bluuebunny/crossref_metadata_2025_split huggingface dataset:
CELL CYCLE CHARACTERISTICS OF SYNCHRONIZED AND ASYNCHRONOUS POPULATIONS OF HUMAN CELLS AND EFFECT OF COOLING OF SELECTED MITOTIC CELLS
Authors: Pettersen E. O. , Bakke O. , Lindmo T. , Oftebro R. 
Published: May 2008

ABSTRACTThe method of synchronizing cells by means of mitotic selection has been adapted to the human line NHIK 3025. Increase in cell number as a function of time in asynchronous and synchronous populations was studied as well as mitotic index as a function of time after selection of synchronized populations. Phase durations of the cell cycle of synchronous populations were determined by 3 H‐thymidine incorporation and scintillation counting. The relative phase durations of exponentially growing asynchronous populations were determined by mathematical analysis of DNA‐histograms recorded by flow cytofluorimetry. Both the generation time and the various phase durations of the cell cycle were found to be the same in asynchronous and synchronous populations. It was found that NHIK 3025 cells are damaged by cooling to 4 and 0°C so that cooling of selected cells in order to increase the yield would reduce the quality of the synchronized populations.
CIRCADIAN RHYTHMS OF PRESUMPTIVE STEM CELLS IN THREE DIFFERENT EPITHELIA OF THE MOUSE
Authors: Potten Christopher S. , Al‐Barwari Shlemon E. , Hume William J. , Searle Jeffrey 
Published: May 2008

ABSTRACTVariation in the percentage of labelled cells (LI), mitoses (MI) and apoptosis (AI: i.e. shrinkage necrosis) have been studied throughout a 24 hr period (40 min after labelling with 3H‐TdR) for tongue epithelium, epidermis and intestinal epithelium in the mouse. A room with reversed light cycle was used to obtain data for half of the 24 hr period. All three tissues showed marked variations in LI with peak values between 24.00 and 03.00 hours. In the intestine a maximum value for MI was observed 3‐6 hr after that for LI and with a maximum value for AI slightly later.In all three epithelia the circadian rhythm was most striking in cells at positions which can be correlated with presumptive stem cell activity; e.g. in the crypts the labelling and mitotic peaks reflecting a circadian rhythm were most clearly distinguishable at the basal part of the crypts. These observations are discussed in relation to the validity of various proliferative models.
AN EXTENDED TRANSITION PROBABILITY MODEL OF THE VARIABILITY OF CELL GENERATION TIMES
Authors: Svetina S. 
Published: May 2008

ABSTRACTThe transition probability model of variability of cell generation times is extended so that the rate constant for the transition from the A‐state to the B‐phase of the cell cycle depends on time which a particular cell has already spent in the A‐state. A specific time dependence of this rate constant is introduced. It is determined by the value of one constant which is then an additional parameter of the model. The corresponding cell population kinetics are calculated and compared to existing experimental evidence. The model accounts satisfactorily for the generation time distribution function and for the shortening of the G1 phase of binucleate cells. The time dependence of the transition probability is related to the cell kinetics of an hypothetical cell constituent. A possible relationship is proposed between the chemical parameters within the cell and the parameters of the cell population kinetics.
SERIAL TRANSPLANTATION, HISTOLOGY AND CELLULAR KINETICS OF A RAT ADENOCARCINOMA
Authors: Moore J. V. , Dixon B. 
Published: May 2008

