bluuebunny/crossref_metadata_2025_split huggingface dataset:
The measurement of villus cell population size in the mouse small intestine in normal and abnormal states: a comparison of absolute measurements with morphometric estimators in sectioned immersion‐fixed material
Authors: Wright N. A. , Carter J. , Irwin M. 
Published: May 2008

Abstract From a functional viewpoint, the most important part of the small intestinal mucosa is the villus epithelium; in the experimental study of intestinal adaptation it is often necessary to estimate the size of the population. For these reasons, a systematic study of methods of measuring the size of the villus cell population was undertaken in villi of normal morphology from control animals, and in villi of abnormal morphology as produced by treatment of mice with cytosine arabinoside (Ara‐C).The villus cell population can be measured with precision and accuracy in both normal and abnormal mucosal states, with a relative standard error usually less than 5%, with good reproducibility, and with very low counting errors. In the mouse a practically linear relationship between the villus cell population size and position in the small intestine can be shown. In normal, control animals, linear estimates of villus population, for example the villus height, the villus core height, and the villus row count measured in sections of immersion‐fixed material, were found to be rough approximations as indicators of the villus cell population, and were highly correlated with it. Product variables, comprising the products of a height with a width measurement, show a large improvement over the linear variables as estimators of villus cell population. In populations of abnormally shaped villi produced by Ara‐C, both linear and product variables showed a considerable decrease in correlation with the villus cell population. Consequently, indirect, linear measurements of the villus population size do not accurately reflect the size of the villus population in abnormal villi.Finally, a method comparing theoretical and measured surface: volume indices was used to indicate that the most appropriate shape for normal mouse villi is a simple cylinder; this method would also be applicable for other villus cell populations.
Probability of self‐renewing divisions of spermatogonial stem cells in colonies, formed after fission neutron irradiation
Authors: van Beek M. E. A. B. , Meistrich M. L. , de Rooij D. G. 
Published: May 2008

Abstract.Repopulating spermatogenic colonies, found in the seminiferous epithelium after irradiation with fast‐fission neutrons, were studied to determine the cha nce that a stem cellAsingle (As spermatogonium would complete a self‐renewing division (P). Mathematical formulas originally derived for such studies in haemopoietic colonies were employed, and a method specifically aimed at spermatogenic colonies was developed. The results showed that during the first division after irradiation, P is close to 1 ‐0. P decreases in later generations, but remains 0‐7 or higher up to the 4th or 5th divisions. The mean value for P was over 0‐8, which is higher than the value of 0‐6‐0‐7 found for stem cells in haemopoietic colonies.
In vivo regulation of granulocyte protluction in acute inflammation
Authors: Hamood M. , Fondu P. 
Published: May 2008

Abstract. In order to study in vivo the enhanced granulopoiesis that occurs during acute inflammation, 1–3 sterile metallic copper rods were inserted subcutaneously into mice either at the same place (one abscess) or at different sites (multiple abscesses). Diffusion chambers filled with bone marrow cells were implanted intraperitoneally for 3 days. When a single abscess was created, the granulocytic content of the diffusion chamber increased similarly whatever the number of inserted copper rods. However, there was a direct relationship between the number of abscesses and the number of granulocytic cells harvested from the diffusion chambers.In order to investigate the role of T‐lymphocytes in the production of diffusible stimulating factors that act on diffusion chamber granulopoiesis, cyclosporin A (CyA) was given to the mice with implanted copper rods. CyA abrogated the induced enhancement of CFU‐S, CFU‐GM and mature granulocyte numbers inside the diffusion chamber. The stimulatory effect of inflammation on diffusion chamber granulopoiesis was not observed in T‐lymphocyte‐deficient nude mice.These data suggest that in vivo stimulation of granulopoiesis is related to the level of inflammation, and that this effect requires the functional integrity of T‐lymphocytes.
Importance of cell cycle perturbations on the effectiveness of N‐methylformamide and anti‐neoplastic drugs in combination
Authors: Cucco C. , D'Agnano I. , Marangolo M. , Candiloro A. , Zupi G. 
Published: May 2008

