bluuebunny/crossref_metadata_2025_split huggingface dataset:
CELL PROLIFERATION KINETICS OF EPIDERMIS AND SEBACEOUS GLANDS IN RELATION TO CHALONE ACTION
Authors: Laurence Edna B. , Spargo D. J. , Thornley A. L. 
Published: May 2008

ABSTRACTMedian S‐phase lengths of pinna epidermis and sebaceous glands, and of epithelia from the oesophagus and under surface of the tongue of Albino Swiss S mice were estimated by the percentage labelled mitoses method (PLM). The 18.4 and 18.8 hr for the median length of S‐phase for pinna epidermis and sebaceous glands respectively made it possible for these two tissues to be used experimentally for testing tissue specificity in chalone assay experiments. The 10.0 and 11.5 hr for oesophagus and tongue epithelium respectively made experimental design for chalone assay difficult when pinna epidermis was the target tissue.The results of the Labelling Index measured each hour throughout a 24‐hr period showed no distinct single peaked diurnal rhythm for pinna epidermis and sebaceous glands. Instead a circadian rhythm with several small peaks occurred which would be expected if an S‐phase of approximately 18 hr was imposed on the diurnal rhythm. This indicates that there may be very little change in the rate of DNA synthesis.The results are given for the assay in vivo of purified epidermal G1 and G2 chalones, and the 72–81% ethanol precipitate of pig skin from which they could be isolated. These experiments were performed over a time period which took into account the diurnal rhythm of activity of the mice as well as the S‐phase lengths. Extrapolating the results with time of action of the chalone shows that the G1 chalone acts at the point of entry into DNA synthesis and that the S‐phase length was approximately 17 hr for both the pinna epidermis and sebaceous glands. This may be a more correct value since the PLM method overestimates the median S‐phase length as it is known that in pinna skin the [3H]TdR is available to the tissues for 2 hr and true flash labelling does not take place. The previous reports that epidermal G1 chalone acts some hours prior to entry into S‐phase resulted from experiments on back skin where the S‐phase is shorter and there is a pronounceddiurnal rhythm which could mask the chalone effect. The epidermal G, chalone had no effect on DNA synthesis even at different times in the circadian rhythm.Thus the circadian rhythms and S‐phase lengths of the test tissues need to be considered when experiments are performed with chalones. Ideally, the target tissues selected for cell line specificity tests should have the same cell kinetics for the easier and more accurate assessment and interpretation of results. When the tissues have markedly different cell kinetics, experimental procedures and results need to be evaluated accordingly. The point of action of G, chalone can only be assessed if the effect is measured over the peak of incorporation of 13H]TdR into DNA.The results of the effects of skin extracts are analysed in relation to changes in the availability of i3H]TdR for the incorporation into DNA and to the possibility of there being two distinct populations of proliferating cells.
ANALYSIS OF INTESTINAL CELL PROLIFERATION AFTER GUANETHIDINE‐INDUCED SYMPATHECTOMY
Authors: Klein R. M. 
Published: May 2008

ABSTRACTNeonatal administration of guanethidine‐sulfate results in an alteration of the cell proliferative pattern of the small intestinal epithelium of the young adult rat. Sympathectomy with guanethidine has previously been shown to depress mitotic, labelling, and total cellular migration indices while increasing the generation cycle time (TC) of small intestinal crypt cells as measured by a stathmokinetic method. The present study showed that the G1, S and G2 phases of the crypt cell cycle are altered by sympathectomy, G1 accounting for most of the increase in TC. In addition, the percentage of [3H]‐thymidine labelled crypt cells is reduced and the duration of crypt cell transit is lengthened by guanethidine‐induced sympathectomy.
CELL‐PRODUCTION RATES ESTIMATED BY THE USE OF VINCRISTINE SULPHATE AND FLOW CYTOMETRY
Authors: Barfod I. H. , Barfod N. M. 
Published: May 2008

ABSTRACTA new method for the evaluation of cell production rates combining flow cytometry (FCM) and the stathmokinetic method using vineristine sulphate (VS) has been used for the analysis of three aneuploid ascites tumours at different stages of growth. Using this technique it was possible to estimate the well‐known decrease in cell production rates of ageing ascites tumours. The percentage of normal host cells in the aneuploid tumours studied was easily determined by FCM prior to the calculation of the tumour cell‐production rates. A correlation was found between the percentage of tumour cells in the S phase and the tumour cell‐production rate. This correlation is probably explained by the gradual transfer of proliferating cells in S phase to resting G1 and G2 phases with increasing tumour age.
KINETICS OF HUMAN LYMPHOCYTE RESPONSES IN VITRO: THE PHASE OF EXPONENTIAL GROWTH
Authors: Hanrahan L. R. , O'Leary J. J. , Mehta C. , Rosenberg A. 
Published: May 2008

