bluuebunny/crossref_metadata_2025 huggingface dataset:
CELL LOSS AND INFLUX OF LABELED HOST CELLS IN THREE TRANSPLANTABLE MOUSE TUMORS USING [125I]UdR RELEASE
Authors: Franko A. J. , Kallman R. F.
Published: May 2008

The [125I]UdR loss technique was used to estimate cell loss from RIF‐1, EMT6 and KHJJ tumors in order to determine the length of the delay between labeling and the beginning of the loss of labeled cells, and also to calculate a value for ø, the cell loss factor. To determine the importance of reutilization of label released from the gut and/or the influx of labeled host cells, the blood flow to some tumors was occluded during and for 30 min after injection of the label. Relatively small amounts of radioactivity entered occluded RIF‐1 tumors during 9 days after injection of [125I]UdR, indicating that reutilization of systemic label and influx of labeled host cells are not significant in this system. In contrast, substantial amounts of radioactivity entered occluded EMT6 and KHJJ tumors, reaching 40% of the total activity in non‐occluded tumors during 6 days following injection. After corrections were made for this influx of label, the [125I]UdR loss curves from RIF‐1 and EMT6 tumors were essentially exponential from the first day following injection of label. This was interpreted as indicating the loss of proliferating as well as non‐proliferating cells from both tumors. The cell loss factor derived from the [125I]UdR loss curves corrected for influx appeared to agree well with published values derived from analysis of percent labeled mitoses curves. In contrast, the corrected [125I]UdR loss curves from KHJJ tumors showed that loss of activity began three days after injection of label, indicating that primarily nonproliferating cells are lost from this tumor.
I. THEORETICAL OUTLINE OF A NEW METHOD TO ANALYZE TIME SEQUENCES OF DNA HISTOGRAMS
Authors: Zietz S.
Published: May 2008

A new mathematical method is presented to analyze a time sequence of DNA distributions taken from perturbed cell populations. The method, called FPi analysis, consists of plotting the time variation of the fraction of cells in selected DNA contents ‘windows’ of the histogram. It is shown that kinetic information about the flow of cells through the cycle after the perturbation can be estimated from the FPi curves. An analysis of the method reveals that the method yields accurate results for the instrumental and cytochemical variations obtainable by present technology. The value of the method lies in the fact that the information needed can be obtained directly from the measured DNA distribution, thus bypassing the problems with other methods which estimate the fraction of cells in a given phase directly from a single histogram.
II. USE OF THE METHOD TO MONITOR THE IN VIVO KINETICS OF CELL POPULATIONS PERTURBED BY HYDROXYUREA
Authors: Zietz S. , Lessin S. , Grattarola M. , Desaive C. , Nicolini C.
Published: May 2008

In a previous report, we described a new method called FPi analysis to analyze time sequences of DNA histograms taken from a perturbed population of cells. In this paper we utilize the method to analyze the in vivo kinetic response of bone marrow and of lung metastases of the B16 tumor to various chemotherapeutic agents. We show that the technique allows useful kinetic data to be obtained with minimal processing of the raw histograms, thus allowing fast analysis of the data. We also show that, in order to monitor the kinetic response of living tissues, it is essential to collect multiparameter distributions; to monitor only the one dimensional fluorescence histogram can give rise to misleading results. Using these multiparameter histograms, we are also able to monitor the growth fraction of the lung metastases during treatment, allowing discrimination between cell synchrony and cell recruitment from the resting compartment.
A RANDOM WALK MODEL FOR THE ANALYSIS OF THE ISOPRENALINE‐STIMULATED PROLIFERATIVE RESPONSE OF THE RAT SUBMAXILLARY GLAND
Authors: Hopper J. L. , Radley J. M. , Hodgson G. S.
Published: May 2008

In a series of papers, Hodgson, Radley and Koschel have studied the proliferative response of the rat submaxillary gland to the drug isoprenaline. They found that whereas the mitotic activity of the gland is normally very low, a single injection of isoprenaline will stimulate a wave of DNA synthesis and repeated administration at daily intervals, or longer, results in further waves of DNA synthesis. An explanation of these observations was proposed by Radley, Hodgson & Koschel (1976) who introduced the concept that administration of isoprenaline resulted in a period of enhanced ‘biochemical activity’ of the cells.

In this paper we present a stochastic model, based on a random walk model introduced by Hopper & Brockwell (1978), to represent quantitatively the concept of ‘biochemical activity'. It is shown that the parameters of this model can be adjusted to fit the observed data. It is noted that the simpler Smith & Martin model (1973), which is a special case of our random walk model, can also be fitted to the data. However, there is experimental evidence that contradicts an assumption of the Smith & Martin model, but agrees with the predictions of our model.

