bluuebunny/crossref_metadata_2025_split huggingface dataset:
DNA TURNOVER AND THYMIDINE RE‐UTILIZATION IN MOUSE TISSUES
Authors: Myers D. K. , Feinendegen L. E. 
Published: May 2008

AbstractMice were injected intravenously with tritiated thymidine (TdR) and 125I‐labeled iododeoxyuridine (IUdR) in low doses to provide a simultaneous labeling of tissue DNA with non‐toxic amounts of these two precursors. The total activity per organ and the ratio of the two isotopes was measured in the DNA at various times between 1 and 15 days after the injection. Since TdR from dying cells is re‐utilized more efficiently than IUdR from the same cells, more labeled TdR than IUdR was retained in the tissue DNA in these experiments. From the slopes of the regression lines, the true rate of turnover of replicating tissue DNA and the per cent re‐utilization of TdR were calculated. Re‐utilization of TdR varied from 37 to 60 % in the six tissues examined.
THE INFLUENCE OF DIETARY PROTEIN DEFICIENCY ON HAEMOPOIETIC CELLS IN THE MOUSE
Authors: Bell R. G. , Hazell L. A. , Sheridan J. W. 
Published: May 2008

AbstractThese experiments examined the effect of a diet limited only in protein (4% by weight) on haemopoietic stem cells in mice. This diet places severe restrictions on growth and cell proliferation and this was reflected in lower numbers of colony forming units (CFUs) and in vitro colony forming cells (CFCs). Differences were apparent in the response of different organs to this stress; for instance, the incidence of spleen CFUs fell sharply from around 40/mg spleen tissue to 1 ‐4/mg spleen tissue after 3 weeks on a low protein diet. This selective loss did not occur in bone marrow where total CFUs remained proportional to cellular content. Yet a third pattern was shown by thymus CFUs–although the numbers were low these increased from 16/thymus in normal mice to 132/thymus in deprived mice. This was the only organ examined which showed an increase.The effects of a return to a high protein (18 %) diet showed that the spleen was the most responsive organ. By day 5 after the return to 18% protein the spleen contained as many CFUs per million cells as the bone marrow. During this time the content of CFU in the spleen had increased some 50‐fold whereas bone marrow CFUs only doubled. The spleen assumes the major reconstitutive role during the refeeding process.
THE MIGRATION OF LYMPHOCYTES ACROSS SPECIALIZED VASCULAR ENDOTHELIUM
Authors: Ford W. L. , Sedgley M. , Sparshott S. M. , Smith M. E. 
Published: May 2008

AbstractLymphocytes were exposed in vitro to either trypsin or neuraminidase. The ability of the treated cells to migrate into tissues was measured (a) by i.v. injection into intact recipients and (b) by vascular perfusion through an isolated lymph‐node preparation. The localization of trypsinized cells in the lymph‐nodes of recipients was deficient when compared to untreated lymphocytes and there was a surplus of trypsinized cells in the blood. Trypsinized cells migrated into the isolated nodes in reduced numbers. By contrast, neuraminidase treated lymphocytes were markedly deficient in the blood of recipients early after injection; their localization in the spleen and lymph‐nodes was also deficient but they were in surplus in the liver. Moreover they migrated into the isolated nodes in slightly increased numbers. By 24 hr after injection the perturbed localization pattern produced by either enzyme was partly restored to normal. In conclusion, trypsin interfered with the capacity of lymphocytes to migrate into lymph‐nodes but neuraminidase did not; the latter promoted the hepatic sequestration of cells and the reduced localization in the blood and tissues was a consequence of this. The hypothesis that lymphocytes adhere to specialized endothelia in lymph‐nodes because of specific glycoside sequences on their surface lacks experimental support.
THE EFFECTS OF COLCEMID ON MOUSE BONE MARROW
Authors: Shackney Stanley E. , Bunn Paul A. , Ford Sharon S. 
Published: May 2008

AbstractFollowing Colcemid administration, mitoses accumulate preferentially in the subendosteal region of the bone marrow of the mouse. This finding suggests that the most rapidly proliferating cells are localized to the subendosteal region, and complements previous radioautographic studies which have demonstrated a corresponding labelling gradient in the marrow. Quantitative estimates of cell cycle time by the stathmokinetic method were precluded by the presence of significant Colcemid induced interphase cell loss. Colcemid also affected cell differentiation in the marrow. Following Colcemid administration there was a fall in mature granulocytes in the marrow, and a concommitant rise in marrow megakaryocytes.
CELL CYCLE KINETICS IN AN IN VITRO TUMOR MODEL
Authors: Durand RalphE. 
Published: May 2008

