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D Grunwald

Publications and source records attributed to D Grunwald.

At least 37 records · Page 2Linked to original sources
PubMed1991

Modulation of B2 containing small RNAs during induced differentiation of murine erythroleukemia cells.

We identified a B2 repetitive element approximately 1.9kb down stream from mouse p53 coding gene. This element was then used as a probe to investigate the expression of B2 containing RNA during the induced differentiation of murine erythroleukemia (MEL) cells. This probe revealed two nuclear and one cytoplasmic RNA species. Nuclear small RNAs had a biphasic variation: a decrease followed by a reaccumulation. The cytoplasmic species was essentially non polysomal, and disappeared after the induced differentiation. The presented results suggest that the regulation of these RNAs is associated to cell proliferation and differentiation respectively.

Animals↗
PubMed1991

Cell cycle-related accumulation of H1(0) mRNA: induction in murine erythroleukemia cells.

H1(0), a member of histone H1 family, is associated with cell differentiation in vivo and in vitro. Unlike other histones its synthesis is known to be constitutive during the cell cycle. The present paper provides evidence showing that, in murine erythroleukemia (MEL) cells, H1(0) mRNA accumulation is coupled to DNA replication, but this mRNA is stable enough to remain present all over the cell cycle. Moreover the experiments suggest that H1(0) mRNA accumulates in mid or late S phase rather than when cells initiate DNA replication as does H3 mRNA. H1(0) gene transcription is drastically induced by chemical inducers of differentiation in this cell line. In an attempt to better understand the mechanism of this process, we have studied the inducibility of this gene with respect to the position of the cells in the cell cycle. The experiments show that the most efficient accumulation of H1(0) is observed when cells are treated by the inducer during the S phase of the cell cycle. In the same conditions, H3 mRNA accumulation remains unaffected. These results show that H1(0) mRNA, like H3 mRNA, accumulates during DNA replication, although at a different stage in this phase. The two genes differ, however, in their response to the inducer, suggesting that different regulatory elements might be involved in such a response.

Acetamides↗
PubMed1990

Analysis of the membrane potential of rat- and mouse-liver mitochondria by flow cytometry and possible applications.

Washed and purified rat- or mouse-liver mitochondria exhibiting high membrane integrity and metabolic activity were studied by flow cytometry. The electrophoretic accumulation/redistribution of cationic lipophilic probes, rhodamine 123, safranine O and a cyanine derivative, 3,3'-dihexyloxadicarbocyanine iodide, during the energization process was studied and was consistent with the generation of a negative internal membrane potential. An exception to this was nonylacridine orange which spontaneously bound to the mitochondrial membrane by hydrophobic interactions via its hydrocarbon chain. Energized purified mitochondria stained with potentiometric dyes exhibited both higher fluorescence and population homogeneity than the non-energized or deenergized (nigericin plus valinomycin) mitochondria. By contrast, under non-energized or deenergized conditions, the mitochondrial population exhibited fluorescence intensity heterogeneity related to the residual membrane potential; two subpopulations were evident, one of low fluorescence which may be related to the autofluorescence of the mitochondria (plus non-specific dye binding) and a second population which exhibited high fluorescence. Flow cytometry of the unpurified, simply washed, rat-liver mitochondria stained with rhodamine 123, a classically used dye, provided evidence of their heterogeneity in terms of light-scattering properties and membrane-potential-related fluorescence. One third of the washed mitochondria were found to be non-functional by such assays. The fluorescence of purified rat-liver mitochondria due to the membrane potential built up by endogenous substrates indicates heterogeneity of the mitochondrial population with respect to levels of endogenous substrates. The low-angle light scattering increases upon energization and provides some original information about the shape and modification of the inner mitochondrial conformation accompanying the energization. The heterogeneity of the rat liver mitochondrial population, from a structural, metabolic (existence of endogenous substrates) and functional (active and non-active mitochondrial population dispersion) point of view could thus be demonstrated by flow-cytometry analysis. Two animal models were examined with regard to the alteration of the mitochondrial membrane potential under the effects of drugs (rat-liver mitochondria), and the effects of ammonium toxicity (mouse-liver mitochondria). These results are promising and open new perspectives in the study of mitochondriopathies.

