bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of pH, potassium, sodium, bicarbonate, and chloride ions and glucose on the buoyant density distribution of human erythrocytes in bovine serum albumin gradients
Authors: Kneece W. C. , Leif R. C. 
Published: February 2005

AbstractThe effect of pH on the buoyant density of human erythrocytes at 4°C in bovine serum albumin (BSA) gradients has been reinvestigated. The results obtained disagree with those found by Legge and Shortman. This disagreement is due to a difference in the way “isotonic” is defined. The results in this pH study were obtained by keeping the total concentration of cations constant rather than the total concentration of solutes. This study demonstrated that when the pH of the BSA gradient is maintained between 5.7 and 7.2, by varying only the concentrations of bicarbonate and chloride ions, the value of ρtmed, the buoyant density at the truncated median of the density distribution, for human erythrocytes changes in a complex manner, but does not increase anywhere as much as previously found. The bicarbonate ion apparently is partially excluded from the human erythrocyte.Upon extrapolation to the physiological concentration of the bicarbonate ion (27.50 meq/liter), the buoyant density was found to decrease with the increasing pH.Variations in the (K+/Na+) ratio of the BSA gradient media, at a constant pH and total cation concentration, do not appear to affect significantly the buoyant density of the human erythrocyte. Increasing the concentration of glucose from 5.55 to 11.10 meq/liter also did not significantly affect the buoyant density of these cells.
Phosphate transport in ehrlich ascites tumor cells and the effect of arsenate
Authors: Levinson Charles 
Published: February 2005

AbstractThe effect of extracellular Pi and arsenate on Pi‐transport in Ehrlich ascites tumor cells has been studied. Pi‐transport can be described by Michaelis‐Menten kinetics; the maximal flux equal to 44 mmoles (kg cell water)−1 hour−1 and Km equal to 3.3 × 10−4 M. Arsenate is a competitive inhibitor of Pi‐transport with an inhibition constant (Ki) equal to 2.41 × 10−3 M.The data support the hypothesis that cellular Pi is regulated by the cell membrane through the mediation of a carrier system.
Phagocytosis and the sialic acid of the surface of polymorphonuclear leukocytes
Authors: Noseworthy John , Korchak Helen , Karnovsky Manfred L. 
Published: February 2005

AbstractTreatment of polymorphonuclear leukocytes with sialidase release about one‐half of the total sialic acid of the cells. Such treatment affects neither phagocytic ingestion nor glycolysis. These results are in contrast to earlier data in the literature that indicate suppression of both functions mentioned upon desialation of these cells. The presence of an inhibitor of glycolysis that contaminated the crude enzyme previously used is suggested.
Stimulation of uptake of tritiated thymidine into mouse marrow cells in culture by a factor from L‐cell conditioned medium
Authors: Austin P. E. , McCulloch E. A. , Till J. E. 
Published: February 2005

AbstractUptake of 3H‐thymidine into suspension cultures of mouse marrow cells was stimulated by the addition of serum‐free conditioned medium harvested from cultures of mouse L‐cells. Characterization of the “conditioning factor activity” (CFA) by gel filtration, ion exchange chromatography, velocity sedimentation, polyacrylamide gel electrophoresis and susceptibility to trypsin digestion indicated that the CFA detected by stimulation of 3H‐thymidine uptake is the same as the CFA detected previously by its ability to stimulate colony formation by marrow cells in vitro. The 3H‐thymidine uptake assay was used to investigate the kinetics of disappearance of CFA as a function of time in the presence of mouse marrow cells. The CFA recoverable from the cultures decreased rapidly during the first day, and approached background levels by the fifth day. There was no evidence of inhibitory substances in the depleted media. Even if the cultures continued to receive fresh conditioned medium at daily intervals, 3H‐thymidine uptake decreased sharply after the fifth day, indicating that the marrow cells had lost their capacity to respond to CFA.
Expression of differentiated functions in hepatoma cell hybrids. II. Aldolase
Authors: Bertolotti Roger , Weiss Mary C. 
Published: February 2005

