bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cation exchange binding of rubidium and cesium by rat liver cell microsomes
Authors: Sanui Hisashi 
Published: February 2005

AbstractThe rubidium and cesium binding characteristics of rat liver cell microsomes were studied by an equilibration, centrifugation and washing procedure. Concentration dependence experiments, in which microsomes were equilibrated in media containing 0 to 400 mM rubidium or cesium chloride at pH 6.9, yielded saturation type adsorption isotherms similar to those previously reported for sodium and potassium. Mass law analysis of the data yielded apparent dissociation constants of 21 × 10−3 eq/liter and 19 × 10−3 eq/liter for rubidium and cesium binding, respectively. The results indicate that cesium is bound slightly more strongly than rubidium, and that both these cations may be bound more strongly than sodium or potassium. The maximum binding capacity at pH 6.9 was approximately 1.3 meq rubidium or cesium/g nitrogen. Sodium, potassium, magnesium and calcium generally associated with the isolated microsomes decreased concomitantly with increasing bound rubidium or cesium, demonstrating the ion exchange nature of the binding. Results of pH‐dependence experiments showed that following equilibration of the microsomes in media containing approximately 96 mM rubidium or cesium at various pH values, bound rubidium or cesium was essentially zero at pH less than five, increased sharply between pH 5 and 7, and tended to level off at higher pH. The present results further characterize the cation binding properties of the microsomal material.
Selective and nonselective isolation of temperature‐sensitive mutants of mouse L‐cells and their characterization
Authors: Thompson L. H. , Mankovitz R. , Baker R. M. , Wright J. A. , Till J. E. , Siminovitch L. , Whitmore G. F. 
Published: February 2005

AbstractMutants of mouse L‐cells which are temperature‐sensitive for growth have been obtained by using both selective and nonselective isolation procedures on populations treated with the mutagen nitrosoguanidine. Selective isolation was carried out by utilizing a five‐day treatment with 3H‐TdR and ara‐C as selective agents at the nonpermissive temperature. Nonselective isolation was performed by isolating 1400 clones in the absence of selective agents and then testing them for temperature‐sensitivity. From this experiment we obtained a minimum estimate of 6 × 10−3 for the frequency of mutants in the mutagentreated population. The mutants were characterized by their plating efficiencies, growth in suspension culture, and uptake of isotopic precursors of DNA, RNA, and protein. A range in phenotypes was observed, and there appeared to be some differences between the mutants obtained by the two types of isolation procedures. In uptake experiments the most marked reductions in the rates of precursor incorporation were seen with 3H‐TdR, rather than 3H‐UR or 3H‐Leu. Different mutant lines showed considerable variation in the rate of cessation of DNA synthesis as well as the time required for termination of cell division. These experiments suggest that both types of isolation procedures are feasible for obtaining temperature‐sensitive mutants having a range of phenotypes.
Proliferation of hemopoietic stem cells in culture of embryonal liver of mice
Authors: Luria Elena A. , Samoylina Nina L. , Gerasimov Y. V. , Chertkov J. L. 
Published: February 2005

AbstractThe vinblastine technique was used to demonstrate that the proliferative capacity of colony‐forming cells in organ culture of embryonal liver of mice between the first and seventeenth day of cultivation is adequately high. The relative content of CFU increases in culture with a maximum between one and two weeks.
Effect of suppression of erythropoiesis on hematopoietic stem cells in the mouse
Authors: Preisler Harvey D. , Henderson Edward S. 
Published: February 2005

AbstractErythropoiesis was suppressed in CDF1 female mice using one of three different techniques: hypertransfusion, daily injections of low doses of actinomycin D, or post‐hypobaric polycythemia. Spleens and bone marrows of these mice contained increased numbers of stem cells as determined by transplantation into lethally irradiated syngeneic mice. These stem cells were capable of producing both erythrocytic and granulocytic progeny. An increase in the number of multipotential stem cells or increases in the numbers of both unipotential granulocytic and erythrocytic stem cells is compatible with these observations and implies that hematopoietic stem cells may have a basic rate of division that is in part independent of stimuli to differentiate. The implications of these findings for the possible modification of antineoplastic drug‐induced bone marrow toxicity are discussed.
Alterations in the rate of hemoglobin synthesis during chick embryogenesis
Authors: Grinnell Frederick , Lee John C. 
Published: February 2005

