bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECT OF AN INHIBITING FACTOR ISOLATED FROM RAT LIVER ON DNA POLYMERASES IN REGENERATING RAT LIVER
Authors: Pietu G. , Munsch N. , Mousset S. , Frayssinet C. 
Published: May 2008

ABSTRACTWe partially purified an inhibitory factor (LIF), isolated from 105,000 g supernatant of a saline adult rat liver homogenate. LIF stopped in vitro cell multiplication by blocking the G1—S transition, and reduced in vivo [3H]thymidine incorporation into liver DNA in two‐thirds hepatectomized rats. This reduction in DNA synthesis was observed at 24 hr after hepatectomy, even when the LIF was injected before the beginning of the S phase, 10 hr after hepatectomy, i.e. when DNA polymerase activity had not yet increased. Under these experimental conditions, LIF in vivo treatment prevented α DNA polymerase activity from increasing after partial hepatectomy, so that enzyme activity at 24 hr in LIF‐treated rats decreased compared to the controls. No direct inhibitory effect of LIF on α DNA polymerase was detected. LIF did not affect β DNA polymerase.These results suggest that LIF plays a part in controlling liver growth.
CELL POPULATION KINETIC PROFILE OF THE MOUSE THYMUS, AND THE CHANGES INDUCED BY PREDNISOLONE
Authors: Zaitoun A. M. , Lauder I. , Aherne W. A. 
Published: May 2008

ABSTRACTThe cell population kinetic parameters of the thymus in BALB/c mice have been estimated using stathmokinetic and [3H]TdR techniques in both control animals and animals treated with prednisolone. FLM data were analysed by computer using the Gilbert program. The study showed that prednisolone had an inhibitory effect mainly in the DNA synthesis phase and in G1. Stathmokinetic data also showed a decrease in the cell birth rate and an increase in the apparent cell cycle time (or potential doubling time) after treatment. The labelling index, the mitotic index and the growth fraction were also decreased. The study also shows a good agreement between the data obtained by stathmokinetic and [3H]TdR techniques.
A NEW METHOD FOR THE ESTIMATION OF CELL CYCLE PHASES
Authors: Zajicek G. , Michaeli Y. , Regev J. 
Published: May 2008

ABSTRACTA method is described, which is applicable to cell renewal systems with an anatomical structure in which all cell locations may be uniquely mapped. Its use is demonstrated on the rat incisor inner enamel epithelium, which forms a one cell thick column in the sagittally sectioned tooth. Cells born in the apical part of the column migrate toward the distal end of the tooth, where they mature. As the cells migrate along the column, they traverse the various cell cycle phases.The present study has been designed to estimate the probability of a cell being in a given phase; all cells touching the basement membrane were numbered, and the number of cells separating any two cells was taken as a measure of distance. Since generally all cells move in one direction (lateral cell migration may occur), it is possible to solve the problem with the aid of functions describing the renewal counting stochastic process in which cell distance serves as an independent variable.The method predicts labelled cell and mitotic rates which agree with those estimated in the usual way. It was then utilized to estimate the fraction of cells in G2.
FURTHER STUDIES ON MOBILIZATION OF CFUs
Authors: Vos O. , Wilschut Ina J. C. 
Published: May 2008

ABSTRACTMobilization of CFUs from haemopoietic tissues into circulation was studied after injection of different bacterial lipopolysaccharides (LPS), zymosan, phytohaemagglutinin (PHA), concanavalin A (Con A), trypsin and di‐isopropyl‐fluorophosphate‐inhibited trypsin. All bacterial LPS used gave an increase of CFUs in the peripheral blood at 1 h after i.v. injection. Some variation in activity could not be excluded. As with Salmonella typhosa LPS, zymosan gave an increase in circulating CFUs during the first few hr and a second peak a few days later. After injection of zymosan as well as S. typhosa LPS the second peak in the blood was accompanied by a large increase in CFUs numbers in the spleen. PHA gave an immediate mobilization of CFUs, but the mobilization after injection of Con A during the first few hr occurred more slowly. After injection of S. typhosa LPS, zymosan and PHA the blood C3 level was found to be depressed considerably. This might indicate that the complement system is involved in the early mobilization of CFUs.Dexamethasone, a synthetic hormone which has been reported to give sequestration of several cell types in the bone marrow, did not inhibit the early and late mobilization of CFUs which normally occurs after injection of S. typhosa LPS.
CIRCADIAN RHYTHMS IN MOUSE EPIDERMAL BASAL CELL PROLIFERATION
Authors: Clausen O. P. F. , Thorud E. , Bjerknes R. , Elgjo K. 
Published: May 2008

