bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modulation of epithelial cell proliferation in culture by dissolved oxygen
Authors: Taylor William C. , Camalier Richard F. 
Published: February 2005

AbstractModulation of epithelial cell proliferation by the dissolved oxygen concentration (PO2) of the growth medium was assessed with primary human foreskin epithelium and a continuous monkey kidney epithelial cell line (LLC‐MK2). Direct measurement of the growth medium PO2 provides the first quantitative evaluation of epithelial cell proliferation as a function of PO2 provides the first quantitative evaluation of epithelial cell proliferation as a function of PO2. Sustained proliferation of LLC‐MK2 cells occurs in serum‐free medium equilibrated with a gas phase containing 18% or 30% O2 v/v. Mid‐logarithmic phase cultures rapidly consume dissolved oxygen; this results in a 60–70 mm Hg decline in PO2 and leads to a stable growth medium PO2 between 70 and 100 mm Hg, well above anoxic values. In contrast, if culture medium is equilibrated with a gas phase containing 0% or 1% O2 v/v to yield a growth medium PO2 ∼ 20–40 mm Hg, proliferation of LLC‐MK2 and primary foreskin epithelial cells is retarded, and LLC‐MK2 cells use little dissolved oxygen. Gentle, continuous rocking to prevent diffusion gradient formation enhances proliferation slightly at the higher PO2, but neither periodic fluid renewals nor continued rocking stimulates cells retarded by a lowered oxygen concentration to resume proliferation. The data collectively demonstrate that epithelial cell proliferation requires a PO2 > 40 mm Hg, and threshold requirements are probably closer to 70 mm Hg. Glycolysis continues at a PO2 insufficient for proliferation, but more lactic acid accumulates in actively proliferating cultures than in cultures equilibrated with 0% oxygen. We conclude that epithelial cells in vitro both consume more oxygen and require a higher PO2 for continued proliferation, and that the oxygen requirement for epithelial cell proliferation exceeds that of a comparable population of fibroblasts for which low oxygen may enhance survival and proliferation.
Rous sarcoma virus transformed cells are resistant to cyclic AMP
Authors: Roth Charles W. , Singh Toolsee , Pastan Ira , Gottesman Michael M. 
Published: February 2005

AbstractA nontransformed line of Chinese hamster ovary (CHO) cells (Pollard and Stanners, 1979) has been transformed by the Schmidt‐Ruppin subgroup D strain of Rous sarcoma virus (SR‐RSV). SR‐RSV transformed CHO cells are shown to differ from spontaneously transformed cells in that the virally transformed cells are more resistant to growth inhibition or changes in cell shape by 8‐Br‐cyclic AMP or cholera toxin. SR‐RSV transformed rat (NRK) cells also have a reduced sensitivity to growth inhibition by 8‐Br‐cyclic AMP. Cyclic AMP‐dependent protein kinase was examined in SR‐RSV transformed CHO cells, but no differences in enzyme level, activation by cyclic AMP, chromatographic behavior, or its ability to phosphorylate endogenous proteins in whole cells could be detected. It is concluded that transformation of CHO and NRK cells by SR‐RSV alters the cells in a manner different from spontaneous transformation, and that this alteration does not affect cAMP‐dependent protein kinase activity.
Separation of isolated hamster intestinal epithelial cells by velocity sedimentation on Ficoll gradients
Authors: Carter Julia H. , Poretz R. D. , Eichholz Alexander 
Published: February 2005

AbstractIsolated hamster intestinal epithelial cells can be separated by velocity sedimentationion on 2–10% Ficoll gradients into three subpopulations of cells which differ in morphology, biochemistry, physiology, and membrane components. These subpopulations are not pure but are enriched in a single cell type to the extent that differences in cell function can be observed. The proliferative crypt cells are separated from the digestive‐absorptive villus cells. A third subpopulation with a distinctive morphology is also obtained. Quantitation of DNA recoveries from the gradients indicates that this population constitutes approximately one‐third of the epithelial cell population. These carrot‐shaped cells are found adjacent to the digestive‐absorptive columnar epithelial cells on the villus. The two types of villus cells differ in glycolipid or glycoprotein components of the brush border as shown by lectin binding experiments with the isolated cells. The gradient data also suggest that only one‐third of the intestinal epithelial cell population is responsible for most monosaccharide absorption in hamster small intestine.
Transport of 6‐deoxy‐D‐glucose and D‐xylose by untransformed and SV40‐transformed 3T3 cells
Authors: Romano Antonio H. , Connell Nancy D. 
Published: February 2005

