bluuebunny/crossref_metadata_2025_split huggingface dataset:
pH dependence of the effect of adenosine triphosphate and ethylenediaminetetraacetate on sodium and magnesium binding by cellular membrane fragments
Authors: Sanui Hisashi 
Published: February 2005

AbstractThe pH dependence of previously reported effects of adenosine triphosphate (ATP) and ethylenediaminetetraacetate (EDTA) on cation binding by rat liver microsomes was studied by an equilibration and washing procedure. Equilibration of microsomes in media containing 95 mM NaCl and 4 mM MgCl2 with pH varied from 4 to 8 resulted in an increase in bound cations from zero below pH 4 to 0.90 mmoles Mg and 0.34 mmoles Na/g N at pH 8; the ratio of bound Na/bound Mg increased from 0.15 at pH 5 to 0.38 at pH 8. Addition of 5 mM EDTA to the equilibration media produced striking changes in cation binding such that bound Na/bound Mg increased from 0.30 at pH 5 to 3.90 at pH 7 and decreased to 3.55 at pH 8. In the presence of added 10 mM ATP, bound Na/bound Mg increased from 0.10 at pH 5 to a maximum of 0.80 at pH 7. The observed changes could generally be correlated with known mass law relationships, although the system containing added ATP was complicated considerably by the hydrolysis of ATP. Results demonstrate that environmental pH is an important factor in determining the effect of ATP and EDTA on the cation binding pattern of cellular membranes. Because hydrogen ion is a product of ATP hydrolysis as well as of other metabolic reactions, the described interactions may be of particular significance in the molecular mechanisms of ATP effects on cation binding and transport in living cells.
Studies on colony formation in vitro by mouse bone marrow cells. II. Action of colony stimulating factor
Authors: Metcalf Donald 
Published: February 2005

AbstractAn analysis was made of some of the processes involved in the stimulation by colony stimulating factor (CSF) of cluster and colony formation by mouse bone marrow cells in agar cultures in vitro. Colony formation was shown to be related to the concentration and not the total amount of CSF. The concentration of CSF determined the rate of new cluster initiation in cultures and the rate of growth of individual clusters. Colony growth depleted the medium of CSF suggesting that colony cells may utilise CSF during proliferation. Bone marrow cells incubated in agar in the absence of CSF rapidly died or lost their capacity to proliferate and form clusters or colonies. CSF appears (a) to be necessary for survival of cluster‐and colony‐forming cells or for survival of their proliferative potential, (b) to shorten the lag period before individual cells commence proliferation and (c) to increase the growth rate of individual clusters and colonies.
Parathyroidectomy and the induction of thymic atrophy in normal, adrenalectomized and orchidectomized rats
Authors: Perris A. D. , Weiss L. A. , Whitfield J. F. 
Published: February 2005

AbstractParathyroidectomy or thyroparathyroidectomy in the male rat results in the severe atrophy of the thymus gland. This effect is not mediated by a secondary release of the cytolytic adrenal or gonadal steroids since it also occurs in adrenalectomized and orchidectomized animals. The loss of the parathyroid gland decreases the flow of thymic lymphocytes into mitosis; this inhibition of cell production leads to the marked decline in thymic weight. The effect can be partially prevented by administration of parathyroid hormone or calcium gluconate.
Further studies on the differentiation of a cell line of myeloid leukemia
Authors: Ichikawa Yasuo 
Published: February 2005

AbstractA limited time of contact with a conditioned medium from embryo cells induced phagocytotic activity in a cell line of myeloid leukemia followed by the loss of colony forming and leukemogenic capacity. After two days in a high concentration of the conditioned medium, the colonies showed morphological changes which indicated the differentiation of this line of cells. The differentiation‐stimulating factor present in the conditioned medium was relatively thermolabile, while the growth‐stimulating factor was highly thermostable. Both factors could pass through a dialysis membrane.
SDS‐acrylamide gel electrophoresis and its application to the proteins of poliovirus‐and adenovirus‐infected human cells
Authors: Maizel Jacob V. , Summers Donald F. , Scharff Matthew D. 
Published: February 2005

