Gefördert durch American Heart Association und March of Dimes.

Dieses Protokoll wurde von der Institutional Animal Care und Verwenden Ausschuss an der Stanford University und hält sich an die National Institutes of Health Richtlinien für die Verwendung von Versuchstieren verabschiedet. Neonatal Rat HIE-Modell <ol><li> Post-Natal-Tag (PND) 7 Sprague-Dawley Ratten Welpen (Charles River Laboratories, Inc., Wilmington, MA) sind voll mit Isofluran (Aerrane, Baxter, Deerfield, IL, 3-4% für Induktions-und 1-2% für Wartung). </li><li> Durch einen kleinen Schnitt in den Hals gemacht (Extra Thin Iris Scissors # 14088-10, Fine Science Tools Inc, Foster City, CA) auf der linken Arteria carotis communis (CCA) aussetzen. </li><li> Der CCA ist mit 5-0 Seidenfaden (5-0 Seide, Ethicon, Somer, NJ) ligiert. </li><li> Der Schnitt wird mit Cyanacrylat-Klebstoff (Elmers Products Inc, Columbus, OH) geschlossen. Der Schnitt wird mit Klebeband abgedeckt und Anästhesie wird gestoppt. Die Welpen sind, um ihre Mutter zurück und lässt 1-2 Stunden erholen. </li><li> Welpen sind dann in einer hypoxischen Kammer, die 8% Sauerstoff mit 92% Stickstoff für 100 Minuten bei 37 ° C. ausgewogenen enthält platziert 8% oxygen/92% Stickstoff (Airgas, Sacramento, CA) fließen über einen Schlauch in die Maus Käfig mit einer Kunststoffabdeckung ausgestattet. Der Deckel unternommen wird, um den Käfig fit und hat zwei Löcher von 2 cm im Durchmesser, ermöglicht eine davon mit dem Rohr verbunden, um die 8% Sauerstoff Gastank und anderen erhalten das Gas flowout. Die Kammer ist in ein Wasserbad gestellt und ist bis vor gewärmt zu bedienen und ein Thermometer im Inneren der muss 37 ° C vor Beginn der Hypoxie zu registrieren. </li><li> Am Ende der 100 Minuten von Hypoxie, sind die Welpen wieder zu ihren Damm für die Verwertung zurückgegeben. </li><li> 24 Stunden nach dem Ende der Hypoxie, sind Welpen durch tiefe Narkose mit Isofluran getötet. Hirngewebe wird mit kaltem physiologischer Kochsalzlösung perfundiert, gefolgt von einer Lösung aus kaltem 1% TTC in Phosphat-gepufferter Kochsalzlösung, pH 7,4 (Sigma Chemical Co, St Louis, MO). TTC muss immer vor Licht geschützt werden. </li><li> Brains entfernt und gekühlt 1-2 Minuten auf dem Eis, und vier koronalen Abschnitte 3 mm auseinander (Ebenen 1-4) geschnitten werden, beginnend rostral auf der Ebene der opticchiasm und Infundibulum, entsprechend der Bregma 1,8 ~ 2,0 mm Höhe der adulten Maus Gehirn. </li><li> Hirnschnitten werden in TTC-Lösung getaucht und bei 37 ° C für 8 Minuten, gefolgt von Fixierung in 4% Paraformaldehyd / PBS über Nacht. Da TTC lichtempfindlich ist, halten Scheiben fern von Licht in dieser Zeit. </li><li> Der TTC gefärbten Schnitten werden gescannt und digitalisiert. Mit Bild-J (NIH, Bethesda, MD), die folgenden sind für jede Ebene gemessen: Bereich des Infarktes (ungefärbten Bereich), im Bereich der ipsilateralen Hemisphäre und im Bereich der kontralateralen Hemisphäre. Der prozentuale Infarktareal pro Scheibe wie folgt berechnet: (Bereich der Infarkt / Bereich der ipsilateralen Hemisphäre) oder A 1, A 2, A 3 und A 4. Der prozentuale Volumen des Infarkts ist als die Summe (A 1 + A 2 + A 3 + A 4) * 3mm berechnet. Bereiche der kortikalen oder striatalen Verletzungen können auch separat in einer ähnlichen Weise quantifiziert werden. </li></ol> Repräsentative Ergebnisse <img src="/files/ftp_upload/old/955_2008_9_2_2/955_Fig-01.png" alt="Abbildung 1" width="660" height="190" /> Abbildung 1. Vertreter HIE koronalen Ebenen 1-4 gefärbt mit TTC. TTC gefärbten koronalen Abschnitte demonstrieren Bereich der Infarkt (in weiß).

