David William McMillan, Ph.D.

Biography

I am a dual-role academician at the University of Miami Leonard M. Miller School of Medicine, serving as Research Assistant Professor, Department of Neurological Surgery, and Director of Education and Outreach for our neuroscience center of excellence The Miami Project to Cure Paralysis.


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At The Miami Project (TMP), we conduct research with and for people living with paralysis from spinal cord injury (SCI) and other neurological conditions. Our science spans FDA indication-seeking clinical trials across virtually all clinical research settings—surgical, inpatient, outpatient, and beyond; and we engage various stakeholders across many professional sets—government, nonprofit, for profit, and beyond.

My dissertation pertained to the role of the autonomic nervous system in the absorption, trafficking, and fates of dietary fat. I still keep a keen eye on the neurogenic physiology of feeding and obesity, and also collaborate to develop quantitative autonomic diagnostics. I also align some of my field efforts with regional demands and and affordances—aiming at the disproportionate risks (e.g., hurricanes and heat) and rewards (e.g., scuba and sailing) the Tropical Atlantic poses for people living with disability from paralysis.

I am a daily car-free commuter, a keen purveyor of many forms of adaptive outdoor recreation (culminating in my role as an adapted scuba dive buddy), and earnest contributor to many non-profit efforts and organizations.



Affiliation


Education

Ph.D. in Exercise Physiology, 2020
University of Miami

1° Mentor(s): Dr. Kevin A. Jacobs & Dr. Mark S. Nash
2° Mentor(s): Dr. James L.J. Bilzon

Main Project: My three-part doctoral dissertation began with inquiries into the effect of exercise on postabsorptive and then postprandial macronutrient handling/utilization, and concluded with a project examining the effect of neurological damage on the absorption and transport of dietary lipids.

M.S. in Exercise Science, 2015
California State University, Los Angeles

1° Mentor(s): Dr. Christine J. Dy
2° Mentor(s): Dr. Ray De Leon

Main Project: My master’s thesis was on the topic of “interappendicular neurological coupling”, determining the role of arm-swinging during locomotor rehabilitation on patterns of muscle activity from paralyzed legs during assisted walking.

B.S. in Exercise Science, 2013
California State University, San Marcos

1° Mentor(s): Dr. Todd A. Astorino
2° Mentor(s): Dr. Jeff A. Nessler

Main Project: My bachelor’s thesis pertained to the effect of rest interval on excess post-exercise oxygen consumption after resistance exercise, and then I instigated a study determining the effect of self-pacing on peak physiological response to cycling exercise.


Scientific Interests & Project

Metabolism

Neurological control of the transport, utilization, and storage of macronutrients

To meet the energetic needs of life, metabolic fuels—or macronutrients—are introduced to our system through a single entry point whereby they must be transported widely to their cellular end fate of utilization or storage. The coordination of this complex system—a milieu of nested and ever-specializing organs👉tissues👉cell types—is achieved via a distributed control system. In vertebrates, it follows that the brain is a player in this control system. But the role of the brain in certain metabolic process is no self-evidence… not least from a phenomenological perspective (you cannot, in fact, cause your blood sugar levels to decrease by consciously willing your blood sugar to drop).

  • Transport of new (e.g., dietary) and existing (e.g., stored) fuels occurs via complex trafficking of molecular cargo via blood and lymph vessels between different organ systems.
  • Use, or expenditure, of energy occurs due to different processes (e.g., aerobic vs anaerobic) and acting on different kinds of energetic molecules (e.g., carbohydrates or fats). The aerobic combustion of hydrocarbons—such as “carbs” and fats—requires oxygen. Energy can also be expended at a higher rate, although less sustainably, by anaerobic processes that do not directly require oxygen.
  • Storage of carbohydrates is limited in humans but importantly occurs in the liver and muscles. Fat storage has a higher capacity and occurs mainly in the liver, muscles, and adipocytes (fat cells).

How does our brain, consciously or subconsciously, contribute to these processes?

Empirical Works Involving Data

Theoretical Works Involving Ideas

  • “The Physiology of Neurogenic Obesity: Lessons from Spinal Cord Injury Research” under review in Obesity Facts

Diagnosis and management of cardiometabolic disease and neurogenic obesity in people with spinal cord injury

My dissertation co-mentor, Dr. Mark S. Nash, was the committee chair for the inaugural efforts to construct the Consortium for Spinal Cord Medicine (CSCM) clinical practice guidelines (CPG) for cardiometabolic disease (CMD) in people with spinal cord injury and disorder (SCI). Furthermore, my postdoctoral fellowship was conducted with Dr. David R. Gater, a physician-scientist expert on the management and study of metabolic complications of SCI such as (but not limited to) obesity.

