Articles de revues sur le sujet « Intravital microscopy techniques »
Pour voir les autres types de publications sur ce sujet consultez le lien suivant : Intravital microscopy techniques.
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleurs articles de revues pour votre recherche sur le sujet « Intravital microscopy techniques ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les articles de revues sur diverses disciplines et organisez correctement votre bibliographie.
1
Choi, Myunghwan, Sheldon J. J. Kwok et Seok Hyun Yun. « In Vivo Fluorescence Microscopy : Lessons From Observing Cell Behavior in Their Native Environment ». Physiology 30, no 1 (janvier 2015) : 40–49. http://dx.doi.org/10.1152/physiol.00019.2014.
Texte intégralRésumé :
Microscopic imaging techniques to visualize cellular behaviors in their natural environment play a pivotal role in biomedical research. Here, we review how recent technical advances in intravital microscopy have enabled unprecedented access to cellular physiology in various organs of mice in normal and diseased states.
2
Norman, Keith. « Techniques : Intravital microscopy – a method for investigating disseminated intravascular coagulation ? » Trends in Pharmacological Sciences 26, no 6 (juin 2005) : 327–32. http://dx.doi.org/10.1016/j.tips.2005.04.002.
Texte intégral
3
Jain, Rohit, Shweta Tikoo et Wolfgang Weninger. « Recent advances in microscopic techniques for visualizing leukocytes in vivo ». F1000Research 5 (19 mai 2016) : 915. http://dx.doi.org/10.12688/f1000research.8127.1.
Texte intégralRésumé :
Leukocytes are inherently motile and interactive cells. Recent advances in intravital microscopy approaches have enabled a new vista of their behavior within intact tissues in real time. This brief review summarizes the developments enabling the tracking of immune responses in vivo.
4
Costanzo, Vincenzo, et Michele Costanzo. « Intravital Imaging with Two-Photon Microscopy : A Look into the Kidney ». Photonics 9, no 5 (27 avril 2022) : 294. http://dx.doi.org/10.3390/photonics9050294.
Texte intégralRésumé :
Fluorescence microscopy has represented a crucial technique to explore the cellular and molecular mechanisms in the field of biomedicine. However, the conventional one-photon microscopy exhibits many limitations when living samples are imaged. The new technologies, including two-photon microscopy (2PM), have considerably improved the in vivo study of pathophysiological processes, allowing the investigators to overcome the limits displayed by previous techniques. 2PM enables the real-time intravital imaging of the biological functions in different organs at cellular and subcellular resolution thanks to its improved laser penetration and less phototoxicity. The development of more sensitive detectors and long-wavelength fluorescent dyes as well as the implementation of semi-automatic software for data analysis allowed to gain insights in essential physiological functions, expanding the frontiers of cellular and molecular imaging. The future applications of 2PM are promising to push the intravital microscopy beyond the existing limits. In this review, we provide an overview of the current state-of-the-art methods of intravital microscopy, focusing on the most recent applications of 2PM in kidney physiology.
5
Vinegoni, Claudio, Aaron D. Aguirre, Sungon Lee et Ralph Weissleder. « Imaging the beating heart in the mouse using intravital microscopy techniques ». Nature Protocols 10, no 11 (22 octobre 2015) : 1802–19. http://dx.doi.org/10.1038/nprot.2015.119.
Texte intégral
6
Hickey, Michael J., et Paul Kubes. « Use of Intra Vital Microscopy to Analyze Leukocyte Rolling and Adhesion In Vivo ». Microscopy and Microanalysis 3, S2 (août 1997) : 323–24. http://dx.doi.org/10.1017/s1431927600008503.
Texte intégralRésumé :
Inflammation is a vital process by which the body is able to fight infection and heal wounded tissue. However inappropriate control of inflammation is responsible for a wide range of pathologies (e.g. rheumatoid arthritis, inflammatory bowel disease). One of the hallmark features of inflammation, and one of the key pathogenic mechanisms in inflammatory disorders is leukocyte recruitment. Therefore understanding the molecular mechanisms by which leukocytes travel from the bloodstream to the extravascular tissue is of great importance.Evidence suggests that there is a cascade of complex interactions between leukocytes and endothelium that to be fully understood must be studied on-line rather than using endpoint readouts such as tissue levels of leukocyte enzymes (myeloperoxidase) or histological techniques. A number of laboratories, including our own, have used a technique known as intravital microscopy to directly visualize leukocyte trafficking in individual vessels in a range of tissues, in an attempt to gain a better understanding of the mechanisms of leukocyte recruitment. Intravital microscopy entails microscopic examination of living tissues.
7
Torres Filho, Ivo P., James Terner, Roland N. Pittman, Leonardo G. Somera et Kevin R. Ward. « Hemoglobin oxygen saturation measurements using resonance Raman intravital microscopy ». American Journal of Physiology-Heart and Circulatory Physiology 289, no 1 (juillet 2005) : H488—H495. http://dx.doi.org/10.1152/ajpheart.01171.2004.
Texte intégralRésumé :
A system is described for in vivo noninvasive measurements of hemoglobin oxygen saturation (HbO2Sat) at the microscopic level. The spectroscopic basis for the application is resonant Raman enhancement of Hb in the violet/ultraviolet region, allowing simultaneous identification of oxy- and deoxyhemoglobin with the same excitation wavelength. The heme vibrational bands are well known, but the technique has never been used to determine microvascular HbO2Sat in vivo. A diode laser light (power: 0.3 mW) was focused onto sample areas 15–30 μm in diameter. Raman spectra were obtained in backscattering geometry by using a microscope coupled to a spectrometer and a cooled detector. Calibration was performed in vitro by using glass capillaries containing blood at several Hb concentrations, equilibrated at various oxygen tensions. HbO2Sat was estimated using the Raman band intensities at 1,360 and 1,375 cm−1. Glass capillary path length and Hb concentration had no effect on HbO2Sat estimated from Raman spectra. In vivo observations were made in blood flowing in microvessels of the rat mesentery. The Hb Raman peaks observed in oxygenated and deoxygenated blood were consistent with earlier Raman studies that used Hb solutions and isolated cells. The method allowed HbO2Sat determinations in the whole range of arterioles, venules, and capillaries. Tissue transillumination allowed diameter and erythrocyte velocity measurements in the same vessels. Raman microspectroscopy offers distinct advantages over other currently used techniques by providing noninvasive and reliable in vivo determinations of HbO2Sat in thin tissues as well as in solid organs and tissues, which are unsuitable for techniques requiring transillumination.
8
Lindbom, Lennart, et Ellinor Kenne. « Imaging inflammatory plasma leakage in vivo ». Thrombosis and Haemostasis 105, no 05 (2011) : 783–89. http://dx.doi.org/10.1160/th10-10-0635.
Texte intégralRésumé :
SummaryIncreased vascular permeability and consequent plasma leakage from postcapillary venules is a cardinal sign of inflammation. Although the movement of plasma constituents from the vasculature to the affected tissue aids in clearing the inflammatory stimulus, excessive plasma extravasation can lead to hospitalisation or death in cases such as influenza-induced pneumonia, burns or brain injury. The use of intravital imaging has significantly contributed to the understanding of the mechanisms controlling the vascular permeability alterations that occur during inflammation. Today, intravital imaging can be performed using optical and non-optical techniques. Optical techniques, which are generally used in experimental settings, include traditional intravital fluorescence microscopy and near-infrared fluorescence imaging. Magnetic resonance (MRI) and radioisotopic imaging are used mainly in the clinical setting, but are increasingly used in experimental work, and can detect plasma leakage without optics. Although these methods are all able to visualise inflammatory plasma leakage in vivo, the spatial and temporal resolution differs between the techniques. In addition, they vary with regards to invasiveness and availability. This overview discusses the use of imaging techniques in the visualisation of inflammatory plasma leakage.
9
Hato, Takashi, Allon N. Friedman, Henry Mang, Zoya Plotkin, Shataakshi Dube, Gary D. Hutchins, Paul R. Territo et al. « Novel application of complementary imaging techniques to examine in vivo glucose metabolism in the kidney ». American Journal of Physiology-Renal Physiology 310, no 8 (15 avril 2016) : F717—F725. http://dx.doi.org/10.1152/ajprenal.00535.2015.
Texte intégralRésumé :
The metabolic status of the kidney is a determinant of injury susceptibility and a measure of progression for many disease processes; however, noninvasive modalities to assess kidney metabolism are lacking. In this study, we employed positron emission tomography (PET) and intravital multiphoton microscopy (MPM) to assess cortical and proximal tubule glucose tracer uptake, respectively, following experimental perturbations of kidney metabolism. Applying dynamic image acquisition PET with 2-18fluoro-2-deoxyglucose (18F-FDG) and tracer kinetic modeling, we found that an intracellular compartment in the cortex of the kidney could be distinguished from the blood and urine compartments in animals. Given emerging literature that the tumor suppressor protein p53 is an important regulator of cellular metabolism, we demonstrated that PET imaging was able to discern a threefold increase in cortical 18F-FDG uptake following the pharmacological inhibition of p53 in animals. Intravital MPM with the fluorescent glucose analog 2-[ N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose (2-NBDG) provided increased resolution and corroborated these findings at the level of the proximal tubule. Extending our observation of p53 inhibition on proximal tubule glucose tracer uptake, we demonstrated by intravital MPM that pharmacological inhibition of p53 diminishes mitochondrial potential difference. We provide additional evidence that inhibition of p53 alters key metabolic enzymes regulating glycolysis and increases intermediates of glycolysis. In summary, we provide evidence that PET is a valuable tool for examining kidney metabolism in preclinical and clinical studies, intravital MPM is a powerful adjunct to PET in preclinical studies of metabolism, and p53 inhibition alters basal kidney metabolism.
