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Biomedical subjects

A D Deitch

Publications and source records attributed to A D Deitch.

50 records · Page 3Linked to original sources
PubMed1983

Limitations of DNA histogram analysis by flow cytometry as a method of predicting chemosensitivity in a rat renal cancer model.

Analysis of DNA histograms obtained from rat renal cancer cells stained with propidium iodide and submitted to flow cytometry revealed a tumor cell population with prominent 2C and 4C peaks and with usually less than 10% each of S-phase or hyper-4C cells. The presence of an increased proportion of 4C cells was found to depend on the age and size of the tumor nodule. Sampling replicate portions of the same tumor or different tumors of the same size and age frequently revealed highly variable 4C:2C ratios. Treatment of animals bearing this tumor with a single i.p. injection of cyclophosphamide (CY), under conditions known to reduce the tumor burden by 80% within 1 week, or with 5-fluorouracil (FUra), which is ineffective against this tumor, in many cases did not yield changes in DNA histograms that permitted one to distinguish the effective drug. Either no marked difference in histogram shape occurred after therapy, or FUra induced more striking differences in cell cycle position than did CY. In tumor generations with greater than 15% S-phase cells, treatment with CY resulted in multiple effects on DNA histograms. These included detecting increased numbers of moribund cells (hypo-2C), a decrease in 4C cells, and an increase in hyper-4C cells. These changes did not occur with the ineffective agent FUra. The tumors grown in vitro show no evidence of replication of 4C cells. The DNA histograms of late-log-phase cultures have a major 2C peak and a minor S plus G2 hump. Since neither the untreated tumor in vivo nor that grown in vitro has a major hyper-4C cell population, it is probable that the tumor stem cells are chiefly 2C (diploid-hyperdiploid). Treatment in vitro of late-log-phase cultures with CY or FUra produces DNA histograms which permit identification of the effective agent. After CY, a major part of the cell population was hypo-2C (moribund) cells.

Animals↗
PubMed1982

A stable propidium iodide staining procedure for flow cytometry.

A propidium iodide (PI) staining procedure is described in which 50 micrograms/ml PI in 10(-2) M Tris, pH 7.0, with 5 mM MgCl2 is used to stain murine erythroleukemia cells (MELC) grown in suspension culture as well as single cell suspensions derived from rat kidney adenocarcinoma and human prostatic carcinoma. Specificity of staining of nuclear DNA is achieved by enzymatic removal of RNA using RNAse in the staining solution. Virtually identical histograms, with the same G1 peak height and closely similar coefficients of variation (CVs), are obtained using a wide range of RNAse concentrations on replicate samples of MELC if the incubation times are sufficiently prolonged when employing the lower enzyme concentrations. For 1 mg/ml RNAse on logarithmically growing MELC, 30 min incubation at 37 degrees C is needed to obtain a maximum G1 peak height and optimal CV and there is no significant change in the histogram if the incubation is prolonged to 4 hr. For every 4-fold decrease in RNAse concentration, the incubation time at 37 degrees C must be doubled to obtain the same maximal G1 peak height and optimal CV. Unfixed cell preparations, whether derived from suspension or monolayer cultures or from solid tumors, are stable for 2 or more weeks if stored at 4 degrees C between flow cytometric analyses and histograms are usually only minimally altered if the stained cell samples are stored for 1-2 months at 4 degrees C. Sample decay is associated with bacterial contamination. If sterile preparative techniques are used initially, subsequent contamination of the stained preparations may be minimized by adding sodium azide to the stained samples at 0.1% without influencing fluorescence intensity. Glycerine may be added to 10% and the samples slowly frozen for storage without altering DNA histogram shapes. The simplicity of sample preparation and the stability of the resulting stained cell samples makes this procedure suitable for repetitive comparative sampling of tissue and cell populations over prolonged time spans.

Animals↗
PubMed1975

Action of cytochalasin D on cells of established lines. III. Zeiosis and movements at the cell surface.

The projection of knobby protuberances at the cell surface (zeiosis) is a general cellular response to cytochalasin D (CD), resulting from herniation of endoplasm through undefended places of the cortex during cell contractions and displacement of microfilaments induced by CD. Zeiosis is prevented by agents that interfere with the contractile response to CD, such as inhibitors of energy metabolism or cyclic AMP. The developed protrusions, which remain relatively stable in the presence of CD, contain chiefly mono- or subribosomes, and occasionally other organelles normally resident in endoplasm; compact microfilament felt occupies their bases and extends into their proximal stalks. Protein synthesis in the knobs is less than half of that in the polyribosome-containing endoplasm residual in the main body of the cell. Knobs first protrude singly near the margin of the contracting cells and rapidly cluster into small groups in the periphery even at lower temperature. The clusters then migrate centripetally and coalesce into a large aggregate near the apex of the immobilized and retracted cell: this movement is energy- and temperature-dependent. Aggregation is more prominent and stable in cell lines of epithelial derivation than in fibroblastic or other lines in which nuclear extrusion occurs more readily. The latter is regarded as a special manifestation of zeiosis. Macromarkers, such as latex spherules, migrate like the zeiotic knobs on the cell surfaces in the presence of CD. The aggregated knobs, although persistent for days in the presence of CD, are rapidly recessed after withdrawal of the agent as ruffling is resumed and the cells spread. These movements are discussed in terms of current concepts of mobility of the cell membrane.

Amino Acids↗
PubMed1974

Action of cytochalasin D on cells of established lines. I. Early events.

HeLa, Vero, L, HEp2, and MDBK cells respond immediately to 0.2-0.5 microg/ml cytochalasin D (CD) with sustained contraction (contracture), loss of microvilli, expression of endoplasmic contents (zeiosis), nuclear protrusion, and extension of cytoplasmic processes. The development of these changes is depicted, and the dose-response patterns in these cell lines are described. MDBK is generally most resistant and HeLa most sensitive to these effects of CD. Cells in G(1) are most sensitive to CD; responsiveness decreases progressively during early S and is least in mid S through G(2). CD inhibits transport of [(14)C]deoxyglucose in HeLa by about 45% but has no significant effect on hexose uptake in Vero and MDBK; sugar transport is thus apparently unrelated to any morphologic effect of CD. Although spreading and attachment are impeded, CD does not decrease and may even enhance the adhesiveness of established monolayers. Contraction appears to be a primary early effect of CD, upon which other visible changes follow. It is prevented by some inhibitors of energy metabolism (deoxyglucose and dinitrophenol) and does not occur in glycerinated models without ATP. The possible bases of the contractile response to CD are discussed. Although direct or indirect action of CD on some microfilaments may occur, a generalized structural disruption of contractile filaments by CD is considered unlikely.

Animals↗
PubMedDate not supplied

False DNA aneuploidy in canine and human neoplasms.

In most cases, the appearance of aneuploid peaks in DNA histograms may be an artefact of tissue preparation or it may reflect non-stoichiometric dye binding of a cellular subpopulation rather than true DNA aneuploidy. This report reviews how false DNA aneuploidy can be recognized and eliminated from sample submitted for DNA flow cytometric analysis.

Aneuploidy↗