Sensing oxygen – Leland Clark and the origins of direct oxygen measurement in blood

As we’ve all been back from AHA19 for a few weeks now, I began thinking about the research presented. Throughout the conference I tried to focus on topics of aging and cardiovascular disease, which is my current research focus. I kept finding myself in front of posters or at talks on metabolism and my personal favorite organelle, the mitochondria.

I’ve been fascinated by mitochondria since graduate school where I ran ~300 Seahorse assays on clinical samples among other mitochondrial measures. To be clear, I was a bit burnt out on the Seahorse after my PhD but that feeling has faded. These oxygen consumption assays to measure mitochondrial function have gained popularity in recent years, which got me thinking about the origins of these devices.

The first measures of oxygen tension in blood were developed by Leland Clark1. A major limitation of measuring oxygen tension in solutions was that the liquid needed to either be quiescent or constantly stirred, which limited the use in vivo1.

Dr. Leland Clark

Dr. Leland Clark2 (https://en.wikipedia.org/wiki/Leland_Clark#/media/File:Dr._Leland_C._Clark_Jr_2005.jpg)

Measurements I blood, which would be clinically useful, were difficult because tissues were constantly moving. Leland Clark overcame this by developing the polarographic electrode, now termed the Clark Electrode1. This became the foundation for measures of oxygen consumption rate that is the gold standard measure of mitochondrial function in isolated tissue. These are now used in the Seahorse respirometer and the Oroboros oxygraph, the 2 most popular commercial respirometers.

Polarographic oxygen electrode

Polarographic oxygen electrode1 (https://www.physiology.org/doi/pdf/10.1152/jappl.1953.6.3.189)

The development of the Clark Electrode allowed surgeons to have immediate measurements of blood oxygen during surgery, which allowed for open heart surgeries. Dr. Clark not only developed the Clark Electrode, he helped to develop the glucose monitor, which is still critical for many diabetic patients to monitor their care. He also helped to develop the first heart-lung machine helped pave the way for one of the first intensive care units in the world3.

While Dr. Clark was more concerned with measuring oxygen saturation in blood to improve direct patient care, he didn’t realize that he would also greatly advance the field of metabolism by allowing for accurate measurements of mitochondrial function. I personally owe Dr. Clark a debt of gratitude because I wouldn’t be where I am today without his pioneering inventions.



  1. https://www.physiology.org/doi/pdf/10.1152/jappl.1953.6.3.189
  2. https://en.wikipedia.org/wiki/Leland_Clark#/media/File:Dr._Leland_C._Clark_Jr_2005.jpg
  3. https://www.ysi.com/about/history


The views, opinions and positions expressed within this blog are those of the author(s) alone and do not represent those of the American Heart Association. The accuracy, completeness and validity of any statements made within this article are not guaranteed. We accept no liability for any errors, omissions or representations. The copyright of this content belongs to the author and any liability with regards to infringement of intellectual property rights remains with them. The Early Career Voice blog is not intended to provide medical advice or treatment. Only your healthcare provider can provide that. The American Heart Association recommends that you consult your healthcare provider regarding your personal health matters. If you think you are having a heart attack, stroke or another emergency, please call 911 immediately.


Finding your way at a large national conference: tips and tricks

Attending a scientific conference can be daunting, especially for trainees. You’re still getting your sea legs so-to-speak with regard to your science, and on top of that, you may be presenting a poster or talk to an audience of the most distinguished researchers in your field. Many of us feel the same way, and it can be difficult to muster the courage to go up to someone and introduce yourself. But this is the perfect time to do it!

To really make the most out of your conference experience, especially at a large meeting like AHA Scientific Sessions, it is important to prepare ahead of time! Yes, you will need to book your flight and hotel and register for the conference itself, but you also need to consider how you’re getting to the airport or how you’re getting from the airport to your hotel. Do you know if there is a special lot for rideshare pickups or are you getting a shuttle? Does your hotel offer early check-in? These are all important questions, and at least in my experience, are often overlooked. Plan ahead for the little details, so your brain can be as stress-free as possible on the day of your travel.

Next, to the conference itself. Plan which sessions that you want to go to, but don’t overbook yourself. Scientific conferences often have some downtime, but perhaps you want to get a little exercise while you’re away or if you plan to get a late dinner with colleagues, you might want to skip the early-morning session. Find out what works best for you, so that you can focus on the science and network without feeling completely drained.

Planning which sessions you want to attend can be extremely important for poster presentations. Often, there are so many posters that you won’t have time to wander up and down the entire exhibit hall perusing at your leisure. Search the program using keywords and make a list of a handful of posters you’d like to see. Or if you have a colleague presenting a poster, do them a favor a pay a visit. If they have legions of people trying to get a glimpse of their work, then move on, but if they’re waiting and nobody is talking with them, go up and talk. It can be extremely isolating to stand next to a poster waiting anxiously for someone to come by and show interest.

One great way to get to know more people in any scientific society is to get involved. If you’re a trainee, there is usually some standard way that you can volunteer to join a committee. In AHA, you can apply to be an early career blogger! This is a surefire way to meet people. This serves many purposes. It helps the society in various ways. It also helps your CV. Finally, you are forced to meet and interact with people, many of whom may be in leadership roles. Knowing people at the conference you’re attending is a great way to boost the number of people that come to your poster or presentation and generally improves your conference experience.