ABSTRACTThe kinetics of thymidine uptake in human peripheral lymphocytes stimulated by allogenic cells, antigen E (ragweed allergen) and a variety of mitogens can generally be divided into four consecutive phases. First, a lag period with no increase in thymidine uptake, then a short period of rapid change in uptake, followed by a log‐linear growth period and finally a decay phase. In this report we examine in detail the characteristics of the third, log‐linear growth phase. Since, as discussed in the preceding paper, thymidine uptake is proportional to the number of cells acumulating thymidine, we can calculate from the log‐linear growth period an apparent doubling time. We show that for five different stimulating agents the cells reach a log‐linear growth phase of varying length and that the doubling times show little variation. This invariance indicates that, despite possible variation in cell death and recruitment rates, the rate of proliferation is in all cases dominated by the generation time of human lymphocytes.
DYNAMIC HISTOLOGY OF A RAT HEPATOMA AND THE RESPONSE TO 5‐FLUOROURACIL*
Authors: Moore J. V. , Hopkins H. A. , Looney W. B. 
Published: May 2008

ABSTRACTThe cellular response of the rat hepatoma 3924A to a single intraperitoneal injection of 5‐fluorouracil has been measured in respect of the spatial relationship of the cells to the tumour microvasculature. In this tumour the parenchyma is arranged in cords approximately 150 μm thick around central capillaries. For untreated tumours, those cells at distances less than 80 μm from the capillary had a mean [3H]TdR labelling index of 39% and a mitotic index of 2·1%, while for those cells more than 80 μm away the values were 14% and 0·8% respectively. Two days after 150 mg/kg of 5‐fluorouracil, mean cord thickness was reduced by 25% and did not recover to the control level until 11 days after treatment. This was also true for the mitotic index. Recovery of the labelling index was complete 2 days earlier. Although absolute values of parameters were different in the populations adjacent to and remote from the capillary, the time course of recovery was similar, with a ‘growth spurt’ 7 to 9 days after treatment. The results from this histologically‐based assay have been compared with those from biochemical/biophysical assays that sample the overall tumour population.
PROLIFERATION STUDIES OF THE ENDOTHELIAL AND SMOOTH MUSCLE CELLS OF THE MOUSE MESENTERY AFTER IRRADIATION
Authors: Hirst D. G. , Denekamp Juliana , Hobson B. 
Published: May 2008

ABSTRACTA continuous labelling technique was employed to study the effects of external β‐radiation on the proliferation of endothelial cells and smooth muscle cells in the mesenteric arterioles of mice. Labelled and non‐labelled cells of either type were determined by autoradiographic techniques in control animals and at different times (3, 12 and 48 weeks) after single doses of 20 and 45 Gy (2000 and 4500 rads). The fraction of cells labelled, even after 7 days of repeated injections was very low in all instances.Calculations showed very long turnover times for the two cell populations in control animals (>2 years for endothelium and >3 years for smooth muscle). After 20 and 45 Gy, no significant increase in endothelial proliferation was seen except at 3 weeks. No significant increase in labelling was observed in smooth muscle at any time after irradiation.These labelling data have been compared with the pattern of cell depletion of the irradiated endothelium. It was concluded that the depletion was much earlier than expected for a slowly proliferating tissue, if all the cells were cycling very slowly. Such an early depletion is, however, consistent with cell death resulting from a small proportion of the cells having a short cell cycle. The recovery of the endothelial cell numbers between 9 and 12 months was not accompanied by a rise in the fraction of labelled cells. It is suggested that repopulation may occur from outside the treated area.
ANALYSIS OF INTESTINAL CELL PROLIFERATION AFTER GUANETHIDINE‐INDUCED SYMPATHECTOMY
Authors: Klein R. M. 
Published: May 2008

