1. Vorbereitung 1.1. Anästhesie der Ratten <ol><li> Legen Sie die Ratte in eine Kammer mit Isofluran (abhängig von der Größe der Kammer etwa 3 Minuten von 5%) vorausgefüllt, um die Ratte zu betäuben. </li><li> Einmal betäubt, entfernen Sie die Ratte und gewogen. </li><li> Legen Sie die Nase der Ratte in der Anästhesie-Maske (2-3% Isofluran in Sauerstoff 1 L / min) auf die Anästhesie zu halten. Während der Narkose mit Isofluran, die Herzfrequenz von 300-340 bpm Ratten (380-420 bpm in Mäuse) zu verringern. </li></ol> 1.2. Legen Sie eine Schwanzvene Kanüle <ol><li> Waschen Sie den Schwanz der Ratte mit warmem Wasser (38 ° C) und Seife, um die Blutgefäße zu leichter gesehen. </li><li> Kanülieren entweder Vene, die sich leicht auf der lateralen Seite des Schwanzes zu sehen. Mit einem 22-24 G iv Katheter, beginnen Versuche etwa 1/3 des Weges von der Spitze. </li><li> Wenn die anfänglichen Bemühungen erfolglos sind, mehr proximal wiederholen. </li><li> Nehmen Blut sample für die Analyse von Hämatokrit (notwendig extrazellulären Volumenanteil = ECV berechnen). </li><li> Sichern Sie die iv Katheter mit der Haut kleben und Klebeband. </li></ol> 1.3. Die Positionierung der Elektroden <ol><li> Reinigen Sie alle Straßenräuber mit Alkohol gesättigt Tupfer oder mit Wasser und Seife. </li><li> Vier Elektroden benötigt werden, eine für jeden Fuß. </li><li> Bringen Sie die Elektroden auf der Mitte der Fußsohle und sichern Sie sie mit Klebeband. </li><li> Twist oder Zopf die EKG-Kabel umeinander, um die Bildung von Maschen, die eine Störung des EKG-Signals würde zu minimieren. </li></ol> 2. Scannen 2.1. Positionieren des Tieres und Überwachung <ol><li> Legen Sie die Ratte in einer Rücken-oder Bauchlage auf die Bildröhre und positionieren das Herz in der Mitte der Spule. </li><li> Anordnen der Ratte, so daß die Nase in den Kegel, der Isofluran-Narkose liefert (2-3% Sauerstoff in 1 L / min) liegt. Die Ratte wird zum Atem erlaubtfrei in der gesamten Imaging-Verfahren. </li><li> Platzieren Sie den Sensor des Thermometers an der analen Öffnung und befestigen Sie es auf den Tisch mit Klebeband. </li><li> Die Körpertemperatur wird bei 38 ± 1 ° C durch eine Warmwasserheizung. Die Erwärmung Matte wird unter dem unteren Aspekt des Tieres, die außerhalb der Spule platziert erstreckt. Bitte beachten Sie die schematische Darstellung des MRI Versuchsaufbau (Abbildung 2) für weitere Details. </li><li> Schließen Sie die EKG-Elektroden, wenn das EKG-Signal ist stabil beginnen Bildgebung. </li></ol> 2.2. Scan-Protokoll / Imaging Parameter <ol><li> In dieser Studie wurde ein Philips Ingenia 3.0T klinischen MRT-System mit einer Magnetspule mit 70 mm Innendurchmesser verwendet wurde [MR Systemanforderungen sind eine kleine Bohrung (zB 16 cm) oder große Bohrung (menschliche Größe, zB 65 cm) mit dedizierten Kleintier Spule, EKG-Gating-Funktionen für Herzfrequenzen bis 500/min, Sauerstoffversorgung und eine Entnahme für Narkosegasen]. </li><li> Beginnen Sie mit einer Umfrage, um das Herz in der Mitte des MRI Sichtfeld lokalisieren. </li><li> Sobald die richtige Position ist, mit zwei Kammern und Vier-Kammer-cine MRI Ansichten weiterhin die Geometrie des Stapels von Kurzachsenschnitt bestimmen. </li><li> Für SALLI, Position Mitte Hohlraum Kurzachsenschnitt auf den Zwei-und Vier-Kammer-Bilder (PreSALLI). Eine Kombination von 4,000 ms Aufnahmedauer und 4000 msec Entspannzeitdauer ermöglicht ausreichende Wiederherstellung der Magnetisierung entlang der z-Achse und verhindert eine Überhitzung des Gradienten. Um funktionelle Analyse zu ermöglichen, sollten Phasen auf mindestens 12 gesetzt werden, mit zeitlichen Unterabtastung von Faktor 2 bis Akquisition beschleunigen. </li><li> Injizieren Sie die Gadolinium-basierte Kontrastmittel in den Dauerkatheter, ohne Verschieben der Ratte. Warten Sie fünf Minuten. </li><li> Planen SALLI als Mehrschicht kurzen Achse Stapel, bestehend aus mindestens 7 Scheiben (Schichtdicke 2,4 mm). Positionieren der Scheiben, so daß die am weitesten distal unterhalb der Herzspitze und ter oberste Ebene ist nur distal der Herzklappen. Versuchen Sie, um sicherzustellen, dass die kurzen Achsen senkrecht zur Scheidewand. Fast alle 30 Minuten (rund drei Sallis) injizieren eine weitere Dosis des Kontrastmittels. </li><li> Wenn Bildaufnahme beendet ist entfernen Sie die Ratte aus dem Scanner und lassen Sie es von der Narkose zu erholen. </li></ol> 3. Bildrekonstruktion Bildrekonstruktion kann durchgeführt werden entweder online über vordefinierte Parameter Wiederaufbau, oder offline mit einem dedizierten Bildrekonstruktion Tool: 3.1. Online Wiederaufbau <ol><li> Verschiedene Parameter können definiert werden, einschließlich: </li></ol><ul><li> Für T1-Mapping: Lage und Breite der Rekonstruktion Fenster innerhalb des Herzzyklus (zB von 50 bis 100 ms, um den systolischen T1 Karte bei Herzfrequenz 300/min zu erreichen) </li><li> Für IR-vorbereitet (LGE) Bilder: Lage und Breite der Inversion Zeit (TI) Fenster und die Anzahl der Bilder, um rekonstruierte wi seindünn, dass Fenster (zB TI 100-300 ms, 5 Bilder, bis 5 LGE Bilder mit TI 100-150-200-250-300 ms zu erzeugen). </li></ul> 3.2. Offline-Rekonstruktion <ol><li> Bei der Verwendung eines speziellen Software-Paket (GyroTools, Zürich, Schweiz) zur Bildrekonstruktion, extrahieren Sie die drei Sätze von Daten (Cine MR, Inversion-Recovery-und T1 Karten) in einer interaktiven Weise. </li><li> Stellen Sie die Definition von Endsystole oder Enddiastole für die T1 durch Auswahl der entsprechenden cine Bild. </li><li> Visualisieren T1 Karten als farbige Karten. Finden Sie exakte Werte, indem die Maus über einen Bereich von Interesse. Bilder können in verschiedenen Bildformaten zur weiteren Analyse (zB Berechnung der ECV von Pre-und Post-Kontrast T1 Werte Myokard und Blut-Pool) 12 gespeichert werden. </li></ol>

