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result(s) for
"Neikirk, Kit"
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A Universal Approach to Analyzing Transmission Electron Microscopy with ImageJ
by
Glancy, Brian
,
Christensen, Trace A.
,
Abel, E. Dale
in
Alzheimer's disease
,
Amino acids
,
Animals
2021
Transmission electron microscopy (TEM) is widely used as an imaging modality to provide high-resolution details of subcellular components within cells and tissues. Mitochondria and endoplasmic reticulum (ER) are organelles of particular interest to those investigating metabolic disorders. A straightforward method for quantifying and characterizing particular aspects of these organelles would be a useful tool. In this protocol, we outline how to accurately assess the morphology of these important subcellular structures using open source software ImageJ, originally developed by the National Institutes of Health (NIH). Specifically, we detail how to obtain mitochondrial length, width, area, and circularity, in addition to assessing cristae morphology and measuring mito/endoplasmic reticulum (ER) interactions. These procedures provide useful tools for quantifying and characterizing key features of sub-cellular morphology, leading to accurate and reproducible measurements and visualizations of mitochondria and ER.
Journal Article
The Antioxidative Effects of Flavones in Hypertensive Disease
by
Neikirk, Kit
,
Ahmad, Taseer
,
Kirabo, Annet
in
Analysis
,
Animal models
,
Antigen-presenting cells
2023
Hypertension is the leading remediable risk factor for cardiovascular morbidity and mortality in the United States. Excess dietary salt consumption, which is a catalyst of hypertension, initiates an inflammatory cascade via activation of antigen-presenting cells (APCs). This pro-inflammatory response is driven primarily by sodium ions (Na+) transporting into APCs by the epithelial sodium channel (ENaC) and subsequent NADPH oxidase activation, leading to high levels of oxidative stress. Oxidative stress, a well-known catalyst for hypertension-related illness development, disturbs redox homeostasis, which ultimately promotes lipid peroxidation, isolevuglandin production and an inflammatory response. Natural medicinal compounds derived from organic materials that are characterized by their anti-inflammatory, anti-oxidative, and anti-mutagenic properties have recently gained traction amongst the pharmacology community due to their therapeutic effects. Flavonoids, a natural phenolic compound, have these therapeutic benefits and can potentially serve as anti-hypertensives. Flavones are a type of flavonoid that have increased anti-inflammatory effects that may allow them to act as therapeutic agents for hypertension, including diosmetin, which is able to induce significant arterial vasodilation in several different animal models. This review will focus on the activity of flavones to illuminate potential preventative and potential therapeutic mechanisms against hypertension.
Journal Article
Protocols for Generating Surfaces and Measuring 3D Organelle Morphology Using Amira
2021
High-resolution 3D images of organelles are of paramount importance in cellular biology. Although light microscopy and transmission electron microscopy (TEM) have provided the standard for imaging cellular structures, they cannot provide 3D images. However, recent technological advances such as serial block-face scanning electron microscopy (SBF-SEM) and focused ion beam scanning electron microscopy (FIB-SEM) provide the tools to create 3D images for the ultrastructural analysis of organelles. Here, we describe a standardized protocol using the visualization software, Amira, to quantify organelle morphologies in 3D, thereby providing accurate and reproducible measurements of these cellular substructures. We demonstrate applications of SBF-SEM and Amira to quantify mitochondria and endoplasmic reticulum (ER) structures.
Journal Article
Air pollutants as modulators of mitochondrial quality control in cardiovascular disease
2024
It is important to understand the effects of environmental factors such as air pollution on mitochondrial structure and function, especially when these changes increase cardiovascular disease risk. Although lifestyle choices directly determine many mitochondrial diseases, increasingly, it is becoming clear that the structure and function of mitochondria may be affected by pollutants found in the atmosphere (e.g., gases, pesticides herbicide aerosols, or microparticles). To date, the role of such agents on mitochondria and the potential impact on cardiovascular fitness is neglected. Here we offer a review of airborne stressors and pollutants, that may contribute to impairments in mitochondrial function and structure to cause heart disease.
Journal Article
Correction: Garza-Lopez et al. Protocols for Generating Surfaces and Measuring 3D Organelle Morphology Using Amira. Cells 2022, 11, 65
2023
In the original publication [...]
Journal Article
Cardiovascular hemodynamics in mice with tumor necrosis factor receptor—associated factor 2 mediated cytoprotection in the heart
by
Spencer, Elsie
,
Marshall, Andrea G.
,
Evans, Zoe
in
aortic impedance
,
Apoptosis
,
arterial and left ventricular elastance
2023
Many studies in mice have demonstrated that cardiac-specific innate immune signaling pathways can be reprogrammed to modulate inflammation in response to myocardial injury and improve outcomes. While the echocardiography standard parameters of left ventricular (LV) ejection fraction, fractional shortening, end-diastolic diameter, and others are used to assess cardiac function, their dependency on loading conditions somewhat limits their utility in completely reflecting the contractile function and global cardiovascular efficiency of the heart. A true measure of global cardiovascular efficiency should include the interaction between the ventricle and the aorta (ventricular-vascular coupling, VVC) as well as measures of aortic impedance and pulse wave velocity.
We measured cardiac Doppler velocities, blood pressures, along with VVC, aortic impedance, and pulse wave velocity to evaluate global cardiac function in a mouse model of cardiac-restricted low levels of TRAF2 overexpression that conferred cytoprotection in the heart.
While previous studies reported that response to myocardial infarction and reperfusion was improved in the TRAF2 overexpressed mice, we found that TRAF2 mice had significantly lower cardiac systolic velocities and accelerations, diastolic atrial velocity, aortic pressures, rate-pressure product, LV contractility and relaxation, and stroke work when compared to littermate control mice. Also, we found significantly longer aortic ejection time, isovolumic contraction and relaxation times, and significantly higher mitral early/atrial ratio, myocardial performance index, and ventricular vascular coupling in the TRAF2 overexpression mice compared to their littermate controls. We found no significant differences in the aortic impedance and pulse wave velocity.
