bluuebunny/crossref_metadata_2025_split huggingface dataset:
Second messenger signaling in the regulation of cytosolic pH and DNA synthesis by parathyroid hormone (PTH) and PTH‐related peptide in osteoblastic osteosarcoma cells: Role of Na+/H+ exchange
Authors: Sugimoto Toshitsugu , Kano Junichi , Fukase Masaaki , Fujita Takuo 
Published: February 2005

AbstractThe present study was performed to investigate the regulation of cytosolic pH (pHi) and DNA synthesis by parathyroid hormone(PTH) and PTH‐related peptide (PTHrP) in osteoblasts, using osteoblastic osteosarcoma cells, UMR‐106 which possessed PTH‐responsive dual signal transduction systems (cAMP‐dependent protein kinase (PKA) and calcium/protein kinase C [Ca/PKC]) and amilorideinhibitable Na+/H+ exchange system. Both human (h)PTH‐(1–34) and hPTHrP‐(1–34) caused a progressive decrease in pHi and the inhibition of [3H]thymidine incorporation (TdR) to the same degree in a dose‐dependent manner with a minimal effective dose of 10−10 M. Dibutyryl cAMP (10−4 M) and Sp‐cAMPS (10−4 M), a direct stimulator of PKA also caused a progressive decrease in pHi, and calcium ionophores (A23187 and ionomycin, 10−6 M) caused a transient decrease in pHi. Pretreatment with amiloride (0.3 mM) mostly blocked dbcAMP‐and Sp‐cAMPS‐induced decrease in pHi but did not affect calcium ionophore‐induced decrease in pHi. In the presence of amiloride, PTH and PTHrP caused a transient decrease in pHi, which was similar to the pattern of calcium ionophore‐induced change in pHi. Amiloride did not affect the inhibition of TdR by PTH or PTHrP as well as that by cAMP analogues or calcium ionophores. The present study indicated that PTH and PTHrP caused cytosolic acidification through PKA‐inhibited Na+/H+ exchange and increased cytosolic calcium‐induced pathway and that the regulation of DNA synthesis by PTH and PTHrP was not via Na+/H+ exchange system. © 1992 Wiley‐Liss, Inc.
Protein kinase C has both stimulatory and suppressive effects on macrophage superoxide production
Authors: Phillips Wayne A. , Croatto Maryann , Veis Nurin , Hamilton John A. 
Published: February 2005

AbstractUnlike resident peritoneal macrophages (RPM) or tumor necrosis factor α (TNFα)‐primed bone marrow‐derived macrophages (BMM), unprimed BMM do not generate superoxide in response to the protein kinase C (PKC) activator, phorbol myristate acetate (PMA). However, these cells do contain significant levels of PKC activity. In contrast to PMA, zymosan induces the generation of superoxide in unprimed BMM, as well as in TNFα‐primed BMM and RPM. Staurosporine, a potent PKC inhibitor, failed to affect the zymosan‐induced production of superoxide by unprimed and TNFα‐primed BMM and RPM, in spite of substantial inhibition of PMA‐induced superoxide production by the primed BMM and RPM. However, when PKC was depleted from unprimed BMM by prolonged (24 h) treatment with phorbol dibutyrate (PdBt) (10−7 M) the ability of zymosan to induce the production of superoxide was greatly diminished. Such a result could be interpreted as suggesting a role for PKC in the zymosan‐induced response a conclusion which contrasts with the inhibitor data. However, PKC depletion, in this case, is achieved via the PdBt‐induced activation of PKC. It is thus possible that it is the initial activation of PKC, rather than its depletion, that suppresses superoxide production. Consistent with this interpreation, the co‐stimulation of unprimed BMM with both zymosan and PMA resulted in a reduced superoxide release compared to zymosan alone. The activation of PKC therefore appears to have a suppressive effect on the generation of superoxide by unprimed cells. We thus conclude that PKC is not required for zymosan‐induced superoxide production by either primed or unprimed macrophages and suggest that PKC may be involved in regulatory mechanisms restricting superoxide production by macrophages. However, since PMA alone can initiate the release of superoxide from primed BMM and RPM, it would appear that PKC can mediate both stimulatory and suppressive signals for macrophage superoxide production. © 1992 Wiley‐Liss, Inc.
Imaging neutrophil activation: Analysis of the translocation and utilization of NAD(P)H‐associated autofluorescence during antibody‐dependent target oxidation
Authors: Liang Bing , Petty Howard R. 
Published: February 2005

