The authors would like to thank Hong Jiang, Ph.D. and Deepa Parathasarthy, MPH, BDS for the technical assistance.

1. Whole Blood Collection
<ol>
	<li>Collect venous blood from humans or from experimental animals in NEM/EDTA containing tubes.</li>
	<li>Immediately spin down blood in a benchtop centrifuge at 14,300 rcf (relative centrifugal force) for 7 minutes to prepare plasma and red blood cell pellet.</li>
	<li>Prepare plasma samples for high performance liquid chromatography (HPLC) and chemiluminescence detection (CLD) analysis. 
	HPLC: Add 1:1 volume of cold methanol to plasma, vortex and centrifuge at 13,200 rpm for 10 minutes to precipitate plasma proteins. Collect supernatant for HPLC analysis. 
	CLD: aliquot a sample and preincubate with sulfanilamide and mercuric chloride to specifically assay nitrosothiols.</li>
	<li>Prepare red cell pellet for HPLC and CLD analysis. 
	HPLC: Add 1:4 red cell pellet to a hypotonic lysis solution containing 10 mM NEM, 2.5 mM EDTA and 10 mM ferricyanide. Vortex thoroughly and then add 1:1 methanol, vortex and centrifuge at 13,200 rpm for 10 minutes to precipitate protein. Collect supernatant for HPLC analysis. 
	CLD. Add 1:4 red cell pellet to a hypotonic lysis solution containing 10 mM EDTA, 2.5 mM EDTA and 10 mM Ferricyanide. Aliquot samples to tubes containing sulfanilamide and mercuric chloride for specific detection of nitrosothiols.</li>
</ol>
2. Tissue Extraction and Preparation
<ol>
	<li>To determine tissue levels of NO metabolites, it is first necessary to harvest blood free tissue for sample preparation as described above. A full blood exchange will take place by infusing physiological buffer through the apex of the left ventricle. Once all blood is removed, tissues of interest can then be harvested.</li>
	<li>Homogenize tissue samples and prepare samples as described above for HPLC and CLD analysis.</li>
</ol>
3. Aortic Rings Isolation for Endothelial Function
Tissue Organ Bath
<ol>
	<li>Mice will be anesthetized with diethyl ether until no longer responsive to toe pinch, and undergo cervical dislocation prior to surgery. A thoracotomy is performed to expose thoracic and abdominal aorta. A 25 gauge syringe is inserted into the apex of left ventricle and perfused free of blood with oxygenated Krebs Henseleit buffer.</li>
	<li>The right atrium is cut to provide an exit for blood. Abdominal aorta will be removed and cleaned of adventitia.</li>
	<li>Rings will be cut into 2 mm long segments and mounted on a four-channel tissue organ bath (DMT 720MO, AD Instruments) bathed in a physiological buffer solution.</li>
	<li>Vessel rings are maintained in 10-ml organ baths with oxygenated Krebs buffer (95% O2 and 5% CO2) at 37 &deg;C. One gram pretension is placed on each aortic ring (appropriate starting tension for optimal vasomotor function as determined in previous experiments). An eight-channel octal bridge (Powerlab) and data-acquisition software (Chart version 5.2.2) are used to record all force measurements.</li>
	<li>Rings are allowed to equilibrate for 80 minutes with the buffer in each organ bath changed every 20 min. After equilibration for 80 min, 1 &mu;M phenylephrine is added to each ring for submaximal contraction.</li>
	<li>After stabilization, endothelial agonist such as acetylcholine will be added to determine NO production and degree of vessel relaxation. After the dose response to acetylcholine, baths will be rinsed and recontracted and then treated with an exogenous source of nitric oxide, sodium nitroprusside to determine responsiveness of smooth muscle and to get a value for 100% relaxation.</li>
	<li>NO scavengers can be added to bath to clearly illustrate release of NO and inhibition of vessel relaxation.</li>
