Evaluation of commercially available reagents as a reference material for intramolecular carbon isotopic measurements of acetic acid.

RATIONALE: Recent advances in analytical techniques for the intramolecular carbon isotopic ratio measurement of some organic compounds have provided important information on carbon cycles in biochemistry, organic geochemistry and food chemistry. These advances have made it necessary to prepare intramolecular isotopic reference materials (RMs) to use for inter-laboratory calibration and/or inter-calibration among different analytical methods. METHODS: We evaluated the feasibility of preparing RMs using commercially available reagents for intramolecular carbon isotopic ratio measurement of acetic acid. The intramolecular carbon isotopic distribution of nine acetic acid and four sodium acetate reagents was determined with high precision using off-line pyrolysis combined with gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). We also evaluated the potential alteration in the isotopic signature of acetic acid reagents by evaporation. RESULTS: The intramolecular carbon isotopic distributions for the acetic acid and sodium acetate reagents were determined with a precision of better than 0.45‰. We found that the isotopic values of these reagents spanned the carbon isotopic range of acetic acid in biological and environmental samples. We also found that the isotope fractionation associated with the evaporation of acetic acid occurs solely on the methyl position, the carboxyl position being unaffected. CONCLUSIONS: These commercially available reagents will be used as RMs in the future for inter-laboratory calibration and/or inter-calibration with another intramolecular isotopic measurement technique, namely quantitative (13) C NMR. In cases where acetic acid is being used as a RM, its storage must be carefully controlled to prevent evaporation.

A culture method with berbamine, a plant alkaloid, enhances CAR-T cell efficacy through modulating cellular metabolism.

Memory T cells demonstrate superior in vivo persistence and antitumor efficacy. However, methods for manufacturing less differentiated T cells are not yet well-established. Here, we show that producing chimeric antigen receptor (CAR)-T cells using berbamine (BBM), a natural compound found in the Chinese herbal medicine Berberis amurensis, enhances the antitumor efficacy of CAR-T cells. BBM is identified through cell-based screening of chemical compounds using induced pluripotent stem cell-derived T cells, leading to improved viability with a memory T cell phenotype. Transcriptomics and metabolomics using stem cell memory T cells reveal that BBM broadly enhances lipid metabolism. Furthermore, the addition of BBM downregulates the phosphorylation of p38 mitogen-activated protein kinase and enhanced mitochondrial respiration. CD19-CAR-T cells cultured with BBM also extend the survival of leukaemia mouse models due to their superior in vivo persistence. This technology offers a straightforward approach to enhancing the antitumor efficacy of CAR-T cells.

Comparison of IRMS and NMR spectrometry for the determination of intramolecular 13C isotope composition: application to ethanol.

Isotopic (13)C NMR is a relatively recent technique which allows the determination of intramolecular (13)C isotope composition at natural abundance. It has been used in various scientific fields such as authentication, counterfeiting or plant metabolism. Although its precision has already been evaluated, the determination of its trueness remains still challenging. To deal with that issue, a comparison with another normalized technique must be achieved. In this work, we compare the intramolecular (13)C isotope distribution of ethanol from different origins obtained using both Isotope Ratio Mass Spectrometry (IRMS) and Nuclear Magnetic Resonance (NMR) spectrometry techniques. The IRMS approach consists of the oxidation of ethanol to acetic acid followed by the degradation of the latter for the analysis of each fragments formed. We show here that the oxidation of ethanol to acetic acid does not bring any significant error on the determination of the site-specific δ(13)C (δ(13)C(i)) of ethanol using the IRMS approach. The difference between the data obtained for 16 samples from different origins using IRMS and NMR approaches is not statistically significant and remains below 0.3‰. These results are encouraging for the future studies using isotopic NMR, especially in combination with the IRMS approach.