Links of interest (September 18-23, 2011)

One day per week, I will post links of research articles and stories related to cerebrovascular physiology, exercise physiology and more general information related to the research world. Enjoy!

Have a nice weekend !

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Grant applications – First experience as a junior researcher

The last couple of weeks (even months!) have been dedicated to grant applications. My first study has been funded, but the grants I received can be considered as minor grants (still I was the PI on those grants). This year, I am going for the home run with submissions to the Canadian Institutes for Health Research (CIHR; operating grant) and to the Quebec Research Funds (FRSQ; Research scholar-Junior 1).

At our Institution, a young researcher who has never received funding from, or submitted applications to, major Institutes or Funds has to submit his/her grant to a local mentoring committee before anything else. Individuals evaluating grants on this committee eventually decide if the application can be submitted, or not, to CIHR or FRSQ. Last year, I did the same exercise. Although the application was well written (according to them, not to me :-)), I didn’t have the opportunity to get pilot data, the year before, to support my grant. Consequently, the committee decided that it would be better for me to submit a grant application next year with pilot data.

So here I am this year with pilot data ! Although I had a solid draft revised by my mentoring committee last year, I took several weeks to refine the draft. I also decided not only to submit the grant application to my mentoring committee but also to 2 other researchers outside my field of interest. The application definitely improved (a lot) through this process. I am not overly confident with this submission though. I know too well how hard it is to receive such funding, especially with a first submission ! However, if my application gets a good score, I will be happy. The grant application was submitted to CIHR on September 13th…Fingers crossed now !

This week, I will complete my first Research Scholar (Junior 1) application to FRSQ. This submission is not intended to fund a study but a research program. This application is submitted in French and I had to get through the same process (mentoring committee) as the grant application to CIHR. The deadline for this submission is October 1st. I am looking forward to get through it to finally do some research!

What will I do as soon as I have completed that submission? I have two papers (one paper as first author and one paper as senior author) that need to be resubmitted as soon as possible!!!!

Links of interest (September 3-9, 2011)

One day per week, I will post links of research articles and stories related to cerebrovascular physiology, exercise physiology and more general information related to the research world. Enjoy!

Have a nice weekend!

Does the perfect journal club exist?

Next week, I will start journal club meetings with graduate students. I began this journal club last year with some success.

How does it look? It is pretty standard actually! The student who has to review the chosen paper get two weeks to prepare himself. Then, following a brief presentation of the study (no more than 10 minutes dedicated to its description), he starts the discussion with the other students. To ensure that everybody follows the discussion, each student has to carefully read three to five additional papers related to the issue(s) presented in the reviewed manuscript.

In the beginning, the first couple of meetings were just fine and interactions between students were interesting. Unfortunately, I soon noticed that the requested readings were not done by all students. Eventually, the quality of our discussions was no longer the same.

Although everybody has busy weeks, I still think that this journal club is an excellent opportunity for students to learn interesting science outside their area of research, new research methods, strengths and weaknesses of a manuscript, etc. However, people need to put the time and efforts to be adequately prepared for these meetings to be useful.

Next week, we will have a journal club that looks like what I described above…but I am always open to suggestions in order to improve the quality of our meetings. Accordingly,  I am very interested in your journal clubs, dear readers!  Can you tell me about your overall experience with these meetings? Also, can you give me details such as the frequency of meetings (one journal club per week or every two weeks?), the kind of articles you are reviewing (for example articles from top tier journals only?), etc. ?

It would be very interesting and helpful to have the viewpoint of both students and supervisors.

Does the perfect journal club exist?

Physiology…the natural home for physiologists worldwide?

I was reading the latest issue of Physiology and in its editorial, Walter Boron presents a vision for the journal. In the first section of the article, he says:

Along with publishing outstanding reviews with compelling artwork, Physiology also attempted to capture the discipline by publishing editorials and by identifying “Highlights from the Literature.” I think that these are important first steps in making this journal the natural home for physiologists. However, I have long wanted Physiology to transition into something of a Nature format, including not just short reviews but also a small number of short, original articles. This last step could complete the process of making Physiology the de facto home of the discipline worldwide.

Physiologists, do you think that this journal has the potential to become the home of the discipline worlwide or you consider that such a journal already exists?

Carbon dioxide, intense exercise and cerebral blood flow and oxygenation

Once in a while, I will blog about studies related to cerebrovascular physiology (as I was doing over at http://www.physiologiste.blogspot.com). However, I will do so exclusively in English. Be indulgent !! My English skills should improve with every post !

If you have an impression of “déjà vu” with the following article, it’s because I have already blogged about it… but in French 🙂

Recent evidence suggests that the reduction in cerebral blood flow and oxygenation could limit exercise capacity. Indeed, if the amount of oxygen in the brain is reduced below a critical threshold, this could negatively influence the ability to generate muscle work.

Arterial carbon dioxide tension (PaCO2) is a potent modulator of cerebral blood flow at rest and during exercise. More precisely, CO2 dilates blood vessels. Accordingly, an important reduction in CO2 levels in the blood, usually observed during intense exercise, is associated with constriction of blood vessels (cerebral vessels included) and consequently, a reduction in cerebral blood flow. This lowering in CO2 levels in the blood is a consequence of hyperventilation.

A research group has therefore decided to study, in 10 athletes (age: 25.9 ± 7.7 years, weight: 71.2 ± 7.7 kg, height: 181.1 ± 7.4 cm), the impact of maintaining the amount of CO2 in the blood (measured by gas exchange: PETCO2) during a maximal exercise test, on middle cerebral artery flow velocity (CBFV;) and on oxygen levels in the brain (specifically in the frontal lobe) while measuring systemic hemodynamics. The measurements obtained during the exercise protocol were compared with those obtained during a second exercise protocol performed by the same subjects, without maintaining the amount of CO2 stable (1).

This figure shows changes in PETCO2, CBFV, frontal lobe oxygen level (delta TSI: Tissue saturation index) , cerebrovascular reactivity (which is the change in CBFV in relation to the change in PETCO2 ) and cerebral vascular conductance (which is the change in  CBFV / blood pressure ratio compared to the change in PETCO2) at different workloads during exercise with (black dots) and without maintaining PETCO2 stable (white dots).

As we can see, maintaining the amount of CO2 stable was associated with a higher cerebral blood flow velocity during intense exercise as compared to the control condition. However, no difference was observed regarding the other measured variables, including oxygen levels in the brain and maximal workload (watts). This study suggests that despite the fact that CO2 is an important modulator of brain perfusion during exercise, it is definitely not the only one!

Thus, preventing a decrease in CO2 during maximal exercise increases blood flow to the brain but doesn’t seem to have any benefit for the amount of oxygen in the brain (frontal lobe). However, as noted by the authors, it must be remembered that the entire blood flow measured in the middle cerebral artery is not completely directed to the frontal lobes of the brain. The latter issue could partly explain the lack of significant impact of CO2 manipulation on this specific variable. Finally, some mechanisms (not measured in this study) such as changes in sympathetic activity, acid-base balance and distribution of cardiac output could also partly explain these results.

Without discrediting the importance of CO2 variations on brain perfusion during exercise, this study demonstrates the complexity of the regulation of cerebral blood flow and oxygenation in exercising humans!

(1) Olin JT, Dimmen AC, Subudhi AW, Roach RC. Cerebral blood flow and oxygenation at maximal exercise: The effect of clamping carbon dioxide. Respir Physiol Neurobiol 175: 176-180 2011. DOI:10.1016/j.resp.2010.09.011