ABSTRACTSeveral kinetic parameters of basal cell proliferation in hairless mouse epidermis were studied, and all parameters clearly showed circadian fluctuations during two successive 24 hr periods. Mitotic indices and the mitotic rate were studied in histological sections; the proportions of cells with S and G2 phase DNA content were measured by flow cytometry of isolated basal cells, and the [3H]TdR labelling indices and grain densities were determined by autoradiography in smears from basal cell suspensions. The influx and efflux of cells from each cell cycle phase were calculated from sinusoidal curves adapted to the cell kinetic findings and the phase durations were determined.A peak of cells in S phase was observed around midnight, and a cohort of partially synchronized cells passed from the S phase to the G2 phase and traversed the G2 phase and mitosis in the early morning. The fluctuations in the influx of cells into the S phase were small compared with the variations in efflux from the S phase and the flux through the subsequent cell cycle phases. The resulting delay in cell cycle traverse through S phase before midnight could well account for the accumulation of cells in S phase and, therefore, also the subsequent partial synchrony of cell cycle traverse through the G2 phase and mitosis. Circadian variations in the duration of the S phase, the G2 phase and mitosis were clearly demonstrated.
NON‐RANDOM ASSOCIATION OF MITOTIC CELLS FROM CULTURED HUMAN LYMPHOCYTE SUSPENSIONS
Authors: Fitzgerald P. H. 
Published: May 2008

ABSTRACTBy using chromosome markers in two separate cell lines of a human dispermic chimera, it was shown that 4.9% of metaphases in suspensions of PHA‐cultured lymphocytes were paired because of non‐random factors. A similar amount of metaphase pairing occurred in cultured lymphocytes of normal donors, and evidence from the relative mitotic cycles of the paired cells indicated that some of this pairing was non‐random. Such non‐random pairing could be a source of bias in cell kinetic and other studies involving metaphase cells in lymphocyte cultures.
INTERFERENCE OF SEX‐RELATED FACTORS IN THE RESPONSE OF LIVER CELLS TO EXPERIMENTAL MITOTIC STIMULI
Authors: Lombard M.‐N. , Nadal C. , Fiszer‐Szafarz B. , Rumeur E. Le , Zajdela F. 
Published: May 2008

ABSTRACTStimulation of liver cell multiplication was obtained under two different experimental conditions.

A single injection of casein solution resulted in (a) an identical synchronized mitotic wave response in 10‐day old male and female rats and (b) a significantly lower response in adult male rats compared to females, a difference which was reduced by castration of males at birth but essentially maintained if animals were operated when 10 days old.
Partial hepatectomy shortly after puberty resulted in active hepatocyte multiplication occurring 3 hr earlier in females than in males. This difference was suppressed when females were ovariectomized at birth and significantly reduced when they were spayed at a later age. Hepatocytes of castrated females entered actively into S phase 2 hr later than the sham‐operated controls. Unilateral ovariectomy on the other hand indicated that during compensatory and/or hyper‐compensatory activity of the single ovary there was a maximum difference between the male and female rate of [3H]thymidine uptake in liver nuclei 20 hr after hepatectomy. A further kinetic study (t= 25, 30, 40, 65, 90 hr) indicated no significant sex‐related difference in the number of S phases per 10,000 cells.

The DNA content of regenerating versus control livers was comparable in both sexes at t= 22 and 90 hr but higher in females at t= 40 and 65 hr.A possible early postnatal interference of certain hormonal mechanisms in the receptivity to mitotic stimuli is postulated and discussed.
ALTERATION OF NEONATAL RAT PAROTID GLAND ACINAR CELL PROLIFERATION BY GUANETHIDINE‐INDUCED SYMPATHECTOMY
Authors: Klein R. M. 
Published: May 2008

ABSTRACTNewborn rats were injected with guanethidine‐sulfate (20 μg/g body weight) every 48 hr from 12 hr after birth until day 14 (eight injections per animal). The guanethidine treatment resulted in an 86% absolute reduction in cell number in the superior cervical ganglia of 15 day old rats. The cells which remained after guanethidine treatment showed destruction of mitochondria and an extensive decrease in endoplasmic reticulum. Chemical sympathectomy with guanethidine induced a 3.1 hr lengthening of the acinar cell generation cycle time (17.4 hr to 20.5 hr), resulting from a longer G1 period (6.9 hr in the control group as compared to 10.5 hr in the guanethidine‐treated group), as well as a decrease in the mean percentage of [3H]thymidine‐labeled acinar cells (22.3 ± 0.5% to 19.3 ± 0.5%) and mean acinar cell mitotic index (2.6 ± 0.2% to 2.1 ± 0.1%). A circadian rhythm was found to exist in parotid gland acinar cell mitotic activity of 15 day old rats and the amplitude of the rhythm was reduced from 26.5% to 14.9% in guanethidine‐treated rats. This study indicates that the diminution of sympathetic influence on the developing parotid gland results in a slight, but significant alteration in acinar cell proliferation.
LOW LEVEL INCORPORATION OF TRITIATED THYMIDINE INTO THE NUCLEAR DNA OF PURKINJE NEURONS OF ADULT MICE
Authors: Cameron I. L. , Pool Mary R. H. , Hoage T. R. 
Published: May 2008

