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1.
Front Mol Neurosci ; 16: 1147951, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37293540

RESUMO

Neonatal maternal separation is a widely used method to construct an early-life stress model in rodents. In this method, pups are separated from their mothers for several hours every day during the first 2 weeks of life, which results in adverse early-life events. It is a known fact that maternal separation can exert a significant impact on the behavior and psychological health, such as anxiety and depression, in adolescent offspring. However, environmental conditions during maternal separation can differ such as the presence of other animals or by placing pups in a different dam. To investigate the differential effects of various conditions of maternal separation on the behavior of adolescent mice, we created the following groups: (1) iMS group: pups were moved to an isolated room with no other adult mice in a nearby cage, (2) eDam group: the pups randomly exchanged their dams, (3) OF group: pups were shifted to another cage with the bedding material containing maternal odor (olfactory stimulation), and (4) MS group: pups were shifted to another vivarium. From postnatal day (PND) 2-20 (i.e., 19 consecutive days), pups were separated from the dam daily for 4 h and exposed to various environments (MS, iMS, eDam, and OF) or were left undisturbed [control (CON) group]. A series of behavioral assessments were conducted to evaluate locomotion, anxiety, recognition, learning, and memory in adolescent offspring. The results showed that neonatal maternal separation led to impaired recognition memory, motor coordination, and motor skill learning across all groups. However, the iMS group exhibited anxiety-like behavior in the elevated plus maze test and enhanced the extinction of fear memory in the auditory fear conditioning test. The OF and eDam groups displayed partially recovered short-term working memory in the Y-maze test but exhibited opposite exploratory behaviors. The OF group spent more time in the center, while the eDam group spent less time. These findings demonstrated that exposure to different environmental conditions during maternal separation causes behavioral alterations in adolescent offspring, providing a potential explanation for the variation in behavioral phenotypes observed in the early-life stress models.

2.
Prev Med ; 172: 107550, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37210044

RESUMO

Little is known about the association of cancer information seeking behavior with cigarette smoking and e-cigarette use. A multi-year cross-sectional analysis using a pooled data of the Health Information National Trends Survey 5, Cycles 1-4 (2017-2020) was conducted. To examine the association of cancer information seeking behavior with current cigarette smoking (currently smoke every day/some days among individuals who smoked 100+ cigarettes in lifetime) and e-cigarette use (currently use every day/some days among lifetime users) in nationally representative U.S. adults, we conducted weighted multiple logistic regression analysis, adjusting for sex, race/ethnicity, age, obese status, depressed mood, cancer diagnosis history, metropolitan status, and survey year. The regression models were stratified by education level (

Assuntos
Fumar Cigarros , Sistemas Eletrônicos de Liberação de Nicotina , Neoplasias , Vaping , Humanos , Adulto , Adolescente , Adulto Jovem , Estudos Transversais , Comportamento de Busca de Informação , Escolaridade , Neoplasias/epidemiologia
3.
Sensors (Basel) ; 22(13)2022 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-35808342

RESUMO

The motion capture method using sparse inertial sensors is an approach for solving the occlusion and economic problems in vision-based methods, which is suitable for virtual reality applications and works in complex environments. However, VR applications need to track the location of the user in real-world space, which is hard to obtain using only inertial sensors. In this paper, we present Fusion Poser, which combines the deep learning-based pose estimation and location tracking method with six inertial measurement units and a head tracking sensor that provides head-mounted displays. To estimate human poses, we propose a bidirectional recurrent neural network with a convolutional long short-term memory layer that achieves higher accuracy and stability by preserving spatio-temporal properties. To locate a user with real-world coordinates, our method integrates the results of an estimated joint pose with the pose of the tracker. To train the model, we gathered public motion capture datasets of synthesized IMU measurement data, as well as creating a real-world dataset. In the evaluation, our method showed higher accuracy and a more robust estimation performance, especially when the user adopted lower poses, such as a squat or a bow.


