bluuebunny/crossref_metadata_2025_split huggingface dataset:
A COMPARTMENTAL ANALYSIS OF CIRCULATORY LYMPHOCYTES IN THE SPLEEN
Authors: Hammond B. J. 
Published: May 2008

AbstractA tentative model describing the passage of circulatory lymphocytes through the spleen is formulated in accord with known anatomical features. In order to preserve isomorphism between the model and the splenic system, the model is formulated in compartmental form and its design allows alternative routes and modes of lymphocyte transit to be considered. The simultaneous differential equations arising from the model are solved using an analogue computer which also provides the means whereby the performance of the model may be compared with suitable dynamic data drawn from literature. This not only allows the selection of a particular configuration of the model in preference to its alternatives, but also allows the numerical determination of certain unknown parameters. In the case of the rat spleen, best agreement between model and experimental data is obtained when between 10 and 25% of the total lymphocyte flux in the model spleen passes through the marginal zone where the average dwell time of the lymphocytes is about 50 min. The white pulp receives a lymphocyte flux from the marginal zone amounting to about 10% of the total splenic flux and the white pulp lymphocytes are sequestered for a period of 4–6 hr before release to the venous circulation. The red pulp receives 90% of the total splenic flux but the majority of lymphocytes find transit through the red pulp in less than 5 min. The remaining flux of lymphocytes, amounting to 10% of the splenic input, is delayed in transit through the red pulp by 2–3 hr before release to the venous circulation.
THE EFFECT OF ESTRADIOL ON THE CELL KINETICS IN THE UTERINE AND CERVICAL EPITHELIUM OF NEONATAL MICE
Authors: Eide Arne 
Published: May 2008

AbstractThe effect of estradiol‐17β on the length of the various phases of the cell cycle was studied in the neonatal mouse uterine, and cervical epithelium. A double labelling method was used, and in addition labelled mitoses were counted. In the uterus proper, estradiol shortens the length of the total cell cycle, Tc, from 17‐9 hr to 15‐7 hr, and the duration of S phase, Ts, from 6–7 to 5‐1 hr 6 hr after estradiol treatment. 12 hr after estradiol treatment, Tc is shortened to 7‐4 hr and Ts to 4–5 hr. The shortening of Tc at 12 hr is mainly due to an effect on TG1, which is shortened from 8–55 hr in untreated animals to 1–8 hr in estradiol treated animals.The Tc of cervix epithelium cells in untreated animals was found to be 21‐8 hr. After treating the mice for 6 hr with estradiol the Tc was now increased to 47 hr and further to 61 ‐2 hr following 12 hr treatment with the hormone. Ts increases from 8‐3 hr to 15‐2 hr following 6 hr estradiol treatment, and to 15‐4 hr after 12 hr treatment. The effect is most pronounced in TG1, which is lengthened from 10–95 hr in untreated animals to 28‐1 hr and 43 hr, respectively, in animals treated for either 6 or 12 hr with estradiol.
THE EFFECT OF CONTINUOUS IRRADIATION ON CELL PROLIFERATION AND MATURATION IN SMALL INTESTINAL EPITHELIUM
Authors: Rijke R. P. C. , Plaisier H. , Hoogeveen A. T. , Lamerton L. F. , Galjaard H. 
Published: May 2008

AbstractAutoradiographic studies and scintillation counting of crypt material after pulse labelling with 3H‐thymidine showed that during continuous irradiation with 290 rads/day a reduced proliferative activity is present in the crypts of rat small intestine after 1 day of irradiation and of normal activity during the remaining period (5 days) irradiation. After cessation of irradiation an increase in proliferative activity can be observed after 1 day of recovery. From the time (36–48 hr after starting of the irradiation) that the number of villus cells is reduced an expansion of the proliferation zone in the crypt was observed. Both effects last until 1 day of recovery after cessation of irradiation. The process of crypt cell maturation and of villus cell function has also been studied during and after continuous irradiation by micro‐chemical enzyme analyses in isolated crypts and villi. It was found that the expansion of the proliferation zone in the crypt is accompanied by a decrease in activity of only those enzymes (i.e. non‐specific esterases) which normally become active during crypt cell maturation. The activity of enzymes normally present mainly in the functional villus cells remained relatively unaffected by changes in crypt cell kinetics. A hypothesis of different regulation mechanisms of the proliferative activity in the intestinal crypt and a possible explanation of the different behaviour of various enzyme activities as a result of changes in crypt cell proliferation is discussed.
NUCLEAR INCORPORATION OF RADIOACTIVE DNA PRECURSORS AND PROGRESSION OF CELLS THROUGH S
Authors: Hirt A. , Wagner H. P. 
Published: May 2008

