Biological apatite (BAp) crystallite c-axis alignment is known to be a factor in the mechanical function of bone. However, reports are lacking on mechanical properties in the alveolar area and base of the mandible area of the human mandible, which has complex occlusal force. In addition, there are many unclear mechanical properties concerning the relationship with BAp crystallite alignment. We therefore aimed to elucidate the relationship between BAp crystallite alignment and Young’s modulus in the alveolar area and base of the mandible area in human mandible cortical bone. The effect of occlusal force on bone quality at first molar in the mandible was also discussed.
Mandibular specimens including teeth were obtained from 6 Japanese adult cadavers (mean age: 63.0 ± 12.1 years) housed at the Department of Anatomy, Tokyo Dental College. A microbeam X-ray diffraction system was used to determine BAp crystallite alignment along the mesiodistal direction (longitudinal axis) in each specimen. Young’s modulus was also measured at the same sites along the mesiodistal direction by nanoindentation and its relationship with BAp crystallite alignment examined.
BAp crystallite alignment at first molar in human mandible cortical bone was low in the alveolar part but high in the base of mandible. The same tendency was observed for Young’s modulus at the same sites. Furthermore, a positive correlation was recognized between BAp crystallite alignment and Young’s modulus (p < 0.01).
The present results showed a close relationship between BAp crystallite alignment and Young’s modulus, suggesting the importance of determining BAp crystallite alignment when evaluating bone strength. Determination of BAp crystallite alignment at first molar in human mandible may be useful in determining the effects of occlusal force.

View full abstract

Recent research on osteoporosis has led to a number of advances in our understanding of its pathophysiology and treatment. However, much is still unknown, and a consensus is yet to be reached on how osteoporosis affects the jaw. With this in mind, the present study sought to identify changes over time in the mandibular cancellous bone of senile osteoporotic mice by assessing the trabecular structure in their mandible and tibia. The senescence-accelerated mouse strain P6 (SAMP6) (n = 5) was used as the experimental model, whereas the senescence-accelerated mouse strain R1 (SAMR1) served as control (n = 5). All mice were aged 16 weeks. Bone morphometry was performed by taking a series of micro-computed tomography (micro-CT) scans of the same animal at different time points. As a result, the morphometric parameters of bone volume fraction (BV/TV), trabecular thickness (Tb.Th) and trabecular number (Tb.N) in the tibias of the SAMP6 mice were significantly lower than those of the SAMR1 mice. Conversely, there were no consistent differences in these parameters in the jaw bones of SAMP6 or SAMR1 mice. These findings may suggest that relevant load-bearing teeth protect the alveolar bone structure from the degenerative effects of osteoporosis.

View full abstract

The tensile fracture characteristics of AZ31B magnesium alloy with Si-contained coating was studied using a constant extension rate tensile in dynamic Hank’s solution. The study showed that the fracture characteristics of the uncoated and coated AZ31B magnesium were different. The uncoated alloy exhibited predominant intergranular cracks while the coated revealed mixed intergranular and transgranular mode failure. The mechanical integrity of the coated AZ31B magnesium alloy was improved compared with the uncoated.

View full abstract

The purpose of this study was to assess the response of osteoblasts (MC3T3-E1) and fibroblasts (L929) toward an extremely low magnetic field (ELMF) exposure. The strength and frequency of the field were set to 0.4 T and 0.17 Hz, respectively. The cells were exposed to semi-confluent culture plates for 6 hours. Cell proliferation was assessed on days 1, 3, 7 and 10 after the ELMF exposure. To evaluate osteoblastic differentiation, we measured alkaline phosphatase (ALP) activities of MC3T3-E1 cells at 3, 7 and 10 days after the exposure. The effects on mineralized nodule formation was evaluated by Alizarin Red S staining at 21 day culture. The results revealed that proliferation of the MC3T3-E1 cells was stimulated 3 days after ELMF exposure, whereas that of L929 cells was not stimulated in the day 3 culture. This stimulation was not observed at 7 or 10 days in either cell. ALP activities of the MC3T3-E1 cells were significantly increased 7 and 10 days after the exposure, and calcified nodule formation was also promoted as compared to the non exposed control culture on day 21. These results suggest that osteoblasts demonstrate specific response to magnetic fields, and that bone formation can be accelerated through the stimulation of osteoblasts by ELMF.

