Article
Physiology
Richard J. Sove, Stephanie Milkovich, Hristo N. Nikolov, David W. Holdsworth, Christopher G. Ellis, Graham M. Fraser
Summary: In this study, a gas exchange system compatible with intravital microscopy was proposed for imposing gas perturbations to small localized regions in tissues that can be imaged using conventional inverted microscopes. The effectiveness of this system was demonstrated by manipulating oxygen concentrations in rat extensor digitorum longus muscle and measuring vascular responses, validating the localization of oxygen changes and tissue oxygenation. This approach can be used to study dynamic and spatial responses to local oxygen challenges in the microenvironment of skeletal muscle.
FRONTIERS IN PHYSIOLOGY
(2021)
Article
Optics
Julia Arciero, Brendan Fry, Amanda Albright, Grace Mattingly, Hannah Scanlon, Mandy Abernathy, Brent Siesky, Alice Verticchio Vercellin, Alon Harris
Summary: This mathematical model combines an image-based representation of retinal arterioles with a compartmental description of capillaries and venules to predict blood flow and oxygenation in the retinal microcirculation. Metabolic signals are calculated in each vessel according to blood and tissue oxygen levels, predicting a wide range of metabolic signals dependent on oxygen levels. The model highlights the importance of a whole-network approach to describe the metabolic status of the retina.
Review
Biochemistry & Molecular Biology
Pavel P. Tregub, Anton S. Averchuk, Tatyana Baranich, Maria Ryazanova, Alla B. Salmina
Summary: The remodeling of cerebral microvessels has a significant impact on brain plasticity and neurodegenerative diseases. Abnormal neoangiogenesis and microvascular regression are associated with blood-brain barrier breakdown, neuroinflammation, and dysfunction of the neurovascular unit. This review summarizes the mechanisms of blood vessel regression and pruning, and discusses novel approaches to modulating cerebral remodeling and preventing aberrant microvascular activity in chronic neurodegeneration.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Review
Biochemistry & Molecular Biology
Donna C. Kennedy, Barbara Coen, Antony M. Wheatley, Karl J. A. McCullagh
Summary: This article reviews the chick chorioallantoic membrane (CAM) assay model as an effective tool for studying microcirculation. The CAM assay is highlighted as a quick, low-cost, and reliable model that bridges the gap between in vitro cell studies and in vivo animal experiments. The article explores the benefits and limitations of the CAM assay, and discusses different techniques for analyzing angiogenesis.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Medicine, Research & Experimental
Dan-Yang Chen, Ning-He Sun, Xiang Chen, Jun-Jie Gong, Song-Tao Yuan, Zi-Zhong Hu, Nan-Nan Lu, Jakob Korbelin, Kohji Fukunaga, Qing-Huai Liu, Ying-Mei Lu, Feng Han
Summary: Semaphorin 3G plays a crucial role in vascular remodeling and improvement of ischemic retinopathy by enhancing healthy vascular network formation and promoting diseased vasculature regression. Loss of Sema3G exacerbates pathological angiogenesis in retinal vasculature. Sema3G coordinates the functional interaction between beta-catenin and VE-cadherin, leading to increased beta-catenin stability and aiding in vascular remodeling.
JOURNAL OF CLINICAL INVESTIGATION
(2021)
Review
Biochemistry & Molecular Biology
Chiara Ciaccio, Andrea Coletta, Massimo Coletta
Summary: The molecular mechanism of O-2 binding to hemoglobin has been critically reviewed in this paper, providing detailed insights into the process of O-2 uptake and release in the lungs and tissues. The relevance of structural-functional relationships in O-2 binding is emphasized, particularly in poorly vascularized tissues such as the retina, and strategies for optimizing oxygen supply to these tissues are briefly discussed.
