Name: a ligated intestinal loop model in anesthetized specific pathogen free chickens to study clostridium perfringens virulence
Uploaded: 2018-10-11T12:30:00
Description: Watch this Scientific Journal Video about A Ligated Intestinal Loop Model in Anesthetized Specific Pathogen Free Chickens to Study Clostridium Perfringens Virulence at JoVE.com

This work was supported by the Chair in Poultry Research (M. Boulianne) from the Faculty of Veterinary Medicine of the Universit&#233; de Montr&#233;al. Drs. Boulianne and Parent developed the model. Drs. Boulianne and Parent performed the surgeries. Dr. Burns assisted in developing the anesthesia protocol. Dr. Parent edited the video and wrote the manuscript. Drs Burns, Desrochers and Boulianne edited the manuscript.

All procedures with live animal use were authorized by the Ethical Committee of the Faculty of Veterinary Medicine, Universit&#233; de Montr&#233;al (C&#201;UA, &#39;Comit&#233; d&#39;&#233;thique de l&#39;utilisation des Animaux&#39;).
1. Considerations Before Surgery
<ol>
	<li>Select 10 weeks old specific pathogen free (SPF) leghorn chickens for the surgery. 
	NOTE: Their weight must be between 1.0 and 1.2 kg.</li>
	<li>Withdraw the feed 12 h prior to the procedures to empty the intes...

<ol>
	<li>Vitale, A., Chiarotti, F., Alleva, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+animal+models+in+disease+research.">The use of animal models in disease research.</a> Rare diseases and orphan drugs. 2 (1), 1-4 (2015).</li><li>Uzal, F. 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=Animal+models+to+study+the+pathogenesis+of+human+and+animal+Clostridium+perfringens+infections.">Animal models to study the pathogenesis of human and animal Clostridium perfringens infections.</a> Veterinary Microbiology. , (2015).</li><li>Bernier, G., Phaneuf, J. B., Filion, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Necrotic+enteritis+in+broiler+chickens.+III.+Study+of+the+factors+favoring+the+multiplication+of+Clostridium+perfringens+and+the+experimental+transmission+of+the+disease.">Necrotic enteritis in broiler chickens. III. Study of the factors favoring the multiplication of Clostridium perfringens and the experimental transmission of the disease.</a> Canadian Journal of Comparative Medicine. 41 (1), 112-116 (1977).</li><li>Al-Sheikhly, F., Truscott, R. 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+pathology+of+necrotic+enteritis+of+chickens+following+infusion+of+broth+cultures+of+Clostridium+perfringens+into+the+duodenum.">The pathology of necrotic enteritis of chickens following infusion of broth cultures of Clostridium perfringens into the duodenum.</a> Avian Diseases. 21 (2), 230-240 (1977).</li><li>Wicker, D. L., Iscrigg, W. N., Trammell, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+control+and+prevention+of+necrotic+enteritis+in+broilers+with+zinc+bacitracin.">The control and prevention of necrotic enteritis in broilers with zinc bacitracin.</a> Poultry Science. 56 (4), 1229-1231 (1977).</li><li>Keyburn, A. 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=NetB,+a+new+toxin+that+is+associated+with+avian+necrotic+enteritis+caused+by+Clostridium+perfringens.">NetB, a new toxin that is associated with avian necrotic enteritis caused by Clostridium perfringens.</a> PLoS Pathog. 4 (2), e26 (2008).</li><li>Timbermont, 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=Origin+of+Clostridium+perfringens+isolates+determines+the+ability+to+induce+necrotic+enteritis+in+broilers.">Origin of Clostridium perfringens isolates determines the ability to induce necrotic enteritis in broilers.</a> Comp Immunol Microbiol Infect Dis. 32 (6), 503-512 (2009).</li><li>Paradis, M. 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=Efficacy+of+avilamycin+for+the+prevention+of+necrotic+enteritis+caused+by+a+pathogenic+strain+of+Clostridium+perfringens+in+broiler+chickens.">Efficacy of avilamycin for the prevention of necrotic enteritis caused by a pathogenic strain of Clostridium perfringens in broiler chickens.</a> Avian Pathol. 45 (3), 365-369 (2016).</li><li>Valgaeren, B., 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=Lesion+development+in+a+new+intestinal+loop+model+indicates+the+involvement+of+a+shared+Clostridium+perfringens+virulence+factor+in+haemorrhagic+enteritis+in+calves.">Lesion development in a new intestinal loop model indicates the involvement of a shared Clostridium perfringens virulence factor in haemorrhagic enteritis in calves.</a> Journal of Comparative Pathology. 149 (1), 103-112 (2013).</li><li>Goossens, 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=The+C-terminal+domain+of+Clostridium+perfringens+alpha+toxin+as+a+vaccine+candidate+against+bovine+necrohemorrhagic+enteritis.">The C-terminal domain of Clostridium perfringens alpha toxin as a vaccine candidate against bovine necrohemorrhagic enteritis.</a> Vet Res. 47 (1), 52 (2016).</li><li>Goossens, 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=Toxin-neutralizing+antibodies+protect+against+Clostridium+perfringens-induced+necrosis+in+an+intestinal+loop+model+for+bovine+necrohemorrhagic+enteritis.">Toxin-neutralizing antibodies protect against Clostridium perfringens-induced necrosis in an intestinal loop model for bovine necrohemorrhagic enteritis.</a> BMC Vet Res. 12 (1), 101 (2016).</li><li>Parent, E., Archambault, M., Charlebois, A., Bernier-Lachance, J., Boulianne, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+chicken+intestinal+ligated+loop+model+to+study+the+virulence+of+Clostridium+perfringens+isolates+recovered+from+antibiotic-free+chicken+flocks.">A chicken intestinal ligated loop model to study the virulence of Clostridium perfringens isolates recovered from antibiotic-free chicken flocks.</a> Avian Pathol. 46 (2), 138-149 (2017).</li><li>Janvilisri, 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=Temporal+differential+proteomes+of+Clostridium+difficile+in+the+pig+ileal-ligated+loop+model.">Temporal differential proteomes of Clostridium difficile in the pig ileal-ligated loop model.</a> PLoS One. 7 (9), e45608 (2012).</li><li>Aabo, 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=Development+of+an+in+vivo+model+for+study+of+intestinal+invasion+by+Salmonella+enterica+in+chickens.">Development of an in vivo model for study of intestinal invasion by Salmonella enterica in chickens.</a> Infection and Immunity. 68 (12), 7122-7125 (2000).</li><li>Meurens, 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=Early+immune+response+following+Salmonella+enterica+subspecies+enterica+serovar+Typhimurium+infection+in+porcine+jejunal+gut+loops.">Early immune response following Salmonella enterica subspecies enterica serovar Typhimurium infection in porcine jejunal gut loops.</a> Vet Res. 40 (1), 5 (2009).</li><li>Gerdts, V., 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=Multiple+intestinal+'loops'+provide+an+in+vivo+model+to+analyse+multiple+mucosal+immune+responses.">Multiple intestinal 'loops' provide an in vivo model to analyse multiple mucosal immune responses.</a> J Immunol Methods. 256 (1-2), 19-33 (2001).</li><li>Wade, B., 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+adherent+abilities+of+Clostridium+perfringens+strains+are+critical+for+the+pathogenesis+of+avian+necrotic+enteritis.">The adherent abilities of Clostridium perfringens strains are critical for the pathogenesis of avian necrotic enteritis.</a> Vet Microbiol. 197, 53-61 (2016).</li><li>Cooper, K. K., 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=Virulence+for+chickens+of+Clostridium+perfringens+isolated+from+poultry+and+other+sources.">Virulence for chickens of Clostridium perfringens isolated from poultry and other sources.</a> Anaerobe. 16 (3), 289-292 (2010).</li><li>Cooper, K. K., Songer, J. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Virulence+of+Clostridium+perfringens+in+an+experimental+model+of+poultry+necrotic+enteritis.">Virulence of Clostridium perfringens in an experimental model of poultry necrotic enteritis.</a> Veterinary Microbiology. 142 (3-4), 323-328 (2010).</li><li>Chalmers, G., Bruce, H. L., Toole, D. L., Barnum, D. A., Boerlin, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Necrotic+enteritis+potential+in+a+model+system+using+Clostridium+perfringens+isolated+from+field+outbreaks.">Necrotic enteritis potential in a model system using Clostridium perfringens isolated from field outbreaks.</a> Avian Diseases. 51 (4), 834-839 (2007).</li></ol>