<ol>
	<li>Rice, J. E., Vannucci, R. C., Brierley, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+immaturity+on+hypoxic-ischemic+brain+damage+in+the+rat.">The influence of immaturity on hypoxic-ischemic brain damage in the rat.</a> Annals of neurology. 9 (2), 131-141 (1981).</li><li>Vannucci, R. C., Vannucci, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Perinatal+Hypoxic-Ischemic+Brain+Damage:+Evolution+of+an+Animal+Model.">Perinatal Hypoxic-Ischemic Brain Damage: Evolution of an Animal Model.</a> Dev Neurosci. 27 (2-4), 81-86 (2005).</li><li>Bona, E., Hagberg, H., Loberg, E. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protective+effects+of+moderate+hypothermia+after+neonatal+hypoxia-ischemia:+short-+and+long-term+outcome.">Protective effects of moderate hypothermia after neonatal hypoxia-ischemia: short- and long-term outcome.</a> Pediatric research. 43 (6), 738-738 (1998).</li><li>Trescher, W. H., Ishiwa, S., Johnston, M. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+hypothermia+and+hyperthermia+on+attentional+and+spatial+learning+deficits+following+neonatal+hypoxia-ischemic+insult+in+rats.">Effects of hypothermia and hyperthermia on attentional and spatial learning deficits following neonatal hypoxia-ischemic insult in rats.</a> Behavioural brain research. 151 (1-2), 209-209 (2004).</li><li>Mishima, K., Ikeda, T., Yoshikawa, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Brief+post-hypoxic-ischemic+hypothermia+markedly+delays+neonatal+brain+injury.">Brief post-hypoxic-ischemic hypothermia markedly delays neonatal brain injury.</a> Brain development. 19 (5), 326-326 (1997).</li><li>Young, R. S., Olenginski, T. P., Yagel, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+graded+hypothermia+on+hypoxic-ischemic+brain+damage:+a+neuropathologic+study+in+the+neonatal+rat.">The effect of graded hypothermia on hypoxic-ischemic brain damage: a neuropathologic study in the neonatal rat.</a> Stroke; a journal of cerebral circulation. 14 (6), 929-929 (1983).</li><li>Bederson, J. B., Pitts, L. H., Germano, S. 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=Evaluation+of+2,3,5-triphenyltetrazolium+chloride+as+a+stain+for+detection+and+quantification+of+experimental+cerebral+infarction+in+rats.">Evaluation of 2,3,5-triphenyltetrazolium chloride as a stain for detection and quantification of experimental cerebral infarction in rats.</a> Stroke; a journal of cerebral circulation. 17 (6), 1304-1304 (1986).</li><li>Cai, J., Kang, Z., Liu, W. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+therapy+reduces+apoptosis+in+neonatal+hypoxia-ischemia+rat+model.">Hydrogen therapy reduces apoptosis in neonatal hypoxia-ischemia rat model.</a> Neuroscience letters. 441 (2), 167-167 (2008).</li><li>Grow, J., Barks, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathogenesis+of+hypoxic-ischemic+cerebral+injury+in+the+term+infant:+current+concepts.">Pathogenesis of hypoxic-ischemic cerebral injury in the term infant: current concepts.</a> Clinics in perinatology. 29 (4), 585-585 (2002).</li><li>Aden, U., Halldner, L., Lagercrantz , H., 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=Aggravated+brain+damage+after+hypoxic+ischemia+in+immature+adenosine+A2A+knockout+mice.">Aggravated brain damage after hypoxic ischemia in immature adenosine A2A knockout mice.</a> Stroke; a journal of cerebral circulation. 34 (3), 739-739 (2003).</li></ol>