AbstractCell cycle kinetic parameters of multicell spheroids in vitro have been estimated using thymidine labeling techniques and autoradiography. Both the mitotic index and thymidine labeling index decreased in larger spheroids, whereas the duration of the cell cycle, as determined by two independent methods utilizing labeled mitoses or labeled cells, was essentially independent of spheroid size or age. These results suggest that the tumor‐like growth exhibited by spheroids is the result of a decreasing growth fraction and a large apparent cell loss, rather than a general elongation of the cell cycle.
INNER ENAMEL EPITHELIUM CELL PRODUCTION RATES
Authors: Bar‐Lev Moshe , Zajicek Gershom , Michaeli Yael , Weinreb Max M. 
Published: May 2008

AbstractCrowning of all four rat incisors slows down their eruption rate, leading to a diminution of cell production by the inner enamel epithelium (IEE). The production rate by 100 progenitor cells is dominated as production rate %. The normal IEE in rats weighing 200 g produces daily 67 cells %. In the crowned incisor this rate drops to 15 cells % while during accelerated eruption the IEE produces daily 152 cells %. In all three conditions the ratio between eruption rate and IEE cell production rate remains unchanged and an eruption of 6.4 μm reflects a production of 1 cell % by the IEE.A method which relates labelled cell displacement along the IEE with its cell production rate is described and its applicability to other cell renewal systems discussed.
HYDROXYUREA: USE IN DETERMINING THE DURATION OF G2 IN TETRAHYMENA
Authors: WORTHINGTON D. H. , NACHTWEY D. S. 
Published: May 2008

AbstractObservation of division of individual cells in microdrops, plus autoradiographic studies using tritiated thymidine and standard cell cycle analysis techniques, reveal that hydroxyurea (10 DIM) reversibly arrests the normal progression of exponentially growing Tetrahymena pyriformis through the initial 92 % of S‐phase while not affecting cells in the terminal 8 % and in G2 and division. Thus the fraction of the population of cells that is in G2 can be approximately determined by the fraction of the population able to divide in the presence of hydroxyurea. This fraction can be related to the approximate duration of G2 by calculations which compensate for the age gradient.
AUTORADIOGRAPHIC STUDY OF TYPE II‐CELL HYPERPLASIA IN LUNGS OF MICE CHRONICALL EXPOSED TO URETHANE
Authors: Kauffman Shirley L. 
Published: May 2008

AbstractHyperplasia of pulmonary alveolar epithelium was induced by exposure of adult mice to 0–1% urethane in drinking water, and their lungs were analysed using combined autoradiographic and morphometric methods. The response of pulmonary epithelium showed three phases: an initial one of 3 weeks in which the number of type II cells was consistently low and, after a transient decrease in 3H‐thymidine labeling index, the latter steadily increased. Degenerating or dead type II cells were found, consequently this period was considered one in which cell death was disproportionately increased over cell production. Between the 3rd and 6th weeks the number of type II cells doubled, and thereafter increased at a slower rate. The 3H‐thymidine labeling index reached its peak at 6 weeks. The third phase was marked by a decline in labeling index which returned to near‐normal levels by the 16th week. The number of type II cells declined slowly after the 10th week and was still elevated at the end of the observation period. Tumors consisting of type II cells continued to arise even during the period of declining labeling index.The dissociation between the proliferative response which was reversible, and the neoplastic response which was not, supports the assumption that the major part of the observed population growth or hyperplasia induced by urethane was a form of regeneration repair secondary to cell death and may be unrelated to tumor growth.
A STABLE ISOTOPE METHOD FOR MEASUREMENT OF THYMIDINE INCORPORATION INTO DNA
Authors: Heck Henry d'A. , McReynolds James H. , Anbar Michael 
Published: May 2008

ABSTRACTA method has been developed for the measurement of DNA synthesis in vivo using the incorporation of multilabeled, non‐radioactive thymidine. Simultaneous intraperitoneal injection of hexalabeled thymidine and tritiated thymidine into a normal adult rat resulted in the incorporation of both labeled nucleosides into the DNA of cells undergoing replication. The DNA of several tissues and organs was analysed, including liver, thymus, spleen, bone marrow, and small intestine. Following extraction with hot trichloroacetic acid, acid hydrolysis, and thin‐layer chromatography of the hydrolysates, the isotopic compositions of the thymine products were determined by field ionization mass spectrometry and by scintillation counting. The relative incorporation of radioactive and stable isotope‐labeled thymidine was similar in all tissues, and corresponded to the ratio of the two labeled nucleosides in the injected material. These results indicate the feasibility of utilizing thymidine multilabeled with stable isotopes for measurement of cellular proliferation rates in conjunction with cancer therapy.
THE APPLICATION OF AGE DISTRIBUTION THEORY IN THE ANALYSIS OF CYTOFLUORIMETRIC DNA HISTOGRAM DATA
Authors: Watson James V. 
Published: May 2008

