Eating Like a Caveman.

            Every week there seems to be a new trend in diet and proper nutrition. This week’s flavor is the paleo diet. Its philosophy is that we only eat the things that were available to our hunter gatherer ancestors 10,000 years ago. The main argument for this is that, over millions of years of evolution our ancestors who were genetically selected to live as hunter and gathers. Therefore modern day humans should eat as such.

            The first assumption of this is that we have a good idea of what humans ate back then. In reality we don’t really know. What we know are speculations based on location and what was found with human remains. This brings up a second excellent point; people from different parts of the world ate different things. As people and cultures developed so did the things they ate. People from Asia eat drastically different things as people from Africa.

            The biggest flaw I find with this philosophy of eating is that it assumes people stopped evolving 10,000 years ago. If this was the case we would all still be living in caves. As soon as humans developed the domestication of plants and animal, civilization began. The same logic that we evolved to be hunter and gathers has to be applied to the genetic changes caused by the development of modern society. Are the people who are better suited to live in our society more likely to pass on the genes?

            In the end there is no all-inclusive diet that is perfect for everyone. What we eat should be based on good science and not on some fantasy about a lost Stone Age paradise.

Curnoe D. 2014 Nov 30. The Palaeolithic Diet And The Unprovable Links To Our Past IFL Sceince;. Available from: http://www.iflscience.com/health-and-medicine/palaeolithic-diet-and-unprovable-links-our-past

Tackling the Blood Brain Barrier

The blood brain barrier (BBB) is a tried and true protection for the brain from all sorts of chemicals and other molecules that are in the blood.  Brain capillaries shelter the brain by forming a highly selective permeable layer that limit transport via membrane carriers and channels(2).  The lipophilic membrane keeps water soluble molecules without membrane carriers or channels from crossing the barrier and into the brain.  Early anti-histamines were lipid soluble and freely and easily crossed the BBB causing unwanted drowsiness in patients taking these drugs.  By changing the structures of these anti-histamines, making them less lipid-soluble, non-drowsy allergy medicines were developed(2).

Neurobiologists from Genentech in South San Francisco have developed an antibody capable of crossing the BBB and help limit the damage done by Alzheimer’s disease (AD).  The damage to neural function due to AD is caused by the aggregation of protein amyloid-β(1).  Amyloid-β is created by an enzyme called β-secretase 1 (BACE1).  The antibody developed by Genentech binds to an iron transporter called transferrin that typically carries iron across the BBB.  The antibody binds to transferrin, is transported across the BBB and then binds, with a higher affinity, to BACE1, blocking amyloid- β production(1).  Recent studies have shown decreases in plasma levels of amyloid- β up to as much as fifty-percent in mouse and monkey models.

As technology progresses, so will the treatment of pathologies that we previously viewed as death sentences.  As future health care workers, we will be using techniques and ideas that we now only have limited understanding of.  I am very excited to see where medicine will go, but at the same time I have to worry if the technology may ultimately pass me by.  In this career path, we will always be learning and will always be working to provide the best and most successful treatment options for our patients.

Silverthorn DU. 2010. Human Physiology: An Integrated Approach. 5^th ed. California: Pearson Education, INC. 303-305 p.

Reardon S. 2014. Alzheimer's drug sneaks through blood–brain barrier. Nature Publishing Group. Available from: http://www.nature.com/news/alzheimer-s-drug-sneaks-through-blood-brain-barrier-1.16291

Eat Yogurt, Stay Smart

            Diabetes has been on the rise in the US.  Today, more than one million people are diagnosed with diabetes every year.  As the seventh leading cause of death in the US, over 245 billion dollars has been allotted to finding better treatments and possible cures for diabetes.  These are general statistics on diabetes (not specifically type I or type II).

            Yogurt may be a possible preventative measure of diabetes type II.  A study conducted by Dr. Hu found a correlation between eating a serving a yogurt everyday and a decrease risk of having type II diabetes by 19 percent.  Dr. Hu and associates began to pool their data (originally a study trying to find links between dairy products and diabetes) with other researcher’s data and found that overall, eating yogurt had an 18 percent reduced risk of having diabetes.  These findings could conclude that one’s gut microbiota may play a role in preventing diabetes (remember that seminar article about artificial sugars?).

