Saturday, November 15, 2014

Blog Update!

Great news, folks! Cosmodynamics is moving to Medium.

Check it out here, and don't forget to subscribe for more doses of sciencey goodness from the worlds of physics, astronomy, biology, and medicine. Cheers!

Epidemiology at Home: On Keeping Our Infectious Diseases in Perspective

'Tis the season for medical sensationalism in the American news media. First there was the Enterovirus, or EV-D68. Soon thereafter, we witnessed the arrival of Ebola on American soil. Thanks to Ebola's notoriously high mortality rate and the devastation the virus has wrought in Africa, well-meaning public officials here in the U.S. took up a call to arms for their own citizens... and panicked. Despite the facts - first, that Ebola is very difficult to catch, requiring direct and intimate contact with the blood or body fluids of an infected an outwardly symptomatic person; and second, that medical infrastructure in an industrialized nation such as ours make it easier to successfully treat and heal an individual who does catch the virus - the general public here in America is still on edge. And, I will argue, understandably so. Ebola is a serious disease, as is EV-D68 in children with respiratory problems. But "fair and balanced" or not, mainstream news outlets are typically very good at only two things: getting clicks and generating panic.

The problem is not widespread fear over deadly infectious diseases. Instead, the problem is public perception of relative risk. Big names like Ebola and EV-D68 get a lot of press, while more low-profile, everyday diseases like Influenza end up with considerably less screen time. Meanwhile, every year our old friend Flu is responsible for millions of severe illnesses and hundreds of thousands of deaths across the globe - orders of magnitude more than Ebola and Enterovirus combined. And here's the kicker: Flu is preventable.

Flu differs from Ebola in a variety of ways, including its ease of transmission and its capacity to mutate quickly from season to season. Infected persons can transmit the disease to others up to a day or so before they begin showing symptoms. The Flu is transmitted by droplets of moisture that are expelled into the air when an infected person talks, laughs, coughs, or sneezes. Others can also pick up the disease by touching surfaces where these droplets have landed and then failing to wash their hands before wiping their nose, rubbing their eyes, or otherwise touching their face. Once inside the body, the Flu virus spreads to the respiratory tract and causes widespread inflammation, leading to the characteristic signs and symptoms within a matter of days. Usually, healthy individuals begin to feel better within a week or two; however, as with most infectious diseases, the very young, the very old, and the chronically sick or immunocompromised are the most at risk for complications from the illness. At its worst, Flu can cause exacerbation of underlying heart or lung conditions, severe pneumonia, or respiratory failure. In children, a high fever often accompanies infection with Flu and, if unchecked, can cause brief febrile seizures. Even those with an uncomplicated case of Flu can expect to feel chilly, fatigued, congested, achey, and feverish for a few days. Unfortunately, recovering from the virus once offers little protection against future Flu seasons.

Given the severity of this year's outbreak of both EV-D68 in the United States and Ebola in Africa, many concerned citizens are clamoring for the creation of protective vaccines against these diseases. Yet many of these same concerned citizens decline the Flu shot for themselves and their children, usually with one of the following explanations: "It will make me sick," "I got that one year and then I got the Flu anyway," or "Nah, it's just the Flu. I'll take my chances." Each of these statements is misguided. The Flu shot is made up of an inactivated virus, so it is incapable of making anyone sick. Even the Flu spray, which is a nasal mist version of the immunization that contains a drastically weakened version of the virus, is specifically designed to convey immunity without being strong enough to cause infection. While it is possible to contract a rare strain of the Flu even after getting the Flu shot or spray, this is uncommon. It is much more likely for an individual to catch a severe cold and mistake it for the Flu or catch the Flu itself during the vaccine's two-week immunity-building period. Lastly, the Flu is a severe illness, especially for those who are already at risk for getting sick.

So, if you are feeling troubled about the state of public health in the world today, I have one recommendation: Get your Flu shot. Although it may not completely allay your fears, checking this box off your to-do list will categorically decrease your chances of catching a potentially deadly infectious disease within the next few months. Not everyone in the world has access to that kind of protection, so use it to your advantage! Then, stay away from the blood of people who are infected with Ebola, and you will (probably) be 2 for 2.

Friday, November 14, 2014

2014 A Space Odyssey: Rosetta, Philae, and the Great #CometLanding

It is official. Humankind has successfully landed a man-made probe on a comet! On November 12th, the spacecraft Rosetta released its sister probe, a 100-kg payload named Philae, to a choreographed free-fall toward the surface of a rotating comet called 67P/Churyumov-Gerasimenko. The success of this launch is a testament to both the power of modern technology and the amazing scope of human ingenuity.