Intestinal loops models have been described in numerous species to study host-pathogen interaction and pathogenesis of diseases caused by various intestinal pathogens, such as Clostridium perfringens, Clostridium difficile and Salmonella enterica7,9,13,14,15. It has also been used to analyze the mucosal immune response<sup class="xre...

The use of animal models to study infectious diseases affecting humans and animals is a central tool in assessing virulence factors regulating the pathogenesis of a specific condition as well as to elaborate strategies to prevent or cure diseases1. Despite numerous advantages of using animal models to study various diseases, ethical concerns regarding this practice are arising. Researchers need to minimize animal use while obtaining significant and valid results. The concept of the 3 Rs principles (Replace, Reduce and Refine) was elaborated to ensure that welfare issues were addressed in such trials. In chicken necrotic enteritis studies, in vivo chicken models are used to investigate the etiology, prevention, and treatments of this condition2,3,4,5. Pathogenic strains of C. perfringens carrying specific virulence factors, such as the NetB toxin6, are administered to cause necrotic enteritis in chickens7. The replacement principle is, therefore, difficult to achieve in such case as these virulence factors may not be as critical in other animal species. Most models for necrotic enteritis in chickens use a combination of risk factors, such as coccidiosis and altered diet to induce necrotic enteritis followed by gavage of broth culture containing large numbers of C. perfringens2. These models will induce the disease in a large number of chickens, and mortality can be important in such trials8, thus raising concerns about the reduction and refinement principles in animal research.
Intestinal ligated loops models are a desirable alternative for the study of diseases induced by intestinal pathogens with respect to the principle reduction, and refinement. In these models, intestinal segments called &#39;loops&#39; are created by placing ligatures along the intestinal tract to form independent and hermetic compartments where pathogens can be injected alone9 or with other molecules, such as vaccine candidates10,11. The pathogens of interest are placed in close contact with the intestinal cells and after a few hours of infection time, intestinal samples can be recovered for further analysis. This allows the use of multiple treatment and control groups in the same animal. Statistical analysis can be performed with repeated measures models, which increases the power of discrimination between groups and reduces the number of necessary chickens compared to oral gavage trials. Also, surgical procedures and subsequent infection times are performed under continuous general anesthesia and analgesia, hence minimizing the animal pain. Closed loop ligations are an ideal template for reducing host numbers and creating a more humane system in animal research.
Intestinal ligated loops models are well described in various species, such as calves, rabbits and mice2,9, but poorly described in chickens7. For an optimal use of this surgical model, proper technique and execution are essential for the creation of ligated intestinal loops to avoid damages to the intestinal integrity. The goal of this manuscript is to describe a step by step method in the creation of multiple intestinal loops in a chicken model. This technique is limited by the surgeon&#39;s skill and experience, as accurate procedures are essential for the success of the project.

