bluuebunny/crossref_metadata_2025_split huggingface dataset:
Haemopoietic spleen colony growth: a versatile, parsimonious, predictive model
Authors: Blackett N. M. 
Published: May 2008

Abstract. Substantial support has been obtained for the stochastic model for stem cell differentiation first proposed by Till, McCulloch & Siminovitch (1964), over 20 years ago. By adding a cell maturation pathway, it is possible to predict (by computer simulation) the total number of cells and consequently the time at which individual colonies appear and disappear.Only a few uncontroversial assumptions are required to predict that cells, uniform with respect to self‐renewal, are capable of producing the high proportions of late disappearing and late appearing colonies observed experimentally in the spleens of irradiated mice that have been injected with normal haemopoietic cells. It is shown that differences in stem cell self‐renewal only slightly influence the time of appearance of colonies; whereas changes in the kinetics of the maturing cells, by changing the size of colonies, has a marked effect on the time of appearance and disappearance of colonies and on the average doubling‐time of colony‐forming cells per colony (but not the doubling‐time of individual colonies).These results (1) seriously question the prevailing view that spleen colonies scored at 8 days measure a separate population (without the capacity for self‐renewal), from those scored at 12 days; (2) argue against the existence of multiple sub‐populations of stem cells with differing self‐renewal and toxicity to cytotoxic agents; (3) help to identify those experiments for which it is obligatory to postulate heterogeneity, and (4) are consistent with self‐renewal being regulated by a feedback control of stem cell differentiation, to which only proliferating stem cells can respond and where the stimulus for differentiation decreases at a time when the bone marrow is known to be depleted.
Variability of ecdysteroid‐induced cell cycle alterations in Drosophila Kc sublines
Authors: Besson M. T. , Cordier G. , Quennedey B. , Quennedey A. , Delachambre J. 
Published: May 2008

Abstract. The cell cycle of two lines isolated from Drosophila Kc cells was followed by flow cytofluorometry and cell counting. The first line is the 8‐9K clone which grew in a medium supplemented with 5% serum; the second, named subline Kc0, grew in a serum‐free medium. The stationary phase is characterized by a G2 cell accumulation: 73% in the 8‐9K clone and 50% in the Kc0 subline.When the medium was supplemented with the steroid moulting hormone 20‐hydroxyecdysone, more than 90% of 8‐9K cells and 65% of Kc0 cells were progressively arrested in G2. In the continuous presence of 20‐hydroxyecdysone, most of the 8‐9K cells remain G2‐arrested; no massive G2 release into M was observed and only a few cells were able to divide. When treated for only 3 or 7 days, a transient release into M and proliferation occurred after hormone‐free medium renewal, largely masked by G2 cell death. These results are discussed in comparison with other reports on cell cycle alteration induced by ecdysteroids.
The Spleen Colony Technique. Iii. Comparison of the Overlap Effect and of Errors In Cfu‐S Determination and the [3H]‐Thymidine Suicide Data For Several Strains of Mice
Authors: Znojil V. , Necas E. 
Published: May 2008

ABSTRACTA mathematical model of errors of the spleen colony technique is applied to data obtained from four mouse strains and F1 hybrids. the variance of the colony counts was close to the Poisson distribution in inbred mice and F1 hybrids. However, it should be checked regularly. the magnitude of the error in CFU‐s determination and of the estimations of the S phase fraction was derived, and is presented relative to the mean colony counts for all mouse strains studied. the optimum spleen colony counts are generally higher than those which are commonly used. However, the utilization of the optimum spleen colony counts requires a correction for the effect of colony overlap.
Cytostatic and Cytotoxic Effects of Pannon (P‐30 Protein), A Novel Anticancer Agent
Authors: Darzynkiewicz Z. , Carter S. P. , Mikulski S. M. , Ardelt W. J. , Shogen K. 
Published: May 2008