Ammonia↗
PubMed1990

Recovery of RNA from flow-sorted fixed cells.

We describe a method for the preparation of RNA from ethanol-fixed cells, allowing analysis of the RNA from cells "frozen" in a given physiological state. This technique may have important applications in experiments which require prolonged cell manipulations before RNA preparation, such as investigations of cell-cycle-regulated gene expression, which require the preparation of cells for cell-cycle flow analysis, and even for long-term cell sorting. It eliminates all the inconveniences associated with the use of fresh cells, and allows cell-cycle biologists to couple flow cytometry methodology with the advancing techniques of molecular biology.

Animals↗
PubMed1989

Cell subpopulations within proliferative and differentiating compartments of epidermis.

The heterogeneous population of newborn rat keratinocytes was separated into different subgroups according to their cell size. The relation between cell size, position in the cell cycle, RNA content, and proliferative potential in culture was examined. A reserve stem cell population of Go/G1 cells, low in RNA, giving rise to colonies of undifferentiated phenotype in cell culture, has been separated from more differentiated transit basal cells. In the fractions of the larger cells, several subgroups, probably corresponding to different stages of differentiation, were identified: G2M cells with low RNA content, large S-phase cells rich in RNA, and small Go/G1 cells low in RNA. The clonogenic cells from these fractions have limited growth potential and give rise to moderately or terminally differentiated colonies. The selective sorting of stem cell populations may be useful for elucidating the mechanism of carcinogenesis in epidermis and other proliferative tissues. Analysis of the relative proportions of cell subpopulations represents a novel approach leading to the refinement of the concepts of epidermal structure in physiological and pathological states. It also could, by extension, shed new light on the behavior of other proliferative tissues.

Animals↗
PubMed1988

Loss of alleles on chromosome 18 and on the short arm of chromosome 17 in polyploid colorectal carcinomas.

The zygosity of 19 colorectal carcinomas (either near-diploid or polyploid) from patients known to be heterozygous for RFLPs located on chromosome 18 or on the short arm of chromosome 17 has been examined. In most cases, at least one allele was significantly under-represented. The reason for the absence of complete loss of heterozygosity was investigated for 5 polyploid tumors. It was shown that the diploid component which, in these tumors, is essentially composed of non-neoplastic cells, remains heterozygous as the polyploid component invariably loses heterozygosity. The results strongly suggest that many colorectal carcinomas originate from a single cell which had lost at least part of either chromosome 18 or of one short arm of chromosome 17, or both.

Adult↗
PubMed1988

Fluorescence response and sensitivity determination for ATC 3000 flow cytometer.

The fluorescence emitted by labeled particles after interaction with exciting light is conditioned by laser beam geometry and by the mode of fluorescence collection and filtration. A laser elliptic focusing mode is described, and the fluorescence characteristics of the sample cell flow are calculated. Fluorescence collection and detection through optical filters were analyzed, and efficiency was calculated for the ATC 3000 flow cytometer (Odam-Bruker, Wissembourg, France). A mathematical model is proposed for calculation of the fluorescence signal and its fluctuations. The background noise for the ATC 3000 was quantified experimentally using fluorescent microspheres of a known number of bound equivalent fluorescein isothiocyanate (FITC) molecules. These experimental measurements were found to fit the theoretical predictions, thus validating the proposed model.

Evaluation Studies as Topic↗
PubMed1988

Recurrent t(11;22) breakpoint mapping by chromosome flow sorting and spot-blot hybridization.