AbstractSensitive techniques for acrylamide gel electrophoretic analysis have been applied to animal virus systems and have proven generally useful. Estimates of the number of kinds, molecular weights and number of molecules of proteins in almost any biological sample have been made with ease. As applied to the poliovirus‐HeLa cell system they reveal four major proteins in the virion and at least ten additional proteins in the infected cell. Some of the intracellular and particulate proteins undergo cleavage reactions following a unique translation in which the genome is apparently translated in toto as one large polypeptide of molecular weight greater than 200,000 daltons. The splits occur at three levels: (a) during synthesis; (b) at intermediate stages; and (c) co‐incident with maturation. In vitro studies on protein synthesis, RNA synthesis and virus assembly have substantiated and extended the in vivo observations. The structure of the adenovirion has been established in detail. Hexon, penton base, fiber and core polypeptides and certain relevant subviral structures have been identified. Nearly all of the proteins synthesized in the infected cells after 20 hours are viral. The major structural antigens (hexon and penton) predominate and are made in 10 to 50 fold excess but the internal core polypeptides are not produced in great excess. Studies on the synthesis of polypeptides and their assembly into morphological subunits and virions show that hexon and penton polypeptides are made in about four and two minutes respectively on cytoplasmic polyribosomes, that morphological subunits are formed within five minutes of synthesis of protein, and that there is a delay of greater than one half hour for entry of hexons into virions.
Responsiveness of normal and transformed rat embryo cell cultures to poly I · poly C and interferon
Authors: Freeman Aaron E. , Uhlendorf Carol P. , Younkers Penny E. , Baron Samuel 
Published: February 2005

AbstractA number of normal rat cell cultures as well as cultures transformed spontaneously, by chemicals, and/or by oncogenic viruses were tested for responsiveness to the interferon inducer polyinosinic·polycytidylic acid, or to exogenous interferon. Responsiveness, or lack thereof, had no correlation with subculture passage number, infection with RNA leukemia virus, morphological transformation by oncogenic RNA or DNA viruses, chemical treatment, or the ability of these cells to produce tumors in isologous host animals. The data indicate that lack of response to interferon or to the inducer is neither a necessary prerequisite nor an absolute result of cellular transformation of rat cells.
Cholinergic‐stimulated alkaline phosphatase secretion and phospholipid synthesis in guinea pig seminal vesicles
Authors: Lockwood D. H. , Williams‐Ashman H. G. 
Published: February 2005

AbstractIncubation of slices of seminal vesicles of the guinea pig with cholinergic drugs led to an enhanced secretion of alkaline phosphatase. Incubation with carbamylcholine also stimulated the incorporation of P32 into the phospholipid fraction. Both cholinergic effects required a supply of energy since dinitrophenol was inhibitory. The stimulation of enzyme secretion and phospholipid synthesis by carbamylcholine was completely abolished by atropine. Omission of calcium ions from the incubation medium and pre‐treatment of the slices with ethylenediaminetetraacetic acid (EDTA) caused a marked reduction in alkaline phosphatase secretion induced by carbamylcholine but had no effect on incorporation of P32 into phospholipids. Adenergic agents such as epinephrine, norepinephrine and isoproterenol did not influence these two processes. Addition of cyclic AMP, dibutyryl cyclic AMP and a phosphodiesterase inhibitor was also ineffective. The incorporation of P32 into the various phospholipids of the seminal vesicle was examined. In the presence of carbamylcholine, there was a marked increase in the P32‐specific activities of phosphatidylinositol (nearly 6‐fold) and of phosphatidylserine (about 1.5‐fold). These observations indicate that the guinea pig seminal vesicle, a large hollow organ composed of a single layer of epithelium, is ideally suited for studies concerning the biochemistry of macromolecular secretion.
Shifts in nuclear and cytoplasmic nucleic acid content in temperature‐synchronized Tetrahymena pyriformis (HSM)
Authors: Lane Nancy M. , Padilla George M. 
Published: February 2005

