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Background Numerous studies have demonstrated that the increasingly diverse US population benefits from access to diverse healthcare providers from similarly diverse backgrounds. Physician assistant (PA) education programs have striven to increase the diversity of the profession, which is predominantly non-Hispanic white, by focusing on admitting historically underrepresented students. However, strategies such as holistic admissions are predicated on the existence of diverse applicant pools. While studies have examined correlates of matriculation into a medical education program, this study looks earlier in the pipeline and investigates whether applicant – not matriculant – pool diversity varies among PA programs with different characteristics. Methods Data were drawn from the 2017-2018 Central Application Service for PAs admissions cycle. Applications to programs with pre-professional tracks and applicants missing race/ethnicity data were excluded, resulting in data from 26,600 individuals who applied to 189 PA programs. We summarized the racial and ethnic diversity of each program’s applicant pools using: (1)the proportion of underrepresented minority (URM) students, (2)the proportion of students with backgrounds underrepresented in medicine (URiM), and (3)Simpson’s diversity index of a 7-category race/ethnicity combination. We used multiple regressions to model each diversity metric as a function of program characteristics including class size, accreditation status, type of institution, and other important features. Results Regardless of the diversity metric examined, we found that applicant diversity was higher among provisionally accredited programs and those receiving more applications. We also identified trends suggesting that programs in more metropolitan areas were able to attract more diverse applicants. Programs that did not require the GRE were also able to attract more diverse applicants when considering the URM and SDI metrics, though results for URiM were not statistically significant. Conclusions Our findings provide insights into modifiable (e.g., GRE requirement) and non-modifiable (e.g., provisionally accredited) program characteristics that are associated with a diverse applicant pool.

Introduction This study aimed to examine the bone-forming ability of medium-cross-linked recombinant collagen peptide (mRCP) particles developedbased on human collagen type I, contains an arginyl-glycyl-aspartic acid-rich motif, fabricated as bone filling material, compared to that of the autologous bone graft. Methods Calvarial bone defects were created in immunodeficient rats though a surgical procedure. The rats were divided into 2 groups: mRCP graft and tibia bone graft (bone graft). The bone formation potential of mRCP was evaluated by micro-computed tomography and hematoxylin-eosin staining at 1, 2, 3, and 4 weeks after surgery, and the data were analyzed and compared to those of the bone graft. Results The axial volume-rendered images demonstrated considerable bony bridging with the mRCP graft, but there was no significant difference in the bone volume and bone mineral density between the mRCP graft and bone graft at 4 weeks. The peripheral new bone density was significantly higher than the central new bone density and the bottom side score was significantly higher than the top side score at early stage in the regenerated bone within the bone defects. Conclusion These results indicate that mRCP has a high potential of recruiting osteogenic cells, comparable to that of autologous bone chips., Highlights • Bone formation potential of mRCP were comparable to that of autogenous bone. • mRCP particles exhibit high new bone formation potential in the calvaria defect. • Bone bridging was observed over the entire defect in mRCP graft at 4 weeks. • mRCP has a high potential of recruiting osteogenic cells comparable to bone graft.

Purpose The aim of this study was to assess the response of dental pulp associated with donor or host cells in the pulp chamber and root canal after extra-oral transplantation. Methods Wild type or green fluorescent protein (GFP) transgenic first molars from 3-week, 6-week, and 12-week mice were transplanted into the subcutaneous layer of GFP mice or wild type mice. The teeth were histologically and immunohistochemically examined at 5 weeks after transplantation. Results Blood vessels present in the original coronal pulp had anastomosed with those from the recipient tissue that had invaded the root canal. Two distinct eosin-stained extracellular matrices were observed in the pulp chamber and root canal. Acellular matrix composed of nestin-positive, odontoblast-like cells invaded from the outside and was seen in the root canal of 3-week teeth. Cellular matrix comprising alkaline phosphatase (ALP)-positive fibroblast-like cells appeared in the original coronal pulp. In the root canal of the 6-week and 12-week teeth, cellular extracellular matrix consisting of ALP-positive fibroblast-like cells had invaded the recipient tissue. Conclusion Dental pulp from immature teeth might be able to regenerate dentin-like tissue. This model could be useful in the development of an optimized vitalization treatment.