<table>
	<tbody>
		<tr>
			<td>EZ-Scrub 747</td>
			<td>Becton Dickinson and Company</td>
			<td></td>
			<td>4% chlorhexidine gluconate detergent impregnated sterile brush. No catalog number available. Web address: https://www.bd.com/en-us/offerings/capabilities/infection-prevention/surgical-hand-scrubs/ez-scrub-preoperative-surgical-scrub-brushes&#160;</td>
		</tr>
		<tr>
			<td>Isopropyl alcohol 70% USP 4 L</td>
			<td>Commercial isopropyl alcohol</td>
			<td>P016IP70</td>
			<td>Web address: http://www.comalc.com/products/</td>
		</tr>
		<tr>
			<td>Chlorexidine</td>
			<td>Sigma-Aldrich</td>
			<td>282227-1G</td>
			<td>Chlorhexidine gluconate solution, must be diluted to 4%. Web address: http://www.sigmaaldrich.com/catalog/product/aldrich/282227?lang=fr&#38;region=CA&#38;gclid=EAIaIQobChMI8vHr4_OY1wIV3rrACh2ZWQKuEAAYAiAAEgLKx_D_BwE</td>
		</tr>
		<tr>
			<td>Surgical Drape Small (27 inch x 24 inch) with 3 x 6 inch Fenestration</td>
			<td>Veterinary Specialty Products</td>
			<td>32724</td>
			<td>Web address: http://www.vetspecialtyproducts.com/index.cfm?fuseaction=ecommercecatalog.detail&#38;productgroup_id=15</td>
		</tr>
		<tr>
			<td>Scalpel blades #3</td>
			<td>Swann-Morton</td>
			<td>301</td>
			<td>Web address: https://www.swann-morton.com/product/16.php</td>
		</tr>
		<tr>
			<td>Sterile saline NaCl 0.9%</td>
			<td>Sigma-Aldrich</td>
			<td>S8776-100ML</td>
			<td>Web address: http://www.sigmaaldrich.com/catalog/product/sigma/s8776?lang=fr&#38;region=CA</td>
		</tr>
		<tr>
			<td>Vicryl 3-0</td>
			<td>Ethicon</td>
			<td>D9003</td>
			<td>Polyglactin multifilament absorbable suture material. Web address: http://www.ethicon.com/healthcare-professionals/products/wound-closure/absorbable-sutures/coated-vicryl-polyglactin-910-suture</td>
		</tr>
		<tr>
			<td>Syringe 1 ml with 26G needle</td>
			<td>Becton Dickinson and Company</td>
			<td>329652</td>
			<td>Web address: https://www.bd.com/en-us/offerings/capabilities/diabetes-care/insulin-syringes/bd-1-ml-conventional-insulin-syringes</td>
		</tr>
		<tr>
			<td>Brain Heart Infusion</td>
			<td>Sigma-Aldrich</td>
			<td>1104930500</td>
			<td>Web address: http://www.sigmaaldrich.com/catalog/product/mm/110493?lang=fr&#38;region=CA&#38;cm_sp=Insite-_-prodRecCold_xorders-_-prodRecCold2-1</td>
		</tr>
		<tr>
			<td>Eppendorf tube</td>
			<td>Sigma-Aldrich</td>
			<td>T9661-500EA</td>
			<td>Microcentrifuge tube. Web address: http://www.sigmaaldrich.com/catalog/product/sigma/t9661?lang=fr&#38;region=CA&#38;gclid=EAIaIQobChMI-YizzfiY1wIVRkCGCh30SQjuEAAYAiAAEgLK5fD_BwE</td>
		</tr>
		<tr>
			<td>Formalin solution, buffered neutral, 10%</td>
			<td>Sigma-Aldrich</td>
			<td>HT501128-4L</td>
			<td>Ratio tissue : formalin of 1: 10 for adequate fixation. Web address: http://www.sigmaaldrich.com/catalog/product/sigma/ht501128?lang=fr&#38;region=CA</td>
		</tr>
		<tr>
			<td>Clostridium perfringens strains</td>
			<td>Universit&#233; de Montr&#233;al, Chaire en recherche avicole</td>
			<td>N/A</td>
			<td>Specific to each laboratory, available upon request to correspondant author</td>
		</tr>
	</tbody>
</table>

a ligated intestinal loop model in anesthetized specific pathogen free chickens to study clostridium perfringens virulence

