Name: an improved method for rapid intubation of the trachea in mice
Uploaded: 2016-02-22T14:00:00
Description: Watch this Scientific Journal Video about An Improved Method for Rapid Intubation of the Trachea in Mice at JoVE.com

The authors thank Brian Johnson of the Histology and Imaging Core at the University of Washington for help with the trichrome staining and analysis. This work was supported by NIH grants HL098067 and HL089455.

The Institutional Animal Care and Use Committees (IACUC) at the University of Washington and Cedars-Sinai Medical Center have approved the animal work necessary for these studies.
1. Preparation
<ol>
	<li>Sterilize both the blunt end forceps and the depressor via autoclave.</li>
	<li>Using a biological safety cabinet, prepare a working stock of BLM in PBS from the lyophilized powder.&#160; Sonicate the solution for 10 min at 35 Khz to assure even mixing. 
	Note: A total volume of between 30 and 45 &#181;l i...

<ol>
	<li>Hyde, D. M., Hamid, Q., Irvin, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomy,+pathology,+and+physiology+of+the+tracheobronchial+tree:+emphasis+on+the+distal+airways.">Anatomy, pathology, and physiology of the tracheobronchial tree: emphasis on the distal airways.</a> J Allergy Clin Immunol. 124, S72-S77 (2009).</li><li>Rosenthal, N., Brown, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mouse+ascending:+perspectives+for+human-disease+models.">The mouse ascending: perspectives for human-disease models.</a> Nat Cell Biol. 9, 993-999 (2007).</li><li>Peters, L. L., 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=The+mouse+as+a+model+for+human+biology:+a+resource+guide+for+complex+trait+analysis.">The mouse as a model for human biology: a resource guide for complex trait analysis.</a> Nat Rev Genet. 8, 58-69 (2007).</li><li>Baron, R. M., Choi, A. J., Owen, C. A., Choi, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetically+manipulated+mouse+models+of+lung+disease:+potential+and+pitfalls.">Genetically manipulated mouse models of lung disease: potential and pitfalls.</a> Am J Physiol Lung Cell Mol Physiol. 302, 485-497 (2012).</li><li>Sharma, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+respiratory+distress+syndrome.">Acute respiratory distress syndrome.</a> BMJ Clin Evid. 2010, (2010).</li><li>Saguil, A., Fargo, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+respiratory+distress+syndrome:+diagnosis+and+management.">Acute respiratory distress syndrome: diagnosis and management.</a> Am Fam Physician. 85, 352-358 (2012).</li><li>Wilson, M. S., Wynn, T. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulmonary+fibrosis:+pathogenesis,+etiology+and+regulation.">Pulmonary fibrosis: pathogenesis, etiology and regulation.</a> Mucosal Immunol. 2, 103-121 (2009).</li><li>Wuyts, W. A., 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=The+pathogenesis+of+pulmonary+fibrosis:+a+moving+target.">The pathogenesis of pulmonary fibrosis: a moving target.</a> Eur Respir J. 41, 1207-1218 (2013).</li><li>Mouratis, M. A., Aidinis, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modeling+pulmonary+fibrosis+with+bleomycin.">Modeling pulmonary fibrosis with bleomycin.</a> Curr Opin Pulm Med. 17, 355-361 (2011).</li><li>Moeller, A., Ask, K., Warburton, D., Gauldie, J., Kolb, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+bleomycin+animal+model:+a+useful+tool+to+investigate+treatment+options+for+idiopathic+pulmonary+fibrosis?.">The bleomycin animal model: a useful tool to investigate treatment options for idiopathic pulmonary fibrosis?.</a> Int J Biochem Cell Biol. 40, 362-382 (2008).</li><li>Myll&#228;rniemi, M., Kaarteenaho, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pharmacological+treatment+of+idiopathic+pulmonary+fibrosis+-+preclinical+and+clinical+studies+of+pirfenidone,+nintedanib,+and+N-acetylcysteine.">Pharmacological treatment of idiopathic pulmonary fibrosis - preclinical and clinical studies of pirfenidone, nintedanib, and N-acetylcysteine.</a> European Clinical Respiratory Journal. 2, (2015).</li><li>Reinert, T., Baldotto, C. S. d. R., Nunes, F. A. P., Scheliga, A. A. d. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bleomycin-Induced+Lung+Injury.">Bleomycin-Induced Lung Injury.</a> Journal of Cancer Research. 2013, 1-9 (2013).</li><li>Lakatos, H. F., 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=Oropharyngeal+aspiration+of+a+silica+suspension+produces+a+superior+model+of+silicosis+in+the+mouse+when+compared+to+intratracheal+instillation.">Oropharyngeal aspiration of a silica suspension produces a superior model of silicosis in the mouse when compared to intratracheal instillation.</a> Exp Lung Res. 32, 181-199 (2006).</li><li>Helms, M. N., Torres-Gonzalez, E., Goodson, P., Rojas, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+tracheal+instillation+of+solutes+into+mouse+lung.">Direct tracheal instillation of solutes into mouse lung.</a> J Vis Exp. , (2010).</li><li>Osier, M., Oberdorster, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intratracheal+inhalation+vs+intratracheal+instillation:+differences+in+particle+effects.">Intratracheal inhalation vs intratracheal instillation: differences in particle effects.</a> Fundam Appl Toxicol. 40, 220-227 (1997).</li><li>Driscoll, K. E., 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=Intratracheal+instillation+as+an+exposure+technique+for+the+evaluation+of+respiratory+tract+toxicity:+Uses+and+Limitations.">Intratracheal instillation as an exposure technique for the evaluation of respiratory tract toxicity: Uses and Limitations.</a> Toxicol Sci. 55, 24-35 (2000).</li><li>MacDonald, K. D., Chang, H. Y., Mitzner, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+improved+simple+method+of+mouse+lung+intubation.">An improved simple method of mouse lung intubation.</a> J Appl Physiol (1985). 106, 984-987 (1985).</li><li>Spoelstra, E. 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=A+novel+and+simple+method+for+endotracheal+intubation+of+mice.">A novel and simple method for endotracheal intubation of mice.</a> Lab Anim. 41, 128-135 (2007).</li><li>Cai, Y., Kimura, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+intratracheal+intubation+to+study+the+pathology+and+physiology+of+mouse+lung.">Noninvasive intratracheal intubation to study the pathology and physiology of mouse lung.</a> J Vis Exp. , e50601 (2013).</li><li>Starcher, B., WIlliams, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+method+for+intratracheal+instillation+of+endotoxin+into+the+lungs+of+mice.">A method for intratracheal instillation of endotoxin into the lungs of mice.</a> Lab Anim. 23, 234-240 (1989).</li><li>Daubeuf, F., Frossard, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Performing+bronchoalveolar+lavage+in+the+mouse.">Performing bronchoalveolar lavage in the mouse.</a> Curr Protoc Mouse Biol. 2, 167-175 (2012).</li><li>Li, Y., 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=Severe+lung+fibrosis+requires+an+invasive+fibroblast+phenotype+regulated+by+hyaluronan+and+CD44.">Severe lung fibrosis requires an invasive fibroblast phenotype regulated by hyaluronan and CD44.</a> J Exp Med. 208, 1459-1471 (2011).</li><li>Grazioli, 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=CYR61+(CCN1)+overexpression+induces+lung+injury+in+mice.">CYR61 (CCN1) overexpression induces lung injury in mice.</a> Am J Physiol Lung Cell Mol Physiol. 308, L759-L765 (2015).</li><li>Redente, E. F., 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=Tumor+necrosis+factor-alpha+accelerates+the+resolution+of+established+pulmonary+fibrosis+in+mice+by+targeting+profibrotic+lung+macrophages.">Tumor necrosis factor-alpha accelerates the resolution of established pulmonary fibrosis in mice by targeting profibrotic lung macrophages.</a> Am J Respir Cell Mol Biol. 50, 825-837 (2014).</li><li>Lawrenz, M. B., Fodah, R. A., Gutierrez, M. G., Warawa, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intubation-mediated+intratracheal+(IMIT)+instillation:+a+noninvasive,+lung-specific+delivery+system.">Intubation-mediated intratracheal (IMIT) instillation: a noninvasive, lung-specific delivery system.</a> J Vis Exp. , e52261 (2014).</li></ol>

