Takamasa Ishikawa

Differential Metabolomics Reveals Ophthalmic Acid as an Oxidative Stress Biomarker Indicating Hepatic Glutathione Consumption

Metabolomics is an emerging tool that can be used to gain insights into cellular and physiological responses. Here we present a metabolome differential display method based on capillary electrophoresis time-of-flight mass spectrometry to profile liver metabolites following acetaminophen-induced hepatotoxicity. We globally detected 1,859 peaks in mouse liver extracts and highlighted multiple changes in metabolite levels, including an activation of the ophthalmate biosynthesis pathway. We confirmed that ophthalmate was synthesized from 2-aminobutyrate through consecutive reactions with γ-glutamylcysteine and glutathione synthetase. Changes in ophthalmate level in mouse serum and liver extracts were closely correlated and ophthalmate levels increased significantly in conjunction with glutathione consumption. Overall, our results provide a broad picture of hepatic metabolite changes following acetaminophen treatment. In addition, we specifically found that serum ophthalmate is a sensitive indicator of hepatic GSH depletion, and may be a new biomarker for oxidative stress. Our method can thus pinpoint specific metabolite changes and provide insights into the perturbation of metabolic pathways on a large scale and serve as a powerful new tool for discovering low molecular weight biomarkers.

Differential metabolomics software for capillary electrophoresis-mass spectrometry data analysis

In metabolomics, the rapid identification of quantitative differences between multiple biological samples remains a major challenge. While capillary electrophoresis–mass spectrometry (CE–MS) is a powerful tool to simultaneously quantify charged metabolites, reliable and easy-to-use software that is well suited to analyze CE–MS metabolic profiles is still lacking. Optimized software tools for CE–MS are needed because of the sometimes large variation in migration time between runs and the wider variety of peak shapes in CE–MS data compared with LC–MS or GC–MS. Therefore, we implemented a stand-alone application named JDAMP (Java application for Differential Analysis of Metabolite Profiles), which allows users to identify the metabolites that vary between two groups. The main features include fast calculation modules and a file converter using an original compact file format, baseline subtraction, dataset normalization and alignment, visualization on 2D plots (m/z and time axis) with matching metabolite standards, and the detection of significant differences between metabolite profiles. Moreover, it features an easy-to-use graphical user interface that requires only a few mouse-actions to complete the analysis. The interface also enables the analyst to evaluate the semiautomatic processes and interactively tune options and parameters depending on the input datasets. The confirmation of findings is available as a list of overlaid electropherograms, which is ranked using a novel difference-evaluation function that accounts for peak size and distortion as well as statistical criteria for accurate difference-detection. Overall, the JDAMP software complements other metabolomics data processing tools and permits easy and rapid detection of significant differences between multiple complex CE–MS profiles.

Global metabolic reprogramming of colorectal cancer occurs at adenoma stage and is induced by MYC

Significance Metabolic reprogramming is one of the hallmarks of cancer. However, the underlying mechanisms that regulate cancer metabolism are poorly understood. Here we performed multiomics-based analysis of paired normal–tumor tissues from patients with colorectal cancer, which revealed that the protooncogene protein MYC regulated global metabolic reprogramming of colorectal cancer by modulating 215 metabolic reactions. Importantly, this metabolic reprogramming occurred in a manner not associated with specific gene mutations in colorectal carcinogenesis. For many years, small-molecule or biologic inhibitors of MYC have been required. Here we demonstrate that knockdown of MYC downstream pyrimidine synthesis genes contributes to the suppression of colorectal cancer cell proliferation similar to MYC, and thus pyrimidine synthesis pathways could be potential targets for colorectal cancer therapy. Cancer cells alter their metabolism for the production of precursors of macromolecules. However, the control mechanisms underlying this reprogramming are poorly understood. Here we show that metabolic reprogramming of colorectal cancer is caused chiefly by aberrant MYC expression. Multiomics-based analyses of paired normal and tumor tissues from 275 patients with colorectal cancer revealed that metabolic alterations occur at the adenoma stage of carcinogenesis, in a manner not associated with specific gene mutations involved in colorectal carcinogenesis. MYC expression induced at least 215 metabolic reactions by changing the expression levels of 121 metabolic genes and 39 transporter genes. Further, MYC negatively regulated the expression of genes involved in mitochondrial biogenesis and maintenance but positively regulated genes involved in DNA and histone methylation. Knockdown of MYC in colorectal cancer cells reset the altered metabolism and suppressed cell growth. Moreover, inhibition of MYC target pyrimidine synthesis genes such as CAD, UMPS, and CTPS blocked cell growth, and thus are potential targets for colorectal cancer therapy.

Synthetic Biomarker Design by Using Analyte-Responsive Acetaminophen

The use of synthetic biomarkers is an emerging technique to improve disease diagnosis. Here, we report a novel design strategy that uses analyte‐responsive acetaminophen (APAP) to expand the catalogue of analytes available for synthetic biomarker development. As proof‐of‐concept, we designed hydrogen peroxide (H2O2)‐responsive APAP (HR‐APAP) and succeeded in H2O2 detection with cellular and animal experiments. In fact, for blood samples following HR‐APAP injection, we demonstrated that the plasma concentration ratio [APAP+APAP conjugates]/[HR‐APAP] accurately reflects in vivo differences in H2O2 levels. We anticipate that our practical methodology will be broadly useful for the preparation of various synthetic biomarkers.

Lifetime measurement of H-4 (Lambda) hypernucleus

Abstract Results are reported on a lifetime measurement of Λ4H formed in 4He (stopped K−,π°) reaction. Decay of Λ4H was clearly identified by observing the monochromatic π− peak from the two-body decay ( Λ 4 H → 4 He + π − p x =132.9 MeV/c ). The lifetime of Λ4H was determined to be τ(Λ4H) = 194−26+24 ps from a distribution of time difference between the K− injection and π− emission.

A measurement of the π0 decay of Λ 12 C and Λ 11 B hypernucleihypernuclei@@@Иэмерения π0 распада гиперядер Λ 12 C и Λ 11 B

SummaryWe made a direct measurement of the π0 weak decay branching ratio of theΛ12C hypernucleus for the first time. The branching ratio is estimated to beΓπ0/Γ=0.166±0.055 from the measurement. The branching ratio agrees fairly with a theoretical calculation with a realistic pion distorted wave function, but is inconsistent with a calculation with a free π0 wave function. An upper limit of the π0 decay branching ratio of theΛ11B hypernucleus was also estimated to beΓπ0/Γ<0.291 (90% confidence level).RiassuntoÈ stata misurata direttamente la frazione di decadimento (debole) dell’ipernucleoΛ12C in π0 per la prima volta. Dalla misura risulta cheΓπ0/Γ=0.166±0.055. Il rapporto coincide con il calcolo teorico con una funzione d’onda distorta realistica pionica, ma non è in accordo con il calcolo con la funzione d’onda libera del pione. Anche il limite superiore stimato del rapporto di decadimento pionico dell’ipernucleoΛ11B èΓπ0/Γ<0.291 (livello di confidenza 90%).РеэюмеВпервые проводится прямое иэмерение отнощение ветвей π0 слабого распада гиперядерΛ12C. Иэ иэмерения оценивается отнощение ветвей, которое составляетΓπ0/Γ=0.166±0.055. Отнощение ветвей совпадает с теоретическим расчетом, испольэуюшим искаженную волновую функцию реального пиона, но не согласуется с вычислением для волновой функции свободного π0. Также оценивается верхний предел отнощения ветвей π0 распада гиперядраΛ11B, который составляетΓπ0/Γ<0.291 (с достоверностью 95%).