bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes In Stem Cell Compartments In Mice After Hydroxyurea
Authors: Nečas E. , Poňka P. , Neuwirt J. 
Published: May 2008

ABSTRACTHydroxyurea injection kills only approximately 10% of CFU, which are in the S phase of the cell cycle. In mice given a single injection of hydroxyurea CFUs in the femur decreased only about 50% in 2–4 days after hydroxyurea, and then started to return to normal levels with an overshoot evident after the eighth day after hydroxyurea. CFUs in spleens of mice given a single injection of hydroxyurea show an evident overshoot as early as 3 days after the drug, reaching levels which are about 300% of normal. CFUs from blood disappear rapidly, but equally rapidly return to normal values followed by a significant overshoot. the radioresistance of mice increased up to 4 days after hydroxyurea.
Chalone Inhibition of Granulocyte Colony Growth In Agar: Kinetic Quantitation By Capillary Tube Scanning
Authors: Maurer H. R. , Henry R. , Maschler R. 
Published: May 2008

ABSTRACTMouse bone marrow cells were seeded into capillary tubes containing agar with colony stimulating factor. the development of myelomonocytic clusters and colonies was followed by daily tube scanning using their light scattering properties. Three kinetic scanning parameters were determined and the significance of different threshold settings was evaluated; viz. the number of signals, the mean signal height and the signal integrals. the inhibitory effect of two extracts with known granulocyte chalone activity which had been prepared from human peripheral leukocytes and rat bone marrow cells, was followed with the scanning method. A continuous reduction of clusters and colony formation and their growth throughout the incubation period was observed which suggested a sustained retardation of proliferation of both the stem cells committed for myelomono‐poiesis and their progeny.
Differential Radiation Response Amongst Proliferating Epithelial Cells
Authors: Potten C. S. , Al‐Barwari S. E. , Searle J. 
Published: May 2008

ABSTRACTTissue irradiation results in both reproductive and histologically evident cell death. the correlation between these is poor. Irrespective of dose and fraction sterilized, many cells behave as if unirradiated (cell cycle and maturation activity). the fraction of histologically observable dead cells is usually less than 0.1, with most in the intestine being positioned in the presumptive stem cell region. the data strongly suggest different epithelial sub‐populations with differing radioresponses. These may be the stem and differentiated proliferative cells.
ANALYSIS OF GROWTH OF TETRAPLOID NUCLEI IN ROOTS OF VICIA FABA
Authors: Bansal J. , Davidson D. 
Published: May 2008

ABSTRACTGrowth of nuclei of a marked population of cells was determined from G1 to prophase in roots of Vicia faba. the cells were marked by inducing them to become tetraploid by treatment with 0.002% colchicine for 1 hr. Variation in nuclear volume is large; it is established in early G1 and maintained through interphase and into prophase. One consequence of this variation is that there is considerable overlap between volumes of nuclei of different ages in the cell cycle; nuclear volume, we suggest, cannot be used as an accurate indicator of the age of the cell in its growth cycle. Nuclei exhibit considerable variation in their growth rate through the cell cycle. of the marked population of cells, about 65% had completed a cell cycle 14–15 hr after they were formed. These tetraploid nuclei have a cell cycle duration similar to that of fast cycling diploid cells of the same roots. Since they do complete a cell cycle, at least 65% of the nuclei studied must come from rapidly proliferating cells, showing that variability in nuclear volumes must be present in growing cells and cannot be attributed solely to the presence, in our samples, of non‐cycling cells.
A Stochastic Model For Cell Populations With Circadian Rhythms
Authors: Hopper J. L. , Brockwell P. J. 
Published: May 2008

ABSTRACTA mathematical model for cell kinetics, based on a random walk, is developed. the model allows variations with time of the rates of passage of proliferating cells through the four phases of the mitotic cycle. Circadian variations in the mitotic and labelling indices of the Syrian hamster cheek pouch epithelium have previously been observed, and the random walk model has been used to simulate this phenomenon. Assuming that all basal cells are proliferative and that these cells leave the basal layer randomly throughout the mitotic cycle to become differentiated cells, it was found that the experimentally observed circadian rhythms of the mitotic and labelling indices could be reproduced in the model by postulating a circadian rhythm in the rate of passage of cells through the G1 and S phases only. Moreover, the growth activity of cells in both the G1 and S phases appears to reach a peak during the dark hours of the light‐dark cycle, and to fall off rapidly in the early hours of daylight. the postulate of Møller, Larsen & Faber (1974) that injection of the animals with tritiated thymidine causes a shortening of the G2 phase duration has been qualitatively confirmed by using the random walk model to simulate the FLM and MI curves after injection with tritiated thymidine.
FAILURE TO FIND A HUMORAL FACTOR WHICH INFLUENCES THE COMPENSATORY RESPONSE AFTER RESECTION OF THE RAT SMALL BOWEL
Authors: Kirchner F. R. , Osborne J.W. 
Published: May 2008

