Raorao Wang

Toxicity of carbon nanotubes.

Carbon nanotubes (CNTs) find their extensive application as a promising material in medicine due to unique characteristics. However, such materials have been accompanied with potentially hazardous effects on human health. The toxicity of CNTs may vary depending on their structural characteristics, surface properties and chemical composition. To gain insight into the toxicity of CNTs in vivo and in vitro, we summarize contributing factors for the toxic effects of CNTs in this review. In addition, we elaborate on the toxic effects and mechanisms in target sites at systemic, organic, cellular, and biomacromolecule levels. Various issues are reported to be effected when exposed to CNTs including (1) blood circulation, (2) lymph circulation, (3) lung, (4) heart, (5) kidney, (6) spleen, (7) bone marrow, and (8) blood brain barrier. Though there have been published reports on the toxic effects of CNTs to date, more studies will still be needed to gain full understanding of their potential toxicity and underlying mechanisms.

Recent advances in cell sheet technology for periodontal regeneration.

Tissue engineering has yielded several successes in early clinical trials of regenerative medicine with grafting therapeutic cells seeded into biodegradable scaffolds. However this conventional cell delivery method has limited the fields progress. In recent decades, we have developed a novel cell transferring method, cell sheet technology that allows for controlled attachment and detachment of cells via simple temperature variations of a surface-intelligent temperatureresponsive polymer:poly (N-isopropylacrylamide). It has been widely applied to create functional tissue sheets with cells derived from various tissues to treat a wide range of diseases. Periodontal cell sheets non-invasively harvested from temperature- responsive culture surfaces have been successfully manufactured, resulting in communicative multilayered constructs. Transplantation of cell sheets onto periodontal defects has improved bone and tissue regeneration in animal models and humans and shows low immunogenicity. In this review, we summarize the recent advances of techniques in cell sheet engineering and its application for periodontal regeneration.

PAX9 polymorphism and susceptibility to sporadic non-syndromic severe anodontia: a case-control study in southwest China

Our research aimed to look into the clinical traits and genetic mutations in sporadic non-syndromic anodontia and to gain insight into the role of mutations of PAX9, MSX1, AXIN2 and EDA in anodontia phenotypes, especially for the PAX9. Material and Methods: The female proband and her family members from the ethnic Han families underwent complete oral examinations and received a retrospective review. Venous blood samples were obtained to screen variants in the PAX9, MSX1, AXIN2, and EDA genes. A case-control study was performed on 50 subjects with sporadic tooth agenesis (cases) and 100 healthy controls, which genotyped a PAX9 gene polymorphism (rs4904210). Results: Intra-oral and panoramic radiographs revealed that the female proband had anodontia denoted by the complete absence of teeth in both the primary and secondary dentitions, while all her family members maintained normal dentitions. Detected in the female proband were variants of the PAX9 and AXIN2 including A240P (rs4904210) of the PAX9, c.148C>T (rs2240308), c.1365A>G (rs9915936) and c.1386C>T (rs1133683) of the AXIN2. The same variants were present in her unaffected younger brother. The PAX9 variations were in a different state in her parents. Mutations in the MSX1 and EDA genes were not identified. No significant diferences were found in the allele and genotype frequencies of the PAX9 polymorphism between the controls and the subjects with sporadic tooth agenesis. Conclusions: These results suggest that the association of A240P with sporadic tooth agenesis still remains obscure, especially for different populations. The genotype/phenotype correlation in congenital anodontia should be verified.

Review of and Perspectives on the Toxicology of Graphene-based Materials

Graphene possesses a wide range of potential biomedical applications because of the unique physical and chemical properties. However, the side effects of grapheme and its derivatives on a number of biological models even on human body are still not very clear. Therefore, to properly assess the potential risk of grapheme and its derivatives, we summarize the current state of academic knowledge on their toxicity.

DNA methylation is critical for tooth agenesis: implications for sporadic non-syndromic anodontia and hypodontia

Hypodontia is caused by interactions among genetic, epigenetic, and environmental factors during tooth development, but the actual mechanism is unknown. DNA methylation now appears to play a significant role in abnormal developments, flawed phenotypes, and acquired diseases. Methylated DNA immunoprecipitation (MeDIP) has been developed as a new method of scanning large-scale DNA-methylation profiles within particular regions or in the entire genome. Here, we performed a genome-wide scan of paired DNA samples obtained from 4 patients lacking two mandibular incisors and 4 healthy controls with normal dentition. We scanned another female with non-syndromic anodontia and her younger brother with the same gene mutations of the PAX9,MSX1,AXIN2 and EDA, but without developmental abnormalities in the dentition. Results showed significant differences in the methylation level of the whole genome between the hypodontia and the normal groups. Nine genes were spotted, some of which have not been associated with dental development; these genes were related mainly to the development of cartilage, bone, teeth, and neural transduction, which implied a potential gene cascade network in hypodontia at the methylation level. This pilot study reveals the critical role of DNA methylation in hypodontia and might provide insights into developmental biology and the pathobiology of acquired diseases.

