bluuebunny/crossref_metadata_2025_split huggingface dataset:
PROLIFERATION KINETICS IN EPITHELIUM OF GUINEA‐PIG COLON
Authors: Sawicki W. , Rowinaski J. 
Published: May 2008

ABSTRACTAutoradiographs of crypts of guinea‐pig colon labelled with 3H‐thymidine were quantitatively analysed. The analysis involved: (a) comparison of proliferation parameters in crypts situated in two well‐defined regions of colonic folds, i.e. in the top and the basal parts of the fold, and (b) comparison of proliferation parameters in the lower and in the upper parts of an individual crypt. The results provide evidence that: (1) Crypts situated in the top region of folds are significantly longer than those situated in the basal region. (2) The duration of cell cycle and its phases is similar in the crypts of the two regions examined. (3) The rate of 3H‐thymidine uptake is higher in the middle than in the initial and final parts of the S phase, and its pattern is the same for the crypts of the two regions of the fold as well as for the parts of the individual crypt. (4) The proliferating pool size is larger in crypts situated in the top than in the basal region of the fold. (5) The proliferating pool size is larger in the lower parts of crypts from each region than in the upper parts.Control of cellular proliferation in the crypt epithelium is considered to operate separately at the level of the individual crypt and at the level of a group of crypts situated in a given region of the colonic wall.
CYTOKINETIC ANALYSIS of SLOWLY PROLIFERATING BONE MARROW CELLS DURING RECOVERY FROM RADIATION INJURY
Authors: Haas R. J. , Bohne F. , Fliedner T. M. 
Published: May 2008

ABSTRACTA continuous administration of tritiated thymidine (3H‐TdR) into pregnant rats results in a complete labelling of the offspring. Further injections with 3H‐TdR for 26 days maintained the 100% labelling. Four weeks after discontinuation of 3H‐TdR application, distinct classes of cytokinetically resting labelled bone marrow cells were detected. These animals received X‐irradiation of the body with 750 R with one leg shielded, or X‐irradiation of one leg with 750 R, or X‐irradiation of one leg with 1500 R. In none of the experiments did the reticular and endothelial cells show indications of destruction or stimulation.In all X‐irradiated parts the small bone marrow lymphocytes decreased their labelling intensity. the same behaviour was seen in the marrow of the shielded leg. After 1500 R to one leg, a subsequent rise of mean grain count was detected after 3 days. No change of the labelling pattern of lymphocytes of other organs could be observed.The behaviour of labelled bone marrow lymphocytes during recovery from radiation injury suggests that these cells play a role in the regenerative process of bone marrow. There may be a migration from shielded areas into X‐irradiated parts if the dose is high enough to prevent efficient endogenous regeneration.
A STUDY ON INEFFECTIVE ERYTHROPOIESIS IN THE DOG
Authors: Odartchenko Nicolas , Cottier Hans , Bond Victor P. 
Published: May 2008

ABSTRACTErythrocytic cell kinetics were studied in normal dog bone marrow, at the transition between younger cells that are able to synthesize DNA, and more mature nucleated normoblasts which have lost this ability. the rate of progression out of the first group was compared to that into the second, after necessary adjustments of group sizes. No significant discrepancy was detected within the limits of resolution of autoradiographic cytokinetic analysis.It is concluded that ‘ineffective’ red cell production in the normal dog, if it occurs at all, can only be very small in quantity.
THE DISTRIBUTION OF CELL GENERATION TIMES
Authors: Kubitschek H. E. 
Published: May 2008

ABSTRACTTwo different distributions of generation times, log‐normal and reciprocal normal, were compared by fitting them to experimental generation time distributions for bacteria, yeast, protozoa, and mammalian cells. In every case, the reciprocal normal distribution gave better agreement, whether the original frequency distributions or their cumulatives were compared. the log‐normal distribution failed to give significant agreement for three of the original distributions. It is concluded that the reciprocal normal distribution of generation times, or more precisely, the truncated normal distribution of generation rates, is consistent with the published data for steady state populations of all kinds of cells that divide by regular binary fission. A model is suggested for this distribution of generation times, associating it with control of transport of materials into the cell, and with linear cell growth.
AN EVALUATION OF RADIOIODINE‐LABELED 5‐IODO‐2′‐DEOXYURIDINE AS A TRACER FOR MEASURING CELL LOSS FROM SOLID TUMORS*
Authors: Dethlefsen Lyle A. 
Published: May 2008

