Relevant bibliographies by topics / Isotopic label

Academic literature on the topic 'Isotopic label'

Author: Grafiati
Published: 10 December 2022
Last updated: 28 January 2023

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Journal articles on the topic "Isotopic label"

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Seeger, Stefan, and Markus Weiler. "Temporal dynamics of tree xylem water isotopes: in situ monitoring and modeling." Biogeosciences 18, no. 15 (August 12, 2021): 4603–27. http://dx.doi.org/10.5194/bg-18-4603-2021.

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Abstract. We developed a setup for a fully automated, high-frequency in situ monitoring system of the stable water isotope deuterium and 18O in soil water and tree xylem. The setup was tested for 12 weeks within an isotopic labeling experiment during a large artificial sprinkling experiment including three mature European beech (Fagus sylvatica) trees. Our setup allowed for one measurement every 12–20 min, enabling us to obtain about seven measurements per day for each of our 15 in situ probes in the soil and tree xylem. While the labeling induced an abrupt step pulse in the soil water isotopic signature, it took 7 to 10 d until the isotopic signatures at the trees' stem bases reached their peak label concentrations and it took about 14 d until the isotopic signatures at 8 m stem height leveled off around the same values. During the experiment, we observed the effects of several rain events and dry periods on the xylem water isotopic signatures, which fluctuated between the measured isotopic signatures observed in the upper and lower soil horizons. In order to explain our observations, we combined an already existing root water uptake (RWU) model with a newly developed approach to simulate the propagation of isotopic signatures from the root tips to the stem base and further up along the stem. The key to a proper simulation of the observed short-term dynamics of xylem water isotopes was accounting for sap flow velocities and the flow path length distribution within the root and stem xylem. Our modeling framework allowed us to identify parameter values that relate to root depth, horizontal root distribution and wilting point. The insights gained from this study can help to improve the representation of stable water isotopes in trees within ecohydrological models and the prediction of transit time distribution and water age of transpiration fluxes.
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Miller, Benjamin F., Christopher A. Wolff, Fredrick F. Peelor, Patrick D. Shipman, and Karyn L. Hamilton. "Modeling the contribution of individual proteins to mixed skeletal muscle protein synthetic rates over increasing periods of label incorporation." Journal of Applied Physiology 118, no. 6 (March 15, 2015): 655–61. http://dx.doi.org/10.1152/japplphysiol.00987.2014.

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Advances in stable isotope approaches, primarily the use of deuterium oxide (2H2O), allow for long-term measurements of protein synthesis, as well as the contribution of individual proteins to tissue measured protein synthesis rates. Here, we determined the influence of individual protein synthetic rates, individual protein content, and time of isotopic labeling on the measured synthesis rate of skeletal muscle proteins. To this end, we developed a mathematical model, applied the model to an established data set collected in vivo, and, to experimentally test the impact of different isotopic labeling periods, used 2H2O to measure protein synthesis in cultured myotubes over periods of 2, 4, and 7 days. We first demonstrated the influence of both relative protein content and individual protein synthesis rates on measured synthesis rates over time. When expanded to include 286 individual proteins, the model closely approximated protein synthetic rates measured in vivo. The model revealed a 29% difference in measured synthesis rates from the slowest period of measurement (20 min) to the longest period of measurement (6 wk). In support of these findings, culturing of C2C12 myotubes with isotopic labeling periods of 2, 4, or 7 days revealed up to a doubling of the measured synthesis rate in the shorter labeling period compared with the longer period of labeling. From our model, we conclude that a 4-wk period of labeling is ideal for considering all proteins in a mixed-tissue fraction, while minimizing the slowing effect of fully turned-over proteins. In addition, we advocate that careful consideration must be paid to the period of isotopic labeling when comparing mixed protein synthetic rates between studies.
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Dudley, M. A., F. Jahoor, D. G. Burrin, and P. J. Reeds. "Brush-border disaccharidase synthesis in infant pigs measured in vivo with [2H3]leucine." American Journal of Physiology-Gastrointestinal and Liver Physiology 267, no. 6 (December 1, 1994): G1128—G1134. http://dx.doi.org/10.1152/ajpgi.1994.267.6.g1128.

