bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of the mitogenic effect of fetuin preparations on arterial smooth muscle cells: The role of contaminant platelet‐derived growth factor
Authors: Libby Peter , Raines Elaine W. , Cullinane Paula M. , Ross Russell 
Published: May 2005

AbstractFetuin, a major protein of fetal calf serum, partially purified by the method of Pedersen, stimulated growth of aortic smooth muscle cells. More highly purified fetuin preparations stimulated growth less than Pedersen fetuin, as previously described for other cell types, suggesting that this activity is due to a contaminant. Recently bovine alpha2‐macroglobulin or “Embryonin” has been proposed as the mitogenic component of crude fetuin preparations. We found that active fetuin preparations did contain alpha2‐macroglobulin that stimulated smooth muscle cell growth. However, alpha2‐macroglobulin purified directly from platelet‐poor bovine plasma or fetuin purified from Pedersen fetuin by gel filtration lacked appreciable mitogenic effect on smooth muscle cells. Since alpha2‐macroglobulin can bind platelet‐derived growth factor (PDGF), and since highly acidic fetuin might bind the very basic PDGF molecule non‐specifically, we measured the PDGF content of various fetuin preparations and found a good correlation between the PDGF content and mitogenic activity. Gel filtration experiments demonstrated that in Pedersen fetuin PDGF occurred both free, and in association with alpha2‐macroglobulin. We conclude that the principal mitogenic component for smooth muscle cells in crude fetuin preparations is PDGF, since purified bovine alpha2‐macroglobulin or fetuin do not appreciably affect growth of these cells. These results help to resolve a long‐standing controversy regarding the nutrition of cultured cells. In addition, we suggest that before alpha2‐macroglobulin or “Embryonin” is accepted as a bona fide growth factor for a given cell type, the role of contamination with PDGF should be assessed.
A stochastic model for mast cell proliferation in culture
Authors: Pharr Pamela N. , Nedelman Jerry , Downs Heather P. , Ogawa Makio , Gross Alan J. 
Published: May 2005

AbstractA birth‐death model was developed for the proliferation of mast cells. According to the model, each secondary mast cell colony starts with one proliferative cell. At each generation each cell chooses among three possibilities: (1) division into two proliferative cells; (2) division into two non‐proliferative cells; or (3) disappearance. At each step, a non‐proliferative cell either does nothing or disappears. A computer simulation of this model could be fitted reasonably well to our data for the size distributions of secondary mast cell colonies recorded after different culture periods. Our model predicts that proliferative cells comprise a larger fraction of the colony in large secondary colonies than in small ones. This prediction was successfully tested by examination of tertiary colony formation. This is a general model for cell proliferation that may be applicable to other types of cells.
Differential effects of the tumor promoter phorbol‐12‐myristate‐13‐acetate on the morphological and biochemical differentiation of N‐18 mouse neuroblastoma cells
Authors: Liu Alice Y.‐C. , Chen Kuang Yu 
Published: May 2005

AbstractThe phorbol ester tumor promoter phorbol‐12‐myristate‐13‐acetate (PMA) was found to have differential inhibitory effects on the expression of morphological and biochemical differentiation of N‐18 mouse neuroblastoma cells. PMA completely inhibited neurite extension and associated growth characteristics and partially inhibited the increased expression of R1 cAMP‐binding protein; PMA had no effect on the induction of acetylcholinesterase activity in cells prompted to differentiate either by treatment with 1 mM dibutyryl cAMP or by serum deprivation. 4‐α‐Phorbol‐12, 13‐didecanoate, an inactive analogue of phorbol ester tumor promoter, was without effect. The implications of these findings concerning the mechanism of action of phorbol ester tumor promoters in the control of cell differentiation are discussed.
Alterations in superoxide dismutase, glutathione, and peroxides in the plasmodial slime mold Physarum polycephalum during differentiation
Authors: Allen R. G. , Newton R. K. , Sohal R. S. , Shipley G. L. , Nations C. 
Published: May 2005

