Name: fabrication and implantation of miniature dual-element strain gages for measuring in vivo gastrointestinal contractions in rodents.
Uploaded: 2014-09-18T14:00:00
Description: Watch this Scientific Journal Video about Fabrication and Implantation of Miniature Dual-element Strain Gages for Measuring In Vivo Gastrointestinal Contractions in Rodents. at JoVE.com

Research funding was received through the National Institute of Neurological Disorders and Stroke &#160;(NS049177 and NS087834). The authors wish&#160;to acknowledge the intellectual contributions of the late Dr. Paul Bass and his colleagues to the original design of the strain gages; and Carol Tollefsrud for the fabrication and marketing of the strain gages until the cessation of production in 2010 as well as for her insightful correspondence.

All procedures followed National Institutes of Health guidelines and were approved by the Institutional Animal Care and Use Committee at the Penn State Hershey College of Medicine. Rats were housed using common vivarium practices. Note: This protocol uses male Wistar rats &#8805;8 weeks of age and initially weighing 175 - 200 g.
1. Procedures for Fabrication of Strain Gage
<ol>
	<li>Most tooling and components remain available from the original or successor companies and are summarized in <s...

<ol>
	<li>Szarka, L. A., Camilleri, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+measurement+of+gastric+motility.">Methods for measurement of gastric motility.</a> Am. J. Physiol. Gastrointest. Liver Physiol. 296 (3), G461-G475 (2009).</li><li>Pascaud XB, F. A. U., Genton, M. J., Bass, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+miniature+transducer+for+recording+intestinal+motility+in+unrestrained+chronic+rats.">A miniature transducer for recording intestinal motility in unrestrained chronic rats.</a> Am. J. Physiol. Endocrinol. Metab. Gastrointest. Physiol. 4 (5), 532-538 (1978).</li><li>Gourcerol, G., Adelson, D. W., Million, M., Wang, L., Tache, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulation+of+gastric+motility+by+brain-gut+peptides+using+a+novel+non-invasive+miniaturized+pressure+transducer+method+in+anesthetized+rodents.">Modulation of gastric motility by brain-gut peptides using a novel non-invasive miniaturized pressure transducer method in anesthetized rodents.</a> Peptides. 32 (4), 737-746 (2011).</li><li>Am&#233;rico, M. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Validation+of+ACB+in+vitro+and+in+vivo+as+a+biomagnetic+method+for+measuring+stomach+contraction.">Validation of ACB in vitro and in vivo as a biomagnetic method for measuring stomach contraction.</a> Neurogastroenterol. Motil. 22 (12), 1340-1374 (2010).</li><li>Fujitsuka, N., Asakawa, A., Amitani, H., Fujimiya, M., Inui, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+Eighteen+-+Ghrelin+and+Gastrointestinal+Movement.">Chapter Eighteen - Ghrelin and Gastrointestinal Movement.</a> Ghrelin and Gastrointestinal Movement. , 289-301 (2012).</li><li>Monroe, M. J., Hornby, P. J., Partosoedarso, E. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Central+vagal+stimulation+evokes+gastric+volume+changes+in+mice:+a+novel+technique+using+a+miniaturized+barostat.">Central vagal stimulation evokes gastric volume changes in mice: a novel technique using a miniaturized barostat.</a> Neurogastroenterol. Motil. 16 (1), 5-11 (2004).</li><li>Herman, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+noradrenergic+transmission+at+the+dorsal+motor+nucleus+of+the+vagus+involved+in+reflex+control+of+fundus+tone.">Characterization of noradrenergic transmission at the dorsal motor nucleus of the vagus involved in reflex control of fundus tone.</a> Am. J. Physiol. Regul. Integr. Comp. Physiol. 294 (3), 720-729 (2008).</li><li>Gondim, F. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complete+cervical+or+thoracic+spinal+cord+transections+delay+gastric+emptying+and+gastrointestinal+transit+of+liquid+in+awake+rats.">Complete cervical or thoracic spinal cord transections delay gastric emptying and gastrointestinal transit of liquid in awake rats.</a> Spinal Cord. 37 (11), 793-799 (1999).</li><li>Van Bree, S. H. W., 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=Systemic+inflammation+with+enhanced+brain+activation+contributes+to+more+severe+delay+in+postoperative+ileus.">Systemic inflammation with enhanced brain activation contributes to more severe delay in postoperative ileus.</a> Neurogastroenterol. Motil. 