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1.
Science ; 357(6354): 928-932, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28860386

RESUMO

NAD+ (oxidized form of NAD:nicotinamide adenine dinucleotide)-reducing soluble [NiFe]-hydrogenase (SH) is phylogenetically related to NADH (reduced form of NAD+):quinone oxidoreductase (complex I), but the geometrical arrangements of the subunits and Fe-S clusters are unclear. Here, we describe the crystal structures of SH in the oxidized and reduced states. The cluster arrangement is similar to that of complex I, but the subunits orientation is not, which supports the hypothesis that subunits evolved as prebuilt modules. The oxidized active site includes a six-coordinate Ni, which is unprecedented for hydrogenases, whose coordination geometry would prevent O2 from approaching. In the reduced state showing the normal active site structure without a physiological electron acceptor, the flavin mononucleotide cofactor is dissociated, which may be caused by the oxidation state change of nearby Fe-S clusters and may suppress production of reactive oxygen species.


Assuntos
Proteínas de Bactérias/química , Hidrogenase/química , NAD/química , Sítios de Ligação , Oxirredução , Conformação Proteica , Subunidades Proteicas/química , Solubilidade
2.
J Gastroenterol ; 53(3): 276-300, mar. 2017.
Artigo em Inglês | BIGG | ID: biblio-963634

RESUMO

BACKGROUND: This clinical practice guideline addresses six questions related to liberation from mechanical ventilation in critically ill adults. It is the result of a collaborative effort between the American Thoracic Society (ATS) and the American College of Chest Physicians (CHEST). METHODS: A multidisciplinary panel posed six clinical questions in a population, intervention, comparator, outcomes (PICO) format. A comprehensive literature search and evidence synthesis was performed for each question, which included appraising the quality of evidence using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. The Evidence-to-Decision framework was applied to each question, requiring the panel to evaluate and weigh the importance of the problem, confidence in the evidence, certainty about how much the public values the main outcomes, magnitude and balance of desirable and undesirable outcomes, resources and costs associated with the intervention, impact on health disparities, and acceptability and feasibility of the intervention. RESULTS: Evidence-based recommendations were formulated and graded initially by subcommittees and then modified following full panel discussions. The recommendations were confirmed by confidential electronic voting; approval required that at least 80% of the panel members agree with the recommendation. CONCLUSIONS: The panel provides recommendations regarding liberation from mechanical ventilation. The details regarding the evidence and rationale for each recommendation are presented in the American Journal of Respiratory and Critical Care Medicine and CHEST


Assuntos
Humanos , Colelitíase/diagnóstico , Colelitíase/terapia , Ácido Ursodesoxicólico , Litotripsia , Esfinterotomia Endoscópica , Colecistectomia Laparoscópica , Coledocolitíase/terapia , Abordagem GRADE
3.
J Environ Radioact ; 166(Pt 1): 97-103, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26830016

RESUMO

Plutonium (238Pu and 239,240Pu), 137Cs and plutonium activity ratios (238Pu/239,240Pu) as did uranium isotope ratio (235U/238U) were measured in surface soil samples collected in southeast Mongolia. The 239,240Pu and 137Cs concentrations in Mongolian surface soils (<53 µm of particle size) ranged from 0.42 ± 0.03 to 3.53 ± 0.09 mBq g-1 and from 11.6 ± 0.7 to 102 ± 1 mBq g-1, respectively. The 238Pu/239,240Pu activity ratios in the surface soils (0.013-0.06) coincided with that of global fallout. The 235U/238U atom ratios in the surface soil show the natural one. There was a good correlation between the 239,240Pu and 137Cs concentrations in the surface soils. We introduce the migration depth to have better understanding of migration behaviors of anthropogenic radionuclides in surface soil. We found a difference of the migration behavior between 239,240Pu and 137Cs from 137Cs/239,240Pu - 137Cs plots for the Mongolian and Tsukuba surface soils; plutonium in surface soil is migrated easier than 137Cs.


