Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0019829 (Hodgkin's disease)
 30,247 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Voltage-clamp of excitable membrane allows the measurement of membrane currents associated with electrical potential changes across the membrane. However, it has been impossible in practice to apply the conventional analog feedback voltage-clamp circuits to single electrode voltage clamping in central neurons. The reason for this is that the feedback system becomes unstable because of the positive feedback required for compensation of capacitative loss through the wall of the microelectrode. Park et al. (1981) proposed a new iterative technique to solve this problem. It requires that the potential to be clamped repeats itself with little or no change. The amount of current needed to clamp the membrane potential is not determined at once, but in a step-wise, trial and error fashion in the course of a set of repetitions. Since the feedback loop is open in real time, the system has great stability, and this advantage can be exploited in single electrode preparations. The computation algorithm which calculates the current waveform based on the voltage deviation during the last trial is the central part of the iterative voltage-clamp system. In this paper, we propose a new algorithm, which has several theoretical and practical advantages over the original one proposed by Park et al. First, two parameters used in the new algorithm are predetermined by a current-clamp experiment. Second, the speed of convergence of the new algorithm is faster than that of the Park's original algorithm. This was shown by computer simulation of iterative voltage clamp of artificial membrane following Hodgkin-Huxley equations for squid axon membrane and Rall's compartment model for a neuron with dendrites. Finally, we offer proof that the new algorithm is certain to converge for the general cases of voltage-clamp experiments with active membrane properties, synaptic membranes, etc. Consequently, the new algorithm for iterative voltage clamp is very suitable for single electrode voltage clamp in the central neurons. The new algorithm has been successfully applied to voltage-clamp experiments on rubrospinal neurons of cats (Tsukahara, Murakami, Kawato, Oda, and Etoh, in preparation).
 ...
PMID:A new algorithm for voltage clamp by iteration: a learning control of a nonlinear neuronal system. 407 70

The receptor for human interleukin-9 (hIL-9) might be a target for selective immunotherapy. It is expressed on a variety of malignant cells, including Hodgkin's lymphoma, non-Hodgkin lymphoma and acute myeloid leukemia (AML). We therefore constructed a new chimeric toxin by fusing hIL-9-cDNA to modified Pseudomonas aeruginosa exotoxin A (ETA'). The binding properties of the new recombinant protein, rhIL-9-ETA', were assessed on different cell lines expressing the hIL-9 receptor. The antitumor potency of rhIL-9-ETA' was evaluated against the Hodgkin-derived cell lines L540Cy, KM-H2 and L1236, the Burkitt lymphoma cell line Daudi, the erythroleukemia cell line K562, and the mastocytoma cell line P815-hIL9R, transfected with hIL-9 receptor cDNA. Recombinant hIL-9-ETA' exhibited potent specific cytotoxic effects against P815-hIL9R, K562 and L1236 cells, inhibiting protein synthesis by 50% (IC50) at concentrations of 0.05, 0.58 and 3 micrograms/ml respectively. The cytotoxic effect was abrogated after addition of polyclonal antibodies against the human IL-9. rhIL-9-ETA' might be of potential use against hIL-9R-expressing malignancies.
 ...
PMID:A deletion mutant of Pseudomonas exotoxin-A fused to recombinant human interleukin-9 (rhIL-9-ETA') shows specific cytotoxicity against IL-9-receptor-expressing cell lines. 938 98

