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Traps
Kinds of Traps Terms modified by Traps Selected AbstractsEffect of weather factors on populations of Helicoverpa armigera moths at cotton-based agro-ecological sitesENTOMOLOGICAL RESEARCH, Issue 1 2009Ghulam Mustafa AHEER Abstract Pheromone trapping was used to monitor populations of the moth Helicoverpa armigera at five cotton-based agro-ecological sites , river, vegetable, orchard, forest and clean cultivation (areas under only cotton cultivation) , in the Bahawalpur district, Pakistan. Three locations at each site were chosen and three pheromone traps at each location were installed in cotton fields. Moth catches were recorded at 15,20 day intervals from 24 October 2004 to 19 December 2006. In 2004, the river sites showed the maximum trapped population of H. armigera (0.22/trap) followed by 0.165 per trap at the vegetable sites. Orchard, clean cultivation and forest sites had zero moth catches. In 2005, the river sites again showed the highest trapped population (0.57/trap), followed by clean cultivation (0.45/trap), vegetable (0.44/trap), orchard (0.40/trap) and forest (0.29/trap). The moths appeared during July to December and March to May. In 2006, sites showed non-significant difference, with a population range of 0.47 to 0.97 moths per trap. On average, river sites peaked at 0.49 per trap, followed by vegetable (0.38), clean cultivation (0.47), orchard (0.35) and forest (0.25) sites. The peak was observed on 3 April 2006, and moths appeared during February to July and October to December. The minimum temperature in river, forest and clean cultivation sites; the maximum temperature in orchard sites; and the average temperature in river, orchard, forest and clean cultivation sites showed significant positive correlations with trapped moth populations. Relative humidity showed significant negative correlation with population at the orchard sites in 2005. All weather factors during 2004 and 2006 showed non-significant correlations with the moth populations. No model was found to be best fit by multiple linear regression analysis; however, relative humidity, minimum temperature, maximum temperature, minimum temperature and maximum temperature contributed 8.40, 10.23, 2.43, 4.53 and 2.53% to the population fluctuation of the moth at river, vegetable, orchard, forest and clean cultivation sites, respectively. [source] Plasmodium falciparum: binding studies of peptide derived from the sporozoite surface protein 2 to Hep G2 cellsCHEMICAL BIOLOGY & DRUG DESIGN, Issue 4 2001R. López Abstract:Plasmodium falciparum sporozoite surface protein 2 (Pf SSP2), also called thrombospondin related anonymous protein (TRAP), is involved in the process of sporozoite invasion of hepatocytes. Pf SSP2/TRAP possesses two different adhesion domains sharing sequences and structural homology with von Willebrand factor A-domains and human repeat I thrombospondin (TSP). Pf SSP2/TRAP has also been implicated in sporozoite mobility and in mosquito salivary gland invasion processes. We tested 15-mer long synthetic peptides having five overlapping residues covering the complete protein Pf SSP2 sequence in binding assays to Hep G2 cells. In these 57 peptides, 21 high-activity binding peptides (HABPs) were identified; five were in the adhesion domains already described and 16 were in two regions toward the protein's carboxy and middle terminal part. Six HABPs showed conserved amino acid sequences: 3243 (21FLVNGRDVQNNIVDE35), 3279 (201FLVGCHPSDGKCNLY215), 3287 (241TASCGVWDEWSPCSV255), 3289 (251SPCSVTCGKGTRSRK265), 3327 (441ERKQSDPQSQDNNGNY455) and 3329 (451DNNGNRHVPNSEDREY465). The HABPs show saturable binding and dissociation constants between 140 and 900 nm with 40,000,855 000 binding sites per cell. The 3279 (201FLVGCHPSDGKCNLY215), 3323 (421NDKSDRYIPYSPLSP435) and 3331 (461SEDRETRPHGRNNENY475) HABPs have B epitopes in their sequences; these have previously been recognized by antibodies partially inhibiting hepatocyte invasion and development of the hepatic state. The 3287 (241TASCGVWDEWSPCSV255) and 3289 (251SPCSVTCGKGTRSRK265) HABPs share common sequences with the Pf SSP2/TRAP region II plus, which is present in a great number of adhesion proteins. Based on this information, six new peptides covering the high binding regions identified previously were synthesized and, using a competition assay, the amino acid involved in the binding were determined. [source] Increased circulating platelet,leukocyte aggregates in myeloproliferative disorders is correlated to previous thrombosis, platelet activation and platelet countEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 3 2001Morten Krogh Jensen Abstract: Platelet,leukocyte adhesion may occur as a consequence of platelet activation and possibly plays a key role in the deposition of activated platelets and fibrin in the thrombotic plug. The aim of the present study was to assess by whole blood flow cytometry the presence of circulating platelet,leukocyte aggregates (PLA) and the platelet,leukocyte response to platelet agonist stimulation (ADP and TRAP) in 50 patients with chronic myeloproliferative disorders (MPD) and 30 controls. PLA were identified as platelet,granulocyte/monocyte aggregates (PGMA), platelet,monocyte aggregates (PMA) and defined as the percentage of leukocytes coexpressing the platelet-specific marker glycoprotein Ib. Compared to controls the mean percentage of PGMA and PMA was increased in unstimulated whole blood from patients with MPD (7.98 vs. 1.76%; p<0.001 and 12.34 vs. 3.2%; p<0.001, respectively). The percentage of PGMA was correlated to the platelet count (r=0.46; p<0.001), percentage of P-selectin (r=0.69; p<0.001) and thrombospondin (r=0.58; p<0.001) positive platelets and platelet expression of GPIV (r=0.33; p=0.02). The mean percentage of PGMA and PMA was significantly increased in ADP-stimulated whole blood of patients (57.14 vs. 47.92%; p=0.009 and 54.91 vs. 45.89%; p<0.001, respectively). Compared to patients without a history of thrombosis, patients having experienced microvascular disturbances or a thrombotic event had a higher mean percentage of PGMA and PMA in non-stimulated whole blood (10.07 vs. 6.34%; p=0.025 and 14.81 vs. 10.48%; p=0.021, respectively) and a higher percentage of PGMA in ADP stimulated whole blood (64.32 vs. 51.50%; p<0.01). These data document an increased frequency of PLA in non-stimulated whole blood in MPD associated with a previous history of thrombosis or microvascular disturbances. [source] Reduced growth hormone receptor immunoreactivity in osteoclasts adjacent to the erupting molar in the incisor-absent (osteopetrotic) ratEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2003Anne L. Symons First molars fail to erupt in the incisor-absent (ia/ia) rat because of a defect in osteoclast function. Growth factors that regulate local bone metabolism include growth hormone (GH), insulin-like growth factor-I (IGF-I), epidermal growth factor (EGF) and interleukin-1 alpha (IL- 1,). Since osteoclast function may be affected by these factors, the aim of this study was to determine the distribution of GH receptor (GHr), IGF-I, EGF and IL-1,, in osteoclasts located occlusal to the erupting first molar, in the ,eruption pathway', in normal and ia/ia rats. Sagittal sections of the first molar and adjacent bone from 3- and 9-d-old animals were examined. Osteoclasts were identified using tartrate-resistant acid phosphatase (TRAP). The TRAP-positive osteoclast cell numbers were higher in ia/ia animals at 3 and 9 days-of-age. In the ia/ia group, fewer osteoclasts were GHr- and IGF-I-positive at 3 d of age, and at 9 d of age fewer osteoclasts were GHr-positive. In the ia/ia rat, defective osteoclast function failed to resorb bone to provide an eruption pathway for the lower first molar. The expression of GHr, and to some degree IGF-I, by these osteoclasts was reduced, which may be related to their ability to differentiate and function. [source] Bumetanide, the Specific Inhibitor of Na+ -K+ -2Cl, Cotransport, Inhibits 1,,25-Dihydroxyvitamin D3 -Induced Osteoclastogenesis in a Mouse co-culture SystemEXPERIMENTAL PHYSIOLOGY, Issue 5 2003Hyun-A Lee The Na+ -K+ -2Cl, cotransporter (NKCC1) is responsible for ion transport across the secretory and absorptive epithelia, the regulation of cell volume, and possibly the modulation of cell growth and development. It has been reported that a variety of cells, including osteoblasts, contain this cotransporter. In this study, the physiological role of NKCC1 in osteoclastogenesis was exploited in a co-culture system. Bumetanide, a specific inhibitor of NKCC1, reduced the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells. In order to investigate the mechanism by which bumetanide inhibits osteoclastogenesis, the mRNA expressions of the receptor activator of nuclear factor (NF)-,B ligand (RANKL) and osteoprotegerin (OPG) were analysed by RT-PCR. Exposure of osteoblastic cells to a medium containing 1 µM bumetanide reduced RANKL mRNA expression induced by 10 nM 1,,25-dihydroxyvitamin D3 (1,,25(OH)2D3, in a dose-dependent manner. In addition, RANKL expression was also analysed with enzyme-linked immunosorbant assay (ELISA) using anti-RANKL antibody. The expression of RANKL was decreased with the increase of bumetanide concentration. In contrast, the expression of OPG mRNA, a novel tumour necrosis factor (TNF) receptor family member was increased in the presence of bumetanide. These results imply that bumetanide inhibits osteoclast differentiation by reducing the RANKL/OPG ratio in osteoblastic cells. However, no significant difference in M-CSF mRNA expression was observed when bumetanide was added. Also, we found that the phosphorylation of c-Jun NH2 -terminal kinase (JNK), which regulates the activity of various transcriptional factors, was reduced by bumetanide treatment. Conclusively, these findings suggest that NKCC1 in osteoblasts has a pivotal role in 1,,25(OH)2D3 -induced osteoclastogenesis partly via the phosphorylation of JNK. [source] The tripartite ATP-independent periplasmic (TRAP) transporters of bacteria and archaeaFEMS MICROBIOLOGY REVIEWS, Issue 4 2001David J Kelly Abstract Until recently, extracytoplasmic solute receptor (ESR)-dependent uptake systems were invariably found to possess a conserved ATP-binding protein (the ATP-binding cassette protein or ABC protein), which couples ATP hydrolysis to the translocation of the solute across the cytoplasmic membrane. While it is clear that this class of ABC transporter is ubiquitous in prokaryotes, it is now firmly established that other, unrelated types of membrane transport systems exist which also have ESR components. These systems have been designated tripartite ATP-independent periplasmic (TRAP) transporters, and they form a distinct class of ESR-dependent secondary transporters where the driving force for solute accumulation is an electrochemical ion gradient and not ATP hydrolysis. Currently, the most well characterised TRAP transporter at the functional and molecular level is the high-affinity C4-dicarboxylate transport (Dct) system from Rhodobacter capsulatus. This consists of three proteins; an ESR (DctP) and small (DctQ) and large (DctM) integral membrane proteins. The characteristics of this system are discussed in detail. Homologues of the R. capsulatus DctPQM proteins are present in a diverse range of prokaryotes, both bacteria and archaea, but not in eukaryotes. The deduced structures and possible functions of these homologous systems are described. In addition to the DctP family, other types of ESRs can be associated with TRAP transporters. A conserved family of immunogenic extracytoplasmic proteins is shown to be invariably associated with TRAP systems that contain a large DctQM fusion protein. All of the currently known archaeal systems are of this type. It is concluded that TRAP transporters are a widespread and ancient type of solute uptake system that transport a potentially diverse range of solutes and most likely evolved by the addition of auxiliary proteins to a single secondary transporter. [source] Malaria sporozoite antigen-directed genome-wide response in transgenic Drosophila,GENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 3 2009Jizhou Yan Abstract Malaria kills a million people annually. Understanding the relationship between a causative parasite, Plasmodium falciparum, and the mosquito vector might suggest novel prevention approaches. We created and transformed into Drosophila two genes encoding, thrombospondin-related adhesive protein (TRAP) and circumsporozoite protein (CSP), found on the cell surface of Plasmodium sporozoites. To understand a model insect's response, we induced these proteins separately and together, performing whole genome microarray analysis measuring gene expression changes. Gene ontology classification of responding genes reveals that TRAP and CSP strongly and differentially influence Drosophila genes involved with cell motility and gene regulation, respectively; however, the most striking effects are on the immune system. While immune-related genes are but modestly elevated compared with responses to sepsis, there is a marked repression of the Toll pathway. This suggests: (1) how Plasmodium infection of the mosquito might use TRAP and CSP to modulate the host insect's physiology to promote sporozoite survival and transmission to man and (2) that approaches to elevate expression of the mosquito's Toll pathway might lead to novel methods of malaria prevention. genesis 