bluuebunny/crossref_metadata_2025_split huggingface dataset:
The action of mendelian genes in human diploid cell strains
Authors: Krooth Robert S. , Sell Elizabeth K. 
Published: February 2005

AbstractSome of the cells of every human being will grow outside the body as microorganisms. It is possible to show, in a variety of ways, that these cells resemble genetically the individual from whom they were obtained. Over 35 inherited human diseases and anomalies can now be studied in such cell lines.Human diploid cell strains, biochemically marked by one or more mutant Mendelian genes, have proven particularly useful for the study of gene action in man and for the detection of genetic changes such as mutation and somatic cell hybridization. In addition, the strains have a number of clinical applications, including the antenatal diagnosis of inherited disease.The failure of cultured human cells to display their phenotype at most loci continues to restrict their use in both genetics and medicine. There are reasons for hoping that this difficulty will eventually be solved, and some experiments bearing on the problem are already feasible.
An introspective view of penicillinase
Authors: Saz Arthur K. 
Published: February 2005

AbstractBased both on a review of the literature dealing with penicillinase induction as well as published data from this laboratory, the thesis is presented that penicillinase serves an important metabolic function in producing cells, far more significant than the ability to hydrolyze certain penicillins. An attempt is made to implicate the enzyme in the sporulation process in sporeforming cells and in cell wall metabolism in non‐spore‐forming organisms.
Changes in the carbohydrate content of the KB cell during the growth cycle
Authors: Glick Mary Catherine , Gerner Edward W. , Warren Leonard 
Published: February 2005

AbstractKB cells were grown in suspension culture and synchronized with a double thymidine block. Cells were removed at various times during the cell cycle and analyzed for sialic acid, fucose, mannose and galactose. The mannose, galactose, and fucose contents of the cells all showed a decrease during the mitotic phase. The content of sialic acid decreased, but later in the cycle. When the cell was not dividing the molar rations of sialic acid to fucose: mannose: galactose were approximately 2:5:3 when sialic acid was expressed as 1; the ratios dropped to approximately 1:3:1.5 throughout division. These results indicate that the glycoprotein and/or glycolipid contents of KB cells probably change throughout the cell cycle.
Metabolic effets of nucleosides in rat thymus cells in vitro
Authors: Thomson Marnie J. , Garland Maureen R. , Richards James F. 
Published: February 2005

AbstractThe incorporation of pyrimidine nucleosides into deoxyribonucleotides by rat thymocytes in vitro was decreased by the addition of any one of several nucleosides. In cells incubated with deoxyguanosine, the decrease was apparently caused by interference with the ribonucleotide reductase reaction, and at least part of the effect of deoxyadenosine was produced in the same way. While ara‐C also produced a decrease in labelling of deoxynucleotides, this was quantitatively less than the effect on DNA synthesis, and may have resulted from an indirect effect on the reductase by a deoxyribonucleoside triphosphate which accumulated due to a direct effect of an ara‐C derivative on the DNA polymerase. Cells incubated in the presence of adenosine showed a decreased labelling of deoxynucleotides and DNA due to inhibition of earlier steps in utilization of the labelled precursor, its uptake and phosphorylation. Guanosine, or a derivative, apparently reduced labelling of DNA and RNA even at concentrations which produced no alteration in uptake and phosphorylation of the precursor. An effect on the reductase was indicated.Uptake and phosphorylation of the pyrimidine ribonucleosides seem to be separate processes, since each can vary independently of the other when cells are incubated in the presence of various concentrations of exogenous nucleosides.
Factors affecting the production of glutamine in cultured mouse cells
Authors: Barnes Paul R. , Youngberg Dean , Kitos Paul A. 
Published: February 2005

AbstractGlutamine synthetase activity of NCTC clone 929 mouse cells (strain L) was studied as a function of the prior nutritional experience of the cells. Small enzyme increases were recorded in response to either glutamine depletion or chronic serum supplementation of the growth medium. Somewhat greater increases resulted from the administration of cortisol or certain other steroids, particularly if the hormone treatment was combined with glutamine withdrawal. High concentrations of glutamate in the medium did not augment the glutamine synthetase content of the cells and even caused an apparent decrease in it. The presence of glutamine in the culture medium resulted in a fairly rapid rate of disappearance of the glutamine synthetase of previously induced cells. The data suggest that glutamine and cortisol act independently on the cells in regulating the level of the enzyme.
Differential actions of insulin on enzyme activities in mammary organ culture
Authors: Rivera E. M. , Cummins E. P. 
Published: February 2005

