bluuebunny/crossref_metadata_2025_split huggingface dataset:
KINETICS OF CELL RENEWAL, CELL MIGRATION AND CELL LOSS IN THE HAIRLESS MOUSE DORSAL EPIDERMIS
Authors: Iversen Olav Hilmar , Bjerknes Rolf , Devik Finn 
Published: May 2008

ABSTRACTForty hairless mice were given injections of tritiated thymidine every 4th hour during 10 days. At 24 hr intervals groups of four mice were killed. The numbers of labelled basal and differentiating cells were determined by autoradiography with a stripping film technique. To determine the background activity skin sections from uninjected control mice were subjected to the same stripping film procedure.Another group of hairless mice was given one single pulse labelling with tritiated thymidine. The number of labelled mitoses was scored for 12 hr after the injection. At 10, 12 and 15 hr after the injection, the numbers of labelled basal and differentiating cells were also determined.A mathematical model of cell population kinetics in the epidermis has been suggested. The results of different simulations on this model were compared with the observed results.The curve of mean grain counts under continuous labelling increased from day to day with two well‐defined plateaux.The percentage of all labelled cells increased rapidly up to the 3rd day, and thereafter the curves gradually flattened off. When basal cells and differentiated cells were considered separately the labelling index of the basal cells increased rapidly for the first 3 days and then flattened off at the 100% level on the 5th day.The labelling index of the differentiating cells was low during the first 3–4 days. Then a steep increase in the percentage of labelled differentiating cells was seen, but the curve flattened off again close to the 100 % level after the 7th day. The labelled mitosis curve had its maximum 5 hr after the thymidine injection. The curve fell again to almost zero at 12 hr. Ten, 12 and 15 hr after the injection, 6, 7 and 7% respectively of the labelled cells were found in the spinous layer.It was concluded that three grains over each nucleus could be used as lower limit for considering a cell as labelled. On this basis, tritiated thymidine injections every 4th hour can be considered as continuous labelling.
STUDIES ON LYMPHOCYTES
Authors: Vincent P. C. , Borner G. , Chanana A. D. , Cronkite E. P. , Greenberg M. L. , Joel D. D. , Schiffer L. M. , Stryckmans P. A. 
Published: May 2008

ABSTRACTSome of the time parameters of the cell cycle in bovine thoracic duct lymphocytes have been estimated by analysing labeled mitoses curves, and by double labeling.The two methods gave similar estimates of Ts. Thus, Ts measured directly from labeled mitoses curves varied from 4 to 6 hr, while the estimates from double labeling were 4.8 and 4.5 hr. T
G measured directly from labeled mitoses curves was 5 hr, and estimates of TG from the values of Ts ranged from 6.3 to 7.7 hr.The present data confirm the short generative cycle of large thoracic duct lymphocytes.Extracorporeal irradiation of the lymph (ECIL) had no detectable effect on the cell cycle or the fractional production rate of the lymphocytes. However, the calculated absolute production was reduced following ECIL, due to a decrease in the absolute number of cells present.The grain count over mitoses after ECIL was approximately one‐half that found before ECIL.
INDUCTION OF CELL PROLIFERATION IN THE MOUSE BLADDER BY 4‐ETHYLSULPHONYL‐NAPHTHALENE‐1 ‐SULPHONAMIDE
Authors: Levi Patricia E. , Cowen Diana M. , Cooper E. H. 
Published: May 2008

ABSTRACTThe reaction of the bladder epithelium of mice, following stimulation with a carcinogen, 4‐ethylsulphonylnaphthalene‐1‐sulphonamide (ENS), was studied. A wave of cell division was induced in the resting epithelium, diploid and tetraploid cells being the main dividing elements; some of the high ploidy surface cells also underwent division. The cell cycle time for the diploid and tetraploid cells appeared to be identical. There was considerable variation in the intensity and timing of the onset of cell division in the bladder epithelium of individual animals. ENS caused severe damage to the surface cells of the bladder epithelium as indicated by increased lysosomes and the formation of large vacuoles.
THE ROLE OF STRESS HORMONES IN THE CONTROL OF GRANULOCYTE PRODUCTION
Authors: Rytömaa T. , Kiviniemi Kyllikki 
Published: May 2008

