NMR Surgical Laboratory

About the Lab

Nuclear Magnetic Resonance (NMR) technology provides a non-invasive window to the anatomical, biochemical and physiological characteristics of the living organism. For the last thirty years, principal investigator A. Aria Tzika, PhD, has maintained research focus on the investigation of biologically important biomarkers using advanced imaging methodology, including multi-parametric, functional, and physiological and molecular MR imaging (MRI) and MR spectroscopy (MRS). This research aims to elucidate mechanisms underlying injury, neoplasia, and inflammation.

In more general terms, the P.I. is aiming to:

• Move research from in vitro and ex vivo biology to in vivo physiology and integrative biology
• Integrate research in experimental animal models with clinical research and medicine
• Develop therapies for neoplasia, injury, and inflammation

Specifically, Dr. Tzika's research activities are primarily occurring in imaging, but her research approach is strongly influenced by the fact that she was trained as a physiologist. In fact, she believes that the underlying cause of neoplasia, injury, and inflammation in addition to stroke, myocardial infarction as well as aging is dysfunction at the mitochondrial level. The P.I. has thus expanded her basic research program on the "Role of Mitochondria in Injury and Cancer Using Magnetic Resonance." This has been a topic of her interest since graduate school. She believes that the results from this research choosing a paradigm of burn injury are very promising and her publications on the subject testifies for this but, more importantly, they open the horizons of a more general role of mitochondria damage in a variety of traumatic situations and tissue injury in general. Meanwhile, she continues her research in cancer. One of her research projects focuses on developing and optimizing a novel computational approach that combines MRS and molecular genomics data to identify diagnostic biomarker profiles for tissue fingerprinting in clinical medicine. Currently, she is focused on applying these technologies to pediatric brain tumors, the leading cause of pediatric cancer mortality, since she has studied such tumors for over 15 years.

In addition, Dr. Tzika is working on the investigation of novel MR-derived biomarkers for stroke and traumatic brain injury patient rehabilitation using novel MR-compatible rehabilitation devices. Her working hypothesis is that rehabilitation results in functional and/or structural neuroplasticity and improved performance and that I can monitor this plasticity using on-line state-of-the art brain MRI mapping. Such rehabilitation can be also assisted by novel mitochondrial drugs that the P.I. is currently investigating in animal models of trauma.

Finally, as a co-investigator in other colleagues' projects, she is using molecular imaging to investigate inflammatory response, infection and bacterial virulence. She applies NMR spectroscopy, high-resolution magic angle spinning NMR, multi-dimensional NMR, MR imaging, and functional MR imaging to answer specific questions. These techniques are complemented with a large group of collaborators (basic scientists and physicians), who provide support on data mining, molecular biology analysis, engineering design, genetic analysis, clinical evaluation, mathematical modeling and optical imaging.

Research Projects

On the Role of Mitochondria in Injury

This project performs in vitro, ex vivo and in vivo Magnetic Resonance (MR) experiments in tissues and animal injury models to determine metabolic and tissue specific changes. We examine specific biochemical and physiological patterns of expression of injury, which ultimately may correlate to gene expression patterns and the systemic release of regulatory proteins. Furthermore, we investigate antioxidant therapies in animal models that mimic mitochondrial dysfunction caused by injury. The following investigations are in progress:

• Investigation of metabolic tissue response to injury using tissue extracts and/or intact tissues. We will employ state-of-the-art 13C MR spectroscopic methods to study tricarboxylic acid (TCA) cycle fluxes and gluconeogenesis using tissue extracts and/or intact tissues. We will also identify apoptotic changes in tissues associated with burn injury (i.e., liver, muscle)
• Assessment of the mitochondrial energy coupling in vivo using murine models of injury on wild-type and transgenic mice. We measure the ratio of the rate of ATP synthesis and TCA cycle fluxes (rate of mitochondrial substrate oxidation) by 31P and 13C NMR spectroscopy, respectively, to assess mitochondrial energy coupling. We use previously developed experimental injury murine models on wild-type mice and mice deficient in one of the three uncoupler proteins (UCP3 knockout mice) that regulate mitochondrial inner-membrane permeability to protons
• Investigation in murine and nematode models of antioxidant therapies using transgenic murine and Caenorhabditis elegans (C. elegans) models of injury. The importance of mitochondrial reactive oxygen species (ROS) in injury is being investigated in wild-type mice with injury, UCP3 knockout mice and Caenorhabditis elegans (C. elegans) worms treated with catalytic antioxidant drugs using NMR. We use previously developed experimental thermal injury murine models and work on developing new C. elegant worm models of injury

NMR Core for Burn Trauma Center

The overall focus of the Burn Trauma Center is the control of the inflammatory response and its metabolic consequences on the whole patient and the important end organs including the liver, gut, and skeletal muscle. Dr. Tzika’s role is to direct the activities of the NMR core. The NMR Surgical Laboratory provides the Burn Trauma Center with the capability to apply NMR techniques to study phenomena at the tissue, cellular and genetic levels. More specifically the laboratory supports research to develop methodologies that will permit the investigators of the Burn Trauma Center to assess key metabolites in the TCA cycle in tissue extracts and using magic angle spinning, in the whole intact tissue. In addition, investigators will be able to assess mitochondrial energy coupling in vivo, as expressed by the ratio of ATP synthesis to TCA cycle using 13C/31P NMR. NMR Surgical Laboratory offers several services to the Burn Trauma Center:

• Noninvasive assessment of gluconeogenesis and TCA cycle in humans
• NMR of tissue extracts using existing and new techniques
• Developments of new technologies using high resolution magic angle spinning to perform NMR measurements in small, intact, unprocessed tissues
• In vivo NMR spectroscopy and MR imaging microscopy of murine models of burn injury
• Function of MvfR in Pseudomonas aeruginosa Virulence

The goal of this project is to determine the mechanism through which MvfR modulates the expression of quorum sensing (QS)-controlled genes, and how this regulation relates to the QS cascade and bacterial virulence.