AbstractNuclei were isolated by exposing temperature synchronized Tetrahymena pyriformis (HSM) to Triton‐X‐100. Cell division synchrony was induced with a repetitive 12‐hour temperature cycle (9.5 hours at 13°, 2.5 hours at 29°). Increase in nucleic acid content was biphasic: primarily during the last two hours of the cold period well in advance of the synchronous burst of division and secondarily in the last hour of the warm period. Nuclear RNA content rises almost two hours ahead of cytoplasmic RNA which shows a maximum 0.5 hour before the onset of the warm period. The DNA content reaches a peak 30 minutes later. On the basis of these shifts there appears to be not net synthesis of nucleic acids during cell division. The changes in RNA/DNA of the isolated macronuclei and micronuclei suggest enhanced RNA turnover, loss to the cytoplasm and enhanced ribonuclease activity prior to cell division. Cytoplasmic RNA also appears to be subject to enzymic degradation.
Uridine transport and RNA synthesis in growing and in density‐inhibited animal cells
Authors: Weber Michael J. , Rubin Harry 
Published: February 2005

AbstractBoth chick embryo fibroblasts and mouse 3T3 cells reduce the rate at which they incorporate H3 uridine into RNA as their growth becomes inhibited at high cell density. This reduction occurs as a function of the cell population density, and with chick embryo cells (in contrast to 3T3 cells) it is not accompanied by significant medium alterations. This indicates the importance of the cell population density in the control of cellular metabolism.The decline in H3 uridine incorporation is paralleled by a decline in the rate of uptake of the isotope into the acid‐soluble pool, suggesting that decreased entry of H3 uridine into the cell, rather than a decreased rate of RNA synthesis, is responsible for the reduced rate of incorporation into RNA of density‐inhibited cells. This suggestion was confirmed by finding that when the restriction on uridine uptake was overcome by increasing the concentration of uridine in the medium, the density‐dependent inhibition of uridine incorporation was largely reversed. We conclude that, even though the rate of H3 uridine incorporation into RNA is reduced three‐ to five‐fold in density‐inhibited cells, the rate of synthesis of pulse‐labeled RNA continues at 70 to 85% of the rapidly‐growing rate.
Stabilizing effects of D2O on the microtubular components and needle‐like form of heliozoan axopods: A pressure‐temperature analysis
Authors: Marsland Douglas , Tilney Lewis G. , Hirshfield Michael 
Published: February 2005

AbstractA systematic study of the resistance of heliozoan axopodia to pressure‐induced disintegrational changes has shown that progressively higher concentrations of D2O in the environing medium produce a progressively greater stability, not only as to the needle‐like form of the whole axopodia, but also as to their microtubular components. Also it was found that a higher temperature (25°C) yielded significantly higher stability values with identical degrees of deuteration, as compared with experiments performed at a lower temperature (20°C).
An improved heat‐stable glutamine‐free chemically defined medium for growth of mammalian cells
Authors: Nagle Stanley C. , Brown Bruce L. 
Published: February 2005

AbstractA heat‐stable chemically defined medium, free of glutamine, is described for the growth of mammalian cells in suspension culture. The presence of L‐alanine in the defined medium permitted the omission of glutamine. A 22‐fold increase in the population of a substrain of mouse L cells was obtained (3.4 × 106 cells/ml) in six days with no medium replenishment during incubation. Maximum yields (27 × 106 cells/ml) were obtained by daily medium replacement and venting of cultures. Growth was also improved in a line of cat kidney cells and HeLa cells, and in another substrain of L cells.
Electrophoretic studies of muscle proteins. II. Complex formation between delta protein, myogen and myosin
Authors: Amberson William R. , Bauer Adelia C. 
Published: February 2005

AbstractIn actin‐free extracts of rabbit white muscles complexes form between delta protein, myogen (mainly glycolytic enzymes) and myosin, detectable in electrophoretic patterns of both limbs. The complexes are concentration sensitive, nearly absent when total protein is below 5 mgm/ml, but increasing at higher concentrations. At 65 mgm/ml about 60% is bound at 1°C.Complex concentrations can be calculated by making Rayleigh fringe counts on two portions of the same solution, one more concentrated, the other diluted with buffer. A “fringe balance” can then be constructed which measures the forward movement, in the concentrated descending pattern, of those portions of myogen and myosin which have united with delta and moved with it in a fast position. Similar calculations are possible for the ascending limb.When commercial aldolase or lactic dehydrogenase solutions are mixed with concentrated extracts from which most free myogen has been removed the patterns show that portions of the added enzymes have complexed with myosin and delta and move with them in fast positions.Mixtures of pure aldolase and nearly pure myosin solutions also show com‐plexing, less well developed than when other enzymes are present. The glycolytic enzymes may have to unite with each other before they can readily complex with myosin and delta. There may be a lineal order of the glycolytic enzymes laid out along the fibrous proteins, permitting a rapid handling of their substrates.
Electrogenesis in mouse neuroblastoma cells In vitro
Authors: Nelson P. G. , Peacock J. H. , Amano T. , Minna J. 
Published: February 2005

