bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clonal origin of murine hemopoietic colonies with apparent restriction to granuclocyte‐macrophage‐megakaryocyte (GMM) differentiation
Authors: Nakahata Tatsutoshi , Ogawa Makio 
Published: February 2005

AbstractWe characterized murine hemopoietic colonies consisting of granulocytes, macrophages, megakaryocytes, and blast cells and yet lacking erythroid elements. Mouse marrow or spleen cells were cultured in methylcellulose media in the presence of 10% (v/v) pokeweek mitogen‐stimulated spleen cell‐conditioned medium (PWM‐SCM) and 2 units/ml erythropoietin for 8 days. Granulocyte‐macrophage‐megakaryocyte (GEMM) colonies could be distinguished from granulocyte‐erythrocyte‐macrophage‐megakaryocyte (GEMM) colonies because the former lacked the typical appearance of bursts with red color. Analysis of Y‐chromosomes in mixing experiments with male and female marrow cells confirmed the clonal nature of the GMM colonies. Differential counts of GMM colonies revealed varying, but significant, numbers of blast cells in all of the day‐8 and day‐12 colonies and in seven out of ten day‐14 GMM colonies. In general, the percentages of blast cells were inversely related to the length of incubation in culture. Replating experiments confirmed the absence of late erythroid precursors such as CFU‐E and normoblasts in all of the 50 day‐8 GMM colonies. However, six out of the 50 GMM colonies contained early progenitors capable of erythroid expression, such as BFU‐E, CFU‐EM, CFU‐GEM, and CFU‐GEMM. In contrast, the three day‐14 GMM colonies which did not reveal blast cells failed to produce secondary colonies. Thus, while the progenitors for the latter colonies are restricted to only granulocyte‐macrophage‐megakaryocyte differentiation, some of the apparent GMM colonies containing blast cells may have originated in early progenitors close to pluripotent stem cells. Detailed cytological analyses and replating experiments are necessary for characterization of true differentiation potentials of mixed colonies in culture.
Clonal analysis of progenitor cell commitment to granulocyte or macrophage production
Authors: Metcalf D. , Burgess A. W. 
Published: February 2005

AbstractGranulocyte‐macrophage colony formation by C57BL bone marrow cells was initiated in agar cultures either by the granulocyte‐macrophage stimulus, GM‐CSF, or by the predominantly macrophage stimulus, M‐CSF. After 24 hours, paired daughter cells of granulocyte‐macrophage colony‐forming cells (GM‐CFC) were separated by micromanipulation and one cultured in GM‐CSF, the other in M‐CSF. From the differentiation pattern of the resulting colonies, irreversible commitment of some cells occurred during the first 24 hours and completion of the first cell division. A similar result was obtained using granddaughter cells present after 24 hours of incubation. However, when intact developing day 2 and days 3 clones were cross‐transferred to GM‐CSF or M‐CSF recipient cultures, irreversible commitment was more obvious. Most M‐CSF‐initiated clones exhibited irreversible commitment to macrophage formation in GM‐CSF cultures and a high proportion of GM‐CSF‐initiated clones continued to produce granulocyte progeny after transfer to M‐CSF.The results indicated that GM‐CSF and M‐CSF can irreversibly commit the progeny of GM‐CFC respectively to granulocyte or macrophage production. While for some GM‐CFC this occurs within 24 hours and one cell division, for many cells, the process is slower and requires an incubation period of up to 48 hours and/or several cell divisions.Calculations from the data indicated that two‐thirds of GM‐CFC in adult C57BL marrow are biresponsive and respond to stimulation both by GM‐CSF and M‐CSF.
Parallel changes in protein synthesis and messenger RNA content in growing and resting epithelial cells of Xenopus laevis
Authors: Budorick Nancy E. , Miller Leo 
Published: February 2005