Necrotic enteritis was studied in chickens using various in vivo infection models. Most of these use a combination of predisposing factors, such as coccidiosis and diet, with gavage or administration via the feed using Clostridium perfringens. In these models, the comparison of multiple C. perfringens strains for virulence studies requires a large number of hosts to obtain significant results. Mortality during the course of the study can be high depending on the experimental model, hence raising ethical concerns regarding animal welfare in research. The development of new infection models requiring fewer animals to study pathogenesis, yet providing statistically significant and valid results, is important in reducing animal use in research. Intestinal ligated loop models have been used to study clostridial infections in various species such as mice, rabbits and calves. Following surgical procedures to create ligated loop segments, C. perfringens strains are injected directly into the loops to establish a close contact between the bacteria and the intestinal mucosa. Samples of the small intestine and luminal contents are taken at the termination of the procedures after a few hours. Multiple bacterial strains can be inoculated in each animal, hence reducing the number of required subjects in the experiments. Also, procedures are performed under general anesthesia to reduce animal pain. In chickens, this model would be more appropriate than oral administration to compare C. perfringens strain pathogenicity because fewer animals are needed, no predisposing factors are required to induce the disease, and pain is controlled by analgesics. The intestinal ligated loop model is poorly described in chickens and standardization is essential for its optimal use. This manuscript provides all the necessary steps to create numerous intestinal ligated loops in chickens and brings information on the critical points to obtain valid results.

A schematic of the 9 intestinal loops and 8 interloops is shown in Figure 1. In this model, a total of 9 loops and 8 interloops are created with simple ligatures. A loop consists of proximal and distal ligatures spaced by 2 cm measured from the proximal ligature. Two adjacent loops are separated by an interloop of 1 cm. To decrease the possible risk of cross-contamination between loops by leakage from a ligature, an interloop ligature is placed mid-way from t...

Watch this Scientific Journal Video about A Ligated Intestinal Loop Model in Anesthetized Specific Pathogen Free Chickens to Study Clostridium Perfringens Virulence at JoVE.com

A Ligated Intestinal Loop Model in Anesthetized Specific Pathogen Free Chickens to Study Clostridium Perfringens Virulence

Here we present a protocol to surgically create &#39;intestinal ligated loops&#39; in chicken small intestines. This procedure allows for the comparison of multiple Clostridium perfringens strains&#39; virulence in situ in a single host. This method markedly decreases the number of chickens usually necessary for similar in vivo experiments.

A Ligated Intestinal Loop Model in Anesthetized Specific Pathogen Free Chickens to Study Clostridium Perfringens Virulence

Necrotic enteritis was studied in chickens using various in vivo infection models. Most of these use a combination of predisposing factors, such as ...

