bluuebunny/crossref_metadata_2025 huggingface dataset:
The Short‐Term Effects of A Single Injection of Isoproterenol On Proliferation In the Submandibular Gland, Parotid Gland and Oesophagus In Vivo
Authors: Bybee A. , Tuffery A. R.
Published: May 2008

Abstract. Mitotic and labelling indices were studied in the submandibular, parotid and oesophageal cells of male mice within the first 6 hr (but particularly within the 1st hr) of a single injection of isoproterenol or saline, using the metaphase arrest agent (vincristine) which was previously tested for efficacy in submandibular gland. There was a significant increase in the metaphase index of the salivary glands over control values 5, 15, 30, 45 and 60 min after isoproterenol. In contrast, there were no significant changes in the metaphase index of basal cells of the oesophagus. There was no significant change in the labelling index in isoproterenol‐treated mice in comparison with saline‐injected control animals. Possible explanations for the rapid mitotic response in murine salivary glands are considered; a rapid efflux from G2 into mitosis is thought to be the most likely.
Synchronized Growth In Human Epidermis Following Tape‐Stripping: Its Implication For Cell Kinetic Studies
Authors: Rijzewijk J. J. , Boezeman J. B. M. , Bauer F. W.
Published: May 2008

Abstract. A after stimulation A recent investigation of the hyperproliferative activity of human epidermis following sellotape stripping showed a wave of cell divisions with a maximal percentage of cells in mid‐S phase at about 39 h after stripping. Here we present a study over the period of 52‐76 h following stripping, showing a second wave of cell divisions with a maximal percentage of cells in mid‐S at about 63 h. This indicates an average cell cycle time of about 23 h. Human epidermis after tape‐stripping provides us with a useful model of synchronized growth, allowing us to study drug influences on cell kinetics accurately.
Scoring Mitotic Activity In Longitudinal Sections of Crypts of the Small Intestine
Authors: Potten C. S. , Roberts S. A. , Chwalinski S. , Loeffler M. , Paulus U.
Published: May 2008

Abstract. Various counts have been made of the number of mitotic figures in whole crypts and sections of crypts of the small intestine of the mouse. Samples were analysed from animals killed at different times of the day and at different times after administration of vincristine. Measurements have been made of the size of mitotic and interphase nuclei and of the radial position of mitotic figures. the correction factor, f, which is required to take into account the enhancement of mitotic counts in sections as a consequence of their centripetal position has been investigated. the results indicate the following: (1) transverse sections of the crypt differ from longitudinal sections if they involve cutting the intestime before fixation which may result in a relaxation of the crypt and its widening by 25%; (2) columnar cell nuclei have a shape that resembles a sphere flattened so that the average diameter is 20% greater in crypt transverse sections; (3) mitotic nuclei tend to be about half‐way between the crypt edge and the central axis of the crypt; (4) between about four and seven times more mitotic figures have their mitotic axis parallel to the long axis of the crypt; (5) about one‐third of all mitotic figures in a crypt are seen in a longitudinal section of the crypt. If this is related to the number of cells in the crypt as a whole and in a section, a correction factor fd for the mitotic index of 0.59 is obtained; (6) the correction factor fT derived from the shape and position of the mitotic figures measured in 3 μm longitudinal sections is 0.53; (7) relating cell cycle and mitotic accumulation data using a computer‐based model of the crypt also permits a correction factor fmod to be estimated. This gives a value of 0.66. When sectioned material is used to calculate a mitotic index the most appropriate correction factor is fD; for mouse small intestine it is 0.59.
Effects of Continuous Low Dose‐Rate Irradiation: Computer Simulations
Authors: King C. R. , Nath R. , Rockwell S.
Published: May 2008