ABSTRACTAge distribution theory has been employed in a model to analyse a variety of histograms of the DNA content of single cells in samples from experimental tumours growing in tissue culture. The method has produced satisfactory correspondence with the experimental data in which there was a wide variation in the proportions of cells in the intermitotic phases, and generally good agreement between the 3H‐thymidine labelling index and the computed proportion in S phase. The model has the capacity to analyse data from populations which contain a proportion of non‐cycling cells. However, it is concluded that reliable results for the growth fraction and also for the relative durations of the intermitotic phase times cannot be obtained for the data reported here from the DNA histograms alone. To obtain reliable estimates of the growth fraction the relative durations of the phase times must be known, and conversely, reliable estimates of the relative phase durations can only be obtained if the growth fraction is known.
CYTOKINETICS OF RAT TRACHEAL EPITHELIUM STIMULATED BY MECHANICAL TRAUMA
Authors: Gordon Ronald E. , Lane Bernard P. 
Published: May 2008

ABSTRACTMild abrasion of rat tracheal epithelium results in irreversible damage to the superficial cells and stimulates the viable basal cells to participate in a nearly synchronous wave of DNA synthesis and mitosis. For the growth population as a whole, DNA synthesis started at 14 hr after injury and persisted for 16 hr. The duration of S in individual cells was determined autoradiographically by identifying the time at which a second pulse of DNA precursor (14C‐TdR) was no longer incorporated by cells labelled with 3H‐TdR at the onset of S. S was found to be 8–9 hr long. It was also determined that cells entering S at later times synthesized DNA for the same 8–9 hr period. TG2 was calculated to be 21/2–31/2 hr by subtraction of Ts and 1/2TM from the period from onset of DNA synthesis to metaphase. By making a second denuding lesion adjacent to the first injury, the cells were stimulated through at least another period of S. At the peak of the second wave of DNA synthesis (50 hr after injury) 14C‐TdR was present in the same cells which had incorporated 3H‐TdR administered at the mid‐point of the preceding synthetic phase. The 28‐hr interval between these two peaks of synthesis is the measure of cell cycle duration for these regenerating tracheal epithelial cells.
FASTING AND REFEEDING: CELL KINETIC RESPONSE OF JEJUNUM, ILEUM AND COLON
Authors: Hagemann Ronald F. , Stragand James J. 
Published: May 2008

ABSTRACTFollowing a period of fasting, feeding a normal diet results in a burst of DNA synthesis in the crypts of the colonic epithelium. This is due largely to a prompt entry of cells, blocked in G1, into S. Peak levels of S cellularity exceed 4 times the fasting, and 2 times the normal fed, control values. Refeeding a low residue diet (soluble casein, glucose and corn oil) results in a return to control levels of proliferative activity, but no hyperplasia.However, in jejunum and ileum, refeeding is followed by a return to near control levels of proliferation with only a slight overshoot in S phase cellularity.During the fasting period, the ileal crypt proliferative compartment (Pc‐zone) and total crypt cellularity decline significantly. These changes are accompanied by an increase in the total cycle time, due to an equivalent lengthening of the G1 and S phases. Following refeeding, there is a reduction in the cycle time and a gradual return to the control values for the Pc‐zone size and cellularity.In the colon, fasting has no effect on the Pc‐zone size or total crypt cellularity. There is an approximate doubling of the cycle time due solely to an increase in G1. Following refeeding there is an increase in the Pc‐zone size and crypt cellularity and a marked shortening of the cycle time.Evidence that a G1 cycle blockade is induced in the colon by fasting is given by a lengthening of the G1 period and by stathmokinetic studies employing vincristine.
PROLIFERATION OF ERYTHROID AND GRANULOCYTE PROGENITORS IN THE SPLEEN AS A FUNCTION OF STEM CELL DOSE
Authors: Hasthorpe S. , Hodgson G. 
Published: May 2008