AbstractIntracellular microelectrode studies of passive membrane properties and action potential generation were carried out on cloned and uncloned mouse neuroblastoma cells in tissue culture. The cloned cells were studied between the eighth and tenth months and the uncloned cells between the third and fifth weeks after primary dissociation. Electrophysiologic measurements of cell membrane properties were made by passing stimulating current pulses across the cell membrane from an intracellular microelectrode and recording simultaneously from the same electrode, by means of a bridge circuit, the changes in membrane potential. The range of responses to electrical stimulation varied from passive increases in membrane potential to repetitive firing of action potentials. A 20 fold range in spike generating capability was found. Passive membrane properties (membrane potential, specific membrane resistivity, and specific membrane capacitance) were similar to those of sympathetic neurons in intact preparations. Seventy‐nine percent of the cloned cell line compared to 94% of the uncloned line were capable of generating action potentials. Less than 2% of the cloned cells showed repetitive firing whereas 23% of the uncloned cells had this property. As in several types of normal neurons, the action potential mechanism was largely, although not completely, blocked by iontophoretic and bath applied tetrodotoxin.
Oxygen toxicity in a fission yeast
Authors: Vaughan Gerald L. 
Published: February 2005

AbstractContinuous exposure of synchronous cultures of Schizosaccharomyces pombe to 2.0 atmospheres oxygen beginning at any point in the first two‐thirds of the cell cycle prevented subsequent cell division. Similar exposure during the last one‐third of the cell cycle did not prevent cell division. The inhibition of division was totally reversible. Exposure to 2.0 atmospheres oxygen for 2.5 hours did not affect oxygen consumption. Oxygen at 1.0 atmospheres reduced growth rate and protein synthesis by 44%. Similar exposure to 1.0 atmospheres reduced transport of glycine‐14C, L‐leucine‐14C, and uracil‐14C by 95%, 73%, and 89% respectively. Analysis of the kinetics of uptake of these materials showed noncompetitive inhibition of transport by oxygen. The primary effect in rapidly appearing oxygen toxicity apparently involved interference with the transport capabilities of the cell membrane.
Mutation rate from asparagine requirement to asparagine non‐requirement
Authors: Morrow John 
Published: February 2005

AbstractThe mutation rate from asparagine requirement to asparagine non‐requirement has been measured using the Luria‐Delbrück Fluctuation test in the Walker 256 rat carcinosarcoma line grown in vitro. Non‐requiring variants are pre‐existing in the population, and are not induced by the selecting agent. The mutation rate was of the order of 1.4 × 10−6 per cell per generation to 3.5 × 10−6 per cell per generation. The relationship between the malignancy of the cell line and its unusual requirement for asparagine is discussed.
The biosynthesis of protamine during spermatogenesis of the mouse: Extraction, partial characterization, and site of synthesis
Authors: Lam D. M. K. , Bruce W. R. 
Published: February 2005

AbstractA highly basic, testis‐specific, chromosomal protein (MP) can be extracted with acid from testis cells of the mouse, but not from mature spermatozoa. A similar protein (MP') can be isolated from spermatozoa if they are first disrupted with β‐mercaptoethanol and urea. The two proteins (MP and MP') are identical as characterized by polyacrylamide gel electrophoresis, Bio‐Gel P‐10 chromatography, amino‐acid analysis and equilibrium ultracentrifugation. They are presumably mouse protamine. Both measurements of the sedimentation velocities of testis cells which synthesize mouse protamine and of the activity of spermatozoa after a pulse label with radioactive arginine show that protamine is synthesized 19 days after the last meiotic S‐phase, that is, at an advanced stage of spermiogenesis.
Photo‐reversal of the circadian rhythm in the proliferative activity of the mouse small intestine
Authors: Sigdestad Curtis P. , Lesher S. 
Published: February 2005

