bluuebunny/crossref_metadata_2025_split huggingface dataset:
IN VITRO PRODUCTION OF COLONY‐STIMULATING ACTIVITY. I. EXPOSURE OF MOUSE PERITONEAL CELLS TO ENDOTOXIN
Authors: Eaves A. C. , Bruce W. R. 
Published: May 2008

ABSTRACTCell suspensions, obtained from bone marrow, spleen, thymus, lung, liver, and from peritoneal washings, were incubated in vitro with low concentrations of endo‐toxin and the supernatant media assayed for colony‐stimulating activity (CSA). Peritoneal cells were markedly responsive. The kinetics of CSA production in vitro by peritoneal cells were not remarkably different from that seen in vivo following intravenous administration of endotoxin. The activities of CSA prepared from peritoneal cells and serum were compared following serial dilution; both gave a similar linear relationship when plotted as a function of log‐concentration. The bulk of the CSA was produced by adherent peritoneal cells. Separation of peritoneal cells by velocity sedimentation showed that the CSA‐producing cell had a sedimentation velocity of 7 mm/hr. Cells with this sedimentation velocity were found to be large mononuclear cells which demonstrated adherence and phagocytosis.
CFU‐C YIELDS FROM THE HAEMOPOIETIC TISSUES OF NORMAL AND LEUKAEMIC RFM MICE
Authors: Gordon Myrtle Y. , Coggle J. E. 
Published: May 2008

ABSTRACTSpleen and bone marrow cells from normal and leukaemic RFM mice have been assayed for numbers of colony forming cells in soft agar (CFU‐C). The fluctuations in CFU‐C yield observed during the development of myeloid leukaemia are similar to the results from in vitro experiments set up to test a model, and are not incompatible with the idea that interaction between normal and leukaemic cells may modify the yield of CFU‐C under the present conditions of culture. Colonies grown from leukaemic spleen and bone marrow cells appear to be derived from the residual population of normal haemopoietic cells within the leukaemic mouse.
THE EPIDERMAL PROLIFERATIVE UNIT: THE POSSIBLE ROLE OF THE CENTRAL BASAL CELL
Authors: Potten Christopher S. 
Published: May 2008

ABSTRACTA model is suggested for the organization of the epidermis based on the ordered structure of the differentiating layers, as demonstrated by published work. This ordered structure enables one to look through the epidermis at the basal cell nuclei and to see their arrangement beneath the differentiating column of cells. In dorsal skin from male DBA‐2 mice there are 10.6 basal nuclei beneath a column of cells. The central nucleus of the group responds slightly earlier and more effectively than the rest to stimulation, is cycling more slowly than the majority of the basal nuclei and may spend significant periods of time out of cycle.The skin appears to contain a series of fairly independent proliferative units, each of which contain ten or eleven basal nuclei and eight to ten superficial cells of which only the youngest one or two retain their nuclei. At the centre of each group of basal nuclei is a cell that behaves differently from the rest and which is present in the skin in numbers compatible with the number of clonogenic cells. It is suggested that this represents the basic stem cell of the unit.
ADAPTATION OF HEMOPOIETIC TISSUE RESULTING FROM ESTRONE‐INDUCED OSTEOSCLEROSIS IN MICE
Authors: Morse Bernard S. , Giuliani Dennis , Soremekun Maurice , DiFino Santo , Giuliani E. Regina 
Published: May 2008

ABSTRACTThe redistribution of hemopoietic tissue resulting from estrone‐induced osteosclerosis in the mouse was studied. As the marrow was gradually replaced by bone, extramedullary hematopoiesis in the spleen increased at a rate sufficient to maintain hemopoietic homeostasis.The total numbers of colony forming units (CFU) in the tibia and spleen as well as the proportion of CFU in cycle was assessed. After five injections of estrone, tibial CFUs decreased to 2% of control values whereas splenic CFUs increased approximately nine‐fold. The proliferative capacity of the splenic CFU was also increased in the estrone‐treated animals. The increased numbers of splenic CFUs as well as the increased proliferative capacity of this compartment are probably related to the ability of extramedullary hematopoiesis in the spleen to compensate for a marrow that has been replaced by bone.
KINETICS OF DEVELOPMENT OF EMBRYONIC ERYTHROID CELLS
Authors: Wheldon T. E. , Kirk J. , Orr J. S. , Paul J. , Conkie D. 
Published: May 2008