My last tip is to have fun. If you use your time wisely, you can come away from a conference with a head full of new ideas in addition to some new friends.



The views, opinions and positions expressed within this blog are those of the author(s) alone and do not represent those of the American Heart Association. The accuracy, completeness and validity of any statements made within this article are not guaranteed. We accept no liability for any errors, omissions or representations. The copyright of this content belongs to the author and any liability with regards to infringement of intellectual property rights remains with them. The Early Career Voice blog is not intended to provide medical advice or treatment. Only your healthcare provider can provide that. The American Heart Association recommends that you consult your healthcare provider regarding your personal health matters. If you think you are having a heart attack, stroke or another emergency, please call 911 immediately.


Haemostatics: Stephen Hales and the first direct measurement of blood pressure

Blood pressure lowering medications are among some of the most effective and useful medications currently used in medicine. In 2017 the ACC/AHA released new guidance for the evaluation and management of high blood pressure in adults.1 This guidance outlines what is considered normal, elevated, and hypertension in adults.1 We now understand the great importance of blood pressure in health but this wasn’t always the case.

As far as we know, blood pressure was first mentioned by G. Harveo (1628) where he warned surgeons that blood could “jet out” of the artery.2 What I was interested in was the first measurement of blood pressure as we know it. That first measurement was done by Reverend Stephen Hales in 1733.2

I remember learning this during undergrad, and the image is striking. It is a picture of Hales and his associate with a horse laying on its side. They inserted a brass tube into the femoral artery connected to a glass tube running vertically out of the horse’s neck.3 The blood reached 8 feet 3 inches.4 Further work by Hales and others went on to describe blood pressures in different species and different vascular beds, but I haven’t been able to get the image of this horse out of my head.2




As my last post for the AHA Early Career Bloggers, I wanted to look into Stephen Hales. Who was he? Why did he do this experiment in the horse? And what else did he do? Hales was a Reverend in Middlesex who dabbled in many scientific pursuits. What I was interested in were those pertaining to the cardiovascular system. I went directly to the source: Statical Essays Containing Haemastatics.4

4 https://books.google.com/books?id=uDQ-AAAAcAAJ (eBook)

4 https://books.google.com/books?id=uDQ-AAAAcAAJ (eBook)


To get some context, this is what was thought about the cardiovascular system of arteries and veins at the time, “As an animal body consists not only of a wonderful texture of solid parts, but also of a large proportion of fluids, which are continually circulating and flowing, through and inimitable embroidery of blood vessels…it has, ever since the important discovery of the circulation of the blood, been looked upon as a matter well worth the inquiring into, to find the force and velocity with which these fluids are impelled…”4

This book doesn’t have any illustrations, unfortunately, but there are descriptions of the many experiments Hales performed. He repeated his experiment on pressures in the horse several times. In fact, the famous image of Hales with the horse was from his 3rd horse experiment. Eventually Hales started collecting the blood and determining how much there was in addition to pouring wax into the empty heart to make a cast and determine the chamber volumes. He compiled this into a pair of tables. 4

4 https://books.google.com/books?id=uDQ-AAAAcAAJ (eBook)


Based on Hales’ measures, he calculated that “a quantity [of blood] equal to the dog’s weight, will pass through the heart in 11.9 minutes”. You’ll notice that Hales made calculations for “Man” but these were derived from data from the other animals and he never performed these experiments on humans.4

Stephen Hales contributed to science in many ways including in other fields. He is famous for inventing a ventilator that circulated air in ships, prisons, and mines which likely saved many lives. Hales had no medical training. He obtained a bachelors degree in divinity and a Master of Arts. Hales is a reminder that great discoveries can be made by anyone with a curious mind.5

4 https://books.google.com/books?id=uDQ-AAAAcAAJ (eBook)

4 https://books.google.com/books?id=uDQ-AAAAcAAJ (eBook)


Don’t forget to register for #Hypertension19 happening this September 5-8 in New Orleans! 



  1. https://www.heart.org/-/media/data-import/downloadables/hypertension-guideline-highlights-flyer-ucm_497841.pdf
  2. The history of blood pressure measurement: from Hales to our days. V.A. Tsyrlin, M.G. Pliss, N.V. Kuzmenko. April 2016. Arterial Hypertension.
  3. http://www.epi.umn.edu/cvdepi/wp-content/uploads/2011/05/Hales-Horse.jpg (http://www.epi.umn.edu/cvdepi/essay/reverend-stephen-hales-on-blood-pressure/)
  4. Stephen Hales. Statical Essays Containing Haemastatics. (eBook: https://books.google.com/books?id=uDQ-AAAAcAAJ
  5. https://en.wikipedia.org/wiki/Stephen_Hales



Carl Wiggers – A Pioneering Figure in Cardiovascular Physiology

In my previous post about the history of AHA research grants, I became interested in another early figure within the AHA, Carl J. Wiggers. He was an Albert Lasker Award winner as well as the first editor-in-chief of the AHA journal Circulation Research. He was a fascinating figure.