25 (8), 540-549 (2013).</li><li>Qualls-Creekmore, E., Tong, M., Holmes, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gastric+emptying+of+enterally+administered+liquid+meal+in+conscious+rats+and+during+sustained+anaesthesia.">Gastric emptying of enterally administered liquid meal in conscious rats and during sustained anaesthesia.</a> Neurogastroenterol. Motil. 22 (2), 181-185 (2010).</li><li>Qualls-Creekmore, E., Tong, M., Holmes, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Time-course+of+recovery+of+gastric+emptying+and+motility+in+rats+with+experimental+spinal+cord+injury.">Time-course of recovery of gastric emptying and motility in rats with experimental spinal cord injury.</a> Neurogastroenterol. Motil. 22 (1), 62 (2010).</li><li>Choi, K. M., 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=Determination+of+gastric+emptying+in+nonobese+diabetic+mice.">Determination of gastric emptying in nonobese diabetic mice.</a> Am. J. Physiol. Gastrointest. Liver Physiol. 293 (5), G1039-G1045 (2007).</li><li>Adelson, D. W., Million, M., Kanamoto, K., Palanca, T., Tache, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coordinated+gastric+and+sphincter+motility+evoked+by+intravenous+CCK-8+as+monitored+by+ultrasonomicrometry+in+rats.">Coordinated gastric and sphincter motility evoked by intravenous CCK-8 as monitored by ultrasonomicrometry in rats.</a> Am. J. Physiol. Gastrointest. Liver Physiol. 286 (2), G321-G332 (2004).</li><li>Xue, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+modulation+of+serotonergic,+cholinergic,+and+nitrergic+pathways+on+murine+fundic+size+and+compliance+measured+by+ultrasonomicrometry.">Effect of modulation of serotonergic, cholinergic, and nitrergic pathways on murine fundic size and compliance measured by ultrasonomicrometry.</a> Am. J. Physiol. Gastrointest. Liver Physiol. 290 (1), G74-G82 (2005).</li><li>Bass, P., Wiley, J. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Contractile+force+transducer+for+recording+muscle+activity+in+unanesthetized+animals.">Contractile force transducer for recording muscle activity in unanesthetized animals.</a> J. Appl. Physiol. 32 (4), 567-570 (1972).</li><li>Holmes, G. M., Browning, K. N., Tong, M., Qualls-Creekmore, E., Travagli, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vagally+mediated+effects+of+glucagon-like+peptide+1:+in+vitro+and+in+vivo+gastric+actions.">Vagally mediated effects of glucagon-like peptide 1: in vitro and in vivo gastric actions.</a> J. Physiol. 587 (19), 4749-4759 (2009).</li><li>Tong, M., Qualls-Creekmore, E., Browning, K. N., Travagli, R. A., Holmes, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+spinal+cord+injury+in+rats+diminishes+vagally-mediated+gastric+responses+to+cholecystokinin-8s.">Experimental spinal cord injury in rats diminishes vagally-mediated gastric responses to cholecystokinin-8s.</a> Neurogastroenterol. Motil. 23 (2), e69-e79 (2011).</li><li>Miyano, 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=The+role+of+the+vagus+nerve+in+the+migrating+motor+complex+and+ghrelin-+and+motilin-induced+gastric+contraction+in+suncus.">The role of the vagus nerve in the migrating motor complex and ghrelin- and motilin-induced gastric contraction in suncus.</a> PLoS ONE. 8 (5), e64777 (2013).</li><li>Holmes, G. M., Rogers, R. C., Bresnahan, J. C., Beattie, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thyrotropin-releasing+hormone+(TRH)+and+CNS+regulation+of+anorectal+motility+in+the+rat.">Thyrotropin-releasing hormone (TRH) and CNS regulation of anorectal motility in the rat.</a> J Auton. Nerv. Syst. 56, 8-14 (1995).</li><li>Ormsbee, H. S., Bass, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gastroduodenal+motor+gradients+in+the+dog+after+pyloroplasty.">Gastroduodenal motor gradients in the dog after pyloroplasty.</a> Am. J. Physiol. 230, 389-397 (1976).</li><li>Fukuda, H., 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=Impaired+gastric+motor+activity+after+abdominal+surgery+in+rats.">Impaired gastric motor activity after abdominal surgery in rats.</a> Neurogastroenterol. Motil. 17 (2), 245-250 (2005).</li><li>Browning, K. N., Babic, T., Holmes, G. M., Swartz, E., Travagli, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+critical+re-evaluation+of+the+specificity+of+action+of+perivagal+capsaicin.">A critical re-evaluation of the specificity of action of perivagal capsaicin.</a> J. Physiol. 591 (6), 1563-1580 (2013).</li></ol>