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Conscious unrestrained piglets were fasted overnight and infused intravenously with [2H3]leucine for 6 h. Sucrase isomaltase and lactase phlorizin hydrolase were immunoprecipitated from jejunal mucosal membranes, and the immunoprecipitates were electrophoresed on polyacrylamide gels. Bands corresponding to the pro and mature isoforms of both enzymes were acid hydrolyzed. [2H3]leucine isotopic enrichment was measured by gas chromatography-mass spectrometry using negative chemical ionization. Plasma leucine reached isotopic steady state within 90 min. The isotopic enrichment of mucosal leucine was 73% of that of plasma leucine. The high mannose and complex glycosylated forms of prolactase were in isotopic equilibrium, and their isotopic enrichment was 94% of mucosal leucine. The fractional synthesis rates of total and membrane protein were 0.45 and 0.65 days-1, whereas the processing rates of mature lactase, sucrase, and isomaltase were 0.90, 0.23, and 0.21 days-1, respectively. Approximately 65% of the label in the sucrase isomaltase immunoprecipitate was in the complex glycosylated precursor, whereas 73% of the label in lactase phlorizin hydrolase was in the mature (160 kDa) form. We conclude that the low rate of brush-border sucrase synthesis reflects a slow rate at which the complex glycosylated precursor is processed to the brush-border form.
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Eglinton, T. I., M. A. Goñi, J. J. Boon, E. R. E. van der Hage, N. Terashima, and Y. Xie. "Incorporation of 13C-Labeled Coniferyl Alcohol into Developing Ginkgo biloba L. Lignin Revealed by Analytical Pyrolysis and CuO Oxidation in Combination with Isotope Ratio Monitoring-Gas Chromatography-Mass Spectrometry." Holzforschung 54, no. 1 (January 28, 2000): 39–54. http://dx.doi.org/10.1515/hf.2000.007.

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Summary A suite of four samples of xylem tissue from Ginkgo (Ginkgo biloba L.) shoots grown in a medium containing coniferin 13C-labeled at differing side-chain carbon atoms were studied using thermal and chemical degradation methods in combination with molecular-level isotopic analyses. The aims of the study were threefold: (1) to verify conclusions drawn from Nuclear Magnetic Resonance experiments previously performed on the same tissue samples, (2) to investigate degradation mechanisms and (3) to quantify the proportion of labeled material in each sample. Isotopic analysis of specific degradation products revealed the presence of the label exclusively within lignin-derived (phenolic) products and that the label is retained in its original position on the side-chain. These two results clearly indicate that there is no “scrambling” of carbon atoms as a result of thermal or chemical degradation, and thus lend strong support to analytical pyrolysis and chemolysis as viable approaches for structural investigations of the lignin macromolecule. Indeed, the isotopic enrichment of specific degradation products provides new evidence for certain types of linkages within the lignin polymer. The distribution and isotopic composition of the degradation products also strongly suggest an origin from newly-formed lignin as opposed to DHP-type products or unreacted substrate. As such, the data provides added confidence in the selective labeling approach for elucidation of the structure and biosynthesis of lignin. Isotopic mass balance calculations reveal that certain pyrolysis and CuO oxidation products show enhanced labeling which may be indicative of preferential incorporation of their specific precursors into the growing lignin macromolecule or heterogeneous lignin deposition.
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Studer, M. S., R. T. W. Siegwolf, M. Leuenberger, and S. Abiven. "Multi-isotope labelling (<sup>13</sup>C, <sup>18</sup>O, <sup>2</sup>H) of fresh assimilates to trace organic matter dynamics in the plant-soil system." Biogeosciences Discussions 11, no. 11 (November 18, 2014): 15911–43. http://dx.doi.org/10.5194/bgd-11-15911-2014.

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Abstract. Isotope labelling is a powerful tool to study elemental cycling within terrestrial ecosystems. Here we describe a new multi-isotope technique to label organic matter (OM). We exposed poplars (Populus deltoides x nigra) for 14 days to an atmosphere enriched in 13CO2 and depleted in 2H218O. After one week, the water-soluble leaf OM (δ13C = 1346 ± 162‰) and the leaf water were strongly labelled (δ18O = −63± 8‰, δ2H = −156 ± 15‰). The leaf water isotopic composition was between the atmospheric and stem water, indicating a considerable diffusion of vapour into the leaves (58–69%). The atomic ratios of the labels recovered (18O/13C, 2H/13C) were 2–4 times higher in leaves than in the stems and roots. This either indicates the synthesis of more condensed compounds (lignin vs. cellulose) in roots and stems, or be the result of O and H exchange and fractionation processes during transport and biosynthesis. We demonstrate that the three major OM elements (C, O, H) can be labelled and traced simultaneously within the plant. This approach could be of interdisciplinary interest for the fields of plant physiology, paleoclimatic reconstruction or soil science.
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Romsdahl, Trevor B., Shrikaar Kambhampati, Somnath Koley, Umesh P. Yadav, Ana Paula Alonso, Doug K. Allen, and Kent D. Chapman. "Analyzing Mass Spectrometry Imaging Data of 13C-Labeled Phospholipids in Camelina sativa and Thlaspi arvense (Pennycress) Embryos." Metabolites 11, no. 3 (March 4, 2021): 148. http://dx.doi.org/10.3390/metabo11030148.

