Sickle cell anemia research paper

Sickle cell anemia research paper

Sickle Cell Anemia Research Papers look at one of the most common inherited blood disorders. Sickle cell anemia research papers examine the disease that is an inherited blood disorder. Medical health writers research the disease and give the most recent information in a custom written paper. Sickle cell anemia, (SCA) one of the three distinct types of sickle cell disease, is the most common inherited Sickle cell anemia (SCA) is the homozygous state, where the individual inherits the beta S gene from both parents, so that only Hb S is made. Hemoglobinopathy SC results from the inheritance of the gene for beta S from one parent and the gene for beta C from the other parent, so that both Hb S and C are produced in approximately equal amounts Global scientific research output on sickle cell disease: A comprehensive bibliometric analysis of web of science publication Sickle cell disease (SCD) remains a global public health problem in sub-Saharan Africa and other countries. Limited information is available on the scientific research productivity on SCD

Sickle-Cell Disease Research Paper - EssayEmpire

This sample Sickle-Cell Disease Research Paper is published for educational and informational purposes only. If you need help writing your assignment, please use our research paper writing service and buy a paper on any topic at affordable price.

Also check our tips on how to write a research papersee the lists of health research paper topicsand browse research paper examples, sickle cell anemia research paper. This group of diseases is found in sickle cell anemia research paper frequency in sub-Saharan Africa, the Mediterranean countries, the Middle East, sickle cell anemia research paper, and India but is also widely distributed throughout Europe and the United States, as well as Central and South America, sickle cell anemia research paper.

A reduced oxygen tension allows the Hb S molecule to polymerize, causing distortion of the RBC into the characteristic half-moon shape. Sickled cells cause intermittent obstruction of the blood vessels vasoocclusion leading to ischemia reduced blood flow and infarction tissue death as well as anemia and other morbid complications.

Inside each RBC are millions of molecules of Hb. Four globin protein chains and four iron-binding protoporphyrin heme molecules make up each Hb molecule. The globin chains stabilize and solubilize the heme and facilitate oxygen uptake in the lungs and release in the tissues. There are three types of normal hemoglobin, each made up of a different combination of the four normal globin chains a, b, g, and d globins.

The typical compositions of Hbs in normal and disease states are given in Table 1. Fetal hemoglobin is the primary type for the infant while in the uterus, as it is better able to take up oxygen from the relatively low levels present in the placenta. As sickle cell anemia research paper child ages, beta chain production gradually replaces gamma chains so that Hb A replaces Hb F by 6 months of age.

At this time, sickle cell anemia research paper, the clinical features of a beta chain abnormality like Hb S become evident; signs of the disease such as hemolytic anemia are detectable, and symptoms of the disease may begin. There are two sickle cell anemia research paper chain genes located on chromosome 16, while single beta, gamma, and delta chain genes are on chromosome Therefore, each chromosome in a pair controls half the total globin chain production.

Each globin chain gene guides the RBC to make a specific globin chain; the globin chains match with a heme and then assemble into a complete Hb molecule. Hemoglobin sickle cell anemia research paper are of two main types: structural and synthetic. Structural hemoglobinopathies are due to a change in the amino acid sequence of either alpha or beta globin because of an alteration in the DNA sequence of the corresponding globin gene. Some of these genetic defects in the Hb molecule cause serious disease by causing anemia or by interfering with the oxygenation function of the molecule.

On the other hand, many of these abnormal hemoglobins do not affect the way that Hb works and cause no symptoms at all. Synthesis defects are caused by a genetic change in the factors that control normal globin chain production, so that either alpha or beta globin is underproduced. This type of hemoglobinopathy produces a group of disorders known as the thalassemia syndromes; as in those with sickle cell trait, thalassemia is believed to provide partial protection from malaria and occurs in high prevalence in the Mediterranean area, the Middle East, and southeast Asia.

More than mutations producing beta thalassemia have been described. Alpha thalassemia is most often due to a deletion of one or more of the two alpha globin alleles on chromosome 16, but over 20 additional genetic defects producing alpha thalassemia have been described. Nearly hemoglobins that differ in structure or function from the normal molecule, Hb A, have been discovered.

Basic information on these variants has been collected by Hardison et al. Sickle hemoglobin is due to a mutation in codon 6 of the beta globin gene, wherein an adenine to thymine substitution results in the substitution of valine for glutamic acid in the beta globin chain. This substitution allows the Hb S molecules to bind to one another when deoxygenated.

