bluuebunny/crossref_metadata_2025 huggingface dataset:
Thymus‐Derived Inhibitor of Lymphocyte Proliferation
Authors: Rijke E. O. , Lempers H. C. M. , Ballieux R. E.
Published: May 2008

A thymus crude factor (TCF) isolated from bovine thymus tissue has been tested for its effects on the proliferation of various murine cells. Specific inhibition in vitro has been found for DNA synthesis in murine T and B lymphocytes which appears not to be based on cytotoxicity. Moreover, TCF, when administered to mice, also interferes with the DNA synthesis in lymphoid tissue in vivo. Our data are suggestive for the presence in TCF of an endogenous ‘chalone‐like’ inhibitor of lymphoid cell proliferation in vitro and in vivo.
A Method For Measuring the Generation Time and Length of Dna Synthesizing Phase of Clonogenic Cells In A Heterogenous Population
Authors: Wu A. M.
Published: May 2008

Information on the cell cycle of progenitor cells in haemopoietic tissue is useful for understanding population control under physiological and abnormal conditions. Unfortunately, methods that have been developed for measuring cell cycle parameters are applicable only to cells of homogenous populations and not to morphologically non‐recognizable progenitor cells such as colony forming units (CFU) that are present at low frequency in a heterogenous population. to circumvent this difficulty, a method was developed to measure CFU cell cycle parameters based on specific killing of cells in S phase by [3H]thymidine ([3H]TdR). This was done by estimating the number of CFU killed following exposure of the cell suspension to [3H]TdR for various time periods. Since cycling CFU are continuously entering S phase, a linear curve relating the percentage CFU‐kill to the length of exposure of the cells to [3H]TdR in culture can be obtained. the slope of the curve (percentage kill/hr) indicates the rate that CFU enter the S phase and travel through the cell cycle. the inverse of this value will then represent a time period for CFU to move through a complete cell cycle (generation time). the length of S phase can then be obtained by multiplying generation time by the fraction of cells in S phase at time zero. This method has been used to measure generation time and length of S phase of three kinds of haemopoietic progenitor cells: mouse granulocyte‐macrophage CFU, human T lymphocyte CFU and CFU from regenerating mouse spleens. This method should be applicable to any normal or neoplastic clonogenic cell populations and the latter could be either of haematological or of solid tumour origin.
Potential Pitfalls of [3H]Thymidine Techniques to Measure Cell Proliferation
Authors: Maurer H. R.
Published: May 2008

Pitfalls and artifacts in the use of [3H]thymidine in the measurement of cell proliferation kinetics in vitro and in vivo are reviewed. These pitfalls are of particular significance for the study of inhibitors of cell proliferation including chalones.
REGENERATION OF UTERINE EPITHELIUM AFTER EXPERIMENTAL ABLATION IN THE RAT
Authors: Leroy F. , Lejeune B. , Galand P.
Published: May 2008

Regeneration of the uterine luminal epithelium was studied after its mechanical removal in progesterone‐primed rats, leaving one control horn intact. Pulse labelling with [3H]TdR during regeneration, showed a rapid peak of labelling index in remaining glands. A differentiated and highly labelled luminal epithelium reappeared at 34 hr, thereafter showing a rapidly declining LI. After initial depletion, the glandular cell population size was restored within 64 hr, whereas luminal epithelium cell numbers became stabilized at about half normal level. Grain counts after prelabelling showed more rapid dilution in gland cells of stripped uterine horns, indicating accelerated cycling of previously dividing cells. Thymidine labelling indices also showed that, after removal of the epithelium, almost all gland cells became rapidly committed to divide. On average, less than two cell cycles were necessary to restore stable glandular and epithelial population sizes. Numbers of labelled cells were also drastically increased in myometrium and serosa of treated horns. This suggests a non‐specific mechanism for stimulation of mitotic activity after ablation of epithelium.
Post‐Irradiation Thymocyte Regeneration After Bone Marrow Transplantation Ii. Physical Characteristics of Thymocyte Progenitor Cells
Authors: Boersma W. J. A. , Daculsi R. , van der Westen G.
Published: May 2008

Bone marrow cells were separated according to buoyant density, velocity sedimentation and cell surface charge. Fractionated (C3H × AKR)F1 bone marrow cells were transplanted into lethally‐irradiated C3H recipients. In all fractions, the CFUs content and the capacity to restore the thymus cell population were determined. For all the physical parameters tested, thymocyte progenitor cells show the same distribution as CFUs. the relationship between number of thymocyte progenitor cells and number of CFUs is dependent on density. Bone marrow progenitors of PHA responsive cells are of low buoyant density and show a distribution which resembles the distribution of the progenitors of Thy 1 positive cells. After transplantation of large numbers of bone marrow cells into irradiated mice, no significant change in the CFUs content of the thymus was observed.
EVIDENCE OF RAPID AND SLOW PROGRESSION OF CELLS THROUGH G2 PHASE IN MOUSE EPIDERMIS: A COMPARISON BETWEEN PHASE DURATIONS MEASURED BY DIFFERENT METHODS
Authors: Clausen O. P. F. , Thorud E. , Aarnæs E.
Published: May 2008

