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The Journal of Physiology Mar 2017
Topics: Microcirculation; Neovascularization, Physiologic
PubMed: 28078687
DOI: 10.1113/JP273786 -
Hypertension (Dallas, Tex. : 1979) Aug 2012
Review
Topics: Animals; Cardiovascular Diseases; Disease Models, Animal; Humans; Hypertension; Microcirculation; Phenotype; Risk Factors
PubMed: 22733471
DOI: 10.1161/HYPERTENSIONAHA.111.188482 -
Journal of Visualized Experiments : JoVE Oct 2022Inflammation and thrombosis are complex processes that occur primarily in the microcirculation. Although standard histology may provide insight into the end pathway for...
Inflammation and thrombosis are complex processes that occur primarily in the microcirculation. Although standard histology may provide insight into the end pathway for both inflammation and thrombosis, it is not capable of showing the temporal changes that occur throughout the time course of these processes. Intravital microscopy (IVM) is the use of live-animal imaging to gain temporal insight into physiologic processes in vivo. This method is particularly powerful when assessing cellular and protein interactions within the circulation due to the rapid and sequential events that are often necessary for these interactions to occur. While IVM is an extremely powerful imaging methodology capable of viewing complex processes in vivo, there are a number of methodological factors that are important to consider when planning an IVM study. This paper outlines the process of conducting intravital imaging of the liver, identifying important considerations and potential pitfalls that may arise. Thus, this paper describes the use of IVM to study platelet-leukocyte-endothelial interactions in liver sinusoids to study the relative contributions of each in different models of acute liver injury.
Topics: Mice; Animals; Intravital Microscopy; Leukocytes; Endothelium; Microcirculation; Liver; Inflammation
PubMed: 36282718
DOI: 10.3791/64239 -
Critical Care (London, England) 2005Microcirculatory dysfunction plays a pivotal role in the development of the clinical manifestations of severe sepsis. Prior to the advent of new imaging technologies,... (Review)
Review
Microcirculatory dysfunction plays a pivotal role in the development of the clinical manifestations of severe sepsis. Prior to the advent of new imaging technologies, clinicians had been limited in their ability to assess the microcirculation at the bedside. Clinical evidence of microcirculatory perfusion has historically been limited to physical examination findings or surrogates that could be derived from global parameters of oxygen transport. This review explores: (1) the clinical manifestations of severe sepsis that can be linked to microcirculatory dysfunction; (2) the relationship between conventional hemodynamic parameters and microcirculatory blood flow indices; (3) the incorporation of microcirculatory function into the definition of 'shock' in the sepsis syndrome; (4) the role of the microcirculation in oxygen transport; and (5) the potential impact of novel sepsis therapies on microcirculatory flow. Although the study of the microcirculation has long been the domain of basic science, newly developed imaging technologies, such as orthogonal polarization spectral imaging, have now given us the ability to directly visualize and analyze microcirculatory blood flow at the bedside, and see the microcirculatory response to therapeutic interventions. Disordered microcirculatory flow can now be associated with systemic inflammation, acute organ dysfunction, and increased mortality. Using new technologies to directly image microcirculatory blood flow will help define the role of microcirculatory dysfunction in oxygen transport and circulatory support in severe sepsis.
Topics: Hemodynamics; Humans; Logistic Models; Microcirculation; Models, Cardiovascular; Oxygen; Point-of-Care Systems; Regional Blood Flow; Sepsis; Vasodilator Agents
PubMed: 16168070
DOI: 10.1186/cc3744 -
Basic Research in Cardiology May 2009Myocardial perfusion is regulated by a variety of factors that influence arteriolar vasomotor tone. An understanding of the physiological and pathophysiological factors... (Review)
Review
Myocardial perfusion is regulated by a variety of factors that influence arteriolar vasomotor tone. An understanding of the physiological and pathophysiological factors that modulate coronary blood flow provides the basis for the judicious use of medications for the treatment of patients with coronary artery disease. Vasomotor properties of the coronary circulation vary among species. This review highlights the results of recent studies that examine the mechanisms by which the human coronary microcirculation is regulated in normal and disease states, focusing on diabetes. Multiple pathways responsible for myogenic constriction and flow-mediated dilation in human coronary arterioles are addressed. The important role of endothelium-derived hyperpolarizing factors, their interactions in mediating dilation, as well as speculation regarding the clinical significance are emphasized. Unique properties of coronary arterioles in human vs. other species are discussed.
