The results about the microvascular response to particulate air pollution are reproduced with permission from Environmental Health Perspectives24. The validated meteorological and air quality data were kindly provided by The Belgian Royal Meteorological Institute and the Flemish Environmental Agency. The retinal image analysis software was obtained from Dr. N. Ferrier (Madison School of Engineering and the Fundus Photograph Reading Center, Department of Ophthalmology and Visual Sciences, University of Wisconsin&#8211;Madison). Tijs Louwies and Eline Provost are supported with a VITO fellowship. Eline Provost holds an aspirant research fellowship of the Flemish Scientific Fund. Tim S. Nawrot is holder of a European Research Council starting grant.

The Ethics Board of Hasselt University and University Hospital Antwerp approved the studies. Participants gave their written informed consent to participate.
1. Instrument Setup
<ol>
	<li>Remove the black protection shells from the digital retinal camera and the main block of the unit.</li>
	<li>Open the battery compartment and place the battery in the camera. Do not disconnect the wire connecting the battery and the main unit.</li>
	<li>Screw the camera onto the main unit and connect the two wires. Connect the main unit to the power grid and to the computer with the supplied USB cables.</li>
	<li>Start the main unit by switching the on/off button to &#8220;on&#8221;. Start the camera by switching the on/off button to &#8220;on&#8221;.</li>
	<li>Start the computer. This will prevent connection errors between the main unit and the computer.</li>
</ol>
2. Capturing Photograph
<ol>
	<li>Start the Retinal Imaging Control Software (and fill in the required password). The software is a part of the digital retinal camera (see materials table for link).</li>
	<li>Start the study by clicking the &#8220;Study&#8221; icon in the upper left part of the screen. For a new patient, fill in all the details such as patient ID, patient name, date of birth, etc. If the patient is already in the system, fill in the &#8220;patient ID&#8221; and use the &#8220;Search history list&#8221;. Double-click on the name of the patient to start the study.</li>
	<li>Ask the patient to take a seat before the camera, place his/her chin on the chin rest and the forehead against the forehead rest and &#8220;lock&#8221; the head to take a photograph.</li>
	<li>Ask the patient to look straight into the lens of the camera. Move the camera in the horizontal (X-Y) plane to the right or left eye.</li>
	<li>Use the chin rest to position the cornea of the patient inside the two circles that appear on the camera display. Fine-tune by using the wheel on the joystick.</li>
	<li>Move the camera forward, backward, and sideways in the X-Y plane in order to position the pupil of the patient within the circles. Make sure the pupil forms a continuous circle. By doing so, the iris of the patient will be split up in two pieces.</li>
	<li>Use the &#8220;back trigger&#8221; on the joystick to switch from the cornea to the retina. At this stage, the patient should observe a green light. Ask the patient to look at the green light.</li>
	<li>Focus the camera by aligning the two lines that pop up when the wheel at the base of the joystick is turned. Turn the wheel until the two lines form a continuous line.</li>
	<li>Use the green light to place the eye in the optimal position for a photograph. If required, move the light using the arrow buttons at the right side of the camera. Position the green light in a way that the optic disc is centered on the camera display.</li>
	<li>Search for 2 white spots which appeared after switching to the retina (in step 2.7). To find the spots, move the unit in the X-Y plane. The spots are visible as a blurry stain. Move the unit forward or backwards until blurry stains turn into bright, white spots. The brighter and rounder the spots, the better the quality of the picture is. Position the spots until both are visible. Use the little wheel on the joystick to bring the spots to the middle of the camera display.</li>
	<li>Confirm that the two lines (from step 2.8) form a continuous line. The optic disc is centered on the camera display and is flanked by two bright, white spots. Take the retinal photograph by firing the button on top of the joystick.</li>
	<li>Save the photograph by pressing the &#8220;Study Complete&#8221; button on the lower right corner of the computer screen. Completing the study will automatically save the pictures in a map and close the study.</li>
</ol>
3. Analysis of Retinal Photograph
<ol>
	<li>Determine the scale ratio by measuring the distance between the center&#160;of macula (fovea) and the center&#160;of the optic disc (blind spot). Anatomically this distance is determined to be 4,500 &#181;m or 2.5x&#160;the diameter of the optic disc, with the latter being approximately 1,800 &#181;m. Ensure the distance is measured in pixels. Calculate the scale ratio by dividing 4,500 by the distance (in pixels) between the macula and blind spot.</li>
