bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of reduction of culture medium sodium, using different sodium chloride substitutes, on the proliferation of normal and rous sarcoma virus‐infected chicken fibroblasts
Authors: Balk Samuel D. , Polimeni Philip I. 
Published: February 2005

AbstractWe have substituted choline chloride, tetramethylammonium chloride, sucrose, or glucose for culture medium sodium chloride. When culture medium sodium is reduced below physiological levels (143 mM) by replacement of graded concentrations of sodium chloride with equivalent concentrations of choline chloride, normal fibroblasts approach proliferative inactivity in the presence of 90 mM Na, while their Rous sarcoma virus (RSV)‐infected counterparts proliferate actively; both normal and neoplastic cells die with further sodium reduction. When culture medium NaCl is replaced with tetramethylammonium chloride, however, both normal and RSV‐infected fibroblasts alike approach proliferative inactivity in the presence of 110 mM Na and both die off in the presence of 90 mM Na. When culture medium NaCl is replaced with sucrose or glucose yet another set of resuls is obtained: both normal and RSV‐infected fibroblasts proliferate at reduced, although significant, rates in the presence of 42 mM Na. It is clear from our experimental results that the effects of reduction of culture medium sodium on cell proliferation differ markedly with the use of different sodium chloride substitutes. Caution must be exercised, therefore, in drawing inferences concerning the role of sodium in mitogenesis from experimental studies based on the tactic of reduction of external sodium.
Effect of cocultivation of the levels of spontaneous and induced sister chromatid exchanges in chinese hamster cells
Authors: Rainaldi Giuseppe , Luccini Fulvio , Mariani Tullio 
Published: February 2005

AbstractThe level of sister chromatid exchanges, both spontaneous and induced by UV light or ethylmethanesulphonate (EMS), in Chinese hamster V79/AP4 cell line, is partially reduced upon cocultivation with human cells. Normal and xeroderma pigmentosum (XP) cells are equally effective. On the basis of these observations, cocultivation may represent a good tool for investigating the SCE's formation processes.
Multihormonal induction of α2u‐globulin in an established rat hepatoma cell line
Authors: Widman Lawrence E. , Chasin Lawrence A. 
Published: February 2005

AbstractA subclone of the FU5‐5 rat hepatoma cell line has been isolated which is inducible more than several hundred fold for the 20,000 dalton form of the major rat urinary protein α2u‐globulin. The basal relative synthetic rate (RSR) in growth medium containing 10% fetal calf serum was less than 2 × 10–6 of total protein synthesis. Both dexamethasone and insulin were necessary for induction, and yielded a maximum induced RSR of 4–8 × 10–3. Triiodothyronine (T3), dihydrotestosterone (DHT), rat growth hormone (GH), and estrogen, all of which have been shown to influence the induction of α2u–globulin in the intact rat, were without effect on the cell line. A factor present in fetal calf serum was also necessary for maximum induction, since dexamethasone plus insulin in serum‐free medium raised the RSR to only 3 × 10–5; exogenous T3, GH, and DHT could not substitute for this serum factor. The kinetics of induction by dexamethasone were slow, with a lag of approximately 48 hr followed by a period of increasing RSR for 6–20 days. Removal of dexamethasone from induced cells led to an exponential decline in the RSR (t½1/2 15 hr). The concentrations of dexamethasone and insulin that could yield half maximum induction were 5 × 10–8 M and 3 × 10–11M, respectively. Higher concentrations of insulin, although still in physiological range (10–9M), inhibited induction. At yet higher insulin levels, beyond the physiological range, α2u‐globulin synthesis returned to maximum values. The lack of DHT, T3, and GH requirement for α2u‐globulin induction in this cell line may mean that a regulatory aberrancy has occurred in this transformed cell line, or, alternatively, that these hormones act indirectly in the intact animal. This cell line should prove useful for the study of the molecular events associated with α2u‐globulin induction and for genetic approaches to the problem of multihormonal regulation of gene expression.
Immature megakaryocytes in the mouse: In vitro relationship to megakaryocyte progenitor cells and mature megakaryocytes
Authors: Long Michael W. , Williams Neil , McDonald Ted P. 
Published: February 2005