AbstractA study of aldolases in rat hepatoma clones and subclones has revealed that they synthesize all three forms of aldolase monomers: A (the ubiquitous glycolytic isozyme), B (the form characteristic of the liver) and C, and that in vitro–in vivo passage results in a reversible modulation in aldolase A activity.Three kinds of somatic hybrids, between rat hepatoma cells and either mouse fibroblasts or rat epithelial cells, have been studied. In each case, aldolase B, found only in the hepatoma parent, was absent in the hybrid cells. The absence of aldolase B in the somatic hybrids seems not to be due to trivial factors (species differences, inactivation of all hepatoma aldolase genes, increase in ploidy or loss of chromosomes); it is concluded that extinction of this differentiated function of the hepatoma parent reflects a genetic regulatory phenomenon.
Arrest of chinese hamster cells in G2 following treatment with the anti‐tumor drug bleomycin
Authors: Tobey Robert A. 
Published: February 2005

AbstractUpon addition of bleomycin (BLM) to suspension cultures of Chinese hamster cells (line CHO), cells closer to prophase than 56 minutes continue dividing at the normal rate, whereas cells at earlier positions in the cell cycle either fail to reach mitosis altogether (at 200 μg/ml) or enter mitosis and divide at a reduced rate at lower drug concentrations. At 100 μg/ml of BLM (the rate of cell division slowed to a doubling time of 167 hours), initiation and termination of DNA synthesis occur at normal rates, resulting in an accumulation of cells with a G2 DNA content in the first 130 minutes of G2. Bleomycin effects are not readily reversible. The rates of incorporation of leucine, uridine, or thymidine into cells treated for six hours with 100 μg/ml of BLM were 90, 85, and 80%, respectively, of the values obtained in control cultures, suggesting that the effects of BLM on cell‐cycle traverse cannot be correlated with gross inhibition of macromolecular synthesis.
The influence of calcium on the cyclic AMP‐mediated stimulation of DNA synthesis and cell proliferation by prostaglandin E1
Authors: Whitfield J. F. , Macmanus J. P. , Braceland B. M. , Gillan D. J. 
Published: February 2005

AbstractProstaglandin type E1 (PGE1) rapidly stimulates cyclic AMP formation and the initiation of deoxyribonucleic acid (DNA) synthesis in rat thymic lymphocytes suspended in vitro by reactions which are not affected by wide variations in the extracellular calcium concentration. On the other hand, the operation of the associated reaction(s) responsible for the subsequent progression of the stimulated cells into mitosis is profoundly affected by the extracellular calcium level. If the maximum intracellular cyclic AMP concentration is in the lower range of stimulatory values (e.g., 150 × 10−8 picomoles per cell as produced by an exposure to 0.5 μg of PGE1 per milliliter of medium), an extracellular calcium concentration of 0.5 to 1.0 mM is needed to obtain maximum cell proliferation, but not the maximum stimulation of DNA synthesis. Contrariwise, if the cellular cyclic AMP content is raised to a much higher level (260 × 10−8 picomoles per cell) by exposure to a greater PGE1 concentration (5.0 μg per millilter), cell proliferation is maximally stimulated in calcium‐free medium and increasing the extracellular calcium concntration above 0.2 mM actually prevents the stimulation of cell proliferation (but does not affect the stimulation of DNA synthesis). Thus, the ultimate translation of PGE1's early cyclic AMP‐mediated reactions into increased cell proliferation is determined by both the intracellular cyclic AMP level and the extracellular calcium concentration.
Hemopoietic colony studies. VI. Increased eosinophil‐containing colonies obtained by antigen pre‐treatment of irradiated mice reconstituted with bone marrow cells
Authors: Jenkins V. K. , Trentin J. J. , Speirs R. S. , McGarry M. P. 
Published: February 2005