	<li>Open the retinal vessel analysis software &#8220;IVAN&#8221;. 
	NOTE: The software is created at the University of Wisconsin at Madison. Detailed information on the usage of IVAN is taken from the manual.</li>
	<li>Fill in the scale ratio and proceed through the configuration.</li>
	<li>Verify that three yellow rings appear on the retinal photograph. The scale ratio determines the radius of the inner circle and encloses the optic disc. Verify that the middle point of the inner ring is on the middle point of the optic disc. If this is not the case, adjust the location of the circle by using the cursor keys. The radii of the middle and outer circles are 2x&#160;and 3x&#160;larger than the radius of the inner circle, respectively. In this way, zones A and B are created at a fixed distance from the optic disc.</li>
	<li>Check that the retinal image has the optic disc in the center of the photograph. This ensures a sharp focus of the image in zone B and this will facilitate the grading process (Figure 4A).</li>
	<li>Observe that the software automatically detects the blood vessels and assigns these vessels as venules (Figure 4B).</li>
	<li>Distinguish the vessels between arterioles and venules based on physiological differences. Arterioles will be indicated in red and venules in blue (Figure 4C). Use the following guidelines to identify each vessel:
	<ol>
		<li>Determine the vessel color. Arterioles have a lighter orange-red color with a strong central light reflection. Veins have darker purple-red color with little or no central light reflex.</li>
		<li>Determine the course of the vessel. Arterioles tend to be straighter and smoother in outline; they are more regular in both path and outline. Venules are generally more tortuous, and more irregular in outline and diameter. Venules are broader in diameter at the disc margin than the corresponding arterioles.</li>
		<li>Identify the vessel by looking at the annotation of the preceding vessel. In principle, arterioles alternate with venules. Therefore, if a distinct venule is measured, the next vessel is more likely to be an arteriole.</li>
		<li>Define the crossing pattern. As a general rule, arterioles do not cross arterioles and venules do not cross venules. If a vessel of unknown identity crosses a venous branch within or distal to Zone B, then the unknown vessel is an arteriole. If it crosses an arteriolar branch within or distal to Zone B, then it is a venule.</li>
		<li>Identify smaller branches by tracing them proximally to their branching from a parent vessel, the identity of which may be evident from the first two guidelines. Use angles between vessels to differentiate crossings and branchings. 
		NOTE: Crossings are frequently almost perpendicular (90&#176;) or, if the two vessels are coursing in parallel, the angle of the crossing may be very shallow (less than 30&#176;). Branchings are usually somewhat less than perpendicular (with the angle between the two branches from 30&#176; to 45&#176;).</li>
		<li>Select the full length of the vessel in the grading zone. Make sure that the standard deviation of the selected vessel does not exceed the value of 10. Smaller standard deviations indicate a good measurement.</li>
	</ol>
	</li>
	<li>Use the software tools to select vessels that were not selected by the software itself. The same rules apply for these vessels as for the vessels automatically selected by the software.</li>
	<li>Determine Central Retinal Arteriolar and Venular Equivalent (CRAE and CRVE) automatically in IVAN.</li>
	<li>Calculate the CRAE and CRVE from their respective branching daughter vessels using revised formulas of Parr and Hubbard28. 
	NOTE: The relationship between trunks and branches, with empirically derived branching coefficients, is given in following two formulas to approximate vessel equivalents. IVAN uses the six largest arterioles and venules for calculating CRAE and CRVE. The formulas are applied in an iterative procedure to pair up the six largest arterioles (or venules) until the central arteriolar (or venular) vessel equivalent is obtained. 
	Arterioles: <img alt="Equation 1" fo:content-width="1in" src="/files/ftp_upload/51904/51904eq1.jpg" /> (1) 
	Venules: <img alt="Equation 2" fo:content-width="1in" src="/files/ftp_upload/51904/51904eq2.jpg" /> (2) 
	where w1, w2, and W are the widths of the narrower branch, the wider branch, and the parent trunk, respectively. 
	NOTE: Assume that in a retinal photograph the six largest arterioles are 120, 110, 100, 90, 80, and 70 &#181;m wide. Put 120 and 70 into equation (1), as well as 110 and 80, and 100 and 90. After the first iteration there are three values: 122.2, 120.0, and 118.4. Perform the next iteration by pairing 122.2 and 118.4, yielding 149.8. Carry over the middle number (120.0) to the final iteration. Pair 149.8 and 120.0 to yield 168.7 for CRAE.</li>
</ol>

The authors declare they have no actual or potential competing financial interests.