One of Philae's first images of the surface of its new home, comet 67P/Churyumov-Gerasimenko

Let's recap. Rosetta and Philae spent the last decade hurtling toward a relatively tiny, moving target at a distance of almost 600 million kilometers, course-correcting four times thanks to the gravitational influence of both Earth and Mars, successfully rendezvousing with said comet, carrying out the prescribed launch sequence, free-falling for a nail-biting 7+ hours, and finally, actually touching down on the surface in the exact spot that had been planned. Philae's initial touchdown was unexpectedly brief, however, due to the failure of its harpoons to fire and anchor it to the surface. The probe bounced three times before submitting to the feeble gravitational influence of 67P; by this time, the comet had rotated in such a way that Philae ended up resting in the shadow of a cliff, kilometers away from its planned destination. Even with a successful nudge toward a brighter area, the probe's batteries will probably lack sufficient sunlight to maintain their charge and will likely run out of juice sometime on Saturday, November 15th. Battery failure could spell the end for Philae, but all is not lost! Scientists at the European Space Agency (ESA), the organization behind the mission itself, estimate that Rosetta's landing probe will have collected and transmitted 80-90% of its data by the time its batteries are completely drained.

So what kind of data is Philae collecting, and how will the Rosetta mission help us to understand our place in the Universe? First, Philae's ten scientific instruments will tell us more about the chemical composition of 67P at varying depths, as well as its temperature, density, and magnetic properties. Complex imaging equipment has already begun returning photographs of an alien surface humankind has never seen before. Secondly, the Rosetta spacecraft will continue to orbit the comet even after Philae ceases its transmission. Over the next year, the spacecraft will accompany 67P as it approaches perihelion, or the point in its orbit when it is closest to the sun. As the comet swings through the inner solar system, Rosetta will monitor and record its increased surface activity in order to better understand what happens when comets are heated by the sun's thermal energy. Together, both Rosetta and Philae will assist scientists in building a more accurate and comprehensive picture of the physics and chemistry of comets. These insights may go on to inform theories about the origin of water and/or life in our solar system, which often feature comets as central players.

Despite their prominent role in human legend, comets have actually remained fairly mysterious to astronomers throughout history; however, thanks to modern science, Philae and Rosetta are set to revolutionize our understanding of both these icy bodies and their potentially illuminating role regarding the evolution of our planet and wider solar system. Whether Philae will be brought to life again at some sunny time in the future or whether it will soon go to sleep forever, it has done a superb job epitomizing the human drive toward adventure and discovery.

Three cheers for Philae, and for these few truly monumental days in scientific history.

Thursday, September 11, 2014

Review of Epigenetic Influences Offers New Perspectives on Health and Illness

Human lives are governed by vanishingly small threads of chemical instructions, bundled into orderly parcels and locked deep within the heart of our cells. These filaments are DNA, a kind of molecular textbook that uses short sequences called genes to tell the body what proteins to make and how to use them. Genes give rise to all sorts of attributes, including what we look like, our personalities, and our health. But these genes are not set in stone. Epigenetics is a branch of science dedicated to understanding the ways that our genes are influenced by factors other than DNA, such as drugs, foods, behaviors, and life experiences.

An individual's so-called "epigenome" exerts vast and enduring control throughout his or her life, from conception to death and even beyond. Emerging research suggests that epigenetic effects also play a powerful role in the development of disease, revealing increasingly refined targets for future scientific and biomedical studies. This week, a trio of scientists from Howard University released an extensive review that details these effects. Their paper, published in Frontiers in Cell and Developmental Biology, offers a convincing argument for increased epigenetic research and better public understanding. Ultimately, they contend, mastery of epigenetics will lead to improved well-being and longer, healthier lives.

First, a bit of background. If DNA is the textbook, promoter regions are the subject headings that tell its readers, proteins called transcription factors, where to begin. Transcription factors encourage a copying enzyme called RNA polymerase to re-write every word of the DNA molecule on a new template, a strand of material called messenger RNA. This new molecule is not actually identical in sequence to the parent DNA strand; instead, it is made up of opposite and complementary "words," or codons. A sequence of related codons on a strand of DNA is called a gene.

Each codon is comprised of three small bags of chemicals called nucleotides. Nucleotides are extremely picky characters and will only bind in concrete twosomes: C with G, and A with T or U. The sequence of nucleotides created by RNA polymerase depends on the order of codons presented by the parent strand of DNA. That is, if the DNA textbook reads CTG, RNA polymerase will re-write this codon as GAC. The strand of messenger RNA that results from all this copying will ultimately create a blueprint of the organism's genome from which cellular factories can build proteins, the workhorses of the body.

