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Query: EC:2.7.10.2 (
focal adhesion kinase
)
44,029
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
Thrombopoietin (TPO), or megakaryocyte growth and development factor (MGDF), has been shown to potentiate the sensitivity of normal human platelets to various agonists in vitro. The present study investigated the functional and biochemical properties of platelets from mice rendered thrombocytopenic by sublethal irradiation with regard to the reactivity to recombinant murine MGDF (rmMGDF) in vitro. During the course of reversible
thrombocytopenia
following irradiation, platelets from irradiated mice which had lower platelet counts and reciprocally higher plasma TPO levels showed lower reactivity to rmMGDF in agonist-induced platelet aggregation. Intravenous injections of recombinant soluble murine c-Mpl (sMpl), which has the ability to capture TPO, after irradiation restored the reactivity of platelets at the platelet nadir to rmMGDF. On the other hand, platelets prepared from normal mice 3 h after a single intravenous injection of pegylated rmMGDF did not respond to rmMGDF. There was a marked decrease in c-Mpl and
Janus kinase 2
(
JAK2
) in platelets from irradiated mice at the platelet nadir. Similar results were observed with platelets from mice administered pegylated rmMGDF.
JAK2
was only moderately decreased, however, in platelets from mice given sMpl after irradiation. These results indicate that exposure of platelets to increased endogenous TPO levels in vivo in thrombocytopenic mice leads to a reduction in the platelet reactivity to rmMGDF in vitro. Further, these results suggest that the c-Mpl-mediated signaling pathway, which is essential for the priming effect of rmMGDF, is defective in thrombocytopenic murine platelets.
...
PMID:Platelets exposed to elevated levels of endogenous thrombopoietin in vivo have a reduced response to megakaryocyte growth and development factor in vitro. 1120 67
Echicetin, a heterodimeric snake C-type lectin from Echis carinatus, is known to bind specifically to platelet glycoprotein (GP)Ib. We now show that, in addition, it agglutinates platelets in plasma and induces platelet signal transduction. The agglutination is caused by binding to a specific protein in plasma. The protein was isolated from plasma and shown to cause platelet agglutination when added to washed platelets in the presence of echicetin. It was identified as immunoglobulin Mkappa (IgMkappa) by peptide sequencing and dot blotting with specific heavy and light chain anti-immunoglobulin reagents. Platelet agglutination by clustering echicetin with IgMkappa induced P-selectin expression and activation of GPIIb/IIIa as well as tyrosine phosphorylation of several signal transduction molecules, including p53/56(
LYN
), p64, p72(
SYK
), p70 to p90, and p120. However, neither ethylenediaminetetraacetic acid nor specific inhibition of GPIIb/IIIa affected platelet agglutination or activation by echicetin. Platelet agglutination and induction of signal transduction could also be produced by cross-linking biotinylated echicetin with avidin. These data indicate that clustering of GPIb alone is sufficient to activate platelets. In vivo, echicetin probably activates platelets rather than inhibits platelet activation, as previously proposed, accounting for the observed induction of
thrombocytopenia
.
...
