bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of tumor necrosis factor‐α and interferon‐γ on the growth of a human salivary gland cell line
Authors: Wu Ava J. , Kurrasch Regina H. , Katz Joseph , Fox Philip C. , Baum Bruce J. , Atkinson Jane C. 
Published: February 2005

AbstractInterferon‐γ (IFN‐γ) is a product of activated T‐lymphocytes, and tumor necrosis factor‐α (TNF‐α) is a product of both lymphocytes and macrophages. These cell types are often present at sites of tissue damage secondary to chronic infection or autoimmune disease. The purpose of this study was to characterize the effects of TNF‐α and IFN‐γ on a human submandibular gland epithelial cell line (HSG). IFN‐γ caused a concentration‐dependent decrease in HSG cell growth (∼70% in 6 days). Conversely, TNF‐α alone had little effect on the growth of these cells. When these cytokines were added in combination (20 units/ml TNF‐α and 1,000 units/ml of IFN‐γ), there was a synergistic antiproliferative effect; no apparent cell growth was observed. The cytokine‐induced antiproliferative effect was reversible. After the apparent cessation of cell growth for 3–6 days, removal of the cytokines permitted complete growth recovery. Further, cells that recovered and exhibited growth patterns that were similar to control cells remained susceptible to the antiproliferative effects of the cytokines. Flow cytometry revealed that the percentage of cells in G0/G1 with the combination of cytokines was significantly increased by 24 h. The antiproliferative effect of IFN‐γ alone and that of IFN‐γ and TNF‐α in combination were blocked completely using an antibody to the IFN‐γ receptor. A hypothesized mechanism of tissue damage in autoimmune inflammatory disorders is via up‐regulation of cell surface markers such as intercellular adhesion molecule type I (ICAM‐1) and histocompatibility antigen HLA‐DR which can exacerbate the inflammatory process. Treatment of HSG cells with IFN‐γ, with or without TNF‐α, resulted in increased levels of ICAM‐1 and the acquisition of HLA‐DR expression. These aggregate data suggest that IFN‐γ alone can regulate the expression of cell surface markers involved in the inflammatory process as well as cause a potent yet reversible inhibition of HSG cell growth that is modulated by the presence of TNF‐α. © 1994 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Overexpression of manganous superoxide dismutase (MnSOD) in pulmonary endothelial cells confers resistance to hyperoxia
Authors: Lindau‐Shepard Barbara , Shaffer Jacquelin B. , Del Vecchio Peter J. 
Published: February 2005

AbstractTreatment of cells or organisms with agents that increase the expression of MnSOD confers resistance to certain types of oxidative damage. However, since these treatments also affect other cellular systems with antioxidant capabilities, the role of MnSOD remains uncertain. To better determine whether increased MnSOD expression confers increased resistance to oxidant stress, a eukaryotic expression vector harboring a mouse MnSOD cDNA was constructed. Bovine lung microvessel endothelial cells were co‐transfected with the MnSOD expression vector and pSV2‐neo, which contains the neo' gene and provides a dominant selectable marker. Control clones were generated by transfecting the cells with pSV2‐neo alone. Stably transfected cell lines were selected and cell lines overexpressing MnSOD were confirmed by Northern blotting, immunoblot analysis, and activity gels. The activities of copper/zinc superoxide dismutase, catalase, and glutathione peroxidase were examined, and no increase in activity of any of these enzymes was detected. Cells were exposed to hyperoxic challenge by treatment with 95% O2 and 5% CO2 for 24 h. Viability was assessed by a clonogenic assay. The cell lines that overexpressed MnSOD showed a twofold increase in survival compared to control cells. These results demonstrate a significant resistance to hyperoxia induced oxidative stress in endothelial cells overexpressing MnSOD. © 1994 Wiley‐Liss, Inc.
Reorganization of endothelial cord‐like structures on basement membrane complex (Matrigel): Involvement of transforming growth factor β1
Authors: Kuzuya Masafumi , Kinsella James L. 
Published: February 2005