Assuntos
Radioisótopos de Césio/análise , Plutônio/análise , Monitoramento de Radiação , Poluentes Radioativos do Solo/análise , Urânio/análise , Mongólia
4.
Diabet Med ; 34(4): 586-589, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-27859559

RESUMO

AIM: To examine the contribution of the FUT2 gene and ABO blood type to the development of Type 1 diabetes in Japanese children. METHODS: We analysed FUT2 variants and ABO genotypes in a total of 531 Japanese children diagnosed with Type 1 diabetes and 448 control subjects. The possible association of FUT2 variants and ABO genotypes with the onset of Type 1 diabetes was statistically examined. RESULTS: The se2 genotype (c.385A>T) of the FUT2 gene was found to confer susceptibility to Type 1A diabetes in a recessive effects model [odds ratio for se2/se2, 1.68 (95% CI 1.20-2.35); corrected P value = 0.0075]. CONCLUSIONS: The FUT2 gene contributed to the development of Type 1 diabetes in the present cohort of Japanese children.


Assuntos
Diabetes Mellitus Tipo 1/genética , Fucosiltransferases/genética , Sistema ABO de Grupos Sanguíneos/genética , Povo Asiático/genética , Estudos de Casos e Controles , Predisposição Genética para Doença , Humanos , Japão , Galactosídeo 2-alfa-L-Fucosiltransferase
5.
Phys Rev Lett ; 117(20): 202501, 2016 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-27886506

RESUMO

Excitation spectra of ^{11}C are measured in the ^{12}C(p,d) reaction near the η^{'} emission threshold. A proton beam extracted from the synchrotron SIS-18 at GSI with an incident energy of 2.5 GeV impinges on a carbon target. The momenta of deuterons emitted at 0° are precisely measured with the fragment separator (FRS) operated as a spectrometer. In contrast to theoretical predictions on the possible existence of deeply bound η^{'}-mesic states in carbon nuclei, no distinct structures are observed associated with the formation of bound states. The spectra are analyzed to set stringent constraints on the formation cross section and on the hitherto barely known η^{'}-nucleus interaction.

7.
Diabet Med ; 33(12): 1717-1722, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27352912

RESUMO

AIMS: The aim of this study was to clarify the significance of previously reported susceptibility variants in the development of autoimmune Type 1 diabetes in non-white children. Tested variants included rs2290400, which has been linked to Type 1 diabetes only in one study on white people. Haplotypes at 17q12-q21 encompassing rs2290400 are known to determine the susceptibility of early-onset asthma by affecting the expression of flanking genes. METHODS: We genotyped 63 variants in 428 Japanese people with childhood-onset autoimmune Type 1 diabetes and 457 individuals without diabetes. Possible association between variants and age at diabetes onset was examined using age-specific quantitative trait locus analysis and ordered-subset regression analysis. RESULTS: Ten variants, including rs2290400 in GSDMB, were more frequent among the people with Type 1 diabetes than those without diabetes. Of these, rs689 in INS and rs231775 in CTLA4 yielded particularly high odds ratios of 5.58 (corrected P value 0.001; 95% CI 2.15-14.47) and 1.64 (corrected P value 5.3 × 10-5 ; 95% CI 1.34-2.01), respectively. Age-specific effects on diabetes susceptibility were suggested for rs2290400; heterozygosity of the risk alleles was associated with relatively early onset of diabetes, and the allele was linked to the phenotype exclusively in the subgroup of age at onset ≤ 5.0 years. CONCLUSIONS: The results indicate that rs2290400 in GSDMB and polymorphisms in INS and CTLA4 are associated with the risk of Type 1 diabetes in Japanese children. Importantly, cis-regulatory haplotypes at 17q12-q21 encompassing rs2290400 probably determine the risk of autoimmune Type 1 diabetes predominantly in early childhood.


