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Auteur : Grafiati
Publié le 10 mars 2023

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1

Jacob, Arshia M., Karl M. Menten, Helmut Wiesemeyer, Rolf Güsten, Friedrich Wyrowski et Bernd Klein. « First detection of 13CH in the interstellar medium ». Astronomy & ; Astrophysics 640 (août 2020) : A125. http://dx.doi.org/10.1051/0004-6361/201937385.

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In recent years, a plethora of observations with high spectral resolution of sub-millimetre and far-infrared transitions of methylidene (CH), conducted with Herschel and SOFIA, have demonstrated this radical to be a valuable proxy for molecular hydrogen that can be used for characterising molecular gas within the interstellar medium on a Galactic scale, including the CO-dark component. We report the discovery of the 13CH isotopologue in the interstellar medium using the upGREAT receiver on board SOFIA. We have detected the three hyperfine structure components of the ≈2 THz frequency transition from its X2Π1∕2 ground-state towards the high-mass star-forming regions Sgr B2(M), G34.26+0.15, W49(N), and W51E and determined 13CH column densities. The ubiquity of molecules containing carbon in the interstellar medium has turned the determination of the ratio between the abundances of the two stable isotopes of carbon, 12C/13C, into a cornerstone for Galactic chemical evolution studies. Whilst displaying a rising gradient with galactocentric distance, this ratio, when measured using observations of different molecules (CO, H2CO, and others), shows systematic variations depending on the tracer used. These observed inconsistencies may arise from optical depth effects, chemical fractionation, or isotope-selective photo-dissociation. Formed from C+ either through UV-driven or turbulence-driven chemistry, CH reflects the fractionation of C+, and does not show any significant fractionation effects, unlike other molecules that were previously used to determine the 12C/13C isotopic ratio. This makes it an ideal tracer for the 12C/13C ratio throughout the Galaxy. By comparing the derived column densities of 13CH with previously obtained SOFIA data of the corresponding transitions of the main isotopologue 12CH, we therefore derive 12C/13C isotopic ratios toward Sgr B2(M), G34.26+0.15, W49(N) and W51E. Adding our values derived from 12∕13CH to previous calculations of the Galactic isotopic gradient, we derive a revised value of 12C/13C = 5.87(0.45)RGC + 13.25(2.94).
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Okada, Yoko, Ronan Higgins, Volker Ossenkopf-Okada, Cristian Guevara, Jürgen Stutzki et Marc Mertens. « First detection of [13C II] in the Large Magellanic Cloud ». Astronomy & ; Astrophysics 631 (novembre 2019) : L12. http://dx.doi.org/10.1051/0004-6361/201936685.

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Context. [13C II] observations in several Galactic sources show that the fine-structure [12C II] emission is often optically thick (the optical depths around 1 to a few). Aims. Our goal was to test whether this also affects the [12C II] emission from nearby galaxies like the Large Magellanic Cloud (LMC). Methods. We observed three star-forming regions in the LMC with upGREAT on board SOFIA at the frequency of the [C II] line. The 4 GHz bandwidth covers all three hyperfine lines of [13C II] simultaneously. For the analysis, we combined the [13C II] F = 1−0 and F = 1−1 hyperfine components as they do not overlap with the [12C II] line in velocity. Results. Three positions in N159 and N160 show an enhancement of [13C II] compared to the abundance-ratio-scaled [12C II] profile. This is likely due to the [12C II] line being optically thick, supported by the fact that the [13C II] line profile is narrower than [12C II], the enhancement varies with velocity, and the peak velocity of [13C II] matches the [O I] 63 μm self-absorption. The [12C II] line profile is broader than expected from a simple optical depth broadening of the [13C II] line, supporting the scenario of several PDR components in one beam having varying [12C II] optical depths. The derived [12C II] optical depth at three positions (beam size of 14″, corresponding to 3.4 pc) is 1−3, which is similar to values observed in several Galactic sources shown in previous studies. If this also applies to distant galaxies, the [C II] intensity will be underestimated by a factor of approximately 2.
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Bermel, Wolfgang, Isabella C. Felli, Rainer Kümmerle et Roberta Pierattelli. « 13C Direct-detection biomolecular NMR ». Concepts in Magnetic Resonance Part A 32A, no 3 (2008) : 183–200. http://dx.doi.org/10.1002/cmr.a.20109.

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Hong, Donghyun, Yaewon Kim, Chandrasekhar Mushti, Noriaki Minami, Anne Marie Gillepspie, Georgios Batsios, Celine Taglang et al. « TMET-16. DIRECT DETECTION OF 2HG AND GLUTAMATE PRODUCTION USING HYPERPOLARIZED [1-13C-5-12C]-Α-KETOGLUTARATE IN CELL AND IN VIVO GLIOMA MODELS ». Neuro-Oncology 24, Supplement_7 (1 novembre 2022) : vii265. http://dx.doi.org/10.1093/neuonc/noac209.1021.

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Abstract Mutant IDH leads to 2HG production, which drives glioma development. 13C MRS monitoring of hyperpolarized [1-13C]α-ketoglutarate (αKG) metabolism to 2HG and glutamate provides a non-invasive assessment of the IDH mutation and normal metabolism, respectively. However, monitoring 2HG production in vivo has been challenging because its resonance is within 0.1 ppm of the natural abundance [5-13C]αKG signal of the [1-13C]αKG substrate. Here, we utilized [1-13C -5-12C]αKG, which eliminated the [5-13C]αKG peak. This new approach, combined with an optimized sequence, made it possible to readily monitor the production of both 2HG and glutamate in cells and in vivo in healthy rats or rats with orthotopic patient-derived glioma. Hyperpolarized [1-13C -5-12C]αKG was injected into genetically engineered NHAIDHmut cell lysates, healthy rats, and rats implanted orthotopically with BT257 cells intravenously. 1-D dynamic 13C MRS spectra from cells and in vivo slab spectroscopy data were then acquired using an 11.7 T NMR system and a 3 T pre-clinical scanner, respectively. Injection of the hyperpolarized [1-13C -5-12C]αKG into cell lysates showed clearly detectable dynamic conversion of hyperpolarized [1-13C-5-12C]αKG to 2HG and glutamate. The normal brain showed clear production of glutamate but no 2HG was detected. In tumor-bearing rats, we were able to clearly detect the dynamic production of both 2HG and glutamate. This study demonstrated the utility of hyperpolarized [1-13C-5-12C]αKG as a substrate to clearly assess 2HG production without the confounding presence of the natural abundance peak which cannot be distinguished from 2HG in vivo. Importantly, the detection of 2HG provides a clear indicator of the IDH mutation within the tumor.
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Lai, Marta, Bernard Lanz, Carole Poitry-Yamate, Jackeline F. Romero, Corina M. Berset, Cristina Cudalbu et Rolf Gruetter. « In vivo 13C MRS in the mouse brain at 14.1 Tesla and metabolic flux quantification under infusion of [1,6-13C2]glucose ». Journal of Cerebral Blood Flow & ; Metabolism 38, no 10 (19 octobre 2017) : 1701–14. http://dx.doi.org/10.1177/0271678x17734101.