10
ANTONIOS, Tarek F. T., Fraser E. M. RATTRAY, Donald R. J. SINGER, Nirmala D. MARKANDU, Peter S. MORTIMER et Graham A. MACGREGOR. « Maximization of skin capillaries during intravital video-microscopy in essential hypertension : comparison between venous congestion, reactive hyperaemia and core heat load tests ». Clinical Science 97, no 4 (16 septembre 1999) : 523–28. http://dx.doi.org/10.1042/cs0970523.
Texte intégralRésumé :
Intravital capillary video-microscopy is a dynamic method for studying skin capillaries. The technique of direct intravital microscopy (without dyes) depends on the presence of red blood cells inside capillaries for their identification. The aim of the present study was to compare different techniques to try to establish the best method for maximizing the number of visible perfused capillaries during intravital capillary microscopy. We compared the effects of venous congestion with those of post-occlusive reactive hyperaemia (Study 1). We also investigated venous congestion followed first by post-occlusive reactive hyperaemia and then by a core heat load test (Study 2). Finally we investigated venous congestion followed by post-occlusive reactive hyperaemia combined with venous congestion (Study 3). In Study 1, capillary density increased with venous congestion from a baseline value of 74±2 (mean±S.E.M.) per field to 82±3 per field (P< 0.0001; analysis of variance). With reactive hyperaemia, there was an apparent decrease in visible capillary density to 69±2 per field. In Study 2, baseline capillary density was 69±4 per field, and this increased significantly with venous congestion to 74±4 per field (P = 0.01). With both reactive hyperaemia and core heat load, the apparent density was 62±4 per field. In Study 3 the baseline density was 70±2 per field, and this increased significantly with venous congestion to 80±3 per field (P< 0.0001). With reactive hyperaemia combined with venous congestion, the density was 81±3 per field (P = 0.328 compared with venous congestion alone). The results show that venous congestion at 60 mmHg for 2 min is the most effective method for visualization of the maximal number of perfused skin capillaries during intravital video-microscopy.
11
de Buhr, Nicole, et Maren von Köckritz-Blickwede. « How Neutrophil Extracellular Traps Become Visible ». Journal of Immunology Research 2016 (2016) : 1–13. http://dx.doi.org/10.1155/2016/4604713.
Texte intégralRésumé :
Neutrophil extracellular traps (NETs) have been identified as a fundamental innate immune defense mechanism against different pathogens. NETs are characterized as released nuclear DNA associated with histones and granule proteins, which form an extracellular web-like structure that is able to entrap and occasionally kill certain microbes. Furthermore, NETs have been shown to contribute to several noninfectious disease conditions when released by activated neutrophils during inflammation. The identification of NETs has mainly been succeeded by various microscopy techniques, for example, immunofluorescence microscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Since the last years the development and improvement of new immunofluorescence-based techniques enabled optimized visualization and quantification of NETs. On the one handin vitrolive-cell imaging led to profound new ideas about the mechanisms involved in the formation and functionality of NETs. On the other hand different intravital,in vivo, andin situmicroscopy techniques led to deeper insights into the role of NET formation during health and disease. This paper presents an overview of the main used microscopy techniques to visualize NETs and describes their advantages as well as disadvantages.
12
Schweizer, R., K. Merz, S. Schlosser, T. Spanholtz, C. Contaldo, J. V. Stein, V. Enzmann, P. Giovanoli, D. Erni et J. A. Plock. « Morphology and Hemodynamics during Vascular Regeneration in Critically Ischemic Murine Skin Studied by Intravital Microscopy Techniques ». European Surgical Research 47, no 4 (2011) : 222–30. http://dx.doi.org/10.1159/000333088.
Texte intégral
13
Schnabel, Christian, Maria Gaertner et Edmund Koch. « Measurement of lung tissue dynamics in artificially ventilated rats with optical coherence tomography ». Current Directions in Biomedical Engineering 3, no 2 (7 septembre 2017) : 79–81. http://dx.doi.org/10.1515/cdbme-2017-0017.
Texte intégralRésumé :
AbstractDiseases of lung tissue and the airways become a major task for medical care and health care systems in modern industrial countries in the future. Suitable treatment methods and strategies for lung support and artificial ventilation are of dare need. Besides the obvious importance as life-saving intervention, the effects of usually used over-pressure ventilation onto the sensitive alveolar tissue are insufficiently understood. Therefore, it is of great interest to characterize lung tissue during artificial ventilation at the alveolar level. Those measurements can be used to link micromechanics of alveolar structures to mechanical properties of the whole lung like compliance and resistance measured at the ventilator device. This can be done only in animal experiments due to the fact that imaging techniques used in human diagnostics like CT or MRT fail to resolve alveolar tissue structures. The disadvantage of high-resolution techniques like optical coherence tomography (OCT) or intravital microscopy (IVM) is the need of a surgical access to the lung due to the limitation in penetration depth of these techniques. Furthermore, imaging dynamic processes with high-resolution imaging techniques during uninterrupted artificial ventilation is a challenging task. In this study, we present a measurement setup for combined imaging of conventional pressure-controlled ventilated rats and the visualization of volume changes of alveolar structures during one cycle of breath. A custom-made OCT system in combination with a triggered scanning algorithm was used to acquire time-resolved 3D OCT image data. Furthermore, this system was combined with a self-adapting autofocus function for intravital microscopy to track the lung surface keeping the tissue in focal plane. The combination of new dynamic measurement modes for OCT and IVM allows new insights into alveolar tissue and will promote the understanding of mechanical behavior during artificial ventilation.
14
Wisniewski, Emily O., Panagiotis Mistriotis, Kaustav Bera, Robert A. Law, Jitao Zhang, Milos Nikolic, Michael Weiger et al. « Dorsoventral polarity directs cell responses to migration track geometries ». Science Advances 6, no 31 (juillet 2020) : eaba6505. http://dx.doi.org/10.1126/sciadv.aba6505.
Texte intégralRésumé :
How migrating cells differentially adapt and respond to extracellular track geometries remains unknown. Using intravital imaging, we demonstrate that invading cells exhibit dorsoventral (top-to-bottom) polarity in vivo. To investigate the impact of dorsoventral polarity on cell locomotion through different confining geometries, we fabricated microchannels of fixed cross-sectional area, albeit with distinct aspect ratios. Vertical confinement, exerted along the dorsoventral polarity axis, induces myosin II–dependent nuclear stiffening, which results in RhoA hyperactivation at the cell poles and slow bleb-based migration. In lateral confinement, directed perpendicularly to the dorsoventral polarity axis, the absence of perinuclear myosin II fails to increase nuclear stiffness. Hence, cells maintain basal RhoA activity and display faster mesenchymal migration. In summary, by integrating microfabrication, imaging techniques, and intravital microscopy, we demonstrate that dorsoventral polarity, observed in vivo and in vitro, directs cell responses in confinement by spatially tuning RhoA activity, which controls bleb-based versus mesenchymal migration.
15
Maiques, Oscar, Mirella Georgouli et Victoria Sanz-Moreno. « Recent advances in tissue imaging for cancer research ». F1000Research 8 (25 novembre 2019) : 1980. http://dx.doi.org/10.12688/f1000research.19037.1.
Texte intégralRésumé :
Image analysis in clinical research has evolved at fast pace in the last decade. This review discusses basic concepts ranging from immunohistochemistry to advanced techniques such as multiplex imaging, digital pathology, flow cytometry and intravital microscopy. Tissue imaging ex vivo is still one of the gold-standards in the field due to feasibility. We describe here different protocols and applications of digital analysis providing basic and clinical researchers with an overview on how to analyse tissue images. In vivo imaging is not accessible to researchers; however, it provides invaluable dynamic information easily. Overall, we discuss a plethora of techniques that - when combined - constitute a powerful platform for basic and translational cancer research.
16
Subhash, Hrebesh M. « Biophotonics Modalities for High-Resolution Imaging of Microcirculatory Tissue Beds Using Endogenous Contrast : A Review on Present Scenario and Prospects ». International Journal of Optics 2011 (2011) : 1–20. http://dx.doi.org/10.1155/2011/293684.
Texte intégralRésumé :
The microcirculation is a complex system, and the visualization of microcirculation has great significance in improving our understanding of pathophysiological processes in various disease conditions, in both clinical and fundamental studies. A range of techniques are available or emerging for investigating different aspect of the microcirculation in animals and humans. This paper reviews the recent developments in the field of high-resolution and high-sensitive optical imaging of microcirculatory tissue beds, emphasizing technologies that utilize the endogenous contrast mechanism. Optical imaging techniques such as intravital microscopy, Capillaroscopy, laser Doppler perfusion imaging, laser speckle perfusion imaging, polarization spectroscopy, photo-acoustic tomography, and various implementations of optical coherence tomography based on Doppler and speckle contrast imaging are presented together with their prospectives and challenges.
17
Lawler, Cindy, William A. Suk, Bruce R. Pitt, Claudette M. St Croix et Simon C. Watkins. « Multimodal optical imaging ». American Journal of Physiology-Lung Cellular and Molecular Physiology 285, no 2 (août 2003) : L269—L280. http://dx.doi.org/10.1152/ajplung.00424.2002.
Texte intégralRésumé :
The recent resurgence of interest in the use of intravital microscopy in lung research is a manifestation of extraordinary progress in visual imaging and optical microscopy. This review evaluates the tools and instrumentation available for a number of imaging modalities, with particular attention to recent technological advances, and addresses recent progress in use of optical imaging techniques in basic pulmonary research. 1 Limitations of existing methods and anticipated future developments are also identified. Although there have also been major advances made in the use of magnetic resonance imaging, positron emission tomography, and X-ray and computed tomography to image intact lungs and while these technologies have been instrumental in advancing the diagnosis and treatment of patients, the purpose of this review is to outline developing optical methods that can be evaluated for use in basic research in pulmonary biology.