View full abstract

The structure and function of the amelogenin gene on a tooth germs in the frog Xenopus tropicalis, were examined. Using PCR, we observed an intensive band of amelogenin in maxillas with teeth but not in the toothless mandibles, and in situ hybridization revealed the restricted expression of amelogenin only in secreting ameloblasts in a tooth germs. Sequence analyses indicated that two types of amelogenin mRNA were alternatively spliced and derived from a single gene. They are referred to here as amelogenin mRNA-A and -B. In unique 5’-UTR, mRNA-A has a long exon 1, which is much longer than the same exon in other animals’ amelogenin, and both mRNA-A and -B possesses new exons, referred to here as exon 2a and 2b. The following protein coding region was divided into five exons, as in the case of another frog, Xenopus laevis, whose amelogenin sequence was closest to X. tropicalis, and the amelogenin of X. tropicalis may play a role in enamel formation, as in other animals. A pair of amelogenin mRNAs of X. tropicalis have the most primitive sequence among known mRNAs and, in particular, the extremely long exon 1, and the newly found exons 2a and 2b , may be key in exploring the archetype of amelogenin mRNA.

View full abstract

Rheumatoid arthritis (RA), one of the most common articular diseases, is characterized by chronic inflammation, hyperproliferation of synovial cells, and bone destruction. CD81, which belongs to a family of cell-surface proteins (tetraspanin), is known to be up-regulated in RA synoviocytes. Recently, we showed the therapeutic effect of using small interfering RNA in targeting CD81 (CD81 siRNA) for RA. Here we show how tumor necrosis factor-alpha (TNF-α) can induce the expression of synoviolin, which is decreased by the addition of CD81 siRNA in SW982 cells. In addition, CD81 siRNA decreases the expression of TNF-α in SW982 cells, suggesting that TNF-α stimulates the expression of synoviolin via CD81. Furthermore, knock down of CD81 by the addition of CD81 siRNA decreases the expression of TNF-α, and TNF-α-induces expression of synoviolin in direct and indirect ways. These results in SW982 cells might explain the therapeutic effect of CD81 siRNA in animal models.

View full abstract

We conducted an in vivo study to clarify the mechanics of the mandibular bone and condyles in pediatric patients with mandibular functional deviation. We experimentally caused lateral displacement of the mandible in 4-week-old rats by attaching a plate to the teeth for 4 (short-term group: ST group) or 12 weeks (long-term group: LT group), and immunohistochemically investigated the pattern of appearance of matrix metalloproteinase-1 (MMP-1), vascular endothelial growth factor (VEGF), and connective tissue growth factor (CTGF) to investigate the changes in the cartilage matrix constitution during the recovery of the condylar morphology. Furthermore, the morphology was observed using micro (μ) -CT.
After plate removal, the MMP-1 expression significantly decreased in the both groups. Furthermore the expressions of VEGF and CTGF were increased in the ST group compared to those observed in the LT group. In terms of the morphometry, mandibular asymmetry and deformity of the condyle were noted immediately after removal in the both groups. The mandibular morphology markedly recovered in the ST group compared to that in the LT group. This indicates that correction of occlusal abnormalities during an early stage leads to recovery of the normal mandibular configuration.