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In vivo 13C magnetic resonance spectroscopy (MRS) enables the investigation of cerebral metabolic compartmentation while, e.g. infusing 13C-labeled glucose. Metabolic flux analysis of 13C turnover previously yielded quantitative information of glutamate and glutamine metabolism in humans and rats, while the application to in vivo mouse brain remains exceedingly challenging. In the present study, 13C direct detection at 14.1 T provided highly resolved in vivo spectra of the mouse brain while infusing [1,6-13C2]glucose for up to 5 h. 13C incorporation to glutamate and glutamine C4, C3, and C2 and aspartate C3 were detected dynamically and fitted to a two-compartment model: flux estimation of neuron-glial metabolism included tricarboxylic acid cycle (TCA) flux in astrocytes (Vg = 0.16 ± 0.03 µmol/g/min) and neurons (VTCAn = 0.56 ± 0.03 µmol/g/min), pyruvate carboxylase activity (VPC = 0.041 ± 0.003 µmol/g/min) and neurotransmission rate (VNT = 0.084 ± 0.008 µmol/g/min), resulting in a cerebral metabolic rate of glucose (CMRglc) of 0.38 ± 0.02 µmol/g/min, in excellent agreement with that determined with concomitant 18F-fluorodeoxyglucose positron emission tomography (18FDG PET).We conclude that modeling of neuron-glial metabolism in vivo is accessible in the mouse brain from 13C direct detection with an unprecedented spatial resolution under [1,6-13C2]glucose infusion.
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Giesen, T. F., B. Mookerjea, G. W. Fuchs, A. A. Breier, D. Witsch, R. Simon et J. Stutzki. « First detection of the carbon chain molecules 13CCC and C13CC towards SgrB2(M) ». Astronomy & ; Astrophysics 633 (janvier 2020) : A120. http://dx.doi.org/10.1051/0004-6361/201936538.

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Context. Carbon molecules and their 13C-isotopologues can be used to determine the 12C/13C abundance ratios in stellar and interstellar objects. C3 is a pure carbon chain molecule found in star-forming regions and in stellar shells of carbon-rich late-type stars. Latest laboratory data of 13C-isotopologues of C3 allow a selective search for the mono-substituted species 13CCC and C13CC based on accurate ro-vibrational frequencies. Aims. We aim to provide the first detection of the 13C-isotopologues 13CCC and C13CC in space and to derive the 12C/13C ratio of interstellar gas in the massive star-forming region SgrB2(M) near the Galactic Center. Methods. We used the heterodyne receivers GREAT and upGREAT on board SOFIA to search for the ro-vibrational transitions Q(2) and Q(4) of 13CCC and C13CC at 1.9 THz along the line of sight towards SgrB2(M). In addition, to determine the local excitation temperature, we analyzed data from nine ro-vibrational transitions of the main isotopologue CCC in the frequency range between 1.6 and 1.9 THz, which were taken from the Herschel Science Data Archive. Results. We report the first detection of the isotopologues 13CCC and C13CC. For both species, the ro-vibrational absorption lines Q(2) and Q(4) have been identified, primarily arising from the warm gas physically associated with the strong continuum source, SgrB2(M). From the available CCC ro-vibrational transitions, we derived a gas excitation temperature of Tex = 44.4+4.7−3.9 K, and a total column density of N(CCC) = 3.88+0.39−0.35 × 1015 cm−2. Assuming the excitation temperatures of C13CC and 13CCC to be the same as for CCC, we obtained column densities of the 13C-isotopologues of N(C13CC) = 2.1+0.9−0.6 × 1014 cm−2 and N(13CCC) = 2.4+1.2−0.8 × 1014 cm−2. The derived 12C/13C abundance ratio in the C3 molecules is 20.5 ± 4.2, which is in agreement with the elemental ratio of 20, typically observed in SgrB2(M). However, we find the N(13CCC)/N(C13CC) ratio to be 1.2 ± 0.1, which is shifted from the statistically expected value of two. We propose that the discrepant abundance ratio arises due to the lower zero-point energy of C13CC, which makes position-exchange reaction converting 13CCC to C13CC energetically favorable.
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Jeffries, Rex E., Shawn M. Gomez, Jeffrey M. Macdonald et Michael P. Gamcsik. « Direct Detection of Glutathione Biosynthesis, Conjugation, Depletion and Recovery in Intact Hepatoma Cells ». International Journal of Molecular Sciences 23, no 9 (25 avril 2022) : 4733. http://dx.doi.org/10.3390/ijms23094733.

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Nuclear magnetic resonance (NMR) spectroscopy was used to monitor glutathione metabolism in alginate-encapsulated JM-1 hepatoma cells perfused with growth media containing [3,3′-13C2]-cystine. After 20 h of perfusion with labeled medium, the 13C NMR spectrum is dominated by the signal from the 13C-labeled glutathione. Once 13C-labeled, the high intensity of the glutathione resonance allows the acquisition of subsequent spectra in 1.2 min intervals. At this temporal resolution, the detailed kinetics of glutathione metabolism can be monitored as the thiol alkylating agent monobromobimane (mBBr) is added to the perfusate. The addition of a bolus dose of mBBr results in rapid diminution of the resonance for 13C-labeled glutathione due to a loss of this metabolite through alkylation by mBBr. As the glutathione resonance decreases, a new resonance due to the production of intracellular glutathione-bimane conjugate is detectable. After clearance of the mBBr dose from the cells, intracellular glutathione repletion is then observed by a restoration of the 13C-glutathione signal along with wash-out of the conjugate. These data demonstrate that standard NMR techniques can directly monitor intracellular processes such as glutathione depletion with a time resolution of approximately < 2 min.
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Jeffries, Rex E., Shawn M. Gomez, Jeffrey M. Macdonald et Michael P. Gamcsik. « Direct Detection of Glutathione Biosynthesis, Conjugation, Depletion and Recovery in Intact Hepatoma Cells ». International Journal of Molecular Sciences 23, no 9 (25 avril 2022) : 4733. http://dx.doi.org/10.3390/ijms23094733.