Assuntos
Redes Neurais de Computação , Postura , Humanos , Movimento (Física)
4.
Sensors (Basel) ; 21(9)2021 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-33925833

RESUMO

Electromagnetic responses are generally controlled electrically or optically. However, although electrical and optical control allows fast response, they suffer from switching or tuning range limitations. This paper controls electromagnetic response by mechanical transformation. We introduce a novel kirigami-inspired structure for mechanical transformation with less strength, integrating a shape memory alloy actuator into the kirigami-inspired for mechanical transformation and hence electromagnetic control. The proposed approach was implemented for a reconfigurable antenna designed based on structural and electromagnetic analyses. The mechanical transformation was analyzed with thermal stimulus to predict the antenna geometry and electromagnetic analysis with different geometries predicted antenna performance. We numerically and experimentally verified that resonance response was thermally controlled using the kirigami-inspired antenna integrated with a shape memory alloy actuator.

5.
Sci Rep ; 10(1): 18227, 2020 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-33106552

RESUMO

The myristoylated zeta inhibitory peptide (ZIP), which was originally developed as a protein kinase C/Mζ (PKCζ/PKMζ) inhibitor, is known to produce the loss of different forms of memories. However, ZIP induces memory loss even in the absence of PKMζ, and its mechanism of action, therefore, remains elusive. Here, through a kinome-wide screen, we found that glycogen synthase kinase 3 beta (GSK-3ß) was robustly activated by ZIP in vitro. ZIP induced depotentiation (a cellular substrate of memory erasure) of conditioning-induced potentiation at LA synapses, and the ZIP-induced depotentiation was prevented by a GSK-3ß inhibitor, 6-bromoindirubin-3-acetoxime (BIO-acetoxime). Consistently, GSK-3ß inhibition by BIO-acetoxime infusion or GSK-3ß knockdown by GSK-3ß shRNA in the LA attenuated ZIP-induced disruption of learned fear. Furthermore, conditioned fear was decreased by expression of a non-inhibitable form of GSK-3ß in the LA. Our findings suggest that GSK-3ß activation is a critical step for ZIP-induced disruption of memory.


Assuntos
Peptídeos Penetradores de Células/farmacologia , Medo/fisiologia , Glicogênio Sintase Quinase 3 beta/metabolismo , Aprendizagem/fisiologia , Lipopeptídeos/farmacologia , Memória/fisiologia , Proteína Quinase C/antagonistas & inibidores , Animais , Medo/efeitos dos fármacos , Aprendizagem/efeitos dos fármacos , Masculino , Memória/efeitos dos fármacos , Modelos Animais , Fosforilação , Ratos , Ratos Sprague-Dawley , Transdução de Sinais
6.
Mol Brain ; 13(1): 16, 2020 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-32024548

RESUMO

The return of fear following extinction therapy is an important issue associated with the treatment of many fear-related disorders. Fear renewal is a suitable model, with which context-dependent modulation of the fear response can be examined. In this model, any context outside of an extinction context (e.g., novel or familiar contexts) could evoke relapse of the fear response. However, brain regions associated with context-dependent modulation are not fully understood. The posterior parietal cortex (PPC) is considered a center for integrating multisensory information and making decisions. To study its role in the contextual modulation of fear relapse, we reversibly inactivated the PPC in mice before they were exposed to various contexts after extinction training. When muscimol was infused into the PPC, fear renewal was impaired in a novel context, but not in a familiar context. Fear relapses were blocked during optogenetic inhibition of the PPC, only when animals were placed in a novel context. We propose that the neural activity of the PPC is necessary for the relapse of a precise response to an extinguished conditioned stimulus in a novel context.


Assuntos
Medo/fisiologia , Muscimol/farmacologia , Lobo Parietal/fisiologia , Estimulação Acústica , Animais , Condicionamento Clássico/fisiologia , Sinais (Psicologia) , Tomada de Decisões , Eletrochoque , Extinção Psicológica , Reação de Congelamento Cataléptica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Optogenética , Lobo Parietal/efeitos dos fármacos
7.
Neuroendocrinology ; 110(11-12): 1010-1027, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31935735

