bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential antimitogenic effectiveness of atrial natriuretic peptides in primary versus subcultured rat aortic smooth muscle cells: Relationship to expression of ANF‐C receptors
Authors: Cahill Paul A. , Hassid Aviv 
Published: February 2005

AbstractPrevious studies have shown that atrial natriuretic peptides inhibit mitogenesis in subcultured aortic smooth muscle cells by a mechanism that appears to be mediated via the C‐type or “clearance” receptor. In the current study, we have compared the antimitogenic effect of these peptides in serum‐stimulated primary aortic smooth muscle cell cultures and in subcultured cells. A series of atrial peptides, including rANF99–126, rANF103–126, and rANF103–125, were only poorly antimitogenic in serum‐stimulated primary cultures, whereas des[Cys105, Cys121] rANF104–126 which binds selectively to the ANF‐C receptors had no antimitogenic activity. In contrast, in subcultured cells (between subcultures 3 and 25), rANF99–126, rANF103–126, rANF103–126, Cys116rANF102–116, and des[Cys105, Cys121]rANF104–126 inhibited serum‐induced [3H]thymidine incorporation (IC50 in the range of 10–50 nM), with maximal inhibition of 40–70%. The lack of antimitogenic activity in primary cultures did not appear to be related to the lack of cGMP elevation elicited by atrial peptides or to an inherent insensitivity to the action of antimitogens, because primary cultures were responsive to the cGMP‐elevating effect of atrial peptides and the cells were more rather than less sensitive to the antimitogenic effect of the nitric‐oxide‐vasodilator, SNAP, as compared to subcultured cells. Analysis of the affinity and binding capacity of freshly isolated aortic membranes, and primary or secondary cultures for [125I]rANF99–126, revealed that the number of ANF receptors increased by tenfold, following subculture. Moreover, subcultured cells contained receptors with increased binding affinity for peptide analogues selective for the ANF‐C‐type type receptor. Covalent cross‐linking studies with (125I)rANF99–126 confirmed that membranes prepared from fresh aortae predominantly expressed the ANF‐A/guanylate cyclase receptor, whereas in subcultured cells the predominantly cross‐linked protein was the ANF‐C‐type receptor, with receptors in primary cultures occupying an intermediate position. These results suggest that the binding and antimitogenic activity of atrial peptides in aortic smooth muscle cells depends on the phenotypic state of these cells. Moreover, the increased antimitogenic potency of atrial peptides in secondary cultures may reflect increased expression of the ANF‐C‐type receptors. © 1993 Wiley‐Liss, Inc.
Contrasting effect of transforming growth factor type beta 1 (TGF‐β1) on proliferation and interleukin‐2 receptor expression in activated and rapidly cycling immature (CD3−CD4−CD8−) thymocytes
Authors: d'Angeac Arnaud Dupuy , Rème Thierry , Monier Serge , Gao Qinglin , Duperray Christophe , Jullien Pierre , Dornand Jacques 
Published: February 2005

AbstractTransforming growth factor β (TGF‐β) is a cytokine with immunoregulatory properties that acts negatively on T lymphocyte proliferation. However, with the EL 4–6.1 variant of the murine thymoma EL 4 activated with phorbol ester and/or interleukin‐1 (IL‐1), we recently found that it up‐regulates interleukin‐2‐receptor (IL‐2R) expression. Since EL 4–6.1 cells share phenotypic and functional characteristics with the immature thymic subset lacking CD4 and CD8 accessory molecules (DN), we investigated the effect of TGF‐β1 on the IL‐2R 55kD α chain expression and proliferation of activated DN cells and especially in DN cells that do not express CD3. We observed that TGF‐β1 was able to increase both the percentage of CD3−DN cells expressing IL‐2Rα chains and the expression of IL‐2Rα chain in these cells. This stimulatory effect of TGF‐β1 was distal from early transduction events. In addition, TGF‐β1 was found to modulate CD3−DN cell proliferation. During differentiation in the thymus, CD3−DN cells transiently express the IL‐2Rα chain of the IL‐2R and these IL‐2R+ CD3−DN cells are preprogrammed to down‐regulate the IL‐2Rα chain and up‐regulate the CD4 and CD8 accessory molecule. We thus also tested the effect of TGF‐β1 on IL‐2Rα chain expression in these in vitro differentiating CD3−DN cells. We found that TGF‐β1 neither significantly affected IL‐2R expression nor changed CD4 or CD8 expression. Hence, in CD3−DN cells, the effect of TGF‐β1 on IL‐2R expression seems to be restricted to proliferating cells. © 1993 Wiley‐Liss, Inc.
Role of receptor complexes in resistance or sensitivity to growth inhibition by TGFβ in intestinal epithelial cell clones
Authors: Mulder Kathleen M. , Segarini Patricia R. , Morris Sheila L. , Ziman Jill M. , Choi Ho Gene 
Published: February 2005

