Salvatore Caiazza

Bone regeneration guided by resorbable collagen membranes in rabbits : a pilot study

Artificial cross-shaped intrabony defects were created in the mandibles of 12 rabbits and the cavities covered with Type I highly cross-linked resorbable collagen membranes for 30 days. Similar cavities were prepared in three control animals and left uncovered for the same time period. Morphological and analytical data were obtained by means of light microscopy, scanning electron microscopy, and x-ray energy-dispersive spectrometry. After the experimental period, the membrane covered cavities were completely filled with regenerated bone. In the control specimens, the artificial cavities were occupied by fibrous connective tissue. (Implant Dent 1993;2:101–105)

Evaluation of guided bone regeneration in rabbit femur using collagen membranes.

&NA; The aim of the study was to evaluate the mechanical performance and the structure of neoformed bone around hydroxyapatite‐coated titanium fixtures according to guided bone regeneration techniques. Ten hydroxyapatitecoated titanium fixtures were inserted in the femurs of five rabbits, in which a cortical defect was created and after the insertion of the fixture, covered with a resorbable membrane obtained from bovine Achilles tendon collagen Type I (A implant). In the same femur, a second fixture was inserted in similar cavities without application of the membrane (B implant). After 60 days, the animals were sacrificed, and block sections of the femoral bone con taining the implants were embedded in polymethylmetacrylate and subjected to tensile shear‐stress at break testing. After the detachment of the implants from the bone, their surfaces were examined with a scanning electron microscope. Tensile shear‐stress values for A and B implant specimens were comparable to some extent, but the former had a lower performance. In this regard, scanning electron microscope observations showed that the neoformed cortical bone present cervically around implant A was much thicker than around implant B. (Implant Dent 2000;9:219‐225)

Fluosol 43 particle localization pattern in target organs of rats

Perfluorocarbons (PFCs), chemically inert fluorinated organic compounds with high binding capacity for O2, are under discussion as substitutes for erythrocytes. Given the paucity of E.M. observations after their use, the aim of this study was to provide more extensive ultrastructural data about PFC particle size in the emulsion and about the localization pattern in organs of rats after infusion of Fluosol 43. Attention has been focused on the particle relationships with subcellular structures and on the subsequent histopathological implications.

Alteration of organized structure of biofilm formed by Staphylococcus epidermidis on soft contact lenses

The effect of a nonsteroidal antiinflammatory drug commercially available in eye drop form (sodium diclofenac) was assayed for its ability to affect biofilms formed by clinical Staphylococcus epidermidis isolates. Biofilms produced by one strain positive for a slime-associated antigen, suggested to be expressed by more virulent strains, was not affected by sodium diclofenac treatment. On the other hand, biofilm produced by the slime-positive, antigen-negative strain showed dramatic alterations already after short treatments with sodium diclofenac as reported for salicylate and other nonsteroidal drugs. Such results suggest further investigation of the possible use of sodium diclofenac drops in the treatment of ophthalmic infections in soft contact lens wearers.

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

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.

Influence of dacron tissue thickness on the performance of the Pintucci biointegrable keratoprosthesis: an in vitro and in vivo study.

Purpose. In 1979 Pintucci developed a biointegrable keratoprosthesis with polymethylmethacrylate optical cylinder integrated with a Dacron tissue-colonizable supporting element to avoid the complications caused by the interaction between the haptic element and the eye. The purpose of this article is to compare the colonization of three Dacron fabrics (thicknesses of 0.25 mm, 0.6 mm, and 1.4 mm) in vitro and in vivo to optimize the device performance. Methods. In vitro three different Dacron fabrics were cultured for 3 days with 3.5 × 10 5 human fetal lung fibroblasts and observed with a scanning electron microscope. In vivo three different Dacron fabrics were implanted on the sclera near the superior rectus insertion in the right eye of six albino rabbits and were observed after 4 days with light and scanning electron microscopy. Results. In the in vitro experiments, the cells were preserved and their structure was found to be normal. The 0.25-mm thick fabric was coated only on the surface, and the other fabrics were colonized in three dimensions. In the in vivo experiments, the 0.25-mm thick fabric appeared coated only on its surface. The other fabrics were three-dimensionally colonized and the Dacron filaments appeared embedded in neovascularized connective tissue with minimal foreign body reaction. The 1.4-mm thick colonized fabric showed a substantial loss of pliability. Conclusion. Given that the 0.25-mm thick fabric was coated only by connective tissue, that the 0.6-mm and 1.4-mm thick fabrics were perfectly colonized, and that the 1.4-mm thick fabrics showed a substantial loss of pliability, the 0.6-mm thick fabric haptic part of the Pintucci keratoprosthesis is preferred. For 19 years, the 0.6-mm Dacron fabric Pintucci keratoprosthesis was implanted in 159 eyes with good results, overcoming the apparently inseparable difficulties represented by mechanical anchorage and biointegrability of a keratoprosthesis.

Light and scanning electron microscopy evaluation of the Dacron felt as the haptic part of an improved keratoprosthesis. An in vitro and in vivo study

Abstract The artificial cornea (keratoprosthesis) is indicated in severe ocular diseases not amendable by means of a corneal transplant. In order significantly to reduce the number of the failures due to the epitheIization of keratoprosthesis implants, an improved device with a Dacron haptic part has been developed. The light (LM) and scanning electron microscopy (SEM) observations showed that the Dacron felt is ingrown by ocular tissues, in vitro and in vivo . Fibrous connective tissue stops the epithelial proliferation around the prosthesis by contact inhibition, thus avoiding its encapsulation and/or extrusion. These results may be predictive of the new keratoprosthesis reliability.

Particle migration from haemodialysis circuit: Electron microscopy and microprobe analysis

It has been recognized that storage inflammation in organs of uraemic patients is due to silicone particle migration from tubing segments of the haemodialysis circuit to blood. Nevertheless, iatrogenic storage of foreign material containing Si has been also observed in long-term dialysis patients which, in our Unit, used only PVC or PU-PVC tubings. The origin and the nature of the particulate has been investigated in vivo and in vitro on bioptical samples as well as on cuprophan dialyser and PVC tubing eluates. This study carried out by means of TEM, SEM and microprobe EDS revealed the presence of variously shaped material and particles containing Si in bioptical samples and in eluates. Si containing contaminants were not demonstrated in eluates filtered in absence of the dialyser. This result suggests that leachable products can result from the dialyser and that such release can be an additional risk for uraemic patients.

Rapid dimensional characterization of perfluorocarbon (PFC) particles by means of EM and automatic image analysis methods

Abstract A technique for dimensional characterization of perfluorocarbon particles in artificial blood substitutes by means of electron microscopy and automatic image analysis is reported. This method allows a rapid, simple and direct evaluation of particle size which is strictly correlated to the biocompatibility of perfluorocarbon emulsion.