bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lineage commitment in human hemopoiesis involves asymmetric cell division of multipotent progenitors and does not appear to be influenced by cytokines
Authors: Mayani Hector , Dragowska Wieslawa , Lansdorp Peter M. 
Published: February 2005

AbstractDifferent models have been proposed to explain lineage commitment in hemopoiesis. Some suggest that lineage commitment occurs in a stochastic manner without the direct influence of extracellular factors; others postulate that cytokines determine whether multipotent cells will become erythroid or granulocyte/macrophage progenitors. In the present study, the patterns of proliferation and differentiation of individually sorted human cord blood‐derived primitive hemopoietic cells (highly enriched for multipotent progenitors) were analyzed in a serum‐free culture system supplemented with different cytokine combinations. In a first set of experiments, the response of individual cells to different cytokine combinations was compared, whereas in a second set of experiments, single cells were allowed to undergo one division after which the two daughter cells were physically separated and cultured in either the same or different cytokine combinations. Proliferation of progenitor cells was absolutely dependent on cytokines, and the combination of mast cell growth factor plus interleukin 6 was sufficient to induce mitosis. When cytokine combinations favoring erythropoiesis and/or myelopoiesis were added to the cultures, a more vigorous proliferative response of the sorted primitive progenitors was observed. Interestingly, the relative proportions of granulocyte/macrophage, erythroid, and multipotent progenitors remained more or less the same regardless of the cytokine combination used, indicating a permissive rather than an instructive role for cytokines in hemopoietic differentiation. Asymmetric cell divisions, defined as a division that yields two daughter cells with distinct functional properties, were observed in 3–17% of the progenitor cells capable of forming colonies under our experimental conditions. In the rest, symmetric divisions involving multipotent and lineage‐committed progenitors were observed. The results of this study demonstrate that the asymmetric cell divisions that occur in the early stages of hemopoiesis at the level of multipotent progenitors cannot be skewed by the addition of specific cytokine combinations. These findings support the hypothesis that lineage commitment in hemopoiesis occurs in a stochastic manner by mechanisms that remain to be elucidated. © 1993 Wiley‐Liss, Inc.
Disparate modulation of plasma membrane protein lateral mobility by various cell permeabilizing agents
Authors: Feder Tony J. , Chang En‐Yuh , Holowka David , Webb Watt W. 
Published: February 2005

AbstractThe mobility of a cell surface protein on cells osmotically swollen by treatment with several different cell permeabilizing agents retains specific restraints despite detachment of the plasma membrane from the cortical cytoskeleton. Fluorescence photobleaching recovery experiments indicate that the lateral diffusion constants of immunoglobulin E (IgE)‐receptor complexes on the surface of rat basophilic leukemia cells increase 2–5 × following permeabilization with streptolysin O or digitonin, with little change in their mobile fractions. Swelling by hypo‐osmotic treatment in water enhances lateral diffusion of IgE‐receptor complexes and raises the mobile fractions to near 100%. In contrast, swelling by treatment with filipin arrests lateral diffusion, although rotational mobility remains unhindered. Lateral mobility of a fluorescent lipid analogue remains unchanged under these conditions. Crosslinking by anti‐IgE antibodies redistributes the IgE‐receptor complexes into large patches on untreated cells and on cells swollen by permeabilization with streptolysin O or digitonin, but rot on cells swollen by treatment with filipin. The results indicate a diversity of effects of the various permeabilizing agents on the mobility of membrane proteins. In particular, treatment with filipin appears to reorganize the plasma membrane into a network of fluid domains on a scale smaller than the bleaching spot size used (∼1.5 μm). © 1994 Wiley‐Liss, Inc.
Slowed receptor trafficking in mutant CHO lines of the end1 and end2 complementation groups
Authors: Johnson Lester S. , Presley John F. , Park Juliet C. , McGraw Timothy E. 
Published: February 2005

