Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 783
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Talanta ; 206: 120183, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514879

RESUMO

Mobility capillary electrophoresis (MCE) was developed previously in our group, which has the capabilities of ion separation and biomolecule hydrodynamic radius analysis. The coupling of MCE with mass spectrometry (MS) would greatly improve complex sample identification capability as well as system detection sensitivity. In the present study, a simple and robust ionization source, named as straight nano-electrospray ionization (nanoESI) source was developed, which was applied to couple MCE with MS. A stainless-steel needle attached directly at the end of an MCE capillary was used as the nanoESI emitter, and the connection between this emitter to the liquid flow in the MCE separation channel was established through a liquid bridge. After optimization, this straight nanoESI source enhanced the ion signal intensity by ~10 times when compared with a commercial nanoESI source. The MCE-straight nanoESI-MS system was also characterized in terms of mixture separation and peptide hydrodynamic radius measurements. Compared to our previous work when a UV detector was used in a commercial Lumex CE system (model Capel 105 M, St. Petersburg, Russia), peptides with much lower concentrations could be analyzed (from ~1 mg/mL to ~20 µg/mL) in terms of radius measurement.

2.
Nanomedicine (Lond) ; 14(20): 2679-2696, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31668141

RESUMO

Plastic surgery encompasses a broad spectrum of reconstructive challenges and prides itself upon developing and adopting new innovations. Practice has transitioned from microsurgery to supermicrosurgery with a possible future role in even smaller surgical frontiers. Exploiting materials on a nanoscale has enabled better visualization and enhancement of biological processes toward better wound healing, tumor identification and viability of tissues, all cornerstones of plastic surgery practice. Recent advances in nanomedicine and biomimicry herald further reconstructive progress facilitating soft and hard tissue, nerve and vascular engineering. These lay the foundation for improved biocompatibility and tissue integration by the optimization of engineered implants or tissues. This review will broadly examine each of these technologies, highlighting areas of progress that reconstructive surgeons may not be familiar with, which could see adoption into our armamentarium in the not-so-distant future.

3.
Medicine (Baltimore) ; 98(44): e17685, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31689790

RESUMO

To compare imaging indicators and clinical effects of extreme lateral interbody fusion (XLIF) using allogenic bone, autologous bone marrow + allogenic bone, and rhBMP-2 + allogenic bone as bone graft materials in the treatment of degenerative lumbar diseases.This was a retrospective study of 93 patients with lumbar interbody fusion who underwent the extreme lateral approach from May 2016 to December 2017. According to the different bone graft materials, patients were divided into allogenic bone groups (group A, 31 cases), rhBMP-2 + allogenic bone (group B, 32 cases), and autologous bone marrow + allogenic bone (group C, 30 cases). There were no significant differences in gender, age, lesion segment, preoperative intervertebral space height, and preoperative Oswestry Dysfunction Index (ODI) and visual analogue scale (VAS) scores among the 3 groups (P > .05). Intervertebral space height, bone graft fusion rate, and ODI and VAS scores were compared immediately after surgery, and at 3, 6, and 12 months after surgery.All groups were followed up for 12 months. The intervertebral space height was significantly higher in the 3 groups immediately after surgery and at 3, 6, and 12 months after surgery, in comparison to before surgery (P < .05). There was no significant difference in the intervertebral space height among the 3 groups immediately after surgery and at 3, 6, and 12 months after surgery (P > .05). The fusion rate of group B and C was higher than that of groups A at 3, 6, and 12 months after surgery (P < .05). In the 3 groups, the VAS and ODI scores at 3, 6, and 12 months after surgery were significantly improved compared with the preoperative scores (P < .05). The VAS and ODI scores in groups B and C were significantly higher than those in group A (P < .05), but there was no significant difference between groups B and C (P > .05).The rhBMP-2 + allograft bone combination had good clinical effects and high fusion rate in XLIF.

4.
J Mass Spectrom ; 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31697856

RESUMO

Current miniature mass spectrometers mainly focus on the analyses of organic and small biological molecules. In this study, we explored the possibility of developing high resolution miniature ion trap mass spectrometers for whole protein analysis. Theoretical derivation, GPU assisted ion trajectory simulation and initial experiments on home-developed "brick" mass spectrometer were carried out. Results show that ion-neutral collisions have smaller damping effect on large protein ions, and a higher buffer gas pressure should be applied during ion trap operations for protein ions. As a result, higher pressure ion trap operation not only benefit instrument miniaturization, but also improve mass resolution of protein ions. Dynamic mass scan rate and generation of low charge state protein ions are also found to be helpful in terms of improving mass resolutions. Theory and conclusions found in this work are also applicable in the development of benchtop mass spectrometers.

