The Complexity of Pain Sensation and Management

When it comes to protecting the body, pain perception and sensation is crucial to our physical welfare and care. Unlike some receptors which are limited, such as those stimulate by light or chemicals, pain specific receptors known as nociceptors are found everywhere in the body and are constantly at work to warn of possible injury. Of course, being so important, the transduction mechanism is incredibly complex, relying not only on signals generated by the harmful stimulus on the nociceptor, but also on the supportive and regulator roles of surrounding cells.

In the simplest sense, pain is perceived when a painful stimulus acts upon a nociceptor and causes the cell membrane of the receptor to depolarize and generate a signal. This signal is then transmitted to the central nervous system to be interpreted through the sequential depolarizing and hyperpolarizing of the cell membrane as it travels down the nerve. Besides this general picture, nociceptive activity can be augmented by nociceptive sensitizing agents released by surround cells, such as cells damaged during an injury, (Argoff 2011). By releasing pro-inflammatory factors such as bradykinin, prostaglandin E2, nerve growth factor, and others, these mediators affect the membrane potential of the nocieptors and lower the threshold needed for activation (Argoff 2011). Studies show that glial cells, once thought of as only supporting cells, also have the ability to increase nerve excitability through the release of nociceptive sensitizing agents and thus also play a role in the initiation and maintenance of enhanced pain states (Argoff 2011).

As studies continue and greater understanding is gained, health professions are discovering more efficient ways to treat their patients and provide management practices. Recently, it has been found that, single analgesic therapies may be limited in their ability to comprehensively target certain mechanism and be effective in chronic pain management (Argoff 2011). Because of the complexity and variety of physiological mechanism involved, single-agent therapies are not optimal because they address a limited number of transmission and modulatory pathways (Argoff 2011). In comparison, multi-drug analgesic approaches take advantage of complementary mechanism to reduce pain and thus decrease the dosage needed and negative side affects (Argoff 2011). In a study involving post-surgery shoulder pain, it was found that combining ropivacain, morphine, and ketorolac reduced the incidence of nausea, lowered postoperative pain at rest and with movement, and reduced post-operative morphine consumption (Argoff 2011).

Still what are some difficulties that arise with the use multiple drugs? Why is this not implemented more when it comes to pain management?

Argoff, Charles. (2011). Review: Mechanisms of pain transmission and pharmacologic management. Current Medical Research and Opinion, 27, 2019-2031.

Spider Silk

Although spiders are inevitably known for their capacity to spindle a silk web to catch prey, they apparently can release silk from their feet as well in order to maintain a grip on slippery surfaces. The spiders that are able to use this mechanism are tarantulas, specially the Chilean rose tarantula.

Biologist Claire Rind and her colleagues have studied spiders at Newcastle University and their most recent discovery, silk from feet, has left arachnologists from all over astounded that spiders can release silk from other ligaments of the body, not just the abdominal spinnerets. Tarantulas are simply too heavy to just rely on sticky foot hairs to keep their grip when they are climbing as other spiders do.

In order for tarantulas to release the silk from their feet, their body has to be vertical. Rind and her colleagues experimented with the spiders by observing their climbing behavior on slippery surfaces. The tarantula that was being studied was placed in a glass box lined with microscope slides. Then, the box was shaken around in order to ensure the spider to lose its grip. The spider was slipping on the glass but then maintained its grip and was able to hang on. The only part to touch the microscope slide was the feet of the Chilean rose because the slides had silk footprints that were observed under the microscope. To ensure that this phenomenon was correct, Rind also evaluated the molten exoskeleton where silk traces were identified. The spinnerets in the feet looked like nozzles among the setae.

Rind plans to continue her research and eventually discover if any other spider species are capable of secreting silk from their feet just as the Chilean rose does. She also hopes to distinguish if any other ligaments of the spider can use the same mechanism as the feet and the abdominal spinneret.

Berlin, J. Spider spigots. National Geographic. November 2011, Vol 220 Issue 5, page 25.