Introduction In the present study, we examined the effect of oriented collagen tube (OCT) implantation on the recovery of sensory function of the resected rat sciatic nerve. Materials and methods After a 10-mm long portion of the sciatic nerve of a rat was resected, an OCT was placed in the site of nerve defect. Recovery of the sensory function was evaluated using Von Frey test every 3 days after surgery. The regenerated tissue were histologically and ultrastructurally analyzed 2 and 4 weeks after the surgery. Results The sensory reflexes of the OCT group were restored to the level of that of the intact group after 15 days. Hematoxylin and eosin staining revealed the cross-linking between the proximal and distal stumps after 2 weeks. After 4 weeks, Luxol Fast Blue and immunohistochemical staining revealed the presence of myelin sheath from the proximal to distal region of the regenerated tissue and S100B staining confirmed the presence of Schwann cells. Interestingly, no myelin sheath was ultrastructurally observed around the regenerated axons at the central region after 2 weeks. Conclusions These results suggest that OCTs facilitate the recovery of sensory function. Additionally, the non-myelinated axons contributed to the recovery of the sensory function., Highlights • Von Frey test results in the OCT group on POD 15 were comparable at the sham group. • OCT group showed regeneration of unmyelinated axons in 2 weeks. • Myelination was observed from proximal to distal after 4 weeks OCT implantation. • In the OCT group, a large number of blood vessels were observed in nerve in 2 weeks.

Aims/Introduction The association between diabetes and periodontal disease is considered to be bidirectional. However, there is still controversy surrounding the relationship between periodontal disease and type 1 diabetes. We investigated whether insulin improves periodontitis without any local treatments for periodontitis under type 1 diabetes conditions using the ligature‐induced experimental periodontitis model. Materials and Methods Type 1 diabetic rats were induced by streptozotocin injection. Experimental periodontitis was induced by ligature in normal and diabetic rats. Half of the diabetic rats were treated with insulin. Two weeks after the ligature, periodontitis was evaluated. Results Insulin treatment significantly improved inflammatory cell infiltration and inflammatory cytokine gene expression, leading to suppression of alveolar bone loss, in the periodontitis of diabetic rats. Insulin also suppressed the periodontitis‐increased nitric oxide synthase‐positive cells in periodontal tissue of the diabetic rats. Even without induction of periodontitis, diabetic rats showed decreased gingival blood flow and an increased number of nitric oxide synthase‐positive cells in the gingiva and alveolar bone loss compared with normal rats, all of which were ameliorated by insulin treatment. We further confirmed that insulin directly suppressed lipopolysaccharide‐induced inflammatory cytokine expressions in THP‐1 cells. Conclusions There were abnormalities of periodontal tissue even without the induction of periodontitis in streptozotocin‐induced diabetic rats. Insulin treatment significantly ameliorated periodontitis without local periodontitis treatment in diabetic rats. These data suggest the therapeutic impacts of insulin on periodontitis in type 1 diabetes., There was a slight increase in the numbers of inflammatory cells in the gingiva on the periodontitis side of normal rats and on the control side of diabetic rats. The inflammatory cells were markedly increased on the periodontitis side of diabetic rats. Insulin treatment decreased the inflammatory cells in the periodontitis gingiva of diabetic rats.

Risk factors contributing to sepsis-related mortality include clinical conditions such as cardiovascular disease, chronic lung disease, and diabetes, all of which have also been shown to be associated with air pollution exposure. However, the impact of chronic exposure to air pollution on sepsis-related mortality has been little studied. METHODS: In a cohort of 53 million Medicare beneficiaries (228,439 sepsis-related deaths) living across the conterminous United States between 2000 and 2008, we examined the association of long-term PMA 10 μg/mLong-term PM

Tissue engineering is a promising approach to supplement existing treatment strategies for craniofacial bone regeneration. In this study, a type I collagen scaffold made from a recombinant peptide (RCP) with an Arg-Gly-Asp motif was developed, and its effect on regeneration in critical-size mandibular bone defects was evaluated. Additionally, the combined effect of the scaffold and lipid-free dedifferentiated fat (DFAT) cells was assessed. Briefly, DFAT cells were separated from mature adipocytes by using a ceiling culture technique based on buoyancy. A 3 cm × 4 cm critical-size bone defect was created in the rat mandible, and regeneration was evaluated by using RCP with DFAT cells. Then, cultured DFAT cells and adipose-derived stem cells (ASCs) were seeded onto RCP scaffolds (DFAT/RCP and ASC/RCP) and implanted into the bone defects. Micro-computed tomography imaging at 8 weeks after implantation showed significantly greater bone regeneration in the DFAT/RCP group than in the ASC/RCP and RCP-alone groups. Similarly, histological analysis showed significantly greater bone width in the DFAT/RCP group than in the ASC/RCP and RCP-alone groups. These findings suggest that DFAT/RCP is effective for bone formation in critical-size bone defects and that DFAT cells are a promising source for bone regeneration.