AbstractChanges in the level of antioxidant defenses and the concentration of free radical by‐products were examined in differentiating (M3cVII and LU897 × LU863), non‐differentiating (LU887 × LU897), and heterokaryon microplasmodia of the slime mold Physarum polycephalum during spherulation in salts‐only medium. As differentiation proceeded, superoxide dismutase activity increased by as much as 46 fold; glutathione concentration and the rate of oxygen consumption decreased; cyanide‐resistant respiration, hydrogen peroxide, and organic peroxide concentrations increased. The non‐differentiating culture failed to exhibit any of these changes. A heterokaryon obtained by the fusion of differentiating and non‐differentiating strains was observed to differentiate at a very retarded rate and to exhibit the changes observed in the spherulating strains at a correspondingly slower rate. These observations suggest that a free radical mechanism may be involved in the differentiation of Physarum microplasmodia into spherules.
Modulation of fibroblast‐induced clot retraction by calcium channel blocking drugs and the monoclonal antibody ALB6
Authors: Azzarone Bruno , Krief Patricia , Soria Jeannette , Boucheix Claude 
Published: May 2005

AbstractSuspensions of living human fibroblast induce fibrin clot retractile activity (FCR). The efficiency is dependent on the growth phase; it is maximal during active growth and reduced in post‐confluent cultures. In contrast human osteosarcoma cells constantly exhibit very low FCR efficiency. Two different calcium channel‐blocking drugs Diltiazem and Verapamil inhibit, depending on the concentrations employed, FCR, and spreading within the clots of the normal cells. Intermediate FCR levels are associated with intermediate degrees of spreading. A similar dose dependent inhibition is also obtained by treating the normal cells with the calmodulin inhibitor trifluoperazine (TFP). On the other hand, treatment of the normal cells with the monoclonal antibody ALB6 which is directed at the human leukocyte differentiation antigen CD9 (p24) causes a significant increase in the FCR efficiency in post‐confluent normal cells, but it has no effect on the Te85 osteosarcoma cells. Moreover ALB6 IgG reverses the FCR inhibitory effect of the calcium‐channel blocking drugs but not that of TFP. This means that the ALB6 IgG target on the cellular membrane is probably the same as that of the two drugs and that ALB6 IgG is active in the regulation of the calcium flux which controls fibrin clot retractile activity of normal human fibroblasts.
A colony‐stimulating factor for neutrophil granulocytes: A marked increase of its production by the addition of sodium butyrate and lipopolysaccharide in serum‐free culture of RSP‐2 · P3 Cells
Authors: Tsuneoka K. , Shikita M. 
Published: May 2005

AbstractSodium butyrate, lithium acetate, and hydroxyurea given to serum‐free culture of RSP‐2 · P3 cells notably reduced the rate of cell proliferation but markedly enhanced the production of such a colony‐stimulating factor (CSF) as one that stimulated predominantly neutrophilic granulocyte colony formation in mouse bone marrow cell cultures (Tsuneoka and Shikita, 1984). On the other hand, the production of macrophage CSF was not increased in the butyrate‐treated RSP‐2 · 3 cells. Butyrate also failed to enhance either macrophage CSF or neutrophil CSF production in L · P3 (mouse fibroblast line), Huk‐1 · P3 (human kidney cell line) or Nil2C2 (hamster embryo fibroblast line) cells. The addition of bacterial lipopolysaccharide (LPS) together with butyrate resulted in further pronounced enhancement of the neutrophil CSF production in RSP‐2 · P3 cells, while the cells did not develop tolerance against LPS upon repeated challenge. The yield of neutrophil CSF was thus increased by about 45 times that of the control during continuous culture for 12 days. Large‐scale culture of the cells under these conditions must be an excellent source of a CSF for neutrophil granulocytes.
Flow cytometric analysis of tetanus toxin binding to neuroblastoma cells
Authors: Notter Mary F. D. , Leary James F. 
Published: May 2005