The data of a closed phase I/II trial in patients with resistant Hodgkin's lymphoma indicate promising results using a chemically linked anti-CD25 ricin-A immunotoxin (IT) (RFT5-SMPT-dgA). This IT is based on the high-affinity moab RFT5. Since recombinant DNA technology permits the readier production of large amounts of ITs, we constructed a new RFT5-based fusion toxin [RFT5(scFv)-ETA']. We isolated mRNA from the hybridoma cell line RFT5, synthesized first strand cDNA and performed RT-PCR. Amplified coding regions of the light and heavy chain variable domains were joined together with a synthetic (Gly4-Ser)3 linker. The resulting single chain variable fragment (scFv) was fused to a modified Pseudomonas aeruginosa exotoxin A (ETA') lacking its cell-binding domain I. After IPTG-induced expression in Escherichia coli, the 70 kDa His-tagged fusion protein [RFT5(scFv)-ETA'] was isolated by osmotic shock and sonication under denaturing conditions. The recombinant toxin was purified on a Ni2+-NTA chelating sepharose and eluted with 250 mM imidazole. Pooled protein was renatured, dialyzed and concentrated by precipitation. Binding properties of RFT5(scFv)-ETA' were assessed on the CD25-expressing cell line L540cy by ELISA, immunohistochemistry and FACS analysis. CD25-specific binding was confirmed by immunoprecipitation experiments with recombinant human IL-2 receptor alpha. The in vitro toxicity of the chimeric protein was tested on the Hodgkin-derived cell lines L540cy, L428, L1236, a monocyte cell line U937 and a Burkitt lymphoma cell line BL38. RFT5(scFv)-ETA' inhibited protein biosynthesis of L540cy and L428 cells by 50% at concentrations (IC50) of 18 and 12 ng/ml, respectively. CD25-specific toxicity was confirmed by competitive toxicity assays. These data confirm for the first time binding specificity and toxicity of a recombinant anti-CD25 immunotoxin, against Hodgkin-derived cell lines; its applicability on Hodgkin's lymphoma needs yet to be evaluated in vivo.
 ...
PMID:Construction and in vitro evaluation of RFT5(scFv)-ETA', a new recombinant single-chain immunotoxin with specific cytotoxicity toward CD25+ Hodgkin-derived cell lines. 985 27

The human CD30 receptor is highly overexpressed on the surface of Hodgkin Reed-Sternberg cells and has been shown to be an excellent target for selective immunotherapy using monoclonal antibody-based agents such as immunotoxins. To construct a new recombinant immunotoxin for possible clinical use in patients with Hodgkin's lymphoma, we have chosen the murine anti-CD30 hybridoma Ki-4 to generate a high-affinity Ki-4 single-chain variable fragment (scFv). Hybridoma V-genes were polymerase chain reaction-amplified, assembled, cloned and expressed as a mini-library for display on filamentous phage. Functional Ki-4 scFv were obtained by selection of binding phage on the Hodgkin lymphoma-derived, CD30-expressing cell line L540Cy. The selected recombinant Ki-4 scFv was shown to specifically bind to an overlapping epitope on the CD30 antigen with binding kinetics similar to those of the original antibody. The Ki-4 scFv was subsequently fused to a deletion mutant of Pseudomonas exotoxin A (ETA'). The resulting immunotoxin Ki-4(scFv)-ETA' specifically binds to CD30+ L540Cy cells and inhibits the protein synthesis by 50% at a concentration (IC50) of 43 pM. This recombinant immunotoxin is a promising candidate for further clinical evaluation in patients with Hodgkin's lymphoma or other CD30+ malignancies.
 ...
PMID:An anti-CD30 single-chain Fv selected by phage display and fused to Pseudomonas exotoxin A (Ki-4(scFv)-ETA') is a potent immunotoxin against a Hodgkin-derived cell line. 1037 74

Recombinant DNA technology makes it possible to genetically fuse V genes or cytokines to toxin domains, resulting in immunotherapeutics for selective destruction of tumor cells. Since recombinant immunotoxins can be easily manipulated in terms of affinity or cytotoxic potency and produced in large quantities, we have developed a new CD30 ligand-based fusion toxin (CD30L-ETA'). Human CD30L cDNA was ligated into a pET-based expression plasmid and thereby fused to a modified Pseudomonas aeruginosa exotoxin A (ETA') lacking its cell-binding domain I. After IPTG-indiced expression in E. coli strain BL21(DE3), the 60 kDa His-tagged fusion protein (CD30L-ETA') was isolated from inclusion bodies. Denatured protein was renatured in the presence of 0.4 M arginine and a glutathione redox system. Refolded protein was purified and concentrated by ion-exchange chromatography on a HiTrap Q column. The binding properties of CD30L-ETA' were evaluated by competitive ELISA, immunohistochemical staining, and FACS analysis on CD30-expressing cells. The in vitro toxicity of the fusion protein was then tested on the CD30+ Hodgkin-derived cell line L540cy and the Burkitt's lymphoma cell line BL38. CD30L-ETA' exhibited specific cytotoxicity against L540cy cells (IC50 = 24 ng/ml) as determined by [3H]leucine uptake assays. This is the first report on the specificity and cytotoxic potency of a chimeric CD30L fusion toxin against Hodgkin's disease-derived cells.
 ...
PMID:CD30L-ETA': a new recombinant immunotoxin based on the CD30 ligand for possible use against human lymphoma. 1051 79