The random walk model also reveals that the different responses of the cell population to different injection schedules cannot be fully explained by changes in the cell population's biochemical activity distribution.
SELF‐MAINTENANCE ABILITY AND KINETICS OF HAEMOPOIETIC STROMA PRECURSORS
Authors: Chertkov J. L. , Gurevitch Olga A.
Published: May 2008

The use of repeated femoral curettages and repeated passages of ectopic haemopoietic foci has demonstrated the capacity of stromal precursor cells for repeated formation of haemopoietic microenvironment. During this process the stromal precursors undergo no less than ten to twelve mitoses. Precursors of bone marrow stroma proliferating slowly, if at all, in normal mice are triggered into cell cycle, as revealed by suicide methods, during formation of the ectopic haemopoietic focus.
A COMPREHENSIVE MATHEMATICAL MODEL OF STEM CELL PROLIFERATION WHICH REPRODUCES MOST OF THE PUBLISHED EXPERIMENTAL RESULTS
Authors: Loeffler M. , Wichmann H. E.
Published: May 2008

On the basis of experimental knowledge about haemopoietic stem cells a catalogue of fundamental statements is formulated. From this a simple mathematical model of haemopoietic regulation mechanisms is developed. The functional net effects of regulatory processes which are still unknown or unmeasurable are estimated using evolution arguments. The model is developed in three steps. It allows description of the self‐replication of stem cells after direct destruction as well as their reaction to increased or reduced needs in the erythropoietic system. The most important experimental data about changes in CFUe, BFUe and CFUe after acute or chronic irradiation, anaemia, hypoxia, hypertransfusion or direct erythropoietic stimulation can be reproduced within the model. The model allows us to understand most of the results of experimental stem cell research. Furthermore, it can be applied for a more precise analysis of the existing data. Predictions about the results of certain experiments can be made.
NEW METHODS OF CELL CYCLE ANALYSIS BASED ON THE SELECTIVE TAGGING OF CELLS EITHER AT THE BEGINNING OR END OF S PHASE
Authors: Kurz J. B. , Friedman D. L.
Published: May 2008

New techniques for cell cycle analysis are presented. Using HeLa cells, methods are described for the selection of a narrow window or cohort of lightly [3H]‐labeled cells located either at the very beginning or the very end of S phase. The cohort cells are tagged by a labeling procedure which entails alternating pulses of high and low levels of [3H]thymidine and are identified autoradiographically. Additional methods are described for following the progress of cohort cells through the cell cycle.

Theoretically, with the methods described, it should be possible to follow the ‘early S cohort’ cells as they exit from S phase, as they enter and exit M and as they enter the subsequent S phase. This would allow a determination of S, S + G2, S + G2+ M and T. It should theoretically be possible to follow ‘late S cohort’ cells in a similar manner, allowing a determination of G2, G2+ M and G2+ M + G1.

To test these predictions, several experiments are presented in which the progress of the two cohorts is monitored. The best data were obtained from the mitotic curves of cohort cells. For each of the cohorts, values were obtained for the time required for peak concentration of cells in mitosis, the coefficients of variation and of skew. The curve of cohort cells passing through mitosis is shown to fit a log‐normal curve better than a normal curve. In addition, the mitotic curves are used to estimate the length of M and to estimate the loss of cohort synchrony. Other uses of these methods are discussed.
THE CELL POPULATION KINETICS AND RESPONSE TO AN S‐PHASE SPECIFIC AGENT OF THREE TRANSPLANTABLE COLON TUMOR LINES
Authors: Simpson‐Herren Linda , Corbett T. H. , Griswold D. P.
Published: May 2008

The relative cell population kinetics of three transplantable murine colon tumor lines (Colon 26, 36 and 38) with different histological and metastatic characteristics were studied in relation to the response of each line to an S‐phase specific agent. The mean doubling times for the three lines between 0·1 and 1·0 g are similar (4·2 days) but marked differences are apparent in times to tumor appearance (0·1 g) and in median days to death. The length of the cell cycle is about one day and the length of the S‐phase 10–11 hr for Colon 36 and 38. The length of the cell cycle in Colon 26 is difficult to estimate by conventional methods but probably exceeds 24 hr and the S‐phase is 10–11 hr; [3H]TdR pulse labeling indices for Colon 36 and 38 decrease with time and tumor size from about 0·45 in 0·1 to 0·2 g tumors to about 0·33 at 3 g. The decrease in the [3H]TdR labeling index for Colon 26 is more pronounced (from about 0·38 at 0·1 g to 0·21 at 1·0 g). The shapes of the PLM curves and the [3H]TdR labeling index data are consistent with the observed sensitivity to an S‐phase specific agent (Palmo‐AraC, NSC 135962) in Colon 36 and the minimal response observed in Colon 26. Colon 38 is intermediate between Colon 36 and Colon 26 in kinetic properties and in response to the S‐phase agent.
Proliferation Inhibition of Murine Pluripotent Haemopoietic Stem Cells By Interferon Or Poly I:C
Authors: Gidáli Julia , Fehér I. , Tálas Margerita
Published: May 2008

The effect of mouse serum interferon (IF) in vitro and an inducer in vivo on the proliferation of a pluripotent stem cell population with high turnover rate was studied. Proliferation rate was characterized by the number of CFUs in the S phase of the cell cycle. Increased proliferation of bone marrow stem cell populations was produced either by irradiating the donor mice with 3·36 Gy (336 rad) 60Co‐gamma rays 7 days before the experiment or by incubating normal bone marrow cells with 10–11 M concentration of isoproterenol. IF considerably reduced the number of CFUs in S phase in both cases without reducing the CFUs content of the samples. Injection of IF inducer (4 mg/kg poly I:C) into regenerating mice also inhibited the proliferation of CFUs without decreasing the femoral CFUs level. Regeneration kinetics of CFUs from irradiated poly I:C‐treated mice ran parallel with that of irradiated untreated animals but showed a characteristic delay corresponding to approximately one CFUs doubling. A transient, non‐cytotoxic proliferation inhibitory effect of IF or IF inducer is, therefore, proposed.
Epidermis Extracts (Chalone) Inhibit Cell Flux At the G1‐S, S‐G2 and G2‐M Transitions In Mouse Epidermis
Authors: Elgjo K. , Clausen O. P. F. , Thorud E.
Published: May 2008

