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1.
Biomed Pharmacother ; 118: 109031, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31545219

RESUMO

BACKGROUND: This study was conducted to investigate the protective effect of Fms-like tyrosine kinase 3 (FLT3)/FLT3 ligand (FLT3L)-dependent CD103+ dendritic cells (DCs) on hepatic ischemia-reperfusion injury (IRI). METHODS: A mouse model of hepatic IRI and cellular model following hypoxia-reperfusion (H/R) treatment were established. Peripheral blood and liver tissues were obtained and analyzed by flow cytometer in terms of percentage of CD103+DCs and regulatory T (Treg) cells. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were determined to assess liver function. Moreover, pro-inflammatory cytokines levels including tumor necrosis factor (TNF)-α, interleukin (IL)-1ß and IL-6 were measured using enzyme-linked immunosorbent assay (ELISA). The histological morphology of liver tissues was examined with hematoxylin and eosin (HE) staining. The apoptosis was detected by terminal deoxynucleotidyl transferase (TdT) dUTP Nick End Labeling (TUNEL) assay. Treg-associated cytokines transforming growth factor (TGF)-ß and IL-10 expressions were measured using quantitative real time polymerase chain reaction (qRT-PCR). RESULTS: CD103+ DCs were significantly decreased in peripheral blood and liver tissues of mouse model of hepatic IRI. In vivo experiments indicated that CD103+ DCs infusion ameliorated IRI-induced liver damage and Treg inhibition. Further investigations demonstrated that FLT3/FLT3L-dependent CD103+ DCs suppressed hepatocyte apoptosis via activation of Treg cells in vitro. CONCLUSION: FLT3/FLT3L-induced CD103+ DCs alleviated hepatic IRI through activating Treg cells.


Assuntos
Antígenos CD/metabolismo , Células Dendríticas/transplante , Cadeias alfa de Integrinas/metabolismo , Fígado/irrigação sanguínea , Proteínas de Membrana/metabolismo , Traumatismo por Reperfusão/terapia , Linfócitos T Reguladores/imunologia , Tirosina Quinase 3 Semelhante a fms/metabolismo , Animais , Transplante de Células , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Fígado/imunologia , Testes de Função Hepática , Ativação Linfocitária , Camundongos Endogâmicos C57BL , Traumatismo por Reperfusão/imunologia
2.
J Agric Food Chem ; 67(40): 11044-11052, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31545599

RESUMO

Persimmon condensed tannins (PT) are highly polymerized (mDP = 26) and highly galloylated (72%) proanthocyanidins. Its pleiotropic effects in oxidation resistance, neuroprotection, hypolipidemia, and cardio-protection both in vitro and in vivo were widely reported. Because large proanthocyanidins are unlikely to be absorbed in the gastrointestinal tract, it is believed that the interaction of PT with biological membranes may play a crucial role in its biological activities. In the present study, the capacities of PT adsorbing to membrane, partitioning into membrane, and its influence on the membrane fluidity were investigated by fluorescence quenching, isothermal titration calorimetry (ITC) and fluorescence anisotropy measurements in a biomembrane-mimetic system composed of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), 1-palmitoyl-2-oleoylphosphatidylethanolamine (POPE), sphingomyelin (SPM), and cholesterol (CHOL). Besides, the effects of PT on the morphology and integrity of the cell membrane were studied by scanning electron microscopy (SEM) and fluorescence staining in the 3T3-L1 cell model. The results suggested that PT could affect cell membrane rafts domains, destroy the cell membrane morphology, and regulate cell membrane fluidity, which might contribute to its biological effects.