18
LaRouere, M. J., J. S. Sillman, A. L. Nuttall et J. M. Miller. « A Comparison of Laser Doppler and Intravital Microscopic Measures of Cochlear Blood Flow ». Otolaryngology–Head and Neck Surgery 101, no 3 (septembre 1989) : 375–84. http://dx.doi.org/10.1177/019459988910100311.
Texte intégralRésumé :
Many inner ear disorders may be caused by alterations in cochlear blood flow (CBF). However, each measurement technique used to monitor CBF has limitations in examining the relationship between otopathologic states and blood flow. This study Investigates laser Doppler flowmetry (LDF) and its fundamental drawback: The unknown relationship of LDF output to actual CBF. LDF readings are directly compared with concurrent intravital microscopy (IVM) measures of erythrocyte velocity in the lateral wall of the guinea pig cochlea. Positive end expiratory pressure, spontaneous respiration of 5% and 10% carbon dioxide, phenylephrine, and direct electrical stimulation of the cochlea were used to manipulate CBF. High, positive correlations were found between simultaneous LDF and IVM measurements of CBF. In addition, the study demonstrated that current microdissection techniques used to perform IVM do not cause changes in CBF. IVM measurements of CBF are a more sensitive indicator of CBF changes than are LDF measures. Despite the high correlation between measurement techniques within a single manipulation, simultaneous LDF and IVM measurements differed between manipulations. This may reflect regional changes in CBF affected by these manipulations and differences in the sampled vascular beds contributing to these two measures. It is unlikely that a single calibration factor can be defined that would allow the conversion of LDF output to actual units of blood flow across different manipulations used to alter CBF.
19
Liebig, Marie, Alireza Hassanzada, Malte Kämmerling, Berit Genz, Brigitte Vollmar et Kerstin Abshagen. « Microcirculatory disturbances and cellular changes during progression of hepatic steatosis to liver tumors ». Experimental Biology and Medicine 243, no 1 (24 octobre 2017) : 1–12. http://dx.doi.org/10.1177/1535370217738730.
Texte intégralRésumé :
Non-alcoholic fatty liver disease is closely associated with metabolic syndrome and comprises a pathological spectrum of liver disease ranging from steatosis to steatohepatitis and can progress to fibrosis/cirrhosis and hepatocellular carcinoma. In 2013, a mouse model was described that mimics non-alcoholic fatty liver disease progression from steatohepatitis to tumors in a short time span and with high incidence. As microcirculatory disturbances play a crucial role in liver disease, the suitability of the steatosis-inflammation-tumor model for microcirculatory studies was assessed. Herein, we present a comprehensive view on morphological, microvascular, cellular, and functional aspects of non-alcoholic fatty liver disease progression in the steatosis-inflammation-tumor model using intravital microscopy, biochemical, and histological techniques. Mice develop steatohepatitis, mild fibrosis, and liver tumors at ages of 6, 12, and 20 weeks, respectively. Non-alcoholic fatty liver disease progression was accompanied by several general aspects of disease severity like increasing liver/body weight index, non-alcoholic fatty liver disease activity score, and hepatocellular apoptosis. Intravital microscopic analysis revealed significant changes in hepatic microcirculation with increasing structural alterations, elevated leukocyte adherence, and impaired nutritive perfusion. Non-alcoholic fatty liver disease was further characterized by a lower sinusoidal density with a striking rise at 20 weeks. The characteristic microcirculatory changes make the model a convenient tool for analysis of microcirculation during progression from steatosis to liver tumor. Impact statement Significant alterations of microcirculation contribute to progression of NAFLD, a chronic liver disease with increasing medical and socio-economic impact. Characterization of microcirculation in a NAFLD model reflecting all relevant stages of disease progression was still missing. Thus, we evaluated microcirculatory and cellular changes in a steatosis-inflammation-tumor model using in vivo microscopy. Analyses revealed increasing structural alterations, elevated leukocyte-endothelial interaction, and impaired nutritive perfusion. Thus, this model is suitable for further studies investigating therapeutic approaches targeting these progressive microcirculatory disturbances.
20
Dickson, Kayle, Hajer Malitan et Christian Lehmann. « Imaging of the Intestinal Microcirculation during Acute and Chronic Inflammation ». Biology 9, no 12 (26 novembre 2020) : 418. http://dx.doi.org/10.3390/biology9120418.
Texte intégralRésumé :
Because of its unique microvascular anatomy, the intestine is particularly vulnerable to microcirculatory disturbances. During inflammation, pathological changes in blood flow, vessel integrity and capillary density result in impaired tissue oxygenation. In severe cases, these changes can progress to multiorgan failure and possibly death. Microcirculation may be evaluated in superficial tissues in patients using video microscopy devices, but these techniques do not allow the assessment of intestinal microcirculation. The gold standard for the experimental evaluation of intestinal microcirculation is intravital microscopy, a technique that allows for the in vivo examination of many pathophysiological processes including leukocyte-endothelial interactions and capillary blood flow. This review provides an overview of changes in the intestinal microcirculation in various acute and chronic inflammatory conditions. Acute conditions discussed include local infections, severe acute pancreatitis, necrotizing enterocolitis and sepsis. Inflammatory bowel disease and irritable bowel syndrome are included as examples of chronic conditions of the intestine.
21
Tilbury, Karissa, et Paul J. Campagnola. « Applications of Second-Harmonic Generation Imaging Microscopy in Ovarian and Breast Cancer ». Perspectives in Medicinal Chemistry 7 (janvier 2015) : PMC.S13214. http://dx.doi.org/10.4137/pmc.s13214.
Texte intégralRésumé :
In this perspective, we discuss how the nonlinear optical technique of second-harmonic generation (SHG) microscopy has been used to greatly enhance our understanding of the tumor microenvironment (TME) of breast and ovarian cancer. Striking changes in collagen architecture are associated with these epithelial cancers, and SHG can image these changes with great sensitivity and specificity with submicrometer resolution. This information has not historically been exploited by pathologists but has the potential to enhance diagnostic and prognostic capabilities. We summarize the utility of image processing tools that analyze fiber morphology in SHG images of breast and ovarian cancer in human tissues and animal models. We also describe methods that exploit the SHG physical underpinnings that are effective in delineating normal and malignant tissues. First we describe the use of polarization-resolved SHG that yields metrics related to macromolecular and supramolecular structures. The coherence and corresponding phase-matching process of SHG results in emission directionality (forward to backward), which is related to sub-resolution fibrillar assembly. These analyses are more general and more broadly applicable than purely morphology-based analyses; however, they are more computationally intensive. Intravital imaging techniques are also emerging that incorporate all of these quantitative analyses. Now, all these techniques can be coupled with rapidly advancing miniaturization of imaging systems to afford their use in clinical situations including enhancing pathology analysis and also in assisting in real-time surgical determination of tumor margins.
22
Kamoun, Walid S., Carsten D. Ley, Christian T. Farrar, Annique M. Duyverman, Johanna Lahdenranta, Delphine A. Lacorre, Tracy T. Batchelor et al. « Edema Control by Cediranib, a Vascular Endothelial Growth Factor Receptor–Targeted Kinase Inhibitor, Prolongs Survival Despite Persistent Brain Tumor Growth in Mice ». Journal of Clinical Oncology 27, no 15 (20 mai 2009) : 2542–52. http://dx.doi.org/10.1200/jco.2008.19.9356.
Texte intégralRésumé :
Purpose Recent clinical trials of antivascular endothelial growth factor (VEGF) agents for glioblastoma showed promising progression-free and overall survival rates. However, available clinical imaging does not separate antitumor effects from antipermeability effects of these agents. Thus although anti-VEGF agents may decrease tumor contrast-enhancement, vascularity, and edema, the mechanisms leading to improved survival in patients remain incompletely understood. Our goal was to determine whether alleviation of edema by anti-VEGF agents alone could increase survival in mice. Methods We treated mice bearing three different orthotopic models of glioblastoma with a VEGF-targeted kinase inhibitor, cediranib. Using intravital microscopy, molecular techniques, and magnetic resonance imaging (MRI), we measured survival, tumor growth, edema, vascular morphology and function, cancer cell apoptosis and proliferation, and circulating angiogenic biomarkers. Results We show by intravital microscopy that cediranib significantly decreased tumor vessel permeability and diameter. Moreover, cediranib treatment induced normalization of perivascular cell coverage and thinning of the basement membrane, as mirrored by an increase in plasma collagen IV. These rapid changes in tumor vascular morphology and function led to edema alleviation—as measured by MRI and by dry/wet weight measurement of water content—but did not affect tumor growth. By immunohistochemistry, we found a transient decrease in macrophage infiltration and significant but minor changes in tumor cell proliferation and apoptosis. Systemically, cediranib increased plasma VEGF and placenta growth factor levels, and the number of circulating CXCR4+CD45+ cells. However, by controlling edema, cediranib significantly increased survival of mice in the face of persistent tumor growth. Conclusion Anti-VEGF agents may be able to improve survival of patients with glioblastoma, even without inhibiting tumor growth.
23
Frattolin, Jennifer, Daniel J. Watson, Willy V. Bonneuil, Matthew J. Russell, Francesca Fasanella Masci, Mikaila Bandara, Bindi S. Brook, Robert J. B. Nibbs et James E. Moore. « The Critical Importance of Spatial and Temporal Scales in Designing and Interpreting Immune Cell Migration Assays ». Cells 10, no 12 (7 décembre 2021) : 3439. http://dx.doi.org/10.3390/cells10123439.