Epidermal cell flux at the G1‐S, S‐G2 and G2‐M transition was examined during the first 4 hr after injection of epidermis extract. the flux parameters were estimated by a combination of several methods. the G1‐S and S‐G2 transit rates were calculated on the basis of a double labelling technique with [3H]TdR, the G2‐M flux by means of colcemid and the relative proportion of cells in the S or G2 phase by means of flow cytometry. All experiments were performed both in early morning and late evening, corresponding to maximum and minimum rates of epidermal cell proliferation in the hairless mouse. the epidermis extract inhibited the S‐G and G2‐M transit rates to the same degree, while the inhibition of cell flux at the G1‐S transit was consistently stronger. In general, the inhibition of cell flux at the different transitions was most pronounced when the rate of cell proliferation was low and vice versa.
A Rapid Automated Stathmokinetic Method For Determination of In Vitro Cell Cycle Transit Times
Authors: Dosik G. M. , Barlogie B. , White R. Allen , Göhde W. , Drewinko B.
Published: May 2008

To provide a rapid method for examining cell cycle dynamics, we utilized continuous exposure of Chinese hamster ovary cells and human colon cancer cells to colcemid to block cycling cells in metaphase, suppressing re‐entry into G1. Changes in cell cycle compartment distribution were monitored by DNA flow cytometry. Analysis of the rate of G2+ M compartment accumulation after addition of colcemid permitted calculation of all cycle transit parameters. These compared favorably with data in the same cell lines determined by the fraction of labeled mitoses technique. Serial assessment of DNA flow cytometry after addition of colcemid permits rapid quantitation of cycle traverse rates.
A Critique of the Practice of Comparing Control Data Obtained At A Single Time Point to Experimental Data Obtained At Multiple Time Points
Authors: Burns E. R.
Published: May 2008

The normal circadian rhythm in DNA synthetic activity (DNA‐SA) in the tip of the mouse tongue is presented. When this rhythm, obtained from mice which were not treated (NT) or handled, was compared to the rhythms obtained from mice treated with saline (SAL) or 25 mg/kg isoproterenol (IPR), no alteration in the rhythm was observed after either treatment. the conclusion from this chronobiological, experimental design was that IPR had no effect on DNA‐SA in the tip of the tongue. However, when three single time points (08.00, 11.00 or 14.00) are selected from the SAL‐treated, control rhythm and compared to the multiple time point data from the IPR‐treated mice, three very different, statistically supported conclusions were reached.

The common practice of obtaining data at only one time point in control animals and comparing these data to data obtained from drug‐treated animals at multiple time points is an example of poor experimental design which results in erroneous conclusions and unnecessary confusion in the literature on in vivo research.
Alterations In Gastrointestinal Steady‐State Kinetics Associated With the Growth of Experimental Tumours
Authors: Kovacs C. J. , Evans M. J. , Schenken L. L. , Burholt D. R.
Published: May 2008

Changes in the growth kinetics of the intestinal epithelium were observed in mice bearing the Lewis lung carcinoma and the T1699 mammary adenocarcinoma and in rats bearing the H‐4‐II‐E2 hepatoma. Proliferative activity in the jejunal tissue was markedly depressed with increasing tumour burden. Simultaneously, a significant reduction in total crypt cellularity occurred, followed by a reduction in villus height. While the total number of proliferative cells per crypt decreased, the relative proliferative compartment within the shrinking crypt increased. the rate of mucosal DNA synthesis remained constant during the initial cytokinetic changes, falling only after proliferative activity of the intestine was reduced to less than 50% of control levels. No general correlation could be drawn from the three tumour models studied between the level of gastrointestinal proliferation and tumour size, tumour growth rate or loss of weight by the tumour‐bearing animals. However, intestinal proliferation was reduced by 50% when the tumour burden for each of the three tumours reached 6–8% of the host animal weight.
A Flow Cytometric In Vivo Chalone Assay Using Retransplanted Old Murine Jb‐1 Ascites Tumour Cells
Authors: Barfod N. M.
Published: May 2008

A flow cytometric in vivo chalone assay is described. Transplantation of old JB‐1 ascites tumour cells to new hosts induced an influx of tumour cells, with G1 DNA content, to the S phase. This induction could be reversibly and specifically blocked by injections of an ultrafiltrate of old JB‐1 ascites fluid.