Percentage labelled mitosis (PLM) measurements were initiated at four different times during a 24‐hr period and continued for 24 hr in hairless mouse epidermis. Estimates of G2 and S phase durations (mean TG2 and mean TS) were calculated. A significant number of labelled mitoses (10–20%) was seen after 30 min in all four PLM measurements and the estimated mean TG2 varied from 1.4 to 2.5 hr and was in agreement with values from PLM measurements in other epithelial tissues. These mean TG2 values were much shorter than expected from [3H]TdR double labelling experiments and from a multiparameter cell kinetic study in hairless mouse epidermis and did not reflect the circadian variations seen in these studies. the differences in estimates of phase durations can be explained by postulating two G2 cell populations; one with a rapid and another with a slow rate of cell cycle progression. the cells with the higher rate are mainly registered by the PLM method, whereas those with the lower rate largely escape detection by this method. TG2 estimates from PLM measurements in mouse epidermis therefore do not reflect the phase duration of the entire G2 population. It is also concluded that circadian variations in TS can not be accurately registered by the PLM method.
ANALYSIS OF THE VARIABILITY IN CLEAVAGE TIMES AND DEMONSTRATION OF A MITOTIC GRADIENT DURING THE CLEAVAGE STAGES OF NOTHOBRANCHIUS GUENTHERI
Authors: Van Haarlem R. , Van Wijk R. , Fikkert A. H. M.
Published: May 2008

Living embryos of the annual cyprinodont fish Nothobranchius guentheri were observed under the microscope. Detailed records were made of the time of cell division, disappearance of the nucleus and of the position of each cell within the blastoderm up to and including the sixth cleavage. Combination of these data revealed the presence of a mitotic gradient, a cell division gradient and a gradient of cell cycle duration in the 8‐cell, 16‐cell and 32‐cell stage. Comparison of the variabilities in the duration of the interphase and mitosis reveals that differences between sister cell intercleavage times in the 8‐, 16‐ and 32‐cell stage are, for the most part, due to the variability in the duration of the mitotic process. It is concluded that the DNA‐division cycle is composed of at least two parallel series of events. We found the random transition model of cell cycle control, originally based on the analysis of intermitotic times of mammalian cells in tissue culture, helpful also in analysing intercleavage time variability in embryonic cells.
Clonal Growth of Leukaemic Cells In Vitro
Authors: Preisler H. D. , Epstein J.
Published: May 2008

Human leukaemic cell specimens were obtained from patients and directly plated into soft agar (t= 0) or cultured for 1 week in liquid phase and then plated in soft agar. Growth for 1 week in liquid phase allowed the clonal growth in agar of leukaemic specimens which were unable to clone at t= 0. Clonal growth after liquid culture consisted of the usual leukaemic type of cluster‐colonies, growth of a new type of ‘syncytial’ cell colony or a mixture of colony types. In addition, marrow from a patient with acute lymphocytic leukaemia produced normal‐appearing colonies after 1 week of growth in liquid phase. These studies suggest a similarity in the growth requirements of some leukaemic cells and normal CFUd cells.
The Relationship of G0 to the Cell Cycle of Haemopoietic Spleen Colony‐Forming Cells
Authors: Lord B. I.
Published: May 2008

Normal haemopoietic stem cells, defined here as spleen colony‐forming units (CFUs), are slowly proliferating and are generally considered to spend most of their time in the non‐proliferative G0‐state. A series of experiments using various combinations of the stem cell proliferation inhibitor (NBME‐IV) and stimulator (RBME‐III) together with vinblastine as a mitotic blocking agent was designed to determine the location of the G0‐state relative to the cell cycle of the CFUs.

From a knowledge of the effects of these agents, the expected results from three different G0‐cell cycle models were charted and compared with the observed proliferative behaviour of the CFUs following these treatments. It was concluded that the out‐of‐cycle G0‐state is located at the end of the G1‐phase of the cycle, so that on receiving a stimulatory signal, the CFUs can rapidly enter the DNA‐synthesis phase.
Cytophotometric Evidence of Non‐S‐Phase Extra‐Dna In Human Neuronal Nuclei
Authors: Böhm N. , Kröner Bärbel , Kaiser Evelyn
Published: May 2008

After Feulgen staining with acriflavine‐Schiff, the DNA content of glial and neuronal nuclei from various sites of the human CNS (pre‐ and post‐central gyrus, cerebellar cortex and spinal cord) were determined by fluorescence cytophotometry. the specimens were obtained from twelve adult human autopsy cases. Glial cell nuclei always revealed a biomodal DNA distribution pattern with a large 2c and a smaller 4c peak. the 4c peak was most prominent in the cerebellum. A few 8c glial nuclei were found.

Neuronal cell nuclei disclosed unimodal DNA histograms with hyperdiploid means in the range 2.2–2.5c (1.8–2.9c for the individual populations). Tetraploid 4c DNA values were not observed, neither in Purkinje cells, nor in pyramidal cells. In eleven out of a total of forty‐four slides the higher DNA means of neuronal nuclei were found to be statistically significant (P < 0.05) when compared with a population of 2c hepatocytes on the same slide.

The results indicate the existence of some ‘extra DNA’ in human neuronal cell nuclei, the biological significance of which has still to be elucidated. It is however, suggested that it may play an important role in the functional activity of the CNS.
A Repopulation Assay For B and T Lymphocyte Stem Cells Employing Radiation Chimaeras
Authors: Hunt S. V. , Fowler M. H.
Published: May 2008

The repopulation of the peripheral lymphoid compartment of lethally‐irradiated rats reconstituted with lymphopoietic stem cells was studied. Cell lineages were traced by using genetic markers of cell surface molecules: immunoglobulin allotype for B lymphocytes and peripheral T cell alloantigen for T lymphocytes. Provided the markers had been bred on to a genetic background congenic with the hosts, they conferred neither an advantage nor disadvantage in competition with unmarked cells. the degree of chimaerism measured the lymphopoietic activity of the restorative inoculum. the most potent activity was found in foetal liver and spleen; next was infant spleen and bone marrow; then young adult bone marrow. Peripheral lymphoid tissues showed very little activity and thymus cells were inert. This tissue distribution, the stability of the chimaerism and the substantial expansion of numbers from the injected cells all point to the assay measuring an early stem cell.