Das Nagetier postnatale HIE-Modell ist ein etabliertes Modell, rekapituliert zerebralen Hypoxie in der perinatalen Periode bei Neugeborenen auftreten. Umfangreiche histologische und immunhistochemische Charakterisierung Studien haben gezeigt, dass die 7 Tage alte Nagetier der analogen Gehirn Reife zu einer dritten Trimester menschlichen Fötus 7 Modell hat. Das Nagetier HIE-Modell wurde sehr informativ für das Verständnis der Mechanismen der Hirnschädigung von perinatalen Hypoxie 2, wo Eingriffe wie Hypothermie wurd...

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<td>Sprague-Dawley Rat Pups</td>
<td>Animal</td>
<td>Charles River Laboratories</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
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<td>Isoflurane</td>
<td>Surgery</td>
<td>Aerrane,Baxter</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
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<td>8% Oxygen/ 92% Nitrogen Gas</td>
<td>Surgery</td>
<td>Airgas</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
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<td>2,3,5-triphenyl tetrazolium chloride </td>
<td>Reagent</td>
<td>Sigma-Aldrich</td>
<td>T8877</td>
<td>&nbsp;</td>
<tr>
<td>Phosphate buffered saline (PBS) pH 7.4 </td>
<td>Reagent</td>
<td>Gibco/Invitrogen</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
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<td>Paraformaldehyde</td>
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the hypoxic ischemic encephalopathy model of perinatal ischemia

Hypoxisch-ischämischen Enzephalopathie (HIE) ist die Folge der systemischen Asphyxie auftreten bei der Geburt. Fünfundzwanzig Prozent der Neugeborenen mit HIE entwickeln schweren und dauerhaften neuropsychologischen Spätfolgen, darunter geistige Retardierung, Zerebralparese und Epilepsie. Die Ergebnisse der HIE sind verheerend und permanent, so dass es kritisch zu identifizieren und zu entwickeln, therapeutische Strategien zu Hirnverletzungen bei Neugeborenen reduzieren mit HIE. Zu diesem Zweck hat die neugeborenen Rattenmodell für hypoxisch-ischämischen Hirn-Trauma wurde entwickelt, um diese conditio humana Modell. Die HIE-Modell wurde erstmals von Vannucci et al 1 validiert und ist seitdem intensiv genutzt, um Mechanismen der Hirnschädigung durch perinatale Hypoxie-Ischämie 2 zu identifizieren und zu testen, mögliche therapeutische Interventionen 3,4. Die HIE-Modell ist ein zweistufiger Prozess und umfasst die Ligation der linken Arteria carotis communis durch die Exposition gegenüber einer hypoxischen Umgebung gefolgt. Zerebralen Blutflusses (CBF) in der Hemisphäre ipsilateral zur ligiert Halsschlagader nicht wegen der Sicherheit des Blutflusses über den Kreis der Willis Rückgang, allerdings mit geringeren Sauerstoff-Partialdruck nimmt die CBF in der ipsilateralen Hemisphäre deutlich und führt zu einseitigen ischämischen Schädigung . Die Verwendung von 2,3,5-Triphenyltetrazoliumchlorid (TTC) zu färben und zu identifizieren ischämische Hirngewebe wurde ursprünglich für die Erwachsenen-Modelle von Nagetier zerebraler Ischämie 5 entwickelt, und wird verwendet, um das Ausmaß der zerebralen infarctin zu frühen Zeitpunkten bewerten bis zu 72 Stunden nach dem ischämischen Ereignis 6. In diesem Video zeigen wir die hypoxisch-ischämischen Schädigung Modell in postnatalen Rattenhirn und der Auswertung der Infarktgröße mittels TTC-Färbung.

