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Blazić T Manestar TM Department of Dermatovenerology, Rijeka Medical School and University Hospital Center, Kresimirova 42, 510000 Rijeka, Croatia. - - 2006
Keloids are a hyperproliferative response of connective tissue in response to trauma. The mechanism by which this occurs is poorly understood and currently no successful treatment exists. Senescent fibroblasts form during wound repair, as the result of oxidative stress. They have a major role in the control of fibroblast proliferation ...
Lindkvist Anna - - 2005
The aim of the present study was to investigate the effect of transforming growth factor-beta1 (TGF-beta1) on telomerase activity in a panel of human anaplastic thyroid carcinoma (ATC) cell lines. Addition of TGF-beta1 decreased the telomerase activity in HTh 74 and KTC-1 cells, while in C 643 and HTh 7 ...
Gunduz Cumhur - - 2005
Propolis is a resinous substance which is used by bees to repair and maintain their hives. It has more than 180 compounds including flavonoids, phenolic acids and its esters which have anti-inflammatory, antibacterial, antiviral, immunomodulatory, antioxidant and antiproliferative effects. Propolis is shown to inhibit cell division and protein synthesis. However ...
Potter Alan J - - 2005
BACKGROUND: Telomeres shorten during DNA replication; extensive erosion of telomeres likely promotes replicative senescence and chromosomal instability. Telomere length in individual cells has been quantified by flow cytometric analysis of fluorescence in situ hybridization (flow-FISH). To determine the rate of telomere attrition (telomere erosion per cell division), we combined flow-FISH ...
Trimborn Marc - - 2005
Autosomal recessive primary microcephaly (MCPH) is a rare neurodevelopmental disorder characterized by mental retardation and congenital microcephaly with a head circumference at least 4 SD below age and sex means, in the absence of other significant malformations or neurological deficits. Truncating alterations in the MCPH1 gene have previously been shown ...
Park Woo-Chan - - 2005
Telomerase, a ribonucleoprotein enzyme that functions as a reverse transcriptase, is detected exclusively in immortal cells such as germ cells, stem cells and cancer cells. Telomerase activity is present in almost all human cancers. Telomerase activation is considered to be essential to maintain the integrity of the replicating tumor cell ...
Wick U - - 2005
The nucleo-protein structure of an intact telomere protects each chromosome from being recognized as a break and subsequently being degraded. The DNA component of this structure, the telomeric repeats, undergo attrition with every cell division, as well as in response to endogenous events, like oxidative stress. Exposure to exogenous damage ...
Tkemaladze J V - - 2005
The centrosome (centriole) and the cytoskeleton produced by it are structures, which probably determine differentiation, morphogenesis, and switching on the mechanism of replicative aging in all somatic cells of multicellular animals. The mechanism of such programming of the events seems to include cytoskeleton influences and small RNAs related to the ...
Kil In Sup - - 2006
The free radical hypothesis of aging postulates that senescence is due to an accumulation of cellular oxidative damage, caused largely by reactive oxygen species that are produced as by-products of normal metabolic processes. Recently, we demonstrated that the control of cytosolic and mitochondrial redox balance and the cellular defense against ...
Chagnon Pierre - - 2005
X-inactivation is a random process that occurs in females early during embryogenesis. Females are mosaics with an equal proportion of cells with the paternal (Xp) or maternal X-chromosome (Xm) in the active state. However, close to 40% of healthy females aged more than 60 y.o. present a significant skewing of ...
Viola Maria - - 2005
Bovine seminal-ribonuclease (BS-RNase) is a member of the 'ribonucleases with special biological actions' family since it possesses specific anti-tumour, anti-spermatogenic and embryotoxic activities and exerts an immunosuppressive effect on T lymphocytes. In previous studies it was demonstrated that BS-RNase induced apoptosis in proliferating, malignant and normal cells and that telomerase ...
Sadighi Akha Amir A - - 2005
T cells from aged mice show defects in the early stages of the activation process, including alterations in cytoskeletal reorganization that precede discrimination, by the T cell receptor, of agonist from antagonist peptides. Aging also modifies the pattern of glycosylation of T cell surface macromolecules, and enzymatic cleavage of these ...
