A Single Amino Acid Substitution in the Intervening Region of 129K Protein of Cucumber Green Mottle Mosaic Virus Resulted in Attenuated Symptoms

Cucumber green mottle mosaic virus (CGMMV), a member of the genus Tobamovirus, is a major threat to economically important cucurbit crops worldwide. An attenuated strain (SH33b) derived from a severe strain (SH) of CGMMV caused a reduction in the viral RNA accumulation and the attenuation of symptoms, and it has been successfully used to protect muskmelon plants against severe strains in Japan. In this study, we compared GFP-induced silencing suppression by the 129K protein and the methyltransferase domain plus intervening region (MTIR) of the 129K protein between the SH and SH33b strains, respectively. As a result, silencing suppression activity (SSA) in the GFP-silenced plants was inhibited efficiently by the MTIR and 129K protein of SH strain, and it coincided with drastically reduced accumulation of GFP-specific small interfering RNAs (siRNAs) but not by that of SH33b strain. Furthermore, analyses of siRNA binding capability (SBC) by the MTIR of 129K protein and 129K protein using electrophoretic mobility shift assay revealed that SBC was found with the MTIR and 129K protein of SH but not with that of SH33b, suggesting that a single amino acid mutation (E to G) in the MTIR is responsible for impaired SSA and SBC of SH33b. These data suggest that a single amino acid substitution in the intervening region of 129K protein of CGMMV resulted in attenuated symptoms by affecting RNA silencing suppression.

Down-regulated genes in mouse dental papillae and pulp

Important factors involved in odontogenesis in mouse dental papillae disappear between the pre- and post-natal stages of development. Therefore, we hypothesized that certain genes involved in odontogenesis in dental papillae were subject to pre-/post-natal down-regulation. Our goal was to identify, by microarray analysis, which genes were down-regulated. Dental papillae were isolated from embryonic 16-day-, 18-day- (E16, E18), and post-natal 3-day-old (P3) murine first mandibular molar germs and analyzed by microarray. The number of down-regulated genes was 2269 between E16 and E18, and 3130 between E18 and P3. Drastic down-regulation (fold change > 10.0) of Adamts4, Aldha1a2, and Lef1 was observed at both E16 and E18, and quantitative RT-PCR revealed a post-natal reduction in their expression (Adamts4, 1/3; Aldh1a2, 1/13; and Lef1, 1/37). These results suggest that down-regulation of these three genes is an important factor in normal odontogenesis in dental papillae.

Expression and function of laminin and integrins on adhesion/migration of primary culture cells derived from rat oral epithelium

BACKGROUND AND OBJECTIVE

It remains controversial whether or not the junctional epithelium cells that are directly attached to teeth migrate on the enamel surface, as those cells are able to adhere firmly to the enamel. The aim of this study was to investigate the expression patterns of laminin gamma(2), integrin beta(4) and integrin alpha(3), and to examine their potential function in cell migration.

MATERIAL AND METHODS

Oral epithelium cells obtained from Sprague-Dawley rats were established in primary culture. We employed a wound-healing assay to characterize the direction of cell extension at the start of cell migration, and observed different localizations of laminin and integrins using immunofluorescence. For functional analyses of integrins, we employed a phosphatidylinositol-3-kinase (PI3K) activator to promote integrin beta(4) function and used P1B5 to inhibit integrin alpha(3) function, and we analyzed the percentage of re-epithelialization as the migration function.

RESULTS

Marked accumulation of laminin gamma(2) was detected in the peripheral cytoplasm of cells adjacent to the wound area, as shown by the results of the migration assay. Integrin beta(4) was detected in the distal cell processes of actively migrating cells, while integrin alpha(3) was found in cell membranes of cells adjacent to the wound area. In the functional analyses, the percentage of re-epithelialization was significantly lower in the PI3K-activator group and in the P1B5-treated group (2.5% and 7.2%, respectively) than in the control group (39.0%) (p < 0.01).

CONCLUSION

The results suggest that laminin gamma(2) is secreted as a foothold for cell migration, that integrin beta(4) participates in cell adhesion and that integrin alpha(3) is involved in cell migration in the primary culture cells.

Effect of the dental adhesive, 4-META/MMA-TBB resin, on adhesion and keratinization of regenerating oral epithelium

BACKGROUND AND OBJECTIVE

The 4-META/MMA-TBB [4-(2-methacryloxyethyl)trimellitic anhydride/methyl methacrylate-tributylborane] resin is widely used as a dental adhesive. It has also been applied in the dressing of gingival wound surfaces following periodontal surgery. However, its effect on the regeneration and/or cell attachment of the oral epithelium remains to be clarified. To evaluate the effect of the resin applied as a wound dressing, we investigated expression of laminin 5, integrin beta(4) and cytokeratin 14 in regenerating oral epithelium treated with this resin following gingivectomy from the viewpoint of cell attachment and differentiation.

MATERIAL AND METHODS

The resin was applied to the entire wound surface in rats after gingival surgery, and regenerating epithelium was examined immediately and at 1, 3, 5, 7 and 14 days later. The resin was removed 2 weeks after application in some animals and tissue further examined at 1, 3, 5 and 7 days later.

RESULTS

Regenerating epithelium under the resin was not keratinized, but became keratinized immediately after removal of the resin. Laminin 5 and integrin beta(4) were immunolocalized in the basal lamina, the internal basal lamina, in marginal cells of the regenerating epithelium and at the resin-regenerating epithelium interface. Cytokeratin 14 localized in the regenerating epithelium underneath the resin, as well as in healthy and regenerated junctional epithelial cells.

CONCLUSION

These results suggest that this resin covers the wound surface and that the regenerating epithelium biologically adheres to the resin during the initial process of its regeneration.

