bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECT OF CYCLOPHOSPHAMIDE ON THE HEMATOPOIETIC MICROENVIRONMENTAL FACTORS WHICH INFLUENCE HEMATOPOIETIC STEM CELL PROLIFERATION
Authors: Fried W. , Husseini S. , Gregory S. , Knospe W. H. , Trobaugh F. E. 
Published: May 2008

ABSTRACTTransplanted hematopoietic stem cells (HSC) regenerate more rapidly in the femoral marrow of lethally irradiated hosts pretreated with cyclophosphamide (CY) 4 days prior to X‐irradiation than they do in that of uninjected irradiated hosts (control). On the other hand, regeneration of HSC transplanted into irradiated hosts given CY 7 days before X‐irradiation is slower than in controls.The microenvironment in the femoral marrow was studied at various times after giving CY. Four days after injecting CY, the number of colony forming units (CFU), total nucleated hematopoietic cells, and mature myeloid and erythroid cells in the femoral marrow is markedly reduced. Seven days after injecting CY, the number of CFU in the femoral marrow is still reduced, the total nucleated cell count is back to normal, but the number of mature myeloid elements in the marrow are significantly increased. These observations suggest the conclusion that the rate of proliferation of HSC is modulated by the number of mature myeloid cells in the microenvironment.
CELL PROLIFERATION IN THE CASTRATE MOUSE SEMINAL VESICLE IN RESPONSE TO TESTOSTERONE PROPIONATE
Authors: Morley Adrian R. , Wright Nicholas A. , Appleton David 
Published: May 2008

ABSTRACTThe cell proliferation kinetics following induced DNA synthesis in the mouse seminal vesicle were measured after treatment with testosterone propionate. Fraction labelled mitosis curves at 24, 48 and 72 hr after injection gave t2 values of 1·5, 2·0 and 1·8 hr respectively, and ts values of 10·5, 8·0 and 8·0 hr. Tc measured 48 hr after stimulation was 17·5 hr. Growth fraction rose from 0·14 at 24 hr to 0·64 at 48 hr, and fell to 0·32 by 72 hr. A simple model is proposed in which the rise and fall of mitotic index and labelled index is determined by the ‘cell distribution ratio’.
SPERMATOGONIAL STEM CELL RENEWAL IN THE MOUSE: I. NORMAL SITUATION
Authors: de Rooij D. G. 
Published: May 2008

ABSTRACTSpermatogenesis in the mouse has been investigated by counting the different kinds of spermatogonia throughout the cycle of the seminiferous epithelium. A description is given of the Aisolated (Ais), Apaired (Apr) and Aaligned (Aal) spermatogonia and the other A spermatogonia as they appear in tubules mounted in toto. This technique enabled Ais, Apr and Aal spermatogonia to be counted.Our results complete the evidence for the concept of a population of morphologically undifferentiated A spermatogonia preceding the A1 spermatogonia in the line of spermatogenesis and that among these A spermatogonia, the Ais cells are to be regarded as the stem cells of spermatogenesis.In population of Ais, Apr and Aal spermatogonia divisions take place during the life spans of A2, A4 and In spermatogonia and also rarely during the life span of B spermatogonia. During the life spans of In and B spermatogonia the Aal gradually differentiate into A1 spermatogonia. About 10% of the total number of A spermatogonia in stages 7–8, mainly Aisolated and some Apaired, do not differentiate but start a new multiplication cycle.
THE ALTERATION OF THE REGENERATIVE ACTIVITY AND THE CELL CYCLE OF PARTIALLY HEPATECTOMIZED RAT LIVER FOLLOWING ADMINISTRATION OF d‐GALACTOSAMINE
Authors: Lesch R. , Bachmann W. , Reutter W. 
Published: May 2008