This method can help answer key questions in the field of Chicken Necrotic Enteritis research. Such as comparing the virulence of specific Clostridium perfringens strains causing this disease. The main advantage of this technique is that it remarkably reduces the number of chickens usually necessary for similar ambivore experiments.While this method can provide insight into virulence potential of Clostridium perfringens strains, it can also be applied to other intestinal pathogens such as Clostridium difficile, or Salmonella enterica. Generally, individuals new to this method will struggle because surgical procedures needs specific training and shall only be performed by those who have acquired skills such as suturing, an techniques prior to the experiment. After anesthesizing a 10 week old specific pathogen free leghorn chicken, set up the monitors for vital measurements and start manually removing the feathers from the abdomen by gentle traction.Next, scrub the surgical site using Chlorhexidine gluconate with a soft bristle brush. Gently scrub the skin from the center to the periphery for five minutes without reversing course. Then, perform three alternating passages on the surgical site with Chlorhexidine gluconate solution and Isopropyl alcohol using sterile gauzes.Again, go from the center to the periphery, then, drape the chicken. Begin by opening the drape above the surgical site, then make an L-shaped low midline skin incision with a number three scalpel, starting one centimeter cuddle to the sternum, and ending at one centimeter cranial to the cloicha. Next, continue the L-shaped incision perpendicular to the first by doing a second incision starting at the cuddle end of the first incision and continue five centimeters to the left side of the abdomen by following the pelvis line.This opening will allow easy extraction of the intestines. Next, open the peritoneum and abdominal muscles using the same L-shaped pattern to access the abdominal cavity. The air sacs will now be exposed and must be kept moist using saline soaked gauze.Next, insert a Snook spay hook into the abdominal cavity by following the left abdominal wall and working the hook around the abdominal air sacs to extract the intestines. Then, using dry gauze, continue gently exteriorizing the intestines to expose the Jejunum. Spread out the intestines and keep them moist with frequent spraying with Saline and by covering them with Saline soaked gauze.It is important to be very gentle while taking out intestines because excessive tension can rupture the mesenteric vessels which may lead to intestinal ischemic lesions and greatly compromise the outcome of the procedure. After exteriorizing the intestines, make a series of loops in the intestines beginning in the Jejunum. Each loop can be used for different treatment.In the proximal Jejunum, place a simple ligature with a Polyglutamine Multifilament synthetic absorbable material while avoiding the ligature of major mesenteric vessels. Next, place a distal ligature two centimeters away from the proximal ligature to complete the first loop. All proximal and distal ligatures should be spaced by about two centimeters.Each pair of ligatures makes a loop, which is a hermetic segment. Next, create an interloop or a segment of intestine between the loops. Place a simple ligature half a centimeter aborely to the distal ligature of the first loop.This ligature is at the middle of the interloop and will decrease possible cross contamination between loops. Now, continue the pattern of creating another loop half a centimeter aborely from the interloop ligature. Here, nine loops and eight interloops are created covering 26 centimeters of intestine.The number of loops can be adjusted as needed. Next, proceed with injecting strain of Clostridium perfringens into the loops. Into the anti-mesenteric side of the loop, use a 26 gauge needle at a 45 degree angle to inject 0.2 milliliters of BHI solution, containing one million colony forming units of bacteria in the midlog growth phase.In this situation, with nine loops, five different strains are injected in alternating loops with the intervening loops injected with vehicle alone as negative controls. After injecting the pathogens, gently replace the intestinal tract to the dorsal area of the abdominal cavity underneath the air sacs. Then, close the abdominal cavity.Suture the peritoneum and abdominal muscles along the pelvis with a simple continuous suture pattern using a Polyglutamine Multifilament synthetic absorbable material. Continue by suturing the peritoneum and abdominal muscles from the sternum to the cloiche using simple continuous sutures. Next, suture the skin close using a Polyglutamine Multifilament synthetic material and a simple continuous pattern.First, suture along the pelvis, then suture from the sternum to the cloiche. After closing the incisions, keep the chicken under general anesthesia with proper use of analgesics to minimize animal pain during the infection time. Continue anesthetic monitoring to ensure an adequate anesthesia level.After the desired amount of infection time, such as seven hours in the present experiment, euthanize the bird and collect the intestinal tissues. Using a number three scalpel, cut out a half to one centimeter loop section. Then, transfer the section to 10%Formalin for overnight fixation and further histopathological analysis.Then, use the same scalpel blade on the same loop to cut out the remainder of the loop and transfer that tissue to a microfused tube for isolation of the bacteria. Repeat this procedure for each loop using a new scalpel blade each time. Seven hours after injection, an intestinal loop injected with a control sterile medium has an intact mucosal brush border with no necrosis.Mild congestion in the intestinal layers of the segments is not uncommon. Seven hours following injection with the pathogen, Clostridium perfringens, villi tips are eroded with necrotic entry sites surrounding the tips. And then necrotic material surrounding the villi, there are clusters of large rod shaped bacteria.Sometimes necrosis is due to poor procedural execution and can be misinterpreted as lesions produced by bacteria. A telltale signs is the absence of bacteria in the histological section. Also, the blood vessels in the muscular layer are severely dilated by the accumulation of many degenerating erythrocytes indicative of vascular congestion.This was caused by ligated mesenteric blood vessels that likely were ligated to do excessive physical strain on the intestines. Ischemic loops can be easily identified microscopically during the surgical procedures. Following severe vascular congestion a few minutes after the ligature, the serosa will be dark blue instead of its normal pink reddish coloration.After watching this video, you should have a good understanding of how to create multiple intestinal loops in a chicken model by placing ligatures on the intestines. Once mastered the surgical procedures, excluding infection time, can be done in less than three hours, if it is performed properly. While attempting this procedure, it is important to remember to keep the chicken under deep anesthesia to control the pain and monitor vital signs during all the procedures, including surgical part and following infection time.Following this procedure or their methods like bacterial isolation, and straight identification such as gene detection by PCR can be performed in order to answer external questions like recovery and identification of the initial injected pathogen. After this development, this technique paved a way for researchers in the field of Clostridium perfringens pathogenesis to explore Necrotic Enteritis in chickens. Don't forget that working with live animals can be extremely variable.And precautions such as continuous anesthetic monitoring of the chicken should always be done while performing this procedure.

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Research

JoVE Journal

Medicine

Biomarkers in an Animal Model for Revealing Neural, Hematologic, and Behavioral Correlates of PTSD

Identification of biomarkers representing the evolution of the pathophysiology of Post Traumatic Stress Disorder (PTSD) is vitally important, not only for objective diagnosis but also for the evaluation of therapeutic efficacy and resilience to trauma. Ongoing research is directed at identifying molecular biomarkers for PTSD, including traumatic stress induced proteins, transcriptomes, genomic variances and genetic modulators, using biologic samples from subjects' blood, saliva, urine, and postmortem brain tissues. However, the correlation of these biomarker molecules in peripheral or postmortem samples to altered brain functions associated with psychiatric symptoms in PTSD remains unresolved. Here, we present an animal model of PTSD in which both peripheral blood and central brain biomarkers, as well as behavioral phenotype, can be collected and measured, thus providing the needed correlation of the central biomarkers of PTSD, which are mechanistic and pathognomonic but cannot be collected from people, with the peripheral biomarkers and behavioral phenotypes, which can.
Our animal model of PTSD employs restraint and tail shocks repeated for three continuous days - the inescapable tail-shock model (ITS) in rats. This ITS model mimics the pathophysiology of PTSD 17, 7, 4, 10. We and others have verified that the ITS model induces behavioral and neurobiological alterations similar to those found in PTSD subjects 17, 7, 10, 9. Specifically, these stressed rats exhibit (1) a delayed and exaggerated startle response appearing several days after stressor cessation, which given the compressed time scale of the rat's life compared to a humans, corresponds to the one to three months delay of symptoms in PTSD patients (DSM-IV-TR PTSD Criterian D/E 13), (2) enhanced plasma corticosterone (CORT) for several days, indicating compromise of the hypothalamopituitary axis (HPA), and (3) retarded body weight gain after stressor cessation, indicating dysfunction of metabolic regulation.
The experimental paradigms employed for this model are: (1) a learned helplessness paradigm in the rat assayed by measurement of acoustic startle response (ASR) and a charting of body mass; (2) microdissection of the rat brain into regions and nuclei; (3) enzyme-linked immunosorbent assay (ELISA) for blood levels of CORT; (4) a gene expression microarray plus related bioinformatics tools 18. This microarray, dubbed rMNChip, focuses on mitochondrial and mitochondria-related nuclear genes in the rat so as to specifically address the neuronal bioenergetics hypothesized to be involved in PTSD.