</ol>
4. Representative Results
Use of the ENO-20 dedicated HPLC provides an easy to use high throughput method for specific and sensitive detection of nitrite and nitrate in biological matrices. The principle of detection and an original chromatogram is shown in Figure 1. This method can be used for any biological sample for determining nitrite and nitrate. CLD based detection of NO metabolites requires a chemical derivitization step to determine the molecular source of the NO. The experimental setup for simultaneous oxidative denitrosation and reductive denitrosation for the chemiluminescence detector is shown in Figure 2. The reaction vessel on the right is filled with 800mM ferricyanide in PBS pH 7.4 and the reaction vessel on the left is filled with potassium iodide/iodine mixture in acetic acid for reduction denitrosation (Figure 2A). The entire setup is shown in Figure 2B. Figure 3 illustrates group specific denitrosation assays that can detect and quantify nitrite, nitrosothiols, nitrosamines as well as nitrosyl heme products. This method has been previously described and validated4,5. These important biochemical analyses can easily be correlated with functional studies on isolated aortic rings to determine endothelial NO production in experimental animals. This classical pharmacological experiment can easily and accurately assess endothelial NO function and production. Measuring vessel reactivity to endothelial agonists such as acetylcholine can directly determine endothelial NO production which can then be correlated with biochemical biomarkers detected in blood and tissue of the experimental animals. A typical representation of a dose response to acetylcholine is shown in Figure 4. Healthy control mice with normal endothelial function respond to acetylcholine by relaxing. Mice with endothelial dysfunction (hypercholesterolemic mice) show reduced relaxation due to reduced NO production to the same stimulus.
<img alt="Figure 1" src="/files/ftp_upload/3722/3722fig1.jpg" /> 
Figure 1. Principle of detection of nitrite and nitrate by ENO-20 and sample chromatogram. (Top) Schematic of ENO-20 method of detection for nitrite and nitrate. (bottom) Standard chromotogram of 10 pmol nitrite and nitrate injected into ENO-20 (100 &mu;l of 100 nM solution of nitrite and nitrate). Sensitivity of 1 nM for each anion with 100 &mu;l injection volume. No interference with protein or colored species.
<img alt="Figure 2" src="/files/ftp_upload/3722/3722fig2.jpg" /> 
Figure 2. CLD experimental setup using both oxidative denitrosation by ferricyanide and reductive denitrosation using iodide/iodine assay with gas phase detection of purged nitric oxide gas.
<img alt="Figure 3" src="/files/ftp_upload/3722/3722fig3.jpg" /> 
Figure 3. (Panel A) Chemiluminescence detection of nitrite, RSNO, RNNO in reductive denitrosation assay by sample preincubation with group specific chemical reagents. Subtraction of peak areas allow detection of nitrite and RSNOs. (Panel B) Chemiluminescent detection of nitrosyl heme species using oxidative denitrosation solution of ferricyanide. This method is specific for NO-heme products with no cross reactivity with RSNOs (GSNO or SNO-albumin), or RNNO (NO-pyrrolidine and N-nitroso-albumin).
<img alt="Figure 4" src="/files/ftp_upload/3722/3722fig4.jpg" /> 
Figure 4. Ex vivo organ bath on isolated aortic rings provides a direct measure of endothelial NO production that can then be correlated with biochemical biomarkers detected by HPLC and CLD. This figure illustrates reduced relaxation in mice with endothelial dysfunction due to decreased NO production.