5.
Nat Commun ; 10(1): 5114, 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31704972

RESUMO

Triple-negative breast cancer (TNBC), which lacks estrogen receptor α (ERα), progesterone receptor, and human epidermal growth factor receptor 2 (HER2) expression, is closely related to basal-like breast cancer. Previously, we and others report that cyclin E/cyclin-dependent kinase 2 (CDK2) phosphorylates enhancer of zeste homolog 2 (EZH2) at T416 (pT416-EZH2). Here, we show that transgenic expression of phospho-mimicking EZH2 mutant EZH2T416D in mammary glands leads to tumors with TNBC phenotype. Coexpression of EZH2T416D in mammary epithelia of HER2/Neu transgenic mice reprograms HER2-driven luminal tumors into basal-like tumors. Pharmacological inhibition of CDK2 or EZH2 allows re-expression of ERα and converts TNBC to luminal ERα-positive, rendering TNBC cells targetable by tamoxifen. Furthermore, the combination of either CDK2 or EZH2 inhibitor with tamoxifen effectively suppresses tumor growth and markedly improves the survival of the mice bearing TNBC tumors, suggesting that the mechanism-based combination therapy may be an alternative approach to treat TNBC.

6.
Dent Mater ; 2019 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-31727445

RESUMO

OBJECTIVES: To evaluate two-body wear of three zirconia ceramics stabilized with 3, 4 and 5mol% yttria and to compare their wear behavior with that of a lithium-disilicate glass-ceramic. METHODS: Sixteen rectangular-shaped specimens made from three grades of zirconia ceramics and a lithium-disilicate glass-ceramic were polished and dynamically loaded in a chewing simulator (2kg vertical load, 2.1Hz) under water at 90°C for 1.2×106 cycles (about 7 days) in the ball-on-plate mode against steatite antagonists. Surface roughness was measured before and after wear testing. Wear tracks were scanned with a non-contact 3D profilometer and super-impositions were used to determine wear loss of the antagonists. Wear surfaces were imaged by SEM. XRD and micro-Raman spectroscopy were used to characterize phase transformation and stress status in the worn and unworn areas of the zirconia ceramics. RESULTS: Independent of fracture toughness, strength and aging-susceptibility, the three zirconia ceramics showed a similar and limited amount of wear (∼10µm in depth) and were more wear-resistant than the lithium-disilicate glass-ceramic (∼880µm in depth). Abrasive wear without obvious cracks was observed for all investigated zirconias, whereas the glass-ceramic with a lower fatigue threshold and high susceptibility to surface dissolution exhibited significant abrasion, fatigue and corrosion wear. All three zirconia ceramics yielded a lower antagonist wear than the glass-ceramic and no significant differences were found between the zirconia ceramics. SIGNIFICANCE: In the context of this study, high-translucent zirconia ceramics stabilized with a higher yttria content, recently introduced in the dental field, were as wear-resistant and antagonist-friendly as conventional high-strength zirconia and suitable for monolithic restorations.

7.
Langmuir ; 2019 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-31742409

RESUMO

Valinomycin, a cyclic peptide, was incorporated into a biomimetic lipid membrane tethered (tBLM) to the surface of a gold (111) electrode. Electrochemical Impedance Spectroscopy (EIS) was used to study the ionophore properties of the peptide and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) was used to study the conformation and orientation of valinomycin in the membrane. The combination of these two techniques provided unique information about the ionophore mechanism where valinomycin transports ions across the membrane by creating a complex with potassium ions and forming an ion pair with a counter anion. The ion pair resides within the hydrophobic fragment of the membrane and adopts a small angle of ~22o with respect to the surface normal. This novel study provides new insights explaining the valinomycin ion transport mechanism in model biological membranes.

8.
Zootaxa ; 4604(2): zootaxa.4604.2.5, 2019 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-31717192

RESUMO

Two species of the mite family Celaenopsidae, Pleuronectocelaeno barbara Athias-Henriot, 1959 and Schizocyrtillus fuzhouensis sp. nov., were recorded in China. Specimens were collected in bark and rotten wood on Pinus massoniana Lamb. in Sanming city and Fuzhou city, respectively. Information on current distribution, host association and morphological diagnostics of these two mites is provided.


