Morphological analysis of articular cartilage biopsies from a randomized, clinical study comparing the effects of 500-730 kDa sodium hyaluronate (Hyalgan) and methylprednisolone acetate on primary osteoarthritis of the knee.

OBJECTIVE: Histomorphometric study on cartilage samples taken from osteoarthritic human knees before and 6 months after intraarticular injections of a specific fraction (500-730 kDa) of hyaluronan. The results obtained with hyaluronan were compared with the results of methylprednisolone acetate treatment. METHODS: Twenty-four subjects with primary osteoarthritis (OA) of the knee were considered. Eleven patients were treated with Hyaluronan (Hyalgan), 20 mg/2 ml once a week for 5 weeks) and 13 with methylprednisolone (Depo-Medrol, 40 mg/1 ml once a week for 3 weeks). At the time of baseline and after 6 months from the start of treatment, biopsies of cartilage were taken and processed for electron microscopy. Articular surface morphology, territorial matrix, chondrocyte number and ultrastructure were characterized by a set of morphometric parameters. Samples from 19 informed patients showing no arthroscopic sign of OA were also used for comparison. RESULTS: Six months after hyaluronan treatment a significant reconstitution of the superficial layer were observed together with an improvement in chondrocyte density and territorial matrix appearance. Furthermore, chondrocytes appeared significantly improved in their metabolism, as indicated by the increased extension of the synthetic structures and mitochondria with respect to the organelles having catabolic or storage functions. Hyaluronan treatment produced results that were significantly superior to those delivered with Methylprednisolone in almost all the morphometric estimators. CONCLUSIONS: These results cannot be explained simply by temporary restoration of the synovial fluid viscoelasticity, and provide further evidence that the specific fraction of hyaluronan used in this study is a useful tool in OA treatment, with a potential structure-modifying activity.

Peripheral neuropathy induced by intravenous administration of vincristine sulfate in the rabbit. An ultrastructural study.

The lack of a suitable animal model for the peripheral neuropathy that often follows the systemic administration of the chemotherapeutic agent vincristine sulfate (VCR) has hampered the correlation between experimental and clinical patterns of this neuropathy. New Zealand rabbits have been recently found to develop, after iv injection of a VCR total dosage similar to that used in humans, a peripheral polyneuropathy characterized by electrophysiological changes that overlap those observed in the clinical setting. The present study was aimed at investigating the ultrastructural features of 3 different nerves (sural, peroneal, and medial gastrocnemius) in rabbits treated with 3 VCR doses that fall within the range (0.2-0.3 mg/kg i.v.) known to be efficacious chemotherapeutically and active neurotoxicologically. Regardless of the dose and the nerve under examination, histopathologic alterations appeared in the form of an overall loss of myelinated fibers, accompanied by successful attempts of regeneration and remyelination. Fibers undergoing Wallerian degeneration were characterized by an axoplasm, which was either watery-flocculent or divided in 2 or more regions as a consequence of ingrowing Schwann cell processes from the adaxonal surface. These ingrowths tended to isolate axoplasmic areas, retaining a fairly normal structure from other areas already crowded with altered organelles and cytoskeletal elements. In any event, neurofibrillary accumulations were rarely seen. These patterns are discussed with reference to those reported in the ultrastructural studies of human cases and confirm the suitability of rabbit as an animal model for VCR-induced peripheral neuropathy.

Perineurium of sciatic nerve in normal and diabetic rodents: freeze-fracture study of intercellular junctional complexes.

A comparative study has been carried out using the freeze-fracture technique on the perineurium of the sciatic nerve from normal and diabetic mice (C57Bl/Ks, BALB/c and CD1 strains) and rats of various ages. The replicas showed that tight junctions connected perineurial cells both within the same cell layer (zonulae occludentes) and between adjacent layers (maculae occludentes). In neonates, a number of zonulae occludentes were characterized by short, incomplete or fragmented ridges at various intervals from each other; in adults, tight junctions appeared as 'mature' networks of interconnected, branching and/or anastomosing strands. Zonulae occludentes of diabetic mice also exhibited frequent interruption of the strands and reduction in the branching of strands. Gap junctions occurred in both zonulae and maculae occludentes of normal and diabetic rats at all ages. In the C57Bl/Ks strain such junctions occurred more frequently in zonulae occludentes of diabetic animals. It is suggested that perineurial cells are coupled by gap junctions to allow fast transfer of ions and small-sized molecules across the layers; under pathological conditions, such as diabetes, the increase in cell-to-cell signalling may be important in controlling the abnormal metabolic situation.

[Spontaneous reparation of post-traumatic tympanic perforation: an experimental study in rats]. / Riparazione spontanea della perforazione timpanica post-traumatica: studio sperimentale nel ratto.

In most patients tympanic membrane perforation spontaneously repairs itself. Nonetheless, in several cases the perforation persists due either to traumatic or phlogistic damage. Although the membrane perforation healing process has been under study for over a century there are still two contrasting theories. One of these theories asserts that repair takes place through the growth of granulation tissue while the other believes that epithelial migration is at the basis of healing. In the present study an experimental animal model (rat) was used in order to assess the staging of the natural evolution of post-traumatic membrane perforation and to characterize, from a morphological and sub-microscopic point of view, the cellular population and microstructural aspects of the extracellular matrix. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to evaluate the progress in tympanic membrane healing and to make a comparison with the most recent theories. Eighteen Sprague-Dawley rats weighing 230-260 gr of the same age (10 weeks) were used in the study. The animals were anesthetized by intraperitoneal injections of Na-pentobarbital (NembutalR) (45 mg/Kg) and, under operating microscope, bilateral perforation of the upper rear quadrant of the pars tensa was performed with a myringotomy lancet. The animals were subjected to periodic follow-ups over next 30 days. Three animals were sacrificed during each control and the tympanic membrane was removed for TEM and SEM study. On the basis of the present study the following conclusions can be drawn: a) primary healing of the lesion is through granulation tissue; b) the healed T.M. is composed of three normal layers as is the normal T.M.; c) the presence of fibroblasts in the intermediate neoformed fibrous layer leads one to conclude that its extracellular matrix is produced and organized "in situ"; d) the neoformed lamina propria has a disorganized, fibrous structure.

Intraarticular sodium hyaluronate injections in the Pond-Nuki experimental model of osteoarthritis in dogs. II. Morphological findings.

The effect of the intraarticular sodium hyaluronate (HA) injection on the osteoarthritic knee joint has been evaluated in dogs using an experimental model of osteoarthritis induced by sectioning the anterior cruciate ligament. Seven weeks after surgery, the damage, graded according to Mankin's scale, was significantly reduced in knee joints treated with HA from the second week postsurgery compared to untreated joints. When intraarticular HA therapy was initiated after the seventh week, osteoarthritis progression was still reduced compared to controls. Both morphology and morphometry showed a beneficial effect of HA on the cartilage response to the damage, as well as a clearcut inhibitory effect on the development of the fibroblastlike cell layer on the articular cartilage in untreated joints. The beneficial effects on the cartilage integrity and response to osteoarthritic damage might be related to a primary effect of HA on the cartilage surface. However, these effects do not exclude the possibility that, in addition, HA might act on the synovial membrane by limiting the synovial reaction.