AMP‐activated protein kinase (AMPK) is a cellular energetic regulator that is known to modify bot... more AMP‐activated protein kinase (AMPK) is a cellular energetic regulator that is known to modify both metabolic and contractile function in the heart. Phosphorylation by an upstream kinase complex (LKB1/MO25/STRAD; LMS) is required for AMPK activation. Yet, the relationship between the LMS, AMPK activation, and myofilament function is unknown. Accordingly, we hypothesized that the upstream kinase complex can regulate myofilament function independently or in combination with AMPK. To do this, demembranated (skinned) rat cardiac trabeculae were incubated with either the LMS or with varying ratios of the LMS with AMPK and myofilament function was measured. Skinned rat trabeculae treated with the LMS alone were desensitized to Ca2+ and had lowered maximum tension. Adding increasing amounts of AMPK in combination with LMS reversed this effect increasing Ca2+‐sensitivity of tension and maximum tension. We furthered hypothesized that the mechanism underlying this relationship is mediated thro...
Advances in sequencing and bioinformatics technologies have allowed unprecedented characterizatio... more Advances in sequencing and bioinformatics technologies have allowed unprecedented characterization of the gut microbiome. As a result, there is a growing appreciation that our microbial environment plays a critical role in the maintenance of health and the pathogenesis of disease. Accordingly, recent evidence suggests a role for gut microbiota in modulating cardiovascular disease and cardiac injury. We hypothesized that administration of the probiotic, Bifidobacterium animalis subsp. lactis 420 (B420), to mice will mitigate the pathological impact of ischemic heart disease (IHD), and that anti-inflammatory T regulatory (T reg ) immune cells are necessary to impart protection against IHD as a result of B420 administration. Pretreatment with B420 for 14 or 35 days attenuated cardiac injury from ischemia/reperfusion or permanent coronary ligation. Infarcted hearts from B420 treated animals displayed a significant reduction in pro-inflammatory markers and an increase in anti-inflammator...
Objectives: MicroRNAs (miRs) have been identified as chief post-transcriptional regulators of car... more Objectives: MicroRNAs (miRs) have been identified as chief post-transcriptional regulators of cardiac disease progression. In addition, a critical role of the adenosine monophosphate-activated kinase (AMPK) pathway in the development of myocardial hypertrophy has been revealed. Yet, regulation of the AMPK pathway by miRs in the heart has not been addressed. We hypothesized that components of the AMPK pathway are targeted by miRs and alter AMPK signaling in a mouse model of hypertrophic cardiomyopathy (HCM). Methods and results: Using real-time PCR, a candidate miR screen that included 22 miRs implicated in pathological cardiac disease and/or metabolic dysregulation was performed on hearts from 60-, 120-, and 240-day-old transgenic HCM male mice harboring an R403Q mutation in the myosin heavy gene. Among early (60 day) elevated miRs were miR-195 and -451. Both miR-195 and -451 have conserved target sites in the 3′ UTR of CAB39 (MO25), a central component of the MO25/STRAD/LKB1 comple...
American Journal of Respiratory and Critical Care Medicine, 2021
INTRODUCTION Cigarette smoke (CS) inhalation triggers oxidative stress and inflammation, leading ... more INTRODUCTION Cigarette smoke (CS) inhalation triggers oxidative stress and inflammation, leading to accelerated lung aging, apoptosis, emphysema, and systemic pathologies. Metformin is beneficial against aging-related diseases, and we hypothesized that it may ameliorate CS-induced pathologies of emphysematous COPD. METHODS Mice were exposed chronically to CS and fed metformin for the second half of exposure. Lung, kidney, and muscle pathologies, lung proteostasis, endoplasmic reticulum (ER) stress, mitochondrial function, and mediators of metformin effects in vivo and/or in vitro were studied. We evaluated the association of metformin use with indices of emphysema progression over five years of follow-up among the COPDGene Study participants. The association of metformin use with percent emphysema and adjusted lung density was estimated with a linear mixed model. RESULTS Metformin protected against CS-induced pulmonary inflammation, airspace enlargement, and small airway remodeling, glomerular shrinkage, oxidative stress, apoptosis, telomere damage, aging, dysmetabolism in vivo and in vitro, and ER stress. The AMPK pathway was central to metformin protective action. Within COPDGene, participants taking metformin compared to those not on it had slower progression of emphysema (-0.92%, CI; -1.7 to -0.14%, p = 0.02) and adjusted lung density decrease (2.2 g/L; 95% CI 0.43 to 4.0 g/L, p = 0.01). CONCLUSIONS Metformin protected against CS-induced lung, renal, and muscle injury, mitochondrial dysfunction, and UPR-ER stress in mice. In humans, metformin use was associated with lesser emphysema progression over time. Our results provide a rationale for clinical trials testing the efficacy of metformin in limiting emphysema progression and its systemic consequences.
The opioid receptors are important regulators of pain, reward, and addiction. Limited evidence su... more The opioid receptors are important regulators of pain, reward, and addiction. Limited evidence suggests the mu and delta opioid receptors form a heterodimer (MDOR), which may act as a negative feedback brake on opioid-induced analgesia. However, evidence for the MDOR in vivo is indirect and limited, and there are few selective tools available. We recently published the first MDOR-selective antagonist, D24M, allowing us to test the role of the MDOR in mice. We thus cotreated CD-1 mice with D24M and opioids in tail flick, paw incision, and chemotherapy-induced peripheral neuropathy pain models. D24M treatment enhanced oxymorphone antinociception in all models by 54.7% to 628%. This enhancement could not be replicated with the mu and delta selective antagonists CTAP, naltrindole, and naloxonazine, and D24M had a mild transient effect in the rotarod test, suggesting this increase is selective to the MDOR. However, D24M had no effect on morphine or buprenorphine, suggesting that only spe...
