bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow cytometric analysis of the recruitment of G0 cells in human epidermis in vivo following tape stripping
Authors: Boezeman J. B. M. , Bauer F. W. , de Grood R. M. 
Published: May 2008

Abstract. Tape stripping of human skin elicits a proliferative response of a synchronously‐dividing group of cells. The progress of this cohort of cells has been monitored using two windows in the cell cycle, one located in mid‐S phase and the other centred around G2+ M. The cellular DNA is measured with flow cytometry, the windows are defined by two ranges in the DNA histogram.The cohort can be described as the recruitment of cells from a pre‐existing G0 compartment which consists of 76% of all proliferative cells. The duration of the S phase is calculated to be 10.2 hr and G2+ M phase 5.1 hr. The cell cycle time of 39 hr for normal human keratinocytes derived from these figures is in line with recent values obtained by different techniques.
Cell population kinetics in pig epidermis: further studies
Authors: Morris G. M. , Hopewell J. W. 
Published: May 2008

Abstract. The cell population kinetics of the epidermis were studied in 4‐month‐old pigs. Mitotic figures were confined to the basal cell (L1) and the first suprabasal cell layer (L2). The mitotic index (MI) was 0.17 ± 0.04% for L1 and 0.08 ± 0.03% for L2. Labelled nuclei were distributed throughout the viable epidermis, the majority (79.1 ± 1.1%) were in L1 with 19.5 ± 1.2% in L2. The labelling indices (LI) in layers L1 and L2 were 7.1 ± 0.4% and 3.4 ± 0.1%, respectively. After labelling with two injections of tritiated thymidine [3H]TdR separated by 90 min, the LI increased to 8.2 ± 0.3% in L1 and to 4.0 ± 0.2% in L2. This increased labelling confirmed that cell proliferation occurs in both layers, L1 and L2, of the epidermis.The cell production rate (K) in L1 and L2 had an upper limit of 10.7 ± 1.0 and 6.2 + 1.8 cells per 1000 cells per hour respectively. The cell flow rate per hour (cell flux), into and out of the DNA synthesis phase (S), and the duration of DNA synthesis were determined from double‐labelling studies with [3H]TdR and [14C]TdR. The cell flux into and out of S was identical and was calculated as 0.6 ± 0.1%/hr (L1) and 0.5 ± 0.1%/hr (L2). Values for tS varied from 8 to 10 hr. The cell turnover times (tT) were in the range 89–129 hr and 180–261 hr for L1 and L2, respectively.Log normal curves were fitted to the fraction labelled mitoses data for L1 and L2. Values for tS for cells in L1 and L2 were 9.8 hr and 11.9 hr, respectively. tG2+ 1/2tM was 7.2 hr in L1 and 9.1 hr in L2.
Long duration of mitosis and consequences for the cell cycle concept, as seen in the isthmal cells of the mouse pyloric antrum. I. Identification of early and late steps of mitosis
Authors: El‐Alfy M. , Leblond C. P. 
Published: May 2008

Abstract. In this series of two articles, the duration of mitosis and that of the cell cycle were examined in a group of proliferating cells located in the mouse pyloric antrum and known as isthmal cells. However, before measuring the duration of mitosis, as described in the second article, it is necessary to identify the early and late steps of the mitotic process. This is attempted in the present article, in which the four phases of mitosis and the interphase are described in semithin (0.5 μm thick) Epon serial sections stained with hemalun. The frequency of these phases is then estimated.The beginning of prophase is indicated by the appearance in the nucleus of numerous 0.2‐0.3 μm thick basophilic threads. The threads gradually increase in thickness to become the typical chromosomes (about 0.7‐μm thick) observed at the end of prophase. Metaphase and anaphase show no remarkable features. At telophase, chromosomes separate from one another, gradually acquire pale segments along their length eventually to look like rows of alternating dark and light patches, and finally vanish.When prophases and telophases are defined in this manner, the enumeration of isthmal cells yields a high proportion of prophases (28%) and telophases (31%), but a low proportion of metaphases (1%) and anaphases (0.3%). Forty per cent of the cells are in interphase.
The Spleen Colony Technique. Ii. Errors In Estimation of the Fraction of Cfu‐S Synthesizing Dna
Authors: Znojil V. , Necas E. 
Published: May 2008

