bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human endothelial cell cultures: Phenotypic modulation by leukocyte interleukins
Authors: Montesano R. , Orci L. , Vassalli P. 
Published: February 2005

AbstractWe report here that soluble factors from activated mononuclear leukocytes have a dramatic effect on cultured endothelial cells. While human umbilical vein endothelial cells grown under standard conditions show a polygonal, epitheliallike morphology, cells exposed to culture media conditioned by lectin‐activated human mononuclear leukocytes become extremely elongated and/or send out numerous cytoplasmic processes, assuming a dendritic configuration. This effect cannot be mimicked by exogenous cyclic AMP, is reversible upon interruption of the treatment, and appears specific for endothelial cells, since it has not been observed so far with other cell types. The shape changes are accompanied by a reorganization of the endothelial cell cytoskeleton: actin microfilament bundles tend to be disposed in parallel arrays, while intermediate filaments and microtubules penetrate up to the extremity of the cytoplasmic processes. Colchicine prevents endothelial cell elongation but only slightly impairs the formation of lateral cell processes (“dendritic configuration”). Purified interleukins were tested for their ability to induce these changes of cell shape. Escherichia coli‐recombinant human interleukin 2 had no effect, and γ‐interferon only a slight effect on endothelial cell morphology. Interleukin 1 induced moderate cell elongation, while combined treatment with both interleukin 1 and γ‐interferon resulted in shape changes indistinguishable from those elicited by supernatants of activated mononuclear leukocytes. The possible relevance of the observed endothelial cell changes to the reported angiogenic activity of mononuclear cell products is discussed.
Modulation of the platelet‐derived growth factor induced replicative response
Authors: Scher C. D. , Whipple A. P. , Singh J. P. , Pledger W. J. 
Published: February 2005

AbstractQuiescent cultures of density arrested BALB/c‐3T3 cells have been sensitized to the growth stimulatory action of the platelet‐derived growth factor (PDGF). Sensitization was achieved by depriving the cultures of PDGF prior to growth stimulation and was noted after transfer of cultures from medium supplemented with 10% serum to medium containing either an equivalent concentration of platelet‐poor plasma or a low concentration (0.5%) of serum. Sensitized cultures required less pure PDGF for growth stimulation than non‐sensitized ones. In addition such cultures required less mitogen to synthesize a PDGF modulated major excreted protein (MEP). The mechanism of sensitization was investigated. Sensitized cultures did not bind more PDGF than non‐sensitized ones. Rather, sensitization appeared to result from the loss of cells that occurred when cultures were deprived of PDGF. Such a loss increased the amount of PDGF available per cell, causing a higher percentage of cells to enter the S phase. Similarly, the amount of PDGF per cell regulated MEP synthesis. Furthermore, in non‐sensitized cultures (containing the same number of cells), the absolute quantity rather than the concentration of PDGF regulated DNA synthesis. It appears that the amount of PDGF per cell modulates mitogenesis.
Kinetics of long‐term (72 hr) calcium content during mitogen activation of cultured human T lymphocytes
Authors: Wolff C. H. J. , Åkerman K. E. O. , Andersson L. C. 
Published: February 2005

AbstractIn vitro stimulation of human blood lymphocytes with mitogen resulted in an increased intracellular content of Ca2+ per unit cell volume. This increase in Ca2+ content of lectin‐activated cells reached a maximum after 24 hr of culture and thereafter slowly declined. Brief treatment of cells at 24 hr of culture with the Ca2+ ionophore A23187 in combination with EGTA resulted in a larger release of Ca2+ from cells in mitogen‐stimulated cultures than from cells in control cultures. This indicates that the Ca2+ is accumulated intracellularly but is readily exchangeable. At 24 hr of culture the increase in cellular Ca2+ correlated well with the proliferative response as measured by 3H‐thymidine incorporation. Ca2+ influx at 24 and 48 hr of culture was markedly enhanced in the mitogenically stimulated cells as compared either to cells cultured for 1 and 72 hr or cells cultured without mitogen.
Cell volume regulation of cerebrovascular endothelium in vitro
Authors: Kempski O. , Spatz M. , Valet G. , Baethmann A. 
Published: February 2005