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Nuclear magnetic resonance (NMR) spectroscopy was used to monitor glutathione metabolism in alginate-encapsulated JM-1 hepatoma cells perfused with growth media containing [3,3′-13C2]-cystine. After 20 h of perfusion with labeled medium, the 13C NMR spectrum is dominated by the signal from the 13C-labeled glutathione. Once 13C-labeled, the high intensity of the glutathione resonance allows the acquisition of subsequent spectra in 1.2 min intervals. At this temporal resolution, the detailed kinetics of glutathione metabolism can be monitored as the thiol alkylating agent monobromobimane (mBBr) is added to the perfusate. The addition of a bolus dose of mBBr results in rapid diminution of the resonance for 13C-labeled glutathione due to a loss of this metabolite through alkylation by mBBr. As the glutathione resonance decreases, a new resonance due to the production of intracellular glutathione-bimane conjugate is detectable. After clearance of the mBBr dose from the cells, intracellular glutathione repletion is then observed by a restoration of the 13C-glutathione signal along with wash-out of the conjugate. These data demonstrate that standard NMR techniques can directly monitor intracellular processes such as glutathione depletion with a time resolution of approximately < 2 min.
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Nercessian, Olivier, Emma Noyes, Marina G. Kalyuzhnaya, Mary E. Lidstrom et Ludmila Chistoserdova. « Bacterial Populations Active in Metabolism of C1 Compounds in the Sediment of Lake Washington, a Freshwater Lake ». Applied and Environmental Microbiology 71, no 11 (novembre 2005) : 6885–99. http://dx.doi.org/10.1128/aem.71.11.6885-6899.2005.

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ABSTRACT Active members of the bacterial community in the sediment of Lake Washington, with special emphasis on C1 utilizers, were identified by employing two complementary culture-independent approaches: reverse transcription of environmental mRNA and 16S rRNA combined with PCR (RT-PCR) and stable-isotope probing (SIP) of DNA with the 13C-labeled C1 substrates methanol, methylamine, formaldehyde, and formate. Analysis of RT-PCR-amplified fragments of 16S rRNA-encoding genes revealed that gammaproteobacterial methanotrophs belonging to Methylobacter and Methylomonas dominate the active methylotroph population, while only one other known methylotrophic lineage, Methylophilaceae, was detected via this approach. Analysis of RT-PCR-amplified functional genes, pmoA and fae, allowed detection of alphaproteobacterial (Methylosinus) and gammaproteobacterial (Methylobacter, Methylomonas, and Methylomicrobium) methanotrophs, methylotrophs of the genus Methylobacterium, and yet-unidentified proteobacteria. SIP experiments allowed detection of a broad variety of groups actively metabolizing C1 compounds. Comparisons between 16S rRNA gene pools amplified from [13C]DNA and from [12C]DNA revealed that the proportion of Methylophilus-related sequences increased in the presence of [13C]methanol, [13C]methylamine, and [13C]formaldehyde; Novosphingobium-related sequences were enriched in the presence of [13C]methanol; Gemmatimonadaceae-related sequences were enriched in the presence of [13C]formaldehyde and [13C]formate; and Xanthomonadaceae-related sequences were enriched in the presence of [13C]formate. Analysis of fae genes amplified from [13C]DNAs isolated from different microcosms revealed specific shifts in populations in response to a specific C1 compound: Methylosinus sequences dominated the [13C]methanol microcosm pool, and beta- and gammaproteobacterial sequences dominated the [13C]methylamine microcosm pool. The [13C]formaldehyde microcosm was dominated by betaproteobacterial sequences and by sequences of a nonaffiliated group, while the [13C]formate microcosm was dominated by alpha- and betaproteobacterial sequences. Overall, these data point toward the presence of a diverse population of active methylotrophs in Lake Washington sediments and toward the existence of yet-uncultivated organisms.
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Dénès, Fabrice, Julien Farard et Jacques Lebreton. « Synthesis of 13C-Labeled Steroids ». Synthesis 51, no 23 (13 septembre 2019) : 4311–37. http://dx.doi.org/10.1055/s-0037-1611914.

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Due to the wide spectrum of biological activities of steroids, the detection and quantification of steroidal residues in various biological materials are crucial for drug development, doping prevention, and environmental protection. In addition, the analytical technique of stable isotopic dilution (SID) by Liquid Chromatography-Mass Spectrometry (LC-MS) requires 13C-labeled steroids as standards to provide accurate and reproducible steroid quantification. In this context, the synthesis of 13C-labeled steroids is reviewed. The approaches based on partial synthesis starting from commercially available steroids have been, by far, the most commonly employed strategy.1 Introduction2 Hemisynthesis of 13C3-Labeled Steroids via Partial Degradation of the A Ring2.1 Degradation of the A Ring to an Enol Lactone2.1.1 Introduction of 13C Atom(s) via Claisen Condensation: Turner’s Strategy2.1.2 Introduction of 13C Atom(s) with 13C-Labeled 5-(Diethylphosphono)pentan-2-one Ethylene Ketal Based on the Fujimoto–Belleau Reaction2.2 Degradation of the A Ring and Introduction of 13C Atom(s) with [13C3]-1-(Triphenylphosphoranylidene)propan-2-one3 Construction of the A Ring from an α,β-Unsaturated Ketone with 13C-Labeled 1-Iodo-3,3-(ethylenedioxy)butane as Electrophile4 Construction of the A and B rings: Stork’s Strategy5 Hemisynthesis with Introduction of 13C Atom(s) in the C17 Side Chain6 Conclusion
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Kajiwara, Masahiro, Kazuhiko Takatori, Yoshifumi Nakajima et Miyako Hirose. « Photolysis of 13C-Methylcobalamin. Direct Detection of Generated Formaldehyde by Using 13C-Labeling ». HETEROCYCLES 47, no 2 (1998) : 717. http://dx.doi.org/10.3987/com-97-s(n)43.

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Kuiper, T. B. H., F. F. Gardner, J. B. Whiteoak, W. L. Peters et J. E. Reynolds. « Detection of the 20 ↠ 3-1 Transition of 13CH3OH ». Symposium - International Astronomical Union 136 (1989) : 179. http://dx.doi.org/10.1017/s0074180900186504.

