bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE ROLE OF THE SPLEEN IN THE REPOPULATION OF THE HAEMOPOIETIC SYSTEM OF HEAVILY‐IRRADIATED MICE
Authors: Silini G. , Andreozzi U. , Pozzi L. V. 
Published: May 2008

AbstractThe respective role of the spleen or of the bone marrow in the regeneration of the haemopoietic progenitor compartment of heavily‐irradiated mice has been investigated. Splenectomy was used to this end in animals injected with exogenous isogenic cells or regenerating from endogenous spleen or marrow cells. Analysis of the data as a function of time shows that the presence of the spleen affects marrow CFU repopulation only at the early post‐irradiation stages. The expansion of the marrow progenitor pool proceeds, however, rather independently of the spleen and marrow CFU remain eventually as the main source of haemopoietic cells in the surviving mice. Thus the reaction of the spleen may be envisaged as a fast, important but transient contribution to the overall haemopoietic function of heavily‐irradiated animals.
A FAST AND ACCURATE METHOD FOR CALCULATING ENGELBERG'S SYNCHRONIZATION INDEX
Authors: Bakke O. , Pettersen E. O. 
Published: May 2008

AbstractA method is described which makes a fast and accurate calculation of Engelberg's synchronization index possible. The calculation is only based on the growth curve for the synchronous and the corresponding asynchronous population, and makes it unnecessary to calculate the curve for the normalized rate of cell division.
THE ‘TRANSITION PROBABILITY MODEL’ AND THE REGULATION OF PROLIFERATION OF HUMAN DIPLOID CELL CULTURES DURING AGING
Authors: Grove GAry L. , Cristofalo Vincent J. 
Published: May 2008

AbstractGenealogies derived from time‐lapse cinemicrophotographic studies of aging human diploid cell cultures were analysed in terms of the ‘transition probability’ model. It was found that the distribution of intermitotic times obtained from middle passage cells deviated only slightly from that predicted by the model. In contrast, the plot for late passage cultures did not fit the predicted pattern and appeared to be composed of multiple curves. These changes are discussed in reference to cellular senescence as expressed by normal human diploid cells in vitro.
EFFECT OF MECHANICAL STIMULATION ON CELL PROLIFERATION IN MOUSE EPIDERMIS AND ON GROWTH REGULATION BY ENDOGENOUS FACTORS (CHALONES)
Authors: Bertsch Stefan , Csontos Katharina , Schweizer Jurgen , Marks Friedrich 
Published: May 2008

AbstractMechanical stimulation of dorsal mouse skin by skin massage or removal of the horny layer results in a mutually comparable increase in DNA‐labelling and mitotic activity. However, only after injury such as removal of the horny layer hyperplasia develops. This phenomenon, called ‘hyperplastic transformation’ is characterized by a transient abolition of the epidermal G1 chalone responsiveness. There is some indication that the susceptibility to a heat labile factor, probably the epidermal G2 chalone, is not affected. Skin massage neither interferes with the responsiveness to epidermal G1 chalone nor induces ‘hyperplastic transformation’. Mouse tail epidermis shows a ‘functional hyperplasia’ and responds to the G1 chalone. To explain these observations, it is assumed that the epidermal stem cell population is heterogeneous consisting of G1 chalone‐sensitive and G1 chalone‐insensitive cells.
STUDIES ON THE MECHANISM OF DIURNAL VARIATION OF PROLIFERATIVE INDICES IN THE SMALL BOWEL MUCOSA OF THE RAT
Authors: Al‐Dewachi Hutaifa S. , Wright Nicholas A. , Appleton David R. , Watson Alexander J. 
Published: May 2008