Abstract. The effects of continuous low dose‐rate irradiation are studied with a computer model that incorporates cell kinetics and the accumulation and repair of radiation damage. This theoretical approach independently explores the effects on survival curves of a phase block, inherited damage and proliferation by dying cells. the computer model is a Monte Carlo simulation which follows the evolution in time of the family trees of a growing cell population under continuous irradiation. the model uses as input the measured phase‐specific survival curves for acute exposures and the cell kinetic parameters to generate survival curves for continous low dose‐rate irradiations. Cell survival curves for Chinese hamster lung cells (V79) for dose rates ranging from 15 to 500 cGy/h have been generated using various model assumptions. the model shows that for these cells a G2 block will maximize cell killing for an optimum dose rate near 75 cGy/h. the effect on survival curves of inherited damage, as well as that of the proliferation by dying cells, is shown to increase monotonically with decreasing dose rates, and to be quite large at low dose rates.
Identification of ‘Non‐Proliferating’ B16 Melanoma Cells Using Monoclonal Antibody (Ad203) Against the M1 Subunit of Ribonucleotide Reductase
Authors: Wong W. S. F. , Mann G. J. , Tattersall M. H. N.
Published: May 2008

Abstract. Ribonucleotide reductase catalyses a critical reaction in DNA synthesis. Its M1 subunit is present during all proliferative phases of the cell cycle, but apparently not in the quiescent phase Go. We have used a monoclonal antibody (AD203) directed against the M1 subunit to distinguish immunocytochemically proliferating from non‐proliferating cultured B16 mouse melanoma cells during exponential growth. the presumption that AD203 unstained cells constituted a non‐proliferating fraction was tested by simultaneously counting the cells that failed to incorporate bromodeoxyuridine (BrdU) into DNA during a prolonged BrdU exposure. the proportion of cells which did not incorporate BrdU was found to correlate closely with the proportion not staining with AD203 and therefore presumably lacking the M1 subunit. the respective morphological features of AD203 stained and unstained cells were found not to differ significantly.
Mineralization of Adult Mouse Bone Marrow In Vitro
Authors: Schoeters G. E. R. , de Saint‐Georges L. , Van Den Heuvel R. , Vanderborght O.
Published: May 2008

Abstract. Murine adult bone marrow exhibits mineralizing capacity in vitro as is demonstrated by the new in vitro assay we report here. In less than 2 weeks after the onset of the cultures, mineralization is obtained in more than 80% of the marrow cultures. Moreover, morphological studies reveal that during incubation phenotypic changes related to osteogenic differentiation occur at the extracellular matrix as well within cell populations. Well banded collagen is synthesized. Matrix vesicles and needles of hydroxy‐apatite crystals are observed via transmission electron microscopy. Osteoblast‐like cells are present with membrane‐associated alkaline phosphatase activity. the mineralization is specific for cultured bone marrow and is not observed in cultured spleen fragments as is shown via 85Sr uptake, calcein uptake and histomorphology. No inducing agent is added to the tissue culture medium except for 10% fetal calf serum, beta‐glycerophosphate (10−2 M) and ascorbic acid. However, the prerequisite for obtaining mineralization is the three‐dimensional structure of the marrow in culture. the in vitro organ culture we developed may provide the opportunity to identify which marrow cells have osteogenic potential and to investigate the mechanisms triggering differentiation towards osteogenesis.
The Growth and Life of A Monoclonal Crypt
Authors: Chen W. , Meinzer H. P. , Sandblad B.
Published: May 2008

Abstract. A computer simulation of a highly dynamic model for the birth, growth and adult life of a monoclonal crypt in the intestine was developed starting with a single precursor stem cell. the intestinal epithelial system was studied and observed in analogy to ‘in vivo’ experiments. the model output, e.g. the geometric shape of a crypt, mitotic index, labelling index and the crypt length distribution in adult state, was compared with experimental data. There was evidence from the simulation that a certain steady state in the adult life could be reached regardless of some harmless influences in post‐natal life, e.g. the influence of being weaned or non‐weaned. the model is based on our hypothesis of the generation‐controlled proliferation mechanism and at the same time is a confirmation of it.
Circadian Rhythms Are Suppressed In Hyperproliferative Mouse Epidermis
Authors: Brown W. R. , Furukawa R. D. , Ramsay C. A.
Published: May 2008

