. Recent advances in carbohydrate chemistry, including the development of solid phase synthesis methods, have helped to provide significant quantities of material by offering general protocols for synthesis of well-defined, pure material. However, the study of the solution structure of oligosaccharides by nuclear magnetic resonance techniques have been hampered by the lack of enriched {sup 13}C material. In an effort to help alleviate this situation, we have been interested in the construction of the title compounds from a single economical carbon source, D-[U-{sup 13}C]glucose. Details of the syntheses will be provided.

  5. Carbon Metabolism of Soil microorganisms at Low Temperatures: Position-Specific 13C Labeled Glucose Reveals the Story

    NASA Astrophysics Data System (ADS)

    Apostel, C.; Bore, E. K.; Halicki, S.; Kuzyakov, Y.; Dippold, M.

    2015-12-01

    Metabolic pathway activities at low temperature are not well understood, despite the fact that the processes are relevant for many soils globally and seasonally. To analyze soil metabolism at low temperature, isotopomeres of position-specifically 13C labeled glucose were applied at three temperature levels; +5, -5 -20 oC. In additon, one sterilization treatment with sodium azide at +5 oC was also performed. Soils were incubated for 1, 3 and 10 days while soil samples at -20 oC were additionally sampled after 30 days. The 13C from individual molecule position in respired CO2 was quantifed. Incorporation of 13C in bulk soil, extractable microbial biomass by chloroform fumigation extraction (CFE) and cell membranes of different microbial communities classified by 13C phospholipid fatty acid analysis (PLFA) was carried out. Our 13CO2 data showed a dominance of C-1 respiration at +5 °C for treatments with and without sodium azide, but total respiration for sodium azide inhibited treatments increased by 14%. In contrast, at -5 and -20 oC metabolic behavior showed intermingling of preferential respiration of the glucose C-4 and C-1 positions. Therefore, at +5 °C, pentose phosphate pathway activity is a dominant metabolic pathway used by microorganisms to metabolize glucose. The respiration increase due to NaN3 inhibition was attributed to endoenzymes released from dead organisms that are stabilized at the soil matrix and have access to suitable substrate and co-factors to permit their funtions. Our PLFA analysis showed that incorporation of glucose 13C was higher in Gram negative bacteria than other microbial groups as they are most competitive for LMWOS. Only a limited amount of microbial groups maintained their glucose utilizing activity at -5 and -20 °C and they strongly shifted towards a metabolization of glucose via both glycolysis and pentose phosphate pathways indicating both growth and cellular maintenance. This study revealed a remarkable microbial acitivity

  6. The effect of biochar amendment on the soil microbial community - PLFA analyses and 13C labeling results

    NASA Astrophysics Data System (ADS)

    Watzinger, A.; Feichtmair, S.; Rempt, F.; Anders, E.; Wimmer, B.; Kitzler, B.; Zechmeister-Boltenstern, S.; Horacek, M.; Zehetner, F.; Kloss, S.; Richoz, S.; Soja, G.

    2012-04-01

    The effects of biochar amendment on plant growth and on the chemical / physical soil characteristics are well explored but only few studies have investigated the impact on soil microorganisms. The response of the soil microbial community to biochar amendment was investigated by phospholipid fatty acid (PLFA) analysis in (i) a large scale pot experiment, (ii) a small scale pot experiment using 13C labeled biochar and (iii) an incubation study using 13C labeled biochar. In the large scale pot experiment, three different agricultural soils from Austria (Planosol, Cambisol, Chernozem) and four different types of biochar were investigated. In total, 25 treatments with 5 replicates each were set up and monitored over a year. The results from the pot experiments showed no significant influence of biochar amendment on the total microbial biomass in the first 100 days after biochar addition. However, discriminant analysis showed a distinction of biochar and control soils as well as a strong effect of the pyrolysis temperature on the microbial composition. The effect of biochar was dependent on the type of soil. In the Planosol, some PLFAs were affected positively, especially when adding biochar with a low pyrolysis temperature, in the first month. In the long term, microbial community composition altered. Growth of fungi and gram negative bacteria was enhanced. In the Chernozem, PLFAs from various microbial groups decreased in the long term. Variability in the incubation study was low. Consequently, many PLFAs were significantly affected by biochar amendment. Again, in the Planosol, gram negative bacteria, actinomycetes and, after 2 weeks, gram positive bacteria increased under biochar amendment whereas in the chernozem total microbial biomass and gram positive bacteria were negatively affected in the long term. The 13C labeling studies confirmed the low degradability of the biochar, i.e. no alteration of the content and the δ13C in the soil organic matter within 100 days

  7. Assessment of metabolic fluxes in the mouse brain in vivo using 1H-[13C] NMR spectroscopy at 14.1 Tesla.

    PubMed

    Xin, Lijing; Lanz, Bernard; Lei, Hongxia; Gruetter, Rolf

    2015-05-01

    (13)C magnetic resonance spectroscopy (MRS) combined with the administration of (13)C labeled substrates uniquely allows to measure metabolic fluxes in vivo in the brain of humans and rats. The extension to mouse models may provide exclusive prospect for the investigation of models of human diseases. In the present study, the short-echo-time (TE) full-sensitivity (1)H-[(13)C] MRS sequence combined with high magnetic field (14.1 T) and infusion of [U-(13)C6] glucose was used to enhance the experimental sensitivity in vivo in the mouse brain and the (13)C turnover curves of glutamate C4, glutamine C4, glutamate+glutamine C3, aspartate C2, lactate C3, alanine C3, γ-aminobutyric acid C2, C3 and C4 were obtained. A one-compartment model was used to fit (13)C turnover curves and resulted in values of metabolic fluxes including the tricarboxylic acid (TCA) cycle flux VTCA (1.05 ± 0.04 μmol/g per minute), the exchange flux between 2-oxoglutarate and glutamate Vx (0.48 ± 0.02 μmol/g per minute), the glutamate-glutamine exchange rate V(gln) (0.20 ± 0.02 μmol/g per minute), the pyruvate dilution factor K(dil) (0.82 ± 0.01), and the ratio for the lactate conversion rate and the alanine conversion rate V(Lac)/V(Ala) (10 ± 2). This study opens the prospect of studying transgenic mouse models of brain pathologies. PMID:25605294

  8. Stable Carbon Isotopes (δ 13C) in Coral Skeletons: Experimental Approach and Applications for Paleoceanography

    NASA Astrophysics Data System (ADS)

    Grottoli, A. G.

