Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.11.1.8 (thyroid peroxidase)
3,116 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To clarify the regulatory mechanism of thrombopoietin (TPO, c-Mpl ligand) in chronic thrombocytopenic conditions, we determined TPO levels in the sera of patients with aplastic anaemia (AA; n = 26) and idiopathic thrombocytopenic purpura (ITP; n = 32) by an enzyme-linked immunosorbent assay. Despite a similarity in platelet counts, serum TPO levels in the AA group were markedly higher than those in the ITP group: 20.41 +/- 9.71 f mol/ml (mean +/- SD) and 1.66 +/- 0.55 f mol/ml, respectively, both of which were significantly elevated compared to normal subjects (n = 41; 1.22 +/- 0.37). In both groups, serum TPO level showed an inverse correlation with the platelet count. We determined the megakaryocyte volume using bone marrow clot section and found that it was markedly small in the AA group; while in the ITP group it was augmented with a correlation to serum TPO level. Our findings suggest that TPO levels may be regulated not only by platelets but also megakaryocytes in AA and ITP.
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PMID:Regulation of serum thrombopoietin levels by platelets and megakaryocytes in patients with aplastic anaemia and idiopathic thrombocytopenic purpura. 886 22

To evaluate the diagnostic value of thrombopoietin (TPO, c-mpl ligand) measurements, and clarify the regulatory mechanisms of TPO in normal and in thrombocytopenic conditions, the plasma TPO concentration was determined in normal individuals (n = 20), umbilical cord blood (n = 40), chronic idiopathic thrombocytopenic purpura (ITP; n = 16), in severe aplastic anaemia (SAA; n = 3), chemotherapy-induced bone marrow hypoplasia (n = 10), myelodysplastic syndrome (MDS; n = 11), and sequentially during peripheral blood progenitor cell transplantation (n = 7). A commercially available ELISA and EDTA-plasma samples were used for the analysis. The plasma TPO concentration in the normals and umbilical cord blood were 52 +/- 12 pg/ml and 66 +/- 12 pg/ml, respectively. The corresponding values in patients with SAA and chemotherapy-induced bone marrow hypoplasia were 1514 +/- 336 pg/ml and 1950 +/- 1684 pg/ml, respectively, and the TPO concentration, measured sequentially after myeloablative chemotherapy and peripheral blood progenitor cell transplantation, was inversely related to the platelet count. In contrast, the plasma TPO recorded in patients with ITP (64 +/- 20 pg/ml) and MDS (68 +/- 23 pg/ml) were only slightly higher than normal levels. In conclusion, TPO levels were significantly elevated in patients in which bone marrow megakaryocytes and platelets in circulation were markedly reduced, whereas TPO levels were normal in ITP patients, and only slightly increased in the MDS patients. These latter patients displayed a preserved number of megakaryocytes in bone marrow biopsies. Our data support the suggestion that megakaryocyte mass affects the plasma TPO concentration. In thrombocytopenic patients a substantially increased plasma TPO implies deficient megakaryocyte numbers. However, TPO measurements do not distinguish between ITP and thrombocytopenia due to dysmegakaryopoiesis, as seen in MDS patients.
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PMID:Plasma thrombopoietin levels in thrombocytopenic states: implication for a regulatory role of bone marrow megakaryocytes. 963 81

A 45-year-old women with chronic idiopathic thrombocytopenic purpura was given monthly injections of the GnRH agonist leuprolide acetate for the treatment of uterine leiomyoma. Two weeks after the fifth injection, she showed mild symptoms of thyrotoxicosis. At that time, serum thyroxin (T4) and triiodothyronine (T3) levels were elevated whereas TSH level was suppressed. Anti-thyroglobulin (anti-Tg) and anti-thyroid peroxidase (anti-TPO) antibodies were positive, whereas TSH binding inhibitory immunoglobulin (TBII) was undetectable. Two months later, serum T4 and T3 levels spontaneously decreased below the normal ranges. Five months after the onset of the disease, they returned to normal without any treatment. Anti-TPO and anti-Tg antibodies gradually decreased during the clinical course. Thus, the present case was indicated to be an instance wherein silent thyroiditis developed after leuprolide acetate administration. This is the first report to demonstrate the association of thyroid disorder with leuprolide injection.
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PMID:Transient thyrotoxicosis and hypothyroidism following administration of the GnRH agonist leuprolide acetate. 1122 54