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The combination of 13C-isotopic labeling and mass spectrometry imaging (MSI) offers an approach to analyze metabolic flux in situ. However, combining isotopic labeling and MSI presents technical challenges ranging from sample preparation, label incorporation, data collection, and analysis. Isotopic labeling and MSI individually create large, complex data sets, and this is compounded when both methods are combined. Therefore, analyzing isotopically labeled MSI data requires streamlined procedures to support biologically meaningful interpretations. Using currently available software and techniques, here we describe a workflow to analyze 13C-labeled isotopologues of the membrane lipid and storage oil lipid intermediate―phosphatidylcholine (PC). Our results with embryos of the oilseed crops, Camelina sativa and Thlaspi arvense (pennycress), demonstrated greater 13C-isotopic labeling in the cotyledons of developing embryos compared with the embryonic axis. Greater isotopic enrichment in PC molecular species with more saturated and longer chain fatty acids suggest different flux patterns related to fatty acid desaturation and elongation pathways. The ability to evaluate MSI data of isotopically labeled plant embryos will facilitate the potential to investigate spatial aspects of metabolic flux in situ.
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BLUCK, Leslie J. C., Allan T. CLAPPERTON, Cheryl V. KIDNEY, and W. Andy COWARD. "Glycogenesis and glucose oxidation during an intravenous glucose tolerance test in man." Clinical Science 106, no. 6 (June 1, 2004): 645–52. http://dx.doi.org/10.1042/cs20030353.

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The quantity of deuterated glucose customarily given in labelled IVGTTs (intravenous glucose tolerance tests) changes the isotopic composition of the subject's body water enough to be detected by mass spectrometric techniques. Glucose undergoing direct glycogenesis does not contribute label to the body water pool, and isotope incorporated into it must have come from glucose that has either been oxidized or undergone indirect glycogenesis. By subtracting the amount of label found in body water from the total amount of glucose utilized, as calculated from the minimal model of glucose disappearance, it should be possible to study the partitioning of the dose given between direct glycogenesis in skeletal muscle and other metabolic pathways. To establish these principles, we used isotope ratio MS to determine body water composition in groups of healthy (n=7; mean weight, 76 kg; fasting plasma glucose and insulin, 5.1 mmol and 40 pmol respectively) and Type II diabetic (n=5; mean weight, 84 kg; fasting plasma glucose and insulin, 6.2 mmol and 75 pmol respectively) subjects undergoing IVGTTs. It was found that, for healthy subjects, 31% of the dose given was utilized in direct glycogenesis and this was decreased to 15% in diabetes. Defects in muscle glycogen synthesis in diabetes of the same order are well known from magnetic resonance studies. We conclude that measurement of label incorporation into body water is potentially useful for investigation of the metabolism of a glucose load in vivo during an IVGTT.
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Studer, M. S., R. T. W. Siegwolf, M. Leuenberger, and S. Abiven. "Multi-isotope labelling of organic matter by diffusion of <sup>2</sup>H/<sup>18</sup>O-H<sub>2</sub>O vapour and <sup>13</sup>C-CO<sub>2</sub> into the leaves and its distribution within the plant." Biogeosciences 12, no. 6 (March 20, 2015): 1865–79. http://dx.doi.org/10.5194/bg-12-1865-2015.

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Abstract. Isotope labelling is a powerful tool to study elemental cycling within terrestrial ecosystems. Here we describe a new multi-isotope technique to label organic matter (OM). We exposed poplars (Populus deltoides × nigra) for 14 days to an atmosphere enriched in 13CO2 and depleted in 2H218O. After 1 week, the water-soluble leaf OM (δ13C = 1346 ± 162‰) and the leaf water were strongly labelled (δ18O = −63 ± 8, δ2H = −156 ± 15‰). The leaf water isotopic composition was between the atmospheric and stem water, indicating a considerable back-diffusion of vapour into the leaves (58–69%) in the opposite direction to the net transpiration flow. The atomic ratios of the labels recovered (18O/13C, 2H/13C) were 2–4 times higher in leaves than in the stems and roots. This could be an indication of the synthesis of more condensed compounds in roots and stems (e.g. lignin vs. cellulose) or might be the result of O and H exchange and fractionation processes during phloem transport and biosynthesis. We demonstrate that the three major OM elements (C, O, H) can be labelled and traced simultaneously within the plant. This approach could be of interdisciplinary interest in the fields of plant physiology, palaeoclimatic reconstruction or soil science.
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Dimitrova, Tsvetelina, Frank Repmann, and Dirk Freese. "Preparation of 15N-labeled Potassium Ferrocyanide for Tracer Studies." Environment and Pollution 6, no. 2 (September 29, 2017): 41. http://dx.doi.org/10.5539/ep.v6n2p41.

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Isotopic labels are widely used to trace the fate and cycling of common environmental contaminants. Many of the labeled materials are not available commercially and, depending on the complexity of the substance, the label and the enrichment level, custom syntheses are costly. A simple, straightforward, and cost effective method for the preparation of a highly enriched, 15N-labeled potassium ferrocyanide (K4[Fe(C15N)6]*3H2O) has been developed to meet the requirements of related tracer experiments and minimize their costs. In this case, the 15N label was used to quantify iron cyanide detoxification (biodegradation and/or transformation) within soil-plant-systems. 15N-labeled potassium cyanide (KC15N) and a ferrous iron salt have been used for the synthesis. Extensive qualitative and quantitative analyses showed a product, entirely identical in its functional and elemental components to commercial non-labeled K4[Fe(CN)6]*3H2O and in its 15N enrichment to the KC15N used for its synthesis. To investigate their behavior and fate in various environmental compartments, other labeled iron or metal cyanide complexes might be synthesized in analogous manner.
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Sheveleva, Nadezhda N., Denis A. Markelov, Mikhail A. Vovk, Irina I. Tarasenko, Mariya E. Mikhailova, Maxim Yu Ilyash, Igor M. Neelov, and Erkki Lahderanta. "Stable Deuterium Labeling of Histidine-Rich Lysine-Based Dendrimers." Molecules 24, no. 13 (July 6, 2019): 2481. http://dx.doi.org/10.3390/molecules24132481.