ABSTRACTA refinement of the method for determining the fraction of CFU‐s in the S phase is presented. the new procedures were tested by means of a model experiment in which the fraction of CFU‐s ‘killed’ was simulated by diluting the cell suspension. Another test was to determine the fraction of the CFU‐s in the S phase using duplicate samples.
Sodium‐N‐butyrate induces cytoskeletal rearrangements and formation of cornified envelopes in cultured adult human keratinocytes
Authors: Staiano‐Coico L. , Helm R. E. , McMahon C. K. , Pagan‐Charry I. , LaBruna A. , Piraino V. , Higgins P. J. 
Published: May 2008

Abstract The technique developed in our laboratory allows us to culture multilayered, stratified sheets of human keratinocytes, which can be used to cover the burn wounds of patients. Organization of cells in these cultures resembles stratum germinativum and stratum spinosum but there are only a few fully keratinized cells and the stratum corneum is not developed. Since the fully differentiated sheets may offer additional advantages as epidermal transplants, attempts were made to enhance the degree of differentiation in vitro. In the present study sodium‐N‐butyrate (NaB) was used as a differentiating agent and its effect on the cell cycle and cytoarchitecture of epidermal cells was investigated.Incubation of keratinocytes in the presence of 2.5 mM NaB induced the appearance of enucleated cornified envelopes, covering approximately 70–80% of the surface of the cultures. Their appearance correlated with a decrease in expression of keratin K13, previously shown to be inhibited during terminal differentiation of human keratinocytes. An increase in transglutaminase transferase activity was also observed. The induction of cornified layers also correlated with an increase in the amount of microfilament (MF)‐associated actin.NaB also induced changes in the cell cycle distribution of the keratinocyte cultures. A decrease in the proportion of S and G1B phase cells was paralleled by an increase in G1A cells, maximally expressed 30–48 h following addition of the inducer. Interestingly, NaB also induced a cell arrest in G2 phase. These cell cycle perturbations preceded the onset of keratinocyte differentiation. The results indicate that the enhanced differentiation of human keratinocytes in the presence of NaB may serve as a means to produce epidermal sheets with improved properties for transplantation in a clinical setting. It also serves as an in vitro model system to study the interrelationships between biochemical events and cell cycle changes accompanying differentiation.
DNA‐synthesizing cells in oral epithelium have a range of cell cycle durations: evidence from double‐labelling studies using tritiated thymidine and bromodeoxyuridine
Authors: Hume W. J. 
Published: May 2008

Abstract Mouse tongue epithelium is characterized by a circadian variation in the number of DNA‐synthesizing cells (labelling index, LI). Cells undergoing DNA synthesis were labelled with tritiated thymidine ([3H]TdR) at 0300 (peak LI) or 1200 h (low LI). The fate of these cells was assessed by injecting animals with bromodeoxyuridine (BrdU) at intervals from 12–48 h after [3H]TdR, to follow them from one cell cycle to the next. Labelling was revealed by combining [3H]TdR autoradiography with immunoperoxidase detection of BrdU in the same sections.A single peak in the appearance of double‐labelled cells was seen at 44 h, if [3H]TdR was given at 1200 h; following [3H]TdR at 0300 h, a peak of double labelling was seen at 48 h with the possibility of smaller peaks at 24 h and 36 h.These results show that the 24 h periodicity in LI in this tissue is associated with a predominant cell cycle duration of 44–48 h, but that a few cells cycle more quickly. Double labelling with [3H]TdR and BrdU provides a useful method for establishing cell cycle duration by labelling S‐phase cells in successive cell cycles.
Effect of sustained serum prolactin elevation on breast epithelial and myoepithelial cell proliferation
Authors: Stringer B. M. J. , Rowson J. , Greer W. , Thomas D. Wynford‐ , Williams E. D. 
Published: May 2008

