Prevention of coronary restenosis by stenting

Balloon angioplasty fails to provide acceptable long-term results for a significant proportion of patients. An intravascular mechanical support, developed with the aim of preventing restenosis and acute closure of diseased arteries after transluminal angioplasty, was implanted in 44 patients (39 male and five female), aged from 35 to 70 years (mean 56 years) with documented restenosis of native coronary artery (41 stents) and bypass grafts (12 stents). In the group of bypass graft patients there was no local restenosis and no major complication. In patients in whom stents were placed in native coronary arteries, the complication rate was higher (two patients died after coronary bypass surgery). One patient died suddenly at home. Except for one patient, in whom a new lesion developed proximally with extension into the stent, no case of restenosis could be observed. Despite the still relatively high complication rate, we feel that stenting may present a rational approach to the unresolved problem of restenosis after coronary angioplast

Prevention of coronary restenosis by stenting

Balloon angioplasty fails to provide acceptable long-term results for a significant proportion of patients. An intravascular mechanical support, developed with the aim of preventing restenosis and acute closure of diseased arteries after transluminal angioplasty, was implanted in 44 patients (39 male and five female), aged from 35 to 70 years (mean 56 years) with documented restenosis of native coronary artery (41 stents) and bypass grafts (12 stents). In the group of bypass graft patients there was no local restenosis and no major complication. In patients in whom stents were placed in native coronary arteries, the complication rate was higher (two patients died after coronary bypass surgery). One patient died suddenly at home. Except for one patient, in whom a new lesion developed proximally with extension into the stent, no case of restenosis could be observed. Despite the still relatively high complication rate, we feel that stenting may present a rational approach to the unresolved problem of restenosis after coronary angioplasty

Novel Functional MAR Elements of Double Minute Chromosomes in Human Ovarian Cells Capable of Enhancing Gene Expression

Double minute chromosomes or double minutes (DMs) are cytogenetic hallmarks of extrachromosomal genomic amplification and play a critical role in tumorigenesis. Amplified copies of oncogenes in DMs have been associated with increased growth and survival of cancer cells but DNA sequences in DMs which are mostly non-coding remain to be characterized. Following sequencing and bioinformatics analyses, we have found 5 novel matrix attachment regions (MARs) in a 682 kb DM in the human ovarian cancer cell line, UACC-1598. By electrophoretic mobility shift assay (EMSA), we determined that all 5 MARs interact with the nuclear matrix in vitro. Furthermore, qPCR analysis revealed that these MARs associate with the nuclear matrix in vivo, indicating that they are functional. Transfection of MARs constructs into human embryonic kidney 293T cells showed significant enhancement of gene expression as measured by luciferase assay, suggesting that the identified MARS, particularly MARs 1 to 4, regulate their target genes in vivo and are potentially involved in DM-mediated oncogene activation

Nuclear Scaffold Attachment Sites within ENCODE Regions Associate with Actively Transcribed Genes

The human genome must be packaged and organized in a functional manner for the regulation of DNA replication and transcription. The nuclear scaffold/matrix, consisting of structural and functional nuclear proteins, remains after extraction of nuclei and anchors loops of DNA. In the search for cis-elements functioning as chromatin domain boundaries, we identified 453 nuclear scaffold attachment sites purified by lithium-3,5-iodosalicylate extraction of HeLa nuclei across 30 Mb of the human genome studied by the ENCODE pilot project. The scaffold attachment sites mapped predominately near expressed genes and localized near transcription start sites and the ends of genes but not to boundary elements. In addition, these regions were enriched for RNA polymerase II and transcription factor binding sites and were located in early replicating regions of the genome. We believe these sites correspond to genome-interactions mediated by transcription factors and transcriptional machinery immobilized on a nuclear substructure

Inhibitor of caspase-activated DNase expression enhances caspase-activated DNase expression and inhibits oxidative stress-induced chromosome breaks at the mixed lineage leukaemia gene in nasopharyngeal carcinoma cells

BACKGROUND: Nasopharyngeal carcinoma (NPC) is commonly found in Asia, especially among the Chinese ethnic group. Chromosome rearrangements are common among NPC patients. Although the mechanism underlying the chromosome rearrangements in NPC is unclear, various mechanisms including activation of caspase-activated DNase (CAD) were proposed to contribute to chromosome rearrangements in leukaemia. Activation of CAD can be initiated by multiple agents, including oxidative stress, which is well implicated in carcinogenesis. CAD is the main enzyme that causes DNA fragmentation during apoptosis, and CAD is also implicated in promoting cell differentiation. In view of the role of oxidative stress in carcinogenesis and CAD activation, and since CAD was suggested to contribute to chromosome rearrangement in leukaemia, we hypothesise that oxidative stress-induced CAD activation could be one of the mechanisms that leads to chromosome rearrangements in NPC. METHODS: SUNEI cells were treated with various concentrations of H(2)O(2) for different period of time to ensure that cells undergo H(2)O(2)-induced MLL gene cleavage. Transfections with hCAD, mCAD, mutant hCAD, or cotransfection with hCAD and mICAD, and cotransfection with mutant hCAD and mICAD were performed. Gene expression was confirmed by Western blotting and MLL gene cleavage was assessed by inverse polymerase chain reaction (IPCR). RESULTS: Treatment with H(2)O(2) clearly induces cleavages within the MLL gene which locates at 11q23, a common deletion site in NPC. In order to investigate the role of CAD, CAD was overexpressed in SUNE1 cells, but that did not result in significant changes in H(2)O(2)-induced MLL gene cleavage. This could be because CAD requires ICAD for proper folding. Indeed, by overexpressing ICAD alone or co-expressing ICAD with CAD, Western blotting showed that CAD was expressed. In addition, ICAD overexpression also suppressed H(2)O(2)-induced MLL gene cleavage, suggesting a possible role of CAD in initiating chromosome cleavage during oxidative stress. CONCLUSIONS: Oxidative stress mediated by H(2)O(2) induces cleavage of the MLL gene, most likely via the caspase-activated DNase, CAD, and CAD expression requires ICAD. Since the MLL gene is located at 11q23, a common deletion site in NPC, thus stress-induced CAD activation may represent one of the mechanisms leading to chromosome rearrangement in NPC

Regulation of c-fos expression by RNA polymerase elongation competence.

The molecular mechanisms underlying transcription elongation and their role in gene regulation are poorly characterized in eukaryotes. A number of genes, however, have been proposed to be regulated at the level of transcription elongation, including c-myc, c-fos and c-myb. Here, we analyze the control of transcription elongation at the mouse c-fos gene at the nucleotide level in intact cells. We find that RNA polymerases are engaged in the promoter-proximal part of the gene in the absence of gene activation signals and mRNA synthesis. Importantly, we determine that the engaged RNA polymerases originate from a continuous initiation of transcription which, in the absence of gene activation signals, terminate close to the promoter. We also observe that the c-fos gene presents an active chromatin conformation, with the promoter and upstream regulatory sequences constitutively occupied by proteins, accounting for the continuous initiation of RNA polymerase complexes. We propose that activation of c-fos gene expression results primarily from the assembly of elongation-competent RNA polymerases that can transcribe the complete gene. Our results suggest that the engaged RNA polymerases found downstream of a number of other eukaryotic promoters may be associated with transcription termination of elongation-incompetent polymerases in the absence of activating signals