Considerable scientific evidence indicates that the Hb S gene arose in several regions of Africa, the Mediterranean area, and some southeast Asian countries as partial protection against falciparum malaria.

Recent work has shown that some degree of the clinical heterogeneity is related to modifying genes that influence, positively or negatively, the clinical complications through modulation of Hb F expression, bilirubin catabolism, stroke, and iron loading, for example. The search for additional factors that contribute to the variability of disease expression depends upon demonstration of a cause-and-effect relationship, and the results of such studies are eagerly awaited. There are three common forms of sickle cell disease.

Table 1 summarizes the hemoglobin composition in normals, in the common forms of sickle cell disease, and in the carrier state, sickle sickle cell anemia research paper trait. Table 2 provides a typical picture of the blood counts in these conditions. Sickle cell anemia SCA is the homozygous state, where the individual inherits the beta S gene from both parents, so that only Hb S is made. Hemoglobinopathy SC results from the inheritance of the gene for beta S from one parent and the gene for beta C from the other parent, sickle cell anemia research paper, so that both Hb S and C are produced in approximately equal amounts.

The sickle thalassemias result from the inheritance of one gene for beta S and one for beta thalassemia. Consequently, the hemoglobin composition varies with the severity of the beta thalassemia gene defect, from zero production to near normal production Table 1. Other hemoglobins may be co-inherited with Hb S but are less frequent; disease results when the second hemoglobin participates in the polymerization process. Hbs F and A inhibit polymerization and have an overall beneficial effect.

On deoxygenation, the presence of valine Hb S instead of glutamic acid allows adjacent Hb molecules to bind to each other, sickle cell anemia research paper. As additional binding occurs, polymerization of the Hb S molecules produces tubular fibers that distort the cell into the characteristic sickled shape. When the sickle cell anemia research paper is reoxygenated, the Hb S fibers melt, and the cell returns to the biconcave round shape. Hb S polymerization occurs when the oxygen tension within the RBC is lowered but is accentuated when RBCs are exposed to acidosis low pHhigh temperature feverand increased osmolality dehydration.

After several cycles of sickling and unsickling, the RBC becomes permanently damaged. The denser RBCs increase the blood viscosity, with a reciprocal diminution in blood flow and increasing risk of vasoocclusion.

These dense sickle RBCs are more rigid than the normal RBCs and are destroyed easily, shortening their life span to 15 days, sickle cell anemia research paper, rather than the normal days.

Bone marrow production of RBCs increases to keep up with the rate of destruction. Even at maximum output, the marrow is unable to manufacture enough cells to maintain a normal Hb level and chronic hemolytic anemia results. When RBCs are destroyed, the components of Hb are catabolized. The protoporphyrin in heme is broken down into bilirubin, which the liver excretes into the gallbladder sickle cell anemia research paper bile.

Vascular occlusion by sickle RBCs occurs at the postcapillary venule, leading to ischemia from lack of oxygen beyond the obstruction to blood flow, cell death necrosis in the poorly perfused area, and, ultimately, healing by fibrosis scar tissue. Vasoocclusion is responsible for the signs and symptoms of this disease, sickle cell anemia research paper. The size sickle cell anemia research paper the obstructed vascular area and the amount and duration of the ischemia determine the degree of pain or organ damage.

Although vascular occlusion can affect any of the body organs, certain vascular beds are particularly susceptible; these include the bone marrow, spleen, lung, kidney, and bones. Vasoocclusion in the sickling disorders is the result of a complex interaction involving the sickle RBC, the endothelial cells lining the blood vessels, leukocytes, and platelets, along with coagulation factors and other plasma proteins. Sickle RBC adherence to endothelium is the sine qua non of this interaction and is mediated by a number of cell surface receptors on the RBC and on the endothelial cell.

Plasma proteins have a significant role as bridging molecules mediating adhesion pathways between RBCs and endothelial cells Chiang and Frenette, A summary of these interactions is presented in Table 3. The most common form of sickle cell disease is SCA. Hemolytic anemia is present by the age of 6 months, sickle cell anemia research paper, although vascular occlusion symptoms may not appear until later.

The anemia in SCA tends to be severe Table 2. Much useful information on the clinical course of this disease has been the result of reports from the Cooperative Study of Sickle Cell Disease in the United States Platt et al.

