Electron microscopic study of the cytopathogenic action of meningococci in a continuous human amnion cell culture

The electron-microscopic study of the interaction of meningococci with continuous human amnion cell culture F1 has revealed that this process comprises 3 stages. The study has shown that, following the adhesion of meningococci to the surface of cells F1, these cells are invaded by individual coccal forms of meningococci. In response to infection vacuoles appear in the cytoplasm of the cells. Meningococci are either phagocytosed inside these vacuoles, or their release into the intercellular space and the death of the infected by meningococci are observed. When the cells are infected by cytopathogenic strains, the infectious process results in the appearance of degenerative changes in the cells.     

Characterization of prostaglandin formation by human amnion cells in monolayer culture

In the present investigation, we found that among the prostanoids that human amnion cells, which are maintained in monolayer culture, secrete into the culture medium, prostaglandin E₂ is by far the predominant one. In the presence of inhibitors of prostaglandin synthase, the production of prostaglandin E₂ by these cells is abolished. Amnion cells maintained in the presence of fetal calf serum produce greater quantities of prostaglandin E₂ than do cells maintained in serumless medium. In the amnion cells, there is little or no metabolism of prostaglandin E₂; this also is true of amnion tissue. The unique characteristics of prostaglandin biosynthesis and metabolism by human amnion cells in monolayer culture are identical with those of human amnion tissue. Hence, we suggest that amnion cells in culture constitute an excellent model for investigations of the regulation of prostaglandin E₂ biosynthesis in this tissue.     

Characterization of prostaglandin formation by human amnion cells in monolayer culture

In the present investigation, we found that among the prostanoids that human amnion cells, which are maintained in monolayer culture, secrete into the culture medium, prostaglandin E2 is by far the predominant one. In the presence of inhibitors of prostaglandin synthase, the production of prostaglandin E2 by these cells is abolished. Amnion cells maintained in the presence of fetal calf serum produce greater quantities of prostaglandin E2 than do cells maintained in serumless medium. In the amnion cells, there is little or no metabolism of prostaglandin E2; this also is true of amnion tissue. The unique characteristics of prostaglandin biosynthesis and metabolism by human amnion cells in monolayer culture are identical with those of human amnion tissue. Hence, we suggest that amnion cells in culture constitute an excellent model for investigations of the regulation of prostaglandin E2 biosynthesis in this tissue.     

Use of irradiated human amnion as a matrix for limbal stem cell culture

Several ocular diseases affect the corneal surface; the development of effective technologies for the treatment of corneal lesions has brought about an improvement in the quality of life of affected patients. The aim of this study is to culture and characterize limbal stem cells cultured on gamma (⁶⁰Co) radiosterilized human amnion (RHA). Limbal stem cells were isolated from ten preserved samples of corneal transplant. The cells were cultured since primary culture until expanded cells on RHA and stained with monoclonal antibodies to establish their immunophenotype, after which cytokeratin 12 and Vimentin were positive by immunohistochemistry. The immunophenotype remained constant since primary culture until expanded cells in RHA. The RHA and cells construct were structurally integrated. Immunohistochemistry was cytokeratin 12, Vimentin positive, and cytokeratin 19 negative. In vitro limbal cells maintain a constant epithelial transition immunophenotype in culture up to primary culture until expanded cells on RHA.     

Cellular morphology of human malignant melanoma in primary culture

Summary Early monolayer outgrowths of cells from human cutaneous malignant melanomas mostly derived from metastatic lesions were examined microscopically. Cells resembling the two dendritic types of melanoma previously described in the established lines could readily be recognized. Of 22 specimens, 14 consisted of cells with a triangular dendritic morphology, four had both triangular and elongated dendritic morphology, and one had a cuboidal morphology. The remaining three specimens showed only fibroblastic outgrowths. It is concluded that cells with a triangular dendritic morphology are either the most common type of the secondary cutaneous melanomas, or alternately the most adaptable to the present culture conditions. An association of a more favorable prognosis with the homogeneous triangular dendritic cell type is noted. This study was supported in part by grants from The Medical Research Council of Canada and The Ontario Cancer Treatment and Research Foundation.     