The overlap of subpopulations of lymphocytes in the rat thoracic duct was studied. A method for the conjugation of fluorescein to antibodies while they are attached to immuno‐adsorbent affinity columns is also described.
KINETICS OF TISSUE PROLIFERATION IN COLORECTAL MUCOSA DURING POST‐NATAL GROWTH
Authors: Maskens A. P. , Dujardin‐Loits Rose‐Marie
Published: May 2008

The main developmental event in the colorectal mucosa during post‐natal growth is a dramatic increase in the number of crypts of Lieberkühn, resulting from a longitudinal fission of pre‐existing crypts. In the present study, the kinetic aspects of this process have been analysed, using extensive gland and cell counts involving the entire colon and rectum of 24 male BD IX rats distributed into four age groups.

The number of crypts was found to rise from an average 4652 to 423,800 between birth and adulthood; the corresponding ratios of bifurcating glands were 13.55 and 0.67%, respectively. Crypt production attained its maximum 18 days after birth with an hourly increment of 519 units. the time spent by replicating glands in the bifurcating stage (‘fission time’) averaged 6.9–10.5 hr.

The mean number of epithelial cells per crypt rose from 249 in 4‐day old rats to 635 in adults. the estimated total number of epithelial cells in the colon and rectum was one million in newborns and 248 million in adults. the increment in cell number peaked 3 weeks after birth with a value of 310,000/hr. During the first few days after birth, all cells produced in the epithelium were retained. Cell loss thereafter rapidly progressed, reaching 70% of the cell production in 3‐week old animals.
Polyploidy In the Murine Colonic Pericryptal Fibroblast Sheath
Authors: Neal J. V. , Potten C. S.
Published: May 2008

The cause of the apparently paradoxical occurrence of relatively high levels of labelling and low levels of mitotic activity in the pericryptal fibroblast sheath (PCFS) was investigated. Analysis of the distribution of grain densities over epithelial cells and the PCFS in the colon demonstrated that, although the former had a unimodal peak, the PCFS had a multi‐peak distribution. the PCFS nuclei with the higher grain densities gradually disappeared with time, due not to proliferation but to lateral migration into the lamina propria. Photodensitometric analysis confirmed the existence of polyploid cells in the colonic PCFS, but not in the epithelium.
EFFECTS OF ENVIRONMENTAL TEMPERATURE ON HAEMOPOIETIC STEM CELLS IN THE TAILS OF MICE
Authors: Littleton R. J. , Zebro T. , Wright E. A.
Published: May 2008

Using the endogenous spleen colony assay method of Till & McCulloch (1963), the numbers of haemopoietic stem cells present in the bone marrow in the tails of mice were estimated under different environmental temperatures. Compared to animals kept at 22–26°C, mice transferred to and kept at 36.5°C showed a doubling of colony‐forming units in the tail in 1–4 weeks. Exposing them to 8°C caused a significant depopulation to approximately one‐third in 3–4 weeks. By transferring the mice from one temperature extreme to another these changes could be reversed. Tail marrow depleted of viable stem cells by X‐irradiation was repopulated within approximately 3 weeks in animals kept at room temperature or above but this process was inhibited in the cold.
Rat Serum Factors Inhibiting the G1‐S Transition In Hepatocytes
Authors: Nadal C. , Le Rumeur E. , Boffa G. A.
Published: May 2008

An attempt was made to detect the serum factors inhibiting the G1‐S transition in synchronized, baby rat hepatocytes. In untreated adult rat serum, this inhibitory activity was always linked to high molecular weight (HMW) compounds. Incubation of serum with trypsin or chymotrypsin resulted in the formation of a low molecular weight (LMW) G1‐S inhibitory factor. the same result was obtained with fractions from adult rat liver but not with kidney or spleen fractions. Separation of the LMW factor by ultrafiltration increased its specific activity by about 103. the active period in the cell cycle of both the LMW and HMW factors was the same: the late G1 phase. However, the activity of the LMW factor was not blocked by the Kunitz factor. an enzymatic transformation of the HMW factor might be induced by liver cell membrane‐bound proteases and constitute a mechanism regulating hepatocyte proliferation.
Dna Synthesis and Cell Generation Pattern of Chronic Lymphatic Leukaemia Lymphocytes Stimulated By Phytohaemagglutinin
Authors: Matera L. , Cordero A. , Piazza A. , Giovinazzo B. , Pegoraro L.
Published: May 2008

A detailed analysis of the cell recruitment and of the cell generation pattern of normal lymphocytes and chronic lymphatic leukaemia (CLL) lymphocytes, simulated by phytohaemagglutinin (PHA), was performed by the bromodi‐oxyuridine (BUdR) Hoechst technique.

