Fine-tuned local coordination environment of Pt single atoms on ceria controls catalytic reactivity.

Constructing single atom catalysts with fine-tuned coordination environments can be a promising strategy to achieve satisfactory catalytic performance. Herein, via a simple calcination temperature-control strategy, CeO2 supported Pt single atom catalysts with precisely controlled coordination environments are successfully fabricated. The joint experimental and theoretical analysis reveals that the Pt single atoms on Pt1/CeO2 prepared at 550 °C (Pt/CeO2-550) are mainly located at the edge sites of CeO2 with a Pt-O coordination number of ca. 5, while those prepared at 800 °C (Pt/CeO2-800) are predominantly located at distorted Ce substitution sites on CeO2 terrace with a Pt-O coordination number of ca. 4. Pt/CeO2-550 and Pt/CeO2-800 with different Pt1-CeO2 coordination environments exhibit a reversal of activity trend in CO oxidation and NH3 oxidation due to their different privileges in reactants activation and H2O desorption, suggesting that the catalytic performance of Pt single atom catalysts in different target reactions can be maximized by optimizing their local coordination structures.

Atomic-Scale Structure and Catalysis on Positively Charged Bimetallic Sites for Generation of H2.

Here, we report that a cationic bimetallic site consisting of one Pd and three Zn atoms (Pd1Zn3) supported on ZnO (Pd1Zn3/ZnO) exhibits an extraordinarily high catalytic activity for the generation of H2 through methanol partial oxidation (MPO) that is 2-3 orders of magnitude higher than that of a metallic Pd-Zn site on Pd-Zn nanoalloy (Pd-Zn/ZnO). Computational studies uncovered that the positively charged Pd atom of the subnanometer Pd1Zn3 bimetallic site largely decreases the activation barrier for dehydrogenation of methanol as compared to a metallic Pd atom of Pd-Zn alloy, thus switching the rate-determining step of MPO from methanol dehydrogenation over a Pd-Zn alloy with high barrier to the O2 dissociation step on a cationic Pd1Zn3 site with a low barrier, which is supported by our kinetics studies. The significantly higher catalytic activity and selectivity for H2 production over a cationic bimetallic site suggest a new approach to design bimetallic catalysts.

Adatom Extraction from Pristine Metal Terraces by Dissociative Oxygen Adsorption: Combined STM and Density Functional Theory Investigation of O/Ag(110).

The reconstruction and modification of metal surfaces upon O_{2} adsorption plays an important role in oxidation processes and in gauging their catalytic activity. Here, we show by employing scanning tunneling microscopy and the ab initio density functional theory that Ag atoms are extracted from pristine (110) terraces upon O_{2} dissociation, resulting in vacancies and in Ag-O complexes. The substrate roughening generates undercoordinated atoms and opens pathways to the Ag subsurface layer. With increasing O coverage, multiple vacancies give rise to remarkable structures. The mechanism is expected to be very general depending on the delicate interplay of energy and entropy, so that it may be active for other materials at different temperatures.

Accelerated biodegradation of silk sutures through matrix metalloproteinase activation by incorporating 4-hexylresorcinol.

Silk suture material is primarily composed of silk fibroin and regarded as a non-resorbable material. It is slowly degraded by proteolysis when it is implanted into the body. 4-Hexylresorcinol (4HR) is a well-known antiseptic. In this study, the biodegradability of 4HR-incorporated silk sutures were compared to that of untreated silk sutures and polyglactin 910 sutures, a commercially available resorbable suture. 4HR-incorporated silk sutures exhibited anti-microbial properties. Matrix metalloproteinase (MMP) can digest a wide spectrum of proteins. 4HR increased MMP-2, -3, and -9 expression in RAW264.7 cells. MMP-2, -3, and -9 were able to digest not only silk fibroin but also silk sutures. Consequently, 59.5% of the 4HR-incorporated silk suture material remained at 11 weeks after grafting, which was similar to that of polyglactin 910 degradation (56.4% remained). The residual amount of bare silk suture material at 11 weeks after grafting was 91.5%. The expression levels of MMP-2, -3 and -9 were high in the 4HR-incorporated silk suture-implanted site 12 weeks after implantation. In conclusion, 4HR-treated silk sutures exhibited anti-microbial properties and a similar level of bio-degradation to polyglactin 910 sutures and induced higher expression of MMP-2, -3, and -9 in macrophages.