ABSTRACTData are reported on the growth, histology and cell population kinetics of a spontaneous mammary tumour in the rat at the 1st and 35‐40th transplantation generation. With serial transplantation subcutaneously in isologous animals, the macroscopic growth characteristics of the tumour did not alter. The tumour had a volume doubling time of approximately 1.6 days at 400 mm3, increasing to about 7 days at 20,000 mm3.The histology, however, changed dramatically from that of a well differentiated papillary adenocarcinoma with a well defined vascular pattern and minimal necrosis to become by the 35th generation a poorly differentiated pleomorphic cellular tumour in which stromal elements and associated vascular supply were minimal and necrosis prominent. These changes were not manifested in the median cycle time of its cells, 16–18 hr, but by an increase in the growth fraction from 0.36 to 0.59 with a commensurate increase in the cell loss factor from 0.04 to 0.30.
AN IN VIVO STATHMOKINETIC STUDY OF CELL PROLIFERATION IN HUMAN GASTRIC CARCINOMA AND GASTRIC MUCOSA
Authors: Wright Nicholas A , Britton David C. , Bone George , Appleton David R. 
Published: May 2008

ABSTRACTCell production rates were studied in a group of eleven patients with carcinoma of the stomach using an in vivo technique with vincristine. In normal pyloric mucosa estimates ranged from 8 to 15 cells/1000 cells/hr, and in the carcinomas from 3 to 24 cells/1000 cells/hr. Because of the very large variation in the data, comparison between individual tumours and normal mucosa is not regarded as being worth while at this stage. The implications of these results for previous human in vivo stathmokinetic experiments are also discussed.
REGULATION OF MATURATION RATE OF MOUSE GRANULOCYTES
Authors: Bbenestad Haakon , Rytömaa Tapio 
Published: May 2008

ABSTRACTRegenerating mouse bone marrow cells were cultured i.p. in diffusion chambers (DC) to study factors affecting the maturation rate of granulocyte precursors. One day after exposing 3‐day‐old DC cultures to 3H‐thymidine the cultures were harvested, and labelled proliferative and non‐proliferative granulocytes were counted in radioautographs. The relative maturation rate—defined as the fraction of proliferative precursors maturing into the non‐proliferative compartment per unit time—could be increased by different experimental procedures that inhibit cell production. Inhibition was obtained (a) by increasing culture cellularity; (b) by implanting DC into normal rats or rats with huge s.c. chloroma tumours rather than into mice; and (c) by treating the cells with leucocyte extracts (granulocyte chalone) during the last day of culture. Furthermore, a sudden inhibition of rapidly proliferating granulocytes by leucocyte extracts resulted in an increase (apparently transient) in the absolute number of labelled non‐proliferative granulocytes. Such an increase was not detected in experiments involving a stronger or sustained inhibition of granulopoiesis, evidently because the size of the precursor population had been markedly reduced.
COMPARISON OF GROWTH CHARACTERISTICS OF EXPERIMENTAL TUMOURS AND DERIVED CELL CULTURES
Authors: Barendsen G. W. , Janse H. C. , Deys B. F. , Hollander C. F. 
Published: May 2008

ABSTRACTCells from seven different rat tumours and a mouse sarcoma have been transplanted in syngeneic animals and were cultured in vitro. Tumours produced by inoculation of cultured cells in animals have been compared with the primary tumours. For the transplanted tumours, volume doubling times, Td, have been compared with doubling times, Td(cult), of cell numbers in cultures. Volume doubling times of the transplanted tumours generally decrease with increasing volume. At volumes of about 0.5 cm3, Td values range from 2.2 days to 10 days, while Td(cult) values ranged from 11 to 24 hr. A systematic correlation between Td and Td(cult) could not be established. During sequential transplantation of the tumours for many generations, as well as during continuous propagation of derived cell cultures, significant changes occurred which resulted in a decrease in the expression of differentiation characteristics in tumours.
REPLICON NUMBER AND GROWTH RATE IN FATHEAD MINNOW CELLS CULTURED AT 14 AND 34°C
Authors: Grabar F. , Flickinger R. A. 
Published: May 2008

ABSTRACTDNA fiber autoradiography was performed on cells of the fathead minnow cultured at 14 and 34°C. Replicon growth rates were found to be about twice as fast at the higher temperature, but there was no appreciable difference in the number of replicons.
The Circadian Variations In the Eithelial Growth of the Hamster Cheek Pouch: Quantitative Analysis of Dna Distributions*
Authors: Møller U. , Larsen J. K. 
Published: May 2008