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	<li>Messroghli, D. R., Nordmeyer, S., Buehrer, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+animal+Look-Locker+inversion+recovery+(SALLI)+for+simultaneous+generation+of+cardiac+T1+maps+and+cine+and+inversion+recovery-prepared+images+at+high+heart+rates:+initial+experience.">Small animal Look-Locker inversion recovery (SALLI) for simultaneous generation of cardiac T1 maps and cine and inversion recovery-prepared images at high heart rates: initial experience.</a> Radiology. 261 (1), 258-2565 (2011).</li><li>Messroghli, D. R., Nordmeyer, S., Dietrich, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+diffuse+myocardial+fibrosis+in+rats+using+small-animal+Look-Locker+inversion+recovery+T1+mapping.">Assessment of diffuse myocardial fibrosis in rats using small-animal Look-Locker inversion recovery T1 mapping.</a> Circ. Cardiovasc. Imaging. 4 (6), 636-640 (2011).</li><li>Flett, A. S., Hayward, M. P., Ashworth, M. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Equilibrium+contrast+cardiovascular+magnetic+resonance+for+the+measurement+of+diffuse+myocardial+fibrosis:+preliminary+validation+in+humans.">Equilibrium contrast cardiovascular magnetic resonance for the measurement of diffuse myocardial fibrosis: preliminary validation in humans.</a> Circulation. 122 (2), 138-144 (2010).</li><li>Arheden, H., Saed, M., Higgins, C. N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+the+distribution+volume+of+gadopentetate+dimeglumine+at+echo-planar+MR+imaging+to+quantify+myocardial+infarction:+comparison+with+99mTc-DTPA+autoradiography+in+rats.">Measurement of the distribution volume of gadopentetate dimeglumine at echo-planar MR imaging to quantify myocardial infarction: comparison with 99mTc-DTPA autoradiography in rats.</a> Radiology. 211 (3), 698-708 (1999).</li><li>Messroghli, D. R., Walters, K., Plein, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myocardial+T1+mapping:+application+to+patients+with+acute+and+chronic+myocardial+infarction.">Myocardial T1 mapping: application to patients with acute and chronic myocardial infarction.</a> Magn. Reson. Med. 58 (1), 34-40 (2007).</li><li>O H-Ici, D., Ridgway, J., Kuehne, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiovascular+magnetic+resonance+of+myocardial+edema+using+a+short+inversion+time+inversion+recovery+(STIR)+black-blood+technique:+Diagnostic+accuracy+of+visual+and+semi-quantitative.">Cardiovascular magnetic resonance of myocardial edema using a short inversion time inversion recovery (STIR) black-blood technique: Diagnostic accuracy of visual and semi-quantitative.</a> 14 (1), (2012).</li><li>Sagar, S., Liu, P. P., Cooper, L. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myocarditis.">Myocarditis.</a> Lancet. 379, 738-747 (2012).</li><li>Skouri, H. N., Dec, G. W., Friedrich, M. G., Cooper, L. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+imaging+in+myocarditis.">Noninvasive imaging in myocarditis.</a> J. Am. Coll. Cardiol. , 2085-2093 (2006).</li><li>Zagrosek, A., Abdel-Aty, H., Boy&#233;, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+magnetic+resonance+monitors+reversible+and+irreversible+myocardial+injury+in+myocarditis.">Cardiac magnetic resonance monitors reversible and irreversible myocardial injury in myocarditis.</a> JACC Cardiovasc. Imaging. 2 (2), 131-138 (2009).</li><li>Friedrich, M. G., Sechtem, U., Schulz-Menger, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiovascular+magnetic+resonance+in+myocarditis:+a+JACC+White+Paper.">Cardiovascular magnetic resonance in myocarditis: a JACC White Paper.</a> J. Am. Coll. Cardiol. 54, 1475-1487 (2009).</li><li>Korkusuz, H., Esters, P., Naguib, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+myocarditis+in+a+rat+model:+late+gadolinium+enhancement+with+histopathological+correlation.">Acute myocarditis in a rat model: late gadolinium enhancement with histopathological correlation.</a> Eur. Radiol. 19 (11), 2672-2678 (2009).</li><li>Ugander, M., Oki, A. J., Hsu, L. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+volume+imaging+by+magnetic+resonance+imaging+provides+insights+into+overt+and+sub-clinical+myocardial+pathology.">Extracellular volume imaging by magnetic resonance imaging provides insights into overt and sub-clinical myocardial pathology.</a> Eur. Heart J. 33 (10), 1268-1278 (2012).</li><li>Gilson, W. D., Kraitchman, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+magnetic+resonance+imaging+in+small+rodents+using+clinical+1.5.">Cardiac magnetic resonance imaging in small rodents using clinical 1.5.</a> T and. 3 (1), 35-45 (2007).</li><li>Messroghli, D. R., Radjenovic, A., Kozerke, S., Higgins, D. M., Sivananthan, M. U., Ridgway, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modified+Look-Locker+inversion+recovery+(MOLLI)+for+high-resolution+T1+mapping+of+the+heart.">Modified Look-Locker inversion recovery (MOLLI) for high-resolution T1 mapping of the heart.</a> Magnetic resonance in medicine. 52 (1), 141-146 (2004).</li></ol>