It was found that in normal cultures the majority of cells divide two or three times, producing an early peak of DNA synthesis, while only a few cells grow exponentially and pass through many rounds of replication. On the contrary, the majority of CLL responsive cells grow exponentially, producing a delayed peak of DNA synthesis, while cells which divide only two or three times are scarce or absent. No difference in the minimal cell cycle length of the normal and the CLL exponentially growing population was found. In addition, a cell population recruited into cycle for the first time 5–6 days following PHA stimulation was observed in normal cultures but not in CLL cultures.
Cell Kinetic Characteristics In Different Parts of Multicellular Spheroids of Human Origin
Authors: Wibe E. , Lindmo T. , Kaalhus O.
Published: May 2008

The growth fraction, the cell cycle time, and the duration of the individual cell cycle phases were determined as a function of distance from the surface of multicellular spheroids of the human cell line NHIK 3025. the techniques employed were percentage of labelled mitoses and labelling index measurements after autoradiography and flow cytometric measurements of DNA histograms. to separate cell populations from the different parts of the spheroid, fractionated trypsinization was employed.

The results were compared with corresponding values in NHIK 3025 cell populations grown as monolayer cultures. While practically all cells in exponentially growing monolayer populations are proliferating, the growth fraction was between 0.6 and 0.7 in the outer parts of the spheroid. the inner region was mainly occupied by a necrotic mass. the proliferating fraction of the recognizable cells in the inner region was slightly below 0.5. the mean cell cycle time of NHIK 3025 cells in monolayer culture is 18 hr. the mean cell cycle time of proliferating cells in the periphery of the spheroid was 30 hr, compared to 41 hr in the inner region (150 μm from the spheroid surface). All phases of the cell cycle were prolonged compared to populations of exponentially growing monolayer cells. Within each part of the spheroid the distribution of cell cycle times was considerably broadened compared with monolayer populations.
Analysis of the effect of hydroxyurea on stem cell (CFU‐s) kinetics
Authors: Neĉas E. , Hauser F.
Published: May 2008

Abstract. Hydroxyurea induces profound changes in the pluripotential haemopoietic stem cell (CFU‐s) kinetics. The main feature of these changes is a synchronous entry of resting Go CFU‐s into the cell cycle. The analysis of the passage of the CFU‐s cohort through the cell cycle has been largely based on the examination of the fraction of CFU‐s which synthesize DNA in the S phase of the cell cycle. This analysis has, however, been hampered by the fact that both the sensitivity of the S phase CFU‐s to hydroxyurea and their sensitivity in the [3H] thymidine suicide technique vary as the cells pass through the S phase. Methods which overcome these difficulties have been used in the experiments presented in this paper.

It was demonstrated that hydroxyurea kills only about 80% of the S phase CFU‐s. The sensitivity to hydroxyurea gradually decreases as the cells approach the middle part of the S phase and increases again as the cells enter the late portions of the S phase.

The degree of CFU‐s synchrony at the point of entry into and exit from, the S phase has been established. Mathematical analysis of the available data suggests that CFU‐s pass through the S phase with a mean transit time of 4–79 hr (standard deviation, 1.45 hr).

Hydroxyurea, administered in vivo, blocks CFU‐s in the late G1 phase. The duration of this G1‐S block, induced by a dose of 1000 mg of hydroxyurea per kg body weight, is approximately 2 hr. The CFU‐s in the middle of the S phase, which survive hydroxyurea administration, are also blocked in their passage through the S phase. These cells, however, seem to finish the S phase with a delay of approximately 2 hr.
Cell kinetics of pulmonary alveolar macrophages in the mouse
Authors: Coggle J. E. , Tarling J. D.
Published: May 2008

Abstract. This study of pulmonary alveolar macrophages (PAMs) involves two techniques, one following the migration of a cohort of labelled PAMs from the lung and the other involves the use of a continuous labelling method with [3H]TdR. In both studies, strikingly similar, probably biphasic curves are obtained that can be interpreted as indicating the existence of two proliferating cell populations with turnover times of ˜10 days and ˜35 days. It is suggested that one of these compartments is an intra‐alveolar PAM population whilst the other probably represents a precursor population. It is also possible to interpret the data as indicating a single, and probably solely intra‐alveolar, PAM population with a very skewed distribution of cell cycle times.
The regulation of bone marrow‐derived mononuclear phagocyte differentiation and mobilization in syngeneic and allogeneic YAC‐lymphoma‐bearing mice
Authors: Bursuker I. , Goldman R.
Published: May 2008

Abstract. YAC‐lymphoma inoculation (ip) into syngeneic A/J mice results in a massive in situ proliferation of the lymphoma cells, with non‐significant increases in the peritoneal macrophage population, and also in a remarkable and progressive increase in the bone marrow precursor cells forming both macrophage and fibroblastoid colonies in vitro. In the allogeneic situation (BALB/c mice), YAC‐lymphoma cells proliferate to a limited extent before tumour regression. These processes (i.e. proliferation and regression) were accompanied by a progressive increase in the peritoneal macrophage population, which declined to normal after tumour regression. Macrophages accumulating at the regression stage exhibited in vitro cytolytic activity towards YAC‐lymphoma cells and cytostatic activity towards unrelated cells. No correlation was observed between the limited asynchronous increase in the bone marrow level of precursor cells for in vitro differentiating macrophage and fibroblastoid colonies, on one hand, and macrophage accumulation at the tumour site in BALB/c mice on the other. Conditioned media from in vitro proliferating YAC‐lymphoma cells exhibited high colony‐stimulating activity for macrophage colony formation in vitro. Bone marrow cells taken from YAC‐lymphoma inoculated A/J mice expressed potent tumorogenic potential at early stages after tumour inoculation. At day 2 after tumour inoculation the bone marrow cells were already tumorogenic and concomitantly expressed augmented levels of macrophage and fibroblastoid colony‐forming capacity.