AbstractIn the rat small bowel mucosa significant variation was found in both the labelling and the mitotic indices with time of day. The zenith and the nadir of labelling and mitotic activity coincided at 15.00 and 02.00 hours respectively. Small changes were found in the ‘cut‐off’ position, but this variation in proliferative compartment size was insufficient to account for the comparatively wider fluctuations in proliferative indices. Measurements of the rate of entry into mitosis, using metaphase arrest with vincristine at three widely separated times during the day, showed no significant change.Changes in the growth fraction or in the birth rate as measured cannot account for diurnal variation in the proliferative activity of the small bowel mucosa. We propose a hypothesis which involves diurnal fluctuations in the transit times through G1 and through G2.
PROLIFERATION RATE OF HAEMOPOIETIC STEM CELLS AFTER DAMAGE BY SEVERAL CYTOSTATIC AGENTS
Authors: Nečas E. , Neuwirt J. 
Published: May 2008

AbstractThe haemopoietic tissue of mice was damaged by different cell‐cycle‐stage specific and cell‐cycle‐stage non‐specific cytostatic agents. The proliferation rate among the surviving pluripotential stem cells, i.e. those cells forming colonies in spleens of lethally irradiated mice (CFUs), was then investigated.The results suggest that, at least in the CFUs population, the cells which synthesize DNA in the S phase of the cell cycle inhibit the entry of the non‐proliferating G0 cells into cell cycle. This evidence was based on the ability of three cytostatic agents, hydroxyurea, cytosine arabinoside and methotrexate, which are toxic specifically to the S phase cells to increase the proliferation in the CFUs population. This increase was quite out of proportion to the small amount of damage they caused to the population. Colchicine, which kills cells in mitosis, and ionizing irradiation, damaging cells in all stages, proved to be much weaker stimulators of proliferation.It has been suggested that a mechanism for the control of cellular proliferation might be based on the negative feedback in the cell cycle. In this feedback control loop the cells which are preparing for cell division in the S phase of the cell cycle inhibit the entry of the non‐proliferating G0 cells into cell cycle.
CALCIUM AND IONOPHORE A‐23187 AS INITIATORS OF DNA REPLICATION IN THE PLURIPOTENT HAEMOPOIETIC STEM CELL
Authors: Gallien‐Lartigue O. 
Published: May 2008

AbstractThe proliferation rate of the haemopoietic stem cells of the mouse bone marrow can be stimulated by an increase in calcium influx. This key event may be brought about by raising the external calcium concentration or, at lower calcium levels, by use of A‐23187 as calcium carrier, within definite dose ranges depending on the Mg2+: Ca2+ molar ratio in the incubation medium. The hypothesis is postulated of an accelerated influx of Ca+ as the possible common mediator of the effects of the various types of agents known to control the CFU cell cycle.
REGENERATION OF CFUs IN THE MARROW OF MICE EXPOSED TO 300 RADS AFTER HAVING RECOVERED FROM 950 RADS
Authors: KEDO A. , BARONE JUDITH , FRIED W. 
Published: May 2008

AbstractExposure to 950 rads 60Co radiation has been reported to cause long‐lasting damage to the hematopoietic stroma (HS), although the size of the CFUs population recovers to pre‐irradiation levels. In these studies HS damage was detected only after subcutaneously implanting the femurs of the irradiated mice into syngeneic hosts. To exclude the possibility that what was considered to be HS damage was merely caused by artifacts due to the process of implantation in a new host, we compared the rate of regeneration of CFUs in mice which had recovered from 950 rads prior to receiving 300 rads 60Co radiation (950 + 300 rads group) with that of mice which received only 300 rads (0 + 300 rads group).The CFUs population in the 950 + 300 rads group grew exponentially for 2 weeks at a rate which did not differ significantly from that of CFUs in the 0 + 300 rads group. However, the rate of CFUs growth reached a plateau before full recovery was achieved in contrast to that in the 0 + 300 rads mice.We therefore conclude that the incomplete regeneration of CFUs in the marrows of 950 + 300 rads mice was most likely caused by X‐irradiation‐induced damage to the HS rather than damage to the inherent repopulating potential of the CFUs per se.
EHRLICH ASCITES TUMOR (EAT) CHALONE EFFECTS ON NASCENT DNA SYNTHESIS AND DNA POLYMERASE ALPHA AND BETA
Authors: Nakai George S. 
Published: May 2008