Carl Wiggers

Source: National Academy of Sciences1: http://www.nasonline.org/publications/biographical-memoirs/memoir-pdfs/wiggers-carl.pdf


Dr. Wiggers was born in Davenport, Iowa, USA in 1883 and showed promise in academics early. His high school teachers prodded him to pursue medicine. He couldn’t afford 4-years of college, so he chose to attend the University of Michigan over Johns Hopkins Medical School. At the time U of M only required a high school diploma, while JHU required a college degree. This is the Medical School building at the time (now the School for Natural Resources and the Environment).1

medical school

“Medical School; BL004458.” http://quod.lib.umich.edu/b/bhl/x-bl004458/bl004458. University of Michigan Library Digital Collections. Accessed: July 15, 2019.


During medical school, Dr. Wiggers was offered a paid student assistantship in physiology to perform research, and upon graduation from medical school in 1906, he was promoted to an instructor in physiology.1 In 1912, Wiggers traveled to German to study with Prof. Otto Frank.

Wiggers apparently smuggled some of Frank’s designs back to his lab in the USA, now at Cornell.2 Wiggers wanted to improve the measurement of blood pressure and intended to use Otto Frank’s reflecting mirror monometer, eventually developing a portable version to bring to the patient’s bedside.1

Although World War I was raging, in 1918, Carl Wiggers was persuaded to accept a position at Western Reserve (now Case Western Reserve) University where he remained throughout his career. Here he could establish his own cardiovascular research center.1

In 1952, the American Heart Association asked Wiggers to organize and edit a new journal focused on basic research on fundamental studies of the cardiovascular system, Circulation – Research.1 The first issue was published in 1953 as Circulation Research (no hyphen) and quickly positioned the journal as a leader in cardiovascular research.3


Circulation Research

Origin and Early Years. Arnold M. Katz. Circulation Research.3 2001;88:1105–1111. https://doi.org/10.1161/hh1101.091991


At Western Reserve, Wiggers published over 400 original manuscripts and was instrumental in the career of many individuals including Nobel Prize winner Corneille Heymans in 1930. He was committed to training so much so that he often granted sole authorship to early investigators to further their careers.1

Wiggers is famous for his Wiggers Diagram as well as being a member of the National Academy of Sciences, an AHA Gold Hear Award recipient, and Lasker Award winner.1 He was a pioneer in physiology who continues to have a lasting impact today.

aortic blood momentum

Wikipedia.4 Modified from ugawara M, Uchida K, Kondoh Y, et al. Aortic blood momentum–the more the better for the ejecting heart in vivo? Cardiovasc Res 1997; 33(2): 433–46)



  1. Eugene M. Landis. 1976. Carl John Wiggers 1883-1963. National Academy of Sciences www.nasonline.org/publications/biographical-memoirs/memoir-pdfs/wiggers-carl.pdf
  2. Am J Physiol. 1998 Apr;274(4):L467-74. doi: 10.1152/ajplung.1998.274.4.L467.
  3. Origin and Early Years. Arnold M. Katz. Circulation Research. 2001;88:1105–1111. https://doi.org/10.1161/hh1101.091991
  4. Wikipedia. Modified from ugawara M, Uchida K, Kondoh Y, et al. Aortic blood momentum–the more the better for the ejecting heart in vivo? Cardiovasc Res 1997;

The History of the AHA

Following up on an earlier post about the history of the NIH R01 grant, which morphed into a history of the NIH and the National Cancer Institute, I wanted to find out more about the history of the American Heart Association and the first AHA research awards.

This was much easier information to obtain! It is on the AHA website. The first award went to biochemist, Dr. Albert Szent-Gyorgyi, who was fascinating and possibly the topic of a future post. He received the first AHA grant in 1948 while he was at the Marine Biological Laboratory in Woods Hole, MA. He primarily contractile components of muscle including the heart.

Dr. Albert Szent-Gyorgyi (https://en.wikipedia.org/wiki/Albert_Szent-Gy%C3%B6rgyi)


The first AHA logo

The first AHA logo (https://www.heart.org/en/about-us/history-of-the-american-heart-association)

Easily finding this answer led to another question. When and how did the AHA begin in the first place? The public and physicians knew little about cardiovascular diseases in the early 1900’s when the AHA was founded. Heart disease was thought to be a slow, drawn-out death sentence. A group of 6 physicians believed that with scientific research, a cure could be found.

One of the first AHA meetings.

One of the first AHA meetings.(https://www.heart.org/en/about-us/history-of-the-american-heart-association)


The 6 founding members of the AHA were: Drs. Lewis A. Conner, Robert H. Halsey, Paul D. White, Joseph Sailer, Robert B. Preble, and Hugh D. McCulloch. Since the founding in 1924, the AHA’s has been primarily a scientific association. After awarding the first research grant in 1948, AHA began publishing its first journal Circulation in 1950.

From that point on, the AHA was instrumental in funding research that linked smoking and saturated fats to heart disease. AHA research was instrumental in the development of implantable pacemakers, CPR, artificial heart valves, statins, and AEDs. They also established a personal favorite of mine, the Jump Rope for Heart, which I proudly participated in as a child.

There were several changes geared toward unifying the AHA’s objectives, research standards, and guidelines through the years. In 1995, the AHA declared its strategic driving force: Providing credible heart disease and stroke information for effective prevention and treatment. The AHA still functions as a scientific organization but one that faces first and foremost on the public. The AHA’s driving force guides the scientific efforts of AHA members to public benefit.