The method described is superior to a previously published in vivo chalone assay using regenerating ascites tumours. Owing to a reduced variability in time of onset of DNA synthesis, a smaller scatter of observations is achieved and thus the number of mice per group may be reduced using the new method. In contrast to the older technique, the present one does not necessitate killing of mice during the observation period.
EFFECTS OF CHRONIC STEROID INGESTION ON GASTRODUODENAL EPITHELIAL RENEWAL IN THE RAT
Authors: Eastwood G. L. , Quimby G. Forrest , Laferriere J. R.
Published: May 2008

Steroids may predispose to peptic ulcer formation. One possible mechanism could be via alteration of normal epithelial renewal. to study the effects of steroids on gastroduodenal epithelial renewal, rats received hydrocortisone sodium succinate in the drinking water to deliver a dose of 10 mg/kg per day. Control rats received plain water. After 4 weeks, the rats were injected intraperitoneally with tritiated thymidine, to label proliferating cells, and killed 1 hr later, to determine measurements of epithelial proliferation, or 24 hr later to determine measurements of epithelial migration. Sections of fundus, antrum and post‐pyloric duodenum were processed for light microscopy and autoradiography. In fundic and antral mucosa, steroid treatment resulted in a reduction in the number of labelled cells and in the size of the proliferative zone and, in the fundus, the mucosal thickness was reduced. In the duodenum, although the number of labelled cells remained unchanged, steroid treatment did decrease the number of cells in the proliferative zone; further, crypt depth was reduced in steroid‐treated rats, but villous height was increased, resulting in an overall increase in mucosal thickness. Epithelial migration was also depressed in fundic and antral mucosa, but appeared to be accelerated in the duodenum of steroid‐treated rats. These studies indicate that although, in the duodenum, the effects of steroids on epithelial renewal are complex, in the stomach chronic steroid ingestion depresses epithelial renewal both in fundic and antral mucosa. This inhibition of epithelial renewal in the stomach may contribute to the ulcerogenic action of steroids by either rendering the mucosa susceptible to the effects of other ulcerogens or by retarding the healing of existing mucosal lesions.
Conditions Required For the Inhibition of In Vitro Growth of A Mouse Myeloma Cell Line By Adherent Bone‐Marrow Cells
Authors: Zipori D.
Published: May 2008

The in vitro growth of the MPC‐11 myeloma cell line was inhibited when these cells were co‐cultured with adherent cells from mouse bone marrow. This growth inhibition involved prolongation of the specific population doubling time of the MPC‐11 cell line. Control cultures of MPC‐11 cells exhibited an average doubling time of 14–15 hr, whereas in the presence of adherent layers the length of the doubling time was up to 28 hr. This prolongation in the doubling time did not depend on the duration of incubation, but on the relative proportions of tumour cells and adherent cells employed. MPC‐11 cells seeded in relatively high starting cell concentrations partially overcame the growth inhibition. the inhibitory activity of adherent cells from the bone marrow did not appear to be due to production of soluble factor(s), since media conditioned by adherent cells did not affect cell growth. Moreover, in modified co‐cultures in which MPC‐11 cells grew physically separated from the adherent layers, only marginal growth inhibition activity was observed. the possibility that cell‐to‐cell interactions lead to the inhibition of growth of MPC‐11 cells by adherent cells from the bone marrow, and the implications of these findings to the control of cell growth by the haemopoietic microenvironment, are discussed.
Circadian Rhythms In the Epithelial Cells and the Pericryptal Fibroblast Sheath In Three Different Sites In the Murine Intestinal Tract
Authors: Neal J. Valerie , Potten C. S.
Published: May 2008

Variations in percentage labelling (LI) and mitotic activity (mitoses per crypt) have been studied over a 24‐hr period in the epithelial cells and pericryptal fibroblast sheath (PCFS) of the small intestine, caecum, and colon of the mouse. All three tissues displayed clear, synchronized circadian rhythms in DNA‐synthetic activity in both the epithelial cells and PCFS. Peak values were coincident within a tissue, but staggered between tissues. In the epithelial cells, peak mitotic values were found between 3 and 6 hr after the peak LI values. the low level of mitotic activity in the PCFS appeared to be synchronized with the rhythms in the adjacent epithelia. the epithelial cells of the lowest crypt third displayed the clearest circadian rhythms. However, the PCFS cells at all levels produced similar curves. A craniocaudal wave of proliferative activity is proposed.
Density Centrifugation of Murine Fibrosarcoma Cells Following In Situ Labelling With Tritiated Thymidine
Authors: Sigdestad C. P. , Grdina D. J.
Published: May 2008

Murine fibrosarcoma (FSa) cells form at least five unique subpopulations after centrifugation in linear Renografin density gradients. Each of these subpopulations has been characterized with respect to selected kinetic parameters using pulse‐labelling techniques and flow microfluorometry (FMF) analysis. Tumour‐bearing mice were first injected intraperitoneally with a pulse label of tritiated thymidine ([3H]TdR, 50 μCi). Following 15, 30, 60 min or 24 hr these animals were injected with cold thymidine. Animals were killed, their tumours removed and made into suspension, and separated by density gradient centrifugation. Each gradient was fractionated and the density, cell number, tritium activity, and labelling index (LI) per fraction were determined. These data were then compared to FMF data for selected cell density bands. the results indicated a relatively higher uptake of [3H]TdR in the cells recovered at the lighter (1.06–1.12 g/cm3) as compared to the heavier (>1.12 g/cm3) densities. Following a 30‐min pulse, the LI's of light cells (<1.12 g/cm3) ranged from 25 to 30%, while the heavier cells (>1.12 g/cm3) had LI's between 10 and 15%. the unseparated control cells had an LI of 19%. Comparable results were found at the other times tested. In contrast, the FMF profiles describing the DNA contents of the cells banding in the gradient showed no difference in proportion of S‐phase cells among the separated subpopulations. This lack of correlation between the FMF determination of S‐phase cells and labelling index for the denser cell populations implies that DNA content alone is not an effective measurement of the functional activity of cells in solid tumours. Finally, the relatively reduced uptake of [3H]TdR by these denser cells suggests that they may have resided at relatively large distances from the functional vasculature in the tumour.
Combination of Budr‐Quenched Hoechst Fluorescence With Dna‐Specific Ethidium Bromide Fluorescence For Cell Cycle Analysis With A Two‐Parametrical Flow Cytometer
Authors: Böhmer R.‐M. , Ellwart J.
Published: May 2008

