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Primary Cultures (primary + culture)
Terms modified by Primary Cultures Selected AbstractsAttenuation of Bleomycin-Induced Lung Fibrosis by Oxymatrine Is Associated with Regulation of Fibroblast Proliferation and Collagen Production in Primary CultureBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 3 2008Xiaohong Chen Oxymatrine is an alkaloid extracted from the Chinese herb Sophora japonica (Sophora flavescens Ait.) with capacities of anti-inflammation, inhibition of immune reaction, antivirus, protection against acute lung injury and antihepatic fibrosis. In this study, the effect of oxymatrine on pulmonary fibrosis was investigated using a bleomycin-induced pulmonary fibrosis mouse model. The results showed that bleomycin challenge provoked severe pulmonary fibrosis with marked increase in hydroxyproline content of lung tissue and lung fibrosis fraction, which was prevented by oxymatrine in a dose-dependent manner. In addition, bleomycin injection resulted in a marked increase of myeloperoxidase activity and malondialdehyde level that was attenuated by oxymatrine. Administration of oxymatrine inhibited the proliferation of murine lung fibroblasts, arrested the cells at G0/G1 phase and reduced the expression of cell cycle regulatory protein, cyclin D1 in vitro. Furthermore, the steady-state production of collagen and the expression of ,1(I) pro-collagen and ,2(I) pro-collagen mRNA in fibroblasts were inhibited by oxymatrine in a dose-dependent manner. These results suggested that oxymatrine may attenuate pulmonary fibrosis induced by bleomycin in mice, partly through inhibition of inflammatory response and lipid peroxidation in lung induced by bleomycin and reduction of fibroblast proliferation and collagen synthesis. [source] Retroviral labeling of Schwann cells: In vitro characterization and in vivo transplantation to improve peripheral nerve regenerationGLIA, Issue 1 2001Afshin Mosahebi Abstract Transplantation of Schwann cells (SCs) is a promising treatment modality to improve neuronal regeneration. Identification of the transplanted cells is an important step when studying the development of this method. Genetic labeling is the most stable and reliable method of cell identification, but it is still unclear whether it has deleterious effect on SC characteristics. Our aim was to achieve a stable population of SCs transduced with the lacZ gene at a high frequency using a retroviral vector in vitro, and to follow the labeled SC in vitro to assess their viability and phenotypic marker expression. Furthermore, we transplanted lacZ -labeled SCs in a conduit to repair peripheral nerve to investigate their effect on nerve regeneration in vivo. Rat and human SCs were cultured and transduced with an MFG lacZ nls marker gene, achieving a transduction rate of 80% and 70%, respectively. Rat SCs were kept in culture for 27 weeks and examined every 4 weeks for expression of lacZ, viability, and phenotypic marker expression of GFAP, p75, MHC I and II. Throughout this period, transduced rat SCs remained viable and continued to proliferate. The proportion of cells expressing lacZ dropped only by 10% and the expression of phenotypic markers remained stable. Transduced human SCs were followed up for 4 weeks in culture. They proliferated and continued to express the lacZ gene and phenotypic marker expression of GFAP and p75 was preserved. Primary culture of transduced rat SCs were transplanted, syngeneically, in a conduit to bridge a 10 mm gap in sciatic nerve and the grafts were examined after 3 weeks for the presence and participation of labeled SCs and for axonal regeneration distance. Transplanted transduced rat SCs were clearly identified, taking part in the regeneration process and enhancing the axonal regeneration rate by 100% (at the optimal concentration) compared to conduits without SCs. Thus, retroviral introduction of lacZ gene has no deleterious effect on SCs in vitro and these SCs take part and enhance nerve regeneration in vivo. GLIA 34:8,17, 2001. © 2001 Wiley-Liss, Inc. [source] 3241: Effect of glutaredoxin 2 gene knockout on lens epithelial cells against oxidative stressACTA OPHTHALMOLOGICA, Issue 2010M LOU Purpose The mitochondrial glutaredoxin 2 (Grx2) is known to possess both dethiolase and peroxidase activities, and has shown an ability to protect cells from oxidative stress-induced apoptosis in the human lens epithelial cells. In this study, we further studied the function of Grx2 by using Grx2 knockout mouse lens epithelial (MLE) cells as a model. Methods Primary culture of MLE cells was established from the lenses of wild-type (WT) and Grx2-knockout (Grx2 KO) mice. Cells were probed for ,A-crystallin and Grx2 by Western blot analysis while cell viability was examined by WST-8 assay. Glutathione (GSH) level, Grx2 and Complex I activities, and lactate dehydrogenase (LDH) release were determined by spectrophotometric assays. Reactive oxygen species was detected using DCF-DA fluorescein with a cell sorter. Apoptosis was quantified by flow cytometry. Results Both primary cell cultures were confirmed to be lens epithelial cells by the presence of ,A-crystallin. Western blotting showed normal expression of Grx2 in WT cells but absent in Grx2 KO cells. Both cell types showed similar morphology and growth rate with same level of GSH pool and complex 1 activity in the mitochondrial fraction. However, KO cells were more sensitive to oxidative stress (100 ,M H2O2 for 6 h) and exhibited lower cell viability and more LDH leakage in comparison with the WT cells. In addition, knockdown of Grx2 weakened the cell's ability to detoxify H2O2 and enhanced the H2O2-induced inactivation of complex I in the electron transport chain. Conclusion Grx2 can protect MLE cells from H2O2-induced cell injury, and the mechanism of this protection is likely associated with its ability to detoxify H2O2 and its preservation of complex I activity in the mitochondria. [source] Effect of silybin and its glycosides on the expression of cytochromes P450 1A2 and 3A4 in primary cultures of human hepatocytesJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 3 2005Pavel Kosina Abstract Four ,-glycosides of flavonoligan silybin, i.e. silybin ,-galactoside, silybin ,-glucoside, silybin ,-maltoside, silybin ,-lactoside were synthesized in order to improve silybin water solubility and bioavailability (K,en et al., J Chem Soc, Perkin Trans 1, 2467,2474, 1997). The presented paper deals with the effect of silybin and its synthetic ,-glycosides on the expression of two major cytochrome P450 isoforms, CYP1A2 and CYP3A4. Primary cultures of human hepatocytes were the model of choice. mRNAs were analyzed using Northern blot and P-radiolabelled probes. CYP protein content was determined by immunoblotting using specific