Biology subjects

Ford, V. J.

Publications and source records attributed to Ford, V. J..

4 recordsLinked to original sources

bioRxiv2026

Real-time, automated, standardized, and transparent analysis of microfluidic nanoparticle data with RPSPASS

Extracellular vesicles (EVs) are lipid spheres released from cells. Research utilizing EVs has met several hurdles owing to the small size of the majority of EVs and other nanoparticles (<150 nm) and the lack of detection technologies capable of providing high-throughput single particle measurements at this scale. The use of high-throughput single particle measurements is critical for the assessment of EV heterogeneity and abundance which are features often used to assess the development of isolation protocols or particle characterization. The Coulter principle, known in the field as resistive pulse sensing (RPS), has been used for several decades to size and count cells. More recently, this technology has evolved to accommodate nanoparticle analysis. In the last decade a platform utilizing microfluidic resistive pulse sensing (MRPS) has been demonstrated for nanoparticles, offering ergonomic characterization of nanoparticles along with utilizing open format data. To date, assessment of MRPS accuracy and reporting standards have not been assessed. With the aim of increasing data accuracy, ergonomics, and reporting transparency, we developed a microfluidic resistive pulse sensing post-acquisition analysis software (RPSPASS) application for automated cohort calibration, population gating, statistical output, QC plot generation, alternative data file outputs, and standardized reporting templates.

bioengineering↗

bioRxiv2025

Myocyte Damage and Mass Loss Drives Increasing Water Content, Compliance, and Survival in Septic Cardiomyopathy

Introduction/PurposeDuring the septic cardiomyopathy, the mechanism and relationship to outcome of changes in left ventricular (LV) end diastolic volume (EDV) and ejection fraction (EF) remains obscure. We compared serial changes in LVEF and LVEDV to successive alterations in LV wall ultrastructure, water content, and total mass to investigate whether these measures can explain their basis. MethodsWe performed cardiac magnetic resonance imaging at 0,6,18,30,42,54, and 92h post-bacterial challenge in a large-animal model (n=57) that mimics human septic cardiomyopathy. LV tissue was obtained for electron microscopy (EM) upon death and 66h in sacrificed survivors. ResultsBetween 0-6h post-challenge, LV compliance and EDV reached its greatest decline. Non-survivors (n=18) exhibited significantly greater reductions in LVEDV, along with more myocyte edema, mitochondrial swelling and myofilament fragmentation on EM. This increased tissue damage may explain why non-survivors developed worse LV compliance and a greater decline in LVEDV, which persisted until death. From 6-30h, LVEDV significantly improved to baseline in non-survivors, while survivors experienced [~]20% increases (n=39). Concurrently, there was significant LV mass loss and increases in percent water content that were significantly associated with increases in LVEDV. This is consistent with a passive mechanism for rapidly improving LV compliance and EDV. Full recovery of EF required additional days. We hypothesize the prolonged significant mass loss over 5d reflects an active process for remodeling fragmented myofilaments, eliminating myocyte edema, and mitochondrial swelling, ultimately restoring contractile function. ConclusionThe septic cardiomyopathy constitutes a diffuse ultrastructural injury to myocytes with three phases. Initially, there is a decrease in LVEDV, and EF due to myocyte damage within 6h of bacterial challenge; next, the patient sees a passive LVEDV recovery from 6-30h, where LV mass loss increases relative wall percent water content, which facilitates wall compliance and LVEDV; and lastly, the patient sees mass loss beyond 30h consistent with an active repair mechanism of myocytes, returning systolic function to normal. Therefore, EDV changes are a pathophysiological biomarker for sepsis outcomes. A lower LVEDV indicates persistent unrepairable ultrastructure damage with worsening wall compliance and poorer outcomes. LVEDV dilation is a sign of near-full recovery of ultrastructure injury, augmenting wall compliance and improving outcomes. Clinical ImplicationsWe explain herein why septic cardiomyopathy findings dont have clinical implications like heart failure. Septic patients who exhibit signs of heart failure, low LVEF with high EDVs, are doing well - reflecting mild myocyte injury, effective damaged tissues clearance, increased relative LV wall water content, and compliance. This augments the LVEDV, lowering the LVEF. Septic patients who deteriorate rapidly, contrary to heart failure patients, show high/normal LVEF and low/normal LVEDV. Here, the myocyte damage is severe, leading to insufficient wall repair, and this decreased wall compliance persists, preventing the LV from dilating and making LVEDV low which ultimately raises the LVEF.