RESUMO

INTRODUCTION: Synchronous and pulsatile neural activation of kisspeptin neurons in the arcuate nucleus (ARN) are important components of the gonadotropin-releasing hormone pulse generator, the final common pathway for central regulation of mammalian reproduction. However, whether ARN kisspeptin neurons can intrinsically generate self-sustained synchronous oscillations from the early neonatal period and how they are regulated remain unclear. OBJECTIVE: This study aimed to examine the endogenous rhythmicity of ARN kisspeptin neurons and its neural regulation using a neonatal organotypic slice culture model. METHODS: We monitored calcium (Ca2+) dynamics in real-time from individual ARN kisspeptin neurons in neonatal organotypic explant cultures of Kiss1-IRES-Cre mice transduced with genetically encoded Ca2+ indicators. Pharmacological approaches were employed to determine the regulations of kisspeptin neuron-specific Ca2+ oscillations. A chemogenetic approach was utilized to assess the contribution of ARN kisspeptin neurons to the population dynamics. RESULTS: ARN kisspeptin neurons in neonatal organotypic cultures exhibited a robust synchronized Ca2+ oscillation with a period of approximately 3 min. Kisspeptin neuron-specific Ca2+ oscillations were dependent on voltage-gated sodium channels and regulated by endoplasmic reticulum-dependent Ca2+ homeostasis. Chemogenetic inhibition of kisspeptin neurons abolished synchronous Ca2+ oscillations, but the autocrine actions of the neuropeptides were marginally effective. Finally, neonatal ARN kisspeptin neurons were regulated by N-methyl-D-aspartate and gamma-aminobutyric acid receptor-mediated neurotransmission. CONCLUSION: These data demonstrate that ARN kisspeptin neurons in organotypic cultures can generate synchronized and self-sustained Ca2+ oscillations. These oscillations controlled by multiple regulators within the ARN are a novel ultradian rhythm generator that is active during the early neonatal period.


Assuntos
Núcleo Arqueado do Hipotálamo/fisiologia , Sinalização do Cálcio/fisiologia , Kisspeptinas , Neurônios/fisiologia , Ritmo Ultradiano/fisiologia , Animais , Animais Recém-Nascidos , Camundongos , Camundongos Transgênicos
8.
Demography ; 56(3): 969-990, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30903481

RESUMO

An important factor speculated to affect fertility level is education. Theoretical predictions regarding whether education increases or decreases fertility are ambiguous. This study analyzes the causal impact of higher education on fertility using census data administered by Statistics Korea. To account for the endogeneity of education, this study exploits the Korean higher education reform initiated in 1993 that boosted women's likelihood of graduating from college. Based on regression kink designs, we find that having a college degree reduces the likelihood of childbirths by 23 percentage points and the total number of childbirths by 1.3. Analyses of possible mechanisms show that labor market-related factors are a significant channel driving the negative effects; female college graduates are more likely to be wage earners and more likely to have high-wage occupations.


Assuntos
Sucesso Acadêmico , Paridade , Adulto , Feminino , Humanos , Renda , República da Coreia , Fatores Socioeconômicos
9.
IEEE Trans Vis Comput Graph ; 25(4): 1746-1759, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29993781

RESUMO

When motion capture data is applied to virtual characters, the applied motion often exhibits geometric and physical errors, which necessitates a cumbersome refinement process. We present a novel framework to efficiently obtain a corrected motion as well as its supporting contact information from multi-contact motion capture data. To this end, first, we present a projective dynamics-based method for optimizing character motions. By carefully defining objective functions and constraints using differential representation of motions, we develop a highly efficient motion optimizer that can create geometrically and dynamically adjusted motions given reference motion data and contact information. Second, we develop a contact optimizer that finds a set of contacts that allows the motion optimizer to generate a motion that best follows the reference motion under dynamic and geometric constraints. This is achieved by iteratively improving the hypothesis on the best set of contacts by getting feedback from the motion optimizer. We demonstrate that our method significantly improves the naturalness of a wide range of motion capture data, from walking to rolling.

