Millipore Sigma Vibrant Logo
 

Diethylene


167 Results Búsqueda avanzada  
Mostrar
Productos (90)
Documentos (74)
Páginas (3)

Acote sus resultados Utilice los filtros siguientes para refinar su búsqueda

Tipo de documento

  • (67)
  • (6)
  • (1)
¿No encuentra lo que está buscando?
Póngase en contacto con
el Servicio de Atención
al Cliente

 
¿Necesita ayuda para encontrar un documento?

  • Inactivation of HNSCC cells by 90Y-labeled cetuximab strictly depends on the number of induced DNA double-strand breaks. 23345302

    Radioimmunotherapy is considered to have great potential for efficient and highly specific treatment of tumors. The aim of this study was to determine the efficacy of radioimmunotherapy when using (90)Y-labeled cetuximab and to determine to what degree induction and repair of DNA double-strand breaks (DSBs) are decisive for this approach.This study was performed with 9 cell lines of squamous cell carcinoma of the head and neck (HNSCC) differing strongly in epidermal growth factor receptor (EGFR) expression. The radionuclide (90)Y was coupled by the chelator trans-cyclohexyl-diethylene-triamine-pentaacetic acid (CHX-A″-DTPA)/linker construct to the EGFR-directed antibody cetuximab to yield (90)Y-Y-CHX-A″-DTPA-cetuximab with a specific activity of approximately 1.2 GBq/mg. EGFR expression was determined by immunofluorescence and Western blotting, cetuximab binding by fluorescence-activated cell sorter analysis, the number of DSBs by immunofluorescence staining γH2AX/53BP1-positive repair foci, and cell survival by colony formation.For the 9 HNSCC cell lines, cetuximab binding correlated with the amount of EGFR present in the cell membrane (r(2) = 0.967, P less than 0.001). When cells were exposed to (90)Y-Y-CHX-A″-DTPA-cetuximab, the number of induced DSBs increased linearly with time (r(2) = 0.968, P = 0.016). This number was found to correlate with the amount of membranous EGFR (r(2) = 0.877, P = 0.006). Most DSBs were repaired during incubation at 37°C, but the small number of remaining DSBs still correlated with the amount of membranous EGFR (24 h: r(2) = 0.977, P less than 0.001; 48 h: r(2) = 0.947, P less than 0.001). Exposure to (90)Y-Y-CHX-A″-DTPA-cetuximab also resulted in efficient cell killing, whereby the extent of cell killing correlated strongly with the respective number of remaining DSBs (r(2) = 0.989, P less than 0.001) and with the amount of membranous EGFR (r(2) = 0.967, P less than 0.001). No cell killing was observed for UTSCC15 cells with low EGFR expression, in contrast to the strong reduction of 86% measured for UTSCC14 cells showing a strong overexpression of EGFR.(90)Y-Y-CHX-A″-DTPA-cetuximab affected cell survival through the induction of DSBs. This treatment was especially efficient for HNSCC cells strongly overexpressing EGFR, whereas no effect was seen for cells with low levels of EGFR expression. Therefore, EGFR-directed radioimmunotherapy using (90)Y-Y-CHX-A″-DTPA-cetuximab appears to be a powerful tool that can be used to inactivate tumors with strong EGFR overexpression, which are often characterized by a pronounced radioresistance.
    Tipo de documento:
    Referencia
    Referencia del producto:
    05-636
    Nombre del producto:
    Anti-phospho-Histone H2A.X (Ser139) Antibody, clone JBW301

  • Two cell circuits of oriented adult hippocampal neurons on self-assembled monolayers for use in the study of neuronal communication in a defined system. 23611164

    In this study, we demonstrate the directed formation of small circuits of electrically active, synaptically connected neurons derived from the hippocampus of adult rats through the use of engineered chemically modified culture surfaces that orient the polarity of the neuronal processes. Although synaptogenesis, synaptic communication, synaptic plasticity, and brain disease pathophysiology can be studied using brain slice or dissociated embryonic neuronal culture systems, the complex elements found in neuronal synapses makes specific studies difficult in these random cultures. The study of synaptic transmission in mature adult neurons and factors affecting synaptic transmission are generally studied in organotypic cultures, in brain slices, or in vivo. However, engineered neuronal networks would allow these studies to be performed instead on simple functional neuronal circuits derived from adult brain tissue. Photolithographic patterned self-assembled monolayers (SAMs) were used to create the two-cell "bidirectional polarity" circuit patterns. This pattern consisted of a cell permissive SAM, N-1[3-(trimethoxysilyl)propyl] diethylenetriamine (DETA), and was composed of two 25 μm somal adhesion sites connected with 5 μm lines acting as surface cues for guided axonal and dendritic regeneration. Surrounding the DETA pattern was a background of a non-cell-permissive poly(ethylene glycol) (PEG) SAM. Adult hippocampal neurons were first cultured on coverslips coated with DETA monolayers and were later passaged onto the PEG-DETA bidirectional polarity patterns in serum-free medium. These neurons followed surface cues, attaching and regenerating only along the DETA substrate to form small engineered neuronal circuits. These circuits were stable for more than 21 days in vitro (DIV), during which synaptic connectivity was evaluated using basic electrophysiological methods.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • Nitric oxide repression of Nanog promotes mouse embryonic stem cell differentiation. 20075941