In critically ill COVID-19 patients, the risk of long-term neurological consequences is just begi... more In critically ill COVID-19 patients, the risk of long-term neurological consequences is just beginning to be appreciated. While recent studies have identified that there is an increase in structural injury to the nervous system in critically ill COVID-19 patients, there is little known about the relationship of COVID-19 neurological damage to the systemic inflammatory diseases also observed in COVID-19 patients. The purpose of this pilot observational study was to examine the relationships between serum neurofilament light protein (NfL, a measure of neuronal injury) and co-morbid cardiovascular disease (CVD) and neurological complications in COVID-19 positive patients admitted to the intensive care unit (ICU). In this observational study of one-hundred patients who were admitted to the ICU in Tucson, Arizona between April and August 2020, 89 were positive for COVID-19 (COVID-pos) and 11 were COVID-negative (COVID-neg). A healthy control group (n=8) was examined for comparison. The p...
Post-operative atrial fibrillation (POAF) continues to be a devastating complication following ca... more Post-operative atrial fibrillation (POAF) continues to be a devastating complication following cardiac surgery, affecting 25-40% coronary artery bypass graft (CABG) (1,2) and 30-40% valve patients (3). Although POAF is thought to be transient in nature, peaking on post-operative days 2-4 and resolving within 4-6 weeks (4), there is mounting evidence to suggest POAF increases risk of stroke, respiratory failure, pneumonia, morbidity and mortality, longer intensive care unit and hospital stays, and increased resource use (4-13). Recent advancements and current research indicate POAF is in part preventable (4); however, progress has been hindered by scarce, conflicting data, and lack of knowledge on independent predictors, effective interventions, and a consistent, all-encompassing clinical and biochemical database. Currently, the use of statistical analysis is common to assess an individual's risk of developing POAF. However, this method limits plasticity and fails to account for ongoing changes in clinical and functional indices during peri-operative stay. Despite continuing growth in POAF literature, POAF incidence has not changed over the past three decades (12). This poses the question-can we predict and detect POAF more effectively? That is, can we stack patient factors and comorbidities with real-time, continuous data from multimodal streams to better predict, diagnose, and manage patients for improving personalized care? Whether utilizing advanced neural networks (NN) such as convolutional NN to diagnose skin lesions or automate the classification of radiological reports for clinical care, machine learning (ML) has demonstrated superiority to traditional statistical methods for predictive scoring and diagnosis. Similarly, within the cardiovascular arena, several
Journal of Pharmacology and Experimental Therapeutics, 2019
Increasing evidence indicates that decreased brain blood flow, increased reactive oxygen species ... more Increasing evidence indicates that decreased brain blood flow, increased reactive oxygen species (ROS) production, and proinflammatory mechanisms accelerate neurodegenerative disease progression such as that seen in vascular contributions to cognitive impairment and dementia (VCID) and Alzheimer's disease and related dementias. There is a critical clinical need for safe and effective therapies for the treatment and prevention of cognitive impairment known to occur in patients with VCID and chronic inflammatory diseases such as heart failure (HF), hypertension, and diabetes. This study used our mouse model of VCID/HF to test our novel glycosylated angiotensin-(1-7) peptide Ang-1-6-O-Ser-Glc-NH2 (PNA5) as a therapy to treat VCID and to investigate circulating inflammatory biomarkers that may be involved. We demonstrate that PNA5 has greater brain penetration compared with the native angiotensin-(1-7) peptide. Moreover, after treatment with 1.0/mg/kg, s.c., for 21 days, PNA5 exhibits up to 10 days of sustained cognitive protective effects in our VCID/HF mice that last beyond the peptide half-life. PNA5 reversed object recognition impairment in VCID/HF mice and rescued spatial memory impairment. PNA5 activation of the Mas receptor results in a dose-dependent inhibition of ROS in human endothelial cells. Last, PNA5 treatment decreased VCID/HF-induced activation of brain microglia/macrophages and inhibited circulating tumor necrosis factor a, interleukin (IL)-7, and granulocyte cell-stimulating factor serum levels while increasing that of the anti-inflammatory cytokine IL-10. These results suggest that PNA5 is an excellent candidate and "first-inclass" therapy for treating VCID and other inflammation-related brain diseases.
According to the CDC (2017), more women than men have died from heart disease over the last 20-25... more According to the CDC (2017), more women than men have died from heart disease over the last 20-25 years. Yet, premenopausal women are protected against heart and cardiovascular disease (CVD) compared to age-matched men. The cellular and molecular mechanisms underlying the transition from premenopause/perimenopause (CVD-resistance) to postmenopause (CVD-susceptible) in women is unknown and is the focus of this project. The critical barrier impeding translational progress is the lack of appropriate models to study menopause. Most studies have used surgical removal of ovaries (ovariectomy) as a model of menopause; yet this technique poorly recapitulates the natural, physiological transition to menopause that 90% of women experience. We overcome this barrier with administration of the chemical, 4-vinylcyclohexene diepoxide (VCD), where we can mirror progressive ovarian failure and preserve the critical “perimenopause” transitional period, identical to humans. Using this model, we demons...
