15 August 2012

Markers, Medals and Math:
Pushing the Envelope

 - Markers

 - “OK for me, but not OK for you.” Before we go to today’s agenda, I’ll just talk a bit about the ractopamine issue mentioned in my previous post. The Member States of Codex Alimentarius Commission adopted maximum residue limits for the amount of ractopamine, the animal growth drug, allowed in the tissues of pigs and cattle. The Codex Commission reached a decision through a vote, carried out in accordance with the Commission’s rules and procedures. The limits were approved with 69 votes for, 67 against, and seven abstentions. The decision was made after the assessment was carried out by the Joint Expert Committee on Food Additives (an arm of the FAO/WHO) and reached after a rigorous process of scientific assessment to ascertain that the proposed levels of residues have no impact on human health.

 - Without going into statistical elaborations and disrespecting committee members, or committee rules, we notice that it was not an overwhelming vote. Will a 2-vote difference (among 143 individuals) make the score and tell us that it’s totally “safe” to ingest ractopamine-fed animal products? We’re dealing with world health- our health. And yet we single-out and penalize an Olympic athlete for using performance enhancing drugs. Why the disparity in decision making? Honestly, this is a bit absurd. One might argue that the two situations are different from one another. However, I believe that the WHO, and whoever is deciding for our health outcomes, should adopt a policy that is consistent in all settings. Not, “OK for me, but not OK for you.” I’ll leave you with that food for thought.

For more information please contact:

Glenn Thomas
WHO, Geneva
Mobile: +41 79 509 0677


 - Biomarkers of Human Health


 - A biomarker, or biological marker, is an indicator of a biological state. It is a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. It is used in many scientific fields. This marker can be found in a specific tissue, organ, or throughout the body. It is an index of either health or disease. It is meant to detect the smallest unit of a certain molecule, or process (as in the electrocardiogram) in the body. 


 - While we know of blood cholesterol levels and traces of zinc in the skin and nails, growth of the knowledge and the technology to asses these elements is expanding remarkably. Now, with the growth of genomics and Medical Information Technology, we are delving deeper, not only with one person’s health, but also with the likelihood of disease in his or her offspring. It is not sufficient to identify a molecule’s presence. We are also measuring their specific levels. Laboratories are currently facing the recession, and because of this we have to work smarter. For example, we could use mathemathical modeling and organ simulation in order to minimize animal or human experimentation whenever feasible. Chemical reagents and the sundry materials of the lab are getting way expensive. It would be possible to buy special computer programs for our particular area of study. If the program is not available, well, we can code one. A bit of study and a bit of practice go a long way. Oh yes, time is gold. If we can plan our experiments well beforehand (with the proper tools), we could save on energy and even possible mistakes.We should make use of the ELN (Electronic Laboratory Notebook) to log all our observations througout the experiment. It is a way of maximizing our observations and calculations thereby enabling us to see the minutiae as well as the bigger picture.

 - Math


 - Different computer programs are now increasingly used to assess the significance of certain health data. One such program is MATLAB, a mathematical analysis tool that is used in cases ranging from aerodynamic data to abnormal physiological signals. The book by Steven C. Chapra, “Applied Numerical Methods with MATLAB - for Engineers and Scientists”, is a good resource dealing with computers: MATLAB features, computer uses and their limitations in the scientific field. In this day and age, to eschew information technology is a major offense. This also holds true in the health professions. With the increasing portability of data access, we have to make some notable changes in our diagnostic attitude. Physicians and nurses are tapping into servers and cloud engines to support their skills and acumen. The advent of telemedicine is further strengthening the role of health computing machines in the workplace and wherever the patient may be. 


 - It’s not enough, though, to record signals or biologic phenomena. It is also  imperative that we study and make this data relevant to our roles as purveyors of health. How we carry out our analysis will matter in the ways that data is relevant in an individual in a given situation. In other words, it’s not just about collecting and storing data, but rather understanding and making decisions that will impact your health. Statistics, time-series analysis, signal processing, and biophysics simulations are all important analytic processes. While it is true that there may are special departments devoted to these applications, we must be cognizant of their operations. The whole process eventually depends on the algorithms used in the analysis of the data. Whether one is a clever clinical diagnostician or a computer programmer, the formulas we utilize can spell the difference in the diagnosis between a gastric reflux state, and a case of an impending myocardial infarction. Obviously, we may not have time to review calculus and other maths in an acute and potentially catastrophic 50/50 situation. That is why we should take as much time honing our tech skills as we do our daily SOP (standard operating procedures). 


 - Actually, all this study is a definite load on the time and energy of health practitioners. That is why we should accept this responsibility and work more efficiently. If not, we will all burn out eventually and that will put us out of reach with the patient After many years dealing with critical cases in the ICU/CCU, it has become second nature to me to make the most reasonable choices in a given situation. But it is not boasting, but rather accepting that our competence relies heavily on our clinical and technical aptitude. Now, we have associations dealing with Medical Information Systems, and we have access to the surmounting knowledge that is paving the way to a better health experience. 


 -In the following days and weeks, I will be demonstrating to you certain ways of computer-based math in the diagnostic arena. Our bodies are mysterious temples with many hidden corridors and alleys. It is now our time to unravel bit by bit what stuff we are made of. At the same time, we will be exercising our frontal lobes. It's not just calculating numbers, but rather picturing the process in our minds. Or, pen it at the back of an envelope if you have one. If you've got a mobile device with a stylus, that would be nice. It's good to remember that math is basically the relationships between objects.

 - Stuff for Exercise
 - A Formula for Vascular Resistance: Standard Fluid Dynamics

 - We begin with the Hagen–Poiseuille equation, a physical law that gives the pressure drop in a fluid flowing through a long cylindrical pipe. The assumptions of the equation are that the fluid is viscous and incompressible; the flow is laminar through a pipe of constant circular cross-section that is substantially longer than its diameter; and there is no acceleration of fluid in the pipe. The equation is also known as the Hagen–Poiseuille law, Poiseuille law and Poiseuille equation. Actual fluid flow is turbulent (i.e., not laminar) for velocities and pipe diameters above a threshold, leading to larger pressure drops than calculated by the Hagen–Poiseuille equation. In the blood vessels, you have turbulence at bifurcations or stenosis. The change in flow can give rise to Eddy currents (also called Foucault currents). The term eddy current comes from currents seen in water when dragging an oar breadthwise. These localized areas of turbulence known as eddies give rise to persistent vortices. Any spiral (or, spinning) motion with closed streamlines is vortex flow. In cardiology, eddy currents are important because these areas of spinning can facilitate the formation of thrombi. Blood flow in the opposite direction from normal is regurgitation. Alright, so now we begin our exercise.

1) To start: on the left is the first formula to take a good look at;

2) Try to determine the unit of measurement for the variables, such as P, L, and so on;

3) What would be the usual and reasonable limits for each of the variables;

4) Calculate.

Since we are dealing now with blood vessels, remember the characteristics of the vessel,
(e.g. artery or vein) and understand the different agents that may influence the characteristics, (e.g. hormones, blood gases, electrolytes).

 - In the process you will be reviewing anatomy, physiology, biochemistry, and biophysics. Grab your favorite calculator and try it out. We will continue next time...

 - Stay cool! See you.

 - Fernando Yaakov Lalana, M.D.

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