AbstractUntransformed rat intestinal epithelial cells (IEC‐18) were chemically mutagenized, selected in the presence of TGFβ1, and cloned by limiting dilution. Two clones (4–5, 4–6) were resistant to growth inhibition by both TGFβ1 and TGFβ2. Another clone (4–1) was more sensitive to both TGFβ isoforms (relative to parental IEC‐18 cells). IC50 values for TGFβ1 and 2 in the 4–1 cells were at least 1/9 those of the parental cells; growth rates were reduced by 49% for TGFβ1 and by 26% for TGFβ2 in this clone. This increased sensitivity to TGFβ was explained by the 5‐ to 10‐fold increase, relative to parental cells, in binding of TGFβ1 and TGFβ2 to both the type I and II receptors. In contrast, the resistance to growth inhibition by TGFβ in the 4–5 and 4–6 cells could not be explained by a decrease in either TGFβ binding affinities or in total number of receptors expressed, by the presence of serum binding components, or by occupation of receptor binding sites with autocrine TGF‐β1. However, in comparison to TGFβ‐sensitive cells (IEC‐18, 4–1), the resistant cells displayed a higher ratio of type II relative to type I receptor binding by TGF‐β1. Thus, a critical ratio of binding to receptor subtypes correlated with growth inhibition by TGF‐β1. Resistance to TGF‐β2 in the same clones did not appear to be receptor related. Thus different mechanisms for resistance to TGF‐β1 and TGF‐β2 were observed within a given clone. © 1993 Wiley‐Liss, Inc.
19F NMR studies of changes in membrane potential and intracellular volume during dexamethasone‐induced apoptosis in human leukemic cell lines
Authors: Adebodun Foluso , Post Jan F. M. 
Published: February 2005

AbstractThe induction of apoptosis in leukemic cells by dexamethasone is well known, but the mechanism of this type of cell death and of dexamethasone resistance by some variants is still poorly understood. Apoptotic cell death is preceded by many changes in cellular properties, such as glucose metabolism, cell size, cell density, and others. In this study, 19F‐NMR has been used to characterize changes in cell membrane potential and intracellular accessible volume during dexamethasone induced apoptosis. One dex‐sensitive (CEM‐C7) and three dex‐resistant variants (CEM‐C1, CEM‐ICR27, and CEM‐4R4) were examined. We have observed separate intracellular and extracellular resonances for trifluoroacetate and trifluoroacetamide added to suspended leukemic cells. From the equilibrium distribution of these fluoro‐compounds between intra and extracellular spaces, the changes in membrane potential and intracellular accessible volume were calculated. The membrane potential for CEM‐C7 cells was found to significantly decrease in the presence of dexamethasone (9‐mV decrease within 18 h of dexamethasone treatment), while that of CEM‐ICR27 was found in some samples to increase on dexamethasone incubation. The membrane potential for CEM‐C1 decreased slightly, while that of CEM‐4R4 was not appreciably affected by dexamethasone. The reduction of membrane potential seems to be an early step in the mechanism of dexamethasone induced apoptosis. Although the intracellular volume varied with cell type and dexamethasone incubation (for CEM‐C7), the fractional intracellular volume (α = Vin/Vcell was found to be the same (0.82 ± 0.06) for all the cell lines in the presence and absence of dexamethasone. © 1993 Wiley‐Liss, Inc.
Macrophage supernatants have both stimulatory and suppressive effects on mesangial cell proliferation
Authors: Mattana Joseph , Singhal Pravin C. 
Published: February 2005