Assuntos
Membrana Celular/química , Diospyros/química , Extratos Vegetais/química , Proantocianidinas/química , Animais , Fenômenos Biofísicos , Membrana Celular/metabolismo , Colesterol/química , Colesterol/metabolismo , Frutas/química , Fluidez de Membrana , Camundongos , Células NIH 3T3 , Fosfatidilcolinas/química , Fosfatidilcolinas/metabolismo , Extratos Vegetais/metabolismo , Polimerização , Proantocianidinas/metabolismo , Esfingomielinas/química , Esfingomielinas/metabolismo
3.
Biochem Biophys Res Commun ; 504(1): 82-88, 2018 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-30177389

RESUMO

Previous study found that AR in prostate may act as both a proliferator and a suppressor to promote or suppress the metastasis of prostate cancer (PCa). In current work, we demonstrated that AR could suppress PCa cell invasion through altering the miR-4496/ß-catenin signals. And mechanisms dissection found that AR could negatively regulate the expression of ß-catenin through enhancing the miR-4496 expression via directly binding to the AR-response-elements (AREs) of miR-4496 promoter, subsequently, the miRNA could directly target the 3' UTR of the ß-catenin-mRNA to reduce its expression. To conclude, our work suggests that AR might play an important role to suppress PCa cell invasion, targeting the newly identified AR/miR-4496/ß-catenin signaling with small molecules may help us to build up new therapeutic approaches to better suppress the metastasis of PCa.


Assuntos
Regulação Neoplásica da Expressão Gênica , MicroRNAs/metabolismo , Neoplasias da Próstata/genética , Receptores Androgênicos/fisiologia , beta Catenina/genética , Linhagem Celular Tumoral , Células HEK293 , Humanos , Masculino , MicroRNAs/genética , Invasividade Neoplásica , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/fisiopatologia , Transdução de Sinais , beta Catenina/metabolismo
4.
Sci Rep ; 6: 19996, 2016 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-26822526

RESUMO

There are two interpretations of the Aharonov-Bohm (A-B) effect. One interpretation asserts that the A-B effect demonstrates that the vector potential is a physical reality that can result in the phase shift of a moving charge in quantum mechanics. The other interpretation asserts that the phase shift of the moving charge results from the interaction energy between the electromagnetic field of the moving charge and external electromagnetic fields. This paper briefly reviews these two interpretations and analyzes their differences. In addition, a new experimental scheme is proposed to determine which interpretation is correct.

5.
Sci Rep ; 5: 14279, 2015 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-26392302

RESUMO

This paper states that the induced charge should not be neglected in the electric Aharonov-Bohm (A-B) effect. If the induced charge is taken into account, the interference pattern of the moving charge will not change with the potential difference between the two metal tubes. It means that the scalar potential itself can not affect the phase of the moving charge, and the true factor affecting the phase of the moving charge is the energy of the system including the moving charge and the induced charge.

6.
Artigo em Chinês | MEDLINE | ID: mdl-25051832

RESUMO

Four adults of Fasciola hepatica were found from the bile ducts of a patient diagnosed as biliary calculi during a surgical operation. We investigated retrospectively the infection source and concluded that the patient may be infected by eating raw or half-cooked Zizania latifolia, an aquatic plant, which was contaminated with metacercariae of F. hepatica.


Assuntos
Fasciola hepatica/fisiologia , Fasciolíase/diagnóstico , Fasciolíase/tratamento farmacológico , Animais , Humanos , Adulto Jovem
7.
Exp Ther Med ; 7(6): 1465-1470, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24926327