ABSTRACTThe pronounced diurnal rhythm in DNA distribution of the hamster check pouch epithelium both in the S fraction and in the (G2+ M) fraction was compared with previous studies of the changes in tritiated thymidine labelling index and mitotic activity. the DNA distributions were obtained by flow cytometry after ultrasonic disaggregation of the isolated epithelium into a suspension of single nuclei. the DNA distributions were analysed with the computer program of J. Fried (1976) and by planimetry. the S fraction was higher than the autoradiographic labelling index during the whole 24 hr period. Only the computer fitted S fraction and the labelling index had the same difference between maximal and minimal values, and maxima at the same time of day. the DNA distributions showed a diurnal release of G1 cells into S phase proceeding through (G2+ M) phase and returning to G1 phase within a 24 hr period.
Cell Proliferation and Ageing In Mouse Colon
Authors: Hamilton Elizabeth 
Published: May 2008

ABSTRACTThe descending colon of 4 month and 2 year old mice was exposed to 1250 rad X‐rays. This killed most of the epithelial cells. the surviving cells formed new crypts and surface epithelium in animals of both ages. Not all the crypts were replaced. the irradiated area contained no more than 80% of the control number of crypts per section for at least 6 weeks after irradiation. In the young mice new crypts were much larger and the labelling index (LI) was much higher than in unirradiated animals during the first week after irradiation. In the old mice the overshoot in LI and crypt size began later and continued longer than in young animals. This may be because the control of cell proliferation was much less precise in old than in young mice.The irradiation was repeated, in an attempt to age prematurely the epithelial cells by increasing the number of divisions they underwent. the overshoot in LI and cells per crypt was smaller after a second dose than after the first in both young and old mice. There was almost no overshoot after a third dose was given to young mice.Increasing the number of divisions undergone by the surviving epithelial cells did not change the timing of repopulation in young mice compared to that found in old mice. Little evidence was found for the presence of a limited proliferative lifespan in colon epithelial cells.
SPECIFICITY of EPIDERMAL CHALONE EXTRACTS FOR HUMAN EPIDERMOID TUMOUR CELLS IN VITRO: A PRELIMINARY REPORT
Authors: KORSGAARD R. , IVERSEN O. H. , ISAKSSON‐FORSÉN G. , BURTON D. R. 
Published: May 2008

ABSTRACTIn order to test the mitosis‐inhibiting effect and the tissue specificity of the epidermal G2 chalone for tumour cells, extracts from hairless mouse epidermis were tested in short‐term tissue cultures of cells from human respiratory tract epidermoid carcinomas and adenocarcinomas. the chalone inhibited strongly the mitotic activity in two cases of histologically proven epidermoid carcinoma, and had no effect in two cases of adenocarcinoma. In one case of a supposed epidermoid carcinoma, the chalone had no effect. Revision of the histology, and the result of autopsy 11 months later, showed that in this case the lesion in the lung had been a poorly differentiated metastasis from an adenocarcinoma of the ovary. Liver extracts produced in the same way as the epidermal extracts showed no mitotic inhibition in any of the cultures. These results indicate that epidermal G2 chalone produced from mouse skin is tissue specific for human epidermoid tumour cells, and also indicate that a chalone test might be used as a diagnostic tool for poorly differentiated carcinomas to see whether they are of epidermoid origin or not.
The Proliferative State of Clonogenic Cells In the Lewis Lung Tumour After Treatment With Cytotoxic Agents
Authors: Bateman A. E. , Steel G. G. 
Published: May 2008