ABSTRACTSmall bowel resection was performed in one parabiont of a parabiotic rat pair to determine whether there was a ‘humoral’ or other circulating factor present which could influence the compensatory response seen in the remainder of the small bowel. Following intestinal resection in one parabiont, there was an increase in DNA synthesis in the intestine of that member provided at least 40% of the small intestine was removed. the compensatory response seen in a resected animal was not observed in its parabiotic partner, even though an attempt was made to make the potentially responding animal more sensitive to the influence of any circulating ‘factors’ by resecting its intestine as well.The results obtained are in disagreement with the one closely related report in the literature; it is suggested that there is no good evidence for the existence of a resection‐induced circulating factor with the capability of crossing a vascular anastomosis and controlling proliferation of small intestinal epithelium.
Endogenous Thymic Factors Regulating Cell Proliferation and Analysis of Their Mechanism of Action
Authors: Blazsek I. , Gaál D. 
Published: May 2008

ABSTRACTEndogenous factors inhibiting the proliferation of T‐lymphocytes were investigated which may function as modulators of T‐lymphocyte production within the thymus. an extract from calf thymus (T4) enriched in lymphocyte chalone arrests rat thymocytes at the G1 S boundary and in the S phase of the cell cycle in short‐term cultures. It also inhibits the proliferative response of human peripheral blood lymphocytes to PHA‐P in a time‐dependent manner, as well as the spontaneous proliferation of in vitro cultured human chronic leukaemic lymphoblasts. This crude extract contains two active moities which can be isolated by molecular filtration on Sephadex G‐75 column.A species non‐specific, cell line selectivity inhibitory effect is characteristic of the high molecular weight fraction (mol. wt. > 40,000). This activity is resistant to moderate heat treatment and trypsin but is sensitive to mild alkaline hydrolysis and to RNase A digestion. About ten protein components and a toluidine blue positive substance can be detected by analytical polyacrylamide gel electrophoresis. the active inhibitor, a proposed protein‐RNA complex, might be identical with the chalone.The low molecular weight, non‐dialysable factor (T4–4) inhibits [3H]thymidine incorporation into acid insoluble DNA in a cell non‐specific manner. A possible relationship between the two activities is discussed.
Cell Proliferation In Emt6 Tumors Treated With Single Doses of X‐Rays Or Hydroxyurea. I. Experimental Results
Authors: Rockwell Sara , Frindel Emilia , Valleron A. J. , Tubiana M. 
Published: May 2008

ABSTRACTEMT6 mouse mammary tumors were treated in vivo with 5 mg/mouse of hydroxyurea (HU) or 300 rads of X‐rays. the proliferation of the tumor cells was followed for 28 hr after treatment. Changes in the 3H‐TdR labeling index, the mitotic index, the specific activity of the 3H‐TdR‐labeled DNA, and the proportion of suspended, clonogenic cells in the S phase of the cell cycle were examined and compared. Evidence was found for reassortment of the surviving cells in treated tumors into partially synchronous cohorts. the partial synchrony in the proliferation of the surviving cells was not accurately predicted by the changes in the labeling index and the mitotic index. the changes in DNA specific activity proved unacceptable as an indicator of cell proliferation in solid EMT6 tumors treated with low doses of radiation or HU.
Cell Kinetics In the Erythroid Compartment of Guinea Pig Bone Marrow: A Model Based On 3H‐Tdr Studies
Authors: Prothero J. , Starling M. , Rosse C. 
Published: May 2008

ABSTRACTA model of steady‐state erythropoiesis in the guinea pig is described. the model incorporates an unidentified progenitor compartment, as well as compartments representing proerythroblasts, basophilic, polychromatic and orthochromatic cells. A computer representation of the model permits a simulation of the labeling curves obtained in pulse and intermittent labeling regimes. It was found that a reasonable fit to the data can be achieved when the parameters for the various compartments are essentially identical. the results of a preliminary sensitivity analysis, carried out by perturbing the duration of S phase from the best fit value, are reported. the fit achieved to the data supports the hypothesis underlying the model that each compartment corresponds to one generation and that the flux within and between compartments is sequential.
THE RELATIONSHIP BETWEEN STEM CELL SEEDING EFFICIENCY AND POSITION IN CELL CYCLE
Authors: Monette F. C. , DeMello J. B. 
Published: May 2008

