bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cellular uptake of 3H‐actinomycin D in the hematological tissues and liver of the mouse
Authors: Cohen Natalie S. 
Published: February 2005

AbstractActinomycin D(AM), an inhibitor of DNA‐dependent RNA synthesis, produces a reversible cessation of red blood cell production. This study examines the in vivo cellular uptake of 3H‐AM in the hematological tissues and livers of B6D2F1 mice. 3H‐Am (sp. act. = 2.97 to 4.20 C/mmole) was given IV at a dose of 4.0 to 5.7 μg (14 μc) per mouse. Spleen, bone marrow, blood, and liver samples were taken for autoradiography at post‐injection times of five minutes to 67 hours.We have confirmed the rapid in vivo cellular uptake of AM; substantial quantities of the drug were in the nuclei within five minutes of IV administration.Not all cell types became labeled. Erythroid, hepatic, lymphoid, and reticulo‐endothelial (RE) cells and monocytes took up the label, whereas labeling of granulocytic elements was doubtful.Most heavily labeled were liver cells (highest mean grain count = 110.1) and splenic RE(19.1) and erythroid (16.1) cells. Erythroid cells in the spleen were more heavily and more rapidly labeled than those in the bone marrow.All nucleated erythroid maturational stages, in both the spleen and the bone marrow, were labeled, even at five minutes.The time course of erythroid and hepatic labeling was quite different. Whereas early erythroid cells required six hours to become 100% labeled, liver cells were 100% labeled at five minutes and loss of hepatic labeling began as early as 15 to 30 minutes.
Effects of phenethyl alcohol on yeast cells
Authors: Burns Victor W. , Wong D. 
Published: February 2005

AbstractAn investigation of the physiological effects of phenethyl alcohol (PEA) on exponentially growing yeast cells is reported. RNA, DNA, protein and aminoimidazole ribotide syntheses and glucose uptake and incorporation are inhibited by PEA at concentrations of 0.1% to 0.3%. Two classes of response curves are found and the sensitivities of processes in each class to PEA differ. Glucose incorporation and RNA synthesis are the most sensitive processes in their respective classes. The effects of PEA at 0.3% or less are largely or completely reversible. It is deduced that PEA inhibits intracellular processes as well as the cell membrane.
Clonal growth of differentiated rabbit cartilage cells
Authors: Ham Richard G. , Sattler Gerald L. 
Published: February 2005

AbstractSingle cell suspensions have been prepared from rabbit cartilage by collagenase digestion in the presence of fetal bovine serum. When inoculated into medium F12 supplemented with 5% fetal bovine serum and 5% rabbit serum, the cartilage cell suspensions yield large healthy colonies of epithelial‐like cells with an average plating efficiency of 47%. At the end of a 14 day incubation period, the centers of many of the colonies are thickened into multilayered aggregates. Such colonies exhibit serveral cartilage‐like properties, including metachromatic staining with toluidine blue, dense brown staining with bismark brown, bright green staining with alcian green, and a refractile matrix which can be seen with the phase contrast microscope to surround the living cells. Similar properties have also been observed in second and third passage subcultures.
Development of 3T3‐like lines from Balb/c mouse embryo cultures: Transformation susceptibility to SV40
Authors: Aaronson Stuart A. , Todaro George J. 
Published: February 2005

AbstractBalb/c mouse embryo cultures that are carried under a rigid transfer schedule that minimizes cell‐cell contact evolve into permanent lines that possess properties very similar to 3T3. From the same embryo cultures, a transfer schedule where cell‐cell contact is extensive leads to lines (Balb/3T12) that form multiple cell layers and have saturation densities up to 25‐fold higher than the Balb/3T3 lines. All the lines are hypotetraploid.Comparison of the Balb/3T3 lines with 3T3 reveals similar morphology, ability to grow at high dilution, low saturation density, and high susceptibility to transformation by SV40 virus. The Balb/3T12 lines, which are continually maintained at high cell density, show little improvement in cloning efficiency. Infection with SV40 produces transformants that can be selected by their ability to form colonies at low cell densities. Using the appropriate selective system for each line, it appears that SV40 T antigen induction and transformation in Balb/3T3 and Balb/3T12 are comparable.
Coupling of excitation and cessation of cyclosis in Nitella: Role of divalent cations
Authors: Barry William H. 
Published: February 2005