RESUMO

The aim of the present study was to investigate the effects of Cordyceps sinensis (CS) and Tripterygium wilfordii polyglycosidium (TWP) on podocytes in rats with diabetic nephropathy (DN). DN rat models were established and divided randomly into normal control (group A), DN (group B), CS (group C), TWP (group D) and CS and TWP groups (group E). After 12 weeks, levels of 24-h urinary protein, blood urea nitrogen (BUN), serum creatinine (SCR), white blood cells, blood glucose (GLU), aspartate aminotransferase, alanine aminotransferase and kidney weight (KW)/body weight (BW) were determined. Renal pathological changes were evaluated using hematoxylin and eosin staining, whereas the structural changes in the podocytes were observed under a transmission electron microscope. The expression levels of nephrin and podocin were evaluated using immunofluorescence staining. Compared with group A, the SCR and BUN levels in group B were higher (P<0.05) and the GLU, KW/BW and the 24-h urine protein were markedly higher (P<0.01). Moreover, incidences of glomerular disorders, chronic tubulointerstitial damage and glomerular podocyte lesions in groups B, C, D and E were observed, compared with group A. The high cortical expression of nephrin and podocin protein decreased. Compared with group B, the KW/BW and 24-h urinary protein level in groups C, D and E were lower (P<0.01). The glomeruli, tubules and podocytes exhibited pathomorphological improvements and the nephrin and podocin protein expression levels were higher in the nephridial tissue. A decrease in KW/BW and the 24-h urinary protein level, as well as improvements in glomerular disorder, chronic tubulointerstitial damage and glomerular podocyte lesions, were observed in groups C, D and E. Therefore, the results demonstrated that CS and TWP exhibited a protective effect on the podocytes of rats with DN. Moreover, CS combined with TWP increased this protective effect.

8.
Mol Biol Rep ; 41(7): 4697-704, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24728565

RESUMO

Pancreatic cancer is a uniformly lethal disease that can be difficult to diagnose at its early stage. Thus, our present study aimed to explore the underlying mechanism and identify new targets for this disease. The data GSE16515, including 36 tumor and 16 normal samples were available from Gene Expression Omnibus. Differentially expressed genes (DEGs) were screened out using Robust Multichip Averaging and LIMMA package. Moreover, gene ontology and pathway enrichment analyses were performed to DEGs. Followed with protein-protein interaction (PPI) network construction by STRING and Cytoscape, module analysis was conducted using ClusterONE. Finally, based on PubMed, text mining about these DEGs was carried out. Total 274 up-regulated and 93 down-regulated genes were identified as the common DEGs and these genes were discovered significantly enriched in cell adhesion and extracellular region terms, as well as ECM-receptor interaction pathway. In addition, five modules were screened out from the up-regulated PPI network with none in down-regulated network. Finally, the up-regulated genes, including MIA, MET and CEACAMS, and down-regulated genes, such as FGF, INS and LAPP, had the most references in text mining analysis. Our findings demonstrate that the up- and down-regulated genes play important roles in pancreatic cancer development and might be new targets for the therapy.


Assuntos
Regulação Neoplásica da Expressão Gênica , Redes Reguladoras de Genes , Proteínas de Neoplasias/genética , Neoplasias Pancreáticas/genética , Biologia Computacional , Mineração de Dados , Bases de Dados Genéticas , Perfilação da Expressão Gênica , Humanos , Redes e Vias Metabólicas/genética , Proteínas de Neoplasias/metabolismo , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Mapeamento de Interação de Proteínas , Transdução de Sinais
9.
Imaging Sci Dent ; 44(1): 15-20, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24701454

RESUMO

PURPOSE: This study aimed to assess the three-dimensional (3D) facial changes after orthognathic surgery by evaluating the spherical coordinates of facial lines using 3D computed tomography (CT). MATERIALS AND METHODS: A 19-year-old girl was diagnosed with class III malocclusion and facial asymmetry. Orthognathic surgery was performed after orthodontic treatment. Facial CT scans were taken before and after orthognathic surgery. The patient had a menton deviation of 12.72 mm before surgery and 0.83 mm after surgery. The spherical coordinates of four bilateral facial lines (ramal height, ramal lateral, ramal posterior and mandibular body) were estimated from CT scans before and after surgery on the deviated and opposite side. RESULTS: The spherical coordinates of all facial lines changed after orthognathic surgery. Moreover, the bilateral differences of all facial lines changed after surgery, and no bilateral differences were zero. CONCLUSION: The spherical coordinate system was useful to compare differences between the presurgical and postsurgical changes to facial lines.