We 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

Urogastrone (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

Between 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%.
Flow cytometric correlation of the c‐myc oncoprotein and cell cycle kinetics of HL60 leukaemia during induced maturation with cytosine arabinoside and dimethylsulphoxide
Authors: Dent G. A. , Ayscue L. H. , High K. A. , Leglise M. C. , Ross D. W.
Published: May 2008

Abstract The c‐myc oncogene codes for a DNA binding protein that functions in a cell cycle‐related manner. A useful model for studying the relationship of c‐myc expression with cell cycle kinetics is the HL60 cell line. HL60 cells constitutively express high levels of c‐myc mRNA; however, the level can be down‐regulated as the cells are induced to differentiate. We have developed a flow cytometric assay for correlating c‐myc oncoprotein levels with DNA content. C‐myc oncoprotein levels were additionally correlated with c‐myc mRNA levels as determined by slot blot hybridization. Dimethylsulphoxide (DMSO) and cytosine arabinoside were used to induce granulocytic and monocytic maturation respectively. Treatment of HL60 cells with DMSO leads to an increase in the per cent of cells in G1/G0 and a decrease in mean c‐myc mRNA and oncoprotein levels. The cells with G1 DNA content show the greatest decrease in c‐myc protein. ARA‐c treatment of HL60 cells leads to a slowing and an accumulation of cells in S phase with a moderate decrease in mean mRNA and only a slight decrease in mean c‐myc protein levels. These data support the hypothesis that c‐myc is involved in the switch from G1 to G0.
Tumour‐induced altered gastrointestinal steady‐states: absence of MHC restriction in the paraneoplastic gastrointestine
Authors: Kovacs C. J. , Evans M. J. , Langweiler M. , Gould B. J. , Gooya J. M.
Published: May 2008

Abstract The growth of a number of experimental rodent tumours including the Lewis lung tumour (LLca) progressively compromises the integrity of the host's gastrointestine by inducing cytokinetic alterations in the small bowel resembling those generally defining the intestinal phase of a graft‐versus‐host reaction (GVHR). To determine whether the induction of this paraneoplastic gastrointestine (PGI) involves, similar to a GVHR, a disparity between the MHC of the donor (LLca tumour) and the recipient (host), PGI development was evaluated in various LLca tumour‐bearing murine strains that were either ‘syngeneic’[C57BL/6 and BL/10 (H‐2b)], ‘semisyngeneic’[B6D2F1 (H‐2bd) and B6C3F1 (H‐2bk)] or ‘allogeneic’[C3H/HeJ (H‐2k) and DBA/2 (H‐2d)] to the H‐2b LLca tumour. The temporal appearance and magnitude of a PGI developing in either LLca‐syngeneic or semi‐syngeneic hosts, but not the allogeneic strains, suggested that the mechanism(s) involved in PGI development, like the GVHR, was restricted by the MHC. Subsequent studies using congenic strains [B10.A (H‐2k) and B10.D2/nSn (H‐2d)], however, demonstrated that the mechanism(s) responsible for the PGI was restricted by the non‐MHC loci of the C57BL mouse. These observations were supported by the appearance of a LLca‐induced PGI in various B10.A congenic strains carrying mutations at the I‐A or I‐E/I‐J loci of the MHC. Not unlike the intestinal phase of a GVHR, development of the PGI required the participation of enhanced mucosal mast cells which were limited in the WCB6F1 (S1/S1d) but not the (+/+) murine strains. These observations are discussed in light of the postulated premature migration of immature thymocytes that accompany tumour growth and their ability to non‐specifically enhance (or suppress) cell mediated immune reactions in the host.
Cell proliferation in the bone marrow, thymus and spleen of mice studied by continuous, in vivo bromodeoxycytidine labelling and flow cytometric analysis
Authors: Crippen T. L. , Jones I. M.
Published: May 2008

