bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression and function of gingival fibroblast C1q receptors are upregulated by interleukin‐1β and transforming growth factor‐β
Authors: Luddington Stephen , Qwarnström E. E. , Page R. C. , Bordin S. 
Published: February 2005

AbstractIn injury and inflammation, complement (C) component C1q, in addition to its central role in initiation of classical pathway of complement activation, modulates diverse cellular functions by binding to specific cell surface receptors. Interaction of substrate‐bound C1q with receptors for the collagen‐like domain of C1q (C1qRC) of human gingival fibroblasts (HGF) promotes cell attachment. We investigated modulation of the adhesive function and expression of C1qRC by interleukin‐1β (IL‐1β) and transforming growth factor‐β (TGF‐β). Confluent fibroblast monolayers were incubated under standard culture conditions with or without cytokines. C1qRC function was measured by attachment assays. IL‐1β and TGF‐β increased fibroblast adhesion to C1q to 146% and 131% of controls, respectively. Cytokine enhancement of HGF adhesion was concentration‐dependent, saturable (20 ng/ml IL‐1β; 1 ng/ml TGF‐β) and time‐dependent (IL‐1β 12‐hr peak; TGF‐β 24‐hr peak). Effect of IL‐1β and TGF‐β on C1qRC expression was assessed by flow cytometry measurements of fluorescence intensity of cells stained with C1q and FITC anti‐C1q antibody, and by binding studies with 125l‐C1q. Cells treated with cytokines displayed a two‐ to four‐fold increased fluorescence of cell‐bound C1q compared to controls. Binding studies indicated the increased fluorescence correlated with increase in number of C1qRC in both IL‐1β (4.7 × 106/cell) and TGF‐β (3.9 × 106/cell)‐treated cells, compared to control (3.0 × 106/cell), but had no effect on binding affinity. Rates of internalization of receptor‐bound C1q were similar in cytokine‐treated cells and controls. We propose from these data that IL‐1β and TGF‐β have the ability to upregulate C1qRC expression, and this effect contributes to increased adhesion of HGF to substrate‐bound C1q. © 1993 Wiley‐Liss, Inc.
Cell cycle dependent regulation of cdc2 mRNA in mouse fibroblasts: Requirement of protein synthesis and of continued mitogenic stimulation
Authors: Buquet‐Fagot Christine , Fagot Dominique , Mester Jan 
Published: February 2005

AbstractIn the chemically transformed mouse fibroblasts (BP‐A31) placed in a serum‐free medium, the cdc2 mRNA content decreases in parallel with the cessation of [3H]thymidine incorporation. Extinction of the cdc2 gene expression is also observed in BP‐A31 cells overexpressing the human c‐myc oncogene. At quies‐cence, the cdc2 gene expression can be reinduced with serum or with other mitogens such as insulin or 12‐O‐tetradecanoyl phorbol 13‐acetate (TPA). The kinetics of induction is characterized by a lag period which differs according to the mitogen used and reflects the length of the G1 phase (4–6 h with insulin or serum, 9–12 h with TPA). The cdc2 mRNA accumulation is prevented when protein synthesis is blocked with cycloheximide, also if the drug is added at a time when the synthesis of cdc2 mRNA is already under way. Similarly, removal of the mitogen leads to a cessation of the cdc2 mRNA accumulation. These results suggest that the increased expression of the cdc2 gene is mediated by (a) short‐lived, growth factor‐regulated protein(s). © 1993 Wiley‐Liss, Inc.
Stretch and anesthetic dependency of atrial natriuretic peptide release demonstrated by an ultrastructural assay
Authors: Newman T. M. , Severs N. J. 
Published: February 2005

AbstractUsing an ultrastructural assay developed to quantify the secretion of atrial natriuretic peptide‐containing granules, release of the hormone, in response to different degrees of atrial distension, is directly demonstrated at the cellular level. The ultrastructural assay developed uses an in situ tannic acid perfusion technique to arrest the exocytosis of atrial granules in the anesthetized rat. Secretory granules, which retain the capacity to undergo exocytosis throughout a 30‐minute tannic acid perfusion, accumulate at the cell surface in a state of fusion with the plasma membrane, with the core contents retained. Quantification of arrested granules thus provides a measure of the rate of granule release and allows the responses to different stimuli to be assessed. By altering the height of the perfusate, perfusion pressure and hence the degree of distension of the right atrium can be increased, and this causes a proportional rise in the release of secretory granules from individual myocytes. An anesthetic regime incorporating fentanyl citrate was found to increase significantly the rate of granule release, and this was further augmented by atrial distension. Quantification of the numbers of cytoplasmic granules under the same conditions did not reveal a reduction in granules. This is thought to be because only a small pool of granules is recruited for exocytosis, and granule production may continue during the perfusion period. Our assay of atrial secretory granule release allows the effect of a variety of stimulatory and inhibitory agents to be assessed directly at the cellular level and provides an independent comparison with previous biochemical data from whole animal and isolated organ studies. © 1993 Wiley‐Liss, Inc.
Characterization of prostaglandin F2α receptor of mouse 3T3 fibroblasts and its functional expression in Xenopus laevis oocytes
Authors: Nakao Akihide , Watanabe Tsuyoshi , Taniguchi Shigeo , Nakamura Motonao , Honda Zen‐Ichiro , Shimizu Takao , Kurokawa Kiyoshi 
Published: February 2005