ABSTRACTA single injection of d‐galactosamine given to rats at different times after partial hepatectomy (PH) changes the pattern of regenerative proliferation. When administered during the pre‐replicative phase of regeneration, the onset of DNA synthesis and the increase in labelling index after injection of 3H‐thymidine are delayed by about 12 hr. The injection of d‐galactosamine at 24 hr after PH inhibits the drop in DNA synthesis occurring normally during the following 12 hr period. This was detected by a high labelling index and by an increased specific activity of DNA. The findings indicate a lengthening of the S phase, while G2 and M remain normal. Two modes of action of d‐galactosamine on the cell cycle are discussed.
EFFECTS OF HYDROXYUREA AND RADIATION ON HAIR MATRIX CELLS
Authors: Malkinson F. D. , Griem M. L. , Marianovic R. 
Published: May 2008

ABSTRACTInvestigations were undertaken in CF1 mice to study the effects of hydroxyurea (HU) on hair matrix cell kinetics, and to assess the effects of combined administration of HU and irradiation on induction of temporary alopecia. HU 100 mg/kg was administered intraperitoneally and each animal received tritiated thymidine 0·5 μCi/g 30 min before biopsy. Serial biopsies were taken up to 48 hr after drug administration. Autoradiographs of anagen follicle squashes revealed sharp reductions in mitotic and labeling indices within 30 min. Depressed mitotic indices of 0·6–0·9% at 1–4 hr returned to normal (2·3%) after 6 hr, followed by cyclic mitotic ‘overshoot’, and were preceded by parallel changes in the labeling indices. HU‐induced cellular damage was most marked 4 hr after HU injection, with almost complete recovery from injury observed at the 24 hr interval.The effects of varying the time intervals from 1 to 12 hr between HU administration and irradiation (650 rads) after injection of HU 1200 mg/kg were examined. Hair loss was measured 7 days later by photomicroscopy. Cyclic maximum alopecia was found at the 1–5 and 8–12 hr intervals, with relative ‘protection’ occurring at the 6–7 hr time periods.
SYNCHRONIZATION OF BABY RAT HEPATOCYTES: A NEW TEST FOR THE DETECTION OF FACTORS CONTROLLING DNA SYNTHESIS IN RAT HEPATIC CELLS
Authors: Nadal C. 
Published: May 2008

ABSTRACTThe subcutaneous injection of irritating substances to baby rats results in a very reproducible wave of synchronized S phase DNA synthesis in hepatic cell involving 20% of the total population. Use has been made of this reaction to detect factors affecting DNA synthesis in hepatic cells. It enables substances to be tested during precise periods of the cell cycle. Two activities which were detected in normal adult rat serum, could not be found in the serum of the baby rat or of the partially hepatectomized adult rat: an activity inhibiting the progression of hepatocytes through the cell cycle in the late G1 phase, and an activity inducing the production of binucleate hepatocytes, effective in the late G1 and in the S phase.
MALL LYMPHOCYTE POPULATIONS IN THE MOUSE BONE MARROW
Authors: Röpke C. , Everett N. B. 
Published: May 2008

ABSTRACTAutoradiography and scintillation counting have been used for evaluation of lymphocyte turnover and life span in the bone marrow, peripheral blood and thoracic duct lymph of BALB/C mice. It was shown that the bone marrow contained two populations of small lymphocytes. One population was labelled 100% after 3–4 days of intensive injections of 3H‐thymidine and constituted about 75% of the lymphocytes. The remaining 25% of the lymphocytes turned over at a much slower rate comparable to the rate of increase in labelled small lymphocytes of the thoracic duct. More than 10% of the small lymphocytes of the bone marrow were found to be unlabelled after 10 days of intensive injections of 3H‐thymidine. Nine weeks after giving 3H‐thymidine for 30 consecutive days, 8·6% of the small lymphocytes in the bone marrow remained labelled. The mean grain counts of cells in this population were comparable to those of thoracic duct lymphocytes at corresponding times. About 90% of the peripheral blood lymphocytes were found to have a slow turnover and a long life span.
FURTHER OBSERVATIONS ON THE LATE LABELLING ASSOCIATED WITH STIMULUS‐RESPONSIVE CELLS IN SKIN
Authors: Potten Christopher S. 
Published: May 2008