AbstractFluorescence intesified/enhanced microscopy has been used to study the metabolic activation of living human neutrophils in time‐lapse sequences. The autofluorescence associated with NAD(P)H's emission band was studied within individual quiescent and stimulated cells. Excitation of NAD(P)H‐associated autofluorescence was provided by a high‐intensity Hg‐vapor lamp. The background‐subtracted autofluorescence signals were computer enhanced. In some cases the ratio image of NAD(P)H‐associated autofluorescence to tetramethylrhodamine methyl ester (TRME) fluorescence, which was found to be uniformly distributed within neutrophils, was calculated to normalize autofluorescence intensities for cell thickness. Activation of the NADPH oxidase by phorbol myristate acetate, F−, N‐formyl‐methionyl‐leucyl‐phenylalanine (FMLP), or tumor necrosis factor (TNF) dramatically reduced autofluorescence levels. Membrane solubilization with sodium dodecyl sulfate eliminated autofluorescence. Thus, control experiments indicated that most or all of the detectable NAD(P)H‐associated autofluorescence was due to NAD(P)H, consistent with previous non‐microscopic studies. To understand the metabolic events surrounding the internalization and oxidative destruction of targets, we have imaged the NAD(P)H‐associated autofluorescence of neutrophils and the Soret band of antibody coated target erythrocytes during cell‐mediated cytotoxicity. Absorption contrast microscopy of the erythrocyte's Soret band is an especially sensitive indicator of the entry of reactive oxygen metabolites into this target's cytosol. Thus, it is possible to spectroscopically dissect and image the substrate (NADPH) and product (O2−) reactions of the NADPH oxidase in living unlabeled neutrophils. During real‐time experiments at 37°C, the level of NAD(P)H‐associated autofluorescence surrounding phagosomes greatly increases before the disappearance of the target's Soret band. NAD(P)H‐associated autofluorescence in the vicinity of phagocytosed erythrocytes is greatly diminished after target oxidation. This suggests that NAD(P)H is translocated to the vicinity of phagosomes prior to the oxidation of targets. The apparent cytosolic redistribution of NAD(P)H was confirmed by ratio imaging microscopy to control for cell thickness. We suggest that NADPH including its sources and/or carriers accumulate near phagosomes prior to target oxidation and that local NADPH molecules are consumed during target oxidation. © 1992 Wiley‐Liss, Inc.
K‐current mediation of prolactin‐induced proliferation of malignant (Nb2) lymphocytes
Authors: Wang Yu‐Fen , Jia Hongjun , Walker Ameae M. , Cukierman Samuel 
Published: February 2005

AbstractThe effects of different concentrations of various K‐current blockers on prolactin‐induced proliferation and membrane K‐currents in malignant lymphocytes (Nb2 cells) were investigated. Membrane currents were measured with the whole cell patch‐clamp technique, and lymphocyte density was quantified by both spectrophotometric and conventional methods. K‐current blockers tested (quinidine, 4‐aminopyridine, barium, and tetraethylammonium) exhibited similar rank order potency for K‐current block and inhibition of prolactin‐induced proliferation of malignant lymphocytes. Because Nb2 cells proliferate independently of a transmembrane Ca‐influx, these results suggest that K‐currents per se rather than K‐current modulation of Ca‐influx is an essential event for lymphocyte proliferation. © 1992 Wiley‐Liss, Inc.
Production of granulocyte colony‐stimulating factor and granulocyte/macrophage‐colony‐stimulating factor after interleukin‐1 stimulation of marrow stromal cell cultures from normal or aplastic anemia donors
Authors: Migliaccio Anna Rita , Migliaccio Giovanni , Adamson John W. , Torok‐Storb Beverly 
Published: February 2005

