bluuebunny/crossref_metadata_2025_split huggingface dataset:
DEVELOPMENT OF HAEMATOPOIETIC COLONIES ON THE MACROPHAGE LAYER FORMED IN THE PERITONEAL CAVITY OF S1/S1D MICE
Authors: Miyano Y. , Tamai M. , Kitamura Y. 
Published: May 2008

ABSTRACTThe colony‐forming ability of haematopoietic cells was examined on the macrophage layer formed in the peritoneal cavity of S1/S1d mice. the bone marrow cells of the congenic +/+ mice formed many macroscopic colonies on the macrophage layer of the S1/S1d mice although they did not form macroscopic colonies in the spleens of the same S1/S1d recipients. the size and the differentiation pattern of colonies on the macrophage layer of the S1/S1d mice were comparable to those of the colonies on the macrophage layer of the +/+ mice. There are two possible explanations for these results: (a) the microenvironmental defect of the S1/S1d mice has a more prominent effect on the development of spleen colonies than that of macrophage‐layer colonies because ‘Steel’ locus may not be expressed significantly in the peritoneal macrophages or (b) because the cells that make colonies on the macrophage layer may be more differentiated cells than the multipotential stem cells that make colonies in the spleen.
ABILITY OF THYMIC LYMPHOCYTES TO ALTER CFU KINETICS IN RADIATION CHIMERAS
Authors: Shinpock Sarah Garner , Goodman Joan Wright 
Published: May 2008

ABSTRACTIt is known that the poor colony‐forming ability of B6 bone marrow transplanted into B6D2F1 hybrids can be improved if B6 lymphocytes are given in addition. It was recently reported that the augmenting lymphocytes decrease the doubling time of differentiating hemopoietic cells. to determine whether thymus cells alter the self‐renewal of CFUs in this parent F1 combination, retransplan‐tation and 3H‐thymidine ‘suicide’ were employed as methods to determine the cell‐division rate. We have observed that in the presence of thymocytes, parental bone marrow cells are seeded more efficiently in the spleen, and the lag phase of the CFUs growth curve is shortened. However, thymic lymphocytes do not increase the slope of the exponential growth phase of CFUs.
A New Analytical Method For Determining Duration of Phases, Rate of Dna Synthesis and Degree of Synchronization From Flow‐Cytometric Data On Synchronized Cell Populations
Authors: BECK H.‐P. 
Published: May 2008

ABSTRACTL‐cells synchronized by mitotic selection were investigated by flow‐cytometry nd the fractions of cells in the various cell cycle compartments were determined as a function of time. A new analytical evaluation procedure was developed, by which the mean transit‐times of cells through various cell cycle phases can be calculated from these data. Three examples for application of the method are presented: (1) determination of the duration of G1, S, G2+ M and of the whole cell cycle; (2) calculation of the rate of DNA synthesis in several subcompartments of the S‐phase; and (3) evaluation of the degree of synchronization at different stages of the cell cycle.
G2 Sub‐Population In Mouse Liver Induced Into Mitosis By Lead Acetate
Authors: Choie D. D. , Richter G. W. 
Published: May 2008

ABSTRACTA single intracardiac dose of lead acetate (40 μ lead/g body weight) induced a 25‐fold increase in mitosis of mouse hepatocytes 5 hr after injection, as determined by autoradiography. the prompt appearance of a mitotic wave and the relatively large number of mitoses suggest that the mitotic cells were derived from a hepatocyte sub‐population arrested in the G2 phase. the injection of lead also stimulated a small increase in labeled hepatocytes within 6 hr. Analysis of grain counts gave no evidence for unscheduled DNA synthesis. the incremental labeled cells may have originated from a small fraction of the G1 population that was ready to enter the S phase without the usual pre‐synthetic delay.
Growth Fraction and Cycle Duration of Hepatocytes In the Three‐Week‐Old Rat
Authors: Schultze B. , Kellerer A. M. , Grossmann C. , Maurer W. 
Published: May 2008

