Search Results
Results 601 - 650 of 1460
< 8 9 10 11 12 13 14 15 16 17 18 >
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 ...
Munro June - - 2004
We show here that histone deacetylase inhibitors (HDACIs) sodium dibutyrate (SDB) and trichostatin A (TSA) induce a phenotype that has similarities to replicative senescence in human fibroblasts. There was no evidence that SDB accelerated a constitutive cell division counting mechanism as previously suggested because cells pretreated with SDB for three ...
Shammas Masood A - - 2004
BACKGROUND & AIMS: Barrett's esophageal adenocarcinoma (BEAC) is a complication of gastroesophageal reflux disease, with no effective chemotherapy and poor prognosis. BEAC cells, like many other types of cancers, may reactivate telomerase to achieve unlimited proliferative potential, making telomerase a unique therapeutic target. The purpose of this study was to ...
Bakalova Rumiana - - 2004
PURPOSE: To clarify the role of the pathways dependent on protein-kinase C (PK-C) and Ca2+/calmodulin (CaM) in the regulation of telomerase activity in Burkitt's lymphoma cells. METHODS: Burkitt's lymphoma cells (Raji and Daudi) were treated with the PK-C inhibitor, bisindolylmaleimide (BIM), or the CaM inhibitor, trifluoperazine (TFPZ), in a dose-dependent ...
Satoh, Akiko
Replicative senescence (RS) of human diploid fibro blasts (HDFs) has become a classical model of aging and HDFs, such as WI-38 cells, display increased cellular oxidant production associated with RS. Several phenomena associated with RS are also observed in stress-induced replicative senescence (SIPS). In particular, SIPS of WI-38 cells caused ...
Pesah Yakov - - 2004
Mutations in the gene parkin in humans (PARK2) are responsible for a large number of familial cases of autosomal-recessive Parkinson disease. We have isolated a Drosophila homolog of human PARK2 and characterized its expression and null phenotype. parkin null flies have 30% lower mass than wild-type controls which is in ...
Thompson John E - - 2004
Regulation of protein synthesis is increasingly being recognized as an important determinant of cell proliferation and senescence. In particular, recent evidence indicates that eukaryotic translation initiation factor 5A (eIF-A) plays a pivotal role in this determination. Separate isoforms of eIF-5A appear to facilitate the translation of mRNAs required for cell ...
Maringele Laura - - 2004
Telomerase-defective budding yeast cells escape senescence by using homologous recombination to amplify telomeric or subtelomeric structures. Similarly, human cells that enter senescence can use homologous recombination for telomere maintenance, when telomerase cannot be activated. Although recombination proteins required to generate telomerase-independent survivors have been intensively studied, little is known about ...
Wang Kuan - - 2004
BACKGROUND: Peptide nucleic acid (PNA) has many characteristics useful in molecular biology. This paper described an effective way to raise the cell ingestion rate of PNA so as to kill gastric cancer cells. METHODS: Heteroduplexes of PNAs and oligonucleotides, wrapped by Lipofectamine 2000, were used to infect SGC7901 cells. The ...
Luo Ping - - 2004
Human diploid fibroblasts (HDF) rarely, if ever, undergo spontaneous transformation to an immortalized cell type. Here we report the immortalization of an HDF cell line following transduction with cyclin A2 or cdk1 human genes via retroviral vectors. Fluorescence in situ hybridization (FISH) studies using the retroviral vector as a probe ...
Villa Ana - - 2004
Human Neural Stem Cells (hNSCs) are excellent candidates for in vitro and in vivo molecular, cellular, and developmental research, and also for ex-vivo gene transfer and cell therapy in the nervous system. However, hNSCs are mortal somatic cells, and thus invariably enter an irreversible growth arrest after a finite number ...
Samokhvalov Victor - - 2004
Glycogen and trehalose are well known to participate in many important cell functions, e.g., protection from stress factors, regulation of cell growth and division, spore formation. Since the aging is a complex process involving many aspects of cell metabolism, it was interesting to study the role of glycogen and trehalose ...
Ojima Mitsuaki - - 2004
We examined the delayed induction of telomere instability in hTERT-immortalized normal human fibroblast (BJ1-hTERT) cells exposed to X-rays. BJ1-hTERT cells were irradiated with 2 Gy of X-rays, and chromosome aberrations were analyzed 24 hours after irradiation and in the surviving cells 14 days after X-ray exposure. We found that the ...
Narita Masashi - - 2004
Senescence is a permanent form of cell cycle arrest that limits the proliferation of damaged cells and may contribute to tumor suppression and aging. We recently demonstrated that some senescent cell types undergo dramatic changes in chromatin organization that are dependent on the retinoblastoma protein and are associated with the ...
Shen Zhong-Ying - - 2004
To investigate the multistage process of carcinogenesis, the progressive alteration of the morphology, telomerase, cytogenesis, oncogenes and tumorigenicity in the process of immortalization and malignant transformation of the human fetal esophageal epithelial cell (SHEE) was studied. The SHEE cells were immortalized by gene E6E7 of human papilloma virus (HPV) type ...
Nakatake M - - 2004
Telomerase is active in immature somatic cells, but not in differentiated cells. However, the mechanism by which telomerase is regulated in relation to cell differentiation is not well understood. In this study, the human erythroid leukemia cell line K562 was induced to differentiate into megakaryocytes by TPA and into erythroid ...
Gordy Claire - - 2004
Glycolipid-enriched membrane (GEM) domains, or lipid rafts, function in signaling in immune cells, but their properties during Ag presentation are less clear. To address this question, GEM domains were studied using fluorescence cell imaging of mouse CH27 B cells presenting Ag to D10 T cells. Our experiments showed that APCs ...
Colitz C M H - - 2004
Telomerase is a ribonucleoprotein complex responsible for maintaining the ends of chromosomes and for repair of DNA strand breaks. While telomerase activity is generally found in cells that have unlimited proliferative potential such as neoplastic cells, germline cells and some stem cells, lens epithelial cells (though not highly proliferative) have ...
Kocki Janusz - - 2004
Telomeres are the end fragments of chromosomes formed by a number of non-coding double-stranded TTAGGG repeats in vertebrates. During cell division the number of repeats decreases, leading to cell senescence or apoptosis. In immortal cells, including cancer cells, the telomere length is stable and maintained by, among other factors, telomerase. ...
< 8 9 10 11 12 13 14 15 16 17 18 >