Abstract. The effect of N‐methylformamide (NMF) in combination with Adriamycin (ADM) and cis‐diamminedichloroplatinum (DDP) on the cell survival and cell cycle kinetics of two human tumour lines was assessed: HT29 colon carcinoma and M14 melanoma cells were exposed to ADM and DDP alone or in combination with a non‐cytotoxic dose of NMF, according to different schedules.The results demonstrate that NMF exposure sensitized both tumour cell lines to the lethal activity of ADM and DDP; however, reverse sequences had to be applied to reach an increase in the lethal activity of the two different drugs.The ADM‐NMF combination determined a powerful decrease in the surviving fraction of the two cell lines when ADM was given as the first agent (ADM → NMF), while the reverse sequence did not increase the ADM cytotoxic effect. With respect to the DDP‐NMF association, the sequence which accounted for a greater sensitizing effect was NMF administration followed by DDP treatment (NMF → DDP).This work demonstrates the importance of timing in combined treatments which involve NMF. A delay in cell proliferation elicited by NMF exposure could be responsible for the effectiveness of the combined treatment.
Measurement of cell proliferation by enzyme‐linked immunosorbent assay (ELISA) using a monoclonal antibody to bromodeoxyuridine
Authors: Perros P. , Weightman D. R. 
Published: May 2008

Abstract. An ELISA was developed and optimized to measure cell proliferation using a monoclonal antibody to bromodeoxyuridine (BrdUrd).Incorporation of BrdUrd into myoblast monolayers, measured as the optical density at 492 nm, increased in response to fetal calf serum, IGF‐I and EGF, the ELISA data correlated closely with data obtained by BrdUrd immunocytochemistry (r = 0·984), cell counting (r = 0·972) and tritiated thymidine uptake by liquid scintillation counting (r = 0·990).The BrdUrd ELISA is a useful alternative to measurement of tritiated thymidine uptake by scintillation counting, and has the added advantages of dispensing with the use of radioactivity and of being less labour intensive.
A model of the control of cellular regeneration in the intestinal crypt after perturbation based solely on local stem cell regulation
Authors: Paulus U. , Potten C. S. , Loeffler M. 
Published: May 2008

Abstract. The control mechanisms involved in regeneration of murine intestinal crypts after perturbations are presently not well understood. The existence of some feedback signals from the cells on the villus to the cells in the crypt has been suggested. However, some recent experimental data point to the fact that regeneration in the crypt starts very early after perturbation, at a time when the villus cell population has hardly changed. In particular, this early cell proliferative activity is seen specifically at the bottom of the crypt, i.e. in the presumed stem cell zone and furthest from the villus.The objective of this study was to investigate whether a new concept of regulation operating solely at the stem cell level could explain the present mass of accumulated data on the post‐irradiation recovery, which is an extensively studied perturbation from the experimental point of view. In order to check its validity, the new concept was formalized as a mathematical simulation model thus enabling comparison with experimental data. The model describes the cellular development from stem cells to the mature villus cells. As a basic feature it is assumed that the self‐maintenance and the cell cycle activity of the stem cells are controlled by the number of these cells in an autoregulatory fashion. The essential features of the experimental data (i.e. the recovery with time and the consistency between different types of measurements) can be very well reproduced by simulations using a range of model parameters. Thus, we conclude that stem cell autoregulation is a valid concept which could replace the villus crypt feedback concept in explaining the early changes after irradiation when the damage primarily affects the crypt. The question of the detailed nature of the control process requires further investigation.
Hydroxyurea exposure alters mouse testicular kinetics and sperm chromatin structure
Authors: Evenson D. P. , Jost L. K. 
Published: May 2008

