bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rat C‐6 Glioma Cells Maintained In an Organ Culture System: A Study of Kinetic Parameters
Authors: Halks‐Miller M. , Miller R. G. , Rubinstein L. J. 
Published: May 2008

ABSTRACTRat C‐6 glioma cells were grown on a sponge foam matrix in an organ culture system and the cell cycle parameters, including the growth fraction (GF), were assessed after autoradiography. the zones of growth consisted of a compact upper layer (UL) at the gaseous interface, a central necrotic layer and a deeper lower layer (LL) which invaded the matrix. the fraction of continuously labeled mitoses (FCLM) was similar in both the UL and LL cells. the derivatives of the FCLM curves obtained in three experiments gave an average modal TG2 of 5 hr. A mathematical model relating GF, TG2, TC and labeling index as a function of time, LI(t), was devised for cells in a steady state exposed continuously to tritiated thymidine and was applied to data obtained from UL cells. A mean GF of 9% (range: 8–10%) and a mean cell cycle time (TC') of 27 hr (range: 13–47 hr) were obtained. the mean TS was calculated to be 11 hr (range: 8–16 hr) by the method of grain counts per mitotic figure or grain index (GI). Knowledge of TS permitted alternative calculation of the cell cycle time from the equation TS/TC= LI(0)/GF: this gave a mean cell cycle time (TC) of 29 hr (range: 20–45 hr).Except for the GF, the cell kinetics were comparable to those of the same cell line grown in monolayer culture. the GF in the in vitro system described is in the lower range reported in some human malignant gliomas in vivo.
ON THE DERIVATION OF CELL KINETICS FROM HISTOMORPHOLOGY, OBSERVED IN THE RAT INCISOR ODONTOBLAST
Authors: Michaeli Y. , Pitaru S. , Zajicek G. 
Published: May 2008

ABSTRACTA method to extract cell kinetic information from histomorphology is presented. Each replicating tissue is essentially an ordered structure with an origin where cells are formed and a periphery toward which they are displaced. the displacement path is called the tissue radius. the tissue variables may be studied in two domains, space and time. the first embraces all the states a cell may assume while the second specifies the cell transition rates. During steady state both domains are related linearly.These ideas are illustrated in the rat incisor odontoblast population whose life expectation is determined by the tooth wall shape. the odontoblast cell population paves the interior of the tooth wall delimiting a cone‐shaped pulp. Near the root apex the dentine wall is barely visible. As one proceeds distally, the wall thickens while the pulp narrows. Pulp narrowing is associated with odontoblast cell loss whose magnitude may be deduced from the change of the pulp circumference CI(x) (x is the distance from tooth origin). the odontoblast force of mortality μ(x) may be calculated from the instantaneous perimeter change: μ(x) = ‐CI' (x)/CI(x); where CI'(x) stands for the derivative of CI(x). This equation serves for the construction of the odontoblast life table which may be studied in space and time.
Genetic Control of Lipopolysaccharide‐Induced Mobilization of Cfus Dissociation Between Early and Delayed Mobilization of Cfus In Complement C5‐Deficient Mice and Lps Non‐Responder Mice
Authors: BENNER R. , RIJNBEEK A.‐M. , Molendijk W. , Vos O. 
Published: May 2008

ABSTRACTLipopolysaccharide (LPS)‐induced mobilization of CFUs from haemopoietic tissues into the circulation has a biphasic pattern. the first rise occurs within 30 min of LPS injection, the second 4–7 days later. This second rise coincides with an increase of the CFUs number in the spleen from about 3000 to about 50,000. We have investigated the relationship between the two peaks by making use of complement C5‐deficient mouse strains and the LPS non‐responder mouse strains C3H/HeJ and C57BL/10ScCr. These latter two strains lack a serologically identifiable structure (‘LPS‐receptor’) which is present in all LPS‐responder strains.After injection of eleven different mouse strains with LPS, the numbers of circulating CFUs increased rapidly in all strains, except in the C5‐deficient A/J, AKR/J, DBA/2J and B10.D2/oSn mice. On the other hand, the delayed LPS‐induced accumulation of CFUs in blood and spleen occurred in all mouse strains tested, including the C5‐deficient strains, but not in the LPS non‐responder strains C3H/HeJ and C57BL/10ScCr. These results show that (a) early LPS‐induced mobilization of CFUs is dependent on the availability of C5, in contrast to the delayed CFUs accumulation in blood and spleen, (b) the presence of the LPS receptor is not required for early CFUs mobilization by LPS and (c) recognition of the mobilizing agent by a specific receptor is required for the delayed accumulation of CFUs in blood and spleen.
Post‐Irradiation Thymocyte Regeneration After Bone Marrow Transplantation I. Regeneration and Quantification of Thymocyte Progenitor Cells In the Bone Marrow
Authors: Boersma W. , Betel I. , Daculsi R. , van der Westen G. 
Published: May 2008