ABSTRACTA study of the kinetics of cellular proliferation, in the morphologically unrecognizable haemopoietic progenitor cell compartment, as a function of injected CFU‐S dose has been carried out in the spleens of lethally X‐irradiated mice using 3H‐TdR labelling. Amplification in this proliferating cell compartment was observed to decline as CFU‐S dose increased. The number of divisions in the differentiated line arising from CFU‐S up to the first appearance of recognizable erythroid precursors were calculated to be 9.2, 12.5, 15 and 17 for the 2, 0.35, 0.05 and 0.007 femur equivalent doses respectively. The growth of cell populations arising from CFU‐S was biphasic, with a rapid initial phase having a doubling time of about 6.3 hr, and a slow phase of doubling time around 1 day. Analysis of the rapid phase by the FLM method gave a cycle time of 5.6 hr. Recognizable labelled erythroid precursors were detected at the same time as, or just after, the change in slope of the growth curve. Significant numbers of proliferating (labelled) granulocytes only appeared in the spleens of animals receiving the higher marrow doses (2 and 0.35 femur). The erythroid to granulocyte ratio was also a decreasing function of marrow dose.
FATE OF THYMOCYTES: STUDIES WITH 125I‐IODODEOXYURIDINE AND 3H‐THYMIDINE IN MICE
Authors: Joel D. D. , Chanana A. D. , Cottier H. , Cronkite E. P. , Laissue J. A. 
Published: May 2008

ABSTRACTCortical thymocytes of young adult mice were labeled in situ with radioactive DNA precursors. As a result of cell emigration and cell death, total thymic radioactivity decreased within 8 days to 10% or less of that present on day 1. Accumulation of thymic migrants in peripheral lymphoid organs was estimated by computing the net thymus‐derived radioactivity in these tissues. Thymic cell death was assessed by comparing values obtained with 125I‐UdR to those acquired with 3H‐TdR. The results indicate that cortical thymocytes migrate to the spleen, mesenteric lymph node, femurs and intestine; nevertheless, only a small fraction of the activity originally present in the thymus was recovered in these organs; the vast majority of newly formed cortical thymocytes apparently die after a relatively short life span. Exclusive of the fraction which dies in situ, evidence for thymocyte death is seen in bone marrow; however, most migrants appear to terminate in the intestine.
NUCLEIC ACID CONTENT OF HeLa S3 CELLS DURING THE CELL CYCLE: VARIATIONS BETWEEN CYCLES
Authors: Thilly W. G. , Arkin D. I. , Wogan G. N. 
Published: May 2008

ABSTRACTThe process of continuous resynchronization with excess thymidine provides sufficient cell material for accurate chemical determination of DNA and RNA in HeLa S3 cells at hourly intervals during the cell cycle. Total DNA is constant during the non‐S phase portion of the cell cycle but varies widely among cycles of synchronous growth. Total cellular RNA content increases linearly in the G1 phase and accelerates to a higher linear rate of accumulation, which remains constant during most of the S and G2 phases. The ratios of early and late cycle rates of RNA accumulation are not constant among cycles.
PROPERTIES OF THE H‐4‐II‐E TUMOR CELL SYSTEM
Authors: Evans M. J. , Kovacs C. J. 
Published: May 2008

ABSTRACTGrowth and cell proliferation kinetics of hepatoma H‐4‐II‐E and its tissue culture derivative have been studied to establish the characteristics of an in vivo—in vitro solid tumor model. The H‐4‐II‐E line, originating from the Reuber H‐35 hepatoma, can be maintained and studied either in cell culture or as a transplantable solid tumor in ACI male rats. In addition it allows for the in vitro assay of cell survival following treatment of animal tumors in situ. In vivo, hepatoma H‐4‐II‐E is a rapidly growing tumor with a mean doubling time of 49.2 hr. The cell cycle time is 39.1 hr with a cell loss factor of 0.32. Retrospective examination of tumor specimens obtained during the establishment of the H‐4‐II‐E tumor system demonstrates that both structural as well as cell population changes have occurred. The biological characteristics of the primary tumor (H‐35) and an early intermediate stage (H‐35tc2) are compared with H‐4‐II‐E and the histopathological, growth and cell kinetic changes are discussed.
METHODS FOR DETERMINING THE PROLIFERATION KINETICS OF CELLS BY MEANS OF 5‐BROMODEOXYURIDINE
Authors: Pera F. , Mattias P. , Detzer K. 
Published: May 2008

ABSTRACTAfter treatment of cells with 5‐bromodeoxyuridine (BUdR), the percentage of completely BUdR‐labelled interphase nuclei is greater the longer the BUdR treatment. The labelling effect is visible after staining with the fluorochrome 33258 Hoechst and with Giemsa. Various formulae and a nomogram are presented by means of which the percentage of cells in S period, duration of the S period and the whole cell cycle can be determined by examination of a single preparation or by comparison of several preparations. The methods are tested using cell cultures of Microtus agrestis and compared with autoradiographic methods after labelling with 3H‐thymidine.
THE ROLE OF ERYTHROPOIETIN IN REGULATION OF POPULATION SIZE AND CELL CYCLING OF EARLY AND LATE ERYTHROID PRECURSORS IN MOUSE BONE MARROW
Authors: Iscove N. N. 
Published: May 2008