This study aimed to examine the optimal cross-link density of recombinant peptide (RCP) particles, based on human collagen type I, for bone reconstruction in human alveolar cleft. Low- (group 1), medium- (group 2), and high- (group 3) cross-linked RCP particles were prepared by altering the duration of the heat-dependent dehydration reaction. Rat palatine fissures (n = 45), analogous to human congenital bone defects, were examined to evaluate the potential of bone formation by the three different RCP particles. Microcomputed tomography images were obtained to measure bone volume and bone mineral density at 4, 8, 12, and 16 weeks post grafting. Specimens were obtained for histological analysis at 16 weeks after grafting. Additionally, alkaline phosphatase and tartrate acid phosphatase staining were performed to visualize the presence of osteoblasts and osteoclasts. At 16 weeks, bone volume, bone mineral density, and new bone area measurements in group 2 were significantly higher than in any other group. In addition, the number of osteoblasts and osteoclasts on the new bone surface in group 2 was significantly higher than in any other group. Our results demonstrated that medium cross-linking was more suitable for bone formation—and could be useful in human alveolar cleft repairs as well.

Background Extracellular vesicles (EVs) are known to be secreted by various cells. In particular, mesenchymal stem cell (MSC)-derived EVs (MSC-EVs) have tissue repair capacity and anti-inflammatory properties. Dental pulp stem cells (DPSCs), which are MSCs isolated from pulp tissue, are less invasive to the body than other MSCs and can be collected from young individuals. In this study, we investigated the efficacy of EVs secreted by DPSCs (DPSC-EVs) for bone formation. Methods DPSC-EVs were isolated from the cell culture medium of DPSCs. DPSC-EVs were unilaterally injected along with collagen (COL), beta-tricalcium phosphate (β-TCP) or hydroxyapatite (HA) into rat calvarial bone defects. The effects of DPSC-EVs were analyzed by micro-computed tomography (micro-CT) and histological observation. Results Micro-CT showed that administration of DPSC-EVs with the abovementioned scaffolds resulted in bone formation in the periphery of the defects. DPSC-EVs/COL specifically resulted in bone formation in the center of the defects. Histological observation revealed that DPSC-EVs/COL promoted new bone formation. Administration of DPSC-EVs/COL had almost the same effect on the bone defect site as transplantation of DPSCs/COL. Conclusions These results suggest that DPSC-EVs may be effective tools for bone tissue regeneration.

Regular flight inspection of navigation systems, such as instrument landing system (ILS) and the VHF omnidirectional radio range (VOR), is an important part of maintenance to ensure safe flight operations. Usually, this is done with aircraft flying and measuring at trajectories according to international recommendations from the ICAO. With the arising technology of unmanned aerial vehicles (UAVs), such flight inspections could be performed in a much more economic and efficient manner, in particular, if combined with nearfield measurement technology, allowing farfield predictions anywhere in space without limitations to particular flight trajectories. This contribution discusses an innovative approach for such nearfield inspections with UAV as research focus of the navigation aid antenna characterization—next generation (NAVANT-NG) project with corresponding requirements and first measurement results. In this contribution, both the dynamic range and the accuracy of phase measurements and stability are investigated. In particular, the accuracy and stability of phase measurements are a crucial part in such nearfield measurements. First measurement results with a test antenna and a UAV demonstrate the feasibility of proposed nearfield measurements.

Background: The US population is maturing. As of 2020, over 52 million (16%) people are age 65 or older. With a citizenry that is increasingly "gray," the nation is short of medical providers who specialize in geriatric medical care. For example, the number of geriatrician physicians per 10,000 adults 65 years and older has decreased since 2000, with approximately 5,300 in 2018. Nurse practitioners in geriatric medical care numbered 598 in 2018. Considering that the projected needs by 2030 will be over 30,000, the trajectory of geriatricians is becoming increasingly inadequate for the aging population. Physician assistants (PA) are another class of providers that are filling this geriatric medical care role, although little has been published. To address this role of PAs a study was undertaken. Methods: The National Commission on Certification of Physician Assistants databank provided the number and characteristics of PAs in geriatric medicine and compared them to all other certified PAs. Analyses included descriptive statistics, Chi-Square, and Wilcoxon Rank Sum tests for comparisons between PAs practicing in geriatric medical care vs. all other specialties. Where a comparison between PAs in geriatrics and other specialties was made, a P value of .05 or less was considered statistically significant. Results: As of 2018, there were 794 certified PAs, or 0.8% of the certified PA workforce, in geriatric medical care. This cadre has grown significantly since 2013, both in total number (increasing over 373%) and as a percentage of the PA workforce. The median age of certified PAs in geriatrics is 45 years, and 79% are female. Almost half (46%) of PAs in geriatric medicine work in extended care facilities or nursing homes, which differs from PAs in non-geriatrics care. Another 8% work in government facilities and 8% in rehabilitation facilities. In 2018, the mean annual income for this PA group was $106,680. Conclusions: As the American population continues to age, the relative growth of PAs in geriatric medicine makes them a natural part of the solution to the projected physician geriatrician deficit. The role of PAs in geriatric medical care remains to be explored.