ABSTRACTThe presence of a long‐lived DNA precursor pool which may show some specificity for stimulus‐responsive cells has been demonstrated. Autoradiography, biochemical analysis, hydroxyurea sensitivity, and the temporal response all suggest that the late incorporation is into DNA in cells in the basal layer of the skin that respond to stimulation. The effect is observed with various doses of tritiated thymidine and both methyl and 6 labelled material. 125Iododeoxyuridine also shows late labelling in skin. It is believed that the late labelling is readily distinguishable from reutilization and from possible slow utilization of catabolites into molecules other than DNA. Skin of the ear and dorsum shows similar degrees of late incorporation, while tail and foot skin apparently have smaller long‐lived pools. This may indicate smaller stimulus‐responsive cell populations. If tritiated thymidine is given to cells after stimulation there is still some slow or delayed uptake. The distribution of labelled cells in the autoradiographs suggests that the late labelling cells may be associated somehow with pre‐existing labelled cells (cells in S at the time of thymidine administration).
CELL POPULATION KINETICS AND DESQUAMATION SKIN REACTIONS IN PLUCKED AND UNPLUCKED MOUSE SKIN
Authors: Hegazy M. A. H. , Fowler J. F. 
Published: May 2008

ABSTRACTThe kinetics of cellular proliferation in plucked and unplucked dorsal skin of mice after local X‐irradiation are described, in relation to the time course of the gross desquamation reaction in skin of the dorsum and of the foot.
THE EFFECT OF ACUTE RENAL FAILURE ON MITOTIC DURATION OF MOUSE ILEAL EPITHELIUM
Authors: McDermott F. T. , Dalton M. K. , Galbraith A. J. 
Published: May 2008

ABSTRACTPrevious percentage labelled mitoses studies in acutely uraemic mice have demonstrated a lengthening of the cell cycle and the DNA synthetic phase of ileal epithelium. The mitotic index was unaltered. Further studies have been performed to obtain an estimate of mitotic duration.Acute renal failure was produced by urinary outflow obstruction in male mice. Controls were subjected to sham operation. The mean number of cells per crypt cell column, number of mitoses present per crypt section and differential mitotic stage count were assessed 18 hr after operation for uraemic and control mice. The mean number of metaphases accumulated per crypt section over a 2 hr interval following colchicine injection was obtained in other groups of mice and the mitotic duration calculated.The mean number of mitoses per crypt section was 1.30 ± 0.46 for the controls and 1.48 ± 0.66 for the uraemic group. No evidence for a block in mitosis was indicated by the differential mitotic stage count. After applying Tannock's correction factor the mitotic duration was estimated to be 0.91 ± 0.18 hr for the control group and 2.81 ± 0.89 hr for the uraemic group. The difference in duration between the groups, 1.90 ± 0.91 hr, was significant (P≤0.05).Reduction in cell proliferation may explain the development of uraemic lesions in the gastrointestinal tract.
DISSECTING THE HEMATOPOIETIC MICROENVIRONMENT. I. STEM CELL LODGMENT AND COMMITMENT, AND THE PROLIFERATION AND DIFFERENTIATION OF ERYTHROPOIETIC DESCENDANTS IN THE Sl/Sld MOUSE
Authors: Wolf Norman S. 
Published: May 2008

ABSTRACTThe anemic Sl/Sld mouse and its normal (+/+) congenic control were used to explore the possibility of stromal control over four phases of erythropoiesis: CFU lodgment, commitment of multipotent stem cells to the erythropoietic line, proliferation of stem cells and their descendants, and the differentiation of those descendants into successively more mature forms. Lodgment was found to be the same in the Sl/Sld as in the normal mouse, but commitment, although characteristically different for spleen compared to the bone marrow, was subnormal. The stimulus to proliferate, as measured by spleen colony size and cell type content, was even more reduced. It is suggested that the direct control of differentiation into more mature cells may not be under stromal control.
TURNOVER OF CELL‐RENEWING POPULATIONS UNDERGOING CIRCADIAN RHYTHMS IN CELL PROLIFERATION
Authors: Izquierdo Jorge N. , Gibbs S. Julian 
Published: May 2008

