Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Single-dose and steady-state pharmacokinetics of the new oral iron chelator, 1,2-dimethyl-3-hydroxypyrid-4-one (L1) were studied in 14 patients with thalassemia and correlated with iron excretion. Food prolongs the rate of absorption of L1, but it does not affect significantly the extent of absorption measured by the area under the plasma concentration-time curve. Similarly, it does not affect the chelation potential of the drug. The mean elimination half-life of the drug is 3 hours, suggesting that a divided dose every 8 hours may assure better chelation. Our steady-state studies reveal that urinary iron excretion is independently influenced by body iron load (measured by ferritin levels) and by steady-state trough concentrations of the drug. While patients were receiving an unchanged regimen of 75 mg/kg/day, we have detected a gradual and significant decrease in trough concentrations in the presence of unchanged patients' compliance monitored by the Medication Event Monitoring System, diaries, and pill count. These findings suggest self-induction of L1 metabolism or decreased absorption during long-term therapy. Because of the concentration-dependent iron excretion, patients may need increasing doses to achieve negative iron balance.
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PMID:Relationship between the pharmacokinetics and iron excretion pharmacodynamics of the new oral iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one in patients with thalassemia. 191 64

The cores of ferritins isolated from different organs of human subjects with beta-thalassemia/hemoglobin E (beta-thal/HbE) disease have different size distributions and crystallinities depending on the source organ. These patients have not been treated by hypertransfusion regimen or iron chelation therapy. beta-Thal/HbE spleens and livers yield ferritin cores which are less crystalline than those isolated from normal spleens and livers, reflecting the more rapid deposition of iron in the diseased state. Ferritins isolated from the hearts and pancreases of beta-thal/HbE subjects were found to have larger, more crystalline cores than those from the beta-thal/HbE livers and spleens, possibly as a consequence of the role of the heart and pancreas as long-term iron deposition sites in this iron overload pathology.
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PMID:Organ-specific crystalline structures of ferritin cores in beta-thalassemia/hemoglobin E. 193 35

A study of 10,378 school children of 6-17 years old from six southern and northern provinces of china, where there was no hookworm disease or thalassemia was made. All the children selected were healthy, with normal development and well nourished. Abnormal children and national minorities were excluded. After taking vermifuge before experiment, the subjects were given FeSO4 tablet 100 mg/day for 60 days, at same time they were given dietary instructions. Hb was measured before taking FeSO4 and two weeks after stop taking the drug. Based on the results of Hb values of children with supplemented iron, deriving percentile curves, according to percentile 5 and the reference suggestions used at home and abroad, the following (criteria) for screening anemia of Chinese children are suggested: [table: see text]
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PMID:[Study of screening criteria for anemia among school children in China]. 203 13

In patients with thalassemia treated by long-term chronic blood transfusions who survive beyond the first ten or twenty years of life but received no or inadequate chelating therapy during the first years, evaluation of iron overload and its consequences on tissues may prove an arduous task. MRI is a non-invasive means of measuring the amount of iron in the liver and the consequences of the iron overload on the heart and other tissues. For this purpose, MRI is more satisfactory than CT scan studies. In this investigation, 20 patients with thalassemia major underwent MRI. Multiple spin echos were used to allow determination of the transversal relaxation constant T2. This constant, expressed in ms, is related to the concentration of iron in the liver as in the following expression: (C) = 5 410/T2-110. MRI studies disclosed a discrepancy between the severity of hepatic hemosiderosis and development of decompensated iron overload cardiomyopathy. In a unique case, in which a heart transplant and two MRI studies were performed, the severe iron overload that failed to respond to several years of subcutaneous chelating therapy was more than halved by intensive intravenous chelation through a central catheter. MRI studies of the heart provide valuable morphologic and functional data. Although the amount of iron in the myocardium cannot as yet be quantified, modifications of the transversal relaxation time provide information on the severity of the overload and the presence of other myocardial alterations.
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PMID:[The value of nuclear magnetic resonance in the study of iron overload in thalassemia patients]. 203 85

Depending upon the transferrin saturation value, 214 serum samples were divided into three groups--iron overloaded (46 cases), iron deficient (61 cases) and normal (107 cases)--and tested with a micromethod based upon detection of unsaturated iron binding capacity. All the samples with iron overload could be distinguished from the other two groups, the results of the normal and iron deficient groups showing wide scatter and overlap. The high prevalence of iron deficiency anaemia and thalassaemia (iron overload) syndromes in India and other developing countries emphasises the need to differentiate these disorders at the earliest opportunity. The micromethod can be of immense help as it is a simple, rapid and inexpensive.
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PMID:Iron overload: detection using a micromethod for iron-binding capacity. 206 80