AbstractAn assay describing conditions for the maturation of single immature megakaryocytes in vitro is reported. Enriched populations of small, relatively immature megakaryocytes have been found to develop into single, mature megakaryocytes by 60 hours in semisolid agar cultures. Continued incubation of these cells did not lead to the formation of colonies within 5–7 days. Maturation was indicated by increasing cell size and cytoplasmic and acetylcholinesterase content. Factors stimulating the development of immature megakaryocytes were found in preparations of human embryonic kidney cell‐conditioned media (a source of in vivo Thrombopoietic Stimulatory Factor), peritoneal exudate cell‐conditioned medium, lung‐conditioned medium, or bone marrow cellular sources of activity (adherent cells or cells that sediment at 5–6 mm hr‐1). Immature megakaryocytes cultured serum free responded to sources of an auxiliary megakaryocyte potentiating activity by developing into single, large megakaryocytes but did not respond to a megakaryocyte colony‐stimulating factor devoid of detectable potentiator activity present in WEHl‐3‐conditioned medium. In contrast, serum‐free proliferation of the megakaryocyte progenitor cell required both megakaryocyte colony‐stimulating factor and the auxiliary potentiator activity. In the presence of megakaryocyte colony‐stimulating factor alone, progenitor cells did not form colonies of easily detectable megakaryocytes. However, groups of cells comprised entirely of small acetylcholinesterase containing immature megakaryocytes were observed, thus establishing that megakaryocyte colony development passes through a stage of immature cells prior to detectable megakaryocyte development and that some acetylcholinesterase‐containing cells can undergo cellular division.
Regulation of sugar transport in cultured diploid human skin fibroblasts
Authors: Germinario Ralph J. , Rockman Howard , Oliveira Maureen , Manuel Susannia , Taylor Melarie 
Published: February 2005

AbstractThe regulation of hexose transport under glucose‐starvation conditions was studied in cultured human skin fibroblasts. Glucose starvation enhanced the transport of 2‐DG and 3‐O‐methyl‐D‐glucose (3‐OMG) but not of L‐glucose. Glucose‐starvation enhanced transport was inhibited by cytochalasin B (10 μM). The starvation‐induced change in 2‐DG transport was due to an increase in the Vmax of both the high and low affinity transport sites (2.8‐ and 2.4‐fold, respectively) with no effect on their Kms. The presence of 5.55 mM galactose, fructose, or L‐glucose in the medium resulted in transport increases similar to those seen in glucose‐starved cells, while the presence of 5.55 mM glucose, mannose, or 3‐OMG repressed 2‐DG transport. Glucose‐starvation enhancement of 2‐DG transport was blocked by cycloheximide (20 μg/ml) but not by actinomycin D (0.03 μg/ml) or α‐amanitin (3.5 μM). Readdition of glucose (5.55 mM) for six hours to glucose‐starved cells led to a rapid decrease in hexose transport that could be blocked by cycloheximide but not actinomycin D. Although readdition of 3‐OMG to glucose‐starved cells had little effect on reversing the transport increases, glucose plus 3‐OMG were more effective than glucose alone. Serum containing cultures (10% v/v) of glucose‐fed or glucose‐starved cells exhibited rapid decreases in 2‐DG transport when exposed to glucose‐containing serum‐free medium. These decreases were prevented by employing glucose‐free, serum‐free medium. The data indicate that hexose transport regulation in cultured human fibrob asts involves protein synthesis of hexose carriers balanced by interactions of glucose with a regulatory protein(s) and glucose metabolism as they affect the regulation and/or turnover of the carrier molecules.
Regulation of hexose transport in BALB/c 3T3 preadipose cells: Effects of glucose concentration and 12‐O‐tetradeconoylphorbol‐13‐acetate
Authors: O'Brien Thomas G. , Saladik Douglas 
Published: February 2005