Topics: Cardiovascular Physiological Phenomena; Coronary Circulation; Humans; Microcirculation
PubMed: 19190954
DOI: 10.1007/s00395-009-0775-y -
Intensive Care Medicine Jul 2014
Topics: Capillaries; Female; Humans; Male; Microcirculation; Shock, Septic; Skin
PubMed: 24871502
DOI: 10.1007/s00134-014-3345-1 -
Journal of Neurotrauma Apr 2002Impaired cerebral perfusion contributes to evolving posttraumatic tissue damage. Spontaneous reversibility of reduced perfusion within the first days after injury could...
Impaired cerebral perfusion contributes to evolving posttraumatic tissue damage. Spontaneous reversibility of reduced perfusion within the first days after injury could make a persisting impact on secondary tissue damage less likely and needs to be considered for possible therapeutic approaches. The present study was designed to characterize the temporal profile and impact of trauma severity on cortical perfusion and microcirculation during the first 48 h after controlled cortical impact injury (CCI). In 10 rats, pericontusional cortical perfusion and microcirculation using laser Doppler flowmetry (LDF) and orthogonal polarization spectral (OPS) imaging were assessed before, and at 4, 24, and 48 h after CCI. Influence of trauma severity was studied by varying the penetration depth of the impactor rod (0.5 vs. 1 mm), thereby inducing a less and a more severe contusion. Mean arterial blood pressure (MABP), arterial blood gases, and blood glucose were monitored. With unchanged MABP and paCO2, cortical perfusion and microcirculation were significantly impaired during the first 48 h following CCI. Hypoperfusion observed at 4 h related to vasoconstriction and microcirculatory stasis preceded a long-lasting phase of hyperperfusion at 24 and 48 h reflected by vasodilation and increased flow velocity in arterioles and venules. Hyperperfusion was mostly pronounced in rats with a less severe contusion. Following CCI, trauma severity markedly influences changes in pericontusional cortical perfusion and microcirculation. Overall, pericontusional cortical hypoperfusion observed within the early phase preceded a long lasting phase of hyperperfusion up to 48 h after CCI.
Topics: Animals; Cerebral Cortex; Cerebrovascular Circulation; Laser-Doppler Flowmetry; Microcirculation; Rats; Rats, Sprague-Dawley
PubMed: 11990347
DOI: 10.1089/08977150252932361 -
Neuron Nov 2002Brain drug development of either small molecule or large molecule (recombinant proteins, gene medicines) neurotherapeutics has been limited, owing to the restrictive... (Review)
Review
Brain drug development of either small molecule or large molecule (recombinant proteins, gene medicines) neurotherapeutics has been limited, owing to the restrictive transport properties of the brain microvasculature, which forms the blood-brain barrier (BBB) in vivo. Widespread drug delivery to the brain, while not feasible via craniotomy and intracerebral injection, is possible if the drug is delivered to brain via the transvascular route through the BBB. Novel brain drug delivery and drug targeting strategies can be developed from an understanding of the molecular and cellular biology of the brain microvascular and BBB transport processes.
Topics: Animals; Blood-Brain Barrier; Brain; Carrier Proteins; Central Nervous System Diseases; Drug Administration Routes; Endothelium, Vascular; Genetic Therapy; Humans; Microcirculation; Tight Junctions
PubMed: 12441045
DOI: 10.1016/s0896-6273(02)01054-1 -
Annals of Biomedical Engineering Nov 2013The three-dimensional spatial arrangement of the cortical microcirculatory system is critical for understanding oxygen exchange between blood vessels and brain cells. A...