Recurrent vasoocclusion leads to ischemic destruction of the spleen, which predisposes the patient to severe infections. Until recently, bacterial infections were the most common cause of death in children. Now, prophylactic treatment with antibiotics as reported by Gaston et al. Children with sickle cell anemia frequently have delayed growth and a delay in the onset of puberty. Delayed growth and sexual maturation appear to be related to nutritional factors, although the exact mechanism is still not clear.

There is wide variation in disease manifestations and severity Platt et al. The long-term effects of recurrent vascular occlusion, ischemia, infarction, and fibrosis may cause one or more types of chronic organ damage, and the management of organ complications may become a major issue.

The most common causes of death in these individuals are infections, stroke, lung disease, and sickle cell anemia research paper renal failure. The median survival determined by the Cooperative Study of Sickle Cell Disease is 42 years for males and 48 years for females Platt et al.

A low Hb F level, an elevated white blood cell WBC count, sickle cell anemia research paper, and severe anemia are predictors of premature mortality and reflect an underlying inflammatory state indicative of severe disease. Currently, hematopoietic stem cell transplantation is the only curative therapy for this disease. Its application is limited due to a lack of human leukocyte antigen-matched siblings without disease.

Additional trials of low-intensity preparative regimens or using unrelated donors are underway, attempting to find a way to expand the potential recipient population. Gene therapy remains an achievable goal, and much progress has been made in recent years.

Investigators in the United States and in France are just beginning human trials of gene therapy Bank et al. In hemoglobinopathy SC, Hb S and Hb C each make up half the hemoglobin composition Table 1. Hemoglobinopathy SC is less common than SCA. By the time an infant is 6 months old, hemolytic anemia will be evident; however, vasoocclusive symptoms are often delayed until early adulthood. The anemia is less severe than that of SCA Table 2.

Crises and infections are less frequent than in SCA, although occasional patients have severe disease Platt et al. Bone disease aseptic necrosis and retinal vessel involvement sickle retinopathy are more common than in SCA, whereas other types of organ damage are less common. The median survival of 60 years for males and 68 years for females is only slightly less than that in the U.

African-American population. Sickle thalassemia results from the inheritance of one beta S gene and a thalassemia defect on the other beta gene. In S beta thalassemia β Othe thalassemic globin gene prothe Hb S chromosome.

Sβ O thalassemia is similar to sickle cell anemia in its hematology, disease onset, course, and prognosis. There is no disease associated with sickle cell trait. Those individuals with sickle cell trait have received one gene for beta S from one parent and one for beta A from the other parent. Although the RBCs of these individuals do not normally sickle in vivo, they can be induced to do so in the laboratory under extreme deoxygenation.

Therefore, the RBC survival is normal, and there sickle cell anemia research paper no anemia. These individuals do not have the symptoms and signs of vasoocclusion, such as acute pain, frequent infections, or chronic organ damage, with two exceptions.

Damage to the kidney may lead to hyposthenuria inability to concentrate the urineand splenic infarctions have been described in some. These two examples of end-organ damage are related to extreme environmental stress. Hyposthenuria is related to the high concentration of solute in the medulla of the kidney, which accentuates the sickling process locally and can damage the kidney concentrating mechanism.

Splenic infarct is usually reported in persons exposed to high altitude, where exercise, hypoxia, dehydration, and acidosis may accentuate Hb S polymerization, leading to splenic infarct.

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Research Paper On Sickle Cell Anemia. Sickle cell anemia (SCA) is a genetic disorder that is hereditary. It affects the blood, and is caused when the hemoglobin in blood cells are deprived in oxygen from the proteins. These cause normal round blood cells, to have are rigid sickle shape. People affected by SCA have a higher risk of death, stroke, severe attacks, and severe rushes of pain Sickle cell anemia (SCA) is the homozygous state, where the individual inherits the beta S gene from both parents, so that only Hb S is made. Hemoglobinopathy SC results from the inheritance of the gene for beta S from one parent and the gene for beta C from the other parent, so that both Hb S and C are produced in approximately equal amounts Sickle Cell Anemia Research Papers look at one of the most common inherited blood disorders. Sickle cell anemia research papers examine the disease that is an inherited blood disorder. Medical health writers research the disease and give the most recent information in a custom written paper. Sickle cell anemia, (SCA) one of the three distinct types of sickle cell disease, is the most common inherited