ABSTRACTThe seeding efficiency of colony‐forming cells from normal, regenerating and velocity‐sedimented cycling and non‐cycling narrow preparations was compared. Colony‐forming cells in cycle were found to exhibit a 50% reduction in splenic seeding when compared to normal marrow or sedimented non‐cycling cells. The results of this study indicate that the spleen colony assay underestimates the total number of colony‐forming cells by a fraction which is directly related to the number of cells in cycle.
IN VIVO EFFECTS OF 5‐FLUOROURACIL AND FTORAFUR[1‐(TETRAHYDROFURAN‐2‐YL)‐5‐FLUOROURACIL] ON MURINE MAMMARY TUMORS AND SMALL INTESTINE
Authors: Pallavicini Maria G. , Cohen A. M. , Dethlefsen L. A. , Gray J. W. 
Published: May 2008

ABSTRACTThe in vivo anti‐tumour and toxic effects of ftorafur (FT) and 5‐fluorouracil (FU) were studied in the C3H mouse. On a molar basis, FU was two to three times more potent than FT with respect to growth inhibition of murine mammary adenocarcinomas. However, FT produced less host toxicity than FU when both drugs were compared at dose levels which produced equivalent anti‐tumor effects. The differences between FT and FU with respect to tumor growth inhibition and host toxicity were reflected in their ability to suppress deoxyuridine incorporation into tumor cell and intestinal DNA, respectively.Flow cytometry (FCM) studies indicated that FT and FU were capable of producing pertubations in the DNA distribution of tumour cells. Both drugs induced an initial accumulation of cells in S phase following their administration at equivalent anti‐tumour dose levels. At later intervals, an apparent block of cell progression at the G1/S boundary was observed.Drug‐induced perturbations in the DNA distribution of tumour cells as detected by FCM correlated with results obtained by classical autoradiographic techniques using tritiated thymidine. Both procedures showed that tumor cells were capable of moving through S phase even in the presence of an apparently near complete inhibition of deoxyuridine incorporation into DNA. That such cells were, in fact, capable of synthesizing DNA at moderate rates was shown by their ability to incorporate 32P into DNA. The possible relationship of these findings to the therapeutic and toxic activities of FT and FU is discussed.
DNA FLOW CYTOMETRY OF ISOLATED KERATINIZED EPITHELIA: A METHODOLOGICAL STUDY BASED ON ULTRASONIC TISSUE DISAGGREGATION
Authors: Møller Ulla , Larsen J. K. 
Published: May 2008

ABSTRACTUltrasonication of keratinized, stratified, squamous epithelium, which had been separated from underlying tissue by means of acetic acid, resulted in disaggregation of all cellular layers in the epithelium, giving a suspension of single nuclei with mitoses preserved. This suspension was treated with RNAse and ethidium bromide for analysis by flow cytometry. From the resulting DNA histogram the G1, S and G2+ M fractions were estimated using the computer program of Fried (1976). Treatment with dithiothreitol before sonication increased the yield of nuclei in suspension and decreased the amount of debris and clumps, thereby suppressing overestimation of small S fractions.This method of preparation prior to DNA flow cytometry was useful for the study of the hamster cheek pouch epithelium and of normal and pathological human epidermis.
ESTIMATION OF EFFECTIVE EOSINOPOIESIS AND BONE MARROW EOSINOPHIL RESERVE CAPACITY IN NORMAL MAN
Authors: Walle A. J. , Parwaresch M. R. 
Published: May 2008

ABSTRACTThe eosinophil reserve capacity of the post‐mitotic granulocyte compartment in the bone marrow and the effective eosinopoiesis in three haematologically normal men have been quantified by means of kinetic parameters of [3H]thymidine flash‐labelled peripheral blood eosinophils.From (a) the time of the appearance in the blood of labelled eosinophils after the tracer injection, (b) the inflow characteristics of the labelled eosinophils in the blood and (c) the magnitude of the eosinophil granulocyte pool in the venous blood, the effective eosinopoiesis (i.e. the eosinophil turnover) was calculated to range between 0.014 and 0.031 × 109 cells/kg body weight per day (mean 0.22 × 109 cell/kg per day). The post‐mitotic eosinophil reserve capacity of the bone marrow ranged from 0.09 to 0.20 × 109 cells/kg body weight (mean 0.14 × 109 cells/kg). The large reserve pool and the high turnover rate may contribute to sudden rises of the peripheral blood oesinophil counts in some cases of eosinophilia.
THE EFFECT OF TEMPERATURE ON THE TURNOVER OF TASTE BUD CELLS IN CATFISH
Authors: Raderman‐Little R. 
Published: May 2008