Cellular reporoduction and extracellular polymer formation by Pseudomonas aeruginosa in continuous culture

The kinetics of cellular reproduction and the rate and extent of synthesis of extracellular polymeric substances (EPS) were investigated for P. aeruginosa growing in glucose-limited chemostats. mu(max) and K(s) estimates of 0.4 h(-1) and 2 mg glucose C/L, respectively, at 25 degrees C were obtained for this bacterium. The extent of EPS formation was inversely related to the growth rate of P. aeruginosa. The rate of EPS formation had both growth- and non-growth-associated components. The growth-associated polymer formation rate coefficient (k) was 0.3 mg polymer C/mg cellular C and the non-growth-associated polymer formation rate coefficient (k') was 0.04 mg polymer C/mg cellular C/h. The values for k and k' must be regarded as provisional since the product formation data were quite variable at low dilution rates. Estimates of the cellular (Y(x/s)) and polymer (Y(p/s)) yield coefficients were 0.3 mg cellular C/mg glucose C and 0.6 mg polymer C/mg glucose C, respectively. Most of the non-growth-associated consumption of glucose detected was due to exopolymer formation.     

The effects of p-DL-fluorophenylalanine on chromosome movement and cytokinesis of human amnion cells in culture

An analysis is presented of time lapse motion picture films showing the effects of DL-p-fluorophenylalanine (PFPA) on chromosome movement in cultured human amnion cells. The data indicate that PFPA has the unusual effect of slowing the rate at which chromosomes move in anaphases which occur after the beginning of treatment. Irrespective of treatment, cytokinesis begins when chromsome movement has progressed to a relatively fixed point. Thus, a slowdown in the rate of chromosome movement leads to a delay in initiation of cytokinesis. Cytokinesis, once it begins, is not affected by treatment with the analog.     

Effect of gamma-irradiation on lipid content and survival of human amnion cells in culture.

The neutral lipid content of Human Amnion cells in tissue culture, studied by cytophotometry, increases after irradiation with 60Co gamma-rays. Cells having an already elevated lipid content, induced by lipid pretreatments, become sensitized to irradiation as determined by cell survival and electrophoretic mobility studies.     

Effect of cholera toxin on the ultrastructure of a primary culture of human fetal intestinal epithelium

Ultrastructure of the primary culture of epitheliocytes in the small and large intestine of 20-22-week-old human fetuses has been investigated, normal and 1, 3, 6, 12 and 24 h after administration of cholera toxin (choleragen) into the cell culture. The culture studied is mainly presented by absorbtive epitheliocytes, goblet, endocrinic and Paneth's cells, that preserve to a certain degree their differented structure. The most pronounced ultrastructural changes of the intestinal epitheliocytes in the primary cell culture, resembling those, that are previously noted in the epitheliocytes of the small and large intestine under influence of cholera toxin in various experimental animals in vivo, are revealed 3-6 h after administration of cholera toxin into the primary culture of the small intestine epitheliocytes and 6-12 h--into the large intestine epitheliocytes. The intestinal epitheliocytes of the human fetuses in the cell culture are sensitive to the action of cholera toxin and present a suitable model for studying the action mechanism of the toxin on the intestinal epithelium.     

Cellular inequivalence in a culture of Schizosaccharomyces pombe

The fission yeast Schizosaccharomyces pombe was grown in the chemostat at D = 0.03, 0.05, 0.1, 0.15 and 0.20 h-1. The dry weight and substrate quantities, the number of cells and their morphological characteristics were determined in the steady state. The curves for the cell number and dry weight demonstrate changes in the coordination between the processes of cell growth and division at various growth rates. The cell division was shown to be asymmetric under the conditions of substrate limitation.     

Maintenance of the differentiated type II cell characteristics by culture on an acellular human amnion membrane

We have developed a Culture system for guinea pig alveolar type II cells using an epithelium-denuded human amnion membrane as a substratum. The differentiated morphology was maintained for 3 wk by both air-interface feeding and immersion feeding when type II cells were cultured on the basement membrane side of the amnion with fibroblasts on the opposite side (coculture). Functionally high levels of surfactant protein B (SP-B) and C (SP-C) messenger ribonucleic acids (mRNAs) were expressed even after the 3-wk cultivation and surfactant protein A mRNA was detected on day 10 of the culture. The differentiation was also maintained when fibroblasts were cultured on lower chambers of the culture plates (separate culture). In contrast, culture of type II cells without fibroblasts (monoculture) could not preserve the mature morphology. When the monoculture was supplemented with keratinocyte growth factor or hepatocyte growth factor, a monolayer of rather cuboidal type II cells with apical microvilli was maintained. However, the percent area of lamellar bodies in these cells was significantly less than that in freshly isolated type II cells, and mRNA expressions of SP-B and SP-C were also considerably suppressed. These findings suggest that other growth factors or combinations of these factors are necessary for the maintenance of the differentiated phenotype. As substratum, a permeable collagen membrane or a thin gel layer of Engelbreth-Holm-Swarm mouse sarcoma extracts did not preserve the mature characteristics. This culture system using an acellular human amnion membrane may provide novel models for research in type II cells.