Immunolocalization of laminin and integrin in regenerating junctional epithelium of mice after gingivectomy

BACKGROUND AND OBJECTIVE

The expression patterns of adhesive proteins and extracellular matrix proteins in regenerating gingival epithelium after gingivectomy are unknown. The aim of this study was to examine the expression of laminin 1, laminin gamma(2) (a specific component of laminin 5), integrin beta(4) and integrin alpha(3) in the regenerating gingival epithelium in order to understand the mechanism of wound healing during reconstitution of the sulcular environment.

MATERIAL AND METHODS

The palatal gingivae of the maxillary molars of Institute of Cancer Research mice were excised, and the regenerating tissues were examined 1, 3, 5, 7 and 14 days later. Fresh, non-fixed and non-decalcified frozen sections were prepared and stained using immunofluorescence.

RESULTS

At 1 day post-surgery, intense expression of laminin gamma(2), integrin beta(4) and integrin alpha(3) was distinct in the frontal margin of the regenerating oral epithelium. Laminin gamma(2) was diffusely detected on the root surface and in connective tissues beneath the regenerating oral epithelium at 3 and 5 days. At 7 days, laminin gamma(2) was intermittently recognizable in the internal basal lamina (IBL) close to tooth-facing cells, while laminin gamma(2), integrin beta(4) and integrin alpha(3) were observed in the IBL and in the external basal lamina (EBL) of the regenerating junctional epithelium at 14 days.

CONCLUSION

These results suggest that secretion of laminin 5 in the connective tissue may induce epithelial cell migration, and that binding of laminin 5 to integrin alpha(6)beta(4) and integrin alpha(3)beta(1) in the IBL may provoke cell adhesion and migration of cells facing the tooth on the enamel surface of the regenerating junctional epithelium.

Involvement of laminin and integrins in adhesion and migration of junctional epithelium cells

BACKGROUND AND OBJECTIVE

The junctional epithelium attaches to the enamel surface with hemidesmosomes (of which laminin-5 and integrin-alpha(6)beta(4) are the main components) in the internal basal lamina. Laminin-5 is also involved in cell motility with integrin-alpha(3)beta(1), although their functions have not yet been clarified.The purpose of this study was to determine the functions of those adhesive components between the tooth and the junctional epithelium during cell migration.Because an idea has been proposed that directly attached to tooth cells (DAT cells) may not contribute to cell migration, 5-bromo-2-deoxyuridine staining was performed to confirm cell migration.

MATERIAL AND METHODS

We investigated laminin-gamma(2) (contained only in laminin-5), integrin-beta(4) (involved in cell-extracellular matrix contact) and integrin-alpha(3) (inducing cell migration) in the junctional epithelium, oral gingival epithelium and gingival sulcus epithelium of 6-wk-old ICR mice using laser microdissection, quantitative real-time reverse transcription-polymerase chain reaction, immunofluorescence and 5-bromo-2-deoxyuridine staining.

RESULTS

Laminin and integrins were clearly immuno-localized in the basal lamina of all epithelium. Quantitative analysis of laminin and integrin mRNAs by laser microdissection showed that they were more highly expressed in DAT cells than in basal cells in the oral gingival epithelium. In particular, a 12-fold higher expression of laminin-5 was observed in the junctional epithelium compared with the oral gingival epithelium. 5-Bromo-2-deoxyuridine staining showed rapid coronal migration of DAT cells.

CONCLUSION

These results suggest that the abundant expression of laminin-5 and integrin-alpha(6)beta(4) is involved in the attachment of DAT cells to teeth by hemidesmosomes. Abundant expression of laminin-5 and integrin-alpha(3)beta(1) might assist in DAT cell migration, confirmed by 5-bromo-2-deoxyuridine staining during the turnover of junctional epithelium.

Design and analysis of a nonequilibrium cross-coupled network with a detectable similarity measure

In this paper, a nonequilibrium network which works as a dynamical associative memory is designed. The design is based on a new similarity measure between any stored pattern and a state of the network. Although conventional similarity measures, such as Hamming distance, direction cosine, and so on, are not detectable in a cross-coupled network, the similarity measure proposed in this paper is. The new similarity measure is employed in our design. The network should include the following properties in its output pattern sequence, so that the dynamics of cross-coupled network may be designed: 1) Stored patterns are frequently associated in the dynamical association. 2) The dynamical association is very robust against variation of distributed parameters. Property 1) is achieved by introducing the next two operation modes with inverse N-shaped function into the dynamics of the proposed network. 1) When the state of the network is close enough to a stored pattern at a time step, the state is forced to evolve at the next time step. 2) The state of the network converges to a stored one while it is not close to any stored patterns. By considering these two operation modes, the frequency of associating stored patterns is increased. The authors emphasize the property 2) which is very important for a silicon implementation of the proposed network. In the silicon implementation, parameters of the network must be represented by transistors, resistors, capacitors, and other electric components which exhibit variation in their characteristics. Thus the second property guarantees the easy silicon implementation of the nonequilibrium network proposed in this paper.

Claudin rather than occludin is essential for differentiation in rat incisor odontoblasts

Many morphological and developmental studies have demonstrated the characteristics of tight junctions (TJs) between odontoblasts. However, detailed localization of TJ-associated proteins in odontoblasts and their functions has not yet been clarified. To elucidate the relationship between the establishment of TJ structures and the differentiation of odontoblasts during early dentinogenesis, we studied the expression and localization of constituent proteins of TJs (claudin-1, occludin, ZO-1 and ZO-2) between odontoblasts in rat lower incisors using Western blotting, immunofluorescence and immunoelectron microscopy. When the expression of claudin-1 increases at the distal portion of mature odontoblasts, the TJs form complex networks of strands, and odontoblasts differentiated by developing distal membrane domains and by secreting specific molecules for mineralization. We conclude that the TJs of odontoblasts may play an important role in the differentiation of odontoblasts in rat lower incisors during early dentinogenesis.

Heat stress induces alkaline phosphatase activity and heat shock protein 25 expression in cultured pulp cells

AIM

To investigate the responses of cultured rat pulp cells to heat stress.

