A Stroke of Insight

According to the CDC, every 40 seconds, a person in the United States has a stroke, and every 4 minutes, someone dies from one. It is the leading cause of disability and in the top five causes of death. The scariest part about it is that there may be no warning signs. A stroke happens suddenly with all of its symptoms happening at exactly the same moment. So what is this silent killer and what can be done to prevent it? A stroke is a lack of blood flow to the brain, either due to a blockage of blood in an artery or cranial hemorrhaging. When blood flow ceases, the brain gets oxygen deprived. This can cause fainting, numbness, slurred speech, loss of vision, and many other symptoms, depending on which part of the brain is lacking oxygen. It can often result in brain damage if the problem is not resolved.

Blockage of blood is called an ischemic stroke. The most common ischemic stroke is due to a blood clot in the brain, called a thrombus. They can also occur due to an embolus, large clumps of fat, atherosclerosis, cancer cells, or any other large clump in the blood. An embolus in a free-floating clot. They are common in the heart and are the second most common form of a ischemic stroke. This kind of stroke is due to generally due to a high blood pressure (BP). High BP can be caused from an improper diet, atherosclerosis, metabolic syndrome, obesity, a diet rich in low-density cholestrols, and many other things. As age increases, so does the risk of increased BP.

Hemorrhagic strokes account for one fifth of the total and due primarily to a faulty artery bursting in the brain. The artery can be thought of as a balloon. The more the balloon is blown up the more it gets stretched thin. Eventually just blowing it up in its normal fashion will cause it to burst. This is the same with the arteries in the brain. They get rubbed thin by blood passing by them, especially if the blood is thick due to an improper diet. Eventually, they rupture. This is called an aneurysm. Hemorrhagic strokes are often linked with previous head trauma and are the more dangerous of the two.

When the blood is blocked due to a build up in the arteries, the oxygen-deprived parts of the brain shut down. Sometimes the cases are so severe that the person must be admitted to a hospital and given a clot-busting drug to restore blood flow. Other times the build up of pressure behind the blockage is enough to push the clump through the artery allowing more blood to flow. When the blood is leaking out due to hemorrhaging, most often the patient will need surgery.

The most common surgeries are a intracranial or extracranial bypass and carotid endarterectomy. The bypass is a surgery used to reroute blood flow away from a plaque-infested or blocked pathway. It's like if the were in accident on the freeway and instead of clearing all the cars, they just reroute them permanently through a detour. An endarterectomy, shown on the right, is a procedure where surgeons remove build up of plaque. In this situation, instead of rerouting cars, they simply take out some of the slower cars to avoid any jam in the first place. After a stroke, a person may need to be in rehabilitation for speech, muscles, or work. If he or she was without oxygen for long enough they can cause serious brain damage as well as muscle damage, if the clot was formed elsewhere than the brain.

In either case, even after the blood has been restored, the person is still at a high risk for another stroke. In order to decrease the risk of another stroke, patients often take medication to reduce their blood pressure including diuretics, vasodilators, ACE inhibitors, beta blockers, and a variety of others. The most common medication taken after a stroke is aspirin, which reduces the platelet count. Platelets are the blood cells that help in clotting. An aspirin a day has been shown to reduce the chance of a stroke.

In order to prevent a stroke, it doesn't hurt to take an aspirin a day, but the most important thing is to eat right and keep blood pressure at a normal level. Eating foods high in high-density cholestrols will help in the removal of unwanted clumps in the blood stream. The best foods in this case are ones that are not high in fat. This will also reduce the amount of free fatty acids in the blood, which are the cause of atherosclerosis. Eating healthy and going to the doctor often are the best ways to live a healthy life.

“Aneurysms.” A.D.A.M. Medical Encyclopedia, PubMed Health, 13 August 2010. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002109/

Imholtz, Alex. “Blood Questions.” Anatomy and Physiology at Prince George's Community College. http://academic.pgcc.edu/~aimholtz/AandP/PracticeQuestions/Blood/bloodq2.html

“Relating to Heart - Atoguard & Atoprin (Atenolol+Amlodipine+Aspirin).” Perk, 2012. http://www.perk.in/ato-guard-prin-folder-product-information.htm

“Stroke: Hope through Research.” National Institute of Neurological Disorders and Stroke, 6 September 2012. http://www.ninds.nih.gov/disorders/stroke/detail_stroke.htm#214271105 

Images:

http://www.michiganstrokenetwork.com/Treatment/Overview/v/Hemorrhagic/patients.aspxOverview/v/Hemorrhagic/patients.aspx

http://www.vascularweb.org/vascularhealth/Pages/endarterectomy.aspx

http://www.perk.in/ato-guard-prin-folder-product-information.htm

Speed your recovery....practice massage?!

