bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cell kinetics of hypoxic cells in a murine tumour in vivo: flow cytometric determination of the radiation‐induced blockage of cell cycle progression
Authors: Rutgers Derk H. , Niessen Dorien P. P. , van der Linden Pieter M. 
Published: May 2008

Abstract. Cells from the small cell population of viable cells in the large necrotic centre of murine M8013 tumours were investigated with respect to their cell kinetics. Flow cytometry (FCM) of this part of subcutaneously transplanted tumours revealed the presence of tumour cells with G1, S and G2 + M phase DNA‐contents. These severely hypoxic cells could have stopped cell cycle progression due to the nutritional deprivation, irrespective of their position within the cell cycle.Labelling methods, used to disclose the cell kinetics of this cell population, are hampered by the absence of a transport system in these large necrotic areas. Therefore, FCM was used to monitor radiation‐induced changes in the cell cycle distribution. From this investigation it was concluded that hypoxic cells in the necrotic centre of the M8013 tumour progress through the cell cycle. As well as a cell population with a cell cycle time (Tc) of approximately 84 hr, a subpopulation with a Tc of approximately 21 hr occurred.
Proliferation kinetics of plasma cells and of normal haemopoietic cells in multiple myeloma
Authors: Ucci G. , Riccardi A. , Dörmer P. , Danova M. , Luoni R. , Montecucco C. M. , Ciotti R. , Girino M. 
Published: May 2008

Abstract. DNA synthesis time (Ts) and 3H thymidine (TdR) labelling index (LI) of bone marrow (BM) myelomatous plasma cells (PC) and of the residual haemopoietic cell population (RHCP) were measured by in vitro quantitative 14C‐TdR autoradiography in five patients with multiple myeloma (MM) in different phases of disease (three at presentation and two at relapse) and in one patient with solitary extra‐osseous myeloma. One other patient with plasma cell leukaemia (PCL) was studied during an initial relapse phase and later during the leukaemic terminal phase. PC Ts was 18.8 ± 3.7 (from 13.3 to 25.0) hr and PC LI was 2.5 ± 1.8%; (from 1.0 to 6.3%). In the case of PCL, circulating PC had a Ts of 14.4 hr and a LI of 3.1. From these experimental measurements, the fractional turnover rate (FTR—percentage of cells produced per unit time) and the potential doubling time (Td) of BMPC were calculated assuming that all BMPC were in a steady‐state at the time of the study. BMPC FTR was 3.53 ± 2.3% cells per day (from 1.2 to 6.72) and BMPC Td was 46.8 ± 27.5 days (from 15.0 to 75.4). Comparison with results obtained in BM blasts of children with acute lymphoblastic leukaemia (ALL) indicated that BMPC had a lower proliferative activity (P < 0.001), although BMPC Ts was not significantly different. In two patients a tumour doubling time of 6 and 13 months was determined by clinical follow up. Comparison of this parameter with Td showed a cell loss factor of more than 90% in both patients.Kinetic data relative to RHCP showed slight variations with respect to those found in normal subjects, with a general tendency towards a prolongation of Ts and a reduction of LI.
A technique to analyse the emerging zonality of heterogeneous solid tumours
Authors: Michelson S. , Leith J. T. , Glicksman A. S. 
Published: May 2008

Abstract A technique to analyse the time‐dependent emergence of homogeneous regions composed of cells from a single clone within an artificial (clonally) heterogeneous tumour is described. Neoplasms were grown in vivo as xenografts made from varying proportions of the dichotomous subpopulations (Clones A and D). They were sampled frequently for volume and composition. A variable number of tumour cross‐sections were taken as part of the sampling technique. The random subsamples obtained from each cross‐section were enzymatically disaggregated into single cells. From the single cell disaggregates the composition of the tumours was estimated. An estimator for the global proportion of cells was then calculated from all the single cell disaggregates. Time‐dependent changes in the overall composition of the tumour requires that a time‐dependent estimate of the global proportions of the subpopulations be calculated from each sample. Analysis of the sample proportions results in a statistic which can be tested for goodness‐of‐fit against a standardized normal variate as a test of emerging zonality.Data from three artificial admixtures were examined. The results show that ‘zonality’, i.e. regions composed primarily of single subpopulations, emerges in all cases. However, the rate at which the zones emerge appears to depend on the ‘compositional stability’.Robustness studies show that the technique is robust with respect to the global estimator of the proportion.
Sensitivity of flow cytometric data to variations in cell cycle parameters
Authors: Ubezio P. , Rossotti A. 
Published: May 2008