The Correlations between Health-Related Quality of Life Changes and Pain and Anxiety in Orthodontic Patients in the Initial Stage of Treatment

This study aimed to assess generic health-related quality of life (HRQoL), pain intensity, and anxiety levels and the relationship between the three aspects in healthy young Chinese orthodontic patients in the early stage of orthodontic treatment. We enrolled 252 eligible participants (10–29 years old) to complete validated Chinese versions of questionnaires, including the State-Trait Anxiety Inventory (S-AI), the visual analogue scale (VAS), and the Short-Form 36-Item Health Survey (SF-36) at baseline and on days 1, 2, 3, 7, 14, and 30 after initial archwire placement (SF-36 only at baseline and day 30). The response rate was 96% (243 of 252). SF-36 had moderate reliability (Cronbachs alpha coefficient exceeding 0.7, good fit on day 30). Statistical significant changes were observed in physical function (P < 0.01), body pain (P = 0.01), and general health (P < 0.01) domains. Spearman correlation coefficients for SF-36 with S-AI were −0.131~−0.515 (P < 0.05); SF-36 with VAS were −0.141~−0.273 (P < 0.05), indicating significant but moderate negative correlations between HRQoL and pain/anxiety. Overall, the application of SF-36 in assessing HRQoL is reluctantly suitable for young Chinese orthodontic patients in the early stage of orthodontic treatment. Early treatment-related pain and anxiety are important factors in HRQoL.

Expression and Function of PPARs in Cancer Stem Cells.

Cancer stem cells (CSCs) are cancer cells with characteristics of stem cells, especially the ability to arise to all types of cell in a particular cancer tissue. With the capacity to generate multiple types of cancer cells, CSCs are proposed as primary impetus for tumor initiation and metastases and are suggested as potential therapeutic targets for anti-cancer treatment. Peroxisome-proliferator-activated receptors (PPARs) are a subset of multifunctional transcription factors which play a pivotal role in cancer development and tumorigenesis. PPARs are also reported to be involved in the modulation of the epithelial-mesenchymal transition (EMT) process in CSC initiation and in the regulation of CSC functions. However, the exact mechanisms remain unknown. Herein, we review the latest evidence on the regulatory effects and mechanisms of PPARs in CSC formation and function, and evaluate the prospects of PPARs as a target for cancer treatment.

Effect of estrogen deficiency on implant osseointegration in dogs.

PURPOSE This study investigated the effect of the absence of estrogen on the process of implant osseointegration in the jaws of beagle dogs. MATERIALS AND METHODS Of eight beagle dogs, four underwent bilateral ovariectomy (OVX), and the other four constituted a control group. Twelve weeks postsurgery, XiVE implants (Dentsply) were placed in the second premolar site in the mandible and in the canine site in the maxilla. Zero, 4, 8, 12, and 16 weeks after implant placement, implant stability quotients (ISQs) were measured by resonance frequency analysis (RFA). RESULTS The blood estrogen levels 12 weeks postsurgery were 5.8 ± 1.8 pg/mL in the OVX group and 37.0 ± 2.9 pg/mL in the control group, which represents a significant decrease (P < .01). The ISQ of maxillary implants in the OVX group 12 weeks after implant placement was 64.5 ± 1.7, and in the control group it was 74.3 ± 1.5; the ISQ was significantly reduced in the OVX group (.01 < P < .05). CONCLUSION The results of this study indicate that the absence of estrogen induced by OVX in beagle dogs could reduce osseointegration around maxillary implants but has little influence in the mandible.

Development course and an application strategy for induced pluripotent stem cells in regenerative medicine.

In 2006, Takahashi and Yamanaka first established induced pluripotent stem cells (iPScs). Since then, numerous improvements have been made in the fields of stem cell research, drug research, modelling of diseases, and the treatment of degenerative diseases. Recently, there has been increasing research involving small molecules for evaluating the efficiency of iPSc generation and reducing the risks of heredity as well as oncogenous problems. However, the molecular mechanisms of iPScs remain to be further explored, to meet the demands of practical applications. With a better understanding of degenerative diseases, more complex treatment strategies for novel regenerative medicine are anticipated, and iPSc technology offers an available pathway. This review focuses on the development and application of iPScs.