Abstract. The effects of hydroxyurea (HU) on testicular cell kinetics and sperm chromatin differentiation were investigated in mice. Whole testis, minced testicular cell suspensions and caudal epididymal sperm cells were obtained at 8 and 29 days after i.p. injections containing 0, 25, 50, 100, 200, 400 and 500 mg/kg HU X 5 days. Testis weights were unaffected by 25 mg/kg HU while 500 mg/kg caused up to a 50% loss of testicular weight by 29 days. Flow cytometrically measured acridine‐orange (AO) stained testicular cells revealed altered population ratios at the highest dosages at 8 days and for all dosages except 25 mg/kg HU at 29 days. At 8 days, 400–500 mg/kg HU caused a near depletion of tetraploid cells. Flow cytometry of AO stained sperm, previously treated with acid to potentially induce DNA denaturation, was used to follow the shift from normal chromatin structure to an abnormal form with increased sensitivity to DNA denaturation in situ. The extent of DNA denaturation was quantitated for each cell by the computer‐derived value alpha t, αt= [red/(red+green) fluorescence]. The flow cytometry measures, standard deviation of αt (SDαt), mean of αt (Xαt) and cells outside the main peak of αt (COMPαt), gave similar dose response curves to the sperm head morphology assay. SDαt was more sensitive than the Xαt as a measure of HU‐induced alteration of chromatin structure.The major conclusions reached are that HU inhibits DNA synthesis, probably by inhibiting ribonucleotide reductase, causing maturation depletion of pachytene spermatocytes and, subsequently, depletion of meiotic daughter cells and differentiated cell types leading to mature sperm. This inhibition of DNA synthesis is related to an alteration of sperm chromatin structure and abnormal sperm head morphology.
Comparison of isotopic and immunohistochemical methods of studying epithelial cell proliferation in hamster tongue
Authors: Warnakulasuriya K. A. A. S. , Johnson N. W. 
Published: May 2008

AbstractOur purpose was to validate different approaches to the study of cell proliferation in stratified squamous epithelia, using oral mucosa as a model. Dorsal and ventral tongue from the hamster were examined following in vivo labelling with tritiated thymidine and bromodeoxyuridine (BrdUrd), and in vitro labelling with BrdUrd. These were compared with direct immunolabelling of fixed tissue sections with monoclonal antibody PC10. For the former methods S phase cells were quantified following autoradiography or immunohistochemistry. We conclude that the proliferative status of simple, flat, lining mucosae such as ventral tongue can be derived by all three prelabelling methods and, on average, 18–19 cells per surface millimetre length were in DNA synthesis. On the other hand dorsal tongue epithelium, which is thicker, has an undulating morphology and a complex cell renewal pattern, gives different results with the three labelling methods. In both sites the proliferating cell nuclear antigen (PCNA) index was fourfold that obtained by nucleotide labelling. This is consistent with PCNA marking proliferative cells in other phases of the cell cycle in addition to the S phase. Thus, there are potential differences between the information on proliferative status derived by PCNA immunohistochemistry and other established cell cycle markers, which need to be taken into account in the interpretation of epithelial cell kinetic data in health and disease.
Binucleation and polyploidization patterns in developmental and regenerative rat liver growth
Authors: Gerlyng P. , Åbyholm A. , Grotmol T. , Erikstein B. , Huitfeldt H. S. , Stokke T. , Seglen P. O. 
Published: May 2008

AbstractThe hepatocellular binucleation rate, measured as the percentage of binuclear cells amongst newly formed bromodeoxyuridine‐labelled and immunostained collage‐nase‐isolated rat hepatocytes, decreased from 12% to 4% between days 30 and 40 after birth, rose to 20% between days 50 and 60, and then declined again to the adult rate of about 10% at day 80. During regenerative growth following a two‐thirds partial hepatectomy, the rate of binucleation declined to about 3%, causing the fraction of binuclear cells to fall from 27% (before hepactectomy) to 5% (at 45 h after hepactectomy) as pre‐existing binuclear cells replicated and formed mononuclear daughter cells. Essentially all (97%) hepatocytes replicated at least once, starting their DNA synthesis at around 13 h and reaching a peak at 30 h, irrespective of ploidy and nuclearity. At later time points, the diploid hepatocytes had a higher labelling index than the polyploid cells, suggesting a greater tendency to go through several cell cycles.
Cell kinetic characterization of the epidermal growth factor dependent BALB/MK line using flow cytometric analysis of DNA content and iododeoxyuridine incorporation
Authors: Van Hooijdonk C. A. E. M. , Van Erp P. E. J. , Freund R. L. , De Jongh G. J. , Schalkwijk J. , Van De Kerkhof P. C. M. , Mier P. D. 
Published: May 2008