Abstract We have applied the technique of labelling dividing cells with bromodeoxyuridine (BrdUrd) in combination with in vivo continuous labelling, propidium iodide (PI) staining for DNA content, and flow cytometric analysis, for the determination of cell proliferation in bone marrow, thymus and spleen of mice. The percentage of BrdUrd labelled cells increased as a function of exposure time in a tissue specific manner for each of the three tissues. Thymus and bone marrow had cell populations which exhibited different kinetics for the accumulation of label: (1) those that cycled and became labelled within 2–3 days (88% in 2 days for bone marrow, 84% in 3 days for thymus); (2) those that cycled during the remainder of the 6 day infusion period (11% of bone marrow and 13% of thymus cells); and (3) those that did not cycle during the 6 day period studied (<2% of bone marrow and 3% of thymus cells). In contrast, the spleen exhibited a slower, constant accumulation of labelled cells. After six days of infusion a large proportion of spleen cells (50%) had not become labelled. These results suggest that a larger proportion of spleen cells are long lived than indicated by other methods. We also have found that the period of labelling with BrdUrd extended several days beyond the period of infusion. This method will be very useful in studying perturbations of cell populations induced in mice exposed to toxic agents.
Cultured human keratinocytes: discrimination of different cell cycle compartments based upon measurement of nuclear RNA or total cellular RNA content
Authors: Staiano‐Coico L. , Darzynkiewicz Z. , McMahon C. K.
Published: May 2008

Abstract Correlated measurements of total cellular RNA and DNA of cultured human keratinocytes by flow cytometry, followed by multivariate analysis, discriminate three distinct subpopulations of cells differing in RNA content. The first subpopulation is comprised of small cells resembling basal cells of epidermis, with low RNA content and long (100–300 h) generation times. The second subpopulation consists of keratinocytes resembling cells in the spinous layer of epidermis, characterized by increased RNA content and shorter (35–40 h) generation times. The third subpopulation consists of the largest, keratinohyalin‐containing cells which remain in G1 and undergo terminal differentiation. In contrast to total cellular RNA, correlated measurements of DNA and nuclear RNA reveal that: (1) entrance of all cultured cells from G1 into S phase occurs only after accumulation of the same, threshold amount of nuclear RNA; hence there is only a single population of S + G2+ M‐phase cells; (2) there are two distinct subpopulations in G1, one with minimal nuclear RNA content and another with increased RNA. Stathmokinetic experiments indicate that the G1‐phase cells with low nuclear RNA have distinctly longer residence times in G1 compared to cells with high nuclear RNA content. Thus, measurements of the total cellular RNA versus nuclear RNA content reveal kinetically distinct cell subpopulations. Whereas total cellular RNA content correlates more with differentiation, nuclear RNA content reflects primarily the kinetic properties of the cell.
Cell cycle phase dependent emergence of thymidylate synthase studied by monoclonal antibody (M‐TS‐4)
Authors: Shibui S. , Hoshino T. , Iwasaki K. , Nomura K. , Jastreboff M. M.
Published: May 2008

Abstract A method of identifying thymidylate synthase (TS) at the cellular level was developed using anti‐TS monoclonal antibody (M‐TS‐4), a monoclonal antibody created against purified TS from a HeLa cell line. In HeLa cells and four human glioma cell lines (U‐251, U‐87, 343‐MGA, and SF‐188), TS was identified primarily in the cytoplasm. Autoradiographic and flow cytometric studies showed that TS appeared mainly in the G1 phase and subsided early in the S phase; thus, the G1 phase can be divided into TS‐positive and ‐negative fractions. Nuclear TS was not demonstrated unequivocally with M‐TS‐4, and the relationship between nuclear TS and DNA synthesis could not be determined. Although the percentage of TS‐positive cells was larger than the S‐phase fraction measured by autoradiography after a pulse of tritiated thymidine or by the immunoperoxidase method using BUdR, the ratios were within a similar range (1.2–1.4) in all cell lines studied. Therefore, the S‐phase fraction can be estimated indirectly from the percentage of TS‐positive cells measured by M‐TS‐4. Because the emergence of TS detected by our method is cell cycle dependent, M‐TS‐4 may be useful for biochemical studies of TS and for cytokinetic analysis.
DNA synthesis in Langerhans’cells of mouse ear epithelium revealed by tritiated thymidine autoradiography and histochemical staining for non‐specific esterase and beta‐glucuronidase activity
Authors: Hume W. J. , Moore J. K.
Published: May 2008

