This work was funded by National Funds through FCT-Funda&#231;&#227;o para a Ci&#234;ncia e a Tecnologia, I.P., under the project UIDB/04293/2020.

C57BL/6 mice were commercially purchased and hepcidin-null (Hamp1&#8722;/&#8722;) mice on a C57BL/6 background8 were a kind gift from Sophie Vaulont (Institut Cochin, France). Animals were housed at the i3S animal facility under specific pathogen-free conditions, in a temperature- and light-controlled environment, with free access to standard rodent chow and water. European sea bass (Dicentrarchus labrax) were purchased from a commercial fish farm and housed at the ICBAS animal facility, in a temperature- and light-controlled environment, and fed daily ad libitum with standard sea bass feed. All procedures involving vertebrate animals were approved by the i3S Animal Ethics Committee and the national authority, Dire&#231;&#227;o-Geral de Alimenta&#231;&#227;o e Veterin&#225;ria (DGAV). Information about commercial reagents, equipment, and animals is listed in the Table of Materials.
1. Solution preparation
NOTE: Handle and prepare all reagents and solutions with iron-free glassware or disposable plasticware. Do not allow metallic laboratory materials (e.g., stainless steel spatulas) to come in contact with any reagent or solution, due to the risk of iron contamination. Make sure any reusable glassware is iron-free. Wash the materials with appropriate laboratory detergent for 30-60 min, rinse with deionized water, soak overnight in a 37% nitric acid solution diluted 1:3 with deionized water, rinse again with deionized water, and allow to dry.
<ol>
	<li>Acid mixture: Add 10 g of trichloroacetic acid to 82.2 mL of 37% hydrochloric acid in a glass bottle, thoroughly dissolve, and adjust the final volume to 100 mL with deionized water. Shake before use. Alternatively, use only 37% hydrochloric acid for tissue digestion. 
	NOTE: The solution is stable for at least 2 months when stored in dark brown glass reagent bottles. 
	CAUTION: Hydrochloric acid and trichloroacetic acid are corrosive, and concentrated forms release toxic acidic vapors. Wear protective garments, chemical-resistant gloves, and chemical splash goggles at all times when handling acids. Avoid breathing them in and always handle acids while under a fume hood.</li>
	<li>Saturated sodium acetate: Add 228 g of anhydrous sodium acetate to 400 mL of deionized water in a glass bottle and agitate overnight at room temperature. Let the solution rest and precipitate for a day. If no precipitation occurs, continue adding small amounts of sodium acetate. Store the solution in a glass bottle.</li>
	<li>Chromogen Reagent: To prepare 1 mL of chromogen reagent, add 1 mg of 4,7-diphenyl-1,10-phenanthroline disulfonic acid disodium salt to 500 &#181;L of deionized water and 10 &#181;L of concentrated (100%) thioglycolic acid, and thoroughly dissolve. Make up the final volume to 1 mL with deionized water. 
	NOTE: Prepare as much chromogen reagent as needed. The solution is stable for 1 month when protected from light.</li>
	<li>Working Chromogen Reagent (WCR): Add 1 volume of the Chromogen Reagent to 5 volumes of saturated sodium acetate and 5 volumes of deionized water. 
	NOTE: This solution should be prepared freshly on the day of use.</li>
	<li>Stock Iron Standard Solution: To prepare a 20 mM stock iron solution, place 111.5 mg of carbonyl iron powder in a 250 mL volumetric flask containing 5,480 &#181;L of 37% hydrochloric acid. Leave to dissolve overnight at room temperature (or incubate in a boiling water bath). Then, make up the solution to a final volume of 100 mL with deionized water. 
	NOTE: The standard solution can be kept indefinitely when stored in a tightly sealed vessel.</li>
	<li>Working Iron Standard Solution (WISS): Add 13.5 &#181;L of 37% hydrochloric acid to 500 &#181;L of deionized water. Add 10 &#181;L of the Stock Iron Standard Solution and make up the final volume to 1 mL with deionized water (11.169 &#181;g of Fe/mL, 200 &#181;M; measured by AAS). 
	&#8203;NOTE: The working solution should be prepared freshly on the day of use.</li>
</ol>
2. Sample drying
<ol>
	<li>Cut a sample of tissue weighing 10-100 mg with a scalpel blade. Weigh it accurately in an analytical/precision balance over a small piece of parafilm (Fresh Weight).</li>
