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Biomedical subjects

X Ronot

Publications and source records attributed to X Ronot.

At least 55 records · Page 3Linked to original sources
PubMed1986

Mitochondrial uptake of rhodamine 123 by rabbit articular chondrocytes.

Rhodamine 123 was used to stain and analyze by flow cytometry the mitochondria of rabbit articular chondrocytes. Stationary primary cultures and exponentially growing subcultures were compared to enzymatically released chondrocytes from cartilage. The increase in mitochondrial fluorescence, when chondrocytes are transferred from cartilage to culture environment, is suggestive of some change in chondrocyte adaptation and/or differentiation in these conditions.

Animals↗
PubMed1986

G2 arrest, binucleation, and single-parameter DNA flow cytometric analysis.

One important facet of flow cytometry involves the effects of pharmacological agents on cell cycle progression. Comparative G2 fraction perturbations were examined: effects of sodium butyrate on articular chondrocytes, effects of an antineoplastic agent (SOAZ) and an antirheumatic drug (D-penicillamine) on HeLa cells. Even though DNA flow cytometric analysis detects preferentially an induction of G2 arrest, the mode of action of these agents on the cell cycle is different. Sodium butyrate and D-penicillamine lead to an increase of binucleate cells due to cytokinesis perturbation. Because of similar fluorescence intensity, distinguishing G2 from binucleate GO/1 cells is not easily possible using DNA content measurement and reflects a failure of flow cytometry in the detection of binucleate cells. Rapid cell cycle analysis of single cells should contribute greatly to the study of pharmacological interactions, but DNA flow cytometric measurements obtained from cultured cells exposed to certain agents must be cautiously interpreted because those may interact on cytokinesis and induce artefacts in histogram interpretation.

Animals↗
PubMed1986

Mitochondrial analysis in living cells: the use of rhodamine 123 and flow cytometry.

Flow cytometry combines the advantages of microscopy and biochemical analysis in a single highly sensitive technique for a rapid examination of numerous individual living cells. It has become a potent and essential tool in the studies of the physiology of the whole cell and its organelles. Rhodamine 123 is a vital fluorescent dye used in flow cytometry. As it is specifically concentrated in mitochondria because of the transmembrane potential that these organelles maintain in living cells, rhodamine 123 is thus a useful probe for monitoring the abundance and activity of mitochondria. A critical survey of the routine use of rhodamine 123 together with flow cytometry in mitochondrial research is presented.

Animals↗
PubMed1986

Update on the concept of the cell cycle: the contribution of flow cytometry.

Flow cytometry has been extensively used to provide accurate estimates of the relative amounts of various cellular constituents (DNA, RNA, proteins) for cell kinetic studies. Multiparametric analysis also supports the recent concept that cell growth and the DNA division cycle may be under distinct regulatory mechanisms. Moreover, metabolic subcompartments of the cell cycle, distinguished by flow cytometry, have offered a highly sensitive cell classification in comparison with the conventional distinction of the four main phases of the cell cycle. Finally, a new sensitive and powerful technology, BrdU/DNA analysis, represents a remarkable maturing of a very useful alternative for the study of DNA synthesis and cell cycle traverse.

Animals↗
PubMed1986

Applications of flow cytometry in cellular pharmacology.

Cellular pharmacology is defined as the study of drug effects on various cell functions. Flow cytometry enriches cellular pharmacology by the following possibilities for efficient analysis. Firstly, the determination of toxic concentrations can be approached by the assessment of cell viability. However, due to the existence of many fluorescent DNA probes, most studies are devoted to the investigation of products acting on cell division, particularly in the area of antineoplastic drugs. The effects of drugs on respiration can be approached by analysis of mitochondrial activities. On the other hand, the studies of drug actions on cell differentiation functions have been started using antisera or monoclonal antibodies to cell-specific proteins such as collagen and keratin. Flow cytometry appears to be more and more important in the progress of cellular toxicology and pharmacology.

Animals↗
PubMed1986

Modulating effects of drugs on cell cycle kinetics.

The effects of individual drugs on cell cycle progression can often be determined by analyzing the DNA distribution of cultured cells at appropriate times after drug administration. In addition, to cell counts, RNA and/or protein content, the alterations in cell cycle distribution of drug-treated cells can yield information on the potential cell cycle phase specificity of the drug. However single parameter DNA analysis, as currently used, can give inaccurate information when drug effects are associated with cytokinesis perturbations, in spite of various statistical and mathematical analyses. Scanning flow cytometry could be an interesting alternative for the detection of binucleate cells.