MOLECULAR ASPECTS OF MEDICINE
(2022)
Article
Multidisciplinary Sciences
Peter M. Maloca, Philippe Valmaggia, Theresa Hartmann, Marlene Juedes, Pascal W. Hasler, Hendrik P. N. Scholl, Nora Denk
Summary: This study provides volumetric choroidal readings of healthy cynomolgus monkey eyes using OCT imaging, and analyzes the influence of sex and origin on choroidal volumes. The results show that monkey origin does not affect choroid volumes, while sex has a significant influence on choroidal volumes in the superior-inferior axis.
Article
Endocrinology & Metabolism
Jose T. Celaya-Alcala, Grace Lee, Amy F. Smith, Bohan Li, Sava Sakadzic, David A. Boas, Timothy W. Secomb
Summary: Advanced imaging techniques have allowed for the study of three-dimensional microvascular network structures. A computational method has been developed to estimate blood flow rates, oxygen levels, tissue perfusion, and oxygen extraction based on incomplete boundary conditions. Predictions show a broad distribution of tissue oxygen levels, consistent with experimental values, and indicate a potential for tissue hypoxia under certain conditions.
JOURNAL OF CEREBRAL BLOOD FLOW AND METABOLISM
(2021)
Article
Cardiac & Cardiovascular Systems
Antonio Gallo, Thomas Dietenbeck, Alain Giron, Michel Paques, Nadjia Kachenoura, Xavier Girerd
Summary: The study found that microvascular remodeling in the retina is mainly related to hypertension, while vascular growth is primarily associated with aging and hyperglycemia through non-invasive detection methods.
CLINICAL RESEARCH IN CARDIOLOGY
(2021)
Article
Neurosciences
Asher A. Mendelson, Stephanie Milkovich, Timothy Hunter, Raashi Vijay, Yun-Hee Choi, Shaun Milkovich, Edward Ho, Daniel Goldman, Christopher G. Ellis
Summary: The capillary module, traditionally thought to be the building block of complex capillary networks, fails to explain how blood flow is regulated in skeletal muscle. The concept of a capillary fascicle, consisting of interconnected modules, plays a crucial role in determining blood flow distribution in skeletal muscle. The findings provide direct evidence for microvascular flow regulation at the level of the capillary module, updating the paradigm for characterizing blood flow and red blood cell distribution in capillary networks.
JOURNAL OF PHYSIOLOGY-LONDON
(2021)
Article
Sport Sciences
Andrew C. Betik, Lewan Parker, Gunveen Kaur, Glenn D. Wadley, Michelle A. Keske
Summary: The study showed that a short session of whole-body vibration therapy significantly improves muscle microvascular blood flow in healthy individuals. While knee extension exercise provides a stronger stimulus, whole-body vibration can also effectively enhance microvascular blood flow.
MEDICINE AND SCIENCE IN SPORTS AND EXERCISE
(2021)
Article
Biochemistry & Molecular Biology
Jessica S. Yu, Neda Bagheri
Summary: The study examines how vascular structure and function influence emergent cell population behavior using an agent-based model. The model allows researchers to mix and match different cell agents, subcellular modules, and microenvironment components, showcasing the bilateral relationship between cells and nearby vasculature.
Article
Peripheral Vascular Disease
Anna Rogowska, Lukasz Obrycki, Zbigniew Kulaga, Claudia Kowalewska, Mieczyslaw Litwin
Summary: The study found that hypertensive children show signs of microcirculation remodeling and decreased neural layer of the retina, associated with hypertensive macrocirculation remodeling characterized by increased carotid intima-media thickness and elevated central systolic blood pressure.
Article
Biology
Farhad A. Amiri, Junfeng Zhang
Summary: Hematocrit plays a crucial role in oxygen transfer in the microvasculature. While a higher hematocrit increases the availability of oxygen, it also leads to slower red blood cell motion and reduced oxygen influx. Understanding these complex interactions is important for studying oxygen transport in microcirculation.