Are you an AHA member and interested in applying for a research program or award?

The AHA is now accepting applications for four research programs:

  1. AHA Predoctoral Fellowship
  2. AHA Postdoctoral Fellowship
  3. Merit Award
  4. Institutional Undergraduate Program


  • Merit Award Letter of Intent (required) – July 11, 2019
  • AHA AIREA Award – July 17, 2019
  • Predoctoral Fellowship – August 14, 2019
  • Postdoctoral Fellowship – August 15, 2019
  • Institutional Undergraduate Fellowship Program – September 18, 2019

The Grants@Heart or AHA Application Information web page will contain updates about subsequent programs and you can begin preparing your application. Email  apply@heart.org or call 214- 360-6107 for questions.


The History of the Western Blot

Everybody has a western blot horror story. The history of the western blot. What has been your worst western blot experience?

Most basic scientists have done countless western blots in the lab. The western blot, or SDS PAGE and immunoblot, technique is indispensable in most labs as a method to measure relative expression level of your protein of interest. As an early career scientist, I’ve done hundreds of western blots, and I often wonder who came up with this technique.

When I was learning this technique in grad school, I was told that it is called a “western” blot because the precursor techniques for detecting DNA and RNA in gels were called the “southern” blot and “northern” blot. The southern blot being named after Edwin Southern.

This was actually very easy to find out. I went to the references section of the “Western Blot” Wikipedia page and found the first citation for the technique (not yet called a western blot). There were two papers published in 1979 on the technique by different groups. The first was by Jaime Renart, Jakob Reiser, and George Stark in July. The second paper by Harry Towbin, Theophil Staehelin, and Julian Gordon was published in September, and both papers were published in the Proceedings of the National Academy of Sciences of the USA.1,2

According to PNAS, the Towbin paper has over 43,000 citations while the Renart paper has only 493. Both papers undoubtedly have had a much wider impact but most current papers do not cite these originals anymore. A pubmed search for the terms “western blot” or “protein immunoblot” returns a combined 130,000 papers.1,2

The main difference between these two manuscripts was that the Renart technique transferred the proteins from the SDS gel into paper whereas the proteins were transferred into nitrocellulose in the Towbin paper. Now nitrocellulose is used and many use PVDF membranes; however, different labs have different preferences.

The original assembly from the Towbin paper was very simple and not much different from the more sophisticated apparatus marketed by biotech companies today.

Towbin H, Staehelin T, Gordon J. Proc Natl Acad Sci U S A. 1979 Sep;76(9):4350-4.

Towbin H, Staehelin T, Gordon J. Proc Natl Acad Sci U S A. 1979 Sep;76(9):4350-4.

The Renart paper shows blots probed with specific antisera and they look remarkably like blots shown in manuscripts today. The Towbin paper is remarkable because the authors then go on to show a variety of ways this technique can be used. They ran a 1-dimensional gel and stained all of the protein, in this case 60-S ribosomal proteins from chicken liver. Then they ran a 2-dimensional gel (shown below) of the same 60-S ribosomal proteins from chicken liver. Finally, they used antibodies to detect specific proteins and they demonstrated this using both horseradish peroxidase (HRP) and fluorescein (FITC).

Renart J, Reiser J, Stark GR. Proc Natl Acad Sci U S A. 1979 Jul;76(7):3116-20.

Renart J, Reiser J, Stark GR. Proc Natl Acad Sci U S A. 1979 Jul;76(7):3116-20.


Towbin H, Staehelin T, Gordon J. Proc Natl Acad Sci U S A. 1979 Sep;76(9):4350-4.

Towbin H, Staehelin T, Gordon J. Proc Natl Acad Sci U S A. 1979 Sep;76(9):4350-4.

This technique was officially coined “western blotting” in 1981 in a paper by W. Neal Burnette.3 While the name of the western blot is not very important, the technique is obviously one of the most valuable tools for molecular biologists, and one that provides constant amusement (or frustration) for graduate students and post-docs worldwide.

I have many of my own tips and tricks for western blotting but I won’t list them here. Everyone has their own western blot horror stories. One of my worst experiences is mixing up the red and black wires and seeing my precious samples running up and out of the wells, and if you use pre-cast gels which are available from several suppliers, please be kind to them. Don’t squeeze them:


Daniel Tyrrell, 2018, LC3 I and II western blot

Daniel Tyrrell, 2018, LC3 I and II western blot



  1. Renart J, Reiser J, Stark GR. Proc Natl Acad Sci U S A. 1979 Jul;76(7):3116-20.
  2. Towbin H, Staehelin T, Gordon J. Proc Natl Acad Sci U S A. 1979 Sep;76(9):4350-4.
  3. Burnette WN. Anal Biochem. 1981 Apr;112(2):195-203.





The First Funded R01 Ever

The first two extramural grants for a research project (the precursor to today’s R01) were given on March 21, 1938 to Dr. John Bittner at Jackson Laboratory (then, the Roscoe B. Jackson Memorial Laboratory) in Bar Harbor, Maine for his work on breast cancer1,2.

Bittner J. Mammary Tumors In Mice In Relation to Nursing. Cancer Research. 1937;30(3).

Bittner J. Mammary Tumors In Mice In Relation to Nursing. Cancer Research. 1937;30.

