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May 8, 2012

Posted by srstone in Biology, Evolution, Genetics, Health, Medicine, Science Education.
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Viruses: Friend or Foe?

What is invisible to the naked eye, can affect the Earth’s climate, has a tiny shell, and can causes cancer?  Viruses are considered non-living, but play a major role in our bodies and environment.  In fact, viruses kill half of the bacteria in the ocean every day.  To get an idea of how much bacteria that is, a teaspoon of water contains approximately a billion bacteria.  Recent estimates show there are 1031 viruses on this earth.  That reads, 10 billion trillion, trillion.  Although viruses are smaller than what the unaided eye is capable of viewing, if all viruses were stacked end to end, they would be lined up for about 100 million light years.

How Viruses Work

 

Viruses are constantly on the attack from the outside of our body desperately trying to get in, but 4 trillion viruses also reside inside our body.  While some viruses are trying to find a host cell and cause harm, many viruses are necessary for a healthy life.  Some of the viruses inside of us can protect us from detrimental bacteria, but can also help balance the population of bacteria vital to our health.  A similar phenomenon occurs in the ocean.  Without viruses consuming half of the bacteria day in and day out, the levels of bacteria in the ecosystem could hamper the living of certain species.  Also, bacteria contain carbon and lots of nutrients.  With the viruses consuming the bacteria, there is a constant recycling throughout the ocean.  There is a hypothesis that because of all the carbon that’s coming out, it could be affecting the Earth’s climate.  Any of the carbon that is sent back to the atmosphere is going to trap heat (greenhouse effect).  It may be an extreme thought, but these tiny, non-living viruses are partially responsible for the weather.

Bacteriophages: the lifeless killers

Viruses that attack and dispose of bacteria are known as bacteriophagesFelix d’Herelle discovered the extraordinary conclusion that viruses can kill bacteria through treating a dish of bacteria with fluid from patients with dysentery!  He actually began a business selling viruses that could cure bacterial infections.  Hypothetically, there are viruses that exist in nature that can kill the most severe bacterial infections, but it’s a matter of discovering the right viruses.  Each species of bacteria has a series of bacteriophages that can eliminate it.

Antibiotics and Viruses: An evolutionary arms race

Before antibiotics were discovered in the 1930s, a method called phage therapywas used to combat infections.  However, once these antibiotic “magic pills” were discovered, phage therapy stood in the distance.  The chemicals were reliable and scientists knew how to make them.  However, with the current widening spread of antibiotic resistance caused by bacteria developing resistance to modern medicine’s most well-used antibiotics, it’s beginning to look like phage therapy wouldn’t be a terrible idea.  One main argument phage therapy new found interest: antibiotics can’t evolve, while viruses can.  Scientists have reached the point where viruses can be engineered and genes can be strategically placed to enhance their effectiveness.  This genetic and evolutionary tinkering could allow scientists to develop viruses to strategically kill various bacteria that might be antibiotic resistant.

Genetic Engineering of Viruses

 

Viruses: Directors of Their Own Fate?

In the wake of the recent deadly avian flu virus, critics have questioned whether the spreading from mammal to mammal could have occurred on its own.  A study completed at MSU by Justin Meyer was started with the thought that it would be a wild goose chase.  Meyer wondered if lambda phages could evolve another way a new way to enter its host.

lambda was used to infect the gut bacterium E. coli.  It is harmless to humans.  The most common means for lambda to get into a cell is by attaching to its outer membrane.  The genes and proteins contained by the lambda are then injected into the microbe.  Meyer used E. coli that didn’t make the molecules necessary for the virus to grab onto.  This meant that the only viruses that would survive were ones that mutated to use a different surface molecule.  Shockingly, within 15 days, Meyer’s experiment showed that viruses were using a new channel in E. coli known as OmpF.