ABSTRACTThe proliferation of hepatocytes in the liver of 3‐week‐old rats has been investigated by autoradiographic methods. This investigation is a continuation of earlier work on the same topic (Schultze & Maurer, 1972; 1973). 21 days after birth, 102 rats received a single injection of 3H‐TdR. the percentage of labelled mitoses was then determined 1 hr later and at various times throughout the interval up to 12 days after application of 3H‐TdR. In agreement with earlier work, a first peak of labelled mitoses was found 7 hr after 3H‐TdR injection. the area under the peak indicates an S phase duration of 8 hr. In addition a second very broad peak of labelled mitoses was found between 2 and 12 days after pulse labelling. the analysis of the results leads to the conclusion that the hepatocytes of the 3‐week‐old rat have a growth fraction close to 1 and a doubling time of 6–7 days. This is at variance with earlier results of Post, Huang & Hoffman (1963) and Grisham (1969) who had derived a value of 21.5 hr for the duration of the cell cycle and a value of only 0. 1–0.2 for the growth fraction of the hepatocytes.
DEFECT OF ERYTHROPOIESIS IN NON‐LEUKAEMIC AKR MICE
Authors: Legrand E. , Duplan J. F. 
Published: May 2008

ABSTRACTThe kinetics of the CFU population and of erythropoiesis were investigated in the AKR strain mouse prior to the onset of thymic leukaemias: haemopoiesis was compared in syngeneic AKR, semi‐allogenic C3H and (C3H x AKR) F, mice injected with AKR stem cells. These experiments demonstrate that the reduction in the number of spleen colonies previously described by Perkins et al. (1971) in syngeneic hosts, as compared to semi‐allogenic C3H hosts, is actually related to defective erythropoiesis resulting from a dysfunction of the AKR haemopoietic inductive microenvironment (HIM). Erythropoietin secretion is normal in AKR mice. the early haemopoietic events related to the stem cell: lodgement of the CFU (‘f’ factor) and doubling time, are not disturbed, but the onset of CFU proliferation is markedly delayed in the AKR strain. the main expression of the AKR HIM dysfunction is a significant reduction in the number of erythroid (E) colonies and an impaired output of red blood cells per E‐colony in the syngeneic host as compared to the allogenic one. In addition, data indicate that a weakly histo‐incompatible system, such as that in C3H and hybrid hosts, does not interfere with the stages of haemopoiesis except by lengthening the doubling time of the CFU. the results, on the whole, emphasize the prevalent influence of HIM.
ON THE EXISTENCE OF ‘ARRESTED G2 CELLS’ IN MOUSE EPIDERMIS
Authors: Sauerborn R. , Balmain A. , Goerttler K. , Stohr M. 
Published: May 2008

ABSTRACTIt has been postulated that mouse epidermis contains two populations of resting cells, one of which is blocked at the G1‐S boundary and the other between G2 and mitosis. the ‘arrested G2 cells’ were estimated, by the labelled mitosis method, to comprise 510% of the epidermal population and presumed to function as a ‘reserve pool’ which could be activated by wounding. A comprehensive search has now been carried out for arrested G2 cells in mouse epidermis using the direct methods of single cell and flow through cytophotometry. No evidence was obtained which supports the existence of such a cell compartment. Suitable control experiments were carried out to ensure that G2 cells were not lost during the isolation of epidermal nuclei.
LACK of DNA SYNTHESIS INHIBITORY ACTIVITY IN an IMMUNOSUPPRESSOR OBTAINED FROM SPLEEN
Authors: DIATLOFF C. , BENGTSON A. , BILLARDON C. , OELHO A. MACIEIRA‐C 
Published: May 2008