ABSTRACTAdult mice were pulse labeled with tritiated thymidine [3H]TdR and killed 9 hr later. A low level incorporation of [3H]TdR into the nuclear DNA of Purkinje neurons was found in autoradiographs. Enzymatic digestions with DNase and with RNase in combination with autoradiographic grain counts indicate that a portion of nuclear DNA is not stable in the Purkinje nucleus. These results are discussed in light of reports of the stable nature of DNA in Purkinje neurons of adult mice.
ON THE PROGENITOR CELL MIGRATION VELOCITY
Authors: Zajicek G. , Michaeli Y. , Regev J. 
Published: May 2008

ABSTRACTAn attempt is presented to extract cell kinetic information from histomorphological features. It is applicable to rapidly proliferating tissues like the intestinal epithelium. Each replicating tissue has an origin where cells are formed and a periphery toward which cells migrate. The migration path along which they move is denominated as tissue radius on which all cell positions are mapped. Cell migration on the radius is associated with cell proliferation at tissue origin. Each mitosis there is associated with the displacement of all cells distal to it by one cell position. The more mitoses positioned between a cell and tissue origin, the greater its migration velocity. It is possible therefore to derive the cell migration velocity v(x) from the cumulative mitotic distribution on the radius, N(x). v(x) = N(x)/tm (tm= mitotic time). In this form v(x) represents also cell production at any point on the radius and may serve for the computation of other cell kinetic parameters like generation time.These arguments are illustrated on the rat incisor tooth inner enamel epithelium which has been studied in the normal and rapidly erupting tooth.
LIMITATIONS IN THE USE OF [3H]THYMIDINE INCORPORATION INTO DNA AS AN INDICATOR OF EPIDERMAL KERATINOCYTE PROLIFERATION IN VITRO
Authors: Davison P. , Liu S. , Karasek M. 
Published: May 2008

ABSTRACTThe validity of using the incorporation of [3H]thymidine into DNA as an indicator of epidermal keratinocyte proliferation in vitro has been investigated. Other parameters of cell proliferation, direct count of cell number and measurement of DNA content, consistently fail to correlate with changes in [3H]thymidine incorporation into DNA in primary and first passage cultures of rabbit and human epidermal keratinocytes. Maximum incorporation of [3H]thymidine precedes the active growth period by three days. Incorporation declines markedly during the proliferative period. Thymidine kinase activity decreases during the proliferative growth phase.Incorporation of another pyrimidine nucleotide precursor, [14C]aspartic acid, suggests that in epidermal keratinocytes in vitro the extent of utilization of the salvage and the de novo pathways may be inversely related. In such cases [3H]thymidine incorporation into TCA precipitable material fails to reflect accurately cell proliferation.
VARIABILITY OF CELL GENERATION TIMES IN A HEPATOMA CELL PEDIGREE
Authors: Van Wijk R. , Van De Poll K. W. 
Published: May 2008

ABSTRACTTime‐lapse cinematographic analysis of a clone of HTC rat hepatoma cells showed variations in interdivision time within the clone. A positive correlation was found between the interdivision times of mother and daughter cells. The variability of the differences between interdivision times of cells of sister, cousin, second cousin or second‐second cousin relationship was calculated. The proportion of cells with large differences in intermitotic times was found to increase with decreasing relationship. The clonal division pattern observed suggests strongly that ‘inherited’factors govern the process leading to cell division but that their effects can be modified.
CELL‐PRODUCTION RATES ESTIMATED BY THE USE OF VINCRISTINE SULPHATE AND FLOW CYTOMETRY I. AN IN VITRO STUDY USING MURINE TUMOUR CELL LINES
Authors: Barfod I. H. , Barfod N. M. 
Published: May 2008