Assuntos
Ácaros e Carrapatos , Ácaros , Animais , China , Pinus
9.
Cell Rep ; 29(9): 2579-2589.e4, 2019 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-31775029

RESUMO

CRISPR-Cas9 is an adaptive immune system for prokaryotes to defend against invasive genetic elements such as phages and has been used as a powerful tool for genome editing and modulation. To overcome CRISPR immunity, phages encode anti-CRISPR proteins (Acrs) to inhibit Cas9, providing an efficient "off-switch" tool for Cas9-based applications. Here, we characterized AcrIIA5, which is a Cas9 inhibitor discovered in a virulent phage of Streptococcus thermophilus. We found that AcrIIA5 is a potent and broad-spectrum inhibitor of CRISPR-Cas9, which can inhibit diverse Cas9 orthologs of type II-A, type II-B, and type II-C. AcrIIA5 inhibits Cas9 by preventing DNA target cleavage, but DNA target binding of Cas9 is unaffected. Importantly, it can affect the activity of the RuvC nuclease domain of Cas9 independent of the HNH nuclease domain. Our work expands the diversity of the inhibitory mechanisms used by Acrs and provides the guidance for developing controlling tools in Cas9-based applications.

10.
ACS Appl Mater Interfaces ; 11(44): 41238-41244, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31609577

RESUMO

Metal nanoparticles have been recognized and widely explored as unique catalysts for carbon-carbon coupling reactions. However, due to their extreme tendency to agglomeration, the generation and stabilization of metal nanoparticles in a porous matrix is an important research field. Herein, novel mesoporous phenolic resin-supported palladium nanoparticles (Pd@NH2-MPRNs) were prepared via direct anionic exchange followed by gentle reduction by using primary amine-functionalized ordered mesoporous phenolic resin as the support. The obtained Pd@NH2-MPRN material still possessed large surface area and ordered two-dimensional hexagonal mesoporous structure. Meanwhile, uniform and well-dispersed palladium nanoparticles were formed in the mesoporous channels, which could be attributed to an efficient complexation and stabilization effect derived from the primary amine groups. As a result, it can promote Suzuki coupling of less activated aromatic bromides to various biaryls in water with high conversion and selectivity. This excellent performance was attributed to small particle sizes, ordered mesopores, and a hydrophobic pore surface, which resulted in the decreased diffusion limitation and the increased active site accessibility. It is noted that it is competitive with the best palladium catalysts known for water-medium Suzuki coupling reaction, and it can be reused at least seven times without significant reduction in the catalytic efficiency, showing a good recyclability. Therefore, this work provides a new potential platform for designing and fabricating robust ordered mesoporous-polymer-supported metal nanoparticles for various catalytic applications.

11.
Int J Mol Sci ; 20(19)2019 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-31569563

RESUMO

Both the presence of, and the important contribution to growth and development made by TCP transcription factors, have been established in various plant species. Here, a TCP4 homolog isolated from Chrysanthemum nankingense was shown to be more strongly transcribed in the diploid than in the autotetraploid form of the species. CnTCP4 was shown to encode a member of the class II TCP family and to be transcribed most strongly in the leaf and ligulate flowers. Its transcription was found to be substantially inhibited by spraying the plant with the synthetic cytokinin 6-benzylaminopurine. The transient expression of CnTCP4 in onion epidermal cells showed that its product localized to the nucleus, and a yeast one hybrid assay suggested that its product had transcriptional activation ability. The constitutive expression of CnTCP4 in fission yeast suppressed cell proliferation, inducing the formation of longer and a higher frequency of multinuclated cells. Its constitutive expression in Arabidopsis thaliana reduced the size of the leaves. The presence of the transgene altered the transcription of a number of cell division-related genes. A yeast one hybrid assay identified a second TCP gene (CnTCP2) able to interact with the CnTCP4 promoter. A transient expression experiment in Nicotiana benthamiana leaves showed that CnTCP2 was able to activate the CnTCP4 promoter. Like CnTCP4, CnTCP2 was shown to encode a member of the class II TCP family, to be transcribed most strongly in the leaf and ligulate flowers, and to be suppressed by exogenous 6-benzylaminopurine treatment. The CnTCP2 protein also localized to the nucleus, but had no transcriptional activation ability. Its constitutive expression in A. thaliana had similar phenotypic consequences to those induced by CnTCP4.

