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Biomedical subjects

M Wittner

Publications and source records attributed to M Wittner.

At least 163 records · Page 9Linked to original sources
PubMed1980

Effect of sodium cyanate on Plasmodium falciparum in vitro.

Sodium cyanate at concentrations as low as 0.5 mM inhibited the growth of Plasmodium falciparum (FCR-3 Strain) utilizing the Trager-Jensen continuous culture system. At concentration higher than 1 mM, the parasites were irreversibly destroyed. Utilizing synchronized cultures, the relative susceptibilities of early and late trophozite forms were examined, and it was found that both developmental forms were equally susceptible to the action of cyanate. Pretreatment of red cells with sodium cyanate prior to infection did not alter the intracellular growth of the parasite. Consequently, the effect of the drug is likely to be on the parasite per se rather than the red cell. The mechanism of action is probably the carbamylation of essential, parasite proteins that eventually impair growth and/or function. Published pharmacological studies in humans would predict that the level of cyanate at which growth inhibition occurs in vitro can be achieved in vivo and that the adverse effects will likely be minimal for short treatment periods.

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↗
PubMed1975

Studies of in vitro infection by Trypanosoma cruzi. I. Ultrastructural studies on the invasion of macrophages and L-cells.

The interactions of Trypanosoma cruzi with L-cells, and with normal and activated macrophages in vitro were studied by ultrastructural techniques. T. cruzi actively invades cultured L-cells and uniformly destroys them. Normal macrophages could control a 1:1 (parasite to host cell) infection, but were destroyed by a 10:1 infection. BCG-activated macrophages, however, controlled a 10:1 infection but not one at a ratio of 100:1. It appears that parasites that survive within host cells do so outside cytoplasmic vacuoles, whereas when they are relegated to host cell phagosomes they are destroyed. Culture forms of T. cruzi have several means of access into host cells. Marcrophages are better able to survive infection than are non-phagocytic cells. Finally, it is suggested that control of an experimental infection in vitro is dependent upon numbers of parasites to macrophages as well as the state of the macrophages.

Animals↗