AbstractThe formation of capillary‐like network structures by cultured vascular endothelial cells on reconstituted basement membrane matrix, Matrigel, models endothelial cell differentiation, the final step of angiogenesis (Kubota et al., 1988; Grant et al., 1989). When endothelial cells derived from bovine aorta and brain capillaries were plated on Matrigel, DNA synthesis was suppressed and a network of capillary‐like structures rapidly formed in 8–12 h. With time, the network broke down, resulting in dense cellular cords radiating from multiple cellular clusters in 16–24 h. Finally, multicellular aggregates of cells were formed as the network underwent further retraction. Network regression was prevented when either dithiothreitol (DTT) or anti‐TG F‐β1 antibodies were added during the assay. The addition of exogenous TGF‐β1 promoted the regression of endothelial cells into the clusters. This response to TGF‐β1 was blocked by potent serine threonine protein kinase inhibitors, H‐7 and HA 100. TGF‐β1 was released from polymerized Matrigel by incubation with Dulbecco's modified eagle's medium (DMEM) in the absence of cells. The Matrigel‐conditioned DMEM inhibited endothelial DNA synthesis even in the presence of anti‐TGF‐β1 antibodies. These results suggest that TGF‐β1 and possibly other soluble factors from Matrigel may be important for differentitation and remodeling of endothelial cells in a capillary network with possible implications for wound healing and development. © 1994 Wiley‐Liss, Inc.This article is a US Government work and as such, is in the public domain in the United States of America
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Differential effects of transforming growth factor‐β1 on distinct developmental stages of murine megakaryocytopoiesis
Authors: Jackson Heather , Williams Neil , Westcott Keith R. , Green Ralph 
Published: February 2005

AbstractThe effect of transforming growth factor‐β1 (TGFβ1) on three developmental stages of megakaryocytopoiesis was investigated. Using a murine bone marrow agar culture system, titrated doses of TGFβ1 were added to cultures assaying primitive high proliferative megakaryocyte progenitors, committed megakaryocyte precursors, and nondividing, endoreduplicating megakaryocytes. The growth of high proliferative megakaryocyte colony‐forming cells (HPP‐CFU‐Mk) that require the growth factors interleukins‐1, 3 and 6 (IL‐1 + IL‐3 + IL‐6) for colony detection was abrogated by the addition of 1 ng TGFβ1/ml. The sensitivity of committed megakaryocyte progenitors (colony‐forming unit‐megakaryocyte, CFU‐Mk) to TGFβ1 depended on the growth factor combination. TGFβ1 (1 ng/ml) completely inhibited megakaryocyte colony formation from CFU‐Mk only in cultures stimulated by low doses of IL‐3. TGFβ1 (> 10 ng/ml) could only marginally inhibit megakaryocyte colony forrmation generated in the presence of either high doses of IL‐3 or the combination of low dose IL‐3 + IL‐6. TGFβ1 inhibited both IL‐3‐dependent and IL‐6‐dependent megakaryocyte growth but tenfold higher doses of TGFβ1 were required to inhibit growth generated by the combination of IL‐3 + IL‐6. The data showed that the capacity of TGFβ1 to inhibit distinct differentiation stages of the megakaryocytopoietic lineage depended on the concentration and combination of growth factors involved. © 1994 Wiley‐Liss, Inc.
Induction of Bcl‐2 gene expression by intercellular information from hemopoietic supportive stromal cells to DA‐1 cells
Authors: Takashita Emi , Sugimoto Kenkichi , Adachi Yasuhiro , Mori Kazuhiro J. 
Published: February 2005