Alle tierischen Verfahren wurden in Übereinstimmung mit den Richtlinien für die Pflege und Verwendung von Labortieren durchgeführt, und die von den lokalen Behörden Tierpflege. Keine Interessenskonflikte erklärt.

Hier präsentieren wir eine Methode, um Multi-Modalität (Cine MR, Inversion-Recovery-und T1 Karten) MR-Bilder in kleine Tiere zu erzeugen. Kleintier-Forschung spielt eine zunehmend wichtige Rolle in der Herz-Kreislauf-Krankheit Forschung und CMR ist ein leistungsstarkes Tool ermöglicht es uns, die Funktion, Struktur und Zusammensetzung Gewebe des Herzmuskels zu studieren. Allerdings hat Kleintier CMR eine Reihe von einzigartigen Herausforderungen aufgrund der hohen Herzfrequenzen und kleine Herzen Größe. Verbesserte...

Myokarditis ist eine der Hauptursachen der akuten Herzversagen, plötzlicher Tod und chronische Kardiomyopathie 7. CMR hat als Goldstandard-Technik zur Messung der Funktion und für in vivo Tissue-Analyse nachgewiesen. Neuartige bildgebende Verfahren und Verbesserungen in der Bildgebung konnte nicht nur zur Verbesserung der Diagnose der Myokarditis, sondern auch helfen, das Studium der Pathophysiologie und Geschwindigkeit Identifizierung therapeutischer Targets 8-10. Kleintier-Bildgebung ist ein wichtiges Werkzeug für die Untersuchung von Herz-Kreislauf-Erkrankungen. Techniken routinemäßig in der klinischen CMR verwendet werden, wie spät Gadolinium Enhancement (LGE) nicht einfach auf kleine Tier CMR wegen der Tiere hohe Herzfrequenzen übertragen werden; konnte aber bereits 11 gezeigt werden. Das kleine Tier Look-Locker Inversion-Recovery (SALLI) Ansatz erzeugt multimodalen Bilddaten setzt damit für die umfassende Bewertung sowohl Herzfunktion und Morphologie (Abb. 1 and 3). Hier zeigen wir im Detail, das Verfahren und die Einrichtung für Kleintier-Bildgebung mit einem typischen SALLI Protokoll. Insbesondere zeigen wir die Rekonstruktion und Analyse der T1 Bildgebung Datensätze.

