bluuebunny/crossref_metadata_2025_split huggingface dataset:
Basic fibroblast growth factor and transforming growth factor beta‐1: Synergistic mediators of angiogenesis in vitro
Authors: Gajdusek Corinne M. , Luo Zhengyu , Mayberg Marc R. 
Published: February 2005

AbstractWe investigated the relative roles of basic fibroblast growth factor (bFGF) and transforming growth factor beta‐1 (TGF‐b) on bovine aortic endothelial cell mitogenesis and morphogenesis using two‐dimensional Petri dish cultures and a threedimensional hydrated collagen gel. bFGF alone stimulated endothelial cell proliferation with an EC50 of 0.5 ng/ml. At bFGF levels greater than 2.5 ng/ml, morphologic alterations in confluent monolayers predominated; cells changed from a cobblestone morphology to an elongated cell pattern and showed enhanced migration into a denuded area of a Petri dish. In the three‐dimensional model, exposure of endothelial cell monolayers to high bFGF levels stimulated minor cell migration directly under the monolayer but no invasion into the gel matrix. In combination with bFGF, heparin potentiated morphogenic changes, but not mitogenesis. bFGF, modification of the antiproliferative effect of TGF‐b in confluent cultures was evidenced by induction of endothelial cell sprouting in response to 0.5 ng/ml TGF‐b and 10–20 ng/ml bFGF in two‐dimensional cultures. On collagen gels, endothelial cells migrated into the deep layers of the gel in a dose‐dependent manner: invasion was maximal at 0.3–0.7 ng/ml TGF‐b with decreased invasion at higher concentrations. The optimal collagen concentration that supported cell invasion was 0.075% collagen with the number of invading cells decreasing with increasing collagen gel density. By scanning electron microscopy, invading endothelial cells assumed a fibroblast‐like appearance with slender cell extensions. We concluded that bFGF and TGF‐b had independent effects on endothelial cell morphology and mitogenesis in culture. In combination at specific doses, these agents stimulated sprouting in the two‐dimensional model and cell invasion in a collagen gel model. Morphogenic changes may be the primary event in determining angiogenesis. © 1993 Wiley‐Liss, Inc.
Effect of glutamine on heat‐shock‐induced mRNA and stress proteins
Authors: Nissim Itzhak , States Beatrice , Hardy Mattie , Pleasure Jeanette , Nissim Ilana 
Published: February 2005

AbstractOur aim was to delineate the effect of glutamine on the level of heat shockinducible mRNA and synthesis of stress protein(s) in cultured kidney cells. Experiments were carried out using opossum kidney (OK) cells. The induction of HSP70 mRNA as well as the synthesis of 72,73 kDa stress proteins was evaluated in cell monolayers exposed to 45°C for 15 minutes followed by a recovery period at 37°C for 3 hours. Incubations were performed in Krebs buffer supplemented with 0, 2, 5, or 10 mM glutamine. A separate series of experiments was performed in the presence of glutamine metabolites, such as NH4CI, glutamate, or aspartate. Glutamine without preincubation at 37°C remarkably increased the steady‐state level of HSP70 mRNA as well as the production of 72,73 kDa stress proteins in a dose‐dependent manner. The production of stress protein(s) in the presence of glutamine was associated with decreased percent LDH efflux, suggesting cytoprotective action of glutamine in cultured kidney cells. However, when OK cells were preincubated for 1 hour at 37°C with 10 mM glutamine, there was an approximately fourfold decline in level of HSP70 mRNA compared with experiments in the presence of 10 mM glutamine without preincubation. In addition, metabolites of glutamine, i.e., ammonia and glutamate decreased the level of heat‐inducible HSP70 mRNA. Furthermore, aspartate or NH4CI had little effect on LDH release compared with heat shock experiments, without addition of amino acids. These observations suggest that metabolites of glutamine may blunt the steady‐state level of glutamate or HSP70 mRNA. The decreased level of HSP70 mRNA in the presence of NH4CI may explain the role of ammonia in renal injury and brain toxicity, as well as glutamate excitotoxicity. © 1993 Wiley‐Liss, Inc.
Tissue inhibitor of metalloproteinases‐2 inhibits bFGF‐induced human microvascular endothelial cell proliferation
Authors: Murphy Anne N. , Unsworth Edward J. , Stetler‐Stevenson William G. 
Published: February 2005