ABSTRACTRadioiodine‐labeled 5‐iodo‐2′‐deoxyuridine (IUdR) has been evaluated as a tracer for measuring cell loss from C3H mouse mammary tumors. This has been accomplished by considering the problems of label specificity, chemical and radiation toxicity, and reutilization; and by comparing the estimate for cell loss, as obtained here, to another independent estimate previously reported for tumors from the same slow‐growing line. 125I‐IUdR is the current tracer of choice for measuring cell loss from undisturbed solid tumors, and this method is simpler and more direct than the combined techniques of autoradiography and volumetric‐growth‐curve analyses. However, the following limitations apply: (1) the tumor DNA must be extracted prior to counting the radioactivity in the DNA, (2) one must be especially concerned with the chemical and radiation toxicity and they should be evaluated in each new situation, and (3) one must realize the potential for low levels of IUdR reutilization even in the undisturbed tumor. In perturbed situations (i.e. chemical or radiation induced killing) this problem may become severe.
THE KINETICS OF GRANULOSA CELLS IN DEVELOPING FOLLICLES IN THE MOUSE OVARY
Authors: Pedersen Torben , Hartmann Niels Rudolph 
Published: May 2008

ABSTRACTThis investigation describes the kinetics of the granulosa cells in medium‐sized follicles type 3b, 4 and 5a in ovaries of 28‐day‐old Bagg mice. the method of labelling with 3H‐thymidine followed by high resolution autoradiography is used in the experimental work, which consist of determining percentage labelled mitosis (PLM‐) and continuous labelling (CL‐) curves. In order to analyse the data by computer two alternative hypotheses A and B are set up. Both include the assumptions of no cell loss, exponential growth and a resting compartment Q. In hypothesis A cells from Q re‐enter the mitotic cycle via the normal DNA‐synthesis compartment Sp. Hypothesis B includes beside compartment Sp a special DNA‐synthesis compartment Sq where only cells from Q are synthesizing DNA, and these cells re‐enter the mitotic cycle via the G2 compartment. the mean transit time in Sq is considered to be longer than the mean transit time in Sq. On the basis of the hypothesis mathematical expressions for the PLM‐ and CL‐curves are obtained, and by means of a computer the theoretical curves are fitted to the experimental values: thereby all relevant cell kinetical parameters are estimated. Hypothesis B seems to give the best fit between the theoretical and experimental curves. the estimated parameters are: mean cycle times, μc= (56.1 hr, 56.1 hr and 22.3 hr for type 3b, 4 and 5a respectively), doubling times, TD= (96.4 hr, 118.6 hr and 59.1 hr) and the proportion of cells in Q, pQ= (0.60, 0.71 and 0.69).
MEDIUM DEPLETION AND CONTACT INHIBITION OF REPLICATION: ABSENCE OF A SPECIFIC INHIBITOR
Authors: Smets L. A. 
Published: May 2008

ABSTRACTThe role of medium exhaustion in the regulation of contact inhibition of growth was studied in 3T3 cells and various other mammalian cell lines. the concept of a diffusable inhibitor which sustains contact inhibition was not supported by the experimental results. Used medium could be restored by dialysis against a fresh one and also by the addition of nutritional constituents of low molecular weight.The growth properties of several mammalian cell lines were studied. the results revealed an inverse correlation between the sensitivity to contact phenomena and the efficiency to utilize nutrients from the medium for replication.
RESPONSE OF THE PREOSTEOBLAST AND STEM CELL OF RAT BONE MARROW TO A LETHAL DOSE OF X‐IRRADIATION OR CYCLOPHOSPHAMIDE
Authors: Amsel Sheldon , Dell Elisabeth S. 
Published: May 2008

ABSTRACTFollowing syngeneic or autotransplantation of hemopoietic tissue to a heterotopic location, bone formation has been observed to occur in the implanted tissue. the characteristics of the cell residing in hemopoietic tissue with bone forming potential (preosteoblast) are unknown. to define some properties of this cell, its response to X‐irradiation and cyclophosphamide (CTX) was compared to the response of the hemopoietic stem cell. Adult, male rats were exposed to 900 R whole body X‐irradiation or 220 mg/kg of intraperitoneal CTX. With either treatment the dose was sufficient to kill the animals by bone marrow failure. At intervals following the X‐irradiation or CTX, hemopoietic tissue was examined for the presence of viable hemopoietic stem cells and preosteoblasts. Following X‐irradiation, viable hemopoietic stem cells and preosteoblasts could not be detected. Following CTX these cells could be detected. It is suggested that in the rat CTX at 220 mg/kg, although causing death by bone marrow failure, does not reduce the population of the preosteoblast or hemopoietic stem cell as effectively as 900 R X‐irradiation.
A COMPARISON OF METAPHASE ARRESTING AGENTS AND TRITIATED THYMIDINE AUTORADIOGRAPHY IN MEASUREMENT OF THE RATE OF ENTRY OF CELLS INTO MITOSIS IN THE CRYPTS OF LIEBERKÜHN OF THE RAT
Authors: Clarke Rufus M. 
Published: May 2008