Abstract The proportion of Langerhans’cells in DNA synthesis in normal mouse skin was assessed by combining tritiated thymidine [3H]TdR autoradiography with enzyme histochemistry. After injection of [3H]TdR, ear skin was treated in two ways. Epithelial sheet preparations were stained for the presence of non‐specific esterase and cytospin preparations of epithelial cell suspensions were stained for beta‐glucuronidase activity. The labelling index (p± SE mean) for cytospins, 40 min after injecting [3H]TdR, was 1.6 ± 0.15%, doubling to 3–4% from 7–17 days after injection. The sheet preparations showed the proportion of label attributable to paired Langerhans’cells rising from 18% at 40 min after injection, to approximately 45%, on days 1–4 after injection. These results suggest that the proliferation of Langerhans’cells in normal mouse skin might be higher than was previously thought to be the case.
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.
Local regulation of haemopoietic stem cell proliferation in mice following irradiation
Authors: Ali A. M. , Wright E. G. , Riches A. C.
Published: May 2008

Abstract Changes in the kinetic state of pluripotent haemopoietic spleen colony forming cells (CFU‐S) and of the CFU‐S proliferation stimulator have been studied following whole‐body X‐irradiation. Rapid recruitment of CFU‐S into cell cycle by 30 min after irradiation was observed following low doses (0.5 Gy) but a delay of 6 h occurred after higher doses (1.5 and 4.5 Gy). These changes in proliferative state correlated with the presence of the CFU‐S proliferation stimulator. CFU‐S irradiated in vitro in bone marrow plugs were also recruited into cycle illustrating directly the local nature of the feedback mechanism. CFU‐S removed from 1.5 Gy irradiated recipients at a time when they were not in cycle were not responsive to the CFU‐S proliferation stimulator. The CFU‐S proliferation stimulator was produced by Ia positive cells in the irradiated bone marrow. The regulation changes occurring shortly after irradiation cannot simply be controlled by the size of the CFU‐S compartment.
On the pattern of ameloblast migration
Authors: Nataatmadja M. I. , Orams H. J. , Reade P. C.
Published: May 2008

Abstract The kinetics of ameloblast cells in continuously growing guinea pig molars were studied using autoradiography. The results showed that there was no direct relationship between ameloblast migration rate and ameloblast production rate, which indicated that ameloblasts actively migrated coronally. It was found that ameloblast migration rate was maximal at the root apex, and then reduced to a minimum value as the ameloblasts left their proliferative compartment and migrated coronally. A multiple regression model was found to be the most suitable one to represent the ameloblast migration pattern.
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.
A reproducible technique combining tritiated thymidine autoradiography with immunodetection of bromodeoxyuridine for double labelling studies of cell proliferation in paraffin sections of tissues
Authors: Hume W. J.
Published: May 2008

Abstract. A method is described to combine tritiated thymidine autoradiography with immunoperoxidase detection of bromodeoxyuridine on the same paraffin sections. It overcomes the varied technical artefacts we encountered when first attempting to combine these techniques and results in preparations with extremely low peroxidase and autoradiographic backgrounds. In particular, we find it is important to avoid the use of detergents during immunostaining, otherwise grain counts are reduced and autoradiograph exposures need to be greatly increased, and to avoid excessive peroxidase staining which makes it difficult to visualize silver grains in the overlying emulsion. The advantages of a method to remove emulsion films using acid‐alcohol, allowing the same sections to be dipped twice with a long and a short autoradiographic exposure, are presented. The routine combination of high quality tritiated thymidine autoradiography with clean immunoperoxidase staining of bromodeoxyuridine‐positive nuclei provides a new and powerful cell kinetic, double‐labelling method to augment existing techniques e.g. by labelling the same cells undergoing DNA synthesis in successive cell cycles.
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.
The cell cycle dependence of c‐sis gene expression: artifactual conclusions in cells prepared by chemical but not physical techniques
Authors: Press R. D. , Jacobberger J. W. , Samols D. , Goldthwait D.
Published: May 2008

