David W. McMillan

David W. McMillan, Ph.D.

Assistant Professor | Director of Education and Outreach

Biography

I am a full-stack academician at the University of Miami Leonard M. Miller School of Medicine where I serve as Research Assistant Professor, Department of Neurological Surgery, and the Director of Education and Outreach at The Miami Project to Cure Paralysis. I conduct research by, with, and for people who have paralysis due to spinal cord injury (SCI). I consider myself a domain-general researcher specializing in a use-case not an approach.

My dissertation was about the role that the autonomic nervous system plays in the absorption, trafficking, and end-fates of dietary lipids. This might seem unrelated to other topics I study, such as climate health, but it seems to me that my interests share the common thread of being fundamentally about "systems and energy".

Maybe my lack of a single ontological category of study is because epistemically, the decision making process that directs my efforts is not entirely my own. I am committed to cultivating reciprocity throughout SCI research. I practice this participatory research in some of my studies, and help others to do so in theirs. To do so I co-founded and co-chair a "SCI Council" where council members with SCI provide researchers with advise on their studies at any point in the research cycle.

Outside of academia I am a daily bicycle commuter, a keen purveyor of many forms of adaptive outdoor recreation, a scuba diver and adaptive dive buddy, and a Board Member and Co-Chair of the Scientific Advisory Committee for Therapeutic Scuba Institute, Inc.

Affiliation

Education

M.A. in Journalism, ongoing (proj. 2023)
University of Miami


Main Project: My project has yet to be determined, but tentatively will pertain to the development of a "science communication" curriculum for a course, and eventually (🤞) a degree track, to be taught through UM's School of Communication.

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 systema milieu of nested and ever-specializing organs👉tissues👉cell typesis 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?


Experiments

Thoughts

  • Stay tuned 😉

Diagnosis and management of cardiometabolic disease 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.


Experiments

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

Thoughts

Physiology

Understanding and augmenting 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.


Experiments

Thoughts

  • Pending

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.


Experiments

  • 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)

Thoughts

  • Pending

Skeletal pathology within and beyond 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.


Experiments

Thoughts

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.


Experiments

  • Pending

Thoughts

  • Pending

Psychedelics

Neurotherapeutic potential of psychedelic substances in people with spinal cord injury

I am leading an international team, self-titled the Neurotherapeutic Psychedelic Research Group, of academic medical professionals who are interested in this topic. We are considering the potential neuromotor and psychological effects of psychedelic substances in the specific use-case of spinal cord injury (SCI). There is existing evidence in basic and pre-clinical models for modulation and even regeneration of spinal neurons. In people, we are working on generating the first evidence for neuromodulatory effects in this population. Low volume (i.e., "microdose") or local (i.e., intrathecal) delivery could allow for neuromotor benefits without perceptual "side effects." But we are also considering how to optimize "macrodose" approaches targeting psychological effects. Will substances interact with standard SCI pharmacopia? Will sitters need to be prepared for physical responses not seen in other populations? Ought at least one sitter be a person with SCI ("peer-sitting")? In the field of SCI, the topic of psychedelics has yet to be addressed. But the time is now.


Experiments

Thoughts

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

Peer-Reviewed Scientific Papers

Farkas GJ, Burton AM, McMillan DW, Sneij A, Gater DG. Diagnosis and Management of Cardiometabolic Risk and Cardiometabolic Syndrome after Spinal Cord Injury. J Pers Med. 2022;12(7):1088. doi: 10.3390/jpm12071088.

Farkas GJ, Burton AM, McMillan DW, Sneij A, Gater DG. Diagnosis and Management of Cardiometabolic Risk and Cardiometabolic Syndrome after Spinal Cord Injury. J Pers Med. 2022;12(7):1088. doi: 10.3390/jpm12071088.

Farkas GJ, Mitchell JR, Sneij A, Thurston C, Rodriguez D, McMillan DW, Tiozzo E, Berg AS, Nash MS, Bilsker MS, Gater DR. Cardiac structure and function relates to body composition and metabolic profiles in high spinal cord injury. The FASEB Journal. 2022;36(S1). doi: 10.1096/fasebj.2022.36.S1.R3536.

Farkas GJ, Sneij A, McMillan DW, Tiozzo E, Nash MS, Gater DG. Energy Expenditure and Nutrient Intake after Spinal Cord Injury: A Comprehensive Review and Practical Recommendations. Br J Nutr. 2021 (online ahead of print). doi: 10.1017/s0007114521003822

McMillan DW, Correa MA, Astorino TA, Nash MS, Gater DR. Virtual strategies for the broad delivery of high intensity exercise in persons with spinal cord injury. Front Act Daily Living. 2021, e-pub ahead of print, 703816. doi: 10.3389/fspor.2021.703816

Jacobs KA, McMillan DW, Maher JL, Bilzon JLJ, Nash MS. Neither postabsorptive resting nor postprandial fat oxidation are related to peak fat oxidation in men with chronic paraplegia. Front Nutr. 2021, e-pub ahead of print, 703652. doi: 10.3389/fnut.2021.703652