AbstractBone marrow blast cells of nine children with untreated acute leukaemia (five lymphoid, three myeloid, one monocytic), myeloid precursor cells of a haema‐tologically normal child and thoracic duct lymph cells of a patient with sclerodermia were pulse‐labelled in vitro with tritiated thymidine and/or tritiated cytidine. Combined radioautographic and cytophotometric techniques were used for the determination of the median nuclear size and the median grain count of labelled cells in different segments of S. It was found that the median grain count reached maximum values in the second or third quarter of S in all cell populations studied, and that the variation, during S, of the median grain count appeared to be independent of the median DNA synthesis times of the cell types investigated. In six cell populations a clear‐cut inverse relation existed between the number and the median grain count of labelled cells in different segments of S. In three populations this relation was less apparent and in two it was not found at all.
THE PREDOMINANT ROLE OF THE SPLEEN IN LYMPHOCYTE RECIRCULATION
Authors: Pabst R. , Trepel F. 
Published: May 2008

AbstractLymphocyte recirculation through the isolated pig spleen was studied by means of a perfusion system which kept the organ alive for a prolonged period of time. By changing the perfusate to a leucocyte‐enriched or cell‐free perfusate and taking serial arterial and venous samples, the numbers of lymphocytes which homed to or were released from the spleen were measured. In all experiments more lymphocytes homed than were released per minute. There was no apparent difference when autologous or allogeneic cells were used. The number of lymphocytes released depended on the number of lymphocytes homed previously.During the phase of constant release up to 3‐3 × 106 lymphocytes were released per gram spleen per minute. From these values it can be extrapolated that up to 270 × 109 lymphocytes recirculate through the isolated pig spleen per day. Based on kinetic data from other species it is estimated that in the entire pig a total number of 300–400 × 109 lymphocytes recirculate per day. Thus, it can be concluded that the spleen is the most important organ for lymphocyte recirculation in the pig.
SERUM LEVELS OF COLONY STIMULATING FACTOR(S) AND THE GROWTH OF BONE MARROW CELLS IN DIFFUSION CHAMBERS
Authors: Beran Miloslav 
Published: May 2008

AbstractFluctuations in the body fluids of long‐ranged humoral substance(s) capable of stimulating the growth of bone marrow granulocytic and macrophage‐like cells in diffusion chamber cultures in vivo, was observed after whole body irradiation of mice. The fluctuation pattern was similar to that of the in vitro colony stimulating factor(s) of the sera of irradiated mice which indicates a relation between in vivo and in vitro active factor(s).
CELL KINETICS METHODS FOR CLINICAL USE: ASSESSMENT OF AUTORADIOGRAPHY AND 125I‐IODO‐DEOXYURIDINE WITH MOUSE EHRLICH TUMOUR
Authors: Jenkinson I. S. , Shuter B. J. , Wright P. N. M. 
Published: May 2008

ABSTRACTSuperficial Ehrlich tumours in mice were used to assess how much information on cell kinetics could be obtained from only the simplest techniques of autoradiography, and in situ monitoring of 125I‐iodo‐deoxyuridine. These techniques were selected as being readily applicable to clinical situations. Intradermal tumours were studied from the earliest stages of rapid growth to large slow growing tumours with necrotic cores, as well as tumours undergoing regression. For comparison, intramuscular tumours were studied with systemic injections of radioactive DNA precursors. It was found that extensive information on cell production and loss rates was obtained from a single injection of tritiated thymidine followed by a single biopsy, or alternatively in vitro labelling of one minute biopsy specimen, and measurements of only the labelling index, together with a knowledge of the tumour's growth characteristics. Following a single localized injection of 125I‐iodo‐deoxyuridine, the loss rate of radioactivity measured in situ for a period of about 1 week provided an index of cell loss rate from the tumours.
MATRIX SIMULATION OF DUODENAL CRYPT CELL KINETICS
Authors: Roti Joseph L. Roti , Dethlefsen Lyle A. 
Published: May 2008