AbstractThe rate of synthesis of different hemoglobin (Hb) species — embryonic, primitive, definitive, and adult — in the circulating red cells of the chick embryo have been measured. On the fifth day of chick embryogenesis, there is a marked decrease in the capability of these red cells to synthesize Hb. The rates of synthesis of embryonic and primitive Hb decrease markedly compared to that of definitive and adult Hb. On the fourth day of embryogenesis nucleic acid synthesis drops sharply in these cells. These decreases in metabolic activity preceed the disappearance of the primitive erythrocyte from the chick embryo circulation. It appears that the primitive cell line is specifically shut off with respect to its metabolic activities and possibly destroyed at this time.
The effect of multivalent cations on the membrane potential of the ehrlich ascites tumor cell
Authors: Smith Thomas C. , Mikiten Terry M. , Levinson Charles 
Published: February 2005

AbstractThe effect of di‐ and trivalent cations on the membrane potential of the Ehrlich ascites tumor cell has been investigated using micro‐electrode techniques. In solutions free of multivalent cations the average membrane potential for 46 cells was 8.3 ± 0.5 mv (SE). However, the potentials were not stable and decayed with a half‐time of about six seconds. Addition of Ca++ decreased the rate of decay and concomitantly increased the membrane potential. The magnitude of these effects was a function of the Ca++ concentration. At the optimum concentration (2 mM), the half‐time of decay was increased to 12 seconds and the membrane potential was raised to 17.8 ± 1.7 mv (SE). The related alkaline‐earth cations, Sr++, Ba++ and Mg++ had similar effects on both the stability and magnitude of the membrane potential. The effect of La+++, which was qualitatively similar to that of the divalent cations, was also concentration dependent. However, 100‐fold lower concentrations were adequate to achieve comparable effects. Moreover, membrane potentials were stable for up to ten minutes in La+++‐containing solutions. Variations in intracellular Cl− content induced by temperature changes were paralleled by changes in membrane potentials. However, the potentials were not those expected for a simple Cl− electrode.
Response of multipotent (CFU) and granulocyte (diffusion chamber assay) progenitor cells and differentiating cells of murine haematopoietic tissues to a perturbation of the steady state
Authors: Breivik Harald 
Published: February 2005

AbstractRegulation of haematopoiesis was investigated by studying the response of haematopoietic tissues of mice to a perturbation of the steady state by vinblastine (VLB). Progenitor cells were quantified ly limiting dilution analysis of diffusion chamber cultures of haematopoietic cells and by the spleen colony technique. The diffusion chamber technique appears to assay granulocyte progenitor cells and those multipotent progenitor cells that become committed to granulopoiesis during chamber culture. The spleen colony technique probably assays multipotent progenitor cells.Decaying oscillatory responses to VLB were observed for progenitor cells as well as for differentiating cells in bone marrow. The period lengths of the diffusion chamber progenitor cell oscillations might indicate that these were induced by humoral feedback signal(s) from nonproliferative granulocytes. The oscillations of the multipotent progenitor cells of bone marrow were less pronounced and were earlier damped than those of the granulocyte progenitor cells. This may support the hypotesis that multipotent progenitor cells are regulated by more efficient mechanisms, which may depend on short range cell‐cell interactions rather than long range humoral regulators.
Sialic acid masked membrane antigens of clonal functional glial cells
Authors: Herschman H. R. , Breeding J. , Nedrud J. 
Published: February 2005

AbstractAntisera have been prepared to clonal cultured rat astrocytic cells (C6 cells) and clonal human astrocytic cells (CHB4 cells). When cultured glial cells are grown in the presence of neuraminidase the serological activity of the cell membrane with homologous antiserum is increased extensively. A similar activation of serological activity can be effected by incubating washed harvested cells with this enzyme. Membrane bound N‐acetyl‐neuraminic acid is extensively reduced by either incubation. The activity responsible for promoting the enhanced serological activity co‐chromatographs and co‐electrophoreses with neuraminidase. Proteolytic digestion, unlike neuraminidase treatment, was unable to enhance the serological activity of cultured glial cells.
Stimulation of rabbit erythroblast multiplication and maturation in vitro by blood leukocytes: Cytological observations. III. Studies on erythropoiesis
Authors: Borsook Henry , Jiggins Susan , Wilson Rosina T. 
Published: February 2005