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Peptide dendrimers, due to their biocompatibility and low toxicity, are highly promising candidates as nanocarriers for drugs and genes. The development of this kind of delivery system requires reliable monitoring of their metabolic and biological pathways. In this respect, hydrogen isotope labeling has tremendous importance, being a safe tool for detection of the labeled nanocarriers. In this work, we have synthesized new histidine-rich lysine-based dendrimers (Lys-2His dendrimer) with two linear histidine (His) residues in every inner segment. The presence of His residues has enabled us to perform controlled deuteration of Lys-2His dendrimers. The high deuteration degree (around 70%) does not practically change after redissolving the samples in H2O and heating them at 40 °C, which indicates the isotopic label stability.
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Dissertations / Theses on the topic "Isotopic label"

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Tolbert, Thomas J. (Thomas James) 1969. "Synthesis of RNA with selective isotopic labels for NMR structural studies." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/50341.

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Breimark, Linda. "Investigating the use of isotope-labeled standards as calibrants in label-free quantification." Thesis, Uppsala universitet, Institutionen för biologisk grundutbildning, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-355130.

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The ability to accurately identify and quantify proteins in complexsamples is of great importance in the field of proteomics. Using massspectrometry, samples can be analysed and quantified either by theincorporation of a labelled standard of known concentration, or bylabel free quantification. Label free quantification has manybenefits, including time, cost, and ease of use, but is not asaccurate as the use of isotope label standards. In this project, thepossibility of increasing accuracy in quantification results from LFQusing a set of isotope labelled standards, QPrESTs, is investigated.The standards were produced by metabolic incorporation of heavyLysine and Arginine during expression inE. coli. They were then qualitycontrolled using SDS-PAGE for purity analysis, and LC-MS/MS forquantification and confirmation of MW. Human cell lysate samplesspiked with a set of 21 QPrEST standards were analysed by LC-MS/MSand quantified by QPrEST-H/L intensity ratios and intensity basedLFQ. In the LFQ protein quantification indices obtained from MaxQuantwere combined with BCA results, or with calibration curves obtainedfrom spiked in QPrEST standards. The LFQ results that best matchedthose obtained from QPrEST-H/L were those that used the calibrationcurves for quantification, which were found in a ~3-fold range, witha correlation coefficient varying from 0.67 to 1. Assuming thatQPrEST-H/L is the most accurate quantification method used, thisindicates that the use of QPrEST standards as calibrants can bebeneficial when it comes to increasing the accuracy in LFQ.
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Dainty, Jack Richard. "Use of isotopic labels and mathematical modelling to investigate mineral and vitamin bioavailability in humans." Thesis, University of East Anglia, 2010. https://ueaeprints.uea.ac.uk/10612/.

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This thesis describes the application of compartmental modelling techniques to data from human intervention studies with the objective of studying the absorption and metabolism of minerals (iron, copper, calcium) and vitamins (folate, carotenoids, riboflavin) labelled with stable isotopes. Compartmental modelling is a mathematical tool that uses differential equations to describe a dynamic process, such as nutrient metabolism, by adjusting the parameters of the equations until the model is a good fit to the real experimental data. A single compartment model was developed that can be used to estimate the quantity of absorbed (unlabelled) iron from a test drink containing a minimum of 10mg iron. Studies on copper demonstrated that approximately 74% of the absorbed dose is sequestered by the liver on “first-pass” and that large quantities of copper (2.4mg/d) are lost via the bile. Data from a calcium intervention trial was evaluated using a multi-compartment model and indicated that a moderately high salt intake (11.2g/d) was associated with a significantly negative bone calcium balance with a high calcium (1284mg/d) compared to a low calcium (518mg/d) diet (P=0.024). Modelling the initial metabolism of an absorbed dose of 13C-labelled folic acid resulted in the finding that it is not metabolised in the mucosal cells but (probably) in the liver. The absorptive efficiency of carotenoids was investigated by isolating the triglyceride rich lipoprotein fraction in plasma and a simple model was used to estimate β-carotene and lutein bioavailability. Results from the first stable isotope labelled riboflavin study indicated that the bioavailability of riboflavin from spinach (60±30%) was not significantly different to the bioavailability of riboflavin derived from milk (67±21%). The thesis has shown how compartmental modelling, in conjunction with stable isotope labelling, can reveal new insights into human mineral and vitamin metabolism, especially in the study of nutrient bioavailability.
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Thurston, Sean. "Studies towards the organocatalytic 'dialled in' synthesis of chiral, non-racemic aziridines, and amino acids, containing multiple isotopic labels." Thesis, University of East Anglia, 2012. https://ueaeprints.uea.ac.uk/42423/.

