bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of ATP, EDTA and EGTA on the simultaneous binding of Na, K, Mg and Ca by rat liver microsomes
Authors: Sanui Hisashi , Pace Nello 
Published: February 2005

AbstractIn the presence of Na, K, Mg and Ca at physiological pH, complexing agents can affect cation binding by rat liver microsomes in a manner not always readily predictable simply from a knowledge of individual formation constants. Increasing concentrations (0 to 20 mM) of the strong nonbiological complexing agent, ethylenediaminetetraacetate (EDTA), produced a sharp decrease almost to zero in bound Ca, an increase to a high plateau in bound Na and K and an initial increase followed by a sharp decrease in bound Mg. Increasing concentrations of the Ca‐preferring analogue of EDTA, ethylene bisglycol (β‐aminoethylether) tetraacetate (EGTA), produced similar changes except that bound Mg increased and remained elevated, indicating that this agent complexes Mg very weakly at physiological pH. The biological complexing agent, adenosine triphosphate (ATP), caused a gradual rectilinear and parallel decrease in bound Mg and Ca and a concomitant and parellel increase in bound Na and K at about 4°C and pH 6.4. Results with EDTA and EGTA suggest, however, that under different conditions, enhancement by ATP of divalent cation binding may be possible. Reactions of this nature may be of significance in ATP stimulated divalent cation uptake by subcellular particles.
Measurement of the electrical potential difference across the membrane of the ehrlich mouse ascites tumor cell
Authors: Aull Felice 
Published: February 2005

AbstractThe electrical potential difference (PD) across the membrane of the Ehrlich mouse ascites tumor cell has been measured with intracellular microelectrodes. The mean for 111 cells in control Ringer solution was − 11.2 mV ± 0.29 (SE), interior negative. When sulfate replaced chloride in the external medium the PD fell to − 2.8 mV if measured as soon as possible after mixing the cells with a sulfate medium, but when nitrate replaced chloride the PD fell only to − 8.5 mV. Cells equilibrated in nitrate had the same PD as those in control Ringer. These results indicate that the PD is sensitive to changes in the external chloride concentration and that nitrate can substitute for chloride electrically. However, since the PD for chloride, based on the Nernst equation and calculated on the basis of 70% exchangeability of cell chloride, is three times greater than the measured PD, it is hypothesized that sodium contributes significantly to the membrane potential in addition to chloride. On the other hand, potassium does not influence the PD to any great extent.
Ribonuclease of cultured mammalian cells
Authors: Flanagan John F. 
Published: February 2005

AbstractKB cell ribonuclease has been purified 260‐fold and the fundamental properties have been studied. Though the enzyme is concentrated in the lysosomal fraction, appreciable quantities are present in the cell sap and nuclear fractions. Comparison of the optimal temperature and pH for activity, and the heat stability of enzyme from these three fractions suggests that only one species of this enzyme exists in these cells. The enzyme behaves as an endonuclease, cleaving synthetic pyrimidine polynucleotides to smaller oligonucleotides with cyclic 2′:3′ end‐groups. The final product is pyrimidine nucleoside 3′ monophosphate. Polyadenylic acid is not hydrolyzed. Of the properties examined in this study only two differences were noted between KB cell and pancreatic ribonuclease. KB cell enzyme acts optimally at pH 6 as opposed to an optimum at pH 7 to 8 for pancreatic enzyme. In addition ribonuclease from KB cells is definitely less stable to heating at 100°C than is the enzyme isolated from pancreas.
Variable duration of DNA synthesis in mammary gland cells during pregnancy and lactation of C3H/He mouse
Authors: Banerjee M. R. , Walker Ruby J. 
Published: February 2005