Texte intégralRésumé :
Intravital microscopy and other direct-imaging techniques have allowed for a characterisation of leukocyte migration that has revolutionised the field of immunology, resulting in an unprecedented understanding of the mechanisms of immune response and adaptive immunity. However, there is an assumption within the field that modern imaging techniques permit imaging parameters where the resulting cell track accurately captures a cell’s motion. This notion is almost entirely untested, and the relationship between what could be observed at a given scale and the underlying cell behaviour is undefined. Insufficient spatial and temporal resolutions within migration assays can result in misrepresentation of important physiologic processes or cause subtle changes in critical cell behaviour to be missed. In this review, we contextualise how scale can affect the perceived migratory behaviour of cells, summarise the limited approaches to mitigate this effect, and establish the need for a widely implemented framework to account for scale and correct observations of cell motion. We then extend the concept of scale to new approaches that seek to bridge the current “black box” between single-cell behaviour and systemic response.
24
Zal, Tomasz, Grzegorz Chodaczek et M. Anna Zal. « Visualizing the physiological self-reactivity of epidermal γδ TCR (P3280) ». Journal of Immunology 190, no 1_Supplement (1 mai 2013) : 136.22. http://dx.doi.org/10.4049/jimmunol.190.supp.136.22.
Texte intégralRésumé :
Abstract Dendritic epidermal T cells (DETCs) remain activated in vivo at steady state through their monomorphic Vgamma5-Vdelta1 TCR, forming phosphotyrosine-rich aggregates located on projections, called PALPs (Chodaczek et al. 2012). This recent discovery suggests the existence of beneficial self-reactivity on the part of the evolutionarily-preserved γδ TCR. Located at barrier-forming squamous keratinocyte junctions, and remarkably long-lived, the PALPs display multiple hallmarks of true immunological synapses, including TCR clustering and CD3-zeta and ZAP70 tyrosine phosphorylation. Using two independent super-resolution microscopy techniques: the structured illumination microscopy (SIM) and stimulated emission depletion (STED), we show that PALPs consist of several tens of peripherally distributed, tyrosine-phosphorylated TCR microclusters. Individual microclusters are uniformly sized at 150-160 nm and are associated with distinct signaling intermediates, suggesting that they represent supra-molecular signaling assemblies of a defined composition. Intravital fluorescence recovery after photobleaching and high speed time-lapse imaging showed that small intracellular cargo granules trafficked bi-directionally within T cell protrusions between large stationary granules and the PALPs. These studies reveal the PALPs as dynamically active TCR-activatory immunological synapses, and suggest that this novel form of physiological TCR self-reactivity mediates homeostatic secretory functions.
25
Chawda, Chintan, Roisin McMorrow, Natasa Gaspar, Giorgia Zambito et Laura Mezzanotte. « Monitoring Immune Cell Function Through Optical Imaging : a Review Highlighting Transgenic Mouse Models ». Molecular Imaging and Biology 24, no 2 (4 novembre 2021) : 250–63. http://dx.doi.org/10.1007/s11307-021-01662-5.
Texte intégralRésumé :
Abstract Transgenic mouse models have facilitated research of human diseases and validation of therapeutic approaches. Inclusion of optical reporter genes (fluorescent or bioluminescent genes) in the targeting vectors used to develop such models makes in vivo imaging of cellular and molecular events possible, from the microscale to the macroscale. In particular, transgenic mouse models expressing optical reporter genes allowed accurately distinguishing immune cell types from trafficking in vivo using intravital microscopy or whole-body optical imaging. Besides lineage tracing and trafficking of different subsets of immune cells, the ability to monitor the function of immune cells is of pivotal importance for investigating the effects of immunotherapies against cancer. Here, we introduce the reader to state-of-the-art approaches to develop transgenics, optical imaging techniques, and several notable examples of transgenic mouse models developed for immunology research by critically highlighting the models that allow the following of immune cell function.
26
Wang, D. H., et R. L. Prewitt. « Longitudinal effect of captopril on aortic and arteriolar development in normotensive rats ». American Journal of Physiology-Heart and Circulatory Physiology 260, no 6 (1 juin 1991) : H1959—H1965. http://dx.doi.org/10.1152/ajpheart.1991.260.6.h1959.
Texte intégralRésumé :
Normotensive rats were chronically given 100 mg.kg-1.day-1 of captopril in their drinking water beginning 1 day before uninephrectomy. Mean blood pressure was significantly decreased 4 (17%) and 8 (18%) wk later in treated rats vs. age-matched controls. When histological techniques were used, a marked reduction of medial-intimal area of the abdominal aorta was found in treated rats at 4 (24%) and 8 (15%) wk without significant change in internal diameter. Cremaster arteriolar dimensions were measured by intravital microscopy after topical application of 10(-3) M adenosine. Structural diameter reductions occurred in large arterioles starting at 4 wk in treated rats and in small arterioles at 8 wk. Despite a significant increase in wall-to-lumen ratio of some large and small arterioles in treated rats, the wall cross-sectional area of these vessels was significantly decreased by captopril. Measured by stereological techniques, small arteriolar density decreased 17% at 4 wk and 13% at 8 wk in treated rats. Although decreased blood pressure may contribute to smaller aortic cross-sectional wall area, the effect of captopril was probably the major cause for smaller arteriolar lumens, reduced arteriolar cross-sectional wall areas, and arteriolar rarefaction.
27
Yankaskas, Christopher L., Kaustav Bera, Konstantin Stoletov, Selma A. Serra, Julia Carrillo-Garcia, Soontorn Tuntithavornwat, Panagiotis Mistriotis, John D. Lewis, Miguel A. Valverde et Konstantinos Konstantopoulos. « The fluid shear stress sensor TRPM7 regulates tumor cell intravasation ». Science Advances 7, no 28 (juillet 2021) : eabh3457. http://dx.doi.org/10.1126/sciadv.abh3457.
Texte intégralRésumé :
Tumor cell intravasation preferentially occurs in regions of low fluid shear because high shear is detrimental to tumor cells. Here, we describe a molecular mechanism by which cells avoid high shear during intravasation. The transition from migration to intravasation was modeled using a microfluidic device where cells migrating inside longitudinal tissue-like microchannels encounter an orthogonal channel in which fluid flow induces physiological shear stresses. This approach was complemented with intravital microscopy, patch-clamp, and signal transduction imaging techniques. Fluid shear–induced activation of the transient receptor potential melastatin 7 (TRPM7) channel promotes extracellular calcium influx, which then activates RhoA/myosin-II and calmodulin/IQGAP1/Cdc42 pathways to coordinate reversal of migration direction, thereby avoiding shear stress. Cells displaying higher shear sensitivity due to higher TRPM7 activity levels intravasate less efficiently and establish less invasive metastatic lesions. This study provides a mechanistic interpretation for the role of shear stress and its sensor, TRPM7, in tumor cell intravasation.
28
Bollinger, Alfred, Ulrich Hoffmann et Ulrich K. Franzeck. « Microvascular Changes in Arterial Occlusive Disease : Target for Pharmacotherapy ». Vascular Medicine 1, no 1 (février 1996) : 50–54. http://dx.doi.org/10.1177/1358863x9600100109.
Texte intégralRésumé :
The main techniques which have been used to study skin microcirculation in patients with peripheral arterial occlusive disease include intravital microscopy with and without the use of fluorescent dyes, laser Doppler fluxmetry and transcutaneous oximetry. In patients with severe ischaemia (rest pain or incipient gangrene) the number of perfused skin capillaries is reduced. Parallel to the decreased number of microvessels containing blood, transcutaneous oxygen tension is low or even approaches the zero level. The tendency to oedema formation is documented by increased leakage of intravenously injected sodium fluorescein at the capillary apex of foot skin (‘candlelight phenomenon’). Laser Doppler flux at rest may still be within the normal range even in advanced disease, since the sample volume of these instruments also contains non-nutritive shunt vessels. However, reactive hyperaemia after arterial occlusion is decreased and delayed in peripheral ischaemia. Whereas rhythmic low-frequency vasomotion is significantly enhanced in patients with intermittent claudication, vasoparalysis with no flux fluctuations prevails in patients with critical ischaemia.
29
Poudel, Nabin, Shuqiu Zheng, Colleen M. Schinderle, Naidi Sun, Song Hu et Mark D. Okusa. « Peritubular Capillary Oxygen Consumption in Sepsis-Induced AKI : Multi-Parametric Photoacoustic Microscopy ». Nephron 144, no 12 (2020) : 621–25. http://dx.doi.org/10.1159/000511167.
Texte intégralRésumé :
Understanding and measuring parameters responsible for the pathogenesis of sepsis-induced AKI (SI-AKI) is critical in developing therapies. Blood flow to the kidney is heterogeneous, partly due to the existence of dynamic networks of capillaries in various regions, responding differentially to oxygen demand in cortex versus medulla. High energy demand regions, especially the outer medulla, are susceptible to hypoxia and subject to damage during SI-AKI. Proximal tubule epithelial cells in the cortex and the outer medulla can also undergo metabolic reprogramming during SI-AKI to maintain basal physiological status and to avoid potential damage. Current data on the assessment of renal hemodynamics and oxygen metabolism during sepsis is limited. Preclinical and clinical studies show changes in renal hemodynamics associated with SI-AKI, and in clinical settings, interventions to manage renal hemodynamics seem to help improve disease outcomes in some cases. Lack of proper tools to assess temporospatial changes in peritubular blood flow and tissue oxygen metabolism is a barrier to our ability to understand microcirculatory dynamics and oxygen consumption and their role in the pathogenesis of SI-AKI. Current tools to assess renal oxygenation are limited in their usability as these cannot perform continuous simultaneous measurement of renal hemodynamics and oxygen metabolism. Multi-parametric photo-acoustic microscopy (PAM) is a new tool that can measure real-time changes in microhemodynamics and oxygen metabolism. Use of multi-parametric PAM in combination with advanced intravital imaging techniques has the potential to understand the contribution of microhemodynamic and tissue oxygenation alterations to SI-AKI.
