The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Yuan Xu - One of the best experts on this subject based on the ideXlab platform.
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generic matrix evaluation of sv40 clearance by anion exchange chromatography in flow through mode
Biotechnology and Bioengineering, 2003Co-Authors: Sherrie Curtis, Gregory S. Blank, Kurt Brorson, Yuan XuAbstract:The potential of viral contamination is a regulatory concern for Continuous Cell Line-derived pharmaceutical proteins. Complementary and redundant safety steps, including an evaluation of the viral clearance capacity of unit operations in the purification process, are performed prior to registration and marketing of biotechnology pharmaceuticals. Because process refinement is frequently beneficial, CBER/FDA has published guidance facilitating process improvement by deLineating specific instances where the bracketing and generic approaches are appropriate for virus removal validation. In this study, a generic/matrix study was performed using Q-Sepharose Fast Flow (QSFF) chromatography to determine if bracketing and generic validation can be applied to anion exchange chromatography. Key operational parameters were varied to upper and lower extreme values and the impact on viral clearance was assessed using simian virus 40 (SV40) as the model virus. Operational ranges for key chromatography parameters were identified where an SV40 log10 reduction value (LRV) of ≥4.7 log10 is consistently achieved. On the basis of the apparent robustness of SV40 removal by Q-anion exchange chromatography, we propose that the concept of “bracketed generic” validation can be applied to this and potentially other chromatography unit operations. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 179–186, 2003.
Robert B. Tesh - One of the best experts on this subject based on the ideXlab platform.
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In vitro cultivation of Wolbachia pipientis in an Aedes albopictus Cell Line.
Insect molecular biology, 1997Co-Authors: Scott Leslie O'neill, M Pettigrew, Steven Sinkins, Henk R. Braig, Theodore G. Andreadis, Robert B. TeshAbstract:A Continuous Cell Line, Aa23, was established from eggs of a strain of the Asian tiger mosquito, Aedes albopictus, naturally infected with the intraCellular symbiont Wolbachia pipientis. The resulting Cell Line was shown to be persistently infected with the bacterial endosymbiont. Treatment with antibiotics cured the Cells of the infection. In the course of establishing this Cell Line it was noticed that RFLPs in the PCR products of two Wolbachia genes from the parental mosquitoes were fixed in the infected Cell Line. This indicates that the mosquito host was naturally superinfected with different Wolbachia strains, whereas the infected Cell Line derived from these mosquitoes only contained one of the original Wolbachia strains. The development of anin vitroculture system for this fastidious microorganism should facilitate molecular analysis of the reproduction distorting phenotypes it induces in natural arthropod hosts.
Armando Patrizio - One of the best experts on this subject based on the ideXlab platform.
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vandetanib has antineoplastic activity in anaplastic thyroid cancer in vitro and in vivo
Oncology Reports, 2018Co-Authors: Silvia Martina Ferrari, Guido Bocci, Teresa Di Desidero, Ilaria Ruffilli, Giusy Elia, Francesca Ragusa, Anna Fioravanti, Paola Orlandi, Sabrina Rosaria Paparo, Armando PatrizioAbstract:The antitumor activity of vandetanib [a multiple signal transduction inhibitor including the RET tyrosine kinase, epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF) receptor (VEGFR), ERK and with antiangiogenic activity], in primary anaplastic thyroid cancer (ATC) Cells, in the human Cell Line 8305C [undifferentiated thyroid cancer (TC)] and in an ATC‑Cell Line (AF), was investigated in the present study. Vandetanib (1 and 100 nM; 1, 10, 25 and 50 µM) was tested by WST‑1, apoptosis, migration and invasion assays: in primary ATC Cells, in the 8305C Continuous Cell Line, and in AF Cells; and in 8305C Cells in CD nu/nu mice. Vandetanib significantly reduced ATC Cell proliferation (P<0.01, ANOVA), induced apoptosis dose‑dependently (P<0.001, ANOVA), and inhibited migration (P<0.01) and invasion (P<0.001). Furthermore, vandetanib inhibited EGFR, AKT and ERK1/2 phosphorylation and downregulated cyclin D1 in ATC Cells. In 8305C and AF Cells, vandetanib significantly inhibited the proliferation, inducing also apoptosis. 8305C Cells were injected subcutaneously in CD nu/nu mice and tumor masses became detectable after 30 days. Vandetanib (25 mg/kg/day) significantly inhibited tumor growth and VEGF‑A expression and microvessel density in 8305C tumor tissues. In conclusion, the antitumor and antiangiogenic activity of vandetanib is very auspicious in ATC, opening the way to a future clinical evaluation.
I L Sargent - One of the best experts on this subject based on the ideXlab platform.
