Science of Strokes

types of strokesIt has been well accepted that atherosclerosis is the result of chronic inflammation. I have spent several years exploring the role endocannabinoids, lipid-based neurotransmitters that bind to receptors that are expressed throughout the peripheral and central nervous system, play in decreasing oxyradical derived inflammation. Under normal conditions, lipids are metabolized and excreted from the body. It is my belief we have an endogenous mechanism that maintains balance within the vascular system that protects our arteries from becoming damaged; however, in the event of an injury the immune system is activated leading to cardiovascular dysfunction.

Flow resistance, sheer stress, ischemic reperfusion, and oxidized low-density lipoproteins (oxLDL) can contribute to microvascular dysfunction particularly at non-linear area of a vessel. The pathology of atherosclerosis/stroke starts with the monocytes being recruited to an injured site causing the production of NADPH oxidase-derived reactive oxygen species (ROS). The monocytes undergo a phenotypic change into macrophages and uncontrollably engulf the oxLDL and subsequently lead to the development of lipid laden foam cells. Apoptosis of the foam cells occurs due to their inability to metabolize the modified reactive lipid peroxidation products. The extracellular matrix becomes remodeled resulting in the formation of a fibrous cap. It is this cap that causes the occlusion of a vessel causing a heart attack or stroke.

circulating moncyte, macrophage and foam cellAll strokes are not alike, they include ischemic, hemorrhagic, and transient ischemic attacks (TIA). Although older persons are thought to be the primary risk group for strokes, children and fetus can potentially be included in the risk population. The most common type is ischemic stroke caused by clots occluding the blood flow to the brain. The clots can be from congenital heart defects, sickle cell disease, and trauma that injures a large artery; however, they can also be a consequence of high cholesterol, oxLDL, and blood clots as well as exogenous and endogenous toxins. The foam cells in the artery can be either a stable plaque (solid fibrous extracellular tissue with small amounts of lipid) or vulnerable plaque (consist of macrophages and lipids in the artery wall that erosion prone). These “culprit” plaques are the cause of disruption in blood flow that leads to vascular events such as heart attacks and strokes. Hemorrhagic strokes are due to a rupture in the blood vessel that bleeds to the deep tissue of the brain; often caused by hypertension, but also aging vessels, arteriovenous malformations (cluster of deformed blood vessels), and aneurysms (a balloon of blood in the artery). Intracerebral hemorrhages are the most common type due to the prevalence of high blood pressure but can also be caused by exogenous toxins such as smoking, oral contraceptives with high estrogen, alcohol, and illegal drugs. TIAs often called mini-strokes, produce symptoms similar to those of stroke but without the lasting effects. They are thought to be warning signs to an ischemic stroke; the clots that cause them may be resolved without treatment, but without treatment they can lead to further strokes or death.

A recent report by Wang and colleagues demonstrated a linear correlation between oxLDL and the National Institutes of Health Stroke Scale (NIHSS). The results of their study indicated after adjusting for age, gender, ethnicity, and marriage, NIHSS score increased 1 μg/dL of oxLDL.  Preparedness is the best defense to preventing a stroke. The Hip-Hop Stroke randomized trial suggest that preparedness can potentially delay a major thrombolysis event. Visits to a medical professional to recognize the symptoms will play a major role in prevention. Since atherosclerosis and stroke are complex process that involve oxyradical stress, immune dysfunction, and vulnerable vessels and the NIHSS score is widely used in the clinical setting to evaluate LDLs in plasma, one can only delineate that being prepared by getting tested is the best way to validly and reliably be prepared to combat a stroke. If you find someone displaying stroke symptoms act FAST to give the best prognosis. Share with me your experience or experiences you have heard of to combat the detrimental effects of stroke.

Science of Strokes

Anberitha Matthews, PhD is a Postdoctoral Fellow at the University of Tennessee Health Science Center in Memphis TN. She is living a dream by researching vascular injury as it pertains to oxidative stress, volunteers with the Mississippi State University Alumni Association, serves as Chapter President and does consulting work with regard to scientific editing.

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