Unraveling Science

Answering complex problems and discussing topics in biochemistry, genetics, physiology, laboratory techniques, and more.

How accurate is the show Dexter when he uses a syringe to instantly knock out his victims with a single poke?


Psychopath Blood Splatter Analyst Serial Killer

Psychopath Blood Splatter Analyst Serial Killer

Dexter the psychopath blood splatter analyst is routinely found in situations where he relies on his syringe to almost instantly put people unconscious. Is this even possible? Lets explore.

Dexter uses a synthetic opioid etorphine to put his victims unconscious. It is noted in the show this opioid is used as an animal tranquilizer and licensed to certain individuals. According to a  1982 paper published in the Journal of Zoo Animal Medicine a polar bear was induced using etorphine in roughly 13 minutes. This drug has be proven to induce catatonic states in animals and possibly apnea if overdosed. In the show Dexter always inserts his needle directly into the necks of his victims. Assuming he was able to hit the jugular vein which feeds blood directly into the heart his drug would hit 10 times faster than an intramuscular injection. And would be even faster if injected into the carotid artery which feeds directly into the brain. So although it would induce unconsciousness fast it would not be instant as seen in the show.

Lets also explore the idea Dexter’s technique. The jugular and carotid line both sides of the neck and can be felt under the connective tissue. Dexter would need to insert his need into the blood vessel at perfect angle to penetrate the vessel without exiting the other side of the vessel. In order to ensure he is actually in a vessel he would need back draw blood into the syringe to guarantee he is not injecting intramusclular.

So there you have it. The show is a great show and great entertainment, but is not quite accurate.

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MCAT Question of the Day: 4/30/13 – Cell Biology


Q: Messenger RNA is coded by:

A. Ribosomes

B. Endoplasmic Reticulum

C. DNA in the nucleus

D. Cytoplasm

 

 

 

 

 

Answer (Highlight below for answer)

C

DNA within the nucleus of cells encodes all RNA. Ribosomes decode RNA aiding in protein synthesis and this typically occurs in the cytoplasm. Additionally the endoplasmic reticulum assists in the finished protein products by adding additionally modifications and packaging proteins to stick the the cell membrane or exportation from the cell.

MCAT Question of the Day 4/28/13: Cell Biology


Q: If a cell was placed into a isotonic solution…

A. Water would pass out through the plasma membrane faster than it goes in.

B. Water would pass in through the plasma membrane faster than it goes out.

C. The cell would swell.

D. No unequal rates would be experienced.

 

 

 

 

 

The correct answer is: (Highlight to see answer)

 

D

An isotonic solution has a very similar osmotic pressure to the cell itself thus molecules of water will enter and leave the cell at equal rates. If the question has asked hypertonic solution then the osmotic pressure would be greater outside the cell and water would leave the cell shrinking it. Similarly a hypotonic solution would swell the cell with water because the osmotic pressure would be less outside the cell.

Pros and Cons of Caffeine Consumption


A_small_cup_of_coffee

I would go so far as to say that our Western society is fueled by an eight carbon organic molecule, C8H10N4O2, or 1,3,7-trimethyl-1H-purine-2,6(3H,7H)-dione
3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione, or best known as Caffeine. Caffeine is found in almost all energy drinks, teas, soft drinks, and especially coffee. It is well known that caffeine is a stimulant and can induce both mental and physical improvements for a temporary period. The compound caffeine is a bitter crystalline xanthine alkaloid and is even toxic at higher doses.

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In our fast paced society it is no wonder that  caffeine is the most widely used and commercially available drug. Its stimulant effects can allow users to bypass the sleepiness of an early morning, disregard tiredness for a late night, or just feel alert throughout the day. So its no wonder why many people who work mentally demanding jobs turn to caffeine as an simple aid. Even athletes turn to caffeine to increase their performance. All studies point towards an increased output of an athlete under the effects of caffeine compared to non-users. However, caffeine is not a miracle drug and does carry some significant complications in users.