The procedures presented here allow individual laboratories to fabricate sensitive miniature strain gages for biological applications including, but not limited to, gastrointestinal motility in small laboratory animals. Since the commercial manufacture of these strain gages has ceased, laboratories investigating gastrointestinal function are limited to other techniques which may not permit the full range of experimental applications that are available. This report provides an updated and more detailed description of prev...

Experimental studies that record in vivo gastrointestinal (GI) motility across a number of experimental conditions remain a powerful tool for understanding the underlying normal and pathophysiological processes necessary for nutrient homeostasis. Traditionally, numerous experimental methodologies, some with similarities to those found in clinical practice 1, have been employed to directly quantify changes in GI contraction rate 2-5, intraluminal pressure 6, 7, or the GI transit of non-absorbable markers 8, 9 or stable isotopes 10-12. Each of these techniques has unique advantages and disadvantages, which have been addressed previously in the literature. For example, the utility of balloon manometry to quantify pressure changes has been questioned due to the inherent compliance of the balloon material while gastrointestinal recovery of nonabsorbable markers requires euthanizing the experimental animal for a single data point. Recently, the application and validation of a miniaturized arterial pressure catheter has been reported that offers a non-surgical method for monitoring gastric contractility in rats and mice 3. While an orogastrically placed pressure transducer effectively eliminates confounding variables on gastrointestinal function by avoiding invasive surgical procedures, such an approach is only suitable for anesthetized preparations. Furthermore, the lack of visual guidance does not permit consistent placement of the transducer within specific regions of the stomach. As such, this application is restricted to the stomach or colon since visualization, coupled with the relatively stiff transducer wire, within the duodenum or ileum is not an option.
Similarly, the biomagnetic alternate current biosusceptometry (ACB) technique has been validated for GI contraction analysis 4. While the ACB technique provides a noninvasive approach for measuring gastrointestinal contractions, ACB suffers from a similar limitation in that the use of ingested magnetic detection media does not permit precise recording of specific regions of the GI tract. This limitation can be overcome through the surgical implantation of magnetic markers. Nonetheless, the ACB technique necessitates that the animal be anesthetized for data collection.
Ultrasonomicrometry has been employed in some GI studies 13, 14 in order to take advantage of the small size, spatial, and temporal advantages of piezoelectric crystal transmitter/receivers. Waves of gastric smooth muscle contraction are not a high-frequency event and occur at a rate of approximately 3 - 5 cycles/min. Therefore, the temporal advantages of sonomicrometry may be unnecessary to justify the cost. Furthermore, while linear motion is accurately measured with sonomicrometry, limitations have been presented regarding accurate gastrointestinal data interpretation that may result from implanting an insufficient number of crystals 14.