ABSTRACTGrowth kinetics of the donor‐type thymus cell population after transplantation of bone marrow into irradiated syngeneic recipient mice is biphasic. During the first rapid phase of regeneration, lasting until day 19 after transplantation, the rate of development of the donor cells is independent of the number of bone marrow cells inoculated. the second slow phase is observed only when low numbers of bone marrow cells (2.5 × 104) are transplanted. the decrease in the rate of development is attributed to an efflux of donor cells from the thymus because, at the same time, the first immunologically competent cells are found in spleen. After bone marrow transplantation the regeneration of thymocyte progenitor cells in the marrow is delayed when compared to regeneration of CFUs. Therefore, regenerating marrow has a greatly reduced capacity to restore the thymus cell population. One week after transplantation of 3 × 106 cells, 1% of normal capacity of bone marrow is found. It is concluded that the regenerating thymus cells population after bone marrow transplantation is composed of the direct progeny of precursor cells in the inoculum.
Haematopoiesis In Mice Heterozygous For the W Trait: Defective Formation of Transient Endogenous Spleen Colonies
Authors: Wiktor‐Jedrzejczak W. , Szczylik C. , Górnas P. , Sharkis S. J. , Ahmed A. 
Published: May 2008

ABSTRACTIt has been determined that W/+ and Wv/+ heterozygous mice, as compared with normal +/+ homozygous littermates, form significantly lower numbers of transient 5‐day endogenous spleen colonies in response to X‐irradiation. This defect was evident for doses of irradiation between 2–6 Gy (200–600 rad) and was associated with a slightly increased radiosensitivity of the assayed precursor cells (TE‐CFU) in W heterozygotic mice. Moreover, the defect was transplantable, i.e., intrinsic to the marrow cells and not to the microenvironment, and was not associated with a similar decrease in cells which form erythropoietic bursts in vitro (BFUe). This study provides a cellular basis for increased radiosensitivity of W/+ and Wv/+ mice and suggests that the ‘W’ mutation is semi‐dominant, both with respect to the white spotting and TE‐CFU formation.
Leukocyte Mobilization In Mice By Polyanions Decline of Leukocyte Mobilizing Capacity After Transplantation of Lymphoma
Authors: Benner R. , Nikkels P. G. J. , van Oudenaren A. , Wolters E. A. J. 
Published: May 2008

ABSTRACTThe leukocyte mobilizing polyanions dextran sulphate (DS) and polymethacrylic acid (PMAA) were administered to AKR and (C57BL × CBA) F1 mice at various times after transplantation of syngeneic lymphoma cells. In nonleukaemic mice DS and PMAA increased the number of circulating leukocytes 3–4‐fold. the extent of leukocyte mobilization in leukaemic mice depended on the interval between transplantation of the lymphoma cells and injection of the polyanion. During the development of leukaemia in AKR as well as in (C57BL × CBA) F1 mice the capacity to react upon injection of polyanions with leukocyte mobilization gradually decreased. For DS, this decrease started before the number of leukocytes increased in the peripheral blood. On the other hand, the capacity for PMAA‐induced leukocyte mobilization was fully preserved for several more days. In heavily leukaemic mice neither DS nor PMAA could further increase the number of peripheral blood leukocytes. In such mice the distribution pattern of leukaemic blast cells, small lymphocytes, granulocytes and monocytes was also hardly or not affected by injection of the polyanion.
Decreased Sensitivity to Hydroxyurea and to [3H]Thymidine Suicide In the Middle of the S Phase
Authors: Nečas E. , Poňka P. , Neuwirt J. 
Published: May 2008