47:196,203, 2009. © 2009 Wiley-Liss, Inc. [source] Telomerase activity and hTERT mRNA expression can be heterogeneous and does not correlate with telomere length in soft tissue sarcomasINTERNATIONAL JOURNAL OF CANCER, Issue 6 2002Pu Yan Abstract In a previous study, we showed that telomerase activity (TA) and human telomerase reverse transcriptase (hTERT) mRNA expression were undetectable in benign mesenchymal lesions and low-grade soft tissue sarcomas (STSs), but detectable in about 50% of intermediate-/high-grade STSs. We wondered if this lack of TA or hTERT mRNA expression could be related to the tumor sample examined and if there was a relationship between the former 2 parameters and telomere length. Two separate tumor samples from 37 STSs were examined for telomerase activity, using the telomerase repeat amplification protocol (TRAP) assay and for hTERT mRNA expression, using RT-PCR. Telomere length was determined in each tumor sample, using the terminal restriction fragments (TRF) technique. Significant variations in telomere length, TA and hTERT mRNA expression between 2 samples of the same tumor were observed in 27%, 11% and 27% of STSs, respectively. Telomere length did not correlate with TA or hTERT mRNA expression. Despite great intratumoral heterogeneity in telomere length, short and long telomeres were more often seen in the low/intermediate-grade and high-grade STS categories, respectively. Few STSs that showed a TRF pattern suggestive of alternative lengthening of telomeres (ALT) may contain ALT subpopulations. © 2002 Wiley-Liss, Inc. [source] Dynamic Addressing of a Surface Pattern by a Stimuli-Responsive Fusion Protein,ADVANCED MATERIALS, Issue 3 2003W. Frey Thermodynamically reversible addressing of proteins (TRAP) is demonstrated. A stimuli-responsive elastin-like polypeptide fused to thioredoxin is used to reversibly address the fusion protein onto a chemically micropatterned surface template by switching the interaction between the surface and the stimuli- responsive polypeptide (see Figure). [source] Genistein induces cell growth inhibition in prostate cancer through the suppression of telomerase activityINTERNATIONAL JOURNAL OF UROLOGY, Issue 1 2005HIDEKI OUCHI Abstract Aim:, To clarify the mechanism of the anticancer effect of genistein, we examined the effect of genistein on telomerase activity in prostate cancer cells. We hypothesized that genistein may exert its anticancer effect by modifying telomerase activity in prostate cancer cells. Methods:, Prostate cancer (LNCaP) cells were cultured with genistein and the number of viable cells was counted. Growth medium was also collected to measure prostate-specific antigen (PSA) concentration. Polymerase chain reaction (PCR)-based telomeric repeat amplification protocol (TRAP) assay and reverse transcriptase (RT)-PCR analysis were performed to investigate telomerase activity and the expression of human telomerase reverse transcriptase (hTERT), c-myc and p21 mRNA. To examine the possibility that hTERT transcriptional activity is modulated by genistein, transient cell transfection studies were performed by using luciferase reporter assay. Telomere repeat amplification protocol (TRAP) assay and PCR analysis of hTERT were performed in androgen independent cells, DU-145. Results:, Cell growth of LNCaP was inhibited by genistein and PSA secretion was similarly reduced. In TRAP assay, the telomerase activity of LNCaP cells was reduced by genistein. Reverse transcriptase-PCR analysis revealed that the expression of hTERT and c-myc mRNA was down-regulated by genistein, whereas p21 mRNA increased in response to genistein. Luciferase reporter assay revealed that genistein reduced the transcriptional activity of hTERT. In DU-145 cells, telomerase activity and the expression of hTERT mRNA were also reduced by genistein. Conclusion:, The current study elucidated the molecular mechanism of cell growth inhibition by genistein. The antiproliferative effects of genistein seem to be exerted on the hTERT transcriptional activity via different molecular pathways. [source] Use of a Phage Display Technique to Identify Potential Osteoblast Binding Sites Within Osteoclast Lacunae,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 5 2002Tzong-Jen Sheu Abstract There is a temporal coupling between the processes of bone resorption and bone formation in normal skeletal remodeling. That is, osteoblastic activity usually follows episodes of osteoclastic activity. However, what has not been universally appreciated is that there also is a spatial coupling between these processes. Bone formation only occurs in the immediate vicinity of the resorptive event. In this study, we describe a phage display technique that has been used to identify the mechanisms by which osteoblasts recognize components of the prior resorbed lacunar surface. Using a type V tartrate-resistant acid phosphatase (TRAP) as the bait and a random peptide M13 phage display library as the probe, we have identified specific sequences that show a very high affinity for TRAP. One of these peptides, designated clone 5, has a subnanomolar Kd for TRAP, interacts with TRAP in a Far-Western assay, binds exclusively to TRAP within osteoclast lacunae, is present in osteoblasts, and can effectively block osteoblast binding to resorption surfaces. The clone 5 peptide shows a high homology to glypican 4 (GPC4), a proteoglycan attachment receptor found in a number of cell types. [source] Female Estrogen Receptor ,,/, Mice Are Partially Protected Against Age-Related Trabecular Bone LossJOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2001Sara H. Windahl Abstract Recently, it has been shown that inactivation of estrogen receptor , (ER-,) by gene targeting results in increased cortical bone formation in adolescent female mice. To study the possible involvement of ER-, in the regulation of the mature skeleton, we have extended the analyses to include 1-year-old ER-, knockout mice (ER-,,/,). Male ER-,,/, mice did not express any significant bone phenotypic alterations at this developmental stage. However, the increase in cortical bone parameters seen already in the adolescent female ER-,,/, mice was maintained in the older females. The aged female ER-,,/, mice further exhibited a significantly higher trabecular bone mineral density (BMD) as well as increased bone volume/total volume (BV/TV) compared with wild-type (wt) mice. This was caused by a less pronounced loss of trabecular bone during adulthood in female ER-,,/, mice. The growth plate width was unaltered in the female ER-,,/, mice. Judged by the expression of the osteoclast marker tartrate-resistant acid phosphatase (TRAP) and cathepsin K (cat K; reverse-transcription-polymerase chain reaction [RT-PCR]) as well as the serum levels of