ABSTRACTEvidence is presented in support of the concept of partial synchrony of cells as the cause for circadian rhythms in DNA synthesis and mitotic activity. The nonuniform age distribution of cells in cycle indicated that equations based on total asynchrony were not applicable for calculation of cytokinetic parameters in cellrenewing populations undergoing circadian rhythms. The integration of the circadian mitotic curve is introduced as a simple and accurate method for determination of proliferation rate and turnover time. An approximately linear increase in the labeling index following repeated injections of 3H‐thymidine demonstrated that nearly 100% basal cells in hamster cheek pouch epithelia were in cycle during a turnover time. These experiments suggest that if there is a G2 phase in cellrenewing tissues, this is short with respect to turnover time and that it may be a specific compartment where the control of cell proliferation operates.
THE INFLUENCE OF ADRENORECEPTOR ACTIVITY ON CRYPT CELL PROLIFERATION IN THE RAT JEJUNUM
Authors: Tutton P. J. M. , Helme R. D. 
Published: May 2008

ABSTRACTThe influence of adrenergic stimulation, adrenergic blockade and sympathectomy on crypt cell cycle time and mitotic time in rat jejunum was studied.Alpha adrenergic stimulation by noradrenaline was found to shorten both cell cycle and mitotic times, whereas beta adrenergic stimulation by adrenaline or isoprenaline was found to prolong both cell cycle and mitotic times. Conversely, alpha adrenergic blockade by phentolamine prolonged cell cycle time and beta adrenergic blockade by propranolol or practolol shortened cell cycle time but not mitotic time.Both chemical and surgical sympathectomy inhibited crypt cell proliferation. Chemically sympathectomized animals manifested supersensitivity to exogenous noradrenaline.
MIGRATION OF SMALL LYMPHOCYTES IN ADULT MICE DEMONSTRATED BY PARABIOSIS
Authors: Röpke C. , Everett N. B. 
Published: May 2008

ABSTRACTParabiotic BALB/C mice were used to study the traffic of small lymphocytes in immunological mature but unchallenged mice.By giving 3H‐thymidine (3H‐TdR) injections to only one member (A) of a pair by preventing the escape of the radioactive isotope to the other member (B), the kinetics of newly‐formed cells was followed.Less than 10% labelled small lymphocytes were found in the peripheral lymphoid tissues of both A and B members, while the thymusses and bone marrows of A members showed labelling percentages up to 70% in this period. Hardly any labelled cells gained entrance into the thymus while a detectable number was found in the bone marrows of B members.Results from pairs set up to follow migration of long‐lived lymphocytes revealed that labelled cells detected 4–5 weeks after injections were equilibrated between the peripheral tissues and the bone marrows of the partners. Very few labelled cells were seen in the thymic medulla and none were observed in the thymic cortex, germinal centres or medullary cords of lymph nodes from any B member.It was concluded that short‐lived small lymphocytes are formed primarily in the thymus and bone marrow and the migration of these cells is limited in adult animals. Furthermore, the vast majority of long‐lived small lymphocytes are freely recirculating, and these cells gain entrance to and are normal residents in the bone marrow.
CLEARANCE RATE OF EXOGENOUS 3H‐THYMIDINE FROM THE PLASMA OF PREGNANT RHESUS MONKEYS
Authors: Nowakowski Richard S. , Rakic Pasko 
Published: May 2008