<ol>
	<li>Kelm, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nitric+oxide+metabolism+and+breakdown.">Nitric oxide metabolism and breakdown.</a> Biochimica et Biophysica Acta. 1411, 273-289 (1999).</li><li>Furchgott, R. F., Zawadzki, J. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+obligatory+role+of+endothelial+cells+in+the+relaxation+of+arterial+smooth+muscle+by+acetycholine.">The obligatory role of endothelial cells in the relaxation of arterial smooth muscle by acetycholine.</a> Nature. 288, 373-376 (1980).</li><li>Ignarro, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endothelium-derived+relaxing+factor+produced+and+released+from+artery+and+vein+is+nitric+oxide.">Endothelium-derived relaxing factor produced and released from artery and vein is nitric oxide.</a> Proc. Natl. Acad Sci. U.S.A. 84, 9265-9269 (1987).</li><li>Feelisch, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Concomitant+S-,+N-,+and+heme-nitrosylation+in+biological+tissues+and+fluids:+implications+for+the+fate+of+NO+in+vivo.">Concomitant S-, N-, and heme-nitrosylation in biological tissues and fluids: implications for the fate of NO in vivo.</a> FASEB J. 16, 1775-1785 (2002).</li><li>Wang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+nitric+oxide+levels+in+the+red+cell:+validation+of+tri-iodide-based+chemiluminescence+with+acid-sulfanilamide+pretreatment.">Measurement of nitric oxide levels in the red cell: validation of tri-iodide-based chemiluminescence with acid-sulfanilamide pretreatment.</a> J. Biol. Chem. 281, 26994-27002 (2006).</li><li>Angelo, M., Singel, D. J., Stamler, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+S-nitrosothiol+(SNO)+synthase+function+of+hemoglobin+that+utilizes+nitrite+as+a+substrate.">An S-nitrosothiol (SNO) synthase function of hemoglobin that utilizes nitrite as a substrate.</a> Proc. Natl. Acad. Sci. U.S.A. 103, 8366-8371 (2006).</li><li>Bryan, N. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bound+NO+in+human+red+blood+cells:+fact+or+artifact.">Bound NO in human red blood cells: fact or artifact.</a> Nitric Oxide. 10, 221-228 (2004).</li><li>Feelisch, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+Processing+of+Nitrite+in+Hypoxia:+An+Intricate+Interplay+of+Nitric+Oxide-Generating+and+-Scavenging+Systems.">Tissue Processing of Nitrite in Hypoxia: An Intricate Interplay of Nitric Oxide-Generating and -Scavenging Systems.</a> J. Biol. Chem. 283, 33927-33934 (2008).</li><li>Bryan, N. S., Grisham, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+to+detect+nitric+oxide+and+its+metabolites+in+biological+samples.">Methods to detect nitric oxide and its metabolites in biological samples.</a> Free Radic. Biol. Med. 43, 645-657 (2007).</li><li>Lundberg, J. O., Weitzberg, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NO+generation+from+inorganic+nitrate+and+nitrite:+Role+in+physiology,+nutrition+and+therapeutics.">NO generation from inorganic nitrate and nitrite: Role in physiology, nutrition and therapeutics.</a> Arch. Pharm. Res. 32, 1119-1126 (2009).</li><li>Lundberg, J. O., Weitzberg, E., Gladwin, M. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+nitrate-nitrite-nitric+oxide+pathway+in+physiology+and+therapeutics.">The nitrate-nitrite-nitric oxide pathway in physiology and therapeutics.</a> Nat. Rev. Drug. Discov. 7, 156-157 (2008).</li></ol>

No conflicts of interest declared.

The methods described here for the quantification of relevant NO metabolites in multiple biological compartments will allow for fingerprinting of NO biology in health and disease that can be correlated with functional measurements of NO by the endothelium. These methods require simple sample preparation with potential for adapting for high throughput. The relative quantity of these molecules can help understand the production of NO and its metabolic fate in a number of experimental models of disease and even serial sampl...

<table border="1">
<tbody>
 <tr>
 <td>Name of the reagent</td>
 <td>Company</td>
 <td>Catalogue number</td>
 </tr>
 <tr>
 <td>N-ethylmaleimide</td>
 <td>Thermo Scientific</td>
 <td>23030</td>
 </tr>
 <tr>
 <td>EDTA</td>
 <td>Sigma-Aldrich</td>
 <td>E7889</td>
 </tr>
 <tr>
 <td>Potassium Ferricyanide</td>
 <td>Fluka</td>
 <td>60299</td>
 </tr>
 <tr>
 <td>HPLC</td>
 <td>Eicom Corp</td>
 <td>ENO-20</td>
 </tr>
 <tr>
 <td>Autosampler</td>
 <td>Alcott</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>DMT Myograph</td>
 <td>AD Instruments</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>PowerLab</td>
 <td>AD Instruments</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Chemiluminescent </td>
 <td>EcoPhysics</td>
 <td>CLD 88Y</td>
 </tr>
 <tr>
 <td>Centrifuge</td>
 <td>Eppendorf </td>
 <td>5415D </td>
 </tr>
 <tr>
 <td>Acetylcholine</td>
 <td>Sigma-Aldrich</td>
 <td>A6625</td>
 </tr>
 <tr>
 <td>R-(-) Phenylephrine</td>
 <td>Sigma-Aldrich</td>
 <td>P6126</td>
 </tr>
</tbody>
</table>

analytical techniques for assaying nitric oxide bioactivity

Nitric oxide (NO) is a diatomic free radical that is extremely short lived in biological systems (less than 1 second in circulating blood)1. NO may be considered one of the most important signaling molecules produced in our body, regulating essential functions including but not limited to regulation of blood pressure, immune response and neural communication. Therefore its accurate detection and quantification in biological matrices is critical to understanding the role of NO in health and disease. With such a short physiological half life of NO, alternative strategies for the detection of reaction products of NO biochemistry have been developed. The quantification of relevant NO metabolites in multiple biological compartments provides valuable information with regards to in vivo NO production, bioavailability and metabolism. Simply sampling a single compartment such as blood or plasma may not always provide an accurate assessment of whole body NO status, particularly in tissues. The ability to compare blood with select tissues in experimental animals will help bridge the gap between basic science and clinical medicine as far as diagnostic and prognostic utility of NO biomarkers in health and disease. Therefore, extrapolation of plasma or blood NO status to specific tissues of interest is no longer a valid approach. As a result, methods continue to be developed and validated which allow the detection and quantification of NO and NO-related products/metabolites in multiple compartments of experimental animals in vivo. The established paradigm of NO biochemistry from production by NO synthases to activation of soluble guanylyl cyclase (sGC) to eventual oxidation to nitrite (NO2-) and nitrate (NO3-) may only represent part of NO's effects in vivo. The interaction of NO and NO-derived metabolites with protein thiols, secondary amines, and metals to form S-nitrosothiols (RSNOs), N-nitrosamines (RNNOs), and nitrosyl-heme respectively represent cGMP-independent effects of NO and are likely just as important physiologically as activation of sGC by NO. A true understanding of NO in physiology is derived from in vivo experiments sampling multiple compartments simultaneously. Nitric oxide (NO) methodology is a complex and often confusing science and the focus of many debates and discussion concerning NO biochemistry. The elucidation of new mechanisms and signaling pathways involving NO hinges on our ability to specifically, selectively and sensitively detect and quantify NO and all relevant NO products and metabolites in complex biological matrices. Here, we present a method for the rapid and sensitive analysis of nitrite and nitrate by HPLC as well as detection of free NO in biological samples using in vitro ozone based chemiluminescence with chemical derivitazation to determine molecular source of NO as well as ex vivo with organ bath myography.

Watch this Scientific Journal Video about Analytical Techniques for Assaying Nitric Oxide Bioactivity at JoVE.com

Analytical Techniques for Assaying Nitric Oxide Bioactivity

The endogenous production of nitric oxide (NO) regulates a wide variety of biological functions. It is becoming increasingly clear that disruption or dysregulation of NO based signaling is involved in many human diseases. Methods to quantify relevant NO metabolites may provide novel diagnostic or prognostic biomarkers for human disease.