Meyer re-conducted the experiment with 96 lines of the virus and E. coli.  Of those 96, 24 of the lines began to use OmpF as the pathway into the host.  Because of the repeating phenomenon, the genomes of the evolved viruses were sequenced, finding that four mutations were required for the viruses to thrive.  All four were required, not a single one, or even three out of the four.  Meyer estimated the chance of all four mutations arising at once was nearly impossible: one in a thousand, trillion, trillion. However, the lambda viruses evolved to contain all four mutations in a couple weeks on a regular basis.

As incredible as this experiment is, it is somewhat frightening.  Meyer showed how easily viruses can evolve completely new traits, which can lead to new diseases.  This is exactly the reason why when treating a sickness with antibiotics, the patient MUST finish taking the dosage until it is gone, otherwise the virus can come back even stronger.

 

 

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 Something in the Water: Tracing the Cholera Outbreak in Haiti April 13, 2012

Posted by srstone in Biology, Environment/Conservation, Evolution, Genetics, Health, Medicine, Policy, Science & Culture.
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 Something in the Water

Cholera Under the Microscope

When we go to the sink to get a glass of water from the sink, we trust that what the water is comprised of is safe for us to drink.  Most of us don’t give a thought as to what could be in it.  This is one of the luxuries of living in a first world country.  However, those in third world countries, such as Haiti, are not so fortunate.  Shortly after the earthquake in Haiti in 2010, a cholera outbreak occurred.  When an outbreak like this occurs, the goal is to not only check the spread of the disease among Haitians, but to prevent the bacteria from swapping DNA with other cholera strains in the country to form a more dangerous bug much harder to treat.

Antibiotic-resistant Cholera: Mechanisms explored

Bacteria reproduce asexually by a process called binary fission.  Binary fission causes two genetically identical bacterial cells to be produced.  If this was the only method bacteria had to procreate, treating a disease with antibiotics would be simple.  Antibiotics aim to either kill bacteria directly or hamper their ability to grow and reproduce.  This can be done by crippling the production of the bacterial cell wall and inhibiting protein, DNA, or RNA synthesis. 

However, when we put our bodies on the attack with the use of antibiotics, bacteria respond by playing their side with different defensive mechanisms.  Some of these mechanisms include changing the permeability of their membranes.  For example, bacteria can decrease the number of channels available for the antibiotics to enter the cell.  Another mechanism works by changing the actual physical structure of the antibiotic once it enters the cell so that the drugs can’t bind the way they were designed to in order to have an effect.  Although both of these mechanisms prevent antibiotics from carrying out their job, bacterial recombination is the most common form of developing antibacterial resistance.  When this happens, bacteria gain genetic variation by swapping DNA with other bacteria.  This allows the bacteria to acquire resistance to the drug.  A plasmid, which is a circular piece of DNA, can encode resistance to multiple antibiotics. Thus if one bacterial cell in the environment has evolved resistance to an antibiotic, it can easily share that information with other surrounding bacteria leading to an epidemic of widespread antibacterial resistance.   A transposon, known as a “jumping gene”, can jump ship from DNA to DNA molecule.  The transposon then becomes part of the plasmid.

Where did it come from?

Cholera, which had never been seen before in Haiti prior to the earthquake, had the advantage.  Nations offering their help focused on the earthquake recovery while cholera entered Haiti under the radar.  Reducing the fatality rate from cholera has been a success; however the response was slow to fully develop.  The most likely story is that cholera spawned from a Nepalese volunteer at the Minustah base.  Understandably, no one wanted to take responsibility for bringing an epidemic to a country that already needed all the help they can get. 

To resolve the “blame-game”, Danish and American scientists collaborated to determine where the cholera came from.  Haiti’s cholera strain and Nepal’s cholera strain of the bacteria were examined using the most comprehensive type of analysis: whole-genome sequence typing.  Virtually identical, the Nepalese were forced to accept blame.  Another method, pulse-field gel electrophoresis was also used as evidence.  Scientists found that cholera erupted in Nepal in July 2010, but was under control the following month in August.  Unfortunately, this was the same month that Nepalese soldiers left for a recovery mission in Haiti.        

