Asunto(s)
Terapia por Quelación , Trasplante de Células Madre Hematopoyéticas , Quelantes del Hierro/uso terapéutico , Sobrecarga de Hierro/tratamiento farmacológico , Leucemia Mieloide Aguda/terapia , Agonistas Mieloablativos/farmacología , Síndromes Mielodisplásicos/terapia , Acondicionamiento Pretrasplante , Adulto , Terapia por Quelación/efectos adversos , Deferoxamina/efectos adversos , Deferoxamina/uso terapéutico , Monitoreo de Drogas , Terminación Anticipada de los Ensayos Clínicos , Estudios de Factibilidad , Estudios de Seguimiento , Trasplante de Células Madre Hematopoyéticas/efectos adversos , Humanos , Infusiones Intravenosas , Infusiones Subcutáneas , Quelantes del Hierro/administración & dosificación , Quelantes del Hierro/efectos adversos , Leucemia Mieloide Aguda/complicaciones , Persona de Mediana Edad , Agonistas Mieloablativos/efectos adversos , Síndromes Mielodisplásicos/complicaciones , Proyectos Piloto , Acondicionamiento Pretrasplante/efectos adversos , Trasplante Homólogo , Adulto JovenRESUMEN
Thalassemia is a chronic, inherited blood disorder, which, in its most severe form, causes life-threatening anemia. Advances in treatment have led to increased life expectancy however the need for chronic blood transfusions and chelation therapy remains a significant burden for patients. Our study compared health related quality of life (HRQOL) from the Thalassemia Clinical Research Network's (TCRNs) Thalassemia Longitudinal Cohort (TLC) study to US norms and assessed association with clinical variables. There were 264 patients over age 14 who completed the Medical Outcomes Study 36-Item Short Form Health Survey version 2 (SF36v2) baseline assessment. When compared to US norms, TLC patients had statistically significant (P < 0.05) worse HRQOL on five of the eight subscales (physical functioning, role-physical, general health, social functioning, and role-emotional) and on both summary scales (physical component summary and mental component summary). Women, older patients, and those with more disease complications and side effects from chelation reported lower HRQOL. In general, adolescents and adults with thalassemia report worse HRQOL than the US population, despite contemporary therapy. The SF-36 should become a standard instrument for assessing HRQOL in thalassemia to determine predictors of low HRQOL which may be better addressed by a multidisciplinary team.
Asunto(s)
Talasemia/fisiopatología , Talasemia/psicología , Adolescente , Adulto , Estudios de Cohortes , Femenino , Encuestas Epidemiológicas , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Calidad de Vida , Encuestas y Cuestionarios , Estados Unidos , Adulto JovenRESUMEN
Thiamine-responsive megaloblastic anaemia with diabetes and deafness (TRMA; MIM 249270) is an autosomal recessive disease thought to be due to a defect in thiamine (vitamin B1) transport. Pharmacological doses of thiamine correct the anaemia, and in some cases improve the diabetes, although progressive sensorineural deafness is irreversible. Previous studies localized the TRMA gene to a 4-cM region on chromosome 1q23.3 (ref. 5), and fine-mapping has recently narrowed that region further. We have previously demonstrated that fibroblasts from people with TRMA lack high-affinity thiamine transport. Expression of a gene encoding a known yeast thiamine transporter, THI10 (refs 8-10), in TRMA mutant cells prevents apoptotic cell death in thiamine-depleted medium. On the basis of these studies, we hypothesized that a defective thiamine transporter causes TRMA. We undertook a candidate gene approach to identify putative thiamine transporters in the 1q23.3 critical region. Here we present evidence that the gene SLC19A2 (for solute carrier family 19 (thiamine transporter), member 2) encodes the first known mammalian thiamine transporter, which we designate thiamine transporter-1 (THTR-1).
Asunto(s)
Anemia Megaloblástica/genética , Proteínas Portadoras/genética , Sordera/genética , Diabetes Mellitus/genética , Proteínas de Transporte de Membrana , Mutación , Tiamina/metabolismo , Secuencia de Aminoácidos , Anemia Megaloblástica/complicaciones , Anemia Megaloblástica/tratamiento farmacológico , Animales , Secuencia de Bases , Línea Celular , Cartilla de ADN/genética , ADN Complementario/genética , Sordera/complicaciones , Complicaciones de la Diabetes , Humanos , Datos de Secuencia Molecular , ARN Mensajero/genética , ARN Mensajero/metabolismo , Homología de Secuencia de Aminoácido , Síndrome , Tiamina/uso terapéuticoRESUMEN
We have investigated the cellular pathology of the syndrome called thiamine-responsive megaloblastic anemia (TRMA) with diabetes and deafness. Cultured diploid fibroblasts were grown in thiamine-free medium and dialyzed serum. Normal fibroblasts survived indefinitely without supplemental thiamine, whereas patient cells died in 5-14 days (mean 9.5 days), and heterozygous cells survived for more than 30 days. TRMA fibroblasts were rescued from death with 10-30 nM thiamine (in the range of normal plasma thiamine concentrations). Positive terminal deoxynucleotide transferase-mediated dUTP nick end-labeling (TUNEL) staining suggested that cell death was due to apoptosis. We assessed cellular uptake of [3H]thiamine at submicromolar concentrations. Normal fibroblasts exhibited saturable, high-affinity thiamine uptake (Km 400-550 nM; Vmax 11 pmol/min/10(6) cells) in addition to a low-affinity unsaturable component. Mutant cells lacked detectable high-affinity uptake. At 30 nM thiamine, the rate of uptake of thiamine by TRMA fibroblasts was 10-fold less than that of wild-type, and cells from obligate heterozygotes had an intermediate phenotype. Transfection of TRMA fibroblasts with the yeast thiamine transporter gene THI10 prevented cell death when cells were grown in the absence of supplemental thiamine. We therefore propose that the primary abnormality in TRMA is absence of a high-affinity thiamine transporter and that low intracellular thiamine concentrations in the mutant cells cause biochemical abnormalities that lead to apoptotic cell death.