            Beginningin 1990, scientists have started to link memory problems and type II diabetes.  More than thirteen thousand black and white adults ages 48 to 67 were tested for their memory, reasoning, problem solving, and planning using delayed word recall, digit symbol substitution, and word fluency tests. 

            Over the following twenty years, the scientists conducted five periodic examinations, but at the end only approximately six thousand subjects left.  The scientists discovered that people who suffered from a nineteen percent greater cognitive decline compared with those who did not have diabetes.  Poor control of diabetes had an even greater decline in cognitive function compared to those who were able to control their diabetes. 

            Diabetes is linked to impaired blood circulation and the researchers suggested a relationship between memory and thinking impairment to damage in the small blood vessels in the brain.  Thus, diabetes control and prevention may help to protect against later-in-life cognitive decline. 

I am what???

You're a stereo-blind. Wait. What? When I first read those words I thought it was some sort of juvenile insult, but as I read on I became fascinated. Considering my most recent post, "Are we witnessing the next step in human evolution?" (http://physioblogology4.blogspot.com/2014/11/are-we-witnessing-next-step-in-human.html), I figure It would make sense to post about the flip side.

Stereo-blind is no more an insult than "your epidermis is showing"...It is a condition that arises from such ailments as amblyopia, strabismus, optic nerve hypoplasia. Essentially the eyes do not work together and as a result the individually sees in 2D and lacks depth perception. Other than the above conditions, currently there does not seem to be a genetic link such as a gene mutation. It is a structural abnormality and can occur in anyone.  In the picture you can see an example of a seeing in 3D on the Left and 2D on the right.

The good news is it can be corrected. Susan R. Barry not only was stereo- blind for most her life, but found a way to fix it, and see in 3D at the age of 48. 48!! How cool is that?

The funny thing is, you may be stereo-blind and not even know it! As a person gets older, one of their eyes becomes dominant. This phenomenon 

usually happens slowly and the individual does not recognize the change because they know nothing different. A key sign? You go to see "Star Wars: The Force Awakens" in 3D (or any 3D movie) and don't see any thing different. (3D movies are not worth the extra $5 anyway.)

Think you might be stereo-blind? Talk to your ophthalmologist, or take this online test (http://www.mediacollege.com/3d/depth-perception/test.html).

But seriously, if your concerned see your ophthalmologist. 

Resources:

http://www.mediacollege.com/3d/depth-perception/stereoblind.html

http://www.fixingmygaze.com/

http://www.scientificamerican.com/article/seeing-in-3-d/    

What Am I Getting Myself Into?

I would be lying if I said I never questioned my choice to pursue a career in medicine. Given the tremendous financial cost and the overwhelming time commitment, will it actually be fulfilling? How will it affect my quality of life? my personal well-being?

The numbers aren’t in my favor. Burnout – defined as a combination of emotional exhaustion, detachment and a low sense of accomplishment – is prevalent among medical students and practicing physicians alike:

• A 2008 study by Dr. Dyrbye, et al. stated a burnout rate of 49.6 percent among medical students, approximately 10 percent of whom experienced suicidal ideation
• A 2012 Mayo Clinic survey found that 45.8 percent of doctors reported at least one symptom of burnout (Shanafelt 2012).

Unfortunately, over the last decade, burnout rates seem to be trending up rather than down. In true pre-med induced hypochondriac fashion, I fear the worst.

Recent research has found that burnout increases the risk for cardiovascular disease as much as well-known factors like body mass index or smoking (Bailey 2006). Further studies also indicate an increased probability of type II diabetes, male infertility, sleep disorders, and musculoskeletal disorders (Bailey 2006). One possible malefactor: lower cortisol levels.