AbstractWe have studied stromal cell function in naive or interleukin‐1 (IL‐1)‐stimulated (100 pg/ml) long‐term marrow cultures (LTC) from 12 normal donors and 21 patients with severe aplastic anemia (AA). Conditioned media (CM) from normal LTC contained levels of erythroid burst‐promoting activity (BPA) and granulocyte/macrophage (GM) colony‐stimulating activity (CSA) comparable to those previously described (Migliaccio et al., [1990] Blood, 75:305–312). The addition of IL‐1 to these cultures increased the level of CSA and, specifically, of granulocyte colony‐stimulating factor (G‐CSF) released. Anti‐GM‐CSF antibody neutralized BPA and CSA in normal naive LTC CM but only the CSA in the CM from IL‐1‐stimulated LTC. Since the concentrations of GM‐CSF, as detected with a specific immunoassay, did not increase after IL‐1 treatment, these data suggest that IL‐1‐stimulated cultures contain an unidentified growth factor having BPA. CM from AA stromal cells contained levels of CSA comparable to those observed in normal stromal cell CM but had significantly lower levels of BPA. Neither anti‐GM‐CSF nor anti‐IL‐3 antibodies neutralized the BPA in AA stromal cell CM. This activity may be related to that found in the CM of IL‐1‐treated normal stromal cells. In nearly 50% of stromal cell cultures of AA patients, addition of IL‐1 failed to increase the BPA, CSA, or G‐CSF. The presence of an inhibitor in naive or IL‐1‐treated AA stromal cell CM was excluded by adding the CM to IL‐3‐stimulated cultures. These findings suggest that G‐CSF and GM‐CSF genes are differentially regulated in the marrow microenvironment. Furthermore, a marrow microenvironment, deficient in BPA production and, in some cases, unresponsive to IL‐1 could contribute to marrow failure in some patients with AA. © 1992 Wiley‐Liss, Inc.
Effect of hypoxia upon intracellular calcium concentration of human endothelial cells
Authors: Arnould Thierry , Michiels Carine , Alexandre Isabelle , Remacle José 
Published: February 2005

AbstractIschemia is a situation occurring in several diseases including myocardial infarction and organ transplantation in which oxygenated blood supply is impaired. Ischemia leads to many cellular and tissue modifications, the most important one being cell death. Several explanations have been proposed to account for these modifications and cell death; among them is calcium overload. However, the influence of calcium concentration on the alteration of endothelial cell functions or viability during ischemia are still unknown. We developed here an in vitro model where human endothelial cell monolayers were submitted to hypoxia with or without reoxygenation and variation in calcium concentration was followed using a specific intracellular probe Fura 2.We observed a significant increase of [Ca2+]i during 2 h hypoxia reaching values similar to those observed during agonist stimulation of endothelial cells but far lower than values toxic for the cells. This increase was constant during the hypoxic incubation and was due mainly to an influx of extracellular calcium. Viability was also followed during hypoxia and using calcium channel blockers, we could show that there was no correlation between viability and the rise in calcium concentration. During the reoxygenation period, [Ca2+]i decreased to reach the normal value of resting cells after 45 min, suggesting that cells were still able to recover their calcium homeostasis. The use of a ketone body (β‐hydroxybutyrate) indicated that an energy deficiency was responsible for the hypoxia‐induced increase in [Ca2+]i. We actually observed a 43% decrease in ATP concentration after 2 h hypoxia. This decrease was already significant after 30 min which thus precedes the changes in [Ca2+]i.These results show that during hypoxia, energy deficiency led to an increase in [Ca2+]i which is, however, too low to account for the loss of viability but which is within the range of concentrations observed during stimulation of endothelial cells. We propose that such increased intracellular calcium concentrations could play a role in the synthesis of mediators leading to the development of local inflammation. © 1992 Wiley‐Liss, Inc.
Modulation of mRNA levels during human keratinocyte differentiation
Authors: Younus Jawaid , Gilchrest Barbara A. 
Published: February 2005