    2004-12-01

    Scleractinian corals obtain fixed carbon via photosynthesis by their endosymbiotic algae (zooxanthellae) and via hetertrophy (injestion of zooplankton, δ 13C ≈ -17 to -22‰ ). Carbon dioxide (CO2) used for photosynthesis is obtained from seawater (δ 13C ≈ 0%) or from respired CO2 within the coral host. The δ 13C of the carbon used in the formation of the underlying coral skeleton is fractionated as a result of both of these metabolic processes. Here I have pooled evidence from several field and tank experiments on the effect of photosynthesis and heterotrophy of coral skeletal δ 13C. In the experiments, decreases in light levels due to shading or depth resulted in a significant decrease in skeletal δ 13C in all species studied (Pavona gigantea, Pavona clavus, Porites compressa). Decreases in photosynthesis in bleached corals also resulted in a decrease in skeletal δ 13C compared to non-bleached corals growing under the same conditions and at the same location. Skeletal δ 13C also decreased at higher than normal light levels most likely due to photoinhibition. Thus, decreases in photosynthesis due to reduced light levels, due to bleaching-induced decreases in chlorophyll a concentrations, or due to photodamage-induced decreases in functional cholorphyll a, results in significant δ 13C decreases. Comprehensive interpretation of all of the data showed that changes in photosynthesis itself can drive the changes in δ 13C. In field experiments, the addition of natural concentrations of zooplankton to the diet resulted in decreases in skeletal δ 13C. Such a decrease was more pronounced with depth and in P. gigantea compared to P. clavus. In situ feeding experiments have since confirmed these findings. However under tank conditions with unaturally high feeding rates, enhanced nitrogen supply in the diet can disrupt the coral-algal symbiosis, stimlate zooxanthellae growth and photosynthesis, and cause an incrase in skeletal δ 13C. It is proposed that under

  9. Glucose-methanol co-utilization in Pichia pastoris studied by metabolomics and instationary 13C flux analysis

    PubMed Central

    2013-01-01

    Background Several studies have shown that the utilization of mixed carbon feeds instead of methanol as sole carbon source is beneficial for protein production with the methylotrophic yeast Pichia pastoris. In particular, growth under mixed feed conditions appears to alleviate the metabolic burden related to stress responses triggered by protein overproduction and secretion. Yet, detailed analysis of the metabolome and fluxome under mixed carbon source metabolizing conditions are missing. To obtain a detailed flux distribution of central carbon metabolism, including the pentose phosphate pathway under methanol-glucose conditions, we have applied metabolomics and instationary 13C flux analysis in chemostat cultivations. Results Instationary 13C-based metabolic flux analysis using GC-MS and LC-MS measurements in time allowed for an accurate mapping of metabolic fluxes of glycolysis, pentose phosphate and methanol assimilation pathways. Compared to previous results from NMR-derived stationary state labelling data (proteinogenic amino acids, METAFoR) more fluxes could be determined with higher accuracy. Furthermore, using a thermodynamic metabolic network analysis the metabolite measurements and metabolic flux directions were validated. Notably, the concentration of several metabolites of the upper glycolysis and pentose phosphate pathway increased under glucose-methanol feeding compared to the reference glucose conditions, indicating a shift in the thermodynamic driving forces. Conversely, the extracellular concentrations of all measured metabolites were lower compared with the corresponding exometabolome of glucose-grown P. pastoris cells. The instationary 13C flux analysis resulted in fluxes comparable to previously obtained from NMR datasets of proteinogenic amino acids, but allowed several additional insights. Specifically, i) in vivo metabolic flux estimations were expanded to a larger metabolic network e.g. by including trehalose recycling, which accounted for

  10. Trimethylation Enhancement Using (13)C-Diazomethane ((13)C-TrEnDi): Increased Sensitivity and Selectivity of Phosphatidylethanolamine, Phosphatidylcholine, and Phosphatidylserine Lipids Derived from Complex Biological Samples.

    PubMed

    Canez, Carlos R; Shields, Samuel W J; Bugno, Magdalena; Wasslen, Karl V; Weinert, Hillary P; Willmore, William G; Manthorpe, Jeffrey M; Smith, Jeffrey C

    2016-07-19

    Significant sensitivity enhancements in the tandem mass spectrometry-based analysis of complex mixtures of several phospholipid classes has been achieved via (13)C-TrEnDi. (13)C-TrEnDi-modified phosphatidylethanolamine (PE), phosphatidylserine (PS), and phosphatidylcholine (PC) lipids extracted from HeLa cells demonstrated greater sensitivity via precursor ion scans (PISs) than their unmodified counterparts. Sphingomyelin (SM) species exhibited neither an increased nor decreased sensitivity following modification. The use of isotopically labeled diazomethane enabled the distinction of modified PE and modified PC species that would yield isobaric species with unlabeled diazomethane. (13)C-TrEnDi created a PE-exclusive PIS of m/z 202.1, two PS-exclusive PISs of m/z 148.1 and m/z 261.1, and a PIS of m/z 199.1 for PC species (observed at odd m/z values) and SM species (observed at even m/z values). The standardized average area increase after TrEnDi modification was 10.72-fold for PE species, 2.36-fold for PC, and 1.05-fold for SM species. The sensitivity increase of PS species was not quantifiable, as there were no unmodified PS species identified prior to derivatization. (13)C-TrEnDi allowed for the identification of 4 PE and 7 PS species as well as the identification and quantitation of an additional 4 PE and 4 PS species that were below the limit of detection (LoD) prior to modification. (13)C-TrEnDi also pushed 24 PE and 6 PC lipids over the limit of quantitation (LoQ) that prior to modification were above the LoD only. PMID:27275841

  11. 13C MR imaging of methionine-rich gliomas at 4.7T: a pilot study.