Based upon the original designs of Bass and colleagues 2, 15 this visualized protocol more fully documents the step-by-step fabrication and experimental application of miniature, dual element strain gages that possess high sensitivity and flexibility for recording smooth muscle contractions along the entire GI tract. The dimensions of the strain gage elements are suitable for any rodent application since sensitivity and size of the finished strain gage are most dependent upon the silicone sheets encapsulating the elements. These strain gages are readily adapted for acute and chronic application in anesthetized and freely behaving laboratory animal models thereby providing a single technique for quantifying smooth muscle contractions.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Strain gage element</td>
			<td>Micro-Measurements (Vishay Product Group)</td>
			<td>EA-06-031-350</td>
			<td>&#160;Linear pattern, foil, stress analysis strain gage (2 required) 
			<a href="http://www.vishaypg.com/micro-measurements/">www.vishaypg.com/micro-measurements/</a> 
			or 
			<a href="http://www.vishaypg.com/docs/11070/031ce.pdf">http://www.vishaypg.com/docs/11070/031ce.pdf</a></td>
		</tr>
		<tr>
			<td>epoxy-phenolic adhesive</td>
			<td>M-bond 610</td>
			<td>General purpose adhesive for bonding strain gage elements</td>
			<td><a href="http://www.vishaypg.com/docs/11024/wirecable.pdf">http://www.vishaypg.com/docs/11024/wirecable.pdf</a></td>
		</tr>
		<tr>
			<td>3 conductor insulated wire</td>
			<td>336-FTE</td>
			<td>Fine gage, flexible general purpose wire</td>
			<td><a href="http://www.vishaypg.com/docs/11024/wirecable.pdf">http://www.vishaypg.com/docs/11024/wirecable.pdf</a></td>
		</tr>
		<tr>
			<td>Flux and rosin solvent kit</td>
			<td>FAR-2 M-Flux AR kit</td>
			<td>Liquid solder flux</td>
			<td><a href="http://www.vishaypg.com/docs/11023/soldacce.pdf">http://www.vishaypg.com/docs/11023/soldacce.pdf</a></td>
		</tr>
		<tr>
			<td>Solder</td>
			<td>361A-20R-25</td>
			<td>Optimized and recommended for strain gage applications</td>
			<td><a href="http://www.vishaypg.com/docs/11023/soldacce.pdf">http://www.vishaypg.com/docs/11023/soldacce.pdf</a></td>
		</tr>
		<tr>
			<td>Gold socket connector</td>
			<td>PlasticsOne</td>
			<td>E363/0</td>
			<td>Socket contact for electrode pedestal 
			<a href="http://www.plastics1.com/PCR/Catalog/Item.php?item=407">http://www.plastics1.com/PCR/Catalog/Item.php?item=407</a></td>
		</tr>
		<tr>
			<td>Electrode pedestal</td>
			<td>MS363</td>
			<td>Secure platform for wire contacts</td>
			<td><a href="http://www.plastics1.com/PCR/Catalog/Item.php?item=499">http://www.plastics1.com/PCR/Catalog/Item.php?item=499</a></td>
		</tr>
		<tr>
			<td>6-wire cable</td>
			<td>363 PLUG W/VINYL SL/6</td>
			<td>Pre-fabricated vinyl-coated cable (in customized lengths) with plug adaptor to match electrode pedestal and tinned solder lugs on terminal end</td>
			<td></td>
		</tr>
		<tr>
			<td>Silicone rubber casting compound</td>
			<td>EIS electrical products</td>
			<td>Elan Tron E211</td>
			<td>Potting medium for gage/wire solder joints 
			<a href="http://www.eis-inc.com/">http://www.eis-inc.com</a></td>
		</tr>
		<tr>
			<td>HOTweezers</td>
			<td>Meisei Corporation</td>
			<td>Model 4B</td>
			<td>Wire insulation strippers 
			<a href="http://www.impexron.us/">http://www.impexron.us</a></td>
		</tr>
		<tr>
			<td>Soldering station</td>
			<td>Weller (Apex Tool Group)</td>
			<td>WES 51</td>
			<td>High quality soldering equipment 
			<a href="http://www.apexhandtools.com/weller/index.cfm">http://www.apexhandtools.com/weller/index.cfm</a></td>
		</tr>
		<tr>
			<td>Available through http://www.eis-inc.com or http://www.amazon.com</td>
		</tr>
		<tr>
			<td>Silicone sheet</td>
			<td>Trelleborg Sealing Solutions Northborough-Life Sciences</td>
			<td>Pharmelast 20-20</td>
			<td>Encapsulating strain gauge elements 
			10 B Forbes Road Northborough, MA 01532 (800) 634-2000</td>
		</tr>
		<tr>
			<td>Amplifier</td>
			<td>Experimetria Ltd</td>
			<td>AMP-01-SG</td>
			<td> 
			<a href="http://experimetria.com/Biological_amplifiers.php">http://experimetria.com/Biological_amplifiers.php</a></td>
		</tr>
	</tbody>
</table>