AbstractCultures of human keratinocytes provide an excellent model system in which to study differentiation. Using the phorbol ester 12‐O‐tetradecanoyl‐phorbol 13‐acetate (TPA) and calcium, two agents known to induce keratinocyte differentiation in vitro, we examined the expression of the genes encoding c‐fos, c‐myc, and c‐jun; involucrin, a protein precursor of the keratinocyte cornified envelope; and L‐7, a ribosomal protein. Overall, at the doses studied, TPA induced a more rapid and profound differentiation than did calcium, as evaluated by culture morphology and northern blot analysis. Our studies showed a constant low level of c‐fos and c‐jun expression in unstimulated cells with no significant change after addition of either TPA or calcium except when transcript breakdown was inhibited by cycloheximide. The c‐myc proto‐oncogene, known to have a high constitutive expression in actively proliferating cells, was strongly downregulated by TPA, but calcium had no effect over a 32 hour period, consistent with the greater growth inhibition of TPA in this system. Involucrin was induced about ninefold by both TPA and calcium as early as 8 hours after stimulation, suggesting transcriptional regulation of this gene during differentiation. L‐7, recently demonstrated to be downregulated in late passage human fibroblasts in an in vitro model of senescence, was also strongly downregulated by either TPA or calcium, consistent with an interrelationship between the basic cellular processes of aging and differentiation. These finding expand our knowledge of the differentiation process in human keratinocytes. © 1992 Wiley‐Liss, Inc.
Cytokines involved in monocyte mediated tumor cell death and growth inhibition in serum‐free medium
Authors: Van Der Bosch Jürgen , Rüller Elisabeth , Ernst Martin , Schade Ulrich F. , Mathison John C. , Rüller Stephan , Schlaak Max 
Published: February 2005

AbstractIn a serum‐free culture system, the release of TNF, II‐1, II‐6, IFN‐α, and IFN‐β during interaction of elutriated human monocytes (MO) with human tumor cells (TC) was studied by ELISA‐technique. Contributions of these cytokines to inhibition of TC‐growth and to induction of TC‐death by supernatants (SU) gained from such MO/TC‐interaction cultures were investigated using affinity chromatography for removal of individual cytokines. Although the TC used are relatively insensitive to recombinant human TNF, withdrawal of TNF causes 50% to 75% reduction of SU‐induced TC‐death rates, suggesting that susceptibility to TNF is raised during MO/TC‐interaction by the other cytokines. Individual removal of other cytokines does not cause reduction of SU‐mediated TC‐death. However, combined withdrawal of II‐1 and IFN‐α/β causes in 2 of 4 TC‐lines significant reduction of TC‐death. Combined removal of TNF, IFN‐α/β, II‐1, and II‐6 leads to complete prevention of SU‐mediated growth inhibitory and lytic effects, suggesting that besides these cytokines other signals are not involved significantly. SU‐effects can be mimicked by appropriate combinations of authentic cytokines. The response of TC to SU‐or cytokine‐exposure is strikingly dependent on TC‐density, leading at subconfluent TC‐density exclusively to inhibition of growth and at postconfluent TC‐density to induction of cell death. The principal effect of SU or cytokine combinations in this context seems to be the activation of growth inhibitory signal transduction pathways leading to TC‐death in postconfluent TC‐populations exclusively if growth stimulatory pathways are activated at the same time. Mouse L cells do not follow this reaction pattern: Their death is exclusively dependent on the presence of TNF in SU and they die upon SU‐exposure at postconfluent as well as at subconfluent cell density. © 1992 Wiley‐Liss, Inc.
TGF‐beta inhibits proliferation of and promotes differentiation of human promonocytic leukemia cells
Authors: Bombara Christine , Ignotz Ronald A. 
Published: February 2005