In instances where aerosolization is impractical due to limited reagent availability, safety, or cost, direct tracheal administration is a superior method for delivery of exogenous agents into the lungs.16 Transtracheal instillation has been widely used to accomplish this; however, as with all surgical intervention, it also carries with it the potential for complications caused by the procedure itself, and not necessarily the agent being instilled.13 For these reasons, it has become...

In spite of some anatomical and physiological differences,1 murine models continue to be invaluable for modeling human biology and disease pathogenesis.2 From a husbandry standpoint, mice are easy to handle, have a low breeding time, an accelerated lifespan, and are relatively inexpensive to house. With the development of diverse genetic strains and strategies (e.g., conditional knock-outs, reporter mice, lineage-tracing approaches, etc.), as well as the wide range of available reagents (e.g., antibodies, recombinant proteins, inhibitors, etc.), mice have become an essential model vertebrate organism to uncover human homeostasis and disease processes.3
Mice have been especially valuable for studying pulmonary conditions, including acute lung injury (ALI) and pulmonary fibrosis.4 ALI in humans can be caused by trauma, injury, or sepsis and is characterized by epithelial and endothelial leak (i.e., edema), inflammation, and nascent fibrosis. In many patients, ALI progresses to its severe form, acute respiratory distress syndrome (ARDS), which often results in fibrosis and death due to respiratory failure.5,6 Pulmonary fibrosis is a progressive, fatal pathology characterized by the excess deposition of extracellular matrix, most notably type I collagen, leading to impaired lung function.7,8 Administration of bleomycin (BLM) is the most widely used and best characterized model for inducing ALI and fibrosis in experimental animals.9 Although BLM-induced pulmonary fibrosis in rodents does not recapitulate fully the human fibrotic phenotypes,10 mouse studies with this model have led to the discovery of many important factors influencing the onset and progression of disease.11
While the exact mechanism(s) behind BLM-induced fibrogenesis are unknown, the initiating injury is thought to arise from contact-dependent DNA strand breaks in the epithelial cells lining the conducting airways and alveoli, and in particular, type 1 pneumocytes.12 The need for direct contact between BLM and the pulmonary epithelium highlights the importance of a robust delivery route, and these concerns are also germane to a broad range of treatments targeted to the distal airways, including recombinant proteins, antibodies, siRNA, virus, bacteria, particulates, and more. Oropharyngeal aspiration (OPA) has been widely used for this purpose13, but a major a shortcoming of OPA is that some portion of the delivered agent may be swallowed into the gastrointestinal tract, thereby leading to imprecision in the administered dose. Another widely used approach is transtracheal instillation, which involves tracheostomy under strong anesthesia to expose the trachea and instillation of an agent directly into the respiratory tract.14 However, not only may such a procedure be undesirable due to its invasivity, but it is also time consuming, requires a fair bit of training, and causes a potent injury to the respiratory tract.15,16 Several protocols have been developed that involve the direct administration of agents into the trachea without the need for surgical intervention,16,17,18,19,20 but these methods involve extended recovery times caused by powerful anesthetics, the use of expensive equipment (i.e., otoscope/laryngoscope, commercially available procedure boards, fiber-optic wires, etc.), an excess of manipulation in the oral cavity, and uncertainty regarding the dosage.
This paper describes a relatively easy method of administration via intubation that allows a researcher to quickly, inexpensively, and reliably instill a reagent into the murine lung with limited risk of residual damage to the surrounding tissues.

<table border="0" cellpadding="0" cellspacing="0" width="1528">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:481px;">Bleomycin For Injection, 30 units/vial</td>
			<td style="width:304px;">APP Pharmaceuticals, LLC</td>
			<td style="width:139px;">103720</td>
			<td style="width:604px;">For best results, BLM should be suspended in PBS, aliquoted, and stored as single use lyophilzed aliquots</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Blunt End Forceps</td>
			<td style="width:304px;">N/A</td>
			<td style="width:139px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tongue Depressor (i.e. bent Valleylab Blade Electrode, 2.4&#34;)&#160;</td>
			<td style="width:304px;">Covidien</td>
			<td>E1551G</td>
			<td>Before use, create a 45 degree bend 1.5 cm&#160; from the blade tip. A suitable depressor can also be created from any metal implement of similar dimensions.&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Exel Safelet Catheter 22G X 1&#34;</td>
			<td style="width:304px;">Exel International</td>
			<td>26746</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1 mL Slip-tip Disposable Tuberculin Syringe (200/sp, 1600/ca)</td>
			<td style="width:304px;">BD</td>
			<td>309659</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">0.2ml Pipettor and Filter Tips</td>
			<td style="width:304px;">N/A</td>
			<td style="width:139px;">N/A</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:481px;">Fiber-Lite Illuminator. Model 181-1: Model 180 mated with Standard Dual Gooseneck illuminator</td>
			<td style="width:304px;">Dolan Jenner Industries, Inc.</td>
			<td style="width:139px;">181-1</td>
			<td>Lower output LED illuminators are not recommended as they fail to suficiently illuminate the trachea.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Intubation Board</td>
			<td style="width:304px;">N/A</td>
			<td style="width:139px;">N/A</td>
			<td>See Diagram 1.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Colored Label Tape: 0.5&#160;in. Wide</td>
			<td style="width:304px;">Fisherbrand</td>
			<td>15-901-15A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Oxygen&#160;</td>
			<td style="width:304px;">N/A</td>
			<td style="width:139px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphate-Buffered Saline, 1X</td>
			<td style="width:304px;">Corning</td>
			<td>21-040-CV</td>
			<td>Product should be sterile</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Non-Sterile Silk Black Braided Suture Spool, 91.4 m, Size 4-0</td>
			<td style="width:304px;">Harvard Apparatus</td>
			<td>517698</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Table Top Anesthesia Machine Isoflurane</td>
			<td style="width:304px;">Highland Medical Equipment</td>
			<td>N/A</td>
			<td>http://www.highlandmedical.net/</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Slide Top Induction Mouse Isoflurane Chamber</td>
			<td>MIP / Anesthesia Technologies</td>
			<td>AS-01-0530-SM</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FORANE (isoflurane, USP) Liquid For Inhalation 100 mL&#160;</td>
			<td style="width:304px;">Baxter</td>
			<td>1001936040</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#160;Nanozoomer Digital Pathology system</td>
			<td style="width:304px;">Hamamatsu</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">IgM ELISA Quantification Kit&#160;</td>
			<td style="width:304px;">Bethyl Laboratories</td>
			<td style="width:139px;">E90-101</td>
			<td></td>
		</tr>
	</tbody>
</table>