AbstractTissue inhibitor of metalloproteinase‐2 (TIMP‐2), a protease inhibitor that binds to the latent and active forms of 72 kDa type IV collagenase (gelatinase A), was found to inhibit the in vitro proliferation of human microvascular endothelial (HME) cells stimulated with bFGF and 5% serum. The maximal inhibitory effect of TIMP‐2 on incorporation of 3H‐thymidine was evident 24 hours after bFGF stimulation of these cells and ranged between 45 and 60%. The half‐maximal effective concentration of TIMP‐2 was 107 ± 12 nM (S.D.). In contrast, TIMP‐1 was not found to slow the growth of HME cells. The inhibition of cell proliferation observed with TIMP‐2 was not mimicked by addition to the culture medium of BB94, a general matrix metalloproteinase inhibitor, nor antibodies to the 72 kDa type IV collagenase. In addition to growth, two other cell functions associated with the angiogenic process were tested for sensitivity to TIMP‐2. Cell adhesion to tissue culture platic was slightly stimulated by TIMP‐2, and cell migration was inhibited with short‐term exposure to TIMP‐2, but neither process was affected by longer‐term exposure. The ability of TIMP‐2 to inhibit cultured endothelial cell proliferation independent of protease inhibitory activity suggests that TIMP‐2 may have additional actions which may limit neovascularization associated with solid tumor growth and metastasis in vivo. © 1993 Wiley‐Liss, Inc.
Differential expression of P‐glycoprotein genes in primary rat hepatocyte culture
Authors: Lee Chow Hwee , Bradley Grace , Zhang Jian‐Ting , Ling Victor 
Published: February 2005

AbstractThe multidrug resistance (MDR)–associated protein, P‐glycoprotein (Pgp), is expressed on the bile canalicular surface of hepatocytes, where it is thought to function in the detoxification of xenobiotics or in the transport of specific metabolites. Several studies have shown that Pgp expression in rat liver can be perturbed in vivo and in vitro; however, it is not known which of the 3 Pgp genes (class I, II, or III) are involved. In rodents, the class I and II Pgp genes have been shown to mediate MDR while the class III gene apparently does not. In this eport, we have used gene‐specific probes generated from the 3′‐untranslated regions of the three rat Pgp genes (Deuchars et al.: Biochim. Biophys. Acta, 1130:157–165, 1992) to investigate Pgp gene expression in primary rat hepatocytes. We observed that the class II Pgp mRNA, the least abundant in the intact liver, is dramatically increased in culture over a 48 h period, while the class I Pgp showed only a modest increase in mRNA level. In contrast, the class III Pgp mRNA, which is the most abundant in the intact liver, exhibited a gradual decline. In rat liver hepatocytes, different culture conditions, as well as drugs such as cytochalasin D and colchicine, appear to affect the level of the class II Pgp gene expression. Moreover, under all these conditions, there is a strong correlation between the level of the class II Pgp and cytoskeletal (actin and tubulin) mRNAs. Thus, there may be a common mechanism regulating the expression of cytoskeletal protein genes and the class II Pgp gene. These findings have implications for our understanding of the regulation of Pgp gene expression in normal and malignant tissues. © 1993 Wiley‐Liss, Inc.
Membrane‐anchored proteoglycans of mouse macrophages: P388D1 cells express a syndecan‐4–like heparan sulfate proteoglycan and a distinct chondroitin sulfate form
Authors: Yeaman Charles , Rapraeger Alan C. 
Published: February 2005