METHODOLOGY

Pulp cells were obtained from rat incisors and cultured at 37 degrees C. The cells were cultured at 42 degrees C for 30 min and then cultured at 37 degrees C again. Morphology, alkaline phosphatase (ALP) activity and expression of heat shock protein 25 (HSP25) were investigated at 0, 1, 3, 5, 7, 10 and 14 days following stimulation. As a control, the cells were maintained at 37 degrees C.

RESULTS

Although there were few cells of apoptosis immediately after heat stress, there were mitotic cells from day 1 after heat stress. ALP activity in the heat stress group significantly increased at days 7 and 14 compared with the control group (about 1.7-fold, P < 0.01, Friedman test). HSP25 expression increased in both groups, with HSP25 in the heat stress group being expressed earlier than in the control group, and nuclear localization of HSP25 was observed at days 0 and 1 in heat-stressed cells.

CONCLUSION

These results suggest that heat stress not only induces HSP25 but also enhances ALP activity in pulp cells.

Osteopontin as biomarker in early invasion by squamous cell carcinoma in tongue

BACKGROUND

Osteopontin (OPN) expression in squamous cell carcinoma (SCC) of the tongue has not been clearly elucidated.

METHODS

We selected 46 cases of tongue SCC and investigated the expression of OPN by immunohistochemical staining. The immunopositive reaction and score for each case were semiquantitatively evaluated.

RESULTS

Scores were significantly higher in carcinoma nests than in neighboring normal epithelium or epithelial dysplasia. The OPN was expressed clearly in the cytoplasm of carcinoma cells. In cases of early invasive carcinoma, in particular, expression of OPN showed a remarkable increase at the invasion front compared with the non-invaded regions. However, there was no significant correlation between expression of OPN in the primary tumor nest and lymphatic metastasis, recurrence, or survival rate.

CONCLUSION

This suggests that OPN is a useful biomarker of early invasion by SCC in tongue.

Morphology of Malassez's epithelial rest-like cells in the cementum: transmission electron microscopy, immunohistochemical, and TdT-mediated dUTP-biotin nick end labeling studies

BACKGROUND AND OBJECTIVE

It is known that epithelial islands are embedded in the cementum during tooth root formation, but details of this process remain unknown. The purpose of this study was to investigate the dynamic characteristics of Malassez's epithelial rest cells in the cementum during tooth root formation in pigs in vivo.

MATERIAL AND METHODS

The first molars of 6-mo-old pigs were used in this study. Specimens were decalcified before being embedded in paraffin. Paraffin sections were investigated using TdT-mediated dUTP-biotin nick end labeling (TUNEL), immunohistochemical, and ultrastructural techniques.

RESULTS

Malassez's epithelial rest cells were located close to the root surface at the apical one-third of the periodontal ligament, and epithelial clusters surrounded by distinct lamina cementia were sometimes observed in the cementum. TUNEL-positive cells were detected only in the cementum. Malassez's epithelial rest cells in the periodontal ligament were completely surrounded by basement membranes, but epithelial clusters in the cementum were only intermittently surrounded by such membranes. Cytokeratin-positive cells in the superstratum of the cementum were directly connected by cementocytes and by desmosome-like structures. However, organelles were scarce in the cytokeratin-positive cells in the substratum of the cementum, and the matrix of the cementum was deposited in the cells.

CONCLUSION

These results suggest that the majority of the fragmented Hertwig's root sheath remains in the periodontal ligament and that some cells, which are connected to cementoblasts, are embedded in the cementum and progress to apoptosis.

Responses of rat pulp cells to heat stress in vitro

Although heat stress can cause irritation in the dentin/pulp complex, little is known about the thermotolerance of pulp cells and their response to heat stress. We investigated cultured rat pulp cell responses to heat stress. Cells were subjected to a temperature of 42 degrees C for 30 minutes, and HSPs, alkaline phosphatase activity, and gap-junctional communication were determined at various time points. Although only low levels of HSP70 expression were detected before heat treatment, heat shock markedly induced HSP70 expression, with it gradually increasing at 1 hour after being heated. HSP25, however, showed no dramatic change. Gap junction protein connexin43 rapidly degraded after heat treatment, recovering to normal levels within the following 6 hours. Alkaline phosphatase activity decreased immediately after heat stress, recovering after 1 hour. These results indicate that dental pulp possesses protective factors, including HSPs, and that it can recover viability of intercellular communication and alkaline phosphatase activity after heat stress.

Konjak mosaic virus: the complete nucleotide sequence of the genomic RNA and its comparison with other potyviruses

Konjak mosaic virus (KoMV) belongs to the genus Potyvirus, family Potyviridae. The complete nucleotide sequence of KoMV F isolate (KoMV F) was determined. The genome is 9,544 nucleotides long excluding the 3' terminal poly A tail and encodes a typical potyviral 350-kDa polyprotein of 3,087 amino acids. Phylogenetic analysis using known potyvirus polyproteins shows that KoMV constitutes a branch with yam mosaic virus, close to another branch including Japanese yam mosaic virus, turnip mosaic virus, scallion mosaic virus and lettuce mosaic virus. The 3' terminal 1,842 nucleotides of a different isolate of KoMV, K-2, was also determined, covering the C-terminal 292 amino acids of the nuclear inclusion protein b (NIb), coat protein (CP), and the 3' untranslated region. The amino acid sequences of the KoMV F CP and the nucleotide sequences of the KoMV F 3' untranslated region showed 92.5 and 90.5% identity to the corresponding genes of K-2, 88.7-96.8 and 92.7-94.4% to those of Zantedeschia mosaic virus (ZaMV) isolates, 87.5-89.7% and 85.5-90.3% to those of Japanese hornwort mosaic virus (JHMV) isolates. These results showed that KoMV is a distinct potyvirus and that KoMV, ZaMV, and JHMV are members of the same potyvirus species. Considering that KoMV was the first of these to be described, ZaMV and JHMV may be considered isolates of KoMV.