Abstract We investigated to what extent flow cytometric DNA histograms are informative of cell cycle parameters. We created a computer program to simulate cell cycle progression in a generic and flexible way. Various scenarios, characterized by different models and distributions of cell cycle phase transit times, have been analysed in order to obtain the percentages of cells in the different cell cycle phases during exponential growth and their time course after mitotic block.Cell percentages during exponential growth were insensitive to intercell variability in phase transit times and thus can be employed to estimate the relative mean phase transit times, even in the presence of non‐cycling cells. However, this information is ambiguous if re‐entry of such cells into the cycling status is permitted. The stathmokinetic outline gives the mean phase transit times, but also provides information about the spread, but not the form, of the phase transit time distributions, being particularly sensitive to the spread of G1 phase duration. The stathmokinetic outline also helps distinguish between scenarios considering only cycling cells, those forecasting a fraction of definitively non‐cycling cells and those admitting a Go status with first‐order output kinetics.
Circadian Rhythms Are Suppressed In Hyperproliferative Mouse Epidermis
Authors: Brown W. R. , Furukawa R. D. , Ramsay C. A. 
Published: May 2008

ABSTRACTWe examined the chronically hyperproliferative epidermis of the asebia (ab/ab) mouse for circadian rhythms in cell proliferation and in the rate of DNA synthesis, which is related to S phase duration. the curve for the circadian rhythm in cell proliferation for asebia epidermis was suppressed and distorted in comparison to that for BALB/cJ epidermis and in comparison to a composite curve produced by averaging the results from ten other published studies.
Effect of Urogastrone On Intestinal Regeneration Is Dose‐Dependent
Authors: Thompson J. S. , Saxena S. K. , Sharp J. G. 
Published: May 2008

ABSTRACTUrogastrone (UG) increases the rate of intestinal regeneration in intestinal defects patched with adjacent serosal surfaces by increasing the rate of epithelial cell migration and proliferation. It also inhibits contraction of the patched intestinal defect. the purpose of this study was to determine the effect of the dose of UG on these processes. Twenty male New Zealand white rabbits (1.9–2.9 kg) had 2 × 5 cm ileal defects patched with adjacent caecal serosal surface. Group I (n=6) served as the control group. Group II (n=5), Group III (n=5) and Group IV (n=4) received UG 0.15, 1.5 and 4.5 μg/kg/h i.v. via mini‐osmotic pumps. Seven days after patching, both epithelialization of the patched defect and neomucosal surface area were significantly increased by UG and the increases were dose‐dependent. Contraction was not inhibited by the lowest dose of UG but was diminished by 1.5 μg/kg/h. Proliferative activity in both neomucosa and adjacent normal mucosa were increased in UG‐treated animals with the greatest increase in rabbits receiving 1.5 and 4.5 μg/kg/h UG. the effect of UG on both epithelialization and contraction of patched intestinal defects is dose‐dependent. Since the lowest dose of urogastrone increased epithelialization without increasing proliferative activity, stimulated cell migration appears to be the earliest effect of UG.
Persistent Dose‐Dependent Increases In Cycling of Haemopoietic Precursor Cells After Irradiation
Authors: Tejero C. , Hendry J. H. , Testa N. G. 
Published: May 2008

ABSTRACTBetween 3 weeks and 36 months after irradiation of mice, there was a dose‐dependent increased level of cycling in haemopoietic stem cells (CFU‐S) and in granulocyte‐macrophage precursor cells (GM‐CFC). For CFU‐S the percentage kill measured using the thymidine suicide technique increased from about 10% in controls to a high and persistent average level of about 45% after 10 Gy γ‐rays, and for GM‐CFC the increase was from about 30% to about 50%.
The maintenance of colchicine‐arrested metaphases in plants requires protein synthesis
Authors: Sans J. , Utrilla L. , De la Torre C. 
Published: May 2008

