Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002874 (aplastic anemia)
 5,905 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Growth of the patients with hematological malignancies, aplastic anemia, Fanconi's anemia, and Wiscott-Aldrich syndrome who had been treated with bone marrow transplantation (BMT) was studied. Fourteen out of 21 patients showed suppression of linear growth after BMT. Recovery of the growth velocity after 1-2 years tended to occur if BMT was performed at younger age. Six of eight patients with chronic graft-versus-host-disease (CGVHD) had impaired growth after BMT, whereas eight of 13 (61%) without CGVHD did. Provocative tests for growth hormone (GH) performed 5-72 months after BMT revealed three boys who showed poor response to more than two different stimuli. Two of these three boys had prolonged suppression of growth. Neither the age at BMT, difference in disease, nor presence of posttransplant growth retardation gave significant difference in the response of GH to provocative tests. It was concluded that approximately two-thirds of marrow-grafted children experienced transient decrease in growth velocity after BMT.
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PMID:Growth after bone marrow transplantation in children. 179 50

In 1967 the first patient in Northern Ireland commenced growth hormone treatment for short stature. By the end of December 1988 a total of 89 patients had been treated. Thirty-two had idiopathic isolated growth hormone deficiency, an incidence of 1.5 new cases per year (in a population of 1.5 million with approximately 30,000 births per year). Since 1967 the mean age at starting treatment has fallen from 18 years to 10 years and the height standard deviation score has fallen from -4.7 +/- 0.6 to -3.4 +/- 0.3. The group with classical growth hormone deficiency (maximum GH less than 7 mU/l during insulin-induced hypoglycaemia) had a greater increase in height velocity over the first year of treatment, 3.8 +/- 0.4 cm, than those with a partial deficiency (maximum growth hormone 7.1 - 20 mU/l), 1.9 +/- 0.4 cm. All pre-pubertal children responded with a rise in the height velocity standard deviation score from -1.8 +/- 0.3 before treatment to +3.5 +/- 0.4 over the first year of treatment. 58% of the adult males and 25% of adult females have attained an adult height within the normal range (3rd centile or above). There have been three deaths, one each from Fanconi's aplastic anaemia which predated growth hormone treatment, an accidental fire injury and a relapsing craniopharyngioma. There have been no deaths from Creutzfeldt-Jakob disease. Growth hormone therapy is safe and effective, but continues to be commenced late in terms both of age and height standard deviation score.
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PMID:The Northern Ireland experience of growth hormone therapy for short stature. 260 65

Growth and growth hormone (GH) were investigated every year in 24 children after allogeneic bone marrow transplantation (BMT) for severe aplastic anemia (SAA) or leukemia. Conditioning included total body irradiation (TBI) in all cases of leukemia. The young leukemic children grew poorly. At 4 years after BMT, the mean standard deviation score for attained height had decreased from 0 to -1.73. GH deficiency was diagnosed with provocation tests. Three years after BMT, 10/18 children had a subnormal response. Ten children were further investigated with 24-hour GH profiles. Children with SAA had normal growth and GH levels. TBI seemed to be the major factor responsible for impaired growth.
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PMID:Growth and growth hormone in children after bone marrow transplantation. 307 33

Few data are available on the long-term effect of bone marrow transplantation (BMT) on growth. This study examines those factors that play a role in the final height outcome of patients who underwent BMT during childhood. Data on 181 of 230 patients with aplastic anemia, leukemias, and lymphomas who had BMT before puberty (mean age, 9.8 +/- 2.6 years) and who had reached their final height were analyzed. An overall decrease in final height standard deviation score (SDS) value was found compared with the height at BMT (P < 10(7)) and with the genetic height (P < 10(7)). Girls did better than boys, and the younger in age the person was at time of BMT, the greater the loss in height. Previous cranial irradiation + single-dose total body irradiation (TBI) caused the greatest negative effect on final height achievement (P < 10(4)). Fractionation of TBI reduces this effect significantly and conditioning with busulfan and cyclophosphamide seems to eliminate it. The type of transplantation, graft-versus-host disease, growth hormone, or steroid treatment did not influence final height. Irradiation, male gender and young age at BMT were found to be major factors for long-term height loss. Nevertheless, the majority of patients (140/181) have reached adult height within the normal range of the general population.
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PMID:Final height of patients who underwent bone marrow transplantation for hematological disorders during childhood: a study by the Working Party for Late Effects-EBMT. 1036 Nov 7