    PubMed

    Sasao, Akira; Hirai, Toshinori; Iriguchi, Norio; Nakamura, Hideo; Kudo, Mareina; Sasao, Ako; Yamashita, Yasuyuki

    2011-01-01

    We explored the feasibility of using carbon-13 ((13)C) magnetic resonance imaging ((13)C-MRI) to depict (13)C-labeled methionine-enriched gliomas at 4.7 tesla. We transplanted 2 types of glioma cells separately to 2 subcutaneous tissue sites on the backs of mice weighing 15 to 20 g. After confirming tumor growth, we used (13)C-MRI and (1)H-MRI to scan 4 mice that had been administered (13)C-labeled methionine and 2 control mice. (13)C-MRI of all 4 transplanted mice administered with (13)C-labeled methionine revealed 2 areas of hyperintensity that corresponded to the tumor sites on (1)H-MR images, but no such areas were visualized in transplanted controls. Our data suggest that (13)C-MRI can show the accumulation of (13)C-labeled tracer by gliomas. PMID:21720117

  12. Separation of extra- and intracellular metabolites using hyperpolarized 13C diffusion weighted MR

    NASA Astrophysics Data System (ADS)

    Koelsch, Bertram L.; Sriram, Renuka; Keshari, Kayvan R.; Leon Swisher, Christine; Van Criekinge, Mark; Sukumar, Subramaniam; Vigneron, Daniel B.; Wang, Zhen J.; Larson, Peder E. Z.; Kurhanewicz, John

    2016-09-01

    This work demonstrates the separation of extra- and intracellular components of glycolytic metabolites with diffusion weighted hyperpolarized 13C magnetic resonance spectroscopy. Using b-values of up to 15,000 s mm-2, a multi-exponential signal response was measured for hyperpolarized [1-13C] pyruvate and lactate. By fitting the fast and slow asymptotes of these curves, their extra- and intracellular weighted diffusion coefficients were determined in cells perfused in a MR compatible bioreactor. In addition to measuring intracellular weighted diffusion, extra- and intracellular weighted hyperpolarized 13C metabolites pools are assessed in real-time, including their modulation with inhibition of monocarboxylate transporters. These studies demonstrate the ability to simultaneously assess membrane transport in addition to enzymatic activity with the use of diffusion weighted hyperpolarized 13C MR. This technique could be an indispensible tool to evaluate the impact of microenvironment on the presence, aggressiveness and metastatic potential of a variety of cancers.

  13. Fusion cross section of 12C+13C at sub-barrier energies

    NASA Astrophysics Data System (ADS)

    Zhang, N. T.; Tang, X. D.; Chen, H.; Chesneanu, D.; Straticiuc, M.; Trache, L.; Burducea, I.; Li, K. A.; Li, Y. J.; Ghita, D. G.; Margineanu, R.; Pantelica, A.; Gomoiu, C.

    2016-02-01

    In the recent work at Notre Dame, correlations between three carbon isotope fusion systems have been studied and it is found that the fusion cross sections of 12C+13Cand 13C+13C provide an upper limit on the fusion cross section of the astrophysically important 12C+12C reaction.The aim of this work is to continue such research by measuring the fusion cross section of the 12C+13C reaction to lower energies. In this experiment, the off-line activity measurement was performed in the ultra-low background laboratory 12C+13C and the fusion cross section for has been determined in the energy range of Ec.m. =2.5-6.8 MeV. Comparison between this work and several models is also presented.

  14. Strongly polarizing weakly coupled 13C nuclear spins with optically pumped nitrogen-vacancy center

    PubMed Central

    Wang, Ping; Liu, Bao; Yang, Wen

    2015-01-01

    Enhancing the polarization of nuclear spins surrounding the nitrogen-vacancy (NV) center in diamond has recently attracted widespread attention due to its various applications. Here we present an analytical formula that not only provides a clear physical picture for the recently observed polarization reversal of strongly coupled13C nuclei over a narrow range of magnetic field [H. J. Wang et al., Nat. Commun. 4, 1940 (2013)], but also demonstrates the possibility to strongly polarize weakly coupled13C nuclei. This allows sensitive magnetic field control of the 13C nuclear spin polarization for NMR applications and significant suppression of the 13C nuclear spin noise to prolong the NV spin coherence time. PMID:26521962

  15. Separation of extra- and intracellular metabolites using hyperpolarized (13)C diffusion weighted MR.

    PubMed

    Koelsch, Bertram L; Sriram, Renuka; Keshari, Kayvan R; Leon Swisher, Christine; Van Criekinge, Mark; Sukumar, Subramaniam; Vigneron, Daniel B; Wang, Zhen J; Larson, Peder E Z; Kurhanewicz, John

    2016-09-01

    This work demonstrates the separation of extra- and intracellular components of glycolytic metabolites with diffusion weighted hyperpolarized (13)C magnetic resonance spectroscopy. Using b-values of up to 15,000smm(-2), a multi-exponential signal response was measured for hyperpolarized [1-(13)C] pyruvate and lactate. By fitting the fast and slow asymptotes of these curves, their extra- and intracellular weighted diffusion coefficients were determined in cells perfused in a MR compatible bioreactor. In addition to measuring intracellular weighted diffusion, extra- and intracellular weighted hyperpolarized (13)C metabolites pools are assessed in real-time, including their modulation with inhibition of monocarboxylate transporters. These studies demonstrate the ability to simultaneously assess membrane transport in addition to enzymatic activity with the use of diffusion weighted hyperpolarized (13)C MR. This technique could be an indispensible tool to evaluate the impact of microenvironment on the presence, aggressiveness and metastatic potential of a variety of cancers. PMID:27434780

  16. Preparation of 13C/15N-labeled oligomers using the polymerase chain reaction

    DOEpatents

    Chen, Xian; Gupta, Goutam; Bradbury, E. Morton

    2001-01-01

    Preparation of .sup.13 C/.sup.15 N-labeled DNA oligomers using the polymerase chain reaction (PCR). A PCR based method for uniform (.sup.13 C/.sup.15 N)-labeling of DNA duplexes is described. Multiple copies of a blunt-ended duplex are cloned into a plasmid, each copy containing the sequence of interest and restriction Hinc II sequences at both the 5' and 3' ends. PCR using bi-directional primers and uniformly .sup.13 C/.sup.15 N-labeled dNTP precursors generates labeled DNA duplexes containing multiple copies of the sequence of interest. Twenty-four cycles of PCR, followed by restriction and purification, gave the uniformly .sup.13 C/.sup.15 N-labeled duplex sequence with a 30% yield. Such labeled duplexes find significant applications in multinuclear magnetic resonance spectroscopy.