AbstractA neuroblastoma cell line was assessed for its capacity to bind tetanus toxin (TT) by using immunofluorescence and flow cytometry to analyze cells on a single cell basis. A clone of Neuro 2a, N2AB‐1, was shown to bind variable amounts of TT per cell and this binding could be saturated by increasing doses of the toxin. Toxin binding was specific for neuronal cells, as the non‐neuronal cell line, C6 glioma, bound negligible amounts of toxin. Variability of immunofluorescence staining was due in part to the increase in size of N2AB‐1 cells as they progress through the cell cycle as measured by cell surface densities of toxin binding and DNA levels by propidium iodide (Pl) staining. When N2AB‐1 cells were treated with exogenous gangliosides for 24 h, cells were induced to sprout neurites and cell growth was inhibited. Analysis of DNA histograms indicated that ganglioside treatment caused more cells to appear in G0G1 of the cell cycle than that seen for untreated controls. Upon cytometric analysis of TT binding to ganglioside treated cells, it was apparent that treatment stimulated all cells to bind TT in larger amounts per cell than that seen with untreated N2AB‐1 cells. These data suggest that TT binding and, therefore, toxin receptors are constant in density throughout the cell cycle of these neuroblastoma cells and that exogenous gangliosides can cause differentiation followed by increased toxin binding.
Growth kinetics as a function of ploidy in diploid, tetraploid, and octaploid smooth muscle cells derived from the normal rat aorta
Authors: Rosen Eliot M. , Goldberg Itzhak D. , Shapiro Howard M. , Zoller Lawrence C. , Myrick Kyl V. , Levenson Stephen E. , Halpin Patricia A. 
Published: May 2005

AbstractThe smooth muscle cell population in major arteries of humans and experimental animals is heterogeneous with regard tocellular DNA content. A proportion of cells has polyploid DNA content and this proportion increases with normal aging and with hypertension. We have isolated pure populations of rat aortic smooth muscle cells containing 2C, 4C, and 8C DNA content by cloning of cultures of cells previously subjected to flow cytometric cell sorting. Karyologic analysis of these clonal populations revealed them to be pure diploid, tetraploid, and octaploid populations, respectively, containing 2N (= 42), 4N, and 8N chromosomes. Cell attachment area and nuclear size appeared to increase with the level of ploidy. Studies of the proliferative characteristics of the cells revealed that the growth rate and ultimate cell densities achieved decreased as the ploidy level increased. The intrinsic cellular radiosensitivity of these clones did not vary with ploidy. Increased smooth muscle cell ploidy is, therefore, associated with a decreased rate of proliferation. The emergence of smooth muscle cells with polyploid DNA content under normal and pathologic conditios is probably due to mitotic polyploidization without net cell proliferation and may be related to the need for expression of differentiated functions.
Commitment to differentiation of human promyelocytic leukemia cells (HL60): An all‐or‐none event preceded by reversible losses of self‐renewal potential
Authors: von Melchner Harald , Höffken Klaus 
Published: May 2005

AbstractA method for clonal analysis has been developed which allows the characterization of the number and type of progeny cells produced by each single cell arising during clonal evolution. The method is based on a symmetry of self‐renewal exhibited by sister cells of the human promyelocytic leukemia cell line ‐HL60‐. This permits the use of one of the sister cells to measure the potential for self renewal of the other.Using a system of sequential daughter cell transfers in semisolid medium, we have analysed self‐renewal and differentiation in individual clones exposed to all‐trans retinoic acid or dimethylsulfoxide (DMSO). We find that in clones exposed to chemical inducers of differentiation commitment occurs as an all‐or‐none event which is preceded by coordinated but reversible losses of self‐renewal potential.It is concluded that the differentiation pathway of HL60 cells has two distinct portions. These are, first, a predeterministic portion, reflected by coordinated but reversible losses of self‐renewal potential, and second, a deterministic portion, reflected by irreversible phenotypic differentiation.
Glycosaminoglycan production in cultures of early and late passage human endothelial cells: The influence of an anionic endothelial cell growth factor and the extracellular matrix
Authors: Gordon Portia B. , Conn Greg , Hatcher Victor B. 
Published: May 2005