Resolutions?

Through the application of genetics, the cholera strain has been identified.  Unfortunately, this doesn’t solve Haiti’s problems.  Only 12% of the population has access to piped, treated water.  The rest find their water in rivers and wells.  These are the same rivers that contain feces and that Haitians wash their clothes in.  Vaccinations and supportive care will aid in the conquering of cholera, but until safe water is more readily accessible, the country needs to be prepared for round two.

A Typical Haitian Laundry Room

Effect of environmental toxins on GATC methylation in E. coli May 3, 2011

Posted by ljsteele in Biology, Chemistry, Ecology, Environment/Conservation, Evolution, Genetics, Health, Marian University curriculum, Physiology.
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With the end of the semester drawing near it is becoming that time again when the results are piling in from research you have been working on all semester. As we speak, the final data collection and analysis is taking place in biochemistry, a team of student researchers are exploring of environmental toxins of DNA methylation  in the bacterium E. coli. 

The Bacterial Genome

Bacteria exist throughout the world and can survive in almost any climate . Bacteria are unicellular and can consist in a wide range of environments such as a pond all the way to soil.  One unique attribute of the bacterial genome is that it contains adenine methylation , opposed to mammalian organisms which contain cytosine methylation at GpC islands.  Adenine methylation is when a methyl group becomes attached to the adenine nucleotide on the DNA. When a methyl group is donated from SAM to form a covalent attachment, it is made on the adenine which can cause steric hindrance of transcription factors and differential effects of DNA binding proteins, which can contribute to a change in gene expression.  In previous studies  it has been shown when E. coli is exposed to different carbon sources (ie glycerol or glucose).  Some areas of the genome become demethylated.  In the bacteria E. coli almost every adenine (A) in the GATC sequence is methylated.  To block the methyation at the GATC sequence, a protein must be present to inhibit the DAM methyltransferase from depositing a methyl group on the adenine.

What does Methylation do?

Adenine methylation has many roles in bacteria. Methylation can effect gene expression, cell cycle, virulence, and how proteins interact with the DNA. For the research we are performing, we are concerned with what effect the environment has on changing adenine methylation on the GATC repeats. There are about 20,000 GATC repeats in the E. coli genome and under normal log growth conditions almost every single repeat is methylated. It has been found that when bacterial cells are in a log growth phase there are 6-10 sites which are not methylated. These nonmethylated sites lie up and down stream of promoters of different genes. The lack of methylation may allow DNA binding proteins to modulate their function to allow a functional change in gene expression.

Pollutants and the Genome

In the study we are performing we wanted to see how three classes of chemicals pollutants commonly found in the Midwest affect adenine methylation at the GATC site. We choose three pollutants to represent chemicals that fit into the families of common water pollutants, which are heavy metals, chlorinated compounds and nitrogen rich compounds.Gel Electrophoresis

The above families of compounds will be compared to samples collected from different areas around the campus of Marian University, Indianapolis, IN. Supplements will be added to all the samples to generate a rich liquid media that will facilitate bacterial growth.  With 6 different test groups and 2 controls we are going to seek to determine if any of our known compounds or a compound present in our environmental sample has an effect on the methylation.  The determination of methylation can be done by using restriction enzyme digest with endonuclease selecting specifically for the nonmethylated site.  The enzyme we have chosen was MBO and AVI.  When all the genomic DNA from the bacteria is extracted and digested, then it will be ran on a gel to be imaged to determine if the bands of digested DNA differ depending on the chemicals present during growth.  This is a time efficient way to examine if any changes in methylation levels have occurred.

What Does It All Mean?