10.
Imaging Sci Dent ; 43(1): 31-6, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23525239

RESUMO

PURPOSE: This study aimed to measure the bilateral differences of facial lines in spherical coordinates from faces within a normal range of asymmetry utilizing cone-beam computed tomography (CBCT). MATERIALS AND METHODS: CBCT scans from 22 females with normal symmetric-looking faces (mean age 24 years and 8 months) were selected for the study. The average menton deviation was 1.01±0.66 mm. The spherical coordinates, length, and midsagittal and coronal inclination angles of the ramal and mandibular lines were calculated from CBCT. The bilateral differences in the facial lines were determined. RESULTS: All of the study subjects had minimal bilateral differences of facial lines. The normal range of facial asymmetry of the ramal and mandibular lines was obtained in spherical coordinates. CONCLUSION: The normal range of facial asymmetry in the spherical coordinate system in this study should be useful as a reference for diagnosing facial asymmetry.

11.
Dig Dis Sci ; 58(9): 2550-5, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22945476

RESUMO

BACKGROUND: Functional dyspepsia-epigastric pain syndrome (FD-EPS) is characterized pathophysiologically by visceral hypersensitivity, but the effect of the temperature stimulation on gastric function has been seldom studied. AIM: The purpose of this study was to investigate the effects of liquid nutrients at different temperatures on the gastric accommodation, sensitivity, and gastric-wall compliance of healthy subjects (HS) and FD-EPS patients. METHODS: Ten FD-EPS patients (Roma III criteria) and ten HS were recruited into the study. Intragastric pressure (IGP) and gastric perfusion were measured and compared following the administration of liquid nutrients at 37 °C on day 1 and at 8 °C on day 2. RESULTS: Seven patients developed abdominal discomfort or abdominal pain after being given cold liquid nutrient. The administration of liquid nutrient at 8 °C resulted in an increase of IGP in HS (P=0.044), a significant decrease in gastric perfusion (P<0.0001), a marked increase in IGP (P=0.015), and a dramatic reduction in gastric wall compliance (P=0.012) in patients compared to the effects of liquid nutrient at 37 °C. In addition, IGP in patients was lower than that in HS at 37 °C liquid nutrient (P=0.036), and the gastric perfusion volume in patients at maximal satiety was also significantly reduced at 8 °C liquid nutrient compared with HS (P=0.017). CONCLUSIONS: Cold stimulation can increase the IGP in HS and FD-EPS patients, elevate the visceral sensitivity and reduce the gastric volume of FD-EPS patients. FD-EPS patients who are sensitive to cold may develop epigastric discomfort or pain.


Assuntos
Temperatura Baixa , Dispepsia/fisiopatologia , Estômago/fisiopatologia , Adulto , Estudos de Casos e Controles , Complacência (Medida de Distensibilidade) , Ingestão de Líquidos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pressão
12.
J Plast Reconstr Aesthet Surg ; 66(2): 193-200, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23102763

RESUMO

BACKGROUND: Thoracodorsal artery perforator (TAP) flaps without latissimus dorsi muscle - have been used for reconstruction of the extremities, head and neck as free style flaps, and as pedicled flaps for reconstruction of the chest wall and axillary wounds. This retrospective study aimed to analyse the clinical applications and relevant anatomic findings of TAP flaps. METHODS: From April 2007 to August 2011, 67 free or pedicled TAP flaps were transferred in 67 patients for reconstruction of wounds of the extremities, chest wall and axilla. Eight were used as free flaps for reconstruction of extremities, and 59 used as pedicled flaps for reconstruction of axillary or chest wounds. Patient ages ranged from 7 to 55 years (26.04±12.83). Perforator arteries were detected and identified with a hand-held Doppler. The size of flaps ranged from 6 by 9 to 14 by 18 cm ((8.66±2.05) by (12.62±2.03)). Flaps were designed with the perforator artery included, with all flaps based on one or two perforator arteries. RESULTS: All of the flaps survived. There were no problems with vascular spasm or occlusion. Significant venous congestion was not observed in any of the cases. Two cases developed minor wound dehiscence but healed with conservative therapy. None of the donor sites developed seromas. CONCLUSIONS: The thoracodorsal artery flap without associated latissimus dorsi muscle can provide a thin, large and reliable flap with robust blood supply. The TAP flap can significantly reduce donor site morbidity.