12.
Clin Anat ; 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31576590

RESUMO

Forefoot defects caused by accidents are very common, but their reconstruction remains a substantial challenge for plastic surgeons. The purpose of this study is to determine the anatomical structure of the first metatarsal proximal perforator-based flap and to propose its clinical application. The study was divided into two parts: an anatomical study and a clinical application. Thirty preserved lower limbs injected with red latex were chosen for observation, and the following were recorded: the course and distribution of the medialis dorsalis pedis cutaneous nerve; the origin, course, branching and distribution of the first metatarsal proximal perforator; and the communication of the perforator and the dorsal medial vessels. Clinically, six cases of forefoot skin defects were reconstructed with the first metatarsal proximal perforator-based neurocutaneous vascular flap. The medialis dorsalis pedis cutaneous nerve mainly arose from the medial branch of the superficial peroneal nerve and proceeded forward for a distance of 2.5 ± 0.4 cm under the surface of the inferior extensor retinaculum; then, the nerve divided into the medial dorsal branch and the first and second dorsal metatarsal branches. The first metatarsal proximal perforator-based neurocutaneous vessels were multisegmented and multisourced, and the first branch was closely related to the operative procedure. In terms of the clinical application, all flaps of the six cases survived completely with good appearance, texture and elasticity. The first metatarsal proximal perforators present as constant. The first metatarsal proximal perforator-based neurocutaneous vascular flap may become a useful supplemental material for the reconstruction of forefoot defects. Clin. Anat., 2019. © 2019 Wiley Periodicals, Inc.

13.
J Asian Nat Prod Res ; : 1-7, 2019 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-31580152

RESUMO

Seven compounds were isolated from a marine-derived fungus Aspergillus sp. ZF-79, including three new polyketides (1-3), named asperochrins D-F, along with four known compounds 4-7. Their structures were determined on the basis of spectroscopic methods. All the compounds were tested for quorum sensing inhibitory (QSI) activity. Compounds 1, 3, 4, 5, and 6 exhibited QSI activity against Chromobacterium violaceum CV026 with MIC values of 50, 100, 50, 50, and 6.25 µM, respectively.

14.
Psychiatry Res ; 282: 112608, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31655405

RESUMO

OBJECTIVES: Abnormalities in insular functional connectivity have been implicated in many clinical features of schizophrenia. The aim of this study was to determine to what degree such abnormalities occur in individuals with clinical high risk for psychosis (CHR), and whether which is associated with symptom severity. METHODS: Resting-state fMRI data were collected from 47 healthy controls, 24 CHR individuals and 19 patients with first-episode schizophrenia. Using the posterior, dorsal and ventral insular subregions as separate seeds, we examined resting-state functional connectivity differences between different groups and the association between concurrent symptom severity and dysconnectivity. RESULTS: Compared with healthy controls, both CHR individuals and schizophrenia patients showed hypoconnectivity between posterior insula (PI) and somatosensory areas, and between dorsal anterior insula (dAI) and putamen. Schizophrenia patients also showed dAI and ventral anterior insula(vAI) hyperconnectivity with visual areas relative to controls and CHR individuals. Correlation analysis revealed that dAI functional connectivity with superior temporal gyrus was positively correlated with positive symptoms of CHR, and vAI connectivity with dorsolateral prefrontal cortex was negatively correlated with the severity of the symptoms of first-episode schizophrenia. CONCLUSIONS: Our findings suggest that insular functional dysconnectivity with the sensory cortex may be a system-level neural substrate preceding the onset of psychosis.

15.
Dalton Trans ; 48(43): 16199-16210, 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31531480

RESUMO

Alkaline phosphatase (ALP), an extraordinary enzyme, can catalyze the dephosphorylation of small molecules, proteins and nucleic acids. ALP has been confirmed as a crucial serum diagnostic indicator, since the abnormal level of ALP is closely related to a variety of pathological processes, especially in the early diagnosis and screening of cancer. Herein, we designed a "turn-on" sensor to detect ALP and ascorbic acid (AA) based on the redox reaction between manganese dioxide (MnO2) coated upconversion nanoparticles (UCNPs) and AA. Firstly, 2 nm sized NaYF4:Yb3+,Tm3+ UCNPs were synthesized by a facile one-pot hydrothermal method. Then MnO2 coated UCNPs were prepared via electrostatic interactions between MnO2 nanosheets and UCNPs. MnO2 nanosheets could absorb blue light emitted by UCNPs near 471 nm under laser excitation at 980 nm, and so the luminescence of UCNPs was quenched based on luminescence energy transfer (LET). In the presence of AA, the luminescence was recovered again by the redox reaction between AA and MnO2 coated UCNPs. MnO2 nanosheets were reduced to Mn2+ and UCNPs were released. Furthermore, the "turn-on" sensor was applied to monitor ALP since the phosphate group of 2-phospho-l-ascorbic acid (AAP) was removed by ALP to yield AA. The bio-assay showed a good linear relationship between the restored luminescence intensities (ΔI = I-I0) and ALP concentrations ranging from 0.25 to 150 mU mL-1 with a limit of detection (LOD) of 0.045 mU mL-1 and between ΔI and AA concentrations ranging from 0.5 to 250 µM with an LOD of 0.29 µM. The luminescent sensor was also successfully applied for detection of ALP and AA in human serum samples with recoveries from 94.9% to 104.6% and 99.4% to 104.9%.