An inferior alveolar nerve (IAN) injury is a common clinical problem that can affect a patients' quality of life. Cellular therapy has been proposed as a promising treatment for this injury. However, the current experimental models for IAN injury require surgery to create bone windows that expose the nerve, and these models do not accurately mimic human IAN injuries. Therefore, in this study, a novel experimental model for IAN injury has been established in rats. Using this model, the effects of Schwann cells and their role in the recovery from IAN injuries were investigated. Schwann cells were isolated from rat sciatic nerves and cultured. The first molar in the mandible was extracted and the IAN was immediately injured for 30 min by inserting an insect pin. Then, the Schwann cells or culture medium were transplanted into the extracted sockets of the cell and injury groups, respectively. After the surgery, the cell group displayed significantly increased sensory reflexes in response to mechanical stimulation, regenerated IAN width, and myelin basic protein-positive myelin sheaths when compared with the injury group. In conclusion, a novel animal experimental model for IAN injury has been developed that does not require the creation of a bone window to evaluate the impacts of cell transplantation and demonstrates that Schwann cell transplantation facilitates the regeneration of injured IANs.

Background: The US population is maturing. As of 2020, over 16% (52 million people) are age 65 or older. With a citizenry that is increasingly "gray," the nation is short of medical providers who specialize in geriatric medical care. For example, the number of geriatrician physicians per 10,000 adults 65 years and older has decreased since 2000, with approximately 5,300 in 2018. Nurse practitioners in geriatric medical care numbered 598 in 2018. Considering that the projected needs by 2030 will be over 30,000, the trajectory of geriatricians is becoming increasingly inadequate for the aging population. Physician assistants (PA) are another class of providers that are filling this geriatric medical care role, although little has been published. To address this role of PAs a study was undertaken. Methods: The National Commission on Certification of Physician Assistants databank provided the number and characteristics of PAs in geriatric medicine and compared them to all other certified PAs. Analyses included descriptive statistics, Chi-Square, and Wilcoxon Rank Sum tests for comparisons between PAs practicing in geriatric medical care vs. all other specialties. Where a comparison between PAs in geriatrics and other specialties was made, a P value of .05 or less was considered statistically significant. Results: As of 2018, there were 794 certified PAs, or 0.8% of the certified PA workforce, in geriatric medical care. This cadre has grown significantly since 2013, both in total number (increasing over 373%) and as a percentage of the PA workforce. The median age of certified PAs in geriatrics is 45 years, and 79% are female. Almost half (46%) of PAs in geriatric medicine work in extended care facilities or nursing homes, which differs from PAs in non-geriatrics care. Another 8% work in government facilities and 8% in rehabilitation facilities. In 2018, the mean annual income for this PA group was $106,680. Conclusions: As the American population continues to age, the relative growth of PAs in geriatric medicine makes them a natural part of the solution to the projected physician geriatrician deficit. The role of PAs in geriatric medical care remains to be explored.

The aim of this study was to investigate root canal configurations in maxillary first and second molars from a Japanese population, as well as the relationship between the root canal number and root concavity depth, using micro-computed tomography. Maxillary first (N = 74) and second (N = 70) molars from a Japanese population were used. Virtual horizontal sections were created, and the number of root canals and the degree of root concavity were measured. Mesiobuccal (MB) roots were categorized into Group 1 (with a single root canal) or Group 2 (with two or more root canals). The relationship between the root canal number and root concavity depth was evaluated using the Mann–Whitney U test. Approximately 51% and 35% of the MB roots in the three-rooted maxillary first and second molars, respectively, had two or more root canals. The depths of the root concavities in maxillary first molars differed significantly between Groups 1 and 2 at the mesial and distal sides of the MB root, in the section 2 mm apical to the furcation area (p