Assuntos
Retalho Perfurante/irrigação sanguínea , Procedimentos Cirúrgicos Reconstrutivos/métodos , Artérias Torácicas/transplante , Cicatrização/fisiologia , Adolescente , Adulto , Axila/cirurgia , Criança , Estudos de Coortes , Extremidades/fisiopatologia , Extremidades/cirurgia , Feminino , Sobrevivência de Enxerto , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Fluxo Sanguíneo Regional/fisiologia , Estudos Retrospectivos , Medição de Risco , Retalhos Cirúrgicos/irrigação sanguínea , Artérias Torácicas/cirurgia , Parede Torácica/cirurgia , Resultado do Tratamento , Ferimentos e Lesões/cirurgia , Adulto Jovem
13.
Int J Dent ; 2012: 374315, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22550486

RESUMO

Statement of the Problem. Fit of prosthodontic frameworks is linked to the lifetime survival of dental implants and maintenance of surrounding bone. Purpose. The purpose of this study was to evaluate and compare the precision of fit of milled one-piece Titanium fixed complete denture frameworks to that of conventional cast frameworks. Material and Methods. Fifteen casts fabricated from a single edentulous CAD/CAM surgical guide were separated in two groups and resin patterns simulating the framework for a fixed complete denture developed. Five casts were sent to dental laboratories to invest, cast in a Palladium-Gold alloy and fit the framework. Ten casts had the resin pattern scanned for fabrication of milled bars in Titanium. Using measuring software, positions of implant replicas in the definitive model were recorded. The three dimensional spatial orientation of each implant replica was matched to the implant replica. Results. Results demonstrated the mean vertical gap of the Cast framework was 0.021 (+0.004) mm and 0.012 (0.002) mm determined by fixed and unfixed best-fit matching coordinate system. For Titanium frameworks they were 0.0037 (+0.0028) mm and 0.0024 (+0.0005) mm, respectively. Conclusions. Milled one-piece Titanium fixed complete denture frameworks provided a more accurate precision of fit then traditional cast frameworks.

14.
Imaging Sci Dent ; 41(3): 95-100, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22010065

RESUMO

PURPOSE: The purpose of this study was to compare asymmetric mandibular prognathism individuals with symmetric mandibular prognathism individuals using a new alternate spherical coordinate system. MATERIALS AND METHODS: This study consisted of 47 computed tomographic images of patients with mandibular prognathism. The patients were classified into symmetric and asymmetric groups. Mandibular and ramal lines were analyzed using an alternate spherical coordinate system. The length as well as midsagittal and coronal inclination angle of the lines was obtained. The bilateral differences of the spherical coordinates of the facial lines were statistically analyzed in the groups. RESULTS: There were significant differences between the groups in bilateral difference of the length and midsagittal inclination angle of the lines (p<0.05). The bilateral difference of the length and midsagittal inclination angle of the lines has significant correlation with chin deviation (p<0.05). CONCLUSION: The new alternate spherical coordinate system was able to effectively evaluate facial lines. The bilateral difference of lengths and midsagittal inclination of the facial lines might contribute to the facial asymmetry in mandibular prognathism individuals.