16.
Cancer Sci ; 110(11): 3510-3519, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31487418

RESUMO

NOP2/Sun domain family, member 2 (NSUN2) is a nuclear RNA methyl-transferase catalyzing 5-methylcytosine formation. Evidence shows that NSUN2 is correlated with cell unlimited proliferation. However, its functional role in gallbladder carcinoma (GBC), which is the most common biliary tract malignancy and has a poor prognosis, remains to be determined. Here we found that NSUN2 was highly expressed in GBC tissues as well as cell lines. NSUN2 silencing repressed GBC cell proliferation and tumorigenesis both in vitro and in vivo. Conversely, upregulation of NSUN2 enhanced GBC cell growth and colony formation. We further discovered that RPL6 was a closely interacting partner with NSUN2. Silencing RPL6 resulted in insufficient NSUN2 translational level and accumulative NSUN2 transcriptional level. Exogenous expression of NSUN2 partially rescued the effect of RPL6 in gallbladder cancer progression. Taken together, our data provided novel mechanic insights into the function of NSUN2 in GBC, thus pointing to NSUN2 as a potential and effective therapeutic approach to GBC treatment.


Assuntos
Carcinoma/metabolismo , Neoplasias da Vesícula Biliar/metabolismo , Metiltransferases/metabolismo , Proteínas de Neoplasias/metabolismo , Proteínas Ribossômicas/metabolismo , Animais , Carcinoma/patologia , Carcinoma/terapia , Linhagem Celular Tumoral , Proliferação de Células , Colecistite/metabolismo , Progressão da Doença , Neoplasias da Vesícula Biliar/patologia , Neoplasias da Vesícula Biliar/terapia , Humanos , Metiltransferases/antagonistas & inibidores , Camundongos , Camundongos Nus , Ensaio Tumoral de Célula-Tronco , Regulação para Cima
17.
Artigo em Inglês | MEDLINE | ID: mdl-31547666

RESUMO

Recently, an increasing number of circulating recombinant forms (CRFs) and unique recombinant forms of HIV-1 have been identified in China, contributing substantially to the genetic variability of this virus. This study reports a novel second-generation recombinant form of HIV-1 (GX2015QZLS204), composed of segments from the CRF07_BC and CRF01_AE strains, which was isolated from an HIV-positive male individual infected through heterosexual contact, while residing in the Guangxi province of southwest China. Analysis of the near full-length genome sequence showed that one segment of the CRF01_AE virus subtype was inserted into the CRF07_BC subtype backbone. Recombination analysis demonstrated that the genome of GX2015QZLS204 was separated into seven segments with six breakpoints. Subregion trees constructed by the neighbor-joining method confirmed that the CRF01_AE segment was from the previously identified CRF01_AE cluster 2, and the CRF07_BC segment correlated with the CRF07_BC strain originating from the Jiangxi and Xinjiang provinces of China. The emergence of GX2015QZLS204 highlights the frequent generation of novel recombinant forms and the increasing complications of the HIV-1 epidemic among heterosexual transmission (HET) groups in China. This highlights the importance of monitoring HIV-1 molecular epidemiological characteristics and the urgent need for reduction of the HIV-1 epidemic among HET groups in China.

