Hiroyuki Warita

Effect of Nitric Oxide on the Recovery of the Hypofunctional Periodontal Ligament

The relationship between occlusal stimuli and a hypofunctional periodontal ligament (PDL) structure has been reported, though changes in occlusal recovery conditions were still unclear. Nitric oxide (NO) produced by NO synthase (NOS) is considered a factor for vascular and immune system control, and it increases according to mechanical stimuli. The objective of this study was to examine the relationship between NOS and occlusal stimuli in PDL by comparing hypofunction with occlusal recovery. The study focused on the expression of endothelial NOS (eNOS) and inducible NOS (iNOS). Their expression significantly decreased in occlusal hypofunction compared with the control group and increased close to normal in an occlusal recovery group. The change in the immunopositive area was more dramatic than the immunopositive cell number. Moreover, the rate of iNOS increase was higher than that of eNOS. This study suggests that NO plays an important role in the recovery of the hypofunctional PDL.

Alterations of the Rat Temporomandibular Joint in Functional Posterior Displacement of the Mandible

Functional malocclusion that induces posterior condylar displacement may affect the remodeling processes of the temporomandibular joint structures. We tested the hypothesis that intermittent posterior condylar displacement due to functional malocclusion traumatizes condylar cartilage and joint innervated nerve fibers. Thirty-nine eight-week-old Wistar rats were used. To induce functional posterior condylar displacement, guiding appliances were attached to maxillary incisors of 24 rats for four, seven, and 14 days. Fifteen normal rats served as controls. Sections were stained with hematoxylin and eosin or processed for immunohistochemistry of protein gene product 9.5 and growth-associated protein-43 (GAP-43). Functional posterior condylar displacement led to a diminution in proliferative cells, reduction in cartilage width, and re-expression of GAP-43-immunoreactive nerve fibers. These results indicate that intermittent posterior condylar displacement due to functional malocclusion causes dysfunctional remodeling of condylar cartilage and nerve injury.

CONFOCAL LASER SCANNING-MICROSCOPIC OBSERVATIONS ON THE THREE-DIMENSIONAL DISTRIBUTION OF OXYTALAN FIBRES IN MOUSE PERIODONTAL LIGAMENT

The purpose was to improve confocal laser scanning-microscopic (CLSM) techniques to observe the three-dimensional (3-D) distribution of oxytalan fibres in mouse periodontal ligament and to clarify the 3-D relation between those fibres and blood vessels. As aldehyde fuchsin is a contrast agent and the specific wavelength affects the depth of penetration, CLSM reflectance imaging of oxytalan stained with aldehyde fuchsin after oxidization provides strong contrast. Oxytalan fibres, whose precise roles have not yet been clarified, are connective tissue fibres present in human periodontal ligament in addition to collagen fibres. Despite many studies on their arrangement and biomechanical characteristics, their 3-D distribution in relation to other structures has never been reported. Mandibular first molars of mice were sectioned mesiodistally, pre-oxidized by monopersulphate compound (Oxone), stained with aldehyde fuchsin and examined by CLSM. CLSM images clearly revealed the 3-D distribution, and relation of oxytalan fibres to blood vessels and other structures, as well as their branching patterns in the periodontal ligament. The marked anatomical correlations between the direction, distribution and branching patterns of oxytalan fibres and blood vessels suggest that they interact to perform a specialized physiological role in the periodontal ligament.

HIGH LEVELS OF GM1-GANGLIOSIDE AND GM1-GANGLIOSIDE β-GALACTOSIDASE IN THE PAROTID GLAND: A New Model for Secretory Mechanisms of the Parotid Gland

A new model for the subcellular basis of parotid secretion is presented in this article. GM(1)-ganglioside, typically found in neural tissues, is shown to be abundant in the parotid gland. This ganglioside may play a central role in membrane turnover mechanisms underlying exocytosis/endocytosis in its role as a promoter of membrane fusion or a fusogen. The lysosome and lysosomal hydrolases also play a central role in this model in catabolism of GM(1)-ganglioside. Consequently, high levels of the lysosomal hydrolase acidic beta-galactosidase are demonstrated in the salivary gland. GM(1)-gangliosidosis of the parotid glands, as described in mice, appears to be the first single-gene heritable disease found so far in the salivary glands.