Background and objective Little is known about the anatomical characteristics of root morphology in molars lost due to periodontal reason. The aim of this study was to study root morphology in maxillary and mandibular molars lost due to periodontitis by investigating the frequency of root fusion, classifying fusion types, and measuring radicular groove depth by micro-computed tomography. Material and methods Ninety-eight posterior teeth were collected from 87 Japanese patients during the study period. Of these, maxillary (N = 36) and mandibular (N = 22) second molars lost most frequently were assessed for root fusion and morphology. Results The 36 maxillary second molars included nine (25%) teeth with a single root, 14 (39%) with two roots, and 13 (36%) with three roots. Of the 23 maxillary second molars with fused (1 and 2) roots, there were 11 (48%), 2 (9%), 1 (4%), 1 (4%), 3 (13%), and 5 (22%) teeth with root types 1-6, respectively. The 22 mandibular second molars comprised 14 (64%) teeth with a single root, 7 (32%) with two roots, and one (4%) with three roots. Of the 14 mandibular second molars with a fused (1) root, 12 (86%) had a C-shaped root and two (14%) had a non-C-shaped root. Conclusion We observed a higher frequency of root fusion in the present study compared with that reported by previous studies using randomly selected second molars.

Periodontitis is one of the diabetic complications due to its high morbidity and severity in patients with diabetes. The prevention of periodontitis is especially important in diabetic patients because the relationship between diabetes and periodontitis is bidirectional. Here, we evaluated the impacts of glucagon-like peptide-1 (GLP-1) receptor agonist liraglutide on the amelioration of periodontitis. Five-wk-old Male Sprague–Dawley (SD) rats ( n = 30 ) were divided into 3 groups: normal, periodontitis, and periodontitis with liraglutide treatment groups. Periodontitis was induced by ligature around the maxillary second molar in SD rats. Half of the rats were administered liraglutide for 2 weeks. Periodontitis was evaluated by histological staining, gene expressions of inflammatory cytokines in gingiva, and microcomputed tomography. Periodontitis increased inflammatory cell infiltration, macrophage accumulation, and gene expressions of tumor necrosis factor-α and inducible nitric oxide synthase in the gingiva, all of which were ameliorated by liraglutide. Liraglutide decreased M1 macrophages but did not affect M2 macrophages in periodontitis. Moreover, ligature-induced alveolar bone resorption was ameliorated by liraglutide. Liraglutide treatment also reduced osteoclasts on the alveolar bone surface. These results highlight the beyond glucose-lowering effects of liraglutide on the treatment of periodontitis.

A 3, 3'-diaminobenzidine (DAB)-based method was used to detect the localization of endogenous peroxidase activity in Indian rhinoceros (Rhinoceros unicornis) parotid gland acinar cells. The tissue had previously been resin-embedded in gelatin capsules for routine electron microscopic observations and thus pre-incubation for endogenous peroxidase analysis was not possible. We attempted to demonstrate the relationship between secretory granules (SGs) in resin ultrathin sections of Indian rhinoceros parotid gland acinar cells and endogenous peroxidase activity. A JEM 1400 Plus scanning transmission electron microscope (STEM) was used to conduct energy dispersive X-ray spectroscopy (EDS) analysis of the presence of nitrogen generated by the DAB reaction in bipartite structural SG consisting of a dense body (or core). The mapping patterns of nitrogen were restricted to the dense body. We observed nitrogen localized in the rough endoplasmic reticulum (ER), nuclear envelope (NE) and several components of the Golgi apparatus (G) of rhinoceros parotid gland acinar cells participating in the synthetic pathway of secretory proteins. Moreover, we established a nitrogen-detection method by EDS analysis of rhinoceros parotid gland. The reliability of the method was validated by comparison of the test group (peroxidase detection in ultrathin resin sections) and the control group (ordinary peroxidase detection in semi-thin sections following glutaraldehyde pre-fixation) of rat submandibular gland. The same mapping patterns of nitrogen were detected by DAB reaction in the SG, ER, NE and G in these two groups. Hence, EDS-STEM approaches for endogenous peroxidase post-incubation analysis will prove useful for advanced cytochemical analysis for the identification of any other resin sections.