physiology↗

bioRxiv2024

In a Canine Model of Septic Shock, Cardiomyopathy Occurs Independent of Catecholamine Surges and Cardiac Microvascular Ischemia

BackgroundHigh levels of catecholamines are cardiotoxic and associated with stress-induced cardiomyopathies. Septic patients are routinely exposed to endogenously released and exogenously administered catecholamines, which may alter cardiac function and perfusion causing ischemia. Early during human septic shock, left ventricular ejection fraction (LVEF) decreases but normalizes in survivors over 7-10 days. Employing a septic shock model that reproduces these human septic cardiac findings, we investigated the effects of catecholamines on microcirculatory perfusion and cardiac function. MethodsPurpose-bred beagles received intrabronchial Staphylococcus aureus (n=30) or saline (n=6) challenges and septic animals recieved either epinephrine (1mcg/kg/min, n=15) or saline (n=15) infusions from 4 to 44 hours. Serial cardiac magnetic resonance imaging (CMR), invasive hemodynamics and laboratory data including catecholamine levels and troponins were collected over 92 hours. Adenosine-stress perfusion CMR was performed on eight of the fifteen septic epinephrine, and eight of the fifteen septic saline animals. High-dose sedation was titrated for comfort and suppress endogenous catecholamine release. ResultsCatecholamine levels were largely within the normal range throughout the study in animals receiving an intrabronchial bacteria or saline challenge. However, septic versus non-septic animals developed significant worsening of LV; EF, strain, and -aortic coupling that was not explained by differences in afterload, preload, or heart rate. In septic animals that received epinephrine versus saline infusions, plasma epinephrine levels increased 800-fold, pulmonary and systemic pressures significantly increased, and cardiac edema decreased. Despite this, septic animals receiving epinephrine versus saline during and after infusions, had no significant further worsening of LV; EF, strain, or -aortic coupling. Animals receiving saline had a sepsis-induced increase in microcirculatory reserve without troponin elevations. In contrast, septic animals receiving epinephrine had blunted microcirculatory perfusion and elevated troponin levels that persisted for hours after the infusion stopped. During infusion, septic animals that received epinephrine versus saline had significantly greater lactate, creatinine, and alanine aminotransferase levels. ConclusionsCardiac dysfunction during sepsis is not primarily due to elevated endogenous or exogenous catecholamines nor is it principally due to decreased microvascular perfusion-induced ischemia. However, epinephrine itself has potentially harmful long lasting ischemic effects during sepsis including impaired microvascular perfusion that persists after stopping the infusion. Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABSO_LIMyocardial depression of sepsis occurs without high levels of circulating catecholamines. C_LIO_LIWhereas large vessel coronary perfusion is known to be well maintained during sepsis, we show that during the myocardial depression of sepsis, in a model without exogenous catecholamine infusion, no perfusion abnormalities in the coronary microcirculation nor troponin elevations develop, indicating that the cardiac dysfunction of sepsis is not an ischemic injury. C_LIO_LIEpinephrine use during sepsis produces a form of injury tangential to the myocardial depression of sepsis. C_LIO_LIEpinephrine infusions depressed microcirculatory perfusion reserve and increased troponin I levels indicating a secondary prolonged mild ischemic effect on the myocardium. C_LI What are the clinical implications?O_LIProlonged high doses of epinephrine can secondarily contribute to perfusion abnormalities. C_LIO_LIDecoupling the septic heart from microvascular perfusion abnormalities and ischemia may lead to better strategies for managing shock associated with severe infections. In clinical practice in septic patients particularly potentially with coronary artery disease, commonly used vasopressors that are less associated with increased lactate production than epinephrine, alongside adjunct cardiac microcirculatory vasodilators, could help better maintain or improve cardiac performance during septic shock. C_LI

physiology↗

bioRxiv2024

Cardiac Magnetic Resonance Studies in a Large Animal Model that Simulates the Cardiac Abnormalities of Human Septic Shock