AbstractEAT chalone effects on nascent DNA synthesis and DNA polymerase were examined. Concentration related inhibition of 3H‐thymidine (3H‐TdR) incorporation into EAT cell DNA was noted over a chalone range of 50–200 μg/ml. RNA synthesis was not affected, but protein synthesis decreased an average of 82% during 3 hr. Nascent DNA pulse‐labeled for 2 min was normally incorporated into bulk DNA in the presence of chalone, but crude α and β‐polymerase activities were inhibited. Crude DNA polymerase from C3H mouse kidney and spleen was also partially inhibited by EAT chalone, suggesting non‐specific inhibition of DNA polymerase. Preincubation studies of chalone with crude EAT DNA polymerase or ‘gapped’ DNA primer had no effect on chalone activity. Chalone may control mitotic activity by inhibiting α‐ and β‐polymerase activity, thereby decreasing nascent DNA synthesis. Nascent DNA is incorporated normally into bulk DNA in the presence of chalone, indicating that DNA ligase is not inhibited.
A DEFICIENCY OF HEMATOPOIETIC STEM CELLS IN STEEL MICE
Authors: McCarthy K. F. , Ledney G. D. , Mitchell R. 
Published: May 2008

ABSTRACTIn the present study, population sizes of high self‐renewal potential stem cells, i.e. colony forming units (CFU), and low self‐renewal potential stem cells, i.e. transient endogenous colony forming units (TE‐CFU) in Sl/Sld mice and their normal congenic littermates were measured and compared. By correcting for differences in the seeding efficiency ‘f’, it was possible to demonstrate that Sl/Sld mice suffer a deficiency of both stem cell populations. Therefore, it is concluded that the defective stromal tissue of the Sl/Sld mouse does not support normal size stem cell populations. However, as noted in the discussion, it remains an open question as to whether the defective stromal tissue supports normal erythroid differentiation at the stem cell level.
REGULATION OF BONE MARROW CELL GROWTH IN DIFFUSION CHAMBERS: THE EFFECT OF GRANULOCYTE EXTRACTS
Authors: Løvhaug Dagfinn , Bøyum Arne 
Published: May 2008

ABSTRACTHypotonic lysis of mature human blood granulocytes yielded an extract which reduced granulopoiesis and enhanced macrophage formation of mouse bone marrow cells cultured for 7 days in diffusion chambers (DC). The low molecular weight fraction (MW < 15,000–25,000 Daltons) obtained by Amicon filtration of the extract, reduced granulopoiesis without affecting macrophage formation. The high molecular weight fraction (MW > 15,000–25,000 Daltons) reduced the number of granulocytes and increased the number macrophages. Erythrocyte extract increased the macrophage formation in DC but did not alter the number of granulocytes. The spleen colony assay showed that the granulocyte extract increased the number of CFU‐S in DC. It is suggested that the granulocyte extract contain an inhibitor of stem cell differentiation to myeloid cells thereby reducing the number of proliferative granulocytes in DC 7 days later. The inhibitor of differentiation may lead to an increased self renewal of the stem cell in the DC system.
THE EFFECT OF VINCRISTINE ON MOUSE JEJUNAL CRYPT CELLS OF DIFFERING CELL AGE: DOUBLE LABELLING AUTORADIOGRAPHIC STUDIES USING 3H‐ AND 14C‐TdR
Authors: Jellinghaus W. , Schultze B. , Maurer W. 
Published: May 2008