ABSTRACTP‐30 Protein is a novel protein, of molecular weight approximately 15 kD, obtained from the extract of a vertebrate tissue showing in vivo antitumour activity. Cytostatic and cytotoxic effects of this product in its purified form (P‐30 Protein) or in partially purified extracts (Pannon) were studied in vitro on human leukaemic HL‐60, human submaxillary carcinoma A‐253, human colon adenocarcinoma Colo 320 CM and murine erythroleukaemia (Friend leukaemia) cell lines. of these cells, HL‐60, A‐253 and Colo 320 CM were sensitive and Friend leukaemia resistant to this agent. the effects were time‐ and concentration‐dependent. During the initial 24–48 h of treatment, a slowdown in cell proliferation was apparent but cell death was not extensive. After 24–48 h, there was a reduction in the proportion of cells in S phase of the cell cycle and the cells became preferentially arrested in G1 phase. the G1 cells showed high heterogeneity with respect to RNA content and some cells were characterized by very low RNA content. Progressive cell death occurred in cultures maintained with Pannon for up to 7 d in proportion to its concentration. Reductions of 50 and 90% in clonogenicity of A‐253 cells were observed during their growth in the presence of 0.13 and 1.5 μg/ml of this protein, respectively. Exponentially growing cells were more sensitive to Pannon compared with cells from confluent cultures. Colonies of A‐253 cells growing in the presence of Pannon were much smaller in size compared with control colonies, indicating that the rate of proliferation of clonogens is reduced by this agent. It appears that P‐30 Protein induces cytostatic effects via modulation of cell transition to quiescence or differentiation. the mechanism of its cytotoxic activity is unclear.
A mathematical model of erythropoiesis in mice and rats Part 3: Suppressed erythropoiesis
Authors: Wulff H. , Wichmann H. E. , Pantel K. , Loeffler M. 
Published: May 2008

Abstract A mathematical model of erythropoietic cell production and its regulation process has been proposed in a preceding paper. It is primarily based on the assumption that the number of cell divisions taking place in the CFU‐E and erythropoietic precursor stages can be regulated depending on the oxygen supply to the tissue. Here we provide evidence that this model adequately describes situations of suppressed erythropoiesis. In detail this implies a quantitative description of the following processes: (1) changes in tissue oxygen tension (PtO2) due to increase in red cell numbers (red cell transfusion, posthypoxia), decrease in plasma volume (dehydration) or increase in atmospheric oxygen pressure (hyperoxia), (2) PtO2 dependent reduction of erythropoietin (EPO) production, (3) dose‐response of reduced EPO‐levels on erythropoietic amplification (omission of three to five mitoses).Model simulations are compared to experimental data obtained from red cell transfusion, posthypoxia, hyperoxia and dehydration. A satisfactory agreement suggests that the model adequately describes and correlates different ways to suppress erythropoiesis. It quantifies the role and relative contribution of the haematocrit, haemoglobin concentration, atmospheric oxygen pressure, tissue oxygen pressure and plasma volume as triggers in erythropoietic suppression under various conditions. In conjunction with the preceding two papers it could be shown that one unique set of model parameters is sufficient to describe erythropoiesis in steady state, stimulation and suppression. Limitations of the model are discussed and experiments for a more detailed investigation of the feedback mechanisms are proposed.
Cyclin/PCNA immunostaining as an alternative to tritiated thymidine pulse labelling for marking S phase cells in paraffin sections from animal and human tissues
Authors: Galand P. , Degraef C. 
Published: May 2008

Abstract Paraffin sections from animal or human tissues fixed in different fixatives were submitted to immunostaining with the mouse monoclonal antibody 19A2, developed by Ogata et al. (1987a) against cyclin/PCNA. Detection of the bound antibody was performed by the indirect method with biotinylated sheep antibody and streptavidin‐biotin‐peroxidase complexes. No, or faint, nuclear staining was seen in material fixed in ethanol, Bouin, Bouin‐Hollande, Carnoy or formaldehyde, whereas readily detectable immunocytochemical reaction was constantly observed over nuclei of methanol‐fixed tissues. Hydrolysis with 2 N HCl prior to immunocytochemistry (as currently performed to render incorporated BrdU accessible to antibodies) somewhat improved the results with Bouin or Carnoy and markedly augmented the intensity of the peroxidase reactions in formaldehyde and in methanol‐fixed tissues.The distribution of the positive nuclei in the two latter cases coincided with the proliferative compartment. On the other hand, double labelling with [3H]‐thymidine and with the cyclin/PCNA antibody revealed that in methanol‐fixed tissues the cyclin/PCNA labelling index did not differ by more than 6% from the [3H]‐thymidine index. Besides the two labels overlapped in a proportion of labelled cells that was in reasonable agreement with expectation considering cells flow in and out of S phase since the time of [3H]‐thymidine injection. This indicates that both labels recognize the same cells in this material. In contrast, in formaldehyde‐fixed tissues, the cyclin/PCNA labelling index markedly exceeded the [3H]‐thymidine labelling index. From this it is concluded that cyclin/PCNA immunostaining can be used:

In formaldehyde‐fixed tissues (including existing material stored as paraffin blocks): for defining and mapping the proliferative (or germinative) compartment.
In methanol‐fixed tissues as a substitute to the [3H]‐thymidine autoradiographic labelling index.