Nitric oxide (NO) is a diatomic free radical that is extremely short lived in biological systems (less than 1 second in circulating blood)1. NO may be ...

analytical-techniques-for-assaying-nitric-oxide-bioactivity

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17.9K Views.  University of Texas Health Science Center at Houston. The endogenous production of nitric oxide (NO) regulates a wide variety of biological functions. It is becoming increasingly clear that disruption or dysregulation of NO based signaling is involved in many human diseases. Methods to quantify relevant NO metabolites may provide novel diagnostic or prognostic biomarkers for human disease.

Video: Analytical Techniques for Assaying Nitric Oxide Bioactivity

5/6th Nephrectomy in Combination with High Salt Diet and Nitric Oxide Synthase Inhibition to Induce Chronic Kidney Disease in the Lewis Rat

Chronic kidney disease (CKD) is a global problem. Slowing CKD progression is a major health priority. Since CKD is characterized by complex derangements of homeostasis, integrative animal models are necessary to study development and progression of CKD. To study development of CKD and novel therapeutic interventions in CKD, we use the 5/6th nephrectomy ablation model, a well known experimental model of progressive renal disease, resembling several aspects of human CKD. The gross reduction in renal mass causes progressive glomerular and tubulo-interstitial injury, loss of remnant nephrons and development of systemic and glomerular hypertension. It is also associated with progressive intrarenal capillary loss, inflammation and glomerulosclerosis. Risk factors for CKD invariably impact on endothelial function. To mimic this, we combine removal of 5/6th of renal mass with nitric oxide (NO) depletion and a high salt diet. After arrival and acclimatization, animals receive a NO synthase inhibitor (NG-nitro-L-Arginine) (L-NNA) supplemented to drinking water (20 mg/L) for a period of 4 weeks, followed by right sided uninephrectomy. One week later, a subtotal nephrectomy (SNX) is performed on the left side. After SNX, animals are allowed to recover for two days followed by LNNA in drinking water (20 mg/L) for a further period of 4 weeks. A high salt diet (6%), supplemented in ground chow (see time line Figure 1), is continued throughout the experiment. Progression of renal failure is followed over time by measuring plasma urea, systolic blood pressure and proteinuria. By six weeks after SNX, renal failure has developed. Renal function is measured using 'gold standard' inulin and para-amino hippuric acid (PAH) clearance technology. This model of CKD is characterized by a reduction in glomerular filtration rate (GFR) and effective renal plasma flow (ERPF), hypertension (systolic blood pressure&gt;150 mmHg), proteinuria (&gt; 50 mg/24 hr) and mild uremia (&gt;10 mM). Histological features include tubulo-interstitial damage reflected by inflammation, tubular atrophy and fibrosis and focal glomerulosclerosis leading to massive reduction of healthy glomeruli within the remnant population (&lt;10%). Follow-up until 12 weeks after SNX shows further progression of CKD.

A two-stage method to establish chronic kidney disease (CKD) in the Lewis rat by surgically removing 5/6th of renal mass is described. Combination of the surgical procedure, NOS-inhibition and a high-salt diet leads to a model resembling human CKD, allowing study of causal mechanisms and development of novel therapeutic interventions.

Chronic kidney disease (CKD) is a global problem. Slowing CKD progression is a major health priority. Since CKD is characterized by complex derangements ...