The association of immune dysfunction in patients with human immunodeficiency virus (HIV) infection and AIDS and the development of autoimmune diseases is intriguing. Yet, the spectrum of reported autoimmune phenomena in these patients is increasing. An infectious trigger for immune activation is one of the postulated mechanisms and derives from molecular mimicry. During frank loss of immunocompetence, autoimmune diseases that are predominantly T cell subtype CD8 driven predominate. There is evidence for B cell stimulation and many autoantibodies are reported in HIV patients. We propose a staging of autoimmune manifestations related to HIV/AIDS manifestations and the total CD4 count and viral load that may be beneficial in identifying the type of autoimmune disease and establishing the proper therapy. In stage I there is the acute HIV infection, and the immune system is intact. In this stage, autoimmune diseases may develop. Stage II describes the quiescent period without overt manifestations of AIDS. However, there is a declining CD4 count indicative of some immunosuppression. Autoimmune diseases are not found. During stage III there is immunosuppression with a low CD4 count and the development of AIDS. CD8 T cells predominant and diseases such as psoriasis and diffuse immune lymphocytic syndrome (similar to Sjogren's syndrome) may present or even be the initial manifestation of AIDS. Also during this stage no autoimmune diseases are found. In stage IV there is restoration of immune competence following highly active anti-retroviral therapy (HAART). In this setting, there is a resurgence of autoimmune diseases. The frequency of reported rheumatological syndromes in HIV-infected patients ranges from 1 to 60%. The list of reported autoimmune diseases in HIV/AIDS include systemic lupus erythematosus, anti-phospholipid syndrome, vasculitis, primary biliary cirrhosis, polymyosits, Graves' disease, and idiopathic thrombocytopenic purpura. Also, there is an array of autoantibodies reported in HIV/AIDS patients which include anti-cardiolipin, anti-beta2 GPI, anti-DNA, anti-small nuclear ribonucleoproteins (snRNP), anti-thyroglobulin, anti-thyroid peroxidase, anti-myosin, and anti-erythropoietin antibodies. The association of autoantibodies in HIV-infected patients to clinical autoimmune disease is yet to be established. With the upsurge of HAART, the incidence of autoimmune diseases in HIV-infected patients is increasing. In this review, we describe the various autoimmune diseases that develop in HIV/AIDS patients through possible mechanisms related to immune activation.
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PMID:HIV and autoimmunity. 1284 88

Idiopathic thrombocytopenic purpura (ITP) is a common hematological disease. It bleeds with peripheral blood platelet reduction as the main clinical manifestation, and manifests a chronic history in adult people. 11% - 35% ITP patients develop into a refractory course, which may be related with gene polymorphisms. There is currently no consensus on how best to manage refractory/relapsed ITP. In part, this reflects the need for individualized treatment due to the patients' requirements and their responsiveness to therapies. The objective of this review is to provide a clinically useful guide to current management strategies. This article summarizes all the treatment for refractory ITP, and highlights new therapies, including the anti-CD20 antibody, thrombopoietic agents, TPO receptor agonist and HSCT. The pancytoprotector shows good effect in the treatment of refractory and relapsed ITP in China. In a word, to give different treatments individually is most important.
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PMID:[Individualizing treatment of refractory and relapsed ITP in adults and its development of study]. 2003 Sep 58

The current concepts and the management of ITP have significantly changed in the past decade. Decreased use of cytotoxic therapy and the introduction of new selective modalities of drug such as TPO-r mimetics are the landmarks of this change. Discovered in the middle of last decade, followed by experiments in mice and then approved in humans, Eltrombopag is the first TPO-r mimetic available. It has been used and validated in several clinical studies in different etiologies of thrombocytopenia, including primary ITP (chronic Immune ThrombocytoPenia) and secondary ITP, due to hepatitis C and more recently in bone marrow failure as myelodysplastic syndromes. Good tolerability and low side effects are the strengths of this drug, contrasted with issues regarding administration (it must be taken every day apart from specific meals containing high levels of calcium, which leads to problems with compliance). We review the first clinical studies with this agent, emphasizing the significant findings.
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PMID:Eltrombopag. 2105 63