Assuntos
Cromossomos Humanos Par 17/genética , Diabetes Mellitus Tipo 1/genética , Haplótipos/genética , Polimorfismo de Nucleotídeo Único/genética , Adolescente , Adulto , Idade de Início , Idoso , Alelos , Criança , Pré-Escolar , Feminino , Frequência do Gene/genética , Predisposição Genética para Doença/genética , Humanos , Lactente , Japão/etnologia , Masculino , Pessoa de Meia-Idade , Adulto Jovem
8.
J Oral Rehabil ; 43(7): 534-42, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-26854877

RESUMO

The aim of this multicentre study was to investigate the effect of prosthetic restoration for missing posterior teeth on mastication in patients with shortened dental arches (SDAs). Partially dentate patients who had an intact teeth in anterior region and missed distal molar(s) (2-12 missing occlusal units) classified as Kennedy Class I or Class II were recruited from seven university-based dental hospitals in Japan. Of the 125 subjects who underwent baseline (pre-treatment) and follow-up/post-treatment evaluation, 53 chose no replacement of missing teeth and 72 chose treatment with removable partial dentures (n = 53) or implant-supported fixed partial dentures (n = 19). Objective masticatory performance (MP) was evaluated using a gummy jelly test. Perception of chewing ability (CA) was rated using a food intake questionnaire. In the no-treatment group, mean MP and CA scores at baseline were similar to those at follow-up evaluation (P > 0·05). In the treatment group, mean MP after treatment was significantly greater than the pre-treatment mean MP (P < 0·05). However, the mean perceived CA in the treatment groups was similar at pre- and post-treatment (P > 0·05). In a subgroup analysis of subjects in the treatment group, subjects with lower pre-treatment CA showed a significant CA increase after treatment (P = 0·004), but those with higher pre-treatment CA showed a significant decrease in CA (P = 0·001). These results suggest that prosthetic restoration for SDAs may benefit objective masticatory performance in patients needing replacement of missing posterior teeth, but the benefit in subjective chewing ability seems to be limited in subjects with perceived impairment in chewing ability before treatment.


Assuntos
Arco Dental/fisiopatologia , Prótese Parcial Fixa , Prótese Parcial Removível , Arcada Parcialmente Edêntula/fisiopatologia , Mastigação/fisiologia , Feminino , Humanos , Japão/epidemiologia , Arcada Parcialmente Edêntula/psicologia , Arcada Parcialmente Edêntula/terapia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Qualidade de Vida
9.
Phys Rev Lett ; 115(7): 071801, 2015 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-26317713

RESUMO

A new measurement of the branching ratio R_{e/µ}=Γ(π^{+}→e^{+}ν+π^{+}→e^{+}νγ)/Γ(π^{+}→µ^{+}ν+π^{+}→µ^{+}νγ) resulted in R_{e/µ}^{exp}=[1.2344±0.0023(stat)±0.0019(syst)]×10^{-4}. This is in agreement with the standard model prediction and improves the test of electron-muon universality to the level of 0.1%.

10.
J Oral Rehabil ; 42(9): 701-8, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25818656

RESUMO

The aim of this multicentre prospective study was to investigate the effect of prosthetic restoration for missing posterior teeth in patients with shortened dental arches (SDAs). SDA patients with 2-12 missing occlusal units (a pair of occluding premolars corresponds to one unit, and a pair of occluding molars corresponds to two units) were consecutively recruited from seven university-based dental hospitals in Japan. Patients chose no replacement of missing teeth or prosthetic treatment with removable partial dentures (RPDs) or implant-supported fixed partial dentures (IFPDs). Oral health-related quality of life (OHRQoL) was measured using the oral health impact profile (Japanese version - OHIP-J) at baseline and follow-up/post-treatment evaluation. Of the 169 subjects who completed baseline evaluation, 125 subjects (mean age; 63.0 years) received follow-up/post-treatment evaluation. No-treatment was chosen by 42% (53/125) of the subjects, and 58% (72/125) chose treatment with a RPD (n = 53) or an IFPD (n = 19). In the no-treatment (NT) group, the mean OHIP summary score at baseline was similar to that at follow-up evaluation (P = 0.69). In the treatment (TRT) group, the mean OHIP summary score decreased significantly after the RPD treatment (P = 0.002), and it tended to decrease, though not statistically significant (P = 0.18), after the IFPD treatment. The restoration of one occlusal unit was associated with a 1.2-point decrease in OHIP summary score (P = 0.034). These results suggest that the replacement of missing posterior teeth with RPDs or IFPDs improved OHRQoL. Prosthetic restoration for SDAs may benefit OHRQoL in patients needing replacement of missing posterior teeth.