AbstractEpidermal hyperproliferation (psoriasis, wound repair) is the result of quiescent (G0) keratinocytes being recruited into the cell cycle. A detailed characterization of the cell cycle kinetic parameters of the mouse keratinocyte line (Balb/MK) has been carried out with the aid of bivariate iododeoxyuridine (IdUrd) and DNA analysis using flow cytometry, in order to establish whether it might provide a useful model for the study of the biochemical events controlling recruitment into the cell cycle. Balb/MK keratinocytes were cultured using low Ca2+ Dulbecco's modified Eagle's medium/F12 in the presence of 10% dialysed fetal bovine serum and 4 ng/ml epidermal growth factor (EGF). IdUrd labelling followed by flow cytometric analysis of trypsinized cells showed that about 95% of the population were actively cycling, with a cell cycle time of around 14 h and no significant contact inhibition. Omission of serum and EGF followed by IdUrd pulse‐labelling indicated that the cells progressively withdrew from the cycle and, after 16h, less than 10% incorporated IdUrd. Subsequent restimulation with serum resulted in a synchronized cohort of cells being recruited. Entry into the S phase of the cell cycle (IdUrd incorporation) started at 8 h and was maximal between 12 h and 16 h after stimulation. Restimulation with EGF alone reached a growth fraction of 87% after 24 h continuous labelling compared with 97% using serum together with EGF. Epidermal growth factor already showed a significant stimulation at 10 pg/ml compared with the controls. There is a broad plateau centred on 5 ng/ml, followed by a slight decline above this level. We conclude that the use of a cell line with defined cell cycle kinetic parameters which can be switched between the quiescent and cycling states in a fully defined medium will provide an ideal model for biochemical studies of the relevant signal transduction pathways in keratinocytes.
Changes in oncogene expression in ascite tumour cells during ageing
Authors: Biagetti M. , Fazia M. A. Della , Servillo G. , Viola‐Magni M. P. 
Published: May 2008

AbstractThe expression of two oncogenes, c‐myc and c‐fos, was studied in an ascitic tumour (ATPC+) at different times after implantation. The specific mRNA synthesis was analysed by Northern blot analysis. The presence of the oncogene proteins was shown by immunofluorescence using flow cytometry and referred to the distribution of the cells in the different cell phases. The results show that both oncogenes are expressed by ATPC+ tumour cells. c‐my is expressed 5, 8 and 12 days after implantation, although with a different intensity, and the protein is mainly present in S or S+G2 phase cells. The c‐fos oncogene is expressed only 12 days after tumour implantation and the cells labelled with the specific antibody are mainly in G1 phase. We conclude that c‐myc is principally correlated with proliferative activity, whereas c‐fos is expressed by non‐cycling cells.
A stochastic model for dual label experiments: an analysis of the heterogeneity of S phase duration
Authors: Kroll S. , Char D. , Kaleta‐Michaels S. 
Published: May 2008

AbstractWe develop a statistical approach for the study of S phase duration in experiments using sequential pulses of two thymidine analogues. Cell entrance into S phase is assumed to follow a possibly nonhomogeneous Poisson process, and the duration in S phase independently follows an unspecified distribution, thus allowing the possibility of variable S phase duration times for cells. Several conclusions regarding experimental design considerations are reached. The availability of three labelled cell subgroups comprising cells receiving exactly one of the two thymidine analogues or receiving both thymidine analogues at least doubles the efficiency of the mean S phase duration estimate compared to conventional estimates based on two labelled groups. Increasing the duration between the two thymidine analogue pulses can also dramatically increase the efficiency. The modelling technique was applied to fourteen uveal melanomas from patients who received in vivo injections of two thymidine analogues, bromodeoxyuridine (BrdUrd) and iododeoxyuridine (IdUrd). Counts of labelled cells were consistent with steady‐state time homogeneous entry into S phase and nonhomogeneous spatial entry into S phase.
Effects of IL‐11 on the growth of intestinal epithelial cells in vitro
Authors: Booth C. , Potten C. S. 
Published: May 2008

AbstractThe network of interacting factors that control proliferation in the intestinal epithelium is largely unknown. Recently, IL‐11 was found to protect animals from lethal doses of cytotoxic agents. Part of this protective action was ascribed to a reduced level of damage in the intestinal epithelium. Whether this was due to a direct effect on epithelial cell cycle progression was unclear. We have addressed this question in vitro and found that IL‐11 reversibly inhibited proliferation in untransformed small intestinal IEC18 cells. However, IL‐11 did not inhibit transformed SW620 or HT29 colonic cell lines. IL‐6 behaved in a similar manner to IL‐11. Thus, these results suggest that IL‐11 may be an ideal therapy adjuvant, protecting normal cells and further, these results suggest that IL‐11 may be involved in the normal growth controls in the intestinal epithelium. The inhibitory response evoked by IL‐11 is lost during carcinogenic transformation.
Effect of melphalan and hyperthermia on cell cycle progression and cyclin B1 expression in human melanoma cells
Authors: Orlandi L. , Zaffaroni N. , Bearzatto A. , Costa A. , Supino R. , Vaglini M. , Silvestrini R. 
Published: May 2008