10.
Biochem Biophys Res Commun ; 506(3): 492-497, 2018 11 30.
Artigo em Inglês | MEDLINE | ID: mdl-30361088

RESUMO

Amyloid beta (Aß) is known to be one of the strong candidate molecules for initiating Alzheimer's disease and has been extensively studied in the light of disease pathophysiology. However, it is still elusive what roles Aß play in the normal brain. In this study, we report that Aß is required for memory forgetting in the normal brain. We monitored object recognition memory, and in order to quench soluble Aß, we microinjected anti-Aß antibody (4G8) into the ventricles after memory acquisition. Microinjection of anti-Aß antibody prolonged the maintenance of object recognition memory. This effect appeared not to be due to modulation of memory consolidation since antibody injection after memory consolidation still had a similar effect on memory maintenance. Furthermore, the maintenance of object recognition memory was prolonged in Fcgr2b KO mice, which lacks IgG Fcγ receptor II-b (FcγRIIb), a receptor for soluble Aß oligomers. Taken together, these findings suggest that endogenous Aß is involved in memory forgetting in the normal brain.


Assuntos
Peptídeos beta-Amiloides/metabolismo , Encéfalo/metabolismo , Memória , Animais , Masculino , Camundongos Knockout , Microinjeções , Testes de Neutralização
11.
J Adv Prosthodont ; 9(5): 321-327, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29142638

RESUMO

PURPOSE: The aim of this study was to investigate dental arch dimensions and to classify arch shape in Korean young adults. MATERIALS AND METHODS: The sample included 50 Koreans with age ranging from 24 to 32 years. Maxillary and mandibular casts were fabricated using irreversible hydrocolloid and type III dental stones. Incisor-canine distance, incisor-1st molar distance, incisor-2nd molar distance, intercanine distance, inter-1st molar distance, and inter-2nd molar distance in both the maxillary and mandibular arch were measured using a three-dimensional measuring device. The dental arch was classified into three groups using five ratios from the measured values by the K-means clustering method. The data were analyzed with one-way analysis of variance. RESULTS: Arch lengths (IM2D, incisal-2nd molar distance) were 44.13 mm in the maxilla and 40.40 mm in the mandible. Arch widths (M2W, inter 2nd molar width) were 64.12 mm in the maxilla and 56.37 mm in the mandible. Distribution of the dental arch form was mostly ovoid shape (maxilla 52% and mandible 56%), followed by the V-shape and the U-shape. The arch width for the U-shape was broader than for the other forms. CONCLUSION: This study establishes new reference data for dental arch dimensions for young Korean adults. The most common arch form is the ovoid type in the maxilla and mandible of Koreans. Clinicians should be aware of these references and classify arch type before and during their dental treatment for effective and harmonized results in Koreans.

12.
J Periodontal Implant Sci ; 47(5): 273-291, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29093986

RESUMO

PURPOSE: Although static magnetic fields (SMFs) have been used in dental prostheses and osseointegrated implants, their biological effects on osteoblastic and cementoblastic differentiation in cells involved in periodontal regeneration remain unknown. This study was undertaken to investigate the effects of SMFs (15 mT) on the osteoblastic and cementoblastic differentiation of human osteoblasts, periodontal ligament cells (PDLCs), and cementoblasts, and to explore the possible mechanisms underlying these effects. METHODS: Differentiation was evaluated by measuring alkaline phosphatase (ALP) activity, mineralized nodule formation based on Alizarin red staining, calcium content, and the expression of marker mRNAs assessed by reverse transcription polymerase chain reaction (RT-PCR). Signaling pathways were analyzed by western blotting and immunocytochemistry. RESULTS: The activities of the early marker ALP and the late markers matrix mineralization and calcium content, as well as osteoblast- and cementoblast-specific gene expression in osteoblasts, PDLCs, and cementoblasts were enhanced. SMFs upregulated the expression of Wnt proteins, and increased the phosphorylation of glycogen synthase kinase-3ß (GSK-3ß) and total ß-catenin protein expression. Furthermore, p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK), and nuclear factor-κB (NF-κB) pathways were activated. CONCLUSIONS: SMF treatment enhanced osteoblastic and/or cementoblastic differentiation in osteoblasts, cementoblasts, and PDLCs. These findings provide a molecular basis for the beneficial osteogenic and/or cementogenic effect of SMFs, which could have potential in stimulating bone or cementum formation during bone regeneration and in patients with periodontal disease.