Assuntos
Arco Dental/patologia , Prótese Parcial Removível/psicologia , Arcada Parcialmente Edêntula/psicologia , Arcada Parcialmente Edêntula/terapia , Saúde Bucal , Qualidade de Vida , Feminino , Humanos , Japão/epidemiologia , Arcada Parcialmente Edêntula/patologia , Masculino , Pessoa de Meia-Idade , Saúde Bucal/estatística & dados numéricos , Estudos Prospectivos , Perfil de Impacto da Doença , Resultado do Tratamento
11.
Nutr Diabetes ; 4: e141, 2014 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-25329603

RESUMO

OBJECTIVE: Recent studies indicate that sphingolipids, sphingomyelin (SM) and ceramide (Cer) are associated with the development of metabolic syndrome. However, detailed profiles of serum sphingolipids in the pathogenesis of this syndrome are lacking. Here we have investigated the relationship between the molecular species of sphingolipids in serum and the clinical features of metabolic syndrome, such as obesity, insulin resistance, fatty liver disease and atherogenic dyslipidemia. SUBJECTS: We collected serum from obese (body mass index, BMI⩾35, n=12) and control (BMI=20-22, n=11) volunteers (18-27 years old), measured the levels of molecular species of SM and Cer in the serum by liquid chromatography-mass spectrometry and analyzed the parameters for insulin resistance, liver function and lipid metabolism by biochemical blood test. RESULTS: The SM C18:0 and C24:0 levels were higher, and the C20:0 and C22:0 levels tended to be higher in the obese group than in the control group. SM C18:0, C20:0, C22:0 and C24:0 significantly correlated with the parameters for obesity, insulin resistance, liver function and lipid metabolism, respectively. In addition, some Cer species tended to correlate with these parameters. However, SM species containing unsaturated acyl chains and most of the Cer species were not associated with these parameters. CONCLUSIONS: The present results demonstrate that the high levels of serum SM species with distinct saturated acyl chains (C18:0, C20:0, C22:0 and C24:0) closely correlate with the parameters of obesity, insulin resistance, liver function and lipid metabolism, suggesting that these SM species are associated with the development of metabolic syndrome and serve as novel biomarkers of metabolic syndrome and its associated diseases.

12.
Transplant Proc ; 46(6): 1942-4, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25131077

RESUMO

OBJECTIVE: We previously demonstrated that collagenase H (ColH) plays a crucial role in rat islet isolation, whereas collagenase G (ColG) plays only a supporting role. We also showed that collagen III appears to be one of the key targets of ColH based on a mass spectrometry analysis. In the present study, we investigated whether our novel findings in an islet isolation model are universally applicable for other types of cell isolation, such as a hepatocyte isolation, with the use of enzyme blends of recombinant collagenases. METHODS: As the first step, the expression of one of the main matrix components, collagen III, on rat pancreatic and hepatic tissues was assessed with the use of immunohistochemical staining. ColG and ColH were expressed in recombinant E. coli carrying expression plasmids for each collagenase. Then the efficiency of the collagenase subtype on rat hepatocyte isolation was evaluated in terms of cell yield with the use of thermolysin combined with either ColG or ColH (n = 3, respectively). RESULTS: The expression of collagen III on rat hepatic tissues was dramatically lower than that of rat pancreatic tissues. In the rat hepatocyte isolation, a substantial amount of hepatocytes (0.81 ± 0.11 × 10(6)) were obtained in the ColG group, whereas almost no hepatocytes were retrieved in the ColH group, indicating that the influence of the collagenase subtypes in rat hepatocyte isolation are completely opposite to that observed in rat islet isolation. CONCLUSIONS: Considering that the expression of collagen III on hepatic tissues was relatively low and that almost no hepatocytes were retrieved when ColH and thermolysin were used, the present study supports our novel finding that collagen III appears to be one of the key targets of ColH in hepatocyte isolation. Therefore, the semiquantification of collagen III on the target tissues not only may positively contribute to efficient islet isolation, but also may affect other types of cell isolation by optimizing the ColH amount.