ABSTRACTRats were treated with guanethidine‐sulphate every 48 hr from birth until 15 days and then maintained until young adulthood. Sympathectomy was verified by dissection and light microscopic preparation of the superior cervical and coeliac ganglia which showed at least a 78% reduction in the number of perikarya. The effect of the chemical sympathectomy was a decrease in the amplitude of the circadian mitotic rhythm from 44·7 to 27·1%, 67·0 to 25·3% and 54·9 to 24·7%, in the duodenum, jejunum, and ileum, respectively. The shape of the mitotic index curve was altered and the mean mitotic index was significantly decreased (P < 0·01) in all three segments of the small intestine. The mean mitotic index of control intestinal epithelium was 3·2 ± 0·1%, 3·6 ± 0·1% and 4·0 ± 0·1% in the duodenum, jejunum, and ileum, respectively, and 2·3 ± 0·1%, 2·4 ± 0·1%, and 2·5 ± 0·1% in guanethidine‐treated rats. Stathmokinetic estimates of cycle time were obtained by use of the metaphase arrest agent, colchicine. The longest cell generation cycle time (Tc) and lowest mitotic index occurred between 12.00 and 16.00 hours and the shortest Tc and highest mitotic index occurred between 00.00 and 04.00 hours, in all three segments of the small intestine. Guanethidine‐treatment lengthens Tc throughout the small intestinal epithelium and reduces the range of variation in Tc over a 24‐hr period. It is suggested that norepinephrine depletion induced by guanethidine may be the cause of the inhibition in circadian periodicity and that norepinephrine and the sympathetic nervous system may be essential for the maintenance of circadian rhythms in mitotic activity.
COMPARISON OF DNA RENEWAL IN GERM‐FREE AND CONVENTIONAL MICE USING [125I]IODODEOXYURIDINE AND [3H]THYMIDINE
Authors: Webb P. , Chanana A. D. , Cronkite E. P. , Laissue J. A. , Joel D. D. 
Published: May 2008

ABSTRACTGerm‐free (GF) and conventional (CV) C3H mice received a single injection of 1 μCi [3H]thymidine and 3 μCi [125I]iododeoxyuridine to provide simultaneous labeling of DNA with the two precursors. Thymus, spleen, mesenteric lymph nodes, bone marrow (femora), small intestine, colon and skin were examined for total organ activity and rate of DNA renewal 1–8 days after injection. Precursor incorporation, assayed on day 1, was lower in the thymus, mesenteric lymph nodes and femora (and, to a lesser extent, in the spleen and colon) of GF mice as compared to CV animals. The opposite was observed in the small intestine and skin, i.e. total organ activity was higher in GF animals. Differences in precursor incorporation were partly due to differences in organ weights between the two groups of mice.In comparison to CV animals, DNA renewal rates were diminished in the mesenteric lymph nodes, bone marrow, colon (following a 3‐day plateau) and spleen of GF mice. Little, if any, difference was observed between the two groups with respect to the rate of DNA turnover in the thymus and skin. Radioactivity of the small intestine remained constant for 2 days. Thereafter intestinal activity in GF mice declined at an initial slow rate between days 2 and 5 followed by a rapid decrease between days 5 and 8. In CV mice the first phase of activity loss was short with the rapid decline in intestinal activity beginning on day 3.From the slopes of the regression lines, the percentage thymidine reutilization was estimated. Reutilization varied from 0 to 63% in the various organs examined, with the greatest difference between GF and CV mice occurring in the mesenteric lymph nodes.
VARIABILITY OF SHORT‐TERM CULTURES OF HeLa S‐3 CELLS: CHANGES IN DNA DISTRIBUTIONS AND RATES OF DNA SYNTHESIS
Authors: Collins J. M. , Berry D. E. , Bagwell C. B. 
Published: May 2008

ABSTRACTDNA distributions of HeLa S‐3 cells in spinner culture exhibit significant time—dependent changes. The major differences appear to occur in the S‐phase region. Significant changes in the rates of DNA synthesis in several S‐phase subcompartments correlated well with the changes in the DNA distributions. It is proposed that fluctuations in these rates of DNA synthesis are a reflection of the inherent instability of these abnormal, heteroploid cells.
THE EFFECT OF PARTIAL BODY IRRADIATION ON HAEMOPOIETIC STEM CELL MIGRATION
Authors: Croizat H. , Frindel E. , Tubiana M. 
Published: May 2008

