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  • Mechanical injury to neuronal/glial cultures in microplates: role of NMDA receptors and pH in secondary neuronal cell death. 9545088

    In vitro models of traumatic injury are useful adjuncts to animal models for studying mechanisms of post-traumatic cell death. Here we describe a new in vitro model in which reproducible levels of injury are delivered by a punch device that produces 28 parallel cuts in individual wells of 96-well microplates. Cell loss is measured by LDH assay or quantitative fluorometric assay for ethidium homodimer staining. Glial cultures show cell death restricted to the initial injury site, whereas neuronal/glial cultures demonstrate substantial spread of cell loss over time. We used this model to examine the role of pH and NMDA receptors in delayed post-traumatic injury. NMDA receptor blockade by dizocilpine (MK-801) or treatment with antisense oligodeoxynucleotides directed against NMDAR1 was neuroprotective. Decreased cell death was observed under acidic conditions whereas increased extracellular pH was associated with increased, MK-801 sensitive cell loss. Advantages of our model include: reproducible trauma induction; rapid measurements of cell injury; and use of 96-well microplates which reduce time and cost. This model appears to be well-suited for the study of selected mechanisms of post-traumatic neuronal injury as well as for screening potential neuroprotective agents.
    Document Type:
    Reference
    Product Catalog Number:
    MAB328
    Product Catalog Name:
    Anti-Oligodendrocytes Antibody, clone CE-1

  • Small-molecule inhibitors of the protein methyltransferase SET7/9 identified in a high-throughput screen. 22772057

    Aberrant expression of chromatin-modifying enzymes (CMEs) is associated with a range of human diseases, including cancer. CMEs are now an important target area in drug discovery. Although the role that histone and protein (lysine) methyltransferases (PMTs) play in the regulation of transcription and cell growth is increasingly recognized, few small-molecule inhibitors of this class of enzyme have been reported. Here we describe an assay suitable for primary compound screening for the identification of PMT inhibitors. The assay followed the methylation of histones in the presence of the PMT SET7/9 and the radioactive cofactor S-adenosyl-methionine using scintillating microplates (FlashPlate) and was used to screen approximately 65 000 compounds (% coefficient of variation = 10%; Z' = 0.6). The hits identified from a library of more than 63 000 diverse small molecules included a series of rhodanine compounds with micromolar activity. A screen of the National Cancer Institute Diversity Set (2000 compounds) identified an orsein derivative that inhibited SET7/9 (~20 µM) and showed modest growth inhibition associated with the expected cellular phenotype of reduced histone methylation in a human tumor cell line. The assay represents a useful tool for the identification of inhibitors of PMT activity.
    Document Type:
    Reference
    Product Catalog Number:
    06-599
    Product Catalog Name:
    Anti-acetyl-Histone H3 Antibody

  • A high-content assay to identify small-molecule modulators of a cancer stem cell population in luminal breast cancer. 22751729

    Breast cancers expressing hormone receptors for estrogen (ER) and progesterone (PR) represent ~70% of all cases and are treated with both ER-targeted and chemotherapies, with near 40% becoming resistant. We have previously described that in some ER(+) tumors, the resistant cells express cytokeratin 5 (CK5), a putative marker of breast stem and progenitor cells. CK5(+) cells have lost expression of ER and PR, express the tumor-initiating cell surface marker CD44, and are relatively quiescent. In addition, progestins, which increase breast cancer incidence, expand the CK5(+) subpopulation in ER(+)PR(+) breast cancer cell lines. We have developed models to induce and quantitate CK5(+)ER(-)PR(-) cells, using CK5 promoter-driven luciferase (Fluc) or green fluorescent protein (GFP) reporters stably transduced into T47D breast cancer cells (CK5Pro-GFP or CK5Pro-Luc). We validated the CK5Pro-GFP-T47D model for high-content screening in 96-well microplates and performed a pilot screen using a focused library of 280 compounds from the National Institutes of Health clinical collection. Four hits were obtained that significantly abrogated the progestin-induced CK5(+) cell population, three of which were members of the retinoid family. Hence, this approach will be useful in discovering small molecules that could potentially be developed as combination therapies, preventing the acquisition of a drug-resistant subpopulation.
    Document Type:
    Reference
    Product Catalog Number:
    MAB3580
    Product Catalog Name:
    Anti-Green Fluorescent Protein Antibody

  • Microplate-based platform for combined chromatin and DNA methylation immunoprecipitation assays. 22098709