<table border="1">
		<tbody>
		 <tr>
			<td>Name of Reagent/Material</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		 </tr>
		 <tr>
			<td>Adhesive Tape (Silkafix)</td>
			<td>Lohmann und Rauscher</td>
			<td>34327</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Gadopentetat-Dimeglumin (Magnevist)</td>
			<td>Bayer</td>
			<td>G-00012163</td>
			<td>2mmol/Kg</td>
		 </tr>
		 <tr>
			<td>Introcan Safety-W (G24)</td>
			<td>B. Braun</td>
			<td>4254503-01</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Red Dot, Neonatal Monitoring Electrode with Pre-Attached Lead Wire</td>
			<td>3M</td>
			<td>2269T</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Skin glue (Histoacryl)</td>
			<td>B. Braun</td>
			<td>1050052</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Scales (Typ 440)</td>
			<td>Kern</td>
			<td>95088</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Skin desinfection (Softasept N)</td>
			<td>B. Braun Petzold</td>
			<td>360250</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Thermometer </td>
			<td>LumaSense Technologies</td>
			<td>Luxtron 812</td>
			<td></td>
		 </tr>
		</tbody>
 </table>

assessment of cardiac function and myocardial morphology using small animal look-locker inversion recovery (salli) mri in rats

Kleintier-Magnetresonanz-Bildgebung ist ein wichtiges Instrument, um die Herzfunktion und Veränderungen im Herzmuskelgewebe zu studieren. Die hohen Herzfrequenzen von Kleintieren (200 bis 600 Schläge / min) haben die Rolle der Bildgebung CMR begrenzt. Kleintier-Look-Locker Inversion-Recovery (SALLI) ist ein T1-Mapping-Sequenz für Kleintiere, dieses Problem zu überwinden 1. T1 Karten liefern quantitative Informationen über Gewebeveränderungen und Kontrastmittel Kinetik. Es ist auch möglich, diffuse myokardialen Prozesse wie interstitielle Fibrose oder Ödem 1-6 zu erkennen. Weiterhin ist aus einem einzigen Satz von Bilddaten ist es möglich, die Herzfunktion und die myokardiale Narben durch Erzeugen cine und Inversion-Recovery-zubereitete Ende Gadolinium Anreicherungs-MR-Bildern 1 zu untersuchen. Das vorgestellte Video zeigt Schritt-für-Schritt die Verfahren zur Kleintier-Bildgebung CMR durchzuführen. Hier wird mit einer gesunden Sprague-Dawl präsentiertey Ratte, aber natürlich kann es zu verschiedenen kardialen kleinen Tiermodellen verlängert werden.

Hier zeigen wir die Erkenntnisse aus einer gesunden Sprague Dawley Ratte. Mit einer gut vorbereiteten Tier Setup wir zuvor beschrieben, ist es möglich, eine stabile EKG-Signal zu erhalten. Ähnlich wie bei menschlichen Herz-MRT-Protokolle, beginnen wir mit einer Umfrage, um das Herz zu finden. Wenn die Position der Ratte in der Spule korrekt ist, fahren wir mit einem Zwei-Kammer-Blick und einem Vier-Kammer-Blick auf die Geometrie für die SALLI Stapel erfassen. Die SALLI Technik erzeugt dre...

Watch this Scientific Journal Video about Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery SALLI MRI in Rats at JoVE.com

Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery SALLI MRI in Rats

Kontrastverstärkte kardiale Magnetresonanztomographie (CMR)-Bildgebung ermöglicht eine umfassende<em&gt; In vivo</em&gt; Beurteilung des Herzens in dem Tierversuch Herz-Kreislauferkrankungen. Hier haben wir ausführlich die Verfahren zur CMR Bildgebung, Rekonstruktion und Analyse mit Kleintier-Lock-Locker Inversion Recovery (SALLI) bei Ratten durchzuführen.

Beurteilung der Herzfunktion und Morphologie Myokardiale Mit Small Animal Look-Locker Inversion Recovery (SALLI) MRI in Ratten

Small animal magnetic resonance  imaging is an important tool to study cardiac function and changes in myocardial  tissue. The high heart rates of small ...

assessment-cardiac-function-myocardial-morphology-using-small-animal

Research

JoVE Journal

Medicine

Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery (SALLI) MRI in Rats

12.6K Aufrufe.  German Heart Institute Berlin. Kontrastverstärkte kardiale Magnetresonanztomographie (CMR)-Bildgebung ermöglicht eine umfassende In vivo Beurteilung des Herzens in dem Tierversuch Herz-Kreislauferkrankungen. Hier haben wir ausführlich die Verfahren zur CMR Bildgebung, Rekonstruktion und Analyse mit Kleintier-Lock-Locker Inversion Recovery (SALLI) bei Ratten durchzuführen.