ABSTRACTA tissue extract derived from bovine spleen which is an immunosuppressor in vivo inhibits the incorporation of the two DNA pyrimidine nucleosides but does not inhibit the incorporation of purine nucleosides. the results indicate that the immunosuppressive action of the spleen extract is not mediated via inhibition of cell division.
BISACK ANALYSIS OF THE PHYTOHAEMAGGLUTININ‐INDUCED PROLIFERATION OF HUMAN PERIPHERAL LYMPHOCYTES
Authors: Tice R. , Thorne P. , Schneider E. L. 
Published: May 2008

ABSTRACTThe rate of stimulation as well as subsequent cell cycle duration was examined in phytohaemagglutinin‐stimulated human peripheral lymphocytes grown in vitro in the presence of non‐inhibitory concentrations of bromodeoxyuridine. After incorporation of this heavy atom analogue of thymidine into replicating cellular DNA, it was possible to identify unequivocally metaphase cells which had replicated for one, two and three or more cell cycles. Utilizing this technique, distribution curves were obtained for the appearance of metaphase cells in successive generations, were analysed by a computer simulation model, and the rate of stimulation (4.5% per hr of the remaining unstimulated population) and cell cycle duration (12·3 hr) were determined. The results were compared with those obtained by autoradiography and the possible relationship to the ‘transition probability’ model for cellular proliferation is discussed.
ORGANIZATION OF HAEMOPOIETIC STEM CELLS: THE GENERATION‐AGE HYPOTHESIS
Authors: Rosendaal M. , Hodgson G. S. , Bradley T. R. 
Published: May 2008

ABSTRACTThis paper proposes that the previous division history of each stem cell is one determinant of the functional organization of the haemopoietic stem cell population. Stem cells from a lineage of stem cells which have generated many stem cells (older stem cells) are used in the animal to form blood before stem cells which have generated few stem cells (younger stem cells). The stem cell generating capacity of a lineage of stem cells is finite. After a given number of generations a stem cell is lost to the stem cell compartment by forming two committed precursors of the cell lines. Its part in blood formation is taken by the next oldest stem cell. We have called this proposal the generation‐age hypothesis.Experimental evidence in support of the proposal is presented. We stripped away older stem cells from normal bone marrow and 12 day foetal liver with phase‐specific drugs and revealed a younger population of stem cells whose capacity for stem cell generation was three‐ to four‐fold greater than that of the average normal, untreated population. We aged normal stem cells by continuous irradiation and serial retransplantation and found that their stem cell generative capacity had declined eight‐fold. We measured the stem cell generative capacity of stem cells in the bloodstream. It was a half, to a quarter that of normal bone marrow stem cells and we found a subpopulation of circulating stem cells whose capacity for stem cell generation was an eighth to a fortieth that of normal femoral stem cells. This subpopulation was identified by its failure to express the brain‐associated antigen which was present on 75% of normal femoral stem cells but was not found on their progeny, the committed precursors of granulocytes.
DELAY OF CELL CYCLE PROGRESSION AFTER X‐IRRADIATION OF SYNCHRONIZED POPULATIONS OF HUMAN CELLS (NHIK 3025) IN CULTURE
Authors: Lindmo T. , Pettersen E. O. 
Published: May 2008

ABSTRACTThe effect of X‐irradiation on the cell cycle progression of synchronized populations of the human cell line NHIK 3025 has been studied in terms of the radiation‐induced delay of DNA replication and cell division. Results were obtained by flow cytometric measurement of histograms of cellular DNA content and parallel use of conventional methods for cell cycle analysis, such as pulse labelling with [3H]thymidine and counting of cell numbers. The two sets of methods were generally in good agreement, but the advantages of employing two independent techniques are pointed out.Irradiation was found to have a minor influence on DNA replication. As compared with unirradiated populations, half‐completed DNA replication was 20‐30 min delayed in populations given 580 rad in mid‐G1 or 290 rad in early S.Cell cycle progression was markedly delayed in G2. The sensitivity induction of this delay was 0·6 min/rad for populations irradiated in mid‐G1, and 1·4 min/rad for populations irradiated in early S.
GROWTH OF MOUSE AND HUMAN BONE MARROW IN DIFFUSION CHAMBERS IN MICE
Authors: Niskanen E. , Cline M. J. 
Published: May 2008

