Name: assessment of bone fracture healing using micro-computed tomography
Uploaded: 2022-12-09T13:30:00
Description: Watch this Scientific Journal Video about Assessment of Bone Fracture Healing Using Micro-Computed Tomography at JoVE.com

This work was supported by National Institutes of Health (NIH) R01 DK121327 to R.A.E and R01 AR071968 to F.K.

The following protocol was developed to characterize long-bone healing callus harvested from euthanized mice. However, most of the steps can be applied to rats and also used for in vivo scanning of fractured bones. The protocol describes a particular &#181;CT system and specific image processing, analysis, and visualization software (see Table of Materials), yet the methodology is generally applicable to other scanners and software. The protocol was approved by the Institutional Animal Care and ...

<ol>
	<li>R&#252;egsegger, P., Koller, B., M&#252;ller, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+microtomographic+system+for+the+nondestructive+evaluation+of+bone+architecture.">A microtomographic system for the nondestructive evaluation of bone architecture.</a> Calcified Tissue International. 58 (1), 24-29 (1996).</li><li>M&#252;ller, R., 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=Morphometric+analysis+of+human+bone+biopsies:+a+quantitative+structural+comparison+of+histological+sections+and+micro-computed+tomography.">Morphometric analysis of human bone biopsies: a quantitative structural comparison of histological sections and micro-computed tomography.</a> Bone. 23 (1), 59-66 (1998).</li><li>Waarsing, J. 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=Detecting+and+tracking+local+changes+in+the+tibiae+of+individual+rats:+a+novel+method+to+analyse+longitudinal+in+vivo+micro-CT+data.">Detecting and tracking local changes in the tibiae of individual rats: a novel method to analyse longitudinal in vivo micro-CT data.</a> Bone. 34 (1), 163-169 (2004).</li><li>Boyd, S. K., Davison, P., M&#252;ller, R., Gasser, 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=Monitoring+individual+morphological+changes+over+time+in+ovariectomized+rats+by+in+vivo+micro-computed+tomography.">Monitoring individual morphological changes over time in ovariectomized rats by in vivo micro-computed tomography.</a> Bone. 39 (4), 854-862 (2006).</li><li>Christiansen, B. A. <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+micro-computed+tomography+voxel+size+and+segmentation+method+on+trabecular+bone+microstructure+measures+in+mice.">Effect of micro-computed tomography voxel size and segmentation method on trabecular bone microstructure measures in mice.</a> Bone Reports. 5, 136-140 (2016).</li><li>Holdsworth, D. W., Thornton, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micro-CT+in+small+animal+and+specimen+imaging.">Micro-CT in small animal and specimen imaging.</a> Trends in Biotechnology. 20 (8), 34-39 (2002).</li><li>Schambach, S. J., Bag, S., Schilling, L., Groden, C., Brockmann, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+micro-CT+in+small+animal+imaging.">Application of micro-CT in small animal imaging.</a> Methods. 50 (1), 2-13 (2010).</li><li>Bouxsein, M. 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=Guidelines+for+assessment+of+bone+microstructure+in+rodents+using+micro-computed+tomography.">Guidelines for assessment of bone microstructure in rodents using micro-computed tomography.</a> Journal of Bone and Mineral Research. 25 (7), 1468-1486 (2010).</li><li>Morgan, E. 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=Micro-computed+tomography+assessment+of+fracture+healing:+Relationships+among+callus+structure,+composition,+and+mechanical+function.">Micro-computed tomography assessment of fracture healing: Relationships among callus structure, composition, and mechanical function.</a> Bone. 44 (2), 335-344 (2009).</li><li>O'Neill, K. R., 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=Micro-computed+tomography+assessment+of+the+progression+of+fracture+healing+in+mice.">Micro-computed tomography assessment of the progression of fracture healing in mice.</a> Bone. 50 (6), 1357-1367 (2012).</li><li>Bissinger, O., 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=Fully+automated+segmentation+of+callus+by+micro-CT+compared+to+biomechanics.">Fully automated segmentation of callus by micro-CT compared to biomechanics.</a> Journal of Orthopaedic Surgery and Research. 12 (1), 108 (2017).</li><li>Brown, M. 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=Delayed+fracture+healing+and+increased+callus+adiposity+in+a+C57BL/6J+murine+model+of+obesity-associated+type+2+diabetes+mellitus.">Delayed fracture healing and increased callus adiposity in a C57BL/6J murine model of obesity-associated type 2 diabetes mellitus.