Hao Zhi-Ming - - 2005
Restoration of telomerase activity is essential for most of the malignancies. Telomerase reverse transcriptase (TERT) is the key component of telomerase. In this study, we designed a hammerhead ribozyme against human telomerase reverse transcriptase (hTERT) and observed its growth inhibition and pro-apoptosis effects on cancer cells. The efficiency of this ...
Vigneron Arnaud - - 2005
DNA-damaging drugs stop tumor cell proliferation by inducing apoptosis, necrosis, or senescence. Cyclin-dependent kinase inhibitor p21waf1 is an important regulator of these responses, promoting senescence and preventing aberrant mitosis that leads to cell death. Because tumors expressing oncogenic tyrosine kinases are relatively resistant to DNA-damaging agents, the effects of Src ...
Gupta Sudhir - - 2006
Aging in humans is associated with progressive decline in T cell function, hyperimmunoglobulinemia, increased prevalence of autoantibodies and decline in naïve CD8(+) T cells and accumulation of memory T cells, which appears to be oligoclonal and display feature of senescence, that is, decreased replication, short telomere length and resistance to ...
Chang Martina Wei-Fen - - 2005
The need for standardized experimental conditions to gain relevant and reproducible results has increased the demand for well characterized continuously growing cell lines that exhibit the characteristics of their normal counterparts. Immortalization of normal human cells by ectopic expression of the catalytic subunit of human telomerase (hTERT) has shown to ...
Porzionato Andrea - - 2006
We studied by immunocytochemistry the expression of AM in human carotid bodies, sampled at autopsy from 16 adult subjects (mean age+/-S.D.: 44.3+/-3.4 years) and from six fetuses (mean gestational age+/-S.D.: 167+/-11 days). No AM immunoreactivity was visible in the type II cells of both series. The percentage of immunoreactive type ...
Carter R T - - 2005
Paraffin wax-embedded ocular globes of cats with post-traumatic ocular sarcomas were examined for the presence of TERT, the active subunit of telomerase. The latter is a ribonucleoprotein complex essential for immortalization and expressed by most malignant tumours, germ line cells, lens epithelial cells, and some stem cells. Due to the ...
Yang Nae-Cherng - - 2005
The senescence associated-beta-galactosidase (SA-betaG) assay has become one of the most commonly used markers of cell-aging. However, the reliability of the assay is questionable because the enzyme is a non-specific marker for cell-aging. In this study, we found that the SA-betaG activity increased with cell age as well as in ...
Crea Francesco - - 2006
The enzyme telomerase plays a crucial role in cellular proliferation. By adding hexameric repeats to the chromosome ends, it prevents telomeric loss and, thus entry into senescence of limited life span cells. It is unclear, however, what would be the effect of over-expressing telomerase in an immortalised cell line, characterised ...
Wright Woodring E - - 2005
It is thought that a limited investment by the body in many types of maintenance and repair causes aging. Cell turnover is one mechanism of replacing damaged cells, and cell division thus contributes to good repair, but the number of times cells can divide is limited to form a barrier ...
Chau Nguyen Phong - - 2005
BACKGROUND: Clinical and experimental observations indicate that resistance to anticancer drugs may be spontaneously reversible over time. MATERIALS AND METHODS: This work is a mathematical and statistical analysis of the relationship, during a 9-month experiment, between the resistance of repeatedly re-seeded hepatoma cells to methotrexate (MTX) or to cisplatin (cisP) ...
Raices Marcela - - 2005
The nematode Caenorhabditis elegans, after completing its developmental stages and a brief reproductive period, spends the remainder of its adult life as an organism consisting exclusively of post-mitotic cells. Here we show that telomere length varies considerably in clonal populations of wild-type worms, and that these length differences are conserved ...
Crowe David L - - 2005
Stratified squamous epithelial cells undergo an orderly process of cell cycle arrest following detachment from the basement membrane. The basal layer cells which adhere to the basement membrane express telomerase, which maintains the ends of chromosomes in this rapidly dividing population. Non-dividing suprabasal cells downregulate telomerase activity. However, the mechanisms ...
Katakura Yoshinori - - 2005
We investigated the effects of a sublethal concentration of H(2)O(2) on cancer cells by using sublines derived from human lung adenocarcinoma cell line A549 cells exposed to 200 microM H(2)O(2). These sublines (AST cells) showed an elongated morphology distinct from the rounded morphology of A549 cells. Notably, AST cells demonstrated ...
