Recently, the second mammalian chitinase, designated acidic mammalian chitinase (AMCase), has been identified in human, mouse, and cow. In contrast to the earlier identified macrophage-derived chitinase (chitotriosidase), this chitinase is richly expressed in the gastrointestinal (GI) tract, suggesting its role in digestion of chitin-containing foods as well as defense against chitin-coated microorganisms and parasites. This in situ hybridization study first revealed cellular localization of the gut-type chitinase in the mouse and chicken. In adult mice, the parotid gland, von Ebner's gland, and gastric chief cells, all of which are exocrine cells of the serous type, expressed the gut chitinase mRNA. In the chicken, oxyntico-peptic cells in glandular stomach (proventriculus) and hepatocytes expressed the chitinase mRNA. Because cattle produce the gut chitinase (chitin-binding protein b04) only in the liver, the gut chitinases in mammals and birds have three major sources of production, i.e., the salivary gland, stomach, and liver. During ontogenetic development, the expression level in the parotid gland and stomach of mice increased to the adult level before weaning, whereas in the stomach of chickens intense signals were detectable in embryos from incubation day 7.

L-Glutamate transport by intestinal epithelial cells is an initial step of the entire glutamate metabolism pathway in the gut mucosa. The present study examined the cellular distribution of glutamate transporters in the digestive tract of adult mice using immunohistochemistry and in situ hybridization technique. Expression of EAAC1 mRNA was more intense in the ileum, where the epithelium in crypts and the basal half of intestinal villi showed high levels of transcripts, suggesting an essential role of EAAC1 in differentiating or premature epithelial cells. Electron-microscopically, EAAC1 immunoreactivity was predominantly localized in the striated border of enterocytes. Immunoreactivity for GLT-1 was found in the lateral membrane of epithelial cells at the bottom of gastric glands and at the intestinal crypts, and also in the lateral membrane of secretory cells at the duodenal gland. GLAST immunoreactivity was restricted to the fundic and pyloric glands, and was especially intense in the neck portion of both glands. However, in situ hybridization analysis failed to confirm the expression of GLT-1 and GLAST at the mRNA level, possibly due to limited sensitivity. The strong and specific luminal localization of EAAC1 in the intestinal epithelium suggests that EAAC1 is a predominant transporter of glutamate, at least in the lower part of the small intestine.Glutamate is one of important excitatory neurotransmitters in the central nervous system, and also in the peripheral nervous system such as the enteric nervous system. Neurons and effector cells express a variety of glutamate receptor subtypes (more than 20) for this potent neurotransmitter. For glutamate to fulfill its diverse functions, the existence of a glutamate uptake system with high accumulative power is of critical importance, because the high-affinity glutamate transport prevents the extracellular glutamate concentration from reaching neurotoxic levels in the synaptic clefts. cDNAs encoding various mammalian glutamate transporter isoforms have been cloned and characterized. Grouping of protein products with similar functional characteristics has identified five subtypes of the excitatory amino acid transporter (EAAT) family: GLAST (EAAT1), GLT-1 (EAAT2), EAAC1 (EAAT3), EAAT4 and EAAT5. The expression of GLT-1, EAAT4, and EAAT5 is mainly restricted to the brain and retina, whereas the expression of GLAST and EAAC1 transcripts has also been reported in non-neuronal tissues, including the kidney, heart, lung, liver, placenta, and small intestine (2, 3, 7, 13, 14,17), thus suggesting the important roles of GLAST and EAAC1 in the uptake of nutrients and metabolites in non-neuronal organs.Ingested glutamate is extensively metabolized to provide whole-animal energy and support N homeo-

The primary cilium, a sensory apparatus, functions as both a chemical and mechanical sensor to receive environmental stimuli. The present study focused on the primary cilia in the epithelialmesenchymal interaction during tooth development. We examined the localization and direction of projection of primary cilia in the tooth germ and oral cavity of mice by immunohistochemical observation. Adenylyl cyclase 3 (ACIII)-immunolabeled cilia were visible in the inner/outer enamel epithelium of molars at the fetal stage and then conspicuously developed in the odontoblast layer postnatally. The primary cilia in ameloblasts and odontoblasts-shown by the double staining of acetylated tubulin and γ-tubulin-were regularly arranged from postnatal Day12, projecting apart from each other. The periodontal ligament possessed ACIII-positive cilia, which gathered on both sides of the dentin/cement and alveolar bone in postnatal days. In the oral cavity, numerous long primary cilia immunoreactive for ACIII were condensed at subepithelial stromal cells in the oral processes in fetuses, while postnatally a small number of short cilia were dispersed throughout the stroma of the oral cavity. These findings suggest that the primary cilia showing stage-and regionspecific morphology are involved in the epithelial-mesenchymal interaction during tooth development via mechano-and/or chemoreception for growth factors.

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Under a bilateral load, ridge height, clearance to the occlusal plane, and inclination of the ridge are considered to account for denture movement. To evaluate the effect of the ridge morphology on denture movement under a unilateral load, it is effective to determine the partitioned shape together with the height in general.

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We conclude that this method has sufficient measurement accuracy and reproducibility for the calculated movement of dentures.

This finite element study analyzed the displacement of maxillary canines as abutments for distal-extension removable partial dentures. Splinting of abutments was recommended in cases of reduced periodontal support or large and/or laterally directed occlusal force. Splinting six anterior teeth was recommended if these unfavorable conditions coincided with one another. AbstractPurpose: The purpose of this study was to investigate the relationship between the number of splinted teeth and the effect of splinting on the movement of canines as abutments for maxillary distal-extension removable partial dentures. Methods:A three-dimensional finite element method was used for the analysis. Abutments with normal bone height and with bone height lowered by 3 mm were prepared. The numbers of splinted teeth were two, three and six units. A load of 50 N or 200 N was applied in the vertical, buccal-oblique and lingualoblique directions at the node corresponding to the buccolingual center of the mesial marginal ridge of the left first molar. Different material properties of the mucosa and periodontal ligament were used depending on the amount of loading. The ligament was defined as an orthotropic material. Results:The results showed that horizontal displacement of the canine in the "two-unit splint" model was approximately one-third to one-half of that in the single abutment model. There was little difference in the horizontal displacement between the two-unit splint and "three-unit splint" models. In the "six-unit splint" model, the displacement was reduced to approximately half of that of the two-unit splint model. In all of the splinted models, the vertical displacement was reduced to approximately half of that of the single abutment model. Conclusion:In the cases of reduced periodontal support or large and/or laterally directed occlusal force, abutments should be splinted. In cases of a coincidence of these unfavorable conditions, splinting six anterior teeth was recommended.