C-terminal type I collagen cross-linked peptide, bone resorption appeared unaffected. However, an increase in the messenger RNA (mRNA) expression levels of the osteoblast marker core-binding factor ,1 (Cbfa1) suggested an anabolic effect in bones of old female ER-,,/, mice. In addition, the mRNA expression of ER-, was augmented, indicating a role for ER-, in the development of this phenotype. Taken together, the results show that ER-, is involved in the regulation of trabecular bone during adulthood in female mice and suggest that ER-, acts in a repressive manner, possibly by counteracting the stimulatory action of ER-, on bone formation. [source] Prostaglandin E2 Induces Expression of Receptor Activator of Nuclear Factor,,B Ligand/Osteoprotegrin Ligand on Pre-B Cells: Implications for Accelerated Osteoclastogenesis in Estrogen DeficiencyJOURNAL OF BONE AND MINERAL RESEARCH, Issue 7 2000Masahiro Kanematsu Abstract Estrogen deficiency causes bone loss as a result of accelerated osteoclastic bone resorption. It also has been reported that estrogen deficiency is associated with an increase in the number of pre-B cells in mouse bone marrow. The present study was undertaken to clarify the role of altered B lymphopoiesis and of the receptor activator of nuclear factor-,B ligand (RANKL), a key molecule in osteoclastogenesis, in the bone loss associated with estrogen deficiency. In the presence of prostaglandin E2 (PGE2), the activity to form tartrate-resistant acid phosphatase (TRAP)-positive osteoclast-like cells was significantly greater in bone marrow cells derived from ovariectomized (OVX) mice than in those from sham-operated mice. Northern blot analysis revealed that PGE2 increased the amount of RANKL messenger RNA (mRNA) in bone marrow cells, not only adherent stromal cells but nonadherent hematopoietic cells; among the latter, RANKL mRNA was more abundant in OVX mice than in sham-operated mice and was localized predominantly in B220+ cells. Flow cytometry revealed that most B220+ cells in bone marrow were RANKL positive and that the percentage of RANKL-positive, B220low cells was higher in bone marrow from OVX mice than in that from sham-operated mice. The increase in the expression of RANKL and the percentage of these cells in OVX mice was abolished by the administration of indomethacin in vivo. PGE2 also markedly increased both the level of RANKL mRNA and cell surface expression of RANKL protein in the mouse pre-B cell line 70Z/3. Finally, osteoclastogenic response to PGE2 was reduced markedly by prior depletion of B220+ cells, and it was restored by adding back B220+ cells. Taken together with stimulated cyclo-oxygenase (COX)-2 activity by tumor necrosis factor , (TNF-,) and interleukin-1 (IL-1) in estrogen deficiency, these results suggest that an increase in the number of B220+ cells in bone marrow may play an important role in accelerated bone resorption in estrogen deficiency because B220+ cells exhibit RANKL on the cell surface in the presence of PGE2, thereby leading to accelerated osteoclastogenesis. [source] Endogenous n-3 fatty acids protect ovariectomy induced bone loss by attenuating osteoclastogenesisJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 8b 2009Md Mizanur Rahman Abstract Beneficial effects of n-3 fatty acids (FA) on bone mineral density (BMD) have been reported in mice, rats and human beings, but the precise mechanisms involved have not been described. This study used the Fat-1 mouse, a transgenic model that synthesizes n-3 FA from n-6 FA to directly determine if outcome of bone health were correlated with n-3 FA. Ovariectomized (Ovx) and sham operated wild-type (WT) and Fat-1 mice were fed an AIN-93M diet containing 10% corn oil for 24 weeks. BMD was analysed by dual energy x-ray absorptiometry. Fat-1 Ovx mice exhibited significantly lower level of osteotropic factors like receptor activator of NF-,B ligand and tartrate-resistant acid phosphatase (TRAP)5b in serum and higher BMD in distal femoral metaphysis, proximal tibial metaphysis, femoral diaphysis and lumbar vertebra as compared to WT Ovx mice. LPS-stimulated bone marrow (BM) cells from Fat-1 Ovx mice produced significantly lower level of pro-inflammatory cytokines like tumour necrosis factor-,, interleukin (IL)-1-,, IL-6 and higher level of anti-inflammatory cytokines like IL-10, IFN-, and higher level of nitric oxide as compared to BM cells from WT Ovx mice. LPS-stimulated COX-II activity as well as NF-,B activation in BM cells from Fat-1 Ovx mice was significantly less as compared to BM cells from WT Ovx mice. Furthermore, Fat-1 BM cells generated significantly less number of TRAP osteoclast-like cells as compared to WT BM cells. In conclusion, we offer further insight into the mechanisms involved in preventing the BMD loss in Ovx mice by n-3 FA using a Fat-1 transgenic mouse model. [source] Phosphorylated osteopontin promotes migration of human choriocarcinoma cells via a p70 S6 kinase-dependent pathwayJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2005Rania Al-Shami Abstract This study examined the role of osteopontin (OPN), a phosphorylated secreted glycoprotein, in the promotion of trophoblastic cell migration, an early event in the embryo implantation process. Three human choriocarcinoma cell lines, namely JAR, BeWo, and JEG-3, were treated with variants of OPN differing in the extent of phosphorylation following sequential dephosphorylation with tartrate-resistant acid phosphatase (TRAP), and their migratory response was measured. The highly phosphorylated human milk form of OPN (OPN-1) strongly triggered migration in all three cell lines, whereas the less phosphorylated variants, OPN-2a and OPN-2b, failed to stimulate migration. JAR cell migration in response to OPN-1 was accompanied by a rapid rearrangement of actin filaments to the cellular membrane. Using broad spectrum protein kinase profiling, we identified p70 S6 kinase as a major signal transduction pathway activated by OPN-1 during the migratory response in JAR cells. Activation was blocked completely by rapamycin and LY294002, thus demonstrating that OPN-1-stimulated migration occurs through mTOR and PI3K pathways, respectively. Conversely, PD98059 did not affect the activation of p70 S6 kinase by OPN-1, therefore, this response does not involve the Ras/ MAPK signaling cascade. Together, these data show that the highly phosphorylated human OPN-1 can stimulate trophoblastic cell migration and provides evidence for the involvement of the PI3K/mTOR/p70 S6 kinase pathway in the JAR cells response. Because both OPN and TRAP are expressed in the uterus during early pregnancy, it is conceivable that extracellular phosphatases such as TRAP may modify OPN charge state and thus modulate cell migration. © 2005 