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Berdyyeva Tamara K - - 2005
The decrease in elasticity of epithelial tissues with ageing contributes to many human diseases. This change was previously attributed to increased crosslinking of extracellular matrix proteins. Here we show that individual human epithelial cells also become significantly more rigid during ageing in vitro. Using atomic force microscopy (AFM), we found ...
Brunori Michele - - 2005
Telomeres are nucleoprotein complexes that cap the end of eukaryotic chromosomes and are essential for their function and stability. Telomerase, a reverse transcriptase that extends the single-stranded G-rich 3' protruding ends of chromosomes, stabilizes telomere length in germ line cells and regenerative tissues as well as in tumor cells. In ...
Voß, Martin Henner
Background: Cellular senescence is a state which normal cells enter following an extensive period of proliferation or upon exposure to various kinds of stress. The senescence program involves G1 arrest accompanied by dramatic changes in cell function and morphology. The molecular mechanisms that govern these changes are at this point ...
Berman H - - 2005
Morphologically normal foci of epithelial cells exhibiting p16 inactivation have been found in several tissues and may be precursors to cancer. Our previous work demonstrates that cells lacking p16(INK4A) activity exhibit phenotypes associated with malignancy (Romanov et al. 2001). The acquisition of genomic instability occurs through the activation of telomeric ...
Davis Terence - - 2005
Studies on telomere and telomerase biology are fundamental to the understanding of human ageing, and age-related diseases such as cancer. However, human studies are hampered by the lack of fully reflective animal model systems. Here we describe basic studies of telomere length and telomerase activity in sheep tissues and cells. ...
Rossi Michael J - - 2005
OBJECTIVES: Head and neck squamous cell carcinoma (HNSCC) is notoriously resistant to chemotherapy. The sphingolipid ceramide and its analogs have been demonstrated to exert antitumor activity in many cell types; however, the effectiveness of these analogs has been limited by potency and solubility. This study focuses on the effects of ...
Zou Jian - - 2005
OBJECTIVE: To study the killing effects of oxymatrine (OM) on a human colon cancer cell line, SW1116, and evaluate its antineoplastic mechanism. METHODS: Methyl thiazolyl tetrazolium (MTT) analysis, flow cytometry, polymerase chain reaction (PCR)-enzyme linked immunosorbent assay (ELISA) and RT-PCR methods were used respectively to determine the killing effects of ...
Bates Steven E - - 2005
The progression of a normal cell to senescence in vivo and in vitro is accompanied by a reduction in the length of the telomeres, the chromosome capping segments at the end of each linkage group. However, overexpression of the reverse transcriptase subunit (HTERT) of the ribonucleoprotein telomerase restores telomere length ...
Colangelo Donato - - 2005
Telomerase is a ribonucleoprotein polymerase that maintains the length of telomeric DNA by adding hexameric units (TTAGGG) to the ends of the chromosomes. This mechanism prevents replicative senescence, thus conferring unlimited proliferative potential to cells. Telomerase reactivation has been detected in most human tumour tissue, indicating that the enzyme may ...
Stroikin Yuri - - 2005
Imperfect autophagic degradation of oxidatively damaged macromolecules and organelles (so-called biological "garbage") is considered an important contributor to ageing and consequent death of postmitotic (non-dividing) cells, such as neurons and cardiac myocytes. In contrast, proliferating cells apparently escape senescence by a continuous dilution and repair of damaged structures during division. ...
Carracedo Julia - - 2005
Hemodialysis treatment induces mononuclear cell activation particularly if cellulosic hemodialysis membrane is used. In normal cells, repeated activation induce a process of accelerate cellular senescence. The aim of the present study was to evaluate whether the mononuclear cell activation associated to hemodialysis with cellulosic membranes favors a process of accelerate ...
Park Sun Young - - 2004
We have reported that mitochondrial DNA-depleted rho(0) cells are resistant to cell death. Because aged cells have frequent mitochondrial DNA mutations, the resistance of rho(0) cells against cell death might be related to the apoptosis resistance of aged cells and frequent development of cancers in aged individuals. We studied if ...
Ramirez Ruben D - - 2004
By expressing two genes (hTERT and Cdk4), we have developed a method to reproducibly generate continuously replicating human bronchial epithelial cell (HBEC) lines that provide a novel resource to study the molecular pathogenesis of lung cancer and the differentiation of bronchial epithelial cells. Twelve human bronchial epithelial biopsy specimens obtained ...