30
Barkauskas, Deborah, Jay Myers, Youmna Othman et Alex Huang. « Imaging the initial cellular events in EAE. (123.26) ». Journal of Immunology 188, no 1_Supplement (1 mai 2012) : 123.26. http://dx.doi.org/10.4049/jimmunol.188.supp.123.26.
Texte intégralRésumé :
Abstract Limitations in current techniques to capture rare immune cell events have hindered the characterization of the initiation and progression of experimental autoimmune encephalomyelitis (EAE). With the cranial window and intravital two-photon microscopy techniques, we followed the initial dynamic and sequential cellular processes preceding EAE development. Disease progression was imaged daily in the first 12 days post EAE induction in either CX3CR1-GFP or CD11c-GFP transgenic mice containing adoptively transferred naïve ubiquitin-CFP myelin oligodendrocyte glycoprotein (MOG) specific T cells. Blood-brain barrier (BBB) permeability was assessed by i.v. injection of fluorescent dextran or quantum dots. We hypothesize that lymphocyte accumulation follows an initial transient BBB leak caused by pertussis toxin-initiated inflammation, with subsequent accumulation and activation of microglia and perivascular antigen presenting cells (APCs) facilitating the tissue-specific infiltration of MOG-specific T cells into the brain parenchyma via intra-luminal contact. Indeed, our sequential imaging experiments demonstrated transient leaks in BBB at the pia surface within the first 4 days post EAE induction, local APC accumulation from days 2 to 6, followed by T cell infiltration adjacent to local CNS vessel leak. Future work involves further defining the cellular and molecular regulation of CNS peri-vascular microenvironment responsible for cross-BBB attraction of MOG-specific cells.
31
Lavik, John-Paul, Vipul Shukla et R. Mark Wooten. « Intravital imaging of Borrelia burgdorferi and murine innate immune cells during early cutaneous infection. (37.42) ». Journal of Immunology 184, no 1_Supplement (1 avril 2010) : 37.42. http://dx.doi.org/10.4049/jimmunol.184.supp.37.42.
Texte intégralRésumé :
Abstract After tick transmission, the spirochete, Borrelia burgdorferi (Bb), remains at the skin inoculation site for up to 48 hours before spreading and causing Lyme disease. Bb surface agonists should elicit potent inflammation and clearance in skin. However, the ID50 is <50 Bb, indicating efficient immunoevasion and suggesting that traditional in vitro models are inadequate for accurately characterizing Bb pathogenesis (i.e. most models display efficient Bb clearance by phagocytes). Thus, we have devised a confocal microscopy method for visualizing infectious fluorescent Bb in situ and in real-time. Here, we inject Bb into ear skin of anesthetized mice and collect four-dimensional data regarding Bb motility during natural infection. This data is complemented by quantitative PCR and histological analyses of the temporal fall and rise of spirochete numbers in vivo. By 4h, the majority of Bb at the injection site are immobile, while Bb adjacent to the site are highly motile. Two movement types are seen: 1) a back and forth shift that may aid Bb in finding an optimal migration path and 2) a directed run that navigates dermal structures. Analysis indicates an average Bb velocity of ≥100 um per minute in skin, which is >10x faster than any immune cell velocities observed in our model. This suggests that Bb motility is a primary mechanism for host cell evasion and indicates our imaging techniques will allow true delineation of host-Bb interactions critical for Lyme disease development.
32
Myers, Jay T., Deborah S. Barkauskas et Alex Y. Huang. « Dynamic Imaging of Marrow-Resident Granulocytes Interacting with Human Mesenchymal Stem Cells upon Systemic Lipopolysaccharide Challenge ». Stem Cells International 2013 (2013) : 1–11. http://dx.doi.org/10.1155/2013/656839.
Texte intégralRésumé :
Human mesenchymal stem cells (hMSCs) have gained intense research interest due to their immune-modulatory, tissue differentiating, and homing properties to sites of inflammation. Despite evidence demonstrating the biodistribution of infused hMSCs in target organs using static fluorescence imaging or whole-body imaging techniques, surprisingly little is known about how hMSCs behave dynamically within host tissues on a single-cell levelin vivo. Here, we infused fluorescently labeled clinical-grade hMSCs into immune-competent mice in which neutrophils and monocytes express a second fluorescent marker under the lysozyme M (LysM) promoter. Using intravital two-photon microscopy (TPM), we were able for the first time to capture dynamic interactions between hMSCs and LysM+granulocytes in the calvarium bone marrow of recipient mice during systemic LPS challenge in real time. Interestingly, many of the infused hMSCs remained intact despite repeated cellular contacts with host neutrophils. However, we were able to observe the destruction and subsequent phagocytosis of some hMSCs by surrounding granulocytes. Thus, our imaging platform provides opportunities to gain insight into the biology and therapeutic mechanisms of hMSCsin vivoat a single-cell level within live hosts.
33
Shkodra, Blerina, Adrian T. Press, Antje Vollrath, Ivo Nischang, Stephanie Schubert, Stephanie Hoeppener, Dorothee Haas et al. « Formulation of Liver-Specific PLGA-DY-635 Nanoparticles Loaded with the Protein Kinase C Inhibitor Bisindolylmaleimide I ». Pharmaceutics 12, no 11 (18 novembre 2020) : 1110. http://dx.doi.org/10.3390/pharmaceutics12111110.
Texte intégralRésumé :
Bisindolylmaleimide I (BIM-I) is a competitive pan protein kinase C inhibitor with anti-inflammatory and anti-metastatic properties, suggested to treat inflammatory diseases and various cancer entities. However, despite its therapeutic potential, BIM-I has two major drawbacks, i.e., it has a poor water solubility, and it binds the human ether-à-go-go-related gene (hERG) ion channels, potentially causing deadly arrhythmias. In this case, a targeted delivery of BIM-I is imperative to minimize peripheral side effects. To circumvent these drawbacks BIM-I was encapsulated into nanoparticles prepared from poly(lactic-co-glycolic acid) (PLGA) functionalized by the near-infrared dye DY-635. DY-635 served as an active targeting moiety since it selectively binds the OATP1B1 and OATP1B3 transporters that are highly expressed in liver and cancer cells. PLGA-DY-635 (BIM-I) nanoparticles were produced by nanoprecipitation and characterized using dynamic light scattering, analytical ultracentrifugation, and cryogenic transmission electron microscopy. Particle sizes were found to be in the range of 20 to 70 nm, while a difference in sizes between the drug-loaded and unloaded particles was observed by all analytical techniques. In vitro studies demonstrated that PLGA-DY-635 (BIM-I) NPs prevent the PKC activation efficiently, proving the efficacy of the inhibitor after its encapsulation, and suggesting that BIM-I is released from the PLGA-NPs. Ultimately, our results present a feasible formulation strategy that improved the cytotoxicity profile of BIM-I and showed a high cellular uptake in the liver as demonstrated in vivo by intravital microscopy investigations.
34
Czabanka, Marcus, Lucia Lisa Petrilli, Susanne Elvers-Hornung, Karen Bieback, Beat Albert Imhof, Peter Vajkoczy et Maria Vinci. « Junctional Adhesion Molecule-C Mediates the Recruitment of Embryonic-Endothelial Progenitor Cells to the Perivascular Niche during Tumor Angiogenesis ». International Journal of Molecular Sciences 21, no 4 (11 février 2020) : 1209. http://dx.doi.org/10.3390/ijms21041209.
Texte intégralRésumé :
The homing of Endothelial Progenitor Cells (EPCs) to tumor angiogenic sites has been described as a multistep process, involving adhesion, migration, incorporation and sprouting, for which the underlying molecular and cellular mechanisms are yet to be fully defined. Here, we studied the expression of Junctional Adhesion Molecule-C (JAM-C) by EPCs and its role in EPC homing to tumor angiogenic vessels. For this, we used mouse embryonic-Endothelial Progenitor Cells (e-EPCs), intravital multi-fluorescence microscopy techniques and the dorsal skin-fold chamber model. JAM-C was found to be expressed by e-EPCs and endothelial cells. Blocking JAM-C did not affect adhesion of e-EPCs to endothelial monolayers in vitro but, interestingly, it did reduce their adhesion to tumor endothelium in vivo. The most striking effect of JAM-C blocking was on tube formation on matrigel in vitro and the incorporation and sprouting of e-EPCs to tumor endothelium in vivo. Our results demonstrate that JAM-C mediates e-EPC recruitment to tumor angiogenic sites, i.e., coordinated homing of EPCs to the perivascular niche, where they cluster and interact with tumor blood vessels. This suggests that JAM-C plays a critical role in the process of vascular assembly and may represent a potential therapeutic target to control tumor angiogenesis.
35
Fooksman, David, Michel Nussenzweig et Michael Dustin. « Myeloid cells regulate plasma cell responses in the lymph node (P1066) ». Journal of Immunology 190, no 1_Supplement (1 mai 2013) : 185.7. http://dx.doi.org/10.4049/jimmunol.190.supp.185.7.