Retina image analysis is proposed as a convenient tool for studying microvascular responses in epidemiological studies. When the operator is experienced, it takes less than 5&#160;min&#160;to take a fundus picture. Furthermore, this unobtrusive procedure for visualizing the microcirculation can be used for participants from early age up to old age.
Literature is increasing with respect to the associations between morphological changes in the retinal vasculature (for example change in vessel ca...

The microcirculation consists of blood vessels with diameters less than 150 &#181;m and includes smallest resistance arteries, arterioles, capillaries, and venules. These vessels make up a large part of the circulatory system and play an important role in maintaining cardiovascular health. The vessel diameter of 150 &#181;m is a physiological and a physical limit. The rheological properties of vessels with a diameter less than 150 &#181;m differ from large arteries. Furthermore, most of the autoregulatory resistance changes occur downstream from 150 &#181;m in vascular beds exhibiting blood flow autoregulation1. The microcirculation has two important functions. The primary function is to provide cells with oxygen and metabolic substrates in order to match tissue demand and to drain waste products and carbon dioxide. Alterations in the number of exchange vessels and the microvascular flow patterns reduces the effective exchange surface area and may lead to suboptimal tissue perfusion and a failure to meet metabolic demand2. Further, the hydrostatic pressure drops within the vascular bed and the microcirculation plays a role in regulating the overall peripheral resistance3.
The retina is a layered tissue lining the interior of the eye. Its main function is to convert the incoming light into a neural signal that is further propagated to the visual cortex for processing visual information. The function of the retina is to see the outside world and all the ocular structures involved in this process are optically transparent. This makes the retinal tissue accessible for non-invasive imaging of the microvasculature4. Retinal imaging is being used to identify diseases of the eye. For example, an advanced form of macular degeneration can lead to vision loss because of abnormal blood vessel growth into the macula. These blood vessels tend to be more permeable and subject to bleeding and leaking of blood and proteins within or below the retina. The latter events are responsible for the irreversible damage to the photoreceptors. Development of glaucoma correlates with a damaging of ganglion cells and their axons. The effect of this process leads to cupping of the optic disc, which can be observed in retinal images5. Diabetic retinopathy is caused by hyperglycemia that leads to damage in&#160;the retinal vessel walls. This can result in ischemia, the growth of new blood vessels and a change in the vascular geometric network. Furthermore, the blood-retinal barrier may be subject to breakdown, causing leakage of dilated hyperpermeable capillaries and aneurysms6.
Retinal microvasculature shows homology with the microvascular beds found in the heart, lungs, and brain7. It is established that systemic diseases that affect the microcirculation of the brain can cause parallel changes in the retina. Arteriolar narrowing and enhanced arteriolar light reflex of the retina is associated with vessel abnormalities, white matter lesions and lacunes that are caused by cerebral small vessel disease8. A significant relationship was discovered between narrower retinal venules, an altered retinal microvascular network and the occurrence of Alzheimer disease. It is suggested that brains of patients have an altered cerebral microvasculature that is also observable in the retina9.
Evidence is also increasing about the correlation between retinal vascular changes and coronary heart disease10,11. The ratio between the diameter of retinal arteries and retinal veins (A/V) has been shown to be a sensitive proxy to reflect hypertension and atherosclerosis12. A narrowing of the arteries and widening of the veins, leading to a decreased A/V ratio, corroborates risk of stroke and myocardial infarction13. Hypertension can cause direct retinal ischemia and retinal infarcts that become visible as cotton wool spots and deep retinal white spots14. Serre and Sasongko recently summarized the literature and they concluded that exposure to lifestyle and environmental risk factors (e.g., diet, physical activity, smoking, and air pollution) can induce morphological changes in the retinal microvascular bed15. Importantly, such retinal changes have been associated with cardiovascular risk factors, even before clinical manifestations of diseases16.
Significant increases in the incidence of cardiovascular morbidity and mortality have been attributed to long- and short-term exposures to particulate matter air pollution17,18. Research indicates that particulate matter (PM), an important fraction of air pollution, contributes to the development of cardiovascular disease and induces cardiovascular events19,20. An impairment of the function of the microvascular bed is thought to play a role in the observed associations. In this respect, an association between exposure to air pollution and arteriolar narrowing in the retina has been reported by Adar and colleagues21. The retinal arteriolar caliber was narrower and venular caliber was wider among the 4607 participants of the Multi-Ethnic Study of Atherosclerosis (MESA) that were living in areas with increased long- and short-term exposure to PM2.5 (particulate matter &#8804; 2.5 &#956;m in diameter)21. Systemic inflammation caused by chronic air pollution exposure may result in wider venular diameters22. This corroborates&#160;the studies that report the impact of smoking on the retinal microvascular bed23. A recent publication reports on the association between short-term air pollution exposure and microvascular changes in healthy adults (22-63 years of age) measured with retinal fundus photography24. An increase in PM10 (particulate matter &#8804; 10 &#956;m in diameter) and BC (black carbon, a combustion by-product that can be used as a proxy for traffic-related diesel exhaust) was associated with a decrease in arteriolar caliber24,25.
In this scientific video protocol, the procedures are described to collect fundus pictures of the eye, to perform image analysis to obtain arteriolar and venular vessel calibers, and to calculate Central Retinal Arteriolar Equivalent (CRAE) and Central Retinal Venular Equivalent (CRVE). Retinal imaging is gaining increased attention because the retina is the only tissue that allows an unobtrusive analysis of the microvasculature and images can be collected from early age up to old age26,27. CRAE and CRVE appear to be sensitive parameters that reflect the impact of modifiable lifestyle and environmental cardiovascular disease risk factors on the microvasculature. In the manuscript, the repeatability of the vessel analysis is demonstrated. Furthermore, the applicability of retinal microvasculature analysis in epidemiological studies is shown by summarizing our findings obtained in a repeated-measures design with a focus on the impact of particulate air pollution exposure24.