AbstractLabeling index as well as the duration of DNA synthesis in alveolar cells of C3H mouse mammary gland at various stages of development was determined by autoradiographic methods. Labeling index of the alveolar cells is highest during pregnancy followed by a marked decrease in the lactating gland. The labeling index of the prelactating cells is significantly reduced after the same cells are transplanted into virgin females. Duration of DNA synthesis in the alveolar cells at eighth and fifteenth day of pregnancy is 14.1 and 8.2 hours respectively. During early lactogenesis, duration of DNA synthesis in the mammary alveolar cells was estimated as 8.5 hours. There is a 2–3 fold increase of the DNA replication time (21.5 hours) in the outgrowth cells of 15 day prelactating tissue after transplantation into virgin host.A possible role of the hormones of pregnancy, estrogens and progesterone for stimulation of DNA synthesis in the prelactating tissue has been discussed. It has been suggested that the marked inhibition of DNA synthesis in the lactating tissue may be due to the increased stimulation of the same tissue by endogenous adrenocorticoid hormones. Variability of the duration of DNA synthesis (8.5–21.5 hours) in alveolar cells indicates that in mouse mammary gland, DNA synthetic time is not an unadjustable process. Control of DNA synthesis in mouse mammary gland cells by exogenous 17‐β‐estradiol and progesterone has been previously reported (Bresciani, '65). It is suggested that the same hormones of endogenous origin also may influence the duration of DNA synthesis and cell proliferation during mammogenesis.
Effects of helium group gases and nitrous oxide on hela cells
Authors: Bruemmer J. H. , Brunetti B. B. , Schreiner H. R. 
Published: February 2005

AbstractThe helium group gases and nitrous oxide at superatomospheric pressures depress multiplication of HeLa cells in monolayer cultures. The effectiveness of these gases in eliciting the pressure‐dependent response follows the order N2O, Xe > Kr > Ar > > Ne and He. The response correlates with lipid solubility of the gases.Depression of growth by 4.2 atm Xe is reversible after exposure for one and two days. Cultures exposed to 7.2 atm Xe show irreversible damage including cytoplasmic vacuolization.Cell attachment is strongly inhibited by Xe; 36% of the cell inoculum were not attached after 24 hours. Affinity for hydrophobic sites in the cell is suggested as determining the order of effectiveness of the gases in evoking the response.
Dynamic adhesion and separation of cells in vitro I. Mathematical analysis of the experimental system
Authors: Blumenson Leslie E. 
Published: February 2005

AbstractThe contact interaction between cells and thewalls of microchambers through which the cells are passing are quantitated in terms of parameters which are estimated from macroscopic experimental data. For this purpose, an analysis is made of the internal geometry of glass bead‐columns. A mathematical model is presented which describes the passage of cells down the column. This model relates the temporal pattern of the number of cells entering and leaving the bead‐column to the “dynamic adhesive” properties of a cell as it passes through a microscopic section of the bead‐column.
Erythrocyte membrane sulfhydryl groups and the active transport of cations
Authors: Rega Alcides F. , Rothstein Aser , Weed Robert I. 
Published: February 2005

AbstractParachloromercuribenzenesulfonate (PCMBS) has two opposing effects on the influx of Rb+ into red blood cells. The ouabain‐insensitive component, indicative of passive permeability of the membrane to cations, is increased whereas the ouabain‐sensitive or active transport component is inhibited. The increased passive permeability is paralleled by the action of PCMBS on net K+ efflux into a K+‐free medium. Inhibibition of active transport of Rb+ is paralleled by the inhibitory action of PCMBS on net Na+ efilux from Na+‐rich cells. Both effects are reversed rapidly by the penetrating sulfhydryl compound, cysteine, and considerably more slowly by the non‐penetrating sulfhydryl compound, ovalbumin. Measurements of PCMBS binding and of elution in the presence of cysteine and albumin indicate that only a fraction of the total sulfhydryl groups of the membrane is involved in either the effect on permeability or transport, and that the affected groups are located within the interior of the membrane.
The induction of multinuclearity in agitated and in aging cultures of Acanthamoeba sp. neff
Authors: James T. E. , Byers T. J. 
Published: February 2005

AbstractUnagitated cultures of Acanthamoeba in the logarithmic growth phase have been observed to consist of over 99% mononucleates and less than 1% multinucleates. A small increase in the relative numbers of multinucleates occurs as the culture age and conditions for growth become limiting. A large increase in the proportion of multinucleates occurs during logarithmic growth, if the cultures are agitated by shaking or by the bubbling from a stream of air. After an initial increase and until the end of logarithmic growth, the numbers of multinucleates in the agitated cultures are maintained at a constant fraction of the total population. Proportions of multinucleates as high as 25% are observed during this period. A second increase in the relative numbers occurs as conditions for growth become limiting. Under these conditions, the multinucleates may exceed 50% of the total population. The factors inducing multinuclearity as well as the kinetics of the mononucleate and multinucleate accumulation curves are discussed.
The stimulation of amino acid incorporation into the protein of unfertilized sea urchin eggs by γ‐irradiation
Authors: Rustad Ronald C. 
Published: February 2005