Fe50Pt50 thick-films were electroplated on a Ta substrate using a direct current, and we evaluated the effect of Na ion concentration in plating baths on the magnetic properties of the annealed films. With increasing NaCl content from 2 to 30 g/L, the coercivity of the annealed Fe50Pt50 films increased from 700 kA/m to approximately 900 kA/m. For obtaining further experimental evidence for the increase in the coercivity, we employed trisodium citrate instead of NaCl as an additive in the plating bath. Consequently, as the addition of the trisodium citrate as well as NaCl increased the coercivity, we concluded that a plating bath with high Na ion concentration is effective to obtain the Fe-Pt thick-films with high coercivity., Journal of Alloys and Compounds, 752, pp.133-136; 2018

Dental pulp is known to play crucial roles in homeostasis of teeth and periodontal tissue. Although resorption of bone around the roots of nonvital teeth is occasionally observed in clinical practice, little is known about the role of dental pulp in osteoclastogenesis. Here we evaluated the effects of conditioned medium (CM) from rat dental pulp on osteoclastogenesis. It was found that the CM reduced the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclasts, but did not alter the mRNA levels of nuclear factor of activated T-cells, cytoplasmic 1 and TRAP. To further understand the mechanism behind these results, we evaluated the effects of CM on osteoclast precursors and found that the CM removed cell processes, resulting in a significant reduction in the number of attached cells and an increase in the number of freely floating cells. Furthermore, the CM suppressed the mRNA levels of focal adhesion kinase and paxillin, which are involved in cell adhesiveness and spreading. Collectively, the present results show that CM from dental pulp serves as an inhibitor of osteoclastogenesis by reducing the number and adhesiveness of osteoclast precursors, suggesting novel therapeutic applicability for osteoporosis.

Background: Although bone tissue engineering for dentistry has been studied for many years, the clinical outcome for severe cases has not been established. Furthermore, there are limited numbers of studies that include long-term follow-up. In this study, the safety and efficacy of bone tissue engineering for patients with a severely atrophic alveolar bone were examined using autogenous bone marrow stromal cells (BMSCs), and the long-term stability was also evaluated. Methods: BMSCs from iliac bone marrow aspirate were cultured and expanded. Then, induced osteogenic cells were transplanted with autogenous platelet-rich plasma (PRP) and β-tricalcium phosphate granules (β-TCP) for maxillary sinus floor and alveolar ridge augmentation. Eight patients (two males and six females) with an average age of 54.2 years underwent cell transplantation. Safety was assessed by monitoring adverse events. Radiographic evaluation and bone biopsies were performed to evaluate the regenerated bone. Results: The major population of transplanted BMSCs belonged to the fraction of CD34−, CD45dim, and CD73+ cells, which was only 0.065% of the total bone marrow cells. Significant deviations were observed in cell growth and alkaline phosphatase activities among individuals. However, bone regeneration was observed in all patients and the average bone area in the biopsy samples was 41.9% 6 months following transplantation, although there were also significant deviations among each case. No adverse events related to the transplants were observed. In the regenerated bone, 27 out of 29 dental implants were integrated. Dental implants and regenerated bone were stable for an average follow-up period of 7 years and 10 months. Conclusions: Although individual variations were observed, the results showed that bone tissue engineering using BMSCs with PRP and β-TCP was feasible for patients with severe atrophic maxilla throughout a long-term follow-up period and was considered safe. However, further studies with a larger number of cases and controls to confirm the efficacy of BMSCs and the development of a protocol to establish a reproducible quality of stem cell-based graft material will be required.

Background 3,3'-diaminobenzidine tetrazolium (DAB)-based methods have been developed to detect the localization of peroxidase (PO) activity. Histochemically, endogenous PO activity has been localized to acini of human and rodent salivary glands. This suggests that the enzyme may be used as a convenient marker of differentiated acinar cells to study factors that influence the development of the rat submandibular gland. We also investigated endogenous PO localization differences between rodent and insectivora ( Suncus murinus) major salivary glands by light and electron microscopy. Moreover, ectopic sublingual gland-like tissue was found in the resin-embedded semi-thin sections of DAB-reacted hamster submandibular gland by confocal laser scanning microscopy. Highlight Reflectance-mode confocal laser scanning microscopy was employed to visualize sites of PO activity in ectopic sublingual gland-like tissue of the hamster submandibular gland. Conclusion The technique proposed here may result in novel applications for DAB-based histochemistry.