Techniques for Processing Eyes Implanted With a Retinal Prosthesis for Localized Histopathological Analysis

With the recent development of retinal prostheses, it is important to develop reliable techniques for assessing the safety of these devices in preclinical studies. However, the standard fixation, preparation, and automated histology procedures are not ideal. Here we describe new procedures for evaluating the health of the retina directly adjacent to an implant. Retinal prostheses feature electrode arrays in contact with eye tissue. Previous methods have not been able to spatially localize the ocular tissue adjacent to individual electrodes within the array. In addition, standard histological processing often results in gross artifactual detachment of the retinal layers when assessing implanted eyes. Consequently, it has been difficult to assess localized damage, if present, caused by implantation and stimulation of an implanted electrode array. Therefore, we developed a method for identifying and localizing the ocular tissue adjacent to implanted electrodes using a (color-coded) dye marking scheme, and we modified an eye fixation technique to minimize artifactual retinal detachment. This method also rendered the sclera translucent, enabling localization of individual electrodes and specific parts of an implant. Finally, we used a matched control to increase the power of the histopathological assessments. In summary, this method enables reliable and efficient discrimination and assessment of the retinal cytoarchitecture in an implanted eye.

Techniques for visualizing retinal cytoarchitecture directly adjacent to individual electrodes within a retinal stimulator.

With  the recent development of retinal prostheses, it is important to develop  reliable techniques for assessing the safety of these devices in ...

Experimental and Imaging Techniques for Examining Fibrin Clot Structures in Normal and Diseased States

Fibrin is an extracellular matrix protein that is responsible for maintaining the structural integrity of blood clots. Much research has been done on fibrin in the past years to include the investigation of synthesis, structure-function, and lysis of clots. However, there is still much unknown about the morphological and structural features of clots that ensue from patients with disease. In this research study, experimental techniques are presented that allow for the examination of morphological differences of abnormal clot structures due to diseased states such as diabetes and sickle cell anemia. Our study focuses on the preparation and evaluation of fibrin clots in order to assess morphological differences using various experimental assays and confocal microscopy. In addition, a method is also described that allows for continuous, real-time calculation of lysis rates in fibrin clots. The techniques described herein are important for researchers and clinicians seeking to elucidate comorbid thrombotic pathologies such as myocardial infarctions, ischemic heart disease, and strokes in patients with diabetes or sickle cell disease.

In this manuscript, experimental techniques, including blood preparation, confocal microscopy, and lysis rate analysis, to examine the morphological differences between normal and abnormal clot structures due to diseased states are presented.

Fibrin is an extracellular matrix protein that is responsible for maintaining the structural integrity of blood clots. Much research has been done on ...

Optimized Analysis of In Vivo and In Vitro Hepatic Steatosis

Establishing a system of procedures to qualitatively and quantitatively characterize in vivo and in vitro hepatic steatosis is important for metabolic study in the liver. Here, numerous assays are described to comprehensively measure the phenotype and parameters of hepatic steatosis in mouse and hepatocyte models. 
Combining the physiological, histological, and biochemical methods, this system can be used to assess the progress of hepatic steatosis. In vivo, the measurements of body weight and nuclear magnetic resonance (NMR) provide a general understanding of mice in a non-invasive manner. Hematoxylin and Eosin (H&amp;E) and Oil Red O staining determine the histological morphology and lipid deposition of liver tissue under nutrient overload conditions, such as high-fat diet feeding. Next, the total lipid contents are isolated by chloroform/methanol extraction, which are followed by a biochemical analysis for triglyceride and cholesterol. Moreover, mouse primary hepatocytes are treated with high glucose plus insulin to stimulate lipid accumulation, an efficient in vitro model to mimic diet-induced hyperglycemia and hyperinsulinemia in vivo. Then, the lipid deposition is measured by Oil Red O staining and chloroform/methanol extraction. Oil Red O staining determines intuitive hepatic steatotic phenotypes, while the lipid extraction analysis determines the parameters that can be analyzed statistically. The present protocols are of interest to scientists in the fields of fatty liver diseases, insulin resistance, and type 2 diabetes.

Optimized Analysis of In Vivo and In Vitro Hepatic Steatosis

Here, optimized methods to generate in vivo and in vitro models of hepatic steatosis and to analyze the steatotic phenotypes and related physiological parameters are described.

Establishing a system of procedures to qualitatively and quantitatively characterize in vivo and in vitro hepatic steatosis is important for metabolic ...

