The glioma-associated gangliosides 3'-isoLM1, GD3 and GM2 show selective area expression in human glioblastoma xenografts in nude rat brains.

This work describes the in vivo expression and distribution of glioma-associated gangliosides (GD3, GM2, 3'-isoLM1) in a novel human brain tumour nude rat xenograft model. In this model, the tumours, which are established directly from human glioblastoma biopsies, show extensive infiltrative growth within the rat brain. This model therefore provides an opportunity to study ganglioside expression not only within the macroscopic tumour, but also in brain areas with tumour cell infiltration. The ganglioside expression was studied by confocal microscopy of immunostained brain sections using antiganglioside monoclonal antibodies. Xenografts from four human glioblastoma multiformes were established in rats and the brains removed after 3-4 months. Ganglioside GD3 was expressed in the tumour parenchyma while ganglioside 3'-isoLM1 was more abundantly expressed in the periphery of the tumour associated with areas of tumour cell invasion. GM2 expression was only seen in one tumour, where it was located within the main tumour mass. Double staining with a pan antihuman monoclonal antibody (3B4) and the antiganglioside monoclonal antibodies confirmed that the ganglioside expression was associated with tumour cells. This work supports the concept of different biological roles for individual gangliosides and indicates that antibodies or ligands directed against GD3 and 3'-isoLM1 might be complementary when applied in the treatment of human glioblastomas.

Assessing the need for Clinical Breast Examination (CBE) training: the Oregon experience.

BACKGROUND: Despite the widely held perception that CBE training has high priority among the continuing medical education (CME) needs of breast health care providers, there is actually little published information to support this notion. METHODS: The authors conducted a statewide needs assessment mail survey of providers regarding a number of potential CME needs, including CBE training. RESULTS: Of the 4,179 surveys from the single mailing, 1,427 were returned (34% response rate). Six categories of provider types responded; 51% were physicians and 23% were nurse practitioners. Fifty-nine percent of the respondents were female; 96% felt that routine CBE was an important or very important part of providing breast care. Although 79% of all respondents performed CBE at least weekly and 41% performed more than ten CBEs/week, 80% were interested in receiving some form of CME regarding CBE, and 79% of those who performed CBE at least weekly were interested in receiving skill-based CBE training. CONCLUSIONS: Despite the respondent bias inherent in survey studies, it can be concluded that there is indeed a CME need for CBE training, even among providers who perform CBE frequently. Based on these findings the authors are implementing a statewide CME program of CBE training.

Monoclonal anti-GD3 antibodies selectively inhibit the proliferation of human malignant glioma cells in vitro.

The frequently occurring alteration of ganglioside expression in tumor cells has been implicated to play a role in the uncontrolled growth of these cells; antibodies to such gangliosides might affect tumor cell growth. We have studied the effect of IgM monoclonal antibodies to two glioma-associated gangliosides, GD3 and GM2, on cell proliferation of four human glioma cell lines and one renal tumor cell line. Of the two anti-ganglioside antibodies tested, only the anti-GD3 antibody resulted in a significant (p<0.005) inhibition of cell proliferation as measured by thymidine incorporation and Brd-U labeling, after 24h incubation. The effect was not dependent on any serum factor and no increased cell death was observed. All cell lines contained higher or similar amounts of GM2 than GD3, and both antigens were shown to be expressed on the cell surface and accessible to antibodies. The selective effect of anti-GD3 antibodies as contrasted to the inactivity of anti-GM2 antibodies suggests a possible role for ganglioside GD3 in tumor cell proliferation.

The effect of neomycin on PDGF-induced mitogenic response and actin organization in cultured human fibroblasts.

Actin organization and DNA synthesis were studied in cultured, serum-starved, subconfluent human fibroblasts in response to human recombinant platelet-derived growth factor (PDGF)-BB and neomycin, an inhibitor of phosphoinositide (PI) turnover. The labeling of F-actin with TRITC-phalloidin showed that PDGF (10 ng/ml) and neomycin (3.5 mM) induced, within minutes, similar changes in the actin cytoskeleton and when used together potentiated each other's effects. PDGF stimulated a twofold increase in DNA synthesis, as shown by [3H]thymidine incorporation, 48 h after the beginning of incubation. Neomycin did not induce DNA synthesis but reduced the mitogenic response to PDGF to control levels. Stimulation of DNA synthesis was correlated with an intense increase in lamellipodia formation and ruffling, whereas inhibition of the DNA synthesis was correlated with the development of elongated cell shape with few ruffles and lamellipodia, similarly to untreated control cells. Our findings support the conclusion that early changes in the actin cytoskeleton and induction of DNA synthesis are separable biological processes that are mediated by different pathways. The inhibitory effect of neomycin on PDGF-induced DNA synthesis was dose-dependent during the first 24 h of PDGF incubation, after which the cells were irreversibly and maximally stimulated to synthesize DNA. Results of experimental treatments with neomycin at various times during the incubation with PDGF indicate that the critical period during which PDGF acts to stimulate DNA synthesis is after the 1st h but before the 12th h of incubation.

PDGF and neomycin induce similar changes in the actin cytoskeleton in human fibroblasts.

The addition of platelet-derived growth factor (PDGF) to serum-starved fibroblasts induces increased motility, formation of lamellipodia, increased ruffling activity, and actin ring structures associated with dorsal ruffles. Involvement of the phosphatidylinositol cycle (PI-cycle) in these morphological changes was investigated by observing the effects of neomycin, an inhibitor of the PI-cycle, on cultured human foreskin fibroblasts. The role of actin in the changes was investigated by using cytochalasin D (CD). Actin in detergent-extracted cells was labelled with TRITC-phalloidin and examined with fluorescence microscopy. Using PDGF and neomycin simultaneously potentiated lamellipodia formation, ruffling activity, as well as the number of cells with actin rings. Furthermore, neomycin by itself induced morphological changes similar to those induced by PDGF. Quantitation of actin rings showed dose and time dependency for PDGF and neomycin respectively, with a maximal number of cells containing rings after 15 min of exposure to either 3.5 mM neomycin or 10 ng PDGF/ml. Comparing the two substances, PDGF induced ring formation in a greater number of cells. These processes were inhibited by the presence of CD. PDGF- and neomycin-induced changes in the actin cytoskeleton were also observed in human embryonic lung fibroblasts, human glial cells, and embryonic mouse fibroblasts, all of which are known to express PDGF-receptors. In conclusion, the present study indicates that an increased turnover of the PI-cycle is not essential for the changes in actin organization induced by PDGF.