AbstractAn endothelial cell (EC) growth factor isolated from bovine brain stimulates in vitro growth of human umbilical vein endothelial cells, and permits long term serial propagation. In the presence of increasing concentrations of EC growth factor, confluent cultures of early (CPDL ⩽ 20) and late (CPDL > 20) passage human endothelial cells exhibit an increased incorporation of 3H‐glucosamine and Na235SO4 into the glycosaminoglycans (GAG), hyaluronic acid, chondroitin, chondroitin‐4‐sulfate, dermatan‐4‐sulfate, and chondroitin‐6‐sulfate. An increase in both labelled sulfated and nonsulfated GAG was observed in the cytosol, membrane, secreted and extracellular matrix fractions. In contrast, endothelial cells grown in the presence of EC growth factor contained decreased amounts of labelled heparan sulfate than cells grown without EC growth factor. Confluent cultures of early passage cells had significantly more labelled GAG but significantly less heparan sulfate than cultures of late passage cells on a per cell basis. Extracellular matrix from early passage cells contained about two‐ to seven‐fold more labelled GAG than extracellular matrix from late passage cells, but only about half as much labelled heparan sulfate. Cell adhesion was enhanced when cells were grown in the presence of EC growth factor as compared to adhesion of cells grown without EC growth factor. Conversely, trypsin‐mediated detachment of cells grown in the presence of growth factor was inhibited as compared to detachment of cells grown in medium without EC growth factor. The composition of the extracellular matrix influenced incorporation of labelled GAG into extracellular matrix. Early passage cells grown to confluence on a matrix from late passage cells incorporated significantly less labelled GAG into extracellular matrix than when grown to confluence on matrix from early passage cells. Incorporation of labelled GAG into extracellular matrix was significantly higher when late passage cells were grown on matrix from late passage cells. We conclude that (1) EC growth factor selectively stimulates incorporation of isotopic precursors into GAG in cultures of early and late passage endothelial cells but inhibits incorporation of radiolabel into heparan sulfate; (2) early passage cells contain more GAG but less heparan sulfate than late passage cells; (3) extracellular matrix controls the amount of GAG and heparan sulfate incorporated into matrix; (4) cells grown in the presence of EC growth factor are more adhesive to the substratum and more resistant to detachment by proteolytic enzymes than cells grown in medium without EC growth factor.
Transferrin receptor regulation is coupled to intracellular ferritin in proliferating and differentiating HL60 leukemia cells
Authors: Rhyner Kaspar , Taetle Raymond , Bering Harriet , To Dong 
Published: May 2005

AbstractCultured myeloid leukemia cells display transferrin receptors but decrease receptor display after differentiation induction or accumulation of intracellular iron. To determine whether regulation of transferrin receptors and ferritin were linked under these disparate conditions, serum‐free and fetal bovine serum (FBS) cultures of HL60 promyelocytic leukemia cells were used to investigate relationships between transferrin receptor display and intracellular ferritin. Using 125I‐ transferrin binding and immunofluorescence staining for transferrin receptors, HL60 cells cultured in serum‐free, transferrin‐free medium expressed fewer transferrin receptors and contained increased ferritin when compared to cells cultured with FBS or transferrin supplemented, serum‐free medium. When placed in medium containing transferrin, cells previously grown in transferrin‐free medium rapidly re‐expressed transferrin receptors and decreased their ferritin content. HL60 cells induced to differentiate into granuiocytes or macrophages also decreased transferrin receptor display and increased their ferritin content. Transferrin receptor display and ferritin content in both proliferating and differentiating myeloid leukemia cells are inversely related and their regulation is closely linked. Regulation of transferrin receptor display and ferritin synthesis may be important events regulating myeloid cell growth and differentiation.
The edge‐transitive but not vertex‐transitive cubic graph on 112 vertices
Authors: Conder Marston , Malnič Aleksander , Marušič Dragan , Pisanski Tomaž , Potočnik Primož 
Published: May 2005

AbstractA detailed description is given of a recently discovered edge‐transitive but not vertex‐transitive trivalent graph on 112 vertices, which turns out to be the third smallest example of such a semisymmetric cubic graph. This graph has been called the Ljubljana graph by the first author, although it is believed that its existence may have been known by R. M. Foster. With the help of some advanced theory of covering graphs, various properties of this graph are analyzed, including a connection with the Heawood graph via ideals over polynomial rings. © 2005 Wiley Periodicals, Inc.
Synchronized temperature/density programming in capillary supercritical fluid chromatography
Authors: Later D. W. , Campbell E. R. , Richter B. E. 
Published: May 2005