AbstractProstaglandin (PG) F2α increased [3H]thymidine incorporation into quiescent NIH 3T3 cells, stimulated phosphoinositide breakdown, and raised intracellular Ca2+ concentration ([Ca2+]i) in a dose‐dependent manner with ED50 values of 2.0 × 10−8 M, 4.6 × 10−8 M, and 7.5 × 10−8 M, respectively. The increase in [3H]thymidine incorporation with PGF2α was additive with that seen with epidermal growth factor (EGF) or insulin. The peak [Ca2+]i increase with PGF2α was still obvious in the absence of extracellular Ca2+ and was insensitive to islet activating protein (IAP) pretreatment. Membranes prepared from NIH 3T3 cells exhibited a specific binding for PGF2α, which was sensitive to GTPγS but not sensitive to IAP pretreatment. Xenopus laevis oocytes injected with NIH 3T3 cell mRNA between 18S and 28S rRNA fractionated by sucrose gradient, expressed a PGF2α‐specific Cl− current when examined by voltage clamp. This Cl− current was also insensitive to IAP pretreatment and not affected by extracellular Ca2+ concentration ([Ca2+]o). These results indicate 1) that the NIH 3T3 cells expressed a specific PGF2α receptor which is linked to phosphoinositide‐specific phospholipase C (PLC) activation and to mobilization of Ca2+ via an IAP‐insensitive G‐proteins(s), 2) that this PGF2α receptor may play an active role in the proliferation of NIH 3T3 cells, and 3) that this PGF2α receptor can be expressed in the oocyte system. © 1993 Wiley‐Liss, Inc.
Protein kinase inhibitor, staurosporine, induces a mature neuronal phenotype in SH‐SY5Y human neuroblastoma cells through an α‐, β‐, and ζ‐protein kinase C‐independent pathway
Authors: Jalava Annika , Åkerman Karl , Heikkilä Jari 
Published: February 2005

AbstractPrevious studies have shown that the tumour‐promoting phorbol ester 12‐O‐tetradecanoyl phorbol‐13 acetate (TPA) induces both morphological and functional differentiation in SH‐SY5Y human neuroblastoma cells (Påhlman et al., 1981). In order to investigate the role of protein kinase C (PKC) in TPA‐induced maturation of SH‐SY5Y cells, we have used staurosporine, which is a potent inhibitor of protein kinases including PKC. Treatment of SH‐SY5Y cells with 25 nM staurosporine for 72 hours caused an appearance of long, neuritelike processes with varicosities, terminated by growth cones. The morphological differentiation was accompanied by a cessation of DNA synthesis, induction of growth associated protein 43 (GAP‐43), and neuropeptide Y (NPY) mRNA. These effects of staurosporine were comparable to those elicited by TPA. Staurosporine further induced a time‐dependent increase in the expression of tyrosine hydroxylase protein and a 30‐fold increase in the concentration of noradrenaline. TPA only induced a margginal increase in tyrosine hydroxylase expression. Both TPA and staurosporine induced an appearance of voltage‐gated Ca2+ channels in SH‐SY5Y cells detected with single‐cell fluorescent measurements using fura‐2. The Ca2+ channels were found almost exclusively in growth cones and varicosities. Staurosporine inhibited both basal and a TPA‐induced phosphorylation of an endogenous 80kDa PKC substrate (p80), and also blocked c‐fos proto‐oncogene mRNA expression induced by the phorbol ester. Bryostatin 1, a potent activator of PKC, has failed to induce morphological or functional differentiation in SH‐SY5Y cells (Jalava et al., 1990). Incubation of SH‐SY5Y cells in the presence of 100 nM bryostatin 1 for 24 hours caused a complete disappearance of all immunoreactive α‐, β‐, and ζ‐PKC. The level of ϵ‐PKC decreased by 70%. Staurosporine induced a partial translocation of the ϵ‐isoenzyme but it failed to cause down‐regulation of ϵ‐PKC. Bryostatin 1‐treatment did not interfere in the ability of staurosporine to induce morphological differentiation, cessation of DNA synthesis, and GAP‐43 and NPY mRNA expression. The ability of staurosporine to stimulate tyrosine hydroxylase expression and to increase cellular content of noradrenaline was also unaffected. Taken together the results of this study show that staurosporine induces a mature neuronal noradrenergic phenotype in SH‐SY5Y cells through an α‐, β‐, and ζ‐PKC‐independent pathway. © 1993 Wiley‐Liss, Inc.
Fibroblast contraction of collagen gels requires activation of protein kinase C
Authors: Guidry Clyde 
Published: February 2005