Watch this Scientific Journal Video about The Hypoxic Ischemic Encephalopathy Model of Perinatal Ischemia at JoVE.com

The Hypoxic Ischemic Encephalopathy Model of Perinatal Ischemia

Die postnatale Rattenmodell für hypoxisch-ischämischen Hirn-Trauma ist ein gut etabliertes Modell der menschlichen Neugeborenen hypoxisch ischämischen Enzephalopathie (HIE). In diesem Artikel beschreiben wir das Modell der HIE in postnatalen Rattenjungen.

Die hypoxische ischämischen Enzephalopathie Model of Perinatal Ischämie

Hypoxic-Ischemic Encephalopathy (HIE) is the consequence of systemic asphyxia occurring at birth. Twenty five percent of neonates with HIE develop severe ...

the-hypoxic-ischemic-encephalopathy-model-of-perinatal-ischemia

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Biology

35.6K Aufrufe.  Stanford University School of Medicine. Die postnatale Rattenmodell für hypoxisch-ischämischen Hirn-Trauma ist ein gut etabliertes Modell der menschlichen Neugeborenen hypoxisch ischämischen Enzephalopathie (HIE). In diesem Artikel beschreiben wir das Modell der HIE in postnatalen Rattenjungen.

Serie: The Hypoxic Ischemic Encephalopathy Model of Perinatal Ischemia

Computer-Generated Animal Model Stimuli

Communication between animals is diverse and complex. Animals may communicate using auditory, seismic, chemosensory, electrical, or visual signals. In particular, understanding the constraints on visual signal design for communication has been of great interest. Traditional methods for investigating animal interactions have used basic observational techniques, staged encounters, or physical manipulation of morphology. Less intrusive methods have tried to simulate conspecifics using crude playback tools, such as mirrors, still images, or models. As technology has become more advanced, video playback has emerged as another tool in which to examine visual communication (Rosenthal, 2000). However, to move one step further, the application of computer-animation now allows researchers to specifically isolate critical components necessary to elicit social responses from conspecifics, and manipulate these features to control interactions. Here, I provide detail on how to create an animation using the Jacky dragon as a model, but this process may be adaptable for other species. In building the animation, I elected to use Lightwave  3D to alter object morphology, add texture, install bones, and provide comparable weight shading that prevents exaggerated movement. The animation is then matched to select motor patterns to replicate critical movement features. Finally, the sequence must rendered into an individual clip for presentation. Although there are other adaptable techniques, this particular method had been demonstrated to be effective in eliciting both conspicuous and social responses in staged interactions.

Computer-generated stimuli using the Jacky dragon as a model.

Computer-Generated-Tiermodell Stimuli

Communication between animals is diverse and complex. Animals may communicate using auditory, seismic, chemosensory, electrical, or visual signals. In ...

Forschung

Biologie

Embryonic Stem Cell-Derived Endothelial Cells for Treatment of Hindlimb Ischemia

Peripheral arterial disease (PAD) results from narrowing of the peripheral arteries that supply oxygenated blood and nutrients to the legs and feet, This pathology causes symptoms such as intermittent claudication (pain with walking), painful ischemic ulcerations, or even limb-threatening gangrene. It is generally believed that the vascular endothelium, a monolayer of endothelial cells that invests the luminal surface of all blood and lymphatic vessels, plays a dominant role in vascular homeostasis and vascular regeneration. As a result, stem cell-based regeneration of the endothelium may be a promising approach for treating PAD.In this video, we demonstrate the transplantation of embryonic stem cell (ESC)-derived endothelial cells for treatment of unilateral hindimb ischemia as a model of PAD, followed by non-invasive tracking of cell homing and survival by bioluminescence imaging. The specific materials and procedures for cell delivery and imaging will be described. This protocol follows another publication in describing the induction of hindlimb ischemia by Niiyama et al.1

The surgical procedure for delivery of embryonic stem cell-derived endothelial cells to the ischemic hindlimb is demonstrated, with non-invasive tracking by bioluminescence imaging.

Embryonale Stammzellen gewonnenen Endothelzellen zur Behandlung von Ischämie Hinterlauf

Peripheral arterial disease (PAD) results from narrowing of the peripheral arteries that supply oxygenated blood and nutrients to the legs and feet, This ...