AbstractRegulation of cell volume as a fundamental cellular function of high biological priority was studied in cultured cerebrovascular endothelium. The use of a multiparameter flow cytometric system allowed simultaneous measurements of cell volume, viability, and membrane potential or intracellular pH. Endothelium, the cellular constituent of the blood‐brain barrier (BBB), swells immediately on exposure to low osmolality. This is associated with membrane depolarization and a fall of intracellular pH. Within 30–60 min, cell volume and membrane potential recover completely, although the extracellular osmolality is kept low. Intracellular pH does not normalize fully. Measurements of intracellular K+ and Na+ concentrations reveal their involvement in the regulatory process. The findings strongly suggest that the cerebrovascular endothelium has a highly effective built‐in capacity for homeostatic control essential for normal BBB function.
Endogenous metabolism by sperm in response to altered cellular ATP requirements
Authors: Inskeep Philip B. , Hammerstedt Roy H. 
Published: February 2005

AbstractA quantitative description of the relative importance of endogenous metabolism to overall ATP production has not been established for mammalian cells. We report herein results of experiments using sperm (selected because of their simple metabolic potential and absence of biosynthetic pathways) and calorimetry (chosen because it serves as a general monitor of metabolism) to assess the importance of endogenous metabolism to total ATP synthesis under several incubation conditions. In experiments in which sperm were incubated at different temperatures (20°C, 25°C, 30°C or 35°C) and with different substrates (glucose, fructose, lactate, or β‐hydroxbutyrate), endogenous metabolism occurred at a constant rate regardless of the rate of ATP turnover in the cells or the nature of the exogenous substrate available to them. Sperm incubated at 35°C with glycolyzable substrates synthesized more ATP (9 μmol ATP·h−1/108 cells) than did sperm incubated with the non‐glycolyzable substrate, lactate (6.2 μmol ATP·h−1/108 cells). To investigate this substrate‐related difference in the rate of ATP synthesis, the motility of sperm incubated at 35°C with glucose or with lactate was determined. The velocities of the sperm incubated with either substrate were identical, indicating that the rates of ATP consumption for support of motility were identical. Most of the additional ATP synthesized by cells with glycolyzable substrates was consumed in the process of substrate cycling of the metabolic intermediates of glucose.
The effects of osmotic stress on human platelets
Authors: Armitage W. J. , Parmar N. , Hunt C. J. 
Published: February 2005

AbstractThe effect of osmotic stress on human platelets was investigated at 0, 25, and 37°C. The osmolality of the suspending plasma was decreased by adding water or increased by adding sodium chloride or sucrose. After 5 min, isotonicity was restored by dilution with an excess of isotonic phosphate‐buffered saline. After centrifugation, the platelets were resuspended in autologous plasma and then incubated for 1 hr at 37°C before assaying the active transport of 5‐hydroxytryptamine (5‐HT) and the hypotonic stress response. Anisosmotic conditions had a greater effect on the extent of volume reversal in the hypotonic stress test than on 5‐HT uptake. At 25°C, only moderate degrees of hypotonicity (0.25 osmol/kg) or hypertonicity (0.59 osmol/kg) were sufficient to depress the hypotonic stress response. In general, platelets tolerated departures from isotonic conditions better at 0°C than at the higher temperatures. Furthermore, at 0 and 25°C approximately equiosmolal concentrations of sucrose and sodium chloride depressed the hypotonic stress response to similar extents, but at 37°C high osmolalities (> 2 osmol/kg) were tolerated better when the additive was sucrose than when it was sodium chloride. Platelets shrank when subjected to hyperosmotic conditions, but their discoid shape and the peripheral band of microtubules were maintained.
Stimulation of bumetanide‐sensitive K+ transport in Swiss 3T3 fibroblasts by serum and mitogenic hormones
Authors: Amsler Kurt , Donahue Jeremiah J. , Slayman Carolyn W. , Adelberg Edward A. 
Published: February 2005

AbstractRapidly growing Swiss 3T3 fibroblasts possess a bumetanide‐sensitive K+ transport system that is dependent on both Na+ and Cl− ions; a smaller bumetanide‐insensitive component of K+ transport is also present. In cells brought to the quiescent state by 8–11 days of incubation without a medium change, the bumetanide‐sensitive rate of transport was reduced by 63%; the bumetanide‐insensitive rate did not change. Removal of dialyzed fetal calf serum from the uptake medium resulted in a substantial reduction in bumetanide‐sensitive uptake in both rapidly growing cells (33% reduction) and quiescent cells (68% reduction) but had no effect on bumetanide‐insensitive uptake. Insulin was almost as effective as dialyzed fetal calf serum in stimulating bumetanide‐sensitive uptake; insulin was maximally stimulatory at 2.5 μg/ml. The combination of insulin, epidermal growth factor, and arginine‐vasopressin was maximally effective in stimulating both bumetanide‐sensitive K+ uptake and 3H‐thymidine incorporation in quiescent cells; bumetanide, however, did not interfere with the hormonal stimulation of DNA synthesis. Thus, the bumetanide‐sensitive K+ transport system is not necessary for such stimulation to occur. Furthermore, concentrations of hormones which stimulated significant levels of DNA synthesis produced no elevation in the intracellular concentration of K+. We conclude that the bumetanide‐sensitive pathway of K+ transport is modulated by serum and by mitogenic hormones, but does not play a role in the stimulation of DNA synthesis by these factors.
Characterization of the Na+/H+ exchanger in human epidermoid carcinoma A431 vesicles
Authors: Mancuso David , Glaser Luis 
Published: February 2005