an improved method for rapid intubation of the trachea in mice

Despite some anatomical and physiological differences, mouse models continue to be an essential tool for studying human lung disease. Bleomycin toxicity is a commonly used model to study both acute lung injury and fibrosis, and multiple methods have been developed for administering bleomycin (and other toxic agents) into the lungs. However, many of these approaches, such as transtracheal instillation, have inherent drawbacks, including the need for strong anesthetics and survival surgery. This paper reports a quick, reproducible method of intratracheal intubation that involves mild inhaled anesthesia, visualization of the trachea, and the use of a surrogate spirometer to confirm exposure. As a proof of concept, 8-12 week old C57BL/6 mice were administered either 2.0 U/kg of bleomycin or an equivalent volume of PBS, and both damage and fibrotic endpoints were measured post-exposure. This procedure allows researchers to treat a large cohort of mice in a relatively short period with little expense and minimal post-procedure care.

Intubated mice were monitored daily for weight loss and distress, and sacrificed 4, 10 or 17 days later via intraperitoneal injection of 2.5% 2,2,2-tribromoethanol. Bronchoalveolar lavage (BAL) was collected in three washes of PBS as described elsewhere 21, and the right lung was fixed in 10% formalin, paraffin embedded, and stained with Masson&#39;s Trichrome by the University of Washington Histology and Imaging Core 22.
<p class="jove_content"...

Watch this Scientific Journal Video about An Improved Method for Rapid Intubation of the Trachea in Mice at JoVE.com

An Improved Method for Rapid Intubation of the Trachea in Mice

This article presents a rapid and simple method for administering bleomycin directly into the mouse trachea via intubation. Key advantages of this method are that it is highly reproducible, easy to master, and does not require specialized equipment or lengthy recovery times.

Despite some anatomical and physiological differences, mouse models continue to be an essential tool for studying human lung disease. Bleomycin toxicity ...