We describe a rat model of post traumatic stress disorder (PTSD) that reveals the persistent alterations in neuroendocrine function and the delayed long-term, exaggerated fear response, characteristic of PTSD patients. The animal model and methods described here are useful for correlating biomarkers in brain nuclei, which are mechanistic but cannot be measured in patients, with biomarkers in peripheral white blood cells, which can.

Identification of biomarkers representing the evolution of the pathophysiology of Post Traumatic Stress Disorder (PTSD) is vitally important, not only for ...

Functional Assessment of Intestinal Motility and Gut Wall Inflammation in Rodents: Analyses in a Standardized Model of Intestinal Manipulation

Inflammation of the gastrointestinal tract is a common reason for a variety of human diseases. Animal research models are critical in investigating the complex cellular and molecular of intestinal pathology. Although the tunica mucosa is often the organ of interest in many inflammatory diseases, recent works demonstrated that the muscularis externa (ME) is also a highly immunocompetent organ that harbours a dense network of resident immunocytes.1,2 These works were performed within the standardized model of intestinal manipulation (IM) that leads to inflammation of the bowel wall, mainly limited to the ME. Clinically this inflammation leads to prolonged intestinal dysmotility, known as postoperative ileus (POI) which is a frequent and unavoidable complication after abdominal surgery.3 The inflammation is characterized by liberation of proinflammatory mediators such as IL-64 or IL-1&beta; or inhibitory neurotransmitters like nitric oxide (NO).5 Subsequently, tremendous numbers of immunocytes extravasate into the ME, dominated by polymorphonuclear neutrophils (PMN) and monocytes and finally maintain POI.2 Lasting for days, this intestinal paralysis leads to an increased risk of aspiration, bacterial translocation and infectious complications up to sepsis and multi organ failure and causes a high economic burden.6
In this manuscript we demonstrate the standardized model of IM and in vivo assessment of gastrointestinal transit (GIT) and colonic transit. Furthermore we demonstrate a method for separation of the ME from the tunica mucosa followed by immunological analysis, which is crucial to distinguish between the inflammatory responses in these both highly immunoactive bowel wall compartments. All analyses are easily transferable to any other research models, affecting gastrointestinal function.

Postoperative ileus (POI) is a complication of abdominal surgery leading to increased morbidity and a prolonged hospital stay. Because prophylactic or therapeutic strategies are lacking intensified research is necessary. Therefore we established a standardized and feasible mouse model to investigate the pathophysiology of POI and to study potential therapeutic options.

Inflammation of the gastrointestinal tract is a common reason for a variety of human diseases. Animal research models are critical in investigating the ...

A Human Ex Vivo Atherosclerotic Plaque Model to Study Lesion Biology

Atherosclerosis is a chronic inflammatory disease of the vasculature. There are various methods to study the inflammatory compound in atherosclerotic lesions. Mouse models are an important tool to investigate inflammatory processes in atherogenesis, but these models suffer from the phenotypic and functional differences between the murine and human immune system. In vitro cell experiments are used to specifically evaluate cell type-dependent changes caused by a substance of interest, but culture-dependent variations and the inability to analyze the influence of specific molecules in the context of the inflammatory compound in atherosclerotic lesions limit the impact of the results. In addition, measuring levels of a molecule of interest in human blood helps to further investigate its clinical relevance, but this represents systemic and not local inflammation. Therefore, we here describe a plaque culture model to study human atherosclerotic lesion biology ex vivo. In short, fresh plaques are obtained from patients undergoing endarterectomy or coronary artery bypass grafting and stored in RPMI medium on ice until usage. The specimens are cut into small pieces followed by random distribution into a 48-well plate, containing RPMI medium in addition to a substance of interest such as cytokines or chemokines alone or in combination for defined periods of time. After incubation, the plaque pieces can be shock frozen for mRNA isolation, embedded in Paraffin or OCT for immunohistochemistry staining or smashed and lysed for western blotting. Furthermore, cells may be isolated from the plaque for flow cytometry analysis. In addition, supernatants can be collected for protein measurement by ELISA. In conclusion, the presented ex vivo model opens the possibility to further study inflammatory lesional biology, which may result in identification of novel disease mechanisms and therapeutic targets.

A Human Ex Vivo Atherosclerotic Plaque Model to Study Lesion Biology

Atherosclerosis is a chronic inflammatory process. This manuscript illustrates an easy to use ex vivo model to investigate fresh carotid or coronary artery plaques. The ex vivo model allows for the investigation of potential substances on the inflammatory milieu in human atherosclerotic lesions and results can be analyzed by various methods.

Atherosclerosis is a chronic inflammatory disease of the vasculature. There are various methods to study the inflammatory compound in atherosclerotic ...