AbstractTransforming growth factor‐beta 1 (TGF‐β1) has been implicated in a variety of responses associated with wound healing and inflammation. Thus, TGF‐β1 enhances production of several extracellular matrix proteins both in vitro and in vivo, is chemotactic for monocytes, and alters the functioning of lymphocytes. We have examined the ability of TGF‐β1 to affect the behavior of human THP‐1 promonocytic leukemia cells, a cell line with the capacity to differentiate into macrophage‐like cells. TGF‐β1 reduces the growth rate of these cells, induces morphologic changes, and promotes adherence to culture surfaces. In addition, the adherent cell population expresses high levels of esterase activity, acquires the ability to ingest latex beads, and releases elevated levels of interleukin 1. TGF‐β1‐treated cells also express elevated levels of the β2 family of integrins. Taken together, these results suggest that TGF‐β1 is capable of promoting the maturation of promonocytic cells into macrophages. This outcome has implications at wound sites where TGF‐β1 and a myriad of other factors interact with many cell types to facilitate healing. © 1992 Wiley‐Liss, Inc.
Phorbol ester‐induced promyelocytic leukemia cell adhesion to marrow stromal cells involves fibronectin specific α5β1 integrin receptors
Authors: Martin‐Thouvenin V. , Gendron M. C. , Hogervorst F. , Figdor C. G. , Lanotte M. 
Published: February 2005

AbstractThe human promyelocytic cell line NB4 exhibited a weak adhesion capacity in bone marrow‐derived stromal cells and their extracellular matrices (5–15% of adherent cells). Adhesion was enhanced by pulse‐treatment of cells with phorbolester (PMA 10−7 M). Adhesion was induced within minutes, was fibronectin‐specific, and affected up to 100% of the treated cells. This biological response to PMA resulted from the activation of protein kinase C (PKC), since PKC inhibitors (staurosporine, sphingosine, CGP 41251, and calphostin C) prevented the phenomenon. Phenotypical analysis of integrin receptor expression (particularly FN receptors VLA‐4 and VLA‐5) at the membrane of untreated or PMA‐treated cells revealed that PMA induced no significant modification of the level of expression of these receptors. However, inhibition studies carried out with anti‐VLA monoclonal antibodies demonstrated that the FN‐specific adhesion triggered by PKC involved the α5β1 FN‐specific receptors (VLA‐5) We showed that the bindings of NB4 cells to fibronectin was RGD‐dependent. PMA‐induced adhesion was not correlated to phosphorylation of the VLA‐5 receptor. These findings may partially explain the malignant behaviour of these cells: The loss of their capacity to adhere to stomal cells may arrest differentiation and explain the large number of leukemic cells in the circulation. © 1992 Wiley‐Liss, Inc.
Heparin inhibition of autonomous growth implicates amphiregulin as an autocrine growth factor for normal human mammary epithelial cells
Authors: Li Shiwei , Plowman Gregory D. , Buckley Sharon D. , Shipley Gary D. 
Published: February 2005