Given the limited treatment options for advanced heart failure, the intrinsic regenerative proper... more Given the limited treatment options for advanced heart failure, the intrinsic regenerative properties of stem cells have been evaluated for myocardial remodeling. Previous stem cells techniques for myocardiocyte remodeling have been limited by the low cellular retention. Presented is a hybrid approach for remodeling infarcted myocardium through implantation of allogeneic human amniotic fluid–derived mesenchymal stem cells within micronized human allograft-derived liquid matrix during the performance of transmyocardial revascularization (TMR). Given the induced increase in vascular density from TMR, we hypothesize that it may serve as a therapeutic delivery system for stem cell placement into damaged myocardium. We present a patient with ischemic cardiomyopathy and refractory angina, who clinically improved after this hybrid therapy of intraoperative TMR and placement of amniotic fluid–derived mesenchymal stem cells and liquid matrix within the TMR channels. Noninvasive testing of my...
Temporary mechanical circulatory support device without sternotomy has been highly advocated for ... more Temporary mechanical circulatory support device without sternotomy has been highly advocated for severe cardiogenic shock patient but little is known when coupled with amniotic stem cell therapy. This case reports the first dual therapy of temporary left ventricular extracorporeal device CentriMag with distal banding technique and human amniotic stem cell injection for treating a severe refractory cardiogenic shock of an 68-year-old female patient. A minimally-invasive off-pump LVAD was established by draining from the left ventricle and returning to the right axillary artery with distal arterial banding to prevent right upper extremity hyperperfusion. Amniotic stem cells were injected intramyocardially at the left ventricular apex, lateral wall, inferior wall, and right subclavian vein. The concomitant use of the temporary minimally-invasive off-pump CentriMag placement and stem cell therapy not only provided an alternative to cardiopulmonary bypass and full-median sternotomy proce...
Lungs donated after cardiac death (DCD) are an underutilized resource for a dwindling donor lung ... more Lungs donated after cardiac death (DCD) are an underutilized resource for a dwindling donor lung transplant pool. Our study investigates the potential of a novel preservation solution, Somah, to better preserve statically stored DCD lungs, for an extended time period, when compared to low-potassium dextran solution (LPD). We hypothesize that Somah is a metabolically superior organ preservation solution for hypothermic statically stored porcine DCD lungs, possibly improving lung transplant outcomes. Porcine DCD lungs (n = 3 per group) were flushed with and submerged in cold preservation solution. The lungs were stored up to 12 h, and samples were taken from lung tissue and the preservation medium throughout. Metabolomic and redox potential were analyzed using high performance liquid chromatography, mass spectrometry, and RedoxSYS®, comparing substrate and pathway utilization in both preservation solutions. Glutathione reduction was seen in Somah but not in LPD during preservation. Ca...
Patients with congestive heart failure (CHF) have increased hospital readmission rates and mortal... more Patients with congestive heart failure (CHF) have increased hospital readmission rates and mortality if they are concomitantly diagnosed with cognitive decline and memory loss. Accordingly, we developed a preclinical model of CHF-induced cognitive impairment with the goal of developing novel protective therapies against CHF related cognitive decline. CHF was induced by ligation of the left coronary artery to instigate a myocardial infarction (MI). By 4- and 8-weeks post-MI, CHF mice had approximately a 50% and 70% decline in ejection fraction as measured by echocardiography. At both 4- and 8-weeks post-MI, spatial memory performance in CHF mice as tested using the Morris water task was significantly impaired as compared with sham. In addition, CHF mice had significantly worse performance on object recognition when compared with shams as measured by discrimination ratios during the novel object recognition NOR task. At 8-weeks post-MI, a subgroup of CHF mice were given Angiotensin (A...
The heart undergoes extensive morphological, metabolic, and energetic remodeling in response to i... more The heart undergoes extensive morphological, metabolic, and energetic remodeling in response to inherited, or familial, hypertrophic cardiomyopathies (FHC). Myocyte contractile perturbations downstream of Ca 2+ , the so-called sarcomere-controlled mechanisms, may represent the earliest indicators of this remodeling. We can now state that the dynamics of cardiac contraction and relaxation during the progression of FHC are governed by downstream mechanisms, particularly the kinetics and energetics of actin and myosin interaction to drive the trajectory of pathological cardiac remodeling. This notion is unambiguously supported by elegant studies above linking inheritable FHCcausing mutations to cardiomyopathies, known to disturb contractile function and alter the energy landscape of the heart. Although studies examining the biophysical properties of cardiac myocytes with FHC-causing mutations have yielded a cellular and molecular understanding of myofilament function, this knowledge has had limited translational success. This is driven by a critical failure in elucidating an integrated and sequential link among the changing energy landscape, myofilament function, and initiated signaling pathways in response to FHC. Similarly, there continues to be a major gap in understanding the cellular and molecular mechanisms contributing to sex differences in FHC development and progression. The primary reason for this gap is a lack of a "unifying" or "central" hypothesis that integrates signaling cascades, energetics, sex and FHC.
American Journal of Physiology-Heart and Circulatory Physiology, 2016
Familial hypertrophic cardiomyopathy (HCM) is a disease of the sarcomere and may lead to hypertro... more Familial hypertrophic cardiomyopathy (HCM) is a disease of the sarcomere and may lead to hypertrophic, dilated, restrictive, and/or arrhythmogenic cardiomyopathy, congestive heart failure, or sudden cardiac death. We hypothesized that hearts from transgenic HCM mice harboring a mutant myosin heavy chain increase the energetic cost of contraction in a sex-specific manner. To do this, we assessed Ca2+sensitivity of tension and crossbridge kinetics in demembranated cardiac trabeculas from male and female wild-type (WT) and HCM hearts at an early time point (2 mo of age). We found a significant effect of sex on Ca2+sensitivity such that male, but not female, HCM mice displayed a decrease in Ca2+sensitivity compared with WT counterparts. The HCM transgene and sex significantly impacted the rate of force redevelopment by a rapid release-restretch protocol and tension cost by the ATPase-tension relationship. In each of these measures, HCM male trabeculas displayed a gain-of-function when c...