<table border="0" cellpadding="0" cellspacing="0" width="970">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:321px;">Name of Material/ Equipment</td>
			<td style="width:223px;">Company</td>
			<td style="width:196px;">Catalog Number</td>
			<td style="width:231px;">Comments/Description</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Canon CR-2 nonmydriatic retinal camera&#160;</td>
			<td>Hospithera (Brussels, Belgium)</td>
			<td></td>
			<td>http://www.usa.canon.com/cusa/healthcare/products/eyecare/digital_non_mydriatic_retinal_cameras/cr_2. Any other retinal camera with comparable resolution and specifications can be used for the analysis of the retinal microvasculature. Compatibility should&#160; be checked before starting a study.</td>
		</tr>
		<tr height="357">
			<td height="357" style="height:357px;width:321px;">IVAN: Vessel Measurement Software</td>
			<td style="width:223px;"></td>
			<td style="width:196px;"></td>
			<td style="width:231px;">This software can be used without charge for scientific purpose. It can be obtained by contacting Dr. Nicola Ferrier (Madison School of Engineering and the Fundus Photograph Reading 
			Center, Department of Ophthalmology and Visual Sciences, University of Wisconsin&#8211;Madison). http://directory.engr.wisc.edu/me/faculty/ferrier_nicola. Phone: (608) 265-8793, 
			Fax: (608) 265-2316 or e-mail: ferrier@engr.wisc.edu 
			&#160;</td>
		</tr>
	</tbody>
</table>

fundus photography as a convenient tool to study microvascular responses to cardiovascular disease risk factors in epidemiological studies

The microcirculation consists of blood vessels with diameters less than 150 &#181;m. It makes up a large part of the circulatory system and plays an important role in maintaining cardiovascular health. The retina is a tissue that lines the interior of the eye and it is the only tissue that allows for a non-invasive analysis of the microvasculature. Nowadays, high-quality fundus images can be acquired using digital cameras. Retinal images can be collected in 5 min or less, even without dilatation of the pupils. This unobtrusive and fast procedure for visualizing the microcirculation is attractive to apply in epidemiological studies and to monitor cardiovascular health from early age up to old age.
Systemic diseases that affect the circulation can result in progressive morphological changes in the retinal vasculature. For example, changes in the vessel calibers of retinal arteries and veins have been associated with hypertension, atherosclerosis, and increased risk of stroke and myocardial infarction. The vessel widths are derived using image analysis software and the width of the six largest arteries and veins are summarized in the Central Retinal Arteriolar Equivalent (CRAE) and the Central Retinal Venular Equivalent (CRVE). The latter features have been shown useful to study the impact of modifiable lifestyle and environmental cardiovascular disease risk factors.
The procedures to acquire fundus images and the analysis steps to obtain CRAE and CRVE are described. Coefficients of variation of repeated measures of CRAE and CRVE are less than 2% and within-rater reliability is very high. Using a panel study, the rapid response of the retinal vessel calibers to short-term changes in particulate air pollution, a known risk factor for cardiovascular mortality and morbidity, is reported. In conclusion, retinal imaging is proposed as a convenient and instrumental tool for epidemiological studies to study microvascular responses to cardiovascular disease risk factors.

