bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sequential expression of cell surface C3bi receptors during neutrophil locomotion
Authors: Francis Joseph W. , Todde Robert F. , Boxer Laurence A. , Petty Howard R. 
Published: February 2005

AbstractFluorescence microscopy has been used to study the cell surface distribution of the complement receptor for C3bi (CR3) on human neutrophils during locomotion. CR3 is an integral membrane protein that participates in cell attachment phenomena including chemotaxis. Fluorescein‐ and rhodamine‐conjugated monoclonal IgG or Fab fragments were used to label CR3. We have previously shown that CR3 is uniformly distributed on unstimulated cells. During cell locomotion the fluorescent labels redistribute to the uropod and retraction fibers. To better understand the role of CR3 in chemotaxis, we have performed sequential two‐color labeling experiments in conjunction with fluorescence microscopy. Double‐labeling experiments were conducted by labeling adherent neutrophils with fluorescein‐conjugated anti‐CR3 followed by chemotaxis in a gradient of FMLP (10‐7 M). The cells were then labeled again with rhodamine‐conjugated anti‐CR3. The uropod and distal training filopodia were labeled with fluorescein, whereas the cell body and occasionally proximal filopodia near the uropod were labeled with rhodamine. When neutrophils were fixed and permeabilized prior to the second CR3 labeling, the second fluorescent label was localized to a granule‐like compartment(s), often near the lamellipodium. The results suggest a flow of CR3 from intracellular granules → lamellipodia and cell body → uropod → trailing filopodia during chemotaxis.
Effects of platelet‐derived growth factor on bone formation in vitro
Authors: Canalis Ernesto , McCarthy Thomas L. , Centrella Michael 
Published: February 2005

AbstractPlatelet‐derived growth factor (PDGF) is a polypeptide found in a variety of tissues, including bone, where it could act as an autologous regulator of skeletal remodeling. Therefore, a recombinant B chain homodimer of human PDGF was studied for its effects on bone formation in cultured rat calvariae. PDGF at 10‐100 ng/ml stimulated [3H]thymidine incorporation into DNA by up to sixfold and increased the DNA content and the number of colcemid‐induced metaphase arrested cells. This effect was observed in the fibroblast and precursor cell‐rich periosteum. As a result of its mitogenic actions, PDGF enhanced [3H]proline incorporation into collagen, an effect that was observed primarily in the osteoblast‐rich central bone. The effect of PDGF was not specific for collagen since it also increased noncollagen protein synthesis. In addition, PDGF increased bone collagen degradation. PDGF and insulin‐like growth factor (IGF) I had additive effects on calvarial DNA synthesis, but PDGF opposed the stimulatory effect of IGF I on collagen synthesis and IGF I prevented the PDGF effect on collagen degradation.In conclusion, PDGF stimulates calvarial DNA synthesis which causes an increased number of collagen‐synthesizing cells, but PDGF also enhances bone collagen degradation.
Heparin‐derived oligosaccharides: Affinity for acidic fibroblast growth factor and effect on its growth‐promoting activity for human endothelial cells
Authors: Bârzu Tereza , Lormeau Jean‐Claude , Petitou Maurice , Michelson Susan , Choay Jean 
Published: February 2005

AbstractThe minimal structural requirements for the interaction of heparin with acidic fibroblast growth factor (aFGF) were investigated. Oligosaccharides (tetra‐ to decasaccharides) obtained by nitrous acid depolymerisation of standard heparin were separated by affinity chromatography on Sepharose‐immobilised aFGF. The shortest fragment retained by the affinity column at 0.2 M NaCl and eluted at 1 M NaCl was a “regular” hexasaccharide, a trimer of the most abundant disaccharide sequence in heparin. More complex octa‐ and decasaccharides were also retained by the column. The Oligosaccharides eluted by 1 M NaCI from the affinity column (“high‐affinity” Oligosaccharides) and those washed from the column at 0.2 M NaCI (“low‐affinity” Oligosaccharides) were compared for their capacity to protect aFGF from proteolysis and to potentiate its mitogenic activity. At a low ionic strength, all Oligosaccharides tested, except the “regular” disaccharide, protected aFGF againsttrypsin and collagenase digestion. At higher ionic strength (> 0.2 M NaCI), only high‐affinity Oligosaccharides showed a protective effect. The high‐affinity oligosaccharides (hexa‐ to decasaccharides) potentiated the mitogenic activity of aFGF, as measured by [3H]thymidine incorporation into DNA of human fibroblasts. The effect of the oligosaccharides on human endothelial cell proliferation was more complex: inhibition of proliferation was observed in the presence of serum and low concentrations of aFGF (1‐5 ng/ml) and potentiation in the presence of higher concentrations of aFGF. The potentiating effect increased as a function of molecular size of the heparin fragments and, for a given size, as a function of the anionic charge of the oligosaccharide. Our results suggest that inhibition of cell proliferation by heparin may result from interference with an autocrine basic FGF‐like activity.
Adenosine triphosphate, bradykinin, and thyrotropin‐releasing hormone regulate the intracellular Ca2+ concentration and the 45Ca2+ efflux of human thyrocytes in primary culture
Authors: Raspè E. , Andry G. , Dumont J. E. 
Published: February 2005