AbstractFibroblasts stimulated to contract collagen gels with serum were completely inhibited by staurosporine, a broad spectrum kinase inhibitor. Further analysis demonstrated that staurosporine is potent (IC50 17 nM), rapid in onset, and completely reversible. Complete inhibition of gel contraction was also observed with calphostin C (IC50 48 nM), an inhibitor specific for protein kinase C (PKC). Similar effects were not observed with KT5926 or KT5720, inhibitors for myosin light chain kinase and cAMP‐dependent kinase, respectively. These data suggested that serum‐stimulated fibroblast contraction is dependent upon activation of PKC. This was also observed with fibroblast contraction stimulated with endothelin‐1, platelet‐derived growth factor, and transforming growth factor beta. PKC activated directly with low concentrations of phorbol ester was observed to stimulate fibroblast contraction of collagen gels, in some cases within 30 minutes of exposure. © 1993 Wiley‐Liss, Inc.
Pericyte growth and contractile phenotype: Modulation by endothelial‐synthesized matrix and comparison with aortic smooth muscle
Authors: Newcomb Patricia M. , Herman Ira M. 
Published: February 2005

AbstractWe compared the effects of endothelial‐synthesized matrix and purified matrix molecules on pericyte (PC) and aortic smooth muscle cell (SMC) growth, heparin sensitivity, and contractile phenotype in vitro. When PC are plated on endothelial‐synthesized (EC) matrix, cell number is, on average, 3.1‐fold higher than identical populations grown on plastic. Under the same conditions, SMC proliferation is stimulated 1.6‐fold. Purified matrix molecules, such as collagen type IV (COLL) or fibronectin (FN), both major components of the EC matrix, stimulate PC/SMC growth 1.2–1.7‐fold. Heparin (100 μg/ml), which inhibits the growth of early passage SMC by 60%, inhibits PC growth ∼50%, when cells were plated on plastic. However, PC plated on EC matrix in the presence of heparin (100 μg/ml) grow as well as parallel cultures grown on plastic (in the absence of heparin). Concomitant with matrix‐stimulated proliferation, we observed a marked reduction in PC containing alpha vascular smooth muscle actin (αVSMA), as seen by immunofluorescence using affinity‐purified antibodies (173/615 positive pericytes on DOC matrix (28%) vs. 221/285 (77%) positive on glass). SMC respond similarly. Whereas αVSMA protein is markedly altered when PC and SMC are cultured on EC matrix, similar reductions in mRNA are not observed. However, Northern blotting does reveal that PC contain 17–30 times the steady‐state levels of αVSMA mRNA compared to SMC. When SMC and PC cultures on plastic are treated with heparin, the steady‐state levels of vascular smooth muscle actin mRNA increase 5 and 1.5 fold, respectively. Similarly, heparin treatment of PC grown on plastic induces a 1.8 fold increase in nonmuscle actin mRNA. These heparin‐induced alterations in isoactin mRNA levels are not seen when PC are cultured on EC matrix. We also observed reductions in αVSMA and β actin mRNA levels when PC are plated on FN, where they maintain a ratio of 13:1 (α:β). Similar ratios are found in SMC present in rat and bovine aortae in vivo. These steady‐state isoactin mRNA ratios are slightly different from those seen in cultured PC (8–10:1; α:β). These results suggest that selective synthesis and remodelling of the endothelial basal lamina may signal alterations in pericyte growth and contractile phenotype during normal vascular morphogenesis, angiogenesis, or during the microvascular remodelling that accompanies hypertensive onset. © 1993 Wiley‐Liss, Inc.
Effect of phospholipid acyl chain modulation on vitamin E incorporation into pulmonary artery endothelial cell membranes
Authors: Patel Jawaharlal M. , Abeles Alan J. , Block Edward R. 
Published: February 2005