Epigenetic influences can greatly impact this copying process. By tagging key segments of DNA with chemical markers, the epigenome can enhance, prevent, or modulate local transcription, effectively controlling gene expression. This process can occur directly, in the case of a drug that interacts biochemically with a gene, or indirectly, when a signal cascade triggered by the environment leads to the release of molecules that prompt an epigenetic response. Through complex processes called methylation, histone modification, and RNA-mediated silencing, the epigenome can exert a surprisingly powerful force on the body, starting at the very beginning of life.

Early in development, a rapid round of demethylation and remethylation "resets" the fetal genome and erases potentially harmful changes that have accumulated in parental DNA. Even so, a mother's environment during pregnancy readily impacts the genome of her child. For instance, women whose diets vary with the seasons develop an epigenome that regulates their nutritional requirements in accordance with the environment. Those who are pregnant during especially lean months tend to have low birth weight babies who remain smaller throughout life than those who were born of more plentiful times. Maternal stress during pregnancy also has epigenetic effects on the fetus, ultimately increasing the child's susceptibility to neurological disease and heightening his or her stress response. These kinds of diet and stress-mediated markers can become imprinted upon the child's DNA, later going on to evade the genetic reboot and influence future generations.

An infant's epigenome is exquisitely sensitive to the presence or absence of bonding and attachment behaviors soon after birth. Baby mice who are routinely groomed by their mothers exhibit a much healthier levels of stress and anxiety later in life than those who were ignored. Like human children, mice who are left to fend for themselves as babies appear to develop key epigenetic signatures in genes that control cortisol receptors, those areas of the brain that regulate the fight-or-flight response.  These same changes occur in children who witness violence or experience abuse, predisposing them to developing mood disorders as adults.

Epigenetic modifications also result from our own individual choices, both positive and negative. For instance, research suggests that healthy decisions regarding diet and exercise actually prevent disease on a molecular level. The high levels of folic acid and antioxidants found in fresh fruits and vegetables work to reduce DNA damage by cleaning up regions that have been inappropriately silenced or activated. Alternative medicine modalities such as acupuncture have also been lauded for their beneficial genetic effect on cardiac health. Similarly, exercise prompts activation of genes that increase metabolism and strengthen muscles, even in otherwise sedentary individuals.

Drugs, alcohol, and environmental toxins also induce epigenetic changes, but they are far less favorable. Instead, these substances often modify DNA in ways that encourage proliferation of rogue tumor cells or alter the genes that control neurotransmitter release. Some studies also indicate that altered circadian rhythms could be driving epigenetic modifications that underlie the current epidemic of obesity and type 2 diabetes. Unsurprisingly, many diseases have been shown to result from unsavory changes in the epigenome, such as Alzheimer's, arthritis, heart disease, and cancer.

In recent years, biologists have uncovered a surprising and significant link between our nuclear microcosm and the external environment. For example, intensely stressful events such as famine and abuse imprint genes that will go on to affect future descendants; nutrients found in herbs and spices protect the DNA from harmful mutations; and cancer cells derive potency from the silencing of their peers' tumor suppressor genes. Each of these discoveries implicates the study of epigenetics as a central theme in human health and well-being, placing it at the heart of the burgeoning field of personalized medicine. A more comprehensive understanding of our plastic genome should allow doctors and individuals alike to make better decisions about the prevention and treatment of disease. Ultimately epigenetics seems to reveal that - for better or for worse - much of our health is truly in our own hands.

Tuesday, July 1, 2014

Please Vaccinate Your Children. Sincerely, Your Friendly Neighborhood RN


Look, I get it. I am one of the yuppiest hippie wannabes I know. I buy organic produce. I meticulously inspect food labels for the presence of preservatives or synthetic texturizers. I know what buzzwords to look out for in my shampoo. I frequent the Environmental Working Group's website to be sure that my cosmetics are safe. I have DIYed my own window cleaner, makeup remover and face cream. I try to only take OTC drugs when I'm feeling really, really down and out. I am one of those people who wants a doula and a midwife by my side when it comes time to have a baby. I do my best to inspect every last thing that comes near my body in the vain hope that I can out-do the mass industrialization of nutrition and personal care. My husband has born the brunt of it; I can only imagine what a madwoman I am going to turn into when we have children. So yes, I understand where you are coming from. In any other circumstance, I would be wary of agreeing to inject myself or anyone else I knew with some mystery chemical compound simply because that's what society is telling me to do.