Repeatability of CRAE and CRVE Determination
A panel of 61 individuals between 22 to 56 years old and free of clinically diagnosed cardiovascular diseases was recruited for studying technical repeatability and within-rater variability of Central Retinal Arteriolar Equivalent (CRAE) and Central Retinal Venular Equivalent (CRVE) determinations. The fundus of the right eye of each individual was photographed twice within a time period of 5&#160;min&#160;using a retinal camera (Figures 1</str...

Watch this Scientific Journal Video about Fundus Photography as a Convenient Tool to Study Microvascular Responses to Cardiovascular Disease Risk Factors in Epidemiological Studies at JoVE.com

Fundus Photography as a Convenient Tool to Study Microvascular Responses to Cardiovascular Disease Risk Factors in Epidemiological Studies

Retinal image analysis is an unobtrusive procedure for visualizing the microcirculation. The impact of cardiovascular disease risk factors can result in changes of retinal vessel calibers. The procedures to acquire fundus images and the steps for calculating the vessel calibers are described.

The microcirculation consists of blood vessels with diameters less than 150 &#181;m. It makes up a large part of the circulatory system and plays an ...

fundus-photography-as-convenient-tool-to-study-microvascular

Research

JoVE Journal

Medicine

19.0K Views.  Flemish Institute for Technological Research (VITO). Retinal image analysis is an unobtrusive procedure for visualizing the microcirculation. The impact of cardiovascular disease risk factors can result in changes of retinal vessel calibers. The procedures to acquire fundus images and the steps for calculating the vessel calibers are described.

Video: Fundus Photography as a Convenient Tool to Study Microvascular Responses to Cardiovascular Disease Risk Factors in Epidemiological Studies

Spectral Karyotyping to Study Chromosome Abnormalities in Humans and Mice with Polycystic Kidney Disease

Conventional method to identify and classify individual chromosomes depends on the unique banding pattern of each chromosome in a specific species being analyzed 1, 2. This classical banding technique, however, is not reliable in identifying complex chromosomal aberrations such as those associated with cancer. To overcome the limitations of the banding technique, Spectral Karyotyping (SKY) is introduced to provide much reliable information on chromosome abnormalities.
SKY is a multicolor fluorescence in-situ hybridization (FISH) technique to detect metaphase chromosomes with spectral microscope 3, 4. SKY has been proven to be a valuable tool for the cytogenetic analysis of a broad range of chromosome abnormalities associated with a large number of genetic diseases and malignancies 5, 6. SKY involves the use of multicolor fluorescently-labelled DNA probes prepared from the degenerate oligonucleotide primers by PCR. Thus, every chromosome has a unique spectral color after in-situ hybridization with probes, which are differentially labelled with a mixture of fluorescent dyes (Rhodamine, Texas Red, Cy5, FITC and Cy5.5). The probes used for SKY consist of up to 55 chromosome specific probes 7-10.
The procedure for SKY involves several steps (Figure 1). SKY requires the availability of cells with high mitotic index from normal or diseased tissue or blood. The chromosomes of a single cell from either a freshly isolated primary cell or a cell line are spread on a glass slide. This chromosome spread is labeled with a different combination of fluorescent dyes specific for each chromosome. For probe detection and image acquisition,the spectral imaging system consists of sagnac interferometer and a CCD camera. This allows measurement of the visible light spectrum emitted from the sample and to acquire a spectral image from individual chromosomes. HiSKY, the software used to analyze the results of the captured images, provides an easy identification of chromosome anomalies. The end result is a metaphase and a karyotype classification image, in which each pair of chromosomes has a distinct color (Figure 2). This allows easy identification of chromosome identities and translocations. For more details, please visit Applied Spectral Imaging website (<a href="http://www.spectral-imaging.com/" target="_blank">http://www.spectral-imaging.com/</a>).
SKY was recently used for an identification of chromosome segregation defects and chromosome abnormalities in humans and mice with Autosomal Dominant Polycystic Kidney Disease (ADPKD), a genetic disease characterized by dysfunction in primary cilia 11-13. Using this technique, we demonstrated the presence of abnormal chromosome segregation and chromosomal defects in ADPKD patients and mouse models 14. Further analyses using SKY not only allowed us to identify chromosomal number and identity, but also to accurately detect very complex chromosomal aberrations such as chromosome deletions and translocations (Figure 2).

Spectral Karyotyping (SKY) is an advanced cytogenetics technique to identify genomic and chromosomal aberrations. This technique takes advantage of chromosome painting probes, which allow classification of all chromosomes. SKY can also identify complex chromosome aberrations and segregation defects in mice and humans with various diseases, including polycystic kidney disease.