Atypical granular cell tumor in the maxilla: The first report of primary intraosseous granular cell tumor.

BACKGROUND: Granular cell tumor (GCT) is a benign soft tissue tumor of neural origin and is characterized by eosinophilic granular cells showing positivity for neuronal markers. Herein, we report the first case of primary intraosseous GCT arising in the maxilla of an adolescent girl. METHODS AND RESULTS: A 16-year-old female patient presented with palatal swelling. Radiographic findings revealed a well-defined radiolucent lesion centrally located in the right maxilla. Mass excision was performed, and histopathologic examination showed sheets and cords of eosinophilic granular cells with cellular pleomorphism. Tumor cells were strongly positive for vimentin, S-100 protein, and CD56, and negative for cytokeratin, desmin, smooth muscle actin, and c-kit. High expression of p53 and Ki-67 was found. The final diagnosis was atypical GCT. CONCLUSION: When evaluating an intraosseous radiolucent lesion with histopathologic features of granular cells, clinicians and pathologists should include GCT in the differential diagnosis. © 2016 Wiley Periodicals, Inc. Head Neck 38:E2467-E2470, 2016.

KiSS-1 expression in oral squamous cell carcinoma and its prognostic significance.

Downregulated expression of KiSS-1 has been correlated with tumor progression, metastasis, and patient prognosis in various human malignancies. However, there is no information regarding the expression of KiSS-1 in oral squamous cell carcinoma (OSCC). Our aims were to examine KiSS-1 expression in OSCC tissue samples and cell lines and to determine its prognostic significance. KiSS-1 expression was significantly lower in lymph node (LN) metastases than in primary tumor tissues. Five of six OSCC cell lines showed absence or relatively low expression of KiSS-1. Correlations between KiSS-1 expression and clinicopathological parameters were statistically assessed. There were significant correlations between KiSS-1 expression and LN metastasis (p = 0.007), TNM stage (p = 0.024), and local recurrence (p = 0.012). In the Kaplan-Meier survival analysis, negative KiSS-1 expression significantly correlated with poorer overall survival (OS) and disease-free survival (DFS) (p = 0.000 and 0.000, respectively). Multivariate analysis using Cox regression modeling revealed that KiSS-1 expression was an independent prognostic factor for both OS and DFS (p = 0.001 and 0.000, respectively). Our findings suggested that KiSS-1 downregulation may play a role in tumor progression and metastasis of OSCC and may be a reliable biomarker for predicting clinical outcome in OSCC.

Geriatric oral lesions: A multicentric study.

AIM: To carry out an oral biopsy survey in geriatric patients from the participating institutions. METHODS: The biopsy records of the participating institutions were reviewed for oral lesions from patients aged 65 years and older diagnosed from 2003 to 2012. Demographic data and the site of the lesions were collected. Histopathological diagnoses were categorized into two categories: non-neoplastic lesions (reactive/inflammatory lesion, cyst, allergic/immunologic disorders, potentially malignant disorders, infection and others) and neoplastic lesions (benign and malignant tumors). Data were analyzed by appropriate statistics using stata11. RESULTS: Of the 76,045 accessioned cases, 11,346 cases (14.92%) were in geriatric patients. The mean age of the patients was 72.98 ± 6.25 years. A total of 5010 cases (44.16%) were diagnosed in males, whereas 6336 cases (55.84%) were diagnosed in females. The male-to-female ratio was 0.79:1. Non-neoplastic lesions outnumbered the neoplastic counterpart. The five most prevalent oral lesions in the geriatric population in the present study in descending order of frequency were squamous cell carcinoma, focal fibrous hyperplasia (irritation fibroma), radicular cyst, osteomyelitis and epithelial dysplasia, respectively. The site of predilection was labial/buccal mucosa, followed by gingiva, mandibular bone, tongue and maxillary bone, respectively. CONCLUSIONS: The geriatric oral lesions from the present study showed a similar trend with studies based on histopathological data, but different from the studies based on clinical data. This study also shed more light on potentially malignant disorders, as well as benign and malignant tumors.