Mason Douglas X - - 2004
Senescence irreversibly arrests the proliferation of cells that have sustained significant cellular stress. Replicative senescence, due to the shortening and dysfunction of telomeres, appears to provide a barrier to the immortalization of cells and development of cancer. In normal human fibroblasts, senescence induced by oncogenic H-ras displays a nearly identical ...
Michelle A. Wood
The mechanism of senescence, permanent G1 arrest, is gradually becoming elucidated; however, the exact function of senescence remains unclear. A marker assay detecting the acidic senescence-associated beta-galactosidase (saβgal) has been used as an indicator for cellular senescence. However, more recently, others have shown that expression of this low pH saβgal ...
Wang Xi-Shan - - 2004
AIM: To investigate the inhibitory effect of phosphorothioate anti-sense oligodeoxynucleotides (PASODN) on colorectal cancer LS-174T cells in vitro and the mechanism of inhibition of telomerase activity in these cells. METHODS: PASODN were used to infect LS-174T cells and block human telomerase RNA (hTR) through anti-sense technology. The inhibitory effect of ...
Cabuy Erik - - 2004
BACKGROUND: Telomeres are specialized nucleoprotein structures at chromosome ends that undergo dynamic changes after each cell cycle. Understanding the mechanisms of telomere dynamics is critically dependent on the ability to accurately measure telomere length in a cell population of interest. Techniques such as Southern blot, which measures average telomere length, ...
Itaya Hiroshi - - 2004
PURPOSE: To determine whether iris pigment epithelium (IPE) cells can attach to aged submacular human Bruch's membrane and to assess whether IPE cells express the integrin subunits that may be necessary to bind to the known extracellular matrix ligands present in Bruch's membrane. METHODS: IPE cells were seeded onto the ...
Lee Eunju - - 2004
Although estrogen has been considered as a sex hormone for decades, recent reports suggest that estrogen might modulate the development and physiological function of the brain. In addition, the subcellular localization of estrogen receptors (ERs) has shown their presence within both the perinuclear cytoplasm and nuclei, suggesting that these ERs ...
Jenkins M S - - 2004
Fluid shear and other mechanical forces play an important role in the normal biophysical, biochemical, and gene regulatory responses of vertebrate tissue that are reflected in the expression of normal cell differentiation, growth, and function. Despite some promising work reported on the application of the quartz crystal microbalance (QCM) to ...
Yang Seong Wook - - 2004
Telomeres are specialized nucleoprotein complexes that are essential for preserving chromosome integrity in eukaryotic cells. Several potential telomere binding proteins have recently been identified in higher plants, but nothing is known about their in vivo functions. We previously identified NgTRF1 as a double-stranded telomeric repeat binding factor in tobacco (Nicotiana ...
Satyanarayana Ande - - 2004
Cellular senescence induced by different stresses and telomere shortening appears to play an important role in the aging process. The products of the INK4a/ARF locus--p16INK4a and ARF--arrest cell proliferation at the senescence stage by exerting their effects on retinoblastoma protein- and p53-mediated responsive pathways. A study in this issue of ...
You Seungkwon - - 2004
Although primary bovine embryonic fibroblast (BEF) cells have previously been used as nucleus-donors for nuclear transfer (NT), it has now been proposed to use BEF cells to generate cloned cows that were genetically modified by transgenic or a knock-out system. A major limitation to gene targeting somatic cells, however, is ...
Sun Yubo - - 2004
To examine whether the life span of fibroblast-like synoviocytes (FLSs) can be extended and to establish FLS cell lines that preserve the characteristics of primary FLSs, we introduced human catalytic subunit of telomerase (hTERT) gene into human osteoarthritic (OA) FLSs. Two hTERT-transduced clonal cell lines were established and one line, ...
Yokoo Seiichi - - 2004
The cellular life-span of cultivated human skin epidermis keratinocytes NHEK-F was shown to be extended up to 150% of population doubling levels (PDLs) by repetitive addition with two autooxidation-resistant derivatives of ascorbic acid (Asc), Asc-2-O-phosphate (Asc2P), and Asc-2-O-alpha-glucoside (Asc2G), respectively, but to be not extended with Asc itself. In contrast, ...