Abstract With the aim of finding out factors involved in chromosomal condensation, the kinetics of both metaphase accumulation and the subsequent formation of restitution nuclei in the presence of 1 mM colchicine have been analysed in Allium cepa L. meristems. Restitution nuclei are formed by decondensation of the chromosomes from the c‐mitoses and the reformation of nuclear envelopes around them. The study has been carried out in control conditions as well as in conditions which either inhibit protein synthesis (1 μg/ml cycloheximide) or modify the accuracy of transcription (by near ultraviolet light irradiation under anoxia of cells with bromosubstituted‐DNA).The results suggest that the high condensation of chromosomes observed in colchicine‐arrrested metaphases depends on sustained synthesis of protein, and that the DNA regions coding for such proteins are transcribed not before late prophase.By using cells, the genome of which has been partially bromosubstituted, fed bromodeoxyuridine during different fractions of this S period, it could be inferred that the coding regions for the proteins involved in chromosome condensation are probably multiple since they replicate throughout the whole S period.
Double labelling of tissue combining tritiated thymidine autoradiography with immunodetection of bromodeoxyuridine: the autoradiographic significance of inhibition of thymidine incorporation into DNA by bromodeoxyuridine given simultaneously
Authors: Hume W. J. , Thompson J. 
Published: May 2008

Abstract We describe a reproducible method for combining tritiated thymidine ([3H]TdR) autoradiography with immunoperoxidase detection of bromodeoxyuridine (BrdU) in paraffin‐embedded tissues. The technique has been used to examine, in mouse tongue epithelium, the inhibition of incorporation into DNA of [3H]TdR by a simultaneous injection of BrdU in the doses that both compounds are likely to be used in cell proliferation studies. The significance that this inhibition has on prolongation of autoradiograph exposure times, to ensure that all cells that incorporate [3H]TdR are scored as positive, in particular the most lightly labelled cells, has been quantified.The inhibition of uptake into DNA of [3H]TdR from 0.23 to 1.85 MBq (6.25 to 50 μCi) per animal, produced by a simultaneous injection of 2.5 mg BrdU shows a linear, dose‐dependent relationship. Provided the injected dose (in μCi per animal) multiplied by the autoradiographic exposure time (in days) is greater than a value of 700, then all cells that are labelled after incorporation of [3H]TdR alone are also labelled after simultaneous double labelling, despite the latter producing a lower average grain count.
Caffeine increases sensitivity of DNA to denaturation in chromatin of L1210 cells
Authors: Kunicka J. E. , Myc A. , Melamed M. R. , Darzynkiewicz Z. 
Published: May 2008

Abstract.Exposure of exponentially growing L1210 cells to 5 mM and higher concentrations of caffeine perturbs their progression through the cell cycle and results in increased sensitivity of DNA in situ to denaturation. The latter is detected by the increased metachromatic stainability of DNA with acridine orange (AO) and sensitivity to S1 nuclease, measured by flow cytometry. Decreased DNA stability is generally characteristic of chromatin condensation and in untreated cells is observed in mitosis or quiescence (G0). The caffeine‐induced decrease in DNA stability affects the interphase cells regardless of their position in the cycle and the changes are stochastic, concentration‐ and time‐dependent. Populations of cells responding to caffeine are very heterogenous with respect to the degree of destabilization of DNA; sensitivity of DNA to denaturation of the maximally affected cells is similar to that of untreated cells in mitosis. The present method allows one to quantitatively express effects of caffeine on nuclear chromatin in individual cells of large cell populations and may be employed in studies correlating chromatin changes induced by this agent with its effects in modulation of cell sensitivity to radiation or antitumour drugs.
Alteration of cell surface carbohydrates associated with ordered and disordered proliferation of oral epithelia: a lectin histochemical study in oral leukoplakias, papillomas and carcinomas
Authors: Vigneswaran N. , Peters K.‐P. , Hornstein O. P. , Diepgen T. L. 
Published: May 2008