AbstractA mutant Chinese hamster ovary cell line with nonconditional kinetic defects in receptor internalization and recycling was isolated, based on selection for resistance to a transferrin‐diphtheria toxin conjugate and screening for aberrant receptor trafficking. The 12‐4 cell line internalizes transferrin at ∼75% of the parental rate and recyles transferrin back to the cell surface at ∼55% of the parental rate. Internalization of low density lipoprotein is also reduced to ∼70% of the parental cell rate, demonstrating that the mutant phenotype affects the trafficking of multiple receptors. Characterization of somatic cell hybrids indicated that the 12‐4 phenotype is recessive, and complementation analysis determined that the 12‐4 cell line is a member of the End2 complementation group. End2 mutants have previously been described as defective in endosomal acidification but have not been known to be defective in receptor trafficking. We have found similar defects in another End2 mutant cell line, suggesting that slowed receptor trafficking is characteristic of End2 mutants. Interestingly, transferrin receptor recycling and internalization are also slowed in another complementation group of mutants, End1, that is also defective in endosomal acidification. This study demonstrates altered receptor trafficking in End1 and End2 cell lines, a novel aspect of the mutant phenotypes. These findings provide evidence, based on a cellular genetic approach, that proper endosome acidification is necessary for maintenance of normal receptor recycling. © 1994 Wiley‐Liss, Inc.
Bumetanide and furosemide inhibited vascular endothelial cell proliferation
Authors: Panet Rivka , Markus Miriam , Atlan Henri 
Published: February 2005

AbstractIn this study, we examined the role of the bumetanide‐sensitive Na+/K+/Cl–cotransport in the mitogenic signal of vascular endothelial cell proliferation. The activity of the Na+/K+/Cl– cotransport is dramatically decreased in quiescent subconfluent cells, as compared to subconfluent cells growing in the presence of FGF. The Na+/K+/Cl– cotransport activity of quiescent subconfluent cultures deprived of FGF decreased to 6%, whereas that of quiescent cells grown to confluency was reduced to only 33% of the activity of subconfluent cells growing in the presence of FGF. The basal low activity of Na+/K+/Cl– cotransport in the quiescent subconfluent vascular endothelial cells was dramatically stimulated by FGF. In order to explore the role of the Na+/K+/Cl– cotransport in the mitogenic signal of the endothelial cells, the effect of two specific inhibitors of the cotransport ‐furosemide and ‐bumetanide was tested on cell proliferation induced by FGF. Bumetanide and furosemide inhibited synchronized cell proliferation measured by direct counting of cells and by DNA synthesis. Inhibition by fuorsemide and bumetanide was reversible; removal of these compounds completely released the cells to proliferate. These results indicate that the effect of these drugs is specific and is not due to an indirect toxic effect. This study clearly demonstrates that the FGF‐induced activation of the Na+/K+/Cl– cotransport plays a role in the mitogenic signal pathway of vascular endothelial cells. © 1994 Wiley‐Liss, Inc.
Characterization of 57 kDa statin as a true marker for growth arrest in tissue by its disappearance from regenerating liver
Authors: Sandig Martin , Bissonnette Robert , Liu Catherine H. L. , Tomaszewski George , Wang Eugenia 
Published: February 2005

AbstractStatin, a 57 kDa nuclear protein, is lost from quiescent fibroblasts in culture when they are induced to enter the cell cycle by feeding with growth factors, or by removal of contact inhibition. In order to investigate changes in statin expression during the transition from a quiescent to a cycling state in situ, we performed 70% partial hepatectomy on rats and analyzed the regenerating liver by immunofluorescence microscopy with antistatin monoclonal antibodies (S44 mAb), and by immunoblotting of liver proteins in cytoplasmic and enriched nuclear/cytoskeletal fractions. Western blot analysis showed that rat hepatocytes in situ contain a nuclear 57 kDa form of statin, as seen in cultured fibroblasts; however additional S44‐immunoreactive polypeptides with molecular weights of 53 and 110 kDa are also present in both cytoplasmic and nuclear/cytoskeletal fractions. Immunofluo‐rescence microscopy indicates that the proportion of S44‐positive hepatocyte nuclei drops to ∼60% within 24 hours after hepatectomy, a time period when re‐entry of hepatocytes into the cell cycle is first observed. On Western blots of hepatocyte nuclear/cytoskeletal proteins obtained 24 hours after hepatectomy, the 57 kDa form of statin is markedly reduced. These results suggest that, although in liver the S44 antibody recognizes three proteins (53 kDa, 57 kDa, and 110 kDa), the 57 kDa in intact liver, similar to cultured fibroblasts, is the only polypeptide recognized by the statin antibody that disappears when hepatocytes are induced to re‐enter the cell cycle from a quiescent state. © 1994 Wiley‐Liss, Inc.
Effect of ion composition on the changes in membrane potential induced with several stimuli in rat mast cells
Authors: Cabado Ana G. , Vieytes Mercedes R. , Botana Luis M. 
Published: February 2005