The overall goal of this procedure, is to provide quick, easy and reliable administration of reagents into the murine lungs via intubation. The method also limits the risk of residual damage to the surrounding tissues and is inexpensive. This method can help answer key questions in the basic lung biology and mechanisms of disease fields.Such as acute lung injury and fibrogenesis. The main advantages of this technique are that is highly re-produceable, easy to master, does not require specialized equipment or lengthy recovery times. The procedure must be performed using sterilized tools.So autoclave both the blunt end forceps and the depressor. In a sterilized hood, prepare a working stock of re-agent to administer via the intubation. A bolus volume between 30 and 45 microliters is recommended.Sonicate the solution for 10 minutes at 35 kilohertz to assure even mixing. Now, prepare the workspace. Designate at least a square meter of space for the workspace itself.As well as distinct locations for the animals both before and after the procedure. Now, prepare a procedure board. This customized model is cut from an aluminium sheet and reinforced by a T bracket.Similar commercial boards are also available. Using a few strips of tape, fix the base of the procedure board to the bench, so it will be directly in front of the experimenter. Then tie a length of 4.0 suture between the two positioning screws of the procedure board.Next, build a spirometer. Remove the plungers from three one-milliliter syringes. Then load up to 60 microliters of PBS into the top of each syringe barrel.Loosely secure one of these three syringes to the hub of a catheter. When in use, air emanating from the trachea, will cause the PBS in the barrel to rise and fall. Place this next to the procedure board.Place the other two additional syringes within reach to serve as backups. Next, into a fourth syringe, aspirate 300 microliters of air, and place it to one side of the board. Also prepare a few six inch lengths of tape to secure the animal to the board.Then set up an isoflurane chamber if needed. Attach the oxygen, isoflurane and vacuum lines to the appropriate ports on the chamber and the clearance vacuum. Begin with anesthetizing the mouse.Importantly because factors such as the age, weight, and health of the animal can all modify the response the anesthetics, each lab should optimize the isoflurane exposure to meet their own needs. While waiting, load the bolus of reagent into a pipette tip, and set it aside. When the mouse is sedated, suspend it by it's upper incisors from the thread on the procedure platform, with the animals dorsum lying flat against the platform surface.Now, being careful not to restrict ventilation, loosely tape the lower portion of the the thoracic cavity, just above the diaphragm, to the platform, to keep the animal aligned during the procedure. Next, set the gooseneck illuminator to 80 to 100%Position the light one to two centimeters from the surface of the skin near the solar plexus and regularly check that it isn't over heating the skin. From behind the platform use the blunt end forceps to locate the tongue.Then being careful to avoid the lower incisors, gently grip and draw the tongue out of the oral cavity. While securing the tongue, flatten it with the depressor In the non-dominant hand, allowing the forceps to release. Now, guide the gooseneck approximately from the solar plexus to the main stem bronchi to illuminate the trachea.The trachea can also be easily distinguished by the action of respiration, which will cause the light to fluctuate in intensity as it leaves the trachea. When correctly positioned, the trachea can be seen as a central pin of light, with minimal ambient light in the oral cavity itself. The catheter should not enter the oral cavity until the view of the trachea is ideal.The trachea cannot be brought into view through manipulation of either the light source or the depressor. Researchers should release the tongue and re-attempt the procedure. Next, angle the syringe to follow the natural path of the trachea.And lower the 22 gauge catheter tip, with the attached syringe containing the PBS, straight into the lumen. Now, feed the catheter in an additional five millimeters and remove the tongue depressor. If correctly placed the PBS bubble in the barrel will begin to rise and fall with each breath.Be patient when looking for this indicator as both heavy and light sedation can modify the frequency of respiration. Then shift the syringe to the non dominant hand. While gripping the hub, gently remove the syringe leaving the catheter in place.From the dominant hand, deposit the prepared bolus of reagent directly into the center of the catheter hub. Then attach the second syringe with 300 microliters of air and eject the air into the hub. This will help ensure that the bolus is well distributed in the lungs.Now, remove the syringe and replace it with a syringe containing the bubble of PBS. The bubble will continue to rise and fall if the procedure has been performed successfully. Now, remove the catheter and tape.And place the animal in a dry warm place until it regains consciousness. Typically within a couple of minutes. Intubated mice were monitored daily for weight loss.Mice were collected at four, 10, and 17 days post intratracheal intubation with bleomycin. Bronchoalveolar lavage was collected from these lungs and analyzed. Elevated levels of IgM demonstrated a significant time dependent increase in lung permeability indicative of epithelial and/or endothelial barrier dysfunction.The right lungs were fixed and stained with Masson's trichrome. The fibrogenic response, a well established marker of total collagen content, was quantified. The histology sections evidenced treatment dependent thickening of the pulmonary interstitium, and increases in fibrotic lesions.Once mastered this technique can be done in under a minute if properly performed. While attempting this procedure it's important to remember that manipulation of the soft tissues surrounding the trachea is not necessary or recommended. And it can compromise both the health of the animal, and the integrity of the experiment.

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Medicine

Endotracheal Intubation in Mice via Direct Laryngoscopy Using an Otoscope

Mice, both wildtype and transgenic, are the principal mammalian model in biomedical research currently. Intubation and mechanical ventilation are necessary for whole animal experiments that require surgery under deep anesthesia or measurements of lung function. Tracheostomy has been the standard for intubating the airway in these mice to allow mechanical ventilation. Orotracheal intubation has been reported but has not been successfully used in many studies because of the substantial technical difficulty or a requirement for highly specialized and expensive equipment. Here we report a technique of direct laryngoscopy using an otoscope fitted with a 2.0 mm speculum and using a 20 G&#160;intravenous catheter as an endotracheal tube. We have used this technique extensively and reliably to intubate and conduct accurate assessments of lung function in mice. This technique has proven safe, with essentially no animal loss in experienced hands. Moreover, this technique can be used for repeated studies of mice in chronic models.

Endotracheal Intubation in Mice via Direct Laryngoscopy Using an Otoscope

We have developed a simple, reliable, and relatively inexpensive method for endotracheal intubation in mice via direct laryngoscopy using an otoscope with a 2.0 mm speculum. This technique is atraumatic and can be used for repeated measurements in chronic experiments. We find it superior to tracheostomy or previously reported nonsurgical techniques.

Mice, both wildtype and transgenic, are the principal mammalian model in biomedical research currently. Intubation and mechanical ventilation are ...