Since clinical phase-I/II trials in patients with resistant Hodgkin's lymphoma treated with the chemically linked anti-CD25 ricin-A-chain immunotoxin RFT5-SMPT-dgA indicate promising results for patients with minimal residual disease, we constructed a new immunotoxin by fusing the RFT5 single-chain variable fragment to a deletion mutant of Pseudomonas exotoxin A (ETA'). The recombinant protein was directed into the periplasmic space of E. coli by means of the pET-derived expression vector pBM1.1 and our newly developed expression/purification method. Biologically active RFT5(scFv)-ETA' was isolated by freezing/thawing and purified by immobilized metal-ion affinity and molecular-size-chromatography. RFT5(scFv)-ETA' was subsequently used for the treatment of disseminated human Hodgkin's lymphoma in a SCID-mouse model. The mean survival time (MST) of L540rec-challenged SCID mice was 38.1 days. A single i.v. injection of 40 microg recombinant immunotoxin (rIT) 1 day after tumor inoculation resulted in 100% tumor-free mice, extending the MST to more than 220 days (p < 0.0001). The blood-distribution time T(1/2)alpha was 39.65 min, the serum elimination time T(1/2)alpha, 756.6 min. All animals were assessed for soluble interleukin-2 receptor alpha, which is directly correlated to tumor burden. Soluble CD25 was not detectable in mice treated with the rIT. Our findings, concerning potent anti-tumor effects of a recombinant anti-CD25 immunotoxin against disseminated Hodgkin's lymphoma in SCID mice reported here demonstrate that RFT5(scFv)-ETA' might be suitable for further evaluation against Hodgkin's lymphoma in humans.
 ...
PMID:Recombinant anti-CD25 immunotoxin RFT5(SCFV)-ETA' demonstrates successful elimination of disseminated human Hodgkin lymphoma in SCID mice. 1079 96

The human lymphocyte activation marker CD30 is highly overexpressed on Hodgkin/Reed-Sternberg cells and represents an ideal target for selective immunotherapy. We used the murine anti-CD30 hybridoma Ki-4 to construct a new recombinant immunotoxin (rIT) for possible clinical use in patients with CD30(+) lymphoma. Hybridoma V genes were polymerase chain reaction-amplified, assembled, cloned, and expressed as a mini-library for display on filamentous phage. Functional Ki-4 scFv obtained by selection of binding phage on the CD30-expressing Hodgkin lymphoma cell line L540cy was inserted into the bacterial expression vector pBM1.1 and fused to a deletion mutant of Pseudomonas exotoxin A (ETA'). Periplasmically expressed Ki-4(scFv)-ETA' demonstrated specific activity against a variety of CD30(+) lymphoma cells as assessed by different in vitro assays. To evaluate in vivo antitumor activity, severe combined immunodeficient mice challenged with human lymphoma cell lines were treated with the immunotoxin. The blood distribution time t(1/2)alpha of Ki-4(scFv)-ETA' was 19 minutes, and its serum elimination time t(1/2)alpha was 193 minutes. A single intravenous injection of 40 microg rIT 1 day after tumor inoculation rendered 90% of the mice tumor free, extending the mean survival time to more than 200 days compared with 38.1 days in the phosphate-buffered saline control group (P <.001). This new rIT is a promising candidate for further clinical evaluation in patients with Hodgkin lymphoma or other CD30(+) malignancies. (Blood. 2000;95:3909-3914)
 ...
PMID:Ki-4(scFv)-ETA', a new recombinant anti-CD30 immunotoxin with highly specific cytotoxic activity against disseminated Hodgkin tumors in SCID mice. 1084 27