Assuntos
Separação Celular , Colágeno/metabolismo , Colagenases/metabolismo , Transplante das Ilhotas Pancreáticas , Ilhotas Pancreáticas/citologia , Animais , Hepatócitos/metabolismo , Pâncreas/metabolismo , Ratos Endogâmicos Lew , Termolisina
13.
Dis Aquat Organ ; 109(2): 127-37, 2014 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-24991740

RESUMO

A total of 74 phenotypically identified presumptive motile Aeromonas isolates recovered from septicaemic freshwater ornamental fish in Sri Lanka were genetically characterized by sequencing of rpoD and gyrB genes. rpoD/gyrB phylogeny confirmed only 53 isolates as Aeromonas, among which A. veronii was the predominant species (79.2%), followed by A. hydrophila (7.5%), A. caviae (5.7%), A. jandaei (1.9%), A. dhakensis (3.8%) and A. entero pelogenes (1.9%). The aeromonads confirmed by sequencing were further subjected to 16S rDNA PCR-RFLP which substantiated sequencing results for 83% of isolates. Fingerprinting of A. enteropelogenes (n = 42) using ERIC-PCR revealed no dominant clones, and the majority were genetically distinct. All isolates were screened by PCR for 7 virulence determinant genes (aer, act, ast, alt, fla, ser, exu) and 2 integrase encoding genes (intI1, intI2). Each isolate contained ≥3 of the virulence genes tested for, with a heterogeneous distribution. Of the isolates, 77% harboured the intI1 gene, while none had intI2. In vitro antimicrobial susceptibility testing showed highest resistances towards tetracycline (58.5%) and erythromycin (54.7%). Our results indicate the diverse range of aeromonads that could potentially be associated with motile aeromonad septicaemia in ornamental fish. This is the first isolation of A. dhakensis from a septicaemic ornamental fish since its original description from the same host.


Assuntos
Aeromonas/classificação , Aeromonas/efeitos dos fármacos , Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Infecções por Bactérias Gram-Negativas/veterinária , Sepse/veterinária , Animais , Impressões Digitais de DNA , DNA Bacteriano/genética , DNA Ribossômico/genética , Doenças dos Peixes/microbiologia , Peixes , Água Doce , Infecções por Bactérias Gram-Negativas/microbiologia , Filogenia , Filogeografia , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , RNA Ribossômico 16S/genética , Sepse/microbiologia
14.
Endoscopy ; 45(8): 635-42, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23807803

RESUMO

BACKGROUND AND STUDY AIMS: Despite the development of peroral video cholangioscopy (PVCS), no prospective multicenter studies have been undertaken to investigate the diagnostic accuracy of PVCS in biliary tract diseases. Therefore, the aim of this study was to clarify the accuracy of PVCS in evaluating biliary tract lesions. PATIENTS AND METHODS: This study was a prospective multicenter study at five tertiary referral centers in Japan and included 87 eligible patients with biliary tract diseases who underwent PVCS. The study evaluated the ability of PVCS to diagnose indeterminate biliary tract diseases, detect mucosal cancerous extension preoperatively in extrahepatic bile duct cancers, and predict adverse events. RESULTS: The use of PVCS appearance alone correctly distinguished benign from malignant indeterminate biliary lesions in 92.1 % of patients whereas biopsy alone was accurate in 85.7 %. In extrahepatic bile duct cancer, mucosal cancer extended histologically at least 20 mm in 34.7 % (17/49) of patients. The accuracy rate of PVCS to evaluate the presence or absence of mucosal cancerous extension by endoscopic retrograde cholangiography (ERC) alone, ERC with PVCS, and ERC with PVCS + biopsy were 73.5 %, 83.7 %, and 92.9 %, respectively. Adverse events were seen in 6.9 % of PVCS patients, but no serious complications were observed. CONCLUSION: PVCS enhanced the accurate diagnosis of biliary tract lesions by providing excellent resolution in combination with biopsy.