Texte intégralRésumé :
Abstract Differentiation and survival of plasma cells requires the coordinated signaling from many different cell types, and these requirements vary depending on the tissue. In the lymph node, differentiating plasma cells migrate to the medullary cords where they can either arrest or exit the lymph node. Previously, we imaged and characterized plasmablast migration by intravital microscopy in the lymph node by transferring B cells expressing a YFP plasma cell reporter. Using recipient mice that express GFP in myelomonocytic cells, we observed that plasmablasts migrated along these cells in the medullary cords and arrested in contact with them. Since several cell types express GFP in this strain, we used a various ablation techniques to narrow down which subsets were engaged with plasmablasts and determine what role they perform. Ablation of one subset increased plasmablast numbers by 3 fold. This increase was largely due enhanced cell proliferation, but plasmablast apoptosis was also reduced. We have evidence to suggest that cytokine signaling and adhesion molecules play important roles. Localization of plasma cells in the lymph nodes may play an important function in controlling infection locally during early stages, while under autoimmune conditions, excessive plasma cell recruitment and survival can be detrimental. Regulating plasma cell survival and localization may provide ways to manipulating the immune response in both contexts.
36
Sekar, Padmapriya, Elizabeth Novak, A. Motaleb et Ronald Wooten. « Loss of chemotaxis gene ΔcheY3 in Borrelia burgdorferi leads to early immune clearance but does elicits a strong antibody response (MPF6P.647) ». Journal of Immunology 194, no 1_Supplement (1 mai 2015) : 202.5. http://dx.doi.org/10.4049/jimmunol.194.supp.202.5.
Texte intégralRésumé :
Abstract Borrelia burgdorferi (Bb) is a spirochetal bacterium that displays unique endoflagellar motility to efficiently disseminate through dense host tissues, and eventually persist within target tissues to cause Lyme disease. The importance of Bb motility/chemotaxis in dissemination/immune evasion cannot be correctly assessed in vitro, since the complexity of the host tissues cannot be accurately replicated. We assessed the importance of the chemotaxis-associated cheY3 gene on Bb dissemination and immune evasion within intact mouse tissues using our novel intravital microscopy techniques. CheY3-deficient (∆cheY3) Bb possessed similar cellular morphology and growth rates, but moves at lower velocities as wild-type (WT) Bb in murine skin tissues. Notably, GFP-ΔcheY3 were unable to reverse direction, whereas WT display primarily a sequential forward-and-reverse motility pattern. Within skin inoculation sites, ΔcheY3 were cleared by 72-96h post-infection and were not detected in distant tissues ≤day 60 post-infection. Interestingly, ∆cheY3-infected mice generate Bb-specific IgG levels similar to WT-infected animals at 14-28 days post-infection, though levels decrease by day 60. The antibody profile against ∆cheY3 Bb suggests that immunity is generated against many of the same Bb proteins as during WT infection. These findings suggest that cheY3 is essential for Bb persistence and that the attenuated ∆cheY3 Bb may serve as a vaccine to protect against Lyme disease.
37
Rizzoni, Damiano, Alessandro Mengozzi, Stefano Masi, Claudia Agabiti Rosei, Carolina De Ciuceis et Agostino Virdis. « New Noninvasive Methods to Evaluate Microvascular Structure and Function ». Hypertension 79, no 5 (mai 2022) : 874–86. http://dx.doi.org/10.1161/hypertensionaha.121.17954.
Texte intégralRésumé :
The structural and functional alterations of microvessels are detected because of physiological aging and in several cardiometabolic diseases, including hypertension, diabetes, and obesity. The small resistance arteries of these patients show an increase in the media or total wall thickness to internal lumen diameter ratio (MLR or WLR), often accompanied by endothelial dysfunction. For decades, micromyography has been considered as a gold standard method for evaluating microvascular structural alterations through the measurement of MLR or WLR of subcutaneous small vessels dissected from tissue biopsies. Micromyography is the most common and reliable method for assessing microcirculatory endothelial function ex vivo, while strain-gauge venous plethysmography is considered the reference technique for in vivo studies. Recently, several noninvasive methods have been proposed to extend the microvasculature evaluation to a broader range of patients and clinical settings. Scanning laser Doppler flowmetry and adaptive optics are increasingly used to estimate the WLR of retinal arterioles. Microvascular endothelial function may be evaluated in the retina by flicker light stimulus, in the finger by tonometric approaches, or in the cutaneous or sublingual tissues by laser Doppler flowmetry or intravital microscopy. The main limitation of these techniques is the lack of robust evidence on their prognostic value, which currently reduces their widespread use in daily clinical practice. Ongoing and future studies will overcome this issue, hopefully moving the noninvasive assessment of the microvascular function and structure from bench to bedside.
38
Summ, Oliver, Philip R. Holland, Simon Akerman et Peter J. Goadsby. « TRPV1 receptor blockade is ineffective in different in vivo models of migraine ». Cephalalgia 31, no 2 (1 juillet 2010) : 172–80. http://dx.doi.org/10.1177/0333102410375626.
Texte intégralRésumé :
Background: It has been proposed that TRPV1 receptors may play a role modulating trigeminal sensory processing. We used models of trigeminovascular nociceptive activation to study the involvement of TRPV1 receptors in the rat. Due to a possible role of TRPV1 receptors in cortical spreading depression (CSD), an experimental phenomenon sharing many features with migraine aura, we also utilized a model of mechanically induced CSD. Methods: Male Sprague Dawley rats ( N = 39) were anesthetized and cannulated for monitoring and drug administration to study the effects of the TRPV1 receptor antagonist A-993610 (8 mg kg−1 IV). Wide-dynamic-range neurons, responding to electrical stimulation of the middle meningeal artery (MMA)/dura mater were identified and recorded using electrophysiological techniques. Intravital microscopy was used to study neurogenic dural vasodilation (NDV) of the MMA comparing capsaicin and electrical stimulation, and the effect of A-993610 on mechanically induced CSD was examined. Results: Administration of A-993610 had no significant effect on trigeminal firing of A- or C-fibers elicited by electrical stimulation of the MMA. It also showed no effect on NDV whilst blocking vasodilation due to intravenous capsaicin injection. The mechanically induced CSD response could not be altered by A-993610 administration. Conclusions: Although there is evidence that TRPV1 receptors play an important role in sensory processing in general, the new data do not support a role in the treatment of acute migraine.
39
Akerman, Simon, Philip R. Holland et Jan Hoffmann. « Pearls and pitfalls in experimental in vivo models of migraine : Dural trigeminovascular nociception ». Cephalalgia 33, no 8 (13 mai 2013) : 577–92. http://dx.doi.org/10.1177/0333102412472071.
Texte intégralRésumé :
Background Migraine is a disorder of the brain and is thought to involve activation of the trigeminovascular system, which includes the peripheral afferent projection to the nociceptive specific dura mater, as well as the central afferent projection to the trigeminal nucleus caudalis. Stimulation of the blood vessels of the dura mater produces pain in patients that is referred to the head similar to headache. Headache mechanisms The likely reason for the pain is because the vascular structures of the dura mater, including the superior sagittal sinus and middle meningeal artery, are richly innervated by a plexus of largely unmyelinated sensory nerve fibers from the ophthalmic division of the trigeminal ganglion. Methodology Stimulation of these nociceptive specific nerve fibers is painful and produces neuronal activation in the trigeminal nucleus caudalis. Preclinical models of headache have taken advantage of this primarily nociceptive pathway, and various animal models use dural trigeminovascular nociception to assay aspects of head pain. These assays measure responses at the level of the dural vasculature and the central trigeminal nucleus caudalis as a correlate of trigeminovascular activation thought to be involved in headache. Summary This review will summarize the history of the development of models of dural trigeminovascular nociception, including intravital microscopy and laser Doppler flowmetry at the level of the vasculature, and electrophysiology and Fos techniques used to observe neuronal activation at the trigeminal nucleus caudalis. It will also describe some of pitfalls of these assays and developments for the future.
40
Kollmar, Otto, Marcus Corsten, Claudia Scheuer, Brigitte Vollmar, Martin K. Schilling et Michael D. Menger. « Portal branch ligation induces a hepatic arterial buffer response, microvascular remodeling, normoxygenation, and cell proliferation in portal blood-deprived liver tissue ». American Journal of Physiology-Gastrointestinal and Liver Physiology 292, no 6 (juin 2007) : G1534—G1542. http://dx.doi.org/10.1152/ajpgi.00503.2006.
Texte intégralRésumé :
Portal branch ligation (PBL) may prevent liver failure after extended hepatic resection. However, clinical studies indicate that tumors within the ligated lobe develop accelerated growth. Although it is well known that tumor growth depends on the host's microvascularization, there is no information about how PBL affects the hepatic microcirculation. Our aims were to determine hepatic artery response, liver microcirculation, tissue oxygenation, and cell proliferation after PBL. Therefore, we used intravital multifluorescence microscopy, laser-Doppler flowmetry, immunohistochemistry, and biochemical techniques to examine microcirculatory responses, microvascular remodeling, and cellular consequences after left lateral PBL in BALB/c mice. During the first 7 days, PBL induced a reduction of left hilar blood flow by ∼50%. This resulted in 80% sinusoidal perfusion failure, significant parenchymal hypoxia, and liver atrophy. After 14 days, however, left hilar blood flow was found to be restored. However, remodeling of the microvasculature included a rarefaction of the sinusoidal network, however, without substantial perfusion failure, compensated by a hepatic arterial buffer response and significant sinusoidal dilatation. This resulted in normalization of tissue oxygenation, indicating arterialization of the ligated lobe. Interestingly, late microvascular remodeling was associated with increased endothelial nitric oxide synthase expression, significant hepatocellular proliferation, and weight gain of the ligated lobe. Thus PBL induces only an initial microcirculatory failure with liver atrophy, followed by a hepatic arterial buffer response, microvascular remodeling, normoxygenation, and hepatocellular proliferation. This may explain the accelerated tumor progression occasionally observed in patients after PBL.