ABSTRACTEmbryonic erythropoiesis is an intrinsically non‐steady‐state process. A method of non‐steady‐state analysis is employed to approximately determine the kinetics of maturation of embryonic erythroid cells during the hepatic phase of erythropoiesis in the mouse.It appears from this analysis that embryonic erythroid cells have significantly shorter maturation times than their adult counterparts. In the embryo, there is insufficient time for more than three divisions between the proerythroblast and the orthochromatic erythroblast.
AN AUTOMATIC SYNCHRONIZER FOR SUSPENSION CULTURE OF L5178Y CELLS
Authors: Okada S. , Shinohara K. 
Published: May 2008

ABSTRACTThe excess thymidine‐colcemid synchronization method for mouse leukemia L5178Y was automated by deleting the removal of excess thymidine. The synchronizer adds thymidine and colcemid at predetermined times and makes the population accumulated at mitosis available at a designated time. The apparatus is inexpensive to build, easily operated and applicable to large volumes of a static suspension culture.
THYMIDINE SUICIDE IN VIVO AND IN VITRO OF SPLEEN COLONY FORMING AND AGAR COLONY FORMING CELLS OF MOUSE BONE MARROW
Authors: Blackett N. M. , Millard R. E. , Belcher H. M. 
Published: May 2008

ABSTRACTThe ‘thymidine suicide’technique for indicating differences in the proliferation rate of early haemopoietic progenitor cells (spleen colony forming and agar colony forming cells) in C57BL mice has been evaluated. Special care was taken to use the same bone marrow cell suspension for the two progenitor cell assays. Both the in vivo and the in vitro techniques were employed.Following 3H‐TdR in vivo, about 20% of both types of progenitor cell are killed in normal mice; however, after incubation in vitro with 3H‐TdR, 35% of agar colony forming cells but only 4% of spleen colony forming cells are killed. Reasons for the difference between the in vivo and the in vitro results are discussed. With bone marrow from continuously irradiated animals, the thymidine suicide for both agar colony forming and spleen colony forming cells is in the range 42–50%, and there is no difference between in vivo and in vitro suicide.The in vivo results support the conclusion, based on the effect of proliferation dependent cytotoxic agents, that in C57BL mice agar colony forming and spleen colony forming cells are proliferating at the same rate in normal animals, and are speeded up to the same extent by continuous γ‐irradiation. It is considered that in normal C57BL mice the in vitro method does not give a correct estimate of the proliferation rate of these progenitor cells.It would seem that the similarity in the proliferation rate of agar colony forming and spleen colony forming cells in C57BL mice is not true for other strains of mice: indeed using normal CBA and in vivo suicide, we have shown a significantly greater thymidine suicide for agar colony forming cells compared to spleen colony forming cells.
SENSITIVITY OF EARLY EMBRYONIC THYMIC LYMPHOID DEVELOPMENT TO 3H‐THYMIDINE OF HIGH SPECIFIC ACTIVITY
Authors: Juhlin Roger , Alm Gunnar V. 
Published: May 2008

ABSTRACTThe pulse technique, using high specific activity 3H‐TdR to selectively kill cells in cell cycle, was applied to the thymic anlagen of chick embryos. With optimal specific and total 3H‐TdR activities and pulse times of 2–4 hr the subsequent lymphoid development in organ culture of the thymic anlagen of 10‐day‐old chick embryos could be almost completely inhibited.The most important effect of the 3H‐TdR was on the lymphoid precursor cells of the anlagen. The thymic epithelium appeared more resistant to 3H‐TdR and allowed a lymphoid development of pulsed anlagen grafted to the chorioallantoic membrane of chick embryos when new lymphoid precursor cells were provided. The lymphoid precursor cells of the thymic anlagen of 10‐day‐old chick embryos therefore appeared to be in cell cycle with short generation time.The thymic anlagen of 8‐, 9‐ and 10‐day‐old but not 7‐day‐old embryos showed a lymphoid development in organ culture. They did not differ with respect to the sensitivity to hot pulses of 3H‐TdR. Thus no evidence of a lag in the onset of lymphoid precursor cell proliferation during the development of the early embryonic chick thymus was noted.
CELL POPULATION KINETICS OF TRANSPLANTED AND METASTATIC LEWIS LUNG CARCINOMA
Authors: Simpson‐Herren L. , Sanford A. H. , Holmquist J. P. 
Published: May 2008