AbstractThe regulation of cell growth can be achieved at many levels but ultimately the regulatory factors must alter protein synthesis since growing cells always exhibit an increased rate of protein synthesis compared to resting cells. Some studies using growing and nongrowing mammalian cells have shown that the rate of protein synthesis compared to resting cells. Some studies using growing and nongrowing mammalian cells have shown that the rate of protein synthesis is directly dependent on mRNA content. Other studies have shown that growing and resting cells have similar amounts of mRNA and that protein synthesis is regulated by the proportion of mRNA in polysomes. We have analyzed mRNA content in growing and resting epithelial cells of Xenopus laevis. Quantitation of poly(A)+ mRNA by uniform labeling with 3H‐uridine and by 3H‐poly(U)hybridization demonstrated a direct relationship between mRNA content and the relative rate of protein synthesis in growing and resting cells. Likewise, after serum stimulation of resting cells the increase in mRNA content closely paralleled the increase in protein synthesis. Our results suggest that control of protein synthesis in growing and nongrowing cells is exerted before the translational level.
The increase in hormone‐stimulated adenylate cyclase activity following rous sarcoma virus transformation
Authors: Howard Randall F. , Friis Robert R. , Sheppard J. R. , Glossmann Hartmut 
Published: February 2005

AbstractRous sarcoma virus (RSV)‐infected chicken embryo cells were used to study the effect of viral transformation on the hormone‐stimulated synthesis of cyclic AMP. Transformation by RSV in response to the β‐adrenergic agonist isoproterenol as compared to untransformed cells. This enhancement was observed in both intact cells and in membranes prepared from these cells. The inclusion of guanosine 5'‐0‐(3‐thiotriphosphate), a nonhydrolyzable analogue of GTP, in assays of adenylate cyclase activity did not abolish the quantitative differences between the transformed and normal cell membranes. Infection of cells by Rous‐associated virus, which lacks the oncogene src, did not induce this hyperresponsiveness thus indicating the probable involvement of the src gene product in this phenomenon. The duration of the isoproterenol‐induced cyclic AMP elevation was longer in the transformed than in the untransformed cells; transformed cells, unlike untransformed cells, required at least 120 min before full desensitization became established. Membranes prepared from transformed cells specifically bound more than 5 times the quantity of the β;‐adrenergic radiolabeled antagonist (‐)3H‐dihydroalprenolol and 125I‐iodocyanopindolol compared to the untransformed cell membranes. Thus, it appears that major differences between the transformed and normal phenotypes reside in the concentration of membrane β‐adrenergic receptors and the inability of RSV‐transformed cells to self‐limit their response to specific external stimuli.
Contact‐stimulated proliferation of cultured mouse epidermal cells by 3T3 feeder layers: Inhibition of proliferation by 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA)
Authors: Miller Don R. , Hamby Kathy M. , Slaga Thomas J. 
Published: February 2005

AbstractMouse epidermal cells can be subcultured at 31°C onto an irradiated BALB/c 3T3 clone A31 feeder layer. A31 cells (supposedly derived from embryonic fibroblasts) were found to be specifically required for the optimal production of keratinizing epidermal colonies in secondary culture. This effect was not transmitted through the medium nor by the culture surface, since A31 cells plated on one end of a flask did not stimulate epidermal cell proliferation at the other end, even if the other end had previously held A31 cells. Epidermal cell contact with metabolizing A31 cells was probably necessary for the effect; fixed or freeze‐thawed A31 cells were ineffective. The tumor promoter 12‐O‐tetradecanoylphorbol‐13‐acetate, recently shown to interfere with contact‐mediated transfer of label (metabolic cooperation) between Swiss 3T3 cells and cells of an established epidermal line in vitro, also blocked epidermal colony formation. The A31‐epidermal cell interaction is apparently not a typical mesenchymal‐epithelial interaction, since the basement membrane would prevent this contact in intact skin.
Signals causing change in morphological phenotype, growth mode, and gene expression of vascular endothelial cells
Authors: McAuslan B. R. , Hannan G. N. , Reilly W. 
Published: February 2005