ERYTHROPOIETIN (EPO): Erythropoietin (EPO) is a hormone that promotes the proliferation and differentiation of erythroid progenitor cells and regulates the number of erythrocytes in peripheral blood. EPO is produced mainly by the kidneys, and transcription of the EPO gene is promoted by a reduction in the oxygen concentration in the blood. The existence of EPO was suggested near the end of the 19th century by the discovery that hypoxia increases the production of red blood cells. EPO was identified as a serum factor in the 1950s, and in 1970 Miyake and coworkers succeeded in purifying it by using the urine of patients with aplastic anemia as a starting material. The human EPO gene was cloned in 1985 using a partial amino acid sequence from this purified EPO, and it is well known that recombinant EPO is currently used as a drug to treat anemia associated with chronic renal failure and other illnesses. ACTION OF EPO: When human bone marrow cells are cultured in a semisolid medium containing EPO, they form small erythroblast colonies in five to seven days, and by day 10 large erythroblast colonies appear that resemble fireworks ("burst" colonies). The original cells in the former colonies are called colony forming units-erythroid (CFU-E) or late-stage erythroblast progenitor cells and in the latter colonies they are called burst forming units-erythroid (BFU-E) or early-stage erythroblast progenitor cells. As shown in Figure 1, red blood cells are produced through differentiation from stem cells to BFU-E, CFU-E, and erythroblasts. Although EPO acts on both BFU-E and CFU-E cells, CFU-E cells show greater sensitivity to EPO, and other factors such as stem cell factor (SCF), interleukin (IL)-3, IL-4, and granulocyte macrophage colony-stimulating factor (GM-CSF) must be present together with EPO for BFU-E cell proliferation. In erythroblasts beyond the CFU-E stage, sensitivity to EPO decreases as the cells mature. THE EPO RECEPTOR AND THE CYTOKINE RECEPTOR FAMILY: The EPO receptor gene was cloned by D'Andrea and coworkers in 1989 from murine erythroleukemia cells [1]. It became clear that the EPO receptor belongs to the cytokine receptor family that comprises receptors for the various interleukins, GM-CSF, granulocyte colony-stimulating factor (G-CSF), growth hormone and prolactin. The special characteristic of this family of receptors is that they are switched on (i.e., the receptor is activated) and transduce signals to the interior of the cell by the formation of homo- or hetero-oligomers (dimers or trimers). Moreover, hetero-oligomers of these receptors share a common receptor subunit. As shown in Figure 2, the IL-3, IL-5 and GM-CSF receptors have a common &bgr; subunit, and their ligand specificity is determined by the &agr; subunit. In the same manner, the IL-6, LIF and oncostatin M (OSM) receptors all share gp130, which is the &bgr; subunit of the IL-6 receptor. The IL-2, IL-4 and IL-7 receptors all share the &ggr; subunit of the IL-2 receptor. All the above receptors are activated by the formation of hetero-oligomers, but the G-CSF receptor, EPO receptor, and growth hormone receptor are activated by the formation of homodimers of the same types of molecules [2]. We can see that groups of cytokines such as the interleukins that affect a relatively wide range of cells and have redundant biological activity create this redundancy through the common use of a single receptor subunit. On the other hand, EPO and G-CSF act with high specificity on a relatively limited range of cells, so it was probably unnecessary for their receptors to share one of the subunits. EPO RECEPTOR AND JAK2 KINASE: The signal for cellular proliferation and differentiation into erythroblasts is thought to originate at the EPO receptor. The cytoplasmic domain of the EPO receptor can be divided into two major regions. Roughly half of the cytoplasmic domain, the part lying nearest the plasma membrane, is required for generating the signals for proliferation and differentiation such as the induction of globin synthesis [3, 4]. The remaining half is not required for this signaling, and, conversely, it acts to dampen the signals. It is known that a tyrosine kinase called JAK2 associates with the region near the plasma membrane, undergoes autophosphorylation, and phosphorylates the EPO receptor, and a transcription factor called a STAT [5]. It is thought that JAK2 plays an important role in promoting cellular proliferation. The STAT is activated by the phosphorylation, and it then translocates to the nucleus, recognizes a specific base sequence in the promoter region of its target gene, and initiates transcription. At present, we know that the STAT whose activation is mediated by the EPO receptor is STAT5, and the target genes are CIS [6], which has an SH2 domain (a molecular structure that recognizes a phosphorylated tyrosine) and OSM [7], which is a pleiotropic cytokine. However, activation of STAT5 and activation of the target genes are not unique to the EPO receptor, and they also occur with the IL-2 and IL-3 receptors. Moreover, the JAK2 substrate that is directly linked to cellular proliferation is still unknown. At present, studies are under way to determine the transcription factors specific to EPO and their target genes, as well as the substrates of JAK2. RECEPTOR PHOSPHORYLATION AND CESSATION OF THE SIGNAL: On the other hand, tyrosine phosphorylation of the receptor is necessary at the cytoplasmic tail region far from the plasma membrane, and the signal transduction pathway that originates with this phosphorylated tyrosine and is mediated by proteins with SH2 domains becomes activated. First, a GTP/GDP exchange factor called SOS, which is mediated by Shc and Grb2, migrates to the plasma membrane and converts a ras protein to its GTP form. The activated ras protein then activates the Raf-MAP kinase kinase-MAP kinase cascade, and ultimately initiates the transcription of oncogenes such as c-fos and c-jun. An enzyme called PI3 kinase binds to the tyrosine phosphorylation site of the receptor and a second messenger is born. It is known that this pathway is a requirement for DNA synthesis in certain types of fibroblasts. However, these signal transduction pathways are not unique to the EPO receptor, and they are also activated by most growth factor receptors, so they are not necessarily required for EPO-induced proliferation. Conversely, the tyrosine phosphatase SH-PTP1 (also called HCP) that has an SH2 domain and is specific to blood cells associates with the tyrosine phosphorylation site of the receptor and promotes the dephosphorylation of JAK2. In other words, the role of SH-PTP1 is to stop generation of the signal [8]. Therefore, in mutations lacking this cytoplasmic tail region of the receptor far from the plasma membrane, the receptors do not undergo tyrosine phosphorylation, JAK2 activation continues for a longer period of time, and thus the signal is generated more efficiently. In fact, in one patient with a mild case of familial erythrocytosis a mutation was discovered in which the C-terminus of the EPO receptor was missing 70 amino acids [9]. This was a dominant genetic trait, and the patient's erythroblasts showed an increased sensitivity to EPO. In this family the impairment was not severe enough to be called an illness, and in fact it is said that this patient was proficient enough athletically to compete for a gold medal at the Olympics. More specifically, the reason that athletes undergo training at high altitudes is to boost EPO production because of the lower oxygen partial pressure, and this brings about the desired effect of sustained athletic capability due to a resultant increase in red blood cells. However, the same effect has occurred naturally in this athlete thanks to accelerated receptor capability.
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PMID:Physician Education: The Erythropoietin Receptor and Signal Transduction. 1038 12