AbstractMice (C57Bl) were placed for 35 days in a room with reversed light cycle; lights came on at 1800 hours and off at 0600 hours. At six hour intervals throughout the day three mice were injected with tritiated thymidine and sacrificed 30 minutes later. Crypts were dissected for radioautography and determination of disintegrations per minute per crypt, the number of cells in mitosis and the number of cells synthesizing DNA was determined. The results reported clearly demonstrate reversal of the circadian rhythm in the parameters tested.
Mutation rates in cells at different ploidy levels
Authors: Harris Morgan 
Published: February 2005

AbstractFluctuation tests of the Luria‐Delbrück type have been used to examine the frequency of spontaneous variations in cultures of diploid, tetraploid, and octaploid Chinese hamster cells. Resistance to 8‐azaguanine and altered response to thermal shock were chosen as marker systems. Mutation frequencies of approximately 10−6 and 10−5 have been estimated for heat resistance and azaguanine resistance respectively. Rates of mutation for these markers remain constant or decline slightly in cells with increasing numbers of chromosome sets. This trend is not in accordance with expectations based on the assumption of dominant, co‐dominant, or recessive changes at gene or chromosome levels. It is suggested that at least some variations may arise in somatic cells by stable shifts in phenotypic expression rather than by changes in genetic information.
Age‐related changes in hematopoietic stem cell populations of a long‐lived hybrid mouse
Authors: Chen Michael G. 
Published: February 2005

AbstractAge‐related changes in the number and concentration of pluripotential and unipotential hematopoietic stem cells in the femoral bone marrow and spleen of BC3F1 mice were investigated. Pluripotential stem cells were assayed by the spleen colony technique, and unipotential stem cells were determined by an agar cloning method and by erythropoietin responsiveness in polycythemic mice. Changes with senescence were observed in the concentration of both uni‐ and pluripotential stem cells in the bone marrow; the size of the stem cell compartment in the marrow did not change significantly with age. Also, a reduction in the seeding of transplanted spleen colony‐forming units into the spleens of aged recipients was demonstrated. The implications of these findings for the kinetics of hematopoietic stem cell proliferation in aged animals are discussed.
Effect of 5‐bromodeoxyuridine on hyaluronic acid synthesis of a clonal hybrid line of mouse and Chinese hamster in culture
Authors: Koyama Hideki , Ono Tetsuo 
Published: February 2005

AbstractA clonal hybrid line, B‐6, derived from the fusion of mouse and Chinese hamster cell lines, has an inheritable ability to synthesize and secrete hyaluronic acid (HA). In order to elucidate the control mechanism of expression of this differentiated function, we studied the effect of 5‐bromodeoxyuridine (BUDR), a thymidine (TDR) analog on the growth and HA synthesis of this hybrid line. The presence of BUDR at 0.5–1 μg/ml of medium had no effect on cell multiplication, but reduced HA production by approximately 25 to 40%. Treatment with 5 to 25 μg/ml of the analog resulted in about 15% decrease of the total cell growth, or 30% decrease of the viable cell growth, while mucopoly‐saccharide production was reduced by more than 70%. These results indicate that BUDR affects HA synthesis more strongly than it does cell growth.Inhibition was found to be detectable after two days of culture with BUDR. This effect was prevented by the simultaneous addition of TDR in a concentration more than twice that of the analog. Furthermore the inhibitory effect was reversible, since a gradual but complete recovery of HA synthesis occurred after removal of BUDR from the medium. In contrast, the growth rate of B‐6 cells was discovered to be more sensitive than HA synthesis to the inhibitory action of either excess TDR or another analog, 5‐fluorodeoxyuridine (FUDR).
Cultures from adult rat liver cells I. Establishment of monolayer cell‐cultures from normal liver
Authors: Iype P. T. 
Published: February 2005

AbstractEstablishment of monolayer cell‐cultures from adult normal rat liver is described using cells isolated by a collagenase‐hyaluronidase perfusion technique. The cells plated originally were polygonal in shape and contained a large number of mitochondria. However, cells with less granules were also observed in the primary culture, after a few days of plating. In subsequent subcultures, the latter type of cells could be grown continuously. After an initial lag, the cells attained a doubling time of 55 hours and a plating efficiency of 20%. The cells are “normal” with respect to their karyology, morphology and growth pattern. Difficulties encountered during the culture and the possible uses of these cultured cells in studies on carcinogenesis in vitro are discussed.