AbstractMammary explants from midpregnant mice were cultured for 4, 24, 48, and 72 hours in the presence and absence of insulin. Changes in the activities of phosphoglucose isomerase (an enzyme of the glycolytic pathway for glucose metabolism) and of glucose‐6‐phosphate and 6‐phosphogluconate dehydrogenases (enzymes of the pentose phosphate pathway) were assessed at each culture interval. During the first four hours of culture, no significant effect could be attributed to insulin on the activity of these enzymes. Moreover, insulin had no detectable stimulatory effect on phophoglucose isomerase until 48 hours, at which time the hormone caused a marked increase in the activity of this enzyme over the next 24 hours. In contrast, insulin stimulated only a small increase in dehydrogenase activity at 24 hours, after which this hormone acted mainly to maintain the activity that was present initially. These results indicate differential actions of insulin on two groups of enzymes catalyzing the same substrate.
Cell surface negativity and the binding of positively charged particles
Authors: Weiss L. , Zeigel R. 
Published: February 2005

AbstractThe binding of positively charged, colloidal ferric oxide particles to the surfaces of Ehrlich ascites tumour cells, before and after incubation with neuraminidase and/or ribonuclease, has been studied by electron microscopy. An attempt has been made to correlate the amount of binding observed, with the electrophoretic mobilities of the cells under similar conditions to those under which they were exposed to the ferric oxide.Although a progressive loss of staining was observed with progressive loss of cellular net surface negativity, neither property was predictable from knowledge of the other. Some of the difficulties inherent in quantitative staining techniques of this type are discussed.
The effects of lactose on human erythrocytes
Authors: Kollmann George , Shapiro Bernard , Martin David 
Published: February 2005

AbstractHuman erythrocytes suspended in isotonic lactose solution lost potassium and continued to lose potassium even when resuspended in isotonic sodium chloride. The same phenomenon was observed when the cells were suspended in an isotonic solution of the sodium salt of glutamate, a nonpenetrating anion. The presence of 5 mEq per liter of sodium chloride in the lactose or sodium glutamate suspensions greatly reduced the initial potassium loss and the potassium loss when the cells were resuspended in sodium chloride solution. Salts of nonpenetrating anions were less or not effective in blocking lactose damage. The results indicate that absence of penetrating anions in the suspending media is the initiating condition of lactose damage. Chloride and consequently potassium are lost from the erythrocyte. Changes in cellular ionic pattern and/or changes in the cell membrane result in a nontransient damage manifested by continued potassium loss by lactose‐treated cells resuspended in isotonic NaCl.
Responses of neuroblastoma cells to iontophoretically applied acetylcholine
Authors: Nelson P. G. , Peacock J. H. , Amano T. 
Published: February 2005

AbstractDissociated mouse neuroblastoma cells were studied in vitro by using intracellular microelectrodes for electrical stimulation and recording. Some, but not all cells, which exhibited well developed action potentials to electrical stimulation also showed changes in membrane potential to iontophoretically applied acetylcholine (ACh). The types of responses to ACh varied. Short latency depolarizing responses to pulses of ACh (similar to those obtained with skeletal muscle) as well as sustained depolarization to steady ACh application (D response) occurred. A longer latency prolonged hyperpolarizing response (H response) and bi‐ and triphasic combinations of H and D responses were also seen.Pairs of cells showing morphologic contact were tested for the occurrence of effective synaptic coupling by placing intracellular microelectrodes in each cell. In none of 95 cases tested did spike activity produced by direct electrical stimulation of one cell elicit a synaptic potential of 200 μv or more in the other.
Hematopoietic stem cells from mice with erythroblastosis
Authors: Hajdik I. , Niewisch H. , Matioli G. 
Published: February 2005