548px-Main_symptoms_of_Caffeine_overdoseCaffeine primarily affects central nervous system and causes a strong increase in both heart rate. In some users this increase has led to panic attacks and fear of a heart attack. Additionally caffeine is a known trigger of anxiety and has been shown to worsen anxiety and panic disorders. People prone to anxiety respond differently to caffeine and rather than feel energized they may just sense impending doom. Insomnia , headaches, twitching, ringing in the ears, nausea, and dehydration are all known side effects of the caffeine, but for some the extra energy outweighs all side effect.

I know caffeine has always been beneficial to my work output, but I know of people who never touch it and also seem to have all the energy they need. Comment this page and let me know how caffeine effects you, how you use it your advantage, or why you avoid the stuff like the plague.

The Hormone Blues


A friend of mine is currently studying hard for the MCAT exam and decided to mix his musical talent to better remember the body’s hormones. There a few key hormones that are tested on the MCAT such as estrogen, epinephrine, or insulin. Hormones are secreted by tissues known as glands and can act locally around that tissue or can be transported throughout the body for a systemic effect. With out further ado I give you The Hormone Blues.

What are the four basic tissue types?


Groups of cells collectively organize into a structure known as a tissue. The properties tissue is determined by the different cell types that form it and there are generally four types of tissue. Each tissue type has its own subgroups, but the subgroups have similar properties and functions.

1. Muscle Tissue  –  Muscle tissue is assembled by myocytes, or muscle cells, and allows the skeletal system to move using contractile forces. There are three different groups of muscle tissues which differ in their physical properties and their location in the body. Striation is a physical characteristic used to recognize different muscle tissues and typically means the sarcomeres are repeating. The striated muscles visually look distinct because of repeating segments of thick and thin protein filaments. Skeletal muscle is striated muscle and controlled voluntarily. Smooth muscle is located along the walls of the digestive tract, blood vessels, uterus, and urinary bladder. It is nonstriated and involuntary. Cardiac muscle  is located within the heart, it is striated, and involuntary.

2. Nervous Tissue – Nervous tissue are composed of neurons. This tissue has the specialized role of responding to external and internal stimuli by transmitting impulses from one area of the body to another. The tissue can induce a response in distant muscles to contract, glands to secrete, or regulate other body processes. The nervous tissue composes the nervous system. Nervous tissue forms the central nervous system brain and spinal cord as well as the peripheral sensory receptors.

3. Epithelial Tissue  – This tissue type has many subgroups, but for the most part have similar characteristics. Epithelial tissue covers the the external surfaces of the body as different layers of skin. It lines the internal tubes and cavities of the body. Characteristically it has compactly aggregated cells, no blood vessels, and has limited intercellular space.Epithelial cells are also polarized where the top and bottom of the tissue is quite distinct. Additionally the tissue is derived from all three germ layers.

4 Connective Tissue – The last of the four tissue types is like packaging material of the body. Connective tissue supports the other tissues of the body. It is developed from the mesoderm and contains ground substance, fibers, and cells. The ground substance is an amorphous material found between the cells and fibers and acts route of passage of nutrients and waste to and from the cells. The fibers add support and strength to the connective tissue. The cells of connective tissue are typically nonmotile, but some have the ability to wander. Fibroblasts are found most abundantly in connective tissue especially in ligaments and tendons. Additionally free and fixed macrophages uptake foreign material in connective tissue acting as an arm of the innate immune system. Adipocytes or fat cells are large and round cells with a large lipid droplet taking up the majority of their volume.

How is blood pressure measured in small animals?


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How is it that pharmaceutical companies can develop drugs for humans that lower their blood pressure? Drugs like Lipitor, Levacor, Zocor, and other blood pressure reducing drugs were all tested first on animals. After any drug is developed the next step is to determine both its kinetic and dynamic effects on an organism. You may already know that rats are consistently used in research labs, this is because they are an excellent model organism. That is their DNA differs from humans only slightly and many of our proteins are the same.
So we have our new blood pressure reducing drug, but how to test it on our rats? There are a few methods we can use to measure a rats blood pressure changes. A tail cuff will enclose the tail of the rat while it is still awake and restrict blood flow just like the cuff a nurse would use to measure our own blood pressure. This method is a bit inaccurate because a rat doesn’t take to kindly to having its tail squeezed.
Another method is to use a catheter inserted directly into the blood vessel and then use a blood pressure transducer to measure the changes. This method is highly accurate, but comes at a few more risks. The catheterization requires a surgery and risks infection of the animal, especially if their immune system is compromised. Additionally the catheter line can be compromised by blood clots or the animal somehow damaging it. However, the catheter is an still an excellent research tool because the accuracy of the measurements outweighs the risks in many cases.