The results indicate an inter‐relationship between tumour growth and mononuclear phagocyte differentiation and proliferation.
A re‐evaluation of the changes in proliferation in human fibroblasts during ageing in vitro
Authors: Macieira‐Coelho A. , Taboury F.
Published: May 2008

Abstract. Previously published studies concerning the proliferative changes, during ageing in vitro, of human embryonic fibroblasts, have been reappraised. The data suggest that the changes occur through shifts in a whole spectrum of cells between two extremes: complete inhibition and a normal division cycle. Reversion from the non‐dividing to the dividing state becomes increasingly difficult and random. Ageing is the result of a long chain of events that hinder the transit of cells through the division cycle, mainly through interference with the G1 but also with the G2 period. Some metabolic events at the very end of the lifespan could support the terminal differentiation hypothesis.
Proliferation kinetics of endothelial and tumour cells in three mouse mammary carcinomas
Authors: Hirst D. G. , Denekamp J. , Hobson B.
Published: May 2008

Abstract. An autoradiographic study of three corded mouse tumours is reported. The proliferation characteristics of both tumour cells and endothelial cells were studied. The doubling time of these three tumours differed by a factor of 2.6 but there was only a small difference in the intermitotic time. All three tumours showed a very high cell loss factor (˜0.80) and the differences in growth rate resulted mainly from differences in the growth fraction.

The endothelial cell proliferation rates differed markedly in the three tumours, with labelling indices ranging from 18% in the faster tumours to 4.5% in the slowest. The potential doubling times for endothelium, calculated from these values, were much slower than the tumour cell cycle time or the tumour potential doubling time, but were two to four times faster than the volume doubling time of the tumour.

It appears likely that the endothelial proliferation rate influences the growth fraction, but similar high cell loss factors can occur in tumours with a four‐fold difference in endothelial cell production rates. Inadequate branching of blood vessels seems likely to be at least as important as inadequate production of endothelial cells. It is not possible to determine whether slow tumour cell production evokes a slower endothelial growth or vice versa.
Cell population kinetics of thyroid follicular cells in infant rats
Authors: Christov‐Tzelkov K. , Graschev G.
Published: May 2008

Abstract. T cell population kinetics of thyroid follicular cells in rats were studied by means of autoradiography and a statmokinetic technique. During the first fortnight after birth no significant changes in the mitotic index (MI) and labelling index (LI) were found. In the next 2 weeks a constant decrease in the number of proliferating cells occurs. In 10‐day old animals 40% of the follicular cells were in the cell cycle (GF); 3.25 ± 0.77 (SEM) % in the S phase and 0.18 ± 0.04% in mitoses (MI). Day–night changes in the LI and mitotic rate (MR) indicated a peak value at 13.30 hours with a lowest value at 22.30 hours. The mean LI and MR averaged over the whole 24 hr were 3.1 ± 0.1% and 122.2 ± 18.1%, respectively. In 10‐day old animals, using the fraction of labelled mitoses (FLM) method the median cell cycle time (TC) was 79 hr and the phase durations were TG1—64.6 hr, Ts—8.2 hr and TG2—5.1 hr. The decrease in the number of proliferating cells with the age of the animals is considered to be a result of both cell cycle prolongation and in growth fraction reduction.
The stimulation of bone marrow granulopoiesis of normal CBA mice in vitro and in vivo by serum obtained from leucophoretic rats
Authors: Jovčić G. S. , Stojanović N. N. , Hajduković S. I. , Petrović N. V.
Published: May 2008

Abstract. The effect of leucophoretic serum (LS), obtained from rats with polyvinylpyrrolidone (PVP)‐induced inflammation, on granulopoiesis in the bone marrow of normal CBA mice was studied. The following test systems were used: short term cultures (4 hr), diffusion chambers (8, 24, 48 and 72 hr) and in vivo assays (12, 24 and 48 hr). The results indicate that LS stimulates the proliferations of granulocytic cells by increasing the number of proliferative granulocytes in mitosis, as well as increasing the total number of proliferative granulocytes. LS did not appear to effect monocytes and other cell lines. It is concluded that a factor present in LS specifically stimulates the proliferation of granulocytic cells, both in vitro and in vivo.
Effect of low‐dose whole‐body irradiation on granulopoietic progenitor cell subpopulations: implications for CFUc release
Authors: Gerhartz H. H. , Nothdurft W. , Fliedner T. M.
Published: May 2008

Abstract. The reaction of the granulopoietic system to whole body irradiation with 0.80 and 1.60 Gy was studied in dogs by means of colony formation assays in combination with velocity sedimentation and tritiated thymidine cytocidal techniques. Depression of circulating CFUc was associated with a marked shift in the size distribution of granulopoietic progenitors in the bone marrow. This effect lasted much longer in those animals receiving the lower X‐ray dose. We conclude that circulating CFUc are not a random proportion of the bone marrow but a subpopulation of cells which are smaller in size. These cells are in an equilibrium with the larger marrow CFUc, which is very sensitive to perturbations.
Growth pattern of the human promyelocytic leukaemia cell line HL60
Authors: Foa P. , Maiolo A. T. , Lombardi L. , Toivonen H. , Rytömaa T. , Polli E. E.
Published: May 2008

Abstract. In order to characterize the growth pattern of the human promyelocytic leukaemia cell line HL60, its kinetic parameters were studied. The doubling time was calculated from serial cell counts, the duration of the various cell cycle phases from the analysis of the labelled mitoses curve, and quiescent population from continuous labelling experiments. Proliferation in culture was exponential up to a saturation density of about 3.0 × 106 cells/ml, with a doubling time of 34.0 hr. The cell cycle duration was 24.3 ± 4.1 hr (SD), and that of the cell cycle phases was: G1, 3.8 ± 2.2 hr; S, 15.1 ± 3 hr; and G2, 5.4 ± 1.2 hr. The growth fraction was 0.85, and cell loss was restricted to the quiescent cells. The HL60 cell line, with fully characterized kinetics, provides a useful tool for the in vitro study of substances which may affect human leukaemic myelopoietic proliferation.
A comparative investigation of the antimitotic action of 2‐mercaptoethanol and colcemid on V‐79 Chinese hamster cells
Authors: Speit G. , Speit Dorothee , Vogel W.
Published: May 2008

Abstract. The current study was performed to characterize the antimitotic action of 2‐mercaptoethanol (MET) on mammalian cells.