A Simple Method of Mouse Lung Intubation

A simple procedure to intubate mice for pulmonary function measurements would have several advantages in longitudinal studies with limited numbers or expensive animal. One of the reasons that this is not done more routinely is that it is relatively difficult, despite there being several published studies that describe ways to achieve it. In this paper we demonstrate a procedure that eliminates one of the major hurdles associated with this intubation, that of visualizing the trachea during the entire time of intubation. The approach uses a 0.5 mm fiberoptic light source that serves as an introducer to direct the intubation cannula into the mouse trachea. We show that it is possible to use this procedure to measure lung mechanics in individual mice over a time course of at least several weeks. The technique can be set up with relatively little expense and expertise, and it can be routinely accomplished with relatively little training. This should make it possible for any laboratory to routinely carry out this intubation, thereby allowing longitudinal studies in individual mice, thereby minimizing the number of mice needed and increasing the statistical power by using each mouse as its own control.

This paper describes a striaghforward and efficient method of intubating mice for pulmonary function measurements or pulmonary instillation, that allows the mice to recover and be studied at later times. The procedure involves an inexpensive fiberoptic light source that directly illuminates the trachea.

A  simple procedure to intubate mice for pulmonary function measurements would  have several advantages in longitudinal studies with limited numbers or  ...

Improved Method for the Establishment of an In Vitro Blood-Brain Barrier Model Based on Porcine Brain Endothelial Cells

The aim of this protocol presents an optimized procedure for the purification and cultivation of pBECs and to establish in vitro blood-brain barrier (BBB) models based on pBECs in mono-culture (MC), MC with astrocyte-conditioned medium (ACM), and non-contact co-culture (NCC) with astrocytes of porcine or rat origin. pBECs were isolated and cultured from fragments of capillaries from the brain cortices of domestic pigs 5-6 months old. These fragments were purified by careful removal of meninges, isolation and homogenization of grey matter, filtration, enzymatic digestion, and centrifugation. To further eliminate contaminating cells, the capillary fragments were cultured with puromycin-containing medium. When 60-95% confluent, pBECs growing from the capillary fragments were passaged to permeable membrane filter inserts and established in the models. To increase barrier tightness and BBB characteristic phenotype of pBECs, the cells were treated with the following differentiation factors: membrane permeant 8-CPT-cAMP (here abbreviated cAMP), hydrocortisone, and a phosphodiesterase inhibitor, RO-20-1724 (RO). The procedure was carried out over a period of 9-11 days, and when establishing the NCC model, the astrocytes were cultured 2-8 weeks in advance. Adherence to the described procedures in the protocol has allowed the establishment of endothelial layers with highly restricted paracellular permeability, with the NCC model showing an average transendothelial electrical resistance (TEER) of 1249 &#177; 80 &#937; cm2, and paracellular permeability (Papp) for Lucifer Yellow of 0.90 10-6 &#177; 0.13 10-6 cm sec-1 (mean &#177; SEM, n=55). Further evaluation of this pBEC phenotype showed good expression of the tight junctional proteins claudin 5, ZO-1, occludin and adherens junction protein p120 catenin. The model presented can be used for a range of studies of the BBB in health and disease and, with the highly restrictive paracellular permeability, this model is suitable for studies of transport and intracellular trafficking.

Improved Method for the Establishment of an In Vitro Blood-Brain Barrier Model Based on Porcine Brain Endothelial Cells

The aim of the protocol is to present an optimized procedure for the establishment of an in vitro blood-brain barrier (BBB) model based on primary porcine brain endothelial cells (pBECs). The model shows high reproducibility, high tightness, and is suitable for studies of transport and intracellular trafficking in drug discovery.

The aim of this protocol presents an optimized procedure for the purification and cultivation of pBECs and to establish in vitro blood-brain barrier (BBB) ...

Subclavian Vein Puncture As an Alternative Method of Blood Sample Collection in Rats

Blood collection with enough blood volume is essential in animal experiments. Blood collection from the tail vein of rats is popular and less stressful compared to other more aggressive methods such as retro-orbital plexus sample collection. However, this blood collection method is sometimes limited by an unsatisfactory success rate. Here, we introduce a method for blood collection through the subclavian vein puncture. The subclavian vein is located just under the clavicle and this vein is large enough to fulfill the volume requirements of blood collection. Our results show that this method is safe and applicable for blood collection sampling with the required blood volume. Blood collection through the subclavian vein puncture could serve as an alternative blood collection method in case of failed tail vein blood sampling in rats.

Here, we present a protocol to collect blood samples from the rat subclavian vein.

Blood collection with enough blood volume is essential in animal experiments. Blood collection from the tail vein of rats is popular and less stressful ...