The connection between innate and adaptive immunity absolutely requires the lymphatic system.  Dendritic cells are phagocytic cells that reside at interfaces between the body and the external environment.  At sites of inflammation, immature dendritic cells take up foreign particles and enter the lymphatic system.  These are very low pressure specialized vessels meant to drain excess fluid from tissues and also aid in immunity.  Lymphatic flow is particularly slow (like a trickle), meaning that a dendritic cell carrying information about a foreign invader may not reach a lymph node for days!  The lymph node is the site where the dendritic cell can present antigen and activate an adaptive immune response characterized by the activation of T and B cells. A major component of the delay between innate and adaptive immune responses is the slow moving lymph!  This brings up an interesting idea, that someone in class had mentioned during lecture.  Can athletes speed recovery from infection compared to sedentary individuals because they perturb their lymph to move faster through physical movement?  The answer may be yes, but say you are a couch potato.  Should you miss out of opportunities to speed your recovery?

This is when I stumbled upon Manual Lymphatic Drainage (MLD) massage.  This is a type of gentle massage (that therapists must take special classes in order to receive certification!) meant to aid or speed natural lymphatic drainage and flow.  Scouring through many websites I have found that this massage is a common therapy for lymphedema but also claims that it can boost immunity, reduce swelling and pain, release toxins, and even reduce stress! Even more spectacularly, I found a youtube video showing how to do self lymphatic massage!  But just be careful, because if you push with too much force you can actually collapse the lymphatic vessel and be in a worse spot than you were before.  Intriguing?  Cooky? What do you think?

Your Brain on Pathogens

YOUR BRAIN ON PATHOGENS

The reading in class and the discussion in the last class has made me interested in what actually happens with the blood brain barrier (BBB) and antibodies when something foreign enters the brain. There are many diseases that I can think of that cause neurological problems which lead me to believe that some bacteria or viruses actually do, or can, cross the blood brain barrier.

The examples that I could think of were West Nile Virus (WNV) and Meningitis. Meningitis is inflammation of the meninges; in this case the inflammation is being caused by some foreign marker such as bacteria. The brain needs some kind of defense to be able to protect itself or our species would likely no longer exist. Although the BBB needs to be extremely specific to make sure we don’t have an immune response to our own brain. I believe that we do have immune responses that are brain specific.

The following is the information that I discovered while researching this topic.

The brain does not have a lymphatic system that can initiate an immune response from the body to the brain. Antibodies are not able to enter the brain through the BBB, which for our brains, creates a major problem in order to control infection via bacteria, viruses, or even some parasites that are able to cross the BBB.  Seeing white blood cells in the brain is something that is possible but it seems to be very rare in cases of severe disease. Since we know that phagocytes are not specific in what they target they can actually cause more harm to the body’s normal cells while they are engulphing and killing the infected cells. In turn this could destroy neurons and other essential elements of the brain; not good.

In the recent research articles that I was reading through it seems that the brain does have some sort of its own immune system.  These immune cells that are in the brain are called microglia and they form an extensive defense network in the brain without the need of the Lymph System to help fight disease and foreign pathogens. Microglial cells are essentially the innate immune system of the brain. Like the immune system of the body they respond not only to injury of the brain but also to foreign pathogens that get past the BBB. Microglial cells cause inflammation when activated, similar to the peripheral innate immune system, so it’s worth asking if these cells do more harm than good when there is a pathogen in the brain. It does not seem that swelling in the brain would be anything to look lightly at as there is very little room for expansion in the skull. The microglial cells that are in the brain work without harming the neuronal tissue.

 Astrocytes are another cell in the brain that helps with the brains immunity. These cells respond more vigorously in the brain than do the microglial cells.  It seems that neurons will also express a type of protein that is a paired- immunoglobin-like receptor which can inhibit the brain’s plasticity, this protein is expressed in the neurons and aids in brain trauma. In the case of parasites entering the brain, such as toxoplasmosis (think kitty litter), the brain will actually respond with T cells that can cross the BBB and enter the brain. It seems that little is known about this process but I find it very interesting that these cells are allowed to cross the BBB at a time of parasite toxicity. Perhaps the T-cells are already in the brain; I’m not sure on this one, anyone have some insight?

Ultimately what I found out about the immune system of the brain seems like I’m barely scratching the surface. There is so much more to the brain’s immune system than I ever would have thought to begin with.  I’m looking forward to learning more about it in class and in my own time. There are tons of research articles on this topic and it seems as if scientist though researchers have only just begun to understand the brain’s immune system.

http://www.nature.com/nri/journal/v9/n6/fig_tab/nri2565_F5.html

 References:

Molecular Medicine Reports, May 8, 2012, http://www.spandidos-publications.com/mmr/6/2/339

Stimulating the brain’s immune response may provide treatment for Alzheimer’s disease, Jan 26, 2011, http://phys.org/news/2011-01-brain-immune-response-treatment-alzheimer.html

Science Daily, Brain Structure Assists in Immune Response. Jan 30,2009. http://www.sciencedaily.com/releases/2009/01/090128132652.htm

Drawing test to help predict stroke death risk?

I was researching ways to assess the risk of stroke and came across an article about a drawing test that could be administered to a patient that would help to predict your likeliness to die after having a stroke. This idea is interesting to me because it reminds me of brain teasers and things like that, that doctors give to patients with dementia or Alzheimer's in order to keep their brain in tip top shape. This study was conducted by researchers in Sweden and they took a group of 919 white men (they had no history of a stroke incident) and administered a Trail Marking Test. This cognitive test is basically where you have to mark a line in between letters and numbers that have been scattered on the page, in ascending order. The participants progress was monitored over a 14 year period and the age range was from 69 to 75 years old.

One thing about this study that I have an issue with is they don't really mention how this test can possible help to predict whether or not someone will have a stroke and I think that its a more helpful test to measure the amount that someone has recovered after suffering a stroke. I'm still unclear as to how this test will help to predict whether or not you would survive a stroke. I think that in order to explore this type of test being beneficial, they need to broaden their pool of participants and instead of just being white men from 69 to 75 they should test several different age ranges that are known to be the point at which the risk of having a stroke increases. They should also branch out to see if race plays a factor in this type of test. Like they pointed out in the study, there is nothing that is really invasive in this whole process so people don't really feel the need to opt out of the study.

I'd be interested to see the other ways people come up with to help predict risk factors. 

http://www.nhs.uk/news/2012/05may/Pages/stroke-prediction-drawing-test.aspx

Eating Chocolate=Reduce Risk of Stroke?

In the United States, about 700,000 Americans have a stroke, while 160,000 die from stroke-related causes every year.  Strokes are the most common cause of adult disability and adult loss of independence.  A stroke can leave one person with a scar, manifesting itself anywhere from a persons physical appearance to internal damage.  It can leave someone with a neurological problem or a cardiovascular problem.   This “brain attacker” seems find ways to cause more trouble ranging from disease to death.  Neurological researchers and funded stroke foundations and associations have taken it upon themselves to find ways to prevent and treat stroke victims, but before one can attempt to find a cure, one must understand what exactly a stroke is. 

A stroke is the when the circulation of blood to the brain fails, and in turn brain cells die due to lack of oxygen from decreased blood flow.  Strokes are divided into two categories, which is based on cause: ischemic and hemorrhagic.  Ischemic stroke is the lack of blood flow to the brain due to blockage.  Comprising approximately 80 percent of all strokes, these kinds of strokes can come in three different flavors: thrombosis, which is a clot in a blood vessel in the brain or neck, embolism, which is a clot moving from different parts of the body, and an embolism, which is the stenosis of arteries leading to the brain.  Hemorrhagic strokes are termed for bleeding into spaces around the brain. 

Overtime, several warning signs of a stroke have been discovered and national organizations have published various lists of signs and symptoms that patients should be aware of.  Some warning signs include sudden numbness (especially on one side of the body), confusion, vision trouble, motor and balance difficulties, or a seemingly idiopathic headache. 

Risk factors of a stroke can be divided into two different categories: modifiable (or treatable) and non-modifiable.   The non-modifiable risk factors include age, gender, ethnicity, or genetics.  Modifiable risk factors include hypertension, cigarette smoking, cardiovascular disease, history of having transient ischemic attacks (AKA “mini strokes”), diabetes, cholesterol imbalance, obesity and sedentary lifestyle. 

In researching on basic information on strokes and such, I came upon an article in regards a possibility of reducing stroke.  It was recently published in an online journal of the American Acaademy of Neurology that eating a moderate amount of chocolate weekly can reduce the risk of stroke in men.   A study  conducted in Sweden used 37,103 men ages 49 to 75 who were given a food questionnaire on how often they consumed various foods.  After cross-listing in the hospital discharge registry, they found that only approximately 2000 of those men had a first stroke in the past 10 years.  It was found that the men in this sample who had the largest amount of chocolate, which was 1/3 a cup of chocolate chips, had a lower risk of stroke. 

It was found in an analysis of 5 studies that included 4,260 stroke cases that the risk of stroke for individuals in the highest category of chocolate consumption (which is not disclosed) was 19 percent lower than to non-chocolate consumers.  It was found that “for every increase in chocolate consumption of 50 grams per week, or about a quarter cup of chocolate chips, the risk of stroke decreased by about 14 percent”. 

It is believed that the stroke risk reduction is related to the flavonoid content of chocolate.  Flavonoids have been found to be protective against cardiovascular disease via their antioxidant, anti-clotting and anti-inflammatory properties.  It is also believed that flavonoid content can help reduce the amount of cholesterol in blood.

My issue with this particular article is that they do not include how they assess the risk of stroke, or try to discuss if or why chocolate has that effect on ages 49-75.  I do not believe they even cite the studies that they derive the information from. If they included more details of the study, I believe that the experiment outcome would be more believable.   

The science behind it may be somewhat correct. However, the research articles that I have been finding that review such things may be considered weak evidence.  There are still ongoing studies to discover the answer to one question: Could chocolate really lower your risk of stroke?  Or is it possible that we are we just trying to find an excuse to indulge in the sweet treat?

http://www.sciencedaily.com/releases/2012/08/120829171933.htm

I found another article studying the same subject.

http://www.sciencedaily.com/releases/2010/02/100211163114.htm

More Honey, More Problems

It is common knowledge nowadays that Americans are getting larger. The convenience of a McDonald's or a Taco Bell can be seen in every state. With all the skinny celebrities out there, people often try to lose weight by taking a certain type of food out of their diet. In truth, Americans need to eat less overall and have a balance of all types of food. More than anything, they need to exercise. The excess fat in a human body may just appear to be a social issue, but it's an extreme health issue. It causes obesity, metabolic syndrome, and type 2 diabetes, which can cause more complications in your eyes, skin, heart, brain, ears, feet, bone and kidneys. In fact, type 2 diabetes is the “leading cause of kidney failure, non-traumatic lower-limb amputations, and new cases of blindness.” (Center for Disease Control and Prevention). But how does it make the transition from just excess body fat to a life-threatening disorder?

Obesity is a buildup of fat, specifically visceral fat or abdominal fat. The typical test for obesity is a Body Mass Index (BMI) test, calculated using a person’s weight (in kilograms) over height (in meters) squared. By definition, a person is obese if their BMI is over 30 kg/m². The BMI test does not reflect fat distribution, however, so often times just measuring the waist circumference of a person can show the level of obesity. MRIs can also show a dispersion of fat.

Obesity is one of the core components of Metabolic Syndrome, originally called “Syndrome X.”  Metabolic Syndrome is the combination of any of a lot of core pathologies that together create an increased risk of cardiovascular disease. The main pathologies include insulin resistance, hyperinsulinemia, glucose intolerance, visceral obesity, dyslipidemia, and essential hypertension.  The International Diabetes Foundation (IDF), The National Cholesterol Education Program, and The World Health Organization all have slightly different definitions as to how to diagnosis metabolic syndrome, but overall they agree that hyperinsulinemia and obesity are they top signs.

There are multiple ways for these pathologies to arise. When fat and glucose are not being broken down at proper rates, due to lack of exercise or overeating, they build up in the bloodstream. The hormone insulin will tell the muscle cells to start taking in the glucose. The cell has to constantly be breaking them down to lower the blood glucose levels. But if the cell is working on overdrive to break down the metabolites, eventually it gets tired and starts breaking down less despite the same stimulus from insulin. This is insulin resistance. The pancreas can not tell that the muscle cells are resistant. All it can tell is that the blood glucose levels are too high, so it dumps more insulin in the blood to tell cells to take more out. This is how hyperinsulinemia occurs. Glucose intolerance is the next step. The easy test for this is an oral glucose tolerance test (OGTT). After overnight fasting, the patient is given a sugary drink to see how the body will handle the increase of glucose consumption. After a two hour period, the blood will drawn and blood glucose levels measured. Anything under 140 mg/dl is healthy. Above 140 mg/dl shows glucose intolerance. A result above 200 mg/dl means the patient has type 2 diabetes.

Type 2 diabetes is often confused with type 1 diabetes. Type 1 diabetes is generally genetic, and it is when the body does not produce enough insulin. This results in cells not getting enough glucose and therefore can cause fatigue, increased hunger, and increased thirst. These people need insulin injections daily to cope with their disease. Type 2 diabetes does not require any injections. Their bodies have produced more insulin than they have needed in the past due to overeating fatty or sugary foods. Now the excessive insulin in the blood triggers less of a stimulus. While there may have been a genetic predisposition for type 2 diabetes, it was ultimately their life choices that brought them to this disorder. According to the Center for Disease Control, as of 2011, 25.8 million people worldwide have diabetes.

The three main causes of diabetic complications are hypertension, high blood glucose levels, and dyslipidemia. Dyslipidemia is an abnormally high amount of cholesterols and fats in the blood. It is caused from hyperinsulinemia of insulin-resistant individuals. The insulin in the blood is a stimulant for adipocytes to release free fatty acids into the blood stream to be broken down in muscle cells. The muscle cells are not taking any fat or glucose in though, due to the resistance to insulin. Hypertension is also caused by hyperinsulinemia. The high glucose levels causes renal water retention, which leads to increased cardiac output due to either higher stroke volume or faster heart rate. Overall, the increased cardiac output leads to higher blood pressure, hypertension.

The combination of these three symptoms leads to many complications, however diabetes is not a death sentence. Every year more studies are coming out linking diabetes to more and more diseases, but if the disease is managed properly there is no need for such complications. With a proper diet and daily exercise, insulin-resistance can be reversed. There are also medications out to decrease each of the symptoms of metabolic syndrome to prevent type 2 diabetes in the first place. The important thing is to maintain a healthy, active lifestyle.

References:

Centers for Disease Control and Prevention. “National diabetes fact sheet: national estimates and general information on diabetes and prediabetes in the United States, 2011.” Atlanta, GA: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, 2011.

 “Diabetes.” Medline Plus, National Institute of Health, 2 July 2012. http://www.nlm.nih.gov/medlineplus/diabetes.html

“Healthy Weight – it’s not a diet, it’s a lifestyle!” Centers for Disease Control and Prevention, 13 September 2011. http://www.cdc.gov/healthyweight/index.html

Mayo Clinic. “Glucose Tolerance Test.” Mayo Foundation for Medical  Education and Research, 2010. http://www.mayoclinic.com/health/glucose-tolerance-test/MY00145

“What is Type 1 Diabetes (T1D)?” Juvenile Diabetes Research Foundation. http://info.jdrfdsw.org/what-is-type1diabetes.php

Also (not sure how to reference)

Dr. Henriksen’s PSIO303A class at the University of Arizona

ASK YOURSELF: If you could turn any antigen into a tolerogen, which would you choose?

I wanted to take the time to go over one of the questions that Dr. Cohen asked within the notes, I decided to answer this question above (in the title).

An antigen is something that is recognized by the body and in return, it signals an immune response referred to as an immunogen. For example, toxins, bacteria, foreign blood cells etc. A tolerogen is something that does NOT cause an immune response, but rather, prevents an immune response.

In order to be able to change any antigen into a tolerogen, you first want it to be  something with which the body will be able to function normally in the presence of it. But this is a hard thing, if something is already an antigen, it is technically already designated as a bad foreign thing, so I am not positive that it would be good for the body to function normally in the presence of any antigen turned tolerogen. Does this make sense?

However, one example of an antigen that I think would greatly be of benefit if turned into a tolerogen is an organ specific antigen. Each organ has its own particular antigen that distinguishes it from any other organ. One thing though, that I am not sure of is: is this antigen specific between that particular organ in question between species, or is it specific to that particular organ within an individual? If it is the latter I think that changing this organ specific antigen into a tolerogen would be of great use in organ and tissue donation and it could potentially decrease the number of rejections experienced by recipients of those organs.