Journal of Biomedical Science and Engineering, 2016
Hospital inquired post-operative infections are a leading cause of morbidity and mortality in pat... more Hospital inquired post-operative infections are a leading cause of morbidity and mortality in patients receiving left ventricular assist devices. We present the case of a patient who acquired Candida albicans and Staphylococci infections following left ventricular assist device implantation. Use of standard antibiotics caused the infection to worsen, thus an amniotic membrane patch was used as a last-resort treatment. Within 6 weeks of the amniotic membrane patch treatment, the infection resolved, the wound appeared exceptionally clean upon inspection, and granulation tissue was present. After the infection resolved, a successful latissimusdorsi tissue flap procedure was completed and the patient made a full recovery.
It is well established that heart beat is triggered by electrical excitation, followed by an incr... more It is well established that heart beat is triggered by electrical excitation, followed by an increase in [Ca 2þ ] i and ensuing activation of myofilaments in cardiomyocytes. This property is the basis for the regulation of the heart with electric stimulators or chemical compounds that mediate Ca 2þ signaling. Recently, we found that microscopic heat pulses induce contractions in isolated rat cardiomyocytes without a rise in [Ca 2þ ] i (Oyama, K. et al., Biochem. Biophys. Res. Commun., 417, 607-612, 2012). Microscopic heat pulses produced by focusing infrared laser beam increase temperature of the extracellular solution near cardiomyocytes. In our experiments, a microscopic heat pulse (DT = 5 C for 0.5 sec) induced contractions at a basal temperature of 36 C. When heat pulses were repeatedly applied at 2.5 Hz, oscillatory contractions were observed. In contrast to the electric field stimulation, Ca 2þ transients were not detected during the course of contraction. Moreover, we confirmed that skinned cardiomyocytes are thermally activated in the Ca 2þ-free solution. To elucidate the molecular mechanism of thermal activation, microscopic heat pulses were applied to an in vitro motility assay system utilizing reconstituted thin filaments (rabbit skeletal actin filaments reconstituted with human cardiac tropomyosin and bovine cardiac troponin). Thin filaments started to move during heating in the absence of Ca 2þ , and most of filaments immediately stopped after switching the laser off, demonstrating that thin filaments can be thermally activated, presumably due to the weakening of the binding affinity of the troponin-tropomyosin complex with actin (Ishiwata, S., Biochim. Biophys. Acta, 534, 350-357, 1978). These results suggest that heat pulses can regulate cardiac contractions by shifting the ''on-off'' equilibrium in the thin filament toward the ''on'' state, without accompanying intracellular Ca 2þ transients.
Nebulin is a giant filamentous protein that is coextensive with the actin filaments of the skelet... more Nebulin is a giant filamentous protein that is coextensive with the actin filaments of the skeletal muscle sarcomere. Nebulin mutations are the main cause of nemaline myopathy (NEM), with typical adult patients having low expression of nebulin, yet the roles of nebulin in adult muscle remain poorly understood. To establish nebulin's functional roles in adult muscle we studied a novel conditional nebulin KO (Neb cKO) mouse model in which nebulin deletion was driven by the muscle creatine kinase (MCK)…
Medical Imaging 1995: Physiology and Function from Multidimensional Images, 1995
Electron beam computed tomography (EBCT) is a potentially useful modality to quantitate regional ... more Electron beam computed tomography (EBCT) is a potentially useful modality to quantitate regional pulmonary flow (RPF) with minimal invasiveness, in part because it has good spatial and temporal resolution. The present studies used a single compartment model of indicator transport and EBCT to measure regional tissue flow in the lungs of human subjects. The model postulates that flow is proportional to maximal enhancement and assumes complete tissue accumulation of indicator before significant indicator washout (WO). EBCT flow studies were retrospectively analyzed with respect to RPF in 10 adult patients who had undergone clinically indicated or research cardiovascular studies. Time density curves from the left atrial (LA) cavity and one-third segments of left (LL) and right (RL) lungs (A: anterior, M: middle, and P: posterior segments) were used to calculate RPF. Washout was determined as the percent of the LA curve at the time of peak parenchymal opacification using gamma curve fits to both tissue data and the LA curve data. Mean +/- standard deviation RPF in ml/min/ml was 0.8 +/- 0.4, 1.1 +/- 0.4, and 1.3 +/- 0.4 for A, M, and P respectively for one-third regions in the left lung. Similar results were found in the right lung. No difference in RPF was found when images were measured either by including the largest of visible parenchymal vessels or when such vessels were excluded. Flow in A of LL and RL was less than that in M or P. Average WO was about 10%, with a range of 0-41% of the LA curve area. There was no significant difference between one-third segment WO using pairwise comparison on the left and right sides when tested separately. RPF values were greater in the posterior vs anterior regions of these supine patients. In conclusion, EBCT can detect gravity related flow differences in the human lung. EBCT has potential for clinical assessment of absolute regional pulmonary flow determination in animals and man.
