Sickle cell anemia is one of the all over the world famous diseases. What is that disease? What can it be caused by? How to find the appropriate treatment? Those are questions which a great number of scientists have been trying to find an answer since long time ago.
Sickle cell anemia is a hereditary disorder that mostly affects people of African ancestry, but also occurs in other ethnic groups, including people who are of Mediterranean and Middle Eastern descent. More than 70,000 Americans have sickle cell anemia. And about 2 million Americans – and one in 12 African Americans – have sickle cell trait (this means they carry one gene for the disease, but do not have the disease itself).
Sickle cell anemia is a blood disorder that affects hemoglobin a protein found in red blood cells that helps carry oxygen throughout the body. Red blood cells with normal hemoglobin (HbA) move easily through the bloodstream, delivering oxygen to all of the cells of the body. Normal red blood cells are shaped like doughnuts with the centers partially scooped out and are soft and flexible.
Sickle cell anemia occurs when a person inherits two abnormal genes (one from each parent) that cause their red blood cells to change shape. Instead of being flexible and round, these cells are more rigid and curved in the shape of the farm tool known as a sickle – that’s where the disease gets its name. The shape is similar to a crescent moon. Sickle cell anemia takes place when an abnormal form of hemoglobin (HbS) is produced. HbS molecules tend to clump together, making red blood cells sticky, stiff, and more fragile, and causing them to form into a curved, sickle shape. Red blood cells containing HbS can go back and forth between being shaped normally and being sickle shaped until they eventually become sickle shaped permanently. Instead of moving through the bloodstream easily, these sickle cells can clog blood vessels and deprive the body’s tissues and organs of the oxygen they need to stay healthy. The U.S. Department of Energy Biological and Environmental Research (2002), gives the model of sickle cell anaemia gene (see appendix, n. p.).
Unlike normal red blood cells that last about 4 months in the bloodstream, fragile sickle cells break down after only about 10 to 20 days, which usually causes anemia. Anemia is what happens when the body’s number of red blood cells (or amount of hemoglobin) falls below normal. People who are anemic often feel weak and tire more easily.
People with sickle cell anemia can also experience complications from blood circulation and infection-fighting problems. These include a higher risk of certain infections and stroke as well as a condition called acute chest syndrome, which is caused by infection or trapped red blood cells in the lungs.
Sickle cell anemia is not contagious, so one can’t catch it from someone else or pass it to another person like a cold or other infection. People with sickle cell anemia have inherited two sickle cell genes, one from each parent. A child who has inherited the sickle cell gene from only one parent will not develop the disease, but will have sickle cell trait. People who have sickle cell trait don’t have sickle cell anemia or symptoms of the disease, but they can pass the sickle cell gene to their own children.
Codominant inheritance of the sickle cell gene means that individuals homozygous for the mutation have clinical disease and that heterozygous individuals, although asymptomatic, are detectable. When an individual with sickle cell trait is considering conceiving a child with a mate who is heterozygous for Hb S, Hb C, or b thalassemia, there is a one-in-four chance for each pregnancy that the offspring will inherit a form of sickle cell disease. When one parent has sickle cell anemia and the other is heterozygous for any of these three disorders, there is a one-in-two chance with each pregnancy of conceiving a child with sickle cell disease.
Because people with sickle cell trait don’t have the disease, they may never discover that they carry the gene. That’s why it’s recommended that teens who are unsure of their sickle cell status ask their doctors about testing. The National Institutes of Health recommends that all newborns be screened for sickle cell disease, and testing at birth is now required in almost every state. This helps infants with sickle cell anemia get the care and treatment they need right away.
Although there is no cure for sickle cell anemia, doctors can do a great deal to help patients, a considerable approaches has been carried out in recent years and treatment is constantly being improved. Basic treatment of painful crises relies heavily on painkilling drugs and oral and intravenous fluids to reduce pain and prevent complications.
Blood Transfusions – Transfusions correct anemia by increasing the number of normal red blood cells in circulation. They can also be used to treat spleen enlargement in children before the condition becomes life-threatening. Regular transfusion therapy can help prevent recurring strokes in children at high risk.
Oral Antibiotics – Giving oral penicillin twice a day beginning at 2 months and continuing until the child is at least 5 years old can prevent pneumococcal infection and early death. Recently, however, several new penicillin-resistant strains of pneumonia bacteria have been reported. Since vaccines for these bacteria are ineffective in young children, studies are being planned to test new vaccines.