ABSTRACTThe perturbed cellular kinetics of the duodenal crypt following a single injection of hydroxyurea (HU) have been simulated using matrix algebra. Following the direct effects of HU (S‐phase cytotoxicity and a G1/S block) the crypt cell kinetics undergo several alterations. Previously documented alterations include: (1) a temporary partial synchronization of the surviving cells, (2) a shortening of the cell‐cycle transit time, and (3) recruitment of normally non‐proliferating cells into active proliferation. These conclusions have been extended by constructing several different complex but theoretically possible recovery models and the validity of each of these models has been evaluated by simulating the following biological data: the number of cells in the S and M‐phase of the cell cycle, total viable cells per crypt, and the per cent labeled mitosis and the number of labeled cells following 3H‐TdR injections at 9 and 21 hr after HU treatment. The model which showed visually the best overall agreement with all sets of the data was chosen as ‘most probable’ and leads to the following interpretations. Immediately after the end of the HU block (i.e. 5 hr after HU injection) the modal cell‐cycle transit time is reduced to 8 hr. By 17 hr after HU, the modal transit time is increased to 10 hr. Repopulation of the proliferating compartment, i.e. restoration of the proliferating compartment back to the control value, occurs between 12 and 17 hr after HU injection and probably consists of both recycling of the proliferating cells (i.e. they do not progress up into the non‐proliferating compartment) and recruitment of the non‐proliferating cells into active proliferation. Also, the rate at which the non‐proliferating cells move onto the villi is reduced temporarily. The overall recovery process results in a crypt which temporarily is larger than control and produces villi cells at a rate which is faster than the control. The time when the crypt size and villus cell production rate return to normal cannot be established using the available data.
A NON‐DESTRUCTIVE METHOD FOR MEASURING INTESTINAL CELL TRANSIT TIME
Authors: Hagemann Ronald F. , Cooper John , Poulakos Lawrence 
Published: May 2008

ABSTRACTVillous exfoliation of intestinal epithelial cells, which had been previously labeled in the crypt with 125I‐iododeoxy‐uridine, can be detected by thyroidal accumulation of the liberated 125I‐. The latter can be monitored externally. The interval between labeled precursor injection and the steep portion of the thyroid activity accumulation curve corresponds to the intestinal cell transit time, as measured by destructive techniques, in three animal species. The technique allows estimations of intestinal cell transit time to be made on an individual basis, and can be expeditiously applied to large animals. Very small tracer doses are required for detection.
NUCLEOCYTOPLASMIC RATIO REQUIREMENTS FOR THE INITIATION OF DNA REPLICATION AND FISSION IN TETRAHYMENA
Authors: Worthington D. H. , Salamone M. , Nachtwey D. S. 
Published: May 2008

AbstractHydroxyurea (10 mM) arrests the exponential growth of Tetrahymena by blocking DNA replication during S‐phase. After removal of the hydroxyurea (HU), they have a long recovery period during which they are active in DNA synthesis. 3H‐TdR uptake showed that on completion of the recovery period, the cells divide (recovery division) and enter a cell cycle which lacks G1. The frequency, size and DNA content of the extranuclear chromatin bodies (ECB) formed at this division are all markedly increased (2–4) over the corresponding values obtained from exponential growth phase controls. Microspectrophotometric analysis of macronuclear DNA content (N) coupled with the cytoplasmic dry mass (C) values suggest that specific N to C ratios (N/C) are required for the initiation of DNA replication and fission: during a normal (exponential growth) cell cycle, both N and C double, but asynchronously, so that the N/C of both post‐fission‐daughter cells and pre‐fission cells is identical (standardized to N/C = 1) but late G1 cells have a low N/C. During a 10 hr exposure to HU, the N remains essentially the same whereas the C increases. When the HU is removed, the N increases by 4× and the C continues to increase until just prior to recovery division when it also reaches a value 4× that of the original daughter cells. Thus, the N/C = 1 is re‐established. The enlarged ECB formed during recovery division may function to lower the N/C in the daughter cells, which in turn may in some way stimulate immediate DNA replication, thus eliminating G1. The elimination of G1 (and shortening in a few subsequent cell cycles) allows less time for cytoplasmic growth and results in the return of the cells to the generation time and the N and C values observed prior to the HU treatment.
THE CELL PROLIFERATION KINETICS OF THE EMT6/M/AC MOUSE TUMOUR AT FOUR VOLUMES DURING UNPERTURBED GROWTH IN VIVO
Authors: Watson James V. 
Published: May 2008