AbstractThe hormonal stimulation of phospholipase C and the consequent activation of the Ca2+‐phosphatidylinositol cascade in eukaryotic cells is associated with modifications of the [Ca2+] (intracellular Ca2+ concentration) which modulates cellular functions. In this study, these modifications were investigated in primary cultures of human thyroid cells.The mean apparent basal [Ca2+] of human thyrocytes measured using the intracellularly trapped fluorescent indicator Quin‐2 was found to be 89°C 16 nM (n = 49). ATP and, to a lesser extent, ADP, but not AMP or adenosine, elicited a concentration‐dependent biphasic rise in human thyrocytes [Ca2+] and increased their 45Ca2+ efflux. The first transient phase of the [Ca2+] rise induced by ATP was resistant to extracellular Ca2+ depletion, whereas the second sustained phase was abolished in these conditions. This suggests that although the first phase of this response involves a release of Ca2+ from intracellular stores, the second phase requires extracellular Ca2+ influx. The response of human thyro‐cytes to analogs of ATP is compatible with a P2‐purinergic effect of ATP on these cells. Bradykinin and TRH affected the human thyrocyte [Ca2+] and 45Ca2+ efflux similarly to ATP. The human thyrocyte [Ca2+] and the 45 Ca2+ efflux were not modified by carbachol, a nonhydrolyzable analog of acetylcholine.The present results suggest the presence of P2‐purinergic receptors to ATP and of receptors to TRH and bradykinin on human follicular thyroid cells. They also confirm that the Ca2+‐phosphatidylinositol cascade is present in these cells and suggest that this cascade is modulated by ATP, TRH, and bradykinin. As this cascade is involved in the regulation of protein iodination, and therefore of thyroid hormones synthesis, these agents might have an important role in the regulation of the thyroid function.
Neutral amino acid transport in human synovial cells: Substrate specificity of adaptative regulation and transinhibition
Authors: Aussel Christian , Rousseau‐Loric Sophie , Cynober Luc , Agneray Jean , Ekindjian Ohvanesse G. 
Published: February 2005

AbstractNeutral amino acid transport was characterized in human synovial cells. The amino acids tested are transported by all three major neutral amino acid transport systems, that is, A, L, and ASC. The model amino acid 2‐aminoisobutyric acid (AIB) was found to be a strong specific substrate for system A in synovial cells. When cells were starved of amino acids, the activity of AIB transport increased, reaching a maximum within 1 h. The stimulation of transport activity was not blocked by cycloheximide and would thus appear to be related to a release from transinhibition. Similarly, the decrease in the activity of AIB transport observed after the addition of α‐methyl‐aminoisobutyric acid (meAIB) appeared to be related to transinhibition. However, using a different approach, that is, amino acid starvation followed by incubation with 10 mM meAIB and transfer to an amino acid‐free medium with or without cycloheximide supplementation, a clear increase in AIB uptake, due both to derepression and a release from transinhibition, was observed. Unlike human fibroblasts, the derepression of system A in these synovial cells was not serum‐dependent. The process of derepression was observed only after preloading with meAIB. Neither AIB nor alanine produced this phenomenon. Moreover, alanine preloading led to a large increase in AIB transport activity due to a release from transinhibition. These observations indicate that the process of derepression and release from transinhibition are specific to the substrates present in the culture medium prior to amino acid starvation.
Induction of polarized apical expression and vectorial release of carcinoembryonic antigen (CEA) during the process of differentiation of HT29‐D4 cells
Authors: Fantini Jacques , Rognoni Jean‐Baptiste , Culouscou Jean‐Michel , Pommier Gilbert , Marvaldi Jacques , Tirard Alain 
Published: February 2005