Empirical Works Involving Data

  • Spinal Cord Injury Exercise and Nutrition Conceptual Engagement (SCIENCE) (Registered Clinical Trial NCT03495986)

Theoretical Works Involving Ideas

Physiology

Understanding and diagnosing autonomic function after spinal cord injury

Surely we all appreciate our brains, but phenomenology alone does not lend itself to an appreciation of everything this amazing organ is doing. Along with the self-evident volitional—or somatic—processes that allow us to move and feel, our brains are conducting a silent orchestra to coordinate the many other bodily functions that don’t feel to be under our control. Some of these functions occur via the autonomous action of organs: for example the pancreas has its own internal mechanisms for detecting sugar in the blood that it samples from the hepatic vein. But many of these bodily processes are, to some degree, augmented via signals from the autonomic nervous system that may or may not travel through the spinal cord. Autonomic neurological signals that do travel through the cord, such as the sudomotor cholinergic sympathetic efferents controlling dilation of blood vessels in skin capillary beds, are disrupted by spinal cord injury.

Maybe a clever measure of something external, like the surface of the skin, could allow us to understand the changes to the autonomic nervous system that are complex and otherwise subconscious.

Empirical Works Involving Data

  • Using galvanic skin conductance to determine the sympathetic level of injury in persons with SCI (Conference Presentation)
  • Ishial skin blood flow during and after a bout of functional electrical stimulation (FES) cycling in persons with SCI (Conference Presentation)

Theoretical Works Involving Ideas

  • Pending

Understanding and augmenting somatic sensorimotor function in people with spinal cord injury

Spinal cord injury (SCI) disrupts the transmission of signals between the brain and the final target tissues, such as skeletal muscle cells in the case of volitional motor control. Certain approaches to restoring function aim to either protect or restore the neuronal connections between the brain and the body via the spine. Maybe signals coming from the brain can inspire the nerve to regrow and/or make new connections. Well for restoration these descending signals are likely necessary, but certainly not sufficient (least people could will their way out of paralysis).

We must also remember that the spinal cord is not merely a conduit. The primary computational unit of the nervous system is the synapse, a junction between (not within) neurons. Since direct connection between the brain and muscles is rare, synapses in the spine allow for computation. As the now-old adage goes: the spinal cord is smart. Thus strategies for augmenting spinal output, with or without varying levels of input from the brain, are merited.

Empirical Works Involving Data

Theoretical Works Involving Ideas

Skeletal pathology within spinal cord injury

Both the rate and total magnitude of bone loss following spinal cord injury (SCI) exceeds that of unabated space flight. Clinically, this speaks to the importance of skeletal pathology in this population. SCI greatly increases risk of fracture in a manner that is unique to this population. Interestingly, lumbar spine bone density is largely preserved, and the most common fracture site—which is similar across all levels of injury—is the “knee region” (distal femur/proximal tibia). But physiologically, that bone loss in SCI exceeds what is observed in mechanical unloading alone is a hint. Bone are not just scaffolding.

Empirical Works Involving Data

Theoretical Works Involving Ideas

Climate Health

Spinal cord injury and subtropical coastal climate hazards

Florida’s sociogeographic, economic, and medical affordances have enticed a migration of persons with spinal cord injury (SCI) to this region. Specifically, Southeastern Florida is flat, snowless, has no State income taxes, and contains specialized medical centers. These conditions are advantageous given the mobility, medical, and monetary needs of individuals living with SCI, resulting in a robust community of those who have the means to relocate. Ironically, here in Southeastern Florida the conditions beneficial to living with SCI exist in one of North American’s prominent loci for coastal climate disasters. Yes, modern affordances in this region permit a long and well lived life with SCI; but external stressors resulting in deviations from standards of care quickly result in superimposed and intersecting risks to health and survival. Climatic hazards can impose deviations—such as disruptions of supply chains, alternations in access to energy and materials, and shifts in the type and availability of human resources required for care. In sub-tropical and tropical coastal areas, hurricanes have a disproportionate and often devastating effect on persons living with disabilities such as SCI.

