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Biomedical subjects

R M Rosenbaum

Publications and source records attributed to R M Rosenbaum.

8 recordsLinked to original sources
PubMed1978

The type 1 alveolar lining cells of the mammalian lung. II. In vitro identification via the cell surface and ultrastructure of isolated cells from adult rabbit lung.

Using a newly described dissociation and isolation technique, Type 1 alveolar lining cells were obtained from adult rabbit lung within a heterogeneous population. Identification of many lung cell types in this mixed population was by a) comparison of isolated cells with in situ lung cells in lung sections using identical parallel staining, b) stepwise ultrastructural examination of cells during all stages of lung dissociation so that intercellular associations were monitored throughout, and c) Type 1 cell surface changes following collagenase treatment. This phenomenon was studied with both electron and light microscopy, the latter employing tetrachrome staining of basophilic blebs as well as characteristic staining of nucleus and cytoplasm. Following their isolation, most Type 1 cells lost their surface blebs and assumed a "relaxed" state. In this condition, Type 1 cells were exposed to cytochalasin D (CD) for various times and at several concentrations. Surface knobs, having all the characteristics of zeiotic knobs produced in a number of cultured cell lines by exposure to CD, were produced in isolated Type 1 epithelial cells within 45 minutes. The reaction to CD was temperature-dependent, proceeding maximally at 37 C with inhibition at lower temperatures and was inhibited by antimetabolites such as dinitrophenol and 2-deoxyglucose in the presence of CD. As with established cell lines, formation of zeiotic knobs at the isolated Type 1 cell surface appeared closely related to microfilamentous nets located beneath the plasmalemma. The density of this net appeared to vary as isolated Type 1 cells underwent expansion and contraction in response to CD. Zeiotic knobs were formed as the result of herniation of endoplasm through the cell cortex. The significance of such a labile cortical zone is considered in relation to the deformation changes Type 1 cells undergo during inflation-deflation of alveoli and the folding-unfolding of alveolar lining cells as a result of lung volume changes.

Animals↗
PubMed1978

The type 1 alveolar lining cells of the mammalian lung. I. Isolation and enrichment from dissociated adult rabbit lung.

With removal of large numbers of macrophages by airway lavage, Type 1 cells were isolated in heterogeneous cell populations following the stepwise dissociation of lung tissue. Using a carefully timed collagenase-trypsin digestive sequence at 37 C, unwanted cellular and noncellular lung components were minimized prior to selective release of Type 1 cells. Resulting heterogeneous cell suspensions containing well-preserved Type 1 cells, as determined by electron microscopy, were layered onto a shallow gradient (3 to 6% Ficoll in minimal essential medium [MEM]) and separated at unit gravity into enriched subpopulations of various cell types. These included various fractions enriched with respect to Type 1 cells (70%), Type 2 cells (82%), and macrophages (81%). Identification of Type 1 cells following their isolation and gradient enrichment was established by light microscopic staining techniques and by specific cell surface characteristics in vitro as visualized by electron microscopy.

Animals↗
PubMed1977

Ultrastructure of in vitro type 2 epithelial cell cysts derived from adult rabbit lung cells.

Fragments of adult rabbit lung, composed chiefly of terminal airway obtained by a trypsin digestion technique were maintained on collagen-coated cellulose sponges in Ham's F12 medium. Cell-sponge associations were examined with light microscopy, scanning and transmission electron microscopy over a period from 6 to 28 days. After an initial 24- to 48-hour period of cell migration from the airway fragment, sponge matrices became lined with cells suggestive of alveolar macrophages. After one week in culture, cysts appeared to be composed entirely of type 2 epithelial cells. These were characterized by a microvillous apical border and an elaborate junctional complex. The lumen of these cysts contained both myelin-like lamellar configurations and tubular myelin structures such as have been described from pulmonary washings. Consistent with the age of the sponge cultures, one or more cyst types described as young, middle and late could be found simultaneously. Middle aged cysts showed signs of active secretion into the lumen. Late cysts showed changes in the epithelium comprising the cyst wall suggestive of a cell type intermediate between type 1 and type 2 epithelial cells.

Animals↗
PubMed1977

Effects of prostaglandins E2 and F2alpha on lecithin biosynthesis by cultured lung cells.

Transformed cells from human lung carcinoma (Line A549), resembling type II pneumocytes, were cultured in monolayer at 37 degrees C and incubated for five hours with 3H-choline and 14C-palmitate in the presence of various concentrations of prostaglandins (PGS) E2 and F2alpha. In the control (no PG) the level of % palmitate incorporation was 13.5 x as high as that of choline, after taking isotope dilution into account. Between the concentrations studied, 0.1 and 10 muM, both prostaglandins stimulated markedly the incorporation of both precursors, though choline up to 3 x better than palmitate. This was indicated by a change in the palmitate/choline incorporation ratio from 13.5 to as low as 4.2. At the lowest PG concentration, 0.1 muM, PGE2 was much more effective than PGF2alpha in stimulating the incorporation of both precursors.

Cell Line↗
PubMed1976

Culture characteristics of cells derived from type II pneumocyte enriched fractions from rabbit and rat.

Type II cell enriched fractions were isolated from rabbit and rat lungs using density gradient centrifugation. Cultures established from these fractions contained predominantly cells similar in most morphological respects to type II pneumocytes. These were in continuous replicating culture for 1 year and still exhibited contact inhibition. Membrane-bound structures reminiscent of, but no longer strictly identical to, type II cell lamellar cytosomes were seen in cells from these long-term cultures although their numbers were reduced in comparison to lamellar bodies in freshly isolated cells. Mitochondrial numbers and sizes, determined morphometrically, were reduced after culture in comparison to freshly isolated type II cells and those in situ. Phosphatidylcholine was synthesized by these cells and released into the extracellular medium. Application of laser activated electronic sizing data, confirmed by direct micrometry, demonstrated a significant increase in cell size as a function of culture. This sizing data, after prior confirmation by electron microscopy, was used as an aid in identifying type II cells and macrophages in dispersion, especially with those cells derived from rabbit lungs.

Animals↗
PubMedDate not supplied

Cultured lung cells: interplay effects of beta-mimetics, prostaglandins and corticosteroids in the biosynthesis of dipalmitoyl lecithin.

Cell lines derived from type II lung cells were used to study interplays of substances affecting incorporation of labeled precursors [1(-14)C]palmitate and [methyl-3H]choline into phosphatidyl choline. Ethanol stimulated markedly biosynthesis of dipalmitoyl phosphatidyl choline in cloned rabbit lung cells; the stimulating action of ethanol was reduced very much by cortisol and less by ritodrine. In the presence of 0.1 microM isoproterenol, two prostaglandins, E2 and F2alpha, caused marked depressions in the incorporation of both precursors by cell line A 549 derived from human lung adenocarcinoma. One concluded that among the agents studied, ethanol and cortisol are potent antagonists, and so were also the prostaglandins and isoproterenol.

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