At concentrations of 2.5 × 10‐2 M, MET arrests V‐79 Chinese hamster cells in metaphase. Smaller concentrations (from 5 × 10‐3 M) only produce a mitotic block after several hours, only arresting those mitoses which have gone through one cell cycle in the presence of MET. The accumulation of mitoses by MET is smaller in comparison with colcemid, explained by an effect reducing the number of cells which enter mitosis. In contrast to colcemid, MET‐concentrations which do not lead to a mitotic block cause a delay in proliferation. It was shown, by means of the BUdR‐labelling method that cells in the presence of colcemid concentrations which arrest mitosis again enter interphase and become polyploid, whereas MET leads to an irreversible arrest of mitosis and does not produce polyploidy in V‐79 cells.
A comparative kinetic analysis of proliferation in vitro of Con‐A‐treated splenocytes and syngeneic leukaemia cells
Authors: Olivotto M. , Boddi V. , Sbarba P. Dello , Arcangeli Annarosa
Published: May 2008

Abstract. The growth kinetics of Con‐A‐treated mouse splenocytes and syngeneic leukaemia cells cultured in vitro were compared with respect to (i) the total cell number, (ii) the rate of [14C]thymidine incorporation (measured by pulse‐labelling the cells at various times of incubation), and (iii) the labelling index of the cell populations. By correlating the thymidine incorporation, labelling index and cell number data, it has been established that, for both types of cells, the rate of [14C]thymidine incorporation is directly proportional to the number of cells synthesizing DNA. A new approach to cytokinetic analysis has been developed, showing that important information can be obtained by determining the cumulative kinetics of [14C]thymidine incorporation. The latter has been calculated by integrating the area underneath the time course of the rate of thymidine incorporation, and was directly proportional to the overall growth of both leukaemia cells and Con‐A‐stimulated splenocytes. Based on this proportionality, an estimate of the average duration of the S phase for both types of cells was calculated, suggesting that normal and neoplastic blasts maintain this parameter at a constant value (7.6 and 5.9 hr, respectively) throughout different stages of growth. The percentage of Con‐A‐responsive cells within the initial splenocyte population and their overall proliferation in vitro have been determined by a procedure which measures the cumulative kinetics of thymidine incorporation and the kinetics of cell total number in the presence or in the absence of the lectin, as well as in the presence of Con‐A plus colcemid. A minor fraction (11%) of the initial splenocytes is recruited into cycle by Con‐A, proliferating with similar kinetics to that of leukaemia cells in the same conditions. The great majority of the initial splenocyte population is unaffected by Con‐A, decaying exponentially throughout the incubation with the same half‐life (28 hr), both in the presence or in the absence of the lectin.
Acute lethal graft‐versus‐host disease stimulates cellular proliferation in the adult rat liver
Authors: Klein R. M. , Jr J. Clancy , Stuart S.
Published: May 2008

Abstract. The present investigation was designed to analyse the effects of acute lethal graft‐versus‐host disease (GVHD) in adult (DA x LEW)F1 rats on cellular proliferation within the liver. The influence of the host thymus on GVHD‐induced proliferation was also assessed. From 1–28 days after initiation of GVHD [3H]thymidine ([3H]‐TdR) was injected i.v. and rats were killed one hour later. Percentage labelled cells (LI) of periportal infiltrating cells (PIC), hepatocytes (H), and sinusoidal lining cells (SC) were counted. Mean values for control rats were 0.3 ± 0.1% (H), 0.4 ± 0.1% (SC) and 0.2 ± 0.1% (PIC). GVHD rats demonstrated a significant increase in LI of PIC (days 1–21), SC (days 2–17) and H (days 2–17). Most labelled cells in PIC were large lymphocytes. Peak LI values were 7.0 ± 1.0% PIC (day 17), 6.8 ± 0.9% SC (day 17), and 5.2 ± 0.9% H (day 7), with all cellular compartments returning to near normal LI values by day 28. Stimulation of cellular proliferation occurred in all three liver cell compartments in neonatally thymectomized (TXM) rats. The intensity of GVHD‐induced cell proliferation was significantly decreased at day 7 in all compartments and PIC was dramatically decreased at day 21 in TXM‐GVHD rats as compared to non‐TXM‐GVHD rats. It is hypothesized that the general stimulation of hepatocyte cell proliferation in GVHD is related to the secretion of lymphokines by primarily donor and secondarily host T cells in the periportal infiltrate.
Origin and Kinetics of Resident Tissue Macrophages
Authors: Parwaresch M. R. , Wacker H.‐H.
Published: May 2008