AbstractLike many cell types in culture, both undifferentiated and differentiated BALB/c 3T3 preadipose cells respond to glucose deprivation with an increased uptake of 2‐deoxy‐D‐glucose (deoxyglucose) and 3‐O‐methyl‐D‐glucose (methylglucose). Glucose readdition to glucose‐deprived cultures resulted in a prompt fall in uptake activity; in undifferentiated cells, a half‐maximally effective concentration of glucose was approximately 0.5 mM, while 0.1 mM was ineffective. Several hexoses differed in their efficacy of “deactivating” methylglucose transport in glucose‐deprived cells; it appeared that a particular hexose must be metabolized beyond the 6‐phosphate from to deactivate the transport system. Previous studies have shown that the phorbol ester 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) stimulates hexose transport in undifferentiated and differentiated BALB/c 3T3 cells. In this study, it was found that TPA (and insulin in differentiated cells) prevented the glucose‐induced deactivation of transport activity. Glucose‐induced deactivation of transport activity was also prevented by cycloheximide or actinomycin D addition concomitantly with glucose. In glucose‐starved cells, agents such as TPA and insulin appear to override a cellular control mechanism sensitive to the external concentration of glucose, so that elevated levels of transport activity are maintained under environmental conditions (i.e., a return to physiological glucose concentrations) that normally induce a fall in transport activity.
Regulation of Na+, K+ pump activity by nerve growth factor in chick embryo dorsal root ganglion cells
Authors: Boonstra Johannes , Skaper Stephen D. , Varon Silvio 
Published: February 2005

AbstractNerve growth factor (NGF) is required for the growth and development of sensory and sympathetic neurons. Incubation of chick dorsal root ganglionic cells without NGF resulted in a decrease of active (Na+, K+‐pump‐mediated) K+ influx over a period of several hours. Addition of NGF to NGF‐deprived cells caused (1) a return of the active K+ influx to the values occurring in cells continuously exposed to NGF, preceded by (2) a very rapid, but transient overstimulation of the Na+, K+‐pump‐mediated K+ influx. Restoration of normal Na+, K+‐pump activity occurred at NGF concentrations of 1 biological unit/ml or greater, whereas the NGF concentration in the 1–100 biological unit/ml range affected the rapidity with which the pump restoration took place. The transient pump behavior was only observed in NGF‐deprived cells and could not be elicited in NGF‐supported steady‐state cells or in cells having already received delayed NGF once. This transient Na+, K+‐pump behavior was exclusively displayed in conjunction with a high intracellular Na+ concentration. Decreasing the external Na+ concentration below 70 mM reduced the hyperstimulation response to NGF, until at 10 mM Na+ the delayed presentation of NGF caused no overshoot at all. The effect of NGF on the Na+, K+‐pump was specific for the NGF molecule and could not be mimicked by other proteins.
Temperature‐dependent alteration of cellular morphology by cholera toxin in rat liver epithelial cells which are TS for maintenance of transformed properties
Authors: Niles Richard , Loewy Barbara , Krah David 
Published: February 2005

AbstractCholera toxin via its ability to increase intracellular cyclic AMP levels can induce drastic changes in cell morphology. This report describes a temperature sensitive mutant of chemically transformed rat liver epithelial cells which only display cell shape alterations in response to cholera toxin at the permissive temperature. Shift up‐shift down experiments indicate that the change in the response occurs fairly rapidly, i.e., within 2 hours at the new temperature. The behavior of the temperature sensitive cells at the nonpermissive temperature mimics that of the untransformed rat liver epithelial cells (i.e., no morphological change in response to cholera toxin) while at the permissive temperature the positive cell shape change is identical to that exhibited by chemically transformed rat liver epithelial cells. The temperature sensitive response to cholera toxin is not a function of cyclic AMP production, since the amount of cyclic AMP found as a function of either time or concentration of cholera toxin is quite similar in cells treated at either temperature.
Induced release and metabolism of arachidonic acid from myeloid cells by purified colony‐stimulating factor
Authors: Ziboh Vincent A. , Miller Alan M. , Wu Ming‐Chi , Yunis Adel A. , Jimenez Joaquin , Wong Glen 
Published: February 2005

