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

---

Query: EC:3.5.1.1 (asparaginase)
2,695 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new protocol for the stabilization of the quaternary structure of multimeric enzymes has been attempted using as model enzyme (tetrameric) L-asparaginase from Escherichia coli. Such strategy is based upon multisubunit covalent immobilization of the enzyme onto activated supports (agarose-glutaraldehyde). Supports activated with different densities of reactive groups were used; the higher the density of groups, the higher the stabilization attained. However, because of the complexity of that enzyme, even the use of the highest densities of reactive groups was not enough to encompass all four subunits in the immobilization process. Therefore, a further chemical intersubunit cross-linking with aldehyde-dextran was pursued; these derivatives displayed a fully stabilized multimeric structure. In fact, boiling the modified enzyme derivative in the presence of sodium dodecyl sulfate and beta-mercaptoethanol did not lead to release of any enzyme subunit into the medium. Such a derivative, prepared under optimal conditions, retained ca. 40% of the intrinsic activity of the free enzyme and was also functionally stabilized, with thermostabilization enhancements of ca. 3 orders of magnitude when compared with its soluble counterpart. This type of derivative may be appropriate for extracorporeal devices in the clinical treatment of acute leukemia and might thus bring about inherent advantages in that all subunits are covalently bound to the support, with a longer half-life and a virtually nil risk of subunit release into the circulating blood stream.
...
PMID:Structural and functional stabilization of L-asparaginase via multisubunit immobilization onto highly activated supports. 1138 76

Among 511 patients with therapy-related myelodysplastic syndrome or acute leukemia (t-MDS/t-AL) and balanced chromosome aberrations, 162 (32%) had translocations involving 11q23. The recurring translocation partners were 9p22 (48%), 19p13.3 (11%), 19p13.1 (10%), 4q21 (9%), 6q27 (6%), 1p32 (2%), 16p13.1 (2%), 10p13 (1%), and 17q25 (1%); in 9%, the translocations were seen only once. The remaining 349 patients were divided into five subgroups based on the balanced aberration: 21q22, inv(16), t(15;17), Rare, and Unique aberrations. Patients in the 11q23 subgroup had a sole cytogenetic abnormality more often than those in the 21q22, inv(16), Rare, and Unique subgroups, and a complex karyotype or -5/del(5q) and/or -7/del(7q) less often than patients in the 21q22, Rare, and Unique subgroups. Clinically, 11q23 patients had acute lymphoblastic leukemia (ALL) more often as their primary disease and a shorter latency from start of treatment for the primary disease to their t-MDS/t-AL diagnosis, except when compared with the inv(16) subgroup. The 11q23 subgroup demonstrated a younger age at t-MDS/t-AL diagnosis, but this finding was not significant when patients with AL as their primary diagnosis were excluded. Survival from the time of diagnosis of t-MDS/t-AL was significantly shorter for the 11q23 subgroup compared with that of the 21q22, inv(16), and t(15;17) subgroups (median 8 vs. 14, 28, and 29 months, respectively). Inferior survival occurred even though 11q23 patients were younger and more often received blood or marrow transplantation (BMT). Even among patients receiving BMT, 11q23 patients had a shorter median survival (9 vs. 12-31 months for the other subgroups). However, among 11q23 patients, those receiving BMT survived longer, with 1- and 5-year survivals of 43% and 18% compared with 23% and 7% for patients not transplanted. With regard to prior therapy, 11q23 patients, compared with other patients, received radiotherapy less often as their sole therapy and chemotherapy more often. They had received VP16, methotrexate, 6MP/6TG, L-asparaginase, daunorubicin, cytarabine, and VM26 more often, likely attributed to the high frequency of AL as their primary disease. More patients in the 11q23 subgroup had received doxorubicin, except in comparison with the 21q22 subgroup; more vincristine, except in comparison with the Rare and Unique subgroups; and more prednisone, except in comparison with the Unique subgroup. Patients in the 11q23 subgroup more often received alkylating agents (AAs) (86% vs. 59-82% for the other subgroups), and topoisomerase II inhibitors (TIs) (84% vs. 49-75%), and they more often reported exposure to AAs plus TIs without radiotherapy (33% vs. 12-21%), except in comparison with the 21q22 subgroup (36%). We performed a multivariate analysis to determine whether the adverse survival of 11q23 patients compared to other Workshop patients was explained by factors other than the presence of the 11q23 abnormality. Covariates in the final model were the five cytogenetic subgroup indicators, where the 11q23 subgroup was the referent (P < 0.0001); age at t-MDS/t-AL (P = 0.0036); previous exposure to lomustine (P < 0.0001) and mitoxantrone (P = 0.0225); BMT for t-MDS/t-AL (P = 0.0006); and karyotype complexity (P = 0.0114). The risk of death for 11q23 patients relative to patients in the 21q22, inv(16), t(15;17), and Unique subgroups was significant, even after adjustment for other risk factors (relative risks 2.3, 3.6, 3.1, and 1.5, respectively; P < 0.0001 for the first three comparisons and P = 0.0125 for the last). When a multivariable model was constructed, excluding patients with AL or MDS as their primary diagnosis, the relative risk of death for 11q23 patients was significantly higher than that of all five other cytogenetic subgroups. We conclude that among t-MDS/t-AL patients with balanced aberrations, 11q23 translocations are an independent adverse risk factor. Although BMT is the current therapy of choice, new treatment is required.
...
PMID:11q23 balanced chromosome aberrations in treatment-related myelodysplastic syndromes and acute leukemia: report from an international workshop. 1192 Dec 71