Correlation between reduction of syndecan-1 expression and clinico-pathological parameters in squamous cell carcinoma of tongue

We examined expression of syndecan-1 in squamous cell carcinoma (SCC) of tongue using immunohistochemistry. Forty-three cases of SCC arising in lateral border of tongue were investigated. From the immunohistochemical staining pattern, the cases were divided into two groups based on expression of syndecan-1 at the supra-peripheral cells of the tumor nest: Group A, completely or mainly positive; Group B, sporadically positive or negative. Most poorly differentiated SCC cases were classified into Group B (81.8%). The number of Group B cases in T1-2 was different from that in T3-4. The number of cases where syndecan-1 expression was reduced was much greater in T3-4, and represented the majority of Group B (86.7%). More than 80% of Grade 4D cases were in Group B (83.3%) based on the Yamamoto-Kohama criteria. These results indicate that reduction of syndecan-1 correlates to histological grade, tumor size and mode of invasion in tongue SCC.

Reduction of osteocalcin expression in aged human dental pulp

AIM

To investigate the expression of osteocalcin mRNA in young and in aged human dental pulp tissue to determine the characteristics of osteocalcin expression.

METHODOLOGY

Human dental pulp tissues of the third molars were obtained from healthy young (17-23 years) and aged (>50 years) subjects, and total RNA was extracted. Osteocalcin mRNA expression was determined by RT-PCR and by quantitative real-time RT-PCR (QRT-PCR). The threshold cycle (Ct) value, which reflects the amount of PCR, was calculated and the difference between the value in young and aged pulp was statistically analysed.

RESULTS

Osteocalcin mRNA was detected in all samples of human dental pulp tissue homogenates by RT-PCR analysis. Osteocalcin mRNA was expressed in young adult dental pulp but was decreased in aged human dental pulp. QRT-PCR analysis also showed a reduced expression of osteocalcin mRNA in aged human pulp. Expression of osteocalcin in young human pulp was significantly higher (about sixfold) than in aged pulp (P<0.01, Mann-Whitney U-test).

CONCLUSION

Reduction of osteocalcin expression may be associated with the loss of viability in human dental pulp tissue, and may be a characteristic of aged human dental pulps.

Involvement of Aquaporin-5 Water Channel in Osmoregulation in Parotid Secretory Granules

Aquaporins (AQPs) are a family of channel proteins that allow water or very small solutes to pass, functioning in tissues where the rapid and regulated transport of fluid is necessary, such as the kidney, lung, and salivary glands. Aquaporin-5 (AQP5) has been demonstrated to localize on the luminal surface of the acinar cells of the salivary glands. In this paper, we investigated the expression and function of AQP5 in the secretory granules of the rat parotid gland. AQP5 was detected in the secretory granule membranes by immunoblot analysis. The immunoelectron microscopy experiments confirmed that AQP5 was to be found in the secretory granule membrane. Anti-AQP5 antibody evoked lysis of the secretory granules but anti-aquaporin-1 antibody did not and AQP1 was not detected in the secretory granule membranes by immunoblot analysis. When chloride ions were removed from the solution prepared for suspending secretory granules, the granule lysis induced by anti-AQP5 antibody was inhibited. Furthermore, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid, an anion channel blocker, blocked the anti-AQP5 antibody-induced secretory granule lysis. These results suggest that AQP5 is, expressed in the parotid gland secretory granule membrane and is involved in osmoregulation in the secretory granules.

Reduction of connexin 43 expression in aged human dental pulp

AIM

To investigate the expression of connexin 43 (CX43) mRNA in young and old human dental pulp tissues to determine the characteristics of CX43 expression.

METHODOLOGY

Samples were obtained from human dental pulp of healthy young (17-23 years) and aged (>50 years) subjects. CX43 expression was determined by RT-PCR and by quantitative real-time RT-PCR (QRT-PCR). The threshold cycle (Ct) value, which reflects the amount of PCR, was calculated and the difference between value in the young pulp and that in the aged pulp was statistically analysed.

RESULTS

RT-PCR analysis of human dental pulp tissue detected CX43 mRNA in all the samples. CX43 was abundantly expressed in young adult dental pulp, but expression of CX43 mRNA was dramatically decreased in aged human dental pulp. QRT-PCR analysis also showed the reduced expression of CX43 in aged pulp, and expression of CX43 in young pulp was significantly higher (about 10-fold, P < 0.01, Mann-Whitney U-test).

CONCLUSION

Reduction of CX43 expression may be associated with the loss of viability in human dental pulp, and is considered as one characteristic of aged pulp.

Proliferative activities of epithelial and connective tissue cells in the rat periodontal regeneration using argyrophilic nucleolar organizer regions staining

BACKGROUND AND OBJECTIVE

It is still an open question why long junctional epithelium can proliferate and occupies the root surface following periodontal surgery or experimentally produced periodontitis, and why the epithelium repopulated once on the root surface is replaced by the connective tissue. The aim of this study is to investigate the proliferative activity of the newly formed regenerative connective tissue and long junctional epithelium during wound healing by staining argyrophilic proteins of the nucleolar organizer regions (AgNORs).

METHODS

Regenerative connective tissue and long junctional epithelium were experimentally created by insertion of a rubber piece between maxillary molars of rats for 1 week. After removal of the rubber, AgNORs parameters including nuclear area (NA), AgNORs area (AA), AgNORs percentage nuclear area (APNA), AgNORs number (AN) and nuclear number (NN) in regenerative connective tissue and long junctional epithelium were measured and analyzed statistically.

RESULTS

APNA in long junctional epithelium after 1 and 4 weeks was over two times greater than that in the regenerative connective tissue. AA in long junctional epithelium was significantly higher than in regenerative connective tissue at 1 and at 4 weeks post-treatment. AN was higher in the central portion than at the root surface except at 20 weeks. APNA and AA decreased remarkably in long junctional epithelium at 12 weeks post-treatment (approximately half at 4 weeks), whereas in regenerative connective tissue, they did not change distinctly.