    The processes that compose expression of a given gene are far more complex than previously thought presenting unprecedented conceptual and mechanistic challenges that require development of new tools. Chromatin structure, which is regulated by DNA methylation and histone modification, is at the center of gene regulation. Immunoprecipitations of chromatin (ChIP) and methylated DNA (MeDIP) represent a major achievement in this area that allow researchers to probe chromatin modifications as well as specific protein-DNA interactions in vivo and to estimate the density of proteins at specific sites genome-wide. Although a critical component of chromatin structure, DNA methylation has often been studied independently of other chromatin events and transcription.To allow simultaneous measurements of DNA methylation with other genomic processes, we developed and validated a simple and easy-to-use high throughput microplate-based platform for analysis of DNA methylation. Compared to the traditional beads-based MeDIP the microplate MeDIP was more sensitive and had lower non-specific binding. We integrated the MeDIP method with a microplate ChIP assay which allows measurements of both DNA methylation and histone marks at the same time, Matrix ChIP-MeDIP platform. We illustrated several applications of this platform to relate DNA methylation, with chromatin and transcription events at selected genes in cultured cells, human cancer and in a model of diabetic kidney disease.The high throughput capacity of Matrix ChIP-MeDIP to profile tens and potentially hundreds of different genomic events at the same time as DNA methylation represents a powerful platform to explore complex genomic mechanism at selected genes in cultured cells and in whole tissues. In this regard, Matrix ChIP-MeDIP should be useful to complement genome-wide studies where the rich chromatin and transcription database resources provide fruitful foundation to pursue mechanistic, functional and diagnostic information at genes of interest in health and disease.
    Document Type:
    Reference
    Product Catalog Number:
    06-599
    Product Catalog Name:
    Anti-acetyl-Histone H3 Antibody

  • Detection of influenza A and B neutralizing antibodies in vaccinated ferrets and macaques using specific biotin-streptavidin conjugated antibodies. 19913054

    Several critical factors of an influenza microneutralization assay, utilizing a rapid biotin-streptavidin conjugated system for detecting influenza virus subtypes A and B, are addressed within this manuscript. Factors such as incubation times, amount of virus, cell seeding, sonication, and TPCK trypsin were evaluated for their ability to affect influenza virus neutralization in a microplate-based neutralization assay using Madin-Darby canine kidney (MDCK) cells. It is apparent that the amount of virus used in the assay is the most critical factor to be optimized in an influenza microneutralization assay. Results indicate that 100xTCID(50) of influenza A/Solomon Islands/03/2006 (H1N1) virus overloads the assay and results in no, to low, neutralization, in both ferret and macaque sera, respectively, whereas using 6xTCID(50) resulted in significantly improved neutralization. Conversely, strong neutralization was observed against 100xTCID(50) of B/Malaysia/2506/04 virus. In this manuscript the critical factors described above were optimized and the results indicate that the described biotin-streptavidin conjugated influenza microneutralization assay is a rapid and robust method for detecting the presence of functional, influenza virus-neutralizing antibodies.
    Document Type:
    Reference
    Product Catalog Number:
    MAB8258B
    Product Catalog Name:
    Anti-Influenza A Antibody, nucleoprotein, clone A3, biotin-conjugated

  • Methods for Evaluating Cell-Specific, Cell-Internalizing RNA Aptamers. 23894227

    Recent clinical trials of small interfering RNAs (siRNAs) highlight the need for robust delivery technologies that will facilitate the successful application of these therapeutics to humans. Arguably, cell targeting by conjugation to cell-specific ligands provides a viable solution to this problem. Synthetic RNA ligands (aptamers) represent an emerging class of pharmaceuticals with great potential for targeted therapeutic applications. For targeted delivery of siRNAs with aptamers, the aptamer-siRNA conjugate must be taken up by cells and reach the cytoplasm. To this end, we have developed cell-based selection approaches to isolate aptamers that internalize upon binding to their cognate receptor on the cell surface. Here we describe methods to monitor for cellular uptake of aptamers. These include: (1) antibody amplification microscopy, (2) microplate-based fluorescence assay, (3) a quantitative and ultrasensitive internalization method ("QUSIM") and (4) a way to monitor for cytoplasmic delivery using the ribosome inactivating protein-based (RNA-RIP) assay. Collectively, these methods provide a toolset that can expedite the development of aptamer ligands to target and deliver therapeutic siRNAs in vivo.
    Document Type:
    Reference
    Product Catalog Number:
    AB9872
    Product Catalog Name:
    Anti-TrkB Antibody

  • Rapid colorimetric assay for cell viability: application to the quantitation of cytotoxic and growth inhibitory lymphokines. 6609997

    A rapid colorimetric microtiter assay has been developed to detect cytotoxic lymphokines produced by human lymphocytes activated with lectins or tumor cells. The viability of lymphotoxin-treated target cells was detected using a tetrazolium dye that is reduced to a blue formazan by living but not dead cells. The amount of dye formed was quantitated using a microplate spectrophotometer (ELISA plate reader) and visual observations confirmed the amount of formazan dye produced was directly proportional to the number of viable target cells. The advantages of using this colorimetric method are that it requires no washing steps or radioisotopes and its precision and rapidity. Optimal conditions were established using the murine L929 and human ESH -5L cell lines as target cells for detecting lymphotoxins produced by human lymphocytes. The data indicate that the L929 cell line was 10-50-fold more sensitive than the ESH -5L line to the lytic activity of cytotoxins produced by human phytohemagglutinin-P-activated T lymphocytes, or the cytotoxins produced by peripheral blood lymphocytes stimulated with various tumor cell lines. This assay system was also useful in detecting antibodies capable of neutralizing lymphotoxin activity and thus should be a suitable method to aid in the molecular characterization of these lymphokines.
    Document Type:
    Reference
    Product Catalog Number:
    Multiple
    Product Catalog Name:
    Multiple