AbstractThe effect of external divalent cation salt solutions upon the association of an action potential and cessation of cytoplasmic streaming in Nitella was studied. Nitella cells remained excitable when immersed in solutions of CaCl2, MgCl2, BaCl2, and SrCl2. Cessation of streaming coincident with excitation occurred in solutions of CaCl2 or SrCl2 but not in solutions of MgCl2 or BaCl2. In cells exposed to solutions containing mixtures of MgCl2 and CaCl2, or MgCl2 and SrCl2, it was the [Ca]/[Mg] or [Sr]/[Mg] which determined the effect of an action potential upon the rate of streaming, rather than the absolute concentrations Ca++ or Sr++. The implications of these data are discussed with respect to the structure involved in the generation of cytoplasmic streaming and the relation of streaming to other types of biological motion.
Triggering of the cell cycle in an organized tissue In vitro
Authors: Harding C. V. , Wilson W. L. , Wilson J. R. , Reddan J. R. , Reddy V. N. 
Published: February 2005

AbstractThe rabbit lens can be maintained in culture under conditions which retain the block to proliferation characteristic of many of the cells in the normal tissue in vivo. Proliferation and cell migration subsequently can be triggered at will by the addition of serum to the medium. Serum is not required throughout the whole period of culture in order to elicit this response but only during an initial period which ends prior to the onset of both DNA synthesis and mitosis. The duration of this period of serum‐dependency is specifically related to the location (and hence the state of organization) of the cells within the epithelial layer. Some of the characteristics of the serum factors which promote these reactions and the conditions of culture which affect their activity are reported.
Changes in DNA polymerase activity associated with cell fusion in cultures of embryonic muscle
Authors: O'Neill M. , Strohman R. C. 
Published: February 2005

AbstractIn cultures of differentiating chicken embryo muscle cells there is a steep decline in DNA polymerase activity which closely parallels the time of rapid cell fusion and the formation of multinucleated myotubes. The DNA polymerase activity remaining in the cultures is almost completely associated with single unfused cells. Cell fusion does not require a confluent culture and fusion capability appears to be severely reduced in the remaining single cells following an approximately ten hour time period during which the majority of fusion takes place. A model is presented to explain the observed kinetics of cell growth and cell fusion in vitro.
The rate of attachment of amoebae to the substratum: A study of nuclear‐cytopolasmic relationships
Authors: Lorch I. J. 
Published: February 2005

AbstractThe rate of attachment to the substratum was found to be a strain specific character of certain large free‐living amoebae. Two strains, which differed significantly in this respect, were compared with regard to the rate of attachment of enucleated cytoplasm, nuclear‐cytoplasmic hybrids and amoebae injected with cytoplasm from another strain. It was found that both the nucleus and the cytoplasm of the more rapidly attaching strain were able to transmit this character to amoebae of the more slowly attaching strain. The possible mechanisms underlying attachment and transmission of the rate of attachment are discussed.
Relationship between uridine kinase activity and rate of incorporation of uridine into acid‐soluble pool and into RNA during growth cycle of rat hepatoma cells
Authors: Plagemann Peter G. W. , Ward Gary A. , Mahy Brian W. J. , Korbecki Michal 
Published: February 2005

AbstractUridine kinase activity measured in cell‐free extracts of Novikoff rat hepatoma cells grown in suspension culture fluctuates about 10 fold during the growth cycle of the cells. Maximum specific activity (units/106 cells) is observed early in the exponential phase and then decreases progressively until the stationary phase. The rate of incorporation of uridine into the acid‐soluble pool by intact cells fluctuates in a similar manner and both the rate of uridine incorporation by intact cells and the uridine kinase actvity of the cells increase several fold before cell division commences following dilution of stationary phase cultures with freshmedium. Regardless of the stage of growth, uridine is rapidly phosphorylated to the triphosphate level by the cells.The rates of incorporation of uridine into the nucleotide pool and into RNA by intact cells fluctuate in a similar manner during the growth cycle. However, evidence is presented that indicates that alterations in the rate of incorporation of uridine into RNA are not simply due to changes in the rate of phosphorylation of uridine, but are regulated independently.Inhibition of protein synthesis by treating cells with puromycin or actidione causes a marked inhibition of incorporation of uridine into RNA, but has little effect on the phosphorylation of uridine to UTP for several hours. Thus the depression of incorporation of uridine into RNA probably reflects a decrease in the rate of RNA synthesis as a result of inhibition of protein synthesis. Inhibition of RNA synthesis by treating cells with actinomycin D does not affect the rate of conversion of uridine to UTP and thus results in the accumulation of labeled UTP in treated cells.
Phenotypically variant adrenal tumor cell cultures with biochemical lesions in the ACTH‐stimulated steroidogenic pathway
Authors: Schimmer Bernard P. 
Published: February 2005