BULLETIN OF MATHEMATICAL BIOLOGY
(2023)
Article
Medicine, General & Internal
Tiziana Sampietro, Beatrice Dal Pino, Federico Bigazzi, Francesco Sbrana, Andrea Ripoli, Enrica Fontanelli, Mascia Pianelli, Roberta Luciani, Antonio Lepri, Giacomo Calzetti
Summary: After lipoprotein apheresis, there is a short-term significant increase in optic disk blood flow, similar to the response in coronary microcirculation. This suggests that ocular microcirculation may serve as a versatile biomarker for evaluating systemic microcirculatory health.
AMERICAN JOURNAL OF MEDICINE
(2023)
Article
Endocrinology & Metabolism
Ikbal Sencan, Tatiana Esipova, Kivilcim Kilic, Baoqiang Li, Michele Desjardins, Mohammad A. Yaseen, Hui Wang, Jason E. Porter, Sreekanth Kura, Buyin Fu, Timothy W. Secomb, David A. Boas, Sergei A. Vinogradov, Anna Devor, Sava Sakadzic
Summary: This study investigates the laminar profile of stimulus-induced intravascular partial pressure of oxygen (pO2) transients in fully awake mice. The results demonstrate that stimulus-induced changes in intravascular pO2 are consistent across cortical layers and show differences in response between veins and arteries, as well as differences from the response under anesthesia.
JOURNAL OF CEREBRAL BLOOD FLOW AND METABOLISM
(2022)
Review
Hematology
Tuhin K. Roy, Timothy W. Secomb
Summary: Impaired tissue oxygen delivery causing organ damage and failure in critically ill patients can occur despite normal systemic parameters due to heterogeneous microcirculation structure. Dynamic processes of structural adaptation and flow regulation in microvessels play a key role in redistributing flow according to metabolic needs for adequate tissue oxygenation. Restoration of endothelial cell function, including conducted responses, may be critical in restoring tissue oxygenation in critically ill patients.
Review
Medicine, General & Internal
Paolo B. Dominelli, Chad C. Wiggins, Tuhin K. Roy, Timothy W. Secomb, Timothy B. Curry, Michael J. Joyner
Summary: The oxygen transport cascade describes the physiological steps of bringing atmospheric oxygen into the body for consumption by metabolically active tissue, which is crucial for understanding exercise in health and disease. The review highlights each step of the oxygen transport cascade and draws parallels between elite athletes and clinical conditions in terms of oxygen transport cascade.
MAYO CLINIC PROCEEDINGS
(2021)
Article
Hematology
Brendan C. Fry, Timothy W. Secomb
Summary: The study analyzed the roles of RBC-derived and wall-derived mechanisms in metabolic blood flow regulation, finding that their combination may have better effects. The wall-derived mechanism may prevent hypoxia, while the RBC-derived mechanism can maintain the optimal tissue oxygen levels for function.
Article
Physiology
David W. Johnson, Tuhin K. Roy, Timothy W. Secomb
Summary: A theoretical model was used to predict the effects of hypoxic pulmonary vasoconstriction on pulmonary vascular resistance (PVR) across different vessel diameters, showing that vasoconstriction in larger upstream vessels plays a crucial role in the elevation of PVR during HPV.
JOURNAL OF APPLIED PHYSIOLOGY
(2021)
Article
Biochemical Research Methods
Jonathan P. Alberding, Timothy W. Secomb
Summary: The vasculature is a dynamic structure that responds to various physiological and pathological stimuli. Key responses in this process include angiogenesis, remodeling, and pruning. Theoretical models can simulate the formation of vascular networks and their physiological roles.
PLOS COMPUTATIONAL BIOLOGY
(2021)
Review
Physiology
Tuhin K. Roy, Timothy W. Secomb
Summary: In the vascular system, the heterogeneous parameters describing network structure, blood flow, and oxygen transport can strongly affect oxygen supply and organ function. These mechanisms have evolved to compensate for heterogeneity, involving long-term structural adaptation and short-term flow regulation. Restoration of endothelial function should be considered in clinical settings to address tissue hypoxemia and organ failure.