Thymosin ß4 induces proliferation, invasion, and epithelial-to-mesenchymal transition of oral squamous cell carcinoma.

The epithelial-to-mesenchymal transition (EMT) plays a vital role in carcinogenesis, invasion, and metastasis of many epithelial tumors including oral squamous cell carcinoma (OSCC), a common malignancy of the head and neck. However, the functional role of the actin-sequestering protein thymosin ß4 (Tß4) in the EMT in OSCCs remains unclear. Thus, we investigated whether overexpression of Tß4 could induce in vitro tumorigenesis such as cell proliferation and anchorage independency and an EMT-like phenotype in OSCCs. Also, we examined whether it affects invasiveness and cell motility-associated signaling molecules. Tß4-overexpressing OSCCs, SCC-15_Tß4 and SCC-25_Tß4, enhanced cell proliferation and colony formation. In addition, we observed that Tß4 overexpression induced an EMT-like phenotype, accompanied by a decrease in expression of the epithelial cell marker E-cadherin and an increase in expression of mesenchymal cell markers vimentin and N-cadherin. Also, the expression level of Twist1, an EMT-inducing transcription factor, was significantly enhanced in SCC-15_Tß4 and SCC-25_Tß4 cells. Tß4 overexpression augmented in vitro invasion and MMP-2 activity and enhanced the phosphorylation of paxillin and cortactin and expression of LIMK1. Taken together, these results suggest that Tß4 overexpression could be one of the causes of tumorigenesis and progression in OSCCs. Further investigation on the Tß4 molecule would encourage the development of specific targets for cancer treatment.

Chondrosarcoma of the temporomandibular joint: a case report and review of the literature.

OBJECTIVE: Chondrosarcoma is the second most common sarcoma arising in the bone, but it rarely involves the temporomandibular joint (TMJ). To date, 30 cases of TMJ chondrosarcoma have been reported in the English literature, and the authors report an additional case arising from a cystic lesion in a 60-year-old female patient. CLINICAL PRESENTATION: The clinical and radiological diagnosis of the lesion was initially synovial cyst, and periodic check-ups were done after aspiration of the lesion. After three years, the patient perceived swelling of the lesion, and surgical excision was performed. The final diagnosis was grade I chondrosarcoma. CONCLUSION: When clinicians detect a cystic lesion in the radiographic imaging of the TMJ, chondrosarcoma should be included in the differential diagnosis. In addition, computed tomography (CT) as well as magnetic resonance imaging (MRI) is recommended for the accurate diagnosis and proper preoperative planning in TMJ chondrosarcoma.

The Effect of a Combination of Implant Controller and Handpiece from Different Manufacturers on the Torque Value.

PURPOSE: To determine the accuracy of applied torque of different implant controller and handpiece combinations by using an electronic torque gauge. MATERIALS AND METHODS: Four combinations of the following devices were tested: Surgic XT controller (NSK), XIP10 controller (Saeshin), X-SG20L handpiece (NSK), CRB26LX handpiece (Saeshin). For five torque settings, 30 measurements were recorded at 30 revolutions per minute by using an electronic torque gauge fixed to jigs, and means were calculated. RESULTS: Applied torques were generally higher than the set torque of 10 and 20 Ncm and lower than the set values of 40 and 50 Ncm. The average torque deviations differed significantly among the combinations (P < .05). At 10 and 20 Ncm, the Surgic XT/X-SG20L combination yielded the closest value to the intended torque, followed by the XIP10/X-SG20L combination. At 30 Ncm, the XIP10/X-SG20L combination showed the nearest value. At 40 Ncm, the Surgic XT/X-SG20L, XIP10/CRB26LX, and XIP10/X-SG20L combinations showed deviations within 10%. At 50 Ncm, all the combinations showed lower applied torque than the set value. Large standard deviations were observed in the Surgic XT/CRB26LX (13.288) and Surgic XT/X-SG20L (7.858) combinations. CONCLUSION: Different combinations of implant controllers and handpieces do not generate significant variations in applied torque. The actual torque varies according to the torque setting. It is necessary to calibrate devices before use to reduce potentially problematic torque.