ABSTRACTThe plasma clearance rate of 3H‐TdR was determined by thin‐layer chromatography of samples from pregnant rhesus monkeys who had received a single intravenous injection of 3H‐TdR. At 10 min after the injection the circulating levels of 3H‐TdR had fallen to less than 0.2% of the initial theoretical distribution of the label. In general the plasma clearance rate can be described by a ‘double exponential’curve with half‐lives of 1 min and 20 min. Thus, 3H‐TdR disappears from the circulation of the pregnant monkey more rapidly than it does from the bloodstream of rodents, which correlates with previously detected interspecies differences in autoradiographic labeling of neurons. This means (1) that higher doses of 3H‐TdR must be used for autoradiographic labeling of monkey tissues and (2) that the monkey may be useful for studying cell kinetics because it has a short pulse labeling of the DNA.
DAILY VARIATIONS OF MARROW AND SPLENIC ERYTHROPOIESIS, PINNA EPIDERMAL CELL MITOSIS AND PHYSICAL ACTIVITY IN C57Bl/6J MICE
Authors: Sharkis Saul J. , Palmer John D. , Goodenough Judith , LoBue Joseph , Gordon Albert S. 
Published: May 2008

ABSTRACTRegular daily fluctuations in spontaneous physical activity and in the mitotic indices of marrow and splenic erythroid elements and pinna cells, were observed. Both male and female C57Bl/6J mice showed these rhythms. Of particular interest was the finding that the spleen and the marrow mitotic activity showed a reciprocal relationship. The role of several hormones and the biological clock in control of these rhythms are discussed.
CELL KINETICS IN THE SEBACEOUS GLANDS OF THE MOUSE. I. THE GLANDS IN RESTING SKIN
Authors: Hamilton E. 
Published: May 2008

ABSTRACTCell proliferation, differentiation and migration have been studied in the sebaceous glands of DBA‐2 mice in the resting (telogen) phase of hair growth. Cells labelled by a single injection of tritiated thymidine start to leave the glands of adult male mice 5 days later. About 80% of the proliferative cells in the basal layer have a cell cycle time of 40 hr or less. In 18% of the proliferative cells G1 is at least 4 days long and 16% have a G2 phase longer than 17 hr. The S phase is about 7.5 hr long and cells spend at least 21 hr in the basal layer before migrating into the differentiating cell region. The glands of mature female and immature mice are smaller than those of the mature male. They have fewer, smaller cells and a much lower labelling index.
QUANTITATIVE IN VITRO STUDIES ON STIMULATION OF MURINE HAEMOPOIETIC CELLS BY COLONY STIMULATING FACTOR
Authors: Van Den Engh Gerrit J. 
Published: May 2008

ABSTRACTA new standardization method for Colony Stimulating Factor (CSF) is described and criteria are introduced which enables stimulating activity to be assessed independent of absolute colony numbers. With this method CSF preparations from different sources are compared and evidence is presented that suggests an identical mechanism of action for these substances. Data are presented on the increase in colony numbers that is induced by the addition of erythrocyte lysates to the cultures. The relationship between colony forming cells that are stimulated by CSF alone and cells stimulated by the combined action of CSF and erythrocyte lysate is discussed.
ESTIMATION OF THE MEAN AND VARIANCE OF CYCLE TIMES IN CINEMICROGRAPHICALLY RECORDED CELL POPULATIONS DURING BALANCED EXPONENTIAL GROWTH
Authors: Jagers Peter , Norrby Klas 
Published: May 2008

ABSTRACTThe mathematical and statistical problem of estimating the mean and variance of cell cycle times from cinemicrographically observed durations until mitosis (cytokinesis at late anaphase), disintegration, collision (cells superimposing each other) or emigration (moving out of the field of vision) of randomly chosen individual cells in a population in balanced exponential growth is treated. The resulting formulae are simple and considerably reduce the average cell observation time. They are applied to two normal human foetal cell lines and their SV40‐transformed counterparts. One result is that the latter seem to have longer cycle times in spite of their shorter doubling times. Another result is that the cell mobility seems somewhat increased in the transformed populations. This corroborates earlier findings, indicating that the extent of cell loss, rather than the length of cycle times, may play a decisive role for the (net) doubling time of cultivated cell populations.
CONTROL OF INTESTINAL EPITHELIAL REPLACEMENT: LACK OF EVIDENCE FOR A TISSUE‐SPECIFIC BLOOD‐BORNE FACTOR
Authors: Clarke Rufus M. 
Published: May 2008