41
Torres Filho, Ivo P., Luciana N. Torres, Christi Salgado et Michael A. Dubick. « Plasma syndecan-1 and heparan sulfate correlate with microvascular glycocalyx degradation in hemorrhaged rats after different resuscitation fluids ». American Journal of Physiology-Heart and Circulatory Physiology 310, no 11 (1 juin 2016) : H1468—H1478. http://dx.doi.org/10.1152/ajpheart.00006.2016.
Texte intégralRésumé :
The endothelial glycocalyx plays an essential role in many physiological functions and is damaged after hemorrhage. Fluid resuscitation may further change the glycocalyx after an initial hemorrhage-induced degradation. Plasma levels of syndecan-1 and heparan sulfate have been used as indirect markers for glycocalyx degradation, but the extent to which these measures are representative of the events in the microcirculation is unknown. Using hemorrhage and a wide range of resuscitation fluids, we studied quantitatively the relationship between plasma biomarkers and changes in microvascular parameters, including glycocalyx thickness. Rats were bled 40% of total blood volume and resuscitated with seven different fluids (fresh whole blood, blood products, and crystalloids). Intravital microscopy was used to estimate glycocalyx thickness in >270 postcapillary venules from 58 cremaster preparations in 9 animal groups; other microvascular parameters were measured using noninvasive techniques. Systemic physiological parameters and blood chemistry were simultaneously collected. Changes in glycocalyx thickness were negatively correlated with changes in plasma levels of syndecan-1 ( r = −0.937) and heparan sulfate ( r = −0.864). Changes in microvascular permeability were positively correlated with changes in both plasma biomarkers ( r = 0.8, P < 0.05). Syndecan-1 and heparan sulfate were also positively correlated ( r = 0.7, P < 0.05). Except for diameter and permeability, changes in local microcirculatory parameters (red blood cell velocity, blood flow, and wall shear rate) did not correlate with plasma biomarkers or glycocalyx thickness changes. This work provides a quantitative framework supporting plasma syndecan-1 and heparan sulfate as valuable clinical biomarkers of glycocalyx shedding that may be useful in guiding resuscitation strategies following hemorrhage.
42
Tanaka, N., L. Mao, F. A. DeLano, E. M. Sentianin, K. R. Chien, G. W. Schmid-Schonbein et J. Ross. « Left ventricular volumes and function in the embryonic mouse heart ». American Journal of Physiology-Heart and Circulatory Physiology 273, no 3 (1 septembre 1997) : H1368—H1376. http://dx.doi.org/10.1152/ajpheart.1997.273.3.h1368.
Texte intégralRésumé :
This study describes miniaturized technology for the in vivo analysis of the volume and function of the embryonic mouse heart and the application of this technology to study the normal embryonic left ventricle (LV) at two stages of development. With the use of microsurgical techniques, embryos from embryonic day (ED) 10.5 (ED10.5) to ED16 were delivered individually from litters of normal dams, and cardiac visualization was achieved with the use of intravital microscopy by transillumination, with the umbilical circulation intact. At ED10.5-11, the heart could be imaged in color in the intact embryo, whereas at ED12.5 it was necessary to open the chest; at ED13.5-14.5, fluorescent imaging with the use of microinjection of fluorescein-conjugated albumin was necessary to visualize the LV chamber. At ED10.5-11, the LV end-diastolic volumes averaged 0.16 microliter (n = 14), and at ED13.5-14.5, they averaged 0.57 microliter (n = 16). At both ages there was a positive linear relationship between the LV end-diastolic volume and the stroke volume despite substantial variations in individual heart rates, reflecting the relative uniformity of the LV ejection fractions within each age group. The average of the individual ejection fractions was 27.4% at ED10.5-11 and 58.4% at ED13.5-14.5, the latter being within the normal range for the adult rodent heart. These methods will be useful for assessing in vivo cardiac function at ED10.5 and older murine embryos in litters of transgenic or gene-targeted mice when the mutation leads to later embryonic lethality.
43
Huang, Alex Yee-Chen, Jay T. Myers et Deborah Sim Barkauskas. « Dynamic real-time imaging of marrow-resident neutrophils interacting with human mesenchymal stem cells during systemic lipopolysaccharide challenge. » Journal of Clinical Oncology 31, no 15_suppl (20 mai 2013) : e22158-e22158. http://dx.doi.org/10.1200/jco.2013.31.15_suppl.e22158.
Texte intégralRésumé :
e22158 Background: Human mesenchymal stem cells (hMSCs) have gained intense interest due to their immune-modulatory, tissue differentiating and homing properties to sites of inflammation and tumor microenvironment, as evidenced by more than 200 ongoing clinical trials using hMSCs in a variety of clinical settings. Despite evidence demonstrating the bio-distribution of infused hMSCs in target organs using static fluorescence imaging or whole-body imaging techniques, there is controversy regarding how hMSCs exert their biological effects, and very little is known about how they behave dynamically within host tissues on a single-cell level in vivo. Methods: We infused fluorescently labeled clinical-grade hMSCs into immune-competent mice in which neutrophils and monocytes express a second fluorescent marker under the Lysozyme M (LysM) promoter. The recipient mice were then subjected to serial 4-D (xyzt) imaging of the bone marrow cavity with intravital two-photon microscopy (TPM) during acute systemic Lipopolysaccharide (LPS) challenges to observe changes in MSC and neutrophil migration behavior. Results: We were able, for the first time, to capture dynamic interactions between and migration pattern of hMSCs and LysM+granulocytes in the bone marrow of live mice during systemic LPS challenge. Contrary to some published reports, many of the infused hMSCs remained intact despite repeated cellular contacts with host neutrophils. However, we also observed the destruction and subsequent phagocytosis of some hMSCs by surrounding granulocytes. Conclusions: Our imaging platform provides opportunities to gain insight into the biology and therapeutic mechanisms of hMSCs in vivo at a single-cell level within live hosts.
44
Richardson, Troy E., Casey A. Kindig, Timothy I. Musch et David C. Poole. « Effects of chronic heart failure on skeletal muscle capillary hemodynamics at rest and during contractions ». Journal of Applied Physiology 95, no 3 (septembre 2003) : 1055–62. http://dx.doi.org/10.1152/japplphysiol.00308.2003.
Texte intégralRésumé :
Chronic heart failure (CHF) reduces muscle blood flow at rest and during exercise and impairs muscle function. Using intravital microscopy techniques, we tested the hypothesis that the speed and amplitude of the capillary red blood cell (RBC) velocity ( VRBC) and flux (FRBC) response to contractions would be reduced in CHF compared with control (C) spinotrapezius muscle. The proportion of capillaries supporting continuous RBC flow was less ( P < 0.05) in CHF (0.66 ± 0.04) compared with C (0.84 ± 0.01) muscle at rest and was not significantly altered with contractions. At rest, VRBC (C, 270 ± 62; CHF, 179 ± 14 μm/s) and FRBC (C, 22.4 ± 5.5 vs. CHF, 15.2 ± 1.2 RBCs/s) were reduced (both P < 0.05) in CHF vs. C muscle. Contractions significantly (both P < 0.05) elevated VRBC (C, 428 ± 47 vs. CHF, 222 ± 15 μm/s) and FRBC (C, 44.3 ± 5.5 vs. CHF, 24.0 ± 1.2 RBCs/s) in C and CHF muscle; however, both remained significantly lower in CHF than C. The time to 50% of the final response was slowed (both P < 0.05) in CHF compared with C for both VRBC (C, 8 ± 4; CHF, 56 ± 11 s) and FRBC (C, 11 ± 3; CHF, 65 ± 11 s). Capillary hematocrit increased with contractions in C and CHF muscle but was not different ( P > 0.05) between CHF and C. Thus CHF impairs diffusive and conductive O2 delivery across the rest-to-contractions transition in rat skeletal muscle, which may help explain the slowed O2 uptake on-kinetics manifested in CHF patients at exercise onset.
45
Poole, David C. « Edward F. Adolph Distinguished Lecture. Contemporary model of muscle microcirculation : gateway to function and dysfunction ». Journal of Applied Physiology 127, no 4 (1 octobre 2019) : 1012–33. http://dx.doi.org/10.1152/japplphysiol.00013.2019.
Texte intégralRésumé :
This review strikes at the very heart of how the microcirculation functions to facilitate blood-tissue oxygen, substrate, and metabolite fluxes in skeletal muscle. Contemporary evidence, marshalled from animals and humans using the latest techniques, challenges iconic perspectives that have changed little over the past century. Those perspectives include the following: the presence of contractile or collapsible capillaries in muscle, unitary control by precapillary sphincters, capillary recruitment at the onset of contractions, and the notion of capillary-to-mitochondrial diffusion distances as limiting O2 delivery. Today a wealth of physiological, morphological, and intravital microscopy evidence presents a completely different picture of microcirculatory control. Specifically, capillary red blood cell (RBC) and plasma flux is controlled primarily at the arteriolar level with most capillaries, in healthy muscle, supporting at least some flow at rest. In healthy skeletal muscle, this permits substrate access (whether carried in RBCs or plasma) to a prodigious total capillary surface area. Pathologies such as heart failure or diabetes decrease access to that exchange surface by reducing the proportion of flowing capillaries at rest and during exercise. Capillary morphology and function vary disparately among tissues. The contemporary model of capillary function explains how, following the onset of exercise, muscle O2 uptake kinetics can be extremely fast in health but slowed in heart failure and diabetes impairing contractile function and exercise tolerance. It is argued that adoption of this model is fundamental for understanding microvascular function and dysfunction and, as such, to the design and evaluation of effective therapeutic strategies to improve exercise tolerance and decrease morbidity and mortality in disease.