AbstractHT29‐D4 clonal cells can be induced to differentiate by a simple alteration of the culture medium, that is, by the replacement of glucose by galactose [Fantini, J., et al. (1986) J. Cell Sci., 83:235–249] as reported for the nonclonal HT29 cells [Pinto, M., (1982) Biol. Cell, 44:193–196]. An essential property of the HT29‐D4 cell line is the fact that no cell loss occurs after the medium change, so that the differentiated cells can be considered as the true counterpart of the undifferentiated one. This model is particularly suitable to study morphological and biochemical events associated with the progressive establishment of the differentiation state.We report here that Carcinoembryonic antigen (CEA), a 180 kDa glycoprotein originally described as a colon tumor associated antigen, is faintly expressed at the surface of undifferentiated HT29‐D4 cells. These cells release a small amount of CEA (2.5 ng/106 cells/24 hr) in the culture medium. Fourty‐eight hours after glucose substitution by galactose, both CEA cell surface expression and release are strongly enhanced as demonstrated by immunofluorescence and immuno‐precipitation studies. Ten days after the medium change, the amount of CEA released reaches a maximum value of 130 ng/106 cells/24 hr, which remains stable for differentiated HT29‐D4 cells cultured in glucose‐free, galactose‐containing medium (Gal‐medium) for several months.HT29‐D4 cells grown in Gal‐medium in porous‐bottom culture dishes generate leakproof epithelial monolayers. We have successfully performed an independent radioiodination of the apical and basolateral domains of these cells, followed by immunoprecipitation. We demonstrate that CEA is expressed exclusively at the apical surface of differentiated HT29‐D4 cells, since the 180 kDa polypeptide was immunoprecipitated only when the radioiodination was performed at the apical side of the monolayer.Leakproof HT29‐D4 monolayers cultured in permeable chambers were also used to demonstrate that CEA was exclusively released in the medium bathing the apical side of the cells. In conclusion, this study of cell surface CEA expression and CEA release during the process of differentiation of HT29‐D4 cells demonstrated that (1) CEA cell surface expression and CEA release are correlated with cell differentiation; (2) CEA is expressed in the apical brush border membrane of differentiated HT29‐D4 cells; and (3) CEA release is exclusively oriented toward the apical side of the polarized monolayer.
Possible role of prostaglandins in the regulation of mouse myoblasts
Authors: Rossi Michael J. , Clark Mike A. , Steiner Sheldon M. 
Published: February 2005

AbstractA differentiation‐defective mouse myoblast subclone (DD‐1), cells of which do not fuse into myotubes nor synthesize muslce‐specific proteins, was employed to help define the role of eicosanoids in mouse myoblast differentiation. We observed by hplc, tIc, and radioimmunoassay that the DD‐1 cells release strikingly higher levels of cyclooxygenase pathway products prostaglandin E2 and F2α into the culture medium than the parental non‐differentiation‐defective cells (DZ). In contrast, the levels of 15‐hydroxyeicosatetraenoic acid (15‐HETE), a lipoxygenase product, and a putatively identified second lipoxygenase product (LLP) did not differ greatly in the two cell types. The DD‐1 cells also have strikingly higher levels of cyclooxygenase activity than the parental cells as determined by intact and broken cell assays. Additional fusion‐defective clones were isolated on the basis of their flattened appearance and ability to grow in “mitogen‐poor” medium and these cells also released strikingly higher levels of prostaglandins E2 and F2α into the growth medium. The “turn on” of the cyclooxygenase pathway in the DD‐1 cells and other fusion‐defective cells is consistent with the hypothesis that the products of this pathway contribute to the inability of myoblasts to fuse with one another. This hypothesis is supported by the observation that there is a dose‐dependent decrease in fusion of DZ cells when PGE2 is added to commitment medium.
Intranuclear distribution of the human myeloid cell nuclear differentiation antigen in HL‐60 cells
Authors: Duhl David M. , Gaczynski Marek , Olinski Ryszard , Briggs Robert C. 
Published: February 2005

AbstractBased on solubility properties, the human myeloid cell nuclear differentiation antigen exists as at least two distinct populations. Most is easily extracted from isolated nuclei in 0.35 M NaCl, while 20 percent resists such treatment. Compared to undigested nuclei, both the amount of myeloid cell nuclear differentiation antigen (MNDA) released from nuclei after DNase I treatment and the amount resisting further extraction in 0.35 M NaCl increased after DNA was digested with DNase I. Under these conditions, there was a concomitant decrease in the amount of MNDA that was extractable with 0.35 M NaCl. Mixing nuclear protein extracts that contain MNDA with nuclei from cells that do not express this protein demonstrated that the MNDA redistributes from the freely soluble form to the nuclear residual fraction as a consequence of DNase I digestion. These data are consistent with a model in which the amount of MNDA that is tightly bound to salt‐washed nuclei is held constant in the presence of an excess of unassociated MNDA in the nucleus, and that the level of MNDA binding to this nuclear fraction increases in proportion to the extent of DNA damage resulting from DNase I digestion.
Interleukin‐1 is a potent regulator of JE and KC gene expression in quiescent BALB/c fibroblasts
Authors: Hall David J. , Brownlee Clare , Stiles Charles D. 
Published: February 2005