AbstractThe infection of newborn mice with a mouse erythroblastotic virus increases the number of hematopoietic stem cells in the spleen. Upon retransplantation of these stem cells into intermediate recipient mice certain growth parameters (doubling time, self renewal and extinction probability, etc.) which are abnormal when measured by techniques which avoid the intermediate recipient step, appear to be reverted toward normal values. The “normalization” of the stem cells is explained by the change in the environment supporting CFU growth during transplantation.
Distinctions between rabbit lymph node cell populations responding to primary and secondary injections of keyhole limpet hemocyanin
Authors: Folds J. D. , Roszman T. L. , Stavitsky A. B. 
Published: February 2005

AbstractRabbits were injected once or twice into the hind foot pads with alum‐precipitated keyhole limpet hemocyanin. At the height of the primary or secondary responses individual rabbits were sacrificed for the preparation of lymph node cell suspensions from the regional lymph nodes. These cells were employed for the in vitro study of antibody synthesis by the incorporation of 14C‐leucine and the secretion of antibody by the time of appearance of radioactive antibody in the medium. The primary response cells rapidly synthesized and secreted IgM and IgG antibodies. The secondary response cells rapidly synthesized IgM and IgG antibodies, secreted IgG antibody promptly, but secreted the IgM antibody with a lag of six to ten hours. Microsomal fractions could not be prepared from the primary response cells, but were readily produced from the cells of the secondary response. The primary response cells contained mainly free ribosomes, those of the secondary response predominantly membrane‐bound ribosomes. It was postulated that IgM antibody was not secreted until it was glyco‐sylated in the Golgi apparatus and that the lag in secretion entailed the time for this rate‐limiting step to occur.
Susceptibility of primate‐mouse hybrid cells to SV40
Authors: Knowles Barbara B. , Barbanti‐Brodano Giuseppe , Koprowski Hilary 
Published: February 2005

AbstractPrimate‐mouse hybrid cells were challenged with SV40 DNA and monitored for their ability to produce virus. All of the hybrid cells had lost at least half of their primate chromosomes at the time of challenge. Only SV40 T‐antigen‐positive hybrid cells derived from an SV40‐transformed human parental cell produced SV40. This finding suggests that the chromosome(s) necessary for SV40 replication are easily lost on fusion of mouse and primate cells unless the parental cells are already SV40‐transformed.
Diffusion chamber and spleen colony assay of murine haematopoietic stem cells
Authors: Breivik Harald , Benestad Haakon Breien , Bøyum Arne 
Published: February 2005

AbstractMouse bone marrow cells have been cultured in diffusion chambers and their capacity to form spleen colonies in irradiated mice investigated after different culture periods. The number of spleen colony‐forming units (CFU) in the chambers decreased during the first day of culture. The number then increased rapidly to a level significantly above the original chamber value on the third to fifth day of culture. By that time large numbers of granulocytes and macrophages had also appeared.Histological examination of spleen colonies showed that prior culturing did not alter the ratio between the different types of colonies.Cultured bone marrow cells which were transferred to new chambers retained granulopoietic capacity. This capacity increased between the first and second day of primary culturing. At this time hydroxyurea injections to chamber hosts revealed that the progenitor cells were proliferating.The results show that the granulopoietic progenitor cells of the chambers are stem cells, and that one progenitor cell type is identical with the CFU.
Haematopoietic stem cell content of murine bone marrow, spleen, and blood. Limiting dilution analysis of diffusion chamber cultures
Authors: Breivik Harald 
Published: February 2005

AbstractSuspensions of mouse bone marrow cells, spleen cells, and blood leucocytes were cultured in diffusion chambers in dilution series in order to establish the minimum concentrations of haematopoietic stem cells (HSC). The observed frequencies of empty chambers after seven days of culture conformed to the expected frequencies of a null response in a Poisson distribution. The proportions of empty chambers could therefore be used to estimate the concentrations of HSC in the cell suspensions. The following numbers of HSC per 105 cells were found (with 95% confidence limits): Bone marrow: 50 (44–56). Spleen: 3.5 (2.8–4.3). Blood leucocytes: 1.4 (1.2–1.8). The mean (± standard error) HSC‐content per femur, spleen, and milliliter blood when pooling cells from three to six donor mice was 8240 ± 600, 7660 ± 490, and 56 ± 6.5 respectively.For comparison, the HSC concentrations were also determined with the spleen colony technique; the ratio between the HSC‐concentrations of bone marrow, spleen, and blood determined with the diffusion chamber technique was similar to that determined with the spleen colony technique.
Genetics of somatic mammalian cells XII: Mutagenesis by carcinogenic nitroso compounds
Authors: Kao Fa‐Ten , Puck Theodore T. 
Published: February 2005