ABSTRACTThe growth rate of Lewis lung carcinoma, either as primary subcutaneous tumors or as spontaneous lung metastases, decreases with increasing age or mass. The length of the median cell cycle of the primary tumors increased from 17.6 hr at Day 5 to 25.9 hr at Day 21 with a concomitant increase in experimental doubling time from 2.5 to 9.6 days. The length of the median cell cycle of the metastatic lung nodules was 15.2 hr in the mice bearing 21‐day primary tumors. Two mathematical models were used to analyse the per cent labeled mitoses data and the results are given for comparison.The labeling index of the primary tumors decreased in a nearly linear manner with time postimplant and the percentage of cells labeled in the metastatic nodules was higher than in the primary tumors when measured in the same hosts.
DELAYED RESPONSE TO ERYTHROPOIETIN IN POLYCYTHAEMIC ANIMALS TREATED WITH CYTOTOXIC AGENTS
Authors: Millar J. L. , Constable T. B. , Blackett N. M. 
Published: May 2008

ABSTRACTThis communication deals with the phenomenon of delayed response to erythropoietin and provides many examples of this phenomenon with a variety of cytotoxic agents. Explanations for the delayed response presented by other authors have been examined in the light of the available experimental evidence. These explanations, generally involving restoration of the depleted ERC compartment before differentiation into proerythroblasts, have been shown to be unlikely. An alternative explanation for the delayed response involving continuous maturation of a committed stem cell to ERC and sensitization of cells in this maturation pathway to erythropoietin after treatment with cytotoxic agents, is presented.
THE EFFECT OF FETUIN AND OF SPLEEN EXTRACTS ON HEMATOPOIETIC PRECURSORS AND ON DIFFERENTIATED HEMATOPOIETIC CELLS IN IRRADIATED MICE
Authors: Dons Robert , Knospe William H. , Trobaugh Frank E. , Fried Walter 
Published: May 2008

ABSTRACTInjection of extracts from normal mouse spleen tissue into irradiated mice enhance the rate of regeneration of colony forming units (CFU‐S) in the femoral marrow. This effect was most pronounced when spleen extract was injected between 24 hr before and 24 hr after the time of irradiation, and was observed only during the first week after a single injection of extract. Another result of injecting spleen extract was an immediate and transient decrease in the marrow cellularity and particularly in the number of mature myeloid cells in the marrow. Fetuin produced comparable effects on the rate of regeneration of CFU‐S and on the numbers of mature myeloid cells in the marrow.On the basis of these results it is tempting to speculate that injection of spleen extracts and of fetuin primarily cause a rapid depletion of the marrow's granulocyte reserve. This in turn releases the precursor cell compartment from the inhibitory effects of cell–cell interaction and results in an acceleration of the rate of CFU‐S regeneration.It is equally plausible that factors present in spleen extract and in fetuin cause a depletion of the marrow granulocyte reserve and, by an unrelated mechanism, directly accelerate the rate of regeneration of CFU‐S.
CELL POPULATION GROWTH IN THE CASTRATE MOUSE PROSTATE COMPLEX: EXPERIMENTAL VERIFICATION OF COMPUTER SIMULATION
Authors: Alison Malcolm R. , Appleton David R. , Morley Adrian R. , Wright Nicholas A. 
Published: May 2008

ABSTRACTThe stimulatory action of androgen on cell proliferation in the castrate mouse seminal vesicle and coagulating gland has been studied by DNA measurements in mice 14 days after castration. 100 hr after continuous androgen treatment the level of DNA had increased 2.5‐fold in the seminal vesicle and coagulating gland compared with 14 days castrated controls. A mathematical model predicted this new experimental data when the parameters employed in the simulation were constrained by the results of previous experiments.
DIFFERENT ACTION OF SUICIDAL DOSES OF TRITIATED THYMIDINE AND HYDROXYUREA ON MURINE HAEMOPOIETIC CELLS
Authors: Schreml W. , Bock O. , Bock E. , Heit W. , Kubanek B. 
Published: May 2008

ABSTRACTIn order to gather information on the factors that cause the different action of suicidal doses of tritiated thymidine (3H‐TdR) and of hydroxyurea on murine stem cells, the incorporation of 3H‐TdR into DNA of bone marrow and spleen cells has been studied. Continuous death of labelled cells after suicidal 3H‐TdR is indicated by a more pronounced decline of total DNA‐bound radioactivity in bone marrow and spleen cells compared to that in control animals which had received tracer doses of 3H‐TdR. Extensive and rapid loss of DNA‐bound radioactivity occurred in 3H‐TdR labelled animals after hydroxyurea treatment indicating an instantaneous and highly effective killing of labelled cells. After double labelling of DNA with 3H‐TdR and 125iodo‐deoxyuridine (125I‐UdR), the decline of the ratio of DNA‐bound 125I to DNA‐bound 3H after suicidal 3H‐TdR indicates prolonged tritium reutilization. Following hydroxyurea, reutilization was completed within the first 12 hr after drug administration. These findings explain in part the slow recovery of different stem cell compartments after suicidal 3H‐TdR on the basis of protracted tritium reutilization as compared to the fast recovery which follows the rapid action of hydroxyurea.
EFFECT OF VILLUS LENGTH ON CELL PROLIFERATION AND MIGRATION IN SMALL INTESTINAL EPITHELIUM
Authors: Rijke R. P. C. , Meer‐Fieggen W. van der , Galjaard H. 
Published: May 2008