Facial Nerve Axotomy in Mice: A Model to Study Motoneuron Response to Injury

The goal of this surgical protocol is to expose the facial nerve, which innervates the facial musculature, at its exit from the stylomastoid foramen and either cut or crush it to induce peripheral nerve injury. Advantages of this surgery are its simplicity, high reproducibility, and the lack of effect on vital functions or mobility from the subsequent facial paralysis, thus resulting in a relatively mild surgical outcome compared to other nerve injury models. A major advantage of using a cranial nerve injury model is that the motoneurons reside in a relatively homogenous population in the facial motor nucleus in the pons, simplifying the study of the motoneuron cell bodies. Because of the symmetrical nature of facial nerve innervation and the lack of crosstalk between the facial motor nuclei, the operation can be performed unilaterally with the unaxotomized side serving as a paired internal control. A variety of analyses can be performed postoperatively to assess the physiologic response, details of which are beyond the scope of this article. For example, recovery of muscle function can serve as a behavioral marker for reinnervation, or the motoneurons can be quantified to measure cell survival. Additionally, the motoneurons can be accurately captured using laser microdissection for molecular analysis. Because the facial nerve axotomy is minimally invasive and well tolerated, it can be utilized on a wide variety of genetically modified mice. Also, this surgery model can be used to analyze the effectiveness of peripheral nerve injury treatments. Facial nerve injury provides a means for investigating not only motoneurons, but also the responses of the central and peripheral glial microenvironment, immune system, and target musculature. The facial nerve injury model is a widely accepted peripheral nerve injury model that serves as a powerful tool for studying nerve injury and regeneration.

We present a surgical protocol detailing how to perform a cut or crush axotomy on the facial nerve in the mouse. The facial nerve axotomy can be employed to study the physiological response to nerve injury and test therapeutic techniques.

The goal of this surgical protocol is to expose the facial nerve, which innervates the facial musculature, at its exit from the stylomastoid foramen and ...

Vein Interposition Model: A Suitable Model to Study Bypass Graft Patency

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. Research models for bypass graft failure are essential for a better understanding of pathobiological and pathophysiological processes during graft patency loss. Large animal models, such as pigs or sheep, resemble human anatomical structures but require special facilities and equipment. This video describes a rat vein interposition model to investigate vein graft patency loss. Rats are inexpensive and easy to handle. Compared to mouse models, the convenient size of rats permits better operability and enables a sufficient amount of material to be obtained for further diverse analysis. In brief, the inferior epigastric vein of a donor rat is harvested and used to replace a segment of the femoral artery. Anastomosis is conducted via single stitches and sealed with fibrin glue. Graft patency can be monitored non-invasively using duplex sonography. Myointimal hyperplasia, which is the main cause for graft patency loss, develops progressively over time and can be calculated from histological cross sections.

This video demonstrates a model to study the development of myointimal hyperplasia after venous interposition surgery in rats.

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. ...

A Model of Free Tissue Transfer: The Rat Epigastric Free Flap

Free tissue transfer has been increasingly used in clinical practice since the 1970s, allowing reconstruction of complex and otherwise untreatable defects resulting from tumor extirpation, trauma, infections, malformations or burns. Free flaps are particularly useful for reconstructing highly complex anatomical regions, like those of the head and neck, the hand, the foot and the perineum. Moreover, basic and translational research in the area of free tissue transfer is of great clinical potential. Notwithstanding, surgical trainees and researchers are frequently deterred from using microsurgical models of tissue transfer, due to lack of information regarding the technical aspects involved in the operative procedures. The aim of this paper is to present the steps required to transfer a fasciocutaneous epigastric free flap to the neck in the rat.
This flap is based on the superficial epigastric artery and vein, which originates from and drain into the femoral artery and vein, respectively. On average the caliber of the superficial epigastric vein is 0.6 to 0.8 mm, contrasting with the 0.3 to 0.5 mm of the superficial epigastric artery. Histologically, the flap is a composite block of tissues, containing skin (epidermis and dermis), a layer of fat tissue (panniculus adiposus), a layer of striated muscle (panniculus carnosus), and a layer of loose areolar tissue.
Succinctly, the epigastric flap is raised on its pedicle vessels that are then anastomosed to the external jugular vein and to the carotid artery on the ventral surface of the rat's neck. According to our experience, this model guarantees the complete survival of approximately 70 to 80% of epigastric flaps transferred to the neck region. The flap can be evaluated whenever needed by visual inspection. Hence, the authors believe this is a good experimental model for microsurgical research and training.

This paper describes the steps required to raise a fasciocutaneous epigastric free flap and transfer it to the neck in the rat.

Free tissue transfer has been increasingly used in clinical practice since the 1970s, allowing reconstruction of complex and otherwise untreatable defects ...

Intestinal Stem Cell Isolation and Culture in a Porcine Model of Segmental Small Intestinal Ischemia

Intestinal ischemia remains a major cause of morbidity and mortality in human and veterinary patients. Many disease processes result in intestinal ischemia, when the blood supply and therefore oxygen is decreased to the intestine. This leads to intestinal barrier loss and damage to the underlying tissue. Intestinal stem cells reside at the base of the crypts of Lieberk&#252;hn and are responsible for intestinal renewal during homeostasis and following injury. Ex vivo cell culture techniques have allowed for the successful study of epithelial stem cell interactions by establishing culture conditions that support the growth of three-dimensional epithelial organ-like systems (termed "enteroids" and "colonoids" from the small and large intestine, respectively). These enteroids are composed of crypt and villus-like domains and mature to contain all of the cell types found within the epithelium. Historically, murine models have been utilized to study intestinal injury. However, a porcine model offers several advantages including similarity of size as well as gastrointestinal anatomy and physiology to that of humans. By utilizing a porcine model, we establish a protocol in which segmental loops of intestinal ischemia can be created within a single animal, enabling the study of differing time points of ischemic injury and repair in vivo. Additionally, we describe a method to isolate and culture the intestinal stem cells from the ischemic loops of intestine, allowing for the continued study of epithelial repair, modulated by stem cells, ex vivo.