Conventional method to identify and classify individual chromosomes depends on the unique banding pattern of each chromosome in a specific species being ...

Isolation and Excision of Murine Aorta; A Versatile Technique in the Study of Cardiovascular Disease

Cardiovascular disease is a broad term describing disease of the heart and/or blood vessels. The main blood vessel supplying the body with oxygenated blood is the aorta. The aorta may become affected in diseases such as atherosclerosis and aneurysm. Researchers investigating these diseases would benefit from direct observation of the aorta to characterize disease progression as well as to evaluate efficacy of potential therapeutics. The goal of this protocol is to describe proper isolation and excision of the aorta to aid investigators researching cardiovascular disease. Isolation and excision of the aorta allows investigators to look at gross morphometric changes as wells as allowing them to preserve and stain the tissue to look at histologic changes if desired. The aorta may be used for molecular studies to evaluate protein and gene expression to discover targets of interest and mechanisms of action. This technique is superior to imaging modalities as they have inherent limitations in technology and cost. Additionally, primary isolated cells from a freshly isolated and excised aorta can allowing researchers to perform further in situ and in vitro assays. The isolation and excision of the aorta has the limitation of having to sacrifice the animal however, in this case the benefits outweigh the harm as it is the most versatile technique in the study of aortic disease.

Pathology of the aorta can lead to severe morbidity and mortality, therefore research of disease progression and potential therapies is warranted. Here, we present a protocol to isolate and excise the murine aorta to aid researchers in their investigation of cardiovascular disease.

Cardiovascular disease is a broad term describing disease of the heart and/or blood vessels. The main blood vessel supplying the body with oxygenated ...

Adapting Human Videofluoroscopic Swallow Study Methods to Detect and Characterize Dysphagia in Murine Disease Models

This study adapted human videofluoroscopic swallowing study (VFSS) methods for use with murine disease models for the purpose of facilitating translational dysphagia research. Successful outcomes are dependent upon three critical components: test chambers that permit self-feeding while standing unrestrained in a confined space, recipes that mask the aversive taste/odor of commercially-available oral contrast agents, and a step-by-step test protocol that permits quantification of swallow physiology. Elimination of one or more of these components will have a detrimental impact on the study results. Moreover, the energy level capability of the fluoroscopy system will determine which swallow parameters can be investigated. Most research centers have high energy fluoroscopes designed for use with people and larger animals, which results in exceptionally poor image quality when testing mice and other small rodents. Despite this limitation, we have identified seven VFSS parameters that are consistently quantifiable in mice when using a high energy fluoroscope in combination with the new murine VFSS protocol. We recently obtained a low energy fluoroscopy system with exceptionally high imaging resolution and magnification capabilities that was designed for use with mice and other small rodents. Preliminary work using this new system, in combination with the new murine VFSS protocol, has identified 13 swallow parameters that are consistently quantifiable in mice, which is nearly double the number obtained using conventional (i.e., high energy) fluoroscopes. Identification of additional swallow parameters is expected as we optimize the capabilities of this new system. Results thus far demonstrate the utility of using a low energy fluoroscopy system to detect and quantify subtle changes in swallow physiology that may otherwise be overlooked when using high energy fluoroscopes to investigate murine disease models.

This study successfully adapted human videofluoroscopic swallowing study (VFSS) methods for use with murine disease models for the purpose of facilitating translational dysphagia research.

This study adapted human videofluoroscopic swallowing study (VFSS) methods for use with murine disease models for the purpose of facilitating ...

Using Adeno-associated Virus as a Tool to Study Retinal Barriers in Disease

M&#252;ller cells are the principal glial cells of the retina. Their end-feet form the limits of the retina at the outer and inner limiting membranes (ILM), and in conjunction with astrocytes, pericytes and endothelial cells they establish the blood-retinal barrier (BRB). BRB limits material transport between the bloodstream and the retina while the ILM acts as a basement membrane that defines histologically the border between the retina and the vitreous cavity. Labeling M&#252;ller cells is particularly relevant to study the physical state of the retinal barriers, as these cells are an integral part of the BRB and ILM. Both BRB and ILM are frequently altered in retinal disease and are responsible for disease symptoms.
There are several well-established methods to study the integrity of the BRB, such as the Evans blue assay or fluorescein angiography. However these methods do not provide information on the extent of BRB permeability to larger molecules, in nanometer range. Furthermore, they do not provide information on the state of other retinal barriers such as the ILM. To study BRB permeability alongside retinal ILM, we used an AAV based method that provides information on permeability of BRB to larger molecules while indicating the state of the ILM and extracellular matrix proteins in disease states. Two AAV variants are useful for such study: AAV5 and ShH10. AAV5&#160;has a natural tropism for photoreceptors but it cannot get across to the outer retina when administered into the vitreous when the ILM is intact (i.e., in wild-type retinas). ShH10 has a strong tropism towards glial cells and will selectively label M&#252;ller glia in both healthy and diseased retinas. ShH10 provides more efficient gene delivery in retinas where ILM is compromised. These viral tools coupled with immunohistochemistry and blood-DNA analysis shed light onto the state of retinal barriers in disease.