AbstractThe cellular response to an intraperitoneal injection of antigen (tetanus toxoid) was studied in reconstituted animals in order to determine the mechanism of control of eosinophil granulocytopoiesis. Antigen treatment of the marrow cell donors did not consistently increase the number of spleen and bone marrow colonies in recipient animals or change the percentage of eosinophil or other hemopoietic colony types. Antigen pre‐treatment of the irradiated recipients increased the percentage of eosinophil‐containing colonies in the spleen and femoral bone marrow without significantly changing the total number of either spleen or marrow colonies. Antigen treatment of both the bone marrow cell donor and recipient produced a further increase in the percentage of eosinophil‐containing colonies in the marrow cavity, but not in the spleen. Antigen treatment of the irradiated recipient increased the number of eosinophilic cells (but not the total number of cells) in both the peritoneal cavity and the bone marrow. Antigen treatment of both the marrow donor and recipient produced a further increase in the number of eosinophilic cells in the peritoneal cavity, but not in a single femur. Since antigen treatment of the marrow recipient, or recipient and donor, but not of the marrow donor alone, results in increased eosinophilic cell and colony numbers, the effect of antigen appears to be mediated through some host factor(s), perhaps the eosinophilic hemopoietic inducing microenvironment (HIM), rather than directly on the hemopoietic stem cells.
Cloning of mouse myeloma cells and detection of rare variants
Authors: Coffino Philip , Baumal Reuben , Laskov Reuven , Scharff Matthew D. 
Published: February 2005

AbstractCultured mouse myeloma cells have been cloned in soft agar using a modification of the method established by Pluznik and Sachs ('65, '66) and by Bradley and Metcalf ('66). A linear relationship existed between the number of cells plated and the number of colonies produced. Conditions for obtaining optimum cloning efficiency and colony size were determined for the MPC‐11 cell line. Feeder cells of mouse, human and rabbit origin and conditioned growth medium obtained from mouse cultures and had an enhancing effect on colony formation. Immunoglobulin production by cloned cells was detected by overlaying the clones with anti‐immunoglobulin antiserum. The antiserum had no adverse effect on cloning efficiency or colony size. A reconstruction experiment was performed to show that the plate assay could reliably detect rare variants of immunoglobulin producing cells. The plate assay was validated by studying immunoglobulin production following recovery of clones from dishes and their growth to mass suspension culture. Immunoglobulin formation in these cultures was assessed by a Ouchterlony immunodiffusion of the supernatant medium, and by incubating the cells with radioactive amino acids and analyzing the intracellular and secreted immunoglobulin on polyacrylamide gels.
Multiple sensitivity of single taste cells of the frog tongue to four basic taste stimuli
Authors: Sato Toshihide 
Published: February 2005

AbstractThe electrical response of the taste cells of the frog fungiform papillae to four fundamental taste solutions (NaCl, acetic acid, quinine‐HCl and sucrose) was studied by using the intracellular recording technique. The average value of resting membrane potential was 22.5 mV, inside negative. Each of the four taste solutions applied to the tongue produced a slow depolarizing potential, the receptor potential, on which no spike potential was superimposed. The amplitude of the receptor potentials increased linearly as a function of the logarithm of the concentration of the stimulus. Amplitudes of depolarizations to a given taste stimulation varied from one cell to another even within a single taste bud. Most of the cells responded to more than two of the four basic taste solutions. Sensitivity patterns in terms of the number of effective solutions and the relative effectiveness of different kinds of solutions were variable among cells. Statistical analysis suggests that at the receptor membranes of the taste cells, the sensitivities for the four basic stimuli are independent and random.
Ammonia effects in cultures of normal and transformed 3T3 cells
Authors: Visek W. J. , Kolodny G. M. , Gross P. R. 
Published: February 2005

Abstract3T3 and SV‐40 transformed 3T3 mouse fibroblasts were cultured in media with serum and antibiotics plus ammonia (NH3 z NH4+) added as NH4C1. Both cell lines cultured without added ammonia showed normal morphology and multiplication even though ammonia in the medium at the end of the culture period ranged from 35 to 48 μg/ml. Ammonia concentrations being significantly higher in media removed from cells at the end of the culture period than in media incubated identically without cells, verified that cells released substantial quantities of ammonia in addition to components of the medium which underwent spontaneous breakdown. Both cell lines showed changes in morphology and highly significant reductions in cell multiplication which increased progressively as the concentration of added ammonia on the initial day of culture was increased to 35μg/ml. Control 3T3 cultures released significantly greater quantities of ammonia per cell than control cultures of transformed cells but their multiplication was more adversely affected by added ammonia. There were downward shifts in pH of the culturing medium for both cell lines as culture age increased at all concentrations of added ammonia, However, significant reductions in cell multiplication resulted from additions of ammonia that did not produce significant changes in extracellular pH. The data show that studies upon the effects of pH of the medium on cultured cells require control of ammonia concentrations.
Contact inhibition of what? An analytical review
Authors: Martz Eric , Steinberg Malcolm S. 
Published: February 2005