Stimulated or asynchronous L‐cells were grown in a BUdR‐medium, harvested and stained with a combination of 33258 Hoechst and ethidium bromide for analysis in a FACS II cell sorter. the u.v. laser line served as a light source for exciting the Hoechst fluorescence, the ethidium bromide fluorescence being excited mainly by energy transfer from the Hoechst dye. the quenched Hoechst fluorescence was analysed between 410 nm and 480 nm, the DNA specific EB fluorescence at beyond 630 nm. Thus, not only the actual location of each cell in the cycle could be determined, but also its initial location at time 0 of the experiment, together with its moment of division (BUdR‐quenched Hoechst fluorescence). This method could become a powerful tool in many investigations dealing with cell cycle perturbations in culture.
Presence of pluripotent haemopoietic precursors in vitro (CFU‐mix) in haemopoietic tissues from mice of W/Wv genotype
Authors: Hara H. , Ohe Y. , Noguchi K. , Nagai K. , Tsuyama K. , Kitamura Y.
Published: May 2008

Abstract. The presence or absence of haemopoietic precursors, which produce mixed colonies in vitro (CFU‐mix) was examined in the bone marrow and spleen of (WB x C57BL/6) F1‐W/Wv mice. Despite the failure of macroscopically evident colonyformation in the spleens of irradiated mice, haemopoietic cells of W/Wv mice did produce macroscopically‐evident mixed colonies containing erythroid cells, macrophages, and often megakaryocytes, in culture medium. The size and constitution of mixed colonies derived from W/Wv mice were comparable to those of mixed colonies from congenic +/+ mice. The present results appear consistent with in vivo haemopoiesis in the W/Wv mice, which is obviously deficient, but sufficient for survival.
Partial purification of a low molecular weight inhibitor of epidermal DNA synthesis
Authors: Quirk A. V. , Pain R. H. , Davison Maureen , Shuster S.
Published: May 2008

Abstract. An attempt has been made to purify factors present in aqueous extracts of pig epidermis which inhibit epidermal cell proliferation. A lipophilic factor of low molecular weight (less than 10,000), has been shown to inhibit DNA synthesis as measured by the uptake of tritiated thymidine in mouse ear epidermis. Purification by alcohol precipitation, ethyl acetate extraction and silicic acid column chromatography produced a fifteen‐fold increase in the specific activity of the inhibitory action. It seems likely that aggregation or absorption of this low molecular weight factor may explain the high molecular weight of epidermal cell proliferation inhibitors previously studied, as well as the difficulty in their characterization.
Radiosensitivity variation during the cell cycle in pronuclear mouse embryos in vitro
Authors: Domon M.
Published: May 2008

Abstract. The radiosensitivity of pronuclear mouse (B6D2 F1 x ICR) embryos has been measured in vitro as a function of time during the cell cycle. This was done by measuring the dose of X‐rays (LD50) required to prevent development of 50% of the pronuclear embryos to the blastocyst stage in 5 days of culture. The LD50 was found to vary from 1 to 2 Gy during the period from G1 to the first cleavage. The cell cycle in the pronuclear embryo was analysed by [3H]thymidine autoradiography. Compared with earlier studies on two‐cell mouse embryo radiosensitivity, the pronuclear embryos appear to be more sensitive to radiation than the two‐cell embryos. If, however, one considers the radiation sensitivity on a blastomere basis, the pronuclear embryos are not different in their radiation sensitivity from the two‐cell embryos. Thus, during the early cleavage stages of mice, radiosensitivity is mainly governed by the content of cells of various cell cycle ages in the embryo.
Mechanisms of phytohaemagglutinin (PHA) stimulation of normal human lymphocytes: ‘trigger’, ‘push’ or both?
Authors: Gibbs J. H. , Potts R. C. , Brown R. A. , Robertson A. J. , Beck J. Swanson
Published: May 2008

Abstract. The growth in volume of human peripheral blood lymphocytes after stimulation with various concentrations of PHA was measured with an electronic particle counter. The percentage of growing cells and averaged values describing their growth rates during the elapsed period of culture were estimated by fitting to the observed data the volume distributions derived from a mathematical model. With sub‐optimal doses, the percentage of cells stimulated, and their incremental growth rate, increased with increasing dose of PHA, but the time‐course of recruitment into the G1‐phase was similar with all PHA concentrations studied. The results provide strong support for the ‘trigger’ hypothesis that there is a distribution of stimulation thresholds within the lymphocyte population: consequently, increasing mitogen concentration will be expected to result in increased numbers of responding cells within the suboptimal concentration range.
Cellular proliferation kinetics of the murine sarcoma induced by the Moloney sarcoma virus
Authors: Smadja‐Joffe F. , Bousse‐Kerdiles M. C. Le , Klein B. , Malaise E. P. , Jasmin C. , Degiorgis V.
Published: May 2008

Abstract. Cell proliferation kinetics of the sarcoma induced by Moloney virus was studied in newborn Swiss OFl mice.