ABSTRACTThe mechanism of action of the alkaloid vincristine (VCR) has been investigated in vitro on HeLa cells in culture and in vivo on jejunal crypt cells of the mouse. The in vitro experiments with HeLa cells show that VCR affects not only mitotic but also interphase cells. The VCR‐affected cells first continue their passage through the cell cycle undisturbed but after reaching mitosis they are arrested in metaphase. This agrees well with the results obtained by Madoc‐Jones & Mauro (1968) and Madoc‐Jones (1973) on synchronized cell cultures.Until now there has been no investigation of the mechanism of action of VCR in vivo. This is due to the absence of a suitable technique for synchronization in vivo. The present study is based on a method which permits the assessment of the VCR sensitivity as a function of the cell age without synchronization in the usual sense.The jejunal crypt epithelium of the normal mouse was double labelled with 3H‐ and 14C‐thymidine (TdR) in such a way as to produce a narrow subpopulation of crypt cells with a maximum age difference of 1 hr. On autoradiographs these cells can be distinguished by their characteristic labelling from other cells. As this ‘pseudo’‐synchronized subpopulation passes through the cycle the effect of VCR can be studied, i.e. one can analyse the effect in well‐defined time intervals of the cycle. The results show that the effect of VCR is the same in vivo as in vitro. The crypt cells which are affected by VCR in interphase continue their passage through the cycle, but upon entering mitosis they are arrested in metaphase. VCR has, at the concentration used in the present study, no effect on the duration of the S and G2 phases. The necrotic cells seen after VCR application are formed from arrested metaphases.
GROWTH STIMULATION OF SPARSE, SERUM DEPRIVED AND OF CONFLUENT, CONTACT INHIBITED MAMMALIAN FIBROBLASTS BY A PREPARATION OF 3′:5′‐CYCLIC AMP PHOSPHODIESTERASE
Authors: Lawrence David A. , Dézelée Philippe , Jullien Pierre 
Published: May 2008

ABSTRACTResting mammalian fibroblasts, either sparse and maintained in a serum‐free medium, or confluent and contact inhibited, are stimulated to divide by treatment with a preparation of 3′: 5′‐cyclic AMP phosphodiesterase. This enzyme preparation contained a low level of trypsin‐like and α‐chymotrypsin‐like activity, but its effect on cell growth could not be mimicked by pure, crystallized trypsin and α‐chymotrypsin at concentrations equivalent to their contamination in the above preparation. Preincubation of the 3′: 5′‐cyclic AMP phosphodiesterase preparation with the protease inhibitor, phenyl methane sulfonyl fluoride, did not affect, either, its stimulation of DNA synthesis in fibroblasts, or its enzymatic hydrolysis of cyclic AMP.
EFFECT OF PEPSIN PRETREATMENT ON PULSE‐CYTOPHOTOMETRIC DNA HISTOGRAMS
Authors: Beck H.‐P. 
Published: May 2008

ABSTRACTSamples of mitotic L‐cells were investigated after different preparation and staining procedures using the technique of pulse‐cytophotometry. It is shown that most mitotic cells which should appear in the second peak of the DNA histogram are disintegrated or separated into halves by pepsin pretreatment. Hence, the designation‘G2+ M’for the second peak is not correct for this preparative method. This should be taken into account in cell kinetic investigations performed after pepsin pretreatment.
STUDIES ON THE POPULATION KINETICS OF THE WALKER CARCINOMA BY AUTORADIOGRAPHY AND PULSE CYTOPHOTOMETRY
Authors: Erbe W. , Linden W. A. , Reddy S. B. , Zywietz F. , Baisch H. 
Published: May 2008