What is an ELISA assay and why is it performed?


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In this 96 well plate the wells with the darker wells have a greater concentration of a specific protein than lighter wells. Any well with no color can be considered to have none of the specific protein.

Biologists who work with smaller organisms, like bacteria and cell cultures, or larger organisms, like mice and rats, need a way to really know if a specific enzyme or any molecule for that matter is actually there. For instance if we are looking for a protein that may be related to cancer we not only need to know if our organism has this protein, but also a way to quantify how much of the protein is there. Sometimes in biology the enzymes that lead to cancer are required for normal cell activity, but when expressed at greater amounts than normal they can cause serious problems.The ELISA assay is simple test that can fairly accurately predict the both the existence of our protein of interest, but also can measure the quantity of this protein.

Image

(1) The antibody coated to surface of well (2) Protein of interest binding antibody (3) Primary antibody binds the protein of interest (4) Secondary with bound chomophore antibody binds the primary antibody (5) Light from spectrophotometer is absorbed/emitted by the chromophore

ELISA is an acronym for enzyme linked immunosorbent assay, the technique utilizes our understanding of antibodies to bind our protein of interest as an antigen. You can read a bit more about antibodies from my other articles on the immune system, but in this assay they are stuck to a surface. This well plate has 96 wells each coated with an antibody that will bind only a specific antigen. For each ELISA each different protein we want to measure requires a specific plate with a specific antibody.

Lets look at an example where we are quantifying the amount of testosterone in blood plasma. Our blood plasma samples would be added in small amounts to the wells of our ELISA plate and given sufficient time for the antibodies to bind the testosterone hormone. Additionally we may add a solution containing a “detecting antibody”. After allowing the binding to take place our plate can be washed several times to remove all of the extra contents that did not bind. The washing process will flush out everything except our testosterone bound to the antibody on the plate and the detecting antibody also bound to the testosterone molecule. We call this a detecting antibody because it is important in allowing us to measure the quantity of testosterone. The detecting antibody is a primary antibody because it binds the testosterone hormone directly, but after the washing phase we will next add a secondary antibody. The secondary antibody labelled with some fluorphore or chromophore and is secondary because it binds the primary antibody rather than the testosterone hormone. The fluorophore or chromophore on the secondary antibody is what allows the detection of testosterone. By using a spectrophotometer or fluorometer a light of a specific wavelength will be absorbed and the absorbency can be measured. I will explain a bit more about these devices on a separate post, but now our testosterone hormone can be measure in terms of absorbency. Additionally to our well plate we would add several different known concentrations of pure testosterone to several wells as a control to ensure the plate is binding testosterone, but also to compare absorbance values when quantifying our protein concentration from our samples.

ELISA is an important technique in research as we are using new compounds to directly affect the concentrations of specific enzymes or other molecules, but also a key component of clinical biology. ELISA can be used to detect the presences of HIV antibodies of a suspected infected individual. It is used to detect endotoxins of bacterium in certain foods to guarantee the food has not been contaminated with deadly E. coli. Overall ELISA is a remarkably simple, but highly universal technique many biologists rely on everyday.

Why ibuprofen and naproxen sodium are essentially the same?


Typical 200mg tablet of Ibuprofen

I recently argued with a coworker about the differences between ibuprofen, the compound use in drugs like Advil, and naproxen sodium, the active compound in Aleve. I asserted to my coworker the drugs are essentially the exact same, but her unscientific mind could not believe me. So I will explain the biochemical mechanism of these drugs and why they both relieve pain in the same manner.