This protocol will enable readers to successfully establish a porcine model of segmental intestinal ischemia and subsequently isolate and culture intestinal stem cells for the study of epithelial repair following injury.

Intestinal ischemia remains a major cause of morbidity and mortality in human and veterinary patients. Many disease processes result in intestinal ...

Isometric Contractility Measurement of the Mouse Mesenteric Artery Using Wire Myography

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and drugs. It is widely used in many studies on the physiological functions of vascular smooth muscle, the pathogenesis of vascular diseases such as hypertension, and the development of smooth muscle relaxant drugs. The mouse is a widely used model animal with a large pool of disease models and genetically modified strains. We introduced this method to measure the isometric contraction of mouse mesenteric artery in detail. A 1.4-mm segment of mouse mesenteric resistance artery was isolated and mounted on a myograph chamber by passing two steel wires through its lumen. After equilibration and normalization steps, the vessel segment was potentiated by a high-K+ solution twice prior to the contraction assay. As an example of the application of this method in drug development, we measured the relaxant effect of a novel natural substance, neoliensinine, isolated from a Chinese herb, embryos of the lotus seed (Nelumbo nucifera Gaertn.) on mouse mesenteric arteries. The vessel segments mounted on the myograph chamber were stimulated with a high-K+ solution. When the force tension reached a stable sustained phase, cumulative doses of neoliensinine were added to the chamber. We found that neoliensinine had a dose-dependent relaxant effect on smooth muscle contraction, thus suggesting that it bears potential activity against hypertension. In addition, as the vessel segment can survive at least 4 hours after mounting and maintain contractility induced by the high-K+ solution for many times, we suggest that the wire myograph system may be used for the time-consuming process of drug screening.

The wire myograph technique is used to investigate vascular smooth muscle functions and screen new drugs. We report a detailed protocol for measuring the isometric contractility of the mouse mesenteric artery and for screening new relaxants of vascular smooth muscle.

The wire myograph technique is used to assess the contractility of vascular smooth muscles in response to depolarization, GPCR agonists/inhibitors and ...

A Cryoinjury Model to Study Myocardial Infarction in the Mouse

The use of animal models is essential for developing new therapeutic strategies for acute coronary syndrome and its complications. In this article, we demonstrate a murine cryoinjury infarct model that generates precise infarct sizes with high reproducibility and replicability. In brief, after intubation and sternotomy of the animal, the heart is lifted from the thorax. The probe of a handheld liquid nitrogen delivery system is applied onto the myocardial wall to induce cryoinjury. Impaired ventricular function and electrical conduction can be monitored with echocardiography or optical mapping. Transmural myocardial remodeling of the infarcted area is characterized by collagen deposition and loss of cardiomyocytes. Compared to other models (e.g., LAD-ligation), this model utilizes a handheld liquid nitrogen delivery system to generate more uniform infarct sizes.

This article demonstrates a model to study cardiac remodeling after myocardial cryoinjury in mice.

The use of animal models is essential for developing new therapeutic strategies for acute coronary syndrome and its complications. In this article, we ...

Hemocompatibility Testing of Blood-Contacting Implants in a Flow Loop Model Mimicking Human Blood Flow

The growing use of medical devices (e.g., vascular grafts, stents, and cardiac catheters) for temporary or permanent purposes that remain in the body&#39;s circulatory system demands a reliable and multiparametric approach that evaluates the possible hematologic complications caused by these devices (i.e., activation and destruction of blood components). Comprehensive in vitro hemocompatibility testing of blood-contacting implants is the first step towards successful in vivo implementation. Therefore, extensive analysis according to the International Organization for Standardization 10993-4 (ISO 10993-4) is mandatory prior to clinical application. The presented flow loop describes a sensitive model to analyze the hemostatic performance of stents (in this case, neurovascular) and reveal adverse effects. The use of fresh human whole blood and gentle blood sampling are essential to avoid the preactivation of blood. The blood is perfused through a heparinized tubing containing the test specimen by using a peristaltic pump at a rate of 150 mL/min at 37 &#176;C for 60 min. Before and after perfusion, hematologic markers (i.e., blood cell count, hemoglobin, hematocrit, and plasmatic markers) indicating the activation of leukocytes (polymorphonuclear [PMN]-elastase), platelets (&#946;-thromboglobulin [&#946;-TG]), the coagulation system (thombin-antithrombin III [TAT]), and the complement cascade (SC5b-9) are analyzed. In conclusion, we present an essential and reliable model for extensive hemocompatibility testing of stents and other blood-contacting devices prior to clinical application.

This protocol describes a comprehensive hemocompatibility evaluation of blood-contacting devices using laser-cut neurovascular implants. A flow loop model with fresh, heparinized human blood is applied to mimic blood flow. After perfusion, various hematologic markers are analyzed and compared to the values gained directly after blood collection for hemocompatibility evaluation of the tested devices.