13.
J Adv Prosthodont ; 9(4): 315-320, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28875000

RESUMO

PURPOSE: The aim of this investigation was to analyze the dimensions of clinical crowns and to classify the crown and the gingival type in the anterior teeth in Korean young adults. MATERIALS AND METHODS: Casts were obtained from 50 subjects ranging in age from 24 to 32. Measurements of length and width were made on the casts using a pair of digital calipers on the entire dentition. Crown thickness and papilla height were also measured and MDW/CL (mesiodistal width to clinical length) and CW/CL (cervical width to clinical length) ratios of the maxillary anterior teeth were calculated. The K-clustering method was used for CW/CL to classify the anterior tooth shape into three groups (tapered, ovoid, and square), and one-way analysis of variance and Duncan's post-hoc comparison were used to evaluate statistical significance between the groups. Pearson's correlation analysis was performed between tooth shape and papillary height (PH) to demonstrate the correlation between tooth shape and gingival morphological characteristics. RESULTS: The average length of the maxillary central incisors was 9.89 mm; the mesio-distal width was 8.54 mm; and the ratio of width/length was 0.86 in Korean young adults. The average bucco-palatal thickness of the central incisor was 3.14 mm at the incisal 1/3 aspect. Ovoid type was the most common tooth shape (48%), followed by square type (29%) and taper type (23%) in the central incisors of Korean young adults. Tooth shape and gingival type were correlated with each other. CONCLUSION: New reference data were established for tooth size in Korean young adults and the data show several patterns of tooth shape and gingival type. Clinicians should diagnose and treat based on these characteristics for better results in the Korean population.

14.
J Med Internet Res ; 19(8): e272, 2017 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-28768609

RESUMO

BACKGROUND: While online health social networks (OHSNs) serve as an effective platform for patients to fulfill their various social support needs, predicting the needs of users and providing tailored information remains a challenge. OBJECTIVE: The objective of this study was to discriminate important features for identifying users' social support needs based on knowledge gathered from survey data. This study also provides guidelines for a technical framework, which can be used to predict users' social support needs based on raw data collected from OHSNs. METHODS: We initially conducted a Web-based survey with 184 OHSN users. From this survey data, we extracted 34 features based on 5 categories: (1) demographics, (2) reading behavior, (3) posting behavior, (4) perceived roles in OHSNs, and (5) values sought in OHSNs. Features from the first 4 categories were used as variables for binary classification. For the prediction outcomes, we used features from the last category: the needs for emotional support, experience-based information, unconventional information, and medical facts. We compared 5 binary classifier algorithms: gradient boosting tree, random forest, decision tree, support vector machines, and logistic regression. We then calculated the scores of the area under the receiver operating characteristic (ROC) curve (AUC) to understand the comparative effectiveness of the used features. RESULTS: The best performance was AUC scores of 0.89 for predicting users seeking emotional support, 0.86 for experience-based information, 0.80 for unconventional information, and 0.83 for medical facts. With the gradient boosting tree as our best performing model, we analyzed the strength of individual features in predicting one's social support need. Among other discoveries, we found that users seeking emotional support tend to post more in OHSNs compared with others. CONCLUSIONS: We developed an initial framework for automatically predicting social support needs in OHSNs using survey data. Future work should involve nonsurvey data to evaluate the feasibility of the framework. Our study contributes to providing personalized social support in OHSNs.


Assuntos
Rede Social , Apoio Social , Telemedicina/métodos , Feminino , Comportamentos Relacionados com a Saúde , Humanos , Masculino
15.
Elife ; 62017 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-28671550

RESUMO

There has been a longstanding debate on whether original fear memory is inhibited or erased after extinction. One possibility that reconciles this uncertainty is that the inhibition and erasure mechanisms are engaged in different phases (early or late) of extinction. In this study, using single-session extinction training and its repetition (multiple-session extinction training), we investigated the inhibition and erasure mechanisms in the prefrontal cortex and amygdala of rats, where neural circuits underlying extinction reside. The inhibition mechanism was prevalent with single-session extinction training but faded when single-session extinction training was repeated. In contrast, the erasure mechanism became prevalent when single-session extinction training was repeated. Moreover, ablating the intercalated neurons of amygdala, which are responsible for maintaining extinction-induced inhibition, was no longer effective in multiple-session extinction training. We propose that the inhibition mechanism operates primarily in the early phase of extinction training, and the erasure mechanism takes over after that.