antibodies. Silybin and its ,-glycosides do not induce expression of CYP1A2 and CYP3A4. Tested compounds did not affect inducible expression of CYP1A2 and CYP3A4 by dioxin and rifampicin, respectively, as evaluated at the level of mRNAs and proteins. Silybin and its ,-glycosides do not interfere with the expression of CYP1A2 and CYP3A4, are not likely to produce drug,drug interactions in terms of the inducibility of two important cytochromes P450. © 2005 Wiley Periodicals, Inc. J Biochem Mol Toxicol 19:149,153, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20066 [source] Are primary cultures realistic models of prostate cancer?JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2004Donna M. Peehl Abstract Primary cultures fill a unique niche among the repertoire of in vitro model systems available to investigate the biology of the normal and malignant human prostate. This review summarizes some of the properties of primary cultures, with special emphasis on two questions: are primary cultures from adenocarcinomas really comprised of cancer rather than normal cells, and do primary cultures faithfully retain characteristics of cells of origin? © 2003 Wiley-Liss, Inc. [source] Isoflurane enhances spontaneous Ca2+ oscillations in developing rat hippocampal neurons in vitroACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 6 2009Q. XIANG Background: During the nervous system development, spontaneous synchronized Ca2+ oscillations are thought to possess integrative properties because their amplitude and frequency can influence the patterning of neuronal connection, neuronal differentiation, axon outgrowth, and long-distance wiring. Accumulating studies have confirmed that some drugs such as volatile anesthetic isoflurane produced histopathologic changes in the central nervous system in juvenile animal models. Because the hippocampus plays an important role in learning and memory, the present work was designed to characterize the Ca2+ oscillations regulated by volatile anesthetic isoflurane in primary cultures of developing hippocampal neurons (5-day-cultured). Methods: Primary cultures of rat hippocampal neurons (5-day-cultured) were loaded with the Ca2+ indicator Fluo-4AM (4 ,M) and were studied with a confocal laser microscope. Results: Approximately 22% of 5-day-cultured hippocampal neurons exhibited typical Ca2+ oscillations. These oscillations were dose-dependently enhanced by isoflurane (EC50 0.5 MAC, minimum alveolar concentration) and this effect could be reverted by bicuculline (50 ,M), a specific ,-aminobutyric acid (GABAA) receptor antagonist. Conclusion: Unlike its depressant effect on the Ca2+ oscillations in adult neurons in previous researches, isoflurane dose-dependently enhanced calcium oscillations in developing hippocampal neurons by activating GABAA receptors, a major excitatory receptor in synergy with N -methyl- d -aspartate receptors at the early stages of development. It may be involved in the mechanism of an isoflurane-induced neurotoxic effect in the developing rodent brain. [source] Enzymatic Degradation Protects Neurons from Glutamate ExcitotoxicityJOURNAL OF NEUROCHEMISTRY, Issue 3 2000Christopher C. Matthews Abstract: Several enzymes with the capacity to degrade glutamate have been suggested as possible neuroprotectants. We initially evaluated the kinetic properties of glutamate pyruvate transaminase (GPT; also known as alanine aminotransferase), glutamine synthetase, and glutamate dehydrogenase under physiologic conditions to degrade neurotoxic concentrations of glutamate. Although all three enzymes initially degraded glutamate rapidly, only GPT was able to reduce toxic (500 ,M) levels of glutamate into the physiologic (<20 ,M) range. Primary cultures of fetal murine cortical neurons were subjected to paradigms of either exogenous or endogenous glutamate toxicity to evaluate the neuroprotective value of GPT. Neuronal survival after exposure to added glutamate ranging from 100 to 500 ,M was improved significantly in the presence of GPT (,1 U/ml). Cultures were also exposed to the glutamate transporter inhibitor L- trans -pyrrolidine-2,4-dicarboxylate (PDC), which produces neuronal injury by elevating extracellular glutamate. GPT significantly reduced the toxicity of PDC. This reduction was associated with a reduction in the PDC-dependent rise in the medium concentration of glutamate. These results suggest that enzymatic degradation of glutamate by GPT can be an alternative to glutamate receptor blockade as a strategy to protect neurons from excitotoxic injury. [source] Prostaglandin E2 secretion from gingival fibroblasts treated with interleukin-1,: effects of lipid extracts from Porphyromonas gingivalis or calculusJOURNAL OF PERIODONTAL RESEARCH, Issue 3 2001Frank C. Nichols Complex lipids of Porphyromonas gingivalis have been identified in lipid extracts from calculus-contaminated root surfaces and in diseased gingival tissues. However, little is known about the biological effects of these complex lipids on host cells. The purpose of this study was to evaluate the effects of P. gingivalis or calculus lipids on prostaglandin secretion from gingival fibroblasts. Lipids were extracted from paired subgingival plaque and teeth samples, and calculus-contaminated root surfaces before and after scaling and root planing, in order to determine the relevant levels of lipid extracts for the treatment of gingival fibroblasts in culture. Primary cultures of gingival fibroblasts were exposed to lipid extracts from either P. gingivalis or calculus/teeth for a period of 7 days. Control and lipid-treated cultures were exposed to human recombinant interleukin-1, for 48 h and prostaglandin secretion from interleukin-1,-treated fibroblasts was compared with control and lipid-treated fibroblasts without interleukin-1, treatment. These experiments demonstrated that P. gingivalis lipids or calculus-tooth lipids potentiate interleukin-1,-mediated prostaglandin secretory responses from gingival fibroblasts. Additionally, P. gingivalis or calculus-tooth lipid extracts were readily taken up by gingival fibroblasts as measured by bacterial fatty acid recovery in lipid extracts of cultured fibroblasts. These results indicate that bacterial lipid penetration into gingival tissues in combination with a chronic inflammatory response may substantially potentiate prostaglandin secretion from gingival fibroblasts, thereby promoting tissue destructive processes associated with adult periodontitis. [source] Effects of Ethanol and Transforming Growth Factor , (TGF,) on Neuronal Proliferation and nCAM ExpressionALCOHOLISM, Issue 8 2002Michael W. Miller Background Developmental events targeted by ethanol are cell proliferation, neuronal migration, and neurite outgrowth; the latter processes being mediated by neural cell adhesion