Animals↗
PubMed1985

Flow cytometric analysis of pentakis(aziridino)thiatriazadiphosphorine oxide (SOAz)-induced changes in cell cycle progression of HeLa and HL-60 cells.

The treatment of HeLa and HL-60 cells with various concentrations of pentakis(arizidino)thiatriazadiphosphorine oxide results in inhibition of growth and modification of cell cycle distribution. These phenomena were observed at 10(-4) M and 5 X 10(-5) M for HeLa cells and 10(-5) M and 5 X 10(-6) M for HL-60 cells. The estimation of DNA content by flow cytometry showed an important shift in the distribution of cycling cells with a striking arrest in G2 for both cell lines with a concomitant late S-phase accumulation for HeLa cells. Incubation of cells in drug-free medium 3 days after treatment did not show any change in DNA distribution, suggesting the irreversibility of drug action.

Azirines↗
PubMed1984

Effects of sodium butyrate on growth and cell-cycle kinetics of cultured rabbit articular chondrocytes.

The sodium salt of n-butyric acid was found to inhibit the growth of asynchronous cultures of rabbit articular chondrocytes. This inhibitory effect was dose-dependent between 1 mM and 5 mM, reversible, and accompanied by volume enhancement and modification of cellular morphology. Flow-cytometric analysis showed that drug exposure led to a slowing-down of the cell-cycle progression; after 1 day's exposure, cells accumulated in G1, and after 2 or 3 days' treatment, in G2, without a blockage in M; the increase of cells in G2 was in fact due to an enhancement of binculeated cells. The treated cells had an increased RNA content. Articular chondrocytes seem to be target cells for sodium butyrate and therefore it represents a valuable biological tool for studying the mechanisms of their growth regulation.

Animals↗
PubMed1984

Cell multiplication and type II collagen production by rabbit articular chondrocytes cultivated in a defined medium.

The complexity and the variations in the efficiency of different batches of serum stimulated the preparation of a serum-free medium which could promote not only growth, but also the differentiation properties of rabbit articular chondrocytes in culture. The serum-free medium (SFM) developed in this study contained insulin, transferrin, Na-selenite, human fibronectin bovine serum albumin (BSA), brain growth factor (BGF) or fibroblast growth factor (FGF), hydrocortisone and multiplication stimulating activity (MSA). Primary or secondary cultures of chondrocytes in such a medium attained a proliferation rate equal to 70-80% of that obtained with chondrocytes grown in a serum control medium. The deletion of various factors from SFM indicates that BGF or FGF are the most stimulating of growth factors. Insulin was beneficial when used individually; when combined with BGF or FGF, they had a synergistic effect on cell proliferation. MSA seemed not to play any role in chondrocyte growth in culture. The SFM medium did not modify either the morphology or the progression of cells into the cell cycle. It moreover allowed the maintenance of the specific function of chondrocytes to synthesize type II collagen.

Animals↗
PubMed1984

Culture of chondrocytes in medium supplemented with fetal calf serum or a serum substitute: Ultroser G.

Fetal calf serum and a serum substitute, Ultroser G, were compared for their effects on the growth curves, clonal growth and cell cycle progression of rabbit chondrocytes in primary culture and during at least three cell passages and included a screen for the maintenance of cartilage-like differentiation i.e. the presence of type II collagen. Proliferation was also compared with another serum substitute, Nu-Serum. Ultroser G is shown to be equivalent to fetal calf serum as far as chondrocyte proliferation is concerned, clonal growth is improved and biosynthesis of type II collagen is maintained in primary culture.

Animals↗
PubMed1984

Effects of D-penicillamine on growth and cell cycle kinetics of cultured rabbit articular chondrocytes.

The long-acting antirheumatic drug D-penicillamine was found to inhibit the growth of asynchronous cultures of rabbit articular chondrocytes. This inhibitory effect was dose-related between 5 X 10(-4) M and 5 X 10(-3) M and was time-dependent for a given dose. Flow cytometric analysis showed that drug exposure led to a slowdown in cell cycle progression. This was manifested as a decrease in the number of cells in S phase, due especially to an accumulation of cells in G0 G1 and also to a slight cessation of cell transit through G2 M. Recovery experiments showed that the effect is transitory and reversible. It is suggested that the articular chondrocyte is a target cell for D-penicillamine and that these cells have a D-penicillamine sensitive restriction point in the G0 G1 phase of the cell cycle and to a less extent in the G2 M phase.

Animals↗
PubMed1983

DNA flow cytometric analysis of monogranulocytic colony forming cells from mouse bone marrow in vitro.