AbstractThe in vitro incubation of cells from turpentine‐induced rat myeloid hyperplastic marrow and peritoneal monocyte/macrophage with 14C‐arachidonic acid resulted in the incorporation of the radiolabel into the particulate phospholipids. Challenge of the radiolabeled cells with a highly purified type I CSF (CSF I) from human pancreatic carcinoma cells in continuous culture resulted in the hydrolysis and release of the 14C‐arachidonic acid from the cellular phospholipids. The simultaneous challenge of the prelabeled cells with CSF‐I and its specific antibody (anti‐CSF‐I antibody) inhibited the CSF‐I induced hydrolysis of 14C‐arachidonic acid from the cells. These results confer a specificity on the CSF‐I induced release of arachidonic acid from the cellular phospholipids. Our data also demonstrated that the 14C‐arachidonic acid released from the cellular phospholipids was further transformed into products of the cyclooxygenation and lipoxygenation pathways by cellular enzyme systems in both populations of cells. Interestingly, our data also indicate that the challenge of the granulocytic hyperplastic marrow cells and the monocyte/macrophage cells with purified CSF‐I resulted in a higher generation of lipoxygenase products in the predominantly granulocytic cell population than in the population rich in monocyte/macrophage cells. The biological significance of this observation remains to be further explored. Thus, the CSF‐I‐induced release of cellular arachidonic acid explains, at least in part, the presence of prostaglandins and other metabolites of arachidonic acid that are found in the media of hemopoietic cells incubated with a variety of CSF preparations.
Nuclear ligation of RNA polynucleotide kinase products
Authors: Winicov Ilga 
Published: February 2005

AbstractRNA polynucleotide kinase has been shown to transfer [γ32P] from ATP to 5‐OH termini of endogenous nuclear RNA. The products of this reaction have been isolated in RNA larger than 125 after in vitro incubation of mouse L cell nuclei. About 20%–30% of these 5′‐OH kinase products are polyadenylated. A sizeable fraction of the [γ32P] label from ATP is also found in internal phosphodiester bonds after 30‐minute nuclear incubation in vitro. The possibility of substantial [32P] recycling via the α position of nucleoside triphosphate was ruled out because: (1) 2mM nucleoside triphosphates in the incubation medium, (2) limited nearestneighbor distribution 3′ and 5′ to the phosphodiester bond compared with that from [α32P] UTP, (3) different nearest‐neighbor distribution for RNA molecules > 12S and 12‐3S, (4) relative insensitivity of the [γ32P] incorporation to α‐amanitin as compared with total RNA synthesis, (5) internal [32P] appearance in RNA > 12S in less than five minutes of incubation, and (6) < 0.03% to 0.6% of the total [32P] in the α position of nucleoside triphosphates after 30 minutes of incubation. The [γ32P] incorporation was dependent on high ATP concentration and was insensitive to competition by inorganic phosphate. These results are consistent with the levels of 5′ RNA polynucleotide kinase activity in L cell nuclei and suggest the presence of an RNA ligase that can utilize the termini generated by the 5′‐OH RNA kinase in a ligation reaction.
The prolongation of mitotic stages in SV40‐transformed vs nontransformed human fibroblast cells
Authors: Sisken Jesse E. , Bonner Susan V. , Grasch Sally D. 
Published: February 2005

AbstractEarly studies on the duration of mitotic stages and on metaphase‐to‐prophase ratios in a number of normal and neoplastic cells indicated that the process of mitosis becomes altered during the course of oncogenesis. However, the nature of these changes and their effects on each of the mitotic stages are still unclear. With the use of time lapse cinemicrography, we have compared the durations of mitotic stages of SV40/Wl‐38 and SV40/Wl‐26 cells to those of their normal counterparts and to other nontransformed human fibroblasts. We also examined the relative frequencies of the individual mitotic stages in fixed preparations of Wl‐38 and SV40/Wl‐38 cells. The data show that metaphase durations are increased in the transformed cells and as much as 3‐4.7‐fold in SV40/Wl‐38 cells compared to Wl‐38 and other nontransformed cells. Other stages are also prolonged though to lesser degrees. These findings suggest that increased metaphase/prophase ratios observed in many tumors are due to increases in duration of metaphase rather than to shorter prophases, and that increased mitotic indices commonly observed in malignant tumors and sometimes used as an index of growth rate are at least in part due to the prolongation of mitotic stages.
Glucose metabolism, insulin effects, and developmental age of cultured neonatal rat heart cells
Authors: Schroedl Nancy A. , Hartzell Charles R. , Ross Philip D. , McCarl Richard L. 
Published: February 2005