CONCLUSIONS

These results imply that long junctional epithelium cannot supply sufficient epithelial cells because of their significantly low rates of proliferation, consequently long junctional epithelium becomes shorter after 12 weeks, whereas the proliferative activity of regenerative connective tissue maintains the same level of proliferation, and ultimately long junctional epithelium is replaced by regenerative connective tissue.

Cell proliferation and tumour suppressor gene expression in iodine unstained area surrounding oral squamous cell carcinoma

The purpose of this study was to investigate the relationship between epithelial dysplasia unstained with iodine and the expression of proliferating cell nuclear antigen (PCNA) and/or tumour suppressor gene (p53) and the existence of glycogen. Thirty cases of squamous cell carcinomas arising from the buccal mucosa and floor of the mouth were examined. Iodine unstained areas were diagnosed histopathologically as mild, moderate or severe epithelial dysplasia. Normal oral mucosa stained with iodine was used as a control group. There was no histochemical difference in the distribution or ratio of PAS-positive cells between the control and the mild epithelial dysplasia groups, however PAS stained areas of the moderate and the severe dysplasia groups were significantly decreased. Ultrastructurally, glycogen granules were not recognized in the moderate or severe dysplastic epithelia. Immunoreactive ratios of PCNA and p53 in the moderate and severe dysplastic groups were significantly higher than those of the control and the mild dysplasia groups. The positive ratio of PCNA was higher than that of p53, although the immunostaining patterns of PCNA- and p53-positive cells were quite similar. These results suggest that mild dysplastic epithelia that are stained with iodine may be in the category of normal epithelia, whereas both moderate and severe dysplasia that are un-stained with iodine may be suspected of malignant lesions.

Effects of multigrooved surfaces on fibroblast behavior

Microgrooves have been investigated as substrates for the control of cell alignment. However, they are relatively too narrow and shallow for controlling the orientation of extracellular matrices (ECM) such as collagen. Multigrooves, a combination of microgrooves and macrogrooves, are expected to be able to control the orientation of both cells and ECM. This study investigated a method for fabricating multigrooves and evaluated fibroblast behavior on these novel surfaces. Multigrooved patterns were fabricated on a gold-alloy metal die, in which 90-degree V-shaped microgrooves with a 2-microm pitch were cut on trapezoidal macrogrooves. The macrogrooves had a 50- microm ridge width, a 50-microm wall width, a 50-microm bottom width, and a 25-microm depth. The grooves were made by an ultraprecision micromachine using a single crystal diamond. This metal die served as a template for making surface replicas from polystyrene. Microgrooved and smooth polystyrene replicas also were prepared as comparative substrates. Mouse fibroblast L929 cells were cultured in each type of replica substrate for 7 to 21 days. After these periods, the cells were fixed with 2.5% glutaraldehyde, treated with conventional methods, and, finally, observed by SEM. Confocal laser scanning microscopy was performed to investigate ECM formation. The multigrooved metal die exhibited the desired sharp configuration without defects. The dimensional values of the multigrooves on the polystyrene replicas were almost the same as the designed values. The fibroblasts on the multigrooved and microgrooved substrates were aligned parallel to the surface grooves after 7 days of incubation. In contrast to the microgrooved and flat surfaces, a dense extracellular matrix was produced along the multigrooves after 21 days of incubation. These results suggest that multigrooves can control the orientation of ECM as well as cells and thus enhance the production of ECM.

Oncocytic tumor in myoepithelioma arising from the grossopalatine gland

Oncocytoma or oncocytic change in salivary glands normally occurs in old patients and mostly in the parotid gland, but those arising from the grossopalatine gland in young patients are extremely rare. The present case shows that oncocytic ductal structures were observed in myoepithelioma, consisting of spindle, plasmacytoid or epithelioid cells. The oncocytic tumor contained large amounts of eosinophilic granular cytoplasm and small nuclei.

Oncocytic carcinoma arising in submandibular gland with immunohistochemical observations and review of the literature

We report a case of oncocytic carcinoma arising in submandibular gland. The tumour occurred in the left submandibular gland of an 82-year-old Japanese man. Histologically, the tumour was mostly composed of large cells with eosinophilic granules in the cytoplasm and they were arranged in the solid sheets, islands with duct-like structure and cords. The tumour cells had aggressively invaded muscles and perineural tissues, and cervical lymphatic metastasis was frequently observed. Histochemically, the tumour cells were strongly positive for phosphotungstic acid-hematoxylin (PTAH) stain, and we diagnosed this malignant tumour as oncocytic carcinoma. Immunohistochemically, the tumour cells reacted positively for cytokeratin 7, 8, 19, epithelial membrane antigen (EMA), alpha-1-antichymotrypsin and carcinoembryonic antigen (CEA), but negative for cytokeratin 13, 14, smooth muscle actin (HHF35) and S-100 protein (S-100). Tumour was diagnosed as oncocytic carcinoma in submandibular gland. Its characteristics are discussed in term of its histopathological and immunohistochemical features.

Effects of multigrooved surfaces on osteoblast-like cellsin vitro: Scanning electron microscopic observation and mRNA expression of osteopontin and osteocalcin

This study evaluated the behavior of osteoblast-like cells on multigrooved surfaces consisting of a combination of microgrooves and macrogrooves. A polystyrene substrate was fabricated with multigrooves with 90-degree, V-shaped microgrooves with a 2-microm pitch cut on trapezoidal macrogrooves, which had a 50-microm ridge width, a 50-microm wall width, a 50-microm bottom width, and 25-microm depth. Smooth polystyrene substrates were also prepared as controls. Rat bone marrow cells were cultured as osteoblast-like cells on the substrates for morphological evaluation using a scanning electron microscope, and for biochemical evaluation using the quantitative reverse transcriptase-polymerase chain reaction technique for osteopontin and osteocalcin mRNA expression. After 8 days of incubation, the osteoblast-like cells were aligned parallel to the surface grooves on the multigrooved substrates. After 16 days of incubation, a dense mineralized extracellular matrix (ECM) was produced along the multigrooves. The ECM on the multigrooved surface appeared oriented more in the direction of the grooves than on the smooth surface, and trapezoid-shaped macrogrooves of the ECM were cast upside down. Although there were not significant differences, the osteopontin and osteocalcin mRNA expressions of the osteoblast-like cells on the multigrooved surfaces tended to be higher than on smooth surfaces. These results suggest that multigrooves could be used to control the orientation of mineralized ECM as well as of cells, and also to enhance the production of mineralized ECM.