The potential of interleukin 12 receptor beta 2 (IL12RB2) and tumor necrosis factor receptor superfamily member 8 (TNFRSF8) gene as diagnostic biomarkers of oral lichen planus (OLP).

OBJECTIVE: This study evaluated the potential of interleukin 12 receptor beta 2 and tumor necrosis factor receptor superfamily member 8 as diagnostic biomarkers of oral lichen planus (OLP). MATERIALS AND METHODS: The mRNA expression of IL12RB2 and TNFRSF8 in FFPE OLP samples (OLP group, n = 38) were investigated with quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) analysis and compared to those of chronic non-specific mucositis (Non-OLP group, n = 25) and normal mucosa (Normal group, n = 18). Predictive modeling of the expression of IL12RB2 and TNFRSF8 was constructed using support vector machine (SVM), random forest (RF), linear discriminant analysis (LDA), neural network (NN) and naive Bayes (NB) methods. RESULTS: Normalized expression of IL12RB2 in the OLP group (3.78 ± 1.67) was significantly higher than the Normal group (1.97 ± 1.12), but lower than the Non-OLP group (6.86 ± 1.67). TNFRSF8 gene expression in the OLP group (7.46 ± 1.51) was significantly higher than the Normal group (2.90 ± 1.61), but no significant difference was found between the OLP and Non-OLP groups. The ratio of IL12RB2/TNFRSF8 in the OLP group (0.52 ± 0.23) was significantly lower than the Normal group (0.74 ± 0.39) and the Non-OLP group (1.07 ± 0.38). In the predictive modeling, the area under receiver operating characteristic (ROC) curves (AUC) ranged from 0.83-0.92 and their accuracy was higher than 0.75 in all methods. CONCLUSIONS: The IL12RB2/TNFRSF8 ratio can be a useful diagnostic tool for OLP.

Geometric and electronic structure and magnetic properties of Fe-Au nanoalloys: insights from ab initio calculations.

We have performed density functional theory (DFT) based calculations of Fe-Au nanoalloys containing 113 atoms, Fe(x)Au(113-x) (x = 23, 56, 90), to determine their preferred geometric structure and the ensuing electronic structural and magnetic properties. We find that these nanoalloys prefer the formation of a core-shell structure and the Fe core maintains almost a constant magnetic moment of ∼2.8 µ(B) regardless of the Fe content, which is 27% enhancement from the bulk value and in qualitative agreement with some previous results. The local magnetic moment of Fe atoms is well correlated with the local coordination of the Fe atoms. Furthermore, the enhancement of the magnetic moment may be traced to charge depletion from the Fe atoms in the core to the Au atoms in the shell. The preference for the core-shell structure over one with segregated Fe and Au parts could be the low surface tension at the Fe-Au interface, which is larger for the core-shell structure, and can be attributed to strong Fe-Au interfacial interaction as a result of large charge transfer at the interface.

The role of p300 in the tumor progression of oral squamous cell carcinoma.

BACKGROUND: EP300 gene encoding p300 is a candidate tumor suppressor gene. This study investigated p300 expression and gene alteration in oral squamous cell carcinoma (OSCC) specimens to assess its role in OSCC development. METHODS: Genomic DNA extracted from 13 human OSCC cell lines and 40 OSCC patient specimens was subjected to methylation-specific PCR and exon sequencing. Immunohistochemical staining with primary antibodies against p300 and p53 was performed in 48 patients with OSCC. We analyzed the association between the data and clinicopathological factors of OSCC patients. RESULTS: Methylation-specific PCR revealed that the EP300 promoter region was not hypermethylated in OSCC. Only one cell line demonstrated a point mutation at exon 31. On immunohistochemical examination, patients with metastatic lymph nodes (P = 0.009) and advanced clinical stage (P = 0.046) tended to show increased expression of p300. There was no statistically significant relationship between p300 expression and p53 accumulation in OSCC tissue samples. Patient survival was not correlated with p300 expression. CONCLUSIONS: EP300 is not a tumor suppressor gene because there was neither epigenetic inactivation of the gene nor a mutation resulting in functional impairment. Based on p300 overexpression and its association with clinical factors in patients with OSCC, it is likely that p300 itself or one of its target genes plays a key role in the aggressive phenotypes of OSCC.