</a> PLOS One. 9 (6), 99656 (2014).</li><li>Khajuria, D. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aberrant+structure+of+fibrillar+collagen+and+elevated+levels+of+advanced+glycation+end+products+typify+delayed+fracture+healing+in+the+diet-induced+obesity+mouse+model.">Aberrant structure of fibrillar collagen and elevated levels of advanced glycation end products typify delayed fracture healing in the diet-induced obesity mouse model.</a> Bone. 137, 115436 (2020).</li><li>Sigurdsen, U., Reikeras, O., Hoiseth, A., Utvag, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Correlations+between+strength+and+quantitative+computed+tomography+measurement+of+callus+mineralization+in+experimental+tibial+fractures.">Correlations between strength and quantitative computed tomography measurement of callus mineralization in experimental tibial fractures.</a> Clinical Biomechanics. 26 (1), 95-100 (2011).</li><li>Duvall, C. L., Taylor, W. R., Weiss, D., Wojtowicz, A. M., Guldberg, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impaired+angiogenesis,+early+callus+formation,+and+late+stage+remodeling+in+fracture+healing+of+osteopontin-deficient+mice.">Impaired angiogenesis, early callus formation, and late stage remodeling in fracture healing of osteopontin-deficient mice.</a> Journal of Bone and Mineral Research. 22 (2), 286-297 (2007).</li><li>Gerstenfeld, L. 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=Comparison+of+effects+of+the+bisphosphonate+alendronate+versus+the+RANKL+inhibitor+denosumab+on+murine+fracture+healing.">Comparison of effects of the bisphosphonate alendronate versus the RANKL inhibitor denosumab on murine fracture healing.</a> Journal of Bone and Mineral Research. 24 (2), 196-208 (2009).</li><li>Alentado, V. J., 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+the+modified+radiographic+union+score+for+tibia+fractures+(mRUST)+in+murine+femoral+fractures.">Validation of the modified radiographic union score for tibia fractures (mRUST) in murine femoral fractures.</a> Frontiers in Endocrinology. 13, 911058 (2022).</li><li>Yu, K. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancement+of+impaired+MRSA-infected+fracture+healing+by+combinatorial+antibiotics+and+modulation+of+sustained+inflammation.">Enhancement of impaired MRSA-infected fracture healing by combinatorial antibiotics and modulation of sustained inflammation.</a> Journal of Bone and Mineral Research. 37 (1), 1352-1365 (2022).</li><li>Nyman, J. 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=Quantitative+measures+of+femoral+fracture+repair+in+rats+derived+by+micro-computed+tomography.">Quantitative measures of femoral fracture repair in rats derived by micro-computed tomography.</a> Journal of Biomechanics. 42 (7), 891-897 (2009).</li><li>Fiset, 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=Experimental+validation+of+the+radiographic+union+score+for+tibial+fractures+(RUST)+using+micro-computed+tomography+scanning+and+biomechanical+testing+in+an+in-vivo+rat+model.">Experimental validation of the radiographic union score for tibial fractures (RUST) using micro-computed tomography scanning and biomechanical testing in an in-vivo rat model.</a> The Journal of Bone and Joint Surgery. 100 (21), 1871-1878 (2018).</li><li>Shefelbine, S. J., 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=Prediction+of+fracture+callus+mechanical+properties+using+micro-CT+images+and+voxel-based+finite+element+analysis.">Prediction of fracture callus mechanical properties using micro-CT images and voxel-based finite element analysis.</a> Bone. 36 (3), 480-488 (2005).</li><li>Liu, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Glucocorticoid-induced+delayed+fracture+healing+and+impaired+bone+biomechanical+properties+in+mice.">Glucocorticoid-induced delayed fracture healing and impaired bone biomechanical properties in mice.</a> Clinical Interventions in Aging. 13, 1465-1474 (2018).</li><li>Watson, P. J., Fitton, L. C., Meloro, C., Fagan, M. J., Gr&#246;ning, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+adaptation+of+trabecular+bone+morphology+in+the+mammalian+mandible.">Mechanical adaptation of trabecular bone morphology in the mammalian mandible.</a> Scientific Reports. 8 (1), 7277 (2018).</li><li>Nie, C., Wang, Z., Liu, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+depression+on+fracture+healing+and+osteoblast+differentiation+in+rats.">The effect of depression on fracture healing and osteoblast differentiation in rats.</a> Neuropsychiatric Disease and Treatment. 14, 1705-1713 (2018).</li></ol>