AbstractThe cell proliferation kinetics of the EMT6/M/AC mouse tumour were determined at four different volumes between 1–5 mm3 and 175 mm3. The decrease in the growth rate between these volumes was mainly due to a decrease in the rate constant for cell production. A small increase in the rate constant for cell loss occurred, but this was thought to be insignificant. The cell loss factor increased from 40% at 1–5 mm3 to over 70% in the 175 mm3 tumours. An increase in the median cell cycle time, from 14‐1 hr to 18‐5 hr was also found between these same volumes. Results obtained for the NCTC fibrosarcoma and the R‐l rhabdomyosarcoma indicate that there may be a threshold volume in these sarcomas below which little or no cell loss takes place. This was not found in the EMT6/ M/AC tumour.
CHARACTERISTICS OF THE ISOPRENALINE STIMULATED PROLIFERATIVE RESPONSE OF RAT SUBMAXILLARY GLAND
Authors: Koschel K. W. , Hodgson G. S. , Radley J. M. 
Published: May 2008

AbstractA simple stochastic model has been developed to determine the cell cycle kinetics of the isoprenaline stimulated proliferative response in rat acinar cells. The response was measured experimentally, using 3H‐TdR labelling of interphase cells and cumulative collections of mitotic cells with vincristine. The rise and fall of the fraction of labelled interphase cells and of metaphase cells is expressed by the product of the proliferative fraction and a difference of probability distributions. The probability statements of the model were formulated and then compared by an iterative fitting procedure to experimental data to obtain estimates of the model parameters. The model when fitted to the combined fraction labelled interphase (FLIW) and fraction metaphase (FMW,) waves gave a mean Gis transit time of 21‐2 hr, mean Gis+ S transit time of 270 hr, and mean Gis+ S + G2 transit time of 35‐8 hr for a single injection of isoprenaline, where Gis is the initiation to S phase time. When successive injections of isoprenaline were given at intervals of 24 and 28 hr the corresponding values after the third injection were 12‐4 hr, 20‐8 hr and 25‐7 hr respectively. The variance of the Gis phase dropped from 18‐1 to 1–3 while the other variances remained unchanged. The estimated proliferative fraction was 0–24 after a single injection of isoprenaline, and 0–31 after three injections of the drug. Independently determined values of the proliferative fraction, obtained from repeated 3H‐TdR injections, were 0–21 and 0–36 respectively.
STUDY ON THE PROLIFERATIVE STATE OF HAEMOPOIETIC STEM CELLS (CFU)
Authors: NEČAS E. , POŇKA P. , NEUWIRT J. 
Published: May 2008

AbstractHydroxyurea was used to study the proliferation rate of haemopoietic stem cells (CFUJ in normal mice, after irradiation or transplantation into irradiated recipients. It was demonstrated that the proliferation rate of endogenous CFUS (endo‐CFU,) and exogenous CFUS (exo‐CFUs) are identical. After irradiation (650 R) the surviving endo‐CFUs begin to proliferate immediately. By contrast exo‐CFU, transplanted into the irradiated recipient mouse (850 R), begin to proliferate only after about 30 hr.However, injection of isoproterenol (which stimulates adenyl cyclase) or dibutyryl cyclic adenosine 3′,5′‐monophosphate shortly after marrow cell graft, triggers the transplanted CFUS into cell cycle as shown by an almost immediately increased sensitivity to hydroxyurea. Isoproterenol is capable of inducing DNA synthesis also in stem cells of normal mice but it takes about 20 hr before CFU, become to be increasingly sensitive to hydroxyurea.
THE MIGRATION OF LYMPHOCYTES ACROSS SPECIALIZED VASCULAR ENDOTHELIUM
Authors: Sedgley M. , Ford W. L. 
Published: May 2008

AbstractThe chain of lymph‐nodes in the rat mesentery was isolated and the preparation was perfused via cannulae in the superior mesenteric vessels. The perfusate consisted of serum to which labelled lymphocytes had usually been added. The entry of radioactively labelled lymphocytes from the blood vessels into the lymph‐nodes was studied by scintillation counting and autoradiography.It was observed that: (1) In the perfused node labelled lymphocytes localized in and around post‐capillary venules in the paracortex as they do early after i.v. injection. (2) The number of lymphocytes which entered the node was directly proportional to the concentration in the perfusate over the range studied. The proportion of cells retained in the node varied considerably around a mean of 11 % of lymphocytes reaching it. (3) The isolated lymph‐node released few if any lymphocytes into the effluent (venous) perfusate. (4) Large lymphocytes migrated into isolated lymph‐nodes slightly more readily than did small lymphocytes. (5) Unlike intact cells isolated lymphocyte membranes did not adhere to specialized vascular endothelium.
A TWO EMULSION AUTORADIOGRAPHIC TECHNIQUE AND THE DISCRIMINATION OF THE THREE DIFFERENT TYPES OF LABELLING AFTER DOUBLE LABELLING WITH 3H‐ AND WC‐THYMIDINE
Authors: Schultze B. , Maurer W. , Hagenbusch H. 
Published: May 2008