AbstractWe have investigated the effect of mild hyperthermia (42°C) on the cytotoxic activity of a 1 h melphalan exposure in human melanoma cell lines. Hyperthermia did not affect cell growth of any culture, but it increased, to a different extent, melphalan cytotoxicity in all cell lines, with a reduction in the IC50 of 1.7 to 2.6‐fold. Flow cytometric analysis showed that in normal temperature conditions melphalan caused S phase cell accumulation, which was evident only at 24 h in JR8, M14 and 2/21 cell lines and was still persistent at 72 h in 2/60 cells. Moreover, in all cell lines, the delay in S phase was paralleled, or followed, by an accumulation of cells in G2+ M, which was transient in JR8 and M14 cells and persisted until 72 h in 2/21 and 2/60 melanoma clones. Hyperthermia caused a stabilization and prolongation of melphalan induced G2+ M accumulation in JR8 and M14 cells. Conversely, in 2/21 and 2/60 clones, cell cycle perturbations induced by the drug were similar under normothermic or hyperthermic conditions. Specifically, in JR8, for which the maximum enhancement by hyperthermia on melphalan cytotoxicity was observed, cell accumulation in G2+ M was still present 120 h after treatment. The accumulation was accompanied by an inhibition in the G2 ‐ M transition, as demonstrated by the significant reduction in the mitotic index of cells exposed to combined treatment compared to controls. Moreover, a bivariate distribution of cells stained for DNA and cyclin B1 showed that, following melphalan and hyperthermia treatment, the fraction of cyclin B1‐expressing cells paralleled the fraction of G2+ M phase cells, thus indicating that the inability of cells to enter mitosis was not ascribable to a reduction of cyclin B1 expression. On the whole, our results indicate that hyperthermia can stabilize the G2 accumulation induced by melphalan in human melanoma cells. Such a stabilization could contribute to the enhancement of melphalan cytotoxicity by heat, even though a strict correlation was not observed between the magnitude and persistence of the cell cycle perturbations and the extent of melphalan activity.
Transient inhibition of protein synthesis induces expression of proto‐oncogenes and stimulates resting cells to enter the cell cycle
Authors: Rosenwald I. B. , Setkov N. A. , Kazakov V. N. , Chen J.‐J. , Ryazanov A. G. , London I. M. , Epifanova O. I. 
Published: May 2008

AbstractThere is evidence that resting cells are able to produce molecules with antiproliferative activity, some of which behave as short‐lived repressor proteins. We suggest that transient inhibition of protein synthesis in resting cells would lead to a decrease in the levels of these negative growth regulators and might, therefore, promote mitogenic responses.We report that treatment of resting (serum‐deprived) NIH3T3 cells with cyclocheximide (CH) or puromycin induces expression of c‐fos, c‐jun and c‐myc proto‐oncogenes in a manner similar to that of platelet‐derived growth factor (PDGF). Actinomycin D (Act D) abrogates the induction of proto‐oncogene expression. Transient inhibition of protein synthesis by CH or puromycin also induces the resting NIH 3T3 and C3H 1OT1/2 cells to enter the cell cycle. Inhibition of new RNA or protein synthesis abolishes the proliferative response. These findings show that control mechanisms at both transcriptional and translational levels are operative in the resting cells treated with protein synthesis inhibitors.Cell fusion experiments with resting and serum‐stimulated NIH 3T3 cells revealed that brief pre‐incubation of resting cells with either PDGF, CH or puromycin abrogates their ability to suppress the onset of DNA synthesis in the nuclei of stimulated cells in heterodikaryons. However, the abrogative effect of PDGF disappeared in the presence of Act D, whereas the effects of protein synthesis inhibitors did not, indicating their independence of the induction of transcription. The data suggest that the observed effects of protein synthesis inhibitors are connected with elimination of some short‐lived negative growth regulators, since a brief translational arrest is sufficient for the resumption of DNA synthesis in the nuclei of stimulated cells blocked by resting cells in heterodikaryons.