Wiley-Liss, Inc. [source] Expression of Nox4 in osteoclastsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2004Su Yang Abstract A new superoxide-generating enzyme, NADPH oxidase 4 (Nox4), contributes to osteoclastic superoxide production. In this study, we demonstrated that Nox4 is expressed at a higher level in osteoclasts than that in precursor cells. This result suggested that Nox4 is upregulated during the differentiation and development of osteoclasts. Cotransfection of Nox4/P22 DNA resulted in enhanced superoxide production in osteoclasts, indicating that P22 may be a necessary factor for the Nox4 activity. In addition, expression of both cathepsin K and TRAP is increased significantly in osteoclasts cotransfected with Nox4/P22. Further study revealed that JNK was activated and that NF-,B was inhibited in Nox4/P22 cotransfected osteoclasts. These findings suggest that superoxide and/or superoxide derived molecules may modulate the signal transduction pathways necessary for osteoclasts to function. © 2004 Wiley-Liss, Inc. [source] Regulation of osteoclastogenesis and RANK expression by TGF-,1JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2001Tao Yan Abstract Transforming growth factor-, (TGF-,) has been shown to both inhibit and to stimulate bone resorption and osteoclastogenesis. This may be due, in part, to differential effects on bone marrow stromal cells that support osteoclastogenesis vs. direct effects on osteoclastic precursor cells. In the present study, we used the murine monocytic cell line, RAW 264.7, to define direct effects of TGF-, on pre-osteoclastic cells. In the presence of macrophage-colony stimulating factor (M-CSF) (20 ng/ml) and receptor activator of NF-,B ligand (RANK-L) (50 ng/ml), TGF-,1 (0.01,5 ng/ml) dose-dependently stimulated (by up to 120-fold) osteoclast formation (assessed by the presence of tartrate-resistant acid phosphatase (TRAP) positive multinucleated cells and expression of calcitonin and vitronectin receptors). In addition, TGF-,1 also increased steady state RANK mRNA levels in a time- (by up to 3.5-fold at 48 h) and dose-dependent manner (by up to 2.2-fold at 10 ng/ml). TGF-,1 induction of RANK mRNA levels was present both in undifferentiated RAW cells as well as in cells that had been induced to differentiate into osteoclasts by a 7-day treatment with M-CSF and RANK-L. Using a fluorescence-labeled RANK-L probe, we also demonstrated by flow cytometry that TGF-,1 resulted in a significant increase in the percentage of RANK+ RAW cells (P,<,0.05), as well as an increase in the fluorescence intensity per cell (P,<,0.05), the latter consistent with an increase in RANK protein expression per cell. These data thus indicate that TGF-, directly stimulates osteoclastic differentiation, and this is accompanied by increased RANK mRNA and protein expression. J. Cell. Biochem. 83: 320,325, 2001. © 2001 Wiley-Liss, Inc. [source] Oxidized low density lipoprotein decreases Rankl-induced differentiation of osteoclasts by inhibition of Rankl signaling,JOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2009Cécile Mazičre The role of OxLDL in the generation and progression of atherosclerosis is well admitted. In addition, it is well known that atherosclerosis is often accompanied by perturbations in bone remodeling, resulting in osteoporosis. In the current studies, the effect of Cu2+ -oxidized LDL (OxLDL) on RANKL-induced RAW264.7 mouse monocytes-macrophages differentiation to osteoclasts and on RANKL signaling pathway was investigated. OxLDL, within the range of 10,50,µg protein/ml, prevented RANKL-induced generation of multinucleated osteoclast-like cells and RANKL-induced tartrate resistant acid phosphatase (TRAP) activity. OxLDL also prevented the RANKL-induced phosphorylation of ERK, p38 and JNK kinases, together with the RANKL-induced DNA binding activities of NFkappaB and NFAT transcription factors. Concomitantly, OxLDL enhanced RANKL-induced generation of reactive oxygen species in a dose-dependent manner. The antioxidant glutathione (GSH) prevented whereas the prooxidant compound buthionine-sulfoximine (BSO) enhanced the effect of OxLDL on RANKL-induced oxidative stress and RANKL-induced differentiation. Finally, OxLDL also prevented RANKL-induced TRAP activity and RANKL-induced bone resorbing activity of human peripheral blood mononuclear cells. These results demonstrate that OxLDL, by generation of an intracellular oxidative stress, prevents the differentiation of osteoclasts by inhibition of RANKL signaling pathway. This might be related to the fact that atherosclerosis is accompanied by perturbations in bone and vascular remodeling, leading to osteoporosis and vascular calcification. J. Cell. Physiol. 221: 572,578, 2009. © 2009 Wiley-Liss, Inc. [source] Active caspase-3 is required for osteoclast differentiationJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2006K.H. Szymczyk Based on our earlier observation that caspase-3 is present in osteoclasts that are not undergoing apoptosis, we investigated the role of this protein in the differentiation of primary osteoclasts and RAW264.7 cells (Szymczyk KH, et al., 2005, Caspase-3 activity is necessary for RANKL-induced osteoclast differentiation. The Proceedings of the 8th ICCBMT). We noted that osteoclast numbers are decreased in long bones of procaspase-3 knockout mice and that receptor activator of NF-,B ligand (RANKL) does not promote differentiation of isolated preosteoclasts. In addition, after treatment with inhibitors of caspase-3 activity, neither the wild-type primary nor the RAW264.7 cells express TRAP or became multinucleated. We found that immediately following RANKL treatment, procaspase-3 is cleaved and the activated protein is localized to lipid regions of the plasma membrane and the cytosol. We developed RAW264.7 procaspase-3 knockdown clonal cell lines using RNAi technology. Again, treatment with RANKL fails to induce TRAP activity or multinucleation. Finally, we evaluated NF-,B in procaspase-3 silenced cells. We found that RANKL treatment prevented activation and nuclear translocation of NF-,B. Together these findings provide direct support for the hypothesis that caspase-3 activity is required for osteoclast differentiation. J. Cell. Physiol. 