AbstractControl and γ‐irradiated sea urchin (Arbacia punctulata) eggs were incubated with H3‐leucine. No incorporation of the amino acid into the proteins of most unirradiated eggs was detectable by autoradiography. All irradiated eggs incorporated the amino acid and the amount of autoradiographic labelling varied greatly from cell to cell.
Electrophoretic studies of muscle proteins. I. Complex formation between delta protein and F‐actin
Authors: Amberson Willia R. , Bauer Adelia C. 
Published: February 2005

AbstractComplex formation between delta protein and F‐actin has been demonstrated by electrophoretic technique. The high turbidity of F‐actin solutions has made it necessary to work at low concentrations of this protein (0.8 to 1.6 mg/ml). Delta protein concentrations were four to six times greater. At higher concentrations all F‐actin was bound to delta protein, on both limbs. The combination ratio was about 1:1 by weight. We call this complex “delta‐actin.” When the complex formed there was a slight fall in viscosity, indicating side‐by‐side union, but the turbidity greatly increased. The mobility of delta‐actin was always less than that of free F‐actin and sometimes also less than that of free delta protein.We earlier reported that delta protein is probably a polymer of tropomyosin. Its sedimentation constant (4.4 to 6.0 S) is higher than the of any other form of tropomyosin so far described. It may be the native molecule, its structure preserved by our relatively simple method of extraction and purification.The filaments of the I band may be composed of delta‐actin. Since delta protein also forms a complex with myosin the filaments of the A band may be composed of delta‐myosin. Delta protein may be a structural component which, in addition to other activities, may direct the building of both filament arrays and strengthen them.
Heterolysosome formation in mouse liver
Authors: Mego John L. , McQueen J. Donald 
Published: February 2005

AbstractWhen formaldehyde‐treated 131I‐albumin was injected into mice, the total liver radioactivity did not change significantly from 5 minutes to 60 minutes after injection. There was a progressive increase with time in the amount of radioactivity associated with liver particles which could be released by osmotic shock; the quantity of material tightly bound to particles, but not releasable by osmotic shock, did not change. At five minutes after injection the liver particles did not release acid‐soluble radioactivity into the medium when incubated at 37°. These particles contain the injected protein in osmotically releasable form not associated with proteolytic enzymes and therefore correspond to phagosomes. At 10, 30 or 60 minutes after injection, the particles degraded the protein at similar rates but the activity ceased after 90 minutes incubation when only 50 to 60% of the osmotically releasable material was hydrolyzed. This cessation of activity was shown to be due to a thermal disruption of the particles during incubation.
Spedtral properties of a pigmented body in Hymenomonas sp.: An extra‐chloroplast organelle containing chlorophyll
Authors: Olson Rodney A. , Jennings William H. , Allen Mary Belle 
Published: February 2005

AbstractIn the chrysomonad Hymenomonas, a lamellar organelle of undefined function described previously in electron micrographs, is shown to be highly pigmented by absorption and fluorescence light microscopy. Absorption spectra of the lamellar organelle and the chloroplasts of Hymenomonas are presented. In comparison with the chloroplast the lamellar body appears to have an equal concentration of chlorophyll α and nearly three times the concentration of the 490 nm absorbing carotenoid. Fluorescence in the organelle is initially red as in the chloroplast; this is quickly replaced by an intense yellow emission. The rate at which the red fluorescence is replaced by the yellow is oxidation dependent and is quite rapid in the high intensity of the exciting light required for fluorescence micrographs. Possible roles of the organelle in cell metabolism or photochemistry which are considered and evaluated include: photosynthetic organelle, coccolithogenic organelle, symbiont and lysosome.
Tritiated thymidine effects on DNA, RNA, and protein synthetic rates in synchronized L‐cells
Authors: Krause Margarida O. 
Published: February 2005