ABSTRACTA method for the evaluation of cell‐production rates is described which combines flow cytometry (FCM) and the stathmokinetic method.By means of FCM it is possible to estimate the distribution of cells with G1, S and (G2+ M) DNA content in a population. As this method gives the relative (G2+ M) DNA content of cells within the cell cycle, it may be possible to evaluate cell‐production rates by this technique.In the present study it was found that administration of a metaphase‐arresting (stathmokinetic) agent, vincristine sulphate (VS), to asynchronous cell populations of three different murine tumour cell lines in vitro increased the peak representing cells with (G2+ M) DNA content as the number of mitotic (M) cells increased during the period of treatment.The accumulation of mitotic cells was determined by cell counts on smears under the microscope and compared with the increase in the (G2+ M) DNA peak measured by FCM as a function of time after the administration of VS. Good agreement was obtained between the cell‐production rates as estimated by FCM and by mitotic counts in all three cell lines investigated.
KINETICS OF HUMAN LYMPHOCYTE RESPONSES IN VITRO: DETERMINATION OF CLONE SIZE AND INITIAL RATE OF ENTRY INTO DNA SYNTHESIS
Authors: O'Leary J. J. , Hanrahan L. R. , Mehta C. , Rosenberg A. 
Published: May 2008

ABSTRACTIn this third paper on the kinetics of lymphocyte stimulation we present a simple stochastic model for the entry of mitogen stimulated human lymphocytes into the proliferative cycle. The model is based on the assumption that responder ‘recruitment’ is a process of simple exponential decay. The model can be applied to the initial rapid rise in thymidine uptake after stimulation and successfully predicts the behavior of colchicine inhibited mitogen responses. Application of the model allows the estimation of the following constants; the size of the responding clone, the rate of entry of committed cells into the initial cell cycle, the duration of the lag period before uptake of thymidine increases above background and the average duration of thymidine uptake in responding lymphocytes (Ts).If we analyze the experimental results of mitogen stimulation experiments in these terms we can show that the first three constants are sensitive functions of both the dose of mitogen and the source of the responding lymphocytes. The most interesting finding may be the fact that low doses of mitogen seem to decrease the rate of entry of committed lymphocytes into cell cycle. This would imply that the rate determining step in this process is not of an all or none type.
KINETICS OF CELL PROLIFERATION IN THE PRE‐IMPLANTED MOUSE EMBRYO IN VIVO AND IN VITRO
Authors: Streffer C. , van Beuningen D. , Molls M. , Zamboglou N. , Schulz S. 
Published: May 2008

ABSTRACTThe cell proliferation of pre‐implanted mouse embryos was investigated after development in vivo and in vitro. The studies were started at the pronuclear stage, 2 h post conception (p.c.) and continued until the hatching of blastocysts, 120–144 h p.c.The number of cell nuclei, the DNA content of each nucleus, the mitotic index and the labelling index were determined. From these data it was possible to calculate the length of the cell generation cycle and its various phases. With the exception of the first cell cycle the S‐phase was constant. The G1‐ as well as the G2‐phase varied in length during the different cell cycles.From 31–72 h p.c. the increase in cell number was exponential. After cultivation in vitro this increase was smaller than in vivo. At later periods the proliferation rate decreased with proceeding development. In late blastocysts most of the cells were in the G1‐phase. The development of the embryos was somewhat faster in vivo than in vitro. But in principle conditions were comparable.
EFFECT OF BLEOMYCIN ON MOUSE HAEMOPOIETIC COLONY FORMING CELLS IN CULTURE (CFUc)
Authors: Briganti G. , Levi G. , Spalletta E. , Galloni L. , Mauro F. 
Published: May 2008

ABSTRACTThe kinetics of CFUc studied by hydroxyurea and endotoxin treatments indicate that this cell population is proliferating actively (some 50% in S‐phase). This fact implies a peculiar response to (BLM) treatment with Bleomycin, a drug which appears to be proliferation—dependent. The dose—response has a steep initial slope resulting in a low extrapolation number (n= 0·66; D37 = 960 ± 70 mg BLM/kg body weight). The steep initial slope is confirmed by split‐dose experiments resulting in a potentiation effect by fractionation. Further evidence for the dependence of the action of this drug upon the proliferative state of the cell population is derived from time—response studies after single doses of BLM.
EXISTENCE OF AN ENDOGENOUS INHIBITOR OF DNA SYNTHESIS IN RABBIT SMALL INTESTINE SPECIFICALLY EFFECTIVE ON CELL PROLIFERATION IN ADULT MOUSE INTESTINE
Authors: Sassier P. , Bergeron M. 
Published: May 2008