AbstractFour clonal adrenal tumor cell lines which exhibit biochemical lesions in the ACTH‐stimulated steroidogenic pathway have been isolated. Two of these cell lines, designated Y‐6 and OS3, appear to contain their lesions at points proximal to cyclic AMP formation in the ACTH‐stimulated steroidogenic pathway. Growth of Y‐6 and OS3 as tumors in isogenic mice results in a restoration of ACTH sensitivity in both cell lines by mechanisms which do not appear to involve selection or fulfillment of specific nutritional requirements. Growth of Y‐6 and OS3 as tumors in heterogenic mice results in restoration of ACTH sensitivity in Y‐6 but not in OS3, suggesting that the biochemical lesions in these cell lines are at different loci. Two other cell lines, designated OS1 and OS4, possess biochemical lesions in the steroidogenic pathway beyond the formation of cyclic AMP and before the formation of pregnenolone. Growth of OS1 and OS4 as tumors in isogenic mice results in the repair of the biochemical lesions in these cells distal to cyclic AMP formation in the ACTH‐stimulated steroidogenic pathway. The four cell lines described are potentially useful in elucidating the mechanism of action of ACTH in adrenal cells as well as in determining the factors required for maintaining differentiated function in cultured cells.
The influence of conditioned media and nonessential amino acid supplementation on the growth of cells in vitro
Authors: Oellermann Rolf A. , Miller Elsa M. 
Published: February 2005

AbstractThe growth enhancing effect of media conditioned by cells from established lines (BHK and L60) is comparable to that of media conditioned by cells of primary origin (chick embryo). However, the properties of the conditioned media from these two systems show marked differences: the growth enhancing factors in the former are dialyzable and heat‐stable, in contrast to the non‐dialyzable and heat‐labile factors in the latter.Media conditioned for only four hours by BHK or L60 cells stimulated cell growth. Amino acid analyses revealed that non‐essential amino acids had appeared in these conditioned media.To verify this as the metabolic basis of conditioning by cells from established lines, media containing dialyzed serum were supplemented with each of six non‐essential amino acids, and assayed on BHK and L60 at various population densities. Serine was the most stimulatory and alanine the most inhibitory of the amino acids tested.Mixed supplementation of the medium showed that when low levels of alanine and serine were added simultaneously, cell growth was enhanced but any increase in the level of alanine required an increase in the level of serine also to achieve growth stimulation.
DNA‐mediated transformation of mammalian cells in culture. Increased transforming efficiency following sonication
Authors: Roosa Robert A. , Bailey Ellen 
Published: February 2005

AbstractA series of 100 experiments was completed to determine if DNA is capable of transforming the genotype of a murine lymphoma (P388) in cell culture. The test system was concerned with the transformation of cells from 8‐azaguanine (AZG) sensitivity to resistance. By the use of this marker, it was determined that transformation by DNA did occur, and that the efficiency of transformation was greatly increased by sonication of the DNA. A statistical analysis of 100 experiments demonstrated that the increase in the number of resistant cells after treatment with sonicated resistant DNA (R‐DNA) was statistically significant (χ2 > 4.25, 0.05 > p > 0.02) in 66% of the experiments. DNA from sensitive parental cells and DNA from other sources produced no effect while DNase and UV treatment abrogated effective transformation by either sonicated or nonsonicated R‐DNA. RNase was without effect.Sucrose gradient analysis of sonicated and nonsonicated R‐DNA demonstrated that the peaks which correspond to the highest specific transforming activity are not altered by sonication and do not coincide with the OD260 peaks, in spite of the fact that sonication shifted the peak of maximum OD260 to a slower sedimenting region of the gradient. The major portion, however, of the transforming material did shift after sonication to the slower sedimenting region of the gradient and did coincide with the OD260 peak.The hereditary stability of the transformed cells was established by cloning a representative number of transformants, growing them in the absence of AZG for an extended period and then testing their ability to grow in graded concentrations of AZG. In addition, DNA extracted from transformants successfully transformed sensitive cells.
Interaction of calcium and local anesthetics with skeletal muscle microsomes
Authors: Bondani Augusto , Karler Ralph 
Published: February 2005