AbstractA previous report from this laboratory (Rothenberg et al., 1983a) demonstrated the presence of an Na+/H+ exchanger in human epidermoid carcinoma A431 cells. We now characterize surface‐derived membrane vesicles from this cell line which contain a functional Na+/H+ exchanger. The Na+/H+ exchanger in A431 vesicles shares a number of characteristics in common with previously described Na+/H+ exchangers including the following: (1) Na+ uptake is stimulated by an outward‐directed pH gradient and inhibited by an inward‐directed pH gradient. (2) Na+ uptake is inhibited by amiloride and its analogs and their relative effectiveness is similar in vesicles and A431 cells. (3) The Na+/H+ exchanger uses Na+ or Li+ as a substrate but not K+ or Cs+. (4) H+ efflux is stimulated by an inward‐directed Na+ gradient and inhibited by the amiloride analog 5‐N‐dimethylamiloride. The Na+/H+ exchanger in these membrane vesicles is activated allosterically by low intravesicular pH. The apparent pKa of the activating site is 6.4–6.6, characteristic of the NA+/H+ exchanger before activation by mitogens.
Regulation of deoxyglucose uptake by adrenocorticotropic hormone in cultured neurons
Authors: Daval Jean‐Luc , Anglard Patrick , Gerard Marie‐José , Vincendon Guy , Louis Jean‐Claude 
Published: February 2005

AbstractThe influence of ACTH and some of its N‐terminal related peptides was investigated on the uptake of (3H)‐2‐deoxy‐D‐glucose in pure cultures of neurons from chick embryo cerebral hemispheres. ACTH influences deoxyglucose uptake in a time and dose‐dependent fashion. The stimulation of deoxyglucose uptake is observed after a delay of 6–8 h and requires active protein synthesis. ACTH does not affect deoxyglucose in non‐neuronal cells (astroglial cells, hepatocytes, myoblasts, fibroblasts). The effect of various peptide hormones, neuropeptides and growth factors, active in the central nervous system or other tissues, has also been examined. None of these were able to stimulate deoxyglucose uptake, suggesting that the regulation of hexose uptake in neurons is specific for the ACTH‐related peptides.
Characterization of a BALB/c 3T3 preadipose cell mutant with altered Na+K+Cl− contransport activity
Authors: Sussman Ilene , O'Brien Thomas G. 
Published: February 2005

AbstractA BALB/c 3T3 cell mutant (3T3‐E12) was isolated by its ability to survive at a low extracellular K+ concentration (0.14 mM). The growth rate of mutant cells was less dependent on external K+ than parental cells. Analysis of potassium transport revealed that 3T3‐E12 cells have a decreased activity of the furosemide‐sensitive Na+K+Cl− contrasport system, both in the efflux and influx modes. This is shown to be a result of a decrease in the apparent affinity of the transport system for K+ and Na+, but not Cl−. Upon exposure to the phorbol ester 12‐0‐tetradecanoyl‐phorbol‐13‐acetate (TPA), BALB/c 3T3 cells exhibited a maximal volume decrease of 20%, while mutant cells shrunk by only 7%, suggesting that regulation of cell volume, at least after exposure to a tumor promoter, is impaired in mutant cells compared to parental 3T3 cells.
The essential role of L‐glutamine in lymphocyte differentiation in vitro
Authors: Crawford Jeffrey , Cohen Harvey Jay 
Published: February 2005