AbstractWhen Interleukin‐3 (IL‐3) dependent DA‐1 cells were cultured on hemopoietic supportive stromal cells (MS‐5), DA‐1 cells survived and proliferated in the absence of detectable IL‐3. Although IL‐3 was not produced by the MS‐5 cells, their production of granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) was increased when they were co‐cultured with DA‐1 cells. This suggests that DA‐1 cells transmit signals to stromal cells that enhance growth factor(s) production. Expression of bcl‐2 by DA‐1 cells was induced when they were co‐cultured with MS‐5 cells, suggesting that DA‐1 cells express bcl‐2 strongly in response to a signal produced by MS‐5 cells. These data indicate the existence of a two‐way interaction between DA‐1 cells and hemopoietic supportive stromal cells. © 1994 Wiley‐Liss, Inc.
Endothelin secretion is regulated by cyclic AMP and phosphatase 2A in endothelial cells
Authors: Magnusson Andres , Halldorsson Haraldur , Thorgeirsson Gudmundur , Kjeld Matthias 
Published: February 2005

AbstractEndothelin is a 21 amino acid peptide secreted by endothelial cells and is the most potent vasoconstrictor known. The present study examines regulatory mechanisms of endothelin secretion, focusing on the role of protein phosphorylation. Endothelin secretion was measured by radioimmunoassay in primary cultures of human umbilical vein endothelial cells. While treatment that raised cAMP levels reduced the basal endothelin secretion rate, agents that elevated cGMP had no effect. Downregulation or inhibition of protein kinase C resulted in decreased endothelin secretion, suggesting that protein kinase C regulates endothelin secretion in the opposite direction to cAMP dependent protein kinases Okadaic acid, at concentrations that selectively inhibit protein phosphatases 2A, reduced the endothelin secretion and the effects of okadaic acid and db‐cAMP were additive. Endothelin production was stimulated by fetal calf serum and by the protein kinase inhibitor 1‐(5‐isoquinolinylsulphonyl)‐2‐methylpiperazine (H7), but was inhibited by the calmodulin antagonist trifluoperazine. The present findings that regulators of cAMP‐dependent protein kinases, protein kinase C, calmodulin, and protein phosphatase 2A all affect endothelin secretion suggest that endothelin secretion is controlled by phosphorylation/dephosphorylation of as yet unidentified regulatory proteins within the cell. © 1994 Wiley‐Liss, Inc.
c‐Ha‐rasEJ transfection of rat aortic smooth muscle cells induces epidermal growth factor responsiveness and characteristics of a malignant phenotype
Authors: Sadhu D. N. , Lundberg M. S. , Burghardt R. C. , Ramos K. S. 
Published: February 2005

AbstractAlthough the role of several protooncogenes, including sis, myc, and myb in the regulation of growth and differentiation of vascular cells has been examined in some detail, limited information is available on the contribution of ras genes to these processes. In the present studies the influence of oncogenic ras transfection on the phenotypic expression of rat aortic smooth muscle cells (SMCs) was examined. Cultured rat aortic SMCs during early passage (P4) were transfected by lipofection with c‐Ha‐rasEJ in a pSV2 neo vector or with pSV2 neo vector alone. Stable transfectants were selected in G418 over a 6‐week period. Oncogene‐transfected cells (ras‐LF‐1) exhibited differences in morphology and growth pattern relative to vector controls (neo‐LF‐1), or naive SMCs, including the development of prominent processes and the appearance of focal cellular arrangements giving rise to latticelike structures. Southern analysis revealed multiple integration of oncogenic ras in ras LF‐1 cells. Transfection of c‐Ha‐rasEJ was associated with a twofold increase in p21 levels relative to pSV2 vector controls demonstrating that exogenous ras was expressed in these cells. Overexpression of ras p21 afforded SMCs a lower serum requirement for growth compared to vector controls, anchor‐age independent growth on soft agar, and acquisition of epidermal growth factor (EGF) responsiveness. Stimulation of serum‐deprived SMCs with 5% fetal bovine serum (FBS) increased steady‐state levels of c‐Ha‐ras mRNA in both ras‐LF‐1 and neo‐LF‐1 but ras induction was more pronounced in ras‐transfected cells. α‐smooth muscle (SM) actin gene expression was markedly reduced in ras‐transfected cells relative to vector controls. These results show that transfection of c‐Ha‐rasEJ into aortic SMCs induces an altered phenotypic state characterized by alterations in growth factor‐related signal transduction and tumorigenic potential. © 1994 Wiley‐Liss, Inc.
Osteogenic protein‐1, a bone morphogenic protein member of the TGF‐β superfamily, shares chemotactic but not fibrogenic properties with TGF‐β
Authors: Postlethwaite Arnold E. , Raghow Rajendra , Stricklin George , Ballou Leslie , Sampath T. Kuber 
Published: February 2005