ABSTRACTThe small intestine of rats was cut across in two places, about 14 and 50% of the length of the small intestine from the pylorus, and continuity was re‐established by suturing the proximal and distal ends. The resulting sac of small intestine, averaging 36% of the total length of the small intestine, had its upper end closed off, and its lower end anastomosed, either to the intestine‐in‐continuity (an ‘intestine‐sac’), or to the skin of the abdominal wall (a ‘skin‐sac’).On the ninth post‐operative day, the cell production rate in squashes of micro‐dissected whole crypts of Lieberkühn was measured by mitotic blockade with Colcemid. The rate of cell production in unoperated and sham‐operated rats was 30 cells/crypt/hr, throughout the length of the small intestine. In the intestine in continuity, the rate increased to an average of 46 cells/crypt/hr above the anastomosis, and to 54 cells/crypt/hr below it. At the lower end of the ‘intestine‐sac’, which drained into the intestine‐in‐continuity, the rate was 39 cells/crypt/hr, while in the lower end of the sac which drained to skin the rate of cell production was only 16 cells/crypt/hr. This significantly lower cell production rate in intestine which was not in contact with ingesta is taken to be evidence of the importance of local, rather than blood‐borne factors in the control of epithelial replacement.
SOME PROPERTIES OF A ‘Go’ MODEL OF THE CELL CYCLE
Authors: Maertelaer V. De , Galand P. 
Published: May 2008

AbstractSome models describing the kinetics of cell proliferation present the major advantage of requiring a small set of parameters for the complete description of the kinetic behaviour of cell populations. Among such models, that proposed by Burns & Tannock (1970) offers the further advantage of allowing a generalized description of cell cycle that covers the ‘Go’ concept.This model assumes that the cell life cycle consists of two phases: G‐phase and C‐phase. After division, the cells enter G‐phase and remain there for any length of time. They leave this phase at a constant rate (kG) to enter C‐phase where they divide. C‐phase has a constant duration: θ. Only the two parameters θ and kG are required for a complete kinetic description in the steady‐state case. This is also true for an exponentially growing population, provided cell loss is null or negligible.We started from the equations relating kG, θ and NG/N (where NG is the number of cells in G‐phase and N the total cell numbers) associated with the following models:(1) Burns & Tannock (1970) model based on the hypothesis that the cells may differentiate from any phase of the cell cycle.(2) A variant of this model where only the cells in G‐phase may differentiate. We describe an original method allowing the determination of the parametersof the model from published ‘labelled mitosis’ curves. We observe that the experimentally obtained values of those parameters constitute a non‐randomly limited part of the set of values that one may theoretically have. This suggests the necessity for further assumption(s) restricting the model.
ACTIVITY OF TUBULOSINE ON THE KINETICS OF ROOT MERISTEM CELL POPULATION
Authors: Pareyre Claude , Deysson Guy 
Published: May 2008

AbstractThe action of tubulosine on the mitotic cycle was studied using continuous labelling with tritiated thymidine. This alkaloid provokes a lengthening of the G1 and S phases and a blocking of G2 is totally reversible when the treatment is followed by recovery in normal medium.At a dose of tubulosine which induces a reversible mitostasis in the shortest possible time the lengthening of the phases of the cell cycle was estimated by three different techniques: labelled mitoses for the determination of G2; labelling intensity for the determination of S; binucleate cells for the determination of T, and an original technique using labelling index of binucleate cells for the determination of G1.The limits of the technique of labelled mitosis together with the interest of the technique aiming at the direct determination of G1 in the case of a perturbed cycle are then discussed.