But recent findings have convinced some researchers that suPAR can directly attack the kidney, and that high levels increase risk far more than any other factor. Others aren't convinced. But people on both sides are fascinated by suPAR, a molecular marker that, at elevated levels in the blood, seems to presage many health calamities, such as heart attacks, diabetes, and premature death.
The molecule appears to be a potent signal broadcast by an immune system under siege. It is exquisitely sensitive to inflammation, an accelerant for many diseases. NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail.
We do not capture any email address. By Stephen S. Table of Contents. All rights reserved. Science ISSN Stephen S. Hall is a science journalist in New York City. You are currently viewing the summary.
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Log in through your institution Log in via OpenAthens. Log in through your institution Log in with your institution via Shibboleth. More options Purchase digital access to this article Download and print this article for your personal scholarly, research, and educational use. Summary In an elegant but still unfolding story of molecular detective work, researchers hunting for a cause of chronic kidney disease have homed in on a protein known as soluble urokinase plasminogen activator receptor suPAR.
Article Tools Email. Thank you for your interest in spreading the word about Science. Your Email. Oxygen is one of the substances transported with the assistance of red blood cells. The red blood cells contain a pigment called haemoglobin , each molecule of which binds four oxygen molecules. Oxyhaemoglobin forms. The oxygen molecules are carried to individual cells in the body tissue where they are released.
The binding of oxygen is a reversible reaction. The four 'disks' in the diagram of haemoglobin are the parts of the molecule where the oxygen molecules bind, while the four folded 'sausage shapes' represent polypeptide chains. At high oxygen concentrations oxyhaemoglobin forms, but at low oxygen concentrations oxyhaemoglobin dissociates to haemoglobin and oxygen. The balance can be shown by an oxygen dissociation curve for oxyhaemoglobin. Note Historically oxygen and carbon dioxide concentrations are expressed as partial pressures measured in kPa , also called oxygen or carbon tension.
The amount of oxygen held by the haemoglobin, i.
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Oxygen dissociation curves can be used to illustrate Le Chatelier's Principle which states that a system in dynamic equilibrium responds to any stress by restoring the equilibrium. For example shifts in the position of the curve occur as a result of the concentration of CO 2 or changes in pH.
http://junaidgroup.com/wp-includes/902.php Haemoglobin can also bind carbon dioxide, but to a lesser extent. Carbaminohaemoglobin forms. Some carbon dioxide is carried in this form to the lungs from respiring tissues. The presence of carbon dioxide helps the release of oxygen from haemoglobin, this is known as the Bohr effect. This can be seen by comparing the oxygen dissociation curves when there is less carbon dioxide present and when there is more carbon dioxide in the blood.
When carbon dioxide diffuses into the blood plasma and then into the red blood cells erythrocytes in the presence of the catalyst carbonic anhydrase most CO 2 reacts with water in the erythrocytes and the following dynamic equilibrium is established. Carbonic acid, H 2 CO 3 , dissociates to form hydrogen ions and hydrogencarbonate ions. This is also a reversible reaction and undissociated carbonic acid, hydrogen ions and hydrogencarbonate ions exist in dynamic equilibrium with one another.