ABSTRACTData obtained after various types of partial body irradiation support the concept of a small rapidly exchangeable pool of CFUs, which seems to be exhausted rapidly after irradiation. The depletion of this pool is the most plausible explanation for the decrease in stem cell migration observed 3 hr after exposure in C3H mice. After partial body irradiation the size of the rapidly mobilizable pool is reduced in proportion to the areas of bone marrow irradiated. When only one marrow area is shielded, the recovery of this pool does not occur during the first 24 hr after exposure.
DETERMINING THE LABELING INDEX IN AUTORADIOGRAPHY
Authors: Schoenfeld D. , Kallman R. F. 
Published: May 2008

ABSTRACTA method is proposed for estimating the labeling index in autoradiographs. It is based on a model for the frequency distribution of grain counts for those cells which have few grains. The method does not require extensive grain counting and provides reasonable estimates even when the background level is high. It is particularly suited for experiments where tumor cells, labeled in vivo, are, autoradiographed after being cultured in vitro.
PERITONEAL EXUDATE MONONUCLEAR PHAGOCYTE COLONY‐FORMING CELLS: THEIR PROLIFERATIVE STATE IN VIVO AND SENSITIVITY TO CYTOTOXIC AGENTS
Authors: Lin H.‐S. 
Published: May 2008

ABSTRACTWe investigated the proliferative state of peritoneal exudate macrophage colony‐forming cells (PE‐CFC) by exposing them to [3H]thymidine with a high specific activity in vitro and by administering cytosine arabinoside and methotrexate in vivo. Since [3H]TdR had no appreciable killing effect on PE‐CFC and since the drug treatment caused no reduction in the appearance of PE‐CFC, we concluded that the majority of PE‐CFC, if not all, are not in active cell cycle. The production of PE‐CFC was, however, suppressed by the administration of nitrogen mustard, cyclophosphamide, BCNU and vinblastine.
CYTOKINETIC CHANGES IN THE THYMUS OF TUMOUR‐BEARING AND OF DEXAMETHASONE‐TREATED MICE
Authors: Aherne W. A. , Zaitoun A. M. , Lauder I. , Hull D. L. 
Published: May 2008

ABSTRACTChanges in the cell population kinetics of the Balb/c mouse thymus were studied (a) during the growth of a syngeneic transplantable sarcoma and (b) following intraperitoneal injection of dexamethasone. The weight of the thymus fell briefly after tumour transplantation, then recovered with overshoot and eventually declined profoundly. After dexamethasone injection the weight of the thymus fell to roughly one‐third of its normal value in 36 hr. Similar cytokinetic changes were observed in both sets of experiments; thymic wasting was accompanied by a small increase in thymocyte cell cycle time, a prolongation of the S‐phase of the cycle, a marked decrease in the thymocyte cell production rate and a marked reduction in the growth fraction of the thymocyte population in the superficial Cortex. It is suggested that thymic atrophy in tumour bearing animals may be a stress phenomenon.
ERYTHROPOIETIN‐INDEPENDENT REGENERATION OF ERYTHROID PROGENITOR CELLS FOLLOWING MULTIPLE INJECTIONS OF HYDROXYUREA
Authors: Wagemaker G. , Visser T. P. 
Published: May 2008

ABSTRACTIt was shown previously that colony formation in vitro by early erythroid progenitor cells (BFUe) requires sequential stimulation with a specific glycoprotein termed BFA and erythropoietin (EP). The action exerted by BFA was characterized as induction of proliferation in BFUe resulting after several cell divisions in EP‐responsive progeny. The present study is directed at detection of EP‐independent regulation of erythroid progenitor cells in vivo.Haemopoietic regeneration was induced by multiple administrations of hydroxyurea (HU). The femoral regeneration patterns of haemopoietic stem cells (CFUs), granulocyte/macrophage progenitor cells (CFUgm) and erythroid progenitor cells (BFUe, day 3 BFUe and CFUe) were studied in hypertransfused mice in comparison to nontransfused controls. The results show that (1) the phase of exponential regeneration of none of the cell populations studied is affected by hypertransfusion; (2) each of these cell populations exhibit a distinct regeneration pattern, indicating that they behave as separate functional entities; and (3) the three erythroid cell populations are suppressed by hypertransfusion in the post‐exponential phase of regeneration in contrast to CFUs and CFUgm.The results support a two‐regulator model of erythropoiesis.
THE METAPHASE ARREST TECHNIQUE
Authors: Wright N. A. , Appleton D. R. 
Published: May 2008