ABSTRACTPluripotent haemopoietic stem cells (CFUs) move synchronously through the cell cycle in hydroxyurea‐treated mice in a cohort 1–2 hr broad. Ten to fifteen hours after hydroxyurea they pass through S phase. DNA synthesis appears to be depressed 5–10 times when the cells are in the middle part of the S phase but does not seem to be completely interrupted. High concentrations of [3H]thymidine must be used for ‘suicide’ in order to achieve lethality for the cells with depressed DNA synthesis. At the time when DNA synthesis is depressed, the sensitivity of the cells to hydroxyurea also decreases. This may lead to a significant underestimation of the S phase fraction by the hydroxyurea method, because CFUs with low DNA synthesis rate are resistant to hydroxyurea although being in S phase.
SUPPRESSION OF SERUM OR LIVER CYTOSOL‐INDUCED G1‐S BLOCK IN BABY RAT HEPATOCYTES BY A PROTEASE ANTAGONIST: THE KUNITZ FACTOR
Authors: Nadal C. , Le Rumeur E. 
Published: May 2008

ABSTRACTThe Kunitz factor did not modify hepatocyte synchronization obtained in baby rats after inflammatory stimulation but abolished the G1‐S block induced by adult rat serum or liver cytosol. This effect was dose‐dependent. the Kunitz factor was only active during the hour preceding serum or liver cytosol injection.
An Improved Sum‐Of‐Normals Technique For Cell Cycle Distribution Analysis of Flow Cytometric Dna Histograms
Authors: Jett J. H. , Gurley L. R. 
Published: May 2008

ABSTRACTAn improved method for determining the fraction of cells in the G1, S and G2+ M phases of the life cycle, from DNA distributions of S phase rich cultures, is presented. Picolinic acid synchronized cell cultures were used to demonstrate the usefulness of the technique for the cell cycle distribution analysis. the algorithm presented quantifies DNA histograms from FCM analyses using an extension of the previously reported ‘sum of discrete normal curves’ technique. It alleviates problems encountered with earlier methods by extending the contribution of the S phase cells to the distribution under the G1 and G2+ M peaks; at the same time it allows more of the descriptive parameters to be determined from the individual histograms. the fractions of cells in the G1, S, and G2+ M phases of the life cycle obtained by this method compare favourably with autoradiographic analyses and other analytical results.
REGULATION OF HUMAN MYELOPOIESIS BY PROSTAGLANDIN E AND LACTOFERRIN
Authors: Pelus L. M. , Broxmeyer H. E. , Moore M. A. S. 
Published: May 2008

ABSTRACTStudies on human myeloid stem cell proliferation indicate that progenitor cell populations committed to monocytoid differentiation are preferentially inhibited by prostaglandin E (PGE). the addition of PGE but not PGF to day 7 CFUGM cultures upon initiation results in the dose‐dependent inhibition of total colony and cluster formation. Morpholigical analysis of proliferating clones demonstrates that the effect of PGE on total colony and cluster formation results from the selective inhibition of monocyte‐macrophage colony forming cells. Mixed monocytoid/neutrophil colony formation was markedly less sensitive and neutrophil and eosinophil colony formation essentially insensitive to the inhibitory effects of PGE. the inhibition of monocytoid colony formation by PGE1 extends equally well to day 13 CFUGM, but not to CFUGM in suspension culture. the observed effects of PGE1 on monocytoid committed pre‐CFUGM and day 7 and day 14 CFUGM indicate that sensitivity to inhibition by PGE increases with progenitor cell maturity. Specificity analysis indicates that prostaglandins of the E series (PGE1, PGE2) are by far the most active naturally occurring prostanoate compounds inhibiting CFUGM proliferation.The addition of iron saturated lactoferrin to liquid cultures of human peripheral blood monocytes, inclusion into mononuclear cell feeder layers or addition to agar cultures proliferating in response to endogenously produced CSFs, results in the equivalent inhibition of CSFs necessary for day 7 and day 14 monocytoid and/or neutrophil and eosinophil colony and cluster formation.These results indicate roles for PGE and lactoferrin in myeloid stem cell regulation in vitro and suggest that they may serve as physiological regulators of granulocyte and monocyte proliferation.
The Effect of X‐Irradiation On Cell Loss In Five Solid Murine Tumours, As Determined By the 125Iudr Method
Authors: Kelley S. D. , Kallman R. F. , Rapacchietta Diane , Franko A. J. 
Published: May 2008