For conclusion, the relevance of this study includes a few things.  This study will provide evidence to show if environmental toxins have an effect on bacterial DAM methylation. One role bacteria play in an ecosystem is influencing the flow of nutrients which support plant and algae growth. The results of our proposed study may display that toxins have an effect on methylation patterns which could lead to an increase the mutation rate of the bacteria genome itself.   Destructive mutations may decrease bacterial populations leading to a disruption in the ecosystems nutrient flow, hence disruptions in plant and algae growth with effect additional aquatic and terrestrial organisms.

Mystical “Catnip” May 3, 2011

Posted by mhostetler099 in Behavior, Biology, Chemistry, Health, Physiology.
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So what is it about “catnip” that makes cats crazy, mosquitoes fly away and at the same time has seemingly no effect on human beings?  In actuality, the better question is what are the distinguishing factors allow different organisms to interpret “catnip’s” chemical signal differently or not at all.

The 6th Sense (the vomeronasal organ in cats)

It is well documented that all mammals posses 5 senses (sight, taste, touch, smell, hearing); BUT could mammals have a 6th sense?! Some scientists would say YES and pinpoint this sense to be related to the mysterious vomeronasal organ located above the roof of the mouth.  This sensory organ is attributed to sensing chemical signals from other organisms and the environment known as pheromones.  The vomeronasal organ is present in most mammals and is considered a chemoreceptor organ which exists as a separate entity than the nasal cavity.  Chemoreceptors detect chemical signals from the organism’s environment and transduce a physiological response accordingly. Studies indicate that nepetalactone (the chemical produced by “catnip”) is responsible for eliciting a psychosexual response in cats by mimicking a sex pheromone and interacting with the feline vomeronasal organ.  Although human beings and felines are both mammals, they react to the chemical in “catnip” much differently than one another.  “Catnip” elicits no response in human beings and a rather strong response in felines.  The distinction between these responses can most likely be attributed to a physiological difference in the feline and human sensory system.

The Vomeronasal Organ in Humans

The function of the vomeronasal organ in human beings is actually quite controversial.  Studies on human embryos have indicated that the vomeronasal organ does correspond to the vomeronasal organ in cats and other mammals.  Although the vomeronasal organ is common in both feline and human species, the organ in humans was thought by scientist to be vestigial (or no longer functioning).  The vestigality of the vomeronasal organ in human beings may explain why humans do not react to chemicals in “catnip” however this is an unlikely explanation because studies have shown human beings can react to pheromones.  Another explanation to the differing reactions could potentially be attributed to the physiological differences in the organs themselves (show left). 

 So Why are Mosquitoes Repelled?

So why are mosquitoes seemingly repelled by some essential oils extracted from different plants and herbs (including “catnip”)?  This question is a little more difficult to answer directly because little is known about insect sensory system.  Studies have shown that mosquitoes are more attracted to people with high concentrations of steroids and cholesterol on the surface of the skin.  Mosquitoes are attracted and repelled by certain pheromones.  More than likely, the chemical nepetalactone in “catnip” is able to mimic a pheromone that triggers a chemical signal causing the insect to become repelled (acting as an insecticide).

It is truly amazing that the same chemical can signal different responses in different organisms.  The responses to chemical signals in the organism’s environment are evolutionarily beneficial; whether it be to attract a mate or flee from impending danger.  According to a news report conducted by NPR the CDC is working on natural repellant consisting of extract from cedar tree.  This substance is completely environmentally friendly and actually acts as an insecticide.  It is able to kill the mosquitoes by blocking receptors on their nerve cells (absent in human beings).  Although the chemical found in “catnip” is not known to be an insecticide, the similarity between natural extracts (from “catnip” and cedar tree) may certainly explain insects natural repulsion from them.