BUT. I am also a nurse, and so I curb my neuroses when it comes to basic public health and safety. And so I'm going to say this very, very carefully: vaccines are, without question, one of the greatest, most miraculous public health accomplishments in the history of humankind. I mean it. They are up there with sewage treatment facilities, seat belts and antibiotics. Before we routinely administered today's safe, reliable vaccines, measles killed around 400 people each year. Tetanus killed around 500. Diptheria, pertussis, polio, and rubella each independently killed thousands. Keep in mind that many of those deaths were infants and young kids. And today, hundreds of thousands of men, women and children are spared these diseases, not because of better sanitation practices or better overall medical care, but because they have been immunized against them. But an increasing number of individuals - the very young, the very sick, and the very un-vaccinated - are not afforded the same protection, simply because of misinformation, mistrust and/or ignorance.

Tuesday, January 7, 2014

On the necessity of birth control in space.

The other night, John and I were browsing nerdy videos on YouTube when we happened upon one clip that discussed whether pregnancy, birth and development were possible in outer space. Given my background in astrophysics and my current pursuit of a career in OB nursing, John quickly became convinced that we had found my life's work... SPACE BABIES.

"Space Babies" Kia Sorento 2013 Super Bowl Ad

This probably isn't the start of a new and glorious career (thank you anyway, honey), but it did get me wondering about the logistics and limitations of the question. Let's say that some nice couple on the International Space Station decides that they want to have a child before their contract is up (secretly, of course, because apparently sex is expressly forbidden aboard the ISS). Would it be possible for them to conceive, and later have, a normal, healthy child?

It seems that the short answer is "no." According to research led by Joe Tash, a biologist at the University of Kansas, the high-energy radiation and so-called microgravity (10-3 G) that astronauts are subjected to during long spaceflights can have serious negative effects on their reproductive systems - namely, plummeting sperm counts and shriveling eggs. Similar concerns about the detrimental effects of space-level radiation are well-publicized. In fact, in 2010, China announced that it would require all of its female astronauts to be married with children in an effort to minimize the impact of the reproductive problems women might experience upon their return.

On the up side, a 2005 study out of the University of Texas showed that many female astronauts easily became pregnant after coming back to Earth; however, the same study also revealed a higher-than expected miscarriage rate among those pregnancies. Radiation could be to blame for these losses, but an equally plausible explanation could involve the effect of microgravity on human sex cells. Research published in 2009 in the Public Library of Science ONE showed that despite successful fertilization, many mouse embryos that were exposed to microgravity conditions stopped dividing before they reached crucial stages of development. Furthermore, Joe Tash's research also revealed severe dysfunction in the reproductive organs of female mice after about two weeks of flight aboard the space shuttle Discovery. The effect in these mice was so extensive that many of their follicular cells (the cells that produce eggs) had died and their ovaries had started to shut down.

Eek. But let's say that this daring couple is also very lucky, and they do successfully conceive a child. (We'll go ahead and skip over the logistics and precariousness of actually taking a pregnancy test in the first place.) Research suggests that while some animals, such as salamanders and fish, appear to gestate normally in microgravity environments, the outlook for mammals is decidedly more complicated. For one, some studies have suggested that microgravity can lead to fetal malformations in utero, including failure of the neural tube (the primitive brain and spinal cord) to close like it is supposed to. For another, mammals that were gestated in microgravity environments appear to have an altered vestibular response, the sense that allows a person to achieve a sense of balance and direction. Like all of our other senses, it requires stimulation to develop properly. Babies born in a microgravity environment would never learn to prefer one direction over another, leading to a compromised vestibular sense and big problems once they landed on Earth. Studies with rats have shown that a proper vestibular response can be learned over time; however, it is unclear whether that would hold true for human infants, especially if those babies spent months or even years in microgravity conditions.

And when we consider that the human body requires weight-bearing in order to stay strong, we come to another problem. Even adult astronauts have to remain vigilant about their exercise routine in order to avoid muscle atrophy and bone loss that can easily occur during long spaceflights. To a very small, rapidly developing body, these threats could be catastrophic. Additionally, the fluid shifts that commonly occur in astronauts living in microgravity environments could be far more dangerous for infants and small children, since their bodies contain more water than those of adults. Not to mention the increased risk for electrolyte abnormalities, changes in blood vessels, compromised cardiac functioning, and altered circadian rhythms that microgravity creates.

So. Overall, I think it's safe to say that conceiving, carrying, birthing, growing, or even thinking about space babies is probably not a good idea. NASA would do well to continue funding research into the effects of spaceflight on both male and female sex organs, but until we can manipulate gravity and block space-level radiation, reproduction in space just doesn't appear to be something our species is meant to experience.