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2,088 result(s) for "Chang, David D."
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Inhibition of Stat1-Mediated Gene Activation by PIAS1
STAT (signal transducer and activator of transcription) proteins are latent cytoplasmic transcription factors that become activated by tyrosine phosphorylation in response to cytokine stimulation. Tyrosine phosphorylated STATs dimerize and translocate into the nucleus to activate specific genes. Different members of the STAT protein family have distinct functions in cytokine signaling. Biochemical and genetic analysis has demonstrated that Stat1 is essential for gene activation in response to interferon stimulation. Although progress has been made toward understanding STAT activation, little is known about how STAT signals are down-regulated. We report here the isolation of a family of PIAS (protein inhibitor of activated STAT) proteins. PIAS1, but not other PIAS proteins, blocked the DNA binding activity of Stat1 and inhibited Stat1-mediated gene activation in response to interferon. Coimmunoprecipitation analysis showed that PIAS1 was associated with Stat1 but not Stat2 or Stat3 after ligand stimulation. The in vivo PIAS1-Stat1 interaction requires phosphorylation of Stat1 on Tyr-701. These results identify PIAS1 as a specific inhibitor of Stat1-mediated gene activation and suggest that there may exist a specific PIAS inhibitor in every STAT signaling pathway.
Opportunities and Challenges in Implementation of Multiparameter Single Cell Analysis Platforms for Clinical Translation
The high‐content interrogation of single cells with platforms optimized for the multiparameter characterization of cells in liquid and solid biopsy samples can enable characterization of heterogeneous populations of cells ex vivo. Doing so will advance the diagnosis, prognosis, and treatment of cancer and other diseases. However, it is important to understand the unique issues in resolving heterogeneity and variability at the single cell level before navigating the validation and regulatory requirements in order for these technologies to impact patient care. Since 2013, leading experts representing industry, academia, and government have been brought together as part of the Foundation for the National Institutes of Health (FNIH) Biomarkers Consortium to foster the potential of high‐content data integration for clinical translation.
Characterization of transformation related genes in oral cancer cells
A cDNA representational difference analysis (cDNA-RDA) and an arrayed filter technique were used to characterize transformation-related genes in oral cancer. From an initial comparison of normal oral epithelial cells and a human papilloma virus (HPV)-immortalized oral epithelial cell line, we obtained 384 differentially expressed gene fragments and arrayed them on a filter. Two hundred and twelve redundant clones were identified by three rounds of back hybridization. Sequence analysis of the remaining clones revealed 99 unique clones corresponding to 69 genes. The expression of these transformation related gene fragments in three nontumorigenic HPV-immortalized oral epithelial cell lines and three oral cancer cell lines were simultaneously monitored using a cDNA array hybridization. Although there was a considerable cell line-to-cell line variability in the expression of these clones, a reliable prediction of their expression could be made from the cDNA array hybridization. Our study demonstrates the utility of combining cDNA-RDA and arrayed filters in high-throughput gene expression difference analysis. The differentially expressed genes identified in this study should be informative in studying oral epithelial cell carcinogenesis.
Gene expression in epithelial ovarian carcinoma
We analysed the mRNA levels corresponding to 12,600 transcripts in primary cultures of ovarian epithelial cells derived from nine normal ovaries and 21 epithelial ovarian carcinoma. The class distinction and hierarchical clustering of expression data revealed a clear distinction in gene expression between normal and carcinoma-derived ovarian epithelial cells. Comparison of expression levels revealed 111 genes with mean expression values of >2.5-fold higher in carcinoma cells. Similarly, 62 genes were expressed at >2.5-fold higher levels in normal ovarian epithelial cells. For a few selected genes, we demonstrate that the pattern of differential expression observed in cultured epithelial cells is present in the normal ovaries and epithelial ovarian carcinoma. Use of cultured epithelial cells represents a novel strategy to study gene expression in a cell-type specific manner.
