Search results for "Perfusion"
showing 10 items of 714 documents
The blood perfusion mapping in the human skin by photoplethysmography imaging
2010
A CMOS camera-based imaging photoplethysmographic (PPGI) system is described to detect the blood pulsations in tissue. Attention of PPGI is drawn to the potential applications in visualized blood perfusion. Intensity variations of three wavelengths (620 nm, 520 nm and 432 nm) were detected and analyzed in each pixel of image. To obtain a twodimensional mapping of the dermal perfusion measurement, custom image-processing software has been developed. The high-resolution PPGI images were derived from human fingers (transmission mode) and face (reflection mode), evaluated at three wavelengths. The newly developed system can be usable in skin blood perfusion monitoring for clinical applications.
Modulation of tumor oxygenation
1998
There is a large body of evidence suggesting that deficiencies in the O2 supply of tumors exist due to restrictions (i) in the O2 delivery by perfusion and/or diffusion, and (ii) in the O2 transport capacity. Whereas the former are mostly based on inadequate and heterogeneous microcirculatory functions, the latter are predominantly due to tumor-associated anemia. Possible uses and limitations of measures are discussed which can increase the microvascular O2 content and thus may preferentially serve to enhance diffusion-limited O2 availability. In addition, means are described for improving and increasing the uniformity of microcirculation thus possibly enhancing perfusion-limited O2 deliver…
Vascularity, perfusion rate and local tissue oxygenation of tumors derived from ras-transformed fibroblasts.
2007
Tumors derived from ras-transformed rat fibroblasts were investigated in order to gain insight into possible interrelationships between oncogenic transformations and therapeutically relevant parameters of the metabolic micromilieu of solid tumors in vivo. Tumors grew in nude mice after injection of in vitro-passaged cells. Growth rates, early stages of angiogenesis, perfusion and tissue oxygenation were assessed. Compared with the parental cell line, both ras transformants grew very rapidly and exhibited an early onset of angiogenesis. Perfusion rates of one ras-transformed tumor line were similar to those of the parental tumors whereas reduced flow values were detected in tumors of the oth…
Diameter Control in the Arteriolar Tree by Changes in Post-Capillary Resistance
1997
Presently, the mechanisms underlying local adjustment of organ perfusion to the metabolic needs of the tissue are not well understood. Even though a large number of vasoactive substances is known to be released upon variations in tissue metabolism,24,28 the exact mechanisms of their action are unclear: Because diffusion is a slow and inefficient transport process for covering long distances, arterioles can only sense those changes in concentration and hence in release rate of these mediators with acceptable spatial and temporal resolution that originate from their immediate vicinity. On the other hand, perfusion needs to be regulated such that also the worst supplied tissue regions located …
The extracorporeal perfusion of the female pig detrusor as an experimental model for the study of bladder contractility.
2007
Aims The objective of the study was to establish an experimental model for the extracorporeal perfusion of the pig detrusor. In order to validate this model we examined some biochemical parameters and determined the effect of carbachol on the contractility of perfused female pig bladders. Methods Twenty-six pig bladders were perfused with Krebs–Ringer bicarbonate-glucose buffer for a period up to 5 hr with the aim to preserve a viable organ, which would be responsive to contraction-inducing agents. The intravesical pressure of the bladder as well as the intraarterial pressure of the vesical arteries were recorded before and after administration of carbachol. Results The perfusate pH, lactat…
In vitro effect of leptin on human cardiac contractility
2019
AbstractLeptin, a hormone produced by adipose tissue, has been linked to many regulatory pathways. Its role in the complex relationship between obesity and CVD is not yet clear. The aim of the present study was to evaluate whether leptin interferes directly with cardiac function regulation, altering its contractile force character, and hence contributing to different pathological processes. Muscle samples were obtained from human atrial myocardium. Each trial included two samples from the same patient. They were simultaneously electrically stimulated under sustained perfusion to perform isometric contractions. One sample was treated with a high concentration of human recombinant leptin (1 µ…
Intracoronary application of C1 esterase inhibitor improves cardiac function and reduces myocardial necrosis in an experimental model of ischemia and…
1997
Background Myocardial injury from ischemia can be aggravated by reperfusion of the jeopardized area. The precise underlying mechanisms have not been clearly defined, but proinflammatory events, including complement activation, leukocyte adhesion, and infiltration and release of diverse mediators, probably play important roles. The present study addresses the possibility of reducing reperfusion damage by the application of C1 esterase inhibitor (C1-INH). Methods and Results Cardioprotection by C1-INH 20 IU/kg IC was examined in a pig model with 60 minutes of coronary occlusion, followed by 120 minutes of reperfusion. C1-INH was administered during the first 5 minutes of coronary reperfusion…
Ischemic stroke increases heart vulnerability to ischemia-reperfusion and alters myocardial cardioprotective pathways
2018
Background and Purpose— For years, the relationship between cardiac and neurological ischemic events has been limited to overlapping pathophysiological mechanisms and common risk factors. However, acute stroke may induce dramatic changes in cardiovascular function. The aim of this study was to evaluate how prior cerebrovascular lesions affect myocardial function and signaling in vivo and ex vivo and how they influence cardiac vulnerability to ischemia-reperfusion injury. Methods— Cerebral embolization was performed in adult Wistar male rats through the injection of microspheres into the left or right internal carotid artery. Stroke lesions were evaluated by microsphere counting, tissue sta…
P863Morphometric analysis of the dynamic changes of the interstitium after reperfused myocardial infarction
2019
Abstract Background The interstitial space is mainly composed by cells, fibers and gels of polysaccharides, which act as a compression buffer against the stress placed on the extracellular matrix (ECM). After myocardial infarction (MI), heart has to withstand higher mechanical stress due to injured cardiomyocytes. ECM composition notably influences the mechanical properties of the myocardium and participates in left ventricular remodeling. Purpose To characterize the myocardial ECM changes from ischemia onset until late phases after coronary reperfusion in a swine model of reperfused MI. Methods MI was induced in swine by transient 90-min coronary occlusion using angioplasty balloons. One c…
C1-esterase inhibitor in ischemia and reperfusion.
2002
Summary Myocardial injury from ischemia can be aggravated by reperfusion of the jeopardized area. The precise underlying mechanisms have not been clearly defined, but proinflammatory events including complement activation play important roles. Cardioprotection by complement inhibition inter alia C1-esterase-inhibitor (C1-INH) was examined in several experimental models and under clinical conditions with ischemia and reperfusion. C1-INH reduced local anaphylatoxin release revealing the importance of the classical complement pathway. Inhibition of local complement activation was accompanied by improvement of myocardial function and perfusion of the previously ischemic myocardium. Leukocyte en…