The purpose of this study is to describe a detailed protocol for &#181;CT analysis with the goal of accurate quantification of the 3D mineralized callus structure, which is often fundamental in bone and fracture healing studies. The protocol utilizes a general-purpose state-of-the-art 3D image analysis software platform which facilitates image visualization, segmentation/labelling, and measurements ranging from simple to complex.
The most time-consuming task in the protocol is semi-automated s...

Micro-computed tomography (&#181;CT) imaging has been widely used in preclinical bone research, providing noninvasive, high-resolution images to evaluate the microstructure of bones1,2,3,4,5. &#181;CT involves a large number of X-ray images, obtained from a rotating sample or by using a rotating X-ray source and detector. Algorithms are used to reconstruct 3D volumetric data in the form of a stack of image slices. Clinical CT is the gold standard for 3D imaging of human bones, and &#181;CT is a commonly used technique for evaluating bone healing efficiency in experimental animals1,2,3,4,6,7. Mineralized bone has excellent contrast to X-ray, while soft tissues have relatively poor contrast unless a contrast agent is used. In the assessment of fracture healing, &#181;CT generates images that provide detailed information about the 3D structure and density of the mineralized callus. In vivo &#181;CT scanning can also be used for longitudinal, time-course assessment of fracture healing.
The quantification of intact cortical and trabecular bone using &#181;CT is generally well-established and standardized8. Although preclinical studies use a variety of quantification methodologies to analyze fracture healing9,10,11, a detailed protocol of &#181;CT image analysis for callus quantification has not been published yet.Therefore, the aim of this study is to provide a detailed step-by-step protocol for &#181;CT imaging and analysis of bone healing callus.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>10% neutral buffered formalin&#160;</td>
			<td>Fisher chemical</td>
			<td>SF100-20</td>
			<td>Used for bone tissue fixation</td>
		</tr>
		<tr>
			<td>Avizo</td>
			<td>Thermo Scientific</td>
			<td></td>
			<td>Image processing and analysis software</td>
		</tr>
		<tr>
			<td>Hydroxyapatite phantom&#160;</td>
			<td>Micro-CT HA D4.5, QRM</td>
			<td>QRM-70128</td>
			<td></td>
		</tr>
		<tr>
			<td>Image Processing Language</td>
			<td>Scanco</td>
			<td></td>
			<td>Used to convert raw images to DICOM images</td>
		</tr>
		<tr>
			<td>Micro-Mosquito Straight Hemostatic Forceps</td>
			<td>Medline</td>
			<td></td>
			<td>Used to remove the intramedullary pin&#160;</td>
		</tr>
		<tr>
			<td>Microsoft Excel</td>
			<td>Microsoft</td>
			<td></td>
			<td>Spreadsheet software</td>
		</tr>
		<tr>
			<td>Scanco mCT system (vivaCT 40)</td>
			<td>Scanco</td>
			<td></td>
			<td>Used for &#181;CT imaging&#160;</td>
		</tr>
	</tbody>
</table>