While the reported tolerance to ischemic insults in TRAF2 overexpression mice may suggest enhanced cardiac reserve, our results indicate diminished cardiac function in these mice.
Journal Article
Endoplasmic Reticulum Stress in Hypertension and Salt Sensitivity of Blood Pressure
by
Balhara, Maria
,
Neikirk, Kit
,
Hinton, Antentor
in
Animals
,
Blood pressure
,
Blood Pressure - physiology
2024
Purpose of Review
Hypertension is a principal risk factor for cardiovascular morbidity and mortality, with its severity exacerbated by high sodium intake, particularly in individuals with salt-sensitive blood pressure. However, the mechanisms underlying hypertension and salt sensitivity are only partly understood. Herein, we review potential interactions in hypertension pathophysiology involving the immune system, endoplasmic reticulum (ER) stress, the unfolded protein response (UPR), and proteostasis pathways; identify knowledge gaps; and discuss future directions.
Recent Findings
Recent advancements by our research group and others reveal interactions within and between adaptive and innate immune responses in hypertension pathophysiology. The salt-immune-hypertension axis is further supported by the discovery of the role of dendritic cells in hypertension, marked by isolevuglandin (IsoLG) formation. Alongside these broadened understandings of immune-mediated salt sensitivity, the contributions of T cells to hypertension have been recently challenged by groups whose findings did not support increased resistance of Rag-1-deficient mice to Ang II infusion. Hypertension has also been linked to ER stress and the UPR. Notably, a holistic approach is needed because the UPR engages in crosstalk with autophagy, the ubiquitin proteasome, and other proteostasis pathways, that may all involve hypertension.
Summary
There is a critical need for studies to establish cause and effect relationships between ER stress and the UPR in hypertension pathophysiology in humans and to determine whether the immune system and ER stress function mainly to exacerbate or initiate hypertension and target organ injury. This review of recent studies proposes new avenues for future research for targeted therapeutic interventions.
Journal Article
Update on the Use of Pulse Wave Velocity to Measure Age-Related Vascular Changes
by
Neikirk, Kit
,
Reddy, Anilkumar K.
,
Marshall, Andrea G.
in
Aging
,
Arteries
,
Artificial Intelligence
2024
Purpose of Review
Pulse wave velocity (PWV) is an important and well-established measure of arterial stiffness that is strongly associated with aging. Age-related alterations in the elastic properties and integrity of arterial walls can lead to cardiovascular disease. PWV measurements play an important role in the early detection of these changes, as well as other cardiovascular disease risk factors, such as hypertension. This review provides a comprehensive summary of the current knowledge of the effects of aging on arterial stiffness, as measured by PWV.
Recent Findings
This review highlights recent findings showing the applicability of PWV analysis for investigating heart failure, hypertension, and other cardiovascular diseases, as well as cerebrovascular diseases and Alzheimer’s disease. It also discusses the clinical implications of utilizing PWV to monitor treatment outcomes, various challenges in implementing PWV assessment in clinical practice, and the development of new technologies, including machine learning and artificial intelligence, which may improve the usefulness of PWV measurements in the future.
Summary
Measuring arterial stiffness through PWV remains an important technique to study aging, especially as the technology continues to evolve. There is a clear need to leverage PWV to identify interventions that mitigate age-related increases in PWV, potentially improving CVD outcomes and promoting healthy vascular aging.
Journal Article
Mitochondrial heterogeneity and crosstalk in aging: Time for a paradigm shift?
by
Neikirk, Kit
,
Scudese, Estevão
,
Montano, Monty
in
Aging
,
Aging - genetics
,
Aging - physiology
2024
The hallmarks of aging have been influential in guiding the biology of aging research, with more recent and growing recognition of the interdependence of these hallmarks on age‐related health outcomes. However, a current challenge is personalizing aging trajectories to promote healthy aging, given the diversity of genotypes and lived experience. We suggest that incorporating heterogeneity—including intrinsic (e.g., genetic and structural) and extrinsic (e.g., environmental and exposome) factors and their interdependence of hallmarks—may move the dial. This editorial perspective will focus on one hallmark, namely mitochondrial dysfunction, to exemplify how consideration of heterogeneity and interdependence or crosstalk may reveal new perspectives and opportunities for personalizing aging research. To this end, we highlight heterogeneity within mitochondria as a model. This editorial highlights intrinsic and extrinsic factors that may contribute to mitochondrial heterogeneity and quality control mechanisms. As depicted in the graphical , these factors may affect mitochondrial metabolism, mitochondrial structure, mitochondrial quality control, crosstalk with other organelles, mitochondrial DNA quality, and epigenetic regulation, pluralistically affecting the hallmarks of aging.
Journal Article
BNIP3 as a new tool to promote healthy brain aging
by
Neikirk, Kit
,
Hinton, Antentor
,
Marshall, Andrea G.
in
age‐related pathology
,
Aging
,
Alzheimer's disease
2024
The article “Neuronal induction of BNIP3‐mediated mitophagy slows systemic aging in Drosophila” reveals BCL2‐interacting protein 3 as a therapeutic target to counteract brain aging and prolong overall organismal health with age. In this spotlight, we consider the roles of BNIP3, a mitochondrial outer membrane protein, in the adult nervous system, including its induction of mitophagy and prevention of dysfunctional mitochondria in the aged brain. Implications for other tissue types to reduce the burden of aging are further considered. GRAPHICAL TEXT Showing pathways across aging and altered pathways with the addition of BNIP3.
Journal Article