Specific depletion of GGA2 causes cathepsin D missorting in HeLa cells.

Three mammalian GGAs (Golgi-localized, gamma-ear-containing, ARF-binding proteins), GGA1, 2, and 3 have been implicated in the sorting of mannose 6-phosphate receptor (MPR). To investigate the distinct roles of GGA2 in lysosomal enzyme transport, we established two stable cell lines that had a reduced expression of GGA2 by RNA interference. The expression levels of GGA2 were approximately 5% of the control levels, whereas those of non-targeted GGA1 and GGA3 were not apparently reduced.

Biomechanical analysis on platform switching: is there any biomechanical rationale?

Objectives: The purpose of this study was to examine the biomechanical advantages of platform switching using three-dimensional (3D) finite element models.

Material And Methods: 3D finite element models simulating an external hex implant (4 x 15 mm) and the surrounding bone were constructed. One model was the simulation of a 4 mm diameter abutment connection and the other was the simulation of a narrower 3.

Estimation of functional load direction to an implant using normal lines on the superstructure occlusal surface.

This study was designed to test the hypothesis that normal lines on the occlusal surface of a superstructure allow estimation of the functional load direction to an implant. Micro-occlusal surface data were obtained using a 3-dimensional laser scanner to identify the normal lines, and strains on the abutment surface were measured with strain gauges under static load using an in vitro model. Measurements were repeated following alterations of the occlusal surface cusp angle.

Anterior palatal mouthguard margin location and its effect on shock-absorbing capability.

The purpose of this study was to evaluate the influence of a mouthguard's (MGs) anterior palatal margin location on its shock absorbing capability. A simulation study was conducted on a maxillary phantom model with maxillary teeth, bone, and soft tissue. Miniature strain gauges were attached to the labial and palatal surfaces of the right central incisor as well as the bone surface on the palatal side.

In vitro differences of stress concentrations for internal and external hex implant-abutment connections: a short communication.

The aim of this study was to clarify the difference in the stress distribution patterns between implants with external-hex or internal-hex connection systems using in vitro models. Three 13 mm fixtures with external-hex and internal-hex connections were installed into an acrylic bone analogue. One piece abutments of 7 mm height was connected.

A method for fabricating an occlusal splint for a patient with limited mouth opening.

This article describes the fabrication of an occlusal splint for a patient with limited mouth opening due to temporomandibular disorder. A face-bow fork is used as a tray to obtain an accurate dual-arch impression and occlusal registration.

Efficacy of a posterior implant support for extra shortened dental arches: a biomechanical model analysis.

The purpose of this study was to test the efficacy of utilizing implants underneath distal free-end denture bases to establish a stable occlusal support for extreme shortened dental arches (ESDA). The authors constructed a two-dimensional finite element model of the ESDA where only lower anterior teeth remain. Posterior occlusal support was provided by a fixed partial denture with an osseointegrated implant (IFPD), fixed cantilever partial denture (CFPD), or a removable partial denture with or without an implant underneath (IRPD and RPD).

[Future directions of molecular bone cell biology].

Introduction of genetic approaches using knockout and/or transgenic mice has produced many pieces of information that can't be obtained by conventional cell biological studies and profoundly advanced our understanding of bone biology and metabolism. Here, the author will first briefly summarize the current findings in the recent bone research and subsequently attempt to predict future directions to which bone research is going to proceed with a special emphasis of osteoclast and osteoblast biology.

Studies on cytotoxic effect of nickel ions on three cultured fibroblasts.

Cytotoxicity of Ni ions on three fibroblasts such as L929, Balb/3T3 clone A31 and MC3T3-E1 were examined by cell count (CC) and Neutral Red assay (NR). Three cells were incubated for 6 days in 1 ml DME medium containing Ni ions which ranged from 0 to 2 mM/l. The results clarified that Ni ions had dose-dependent cytotoxicity.

Early-phase redistribution of the cation-independent mannose 6-phosphate receptor by U18666A treatment in HeLa cells.

It has been shown that the treatment with 3beta-[2-(diethylamino)ethoxy] androst-5-en-17-one (U18666A) causes the accumulation of cholesterol and the cation-independent mannose 6-phosphate receptor (CIMPR) in late endosomal/lysosomal compartments in BHK cells. The present study reports on a study of the effect of U18666A on CIMPR distribution in more detail in HeLa cells. When cells were treated with U18666A for 20 h, the intense perinuclear signal for CIMPR corresponding to the trans-Golgi network (TGN) disappeared and lamp1-negative punctate signals, scattered in the perinuclear region were detected.

Effect of ion-exchange treatment on mechanical properties of new dental ceramics.

Purpose: To examine whether the ion exchange strengthening can be achieved for several new ceramics such as glass ceramics or castable ceramics.

Methods: The ceramics selected for this study were three porcelains and three castable ceramics. 60 bend bars of the respective ceramics (1 x 5 x 10 mm) were fabricated according to the respective manufacturer's directions.

Activation of beta-catenin-LEF/TCF signal pathway in chondrocytes stimulates ectopic endochondral ossification.

Objective: Members of the Wnt signaling protein family are expressed during cartilage development and skeletogenesis, but their roles and mechanisms of action in those processes remain unclear. Recently, we found that beta-catenin-LEF/TCF-dependent Wnt signaling stimulates chondrocyte maturation and hypertrophy and extracellular matrix calcification in vitro, events normally associated with cartilage-to-bone transition during skeletogenesis. Thus, we tested here whether activation of this pathway promotes endochondral ossification.

Runx2 expression and action in chondrocytes are regulated by retinoid signaling and parathyroid hormone-related peptide (PTHrP).