One grant for $3,200 was awarded directly to Dr. Bittner, and the other for $9,900 was awarded to the Roscoe B. Jackson Memorial Laboratory by the National Cancer Institute. These first “R01-type” awards were given by the NCI from 1938-1943, and in that time, 65 grants-in-aid were paid2.

Marshino O. Administration of the National Cancer Institute Act, August 5, 1937, to June 30, 1943. JNCI: Journal of the National Cancer Institute. 1944:429-43.

Marshino O. Administration of the National Cancer Institute Act, August 5, 1937, to June 30, 1943. JNCI: Journal of the National Cancer Institute. 1944:429-43.

In the early days of extramural grants in the USA through the 1970’s, most awards were Program Projects, Centers, and Development grants. The NIH preferred to grant awards for multidisciplinary centers to carry out a range of projects in a certain area of interest. It wasn’t until after Watergate and Nixon’s resignation that Investigator-Initiated Research Projects (R01) began to dominate large Program-Project grants (P01)3.

To understand the path from these first grants to today’s R01’s, it is important to understand the history of the NIH. The Hygienic Laboratory became the NIH in 1930 with the passage of the Ransdell Act, and the NCI began with the National Cancer Institute Act in 1937. The NCI could administer extramural grants for research on cancer, but the NIH at large could not3.

The federal government greatly increased research spending in medical research during World War II, and when the war was over, both the government and scientists wanted to continue federally funded research. The NIH couldn’t legally administer extramural grants until the passage of the Public Health Service Act in 1944 which consolidated the NCI and NIH under one roof under the Surgeon General.

In 1946 the Research Grants Office was created to administer extramural research grants and fellowships awards. Congressional funding of the NIH increased steadily, and all the while the NIH was adapting its branding by renaming institutions (i.e. changing “National Microbiological Institute” and “Experimental Biology and Medicine Institute” to flashier names like “National Institute of Arthritis and Metabolic Diseases” and “National Institute of Allergy and Infectious Diseases,” which further enticed congressional funding). From 1946 to 1953, the number of funded projects increased from 80 to 2,000 and the funds increased from $780,000 to over $20,500,0003.

Mandel R. A Half Century of Peer Review, 1946-1996: Division of Research Grants, National Institutes of Health. Division of Research Grants, National Institutes of Health; 1996.

Mandel R. A Half Century of Peer Review, 1946-1996: Division of Research Grants, National Institutes of Health. Division of Research Grants, National Institutes of Health; 1996.

In 1946, the NIH Syphilis Study Section had its inaugural meeting. This was the first study section meeting at the NIH4. From this point, more and more study sections met to discuss the state of science and to review grant applications. In 1950, the standardization of study sections began with the assignment of priority scores from 1 to 5. This made it possible to rank grants based on merit for funding.

Mandel R. A Half Century of Peer Review, 1946-1996: Division of Research Grants, National Institutes of Health. Division of Research Grants, National Institutes of Health; 1996.

Mandel R. A Half Century of Peer Review, 1946-1996: Division of Research Grants, National Institutes of Health. Division of Research Grants, National Institutes of Health; 1996.

These changes lessened the workload of study sections initially, but as research design became more sophisticated, more and more of the meeting time was devoted to project discussions3. Eventually, some within the research community became dissatisfied with the closed-door process of grant review. In 1973, the Office of Management and Budget called for the abolishment of study sections, but the acting NIH Director, Dr. John Sherman, defended peer review as the highest priority.

Political events at the time caused turmoil within the NIH. A combination of budget constraints due to the war in Vietnam along with Watergate and procedural confusion and secrecy regarding the peer review process led to a reorganization at NIH. A familiar name, Ruth Kirschstein, director of the NIGMS in 1974, stated, “How can a system, devised in an era of elitism, of secrecy, and of economic growth…be adopted to an era in which stress in on equal opportunity, openness, and limited availability of funds?3.

Mandel R. A Half Century of Peer Review, 1946-1996: Division of Research Grants, National Institutes of Health. Division of Research Grants, National Institutes of Health; 1996.

Mandel R. A Half Century of Peer Review, 1946-1996: Division of Research Grants, National Institutes of Health. Division of Research Grants, National Institutes of Health; 1996.

There was rampant favoritism and bias in the review process, and over the next decade, the NIH worked to standardize peer review practices. This included extending project length beyond 3 years in 1984, scoring grants by percentiles in 1987. In the late 1980’s and through the 1990’s, grant applications could be submitted on discs rather than paper and a centralized database of applications was developed.

While the first grant application wasn’t submitted electronically using the PHS-398 form, it was the first time an NIH institute, the NCI, funded an extramural grant for an individual research project, which we now refer to as an R01.



  1. Bittner J. Mammary Tumors In Mice In Relation to Nursing. Cancer Research. 1937;30(3).
  2. Marshino O. Administration of the National Cancer Institute Act, August 5, 1937, to June 30, 1943. JNCI: Journal of the National Cancer Institute. 1944:429-43.
  3. Mandel R. A Half Century of Peer Review, 1946-1996: Division of Research Grants, National Institutes of Health. Division of Research Grants, National Institutes of Health; 1996.
  4. Pederson T. The “study” role of past National Institutes of Health study sections. Mol Biol Cell. 2012;23(17):3281-4.