Serie: Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery SALLI MRI in Rats

Assessment of Cardiac Function and Energetics in Isolated Mouse Hearts Using 31P NMR Spectroscopy

Bioengineered mouse models have become powerful research tools in determining causal relationships between molecular alterations and models of cardiovascular disease. Although molecular biology is necessary in identifying key changes in the signaling pathway, it is not a surrogate for functional significance. While physiology can provide answers to the question of function, combining physiology with biochemical assessment of metabolites in the intact, beating heart allows for a complete picture of cardiac function and energetics. For years, our laboratory has utilized isolated heart perfusions combined with nuclear magnetic resonance (NMR) spectroscopy to accomplish this task. Left ventricular function is assessed by Langendorff-mode isolated heart perfusions while cardiac energetics is measured by performing 31P magnetic resonance spectroscopy of the perfused hearts. With these techniques, indices of cardiac function in combination with levels of phosphocreatine and ATP can be measured simultaneously in beating hearts. Furthermore, these parameters can be monitored while physiologic or pathologic stressors are instituted. For example, ischemia/reperfusion or high workload challenge protocols can be adopted. The use of aortic banding or other models of cardiac pathology are apt as well. Regardless of the variants within the protocol, the functional and energetic significance of molecular modifications of transgenic mouse models can be adequately described, leading to new insights into the associated enzymatic and metabolic pathways. Therefore, 31P NMR spectroscopy in the isolated perfused heart is a valuable research technique in animal models of cardiovascular disease.

Assessment of Cardiac Function and Energetics in Isolated Mouse Hearts Using 31P NMR Spectroscopy

Langendorff-mode isolated heart perfusion, in conjunction with 31P NMR spectroscopy, combines the fields of biochemistry and physiology into one experiment. The protocol allows for the dynamic measurement of high energy phosphate content and turnover in the heart while concurrently monitoring physiologic function. When performed correctly, this is a valuable technique in the assessment of cardiac energetics.

Beurteilung der Herzfunktion und Energetik in isolierten Maus-Herzen mit 31 P-NMR-Spektroskopie

Bioengineered mouse models have become powerful research tools in determining causal relationships between molecular alterations and models of ...

Forschung

Medizin

Acute Myocardial Infarction in Rats

With heart failure leading the cause of death in the USA (Hunt), biomedical research is fundamental to advance medical treatments for cardiovascular diseases. Animal models that mimic human cardiac disease, such as myocardial infarction (MI) and ischemia-reperfusion (IR) that induces heart failure as well as pressure-overload (transverse aortic constriction) that induces cardiac hypertrophy and heart failure (Goldman and Tarnavski), are useful models to study cardiovascular disease. In particular, myocardial ischemia (MI) is a leading cause for cardiovascular morbidity and mortality despite controlling certain risk factors such as arteriosclerosis and treatments via surgical intervention (Thygesen). Furthermore, an acute loss of the myocardium following myocardial ischemia (MI) results in increased loading conditions that induces ventricular remodeling of the infarcted border zone and the remote non-infarcted myocardium. Myocyte apoptosis, necrosis and the resultant increased hemodynamic load activate multiple biochemical intracellular signaling that initiates LV dilatation, hypertrophy, ventricular shape distortion, and collagen scar formation. This pathological remodeling and failure to normalize the increased wall stresses results in progressive dilatation, recruitment of the border zone myocardium into the scar, and eventually deterioration in myocardial contractile function (i.e. heart failure). The progression of LV dysfunction and heart failure in rats is similar to that observed in patients who sustain a large myocardial infarction, survive and subsequently develops heart failure (Goldman). The acute myocardial infarction (AMI) model in rats has been used to mimic human cardiovascular disease; specifically used to study cardiac signaling mechanisms associated with heart failure as well as to assess the contribution of therapeutic strategies for the treatment of heart failure. The method described in this report is the rat model of acute myocardial infarction (AMI). This model is also referred to as an acute ischemic cardiomyopathy or ischemia followed by reperfusion (IR); which is induced by an acute 30-minute period of ischemia by ligation of the left anterior descending artery (LAD) followed by reperfusion of the tissue by releasing the LAD ligation (Vasilyev and McConnell). This protocol will focus on assessment of the infarct size and the area-at-risk (AAR) by Evan's blue dye and triphenyl tetrazolium chloride (TTC) following 4-hours of reperfusion; additional comments toward the evaluation of cardiac function and remodeling by modifying the duration of reperfusion, is also presented. Overall, this AMI rat animal model is useful for studying the consequence of a myocardial infarction on cardiac pathophysiological and physiological function.

The rat model of acute myocardial infarction (AMI) is useful to study the consequence of a MI on cardiac pathophysiological and physiological function.