McMillan DW, Kressler J, Jacobs KA, Nash MS. Substrate metabolism during recovery from circuit resistance exercise in persons with spinal cord injury. Eur J Appl Physiol. 2021,121,1631-40. doi: 10.1007/s00421-021-04629-0

McMillan DW, Maher JL, Jacobs KJ, Nash MS, Gater DR. Exercise interventions targeting obesity in persons with spinal cord injury. Top Spinal Cord Inj Rehabil. 2021,27(1),109-20. doi: 10.46292/sci20-00058

McMillan DW, Nash MS, Gater DR, Valderrábano RJ. Neurogenic obesity and skeletal pathology in spinal cord injury. Top Spinal Cord Inj Rehabil. 2021,27(1),57-67. doi: 10.46292/sci20-00035

McMillan DW, Maher JL, Jacobs KA, Mendez AJ, Nash MS, Bilzon JLJ, Effects of exercise mode on postprandial metabolism in humans with chronic paraplegia. Med Sci Sport Exerc. 2021,53(7);1495-504. doi: 10.1249/MSS.0000000000002593

McMillan D, de Leon R, Guertin PA, Dy C. The Utility of Interappendicular Connections in Bipedal Locomotion. Curr Pharm Des. 2017,23(12),1734-1740. doi: 10.2174/1381612822666161216115947

Maher JL, McMillan DW, Nash MS. Exercise and Health-Related Risks of Physical Deconditioning After Spinal Cord Injury. Top Spinal Cord Inj Rehabil. 2017,23(3),175-187. doi: 10.1310/sci2303-175

Astorino TA, Schubert MM, Palumbo E, Stirling D, McMillan DW, Gallant R, Dewoskin R. Perceptual Changes in Response to Two Regimens of Interval Training in Sedentary Women. J Strength Cond Res. 2016,30(4),1067-76. doi: 10.1519/JSC.0000000000001175

Astorino TA, McMillan DW, Edmunds RM, Sanchez E. Increased cardiac output elicits higher V̇O2max in response to self-paced exercise. Appl Physiol Nutr Metab. 2015,40(3),223-9. doi: 10.1139/apnm-2014-0305

Astorino TA, Schubert MM, Palumbo E, Stirling D, McMillan DW. Effect of two doses of interval training on maximal fat oxidation in sedentary women. Med Sci Sports Exerc. 2013,45(10),1878-86. doi: 10.1249/MSS.0b013e3182936261

Astorino TA, Schubert MM, Palumbo E, Stirling D, McMillan DW, Cooper C, Godinez J, Martinez D, Gallant R. Magnitude and time course of changes in maximal oxygen uptake in response to distinct regimens of chronic interval training in sedentary women. Eur J Appl Physiol. 2013,113(9),2361-9. doi: 10.1007/s00421-013-2672-1

Nessler JA, McMillan D, Schoulten M, Shallow T, Stewart B, De Leone C. Side by side treadmill walking with intentionally desynchronized gait. Ann Biomed Eng. 2013,41(8),1680-91. doi: 10.1007/s10439-012-0657-6

Text Book Chapters

Maher JL, McMillan DW, Nash MS. The Cardiometabolic Syndrome in SCI: the Role of Physical Deconditioning and Evidence-based Countermeasures. In: The Physiology of Exercise in Spinal Cord Injury. 1 ed. Taylor J, editor. New York, NY: Springer Nature; 2017. Chapter 10; p.199-216.

Some More Writing

My friend Jazz and I have this thing we call Accessibilizing Our Future (AOF) where we put on the record our thoughts on the topic of sustainability and disability. I write primarily through the lens of energy and materials, focusing on coming necessity for reduced resource consumption and the implications that this simplification will have for people with disability.

Tweets

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.

2022 Miami Spinal Cord Injury Summit

Description: This two and a half day conference will provide clinicians, researchers, and persons with spinal cord injury with the latest updates on research and clinical advances across a variety of topics related to spinal cord injury. Thursday and Friday will offer educational lectures/discussion approved for CME and CEU credits, on topics from advances in cell-based therapies for neural repair to recreational therapy for improved quality of life. A ½ day morning expo will be held on Saturday for those with spinal cord injury to try out adaptive recreational activities, learn about spinal cord injury community resources, and tour the new Christine Lynn Rehabilitation Center for the Miami Project to Cure Paralysis at UHealth/Jackson. CMEs and CEUs will be available to professionals who register and attend this conference.

Anyone who believes in indefinite growth in anything physical, on a physically finite planet, is either mad or an economist.- Kenneth E. Boulding, oft re-quoted by Sir David Attenborough
Lightning and thunder require time, the light of the stars requires time, deeds, though done, still require time to be seen and heard.- Friedrich Nietzsche, The Parable of the Madman
The forms of rebellion that will end up changing anything meaningfully here will be very quiet and very individual and probably not all that interesting to look at from the outside.- David Foster Wallace, 2003 interview with ZDF
The true biologist deals with life, with teeming boisterous life, and learns something from it, learns that the first rule of life is living.- John Steinbeck, The Log from the Sea of Cortez