A Short History of Immunosuppressants And The Woman Who Invented Them

I’ve been thinking about the field of experimental transplantation research lately. There has been great research in this area recently, including work in Circulation Research on using nanoparticles to target potent immunosuppressants to key areas to suppress rejection (Bahmani, Uehara et al. 2018). There was also an interesting paper that used an aortic arch transplant model to study regression of atherosclerosis published in ATVB (Li, Luehmann et al. 2018). I began thinking about transplantation and the issue of acute rejection. There is also the problem of longer-term chronic vasculopathy and remodeling, but how did the field get over the first hurdle of acute rejection? It’s so fundamental to all organ transplantation that takes place in the clinic today. I decided to look into how we got to where we are today.

I found out that one of the earliest immunosuppressive agents was 6-mercaptopurine (6-MP). 6-MP was developed by a chemist named Gertrude Elion. I was delighted to find out that a woman developed this drug, especially as it was recently Women in Science Day on February 11th. Elion was born in New York City and earned a Bachelor’s degree at Hunter College and a Master’s degree in chemistry at NYU. She submitted 15 applications for graduate fellowships which were all turned down, leading her to enroll in secretarial school. She moved through several other jobs before working in as an assistant at what is now GlaxoSmithKline (GSK). While working there, she began earning her doctorate at night but stopped due to the difficulty of the commute. It was at GSK that Elion developed 6-MP, but she was only getting started.

6-MP was first used in the late 1950’s as chemotherapy to suppress antibody formation in pediatric cancer which improved survival from 3-4 months up to 12 months. 6-MP was next used in rabbits that were injected with bovine serum albumin to stimulate a powerful antigen response, but 6-MP prevented it (Schwartz, Stack et al. 1958). Next, a British surgeon, Roy Calne wanted to test whether 6-MP’s immune suppression could be used to prevent rejection after a transplant. He treated a dog with 6-MP and then transplanted a kidney from another dog. Ordinarily, the recipient dog’s immune system would attack the new kidney as if it were an invader. The kidney in the 6-MP treated dog survived 44 days compared to only 10-days for dogs that weren’t given 6-MP (Calne 1960). This drug seemed promising, but it had a high risk of toxicity, and this is where the story gets interesting.

Roy Calne wanted to find a drug that was as effective as 6-MP but less toxic, so he asked Gertrude Elion. Elion suggested another compound that she had recently synthesized, which was azathioprine (AZA) (Elion, Callahan et al. 1960). Clinicians will be familiar with this drug, but as a PhD scientist, I had never heard of it before now (and I did my PhD in pharmacology, but don’t hold it against me). AZA is a pro-drug that that is activated by glutathione in red blood cells to produce the active metabolite 6-MP in plasma. AZA was not only superior to 6-MP for preventing alloimmune transplant rejection, it was far less toxic. In 1962, only 2 years after the kidney transplant study with dogs, AZA was being used in human kidney transplants together with prednisone (Murray, Merrill et al. 1963). From this point onward, kidney transplants using Gertrude Elion’s AZA compound skyrocketed.

In 1988, Gertrude Elion was awarded the Nobel Prize in Physiology or Medicine, just the 5th woman to receive the award at the time. The development of AZA and more importantly, its use as an immunosuppressive agent allowed for the transplantation of many other organs, including livers, lungs, and hearts (Elion 1989). Other immunosuppressants have been developed which are in use for heart transplantation today but AZA is still being used for kidney transplants and chronic inflammatory diseases like rheumatoid arthritis and Crohn’s disease. Elion’s AZA is also listed as an essential medicine by the World Health Organization.

Gertrude Elion was an amazing scientist that had an enormous impact on health across the world. In addition to the synthesis and development of AZA, she is credited with the synthesis of allopurinol to treat gout and ancyclovir to treat herpes simplex virus. Both of these drugs are classified as essential medicines by the WHO. Her knowledge of both chemical synthesis and the biochemical basis of disease set her apart as a truly remarkable scientist who overcame many obstacles that women in science still face. Gertrude Elion should serve as a role model for anyone interested in science.



“Gertrude B. Elion.” https://en.wikipedia.org/wiki/Gertrude_B._Elion

“Gertrude B. Elion Biographical.” https://www.nobelprize.org/prizes/medicine/1988/elion/biographical/

Bahmani, B., M. Uehara, L. Jiang, F. Ordikhani, N. Banouni, T. Ichimura, Z. Solhjou, G. J. Furtmuller, G. Brandacher, D. Alvarez, U. H. von Andrian, K. Uchimura, Q. Xu, I. Vohra, O. A. Yilmam, Y. Haik, J. Azzi, V. Kasinath, J. S. Bromberg, M. M. McGrath and R. Abdi (2018). “Targeted delivery of immune therapeutics to lymph nodes prolongs cardiac allograft survival.” J Clin Invest 128(11): 4770-4786.

Calne, R. Y. (1960). “The rejection of renal homografts. Inhibition in dogs by 6-mercaptopurine.” Lancet 1(7121): 417-418.

Elion, G. B. (1989). “The purine path to chemotherapy.” Science 244(4900): 41-47.

Elion, G. B., S. W. Callahan, G. H. Hitchings and R. W. Rundles (1960). “The metabolism of 2-amino-6-[(1-methyl-4-nitro-5-imidazolyl)thio]purine (B.W. 57-323) in man.” Cancer Chemother Rep 8: 47-52.