209: 836,844, 2006. © 2006 Wiley-Liss, Inc. [source] CXCL12 chemokine up-regulates bone resorption and MMP-9 release by human osteoclasts: CXCL12 levels are increased in synovial and bone tissue of rheumatoid arthritis patientsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 2 2004Francesco Grassi Chemokines are involved in a number of inflammatory pathologies and some of them show a pivotal role in the modulation of osteoclast development. Therefore, we evaluated the role of CXCL12 chemokine on osteoclast differentiation and function and we analyzed its expression on synovial and bone tissue biopsies from rheumatoid arthritis (RA) patients. Osteoclasts were obtained by 7 days in vitro differentiation with RANKL and M-CSF of CD11b positive cells in the presence or absence of CXCL12. The total number of osteoclast was analyzed by Tartrate-resistant acid phosphatase (TRAP)-staining and bone-resorbing activity was assessed by pit assay. MMP-9 and TIMP-1 release was evaluated by ELISA assay. CXCL12 expression on biopsies from RA patients was analyzed by immunohistochemistry. Osteoclasts obtained in the presence of CXCL12 at 10 nM concentration displayed a highly significant increase in bone-resorbing activity as measured by pit resorption assay, while the total number of mature osteoclasts was not affected. The increased resorption is associated with overexpression of MMP-9. Immunostaining for CXCL12 on synovial and bone tissue biopsies from both rheumatoid arthritis (RA) and osteoarthritis (OA) samples revealed a strong increase in the expression levels under inflammatory conditions. CXCL12 chemokine showed a clear activating role on mature osteoclast by inducing bone-resorbing activity and specific MMP-9 enzymatic release. Moreover, since bone and synovial biopsies from RA patients showed an elevated CXCL12 expression, these findings may provide useful tools for achieving a full elucidation of the complex network that regulates osteoclast function in course of inflammatory diseases. J. Cell. Physiol. 199: 244,251, 2004© 2003 Wiley-Liss, Inc. [source] The influence of reactivation of the telomerase in tumour tissue on the prognosis of squamous cell carcinomas in the head and neckJOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 9 2004S. Koscielny Background:, The reactivation of the telomerase seems to be an important step in the carcinogenesis of most human cancer types. Cell clones, which express this enzyme, get the ability of indefinite proliferation, means become immortal. Methods:, In this study, 80 patients with squamous cell carcinomas (SSC) in oral cavity, oropharynx, hypopharynx and larynx were recorded prospectively concerning a possible correlation of telomerase activity and clinical and prognostic factors. Telomerase activity was analysed by a modified telomeric repeat amplification protocol (TRAP) assay. Results:, In 75% of the tumour tissues the telomerase was demonstrated independently of the localization of the tumour. The known clinical prognostic factors did not show any correlation to the expression rate of the telomerase activity in the tumour tissues. Also, reactivated telomerase did not affect the tumour-dependent survival. Only the number of lymph node metastases was in tendency higher in patients with telomerase-positive tumours. The number and timeframe of local and regional recurrences was not influenced by the telomerase status. Conclusions:, Although telomerase seems to be an important part of the carcinogenesis of SCC our data show that the reactivation of telomerase in tumour tissue did not have any prognostic significance for these tumours. The tendency that tumours with active telomerase developed lymph node metastases in a higher number should be evaluated by further enlarged studies for its clinical relevance. [source] Expression profiling reveals alternative macrophage activation and impaired osteogenesis in periprosthetic osteolysisJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 1 2008Panagiotis Koulouvaris Abstract Interactions between periprosthetic cells and prosthetic wear debris have been recognized as an important event in the development of osteolysis and aseptic loosening. Although the ability of wear debris to activate pro-inflammatory macrophage signaling has been documented, the full repertoire of macrophage responses to wear particles has not been established. Here, we examined the involvement of alternative macrophage activation and defective osteogenic signaling in osteolysis. Using real-time RT-PCR analysis of periprosthetic soft tissue from osteolysis patients, we detected elevated levels of expression of alternative macrophage activation markers (CHIT1, CCL18), chemokines (IL8, MIP1 ,) and markers of osteoclast precursor cell differentiation and multinucleation (Cathepsin K, TRAP, DC-STAMP) relative to osteoarthritis controls. The presence of cathepsin K positive multinuclear cells was confirmed by immunohistochemistry. Reduced expression levels of the osteogenic signaling components BMP4 and FGF18 were detected. Expression levels of TNF-,, IL-6, and RANKL were unchanged, while the anti-osteoclastogenic cytokine OPG was reduced in osteolysis patients, resulting in elevated RANKL:OPG ratios. In vitro studies confirmed the role of particulate debris in alternative macrophage activation and inhibition of osteogenic signaling. Taken together, these results suggest involvement in osteolysis of alternative macrophage activation, accompanied by elevated levels of various chemokines. Increased recruitment and maturation of osteoclast precursors is also observed, as is reduced osteogenesis. These findings provide new insights into the molecular pathogenesis of osteolysis, and identify new potential candidate markers for disease progression and therapeutic targeting. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:106,116, 2008 [source] Arthroplasty membrane-derived fibroblasts directly induce osteoclast formation and osteolysis in aseptic looseningJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2005A. Sabokbar Abstract Purpose: Both macrophages and fibroblasts are the main cell types found in periprosthetic tissues surrounding failed joint arthroplasties. These fibroblasts are known to express RANKL and to produce TNF,, factors which promote osteoclast formation and bone resorption. In this study we have analysed the role that arthroplasty membrane-derived fibroblasts (AFb) play in inducing the generation of bone resorbing osteoclasts. Methods: Fibroblasts were isolated from periprosthetic tissues and co-cultured with human monocytes in an osteoclast differentiation assay in the presence or absence of M-CSF and inhibitors of RANKL (OPG) and/or TNF,. RANKL expression by AFbs was determined by RT-PCR and the extent of osteoclast differentiation by the expression of TRAP, VNR and evidence of lacunar resorption. Results: In the presence of M-CSF, large numbers of TRAP+ and VNR+ multinucleated cells capable of lacunar resorption, were noted in co-cultures of monocytes and RANKL-expressing AFbs. Cell-cell contact was required for osteoclast formation. The addition of OPG and anti-TNF, alone significantly reduced but did not abolish the extent of osteoclast formation, whereas the addition of both together abolished osteoclast formation and lacunar resorption. Conclusion: Our results indicate that fibroblasts in periprosthetic tissues are capable of inducing the differentiation of normal human peripheral blood mononuclear cells to mature osteoclasts by a mechanism that involves both RANKL and TNF,. Suppression of both RANKL and inflammatory cytokines is likely to be required to control periprosthetic osteolysis. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved. [source] (-)-Epigallocatechin gallate induces apoptosis, via caspase activation, in osteoclasts differentiated from RAW 264.7 cellsJOURNAL OF PERIODONTAL RESEARCH, Issue 3 2007J.-H. Yun Background and Objective:, Alveolar bone resorption is a characteristic feature of periodontal diseases and involves removal of both the mineral and the organic constituents of the bone matrix, a process mainly carried out by multinucleated osteoclast cells. (-)-Epigallocatechin gallate, the main constituent of green tea polyphenols, has been reported to induce the apoptotic cell death of osteoclasts and to modulate caspase activation in various tumor cells. In the present study, we investigated the inhibitory effect of (-)-epigallocatechin gallate on osteoclast survival and examined if (-)-epigallocatechin gallate mediates osteoclast apoptosis via caspase activation. Material and Methods:, The effect of (-)-epigallocatechin gallate on osteoclast survival was examined by tartrate-resistant acid phosphatase (TRAP) staining in osteoclasts differentiated from RAW 264.7 cells. In addition, we evaluated the apoptosis of osteoclasts by (-)-epigallocatechin gallate using a DNA-fragmentation assay. Involvement of caspase in (-)-epigallocatechin gallate-mediated osteoclast apoptosis was evaluated by treatment with a general caspase inhibitor, Z-VAD-FMK. Moreover, the effect of (-)-epigallocatechin gallate on the activation of caspase-3 was assessed by a colorimetric activity assay and western blotting. Results:, (-)-Epigallocatechin gallate significantly inhibited, in a dose-dependent manner, the survival of osteoclasts differentiated from RAW 264.7 cells and induced the apoptosis of osteoclasts. Treatment with (-)-epigallocatechin gallate resulted in DNA fragmentation and induced the activation of caspase-3 in RAW 264.7 cell-derived osteoclasts. Additional treatment with Z-VAD-FMK suppressed these effects of (-)-epigallocatechin gallate. Conclusion:, From these findings, we could suggest that (-)-epigallocatechin gallate might prevent alveolar bone resorption by inhibiting osteoclast survival through the caspase-mediated apoptosis. [source] Inhibitory effects of green tea polyphenol (,)-epigallocatechin gallate on the expression of matrix metalloproteinase-9 and on the formation of osteoclastsJOURNAL OF PERIODONTAL RESEARCH, Issue 5 2004Jeong-Ho Yun Background:, Alveolar bone resorption is a characteristic feature of periodontal diseases and involves the removal of both the mineral and organic constituents of the bone matrix, which is caused by either multinucleated osteoclast cells or matrix metalloproteinases (MMPs). The gram-negative bacterium, Porphyromonas gingivalis has been reported to stimulate the activity and expression of several groups of MMPs, whereas (,)-epigallocatechin gallate (EGCG), the main constituent of green tea polyphenols, has been reported to have inhibitory effects on the activity and expression of MMPs. Objectives:, In the present study, we investigated the effects of the green tea polyphenol, EGCG, on the gene expression of osteoblast-derived MMP-2, -9 and -13, stimulated by P. gingivalis, and on the formation of osteoclasts. Methods:, The effect of EGCG on the gene expression of MMPs was examined by treating mouse calvarial primary osteoblastic cells with EGCG (20 µm) in the presence of sonicated P. gingivalis extracts. The transcription levels of MMP-2, -9 and -13 were assessed by reverse transcription-polymerase chain reaction (RT-PCR). The effect of EGCG on osteoclast formation was confirmed by tartrate-resistant acid phosphatase (TRAP) staining in a co-culture system of mouse bone marrow cells and calvarial primary osteoblastic cells. Results:, Treatment with the sonicated P. gingivalis extracts stimulated the expression of MMP-9 mRNA and this effect was significantly reduced by EGCG, whereas the transcription levels of MMP-2 and MMP-13 were not affected by either the sonicated P. gingivalis extracts or EGCG. In addition, EGCG significantly inhibited osteoclast formation in the co-culture system at a concentration of 20 µm. Conclusions:, These findings suggest that EGCG may prevent the alveolar bone resorption that occurs in periodontal diseases by inhibiting the expression of MMP-9 in osteoblasts and the formation of osteoclasts. [source] Dental root resorption and repair: histology and histometry during physiological drift of rat molarsJOURNAL OF PERIODONTAL RESEARCH, Issue 5 2003Ryusei Kimura Objective:, The process of dental root resorption and subsequent cementum regeneration has not been sufficiently elucidated. This study aimed to examine the process of the root resorption and cementum regeneration during physiological tooth drift using a rat model, and to evaluate this experimental model. Methods:, Distal roots in mandibular first molars and the surrounding periodontal tissues were investigated with light and electron microscopy. The light microscopic approach included histochemical and histometric analyses utilizing the tartrate-resistant acid phosphatase (TRAP) reaction. Results:, Root resorption was observed in the distal side of the roots and was most active in 5- to 6-week-old rats, and gradually decreased hereafter. An increase in the number of TRAP-positive mononuclear cells, which seemed to be odontoclast precursor cells, preceded the increase in the number of odontoclasts. Root resorption was transient, and was followed by the new formation of acellular extrinsic fiber cementum accompanied with only a slight inflammation, and therefore classified as external surface resorption. Preparation for new cementum started adjacent to the resorption areas when root resorption was most active. Conclusions:, The root resorption during drift in rats is transient and followed by acellular extrinsic fiber cementum regeneration. Cellular kinetics suggested that odontoclast precursor cells are supplied as mononuclear cells from vascular spaces. [source] THE EVOLUTION OF A MODEL TRAP IN THE CENTRAL APENNINES, ITALY: FRACTURE PATTERNS, FAULT REACTIVATION AND DEVELOPMENT OF CATACLASTIC ROCKS IN CARBONATES AT THE NARNI ANTICLINEJOURNAL OF PETROLEUM GEOLOGY, Issue 2 2001F. Storti Recent hydrocarbon discoveries in the Southern Apennines of Italy have focussed attention on the importance of studying fracturing and cataclasis in carbonate rocks because of their