Asunto(s)
Anemia Megaloblástica/patología , Apoptosis , Sordera/patología , Diabetes Mellitus/patología , Fibroblastos/patología , Tiamina/farmacología , Anemia Megaloblástica/genética , Anemia Megaloblástica/metabolismo , Apoptosis/efectos de los fármacos , Apoptosis/genética , Proteínas Portadoras/genética , Células Cultivadas , Sordera/genética , Sordera/metabolismo , Diabetes Mellitus/genética , Diabetes Mellitus/metabolismo , Fibroblastos/metabolismo , Humanos , Mutación , Síndrome , Tiamina/genéticaRESUMEN
Thiamine-responsive megaloblastic anemia (TRMA, also known as Rogers syndrome, OMIM 249270) is a rare autosomal recessive disorder characterized by a triad of megaloblastic anemia, diabetes mellitus, and sensorineural deafness. Patients respond, to varying degrees, to treatment with megadoses of thiamine. We have recently shown genetic linkage of the TRMA gene to a 16-centimorgan (cM) region on 1q23.2-1q23.3 based on the analysis of four large, inbred families of Alaskan, Italian, and Israeli-Arab origin. Here we narrow the TRMA interval down to 4 cM based on genetic recombination, homozygosity mapping, and linkage disequilibrium (highest LOD score of 12.5 at D1S2799, at a recombination fraction of 0). We provide further evidence that the TRMA gene is located in this region and confirm the homogeneity of the disease. In this analysis, we genotyped seven additional families of diverse ethnic origin (Pakistani, Indian, Italian, Brazilian, and Japanese), and analyzed additional markers in two previously reported families showing evidence of linkage disequilibrium in a large area of their haplotypes. The multi-system manifestations of TRMA suggest that thiamine has a pivotal role in a multiplicity of physiological processes. Mapping the TRMA gene and understanding the molecular basis of the disease might, thus, shed light on the role of thiamine in common disorders such as deafness, anemia, and diabetes.
Asunto(s)
Anemia Megaloblástica/genética , Mapeo Cromosómico , Cromosomas Humanos Par 1 , Sordera/genética , Tiamina/uso terapéutico , Anemia Megaloblástica/tratamiento farmacológico , Niño , Preescolar , Diabetes Mellitus/genética , Femenino , Haplotipos , Humanos , Lactante , Desequilibrio de Ligamiento , Masculino , SíndromeRESUMEN
BACKGROUND: Leukocyte-endothelial interactions appear to have a important role in ischemia/reperfusion injury and are mediated by specific leukocyte and endothelial adhesion molecules. The selectins are adhesion molecules found on leukocytes (L-selectin) and endothelium (P and E selectin) that bind to oligosaccharide ligands containing fucose and sialic acid to mediate leukocyte rolling on the endothelium. Fucoidin is a nontoxic sulfated fucose oligosaccharide derived from seaweed that blocks the selectins. METHODS: We tested the effects of fucoidin in an isolated blood-perfused neonatal (age range, 3 to 7 days; mean age, 4.3 days) lamb heart model undergoing 2 hours of cold cardioplegic ischemia. In group F (n = 8) fucoidin (30 mg/L) was added at initial reperfusion. Group C (n = 9) received only cardioplegia with no reperfusion intervention. Isovolumic maximum developed pressure and the maximum positive and negative first derivatives of pressure were measured using a catheter-tip transducer in an intraventricular balloon before ischemia and at 30 minutes of reperfusion. Coronary blood flow, myocardial oxygen consumption, and white blood cell counts in the circulating blood were also measured. RESULTS: Percent recoveries of baseline maximum developed pressure and maximum positive and negative first derivatives of pressure in group F (86% +/- 5%, 81% +/- 10%, and 74% +/- 8%, respectively; mean +/- standard deviation) were higher than in group C (77% +/- 5%, 70% +/- 9%, and 65% +/- 6%; p < 0.05). Group F postischemic coronary blood flow was greater (190% +/- 35%) than in group C (102% +/- 10%; p < 0.05). Recovery of myocardial oxygen consumption in group F (86% +/- 14%) was greater than group C (72% +/- 11%; p < 0.05). Postischemic white blood cell count in group F (88% +/- 4%) was greater than in group C (81% +/- 5%; p < 0.05). CONCLUSIONS: Selectin blockade with fucoidin resulted in better recovery of left ventricular function, coronary blood flow, and myocardial oxygen consumption after cold ischemia, despite a higher circulating white blood cell count. These data support the hypothesis that endothelial-leukocyte interactions play an important role in ischemia/reperfusion and suggest that selectin blockade may be a useful therapeutic strategy.