AbstractWe have previously shown that recombinant human osteogenic protein‐1 (rhOP‐1), a bone morphogenetic protein member of the TGF‐β superfamily, can induce new bone formation when implanted with an appropriate carrier at subcutaneous sites in rats and can restore completely large diaphyseal segmental defects in laboratory animals. The role of OP‐1 in the early events of bone induction viz, chemotaxis of phagocytic leukocytes, and fibroblastic mesenchymal cells is currently unknown. In the present study, we examined the effect of rhOP‐1 on chemotaxis of phagocytic leukocytes (human neutrophils and monocytes) and fibroblastic mesenchymal cells (infant foreskin fibroblasts). Since OP‐1 is structurally related to TGF‐β1, we assessed the effects of OP‐1 on several other fibroblast functions (in addition to chemotaxis) known to be modulated by TGF‐β1. Our results demonstrated that rhOP‐1, like TGF‐β1, is a potent chemoattractant for human neutrophils, monocytes, and fibroblasts. However, in contrast to TGF‐β1, OP‐1 does not to stimulate fibroblast mitogenesis, matrix synthesis [collagen and hyaluronic acid (hyaluronan)], or production of tissue inhibitor of metalloproteinase (TIMP), i.e., fibroblast functions associated with fibrogenesis. These results clearly demonstrate a dichotomy between these two members of the TGF‐β superfamily with regard to fibrogenic effects on fibroblasts but a similarity in their chemotactic properties. © 1994 Wiley‐Liss, Inc.
Effect of membrane potential on surface Ca2+ receptor activation in rat osteoclasts
Authors: Shankar Vijai S. , Huang Christopher L.‐H. , Adebanjo Olugbenga , Simon Bruce , Alam A. S. M. Towhidul , Moonga Baljit S. , Pazianas Michael , Scott Roderick H. , Zaidi Mone 
Published: February 2005

AbstractOsteoclasts are known to possess a divalent cation‐sensitive receptor, the Ca2+ receptor (CaR). The latter monitors changes in the local Ca2+ concentration generated as a result of hydroxyapatite dissolution. CaR activation elevates cytosolic [Ca2+] and thereby inhibits osteoclastic bone resorption. Recent studies have used Ni2+ as a surrogate CaR agonist to elicit changes in cytosolic [Ca2+]. This article examines the effects of membrane potential changes on the kinetics of the cytosolic [Ca2+] signal resulting from such Ni2+‐induced CaR activation. Membrane potential was altered through variations in the extracellular [K+] in combination with applications of the K+ ionophore, valinomycin. Membrane potential changes were confirmed by independent electrophysiological patch clamp studies of whole osteoclasts. The application of valinomycin produced a distinct, sustained elevation of cytosolic [Ca2+] in single fura 2‐loaded cells, a “primary” response. This response was independent of valinomycin concentration (between 5 nM to 5 μM) and persisted in Ca2+‐free, EGTA‐containing solutions. It also persisted both in high (105 mM) and low (5 mM) extracellular [K+]. A gradual “secondary” elevation of cytosolic [Ca2+] then followed with the continued application of valinomycin, but this was eliminated by sequestering the extracellular [Ca2+] or by increasing extracellular [K+] from 5 to 105 mM. In a separate set of experiments, the presence of 5 μM [valinomycin]‐([K+] = 5 mM) prolonged the cytosolic [Ca2+] signal elicited by 50 μM‐[Ni2+] application. These prolonged kinetics persisted in low extracellular [Ca2+] (zero‐added Ca2+), but reverted to a rapid time‐course in the presence of 105 mM‐[K+] or at higher [Ni2+] (500 μM and 5 mM). The experiments thus indicate that membrane voltage modifies the kinetics of CaR activation by Ni2+ and therefore suggests that the CaR is an integral protein in the osteoclast surface membrane. © 1995 Wiley‐Liss, Inc.
Chloride is required for receptor‐mediated divalent cation entry in mesangial cells
Authors: Kremer Sidney G. , Zeng Wenjia , Hurst Roger , Ning Terri , Whiteside Catharine , Skorecki Karl L. 
Published: February 2005