BackgroundSeptic shock, in humans and in our well-established animal model, is associated with increases in biventricular end diastolic volume (EDV) and decreases in ejection fraction (EF). These abnormalities occur over 2 days and reverse within 10 days. Septic non-survivors do not develop an increase in EDV. The mechanism for this cardiac dysfunction and EDV differences is unknown. MethodsPurpose-bred beagles randomized to receive intrabronchial Staphylococcus aureus (n=27) or saline (n=6) were provided standard ICU care including sedation, mechanical ventilation, and fluid resuscitation to a pulmonary arterial occlusion pressure of over 10mmHg. No catecholamines were administered. Over 96h, cardiac magnetic resonance imaging, echocardiograms, and invasive hemodynamics were serially performed, and laboratory data was collected. Tissue was obtained at 66h from six septic animals. ResultsFrom 0-96h after bacterial challenge, septic animals vs. controls had significantly increased left ventricular wall edema (6%) and wall thinning with loss of mass (15%) which was more pronounced at 48h in non-survivors than survivors. On histology, edema was located predominantly in myocytes, the interstitium, and endothelial cells. Edema was associated with significantly worse biventricular function (lower EFs), ventricular-arterial coupling, and circumferential strain. In septic animals, from 0-24h, the EDV decreased from baseline and, despite cardiac filling pressures being similar, decreased significantly more in non-survivors. From 24-48h, all septic animals had increases in biventricular chamber sizes. Survivors biventricular EDVs were significantly greater than baseline and in non-survivors, where biventricular EDVs were not different from baseline. Preload, afterload, or HR differences did not explain these differential serial changes in chamber size. ConclusionSystolic and diastolic cardiac dysfunction during sepsis is associated with ventricular wall edema. Rather than differences in preload, afterload, or heart rate, structural alterations to the ventricular wall best account for the volume changes associated with outcome during sepsis. In non-survivors, from 0-24h, sepsis induces a more severe diastolic dysfunction, further decreasing chamber size. The loss of left ventricular mass with wall thinning in septic survivors may, in part explain, the EDV increases from 24-48h. However, these changes continued and even accelerated into the recovery phase consistent with a reparative process rather than ongoing injury. Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABSO_LIUtilizing multimodal imaging and hemodynamics, we demonstrate the cardiac changes of sepsis have injury and reparative phases. C_LIO_LIThe injury phase (0-24h) has EDV decreases more profound in non-survivors and is associated with worse ventricular compliance, myocardial edema, and diastolic dysfunction. C_LIO_LIThe recovery phase has left ventricular mass loss with wall thinning in survivors that explains the EDV increases (24-96h). These progressed into the EF recovery phase consistent with a reparative process removing damaged tissue. C_LIO_LIThis is the first controlled CMR sepsis study supporting ventricular wall edema is a fundamental aspect of sepsis pathophysiology and dry mass loss a reparative mechanism. C_LI What are the clinical implications?O_LIDespite optimizing filling pressures, the cardiac changes in ventricular wall structure and function associated with survival and non-survival in sepsis still occurred, thereby discounting fluid resuscitation as the major factor of therapeutic importance for cardiac function and survival. C_LIO_LIThe changes reported here have potential implications for sepsis treatment especially in the field of fluid resuscitation. These findings yield new understanding into the pathophysiology of sepsis cardiac dysfunction and allow for novel phenotyping and prognosticating of the syndrome with ventricular compliance and EDVs. This also offers potentially high yielding targets for research for new therapeutic approaches for sepsis and heart failure. C_LI

physiology↗