The Chocolate Exercise Plan

An animal study conducted by Nogueira et al. (2011) began investigating the use of (-)epicatechin in the mimicking of exercise physiology. Epicatechin is one of the main flavanoids present in cocoa, which has the highest content in dark chocolate.

When exercise occurs in mammals, muscle aerobic capacity is increased. The resulting physiological changes are an increase in mitochondrial volume and increase in capillarity. Other recent studies have shown that increased mitochondrial volume may help reduce the effects of aging on muscles (Nogueira et al., 2011). Thus, because exercise is believed to have such a beneficial effect on people's health, the use of substances that produce similar physiological effects are being highly researched.

As mentioned, the consumption of (-)epicatechin is believed to produce similar effects. But the isomers of (-)epicatechin , (+)epicatechin, (-)catechin, and (+)catechin, are not believed to produce these effects, which limits the research to this natural flavanoid of cocoa. The main evidence that led researchers to believe that (-)epicatechin may mimic exercise is that, in low doses, it produces small amounts of nitric oxide that may play a role in biogenesis of mitochondria and also has vasodilation effects.

Because the use of human subjects and the use of exercise as an independent variable is very difficult to produce a study on, an animal model was used for the current in the study. Middle age mice were put into 1 of 4 conditions: 1)Water only (control) 2) Water w/exercise 3)(-)epicatechin 4) (-)epicatechin w/exercise. The fourth condition, (-)epicatechin w/exercise was used so that the effects of (-)epicatechin could be measured in addition to exercise. The trial, which lasted 15 days, examined 4 factors of exercise:

-Overall exercise performance

-Muscle fatigue

-Muscle capillarity

-Mitochondrial biogenesis in the heart and hindlimb muscles.

(The exercise condition that mice in group 2 & 4 underwent was a treadmill for 30 mins 5x/ week.)

Once the 15 days was over, the mice were anesthetized and killed and the specific muscles were dissected. From this, a variety of tests and scans were run on the muscles in order to measure the metabolic activity and physiological changes.

While the results of study showed no significant differences overall, there we are few interesting details that deserve to be noted. In the hindlimb muscles, there was a large difference in the capillarity, both in size and density. Also, the difference between the water and (-)epicatechin group in terms of mitochondrial density was shown to be significant.

The use of (-)epicatechin treatment improved also treadmill performance and delayed the onset of muscle fatigue (Nogueira et al., 2011).

The use of (-)epicatechin alone was shown to increase certain proteins that are integral in the mitochondrial complexes, an effect that can be observed in exercise alone. The current study, as it was the first of its kind, suggests further study of (-)epicatechin and exercise effects, but also possibly combing the two in order to have have a synergistic effect in the body.

So here is question time:

1. Although this study did not show significant effects and differences (statistically), changes and improvements were still observed. Can we possibly use (-)epicatechin to enhance our exercise plan? Or is it enough alone?

2. What do you think about the idea of "exercise mimetic" (using (-)epicatechin to mimic exercise instead of actually doing it)?

Works Cited:

Nogueira, Leonardo., Ramirez-Sanchez., Israel, Perkins., Guy A., Murphy, Anne., Taub, Pam R., Ceballos, Guillermo., Villarreal, Francisco J., Hogan, Michael C., Malek, Moh H. (2011)

(–)-Epicatechin enhances fatigue resistance and oxidative capacity in mouse muscle

The Journal of Physiology, 589(18), 469-7793

The Pupillary Response

After learning about the way the eyes react to light by either constricting or dilating and their and their consecutive nervous system stimulation, I wondered what the mechanism of action was that made the pupils un-reactive to light (“blown pupils”) resulting from head injury. Traumatic brain injuries (TBIs) affect more than 1.4 million Americans annually (Adoni & McNett, 2007). EMTs, nurses and doctors perform a battery of neurological tests when a patient presents with a possible head injury, including pupillary examinations. This exam is especially important because it is easy to perform, non-invasive and can be done whether or not the patient is conscious or under sedation. Three components are taken into consideration, pupil size (normally between 2 and 5 mm), shape (round, irregular or oval) and reactivity to light (brisk, sluggish or non-reactive). The physiologic basis of the pupillary response, as we know, is controlled by smooth muscle of both parasympathetic and sympathetic control and is innervated by three cranial nerves (III, IV, VI). When an abnormality is detected during a pupillary exam and it is determined that it was not a pre-existing problem, it is often indicative of increasing inter-cranial pressure (ICP) due to progression of a hematoma/hemorrhage or cerebral edema. However there are clinical factors, such as drugs or infection that can contribute as well.