The breakpoint of the recurrent t(11;22) translocation, one of the most frequent chromosome anomalies encountered in human population, always involves bands 11q23.2 and 22q11.2. The involvement of the C lambda locus of the immunoglobulin lambda gene cluster on chromosome 22 has been suggested: however, in situ hybridization experiments have yielded conflicting results. In order to solve these discrepancies by another approach, we have used bivariate flow sorting to separate the chromosomes of interest and to map the specific breakpoints by direct spot-blot hybridization with the gene-specific radiolabelled DNA probes, Alu, V lambda, ets. The results showed unambiguously that in the t(11;22) patient analysed, a set of C lambda and V lambda genes was translocated to the der(11) chromosome. Since V lambda genes are situated proximally to C lambda genes, we demonstrate that, in the case studied here, the chromosome 22 breakpoint is not located within or even immediately close to the C lambda region.

Cell Line↗
PubMed1988

Time dependence of chromosomal aberrations induced in human and monkey lymphocytes by acute and fractionated exposure to 60Co.

Changes in the numbers of peripheral lymphocytes with chromosome aberrations were observed in cynomolgus monkeys after fractionated or acute 60Co irradiation at the same total doses. Immediately after irradiation, the yield of dicentrics decreased when the dose was fractionated but remained constant for 20 to 80 days, depending on the dose, when irradiation was acute. Lymphopenia was greater than expected when the dose was fractionated. The kinetics of the loss of chromosome aberrations and the changes in peripheral lymphocyte count occurring in monkeys after acute irradiation were compared to those observed in accidentally irradiated men.

Animals↗
PubMed1986

Swine chromosomes: flow sorting and spot blot hybridization.

Flow cytometry analysis was applied to swine chromosomes prepared from phytohemagglutinin (PHA) stimulated peripheral blood lymphocytes. Flow karyotypes from both sexes and from t(3;7) translocation carrier females were obtained. A certain number of chromosome pairs could be assigned to various peaks. In fact, 13 peaks were observed for 18 autosomal pairs plus X and Y. Moreover, abnormalities owing to the t(3;7) translocation were readily observable. The number of base pairs for chromosomes associated with the various peaks was estimated by comparison with human flow karyotypes. The following four peaks were thus sorted: the peak assumed to represent the translocated chromosome 7 plus the normals associated with it; the corresponding peak from a normal swine; the peak assumed to contain among others the normal chromosome 7; and finally the peak corresponding to swine chromosome 1. Chromosomes of each peak were collected on Pall Biodyne membrane. Following appropriate denaturation and prehybridization, the four samples were hybridized with a human leucocyte antigen (HLA) class I 32P-labelled cDNA probe, representing most of the coding sequence of the HLA B7 gene. The results confirmed previous data from other techniques that assigned the swine MHC(SLA) to chromosome 7. Subsequently, sorted samples were hybridized with a porcine genomic Interferon alpha probe in order to confirm the mapping of this gene family on porcine chromosome 1.

Animals↗
PubMed1983

[Analysis of human chromosomes by the flow microcytometer].

Human peripheral lymphocytes metaphase chromosomes, prepared for flow analysis were used to evaluate the resolving power of a new microscope-based flow cytometer "Leitz MPV flow". We were able to resolve the human karyotype into about 15 peaks after simple ethidium bromide staining and excitation with mercury arc lamp. These results showed that a simple flow cytometer with a common relatively inexpensive source of fluorescence excitation light, can compete with more sophisticated laser-illuminated flow cytometers for flow cytogenetic studies.

Cells, Cultured↗
PubMed1975

[Coronary emboli in mitral stenosis].

Study of four personal cases and of twelve cases reported in the literature makes it possible to describe the characteristics of coronary embolism in mitral stenosis, a rare complication but indicating the presence of a left intra-atrial thrombosis: -- variable clinical picture, dominated by a syndrome combining simultaneously a picture of myocardial infarction and of peripheral arterial emboli of other localizations; -- diagnosis to be discussed within the framework of coronary syndromes in mitral heart disease: embolism requiring to be distinguished from coronary atherosclerosis combined with mitral stenosis, more rarely a functional coronary insufficiency; -- severe course and prognosis: besides the possibility of rapidly lethal cases, coronary embolism seems liable to result in weakening and diminishing of the adaptation possibilities of the left ventricle, responsible for attacks of heart failure after mitral valvulotomy.

Adult↗