View full abstract

The purpose of the present study is to investigate the pathological mechanism of cervical vertigo by studying the nervous connections between cervical spinal ganglia and cervical sympathetic ganglia. Seventy New Zealand rabbits were randomly divided into a superior cervical spine group (C2 and C3), an inferior cervical spine group (C4 through C6), and corresponding control groups. The cervical ganglia of the rabbits in the experimental groups were injected with 4% fluorogold solution, whereas those in the control groups were injected with physiological saline. The rabbits were killed after four days. The sympathetic ganglia were cut, preserved via cryosection, and observed under a microscope. Fluorescence was observed in the ipsilateral superior cervical sympathetic ganglia of the specimens in C2 and C3 into which dye was injected, but not in the inferior cervical ganglia or contralateral superior ganglia. Fluorescence was also observed in the ipsilateral inferior cervical sympathetic ganglia in the C5 and C6 groups, but not in the contralateral inferior cervical sympathetic ganglia or superior ganglia of either side. Injection of fluorogold at C4 produced ipsilateral fluorescence in both the superior and inferior cervical sympathetic ganglia. Nerve fiber connections are present between the cervical spinal ganglia and cervical sympathetic ganglia. These connections are arranged in a segmental distribution.

View full abstract

It has been suggested that dysphagia caused by excision of carcinoma of the tongue may be affected by the hypofunction of the surrounding muscle tissues, as well as by tissue defects. However, there have been no reports concerning how muscle fiber characteristics change in the regions surrounding the lesion after excision of the carcinoma. In this study, we investigated myosin heavy chain (MyHC) isoforms at genetic levels in order to demonstrate the muscle fiber characteristics of the muscle tissues surrounding lingual carcinoma (the experimental group). High mobility group box 1 (HMGB1) was used as a marker to examine whether tongue cancer actually developed. MyHC-2a expression was high in the experimental group. Thus, the marked changes of muscle fiber characteristics, as seen in this study, were considered to be a biological reaction to changing muscle characteristics for regenerating or maintaining normal muscle tissues against the muscle atrophy caused by carcinoma.

View full abstract

We evaluated the ability of platelet-derived growth factor (PDGF) to promote bone augmentation beyond the skeletal envelope in rat calvarium. The calvaria of 14 rats were exposed and two plastic caps were placed with 0.03% or 0.01% PDGF with a collagen sponge (ACS) or ACS alone in the calvarium. Micro-CT and histological sections were used to obtain amount of bone augmentation within the plastic caps. Bone volume (BV) was calculated using BV-measuring software. The BV and amount of bone augmentation were significantly increased in the PDGF groups compared to the control groups after 4 weeks. However, there was no significant difference between the 0.03% and 0.01% PDGF groups. These results indicate that 0.03% and 0.01% PDGF in ACS enhance bone formation beyond the skeletal envelope in rat calvarium.

View full abstract

Bone marrow mesenchymal stem cells (BMMSCs) could be induced to osteoblasts, which were considered as the seed cells source for organizational engineering. Moreover, it has been demonstrated that Static Magnetic Field (SMF) can stimulate osteoblasts differentiation, but SMF stimulation acting on BMMSCs remained unknown results. The aim of this study is to investigate the effect of SMF acting on rat BMMSCs during osteogenic differentiation in vitro. The experimental BMMSCs were divided into 2 groups, which were experiment group and control group, and both of them were induced by differentiate medium. Experiment group was exposed to SMF at 200 mT 24h/day during osteogenesis. Contrarily, control group was not exposed to SMF during osteogenesis. Results showed that SMF exposure significantly increased the cell proliferation rate, alkaline phosphatase (ALP) activity, as well as the expression of osteogenesis-related proteins. Besides, matrix mineralization was significantly more visible in experiment group than that in control group on the 7th day of the experimentation. In summary, SMF exposure could significantly enhance osteogenic differentiation and mineralization of rat BMMSCs.

View full abstract

Amelogenin is an enamel matrix protein also expressed in periodontal tissues. Recent studies suggest that lysosome-associated membrane proteins (LAMPs) can bind cell surface amelogenin and act as signaling receptors for amelogenin in periodontal ligament (PDL) cells and cementoblasts in vitro. However, whether amelogenin and LAMPs are involved in the development of periodontal tissues is unclear. To address this issue, we used immunohistochemistry to profile LAMPs and amelogenin expression during periodontal tissue development. Paraffin sections from mice at embryonic day 15 (E15) and 1, 2, and 4 weeks were made, and serial sections at each age were stained with hematoxylin-eosin, followed by immunostaining with antiamelogenin, LAMP-1, and LAMP-3. At E15, dental follicle cells, which are the source of periodontal tissues, were amelogenin-positive and weakly positive for LAMP-1 and LAMP-3. At 1 week, dental follicle cells were immunopositive for amelogenin and LAMP-1 but weakly positive for LAMP-3. At 2 weeks, PDL cells were positive for amelogenin and LAMP-1 but negative for LAMP-3. At 4 weeks, PDL cells were immunopositive for both amelogenin and LAMP-1. These results suggest that LAMP-1 is expressed in both the dental follicle and PDL, and that LAMP-1 and LAMP-3 have temporally distinct roles as signaling receptors for amelogenin.

