This research was supported by the Israel Science Foundation grants 2670/23 and 1304/20.

The experiments in the protocol were approved by&#160;the National Permit Committee - for animal science and comply with the ARVO Statement&#160;the use of animals in ophthalmic and vision research. Female Sprague-Dawley rats, aged 8-10 weeks, were used for the present study and were exposed to 12/12 h light-dark cycles. The animals were obtained from a commercial source (see Table of Materials).
1. Animal preparation
<ol>
	<li>Prepare an anesthetic mixture of ketamine (80 mg/kg body weight in 0.8 mL) and xylazine (4 mg/kg body weight in 0.2 mL) and inject it intraperitoneally in a single injection to anesthetize the rats.</li>
	<li>Inject analgesic buprenorphine (0.03 mg/kg) intraperitoneally in a single injection.</li>
	<li>Apply topical ophthalmic anesthetic 0.4% oxybuprocaine to both eyes.</li>
</ol>
2. Creating a self-sealing corneal tunnel
<ol>
	<li>Stabilize the eye by holding the superior sclera at the vertical midline next to the corneoscleral junction with surgical ophthalmic forceps.</li>
	<li>Under a surgical microscope, place a sterile 0.8 mm, 31 G stiletto blade in the paracentral corneal region in the vertical midline (above the center of the pupil) in a flat position at an angle as close as possible to horizontal (Figure 2).</li>
	<li>In this position, puncture the cornea to make an incision and create a long tunnel (2-3 mm) until it penetrates into the central area of the anterior chamber. Avoid touching the lens (Figure 2). 
	NOTE: A successful tunnel will not induce leakage of the aqueous humor and shallowing of the anterior chamber.</li>
	<li>Apply topical 0.3% ofloxacin and 0.1% dexamethasone to the injected eye.</li>
	<li>Examine under slit microscopy as follows.
	<ol>
		<li>Observe the depth of the anterior chamber of the injected eye compared to the non-injected eye. 
		NOTE: The depth should be similar.</li>
		<li>Observe the lens of the injected eye compared to the non-injected eye. 
		&#8203;NOTE: The lens should be clear. Opacity may reflect lens damage during the surgical procedure.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/66662/66662fig02.jpg" /> 
Figure 2: Schematic representation of the blade and incision angle and position. <a href="https://www.jove.com/files/ftp_upload/66662/66662fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
3. Option 1: Intracameral injection of trypan blue for assessing the successful&#160;injection into the anterior chamber
<ol>
	<li>Load 5 &#181;L of trypan blue into a sterile 10 &#181;L glass Hamilton syringe with a 34 G blunt needle. 
	NOTE: Injection of trypan blue is described as a means to evaluate the success of injection during the model calibration or setup stages. In the experimental settings, the syringe may be loaded with a solution of the compound of choice.</li>
	<li>Insert the loaded syringe needle through the tunnel created in section 2 into the anterior chamber.</li>
	<li>Inject and hold the needle in place after injection for 2-3 seconds until all fluid clears.</li>
	<li>Remove the needle by pulling it out gently and slowly to avoid leakage from the corneal tunnel.</li>
	<li>Examine under slit microscopy. Evaluate the depth of the anterior chamber to exclude shallowing and verify the presence of trypan blue in the anterior chamber.</li>
	<li>Repeat slit examination after 24 h, 48 h, and 72 h.</li>
</ol>
4. Option 2: Intracameral injection of Hoechst for assessing the bioavailability of injected material to the endothelial cell layer
<ol>
	<li>Load 5 &#181;L of Hoechst into a sterile 10 &#181;L glass Hamilton syringe with a 34 G blunt needle. 
	NOTE: Injection of Hoechst is described as a means to evaluate the bioavailability of injected material by uptake into the endothelial cell layer and is useful during the model calibration or setup stages. In the experimental settings, the syringe may be loaded with a solution of the compound of choice.</li>
	<li>Insert the loaded syringe needle through the tunnel created in section 2 into the anterior chamber.</li>
	<li>Inject and hold the needle in place after injection for 2-3 seconds until all fluid clears.</li>
	<li>Remove the needle by pulling it out gently and slowly to avoid leakage from the corneal tunnel incision.</li>
	<li>Approximately 15-20 min post-injection, euthanize the rats by intraperitoneal injection of 500 mg/kg sodium pentobarbitone.</li>
	<li>Enucleate both eyes and isolate corneas. Collect the non-injected cornea as a control.</li>
	<li>Stain both corneas with 0.5% Alizarin Red S&#160;according to manufacturer instructions to identify endothelial cells.</li>
	<li>Examine under a light microscope to image the alizarin-red staining of endothelial cells and under a fluorescent microscope to observe Hoechst staining, compared to the non-injected cornea as control.</li>
</ol>

Optimized Rat Intracameral Injection Technique for Reduced Tissue Damage

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C., 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+new+experimental+model+of+glaucoma+in+rats+through+intracameral+injections+of+hyaluronic+acid.">A new experimental model of glaucoma in rats through intracameral injections of hyaluronic acid.</a> Exp Eye Res. 81 (1), 71-80 (2005).</li><li>Belforte, N., Sande, P., de Zaval&#237;a, N., Knepper, P., Rosenstein, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+chondroitin+sulfate+on+intraocular+pressure+in+rats.">Effect of chondroitin sulfate on intraocular pressure in rats.</a> Invest Ophthalmol Vis Sci. 51 (11), 5768-5775 (2010).</li><li>Matsumoto, Y., Kanamori, A., Nakamura, M., Negi, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rat+chronic+glaucoma+model+induced+by+intracameral+injection+of+microbeads+suspended+in+sodium+sulfate-sodium+hyaluronate.">Rat chronic glaucoma model induced by intracameral injection of microbeads suspended in sodium sulfate-sodium hyaluronate.</a> Jpn J Ophthalmol. 58 (3), 290-297 (2014).</li><li>Liu, 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=A+novel+rat+model+of+ocular+hypertension+by+a+single+intracameral+injection+of+cross-linked+hyaluronic+acid+hydrogel+(Healaflow&#174;+).">A novel rat model of ocular hypertension by a single intracameral injection of cross-linked hyaluronic acid hydrogel (Healaflow&#174; ).</a> Basic Clin Pharmacol Toxicol. 127 (5), 361-370 (2020).</li><li>Bowen, R. C., 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=Comparative+analysis+of+the+safety+and+efficacy+of+intracameral+cefuroxime,+moxifloxacin+and+vancomycin+at+the+end+of+cataract+surgery:+a+meta-analysis.">Comparative analysis of the safety and efficacy of intracameral cefuroxime, moxifloxacin and vancomycin at the end of cataract surgery: a meta-analysis.</a> Br J Ophthalmol. 102 (9), 1268-1276 (2018).</li><li>Kato, 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=Prophylactic+antibiotics+for+postcataract+surgery+endophthalmitis:+a+systematic+review+and+network+meta-analysis+of+6.8+million+eyes.">Prophylactic antibiotics for postcataract surgery endophthalmitis: a systematic review and network meta-analysis of 6.8 million eyes.</a> Sci Rep. 12 (1), 17416 (2022).</li><li>Wang, M., Liu, Y., Dong, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+cefuroxime+intracameral+injection+antibiotic+prophylactic+on+postoperative+endophthalmitis+wound+post-cataract:+A+meta-analysis.">Effect of cefuroxime intracameral injection antibiotic prophylactic on postoperative endophthalmitis wound post-cataract: A meta-analysis.</a> Int Wound J. 20 (5), 1376-1383 (2023).</li><li>Katz, G., 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=Intracameral+cefuroxime+and+the+incidence+of+post-cataract+endophthalmitis:+an+Israeli+experience.">Intracameral cefuroxime and the incidence of post-cataract endophthalmitis: an Israeli experience.</a> Graefes Arch Clin Exp Ophthalmol. 253 (10), 1729-1733 (2015).</li><li>Lipnitzki, I., Ben Eliahu, S., Marcovitz, A. 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U., Tandel, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Study+of+the+effect+of+injection+bevacizumab+through+various+routes+in+neovascular+glaucoma.">Study of the effect of injection bevacizumab through various routes in neovascular glaucoma.</a> J Curr Glaucoma Pract. 10 (2), 39-48 (2016).</li><li>Al-Qaysi, Z. K., Beadham, I. G., Schwikkard, S. L., Bear, J. C., Al-Kinani, A. A., Alany, R. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sustained+release+ocular+drug+delivery+systems+for+glaucoma+therapy.">Sustained release ocular drug delivery systems for glaucoma therapy.</a> Expert Opin Drug Deliv. 20 (7), 905-919 (2023).</li><li>Eghrari, A. O., Gottsch, J. 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Marcovich A. L. holds patents in Steba Biotech, Yeda Weizmann, EyeYon Medical, and Mor Isum and is a consultant for EyeYon Medical and Johnson &#38; Johnson. All other authors have no competing interests.

Pre-clinical research models should provide a controlled and reproducible environment to ensure the reliability and applicability of findings. In ophthalmology research, eye injection models are commonly used in diverse research aspects ranging from establishing disease models, testing new treatments, and assessing tissue reactions and potential adverse effects.
Intracameral injections serve as a common technique in experimental ophthalmology, facilitating the direct delivery of compounds to t...

The bioavailability of compounds delivered by topical administration to the surface of the eye is greatly limited, typically &#60;5%1. Compounds administered by eye drops are mainly&#160;eliminated by drainage, induced lacrimation, tear fluid turnover, and conjunctival absorption. In addition, the permeation of compounds through the ocular surface is highly restricted by the cornea-conjunctiva barrier1,2,3. The cornea is composed of three main layers: the outermost epithelium, the intermediate stroma, and the innermost endothelium. The superficial corneal epithelium is interconnected by strong&#160;tight junctions and creates high paracellular resistance, which is the main barrier to substance permeability. Multiple epithelium layers further limit the permeation of hydrophilic and large molecules through the intercellular spaces of the cornea epithelium. Succeeding the epithelium, the stroma is composed of collagen fibers and contains aqueous pores. In contrast to the corneal epithelium, the stroma allows the movement of hydrophilic drugs; however, it is greatly impermeable to lipophilic compounds1,2,3. Together, the corneal epithelium and stromal layers present major tissue barriers that limit drug absorption. The corneal endothelium is not considered to restrict drug transport.
Alternative to the corneal delivery route is the conjunctival route. The conjunctiva is a multi-epithelium layer that covers the inner side of the eyelids and the anterior part of the sclera. The conjunctiva is characterized by fewer tight junctions than the corneal epithelium, allowing better permeability of hydrophilic drugs. However, vascularization of the conjunctiva results in systemic absorption of a large fraction of the administered molecules, again greatly limiting the bioavailability of delivered compounds to the anterior chamber1,2. An efficient way to bypass the outer ocular permeability barriers is to deliver the drug directly into the region of interest. For example, intravitreal injection is common for delivery into the vitreous humor4. Likewise, intracameral injection is utilized for delivery into the anterior chamber5. Establishing an efficient concentration at the anterior chamber is critical to various clinical situations, such as the treatment of infection by intracameral injection of antibiotics and postoperative anti-inflammatory treatments in cataract surgeries. Despite the advantage of improved substance bioavailability granted by intracameral injection, there are major safety concerns that should be considered. For example, intracameral drug injection may induce increased intraocular pressure, toxic anterior segment syndrome, and toxic endothelial cell destruction syndrome5,6. It is, therefore, essential to carefully assess in pre-clinical studies the efficacy and safety of drugs delivered by intracameral injections to maximize treatment efficiency and minimize potential adverse effects in patients.
Experimental animal models are indispensable in pre-clinical studies to investigate new treatments. Small rodents, such as mice and rats, are the most commonly utilized laboratory animals for such purposes. These animals exhibit numerous similarities to human anatomy and physiology, providing valuable insights. Moreover, their use is economically advantageous due to their small size, ease of maintenance, fast gestation, and ability to produce large numbers of offspring7.
Despite the widespread use of small rodents in eye disease models, their unique eye dimensions and anatomy pose significant challenges during experimental manipulations. For instance, procedures like intracameral injections, which are relatively straightforward in humans, become technically demanding in mice and rats. The challenges stem from factors such as the small volume of aqueous humor, the relatively large and inflexible lens, and the obstructive positioning and curvature of the lens within the rodents&#39; eyes (Figure 1)8. These challenges increase the risk of damage during intracameral injections in rodents, leading to potential adverse effects and introducing experimental variability that can impact the validity of study conclusions. In our research, we have successfully developed a procedure for safe intracameral injection in rats. The technique involves creating a long, flat, self-sealing tunnel in the cornea into the anterior chamber. This method not only ensures precision but also enhances experimental reproducibility, addressing the issues associated with injection techniques in small rodents.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/66662/66662fig01.jpg" /> 
Figure 1: Schematic representation of the anatomical anterior segment features of rat and human eyes. <a href="https://www.jove.com/files/ftp_upload/66662/66662fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Alizarin Red&#160;</td>
			<td>Alpha Aesar</td>
			<td>042040.5</td>
			<td></td>
		</tr>
		<tr>
			<td>Buprenorphine&#160;</td>
			<td>Richter pharma</td>
			<td>102047</td>
			<td></td>
		</tr>
		<tr>
			<td>Dexamethasone 0.1%&#160;</td>
			<td>Fisher Pharmaceutical</td>
			<td>393102-0413</td>
			<td></td>
		</tr>
		<tr>
			<td>Hamilton glass syringe 10 &#956;L&#160;</td>
			<td>Hamilton Co.</td>
			<td>721711</td>
			<td></td>
		</tr>
		<tr>
			<td>Hoeschst</td>
			<td>Merck</td>
			<td>B2261</td>
			<td></td>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td>Bremer pharma GMBH (medimarket)</td>
			<td>17889</td>
			<td></td>
		</tr>
		<tr>
			<td>Ofloxacin 0.3% eye drops</td>
			<td>Allergan</td>
			<td>E92170</td>
			<td></td>
		</tr>
		<tr>
			<td>Oxybuprocaine Hydrochloride 0.4%&#160;</td>
			<td>Fisher Pharmaceutical</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Pentobarbital sodium 200 mg/mL</td>
			<td>CTS</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Slit microscope&#160;</td>
			<td>Haag-streit bern</td>
			<td>b-90019115</td>
			<td></td>
		</tr>
		<tr>
			<td>Sprague-Dawley Rats</td>
			<td>Envigo</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Stiletto blade 31 G 0.8 mm&#160;</td>
			<td>Tecfen medical (skymed)</td>
			<td>QKN2808</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical microscope</td>
			<td>Zeiss</td>
			<td>OPMI-6 CFC</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypan Blue</td>
			<td>Sartorius</td>
			<td>03-102-1B</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>Eurovet Animal Health&#160;</td>
			<td>615648</td>
			<td></td>
		</tr>
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intracameral injection in rats with low risk of adverse effects

Intracameral injection is a standard administration routine in ophthalmology. The application of intracameral injection in rodents for research is challenging due to the limiting dimensions and anatomy of the eye, including the small aqueous humor volume, the lens curvature, and lens thickness. Potential damage during intracameral injections introduces adverse effects and experimental variability. This protocol describes a procedure for intracameral injection in rats, allowing precision and reproducibility.
Sprague-Dawley rats were used as experimental models. Since the lens position in rats protrudes into the anterior chamber, injecting from the periphery, as done in humans, is unfavorable. Therefore, an incision is created in the central corneal region using a 31 gauge 0.8 mm stiletto blade to form a self-sealing tunnel into the anterior chamber. An incision at&#160;an angle close to the flat allows to create a long tunnel, which minimizes the loss of aqueous humor and shallowing of the anterior chamber. A 34 gauge nanoneedle is inserted into the tunnel for injection. This enables penetration with minimal friction resistance and avoids touching the lens. Injection of trypan-blue allows&#160;visualization&#160;by slit microscopy the presence of the dye in the anterior chamber and exclude leakage. Bioavailability to the corneal endothelial layer is demonstrated by injection of Hoechst dye, which stained the nuclei of corneal endothelial cells after injection.
In conclusion, this protocol implements a procedure for accurate intracameral injection in rats. This procedure may be used for intracameral delivery of various drugs and compounds in experimental rat models, increasing the efficiency and reproducibility of ophthalmic research.

Sprague Dawley rats were intracamerally injected with 5 &#181;L of trypan blue according to the protocol described above. Slit lamp examination immediately after injection demonstrated that the chamber was stained with trypan blue, indicating that the injected material reached the anterior chamber (Figure 3). Furthermore, the anterior chamber depth was intact, suggesting that the injection did not cause leakage of aqueous humor and shallowing of the chamber.
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Author Spotlight: A Novel Protocol for Intracameral Injections to Enhance Precision in Rodent Ophthalmology

This protocol describes a technique for intracameral injection in rats using a central corneal incision and a long tunnel into the anterior chamber. This injection method minimizes the risk of inducing inadvertent tissue damage and thereby improves precision and reproducibility.

Intracameral Injection in Rats with Low Risk of Adverse Effects

Intracameral injection is a standard administration routine in ophthalmology. The application of intracameral injection in rodents for research is ...

intracameral-injection-in-rats-with-low-risk-of-adverse-effects

Research

JoVE Journal

Biology

600 Views.  Kaplan Medical Center. This protocol describes a technique for intracameral injection in rats using a central corneal incision and a long tunnel into the anterior chamber. This injection method minimizes the risk of inducing inadvertent tissue damage and thereby improves precision and reproducibility.

Video: Author Spotlight: A Novel Protocol for Intracameral Injections to Enhance Precision in Rodent Ophthalmology

Isolation of Mononuclear Cells from the Central Nervous System of Rats with EAE

Whether studying an autoimmune disease directed to the central nervous system (CNS), such as experimental autoimmune encephalomyelitis (EAE, 1), or the immune response to an infection of the CNS, such as poliomyelitis, Lyme neuroborreliosis, or neurosyphilis, it is often necessary to isolate the CNS-infiltrating immune cells.
In this video-protocol we demonstrate how to isolate mononuclear cells (MNCs) from the CNS of a rat with EAE. The first step of this procedure requires a cardiac perfusion of the rodent with a saline solution to ensure that no blood remains in the blood vessels irrigating the CNS. Any blood contamination will artificially increase the number of apparent CNS-infiltrating MNCs and may alter the apparent composition of the immune infiltrate. We then demonstrate how to remove the brain and spinal cord of the rat for subsequent dilaceration to prepare a single-cell suspension. This suspension is separated on a two-layer Percoll gradient to isolate the MNCs. After washing, these cells are then ready to undergo any required procedure. 
Mononuclear cells isolated using this procedure are viable and can be used for electrophysiology, flow cytometry (FACS), or biochemistry. If the technique is performed under sterile conditions (using sterile instruments in a tissue culture hood) the cells can also be grown in tissue culture medium. A given cell population can be further purified using either magnetic separation procedures or a FACS.

In this video we demonstrate how to isolate mononuclear cells from the central nervous system of rats with experimental autoimmune encephalomyelitis.

Whether studying an autoimmune disease directed to the central nervous system (CNS), such as experimental autoimmune encephalomyelitis (EAE, 1), or the ...

Retro-orbital Injection in Adult Zebrafish

Drug treatment of whole animals is an essential tool in any model system for pharmacological and chemical genetic studies. Intravenous (IV) injection is often the most effective and noninvasive form of delivery of an agent of interest. In the zebrafish (Danio rerio), IV injection of drugs has long been a challenge because of the small vessel diameter. This has also proved a significant hurdle for the injection of cells during hematopoeitic stem cell transplantation. Historically, injections into the bloodstream were done directly through the heart. However, this intra-cardiac procedure has a very high mortality rate as the heart is often punctured during injection leaving the fish prone to infection, massive blood loss or fatal organ damage. Drawing on our experience with the mouse, we have developed a new injection procedure in the zebrafish in which the injection site is behind the eye and into the retro-orbital venous sinus. This retro-orbital (RO) injection technique has been successfully employed in both the injection of drugs in the adult fish as well as transplantation of whole kidney marrow cells. RO injection has a much lower mortality rate than traditional intra-cardiac injection. Fish that are injected retro-orbitally tend to bleed less following injection and are at a much lower risk of injury to a major organ like the heart. Further, when performed properly, injected cells and/or drugs quickly enter the bloodstream allowing compounds to exert their effect on the whole fish and kidney cells to easily home to their niche. Thus, this new injection technique minimizes mortality while allowing efficient delivery of material into the bloodstream of adult fish. Here we exemplify this technique by retro-orbital injection of Tg(globin:GFP) cells into adult casper fish as well as injection of a red fluorescent dye (dextran, Texas Red ) into adult casper fish. We then visualize successful injections by whole animal fluorescence microscopy.

Here we show how to do retro-orbital injection in adult zebrafish.

Drug treatment of whole animals is an essential tool in any model system for pharmacological and chemical genetic studies. Intravenous (IV) injection is ...

Changes in Mammary Gland Morphology and Breast Cancer Risk in Rats

Studies in rodent models of breast cancer show that exposures to dietary/hormonal factors during the in utero and pubertal periods, when the mammary gland undergoes extensive modeling and re-modeling, alter susceptibility to carcinogen-induced mammary tumors. Similar findings have been described in humans: for example, high birthweight increases later risk of developing breast cancer, and dietary intake of soy during childhood decreases breast cancer risk. It is thought that these prenatal and postnatal dietary modifications induce persistent morphological changes in the mammary gland that in turn modify breast cancer risk later in life. These morphological changes likely reflect epigenetic modifications, such as changes in DNA methylation, histones and miRNA expression that then affect gene transcription . In this article we describe how changes in mammary gland morphology can predict mammary cancer risk in rats. Our protocol specifically describes how to dissect and remove the rat abdominal mammary gland and how to prepare mammary gland whole mounts. It also describes how to analyze mammary gland morphology according to three end-points (number of terminal end buds, epithelial elongation and differentiation) and to use the data to predict risk of developing mammary cancer.

Our protocol describes how to dissect the rat abdominal mammary gland and how to prepare mammary gland whole mounts. It also describes how to analyze mammary gland morphology using three end-points (number of terminal end buds, epithelial elongation and differentiation) and to use these results to predict mammary cancer risk in rats which were exposed to dietary modifications in utero or during prepuberty.

Studies in rodent models of breast cancer show that exposures to dietary/hormonal factors during the in utero and pubertal periods, when the mammary gland ...

A Noninvasive Hair Sampling Technique to Obtain High Quality DNA from Elusive Small Mammals

Noninvasive genetic sampling approaches are becoming increasingly important to study wildlife populations. A number of studies have reported using noninvasive sampling techniques to investigate population genetics and demography of wild populations1. This approach has proven to be especially useful when dealing with rare or elusive species2. While a number of these methods have been developed to sample hair, feces and other biological material from carnivores and medium-sized mammals, they have largely remained untested in elusive small mammals. In this video, we present a novel, inexpensive and noninvasive hair snare targeted at an elusive small mammal, the American pika (Ochotona princeps). We describe the general set-up of the hair snare, which consists of strips of packing tape arranged in a web-like fashion and placed along travelling routes in the pikas&#x2019; habitat. We illustrate the efficiency of the snare at collecting a large quantity of hair that can then be collected and brought back to the lab. We then demonstrate the use of the DNA IQ system (Promega) to isolate DNA and showcase the utility of this method to amplify commonly used molecular markers including nuclear microsatellites, amplified fragment length polymorphisms (AFLPs), mitochondrial sequences (800bp) as well as a molecular sexing marker. Overall, we demonstrate the utility of this novel noninvasive hair snare as a sampling technique for wildlife population biologists. We anticipate that this approach will be applicable to a variety of small mammals, opening up areas of investigation within natural populations, while minimizing impact to study organisms.

We present a noninvasive sampling approach to efficiently collect hair samples from elusive small mammals, as shown for the American pika. We demonstrate the utility of this method by extracting DNA from sampled hair and amplifying several types of molecular markers commonly used in studies of wildlife ecology and conservation.

Noninvasive genetic sampling approaches are becoming increasingly important to study wildlife populations. A number of studies have reported using ...

Quantitation of Endothelial Cell Adhesiveness In Vitro

One of the cardinal processes of inflammation is the infiltration of immune cells from the lumen of the blood vessel to the surrounding tissue. This occurs when endothelial cells, which line blood vessels, become adhesive to circulating immune cells such as monocytes. In vitro measurement of this adhesiveness has until now been done by quantifying the total number of monocytes that adhere to an endothelial layer either as a direct count or by indirect measurement of the fluorescence of adherent monocytes. While such measurements do indicate the average adhesiveness of the endothelial cell population, they are confounded by a number of factors, such as cell number, and do not reveal the proportion of endothelial cells that are actually adhesive. Here we describe and demonstrate a method which allows the enumeration of adhesive cells within a tested population of endothelial monolayer. Endothelial cells are grown on glass coverslips and following desired treatment are challenged with monocytes (that may be fluorescently labeled). After incubation, a rinsing procedure, involving multiple rounds of immersion and draining, the cells are fixed. Adhesive endothelial cells, which are surrounded by monocytes are readily identified and enumerated, giving an adhesion index that reveals the actual proportion of endothelial cells within the population that are adhesive.

Quantitation of Endothelial Cell Adhesiveness In Vitro

We report an in vitro method that allows the quantitation of the actual number of adhesive cells within an endothelial cell monolayer.

One of the cardinal processes of inflammation is the infiltration of immune cells from the lumen of the blood vessel to the surrounding tissue. This ...

Gap Junctional Intercellular Communication: A Functional Biomarker to Assess Adverse Effects of Toxicants and Toxins, and Health Benefits of Natural Products

This protocol describes a scalpel loading-fluorescent dye transfer (SL-DT) technique that measures intercellular communication through gap junction channels, which is a major intercellular process by which tissue homeostasis is maintained. Interruption of gap junctional intercellular communication (GJIC) by toxicants, toxins, drugs, etc. has been linked to numerous adverse health effects. Many genetic-based human diseases have been linked to mutations in gap junction genes. The SL-DT technique is a simple functional assay for the simultaneous assessment of GJIC in a large population of cells. The assay involves pre-loading cells with a fluorescent dye by briefly perturbing the cell membrane with a scalpel blade through a population of cells. The fluorescent dye is then allowed to traverse through gap junction channels to neighboring cells for a designated time. The assay is then terminated by the addition of formalin to the cells. The spread of the fluorescent dye through a population of cells is assessed with an epifluorescence microscope and the images are analyzed with any number of morphometric software packages that are available, including free software packages found on the public domain. This assay has also been adapted for in vivo studies using tissue slices from various organs from treated animals. Overall, the SL-DT assay can serve a broad range of in vitro pharmacological and toxicological needs, and can be potentially adapted for high throughput set-up systems with automated fluorescence microscopy imaging and analysis to elucidate more samples in a shorter time.

This protocol describes a scalpel loading-fluorescent dye transfer technique that measures intercellular communication through gap junction channels. Gap junctional intercellular communication is a major cellular process by which tissue homeostasis is maintained and disruption of this cell signaling has adverse health effects.

This protocol describes a scalpel loading-fluorescent dye transfer (SL-DT) technique that measures intercellular communication through gap junction ...

An Alternative Approach for Sample Preparation with Low Cell Number for TEM Analysis

Transmission electron microscopy (TEM) provides details of the cellular organization and ultrastructure. However, TEM analysis of rare cell populations, especially cells in suspension such as hematopoietic stem cells (HSCs), remains limited due to the requirement of a high cell number during sample preparation. There are a few cytospin or monolayer approaches for TEM analysis from scarce samples, but these approaches fail to get significant quantitative data from the limited number of cells. Here, an alternative and novel approach for sample preparation in TEM studies is described for rare cell populations that enables quantitative analysis.
A relatively low cell number, i.e., 10,000 HSCs, was successfully used for TEM analysis compared to the millions of cells typically used for TEM studies. In particular, Evans blue staining was performed after paraformaldehyde-glutaraldehyde (PFA-GA) fixation to visualize the tiny cell pellet, which facilitated embedding in agarose. Clusters of numerous cells were observed in ultra-thin sections. The cells had a well preserved morphology, and the ultra-structural details of the Golgi complex and several mitochondria were visible. This efficient, easy and reproducible protocol allows sample preparation from a low cell number and can be used for qualitative and quantitative TEM analysis on rare cell populations from limited biological samples.

Here, we present a protocol to prepare samples with low cell numbers for transmission electron microscopy (TEM) analysis.

Transmission electron microscopy (TEM) provides details of the cellular organization and ultrastructure. However, TEM analysis of rare cell populations, ...

Procedure and Key Optimization Strategies for an Automated Capillary Electrophoretic-based Immunoassay Method

New technologies that utilize capillary-based immunoassays promise faster and more quantitative protein assessment compared to traditional immunoassays. However, similar to other antibody-based protein assays, optimization of capillary-based immunoassay parameters, such as protein concentration, antibody dilution, and exposure time is an important prerequisite to the generation of meaningful and reliable data. Measurements must fall within the linear range of the assay where changes in signal are directly proportional to changes in lysate concentration. The process of choosing appropriate lysate concentrations, antibody dilutions, and exposure times in the human bronchial epithelial cell line, BEAS-2B, is demonstrated here. Assay linearity is shown over a range of whole cell extract protein concentrations with p53 and &#945;-tubulin antibodies. An example of signal burnout is seen at the highest concentrations with long exposure times, and an &#945;-tubulin antibody dilution curve is shown demonstrating saturation. In addition, example experimental results are reported for doxorubicin-treated cells using optimized parameters.

A capillary-based immunoassay using a commercial platform to measure target proteins from total protein preparations is demonstrated. In addition, assay parameters of exposure time, protein concentration, and antibody dilution are optimized for a cell culture model system.

New technologies that utilize capillary-based immunoassays promise faster and more quantitative protein assessment compared to traditional immunoassays. ...

Cystometric and External Urethral Sphincter Measurements in Awake Rats with Implanted Catheter and Electrodes Allowing for Repeated Measurements

Lower urinary tract function is mainly assessed by means of cystometric bladder function analysis in rodents. Conventional cystometries are usually performed as terminal analysis under urethane anesthesia. It is well known that anesthetic drugs can influence bladder function. Hence, the aim of this technique is to perform cystometric measurements of the urinary bladder and external urethral sphincter in lightly restrained awake rats. For this purpose, a bladder catheter is implanted into the bladder dome. Subsequently, two electrodes are implanted bilateral to the external urethral sphincter and a ground electrode is sutured to a non-responsive skeletal muscle. The bladder catheter and the three electrodes are finally tunneled subcutaneously to the neck region and affixed to a harness. With this technique, the lower urinary tract can be measured at multiple time points in the same animal to assess lower urinary tract function. The main application of this technique is the follow-up of simultaneous urinary bladder and external urethral sphincter function in awake healthy rats and after induction of a disease or injury. Moreover, subsequent lower urinary tract monitoring can be performed during evaluation of the disease/injury and to monitor treatment efficacy.

This protocol first describes the surgical procedure of the permanent implantation of a urinary bladder catheter combined with external urethral sphincter electrodes, and second, the measurement of the function of the urinary bladder and external urethral sphincter in implanted awake animals.

Lower urinary tract function is mainly assessed by means of cystometric bladder function analysis in rodents. Conventional cystometries are usually ...

Investigating the Detrimental Effects of Low Pressure Plasma Sterilization on the Survival of Bacillus subtilis Spores Using Live Cell Microscopy

Plasma sterilization is a promising alternative to conventional sterilization methods for industrial, clinical, and spaceflight purposes. Low pressure plasma (LPP) discharges contain a broad spectrum of active species, which lead to rapid microbial inactivation. To study the efficiency and mechanisms of sterilization by LPP, we use spores of the test organism Bacillus subtilis because of their extraordinary resistance against conventional sterilization procedures. We describe the production of B. subtilis spore monolayers, the sterilization process by low pressure plasma in a double inductively coupled plasma reactor, the characterization of spore morphology using scanning electron microscopy (SEM), and the analysis of germination and outgrowth of spores by live cell microscopy. A major target of plasma species is genomic material (DNA) and repair of plasma-induced DNA lesions upon spore revival is crucial for survival of the organism. Here, we study the germination capacity of spores and the role of DNA repair during spore germination and outgrowth after treatment with LPP by tracking fluorescently-labelled DNA repair proteins (RecA) with time-resolved confocal fluorescence microscopy. Treated and untreated spore monolayers are activated for germination and visualized with an inverted confocal live cell microscope over time to follow the reaction of individual spores. Our observations reveal that the fraction of germinating and outgrowing spores is dependent on the duration of LPP-treatment reaching a minimum after 120 s. RecA-YFP (yellow fluorescence protein) fluorescence was detected only in few spores and developed in all outgrowing cells with a slight elevation in LPP-treated spores. Moreover, some of the vegetative bacteria derived from LPP-treated spores showed an increase in cytoplasm and tended to lyse. The described methods for analysis of individual spores could be exemplary for the study of other aspects of spore germination and outgrowth.

Investigating the Detrimental Effects of Low Pressure Plasma Sterilization on the Survival of Bacillus subtilis Spores Using Live Cell Microscopy

This protocol illustrates the important consecutive steps required to assess the relevance of monitoring vitality parameter and DNA repair processes in reviving Bacillus subtilis spores after treatment with low pressure plasma by tracking fluorescence-labelled DNA repair proteins via time-resolved confocal microscopy and scanning electron microscopy.

Plasma sterilization is a promising alternative to conventional sterilization methods for industrial, clinical, and spaceflight purposes. Low pressure ...