Assuntos
Neoplasias dos Ductos Biliares/patologia , Ductos Biliares Extra-Hepáticos/patologia , Endoscopia do Sistema Digestório , Neoplasias da Vesícula Biliar/patologia , Neoplasias Hepáticas/patologia , Mucosa/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias dos Ductos Biliares/complicações , Neoplasias dos Ductos Biliares/cirurgia , Ductos Biliares Extra-Hepáticos/cirurgia , Biópsia , Colangite/etiologia , Constrição Patológica/etiologia , Endoscopia do Sistema Digestório/efeitos adversos , Feminino , Neoplasias da Vesícula Biliar/complicações , Neoplasias da Vesícula Biliar/cirurgia , Hepatectomia , Humanos , Neoplasias Hepáticas/complicações , Neoplasias Hepáticas/cirurgia , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Pancreaticoduodenectomia , Sensibilidade e Especificidade , Tomografia Computadorizada por Raios X , Adulto Jovem
15.
Opt Express ; 21(6): 6889-94, 2013 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-23546071

RESUMO

n-channel body-tied partially depleted metal-oxide-semiconductor field-effect transistors (MOSFETs) were fabricated for large current applications on a silicon-on-insulator wafer with photonics-oriented specifications. The MOSFET can drive an electrical current as large as 20 mA. We monolithically integrated this MOSFET with a 2 × 2 Mach-Zehnder interferometer optical switch having thermo-optic phase shifters. The static and dynamic performances of the integrated device are experimentally evaluated.


Assuntos
Interferometria/instrumentação , Refratometria/instrumentação , Processamento de Sinais Assistido por Computador/instrumentação , Silício/química , Transistores Eletrônicos , Condutividade Elétrica , Desenho de Equipamento , Análise de Falha de Equipamento , Temperatura Alta , Fótons , Integração de Sistemas
16.
Biomech Model Mechanobiol ; 12(2): 325-33, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22584607

RESUMO

The mechanism of traumatic bone resorption in the denture-bearing bone has not yet been established with regard to the osteoclastic activity in relation to the mechanical stimulus. The purpose of this study was to clarify whether osteoclast appearance in maxilla depends on the strain intensity, using the murine loading model. The maxillary palate of thirteen-week-old male C57BL/6 mice was subjected to continuous pressure of 2 kPa (low stimulation, n = 4) or 7 kPa (high stimulation, n = 4) for 30 min/day for 7 consecutive days, and the mice were sacrificed after the last loading. The control group underwent the same protocol without load (n = 4). An animal-specific finite element model was constructed based on morphology and characteristics obtained from the micro-CT data and used to calculate the strain intensity of the bone. The bone histomorphometric technique revealed significant reduction of cortical bone volume and significant increase of bone resorption parameters such as osteoclast number in the bone tissue under the loading contact in comparison to the control (p < 0.05). The osteoclasts were observed in the subsurface region adjacent to the loading contact and the peripheral region of the marrow space in the intracortical region of the cortical bone in the mouse maxilla in both stimulation groups. An average of more than 90 % of the osteoclasts was observed in the areas with strain intensity higher than 85.0µ strain for the high stimulation group. The result suggests that the osteoclastic resorption is location-dependent and is also sensitive to the local strain intensity.