Crazy for “Catnip” March 14, 2011

Posted by mhostetler099 in Behavior, Biology, Chemistry, Fun, Health, Uncategorized.
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“Catnip,” a feline favorite, is a perennial herb in the mint family

Nepeta cataria, more commonly known as “Catnip” is a perennial herb that belongs to the mint family.  This herb packs a powerful punch to cats by provoking a state of euphoria usually lasting several minutes (video).   Many times herbs are utilized for medicinal purposes , but “catnip” obviously doesn’t affect human beings in the same way that it does cats.  What is it about “catnip” that provokes a euphoric response in cats but not in human beings?

The chemical component responsible for the effects of catnip

Studies suggests that the chemical nepetalactone found in “catnip” is primarily responsible for triggering the response in cats.  Nepetalactone evokes a psychosexual response in both male and female cats by mimicking a sex pheromone found in cat urine.

Bugs aren’t so crazy for “catnip”

The chemical nepetalactone may attract felines, but does quite the opposite to some insects.  Researchers at Iowa State University found that the chemical nepetalactone is a successful repellent of mosquitoes, flies, and cockroaches.  Particularly, the research team at Iowa State found that a solution of catnip extract is comparable in effectiveness to a ten times more concentrated solution of DEET.  Research in finding alternatives to repellents or pesticides, such as DEET, is very important because chemicals contained in most pesticides pose a serious threat to human health and the environment.  Unfortunately, the essential oils in “catnip” are extremely volatile and have a potent, but short lived repelling effect.  Further research in reducing its volatility is essential before such repellents can be used by the general public.

Catnip’s properties are multifunctional

Interestingly, researchers at the Max-Planck Society found that birds that used different types herbal plants in their nests produced offspring that were less prone to infestation of mites.  This study indicates that other herbs may have the same insect-repelling power as “catnip” and that organisms other than humans are using this characteristic to their benefit.


In the future, the active ingredient, nepetalactone, may be found in the bottle of repellent you spray on yourself or the pesticide you sprinkle on your plants.  You can be sure that the product you are using is much safer than the products of old, but if you have cats you must beware!  Such products will still provoke the same euphoric response caused by “catnip” sold in pet stores.


Cramming: A Student’s Best Friend? March 4, 2011

Posted by ljsteele in Behavior, Biology, Chemistry, Health, Medicine, Science & Culture, Uncategorized.
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The night flies by…

As a senior undergraduate student, slowly over the past four years I have realized the importance of cramming before a test. Simply put, by this stage in my academic career, it has become routine to stay up all night before a test to study.  In classes where there are multiple choice tests, it appears to be easier to stay up all night cramming, as is the belief that if you at least can recognize the question, ruling out the different choices for the answer becomes quite simple.  It has been shown that over a third of students cram the night before a test.

Equal Justice?

However, although many students utilize the practice of cramming, whether or not it helps students is up for debate. There are different levels of cramming, and each appear to cause different results when it comes to grades and GPA.  The issue that is starting to be seen is that although cramming may help in terms of short term memory, the retention of that information weeks after the course ends seems to be up in the air.  Of course, when cramming is being utilized, it only makes sense that the information storage would be contained in the frontal lobe of the brain, while long term memory, which would be associated with studying that has taken place over numerous days or weeks, would be stored over multiple parts of the brain.

Green highlighted area represents the frontal lobe of the brain

Many different universities have brought to light the health implications that one may bring upon him or herself when cramming. But, it is also shown that certain periods of acute stress are positive for the human body, which cramming would appear to fall under the category of acute stress. During acute stress, the body increases its fight or flight response (epinephrine and norepinephrine), shuts down digestion, reproductive systems, and boosts metabolism. Vasoconstriction and vasodilation also take place, therefore pumping blood into certain areas of the body and brain that during a normal day’s activities may not get stimulated very often.  Especially during the fight or flight response, one becomes more attentive, which would seem to help with say, studying for a huge test.

Are there more effects than just retaining information?