AbstractFour known carcinogenic compounds, all of which contain the nitroso group, have been found to be effective in producing cell killing, chromatid breaks, mutagenesis and chromatid rearrangements in Chinese hamster ovary cells. Single cell survival curves revealed these agents to exhibit a 50,000‐fold difference in their mean lethal dose (Do) values. However, all agents yielded constant values for their efficiencies of production of chromatid breaks and single gene mutagenesis, but not chromatid rearrangements, when these were expressed in terms of the Do value of each agent. Three of the carcinogens produced single‐hit and one produced a multiple‐hit survival curve. The system offers distinct advantages in study of the interrelationships between mutagenic and carcinogenic actions in mammalian cells.
Properties of the mouse embryo conditioned medium factor(s) stimulating colony formation by mouse bone marrow cells grown in vitro
Authors: Stanley E. R. , Bradley T. R. , Sumner M. A. 
Published: February 2005

AbstractThe properties of the mouse embryo cell conditioned medium (ECM) colony stimulating factor(s) from six day mouse embryo cultures have been examined. The general properties were similar to those described previously for the human urine colony stimulating factor. The ECM colony stimulating activity (CSA) was not lost following treatment with nucleases, glycosidases, phospholipases and proteolytic enzymes with the exception of α‐chymotrypsin. ECM CSA was lost following mild periodate treatment.Fractionation of ECM CSA revealed a slight size heterogeneity on gel‐filtration and on zone sedimentation in sucrose gradients. There was a discrepancy between the apparent molecular weights determined by gel‐filtration (70,000–150,000) and by zone sedimentation (64,000) as has been reported previously for other colony stimulating factors. A gross charge heterogeneity of ECM CSA was apparent on electrophoresis and DEAE‐cellulose chromatography, and a heterogeneity of the elution profile on stepwise elution from calcium phosphate gel was observed. This heterogeneity was still apparent in the presence of 6M urea and appeared to be unchanged following re‐chromatography on DEAE‐cellulose under the usual fractionation conditions. These studies suggested that the heterogeneity was not due to easily reversible combinations of active subunits.The electrophoretic heterogeneity of six day ECM CSA was found to develop gradually from an electrophoretically monodisperse band at day 2 of culture. Experiments in which preparations containing concentrated monodisperse ECM CSA were added back to culture dishes during and after ECM production suggested that the development of heterogeneity was related to the production or release of factor(s) from the cells rather than the action on the colony stimulating factor(s) of an extracellular enzyme in the medium. Alteration of the electrophoretic mobility of six day ECM CSA by incubation with purified sialidase suggested the presence of sialic acid on the active molecules.Purification procedures for the ECM factor(s) were not developed to any large extent primarily in view of the charge heterogeneity. The results of this study suggest that the ECM colony stimulating factor(s) is a glycoprotein(s).
An inhibitor of protein synthesis in cytoplasmic extracts of density inhibited cells
Authors: Engelhardt Dean L. 
Published: February 2005

AbstractCytoplasmic extracts of green monkey kidney‐Vero M3 cells that have been grown to high cell density and have entered the stationary phase of growth lose the capacity to synthesize proteins after they have been frozen and thawed. The same loss of protein synthetic capacity is not observed when cytoplasmic extracts of low cell density Vero M3 or HeLa S‐3 cells are frozen and thawed before assay, nor when high cell density Vero M3 cell extract is assayed without having been frozen. The loss of the protein synthesis capacity of the frozen and thawed extracts of stationary phase Vero M3 cells is accounted for by the appearance of an inhibitor. The inhibitor is precipitated in the 30 to 70% ammonium sulfate fraction of the 100,000 g supernatant. It is inactivated by heat and is non‐dialyzable. It blocks the transfer of amino acids from tRNA to growing peptide chains.The amount of this inhibitor in the extract (measured by relative inhibition of in vitro protein synthesis) increases as a function of the density of the cells from which the extract was made, and the increase can be correlated with the progressive turnoff of protein synthesis in whole cells.
Susceptibility to polycythemia of hemopoietic spleen colonies produced by cultured embryonal liver cells
Authors: Latsinik Natalia V. , Samoylina Nina L. , Chertkov J. L. 
Published: February 2005