Empirical Works Involving Data

  • Survey study to understand hurricane preparedness in people with SCI, under review in Climate and Development
  • Interview study to understand hurricane preparedness in people with SCI, data collection ongoing via U-LINK grant

Theoretical Works Involving Ideas

  • Pending

Serotonergic Risks and Rewards

Balancing population-specific hazards with potential benefits of psychedelic substances in people with spinal cord injury

A small and quiet but attentive group of academic medical professionals have gained an interest in the population-specific effects of serotonergic psychedelic substances in people living with SCI. There is existing evidence in basic and pre-clinical models for modulation and even regeneration of spinal neurons. Before any exploration of potential benefits in people, however, we start with a thorough vetting of risk. A pathophysiological consideration integrated with anecdote from those who have self-administered quickly revealed a suite of SCI-specific hazards, and much more work needs to be done in this area to understand probability of negative outcomes (i.e, risk) and predictors of such adverse responses. Click here for a lay summary of what we know so far.

Empirical Works Involving Data

Theoretical Works Involving Ideas

  • On the Potential Therapeutic Application of Psychedelic Substances in Spinal Cord Injury (flagship review in preparation)

Grants

Ongoing Extramural Funding

South Florida Spinal Cord Injury Model System
Funder: National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR) Spinal Cord Injury Model Systems Program
Role: Co-Investigator

Mechanisms and Utility of Multisensory Body-Representation in SCI and SCI-Related Neuropathic Pain
Funder: United States Army Medical Research Acquisition Activity (USAMRAA)
Role: Co-Investigator

Ongoing Intramural Funding

None currently

Concluded Funding

Using community-engaged research to launch climate change resilience from an inclusive design beachhead starting with Southeastern Floridians living with spinal cord injury (SCI)
Funder: U-LINK Resilience Challenge
Role: Principal Investigator

Postprandial fat metabolism following an acute exercise bout in persons with spinal cord injuries
Funder: Craig H. Neilsen Foundation (CNF) Spinal Cord Injury on the Translational Spectrum (SCIRTS)
Role: Co-Investigator

Sally Casanova Scholar
Funder: California Pre-Doctoral Program
Role: Fellow


Written Publications

Peer-Reviewed Scientific Papers
& Textbook Chapters

For a comprehensive list of my peer-reviewed academic publications, please see the following third party bibliometrics services:

ORCID iD · NCBI Bibliography · Google Scholar · Scholarship@Miami · Loop · Scopus · Web of Science · Scholia · Dimensions


By Lines

McMillan DW. CripFag: Robert Andy Coombs Photographs the Intersection of Disability, Queerness, and Sex . In: Miami New Times. April 5, 2022.



Science Media Production & Organizing

American Spinal Injury Association (ASIA) Early Career Webinar Series

Tag: A bench to bedside view of the landscape of spinal cord injury research and medicine, through the eyes of early career professionals.

Description: The American Spinal Injury Association (ASIA)’s Early Career Clinician and/or Researcher (ECRC) Webinar Series is “a bench to bedside view of the landscape of spinal cord injury research and medicine, through the eyes of early career professionals.” This multi-part series features episodes focusing a single topic relevant to SCI research and medicine. In each episode, a dyad of presenters will grant us a “parallax perspective” on their SCI topic of expertise: ideally one perspective being more lab-focused and one being more clinic-focused. Each presentation will be 20 min with a following 10 min Q&A. Beyond sharing the emerging work of young professionals in the SCI space, we will also: (1) identify and archive the rising stars in this space, and (2) create a community for networking together these people based on a common mission. This series was founded and is organized/produced by Anne E. Palermo, Rahul Sachdeva, and me… in part with ASIA’s Early Career Committee.

American Spinal Injury Association (ASIA) SCI Science Perspectives Podcast

Tag: A dialogue from two perspectives on emerging scientific literature spanning the full spectrum of spinal cord injury research, from discovery to clinical application.

Description: The American Spinal Injury Association (ASIA)’s SCI Science Perspectives podcast disseminates the latest-and-greatest scientific work in the field of spinal cord injury (SCI) via a conversation with researchers that approaches their work from two perspectives: the “scholarly” perspective and the “community” perspective. First, ASIA’s Committees identify new and influential scientific papers relevant to the committee’s interests. Then the podcast host(s) interview the author(s) of the papers, approaching their project from each perspective. Then, the conversation from perspective is published as its own episode type. This podcast was founded and is produced by Suzanne L. Groah, Marla A. Petriello, and me… in part with ASIA’s Communication Committee.

The Miami Project Open House

Description: Join us for an in-person immersion of The Miami Project (TMP’s) brick-n-mortar across the Lois Pope LIFE Center and the Christine E. Lynn Rehabilitation Center for the Miami Project to Cure Paralysis at UHealth/Jackson. Not only can you experience first-hand the facilities and equipment that enable our world-class neuroscientific efforts, but also get to know the neuroscientists who animate the process. Click here for a review of the 2024 TMP Open House.


Select Video Stories (produced by me)

Select Audio Stories (produced by me)

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