AbstractProteoglycan accumulation by thioglycollate‐elicited mouse peritoneal macrophages and a panel of murine monocyte‐macrophage cell lines has been examined to determine whether these cells express plasma membrane‐anchored heparan sulfate proteoglycans. Initially, cells were screened for heparan sulfate and chondroitin sulfate glycosaminoglycans after metabolic labeling with radiosulfate. Chondroitin sulfate is secreted to a variable extent by every cell type examined. In contrast, heparan sulfate is all but absent from immature pre‐monocytes and is associated predominantly with the cell layer of mature macrophage‐like cells. In the P388D1 cell line, the cell‐associated chondroitin sulfate is largely present as a plasma membrane‐anchored proteoglycan containing a 55 kD core protein moiety, which appears to be unique. In contrast, the cell‐associated heparan sulfate is composed of a proteoglycan fraction and protein‐free glycosaminoglycan chains, which accumulate intracellularly. A fraction of the heparan sulfate proteoglycan contains a lipophilic domain and can be released from cells following mild treatment with trypsin, suggesting that it is anchored in the plasma membrane. Isolation of this proteoglycan indicates that it is likely syndecan‐4: it is expressed as a heparan sulfate proteoglycan at the cell surface, it is cleaved from the plasma membrane by low concentrations of trypsin, and it consists of a single 37 kD core protein moiety that co‐migrates with syndecan‐4 isolated from NMuMG mouse mammary epithelial cells. Northern analysis reveals that a panel of macrophage‐like cell lines accumulate similar amounts of syndecan‐4 mRNA, demonstrating that this proteoglycan is expressed by a variety of mature macrophage‐like cells. Syndecan‐1 mRNA is present only in a subset of these cells, suggesting that the expression of this heparan sulfate proteoglycan may be more highly regulated by these cells. © 1993 Wiley‐Liss, Inc.
Long‐term effects of tumor necrosis factor on LLC‐PK1 transepithelial resistance
Authors: Marano C. W. , Laughlin K. V. , Russo L. M. , Soler A. Peralta , Mullin J. M. 
Published: February 2005

AbstractRenal epitheliaL LLC‐PK1 cell sheets incubated with tumor necrosis factor (TNF) undergo an acute, spontaneous, and rapidly reversible decrease in transepithelial resistance (TER). (Mullin et al., 1992). However, 24 to 72 h following TNF exposure, TER across the cell sheet increases 2‐fold. This later effect of TNF is also reversible, albeit slowly. The TER of TNF‐treated cell sheets then declines toward initia levels between 72 and 144 h following exposure to the cytokine. Whereas the long‐term increase in TER following TNF exposure is not associated with a decreased transepithelial 14C‐mannitol flux (size selectivity), the charge (anionic) selectivity of the LLC‐PK1 tight junction is decreased. Basal‐lateral (ouabain and bumetanide‐insensitive) Rb+ and apical Na+‐dependent alpha‐methylglucoside (AMG) uptake into the cell are both reduced in cultures exposed to TNF 24 h earlier. Correspondingly, this long‐term effect on TER is accompanied by a 30% decrease in short circuit current(iSCC). Along with an observed increase in basallateral methylamino‐isobutyric acid (MeAIB) influx into the cells, an increased incorporation of [3H]‐thymidine into DNA indicates increased cell cycling after exposure to TNF. While the increase in cell cycling is not sustained for the duration of the elevation in TER, it does appear to initiate a sequence of events that lead to the sustained increase in TER. A decrease in the lateral intercellular space, observed between these epithelial cells after long‐term TNF exposure, may be a mechanism for the elevated TER following from the mitogenesis and/or transport changes. This overall long‐term tightening of an epithelium in response to TNF may function, in part, as a compensatory action of the epithelium to reestablish its effectiveness as a physiological barrier, following the acute effect of TNF. © 1993 Wiley‐Liss, Inc.
Organization of calsequestrin‐positive sarcoplasmic reticulum in rat cardiomyocytes in culture
Authors: Ioshii Sérgio O. , Imanaka‐Yoshida Kyoko , Yoshida Toshimichi 
Published: February 2005