Li, W., H. P. Luehmann, H. M. Hsiao, S. Tanaka, R. Higashikubo, J. M. Gauthier, D. Sultan, K. J. Lavine, S. L. Brody, A. E. Gelman, R. J. Gropler, Y. Liu and D. Kreisel (2018). “Visualization of Monocytic Cells in Regressing Atherosclerotic Plaques by Intravital 2-Photon and Positron Emission Tomography-Based Imaging-Brief Report.” Arterioscler Thromb Vasc Biol 38(5): 1030-1036.

Murray, J. E., J. P. Merrill, J. H. Harrison, R. E. Wilson and G. J. Dammin (1963). “Prolonged survival of human-kidney homografts by immunosuppressive drug therapy.” N Engl J Med 268: 1315-1323.

Schwartz, R., J. Stack and W. Dameshek (1958). “Effect of 6-mercaptopurine on antibody production.” Proc Soc Exp Biol Med 99(1): 164-167.



Turning Back The CLOCK: A Look Into The History of Circadian Oscillations

As an early career researcher, I feel that I lack some critical background knowledge of foundational studies and scientists in research. Most of my blog posts will focus on recent papers or topics, and I’ll dig into the history of that topic to find out how we got to where we are.

Many fantastic papers have been published on the circadian clock lately. Drs. David Montaigne and Bart Staels recently published a Viewpoint on the topic of the circadian clock and cardiovascular disease in Circulation Research.1 My basic understanding of the circadian clock is that transcription factors, CLOCK and BMAL1, are critical proteins. Light is sensed at the retina and the optic nerve transmits a signal to the suprachiasmatic nuclei then throughout the body. Since light (historically) came from the sun, these proteins and the clock functions generally oscillate with day and night. Knocking out or mutating clock proteins can alter metabolism, immunity, and a slew of other systems.

A 2013 paper published in Circulation by Xiaoyue Pan and colleagues showed increased atherosclerosis in mice where the CLOCK protein was mutated, thus disrupting the circadian rhythm.2 The mechanisms appeared to be elevated ApoB48 particles and increased macrophage cholesterol scavenging. In 2009, a Circulation paper by Ciprian Anea and colleagues showed increased collagen deposition and fibrotic remodeling after arterial ligation in the carotid artery of BMAL1 knockout mice.3 Finally, a 2018 Cell Metabolism paper by Carla Winter showed that myeloid cells behave in a circadian fashion.4 These are impressive recent papers, but how did we get to this point? I wanted to gain a better understanding of where the science of biological clocks began.

My first stop was the “circadian clock” page on Wikipedia, but it was lacking any historical context.5 Next, I found a review on Pubmed from 1993 by a scientist named Colin Pittendrigh in the Annual Review of Physiology entitled, Temporal organization: reflections of a Darwinian clock-watcher.6 This review was more of an autobiography than review, but it was a joy to read. I would suggest reading the entire review, but I’m going to summarize some it here. After reading a few paragraphs it became evident that Colin Pittendrigh might be a prominent figure in the science of biological clocks. I did a quick search (the Wikipedia page for “Colin Pittendrigh”) and found this in the second sentence, “…father of the biological clock…”, which came from a Stanford press release upon Pittendrigh’s death.7,8

What I found in Pittendrigh’s 1993 “reflections” was that he was an extraordinary scientist, and an interesting man. Pittendrigh begins by recounting how he became interested in biology. Living in the north of England, he kicked a soccer ball through the window of the town hall and needed to replace it. Needing money, he entered a contest for the best wild flower collection from the local Boy Scouts and won. This sparked his biological interest. During high school, Pittendrigh discovered Charles Darwin’s works which greatly influenced him. He says that his Darwinian beliefs later survived exposure to Lamarckian convictions of a college professor. During wartime in the 1940s, he was in Trinidad and was instructed to focus on breeding vegetables for the campaign. Later, he studied Malaria by focusing on habits of mosquitoes, and eventually he studied drosophila behavior. During these experiences, he observed periodicity in the behaviors of these organisms.6

With influences from colleagues, Pittendrigh reasoned that the biological clock must be endogenous.6 During his time at Princeton and Stanford, Pittendrigh published many papers including five in the journal, Science. Almost all of these were published on the circadian oscillations of plants and animals; however, he had other interests, as well. Notably, a 1965 Science paper titled, Proposed Biological Exploration of Mars between 1969 and 1973.9 Pittendrigh’s career in science was monumental, although he didn’t discover the proteins involved in biological clocks. The CLOCK protein was discovered in 1993 and BMAL1 was discovered in 1997, the year after Pittendrigh’s death.10,11 These discoveries undoubtedly wouldn’t have been made without the pioneering work of Colin Pittendrigh.

Dr. Pittendrigh’s life and discoveries are remarkable and in his writing, he constantly references others that were instrumental to his ideas and discoveries. With mounting pressure to have first or last author publications in our time (forgive the pun), it is easy to overlook others who make scientific progress possible. And although Colin Pittendrigh did not study cardiovascular diseases, his findings are having an impact on cardiovascular medicine now. This highlights the interdisciplinary nature of science and how ideas from diverse fields impacts others. It is always beneficial to read papers, attend seminars, and speak with colleagues from diverse fields to broaden our own experimental approaches and ideas.