Proceedings of 16th Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Many elastic biologic structures are spherical or nearly so: their mechanics with regard to press... more Many elastic biologic structures are spherical or nearly so: their mechanics with regard to pressure and distending volume are not widely understood. Pressure (P) and volume (V) during inflation and deflation were determined in 9 rubber spheres with wall thickness ratio (WTR) ranging from 0.01 to 1.79. P rose with inflation: with more inflation P peaked and declined. The stress-length
AMP‐activated protein kinase (AMPK) is a cellular energetic regulator that is known to modify bot... more AMP‐activated protein kinase (AMPK) is a cellular energetic regulator that is known to modify both metabolic and contractile function in the heart. Phosphorylation by an upstream kinase complex (LKB1/MO25/STRAD; LMS) is required for AMPK activation. Yet, the relationship between the LMS, AMPK activation, and myofilament function is unknown. Accordingly, we hypothesized that the upstream kinase complex can regulate myofilament function independently or in combination with AMPK. To do this, demembranated (skinned) rat cardiac trabeculae were incubated with either the LMS or with varying ratios of the LMS with AMPK and myofilament function was measured. Skinned rat trabeculae treated with the LMS alone were desensitized to Ca2+ and had lowered maximum tension. Adding increasing amounts of AMPK in combination with LMS reversed this effect increasing Ca2+‐sensitivity of tension and maximum tension. We furthered hypothesized that the mechanism underlying this relationship is mediated thro...
Advances in sequencing and bioinformatics technologies have allowed unprecedented characterizatio... more Advances in sequencing and bioinformatics technologies have allowed unprecedented characterization of the gut microbiome. As a result, there is a growing appreciation that our microbial environment plays a critical role in the maintenance of health and the pathogenesis of disease. Accordingly, recent evidence suggests a role for gut microbiota in modulating cardiovascular disease and cardiac injury. We hypothesized that administration of the probiotic, Bifidobacterium animalis subsp. lactis 420 (B420), to mice will mitigate the pathological impact of ischemic heart disease (IHD), and that anti-inflammatory T regulatory (T reg ) immune cells are necessary to impart protection against IHD as a result of B420 administration. Pretreatment with B420 for 14 or 35 days attenuated cardiac injury from ischemia/reperfusion or permanent coronary ligation. Infarcted hearts from B420 treated animals displayed a significant reduction in pro-inflammatory markers and an increase in anti-inflammator...
Objectives: MicroRNAs (miRs) have been identified as chief post-transcriptional regulators of car... more Objectives: MicroRNAs (miRs) have been identified as chief post-transcriptional regulators of cardiac disease progression. In addition, a critical role of the adenosine monophosphate-activated kinase (AMPK) pathway in the development of myocardial hypertrophy has been revealed. Yet, regulation of the AMPK pathway by miRs in the heart has not been addressed. We hypothesized that components of the AMPK pathway are targeted by miRs and alter AMPK signaling in a mouse model of hypertrophic cardiomyopathy (HCM). Methods and results: Using real-time PCR, a candidate miR screen that included 22 miRs implicated in pathological cardiac disease and/or metabolic dysregulation was performed on hearts from 60-, 120-, and 240-day-old transgenic HCM male mice harboring an R403Q mutation in the myosin heavy gene. Among early (60 day) elevated miRs were miR-195 and -451. Both miR-195 and -451 have conserved target sites in the 3′ UTR of CAB39 (MO25), a central component of the MO25/STRAD/LKB1 comple...
American Journal of Respiratory and Critical Care Medicine, 2021
INTRODUCTION Cigarette smoke (CS) inhalation triggers oxidative stress and inflammation, leading ... more INTRODUCTION Cigarette smoke (CS) inhalation triggers oxidative stress and inflammation, leading to accelerated lung aging, apoptosis, emphysema, and systemic pathologies. Metformin is beneficial against aging-related diseases, and we hypothesized that it may ameliorate CS-induced pathologies of emphysematous COPD. METHODS Mice were exposed chronically to CS and fed metformin for the second half of exposure. Lung, kidney, and muscle pathologies, lung proteostasis, endoplasmic reticulum (ER) stress, mitochondrial function, and mediators of metformin effects in vivo and/or in vitro were studied. We evaluated the association of metformin use with indices of emphysema progression over five years of follow-up among the COPDGene Study participants. The association of metformin use with percent emphysema and adjusted lung density was estimated with a linear mixed model. RESULTS Metformin protected against CS-induced pulmonary inflammation, airspace enlargement, and small airway remodeling, glomerular shrinkage, oxidative stress, apoptosis, telomere damage, aging, dysmetabolism in vivo and in vitro, and ER stress. The AMPK pathway was central to metformin protective action. Within COPDGene, participants taking metformin compared to those not on it had slower progression of emphysema (-0.92%, CI; -1.7 to -0.14%, p = 0.02) and adjusted lung density decrease (2.2 g/L; 95% CI 0.43 to 4.0 g/L, p = 0.01). CONCLUSIONS Metformin protected against CS-induced lung, renal, and muscle injury, mitochondrial dysfunction, and UPR-ER stress in mice. In humans, metformin use was associated with lesser emphysema progression over time. Our results provide a rationale for clinical trials testing the efficacy of metformin in limiting emphysema progression and its systemic consequences.
The opioid receptors are important regulators of pain, reward, and addiction. Limited evidence su... more The opioid receptors are important regulators of pain, reward, and addiction. Limited evidence suggests the mu and delta opioid receptors form a heterodimer (MDOR), which may act as a negative feedback brake on opioid-induced analgesia. However, evidence for the MDOR in vivo is indirect and limited, and there are few selective tools available. We recently published the first MDOR-selective antagonist, D24M, allowing us to test the role of the MDOR in mice. We thus cotreated CD-1 mice with D24M and opioids in tail flick, paw incision, and chemotherapy-induced peripheral neuropathy pain models. D24M treatment enhanced oxymorphone antinociception in all models by 54.7% to 628%. This enhancement could not be replicated with the mu and delta selective antagonists CTAP, naltrindole, and naloxonazine, and D24M had a mild transient effect in the rotarod test, suggesting this increase is selective to the MDOR. However, D24M had no effect on morphine or buprenorphine, suggesting that only spe...