AbstractThe sarcoplasmic reticulum (SR) regulates the levels of cytoplasmic free Ca2+ ions in muscle cells. Calsequestrin is a major Ca2+ ‐storing protein and is localized at special sites in the SR. To investigate the development of calsequestrin‐positive SR and its interaction with the cytoskeleton, we examined the distribution of calsequestrin in cultured cardiomyocytes from newborn rats by immunofluorescence with anticalsequestrin and antitubulin antibodies and rhodamine‐phalloidin. In frozen sections of neonatal rat heart, anticalsequestrin immunostaining was apparent as cross‐striations at Z‐lines. When newborn cardiomyocytes were isolated, calsequestrin‐positive SR was disorganized and was apparent as small vesicles beneath the sarcolemma, whereas myofibrils accumulated in the center of the cells. As the cells spread in culture, calsequestrin‐positive vesicles spread to the periphery of the cytoplasm, becoming associated with the developing myofibrils. In mature cells, calsequestrin was closely associated with myofibrils, showing cross‐striations at the Z‐lines. Double‐labeling using anticalsequestrin and antitubulin antibodies demonstrated that the distribution of calsequestrin‐positive structures was similar to that of the microtubular arrays. When the microtubules were depolymerized by nocodazole at an early stage, the extension of the SR to the cell periphery was inhibited. In mature cardiomyocytes, nocodazole appeared not to affect the distribution of the SR. These results indicate that the calsequestrin‐positive SR in cardiomyocytes is organized at the proper sites of myofibrils during myofibrillogenesis and that the microtubules might serve as tracts for the transport of components of the SR. © 1994 Wiley‐Liss, Inc.
TGF‐β1 induces the expression of type I collagen and SPARC, and enhances contraction of collagen gels, by fibroblasts from young and aged donors
Authors: Reed May J. , Vernon Robert B. , Abrass Itamar B. , Sage E. Helene 
Published: February 2005

AbstractFibroblasts have a major role in the synthesis and reorganization of extracellular matrix that occur during wound repair. An impaired biosynthetic or functional response of these cells to stimulation by growth factors might contribute to the delayed wound healing noted in aging. We, therefore, compared the responses of dermal fibroblasts from young and elderly individuals (26, 29, 65, 89, 90, and 92 years of age) to transforming growth factor‐β1 (TGF‐β1) with respect to: (1) the synthesis of type I collagen and SPARC (two extracellular matrix proteins that are highly expressed by dermal fibroblasts during the remodeling phase of wound repair) and (2) the contraction of collagen gels, an in vitro assay of wound contraction. With the exception of one young donor, all cultures exposed for 44 hours to 10 ng/ml TGF‐β1 exhibited a 1.6‐ to 5.5‐fold increase in the levels of secreted type 1 collagen and SPARC, relative to untreated cultures, and exhibited a 2.0‐ to 6.2‐fold increase in the amounts of the corresponding mRNAs. Moreover, the dose‐response to TGF‐β1 (0.1–10 ng/ml), as determined by synthesis of type I collagen and SPARC mRNA, was as vigorous in cells from aged donors as in cells from a young donor. In assays of collagen gel contraction, fibroblasts from all donors were stimulated to a similar degree by 10 ng/ml TGF‐β1. In conclusion, cells from both young and aged donors exhibited similar biosynthetic and contractile properties with exposure to TGF‐β1. It therefore appears that the impaired wound healing noted in the aged does not result from a failure of their dermal fibroblasts to respond to this cytokine. © 1994 Wiley‐Liss, Inc.
Intracellular dynamics of c‐myc mRNA traffic in single cells in situ
Authors: Pallavicini M. G. , George T. , Deteresa P. S. , Amendola R. , Gray J. W. 
Published: February 2005