Abstract. Cell surface carbohydrates in healthy oral mucosa (n = 15), leukoplakias without (n= 48) and with (n = 62) dysplasia, oral papillomas (n= 6) and squamous cell carcinomas (SCCs) (n – 40) were examined using the lectins peanut agglutinin (PNA), Ulex europaeus agglutinin I (UEA I), soybean agglutinin (SBA), Helix pomatia agglutinin (HPA), and Griffonia simplicifolia agglutinin I (GS I‐B4). Binding of these lectins in formalin‐fixed, paraffin‐embedded tissues was demonstrated using either the peroxidase‐anti‐peroxidase (PAP) method or the avidin‐biotin method. Healthy oral epithelia revealed binding sites for these lectins mostly in the suprabasal keratinocytes with occasional PNA binding also in their basal cells. Unlike healthy mucosa, a number of leukoplakias without and with dysplasia revealed receptor sites for UEA I also in their basal layer. Only those keratinocytes undergoing squamoidal differentiation exhibited SBA binding. Staining patterns of UEA I and SBA did not vary significantly between either leukoplakias without and with dysplasia or papillomas and SCCs. Conversely, a reduction or lack of binding sites for PNA (Galβl‐3GalNAc), HPA (D‐GalNAcα) and GS I‐B4 (αD‐Gal) was observed more frequently in leukoplakias with dysplasia and SCCs contrasting their counterparts lacking epithelial dysplasia.Cell surface glycosyl residues play an important role in the regulation of cell proliferation and epithelial growth. Aberrant glycosylation in oral dysplastic leukoplakias and carcinomas leading to the lack of the relevant terminal sugar residues from their cell surface carbohydrates is probably a major reason for the hyper‐/ disordered proliferation.
Symmetric and asymmetric cell division in rat corneal epithelium
Authors: Lamprecht J. 
Published: May 2008

Abstract. Mitotic cells in normal, mature rat corneal epithelium were examined with a light microscope on serial, semi‐thick plastic sections.Classification of mitotic figures into horizontally, obliquely or vertically positioned with reference to the epithelial basal lamina has shown that no single configuration predominates. A striking correlation between the position of the daughter cells after cytokinesis and their morphology has been observed. Horizontal cytokinetic pairs were morphologically symmetric but vertical ones were asymmetric, displaying distinct differences between daughter cells. Analysis of earlier mitotic phases has shown that the asymmetry could also be observed in vertical anaphases and telophases.The data provide clear morphological evidence for real asymmetric (unequal) cell division in a replacing epithelium in an adult mammal. It is concluded that asymmetric cell division in the corneal epithelium coexists with, and is as frequent as symmetric (equal) cell division. Randomness of mitotic spindle positioning implies that diverse forms of cell transfer from the proliferative into the differentiative epithelial compartments must operate. Therefore, the universality of the general model of cell renewal in stratified epithelia, which assumes a strong predominance of horizontal mitoses, exclusively equal mitotic divisions and one form of cell transfer, is questioned.
Proliferative changes in the genital tissue of female mice during the oestrous cycle
Authors: Evans G. S. , Gibson D. F. C. , Roberts S. A. , Hind T. M. , Potten C. S. 
Published: May 2008

Abstract. Changes in proliferation and number of epithelial cells of the murine genital tract, during the oestrous cycle, have been studied. A total of 47 animals in the pro‐oestrous, metoestrous and dioestrous phases of the cycle were staged retrospectively on the basis of the genital tract histology. The average duration of the oestrous cycle in these aninals was 4 days, and half of this period was occupied by the pro‐oestrous/oestrous phases. Significant cycles of growth were observed in the luminal uterine epithelium and in the basal epithelium of the cervix‐vagina. Most of this growth occurred during the pro‐oestrous phase, which lasted approximately 1 day. During this time the numbers of luminal epithelial cells in the uterus and suprabasal cells in the cervix‐vagina increased 2–3 fold. This pattern of growth appeared partly synchronous and corresponded to the period when serum oestrogen levels are at their highest.A corresponding and rapid reduction in the numbers of uterine luminal epithelial cells and suprabasal cells in the cervix and vagina was noted during the early metoestrous phase; and this occured during the period when serum oestrogens are at their lowest levels. No significant periodicity in the proliferation and numbers of the uterine gland epithelial cells was noted during the cycle. The kinetic role and function of the gland cells is discussed in relation to these data.
The G1 interval in the mammalian cell cycle: dual control by mass accumulation and stage‐specific activities
Authors: Murray L. E. , Singer R. A. , Fenwick R. G. , Johnston G. C. 
Published: May 2008