AbstractBlood leukocytes incubated in vitro with rabbit‐marrow cells induced a several‐fold increase in basophilic erythroblasts and smaller increases in acidophils and reticulocytes. The main effect was nearly complete in one hour at 37°. Erythropoietin augmented the leukocyte effect; anti‐erythropoietin inhibited it with or without erythropoietin. The erythroblast increase came entirely from the marrow cells; the precursor cell class has not been identified, except that division of pre‐existing basophils appears to be excluded. Autologous and homologous leukocytes were about equally effective.A method is described of measuring on stained smears changes in relative concentrations of different classes of cells induced experimentally. A method of preparing highly concentrated peripheral blood leukocytes is described.
Competitive in vivo proliferation of foetal and adult haematopoietic cells in lethally irradiated mice
Authors: Micklem H. S. , Ford C. E. , Evans E. P. , Ogden D. A. , Papworth D. S. 
Published: February 2005

AbstractThe relative proliferative capacity of haematopoietic cell populations derived from 22‐week‐old adult bone marrow and 14–18 day foetal liver has been studied in lethally irradiated syngeneic recipients by means of chromosome markers. Although starting at a disadvantage in terms of the number of colony‐forming units (stem cells) injected, the foetal liver‐derived populations steadily increased their relative numbers in the myeloid and lymphoid tissues over a period of several weeks until a plateau was reached. It is suggested that stem cells in foetal liver have, on average, a higher intrinsic capacity for self‐renewal than do those in bone marrow, and that this capacity falls to the adult level within about ten weeks of transfer.
Hypoplasia of the bone marrow in rats following removal of the parathyroid glands
Authors: Rixon R. H. , Whitfield J. F. 
Published: February 2005

AbstractRemoval of the parathyroid glands caused a marked and permanent lowering of the mitotic activity in rat bone marrow, which was followed by a pronounced decline (ca. 40%) in the size of the marrow's nucleated cell population. These changes occurred only when the hypocalcemia induced by the lack of parathyroid hormone (PTH) was maintained by feeding the animals a calcium deficient diet. Since the overall marrow hypoplasia was almost entirely due to strikingly large reductions (ca. 70%) in the size of the erythroid and lymphoid subpopulations, it is concluded that PTH and calcium are major physiological regulators of the proliferation of erythroid and lymphoid cells.
Electrogenesis of embryonic chick skeletal muscle cells differentiated in vitro
Authors: Kano Masaakira , Shimada Yutaka , Ishikawa Koichi 
Published: February 2005

AbstractElectrogenesis of embryonic chick skeletal muscle cells differentiated in monolayer cultures was investigated. Muscle fibers in vitro generate spike potentials similar to those of fibers in vivo. However, other responses, plateaux resembling those in heart muscle, are also elicited. These results suggest that a functional differentiation exists in cultured muscle fibers.
Independent regulation of cytochromes and glycolytic enzymes in human fibroblasts
Authors: Pious Donald A. , Susor Walter A. , Benson Robert W. , Rutter William J. 
Published: February 2005

AbstractGrowth of cultured human fibroblasts in low oxygen resulted in reciprocal changes in the levels of cytochrome oxidase and several glycolytic enzymes. After five days' growth in low oxygen, cytochrome oxidase specific activity fell to 40% of the level of control cultures, while lactic dehydrogenase (LDH), aldolase, and triose phosphate dehydrogenase (TDH) levels were increased by 2‐ to 3‐fold. These changes were accompanied by a change in the LDH isoenzyme pattern resulting from an increase in the proportion of LDH A subunits; the aldolase electropherogram was unchanged. When fibroblasts were grown for five days in medium containing chloramphenicol, cytochrome oxidase specific activity fell to 10% of control values, but LDH, aldolase and TDH specific activities and LDH and aldolase electropherograms did not differ significantly from controls. These findings are interpreted to indicate that the increased accumulation of LDH, aldolase and TDH induced by low oxygen is not mediated by the rate of accumulation of cytochrome oxidase.
Synthesis of the small molecular weight monodisperse nuclear RNA's in contact‐inhibited cell cultures
Authors: Rein Alan , Penman Sheldon 
Published: February 2005