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Within this thesis, a highly effective one-pot methodology (based around the use of the organocatalyst pyridinium triflate) has been developed for the highly cis-selective synthesis of N-aryl 3-aryl-aziridine-2-carboxylates as racemates in yields of up to 80 %. This methodology has been extended by the use of a highly acidic C2 symmetric 3,3’- anthracenyl functionalised BINOL triflylphosphoramide organocatalyst, which allows for the formation of the desired cis- N-aryl 3-aryl-aziridine-2-carboxylates in an effective and highly enantioselective manner (affording the desired materials in yields of up to 81 %, and e.e.s of >99 %). Utilising the methodology developed within the first part of the thesis, enantio- and isotopically enriched cis- N-aryl 3-aryl-aziridine-2-carboxylates have been synthesised in a regioselective manner; with deuterium selectively introduced at the C2, and/or C3 positions of the aziridine ring with generally >90 % isotopic enrichment. Further to this, these aziridines have been submitted to ring opening methodologies in order to produce enantiomerically enriched a-amino acid derivatives bearing regioselectively introduced deuterium labels (with generally >90 % isotopic enrichment), in yields of up to 97 %, and e.e.s of up to 97 %, Finally, these methods have been combined in order to synthesise 5 target molecules consisting of functionalised enantioenriched a-amino acid derivatives bearing multiple isotopic labels including deuterium, 15N, and 18O, in what has become known as the ‘Dialled In’ methodology.
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Tannus, Andrea Ferreira Schuwartz. "Incorporação protéica de L[1-13C] leucina em ratos desnutridos:efeita da suplementação oral de glutamina." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/17/17138/tde-17022005-103658/.

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Não existe um consenso do efeito da suplementação de glutamina sobre a síntese protéica. No entanto, sugere-se que em animais desnutridos submetidos a trauma orgânico ou não, a glutamina além de seu papel no metabolismo energético, poderia ter efeito sobre a taxa de reciclagem protéica, tornando-se um aminoácido, condicionalmente, essencial. O objetivo deste trabalho foi determinar a incorporação protéica do aminoácido marcado 13C leucina em proteínas do plasma e da mucosa intestinal em ratos portadores de desnutrição protéico-calórica, suplementados ou não com glutamina via oral. Os animais foram pareados pelo peso/idade e subdivididos em 5 grupos: grupo controle nutrido (grupo 1), grupo controle desnutrido (grupo 2), grupo realimentado (grupo 2 A), grupo realimentado e suplementado com proteína e glutamina (grupo 2B) e grupo realimentado e suplementado com glutamina, a suplementação de glutamina por via oral durante 14 dias (0,42g/kg/dia). O estudo não teve por objetivo avaliar a fisiopatologia da desnutrição, mas sim o efeito terapêutico da oferta de glutamina no tratamento de animais desnutridos e em analogia, ao que ocorreria com pacientes desnutridos e internados. O estudo cinético efetuou-se por meio de infusão contínua  620mol/h L-[1-13C]-leucina durante 4 horas. O grupo de animais desnutridos (grupo 2), que recebeu 50% da alimentação recomendada, perdeu peso continuamente durante o experimento. Os grupos que receberam tratamentos dietoterápicos recuperaram o peso corporal, independente do tipo de realimentação e/ou suplementação de glutamina. O nitrogênio urinário teve comportamento similar ao do peso, ratificando o efeito de um tratamento dietético, independente da fonte de suplementação glutâmica. Os resultados de concentração plasmática de aminoácidos não foram uniformes tanto para os aminoácidos essenciais quanto para os aminoácidos considerados não essenciais. Reforçando tanto o ganho de peso, como a excreção de nitrogênio, tiveram comportamento semelhante independente da suplementação de glutamina. Na concentração plasmática de glutamina a diferença foi 64912 vs 17114mol/l, no grupo controle nutrido (grupo 1) e grupo controle desnutrido (grupo 2), respectivamente. Houve diferença significativa de enriquecimento plasmático isotópico de 13C leucina 1,270,5 vs 3,21,2, e enriquecimento de 13C KIC 1,930,6 vs 4,040,9 MPE%, respectivamente nos grupos 1 e 2. O enriquecimento isotópico de 13C leucina na proteína da mucosa intestinal, mostrou-se significativo entre os grupos 1 e 2, respectivamente, 0,00240,0006 vs 0,00200,0001 MPE% e o enriquecimento isotópico de 13C leucina livre apresentou-se semelhante com diferença entre os grupos 1 e 2, respectivamente 0,00190,00030 vs 0,00280,0007 MPE%. A taxa de síntese fracionada (FSR) foi menor no grupo controle desnutrido (grupo 2) 0,00370,0007/h em comparação ao grupo controle nutrido (grupo 1) 0,00440,0005/h e similar nos grupos experimentais. Conclui-se que a oferta de glutamina não estimulou ou alterou a incorporação protéica de aminoácido marcado, sendo que os resultados obtidos nos grupos suplementados com glutamina assemelharam-se aos encontrados no grupo de animais tratados com dieta. Desta maneira, sugere-se que o uso de suplemento de glutamina via oral não seja necessário no tratamento de animais desnutridos.
Nutritional status recovery is thought more effective when there are amino acids, especially, glutamine supplementation. The aim of the study was to verify the effect of glutamine on duodenal mucosa protein synthesis in the nourished or malnourished rats. The experimental groups animals received oral diet glutamine supplementation (0.42g/kg/day) for 14 days while the control group did not. Thereafter, kinetic study with L-[1-13C]-leucine to 4-h and biopsies of duodenal mucosa were done. The malnourished groups showed 25% weight loss with increase urinary nitrogen. Amino acid concentration in the plasma of control group was not significantly different with from that of the experimental groups. The result showed that 13C enrichment in the plasma and biopsy sample of the malnourished group is higher than that of the nourished group, but that of the fractional synthetic rate (FSR) is inverse; FSR of the nourished group is higher 0.00440.0005/h than that of the malnourished group 0.00370.0007/h.We conclude that oral supplementation glutamine does not acutely stimulate duodenal protein incorporation in malnourished rats, regardless the refilling protocol, with or without glutamine.
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Barton, Ashley M. "FATE OF STABLE ISOTOPE LABEL DURING PREDATION OF 15N-TAGGED WILD-TYPE ESCHERICHIA COLI BY PROTOZOA." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_theses/146.