When answering the question of whether it is the failure to send impulses either to the eye, away from the eye or compression/damage to the entire nerve, it actually proves difficult to give a solid answer, as there are many causes of different abnormalities. This study observed abnormal pupils in four different categories; unequal pupils, constricted pupils, dilated pupils, and equal pupils with abnormal response. In the cases where the abnormality in the affected eye is dilation with abnormal reactivity, the cause was either a defect in the efferent pathway, compression of cranial nerve III, loss of parasympathetic nerve supply to the sphincter muscle in the iris or in the worst cases, brain death. Complete bilateral dilation with no response to light (“blown pupils”), called Anoxia Mydriasis, is found when transtentorial herniation is evident (Adoni & McNett, 2007) where brain tissue of the midbrain is displaced by edema or hemorrhage into the tentorial notch, putting pressure on the brain stem (ACEP, 2009). In the case that the affected pupil was constricted, the usual cause was disruption in sympathetic innervation due to lesion in the brainstem or damage to the hypothalamus, direct orbital trauma, opiate or narcotic use or viral infection. So as physicians, the pupillary response will be a very important and useful tool in assessing neurological function. But as to the level of difficulty of analyzing the results, don’t be fooled by the simplicity of the test.

Adoni, A. McNett, M. “The Pupillary Response in Traumatic Brain Injury”. The Journal of Trauma Nursing. October-December 2007. Vol. 14, Number 4. Page 190-197. Web. October 28^th 2011.

American College of Emergency Physicians. Critical Care Transport. American Academy of Orthopaedic Surgeons. 2009. Pg 1007-1015

tentorial notch. (n.d.). Merriam-Webster's Medical Dictionary. Retrieved October 29, 2011, from Dictionary.com website: http://dictionary.reference.com/browse/tentorial notch

Carrot juice and it's positive effects on cardiovascular health

According to Recent polls, approximately 864,000 Americans die each year from cardiovascular disease, making up 35% of all deaths in the United States. Obesity elevates the risk for contracting heart disease because of diets rich in fat and cholesterol, which are two factors that majorly contribute to this upward trend in diagnosis. A step in the right direction in the prevention of heart disease is an increase in the consumption of fruits and vegetables. A frequently consumed vegetable, the carrot, is high in fiber, carotenoids, vitamin C and E and phenolic, all essential nutrients needed in our diets. Increased phenolic compounds in the diet parallel a decreased risk of vascular diseases, inhibiting LDL oxidization and total ADL cholesterol. The juice from carrots, containing the most concentration of nutrients, has the positive effect of reducing inflammation and increasing levels of plasma antioxidants.
A study done at Texas A & M University-Kingsville took 8 males and 9 females with elevated plasma cholesterol and triglycerides and asked them to drink 16 oz. of fresh carrot juice for 3 months. A blood sample was taken before and after the 90 study. The results of this study did not change the subjects weight or BMI but did lower systolic pressure by 5 percent and had also showed an unchanged diastolic, showing a decrease in blood pressure. The fasting plasma chemistry marked a significant increase in antioxidant levels and a decrease in malondialdehyde production. An interesting note in this study was that the male and female subjects both started the study with different levels of malondialdehyde in their blood (men being greater number) and by the end of the 90 day’s of carrot juice consumption, the levels in both genders were the same.
This study concluded that there is an association between vegetable intact and a decreased risk of cardiovascular disease in that there is a lowering of blood pressure by carrot juices increase in vasodilation. Because the plasma levels of cholesterol and triglycerides were unchanged, it is evident that both additional dietary and lifestyle changes are required in reducing the risk for cardiovascular disease, but also that an extra bit of veggies a day does go a long way!