Although cramming may not be ideal for certain people, research needs to continue in terms of stress and cramming, and even learning styles.  Certain people are exposed to more stress than others, so possibly stress levels are compromised, leading to a decreased ability to study and cram the night before a test.  Students continue to cram because results are obtained on tests and finals.  Quite possibly cramming could do more than just get a student a good grade on a test-it could also help to train the body for different stress activities that otherwise may not be achieved.


Healing a “Broken” Heart March 4, 2011

Posted by Kyle in Biology, Chemistry, Health, Medicine, Physiology.
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Irreparable Harm

The majority of those reading this have probably experienced some sort of injury in their lifetime.  Injuries such as cuts and broken bones will soon heal with proper care, but there are certain tissues that if damaged, cannot repair themselves. Heart tissue and brain tissue are two examples that come to mind. This may be the case for most of us adult humans, but new research out of The University of Texas Southwestern Medical Center at Dallas is pointing out that some newborn mammals have the ability to heal completely when it comes to heart damage. The only problem is, at some point along the line, as we age, the heart loses this ability to heal itself. Still, this is a very important discovery for a society that suffers greatly from heart disease, which kills thousands of Americans every year.

Studying a Broken Heart

Researchers found that in newborn mice, when sections of heart were removed, the heart had completely healed within three weeks. The hearts then functioned as normal with no signs of damage. Understanding how this works and why the heart stops doing it after a certain amount of time is now the next step for researchers. Unlike when you tear a hamstring, damage to cardiac tissue after a heart attack doesn’t just heal with time. So for those who suffer from heart problems, a discovery like this brings them one step closer to a healthy heart in the future.

Of Mice & Men

Obviously mice, which help us a lot more than most people realize, and humans are a little different from each other, but seeing results like this in another mammal is still promising. If nothing else, it is definitely a huge step in the right direction for researchers looking to cut down on the number of heart related deaths. For now though, it is important for people to remember that they only have one heart, and taking care of it should be a priority.


Taking a Radioactive Drag: Polonium 210 and Cigarettes March 3, 2011

Posted by tsublett in Chemistry, Health, Medicine, Physiology, Policy.
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Radioactive Smoke: A Dangerous Isotope Lurks in Cigarettes

The Unknown and Known Dangers of Smoking

Many of us know the dangers of smoking. We see many friends and loved ones diagnosed with cancer and know of many who die from it each year. We have seen the warning labels on cigarette packages, but what is actually in that smoke? Research says, it’s polonium-210, a radioactive isotope found in fertilizers. The problem is, tobacco companies knew about this, a while ago. According to a 2011 article in Scientific American, “The tobacco industry has known about polonium in cigarettes for nearly 50 years.” Facts like these are disconcerting on many levels.

A Tobacco Plant

Ways We Are Exposed to Polonium 210

How exactly this isotope gets into the tobacco leaf is not entirely known, but it is thought to be a “daughter isotope of uranium 238 found in fertilizers. When the fertilizer is spread on the soil, it begins to decay into either an airborne isotope, such as radon 222, or into lead 210 in the soil. Both of these products enter through the roots or into the leaves and eventually decay into polonium 210. The leaves are then processed normally and eventually end up in cigarettes.

The History of Polonium 210 Detection

Now, then, there seems to be a problem. See, polonium 210 was detected first in the 1960s. This should be a BIG problem, because we are now considering its dangers even though it has been known about  for 50+ years! Through a series of papers published during the 1960s, namely a paper published in 1964 by Radford and Hunt, scientists demonstrated how polonium 210 can enter the soil.  Subsequently in a paper published in 1974, by John B. Little and William O’Toole, proved that smokers can develop “hot-spots” on their lungs where polonium 210 accumulates. The hot spots can cause mutations due to alpha decay . The problem is, tobacco farmers and cigarette manufacturers are not removing this isotope. The good news is… they may start doing so soon.

How much polonium do we get when we smoke?