AbstractMacrophages may modulate mesangial expansion following renal injury via secretory products. We undertook the present study to determine the effects of macrophages supernatants on mesangial cell proliferation. Macrophage supernatants collected in serum‐free media after 24 hours caused significantly enhanced mesangial cell proliferation in long‐term culture at concentration up to 50% but caused suppression at higher concentration (control, 122,000 ± 14,000 cells/well: 50% supernatant, 188,000 ± 15,100 cells/well, p < 0.02 compared to control, n = 4; 80% supernatant, 52,000 ± 3,500 cells/well, P < 0.01 compared to control, n = 4). In short‐term culture [3H] thymidine incorporation, a measure of DNA synthesis, was significantly enhanced compared to control at supernatant concentrations up to 30% (30% supernatant, 4,120 ± 310 cpm/well; control, 3,210 ± 97 cpm/well, P < 0.5, n = 4), but uptake was reduced at high concentration (80% supernatant, 2,900 ± 74 cpm/well; control, 3,210 ± 97 cpm/well, P < 0.05, n= 4) When macrophages supernatants were collected after 48 hours incubation and incubated with mesangial cells, mesangial cell thymidine uptake was significantly suppressed compared to control (48‐hours supernatant, 4,060 ± 260 cpm/well; control, 5,890 ± 270 cpm/well, P < 0.01, n = 4) and comapared to 24‐hour supernatants, which enhanced uptake (24‐hour supernatant, 8,080 ± 340 cpm/well; control, 5,890 ± 270 cpm/well, P < 0.01, n =4). Our results suggest that macrophages supernatants can directly enhance mesangial cell proliferation in vitro in both short‐term and long‐term culture, though this effect is lost at high concentrations of supernatant. These data lend support to the potential role of the macrophage in mediating mesangial expansion following renal injury. © 1993 Wiley‐Liss, Inc.
Middle ear cell line that maintains vectorial electrolyte transport
Authors: Herman P. , Cassigena R. , Friedlander G. , Soler P. , Grodet A. , Tran Ba Huy P. , Amiel C. 
Published: February 2005

AbstractThe middle ear epithelium plays a major role in keeping the temporal bone cavities fluid‐free and air‐filled, which is a mandatory condition to allow optimum transmission of the sound vibrations from the tympanic membrane to the inner ear. Previous works have recently established the absorptive function of the middle ear epithelium, using primary cultures derived from Mongolian gerbil (Meriones unguiculatus). Because of the paucity of cells as obtained by enzymatic digestion, we developed a middle ear cell line (MESV) using wild‐type SV40 infection of primary culture of Mongolian gerbil's middle ear epithelial cells. Transformation was attested by nuclear expression of SV40 large T antigen, prolonged in vitro passages (presently beyond 50 passages), and tumor‐inducing ability when subcutaneously injected in athymic mice. Transport properties were evaluated after the fifteenth passage. MESV cells retained most cardinal properties of the original middle ear epithelial cells: cell polarization was evidenced by the presence of mature junctional complexes that separate the cell membrane in two distinct domains, with apical microvilli at the luminal side, and by vectorial sodium transport responsible for the transepithelial lumen‐negative potential difference (−9.3 ± 0.14 mV in culture conditions (n=9), −2.1 ± 0.25 mV after overnight growth factors and serum deprivation). Short‐circuit current was, like in primary cultures, mainly related to a sodium transport occuring through amiloride‐sensitive apical sodium channels, since apical addition of amiloride (10−5 M) reduced Isc from 7.0 = 1.4 to 0.6 ± 0.1 μA/cm2 (P < 0.01, n = 6). Cellular cAMP content was increased by isoproterenol and prostaglandin E2 from 40.5 ± 5.6 to 258.5 ± 17.3 and 55.6 ± 6.2 pmol/mg protein per 5 min, respectively (P < 0.05, n = 10). Isoproterenol and prostaglandin E2 increased Isc with very similar maximal effects: isoproterenol (10−4 M) increased Isc from 5.73 ± 0.31 to 12.77 ± 0.39 μA/cm2, while prostaglandin E2 increased Isc from 5.47 ± 0.21 to 12.87 ± 0.42 (n = 3). Since amiloride (10−5 M) abolished this stimulation, this may be related to an increase of the electrogenic sodium transepithelial transport. The MESV cell line could provide an interesting tool as a model of middle ear epithelial cells for the study of pathophysiological modulations of ion transport. © 1993 Wiley‐Liss, Inc.
Ca2+ dependence of inositol 1,4,5‐trisphosphate‐induced Ca2+ release in renal epithelial LLC‐PK1 cells
Authors: Tshipamba M. , De Smedt H. , Missiaen L. , Himpens B. , Van Den Bosch L. , Borghgraef R. 
Published: February 2005