After in vivo injection of tritiated thymidine, followed by autoradiography, it was shown that the majority of cells were actively proliferating (labelling index; 31%, growth fraction 78%). The mean cell cycle was 16 hr and cell loss was relatively low (cell loss factor 48%). The study of tumour specific activity with time after a single [in vivo] injection of [3H]dR or [125I]UdR did not demonstrate the same degree of cell loss as that calculated by autoradiography. This result is consistent with a massive reutilization of radioactivity released by normal tissues.
Enhanced triggering of stem cell proliferation after two doses of hydroxyurea
Authors: Nečas E. , Činátl J.
Published: May 2008

Abstract. Hydroxyurea (HU) injected into experimental mice increases the proliferation rate of the pluripotent haemopoietic stem cells (CFUs). This effect can be enhanced if hydroxyurea is administered in two doses, separated by 2 hr. The effect does not seem to be caused by more extensive bone marrow damage.
Circadian variations in influx and efflux of the S phase in a partially synchronized cell system Double‐labelling with [3H]thymidine in the epithelium of the hamster cheek pouch
Authors: Møller U. , Keiding N.
Published: May 2008

Abstract. By means of a double‐labelling experiment, circadian variations in the kinetic parameters of the S phase of the hamster cheek pouch epithelium were studied. The evaluation of the experiment included a recently developed correction for deviations from the strict pulse interpretation of the labelling technique.

Pronounced circadian variations were found in S phase influx and efflux; the diurnal mean of both was estimated as 0.5%/hr, when based on measurements of all nucleated epithelial cells. Variations in S phase influx seem mainly responsuble for the diurnal variation in cell proliferation, although diurnal variation in DNA synthesis rate, and thus in mean transit time, was also found. The increases in LI and influx were closely correlated and related to the beginning of the dark period.

A circadian variation in cell number was also observed.
The spatial organization of the hierarchical proliferative cells of the crypts of the small intestine into clusters of ‘synchronized’ cells
Authors: Potten C. S. , Chwalinski S. , Swindell R. , Palmer M.
Published: May 2008

Abstract. A statistical analysis of the distribution of [3H]TdR‐labelled cells in longitudinal and transverse sections of crypts from the ileum of the mouse, indicated that there was a strong tendency for labelled or unlabelled cells to be associated in short vertical runs and lateral clumps, suggesting the presence of clusters of labelled cells on the sides of the crypts. A model is discussed for the cellular spatial organization of the crypt that proposes a vertical alignment of the cells within branches of the proliferative cell lineage. The model would predict vertical alignment of partially synchronized cells as well as some lateral clumping.

In the present studies mitoses were not observed at higher levels in the crypt than labelled (S phase) cells. This observation would be predicted by the non‐random spatial organization suggested by the model.

The model would also make certain predictions concerning cell migration. These are discussed in relation to cell migration studies which include evidence that migration continues in the absence of mitotic activity.
The relative spatial distribution of erythroid progenitor cells (BFUe and CFUe) in the normal mouse femur
Authors: Frassoni F. , Testa Nydia G. , Lord B. I.
Published: May 2008

Abstract. Femoral mouse bone marrow cells were separated into axial and marginal fractions, in order to investigate the relative concentration of erythroid progenitor cells (BFUe and CFUe) with respect to their location across the diameter of the femur. Two areas of high incidence of early progenitor cells (BFUe) were identified: one lying near the bone surface with a peak at about 410 μm radial distance from the axis of the bone; the other nearer the centre of the bone with a peak at about 270 μm. The more immature BFUe were found in higher proportion in the marginal peak. In contrast, CFUe, apart from very low concentration values in the vicinity of the bone surface, demonstrated a fairly uniform distribution throughout the marrow. The present results indicate that the distribution of erythroid progenitor cells within the bone marrow is not random. The haemopoietic tissue seems to exhibit a well‐defined structure that may be relevant in regulating proliferation and differentiation processes.
The kinetics of villus cell populations in the mouse small intestine
Authors: Wright N. A. , Irwin M.
Published: May 2008

Abstract. The cell population kinetics of the villus epithelium of the mouse have been analysed with respect to the size, flux and time. Microdissection methods were employed to measure the villus cell population size and yielded reproducible, precise results. There was a proximodistal negative size gradient in villus cell population and, in those villi of normal morphology, there was a good correlation with the usual morphometric estimators such as height and row count, although correlation was improved by a product variable consisting of a height multiplied by a width parameter.

Flux onto the villus is the product of the crypt cell production rate, which was measured by a metaphase arrest method using vincristine and crypt microdissection, and the crypt:villus ratio; net villus influx was maximum proximally in the bowel, where the largest villi were found, and decreased distally. The distribution of transit times of labelled cells to the crypt: villus junction and to the villus tip was measured, allowing the measurement of the median villus transit time.