assessment of bone fracture healing using micro-computed tomography

Micro-computed tomography (&#181;CT) is the most common imaging modality to characterize the three-dimensional (3D) morphology of bone and newly formed bone during fracture healing in translational science investigations. Studies of long bone fracture healing in rodents typically involve secondary healing and the formation of a mineralized callus. The shape of the callus formed and the density of the newly formed bone may vary substantially between timepoints and treatments. Whereas standard methodologies for quantifying parameters of intact cortical and trabecular bone are widely used and embedded in commercially available software, there is a lack of consensus on procedures for analyzing the healing callus. The purpose of this work is to describe a standardized protocol that quantitates bone volume fraction and callus mineral density in the healing callus. The protocol describes different parameters that should be considered during imaging and analysis, including sample alignment during imaging, the size of the volume of interest, and the number of slices that are contoured to define the callus.

To monitor bone formation during fracture healing, a mid-diaphyseal open tibial fracture was induced in adult, male C75BL/6J mice. The fracture was stabilized using an intramedullary nail, an established model of secondary healing13. Callus tissues were harvested at days 14, 21, and 28 post-fracture12. These timepoints represent different phases of healing. Endochondral bone formation during secondary bone healing proceeds via initial formation of a fibro-cartilagi...

Watch this Scientific Journal Video about Assessment of Bone Fracture Healing Using Micro-Computed Tomography at JoVE.com

Assessment of Bone Fracture Healing Using Micro-Computed Tomography

Micro-computed tomography (&#181;CT) is a non-destructive imaging tool that is instrumental in assessing bone structure in preclinical studies, however there is a lack of consensus on &#181;CT procedures for analyzing the bone healing callus. This study provides a step-by-step &#181;CT protocol that allows the monitoring of fracture healing.

Micro-computed tomography (&#181;CT) is the most common imaging modality to characterize the three-dimensional (3D) morphology of bone and newly formed ...