AbstractTransport rates of the nonphosphorylated D‐glucose analogs 6‐deoxy‐D‐glucose and D‐xylose were measured in quiescent and serum‐stimulated cultures of mouse 3T3 cells, in SV40‐transformed 3T3 cells (SV101), and in a density revertant cell line derived from SV101 (Fl‐SV101). Initial rates of both entry and exit of 6‐deoxy‐D‐glucose and D‐xylose were more than threefold higher in serum‐stimulated 3T3 and in SV101 cells than they were in quiescent 3T3 cells, but transport rates were not higher in the transformed cells (SV101) than they were in serum‐stimulated 3T3. Confluent cultures of Fl‐SV101 showed lower rates of transport than serum‐stimulated Fl‐SV101, but not as low as quiescent 3T3 cells. These data confirm previous findings of others with other analogs that glucose transport is one of the cell functions that is depressed when 3T3 cells enter the quiescent G0 state, but emphasize that SV40‐transformed 3T3 cells do not show higher activity of the D‐glucose carrier than do actively growing 3T3 cells. Thus, enhanced glucose transport appears not to be a specific consequence of transformation, but a reflection of the active growth state of the cell.
Altered cell cycle progression and aberrant mitosis in adenovirus‐infected rodent cells
Authors: Murray James D. , Bellett Alan J. D. , Braithwaite Antony W. , Waldron Lydia K. , Taylor Ian W. 
Published: February 2005

AbstractActively growing mouse or rat embryo cells suffered structural chromosome damage, mitotic anomalies, and polyploidy after infection by human adenovirus type 5. Chromosome damage required expression of one or more early viral genes and showed regular periodicity in its frequency. The growth cycle time of some of the infected cells was reduced by about 5 hours due to a decrease in G1, and the interval between successive waves of chromosome damage corresponded to this reduced cycle time. After infection there was a decrease in cells with G1 DNA content and an increase in cells with G2 diploid, aneuploid, and polyploid DNA contents. We suggest these effects are due to the expression in semipermissive cells of early viral gene(s), whose function in productive infection in vivo is to alter cell cycle controls in order to maximize the number of cells able to replicate viral DNA and the time such cells spend in DNA replication.
Characterization of a postlavage, in situ pulmonary macrophage population
Authors: Drath David B. , Davies Paul , Shorey Jeannette M. , Gibran Nicole S. , Simpson Paul J. , Huber Gary L. 
Published: February 2005

AbstractA postlavage in situ subpopulation of pulmonary macrophages (PM), biochemically distinct from the lavaged population, has recently been isolated from rats. After exhaustive bronchopulmonary lavage to extract the free lung cells, the lungs were excised, homogenized, and filtered, and the resultant cell suspension was allowed to form a monolayer on plastic Petri dishes. Electron microscopic morphometry failed to indicate any morphologic differences in the two populations. The postlavage in situ PM were more active metabolically during phagocytosis of zymosan particles or stimulation by phorbol myristate acetate (PMA) than the corresponding lavage population, as evidenced by greater superoxide generation. Macrophages prepared by either method became more avidly phagocytic when incubated with cell‐free medium isolated in the preparation of the in situ population. Peroxidase, an enzyme absent from the granules of PM separated by lavage techniques, was found in a granule‐rich fraction of the in situ macrophage. Catalase activity was found in similar amounts in both supernatants and granule‐rich fractions of both populations. The results support the concept of subpopulations of PM and suggest that these subpopulations are distinguished by their biochemical properties and their functional abilities.
Ornithine decarboxylase induction and the cytoskeleton in normal and transformed cells
Authors: Rumsby Gillian , Puck Theodore T. 
Published: February 2005