ABSTRACTBoth murine and human bone marrow cells were cultured in plasma clots which were formed inside diffusion chambers implanted into cyclophosphamide‐ and saline‐treated mice. After an initial fall, the number of mouse bone marrow cells and numbers of mouse myeloid stem cells (CFU‐C) and agar cluster‐forming units rose faster in the cyclophosphamide‐treated animals. These hosts also favored formation of myeloid (CFU‐D‐G) and erythroid (CFU‐D‐E) colonies and myeloid clusters in the plasma clot. The number and growth rate of mouse CFU‐D‐G were higher than those of CFU‐C from the same marrow population. These observations suggest the existence of humoral factors stimulating granulocyte progenitor cell replication and differentiation. At its best the increment of CFU‐D‐E number was equivalent to that caused by a single 0·1 unit erythropoietin dose.Culture of normal human marrow cells resulted in colonies in the plasma clot containing only granulocytes and macrophages. Cyclophosphamide‐treated host animals were essential for human CFU‐D‐G development. Plating efficiency for human marrow myeloid colonies was better in the conventional in vitro agar cultures than in diffusion chambers.
STUDIES WITH MURINE LPC‐1 PLASMACYTOMA USING [6‐14C]ARGININE
Authors: Humphrey R. L. , Trivedi S. M. , Frondoza Carmelita G. 
Published: May 2008

ABSTRACT[6‐14C]Arginine ([6‐14C]Arg) was used as an in vivo pulse label to study BALB/c murine LPC‐1 plasmacytoma synthesis and secretion of its tumour‐associated M component (IgG2a, k). With this isotope, an eight‐ to ten‐fold enhancement in the labelling of the γ globulin region and ten‐fold reduction in the albumin labelling were observed. Production and secretion of the M component was detected (within 30 min) after cell transfer. Only mice which received tumour cells showed significant labelling in the γ globulin region 24 hr after isotope injection. The labelling behaviour of the tumour M component correlated with the administered cell dose. The peak heights of radioactivity in the γ region increased with increments in cell number. When the percentage radioactivity diverted into M component was plotted as a function of cell dose, a linear relationship was noted. This study demonstrates the feasibility of using [6‐14C]Arg as a tool to follow the newly synthesized tumour‐associated protein, and provides a means of estimating tumour cell number.
DIURNAL VARIATION IN PROLIFERATIVE COMPARTMENTS AND THEIR RELATION TO CRYPTOGENIC CELLS IN THE MOUSE COLON
Authors: Hamilton Elizabeth 
Published: May 2008

ABSTRACTThe depth of the crypts in mouse descending colon varied diurnally, between twenty‐six cells at 24.00 hours and thirty‐eight cells at 12.00 hours. Cell loss from the colon was greatest immediately before the maximum faeces production, at the beginning of the dark period. The labelling index of the colon also changed, from 9% at 20.00 hours to 16% at 12.00 hours. The greatest variation in labelling index occurred at the top of the zone of proliferative cells, between the ninth and eighteenth cell position up the crypt. In this region a synchronized cohort of about forty cells apparently entered S phase once a day. Although the length of the proliferative zone doubled at 12.00 hours, that of the non‐proliferative zone remained fairly constant all day. The number of cryptogenic cells per crypt was estimated by comparing single and split‐dose X‐ray survival curves. This gave a mean value of two cryptogenic cells per crypt. Crypts rarely regenerated from the base after irradiation. The cryptogenic cells probably lay between cell positions Nos 9 and 18 up the crypt and probably did not function as stem cells in the normal crypt.
COLONY‐FORMING UNITS IN DIFFUSION CHAMBERS (CFU‐d) AND COLONY‐FORMING UNITS IN AGAR CULTURE (CFU‐c) OBTAINED FROM NORMAL HUMAN BONE MARROW: A POSSIBLE PARENT–PROGENY RELATIONSHIP
Authors: Jacobsen N. , Broxmeyer H. E. , Grossbard E. , Moore M. A. S. 
Published: May 2008