Assuntos
Análise de Elementos Finitos , Maxila/citologia , Osteoclastos/citologia , Estresse Mecânico , Animais , Masculino , Maxila/diagnóstico por imagem , Camundongos , Camundongos Endogâmicos C57BL , Padrões de Referência , Suporte de Carga , Microtomografia por Raio-X
17.
Int Endod J ; 46(1): 47-52, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22775227

RESUMO

AIM: To investigate the influence of elastic modulus mismatch between tooth and post and core restorations on mechanisms of root fracture. METHODOLOGY: Three-dimensional mathematical models of a root filled maxillary premolar tooth with supporting periodontium were constructed. The tooth was restored with a cast Ni-Cr alloy or fibre-reinforced composite post and core that was bonded or nonbonded to dentine. In the nonbonded simulation, a nonlinear contact analysis was executed to simulate a friction and a potential sliding phenomenon in the interface between tooth and post and core. Risks of root fracture and debonding at the bonded interface were estimated based on the principal stress of the root and the shear stress on the interface, respectively. RESULTS: The fracture risk of the bonded cast post and core was lower than that of the composite post and core, although the cast restoration exhibited eight times greater stress than the composite. The risk of root fracture based on the tensile stress of the tooth structures was higher with the bonded composite post and core than that with the cast post and core. These stresses doubled when the restorations were not bonded to the tooth structures. The risk of debonding of the cast post and core based on the shear stress was approximately twice that of the composite post and core. CONCLUSIONS: The elastic modulus mismatch appears to be a factor responsible for the debonding of post and cores from root canals, with the potential to increase the risk of root fracture indirectly.


Assuntos
Técnica para Retentor Intrarradicular , Fraturas dos Dentes/etiologia , Raiz Dentária/lesões , Dente não Vital/patologia , Adulto , Dente Pré-Molar/lesões , Dente Pré-Molar/patologia , Ligas de Cromo/química , Resinas Compostas/química , Simulação por Computador , Colagem Dentária/métodos , Materiais Dentários/química , Planejamento de Prótese Dentária , Cavidade Pulpar/patologia , Falha de Restauração Dentária , Dentina/patologia , Módulo de Elasticidade , Análise de Elementos Finitos , Fricção , Vidro/química , Guta-Percha/química , Humanos , Imageamento Tridimensional/métodos , Modelos Biológicos , Materiais Restauradores do Canal Radicular/química , Resistência ao Cisalhamento , Estresse Mecânico , Propriedades de Superfície , Resistência à Tração
18.
Arch Oral Biol ; 58(4): 377-83, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22776108

RESUMO

OBJECTIVE: Occlusal curvatures in human adult dentition such as the curve of Spee, curve of Wilson and Monsons's sphere provide clinical guidance for prosthetic rehabilitation and orthodontic treatment. However, association between occlusal curvature and masticatory function is not known. The aim of this study was to investigate the association between occlusal curvature and food comminuting and food mixing ability in human young adults with permanent dentitions. DESIGN: Fifty young adults with complete dentitions (mean age, 25.0 years) participated in the study. Occlusal curvature was determined by a three-dimensional analysis of the mandibular arch according to the Broadrick flag method. Food comminuting ability was assessed using a masticatory performance test with peanuts as test food and it was scored as median particle size. Food mixing ability was assessed using a mixing ability test with a two-coloured wax cube and it was scored as mixing ability index. RESULTS: A linear regression analysis identified the sphere radius of occlusal curvature as significant predictor for both median particle size and mixing ability index after controlling for maximum bite force (P<0.001). These results indicated that subjects with a flatter curvature (larger sphere) in the mandibular arch showed better food comminuting and mixing ability. Coefficient of determination (R(2)) of occlusal curvature related to median particle size and mixing ability index was comparable to that of maximum bite force. CONCLUSION: Occlusal curvature seems to be associated with food comminuting and mixing ability in human young adults with permanent dentitions.


Assuntos
Arco Dental/anatomia & histologia , Dentição Permanente , Má Oclusão Classe I de Angle/fisiopatologia , Mastigação/fisiologia , Adulto , Força de Mordida , Técnica de Fundição Odontológica , Feminino , Alimentos , Humanos , Masculino , Odontometria , Tamanho da Partícula , Análise de Regressão
19.
Oper Dent ; 38(3): 309-15, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23092147