A Revised Method for Inducing Secondary Lymphedema in the Hindlimb of Mice

Animal models are of paramount importance in the research of lymphedema in order to understand the pathophysiology of the disease but also to explore potential treatment options. This mouse model allows researchers to induce significant lymphedema lasting at least 8 weeks. Lymphedema is induced using a combination of fractioned radiotherapy and surgical ablation of lymphatics. This model requires that the mice get a dose of 10 Gray (Gy) radiation before and after surgery. The surgical part of the model involves ligation of three lymph vessels and extraction of two lymph nodes from the mouse hindlimb. Having access to microsurgical tools and a microscope is essential, due to the small anatomical structures of mice. The advantage of this model is that it results in statistically significant lymphedema, which provides a good basis for evaluating different treatment options. It is also a great and easily available option for microsurgical training. The limitation of this model is that the procedure can be time consuming, especially if not practiced in advance. The model results in objectively quantifiable lymphedema in mice, without causing severe morbidity and has been tested in three separate projects.

This animal model enables researchers to induce statistically significant secondary lymphedema in the hindlimb of mice, lasting at least 8 weeks. The model can be used to study the pathophysiology of lymphedema and to investigate novel treatment options.

Animal models are of paramount importance in the research of lymphedema in order to understand the pathophysiology of the disease but also to explore ...

Repeated Orotracheal Intubation in Mice

The literature describes several methods for mouse intubation that either require visualization of the glottis through the oral cavity or incision in the ventral neck for direct confirmation of cannula placement in the trachea. The relative difficulty or the tissue trauma induced to the subject by such procedures can be an impediment to an investigator&#8217;s ability to perform longitudinal studies. This article illustrates a technique in which physical manipulation of the mouse following the use of a depilatory to remove hair from the ventral neck permits transcutaneous visualization of the trachea for orotracheal intubation regardless of degree of skin pigmentation. This method is innocuous to the subject and easily achieved with a limited understanding of murine anatomy. This refined approach facilitates repeated intubation, which may be necessary for monitoring progression of disease or instillation of treatments. Using this method may result in a reduction of the number of animals and technical skill required to measure lung function in mouse models of respiratory disease.

The goal of this article is to describe a refined method of intubation of the laboratory mouse. The method is noninvasive and, therefore, ideal for studies that require serial monitoring of respiratory function and/or instillation of treatments into the lung.

The literature describes several methods for mouse intubation that either require visualization of the glottis through the oral cavity or incision in the ...

Semi-Minimal Invasive Method to Induce Myocardial Infarction in Rats and the Assessment of Cardiac Function by an Isolated Working Heart System

Myocardial infarction (MI) remains the main contributor to morbidity and mortality worldwide. Therefore, research on this topic is mandatory. An easily and highly reproducible MI induction procedure is required to obtain further insight and better understanding of the underlying pathological changes. This procedure can also be used to evaluate the effects or potency of new and promising treatments (as drugs or interventions) in acute MI, subsequent remodeling and heart failure (HF). After intubation and pre-operative preparation of the animal, an anesthetic protocol with isoflurane was performed, and the surgical procedure was conducted&#160;quickly. Using a minimally invasive approach, the left anterior descending artery (LAD) was located and occluded by a ligature. The occlusion can be performed acutely for subsequent reperfusion (ischemia/reperfusion injury). Alternatively, the vessel can be ligated permanently to investigate the development of chronic MI, remodeling or HF. Despite common pitfalls, the drop-out rates are minimal. Various treatments such as remote ischemic conditioning can be examined for their cardioprotective potential pre-, peri- and post-operatively. The post-operative recovery was quick as the anesthesia was precisely controlled and the duration of the operation was short. Post-operative analgesia was administered for three days. The minimally invasive procedure reduces the risk of infection and inflammation. Furthermore, it facilitates rapid recovery. The &#8220;working heart&#8221; measurements were performed ex vivo and enabled precise control of preload, afterload and flow. This procedure requires specific equipment and training for adequate performance. This manuscript provides a detailed step-by-step introduction for conducting these measurements.

This article presents an efficient method to perform myocardial ischemia and subsequent chronic reperfusion in rats using a minimally invasive approach. In addition, left ventricular hemodynamic function of rats is assessed by echocardiography and isolated working heart methods.&#160;

Myocardial infarction (MI) remains the main contributor to morbidity and mortality worldwide. Therefore, research on this topic is mandatory. An easily ...