AbstractComparison of three different lines of bovine aortal endothelial cells provides a clear demonstration of reversible morphologic phenotype coincidental with change in expression and growth mode. These phenotypic forms can be externally controlled so that cells may exist either in an epithelioid contact‐inhibitable state or as a fibroblastoid non‐contact‐inhibitable state.Clonal cell line N (normal) shows a strong tendency to maintain the epithelioid phenotype. Clonal cell line Sp (sprout) can readily and reversibly adopt the epithelioid or fibroblastoid phenotype. A factor in normal serum is responsible for maintaining the cells in the epithelioid phenotype. This factor could be a growth factor since several polypeptide growth factors are shown to drive cells from the fibroblastoid phenotype to the epithelioid phenotype within 11 hours. This growth factor‐induced change is not mediated through induced DNA synthesis. Clonal cell line V (variant) normally maintains the fibroblastoid phenotype but can be directed to the epithelioid phenotype provided cells are on an appropriate collagenous matrix.Associated with these changes in morphological phenotype are depression of the expression of the pro α2 chain of collagen type I which may be characteristic of the contact‐inhibited state and of an 80,000 mol wt polypeptide synthesized only by cells in the fibroblastoid phenotype. An endothelial cell collagen ECl (mol wt 177,000) was synthesized by all cell lines regardless of phenotype whereas a suspected breakdown product EC3 (mol wt 100,000) was found only in the epithelioid phenotype. Other differences and similarities between cell lines include expression of a 135,000 mol wt glycoprotein GP (V and N), the procollagen of collagen type III (N) of fibronectin (N, V, Sp), and of the pro α1 chain of collagen type I (Sp, V). The characteristic expression of each line and its response to signals controlling morphologic phenotype impinges on the question of whether there exist several distinct types of vascular endothelial cells with different functional potentials controlled by extracellular signals.
Topography of the predifferentiation GD growth arrest state relative to other growth arrest states in the G1 phase of the cell cycle
Authors: Wille John J. , Scott Robert E. 
Published: February 2005

AbstractThe differentiation of 3T3 T proadipocytes is preceded by growth arrest at a state in the G1 phase of the cell cycle (GD) which is distinct from other G1 growth arrest states including those induced by serum deprivation (GS) or nutrient deprivation (GN) (Scott et al., 1982). We now report that the GD, GS, and GN arrest states are also distinct in their topography in G1. This conclusion was derived from kinetic studies which measured the time required for cells arrested at various G1 states to synthesize DNA and from studies on the ability of GD‐, GS‐, or GN‐arrested cells to be converted from one arrest state to another in the absence of DNA synthesis. The results suggest that relative to the start of the G1 phase of the cell cycle, the following arrest state topography exists: GD, GS, GN.
Concentration of mast‐cell progenitors in bone marrow, spleen, and blood of mice determined by limiting dilution analysis
Authors: Sonoda Takashi , Ohno Takako , Kitamura Yukihiko 
Published: February 2005

AbstractWhen hematopoietic cells of congenic +/+ mice were injected into the skin of genetically mast‐cell‐depleted (WB × C57BL/6)F1‐W/Wv mice, mast cells appeared at the injection site. The donor origin of developing mast cells was confirmed by using granules of C57BL/6‐bgl/bgl mice as a marker. When the number of injected cells was decreased, the proportion of injection sites at which mast cells did not appear increased according to the expected frequency of null response in a Poisson distribution. Therefore, such proportions were used to calculate the concentration of mast‐cell precursors in the bone marrow, spleen, and peripheral blood. The relative concentration of mast‐cell precursors in these tissues was similar to that of spleen‐colony‐forming cells. The present method seems useful as a semiquantitative in vivo assay for a population of progenitor cells which are committed to differentiate into mast cells.
Role of stimulation of arachidonic acid release in the proliferative response of 3T3 mouse fibroblasts to platelet‐derived growth factor
Authors: Shier W. T. , Durkin J. P. 
Published: February 2005

AbstractHuman platelet‐derived growth factor (PDGF) stimulates release of arachidonic acid from cellular phospholipids, synthesis and release of prostaglandins from the cell, and initiation of DNA synthesis in cultures of 3T3 Swiss mouse fibroblasts at similar concentrations with four independent preparations representing a million‐fold range of purification. Stimulation of archidonic acid and prostaglandin release is an early event (beginning within minutes) in the response to PDGF treatment. Incubating cells with PDGF at 4°C followed by washing leads to activation of archidonic acid release on warming the cells to 37°C, consistent with binding of the factor to the cell surface. PDGF‐stimulated arachidonic acid release, prostaglandin release, and initiation of DNA synthesis are all inhibited by phenylglyoxal at similar concentrations. These results suggest that activation of arachidonic acid release from phospholipids plays an essential role in the mechanism by which PDGF stimulates the initiation of DNA synthesis in 3T3 cells. The stimulation of initiation of DNA synthesis by PDGF does not appear to be mediated by the synthesis of prostaglandins or other known arachidonic acid metabolites because neither indomethacin (a fatty acid cyclooxygenase inhibitor) nor phenidone (a lipoxygenase inhibitor) inhibit initiation of DNA synthesis at concentrations which inhibit arachidonic acid metabolism. Although the activation of arachidonic acid release by PDGF is a calcium‐dependent process, a simple calcium flux appears unimportant to the mechanism of activation. Evidence was also obtained against an involvement of sodium fluxes or proteolytic activity in the mechanism of stimulating arachidonic acid release by PDGF or serum.
Distinct bone marrow precursors for mononuclear phagocytes expressing high and low 5′ ‐nucleotidase activity
Authors: Bursuker Isia , Goldman Rachel 
Published: February 2005