View full abstract

Cell co-culture plays a key role in inducing the committed differentiation of stem cells in vitro, which mimics the specific tissue microenvironment in vivo by means of co-cultured inducing cells. However, the present cell co-culture systems limit the application of differentiated cells due to the safety and the scale of these systems. This study established a novel microcapsule co-culture system and investigated the probable effect of microencapsulated co-cultured neural cells on neural differentiation of mesenchymal stem cells (MSCs) ex vivo. Mouse bone marrow-derived MSCs were co-cultured with SHSY5Y cells microencapsulated in alginatepolylysine-alginate (APA) microcapsules. The quantitative and qualitative analysis showed that the expression of Nestin (Nes) was significantly increased at both gene and protein levels in the microcapsule co-culture system compared with other systems without cell co-culture, which indicated that more neural progenitors were obtained from this novel microcapsule co-culture system. According to our results and the unique characteristics of microcapsules, it is possible that large-scale cell co-culture system based on the combination of microcapsule and bioreactor technologies will be developed to generate numerous MSCs-derived neural progenitors for clinical applications in the future.

View full abstract

The purposes of this study were to compare cranial base morphology in different types of sagittal malocclusion and to explore regular patterns.
Fifty-six cases of Class I, II and III malocclusion (age: 10-15 years old) with average angle were selected; this comprised 17 cases in the Angle Class I group, 20 cases in the Class II group and 19 cases in the Class III group. The analysis of the cranial base index for the three groups was performed, including one-way analysis of variance for paired comparison.
Significant differences were found among the three groups for posterior cranial base length, which gradually decreased from Class I via Class II to Class III. The gradual decrease of intermediate cranial base angle from Class I to Class III showed statistical differences. Furthermore, there were gradual increases of anterior cranial base angle and BAS-FH angle, which also showed statistical differences. The length of the anterior cranial base(S-N) of Class II decreased, and no significant differences were found between Class I and III malocclusion for the length of SN. No significant differences were found for the cranial base angle, sella angle, cranial base angle, posterior cranial base angle and the length of SO-Ar in different sagittal directions.
The structure of the cranial base in sagittal malocclusion presented some regularities, and it could be considered that the growth of the cranial base was involved in the development of malocclusion. The posterior cranial base and sella had a significant influence on the formation of sagittal malocclusion.

View full abstract

To observe the effect of bone formation with Bio-Oss guided by bioresorbable collagen membrane fixing. Four dogs were used in the study. Three 1cm×1cm areas were formed on bilateral mandibles randomly. The experiment include three groups: group A (Bio-OssR); group B (Bio-OssR + collagen membrane + titanium screws fixing); and group C (Bio-OssR + collagen membrane without fixing). The macroscopic, histological and scanning electron microscope observations were performed at 12 weeks postoperation. The percentage of newly-formed bone area was obtained by computer image analysis (Image-Pro Plus Computer Graphic Analysis System). The three groups all formed new bones. Group B: mature osteocytes and Haversian lamellar could be seen, and plenty of bone trabeculae were arranged in an orderly way. Group A: massive osteoblasts and bone trabeculae formation were found. Group C: there were many osteoblasts and bone lacuna, and osteocytes maturity was higher than that of group A. The average area percentage of new bone in group A was less than in groups B and C, and the average area percentage of new bone in group B was the highest (compared with groups A and C, P<0.05). These data suggest that the bone formation effectiveness of Bio-OssR combined with collagen membrane fixing was better than that of Bio-OssR only and collagen membrane without fixing.