AbstractThe biochemistry of human B lymphocyte differentiation to plasma cells is incompletely understood. L‐glutamine appears to be required for both lymphoblastic transformation and plasma cell formation in pokeweed‐mitogenstimulated human peripheral blood mononuclear cell cultures. Cells cultured with pokeweed mitogen in glutamine‐deficient RPMI‐1640 with 10% heat‐inactivated and dialyzed fetal bovine serum were unable to incorporate 3H‐thymidine or undergo morphologic lymphoblastic transformation assessed at 72 hours. However, 3H‐thymidine incorporation could be maximally restored with as little as 0.08 mM L‐glutamine or by using nondialyzed heat‐inactivated fetal bovine serum, containing approximately .1 mM L‐glutamine. In subsequent cultures, using glutamine‐deficient RPMI‐1640 with 10% nondialyzed heat‐inactivated fetal bovine serum, lymphoblastic transformation was equivalent with or without additional L‐glutamine supplementation. However, only cultures with 2 mM L‐glutamine supplementation underwent plasma cell differentiation as assessed by cytoplasmic staining with fluorescein‐conjugated anti‐immunoglobulin. When the kinetics of cellular immunoglobulin synthesis and secretion were analyzed by 3H‐ leucine incorporation into immunoglobulin, synthesis was 2–5 fold greater, and secretion 3–10‐fold greater in cell cultures with 2 mM L‐glutamine supplementation. By electron microscopy, only the glutamine‐supplemented cells showed development of rough endoplasmic reticulum consistent with active immunoglobulin production. L‐glutamine supplementation had no apparent effect on cell recovery, viability, % B cells, % T cells, % monocytes, or % helper and suppressor T cells. Thus, L‐glutamine is essential for both lymphoblastic transformation and plasma cell differentiation. Future investigation of the selective nutritional requirements of cultured cells should yield further insights into the biochemical control of immune cell differentiation and function.
Binding of 125I‐labeled granulocyte colony‐stimulating factor to normal murine hemopoietic cells
Authors: Nicola N. A. , Metcalf D. 
Published: February 2005

AbstractThe binding of granulocyte colony‐stimulating factor (G‐CSF) to murine bone marrow cells was investigated using a radioiodinated derivative of high specific radioactivity which retaine full biological activity. The binding was time‐and temperature‐dependent, saturable and highly specific. The apparent dissociation constant for the reaction was 60–80 pM at 37°C and 90–110 pM at 4°C, similar to that found for the binding of G‐CSF to murine leukemic cells (WEHI‐3B D+) and significantly higher than the concentration of G‐CSF required to stimulate colony formation in vitro. Autoradiographic analysis confirmed the specificity of binding since granulocytic cells were labeled but lymphocytes, erythroid cells and eosinophils were not. Blast cells and monocytic cells were partially labeled, the latter at low levels. In the neutrophilic granulocyte series, grain counts increased with cell maturity, polymorphs being the most heavily labeled but all cells showed considerable heterogeneity in the degree of labeling. Combination of Scatchard analysis of binding with autoradiographic data indicated that mature granulocytes from murine bone marrow exhibited 50–500 G‐CSF receptors per cell.
Mononuclear macrophage (M‐CFC) colony formation in semisolid media in the absence of exogenous GM‐CSF
Authors: Zinzar Svetlana N. , Den Tiberius , Holland James F. 
Published: February 2005

AbstractHuman fetal bone marrow (FBM) cells were examined for the ability to form colonies in the absence of exogenous colony‐stimulating factor (CSF) in double layer agar, methylcellulose (MC), and in agar‐MC (agar underlayer, MC overlayer) culture systems. Without exogenous CSF, macrophage colonies (M‐CFC) were formed in a combined culture of agar and MC. Aggregates of 5–40 cells were observed on day 7. Gradually, large compact colonies which survived for 10–12 weeks of cultivation, were formed. They were composed of mononuclear monocytes and multinucleated cells. M‐CFC progenitors were nonadherent, but their progeny became adherent during differentiation within the colony. Colony formation was cell‐dose‐dependent. Depletion of monocytes increased the number of colonies in agar‐MC cultures and stimulated the development of some macrophage colonies in MC. Survival of monocyte progenitors was not dependent on CSF. Neither was their proliferation nor partial differentiation in agar‐MC cultures. CSF increased M‐CFC colony efficiency, however, if it was present when cultures were initiated. Addition of CSF to M‐CFC growing for 2–5 weeks in CSF‐deprived medium stimulated monocytes proliferation and transformation into macrophages. Epithelioid cells, and increase in the number of giant multinucleated cells, and granulocyte multiplication were also observed. The absolute dependence of macrophage colony formation on CSF described by others might be a result of inadequate culture conditions due to agar rather than an intrinsic physiological requirement.
Wheat germ agglutinin and concanavalin A inhibit the response of human fibroblasts to peptide growth factors by a post‐receptor mechanism
Authors: Kaplowitz Paul B. 
Published: February 2005