In critically ill COVID-19 patients, the risk of long-term neurological consequences is just begi... more In critically ill COVID-19 patients, the risk of long-term neurological consequences is just beginning to be appreciated. While recent studies have identified that there is an increase in structural injury to the nervous system in critically ill COVID-19 patients, there is little known about the relationship of COVID-19 neurological damage to the systemic inflammatory diseases also observed in COVID-19 patients. The purpose of this pilot observational study was to examine the relationships between serum neurofilament light protein (NfL, a measure of neuronal injury) and co-morbid cardiovascular disease (CVD) and neurological complications in COVID-19 positive patients admitted to the intensive care unit (ICU). In this observational study of one-hundred patients who were admitted to the ICU in Tucson, Arizona between April and August 2020, 89 were positive for COVID-19 (COVID-pos) and 11 were COVID-negative (COVID-neg). A healthy control group (n=8) was examined for comparison. The p...
Post-operative atrial fibrillation (POAF) continues to be a devastating complication following ca... more Post-operative atrial fibrillation (POAF) continues to be a devastating complication following cardiac surgery, affecting 25-40% coronary artery bypass graft (CABG) (1,2) and 30-40% valve patients (3). Although POAF is thought to be transient in nature, peaking on post-operative days 2-4 and resolving within 4-6 weeks (4), there is mounting evidence to suggest POAF increases risk of stroke, respiratory failure, pneumonia, morbidity and mortality, longer intensive care unit and hospital stays, and increased resource use (4-13). Recent advancements and current research indicate POAF is in part preventable (4); however, progress has been hindered by scarce, conflicting data, and lack of knowledge on independent predictors, effective interventions, and a consistent, all-encompassing clinical and biochemical database. Currently, the use of statistical analysis is common to assess an individual's risk of developing POAF. However, this method limits plasticity and fails to account for ongoing changes in clinical and functional indices during peri-operative stay. Despite continuing growth in POAF literature, POAF incidence has not changed over the past three decades (12). This poses the question-can we predict and detect POAF more effectively? That is, can we stack patient factors and comorbidities with real-time, continuous data from multimodal streams to better predict, diagnose, and manage patients for improving personalized care? Whether utilizing advanced neural networks (NN) such as convolutional NN to diagnose skin lesions or automate the classification of radiological reports for clinical care, machine learning (ML) has demonstrated superiority to traditional statistical methods for predictive scoring and diagnosis. Similarly, within the cardiovascular arena, several
Journal of Pharmacology and Experimental Therapeutics, 2019
Increasing evidence indicates that decreased brain blood flow, increased reactive oxygen species ... more Increasing evidence indicates that decreased brain blood flow, increased reactive oxygen species (ROS) production, and proinflammatory mechanisms accelerate neurodegenerative disease progression such as that seen in vascular contributions to cognitive impairment and dementia (VCID) and Alzheimer's disease and related dementias. There is a critical clinical need for safe and effective therapies for the treatment and prevention of cognitive impairment known to occur in patients with VCID and chronic inflammatory diseases such as heart failure (HF), hypertension, and diabetes. This study used our mouse model of VCID/HF to test our novel glycosylated angiotensin-(1-7) peptide Ang-1-6-O-Ser-Glc-NH2 (PNA5) as a therapy to treat VCID and to investigate circulating inflammatory biomarkers that may be involved. We demonstrate that PNA5 has greater brain penetration compared with the native angiotensin-(1-7) peptide. Moreover, after treatment with 1.0/mg/kg, s.c., for 21 days, PNA5 exhibits up to 10 days of sustained cognitive protective effects in our VCID/HF mice that last beyond the peptide half-life. PNA5 reversed object recognition impairment in VCID/HF mice and rescued spatial memory impairment. PNA5 activation of the Mas receptor results in a dose-dependent inhibition of ROS in human endothelial cells. Last, PNA5 treatment decreased VCID/HF-induced activation of brain microglia/macrophages and inhibited circulating tumor necrosis factor a, interleukin (IL)-7, and granulocyte cell-stimulating factor serum levels while increasing that of the anti-inflammatory cytokine IL-10. These results suggest that PNA5 is an excellent candidate and "first-inclass" therapy for treating VCID and other inflammation-related brain diseases.
According to the CDC (2017), more women than men have died from heart disease over the last 20-25... more According to the CDC (2017), more women than men have died from heart disease over the last 20-25 years. Yet, premenopausal women are protected against heart and cardiovascular disease (CVD) compared to age-matched men. The cellular and molecular mechanisms underlying the transition from premenopause/perimenopause (CVD-resistance) to postmenopause (CVD-susceptible) in women is unknown and is the focus of this project. The critical barrier impeding translational progress is the lack of appropriate models to study menopause. Most studies have used surgical removal of ovaries (ovariectomy) as a model of menopause; yet this technique poorly recapitulates the natural, physiological transition to menopause that 90% of women experience. We overcome this barrier with administration of the chemical, 4-vinylcyclohexene diepoxide (VCD), where we can mirror progressive ovarian failure and preserve the critical “perimenopause” transitional period, identical to humans. Using this model, we demons...
Given the limited treatment options for advanced heart failure, the intrinsic regenerative proper... more Given the limited treatment options for advanced heart failure, the intrinsic regenerative properties of stem cells have been evaluated for myocardial remodeling. Previous stem cells techniques for myocardiocyte remodeling have been limited by the low cellular retention. Presented is a hybrid approach for remodeling infarcted myocardium through implantation of allogeneic human amniotic fluid–derived mesenchymal stem cells within micronized human allograft-derived liquid matrix during the performance of transmyocardial revascularization (TMR). Given the induced increase in vascular density from TMR, we hypothesize that it may serve as a therapeutic delivery system for stem cell placement into damaged myocardium. We present a patient with ischemic cardiomyopathy and refractory angina, who clinically improved after this hybrid therapy of intraoperative TMR and placement of amniotic fluid–derived mesenchymal stem cells and liquid matrix within the TMR channels. Noninvasive testing of my...
Temporary mechanical circulatory support device without sternotomy has been highly advocated for ... more Temporary mechanical circulatory support device without sternotomy has been highly advocated for severe cardiogenic shock patient but little is known when coupled with amniotic stem cell therapy. This case reports the first dual therapy of temporary left ventricular extracorporeal device CentriMag with distal banding technique and human amniotic stem cell injection for treating a severe refractory cardiogenic shock of an 68-year-old female patient. A minimally-invasive off-pump LVAD was established by draining from the left ventricle and returning to the right axillary artery with distal arterial banding to prevent right upper extremity hyperperfusion. Amniotic stem cells were injected intramyocardially at the left ventricular apex, lateral wall, inferior wall, and right subclavian vein. The concomitant use of the temporary minimally-invasive off-pump CentriMag placement and stem cell therapy not only provided an alternative to cardiopulmonary bypass and full-median sternotomy proce...
Lungs donated after cardiac death (DCD) are an underutilized resource for a dwindling donor lung ... more Lungs donated after cardiac death (DCD) are an underutilized resource for a dwindling donor lung transplant pool. Our study investigates the potential of a novel preservation solution, Somah, to better preserve statically stored DCD lungs, for an extended time period, when compared to low-potassium dextran solution (LPD). We hypothesize that Somah is a metabolically superior organ preservation solution for hypothermic statically stored porcine DCD lungs, possibly improving lung transplant outcomes. Porcine DCD lungs (n = 3 per group) were flushed with and submerged in cold preservation solution. The lungs were stored up to 12 h, and samples were taken from lung tissue and the preservation medium throughout. Metabolomic and redox potential were analyzed using high performance liquid chromatography, mass spectrometry, and RedoxSYS®, comparing substrate and pathway utilization in both preservation solutions. Glutathione reduction was seen in Somah but not in LPD during preservation. Ca...
Patients with congestive heart failure (CHF) have increased hospital readmission rates and mortal... more Patients with congestive heart failure (CHF) have increased hospital readmission rates and mortality if they are concomitantly diagnosed with cognitive decline and memory loss. Accordingly, we developed a preclinical model of CHF-induced cognitive impairment with the goal of developing novel protective therapies against CHF related cognitive decline. CHF was induced by ligation of the left coronary artery to instigate a myocardial infarction (MI). By 4- and 8-weeks post-MI, CHF mice had approximately a 50% and 70% decline in ejection fraction as measured by echocardiography. At both 4- and 8-weeks post-MI, spatial memory performance in CHF mice as tested using the Morris water task was significantly impaired as compared with sham. In addition, CHF mice had significantly worse performance on object recognition when compared with shams as measured by discrimination ratios during the novel object recognition NOR task. At 8-weeks post-MI, a subgroup of CHF mice were given Angiotensin (A...
The heart undergoes extensive morphological, metabolic, and energetic remodeling in response to i... more The heart undergoes extensive morphological, metabolic, and energetic remodeling in response to inherited, or familial, hypertrophic cardiomyopathies (FHC). Myocyte contractile perturbations downstream of Ca 2+ , the so-called sarcomere-controlled mechanisms, may represent the earliest indicators of this remodeling. We can now state that the dynamics of cardiac contraction and relaxation during the progression of FHC are governed by downstream mechanisms, particularly the kinetics and energetics of actin and myosin interaction to drive the trajectory of pathological cardiac remodeling. This notion is unambiguously supported by elegant studies above linking inheritable FHCcausing mutations to cardiomyopathies, known to disturb contractile function and alter the energy landscape of the heart. Although studies examining the biophysical properties of cardiac myocytes with FHC-causing mutations have yielded a cellular and molecular understanding of myofilament function, this knowledge has had limited translational success. This is driven by a critical failure in elucidating an integrated and sequential link among the changing energy landscape, myofilament function, and initiated signaling pathways in response to FHC. Similarly, there continues to be a major gap in understanding the cellular and molecular mechanisms contributing to sex differences in FHC development and progression. The primary reason for this gap is a lack of a "unifying" or "central" hypothesis that integrates signaling cascades, energetics, sex and FHC.
American Journal of Physiology-Heart and Circulatory Physiology, 2016
Familial hypertrophic cardiomyopathy (HCM) is a disease of the sarcomere and may lead to hypertro... more Familial hypertrophic cardiomyopathy (HCM) is a disease of the sarcomere and may lead to hypertrophic, dilated, restrictive, and/or arrhythmogenic cardiomyopathy, congestive heart failure, or sudden cardiac death. We hypothesized that hearts from transgenic HCM mice harboring a mutant myosin heavy chain increase the energetic cost of contraction in a sex-specific manner. To do this, we assessed Ca2+sensitivity of tension and crossbridge kinetics in demembranated cardiac trabeculas from male and female wild-type (WT) and HCM hearts at an early time point (2 mo of age). We found a significant effect of sex on Ca2+sensitivity such that male, but not female, HCM mice displayed a decrease in Ca2+sensitivity compared with WT counterparts. The HCM transgene and sex significantly impacted the rate of force redevelopment by a rapid release-restretch protocol and tension cost by the ATPase-tension relationship. In each of these measures, HCM male trabeculas displayed a gain-of-function when c...
