Effect of methylmercuric chloride on gangliosides of mouse neuroblastoma cells in culture

The effect of methylmercuric chloride (CH3HgCl) on the levels of gangliosides in mouse neuroblastoma cells (NBP2) in culture was studied. The treatment of NB cells with low concentrations (0.1 microM and 0.2 microM) of CH3HgCl, which did not affect the growth rate or morphology, caused an increase in the level of the GM3 ganglioside without changing the level of other gangliosides. The treatment of NB cells with higher concentrations (0.5 microM and 1 microM) of CH3HgCl, which inhibited the growth of NB cells, caused a decrease in the level of GM3 and an increase in the level of GM2. These results show that alterations in the levels of specific gangliosides can be observed in cells which do not exhibit any detectable change in growth rate or morphology. This change may be associated with subtle changes in brain functions, including behavioral and psychological changes, after exposure to low concentrations of organic mercury.

Prognostic index for clinical Stage I cutaneous malignant melanoma

Thirteen variables were evaluated for their significance in predicting the survival of 148 patients in a retrospective study with clinical Stage I cutaneous malignant melanoma. The variables studied were histological type, tumor thickness, level of invasion, mitotic activity, pigmentation type, existence of ulceration, presence of lymphocytic infiltration, cell type, sex and age of the patient, site of melanoma, and wide local excision preceded or not by contact radiotherapy and associated or not with lymphadenectomy. When these variables were individualized, only seven were significantly related to survival: histological type; tumor thickness; level of invasion; mitotic activity; pigmentation type; existence of ulceration; and sex of the patient. Multivariate analysis based on Breslow's version of the Cox proportional-hazards model was performed on a group of 110 patients. This analysis demonstrated that 5 of the original 13 variables (i.e., mitotic activity, tumor thickness, sex, lymphadenectomy, and site of primary melanoma) could be used to develop a prognostic model. A Gompertz distribution which provided for an appropriate smoothing of the Breslow model estimates was used to derive a simple prognostic index and to predict the survival of individual patients. Fifty-four patients in a prospective study were subsequently evaluated with the Gompertz model in order to test the prognostic accuracy of the model for the five variables.

Use of synthetic polymers for biomedical application

Synthetic polymers have been used for numerous biomedical and pharmacologic purposes. These include prosthetic implants, suture material and drug carriers. Long-term results are often unpredictable despite the continuing exposure to an often hostile physiologic environment. Biocompatibility in general is influenced by physical, chemical and structural properties of these polymers. While surface phenomena are important, reactions related to the bulk itself are not negligible. Methods for analyzing surface and bulk interfaces are described. These tests are directly applicable to studies of polysiloxane (silicone) and polyurethane cardiac pacing leads.