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The 20 → 3−1 E-type transition of 13CH3OH at 14.78 GHz has been detected towards four continuum sources: Sgr B2, two positions in Sgr A (the peaks of the ' + 20 km/s' and the '40 km/s' clouds), and W33. The NASA Deep Space Network 70-m antenna near Canberra, Australia, which has a 66 arcsec beam at this frequency, was used. A comparison of the 13C and 12C profiles for Sgr B2 indicates a rest frequency of 14,782.27 ± .03 MHz, 0.12 MHz above the laboratory value of Haque et al. (1974). For the Galactic Centre sources, the 12C/13C abundance ratios derived using the simplest assumptions lie in the range 30–40, higher than the 20–25 range derived from H2CO observations. For W33 the apparent value of ∼ 50 is lower than the value of ∼100 derived by Henkel et al. (1983) from H2CO. There may be no discrepancy, however, as W33 contains two velocity components — the higher velocity one at 36 km/s is more prominent in CH3OH and the lower 33 km/s more prominent in H2CO.
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Padovan, G. « Detection of adulteration of commercial honey samples by the 13C/12C isotopic ratio ». Food Chemistry 82, no 4 (septembre 2003) : 633–36. http://dx.doi.org/10.1016/s0308-8146(02)00504-6.

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Çinar, Serap B., Aziz Ekşi et İlknur Coşkun. « Carbon isotope ratio (13C/12C) of pine honey and detection of HFCS adulteration ». Food Chemistry 157 (août 2014) : 10–13. http://dx.doi.org/10.1016/j.foodchem.2014.02.006.

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Yamaguchi, Yoshiki, Markus Wälchli, Mayumi Nagano et Koichi Kato. « A 13C-detection NMR approach for large glycoproteins ». Carbohydrate Research 344, no 4 (mars 2009) : 535–38. http://dx.doi.org/10.1016/j.carres.2008.12.003.

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Vetter, Dirk, et Werner Thorn. « 13C-NMR Spectroscopic Detection of Malto-oligosaccharide Complexes ». Starch - Stärke 44, no 7 (1992) : 271–74. http://dx.doi.org/10.1002/star.19920440708.

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Siuka, Darko, Kristina Kumer, Borut Stabuc, David Stubljar, David Drobne et Rado Jansa. « Abbreviated 13C-mixed triglyceride breath test for detection of pancreatic exocrine insufficiency performs equally as standard 5-hour test in patients after gastrectomy performed for gastric cancer ». Radiology and Oncology 56, no 3 (14 août 2022) : 390–97. http://dx.doi.org/10.2478/raon-2022-0034.

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Abstract Background 13C-mixed triglyceride breath test (13C-MTGT) is a non-invasive test for the detection of moderate and severe pancreatic exocrine insufficiency (PEI), but it requires prolonged breath sampling. The aim of this study was to determine the diagnostic power of abbreviated 13C-MTGT in detecting PEI in patients after subtotal and total gastrectomy performed due to gastric cancer. Subjects and methods This cross-sectional observational study included 3 groups of subjects; healthy controls, patients with subtotal and patients with total gastrectomy. Demographic and clinical data of patients were collected. Stool samples to determine faecal elastase (Fe-1) and chymotrypsin were collected and measured by ELISA. All subjects performed 5-hour 13C-MTGT breath test. The concentration and relative content of 13C in exhaled air was measured by isotope ratio mass spectrometer (IRMS). PEI was confirmed as values of 13C-exhalation < 26.8% after 5 hours. Results Overall, 65 participants were included into analysis, 22 having PEI (n = 11 after subtotal and n = 11 after total gastrectomy, both performed for gastric cancer). 13C-MTGT breath test showed difference in percent of exhaled 13C between PEI and non-PEI patients already after 60 minutes (p = 0.034). Receiver operating characteristic (ROC) curve analysis showed that cut-off value of 13.74% after 150 minutes is showing equivalent diagnostic power to the longer test with sensitivity and specificity both above 90% for the exclusion of PEI in patients after subtotal and/or total gastrectomy. Conclusions In this study abbreviated 13C-MTGT test could be shortened from 5 to 2.5 hours without decrease in its diagnostic accuracy for detection of PEI in patients with subtotal or total gastrectomy performed for gastric cancer. This allows significant time savings in the diagnostics of PEI in this subgroup of patients.
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Cabin-Flaman, Armelle, Anne-Francoise Monnier, Yannick Coffinier, Jean-Nicolas Audinot, David Gibouin, Tom Wirtz, Rabah Boukherroub et al. « Combining combing and secondary ion mass spectrometry to study DNA on chips using 13C and 15N labeling ». F1000Research 5 (20 juin 2016) : 1437. http://dx.doi.org/10.12688/f1000research.8361.1.

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Dynamic secondary ion mass spectrometry (D-SIMS) imaging of combed DNA – the combing, imaging by SIMS or CIS method – has been developed previously using a standard NanoSIMS 50 to reveal, on the 50 nm scale, individual DNA fibers labeled with different, non-radioactive isotopes in vivo and to quantify these isotopes. This makes CIS especially suitable for determining the times, places and rates of DNA synthesis as well as the detection of the fine-scale re-arrangements of DNA and of molecules associated with combed DNA fibers. Here, we show how CIS may be extended to 13C-labeling via the detection and quantification of the 13C14N- recombinant ion and the use of the 13C:12C ratio, we discuss how CIS might permit three successive labels, and we suggest ideas that might be explored using CIS.
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Hatch, K. A., K. A. Sacksteder, I. W. Treichel, M. E. Cook et W. P. Porter. « Early Detection of Catabolic State via Change in 13C/12C Ratios of Blood Proteins ». Biochemical and Biophysical Research Communications 212, no 3 (juillet 1995) : 719–26. http://dx.doi.org/10.1006/bbrc.1995.2030.

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KINOSHITA, Haruki, Yasuo TOHIRA, Hiroshi SUGIYAMA et Mikio SAWADA. « Use of 13C-NMR Spectroscopy for Detection and Identification of Labile Metabolites of 13C-labeled Inabenfide ». Journal of Pesticide Science 12, no 2 (1987) : 261–63. http://dx.doi.org/10.1584/jpestics.12.261.

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van Wüllen, Leo, et Martin Kalwei. « 13C–27Al TRAPDOR and REDOR Experiments for the Detection of 13C–27Al Dipolar Interactions in Solids ». Journal of Magnetic Resonance 139, no 2 (août 1999) : 250–57. http://dx.doi.org/10.1006/jmre.1999.1765.

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Battistel, Marcos D., et Darón I. Freedberg. « Dispersing the crowd : Adopting 13C direct detection for glycans ». Journal of Magnetic Resonance 318 (septembre 2020) : 106792. http://dx.doi.org/10.1016/j.jmr.2020.106792.

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Andersson, P., J. Sandström, D. Hanstorp, N. D. Gibson, K. Wendt, D. J. Pegg et R. D. Thomas. « Selective detection of 13C by laser photodetachment mass spectrometry ». Nuclear Instruments and Methods in Physics Research Section B : Beam Interactions with Materials and Atoms 266, no 16 (août 2008) : 3667–73. http://dx.doi.org/10.1016/j.nimb.2008.05.126.