To investigate the blood-retinal barrier permeability and the inner limiting membrane integrity in animal models of retinal disease, we used several adeno-associated virus (AAV) variants as tools to label retinal neurons and glia. Virus mediated reporter gene expression is then used as an indicator of retinal barrier permeability.

M&#252;ller cells are the principal glial cells of the retina. Their end-feet form the limits of the retina at the outer and inner limiting membranes ...

Vein Interposition Model: A Suitable Model to Study Bypass Graft Patency

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. Research models for bypass graft failure are essential for a better understanding of pathobiological and pathophysiological processes during graft patency loss. Large animal models, such as pigs or sheep, resemble human anatomical structures but require special facilities and equipment. This video describes a rat vein interposition model to investigate vein graft patency loss. Rats are inexpensive and easy to handle. Compared to mouse models, the convenient size of rats permits better operability and enables a sufficient amount of material to be obtained for further diverse analysis. In brief, the inferior epigastric vein of a donor rat is harvested and used to replace a segment of the femoral artery. Anastomosis is conducted via single stitches and sealed with fibrin glue. Graft patency can be monitored non-invasively using duplex sonography. Myointimal hyperplasia, which is the main cause for graft patency loss, develops progressively over time and can be calculated from histological cross sections.

This video demonstrates a model to study the development of myointimal hyperplasia after venous interposition surgery in rats.

Bypass grafting is an established treatment method for coronary artery disease. Graft patency continues to be the Achilles heel of saphenous vein grafts. ...

Smartphone Fundus Photography

Smartphone fundus photography is a simple technique to obtain ocular fundus pictures using a smartphone camera and a conventional handheld indirect ophthalmoscopy lens. This technique is indispensable when picture documentation of optic nerve, retina, and retinal vessels is necessary but a fundus camera is not available. The main advantage of this technique is the widespread&#160;availability of smartphones that allows documentation of macula and optic nerve changes in many settings that was not previously possible. Following the well-defined steps detailed here, such as proper alignment of the phone camera, handheld lens, and the patient&#39;s pupil, is the key for obtaining a clear retina picture with no interfering light reflections and aberrations. In this paper, the optical principles of indirect ophthalmoscopy and fundus photography will be reviewed first. Then, the step-by-step method to record a good quality retinal image using a smartphone will be explained.

Fundus photography normally requires specialized fundus cameras that are not always available in all clinical settings.&#160;Here, a simple method to record ocular fundus images using a smartphone camera and a conventional high-plus handheld indirect ophthalmoscopy lens is described.

Smartphone fundus photography is a simple technique to obtain ocular fundus pictures using a smartphone camera and a conventional handheld indirect ...

Laser Doppler: A Tool for Measuring Pancreatic Islet Microvascular Vasomotion In Vivo

As a functional status of microcirculation, microvascular vasomotion is important for the delivery of oxygen and nutrients and the removal of carbon dioxide and waste products. The impairment of microvascular vasomotion might be a crucial step in the development of microcirculation-related diseases. In addition, the highly vascularized pancreatic islet is adapted to support endocrine function. In this respect, it seems possible to infer that the functional status of pancreatic islet microvascular vasomotion might affect pancreatic islet function. Analyzing the pathological changes of the functional status of pancreatic islet microvascular vasomotion may be a feasible strategy to determine contributions that pancreatic islet microcirculation makes to related diseases, such as diabetes mellitus, pancreatitis, etc. Therefore, this protocol describes using a laser Doppler blood flow monitor to determine the functional status of pancreatic islet microvascular vasomotion, and to establish parameters (including average blood perfusion, amplitude, frequency, and relative velocity of pancreatic islet microvascular vasomotion) for evaluation of the microcirculatory functional status. In a streptozotocin-induced diabetic mouse model, we observed an impaired functional status of pancreatic islet microvascular vasomotion. In conclusion, this approach for assessing pancreatic islet microvascular vasomotion in vivo may reveal mechanisms relating to pancreatic islet diseases.

