Effects of calcium phosphate cement on the peripheral nerve fibers.

Calcium phosphate cement (CPC) is a bioactive ceramic substance. To clarify the effects of CPC on the peripheral nerve, we applied CPC on the peripheral nerve fibers of experimental animals and investigated the nerve fibers by electron microscopy and by immunoblotting analysis using an anti-myelin-associated glycoprotein (anti-MAG) antibody. The results showed that there was neither axonal sprouting at the nodes of Ranvier nor down-regulation of MAG beyond the normal level in the nerve fibers. These findings suggest that there is no harm in using CPC near the peripheral nerve fibers.

Alveolar ridge augmentation using various bone substitutes--a web form of titanium fibers promotes rapid bone development.

Alveolar ridge augmentation with beta-tricalcium phosphate (beta-TCP) granules, calcium phosphate cement (CPC) powder and web form of titanium fibers (TW) added to Platelet-Rich-Plasma (PRP) was histologically observed for 5 months by the experiments using the maxilla of rabbits. As a result, TW was thus found to promote the rapid bone development within a period of less than 5 months, because TW had an appropriate gap between the titanium fibers for new bone progression. However, titanium fibers remained intact within the maxilla. The CPC powder was transformed into dense cement and also remained intact in the bone. These residual materials must be obstacles to perform the placement of dental implants. On the other hand, beta-TCP granulations were gradually replaced by the new bone, but this process took about 5 months to be completed. Consequently, for an ideal alveolar bone substitute, there needs to be a suitable gap formation within the substitute, such as TW, and properties of total bone replacement, such as that seen in beta-TCP granules.

Ultrastructural localization of alpha E-catenin in the rat sciatic nerve.

Alpha E-catenin is included in the same category as alpha N-catenin, and both of them have been identified as subtypes of alpha-catenin. A previous study issued from our laboratory demonstrated that alpha N-catenin is localized in the axoplasm of unmyelinated peripheral nerves, whereas the localization of alpha E-catenin in the peripheral nervous system has not yet been reported. The present study was focused on the distribution of alpha E-catenin in the rat sciatic nerve. By electron microscopy using immunocytochemical methods, alpha E-catenin immunoreactivities were generally detected in the Schwann cell cytoplasm of unmyelinated nerve and the outer loop of myelinated nerve. Those findings suggest that alpha E-catenin may be associated with Schwann cell-Schwann cell or axon-Schwann cell contacts.

N-/R-cadherin expression in dorsal root ganglia and spinal cord.

Localizations of N- and R-cadherins in dorsal root ganglia and lumbar spinal cord of the chick were immunocytochemically examined. As a result, N- and R-cadherin appeared to be co-localized on plasmalemma of neurons in dorsal root ganglia that were in contact with satellite cells, whereas there was no expression in neurons of the ventral horn. These findings indicate the possibility that expression pattern of cadherins in the peripheral neuron differs with its functional property (e.g. sensory or motor).

Management of oral leukoplakia by laser surgery: relation between recurrence and malignant transformation and clinicopathological features.

OBJECTIVE: The aim of the present study was to assess the clinical usefulness of laser surgery for oral leukoplakia. BACKGROUND: Recurrence and/or malignanT transformation of oral leukoplakia have occasionally been observed following laser surgery. It is reported that the rate of recurrence was 7.7-38.1%, while malignant transformation was 2.6-9%. MATERIALS AND METHODS: A total of 154 oral leukoplakias from 116 patients were treated in our department. Comparisons with the rate of recurrence, malignant transformation and clinical futures, epithelial dysplasia, location, and treatment procedure were examined. To evaluate recurrence and malignant transformation, the cases were restricted to those with a minimum follow-up of 6 months. RESULTS: A total of 97 lesions fulfilled this criterion. The rate of recurrence had no association with the location or the epithelial dysplasia, although it differed with the treatment procedure. The rate of recurrence in laser surgery was approximately 29%. Malignant transformation was observed in four of 97 lesions. They were observed in 13.6% of tongue cases and 1.8% of gingival cases. Three of four lesions were treated with excision surgery, and the remaining one treated with laser vaporization. Only 1.2% malignant transformation in laser surgery was revealed. CONCLUSION: Laser excision is suitable for leukoplakia cases on non-keratinized epithelia (i.e., the tongue and buccal mucosa), while laser vaporization is suitable for the gingival cases. Management of oral leukoplakia prevents not only recurrence and malignant transformation, but also postoperative dysfunction. We believe that laser surgery is an excellent procedure.

Alpha E- and alpha N-catenin expression in dorsal root ganglia and spinal cord.

The localization of alpha E- and alpha N-catenin in dorsal root ganglia and spinal cord was examined immunocytochemically. Alpha E- and alpha N-catenin appeared to be co-localized in cell bodies of neurons in dorsal root ganglia, but alpha N-catenin was not expressed in cell bodies of neurons in the ventral horn that showed alpha E-catenin expression. These findings indicate the possibility that the type of alpha catenin expressed in neurons differs with its functional property (e.g. sensory or motor).