AbstractWe have studied arginine vasopressin (AVP)‐, thapsigargin‐ and inositol 1,4,5‐trisphosphate (InsP3)‐mediated Ca2+ release in renal epithelial LLC‐PK1 cells. AVP‐induced changes in the intracellular free calcium concentration ([Ca2+]i) were studied in indo‐1 loaded single cells by confocal laser cytometry. AVP‐mediated Ca2+ mobilization was also observed in the absence of extracellular Ca2+, but was completely abolished after depletion of the intracellular Ca2+ stores by 2 μM thapsigargin. Using 45Ca2+ fluxes in saponin‐permeabilized cell monolayers, we have analysed how InsP3 affected the Ca2+ content of nonmitochondrial Ca2+ pools in different loading and release conditions. Less than 10% of the Ca2+ was taken up in a thapsigargin‐insensitive pool when loading was performed in a medium containing 0.1 μM Ca2+. The thapsigargin‐insensitive compartment amounted to 35% in the presence of 110 μM Ca2+, but Ca2+ sequestered in this pool could not be released by InsP3. The thapsigargin‐sensitive Ca2+ pool, in contrast, was nearly completely InsP3 sensitive. A submaximal [InsP3], however, released only a fraction of the sequestered Ca2+. This fraction was dependent on the cytosolic as well as on the luminal [Ca2+]. The cytosolic free [Ca2+] affected the InsP3‐induced Ca2+ release in a biphasic way. Maximal sensitivity toward InsP3 was found at a free cytosolic [Ca2+] between 0.1 and 0.5 μM, whereas higher cytosolic [Ca2+] decreased the InsP3 sensitivity. Other divalent cations or La3+ did not provoke similar inhibitory effects on InsP3‐induced Ca2+ release. The luminal free [Ca2+] was manipulated by varying the time of incubation of Ca2+ ‐loaded cells in an EGTA‐containing medium. Reduction of the Ca2+ content to one‐third of its initial value resulted in a fivefold decrease in the InsP3 sensitivity of the Ca2+ release. © 1993 Wiley‐Liss, Inc.
Neutrophil adhesion to endothelial cells impairs the effects of catalase and glutathione in preventing endothelial injury
Authors: Siflinger‐Birnboim Alma , Malik Asrar B. 
Published: February 2005

AbstractWe studied the effects of the CuZn superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) on endothelial permeability to 125I‐albumin after activation of neutrophils (PMN) with phorbol 12‐myristate‐13‐acetate (PMA; 10−8M). PMN were either in direct contact with the endothelial cell monolayer grown on a porous gelatin‐coated microporous 10‐μm‐thick polycarbonate filter (upright system) or separated from the endothelium by a similar filter (inverted system). Transendothelial 125I‐albumin clearance rates were measured as an index of endothelial permeability. In the absence of antioxidants, activation of PMN increased transendothelial 125I‐albumin clearnace rates in both systems from 0.041 ± 0.006 μl/min (baseline) to 0.262 ± 0.18 μl/min (upright system) and from 0.063 ± 0.02 μl/min to 0.244 ± 0.06 μl/min (inverted system). PMA induced 80–90% of PMN to adhere to either gelatin‐coated filters or to endothelial cells, from the basal PMN adhesion value of 5.3 ± 2.2% and 4.3 ± 1.1%, respectively. SOD, which dismutates superoxide anion to hydrogen peroxide (H2O2), did not alter the transendothelial 125I‐albumin clearance rates in either systm at any concerntration from 10–300 U/ml. CAT (100–1,000 U/ml) and GSH (0.5–10 mM), which remove the H2O2 generated during PMN activation, did not alter the increase in transendothelial 125I‐clearance rates after PMN activation in the upright system, but both agents prvented the increase in transendothelial 125I‐clearance rates in the inverted system. We conclude that PMN activation with PMA causes endothelial injury irrespective of PMN contact to the endothelial monolayer. Moreover, H2O2, a release product of PMN activation, is a critical mediator of PMN‐dependent endothelial injury. Finally, the results indicate that CAT and GSH prevent endothelial injury only in the absence of direct PMN contact with endothelial cells, suggesting that antioxidants such as GSH and CAT are excluded from sites of PMN‐endothelial contact and thus are ineffective antioxidants. © 1993 Wiley‐Liss, Inc.
Interactive effects of nutrients and hormones on the expression of insulin‐like growth factor binding protein‐1 (IGFBP‐1) mRNA and peptide, and IGF I release from isolated adult rat hepatocytes
Authors: Arany E. , Strain A. J. , Hube M. J. , Phillips I. D. , Hill D. J. 
Published: February 2005