Structural and electronic properties of micellar Au nanoparticles: size and ligand effects.

Gaining experimental insight into the intrinsic properties of nanoparticles (NPs) represents a scientific challenge due to the difficulty of deconvoluting these properties from various environmental effects such as the presence of adsorbates or a support. A synergistic combination of experimental and theoretical tools, including X-ray absorption fine-structure spectroscopy, scanning transmission electron microscopy, atomic force microscopy, and density functional theory was used in this study to investigate the structure and electronic properties of small (∼1-4 nm) Au NPs synthesized by an inverse micelle encapsulation method. Metallic Au NPs encapsulated by polystyrene 2-vinylpiridine (PS-P2VP) were studied in the solution phase (dispersed in toluene) as well as after deposition on γ-Al2O3. Our experimental data revealed a size-dependent contraction of the interatomic distances of the ligand-protected NPs with decreasing NP size. These findings are in good agreement with the results from DFT calculations of unsupported Au NPs surrounded by P2VP, as well as those obtained for pure (ligand-free) Au clusters of analogous sizes. A comparison of the experimental and theoretical results supports the conclusion that the P2VP ligands employed to stabilize the gold NPs do not lead to strong distortions in the average interatomic spacing. The changes in the electronic structure of the Au-P2VP NPs were found to originate mainly from finite size effects and not from charge transfer between the NPs and their environment (e.g., Au-ligand interactions). In addition, the isolated ligand-protected experimental NPs only display a weak interaction with the support, making them an ideal model system for the investigation of size-dependent physical and chemical properties of structurally well-defined nanomaterials.

Plasmablastic lymphoma of the oral cavity in a human immunodeficiency virus-negative patient: a case report with literature review.

Plasmablastic lymphoma (PBL) is an aggressive diffuse large B-cell lymphoma variant that is most frequently observed in the oral cavity of human immunodeficiency virus (HIV)-infected individuals. However, in recent years, some cases have emerged in patients without HIV infection and involve other sites like stomach, lung, nasal cavity, and jejunum. We report a rare case of PBL in the maxillary anterior area of a 62-year-old man without HIV infection. The tumor cells were characterized by non-cohesive round or oval shape cells with eccentrically-placed nuclei with a prominent perinuclear halo. Immunohistochemical studies showed that the tumor cells were strongly positive for MUM1, VS38c, VMT, and κ light chain, focally positive for LCA and CD79a, and negative for CD3, CD20, CD56, λ light chain, CK-pan, EMA, and HMB45. The patient was treated with chemotherapy using cyclophosphamide, doxorubicin, vincristine, and prednisone. The lesion showed partial remission.

Hypothetical pathogenesis of eosinophilic infiltration in Langerhans cell histiocytosis of the jaw.

OBJECTIVE: The present study investigated the densities of mast cells and CCL-11/eotaxin-1 expression of tumor cells in Langerhans cell histiocytosis (LCH) of the jaw. STUDY DESIGN: Eleven LCH cases arising in the jaws were selected. We evaluated eotaxin-1 expression in LCH cells via immunohistochemical staining. Toluidine blue was used to stain mast cells, with 20 periapical granuloma specimens serving as the control group. RESULTS: In all 7 patients with multifocal LCH, jaw lesions were the earliest manifestation. Toluidine blue staining revealed that most of the mast cells involved in LCH were degranulated, and the number of mast cells in LCH lesions was not significantly higher than in periapical granulomas. Upon immunohistochemical examination, all patients but one showed positivity for eotaxin-1 in LCH cells. CONCLUSION: This preliminary study suggests that eotaxin-1 expression in LCH cells may contribute to eosinophilic infiltration. Further studies of chemokine-receptor interactions will be needed to confirm this.

Rationale for the higher reactivity of interfacial sites in methanol decomposition on Au13/TiO2(110).