ABSTRACTThe proportion of clonogenic cells from the Lewis lung carcinoma which are in S‐phase of the cell cycle has been measured as the fraction killed by a short exposure to hydroxyurea in vitro. Estimates of the proportions of Sphase cells before and 30 min after doses of γ‐radiation of 1000–2000 rad suggest no alternation in the cell cycle age distribution due to these doses of radiation. As the survivors of these high doses of radiation are predominantly hypoxic, the results imply that hypoxic cells have the same cell cycle age distribution as oxygenated cells in Lewis lung tumours. After treatment with cyclophosphamide or CCNU, the proportion of S‐phase cells among the survivors exceeds the faction of S‐phase cells in untreated populations. This increase is consistent with a relative resistance of S‐phase cells to alkylating agents and nitrosoureas.
Cell Kinetics and the Control of Growth In Long Bones
Authors: Kember N. F. 
Published: May 2008

ABSTRACTThe cell kinetics of the cartilage growth plate are outlined and discussed in terms of the probable levels of control on the system. Possible mechanisms of growth control at the cellular level are examined for (i) the rate of cell division in the proliferation zone, (ii) the command to differentiate that limits the size of the proliferation zone and (iii) the ageing process in the cartilage plate. the evidence of cell kinetics does not point unequivocally to any particular mechanism.
Erythrokinetics In Mice Bearing Tumours In Either Preirradiated Or Unirradiated Tissue
Authors: JIRTLE R. L. , CLIFTON K. H. 
Published: May 2008

ABSTRACTExperiments were designed to clarify the causes of anaemia in hosts bearing tumours in either unirradiated or preirradiated tissue. Isotopic methods are described which enable the estimation of erythrocyte destruction and production rates, and the potential red cell life spans in tumour‐bearing animals. In this experimental system, anaemia (a) is in large part due to accelerated random erythrocyte loss, (b) is exacerbated as tumours grow by a progressive reduction in the potential erythrocyte life span due to intrinsic erythrocyte defects, (c) is accompanied by an increase in erythrocyte production of six‐ to ten‐fold and (d) is postponed in onset and decreased in magnitude by preirradiation of the tumour transplant site.
The Measurement of Cell Turnover Rates Using Stable Isotope‐Labelled Thymidine: Experiments On the Small Intestine and On A Transplantable Lymphatic Tumour of the Mouse
Authors: Heck H. d'A. , Dyer R. L. , Anbar M. , Becker F. A. 
Published: May 2008

ABSTRACTMultilabelled, non‐radioactive thymidine and tritiated thymidine were incorporated simultaneously into the DNA of a rapidly‐growing, transplantable mouse lymphoma and the DNA of mouse small intestine by a single intraperitoneal injection of both labelled nucleosides. Mice were killed at selected times during the next 7 days, and the specific activities of the tissues and extracted DNA and the 132/126 mass ratio of thymine isolated from the DNA were determined by scintillation counting and by field ionization mass spectrometry respectively. the rates of decrease of the concentrations of tritiated and stable isotope‐labelled thymine in the DNA of the tumour or of the intestine were essentially identical. These results indicate the feasibility of using thymidine multilabelled with stable isotopes for measurement of cell turnover rates in conjunction with cancer therapy.
Changes In Cell Population Kinetics During Epidermal Carcinogenesis
Authors: Fukuda M. , Okamura K. , Rohrbach R. , Bohm N. , Fujita S. 
Published: May 2008

ABSTRACTThe changes in cell population kinetics in response to a mechanical stimulation by wounding were studied in a hyperplastic epidermis, papilloma and a squamous cell carcinoma of the mouse dorsal skin induced by repeated treatments with 20‐methylcholanthrene.The Go cell population, which consists of about 66% of the basal cells in the dorsal epidermis of the normal mouse, disappeared in hyperplastic epidermis, papilloma and carcinoma. the zone of proliferating cells enlarged in the papilloma, including several supra‐basal layers, in contrast to its strict localization in the basal layer in hyperplastic epidermis. Proliferating cells were distributed in almost all areas in the carcinoma without localization. the normal responses to wounding were preserved in the hyperplastic epidermis, except for the absence of Go cells, while the papilloma and carcinoma showed no increase in proliferating cells or shortening of the cell cycle time. From the view‐point of cell population kinetics, papilloma and carcinoma are regarded as the tissues in which the flexible control mechanisms of irreversible cell differentiation to mature cells and of the length of cell cycle time are lacking.
Cell Cycle And The Concept Of Physiological Age With Special Reference To Pyruvate Kinase Activity In Wi‐38 Cells
Authors: Steward P. G. , Kapp L. N. , Klevecz R. R. 
Published: May 2008