Micro-CT is a very common approach for quantifying 3D morphology and quality of bone. Although analysis protocols are fairly established for characterizing intact cortical and trabecular bone, there is a less consensus on the protocol for analyzing fracture healing. This technique involves noninvasive imaging and accurate, calibrated 3D analysis using a good balance of manual and automated techniques.It also uses a sophisticated and flexible software environment. Demonstrating the procedure will be Hwabok Wee, a research associate from my laboratory. To begin, take a custom-developed 3D printed scanning fixture or similar that includes a miniature hydroxyapatite phantom for bone mineral density calibration.Place up to six long bone samples into the fixture for the simultaneous scanning of multiple samples. Place the prepared fixture in a syringe or a conical tube similar to the scanning field of view's diameter. Fill the syringe with a preservative, like saline, to prevent samples from drying out during the scanning process.After confirming the calibration of the micro-CT machine, align the sample fixture's center line with the approximate center line of the micro-CT to ensure that the samples are within the field of view and their long axes have orientation approximately coinciding with the axial direction of the resulting images. Next, set the scanning parameters of the micro-CT system by setting the energy or intensity to 55 kilovoltage peak, current to 145 microampere, isotropic voxel size to 10.5 micrometers, and integration time to 300 milliseconds. Then visually inspect the scout images in different views to cover the whole volume of all callus samples.Start the scan acquisition, and, once complete, convert the images to a DICOM stack to import them into the analysis software. To start with image cropping, pick one sample at a time, and crop each image stack, ensuring the whole sample is included in the cropped volume. Save the cropped image by clicking the File tab on the top left side of the screen, selecting Save Project As, and then selecting Minimize project size.To denoise the image, click the File tab and choose the image to be processed using Open Data, which opens the image in the Project View window in the top left corner of the screen. Right click to select Image Processing, followed by Filter Sandbox, and then click Create. In the Properties window on the left bottom corner of the screen, choose Data as the preview type.Select the filter type from the dropdown menu next to Filter and choose 3D for interpretation. Keeping Separable as the kernel type in the dropdown menu, fill in the values of standard deviation and kernel size factor in the available empty box. Then select Same as input from the dropdown menu next to the output.And finally, click Apply. For misaligned samples, the user may perform image realignment by creating a 3D-rendered image of the sample by selecting the filtered, cropped image from the Project View window. Right click to select Display and then Volume Rendering from the dropdown menu.Then click Create to visually check the 3D-rendered image in the sagittal and frontal planes. Then manually rotate the rendered volume to obtain a good alignment in the longitudinal axis. To apply the transformation in the rotated images, in the Properties window, click the Transform Editor.Then go to Transform Editor Manipulator and select Transformer from the dropdown menu. If needed, rotate, realign, and then click the Transform Editor again to lock the image. Next, to create new transverse plane image slices, resample the filtered image by selecting the image from the Project View window.Right click to select Geometry Transform, followed by Resample Transformed Image from the dropdown menu, and then click Create. In the Properties window, go to Data, and from the dropdown menu, select Standard for interpolation, choose Extended for mode and Voxel Size for preserve. Enter zero in the available blank box for padding value, and finally, click Apply.To define the volume of interest, go through the transverse image slices, identify the fracture callus's center plane, and define it based on the proximal and distal lens of the callus. If the callus ends are difficult to specify, define the volume based on a standardized distance away from the callus center plane. To segment the outer boundary of the callus following the reassembly of transformed images, click the Segmentation tab in the second tab row from the top of the screen.In the segmentation editor window, select transformed image from the dropdown menu next to the image. In the MATERIALS window, double click Add. By doing so, two tabs named Material3 and Material4 will appear.Right click to rename Material3 to callus and Material4 to cortical bone. Next, in the SELECTION window, click on the lasso icon. From the appearing options, select Freehand for the 2D mode, Inside for the 3D mode, and both Auto trace and Trace edges for options.Then use the lasso to mark the outer boundary of callus. Repeat the contouring steps with slices sampled across the volume of interest, and the slices can be spaced apart, for example, by 20 slices. To create a complete callus label, in the MATERIALS window, choose the callus file, click the Selection tab on the top of the screen, and select Interpolate from the dropdown menu.Then, in the Selection window, click on the plus sign. Next, segment the cortical bone, including the medullary cavity. Then interpolate the contoured periosteal cortex surface to create a cortical bone label as performed previously for the callus.To calculate the callus's contoured volume and mean gray value, click the Segmentation tab on the top row of the screen and select Material Statistics from the dropdown menu to generate a table of calculated values. Note that the values of the cortical bone and the callus are provided separately after subtracting the cortical bone. Export the generated table and save the data by clicking Export into Workspace.To convert the grayscale units to bone mineral density, crop the 3D image of the 4.5-millimeter HA phantom from the whole image and click Segmentation. To draw circles at the first and the last slices, in the MATERIALS window, click Add four times. Then right click to rename Material3, 4, 5, and 6 to Phantom1, 2, 3, and 4 respectively.Next, select Phantom1. Click the brush icon in the Selection window and use the slider to adjust the brush size such that the size of the circle is smaller than that of the phantom. To create a volume for each HA cylinder, apply interpolation by selecting Phantom1 in the MATERIALS window, clicking the Selection tab on the top row of the screen, and selecting Interpolate from the dropdown menu.Then, in the SELECTION window, click the plus sign. Repeat this process with the remaining HA cylinders. Use the generated 3D labels to calculate the mean gray values of the four analyzed HA cylinders.Plot the mean gray values and the corresponding bone mineral density, or BMD, values provided by the phantom manufacturer. Generate a correlation equation between BMD and the gray values using linear regression. To segment the mineralized callus, click Add in the MATERIALS window.Then right click to rename the new material to callus mineralized. Next, select Callus in the MATERIALS window, followed by clicking Select. Then click Threshold in the SELECTION window.Select the lower value and apply the calculated threshold from the HA phantom in threshold masking. Then click Select only current material in the SELECTION window, followed by clicking Select Masked Voxels. Then select callus mineralized in the MATERIALS window and click the plus sign in the SELECTION window.Finally, click 3D of callus mineralized in the MATERIALS window. The micro-CT images analyzed at three time points showed the substantial formation of mineralized callus on day 14. Incremental increases in bone fraction volume and bone mineral density were seen as healing proceeded from day 14 to days 21 and 28, consistent with bony bridging of the fracture gap.As expected, the callus underwent resorption or remodeling between days 21 and 28, as evidenced by a decline in total callus volume. Cortical bridging of the callus was more evident at day 28 than at any preceding time point. For complex fractures, we recommend carefully reviewing the resulting semi-automated segmentation by scrolling through all image slices, sometimes in different planes, and adjusting contours if needed.Once the fracture callus is accurately segmented, outcome parameters, in addition to the ones reported in this protocol, can be computed with additional scripts. These include, for example, moments of inertia and connectivity density.