Synthesis, Characterization, and Application of Superparamagnetic Iron Oxide Nanoprobes for Extrapulmonary Tuberculosis Detection

A molecular imaging probe comprising superparamagnetic iron oxide (SPIO) nanoparticles and Mycobacterium tuberculosis surface antibody (MtbsAb) was synthesized to enhance imaging sensitivity for extrapulmonary tuberculosis (ETB). An SPIO nanoprobe was synthesized and conjugated with MtbsAb. The purified SPIO-MtbsAb nanoprobe was characterized using TEM and NMR. To determine the targeting ability of the probe, SPIO-MtbsAb nanoprobes were incubated with Mtb for in vitro imaging assays and injected into Mtb-inoculated mice for in vivo investigation with magnetic resonance (MR). The contrast enhancement reduction on magnetic resonance imaging (MRI) of Mtb and THP1 cells showed proportional to the SPIO-MtbsAb nanoprobe concentration. After 30 min of intravenous SPIO-MtbsAb nanoprobe injection into Mtb-infected mice, the signal intensity of the granulomatous site was enhanced by 14-fold in the T2-weighted MR images compared with that in mice receiving PBS injection. The MtbsAb nanoprobes can be used as a novel modality for ETB detection.

To improve serological diagnostic tests for Mycobacterium tuberculosis antigens, we developed superparamagnetic iron oxide nanoprobes to detect extrapulmonary tuberculosis.

A molecular imaging probe comprising superparamagnetic iron oxide (SPIO) nanoparticles and Mycobacterium tuberculosis surface antibody (MtbsAb) was ...

Platelet-based Detection of Nitric Oxide in Blood by Measuring VASP Phosphorylation

Platelets are the blood components responsible for proper blood clotting. Their function is highly regulated by various pathways. One of the most potent vasoactive agents, nitric oxide (NO), can also act as a powerful inhibitor of platelet aggregation. Direct NO detection in blood is very challenging due to its high reactivity with cell-free hemoglobin that limits NO half-life to the millisecond range. Currently, NO changes after interventions are only estimated based on measured changes of nitrite and nitrate (members of the nitrate-nitrite-NO metabolic pathway). However precise, these measurements are rather difficult to interpret vis a vis actual NO changes, due to the naturally high baseline nitrite and nitrate levels that are several orders of magnitude higher than expected changes of NO itself. Therefore, the development of direct and simple methods that would allow one to detect NO directly is long overdue. This protocol addresses a potential use of platelets as a highly sensitive NO sensor in blood. It describes initial platelet rich plasma (PRP) and washed platelet preparations and the use of nitrite and deoxygenated red blood cells as NO generators. Phosphorylation of VASP at serine 239 (P-VASPSer239) is used to detect the presence of NO. The fact that VASP protein is highly expressed in platelets and that it is rapidly phosphorylated when NO is present leads to a unique opportunity to use this pathway to directly detect NO presence in blood.

Here, we present a protocol to address the potential use of platelets as a highly sensitive nitric oxide sensor in blood. It describes initial platelet preparation and the use of nitrite and deoxygenated red blood cells as nitric oxide generators.

Platelets are the blood components responsible for proper blood clotting. Their function is highly regulated by various pathways. One of the most potent ...

Cardiac Magnetic Resonance for the Evaluation of Suspected Cardiac Thrombus: Conventional and Emerging Techniques

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;The appearance of a mass on certain magnetic resonance (MR) sequences can help differentiate a thrombus from competing diagnoses such as a tumor. T1 and T2 signal characteristics of a thrombus are related to the evolution of hemoglobin properties. A thrombus typically does not enhance following contrast administration, which also helps differentiation from a tumor. We also highlight the emerging role of T1 mapping in the evaluation of a thrombus, which can add another level of support in diagnosis. Prior to any CMR exam, patient screening and interviews are critical to ensure safety and to optimize patient comfort. Effective communication during the exam between the technologist and the patient promotes proper breath holding technique and higher quality images. Volumetric post processing and structured reporting are helpful to ensure that the radiologist answers the ordering services&#39; question and communicates these results effectively. Optimal pre-MR safety evaluation, CMR exam execution, and post exam processing and reporting allow for delivery of high quality radiological service in the evaluation of a suspected cardiac thrombus.