fabrication and implantation of miniature dual-element strain gages for measuring in vivo gastrointestinal contractions in rodents.

Gastrointestinal dysfunction remains a major cause of morbidity and mortality. Indeed, gastrointestinal (GI) motility in health and disease remains an area of productive research with over 1,400 published animal studies in just the last 5 years. Numerous techniques have been developed for quantifying smooth muscle activity of the stomach, small intestine, and colon. In vitro and ex vivo techniques offer powerful tools for mechanistic studies of GI function, but outside the context of the integrated systems inherent to an intact organism. Typically, measuring in vivo smooth muscle contractions of the stomach has involved an anesthetized preparation coupled with the introduction of a surgically placed pressure sensor, a static pressure load such as a mildly inflated balloon or by distending the stomach with fluid under barostatically-controlled feedback. Yet many of these approaches present unique disadvantages regarding both the interpretation of results as well as applicability for in vivo use in conscious experimental animal models. The use of dual element strain gages that have been affixed to the serosal surface of the GI tract has offered numerous experimental advantages, which may continue to outweigh the disadvantages. Since these gages are not commercially available, this video presentation provides a detailed, step-by-step guide to the fabrication of the current design of these gages. The strain gage described in this protocol is a design for recording gastric motility in rats. This design has been modified for recording smooth muscle activity along the entire GI tract and requires only subtle variation in the overall fabrication. Representative data from the entire GI tract are included as well as discussion of analysis methods, data interpretation and presentation.

Representative data from a Thiobutabarbital-anesthetized rat are shown in Figure 2. The top trace represents the gastric corpus contractions from the rat during the brainstem administration of thyrotropin releasing hormone (TRH, 100 pmol), a known motility-enhancing peptide 3, 19. It shows baseline contractions prior to the increase in phasic gastric smooth muscle activity. Note: Analysis of these peaks in gastric contractions follow the original formula devised by Ormsby and Bass 20</sup...

Watch this Scientific Journal Video about Fabrication and Implantation of Miniature Dual-element Strain Gages for Measuring In Vivo Gastrointestinal Contractions in Rodents. at JoVE.com

Fabrication and Implantation of Miniature Dual-element Strain Gages for Measuring In Vivo Gastrointestinal Contractions in Rodents.

The in vivo measurement of smooth muscle contractions along the gastrointestinal tract of laboratory animals remains a powerful, though underutilized, technique. Flexible, dual element strain gages are not commercially available and require fabrication. This protocol describes the construction of reliable, inexpensive strain gages for acute or chronic implantation in rodents.

Fabrication and Implantation of Miniature Dual-element Strain Gages for Measuring In Vivo Gastrointestinal Contractions in Rodents.

Gastrointestinal dysfunction remains a major cause of morbidity and mortality. Indeed, gastrointestinal (GI) motility in health and disease remains an ...

fabrication-implantation-miniature-dual-element-strain-gages-for

Research

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Bioengineering

Fabrication of Electrochemical-DNA Biosensors for the Reagentless Detection of Nucleic Acids, Proteins and Small Molecules

As medicine is currently practiced, doctors send specimens to a central laboratory for testing and thus must wait hours or days to 
receive the results. Many patients would be better served by rapid, bedside tests. To this end our laboratory and others have developed a versatile, reagentless 
biosensor platform that supports the quantitative, reagentless, electrochemical detection of nucleic acids (DNA, RNA), proteins (including antibodies) and small 
molecules analytes directly in unprocessed clinical and environmental samples. In this video, we demonstrate the preparation and use of several biosensors in this 
"E-DNA" class. In particular, we fabricate and demonstrate sensors for the detection of a target DNA sequence in a polymerase chain reaction mixture, an HIV-specific antibody and the drug cocaine. The preparation procedure requires only three hours of hands-on effort followed by an overnight incubation, and their use requires only minutes.

"E-DNA" sensors, reagentless, electrochemical biosensors that perform well even when challenged directly in blood and other complex matrices, have been adapted to the detection of a wide range of nucleic acid, protein and small molecule analytes. Here we present a general procedure for the fabrication and use of such sensors.

As medicine is currently practiced, doctors send specimens to a central laboratory for testing and thus must wait hours or days to 
receive the results. ...

Surgical Technique for the Implantation of Tissue Engineered Vascular Grafts and Subsequent In Vivo Monitoring

The development of Tissue Engineered Vessels (TEVs) is advanced by the ability to routinely and effectively implant TEVs (4-5 mm in diameter) into a large animal model. A step by-step protocol for inter-positional placement of the TEV and real-time digital assessment of the TEV and native carotid arteries is described here. In vivo monitoring is made possible by the implantation of flow probes, catheters and ultrasonic crystals (capable of recording dynamic diameter changes of implanted TEVs and native carotid arteries) at the time of surgery. Once implanted, researchers can calculate arterial blood flow patterns, invasive blood pressure and artery diameter yielding parameters such as pulse wave velocity, augmentation index, pulse pressures and compliance. Data acquisition is accomplished using a single computer program for analysis throughout the duration of the experiment. Such invaluable data provides insight into TEV matrix remodeling, its resemblance to native/sham controls and overall TEV performance in vivo.

