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Resia Pretorius is a Professor in the department of Physiology, University of Pretoria. She is also Director of the Applied Morphology Research Centre at the University. She has published over 150 research articles in rated scientific journals. She has also been study leader to 28 MSc and PhD students. In December 2011, she was named as winner of the African Union Kwame Nkrumah Scientific Awards for the Southern Region in the category: Basic Science, Technology and Innovation.

Tuesday, April 10, 2012

The Formaldehyde Debate: Are our beauty products harming us?

Report in Longevity Magazine: April 2012

Formaldehyde is currently used in many beauty products, and examples are the Brazilian Blowout as well as acrylic nails. It can be recognized by a very strong and distinct smell. This product is also used in preserving human tissue. Although it is used in beauty products, it is a known carcinogen (cancer causing agent), with no safe levels of use. Due to the fact that only scheduled products are regulated in South Africa, it rests upon us as consumers to educate ourselves about the products that we use. Is this, however, our responsibility to research every single product? Where does the responsibility lie?

Wednesday, November 2, 2011

The ultrastructure of stroke

Stroke is one of the leading causes of death world wide. There are two main devisions of stroke, namely haemorrhagic stroke, caused mainly by bleeding in the brain; and thrombotic stroke. This is caused by a thrombus or blood clot. This may develop due to a changed coagulation profile, resulting in a matted and dense fibrin clot. This is visible under an electron microscope when creating a clot, by taking citrate blood from an individual, and mixing it with thrombin. This thrombin addition causes a cascade of biochemical pathways to be activated, just as what typically will happen in the human body. A changed coagulation profile, as seen during stroke, may therefore be detected using a simple and cheap morphological screening tool. Follow-up investigations, after a stroke, can also be done to determine the success of the treatement.

The Micrograph shown here, shows the ultrastructure during stroke. Dense matted deposites (arrows) are formed in the body and this may block blood vessels.

Preventing stroke is one of the most important medical issues! Keep healthy by taking anti-oxidants, 5 to 7 portions of fruit and vegetables and DO NOT SMOKE. Smoking does not only impact negatively on your skin and aging, it is one of the main causes of stroke.

See a recently published article in Journal of Thrombosis and Thrombolysis by Pretorius and co-workers

The full text article is avialable at:

Tuesday, May 3, 2011

Thrombosis and Pregnancy

An important issue raised by one of the bloggers is the fact that during pregnancy, there is a tendancy for thrombosis. Remember, stroke can result is either haemorage of a blood vessel or clotting of a vessel, typically formed by fibrin mass or "clot".

During preganancy, the haemostatic status changes, to, amongst others, accomodate and prepare the body for child birth. An important factor here is that the body does not want too much blood loss and therefore, in normal pregnancy there is an increase in procoagulant activity. Also, the fibrinolytic activity (breaking up of fibrin after it has formed) is impaired and remains low during labor and delivery, but returns rapidly to normal, following delivery.

In a 2009 article in Blood, Coagulation and Fibrinolysis, my research team showed ultrastructural changes in fibrin networks found in pregnant individuals and compared this to non-pregnant individuals. Typically thick, major fibers and irregularly placed thin, minor fibers are present in healthy, non-pregnant individuals. In this qualitative assessment, changes in fibrin networks and platelet morphology were studied with scanning electron microscopy in healthy individuals, a healthy individual at 30 weeks pregnancy and post partum. These morphological changes seen during pregnancy might contribute to increased thrombotic risk, because, due to the denser appearance of fibrin networks due to the fine minor network morphology during pregnancy, clots might take longer to be broken down by normal fibrinolytic activity.

E Pretorius, P Bronkhorst, S Briedenhann, E Smit, RC Franz. 2009. Comparisons of the fibrin networks during pregnancy, non-pregnancy and pregnancy during dysfibrinogenaemia using the scanning electron microscope. Blood, Coagulation and Fibrinolysis 20(1):12-16.


