Dr. Pooneh Bagher is the Assistant Professor at theTexas A&M Health Science Center, working on several projects for the National Aeronautics and Space Administration (NASA). Dr. Bagher's lab has studied a range of unique vessels that many researchers have not examined before. Her lab is interested in how blood vessels usually function and how they function differently in either disease states or extreme physiological conditions, including spaceflight.

In the past three years, Dr. Bagher and her team have had two distinct areas of focus related to the effects of spaceflight on vasculature. Her group has examined the coronary artery and the angular vein. The latter may play a role in a phenomenon called spaceflight-associated neuro-ocular syndrome, otherwise known as SANS.

SANS is a condition that occurs in astronauts when they are in orbit for long-duration missions. Over this period, astronauts start to have changes in their visual acuity. There have been some studies in astronauts on this phenomenon. However, Dr. Bagher and her colleagues first looked at the vascular function in an animal model following space flight. "We were the first researcher sever to study isolated coronary vessels and angular veins following spaceflight," said Dr. Bagher, lead investigator on this part of the project.

For Dr. Bagher's most recent work, the animal models spent 38.5 days at the International Space Station before they were brought back to Earth to be studied as part of NASA's Vision Impairment and IntracranialPressure program. Each team member was devoted to looking at a different aspect of the study that was broken down into groups; arteries, lymphatics, and veins. The team collectively looked at the vessels that feed and drain the eyes to see what happened during the space flight.

Dr. Bagher's lab has been predominantly using DMT wire myographs in her NASA research. They allow numerous systems to be run in parallel – keeping up with the high demand of samples quickly, which is vital to avoid re-acclimatization of the animal models to Earth's gravity. "We have been using DMT wire myographs since 2015," said Dr. Bagher.

When the first project was launched for NASA, Dr.Bagher's Lab held an extreme throughput as they have 28 myograph chambers at their disposal– ranging from single, dual to 4-channel myograph systems. This is essential for collecting many data quickly, which is a must when doing extensive experiments for NASA.
​
The types of experiments Dr. Bagher and her team perform can be very strenuous. The animal models she works with have been taken to space, and the experiments need to be conducted very quickly upon their return. Her entire setup must be fully functional. "We must have equipment that we can coun ton... the DMT wire myograph system provides that consistency," said Dr. Bagher.

*Mention of a university affiliation does not constitute an endorsement by Texas A&M University of the content, viewpoint, accuracy, opinions, policies, products, services, or accessibility of any external vendor.
 
 
Recent Research
Comparison of Adrenergic and Purinergic Receptor Contributions to Vasomotor Responses in Mesenteric Arteries of C57BL/6J Mice and Wistar Rats
A Mittal, PD Park, R Mitchell, H Fang, P Bagher / Journal of Vascular Research 58 (1), 1-15

Microvascular dysfunction and kidney disease: Challenges and opportunities?
S Krishnan, AD Suarez‐Martinez, P Bagher, A Gonzalez, R Liu, ... / Microcirculation, e12661
Endothelial calreticulin deletion impairs endothelial function in aged mice
LA Biwer, HR Askew-Page, K Hong, J Milstein, SR Johnstone, E Macal, ... / American Journal of Physiology-Heart and Circulatory Physiology 318

​By David Plante | DMT-USA, Inc. | July 2021

A DMT Myograph System is a substantial investment, and maintaining the myograph system is vital to ensure optimal performance, reliability, and output.

Following the maintenance protocols in the user documentation will keep the myograph accurate and reliable for quite a while, with no downtime or failure. However, preventive care reduces the tear and wear of the system, and maintenance can extend the myograph's lifetime. 

The service check consists of;

System dismantles, part cleaning, assembly, lubrication temperature re-compensation of transducers, replacement of internal tubing, calibration, update of firmware *2, functional system test, and documentation. 

The service is performed by certified technicians only, and the turnaround time is typically 4-5 days.

Myograph Maintenance Options

• Myograph Maintenance Service
• Myograph Maintenance – Service Agreement 3-Years *1 
• Myograph Maintenance – Service Agreement 5-Years *1 

Getting your myograph system serviced by DMT during a valid warranty will add one extra year to the warranty.

​Contact us for more information
​
*1 annual service for the duration on the agreement
*2 when possible

Vascular disease is any abnormalities of blood vessels in the body. According to the American Heart Association data, close to 50% of all adult Americans (~100 million people) have the most common form of the vascular disease known as hypertension. Other forms of vascular disease include atherosclerosis, aneurysms, peripheral artery disease, amongst many others. If left untreated, complications from vascular disease could lead to debilitating illnesses such as heart attack, stroke, and even death in some cases. Although progress is being made in unraveling the mechanisms of vascular disease, more still needs to be done. It is imperative, therefore, that novel vascular disease models are studied in preclinical settings to generate new therapeutics. Myography is a state-of-the-art application in the study of vascular disease ex vivo.