molecule (nCAM). TGF,1 affects all three of these events. Therefore, the effects of ethanol on transforming growth factor (TGF) ,1 mediated activities in neocortical neurons in vitro were examined. Methods Primary cultures of cortical neurons were obtained from 16-day-old fetuses and were treated with TGF,1 (0 or 10 ng/ml) and ethanol (0 or 400 mg/dl) for 48 hr. The effects of these substances on cell numbers, [3H]thymidine incorporation, and the expression of nCAM were determined. Results Both cell growth (the change in cell numbers over time) and cell proliferation were inhibited by TGF,1 and ethanol. The action of these two anti-mitogenic factors was additive. In contrast, TGF,1 also promoted the expression of three isoforms of nCAM. Likewise, ethanol also up-regulated nCAM expression. On the other hand, ethanol blocked TGF,1-mediated nCAM expression, particularly of the 120 and 180 kDa isoforms. Conclusions TGF, ligands inhibit neuronal proliferation and stimulate the expression of cell adhesion proteins that promote the movement of postmitotic neurons and process outgrowth. Ethanol alters these phenomena as well. Thus, in neurons, as in astrocytes, TGF,1 and ethanol may interact. [source] Atorvastatin induces apoptosis by a caspase-9-dependent pathway: an in vitro study on activated rat hepatic stellate cellsLIVER INTERNATIONAL, Issue 4 2008Isabella Aprigliano Abstract Background: Statins are shown to have cholesterol-independent properties such as anti-inflammation and immunomodulation. Activated hepatic stellate cells (HSCs) acquire the capacity to synthesize matrix proteins in damaged liver. We tested the hypothesis that atorvastatin may be capable of inducing apoptosis in HSCs. Methods: Primary cultures of rat HSCs were exposed to atorvastatin, mevalonic acid and U0126. Quantification of living, apoptotic and necrotic HSCs was performed by flow cytometry and laser-scan microscopy. Cell-cycle analysis was performed by flow cytometry. Pro- and anti-apoptotic factors were investigated by Western blot and electrophoresis mobility shift assay. Protease activity of caspases was calculated using a colorimetric kit. Results: Atorvastatin leads to a G2-arrest and induces apoptosis in activated HSCs. Atorvastatin-mediated apoptosis could be blocked by co-administration of mevalonic acid and U0126. No effects of atorvastatin on gene expression of CD95, CD95L, NF-,B, p53 and p21WAF1 could be observed. Atorvastatin-induced apoptosis in activated HSCs is related to an increased protease activity of caspase-9 and -3. Gene expression of the major proteins of the bcl-system shows that truncated Bid is involved in apoptosis mediated by atorvastatin. By blocking the extracellular signal-regulated protein kinase (ERK1/2) activation by adding U0126, we could prevent the apoptosis induced by atorvastatin. By Western blot we could not detect any change in the activation of c-jun N-terminal kinase (JNK). Conclusions: Atorvastatin induces apoptosis in activated HSCs acting through an ERK-dependent cleavage of Bid and a highly increased protease activity of caspase-9 and -3. JNK is not involved in atorvastatin-mediated apoptosis in HSCs. [source] Growth and Differentiation of Osteoblast-Like Cells from Calvaria of Connexin43 Deficient MiceMATERIALWISSENSCHAFT UND WERKSTOFFTECHNIK, Issue 12 2004M. Wiemann Osteoblasten-artige Zellen; Connexin43-defiziente Mäuse; gap junctions; Differenzierung Abstract Extensive cell-cell-coupling via gap junctions has been suspected to play an essential role for osteoblast development. Here, osteoblast-like cells (OBL) from connexin(Cx)43 knock out mice were used to explore the role of Cx43 for osteoblast differentiation. Primary cultures of OBL were derived from calvaria of homozygous (Cx43-/-) and heterozygous (Cx43+/,) knock out mice and also from wild type controls (Cx43+/+). In Cx43-/- OBL Lucifer Yellow dye coupling was largely abolished demonstrating that small molecules could no longer be transferred among neighboring cells. Cx43-/- OBL grew out very slowly from calvarial fragments. Nevertheless their cell density around explants was increased 3-fold vs. controls after 3 weeks. Histochemistry showed that in many Cx43-/- OBL there was an increased alkaline phosphatase activity within the cytoplasm and close to the cell membrane. Mineralization was diminished in Cx43-/- cultures. In heterozygous Cx43+/, OBL all aforementioned effects were less pronounced, pointing to a gene-dosage effect. Data suggest that the loss of Cx43 indirectly impairs the osteoblastic phenotype, e.g. by disturbing cellular functions such as motility and/or secretion. If this holds true, all parameters in the interphase of enosseous implants which lower gap junction expression will also affect bone regeneration. Wachstum und Differenzierung von Osteoblasten-artigen Zellen aus Kalvarien Connexin43-defizienter Mäuse Es wurde oft vermutet, dass die ausgeprägte Zell-Zell-Kopplung von Osteoblasten durch gap junctions eine besondere Rolle für die Differenzierung der gekoppelten Zellen spielt. In dieser Arbeit wurden daher Osteoblasten-artige Zellen (OBL) aus Connexin43 (Cx43) knock out Mäusen benutzt, um die Bedeutung von Cx43-gap-junction-Kanälen für die Differenzierung von Osteoblasten zu untersuchen. Die dafür notwendigen OBL-Primärkulturen wurden aus Calvarienfragmenten von homozygoten (Cx43-/-) und heterozygoten (Cx43+/,) knock out Mäusen sowie aus Wildtyp-Mäusen gewonnen. In Cx43-/- OBL war die Lucifer Yellow-Farbstoffkopplung weitgehend aufgehoben. Dieser Befund zeigt, dass Moleküle ,600 D zwischen Cx43-/- Zellen kaum noch ausgetauscht werden können. Cx43-/- Zellen wuchsen vergleichsweise langsam aus ihren Calvarienfragmenten aus. Dennoch erreichten diese Kulturen nach 3 Wochen eine im Vergleich zur Kontrolle 3fach höhere Zelldichte. Histochemisch zeigte sich, dass in Cx43-/- Zellen die alkalische Phosphatase-Aktivität im Zytoplasma und besonders im Bereich der Zellmembran erhöht war. Die Mineralisierung war hingegen herabgesetzt. In heterozygoten Cx43+/, OBL waren alle genannten Effekte intermediär ausgeprägt, was auf einen Gen-Dosis-Effekt deutet. Insgesamt legen die Befunde nahe, dass der Verlust von Cx43 die Ausprägung des osteoblastären Phänotyps, z.,B. durch eine Behinderung der Zellbeweglichkeit und/oder der Sekretion beeinträchtigt. Daher dürften alle Parameter, die die Expression von Cx43 im Interphase eines enossalen Implantats stören, die Knochenregeneration behindern. [source] Cannabinoid receptor 1 signalling dampens activity and mitochondrial transport in networks of enteric neuronesNEUROGASTROENTEROLOGY & MOTILITY, Issue 9 2009W. Boesmans Abstract, Cannabinoid (CB) receptors are expressed in the enteric nervous system (ENS) and CB1 receptor activity slows down motility and delays gastric emptying. This receptor system has