Andrew S Potter, Shahrzad Foroudi, Alexis Stamatikos, Bhimanagouda S Patil, Farzad Deyhim Nutrition Journal 2011, 10:96 (24 September 2011)

1 Person 2 types of DNA?

Recently I was watching a crime investigation show and they arrested one man for murder because of blood DNA found at the crime scene. He was later released because though the DNA was his, he wasn’t there, he had donated bone marrow earlier in life and the victim was the recipient hence why the accused’s DNA was at the scene. This was a surprising thought and I decided to look into it, thinking about it it made sense, but I wasn’t sure. I found that this is indeed true, since bone marrow is the site for blood cell synthesis white blood cells from the donor bone marrow will have the donor DNA. This type of blood is called chimerism, since like the mythical creature there are 2 different DNA’s in one body. In an investigation done by Ginsburg et. al. they found that the cells from the host and donor can be found in the donor blood even between siblings in 95% of transplant cases¹. The ones who didn’t exhibit any chimerism are believed to have rejected the transplanted bone marrow since functioning marrow should be putting out its own blood cells with its DNA. In the study they found one person who was very severely immune compromised was found to have DNA T-cells exclusively from purely donor origin². As the person get sicker their own cells are not producing sufficient amounts of white blood cells so more are from the donor marrow. Clinically looking at chimerism can be one way to test how well the recipient is accepting the donated bone marrow. Such diseases include “chronic graft-versus-host disease (GVHD), nonrelapse mortality (NRM), relapse, and overall mortality.”³ These diseases are significant risks to people who have had bone marrow transplants so being able to test for them will help predict if they are doing well and then allow them to be treated if they are not. People at risk for these diseases are ones who have had more serious illnesses before receiving the transplant, these people typically have greater than 95% of their white blood cells coming from the donor marrow.⁴ So it would seem that looking at chimerism would help predict the disease resulting from bone marrow transplant, and while it worked in the trials, in a clinical setting it proved less than useful. Even though chimerism lacks a practical clinical use right now, it is an interesting idea to be researching. Also, if you donate bone marrow your DNA will be in 2 places at once!

Citation:

^1,2 D Ginsburg, J H Antin, B R Smith, S H Orkin and J M Rappeport. Origin of cell populations after bone marrow transplantation. Analysis using DNA sequence polymorphisms.The Journal of Clinical Investigation. 1985;75(2):596–603. doi:10.1172/JCI111736.

^3,4Mossalam, G. Kamel, A. Storer, B. Martin, P. Prognostic Utility of Routine Chimerism Testing at 2 to 6 Months after Allogeneic Hematopoietic Cell Transplantation. Biology of Blood and Marrow Transplantation.2009; 15(3):352-359. doi:10.1016/j.bbmt.2008.12.496

GET FIT!!!

Getting Fit “not fat”, Even if It Kills You

Over the past decade, CrossFit has spread across the country and become the next raging fad, culminating in the most recently televised competition on ESPN. From toddlers to adults, CrossFit has become a cult-like obsession with gyms popping up all across the country. For those new to CrossFit, this regime combines resistance weight training with aerobic conditioning. Controversially, CrossFit has surfaced in the New York Times discussing the possible dangers involved when relatively inexperienced athletes participate in these physically stressful workouts. In the article, “Getting Fit Even if It Kills You”, the author discusses Greg Classman’s near death experience during his first CrossFit workout. After finishing his workout, he drove home in extreme pain, later to be diagnosed as rhabdomyolysis. This condition results from rapid muscular cell death, whose contents are then rapidly dumped into the bloodstream and causes kidney toxicity. Many critics speak about other health risks due to injury from strenuous exercise where speed is emphasized over proper form and technique. Despite these dangers, many different groups of people have been flocking to these types of workouts from financial analysts, former Olympians, to scientists. Although there are apparent risks with these workouts as if with most physical exercise, the US public needs cult-like fads such as “Cross-fitting” to combat many rising health epidemics. For example, the overwhelming majority (66%) of the US population are either overweight or obese and over a third of population do not participate in leisure exercise (36%) according to a US consensus conducted between 2007-2008. These new trends in fitness where small factions of people aim to push themselves to their physical limit seems to be a necessary balance for an increasing inactive population. Even without proper technique, most of these CrossFit routines require small weights (