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ed27 trophoblast like Cells isolated from first trimester chorionic villi are genetically identical to hela Cells yet exhibit a distinct phenotype
Placenta, 2002Co-Authors: Douglas A Kniss, Y Xie, Sailesh Kumar, E A Linton, P Cohen, P Fanhavard, C W G Redman, I L SargentAbstract:Abstract ED 27 trophoblast-like Cells were prepared from human chorionic villus samples obtained at 9 weeks gestation and have been grown Continuously in vitro without phenotypic drift for nearly a decade. These Cells express many trophoblast markers, including cytokeratin, placental alkaLine phosphatase (PLAP), secretion of 17β-estradiol, and a microvillous apical surface. The ED 27 Cell Line is a useful model system for studies of placental Cell biology and has been distributed to laboratories world-wide. However, experiments to investigate their relationship to primary villous cytotrophoblast have shown that these Cells do not secrete detectable amounts of human chorionic gonadotropin in culture and, when digested with trypsin, disperse into individual Cells. Furthermore, immunocytochemical studies demonstrated that, unlike villous cytotrophoblasts, ED 27 Cells were immunoreactive with monoclonal antibodies recognizing some HLA Class I antigens. This was not HLA-G, however, as would be expected if these Cells originated from extravillous cytotrophoblasts, but rather classical HLA-A, B which is thought not to be expressed by any trophoblast subpopulations. These inconsistencies prompted us to question the authenticity of the Continuous Cell Line as it now exists. Genetic haplotype analysis using the polymerase chain reaction (PCR) revealed that ED 27 was genetically identically to the HeLa Cell Line. Inasmuch as HeLa Cells have never been grown in the laboratory (DAK), the only possible origin of HeLa Cell contamination of ED 27 Cells was the WISH Cell Line, and further PCR analysis revealed that this Cell Line was also genetically identical to HeLa. Like ED 27 Cells, HeLa Cells and WISH Cells synthesized small amounts of estrogen and were found to express PLAP and antigens recognized by the monoclonal antibodies ED822, directed against the syncytiotrophoblast, and J1B5 directed against villous cytotrophoblast. These results point out the need for adherence to rigorous and consistent quality control measures to assure the authenticity of Cell Lines used as in vitro model systems.
Douglas A Kniss - One of the best experts on this subject based on the ideXlab platform.
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ed27 trophoblast like Cells isolated from first trimester chorionic villi are genetically identical to hela Cells yet exhibit a distinct phenotype
Placenta, 2002Co-Authors: Douglas A Kniss, Y Xie, Sailesh Kumar, E A Linton, P Cohen, P Fanhavard, C W G Redman, I L SargentAbstract:Abstract ED 27 trophoblast-like Cells were prepared from human chorionic villus samples obtained at 9 weeks gestation and have been grown Continuously in vitro without phenotypic drift for nearly a decade. These Cells express many trophoblast markers, including cytokeratin, placental alkaLine phosphatase (PLAP), secretion of 17β-estradiol, and a microvillous apical surface. The ED 27 Cell Line is a useful model system for studies of placental Cell biology and has been distributed to laboratories world-wide. However, experiments to investigate their relationship to primary villous cytotrophoblast have shown that these Cells do not secrete detectable amounts of human chorionic gonadotropin in culture and, when digested with trypsin, disperse into individual Cells. Furthermore, immunocytochemical studies demonstrated that, unlike villous cytotrophoblasts, ED 27 Cells were immunoreactive with monoclonal antibodies recognizing some HLA Class I antigens. This was not HLA-G, however, as would be expected if these Cells originated from extravillous cytotrophoblasts, but rather classical HLA-A, B which is thought not to be expressed by any trophoblast subpopulations. These inconsistencies prompted us to question the authenticity of the Continuous Cell Line as it now exists. Genetic haplotype analysis using the polymerase chain reaction (PCR) revealed that ED 27 was genetically identically to the HeLa Cell Line. Inasmuch as HeLa Cells have never been grown in the laboratory (DAK), the only possible origin of HeLa Cell contamination of ED 27 Cells was the WISH Cell Line, and further PCR analysis revealed that this Cell Line was also genetically identical to HeLa. Like ED 27 Cells, HeLa Cells and WISH Cells synthesized small amounts of estrogen and were found to express PLAP and antigens recognized by the monoclonal antibodies ED822, directed against the syncytiotrophoblast, and J1B5 directed against villous cytotrophoblast. These results point out the need for adherence to rigorous and consistent quality control measures to assure the authenticity of Cell Lines used as in vitro model systems.
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insulinlike growth factors their regulation of glucose and amino acid transport in placental trophoblasts isolated from first trimester chorionic villi
Journal of Reproductive Medicine, 1994Co-Authors: Douglas A Kniss, Phillip J Shubert, Peter D Zimmerman, Mark B Landon, Steven G GabbeAbstract:The transport of glucose and amino acids from the maternal to fetal circulation through the placenta is critical to the delivery of fuel for normal fetal growth and development. Little information indicates that transplacental glucose or amino acid transport is influenced by hormones or polypeptide growth factors. We developed a Continuous Cell Line of cytotrophoblastlike Cells derived from first-trimester human chorionic villi as a model system to study the regulation of glucose and amino acid transport by insulinlike growth factors (IGFs). Using immunocytochemical and biochemical criteria, the Cells were shown to manifest a trophoblastlike phenotype. The Cells were maintained in serum-supplemented medium until confluent, at which time they were shifted to serum-free medium for one day. Experiments were initiated by transferring the Cells to glucose-free assay buffer and incubating them with IGF-I, IGF-II or insulin. Glucose uptake was measured by the transport of 2-deoxy-D-[1,2-3H]glucose (2[3H]DG) in the presence or absence of cytochalasin B, which has been shown to competitively inhibit glucose uptake. IGF-I, IGF-II and insulin each enhanced 2[3H]DG transport in a dose-dependent fashion. Amino acid transport was measured by incubation of the Cells with IGF-I for 60 minutes, followed by a 5-minute challenge with alpha-[methyl-3H]aminoisobutyric acid. IGF-I caused a dose-dependent increase in uptake of the amino acid analog. Radioreceptor assays using [125I]insulinlike growth factor I ([125I]IGF-I) demonstrated that the trophoblast-derived Cells contained high-affinity, saturable receptors for IGF-I that also bound IGF-II.(ABSTRACT TRUNCATED AT 250 WORDS)