Akuter Myokardinfarkt bei Ratten

With heart failure leading the cause of death in the USA (Hunt), biomedical research is fundamental to advance medical treatments for cardiovascular ...

MRI and PET in Mouse Models of Myocardial Infarction

Myocardial infarction is one of the leading causes of death in the Western world. The similarity of the mouse heart to the human heart has made it an ideal model for testing novel therapeutic strategies.
In vivo magnetic resonance imaging (MRI) gives excellent views of the heart noninvasively with clear anatomical detail, which can be used for accurate functional assessment. Contrast agents can provide basic measures of tissue viability but these are nonspecific. Positron emission tomography (PET) is a complementary technique that is highly specific for molecular imaging, but lacks the anatomical detail of MRI. Used together, these techniques offer a sensitive, specific and quantitative tool for the assessment of the heart in disease and recovery following treatment.
In this paper we explain how these methods are carried out in mouse models of acute myocardial infarction. The procedures described here were designed for the assessment of putative protective drug treatments. We used MRI to measure systolic function and infarct size with late gadolinium enhancement, and PET with fluorodeoxyglucose (FDG) to assess metabolic function in the infarcted region. The paper focuses on practical aspects such as slice planning, accurate gating, drug delivery, segmentation of images, and multimodal coregistration. The methods presented here achieve good repeatability and accuracy maintaining a high throughput.

We describe how to perform MRI and PET imaging of the mouse heart. The protocol is tailored to assess treatment efficacy in models of myocardial infarction and heart failure.

Myocardial infarction is one of the leading causes of death in the Western world. The similarity of the mouse heart to the human heart has made it an ...

Ascending Aortic Constriction in Rats for Creation of Pressure Overload Cardiac Hypertrophy Model

Ascending aortic constriction is the most common and successful surgical model for creating pressure overload induced cardiac hypertrophy and heart failure. Here, we describe a detailed surgical procedure for creating pressure overload and cardiac hypertrophy in rats by constriction of the ascending aorta using a small metallic clip. After anesthesia, the trachea is intubated by inserting a cannula through a half way incision made between two cartilage rings of trachea. Then a skin incision is made at the level of the second intercostal space on the left chest wall and muscle layers are cleared to locate the ascending portion of aorta. The ascending aorta is constricted to 50&#8211;60% of its original diameter by application of a small sized titanium clip. Following aortic constriction, the second and third ribs are approximated with prolene sutures. The tracheal cannula is removed once spontaneous breathing was re-established. The animal is allowed to recover on the heating pad by gradually lowering anesthesia. The intensity of pressure overload created by constriction of the ascending aorta is determined by recording the pressure gradient using trans-thoracic two dimensional Doppler-echocardiography. Overall this protocol is useful to study the remodeling events and contractile properties of the heart during the gradual onset and progression from compensated cardiac hypertrophy to heart failure stage.

We describe a stepwise procedure for creating pressure overload and left ventricular hypertrophy in Wistar rats by constriction of the ascending aorta using a small metallic clip. This model is extensively used for studying remodeling changes during cardiac hypertrophy and for identifying and evaluating strategies for regression of such changes.

Aufsteigend Aortakonstriktion bei Ratten zur Erstellung von Drucküberlast Herzhypertrophie Modell

Ascending aortic constriction is the most common and successful surgical model for creating pressure overload induced cardiac hypertrophy and heart ...

Assessment of Right Ventricular Structure and Function in Mouse Model of Pulmonary Artery Constriction by Transthoracic Echocardiography

Emerging clinical data support the notion that RV dysfunction is critical to the pathogenesis of cardiovascular disease and heart failure1-3. Moreover, the RV is significantly affected in pulmonary diseases such as pulmonary artery hypertension (PAH). In addition, the RV is remarkably sensitive to cardiac pathologies, including left ventricular (LV) dysfunction, valvular disease or RV infarction4. To understand the role of RV in the pathogenesis of cardiac diseases, a reliable and noninvasive method to access the RV structurally and functionally is essential.
A noninvasive trans-thoracic echocardiography (TTE) based methodology was established and validated for monitoring dynamic changes in RV structure and function in adult mice. To impose RV stress, we employed a surgical model of pulmonary artery constriction (PAC) and measured the RV response over a 7-day period using a high-frequency ultrasound microimaging system. Sham operated mice were used as controls. Images were acquired in lightly anesthetized mice at baseline (before surgery), day 0 (immediately post-surgery), day 3, and day 7 (post-surgery). Data was analyzed offline using software.
Several acoustic windows (B, M, and Color Doppler modes), which can be consistently obtained in mice, allowed for reliable and reproducible measurement of RV structure (including RV wall thickness, end-diastolic&#160;and end-systolic dimensions), and function (fractional area change, fractional shortening, PA peak velocity, and peak pressure gradient) in normal mice and following PAC.
Using this method, the pressure-gradient resulting from PAC was accurately measured in real-time using Color Doppler mode and was comparable to direct pressure measurements performed with a Millar high-fidelity microtip catheter. Taken together, these data demonstrate that RV measurements obtained from various complimentary views using echocardiography are reliable, reproducible and can provide insights regarding RV structure and function. This method will enable a better understanding of the role of RV cardiac dysfunction.