Downs A, Ashton J. Vigorous Physical Activity, Sports Participation, and Athletic Identity: Implications for Mental and Physical Health in College Students. Journal of Sport Behavior [serial online]. September 2011;34(3):228-249. Available from: SPORTDiscus with Full Text, Ipswich, MA. Accessed October 17, 2011.

Cooperman, Stephanie. “Getting Fit, Even if It Kills You”. Nytimes.com. New York Times, 22^nd Dec. 2005. Web. 23^rd October 2011.

U.S. Census Bureau, Statistical Abstract of the United States: 2012 (131st Edition). Health and Nutrition: Health Risk Factors. Washington, DC, 2011; .

Anti-depressants

A roommate of mine had a difficult time her junior year. She started to lose her appetite, had difficulty focusing, would seclude herself from her friends, and seemed to be emotionally withdrawing herself. After a few discussions with her, we discussed how depression ran in her family, and the symptoms that she was showing seemed to be similar to those of depression.

It was suggested to her that she should go to some therapy sessions to help her with this “depressive state.” She claimed that she did not believe in anti-depressants and their effects, and I secretly had a lack of faith in these drug as well. My roommate attended therapy sessions, was diagnosed as having depression, and was put on anti-depressants. Surprisingly, after a few weeks on this new medication, my roommate began to return to her normal happy-go-lucky self.

Her and I began a quest to learn more about what depression is and how anti-depressants work. We learned that anti-depressants work in ways to alter brain neurochemical systems. Antidepressants focus on affecting the neurochemicals such as serotonin, nonrepinephrine, and dopamine (because it is believed that depression may be due to an imbalance of these neurochemicals). Some antidepressants work directly with the chemicals, and others with the chemicals receptors.

Over 15 million people in the United States are struggling with depression, so clearly the development of antidepressant drugs was necessary. While genetics plays a big role, the environment may also cause a person to develop depression. The article “Clavulanic acid increases dopamine release in neuronal cells through a mechanism involving enhanced vesicle trafficking” is a great example for mechanism of how anti-depressants work. From the study the results showed that clavulanic acid increases dopamine release in PC12 and SH-SY5Y cells without having an effect on the dopamine synthesis in an individual. Clavulanic acid could be used in CNS disorders such as depression (it works with Munc18-1 and Rab4 for vesicle trafficking process, and it is blood-brain barrier permeable). A question that I have is are there ways that a person can prevent depression without reaching to anti-depressants and therapy (such as my roommate)? Or are there individuals where antidepressants are necessary? In physiological terms, is there a way a person can get these imbalanced chemicals in the brain to balance on their own?

Article found from: http://www.sciencedirect.com.dml.regis.edu/science/article/pii/S0304394011013176

DEHP (di-2-ethylhexyl phthalate) and its effects in human reproductive system:

Over the past ten years, there have been different studies that showed that the endocrine disruptor, DEHP might lead to unfavorable reproductive and developmental effects (Swan, 2008). Research has been done to determine the relationship between exposure to DEHP and their metabolites with a decline in male reproductive capacity. The studied also found that endocrine disruptors such as DEHP and mEPH increased the risk of prostate and testicular cancer. Epidemiology studies found a relationship between DEHP exposure and the increase risk of endometriosis, oocyte incompetence, ovarian malfunction, and cancer in females (Swan, et al. 2005). Recent measure the effects of DEHP exposure in early developmental stages. The results indicate that there is a relationship between DEHP and alterations during sex differentiation (Swan, et al 2005; Meeker et al. 2009).