ABSTRACTRenewal of taste bud cells on the barbels of channel catfish was studied. Groups of catfish, held in and acclimitized to 14°C, 18°C, 22°C and 30°C dechlorinated tap water were injected with [3H]thymidine (3.0 μCi/g body weight intraperitoneally). Barbels were sampled at various times after injection and prepared for light microscope autoradiography. Results show that epithelial cells surrounding the taste buds divide and some of their daughter cells migrate into the taste buds. The time at which 50% of the labelled cells have degenerated is taken as the average turnover time or average life span of the taste bud cells. The average life span as well as the time spent inside the taste buds is highly temperature‐dependent. At 14°C, 18°C, 22°C and 30°C the average life span is on the order of 40, 30, 15 and 12 days respectively. Further studies indicate that both light and dark staining cells of the taste bud were labelled.
STUDIES ON THE MECHANISM OF HAEMOPOIETIC STEM CELL (CFUs) MOBILIZATION
Authors: Wilschut Ina J. C. , Erkens‐Versluis Mieke E. , Ploemacher R. E. , Benner R. , Vos O. 
Published: May 2008

ABSTRACTA variety of substances can mobilize haemopoietic stem cells (CFUs) into the peripheral blood. In this study the involvement of the complement system in the mobilization process was investigated. Pretreatment of mice with the complement‐activating factor of cobra venom (CoF), which lowered the serum C3 levels to 10–25% of the normal value, could completely prevent CFUs mobilization induced by high doses of CoF, endotoxin (ET) from Salmonella typhosa, inulin, zymosan and the proteolytic enzymes proteinase and trypsin. On the other hand, mobilization induced by the polyanions dextran sulphate and the copolymer of polymethacrylic acid and styrene could not be prevented, or at least affected only slightly.There appears to be a relationship between the extent of decomplementation by CoF and the extent of CFUs mobilization induced by ET.The results indicate that certain agents mobilize CFUs via the complement system, whereas other agents induce CFUs mobilization independent of the availability of complement components.
FUNCTIONAL CELL COMPARTMENTS IN A RAT MODEL FOR HUMAN ACUTE MYELOCYTIC LEUKAEMIA
Authors: Hagenbeek A. , Martens A. C. M. 
Published: May 2008

ABSTRACTFunctional cell compartments were studied in a rat model for human acute myelocytic leukaemia (AML). This was done by tracing the distribution of injected 51Chromium‐labelled leukaemic cells in the body. It was concluded that two functional compartments can be distinguished in acute leukaemia, i.e., a rapidly exchangeable pool of cells (including the circulating blood pool, the marginal noncirculating blood pool and the rapidly exchangeable tissue pool; RETP) and a slowly exchangeable tissue pool (SETP). The sizes of these various compartments were roughly quantified at various stages of the disease by calculations based on the principle of isotope dilution and organ weight measurements. As the leukaemia progresses, the size of the SETP increases significantly relative to the size of the RETP. Simultaneously, the exchange rates of leukaemic cells between the organs and the blood decrease. The blood transit time of leukaemic cells was also significantly prolonged, as is the case in human AML.
LIPOPROTEIN INHIBITOR OF BQNE MARROW CELLS IN TUMOR‐BEARING RATS
Authors: Zucker S. , Michael Miriam S. , Lysik Rita M. , Glucksman M. J. , Reese J. , Rudin A. , DiStefano J. 
Published: May 2008

ABSTRACTThe role of a plasma inhibitor of erythropoiesis is evaluated in rats with Walker‐256 carcinoma (W‐256). Plasma from tumor‐bearing rats was treated by gel filtration chromatography (Sephadex G‐150) and fractions were combined into four pools on the basis of mol. wt. Inhibitory activity was assayed by adding an aliquot of the plasma fractions to normal rat marrow cells which were cultured for 24 hr with and without erythropoietin. 59Fe‐heme synthesis, [3H]thymidine DNA synthesis, and 14C‐leucine protein synthesis were studied. The results indicated that cultures containing the high mol. wt. pool (>400,000 daltons) had significantly decreased heme, DNA and protein synthesis. This inhibitor also diminished the response to erythropoietin in polycythemic mice. The lower mol. wt. pool stimulated heme synthesis in vitro. To identify the inhibitor further, plasma lipo‐protein classes were isolated by density gradient ultracentrifugation. The very low density lipoprotein (VLDL) and chylomicron fractions markedly inhibited DNA, protein and heme synthesis. Low density and high density lipoprotein fractions were inactive. A lipoprotein inhibitor of erythropoiesis was also identified in cancerous ascitic fluid, and to a lesser degree, in normal rat plasma. We suggest that this VLDL inhibitor of marrow erythropoiesis is a contributing factor in the anaemia of cancer.
SPERMATOGONIAL CHALONE(S): EFFECT ON THE PHASES OF THE CELL CYCLE OF TYPE A SPERMATOGONIA IN THE RAT
Authors: Irons Margaret J. , Clermont Y. 
Published: May 2008