Bone response to calcium phosphate-coated and bisphosphonate-immobilized titanium implants

Thin calcium phosphate (Ca-P) coatings have been introduced to overcome the shortcomings of plasma-sprayed Ca-P coatings. In our previous experiments, thin Ca-P coatings also enabled the immobilization of bisphosphonate, which is a drug used to treat osteoporosis. The present study was designed to evaluate the bone response to titanium implants treated with a thin Ca-P coating and bisphosphonate. Forty cylindrical commercially pure titanium implants with a length of 7 mm and a diameter of 3 mm were used as test implant fixtures. Three groups of surface-treated implants were prepared: (1) blasted with titanium powder and etched with a solution of 10% HF + 5% HNO3 (control); (2) modified with 0.5-microm thick Ca-P coatings and rapid heat-treating, and (3) immobilized with bisphosphonate by immersion in pamidronate disodium solution (10(-2) M) for 24 h at 37 degrees C. These surface-treated implants were inserted into edentulous areas in the mandibular molar region of five beagle dogs. After implantation periods of 4 and 12 weeks, the bone implant interface was evaluated histologically and histomorphometrically. All measurements were statistically evaluated using a one-way ANOVA and Fisher PLSD test for multiple comparisons among the means. Four weeks after the implantation, higher percentage of bone contact was found around the thin Ca-P-coated implants compared to that of the control group. The highest percentage of bone contact was found around the bisphosphonate-immobilized implants after 12 weeks of implantation. These data suggest that a thin coating of calcium phosphate followed by bisphosphonate-immobilization is effective in the promotion of osteogenesis on surfaces of dental implants.

Cell proliferation and cell death in periodontal ligaments during orthodontic tooth movement

The purpose of this study was to investigate cellular responses of periodontal ligaments during tooth movement. Twenty-eight male Sprague-Dawley rats, weighing 200-250 g each, were used. To create the orthodontic force, elastic rubber blocks (0.65 mm thick) were inserted between the maxillary first and second molars on both sides. On days 3, 7, 10, 14, 21 and 28 after rubber block insertion, histopathological changes in both the tension and the pressure sides were examined by immunohistochemistry using proliferating cell nuclear antigen (PCNA) and by the TUNEL method. The ratios of PCNA-positive cells on the tension side 3 and 7 days after rubber block insertion were higher than those on the pressure side. The ratios of PCNA-positive cells on the tension side were highest at day 3 after insertion and then decreased during the remainder of the experimental period. On the pressure side, the ratios of PCNA-positive cells increased up to day 10 post insertion, then decreased from 14 to 28 days. The ratios of TUNEL-positive cells on both the tension and the pressure sides increased throughout the entire experimental period. These results indicate that the periodontal ligaments on the tension side are able to respond more promptly to orthodontic forces than those on the pressure side. The data also suggest that the ratios of cell proliferation and of cell death are closely related to the regeneration and reconstruction of periodontal ligaments which reflect the orthodontic force.

Spontaneous onset of torsade de pointes in long-QT syndrome and the role of sympathovagal imbalance

The net effects of sympathetic and vagal activity on the QT interval and the mode of spontaneous onset of torsade de pointes (TdP) are still unclear in long-QT syndrome. Two patients with long-QT syndrome had syncope while undergoing Holter ECG investigation. The spontaneous onset of TdP in these patients was analyzed with respect to the relation between the RR and QT intervals. Both patients were high-school students (16- and 17-year-old boys) who had been diagnosed as long-QT syndrome and followed up without medical treatment because they had had neither a history of syncope nor arrhythmia induction by treadmill exercise tests. The first episode of syncope in both patients occurred during ordinary daily life and was not related to exercise or psychological stress. The dynamic changes between the RR and QT intervals associated with the spontaneous onset of TdP were analyzed by Holter ECG. Both patients showed sinus tachycardia followed by abrupt sinus bradycardia immediately before the onset of TdP. The enhanced rate of the adaptive response of the QT interval that occurred during the deceleration of the heart rate preceded the onset of TdP. These observations suggest that the complex situation that follows sympathovagal imbalance may have an important role in the dynamic change in the QT interval and initiation of TdP in patients with long-QT syndrome.

Characteristics of newly formed bone during guided bone regeneration: observations by immunohistochemistry and confocal laser scanning microscopy

The purpose of this study was to investigate the characteristics of new bone formation during guided bone regeneration (GBR) using immunohistochemistry and confocal laser scanning microscopy. e-PTFE membranes were applied to defects created in the tibiae of rats, and some animals were sacrificed 6, 8, or 10 days later. Serial paraffin sections were cut, stained with H-E, and examined to analyze the ratio of new bone formation. Immunohistochemical staining with a monoclonal antibody specific for PCNA was used to evaluate the proliferating activity. In other experimental rats, calcein was injected at 6, 8, and 10 days after the surgery, and the animals were sacrificed 48 hr after injection. Their tibiae were removed, and Villanueva bone staining was performed before observation using confocal laser scanning microscopy to investigate the mineralization of new bones. The bone occupation ratio increased day by day, but the experimental groups had significantly higher ratios than control groups (without membrane) at each of the time periods. However, PCNA positive cells decreased over time in all groups, and there were no significant differences among the groups. Mineralization occurred more rapidly in the experimental groups than in the control groups. These results suggest that GBR accelerates the migration of osteogenic cells, the formation of new bone, and mineralization in the defect created by the e-PTFE membrane.