An adaptation of a previously reported flow cytometric technique is described. This technique was applied to study the DNA distribution of mouse granulocyte-macrophage colony forming cells (GM-CFc) grown in a methyl cellulose culture system. This method involved the collection of cell clusters and colonies from the methyl cellulose culture medium for the subsequent determination of DNA content. The DNA content of the homogeneous GM-CFc suspensions was determined by applying a modification of the propidium iodide staining procedure described by Crissman et al. The relative percentage of cells in G0 + G1, S, and G2 + M stages of the cell cycle was calculated by applying mathematical analysis to the resulting DNA histograms. This method could be useful in studying the effects of drugs on GM-CFc kinetics.

Animals↗
PubMed1983

Effects of donor's age on growth kinetics of rabbit articular chondrocytes in culture.

The in vitro proliferative capacity of articular chondrocytes derived from young and old rabbits was investigated to examine if the modifications incurred can be related to the in vivo aging. Determinations were made of the cartilage cell density, cell volume, cell number at confluency, plating efficiency, growth curve and DNA content distributions. The old donor cells were characterized by a decline in all the parameters of cartilage growth studied: cell number at confluency, cell replication rate (from 20 h to 45 h) as well as an increase in cell volume. The mean cycle time in vitro increased from 17.5 h compared to 27 h during in vivo aging, essentially because of an elongation of the G1 phase. Chondrocytes derived from young and old donors may be an appropriate model system for studying the in vitro effects of drugs on rheumatoid diseases as a function of in vivo aging.

Aging↗
PubMed1983

Proliferation kinetics of rabbit articular chondrocytes in primary culture and at the first passage.

The in-vitro proliferation kinetics of young rabbit articular chondrocytes were compared in primary culture and at the first passage. The growth curves labelling and mitotic indices, percentage labelled mitosis (PLM) curves and DNA content distributions by flow-microfluorometric analysis during a 7-day growth period were determined in both cases. The length of the cell cycle and the doubling time calculated from the exponential part of the growth curve were quite similar: Tc = 19 hr and Td = 20 hr for the primary culture, Tc = 17 X 3 hr and Td = 20 hr for the first passage. However, the growth curve and the DNA distribution during the 7-day period showed some differences. The duration of the lag period studied by the growth curve was longer in the primary culture than at the first passage. This phenomenon was also observed using the FCM analysis. The growth fraction determination on the second day of culture was in accordance with the lower proliferation capacity of the cells in primary culture. These data suggest that it would be better to study growth kinetics and drug modifications in articular chondrocytes at the first passage than in primary culture.

Animals↗
PubMed1982

Effect of sodium cis-beta-4-methoxybenzoyl-beta-bromacrylate (Cytembena) on HeLa cell kinetics.

The treatment of HeLa cells with various concentrations of sodium beta-4-methoxybenzoyl-beta-bromacrylate (Cytembena) results in inhibition of growth and modification of cell cycle distribution. These phenomena were observed at concentrations between 7.5 x 10(-5) and 2.5 x 10(-5) M. The estimation of DNA content by flow cytometry showed an important shift in the distribution of cycling cells with a relative decrease of G0 + G1 cells and a striking accumulation of G2 + M cells. According to our experimental conditions, the blocking up in G2 + M is irreversible at 7.5 and 5 x 10(-5) M.

Acrylates↗
PubMed1980

[Inhibitory effect of cytembena (sodium-cis-beta-methoxybenzoyl-beta-bromoacrylate) on the cell kinetics of HeLa cells in culture].

The inhibiting effect of Cytembena on HeLa cell kinetics has been demonstrated and analyzed. The percentage of cycling cells decreases, according to the concentration, between 7.5 and 2.5 x 10(-5) M. Estimation of DNA by cell flow cytophotometry shows an important shift in the distribution of cycling cells with a relative decrease of G1 cells and a very important accumulation of G2 cells. According to our experimental conditions, the blocking up in G2 is irreversible only at 7.5 x 10(-5) M.

Acrylates↗
PubMed1977

[Modification of chromatin condensation in cultured macrophages during induction of cell division by an inflammatory exudate].

The determination of chromatin condensation in rat peritoneal macrophages in culture showed a predominance of heterochromatin with low transcriptory activity. After induction of division in rat peritoneal macrophages in culture by an acute inflammatory exudate, a decrease of heterochromatin and an increase of euchromatin were observed. This result brings further evidence to support previous observations according to which this type of exudate shows mitogenic properties.

Animals↗