PMID:Echicetin, a GPIb-binding snake C-type lectin from Echis carinatus, also contains a binding site for IgMkappa responsible for platelet agglutination in plasma and inducing signal transduction. 1129 May 95
This report describes a new low-frequency alloantigen, Oe(a), responsible for a case of neonatal alloimmune
thrombocytopenia
(NAIT). In a population study none of 600 unrelated blood donors was an Oe(a) carrier. By immunochemical studies the Oe(a) antigen could be assigned to platelet glycoprotein (GP) IIIa. Sequencing of GPIIIa complementary DNA from an Oe(a) (+) individual showed deletion of a lysine residue at position 611 (DeltaLys(611)). Analysis of 20 Oe(a) (-) and 3 Oe(a) (+) individuals showed that the DeltaLys(611) form of GPIIIa was related to the phenotype. Anti-Oe(a) reacted with the DeltaLys(611), but not with the wild-type isoforms on stable transfectants expressing GPIIIa, indicating that DeltaLys(611) directly induces the expression of Oe(a) epitopes. Under nonreducing conditions the Pro(33)DeltaLys(611) variant migrated with a slightly decreased molecular weight compared to the Pro(33)Lys(611) isoform suggesting that DeltaLys(611) has an influence on the disulfide bonds of GPIIIa. The Pro(33)DeltaLys(611) GPIIIa could undergo conformational changes and bind to fibrinogen in a similar manner as the Pro(33)Lys(611) isoform. No difference was found in the tyrosine phosphorylation of pp125(
FAK
), suggesting that DeltaLys(611) has no effect on integrin function. In contrast to all other low-frequency antigens, the DeltaLys(611) isoform was associated with the HPA-1b, but not with the high frequency HPA-1a allele. Comparison with GPIIIa DNA from nonhuman primates indicated that the HPA-1a allele represents the ancestral form of GPIIIa. It can be assumed that the Oe(a) form did arise as a result of a mutational event from an already mutated GPIIIa allele.
...
PMID:A functional platelet fibrinogen receptor with a deletion in the cysteine-rich repeat region of the beta(3) integrin: the Oe(a) alloantigen in neonatal alloimmune thrombocytopenia. 1183 Apr 67
A 73-year-old woman with chronic myeloid leukemia was treated with interferon-alpha, hydroxyurea, and busulfan before imatinib mesylate treatment. The leukocyte count was 8,400/; hemoglobin concentration, 12.0 g/; and platelet count, 19.7 x 10(4)/. She received 400 mg of imatinib mesylate for 17 days before the agent was discontinued because of pancytopenia. A bone marrow biopsy on the 87th day after the last imatinib mesylate administration demonstrated severe hypocellularity. She needed many RBC and Plt transfusions and filgrastim administration. Grade 4 neutropenia continued for 35 days and Grade 3
thrombocytopenia
continued for over 122 days. Imatinib mesylate, an agent targeting BCR-
ABL
, is expected to be useful as an effective therapeutic agent for chronic myeloid leukemia. However the present case suggests that its appropriate dose is individually variable and we should carefully consider the former treatment, and the clinical stage of the disease before initiating imatinib treatment.
...
PMID:[Chronic myeloid leukemia associated with sustained severe pancytopenia after imatinib mesylate therapy]. 1241 95
Prior to initiation of the
ARG
-911 and
ARG
-915 clinical trials, there was no optimal replacement for heparin anticoagulation in patients with heparin-induced
thrombocytopenia
(HIT) type II. These prospective, historical controlled studies were designed to determine the usefulness of argatroban, a direct thrombin inhibitor (DTI) that is not immunogenic and does not interact with heparin antibody, in answering this clinical need. Clinical outcomes (37-day period) for 568 argatroban-treated and 193 control patients demonstrated significantly reduced risks of the primary efficacy composite endpoint (all-cause death, all-cause amputation, new thrombosis) and the secondary endpoints (death due to thrombosis, new thrombosis) with argatroban. Argatroban patients also experienced a more rapid recovery of platelet count. Bleeding events were similar among both groups. It was concluded that argatroban anticoagulation, compared with historical controls, improves clinical outcomes without increasing bleeding risk in patients having HIT with or without thrombosis. Argatroban has since been approved in the US for both prophylaxis and treatment of thrombosis in patients with HIT. Argatroban has been used in percutaneous coronary interventions in patients with and without HIT, for peripheral vascular procedures in both large and small vessels in HIT patients, and as an adjunct to thrombolytic therapy for the treatment of AMI. Treatment success rates and the same or less bleeding was demonstrated with argatroban compared to heparin controls. These pilot studies suggest that argatroban will provide reliable anticoagulation during interventional procedures. A consistent safety profile of argatroban has been demonstrated in all studies to date. The main attributes of argatroban are its rapid onset of action, fast reversibility of its anticoagulant effect, inhibition of clot-bound thrombin, easily monitored by the aPTT and ACT and no dosage adjustment in renal-impaired individuals. These properties make argatroban a predictable and useful anticoagulant for HIT and non-HIT patients.