ABSTRACTThree methods of estimating cell production rate were used: the rate of accumulation of metaphases blocked by Colcemid, or by vinblastine, and the rate of increase of labelled nuclei after administration of tritiated thymidine. These rates were determined for three sites in the small intestine by counts made on whole micro‐dissected crypts, fixed at various times after the administration of the agents.Within the limits of error of the methods, the cell production rate per crypt was the same when measured by each method (35/hr), and showed a slight fall from the proximal to the distal end of the small intestine (36/hr to 33/hr). the advantages and limitations of each method are discussed.
The Effect of Thermal Shock On the Division Cycle of Meristematic Cells
Authors: De La Torre C. , González‐Fernández A. , Giménez‐Martín G. , Léópez‐Sáez J. F. 
Published: May 2008

Abstract. The dynamic adaptation of a meristem to a thermal change from 15 to 35°C has been studied. A gradual drop occurs in the mitotic index during the first 6 hr after the change, while the percentage of prophases drops less steeply. At the same time the phenomenon of nucleolar segregation is observed.By making use of a cell population morphologically differentiated as binucleate (by ‘labelling’ with caffeine), it was possible (a) to prove that prophase is specifically prolonged and (b) to locate a highly thermosensitive segment of interphase, situated in the middle of the S period, and apparently coinciding with the sub‐period S2, described in the same material as characterized by a decrease in the rate of DNA synthesis.The lengthening of prophase and nucleolar segregation resemble the effects produced by drugs which inhibit RNA synthesis.Intermittent thermal shocks are suggested as a possible means for synchronizing the division cycle of plant cells.
EFFECTS OF ACTINOMYCIN D AND PUROMYCIN ON THE CELL PROGRESS FROM M TO G1 AND S STAGES IN CULTURED MOUSE LEUKEMIA L5178Y CELLS
Authors: Doida Y. , Okada S. 
Published: May 2008

Actinomycin D (0.5 μg/ml) did not prevent M stage cells from entering G1 stage, but blocked their progress from G1 to S stage. The position of the block was approximately 1.4 hr before S stage or just after the beginning of G1 stage. Actinomycin D in this concentration also significantly depressed uridine‐3H uptake into G1 stage cells, but did not suppress leucine‐3H uptake by M and G1 cells. This suggests that some proteins may be synthesized in M and G1 stage cells by messenger RNA left over from the previous cell cycle. However, entry of G1 cells into S stage would require synthesis of new messenger RNA near the beginning of G1 stage. Puromycin (10 μg/ml) did not prevent M cells from entering G1 stage, but blocked their progress from G1 to S stage. The site of blockage was about 0.7 hr before S stage or in the first two‐third of G1 stage. This might be the site where the cells synthesize new G1 proteins necessary for entry to S stage.Comparison of sensitivities of G1 and G2 stages to the two antibiotics reveals that the puromycin sensitivity of G1 cells was similar to that of G2 cells, but the actinomycin D sensitivity of G1 was greater than that of G2 cells.
AN ANALYSIS OF BONE MARROW ERYTHROPOIESIS IN THE MOUSE
Authors: Covelli V. , Briganti G. , Silini G. 
Published: May 2008

Following the model of the erythropoietic system developed in the rat by Tarbutt and Blackett, the authors have carried out a kinetic analysis of bone marrow erythropoiesis in the mouse.Using 59Fe labelling techniques the size of the recognizable precursor cells and of the functional cell compartments have been estimated, while the flow‐rate from the unrecognized precursor cells to the recognizable cells and from the latter compartment to the circulating erythrocytes have been evaluated by 55Fe autoradiography.Differences in the kinetic parameters of the erythropoietic mouse bone marrow compared with the rat bone marrow are reported, whose interpretation has required a more detailed analysis of the original model.
THE DISTRIBUTION AND DIFFERENTIATION OF LYMPH‐BORNE IMMUNOBLASTS AFTER INTRAVENOUS INJECTION INTO SYNGENEIC RECIPIENTS
Authors: Hall J. G. , Parry Dilys M. , Smith Marilyn E. 
Published: May 2008