Surgical Technique for the Implantation of Tissue Engineered Vascular Grafts and Subsequent In Vivo Monitoring

A step-by-step protocol for the inter-positional placement of Tissue Engineered Vessels (TEVs) into the carotid artery of a sheep using end-to-end anastomosis and real-time digital assessment in vivo until animal sacrifice.

The development of Tissue Engineered Vessels (TEVs) is advanced by the ability to routinely and effectively implant TEVs (4-5 mm in diameter) into a large ...

Culturing Mouse Cardiac Valves in the Miniature Tissue Culture System

Heart valve disease is a major burden in the Western world and no effective treatment is available. This is mainly due to a lack of knowledge of the molecular, cellular and mechanical mechanisms underlying the maintenance and/or loss of the valvular structure. 
Current models used to study valvular biology include in vitro cultures of valvular endothelial and interstitial cells. Although, in vitro culturing models provide both cellular and molecular mechanisms, the mechanisms involved in the 3D-organization of the valve remain unclear. While in vivo models have provided insight into the molecular mechanisms underlying valvular development, insight into adult valvular biology is still elusive. 
In order to be able to study the regulation of the valvular 3D-organization on tissue, cellular and molecular levels, we have developed the Miniature Tissue Culture System. In this ex vivo flow model the mitral or the aortic valve is cultured in its natural position in the heart. The natural configuration and composition of the leaflet are maintained allowing the most natural response of the valvular cells to stimuli. The valves remain viable and are responsive to changing environmental conditions. This MTCS may provide advantages on studying questions including but not limited to, how does the 3D organization affect valvular biology, what factors affect 3D organization of the valve, and which network of signaling pathways regulates the 3D organization of the valve.

Here, we present an ex vivo flow model in which murine cardiac valves can be cultured allowing the study of the biology of the valve.

Heart valve disease is a major burden in the Western world and no effective treatment is available. This is mainly due to a lack of knowledge of the ...

Gradient Strain Chip for Stimulating Cellular Behaviors in Cell-laden Hydrogel

Artificial guidance for cellular alignment is a hot topic in the field of tissue engineering. Most of the previous research has investigated single strain-induced cellular alignment on a cell-laden hydrogel by using complex experimental processes and mass controlling systems, which are usually associated with contamination issues. Thus, in this article, we propose a simple approach to building a gradient static strain using a fluidic chip with a plastic PDMS cover and a UV transparent glass substrate for the stimulation of cellular behavior in a 3D hydrogel. Overloading photo-patternable cell prepolymer in the fluidic chamber can generate a convex curved PDMS membrane on the cover. After UV crosslinking, through a concentric circular micropattern under the curved PDMS membrane, and buffer washing, a microenvironment for investigating cell behaviors under a variety of gradient strains is self-established in a single fluidic chip, without external instruments. NIH3T3 cells were demonstrated after observing the change in the cellular alignment trend under geometry guidance, in cooperation with strain stimulation, which varied from 15 - 65% on hydrogels. After a 3-day incubation, the hydrogel geometry dominated the cell alignment under low compressive strain, where cells aligned along the hydrogel elongation direction under high compressive strain. Between these, the cells showed random alignment due to the dissipation of the radical guidance of hydrogel elongation and the geometry guidance of the patterned hydrogel.

This article introduces a simple approach to providing non-continuous gradient static strains on a concentric cell-laden hydrogel to regulate cell alignment for tissue engineering.

Artificial guidance for cellular alignment is a hot topic in the field of tissue engineering. Most of the previous research has investigated single ...

Rigid Embedding of Fixed and Stained, Whole, Millimeter-Scale Specimens for Section-free 3D Histology by Micro-Computed Tomography

For over a hundred years, the histological study of tissues has been the gold standard for medical diagnosis because histology allows all cell types in every tissue to be identified and characterized. Our laboratory is actively working to make technological advances in X-ray micro-computed tomography (micro-CT) that will bring the diagnostic power of histology to the study of full tissue volumes at cellular resolution (i.e., an X-ray Histo-tomography modality). Toward this end, we have made targeted improvements to the sample preparation pipeline. One key optimization, and the focus of the present work, is a straightforward method for rigid embedding of fixed and stained millimeter-scale samples. Many of the published methods for sample immobilization and correlative micro-CT imaging rely on placing the samples in paraffin wax, agarose, or liquids such as alcohol. Our approach extends this work with custom procedures and the design of a 3-dimensional printable apparatus to embed the samples in an acrylic resin directly into polyimide tubing, which is relatively transparent to X-rays. Herein, sample preparation procedures are described for the samples from 0.5 to 10 mm in diameter, which would be suitable for whole zebrafish larvae and juveniles, or other animals and tissue samples of similar dimensions. As proof of concept, we have embedded the specimens from Danio, Drosophila, Daphnia, and a mouse embryo; representative images from 3-dimensional scans for three of these samples are shown. Importantly, our methodology leads to multiple benefits including rigid immobilization, long-term preservation of laboriously-created resources, and the ability to re-interrogate samples.