AbstractWe studied, in different ionic conditions, the effect of various agents on the membrane potential of rat peritoneal mast cells using the fluorescent probe bisoxonol. Ouabain and ionophore A23187 lead to a fast depolarization of the plasma membrane of mast cells, while compound 48/80 and thapsigargin induced membrane hyperpolarization, which was more pronounced in the case of compound 48/80. When using compound 48/80, the amount of gramicidin necessary to depolarize the cells was twice the amount required in resting cells, which indicates that compound 48/80 increases considerably the activity of the Na+/K+ pump. On the other hand, the ionophore A23187 elicited a clear depolarization which was oblated in the absence of intracellular calcium. The increase in the osmolarity of the medium causes a depolarization in the plasma membrane of mast cells. Hypertonicity‐stimulated depolarization is inhibited by removing sodium and potassium. © 1994 Wiley‐Liss, Inc.
Glutamic acid potentiates hepatocyte response to mitogens in primary culture
Authors: Hasegawa Kaoru , Miyata Yasuji , Carr Brian I. 
Published: February 2005

AbstractAdult rat hepatocytes in primary culture responded to epidermal growth factor (EGF) by increased DNA synthesis. When hepatocytes were cultured in Leibovitz L‐15 medium, their response to EGF was low compared with that in Williams' medium E or Koga's medium L. Furthermore, female rat hepatocytes showed almost no response to the mitogenic action of EGF compared with male rat hepatocytes in L‐15 medium. Addition of glutamic acid (1–20 μM) to EGF‐containing L‐15 medium not only enhanced DNA synthesis > tenfold in both male and female hepatocytes, but eliminated the sex differences in DNA synthesis. Aspartic acid, glutamine, or ornithine at 20 mM did not replace the glutamic acid effect on DNA synthesis. Proline also enhanced EGF‐induced DNA synthesis, although it was less effective than glutamic acid. Therefore, this effect may be specific to a high concentrations of glutamic acid. Glutamic acid by itself did not stimulate DNA synthesis at any concentrations tested. In the presence of glutamic acid, EGF showed a dose‐dependent (0.5–20 ng/ml) stimulation of DNA synthesis with a maximal effect at 10 ng/ml. Almost the same effect was obtained with transforming growth factor alpha (0.5–20 ng/ml). Glutamic acid also induced an expansion of the mitogenic action of angiotensin II. Since glutamic acid did not affect [125I]EGF binding to hepatocytes or its processing, the effect may occur internal to the receptor. These results suggest that glutamic acid modulates the sensitivity of the hepatocyte response to mitogens © 1994 Wiley‐Liss, Inc.
Cross‐talk of parathyroid hormone‐responsive dual signal transduction systems in osteoblastic osteosarcoma cells: Its role in PTH‐induced homologous desensitization of intracellular calcium response
Authors: Sugimoto Toshitsugu , Ikeda Kazuto , Kano Junichi , Yamaguchi Toru , Fukase Masaaki , Chihara Kazuo 
Published: February 2005

AbstractThe present study was designed to characterize the cross‐talk of parathyroid hormone (PTH)‐responsive dual signal transduction systems (cAMP‐dependent protein kinase (PKA) and calcium/protein kinase C [PKC]) and its participation in PTH‐induced homologous desensitization of intracellular calcium ([Ca2+]i) in osteoblastic UMR‐106 cells. Although our recent study revealed that prolonged (more than 2 h) pretreatment with PKC‐activating phorbol ester, phorbol 12‐myristate 13‐acetate (PMA) significantly decreased the PTH‐stimulated cAMP production, pretreatment with PMA (10−7 and 10−6 M) but not 10−6 M 4alphaphorbol 12,13‐didecanoate (PDD), incapable of activating PKC for 30 min significantly augmented 10−7 M hPTH‐(1‐34)‐stimulated cAMP production. H‐7 (50 uM), a PKC inhibitor, significantly antagonized this PMA‐induced effect. Pretreatment with 10−6 M PMA for 30 min did not affect PTH receptor binding but significantly augmented a cAMP responsiveness to 10−5 M forskolin and 1 ug/ml cholera toxin. Pertussis toxin (0.5 ug/ml) did not affect the PMA‐induced augmentation of the PTH‐stimulated cAMP production. PTH caused a complete homologous desensitization of [Ca2+]i response within 30 min. Pretreatment with 10−4 M dibutyryl cAMP for 30 min and 6 h significantly reduced and completely blocked the PTH‐induced increase in [Ca2+]i, respectively. Pretreatment with 10−4 M Sp‐cAMPS, a direct PKA activator, for 30 min completely blocked the PTH‐induced increase in [Ca2+]i. Rp‐cAMPS (10−4 M), an antagonist of PKA, slightly but significantly antagonized the PTH‐induced homologous desensitization of [Ca2+]i response. The present study indicates that the time of exposure to PKC activation is a critical determinant in modulating the cAMP system, while PKA activation counterregulatorily acts on the [Ca2+]i system, and that PKA activation is linked to the PTH‐induced homologous desensitization of [Ca2+]i response. © 1994 Wiley‐Liss, Inc.
Vanadate reduces sodium‐dependent glucose transport and increases glycolytic activity in LLC‐PK1 epithelia
Authors: Madsen Karen L. , Porter Valerie M. , Fedorak Richard N. 
Published: February 2005