AbstractNormal human mammary epithelial cells (HMECs) proliferate in a serum‐free defined growth medium in the absence of epidermal growth factor (Li and Shipley, 1991). Amphiregulin (AR) is a heparin‐regulated, EGF‐like growth factor. Our observation that one strain of HMECs produce AR mRNA (Cook et al., 1991a) stimulated us to determine whether AR expression was a common phenomenon in HMECs and whether AR could act as an autocrin growth factor to support the EGF‐independent growth of these cells. In this study, we detected high levels of AR expression in four separate HMEC strains while one immortal mammary cell line (HBL‐100) and six mammary tumor‐derived cell lines had low to undetectable levels of AR. The EGF‐indendent growth of HMECs was blocked by the addition of heparin or a monoclonal anti‐RGF receptors antibody to the culture medium, implication AR as an autocrine growth mediator. This hypothesis is further supported by the fact that medium conditioned by HMECs contains secreted AR protein. A mammary tumor‐derived cell line, Hs578T, which proliferates in an EGF‐independent manner, does not express detectable levels of AR and is not growth inhibited by heparin. Examination of the same cell types for expression of transforming growth factor type‐alpha (TGF‐α) mRNA revealed coordinate expression of AR and TGF‐α in these cells. These data suggest that both AR and TGF‐α mRNA are produced in much greater abundance by normal HMECs than in tumor‐derived cells in culture, and that AR is an important autostimulatory factor for the growth of normal HMECs. © 1992 Wiley‐Liss, Inc.
Plasminogen activator inhibitor‐1 is induced in migrating endothelial cells
Authors: Pepper M. S. , Sappino A. P. , Montesano R. , Orci L. , Vassalli J.‐D. 
Published: February 2005

AbstractIt has been proposed that a finely tuned protease‐anti‐protease equilibrium must be mainted during process of cell migration in order to limit extracellular proteolysis to the close proxmity of the cell surface, and therby to prevent excessive extracellular matrix degradation. We have previously shown that urokinase‐type plasminogen activator (u‐PA) activity is induced in microvascular endothelial cells migrating from the edges of a wounded monolayer in vitro (Pepper et al., J. Cell Biol., 105:2535–2541, 1987). By Northern analysis, we now demonstrate that plasminogen activator inhibitor 1 (Pal‐1) mRNA is increased in multiple‐wounded monolayers of bovine microvascular (BME) or aortic (BAE) endothelial cells, with a maximal 7‐ and 9‐fold increase 4 h after wounding, respectively. By in situ hybridization, we demonstrate that the increase in PAI‐1 mRNA in localized to cells at the edge of a wounded BME or BAE cell monolayer. The increase in PAI‐1 mRNA observe in BME cells is independent of cell division and is inhibited by antibodies to basic fibroblast growth factor (bFGF), suggesting that PAI‐1 induction in migrating cells is mediated by the autocrine activity of bFGF. Taken together with our previous observations on the induction of u‐PA, these results support the hypothesis that the proteolytic balance in the pericellular environment of migrating cells is regulated through the concomitant production of proteases and protease inhibitors. © 1992 Wiley‐Liss, Inc.
Monoclonal antibody that recognizes the carbohydrate portion of cell adhesion molecule L1 influences calcium current in cultured neurons
Authors: Asou Hiroaki 
Published: February 2005

AbstractA monoclonal antibody (mAb), 2E12, against the neural cell adhesion molecule L1 recognized the 200 kDa component of L1. The epitope of L1 reacting with mAb 2E12 was localized in its carbohydrate chain, judging from the results of experiments on glycopeptidase F treatment. The physiological effect of adding mAbL1 (2E12) to cultured mouse dorsal root ganglion neurons was studied using patch‐clamp techniques. The binding of mAbL1 (2E12) to the neurons expressing L1 molecule induced an inward current inhibited by calcium channel blockers such as nifedipine and Lanthanum. It was also found that the mAbL1 (2E12) leads to a rise in the intracellular Ca2+ concentration ([Ca2+]i) in cultured neurons. This rise seems to be due to an influx of extracellular Ca2+, since treatment with EGTA abolished those phenomena. L‐type calcium channel blockers such as nifedipine and cadmium, as well as inward current, blocked the effect of mAbL1 (2E12). These results suggest that the carbohydrate chain of L1 glycoprotein is directly involved in the induction of calcium current, and that the L1 molecule may play a prominent role in regulation of the Ca2+ channel. © 1992 Wiley‐Liss, Inc.