AbstractIsolated adult rat hepatocytes were used to investigate and compare the actions of glucose or amino acids and insulin, glucagon, growth hormone, and dexamethasone on the expression of insulin‐like growth factor binding protein (IGFBP) mRNA, or the release of IGFBP and IGF peptides in vitro. Ligand blot analysis of culture medium conditioned for 24 h by monolayers of hepatocytes in the presence of 6.5 mM glucose revealed two species of IGFBPs, and abundant form of 30‐32 kDa and a minor species of 22‐24 kDa. Western blotting showed that two IGFBPs of 29‐30 and 32 kDa were recognized by antiserum against hIGFBP‐1, whereas hepatocytes contained a 1.6 kb transcript on Northern blot with a rat IGFBP‐1 cDNA. Insulin‐like growth factor BP‐2 mRNA was not detected in hepatocytes and IGFBP‐2 immunoreactive peptide not present in conditioned medium. The release of IGFBP‐1, determined by ligand blot, was independent of gucose concentration over the range of 2.7 mM–11.1 mM, but IGFBP‐1 mRNA was decreased following incubation with 6.5 mM gucose compared with 2.7 mM glucose. The release of IGFBP‐1 by hepatocytes was inhibited by insulin (10nM–1μM), as was mRNA abundance. However, these effects of insulin on IGFBP‐1 diminished with increasing glucose concentration. Increasing concentrations of total amino acids increased IGFBP‐1 release as did dexamethasone (100 pM–100nM), whereas growth hormone and gucagon were without effect. The release of IGF I was increased by insulin, growth hormone and dexamethasone but was decreased by glucagon and amino acids, whereas changes in glucose concentration had no effect. The results show that isolated adult rat hepatocytes release IGF I and IGFBP‐1 under the interactive control of nutrients and hormones involved in metabolic homeostasis. © 1993 Wiley‐Liss, Inc.
Growth promotion of transfected hepatoma cells by liver fatty acid binding protein
Authors: Keler Tibor , Sorof Sam 
Published: February 2005

AbstractFormer studies have linked hepatocyte growth with liver fatty acid binding protein (L‐FABP) of rat liver cytosol. In search for the roles of L‐FABP in hepatocytes, we previously stably transfected rat L‐FABP sense and antisense cDNAs into rat hepatoma HTC cells that do not contain L‐FABP RNA or protein, thereby providing a zero‐background, homologous cell model of L‐FABP‐expression suitable for controlled studies of its intracellular functions in hepatocyte‐derived cells. The present study demonstrates the abilities of L‐FABP to promote DNA synthesis and cell growth, preserve cell morphology, extend survival, and act cooperatively with unsaturated fatty acids in the transfected hepatoma cells in the absence of serum. Following removal of serum, the three control L‐FABP‐nonexpressing cell lines increased in cell lines increased in cell number for 24 hr and thereafter declined, whereas the three L‐FABP‐expressing cell lines exhibited a 39% higher rate of DNA synthesis per cell at 24 hr and grew in cell number for 48 hr. As a result, at 72 hr there were 2.5‐fold (avg.) as many L‐FABP‐expressing cells than L‐FABP‐nonexpressing cells. In addition, the L‐FABP‐expressing cells retained their original polygonal morphology at 48 hr, when in contrast most of the control nonexpressing cells were spherical in shape with membrane blebs. In an effort to identify the agonists that collaborate with L‐FABP in the growth promotion and preservation of cell morphology, various free fatty acids were examined at 48 hr for their ability to elminate the differences in behavior of the two cell types in the serum‐free medium. The unsaturated fatty acids, oleic acid (18:1 ω9), linoleic acid (18:2ω6), α‐linolenic acid (18: 3ω3), and arachidonic acid (20:4ω6), at 1 μM markedly elevated the level of DNA synthesis in the more depressed control L‐FABP‐nonexpressing cells and moderately raised it in the less depressed L‐FABP‐expressing cells. In accord, the control L‐FABP‐nonexpressing cells needed 10−6–10−5 M linoleic acid to achieve the extent of DNA synthesis attained by the expressing cells in the absence of added fatty acid. At 10 μM linoleic acid, their levels of DNA synthesis were equal. In contrast, five saturated fatty acids had no detectable effect on DNA synthesis. In addition, linoleic acid at 1 μM, but not the saturated fatty acid palmitic acid (16:0), prevented the above morphological alterations in the control L‐FABP‐nonexpressing cells observed in the absence of serum, thereby retaining their original polygonal morphology and that of the expressing cells. The findings are consistent with the concept that L‐FABP improves the efficacy of the utilization of unsaturated fatty acid ligands of L‐FABP in the formation, integrity, and fluidity of cell membranes that are involved in cell growth, morphology, and survival. © 1993 Wiley‐Liss, Inc.