AbstractProcessing and intracellular transport of RNA transcripts are essential for gene expression. Translational regulation of gene expression may occur by several mechanisms, including control of transcript movement from sites of synthesis to site(s) of translation. We describe temporal analysis of the intracellular translocation of c‐myc transcripts from the site of synthesis in the nucleus to sites of translation in the cytoplasm. Fluorescence in situ hybridization (FISH) and quantitative fluorescence microscopy were used to measure intracellular traffic of c‐myc transcripts in individual recombinant cells following activation of c‐myc sequences linked to a heat shock promoter. C‐myc nuclear transcripts are visible in the nucleus within minutes of heat exposure. Transcripts remain in the nucleus for at least 4 hr after gene activation. Transport of c‐myc transcripts to the cytoplasm begins ∼ 1 hr after cells are returned to 37°C. These data demonstrate the feasibility of measuring intracellular transcript transport following gene activation and provide a description of the kinetics of intracellular traffic of inducible c‐myc transcripts in heated cells in situ. © 1994 Wiley‐Liss, Inc.
Expression of a growth arrest specific gene (gas‐6) during liver regeneration: Molecular mechanisms and signalling pathways
Authors: Ferrero Marina , Desiderio Maria Alfonsina , Martinotti Alessia , Melani Cecilia , Bernelli‐Zazzera Aldo , Colombo Mario P. , Cairo Gaetano 
Published: February 2005

AbstractA set of growth arrest‐specific (gas) genes negatively regulated by serum has been identified. To define the role of gas genes in a model of cell proliferation in vivo we analyzed the expression of one of these genes (gas‐6) during liver regeneration after partial hepatectomy (PH). We found that gas‐6 mRNA was down‐regulated 4 hours after PH, within the G0 to G1 transition. Later on, gas‐6 mRNA increased over the level found in normal liver with a peak at 16 hours, before the onset of DNA synthesis. This surge was probably triggered by an inflammatory response caused by the surgical trauma, because an increase of similar extent occurring with the same time course was present in livers of sham‐operated and turpentine‐treated rats. Comparison of mRNA steady state levels with nuclear transcription rates indicated that gas‐6 expression is post‐transcriptionally regulated. As we found that down‐regulation of gas‐6 expression was prevented by treatment with Actinomycin D, a labile protein might be involved in the determination of gas‐6 mRNA stability. To investigate the mitogenic signals controlling gas‐6 expression during liver regeneration we treated hepatectomized rats with a specific alpha‐1‐adrenoceptor blocker (prazosin) as well as with drugs which modify intracellular calcium levels. The decrease of gas‐6 mRNA 4 hours after PH was prevented by prazosin and by neomycin, an inhibitor of calcium release from endogenous stores. These findings suggest that down‐regulation of gas‐6 expression during hepatic regeneration is triggered by catecholamines interaction with alpha‐1‐adrenergic receptors and by subsequent calcium release. In addition we found that the rise of gas‐6 gene expression occurring at 16 hours after PH was not affected by prazosin but was inhibited by trifluoperazine. Therefore, we suggest that up‐regulation of gas‐6 gene expression is mediated by the interaction of calcium with calmodulin, independently of catecholamines. © 1994 Wiley‐Liss, Inc.
Stimulatory effect of a phorbol ester on expression of insulin‐like growth factor (IGF) binding protein‐2 and level of IGF‐I receptors in mouse osteoblastic MC3T3‐E1 cells
Authors: Hakeda Yoshiyuki , Yoshizawa Kenji , Hurley Marja , Kawaguchi Hiroshi , Tezuka Ken‐Ichi , Tanaka Kayo , Satoh Takuya , Kumegawa Masayoshi 
Published: February 2005