From this, a method is proposed (derived from classical ‘double‐labelling’technique) for measuring S phase duration in tissues fixed at a known interval time after a single labelling with [3H]‐thymidine (or BrdU) and submitted to cyclin/PCNA immunocytochemical detection and to autoradiography (or to BrdU immunostaining).
Circadian synchronization of liver regeneration in adult rats: the role played by adrenal hormones
Authors: Barbason H. , Bouzahzah B. , Herens Ch. , Marchandise J. , Sulon J. , Cantfort J. van 
Published: May 2008

Abstract The role played by the adrenal hormones in the regulation of liver proliferation in adult rats was investigated under various experimental conditions.In untreated control groups, cell growth was very low and endogenous corticosterone levels showed a clearly‐defined circadian rhythm with a peak in the evening. Adrenalectomy depressed the level of endogenous corticosterone immediately and the growth rate of the liver increased significantly. We were able to prevent this effect by repeated injections of corticosterone at physiological doses.After a 1/3 hepatectomy and a sham‐operation, the corticosterone blood level maintained its normal circadian pattern with the exception of a transient increase during the first two post‐operative hours. After a hepatectomy of this kind, a negative correlation was found to exist between the adrenal hormone level and the waves of DNA synthesis; the subsequent mitoses appeared in two successive circadian waves of decreasing amplitude, a maximum value being reached in the morning. In rats submitted to a 1/3 hepatectomy and an adrenalectomy simultaneously, the endogenous corticosterone level fell significantly after a post‐operative peak. The regenerating pattern was completely different from that induced by 1/3 hepatectomy alone. The rise in the labelling index began earlier and rose to significantly higher values; it was then followed by a single large mitotic wave without any circadian rhythm.These results favour the hypothesis that adrenal hormones have a significant effect on the negative control of liver regeneration. Circadian changes in the corticosterone level were responsible for the nycthemeral pattern observed in the regenerating liver after a partial hepatectomy. The results show a marked inhibition of the G1‐S transition, particularly in the evening, when the endogenous corticosterone concentration was at its highest. Also discussed is the relationship between corticoids and ‘chalones’, which synergetically inhibit the passage from G0 into the cell cycle.
Mathematical model analysis of mouse epidermal cell kinetics measured by bivariate DNA/anti‐bromodeoxyuridine flow cytometry and continuous [3H]‐thymidine labelling
Authors: Aarnæs E. , Kirkhus B. , Clausen O. P. F. 
Published: May 2008

Abstract. In a previous study the epidermal cell kinetics of hairless mice were investigated with bivariate DNA/anti‐bromodeoxyuridine (BrdU) flow cytometry of isolated basal cells after BrdU pulse labelling. The results confirmed our previous observations of two kinetically distinct sub‐populations in the G2 phase. However, the results also showed that almost all BrdU‐positive cells had left S phase 6–12 h after pulse labelling, contradicting our previous assumption of a distinct, slowly cycling, major sub‐population in S phase. The latter study was based on an experiment combining continuous tritiated thymidine ([3H]TdR) labelling and cell sorting. The purpose of the present study was to use a mathematical model to analyse epidermal cell kinetics by simulating bivariate DNA/BrdU data in order to get more details about the kinetic organization and cell cycle parameter values. We also wanted to re‐evaluate our assumption of slowly cycling cells in S phase.The mathematical model shows a good fit to the experimental BrdU data initiated either at 08.00 hours or 20.00 hours. Simultaneously, it was also possible to obtain a good fit to our previous continuous labelling data without including a sub‐population of slowly cycling cells in S phase. This was achieved by improving the way in which the continuous [3H]TdR labelling was simulated. The presence of two distinct sub‐populations in G2 phase was confirmed and a similar kinetic organization with rapidly and slowly cycling cells in G1 phase is suggested. The sizes of the slowly cycling fractions in G1 and G2 showed the same distinct circadian dependency. The model analysis indicates that a small fraction of BrdU labelled cells (3–5%) was arrested in G2 phase due to BrdU toxicity. This is insignificant compared with the total number of labelled cells and has a negligible effect on the average cell cycle data. However, it comprises 1/3 to 1/2 of the BrdU positive G2 cells after the pulse labelled cells have been distributed among the cell cycle compartments.
The effects of the platinum anti‐tumour agents on renal cell kinetics and the response to a second cytotoxic agent
Authors: Ewen C. , Hendry J. H. 
Published: May 2008

Abstract. Following 15 mg kg‐1 cisplatin to mice, the labelling index (LI) in the kidney decreased from 0–4% to & lt;0–01% at 1–3 d, increased to 1–9% at day 16 and returned to control levels by day 30. Cytotoxicity was assessed by counts of viable tubule cross‐sections and recovery was incomplete up to 14 months after treatment.Cisplatin treatment impaired the regeneration response to a dose of 16 mg kg‐1 uranyl nitrate (UN) given 14 d after cisplatin when assessed by an increase in LI and sub‐capsular tubule count. However, there was recovery with greater time intervals. At nine months after cisplatin there was no difference in response to UN of controls and mice previously treated by cisplatin.Prior treatment with paraplatin or iproplatin at LD50 doses produced not only no histopathological changes but also no impairment of the subsequent responses to UN.
The type, origin and function of the odontogenic cells of continuously growing guinea‐pig molars
Authors: Nataatmadja M. I. , Orams H. J. , Reade P. C. 
Published: May 2008

Abstract. Little is known about which cell types act as the origin of odontogenic stem cells and how these stem cells differentiate to become functional. In the present study 3‐day‐old guinea‐pigs were injected with tritiated thymidine, killed at intervals and their molars studied. The odontogenic cells were found to originate from the stem cells which by autoradiography were shown to be slow cycling and lightly labelled. As they differentiated they became heavily labelled and were designated transit ‘dividing cells’. With further differentiation the cells were unlabelled and were designated ‘simple transit cells’.It was concluded from the present study that outer enamel epithelium functioned as the source of all odontogenic epithelium; that primitive mesenchyme around the cervical loop functioned as the source of all odontogenic mesenchyme and that all of the transit cells which differentiated to become functional migrated coronally.
Proliferation kinetics and PCNA expression of HL‐60 cells following ionizing irradiation and granulocytic differentiation
Authors: Sendler A. , Kaffenberger W. , Nuyken I. , Van Beuningen D. 
Published: May 2008

AbstractThe human promyelocytic leukaemia cell line, HL‐60, was investigated with regard to proliferation and terminal differentiation following irradiation. The cells were X‐irradiated and induced with 1.25% dimethyl sulfoxide (DMSO) towards the granulocytic lineage. Proliferation was measured via cell growth, clonogenicity and the bromodeoxyuridine/DNA incorporation assay. Immunohistochemical detection of proliferating cell nuclear antigen (PCNA) expression was used to discriminate cycling from non‐cycling cells. The differentiation obtained was proved by testing for the immune function of the respiratory burst (NBT reduction test). The HL‐60 cells studied revealed a high radiosensitivity (D0= 0.63 Gy). After induction with DMSO, declines in cell growth, clonogenicity and PCNA positivity of the cells indicated a decrease in proliferation and an increase in differentiation. Starting on day 2 in culture, irradiation after seeding with 1 Gy accelerated the loss of the PCNA expression in induced cells (46%v. 3% PCNA‐negative control cells on day 3). Induced cells gained the capability of exerting the respiratory burst, which was found to be dose‐dependent radiosensitive (42% and 12% NBT‐positive cells after 1 and 2 Gy, respectively, v. 53% NBT‐positive control cells on day 8). Subpopulations in the cell line were evident in all parameters investigated. We discuss the HL‐60 cell, not only as a model comparable to human progenitor cells, but also as a suitable tool in radiobiological research with regard to proliferation and differentiation following ionizing irradiation.
Cell proliferation kinetics of normal and tumour tissue in vitro: quiescent reproductive cells and the cycling reproductive fraction
Authors: Baker F. L. , Sanger L. J. , Rodgers R. W. , Jabboury K. , Mangini O. R. 
Published: May 2008

AbstractCurrent methods for measuring the cell kinetics of human tumours are made and interpreted within the context of a simplistic two compartment model for cell proliferation, consisting of cells that are cycling and those that are not. It is now recognized that the non‐cycling compartment of many tumours is heterogeneous, composed of non‐reproductive end‐stage cells and reproductive cells that are dormant/quiescent. We have developed an in vitro analysis that distinguishes for the first time quiescent reproductive cells from non‐reproductive end‐stage cells and have integrated this analysis with monolayer clonogenic and suicide assays to simultaneously quantitate the duration of the cell cycle and reproductive cells that are: cycling, quiescent, clonogenic, and non‐reproductive end‐stage cells. We have defined a new parameter, the Cycling Reproductive Fraction (CRF), which is the cycling cell population referenced specifically to the reproductive cell population. Measurements of CRF from 72 tumour biopsies and from 5 normal foreskins showed that CRF approached 100% in some tumours; however, CRF showed near normal values (< 1%) in others suggesting that cell cycle control may be maintained in some tumours. Because of CRF's improved specificity, we believe that CRF may enhance classification, prognostication, and the optimization and prediction of response to chemotherapy.
Existence of a commitment program for mitosis in early G1 in tumour cells
Authors: Larsson O. , Zetterberg A. 
Published: May 2008

AbstractThe proliferation of normal non‐tumourigenic mouse fibroblasts is stringently controlled by regulatory mechanisms located in the postmitotic stage of G1 (which we have designated G1 pm). Upon exposure to growth factor depletion or a lowered de novo protein synthesis, the normal cells leave the cell cycle from G1 pm and enter G0. The G1 pm phase is characterized by a remarkably constant length (the duration of which is 3 h in Swiss 3T3 cells), whereas the intercellular variability of intermitotic time is mainly ascribable to late G1 or pre S phase (G1 ps) (Zetterberg & Larsson (1985) Proc. Natl. Acad. Sci. USA82, 5365). As shown in the present study two tumour‐transformed derivatives of mouse fibroblasts, i.e. BPA31 and SVA31, did not respond at all, or only responded partially, respectively, to serum depletion and inhibition of protein synthesis. If the tumour cells instead were subjected to 25‐hydroxycholesterol (an inhibitor of 3‐hydroxy‐3 methyglutaryl coenzyme A reductase activity), their growth was blocked as measured by growth curves and [3H]‐thymidine uptake. Time‐lapse analysis revealed that the cells were blocked specifically in early G1 (3‐4h after mitosis), and DNA cytometry confirmed that the arrested cells contained a G1 amount of DNA. Closer kinetic analysis revealed that the duration of the postmitotic phase containing cells responsive to 25‐hydroxycholesterol was constant. These data suggest that transformed 3T3 cells also contain a ‘G1 pm program’, which has to be completed before commitment to mitosis. By repeating the experiments on a large number of tumour‐transformed cells, including human carcinoma cells and glioma cells, it was demonstrated that all of them possessed a G1 pm‐like stage. Our conclusion is that G1 pm is a general phenomenon in mammalian cells, independent of whether the cells are normal or neoplastic.
Effects of omeprazole on cell kinetics of carcinogen‐induced colon tumours in rats
Authors: Hurwitz A. , Sztern M. I. , Looney G. A. , Pinson D. M. , Bauer K. D. , Kimler B. F. 
Published: May 2008

AbstractThis study was designed to evaluate the effects of hypergastrinaemia induced via suppression of gastric acid by omeprazole on carcinogen‐induced colon cancer in rats. The carcinogen methylazoxymethanol (MAM), 30 mg/kg, was administered intraperitoneally at 6‐weekly intervals to Sprague‐Dawley rats. Four weeks after the last MAM injection, the first daily dose of omeprazole, 40 mg/kg, was given by gastric gavage to one group of rats, and the rest were given buffered methylcellulose vehicle. After 10 weeks of daily omeprazole or vehicle, the rats were anaesthetized with ether, blood samples obtained, and animals sacrificed. Gastrin levels in serum from omeprazole‐treated rats were elevated nearly six‐fold. DNA and RNA levels in gastric mucosa were unchanged by omeprazole, but protein content was somewhat reduced. No biochemical or histological changes related to omeprazole treatment were observed in normal colon. The number of tumours, tumour volumes, and total tumour burden were not significantly different in colons of vehicle‐ or omeprazole‐treated rats. Analysis by flow cytometry revealed that the S phase fraction was lower in tumour cells from omeprazole‐treated animals; and that the frequency of DNA aneuploidy was also reduced. The results indicate that while omeprazole‐induced suppression of stomach acid in rats elevates levels of gastrin in serum, it does not substantially alter the biochemical or cellular characteristics of carcinogen‐induced colon tumours.