We report a 12-year-old girl with aplastic anemia accompanied by chromosome 8 trisomy during growth hormone (GH) therapy. When she was six years old she was diagnosed as idiopathic isolated GH deficiency, and GH therapy (0.175 mg/kg/week) was initiated. At the age 12, she began to exhibit petechiae in both lower limbs. Platelet count was 11,000/microL; serum hemoglobin level 11.8 gr/mL; white blood cell count 3,400/microL, with 37% neutrophils, 58% lymphocytes, 4% monocytes and 1% basophils. Bone marrow examination showed that total nucleated cell count and megakaryocyte were 17,000/microL and 0/microL, respectively, suggesting low formation. In addition, 13% of bone marrow cells contained the 3 signals of chromosome 8 marker (trisomy 8). She was diagnosed as aplastic anemia accompanied with chromosome 8 trisomy. GH therapy was stopped immediately, and simultaneous administration of methylprednisolone and anti-thymocyte globulin was initiated. Platelet count improved with treatment, and the 3-signal chromosome 8 abnormality disappeared from the bone marrow cells. The fact that a hematological adverse effect other than leukemia exists in conjunction with GH therapy warrants further investigation into possible hematological changes occurring during or after GH therapy.
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PMID:Aplastic anemia during growth hormone (GH) treatment in a girl with idiopathic GH-deficiency. 1459 22