Diagnostic Cancer Biomarkers Research Group

The objective of this group is to test the hypothesis that state-of-the-art, high-resolution ex vivo Magnetic Resonance Spectroscopy (MRS) at higher magnetic field strengths can provide biochemical indices, which are feasible biomarkers of proliferative activity and apoptosis in cancer. The hypothesis and the aims of current research build upon previous findings obtained during the course of a previous American Cancer Society-funded project. Current aims include the investigation of cancer biochemistry and its relationship to pathology or gene expression, using ex vivo MRS of intact tumor biopsies, to rigorously define the diagnostic and predictive role of in vivo MRS at high magnetic fields. Our current aims anticipate added significance to our previous findings by offering further insights in cancer biology. This new knowledge will not only advance the utility of ex vivo MRS as an adjunct to neuropathology in operable cancers at present, but will also justify MRS as a clinical diagnostic tool in inoperable tumors in vivo, at higher field strengths. Moreover, exploration of our current aims will provide valuable information regarding a multi-parametric approach, which combines MRS, pathology and molecular biology as a unified characterization of cancers and their response to therapy.

Functional MRI Studies of Neural Function

The rationale for this research is to augment traditional behavioral methods with multi-parametric MR neuroimaging methods that can provide highly relevant information regarding neuronal function by providing a simultaneous rehabilitation therapy and fMRI evaluation while monitoring effectiveness of rehabilitation maneuvers in patients with neurological disorders. The significance of this project is that our findings may lead to the development of an optimal method tailored for rehabilitation of patients with neurological disorders such as stroke, which could evolve into a valuable tool for investigating the pathological or traumatic changes related to the disease while yielding unique prospective information for the management of patients with neurologic disability.

Feasibility of Rehabilitation Robots and fMRI in Stroke

This project will test the hypothesis that optimally designed Magnetic Resonance (MR) compatible robotic devices assist in movement rehabilitation by stimulating plasticity of primary motor cortex representations and cell properties following pathological or traumatic changes due to stroke, we will:

• Explore optimal experimental design for brain functional MR imaging (fMRI) studies of healthy volunteers using novel MR compatible rehabilitation force-feedback robotic devices
• Assess whether our devices and fMRI protocol are suitable for neuroimaging of patients after stroke

Brain Mapping of Attention Network and its Interaction with Working Memory after Traumatic Brain Injury (TBI) Using Novel Magnetic Resonance Imaging Methods

Attention and working memory disturbances are two of the most disabling consequences of TBI and the interaction between the two has seldom been addressed. Our objective is to improve understanding of this interaction in TBI among those with complicated mild or moderate TBI. Our hypothesis is that impaired brain function following TBI causes abnormal interaction between attention and working memory.

Mitochondrial Dysfunction as a Therapeutic Target in Traumatic Brain Injury

The broad, long-term objective of this study is to develop effective treatments to improve the survival and quality of life of individuals with traumatic brain injury (TBI). TBI is a devastating neurological injury and a major cause of life-long impairment and disability in over 1 million people, including a large number of young adults and military personnel. Current clinical assessments and imaging cannot always reliably determine the presence and severity of injury. More importantly, the cellular mechanisms underlying TBI remain unknown. This gap in the understanding of these mechanisms contributes to the lack of clinically effective therapeutics for TBI patients.

Given the considerable information regarding the mechanisms of TBI that has come to light in the last decade and the absence of any cure among the presently available treatments for attenuating TBI, it is timely to examine a hypothesis of mitochondrial dysfunction in TBI, such as that advanced in the present proposal, and to test the influence on TBI of novel agents targeted at mitochondria. The present research aims to make headway by employing state-of-the art in vivo approaches, namely nuclear magnetic resonance (NMR) spectroscopy and electron paramagnetic resonance (EPR), in parallel with molecular, biochemical studies, histopathological and behavioral studies. A clinically relevant murine model consisting of controlled cortical impact (CCI) in which parameters can be set to control injury severity will be used to study wild-type (WT) mice before and TBI with and without injection of a mitochondrial-targeted peptide. Our work will fill a knowledge gap in the molecular mechanisms of TBI, which possibly shares similarities with other types of trauma we have investigated. This is a field of great public health relevance and we are poised to contribute as a qualified multidisciplinary team in an outstanding environment with access to exceptional research facilities.

The hypothesis of the study is that a major cause of TBI is mitochondrial dysfunction involving defects in oxidative phosphorylation (OXPHOS) associated with stimulation of mitochondrial production of reactive oxygen species (ROS) and the resultant damage to mitochondrial DNA (mtDNA). Therefore, it will be essential to measure specific bioenergetic and redox status changes and the production of ROS in mice after TBI and to investigate the efficacy of mitochondrial agents.