15.
J Prosthet Dent ; 101(6): 359-71, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19463663

RESUMO

STATEMENT OF PROBLEM: A fundamental problem in fully understanding the dynamic nature of implant loading is the confusion that exists regarding the torque load delivered to the implant complex, the initial force transformation/stress/strain developed within the system during the implant complex assembly, and how the clamping forces at the interfaces and the preload stress impact the implant prior to any external loading. PURPOSE: The purpose of this study was to create an accurately dimensioned finite element model with spiral threads and threaded bores included in the implant complex, positioned in a bone model, and to determine the magnitude and distribution of the force transformation/stress/strain patterns developed in the modeled implant system and bone and, thus, provide the foundational data for the study of the dynamic loading of dental implants prior to any external loading. MATERIAL AND METHODS: An implant (Brånemark Mark III), abutment (CeraOne), abutment screw (Unigrip), and the bone surrounding the implant were modeled using HyperMesh software. The threaded interfaces between screw/implant and implant/bone were designed as a spiral thread helix assigned with specific coefficient of friction values. Assembly simulation using ABAQUS and LS-DYNA was accomplished by applying a 32-Ncm horizontal torque load on the abutment screw (Step 1), then decreasing the torque load to 0 Ncm to simulate the wrench removal (Step 2). The postscript data were collected and reviewed by HyperMesh. A regression analysis was used to depict the relationships between the torque load and the mechanical parameters. RESULTS: During the 32-Ncm tightening sequence, the abutment screw elongated 13.3 mum. The tightening torque generated a 554-N clamping force at the abutment/implant interface and a 522-N preload. The von Mises stress values were 248 MPa in the abutment at the abutment-implant interface, 765 MPa at the top of the screw shaft, 694 MPa at the bottom of the screw shaft, 1365 MPa in the top screw thread, and 21 MPa in the bone at the top of the implant-bone interface. This study also identified various characteristic isosurface stress patterns. The maximum stress magnitude to complete the von Mises stress joint pattern in the present model was 107 MPa during screw tightening, and was reduced to 104 MPa with removal of the wrench. Various specific stress patterns were identified within all elements of the implant complex during the assembly simulation. CONCLUSIONS: During the torque moment application, the abutment screw was elongated, and every 1.0-mum elongation of the screw was equivalent to a 47.9-N increase of the preload in the implant complex. The ideal index to determine the preload amount was the contact force at the interface between the screw threads and the threaded screw bore. The isosurface mode identified various characteristic stress patterns developed within the implant complex at the various interfaces during the assembly simulation. These patterns are the (1) spiral and ying-yang pattern of the XY stress, (2) spring, cap, clamping, and preload pattern of the ZZ stress, and (3) bone holding and joint pattern of the von Mises stress.


Assuntos
Simulação por Computador , Implantes Dentários , Prótese Dentária Fixada por Implante , Análise do Estresse Dentário , Fenômenos Biomecânicos , Força de Mordida , Dente Suporte , Modelos Dentários , Planejamento de Prótese Dentária , Análise do Estresse Dentário/métodos , Análise de Elementos Finitos , Humanos , Modelos Lineares , Torque , Suporte de Carga
16.
Scand J Gastroenterol ; 43(12): 1522-8, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18781453

RESUMO

OBJECTIVE: To investigate alterations of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, the Notch/Jagged signaling pathway, and hepatocyte proliferation, and their correlation in rats subjected to partial hepatectomy. MATERIAL AND METHODS: Blood and liver tissues were sampled immediately (0), 5, 15, 30, 60, 180, 360, and 720 min, and 1, 2, 4, and 7 days after partial (70%) hepatectomy to measure plasma levels of TNF-alpha and IL-6, the expression of proliferating cell nuclear antigen (PCNA), Notch-1 and Jagged-1 protein, and mRNA in liver tissue. RESULTS: Systemic levels of IL-6 significantly correlated with the expression of PCNA in hepatocytes (p<0.05) after partial (70%) hepatectomy. The increased expression of Notch-1 protein was located in the sinusoidal endothelium, while Jagged-1 protein was predominantly located in bile duct cells. Expression of both proteins was increased around the portal vein. mRNA expression of Notch-1 decreased between 6 h and 2 days after partial hepatectomy, while Jagged-1 increased between 3 and 6 h, decreased between 12 h and 2 days, and normalized on day 4 after hepatectomy. CONCLUSIONS: Partial hepatectomy-induced hepatocyte proliferation was accompanied by an increase in systemic levels of IL-6, a pro-inflammatory response that plays a part in the proliferative process. The Notch/Jagged signaling pathways are activated and probably represent important contributors to the regenerative process following hepatectomy including both hepatocyte proliferation and bile duct formation and growth.