In the 16 years since thrombopoietin was identified and cloned, much has been learned about its biochemistry, how it is regulated, and its involvement in a wide range of functions in a variety of cell lineages. The first generation of recombinant human thrombopoietins, rHuTPO and pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF), were shown to increase platelet counts in patients with immune thrombocytopenia, in platelet apheresis donors, and in patients receiving nonmyeloablative chemotherapy. Their effects in patients with acute myeloid leukemia (AML) showed no benefit at a wide range of doses and schedules. The two second-generation TPO mimetics approved by the US Food and Drug Administration (FDA) for the treatment of ITP, romiplostim and eltrombopag, are now being studied in a number of thrombocytopenic disorders including those due to chemotherapy and hepatitis C. Since romiplostim is comparable to the first-generation recombinant thrombopoietins, it may not be beneficial in AML treatment; however, given its novel mechanism of action, eltrombopag may be a TPO potentiator and if given at the proper time during chemotherapy, may enable AML patients to recover platelet counts sooner.
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PMID:What is the potential for thrombopoietic agents in acute leukemia? 2212 20

We present a case of slowly progressive gait ataxia with a 16-year history in an 87-year-old woman. In 1994 she became aware of a slight unsteadiness while walking and cortical cerebellar atrophy was diagnosed. She had no familial history of neurological disorders. In 2007, idiopathic thrombocytopenic purpura (ITP) was diagnosed. The symptoms gradually worsened, and she was admitted in 2010 because she could not walk without support. MRI voxel-based morphometry (VBM) imaging showed atrophy of the entire cerebellum, and SPECT using eZIS showed reduced perfusion in the same regions. Her blood was positive for both anti-TPO antibody (42 IU/ml) and anti-gliadin antibody (20.2 EU). We therefore diagnosed autoimmune cerebellar atrophy. The patient showed a positive response to intravenous immunoglobulins (IVIg) and regained the ability to walk unassisted. Her posture and gait disturbance scores on the International Cooperative Ataxia Rating Scale had improved from 20 to 9. Even 16 years after onset, intravenous immunoglobulins were effective. In cases of prolonged disease, immunotherapy can be effective in autoimmune cerebellar atrophy and should not be excluded from the treatment choices.
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PMID:[Case of anti-TPO/gliadin antibody-positive cerebellar atrophy that responded to intravenous immunoglobulin therapy begun 16 years after onset]. 2268 15

Primary immune thrombocytopenia, or idiopathic thrombocytopenic purpura (ITP), is an autoimmune disorder characterized by isolated thrombocytopenia due to accelerated platelet destruction and impaired platelet production. Autoantibodies against platelet surface glycoproteins, such as GPIIb/IIIa and GPIb/IX complexes, play major roles in both platelet destruction and impaired platelet production, although autoantibody-independent mechanisms, such as T cell-mediated cytotoxicity, may also be involved in its pathogenesis. Recent advances in the localization of autoantigenic epitopes and the characterization of T cell functional abnormalities in ITP patients have improved our understanding of the pathophysiology of this disease. Although corticosteroids and splenectomy remain central to the treatment of ITP, a new class of drugs, i.e., thrombopoietin receptor agonists (TPO-RAs) and rituximab, have substantially broadened the therapeutic options for refractory ITP patients. Moreover, the success of TPO-RAs in ITP patients shows that reduced platelet production caused by impaired megakaryocytopoiesis plays a greater role in ITP than previously recognized.
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PMID:Pathophysiology and management of primary immune thrombocytopenia. 2370 14

We report two patients (70- and 49-year-old Japanese men) with acute exacerbation of chronic idiopathic thrombocytopenic purpura (ITP) and deep venous thrombosis of the lower extremities. Both were successfully managed with thrombopoietin receptor agonist (TPO-RA) administration. Both had ITP refractory to steroid treatment. Their immature platelet fraction (absolute-IPF) counts were increased and paralleled the platelet recoveries after TPO-RA (eltrombopag and romiplostim, respectively) without progression of thrombosis. Although ITP has recently been evaluated as a thrombophilic disorder, reports on acute exacerbation of ITP with newly diagnosed thrombosis are limited, and the pathophysiology and association between ITP and thrombosis remain to be elucidated. Moreover, the influences of TPO-RA on thrombosis are still controversial. To our knowledge, this is the first case report describing patients with exacerbation of ITP who developed thrombosis and were treated with TPO-RA. The outcomes of our cases underscore the importance of monitoring thrombosis and not delaying the initiation of anticoagulation treatment during the use of TPO-RA.
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PMID:[Thrombopoietin receptor agonists administration for acute exacerbation of chronic idiopathic thrombocytopenic purpura and subsequent anticoagulant therapy for accompanying deep venous thrombosis of the lower limbs]. 2497 40


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