46
Holm, L., et M. A. Perry. « Role of blood flow in gastric acid secretion ». American Journal of Physiology-Gastrointestinal and Liver Physiology 254, no 3 (1 mars 1988) : G281—G293. http://dx.doi.org/10.1152/ajpgi.1988.254.3.g281.
Texte intégralRésumé :
The relationship between gastric acid secretion and blood flow has been investigated with a variety of different blood flow techniques including aminopyrine clearance, hydrogen gas clearance, intravital microscopy, laser-Doppler flowmetry, radioactive microspheres, and the elimination of inert gases. The most commonly used technique, aminopyrine clearance, predicts that increasing acid secretion is accompanied by a parallel increase in blood flow. However, the efficiency of clearance of aminopyrine is low in the nonsecreting stomach and increases as secretion rate increases. This precludes the use of aminopyrine clearance as a reliable measure of gastric mucosal blood flow at all but the highest steady-state level of acid secretion and casts doubt on the findings with this technique. Other methods for measuring blood flow indicate that there is no simple relationship between secretion and flow, with some studies finding that secretion and flow change in parallel and others finding that secretion varies quite independently of flow to the mucosa. One consistent finding is a strong correlation between stimulated acid secretion and gastric oxygen consumption. Both acid secretion and oxygen consumption fall if celiac blood flow is reduced below a critical value, which in the anesthetized dog stomach is approximately 30-40 ml.min-1.100 g-1. Driving blood flow above this value does not increase oxygen consumption and acid secretion, i.e., they reach a plateau. The shape of this relationship with its flow-dependent and flow-independent portions is used to explain the apparently contradictory findings in the literature regarding gastric acid secretion and blood flow.
47
Moseman, E. Ashley, Alexa F. Ciesinski et Dorian McGavern. « T cells Protect the Brain from a Nasal Virus Infection by Engaging Local Myeloid Cells that Cross-Present Antigen ». Journal of Immunology 200, no 1_Supplement (1 mai 2018) : 183.2. http://dx.doi.org/10.4049/jimmunol.200.supp.183.2.
Texte intégralRésumé :
Abstract Pathogens that gain entry into the CNS elicit a uniquely tailored response from the immune compartment by modulating cytolytic and inflammatory functions to confer viral clearance with minimal brain damage. Neurotropic viruses such as vesicular stomatitis virus (VSV) infect neurons in the olfactory epithelial barrier and pass via sensory axons directly into the brain. Within the olfactory bulb, VSV-infected neurons contact a variety of CNS neurons; however, the infection rarely invades the brain. While type I interferon responses are crucial for initial viral control, little is known about how the local adaptive immune response prevents fatal viral neuroinvasion. In this study, we sought insights into how cytotoxic lymphocytes (CTL) prevent the distal spread of infection from the olfactory bulb. Without T cells, virus containment is compromised and VSV traverses caudally to hindbrain regions. Utilizing intravital two-photon microscopy and other techniques, we characterized the mechanism by which T cell interactions within the olfactory bulb facilitate barrier protection. Interestingly, chimeric mice deficient in MHC class I on brain-resident cells, as well as microglia-depleted mice, showed reduced antiviral T cell calcium signaling upon engagement of target cells, suggesting that microglia can cross-present viral antigen and indirectly facilitate viral clearance from adjacent virally infected neurons. This study has revealed a novel mechanism of T cell-mediated viral control in neurons that involves engagement of resident myeloid cells that acquire antigen but are not infected by the virus. This in turn provides barrier protection against a virus that attempts to enter the CNS via the nasal route.
48
Pearson, Mark J., et Herbert H. Lipowsky. « Influence of erythrocyte aggregation on leukocyte margination in postcapillary venules of rat mesentery ». American Journal of Physiology-Heart and Circulatory Physiology 279, no 4 (1 octobre 2000) : H1460—H1471. http://dx.doi.org/10.1152/ajpheart.2000.279.4.h1460.
Texte intégralRésumé :
The role of erythrocyte (red blood cell; RBC) aggregation in affecting leukocyte (white blood cell; WBC) margination in postcapillary venules of the mesentery (rat) was explored by direct intravital microscopy. Optical techniques were refined and applied to relate the light-scattering properties of RBCs to obtain a quantitative index of aggregate size ( G), which, under idealized conditions, represents the number of RBCs per aggregate. WBC margination, defined as the radial migration of WBCs to the venular wall and their subsequent rolling along the endothelium, was measured as the percentage of the potentially maximal WBC volumetric flux within the microvessel lumen ( F WBC ∗). In normal blood, F WBC ∗ increased exponentially fourfold, and G increased from 1 to 1.15 as wall shear rates (γ˙) were reduced from a steady-state value of ∼600 to <100 s−1 by proximal occlusion with a blunt microprobe. Enhancement of aggregation by infusion (iv) of dextran 500 (428 kDa), to attain a systemic concentration of 3 g/100 ml, resulted in a four- and sevenfold increase in G and F WBC ∗, respectively, as γ˙was reduced below 100 s−1. Inhibition of RBC aggregation by infusion of dextran 40 (37.5 kDa) caused F WBC ∗ to fall to one-half of its steady-state level for γ˙ < 100 s−1. Thus it appears that the well-known increase of WBC margination with reductions in γ˙ is strongly dependent on the occurrence of RBC aggregation. Increasing the extent of RBC aggregation during reductions in γ˙ also increased the firm adhesion of WBCs to the endothelium because of an enhanced probability of contact between leukocytes and the postcapillary venular wall.
49
Bailey, Janet K., Casey A. Kindig, Brad J. Behnke, Timothy I. Musch, Geert W. Schmid-Schoenbein et David C. Poole. « Spinotrapezius muscle microcirculatory function : effects of surgical exteriorization ». American Journal of Physiology-Heart and Circulatory Physiology 279, no 6 (1 décembre 2000) : H3131—H3137. http://dx.doi.org/10.1152/ajpheart.2000.279.6.h3131.
Texte intégralRésumé :
Intravital microscopy facilitates insights into muscle microcirculatory structural and functional control, provided that surgical exteriorization does not impact vascular function. We utilized a novel combination of phosphorescence quenching, microvascular oxygen pressure (microvascular Po 2), and microsphere (blood flow) techniques to evaluate static and dynamic behavior within the exposed intact (I) and exteriorized (EX) rat spinotrapezius muscle. I and EX muscles were studied under control, metabolic blockade with 2,4-dinitrophenol (DNP), and electrically stimulated conditions with 1-Hz contractions, and across switches from 21 to 100% and 10% inspired O2. Surgical preparation did not alter spinotrapezius muscle blood flow in either I or EX muscle. DNP elevated muscle blood flow ∼120% ( P < 0.05) in both I and EX muscles ( P> 0.05 between I and EX). Contractions reduced microvascular Po 2 from 30.4 ± 4.3 to 21.8 ± 4.8 mmHg in I muscle and from 33.2 ± 3.0 to 25.9 ± 2.8 mmHg in EX muscles with no difference between I and EX. In each O2condition, there was no difference (each P > 0.05) in microvascular Po 2 between I and EX muscles (21% O2: I = 37 ± 1; EX = 36 ± 1; 100%: I = 62 ± 5; EX = 51 ± 9; 10%: I = 20 ± 1; EX = 17 ± 2 mmHg). Similarly, the dynamic behavior of microvascular Po 2 to altered inspired O2 was unaffected by the EX procedure [half-time ( t 1/2) to 100% O2: I = 23 ± 5; EX = 23 ± 4; t 1/2 to 10%: I = 14 ± 2; EX = 16 ± 2 s, both P > 0.05]. These results demonstrate that the spinotrapezius muscle can be EX without significant alteration of microvascular integrity and responsiveness under the conditions assessed.
50
Nolte, Dirk, Sven Pickelmann, Michael Lang, Peter Keipert et Konrad Messmer. « Compatibility of Different Colloid Plasma Expanders with Perflubron Emulsion ». Anesthesiology 93, no 5 (1 novembre 2000) : 1261–70. http://dx.doi.org/10.1097/00000542-200011000-00020.
Texte intégralRésumé :
Background Perfluorocarbon-based oxygen carriers have been proposed as an adjunct to autologous blood conservation techniques during elective surgery. To date, the effects of perfluorocarbon emulsions at the microcirculatory level have not been studied extensively. In this study the effects of perflubron emulsion on the microcirculation after acute normovolemic hemodilution (ANH) were investigated using different colloid plasma expanders. Methods The dorsal skin fold chamber model and intravital fluorescence microscopy were used for analysis of the microcirculation in the thin striated skin muscle of conscious hamsters (body weight, 40-60 g). Measurements of microvascular perfusion and leukocyte adhesion (n = 6 animals per experimental group) were made before and at 10, 30, and 60 min after ANH (to hematocrit 0.3) with either 6% hydroxyethyl starch 200/0.6 (HES), 3.5% gelatin, 5% human serum albumin (HSA), or 6% dextran 60 (DX-60) followed by intravenous injection of 3 ml/kg body weight of a 60% weight/volume perfluorocarbon emulsion based on perflubron (perfluorooctyl bromide) emulsified with egg yolk lecithin. Results Acute normovolemic hemodilution with HES, gelatin, or HSA followed by injection of perflubron emulsion elicited no alterations of local microvascular perfusion or leukocyte-endothelium interaction as assessed in arterioles and postcapillary venules. However, ANH with DX-60 followed by injection of perflubron emulsion led to a significant reduction of erythrocyte velocity in postcapillary venules and an increase in venular leukocyte sticking that was never observed with DX-60 alone. Conclusions Hydroxyethyl starch, gelatin, and HSA are compatible with perflubron emulsion in the setting of ANH. Only DX-60 appeared to be incompatible with perflubron emulsion, as evidenced by impairment of capillary perfusion.