Right ventricle (RV) dysfunction is critical to the pathogenesis of cardiovascular disease, yet limited methodologies are available for its evaluation. Recent advances in ultrasound imaging provide a noninvasive and accurate option for longitudinal RV study. Herein, we detail a step-by-step echocardiographic method using a murine model of RV pressure overload.

Beurteilung der rechtsventrikulären Struktur und Funktion in Maus-Modell der Lungenarterie Verengung durch transthorakale Echokardiographie

Emerging clinical data support the notion that RV dysfunction is critical to the pathogenesis of cardiovascular disease and heart failure1-3. Moreover, ...

Echocardiographic and Histological Examination of Cardiac Morphology in the Mouse

An increasing number of genetically modified mouse models has become available in recent years. Moreover, the number of pharmacological studies performed in mice is high. Phenotypic characterization of these mouse models also requires the examination of cardiac function and morphology. Echocardiography and magnetic resonance imaging (MRI) are commonly used approaches to characterize cardiac function and morphology in mice. Echocardiographic and MRI equipment specialized for use in small rodents is&#160;expensive and requires a dedicated space. This protocol describes cardiac measurements in mice using a clinical echocardiographic system with a 15 MHz human vascular probe. Measurements are performed on anesthetized adult mice. At least three image sequences are recorded and analyzed for each animal in M-mode in the parasternal short-axis view. Afterwards, cardiac histological examination is performed, and cardiomyocyte diameters are determined on hematoxylin-eosin- or wheat germ agglutinin (WGA)-stained paraffin sections. Vessel density is determined morphometrically after Pecam-1 immunostaining. The protocol has been applied successfully to pharmacological studies and different genetic animal models under baseline conditions, as well as after experimental myocardial infarction by the permanent ligation of the left anterior descending coronary artery (LAD). In our experience, echocardiographic investigation is limited to anesthetized animals and is feasible in adult mice weighing at least 25 g.

Echocardiographic examination is frequently used in mice. Expensive high-resolution ultrasound devices have been developed for this purpose. This protocol describes an affordable echocardiographic procedure combined with histological morphometric analyses to determine cardiac morphology.

Echokardiographische und histologische Untersuchung der kardiale Morphologie in der Maus

An increasing number of genetically modified mouse models has become available in recent years. Moreover, the number of pharmacological studies performed ...

In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur

Endochondral fracture healing is a complex process involving the development of fibrous, cartilaginous, and osseous tissue in the fracture callus. The amount of the different tissues in the callus provides important information on the fracture healing progress. Available in vivo techniques to longitudinally monitor the callus tissue development in preclinical fracture-healing studies using small animals include digital radiography and &#181;CT imaging. However, both techniques are only able to distinguish between mineralized and non-mineralized tissue. Consequently, it is impossible to discriminate cartilage from fibrous tissue. In contrast, magnetic resonance imaging (MRI) visualizes anatomical structures based on their water content and might therefore be able to noninvasively identify soft tissue and cartilage in the fracture callus. Here, we report the use of an MRI-compatible external fixator for the mouse femur to allow MRI scans during bone regeneration in mice. The experiments demonstrated that the fixator and a custom-made mounting device allow repetitive MRI scans, thus enabling longitudinal analysis of fracture-callus tissue development.

In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur

The evaluation of tissue development in the fracture callus during endochondral bone healing is essential to monitor the healing process. Here, we report the use of a magnetic resonance imaging (MRI)-compatible external fixator for the mouse femur to allow MRI scans during bone regeneration in mice.

In Vivo Bewertung der Fraktur Kallus Entwicklung während der Knochenheilung bei Mäusen mit einem MRI-kompatiblen Osteosynthese Gerät für Maus Femur

Endochondral fracture healing is a complex process involving the development of fibrous, cartilaginous, and osseous tissue in the fracture callus. The ...

Normothermic Ex Situ Heart Perfusion in Working Mode: Assessment of Cardiac Function and Metabolism

The current standard method for organ preservation (cold storage, CS), exposes the heart to a period of cold ischemia that limits the safe preservation time and increases the risk of adverse post-transplantation outcomes. Moreover, the static nature of CS does not allow for organ evaluation or intervention during the preservation interval. Normothermic ex situ heart perfusion (ESHP) is a novel method for preservation of the donated heart that minimizes cold ischemia by providing oxygenated, nutrient-rich perfusate to the heart. ESHP has been shown to be non-inferior to CS in the preservation of standard-criteria donor hearts and has also facilitated the clinical transplantation of the hearts donated after the circulatory determination of death. Currently, the only available clinical ESHP device perfuses the heart in an unloaded, non-working state, limiting assessments of myocardial performance. Conversely, ESHP in working mode provides the opportunity for comprehensive evaluation of cardiac performance by assessment of functional and metabolic parameters under physiologic conditions. Moreover, earlier experimental studies have suggested that ESHP in working mode may result in improved functional preservation. Here, we describe the protocol for ex situ perfusion of the heart in a large mammal (porcine) model, which is reproducible for different animal models and heart sizes. The software program in this ESHP apparatus allows for real-time and automated control of the pump speed to maintain desired aortic and left atrial pressure and evaluates a variety of functional and electrophysiological parameters with minimal need for supervision/manipulation.