ABSTRACTWi‐38 Cells Were Synchronized By Mitotic Collection And Periodically Assayed For Pyruvate Kinase Activity. The Kinetics Of The Synchronous Cohort Were Determined By Continuous Labelling Index And By Mitotic Index. The Experimental Data Were Analysed By Computer Using A State Vector Model To Yield The Probability Density Functions For Phase Transit Times And For Cell Physiological Ages. Pyruvate Kinase Activity For These Cells As A Function Of Physiological Age Was Then Examined Using The Computer Model. Considering Dna Synthesis, Pyruvate Kinase Activity And Mitosis To Be Markers Of Physiological Age, It Was Found That A Model Which Assumes That A Cohort Of Synchronized Cells Desynchronizes Irreversibly And Uniformly From One Age Marker To The Next Is Incompatible With The Experimental Data. For Example, The Times Over Which Cells Entered The S Phase Were Too Widely Distributed To Be Consistent With The Mitotic Index Data. Also, For Pyruvate Kinase Activity To Be A Function Of Physiological Age Alone, The Cell Ages Were Probably Too Dispersed To Be Compatible With The Experimental Enzyme Data. Alternative Models For Cell Physiological Ageing Are Presented, Which Are Compatible With The Experimental Data.
Kinetic Models of C3h Mouse Mammary Tumor Growth: Implications Regarding Tumor Cell Loss
Authors: Roti J. L. Roti , Bohling V. , Dethlefsen L. A. 
Published: May 2008

ABSTRACTThree models of tumor cell loss are described. the effects of cell loss on other cellular kinetic parameters are evaluated, and experiments which may distinguish among the models are discussed. Each model is based on a different cell‐loss mechanism, and equations for the cell‐cycle, cell‐frequency distribution, the growth of both the proliferating and non‐proliferating cell population, the growth fraction (GF), and the relative rate of volumetric growth, (dV/dt)/V, are derived.The following types of data are simulated for each model: the pulse labelling index, the mitotic index, and the labeling index as a function of time after a single or a series of 3H‐TdR injections. the relative volumetric growth rate has the same mathematical form for each model. the PLM curves predicted by each model for the tumor lines studied (S102F and Slow) are not appreciably different. the predicted initial labeling index and mitotic index may differ significantly among the models depending upon the tumor line. the most striking difference among the models lies in the predictions regarding the labeling index as a function of time after a single or after a series of 3H‐TdR injections. These types of labeling experiments should be valuable for distinguishing the different cell‐loss mechanisms in solid tumors.
Species‐Specific Aggregation Factor In Sponges
Authors: Müller W. E. G. , Müller I. , Zahn R. K. , Kurelec B. 
Published: May 2008

ABSTRACTIn dissociated single cells from the sponge Geodia cydonium, DNA synthesis is initiated after incubation with a homologous, soluble aggregation factor. During the DNA‐initiation phase the cyclic AMP‐ and cyclic GMP levels vary drastically; the cyclic AMP content drops from 2.2 pmol/106 cells to 0.3 pmol/106 cells while the cyclic GMP content increases from 0.6 pmol to 3.7 pmol/106 cells. the activity of neither the adenylate cyclase nor of the guanylate cyclase isolated from cells which have been incubated for different periods of time with the aggregation factor, is changed. the soluble as well as the particulate enzyme activities were checked in vitro. the cyclic nucleotide receptors have been isolated from the sponge cells and characterized with respect to their molecular weight, dissociation constant for cyclic AMP or cyclic GMP and intracellular concentration. None of these parameters are altered during aggregation factor‐mediated DNA initiation. From these data it is concluded that the regulation of cyclic nucleotide levels is a consequence of a changed activity of nucleotide cyclases or of phosphodiesterases, but this is presumably not caused by a changed rate of synthesis of nucleotide cyclases or of cyclic nucleotide receptors.
EFFECTS OF HUMAN LEUKOCYTE CONDITIONED MEDIUM ON MOUSE HAEMOPOIETIC PROGENITOR CELLS
Authors: Wagemaker G. , Peters M. Frances 
Published: May 2008