ABSTRACTIt has previously been indicated that the inhibitory power of the granulocytic chalone is not influenced by adrenalin. It is now shown that this is true both in absence and in presence of exogenous hydrocortisone.It is also shown that hydrocortisone itself does not cause significant inhibition of DNA synthesis in rat bone marrow cells in vitro, but that it does act to augment the inhibitory effect which the granulocytic chalone induces.It is suggested that the primary action of hydrocortisone may be on the cell membrane which changes the cell wall permeability to chalone, perhaps by reducing its rate of loss from the cells.
ERYTHROPOIETIC CELL POPULATION CHANGES DURING THE HEPATIC PHASE OF ERYTHROPOIESIS IN THE FOETAL MOUSE
Authors: Paul J. , Conkle D. , Freshney R. I. 
Published: May 2008

ABSTRACTEstimates have been made of the absolute numbers of hepatogenic erythropoietic cells from 12.5 days post fertilization onwards in the mouse. All stages of maturation up to reticulocytes are present in the earliest samples but the least mature cells (proerythroblasts and basophilic erythroblasts) predominate; more mature cells (orthochromatic erythroblasts, reticulocytes and erythrocytes) predominate later in development. The number of hepatogenic haemoglobinized cells increases exponentially with a population doubling time of about 8 hr until about 15.5 days post fertilization. There is then a sharp transition and the doubling time lengthens to about 2 days. The immature cells formed during the rapid phase of increase are poorly haemoglobinized; hence the increase in haemoglobin lags behind that of cells. Calculations of the rates of formation of hepatogenic haemoglobinized cells and haemoglobin per standard number of liver cells show maxima between 15 and 16 days; these findings are in accord with direct observations of rates of haemoglobin synthesis in cultured mouse foetal livers made previously.
BONE MARROW RESTORATION AFTER LOCALIZED DEPLETION
Authors: Maloney Mary A. , Patt Harvey M. 
Published: May 2008

ABSTRACTStudies have been made of marrow restoration after localized depletion of the rabbit femur by dextran perfusion. Restoration was shown to involve an initial period of reorganization which blends with a more prolonged period of hemic cell repopulation. Cellularity returned to normal levels by 35 days, the recovery of myeloid cells being somewhat more rapid than that of the erythroid elements. In either case, the evolution of immature hemic cells was soon followed by the appearance of more mature forms even at the earliest stages of marrow repopulation. 3H‐TdR uptake per cell increased rapidly to a level approximately twice normal after the first week. The augmented incorporation of thymidine, revealed by scintillation spectrometry and confirmed upon autoradiography, was shown to be due to an increase in DNA synthesis rate as well as in the fraction of participating cells. It is suggested that the enhanced cell production is brought about by a decrease in the proliferative cell cycle and an increase in the growth fraction. The origin of the repopulating cells remains a moot point. Cell migration from the epiphyseal marrow is apparently not involved. Irrespective of the source of stem‐type cells, the stimulus for regeneration appears to be locally determined.
PROLIFERATION KINETICS OF AN EXPERIMENTAL ASCITES TUMOUR OF THE MOUSE
Authors: Frindel E. , Valleron A. J. , Vassort F. , Tubiana M. 
Published: May 2008

ABSTRACTThe cell cycles of an experimental ascitic tumour of the C3H mouse (NCTC 2472) were determined at various times after the intraperitoneal injection of 106 cells.It was found that, contrary to results in solid NCTC 2472 tumours, obtained with the same NCTC cells, the duration of the cell cycle and its phases lengthened with the age of the tumour while the growth fraction remained relatively constant. G1 was the first phase to lengthen, while later Ts and TG2 increased also.The amount of DNA per cell was determined by cytospectrophotometry. This method provides data on the evolution during growth of the relative number of cells in each phase of the cell cycle.
ON THE RESTING PERIODS IN THE CELL LIFE CYCLE*
Authors: Epifanova Olga I , Terskikh V. V. 
Published: May 2008

ABSTRACTThe review is concerned with the transition of cells into a specific physiological state—the resting period—in which they may stay for an indefinite time interval without undergoing division or differentiation but retaining both of these potentials. When stimulated such cells may enter into mitotic cycle, divide and differentiate.No direct correlation between the onset of the differentiated state and the transition of cells through the mitotic cycle has been established. It cannot be excluded that sometimes cells may differentiate directly from the resting period. However, there is a large body of evidence that the entry of cells into mitotic cycle is a necessary prerequisite for subsequent differentiation. The susceptibility of cells to differentiative stimuli is retained during the mitotic cycle. The completion of mitosis itself does not imply that a cell will undergo differentiation; in the absence of adequate stimulus it may pass again into a resting period.According to what is known at present it is suggested that cells may pass into a true resting stage not only after completing mitosis but also after doubling their DNA content. It is also conceivable that a cell may pass into a resting period at different stages of its life cycle. The essential feature of the cell life cycle is the alternation of resting periods and periods of active proliferation. This general principle of organization provides conditions necessary for population‐size control, cell differentiation, interaction of a given population with other systems, and the reactions of cells to a changing environment.
THYROID PROLIFERATIVE POTENTIAL AS A FUNCTION OF AGE
Authors: Sheline Glenn E. 
Published: May 2008

