PEDF (pigment epithelium-derived factor) promotes increase and maturation of pigment granules in pigment epithelial cells in neonatal albino rat retinal cultures.

Pigment Epithelium-Derived Factor (PEDF), purified from human retinal pigment epithelial (RPE) cell culture medium, is a neurotrophic factor which potentiates the differentiation of human Y-79 retinoblastoma cells and increases the survival of cerebellar granule cells. To investigate the effects of PEDF on non-transformed retinal cells, we used primary cultures of neonatal albino rat retinas, where the three principal cell types of the retinal layers (neuronal, glial and epithelial) were all present and focussed our attention on RPE cells, which are of special relevance for retinal pathophysiology. PEDF had a dramatic effect on these cells. They showed a modified phenotype, with larger dimensions, higher cytoplasmic spreading, presence of phagocytic vacuoles, development of wide intercellular contacts, and increase and maturation of pigment granules. These results suggest that PEDF may have a role in regulating RPE cell differentiation.

Perfluorodecalin modifies the pattern of cell arrangement and induces loss of neurites in rat retinal cultures.

Perfluorodecalin (PFD), a high specific weight, water-immiscible perfluorocarbon, previously studied as a potential blood substitute, now is used widely in the field of ophthalmic surgery as a tool for maneuvering intraocular tissues and as a short- or medium-term vitreous substitute. In in vivo experiments, several types of lesions in retinal tissue have been described in conjunction with long-term PFD treatment. To better evaluate the biological effects of PFD on retinal cells, we tested it on primary cultures of rat retina seeded on special cyclopore wells that allow the culture to be fed from the bottom side while the top side is in contact with the water-immiscible compound. We found that PFD changed the pattern of cell arrangement and induced loss of neurites. The modification of cell arrangement was less evident at the periphery of the wells where the amount of PFD, and consequently the pressure exerted, was lower. This observation suggests that the changes may be due more to a physical than to a toxic effect of PFD.

Exceptional case of bone resorption in an osteo-odonto-keratoprosthesis. A scanning electron microscopy and X-ray microanalysis study.

This article reports the findings of investigations on an osteo-odonto-keratoprosthesis in an eye that was enucleated owing to severe complications 12 years after implantation. Scanning electron microscopy and electron probe X-ray microanalysis showed extensive resorption of the bone that was used as a supporting element in the kind of transcorneal prosthesis developed by Strampelli. The destructive process, in addition to surgical trauma, has been associated with the early and recurrent bacterial infections relating to the presence of Staphylococcus epidermidis. The need to control the occurrence of primary bacterial infections in traumatized tissues during operations as well as further infectious situations, given the enhanced antibiotic-resistence of bacteria, is emphasized.

Ultrastructural aspects and clinical implications of PFC/non-phagocytic cell interactions.

Many in vivo studies showed the accumulation of PFC particles in reticuloendothelial cells of target organs such as spleen, lungs and liver. Surprisingly, an uptake of PFCs particles by liver parenchymal cells as well was described by some authors. In order to clarify whether Kupffer cells and/or liver environmental factors could be involved in particle uptake we exposed cultured rat hepatocytes to Fluosol 43. PFC particles were noted, after a 3-hour incubation, in lysosomes. This result suggests that more attention must be paid to liver toxicity of PFC blood substitutes. Isolated mouse myocytes were exposed as well to Fluosol 43 for 3 hours. Preliminary results confirm the absence of the particle uptake previously noted also in our in vivo studies on rat and guinea pig heart-lung preparation. The possible subsequent absence of cytotoxicity at myocardial level could underline the reliability of using optimized PFCs as components of cardioplegic solutions in open heart surgery.

Evaluation by electron microscopy techniques of asbestos contamination in industrial, cosmetic, and pharmaceutical talcs.

Talc powders from national and international markets were analyzed in order to assess their fiber contents and the proportion of asbestos in the fibrous material. Samples of talc powders used as excipients in pharmaceutical and cosmetic preparations demonstrated fiber contents up to 30% of total particles. About a half of the talc powders revealed the presence of asbestos: in five samples chrysotile (a serpentine asbestos) was present, in the other ones tremolite and anthophyllite (an amphibole asbestos). The amounts of asbestos vary up to 90% in the different samples of the fibrous fraction. About 75% of observed asbestos fibers were thinner than 0.4 micron, i.e., below the resolving power of light microscopy which until now was the most utilized technique for evaluating the environmental pollution due to asbestos.

Enhancement of tumor growth by graft-versus-host reaction.

A graft-versus-host reaction was induced in (BALB/c x C5 7BL/6)F(1) mice by intravenous injection of BALB/c spleen cells. Six days later, the mice received subcutaneous grafts of a chemically induced BALB/c sarcoma. The growth of the tumor grafts was accelerated.