Dental pulp has garnered much attention as an easily accessible postnatal tissue source of high-quality mesenchymal stem cells (MSCs). Since the discovery of dental pulp stem cells (DPSCs) in permanent third molars, stem cells from human exfoliated deciduous teeth and from supernumerary teeth (mesiodentes) have been identified as a population distinct from DPSCs. Dental pulp is divided into 2 parts based on the developing stage: the coronal pulp and the radicular pulp. Root formation begins after the crown part is completed. We performed a sequential study to examine the differences between the characteristics of coronal pulp cells (CPCs) and radicular pulp cells (RPCs) from permanent teeth, mesiodentes, and deciduous teeth. Interestingly, although we have not obtained any data on the difference between CPCs and RPCs in permanent teeth, there are some differences between the characteristics of CPCs and RPCs from mesiodentes and deciduous teeth. The MSC characteristics differed between the RPCs and CPCs, and the reprogramming efficiency for the generation of induced pluripotent stem cells was greater in RPCs than in CPCs from deciduous teeth. The proportion of CD105+ cells in CPCs versus that in RPCs varied in mesiodentes but not in permanent teeth. The results indicate that the proportion of CD105+ cells is an effective means of characterizing dental pulp cells in mesiodentes. Taken together, the stem cells in deciduous and supernumerary teeth share many characteristics, such as a high proliferation rate and an immunophenotype similar to that of DPSCs. Thus, mesiodentes accidentally encountered on radiographs by the general dental practitioner might be useful for stem cell therapy.

We investigated the association between human polymorphonuclear leukocytes (PMNs) and non-opsonized Tannerella forsythia ATCC 43037 displaying a serum-resistant surface layer (S-layer). When PMNs were mixed with T. forsythia in suspension, the cells phagocytosed T. forsythia cells. Nitro blue tetrazolium (NBT) reduction, indicative of O2- production, was observed by light microscopy; cerium (Ce) perhydroxide deposition, indicative of H2 O2 production, was observed by electron microscopy. We examined the relationship between high-molecular-weight proteins of the S-layer and Ce reaction (for T. forsythia phagocytosis) using electron microscopic immunolabeling. Immunogold particles were localized within the PMNs and on cell surfaces, labelling at the same Ce-reacted sites where the S-layer was present. We then used energy dispersive spectroscopy (EDS)-scanning transmission electron microscope (STEM) to perform Ce and nitrogen (N) (for S-layer immunocytochemistry) elemental analysis on the phagocytosed cells. That is, the elemental mapping and analysis of N by EDS appeared to reflect the presence of the same moieties detected by the 3,3'-diaminobenzidine-tetrahydrochloride (DAB) reaction with horseradish peroxidase (HRP)-conjugated secondary antibodies, instead of immunogold labeling. We focused on the use of EDS-STEM to visualize the presence of N resulting from the DAB reaction. In a parallel set of experiments, we used EDS-STEM to perform Ce and gold (Au; from immunogold labeling of the S-layer) elemental analysis on the same phagocytosing cells.

We previously generated induced pluripotent stem (iPS) cells from human dental pulp cells of deciduous teeth. Neural crest cells (NCCs) play a vital role in the development of the oral and maxillofacial region. Therefore, NCCs represent a cell source for bone, cartilage, and tooth-related tissue engineering. In this study, we examined whether iPS cells are capable of differentiating into NCCs through modification of the human embryonic stem cell protocol. First, iPS cells were dissociated into single cells and then reaggregated in low-cell-adhesion plates with neural induction medium for 8 days in suspension culture to form neurospheres. The neurospheres were transferred to fibronectin-coated dishes and formed rosette structures. The migrated cells from the rosettes abundantly expressed NCC markers, as evidenced by real-time polymerase chain reaction, immunofluorescence, and flow cytometric analysis. Furthermore, the migrated cells exhibited the ability to differentiate into neural crest lineage cells in vitro. They also exhibited tissue-forming potential in vivo, differentiating into bone and cartilage. Collectively, the migrated cells had similar characteristics to those of NCCs. These results suggest that human dental pulp cell-derived iPS cells are capable of differentiating into NCCs. Therefore, iPS cell-derived NCCs represent cell sources for bone and cartilage tissue engineering.