AbstractThe influence of Ca++, several drugs, and pH on the binding of Ca++ by skeletal muscle microsomes was studied in vitro. A mass‐law graphic analysis revealed the presence of three distinct species of Ca++‐binding sites in the microsomes, and the binding at only one of these sites was antagonized by local anesthetics and quinidine. These drugs also decreased the maximum Ca++‐binding capacity of the microsomes. Caffeine and ouabain exerted no effect on the binding at any of the sites. Procaine was also bound by microsomes, and this binding was antagonized by Ca++, which also decreased the maximum procaine‐binding capacity of microsomes. The sites that bind procaine and Ca++ are not identical because the maximum‐binding capacities of the interacting sites are distinctly different. The influence of pH on the ability of drugs to antagonize Ca++ binding indicates that the displacing activity increases as the percentage of the drug in the nonionized form increases. All of the data obtained in the above studies are consistent with the interpretation that quinidine and local anesthetics of the procaine type noncompetitively antagonize the binding of Ca++ by microsomes. The pharmacological significance of a noncompetitive interaction may be related to the property of local anesthetics and quinidine to increase contractile tension in skeletal muscle rather than to their ability to stabilize the cell membrane.
The diversity of sulfhydryl groups in the human erythrocyte membrane
Authors: Shapiro Bernard , Kollmann George , Martin David 
Published: February 2005

AbstractHuman bank blood erythrocytes were exposed to the mercurials p‐chloromercuribenzoate (PCMB), chlormerodrin (CM), p‐chloromercuribenzenesulfonate (PCMBS), and 1‐bromomercuri‐2‐hydroxypropane (BMHP) for different time intervals, at different concentrations and in combination with n‐ethylmaleimide (NEM) added before, and 2‐mercaptoethylguanidine (MEG) and reduced glutathione (GSH) added after the mercurial. Binding patterns of the mercurials to the cells and effects on permeability of the cells were measured. The results indicate that the erythrocyte membrane contains multiple classes of sulfhydryl groups, alteration of which has a variety of effects on cell permeability. PCMB, chlormerodrin and PCMBS react with at least three classes of sulfhydryls, two of which are associated with the sodium‐potassium barrier and, when altered, result in potassium loss, sodium accumulation and hemolysis. BMHP reacts with at least two classes of sulfhydryls, one of which is associated with permeability, and, when altered, results in hemolysis in isotonic solutions of choline chloride or lactose. The results provide additional insight into the structure and function of the erythrocyte membrane.
Histidase function in human epidermal cells
Authors: Barnhisel Mary L. , Priest Robert E. , Priest Jean H. 
Published: February 2005

AbstractThe activity of histidase was studied in (1) epidermal tissue scraped from human infant foreskin, (2) fibroblast‐like cells in monolayer serial culture from human foreskin, and (3) epithelial‐like (epidermal) outgrowth from foreskin primary explants. Foreskin epidermal tissue without in vitro culture and epidermal outgrowth in primary culture from explants of foreskin showed equivalent mean levels of histidase activity, 5.22 × 10−3 and 5.01 × 10−3 μMoles urocanic acid produced per milligram protein per minute. Under the same assay conditions, there was no measurable histidase activity in cultured fibroblast‐like cells from foreskin at various times after subculture. The Km for enzyme from human foreskin epidermal tissue ranged between 2 and 5 × 10−3 M histidine. Ability to demonstrate the presence or absence of this tissue‐specific enzyme function in cultured cells suggests a useful means for studying differentiation, as well as a more precise way to identify epidermal origin of cultured cell types than morphological characteristics alone would permit.
Hemopoietic stem cell distribution in tissues of fetal and newborn mice
Authors: Niewisch Helgard , Hajdik Irene , Sultanian Ishkhan , Vogel Helmut , Matioli Gastone 
Published: February 2005

AbstractThe variations in the distribution of hemopoietic stem cells in fetal tissues are concomitant with changes in the electrophoretic pattern of hemoglobin. The data presented here are consistent with the hypothesis that the embryonic stem cells can be transformed into adult stem cells in the liver of 15 to 16 days old fetuses.
Mammalian cell fusion III. A hela cell inducer of premature chromosome condensation active in cells from a variety of animal species
Authors: Johnson R. T. , Rao P. N. , Hughes H. D. 
Published: February 2005

