Biology subjects

Dunbar, M.

Publications and source records attributed to Dunbar, M..

4 recordsLinked to original sources

bioRxiv2025

A Window into the Brain's Microcirculation: Retinal Optical Coherence Tomography Angiography (OCTA) as Perioperative Bedside Resuscitation Guide?

ObjectiveQuantifying physiological flow dynamics in the brains microvasculature is vital for effective resuscitation management. Traditional resuscitation approaches rely on macrocirculatory flow targets, which often poorly correlate with cerebral microcirculatory flow. Our observational pilot study investigates the feasibility of using optical coherence tomography angiography (OCTA) to image retinal microcirculatory blood flow in the immediate perioperative setting. MethodsUsing a porcine animal model, we were able to induce hypercarbia, epinephrine-led resuscitation, and hemorrhage followed by autologous re-transfusion scenarios. ResultsVascular density of superficial capillary plexus showed an average increase in perfusion of approximately 4% and 1.2% from baseline for resuscitation and hypercarbia stages, respectively. Conversely, re-transfusion stage showed an approximate average reduction in superficial layer vascular density by 3.9% from baseline. Vascular density of the deep capillary plexus layer showed a significant increase (6.31%) from baseline in for hypercarbia stage but remained unchanged for the rest of the stages. ConclusionsTaken together, OCTA can be (i) utilized in a perioperative setting, (ii) used to detect fast changes in systemic blood pressure, and (iii) utilized for non-invasive cerebral blood flow pattern determination during pre- and post-surgical evaluation of patients. DisclosuresNone

physiology↗

bioRxiv2024

Testing for heavy metals in drinking water collected from Dog Aging Project participants

Heavy metals are commonly found in groundwater and can affect the quality of drinking water. In this pilot study, we analyzed the quality of drinking water for dogs participating in the Dog Aging Project (DAP) who lived in homes not served by a municipal water supply. In order to capture both diverse and localized environmental factors that may affect drinking water, 200 owners of DAP dogs located in one of 10 selected states were invited to participate. We tested for the presence of 28 metals in dogs drinking water, including eight (8) heavy metals that have maximum contaminant levels (MCLs) designated by the Environmental Protection Agency (EPA) and five (5) heavy metals that have EPA health guidance levels. The eight metals with MCLs are known to cause chronic health issues in humans after long-term ingestion. Our aim in this pilot was to determine whether such elements could be detected by at-home sampling of dogs drinking water. We found detectable levels of all metals tested. There were 126 instances when an analyte (arsenic, lead, copper, sodium, strontium, nickel, or vanadium) was above the EPA MCL or health guidance level. We further identified potential association between the presence of titanium and chromium, and occurrence of a known health condition in dogs. This prompts further investigation with a larger, stratified sample analyzing dogs drinking water composition and long-term health and wellness outcomes in dogs living in diverse geographies. These results may impact veterinary care decisions and husbandry, and underscore the validity and importance of utilizing dogs as sentinels of human health outcomes in the context of drinking water contamination.

ecology↗

bioRxiv2023

Maintenance of pig brain function under extracorporeal pulsatile circulatory control (EPCC)

Selective vascular access to the brain is desirable in metabolic tracer, pharmacological and other studies aimed to characterize neural properties in isolation from somatic influences from chest, abdomen or limbs. However, current methods for artificial control of cerebral circulation can abolish pulsatility-dependent vascular signaling or neural network phenomena such as the electrocorticogram even when preserving individual neuronal activity. Thus, we set out to mechanically render cerebral hemodynamics fully regulable to replicate or modify native pig brain perfusion. To this end, blood flow to the head was surgically separated from the systemic circulation and full extracorporeal pulsatile circulatory control (EPCC) delivered via a modified aorta or brachiocephalic artery. This control relied on a computerized algorithm that maintained, for several hours, blood pressure, flow and pulsatility at near-native values individually measured before EPCC. Continuous electrocorticography and brain depth electrode recordings were used to evaluate brain activity relative to the standard offered by awake human electrocorticography. Under EPCC, this activity remained unaltered or minimally perturbed compared to the native circulation state, as did cerebral oxygenation, pressure, temperature and microscopic structure. Thus, our approach enables the study of neural activity and its circulatory manipulation in independence of most of the rest of the organism.

neuroscience↗

bioRxiv2022

Social determinants of health and disease in companion dogs: A cohort study from the Dog Aging Project

Exposure to social environmental adversity is associated with health and survival in many social species, including humans. However, little is known about if and how these health and mortality effects vary across the lifespan, largely due to the difficulty of studying long-lived organisms across much of their lifespan. Here, we leveraged a relatively new and powerful model for human aging, the companion dog, to investigate which components of the social environment are associated with dog health and how these associations vary across the lifespan. We drew on comprehensive survey data collected on 21,410 dogs from the Dog Aging Project and identified five factors that together explained 33.7% of the variation in a dogs social environment. Factors capturing financial and household adversity were associated with poorer health and lower physical mobility in companion dogs, while factors that captured social support, such as living with other dogs, were associated with better health when controlling for dog age and weight. Some of these associations differed across a dogs lifespan, including a stronger relationship between owner age and health in younger (as compared to older) dogs. Taken together, these findings suggest the importance of income, stability, and owner age on owner-reported health outcomes in companion dogs and point to potential behavioral and/or environmental modifiers that can be used to promote healthy aging across species.

evolutionary biology↗