RESUMO

The dimensional accuracy of optical bite registration in the CEREC system was compared to that of the conventional physical method in vitro using a bite registration material. Maxillary and mandibular full-arch dentate epoxy models mounted on an articulator were used to measure the interarch distance and the angles created by the occlusal planes. The preparations for a single restoration on the maxillary first molar or for multiple restorations on the maxillary posterior quadrant were made on the model. Optical impression and bite registration data were collected to construct virtual models using computer-aided design software. A silicone material was used for the physical method, and the dimensional accuracy was measured by means of the coordinate measuring machine. The discrepancy relative to the baseline before preparation was analyzed in each registration record. For the single restoration, the optical method created a mean discrepancy of 243.2 µm relative to baseline at the prepared tooth, which was insignificantly but slightly lower than the mean discrepancy of 311.1 µm obtained with the physical method. The mean rotational deviation in the horizontal plane was significantly lower for the optical method. For the multiple preparations, the optical method showed significantly larger discrepancy on the right molar and on the left premolar and molar sites. In the frontal view, the optical method created significantly larger rotational deviation than the physical method. The result indicates that the optical bite registration was effective in terms of dimensional accuracy for single posterior restorations.


Assuntos
Desenho Assistido por Computador , Restauração Dentária Permanente/métodos , Imageamento Tridimensional/métodos , Registro da Relação Maxilomandibular/métodos , Imagem Óptica/métodos , Dente Pré-Molar/anatomia & histologia , Coroas , Arco Dental/anatomia & histologia , Articuladores Dentários , Materiais Dentários/química , Resinas Epóxi/química , Marcadores Fiduciais , Humanos , Mandíbula/anatomia & histologia , Maxila/anatomia & histologia , Modelos Dentários , Dente Molar/anatomia & histologia , Rotação , Silicones/química , Propriedades de Superfície , Preparo Prostodôntico do Dente/métodos , Interface Usuário-Computador
20.
Adv Med Sci ; 57(2): 244-50, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23183766

RESUMO

PURPOSE: This study was aimed to investigate etiology and clinical profiles of recurrent acute pancreatitis (RAP), particularly from the morphology of the pancreaticobiliary duct system. MATERIAL AND METHODS: Pancreaticobiliary morphology was examined in 230 of 381 patients with acute pancreatitis (AP) using endoscopic retrograde cholangiopancreatography. We analyzed factors associated with RAP including the pancreaticobiliary duct system. RESULTS: RAP was diagnosed in 74 patients (19%). Major etiologies of RAP were alcoholic (38%), idiopathic (26%) and pancreaticobiliary malformation (22%). Patients with alcoholic RAP were significantly younger (47.2±11.6 years) than those with gallstone RAP (67.3±16.8; p<0.05). RAP with pancreaticobiliary malformation (male-to-female ratio: 1:4.3; p<0.01) and gallstone RAP (1:1.7; p<0.05) occurred predominantly in females in comparison with alcoholic RAP (1:0.2). Recurrence rate was 80% for AP with pancreaticobiliary malformation, significantly higher than for the others (p<0.01). Pancreas divisum was suspected as the etiology of mild RAP in 7 patients. Four RAP patients with pancreas divisum underwent endoscopic minor papilla sphincterotomy and improved. Pancreaticobiliary maljunction with biliary dilatation (choledochal cyst) was suspected as the etiology of mild RAP in 3 patients. The 3 RAP patients with choledochal cyst underwent prophylactic flow diversion surgery with complete resection of the dilated common bile duct, and achieved improvement. High confluence of pancreaticobiliary ducts was suspected as the etiology of mild RAP in 6 patients. CONCLUSION: Pancreaticobiliary malformation is one of the major causes of RAP. As some of them benefit from endoscopic or surgical treatment, morphology of the pancreaticobiliary duct system should be examined where possible in RAP patients.


Assuntos
Ductos Biliares/anormalidades , Ductos Pancreáticos/anormalidades , Pancreatite/etiologia , Doença Aguda , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Colangiopancreatografia Retrógrada Endoscópica , Cisto do Colédoco/complicações , Cisto do Colédoco/cirurgia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pancreatite/cirurgia , Recidiva , Esfinterotomia Endoscópica , Adulto Jovem
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