Shay Jerry W - - 2005
Telomere dynamics are a critical component of both aging and cancer. Telomeres progressively shorten in almost all dividing cells and most human cells do not express or maintain sufficient telomerase activity to fully maintain telomeres. There is accumulating evidence that when only a few telomeres are short, they form end-associations, ...
Incles Christopher M - - 2004
The trisubstituted acridine derivative BRACO-19 has been designed to interact with and stabilize the quadruplex DNA structures that can be formed by folding of the single-stranded repeats at the 3' end of human telomeres. We suggest that the BRACO-19 complex inhibits the catalytic function of telomerase in human cancer cells ...
Peterson W J - - 2004
Generally, fibroblast-like cells and other types of human cells have been used to demonstrate the principles of replicative senescence in vitro and in vivo. These cells go through three stages of proliferation, including vigorous proliferation, declining proliferation and quiescence or no proliferation. Any variation of this process occurring in osteoprogenitor ...
van Doorn Wouter G - - 2004
The terms senescence and programmed cell death (PCD) have led to some confusion. Senescence as visibly observed in, for example, leaf yellowing and petal wilting, has often been taken to be synonymous with the programmed death of the constituent cells. PCD also obviously refers to cells, which show a programme ...
Xhemalce Blerta B Unité de la Dynamique du Génome, Institut Pasteur, Paris Cedex, - - 2004
Sumoylation represents a conserved mechanism of post-translational protein modification. We report that Pli1p, the unique fission yeast member of the SP-RING family, is a SUMO E3 ligase in vivo and in vitro. pli1Delta cells display no obvious mitotic growth defects, but are sensitive to the microtubule-destabilizing drug TBZ and exhibit ...
Schmid Ingrid - - 2004
Telomere sequences at the end of chromosomes control somatic cell division; therefore, telomere length in a given cell population provides information about its replication potential. This unit describes a method for flow cytometric measurement of telomere length in subpopulations using fluorescence in situ hybridization of fluorescently-labeled probes (Flow-FISH) without prior ...
Tsuji Takao - - 2004
Cellular senescence is a state of irreversible growth arrest induced either by telomere shortening (replicative senescence) or by telomere-independent signals (stress-induced senescence). The alveolar epithelium is often injured by a variety of inhaled toxins, including cigarette smoke (CS). In the present study, we investigated whether exposure to CS induces senescence ...
Leonetti Carlo - - 2004
This study had two goals: 1) to evaluate the biological effect of the novel pentacyclic acridine 3,11-difluoro-6,8,13-trimethyl-8H-quino[4,3,2-kl]acridinium methosulfate (RHPS4) on human melanoma lines possessing long telomeres, and 2) to elucidate the relationship between G-quadruplex-based telomerase inhibitor-induced cellular effects and telomere length/dysfunction. The cellular pharmacological effects of RHPS4 have been evaluated ...
Martinez Natalia - - 2004
BACKGROUND: The fusion protein RUNX1-CBFA2T1 associated with t(8;21)-positive acute myeloid leukaemia is a potent inhibitor of haematopoetic differentiation. The role of RUNX1-CBFA2T1 in leukaemic cell proliferation is less clear. We examined the consequences of siRNA-mediated RUNX1-CBFA2T1 depletion regarding proliferation and clonogenicity of t(8;21)-positive cell lines. METHODS: The t(8;21)-positive cell line ...
Mondello Chiara - - 2004
Telomeres are specialized high-order chromatin structures that cap the ends of eukaryotic chromosomes. In vertebrates, telomeric DNA is composed of repetitions of the TTAGGG hexanucleotide, is bound to a set of specific proteins, and is elongated by the reverse transcriptase enzyme telomerase. Telomerase activity is promptly detected in cells with ...
Soloff Melvyn S - - 2004
An examination of cellular processes involved in myometrial function has been greatly assisted by the use of human myometrial cells in primary culture. However, these cells can be used only for several passages before they senesce, and responses to various agents change with time in culture. The use of transformed ...
Kawado Takeshi - - 2004
Rapid senescence was induced into human lung adenocarcinoma A549 cells by transforming growth factor-beta1. Lectin blot analysis of membrane glycoprotein samples showed that the binding of Ricinus communis agglutinin-I to protein bands increased markedly while those of other lectins together with protein components did not change significantly with senescence. This ...