ABSTRACTThe effect of a goitrogenic stimulus on thyroid weight and thyroid cell 3HTdR labeling of Sprague‐Dawley rats varying from 2 to 40 weeks of age was determined. Propylthiouracil ad libitum in drinking water produced a spurt in follicle cell labeling index and thyroid weight evident after 24 hr for all age groups. The increase in labeling index reached a peak at 5–7 days and then decreased to a level a few times greater than that of the normal unstimulated thyroid. The tritiated thymidine labeling index for thyroid follicle cells and the effect of PTU thereon was determined for August male rats of 3 days to 12 weeks of age. In the older rats, the follicle cell labeling index rose to 5–6% after 4–5 days of PTU treatment and then slowly fell to about 1%, For the unstimulated control rat of comparable age, the labeling index was about 0.1%. At all ages the thyroid showed a rapid response to PTU. Examination of the time sequence of mitotic labeling showed that the DNA synthesis period was 7.5 hr for normal 2‐week‐old rats and for 10–12‐week‐old rats that had received PTU for 4 days. There was no second wave of labeled mitoses in either group during the 48‐hr interval studied. From the curve of thyroid weight vs time on PTU and from the labeled mitoses curve, inferences regarding the minimum fraction of proliferating follicle cells in the stimulated ‘adult’rat thyroid were made.
ON THE QUESTION OF LONG‐LIVED RNA IN MAMMALS
Authors: Menzies R. A. , Press G. D. , Gold P. H. , Hendley D. D. , Strehler B. L. 
Published: May 2008

ABSTRACTRNA was isolated from various mouse tissues 126 days after the injection of 14C‐uridine and 37 days after the injection of 3H‐uridine. Calculations based on a small but definite residual amount of 14C‐labeled RNA suggest the existence of an RNA with a half‐life in excess of 10 days. Independent calculations based on the ratio of 3H and 14C dpm in chromatographically isolated UMP suggest a minimum half‐life of about 30 days.
AUTORADIOGRAPHIC STUDIES OF EOSINOPHIL KINETICS: EFFECTS OF CORTISOL*
Authors: Andersen Vagn , Bro‐Rasmussen Frede , Hougaard Kjeld 
Published: May 2008

ABSTRACTThe effect of cortisol administration upon the labelling of blood eosinophils was studied in rats given a single injection of 3H‐thymidine. One dose of cortisol did not change the subsequent course of labelling of eosinophils, whereas steroid treatment for 3 days resulted in a delay of the most heavily labelled class. The results seem to indicate that cortisol causes a reversible sequestration of blood eosinophils; and that long‐term steroid administration may delay the release of eosinophils from the bone marrow into the blood.
MEASUREMENT OF THE DURATION OF DNA SYNTHESIS IN ERYTHROID CELLS OF THE BONE MARROW USING A DOUBLE LABELLING AUTORADIOGRAPHIC TECHNIQUE DESIGNED SPECIFICALLY FOR USE WITH HAEMOPOIETIC TISSUES
Authors: Lord B. I. 
Published: May 2008

ABSTRACTThis paper describes a double labelling autoradiographic technique for use with haemopoietic tissues. In involves two photographic emulsions separated by a thin piece of mica on which the cells have been smeared. In this way the autoradiographic grains due to tritium and carbon‐14 appear above and below the cells respectively.Applying the method to bone marrow normoblasts of young rats, the average duration of DNA synthesis (ts) for the pro‐ and early normoblasts taken together is found to be 5.1 hr and the mean cell cycle time (tc) to be 8.2 hr. For the intermediate normoblasts, the corresponding figures are 6.3 hr and 15.7 hr. Average values for all dividing normoblasts in the bone marrow are 5.8 hr and 12.8 hr respectively for ts and tc. The average duration of mitosis is 32 min.
AN EXPERIMENTAL INVESTIGATION OF THE DIVISION PROBABILITY MODEL FOR CELL GROWTH
Authors: Pujara Chandrakant M. , Whitmore Gordon F. 
Published: May 2008