ABSTRACTThe accuracy and precision of the stathmokinetic experiment for the determination of cell birth rate are discussed from practical and theoretical viewpoints. Topics covered include the determination of the optimal dosage of the metaphase arresting agent, the times at which observations should be taken and which cells should be counted, the correct method of estimating cell birth rate and the dependence of any derived estimate of the turnover time on the age distribution of cycling cells. Failure to consider any of these points can lead to considerable inaccuracy. It is further shown that the stathmokinetic method is a rather imprecise one for measuring the turnover time and the duration of mitosis.Data are present comparing the results of using the technique with those obtained from autoradiographic studies.
An In Vitro Model of Hematopoietic Injury In Chronic Hypoplastic Anemia
Authors: Fitchen J. H. , Deregnaucourt Josette , Cline M. J. 
Published: May 2008

ABSTRACTMice treated with high‐dose busulfan develop a ‘latent’ form of bone marrow failure characterized by near‐normal peripheral blood counts and marrow cellularity, but marked reductions in marrow pluripotent stem cells (CFUs) and myeloid progenitor cells (CFUc). Spleen cell suspensions from control and ‘latent’ mice were placed in liquid culture in the presence of colony‐stimulating activity. Cells were harvested at intervals up to 14 days and sub‐cultured in agar to assay for CFUc. Baseline splenic CFUc did not differ significantly between control and ‘latent’ mice. Splenic CFUc from control mice increased 50‐fold and reached a peak at day 10 in liquid culture. In contrast, splenic CFUc from ‘latent’ mice increased only 7‐fold and reached a peak at day 3. Our results indicate that although splenic CFUc are present in normal numbers in ‘latent’ mice, their proliferative capacity is markedly reduced, either as the result of defective CFUc self‐renewal or defective feed‐in from CFUs or both.
Variation In G1 Transit Time Relative to the Cycloheximide and Actinomycin D Drug Restriction Points
Authors: Blair O. C. , Roti J. L. Roti 
Published: May 2008

ABSTRACTThe transit time distribution at various points in the cell cycle of synchronized Chinese hamster ovary cells was determined from the mitotic index, [3H]thymidine labeling index and increase in cell number monitored at regular intervals after mitotic selection. Variation in G1 transit time compared with that for the total cell cycle indicates that variation in cell cycle transit time occurs mainly during G1 phase. the cycloheximide (5.0 μg/ml) and actinomycin D (3.0 μg/ml) restriction points occur 0.2 and 1.7 hr prior to entry into S phase, respectively. the transit time distributions are further characterized by the moments of the distributions. the variance (2nd moment about the mean) of the transit time distribution at the actinomycin D restriction point is similar to the variance of the transit time distribution at the G1/S border, thus variation in cell cycle transit time originates earlier than 1.7 hr prior to entry into S phase (i.e., the first 3/4 of G1). If G1 transit time variability and cell cycle control are related, then the results presented here indicate that the major regulatory events do not occur during late G1 phase.
DIFFERENCES AND SIMILARITIES IN ADJUVANT CHEMOTHERAPY IN MOUSE AND MAN
Authors: van Putten L. M. , Gerritsen A. F. C. 
Published: May 2008

ABSTRACTThe effectiveness of adjuvant chemotherapy is easily demonstrated in many mouse models, whereas in man the response is good but far less spectacular. With the aid of a mathematical model the following variables in which differences may exist between mouse and man were tested:1. Uniformity of tumour load in population2. Cell kinetic factors in drug sensitivity3. Variation of drug sensitivity among tumours4. Drug penetration into tumour5. Tumour antigenicity6. Variation in growth rate among tumoursIt is concluded that factors 1 and 3 are responsible for the difference. Mouse models are more sensitive by selection of an effective drug and an optimal tumour load. Other factors seem not to affect the results.
Changes In the Proliferation Characteristics of A Solid Transplantable Tumour of the Mouse With Time After Transplantation
Authors: de Lacroix W. Féaux , Lennartz K. J. 
Published: May 2008

ABSTRACTThe aim of the present investigation was to study changes in cell proliferation kinetics with time after transplantation in a solid transplantable mammary carcinoma of the C3H mouse. From growth curves and tumour doubling times, three different experimental times were chosen; the exponential phase of growth on the 7th day post‐transplantation, during the phase of retardation on the 21st day after transplantation and in the stationary phase of growth on the 30th day after transplantation. It was found that the cell loss factor contributed primarily to the retardation of volume growth. the lowering of the growth fraction played a minor part in the delay of growth while the duration of cell cycle was not prolonged before the plateau phase of growth on the 30th day after transplantation was reached.