become an important target for GI-related drug development such as in obesity treatment. The aim of the study was to investigate how CB1 ligands and antagonists affect ongoing activity in enteric neurone networks, modulate synaptic vesicle cycling and influence mitochondrial transport in nerve processes. Primary cultures of guinea-pig myenteric neurones were loaded with different fluorescent markers: Fluo-4 to measure network activity, FM1-43 to image synaptic vesicles and Mitotracker green to label mitochondria. Synaptic vesicle cluster density was assessed by immunohistochemistry and expression of CB1 receptors was confirmed by RT-PCR. Spontaneous network activity, displayed by both excitatory and inhibitory neurones, was significantly increased by CB1 receptor antagonists (AM-251 and SR141716), abolished by CB1 activation (methanandamide, mAEA) and reduced by two different inhibitors (arachidonylamide serotonin, AA-5HT and URB597) of fatty acid amide hydrolase. Antagonists reduced the number of synaptic vesicles that were recycled during an electrical stimulus. CB1 agonists (mAEA and WIN55,212) reduced and antagonists enhanced the fraction of transported mitochondria in enteric nerve fibres. We found immunohistochemical evidence for an enhancement of synaptophysin-positive release sites with SR141716, while WIN55,212 caused a reduction. The opposite effects of agonists and antagonists suggest that enteric nerve signalling is under the permanent control of CB1 receptor activity. Using inhibitors of the endocannabinoid degrading enzyme, we were able to show there is endogenous production of a CB ligand in the ENS. [source] Apoptotic activity of doxazosin on prostate stroma in vitro is mediated through an autocrine expression of TGF-,1THE PROSTATE, Issue 3 2001Kenneth Y. Ilio Abstract Background Doxazosin, an alpha-adrenergic antagonist, has been shown to induce apoptosis in prostatic stromal cells. The mechanism of this apoptotic action by Doxazosin remains undefined. The present study was carried out to demonstrate that the effect of Doxazosin on apoptosis of prostate stromal cells is mediated through an autocrine action of TGF-,1. Methods Primary cultures of human prostate cells were treated with varying concentrations of Doxazosin (0, 0.1, 1, 10, and 100 ,M) for a period up to 3 days. At the end of the 3-day culture, cell numbers were counted. Apoptosis was assessed by a colorimetric terminal deoxyribonucleotide transferase labeling technique. TGF-,1 was determined by enzyme-linked immunosorbent assay (ELISA). Results Compared to control cultures, cell numbers were significantly decreased as much as 68.4% in cultures treated with 10 ,M of Doxazosin after 3 days incubation, while apoptosis increased by 64.7% in cultures treated with the same concentration of Doxazosin after 24 h. This decrease in cell number was reversed when antibody to TGF-,1 was added to these cultures. Addition of TGF-,1 (0, 1.0, and 10 ng/mL) to the cultures also decreased the cell numbers. Quantitation of TGF-,1 in lysates of cells by ELISA revealed that the cells treated with Doxazosin (10 ,M) produced as much as 62.5% more TGF-,1 than in that of untreated cells. Conclusions These results demonstrate that the apoptotic effect of Doxazosin on human prostatic stromal cells is mediated through an autocrine production of TGF-,1. Prostate 48:131,135, 2001. © 2001 Wiley-Liss, Inc. [source] Development of two cell culture systems from Asian seabass Lates calcarifer (Bloch)AQUACULTURE RESEARCH, Issue 1 2006Wazir S Lakra Abstract Two new cell culture systems namely epitheloid cells of Lates (LCE) and fibroblastic cells of Lates (LCF) have been developed from fry and fingerling of the economically important brackishwater fish Lates calcarifer. Primary cultures were initiated by explant technique using caudal fin of fingerling and whole body tissue of the fry. The nutritional requirements and the growth pattern in response to different culture environment were similar for the two cell cultures. The culture medium used was Leibovitz-15 supplemented with 20% fetal bovine serum (FBS) and 1% fish serum. The LCE comprised of epithelioid cells and LCF cells were fibroblastic. With a split ratio of 1:2, the confluency of cells was attained in 8,10 days at an incubation temperature of 28°C. The cells were found to grow well in a wide range of temperature (24,32°C) and stable at 20 and 36°C. The growth rate of LCF and LCE cells increased proportionately with the concentration of FBS from 5% to 20%. A decrease of serum level to 10% after eight subcultures produced no apparent change in cell morphology and growth rate. The viability of cells was found to be 70% when revived after a month of storage in liquid nitrogen (,196°C). [source] Pinusolide and 15-methoxypinusolidic acid attenuate the neurotoxic effect of staurosporine in primary cultures of rat cortical cellsBRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2007K A Koo Background and purpose: Apoptosis is a fundamental process required for neuronal development but also occurs in most of the common neurodegenerative disorders. In an attempt to obtain an anti-apoptotic neuroprotective compound from natural products, we isolated the diterpenoids, pinusolide and 15-MPA, from B. orientalis and investigated their neuroprotective activity against staurosporine (STS) -induced neuronal apoptosis. In addition, we determined the anti-apoptotic mechanism of these compounds in rat cortical cells. Experimental approach: Primary cultures of rat cortical cells injured by STS were used as an in vitro assay system. Cells were pretreated with pinusolide or 15-MPA before exposure to STS. Anti-apoptotic activities were evaluated by the measurement of cytoplasmic condensation and nuclear fragmentation. The levels of cellular peroxide, malondialdehyde (MDA) and [Ca2+]i, as well as the activities of superoxide dismutase (SOD) and caspase-3/7, were measured. Key results: Pinusolide and 15-MPA, at a concentration of 5.0 ìM, reduced the condensed nuclei and rise in [Ca2+]i that accompanies apoptosis induced by 100 nM STS. Pinusolide and 15-MPA also protected the cellular activity of SOD, an antioxidative enzyme reduced by STS insult. Furthermore, the overproduction of reactive oxygen species and lipid peroxidation induced by STS was significantly reduced in pinusolide and 15-MPA treated cells. In addition, pinusolide and 15-MPA inhibited STS-induced caspase-3/7 activation. Conclusions and Implications: These results show that pinusolide and 15-MPA protect neuronal cells from STS-induced apoptosis, probably by preventing the increase in [Ca2+]i and cellular oxidation caused by STS, and indicate that they could be used to treat neurodegenerative diseases. British Journal of Pharmacology (2007) 150, 65,71. doi:10.1038/sj.bjp.0706944 [source] NV-128, a novel isoflavone derivative, induces caspase-independent cell death through the Akt/mammalian target of rapamycin pathwayCANCER, Issue 14 2009Ayesha B. Alvero MD Abstract BACKGROUND: Resistance to apoptosis is 1 of the key events that confer chemoresistance and is mediated by the overexpression of antiapoptotic proteins, which inhibit caspase activation. The objective of this study was to evaluate whether the activation of an alternative, caspase-independent cell death pathway could promote death in chemoresistant ovarian cancer cells. The authors report the characterization of NV-128 as an inducer of cell death through a caspase-independent pathway. METHODS: Primary cultures of epithelial ovarian cancer (EOC) cells were treated with increasing concentration of NV-128, and the concentration that caused 50% growth inhibition (GI50) was determined using a proprietary assay. Apoptotic proteins were characterized by Western blot analyses, assays that measured caspase activity, immunohistochemistry, and flow cytometry. Protein-protein interactions were determined using immunoprecipitation. In vivo activity was measured in a xenograft mice model. RESULTS: NV-128 was able to induce significant cell death in both paclitaxel-resistant and carboplatin-resistant EOC cells with a GI50 between 1 ,g/mL and 5 ,g/mL. Cell death was characterized by chromatin condensation but was caspase-independent. The activated pathway involved the down-regulation of phosphorylated AKT, phosphorylated mammalian target of rapamycin (mTOR), and phosphorylated ribosomal p70 S6 kinase, and the mitochondrial translocation of beclin-1 followed by nuclear translocation of endonuclease G. CONCLUSIONS: The authors characterized a novel compound, NV-128, which inhibits mTOR and promotes caspase-independent cell death. The current results indicated that inhibition of mTOR may represent a relevant pathway for the induction of cell death in cells resistant to the classic caspase-dependent apoptosis. These findings demonstrate the possibility of using therapeutic drugs, such as NV-128, which may have beneficial effects in patients with chemoresistant ovarian cancer. Cancer 2009. © 2009 American Cancer Society. [source] The action of pro-inflammatory cytokines on retinal endothelial cell barrier permeability: protective effect of corticosteroidsACTA OPHTHALMOLOGICA, Issue 2008AF AMBROSIO Purpose The pro-inflammatory cytokines interleukin-1, (IL-1,) and tumor necrosis factor-alpha (TNF-,) were found to be increased in the vitreous of diabetic patients and in diabetic rat retinas, and increased cytokine levels were correlated with elevated retinal vascular permeability. In this work, we investigated the mechanisms underlying IL-1,- and TNF-,-induced retinal endothelial cell permeability and evaluated the ability of a glucocorticoid, dexamethasone (DEX), to prevent changes in permeability. Methods Primary cultures of bovine retinal endothelial cells (BRECs) were grown on transwell filters and exposed to IL-1, and TNF-,. BRECs permeability to 70 kDa RITC-dextran was measured. The content and localization of tight junction proteins was assessed by Western blotting and immunocytochemistry. Results IL-1, and TNF-, increased retinal endothelial cell permeability in a concentration- and time-dependent manner, but TNF-, was more effective (increased permeability at a lower dose and shorter time-point). The increase in permeability was not due to changes in cell viability. IL-1, and TNF-, altered ZO-1 and claudin-5 content. TNF-, also decreased ZO-1 staining at the cell border. Pre-treatment with DEX prevented TNF-,-induced cell permeability, and the protective effect of DEX was partially abolished by the glucocorticoid receptor antagonist RU486. Conclusion These data demonstrate that TNF-, and IL-1, potently induce endothelial cell permeability through alterations in tight junctions. Also, the study supports the potential therapeutic use of glucocorticoids to reduce retinal vascular permeability. Support: FCT (Portugal), NIH, JDRF and Allergan [source] Vascular smooth muscle cell phenotypic modulation in culture is associated with reorganisation of contractile and cytoskeletal proteinsCYTOSKELETON, Issue 3 2001Nathalie F. Worth Abstract Smooth muscle cells (SMC) exhibit a functional plasticity, modulating from the mature phenotype in which the primary function is contraction, to a less differentiated state with increased capacities for motility, protein synthesis, and proliferation. The present study determined, using Western analysis, double-label immunofluorescence and confocal microscopy, whether changes in phenotypic expression of rabbit aortic SMC in culture could be correlated with alterations in expression and distribution of structural proteins. "Contractile" state SMC (days 1 and 3 of primary culture) showed distinct sorting of proteins into subcellular domains, consistent with the theory that the SMC structural machinery is compartmentalised within the cell. Proteins specialised for contraction (,-SM actin, SM-MHC, and calponin) were highly expressed in these cells and concentrated in the upper central region of the cell. Vimentin was confined to the body of the cell, providing support for the contractile apparatus but not co-localising with it. In line with its role in cell attachment and motility, ,-NM actin was localised to the cell periphery and basal cortex. The dense body protein ,-actinin was concentrated at the cell periphery, possibly stabilising both contractile and motile apparatus. Vinculin-containing focal adhesions were well developed, indicating the cells' strong adhesion to substrate. In "synthetic" state SMC (passages 2,3 of culture), there was decreased expression of contractile and adhesion (vinculin) proteins with a concomitant increase in cytoskeletal proteins (,-non-muscle [NM] actin and vimentin). These quantitative changes in structural proteins were associated with dramatic changes in their distribution. The distinct compartmentalisation of structural proteins observed in "contractile" state SMC was no longer obvious, with proteins more evenly distributed throughout the cytoplasm to accommodate altered cell function. Thus, SMC phenotypic modulation involves not only quantitative changes in contractile and cytoskeletal proteins, but also reorganisation of these proteins. Since the cytoskeleton acts as a spatial regulator of intracellular signalling, reorganisation of the cytoskeleton may lead to realignment of signalling molecules, which, in turn, may mediate the changes in function associated with SMC phenotypic modulation. Cell Motil. Cytoskeleton 49:130,145, 2001. © 2001 Wiley-Liss, Inc. [source] Murine mesenchymal stem cells isolated by low density primary culture systemDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 6 2006Mohamadreza