Murine Model of Hindlimb Ischemia 

In the United States, peripheral arterial disease (PAD) affects about 10 million individuals, and is also prevalent worldwide. Medical therapies for symptomatic relief are limited. Surgical or endovascular interventions are useful for some individuals, but long-term results are often disappointing. As a result, there is a need for developing new therapies to treat PAD. The murine hindlimb ischemia preparation is a model of PAD, and is useful for testing new therapies. When compared to other models of tissue ischemia such as coronary or cerebral artery ligation, femoral artery ligation provides for a simpler model of ischemic tissue. Other advantages of this model are the ease of access to the femoral artery and low mortality rate. 
In this video, we demonstrate the methodology for the murine model of unilateral hindimb ischemia. The specific materials and procedures for creating and evaluating the model will be described, including the assessment of limb perfusion by laser Doppler imaging. This protocol can also be utilized for the transplantation and non-invasive tracking of cells, which is demonstrated by Huang et al.1.

Murine Model of Hindlimb Ischemia

The surgical procedure for induction of unilateral hindlimb ischemia is demonstrated, with confirmation of ischemia by laser Doppler perfusion imaging.

Mausmodell der hinteren Gliedmaßen Ischämie

In the United States, peripheral arterial disease (PAD) affects about 10 million individuals, and is also prevalent worldwide.  Medical therapies for ...

Slide Preparation Method to Preserve Three-dimensional Chromatin Architecture of Testicular Germ Cells

During testicular germ cell differentiation, the structure of nuclear chromatin dynamically changes. The following describes a method designed to preserve the three-dimensional chromatin arrangement of testicular germ cells found in mice; this method has been termed as the three-dimensional (3D) slide method. In this method, testicular tubules are directly treated with a permeabilization step that removes cytoplasmic material, followed by a fixation step that fixes nuclear materials. Tubules are then dissociated, the cell suspension is cytospun, and cells adhere to slides. This method improves sensitivity towards detection of subnuclear structures and is applicable for immunofluorescence, DNA, and RNA fluorescence in situ hybridization (FISH) and the combination of these detection methods. As an example of a possible application of the 3D slide method, a Cot-1 RNA FISH is shown to detect nascent RNAs. The 3D slide method will facilitate the detailed examination of spatial relationships between chromatin structure, DNA, and RNA during testicular germ cell differentiation.

The material here describes a method developed to preserve the three-dimensional chromatin structure of testicular germ cells. This has been termed the three-dimensional (3D) slide method. This method improves sensitivity for detection of subnuclear structures and is applicable for immunofluorescence, DNA, and RNA fluorescence in situ hybridization (FISH).

Folienvorbereitungsmethode zur Erhaltung der dreidimensionalen Chromatinarchitektur von Hodenkeimzellen

During testicular germ cell differentiation, the structure of nuclear chromatin dynamically changes. The following describes a method designed to preserve ...

An Anoxia-starvation Model for Ischemia/Reperfusion in C. elegans

Protocols for anoxia/starvation in the genetic model organism C. elegans simulate ischemia/reperfusion. Worms are separated from bacterial food and placed under anoxia for 20 hr&#160;(simulated ischemia), and subsequently moved to a normal atmosphere with food (simulated reperfusion). This experimental paradigm results in increased death and neuronal damage, and techniques are presented to assess organism viability, alterations to the morphology of touch neuron processes, as well as touch sensitivity, which represents the behavioral output of neuronal function. Finally, a method for constructing hypoxic incubators using common kitchen storage containers is described. The addition of a mass flow control unit allows for alterations to be made to the gas mixture in the custom incubators, and a circulating water bath allows for both temperature control and makes it easy to identify leaks. This method provides a low cost alternative to commercially available units.

An Anoxia-starvation Model for Ischemia/Reperfusion in C. elegans

A protocol is described that uses anoxia/starvation in C. elegans to model ischemia/reperfusion. Functional outcomes include increased mortality, visible abnormalities in GFP-labeled neuronal processes, and impaired behavioral responses that require neuronal function.