Laser Doppler: A Tool for Measuring Pancreatic Islet Microvascular Vasomotion In Vivo

Pancreatic islet microvascular vasomotion regulates islet blood distribution and maintains the physiological function of islet &#946; cells. This protocol describes using a laser Doppler monitor to determine the functional status of pancreatic islet microvascular vasomotion in vivo and to assess the contributions of pancreatic islet microcirculation to pancreatic-related diseases.

As a functional status of microcirculation, microvascular vasomotion is important for the delivery of oxygen and nutrients and the removal of carbon ...

Conducting Maximal and Submaximal Endurance Exercise Testing to Measure Physiological and Biological Responses to Acute Exercise in Humans

Regular physical activity has a positive effect on human health, but the mechanisms controlling these effects remain unclear. The physiologic and biologic responses to acute exercise are predominantly influenced by the duration and intensity of the exercise regimen. As exercise is increasingly thought of as a therapeutic treatment and/or diagnostic tool, it is important that standardizable methodologies be utilized to understand the variability and to increase the reproducibility of exercise outputs and measurements of responses to such regimens. To that end, we describe two different cycling exercise regimens that yield different physiologic outputs. In a maximal exercise test, exercise intensity is continually increased with a greater workload resulting in an increasing cardiopulmonary and metabolic response (heart rate, stroke volume, ventilation, oxygen consumption and carbon dioxide production). In contrast, during endurance exercise tests, the demand is increased from that at rest, but is raised to a fixed submaximal exercise intensity resulting in a cardiopulmonary and metabolic response that typically plateaus. Along with the protocols, we provide suggestions on measuring physiologic outputs that include, but are not limited to, heart rate, slow and forced vital capacity, gas exchange metrics, and blood pressure to enable the comparison of exercise outputs between studies. Biospecimens can then be sampled to assess cellular, protein, and/or gene expression responses. Overall, this approach can be easily adapted into both short- and long-term effects of two distinct exercise regimens.

To assess the influence of exercise intensity on physiologic and biologic responses, two different exercise testing protocols were utilized. Methods outlining exercise testing on a cycle ergometer as an incremental maximal oxygen consumption test and endurance, steady state submaximal endurance test are described.

Regular physical activity has a positive effect on human health, but the mechanisms controlling these effects remain unclear. The physiologic and biologic ...

The Dyspepsia Educational Tool As a Novel Aid in Dyspepsia Management

Digital educational tools have a well-established role in current healthcare. In particular, disorders that are managed non-pharmacologically benefit from this development, as it enables patient engagement in self-management. Dyspepsia is a condition thought to arise from gastric and duodenal perturbations, brain-gut axis disturbances, and dietary factors. Behavioral interventions are a major part of dyspepsia treatment, hence patient engagement and motivation through education is essential. Protocols that describe the development process of such educational tools are scarce. We provide a methodology describing development of a dyspepsia educational tool. Assessment of users' needs is the first step, followed by a literature search. The content is developed based on the main themes and entered into a content management system, to build the program. Final adjustments are made after a pilot test of the tool. The presented protocol can be used as a guide for development of a digital dyspepsia educational tool or as a tool for similar situations.

This protocol describes the development process of a digital dyspepsia educational tool. Assessment of unmet needs and literature, content development, and building of the tool are presented. The methodology can be used as a guide for future development of digital educational tools.

Digital educational tools have a well-established role in current healthcare. In particular, disorders that are managed non-pharmacologically benefit from ...

A Cryoinjury Model to Study Myocardial Infarction in the Mouse

The use of animal models is essential for developing new therapeutic strategies for acute coronary syndrome and its complications. In this article, we demonstrate a murine cryoinjury infarct model that generates precise infarct sizes with high reproducibility and replicability. In brief, after intubation and sternotomy of the animal, the heart is lifted from the thorax. The probe of a handheld liquid nitrogen delivery system is applied onto the myocardial wall to induce cryoinjury. Impaired ventricular function and electrical conduction can be monitored with echocardiography or optical mapping. Transmural myocardial remodeling of the infarcted area is characterized by collagen deposition and loss of cardiomyocytes. Compared to other models (e.g., LAD-ligation), this model utilizes a handheld liquid nitrogen delivery system to generate more uniform infarct sizes.

This article demonstrates a model to study cardiac remodeling after myocardial cryoinjury in mice.

The use of animal models is essential for developing new therapeutic strategies for acute coronary syndrome and its complications. In this article, we ...