Immunohistochemical localization of amelogenin in human odontogenic tumors, using a polyclonal antibody against bovine amelogenin

In the present study, we investigated the localization of amelogenin in odontogenic tumors, using an anti-amelogenin polyclonal antibody. In order to make the antibody, antisera against an amelogenin fraction obtained from the enamel matrix of unerupted bovine tooth was raised in rabbits. By Western blot analysis, a main band of 25 kDa and six minor bands (6.8, 12, 18, 20, 23, and 27 kDa) were detected under nonreducing conditions. Immunoreactivity for the amelogenin was observed in ameloblasts and in the immature enamel matrix of 4-day-old rats. In odontogenic tumors, positive reactions for amelogenin were localized in limited areas in adenomatoid odontogenic tumor, calcifying odontogenic cyst, primary intraosseous carcinoma and odontoma. The strongest immunoreactions were shown in enamel matrices in odontomas. Small mineralized foci in epithelial nests showed positive reactions, and a few reactions were observed in epithelium adjacent to the mineralized foci. In calcifying odontogenic cysts, some ghost cells in the lining epithelium were strongly stained. The results indicate that the present antibody for amelogenin is useful for the determination of odontogenic tumors, especially in those in which small mineralized foci are present in the epithelial nests.

The in vitro and in vivo influence of 4-META/MMA-TBB resin components on dental pulp tissues

The purpose of this study was to qualitate the penetration of the major components of 4-META/MMA-TBB adhesive resin (4-META resin) and to characterize their influence on the in vitro and in vivo wound healing of dental pulp tissues. Fresh 4-META resin was applied to rabbit mesentery; its components penetrated the mesentery to form three of layers, depending on the amounts of monomer components in the tissue. The superficial layer was a soft-tissue hybrid layer (STHL), the intermediate layer contained small particles of polymerized 4-META resin, while the deepest layer contained unpolymerized monomer components including MMA and butanol, which were detected by gas chromatography (GC). To characterize the in vivo effects of the deepest layer, we immersed the pulp tissue in MMA or in 5% 4-META/MMA and autotransplanted it to placement beneath a rabbit kidney capsule. The MMA-immersed pulp was positive for osteocalcin and presented osteodentin formation at 7 days, as did the untreated control pulp tissue. In contrast, the 5% 4-META/MMA-immersed pulp collapsed into the cell-deficient fibrous connective tissue, with slight calcification by 7 days and less osteodentin formation at 14 days. Analysis of these data suggests that MMA does not inhibit osteogenic activity of pulp tissue, while 5% 4-META/MMA does inhibit osteogenic activity to some extent.

Successful treatment with concurrent chemoradiotherapy followed by surgery for a patient with thymic adenocarcinoma

Most neoplasms arising from the thymic epithelium are considered to be 'thymomas', which are composed of cytologically benign, neoplastic epithelial cells and nonneoplastic lymphocytes. In contrast, thymic epithelial neoplasms displaying cytologically malignant features have recently been classified as thymic carcinomas of various types of histology. However, primary thymic adenocarcinoma is extremely rare and only four cases of it have been reported in the literature. We report a rare case of primary thymic adenocarcinoma of 4-year complete remission with concurrent chemoradiotherapy followed by surgery. A 61-year-old Japanese man was referred to us complaining of facial edema and general fatigue. Computed tomography scans revealed a huge mass in the anterior mediastinum obstructing the superior vena cava. He was diagnosed with thymic adenocarcinoma on needle biopsy. He was treated with induction chemoradiotherapy consisting of cisplatin, 5-FU and concurrent thoracic radiation, which yielded a partial response. He then underwent surgical resection of the remaining mass. However, pathologic examination of the resected mass revealed no malignant cells. The patient is doing well without symptoms or signs of relapse 53 months after diagnosis.

Expression and localization of connexin 43 in rat incisor odontoblasts

We have examined the expression and localization of connexin 43 (CX43) in rat incisor odontoblasts using reverse transcriptase polymerase chain reaction, in situ hybridization and immunohistochemistry. The CX43 gene was expressed in odontoblasts, and levels of gene expression increased throughout the course of development. In contrast, CX43 was down-regulated at an incisal segment. In situ hybridization analysis showed no positive signal for CX43 RNA in the cytoplasm of differentiating dental papilla cells, but faint positive signals for CX43 RNA were observed in early pre-odontoblasts. Those signals were more intense in young and in old odontoblasts, but were less in short odontoblasts. CX43 could not be detected in differentiating dental papilla cells or in early pre-odontoblasts by immunohistochemical localization, but a positive reaction was found in the late pre-odontoblast stage where predentin had been produced. The positivity gradually increased during odontoblast maturation, and was highest in the layer of old odontoblasts. These results indicate that odontoblasts that secrete actively dentin matrix components are tightly in contact with each other by gap junctions as suggested by the intense CX43.

A case of an ameloblastic fibro-odontoma arising from a calcifying odontogenic cyst

This case report describes an ameloblastic fibro-odontoma arising from a calcifying odontogenic cyst (COC) in the mandible of a twenty-three-year old male. The patient was referred to the Department of Oral Surgery, Tokyo Dental College, on March 30th, 2000, complaining of a painful swelling, which had appeared three weeks earlier on his left mandibular molar region. In a pathological view, the lesion was a round cyst the size of a chicken-egg, dark red in color, and surrounded by a thick membrane. The cyst had an epithelium of varying thickness which included many ghost cells and an enamel-like structure on the inside, and a thick wall of connective tissue with an ameloblastic fibro-odontoma on the outside. Enamel organ-like epithelial islands were structured radially in the form of strands with immature dentin. Cytokeratin 19 was strongly immunoreactive in the epithelium of the lesion; osteopontin and osteocalcin reacted in the mesenchymal cells and weakly in the epithelial element of this tumor.