AbstractThe effect of vanadate pentoxide on apical sodium‐dependent glucose transport in LLC‐PK1 epithelia was examined. Epithelia grown in the presence or absence of 1 μM vanadate formed confluent monolayers and exhibited no differences in DNA, protein, or ultrastructure. Vanadate‐supplemented epithelia demonstrated a lower steady‐state α‐methyl‐D‐glucopyranoside (AMG) concentrating capacity and a twofold reduction in apical AMG uptake Jmax. This decreased AMG transport occurred as a consequence of a reduction in the number of transport carriers and was not associated with a change in the sodium electrochemical gradient. The vanadate‐induced reduction in apical glucose carrier functional activity and expression was accompanied by a stimulation of intracellular glycolytic flux activity, as evidenced by increased glucose consumption, lactate production, PFK‐1 activity, and intracellular ATP. There was no difference in intracellular cAMP levels between vanadate‐supplemented and non‐supplemented epithelia. These results demonstrate an association between stimulation of glycolytic pathway activity and an adaptive response in the form of a reduction in the function and expression of the sodium‐dependent apical glucose transporter in LLC‐PK1 epithelia. © 1994 Wiley‐Liss, Inc.
Effect of staurosporine on MOLT‐4 cell progression through G2 and on cytokinesis
Authors: Traganos Frank , Gong Jianping , Ardelt Barbara , Darzynkiewicz Zbigniew 
Published: February 2005

AbstractStaurosporine (SSP) is an inhibitor of a variety of protein kinases with an especially high affinity towards protein kinase C. Whereas SSP has been shown to halt the cell cycle progression of various normal, nontransformed cell types in G1, most virus transformed or tumor cells are unaffected in G1 but arrest in G2 phase. SSP has also been observed to increase the appearance of cells with higher DNA content, suggestive of endoreduplication, in cultures of tumor cells. Using multivariate flow cytometry (DNA content vs. expression of cyclin B, nucleolar p120 protein, or protein reactive with Ki‐67 antibody) which makes it possible to discriminate cells with identical DNA content but at different phases of the cycle, we have studied the cell cycle progression of human lymphocytic leukemic MOLT‐4 cells in the presence of 0.1 μM SSP.MOLT‐4 cells did not arrest in G1 or G2 phase in the presence of the inhibitor. Rather, they failed to undergo cytokinesis, entering G1 phase at higher DNA ploidy (tetraploidy; G1T), and then progressed through ST (rereplication) into G2T and MT. The rates of entrance to G2 and G2T were essentially identical, indicating that the rates of cell progression through S and ST as well as through G2 and G2T, respectively, were similar. Cells entrance to mitosis and mitotic chromatin condensation were also similar at the diploid and tetraploid DNA content level and were unaffected by 0.1 μM SSP. No evidence of growth imbalance (altered protein or RNA to DNA ratio) was observed in the case of tetraploid cells. The data show that, in the case of MOLT‐4 cells, all events associated with the chromosome or DNA cycle were unaffected by SSP; the only target of the inhibitor appears to be kinase(s) controlling cytokinesis. © 1994 Wiley‐Liss, Inc.
Recombinant human bone morphogenetic protein‐2 enhances expression of interleukin‐6 and transforming growth factor‐β1 genes in normal human osteoblast‐like cells
Authors: Zheng Ming H. , Wood David J. , Wysocki Stan , Papadimitriou John M. , Wang Elizabet H. A. 
Published: February 2005