EPLIN, Epithelial protein lost in neoplasm
We have identified a novel cytoskeletal protein, EPLIN (Epithelial Protein Lost In Neoplasm), that is preferentially expressed in human epithelial cells. Two EPLIN isoforms, a 600 amino acid EPLIN-alpha and a 759 amino acid EPLIN-beta, are detected in primary epithelial cells of oral mucosa, prostate and mammary glands. The expression of EPLIN-alpha is either down-regulated or lost in the majority of oral cancer cell lines (8/8), prostate cancer cell lines (4/4) and xenograft tumors (3/3), and breast cancer cell lines (5/6). The amino acid sequence of EPLIN is characterized by the presence of a single centrally located LIM domain. Both EPLIN isoforms localize to filamentous actin and suppress cell proliferation when overexpressed. These findings indicate that the loss of EPLIN seen in cancer cells may play a role in cancer progression.
Exon Amplification: A Strategy to Isolate Mammalian Genes Based on RNA Splicing
We have developed a method, exon amplification, for fast and efficient isolation of coding sequences from complex mammalian genomic DNA. This method is based on the selection of RNA sequences, exons, which are flanked by functional 5' and 3' splice sites. Fragments of cloned genomic DNA are inserted into an intron, which is flanked by 5' and 3' splice sites of the human immunodeficiency virus 1 tat gene contained within the plasmid pSPL1. COS-7 cells are transfected with these constructs, and the resulting RNA transcripts are processed in vivo. Splice sites of exons contained within the inserted genomic fragment are paired with splice sites of the flanking tat intron. The resulting mature RNA contains the previously unidentified exons, which can then be amplified via RNA-based PCR and cloned. Using this method, we have isolated exon sequences from cloned genomic fragments of the murine Na,K-ATPase α1-subunit gene. We have also screened randomly selected genomic clones known to be derived from a segment of human chromosome 19 and have isolated exon sequences of the DNA repair gene ERCC1. The sensitivity and ease of the exon amplification method permit screening of 20-40 kilobase pairs of genomic DNA in a single transfection. This approach will be extremely useful for rapid identification of mammalian exons and the genes from which they are derived as well as for the generation of chromosomal transcription maps.
A Mammalian Mitochondrial RNA Processing Activity Contains Nucleus-Encoded RNA
Ribonuclease mitochondrial RNA processing, a site-specific endoribonuclease involved in primer RNA metabolism in mammalian mitochondria, requires an RNA component for its activity. On the basis of copurification and selective inactivation with complementary oligonucleotides, a 135-nucleotide RNA species, not encoded in the mitochondrial genome, is identified as the RNA moiety of the endoribonuclease. This finding implies transport of a nucleus-encoded RNA, essential for organelle DNA replication, to the mitochondrial matrix.
Comparison of methotrexate monotherapy with a combination of methotrexate and etanercept in active, early, moderate to severe rheumatoid arthritis (COMET): a randomised, double-blind, parallel treatment trial
Remission and radiographic non-progression are goals in the treatment of early rheumatoid arthritis. The aim of the combination of methotrexate and etanercept in active early rheumatoid arthritis (COMET) trial is to compare remission and radiographic non-progression in patients treated with methotrexate monotherapy or with methotrexate plus etanercept. 542 outpatients who were methotrexate-naive and had had early moderate-to-severe rheumatoid arthritis for 3–24 months were randomly assigned to receive either methotrexate alone titrated up from 7·5 mg a week to a maximum of 20 mg a week by week 8 or methotrexate (same titration) plus etanercept 50 mg a week. Coprimary endpoints at 52 weeks were remission measured with the disease activity score in 28 joints (DAS28) and radiographic non-progression measured with modified total Sharp score. Treatment was allocated with a computerised randomisation and enrolment system, which masked both participants and carers. Analysis was done by modified intention to treat with last observation carried forward for missing data. This study is registered with ClinicalTrials.gov, number NCT00195494). 274 participants were randomly assigned to receive combined treatment and 268 methotrexate alone. 132 of 265 (50%, 95% CI 44–56%) patients who took combined treatment and were available for assessment achieved clinical remission compared with 73 of 263 (28%, 23–33%) taking methotrexate alone (effect difference 22·05%, 95%CI 13·96–30·15%, p<0·0001). 487 evaluable patients had severe disease (DAS28>5·1). 196 of 246 (80%, 75–85%) and 135 of 230 (59%, 53–65%), respectively, achieved radiographic non-progression (20·98%, 12·97–29·09%, p<0·0001). Serious adverse events were similar between groups. Both clinical remission and radiographic non-progression are achievable goals in patients with early severe rheumatoid arthritis within 1 year of combined treatment with etanercept plus methotrexate. Wyeth Research.
