Boyao Zhang


Last Name

Zhang

First Name

Boyao

ORCID

0000-0002-2856-9376

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2023 - 20252
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Publications 1 - 2 of 2
  • Systematic Study of Bacterial Carcinogen Metabolism and its Functional Consequences in Chemical Carcinogenesis
    Item type: Doctoral Thesis
    Zhang, Boyao (2023)
    Exogenous chemicals (‘xenobiotics’) that humans are exposed to can accumulate in our body, interact with our cells in various ways, and potentially result in health problems. The level of accumulation of xenobiotics and the way they accumulate primarily depend on the biochemical modifications of xenobiotics by biological agents such as enzymes (‘biotransformation’) in our body. Different enzymatic reactions can lead to the production of harmful or harmless metabolites, which can subsequently affect how easily the xenobiotics can be eliminated from our body. Previous studies have extensively researched the role of human enzymes in xenobiotic metabolism. However, the role of the human microbiota in metabolizing xenobiotics is less well known. Importantly, it has been shown that there are at least 100-fold more enzymes encoded by an individual’s microbiome compared to the human genome, suggesting that they might also contribute to the metabolic fates of xenobiotics in the human body. Previous studies have shown that gut bacteria contribute to metabolism of synthetic chemicals (e.g. dyes containing azo bonds), clinical drugs (e.g. diltiazem by Bacteroides thetaiotaomicron) and food molecules (e.g. daidzein by Eggerthellaceae strains). However, there is a knowledge gap in how significant such bacterial-mediated metabolism is on a systemic level and how host and bacterial xenobiotic metabolism interact with one another. The primary focus of my PhD is therefore to systematically investigate the metabolism of xenobiotics by bacteria colonizing the human gastrointestinal tract. Particularly, I have selected xenobiotics that are previously known to be potentially carcinogenic and/or mutagenic, which in turn allowed me to investigate the functional consequences of bacteria-mediated xenobiotic biotransformation with respect to cancer development in mouse models. The results of my thesis provide the basis for future research aiming at harnessing the metabolic potential of the microbiota for preventing chemically induced carcinogenesis.
  • Is cardiopulmonary transit time (CPTT) measured by using dynamic rubidium cardiac PET/CT a predictor for cardiac function?
    Item type: Journal Article
    Seige, Lena C.; Zhang, Boyao; Heimer, Jakob; et al. (2025)
    The International Journal of Cardiovascular Imaging
    Cardiopulmonary transit time (CPTT) represents the time needed for the circulation of blood from the right to the left ventricle. This parameter can be measured during dynamic acquisition of rubidium ([82Rb]) cardiac PET/CT. To further characterize this marker, we wanted to assess the association between CPTT and parameters of cardiac function derived from echocardiography. Retrospective single center analysis of patients referred to [82Rb]RbCl-PET/CT with rest/stress protocol on an integrated hybrid PET/CT system (Biograph mCT, Siemens Healthineers, Erlangen, Germany) and echocardiography within 100 days. After intravenous injection of 7.5 MBq/kg [82Rb]RbCl dynamic scans with initially 12 x 10 s frames were started. For data analysis a volume of interest (VOI) was drawn in the left and right ventricle using dedicated software. The difference between the peak time for the two time activity curves (TAC) was extracted as CPTT and normalized for heart rate (NCPTT). Associations between NCPTT and echo parameters such as left ventricular ejection fraction (EFEcho) were analyzed using linear regression models. 44 patients (sex: 28 male, 16 female) were enrolled with a time difference between PET and echocardiography of 19.65 +/- 23.3 days. 9 patients had a rest CPTT of 0 s, 32 patients 10 s and 3 patients 20 s. The association between EFEcho and NCPTT revealed a significant negative correlation (beta = -0.77; CI: -1.32, -0.22; p = 0.007). Given this association, univariate predictive models for EFEcho were applied. Root mean square error was 6.83% for the EFPET, and 6.0% for NCPTT, which indicates a slightly higher predictive performance for the NCPTT model with a lower error. Pulmonary transit time can be estimated with [82Rb]RbCl-PET/CT, with a high positive association to rest EFEcho. However, smaller time frames than 10 s are needed, for more accurate estimation of cardiac function.
Publications 1 - 2 of 2