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Currently, bacterial movement in karst aquifers is not well understood. Use of stable isotopes to label non-pathogenic Escherichia coli as a particulate groundwater tracer in karst systems has been examined in previous studies. Loss of the stable isotope signal is anticipated in traces greater than 500 m in length. Potential loss of 15N due to predation by protozoa was examined. Filter-sterilized water from Royal Spring in Georgetown, Kentucky, was inoculated with a mixture of either Tetrahymena pyriformis or Colpoda steinii and 15N-enriched E. coli and stored in the dark at 14°C. Samples were analyzed for their nitrogen isotope composition (as δ15N values), and for population counts of bacteria and protozoa in a time course experiment, on days zero and seven after inoculation. Protozoan populations increased in the presence of E. coli, while bacterial populations decreased. δ15N values increased in T. pyriformis fed enriched E. coli but did not show values as high as the bacteria themselves, indicating that attenuation via predation may be a concern in future groundwater traces.
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Cornelisen, Christopher David. "Nutrient Uptake by Seagrass Communities and Associated Organisms: Impact of Hydrodynamic Regime Quantified through Field Measurements and use of an Isotope Label." [Tampa, Fla. : s.n.], 2003. http://purl.fcla.edu/fcla/etd/SFE0000079.

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Chen, Gang 1963. "Chemical Mechanism of the Catalytic Subunit of Camp-Dependent Protein Kinase: Methods for Determining the Primary ¹⁸O Isotope Effects Using the Remote Label Technique." Thesis, University of North Texas, 1991. https://digital.library.unt.edu/ark:/67531/metadc500775/.

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A description of the nature of the transition state structure for phosphoryl transfer in the cAPK reaction requires a measurement of the primary 180 isotope effect at the serine hydroxyl acceptor. Since it is difficult to obtain primary 180 isotope effect directly, the 15N/1 4N ratio of the a-amine of the C-terminal glycine in the peptide Leu Arg-Lys-Ala-Ser-Leu-Gly (when serine is phosphorylated) was used to represent on the phosphorylation at serine. 15N Glycine, ' 4N-Glycine and 180 serine were synthesized and used to synthesize two peptides, one containing 1 80-serine/' 5 N glycine and second 1 60-serine/1 4N-glycine. Methods were developed for hydrolyzing the peptides and quantitatively isolating glycine. Partitioning results suggest that catalytic rate was slow compare to substrate dissociation. The 180 primary isotope effect will be determined in the near future using the method developed herein.
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Lording, William James. "A deeper understanding of the Diels–Alder reaction." Phd thesis, 2010. http://hdl.handle.net/1885/11776.