  17. Natural abundance measurements of 13C indicate increased deep soil carbon mineralization after forest disturbance

    NASA Astrophysics Data System (ADS)

    Diochon, Amanda; Kellman, Lisa

    2008-07-01

    Northern forest soils represent globally important stores of carbon (C), yet there is no consensus about how they are altered by the widespread practice of harvesting that dominates many forested landscapes. Here we present the first study to systematically investigate the utility of δ 13C and C content depth profiles to infer temporal changes in belowground carbon cycling processes following disturbance in a pure C3 ecosystem. We document carbon concentration and δ 13C depth profile enrichment trends consistent with a kinetic fractionation arising from soil organic carbon (SOC) humification across a northern forest chronosequence (1, 15, 45, 80 and 125+ yrs). Reduced soil C storage that coincided with observed soil profile δ 13C-enrichment patterns which intensified following clearcut harvesting, pointed to losses of SOC in the deeper (>20 cm) mineral soil. This study suggests the δ 13C approach may assist in identifying mechanisms responsible for soil C storage changes in disturbed C3 forest ecosystems.

  18. 2H-DNP-enhanced 2H–13C solid-state NMR correlation spectroscopy

    PubMed Central

    Maly, Thorsten; Andreas, Loren B.; Smith, Albert A.

    2015-01-01

    Perdeuteration of biological macromolecules for magic angle spinning solid-state NMR spectroscopy can yield high-resolution 2H–13C correlation spectra and the method is therefore of great interest for the structural biology community. Here we demonstrate that the combination of sample deuteration and dynamic nuclear polarization yields resolved 2H–13C correlation spectra with a signal enhancement of ε ≥ 700 compared to a spectrum recorded with microwaves off and otherwise identical conditions. To our knowledge, this is the first time that 2H-DNP has been employed to enhance MAS-NMR spectra of a biologically relevant system. The DNP process is studied using several polarizing agents and the technique is applied to obtain 2H–13C correlation spectra of U-[2H, 13C] proline. PMID:20458422

  19. Spectroscopic study and astronomical detection of doubly 13C-substituted ethyl cyanide

    NASA Astrophysics Data System (ADS)

    Margulès, L.; Belloche, A.; Müller, H. S. P.; Motiyenko, R. A.; Guillemin, J.-C.; Garrod, R. T.; Menten, K. M.

    2016-05-01

    Context. We have performed a spectral line survey called Exploring Molecular Complexity with ALMA (EMoCA) toward Sagittarius B2(N) between 84.1 and 114.4 GHz with the Atacama Large Millimeter/submillimeter Array (ALMA) in its Cycles 0 and 1. Line intensities of the main isotopic species of ethyl cyanide and its singly 13C-substituted isotopomers observed toward the hot molecular core Sagittarius B2(N2) suggest that the doubly 13C-substituted isotopomers should also be detectable. Aims: We want to determine the spectroscopic parameters of all three doubly 13C-substituted isotopologues of ethyl cyanide to search for them in our ALMA data. Methods: We investigated the laboratory rotational spectra of the three species between 150 GHz and 990 GHz. We searched for emission lines produced by these species in the ALMA spectrum of Sagittarius B2(N2). We modeled their emission and the emission of the 12C and singly 13C-substituted isotopologues assuming local thermodynamic equilibrium. Results: We identified more than 5000 rotational transitions, pertaining to more than 3500 different transition frequencies, in the laboratory for each of the three doubly 13C-substituted isotopomers. The quantum numbers reach J ≈ 115 and Ka ≈ 35, resulting in accurate spectroscopic parameters and accurate rest frequency calculations beyond 1000 GHz for strong to moderately weak transitions of either isotopomer. All three species are unambiguously detected in our ALMA data. The 12C/13C column density ratio of the isotopomers with one 13C atom to those with two 13C atoms is about 25. Conclusions: Ethyl cyanide is the second molecule after methyl cyanide for which isotopologues containing two 13C atoms have been securely detected in the interstellar medium. The model of our ethyl cyanide data suggests that we should be able to detect vibrational satellites of the main species up to at least ν19 = 1 at ~1130 K and up to ν13 + ν21 = 2 at ~600 K for the isotopologues with one 13C atom in

  20. Simultaneous DNP enhancements of (1)H and (13)C nuclei: theory and experiments.

    PubMed

    Shimon, Daphna; Hovav, Yonatan; Kaminker, Ilia; Feintuch, Akiva; Goldfarb, Daniella; Vega, Shimon

    2015-05-01

    DNP on heteronuclear spin systems often results in interesting phenomena such as the polarization enhancement of one nucleus during MW irradiation at the "forbidden" transition frequencies of another nucleus or the polarization transfer between the nuclei without MW irradiation. In this work we discuss the spin dynamics in a four-spin model system of the form {ea-eb-((1)H,(13)C)}, with the Larmor frequencies ωa, ωb, ωH and ωC, by performing Liouville space simulations. This spin system exhibits the common (1)H solid effect (SE), (13)C cross effect (CE) and in addition high order CE-DNP enhancements. Here we show, in particular, the "proton shifted (13)C-CE" mechanism that results in (13)C polarization when the model system, at one of its (13)C-CE conditions, is excited by a MW field at the zero quantum or double quantum electron-proton transitions ωMW = ωa ± ωH and ωMW = ωb ± ωH. Furthermore, we introduce the "heteronuclear" CE mechanism that becomes efficient when the system is at one of its combined CE conditions |ωa - ωb| = |ωH ± ωC|. At these conditions, simulations of the four-spin system show polarization transfer processes between the nuclei, during and without MW irradiation, resembling the polarization exchange effects often discussed in the literature. To link the "microscopic" four-spin simulations to the experimental results we use DNP lineshape simulations based on "macroscopic" rate equations describing the electron and nuclear polarization dynamics in large spin systems. This approach is applied based on electron-electron double resonance (ELDOR) measurements that show strong (1)H-SE features outside the EPR frequency range. Simulated ELDOR spectra combined with the indirect (13)C-CE (iCE) mechanism, result in additional "proton shifted (13)C-CE" features that are similar to the experimental ones. These features are also observed experimentally in (13)C-DNP spectra of a sample containing 15 mM of trityl in a glass forming solution of