...
PMID:Argatroban in HIT type II and acute coronary syndrome. 1281 Oct 12
Acquired amegakaryocytic
thrombocytopenia
(AATP) in adults is a rare disorder characterized by severe
thrombocytopenia
and decreased or absent megakaryocytes in an otherwise normal bone marrow. We present a 44-yr-old man in whom the diagnosis of AATP was established in January 2001. Immunophenotyping of the peripheral blood lymphocytes showed a relative increase in the subpopulation of gamma/delta T-cell receptor (TCR) positive (gamma/delta TCR(+)) and (CD4, CD8) negative T lymphocytes, and PCR suggested a monoclonal pattern of TCR gamma chain gene rearrangement. Cytogenetic examination of his bone marrow cells showed a normal male karyotype but RT-PCR analysis revealed a BCR-
ABL
(p210) fusion transcript. The inhibition of CFU-Mk growth mediated by the patient's T lymphocytes indicated that the pathogenic mechanism for AATP could be an immunological attack on megakaryocyte progenitors where the gamma/delta TCR-positive T lymphocytes are directly involved. The case emphasizes the complex association of T-lymphocyte monoclonal proliferation and AATP.
...
PMID:Acquired amegakaryocytic thrombocytopenia associated with proliferation of gamma/delta TCR T-lymphocytes and a BCR-ABL (p210) fusion transcript. 1545 17
Imatinib mesylate is a relatively new drug that targets the BCR-
ABL
chimeric protein, the molecular basis of chronic myeloid leukemia (CML). A phase II clinical trial in 39 Japanese patients in the first chronic phase of CML was conducted with imatinib mesylate at a dose of 400 mg/day. Hematologic complete response was obtained in 92.3% of the patients, complete cytogenetic response (CR) was obtained in 43.6%, and major partial CR was obtained in 20.5% of the patients. Although 29 of 39 patients required an adjustment of dosing because of grade 3 or 4 adverse events, most of the events were reversible, and 25 of the 29 patients were able to resume therapy. Between day 15 and day 35, grade 3 or 4 neutropenia and/or leukocytopenia occurred in 13 patients, and grade 3
thrombocytopenia
occurred in 5 patients. Overall, nonhematologic grade 3 adverse events occurred in 28.2% of the patients. These data support the use of imatinib mesylate as the treatment of choice for chronic-phase CML patients.
...
PMID:Efficacy and safety of imatinib mesylate for patients in the first chronic phase of chronic myeloid leukemia: results of a Japanese phase II clinical study. 1554 Sep 2
Chronic myeloid leukemia (CML) is a hematopoietic stem cell disorder characterized by the balanced reciprocal translocation t (9:22). The resulting fusion gene, the BCR-
ABL
, is responsible for oncogenesis. Imatinib mesylate is a novel molecule, which inhibits the protein product of this fusion gene and hence has been used in the treatment of CML. The present study evaluates 174 patients with CML treated with imatinib mesylate. Of these 174 patients, 97 were in chronic phase, 47 in accelerated phase and 30 patients had blast crisis. Patients in chronic phase received imatinib mesylate in the dose of 400-mg daily, while those in accelerated phase and blast crisis received 600 to 800 mg daily. Of the 97 patients with chronic phase, 49 patients (50.5%) achieved a major (major + complete) cytogenetic response. Of the 47 patients in accelerated phase, 10 patients (21.3%) achieved a major cytogenetic response and in 30 patients with blast crisis, 7 (23.3%) achieved a major cytogenetic response. Dermatitis, mucositis, neutropenia and
thrombocytopenia
were some of the major toxicities. Of interest, 121 of the 174 patients (69.5%) developed generalized hypopigmentation. We conclude that imatinib mesylate is a safe and effective first-line therapy for chronic myeloid leukemia.