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The Diels-Alder reaction was discovered in 1928 and has become the most efficient and practical method for the synthesis of six-membered carbocyclic and heterocyclic rings. This thesis comprises three chapters of results and discussion with the Diels-Alder reaction as a theme. Chapter 2 details an investigation of endo:exo selectivity in the Diels-Alder reactions of 1,3-butadiene. Chapter 3 explores aspects of the intramolecular Diels-Alder reactions of some substituted 1,3,8-nonatrienes, and Chapter 4 describes the domino Diels-Alder reactions of 1,4-diiodo-1,3-butadiene. The Diels-Alder reaction is powerful, general, and widely used in chemical synthesis, and it is well known that many Diels-Alder reactions exhibit endo selectivity, in accord with Alder’s empirical rule. The origins of endo:exo selectivity in the Diels-Alder reaction, however, are not completely understood and there is a dearth of experimental evidence concerning the Diels-Alder reactions of the archetypal 1,3-diene, 1,3- butadiene. Chapter 2 describes a study of the Diels-Alder reactions of an isotopically labelled 1,3-butadiene with a range of simple dienophiles, allowing the endo:exo selectivities of these important reactions to be determined for the first time. The experimental data shed light on the origins of endo:exo selectivity in the Diels-Alder reaction and will serve as an important reference for future computational investigations in this area. The intramolecular Diels-Alder reaction shares many of the virtues of its intermolecular counterpart, however its use in chemical synthesis is limited because intramolecular Diels-Alder reactivity and stereoselectivity are often governed by subtle factors, and can be very difficult to predict. As part of a comprehensive experimental and computational collaboration, Chapter 3 describes an investigation of the heat and Lewis acid promoted intramolecular Diels-Alder reactions of some ether tethered 1,3,8-nonatrienes. Also presented are the results of a rate study and a kinetic isotope effect study involving the intramolecular Diels-Alder reactions of some 1,3,8-nonatrienes. The experimental data are analysed and compared with predicted stereoselectivities, activation barriers and kinetic isotope effects obtained from computational modelling. Increased efficiency in chemical synthesis conserves resources, reduces waste, and saves time and money. Domino reactions are particularly efficient processes, which can generate complex products from simple reactants. Chapter 4 describes an investigation of the domino Diels-Alder reactions of (1E,3E)-1,4-diiodo-1,3-butadiene with maleimide dienophiles, through which a family of bicyclo[2.2.2]oct-2-ene derivatives are produced in one high yielding and stereoselective synthetic step.
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Seibert, C., B. R. Davidson, B. J. Fuller, Laurence H. Patterson, W. J. Griffiths, and Y. Wang. "Multiple-approaches to the identification and quantification of cytochromes P450 in human liver tissue by mass spectrometry." 2009. http://hdl.handle.net/10454/6179.

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Here we report the identification and approximate quantification of cytochrome P450 (CYP) proteins in human liver microsomes as determined by nano-LC-MS/MS with application of the exponentially modified protein abundance index (emPAI) algorithm during database searching. Protocols based on 1D-gel protein separation and 2D-LC peptide separation gave comparable results. In total, 18 CYP isoforms were unambiguously identified based on unique peptide matches. Further, we have determined the absolute quantity of two CYP enzymes (2E1 and 1A2) in human liver microsomes using stable-isotope dilution mass spectrometry, where microsomal proteins were separated by 1D-gel electrophoresis, digested with trypsin in the presence of either a CYP2E1- or 1A2-specific stable-isotope labeled tryptic peptide and analyzed by LC-MS/MS. Using multiple reaction monitoring (MRM) for the isotope-labeled tryptic peptides and their natural unlabeled analogues quantification could be performed over the range of 0.1-1.5 pmol on column. Liver microsomes from four individuals were analyzed for CYP2E1 giving values of 88-200 pmol/mg microsomal protein. The CYP1A2 content of microsomes from a further three individuals ranged from 165 to 263 pmol/mg microsomal protein. Although, in this proof-of-concept study for CYP quantification, the two CYP isoforms were quantified from different samples, there are no practical reasons to prevent multiplexing the method to allow the quantification of multiple CYP isoforms in a single sample.
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Book chapters on the topic "Isotopic label"

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Allen, D. K., and R. G. Ratcliffe. "Quantification of Isotope Label." In Plant Metabolic Networks, 105–49. New York, NY: Springer New York, 2008. http://dx.doi.org/10.1007/978-0-387-78745-9_5.

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Kellermann, Josef, and Friedrich Lottspeich. "Isotope-Coded Protein Label." In Methods in Molecular Biology, 143–53. Totowa, NJ: Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-885-6_11.

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Kellermann, Josef. "ICPL—Isotope-Coded Protein Label." In Methods in Molecular Biology™, 113–23. Totowa, NJ: Humana Press, 2008. http://dx.doi.org/10.1007/978-1-60327-064-9_10.

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Huege, Jan, Jan Goetze, Frederik Dethloff, Bjoern Junker, and Joachim Kopka. "Quantification of Stable Isotope Label in Metabolites via Mass Spectrometry." In Methods in Molecular Biology, 213–23. Totowa, NJ: Humana Press, 2013. http://dx.doi.org/10.1007/978-1-62703-592-7_20.

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Mendes Junior, José Jair Alves, Carlos Eduardo Pontim, and Daniel Prado Campos. "Multi-label EMG Classification of Isotonic Hand Movements: A Suitable Method for Robotic Prosthesis Control." In XXVII Brazilian Congress on Biomedical Engineering, 1665–71. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-70601-2_243.

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Redfield, A. G., B. S. Choi, R. H. Griffey, M. Jarema, P. Rosevear, P. Hoben, R. Swanson, and D. Soll. "Proton NMR Studies of RNA’S and Related Enzymes Using Isotope Labels." In Structure and Dynamics of RNA, 99–112. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4684-5173-3_9.

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Huang, Danting, Benjamin C. Hudson, Yuan Gao, Evan K. Roberts, and Anant K. Paravastu. "Solid-State NMR Structural Characterization of Self-Assembled Peptides with Selective 13C and 15N Isotopic Labels." In Methods in Molecular Biology, 23–68. New York, NY: Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-7811-3_2.