A Modified Simple Method for Induction of Myocardial Infarction in Mice

Myocardial infarction (MI) represents one of the leading causes of death. MI models are widely used for investigating the pathomechanisms of post-MI remodeling and evaluation of novel therapeutics. Different methods (e.g., isoproterenol treatment, cryoinjury, coronary artery ligation, etc.) have been used to induce MI. Compared with isoproterenol treatment and cryoinjury, coronary artery ligation may better reflect the ischemic response and chronic remodeling after MI. However, traditional methods for coronary ligation in mice are technically challenging. The current study describes a simple and efficient process for induction of MI in mice with readily available materials. The mouse chest skin was cut open under stable anesthesia. The heart was immediately externalized through the intercostal space after blunt separation of the pectoralis major and pectoralis minor. The left anterior descending branch (LAD) was ligated with a 6-0 suture 3 mm from its origin. Following LAD ligation, staining with 2,3,5-Triphenyltetrazolium chloride (TTC) indicated successful induction of MI and temporal changes of post-MI scar size. Meanwhile, survival analysis results showed overt mortality within 7 days after MI, mainly due to cardiac rupture. Moreover, post-MI echocardiographic assessment demonstrated successful induction of contractile dysfunction and ventricular remodeling. Once mastered, an MI model can be established in mice within 2-3 min with readily available materials.

Under adequate anesthesia, the mouse heart was externalized through the intercostal space, and myocardial infarction was successfully induced by ligating the left anterior descending artery (LAD) using materials readily available in most laboratories.

Myocardial infarction (MI) represents one of the leading causes of death. MI models are widely used for investigating the pathomechanisms of post-MI ...

Endotracheal Intubation Using a Flexible Intubation Endoscope as a Standardized Model for Safe Airway Management in Swine

Endotracheal intubation is often a basic requirement for translational research in porcine models for various interventions that require a secured airway or high ventilation pressures. Endotracheal intubation is a challenging skill,&#160;requiring a minimum number of successful endotracheal intubations to achieve a high success rate under optimal conditions, which is often unachievable for non-anaesthesiology researchers. Due to the specific porcine airway anatomy, a difficult airway can usually be assumed. The impossibility of establishing a secure airway can result in injury, adverse events, or death of the laboratory animal. Using a prospective, randomized, controlled evaluation approach, it has been shown that fiberoptic-assisted endotracheal intubation takes longer but has a higher first-pass success rate than conventional intubation without causing clinically relevant drops in oxygen saturation. This model presents a standardized regimen for endoscopically guided endotracheal intubation, providing a secured airway, especially for researchers who are inexperienced in the technique of endotracheal intubation via direct laryngoscopy. This procedure is expected to minimize animal suffering and unnecessary animal losses.

The use of pigs in research has increased in recent years. Nevertheless, pigs are characterized by difficult airway anatomy. By demonstrating how to perform endoscopically guided endotracheal intubation, the present protocol aims to further increase laboratory animals' safety to avoid animal suffering and unnecessary death.

Endotracheal intubation is often a basic requirement for translational research in porcine models for various interventions that require a secured airway ...

Quantitative Analysis of Liver Stiffness Distribution

A Three-Dimensional Digital Model for Early Diagnosis of Hepatic Fibrosis Based on Magnetic Resonance Elastography

Hepatic fibrosis is an early stage of liver cirrhosis, and there are no better non-invasive and convenient methods for the detection and evaluation of the disease. Despite the good progress made with the liver stiffness map (LSM) based on magnetic resonance elastography (MRE), there are still some limitations that need to be overcome, including manual focus determination, manual selection of regions of interest (ROIs), and discontinuous LSM data without structural information, which makes it impossible to evaluate the liver as a whole. In this study, we propose a novel three-dimensional (3D) digital model for the early diagnosis of hepatic fibrosis based on MRE.
MRE is a non-invasive imaging technique that employs magnetic resonance imaging (MRI) to measure the liver stiffness at the scanning site through human-computer interaction. Studies have indicated a significant positive correlation between the LSM obtained through MRE and the degree of hepatic fibrosis. However, for clinical purposes, a comprehensive and precise quantification of the degree of hepatic fibrosis is necessary. To address this, the concept of Liver Stiffness Distribution (LSD) was proposed in this study, which refers to the 3D stiffness volume of each liver voxel obtained by the alignment of 3D liver tissue images and MRE indicators. This provides a more effective clinical tool for the diagnosis and treatment of hepatic fibrosis.

Author Spotlight: Advancing Hepatic Fibrosis Diagnosis Using Magnetic Resonance Elastography and AI 

The objective of this study was to develop a novel three-dimensional digital model for the early diagnosis of hepatic fibrosis, which includes the stiffness of each voxel in the patient's liver and can thus, be used to calculate the distribution ratio of the patient's liver at different fibrosis stages.

Hepatic fibrosis is an early stage of liver cirrhosis, and there are no better non-invasive and convenient methods for the detection and evaluation of the ...