ABSTRACTMouse L cells grown in the presence of BUdR for long periods of time exhibit exponential growth with doubling times which are appreciably longer than the doubling times or generation times of populations not exposed to the drug. The experiments described here indicate that this growth and these long doubling times are not the result of selecting mutant cells resistant to BUdR nor with long generation times. Instead the experimental evidence presented suggests that the growth kinetics can be explained on the basis of the P model. Using this model together with experimental data has made it possible to obtain three independent determinations of the P value for cell populations growing in the presence of various concentrations of BUdR. Within experimental error the three values of P determined for each BUdR concentration are in agreement with one another. Therefore, it is concluded that the division probability model provides an adequate description of the growth properties of L60T cells growing in the presence of BUdR.
A COMPARATIVE STUDY OF THE REPOPULATING POTENTIAL OF GRAFTS FROM VARIOUS HAEMOPOIETIC SOURCES: CFU REPOPULATION
Authors: Schofield R. 
Published: May 2008

ABSTRACTThe growth rate of the CFU populations in spleens and femora has been studied in irradiated mice injected with cell suspensions, containing equivalent number of CFU, from various sources. The doubling times are shown to be dependent upon the source of the cells. Grafts of bone marrow, spleen and foetal liver cells produced doubling times in the spleen of approximately 25, 19 and 16 hr respectively. Grafts of marrow‐derived and spleen‐derived spleen colony cells both gave rise to CFU doubling times lower than those of the corresponding primary grafts (approx. 33 and 26 hr respectively in the spleen). In the case of both bone marrow and spleen grafts the CFU population growth was shown to be independent of the size of the graft. A hypothesis is advanced which invokes at least a dual population of CFU, having different doubling times, different seeding capacities in the haemopoietic tissues following i.v. injection and present in different proportions in the various haemopoietic tissues.
SELECTIVE INHIBITION OF EMBRYONIC DEOXYRIBONUCLEIC ACID SYNTHESIS BY VINBLASTINE
Authors: Williams J. P. G. 
Published: May 2008

ABSTRACTVinblastine inhibits the synthesis of DNA in mouse fetuses in utero, the incorporation of tritiated thymidine into the gut of the parent is, however, not altered. This selective effect, although found with other spindle inhibitors, is not due to the mitotic arresting property of the drug.
EFFECTS OF IRRADIATION ON THE GENERATIVE CYCLE OF THE ESTROGEN STIMULATED VAGINAL EPITHELIUM
Authors: Ladinsky J. L. , Gruchow H. W. 
Published: May 2008

ABSTRACTThe effects of irradiation (300, 500 and 1500 rads) on mitosis and DNA synthesis in the estrogen primed vaginal epithelium have been studied. Dose‐effect relations and the time sequence of effects on the two processes were investigated. The technique of tritiated thymidine labeling of DNA with autoradiography was used, in conjunction with the mitotic count, to study alterations in the generative cycle. Prior to irradiation, ovariectomized female rats were treated daily with diethylstilbestrol for a period of 2 weeks to create a steady state in the vaginal cell population.It was observed that:

Within 1 hr following ionizing radiation, mitotic figures disappear from the population and reappear at a time that is dose dependent. Those cells that have begun mitosis at the time of irradiation were able to complete that phase but no cells which were in G2 were able to begin mitosis. Therefore, a G2 block occurs within 1 hr post‐irradiation.
Radiation reduces the rate of DNA synthesis thus prolonging the S phase. There is no evidence of a radiation‐induced G1 to S block in this system.

Based on these observations, it was further hypothesized that:

Cells in G1 at the time of irradiation are relatively insensitive and continue to progress through the generative cycle at a rate primarily determined by the level of estrogen stimulation.
Radiation may interfere with the estrogen priming mechanism in this hormonedependent system thereby reducing the effective level of estrogen stimulation. This is seen in the behavior of cells which were in G1 at the time of irradiation. The extent of the blockage of estrogen increases with radiation dose and after 1500 rads, estrogen stimulation is essentially at castrate level.
ERYTHROCYTIC CHALONE, A TISSUE‐SPECIFIC INHIBITOR OF CELL PROLIFERATION IN THE ERYTHRON
Authors: Kivilaakso E. , Rytömaa T. 
Published: May 2008