Abstract. The c‐sis oncogene encoding the B‐chain of platelet‐derived growth factor (PDGF) may be involved in an autocrine growth stimulation of tumours expressing the PDGF receptor, such as glioblastomas and sarcomas. To investigate whether expression of c‐sis RNA is regulated in a cell cycle dependent manner, human A172 glioblastoma cells were synchronized by either centrifugal elutriation or chemical blockage with the DNA synthesis inhibitors hydroxyurea or aphidicolin. In non‐perturbed elutriated cells, c‐sis RNA levels were lower in the S phase of the cell cycle than in the G1 phase. In contrast, the chemically synchronized cells revealed a transient rise in c‐sis RNA shortly after drug release, in early S phase. The RNA changes occurring after release from drug inhibition represent cell recovery from drug induced metabolic disturbances rather than true cell cycle dependent effects.
The changes of BPA level in 31 cases of children with aplastic anaemia and its clinical significance
Authors: Wang W. , Tan H.
Published: May 2008

Abstract. Burst‐promoting activity (BPA) was measured in the sera from 31 children with aplastic anaemia (AA). BPA levels were elevated in most of the children with A A (65‐2%), the mean value (137.7 ± 18.4%) being significantly higher than that in normal children (69.6 ± 9.4%), in children in the recovery period and in children with non‐aplastic anaemia. There was a negative relationship between the BPA level in children with AA and the peripheral haemoglobin concentration. The BPA level was higher in those whose duration of illness was shorter than 1 year. In three cases of AA caused by chloramphenicol and benzene hexachloride and one case of congenital pure red cell AA, the BPA level was not elevated. Eleven patients received fetal liver cell suspensions intravenously (FLI). After FLI the BPA level in their sera was significantly reduced. According to these results, it appears that the elevation of BPA level is a special phenomenon of A A. The measurement of BPA in serum is helpful for differentiation between AA and other kinds of anaemia. The elevation of the BPA level in serum is a biological compensation for the haematopoietic disorder, and the measurement of BPA in the serum of patients with A A may be helpful in evaluating the haematopoietic condition.
Basement membrane components stimulate epithlialization of intestinal defects in vivo
Authors: Thompson J. S.
Published: May 2008

Abstract. Subepithelial tissues have an important role in the structure and function of the intestinal epithelium. Basement membrane components (BMC) stimulate epithelial cell migration and differentiation in vitro. The aim of this study was to determine the effect of BMC and/or interstitial tissue collagen (type I) on the in vivo intestinal regenerative response to intestinal patching. Twenty rabbits had two 2 times 5 cm ileal defects patched with the serosal surface of adjacent caecum. Group 1 (n = 5) were controls; group 2 (n = 5), group 3 (n = 5) and group 4 (n = 5) had collagen, collagen plus BMC, and BMC respectively applied to the distal patched defect. Animals were killed at 7 d and evaluated grossly for epithelialization and contraction of the defects. Epithelial coverage was greatest in the distal patch of group 4 animals (62 + 9%) and was significantly greater than the group 4 proximal patch and control values (43 ± 7 and 40 ± 14%, P < 0–05). Contraction was similar in all groups (38 ± 5 to 45 ± 5%). Crypt cell production rate, villus height, and disaccharidase activities were similar in all groups. BMC stimulated epithelialization via a local mechanism since only the distal patch was affected. Type I collagen did not stimulate epithelialization and inhibited the effect of BMC. Since crypt cell production rate was similar in all groups, the enhanced epithelialization seen with BMC is primarily due to increased cell migration.
Lysosomal inhibitors stimulate resting NIH 3T3 cells to proliferate
Authors: Rosenwald I. B.
Published: May 2008

