Glycoproteins erythropoietin

Q10 Adult red blood cells are produced by the bone marrow at the ends of long bones and in the pelvis, skull, ribs and sternum. In response to severe anaemia the active bone marrow in the long bones becomes more extensive. Normally, the total number of circulating red blood cells is maintained constant. Production is stimulated by the glycoprotein erythropoietin (EP), which is mainly produced by the endothelial cells of the kidney. EP production is stimulated by hypoxia and a decrease in haemoglobin concentration. EP stimulates the stem cells in bone marrow to differentiate into mature erythrocytes. 

Matsumoto S, Ikura K, Ueda M, et al. Characterization of a human glycoprotein (erythropoietin) produced in cultured tobacco cells. Plant Mol. Biol., 1995 27(6) 1163-1172. 

The CSFs, as well as the glycoprotein erythropoietin, act at picomolar (10-12) concentrations by binding to their respective cell-surface receptors. 

Anemia may occur in patients with chronic renal failure as tlie result of the inability of the kidney to produce erythropoietin. Erythropoietin is a glycoprotein hormone synthesized mainly in the kidneys and used to stimulate and regulate the production of erythrocytes or red blood cells (RBCs). Failure to produce the needed erythrocytes results in anemia Two examples of drug used to treat anemia associated with chronic renal failure are epoetin alfa (Epogen) and darbepoetin alfa (Aranesp). 

Human erythropoietin is a glycoprotein of 166 amino acids (molecular mass about 34 kDa). Its amount in plasma can be measured by radioimmunoassay. It is the major regulator of human erythropoiesis. Erythropoietin is synthesized mainly by the kidney and is released in response to hypoxia into the bloodstream, in which it travels to the bone marrow. There it interacts with progenitors of red blood cells via a specific receptor. The receptor is a transmembrane protein consisting of two different subunits and a number of domains. It is not a tyrosine kinase, but it stimulates the activities of specific... 

Erythropoietin is a glycoprotein hormone that regulates the proliferation, differentiation, and maturation of erythroid cells. The EPO receptor is a member of the class 1 cytokine receptor superfamily. The crystal structure of an EPO-mimetic peptide and the extracellular portion of the... 

Erythropoietin Erythropoietin (EPO) (Fig. 4.8) is a glycoprotein produced by specialized cells in the kidneys. It has 166 amino acids and a molecular weight of approximately 36kDa.EPO stimulates the stem cells of bone marrow to produce red blood cells. It is used to treat anemia and chronic infections such as HIV and cancer treatment with chemotherapy where anemia is induced. Patients feel tired and breathless owing to the low level of red blood cells. EPO can be prescribed instead of blood transfusion. 

Erythropoietin concentrated solution Ph.Eur. Identification Series of closely related glycoproteins na ... 

Erythropoiesis (A). Blood corpuscles develop from stem cells through several cell divisions. Hemoglobin is then synthesized and the cell nucleus is extruded. Erythropoiesis is stimulated by the hormone erythropoietin (a glycoprotein), which is released from the kidneys when renal O2 tension declines. 

Pharmacology Erythropoietin is a glycoprotein that stimulates red blood cell production. It is produced in the kidney and stimulates the division and differentiation of erythroid progenitors in bone marrow. Hypoxia and anemia generally increase the production of erythropoietin, which in turn stimulates erythropoiesis. In patients with CRF, erythropoietin production is impaired this deficiency is the primary cause of their anemia. Epoetin alfa stimulates erythropoiesis in anemic patients on dialysis and those who do not require regular dialysis. 

Maintenance of red cell volume is critical to having an adequate oxygen supply to the tissues [10]. Healthy individuals finely balance erythropoiesis and erythrocyte loss and maintain constant hematocrit. The glycoprotein hormone erythropoietin is the principal controller of the homeostatic mechanism that links tissue oxygen delivery to red cell production. While hypothesized as early as 1863, unequivocal evidence of erythropoietin was first published in 1953. A few years later, scientists showed that animals subjected to bilateral nephrectomy were unable to mount an erythropoietin response to hypoxia. Indeed, the kidneys produce about 90% of circulating erythropoietin. 

A. General description Erythropoietin is a glycoprotein normally produced in the kidneys and is responsible for the stimulation of red blood cell production. Epoetin alfa is derived via recombinant DNA techniques by mammalian cells after the insertion of the human erythropoietin gene its amino-acid sequence is identical to that of endogenous erythropoietin. Epoetin alfa... 

These studies demonstrating a protective effect of sialic acid residues on serum glycoproteins provide an explanation for earlier, conflicting observations about the biological effect of, for example, desialylated erythropoietin, which stimulates erythropoiesis only after direct application to bone-marrow cell-cultures, and not after injection into the blood stream.469 In the latter experiment, only the native, sialylated hormone was active. Rapid clearance and inactivation of follicle-stimulating hormone,470 or interferon,471 after treatment with sialidase may be explained by uptake into liver cells. 

Epoetin alfa, recombinant erythropoietin, is a glycoprotein that simulates erythrocyte production. Epoetin alfa is administered three times weekly subcutaneously or intravenously. Epoetin is used to treat anemia in patients with chronic renal failure, HIV infection, and patients receiving chemotherapy [104]. Development of a safe, effective nasal formulation of epoetin alfa, containing an absorption enhancer could once again improve the efficacy of epoetin alfa therapy, and reduce the number of injections required in these sensitive patient populations. 

Erythropoietin, a 34-39 kDA glycoprotein, was the first human hematopoietic growth factor to be isolated. It was originally purified from the urine of patients with severe anemia. Recombinant human erythropoietin (rHuEpo, epoetin alfa) is produced in a mammalian cell expression system... 

The preparation methods for the glycoprotein antigens were varied. Myeloma protein was obtained from ascite fluid [25], The glucoamylase was from A niger [26], the erythropoietin was from recombinant hampster cells [27] and tumor glycoprotein was from colon tumor tissue [28]. 

Erythropoietin [ery throw PO eetin] is a glycoprotein, normally made by the kidney, that regulates red cell proliferation and differentiation in bone marrow. Human erythropoietin, produced by recombinant DNA technology, is effective in the treatment of anemia caused by end-stage renal disease, anemia associated with HIV-infected patients, and anemia in some cancer patients. Supplementation with iron may be required to assure an adequate response. The protein is usually administered intravenously in renal dialysis patients, but in others the subcutaneous route is preferred. Side effects such as iron deficiency and an elevation in blood pressure occur. [Note The latter may be due to increases in peripheral vascular resistance and/or blood viscosity.]... 

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