We developed protocols and designed a custom apparatus to enable embedding of millimeter-scale specimens. We present sample preparation procedures with an emphasis on embedding in acrylic resin and polyimide tubing to achieve rigid immobilization and long-term storage of specimens for the interrogation of tissue architecture and cell morphology by micro-CT.

For over a hundred years, the histological study of tissues has been the gold standard for medical diagnosis because histology allows all cell types in ...

High-resolution Imaging of Nuclear Dynamics in Live Cells under Uniaxial Tensile Strain

Extracellular mechanical strain is known to elicit cell phenotypic responses and has physiological relevance in several tissue systems. To capture the effect of applied extracellular tensile strain on cell populations in vitro via biochemical assays, a device has previously been designed which can be fabricated simply and is small enough to fit inside tissue culture incubators, as well as on top of microscope stages. However, the previous design of the polydimethylsiloxane substratum did not allow high-resolution subcellular imaging via oil-immersion objectives. This work describes a redesigned geometry of the polydimethylsiloxane substratum and a customized imaging setup that together can facilitate high-resolution subcellular imaging of live cells while under applied strain. This substratum can be used with the same, earlier designed device and, hence, has the same advantages as listed above, in addition to allowing high-resolution optical imaging. The design of the polydimethylsiloxane substratum can be improved by incorporating a grid which will facilitate tracking the same cell before and after the application of strain. Representative results demonstrate high-resolution time-lapse imaging of fluorescently labeled nuclei within strained cells captured using the method described here. These nuclear dynamics data give insights into the mechanism by which applied tensile strain promotes differentiation of oligodendrocyte progenitor cells.&#160;

Using a previously designed device to apply mechanical strain to adherent cells, this paper describes a redesigned substratum geometry and a customized apparatus for high-resolution single-cell imaging of strained cells with a 100x oil immersion objective.

Extracellular mechanical strain is known to elicit cell phenotypic responses and has physiological relevance in several tissue systems. To capture the ...

Fabrication of Ti3C2 MXene Microelectrode Arrays for In Vivo Neural Recording

Implantable microelectrode technologies have been widely used to elucidate neural dynamics at the microscale to gain a deeper understanding of the neural underpinnings of brain disease and injury. As electrodes are miniaturized to the scale of individual cells, a corresponding rise in the interface impedance limits the quality of recorded signals. Additionally, conventional electrode materials are stiff, resulting in a significant mechanical mismatch between the electrode and the surrounding brain tissue, which elicits an inflammatory response that eventually leads to a degradation of the device performance. To address these challenges, we have developed a process to fabricate flexible microelectrodes based on Ti3C2 MXene, a recently discovered nanomaterial that possesses remarkably high volumetric capacitance, electrical conductivity, surface functionality, and processability in aqueous dispersions. Flexible arrays of Ti3C2 MXene microelectrodes have remarkably low impedance due to the high conductivity and high specific surface area of the Ti3C2 MXene films, and they have proven to be exquisitely sensitive for recording neuronal activity. In this protocol, we describe a novel method for micropatterning Ti3C2 MXene into microelectrode arrays on flexible polymeric substrates and outline their use for in vivo micro-electrocorticography recording. This method can easily be extended to create MXene electrode arrays of arbitrary size or geometry for a range of other applications in bioelectronics and it can also be adapted for use with other conductive inks besides Ti3C2 MXene. This protocol enables simple and scalable fabrication of microelectrodes from solution-based conductive inks, and specifically allows harnessing the unique properties of hydrophilic Ti3C2 MXene to overcome many of the barriers that have long hindered the widespread adoption of carbon-based nanomaterials for high-fidelity neural microelectrodes.

Fabrication of Ti3C2 MXene Microelectrode Arrays for In Vivo Neural Recording

We describe here a method for fabricating Ti3C2 MXene microelectrode arrays and utilizing them for in vivo neural recording.