AbstractUsing a cytochemical assay we were able to show that the peritoneal macrophage population of normal nontreated mice (resident peritoneal macrophages) exhibits a heterogeneity with regard to the expression of the activity of the ecto‐enzyme 5′‐nucleotidase (5′‐N). About 75% of the macrophages express high enzymic activity whereas the remaining 25% express low 5′‐N activity. Macrophages accumulating in the peritoneum as a result of an inflammatory response are predominantly of the low activity type. In vitro activation of resident peritoneal macrophages by lymphokines does not result in a decrease in the number of macrophages expressing high enzymic activity though the level of the enzymic activity of these cells is reduced by about 36%. Bone marrow derived mononuclear phagocyte colonies developing in vitro, under liquid culture conditions, from bone marrows of normal mice can be divided into three types with respect to their expression of 5′‐N activity: (1) high activity colonies–relatively small colonies in which all the cells express high 5′‐N activity (about 20% of the colonies); (2) low activity colonies – relatively large colonies in which all the cells express low 5′‐N activity (about 70% of the colonies); and (3) mixed colonies–relatively large colonies in which all the cells express low enzymic activity except for about 8% of cells located at the periphery of the colonies which express high enzymic activity (about 10% of the colonies). During an inflammatory response the frequency of the high activity colonies is significantly reduced. Our results provide evidence for distinct bone marrow precursors for mononuclear phagocytes expressing high and low 5′‐N activity and suggest that (1) the resident macrophages derive from a subpopulation of bone marrow precursor cells developing in vitro into high 5′‐N activity mononuclear phagocytes, and (2) during an inflammatory response there is a preferential expansion of clones of the low enzymic activity phenotype.
Synergistic stimulation of DNA synthesis by cyclic AMP derivatives and growth factors in mouse 3T3 cells
Authors: Rozengurt Enrique 
Published: February 2005

AbstractAddition of the cAMP derivatives butcAMP or 8BrcAMP to quiescent cultures of Swiss 3T3 causes synergistic stimulation of DNA synthesis with insulin, phorbol esters, vasopressin, epidermal growth factor, or fetal bovine serum (2–5%). In the presence of insulin, 8BrcAMP, and butcAMP stimulate [3H]‐thymidine incorporation into acid‐precipitable material in a dose‐dependent manner. The effect of these agents in specific since 8Br5´AMP, 5′AMP, butyrate, or 8BrcGMP fail to stimulate DNA synthesis under identical experimental conditions. Furthermore, the mitogenic effects of the cAMP derivatives were markedly potentiated by 1‐methyl‐3‐isobutyl xanthine and 4‐(3‐butoxy‐4‐methoxy benzyl)‐2‐imidazolidine, both of which are potent inhibitors of cyclic nucleotide phosphodiesterase activity. The growth‐promoting effects of the cAMP derivatives were demonstrated by [3H]‐thymidine incorporation (either by scintillation counting or by autoradiography), by flow cytofluorometric analysis, and by increase in cell number. When quiescent Swiss 3T3 cells were exposed to butcAMP and insulin, DNA synthesis began after a lag of 17 h. The result of sequential additions of cAMP derivatives and insulin to quiescent 3T3 cells suggest that these agents must act simulaneously in G0/G1 to stimulate entry into DNA synthesis in these cells. The findings support the proposition that an increase in cellular levels of cAMP (but not cGMP) acts as a mitogenic stimulus for confluent and quiescent Swiss 3T3 cells.
Cyclic AMP stimulation of Na‐K pump activity in quiescent Swiss 3T3 cells
Authors: Paris Sonia , Rozengurt Enrique 
Published: February 2005

