Chapter 099 Disorders of Hemoglobin (Part 12) ppsx

... that affect the LCR of the α-globin gene cluster. Diagnosis and Management of Thalassemias The diagnosis of β-thalassemia major is readily made during childhood on the basis of severe anemia ... the characteristic signs of massive ineffective erythropoiesis: hepatosplenomegaly, profound microcytosis, a characteristic blood smear (Fig. 99-5), and elevated levels of HbF, HbA 2...

Ngày tải lên: 07/07/2014, 04:20

... inherited disorders of α- or β-globin biosynthesis. The reduced supply of globin diminishes production of hemoglobin tetramers, causing hypochromia and microcytosis. Unbalanced accumulation of α ... critical clue. The best diagnostic test is methemoglobin assay, which is usually available on an emergency basis. Methemoglobinemia often causes symptoms of cerebral ischemia at...

Ngày tải lên: 07/07/2014, 04:20

... hypochromia, and hemoglobin levels rarely <1 g/L (<10 g/dL). Hereditary Persistence of Fetal Hemoglobin HPFH is characterized by continued synthesis of high levels of HbF in adult life. ... metering pump. The constant presence of the drug improves the efficiency of chelation and protects tissues from occasional releases of the most toxic fraction of iron—low-mol...

Ngày tải lên: 07/07/2014, 04:20

... Chapter 099. Disorders of Hemoglobin (Part 1) Harrison's Internal Medicine > Chapter 99. Disorders of Hemoglobin Disorders of Hemoglobin: Introduction Hemoglobin is ... stigmata. Hemoglobin Structure Different hemoglobins are produced during embryonic, fetal, and adult life (Fig. 99-1). Each consists of a tetramer of globin polypeptide chains: a...

Ngày tải lên: 07/07/2014, 04:20

... the ability of hemoglobin to deliver more oxygen to tissues at low pH. It arises from the stabilizing action of protons on deoxyhemoglobin, which binds protons more readily than oxyhemoglobin ... the tetrameric structure of the proteins, the proper arrangement of the charged amino acids, and interaction with protons or 2,3-BPG. Developmental Biology of Human Hemoglobins Red...

Ngày tải lên: 07/07/2014, 04:20

... biosynthesis) and of structural hemoglobinopathies (e.g., an abnormal amino acid sequence). Hereditary persistence of fetal hemoglobin (HPFH) is characterized by synthesis of high levels of fetal hemoglobin ... Hereditary persistence of fetal hemoglobin persistence of high levels of HbF into adult life V. Acquired hemoglobinopathies A. Methemoglobin due to toxic...

Ngày tải lên: 07/07/2014, 04:20

... of the complete blood cell count (e.g., profound microcytosis with minimal anemia in thalassemia trait). Detection and Characterization of Hemoglobinopathies—General Methods Of the ... mutant hemoglobins can usually be characterized by more specialized techniques such as isoelectric focusing and/or high-pressure liquid chromatography (HPLC). Quantitation of the hemoglobin pr...

Ngày tải lên: 07/07/2014, 04:20

... Chapter 099. Disorders of Hemoglobin (Part 5) Sickle Cell Syndromes The sickle cell syndromes are caused by a ... C:50% Pathophysiology of sickle cell crisis. Several sickle syndromes occur as the result of inheritance of HbS from one parent and another hemoglobinopathy, such as β thalassemia ... reticulocytes) that are abnormally adherent to the endoth...

Ngày tải lên: 07/07/2014, 04:20

... important for prognosticating the clinical severity of disease. Chapter 099. Disorders of Hemoglobin (Part 6) Clinical Manifestations of Sickle Cell Anemia Most patients with sickling ... increase in the hematocrit and feedback inhibition of reticulocytosis might be beneficial, even at the expense of increased blood viscosity. The role of adhesive reticulocyte...

Ngày tải lên: 07/07/2014, 04:20

... tests already discussed. Thorough characterization of the exact hemoglobin profile of the patient is important, because sickle thalassemia and hemoglobin SC disease have distinct prognoses or ... of retinopathy; antibiotic prophylaxis appropriate for splenectomized patients during dental or other invasive procedures; and vigorous oral hydration during or in anticipation of pe...

Ngày tải lên: 07/07/2014, 04:20