AbstractThe theoretical and practical implications of simultaneous temperature/pressure and synchronized density/temperature programming are considered. Examples are shown for separations of dimethylpolysiloxanes where these techniques provide superior separation over their analogous isothermal programming methods.
Static coating of phenyl and biphenyl polysiloxane stationary phases on small‐diameter capillary columns
Authors: Woolley C. L. , Tarbet B. J. , Markides K. E. , Bradshaw J. S. , Lee M. L. , Bartle K. D. 
Published: May 2005

AbstractStatic coating of phenyl and biphenyl polysiloxane stationary phases on 50 μm i.d. open tubular capillaries was studied. The influence of coating solvents and coating temperatures on the viscosities and surface tensions of the polymer stationary phases and their coating solutions was determined. A measure of the Rayleigh instability paralled the observed coating efficiencies.
“Groove‐injection” as a novel method for sub‐microliter (nanoliter) injections in liquid chromatography using a conventional multi‐port valve
Authors: Berry V. , Lawson K. 
Published: May 2005

AbstractIn liquid chromatography with “low‐dispersion methods”, there is an increasing need to reproducibly inject nanoliter sample volumes. Low‐dispersion methods produce very narrow peaks because of short column length, narrow column bore, small particle packing, low particle surface area, open tubular configuration, or combinations of these parameters.This paper describes a new injector method, the “groove‐injector” which involves simple plumbing changes for use of a conventional multi‐port valve (8‐ports or more) to inject sample volumes approximating a single groove in such a valve (e.g 30 nanoliters with aceptable reproducibility, ca. 8% RSD). In addition, by changing a resistor, volumes between 30, and over 2,000 nanoliters (nearly two orders of magnitude) can be injected with reproducibilities generally below 2% RSD. Different samples can be injected by using an autosampler.Compared to commonly used 4‐port valves for nanoliter injections, multi‐port valves have a number of advantages. Multiport valves generally are more commonly available and they are a better financial investment because of their versatility for column switching, sample enrichment, or variable volume injections. Previously, submicroliter (nanoliter) injections have not been possible with multi‐port valves in as direct and simple a manner as described here.
Computer‐assisted chromatogram evaluation in dual capillary gas chromatography
Authors: Neu H. J. , Larsen M. , Panzel H. , Merz W. 
Published: May 2005

AbstractGas‐chromatographic analysis of complex mixtures is simplified enormously by the use of the simultaneous dual capillary technique. The advantages over a single‐column system are that the components are more reliably identified and quantified. After integration has taken place, the data from both capillaries are cor‐related with the aid of a computer program whose principles are described.
Solvent modulation: An accurately modeled method for controlling solute retention in liquid chromatography
Authors: Wahl J. H. , Enke C. G. , McGuffin V. L. 
Published: May 2005

AbstractAn innovative solvent delivery method termed solvent modulation has been developed to control solute retention in liquid chromatography. Solvent modulation is the technique whereby individual solvent zones are introduced onto the chromatographic column in a known random orrepeating sequence. Because the solvent zones are of constant composition and are spatially separated from one another, solute retention is controlled independently in each zone. Hence, the overall retention of a solute is a time‐weighted average of the capacity factors in the solvent zones it has encountered. Solvent modulation offers a simple, versatile, and accurately modeled means to control and predict solute retention in liquid chromatography.
High sensitivity laser induced fluorescence detection in capillary zone electrophoresis
Authors: Nickerson B. , Jorgenson J. W. 
Published: May 2005

AbstractLaser induced fluorescence is used for the detection of labeled amino acids. A preliminary comparison is made of three fluorescence pre‐column labeling reagents, ortho‐phthaldialdehyde, naphthalene dicarboxaldehyde, and fluorescein isothiocyanate, and data on phenylalanine detection limits are given.
Selectivity enhancement of a metal‐sensitive flame ionization detector for capillary gas chromatography
Authors: Gallagher M. M. , Hill Herbert H. 
Published: May 2005

AbstractA novel modification of a hydrogen‐atmosphere flamo ionization detector (HAFID) is presented which attenuates response to hydrocarbon compounds, significantly enhancing selectivity towards organometallic compounds by more than an order of magnitude. Chromatograms of an organometallic compound test mixture and regular leaded gasoline are presented to depict the specificity of the response.