O'Sullivan Jacintha N - - 2005
Telomeres are repetitive DNA sequences at the end of each chromosome that provide stability and prevent end-to-end chromosome fusions. In order to understand mechanisms responsible for telomere shortening, it is necessary to develop methods for accurate telomere length measurement that can be applied to archival and fresh tissue and cells. ...
Burke Janice M - - 2005
The retinal pigment epithelium (RPE) is a monolayer of cells that appear phenotypically regular, but which exhibit striking cell-cell variability in content of melanin and lipofuscin granules, and in expression of many proteins. This naturally occurring cell heterogeneity likely arises by normal mechanisms regulating gene expression during development and postnatal ...
Wang Zhen - - 2005
PURPOSE: Extracellular matrix (ECM) plays an important role in the regulation of cell function. The aging process may involve chemical modifications to ECM proteins, which may contribute to the aging of the Bruch membrane and pathogenesis of age-related macular degeneration (AMD). The purpose of this study is to investigate nitrite ...
Arlotta Paola - - 2005
Defining the life span of specific human cell populations is limited by our inability to mark the exact time when cells are born in a way that can be detected over many years. In this issue of Cell, Spalding et al. (2005) describe a clever strategy for retrospectively birth dating ...
Wang Yisong - - 2005
Telomerase deficiency leads to a progressive loss of telomeric DNA that eventually triggers cell apoptosis in human primary cells during prolonged growth in culture. Rare survivors can maintain telomere length through either activation of telomerase or recombination-based telomere lengthening, and thus proliferate indefinitely. We have explored the possibility that telomeres ...
Cabuy E - - 2005
We examined telomere maintenance in cells of 11 primary fibroblast cell lines with differing genetic defects that confer sensitivity to ionizing radiation. These included cell lines derived from patients with ataxia telangiectasia, Nijmegen breakage syndrome, Fanconi anemia, defective Artemis, DNA ligase I and DNA ligase IV, an immunodeficient patient with ...
Bortolanza S - - 2005
The promoter for human telomerase reverse transcriptase (hTERTp) is preferentially active in malignant cells. It was recently used to control the expression of the adenoviral E1A gene for the development of oncolytic adenoviruses. To ensure maximal repression in normal cells, the inclusion of additional E-boxes in the proximal region of ...
Wick U - - 2005
Damage to telomeres induced by cytostatic therapy theoretically could generate telomere shortening and, subsequently, induce an additional genomic instability in neoplastic cells. Model experiments were carried out to examine this hypothesis. Cells of the T-ALL derived cell line CCRF-CEM were exposed to various different concentrations of Bleomycin (BLM) or Mitomycin ...
Hathcock Karen S - - 2005
Extract: In the 1960s Hayflick reported that normal human somatic cells have a finite replicative capacity and that, after a limited number of cell divisions, cells no longer divide and enter a state termed senescence. Since this observation was made, considerable research energy has focused on identifying molecular pathways that ...
Jones K R - - 2005
Ionizing radiation has been reported to promote accelerated or premature senescence in both normal and tumour cell lines. The current studies were designed to characterize the accelerated senescence response to radiation in the breast tumour cell in terms of its dependence on functional p53 and its relationship to telomerase activity, ...
Passos João F - - 2005
The accumulation of oxidative damage is one of the most widely accepted causes of ageing. Mitochondrial dysfunction, in particular damage to the mitochondrial DNA has been hypothesised, more than thirty years ago, as responsible for increased production of reactive oxygen species (ROS) and, thus, as one possible causal factor for ...
Aydos Sena E - - 2005
The mechanism of final cessation of the reproductive life span has not been solved yet. It is generally assumed that the most important factor is ovarian follicular reserve. In ovaries at intrauterine period, a major factor that determines the number of the primordial follicle is the mitotic ability as well ...
Shariftabrizi Ahmad - - 2005
BACKGROUND: The level of activity of the telomerase has been shown to correlate with the degree of invasiveness in several tumor types. In addition, cellular redox state is believed to regulate the secretion of matrix metalloproteinase-2 (MMP-2). AIMS: To determine the effect of anti-sense telomerase treatment of prostate cancer cells ...
Satoh Rie - - 2005
We have previously reported that sodium fluoride (NaF) showed slightly higher cytotoxicity against human oral tumor cell lines than normal human oral cells. Possible changes in the NaF sensitivity of three normal human oral cell types (gingival fibroblast HGF, pulp cell HPC, periodontal ligament fibroblast HPLF) during in vitro ageing ...
Di Felice Valentina - - 2005
Normal mammalian fibroblasts cultured in vitro undergo a limited number of divisions before entering a senescent phase in which they can be maintained for long periods but cannot be induced to divide. Senescent cells become unresponsive to growth-promoting signals and exhibit senescent cell morphology with flattened and enlarged cell shape. ...
Malanga M - - 2005
Protein modification by ADP-ribose polymers is a common regulatory mechanism in eukaryotic cells and is involved in several aspects of brain physiology and physiopathology, including neurotransmission, memory formation, neurotoxicity, ageing and age-associated diseases. Here we show age-related misregulation of poly(ADP-ribose) synthesis in rat cerebellum as revealed by: (i) reduced poly(ADP-ribose) ...
Franco Sonia - - 2005
Critical telomere shortening in the absence of telomerase in late generation Terc-/- mice (G3 Terc-/-) or loss of telomere capping due to abrogation of the DNA repair/telomere binding protein Ku86 (Ku86-/- mice) results in telomere dysfunction and organismal premature aging. Here, we report on genome-wide transcription in mouse G3 Terc-/-, ...
Nicole Denise Guzmán Blastervold, ...
Eukaryotic organisms package their genetic material into linear chromosomes. Telomeres are the ends of linear chromosomes and consist of terminal G-rich repetitive sequences. These structures play a key role in genetic stability protecting chromosome ends from degradation and end-to-end fusions. Telomeres are maintained by the specialized enzyme reverse transcriptase telomerase. ...
Kichey Thomas - - 2005
In order to improve our understanding of the regulation of nitrogen assimilation and recycling in wheat (Triticum aestivum L.), we studied the localization of plastidic (GS2) and cytosolic (GS1) glutamine synthetase isoenzymes and of glutamate dehydrogenase (GDH) during natural senescence of the flag leaf and in the stem. In mature ...
Marciniak Robert A - - 2005
Cancer cells require mechanisms to maintain telomeres. Most use telomerase, but 5% to 20% of tumors use alternative lengthening of telomeres (ALT), a telomerase-independent mechanism that seems to depend on recombination. ALT is characterized by amplification of telomere TTAGGG repeats to lengths beyond 50 kb, by elevated rates of telomere ...
Nagao Kumi - - 2005
Normal human liver cells have a limited capacity for proliferation due to telomere shortening, whereas immortalized cells prevent shortening of the 3' single strand telomeric repeat by expressing telomerases, including human telomerase reverse transcriptase (hTERT). The hTERT transcript contains three deletion sites that give rise to alternatively spliced variants (ASVs). ...
Gorgoulis Vassilis G - - 2005
Most normal somatic cells enter a state called replicative senescence after a certain number of divisions, characterized by irreversible growth arrest. Moreover, they express a pronounced inflammatory phenotype that could contribute to the aging process and the development of age-related pathologies. Among the molecules involved in the inflammatory response that ...
Fasching Clare L - - 2005
Immortal tumor cells and cell lines employ a telomere maintenance mechanism that allows them to escape the normal limits on proliferative potential. In the absence of telomerase, telomere length may be maintained by an alternative lengthening of telomeres (ALT) mechanism. All human ALT cell lines described thus far have nuclear ...
Fabre Stéphanie - - 2005
We have previously reported at the single cell level that PI3K is activated after conjugate formation between T lymphocytes and APCs. However, in contrast to cells exposed to an asymmetrical signal that usually increase 3'-phosphoinositides (3'-PI) transiently in the region of the activated receptors, T cells contacting APC accumulate 3'-PI ...
Karpinets Tatiana V - - 2005
Recent studies indicate that during tumorigenic transformations, cells may generate mutations by themselves as a result of error-prone cell division with participation of error-prone polymerases and aberrant mitosis. These mechanisms may be activated in cells by continuing proliferative and survival signaling in a sustained stress environment (SSE). The paper hypothesizes ...
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