1/f ruffle oscillations in plasma membranes of amphibian epithelial cells under normal and inverted gravitational orientations.

Membrane ruffle fluctuations of amphibian epithelial cells A6 (CCL102) cultured in normal and upside down oriented plates have been analyzed through video microscopy. Our results reveal that their edge ruffle fluctuations exhibit a stochastic dynamics with 1/f(alpha) power spectrum over at least two decades at low frequencies and long range correlated, self-affine lateral border profiles. In a few and small areas of the membrane, probably nearby focal contacts, we found periodic oscillations which could be induced by myosin driven contraction of stress fibers. Furthermore, whereas the different gravitational orientations had none or little effect on the structure (power spectra and surface roughness) of these membrane ruffle fluctuations, their dynamic parameters were differentially affected. Indeed, the decay time of ruffles remained unchanged, but the period of lamellipodia oscillations near the focal adhesion points was significantly altered in A6 cells cultured upside down.

Morphology transitions induced by chemotherapy in carcinomas in situ.

Recently, we have proposed a nutrient-limited model for the avascular growth of tumors including cell proliferation, motility, and death [S. C. Ferreira, Jr., M. L. Martins, and M. J. Vilela, Phys. Rev. E 65, 021907 (2002)], which qualitatively reproduces commonly observed morphologies for carcinomas in situ. In the present work, we analyze the effects of distinct chemotherapeutic strategies on the patterns, scaling, and growth laws obtained for the nutrient-limited model. Two kinds of chemotherapeutic strategies were considered, namely, those that kill cancer cells and those that block cell mitosis but allow the cell to survive for some time. Depending on the chemotherapeutic schedule used, the tumors are completely eliminated, reach a stationary size, or grow following power laws. The model suggests that the scaling properties of the tumors are not affected by the mild cytotoxic treatments, although a reduction in growth rates and an increase in invasiveness are observed. For the strategies based on antimitotic drugs, a morphological transition in which compact tumors become more fractal under aggressive treatments was seen.

Reaction-diffusion model for the growth of avascular tumor.

A nutrient-limited model for avascular cancer growth including cell proliferation, motility, and death is presented. The model qualitatively reproduces commonly observed morphologies for primary tumors, and the simulated patterns are characterized by its gyration radius, total number of cancer cells, and number of cells on tumor periphery. These very distinct morphological patterns follow Gompertz growth curves, but exhibit different scaling laws for their surfaces. Also, the simulated tumors incorporate a spatial structure composed of a central necrotic core, an inner rim of quiescent cells and a narrow outer shell of proliferating cells in agreement with biological data. Finally, our results indicate that the competition for nutrients among normal and cancer cells may be a determining factor in generating papillary tumor morphology.

Fractal patterns for cells in culture.

The present study aims to understand the growth of human malignant tumours in vitro, using the geometry of fractals as a method of analysis. The fractal dimensions of HN-5 and MDCK cell growth patterns have been measured. The first results may suggest the possibility of distinct growth processes characterized by different (time-dependent) effective fractal dimensions for MDCK and HN-5 cells. If this is true, the fractal dimensions may yet prove to be a useful discriminant for comparing different diagnostic categories.

A simple epithelial cell line (MDCK) shows heterogeneity of desmoglein isoforms, one resembling pemphigus vulgaris antigen.

The epidermal blistering disease, pemphigus vulgaris (PV), is caused by circulating autoantibodies that react with a desmosomal glycoprotein desmoglein (Dsg3). This antigen is expressed only in stratified epithelial tissues. Here we show that the simple epithelial canine kidney cell line, MDCK, expresses at least two desmoglein isoforms recognised by different monoclonal antibodies. One of these isoforms is a 130 x 10(3) M(r) polypeptide that is recognised by both PV autoantisera and a monoclonal antibody reactive with a cytoplasmic domain of human Dsg3. Antibodies in PV sera bind to the surface of MDCK cells but not cause loss of intercellular adhesion. This is the first demonstration of the expression of a polypeptide related to human PV antigen by a simple epithelial cell type.

Immunohistochemical staining with monoclonal antibody 32-2B to desmosomal glycoprotein 1. Its role in the histological assessment of urothelial carcinomas.

A series of transitional cell carcinomas of bladder were stained immunohistochemically with the monoclonal antibody, 32-2B, to desmosomal glycoprotein 1. All of the sections showed positive staining with the antibody. Assessment of staining intensity, by 3 independent examiners, revealed a strong negative correlation between density of desmosomal staining and degree of invasion (P = 0.012). Nests of strongly staining cells were identified in several invasive tumours, possibly indicating early squamous differentiation. Invasive tumour cells in the subepithelial stroma also stained strongly with the antibody. Correlation with clinical course, however, revealed no significant association between desmosomal staining and the incidence of recurrence or progression. It is suggested that staining with this antibody may be of value in detecting both stromal invasion and early squamous differentiation of transitional cell carcinomas. Both this and previous studies emphasise the value of this antibody as an epithelial marker in neoplasia.

Monoclonal antibody to desmosomal glycoprotein 1--a new epithelial marker for diagnostic pathology.

Desmosomes are intercellular adhesive junctions that occur in almost all epithelia and should therefore be useful as epithelial markers in tumour diagnosis. Here, we describe a monoclonal antibody, 32-2B, to a major desmosomal glycoprotein (dgl) which reacts with human tissues in paraffin sections. This antibody was tested for its ability to stain epithelia and tumours. It reacted with all epithelia tested and with every specimen of a wide range of carcinomas. It also stained meningiomas, another desmosome-containing tumour. It did not stain other types of tumours including lymphomas, melanomas, and various sarcomas, or normal tissues which lack desmosomes. These characteristics demonstrate that 32-2B is a reliable epithelial marker that may have a useful role in diagnostic histopathology.