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Kono, Hiroyuki, Hikaru Anai, Hisaho Hashimoto et Yuuichi Shimizu. « 13C-detection two-dimensional NMR approaches for cellulose derivatives ». Cellulose 22, no 5 (2 juillet 2015) : 2927–42. http://dx.doi.org/10.1007/s10570-015-0697-9.

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Bertini, Ivano, Isabella C. Felli, Leonardo Gonnelli, Vasantha Kumar M. et Roberta Pierattelli. « 13C Direct-Detection Biomolecular NMR Spectroscopy in Living Cells ». Angewandte Chemie International Edition 50, no 10 (4 février 2011) : 2339–41. http://dx.doi.org/10.1002/anie.201006636.

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Bertini, Ivano, Isabella C. Felli, Leonardo Gonnelli, Vasantha Kumar M. et Roberta Pierattelli. « 13C Direct-Detection Biomolecular NMR Spectroscopy in Living Cells ». Angewandte Chemie 123, no 10 (4 février 2011) : 2387–89. http://dx.doi.org/10.1002/ange.201006636.

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Rapoport, S. I., A. M. Zyakun et Nina A. Shubina. « Breathing tests and their significance in the clinic of internal diseases : the importance of non-invasive 13C bicarbonate breath test in medical diagnostics. » Clinical Medicine (Russian Journal) 96, no 4 (26 septembre 2018) : 309–13. http://dx.doi.org/10.18821/0023-2149-2018-96-4-309-313.

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13C breath tests have been widely developed in the world gastroenterology at the beginning of the 90-ies of the last century. This technique has been used for over 20 years in many developed countries and it has long been a routine and mass procedure. 13C urease breath test for infection Helicobacter pylori detection is the most widely analysis among 13C breath tests. Researchers are developing new 13C-biomarkers and expand the list of available substrates. One of these techniques is a multifunctional 13C bicarbonate breath test. Here is a brief overview of this application.
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Carvalho, R. A., P. Zhao, C. B. Wiegers, F. M. H. Jeffrey, C. R. Malloy et A. D. Sherry. « TCA cycle kinetics in the rat heart by analysis of13C isotopomers using indirect1H[13C] detection ». American Journal of Physiology-Heart and Circulatory Physiology 281, no 3 (1 septembre 2001) : H1413—H1421. http://dx.doi.org/10.1152/ajpheart.2001.281.3.h1413.

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This study was designed to test the hypothesis that indirect1H[13C] detection of tricarboxylic acid (TCA) cycle intermediates using heteronuclear multiple quantum correlation-total correlation spectroscopy (HMQC-TOCSY) nuclear magnetic resonance (NMR) spectroscopy provides additional13C isotopomer information that better describes the kinetic exchanges that occur between intracellular compartments than direct 13C NMR detection. NMR data were collected on extracts of rat hearts perfused at various times with combinations of [2-13C]acetate, propionate, the transaminase inhibitor aminooxyacetate, and 13C multiplet areas derived from spectra of tissue glutamate were fit to a standard kinetic model of the TCA cycle. Although the two NMR methods detect different populations of13C isotopomers, similar values were found for TCA cycle and exchange fluxes by analyzing the two data sets. Perfusion of hearts with unlabeled propionate in addition to [2-13C]acetate resulted in an increase in the pool size of all four-carbon TCA cycle intermediates. This allowed the addition of isotopomer data from aspartate and malate in addition to the more abundant glutamate. This study illustrates that metabolic inhibitors can provide new insights into metabolic transport processes in intact tissues.
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de Graaf, Robin A., Peter B. Brown, Graeme F. Mason, Douglas L. Rothman et Kevin L. Behar. « Detection of [1,6-13C2]-glucose metabolism in rat brain by in vivo1H-[13C]-NMR spectroscopy ». Magnetic Resonance in Medicine 49, no 1 (31 décembre 2002) : 37–46. http://dx.doi.org/10.1002/mrm.10348.

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Brookes, Steven T., Andrew Barrie et Jonathan E. Davies. « A Rapid 13C/12C Test for Determination of Corn Syrups in Honey ». Journal of AOAC INTERNATIONAL 74, no 4 (1 juillet 1991) : 627–29. http://dx.doi.org/10.1093/jaoac/74.4.627.

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Abstract The AOAC official method for detection of corn syrup products in honey measures the 13C/12C ratio (δ13C) (978.17). In the official method, a suspect honey is combusted off-line to C02 gas for analysis on a dual-inlet isotope ratio mass spectrometer (IRMS). The procedure is manual, requires liquid N2, and takes 20-50 min/sample. In the present study, we examine a recently developed alternative, automated 15N 13C analysis mass spectrometry (ANCA-MS). This procedure combusts and analyzes 66 samples in a batch and takes only 5 min/sample. We used both ANCA-MS and IRMS with offline combustion to analyze 6 honeys containing from 0 to 100% high fructose corn syrup (HFCS). δ13C values by both methods agreed within 0.2%o and gave an excellent straight line fit (slope = 0.991; R = 1). As an alternative to IRMS, ANCA-MS is automated and provides a 5-fold increase in sample throughput.
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Wang, Jingzhu, Rui Yang, Wenning Yang, Xin Liu, Yanyi Xing et Youxuan Xu. « IRMS detection of testosterone manipulated with 13C labeled standards in human urine by removing the labeled 13C ». Analytica Chimica Acta 852 (décembre 2014) : 146–52. http://dx.doi.org/10.1016/j.aca.2014.09.007.

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Zetta, Lucia, Antonio De Marco, Clemens Anklin, Mara Cornia et Giovanni Casiraghi. « Structure elucidation of a hexahydrocannabinol derivative via13C13C homonuclear correlation and1H13C heteronuclear correlation with proton detection ». Magnetic Resonance in Chemistry 25, no 12 (décembre 1987) : 1081–83. http://dx.doi.org/10.1002/mrc.1260251213.

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Gallagher, Erin M., Lily Y. Young, Lora M. McGuinness et Lee J. Kerkhof. « Detection of 2,4,6-Trinitrotoluene-Utilizing Anaerobic Bacteria by 15N and 13C Incorporation ». Applied and Environmental Microbiology 76, no 5 (15 janvier 2010) : 1695–98. http://dx.doi.org/10.1128/aem.02274-09.