Abstract.Oral administration of the dopamine antagonist perphenazine (0·01% in drinking water) to adult female Sprague‐Dawley rats led to a three‐ to fourfold increase in serum prolactin by the first time point sampled (day 2) and a sustained fourfold elevation from day 4 of treatment to the end of the experiment (day 54). In response, five‐ to sixfold (day 7) and three‐ to fourfold (day 4) peak elevations in the epithelial cell metaphase indices were seen in the breast lobular and ductular compartments respectively. Both indices fell to basal levels on day 14 but returned to a second, but diminished, peak on day 27. By day 54, the mitotic activity of the epithelium had fallen to just above basal levels in both compartments. A similar mitotic response occurred in the myoepithelial cells, clearly indicating that these must be considered an important cell kinetic component during breast stimulation. Breast epithelial cell number increased 13‐14 fold in the lobular but only two‐ to threefold in the ductular compartments in response to perphenazine administration. Again, similar responses were seen in the myoepithelial cell population. The major proliferative response therefore occurred within the lobular as opposed to the ductular compartment. A considerable discrepancy was shown between the cell number at each time point and that predicted on the assumption of constant cell death rate. We conclude that a growth desensitizing mechanism exists in the rat breast which limits breast growth in the presence of a sustained trophic hormone stimulation. Furthermore, we suggest that this limitation in breast growth is brought about by a mechanism which involves increased cell death in addition to decreased mitotic activity.
Tetraploid cycle in ageing solid tumours
Authors: Liautaud‐Roger F. , Dufer J. , Coninx P. 
Published: May 2008

Abstract. When the mouse mammary adenocarcinoma 755 (Ca‐755) reaches the plateau phase of growth, non‐cycling cells with a G2‐DNA content can be observed. They may belong to the diploid cell cycle but they could also be blocked in G0 or G1 of a tetraploid cycle. This hypothesis was tested in three ways: (1) non‐cycling G2 nuclei were stained with a combination of Feulgen and naphthol yellow which revealed two populations, one with a low protein content and the other with a high protein content– the latter may represent nuclei ready to begin a new phase of DNA synthesis; (2) Feulgen staining and autoradiography were performed after tritiated thymidine had been administered to mice continuously: this showed that there were cells synthesizing DNA with a DNA index above 2; and (3) cells having 80 chromosomes, corresponding to the tetraploid cycle, were found almost exclusively in the plateau phase tumours.On the other hand, the use of texture and DNA parameters of the Feulgen stained nuclei showed that they were concentrated in a diploid cycle for tumours in the exponential phase of growth and were divided between a diploid and tetraploid cycle for ‘plateau’ cells. Neither the cause for, nor the role played by, polyploid cells is known.
Different nucleolar antigen expression in resting and proliferating human lymphocytes as studied by fluorescence microscopy and flow cytometry
Authors: Dubben H.‐H. 
Published: May 2008

Abstract. The aim of this study was to investigate the use of a nucleolar antigen to discriminate between proliferating and resting cells. Antinucleolar antibodies (Si87) were obtained from a scleroderma patient. The specificity of immunostaining was verified and morphological changes in nucleoli were monitored using a fluorescence microscope. Fluorescence of propidium iodide‐stained DNA and nucleolar immunofluorescence were measured by flow cytometry.Following phytohaemagglutinin stimulation the number of nucleoli of normal human peripheral blood lymphocytes increased about 3‐fold, accompanied by enlargement of nucleolar size. Simultaneously a mean increase in total immunofluorescence per cell by a factor of three was detected. The method developed and applied here allows a discrimination between resting and proliferating human lumphocytes on the basis of their nucleolar antigen content.
Age‐related changes in the cell kinetics of rat foot epidermis
Authors: Morris G. M. , van den Aardweg G. J. M. J. , Hamlet R. , Whitehouse E. , Hopewell J. W. , Franke H. , Loeffler M. 
Published: May 2008

Abstract. The durations of the cell cycle and its component phases have been determined for the basal layer of the epidermis of the skin from the upper surface of the hind foot of the rat using single pulse [3H]‐thymidine labelling and the percent labelled mitosis (PLM) technique. Rats of three age groups were used, namely 7, 14 and 52 weeks. The duration of DNA synthesis (Ts) and the G2 plus M phase (Tg2± m) were comparable in 7‐week and 52‐week‐old rats (P > 0–1). The major difference between 7‐week and 52‐week‐old rats was in the duration of the G1 phase (Tg1). In 7‐week‐old rats Tg1 was 15.0 ± 0.8 h and in 52‐week‐old rats Tg1 was 31.2 ± 3.5 h. A consequence of this variation was that the overall duration of the cell cycle was longer in 52‐week‐old rats (53.9 ± 5.3 h) than in 7‐week‐old rats (30.1 ± 1.3 h).Difficulties were found in fitting a simple curve to the PLM data for 14‐week‐old rats. This suggests that the proliferative cell population of the epidermis of rats of this age group may be heterogeneous. A satisfactory fit to the data was obtained using a computer model which assumed that the proliferative population of the epidermis of 14‐week‐old rats was a mixture of cells with cell cycle parameters the same as those of the 7‐week and the 52‐week‐old rats. These two sub‐populations of relatively slowly and rapidly proliferating cells were present in the ratio of 2:1.
Cell proliferation kinetics of six xenografted human cervix carcinomas: comparison of autoradiography and bromodeoxyuridine labelling methods
Authors: van Oostrum I. E. A. , Rozemuller E. , Knol R. F. G. , Erkens‐Schulze S. , Rutgers D. H. 
Published: May 2008