Objective: Runx2 (also known as Cbfa1) is a transcription factor required for chondrocyte maturation and osteoblast differentiation. While there is information on the regulation of its expression during osteogenesis, much less is known about it during cartilage maturation. Here we asked whether Runx2 expression and function are affected by retinoic acid (RA) and parathyroid hormone-related peptide (PTHrP), which represent an important stimulator and inhibitor of chondrocyte maturation, respectively.

Fluoride, hydrogen ion and HEMA release from light-cured GIC restoratives.

Purpose: To quantitatively measure the amount of fluoride, hydroxy ion and hydroxyethyl methacrylate (HEMA) released from various light-cured restorative materials.

Materials And Methods: Three resin-modified glass-ionomer cements (RMGI): Photac-Fil Aplicap, Vitremer, and Fuji II LC and two polyacid-modified resin-based composites (compomer): Dyract and Variglass VLC were used in this study. Disc-shaped specimens were made as per manufacturer's recommendations and the surfaces were polished with a 600 grit abrasive paper.

The Wnt antagonist Frzb-1 regulates chondrocyte maturation and long bone development during limb skeletogenesis.

The Wnt antagonist Frzb-1 is expressed during limb skeletogenesis, but its roles in this complex multistep process are not fully understood. To address this issue, we determined Frzb-1 gene expression patterns during chick long bone development and carried out gain- and loss-of-function studies by misexpression of Frzb-1, Wnt-8 (a known Frzb-1 target), or different forms of the intracellular Wnt mediator LEF-1 in developing limbs and cultured chondrocytes. Frzb-1 expression was quite strong in mesenchymal prechondrogenic condensations and then characterized epiphyseal articular chondrocytes and prehypertrophic chondrocytes in growth plates.

Infection and pathogenesis of a murine strain of Escherichia coli with genetically introduced Shiga toxin type I operon in conventional mice.

The pathogenic response elicited by Shiga toxin type I (Stx1)-producing Escherichia coli was studied using an E. coli strain BME5 obtained from the natural flora of the mouse and used on three different strains of mice. The recombinant strain BME5/Stx1 was prepared by introducing the gene for Stx1.

Distribution of emm genotypes and superantigen genes of Streptococcus pyogenes isolated in Japan, 1994-9.

The purpose of this study was to examine characteristic profiles of Streptococcus pyogenes clinical isolates isolated in Japan during 1994-9. Genotyping of the M protein (emm typing) revealed that emm types 12 and 28 were the most common among 316 isolates. Most of the emm12 isolates were isolated from mucosa, while emm58 and emm89 were from skin.

Stress analysis of metal-free polymer crowns using the three-dimensional finite element method.

Purpose: The purpose of this study was to evaluate the stress distribution under various loading conditions within posterior metal-free crowns made of new composite materials.

Materials And Methods: A three-dimensional finite element model representing a mandibular first molar was constructed. Variations of the model had crowns of two types of composite, a glass ceramic, and porcelain fused to metal.

Dental status and satisfaction with oral function in a sample of community-dwelling elderly people in Japan.

The purpose of this study was to determine the influence of dental status on oral function and satisfaction among a group of independently living elderly persons in an urban area of Japan. The study sample consisted of participants of the Senior Citizens' College from 1995 to 1999. Their dental status and oral satisfaction were measured by a questionnaire.

Novel laminin-binding protein of Streptococcus pyogenes, Lbp, is involved in adhesion to epithelial cells.

The lbp gene, which encodes a laminin-binding protein (Lbp) of Streptococcus pyogenes, was found in all S. pyogenes M types. An Lbp-deficient mutant showed a significantly lower efficiency of adhesion to HEp-2 cells than did the wild-type strain.

Induction of instability of p34(cdc2) expression by treatment with cisplatin (CDDP) in mouse teratocarcinoma F9 cells.

p34(cdc2) is a protein kinase that plays an important role in the control of the cell cycle and regulation of activity of the tumor suppressor gene. Previously, we demonstrated that cisplatin (CDDP) induced growth suppression resulting in differentiation of teratocarcinoma F9 cells. In the present study, we investigated the mechanism of cell cycle retardation by CDDP in F9 cells, focusing on p34(cdc2).

The effects of polishing and bleaching on the colour of discoloured teeth in vivo.

Bleaching is an effective method for restoring the colour of discoloured vital teeth. Power bleaching, in particular, in which a bleaching solution containing 35% hydrogen peroxide is activated by a strong light source using a plasma arc, makes it possible to bleach teeth effectively in a short time. The purpose of this study was to determine how polishing or power bleaching the tooth surface affects tooth colour.

Facial asymmetry in patients with cervicobrachial pain and headache.

An increasing number of patients are visiting our hospital who have a chief complaint of neck and shoulder pain and/or headache but who do not have temporomandibular disorders (TMD). We carried out this study with a view to comparing the asymmetry of the facial skeleton or expression of such patients with those of healthy subjects. The incidence of such symptoms of patients and healthy subjects was examined by means of questionnaires.

Biochemical and genetic characterization of serologically untypable Streptococcus mutans strains isolated from patients with bacteremia.

Four out of 522 streptococcal isolates from the peripheral blood of patients with bacteremia exhibited typical properties of Streptococcus mutans in terms of sucrose-dependent adhesion, expression of glucosyltransferases, fermentation profiles of sugars, the presence of surface protein antigen, and DNA-DNA hybridization. Two strains were determined as serotype f and e by immunodiffusion, whereas the other two isolates did not react with the specific antiserum to S. mutans serotype c.

Participation of Cbfa1 in regulation of chondrocyte maturation.

Objective: Cbfa1 is a transcription factor, which is classified into the runt family. The mice lacking this gene display complete loss of bone formation, indicating that Cbfa1 is an essential factor for osteoblast differentiation. The Cbfa1-deficient mice also show an abnormality in cartilage development.