Thoracic duct lymph from inbred, hooded rats was collected 3–5 days after antigenic stimulation of the caudal lymph nodes. During this period the lymph contained 10–15% of large, basophilic lymphoid blast cells (immunoblasts). By incubating the lymph cells at 38.C with radioactive DNA precursors, either 3H‐thymidine or 125I‐deoxyuridine, the immunoblasts became labelled but the small lymphocytes did not. The lymph cells were then washed and injected intravenously into syngeneic recipients which were killed after various intervals up to 24 hr so that the radioactivity of their organs could be assayed by scintillation counting and autoradiography.The main finding was that in animals killed after 4 or more hours the small gut always contained most of the recoverable activity and autoradiographs showed that this was because the injected cells had infiltrated the lamina propria in large numbers. Earlier, many of the injected cells were retained temporarily in the lungs, liver and spleen but many of them soon left those organs and entered the lamina propria of the small gut.An electron microscope study of autoradiographs showed that 24 hr after injection the cells which entered the lamina propria of the gut had differentiated into plasma cells so that they displayed abundant, lamellar endoplasmic reticulum.
VARIATION IN THE DURATION OF MITOSIS IN THE CRYPTS OF LIEBERKUHN OF THE RAT; A CYTOKINETIC STUDY USING VINCRISTINE
Authors: Wright Nicholas , Morley Adrian , Appleton David 
Published: May 2008

The variation in the duration of mitosis (tm) with cell position in the small intestinal crypts of the adult rat has been measured by a stathmokinetic technique using vincristine. The value for the whole crypt column was 0.43 hr, or 26 min. At the bottom of the crypt tm was in excess of 1 hr, but rapidly decreased and throughout the greater part of the proliferative compartment was between 0.40 and 0.50 hr. At the top of the proliferative compartment an increase in tm was demonstrated.If the value of 0.43 hr for the whole crypt column is correct, then one argument for postulating the formation of metabolic DNA during differentiation in the small bowel epithelium of the rat becomes invalid. Variations in tm within the crypt have been shown to increase the values of cell velocity obtained from cumulative birth rate diagrams. Finally further evidence has been presented for the existence of a slowly dividing subpopulation of cells at the base of the crypt. These cells may be important in crypt repopulation after damage with phase specific anti‐tumour drugs.
CELL KINETICS IN DIFFUSION CHAMBERS: SURVIVAL, RESUMPTION OF PROLIFERATION, AND MATURATION RATE OF MURINE HAEMOPOIETIC CELLS
Authors: Benestad Haakon B. 
Published: May 2008

Bone marrow cells and blood leucocytes from mice have been cultured in vivo in diffusion chambers. Granulocytes and macrophages were formed in the chambers, whereas lymphocytes and mature end cells were gradually lost.The proliferation, differentiation and death of cultured cells were quantified by total and differential cell counting, by scintillation counting and by radio‐autographic evaluation of 3H‐thymidine incorporation. Hydroxyurea and vinblastine were used as cytotoxic agents.Ordinarily 40–60% of the cells inoculated could not be recovered after a few hours in culture. Proliferative cells resumed DNA synthesis shortly after implantation, and the rate of synthesis did not decline on further culturing. Steady‐state progenitor cells had a pre‐replicative lag period of about 18 hr, whereas regenerating progenitors started to synthesize DNA after about 14 hr. After 72 hr of culturing newly formed segmented granulocytes were detected. Maturation from the myelocyte to the segmented granulocyte stage lasted about 18 hr. Eosinophilic granulocytes had a long life span in the chambers, whilst the segmented neutrophils were rapidly eliminated after a life span estimated to be about 2 days.
MOBILIZATION OF HAEMOPOIETIC STEM CELLS (CFU) INTO THE PERIPHERAL BLOOD OF THE MOUSE; EFFECTS OF ENDOTOXIN AND OTHER COMPOUNDS
Authors: Vos O. , Buurman W. A. , Ploemacher R. E. 
Published: May 2008