Assuntos
Proteínas de Ligação ao Cálcio/biossíntese , Hepatectomia , Hepatócitos/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/biossíntese , Proteínas de Membrana/biossíntese , Antígeno Nuclear de Célula em Proliferação/biossíntese , Receptor Notch1/biossíntese , Animais , Proliferação de Células , Feminino , Expressão Gênica , Interleucina-6/sangue , Proteína Jagged-1 , Ratos , Ratos Wistar , Proteínas Serrate-Jagged , Fator de Necrose Tumoral alfa/sangue , Regulação para Cima
17.
J Prosthet Dent ; 90(6): 539-46, 2003 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-14668754

RESUMO

STATEMENT OF PROBLEM: The nature of the forces used to clamp implant components together, and how they are generated and sustained, is lacking in the literature. PURPOSE: This study examined the dynamic nature of developing the preload in an implant complex using finite element analysis. METHODS: The implant complex was modeled in accordance with the geometric designs for the Nobel Biocare implant systems. A thread helix design for the abutment screw and implant screw bore was modeled to create the geometric design for these units of the implant systems. Using the software programs HyperWorks and LS3D-Dyna, 2 3-dimensional finite element models of (1) a Branemark System 3.75 x 10-mm titanium Mark III implant, a CeraOne titanium abutment, a Unigrip gold alloy abutment screw, and (2) a Replace Select System 4.30 x 10-mm titanium implant, a Straight Esthetic titanium abutment, and a TorqTite titanium abutment screw were created. Modeling the threads to the machining specifications permitted simulation of screw tightening. The abutment screws were subjected to a tightening torque in increments of 1 Ncm from 0 to 64 Ncm using ABAQUS software. Using these models, the effect of the coefficient of friction on the development of preload amount in the implant complex during and after abutment screw tightening was determined. In the first experiment, the coefficient of friction was set to 0.20 between the titanium bearing surface of the abutments and the implant bearing surfaces, and 0.26 between the gold abutment screw and the titanium implant screw bore. In the second experiment, the coefficient of friction was varied; the titanium implant and titanium abutment bearing surfaces were set to a coefficient of friction of 0.20, whereas the Mark III gold and the Replace Select titanium abutment screws and their respective titanium screw bores in the implants were set to 0.12. The preload amount (N) was determined from the finite element analysis. RESULTS: The stress distribution pattern clearly demonstrated a transfer of preload force from the screw to the implant during tightening. A preload of 75% of the yield strength of the abutment screw was not established using the recommended tightening torques. CONCLUSION: Using finite element analysis, a torque of 32 Ncm applied to the abutment screws in the implant assemblies studied in the presence of a coefficient of friction of 0.26 resulted in a lower than optimum preload for the abutment screws. To reach the desired preload of 75% of the yield strength, using a torque of 32 Ncm applied to the abutment screws in the implant assemblies studied, the coefficient of friction between the implant components should be 0.12.


Assuntos
Dente Suporte , Implantação Dentária Endo-Óssea/métodos , Implantes Dentários , Análise do Estresse Dentário/métodos , Modelos Dentários , Planejamento de Prótese Dentária , Retenção em Prótese Dentária/instrumentação , Elasticidade , Análise de Elementos Finitos , Fricção , Humanos , Modelos Biológicos , Titânio , Torque
18.
Int J Oral Maxillofac Implants ; 18(5): 652-8, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-14579952