...
PMID:Imatinib mesylate in chronic myeloid leukemia: a prospective, single arm, non-randomized study. 1598 13
The present phase II study aimed to define the application of a novel regimen incorporating methotrexate, paclitaxel, epirubicin, and carboplatin (M-TEC) in advanced bladder cancer, essentially as an M-VAC-like regimen, by substitution of cisplatin by carboplatin, doxorubicin by epirubicin and vinblastine by paclitaxel. Forty patients with advanced bladder cancer entered the study; 34 males/6 females, median age: 68 (range, 59-76), median PS (Karnovsky): 80, without receiving prior chemotherapy. Disease extention was as follows; 11/40 had local recurrence, 6/40 liver metastases, 14/40 lung metastases, bone and lymph node 8/40, bones-lymph node-lung metastases 4, lymph node and liver 4/40, lymph node-liver and lung metastases 2/40. Drug schedule and doses were as follows: paclitaxel 180 mg/m2, carboplatin AUC = 5 (according to creatinine clearance, based on Calvert's formula), and epirubicin 40 mg/m2 were administered during day 1, whereas methotrexate 30 mg/m2 and epirubicin 40 mg/m2 were administered on day 14. All patients were evaluable for response with 24/40 responding [response rate (RR) 60%]; 10/40 (25%) CR, 14/40 (35%) PR, 9/40 (22.5%) SD, and 7/40 (17.5%) PD. Symptomatic improvement was observed in 50% of patients. The median duration of response was 22 (14-32) weeks, median time-to-progression (TTP) 33 (12-44) weeks, and median survival was 56 (20-84) weeks. Toxicity was well accepted and was mainly neutropenia > grade 3: 17%, anemia >grade 3: 16%,
thrombocytopenia
> grade 2: 6%, nausea & vomiting mainly > grade 2: 31%, according to the administered chemotherapy cycles, whereas fatigue grade 2-3: 19%, neurotoxicity grade 1-2 13% of patients, and alopecia grade 2 was observed in all patients. The present pilot study indicates the feasibility of the M-
TEC
combination for bladder cancer with acceptable toxicity.
...
PMID:Methotrexate-paclitaxel-epirubicin-carboplatin (M-TEC) combination chemotherapy in patients with advanced bladder cancer: an open label phase II study. 1616 25
We report on a patient fulfilling the diagnostic criteria of unclassifiable myelodysplastic/myeloproliferative diseases with prominent erythropoietic hyperplasia/dysplasia (erythroid preleukemia) and the unique translocation (8;9)(p23;p24). The patient presented with B-symptoms, erythroblastemia,
thrombopenia
, marked eosinophilia, presence of myeloid precursors in the peripheral blood, and decreased erythropoietin level. Nodular peritrabecular polymorphous blasts, dysplastic megakaryocytes, and a diffuse argyrophilic fibrosis were detected in the trephine bone marrow biopsy. Immunohistochemically, the blasts stained positively for glycophorin C and hemoglobin A; the proliferation fraction was nearly 90% in the Ki-67 stain. Expression of the phosphorylated
Janus kinase 2
was detected in almost all megakaryocytes and in isolated erythroblast islets, suggesting a probable activation of
Janus kinase 2
, the jak-2 gene being mapped on 9p24. Ten months after initial diagnosis, the disease progressed to frank acute erythroid leukemia. We report for the first time a myelodysplastic/myeloproliferative disease (erythroid preleukemia) accompanied by the specific chromosomal aberration t(8;9)(p23;p24), distinct histopathology, and clinical and laboratory symptoms, and progress to acute erythroid leukemia.
...
PMID:Myelodysplastic/myeloproliferative disease with erythropoietic hyperplasia (erythroid preleukemia) and the unique translocation (8;9)(p23;p24): first description of a case. 1656 30
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