  1. A procedure to validate and correct the 13C chemical shift calibration of RNA datasets.

    PubMed

    Aeschbacher, Thomas; Schubert, Mario; Allain, Frédéric H-T

    2012-02-01

    Chemical shifts reflect the structural environment of a certain nucleus and can be used to extract structural and dynamic information. Proper calibration is indispensable to extract such information from chemical shifts. Whereas a variety of procedures exist to verify the chemical shift calibration for proteins, no such procedure is available for RNAs to date. We present here a procedure to analyze and correct the calibration of (13)C NMR data of RNAs. Our procedure uses five (13)C chemical shifts as a reference, each of them found in a narrow shift range in most datasets deposited in the Biological Magnetic Resonance Bank. In 49 datasets we could evaluate the (13)C calibration and detect errors or inconsistencies in RNA (13)C chemical shifts based on these chemical shift reference values. More than half of the datasets (27 out of those 49) were found to be improperly referenced or contained inconsistencies. This large inconsistency rate possibly explains that no clear structure-(13)C chemical shift relationship has emerged for RNA so far. We were able to recalibrate or correct 17 datasets resulting in 39 usable (13)C datasets. 6 new datasets from our lab were used to verify our method increasing the database to 45 usable datasets. We can now search for structure-chemical shift relationships with this improved list of (13)C chemical shift data. This is demonstrated by a clear relationship between ribose (13)C shifts and the sugar pucker, which can be used to predict a C2'- or C3'-endo conformation of the ribose with high accuracy. The improved quality of the chemical shift data allows statistical analysis with the potential to facilitate assignment procedures, and the extraction of restraints for structure calculations of RNA. PMID:22252483

  2. Parallel labeling experiments validate Clostridium acetobutylicum metabolic network model for (13)C metabolic flux analysis.

    PubMed

    Au, Jennifer; Choi, Jungik; Jones, Shawn W; Venkataramanan, Keerthi P; Antoniewicz, Maciek R

    2014-11-01

    In this work, we provide new insights into the metabolism of Clostridium acetobutylicum ATCC 824 obtained using a systematic approach for quantifying fluxes based on parallel labeling experiments and (13)C-metabolic flux analysis ((13)C-MFA). Here, cells were grown in parallel cultures with [1-(13)C]glucose and [U-(13)C]glucose as tracers and (13)C-MFA was used to quantify intracellular metabolic fluxes. Several metabolic network models were compared: an initial model based on current knowledge, and extended network models that included additional reactions that improved the fits of experimental data. While the initial network model did not produce a statistically acceptable fit of (13)C-labeling data, an extended network model with five additional reactions was able to fit all data with 292 redundant measurements. The model was subsequently trimmed to produce a minimal network model of C. acetobutylicum for (13)C-MFA, which could still reproduce all of the experimental data. The flux results provided valuable new insights into the metabolism of C. acetobutylicum. First, we found that TCA cycle was effectively incomplete, as there was no measurable flux between α-ketoglutarate and succinyl-CoA, succinate and fumarate, and malate and oxaloacetate. Second, an active pathway was identified from pyruvate to fumarate via aspartate. Third, we found that isoleucine was produced exclusively through the citramalate synthase pathway in C. acetobutylicum and that CAC3174 was likely responsible for citramalate synthase activity. These model predictions were confirmed in several follow-up tracer experiments. The validated metabolic network model established in this study can be used in future investigations for unbiased (13)C-flux measurements in C. acetobutylicum. PMID:25183671

  3. (13)C-Breath testing in animals: theory, applications, and future directions.

    PubMed

    McCue, Marshall D; Welch, Kenneth C

    2016-04-01

    The carbon isotope values in the exhaled breath of an animal mirror the carbon isotope values of the metabolic fuels being oxidized. The measurement of stable carbon isotopes in carbon dioxide is called (13)C-breath testing and offers a minimally invasive method to study substrate oxidation in vivo. (13)C-breath testing has been broadly used to study human exercise, nutrition, and pathologies since the 1970s. Owing to reduced use of radioactive isotopes and the increased convenience and affordability of (13)C-analyzers, the past decade has witnessed a sharp increase in the use of breath testing throughout comparative physiology-especially to answer questions about how and when animals oxidize particular nutrients. Here, we review the practical aspects of (13)C-breath testing and identify the strengths and weaknesses of different methodological approaches including the use of natural abundance versus artificially-enriched (13)C tracers. We critically compare the information that can be obtained using different experimental protocols such as diet-switching versus fuel-switching. We also discuss several factors that should be considered when designing breath testing experiments including extrinsic versus intrinsic (13)C-labelling and different approaches to model nutrient oxidation. We use case studies to highlight the myriad applications of (13)C-breath testing in basic and clinical human studies as well as comparative studies of fuel use, energetics, and carbon turnover in multiple vertebrate and invertebrate groups. Lastly, we call for increased and rigorous use of (13)C-breath testing to explore a variety of new research areas and potentially answer long standing questions related to thermobiology, locomotion, and nutrition. PMID:26660654

  4. Multi-year estimates of plant and ecosystem 13C discrimination at AmeriFlux sites

    NASA Astrophysics Data System (ADS)

    Dang, X.; Lai, C.; Hollinger, D. Y.; Bush, S.; Randerson, J. T.; Law, B. E.; Schauer, A. J.; Ehleringer, J.