AbstractIncorporation of vitamin E (α‐tocopherol) was measured in total membranes of pulmonary artery endothelial cells (PAEC) following treatment with eight synthetic phosphatidylethanolamines (PE) (Palmitoyloleoyl, 16:0–18:1 PE1; distearoyl, 18:0–18:0 PE2; dioleoyl, 18:1–18:1 PE3; stearoyl‐ linoleoyl, 18:0–18:2 PE4; dilinoleoyl, 18:2–18:2 PE5; stearoyl‐arachiod‐nyl, 18:0–20:4 PE6; diarachidonyl, 20:4–20:4 PE7; and stearoyl‐docosahexenoyl, 18:0–22:6 PE8). Endogenous PE content of native membranes was 0.88 ± 0.01 nmol/mg protein. Incorporation of PE irrespective of fatty acid content significantly (P < 0.02) increased the PE content of total membranes. Vitamin E incorporation in control membranes was 63 ± 9 nmol/mg protein. Incorporations of vitamin E in PE1‐ to PE7‐treated cells were significantly (P < 0.05) increased compared to controls and were comparable to each other. Vitamin E incorporation into PE8‐treated cells was threefold greater (P < 0.001) thatn controls and twofold greater (P < 0.001) than PE1‐ to PE7‐treated cells. Increased PE content results in increased vitamin E incorporation into PAEC membranes irrespective of the fatty acids present on the acyl chain, and maximal incorporation of vitamin E in PE8‐treated cells may relate to the increased carbon chain length rather than to the degree of unsaturation at the sn2 position. © 1993 Wiley‐Liss, Inc.
Deficiencies in collagen phagocytosis by human fibroblasts in vitro: A mechanism for fibrosis?
Authors: McCulloch Christopher A. G. , Knowles Gisele C. 
Published: February 2005

AbstractDegradation of collagen by fibroblast phagocytosis is an important pathway for physiological remodelling of soft connective tissues. Perturbations of this pathway may provide a mechanism for the development of fibrotic lesions. As collagen phagocytosis may be regulated by either a change of the proportions or the activity of phagocytic cells, we quantified phagocytosis with an in vitro model system. Collagen‐coated fluorescent latex beads were incubated with human gingival fibroblasts and the fluorescence associated with internalized beads was measured by flow cytometry. Cells from normal tissues that had been incubated with beads for 3 hours contained a mean of 64% phagocytic cells; however, a small subpopulation (10% of phagocytic cells) contained more than threefold higher numbers of beads per cell than the mean. In contrast, cells from fibrotic lesions exhibited a large reduction of the proportions of phagocytic cells (mean = 13.8%) and there were no cells with high numbers of beads. On the basis of 3H‐Tdr labeling, cells from fibrotic lesions that had internalized beads failed to proliferate, in contrast to phagocytic cells from normal tissues, which underwent repeated cell divisions. This result was not due to variations of cell cycle phase as there was no preferential internalization of beads during different phases of the cell cycle. The low phagocytic rate of cells from fibrotic lesions was also not due to asymmetric partitioning of phagosomes at mitosis as videocinemicrography of bead‐labeled phagosomes in single, pre‐mitotic cells demonstrated that > 90% of phagocytic cells equally partitioned beads to daughter cells. To investigate if inhibition of phagocytosis could be replicated in vitro, cells were incubated with the fibrosis‐inducing drugs nifedipine or dilantin. These cultures exhibited marked (15–75%), dose‐dependent reductions in the proportions of phagocytic cells, but there was no reduction in bead number per cell. Fibrotic lesions appear to contain fibroblasts with marked deficiencies in phagocytosis and the reduced phagocytic activity of these cells may contribute to unbalanced degradation and fibrosis. © 1993 Wiley‐Liss, Inc.
Myocyte DNA synthesis with aging: Correlation with ventricular loading in rats
Authors: Capasso Joseph M. , Bruno Silvia , Li Peng , Zhang Xun , Darzynkiewicz Zbigniew , Anversa Piero 
Published: February 2005