ABSTRACTA series of experiments was performed to elucidate the relationship between cells that form granulocytic colonies in fibrin clot diffusion chambers implanted into the peritoneum (i.p.) of irradiated mice (CFU‐d) and day 7 and day 14 CFU‐c which give rise to colonies after 7 and 14 days in agar cultures in vitro, respectively.Normal human bone marrow cells were cultured in suspension in vitro or in diffusion chambers implanted into irradiated or non‐irradiated mice. During these culture conditions there was an initial decrease in the number of CFU‐c per culture. This was followed by an increase between day 2 and day 7 of culture. No similar increase of neutrophilic CFU‐d was observed. When CFU‐d, day 14 and day 7 CFU‐c in normal marrow were separated by velocity sedimentation and cultured in suspension culture or in diffusion chambers for 7 days, the maximum increase of day 7 and day 14 CFU‐c was observed in slowly sedimenting cell fractions which contained the majority of CFU‐d. After 3 days in suspension culture, the maximum increase of day 14 CFU‐c was found in fractions which also gave rise to maximum numbers of CFU‐c after 7 days. However, day 7 CFU‐c were found in fractions which initially contained the majority of day 14 CFU‐c. No increase in CFU‐d was found in fractions initially containing peak numbers of CFU‐c. Between 53 and 71% of CFU‐c harvested from diffusion chambers in irradiated mice or from suspension cultures were sensitive to pulse incubation with tritiated thymidine, suggesting that the cells were proliferating during these culture conditions. In diffusion chambers implanted into non‐irradiated mice, however, CFU‐c were found to be relatively resistant to this treatment (3–11% sensitive to tritiated thymidine). Thus marked increases in CFU‐c were also observed during experimental conditions, where no significant DNA synthesis was detected. A reproducible time sequence of increase in CFU‐c populations in culture was observed. Day 14 CFU‐c and cells that gave rise to clusters on day 7 in agar increased between day 2 and day 4, whereas day 7 CFU‐c increased between day 4 and day 7.The results suggested that CFU‐d gave rise to CFU‐c in culture and that day 14 CFU‐c were precursors of day 7 CFU‐c.
CHANGES IN GROWTH KINETICS OF JEJUNAL EPITHELIUM IN MICE MAINTAINED ON AN ELEMENTAL DIET
Authors: Lehnert Shirley 
Published: May 2008

ABSTRACTChanges in the kinetics of the intestinal epithelium were observed in mice maintained on an elemental diet containing hydrolysed protein and medium chain triglycerides. An increase in the length of the villi seen shortly after commencement of the diet was followed by a reduction in the rate of proliferation in the crypt. After 7 days on the diet, an equilibrium state was reached with the cellularity of the villi being 120% that of control while the number of proliferative cells/crypt was reduced by 35%. The proliferative response of the crypt following irradiation occurrred 16 hr later in diet‐fed mice than in controls. It was postulated that, because of the increased cellularity of the villus compartment in diet‐fed mice, additional time was required to reduce the number of villus cells to a critical level at which a proliferative response is induced in the crypt.
A CELL KINETIC MODEL TO EXPLAIN THE TIME OF APPEARANCE OF SKIN REACTION AFTER X‐RAYS OR ULTRAVIOLET LIGHT IRRADIATION
Authors: Al‐Barwari S. E. , Potten C. S. 
Published: May 2008