    2011-12-01

    We estimated plant and ecosystem 13C discrimination continuously at 8 AmeriFlux sites (Howland Forest, Harvard Forest, Wind River Forest, Rannells Prairie, Freeman Ranch, Chestnut Ridge, Metolius, and Marys River fir) over 8 years (2002-2009). We used an observation-based approach from weekly measurements of eddy covariance CO2 fluxes and their 13C/12C ratios to estimate photosynthetic 13C discrimination (△A) and respiration (δ13CR) on seasonal and interannual time scales. The coordinated, systematic flask sampling across the AmeriFlux subnetwork were used for cross-site synthesis of monthly flux estimates [Dang et al. Combining tower mixing ratio and community model data to estimate regional-scale net ecosystem carbon exchange by boundary layer inversion over 4 flux towers in the U.S.A., Journal of Geophysical Research-Biogeosciences, in press]. Here, we evaluated environmental factors that also influenced temporal variability in △A and δ13CR from daily to interannual time scales, comparing atmospheric 13C/12C measurements, leaf and needle organic matter, and tree ring cellulose. Across these major biomes that dominate the continent, we show differential ecophysiological responses to environmental stresses, among which water availability appeared to be a dominant factor. Our decadal measurement period provided robust estimates of atmospheric 13C discrimination by terrestrial ecosystems, but also suggest regions where enhanced monitoring efforts are required (e.g., 13C/12C emission from fire and urban metabolism; increased temporal resolution of 13C measurements in stress-sensitive ecosystems) to make atmospheric 13C/12C measurements an effective constraint for continental-scale assessments of the terrestrial carbon cycle.

  5. Directly detected 55Mn MRI: Application to phantoms for human hyperpolarized 13C MRI development

    PubMed Central

    von Morze, Cornelius; Carvajal, Lucas; Reed, Galen D.; Swisher, Christine Leon; Tropp, James; Vigneron, Daniel B.

    2014-01-01

    In this work we demonstrate for the first time directly detected manganese-55 (55Mn) MRI using a clinical 3T MRI scanner designed for human hyperpolarized 13C clinical studies with no additional hardware modifications. Due to the similar frequency of the 55Mn and 13C resonances, the use of aqueous permanganate for large, signal-dense, and cost-effective “13C” MRI phantoms was investigated, addressing the clear need for new phantoms for these studies. Due to 100% natural abundance, higher intrinsic sensitivity, and favorable relaxation properties, 55Mn MRI of aqueous permanganate demonstrates dramatically increased sensitivity over typical 13C phantom MRI, at greatly reduced cost as compared with large 13C-enriched phantoms. A large sensitivity advantage (22-fold) was demonstrated. A cylindrical phantom (d= 8 cm) containing concentrated aqueous sodium permanganate (2.7M) was scanned rapidly by 55Mn MRI in a human head coil tuned for 13C, using a balanced SSFP acquisition. The requisite penetration of RF magnetic fields into concentrated permanganate was investigated by experiments and high frequency electromagnetic simulations, and found to be sufficient for 55Mn MRI with reasonably sized phantoms. A sub-second slice-selective acquisition yielded mean image SNR of ~60 at 0.5cm3 spatial resolution, distributed with minimum central signal ~40% of the maximum edge signal. We anticipate that permanganate phantoms will be very useful for testing HP 13C coils and methods designed for human studies. PMID:25179135

  6. Extreme (13)C depletion of carbonates formed during oxidation of biogenic methane in fractured granite.

    PubMed

    Drake, Henrik; Åström, Mats E; Heim, Christine; Broman, Curt; Åström, Jan; Whitehouse, Martin; Ivarsson, Magnus; Siljeström, Sandra; Sjövall, Peter

    2015-01-01

    Precipitation of exceptionally 13C-depleted authigenic carbonate is a result of, and thus a tracer for, sulphate-dependent anaerobic methane oxidation, particularly in marine sediments. Although these carbonates typically are less depleted in 13C than in the source methane, because of incorporation of C also from other sources, they are far more depleted in 13C13C as light as -69‰ V-PDB) than in carbonates formed where no methane is involved. Here we show that oxidation of biogenic methane in carbon-poor deep groundwater in fractured granitoid rocks has resulted in fracture-wall precipitation of the most extremely 13C-depleted carbonates ever reported, δ13C down to -125‰ V-PDB. A microbial consortium of sulphate reducers and methane oxidizers has been involved, as revealed by biomarker signatures in the carbonates and S-isotope compositions of co-genetic sulphide. Methane formed at shallow depths has been oxidized at several hundred metres depth at the transition to a deep-seated sulphate-rich saline water. This process is so far an unrecognized terrestrial sink of methane. PMID:25948095

  7. Extreme 13C depletion of carbonates formed during oxidation of biogenic methane in fractured granite

    PubMed Central

    Drake, Henrik; Åström, Mats E.; Heim, Christine; Broman, Curt; Åström, Jan; Whitehouse, Martin; Ivarsson, Magnus; Siljeström, Sandra; Sjövall, Peter

    2015-01-01

    Precipitation of exceptionally 13C-depleted authigenic carbonate is a result of, and thus a tracer for, sulphate-dependent anaerobic methane oxidation, particularly in marine sediments. Although these carbonates typically are less depleted in 13C than in the source methane, because of incorporation of C also from other sources, they are far more depleted in 13C13C as light as −69‰ V-PDB) than in carbonates formed where no methane is involved. Here we show that oxidation of biogenic methane in carbon-poor deep groundwater in fractured granitoid rocks has resulted in fracture-wall precipitation of the most extremely 13C-depleted carbonates ever reported, δ13C down to −125‰ V-PDB. A microbial consortium of sulphate reducers and methane oxidizers has been involved, as revealed by biomarker signatures in the carbonates and S-isotope compositions of co-genetic sulphide. Methane formed at shallow depths has been oxidized at several hundred metres depth at the transition to a deep-seated sulphate-rich saline water. This process is so far an unrecognized terrestrial sink of methane. PMID:25948095

  8. Perfusion and diffusion sensitive 13C stimulated-echo MRSI for metabolic imaging of cancer.

    PubMed

    Larson, Peder E Z; Hurd, Ralph E; Kerr, Adam B; Pauly, John M; Bok, Robert A; Kurhanewicz, John; Vigneron, Daniel B