Assuntos
Tonsila do Cerebelo/fisiologia , Extinção Psicológica , Medo , Córtex Pré-Frontal/fisiologia , Animais , Condicionamento Clássico , Ratos
16.
Clin Oral Implants Res ; 28(4): 396-405, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26972335

RESUMO

OBJECTIVES: The aim of this study was to investigate the effects of static magnetic fields (SMFs) on bone regeneration around titanium implants by µCT, histologic analysis, microarrays, and quantitative real-time PCR (qRT-PCR). MATERIALS AND METHODS: Neodymium magnets provided the source of SMFs, the specimens were grade 5 titanium implants, and the animals were twenty-seven adult male New Zealand white rabbits. These implants were divided into six groups according to the presence of a magnet and predetermined healing period (1, 4, and 8 weeks). Each group comprised six specimens for µCT (n = 6) and histologic examination, and three specimens (n = 3) for microarrays and qRT-PCR, yielding a total of 54 specimens. RESULTS: The µCT data showed that SMFs increased bone volume fraction (bone volume/total volume, BV/TV), trabecular number (Tb.N), and trabecular thickness (Tb.Th). Histologic observation indicated that SMFs promoted new bone formation and direct bony contact with implants. Microarray analysis identified 293 genes upregulated (>twofold) in response to SMFs. The upregulated genes included extracellular matrix (ECM)-related genes (COL10A1, COL9A1, and COL12A1) and growth factor (GF)-related genes (CTGF and PDGFD), and the upregulation was confirmed by qRT-PCR. Gene Ontology (GO) and pathway analysis revealed the involvement of the mitogen-activated protein kinase (MAPK), Wnt, and PPAR-gamma signaling pathways in implant healing. CONCLUSIONS: µCT, histology, microarrays, and real-time PCR indicate that SMFs could be an effective approach to improving bone regeneration around dental implants.


Assuntos
Regeneração Óssea/fisiologia , Implantes Dentários , Magnetoterapia/métodos , Titânio , Animais , Masculino , Coelhos , Reação em Cadeia da Polimerase em Tempo Real , Análise Serial de Tecidos , Microtomografia por Raio-X
17.
IEEE Trans Vis Comput Graph ; 23(1): 551-560, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27875171

RESUMO

The Information Visualization community has begun to pay attention to visualization literacy; however, researchers still lack instruments for measuring the visualization literacy of users. In order to address this gap, we systematically developed a visualization literacy assessment test (VLAT), especially for non-expert users in data visualization, by following the established procedure of test development in Psychological and Educational Measurement: (1) Test Blueprint Construction, (2) Test Item Generation, (3) Content Validity Evaluation, (4) Test Tryout and Item Analysis, (5) Test Item Selection, and (6) Reliability Evaluation. The VLAT consists of 12 data visualizations and 53 multiple-choice test items that cover eight data visualization tasks. The test items in the VLAT were evaluated with respect to their essentialness by five domain experts in Information Visualization and Visual Analytics (average content validity ratio = 0.66). The VLAT was also tried out on a sample of 191 test takers and showed high reliability (reliability coefficient omega = 0.76). In addition, we demonstrated the relationship between users' visualization literacy and aptitude for learning an unfamiliar visualization and showed that they had a fairly high positive relationship (correlation coefficient = 0.64). Finally, we discuss evidence for the validity of the VLAT and potential research areas that are related to the instrument.