Abstract. Lysosomal inhibitors (amino acid methyl esters) and platelet‐derived growth factor stimulate resting NIH 3T3 cells to enter the S period. Incubation of cells in medium containing lysosomal inhibitors causes an increase in protein accumulation and does not disrupt lysosomes. The results indicate that proliferative homeostasis depends partially on the metabolic status of the cell and that catabolic processes activated in resting cells negatively influence prereplicative reactions.
Measurement of c‐myc protein content and cell cycle kinetics of normal and spontaneously transformed murine mastocytes by bivariate flow cytometry
Authors: Giaretti W. , Vinci A. Di , Geido E. , Marsano B. , Minks M. , Bruno S.
Published: May 2008

Abstract. Progressive in vitro culturing of interleukin‐3 (IL‐3) dependent normal murine mastocytes (PB‐3) resulted in a variant cell line (PB‐1) able to grow without exogenous IL‐3 and which was tumorogenic in syngenic mice. Bivariate flow cytometry was used to evaluate the c‐myc protein and DNA content of PB‐3 and PB‐1 cells. The c‐myc protein was detected by specific monoclonal antibodies. Kinetic characteristics of PB‐3 and PB‐1 cell lines, namely, the duration of the G1, S and G2+ M cell cycle phases were also evaluated using the bromodeoxyuridine (BrdU) pulse‐chase method and BrdU/DNA flow cytometry. Levels of c‐myc protein in PB‐1 cells were about twofold higher than those of PB‐3 cells in all cell cycle phases. Mean duration of the cell cycle (Tc) was 15‐3 h for PB‐3 cells and 12‐4 h for PB‐1 cells. Shortening in Tc for the transformed cells was due to a decrease of nearly 30% in mean duration of the G1 phase (from 8 h to 5.7 h). No significant differences were found in the duration of the S and G2+ M phases. These results indicate that acquired IL‐3 independency in vitro and tumorogenicity of PB‐1 cells were accompanied by a doubling of c‐myc protein level and by a parallel shortening, or bypass, of the regulatory events within the G1 phase of the cell cycle.
Kinetics of the development of accelerated cell‐cycle transit resulting from inhibition of DNA replication in the previous cycle
Authors: Tolmach L. J. , Labanowska J.
Published: May 2008

Abstract. Shortening of the generation cycle in cells in which DNA synthesis had been temporarily inhibited in the previous generation, which has been reported several times in recent years, has been confirmed in HeLa cells. As in the previous studies, the shortening is attributable to accelerated transit of G1 resulting from the accumulation, during the inhibition, of a factor needed for initiation of DNA replication. It is shown that partial (85–96%) inhibition with any one of three inhibitors is effective when the inhibitor is added in G1 or in S, but more complete (99%) inhibition is effective only if the inhibitor is added after cells have entered S. In addition, cells begin to respond to the inhibition after a lag that increases as DNA synthesis in the early part of S is progressively inhibited with aphidicolin, indicating that competence to respond is achieved only after cells have reached a particular point in the replication of their genome.
Disruption of microtubules induces an endogenous suicide pathway in human leukaemia HL‐60 cells
Authors: Martin S. J. , Cotter T. G.
Published: May 2008

Abstract. Terminally differentiated HL‐60 cells undergoing programmed cell death (apoptosis) in culture were found to have a disrupted microtubular network. Treatment of undifferentiated HL‐60 cells with microtubule‐disrupting agents alone was found to induce apoptosis en masse in these cells. In contrast, disruption of microfilaments did not induce apoptosis; instead these cells underwent necrosis, the pathological mode of cell death. Apoptosis in response to microtubule disruption in HL‐60 cells was characterized by cell shape changes, nuclear condensation followed by fragmentation and the separation of the cell into numerous intact fragments, termed apoptotic bodies. Apoptosis of these cells was further confirmed by DNA analysis, which demonstrated the activation of an endogenous endonuclease which cleaved the DNA of these cells into oligonucleosomal fragments. Microtubule disrupting agents were found to exert these effects over a wide range of doses. Apoptosis was also inducible in HL‐60 cells, in a dose‐dependant manner, by the calcium ionophore A23187. Since microtubules are known to be highly sensitive to intracellular calcium fluctuations, this suggests that calcium influx could act at the microtubule level in efTftctino annntnsis
New methods for calculating kinetic properties of cells in vitro using pulse labelling with bromodeoxyuridine
Authors: White R. A. , Terry N. H. A. , Meistrich M. L.
Published: May 2008