ABSTRACTFor the interpretation of data supporting the hypothesis of a feedback regulation of proliferative activity in intestinal crypts by the functional villus cell compartment the life span and migration rate of epithelial cells on villi of experimentally reduced length should be known. Autoradiographic studies and scintillation counting of isolated villi at different time intervals after 3H‐thymidine labelling were carried out 36, 48 and 60 hr intervals after X‐irradiation. The results showed that the life span of epithelial cells in rat small intestine (36–48 hr) is independent of the villus length. In villi of reduced length the migration rate of the epithelial cells was found to be decreased compared with controls. Changes in the migration rate in turn seem to be dependent on the production of epithelial cells in the crypt. Comparative studies on the recovery of crypt and villus epithelium after various doses (300 and 700 R) of X‐radiation support the hypothesis that increased proliferative activity in the crypt cell compartment is related to a reduction of the number of functional villus cells below a critical villus length. The importance of these findings in the interpretation of data on (micro) biochemical analyses of certain cell differentiation characteristics during increased proliferative activity is discussed.
3H‐5‐IODO‐2′‐DEOXYURIDINE TOXICITY PROBLEMS IN CELL PROLIFERATION STUDIES
Authors: Dethlefsen Lyle A. 
Published: May 2008

ABSTRACTThe toxicity of 3H‐5‐iodo‐2′‐deoxyuridine (3H‐IUdR) was evaluated by injecting tumor‐bearing C3H mice with different concentrations of ethanol (the solvent), different doses of tritium tagged onto either IUdR or thymidine and different chemical doses of IUdR, and then measuring the 3H‐IUdR incorporation into duodenal and mammary tumor DNA as well as the cellular kinetics of duodenal crypt cells. Ethanol (37% or less, 0.2 ml/mouse) does not significantly inhibit IUdR incorporation into DNA, and the incorporation after a tritium dose of 75 μCi 3H‐IUdR/mouse (about 3 μCi/g body weight) is not less than the incorporation following an injection of 25 μCi 3H‐IUdR/mouse when the IUdR dose is below 0.005 μmole per mouse. The toxic effects are primarily due to chemical toxicity from IUdR per se. IUdR, at doses of 0.2 μmoles per mouse does inhibit IUdR incorporation into duodenal and tumor DNA, and the duodenal labeling index and the fraction of labeled mitoses are significantly reduced when 0.013 μmole IUdR per mouse is injected. Also some of the duodenal cells containing IUdR apparently undergo only one post‐labeling division and the generation time (Tc) of the cells containing IUdR (25 μCi 3H‐IUdR/mouse) is 15.3 hr as compared to 13.3 hr for cells labeled with 3H‐T (75 μCi/mouse). This increase in Tc is probably not statistically significant; nevertheless, these results do indicate that one must be exceedingly cautious when using 3H‐IUdR as a radiotracer for studies concerned with in vivo cellular kinetics and, at least for C3H mice, the dose should be less than 0.01 μmole per 25 g mouse.
VARIATIONS OF MITOSIS‐INHIBITING CHALONE ACTIVITY IN EPIDERMIS AND DERMIS AFTER CARCINOGEN TREATMENT
Authors: Rohrbach R. , Laerum O. D. 
Published: May 2008

ABSTRACTDuring regeneration and hyperplasia following a single application of a carcinogen to mouse epidermis, the rate of epidermal cell proliferation varied inversely with the content of mitosis‐inhibiting activity (chalone). The main inhibitory activity was present within the epidermal cells, but a lesser activity was also found in the corresponding extracts of dermis. This supports the concept that chalones act as physiological regulators of cellular proliferation under pathological as well as normal conditions. The possibility that the dermis also takes an active part in this regulation is discussed.
THE KINETICS OF 51,Cr RELEASE FROM TARGET CELLS IN CELL MEDIATED CYTOTOXICITY AND THE RELATIONSHIP TO THE KINETICS OF KILLING
Authors: Sanderson Colin J. , Taylor Geoffrey A. 
Published: May 2008