Abstract. The temporal determinants of the G1 cell cycle interval were investigated using nine mammalian cell lines. In each case, cells were allowed to proliferate for many cell cycles under conditions that slowed progress through S phase without an equivalent impairment of overall mass accumulation. This disproportionate inhibition of progress through the cell cycle caused newly produced cells to be more massive than usual. Under these growth conditions, the determinants of the length of the G1 interval became evident.For two cell lines, HeLa S3 and NIH 3T3, a protracted S phase, and the resultant increase in mass, resulted in a dramatically shortened G1 interval. Thus, for these cell lines, a major portion of G1 time exists to accommodate mass accumulation needed to initiate the subsequent S phase. Nevertheless, under conditions that protracted S phase and shortened the G1 interval, cells still exhibited a measurable G1 time, reflecting the stage‐specific activities within G1. One activity that may be responsible for this obligatory G1 time is the synthesis of a labile protein.For other cells studied here, protraction of S phase also caused proliferating cells to become more massive, but in these cases there was no diminution of the G1 time. For these cells, the entire G1 interval must accommodate G1‐specific activities necessary to initiate a new cell cycle.A unifying view of the G1 interval recognizes the two distinct influences that determine the time spent in G1: the need to accumulate sufficient mass to initiate a new DNA‐division sequence; and the stage‐specific events necessary for the subsequent S phase. The length of the G1 interval is dictated by the longer of these two time‐consuming activities.
Cell cycle related studies on thymidine kinase and its isoenzymes in Ehrlich ascites tumours
Authors: He Q. , Skog S. , Tribukait B. 
Published: May 2008

Abstract. Thymidine kinase (TK) activity was measured in relation to the cell cycle of in vivo growing ascites tumour cells. The cells were synchronized by means of centrifugal eiutriation and the cell cycle composition of the cell fractions was determined by flow cytometry. TK activity was low in GI, increased during S phase and declined in G2. A half‐life of TK activity of about 45 min was found throughout the cell cycle.Four isoenzymes at PI values of 4.1, 5.3, 6.9 and 8.3, denoted as isoenzymes 1–4, were identified using isoelectric focusing. Isoenzymes 3 and 4 were responsible for the profound cell cycle related changes in the TK activity. Corresponding isoenzymes were also found in the fetal mouse liver. In the adult mouse liver isoenzyme 2 was the dominating isoenzyme. The half‐life of the isoenzymes was in the same range as for the total TK activity.We conclude that the low TK activity in G1 is due to degradation of the enzyme in G2 at a normal rate combined with an arrest in the synthesis of TK. We also conclude that isoenzyme 4 and the intermediate isoenzyme 3, which had earlier been suggested to be a mitochondrial form of TK, in fact represent cytoplasmatic forms of TK. According to cell cycle and PI studies, isoenzyme 2 belongs to the mitochondrial form. Studies with various phosphor donors and specific substrates, however, indicate that it also contains a cytoplasmic component.
Application of a DNA double labelling method for the flow cytometric analysis of recruitment of non‐cycling cells in a mixed population of P and Q cells
Authors: Bakker P. J. M. , De Vries R. J. L. , Tukker C. J. , Hoebe R. A. , Barendsen G. W. 
Published: May 2008

Abstract. In this paper we describe the application of a non‐radioactive DNA double labelling and staining method to an analysis of cell proliferation kinetics by flow cytometry, aimed at the direct measurement of recruitment rates in cell cultures. The method is based on the application of two halogenated deoxyuridines: iododeoxyuri‐dine (IdUrd) and chlorodeoxyuridine (CldUrd) which are incorporated into DNA synthesizing cells. By applying two commercially available monoclonal antibodies both deoxyuridines can be detected separately. To measure recruitment all proliferating cells in a plateau phase culture were labelled first with IdUrd applied during a time interval approximately equal to the cell cycle time. Subsequently, recruitment induced by a medium change was analysed by flow cytometric assessment of incorporation of CldUrd in cells which had not taken up IdUrd.Experiments designed to determine the toxicity of continuous labelling with IdUrd in different concentrations and of pulse labelling with CldUrd showed that there was no effect on the progression of cells through the cell cycle. The aim of this study is to test the sensitivity of the procedure to detect changes in proliferation kinetics, in particular the entrance of resting cells into the S phase. Although the cell culture model used is very simple, the results demonstrate clearly that a low rate of recruitment can be detected. It is suggested that the procedure described here is specific and sensitive enough to quantify changes in cell proliferation in tumours induced by various treatments and has advantages over other methods, which measure recruitment indirectly, or directly by using two radioactive thymidines.