The three-dimensional spatial arrangement of the cortical microcirculatory system is critical for understanding oxygen exchange between blood vessels and brain cells. A three-dimensional computer model of a 3 × 3 × 3 mm(3) subsection of the human secondary cortex was constructed to quantify oxygen advection in the microcirculation, tissue oxygen perfusion, and consumption in the human cortex. This computer model accounts for all arterial, capillary and venous blood vessels of the cerebral microvascular bed as well as brain tissue occupying the extravascular space. Microvessels were assembled with optimization algorithms emulating angiogenic growth; a realistic capillary bed was built with space filling procedures. The extravascular tissue was modeled as a porous medium supplied with oxygen by advection-diffusion to match normal metabolic oxygen demand. The resulting synthetic computer generated network matches prior measured morphometrics and fractal patterns of the cortical microvasculature. This morphologically accurate, physiologically consistent, multi-scale computer network of the cerebral microcirculation predicts the oxygen exchange of cortical blood vessels with the surrounding gray matter. Oxygen tension subject to blood pressure and flow conditions were computed and validated for the blood as well as brain tissue. Oxygen gradients along arterioles, capillaries and veins agreed with in vivo trends observed recently in imaging studies within experimental tolerances and uncertainty.
Topics: Cerebral Cortex; Cerebrovascular Circulation; Humans; Microcirculation; Models, Cardiovascular; Oxygen
PubMed: 23842693
DOI: 10.1007/s10439-013-0828-0 -
Asian Journal of Surgery Sep 2023The study explored the clinical efficacy of microcirculation-assisted blood flow adjustment in patients receiving venoarterial extracorporeal membrane oxygenation... (Randomized Controlled Trial)
Randomized Controlled Trial
Prognostic effects of microcirculation-assisted adjustment of venoarterial blood flow in extracorporeal membrane oxygenation: A prospective, pilot, randomized controlled trial.
OBJECTIVE
The study explored the clinical efficacy of microcirculation-assisted blood flow adjustment in patients receiving venoarterial extracorporeal membrane oxygenation (VA-ECMO).
METHODS
This prospective, pilot, randomized controlled trial was conducted from 2018 to 2021; enrolled patients were randomly assigned to the microcirculation or control group at a 1:1 ratio. Microcirculatory and clinical data were collected within 24 h (T1) and at 24-48 h (T2), 48-72 h (T3), and 72-96 h (T4) after ECMO initiation and were compared between the groups following the intention-to-treat (ITT) principle. The primary outcome was the Sequential Organ Failure Assessment (SOFA) score at T2. In addition to ITT analysis, analysis based on the as-treated (AT) principle was performed.
RESULTS
A total of 35 patients were enrolled in this study. At T2, the SOFA score did not significantly differ between the microcirculation and control groups (16 [14.8-17] vs. 16 [12.5-18], P = 0.782). Generalized estimating equation analysis demonstrated a significantly greater reduction in the SOFA score over time in the microcirculation-AT group than in the control-AT group (estimated difference: -0.767, standard error: 0.327, P = 0.019). The lactate level at T2 was significantly lower in the microcirculation-AT group (2.7 [2.0-3.6] vs. 4.1 [3.0-6.6] mmol/L, P = 0.029). No significant difference in the 30-day survival rate was noted between the groups.
CONCLUSION
This prospective pilot study demonstrated the feasibility of microcirculation-assisted VA-ECMO blood flow adjustment despite no significant clinical benefit for critically ill patients. More efforts in personnel training and newer technologies may help achieve microcirculation optimization.
Topics: Humans; Prognosis; Microcirculation; Extracorporeal Membrane Oxygenation; Prospective Studies; Pilot Projects
PubMed: 37002046
DOI: 10.1016/j.asjsur.2023.03.069