AbstractThe process of recombinant human bone morphogenetic protein‐2 (rhBMP‐2)‐induced endochondral ossification involves (1) the proliferation and differentiation of mesenchymal cells into chondroblasts and osteoblasts; (2) the production and maturation of cartilage and bone matrix; and (3) the differentiation of circulating osteoclast precursor cells into osteoclasts. Currently the molecular mechanisms of these complex sequential events are unknown. It seemed reasonable to us to assume that communication between cells through soluble mediators during bone induction by rhBMP‐2 may play an important role in the sequential differentiation of chondroblasts, osteoblasts, and osteoclasts. We have therefore used a human osteoblast‐like initial transfectant cell line (HOBIT) to study the effect of rhBMP‐2 on gene expression of interleukin‐6 (IL‐6) and transforming growth factor‐β1 (TGF‐β1), both of which affect osteogenesis and ostoeclastogenesis. Our results have demonstrated that rhBMP‐2 acts on HOBIT cells to stimulate expression of IL‐6 and TGF‐β1 genes and the production of IL‐6. Enhancement of gene expression of IL‐6 and TGF‐β1 by rhBMP‐2 was both sensitive (half maximal effect at approximately 10 ng/ml) and potent (maximum induction was approximately four and threefold greater than controls, respectively). Time course studies showed that the induction of TGF‐β1 and IL‐6 mRNA occurs within short periods—4 and 8 hours after exposure to rhBMP‐2, respectively. Interestingly, these effects, however, were not accompanied by the mitogenic action of rhBMP‐2. It suggests that rhBMP‐2 enhances IL‐6 and TGF‐β1 production during osteogenesis and at least in part mediates the complex sequential differentiation of chondroblasts, osteoblasts, and osteoclasts during rhBMP‐2‐induced endochondral ossification. © 1994 wiley‐Liss, Inc.
Failure of infinite life span human cells from different immortality complementation groups to yield finite life span hybrids
Authors: Ryan P. Ann , Maher Veronica M. , Justin McCormick J. 
Published: February 2005

AbstractThe observation that fusion of infinite life span cells with finite life span cells produces hybrid cells with finite life spans led to the conclusion that an infinite life span in culture is a recessive trait resulting from loss of the function of a gene or genes that contribute to an active program for cellular senescence. Furthermore, finding that certain pairs of infinite life span cells, when fused to one another, can complement each other to yield finite life span hybrids allowed 30 infinite life span cell lines to be assigned to four immortality complementation groups (Pereira‐Smith and Smith, 1988, Proc. Natl. Acad. Sci. U.S.A., 85:6042). In the present study, we fused a chromosomally stable, near diploid, morphologically normal, infinite life span cell strain, designated MSU‐1.1, with its normal, finite life span, precursor cell strain and obtained finite life span hybrids, as expected if infinite life span in culture is a recessive trait. However, 14 of the 14 hybrids from our fusions of MSU‐1.1 cells with representative cell lines from each of the four immortality complementation groups, and 38 of the 39 hybrids from our fusions of infinite life span cells that have been reported to complement each other, failed to exhibit finite life spans. This result suggests that infinite life span cells cannot complement each other to yield finite life span hybrids. In examining this unexpected result, we obtained evidence that long‐term dual drug selection can be deleterious to hybrid cells even though they carry resistance markers for both drugs, indicating that the cell death of such hybrids observed in other studies may have resulted from the cytotoxic effect of long‐term drug selection, rather than from senescence. © 1994 wiley‐Liss, Inc.
IL‐1α and TNFα act synergistically to stimulate production of myeloid colony‐stimulating factors by cultured human bone marrow stromal cells and cloned stromal cell strains
Authors: Caldwell Jerry , Emerson Stephen G. 
Published: February 2005

AbstractHuman bone marrow stromal cells repond to stimulation by the monokines IL‐1 and TNF by producing colony‐stimulating factors such as GM‐CSF and G‐CSF. In this study we show that IL‐1α and TNFα act synergistically to stimulate GM‐CSF and G‐CSF production by cultured marrow stromal cells. We further show that IL‐1α and TNFα synergistically stimulate production of GM‐CSF and G‐CSF by a clonal stroma‐derived cell strain. Although IL‐1 and TNF share many of the same biological activities, we show that IL‐1α and TNFα have an unequal ability to induce myeloid‐CSF production by both cultures, with IL‐1α being the more potent inducer. We found that induction by IL‐1α and TNFα was independent of cell proliferation. The effect of IL‐1α and TNFα on production of the two myeloid‐CSFs by the clonal cells was significantly greater than the unfractionated passaged stromal cultures, having the greater effect on G‐CSF production. The clonally derived stromal cells constitutively produced colony‐stimulating activity, in particular GM‐CSF, at levels easily detected by ELISA. These findings show that, in addition to the overlapping and additive activities of IL‐1α and TNFα, they can interact synergistically. Our findings further suggest that a small subpopulation of stroma cells may be the major producer of G‐CSF in the marrow microenvironment during immune response. © 1994 wiley‐Liss, Inc.