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ABSTRACT 2,4,6-Trinitrotoluene (15N or 13C labeled) was added to Norfolk Harbor sediments to test whether anaerobic bacteria use TNT for growth. Stable-isotope probing (SIP)-terminal restriction fragment length polymorphism (TRFLP) detected peaks in the [15N]TNT cultures (60, 163, and 168 bp). The 60-bp peak was also present in the [13C]TNT cultures and was related to Lysobacter taiwanensis.
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Guglielmetti, Caroline, Chloé Najac, Alessandro Didonna, Annemie Van der Linden, Sabrina M. Ronen et Myriam M. Chaumeil. « Hyperpolarized 13C MR metabolic imaging can detect neuroinflammation in vivo in a multiple sclerosis murine model ». Proceedings of the National Academy of Sciences 114, no 33 (31 juillet 2017) : E6982—E6991. http://dx.doi.org/10.1073/pnas.1613345114.

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Proinflammatory mononuclear phagocytes (MPs) play a crucial role in the progression of multiple sclerosis (MS) and other neurodegenerative diseases. Despite advances in neuroimaging, there are currently limited available methods enabling noninvasive detection of MPs in vivo. Interestingly, upon activation and subsequent differentiation toward a proinflammatory phenotype MPs undergo metabolic reprogramming that results in increased glycolysis and production of lactate. Hyperpolarized (HP) 13C magnetic resonance spectroscopic imaging (MRSI) is a clinically translatable imaging method that allows noninvasive monitoring of metabolic pathways in real time. This method has proven highly useful to monitor the Warburg effect in cancer, through MR detection of increased HP [1-13C]pyruvate-to-lactate conversion. However, to date, this method has never been applied to the study of neuroinflammation. Here, we questioned the potential of 13C MRSI of HP [1-13C]pyruvate to monitor the presence of neuroinflammatory lesions in vivo in the cuprizone mouse model of MS. First, we demonstrated that 13C MRSI could detect a significant increase in HP [1-13C]pyruvate-to-lactate conversion, which was associated with a high density of proinflammatory MPs. We further demonstrated that the increase in HP [1-13C]lactate was likely mediated by pyruvate dehydrogenase kinase 1 up-regulation in activated MPs, resulting in regional pyruvate dehydrogenase inhibition. Altogether, our results demonstrate a potential for 13C MRSI of HP [1-13C]pyruvate as a neuroimaging method for assessment of inflammatory lesions. This approach could prove useful not only in MS but also in other neurological diseases presenting inflammatory components.
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Krueger, Dana A. « Stable Carbon Isotope Ratio Method For Detection Of Corn-Derived Acetic Acid In Apple Cider Vinegar : Collaborative Study ». Journal of AOAC INTERNATIONAL 75, no 4 (1 juillet 1992) : 725–28. http://dx.doi.org/10.1093/jaoac/75.4.725.

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Abstract The stable carbon isotope ratio analysis method for determining the presence of corn-derived acetic acid in cider vinegar has been collaboratively studied. The method is based upon natural differences in the 13C /12C ratio; pure cider vinegars yield δ13C results near -25 %o, while corn vinegar yields results near -10 %o. Samples are combusted at 500 C in sealed glass tubes over CuO. The purified CO2 is analyzed by isotope ratio mass spectrometry relative to the Pee Dee belemnite limestone (PDB) standard. The precision of this method was observed to be similar to that of other isotope ratio methods that have been collaboratively studied: SR ranged from 0.6 to 1.2, while sr ranged from 0.1 to 1.1. The results indicate that as little as 10% added corn vinegar may be detected in cider vinegar. On the basis of published data of the natural variability of cider vinegar 13C /12C ratios, it is recommended that samples yielding results more positive than -22.0 %o be classified as not pure cider vinegar using this method. This method has been adopted first action by AOAC International.
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Rahaman, Fazlur, Prabhat Gautam, Priti Gupta et Subrata Mondal. « A Simple and Efficient Schiff Base Derived Chemosensor for Selective Detection of Fluoride Ion ». Journal of University of Shanghai for Science and Technology 23, no 09 (14 septembre 2021) : 646–55. http://dx.doi.org/10.51201/jusst/21/09551.

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A new thiazole substituted chemosensor 1 has been designed and synthesized for selective detection of fluoride ions. The chemosensor 1 was characterized by 1H NMR and 13C NMR. The absorption studies of chemosensor in DMF exhibits two peaks at 283 nm and 327 nm. The anion sensing behaviour of chemosensor 1 for various anions (I-, Cl-, Br-, NO3-, HSO4-, PF6-, ClO4-) in DMF were investigated by UV-vis spectroscopy. Chemosensor 1 exhibited high degree of selectivity for fluoride ions over other anions. A good linearity in the range of 16-133 μM with 6.12 μM limit of detection value (LOD) was observed.
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Sriram, Renuka, Jinny Sun, Javier Villanueva-Meyer, Christopher Mutch, Justin De Los Santos, Jason Peters, David E. Korenchan et al. « Detection of Bacteria-Specific Metabolism Using Hyperpolarized [2-13C]Pyruvate ». ACS Infectious Diseases 4, no 5 (6 février 2018) : 797–805. http://dx.doi.org/10.1021/acsinfecdis.7b00234.

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Farès, Christophe, Irene Amata et Teresa Carlomagno. « 13C-Detection in RNA Bases : Revealing Structure−Chemical Shift Relationships ». Journal of the American Chemical Society 129, no 51 (décembre 2007) : 15814–23. http://dx.doi.org/10.1021/ja0727417.

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Pasat, Gabriela, John S. Zintsmaster et Jeffrey W. Peng. « Direct 13C-detection for carbonyl relaxation studies of protein dynamics ». Journal of Magnetic Resonance 193, no 2 (août 2008) : 226–32. http://dx.doi.org/10.1016/j.jmr.2008.05.003.

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Avison, M. J., D. L. Rothman, E. Nadel et R. G. Shulman. « Detection of human muscle glycogen by natural abundance 13C NMR. » Proceedings of the National Academy of Sciences 85, no 5 (1 mars 1988) : 1634–36. http://dx.doi.org/10.1073/pnas.85.5.1634.

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Pratum, T. K., et B. S. Moore. « Inverse Detection of 13C Multiple-Quantum Coherence for Biosynthetic Studies ». Journal of Magnetic Resonance, Series B 102, no 1 (août 1993) : 91–97. http://dx.doi.org/10.1006/jmrb.1993.1067.