Here is an excerpt from a New York Times article:

A fraction of a trillionth of a curie (a unit of radiation named for polonium’s discoverers, Marie and Pierre Curie) may not sound like much, but remember that we’re talking about a powerful radionuclide disgorging alpha particles — the most dangerous kind when it comes to lung cancer — at a much higher rate even than the plutonium used in the bomb dropped on Nagasaki. Polonium 210 has a half life of about 138 days, making it thousands of times more radioactive than the nuclear fuels used in early atomic bombs.

We should also recall that people smoke a lot of cigarettes — about 5.7 trillion worldwide every year, enough to make a continuous chain from the earth to the sun and back, with enough left over for a few side-trips to Mars. If .04 picocuries of polonium are inhaled with every cigarette, about a quarter of a curie of one of the world’s most radioactive poisons is inhaled along with the tar, nicotine and cyanide of all the world’s cigarettes smoked each year. Pack-and-a-half smokers are dosed to the tune of about 300 chest X-rays.

 

Is there any relief?

Maybe we should stop smoking, it’s likely the best approach. If you can’t quite kick the habit, the FDA may help. Recently the FDA has taken over the regulation of cigarettes in the wake of the Family Smoking and Tobacco Control Act passed in 2009. With the FDA’s help, the exact content of polonium 210 in cigarettes may soon be published. On a side note, one quick fix may come in tobacco leaf preparation. Simply washing the leaves after harvest may eliminate a large portion of the polonium 210 found in the air.

 

The Largest Preventable Cause of Death in the World.

It seems like a radioactive isotope found in smoke is just one of many carcinogens that continue to contribute to tobacco being the largest preventable cause of death in the world. According to Scientific American:

The World Heath Organization has made clear that smoking is the most avoidable cause of death. It estimates that 1.3 million people die of lung cancer worldwide every year, 90 percent because of smoking. If polonium has been reduced through methods known to the industry, many thousands of those deaths could have been avoided. The industry, many thousands of those deaths could have been avoided. The industry’s lawyers made the conscious choice not to act on the results of their own scientists’ investigations. But it is the customers who have had to live with-and die from- that decision.

So, cigarettes are bad, but how bad they may be for us is still up in the air. Perhaps we can make them a little less dangerous in the future by removing these dangerous isotopes. Hopefully, with the FDA regulating cigarettes, this dangerous vice will soon be put to rest.

Mysterious Melatonin December 18, 2010

Posted by Kyle in Biology, Chemistry, Health, Medicine, Neuroscience, Nutrition, Physiology.
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I am sure everyone has already heard of a little compound known as melatonin. Melatonin is a hormone that can be found in many different organisms including plants, although most people know melatonin for its actions in mammals. In humans, melatonin is produced in the brain by the pineal gland. Circulating melatonin levels have been found to be high at night and low during the day, which is consistent with research that has shown that light suppresses melatonin. Because melatonin plays a role in controlling the circadian rhythm, it has received much interest for its use as a treatment for various sleep disorders. Because melatonin is a hormone, supplementing melatonin can present some issues.

Many people have used melatonin supplements to help them sleep at night. If you take a trip to your local drug store you are likely to find melatonin on the shelf. The first time I came across melatonin supplements I couldn’t help but think about the potential negative aspects to selling melatonin over the counter, unregulated. As many of you know, the human body likes to maintain homeostasis. When this delicate balance is interrupted, the body will react to return to homeostasis. I started to wonder what happens when someone takes melatonin supplements. The first thing that comes to mind is a decrease in the amount of melatonin receptors or a decrease in the production of melatonin itself, or both. I also wondered about possible side effects of increasing melatonin levels. As we have seen with many other hormones, multiple pathways and mechanisms can be influenced by a single hormone. So someone taking melatonin to help them sleep could inadvertently throw off other pathways, like those involved in reproduction for example.