ABSTRACTThe rate of cell loss in irradiated RIF‐1, EMT6, KHJJ, B16 and KHT tumours was studied using the 125IUdR loss technique. Administration of 125IUdR preceded localized tumour irradiation by 2 days. Loss of tumour radioactivity was measured for 6–8 days after irradiation. the blood flow to some tumours was occluded during, and for 30 min following, injection of the label to measure the amount of radioactivity entering the tumour as a result of reutilization of label from the gut epithelia and influx of labelled host cells. Irradiation did not significantly alter the amount of radioactivity entering these clamped tumours during the 8–10 days after injection of 125IUdR. This permitted comparison of irradiated and control groups based on the loss of radioactivity from the non‐occluded tumours. Irradiation of RIF‐1, EMT6, KHJJ or B16 tumours with doses of 600, 1400, 2400 or 4400 rads produced no significant increase in the rate of loss of tumour radioactivity. This suggested that, in the population of labelled cells, cell lysis following irradiation proceeded slowly. In contrast, KHT tumours showed a significant increase in loss rate following each radiation dose, although the increase was dose‐independent. In all tumour systems, the constant rate of cell loss after radiation appeared to coincide with published reports of tumour growth responses after irradiation. the present data suggest that the manner of expression of radiation‐induced cell killing results from the cellular proliferative status, i.e. whether a cell is cycling or non‐cycling.
Production of presumptive humoral haematopoietic regulators in canine cyclic haematopoiesis
Authors: Dunn C. D. R. , Jones J. B. , Lange R. D. , Wright E. G. , Moore M. A. S. 
Published: May 2008

Abstract. Conditioned media (CM) were prepared according to previously published techniques from the bone marrow of dogs with cyclic haematopoiesis (CH). CM prepared from day 9 marrows inhibited mouse bone marrow CFU‐s proliferation rate while CM from day 10 marrows were stimulatory and also contained an erythroid stimulating factor which appeared to be erythropoietin. In addition a highly significant trend from CM containing CFU‐s inhibitory materials to media with CFU‐s stimulatory activity was observed through cycles day 1 to 8. These studies further support the concept that CH is due to a defect in factors controlling stem cell proliferation and suggest that a major event occurs in CH dog marrow on days 9 and/or 10 of the cycle.Bone marrow transplantation studies (Dale & Graw, 1974; Weiden et al., 1974; Jones et al., 1975b) have indicated that canine cyclic haematopoiesis (CH) is probably due to a disorder in the multipotential stem cells. Morphological evidence (Scott et al., 1973) and the almost synchronous cycling of CFU‐e, CFU‐c and diffusion chamber progenitor cells (DCPC) (DUM et al., 1977, 1978a, b) lend support to such a theory. However, efforts to identify the mechanisms controlliig multipotential stem cell proliferation in dogs have been handicapped by the lack of suitable techniques to study these cells in the canine. Recently, Wright and co‐workers (Wright & Lord, 1978, 1979; Wright et al., 1979; Lord et al., 1979), on the basis of previous observations (Frindel et al., 1976; Frindel & Guigon, 1977), described the preparation of species non‐specific, bone marrow conditioned media (CM) which are capable of influencing the proliferation rate of murine colony forming units‐spleen (CFU‐s). The studies now reported were designed to determine if CM prepared from canine CH marrow would influence the proliferation rate of murine bone marrow CFU‐s. The results indicate that a major event, possibly related to the in vivo control of stem cell proliferation in dogs with CH, occurs on days 9–10 of the cycle; day 1 being the first day when the peripheral blood neutrophil count falls below‐1600 mm3.
Subclassification of cells in S phase in a partially synchronized cell system
Authors: Møller U. , Keiding N. , Engel F. 
Published: May 2008

Abstract. A circadian dependent delay in the incorporation of [3H]TdR into DNA, presumably due to variations in the intracellular pool of [3H]TdR derivatives, was found. It seems reasonable to relate this effect to a circadianally varying age distribution of cells in S phase.At any given time the S phase cells showed large variations in DNA synthesis rate, but it was still possible to identify a mean diurnal variation in the DNA synthesis rate.Differences in the ability of S phase cells to incorporate [3H]TdR are also discussed in relation to flow cytometrical measurements, and this contributes to the understanding of the commonly observed phenomenon that flow cytometry estimates of S‐fractions are higher than those obtained with autoradiography.
A comparison of mathematical methods for the analysis of DNA histograms obtained by flow cytometry
Authors: Baisch H. , Beck H.‐P. , Christensen I. J. , Hartmann N. R. , Fried J. , Dean P. N. , Gray J. W. , Jett J. H. , Johnston D. A. , White R. A. , Nicolini C. , Zeitz S. , Watson J. V. 
Published: May 2008