Pain sensation in our bodies is caused by our cells reacting to damage and responding by synthesizing compounds that alert us of the damage which is our perception of pain. The compound synthesizes are prostaglandins and are always expressed in response to tissue/cell damage. Blocking the generation of prostaglandins is the key element to inhibiting the sensations of pain. The enzyme that generates prostaglandins is the cyclooxegenase-2, or COX-2. There are two isoforms of the COX enzyme though COX-1 and COX-2. So in understanding why naproxen sodium and ibuprofen are the same one must understand they both are nonselective inhibitors of the COX enzymes. That being said both naproxen sodium and ibuprofen effectively block both COX-1 and COX-2. This is why they are essentially the exact same in drug effectiveness despite what some people seem to prefer, Aleve vs. Advil.

However because both drugs are nonselective they can cause problems throughout the body when inhibiting the COX-1 enzyme. The COX-1 enzyme is important in the production of platelets required for coagulation of blood. This is why people will use both ibuprofen and naproxen sodium as an anticoagulant. Using either drug over a period of time will result in blood thinning and the ability to clot blood effectively. Red blood cells (RBCs) generate platelets using the COX-1 enzyme, but cannot regenerate extras of the enzyme because the nucleus is lost in all RBCs. For this reason both naproxen sodium and ibuprofen will inhibit COX-1 in RBCs permanently until the cell dies and is replaced.

Overall the ibuprofen and naproxen sodium are effectively the same. Here you can find a few links to research papers that will back my reasoning. Trends from different studies go back and forth on which drug was prefered by the patients tested. Nonetheless either drug will get the job done.

http://www.ncbi.nlm.nih.gov/pubmed/7555617

http://www.ncbi.nlm.nih.gov/pubmed/6344227

http://www.ncbi.nlm.nih.gov/pubmed/6181256

Poisonous Plants That Will Kill You – Strophanthus and Ouabain


   Its been a while since my last post, but I will try to get back to work making interesting posts. Today I am introducing a new series to my blog, Poisonous Plants that will kill you, that I hope to post weekly or biweekly. So for todays plant I will introduce the genus Strophanthus and its deadly toxin Ouabain.

For a short history this plant traditionally grows in Southern Africa and produces a cardiac glycoside toxin, Ouabain. African tribes have known of the poison for a long time and would tip their arrows in it.

What I find most interesting and I hope my readers do as well is the biochemistry of this toxin and just how deadly it is. I mentioned ouabain is a cardiac glycoside which means it interacts with a cardiac protein. Ouabain is a deadly poison because it binds the sodium potassium pump on the surface of cardiac cells preventing contraction of the heart muscle. The Na+/K+ pump is an active transport enzyme that moves sodium to the outside of the cell in exchange for potassium. The enzyme like all enzymes perform their mechanism by binding the desired molecule, the enzyme then converts to its transition state before releasing the product and returning to its first state.

Enzyme + Substrate —> Transition State Enzyme with Substrate Bound –>  Enzyme + Product

So in the case of Ouabain the cardiac glycoside binds the transition state of the enzyme and inhibits the enzyme of returning to its normal state and releasing the product.

You may be asking why is this sodium potassium pump critical for the contraction of cardiac cells. The sodium concentration outside the cell is consistently higher than inside and moving sodium outside the cell requires ATP. The Na+/K+ pump doesn’t just bind singles of these elements but actually moves 3 sodiums out in exchange for 2 potassiums. The net effect of moving mass amounts of sodium out of the cell at this ration results in depolarization of the cell because the difference in charge from the less potassium. Another pump, a Ca/Na pump moves calcium out of the cell in exchange for the sodium and is responsible for stopping the contraction. High levels of calcium are critical to the contraction. Calcium from the sarcoplasmic reticulum is stored until depolarization and it can be released to be available to bind troponin for contraction. Thus inhibiting the sodium potassium ATPase with ouabain results in a cardiac cell unable to stop contraction due to the calcium levels remaining too high.

Cardiac glycosides such as ouabain have played a critical role in our understanding of the Na+/K+ pump and its role in the cell. Researchers have used ouabain in-vitro studies to understand this process, but the drug also has clinical potential. Conjestive heart failure occurs when the heart fails to pump sufficient supply of blood to the body. Ouabain and other cardiac glycosides have shown to be effective at low concentrations to improve the contractions of the heart.