AbstractODC induction by fresh medium added to stationary, medium‐depleted, confluent cultures has been studied in transformed HeLa and CHO cells, and in normal human fibroblasts as an indicator of the resumption of cell multiplication. The transformed HeLa cell displays a more easily reversed G1 block, a higher peak ODC level, and a shorter time period for achievement of the peak ODC value than does the normal fibroblast. Low concentrations of microtubule depolymerizing agents like colchicine suppress ODC induction almost completely in the normal fibroblast, but hardly at all in the HeLa or CHO cells. Both transformed cells occasionally reveal a superinduction of ODC at very low colchicine levels (10−8‐10−7 M) and a more variable response to such agents than does the normal fibroblast. Higher concentrations of colchicine suppress ODC induction in all cells. Experiments with actinomycin D and cycloheximide indicate that the principal colchicine action involves inhibition at the level of protein or mRNA synthesis, rather than inactivation of the already synthesized enzyme. These experiments are provisionally interpreted as an indication that a microtubular system is needed to reinitiate certain steps associated with growth in G1‐blocked, normal cells, and that a second microtubular action terminating enzyme biosynthesis may exist. This microtubular control is defective in the transformed cells here studied. Specific microtubular actions necessary for initiation and termination of protein syntheses may occur throughout the cell reproductive cycle, and in the course of normal differentiation processes.
Effects of 12‐0‐tetradecanoylphorbol‐13‐acetate (TPA) on rat pheochromocytoma (PC12) cells: Interactions with epidermal growth factor and nerve growth factor
Authors: End David , Tolson Nathaniel , Yu Mei‐Ying , Guroff Gordon 
Published: February 2005

AbstractThe phorbol ester tumor promoter 12‐0‐tetradecanoylphorbol‐13‐acetate (TPA) specifically inhibited the binding of radioiodinated epidermal growth factor (125I‐EGF) to rat pheochromocytoma (PC12) cells in a noncompetitive fashion with an apparent Ki of 11–26 nM. Both TPA and EGF elicited similar biological responses in PC12 cells including enhanced incorporation of 3H‐choline and 32P‐orthophosphate into macromolecules, induction of ornithine decarboxylase, and stimulation of the phosphorylation of a 30,000 MW nonhistone, chromosome‐associated protein. These effects were also elicited by nerve growth factor (NGF) which, in contrast to the former agents, is a differentiating stimulus for the PC12 cells. The effects of TPA were additive or more than additive to the effects of NGF and EGF. When PC12 cells were induced to differentiate by treatment with NGF for 72 hours, the binding of 125I‐EGF and responses to EGF were reduced by approximately 70%. The response of PC12 cells to the tumor promoter TPA was unaffected by treatment with NGF. Thus, the qualitatively similar effects of TPA and EGF seemed to be mediated through separate receptor systems with only the EGF receptor system reduced by NGF treatment.
Interactions of lectins with CHO cell surface membranes. I. Competition studies indicate concanavalin A and WGA bind to discrete populations of sites
Authors: Emerson D. , Juliano R. L. 
Published: February 2005

AbstractThe binding of radioiodinated lectins to the CHO cell surface was measured for the following affinity purified plant agglutinins; concanavalin A, wheat germ agglutinin, Ricinus agglutinins (I, II), pea agglutinin, peanut agglutinin, and Bandeiria simpliciafolia agglutinin (BSLI). The number of binding sites at saturation ranged from 6 × 105for BSL 1 to 5 × 107 for pea and Ricinus. Affinity constants calculated by the Steck‐Wallach procedure ranged from 2 × 105m−1L for pea lectin to 4.5 × 106 M−1 L for peanut lectin. Competition studies between homologous and heterologous radiolabeled and unlabeled lectins indicated that homologous unlabeled lectin could fully block binding of radiolabeled lectin. For heterologous pairs, a variety of results were observed. Of particular interest is the finding that concanavalin A and wheat germ agglutinin mutually failed to compete for binding indicating that these two lectins bind to distinct, nonoverlapping populations of surface sites. This finding suggests that the binding sites for WGA and Con A reside, for the most part, on discrete populations of membrane molecules; this concept is further validated in a companion paper in the upcoming issue of this journal (Schwartz et al., 1982).
Interactions of lectins with CHO cell surface membranes. II. Differential effects of local anesthetics on endocytosis of CON A and WGA binding sites
Authors: Schwarz M. A. , Harper P. A. , Juliano R. L. 
Published: February 2005