AbstractInterleukin‐1 alpha and beta are polypeptide hormones with a broad range of biological activities. Both interleukins are recognized by a receptor that has been characterized as a member of the immunoglobin superfamily. The interleukin‐1 receptor does not appear to be a tyrosine protein kinase. Moreover, the intracellular events that mediate the multiple interleukin‐1 responses are poorly understood. Here we show that the JE and KC genes, first isolated and characterized as platelet‐derived growth factor inducible in quiescent BALB/c‐3T3 fibroblasts, are induced by femtomolar concentrations of recombinant interleukin‐1 alpha (rlL‐1). The response of JE and KC to IL‐1 occurs at the transcriptional level. These observations suggest that an analysis of the JE and KC transcriptional response to rlL‐1 may aid in identifying elements involved in interleukin‐1‐mediated signal transduction.
Maintenance of proximal and distal cell functions in SV40‐transformed tubular cell lines derived from rabbit kidney cortex
Authors: Vandewalle A. , Lelongt B. , Geniteau‐Legendre M. , Baudouin B. , Antoine M. , Estrade S. , Chatelet F. , Verroust P. , Cassingena R. , Ronco P. 
Published: February 2005

AbstractThis paper reports the preparation and describes the properties of three renal tubular cell lines derived using SV40 infection of primary cultures of rabbit kidney cortical cells, enriched in proximal cells. RC.SV1 was initially derived from cultures grown in the presence of fetal calf serum exhibiting a low degree of proximal differentiation. The cells were subsequently adapted to grow in serum‐free hor‐monally defined medium and display basic properties of proximal tubule cells including well‐developed apical microvilli, strong expression of brush‐border hydrolases, Na+‐coupled glucose uptake, and increased cyclic AMP production when exposed to PTH. The other two cell lines were derived from cultures in serum‐free hormonally defined medium and propagated in the same medium. They are characterized by some common properties including rare and short microvilli, low expression of apical hydrolases, and low or undetectable Na+‐dependent glucose uptake, but differ by their abilities to respond by an increase in cAMP to various hormonal stimuli. RC.SV2 cells are sensitive to calcitonin and to a lesser extent to isoproterenol and PTH, suggesting that they may originate from the thick ascending limb of Henle's loop and the bright portion of the distal tubule. RC.SV3 responds essentially to isoproterenol and arginine va‐sopressin, suggesting a more distal origin (late distal and initial collecting tubule). Emergence of distal cell lines from cultures exhibiting proximal characteristics may be related to distal cell overgrowth as suggested by analysis of growth kinetics and increased Na+/H+ exchanger activity in RC.SV2 compared with RC.SV1.
Lipocortin I (p35) is abundant in a restricted number of differentiated cell types in adult organs
Authors: Fava Roy A. , McKanna James , Cohen Stanley 
Published: February 2005

AbstractLipocortin‐l (p35) is a unique calcium‐ and phospholipid‐binding protein of the lipocortin/calpactin family. Although several possibilities have been suggested, functions for the individual proteins of this family are not yet known with certainty. As an initial step in the identification of the biological function(s) of p35, we have used immunohistochemical methods to define precisely many of the cellular phenotypes that contain p35 in vivo. In all organs where p35 is found, we have observed a striking distribution of p35‐positive cells. Typically it is highly enriched in a limited range of differentiated cell types while apparently totally absent from most others. Our identification of specific p35‐positive cell types in vivo will now set limitations on likely possibilities for functions of this protein and thereby permit a more logical approach to the determination of its true function.
Transforming growth factors type β1 and β2 are equipotent growth inhibitors of human breast cancer cell lines
Authors: Zugmaier Gerhard , Ennis Bruce W. , Deschauer Bernd , Katz Deborah , Knabbe Cornelius , Wilding George , Daly Peter , Lippman Marc E. , Dickson Robert B. 
Published: February 2005