AbstractThe first part of the paper deals with a two emulsion autoradiographic technique for double labelling experiments with 3H‐ and 14C‐thymidine which permits a clear discrimination of the different types of labelling.In the second part the application of this technique to cell kinetic studies is discussed. Accurate discrimination between the different types of labelling, namely purely 3H‐, purely 14C‐ and double (3H +14C) labelling, is only possible if the activity ratio of 3H‐ to 14C‐thymidine is sufficiently high. This condition is necessary for a reliable distinction between those grains in the first emulsion which are due to true 3H‐labelling and spurious grains which are simultaneously produced in the same emulsion by 14C‐β‐particles. Experiments are described to determine the required activity ratio of 3H‐ to 14C‐thymidine.
ALTERATIONS IN 3H‐THYMIDINE INCORPORATION INTO DNA INDUCED BY METHYL CCNU [1‐(2‐CHLOROETHYL)‐3‐(4‐METHYL CYCLOHEXYL)‐1‐NITROSOUREA] IN NORMAL AND TUMOROUS TISSUES IN VIVO
Authors: Young Robert C. , Goldberg Diana , Grotzinger Karen R. 
Published: May 2008

AbstractMethyl CCNU produces a suppression of tritiated thymidine (3H‐TdR) incorporation into DNA in vivo in normal bone marrow and gastrointestinal tissues which is different in magnitude and duration from that seen in L1210 ascites tumor in the same animals. This suppression and recovery pattern is not seen in animals bearing L1210 ascites tumor resistant to MeCCNU. Where a different pattern of recovery is seen between normal host target tissues and tumor, the pattern can be exploited to increase the cure rate of animals bearing advanced L1210 ascites tumor with properly spaced second doses of MeCCNU. Additional information on the potential toxicity of second doses of MeCCNU can be predicted from knowledge of the time of recovery of DNA synthesis in the normal host target tissues.
PROPERTIES OF G0 CELLS: VARIATIONS IN THE PROLIFERATIVE RESPONSE FOLLOWING ISOPRENALINE
Authors: Radley J. M. , Hodgson G. S. , Koschel K. W. 
Published: May 2008

AbstractThe proliferative behaviour induced in the acinar cells of the rat submaxillary gland in response to isoprenaline has been used to examine the transit time of cells from a quiescent (G0) state into the S phase. Cumulative 3H‐TdR labelling index curves were constructed to determine the mean time interval (Gis time) between stimulation with isoprenaline and entry into the S phase. Data were collected for the proliferative wave induced by three sequential injections of isoprenaline, and the effects of varying the interval between the second and third injections of isoprenaline, and of changing the dose of the drug, were examined. Intervals of 28, 52 and 76 hr between isoprenaline injections resulted in mean Gis times of 16‐2, 20‐9 and 25‐6 hr respectively. It was concluded that the Gis time depended on the recent history of cells with respect to stimulation, but not division. The results are considered in terms of two models, in one of which the time to leave G0 is variable, whilst in the other the cells leave G0 immediately the stimulus is applied.
EXTRACELLULAR STIMULATION OF EPIDERMAL DNA SYNTHESIS
Authors: ROTHBERG S. , Nancarrow Grace E. , Meydrech E. F. , Iwanik M. J. 
Published: May 2008

AbstractThe removal of the topmost cell layers of the epidermal stratum corneum by stripping initiates a series of biochemical events which alters the normal homeostatic control of and results in the acceleration of the cell cycle in basal cells which are ten to twenty cell layers removed from the site of stripping. One measure of accelerated events is a stimulation of thymidine incorporation into epidermal DNA at time intervals following stripping. Two peaks of maximal stimulation occur between 12 and 24 hr and 48 and 54 hr after stripping.Stimulation of thymidine incorporation into epidermal DNA by limited stripping is a useful technique for studying the stripping‐initiated signal at the stratum corneum and its subsequent translation at the proliferative cell receptor site.