AbstractRecently, we have found that an increase in the intracellular level of cAMP acts as a mitogenic signal for Swiss 3T3 cells (Rozengurt et al., Proc. Natl. Acad. Sci. USA, 78:4392, 1981). The results presented in this paper demonstrate that addition of cAMP‐elevating agents to confluent and quiescent cultures of Swiss 3T3 causes a marked increase in the rate of 86Rb+ uptake but has no effect on the rate of cation efflux. The stimulation of ion uptake is mediated by the Na‐K pump as shown by the ouabain sensitivity of the 86Rb+ fluxes. The increase in Na‐K pump activity occurs whether cAMP is generated endogenously by stimulation of adenylate cyclase activity by cholera toxin, adenosine agonists, or PGE1 or added exogenously as 8BrcAMP. The stimulatory effect of these compounds on 86Rb+ uptake is potentiated by inhibitors of cyclic nucleotide phosphodiesterase activity. Cholera toxin stimulates the Na‐K pump in a dose‐dependent manner; half‐maximal effect is achieved at 0.7 ng/ml.The stimulation of ouabain‐sensitive 86Rb+ uptake by cAMP‐elevating agents reaches a maximum after 2‐3 h of incubation. This contrasts with the rapid (within minutes) stimulation of the Na‐K pump caused by serum and other mitogenic agents. Further, cAMP‐elevating agents fail to increase in Na+ influx, under identical experimental conditions. These findings suggest that the stimulation of Na‐K pump activity caused by increased cAMP levels contrasts mechanistically with the rapid control of pump activity by serum which is primarily mediated by increased Na+ entry into the cells.
β‐Galactosidase—An indicator of the maturational stage of mouse and human mononuclear phagocytes
Authors: Brusuker Isia , Rhodes Joan M. , Goldman Rachel 
Published: February 2005

AbstractResident, elicited, and activated mouse peritoneal macrophages exhibit a differential expression of the activity of the enzyme b̃‐galactosidase; freshly harvested resident macrophages express a remarkably high activity whereas the latter two populations are almost void of enzymic activity. During in vitro cultivation there is an enhancement in the level of the enzyme in the three populations, and a significant proportion of both thioglycollate‐elicited and Corynebacterium parvum‐activated macrophages acquire b̃‐galactosidase activity. Cells within in vitro differentiated bone marrow‐derived mononuclear phagocyte colonies are heterogeneous with respect to expression of b̃‐galactosidase activity. The percentage of cells expressing medium to intense enzymic activity is augmented with time in culture. Essentially the same pattern is observed in colonies differentiated from bone marrow of mice bearing acute or chronic inflammation. Freshly isolated human peripheral blood monocytes are essentially void of detectable b̃‐galactosidase activity. Eighty to ninety percent of the monocytes acquire medium to intense activity during a 7‐day cultivation period. The data support the suggestion that b̃‐galactosidase expression in mononuclear phagocytes is a correlate of their maturational stage both in vivo and in vitro and does not reflect the state of elicitation or activation of these cells.
Developmental restriction of mobility of concanavalin a receptors
Authors: Lipke Peter N. , Lilien Jack 
Published: February 2005

AbstractTrypsinized cells from embryonic chick neural retina redistributed concanavalin A receptors to patches and caps. Between 12 and 16 days of development, the ability to redistribute concanavalin A receptors declined. This restriction in mobility of the receptors was accompanied by changes in susceptibility to the capping‐inhibitory drugs colchicine and cytochalasin B.
Oxygen‐stimulated cytochrome oxidase assembly in hepatocyte monolayer cultures
Authors: Hare James F. , Hodges Randall 
Published: February 2005

AbstractIsolated rat liver hepatocytes exhibited a twofold to threefold increase in both specific cytochrome oxidase activity and heme a concentration during their first 24 h in monolayer culture. Other mitochondrial respiratory enzyme activity did not increase over this same period. Decreasing the oxygen content of the gas phase to 5% of ambient eliminated the stimulation in heme a content without having an effect on cell protein synthesis or viability. These results indicate that oxygen concentration can effect the level of cytochrome oxidase (heme a) in these differentiated cells. The effect of oxygen may be on the translation or assembly of subunits, synthesis of heme, or incorporation of heme into holoenzyme. Oxygen stimulation of cytochrome oxidase content was not accompanied by increased incorporation of pulsed radiolabelled methionine into immunoprecipitated holoenzyme subunits. Moreover, chloramphenicol, a translation inhibitor of three mitochondrially synthesized cytochrome oxidase subunits, did not diminish the increase in heme a seen over the first 24 h of culture. These latter results suggest that the increasing enzyme content is not due to stimulated translation.