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Puchalska, Patrycja, and Peter A. Crawford. "Application of Stable Isotope Labels for Metabolomics in Studies in Fatty Liver Disease." In Methods in Molecular Biology, 259–72. New York, NY: Springer New York, 2019. http://dx.doi.org/10.1007/978-1-4939-9488-5_20.

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Greco, Todd M., Amanda J. Guise, and Ileana M. Cristea. "Determining the Composition and Stability of Protein Complexes Using an Integrated Label-Free and Stable Isotope Labeling Strategy." In Methods in Molecular Biology, 39–63. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-3524-6_3.

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Barth, Johannes A. C., Michael Mader, Anssi Myrttinen, Veith Becker, Robert van Geldern, and Bernhard Mayer. "Advances in Stable Isotope Monitoring of CO2 Under Elevated Pressures, Temperatures and Salinities: Selected Results from the Project CO2ISO-LABEL." In Geological Storage of CO2 – Long Term Security Aspects, 59–71. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-13930-2_3.

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Conference papers on the topic "Isotopic label"

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Cui, Wanyun, and Sen Yan. "Isotonic Data Augmentation for Knowledge Distillation." In Thirtieth International Joint Conference on Artificial Intelligence {IJCAI-21}. California: International Joint Conferences on Artificial Intelligence Organization, 2021. http://dx.doi.org/10.24963/ijcai.2021/319.

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Knowledge distillation uses both real hard labels and soft labels predicted by teacher model as supervision. Intuitively, we expect the soft label probabilities and hard label probabilities to be concordant. However, in the real knowledge distillations, we found critical rank violations between hard labels and soft labels for augmented samples. For example, for an augmented sample x = 0.7 * cat + 0.3 * panda, a meaningful soft label distribution should have the same rank: P(cat|x)>P(panda|x)>P(other|x). But real teacher models usually violate the rank: P(tiger|x)>P(panda|x)>P(cat|x). We attribute the rank violations to the increased difficulty of understanding augmented samples for the teacher model. Empirically, we found the violations injuries the knowledge transfer. In this paper, we denote eliminating rank violations in data augmentation for knowledge distillation as isotonic data augmentation (IDA). We use isotonic regression (IR) -- a classic statistical algorithm -- to eliminate the rank violations. We show that IDA can be modeled as a tree-structured IR problem and gives an O(c*log(c)) optimal algorithm, where c is the number of labels. In order to further reduce the time complexity of the optimal algorithm, we also proposed a GPU-friendly approximation algorithm with linear time complexity. We have verified on variant datasets and data augmentation baselines that (1) the rank violation is a general phenomenon for data augmentation in knowledge distillation. And (2) our proposed IDA algorithms effectively increases the accuracy of knowledge distillation by solving the ranking violations.
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Boorman, Dale, Iestyn Pope, Wolfgang Langbein, Steve Hood, Paola Borri, and Pete Watson. "Optimisation of multimodal coherent anti-Stokes Raman scattering microscopy for the detection of isotope-labelled molecules." In Label-free Biomedical Imaging and Sensing (LBIS) 2019, edited by Natan T. Shaked and Oliver Hayden. SPIE, 2019. http://dx.doi.org/10.1117/12.2509280.

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POKIDYCHEV, ALEXANDRE, and MARINA POKIDYCHEVA. "ABOUT AN OPPORTUNITY OF APPLICATION OF AN ISOTOPE LABEL ON THE BASIS OF STABLE ISOTOPES TO MARK VARIOUS PRODUCTS." In Proceedings of the 3rd International Conference on Isotopes. WORLD SCIENTIFIC, 2000. http://dx.doi.org/10.1142/9789812793867_0113.

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Eberhart, Robert C. "Reflections on Quantitative Gamma Imaging of Cell-Surface Interactions." In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53388.

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Molecular and cellular interactions with foreign surfaces can be noninvasively measured by isotope imaging techniques. Long available for probing cell behavior, these techniques are now employed in molecular studies of disease progression, such as Alzheimer’s [1]. This paper reviews results obtained by noninvasive dual label gamma scintigraphy for the transient adhesion of platelets and neutrophils to pump-oxygenators during cardiopulmonary bypass (CPB). In this application, characteristic cell-foreign surface adhesion and release patterns are observed during CPB in the pig, as a function of oxygenator design and surface chemistry. Cell distributions in internal organs post-CPB are also affected by these processes. This method can be adapted to other settings where the understanding of protein-cell interactions with native and foreign surfaces is at issue, including fibrinogen-cell interactions, bacterial colonization, etc.
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Jacobson, K. Bruce, Heinrich F. Arlinghaus, Mitchel J. Doktycz, R. A. Sachleben, Gilbert M. Brown, and F. W. Larimer. "Development of resonance ionization spectroscopy for genome mapping and DNA sequencing using stable isotopes as DNA labels." In OE/LASE'93: Optics, Electro-Optics, & Laser Applications in Science& Engineering, edited by Richard A. Keller. SPIE, 1993. http://dx.doi.org/10.1117/12.146716.

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