Factors affecting the circulation of haemopoietic stem cells (CFU) in the peripheral blood of mice were investigated. I.v. injection of sublethal doses of endotoxin, trypsin and proteinase appeared to raise the number of CFU per ml blood from about 30–40 to about 300–400 or more within 10 min. The effect was smaller when smaller doses of the substances were injected. After this initial rise the number of circulating cells returned to normal in a few hours. Following endotoxin there was a second rise which started 2–3 days after injection and attained a peak on the 6th–7th day. The first rise is explained as a mobilization of stem cells from their normal microenvironments into the blood stream; the second rise is considered to reflect proliferation of CFUs in the haemopoietic tissues. The spleen seems to be acting as an organ capturing CFUs from the blood and not as a source adding stem cells to the blood.The early mobilization of CFU after endotoxin injection did not coincide with a mobilization of neutrophils. The number of circulating band cells was increased during the first hours.The importance of ‘open sites’in the haemopoietic tissue for capturing CFUs was studied by emptying these sites through a lethal X‐irradiation and injecting normal bone marrow cells. When a greater number of syngeneic bone marrow cells was injected intravenously, the level of circulating CFU in irradiated mice was slightly lower than the level in unirradiated mice during the first hours.
INFLUENCE OF HAIR PLUCKING ON THE TURNOVER TIME OF THE EPIDERMAL BASAL LAYER
Authors: Hamilton Elizabeth , Potten C. S. 
Published: May 2008

The epidermal cell kinetics of male DBA‐2 mice have been studied using tritiated thymidine. Liquid scintillation data from skin punches, taken after stimulation of hair growth by plucking, agree well with similar data from DBA‐1 mice. A technique has been devised for obtaining sheets of epidermal cells from haired mice. Labelling index values from these sheets show that epidermal proliferation increases after plucking and they agree well with values obtained from sections. Counts of cells per unit area of epidermis show that cells are removed by plucking.Using an estimated value for the length of S, the turnover time of the basal layer was calculated. The growth fraction and proliferative cell cycle time have also been estimated.
HYDROXYUREA EFFECTS IN THE C3H MOUSE: I. DUODENAL CRYPT CELL KINETICS
Authors: Dethlefsen Lyle A. , Riley Reba M. 
Published: May 2008

ABSTRACTDuodenal crypt cell kinetics in C3H mice have been studied before and after the injection of a single dose (3 mg/g body weight) of hydroxyurea (HU). This was done by autoradiographic analysis of crypt cells which had been labeled with tritiated 5‐iodo‐2′‐deoxyuridine. This dose of HU kills the cells which are synthesizing DNA at the time of injection, inhibits DNA synthesis completely for 4–5 hr, and causes a partial synchronization of the cells when they recover from the inhibitory effects of HU. Duodenal crypt recovery is manifested by a decrease in the mean cell cycle time, an increase in the proliferating fraction, and a lengthening of the crypts. The acute cellular responses are apparently complete within 24–48 hr, but the length of the crypt has not returned to normal by 48 hr after HU administration.
COMPUTER SUBTRACTION OF BACKGROUND IN AUTORADIOGRAPHY WITH TRITIATED THYMIDINE
Authors: Benassi Marcello , Paoluzi Renato , Bresciani Francesco 
Published: May 2008

ABSTRACTAn iterative method is suggested to estimate true labelling index even when background and experimental (background + true labelling) grain count distributions appear to be incompatible, generally a result of unavoidably insufficient counting in routine work. A computer program applying the iterative method has been written in Fortran IV for an IBM 1130 machine. This program, available on request, displays grain count distributions before as well as after correction and computes the labelling index and average grain count per labelled cell, with respective variance and standard errors.
STIMULATION OF DNA SYNTHESIS BY ISOPROTERENOL IN RAT SUBMANDIBULAR GLAND DURING POSTNATAL GROWTH
Authors: Barka Tibor , Chang William W. , Van der Noen Hendrika 
Published: May 2008

ABSTRACTThe post‐natal growth of rat submandibular gland and the effect of isoproterenol on this process were studied. Between 2 and 42 days of age the DNA content of the gland increased linearly but the increase in RNA and protein content was more rapid after 29 days of age. The RNA: DNA and protein: DNA ratio increased linearly with age. The proliferative activity, measured by the incorporation of tritiated thymidine, was maximum in the gland of 7‐day‐old rats. It declined steadily to a low level in 42‐day‐old rats. A single injection of isoproterenol had no effect on thymidine incorporation in 2‐day‐old rats. The drug, however, stimulated DNA synthesis in older animals and the degree of stimulation was inversely correlated with the proliferative activity in control rats. Small doses of isoproterenol given to rats for 4 days between 2 and 5 days of age produced a hypertrophy of the submandibular gland. The same treatment between 7 and 10 days of age caused both hypertrophy and hyperplasia of the gland. It is concluded that both the regulation of growth and the regulation of induced cell proliferation are a function of cellular differentiation and that cell proliferation can be induced only in cells that reached a certain degree of differentiation.