RESUMO

PURPOSE: It has been suggested that the CAD/CAM Procera custom abutment may be universally applied with multiple implant systems. An acceptable fit between the internal hexagon of an abutment and the external hexagon of various implant systems, along with true interchangeability of the Procera abutment screw, would support this concept. This study determined the precision of fit of the CAD/CAM-produced Procera abutment onto the external hexagon and bearing surfaces of implants from 6 implant manufacturers and the interchangeability of the Procera abutment screw with these systems. MATERIALS AND METHODS: This investigation consisted of 3 parts: (1) direct measurement of the internal hexagon and bearing surface of each Procera abutment and the external hexagon and the bearing surface of 6 implants from 6 different systems, (2) radiographic examination of 30 Procera abutment-implant junctions following tightening to 32 Ncm to determine the precision of fit between the bearing surfaces and the top of the external hexagon of the implant with the superior surface of the internal hexagon of the abutment, and (3) examination of 3 abutment screws and 3 implants from the various manufacturers for interchangeability based on American National Standards. RESULTS: The mean flat-to-flat external hexagons of the implants measured between 2.67 and 2.69 mm. The Procera abutment's flat-to-flat internal hexagon measured 2.73 mm. The height of the various implant systems' external hexagon ranged from 0.69 to 0.81 mm. The height of the Procera abutment blanks was 0.90 mm. Radiographic examination demonstrated that not all of the manufacturers' screws fit appropriately within the internal screw bore of the Procera abutment. The internal bore of all implant systems studied had a metric thread designation of M2 x 0.4 - 6H. The metric thread designation of all abutment screws examined was M2 x 0.4 - 6g. The greatest variations in the dimensions of the abutment screws measured were seen in the diameter of the screw head, which ranged from 2.12 to 2.69 mm. DISCUSSION: The Procera abutment's internal hexagon fit the external hexagon of all implant systems evaluated. The Procera abutment screw fit the internal screw bore of the implant systems tested. CONCLUSION: The Procera abutment with its screw can be universally applied to the implant systems studied. This fact, plus the CAD/CAM feature of this system, would thus provide a dynamic approach to satisfying the design and spatial needs of implant placements observed clinically.


Assuntos
Dente Suporte , Implantes Dentários , Porcelana Dentária , Planejamento de Prótese Dentária , Ligas Metalo-Cerâmicas , Titânio , Desenho Assistido por Computador , Coroas , Implantação Dentária Endo-Óssea/instrumentação , Porcelana Dentária/química , Humanos , Teste de Materiais , Ligas Metalo-Cerâmicas/química , Radiografia Dentária , Propriedades de Superfície , Titânio/química
19.
J Prosthet Dent ; 87(1): 74-9, 2002 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11807487

RESUMO

STATEMENT OF PROBLEM: Limiting abutment-to-implant hexagonal discrepancies and rotational movement of the abutment around the implant to less than 5 degrees would result in a more stable screw joint. However, the exact relationship after abutment screw tightening is unknown, as is the effect of a counter-torque device in limiting abutment movement during screw tightening. PURPOSE: This study examined the orientation of the abutment hexagon to the implant hexagon after tightening of the abutment screw for several abutment systems with and without the use of a counter-torque device. MATERIAL AND METHODS: Thirty conical self-tapping implants (3.75 x 10.0 mm) and 10 wide-platform Brånemark System implants (5.0 x 10.0 mm), along with 10 abutment specimens from the CeraOne, Estheticone, Procera, and AuraAdapt systems, were selected for this investigation. The implants were placed in a holding device prior to tightening of the abutments. When the tightening torque recommended for each abutment system was reached with the use of a torque controller, each implant abutment specimen was removed from the holding device and embedded in a hard resin medium. The specimens were sectioned in a horizontal direction at the level of the hexagons and cleansed of debris prior to examination. The hexagon orientations were assessed as the degree and direction of rotation of the abutment hexagon around the implant hexagon. RESULTS: The range of the maximum degrees of rotation for all 4 abutment groups tightened with or without the counter-torque device was slightly more than 3.53 degrees. The absolute degrees of rotation for all 4 abutment groups were less than 1.50 degrees with or without the use of the counter-torque device. CONCLUSION: The hexagon-to-hexagon orientation measured as rotational fit on all abutment systems was below the 5 degrees suggested as optimal for screw joint stability. The absolute degrees of rotation for all 4 abutment groups were less than 1.50 degrees regardless of whether the counter-torque device was used.


Assuntos
Dente Suporte , Implantes Dentários , Planejamento de Prótese Dentária , Humanos , Rotação , Estresse Mecânico , Propriedades de Superfície , Torque
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