A 2-year-old Japanese boy who presented with multiple cervical, axillary, and inguinal lymphadenopathy was diagnosed by immunocytochemical analysis as having myeloid/natural killer (NK) cell precursor acute leukemia. Leukemic blasts in the bone marrow were positive for CD56 (NK marker), CD7 (T-cell marker), CD33 (myeloid marker), CD34, and HLA-DR. Tumor cells in a lymph node were also positive for CD2, cytoplasmic CD3 (T-cell marker), CD7, CD33, CD34, and CD56, but negative for peroxidase staining and other T-cell, NK, and myeloid markers. Southern blot analysis showed no rearrangement bands for T-cell receptor delta and immunoglobulin heavy chain. Chromosomal analysis revealed 46,XY,inv(7)(p21q21). Neither chemotherapy for acute lymphoblastic leukemia nor that for acute myeloid leukemia induced remission in this patient. However, complete remission was achieved by the administration of L-asparaginase (6,000 U/m2 for 5 days). Because the disease was considered refractory to standard chemotherapy, cord blood transplantation was performed from an HLA 1-locus mis-matched unrelated donor. The conditioning regimen consisted of total body irradiation, cytarabine, and cyclophosphamide, and cyclosporine and short-term methotrexate were employed for graft-versus-host disease (GVHD) prophylaxis. Hematological reconstitution was rapid, and only grade I acute GVHD was observed. The patient has been in remission for more than 24 months after transplantation. Our findings indicate that combination therapy with L-asparaginase and allogeneic stem cell transplantation may be useful for the treatment of myeloid/NK cell precursor acute leukemia.
...
PMID:Treatment of a child with myeloid/NK cell precursor acute leukemia with L-asparaginase and unrelated cord blood transplantation. 1193 70