AbstractThe phenomenon of premature chromosome condensation (PCC) is induced in unstimulated horse lymphocytes, bovine spermatozoa, Chinese hamster ovary cells, embryonic chick fibroblasts and erythrocytes, Xenopus kidney and mosquito cells by fusing each of these cell types with HeLa cells blocked in mitosis. Thus it becomes possible to visualize chromosomes even from non‐multiplying cells of heterologous species, such as, chick erythrocytes and bovine spermatozoa.
The effect of drugs on the rate of proteolysis in Vitro within secondary liver lysosomes
Authors: Bertini Francisco , Bari Daniel R. 
Published: February 2005

AbstractThe in vitro hydrolysis rate of intravenously injected 131 I‐albumin inside mouse liver phagolysosomes was studied for this type of secondary lysosome, when incubated at pH 5.0 and 37°C in the presence of different drugs. While vitamin A alcohol and etiocholanone showed inhibitory effects, suitable concentrations of chloroquine activated that intraparticulate hydrolysis. On the contrary cortisone, in various concentrations, did not alter the hydrolysis rate of the labeled albumin. Neither cortisone nor chloroquine modified the inhibitory effect of vitamin A. The hypothesis that the drugs act on the hydrolysis rate because they modify the stability of this type of secondary lysosome is forwarded.
The relationship of DNA synthesis to protein accumulation in the cell nucleus
Authors: Auer G. , Zetterberg A. , Foley G. E. 
Published: February 2005

AbstractThe relationship between DNA synthesis and protein accumulation in cell nucleus and cytoplasm has been investigated by the use of a combination of ultramicrointerferometric and ultramicrospectrophotometric methods.5‐Fluoro‐2'‐deoxyuridine (FUdR) inhibited DNA synthesis, resulting in inhibition of cell proliferation in G‐1 and early S‐phase. However, synthesis and accumulation of protein continued in the presence of FUdR, as indicated by a 54% increase in the average dry mass value per individual cell during 18‐hour exposure to FUdR; due primarily to protein accumulation in the cytoplasm, the average cytoplasmic dry mass increased by as much as 85%, while the dry mass of the nucleus increased by only 21%.The dry mass values of individual nuclei were well‐correlated to the nuclear DNA content throughout the period of exposure to FUdR. In contrast to the continued accumulation of protein in the cytoplasm during inhibition of DNA synthesis, protein accumulation in the nucleus was inhibited. When cells were released from inhibition of DNA synthesis by the addition of 2'‐deoxythymidine, the nuclear DNA content and nuclear dry mass increased in near‐synchrony, there being some evidence that DNA synthesis was initiated somewhat prior to initiation of increase in nuclear dry mass.Thus, it appears that DNA synthesis (or an increase in nuclear DNA content) is intimately related to the regulation of protein accumulation in the nucleus.
Transformation of granulocytes to macrophages in bone marrow colonies in vitro
Authors: Metcalf Donald 
Published: February 2005

AbstractSingle cells from developing two day granulocytic bone marrow colonies were transfered in agar cultures. After three to five days, 48 of 239 transfered single cells had transformed to single macrophages or proliferated to form aggregates of pure macrophages or mixed macrophage‐granulocyte aggregates. Some granulocytes in colonies developing in vitro from bone marrow cells appear to have the capacity to transform to macrophages.
Stimulation by serum of multiplication of stationary chicken cells
Authors: Temin Howard M. 
Published: February 2005

AbstractWhen serum was added to cultures of stationary chicken fibroblasts, there was an increase in the percentage of cells synthesizing DNA after a delay of about five hours. If the serum was removed before DNA synthesis began, some cells were still found to start DNA synthesis and to enter mitosis. The delay between the time of addition of serum and the start of DNA synthesis was not affected by the type of serum, the concentration of serum, nor the means of preparing the stationary cells. However, all of these factors affected the proportion of cells stimulated by serum.If two pulses of serum were given immediately following each other, their effects were synergistic. If there were twelve hours between them, there was no effect of the first pulse. These results were summarized in a new model of the cell cycle which subdivided the G1 phase into Gla, b, and c.The effects of serum were seen in a balanced salt solution, and were sensitive to several metabolic inhibitors.