Research

JoVE Journal

Biology

Non-invasive 3D-Visualization with Sub-micron Resolution Using Synchrotron-X-ray-tomography

Little is known about the internal organization of many micro-arthropods with body sizes below 1 mm. The reasons for that are the small size and the hard ...

Psychophysiological Stress Assessment Using Biofeedback 

In the last half century, research in biofeedback has shown the extent to which the human mind can influence the functioning of the autonomic nervous ...

Production of Transgenic Xenopus laevis by Restriction Enzyme Mediated Integration and Nuclear Transplantation

Production of Transgenic Xenopus laevis by Restriction Enzyme Mediated Integration and Nuclear Transplantation

Stable integration of cloned gene products into the Xenopus genome is necessary to control the time and place of expression, to express genes at later ...

Long-term Culture of Human Breast Cancer Specimens and Their Analysis Using Optical Projection Tomography

Breast cancer is a leading cause of mortality in the Western world. It is well established that the spread of breast cancer, first locally and later ...

Fundamental Technical Elements of Freeze-fracture/Freeze-etch in Biological Electron Microscopy

Freeze-fracture/freeze-etch describes a process whereby specimens, typically biological or nanomaterial in nature, are frozen, fractured, and replicated ...

A Protocol for Using Gene Set Enrichment Analysis to Identify the Appropriate Animal Model for Translational Research

Recent studies that compared transcriptomic datasets of human diseases with datasets from mouse models using traditional gene-to-gene comparison ...

Fish Sperm Assessment Using Software and Cooling Devices

For gamete quality evaluation, there are innovative, rapid, and quantitative techniques that can provide useful data for aquaculture. Computerized systems ...

Assessment of Global Ocular Structure Following Spaceflight Using a Micro-Computed Tomography (Micro-CT) Imaging Method

Assessment of Global Ocular Structure Following Spaceflight Using a Micro-Computed Tomography Micro-CT Imaging Method

Reports show that prolonged exposure to a spaceflight environment produces morphologic and functional ophthalmic changes in astronauts during and after an ...

Array Tomography Workflow for the Targeted Acquisition of Volume Information using Scanning Electron Microscopy

Electron microscopy is applied in biology and medicine for imaging of cellular and structural details at nanometer resolution. Historically, Transmission ...

Transverse Fracture of the Mouse Femur with Stabilizing Pin

Fracture repair is an essential function of the skeleton that cannot be reliably modeled in vitro. A mouse injury model is an efficient approach to test ...