Cortisol is the primary hormone involved in the body’s stress-response system that helps restrain immune system reactions. Research indicates that elevated cortisol levels due to chronic stress may result in glucocorticoid resistance in which receptors no longer respond to cortisol’s stop signal (Plotnikoff 2007). Over time, cortisol levels may rebound below normal, leaving the body vulnerable to a hyperactive immune response that produces chronic inflammation (Plotnikoff 2007). Such an inflammatory process is linked to the pathogenesis of other chronic diseases, including depression, and may produce a vicious positive feedback loop.

Antioxidant supplements are said to help lower cortisol levels and may be suggested as an initial preventative measure. But it isn’t that simple. For example, a 2004 study for the Cochrane Database linked increased mortality with supplemental vitamins A, C, E and beta carotene, and selenium (Offit 2013).

The medical field can’t support a burnout rate this high and climbing, it impacts everything from quality of teaching to quality of life for physicians and increases the likelihood of error in patient care. So what do we do? What structural or systemic changes can we make to help lower these statistics?

I don’t have an answer, but let’s talk. Something’s gotta give.

References

Bailey DS. 2006. Burnout harms workers’ physical health through many pathways. Monitory on Psychology. 37(6):11.

Dyrbye LN, Thomas MR, Massie FS, Power DV, Eacker A, Harper W, Durning S, Moutier C, Szydlo DW, Novotny PJ, Sloan JA, Shanafelt TD. 2008. Burnout and Suicidal Ideation among U.S. Medical Students. Ann Intern Med. 149(5):334-341.

Plotnikoff NP, Faith RE, Murgo AJ, Good RA, editors. 2007. Cytokines: Stress and Immunity, Second Edition. Florida: Tylor & Francis Group, LLC.

Offit PA. Jun 2013. Don’t Take Your Vitamins. The New York Times [Internet]. [cited 2014 Nov 30]. Available from: http://www.nytimes.com/2013/06/09/opinion/sunday/dont-take-your-vitamins.html?pagewanted=all.

Rabin RC and Kaiser Health News. Mar 2014. A growing number of primary-care doctors are burning out. How does this affect patients? Washington Post [Internet]. [cited 2014 Nov 30]. Available from: http://www.washingtonpost.com/national/health-science/a-growing-number-of-primary-care-doctors-are-burning-out-how-does-this-affect-patients/2014/03/31/2e8bce24-a951-11e3-b61e-8051b8b52d06_story.html.

Shanafelt TD, Boone S, Tan L, Dyrbye LN, Sotile W, Satele D, West CP, Sloan J, Oreskovich MR. 2012. Burnout and Satisfaction With Work-Life Balance Among US Physicians Relative to the General US Population. Arch Intern Med. 172(18):1377-1385. 

Fact or Fiction: Women Who Room Together, Cycle Together

My roommate and I are polar opposites in many ways: she’s a tall blonde with a gregarious personality; and I’m a petite brunette who may admire J.D. Salinger a bit too much; but late one Tuesday night, we suddenly felt like sisters.

Tired, moody and PMSing, we bundled into the car in our PJs and drove to the local ice cream parlor for a salted caramel cookie crunch cure-all. In stereotypical fashion, we bemoaned the less exciting aspects of womanhood and wondered if we had fallen into sync with each other’s cycles. Naturally, we did a little digging…

The Evidence

For:

In 1971, based on a phenomenon called the Lee-Boot effect, which describes the influence of pheromones on the oestrous (reproductive hormone) cycles of mice, Dr. Martha McClintock surveyed 135 women in a college dorm to see if a similar phenomenon occurred in humans.  She found that women who spent the most time together had closer onset dates for their periods. Follow-up studies showed comparable results.

25 years later, Dr. McClintock conducted another study and found that the sweat from women in the follicular (egg maturation) phase of their cycles led other women to have shorter menstrual cycles; while sweat from women in their ovulatory (egg release) phase, lengthened the menstrual cycles of other women. She continues her work today.

Against:

Critics of the menstrual synchrony theory cite problems with studies like Dr. McClintock’s, including: flawed assumptions, unsound statistical methods, and sampling biases. In a critical review done by Dr. H. Clyde Wilson of the original McClintock study, correcting these “errors” erased the observation of significant levels of menstrual synchrony.