ABSTRACTAqueous extracts from rabbit organs were prepared by homogenization and centrifugation at 105,000 g. After precipitation with ammonium sulphate, the 0–50 fraction was separated by ultrafiltration through Amicon XM 100 and XM 300 membranes yielding two filtrate fractions (U1 and U2) and one retentate fraction (U3). Only U1 and U3 inhibited thymidine incorporation into DNA. After a single injection of U1 from rabbit small intestine, the uptake of tritiated thymidine was decreased in mouse jejunal and colonic DNA. This effect, totally reversible after 7 hr, was found in neither the kidney nor the testis. The U1 fractions of colon and non‐digestive organs (kidney, testis) were found not to exert a significant inhibition on thymidine incorporation into intestinal DNA in vivo. The U3 fraction from rabbit small intestine also decreased the uptake of tritiated thymidine in mouse jejunal and colonic DNA in vivo. However, this inhibition was irreversible and not tissue‐specific.Slowing of cell migration was also noticed in the jejunum of mice injected with U1 or U3, as ascertained radioautographically by determining the position of the leading edge of the labelled cells in U1‐ or U3‐injected mice compared with controls. A decrease of mitotic activity in U1‐ and U3‐injected mice was recorded 8·5 hr after a single injection of small intestinal fractions.Our results suggest that U1 and U3 from rabbit small intestine contain one or more substances which may act on the G1—S transition of the cell cycle in the mouse intestine. However, only the effect of U1 is reversible and tissue specific. Our data suggest the existence of a factor, having a low molecular weight, which regulates intestinal cell proliferation.
A SIMPLIFIED METHOD OF DNA DISTRIBUTION ANALYSIS
Authors: Dean P. N. 
Published: May 2008

ABSTRACTCurrent methods of analysing DNA distributions utilize complex mathematical expressions that require the use of large non‐linear curve fitting methods and, consequently, large computers. This paper presents a new method of analysing DNA distributions of asynchronously growing or mildly perturbed cells. The S phase fraction is obtained by fitting a second degree polynomial to that part of the distribution, mid S phase, which is not influenced by either the G1 or the G2+ M peaks. The method is simple and fast, it exceeds the accuracy of other methods and it can be used on a large desk calculator or mini‐computer.
A CRITICAL REVIEW OF THE USE OF VINCRISTINE (VCR) AS A TUMOUR CELL SYNCHRONIZING AGENT IN CANCER THERAPY
Authors: Camplejohn R. S. 
Published: May 2008

ABSTRACTVincristine (VCR) has been used clinically in so‐called ‘tumour cell synchronization therapy schedules'. These schedules are based on the assumption that cells, arrested in metaphase by low doses of VCR, subsequently re‐enter the proliferative cycle synchronously. However, the evidence that tumour cell synchrony can be achieved under clinical conditions or that ‘cell synchronization therapy schedules’ yield a better therapeutic response than other efficient combination schemes, is scanty. Further, even in experimental systems, the efficacy of VCR as a cell synchronizing agent is disputed. Indeed, in some systems, cells arrested in metaphase by low doses of VCR, do not re‐enter a normal proliferative cycle at all following arrest. In addition, the complex nature of the VCR—tumour interaction and the heterogeneous nature of the tumour cell populations against which it is used augurs badly for the successful application of cell synchronization therapy schedules.
RENEWAL OF TASTE BUD CELLS IN RAT CIRCUMVALLATE PAPILLAE
Authors: Farbman A. I. 
Published: May 2008

ABSTRACTThe life span of taste bud cells in rat circumvallate papillae was measured by autoradiography after labeling them with a pulse of [3H]thymidine. Specimens of circumvallate papillae were taken daily 1·5‐18·5 days after the isotope was administered; thereafter, specimens were taken on alternate days until 25·5 days. For each time interval, the number of labeled cell nuclei was counted in 200‐450 taste buds and plotted as the ratio of labeled cells/taste bud v. time after injection of [3H]TdR. In all, 6958 taste buds were counted.The total number of labeled cells (dark plus light) per taste bud reached peaks at 6·5, 13·5 and 20·5 days. The curve for the number of labeled dark cells/bud had essentially the same shape as that for total cells. The number of labeled light cells/bud reached a modest peak at 6·5 days and slowly declined to a plateau for the remainder of the experiment. The data show that an average of 2 days elapsed after injection before labeled dark cells entered the bud and they spent an average of 7 days in the non‐proliferating taste bud compartment; thus, the life span of the dark cell was 9 days. The life span of the light cell was difficult to estimate quantitatively, but this cell type was labeled at a much slower rate than dark cells and is assumed to have a significantly longer tenure in the taste bud.