Abstract. The transit times of Chinese hamster ovary cells through the phases of their cell cycle were measured using dual parameter flow cytometry to measure DNA content and the presence of monoclonal antibodies to bromodeoxyuridine. Up to four separate populations can be accurately measured: unlabelled cells in G2+ M; labelled cells that have not yet divided; labelled cells that have already divided; and the unlabelled cells that were originally in G1 plus the cells that were originally in G2+ M and have since divided. The fractions of cells in these populations can be easily followed in time and the usual kinetic properties can be estimated from these fractions, or combinations thereof, including the times through G1, S, G2+ M and the cycle time. We present equations for analysing this type of data and comment on which equations are most appropriate for measuring specific kinetic properties of the cells.
Effects of vitamin A deficiency on cell proliferation and morphology of trachea of the hamster
Authors: Chopra D. P. , Cooney R. A. , Taylor G. W.
Published: May 2008

Abstract. Regulation by vitamin A of cell proliferation and differentiation of epithelial tissues is well‐established. Deficiency of vitamin A in experimental animals leads to the development of hyperplasia and squamous metaplasia. The objective of the present study was to examine, for young hamsters, the effects of variable levels of the vitamin in the liver and trachea, on cell proliferation and morphology of tracheal epithelium and on body weights. Newly born litters were maintained on vitamin A‐supplemented and vitamin A‐deficient diets, and various parameters were examined at different ages. Retinol and retinyl palmitate levels were determined by high performance liquid chromatography. For animals on the supplemented diet, concentrations of liver retinyl palmitate and retinol increased progressively with age, reaching highest levels of approximately 84 and 1 ‐9 μg/g liver, respectively, at 28 d. In contrast, in animals on the vitamin A‐deficient diet, the retinyl palmitate and retinol levels decreased progressively, reaching the lowest levels of approximately 0–32 and 0–09 μg/g, respectively. No significant reduction in retinol was observed in the trachea of animals maintained on the deficient diet for at least 20 d; their tracheas were depleted of retinol at 28 d. No vitamin A‐associated differences were, however, observed in the labelling indices, growth fraction or in the morphology of the tracheal epithelium. Both the control and vitamin A‐deficient animals gained weight progressively until 36 d of age, although the weight of animals in the latter group remained below those in the former group. These results show that mild‐to‐severe deficiency of vitamin A had no effects on cell proliferation or tracheal morphology of the hamster. The hyperplasia and squamous metaplasia in the trachea occurs only at an extreme vitamin A‐deficiency when the tissue levels of the vitamin are depleted.
Subpopulations of primary adult murine epidermal basal cells sedimented on density gradients
Authors: Morris R. J. , Fischer S. M. , Klein‐Szanto A. J. P. , Slaga T. J.
Published: May 2008

Abstract. Epidermal cells were harvested from the dorsal skin of adult mice by trypsinization and were sedimented through continuous density gradients of Percoll, formulated to separate basal cells of different buoyant density. Five fractions from the gradients were characterized with regard to the number of cells present, their viability and morphology and their basal origin. Suprabasal keratinocytes remained primarily at the top of the gradient; basal keratinocytes sedimented throughout. With increasing density, a relative enrichment was observed: (i) for [3H]‐thymidine and [3H]‐benzo[a]pyrene label‐retaining (slowly cycling) keratinocytes; (ii) for keratinocytes that could proliferate in vitro in the continuous presence of 0–1 μg ml‐1 of 12‐0‐tetradecanoylphorbol‐13‐acetate; (iii) for cells from untreated as well as initiated epidermis able to proliferate under conditions where calcium induces terminal differentiation; and (iv) for primary in vitro clonogenic keratinocytes from normal epidermis. The relative enrichment for epidermal basal cells having characteristics thought to be associated with immaturity and with the initiation and promotion of skin carcinogenesis suggests that density gradient sedimentation could be used in conjunction with other methods for the eventual purification of epidermal progenitors.
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.