AbstractThe effect of plant lectins on amino acid uptake and DNA synthesis in cultured human skin fibroblasts stimulated by various peptide mitogens was studied. Wheat germ agglutinin (WGA), at a concentration of 5 μg/ml, which by itself had little effect on 3H‐aminoisobutyric acid (AIB) uptake, markedly inhibited stimulation of 3H‐AIB uptake by somatomedin‐C, insulin, epidermal growth factor (EGF) and platelet‐derived growth factor. This inhibition could not be overcome by increasing the concentration of peptide added. Neither WGA nor concanavalin A (Con A) significantly affected basal 3H‐thymidine incorporation. However both lectins, at concentrations of 5–20 μg/ml, decreased EGF‐and insulin‐stimulated DNA synthesis while succinyl Con A, a divalent lectin derivative, did not. The inhibitory effects of lectins on mitogenic stimulation were reversed by α‐methyl mannose (Con A) or N‐acetylglucosamine (WGA), and were not due to a reduction in the binding of growth factors to their receptors. It is concluded that certain lectins noncompetitively inhibit the response of human fibroblasts to multiple peptide mitogens at the post‐receptor level, possibly by interfering with lateral mobility and aggregation of mitogen‐receptor complexes.
DNA damage production in CHO cells at elevated temperatures
Authors: Warters Raymond L. , Brizgys Lucy M. , Axtell‐Bartlett Joann 
Published: February 2005

AbstractInduction of DNA lesions in the nucleus of Chinese hamster ovary (CHO) cells was observed at hyperthermic temperatures using the alkaline filter elution and the alkaline sucrose gradient sedimentation methods. These lesions were observed principally at temperatures greater than 45°C with an activation energy of 140 kcal/mole. On alkaline sucrose gradients the cell genome was reduced to a 140 S or 2 × 108 dalton subunit of DNA independent of increasing exposure time at temperatures above 45°C. The large thermal activation energy and the limited DNA size reduction suggest the possible involvement of thermal denaturation of a nuclear polypeptide in the production of these nuclear lesions.
BrdU‐Hoechst flow cytometry reveals regulation of human lymphocyte growth by donor‐age–related growth fraction and transition rate
Authors: Kubbies M. , Schindler D. , Hoehn H. , Rabinovitch P. S. 
Published: February 2005

AbstractAn improved BrdU‐Hoechst flow assay was applied to cell kinetic studies of human lymphocyte cultures during a 24–96 hr interval after PHA stimulation. The assay shows that the duration of the initial lag phase and the proportions of noncycling cells increase as a function of donor age, whereas the rates of transition from each cell cycle compartment to the next decrease. Cell cycle arrest occurs in the first S and G2 phase after stimulation of lymphocytes from a 75‐year‐old donor but not from younger donors. The data are consistent with several models of cell cycle kinetics, so long as these models are modified to include a fraction of noncycling cells in each cell cycle compartment.
Stretch‐induced growth in chicken wing muscles: Role of soluble growth‐promoting factors
Authors: Summers Philip J. , Ashmore C. Robert , Lee Yu Bang , Ellis Stanley 
Published: February 2005

AbstractThe involvement of soluble growth‐promoting factors in stretch‐induced hypertrophy of the Patagilis muscle (PAT) in the chicken wing was investigated. Soluble extracts were prepared from young chicken PAT muscle made hypertrophic by passive stretch and from unstretched contralateral controls. Extracts were tested for their ability to stimulate cell proliferation and creatine phosphokinase (CPK) activity in primary monolayer cultures of chick embryo muscle cells.Factors were present in muscle extracts which showed a dose‐dependent stimulation of cell proliferation and CPK activity in vitro. Passive stretch for 5 days produced a rapid hypertrophy of the PAT which was accompanied by a dramatic increase in the activity of the growth factor(s). Release of stretch resulted in an arrest of growth and an immediate fall in growth factor activity.The difference in growth‐stimulating activity between control and stretched PAT extracts could be demonstrated in chicken transferrin‐sensitive chick myoblast cultures. Stretch thus induces an increase in a class‐specific growth factor, possibly Transferrin, in the PAT.Stretched PAT extracts stimulated: (a) chick myoblast proliferation to a greater extent than an optimum concentration of chick embryo extract, and (b) CPK activity in vitro to a greater extent than excess Transferrin. Both control and stretched PAT extracts supported the growth of rat myoblasts. We conclude that PAT muscle extracts also contain unknown growth factor(s) which are different from Transferrin.