fundamental impact on reservoir permeability and connectivity. The Narni Anticline in the central Apennines consists of a stack of easterly-verging carbonate thrust sheets compartmentalized by extensional and strike-slip fault zones. The structure provides afield analogue for studying the evolution of superimposed fold- and fault-related fractures in carbonate reservoir rocks. The fracture pattern at the Narni Anticline developed as a result of three mechanisms: (a) layer-parallel shortening predating folding and faulting; (b) thrust-related folding and further thrust breakthrough; and (c) extensional and strike-slip faulting. Along-strike (longitudinal) fractures developed during progressive rollover fault-propagation folding, and their intensity depends on the precise structural position within the fold: fracture intensity is high in the forelimb and low in the crest. The 3-D architecture of the mechanical anisotropy associated with thrusting, folding, and related fracturing constrained the location and geometry of subsequent extensional and strike-slip faulting. The superimposition in damage zones of a fault-related cleavage on the pre-existing fracture pattern, which is associated with layer-parallel shortening and thrust-related folding, resulted in rock fragmentation and comminution, and the development of cataclastic bands. The evolution of fracturing in the Narni Anticline, its role in constraining thrust breakthrough trajectories and the location of extensional and strike-slip faults, and the final development of low-permeability cataclastic bands, will be relevant to studies of known oilfields in the Southern Apennines, as well as for future exploration. [source] Complement activation triggered by chondroitin sulfate released by thrombin receptor-activated plateletsJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 8 2008O. A. HAMAD Summary.,Background:,Chondroitin sulfate (CS) is a glycosaminoglycan released by activated platelets. Objective:,Here we test the hypothesis that CS released by activated platelets can trigger complement activation in the fluid phase. Methods and results:,Thrombin receptor-activating peptide (TRAP)-6 was used to activate platelets in platelet-rich plasma and blood, anticoagulated with the thrombin inhibitor lepirudin. TRAP activation induced fluid-phase complement activation, as reflected by the generation of C3a and sC5b-9, which could be attenuated by the C3 inhibitor compstatin. Chondroitinase ABC treatment of supernatants from activated platelets totally inhibited the activation, indicating that platelet-derived CS had initiated the complement activation. Furthermore, addition of purified CS to plasma strongly triggered complement activation. C1q was identified as the recognition molecule, as it bound directly to CS, and CS-triggered complement activation could be restored in C1q-depleted serum by adding purified C1q. TRAP activation of whole blood increased the expression of CD11b on leukocytes and generation of leukocyte,platelet complexes. It was demonstrated that these leukocyte functions were dependent on C3 activation and signaling via C5a, as this expression could be inhibited by compstatin and by a C5aR antagonist. Conclusions:,We conclude that platelets trigger complement activation in the fluid phase by releasing CS, which leads to inflammatory signals mediated by C5a. [source] A differential role of the platelet ADP receptors P2Y1 and P2Y12 in Rac activationJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 10 2005C. SOULET Summary., The dynamics of the actin cytoskeleton, largely controlled by the Rho family of small GTPases (Rho, Rac and Cdc42), is critical for the regulation of platelet responses such as shape change, adhesion, spreading and aggregation. Here, we investigated the role of adenosine diphosphate (ADP), a major co-activator of platelets, on the activation of Rac. ADP rapidly activated Rac in a dose-dependent manner and independently of GPIIb/IIIa and phosphoinositide 3-kinase. ADP alone, used as a primary agonist, activated Rac and its effector PAK via its P2Y1 receptor, through a Gq -dependent pathway and independently of P2Y12. The P2Y12 receptor appeared unable to activate the GTPase per se as also observed for the adenosine triphosphate receptor P2X1. Conversely, secreted ADP strongly potentiated Rac activation induced by Fc,RIIa clustering or TRAP via its P2Y12 receptor, the target of antithrombotic thienopyridines. Stimulation of the ,2A -adrenergic receptor/Gz pathway by epinephrine was able to replace the P2Y12/Gi -mediated pathway to amplify Rac activation by Fc,RIIa or by the thrombin receptor PAR-1. This co-activation appeared necessary to reach a full stimulation of Rac as well as PAK activation and actin polymerization and was blocked by a G-protein ,, subunits scavenger peptide. [source] Oxidative stress may enhance the malignant potential of human hepatocellular carcinoma by telomerase activationLIVER INTERNATIONAL, Issue 6 2009Taichiro Nishikawa Abstract Background/Aims: Continuous oxidative stress (OS) plays an important role in the progression of chronic liver diseases and hepatocarcinogenesis through telomere shortening in hepatocytes. However, it has not been established how the OS influences the progression of human hepatocellular carcinomas (HCCs). We examined the correlations of OS with telomere length of cancer cells, telomerase activity and other clinicopathological factors in 68 HCCs. Methods: The level of 8-hydroxy-2,-deoxyguanosine (8-OHdG) as a marker of OS was examined immunohistochemically and OS was scored in four grades (0,3). The telomere length of cancer cells was measured by quantitative fluorescence in situ hybridization. Telomerase activity was measured by (i) immunodetection of human telomerase reverse transcriptase (hTERT) and (ii) telomere repeat amplification protocol (TRAP) assay. Telomerase related proteins, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and Akt, and other clinicopathological factors were also evaluated. Results: As the OS grade increased, the average telomere length became significantly shorter in HCCs, especially in the hTERT-negative group. In the state of high-grade OS, hTERT-positive HCC cells showed more proliferative and less apoptotic features compared with hTERT-negative HCC cells. Telomerase activity, as measured by the TRAP assay, was strongly correlated with OS grade in HCCs. Furthermore, a high OS grade was correlated with the downexpression of PTEN and the activation of Akt. Conclusions: Oxidative stress enhanced the malignant potential of HCCs through the activation of telomerase, which raises the possibility of using OS as a marker for assessing the clinical state of HCCs. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||