Rolland Morgane - - 2004
Primary goat synovial membrane (GSM) cells are widely used to study small ruminant lentiviruses (SRLV), i.e. maedi visna virus (MVV) and caprine arthritis-encephalitis virus (CAEV), but their limited life-span of 15-20 passages in vitro is problematic. Here, we report that ectopic expression of the catalytic subunit of human telomerase (hTERT) ...
Borrás Consuelo - - 2004
Changes in telomerase activity have been associated either with cancer, when activity is increased, or with cell cycle arrest when it is decreased. We report that glutathione, a physiological antioxidant present at high intracellular concentrations, regulates telomerase activity in cells in culture. Telomerase activity increases in 3T3 fibroblasts before exponential ...
Purev E - - 2004
Vitamin A is an essential nutrient important for growth, vision, embryonic development, immune response and reproduction. Various retinoids have been shown to be effective chemotherapeutic and chemopreventive agents for a number of human cancers. Telomeres are nucleoprotein structures found at the end of chromosomes. During cellular division, the telomeres in ...
Satyanarayana A - - 2004
Replicative senescence is induced by critical telomere shortening and limits the proliferation of primary cells to a finite number of divisions. To characterize the activity status of the replicative senescence program in the context of cell cycle activity, we analyzed the senescence phenotypes and signaling pathways in quiescent and growth-stimulated ...
Kassem Moustapha - - 2004
The use of human telomerase reverse transcriptase (hTERT)-immortalized cells in tissue engineering protocols is a potentially important application of telomere biology. Several human cell types have been created that overexpress the hTERT gene with enhanced telomerase activity, extended life span and maintained or even improved functional activities. Furthermore, some studies ...
Lee Kwang M - - 2004
A major obstacle to the immortalization of primary human cells and the establishment of human cell lines is telomere-controlled senescence. Telomere-controlled senescence is caused by the shortening of telomeres that occurs each time somatic human cells divide. The enzyme telomerase can prevent the erosion of telomeres and block the onset ...
Abrahám Hajnalka - - 2004
BACKGROUND: In previous studies, lower IQ scores and educational difficulties of preterm children were correlated with the reduced size of several brain areas, including the cerebellum and the hippocampus. The most plausible reason for reduction would be the reduced cell formation following premature birth. However, no data are available about ...
Reverter-Branchat Gemma - - 2004
Oxidative modifications of cellular components have been described as one of the main contributions to aged phenotype. In Saccharomyces cerevisiae, two distinct life spans can be considered, replicative and chronological. The relationship between both aging models is still not clear despite suggestions that these phenomena may be related. In this ...
Herbig Utz U Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, - - 2004
Cellular senescence can be triggered by telomere shortening as well as a variety of stresses and signaling imbalances. We used multiparameter single-cell detection methods to investigate upstream signaling pathways and ensuing cell cycle checkpoint responses in human fibroblasts. Telomeric foci containing multiple DNA damage response factors were assembled in a ...
Schaetzlein Sonja - - 2004
The enzyme telomerase is active in germ cells and early embryonic development and is crucial for the maintenance of telomere length. Whereas the different length of telomeres in germ cells and somatic cells is well documented, information on telomere length regulation during embryogenesis is lacking. In this study, we demonstrate ...
Psyrri Amanda - - 2004
Repression of the endogenous human papillomavirus (HPV) type 18 E7 gene in HeLa cervical carcinoma cells by the bovine papillomavirus E2 transcription factor activates the retinoblastoma (Rb) pathway and induces cells to undergo senescence. To determine whether activation of the Rb pathway is responsible for senescence in response to HPV18 ...
Bechter Oliver E - - 2004
Instead of telomerase, some immortal cells use the alternative lengthening of telomeres pathway (ALT) to maintain their telomeres. There is good evidence that homologous recombination contributes to the ALT mechanism. Using an inducible GFP reporter system to measure the frequency of homologous recombination, we asked whether or not ALT cells ...
Walen Kirsten H - - 2004
Previously, it was shown that SV40-induced cell transformation of human diploid (2N), epithelial cells was a dynamic process of nuclear and cellular events. In this process, nuclei of polyploid (above 2N) cells broke down into multinucleated cells (MNCs) by amitotic division. An induced mass karyoplast (i.e., small cell with reduced ...
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