Abstract To elucidate the origin and renewal kinetics of peritoneal macrophages, as a typical example of the mononuclear phagocytic system, syngeneic rats were treated with tritiated thymidine [3H]TdR and leucocytes were transferred to unlabelled recipients over a bilateral arteriovenous shunt. Labelled and unlabelled monocytes were evenly distributed in both animals as shown by autoradiography. It was ascertained that no ‘autoradiographically’ detectable reutilization of label occurred and that transferred cells showed undisturbed kinetics. the results imply: 1 resident peritoneal macrophages derive from blood monocytes; 2 peritoneal macrophages represent a homogeneous population in respect to their cellular origin; 3 blood monocytes as a myelogeneous cell line do not represent a generative end cell. They migrate into the tissue (peritoneal cavity) and differentiate into resident macrophages, undergoing on average one mitosis per cell during a period of approximately 7 days. 4 resident peritoneal macrophages are derived 50% from blood monocytes and 50% from division in situ; and 5 under steady‐state conditions the renewal rate amounts to 0. 18%/h, which yields a half‐life time of 16 days and a renewal time of 23 days.
Some Mechanisms of Disturbances and Recovery of T‐Lymphocyte Migratory Properties In Irradiated Mice
Authors: Anokhin George N. , Yarilin Alexander A.
Published: May 2008

Abstract Migration of 51Cr‐labelled T cells from irradiated mice into lymph nodes of syngeneic unirradiated recipients decreased in a dose‐dependent fashion. Influx of labelled T cells between 4 and 24 hr after injection (secondary migration) is more radiosensitive than lymph‐node migration of T cells in the first 4 hr (primary migration). Treatment of T cells from irradiated mice in vitro with Con A or with trypsin does not enhance radiation‐induced alteration of their migratory properties, but irradiation enhances the effects of Con A and trypsin on T‐cell migration. Recovery of primary migration of irradiated T cells is completed 3 months after irradiation; it is probably caused by T‐cell renewal. the defect of T‐cell secondary migration is more stable: it remains 6 months after irradiation in a dose of 4 Gy. Post‐irradiation defects of the T‐cell differentiation process as a cause of long‐lasting alteration of T‐cell secondary migration are discussed.
Amiloride and Other Blockers of Electrolyte Flux As Inhibitors of Progesterone‐Stimulated Meiotic Maturation In Xenopus Oocytes
Authors: Cameron Ivan L. , Lum Jean B. , Cragoe Edward J.
Published: May 2008

ABSTRACT Amiloride and seven of its analogues, as well as seven substances of other structural types, all of which control electrolyte transport, were tested for their effectiveness for inhibiting the progesterone‐stimulated meiotic maturation cycle of oocytes from the amphibian Xenopus luevis. Data were also collected on the ability of the oocytes to recover from the drug's inhibitory effect and on the toxicity of each drug. the data revealed that up to a 14‐fold difference exists in the inhibitory concentration 50% between substances, that recovery from the drug's inhibitory effect ranged from non‐reversible to almost complete reversibility and that toxicity, as measured by failure to exclude trypan blue, ranged from 0 to 57%. In some, but not all cases, the failure to recover from the drug's inhibitory effects could be correlated to the drug's toxic effects. Amiloride which has been shown to be a reversible inhibitor of cell proliferation in rapidly dividing mammalian cell populations has similar properties on the oocyte maturation division cycle of Xenopus.
Method For Binary Classification and Risk Assessment of Individuals With Familial Polyposis Based On [3H]Tdr Labelling of Epithelial Cells In Colonic Crypts
Authors: Lipkin Martin
Published: May 2008

Abstract An analysis has been developed to improve the quantitation of abnormal patterns of tritiated thymidine ([3H]TdR) labelling of colonic epithelial cells, in biopsy specimens removed from human subjects at varying degrees of risk for colon cancer. After pulse incubation of specimens of colonic mucosa with [3H]TdR, each subject's microautoradiographic epithelial cell labelling distribution was segregated into eleven compartments over entire colonic crypts. the findings of each subject were then analysed to determine their relative degree of similarity to the findings for two reference populations of interest, i.e. a high‐risk and a low‐risk population; the individual was then classified as being closer to one or the other of the reference populations. the analysis developed is based upon a comparison of multinomial probabilities for the distributions of the labelled cells within the crypts, and permits the routine categorization of uneven distributions of labelled cells. For each subject, certain linear scores, a prognostic index based on them, and a related presumptive risk, were calculated. the sensitivity with which individuals known to be symptomatic for polyposis, and the specificity with which individuals known to be at lower risk were determined, were 73 and 93% respectively. the results suggest that this method of distinguishing among integer distributions of [3H]TdR‐ labelled cells in biopsies of colonic mucosa, may provide a useful basis for identifying individuals with familial polyposis, by separating their labelling patterns from those of low‐risk subjects.
Cell Synchrony Techniques. II. Analysis of Cell Progression Data
Authors: White R. Allen , Grdina David J. , Meistrich Marvin L. , Meyn Raymond E. , Johnson Tod S.
Published: May 2008

Abstract CHO cells which have been sorted by mitotic detachment, centrifugal elutriation and fluorescence activated cell sorting have been followed for up to 14 hr by flow cytometry to examine their progression characteristics. Mathematical modelling techniques were used to provide quantitative estimates of the cell‐cycle parameters. Mitotic detachment gives an 11.2‐hr cycle time with mean transit times TG1, Ts and TG2M equal to 3.2, 5.6 and 2.4 respectively. Cells prepared by central elutriation in an early G1 state have a 14‐hr cycle time with TG1, Ts and TG2M of 5.7, 6.0 and 2.3 hr. Populations prepared by centrifugal elutriation enriched in early S and late S and G2M have transit times of 2.7, 5.9 and 1.6 hr and 4.9, 6.7 and 2.1 hr with cycle times of 11.2 and 13.2 hr respectively. Cell sorting for a G1 population gives transit times of 9.8, 8.0 and 3.6 for an overall 21.4‐hr cycle time.
Cells Forming Spleen Colonies At 7 Or 11 Days After Injection Have Different Proliferation Rates
Authors: Chertkov J. L. , Drize Nina J.
Published: May 2008