AbstractThe small molecular weight monodisperse nuclear RNA's are synthesized in contact‐inhibited cultures of 3T3 cells. The level of synthesis of these RNA's, and of ribosomal and transfer RNA's, appears to be only 8–20% of that observed in growing cultures. The synthesis of all of these relatively stable RNA species may thus be coordinately controlled.
Lymphopoiesis in the rat. I. The effect of pool size on lymphocyte production
Authors: Vaughan W. P. , McGregor D. D. 
Published: February 2005

AbstractA method is described for measuring lymphopoiesis that enables the production of recirculating and non‐recirculating small lymphocytes to be estimated simultaneously. Using this technique, experiments were undertaken to determine whether the production of recirculating cells is influenced by the number present in the recirculating lymphocyte pool. The results suggest that neither a massive lymphocyte transfusion nor depletion of the pool by whole body irradiation or chronic lymph drainage affect the rate at which recirculating small lymphocytes are generated.
Lymphopoiesis in the rat. II. The effect of thymectomy
Authors: Vaughan W. P. , McGregor D. D. 
Published: February 2005

AbstractLymphopoiesis with respect to recirculating and non‐recirculating small lymphocytes was measured simultaneously in rats thymectomized as adults. Removal of the thymus at four to five weeks of age had a profound inhibitory effect upon the production of recirculating cells, whereas the formation of non‐recirculating lymphocytes was only slightly depressed. Thymectomy had approximately the same impact of lymphopoiesis as thymectomy and exposure of the animal to a large dose of whole body X‐ and γ‐irradiation. The latter finding, and the failure of a thoracic duct cell transfusion to augment lymphocyte production, accord with the view that the thymus is the principle intermediate source of recirculating small lymphocytes in the normal, unstimulated animal.
Volume changes of mammalian cells subjected to hypotonic solutions in vitro: Evidence for the requirement of a sodium pump for the shrinking phase
Authors: Rosenberg Howard M. , Shank Brenda Buckhold , Gregg Earle C. 
Published: February 2005

AbstractA Coulter‐orifice pulse‐height analyzer system was used to measure volume spectra of mammalian cells in suspension at different times after the addition of an equal volume of water. In appropriate hypotonic medium, cultured mammalian cells rapidly increase in volume and then shrink, more slowly, approaching their initial volumes within 20 to 30 minutes at 37.5°C. The shrinking phase was found to be reversibly inhibited by ouabain and inhibited in both K+‐free and Na+‐free solutions; neither choline+ nor Li+ could substitute for extracellular Na+ in supporting the shrinking phenomenon but Rb+ and Cs+ were fairly good substitutes for K+.Under conditions similar to those with which the shrinking phenomenon was observed with cultured cells, it was not found with either human or mouse red blood cells.Two methods were used to determine intracellular Na+ and K+ content in osmotically shocked cells and in unshocked controls. An isotope equilibration method was employed with L5178‐Y mouse lymphoblasts and a chemical determination by flame photometry was used with Ehrlich ascites tumor cells. The K+ content was significantly reduced and the Na+ content was unchanged or somewhat increased in cells which had returned to their original volumes in hypotonic medium. The K+ content was even more reduced but the Na+ content was greatly increased in cells which were osmotically shocked in the presence of ouabain.
Studies on the bone marrow colony stimulating factor (CSF): Relation of tissue CSF to serum CSF
Authors: Sheridan J. W. , Metcalf D. 
Published: February 2005

AbstractFluctuations in the colony stimulating factor (CSF) content of submaxillary salivary gland, lung, kidney and spleen were studied in male C57BL mice which had been subjected to a variety of stimuli (endotoxin, x‐irradiation or polyadenylic‐polyuridylic acid complex) that caused elevations of the serum CSF. The temporal relationships and magnitudes of the rises in CSF were complex and differed from tissue to tissue according to the stimulus used. In the tissues examined not only was the measurable CSF content in each case found to equal or exceed the prestimulatory levels, but in some cases distinctly different forms of CSF were observed as shown by differences in the zone sedimentation, electrophoretic, and calcium phosphate binding characteristics of the material. The patterns of response to the stimuli investigated suggested that tissue injury either directly, or indirectly via the release of various cellular constituents, might mediate the release of CSF by various widely disseminated and/or differing cell types.
Nucleoside deaminase activity during the recovery of X‐irradiated, bone marrow‐protected mice
Authors: Basch Ross S. , Malathi V. G. , Silber Robert 
Published: February 2005