AbstractQuite a number of phenomena having to do with cells' influences upon one another's movements have come to be regarded as expressions of “contact inhibition.” However, no single, central mechanism has been shown to underlie them all. Consequently, the term “contact inhibition” should not be used without operational modifiers. Inhibitions of individual cell movements imputed to be mediated by cell‐cell contacts include inhibition of overlapping (which results in monolayering), of colony expansion, of cell speed (nuclear translocation), of ruffling, of orthogonal movement (proposed to explain spontaneous parallel alignment of cells), and of neighbor exchanges.The six inhibitions listed above are operationally distinct, and only two (overlapping and colony expansion) are known to result from a common mechanism. A seventh phenomenon, so‐called “contact inhibition of cell division” (more operationally termed postconfluence inhibition of cell division) is in a separate category and is not considered here.Evidence eliminating action‐at‐a‐distance is available only for the first three, and hence only these should at present be termed contact inhibitions. Inhibition of neighbor exchanges is yet hypothetical; at its extreme, it would immobilize cells in a confluent monolayer, but such immobilization has been found not to occur.Contact inhibition of overlapping, the most studied of the six, is not displayed by invasive cells with respect to normal cells; invasive tumor cells overlap freely upon normal cells, although not necessarily upon one another. Contact inhibition of overlapping, and its loss by invasive cells, can readily be interpreted, by means of the differential adhesion hypothesis, as consequences of cell‐type‐specific differences in cell‐cell and cell‐substratum “strengths of adhesion.” These strengths of adhesion are formulated as specific interfacial free energies, which are the only parameters of cellular adhesiveness that have been rigorously shown to determine equilibrium configurations of cell populations.
Loss of density‐dependent regulation of multiplication of BALB/3T3 cells chemically transformed in vitro
Authors: Oshiro Y. , DiPaolo J. A. 
Published: February 2005

AbstractBalb/3T3 cells show density‐dependent regulation of multiplication with the final cell density depending on serum concentration in the media. Chemically transformed Balb/3T3 cells (Balb/3T3‐D) pile up on each other, multiply to a high cell density, but have decreased DNA synthesis at very high cell densities. Balb/3T3‐D cells require less serum for multiplication compared with original Balb/3T3 cells. A rat serum fraction and a bovine β‐globulin fraction stimulate the multiplication of Balb/3T3 cells but only slightly stimulate Balb/3T3‐D cells indicating different serum factors stimulate growth of these two cell types. The multiplication properties of Balb/3T3‐D cells are very similar to those of SV‐40 transformed 3T3 cells, however, these properties were brought about by a single treatment by a chemical carcinogen, without an exogenous virus. The transformation altered the contact of cells to one another, indicating a permanent chemical change in the membrane structure.
Clone size variation in the human diploid cell strain, wi‐38
Authors: Merz George S. , Ross John D. 
Published: February 2005

AbstractBy mapping the location of isolated single cells; and then counting the number of cells at each location as a function of time. it was possible to accumulate data on the growth history for each of a large group of clones. The clone size distribution, its mean and standard deviation were computed for each day in culture. Variations in schedule of medium change and time of exposure to trypsin, did not measurably affect variation in clone size. Neither could clone size variation be accounted for on the basis of (1) occurrence of nondividing cells nor (2) presence of heritable growth rate variants in the population. It is probable that clone size variation under our conditions is primarily a consequence of a highly variable interdivision time among the constituent cells.
Action spectrum for a low intensity, rapid photoinhibition of mechanically stimulable bioluminescence in the marine dinoflagellates Gonyaulax catenella, G. acatenella, and G. tamarensis
Authors: Esaias Wayne E. , Curl Herbert C. , Seliger Howard H. 
Published: February 2005