Abstract. Twelve methods for analysing FCM‐histograms were compared using the same set of data. Some of the histograms that were analysed were simulated by computer and some were taken from experiments. Simulated data were generated assuming asynchronously growing cell populations and (i) measurement coefficients of variation (CV) from 2 to 16%; (ii) constant measurement CV or CV's increasing from G1 to G2 phase, and (iii) varying fractions of cells in each phase. Simulated data were also generated assuming synchronous cell populations in which a block in early S phase was applied and released. DNA histograms were measured for L‐929 cells at various times after mitotic selection. Labelling indices were also measured for these cells at the same time.The fractions of cells in the G1, S, and (G2+ M) phases were calculated by each analytical method and compared with the actual fractions used for simulation, or in case of experimental data, with autoradiographic results. Generally, all methods yielded reasonably accurate fractions of cells in each phase with relative errors in the range of 10–20%. However, most methods tended to overestimate G1 fractions and underestimate S fractions. In addition, variations in the shape of the S phase distribution often caused considerable errors. Phase fractions were also calculated for histograms of kinetically perturbed populations, simulated as well as experimental The errors were only slightly larger than for histograms from asynchronously growing cell populations.
Cell kinetic studies on the JB‐1 ascites tumour of the mouse
Authors: Müller V. O. , Friede H. , Schultze Brigitte 
Published: May 2008

Abstract. The FLM method, modified by double labelling with [3H]‐ and [14C]‐thymidine, has been applied to the 4‐day old JB‐1 ascites tumour of the mouse. It results in well separated waves of purely [3H]‐ and purely [14C]‐labelled mitoses, which show a remarkable asymmetry with long tails to the right. The following values for the mean transit times of the cells have been derived from this FLM curve, for a tumour age of 4–6 days: TC= 32.5 hr, TS= 16.7 hr, TG1= 3.7 hr, TG1= 11.0 hr and TM= 1.1 hr. A further evaluation of the FLM curve, however, is difficult, due to the non‐stationary growth of the tumour.A number of other experimental findings (growth curve, decrease of the labelling and mitotic index with increasing tumour age, two single‐labelled FLM curves starting 4 and 6 days after tumour inoculation) indicate that the cell cycle time increases during the experimental period of the double‐labelled FLM curve (about 2 days). A lengthening of the cycle time should result in an increasing enlargement of the areas under the waves of the modified FLM curve. However, such an increase in area has not been found; the areas are constant.All the results of the present cell kinetic studies would be consistent if it were postulated that the cell cycle time lengthens with increasing tumour age up to about 4 days after inoculation, then remains relatively constant at between 4 and 6 days and thereafter increases again. Short‐term double labelling experiments suggest that this is actually the case. Under the assumption of nearly constant phase durations during the 5th and 6th day of tumour growth further conclusions can be drawn from the modified FLM curve. In particular, it follows that the transit times of the cells through successive cycle phases are uncorrelated and the variances of the transit times through a cycle phase are proportional to the duration of this phase.
Evidence for the pulmonary origin of alveolar macrophages
Authors: Tarling J. D. , Coggle J. E. 
Published: May 2008

Abstract. This paper supports the hypothesis that some form of pulmonary alveolar macrophage (PAM) production occurs within the lung in the normal steady state. The study involved monitoring the change in number of labelled PAMs following two modes of irradiation‐the first with the thorax being irradiated and the rest of the mouse shielded, the second with the thorax shielded and the body irradiated. Also measurements of monocyte and PAM numbers after a single bone marrow irradiation were carried out. Finally, the labelling indices of monocytes in both control and thorax irradiated mice were measured.Both the number of monocytes and PAMs, along with the labelling indices of monocytes and PAMs after irradiation, indicate the independence of PAMs from a monocyte precursor population, and also provide evidence for a pulmonary origin of PAMs.