PHYSIOLOGICAL REPORTS
(2022)
Article
Biophysics
Michael J. J. Moulton, Timothy W. W. Secomb
Summary: In this study, a computationally efficient, biophysically based mathematical model is proposed to study the progression of diseases such as hypertension, systolic heart failure, and heart failure with preserved ejection fraction. The model includes four chambers of the heart, with the left ventricle represented by a low-order, wall volume-preserving model. The cardiac model is coupled with a wave propagation model for the aorta and a closed lumped-parameter circulation model. Changes in aortic properties due to aging are shown to affect pulse wave reflections, LV pressure-volume loops, and LV fiber stress and sarcomere shortening.
BIOMECHANICS AND MODELING IN MECHANOBIOLOGY
(2023)
Article
Biology
Madison Delmoe, Timothy W. Secomb
Summary: A simplified model for the electrophysiology of endothelial cells is used to investigate the conditions leading to bistability of membrane resting potential. The model considers the effects of inward-rectifying potassium (Kir) ion channels, whose current-voltage relationship exhibits a negative slope region and its maximum conductance depends on extracellular potassium concentration. The study presents a method for identifying the parameter space boundaries of background currents that correspond to bistability regions. The results reveal narrow bistability regions that depend on extracellular potassium concentration and define conditions for transitions between depolarized and hyperpolarized membrane states. These findings have implications for understanding the regulation of blood flow and conducted responses in the brain and other tissues.
MATHEMATICAL BIOSCIENCES
(2023)
Article
Biology
Katherine S. Williams, Timothy W. Secomb, Ardith W. El-Kareh
Summary: A mathematical model that describes the mammalian cell cycle is developed based on experimental data. The model includes variables for cycle tasks and controllers, and predicts distinct behaviors corresponding to different phases of the cell cycle. The model is autonomous, continuous in time, and includes mechanisms to prevent rereplication. It is robust to parameter changes and can be used to investigate the effects of extracellular factors on cell cycle progression.
JOURNAL OF THEORETICAL BIOLOGY
(2023)
Article
Hematology
Nien-Wen Hu, Banks M. Lomel, Elijah W. Rice, Mir Md Nasim Hossain, Malisa Sarntinoranont, Timothy W. Secomb, Walter L. Murfee, Peter Balogh
Summary: This study aimed to estimate segment-specific shear stresses in angiogenic networks. The results showed a significant variability of shear stresses along angiogenic capillaries, which provides new insights into the response of endothelial cells to segment-specific microenvironment during angiogenesis.
Article
Physiology
Kevin L. Webb, Michael J. Joyner, Chad C. Wiggins, Timothy W. Secomb, Tuhin K. Roy
Summary: This study investigates the effect of hemoglobin-oxygen affinity on the maximum oxygen uptake and utilization capacity at high altitudes using a mathematical model. The model predicts that increased hemoglobin-oxygen affinity leads to increased maximum oxygen uptake and utilization capacity above an altitude of approximately 4500 meters.
PHYSIOLOGICAL REPORTS
(2023)
Article
Neurosciences
Sara Djurich, Timothy W. Secomb
Summary: Neurovascular coupling refers to an increase in cerebral blood flow in response to increased neuronal activity. This study investigates the role of astrocyte endfeet in facilitating the diffusion of potassium ions from neurons to capillaries. The results suggest that direct diffusion of potassium ions through the extracellular space is a possible signaling mechanism for neurovascular coupling.
EUROPEAN JOURNAL OF NEUROSCIENCE
(2023)
Article
Physiology
Stephen H. Wright, Timothy W. Secomb
Summary: This article describes a mathematical model that calculates unique kinetic parameters (maximal rates of transport JMax and half-saturation constants Kt) of the process based on the time course of net substrate uptake into cells from several increasing concentrations. The method takes into account common complicating factors such as unstirred layers and carrier-mediated efflux in the experimental determination of transport kinetics.
AMERICAN JOURNAL OF PHYSIOLOGY-RENAL PHYSIOLOGY
(2022)