Abstract. Cell kinetic and histologic parameters of six xenografted tumours with volume doubling times ranging from 6 to 43 d were investigated in order to obtain kinetic information on a panel of tumours to be used in radiobiological studies. The six tumours covered a range of histologies and their DNA indices varied from 2–7 to 1–4. The length of the cell cycle (Tc), potential doubling time (Tpot) and labelling index (LI) were determined by continuous labelling with [3H]TdR and autoradiography in three tumours. Tc varied from 30 to 40 h. Determinations of the length of the S phase (Ts) were found to be less reliable by this method.Data on Ts and LI were also determined in all six tumours using bromodeoxyuridine (BrdU) labelling and the single sample method; values of Tpot were slightly longer than those obtained via the autoradiographic method. In addition, multiple samples were taken after BrdU labelling. Tc was determined by fitting the data obtained from mid‐S, mid‐G2 and mid‐G1 windows to curves described by a damped oscillator. Data obtained via the mid‐S window were found to be most reliable. Generally, cell cycle times obtained by the BrdU method were longer than those observed with the autoradiographic method. Differences between the two methods could be explained by inaccuracies in the determination of Ts, LI and Tc and differences in the experimental approach.We consider the BrdU labelling method to be a suitable alternative for the time‐consuming autoradiography, if data on Ts or Tpot are sufficient. Due to difficulties in the reproducibility of the immunofluorescence staining and asynchronization of cells approximately 10 h after labelling, the method of windows analysis was affected by similar problems to those observed in interpretation of percentage labelled mitosis (PLM) curves. However, the method may serve as an alternative to determine cell cycle times in vitro and, if improved technically, in vivo. Careful comparison of the data obtained from mid‐S, mid‐G1 and mid‐G2 windows may increase the reliability of the determination of cell kinetic parameters.
Lack of correlation between thymidine kinase activity and changes of DNA synthesis with tumour age: an in vivo study in Ehrlich ascites tumour
Authors: Skog S. , He Q. , Tribukait B. 
Published: May 2008

Abstract. Thymidine kinase (TK) and its isoenzymes were studied in relation to age of Ehrlich ascites tumour cells growing in vivo. Various steps of the pathway of thymidine through deoxynucleotide metabolism were studied: [3H]‐thymidine cellular uptake and incorporation into DNA; the cellular nucleotide pools; and the concentration of thymidine in ascites. In addition, the proportion of cells in the various parts of the cell cycle and the bromodeoxyuridine labelling index were determined.Four isoenzymes at pi 41, 5‐3, 6–9 and 8‐3 were identified using isoelectric focusing. The TK activity declined with age of the tumour by about 90%, mostly due to a decrease of the isoenzyme at pi 8‐3. However, this decline was neither related to the changes in DNA synthesis rate of the cells with tumour age, nor to the proportion of cells in S‐phase or the bromodeoxyuridine (BrdU) labelling index. In contrast, the contribution of DNA synthesis via the thymidine salvage pathway relative to the total DNA synthesis increased from less than 1% at exponential growth to about 15% at plateau phase of growth. Blocking of DNA synthesis by aphidicolin did not change the TK activity. We therefore conclude that changes in TK activity and changes in cell growth are epiphenomena rather than causally related to each other.All nucleotide pools decreased with tumour age. The inhibition of TK by an increase in the deoxythymidine triphosphate pool could therefore be excluded. With a decrease of the TK activity during tumour growth, increasing amounts of TdR were excreted by the cells and accumulated in the ascites fluid. To explain our results on TK activity we propose a substrate cycle in which thymidine monophosphate supplied by de novo synthesis is dephosphorylated and is then either phosphorylated by TK to thymidine monophosphate or excreted by the cell.
Optimal conditions for immunohistochemical determination of the in vitro DNA synthesis labelling index with bromodeoxyuridine in head and neck cancer
Authors: Browman G. P. , Kanclerz A. , Booker L. , Daya D. , Archibald S. D. , Young J. E. M. , Goldsmith C. H. 
Published: May 2008