A study was conducted on 447 healthy high school students of southern Chinese descent to determine the prevalence of anaemia and thalassaemia. Haematological data and serum ferritin levels were determined on all venous blood samples. Haemoglobin (Hb) electrophoretic study was conducted on 43 students who had anaemia (Hb less than 12 g/dL), and/or mean corpuscular volume (MCV) less than 80 fL. They were re-assessed after 1 month of oral iron therapy. Three girls had definite iron deficient anaemia (less than 1%). Thirty-nine students had either alpha, or beta-thalassaemia, only seven of whom showed anaemia. Since the overwhelming majority of both the thalassaemic students (38 of 39) and the participants (429 of 447) were of Cantonese extraction (native of Guangdong province), the overall incidence of 8.8% (alpha-thalassaemia 5.4%, beta-thalassaemia 3.4%) reflected the high frequency of the thalassaemia gene among this group of southern Chinese. MCV measurement, rather than Hb, was more useful in its detection.
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PMID:Anaemia and thalassaemia in healthy adolescents from southern Chinese families. 207 20

Ferritins from liver and spleen of both beta-thalassaemia/haemoglobin E (HbE) and non-thalassaemic patients were purified by heating a methanol-treated homogenate, followed by molecular exclusion chromatography. The concentrations of ferritins in the beta-thalassaemia/HbE liver and spleen were calculated as 3.8 and 2.0 mg/g wet tissue. The beta-thalassaemia/HbE ferritin iron/protein ratios were higher than those of normal ferritins. On PAGE, all ferritins gave a single major monomeric band with only very small differences in their mobility. Ferritins from thalassaemic patients also possessed bands corresponding to oligomers. On SDS/PAGE, all ferritins were resolved into two major subunits: H and L with L subunit predominating. While the isoferritin profiles of ferritins from beta-thalassaemia/HbE liver and spleen were similar to each other and to those of normal liver and spleen, some extra bands were present in the acidic region. The microstructure of these pathological ferritins appears to result, to a large degree, from the particular nature and amount of iron loading present.
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PMID:Beta-thalassaemia/haemoglobin E tissue ferritins. I: Purification and partial characterization of liver and spleen ferritins. 207 62

Tissue ferritins from beta-thalassaemia/haemoglobin E heart and pancreas were characterized by native PAGE, SDS/PAGE and isoelectric focussing, and compared with those isolated from corresponding liver and spleen tissue. On PAGE, all ferritins consisted of a single band assigned to the protein monomer. Small differences in electrophoretic mobility were found between the bands. The ferritins were resolved by SDS/PAGE into two major subunits, H and L, corresponding to molecular masses of 22.5 kDa and 19 kDa, respectively. The L subunit was predominant in all cases. The isoferritin profiles of all tissue ferritins were remarkably similar, consisting of a complex pattern of bands which were appreciably more basic than those obtained for horse spleen ferritin. The subunit composition and isoferritin profiles of the four tissue ferritins almost certainly reflect the defense mechanism of the body in synthesizing in all four tissue types a more stable long-term iron-storage isoferritin in order to detoxify and store the excess iron present due to the pathological condition of beta-thalassaemia/HbE.
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PMID:Beta-thalassaemia/haemoglobin E tissue ferritins. II: A comparison of heart and pancreas ferritins with those of liver and spleen. 207 63

Iron overload is frequently present in patients with thalassemia intermedia, and it becomes evident mainly after the second and third decades of life. The degree of the iron load is heterogeneous ranging from mild to severe. In this study we evaluated the iron status of 38 adult patients with thalassemia intermedia and we looked for factors possibly related to the observed heterogeneity of the iron status. The levels of transferrin saturation (TS), serum ferritin (SF) and desferrioxamine-induced urinary iron excretion (DFU) were spread in a wide range from normal to markedly increased. These indices did not correlate with other parameters such as age, hemoglobin levels and entity of the erythropoietic status. A significant difference in the degree of iron overload was observed between patients who underwent splenectomy and non-splenectomized patients. TS, SF and DFU were significantly higher in splenectomized than in non- splenectomized patients, indicating that the spleen could have a role in the regulation of iron metabolism in these patients.
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PMID:Iron metabolism in thalassemia intermedia. 208 86

A long-term clinical trial of 1-15 months has been carried out with the oral iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1) in 13 transfusion-dependent iron-loaded patients. Urinary iron excretion was greatest in patients with thalassaemia major and was related to the number of previous transfusions but not to the serum ferritin level. Substantial increases of urinary iron were observed in all the patients when the frequency of the daily dose was doubled and in response to 2 x 3 g L1 daily 11 of 12 patients tested excreted greater than 25 mg iron daily, the mean daily intake of iron from transfusion. Serum ferritin levels have fluctuated but overall have remained unchanged. Pharmacological studies in five patients have indicated rapid absorption probably from the stomach and variable plasma half life of 77 +/- 35 min (X +/- SD). Glucuronation was identified as a major route of L1 metabolism. Short-term intensive chelation studies using repeated administration of L1 resulted in further increases of urinary iron excretion by comparison to a single dose. In one case 325 mg of iron were excreted in the urine following the administration of 16 g (5 x 2 g + 2 x 3 g) within 24 h. Iron excretion studies were carried out in six transfusional iron-loaded patients who were maintained on a low iron diet before and during chelation. No significant increases of faecal iron excretion were observed with L1 using daily doses of up to 3 x 3 g and 4 x 2 g. The high level of compliance during treatment with L1 and the levels of urine iron excretion that can be achieved increase the prospects for oral chelation in transfusional iron-loaded patients.
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PMID:Long-term trial with the oral iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1). I. Iron chelation and metabolic studies. 209 33


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