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Several cell lines have been derived from an ocular melanoma obtained from an enucleated patient. Three cell types are observed during the time in culture of all the cell lines under study. Two of them have epithelial and spindle shape respectively. A third cell type, having a spheroidal shape, is formed from spindle cells and may be transformed into epithelial cells upon re-seeding. Further experiments showed that the same cell may change of shape following the cycle: spheroidal-->epithelial-->fusiform-->spheroidal. Scanning microscopy shows the coexistence of the three cell shapes in the same culture and the presence of several filaments and processes protruding at the surface of the cells. Transmission electron microscopy shows that the cell lines, in general, contain melanosomes empty or fairly pigmented and several filaments and microtubules. The presence of melanin may be stimulated by seeding of melanoma cells over a "feeder layer" of fibroblasts.

Cell cultures obtained from human uveal tumours have been used as experimental model to study the lethal effect consecutive to the neutron capture reaction on boron incorporated into cells as borophenylalanine. An irradiation with a neutron fluence of 6 x 10(9) n cm-2 reduced the number of viable cells by about 30%.

1. Little information is currently available on protein turnover during chronic protein loss situations. We have thus measured the whole-body and tissue protein fractional synthesis rates (ks), the whole-body fractional protein degradation rate (kd), the capacity for protein synthesis (Cs) and the efficiency of protein synthesis (kRNA) in vivo in fed and fasted (1, 5 and about 9 days) 400 g rats. 2. One day of starvation resulted in a reduced ks and an increased kd in the whole body. ks was selectively depressed in skeletal muscles, mainly owing to a reduced kRNA, and was not modified in heart, liver and skin. The contribution of skin to whole-body protein synthesis increased by 39%. 3. During the phase of protein sparing (5 days of fasting), kd in the whole body decreased below the control fed level. ks in skeletal muscles was sustained because kRNA was restored to 82-98% of the control value. 4. Rats were in a protein-wasting phase after 9 days of starvation. kd in the whole body did not increase and was actually 78% of the value observed in fed animals. By contrast, ks in the whole body and tissues decreased to 14-34% of the control values, owing to reductions in both Cs and kRNA. Whatever the duration of the fast, the contribution of the skin to whole-body protein synthesis largely exceeded that of skeletal muscle. 5. The present findings suggest that the main goal in the treatment of chronic protein loss should be to sustain protein synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of long-term starvation on the activities of sucrase, lactase, and aminopeptidase, and on their respective mRNA were determined in the small intestine of thyroidectomized and sham-operated adult rats. Thyroidectomy reduced the protein loss at the level of the intestinal brush border membranes during starvation. Prolonged fasting caused a significant decrease in sucrase activity, but thyroidectomy partly prevented this effect. However, the amount of the corresponding mRNA dropped during long term starvation without incidence of thyroidectomy. Lactase activity in the brush border membranes was increased by starvation, and thyroidectomy caused a further elevation of the enzyme activity. Simultaneously, lactase mRNA content rose only slightly compared to the enzyme activity. Aminopeptidase activity and mRNA content decreased during starvation and thyroidectomy did not prevent this process. These results indicate that intestinal hydrolases respond non-coordinately to long-term food deprivation. In addition, the thyroid status of the animals has a direct influence on the adaptation of several brush border hydrolases to starvation. This suggests that the drop in plasma thyroid hormones during fasting allows a better maintenance of protein content and of hydrolase activities in the brush border membranes of the small intestine. These adaptive processes seemed to be partly controlled at a post-transcriptional level.