Melatonin has been shown protect against reactive oxygen species, which can wreak havoc inside cells. This could potentially be an obvious benefit to taking melatonin supplements, especially if it helps an individual sleep at night. While sifting through the literature, I was unable to find any studies specifically looking at the negative effects of taking melatonin supplements, if any. But just because it isn’t proven that something is bad, doesn’t mean the potential for bad isn’t there. Also, other countries have taken action to stop over the counter sale of melatonin. Of course, there is also the question, do melatonin supplements even work?  How much of the melatonin present in a melatonin pill is denatured by stomach acids or excreted in urine before it even has an effect?

I am skeptical of melatonin supplements, if you haven’t noticed yet. To each his own, but I don’t think I will be purchasing or taking any melatonin supplements in the near future.  Good luck to everyone on their upcoming finals. Make sure to get plenty of sleep, although if your to-do list looks like mine, that won’t be happening.

Stress and the GI Tract December 17, 2010

Posted by ljsteele in Behavior, Biology, Chemistry, Ecology, Environment/Conservation, Health, Neuroscience.
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The mechanics of stress and the gut.

Stress is shown to have a huge effect on the body, whether or not it is experienced as an acute or chronic stress.  A major topic of interest is what effects stress has on the gastrointestinal tract in organisms.  According to a multi-part scientific paper entitled “Stress and the Gastrointestinal Tract”, there are many different stressors that can be examined within a variety of organisms.  Examples of the stressors explored include food deprivation, fearful sounds, weather changes, and water avoidance ( an acute stressors explored in lab organisms such as mice, rats, and guinea pigs).  It has also been shown that acute stressors in humans, such as pain exposure, anger, fear, and intense exercise can cause gastrointestinal shut down.

From the stressors listed above, research has explored how stress influences gastro muscles to slow contraction,  thus inhibiting the processing of food.  An interesting reaction to this slowing of peristaltic movement is the fact that many organisms lose control of their colon, showing defecation in response to certain stimuli such as fear and water avoidance.  Corticotropin releasing hormone, also known as CRH  (or CRF, as identified in the aforementioned paper), is released from the hypothalamus, and blocks the effects of the vagas nerve, while also traveling through the solar plexus, and attaching to receptors in the stomach.

Stomach ulcer

Once bound, this hormone has been shown to inhibit gastro movement, and thus preventing emptying of the stomach. The difference between the stomach and the colon is that the stomach requires contraction of the muscles to push food through, whereas the colon requires contraction to keep bowel movements inside the body.  With the effect of CRH binding to the receptors, relaxation in gastrointestinal muscles occur, which is why the release of the colon sphincter results.  However, the results explored here were in response  to short term stressors.  The effects of long-term stressors have yet to be studied.

Stress and Ulcers

What does this research mean to you?  Well, the results we glean from research like this offer powerful implications for human medicine and today’s society.  Many people not only experience acute stress, but chronic stress as well.   Short term affects of acute stress include accelerated of heartbeat and an increase in metabolism, but it is only natural to ponder the long term effects of chronic stress.    We can extrapolate from the results of  acute stress that it would make sense that we, as humans, would not want these effects to be long lasting.  Major problems would arise with the decrease of gastro movement.  Problems manifest from a build up of bile and stomach acids in the stomach.  Since gut motility is decreased when stressed, less movement would mean that more bile, which is highly acidic, would sit in the stomach longer and could lead to stomach or intestinal ulcers.

Sympathetic Nervous System

Chronic stress can also lead to a decrease in the immune system of the organism as well as a decrease in the second messenger systems within the body.  An example of this effect on a second messenger system is the attachment of CRH to CRH-receptors in the solar plexus.  The binding of these receptors causes the effect of the decrease in gastro movement.

How much stress is too much stress?

Lastly, with chronic stress and chronic stimulation of the CRH/CRF system, we might see a scenario in that the more that these receptors are activated, the more desensatized they can become. This could cause problems for people and their response to stress.  If the are “desensitized” this may mean that these people have a problem when trying to   properly responding to an acute stressors when needed.