No abstract

This study demonstrates that resting monocytes/macrophages can be loaded in vivo by a simple i.v. injection of fluorescent superparamagnetic iron oxide nanoparticles prior to injury and then tracked, in the same animal, in a model of ischaemia-reperfusion leading to myocardial infarct. Although previous studies of macrophages infiltration following MI have labelled the macrophages after injury, this study, for the first time, has pre-load the resting monocytes with fluorescent iron oxide nanoparticles.

The purpose of this study was to examine the anaesthetic requirement of intrathecal midazolam in a dose-response fashion in isoflurane-anaesthetized, tracheostomized rats, and to evaluate the apnoeic threshold after each intrathecal midazolam dose. Intrathecal midazolam,5,10,20, and 30 I~g, was administered

Using a flow-sensitive calibration, an accurate arterial input function can be measured from the blood MR signal and used in a realistic model to assess the RP. There was a good correlation between the MR-derived RP and the renal artery blood flow measured by the flow-meter. This experimental study validates absolute RP quantification by MRI and contrast media injection and justifies further clinical studies.

The aim of this study was to measure the myocardial area at risk in rat, using MRI and manganese injection during a coronary occlusion/reperfusion model at 1.5T. A sequential protocol with occlusion and MnCl 2 injection immediately followed by MRI was used with the assumption that MnCl 2 -induced contrast persistence is enough to accurately image the area at risk 90 min after occlusion. A total of 15 adult rats underwent a single 30-min episode of coronary occlusion followed by reperfusion. MnCl 2 was injected (25 mol/kg) at the beginning of the occlusion for 11 rats (group 1) and 6 h after reperfusion for four animals (group 2). A deficit of signal enhancement was observed in all rats. Hypoenhancement area in group 1 was correlated to the area at risk delineated by methylene blue (r ‫؍‬ 0.96, P < 0.0001) whereas in group 2 it was correlated to the infarct area given by triphenyltetrazolium chloride ( The area at risk is defined as the perfusion deficit zone following a coronary artery occlusion and it represents a major independent variable of the final myocardial infarct size (1). From experimental studies, we know that there exists a close linear relationship between the area at risk and infarct size (2,3). Therapies or experimental intervention can modify both the slope and the intercept of the infarct/area at risk relationship. Consequently, accurate measurements of the area at risk are important in the studies involving myocardial infarct. The measurement of area at risk is closely linked to perfusion imaging. In patients, radionuclide perfusion imaging, contrast echocardiography, and MRI have been used for the in vivo determination of the area at risk (4). The small size of the rat's heart has limited the use of these techniques for the in vivo measurement of the area at risk in rodent occlusion/reperfusion models of myocardial infarct. Perfusion assessment has been performed in rodents using echocardiography and contrast media injection (5). However, the complete assessment of the whole left ventricle has not been possible as the inferior region was inconstantly measured. Therefore, no robust method has yet been established to measure in vivo area at risk in rats. Postmortem analysis of the perfusion territory served by an occluded coronary artery remains the gold standard. Either dye or radiolabeled agents are injected (6 -8) after reocclusion of the coronary artery just before the sacrifice of the animal. A common difficulty of this procedure is related to the reocclusion procedure that needs to be performed at the exact same location as the first occlusion. To insure such consistency, the thread is left loosely around the coronary artery after the reperfusion. After a few days, scar formation precludes a reproducible reocclusion and limits the use of this technique for chronic studies. For long term studies in rats, an in vivo tool able to measure the area at risk at the time of the initial occlusion would be extremely beneficial. This is a valuable objective considering that rat models have an import...