    2013-06-01

    Metabolic imaging with hyperpolarized [1-(13)C]-pyruvate can rapidly probe tissue metabolic profiles in vivo and has been shown to provide cancer imaging biomarkers for tumor detection, progression, and response to therapy. This technique uses a bolus injection followed by imaging within 1-2 minutes. The observed metabolites include vascular components and their generation is also influenced by cellular transport. These factors complicate image interpretation, especially since [1-(13)C]lactate, a metabolic product that is a biomarker of cancer, is also produced by red blood cells. It would be valuable to understand the distribution of metabolites between the vasculature, interstitial space, and intracellular compartments. The purpose of this study was to better understand this compartmentalization by using a perfusion and diffusion-sensitive stimulated-echo acquisition mode (STEAM) MRSI acquisition method tailored to hyperpolarized substrates. Our results in mouse models showed that among metabolites, the injected substrate (13)C-pyruvate had the largest vascular fraction overall while (13)C-alanine had the smallest vascular fraction. We observed a larger vascular fraction of pyruvate and lactate in the kidneys and liver when compared to back muscle and prostate tumor tissue. Our data suggests that (13)C-lactate in prostate tumor tissue voxels was the most abundant labeled metabolite intracellularly. This was shown in STEAM images that highlighted abnormal cancer cell metabolism and suppressed vascular (13)C metabolite signals. PMID:23260391

  9. Development of a 13C-optimized 1.5-mm high temperature superconducting NMR probe

    NASA Astrophysics Data System (ADS)

    Ramaswamy, Vijaykumar; Hooker, Jerris W.; Withers, Richard S.; Nast, Robert E.; Brey, William W.; Edison, Arthur S.

    2013-10-01

    We report a 1.5-mm NMR probe based on high temperature superconductors operating at 14.1 T optimized for 13C detection. The probe has a total sample volume of about 35 microliters (μL) with an active volume of 20 μL and provides exceptional mass sensitivity for 13C detection. The probe also has excellent 1H sensitivity and employs a 2H lock; 15N irradiation capability can be added in the future. The coils are cooled to about 20 K using a standard Agilent cryogenic refrigeration system, and the sample temperature is regulated near room temperature. The coil design considerations are discussed in detail. This probe is ideal for directly detected 13C NMR experiments for natural products chemistry and metabolomics applications, for which 35 μL is an optimal sample volume. The outstanding 13C sensitivity of this probe allowed us to directly determine the 13C connectivity on 1.1 mg of natural abundance histidine using an INADEQUATE experiment. We demonstrated the utility of this probe for 13C-based metabolomics using a synthetic mixture of common natural abundance metabolites whose concentrations ranged from 1 to 5 mM (40-200 nmol).

  10. R-Matrix Analysis of the 13C(α,n)16O Reaction

    NASA Astrophysics Data System (ADS)

    Kock, Arthur; Rogachev, Grigory

    2015-10-01

    The 13C(α,n)16O reaction plays a crucial role in the main s-process occurring in low-mass thermally-pulsing asymptotic giant branch (TP-AGB) stars, which produces about half of all nuclei heavier than iron. However, direct measurements of this reaction cross section near the Gamow-peak energy are currently not possible due to very small reaction cross sections. Additionally, available cross-section data at higher energy have some inconsistencies, leading to significant uncertainties in low energy extrapolations. A global R-matrix fit was conducted, using all available data for the 13C(α,n)16O, 13C(α, α)13C, and 16O(n,n)16O reactions. Of particular importance was the inclusion of the fixed ANC for the 1 / 2 + state at 6 . 356 MeV in 17O, which was measured recently using the sub-Coulomb α-transfer reaction, as well as the new 13C+ α elastic-scattering data measured in the low-energy region 1 . 6 - 3 . 8 MeV. Important constraining information on various resonances was found, and the uncertainty for the astrophysical 13C(α,n)16O reaction rate was dramatically reduced. Much work on the analysis was done by A. K. Nurmukhanbetova from National Laboratory Astana in Astana, Kazakhstan.

  11. The paper trail of the 13C of atmospheric CO2 since the industrial revolution period

    NASA Astrophysics Data System (ADS)

    Yakir, Dan

    2011-07-01

    The 13C concentration in atmospheric CO2 has been declining over the past 150 years as large quantities of 13C-depleted CO2 from fossil fuel burning are added to the atmosphere. Deforestation and other land use changes have also contributed to the trend. Looking at the 13C variations in the atmosphere and in annual growth rings of trees allows us to estimate CO2 uptake by land plants and the ocean, and assess the response of plants to climate. Here I show that the effects of the declining 13C trend in atmospheric CO2 are recorded in the isotopic composition of paper used in the printing industry, which provides a well-organized archive and integrated material derived from trees' cellulose. 13C analyses of paper from two European and two American publications showed, on average, a - 1.65 ± 1.00‰ trend between 1880 and 2000, compared with - 1.45 and - 1.57‰ for air and tree-ring analyses, respectively. The greater decrease in plant-derived 13C in the paper we tested than in the air is consistent with predicted global-scale increases in plant intrinsic water-use efficiency over the 20th century. Distinct deviations from the atmospheric trend were observed in both European and American publications immediately following the World War II period.

  12. Metabolism of [13C5]hydroxyproline in vitro and in vivo: implications for primary hyperoxaluria

    PubMed Central

    Jiang, Juquan; Johnson, Lynnette C.; Knight, John; Callahan, Michael F.; Riedel, Travis J.; Holmes, Ross P.

    2012-01-01

    Hydroxyproline (Hyp) metabolism is a key source of glyoxylate production in the body and may be a major contributor to excessive oxalate production in the primary hyperoxalurias where glyoxylate metabolism is impaired. Important gaps in our knowledge include identification of the tissues with the capacity to degrade Hyp and the development of model systems to study this metabolism and how to suppress it. The expression of mRNA for enzymes in the pathway was examined in 15 different human tissues. Expression of the complete pathway was identified in liver, kidney, pancreas, and small intestine. HepG2 cells also expressed these mRNAs and enzymes and were shown to metabolize Hyp in the culture medium to glycolate, glycine, and oxalate. [18O]- and [13C5]Hyp were synthesized and evaluated for their use with in vitro and in vivo models. [18O]Hyp was not suitable because of an apparent tautomerism of [18O]glyoxylate between enol and hydrated forms, which resulted in a loss of isotope. [13C5]Hyp, however, was metabolized to [13C2]glycolate, [13C2]glycine, and [13C2]oxalate in vitro in HepG2 cells and in vivo in mice infused with [13C5]Hyp. These model systems should be valuable tools for exploring various aspects of Hyp metabolism and will be useful in determining whether blocking Hyp catabolism is an effective therapy in the treatment of primary hyperoxaluria. PMID:22207577

  13. (13) C Breath Tests Are Feasible in Patients With Extracorporeal Membrane Oxygenation Devices.