AbstractThe mechanically stimulable bioluminescence of members of the Gonyaulax catenella group can be maximally photoinhibited by exposure to as few as 1013 quanta/cm2, a factor 104 times smaller than that required for comparable photoinhibition in Gonyaulax polyedra and all other photosynthetic bioluminescent dinoflagellates investigated. Following an irradiation pulse there is an initial time lag of one minute, followed by a rapid decrease in mechanical stimulability to approximately 1% of the dark unirradiated control with a firstorder rate constant as high as 0.01 sec−1. Action spectra for all three species imply a pigment with a single absorption band having a maximum at 562 nm and a half band width of 105 nm within the spectral range 325 nm to 775 nm. Photoinhibition appears to decrease either the sensitivity of the shear receptor mechanism or the efficiency of signal transmission in the dinoflagellates, since chemically stimulable bioluminescence is unaffected by these exposures.
Calcium transport in isolated bone cells I. Bone cell isolation procedures
Authors: Dziak Rosemary , Brand John S. 
Published: February 2005

AbstractBone cells were isolated by collagenase‐hyaluronidase digestion of 19–20 day‐old fetal rat calvaria. It is shown that contamination from calcified matrix can give erroneously high values for total cell calcium and can mask intracellular calcium exchange.Filtration of the cell suspension through 35 μ mesh nylon net and a five minute treatment with a cold pH 6.0 isotonic salt solution removed the contamination. Total calcium for cells prepared in this manner was 16.8 mmoles/kg wet weight. 45Ca uptake studies revealed an active component of calcium exchange.
The membrane potentials of fibroblasts in different environments
Authors: Bard J. , Wright M. O. 
Published: February 2005

AbstractThe membrane potentials of human embryonic lung fibroblasts have been measured in different cellular environments. Sparse cells on plastic have a mean membrane potential of −8.5 mV. As the cells progress to dense culture, the mean membrane potential rises to −14.7 mV. The mean membrane potential of fibroblasts in human embryonic lung fragments by comparison was found to be −16.5 mV. Sparse cells on collagen, at the same density as the sparse cells on plastic, have mean membrane potentials of −10.8 mV.Sparse cells on plastic migrating from dense cellular areas, following a cut being made in a thick sheet of cells, have mean membrane potentials of −5.9 mV.The significance of these results in relation to cellular environments has been discussed.
Electrical sizing of particles in suspensions IV. Lymphocytes
Authors: Ben‐Sasson S. , Patinkin D. , Grover N. B. , Doljanski F. 
Published: February 2005

AbstractThe factors involved during the pumping of a particle suspended in an electrolyte through a small cylindrical orifice across which exists an electric field are reviewed, and their practical application to cell volume measurement in terms of orifice geometry and particle properties is considered. Procedures are described to determine whether a particular cell type satisfies the operational criteria of a rigid, non‐conducting sphere, for which the theoretical expressions can be reduced to an especially simple form under appropriate conditions.Experimental results are presented for the case of chick, mouse and human lymphocytes, all of which are shown to satisfy the above requirements. Volume distributions are provided for chick blood lymphocytes and compared with those from various lymphatic organs; representative data are also reported for different types of mouse lymphocytes. Human blood lymphocytes are found to have normally‐distributed diameters (p > 98%), a property not shared by their volumes or their surface areas, nor by blood lymphocytes from the chick or from patients with chronic lymphatic leukemia. A possible implication of this finding is mentioned briefly.
Change of chromatin morphology during the cell cycle detected by means of automated image analysis
Authors: Sawicki Wojciech , Rowinski Jan , Swenson Ronald 
Published: February 2005

AbstractMouse embryo fibroblasts growing asynchronously in vitro stained with Feulgen method and their nuclear chromatin was analysed by means of the image analysing computer Quantimet 720D. Cells with 2C, 3C and 4C content of DNA were considered as being in G1, middle S and G2 phase of cell cycle, respectively. It was found that the projected area of nuclei increases during the cell cycle and that the mean optical density of chromatin increases from G1 through S to G2 phase. The curves showing the areas of chromatin at different optical density thresholds are different for cells in G1, S and G2 phase. The results demonstrate cyclic changes in chromatin morphology in the interphase nuclei during the cell cycle.