Imaging bacterial infection using deuterium-enriched sugar alcohols.

项目总结： 该应用解决了放射科医生和其他内科医生经常遇到的主要挑战， 即将活动性感染与人体内其他过程区分开来。为了应对这一挑战， 我们的实验室开发了超极化13C磁共振成像和正电子发射断层扫描(PET)工具 针对细菌特有的新陈代谢。在这项提议中，我们使用了另一种核磁共振 (核磁共振)-可观察到的稳定同位素，即氢(2H)，用于检测体外和体内的活微生物 活着。在此过程中，我们通过(1)识别2H磁共振成像(MRI) 2H MRI-可观察到的代谢物，具有与HDO(水)所需的化学位移分离和(2)使用 细菌特有的糖醇，与微生物结合不易饱和。我们的方法 还利用两种不同的策略以微生物特有的方式整合2H，并新 开发了2H MRI方法，以最大限度地提高灵敏度。 所采用的两种检测策略是(1)将2H底物转换为主要的2H-MRI 可观察到的下游代谢物或(2)2H底物转化为死端代谢物，即 积累为2H-MRI可检测的物种。丰富的变体突出了这两个概念 山梨醇，D-[6，6‘-2H2]山梨醇，其代谢可通过其转化为乳酸/乙醇来检测，或 2-脱氧-D-[2，2‘-2H2]山梨醇预计会以其6-磷酸化加合物的形式被“捕获”在细菌中。在这两个地方 例如，在活体2H磁共振成像中，2H核具有所需的化学位移。此外，这些技术 我们的长期目标是将无毒的2H糖醇应用于 包括儿童在内的弱势群体，不需要电离辐射。我们将首先改编一个核磁共振- 用于体外研究细菌中2H底物代谢的兼容生物反应器(特定目标1)。 然后我们将展示使用浓缩底物对2H进行细菌特异性掺入的情况，这些底物可以是 代谢成主要的2H-MRI可检测产物，或被病原体保留为死端分子 (具体目标2)。在特定的目标3中，我们将展示使用这些工具在14T时的2H MRI可以检测到生命 体内的细菌。

PROJECT SUMMARY: This application addresses a major challenge that radiologists and other physicians encounter frequently, namely distinguishing active infection from other processes in the human body. In response to this challenge, our laboratory has developed both hyperpolarized 13C MRI and positron emission tomography (PET) tools targeting bacteria-specific metabolism. In this proposal, we employ another nuclear magnetic resonance (NMR)-observable stable isotope namely deuterium (2H) to detect living microorganisms both in vitro and in vivo. In doing so we address two major challenges of 2H magnetic resonance imaging (MRI) by (1) identifying 2H MRI-observable metabolites that have the needed chemical shift separation from HDO (water) and (2) using bacteria-specific sugar alcohols whose incorporation into microorganisms is not easily saturated. Our approach also takes advantage of two different strategies to incorporate 2H in a microorganism-specific way, and newly developed 2H MRI methods to maximize sensitivity. The two detection strategies pursued are either (1) a 2H substrate is converted to a dominant, 2H-MRI observable downstream metabolite or (2) a 2H substrate is converted to a dead-end metabolite that is accumulated as a 2H-MRI detectable species. These two concepts are highlighted by enriched variants of sorbitol, either D-[6,6'-2H2]sorbitol whose metabolism may be detected by its conversion to lactate/ethanol, or 2-deoxy-D-[2,2'-2H2]sorbitol anticipated to be “trapped” as its 6-phosphorylated adduct in bacteria. In both cases, the 2H nuclei have the needed chemical shift for in vivo 2H MRI imaging. In addition, the technologies pursued are amenable to clinical translation; our long-term goal is application of nontoxic 2H sugar alcohols to vulnerable populations including children, without the need for ionizing radiation. We will first adapt an NMR- compatible bioreactor for use in investigating 2H substrate metabolism in bacteria in vitro (Specific Aim 1). We will show then show bacteria-specific incorporation of 2H using enriched substrates, that are either metabolized to dominant 2H-MRI detectable products, or retained as dead-end molecules by pathogens (Specific Aim 2). In Specific Aim 3, we will show that 2H MRI at 14T using these tools can detect living bacteria in vivo.