ABSTRACTThis study was designed to determine the stage in haemopoietic cell differentiation from multipotential stem cells at which erythropoietin becomes physiologically important. The responses of haemopoietic precursor cells were monitored in the bone marrow of mice under conditions of high (after bleeding) and low (after hypertransfusion) ambient erythropoietin levels. The number of relatively mature erythroid precursors (CFU‐E), detected by erythroid colony formation after 2 days of culture, increased three‐fold in marrow by the fourth day after bleeding, and decreased three‐fold after hypertransfusion. Assessed by sensitivity to killing by a brief exposure to tritiated thymidine (3H‐TdR) in vitro, the proliferative activity of CFU‐E was high (75% kill) in untreated and bled animals, and was slightly lower (60% kill) after hypertransfusion. The responses of more primitive erythroid progenitors (BFU‐E), detected by erythroid colony formation after 10 days in culture, presented a contrasting pattern. After hypertransfusion they increased slightly, while little change was noted until the fourth day after bleeding, when they decreased in the marrow. The same response pattern was observed for the progenitors (CFU‐C) detected by granulocyte/macrophage colony formation in culture. The sensitivity of BFU‐E to 3H‐TdR was normally 30%, and neither increased after bleeding nor decreased after hypertransfusion. However, in regenerating marrow the 3H‐TdR sensitivity of BFU‐E increased to 63%, and this increase was not affected by hypertransfusion. These results are interpreted as indicating (1) that physiological levels of erythropoietin do not influence the decision by multipotential haemopoietic stem cells to differentiate along the erythroid pathway as opposed to the granulocyte/macrophage pathway; (2) that early erythroid‐committed progenitors themselves do not respond to these levels of erythropoietin, but rather are subject to regulation by erythropoietin‐independent mechanisms; and (3) that physiological regulation by erythropoietin commences in cells at a stage of maturation intermediate between BFU‐E and CFU‐E.
THE EFFECT OF E TYPE PROSTAGLANDINS ON THE PROLIFERATION OF HAEMOPOIETIC STEM CELLS IN VIVO
Authors: Gidȧli J. , Fehėr I. 
Published: May 2008

ABSTRACTThe ability of protaglandins E1 and E2 to stimulate the proliferation of haemopoietic stem cells (CFUs) was studied in vivo. PGE2, in a dose range of 10‐4 to 10‐1μg/g body weight and PGE1 in a dose range of 10‐5 to 10‐1μg/g body weight, produced a rapid cycling wave of CFUs. The increase in the number of CFUs in S phase was not followed by a rise in the femoral CFUs content, and except for a transient increase in femoral CFUc level, no increase in differentiation was found either. Therefore, it is proposed that haemopoiesis after PG‐induced CFU stimulation is ineffective. PGE2 did not stimulate regeneration of CFUs in a perturbed state (after sublethal irradiation). All these findings support the idea that PGEs might represent potent stimulators of the haemopoietic stem cells acting in physiological doses. However, if acting concurrently with physiological control systems PGs lead to ineffective haemopoiesis (under normal conditions) or do not exert any measurable effect (after sublethal irradiation).
THE EFFECT OF TRANSPOSITION TO JEJUNUM ON EPITHELIAL CELL KINETICS IN AN ILEAL SEGMENT
Authors: Rijke R. P. C. , Hanson W. R. , Plaisier H. M. 
Published: May 2008

ABSTRACTEpithelial cell kinetics were studied in an ileal segment after transposition to proximal jejunum. The number of cells per villus column in the transposed ileum increased after 4‐7 days to reach values normal for jejunum after 14‐30 days. This increase was accompanied by a simultaneous increase in the number of cells per crypt column up to 130% of values in jejunum and ileum in situ. The percentage of labelled crypt cells, after labelling with 3H‐thymidine, and the relative size of the proliferative cell compartment in the crypt in the transposed ileum did not differ from values in the ileum in situ at any time interval after surgery. The total proliferative activity per crypt, which was determined by scintillation counting of isolated crypts after 3H‐thymidine labelling, increased two‐fold from 7 days after surgery. Cell migration studies showed that the increase in the number of villus cells was probably not caused by a change in the life span of the epithelial cells. It seems that the increase in the number of villus cells in ileal epithelium after transposition to proximal jejunum is brought about by an enlargement of the crypt, while the relative size of the proliferative cell compartment in the crypt remains unchanged.