    PubMed

    Bednarsch, Jan; Menk, Mario; Malinowski, Maciej; Weber-Carstens, Steffen; Pratschke, Johann; Stockmann, Martin

    2016-07-01

    Temporary extracorporeal membrane oxygenation (ECMO) has been established as an essential part of therapy in patients with pulmonary or cardiac failure. As physiological gaseous exchange is artificially altered in this patient group, it is debatable whether a (13) C-breath test can be carried out. In this proof of technical feasibility report, we assess the viability of the (13) C-breath test LiMAx (maximum liver function capacity) in patients on ECMO therapy. All breath probes for the test device were obtained directly via the membrane oxygenator. Data of four patients receiving liver function assessment with the (13) C-breath test LiMAx while having ECMO therapy were analyzed. All results were compared with validated scenarios of the testing procedures. The LiMAx test could successfully be carried out in every case without changing ECMO settings. Clinical course of the patients ranging from multiorgan failure to no sign of liver insufficiency was in accordance with the results of the LiMAx liver function test. The (13) C-breath test is technically feasible in the context of ECMO. Further evaluation of (13) C-breath test in general would be worthwhile. The LiMAx test as a (13) C-breath test accessing liver function might be of particular predictive interest if patients with ECMO therapy develop multiorgan failure. PMID:26527580

  14. sup 13 C and sup 18 O isotopic disequilibrium in biological carbonates: I. Patterns

    SciTech Connect

    McConnaughey, T. )

    1989-01-01

    Biological carbonates frequently precipitate out of {sup 18}O and {sup 13}C equilibrium with ambient waters. Two patterns of isotopic disequilibrium are particularly common. Kinetic disequilibria, so designated because they apparently result from kinetic isotope effects during CO{sub 2} hydration and hydroxylation, involve simultaneous depletions of {sup 18}O and {sup 13}C as large as 4{per thousand} and 10 to 15{per thousand}, respectively. Rapid skeletogenesis favors strong kinetic effects, and approximately linear correlations between skeletal {delta}{sup 18}O and {delta}{sup 13}C are common in carbonates showing mainly the kinetic pattern. Metabolic effects involve additional positive or negative modulation of skeletal {delta}{sup 13}C, reflecting changes in the {delta}{sup 13}C of dissolved inorganic carbon, caused mainly by photosynthesis and respiration. Kinetic isotope disequilibria tend to be fairly consistent in rapidly growing parts of photosynthetic corals, and time dependent isotopic variations therefore reflect changes in environmental conditions. {delta}{sup 18}O variations from Galapagos corals yields meaningful clues regarding seawater temperature, while {delta}{sup 13}C variations reflect changes in photosynthesis, modulated by cloudiness.

  15. In vivo 13 carbon metabolic imaging at 3T with hyperpolarized 13C-1-pyruvate.

    PubMed

    Kohler, S J; Yen, Y; Wolber, J; Chen, A P; Albers, M J; Bok, R; Zhang, V; Tropp, J; Nelson, S; Vigneron, D B; Kurhanewicz, J; Hurd, R E

    2007-07-01

    We present for the first time dynamic spectra and spectroscopic images acquired in normal rats at 3T following the injection of (13)C-1-pyruvate that was hyperpolarized by the dynamic nuclear polarization (DNP) method. Spectroscopic sampling was optimized for signal-to-noise ratio (SNR) and for spectral resolution of (13)C-1-pyruvate and its metabolic products (13)C-1-alanine, (13)C-1-lactate, and (13)C-bicarbonate. Dynamic spectra in rats were collected with a temporal resolution of 3 s from a 90-mm axial slab using a dual (1)H-(13)C quadrature birdcage coil to observe the combined effects of metabolism, flow, and T(1) relaxation. In separate experiments, spectroscopic imaging data were obtained during a 17-s acquisition of a 20-mm axial slice centered on the rat kidney region to provide information on the spatial distribution of the metabolites. Conversion of pyruvate to lactate, alanine, and bicarbonate occurred within a minute of injection. Alanine was observed primarily in skeletal muscle and liver, while pyruvate, lactate, and bicarbonate concentrations were relatively high in the vasculature and kidneys. In contrast to earlier work at 1.5 T, bicarbonate was routinely observed in skeletal muscle as well as the kidney and vasculature. PMID:17659629

  16. Development of a 13C-Optimized 1.5-mm High Temperature Superconducting NMR Probe

    PubMed Central

    Ramaswamy, Vijaykumar; Hooker, Jerris W.; Withers, Richard S.; Nast, Robert E.; Brey, William W.; Edison, Arthur S.

    2013-01-01

    We report a 1.5-mm NMR probe based on high temperature superconductors operating at 14.1 T optimized for 13C detection. The probe has a total sample volume of about 35 microliters (μL) with an active volume of 20 μL and provides exceptional mass sensitivity for 13C detection. The probe also has excellent 1H sensitivity and employs a 2H channel lock; 15N irradiation capability can be added in the future. The coils are cooled to about 20 K using a standard Agilent cryogenic refrigeration system, and the sample temperature is regulated near room temperature. The coil design considerations are discussed in detail. This probe is ideal for directly detected 13C NMR experiments for natural products chemistry and metabolomics applications, for which 35 μL is an optimal sample volume. The outstanding 13C sensitivity of this probe allowed us to directly determine the 13C connectivity on 1.1 mg of natural abundance histidine using an INADEQUATE experiment. We demonstrated the utility of this probe for 13C-based metabolomics using a synthetic mixture of common natural abundance metabolites whose concentrations ranged from 1 to 5 mM (40 to 200 nmol). PMID:23969086

  17. ANALYSIS OF PERFLUORINATED CARBOXYLIC ACIDS IN SOILS: DETECTION AND QUANTITATION ISSUES AT LOW CONCENTRATIONS

    EPA Science Inventory