ABSTRACTAdult rats with X‐irradiated testes were used to analyze the effect of the spermatogonial chalone(s) on the phases of the cell cycle of type A spermatogonia. Twelve days after irradiation, the animals were used in two experiments designed to test the existence of hypothetical G2 and S phase chalones. For the G2 assay, rats injected twice with testicular extract (Group I), liver extract (Group II) or physiological saline (Group III) were killed 10 hr after the initial injection. Mitoses of type A, Intermediate and type B spermatogonia were counted in whole mounts of dissected seminiferous tubules. To test for an S phase inhibitor, two groups of rats were given multiple injections of either testicular extract (Group IV) or saline solution (Group V). Twenty‐two hr after the first injection they were injected with [3H]thymidine and killed 2 hr later. Silver grains over labelled type A nuclei were counted in radioautographed sections of testes from these animals. The average grain counts were identical in Groups IV and V, indicating that the testicular extract did not affect type A spermatogonia during the S phase. Counts of type A mitoses in Groups I, II and III revealed that in the animals injected with the testicular extract (Group I) the number of divisions was 50% lower than in the control groups (Groups II and III). In contrast, mitotic activity of differentiating spermatogonia (In + B) was similar in all three groups of animals. This result is attributed to a testicular chalone which specifically inhibits type A spermatogonia during the G2 phase of the cell cycle. Indirect evidence for a G1 spermatogonial chalone is also presented, as a result of an analysis of published data (Clermont & Mauger, 1974).
CELL PROLIFERATION OF CARCINOMA IN BILHARZIAL BLADDER: AN AUTORADIOGRAPHIC STUDY
Authors: Awwad H. K. , Hegazy M. , Ezzat S. , El‐Bolkainy N. , Burgers M. V. 
Published: May 2008

ABSTRACTThe rate of cell production in thirty‐five cases of carcinoma in Bilharzial bladder was evaluated from the labelling index after in vitro incubation with [3H]TdR. Squamous cell carcinoma was the most frequent histological type in this series and had a median LI of 8.0% which corresponds to a potential doubling time of 5.9 days. In squamous cell tumours the LI increased with the histological grade. Transitional cell tumours had a somewhat greater LI.In all histological types the LI was significantly greater in the deep infiltrating parts of the tumour than in the superficial parts. The discrepancy between the estimated potential doubling time and the growth rate normally attributed to such tumours suggests the existence of an extensive cell loss factor. Areas of focal or diffuse mucosal hyperplasia were associated with increased LI.
CYTOTOXIC EFFECTS OF COLCEMID OR HIGH SPECIFIC ACTIVITY TRITIATED THYMIDINE ON CLONOGENIC CELL SURVIVAL IN B6CF1 MICE
Authors: Hanson W. R. , Fry R. J. M. , Sallese A. R. 
Published: May 2008

ABSTRACTHigh specific activity tritiated thymidine (HSA‐[3H]TdR) and colcemid were given in cytotoxic doses and regimens to B6CF1/Anl mice. The number of cells per intestinal crypt was reduced by the S‐phase‐specific HSA‐[3H]TdR and the metaphase blocking and cytotoxic effect of multiple injections of colcemid. In 50‐day old mice, the cytotoxic effect of multiple injections of colcemid reduced both the number of cells per crypt and the clonogenic cell survival. However, the number of surviving intestinal clonogenic or stem cells, assayed by the micro‐colony technique, did not change in 110–130‐day old mice. These data suggest that most of the cells at risk from these cytotoxic agents are not clonogenic in adult 110–130‐day old mice but are the cells in amplification division. However, since the stem cells of young mice are more susceptible to colcemid, they are apparently in a more rapid cell cycle than those of older mice. The clonogenic cell survival measured in 110–130‐day old mice after a single radiation dose of 14 Gy (1400 rad) responded in a non‐linear way to increasing time of continuous colcemid cytotoxicity. These data suggest that the intestinal stem cells can respond to amplification compartment cell death by a shortening of their cell cycle and thus, over time, the number of stem cells at risk to colcemid cytotoxicity increases.