Other recent studies suggest that it is not the amount of exposure that produces increased side effects, but rather the time of exposure. Therefore, recent research is trying to asses if there is a relationship between the time of exposure and the effects of DEHP. The current research by Swan (2008) focuses on early exposure of DEHP in humans. This new area of investigation is very recent and significant however, the outcomes remain unclear. For that reason, early exposure to DEHP should be carefully analyzed and more studies are needed to demonstrate that DEHP is a potent endocrine disruptor that affects the human reproductive system during early development. The findings of Swan (2008) helped to push laws in congress to ban some phthalate metabolites from children’s toys. The research also found a positive correlation of the high number of cases of hypospadias and un-descended testicles in newborn males.

Phthalates are ubiquitous and are widely distributed in the environment. Do you think the Government should create a law, requesting plastic manufacturers to provide information about amount of DHEP present in their products? Or Should the Government increase funding to promote more research regarding the long term effect of phthalates in humans (by measuring blood and urine test DHEP concentrations or by measuring the anogenital distance in newborns?

References:

Meeker, John D., Sathyanarayana, Sheela. Swan, Shanna H.2009.Phthalates and other additives in plastics: human exposure and associated health outcomes. Phil. Trans. R. Soc. B. 364, 2097-2113. doi:10.1098/rstb.2008.0268

Swan .S., Main .K., Liu .F., Stewart S., Kruse. R., Calafat A. et al. 2005. Decrease in anogenital distance among male infants with prenatal phthalate exposure. Environ Health Perspect 113,1056-61.

Shanna H. 2008. Environmental phthalate exposure in relation to reproductive outcomes and other health end points in humans. Environmental Research. 108(2): 177-184.

Neurons--how they encode memories

Related to our current lecture material, researchers have been working on figuring out how our brain does what it does...memorize. Essentially, once neurons synapse, those synapses need to be "strengthened" in order for a concept or idea to be implanted in our memory bank. Activating a neuron (by any sort of stimulus) actually causes the degradation of microRNA's, which therefore enable particular mRNA's to be translated. These newly translated proteins play a part in "strengthening" synapses with other neurons, which ultimately results in the generation of a memory.

http://www.ia.ucsb.edu/pa/display.aspx?pkey=2149

(i found the actual pubmed article if anyone is interested, but its quite complex)

Decoding which proteins are necessary to build stronger synapses, or knowing the specific mechanism by which neurons actually degrade the microRNA's would be monumental towards the treatment of diseases such as Alzheimers or Autism, or even the regeneration of brain function after a traumatic brain injury. This could also create super-brains, and people could have a much greater capacity to learn. Also, i never thought we would be able to explain the concept of thinking, and how our brain actually accomplishes that...but i guess i could be wrong..

Transition of bipedal locomotion in human evolution

The anatomy of the modern human feet enables us to walk upright on two feet, also known as bipedal gait. The evolution of a permanent transverse and pedal arch are adaptations that help us to walk on land with two feet. Humans have dorsiflection of the metatarsal joints in the foot to help with the push-off phase and the ending stride of the bipedal gait. The transverse arches of our feet contribute to this dorsiflection of the metatarsals. We also have a stiff midfoot which allows the mid-foot and the hind-foot to lift off the group at the same time. Foot arches are a key factor in our day to day locomotion because of the mechanical advantage it gives us to propel off a surface. Apes on the other hand do not have arches in their feet because they use arboreal locomotion, meaning they spend most of their time on the trees.

Although it was known that a Hominin, Australopithecus afarensis was bipedal, it was not known if this species had a permanent transverse and longitudinal foot arch because an essential bone of the midfoot had not been found (a complete fourth metatarsal).

Ward and his collegues were able to obtain and analyze the fossil including the fourth metatarsal of A. afarensis foot and discovered that A. afarensis indeed had a permanent transverse and longitudinal pedal arch. Their paper supports that A. afarensis resembled modern day Homo Sapiens bipedal anatomy rather than ape anatomy. They measured torsion of the fourth metatarsal and data suggest that because of the increased torsion of the MT4, they can infer the presence of a transverse arch. This research shows that bipedality occured in early hominins and human foot anatomy as well as human pedal physiology occurred in early hominins. Evolution selection for terrestrial bipedality suggests that arboreal locomotion, as seen in apes and chimpanzees, were considered unfavorable.

Ward, C., Kimbel, W., Johanson, D. (2011). Complete fourth metatarsal and arches in the foot of Autralopithecus afarensis. Science; 331 (2), 750-753.

Electrical Stimulation to Partially Restore Mobility to Paralysis Patients

I had the opportunity to do an internship at the Functional Electrical Stimulation (FES) Center in Cleveland, OH. The FES Center is supported by two hospitals and Case Western Reserve University. The FES Center specializes in helping restore muscle function and control to paralysis patients. We had a patient who had been shot in the back of the neck severing most of her spinal cord in between the C1 and C2 vertebrae. She was paralyzed from the shoulders down and had some control of her left shoulder, left arm, and left hand. Since she could still control her neck muscles and partially control her left shoulder this allowed researchers at the FES Center to design her a system to partially restore daily functions.

Surgeons implemented EMG sensors in her platysma, neck, and left shoulder muscles. Surgeons also implemented nerve cuffs that surround single nerves. She also has a bundle of wires coming out of the abdomen that could plug into an external control unit (ECU) that was used to test and make adjustments to her system. Her system utilized the EMG recording in her muscles in combination with an algorithm to electrically stimulate nerve cuffs which would cause action potentials down certain nerves and cause muscles to contract.

For instance when she would slightly mover her left shoulder forward, the EMG sensors would record the activity in the left trapezoid muscle causing electrical stimulation of a nerve cuff that causer her right tricep to contract, which would cause her to extend her right arm. If she made a frown this would induce the platysma muscles and cause her right forearm and hand muscles to contract and make a fist. A different muscle contraction in the neck or face area would cause her right bicep to contract causing her right arm to flex back towards her body. This FES system in her body is not sophisticated enough to alter the magnitude of the electrical current sent to her nerves so unlike a normal person her muscles would completely contract making her either fully extend or fully flexed in a very robotic motion, and this is all done with her seated in her wheelchair.

Even though there is major limitations this does allow her to eat and drink with limited help and is big gain for daily activities for paralysis patients. The technology of using electrical stimulation to bypass an injured spinal cord and innervate paralyzed muscles has actually been around for about twenty years and is used in different parts of the body. It is used in the legs to help stand or keep standing and also in muscles to help in bladder control and swallowing. The FES Center also specializes in prosthetics and neural engineering that gives a futuristic feel. They are currently researching and have tested on primates what they call neuromotor prosthesis. They are attempting to use a brain implant and sensors to detect the intent to move directly from the brain to control prosthetics or use nerve cuffs to stimulate paralyzed limbs.

http://fescenter.org/index.php

Kirsch, R. Development of a neuroprosthesis for restoring arm and hand function via functional electrical stimulation following high cervical spinal cord injury.

Kirsch, R. Toward the Restoration of Hand Use to a Paralyzed Monkey: Brain-Controlled Functional Electrical Stimulation of Forearm Muscles.

The Teenage Brain

Although we may consider some of the actions and decisions teenagers are making completely outrageous, we cannot hold them entirely accountable for the sometimes negative consequences they endure due to poor reasoning skills. David Dobbs explores the science behind the teenage brain in his article, The Beautiful Brain, featured in the October issue of National Geographic.

Contrary to popular belief, the human brain is not done developing or maturing after elementary school. The brain goes through a massive upgrade as humans go through adolescence. This development is the biggest throughout the human life span and is responsible for essential reasoning skills. During this period, the axons transmission speed increases by one hundred times. This is due to the insulation of myelin, as we discussed previously in Animal Physiology class (it is not my fault, my brain is not fully myelinated). Also, the dendrites are growing stronger and more capable of passing signals. Another change that is contributing to the brains power is the thinning of the cortex while the corpus callosum thickens and improves the flow of messages throughout the brain. Basically, all of the components of the brain which allow for cognition are strengthened. This process allows for the brain to act more efficiently and quicker. The focus is on the front part of the brain and contributes to an individual’s complex thinking instead of basic skills such as movement. Dobbs describes this proceeding development as essential for “balancing our impulses, desires, goals, self-interest, rules, ethics, and altruism.”

The teenage brain acts differently than the adult brain. An example discussed in the article was how teenagers take much more risks in life than adults do. After much experimental research, the determining factor that induced the risk taking was the teenage brain being more attuned to oxytocin. This hormone allows teenagers to weigh the rewards of a successful risk differently than an adult would. The hormone also makes social connections more rewarding as well, possibly explaining while teens are more vulnerable to peer pressure.

The most essential organ to human existence is the brain. We can credit the not so thought out choices of teenagers to the fact that the frontal part of their brains is not as matured as an adult brain. This late maturation is all part of the body’s natural plan to ensure a successful adult life so myelination is postponed until these adolescent years. As Dobbs states, “It can seem a bit crazy that we humans don’t wise up a bit earlier in life. But if we smartened up sooner, we’d end up dumber.”

Dobbs, D. Beautiful brains. National Geographic. October 2011, Vol 220 Issue 4, page 37-54.

A correlation between contraceptive use and HIV infection?

A recently published article in the New York Times discusses the correlation between contraceptive use and incidence of HIV infection amongst certain African populations. Depo-Provera, designed by Pfizer, is a hormone injection that contains depo-medroxyprogesterone acetate (DMPA), a synthetic version of the progestin hormone. Injected quarterly, Depo-Provera inhibits pregnancy by one of three mechanisms: inhibiting ovulation, thickening the cervical mucus (which ultimately prevents sperm from swimming to the egg), or by altering the endometrial lining of the uterus to inhibit implantation (American Pregnancy Association). Generic versions of this injection, furthermore, are commonly used as contraceptives by thousands of women residing in southern and eastern Africa. In addition, many other injected hormones are used by approximately 12 million women (ranging from age 15-49) in sub-Saharan Africa, primarily because this method of contraception is simple and long-lasting. However, researchers from the University of Washington published a study that claims that injected hormones, like Depo-Provera, actually increase the risk of H.I.V. infection by twofold. Moreover, H.I.V. positive women who use injected hormones actually double the likelihood of H.I.V. transmission to a male partner. Although the exact mechanism is unknown, researchers postulate that the DMPA induces immunological changes in the vagina and cervix, or even potentially enhance the virus’ ability to replicate itself.

The University of Washington research finding creates a very perilous medical crux for many women, by forcing them to decide between unwanted pregnancy and potential HIV infection/transmission. According to a fact sheet released by the United Nations, the likelihood of a woman dying to pregnancy or childbirth complications in sub-Saharan Africa is 1 in 30, compared to 1 in 5,600 in developed nations. A similarly alarming problem is HIV infection: from the 33.4 million people living with this disease worldwide, two thirds of them reside in sub-Saharan Africa. The University of Washington researchers suggested that a potential solution to this dilemma is increased use of condoms and other forms of contraception like intrauterine devices and implants. In terms of ease, however, hormonal injections trump all of these alternatives.

After the release of the study, members of the World Health Organization have decided to meet and re-consider their decision to internationally support hormonal injections like DMPA. Personally, I feel like the most medically sound route would be to discontinue using the hormonal injections if it increases the incidence of HIV transmission and infection. However, I realize not everyone would agree with me, considering the wide-ranging effects of complicated pregnancies and deliveries for women in sub-Saharan Africa. What do you think?

To read the article published by Pam Belluck in the New York Times, please visit: http://www.nytimes.com/2011/10/04/health/04hiv.html?pagewanted=1&_r=1&ref=health

Sources Cited:

American Pregnancy Association. Accessed 6 Oct. 2011.

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