Abstract A20: Dietary ingestion of aristolochic acid: Mechanisms of exposure

Aristolochic acids (AA) are human carcinogens and nephrotoxins found in Aristolochia plants, including herbs used in traditional medicines throughout the world. Aristolochic acids can also be ingested as an environmental contaminant in food, which forms the basis of Balkan endemic nephropathy and associated upper tract urothelial cancer. Aristolactam DNA-adducts, formed after metabolism of AA, are promutagenic and are resistant to repair and readily detected in human tissue sample DNA decades after exposure. Thus, AL-DNA adducts are excellent biomarkers of exposure to this carcinogen. The mutational signature of AA is distinct for an environmental carcinogen and is recognized as Signature 22 in the COSMIC mutational signature database. Molecular epidemiology using the presence of adducts and/or the presence of Signature 22 has implicated AA in the etiology of several cancers, including upper-tract urothelial cancer, bladder cancer, renal cell clear cell carcinoma, hepatocellular carcinoma, and cholangiocarcinomas. In regions of the world reliant on traditional medicines, including much of Asia, the AA contribution to incidence of these cancers is significant. In the Balkan countries of Europe, the route of exposure is thought to occur via contamination of wheat harvests with Aristolochia plant material from weed growth. In endemic villages farming families traditionally have ingested primarily wheat flour milled from their own harvests. An alternative hypothesis is that decaying Aristolochia plants release the chemically stable aristolochic acids into the soil, and these are then taken up and concentrated by food plants. To distinguish between these hypotheses, we have obtained 25 flour samples from individual farms along the Croatia/Bosnia and Herzegovina border. To identify AA-contaminated flour, aristolochic acids were extracted from aliquots of the flour, reduced to aristolactams, and quantitated with an LC-ESI-MS/MS method. Several flour samples were indeed contaminated with AA in the range of 10–100 parts per billion. Secondly, we also extracted DNA from each flour sample. The direct contamination hypothesis predicts the presence of Aristolochia DNA in contaminated flour samples; the indirect contamination via decay hypothesis does not. Using widely accepted plant “barcode” PCR protocols, we amplified a portion of the rbcLa gene with generic primers that amplify the gene from all species. Within this PCR amplicon each plant species has a constellation of specific base-pairs. Thus, the contribution of all plant species to the flour sample can be determined by highly parallel sequencing of the amplicon. We will present the results of this next-gen sequencing to determine the contribution of Aristolochia to Balkan flour samples and correlation with aristolochic acid content.

Citation Format: Viktoriya Sidorenko, Robert Rieger, Bojan Jelakovic, Thomas Rosenquist. Dietary ingestion of aristolochic acid: Mechanisms of exposure [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr A20.

Performance of the BM@N GEM/CSC tracking system at the Nuclotron beam

BM@N (Baryonic Matter at the Nuclotron) is a fixed target experiment aimed to study nuclear matter in the relativistic heavy-ion collisions at the Nuclotron accelerator in JINR. The BM@N tracking system is based on Gas Electron Multipliers (GEM) detectors mounted inside the BM@N analyzing magnet. The Cathode Strip Chamber (CSC) is installed outside the magnet. The CSC is used for improvement of particles momentum identification. The structure of the GEM detectors and the CSC prototype and the results of study of their characteristics are presented. The GEM detectors and CSC are integrated into the BM@N experimental setup and data acquisition system. The results of first tests of the GEM tracking system and CSC in last runs are shortly reviewed.

Account for uncertainties of control measurements in the assessment of design margin factors

This paper considers two interrelated issues and – proceeding from the conditional probability concept and Bayes’ statistical theorem – suggests a universal method to process measured data with account of prior information available. To assure reliable reactor operation, at the design stage it is suggested to account for errors of subsequent control measurements while assessing the engineering margin factors for reactor parameters to be measured.

Biomonitoring of aristolactam-DNA adducts in human tissues using ultra-performance liquid chromatography/ion-trap mass spectrometry

Aristolochic acids (AAs) are a structurally related family of nephrotoxic and carcinogenic nitrophenanthrene compounds found in Aristolochia herbaceous plants, many of which have been used worldwide for medicinal purposes. AAs have been implicated in the etiology of so-called Chinese herbs nephropathy and of Balkan endemic nephropathy. Both of these disease syndromes are associated with carcinomas of the upper urinary tract (UUC). 8-Methoxy-6-nitrophenanthro-[3,4-d]-1,3-dioxolo-5-carboxylic acid (AA-I) is a principal component of Aristolochia herbs. Following metabolic activation, AA-I reacts with DNA to form aristolactam (AL-I)-DNA adducts. We have developed a sensitive analytical method, using ultraperformance liquid chromatography-electrospray ionization/multistage mass spectrometry (UPLC-ESI/MS(n)) with a linear quadrupole ion-trap mass spectrometer, to measure 7-(deoxyadenosin-N(6)-yl) aristolactam I (dA-AL-I) and 7-(deoxyguanosin-N(2)-yl) aristolactam I (dG-AL-I) adducts. Using 10 μg of DNA for measurements, the lower limits of quantitation of dA-AL-I and dG-AL-I are, respectively, 0.3 and 1.0 adducts per 10(8) DNA bases. We have used UPLC-ESI/MS(n) to quantify AL-DNA adducts in tissues of rodents exposed to AA and in the renal cortex of patients with UUC who reside in Taiwan, where the incidence of this uncommon cancer is the highest reported for any country in the world. In human tissues, dA-AL-I was detected at levels ranging from 9 to 338 adducts per 10(8) DNA bases, whereas dG-AL-I was not found. We conclude that UPLC-ESI/MS(n) is a highly sensitive, specific and robust analytical method, positioned to supplant (32)P-postlabeling techniques currently used for biomonitoring of DNA adducts in human tissues. Importantly, UPLC-ESI/MS(n) could be used to document exposure to AA, the toxicant responsible for AA nephropathy and its associated UUC.