AbstractUsing fibroblastic CHO cells, we have examined (1) the internalization and redistribution of surface binding sites for the lectins Concanavalin A and wheat germ agglutinin and (2) the sensitivity of these processes to putative inhibitors of cytoskeletal activity. Following initial exposure to fluorescein conjugated Con A (CAF) or WGA (WGAF) at 4° C, kinetic analysis of internalization and intracellular aggregation of lectin at 37°C indicated more rapid aggregate formation in the case of WGA than in the case of Con A. Treatment with tertiary amine local anesthetics (tetracaine, dibucaine, and xylocaine) or with a lysosomatrophic amine, m‐dansyl cadaverine, blocked internalization of Con A but not of WGA. Similar differential effects on redistribution of Con A and WGA were not however observed with the antimicrotubule agents colchicine and nocodazole. Simultaneous treatment of cells with WGAF and with rhodamine labeled Con A (CAR) resulted in the accumulation of both labels in a central perinuclear aggregate; a similar experiment in the presence of local anesthetic resulted in a diffuse peripheral distribution of CAR and a central aggregate of WGAF. These results suggest (1) CHO cells possess at least two distinct pathways for lectin internalization and redistribution, which can be discriminated in terms of drug sensitivity; (2) CHO cells can sort out and independently internalize different populations and lectin binding sites; and (3) different pathways may be a manifestation of biochemically distinct linkages between cytoskeletal elements and various groups of surface glycoproteins. Present findings concur with our previous results concerning the mutual independence of the surface binding sites for Con A and WGA (Emerson and Juliano, 1982).
Relation between sodium‐coupled amino acid and sugar transport and sodium/potassium pump activity in isolated intestinal epithelial cells
Authors: Sepúlveda F. V , Burton K. A. , Brown P. D. 
Published: February 2005

AbstractCells isolated from the epithelium of the small intestine are used to study the relationship between amino acid or sugar‐coupled sodium transport and potassium uptake through the sodium/potassium pump. Potassium influx is a saturable function of the external potassium concentration. Uptake in the presence of ouabain, a specific pump inhibitor, is greatly reduced. This remaining influx is linearly related to the concentration up to 6 mM potassium. Sugars and amino acids are actively accumulated by the intestinal cells. Their transport is accompanied by an initial extra influx of sodium. Although cells seem to regulate their internal sodium concentrations, this is not accompanied with a concomitant increase in potassium uptake through the pump. Thus L‐alanine, 3‐0‐methyl‐D‐glucoside, and α‐methyl‐D‐glucoside all fall to increase the rate of ouabain‐sensitive potassium uptake. A very high coupling ratio of sodium efflux to potassium influx through the pump would be a likely explanation of the present results though they cannot be regarded as conclusive.
Enzymatic modification of the surface carbohydrates of friend erythroleukemic cells
Authors: Suyama Kimita , Goldstein Jack 
Published: February 2005

AbstractSurface carbohydrates of Friend erythroleukemic‐cells were modified by treatment with the exoglycosidases, α‐galactosidase, β‐galactosidase, and neuraminidase without affecting cell growth and viability either in the presence or absence of 1.8% DMSO as inducer. When cells were incubated with a combination of α‐galactosidase and neuraminidase and then induced, they showed an increased rate of differentiation as measured by the formation of benzidine‐positive cells. These enzymes used singly, or β‐galactosidase treatment alone, or in combination with neuraminidase, did not change the rate of differentiation. Cell‐surface labeling and electrophoretic separation of the glycoconjugates revealed that two regions of approximate molecular weights of 195,000 and 185,000 were neuraminidase‐sensitive and one other of molecular weight of about 75,000 was sensitive to α‐ galactosidase. Both untreated and the combined α‐galactosidase, neuraminidase‐modified cells exhibited the same rate of uptake of carbon‐14 DMSO, ruling out the possibility that the observed increased rate of differentiation was due to faster penetration of DMSO into enzyme‐treated cells. On the other hand, the decrease in the rate of uptake of rubidium ‐ 86, an analogue of K+, by treated‐induced cells was significantly enhanced over that observed with untreated‐induced cells, suggesting that α‐galactosidase plus neuraminidase modification of the cell surface was affecting at least one of the early events occuring in the Friend erythroleukemic cell differentiation program.
Rna dependence in the cell cycle of V79 cells
Authors: Fujikawa‐Yamamoto Kohzaburo 
Published: February 2005

AbstractThe cell cycle of V79 Chinese hamster lung cells synchronized by hydroxyurea was investigated by flow cytometry. The metachromatic fluorochrome acridine orange was used to differentially stain DNA and RNA of V79 cells. Green and red fluorescence from individual cells, representing cellular DNA and RNA, respectively, was measured by flow cytometry. Periodic changes of cellular DNA and RNA contents were observed over nine cell cycles. The duration of G1, S, and G2 + M phases of synchronized V79 cells whose RNA content was close to that of the cells in balanced growth was 3, 4.5, and 1.5 hours, respectively. The duration of G1 and S phases of cells containing RNA above a certain threshold was inversely proportional to the RNA content. The RNA content of cells containing RNA above the normal level regressed to normal after a few generations. Coefficients of variation for RNA content were significantly larger than those for DNA. An explanation for the decay of synchrony in a synchronized cell population is proposed.
Effects of serum fractions on the growth of mononuclear phagocytes
Authors: Yen Shing‐Erh , Stewart Carleton C. 
Published: February 2005