    Exposure of mouse embryonic stem (mES) cells to high concentrations of chemical nitric oxide (NO) donors promotes differentiation, but the mechanisms involved in this process at the gene expression level are poorly defined. In this study we report that culture of mES cells in the presence of 0.25-1.0 mM diethylenetriamine nitric oxide adduct (DETA-NO) leads to downregulation of Nanog and Oct4, the two master genes involved in the control of the pluripotent state. This action of NO was also apparent in the human ES cell line, HS 181. The suppressive action of NO on Nanog gene depends on the activation of p53 repressor protein by covalent modifications, such as pSer15, pSer315, pSer392 and acetyl Lys 379. NO-induced repression of Nanog is also associated with binding of trimethylated histone H3 and pSer315 p53 to its promoter region. In addition, exposure to 0.5 mM DETA-NO induces early differentiation events of cells with acquisition of epithelial morphology and expression of markers of definitive endoderm, such as FoxA2, Gata4, Hfn1-beta and Sox 17. This phenotype was increased when cells were treated with valproic acid (VPA) for 10 days.
    Tipo de documento:
    Referencia
    Referencia del producto:
    09-038

  • Embryonic motoneuron-skeletal muscle co-culture in a defined system. 17383103

    This paper describes a significant biotechnological advancement by creating a minimalist serum-free defined system to co-culture rat mammalian nerve and muscle cells in order to form functional neuromuscular junctions. To date, all the known in vitro nerve and muscle co-culture models use serum containing media; and while functional neuromuscular junctions (NMJ) are described, they failed to detail or quantify the minimum factors needed to recreate the NMJ in vitro. In this work, we demonstrate the development of a defined motoneuron and muscle co-culture system resulting in the formation of NMJs including: 1) a new culture technique, 2) a novel serum-free medium formulation and 3) a synthetic self-assembled monolayer (SAM) substrate N-1 [3-(trimethoxysilyl) propyl] diethylenetriamine (DETA). We characterized the culture by morphology, immunocytochemistry, electrophysiology and videography. This model system provides a better understanding of the minimal growth factor and substrate interactions necessary for NMJ formation and provides a basic system that can be utilized for nerve-muscle tissue engineering, regenerative medicine and development of limb prosthetics.
    Tipo de documento:
    Referencia
    Referencia del producto:
    CBL271
    Nombre del producto:
    Anti-Fibroblasts Antibody, clone TE-7

  • Rat Cortical Oligodendrocyte-Embryonic Motoneuron Co-Culture: An In Vitro Axon-Oligodendrocyte Interaction Model. 23493660

    Mechanisms that control the differentiation and function of oligodendrocytes in the central nervous system are complex and involve multiple inputs from the surrounding environment, including localized concentrations of growth factors and the extracellular matrix. Dissection and analysis of these inputs are key to understanding the pathology of central nervous system demyelinating diseases such as multiple sclerosis, where the differentiation of myelinating oligodendrocytes from their precursors underlies the remission phase of the disease. In vitro co-culture models provide a mechanism for the study of factors that regulate differentiation of oligodendrocyte precursors but have been difficult to develop due to the complex nature of central nervous system myelination. This study describes development of an in vitro model that merges a defined medium with a chemically modified substrate to study aspects of myelination in the central nervous system. We demonstrate that oligodendrocyte precursors co-cultured with rat embryonic motoneurons on non-biological substrate (diethylenetriamine trimethoxy-silylpropyldiethylenetriamine), can be induced to differentiate into mature oligodendrocytes that express myelin basic protein, using a serum-free medium. This defined and reproducible model of in vitro myelination could be a valuable tool for the development of treatments for demyelinating diseases such as multiple sclerosis.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • Sensitive detection of DNA modifications induced by cisplatin and carboplatin in vitro and in vivo using a monoclonal antibody. 1703029

    An assay that is based upon a monoclonal antibody (ICR4) is described that enables the quantitation of cisplatin-induced adducts on DNA down to 3 nmol Pt/g DNA (i.e., 1 Pt adduct/10(6) bases), the level necessary to produce toxic effects in cells in vitro and in vivo, using just a few micrograms of DNA. Detection is possible below this level (although probably not necessary for in vivo studies) but the cross-reactivity of unmodified DNA sequences complicates absolute quantitation of adducts. Therefore, it will be possible to investigate the distribution of clinically useful platinum drugs in patients undergoing chemotherapy. Rats of strain F344 appeared to be the best, among several tested, for the production of antibodies to modified DNA, and they were used for the production of hybridomas. Fifteen hybridomas which secreted antibodies that bound to DNA that was highly modified with cisplatin but not to normal DNA were obtained. One (ICR4) was chosen for further characterization because of its relatively strong binding to DNA modified to a moderate level with cisplatin. The characterization included the development of a sensitive competitive enzyme-linked immunoabsorbent assay and the use of DNA that had been reacted with cisplatin both in vitro and in vivo. The levels of platination of both types of DNA samples were determined by atomic absorbance spectroscopy. For DNA that had been exposed to cisplatin in vitro, 50% inhibition of antibody binding was caused by about 15 fmol of total DNA-bound Pt/assay well. At moderate levels of platination, heating of the DNA solution at 100 degrees C for 5 min increased its immunoreactivity such that 50% inhibition was caused by 2.5 fmol Pt adducts/well. Pt adducts on DNA extracted from cells that had been treated with cisplatin were less immunoreactive than DNA treated with cisplatin in vitro, but after heating the immunoreactivity increased such that 50% inhibition in the assay was caused by 2 fmol Pt adduct/well. This sensitivity was invariant over a wide range of levels of platinum adduct frequency. DNA adducts formed by the second generation anticancer drug carboplatin were recognized similarly to the adducts formed by cisplatin, but those formed by the clinically inactive trans-diamminedichloroplatinum(II) or chloro(diethylenetriamine)-platinum(II)-chloride were not significantly immunoreactive. Control DNA cross-reacted in the competitive assay but the immunoreactivity per mol base was 10(7) times lower than the immunoreactivity of cisplatin adducts.
    Tipo de documento:
    Referencia
    Referencia del producto:
    ABE416