Implantable microelectrode technologies have been widely used to elucidate neural dynamics at the microscale to gain a deeper understanding of the neural ...

High Throughput Yeast Strain Phenotyping with Droplet-Based RNA Sequencing

The powerful tools available to edit yeast genomes have made this microbe a valuable platform for engineering. While it is now possible to construct libraries of millions of genetically distinct strains, screening for a desired phenotype remains a significant obstacle. With existing screening techniques, there is a tradeoff between information output and throughput, with high-throughput screening typically being performed on one product of interest. Therefore, we present an approach to accelerate strain screening by adapting single cell RNA sequencing to isogenic picoliter colonies of genetically engineered yeast strains. To address the unique challenges of performing RNA sequencing on yeast cells, we culture isogenic yeast colonies within hydrogels and spheroplast prior to performing RNA sequencing. The RNA sequencing data can be used to infer yeast phenotypes and sort out engineered pathways. The scalability of our method addresses a critical obstruction in microbial engineering.

A bottleneck in the &#8216;design-build-test&#8217; cycle of microbial engineering is the speed at which we can perform functional screens of strains. We describe a high-throughput method for strain screening applied to hundreds to thousands of yeast cells per experiment that utilizes droplet-based RNA sequencing.

The powerful tools available to edit yeast genomes have made this microbe a valuable platform for engineering. While it is now possible to construct ...

Measuring 3D In-vivo Shoulder Kinematics using Biplanar Videoradiography

The shoulder is one of the human body's most complex joint systems, with motion occurring through the coordinated actions of four individual joints, multiple ligaments, and approximately 20 muscles. Unfortunately, shoulder pathologies (e.g., rotator cuff tears, joint dislocations, arthritis) are common, resulting in substantial pain, disability, and decreased quality of life. The specific etiology for many of these pathologic conditions is not fully understood, but it is generally accepted that shoulder pathology is often associated with altered joint motion. Unfortunately, measuring shoulder motion with the necessary level of accuracy to investigate motion-based hypotheses is not trivial. However, radiographic-based motion measurement techniques have provided the advancement necessary to investigate motion-based hypotheses and provide a mechanistic understanding of shoulder function. Thus, the purpose of this article is to describe the approaches for measuring shoulder motion using a custom biplanar videoradiography system. The specific objectives of this article are to describe the protocols to acquire biplanar videoradiographic images of the shoulder complex, acquire CT scans, develop 3D bone models, locate anatomical landmarks, track the position and orientation of the humerus, scapula, and torso from the biplanar radiographic images, and calculate the kinematic outcome measures. In addition, the article will describe special considerations unique to the shoulder when measuring joint kinematics using this approach.

Biplane videoradiography can quantify shoulder kinematics with a high degree of accuracy. The protocol described herein was specifically designed to track the scapula, humerus, and the ribs during planar humeral elevation, and outlines the procedures for data collection, processing, and analysis. Unique considerations for data collection are also described.

The shoulder is one of the human body's most complex joint systems, with motion occurring through the coordinated actions of four individual joints, ...

A Micropatterning Assay for Measuring Cell Chirality

Chirality is an intrinsic cellular property, which depicts the asymmetry in terms of polarization along the left-right axis of the cell. As this unique property attracts increasing attention due to its important roles in both development and disease, a standardized quantification method for characterizing cell chirality would advance research and potential applications. In this protocol, we describe a multicellular chirality characterization assay that utilizes micropatterned arrays of cells. Cellular micropatterns are fabricated on titanium/gold-coated glass slides via microcontact printing. After seeding on the geometrically defined (e.g., ring-shaped), protein-coated islands, cells directionally migrate and form a biased alignment toward either the clockwise or the counterclockwise direction, which can be automatically analyzed and quantified by a custom-written MATLAB program. Here we describe in detail the fabrication of micropatterned substrates, cell seeding, image collection, and data analysis and show representative results obtained using the NIH/3T3 cells. This protocol has previously been validated in multiple published studies and is an efficient and reliable tool for studying cell chirality in vitro.

We present a protocol for determining multicellular chirality in vitro, using the micropatterning technique. This assay allows for automatic quantification of the left-right biases of various types of cells and can be used for screening purposes.

Chirality is an intrinsic cellular property, which depicts the asymmetry in terms of polarization along the left-right axis of the cell. As this unique ...