Bone marrow-derived multipotent stromal cells (BMSCs) have potent antiinflammatory effects. This study aimed to investigate the antiinflammatory potential of BMSCs using a mouse model of ligature-induced periodontitis. BMSCs were isolated from the femurs and tibiae of mice. Periodontitis was induced by placing a ligature around the right maxillary second molar. After 3 days, the mice were administered BMSC in the gingiva of the mesial interdental papilla around the ligatured molar. The ligatured and non-ligatured mice that were not administered BMSC served as controls. Differences in inflammatory infiltration and bone resorption around the roots of the second molar were assessed and were subsequently quantified using microcomputed tomography (micro-CT), histological analysis, and tartrate-resistant acid phosphatase (TRAP) staining. Micro-CT revealed that alveolar bone loss around the ligatured molars increased in a time-dependent manner; however, the effect was significantly less in BMSC-treated mice compared with ligatured control mice. Tissue histopathology revealed that BMSC administration mitigated inflammatory infiltration in ligatured BMSC mice. In addition, the number of TRAP-positive osteoclasts was markedly elevated in ligatured control mice compared with those in BMSC-treated mice. These findings indicate that local BMSC administration can mitigate inflammation and alveolar bone resorption, suggesting that administering BMSC leads to new therapeutics for periodontitis.

The rat palatine fissure is anatomically similar to human alveolar cleft. In this study, we examined potential bone repair by an autologous bone implant and beta-tricalcium phosphate (β-TCP) using rat palatine fissure as a model. Autologous bone chips or β-TCP granules were implanted into the rat palatine fissure. Our model demonstrated that higher bone volume and bone mineral density were achieved with autologous bone graft than with β-TCP. We have provided the first demonstration of the suitability of the rat palatine fissure as the implant site to simulate the transplantation of bone graft materials into human alveolar cleft.

Bone marrow-derived mesenchymal stem cells (BMMSCs) remain the most widely used source of osteogenic cells in bone tissue engineering research. A cell-based treatment for alveolar ridge augmentation has received attention as an alternative to bone grafting. In the present study, BMMSC transplantation into tooth extraction sockets of C57BL/6J mice was evaluated for alveolar ridge regeneration. The first right maxillary molars were extracted, and then BMMSCs (PDGFRα+ Sca-1+ CD45- TER119- cells) isolated from femoral and tibial bone marrow were immediately transplanted into the extraction sockets. A control group underwent the same procedure except for BMMSC transplantation. Bone formation in the sockets was evaluated using micro-computed tomography and histological and immunohistochemical analyses. At 3 weeks, bone formation in the sockets was more advanced in the experimental group than in the control group. Histological analysis at 6 weeks after transplantation showed that the sockets in the experimental group also contained a greater quantity of bone marrow. Interestingly, socket bone mineral density was lower in the experimental group than in the control group at 6 weeks. These findings suggest that BMMSC transplantation accelerates bone healing and augments bone marrow formation in tooth extraction sockets.

Periodontal disease which consists of gingivitis and periodontitis is one of the diabetic complications due to the high prevalence and the severity. Periodontitis is a chronic inflammation by the infection of Gram-negative bacteria in the periodontal pocket, following the destruction of periodontal tissue. On the other hand, many researches have shown extrapancreatic functions of glucagon-like peptide-1 (GLP-1), including the anti-inflammatory action and the suppression of indirectly bone resorption. In this study, we focused on the therapeutic effects of GLP-1 on periodontitis. Experimental periodontitis was induced by placing a nylon thread ligatureat the cervical portion of the maxillary second molar in Sprague-Dawley rats. Half of the rats were administered GLP-1 receptor agonist, Liraglutide (0.4mg/kg/day). Two weeks after the ligation, periodontitis was evaluated by histological examinations (H-E staining and the immunostaining) and mRNA expressions of inflammatory cytokines. Alveolar bone loss was evaluated by the distance at maximal bone resorption site from cement-enamel junction (CEJ) to the alveolar bone crest, and the bone micro-architecture parameters, using micro-CT and analytical software. We also investigated the anti-inflammatory effects of GLP-1 on monocytes using THP-1 cells. The mRNA expressions of TNF-α, iNOS and Mac1 in gingiva and alveolar bone resorption were significantly increased in the periodontitis rats. Liraglutide significantly suppressed the periodontitis-related inflammatory cytokine expressions and alveolar bone resorption. The part of the bone micro-architecture parameters in periodontitis rats deteriorate, which was not affected by Liraglutide. In vitro study revealed that GLP-1 significantly inhibited lipopolysaccharide-induced TNF-α mRNA expression in THP-1 cells in a dose-dependent manner. In conclusion, GLP-1 may be effective in the treatment of periodontal disease mainly through the suppression of gingival inflammation. Disclosure N. Sawada: None. K. Naruse: None. T. Matsubara: None. N. Nakamura: None. M. Miyabe: None. M. Ito: None. Y. Suzuki: None. K. Adachi: None. S. Kobayashi: None. T. Kikuchi: None. A. Mitani: None. T. Toriumi: None. M. Mizutani: None. M. Honda: None.