Journal of Biomedical Science and Engineering, 2016
Hospital inquired post-operative infections are a leading cause of morbidity and mortality in pat... more Hospital inquired post-operative infections are a leading cause of morbidity and mortality in patients receiving left ventricular assist devices. We present the case of a patient who acquired Candida albicans and Staphylococci infections following left ventricular assist device implantation. Use of standard antibiotics caused the infection to worsen, thus an amniotic membrane patch was used as a last-resort treatment. Within 6 weeks of the amniotic membrane patch treatment, the infection resolved, the wound appeared exceptionally clean upon inspection, and granulation tissue was present. After the infection resolved, a successful latissimusdorsi tissue flap procedure was completed and the patient made a full recovery.
It is well established that heart beat is triggered by electrical excitation, followed by an incr... more It is well established that heart beat is triggered by electrical excitation, followed by an increase in [Ca 2þ ] i and ensuing activation of myofilaments in cardiomyocytes. This property is the basis for the regulation of the heart with electric stimulators or chemical compounds that mediate Ca 2þ signaling. Recently, we found that microscopic heat pulses induce contractions in isolated rat cardiomyocytes without a rise in [Ca 2þ ] i (Oyama, K. et al., Biochem. Biophys. Res. Commun., 417, 607-612, 2012). Microscopic heat pulses produced by focusing infrared laser beam increase temperature of the extracellular solution near cardiomyocytes. In our experiments, a microscopic heat pulse (DT = 5 C for 0.5 sec) induced contractions at a basal temperature of 36 C. When heat pulses were repeatedly applied at 2.5 Hz, oscillatory contractions were observed. In contrast to the electric field stimulation, Ca 2þ transients were not detected during the course of contraction. Moreover, we confirmed that skinned cardiomyocytes are thermally activated in the Ca 2þ-free solution. To elucidate the molecular mechanism of thermal activation, microscopic heat pulses were applied to an in vitro motility assay system utilizing reconstituted thin filaments (rabbit skeletal actin filaments reconstituted with human cardiac tropomyosin and bovine cardiac troponin). Thin filaments started to move during heating in the absence of Ca 2þ , and most of filaments immediately stopped after switching the laser off, demonstrating that thin filaments can be thermally activated, presumably due to the weakening of the binding affinity of the troponin-tropomyosin complex with actin (Ishiwata, S., Biochim. Biophys. Acta, 534, 350-357, 1978). These results suggest that heat pulses can regulate cardiac contractions by shifting the ''on-off'' equilibrium in the thin filament toward the ''on'' state, without accompanying intracellular Ca 2þ transients.
Nebulin is a giant filamentous protein that is coextensive with the actin filaments of the skelet... more Nebulin is a giant filamentous protein that is coextensive with the actin filaments of the skeletal muscle sarcomere. Nebulin mutations are the main cause of nemaline myopathy (NEM), with typical adult patients having low expression of nebulin, yet the roles of nebulin in adult muscle remain poorly understood. To establish nebulin's functional roles in adult muscle we studied a novel conditional nebulin KO (Neb cKO) mouse model in which nebulin deletion was driven by the muscle creatine kinase (MCK)…
Medical Imaging 1995: Physiology and Function from Multidimensional Images, 1995
Electron beam computed tomography (EBCT) is a potentially useful modality to quantitate regional ... more Electron beam computed tomography (EBCT) is a potentially useful modality to quantitate regional pulmonary flow (RPF) with minimal invasiveness, in part because it has good spatial and temporal resolution. The present studies used a single compartment model of indicator transport and EBCT to measure regional tissue flow in the lungs of human subjects. The model postulates that flow is proportional to maximal enhancement and assumes complete tissue accumulation of indicator before significant indicator washout (WO). EBCT flow studies were retrospectively analyzed with respect to RPF in 10 adult patients who had undergone clinically indicated or research cardiovascular studies. Time density curves from the left atrial (LA) cavity and one-third segments of left (LL) and right (RL) lungs (A: anterior, M: middle, and P: posterior segments) were used to calculate RPF. Washout was determined as the percent of the LA curve at the time of peak parenchymal opacification using gamma curve fits to both tissue data and the LA curve data. Mean +/- standard deviation RPF in ml/min/ml was 0.8 +/- 0.4, 1.1 +/- 0.4, and 1.3 +/- 0.4 for A, M, and P respectively for one-third regions in the left lung. Similar results were found in the right lung. No difference in RPF was found when images were measured either by including the largest of visible parenchymal vessels or when such vessels were excluded. Flow in A of LL and RL was less than that in M or P. Average WO was about 10%, with a range of 0-41% of the LA curve area. There was no significant difference between one-third segment WO using pairwise comparison on the left and right sides when tested separately. RPF values were greater in the posterior vs anterior regions of these supine patients. In conclusion, EBCT can detect gravity related flow differences in the human lung. EBCT has potential for clinical assessment of absolute regional pulmonary flow determination in animals and man.
Proceedings of 16th Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Many elastic biologic structures are spherical or nearly so: their mechanics with regard to press... more Many elastic biologic structures are spherical or nearly so: their mechanics with regard to pressure and distending volume are not widely understood. Pressure (P) and volume (V) during inflation and deflation were determined in 9 rubber spheres with wall thickness ratio (WTR) ranging from 0.01 to 1.79. P rose with inflation: with more inflation P peaked and declined. The stress-length
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Papers by John Konhilas