AbstractAt least one member of the TGF‐β family, TGF‐β1, has been previously shown to inhibit the anchorage‐independent growth of some human breast cancer cell lines (Knabbe et al., 1987; Arteaga et al., 1988). Members of the TGF‐β family might, therefore, provide new strategies for breast cancer therapy. We have studied the inhibitory effects of TGF‐β1 and TGF‐β2 on the anchorage‐independent growth of the estrogen receptor‐negative cell lines MDA‐MB‐231, SK‐BR‐3, Hs578T, MDA‐MB‐468, and MDA‐MB‐468‐S4 (an MDA‐MB‐468 clone not growth inhibited by EGF) and the estrogen receptor‐positive cell lines MCF7, ZR‐75‐1, T‐47D. TGF‐β1 and TGF‐β2 caused a 75–90% growth inhibition of MDA‐MB‐231, SK‐BR‐3, Hs578T, and MDA‐MB‐468 cells and a 50% growth inhibition of ZR‐75‐1 and early passage (< 100) MCF7 cells. T‐47D cells responded to TGF‐β only in serum‐free conditions in the presence of IGF‐1 or EGF. The growth of MDA‐MB‐468‐S4 cells and late passage (> 500) MCF7 cells was not inhibited by TGF‐β1 or TGF‐β2. TGF‐β‐sensitive MCF7 and MDA‐MB‐231 cells did not respond to Muellerian inhibiting substance (MIS), a TGF‐β‐related polypeptide. TGF‐β1 and TGF‐β2 were mutually competitive for receptor binding with a similar affinity (Kd 25‐130 pM, 1,000‐13,000 sites per cell). To determine the time course of the TGF‐β effect, an anchorage‐dependent growth assay was carried out using MDA‐MB‐231 cells. Growth inhibition occurred at 6 days, and cell‐cycle changes were seen 12 hr after the addition of TGF‐β. Cells accumulated in the G1 phase and were thus inhibited from entering the S‐phase. These data indicate that TGF‐β is a potent growth inhibitor in most breast cancer cell lines and provide a basis for studying TGF‐β effects in vivo.
Identification of alpha transforming growth factor as a possible local trophic agent for the mammary gland
Authors: Smith J. A. , Barraclough R. , Fernig D. G. , Rudland P. S. 
Published: February 2005

AbstractBiologically active alpha‐transforming growth factor (α‐TGF) has been identified in medium conditioned by rat mammary myoepithelial and, to a lesser extent, by epithelial cell lines in culture and in the rat mammary gland. The α‐TGF has been identified by its wide spectrum of activity in promoting growth of mammary‐derived cells in vitro, by its chromatographic behaviour on reversed‐phase high‐performance liquid chromatography (HPLC), by its competition with epidermal growth factor (EGF) for the EGF receptor, and by the presence of messenger RNA for α‐TGF in the secreting cells. In vivo the amount of α‐TGF isolated is sixfold greater from the mammary glands of lactating than from those of virgin female rats. It is proposed that α‐TGF is produced by the myoepithelial cells of the mammary gland, as a local trophic agent that stimulates growth of the various cell types of the gland.
Cyclic adenosine monophosphate acts synergistically with dexamethasone to inhibit the entrance of cultured adult rat hepatocytes into S‐phase: With a note on the use of nucleolar and extranucleolar [3H]‐thymidine labelling patterns to determine rapid changes in the rate of onset of DNA replication
Authors: Vintermyr Olav Karsten , Mellgren Gunnar , Bøe Roald , Døskeland Stein Ove 
Published: February 2005

AbstractAnalogs of cyclic adenosine monophosphate (cAMP) (N6benzoyl cAMP and N6monobutyryl cAMP) as well as agents that increased the intracellular level of cAMP (glucagon and isobutylmethylxanthine) inhibited the EGF‐stimulated DNA replication of adult rat hepatocytes in primary culture independently of cell density. This inhibition was strongly potentiated by the glucocorticoid dexamethasone. The effect of cAMP (and dexamethasone) was not due to toxicity, because the inhibition was reversible and the cell ultrastructure preserved. cAMP acted by decreasing the rate of transition from G1‐ to S‐phase, the duration of G2‐ and S‐phase of the hepatocyte cell cycle being unaffected. DNA replication started in the extranucleolar compartment of the nucleus and ended in the nucleolar compartment as described earlier for cells grown in the absence of cAMP (O.K. Vintermyr and S.O. Døskeland, J. Cell. Physiol., 1987, 132:12‐21). The action of cAMP was very rapid: significant inhibition of the transition was noted 2 hr after the addition of glucagon/IBMX and half‐maximal inhibition after 4 hours. The determination of extranucleolarly labelled nuclei in cells pulse‐labelled with [3H]thymidine allowed precise analysis of rapid changes in the probability of transition from G1‐ to S‐phase. The extranucleolar labelling index could also be determined in cells continuously exposed to [3H]thymidine.