Ein Anoxia-Hunger-Modell für Ischämie / Reperfusion in<em&gt; C. elegans</em

Protocols for anoxia/starvation in the genetic model organism C. elegans simulate ischemia/reperfusion. Worms are separated from bacterial food and placed ...

Assessment of Myofilament Ca2+ Sensitivity Underlying Cardiac Excitation-contraction Coupling

Heart failure and cardiac arrhythmias are the leading causes of mortality and morbidity worldwide. However, the mechanism of pathogenesis and myocardial malfunction in the diseased heart remains to be fully clarified. Recent compelling evidence demonstrates that changes in the myofilament Ca2+ sensitivity affect intracellular Ca2+ homeostasis and ion channel activities in cardiac myocytes, the essential mechanisms responsible for the cardiac action potential and contraction in healthy and diseased hearts. Indeed, activities of ion channels and transporters underlying cardiac action potentials (e.g., Na+, Ca2+ and K+ channels and the Na+-Ca2+ exchanger) and intracellular Ca2+ handling proteins (e.g., ryanodine receptors and Ca2+-ATPase in sarcoplasmic reticulum (SERCA2a) or phospholamban and its phosphorylation) are conventionally measured to evaluate the fundamental mechanisms of cardiac excitation-contraction (E-C) coupling. Both electrical activities in the membrane and intracellular Ca2+ changes are the trigger signals of E-C coupling, whereas myofilament is the functional unit of contraction and relaxation, and myofilament Ca2+ sensitivity is imperative in the implementation of myofibril performance. Nevertheless, few studies incorporate myofilament Ca2+ sensitivity into the functional analysis of the myocardium unless it is the focus of the study. Here, we describe a protocol that measures sarcomere shortening/re-lengthening and the intracellular Ca2+ level using Fura-2 AM (ratiometric detection) and evaluate the changes of myofilament Ca2+ sensitivity in cardiac myocytes from rat hearts. The main aim is to emphasize that myofilament Ca2+ sensitivity should be taken into consideration in E-C coupling for mechanistic analysis. Comprehensive investigation of ion channels, ion transporters, intracellular Ca2+ handling, and myofilament Ca2+ sensitivity that underlie myocyte contractility in healthy and diseased hearts will provide valuable information for designing more effective strategies of translational and therapeutic value.

Assessment of Myofilament Ca2+ Sensitivity Underlying Cardiac Excitation-contraction Coupling

This paper describes a protocol that assesses the changes of myofilament Ca2+ sensitivity during contraction in isolated cardiac myocytes from rat heart. Together with cardiac electrophysiology, systolic/diastolic cytosol Ca2+ levels and contraction/relaxation, this measurement is imperative in underpinning the mechanisms mediating cardiac excitation-contraction coupling in healthy and diseased hearts.

Beurteilung der myofilament Ca<sup&gt; 2+</sup&gt; Empfindlichkeit Basiswert Cardiac elektromechanischen Kopplung

Heart failure and cardiac arrhythmias are the leading causes of mortality and morbidity worldwide. However, the mechanism of pathogenesis and myocardial ...

Co-immunoprecipitation Assay Using Endogenous Nuclear Proteins from Cells Cultured Under Hypoxic Conditions

Low oxygen levels (hypoxia) trigger a variety of adaptive responses with the Hypoxia-inducible factor 1 (HIF-1) complex acting as a master regulator. HIF-1 consists of a heterodimeric oxygen-regulated &#945; subunit (HIF-1&#945;) and constitutively expressed &#946; subunit (HIF-1&#946;) also known as aryl hydrocarbon receptor nuclear translocator (ARNT), regulating genes involved in diverse processes including angiogenesis, erythropoiesis and glycolysis. The identification of HIF-1 interacting proteins is key to the understanding of the hypoxia signaling pathway. Besides the regulation of HIF-1&#945; stability, hypoxia also triggers the nuclear translocation of many transcription factors including HIF-1&#945; and ARNT. Notably, most of the current methods used to study such protein-protein interactions (PPIs) are based on systems where protein levels are artificially increased through protein overexpression. Protein overexpression often leads to non-physiological results arising from temporal and spatial artifacts. Here we describe a modified co-immunoprecipitation protocol following hypoxia treatment using endogenous nuclear proteins, and as a proof of concept, to show the interaction between HIF-1&#945; and ARNT. In this protocol, the hypoxic cells were harvested under hypoxic conditions and the Dulbecco's Phosphate-Buffered Saline (DPBS) wash buffer was also pre-equilibrated to hypoxic conditions before usage to mitigate protein degradation or protein complex dissociation during reoxygenation. In addition, the nuclear fractions were subsequently extracted to concentrate and stabilize endogenous nuclear proteins and avoid possible spurious results often seen during protein overexpression. This protocol can be used to demonstrate endogenous and native interactions between transcription factors and transcriptional co-regulators under hypoxic conditions.