AbstractAgonists which stimulate the inositol 1,4,5 trisphosphate ([1,4,5]‐IP3)‐dependent mobilization of Ca2+ from intracellular stores also stimulate entry of divalent cations across the cell membrane. Under appropriate experimental conditions, divalent cation entry across the cell membrane can be monitored as the rate at which the intracellular fluorescence of divalent cation indicators is quenched by the addition of Mn2+ to the extracellular medium. We report that addition of vasopressin to fura‐2‐loaded glomerular mesangial cells in culture markedly accelerated the rate at which Mn2+ quenched fura‐2 fluorescence at its Ca2+‐insensitive wavelength in the presence of extracellular NaCl, but that this quench response was attenuated when Cl− was removed from the extracellular medium by equimolar substitution with impermeant anions (gluconate, methanesulfonate, acetate, lactate). Similarly, loss of agonist‐induced quench also occurred when Cl− was substituted with gluconate in K+‐containing media. Addition of the Cl− channel inhibitor, 5‐nitro‐2‐(3‐phenylpropylaminobenzoic acid) (NPPB), also inhibited Mn2+‐induced quench of fura‐2 fluorescence following vasopressin addition. In contrast, in the presence of gramicidin to provide an alternate conductance pathway to accompany divalent cation entry, agonist‐dependent Mn2+ quench occurred even in the absence of extracellular Cl−, indicating that the requirement for Cl− was not the result of cotransport on a common transporter nor the result of Cl− serving as a necessary cofactor for divalent cation entry. A similar dependence on extracellular Cl− was observed for other Ca2+‐mobilizing agonists such as endothelin, as well as the intracellular Ca2+ ATPase inhibitor, thapsigargin. Extracellular Cl− dependence for agonist‐induced divalent cation entry was also reflected in a corresponding extracellular Cl− dependence for agonist‐induced mesangial cell contraction. It has been previously shown by ourselves (Kremer et al., 1992a, Am. J. Physiol., 262:F668–F678) and others that agonist‐stimulated calcium mobilization in mesangial cells is accompanied by inhibition of K+ conductance and increased Cl− conductance. Accordingly, we conclude that the current findings suggest that activation of Cl− conductance provides regulated charge compensation for receptor‐mediated divalent cation entry in response to Ca2+‐mobilizing vasoconstrictor agonists in mesangial cells. © 1995 Wiley‐Liss, Inc.
Mitotic cycle reactivation in terminally differentiated cells by adenovirus infection
Authors: Crescenzi Marco , Soddu Silvia , Tatò Franco 
Published: February 2005