Furthermore, it’s hard to eliminate pure coincidence. Two women’s periods are, in fact, statistically likely to overlap. The average woman has a 28-day cycle, thus the maximum amount of time that two women may be out of phase would be 14 days. Given that information, on average, the onset of the two women’s periods would be seven days apart, and fifty percent of the time they would be even closer. Since a women’s period usually lasts for about five days, an overlap is almost to be expected!

The Verdict

Speculation remains over if, why and how this phenomenon occurs in humans. Nonetheless, some studies suggest that there is a sliding scale of sensitivity to certain pheromones, such as 5alpha-androst-16-en-3alpha-ol, which may affect the presentation of menstrual synchrony.

References

McClintock MK. 1971. Menstrual Synchrony and Suppression. Nature. 291:244-245.

Morofushi M, Shinohara K, Funabashi T, Kimura F. 2000. Positive relationship between menstrual synchrony and ability to smell 5alpha-androst-16-en-3alpha-ol. Chem Senses. 25(4):407-11.

Rudis J. 2008. True or False: Women Who Live Together Tend to Have Synchronized Menstrual Periods [Internet]. Beth Israel Deaconess Medical Center web site. [cited in 2014 Nov 30]. Available from: http://www.bidmc.org/YourHealth/Therapeutic-Centers/Womens-Self-Care.aspx?ChunkID=156991

Wilson HC. 1992. A Critical Review of Menstrual Synchrony Research. Psychoneuroendocrinology. 17(6):565-591.

Shocking...The Brain that Is

In recent years, it has become a common practice to find a machine that will replace the effects of hard work and practice. Many of these can be fond during late-night infomercials, but some lucky few have graced the pages of science literature over the past decade. One such treatment is known as transcranial direct current stimulation (tDCS). As the name implies, the goal of tDCS is to provide a low wattage of electrical impulse to the brain to help improve neuron firing (or slow it if the results are undesired) by changing the electrical environment around the neurons.

For those of you new to the physiology blog, it is important to remember that neuron firing is the propagation of an action potential down the axon of the neuron. This propagation is achieved by voltage-gated ion channels that allow for the environment within the neuron to go from a resting negative electrical environment to a positive one. Without getting into the gritty details, the message will be continued down the axon with a short delay afterward to help reset the chemical environment that helps make this axon firing possible. The idea of tDCS is that you can use electricity (hopefully in small, controlled doses) to improve the way neurons function in the brain. With persistent treatment and stimulation from the external environment the neurons might be tricked into long-term potentiation, known more commonly as learning. Like the Ab Master 3000, the end goal is that you do minimal effort to achieve maximum results. It's like giving your brain a six pack. The benefits touted include improving memory, treating depression, making you more creative, making making mental math easier and improving your reading comprehension and speed.

Now for the sad news. A group of researchers has reviewed the roughly 200 studies confirming the impacts of tDCS and found no significant results are truly confirmed in any of the studies. The disclaimer is that testing the effects of tDCS is very challenging limited only to testing associated impacts like improved blood flow to an area or how muscle contraction improves after stimulation. The results are highly variable and the controls in the studies have been called into question as well. Some in the scientific community wave this discovery of...well nothing significant as merely an inability to measure what they are sure is happening. Others believe it undermines the entire area of treatment by refuting the impacts on physiology. More research reviews are being conducted by the group from The University of Melbourne where the first was published focusing on the cognitive impacts of tDCS. The initial results have been deemed controversial at best. The moral of the story is we can't really say what tDCS does with full confidence.

If you are looking to improve the way your brain works, try practicing the skill in question. If you spent the resources you originally invested into researching and buying a DIY tDCS kit and simply practiced mental math, you would likely see the same improvements in your skills. Neuroscience is growing every day and getting closer to finding the way to grow and improve the human brain, but until then, take those few extra seconds and struggle through the mental math and create long-term potentiation for nothing but your time.


Resources:
http://www.sciencedirect.com/science/article/pii/S0028393214004394
http://www.newscientist.com/article/dn26636-has-the-brainzap-backlash-begun.html#.VHyIXIvF-Sq