AbstractCultured heart cells from 2–3 day old and 5–6 day old neonatal rats have been used as a model system for the characterization of carbohydrate metabolism in developing cardiac tissue. The rate of depletion of glucose from the growth medium was dependent on (1) the age of the animals from which the cultured cells were obtained, and (2) the presence and absence of serum and/or insulin in the growth medium. The glucose depletion rate in insulin and serumcontaining medium was 9.63 ± 0.96 nmol/min/mg protein for heart cell cultures from, 2 day old rats and 3.51 ± 0.68 nmol/min/mg protein in heart cell cultures from 5 day old rats. Appearance of lactate in the medium during these experiments occurred at the rates of 18.6 ± 7.9 nmol/min/mg and 6.4 ± 1.2 nmol/min/mg, respectively. In the absence of serum and insulin, the medium glucose depletion rates were 5.7 ± 1.6 and 2.2 ± 0.5 nmol/min/mg for cells derived from 2‐day‐old and 5‐day‐old rats, respectively. It is apparent from these data that immature cardiac cells depend upon glucose as a primary source of energy for muscle contraction and cellular growth, and that less‐efficient energy‐yielding metabolic pathways are used to obtain ATP.
The competitive ability of stem cells from mice with Hertwig's anemia
Authors: Barker Jane E. , McFarland Eleanor C. , Bernstein Seldon E. 
Published: February 2005

AbstractMice homozygous for the gene, an, have a macrocytic, normochromic anemia. In this report, attempts have been made to cure Hertwig's anemia (an/an) by injecting genetically normal (+/+) stem cells. The anemia of unirradiated an/an mice was alleviated but not completely cured by injection of as many as 3 × 107 +/+ bone marrow cells. Lethal irradiation of the an/an recipients was necessary before injections of 107 +/+ marrow cells were effective in normalizing the blood parameters. The inability to achieve normal blood values without first destroying the host's own stem cells suggested that the indigenous an/an cells compete effectively with injected +/+ cells. This hypothesis was tested by injecting varying numbers of stem cells from C57BL/6J‐ +/+ mice, together with stem cells from either WBB6F1‐an/an or, as controls, from their WBB6F1‐ +/+ littermates, into lethally irradiated hosts. The C57BL/6J and WBB6F1mice have electrophoretically distinguishable hemoglobins. The an/an cells are able to compete in the repopulation of the host hematopoietic tissue as shown by the presence of WBB6F1 hemoglobin in the recipients. The cells from mice with Hertwig's anemia, however, do not compete as effectively as do the same number of cells from the +/+ littermates. These results indicate that the pluripotent hematopoietic stem cells of an/an mice are reduced in number, seeding capacity, or proliferative potential.
Low‐frequency voltage noise in a mammalian bone cell clone
Authors: Ferrier Jack , Dixon Jeff , Illeman Alan , Dillon Eva , Smith Inka 
Published: February 2005

AbstractMeasurements were made of plasma membrane voltage noise in cells of a bone cell clone. The measurements were made under conditions intended to approximate in vivo conditions more closely than in previous electrical measurements on small mammalian cells. Mononuclucell of normal size, imbedded in a collagen matrix, were used. The electrical state of the cell membrane under normal conditions was characterized by low‐frequency random fluctuations (noise) of high magnitude. Hyperpolarizing spikes were observed in some cells. Power spectrum analysis revealed that the random fluctuations were actually a sum of incoherent spike patterns, with spikes of the same time width as those seen in the clearly spiking patterns. This analysis, combined with similar measurements in a high [K+], low [Na+] medium, showed that the fluctuation/spiking phenomenon resulted from modulation of K+ and Na+ transport by a control process at a level higher that that of the individual channels. This process persisted when the membrane potential was depolarized. These results indicate that the membrane potential is not part of the feedback loop producing the fluctuation/spiking phenomenon.
Lens epithelial cell adhesion to lens capsule: A model system for cell‐basement membrane interaction
Authors: Cammarata Patrick R. , Spiro Robert G. 
Published: February 2005

AbstractAdhesion of calf lens epithelial cells to lens capsule, their natural basement membrane was found to be considerably more rapid than either to plastic or to type I or type IV collagen coated surfaces. No polarity of the basement membrane was observed as the cells were able to attach to either side of the anterior or posterior lens capsule; a prerequisite for adhesion to the lenticular side of the anterior capsule was the prior removal of its epithelial cell layer. The attachment was energy‐dependent and required calcium and magnesium ions, but was not enhanced by the presence of serum. Neither exogenous fibronectin nor laminin was able to stimulate attachment or spreading of lens cells to the capsule even when the cells had been treated with cycloheximide. Since rapid adhesion and spreading takes place in this lens cell‐lens capsule system without requirement of exogenous macromolecules, it provides a favorable model for investigating the determinants in epithelial cell‐basement membrane interactions.