Tuesday, April 19, 2011

Stop the Clot Campaign

Blood clots are a major cause of disease. It may cause heart attacks, strokes and thrombosis (blockage of blood vessels). In your blood, you have small particles, called platelets. Also, in the watery part of your blood, called the plasma, you have plasma proteins circulating in the blood. Platelets and these plasma proteins work together and are in equilibrium if you are healthy. Your body sometimes needs the platelets and plasma proteins to react on events that disrupt the homeostasis* (for definition see previous blogs) (balance of the body). An example of this may be a small wound to your skin or even inside your body. A blood clot forms when platelets and plasma proteins form a small plug consisting of activated platelets and plasma proteins that after a trigger, form a meshwork or network of fine fibers to cover the damaged area. During normal homeostasis the body will break down the clot area and this is called lyses. If we smoke, have too mutch stress or high blood pressure and cholestrol, it will disturb our balance or general homeostasis. This will cause clots to form excessively or without a definite trigger. Also, these clots may then break down less effectively. This may trigger the clot to break loose and this may lead to heart attacks and stroke, depending where the clot is formed. Smoking is one of the major triggers for disruption in your homeostasis. Lets start a campaign to STOP THE CLOT by spreading our science knowledge!

Monday, April 18, 2011

Smoking and sticky fibrin fibers

We all know that smoking is bad for our health. However, do you know that research has proven that it also impacts on your coagulation system, and therefore on hemostasis and balance of your body? We know that smoking has a very visible effect on your skin. Perhaps not when you are in your twenties, but look at women particularly who have been smoking for ten years of longer. Unfortuanately, smoking impacts greatly on your platelets and fibrin networks. Researchers that have shown the impact of smoking on the coagulation system include:

Armani et at., in the journal Current Pharmacy, 2009; 15:1038 -1053

Erhardt et al., in the journal Artherosclerosis, 2009; 205: 23-32

In research conducted by my research team at the University of Pretoria in 2010, we looked at how smoking affects the fibrin networks of healthy individuals who smoke (under ethical clearance). We drew blood from these individuals and sentrifuged the sample (this means we spinned the blood very vast in a machine called a centrifuge). We obtained plasma, which is the watery part of the blood.In the plasma, we find the plasma proteins and platelets that play a role in normal coagulation. In the body, if the coagulation cascade is triggered by e.g. damage to a small vessel inside the body, fibrin fibers will form. This is a natural process that will occur in all healthy individuals. In the body this network formations is facilitated by a special protein called thrombin. If we add thrombin to the plasma in the lab, we will mimic this fibrin creation process that will spontanously happen in the body when we have a small injury to e.g. a blood vessel. Therefore, if we add thrombin to the blood of a smoker, we can see how the smokers coagulation process via the fibrin networks, will look like. We use an electron microscope to view the fibers, as it is a very powerful instrument that can magnify up to a million times!

We found something very interesting when looking at the fibrin fibers of smokers. Their fibers seem to be sticking together and we coined a term: sticky fiber phenomenon when you smoke. What does this mean to your health? When you smoke, the toxins that you take in, affects the proteins in your plasma, and when you have a small injury e.g. in a blood vessel, you will form abnormally sticky fibrin networks. You may even perhaps spontanously form these thickened nets in your circulating blood. These thickened nets may struggle to break down by the normal process called lyses. If these thickened masses break loose it may cause you to have stroke or thrombosis. Unfortuanately, it is well-known that smoking causes stroke and thrombosis. This research was published in the journal Ultrastructural Pathology in 201o by Pretorius and co workers.

See the electron microscopy photo of a sticky fiber mass generated from the plasma of a smoker.

Your body, hemostasis and equilibrium

One of the most important functions of our body to keep us healthy, is to be in total equilibrium or balance. Therefore, all our systems must function in sinc with each other. An important part of this balance, is the functioning of our coagulation system. A simple definition for our coagulation system is how our blood reacts inside our body. We need a fine balance between bleeding and clotting. This process of is dependant on different pathways in our body that invloves small particles, called blood platelets and molecules that circulate in our blood plasma - the watery part of our blood. If we have a small wound after hurting ourselves, our platelets and plasma proteins will undergo a natural process of coagulation to try to prevent too much blood loss. This will result in a cascade of reactions that will form small thread-like fibers, that we call fibrin fibers. These fibers form nets over the wound to prevent further blood loss. You can see the nets in the electron microscope photo added to the post. After the formation of the nets, we need to lyse or break up the fibers again, especially if these fiber form inside our bodies, otherwise we form blood clots. So, you can see that we need a fine balance between formation of fibirn nets and breaking up of these nets. If our bodies do not for fibrin nets during injury, we may bleed too much and if our bodies do not break the nets up successfully, our equilibirum or balance is impaired. This may cause thrombosis, heart attacks and general bad health. Sometimes, external factors in a healthy individual, can cause a disturbance of equilibrium of this hemostasis. An example of this is smoking. In my next post I will discuss research that shows how smoking disturbes the coagulation system. Lets make sense of science!