Glufosfamide is a new agent for cancer chemotherapy. The objective of the study was the comparison of the in vitro drug resistance profile of glufosfamide with other oxazaphosphorines in 106 samples of childhood acute leukemia by means of the MTT assay. The following drugs were tested: glufosfamide, 4-HOO-ifosfamide, 4-HOO-cyclophosphamide, mafosfamide cyclohexylamine salt, prednisolone, vincristine, L-asparaginase, daunorubicin and cytarabine. In the group of initial Acute Lymphoblastic Leukemia (ALL) samples, equivalent cytotoxicity values for glufosfamide, 4-HOO-ifosfamide, 4-HOO-cyclophosphamide and mafosfamide were 5.95, 9.92, 4.60 and 3.90 microg/ml, respectively. In comparison to initial ALL samples, the relative resistance for glufosfamide and 4-HOO-ifosfamide in relapsed ALL samples were 1.9 (p=0.049) and 1.3 (ns), and in initial Acute Myeloblastic Leukemia (AML) samples, respectively, 31 (p<0.001) and 5 (p=0.001). All oxazaphosphorines showed highly significant cross-resistance. In conclusion, in vitro activity of glufosfamide is comparable to ifosfamide. Glufosfamide shows high activity against lymphoblasts both on diagnosis and on relapse, however it cannot circumvent resistance to other oxazaphosphorines.
...
PMID:In vitro activity of glufosfamide in childhood acute leukemia. 1201 97

We report 2 children with acute leukemia who developed symptomatic cholelithiasis and choledocholithiasis shortly after receiving sequential high-dose cytarabine and asparaginase. Known risk factors for gallstone formation were not present in our patients. These children did not experience any unusual therapy-related hepatic toxicity after laparoscopic cholecystectomy.
...
PMID:Cholelithiasis and choledocholithiasis after sequential cytarabine and asparaginase. 1290 18

Acute leukemias tend to affect a younger population and are much more common in pregnant patients than chronic leukemias are. We report a case of acute lymphoblastic leukemia diagnosed during the third trimester presenting with organomegaly and thrombocytopenia. Delivery of the fetus by cesarean section was decided because of the fulminant nature of the acute leukemia within days of admission. Bone marrow biopsy revealed acute lymphocytic leukemia, French American-British L2 subtype B cell immunotype. A left ovarian mass was identified during the cesarean section which later proved to be lymphoblastic infiltration. The patient was started on induction chemotherapy consisting of vincristine, daunorubicin, prednisolone, and l-asparaginase immediately after the diagnosis. The patient died of Acinetobacter septicemia 18 days after the first admission.
...
PMID:Acute leukemia in pregnancy with ovarian metastasis: a case report and review of the literature. 1467 33

Drug sensitivity of tumor cells was studied in 154 children diagnosed with acute leukemia. Cellular sensitivity in acute lymphoblastic leukemia (ALL) was higher than in acute myeloid one (AML), while T-line ALL cells were more sensitive to dexamethasone than those of B-line. It was suggested that lower drug sensitivity of ALL cells at the earlier stages of cell differentiation was due to their reduced susceptibility to apoptosis. Among AML cells, M3 variant was less sensitive to cytozar while M4 - to vepeside. Reduced sensitivity to vincristine was found in series M3 > M1 - M2 > M4 while that to L-asparaginase was in M1- M2 > M4 > M3.
...
PMID:[Drug sensitivity of tumor cells in varieties of acute childhood leukemia]. 1675 10

A 46-year-old male with refractory biphenotypic acute leukemia was treated with doxorubicin (days 1-3, 15-17), vincristine (days 1, 8, 15, 22), prednisolone (days 1-28), and L-asparaginase (L-ASP: days 15-28) as reinduction therapy. Physical examination revealed normotensive state and normal consciousness. On the 27th day, systemic seizures developed with mild hypertension (BP 151/98 mmHg). Computed tomography (CT) imaging of the brain showed areas of hypodensity in the bilateral white matter, and in the occipital and posterior parietal areas. Fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) showed some high intensity area involving the white matter, but also involving the cortex in the same area. Because the patient's condition progressed into unconsciousness and apnea from recurrent seizures, a respirator and anticonvulsants were needed. Four days later, the patient's general condition dramatically improved. There were no abnormal findings on MRI, and we diagnosed the cause of the seizures as reversible posterior leukoencephalopathy syndrome (RPLS). In adults, RPLS caused by chemotherapy is rare, especially L-ASP. Our patient did not have any previous history of convulsion up to the LAdVP, which brought on the seizures. It was considered that the RPLS might be caused by L-ASP, which had been given to this patient for the first time and was being given to him at the time of developing the seizures. RPLS is one of the causes of neurologic complications by L-ASP.
...
PMID:[Reversible posterior leukoencephalopathy syndrome probably caused by L-asparaginase]. 1686 82