AbstractDifferent cell types (e.g., neurons, skeletal and heart myocytes, adipocytes, keratinocytes) undergo terminal differentiation, in which acquisition of specialized functions entails definitive withdrawal from the cell cycle. Such cells are distinct from quiescent (reversibly growth‐arrested) cells, such as contact‐inhibited fibroblasts. Terminally differentiated cells can not be induced to proliferate by means of growth factor stimulation or transduction of cellular oncogenes. An important first step toward defining the molecular basis for such unresponsiveness is to find a practical means to overcome the proliferative block. Furthermore, determining whether terminally differentiated, postmitotic cells still retain a potential competence for proliferation that can be reactivated would have important theoretical and practical implications. To address these questions, we exploited the properties of adenoviruses. These viruses can infect postmitotic cells and express E1A, a powerful activator of proliferation in reversibly growth‐arrested cells. We infected terminally differentiated skeletal muscle cells and adipocytes with human adenovirus type 5 or 12, obtaining full reentry into the cell cycle, including DNA synthesis, mitosis, cytokinesis, and extended proliferation. Similar results were obtained with established cell lines and primary cells belonging to several species, from quail to humans. Genetic analysis indicated that the smaller splice product of E1A, E1A 12S, is sufficient to induce cell cycle reactivation in otherwise permanently nonmitotic cells. These results demonstrate that terminally differentiated cells retain proliferative potential and establish adenovirus as a convenient and powerful means to force such cells to reenter the cell cycle. © 1995 Wiley‐Liss, Inc.
Expression of a voltage‐dependent potassium current precedes fusion of human muscle satelite cells (myoblasts)
Authors: Widmer H. , Hamann M. , Baroffio A. , Bijlenga P. , Bader C. R. 
Published: February 2005

AbstractUsing the whole‐cell recording patch clamp tehnique in clonal cultures of human muscle satellite cells (SC), we studied a voltage‐gated potassium current analogous to the delayed rectifier current (Ikdr) described in adult human skeletal muscle. This current was absent in proliferating SC cultured in a growth medium containing 15% serum, except when the SC approached the end of their replicative life (between 77 and 124 days in culture); at that time, approximately 50% of the SC possessed Ikdr In contrast, Ikdr was expressed within less than 4 days in approximately 70% of the SC cultured in a serum‐free medium (SFM) and within 24 h in differetiating medium. We belive that Ikdr may be a characteristic feature of fusion‐component SC and that it may be involved in the fusion process for the following resons: (1) after the transfer in differentiating medium, cultures of SC in which the expression of Ikdr was previously promoted by exposure to SFM were found to fuse immediately, without the initial 24 h lag time observed in control sister cultures; (2) in the latter “naive” SC, Ikdr was expressed during the first day in differentiating medium, before SC began to fuse; (3) most of the SC that did not fuse even after weeks of exposure to differentiating medium did not express Ikdr; (4) TEA, at a concentration of 3 mM, reduces the amplitude of Ikdr by 55% and the fusion index by 55–67%. © 1995 Wiley‐Liss, Inc.
EGF receptor‐mediated signals are differentially modulated by concanavalin A
Authors: Hazan Rachel , Krushel Leslie , Crossin Kathryn L. 
Published: February 2005

AbstractNIH 3T3 cells expressing hgh levels of the human epidermal growth factor (EGF) receptor were used to examine the effects of the lectin concanavalin A (Con A) on EGF‐mediated signaling events. Proliferation of NIH 3T3 cells expressing high levels of the human EGF receptor was inhibited in a dose‐dependent manner by Con A. At the same time, Con A also inhibited both dimerization and tyrosine phosphorylation of the EGF receptor. Tyrosine phosphorylation of the enzyme phospholiphase C‐γ, a substrate of the phosphorylated EGF receptor kinase, was also inhibited. In contrast, EGF‐stimulated changes in pH, calcium, and levels of inositol phosphates were unaffected by the presence of Con A. These results indicate that certain signals (changes in the levels of intracellular calcium, pH, and inositol phosphates) mediated by EGF binding to its receptor still occur when receptor dimerization and phosphorylation are dramatically decreased, suggesting that multiple independent signals are transmitted by the binding of EGF to its receptor. © 1995 Wiley‐Liss, Inc.