Interfacial and perimeter sites have been known for their high activity in various reactions on supported gold nanoparticles. We find that the higher activity of interfacial sites in Au13/TiO2(110) toward methanol decomposition originates from charge-transfer-induced Coulomb interaction among the gold, reactant, and reducible TiO2 support, brought about through the formation of an ionic O-Au bond between gold and methoxy in such sites, which turns the participating perimeter gold atom cationic. A direct result of such charge-transfer-induced repulsive interaction between cationic gold and positively charged C moiety of methoxy is activation of the positively charged C moiety of methoxy, as manifested by the pronounced elongation of O-C bond length and the tilting of the methoxy axis, which facilitate reaction of methoxy through C-H scission with the bridge oxygen atoms that are readily available from the reducible support. More generally, our proposed mechanism for the reactivity of the gold/TiO2 interface should hold for oxidation of organic molecules with the structure of R-O-R', where R and R' are (saturated) hydrocarbons.

A giant radiopaque mass in the masticatory space.

A 2-year-old boy presented with a giant mass in the masticatory space. The mass exhibited a lobulating ossification, with no attachment to the adjacent normal bone. An enucleation was performed under the tentative diagnosis of extra-articular synovial chondromatosis, benign ossifying neoplasm, non-neoplastic heterotopic ossification, or low-grade malignancy. Upon microscopic examination, the excised mass was composed of multiple osteocartilaginous areas. We hereby present detailed clinicopathological findings.

Histopathological features of bisphosphonate-associated osteonecrosis: findings in patients treated with partial mandibulectomies.

The present study investigated the histopathologic and radiographic features of stage 3 bisphosphonate-associated osteonecrosis of the jaw (BAONJ) in patients who were treated with partial mandibulectomies. Bisphosphonates had been orally administered to 10 patients with osteoporosis and intravenously administered to 1 patient with metastatic carcinoma. On radiographic images, massive osteolysis and periosteal bone formations were conspicuous, and a thin mandibular cortical width was observed in 5 of 10 osteoporosis patients despite the previous use of bisphosphonate. Microscopically, the mandibulectomy specimens of the patients could be divided into 4 distinct layers. Although there were few differences in overall histologic features between BAONJ and chronic suppurative osteomyelitis, a notable number of osteoclasts were found detached from the bony trabeculae in BAONJ.

Comparative immunohistochemical study of ameloblastoma and ameloblastic carcinoma.

OBJECTIVE: Ameloblastic carcinoma combines the histologic features of ameloblastoma with cytologic atypia, regardless of whether it has metastasized. Because of its rarity, there are few immunoprofile studies of ameloblastic carcinoma and few comparative studies of ameloblastic carcinoma and ameloblastoma. In this study, we compared the expression levels of cytokeratins (CKs), matrix metalloproteinases (MMPs), and Ki-67 between ameloblastoma and ameloblastic carcinoma, and assessed the usefulness of these markers for differentiating the tumors. STUDY DESIGN: We assessed CK7, CK14, CK18, CK19, MMP-2, MMP-9, and Ki-67 expression by immunohistochemistry in 10 cases of ameloblastoma and 7 cases of ameloblastic carcinoma and then compared expression patterns between the 2 groups. RESULTS: Immunostaining for CK14 and CK19 was diffuse and strongly positive in both tumor types, but staining for CK7 was focally positive in only 1 case of ameloblastoma and absent in all cases of ameloblastic carcinoma. However, there was a significant difference in CK18 expression between the 2 tumors (P = .000). Whereas 80% of ameloblastomas showed negative reactivity for CK18, most cases of ameloblastic carcinomas showed a moderate to strong intensity of immunostaining for CK18. Regarding the expression of MMPs, there were significant differences in parenchymal MMP-2 and stromal MMP-9 expression between the 2 tumors. Compared to ameloblastoma, ameloblastic carcinoma showed significantly strong expression of MMP-2 in parenchymal cells (P = .001) and MMP-9 in stromal cells (P = .013). However, there were no differences in MMP-2 expression of stromal cells and MMP-9 expression of parenchymal cells between ameloblastoma and ameloblastic carcinoma. The mean Ki-67 labeling index (LI) of ameloblastic carcinomas was 17.21%, which was significantly higher than that of ameloblastomas (3.57%; P = .002). CONCLUSIONS: The significant expression of CK18, parenchymal MMP-2, stromal MMP-9, and Ki-67 could provide useful markers for differentiating ameloblastic carcinoma from ameloblastoma.