	<li>Using plastic tweezers, place the piece of tissue in a 24-well plate (unlidded to allow for water evaporation) and let it dry on a standard incubator at 65 &#176;C for 48 h.</li>
	<li>Alternatively, use a laboratory microwave digestion oven for drying tissue samples. Using plastic tweezers, place the weighed piece of tissue in an iron-free Teflon cup and dry it in the microwave. Set the operating parameters according to the instrument&#39;s instructions manual. 
	NOTE: As a reference, operating parameters for drying liver samples using the specific digestion oven (see Table of Materials) are shown in Table 1.</li>
	<li>Using plastic tweezers, place each dried piece of tissue over a small piece of parafilm inside an analytical/precision balance and weigh it accurately (Dry Weight).</li>
</ol>
3. Sample acidic digestion
<ol>
	<li>Using plastic tweezers, transfer each dried piece of tissue into a 1.5 mL microcentrifuge tube.</li>
	<li>Add 1 mL of the acid mixture and close the microcentrifuge tube. Prepare an acid blank in the same way, except that the tissue is omitted. 
	CAUTION: The acid mixture is corrosive and releases toxic vapors. Wear protective garments, chemical-resistant gloves, and chemical splash goggles when handling the acid mixture. Avoid breathing it in and always handle it while under a fume hood.</li>
	<li>Digest the tissues by incubating the microcentrifuge tubes in an incubator at 65 &#176;C for 20 h.</li>
	<li>After cooling to room temperature, transfer 500 &#181;L of the clear (yellow) acid extract (supernatant) into a new 1.5 mL microcentrifuge tube using a micropipette fitted with plastic tips. If it is not possible to obtain a clear supernatant, perform a short centrifugation spin. 
	CAUTION: The supernatant is highly acidic. Wear protective garments, chemical-resistant gloves, and chemical splash goggles when handling the supernatants. Always handle them while under a fume hood. 
	&#8203;NOTE: At this point, the acid extracts can be immediately used for the colorimetric assay or frozen at -20 &#176;C for later use. Completely thaw frozen samples to room temperature and vortex them prior to use.</li>
</ol>
4. Color development
<ol>
	<li>Prepare chromogen reactions as indicated in Table 2 in 1.5 mL microcentrifuge tubes or, for higher throughput, directly into the flat bottom, 96-well, clear, untreated polystyrene microplates. Prepare all reactions (acid blank, standard, and sample) at least in duplicate.</li>
	<li>Incubate at room temperature for 15 min.</li>
</ol>
5. Absorbance reading
<ol>
	<li>Measure sample absorbance in a spectrophotometer or plate reader at a wavelength of 535 nm against a deionized water reference. Plates can be read unlidded or lidded. In the lidded case, remove any condensation formed due to the release of acid vapors from the lid just prior to the measurement to avoid possible interference with the absorbance reading. 
	&#8203;NOTE: The optical absorbance of the acid blank read against deionized water (reference) should be less than 0.015; the optical absorbance of the standard and samples should be between 0.100 and 1.000. For samples with very high or very low iron content, the volumes of acid extract (supernatant) and diH2O may need to be adjusted (Table 2): if absorbance is greater than 1.0, use a smaller sample (supernatant) volume; when absorbance is lower than 0.1, use a higher volume of the supernatant. Sample volume (Vsmp) is taken into account when calculating each sample&#39;s tissue iron content (see step 6).</li>
</ol>
6. Calculation of tissue iron content
<ol>
	<li>Calculate non-heme tissue iron content with the following equation: 
	Tissue iron (&#181;g/g dry tissue) = <img alt="Equation 1" src="/files/ftp_upload/63469/63469eq01v2.jpg" /> 
	AT = absorbance of test sample 
	AB = absorbance of acid blank 
	AS = absorbance of standard 
	Fes = iron concentration of WISS (&#181;g Fe/mL) 
	W = weight of dry tissue (g) 
	Vsmp = sample volume (variable volume of Supernatant in Table 2 converted to mL) 
	Vf = final volume of acid mixture after overnight incubation at 65 &#176;C (corresponding to acid volume plus dry tissue volume in mL; if sample weights do not differ significantly, assume a constant volume &#8776; 1 mL) 
	Vstd = iron standard volume (volume of WISS in Table 2 converted to mL) 
	Vrv = final reaction volume (Total volume in Table 2 converted to mL)</li>
</ol>

