Human diseases Sickle cell anemia

Consider the human genetic disease sickle cell anemia. In the normal p-chain of hemoglobin, the sixth amino acid is glutamic acid. In the p-chain of sickle cell hemoglobin, the sixth amino acid is valine. How did this amino acid substitution arise The answer lies in examination of the codons for glutamic acid and valine ... 

Until recently it was thought that all adult human beings had the same kind of hemoglobin molecules in their red cells. Then it was discovered that an abnormal form of hemoglobin is present in the red cells of people suffering from the disease sickle-cell anemia, and more recently still other abnormalities have come to light. 

A few years ago it was discovered that the disease sickle-cell anemia is a disease of the hemoglobin molecule the patients with this disease manufacture abnormal molecules of hemoglobin, rather than normal adult human hemoglobin, and there is strong indication that the abnormal molecules of hemoglobin are directly responsible for the symptoms of the disease. Since then it has been discovered that there are a number of other hereditary hemolytic anemias that are caused by abnormal kinds of human hemoglobin. Several review articles in this field have been published recently. - > ... 

Humans given zinc supplements should be aware of possible complications (Fosmire 1990). Low intakes of 100 to 300 mg of zinc daily in excess of the recommended dietary allowance of 15 mg Zn daily may produce induced copper deficiency, impaired immune function, and disrupted blood lipid profiles. Patients treated with zinc supplements (150 mg daily) to control sickle cell anemia and nonresponsive celiac disease developed a severe copper deficiency in 13 to 23 months normal copper status was restored by cessation of zinc supplements and increased dietary copper (Fosmire 1990). 

From a nutritional viewpoint, Cu2+ competes with zinc ion, as does the very toxic Cd2+. The latter accumulates in the cortex of the kidney. Dietary cadmium in concentrations less than those found in human kidneys shortens the lives of rats and mice. However, some marine diatoms contain a cadmium-dependent carbonic anhydrase.11 Although zinc deficiency was once regarded as unlikely in humans, it is now recognized as occurring mider a variety of circumstances0 p and is well-known in domestic animals.01 Consumption of excessive amounts of protein as well as alcoholism, malabsorption, sickle cell anemia, and chronic kidney disease can all be accompanied by zinc deficiency. 

Through the late 1950s, Pauling still dabbled in science. He remained interested in the medical applications of his work and wrote pieces about sickle-cell anemia and the role of abnormal molecules in human disease. He toyed with the idea that perhaps misshapen molecules were the cause of mental diseases. But he had lost the passion and focus that had marked his earlier work. 

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