ABSTRACTControl of the rate of cellular proliferation in the erythron seems to be mediated by a tissue‐specific mitotic inhibitor, termed the erythrocytic chalone. the function of this substance seems to be to prevent excessive proliferation of the erythrocyte precursor cells by means of a negative feedback and in terms of peripheral cell numbers.The erythrocytic chalone is present in mature erythrocytes, from which it can be extracted by incubation in a chemically defined medium. It is also present in fresh normal serum and it is possible that in physiological conditions the factor is continuously liberated from mature erythrocytes into the surrounding plasma.In the rat, in an artificially induced polycythaemia the concentration of the chalone in the serum is increased and this increment appears to be the sole cause of the enhanced inhibitory action of polycythaemic serum on the proliferation of the bone marrow cells in vitro.The mode of action of the erythrocytic chalone seems to be to prevent the erythrocyte precursor cells from entering the generative cell cycle; the chalone thus regulates the production of erythrocytes by changing the ‘proliferation efficiency’ in the erythron.So far, nothing is known about the chemical nature of the erythrocytic chalone. However, in gel filtration it is eluted in the same zone as the granulocytic chalone, its molecular weight thus being about 2000‐4000.
CELL PROLIFERATION DURING the COURSE of IMMUNOLOGICAL REJECTION of EHRLICH ASCITES TUMOUR CELLS
Authors: Janik Przemyslaw 
Published: May 2008

ABSTRACTEhrlich ascites tumours were transplanted from their normal hosts (mice) into rats, and studies made of the timing of cell cycle 120‐170 hr after transplantation, when tumour regression was under way. There was no significant change in the duration of the cell cycle. Some increase was found in the average and spread of G2 durations, largely compensated by a decrease in S duration. When taken together with previously published work the results suggest that the immunological pressure of transplantation into a heterologous host prolongs the G2 period.
KINETICS OF THE INNER ENAMEL EPITHELIUM IN THE ADULT RAT INCISOR
Authors: Zajicek Gershom , Bar‐Lev Moshe 
Published: May 2008

ABSTRACTRats were injected with tritiated thymidine and sacrificed at various time intervals up to 24 hr. the extracted incisors were decalcified, cut sagittally, dipped into liquid emulsion exposed for 14 days, developed and stained. the counting consisted of an exact mapping and numbering of the cells.The inner enamel epithelium consists of two compartments: proliferative and mature cells. the first may be further subdivided into blasts and metablasts. Each dividing blast yields one blast and one metablast. the metablasts continue to divide further, at least once, yielding again two metablasts.The kinetic parameters of this population are: generation time 22 hr, synthesis time 4.5 hr, mitotic time 30 min, G2 time 2 hr and G1 time 15 hr. the daily cell production of the proliferative compartment equals its size.
GROWTH HORMONE AND CARTILAGE CELL DIVISION IN HYPOPHYSECTOMIZED RATS
Authors: Kember N. F. 
Published: May 2008

ABSTRACTThe effects of growth hormone on cell division in the growth cartilage of normal and hypophysectomized rats have been studied by autoradiography with tritiated thymidine. Following hypophysectomy the percentage labelling fell to 1.5‐2%, about one fifth of that found in normal animals. Following injection of 100‐1600 μg of bovine growth hormone, the percentage labelling increased after a delay of 8‐16 hr, the delay, the rate of rise and the maximum reached being dose dependent. Single or repeated doses of growth hormone produced no significant change in normal young rats.
GRANULOCYTE DYNAMICS AND THE QUESTION OF INEFFECTIVE GRANULOPOIESIS
Authors: Maloney Mary A. , Patt Harvey M. , Lund John E. 
Published: May 2008

ABSTRACTA simple analysis was developed to compare granulocyte production in marrow with granulocyte turnover in peripheral blood of the dog. the analysis is anchored to the relative number of granulopoietic and erythropoietic cells that are flashlabeled with tritiated thymidine. This provides a convenient measure of relative production rates, since there is little, if any, difference in the duration of the respective DNA synthesis periods. the latter was confirmed in the present work by comparison of myeloid and erythroid cells in respect to (1) labeled mitosis curves and (2) changes in labeling intensity with constant infusion of tritiated thymidine. the ratio of flash‐labeled granulocyte to erythrocyte progenitors was unity (1.02 ± 0.05) in the eight dogs studied, which means that gross production rates were essentially the same. Since net production as revealed by peripheral blood turnover is greater for erythrocytes than for granulocytes, it follows that there must be some ineffective granulopoiesis. This may correspond to over half of the total production. It is suggested that this phenomenon, which apparently occurs in man as well as in dog, could represent an important feature of granulocyte regulation.