ABSTRACTThe proliferation parameters of the Walker carcinoma were estimated from both in vivo and in vitro measurements. The transplantable Walker carcinoma 256 was grown in male inbred BD1 rats. During exponential growth, 5‐6 days after transplantation, a PLM curve was performed, yielding estimates of Tc ≅ 18.0 hr, Ts ≅ 6.4 hr, TG2+M≅ 4.1 hr. With the double labelling technique in vitro under 2.2 atm oxygen we obtained: Tc ≅ 18.2hr, Ts ≅ 8.2 hr, TG2+M≅ 2.0hr. From pulse cyto‐photometry DNA content histograms the fractions of cells in the cell cycle phases were calculated using a computer program: fG1≅ (47.6 ± 1.1)%, fs≅ (34.1 ± 1.0)%, fG2+M≅ (18.3 ± 1.5)%. These fractions remained constant between the fifth and the twelfth day after transplantation. At that time the tumour growth had already slowed down appreciably. The growth fraction determined by repetitive labelling was 0.96 on the fifth and 0.93 on the seventh and eleventh day. The cell loss factor was φ≅ 17% during exponential tumor growth and increased to about 100% between the tenth and twelfth day. The agreement of the cell kinetic data determined by autoradiography from solid tumours in vivo (PLM, continuous labelling) and autoradiography as well as pulse cytophotometry from in vitro experiments (excised material) was satisfactory.
POST‐MITOTIC AGE OF MONONUCLEAR CELLS MIGRATING INTO TA‐3(St) SOLID TUMORS
Authors: Kaizer L. , Lala P. K. 
Published: May 2008

ABSTRACTSubcutaneous transplantation of 5 × 106 TA‐3(St) mammary carcinoma cells into A/J mice produced rapidly growing tumors that showed a substantial accumulation of lymphocytes, monocytes and macrophages. This must have resulted primarily from an influx of circulating cells, since none of the cell types exhibited any significant local proliferation as indicated by 1 hr 3H‐TdR uptake. The post mitotic age of the various leukocyte types in circulation of normal and tumor bearing animals, and those appearing within the tumors, was evaluated by a repeated 3H‐TdR labeling protocol designed to label newly formed leukocytes. Tumor transplantation (or injection of an equivalent volume of saline in control animals) was preceded by thirteen 3H‐TdR injections (12.5 μCi every 8 hr) and followed by eight more injections at equivalent intervals. Animals were serially sacrificed at 5‐14 days after tumor transplantation or saline injection. Total lymphocyte labeling in the blood during these intervals was higher in tumor bearing mice (approximately 25% between 5 and 12 days) than in the saline injected controls (approximately 20%), indicating that tumor transplantation resulted in an increase in the proportion of young lymphocytes in circulation. More significantly, a much higher labeling (57‐60% at 5‐12 days) was exhibited by lymphocytes isolated from the tumors, indicating selective migration (and/or retention) of newly formed lymphocytes within the tumor. This finding applied to lymphocytes in all size categories. Although blood monocyte labeling in the control and experimental animals was similar (e.g. 83% at day 5 and 52% at day 14), significantly higher labeling (e.g. 93% and 70% at the respective intervals) was exhibited by monocytes isolated from tumors. This suggested a preferential accumulation of young monocytes at the tumor site. An identical macrophage labeling pattern compared to that shown by monocytes within the tumor indicated a rapid monocyte‐macrophage transition. Since these findings in the present strain‐specific solid tumor are similar to those previously obtained in this laboratory in the strain‐nonspecific Ehrlich ascites tumor, the phenomenon of selective localization of newly formed mono‐nuclear leukocytes appears to be a general occurrence in transplanted murine tumors.
MODULATION OF IN VITRO ERYTHROPOIESIS: ENHANCEMENT OF ERYTHROID COLONY GROWTH BY CYCLIC NUCLEOTIDES
Authors: Brown James E. , Adamson John W. 
Published: May 2008