ABSTRACTMedium conditioned by human peripheral blood leukocytes (HLCM) was studied for its in vitro effects on haemopoietic progenitor cells (CFU‐s and CFU‐c) present in mouse bone marrow. HLCM has poor colony stimulating activity in semi‐solid cultures of mouse bone marrow cells. but invariably increases the number of colonies obtained in the presence of plateau levels of semi‐purified colony stimulating factor (CSF). In liquid cultures, HLCM appears to contain a potent initiator of DNA synthesis in CFU‐s. an activity which coincides with an increased CFU‐s maintenance and causes a three‐ to four‐fold increase in CFU‐c number. It is apparent from this study that HLCM, in addition to stimulating colony formation in cultures of human bone marrow cells, has a profound in vitro effect on primitive haemopoietic progenitor cells of the mouse, which cannot be attributed to CSF.
The Proliferative Status And Clonogenic Capacity Of Tumour Cells In A Transplantable Rhabdomyosarcoma Of The Rat Before And After Irradiation With 800 Rad Of X‐Rays
Authors: Hermens A. F. , Barendsen G. W. 
Published: May 2008

ABSTRACTR‐1 Rhabdomyosarcomas Transplantable In The Inbred Strain Of Wag/Rij Rats Were Labelled Semicontinuously With 3H‐Tdr And Subsequently Irradiated With X‐Rays In Order To Estimate The Rate Of Recruitment Of Q Into P Cells And To Obtain More Insight Into The Importance Of Hypoxia With Respect To The P And Q Status Of Clonogenic Cells. Labelling Was Performed By Giving Animals From One To A Total Number Of Up To Seven Intraperitoneal Injections With 3H‐Tdr Within 30 Hr. Half Of The Number Of Tumours Received An Acute Dose Of 800 Rad Of 300 Kv X‐Rays At 45 Min After Completion Of The Last Labelling In Order To Reduce The Fraction Of Well Oxygenated Cells Among The Surviving Clonogenic Cells To Less Than 1%; Labelled Control Tumours Were Sham Irradiated. Fractions Of Labelled Tumour Cells, LiTumour’Were Evaluated From Autoradiographs Prepared From Sections Of Tumours That Were Fixed 15 Min After Irradiation: Fractions Of Labelled Cell Foci, LiFo, Were Determined In Autoradiographs Prepared From Cultures Of Cells Isolated From The Remaining Parts Of The Tumours.Analysis Of The Variation In LiTumour As A Function Of Time And Of The Number Of Injections Showed That The Rate Of Recruitment Of Q Cells Into P Cells Is Most Likely Less Than 1%/Hr. Comparison Of Data On LiFo Derived For Irradiated And Non‐Irradiated Tumours Indicates That Clonogenic Q Cells Are More Frequently Present Among Cells Which Survived The Dose Of 800 Rad Of X‐Rays. These Results Suggest That, In R‐1 Tumours Of About 800 Mm3 The Clonogenic Q Cell Population Contains A Larger Fraction Of Hypoxic Cells Than The Fraction Of Hypoxic Cells Present In The Clonogenic P Cell Population.Several factors are discussed which complicate the analysis and may influence the results, e.g. reutilization of labelled debris of dead cells from irradiated tumours.