Resistance to chemotherapy is an obstacle to the successful treatment of oncohematological malignances. Failure of therapeutic treatment may be due to the development of multidrug resistance (MDR), the mechanisms of which include upregulation of membrane-resident transporters that efflux chemotherapeutic drugs from tumor cells. Deregulation may occur at different levels: gene or protein expression or function depletion. Childhood acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) cells and chronic lymphocytic leukemia (CLL) cells of adults were studied. ABCB1 (P-gp) and ABCG2 (BCRP) expression were determined by flow cytometry, rhodamine 123 (Rho123) and mitoxantrone were used for functional activity study of MDR proteins, sensitization of leukemic cells to drugs was quantified by methyl thiazolyl tetrazolium (MTT) assays. Appropriate gene expression was determined using semi-quantitative RT-PCR. No differences between expression of P-gp and BCRP and genes in primary and relapsed acute leukemia (AL) cells as well as in de novo and treated CLL samples were established. Higher expression of P-gp and BCRP proteins was detected in CLL lymphocytes compared to blast cells. Increased P-gp protein expression and function was detected in cells of CLL patients who had more aggressive therapy regimen. Doxorubicine, rubomycinum and L-asparaginase resistance correlates with P-gp overexpression and increased function in pediatric AL whereas vincristine resistance might be associated with P-gp protein expression in AL samples and impared P-gp function in CLL lymphocytes only. A tendency for the decreased doxorubicin cytotoxic activity was shown in BCRP-overexpressing cells both in children and adults leukemia. Multifactorial ANOVA showed that P-gp/MDR1 and BCRP as well as their function could not be used as unconditional and universal predictors of leukemia cell drug resistance in vitro. These results suggest that studied MDR transporter-proteins have a limited role per se in vitro and admittedly in vivo drug resistance estimated in leukemia patients or it is not yet fully understood unless would not be studied in aggregate. In any event, the expression and function studies of the proteins under investigation when singularly considered do not have a crucial significance for impact on drug resistance evaluation in all leukemia patients.
...
PMID:ABCB1 and ABCG2 proteins, their functional activity and gene expression in concert with drug sensitivity of leukemia cells. 1963 83

From 1984 to 2001, the Pediatric Oncology Group (POG) conducted 12 acute lymphoblastic leukemia (ALL) studies. Ten-year event-free survival (EFS) for patients >12 months of age with B-precursor ALL on acute leukemia in children 14, 15 and 16 series were 66.7+/-1.2%, 68.1+/-1.4% and 73.2+/-2.1%, respectively. Intermediate dose methotrexate (ID MTX; 1 g/m(2)) improved outcomes for standard risk patients (10-year EFS 77.5+/-2.7% vs 66.3+/-3.1% for oral MTX). Neither MTX intensification (2.5 g/m(2)) nor addition of cytosine arabinoside/daunomycin/teniposide improved outcomes for higher risk patients. Intermediate dose mercaptopurine (1 g/m(2)) failed to improve outcomes for either group. Ten-year EFS for patients with T-cell ALL, POG 8704 and 9404 were 49.1+/-3.1% and 72.2+/-4.7%, respectively. Intensive asparaginase (10-year EFS 61.8 vs 42.7%) and high-dose MTX (5 g/m(2)) (10-year EFS 78.0 vs 65.8%) improved outcomes. There was a non-significant improvement in EFS for infants (10-year EFS 17.7+/-7.2-31.9+/-8.3%). Prognostic indicators for B-precursor ALL were age and WBC at diagnosis, gender, central nervous system disease, DNA index and cytogenetic abnormalities. Only gender was prognostic in T-cell ALL. In infants, WBC and MLL translocation were linked to inferior outcome.
...
PMID:Long-term results of the pediatric oncology group studies for childhood acute lymphoblastic leukemia 1984-2001: a report from the children's oncology group. 2001 27


<< Previous 1 2 3 4 5 6 7 Next >>

---