Abstract In the early periods (7–9 days) after haemopoietic cell injection, colonies produced by CFU‐s and by their progeny are identified in the spleen, while at later periods (11 days after injection) only spleen nodules produced by CFU‐s persist. the increase in the suicide values of CFU‐s after sublethal (2 Gy) irradiation of mice is associated with a higher proliferation rate of precursors of transitory spleen colonies, but not of CFU‐s, as measured by different suicide techniques. During the log‐phase of cell growth in a lethally irradiated recipient, the injected CFU‐s and CFU‐tr proliferate at a higher rate. Active proliferation of CFU‐s and CFU‐tr has been demonstrated in long‐term bone‐marrow cultures by the hydroxyurea in‐vitro suicide assay. CFU‐tr may be the cause of artifactual effects during measurement of haemopoietic stem‐cell cycling by CFU‐s suicide methods.
Correlation Between the Rhythms of Blood Insulin Levels and the Stimulation of Spleen Lymphocytes By Concanavalin‐A In Mice
Authors: Prunet J. , Panijel J.
Published: May 2008

An ultradian rhythm of DNA synthesis and an in‐vitro response to Concanavalin‐A (Con‐A) stimulation has been found in splenocytes of DBA/2 male mice, living under conditions standardized for light‐synchronized periodicity. It was characterized by two peaks during the nycthemeral cycle. One of them was very sharp.

In spite of a constant mode of synchronization of the animals, there were seasonal variations of the rhythm. Such variations did not, however, affect the position of the sharp peak, which occurred always at the same hour.

The rhythm of incorporation of [3H]‐thymidine by splenocytes, whether or not stimulated by Con‐A, seemed correlated with that of blood insulin levels in mice. the possible effect of the physiological increase in blood insulin during the circadian cycle has been confirmed experimentally. Thus it seems probable that insulin would be one of the internal synchronizers.
Pluripotent Stem Cells Do Not Completely Maintain Normal Human Steady‐State Haemopoiesis
Authors: Dörmer P. , Ucci G.
Published: May 2008

Since the classical work on the regulation of canine erythropoiesis by Alpen & Cranmore (1959), it has been generally accepted that recognizable bone‐marrow cells are continuously replaced from sources of unrecognizable precursors. Although many features of pluripotent stem cells (PSC) and committed haemopoietic precursors have been determined, direct demonstration of a continuous influx, under normal steady‐state conditions, from PSC into the recognizable bone‐marrow cell compartments is still lacking. There is abundant evidence that PSC, in a number of species, including primates, resemble atypical or immature (‘transitional’) lumphocytes. By utilizing the technique of quantitative 14C‐autoradiography, we have measured the activities of DNA and protein synthesis in individual bone‐marrow cells of two healthy humans. A positive relationship was established between the protein synthesis rate and rate of movement through the cell cycle in all proliferative compartments. Lymphoid cells, considered to contain the fraction of PSC, were found in the lower range of this relationship. These low metabolic rates exclude fast growth as well as short cell‐cycle times. In view of the low frequency of the potential PSC in the human bone marrow, amounting to less than 2%, these cells cannot be considered to represent a source continuously supplying the pool of rapidly proliferating, recognizable blast cells in the bone marrow under steady‐state conditions. Some self‐maintenance of a subcompartment within the pool of recognizable normal bone‐marrow blast cells is therefore suggested.
Regulation of haemopoietic stem‐cell proliferation in mice carrying the Slj allele
Authors: Ploemacher R. E. , Nikkels P. G. J. , Molendijk W. J. , Brons N. H. C. , Brockbank K. G. M.
Published: May 2008

We investigated a haemopoietic stromal defect, in mice heterozygous for the Slj allele, during haemopoietic stress induced by treatment with bacterial lipopolysaccharides (LPS) or lethal total body irradiation (TBI) and bone‐marrow cell (BMC) reconstitution. Both treatments resulted in a comparable haemopoietic stem cell (CFU‐s) proliferation in Slj/+ and +/+ haemopoietic organs. There was no difference in committed haemopoietic progenitor cell (BFU‐e and CFU‐G/M) kinetics after TBI and +/+ bone‐marrow transplantation in Slj/+ and +/+ mice. the Slj/+ mice were deficient in their ability to support macroscopic spleen colony formation (65% of +/+ controls) as measured at 7 and 10 days after BMC transplantation. However, the Slj/+ spleen colonies contained the same number of BFU‐E and CFU‐G/M as colonies from +/+ spleens, while their CFU‐s content was increased. On day 10 post‐transplantation, the macroscopic ‘missing’ colonies could be detected at the microscopic level. These small colonies contained far fewer CFU‐s than the macroscopic detectable colonies. Analysis of CFU‐s proliferation‐inducing activities in control and post‐LPS sera revealed that Slj/+ mice are normal in their ability to produce and to respond to humoral stem‐cell regulators.

We postulate that Slj/+ mice have a normal number of splenic stromal ‘niches’ for colony formation. However, 35% of these niches is defective in its proliferative support.