View full abstract

Fetal tissue-derived mesenchymal stem cells (MSCs) may offer greater clinical utility because they possess unique properties over bone marrow (BM) MSCs. Although the continuous passage process can generate numerous MSCs for clinical applications, this process may also have an important effect on the bological characteristics of fetal MSCs. In this study, the proliferation, stemness and cardiac differentiation properties of umbilical cord (UC) Wharton’s Jelly-derived MSCs (WJ MSCs) at different passages (3, 7 and 14) was investigated. It was found that WJ MSC proliferation rate was decreased during the continuous passage process. And the ESC marker gene (Oct3/4, Nanog) expression in WJ MSCs also decreased gradually, while the early mesoderm marker gene (Vimentin) was highest at passage 7. Moreover, the cardiac marker gene (Nkx2.5) expression in differentiated MSCs increased during the continuous passage after cardiac induction. Our results may provide some useful information for stem cell therapy based on WJ MSCs.

View full abstract

Squamous cell carcinoma is a frequently occurring malignant tumor in the human oral cavity. Its treatment usually includes surgical removal of the tissue with pathological changes, as well as radiotherapy and chemotherapy. Surgical removal of the cancerous tissue (combined radical operation) will unavoidably lead to changes in the tissue structure in the local area, and consequently result in changes in the varieties and amounts of the colonized flora. There are currently no reports regarding this possibility. The purpose of this study was to investigate the distribution of bacterial flora in the lesion area of oral squamous cell carcinoma before and after operations. The results obtained from this investigation may be used as a reference point in the treatment of oral squamous carcinoma and the prevention of postoperative infection.The objective of this study was to investigate the distribution of bacterial flora in the lesion area of oral squamous cell carcinoma, before and after operations, and to determine the effects of surgical manipulations on oral bacteria. Forty-two subjects with oral squamous cell carcinoma were selected, each was diagnosed definitively by biopsy and histology, and a combined radical operation was performed. The total number of viable colonies of bacteria as well as the isolation frequency and constituent ratio of each kind of bacteria in the lesion area were measured before and after the operations.In the preoperative lesion of oral squamous cell carcinoma, Streptococci constituted 69.15% of the isolates; Prevotella, 2.47%: Neisseria, 6.70%; Gram-positive anaerobic bacilli, 4.68%; Gram-negative anaerobic bacilli, >4.17%; and other bacteria made up less than 4.07% of the flora. In the postoperative lesion, Streptococci made up 76.99% of the total value; Prevotella, 10.93%; Gram-positive anaerobic bacilli, 6.30%, and other bacteria <3.17% of the total viable counts.

View full abstract

The object of this study was to determine the characteristics of central odontogenic fibroma (COF) in order to help achieve a correct diagnosis. Central odontogenic fibroma, which tends to be epithelium-poor, is an extremely rare type of odontogenic fibroma. The lack of data concerning COF, due to its low incidence, can make this entity difficult to diagnose. We herein report an epithelium-poor type of COF of the mandible, which we examined immunohistologically. We also provide a review of the previous English literature to expand the knowledge about this disease. Positive reactions for vimentin and negative reactions for desmin and α-smooth muscle actin (α-SMA) in COFs were common findings in the previous reports. We also noted similar immunohistological findings. Our data (vimentin positive, α-SMA and desmin negative) should contribute to correctly diagnosing epithelium-poor type COF.

View full abstract

Primary malignant melanoma (MM) in otorhinolaryngology is a rare disease that has a poor prognosis. There has been a significant increase in the incidence of MM in the nasal cavity in recent years. We performed surgery on four Turkish patients for intranasal MM during a 6-month period, and the cases were reviewed retrospectively. One patient underwent open surgery, and the other three underwent endoscopic resection. All four patients had microscopically negative surgical margins. One patient received treatment with radiotherapy during the postoperative period. A negative surgical margin and removal of mucosal melanocyt areas are important criteria for surgical success and a better prognosis.

View full abstract