Messenger RNA Transport and HIV rev Regulation
The mechanism of transport of messenger ribose nucleic acid (mRNA) molecules from the nucleus of the cell where they are synthesized from genes, to the cytoplasm of the cell, where proteins are synthesized from them, is not understood. RNA is modified in many different ways before it is transported. The processing that occurs is unique to mRNA, and appears to involve the regulation of the transport of molecules. RNA combines with proteins to form nuclear ribonucleoprotein complexes, and known complexes have been found in certain regions of the cell. An example of a modification that occurs to the mRNA is splicing, where regions of RNA that do not code for proteins are removed from the genetic information. Splicing involves the formation of a complex, known as the spliceosome. The spliceosome appears to associate with the nuclear matrix and the mRNA is thought to be transported through some type of matrix channels. Thus, RNA splicing and RNA transport appear to be connected. Studies with the human immunodeficiency virus type-1 (HIV-1), a type of retrovirus, or RNA virus, give further evidence for the connection between modification and transport. Production of different mRNA from the HIV-1 genome occurs at different times during viral infection. At first, mRNA that codes for molecules involved in the regulation of other processes is transported from the nucleus. The peptide rev binds to a particular RNA sequence, causing the inhibition of splicing. For viral replication to occur, it is necessary that molecules of RNA that are not spliced are transported to the cytoplasm of the cell, because new viruses are made from the unspliced RNA. Thus, the binding of the rev protein on RNA allows unmodified RNA to be transported to the cytoplasm of the cell. This example shows the complexity of RNA modification and transport. It also offers a possible approach to stop viral replication, and thus infection, by inhibiting the rev peptide. (Consumer Summary produced by Reliance Medical Information, Inc.)
Intraoperative Sentinel Events in the Era of Surgical Safety Checklists: Results of a National Survey
Objective Despite the implementation of advanced health care safety systems including checklists, preventable perioperative sentinel events continue to occur and cause patient harm, disability, and death. We report on findings relating to otolaryngology practices with surgical safety checklists, the scope of intraoperative sentinel events, and institutional and personal response to these events. Study Design Survey study. Setting Anonymous online survey of otolaryngologists. Methods Members of the American Academy of Otolaryngology–Head and Neck Surgery were asked about intraoperative sentinel events, surgical safety checklist practices, fire safety, and the response to patient safety events. Results In total, 543 otolaryngologists responded to the survey (response rate 4.9% = 543/11,188). The use of surgical safety checklists was reported by 511 (98.6%) respondents. At least 1 patient safety event in the past 10 years was reported by 131 (25.2%) respondents; medication errors were the most commonly reported (66 [12.7%] respondents). Wrong site/patient/procedure events were reported by 38 (7.3%) respondents, retained surgical items by 33 (6.4%), and operating room fire by 18 (3.5%). Although 414 (79.9%) respondents felt that time-outs before the case have been the single most impactful checklist component to prevent serious patient safety events, several respondents also voiced frustrations with the administrative burden. Conclusion Surgical safety checklists are widely used in otolaryngology and are generally acknowledged as the most effective intervention to reduce patient safety events; nonetheless, intraoperative sentinel events do continue to occur. Understanding the scope, causes, and response to these events may help to prioritize resources to guide quality improvement initiatives in surgical safety practices.