Baghaban Eslaminejad Murine mesenchymal stem cells (mMSC) and the difficult task of isolation and purification of them have been the subject of rather extensive investigation. The present study sought to isolate these cells from two different mouse strains, one outbred and the other inbred, primarily through a relatively simple but novel approach, the most important feature of which was the low density primary culture of bone marrow cells. For this purpose, mononuclear cells from either NMRI or BALB/c bone marrow were plated at about 500 cells per well of 24-well plates and incubated for 7 days. At this point, the fibroblastic clones that had emerged were pooled together and expanded through several subcultures. To investigate the mesenchymal nature, we differentiated the cells into the osteoblastic, chondrocytic and adipocytic lineages in different subcultures up to passage 10. According to the results, 1 week after culture initiation, several clones each comprising several fibroblastic cells appeared in each plate. The cells from different passages were capable of differentiating into corresponding skeletal tissues. In the present investigation, the best culture condition for maximum proliferation and also the expression of certain surface marker on isolated cells were examined. In this term the two murine strains showed some differences. [source] Runx3 controls growth and differentiation of gastric epithelial cells in mammalsDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 1 2006Hiroshi Fukamachi Runx3 is a transcription factor expressed by gastric epithelial cells. In the Runx3,/, mouse, gastric epithelia exhibited hyperplasia, and epithelial apoptosis was suppressed. By analyzing growth of the epithelial cells in primary culture, we found that Runx3,/, gastric epithelial cells are less sensitive to the growth-inhibitory and apoptosis-inducing activities of TGF-,, suggesting that Runx3 is a major growth regulator of gastric epithelial cells by regulating their response to TGF-,. We also found that Runx3 plays an important role in the control of gastric epithelial differentiation. When subcutaneously implanted into nude mice, Runx3,/, gastric epithelial cells formed tumors in which some cells differentiated into intestinal-type cells. Clonal analysis showed that gastric epithelial cells transdifferentiate into intestinal-type cells in the tumor. Considering that gastric epithelial differentiation is very stable, and that intestinal-type cells never differentiate in the mouse stomach, it is remarkable that gastric epithelial cells transdifferentiate into intestinal-type cells. We conclude that Runx3 is deeply involved in the control of both growth and differentiation of gastric epithelial cells. The role of Runx3 in the specification of gastric epithelial cells is discussed. [source] Normal dendrite growth in Drosophila motor neurons requires the AP-1 transcription factorDEVELOPMENTAL NEUROBIOLOGY, Issue 10 2008Cortnie L. Hartwig Abstract During learning and memory formation, information flow through networks is regulated significantly through structural alterations in neurons. Dendrites, sites of signal integration, are key targets of activity-mediated modifications. Although local mechanisms of dendritic growth ensure synapse-specific changes, global mechanisms linking neural activity to nuclear gene expression may have profound influences on neural function. Fos, being an immediate-early gene, is ideally suited to be an initial transducer of neural activity, but a precise role for the AP-1 transcription factor in dendrite growth remains to be elucidated. Here we measure changes in the dendritic fields of identified Drosophila motor neurons in vivo and in primary culture to investigate the role of the immediate-early transcription factor AP-1 in regulating endogenous and activity-induced dendrite growth. Our data indicate that (a) increased neural excitability or depolarization stimulates dendrite growth, (b) AP-1 (a Fos, Jun hetero-dimer) is required for normal motor neuron dendritic growth during development and in response to activity induction, and (c) neuronal Fos protein levels are rapidly but transiently induced in motor neurons following neural activity. Taken together, these results show that AP-1 mediated transcription is important for dendrite growth, and that neural activity influences global dendritic growth through a gene-expression dependent mechanism gated by AP-1. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008 [source] Mixed primary culture and clonal analysis provide evidence that NG2 proteoglycan-expressing cells after spinal cord injury are glial progenitorsDEVELOPMENTAL NEUROBIOLOGY, Issue 7 2007Soonmoon Yoo Abstract NG2+ cells in the adult rat spinal cord proliferate after spinal cord injury (SCI) and are postulated to differentiate into mature glia to replace some of those lost to injury. To further study these putative endogenous precursors, tissue at 3 days after SCI or from uninjured adults was dissociated, myelin partially removed and replicate cultures grown in serum-containing or serum-free medium with or without growth factors for up to 7 days in vitro (DIV). Cell yield after SCI was 5,6 times higher than from the normal adult. Most cells were OX42+ microglia/macrophages but there were also more than twice the normal number of NG2+ cells. Most of these coexpressed A2B5 or nestin, as would be expected for glial progenitors. Few cells initially expressed mature astrocyte (GFAP) or oligodendrocyte (CC1) markers, but more did at 7 DIV, suggesting differentiation of glial precursors in vitro. To test the hypothesis that NG2+ cells after SCI express progenitor-like properties, we prepared free-floating sphere and single cell cultures from purified suspension of NG2+ cells from injured spinal cord. We found that sphere cultures could be passaged in free-floating subcultures, and upon attachment the spheres clonally derived from an acutely purified single cell differentiated into oligodendrocytes and rarely astrocytes. Taken together, these data support the hypothesis that SCI stimulates proliferation of NG2+ cells that are glial progenitor cells. Better understanding the intrinsic properties of the NG2+ cells stimulated by SCI may permit future therapeutic manipulations to improve recovery after SCI. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007. [source] Liposome-mediated transfection of mature taste cellsDEVELOPMENTAL NEUROBIOLOGY, Issue 1 2005Ana Marie Landin Abstract The introduction and expression of exogenous DNA in neurons is valuable for analyzing a range of cellular and molecular processes in the periphery, e.g., the roles of transduction-related proteins, the impact of growth factors on development and differentiation, and the function of promoters specific to cell type. However, sensory receptor cells, particularly chemosensory cells, have been difficult to transfect. We have successfully introduced plasmids expressing green and Discosoma Red fluorescent proteins (GFP and DsRed) into rat taste buds in primary culture. Transfection efficiency increased when delaminated taste epithelium was redigested with fresh protease, suggesting that a protective barrier of extracellular matrix surrounding taste cells may normally be present. Because taste buds are heterogeneous aggregates of cells, we used ,-gustducin, neuronal cell adhesion molecule (NCAM), and neuronal ubiquitin carboxyl terminal hydrolase (PGP9.5), markers for defined subsets of mature taste cells, to demonstrate that liposome-mediated transfection targets multiple taste cell types. After testing eight commercially available lipids, we identified one, Transfast, that is most effective on taste cells. We also demonstrate the effectiveness of two common "promiscuous" promoters and one promoter that taste cells use endogenously. These studies should permit ex vivo strategies for studying development and cellular function in taste cells. © 2005 Wiley Periodicals, Inc. J. Neurobiol, 2005 [source] Dopaminergic signalling in the rodent neonatal suprachiasmatic nucleus identifies a role for protein kinase A and mitogen-activated protein kinase in circadian entrainmentEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2002Irina L. Schurov Abstract The circadian clock of the suprachiasmatic nuclei (SCN) of perinatal rodents is entrained by maternally derived cues. The SCN of neonatal Syrian hamsters express high-affinity D1 dopamine receptors, and the circadian activity,rest cycle of pups can be entrained by maternal injection of dopaminergic agonists. The present study sought to characterize the intracellular pathways mediating dopaminergic signalling in neonatal rodent SCN. Both dopamine and the D1 agonist SKF81297 caused a dose-dependent increase in phosphorylation of the transcriptional regulator Ca2+/cyclic AMP response element (CRE) binding protein (CREB) in suprachiasmatic GABA-immunoreactive (-IR) neurons held in primary culture. The D1 antagonist SCH23390 blocked this effect. Dopaminergic induction of pCREB-IR in GABA-IR neurons was also blocked by a protein kinase A (PKA) inhibitor, 5,24, and by the MAPK inhibitor, PD98059, whereas KN-62, an inhibitor of Ca2+/calmodulin-dependent (CAM) kinase II/IV was ineffective. Treatment with NMDA increased the level of intracellular Ca2+ in the cultured primary SCN neurons in Mg2+ -free medium, but SKF81297 did not. Blockade of CaM kinase II/IV with KN-62 inhibited glutamatergic induction of pCREB-IR in GABA-IR neurons, whereas 5,24 was ineffective, confirming the independent action of Ca2+ - and cAMP-mediated inputs on pCREB. SKF81297 caused an increase in pERK-IR in SCN cells, and this was blocked by 5,24, indicative of activation of MAPK via D1/cAMP. These results demonstrate that dopaminergic signalling in the neonatal SCN is mediated via the D1-dependent activation of PKA and MAPK, and that this is independent of the glutamatergic regulation via Ca2+ and CaM kinase II/IV responsible for entrainment to the light/dark cycle. [source] Dual effect of ecdysone on adult cricket mushroom bodiesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2000Myriam Cayre Abstract Mushroom bodies, which are the main integrative centre for insect sensorial information, play a critical role in associative olfactory learning and memory. This paired brain structure contains interneurons grouped in a cortex, sending their axons into organized neuropiles. In the house cricket (Acheta domesticus) brain, persistent neuroblasts proliferate throughout adult life. Juvenile hormone (JH) has been shown to stimulate this proliferation [Cayre, M., Strambi, C. & Strambi, A. (1994) Nature, 368, 57,59]. In the present study, the effect of morphogenetic hormones on mushroom body cells maintained in primary culture was examined. Whereas JH did not significantly affect neurite growth, ecdysone significantly stimulated neurite elongation. Moreover, ecdysone also acted on neuroblast proliferation, as demonstrated by the reduced number of cells labelled with 5-bromodeoxyuridine following ecdysone application. Heterospecific antibodies raised against ecdysone receptor protein and ultraspiracle protein, the two heterodimers of ecdysteroid receptors, showed positive immunoreactivity in nervous tissue extracts and in nuclei of mushroom body cells, indicating the occurrence of putative ecdysteroid receptors in cricket mushroom body cells. These data indicate a dual role for ecdysone in adult cricket mushroom bodies: this hormone inhibits neuroblast proliferation and stimulates interneuron differentiation. These results suggest that a constant remodelling of mushroom body structure could result from physiological changes in hormone titres during adult life. [source] Chlorotoxin-sensitive Ca2+ -activated Cl, channel in type R2 reactive astrocytes from adult rat brainGLIA, Issue 4 2003Stanislava Dalton Abstract Astrocytes express four types of Cl, or anion channels, but Ca2+ -activated Cl, (ClCa) channels have not been described. We studied Cl, channels in a morphologically distinct subpopulation (, 5% of cells) of small (10,12 ,m, 11.8 ± 0.6 pF), phase-dark, GFAP-positive native reactive astrocytes (NRAs) freshly isolated from injured adult rat brains. Their resting potential, ,57.1 ± 4.0 mV, polarized to ,72.7 ± 4.5 mV with BAPTA-AM, an intracellular Ca2+ chelator, and depolarized to ,30.7 ± 6.1 mV with thapsigargin, which mobilizes Ca2+ from intracellular stores. With nystatin-perforated patch clamp, thapsigargin activated a current that reversed near the Cl, reversal potential, which was blocked by Cl, channel blockers, 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) and Zn2+, by I, (10 mM), and by chlorotoxin (EC50 = 47 nM). With conventional whole-cell clamp, NPPB- and Zn2+ -sensitive currents became larger with increasing [Ca2+]i (10, 150, 300 nM). Single-channel recordings of inside-out patches confirmed Ca2+ sensitivity of the channel and showed open-state conductances of 40, 80, 130, and 180 pS, and outside-out patches confirmed sensitivity to chlorotoxin. In primary culture, small phase-dark NRAs developed into small GFAP-positive bipolar cells with chlorotoxin-sensitive ClCa channels. Imaging with biotinylated chlorotoxin confirmed the presence of label in GFAP-positive cells from regions of brain injury, but not from uninjured brain. Chlorotoxin-tagged cells isolated by flow cytometry and cultured up to two passages exhibit positive labeling for GFAP and vimentin, but not for prolyl 4-hydroxylase (fibroblast), A2B5 (O2A progenitor), or OX-42 (microglia). Expression of a novel chlorotoxin-sensitive ClCa channel in a