ABSTRACTSkin reactions to various doses of X‐rays (300 and 10 kV) and ultraviolet light (u.v.) have been compared using hairless mice. Two regions of epidermis with widely differing cell kinetics and gross structure have been compared. Little evidence could be found to support the idea that the early phases of the reaction are dependent on cell cycle time. The data can be explained by a model based on the assumption that epidermis contains only a small fraction of clonogenic (stem) cells and this fraction may vary in different epidermal regions. X‐rays appear to exert their greatest destructive action on these clonogenic cells while u.v. is more indiscriminate in its action, killing both clonogenic and non‐clonogenic cells.
THE ENHANCEMENT OF HAEMOPOIETIC STEM CELL RECOVERY IN IRRADIATED MICE BY PRIOR TREATMENT WITH CYCLOPHOSPHAMIDE
Authors: Blackett N. M. , Aguado M. 
Published: May 2008

ABSTRACTStudies are reported of the enhancement of stem cell recovery following whole body irradiation as a result of prior administration of cyclophosphamide. It is shown that the much larger enhancement of regeneration observed for the hosts own surviving stem cells, compared to the regeneration of injected bone marrow stem cells, is due to the different numbers of stem cells initiating the regeneration in conjunction with the time course of stem cell regeneration.The results show that the environmental changes produced by cyclophosphamide greatly enhance haemopoietic recovery even though at the dose used this agent is relatively toxic to stem cells. Furthermore it has been shown that the level of stem cell regeneration is nearly independent of the γ‐ray dose in the range 3–8 gray (300–800 rad). If human bone marrow should respond similarly it follows that regeneration produced by cytotoxic drugs administered prior to radiation embodies a considerable safety factor as far as recovery of the haemopoietic system is concerned.
TRANSIT TIMES THROUGH THE CYCLE PHASES OF JEJUNAL CRYPT CELLS OF THE MOUSE ANALYSIS IN TERMS OF THE MEAN VALUES AND THE VARIANCES
Authors: Schultze B. , Kellerer A. M. , Maurer W. 
Published: May 2008

ABSTRACTMean transit times as well as variances of the transit times through the individual phases of the cell cycle have been determined for the crypt epithelial cells of the jejunum of the mouse. To achieve this the fraction of labelled mitoses (FLM) technique has been modified by double labelling with [3H] and [14C]thymidine. Mice were given a first injection of [3H]thymidine, and 2 hr later a second injection of [14C]thymidine. This produces a narrow subpopulation of purely 3H‐labelled cells at the beginning of G2‐phase and a corresponding subpopulation of purely 14C‐labelled cells at the beginning of the S‐phase. When these two subpopulations progress through the cell cycle, one obtains FLM waves of purely 3H‐ and purely 14C‐labelled mitoses. These waves have considerably better resolution than the conventional FLM‐curves. From the temporal positions of the observed maxima the mean transit times of the cells through the individual phases of the cycle can be determined. Moreover one obtains from the width of the individual waves the variances of the transit times through the individual phases. It has been found, that the variances of the transit times through successive phases are additive. This indicates that the transit times of cells through successive phases are independently distributed. This statistical independence is an implicit assumption in most of the models applied to the analysis of FLM curves, however there had previously been no experimental support of this assumption. A further result is, that the variance of the transit time through any phase of the cycle is proportional to the mean transit time. This implies that the progress of the crypt epithelial cells is subject to an equal degree of randomness in the various phases of the cycle.
EFFECTS OF INTESTINALLY ABSORBED THYMIDINE ON TRITIATED THYMIDINE UTILIZATION
Authors: Williams R. P. , Cameron I. L. , Adrian E. K. 
Published: May 2008

ABSTRACTExperimental evidence presented suggests that [3H]TdR can be rapidly and efficiently transported from the intestine to the systemic circulation. This pathway for thymidine transport may be physiologically important since administration of cold thymidine in the drinking water enhances the utilization of a parenterally injected dose of [3H]TdR in several body tissues of the mouse.