AbstractTo determine whether the detrimental mechanical and anatomical changes that occur biventricularly with aging are associated with activation of DNA synthesis, flow cytometric analysis was performed on myocyte nuclei prepared from the left and right ventricles of rats at 4, 12, 20, and 29 months of age. Heart weight increased significantly with age, and this growth adaptation was associated with the development of left ventricular failure and right ventricular dysfunction. These phenomena were coupled with marked elevations in diastolic wall stress and increases in the percentage of myocyte nuclei in S+G2M in both ventricles. Linear regression analyses revealed a direct correlation between the fraction of myocytes that entered the cell cycle and diastolic pressure and wall stress. An inverse relation was found between the percentage of myocyte nuclei in S+G2M and +dP/dt and systolic wall stress. Thus the depression of hemodynamic performance coupled with alterations in the loading conditions contributes, at least in part, to increased DNA synthesis in cardiac myocytes with age. © 1993 Wiley‐Liss, Inc.
Oleic acid supplementation reduces oxidant‐mediated dysfunction of cultured porcine pulmonary artery endothelial cells
Authors: Hart C. Michael , Andreoli Sharon P. , Patterson Carolyn E. , Garcia Joe G. N. 
Published: February 2005

AbstractWe have previously shown that supplementing cultured porcine pulmonary artery endothelial cells (PAEC) with exogenous oleic acid (18:1ω9) alters the fatty acid composition of the cells and reduces oxidant‐mediated cytotoxicity. Because the mechanisms by which lipid alterations modulate oxidant susceptibility have not been defined, the ability of 18:1 to reduce hydrogen peroxide (H2O2)‐mediated PAEC dysfunction was evaluated. PAEC monolayers on polycarbonate filters were incubated for 3 h in maintenance medium supplemented with either 0.1 mM 18.1 in ethanol vehicle (ETOH) or with an equivalent volume of vehicle alone. Twenty‐four hours later monolayers were treated for 30 min with 50 or 100 μM H2O2 in Hanks' balanced salt solution (HBSS) or with HBSS alone (nonoxidant control). As a functional index of PAEC monolayer integrity, the permeability of monolayers to albumin was then measured for 3 h. Treatment with 100 μM H2O2 caused cytotoxicity and progressive increases in PAEC monolayer permeability that were attenuated by 18:1 supplementation, whereas 50 μM H2O2 caused only a transient increase in permeability without cytotoxicity. Supplementation with 18:1 also attenuated H2O2‐induced reductions in PAEC adenosine triphosphate (ATP) content and disruption of PAEC microfilament architecture. The ATP content of PAEC monolayers was reversibly reduced in the absence of oxidant stress by incubation with glucose‐depleted medium containing deoxyglucose and antimycin A. Metabolic inhibitor‐induced ATP depletion increased monolayer permeability and altered cytoskeletal architecture, alterations that resolved during recovery of PAEC ATP content. These results demonstrate that ATP depletion plays a critical role in barrier dysfunction and suggests that the ability of 18:1 to reduce oxidant‐mediated PAEC dysfunction and injury may relate directly to its ability to preserve PAEC ATP content. © 1993 Wiley‐Liss, Inc.
Regulation of RNA degradation in cultured rat hepatocytes: Effects of specific amino acids and insulin
Authors: Balavoine Sophie , Feldmann Gérard , Lardeux Bernard 
Published: February 2005

AbstractThe regulation of RNA degradation by specific amino acids and insulin was investigated in cultured rat hepatocytes from fed rats previously injected in vivo with [6‐14C]orotic acid. The effects of three groups of amino acids were compared to those of a complete amino acid mixture. The first one consisted of the eight amino acids (leucine, proline, glutamine, histidine, phenylalanine, tyrosine, methionine, tryptophan) previously found to be particularly effective in the control of proteolysis. The two other groups were defined from our study with single additions of amino acids, one consisting of proline, asparagine, glutamine, alanine, phenylalanine, and leucine and the other including the latter group with serine, histidine, and tyrosine. The results showed that these three groups were able to strongly inhibit deprivation‐induced RNA breakdown at one and ten times normal plasma concentrations but to a lower extent than the complete amino acid mixture. Six amino acids (proline, asparagine, glutamine, alanine, phenylalanine, leucine) inhibited individually RNA degradation by more than 20%. However, the deletions of proline, asparagine, glutamine, or alanine from the group of these six amino acids were not followed by a loss of inhibitory effect. On the contrary, an important loss of inhibition was observed when leucine and phenylalanine were deleted. Furthermore, only these two amino acids exhibited an additive inhibitory effect. Thus leucine and phenylalanine could be considered as important inhibitors of RNA breakdown in cultured rat hepatocytes. Finally, insulin which had no significant effect on RNA degradation in the absence of amino acids, was able to potentiate the inhibitory effect of different amino acid groups. © 1993 Wiley‐Liss, Inc.