Here we describe a co-immunoprecipitation protocol to study protein-protein interactions between endogenous nuclear proteins under hypoxic conditions. This method is suitable for demonstration of the interactions between transcription factors and transcriptional co-regulators at hypoxia.

Co-Immunopräzipitation Assay mit endogenen nuklearen Proteinen aus Zellen kultiviert unter hypoxischen Bedingungen

Low oxygen levels (hypoxia) trigger a variety of adaptive responses with the Hypoxia-inducible factor 1 (HIF-1) complex acting as a master regulator. ...

Mass Spectrometry Analysis to Identify Ubiquitylation of EYFP-tagged CENP-A (EYFP-CENP-A)

Studying the structure and the dynamics of kinetochores and centromeres is important in understanding chromosomal instability (CIN) and cancer progression. How the chromosomal location and function of a centromere (i.e., centromere identity) are determined and participate in accurate chromosome segregation is a fundamental question. CENP-A is proposed to be the non-DNA indicator (epigenetic mark) of centromere identity, and CENP-A ubiquitylation is required for CENP-A deposition at the centromere, inherited through dimerization between cell division, and indispensable to cell viability.
Here we describe mass spectrometry analysis to identify ubiquitylation of EYFP-CENP-A K124R mutant suggesting that ubiquitylation at a different lysine is induced because of the EYFP tagging in the CENP-A K124R mutant protein. Lysine 306 (K306) ubiquitylation in EYFP-CENP-A K124R was successfully identified, which corresponds to lysine 56 (K56) in CENP-A through mass spectrometry analysis. A caveat is discussed in the use of GFP/EYFP or the tagging of high molecular weight protein as a tool to analyze the function of a protein. Current technical limit is also discussed for the detection of ubiquitylated bands, identification of site-specific ubiquitylation(s), and visualization of ubiquitylation in living cells or a specific single cell during the whole cell cycle.
The method of mass spectrometry analysis presented here can be applied to human CENP-A protein with different tags and other centromere-kinetochore proteins. These combinatory methods consisting of several assays/analyses could be recommended for researchers who are interested in identifying functional roles of ubiquitylation.

Mass Spectrometry Analysis to Identify Ubiquitylation of EYFP-tagged CENP-A EYFP-CENP-A

CENP-A ubiquitylation is an important requirement for CENP-A deposition at the centromere, inherited through dimerization between cell division, and indispensable to cell viability. Here we describe mass spectrometry analysis to identify ubiquitylation of EYFP-tagged CENP-A (EYFP-CENP-A) protein.

Massenspektrometrieanalyse zur Identifizierung der Ubiquitylierung von EIFP-A mit EYFP-Tags (EYFP-CENP-A)

Studying the structure and the dynamics of kinetochores and centromeres is important in understanding chromosomal instability (CIN) and cancer ...