18.
ACS Sens ; 4(10): 2654-2661, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31502455

RESUMO

Due to the heterogeneity of cancer cell populations, the traditional evaluation approach of cell viability based on the cell counting assay is quite inaccurate for the dose-response test of anticancer drugs, cell toxicology assays, and other biochemical stimulations. In this paper, an evaluation approach of cell viability based on the cell detachment assay in a single-channel integrated microfluidic chip is proposed to improve the accuracy of cell viability assessment. The electrodes are coated by fibronectin for specific cell adhesion, and it is biologically significant to study the cell detachment assay in vitro. The maximum number of cells that can be detected by this sensor is about 105 cells (overgrowing), while the minimum is about 100 cells. This method is calibrated with the half-maximal inhibitory concentration assay, and the results show that the cell viability calculated by adhesion strength is more accurate than that evaluated using the cell counting assay. Meanwhile, the shear rate is transformed into shear stress for the comparability among the results in other papers. The most sensitive frequency is also determined as 1 kHz according to normalized impedance. Besides, the impedance of cell adhesion affected by different shear stresses is monitored to study the optimized plan for long-term culture of cells in the integrated microfluidic chip prepared for the cell detachment assay. Adhesion strength τ25, which is the magnitude of shear stress needed to detach 75% of cell population, is introduced to describe the cell adhesion forces. It is calculated and normalized based on the cell detachment assay to evaluate cell viability. The relative errors of the cell detachment method compared with those of the cell counting method decrease by 0.637 (0% FBS), 0.586 (0.5% FBS), and 0.342 (2% FBS).

19.
Shanghai Kou Qiang Yi Xue ; 28(3): 231-236, 2019 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-31489407

RESUMO

PURPOSE: To investigate the effect of tooth movement at different time after repair of alveolar bone defects with tissue engineering bone constructed by rabbit bone marrow mesenchymal stem cells (BMSCs) and beta-tricalcium phosphate (ß-TCP). METHODS: Alveolar bone defect (6 mm×4 mm×8 mm) was made on the right side of 40 New Zealand rabbits, which was filled with tissue engineering bone constructed by BMSCs and ß-TCP as experimental sides. Tooth extraction on the other side was performed as control. The mandibular second molars in both sides were moved mesially 2, 4, 8 and 12 weeks after surgery. The specimens were taken 4 weeks after exertion. The distance of mandibular second molar moved was measured. The periodontal tissues were observed after H-E staining. TRAP staining was performed and osteoclasts were counted in the periodontal tissues on the pressure side. BMP-2 immunohistochemical staining was used to observe the average optical density of periodontal tissue on tension side. The results were analyzed with SAS 8.0 software package. RESULTS: The distance of tooth movement, the amount of TRAP positive cells and the optical density of BMP-2 in the experimental side of the 2-week and 4-week groups were all significantly lower than those in the control side, while there was no significant difference between the 8-week and 12-week groups. CONCLUSIONS: Eight weeks after repair of alveolar bone defect with rabbit BMSCs and ß-TCP is an appropriate time for orthodontic tooth movement.


Assuntos
Células-Tronco Mesenquimais , Engenharia Tecidual , Técnicas de Movimentação Dentária , Animais , Fosfatos de Cálcio , Coelhos
20.
J Mech Behav Biomed Mater ; 101: 103423, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31536885

RESUMO

OBJECTIVE: To evaluate the effect of artificial aging on the mechanical resistance and micromechanical properties of commercially and noncommercially available zirconia dental implants. METHODS: Scanning electron microscopy (SEM) and X-ray computed tomography (X-CT) were performed on implant systems including: Z-systems®, Straumann®, Zibone® and commercially and non-commercially available TAV dental® with varying grain sizes. Accelerated aging was performed at 134 °C and 2-bar pressure for 30 hours. Before and after aging, the mechanical load to failure was investigated and the bending moments were calculated. Nanoindentation responses of the representative Zibone implant before and after aging were performed to evaluate the effects of aging on hardness (H) and Young's modulus (E). A two-sample t-test statistical analysis was used to determine significant differences of bending moments within groups. RESULTS: All implants presented with compact and homogenous core structures without porosities. The bending moment was significantly increased after aging for all groups (P ≤ 0.05) except for Z-systems (significant decrease (P = 0.022)) and TAV group 3 (no significant increase (P = 0.181)). The increase in bending moment was less pronounced with increasing grain size in TAV groups (group 1: P = 0.036, group 2: P = 0.05, group 3: P = 0.18). E and H were reduced approximately 32% and 18% respectively following aging within the transformed, microcracked zone of the presentative Zibone implant. CONCLUSIONS: Aging led to both increase and decrease of the mechanical properties of the implant systems analyzed. The apparent contrast amongst groups can be explained based on differences in grain sizes and surface features. Aging decreased micromechanical properties of one implant system which warrants further investigation.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA