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R M Zucker

Publications and source records attributed to R M Zucker.

77 records · Page 5Linked to original sources
PubMedDate not supplied

Fixation of the plasma membrane/cytoplasm complex: a mechanism of toxic interaction of tributyltin with the cell.

Flow cytometric and light/fluorescence microscopic analysis of murine erythroleukemic cells (MELC) and electron microscopic investigation of porcine microsomal membrane preparations suggest that tributyltin (TBT) toxicity is mediated through fixation processes (protein denaturation, crosslinking, and so on) within the plasma membrane/cytoplasm complex. This hypothesis was derived from the following observations: 1. Exposure of the MELC to micromolar concentrations of TBT results in increased resistance to detergent-mediated cytolysis; 2. Exposure of porcine renal microsomal membrane preparations to similar concentrations results in inhibition of vanadate-mediated crystallization of Na+,K(+)-ATPase, a process requiring protein mobility within the membrane; 3. Flow cytometric and fluorescence microscopic analyses indicate that MELC exposed to submicromolar concentrations of TBT exhibit increased cellular carboxyfluorescein retention; and 4. Nuclei prepared from TBT-treated cells by detergent-mediated cytolysis exhibit increased axial light loss, 90 degrees light scatter, fluorescein isothiocyanate fluorescence, and the presence of adherent proteinaceous tags. The DNA distribution histogram of such nuclei also is perturbed.

Animals↗
PubMedDate not supplied

Limitations of the fluorescent probe viability assay.

In vitro assessment of the efficacy/capacity of toxicants (e.g., cancer chemotherapeutic agents, environmental pollutants, etc.) to damage/kill cells and/or inhibit growth (cell duplication) requires accurate measurement of target cell viability as a function of exposure. Rapid measurement of viability, such as can be achieved employing fluorescent probes of metabolic function in combination with instrumental analysis, is highly desirable. However, we observe that exposure to chemicals (of unrelated type) complicates the interpretation of viability data and, in the case of perturbed cells, questions the validity of viability growth assays based on intrinsic enzyme activity. Viability commonly is determined flow cytometrically (FCM) by the carboxyfluorescein diacetate (CFDA)/propidium iodide (PI) assay. Nonfluorescent CFDA is taken up by diffusion and converted via cytoplasmic esterase-catalyzed hydrolysis to carboxyfluorescein (CF), a negatively charged fluorescent molecule that is retained (incompletely) by the cell. As such, if CF fluorescence intensity is a relative measure of enzyme activity, it also can be considered an index of cellular vigor (metabolic rate). It is generally accepted that the viable cell excludes both basic dyes, such as PI, and acidic dyes, such as trypan blue, and uptake is indicative of irreversible cellular injury presaging cell death. We observe that, following incubation for 4 h with 0.5-1.0 microM tributyltin (TBT), a potent environmental toxicant, murine erythroleukemic cells (MELC) exhibit enhanced (supranormal) CF fluorescence compared to control cells. Apparent cell volume (ACV) is unaltered, and because such cells exclude PI, they are considered viable in terms of the CFDA/PI assay. However, rate of growth (increase in cell number over 48 h) is depressed, suggesting that supranormal CF fluorescence, even in the absence of PI uptake, is indicative of cellular perturbation. In effect, although CF fluorescence is the product of an enzyme-catalyzed reaction and, therefore, an indicator of vital function (enzyme activity), it apparently is not a reliable index of cellular vigor. At higher TBT concentrations (greater than 1.0, but less than 50.0 microM), the cells exhibit both increased CF fluorescence and PI fluorescence and are growth inhibited. MELC exposed to the cancer chemotherapeutic agents adriamycin, m-AMSA, or crisnatol (Burroughs Wellcome 770U82) also exhibit increased cellular CF fluorescence. However, rate of growth is decreased and ACV increased. The latter, measured either as a function of electrical resistance (Coulter volume) or by the FCM parameter axial light loss could account for the increase in mean CF fluorescence.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

Centrifugal Cytology, IV. The Prearation of fixed stained dispersions of gynecological cells.

The Centrifugal Cytology technique has been utilized to produce glutaraldehyde fixed stained dispersions of both conventional Ayre scrapes and Davis pipet (PAPette) samples. Light microscope studies of dispersions of both types of cells on conventional microscope slides indicated that both the tinctorial and morphological appearance of the cells after Papanicolaou staining was very similar to that observed with conventional smears and that the same criteria could be utilized with the Centrifugal Cytology dispersions to screen the cells for cancer as had previously been used with the smears. A preliminary study indicated that six out of six positives with no false negatives or false positives were found. The Centrifugal Cytology technique appears to have promise as a method for preparing suspension samples such as pipets of gynecologic cells. Scanning electron microscope studies reveal that the squamous epithelial cells are very thin and at least some of them are covered by a network structure.

Carcinoma, Squamous Cell↗