Normothermic ex situ heart perfusion (ESHP), preserves the heart in a beating, semi-physiologic state. When performed in a working mode, ESHP provides the opportunity to perform sophisticated assessments of donor heart function and organ viability. Here, we describe our method for myocardial performance evaluation during ESHP.

Normothermic Ex-Situ Herz Perfusion im Arbeitsmodus: Beurteilung der Herzfunktion und Stoffwechsel

The current standard method for organ preservation (cold storage, CS), exposes the heart to a period of cold ischemia that limits the safe preservation ...

Continuous Blood Sampling in Small Animal Positron Emission Tomography/Computed Tomography Enables the Measurement of the Arterial Input Function

For quantitative analysis and bio-kinetic modeling of positron emission tomography/computed tomography (PET/CT) data, the determination of the temporal blood time-activity concentration also known as arterial input function (AIF) is a key point, especially for the characterization of animal disease models and the introduction of newly developed radiotracers. The knowledge of radiotracer availability in the blood helps to interpret PET/CT-derived data of tissue activity. For this purpose, online blood sampling during the PET/CT imaging is advisable to measure the AIF. In contrast to manual blood sampling and image-derived approaches, continuous online blood sampling has several advantages. Besides the minimized blood loss, there is an improved resolution and a superior accuracy for the blood activity measurement. However, the major drawback of online blood sampling is the costly and time-consuming preparation to catheterize the femoral vessels of the animal. Here, we describe an easy and complete workflow for catheterization and continuous blood sampling during small animal PET/CT imaging and compared it to manual blood sampling and an image-derived approach. Using this highly-standardized workflow, the determination of the fluorodeoxyglucose ([18F]FDG) AIF is demonstrated. Further, this procedure can be applied to any radiotracer in combination with different animal models to create fundamental knowledge of tracer kinetic and model characteristics. This allows a more precise evaluation of the behavior of pharmaceuticals, both for diagnostic and therapeutic approaches in the preclinical research of oncological, neurodegenerative and myocardial diseases.

Here a protocol for continuous blood sampling during PET/CT imaging of rats to measure the arterial input function (AIF) is described. The catheterization, the calibration and setup of the system and the data analysis of the blood radioactivity are demonstrated. The generated data provide input parameters for subsequent bio-kinetic modeling.

Kontinuierliche Blutentnahme in der Kleintier-Positronen-Emissionstomographie/Computertomographie ermöglicht die Messung der arteriellen Eingabefunktion

For quantitative analysis and bio-kinetic modeling of positron emission tomography/computed tomography (PET/CT) data, the determination of the temporal ...

Echocardiographic Assessment of Cardiac Anatomy and Function in Adult Rats

The use of experimental animal models has become crucial in cardiovascular science. Most studies using rodent models are focused on two-dimensional imaging to study the cardiac anatomy of the left ventricle and M-mode echo to assess its dimensions. However, this could limit a comprehensive study. Herein, we describe a protocol that allows an assessment of the heart chamber size, left ventricular function (systolic and diastolic) and valvular function. A conventional medical ultrasound machine was used in this protocol and different echo views were obtained through left parasternal, apical and suprasternal windows. In the left parasternal window, the long and short axis were acquired to analyze left chamber dimensions, right ventricle and pulmonary artery dimensions, and mitral, pulmonary and aortic valve function. The apical window allows the measurement of heart chamber dimensions and evaluation of systolic and diastolic parameters. It also allows Doppler assessment with detection and quantification of heart valve disturbances (regurgitation or stenosis). Different segments and walls of the left ventricle are visualized throughout all views. Finally, the ascending aorta, aortic arch, and descending aorta can be imaged through the suprasternal window. A combination of ultrasound imaging, Doppler flow and tissue Doppler assessment have been obtained to study cardiac morphology and function. This represents an important contribution to improve the assessment of cardiac function in adult rats with impact for research using these animal models.

A non-invasive protocol for transthoracic echocardiography assessment of cardiac anatomy and function for adult rats is presented in the current study. The heart valves, all four cardiac chambers and the ascending aorta, aortic arch and descending aorta are studied in detail.

Echokardiographische Beurteilung der Herzanatomie und Funktion bei erwachsenen Ratten

The use of experimental animal models has become crucial in cardiovascular science. Most studies using rodent models are focused on two-dimensional ...