morphologically distinct subpopulation of NRAs distinguishes these cells as a new subtype of reactive astrocyte. GLIA 42:325,339, 2003. © 2003 Wiley-Liss, Inc. [source] Plasticity in the adult rat pancreas: Transdifferentiation of exocrine to hepatocyte-like cells in primary cultureHEPATOLOGY, Issue 6 2004Jessy Lardon Under certain experimental conditions, hepatocytes can arise in the pancreas. It has been suggested that the pancreas retains a source of hepatocyte progenitor cells. However, such cells have not been yet identified in the adult pancreas. We describe here the transdifferentiation of primary rat pancreatic exocrine cells into hepatocyte-like cells during 5 days of tissue culture in the presence of dexamethasone (DX). Using reverse-transcription polymerase chain reaction and immunocytochemistry, it was observed that DX treatment induced albumin RNA and protein expression in the cells. Coexpression of albumin and amylase, and the absence of cell proliferation, demonstrated a direct transdifferentiation of acinar cells to hepatocytic cells. CCAAT enhancer-binding protein-ß protein, a liver-enriched transcription factor that is considered to be the master switch in pancreatohepatic transdifferentiation, and ,-fetoprotein were markedly upregulated in the cells after treatment with DX. We compared transcriptional profiles of freshly isolated exocrine cells and DX-treated cells using oligonucleotide microarrays and found that multiple liver-specific genes are induced along with albumin, and that certain pancreatic genes are downregulated in the DX-treated cells. In conclusion, these observations support the notion of plasticity in the adult pancreas and that exocrine cells can be reprogrammed to transdifferentiate into other cell types such as hepatocytes. (HEPATOLOGY 2004;39:1499,1507.) [source] A novel mechanism for mitogenic signaling via pro,transforming growth factor , within hepatocyte nucleiHEPATOLOGY, Issue 6 2002Bettina Grasl-Kraupp Transforming growth factor (TGF) ,, an important mediator of growth stimulation, is known to act via epidermal growth factor receptor (EGF-R) binding in the cell membrane. Here we show by immunohistology, 2-dimensional immunoblotting, and mass spectrometry of nuclear fractions that the pro-protein of wild-type TGF-, occurs in hepatocyte nuclei of human, rat, and mouse liver. Several findings show a close association between nuclear pro-TGF-, and DNA synthesis. (1) The number of pro-TGF-,+ nuclei was low in resting liver and increased dramatically after partial hepatectomy and after application of hepatotoxic chemicals or the primary mitogen cyproterone acetate (CPA); in any case, S phase occurred almost exclusively in pro-TGF-,+ nuclei. The same was found in human cirrhotic liver. (2) In primary culture, 7% of hepatocytes synthesized pro-TGF-,, which then translocated to the nucleus; 70% of these nuclei subsequently entered DNA replication, whereas only 2% of pro-TGF-,, hepatocytes were in S phase. (3) The frequency of hepatocytes coexpressing pro-TGF-, and DNA synthesis was increased by the hepatomitogens CPA or prostaglandin E2 and was decreased by the growth inhibitor TGF-,1. (4) Treatment with mature TGF-, increased DNA synthesis exclusively in pro-TGF-,, hepatocytes, which was abrogated by the EGF-R tyrosine kinase inhibitor tyrphostin A25. In conclusion, TGF-, gene products may exert mitogenic effects in hepatocytes via 2 different signaling mechanisms: (1) the "classic" pathway of mature TGF-, via EGF-R in the membrane and (2) a novel pathway involving the presence of pro-TGF-, in the nucleus. [source] Circulating EM66 is a highly sensitive marker for the diagnosis and follow-up of pheochromocytomaINTERNATIONAL JOURNAL OF CANCER, Issue 8 2006Johann Guillemot Abstract We have previously demonstrated that measurement of tissue concentration of the novel secretogranin II-derived peptide EM66 may help to discriminate between benign and malignant pheochromocytomas. The aim of the present study was to characterize EM66 in plasma and urine of healthy volunteers and pheochromocytoma patients, in order to further evaluate the usefulness of this peptide as a circulating marker for the management of the tumors. HPLC analysis of plasma and urine samples demonstrated that the EM66-immunoreactive material coeluted with the recombinant peptide. In healthy volunteers, plasma and urinary EM66 levels were, respectively, 2.6 (1.9,3.7) ng/ml and 2.9 (1.9,4.6) ng/ml. In patients with pheochromocytoma, plasma EM66 levels were 10-fold higher than those of healthy volunteers (26.9 (7.3,44) ng/ml), and returned to normal values after removal of the tumor. In contrast, urinary EM66 levels were not significantly different from those of healthy volunteers (3.2 (2.2,3.9) ng/ml). Measurement of total or free plasma metanephrines and 24 hr urinary metanephrines in our series of patients revealed that these tests, taken separately, are less sensitive than the EM66 determination. Pheochromocytes in primary culture secreted high levels of EM66, suggesting that the chromaffin tumor was actually responsible for the increased plasma peptide concentrations in the patients. These data indicate that EM66 is secreted in the general circulation and that elevated plasma EM66 levels are correlated with the occurrence of pheochromocytoma. Thus, EM66 is a sensitive plasma marker that should be considered as a complementary tool in the management of pheochromocytoma. © 2005 Wiley-Liss, Inc. [source] Rietveld structure and in vitro analysis on the influence of magnesium in biphasic (hydroxyapatite and ,-tricalcium phosphate) mixturesJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2009S. Kannan Abstract The structure of two different Mg-substituted biphasic (HAP and ,-TCP) mixtures along with the biphasic mixtures without substituted Mg2+ was investigated using Rietveld refinement technique. The substituted Mg2+ was found in the ,-TCP phase and its influence on the composition has led to an increase in HAP content of Mg-containing biphasic mixtures when compared with the HAP content detected in pure biphasic mixtures. The refined structural parameters of Ca10(PO4)6(OH)2 and ,-Ca3(PO4)2 confirmed that all the investigated compositions have crystallized in the corresponding hexagonal (space group P63/m) and rhombohedral (space group R3c) structures. The substitution of lower sized magnesium was found preferentially incorporated at the sixfold-coordinated Ca (5) site of ,-TCP, which is due to the strong Ca (5)·O interaction among all the five different Ca sites of ,-Ca3(PO4)2. The in vitro tests using primary culture of osteoblasts showed that all the tested samples are biocompatible and promising materials for in vivo studies. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009 [source] | |||||||||||||||||||||||||||||||||||||