Methodology

Myography is simply the study of the velocity of muscle contraction. This technique can be harnessed to measure the force generated when a blood vessel contracts and relaxes under isometric conditions. The generated information can then be used to determine the function and reactivity of blood vessels. Wire myography can be used to study vessels as small as 100 µm to as large as 3 mm in diameter. In brief, vessels are dissected from genetic, transgenic, diseased, or control models, cleaned of adventitia tissues and mounted on wire jaws or steel pins. Mounted vessels are then subjected to a baseline tension, and recordings of force measurement are conducted, and pharmacological effects of drugs can be analyzed. Examples of common vessels used in wire myography studies include conduit arteries such as the aorta, carotid, pulmonary, and some resistance arteries such as mesenteric and cerebral arteries.
​
Pressure Myography is a more physiologically relevant method for assessing functions of small resistance arterioles ex vivo. These small resistance arteries are vital in the modulation of peripheral vascular resistance and blood flow, thereby regulating blood pressure and organ perfusion. To maintain a constant flow, resistance arteries constrict or dilate in response to changes in blood vessel pressure in a process tone as myogenic tone. This autoregulation mechanism results in maintaining a constant flow. To physiologically replicate in vivo vessel conditions in real-time and study resistance arteries using pressure myography, isolated arteries are mounted unto two glass cannulas and pressurized to in vivo pressure. A new development in pressure myography can add a pulse feature to mimic beats per minute (BPM) on the vessel. Under these conditions, vascular and drug effects can then be studied. Using data acquisition software and live tracking, vessel inner and outer diameter and over twenty endpoints are determined under flow or non-flow states. Examples of resistance arteries used in pressure myography include mesenteric, coronary, cerebral arteries with diameters of 100 µm or less.

Conclusion
​
​What myography technique is best for investigators? Is it wire or pressure myograph, or both? Drawing from my fifteen-year experience as an investigator in hypertension research, I have used both wire and pressure myographs in the same laboratory setting. For large conduit vessels such as the aorta, wire myography is ideal for elucidating the mechanical properties of vessels under isometric conditions. For small resistance arteries, pressure myography is ideal to phenotype near-physiological in vivo conditions. Based on their hypothesis and vessel of interest, it is imperative for the investigator to decide if wire or pressure or both could be incorporated in their scientific tool kit.
If you have questions on which methodology is best suited for your study, please contact one of our Scientific Product Specialists.

By Dr. Larry Agbor
Scientific Product Specialist
DMT-USA, Inc.

Our Scientific Product Specialist, Aaron Stupica, gives an overview of the DMT Pressure Myograph System – an ideal system for assessment of vascular structure and function of perfused arteries.

Check out the videos on our YouTube Channel, and make sure you subscribe to get the latest releases.

We are excited to share a new video series, which will provide simple video tutorials on using the DMT systems. In the series, we will cover topics from system overview to experimental examples. Our goal is to provide quick videos that complement our written guides and user manuals.
 
Check out our videos by heading to our YouTube Channel. Make sure you subscribe to get updates when new videos are published.
 
We hope this new video series will be useful in setting up and getting started with your DMT myograph or organ bath system.  

Discover more about our latest features and what was designed to add functionality to the user experience and to make it more intuitive. Live tracking of perfused arteries' vascular reactivity using the DMT Pressure Myograph Systems has never been more simple.

MyoVIEW 5 offers a simple user interface that provides live diameter tracking of perfused arteries. Using accurate edge detection from up to four user-defined zones, MyoVIEW 5 averages the lumen measurements much simpler and more reliable.

Wall structure, wall stress, strain, and myogenic tone are measured, and responses to increases in pressure, flow, and drugs are evaluated regarding vascular diameter changes.

MyoVIEW 5 provides data acquisition, calculations, and export of data for analysis purposes. It even allows you to create advanced calculations to customize your live traces. Add a script, and traces such as strain is live instantly. 

Easy and quick use, allowing full control of many parameters and management of data. Display the screen view as you want – there is complete flexibility to arrange windows neat and save your preferred layout.

Following the outbreak of the Coronavirus and the current pandemic, the safety and security of customers, and employees, and as our top priority. 

We have put in place measures to help minimize the risk of Coronavirus to our employees and their families. All office-based employees are working from home, and those in our production that cannot do so are temporarily suspended from work under the government aid schemes.

To minimize disruptions, we are continuing to operate to the extent possible and can assist with all matters relating to sales and support. Do not hesitate to get in touch.

Stay safe, stay well, and take care.

DMT Management

"Elastic fibers and the mechanics of maturing arteries"
​The presentation entitled, Elastic fibers and the mechanics of maturing arteries, is a more in-depth version of her presentation in the "Vascular Mechanics" session at Vascular Biology 2017 (Monterey, CA; October 15-19, 2017).

Elasticity of the large arteries is determined by the amount and quality of elastic fibers in the wall. Elastic fibers are composed of over 20 different proteins and the contribution of different proteins to arterial wall elasticity is largely unknown. We will present data on how arterial wall elasticity is affected by the loss of specific elastic fiber proteins in newborn and maturing mouse aorta and speculate on how these mechanical changes may lead to pathological remodeling in development and disease.
​
Much of this presentation will refer to her article in the Journal of Biomechanics, "Crosslinked elastic fibers are necessary for low energy loss in the ascending aorta" (2017 Aug 16;61:199-207. doi: 10.1016/j.jbiomech.2017.07.011. Epub 2017 Jul 25).  Here is a link to the abstract of the article.  If you have a subscription to the Journal of Biomechanics, you will have access to the full text. 

We are happy to inform that "Advanced Train Stimulation protocols" – fully flexible train stimulation protocol programming, now have been made possible! ​