AbstractThe survival of colony‐forming cells in organ cultures of the mouse embryonal liver was studied. During cultivation colony‐forming cells acquire the type of regulation characteristic of the adult organism. Factors affecting the change in the type of regulation from embryonal to adult of the hemopoietic stem cells in cultures are discussed.
The kinetics of resensitization of Tetrahymena following recovery from effects of cycloheximide
Authors: Heyer Carolyn B. , Frankel Joseph 
Published: February 2005

AbstractSynchronized cells of Tetrahymena pyriformis strain GL‐C were exposed to cycloheximide (CHI) (0.2 μg per ml) from 40 to 140 minutes after the end of the heat synchronizing treatment. Recovery takes place during this treatment (Frankel, 1970). The CHI was washed out at 140 minutes. At various times after washout dividing cells were isolated in micro‐drops under oil, and one daughter was transferred to a test drop containing CHI (0.2 μ per ml). The generation time of both daughters was recorded, and the “percent prolongation” of generation time brought about by the test exposure of one cell to CHI was computed for each cell‐pair. This procedure was carried out for groups of cell‐pairs at different times after the end of the CHI pretreatment. Comparable tests were performed with two control series, one which had not previously been exposed to CHI and another for which CHI was present continuously. Comparison of the prolongation observed in control and experimental series demonstrated that cells which have earlier undergone recovery in CHI gradually become resensitized following washout of the drug. Cells progressively lose most of their original resistance in a period of somewhat over three cell generations; however, a small but significant fraction of this resistance is still retained seven to eight generations after the CHI pretreatment.
Coordination of ribosomal RNA synthesis in vertebrate cells
Authors: Hill Richard N. , McConkey Edwin H. 
Published: February 2005

AbstractXenopus embryo cells and HeLa cells were investigated under various conditions to test for coordinate synthesis of high molecular weight (28S and 18S) and low molecular weight (5S) rRNA. Xenopus embryos initiate 28S and 18S rRNA synthesis at gastrulation (Brown and Littna, '64); we found that 5S rRNA synthesis is coordinately initiated with the 28S and 18S rRNAs at the same time in development. Dissociated Xenopus blastula cells were cultured in vitro for several hours to condition the medium; post‐gastrula cells were then grown in the conditioned medium to test for the existence of an inhibitor of rRNA synthesis. No inhibitor was detected.Low doses of actinomycin D profoundly inhibit the synthesis of 28S and 18S rRNA in HeLa cells, while 5S rRNA synthesis is less affected by this treatment. Therefore, actinomycin D does not produce a coordinate inhibition of all rRNA species. Similar effects of the antibiotic were found in cultured amphibian cells. Synchronized HeLa cells reinitiating RNA synthesis following mitosis also respond to actinomycin D in a non‐coordinate manner.
The release of membrane‐bound calcium by radiation and sulfhydryl reagents
Authors: Tolberg Adelaide B. , Macey Robert I. 
Published: February 2005

AbstractEffects of ionizing radiation and of sulfhydryl reagents on the 45Ca binding of red cell membranes were studied. Corresponding effects of these agents on potassium leak from intact red cells were also determined. Essentially all the 45Ca associated with the ghosts appeared to be bound. Calcium binding could be described by assuming two independent groups of binding sites with dissociation constants of about 6 × 10−4 m and 2 × 10−4 m. The total binding capacity was about 2.5 × 10−4 moles/g ghost protein. Membrane calcium was decreased by radiation and by the two sulfhydryl reagents, p‐chloromercuribenzoate (PCMB) and N‐ethyl maleimide (NEM). The tightly bound calcium fraction appeared to be most affected by these agents. Changes in potassium leak evoked by varying doses of agents appeared to parallel effects on membrane calcium. These investigations suggest that the increased cation permeability observed after exposure or red cells to radiation or sulfhydryl reagents may be related to alterations in the calcium‐binding properties of the cell membrane.