ABSTRACTMammalian erythropoiesis, as assayed by erythroid colony formation in vitro, is enhanced by cyclic adenosine nucleotides and agents which are capable of raising intracellular cyclic AMP (cAMP) levels. With canine marrow cells as target, this enhancement was shown to be specific for cAMP and its mono‐ and dibutyryl derivatives. Adenosine and its derivatives, such as AMP, ADP and ATP, and other cyclic nucleotides, such as cGMP, dibutyryl‐cGMP, cCMP and cIMP and sodium butyrate were inactive. The phosphodiesterase inhibitor, RO‐20‐1724, and the adenyl cyclase stimulator, cholera enterotoxin, both markedly increased colony numbers. Studies with tritiated thymidine showed that about 50% of the cells responding to either erythropoietin (ESF) or dibutyryl cAMP (db‐cAMP) were in DNA synthesis. However, by unit gravity sedimentation velocity analysis, the peak of ESF‐responsive colony forming cells sedimented more rapidly (8.7 ± 0.2 mm/hr) than the peak of db‐cAMP‐responsive cells (7.5 ± 0 mm/hr). These results demonstrate that adenyl cyclase‐linked mechanisms influence in vitro erythropoietic proliferation and suggest that other hormones and simple molecules might interact with surface receptors and thus modulate the action of ESF at the cellular level.
HYPERSENSITIVITY REACTIONS IN THE SMALL INTESTINE
Authors: MacDonald T. T. , Ferguson Anne 
Published: May 2008

ABSTRACTAllograft rejection of fetal intestine and graft‐versus‐host (GvH) disease have been used to study the effects of cell‐mediated immune reactions on epithelial cell kinetics in mouse small intestine. In heterotopically transplanted isografts the cell production rate per crypt was similar to that in normally sited small intestine of the same age. However there was a six‐fold increase in the rate of cell production per crypt during allograft rejection and a three‐fold increase during GvH disease. Furthermore animals with GvH disease developed villous atrophy and had fewer crypts per villus than littermate controls. At the age of 19 days cell production per villus per hour was 97.5 in animals with GvH disease compared with 54.6 in controls.These results indicate that the pathological entity of ‘partial villous atrophy’evolves in two distinct phases. Phase 1, a state of increased cell turnover with crypt hyperplasia but villi of normal length precedes the development of Phase 2, true villous atrophy.
ALTERATION OF CELLULAR PROLIFERATION IN THE ILEAL EPITHELIUM OF SUCKLING AND WEANED RATS: THE EFFECTS OF ISOPROTERENOL
Authors: Klein Robert M. 
Published: May 2008

ABSTRACTThe purpose of this study was to analyse cell proliferation in the ileum before and after neonatal closure to macromolecules and to determine the effects of the sympathomimetic amine, isoproterenol (IPR), on cell cycle parameters. 8‐ and 28‐day‐old rats were employed in this study representing the neonatal periods of pre‐ and post‐closure ileum respectively. The duration of the cell cycle phases was determined by the percentage of labeled metaphases technique (PLM) with computerized analysis of the curves. The generation cycle time was longer in 8‐day‐old suckling rats (18.63 hr) as compared to the older weaned rats (11.85 hr), and most of this 6.78 hr difference was in the G1‐period (4.5 hr). Other proliferative indices were also lower in the suckling rats—mitotic index (1.9 ± 0.4% as compared to 6.7 ± 0.9%), labelling index (26.8 ± 2.5% versus 44.2 ± 2.6%) and migration rate measured as per cent labeled villus cells (8.9 ± 3.1% versus 45.2 ± 3.4%). IPR was found to inhibit cellular proliferation in the ileal epithelium of both age groups. The cell cycle of the ileal epithelium of 8‐day‐old rats was lengthened from 18.63 to 21.07 hr and 28‐day‐old rats from 11.85 to 13.98 hr. IPR produced a decrease in mitotic index from 1.9 ± 0.4% to 1.6 ± 0.4% in pre‐closure ileum and from 6.7 ± 0.9% to 5.1 ± 0.6% in post‐closure ileum. Labeling index decreased from 26.8 ± 2.5% to 20.0 ± 2.0% in 8‐day‐old rats and from 44.2 ± 2.6% to 31.1 ± 3.0% in 28‐day‐old rats after IPR administration. There were also significant differences in growth fraction between age groups and a significant decrease in growth fraction after IPR‐treatment. From the results of this study it appears that β‐adrenergic stimulation has an inhibitory effect on neonatal ileal epithelium.