The goal of this article is to describe how cardiac magnetic resonance can be used for the evaluation and diagnosis of a suspected cardiac thrombus. The method presented will describe data acquisition as well as the pre-procedure and post-procedure protocol.

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;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 ...

Near Infrared Photoimmunotherapy for Mouse Models of Pleural Dissemination

The efficacy of photoimmunotherapy can be evaluated more accurately with an orthotopic mouse model than with a subcutaneous one. A pleural dissemination model can be used for the evaluation of treatment methods for intrathoracic diseases such as lung cancer or malignant pleural mesothelioma.
Near-infrared photoimmunotherapy (NIR-PIT) is a recently developed cancer treatment strategy that combines the specificity of tumor-targeting antibodies with toxicity caused by a photoabsorber (IR700Dye) after exposure to NIR light. The efficacy of NIR-PIT has been reported using various antibodies; however, only a few reports have shown the therapeutic effect of this strategy in an orthotopic model. In the present study, we demonstrate an example of efficacy evaluation of the pleural disseminated lung cancer model, which was treated using NIR-PIT.

Near-infrared photoimmunotherapy (NIR-PIT) is an emerging cancer therapeutic strategy that utilizes an antibody-photoabsorber (IR700Dye) conjugate and NIR light to destroy cancer cells. Here, we present a method to evaluate the antitumor effect of NIR-PIT in a mouse model of pleural disseminated lung cancer and malignant pleural mesothelioma using bioluminescence imaging.

The efficacy of photoimmunotherapy can be evaluated more accurately with an orthotopic mouse model than with a subcutaneous one. A pleural dissemination ...

A Novel Inhalation Mask System to Deliver High Concentrations of Nitric Oxide Gas in Spontaneously Breathing Subjects

Nitric Oxide (NO) is administered as gas for inhalation to induce selective pulmonary vasodilation. It is a safe therapy, with few potential risks even if administered at high concentration. Inhaled NO gas is routinely used to increase systemic oxygenation in different disease conditions. The administration of high concentrations of NO also exerts a virucidal effect in vitro. Owing to its favorable pharmacodynamic and safety profiles, the familiarity in its use by critical care providers, and the potential for a direct virucidal effect, NO is clinically used in patients with coronavirus disease-2019 (COVID-19). Nevertheless, no device is currently available to easily administer inhaled NO at concentrations higher than 80 parts per million (ppm) at various inspired oxygen fractions, without the need for dedicated, heavy, and costly equipment. The development of a reliable, safe, inexpensive, lightweight, and ventilator-free solution is crucial, particularly for the early treatment of non-intubated patients outside of the intensive care unit (ICU) and in a limited-resource scenario. To overcome such a barrier, a simple system for the non-invasive NO gas administration up to 250 ppm was developed using standard consumables and a scavenging chamber. The method has been proven safe and reliable in delivering a specified NO concentration while limiting nitrogen dioxide levels. This paper aims to provide clinicians and researchers with the necessary information on how to assemble or adapt such a system for research purposes or clinical use in COVID-19 or other diseases in which NO administration might be beneficial.

This simple and highly adaptable system device for the inhalation of high-concentration nitric oxide (NO) gas does not require mechanical ventilators, positive pressure, or high gas flows. Standard medical consumables and a snug-fitting mask are used to safely deliver NO gas to spontaneously breathing subjects.

Nitric Oxide (NO) is administered as gas for inhalation to induce selective pulmonary vasodilation. It is a safe therapy, with few potential risks even if ...