  1. David Montaigne & Bart Staels. Time to Check the Clock in Cardiovascular Research and Medicine. Circulation Research. 2018; 123:648–650
  2. Xiaoyue Pan, Xian-Cheng Jiang, and M. Mahmood Hussain. Circulation. 2013 Oct 15; 128(16): 1758–1769.
  3. Anea CB, Zhang M, Stepp DW, Simkins GB, Reed G, Fulton DJ, Rudic RD. Circulation. 2009 Mar 24;119(11):1510-7
  4. Winter C, Silvestre-Roig C, Ortega-Gomez A, Lemnitzer P, Poelman H, Schumski A, Winter J, Drechsler M, de Jong R, Immler R, Sperandio M, Hristov M, Zeller T, Nicolaes GAF, Weber C, Viola JR, Hidalgo A, Scheiermann C, Soehnlein O. Cell Metab. 2018 Jul 3;28(1):175-182.e5
  5. https://en.wikipedia.org/wiki/Circadian_clock
  6. S. Pittendrigh. Temporal organization: reflections of a Darwinian clock-watcher. Annu. Rev. Physiol. 55, 17 16-54. 1993.
  7. https://en.wikipedia.org/wiki/Colin_Pittendrigh
  8. Stanford University News Service. https://news.stanford.edu/pr/96/960325pittendrig.html 1996.
  9. Pittendrigh CS. Proposed Biological Exploration of Mars between 1969 and 1973. Science. 1965 Apr 30;148(3670):667.
  10. King DP, Zhao Y, Sangoram AM, Wilsbacher LD, Tanaka M, Antoch MP, Steeves TD, Vitaterna MH, Kornhauser JM, Lowrey PL, Turek FW, Takahashi JS. Positional cloning of the mouse circadian clock gene. Cell. 1997 May 16;89(4):641-53.
  11. Hogenesch JB, Chan WK, Jackiw VH, Brown RC, Gu YZ, Pray-Grant M, Perdew GH, Bradfield CA (March 1997). “Characterization of a subset of the basic-helix-loop-helix-PAS superfamily that interacts with components of the dioxin signaling pathway”. The Journal of Biological Chemistry. 272 (13): 8581–93.



Trainees and Cardiovascular Conferences

I recently viewed a live-streamed session from the American Heart Association’s Scientific Sessions 2018 from the comfort of my own home, and I also attended (in-person) a scientific conference for a different topic within the same month. I began to think of how scientific societies engage trainees, graduate students, and post-docs at conferences. This is all from my perspective as a post-doc, so my observations should be taken with a grain of salt.

The first thing I noticed is that, in my opinion, PI’s typically outnumber trainees at conferences. This is interesting because most labs usually have one PI and several trainees. You might expect a similar parity at conferences, and I believe the reason that most conferences I’ve attended have fewer trainees is the cost of attending. I have been extremely lucky in finding travel awards to attend conferences, yet there have been several that I wanted to go to or committed myself to attend without having funding to support the trip. This can be extremely stressful and is fairly common because as a trainee, your position is not very stable.

When I was a PhD candidate in 2015, I attended a non-AHA conference. At the conference, I volunteered to be the junior representative for the graduate student/post-doc section of the society. I was elected to the position and had to return to the conference in 2016 to accept and begin my term. I was obligated to attend the conference again in 2017 as I transitioned from junior representative to senior representative and again in 2018 as the outgoing senior representative. That means I was supposed to attend the conference 3 years in a row with no clear funding path to pay for any travel. To top it all off, I graduated with my PhD in 2016, just 3 months prior to the 2017 conference date, with no justification for why my post-doc advisor should pay approximately $1,500 for my expenses to present my graduate work. At the 2018 edition of this meeting, I could finally present my post-doc work and luckily received a travel award to offset the cost of the meeting. To make a long-story simpler, 3 or 4-year conference commitments for trainees can be valuable because over that time period I met and worked with many more senior scientists, but shorter commitments would likely entice more applicants to volunteer and greatly reduce the stress involved.

One of the reasons I was elected to the volunteer position in the first place was because I was one of the only graduate students/post-docs to apply. And when I asked other trainees why they hadn’t applied, most said they would be graduating before the 3-year term finished and they didn’t know what type of lab they would end up in. An alternative option for societies is one that I recently sought out and has been surprisingly refreshing. That is the Early Career Blogger Program from the American Heart Association. To lift the veil a bit, I applied after reaching out to one of last year’s early career bloggers, Shayan Mohammadmoradi, who is now a Senior Early Career Blogger with the AHA. This is a 1-year volunteer position, and while it requires attendance at the AHA scientific sessions (I’m planning to attend in 2019), there are some incentives as an official Early Career Blogger that make it possible to attend. First, the conference registration is covered, and if you want to attend other AHA meetings throughout the year, the registration is covered for those as well. AHA also provides access to live-stream their largest annual conference, Scientific Sessions.

I study cardiovascular diseases in the context of aging, and I think supporting early career professionals is a great strategic plan for AHA or any scientific society from the perspective of aging. Early career professionals eventually become middle- then late-stage career professionals and are the next generation of PI’s. By showing that they value early career scientists, AHA will likely reap the benefit in the future.