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Autry, Adam, Jeremy Gordon, Marisa LaFontaine, Hsin-Yu Chen, Javier Villanueva-Meyer, Susan Chang, Jennifer Clarke et al. « NIMG-50. INITIAL EXPERIENCE : DETECTION OF ABERRANT HYPERPOLARIZED [1-13C]PYRUVATE METABOLISM IN PATIENTS WITH GBM PRIOR TO RESECTION ». Neuro-Oncology 22, Supplement_2 (novembre 2020) : ii159. http://dx.doi.org/10.1093/neuonc/noaa215.663.

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Abstract INTRODUCTION Detecting radiological response or resistance to treatment in patients with GBM is difficult with conventional MRI. In response to this challenge, hyperpolarized carbon-13 (HP-13C) MRI techniques were developed to probe real-time [1-13C]pyruvate metabolism. METHODS Dynamic HP-13C MRI was acquired pre-operatively from 6 patientswith recurrent GBM following intravenous injection of HP [1-13C]pyruvate. Five were confirmed with tumor progression and one had treatment effects without progression. Frequency-selective echo-planar imaging (8 slices, 3s temporal resolution, 3.38 cm3 spatial resolution, 60s acquisition) captured [1-13C]pyruvate metabolism to [1-13C]lactate and [1-13C]bicarbonate in the brain. Proton imaging included 3-D FLAIR, T1-weighted post-Gd IRSPGR, and spectroscopy. Carbon-13 voxels with non-enhancing lesion (NEL) or contrast-enhancing lesion (CEL) were identified for subsequent analysis. Temporally-summed HP-13C metabolite data within the CEL and NEL were evaluated using the pyruvate-to-lactate ratio; a modified ratio that takes into account vascular contributions of pyruvate; and parameter percentile ranks over the entire brain. Proton spectroscopy data were processed to obtain choline-to-NAA index (CNI) maps, which provide z-scores of relative tissue abnormality. RESULTS All of the anatomic lesions displayed abnormal CNI with maximum values of 3.22-6.35. The 5 patients with CEL lesions demonstrated 87th– 98thpercentile levels of pyruvate in the brain; and 95th-100thpercentile levels of lactate in 4 progressed patients and 60thpercentile in the patient presenting with treatment effects. For the patient with an exclusively non-enhancing lesion, percentile levels of pyruvate and lactate were 66thand 88thin the brain, respectively. The mean+/-SD percentile of the lactate-to-pyruvate and modified ratios were 75+/-22, 86+/-23 and 60+/-3, 71+/-12 in the progressed and non-progressed patients, respectively. CONCLUSION These data importantly demonstrate aberrant [1-13C]pyruvate metabolism in patients with GBM in both contrast-enhancing and non-enhancing lesions. Ongoing studies will further characterize the utility of HP imaging markers.
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Coleman, WM. « A Study of the Reaction Between Quinone and 2R4F Cigarette Smoke Condensate ». Beiträge zur Tabakforschung International/Contributions to Tobacco Research 23, no 6 (1 décembre 2009) : 359–67. http://dx.doi.org/10.2478/cttr-2013-0870.

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AbstractA study using atomic emission detection (AED) as an approach to explore the fate of quinone added into 2R4F cigarette smoke condensate (CSC) have been performed. Both natural isotope quinone and 13C labeled quinone were used in the study. When coupled with a gas chromatographic separation (GC/AED), the AED provided informative new data on 13C isotope enriched products generated following reactions between 2R4F CSC and the quinone. Two 13C containing species were detected by GC/AED. Matching chromatographic separation using gas chromatography/mass selective detection (GC/MSD) allowed for a structural assignment of a relatively minor CSC 13C 6quinone reaction product as nitrohydroquinone (13C6NO2HQ). The chemical mechanism accounting for the formation of 13C6NO2HQ in the CSC was envisioned to be a reaction product between HONO and 13C 6Quinone (13C6Q) to form 13C6NO2Q, followed by reduction of 13C6NO2Q to 13C6NO2HQ. The amount of 13C6NO2HQ accounted for ~6% of the added 13C6Q. Identical trends in reaction chemistries were found for experiments with 12C6Q. The major reaction product detected upon addition of 13C6Q to the 2R4F CSC sample was 13C6HQ. 13C6HQ accounted for, on average, ~47% of the initial 13C6Q concentration. Identical trends in reaction chemistries were found for experiments with 12C6Q. No additional 13C containing species were detected. A 13C AED compound independent calibration (CIC) approach under the operating conditions was not possible. This work further expands the knowledge regarding possible reactions of quinone and hydroquinone in CSC.
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Li, Shizhe, Yan Zhang, Maria Ferraris Araneta, Yun Xiang, Christopher Johnson, Robert B. Innis et Jun Shen. « In vivo detection of 13C isotopomer turnover in the human brain by sequential infusion of 13C labeled substrates ». Journal of Magnetic Resonance 218 (mai 2012) : 16–21. http://dx.doi.org/10.1016/j.jmr.2012.03.012.

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Casieri, C., A. Knijn, F. Podo et F. De Luca. « 1H NMR detection of 13C–1H bonds by double 13C editing : application to the discrimination of glucose metabolites ». Chemical Physics Letters 338, no 2-3 (avril 2001) : 137–41. http://dx.doi.org/10.1016/s0009-2614(01)00258-5.

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Zhang, Xiulin, Cunlong Wang, Yang He, Jin Xing, Yan He, Xueyun Huo, Rui Fu et al. « Establishment of Noninvasive Methods for the Detection of Helicobacter pylori in Mongolian Gerbils and Application of Main Laboratory Gerbil Populations in China ». BioMed Research International 2022 (29 mars 2022) : 1–11. http://dx.doi.org/10.1155/2022/6036457.

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Identifying Helicobacter pylori (H. pylori, Hp) infection in animals before and after artificial infection influences the subsequent experiment. We established effective and noninvasive detection methods, including the gastric fluid nested polymerase chain reaction (PCR) method and the 13C-urea breath test, which can detect Hp before modeling Hp infection in Mongolian gerbils. We designed a gas collection equipment for gerbils. Hp nested PCR was also performed on gastric fluid, gastric mucosa, duodenal contents, and faeces of gerbils challenged with Hp. Conventional Hp detection methods, including rapid urease assay and immunohistochemistry, were compared. Moreover, we assessed the natural infection of Hp in 135 gerbils that had never been exposed to Hp artificially from the major laboratory gerbil groups in China. In 10 Hp infected gerbils, the positive detection results were 100%, 100%, 90%, and 10% in gastric fluid, gastric mucosa, duodenal contents, and faeces with nested PCR, respectively. A rapid urease test performed on gastric mucosa showed that all animals were infected with Hp. Immunohistochemical detection and bacteria culture of gastric mucosa samples that were positive by the nested PCR method also confirmed the presence of Hp. 9% (3/35) and 6% (2/31) natural infection rates were found in conventional gerbil groups from the Capital Medical University and Zhejiang Laboratory Animal Center. In conclusion, we established two noninvasive Hp detection methods that can be performed before modelingHp infection, including the gastric fluid nested PCR method and the 13C-urea breath test.
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Thomas, J. N., T. L. Johnston, I. M. Litvak, V. Ramaswamy, M. E. Merritt, J. R. Rocca, A. S. Edison et W. W. Brey. « Implementing High Q-Factor HTS Resonators to Enhance Probe Sensitivity in 13C NMR Spectroscopy ». Journal of Physics : Conference Series 2323, no 1 (1 août 2022) : 012030. http://dx.doi.org/10.1088/1742-6596/2323/1/012030.