Abstract. The in vitro DNA synthesis labelling index was assessed immunohistochemically in 24 freshly obtained specimens of head and neck cancer using bromodeoxyuridine (BrdUrd) as the DNA precursor to determine the influence of BrdUrd concentration on labelling index (LI). Initially, tumour fragments were incubated in varying concentrations of BrdUrd from 2 to 100 μM for 2 h, and BrdUrd was detected with an anti‐BrdUrd monoclonal antibody using immunoperoxidase labelling. There was a dose‐response gradient with mean LI varying from 1·6% at 2 μMm BrdUrd to 8·8% at 100μM. The concentration‐response gradient best fit a quadratic model when LI was plotted against log BrdUrd concentration (r= 0·65, P < 0·0001).Eleven additional tumours were then studied to determine whether LI increased for BrdUrd concentrations above 100 μM. The mean LI at 125 μM and at 150 μM in these 11 tumours did not differ from the value at 100 μMm, suggesting a plateau at this level. The gradient effect accounted for 17% of the variance in LI, while 60% of the variance was explained by between tumour differences. Within individual tumours, three response patterns were observed: (i) LI rose at a constant rate to the highest concentration tested (n = 8), (ii) the LI plateaued or declined at high BrdUrd concentrations (n= 6); and (iii) there was a biphasic slope slope in which the rate of rise in the LI increased at the higher BrdUrd concentrations (n = 2).The data show that BrdUrd concentration is an important variable in the immunohistochemical assessment of the in vitro LI in head and neck cancer.
Cell proliferation in the small intestine and colon of intravenously fed rats: effects of urogastrone‐epidermal growth factor
Authors: Goodlad R. A. , Lee C. Y. , Wright N. A. 
Published: May 2008

Abstract. There is marked intestinal hypoplasia in the intestine of intravenously fed (TPN) rats. Recombinant urogastrone‐epidermal growth factor (URO‐EGF) reversed these changes by significantly increasing the length of the intestinal crypts. Crypt diameter, however, was not affected to the same extent. Few differences in labelling indices were seen between the orally fed and TPN groups, however, this was the consequence of the concomitant changes in crypt population.The number of mitoses and labelled cells per crypt, and thus the crypt cell production rates, were significantly decreased in the TPN group when compared to the orally fed. URO‐EGF significantly increased both proliferative indices and the number of dividing cells per crypt. Crypt cell production in the small intestine was restored to those levels seen in the orally fed rats, moreover, labelling per crypt in the colon was increased to more than twice that of orally fed rats. The location of the mean labelling position and the half maximum labelling position followed the changes in crypt length in the small intestine, but to a lesser extent; thus the growth fraction was significantly increased in the TPN rats in comparison with the orally fed and the URO‐EGF treated groups. Similar changes in these positions were seen in the colon, but the growth fraction was much reduced in the URO‐EGF treated rats, as a consequence of the large increase in crypt length without a concomitant alteration in label distribution.
Stimulator of proliferation of spleen colony‐forming cells in acute sterile inflammation
Authors: Milenković P. , Ivanović Z. , Lukić M. L. , Kataranovski M. , Lord B. I. 
Published: May 2008

AbstractThe presence and activity of a spleen colony‐forming cell (CFU‐S) proliferation stimulator was investigated in rat bone marrow after induction of sterile inflammation. Wistar rats were treated intraperitoneally with two 15 ml injections of 3.5% polyvinylpyrrolidone (PVP) at 18 h intervals, and the presence of CFU‐S proliferation stimulator determined in bone marrow 6, 20 and 24 h after the first injection. The marrow of these mice was used to condition medium which was then fractionated using Amicon Diaflo ultrafiltration membranes. The 30–50 kDa fraction, taken from 20 h post‐PVP‐bone marrow extract, was found to induce cycling of d8‐CFU‐S in normal mouse bone marrow. This activity was not related to the presence of interleukins‐1, ‐2 or ‐6 like activities in the material tested. The results demonstrate the existence of CFU‐S proliferation stimulator in the bone marrow of rats with sterile inflammation (i.e. in an in vivo tissue response to non‐specific cell stimulation), similar to that originally described as a macrophage product in mouse bone marrow after treatment with a variety of cytotoxic agents.