AbstractThe kinetics of T‐cell mediated cytotoxicity (CMC) have been re‐examined. It is clear that per cent 51Cr release is linearly related to effector cell number and not to its log as often suggested. Data are presented showing that killing can occur within 1 min of lymphocyte‐target cell contact and that 51Cr is released rapidly from killed cells. Inactivation experiments aimed to stop ongoing cytolysis indicate that all target cells are brought into contact with effector lymphocytes within 45 min. At a ratio of 50:1 the kinetics of contact resemble saturation kinetics, indicating a number of effector cells similar to or in excess of the number of target cells (that is, at least 2 % of total lymphocytes). Although CMC is causally related to cell contact, it is chronometrically unrelated and occurs as a random reaction (that is it can occur immediately or up to hours later than contact). The mean time depends on the number of effector cells.The killing reaction is temperature dependent and proportional to the number of effector cells but does not depend on the intact effector cell. An intact effector cell is only required to bring about contact. It is suggested that this final cytolytic event is brought about by the target cell itself, perhaps as a result of attempts to free itself from the attached lymphocyte.
RECOVERY OF PROLIFERATING HAEMOPOIETIC PROGENITOR CELLS AFTER KILLING BY HYDROXYUREA
Authors: Hodgson G. S. , Bradley T. R. , Martin R. F. , Sumner M. , Fry P. 
Published: May 2008

AbstractTwo doses of 1 mg/g of hydroxyurea (HU), injected 7 hr apart into irradiated mice in which CFU‐S were proliferating during marrow regeneration, killed about 90% of CFU‐S. This same dose regime injected into normal female mice, with non‐proliferating CFU‐S killed 92 % of CFU‐C, 99 % of ESC and only 30 % of CFU‐S. One day after the treatment CFU‐S had decreased to 50 % and remained at about this level for a further day then returned to normal values. In spleen the increase in CFU‐S was delayed by a day and showed a marked overshoot. During the period that CFU‐S were decreased in number they were actively proliferating. Marrow CFU‐C recovered in an exponential manner with a doubling time of 16 hr. Spleen CFU‐C recovered 1 day later than marrow and showed a pronounced overshoot. ESC recovered very rapidly with doubling time of 5 hr. The changes in 59Fe incorporation into RBC, and the peripheral blood picture, were a delayed reflection of the changes in ESC and CFU‐C.
DURATION OF MITOSIS AND SEPARATE MITOTIC PHASES COMPARED TO NUCLEAR DNA CONTENT IN ERYTHROBLASTS OF FOUR VERTEBRATES
Authors: Grosset Lise , Odartchenko Nicolas 
Published: May 2008

AbstractThe passage of a wave of tritiated. thymidine‐labelled cells through each of the phases of mitosis is analysed in erythroblasts of four vertebrates species, selected because of their widely differing diploid DNA content. Mitotic time (tm) and relative durations of separate mitotic phases as well as that of the G2 period are thus accurately determined. Mean duration of tm appears to vary according to the species specific DNA amount. This relation is approximately the same as for S, for G1 and for the generation time, which have been previously determined.
FISSION OF CRYPTS IN THE SMALL INTESTINE OF THE IRRADIATED MOUSE
Authors: Cairnie A. B. , Millen B. H. 
Published: May 2008

AbstractFollowing 1600 R of X‐rays there was a reduction in the number of crypts in the small intestine of the mouse by 77% as measured 5 days later. However, by 21 days the number had increased steadily to levels approaching normal. The number of villi did not change following irradiation. The mechanism of increase in crypt number was by budding and fission of repopulated crypts which had become larger than normal. Some aspects of crypt organization are discussed.
NEURAL STIMULATION OF MITOTIC ACTIVITY IN THE CRYPTS OF LIEBERKÜHN IN RAT JEJUNUM
Authors: Tutton P. J. M. 
Published: May 2008

AbstractThe influence of nerve stimulation and sham‐stimulation on the mitotic rate in epithelial cells lining the crypts of Lieberkühn in the jejunum of anaesthetized rats was studied.Administration of the anaesthetic and opening the abdominal cavity was without significant effect on the crypt cell mitotic rate. However, externalizing a loop of jejunum and applying sham‐stimuli to its mesenteric nerves resulted in a significant decrease in the crypt cell mitotic rate in that loop. Application of electrical stimuli to the mesenteric nerves of another externalized jejunal loop resulted in a significant increase in the mitotic rate in the crypt cells of that segment. Similar acceleration of crypt cell proliferation by electrical stimuli applied to mesenteric nerves was also seen in chemically sympathectomized rats.