AbstractExponentially growing L‐cells were synchronized by the double thymidine‐block method and exposed to high specific activities of tritiated thymidine. DNA, RNA, and protein synthetic rates were measured through one cell cycle with 1‐hour pulses of the appropriate C14‐labelled precursors. Equivalent doses of tritiated water were substituted for tritiated thymidine in some experiments. Total amounts of DNA and histones per nucleus were determined photometrically in Feulgen and fast‐green stained cells.It was observed that incorporated tritiated thymidine has an effect distinct from that of tritiated water and that it enhances the incorporation of the precursors at specific stages of the cell cycle, to a degree roughly proportional to the dose. Photometric data indicated an increase in DNA net synthesis and a metabolic instability of histones in the H3‐thymidine‐treated cells, resulting in higher DNA:histone ratios.
Effects of D2O on the mechanism of pigment dispersal in the melanocytes of Fundulus heteroclitus: A pressure‐temperature analysis
Authors: Marsland Douglas , Meisner Donald 
Published: February 2005

AbstractThe melanocytes of isolated fish scales (Fundulus heteroclitus) immersed in 0.1 M aqueous KCl solution and in deuterated KCl solutions, in which 50–70% of the H2O was replaced by D7O, were observed at 300× magnification while they were subjected to increasing hydrostatic pressure, raised in increments of 1,000 psi in the range up to 16,000 psi. In one series of experiments the temperature was maintained at 20°C (± 0.2°), whereas in the other it was kept at 25°C (± 0.2).Initially, all the melanocytes in the KCl media displayed a contracted, or punctate, form. With increasing pressures, gradually, expansion, or pigment granule dispersal, occurred but the degree of expansion at a given pressure depended upon the percentage of deuteration and the temperature. At 20°C in aqueous medium, total expansion, in which the pigment extended all the way out into the peripheral tips of melanocyte branches, occurred at 8,000–9,000 psi. At lower pressure, the intermediate values, expressed as a percentage of the total, fell along a smooth, slightly sigmoid curve. In the deuterated media, similar curves were obtained, but the pressure levels required to produce a given degree of expansion were significantly higher. Thus, maximum expansion required the imposition of 14,000 psi in the 50% D2O medium and of 16,000 psi in the 70%. Upon decompression, at the end of each experiment, the melanocytes quickly contracted, reaching a completely punctate form within 3–4 minutes.Similar relationships were found at 25°C, except that all the pressure values were significantly higher than those at 20°C. In fact the values for 25°, with 50% deuteration, were very similar to those for 20°, with 70% D2O.The evidence tends to confirm conclusions, previously submitted, namely, that, as expansion occurs, the cytoplasm of the unicellular pigmentary effectors of the fish undergoes a progressive process of solation and that contraction involves a reestablishment of the original firm gel structure. Thus the well known solational effects of high pressure tend to be counteracted by agencies, such as increasing deuteration and temperature, which are known to foster protoplasmic gelations generally.
Nucleotide action on spontaneous electrical activity of calcium deficient nerve
Authors: Kuperman Albert S. , Okamoto Michiko , Gallin Elaine 
Published: February 2005

AbstractIn concentrations having no effect on the evoked alpha‐A fiber spike, adenosine triphosphate (ATP), adenosine monophosphate (AMP) and several other nucleotides produced antagonism of spontaneous impulses in isolated desheathed frog nerve soaked in Ca free solution. ATP was only slightly more potent than AMP, indicating that high‐energy phosphate bonds and Ca complexing are not important for stabilizing action. Furthermore, sub‐effective concentrations of Ca potentiated the stabilizing action of ATP to a minimal degree and that of AMP not at all, suggesting a direct action of the nucleotide per se rather than a Ca‐nucleotide complex. Ca45 washout experiments showed that the nucleotides did not depress efflux of Ca from nerve axons but, in fact, caused release of Ca. It was proposed that nucleotide stabilization is associated with replacement of nucleotide lost from the excitable membrane into the Ca free medium.
Stability of division‐related protein and nucleic acid fractions in synchronized Tetrahymena
Authors: Byfield John E. , Scherbaum Otto H. 
Published: February 2005