<ol>
	<li>Muckenthaler, M. U., Rivella, S., Hentze, M. W., Galy, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+red+carpet+for+iron+metabolism.">A red carpet for iron metabolism.</a> Cell. 168, 344-361 (2017).</li><li>Pagani, A., Nai, A., Silvestri, L., Camaschella, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hepcidin+and+anemia:+A+tight+relationship.">Hepcidin and anemia: A tight relationship.</a> Frontiers in Physiology. 10, 1294 (2019).</li><li>Weiss, G., Ganz, T., Goodnough, L. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anemia+of+inflammation.">Anemia of inflammation.</a> Blood. 133 (1), 40-50 (2019).</li><li>Altamura, 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=Regulation+of+iron+homeostasis:+Lessons+from+mouse+models.">Regulation of iron homeostasis: Lessons from mouse models.</a> Molecular Aspects of Medicine. 75, 100872 (2020).</li><li>Torrance, J. D., Bothwell, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+simple+technique+for+measuring+storage+iron+concentrations+in+formalinised+liver+samples.">A simple technique for measuring storage iron concentrations in formalinised liver samples.</a> South African Journal of Medical Sciences. 33 (1), 9-11 (1968).</li><li>Torrence, J. D., Bothwell, T. H., Cook, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+iron+stores.">Tissue iron stores.</a> Methods in Haematology. , 104-109 (1980).</li><li>Rebouche, C. J., Wilcox, C. L., Widness, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microanalysis+of+non-heme+iron+in+animal+tissues.">Microanalysis of non-heme iron in animal tissues.</a> Journal of Biochemical and Biophysical Methods. 58 (3), 239-251 (2004).</li><li>Lesbordes-Brion, J. 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=Targeted+disruption+of+the+hepcidin+1+gene+results+in+severe+hemochromatosis.">Targeted disruption of the hepcidin 1 gene results in severe hemochromatosis.</a> Blood. 108, 1402-1405 (2006).</li><li>Jumbo-Lucioni, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systems+genetics+analysis+of+body+weight+and+energy+metabolism+traits+in+Drosophila+melanogaster.">Systems genetics analysis of body weight and energy metabolism traits in Drosophila melanogaster.</a> BMC Genomics. 11, 297 (2010).</li><li>Mandilaras, K., Pathmanathan, T., Missirlis, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iron+Absorption+in+Drosophila+melanogaster.">Iron Absorption in Drosophila melanogaster.</a> Nutrients. 5, 1622-1647 (2013).</li><li>Grundy, M. A., Gorman, N., Sinclair, P. R., Chorney, M. J., Gerhard, G. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-throughput+non-heme+iron+assay+for+animal+tissues.">High-throughput non-heme iron assay for animal tissues.</a> Journal of Biochemical and Biophysical Methods. 59, 195-200 (2004).</li><li>Adrian, W. J., Stevens, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Wet+versus+dry+weights+for+heavy+metal+toxicity+determinations+in+duck+liver.">Wet versus dry weights for heavy metal toxicity determinations in duck liver.</a> Journal of Wildlife Diseases. 15, 125-126 (1979).</li></ol>

The authors have no conflicts of interest.

A protocol for the measurement of the non-heme iron content in animal tissues is provided, using an adaptation of the bathophenanthroline-based colorimetric assay originally described by Torrance and Bothwell5,6. The critical steps of the method are tissue sample drying; protein denaturation and release of inorganic iron by acid hydrolysis; reduction of ferric (Fe3+) iron to the ferrous state (Fe2+) in the presence of the reducing agent thio...

Iron is an essential micronutrient, required for the function of proteins involved in crucial biological processes such as oxygen transport, energy production, or DNA synthesis. Importantly, both iron excess and iron deficiency are highly detrimental to human health, and tissue iron levels are finely regulated. Abnormal dietary iron absorption, iron-deficient diets, repeated blood transfusions, and chronic inflammation are common causes of iron-associated disorders that affect billions of people worldwide1,2,3.
Experimental animal models of iron overload or deficiency have been instrumental to advance our knowledge of the mechanisms involved in the systemic and cellular regulation of iron homeostasis4. Despite the substantial progress made during the last two decades, many key aspects remain elusive. In the coming years, the accurate measurement of total iron levels in animal tissues will remain a critical step to advance research in the iron biology field.
Most laboratories quantify tissue iron with either atomic absorption spectroscopy (AAS), inductively coupled plasma mass spectrometry (ICP-MS), or a colorimetric assay based on the reaction of non-heme iron with a bathophenanthroline reagent. The latter is based on the original method described by Torrance and Bothwell over 50 years ago5,6. While a variation of this method was subsequently developed employing ferrozine as an alternative to bathophenanthroline7, the latter remains the most widely cited chromogenic reagent in the literature.
The method of choice often depends on the available expertise and infrastructure. While AAS and ICP-MS are more sensitive, the colorimetric assay remains widely used because it presents the following important advantages: i) it excludes the contribution of heme iron derived from hemoglobin contained in red blood cells; ii) it does not require sophisticated analytical skills or highly expensive equipment; and iii) the original cuvette-based assay can be adapted to a microplate format, allowing higher sample throughput. The colorimetric approach presented in this work is routinely used to quantify alterations in tissue non-heme iron levels in a variety of experimental animal models of iron overload or iron deficiency, from rodents to fish and fruit fly. Here, a protocol for the measurement of the non-heme iron content in animal tissues is provided, using a simple, well-established, colorimetric assay that most laboratories should find easy to implement.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>96 well UV transparent plate</td>
			<td>Sarstedt</td>
			<td>82.1581.001</td>
			<td></td>
		</tr>
		<tr>
			<td>Analytical balance</td>
			<td>Kern</td>
			<td>ABJ 220-4M</td>
			<td></td>
		</tr>
		<tr>
			<td>Anhydrous sodium acetate</td>
			<td>Merck</td>
			<td>106268</td>
			<td></td>
		</tr>
		<tr>
			<td>Bathophenanthroline sulfonate (4,7-Diphenyl-1,10-phenantroline dissulfonic acid)</td>
			<td>Sigma-Aldrich</td>
			<td>B1375</td>
			<td></td>
		</tr>
		<tr>
			<td>C57BL/6 mice (Mus musculus)</td>
			<td>Charles River Laboratories</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Carbonyl iron powder, &#8805;99.5%</td>
			<td>Sigma-Aldrich</td>
			<td>44890</td>
			<td></td>
		</tr>
		<tr>
			<td>Disposable cuvettes in polymethyl methacrylate (PMMA)</td>
			<td>VWR</td>
			<td>634-0678P</td>
			<td></td>
		</tr>
		<tr>
			<td>Double distilled, sterile water</td>
			<td>B. Braun</td>
			<td>0082479E</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescence microplate reader</td>
			<td>BioTek Instruments</td>
			<td>FLx800</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrochloric acid, 37%</td>
			<td>Sigma-Aldrich</td>
			<td>258148</td>
			<td></td>
		</tr>
		<tr>
			<td>Microwave digestion oven and white teflon cups</td>
			<td>CEM</td>
			<td>MDS-2000</td>
			<td></td>
		</tr>
		<tr>
			<td>Nitric acid</td>
			<td>Fisher Scientific</td>
			<td>15687290</td>
			<td></td>
		</tr>
		<tr>
			<td>Oven</td>
			<td>Binder</td>
			<td>ED115</td>
			<td></td>
		</tr>
		<tr>
			<td>Rodent chow</td>
			<td>Harlan Laboratories</td>
			<td>2014S</td>
			<td>Teklad Global 14% Protein Rodent Maintenance Diet containing 175 mg/kg iron</td>
		</tr>
		<tr>
			<td>Sea bass (Dicentrarchus labrax)</td>
			<td>Sonrionansa</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sea bass feed</td>
			<td>Skretting</td>
			<td>L-2 Alterna 1P</td>
			<td></td>
		</tr>
		<tr>
			<td>Single beam UV-Vis spectrophotometer</td>
			<td>Shimadzu</td>
			<td>UV mini 1240</td>
			<td></td>
		</tr>
		<tr>
			<td>Thioglycolic acid</td>
			<td>Merck</td>
			<td>100700</td>
			<td></td>
		</tr>
		<tr>
			<td>Trichloroacetic acid</td>
			<td>Merck</td>
			<td>100807</td>
			<td></td>
		</tr>
	</tbody>
</table>

measurement of tissue non-heme iron content using a bathophenanthroline-based colorimetric assay

Iron is an essential micronutrient. Both iron overload and deficiency are highly detrimental to humans, and tissue iron levels are finely regulated. The use of experimental animal models of iron overload or deficiency has been instrumental to advance knowledge of the mechanisms involved in the systemic and cellular regulation of iron homeostasis. The measurement of total iron levels in animal tissues is commonly performed with atomic absorption spectroscopy or with a colorimetric assay based on the reaction of non-heme iron with a bathophenanthroline reagent. For many years, the colorimetric assay has been used for the measurement of the non-heme iron content in a wide range of animal tissues. Unlike atomic absorption spectroscopy, it excludes the contribution of heme iron derived from hemoglobin contained in red blood cells. Moreover, it does not require sophisticated analytical skills or highly expensive equipment, and can thus be easily implemented in most laboratories. Finally, the colorimetric assay can be either cuvette-based or adapted to a microplate format, allowing higher sample throughput. The present work provides a well-established protocol that is suited for the detection of alterations in tissue iron levels in a variety of experimental animal models of iron overload or iron deficiency.

Cuvette versus 96-well microplate comparison 
The measurement of tissue non-heme iron by reaction with a bathophenanthroline reagent originally described by Torrance and Bothwell5,6 relies on the use of a spectrophotometer for absorbance reading. Hence, the volumes employed in the chromogen reaction are compatible with the size of a regular spectrophotometer cuvette. The present work describes a method adaptation in which the chromogen react...

Watch this Scientific Journal Video about Measurement of Tissue Non-Heme Iron Content using a Bathophenanthroline-Based Colorimetric Assay at JoVE.com

Measurement of Tissue Non-Heme Iron Content using a Bathophenanthroline-Based Colorimetric Assay

Here, a protocol for the measurement of the non-heme iron content in animal tissues is provided, using a simple, well-established colorimetric assay that can be easily implemented in most laboratories.

Iron is an essential micronutrient. Both iron overload and deficiency are highly detrimental to humans, and tissue iron levels are finely regulated. The ...

measurement-tissue-non-heme-iron-content-using-bathophenanthroline

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4.2K Views.  Universidade do Porto. Here, a protocol for the measurement of the non-heme iron content in animal tissues is provided, using a simple, well-established colorimetric assay that can be easily implemented in most laboratories.

Video: Measurement of Tissue Non-Heme Iron Content using a Bathophenanthroline-Based Colorimetric Assay

Accurate and Simple Measurement of the Pro-inflammatory Cytokine IL-1&beta; using a Whole Blood Stimulation Assay

Inflammatory processes resulting from the secretion of soluble mediators by immune cells, lead to various manifestations in skin, joints and other tissues as well as altered cytokine homeostasis. The innate immune system plays a crucial role in recognizing pathogens and other endogenous danger stimuli. One of the major cytokines released by innate immune cells is Interleukin (IL)-1. Therefore, we utilize a whole blood stimulation assay in order to measure the secretion of inflammatory cytokines and specifically of the pro-inflammatory cytokine IL-1&beta; 1, 2, 3.
Patients with genetic dysfunctions of the innate immune system causing autoinflammatory syndromes show an exaggerated release of mature IL-1&beta; upon stimulation with LPS alone. In order to evaluate the innate immune component of patients who present with inflammatory-associated pathologies, we use a specific immunoassay to detect cellular immune responses to pathogen-associated molecular patterns (PAMPs), such as the gram-negative bacterial endotoxin, lipopolysaccharide (LPS). These PAMPs are recognized by pathogen recognition receptors (PRRs), which are found on the cells of the innate immune system 4, 5, 6, 7. A primary signal, LPS, in conjunction with a secondary signal, ATP, is necessary for the activation of the inflammasome, a multiprotein complex that processes pro-IL-1&beta; to its mature, bioactive form 4, 5, 6, 8, 9, 10.
The whole blood assay requires minimal sample manipulation to assess cytokine production when compared to other methods that require labor intensive isolation and culturing of specific cell populations. This method differs from other whole blood stimulation assays; rather than diluting samples with a ratio of RPMI media, we perform a white blood cell count directly from diluted whole blood and therefore, stimulate a known number of white blood cells in culture 2. The results of this particular whole blood assay demonstrate a novel technique useful in elucidating patient cohorts presenting with autoinflammatory pathophysiologies.

Accurate and Simple Measurement of the Pro-inflammatory Cytokine IL-1&amp;#946; using a Whole Blood Stimulation Assay

We describe a simple immunoassay to measure the production of pro-inflammatory cytokines, such as IL-1 beta production, in patients presenting with autoinflammatory phenotypes. By activating cells in whole blood cultures with pathogen-associated molecular patterns, specifically with lipopolysaccharide, cytokine secretion can be conveniently evaluated in whole blood supernatants.

Inflammatory processes resulting from the secretion of soluble mediators by immune cells, lead to various manifestations in skin, joints and other tissues ...

Segmentation and Measurement of Fat Volumes in Murine Obesity Models Using X-ray Computed Tomography

Obesity is associated with increased morbidity and mortality as well as reduced metrics in quality of life.1 Both environmental and genetic factors are associated with obesity, though the precise underlying mechanisms that contribute to the disease are currently being delineated.2,3 Several small animal models of obesity have been developed and are employed in a variety of studies.4 A critical component to these experiments involves the collection of regional and/or total animal fat content data under varied conditions.
Traditional experimental methods available for measuring fat content in small animal models of obesity include invasive (e.g. ex vivo measurement of fat deposits) and non-invasive (e.g. Dual Energy X-ray Absorptiometry (DEXA), or Magnetic Resonance (MR)) protocols, each of which presents relative trade-offs. Current invasive methods for measuring fat content may provide details for organ and region specific fat distribution, but sacrificing the subjects will preclude longitudinal assessments. Conversely, current non-invasive strategies provide limited details for organ and region specific fat distribution, but enable valuable longitudinal assessment. With the advent of dedicated small animal X-ray computed tomography (CT) systems and customized analytical procedures, both organ and region specific analysis of fat distribution and longitudinal profiling may be possible. Recent reports have validated the use of CT for in vivo longitudinal imaging of adiposity in living mice.5,6 Here we provide a modified method that allows for fat/total volume measurement, analysis and visualization utilizing the Carestream Molecular Imaging Albira CT system in conjunction with PMOD and Volview software packages.

Fat content analysis is routinely conducted in studies utilizing murine obesity models. Emerging methods in small animal CT imaging and analysis are providing for longitudinal detail rich fat content analysis. Here we detail step by step procedures for performing small animal CT imaging, analysis, and visualization.

Obesity is associated with increased morbidity and mortality as well as reduced metrics in quality of life.1 Both environmental and genetic factors are ...

Epidural Intracranial Pressure Measurement in Rats Using a Fiber-optic Pressure Transducer

Elevated intracranial pressure (ICP) is a significant problem in several forms of ischemic brain injury including stroke, traumatic brain injury and cardiac arrest. This elevation may result in further neurological injury, in the form of transtentorial herniation1,2,3,4, midbrain compression, neurological deficit or increased cerebral infarct2,4. Current therapies are often inadequate to control elevated ICP in the clinical setting5,6,7 . Thus there is a need for accurate methods of ICP measurement in animal models to further our understanding of the basic mechanisms and to develop new treatments for elevated ICP.
In both the clinical and experimental setting ICP cannot be estimated without direct measurement. Several methods of ICP catheter insertion currently exist. Of these the intraventricular catheter has become the clinical 'gold standard' of ICP measurement in humans8. This method involves the partial removal of skull and the instrumentation of the catheter through brain tissue. Consequently, intraventricular catheters have an infection rate of 6-11%9. For this reason, subdural and epidural cannulations have become the preferred methods in animal models of ischemic injury. 
Various ICP measurement techniques have been adapted for animal models, and of these, fluid-filled telemetry catheters10 and solid state catheters are the most frequently used11,12,13,14,15. The fluid-filled systems are prone to developing air bubbles in the line, resulting in false ICP readings. Solid state probes avoid this problem (Figure 1). An additional problem is fitting catheters under the skull or into the ventricles without causing any brain injury that might alter the experimental outcomes. Therefore, we have developed a method that places an ICP catheter contiguous with the epidural space, but avoids the need to insert it between skull and brain. 
An optic fibre pressure catheter (420LP, SAMBA Sensors, Sweden) was used to measure ICP at the epidural location because the location of the pressure sensor (at the very tip of the catheter) was found to produce a high fidelity ICP signal in this model. There are other manufacturers of similar optic fibre technologies13 that may be used with our methodology. Alternative solid state catheters, which have the pressure sensor located at the side of the catheter tip, would not be appropriate for this model as the signal would be dampened by the presence of the monitoring screw. 
Here, we present a relatively simple and accurate method to measure ICP. This method can be used across a wide range of ICP related animal models.

A novel technique to record the pressures within the skull is described. The minimally invasive method uses a fibre-optic pressure sensing system to accurately measure intracranial pressure (ICP) in anaesthetized rats without causing significant brain trauma. The technique may be used in a wide range of experimental models.

Elevated intracranial pressure (ICP) is a significant problem in several forms of ischemic brain injury including stroke, traumatic brain injury and ...

Transplantation of Pulmonary Valve Using a Mouse Model of Heterotopic Heart Transplantation

Tissue engineered heart valves, especially decellularized valves, are starting to gain momentum in clinical use of reconstructive surgery with mixed results. However, the cellular and molecular mechanisms of the neotissue development, valve thickening, and stenosis development are not researched extensively. To answer the above questions, we developed a murine heterotopic heart valve transplantation model. A heart valve was harvested from a valve donor mouse and transplanted to a heart donor mouse. The heart with a new valve was transplanted heterotopically to a recipient mouse. The transplanted heart showed its own heartbeat, independent of the recipient&#8217;s heartbeat. The blood flow was quantified using a high frequency ultrasound system with a pulsed wave Doppler. The flow through the implanted pulmonary valve showed forward flow with minimal regurgitation and the peak flow was close to 100 mm/sec. This murine model of heart valve transplantation is highly versatile, so it can be modified and adapted to provide different hemodynamic environments and/or can be used with various transgenic mice to study neotissue development in a tissue engineered heart valve.

In order to understand the cellular and molecular mechanisms underlying neotissue formation and stenosis development in tissue engineered heart valves, a murine model of heterotopic heart valve transplantation was developed. A pulmonary heart valve was transplanted to recipient using the heterotopic heart transplantation technique.

Tissue engineered heart valves, especially decellularized valves, are starting to gain momentum in clinical use of reconstructive surgery with mixed ...

A High-content In Vitro Pancreatic Islet &#946;-cell Replication Discovery Platform

Loss of insulin-producing &#946;-cells is a central feature of diabetes. While a variety of potential replacement therapies are being explored, expansion of endogenous insulin-producing pancreatic islet &#946;-cells remains an attractive strategy. &#946;-cells have limited spontaneous regenerative activity; consequently, a crucial research effort is to develop a precise understanding of the molecular pathways that restrain &#946;-cell growth and to identify drugs capable of overcoming these restraints. Herein an automated high-content image-based primary-cell screening method to identify &#946;-cell replication-promoting small molecules is presented. Several, limitations of prior methodologies are surmounted. First, use of primary islet cells rather than an immortalized cell-line maximizes retention of in vivo growth restraints. Second, use of mixed-composition islet-cell cultures rather than a &#946;-cell-line allows identification of both lineage-restricted and general growth stimulators. Third, the technique makes practical the use of primary islets, a limiting resource, through use of a 384-well format. Fourth, detrimental experimental variability associated with erratic islet culture quality is overcome through optimization of isolation, dispersion, plating and culture parameters. Fifth, the difficulties of accurately and consistently measuring the low basal replication rate of islet endocrine-cells are surmounted with optimized immunostaining parameters, automated data acquisition and data analysis; automation simultaneously enhances throughput and limits experimenter bias. Notable limitations of this assay are the use of dispersed islet cultures which disrupts islet architecture, the use of rodent rather than human islets and the inherent limitations of throughput and cost associated with the use of primary cells. Importantly, the strategy is easily adapted for human islet replication studies. This assay is well suited for investigating the mitogenic effect of substances on &#946;-cells and the molecular mechanisms that regulate &#946;-cell growth.

A High-content In Vitro Pancreatic Islet &amp;#946;-cell Replication Discovery Platform

Critical challenges for the diabetes research field are to understand the molecular mechanisms that regulate islet &#946;-cell replication and to develop methods for stimulating &#946;-cell regeneration. Herein a high-content screening method to identify and assess the &#946;-cell replication-promoting activity of small molecules is presented.

Loss of insulin-producing &#946;-cells is a central feature of diabetes. While a variety of potential replacement therapies are being explored, expansion ...

Absolute Quantification of A&#946;1-42 in CSF Using a Mass Spectrometric Reference Measurement Procedure

Alzheimer's disease (AD) is the most common neurodegenerative disease among the elderly and accounts for 60-80% of all cases of dementia. Currently, the diagnosis of AD is based on cognitive tests and mental state exams, but the peptide amyloid-beta (A&#946;) in cerebrospinal fluid (CSF) is increasingly used in clinical trials and settings. As for most protein and peptide biomarkers, quantification is performed using antibody-based techniques, such as enzyme-linked immunosorbent assay (ELISA). However, intra- and inter-laboratory variability in these assays hamper its use as a diagnostic marker in clinical routine.
An antibody-independent Reference Measurement Procedure (RMP) was developed based on solid-phase extraction (SPE) and liquid chromatography (LC)-tandem mass spectrometry (MS/MS), where stable, isotope-labeled A&#946; peptides were used as internal standards, enabling absolute quantification. A high-resolution quadrupole-orbitrap hybrid instrument was used for the measurements. The method allows for the quantification of CSF A&#946;1-42 between 150-4,000 pg/mL.

Absolute Quantification of A&amp;#946;&lt;sub&gt;1-42&lt;/sub&gt; in CSF Using a Mass Spectrometric Reference Measurement Procedure

A reference measurement procedure for the absolute quantification of A&#946;1-42 in human CSF based on solid-phase extraction and liquid chromatography tandem mass spectrometry is described.

Alzheimer's disease (AD) is the most common neurodegenerative disease among the elderly and accounts for 60-80% of all cases of dementia. Currently, the ...

Tracking Superparamagnetic Iron Oxide-labeled Mesenchymal Stem Cells using MRI after Intranasal Delivery in a Traumatic Brain Injury Murine Model

Stem cell-based therapies for brain injuries, such as traumatic brain injury (TBI), are a promising approach for clinical trials. However, technical hurdles such as invasive cell delivery and tracking with low transplantation efficiency remain challenges in translational stem-based therapy. This article describes an emerging technique for stem cell labeling and tracking based on the labeling of the mesenchymal stem cells (MSCs) with superparamagnetic iron oxide (SPIO)&#160;nanoparticles, as well as intranasal delivery of the labeled MSCs. These nanoparticles are fluorescein isothiocyanate (FITC)-embedded and safe to label the MSCs, which are subsequently delivered to the brains of TBI-induced mice by the intranasal route. They are then tracked non-invasively in vivo by real-time magnetic resonance imaging (MRI). Important advantages of this technique that combines SPIO for cell labeling and intranasal delivery include (1) non-invasive, in vivo MSC tracking after delivery for long tracking periods, (2) the possibility of multiple dosing regimens due to the non-invasive route of MSC delivery, and (3) possible applications to humans, owing to the safety of SPIO, non-invasive nature of the cell-tracking method by MRI, and route of administration.

Presented here is a protocol for non-invasive mesenchymal stem cell (MSC) delivery and tracking in a mouse model of traumatic brain injury. Superparamagnetic iron oxide&#160;nanoparticles are employed as a magnetic resonance imaging (MRI) probe for MSC labeling and non-invasive in vivo tracking following intranasal delivery using real-time MRI.

Stem cell-based therapies for brain injuries, such as traumatic brain injury (TBI), are a promising approach for clinical trials. However, technical ...

Segmentation and Linear Measurement for Body Composition Analysis using Slice-O-Matic and Horos

Body composition is associated with risk of disease progression and treatment complications in a variety of conditions. Therefore, quantification of skeletal muscle mass and adipose tissues on Computed Tomography (CT) and/or Magnetic Resonance Imaging (MRI) may inform surgery risk evaluation and disease prognosis. This article describes two quantification methods originally described by Mourtzakis et al. and Avrutin et al.: tissue segmentation and linear measurement of skeletal muscle. Patients' cross-sectional image at the midpoint of the third lumbar vertebra was obtained for both measurements. For segmentation, the images were imported into Slice-O-Matic and colored for skeletal muscle, intramuscular adipose tissue, visceral adipose tissue, and subcutaneous adipose tissue. Then, surface areas of each tissue type were calculated using the tag surface area function. For linear measurements, the height and width of bilateral psoas and paraspinal muscles at the level of the third lumbar vertebra are measured and the calculation using these four values yield the estimated skeletal muscle mass. Segmentation analysis provides quantitative, comprehensive information about the patients' body composition, which can then be correlated with disease progression. However, the process is more time-consuming and requires specialized training. Linear measurements are an efficient and clinic-friendly tool for quick preoperative evaluation. However, linear measurements do not provide information on adipose tissue composition. Nonetheless, these methods have wide applications in a variety of diseases to predict surgical outcomes, risk of disease progression and inform treatment options for patients.

Segmentation and linear measurements quantify skeletal muscle mass and adipose tissues using Computed Tomography and/or Magnetic Resonance Imaging images. Here, we outline the use of Slice-O-Matic software and Horos image viewer for rapid and accurate analysis of body composition. These methods can provide important information for prognosis and risk stratification.

Body composition is associated with risk of disease progression and treatment complications in a variety of conditions. Therefore, quantification of ...

Measurement of Tissue Oxygenation Using Near-Infrared Spectroscopy in Patients Undergoing Hemodialysis

Near-infrared spectroscopy (NIRS) has recently been applied as a tool to measure regional oxygen saturation (rSO2), a marker of tissue oxygenation, in clinical settings including cardiovascular and brain surgery, neonatal monitoring and prehospital medicine. The NIRS monitoring devices are real-time and noninvasive, and have mainly been used for evaluating cerebral oxygenation in critically ill patients during an operation or intensive care. Thus far, the use of NIRS monitoring in patients with chronic kidney disease (CKD) including hemodialysis (HD) has been limited; therefore, we investigated rSO2 values in some organs during HD. We monitored rSO2 values using a NIRS device transmitting near-infrared light at 2 wavelengths of attachment. The HD patients were placed in a supine position, with rSO2 measurement sensors attached to the foreheads, the right hypochondrium and the lower legs to evaluate rSO2 in the brain, liver and lower leg muscles, respectively. NIRS monitoring could be a new approach to clarify changes in organ oxygenation during HD or factors affecting tissue oxygenation in CKD patients. This article describes a protocol to measure tissue oxygenation represented by rSO2 as applied in HD patients.

We present a protocol to measure regional oxygen saturation (rSO2) in hemodialysis (HD) patients by using a near-infrared spectroscopy monitor. The rSO2 value is an index of tissue oxygenation. This noninvasive and real-time monitoring could be useful for confirming changes in organ oxygenation during HD.

Near-infrared spectroscopy (NIRS) has recently been applied as a tool to measure regional oxygen saturation (rSO2), a marker of tissue oxygenation, in ...

Human Subcutaneous Adipose Tissue Sampling Using a Mini-Liposuction Technique

Studies on adipose tissue are useful in understanding metabolic and other conditions. Human subcutaneous adipose tissue is accessible. With appropriate training and strict adherence to aseptic technique, subcutaneous adipose samples can be safely and efficiently obtained in a non-clinical setting by researchers. Following the administration of local anesthetic lateral to the umbilicus, a 14 G needle attached to a 5 or 10 mL syringe is inserted through the skin into the subcutaneous tissue. Under suction, the syringe is moved in a reciprocating, slicing motion to isolate fragments of adipose tissue. Withdrawing the plunger is enough to ensure that adipose tissue fragments are aspirated through the needle into the syringe. A single biopsy can collect about 200 mg of tissue. This biopsy technique is very safe for both participants and research staff. Following the biopsy, participants can resume most everyday activities, although they should avoid swimming and overly strenuous activities for 48 h to avoid excessive bleeding. Participants can safely undergo 2 biopsies within a single day, meaning that the technique can be applied in before-after acute intervention studies.

The manuscript and associated video demonstrate a percutaneous biopsy technique to obtain samples of subcutaneous adipose tissue from areas surrounding the umbilicus. This method is a low-risk and efficient way to investigate a range of parameters (e.g., gene or protein expression, enzyme activity, lipid content) within adipose tissue.

Studies on adipose tissue are useful in understanding metabolic and other conditions. Human subcutaneous adipose tissue is accessible. With appropriate ...