Tight junctions in the rat parotid gland

The aim of this study was to elucidate the distribution and morphological changes of tight junctions during secretion in parotid gland acinar cells. Localization of tight junction-associated polypeptide ZO-1, and of tight junction transmembrane protein Occludin, was examined in rat parotid gland by immunofluorescence and immunogold labelling of ultrathin sections. Adult male Sprague-Dawley rats were intraperitoneally injected with IPR and, after 10 and 30 minutes, parotid glands were extirpated. In control specimens, positive immunoreaction for ZO-1 and Occludin was observed on the adluminal side between adjacent cells in the form of narrow elongated profiles corresponding to intercellular canaliculi. After IPR injection, canaliculi became dilated and fluorescence was no longer seen as a continuous line but appeared as an aggregation of separate bright particles. ZO-1 was more widely distributed and was recognized in other areas of the cytoplasm as well. Concurrently, omega-shaped concavities, marked by actin fluorescence, appeared along the intercellular canaliculi. We concluded that, during exocytosis, the selective permeability barrier to the paracellular pathway, based on tight junctions, becomes more leaky, owing to segregation of Occludin caused by intracellular ZO-1 distributional changes associated with actin filaments.

Connexins in salivary glands

Connexins (Cxs) make up a family of gap junction structural proteins that form hexameric assemblies in the plasma membranes of adjacent cells that interact to form intercellular channels. It has been demonstrated that many kinds of CXs are differentially expressed in a variety of tissues; however, there have been only a few studies of CX expression in rat salivary glands. The co-localization of CX26 and 32 was examined in the parotid glands. Double immunofluorescence revealed that CX26 and 32 were present in the same gap junction. Double immuno-electron microscopy showed co-localization of both CX26 and 32 on the same gap junctional membranes between acinar cells. These results suggest that CX26 and 32 may participate in regulation of secretory function and permeability of acinar cells in the rat parotid glands.

The Helper Component-Proteinase of Sweet potato feathery mottle virus Facilitates Systemic Spread of Potato virus X in Ipomoea nil

ABSTRACT When Ipomoea nil was coinfected with Sweet potato feathery mottle virus (SPFMV), a member of the genus Potyvirus, and Potato virus X (PVX) typical symptoms caused by PVX were observed on those by SPFMV on the first upper true leaves at 14 days postinoculation (dpi). On the other hand, no PVX-induced symptoms were observed on the first upper true leaves at 14 dpi when plants were infected with PVX alone. In the case of coinfection with PVX and SPFMV, PVX RNA was detected not only in the inoculated cotyledonary leaves but also in the first upper true leaves at 14 dpi. In the case of single infection with PVX, PVX RNA was detected in the inoculated cotyledonary leaves but not in the first upper true leaves at 14 dpi. The accumulation of SPFMV remained unchanged, regardless of whether the inoculum consisted of SPFMV alone or a mixture of SPFMV and PVX. Although recombinant PVX engineered to express the helper component-proteinase (HC-Pro) of SPFMV (PVX.HC) enhanced symptoms severity in Nicotiana benthamiana, PVX.HC induced the synergism characterized by an enhanced viral movement in Ipomoea nil. Immunofluorescence microscopic examination revealed that the HC-Pro was present in phloem of SPFMV-infected I. nil. These results suggest that SPFMV HC-Pro acts as an enhancer of long distance movement for PVX in I. nil.

Immunohistochemical study of dental pulp applied with 4-META/MMA-TBB adhesive resin after pulpotomy

The purpose of this study was to investigate nerve regeneration and proliferative activity in amputated pulp tissue after the application of 4-META/MMA-TBB adhesive resin (4-META resin). Calcium hydroxide was used as a control material. At 3 days, fibroblast-like cells were positive for proliferating cell nuclear antigen (PCNA) in both 4-META resin- and calcium hydroxide-treated groups and were located mainly within 0.5 mm from the cut surface. Only a few fragmented neurofilament protein (NFP)-positive nerve fibers were observed in this area. At 7 and 14 days, the number of PCNA-positive cells had gradually decreased and regenerated NFP-positive nerve fibers were observed close to the cut surface of the pulp in both groups. At 21 days in the experimental group, several PCNA-positive cells were still found in the area 0.5 mm from the cut surface, and NFP-positive nerve fibers were detected about 0.15-;0.2 mm from the cut surface. In contrast, a dentin bridge was produced under the necrotic layer at 21 days in the control group. PCNA-positive cells were not found underneath the dentin bridge, but NFP-positive nerve fibers had regenerated close to it. These results suggest that although cell differentiation and nerve regeneration are delayed, wound healing occurred even after the application of 4-META resin to exposed pulp surface the same as calcium hydroxide application.

Ultrastructural and immunoelectron microscopic studies of the peri-implant epithelium-implant (Ti-6Al-4V) interface of rat maxilla

BACKGROUND

The role played by the internal basal lamina (IBL) and hemidesmosomes between an implant and the peri-implant epithelium (PIE) in the adherence of the epithelium to the implant is controversial. This study used rat maxilla implantation models to clarify the ultrastructure of the PIE-implant interface.

METHODS

Ti-6Al-4V implants were inserted either immediately or 2 weeks after the extraction of the upper left first molar of 6- or 4-week-old rats, respectively. The junctional epithelium (JE) of the upper right molars in the same animals was used as a control. Four weeks after implantation, the animals were sacrificed to prepare specimens for light and immunoelectron microscopy.

RESULTS

Under light microscopy, the PIE appeared to attach to the implant surface. Ultrastructurally, IBL, consisting of the lamina densa and lamina lucida, and hemidesmosomes were formed only in the lower region, and rarely in the middle region, of the PIE-implant interface. In control teeth, the IBL and hemidesmosomes formed throughout the dento-JE interface. Laminin-1 was found in the IBL and also in the vesicles and vacuoles of the PIE and JE cells. Statistical analysis showed that there was also a significant difference in the amount of IBL between the PIE-implant and dento-JE interfaces.

CONCLUSIONS

PIE attached to the implant via hemidesmosomes and IBL in the lower region of the PIE-implant interface. Although PIE cells may secrete laminin-1, which contributes to epidermal cell adhesion, the PIE which attaches to implants only in the lower region of the interface is considered to be the poorly adhered epithelium.