AbstractThe kinetics of RNA synthesis have been studied under various growth conditions using synchronized Tetrahymena pyriformis GL. The curves obtained are approximately linear in growth‐supporting media but vary under other circumstances. The presence of amino acids in the medium stimulates RNA synthesis in Tetrahymena as it does in bacteria. Since these induced variations do not influence the essential features of the pre‐cytokinetic period it is inferred that fluctuations in the rate of RNA synthesis described by others are probably not essential features of temperature‐induced synchrony. In addition, the translational stability of division‐related templates at synchronizing temperatures has been investigated. The synthesis of proteins necessary for cytokinesis is shown to be greatly reduced under conditions simulating a heat‐shock. Inhibitor studies using cycloheximide indicate that protein synthesis is required longer into the cytokinetic phase than had previously been thought. Collectively the data are all compatible with the hypothesis that synthesis of division‐related proteins is drastically reduced in heat‐shocked Tetrahymena and that the basis for this reduction is hydrolysis of template RNA without concurrent translation.
Patterns of resistance to 2‐deoxy‐D‐glucose in pig kidney cells
Authors: Bailey Philip J. , Harris Morgan 
Published: February 2005

AbstractVariants resistant to 2‐deoxy‐D‐glucose have been isolated from a clonal line of pig kidney cells by serial cultivation in the presence of inhibitor. Hexokinase activity may be affected directly in this system, since the oxidation of glucose to 6‐phosphogluconate by extracts from sensitive and resistant cells is blocked by the addition of 2‐deoxy‐glucose to the reaction mixture. This blockage was removed by the addition of glucose‐6‐phosphate to the system, but not by ATP. Resistant cells were found to accumulate significantly less 2‐deoxyglucose‐6‐phosphate than sensitive cells. The rate of phosphorylation of 2‐deoxyglucose, however, was higher in extracts from the resistant line. Alkaline phosphatase does not account for the reduced level of 2‐deoxyglucose‐6‐phosphate since this enzyme is not detectable in sensitive or resistant pig kidney cells. Increased acid phosphatase activity was observed in resistant cells, but extracts with high acid phosphatase activity proved incapable of hydrolyzing either 2‐deoxyglucose‐6‐phosphate or glucose‐6‐phosphate. In comparative growth studies, cells resistant to 2‐deoxyglucose proliferated more extensively than sensitive cells in a low glucose nutrient. They removed glucose more effectively from this medium, and were less stimulated by the addition of intermediates from the tricarboxylic acid cycle. The evidence suggests that resistance to 2‐deoxyglucose in the cells under study may be based on the ability of the resistant cells to proliferate at concentrations of glucose too low to support the growth of sensitive cells.
The repopulating potential and differentiation capacity of hematopoietic stem cells from the blood and bone marrow of normal mice
Authors: Lewis Jerry P. , Passovoy Mitchell , Freeman Mary , Trobaugh Frank E. 
Published: February 2005

AbstractUsing the hematopoietic colony technique, we have investigated the repopulating potential of bone marrow cells and leukocytes of blood from normal mice and have demonstrated that the frequency of hematopoietic stem cells in bone marrow is 50 to 150 times that of stem cells in the circulating blood. The differentiation capacity of these stem cells has also been examined. Results of comparative studies of the serial sections of hematopoietic colonies formed from marrow and blood leukocytes indicate that the differentiation capacity of stem cells from marrow and blood is similar, and that at least 80% of these cells differentiate along a single cell line. Thus, peripheral blood stem cells can effect a complete hematopoietic graft, establishing in the host, donor red cells, granulocytes, and platelets.The possibility that blood leukocytes may serve as a potential source of stem cells for hematopoietic transplants has been considered. Although blood contains stem cells, their frequency is so low as to make it unlikely that they would become a useful source of precursor cells for transplantation purposes.
The influence of progressive growth on the specific catalase activity of human diploid cell strains. II. Effect of cellular genotype: A heterozygous strain
Authors: Pan Yue‐Liang , Krooth Robert S. , Takahara Shigeo 
Published: February 2005

AbstractHuman diploid cell strains develop progressively higher levels of specific catalase activity as they grow. Following subculture activity falls again. A diploid cell strain heterozygous for the gene for acatalasia I (acatalasemia) was found to develop specific catalase activity at proportionately the same rate as normal cell strains. Yet the mutant gene reduced the absolute level of specific catalase activity which the culture attained at any given point in time. In this respect the heterozygous acatalasia I strain resembles the homozygous acatalasia II strain previously reported.