In recent years, substantial experience has been accumulated with tumor-specific immunotherapeutics which seem to be effective against minimal residual disease. The coupling of toxins to monoclonal antibodies has indicated promising results in early clinical trials. Recombinant DNA technology makes it possible to genetically fuse coding regions of V genes or cytokines to modified toxin domains. These recombinant immunotoxins can easily be manipulated to increase the cytotoxic potency or affinity. Binding single-chain variable fragments (scFv) expressed as chimeric fusion proteins on the surface of filamentous bacteriophages were selected on Hodgkin-derived cell lines. This technique was also used to create a new humanized anti-CD30 scFv which exhibits similar binding to the CD30 antigen when compared to its murine predecessor. ScFvs were then inserted into a new bacterial expression vector and thus fused to a deletion mutant of Pseudomonas exotoxin. Anti-CD25(scFv)-ETA' and anti-CD30(scFv)-ETA' were isolated from E. coli periplasm and purified by metal chelate affinity and size exclusion chromatography. All immunotoxins produced showed specific cytotoxicity against Hodgkin lymphoma cell lines as documented by competitive assays. In addition, these constructs were highly efficient in the treatment of disseminated human Hodgkin's disease in SCID mice. These in vivo data indicate a possible clinical impact for patients with relapsed CD25- and/or CD30-positive lymphoma.
 ...
PMID:Recombinant immunotoxins for the treatment of Hodgkin's disease (Review). 1102 15

Since the disialoganglioside GD2 is abundantly present on the surface of neuroblastoma cells, we constructed a new recombinant immunotoxin for possible clinical use in patients with neuroblastoma. A functional 14.18 scFv-phage was obtained by selection of an anti-GD2 hybridoma derived phage antibody mini-library on the neuroblastoma-derived, GD2-expressing cell line IMR5. By insertion into the bacterial expression vector pBM1.1 the selected scFv was fused to a deletion mutant of Pseudomonas exotoxin A (ETA'). Periplasmically expressed 14.18(scFv)-ETA' bound to the GD2 expressing cell line IMR5, but not to the GD2 negative Hodgkin-derived cell line L540Cy as documented by ELISA and flow cytometry. The recombinant immunotoxin (rIT) inhibited cell viability of IMR5 cells by 50% at concentrations (IC(50)) of 0.326 microg/ml. This recombinant immunotoxin will be further investigated in vivo for its value as a new immunotherapeutic agent for the treatment of patients with neuroblastoma.
 ...
PMID:An anti-GD2 single chain Fv selected by phage display and fused to Pseudomonas exotoxin A develops specific cytotoxic activity against neuroblastoma derived cell lines. 1160 31

There is increasing evidence that the shedding of extracellular antigen domains impedes selective immunotherapy. One example is CD30, which is overexpressed on the surface of malignant lymphoma cells and has been identified as a promising target for antibody-based immunotherapy. However, CD30 is cleaved from the surface of target cells and the resulting soluble ectodomain (sCD30) is protecting the cells from antibody binding. Shedding can be inhibited by hydroxamate inhibitors of metalloproteinases such as BB-3644. We thus evaluated the influence of BB-3644 on the efficacy of the anti-CD30 single-chain immunotoxin Ki-3(scFv)-ETA'. In vitro, the addition of BB-3644 augmented the antitumor effect of Ki-3(scFv)-ETA' against Hodgkin-derived L540Cy cells by a factor of 2.75. Severe combined immunodeficiency (SCID) mice challenged with CD30-positive L540Cy cells were treated with the immunotoxin. One single nontoxic dose of BB-3644 increased the mean survival time of animals treated concomitantly with Ki-3(scFv)-ETA' to 93 days as compared with 35 days in the control (p = 0.0017). When BB-3644 was continuously delivered using subcutaneously implanted pumps, this effect was even more pronounced with no observed tumor growth in the animals within 200 days. Thus, concomitant application of metalloproteinase inhibitors might become clinically relevant in antibody-based immunotherapy against targets known to be shed from tumor cells.
 ...
PMID:Metalloproteinase inhibition augments antitumor efficacy of the anti-CD30 immunotoxin Ki-3(scFv)-ETA' against human lymphomas in vivo. 1523 35


1 2 Next >>