Comparison of the measured villus transit time with the theoretical transit time calculated from the villus influx and population size gave results consistent with a steady state hypothesis. It was found, at each level of the small intestine studied, that the number of epithelial cells on the villus was equivalent to the total number of crypt cells associated with the villus.
The kinetics of villus cell populations in the mouse small intestine
Authors: Wright N. A. , Al‐Nafussi A.
Published: May 2008

Abstract. Cytosine arabinoside was used to kill large numbers of proliferating crypt cells in the mouse small intestine, and the recovery sequence was analysed in terms of the villus population size, the crypt population size, the crypt:villus and the net villus cell influx; because the crypt:villus ratio changed considerably, it was found appropriate to express the crypt population in terms of the crypt cell mass per villus in order to relate it to the villus cell population.

All parameters measured showed a series of damped oscillations over the experimental period, and analysis of the relationship between the several population changes strongly suggest that negative feedback control mechanisms are responsible for the response pattern. The importance of measuring the correct kinetic parameters in growth control studies on renewing epithelia is stressed.
Space flight effects on haemopoietic stem cells of the bone marrow of rats
Authors: Vacek A. , Tkadleĉek L. , Shvets V. N. , Bartoni;čkov A. , Viklick S. , Rotkovsk D. , Serova L. V. , Michurina T. V.
Published: May 2008

Abstract. Changes in the number of haemopoietic stem cells (CFU‐s) were studied in rats during the recovery day and selected post‐recovery days after an 18–19‐day flight on biosatellites Cosmos 936 and Cosmos 1129. There was a decrease in the CFU‐s number of the bone marrow of rats on the recovery day. On the 6th day post‐recovery the CFU‐s number was still depressed, while on the 25th day post‐recovery it was elevated above control value. The differentiation ratio of transplanted bone marrow cells was not altered by space flight.
Kinetic analysis of megakaryocyte numbers and ploidy levels in developing colonies from mouse bone marrow cells
Authors: Williams N. , Jackson Heather
Published: May 2008

Abstract. The kinetics of megakaryocyte formation from mouse bone marrow cells in semi‐solid medium was studied directly in the culture dish by staining the cells for acetylcholinesterase after drying the cultures. A WEHI‐3 cell‐conditioned medium (WEHI‐3 CM) was used as a general source of stimulus for megakaryocyte colony formation. The addition of peritoneal exudate supernatant as well as WEHI‐3 CM increased the frequency of megakaryocyte colonies detected. Colonies containing acetylcholinesterase‐positive cells were first detected at day 3. Maximum numbers of 25–40 megakaryocyte colonies per 105 nucleaet mouse bone marrow cells were observed from days 7 to 11. The mean number of cells within each colony increased progressively with time of culture, and a modal range of 11–20 cells was obtained by day 7. Between 3 and 200 cells per colony were generally detected. A continuous distribution of the number of megakaryocytes per colony suggests that the clonable precursor cells are not synchronized either with respect to maturation stage or with respect to their capability to undergo nuclear endoreduplication. The addition of peritoneal exudate supernatant to the cell cultures increased the DNA levels of megakaryocytes grown in the presence of WEHI‐3 CM but did not affect the number of cells per colony. The DNA content of colony megakaryocytes was measured after staining the cells with Feulgen reagent. A modal DNA value of 8 N was observed between days 4 and 7 for megakaryocytes stimulated with WEHI‐3 CM. In the presence of both WEHI‐3 CM and peritoneal exudate supernatant, the DNA content of megakaryocytes increased with the time of cell culture. Modal DNA values increased from 8 N at days 4 and 5, to 16 N by day 6. In these optimally stimulated cultures, 44% of colony megakaryocytes were 32 N or greater, a proportion higher than in normal bone marrow, but similar to that seen in the marrow of acutely thrombocytopenic animals. It is concluded that megakaryocytopoiesis in cell cultures is not a strictly controlled process with respect to cell division and endomitosis and that when certain culture conditions are employed, megakaryocyte development in vitro might reflect that seen in a stressed animal condition.
Self‐replication of somatostatin cells in the antral mucosa of rodents
Authors: Lehy T.
Published: May 2008

Abstract. The possibility that antral somatostatin cells have a self‐replicating activity has been studied in three species of rodents: mice, rats and guinea‐pigs, after a flash tritiated thymidine injection. The immunocytochemical staining of somatostatin cells, using specific antiserum, was combined with radioautographic procedures. The labelling index for somatostatin cells–and for gastrin cells indentified on serial sections–was established after counting a large number of cells at the optical microscope level, on parallel tissue strips removed throughout the entire antrum.

A significant percentage of the somatostatin cell population synthesized DNA. Values were similar for the three species of rodents ranging from 0.8 to 1.1%, that is slightly higher than the percentage of labelled gastrin cells, which was 0.6–0.7%. After a 36‐hr continuous infusion of radioactive precursor in one rat, the labelling index observed remained low; 2.33% for somatostatin cells and 1.68% for gastrin cells. Colchicine injection in mice allowed the observation of mitotic figures in well differentiated somatostatin cells. Four hours after that injection, the mitotic index was estimated roughly at 0.3%.

Thus, evidence has been presented that in rodents a fraction of the antral somatostatin cell population is capable of dividing, similar to the situation in gastrin cells.
The proliferative response of rat liver parenchymal cells after partial hepatectomy A methodological study comparing flow cytometry of nuclear DNA content and in vivo and in vitro uptake of thymidine
Authors: Digernes V. , Brønstad G. , Sand T.‐E. , Christoffersen T.
Published: May 2008

Abstract. DNA synthesis in rat hepatocytes, from livers regenerating after 70% hepatectomy, was assessed by flow cytometric determination of nuclear DNA content and by incorporation of [3H]thymidine. Parenchymal liver cells were isolated by collagenase perfusion and low‐speed centrifugation. Nuclei from the isolated cells were prepared for flow cytometry by a treatment with detergent, pepsin and RNase, and stained with ethidium bromide. Parallel samples of cells were incubated with [3H]thymidine and analysed for rate of incorporation of radioactivity into DNA and for labelling index determination.