AbstractWe examined the relationship between signal transduction and the expression of insulin‐like growth factor I (IGF‐I), IGF‐I receptor level, and IGF binding proteins (IGFBPs) in murine clonal osteoblastic MC3T3‐E1 cells. 12–O‐Tetradecanoylphorbol‐13‐acetate (TPA), an activator of protein kinase C, decreased the secretion of immunoreactive IGF‐I into the medium, whereas dibutyryl cAMP (Bt2cAMP) augmented the secretion In contrast, TPA increased the level of type IIGF receptor on the cells. Furthermore, MC3T3‐E1 cells produced and secreted at least three different IGFBPs with molecular masses of 24, 30, and 34 kDa, and the 24‐kDa IGFBP was predominant under normal conditions. However, TPA specifically increased the secretion of the 34‐kDa IGFBP. The N‐terminal amino acid sequence of the purified 34‐kDa IGFBP was nearly identical with that of rat IGFBP‐2. Furthermore, the 34‐kDa IGFBP was immunoreactive to anti‐IGFBP‐2 antiserum. The level of IGFBP‐2 mRNA in the cells was increased by TPA, indicating that the increase in IGFBP‐2 secretion results from the stimulation of IGFBP‐2 production. In contrast, Bt2cAMP affected neither IGF‐l receptor number nor the IGFBP secretion. These results indicate that the production of IGF‐l and the expression of IGF‐l receptors and IGFBP‐2 are up‐regulated by the activation of adenylate cyclase and protein kinase C, respectively, in osteoblastic MC3T3‐E1 cells. © 1994 Willey‐Liss, Inc.
Interaction between cells and elastin fibers: An ultrastructural and immunocytochemical study
Authors: Perdomo Juana J. , Gounon Pierre , Schaeverbeke Madeleine , Schaeverbeke Jean , Groult Vanina , Jacob Marie P. , Robert Ladislas 
Published: February 2005

AbstractMesenchymal cells (fibroblasts, smooth muscle cells) and endothelial cells were shown to interact with elastin fibers. The strong adhesion of elastin fibers to these cells is mediated by a cell membrane complex with a major glycoprotein component of 120 kDa designated as elastonectin. This interaction was studied by transmission electron microscopy (TEM) and immunocytochemical techniques using antibodies raised against the elastin adhesive proteins. When fibroblasts and smooth muscle cells were cultured in presence of elastin fibers, TEM showed an adhesion mechanism that takes place over several sites along the plasma membrane of these cells. Endothelial cells showed a very close association with elastin, emitting “pseudopodia” that embody the fibers. TEM, indirect immunofluorescence, immunoperoxidase, and confocal microscopy showed the presence and localization of cell membrane components synthesized in large quantities when cells were incubated in presence of elastin. Cells without elastin fibers barely revealed the adhesive membrane complex. These results confirm and extend previous findings concerning the presence of an inducible cell membrane complex that mediates the adhesion of elastin fibers to these cell types. © 1994 Wiley‐Liss, Inc.
Effects of cytokines on synthesis and function of the hepatic asialoglycoprotein receptor
Authors: Treichel Ulrich , Paietta Elisabeth , Poralla Thomas , Meyer zum Büschenfelde Karl‐Hermann , Stockert Richard J. 
Published: February 2005

AbstractIn this study we have investigated whether cytokines, critical mediators of the immune response, might have a direct effect on the expression and/or function of the human hepatic asialoglycoprotein receptor (ASGPR). Binding and uptake of asialoglycoproteins by the human hepatoma cell line, HepG2, and by freshly isolated rat hepatocytes were inhibited by 50% after 3–6 hours and completely abolished following a 24 hour exposure to tumor necrosis factor (TNF) α, interferon (INF) α or γ, or interleukin‐2 (IL‐2). The loss of ASGPR binding activity mediated by IL‐2 was reversible up to 4 hours of exposure and accompanied by the selective phosphorylatior, of the cell‐surface receptor. Steady‐state levels of total cellular ASGPR protein remained unchanged over the first 6 hours of IL‐2 incubation but declined in a dose dependent manner thereafter. This down regulation of ASGPR expression was due to reduced synthesis as a result of reduced receptor transcript levels. No loss was detected, however, of cell surface‐associated receptor protein even after 24 hours of IL‐2 incubation, suggesting that cytokine induced phosphorvlation constitutes a mechanism to regulate receptor activity. © 1994 Wiley‐Liss, Inc.