AbstractThe effects of serum fractions on the growth kinetics and colony formation of mononuclear phagocytes derived from mouse bone marrow, blood, and peritoneal cavity were investigated. Peritoneal exudate macrophages and blood monocytes required a factor(s) found to reside in the nondialyzable serum fraction (molecular weight > 12,000) to survive, a small molecular weight (< 307) factor(s) with growth‐stimulatory activity (GSA) contained in the dialyzable serum fraction, and the macrophage growth factor (MGF) for proliferation and colony formation. Fetuin, a major protein of fetal serum, was able to substitute the non‐dialyzable serum fraction. Macrophages cultured in medium containing MGF and the nondialyzable serum fraction for 6 days could be restored to full growth following the addition of the dialyzable serum fraction. In contrast, bone marrow mononuclear phagocytes cultured in the absence of the dialyzable serum fraction were capable of proliferating, though at a slower rate, and forming colonies. In addition, neither insulin nor hydrocortisone was capable of replacing the serum‐dialyzable GSA nor able to enhance colony formation.
Analysis of purified fetal liver hemopoietic progenitor cells in liquid culture
Authors: Nicola Nicos A. , Metcalf Donald 
Published: February 2005

AbstractThe action of different types of colony‐stimulating factors (CSFs) on purified fetal hemopoietic progenitor cells in liquid cultures was studied. Three types of CSF were examined–pregnant mouse uterus extract (PMUE), which contains macrophage CSF; mouse lung conditioned medium (MLCM), which contains granulocyte‐macrophage CSF; and pokeweed mitogen‐stimulated spleen cell‐conditioned medium (PWM‐SCM), which contains ganulocyte‐macrophage, eosinophil, megakaryocyte, and erythroid CSFs. Without a source of CSF, the cells died within 48 hr, but with CSF, cells entered an exponential growth phase within 18 hr with a doubling time of about 12 hr. Althogh growth was best with PWM‐SCM, this appeared to be due to increased numbers of surviving cells during the early period of culture and a decreased lag phase rather than a shortening of the doubling time. With PWM‐SCM, the absolute increase in cell number was 40‐fold. Over the culture period of seven days, the blast cells also differentiated morphologically to end cells, although differentiation appeared to be highly asynchronous. With MLCM and PMUE, only cells in the granulocyte‐macrophage series were seen, but with PWM‐SCM, erythroid cells were also observed. PMUE neither stimulated nor allowed the survival for longer than two days of granulocyte or erythroid committed progenitors (CFC) but, in contrast, stimulated a marked increase in macrophage CFC, which were uniquely responsive to PMUE stimulation. The proliferation of these progenitors appeared to be actively inhibited by PWM‐SCM. Despite the inability of MLCM to stimulate mature erythroid cell production, it was able to stimulate the early proliferation of erythroid CFC as well as granulocyte‐macrophage CFC. PWM‐SCM was able to stimulate the early and late proliferation of all types of CFC.
Stimulation of embryonic mouse limb bud mesenchymal cell growth by peptide growth factors
Authors: Kaplowitz Paul B. , D'ercole A. Joseph , Underwood Louis E. 
Published: February 2005

AbstractThe possible role of peptide growth factors in mammalian intrauterine cell growth has been investigated using primary cultures of undifferentiated mesenchymal cells from 11‐day mouse embryo limb buds. When grown as monolayer cultures, proliferation is greatly favored by high cell densities. In medium containing 0.2% serum, purified epidermal growth factor (EGF), fibroblast growth factor (FGF), multiplication stimulating activity (MSA), insulin, and somatomedin‐C (Sm‐C) do not increase cell growth, but a 30–40,000 molecular weight component of mouse fetal liver conditioned medium is stimulatory. On the other hand, when limb bud cells are grown as high density or micromass cultures, a method which better approximates in vivo growth conditions, all of the purified growth factors tested stimulate cell growth significantly. These growth factors have additive effects when used in combination, the best stimulation being observed with liver medium (10% v/v), EGF (10 ng/ml), FGF (200 ng/ml), and either insulin (1 m̈g/ml) or Sm‐C (20 ng/ml). We conclude that the response of limb bud cells to growth stimulation is influenced by the manner in which the cells are cultured and that at least four different growth factors are required for optimal in vitro proliferation. One of these, the active component of liver medium, appears to be a previously uncharacterized growth factor.