A Modified Surgical Model of Hind Limb Ischemia in ApoE-/- Mice using a Miniature Incision

The purpose of this study is to introduce and evaluate a modified surgical approach to induce acute ischemia in mice that can be implemented in most animal laboratories.&#160;Contrary to the conventional approach for double ligation of the femoral artery (DLFA), a smaller incision on the right inguinal region was made to expose the proximal femoral artery (FA) to perform DLFA. Then, using a 7-0 suture, the incision was dragged to the knee region to expose the distal FA. Magnetic resonance imaging (MRI) on bilateral hind limbs was used to detect FA occlusion after the surgery. At 0, 1, 3, 5, and 7 days after the surgery, functional recovery of the hind limbs was visually assessed and graded using the Tarlov scale. Histologic evaluation was performed after euthanizing the animals 7 days after DLFA. The procedures were successfully performed on the right leg in ten ApoE-/- mice, and no mice died during subsequent observation. The incision sizes in all 10 mice were less than 5 mm (4.2 &#177; 0.63 mm). MRI results showed that FA blood flow in the ischemic side was clearly blocked. The Tarlov scale results demonstrated that hind limb function significantly decreased after the procedure and slowly recovered over the following 7 days. Histologic evaluation showed a significant inflammatory response on the ischemic side and reduced microvascular density in the ischemic hind limb. In conclusion, this study introduces a modified technique using a miniature incision to perform hind limb ischemia (HLI) using DLFA.

A Modified Surgical Model of Hind Limb Ischemia in ApoE-/- Mice using a Miniature Incision

This article demonstrates an efficient surgical approach to establish acute ischemia in mice with a small incision. This approach can be applied by most research groups without any laboratory upgrades.

A Modified Surgical Model of Hind Limb Ischemia in ApoE-/- Mäuse mit einem Miniaturschnitt

The purpose of this study is to introduce and evaluate a modified surgical approach to induce acute ischemia in mice that can be implemented in most ...

Development of a Cell Co-Culture Model to Mimic Cardiac Ischemia/Reperfusion In Vitro

Ischemic heart disease is the leading cause of death and disability worldwide. Reperfusion causes additional injury beyond ischemia. Endothelial cells (ECs) can protect cardiomyocytes (CMs) from reperfusion injury through cell-cell interactions. Co-cultures can help investigate the role of cell-cell interactions. A mixed co-culture is the simplest approach but is limited as isolated treatments and downstream analyses of single cell types are not feasible. To investigate whether ECs can dose-dependently attenuate CM cell damage and whether this protection can be further optimized by varying the contact distance between the two cell lines, we used Mouse Primary Coronary Artery Endothelial Cells and Adult Mouse Cardiomyocytes to test three types of cell culture inserts which varied in their inter-cell layer distance at 0.5, 1.0, and 2.0 mm, respectively. In CMs-only, cellular injury as assessed by lactate dehydrogenase (LDH) release increased significantly during hypoxia and further upon reoxygenation when the distance was 2.0 mm compared to 0.5 and 1.0 mm. When ECs and CMs were in nearly direct contact (0.5 mm), there was only a mild attenuation of the reoxygenation injury of CMs following hypoxia. This attenuation was significantly increased when the spatial distance was 1.0 mm. With 2.0 mm distance, ECs attenuated CM injury during both hypoxia and hypoxia/reoxygenation, indicating that sufficient culture distancing is necessary for ECs to crosstalk with CMs, so that secreted signal molecules can circulate and fully stimulate protective pathways. Our findings suggest, for the first time, that optimizing the EC/CM co-culture spatial environment is necessary to provide a favorable in vitro model for testing the role of ECs in CM-protection against simulated ischemia/reperfusion injury. The goal of this report is to provide a step-by-step approach for investigators to use this important model to their advantage.

Development of a Cell Co-Culture Model to Mimic Cardiac Ischemia/Reperfusion In Vitro

Spatial distance is a key parameter in assessing hypoxia/reoxygenation injury in a co-culture model of separate endothelial and cardiomyocyte cell layers, suggesting, for the first time, that optimizing the co-culture spatial environment is necessary to provide a favorable in vitro model for testing the role of endothelial cells in cardiomyocyte protection.

Entwicklung eines Zell-Co-Kultur-Modells zur Nachahmung von kardialer Ischämie/Reperfusion in vitro

Ischemic heart disease is the leading cause of death and disability worldwide. Reperfusion causes additional injury beyond ischemia. Endothelial cells ...

Die hypoxische ischämischen Enzephalopathie Model of Perinatal Ischämie

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