AbstractIncreased activity of the enzyme nucleoside deaminase is found in the spleens of mice protected from lethal whole‐body irradiation by transfusion of isogenic bone marrow cells. As few as 10,000 nucleated bone marrow cells produce a significant elevation in enzyme level. This increase precedes any detectable increase in hemoglobin synthesis and is temporarily associated with an increase in protein synthesis during the early stages of recovery. Hypertransfusion of the irradiated, protected mice eliminates most of the stimulus to erythroid differentiation and prevents the increase in nucleoside deaminase. The present studies indicate that this enzyme is present in a differentiated red cell precursor not found in the normal stem cell population.
Circadian rhythms in the mitotic index of the basal epithelium and in the uptake rate of 3H‐thymidine by the tongue of the rat
Authors: Gasser Raymond F. , Scheving Lawrence E. , Pauly John E. 
Published: February 2005

AbstractCircadian rhythms are demonstrated in the tongue of adult rats for both the mitotic index of the basal epithelium and the uptake rate of injected 3H‐thymidine by the tongue tip. The animals were entrained to a light‐dark cycle for four weeks prior to the experiments with the light phase extending from 0600 to 1800 hours (CST). The daily fluctuation is approximately 300% for the mitotic index and 185% for the uptake rate of 3H‐thymi‐dine. The highest mitotic index occurs at 1100, and the highest uptake of 3H‐thymidine occurs four hours earlier at 0700. The least activity for both parameters occurs during the first part of the dark span of the light‐dark cycle. Estimates of several other rhythmic parameters are determined by a computerized method.
Relationship between cytoagglutination and saturation density of cell growth
Authors: Weber Joseph 
Published: February 2005

AbstractThe agglutination with concanavalin A and wheat germ agglutinin of the established malignant cells, HEp 2, KB, HeLa, TDB‐3, HTC and RV 3T3, and of the putatively normal cells, BHK 21, 3T3 and Wi‐38 was examined as a function of their saturation densities in culture. A positive correlation between the saturation density of the cell lines and the capacity to agglutinate was demonstrated. Incubation for 15 minutes with 1.25 mg/ml of trypsin converted non‐agglutinating and poorly agglutinating cells into agglutinable ones, while leaving the highly agglutinating lines largely unchanged. The magnitude of change in agglutination after trypsin treatment correlated inversely with saturation density. Although the extent of agglutination varied with the saturation density, the agglutinability of a particular line remained relatively unchanged at different cell densities.
Selective hybrid cell formation by human lymphoid cells
Authors: Parkman Robertson , Hagemeijer Ann , Merler Ezio 
Published: February 2005

AbstractSubpopulations of human lymphoid cells are capable of spontaneously fusing with fibroblasts of human or murine origin to form human‐human or human‐mouse hybrid cells. These cells were present in thymus, spleen, and bone marrow. After fractionation on discontinuous bovine serum albumin gradients, the cells were found in the less dense layers of the gradient. Cells of fetal origin, except for bone marrow, fused spontaneously at a higher rate than those of adult origin. The highest rate of fusion was found with adult bone marrow cells. These lymphoid cells appear to be “thymus‐derived” cells.
Nucleotide pools of novikoff rat hepatoma cells growing in suspension culture. IV. Nucleoside transport in cells depleted of nucleotides by treatment with KCN
Authors: Plagemann Peter G. W. , Erbe John 
Published: February 2005

AbstractIncubation of Novikoff rat hepatoma cells in glucose‐free basal medium containing 2 mM KCN results in a rapid and almost complete loss of uracil and adenine nucleotides. By following the fate of radioactivity from 3H‐nucleoside pulse‐labeled cells during incubation with KCN it was shown that the nucleotides are degraded to nucleosides and bases which are released into the culture fluid. Depletion of the cells of nucleotides by incubation with KCN allows a direct analysis of the kinetics of uridine transport into the cell, since KCN‐treated cells fail to phosphorylate uridine. Uridine uptake follows normal Michaelis‐Menten kinetics with an apparent Kn of about 50 μm at 18°C. Uptake is by facilitated diffusion since it does not require energy and uridine is not transported against a concentration gradient. The effects of KCN are largely prevented by the presence of 10 mM glucose in the medium. They are also rapidly reversed by resuspending the cells in fresh medium without KCN. Upon removal of KCN, the cells rapidly regenerate their nucleotide pools and resume growth at the normal rate.