Hydroxyurea – The first effective drug treatment for adults with severe sickle cell anemia was reported in early 1995, when a study conducted by the National Heart, Lung, and Blood Institute showed that daily doses of the anticancer drug hydroxyurea reduced the frequency of painful crises and acute chest syndrome. Patients taking the drug needed fewer blood transfusions.
Regular health maintenance is critical for people with sickle cell anemia. Proper nutrition, good hygiene, bed rest, protection against infections, and avoidance of other stresses all are important in maintaining good health and preventing complications. Regular visits to a physician or clinic that provides comprehensive care are necessary to identify early changes in the patient’s health and ensure immediate treatment. Today, with good health care, many people with sickle cell anemia are in reasonably good health much of the time and living productive lives. In fact, in the past 30 years, the life expectancy of people with sickle cell anemia has increased.
The three particular historical episodes can be referred speaking about sickle cell anaemia. The first, of course, is when a physician, a Chicago physician James Bryan Herrick, in 1910 discovered what he labeled “peculiar elongated and sickle shaped red blood cells” in a young student from the West Indies, and speculated that this might be an indication of a new disease.
The second event often focused upon by historians occurred some 40 years later in 1949, and that is when scientist Linus Pollen speculated that this sickling phenomenon of red blood cells happened not because of some character of the cells themselves, but because the molecular structure of the hemoglobin inside these cells was at fault. Just as James Herrick is praised for his clinical insight, Pollen’s work has been often praised because it signals a new way of visualizing disease and disease mechanisms using the tools of a new science — molecular biology, a discipline that was only becoming more and more relevant to medicine in the 1950s, ’60s and today to comprehend and understand disease phenomenon.
A third episode often focused upon by historians marks the point at which the story apparently entered national politics and popular awareness. That is the passage in 1972, 23 years after Linus Pollen’s work, of legislation by the US Congress, signed into law by President Richard Nixon, providing federal funds, federal dollars, for new sickle cell research centres, new community-based clinics and genetic counselling programs. Even as this new legislation gave priority to this new disease, this national program also, as a result increased fears about the possibility of coercion that was associated with new mandatory screening policies. And it heightened concerns in many African-American communities that counselling parents of sickle cell children to not have more children amounted to a form of barely veiled, state-sponsored genocide. And it also provoked resentment on the other end of the political spectrum about that preferential treatment that was given to this one disorder, this one genetic disease over others.
Speaking about the achievement in treating the sickle cell anaemia one of the most prominent names one has to remember is Pauling. In chemistry, in addition to the Nobel Prize (1954), Pauling was given numerous awards, including the Davy, Pasteur, Willard Gibbs, T.W. Richards, G.N. Lewis, Priestley, Avogadro, and Lomonosov medals. He was the first recipient of the National Academy of Sciences Award in Chemical Sciences, in 1979. The National Library of Medicine gave him its Sesquicentennial Commemorative Award in 1986; he was given other notable medical awards, such as the Addis, Phillips, Virchow, Lattimer, and the French Academy of Medicine medals.
Pauling’s theory describes a sickling process. He stated many times that his work in immunology incited his immediate understanding of the sickling process. Indeed, Pauling proposed a similar mechanism for the sickling process as he had presented in 1940 to explain his theory about the formation of antibodies. Specifically, Pauling assumed that the globins differed from one another near where the iron attached, and that the sickling happened because a region in the globin of sickle cell anemia hemoglobin had a different surface area than normal hemoglobin. In the absence of oxygen, the two complementary regions of sickle cell hemoglobin molecules bind together forming long chains and therefore hinder blood flow in the body. In comparison, the presence of oxygen obstructs the two complementary regions from binding and the various red blood cells do not aggregate.
Moreover, their experiments proved Pauling’s theory that the abnormal structure of sickle cell hemoglobin causes the disease, sickle cell anemia. Their term “molecular disease” brought attention to the structural change at the molecular level. By linking a structural abnormality of a substance inside the human body to a disease, Pauling and his colleagues demonstrated that genes determine the structure of proteins, and that abnormal protein structure can cause a disease.
All the attempts made by prominent scientists all over the world prove that the sickle cell anemia still remains one of the most dangerous attributes of the world’s life. The world community must acknowledge that many approaches have been realized in order to find resolution of this great challenge. But still the world society must make this disease one of the focuses of effort of its future healthcare activities.
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