The flow cytometric measure of the replicative response, i.e. the presence of cells with S‐phase DNA content within the diploid and tetraploid cell populations, was compared with the incorporation of [3H]thymidine. For each of fourteen animals, including two control rats and twelve partially hepatectomized animals killed either before (at 13 hr after hepatectomy), at the onset (16 and 18 hr) or at the peak (24 hr) of regenerating activity, a fairly good correlation was found between the different methods. Satisfactory resolution of the flow cytometric detection of S‐phase cells was indicated by a sorting experiment using an Ortho (system 50‐H) cell sorter which demonstrated that after [3H]thymidine injection in vivo 88% of the diploid and 84% of the tetraploid S‐phase nuclei were labelled, while labelling in the G1‐fractions was only 2 and 7%, respectively.
Analysis of Mopc‐315 Plasmacytoma By Elutriation and Flow Cytometry
Authors: Flentje Dagmar , Flentje Michael , Valeriote Fred , Sapareto Stephen
Published: May 2008

ABSTRACT Intravenously transplanted murine plasmacytoma MOPC‐315 cells were separated from normal spleen cells from a tumour‐bearing mouse by elutriation and characterized according to morphology, immunologic properties and clonogenicity. Morphologically, both lymphocytoid and plasmacytoid cells were separable by elutriation. Flow cytometry correlated DNA content and intracytoplasmic IgA content and demonstrated two distinct populations, both in cell cycle, but with markedly different cellular IgA levels. Density gradient separation characterized the lower‐density cells with lower IgA content and higher clonogenicity. From these studies a model of cellular differentiation is proposed.
Dna Flow Cytometry of Breast Carcinoma After Acetic‐Acid Fixation
Authors: Meyer John S. , Micko Steven , Craver Jeffrey L. , McDivitt Robert W.
Published: May 2008

ABSTRACT Aqueous acetic acid was used to fix and store specimens of tissue prior to dissociation into nuclear suspensions for flow cytometric quantitation of DNA. the optimum concentration was 20 volumes of glacial acetic acid in 80 volumes of distilled water. Both neoplastic and benign nuclei were easily released from the fixed tissue blocks by slicing and shaking. Residual undissociated tissue was suitable for microscopic examination to confirm its identity. the nuclei fluoresced brightly after staining with propidium iodide, and yielded histograms similar to those from unfixed samples. Acetic‐acid fixation resulted in slightly broader G1 and G0 peaks in the DNA histograms in comparison to unfixed cells, but fluorescent debris was less and correlation between the flow cytometric S‐phase fraction (SPF) and in vitro thymidine labelling index (TLI) was better than with unfixed cells. Twenty‐one of thirty‐nine acetic‐acid‐fixed breast carcinomas had DNA indices in excess of 1.0 (increased nuclear DNA content in comparison to benign cells), and eighteen had DNA indices of 1.0 (normal or near‐normal). the SPF was usually in excess of the TLI, but the two were significantly correlated (r= 0.72, P>0.0001). However, a significant correlation of SPF with TLI held only for the group with DNA index < 1.0. DNA indices < 1.0 were associated with high SPF and TLI, and high SPF and TLI each associated with low content of estrogen receptor.
Non‐Exponential Growth By Mammalian Cells In Culture
Authors: Skehan Philip , Friedman Susan J.
Published: May 2008

The concept of exponential growth by mammalian cells in culture is based upon the apparent linearity of semilogarithmic data plots. This method of graphical analysis is known to be an unreliable test of the exponential hypothesis. We have re‐examined the question of growth exponentiality using the more sensitive method of Smith plots, in which specific growth rate is plotted against either time or density on transformed graphical coordinates which linearize the mathematical expression of the growth hypothesis being tested. With exponential growth, data points fall on a horizontal straight line when specific growth rate is plotted against time or density. Using both our own and literature data, we have performed Smith plot analyses on the growth of 125 different mammalian and avian cell lines. of these, only eleven exhibited an exponential phase. the remaining cell lines all had non‐exponential growth patterns. the most common of these consisted of an initial period of growth acceleration followed by a later phase of deceleratory growth. A smaller number of lines exhibited deceleratory kinetics at all times after plating. We conclude that mammalian cell growth in culture is predominantly non‐exponential, and that the apparent exponentiality of semilogarithmic data plots is usually a methodological artifact.
On the Equivalence of Mathematical Models For Cell Proliferation Kinetics
Authors: Sundareshan Malur K. , Fundakowski Richard
Published: May 2008

Various types of mathematical models, such as partial differential equations, ordinary differential equations and difference equations, are available in the literature to describe the kinetics of cell proliferation, and different studies of cell kinetic phenomena have been conducted using these models. This paper discusses the equivalence between the different models identifying the conditions and approximations under which one type of models may be derived from another. Such an equivalence study is highly useful for an integration of the diverse results that have been obtained using different models in order to gain a more complete understanding of cell kinetic phenomena.