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Abstract Nuclear magnetic resonance spectroscopy (NMR) probes using thin-film high temperature superconducting (HTS) resonators provide exceptional mass sensitivity in small-sample NMR experiments for natural products chemistry and metabolomics. We report improvements in sensitivity to our 1.5 mm 13C-optimized NMR probe based on HTS resonators. The probe has a sample volume of 35 microliters and operates in a 14.1 T magnet. The probe also features HTS resonators for 1H transmission and detection and the 2H lock. The probe utilizes a 13C resonator design that provides greater efficiency than our previous design. The quality factor of the new resonator in the 14.1 T background field was measured to be 4,300, which is over 3x the value of the previous design. To effectively implement the improved quality factor, we demonstrate the effect of adding a shorted transmission line stub to increase the bandwidth and reduce the rise/fall time of 13C irradiation pulses. Initial NMR measurements verify 13C NMR sensitivity is significantly improved while preserving detection bandwidth. The probe will be used for applications in metabolomics.
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Feith, André, Attila Teleki, Michaela Graf, Lorenzo Favilli et Ralf Takors. « HILIC-Enabled 13C Metabolomics Strategies : Comparing Quantitative Precision and Spectral Accuracy of QTOF High- and QQQ Low-Resolution Mass Spectrometry ». Metabolites 9, no 4 (2 avril 2019) : 63. http://dx.doi.org/10.3390/metabo9040063.

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Dynamic 13C-tracer-based flux analyses of in vivo reaction networks still require a continuous development of advanced quantification methods applying state-of-the-art mass spectrometry platforms. Utilizing alkaline HILIC chromatography, we adapt strategies for a systematic quantification study in non- and 13C-labeled multicomponent endogenous Corynebacterium glutamicum extracts by LC-QTOF high resolution (HRMS) and LC-QQQ tandem mass spectrometry (MS/MS). Without prior derivatization, a representative cross-section of 17 central carbon and anabolic key intermediates were analyzed with high selectivity and sensitivity under optimized ESI-MS settings. In column detection limits for the absolute quantification range were between 6.8–304.7 (QQQ) and 28.7–881.5 fmol (QTOF) with comparable linearities (3–5 orders of magnitude) and enhanced precision using QQQ-MRM detection. Tailor-made preparations of uniformly (U)13C-labeled cultivation extracts for isotope dilution mass spectrometry enabled the accurate quantification in complex sample matrices and extended linearities without effect on method parameters. Furthermore, evaluation of metabolite-specific m+1-to-m+0 ratios (ISR1:0) in non-labeled extracts exhibited sufficient methodical spectral accuracies with mean deviations of 3.89 ± 3.54% (QTOF) and 4.01 ± 3.01% (QQQ). Based on the excellent HILIC performance, conformity analysis of time-resolved isotopic enrichments in 13C-tracer experiments revealed sufficient spectral accuracy for QQQ-SIM detection. However, only QTOF-HRMS ensures determination of the full isotopologue space in complex matrices without mass interferences.
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Cabezas, C., E. Roueff, B. Tercero, M. Agúndez, N. Marcelino, P. de Vicente et J. Cernicharo. « Detection of deuterated methylcyanoacetylene, CH2DC3N, in TMC-1 ». Astronomy & ; Astrophysics 650 (juin 2021) : L15. http://dx.doi.org/10.1051/0004-6361/202141371.

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We report the first detection in space of the single deuterated isotopologue of methylcyanoacetylene, CH2DC3N. A total of 15 rotational transitions, with J = 8–12 and Ka = 0 and 1, were identified for this species in TMC-1 in the 31.0–50.4 GHz range using the Yebes 40 m radio telescope. The observed frequencies were used to derive for the first time the spectroscopic parameters of this deuterated isotopologue. We derive a column density of (8.0 ± 0.4)×1010 cm−2. The abundance ratio of CH3C3N to CH2DC3N is ∼22. We also theoretically computed the principal spectroscopic constants of 13C isotopologues of CH3C3N and CH3C4H and those of the deuterated isotopologues of CH3C4H for which we could expect a similar degree of deuteration enhancement. However, we have not detected either CH2DC4H or CH3C4D, nor any 13C isotopologues. The different observed deuterium ratios in TMC-1 are reasonably accounted for by a gas-phase chemical model where the low temperature conditions favour deuteron transfer through reactions with H2D+.
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Wrackmeyer, Bernd, Roland Köster et Günter Seidel. « Notizen : Tricarbonyliron Complexes - Observation of 13C(CO) NMR Signals via Polarization Transfer ». Zeitschrift für Naturforschung B 50, no 7 (1 juillet 1995) : 1127–29. http://dx.doi.org/10.1515/znb-1995-0726.

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Improvements in the detection of 13C(CO) resonances by using polarization transfer techniques, based on long-range coupling constants nJ(13C(CO)1H) = 1 ±0.1 Hz (n > 3), are reported. Coupling constants between 13C(CO) and other rare spin-1/2 nuclei have been observed, and longrange 13C(CO)-1H coupling have been traced by two-dimensional (2D ) 13C/1H heteronuclear shift correlations (HETCOR). Seven tricarbonyliron complexes 1 to 5 serve as examples in which the [Fe(CO)3] fragment is linked to cyclic dienes (siloles: 1a, b; 1,1′-spirobisilole: 2), and to cyclic heterodienes derived from substituted 2,5-dihydro- 2,5-silaboroles [1-aza (3a, b); 1-thia (4); 1-selena (5)]. In the case of complex 5, it was possible to resolve the 77Se satellites with 2J( 77Se13C(CO )) = 4.4 Hz. In 2D 13C (CO )/1H HETCOR experiments it was shown that polarization transfer originates mainly from C-methyl groups [4J( 13C(CO)/1H (M ))], adjacent to the “terminal” carbon atom(s) of the cyclic diene or heterodiene system which are linked to the [Fe(CO)3] fragment.
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