Imaging bacterial infection using deuterium-enriched sugar alcohols.

项目概要： 该应用解决了放射科医生和其他医生经常遇到的一个主要挑战， 即区分活动性感染与人体内的其他过程。为了应对这一挑战， 我们的实验室开发了超极化13 C MRI和正电子发射断层扫描（PET）工具 靶向细菌特异性代谢。在这个提议中，我们使用了另一种核磁共振技术， （NMR）-可观察到的稳定同位素，即氘（2 H），用于检测体外和体内的活微生物。 vivo.在此过程中，我们通过以下方式解决2 H磁共振成像（MRI）的两个主要挑战：（1）识别 2 H MRI可观察代谢物，其具有与HDO（水）的所需化学位移分离，和（2）使用 细菌特异性糖醇，其掺入微生物中不容易饱和。我们的方法 还利用两种不同的策略，以微生物特异性的方式结合2 H， 开发了2 H MRI方法，以最大限度地提高灵敏度。 所追求的两种检测策略是（1）将2 H底物转化为显性2 H-MRI， 可观察到的下游代谢物或（2）2 H底物转化为死端代谢物， 作为2 H-MRI可检测的物质积累。这两个概念通过丰富的 山梨糖醇，D-[6，6 '-2H2]山梨糖醇，其代谢可以通过其转化为乳酸盐/乙醇来检测，或 2-脱氧-D-[2，2 '-2H2]山梨糖醇预期在细菌中作为其6-磷酸化加合物被“捕获”。无论是 例2 H核具有在体2 H MRI成像所需的化学位移。此外，技术 我们的长期目标是将无毒的2 H糖醇应用于 包括儿童在内的弱势群体，而不需要电离辐射。我们先用核磁共振- 用于研究体外细菌中2 H底物代谢的相容性生物反应器（具体目标1）。 然后，我们将展示使用富集底物的细菌特异性2 H掺入，所述富集底物为 代谢为主要的2 H-MRI可检测产物，或被病原体保留为死端分子 （具体目标2）。在特定目标3中，我们将证明使用这些工具在14 T下进行2 H MRI可以检测活体 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.