18.
J Adv Prosthodont ; 8(5): 388-395, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27826389

RESUMO

PURPOSE: The purpose of this study was to evaluate the resistance to deformation under static overloading by measuring yield and fracture strength, and to analyze the failure characteristics of implant assemblies made of different titanium grades and connections. MATERIALS AND METHODS: Six groups of implant assemblies were fabricated according to ISO 14801 (n=10). These consisted of the combinations of 3 platform connections (external, internal, and morse tapered) and 2 materials (titanium grade 2 and titanium grade 4). Yield strength and fracture strength were evaluated with a computer-controlled Universal Testing Machine, and failed implant assemblies were classified and analyzed by optical microscopy. The data were analyzed using the One-way analysis of variance (ANOVA) and Student's t-test with the level of significance at P=.05. RESULTS: The group IT4S had the significantly highest values and group IT2 the lowest, for both yield strength and fracture strength. Groups IT4N and ET4 had similar yield and fracture strengths despite having different connection designs. Group MT2 and group IT2 had significant differences in yield and fracture strength although they were made by the same material as titanium grade 2. The implant system of the similar fixture-abutment interfaces and the same materials showed the similar characteristics of deformation. CONCLUSION: A longer internal connection and titanium grade 4 of the implant system is advantageous for static overloading condition. However, it is not only the connection design that affects the stability. The strength of the titanium grade as material is also important since it affects the implant stability. When using the implant system made of titanium grade 2, a larger diameter fixture should be selected in order to provide enough strength to withstand overloading.

19.
Dent Mater ; 32(11): 1394-1405, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27671470

RESUMO

OBJECTIVE: Although cobalt-chromium (Co-Cr) dental alloys are routinely used in prosthodontics, the biocompatibility of Co-Cr alloys is controversial. The aims of the present study were to investigate the effects of Co-Cr alloys on human gingival fibroblasts (HGF) and osteoblasts in an in vitro model as well as their potential molecular mechanisms, focusing on NF-E2-related factor 2 (Nrf2) pathways. METHODS: Cells were directly seeded on prepared Co-Cr alloy discs (15.0mm diameter, 1.0mm thickness) or indirectly treated with Co-Cr alloy located at the bottom of an insert well and incubated for 3 days. Cytotoxicity and reactive oxygen species (ROS) production was evaluated by MTS assay and flow cytometry, respectively. Protein and mRNA levels were determined by Western blotting and RT-PCR analysis, respectively. RESULTS: Cell viability and flow cytometric assay demonstrated that the Co-Cr alloy was cytotoxic to HGFs and osteoblasts, and significantly increased ROS production. In addition, the Co-Cr alloys upregulated pro-inflamamtory cytokines (TNF-α, IL-1ß, IL-6, and IL-8) and increased levels of various inflammatory mediators (iNOS derived nitrite oxide, and COX-2-derived PGE2) in both cells. A mechanistic study showed that Co-Cr alloys activates the NRF2 pathway and up-regulate antioxidant enzymes including heme oxygenase-1 (HO-1). Co-Cr alloys activated JAK2/STAT3, p38/ERK/JNK MAPKs and NF-κB signaling pathways. Furthermore, antioxidants (resveratrol and NAC) and HO-1 inhibitor (SnPP) significantly inhibited the production of ROS and inflammatory mediators, as well as the activation of NF-κB signaling in Co-Cr alloy stimulated HGFs and osteoblasts. SIGNIFICANCE: This study is the first to show that Co-Cr alloys exert cytotoxic and inflammatory effects via activation of Nrf2/ARE signaling and up-regulation of downstream HO-1, which could represent candidate targets for the regulation of inflammatory responses to Co-Cr alloys.


Assuntos
Ligas de Cromo/toxicidade , Cobalto/toxicidade , Ligas Dentárias/toxicidade , Gengiva/citologia , Fator 2 Relacionado a NF-E2/efeitos dos fármacos , Antioxidantes , Materiais Biocompatíveis , Fibroblastos , Humanos , Osteoblastos , Transdução de Sinais
20.
Sci Rep ; 6: 31069, 2016 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-27488731

RESUMO

Various auditory tones have been used as conditioned stimuli (CS) for fear conditioning, but researchers have largely neglected the effect that different types of auditory tones may have on fear memory processing. Here, we report that at lateral amygdala (LA) synapses (a storage site for fear memory), conditioning with different types of auditory CSs (2.8 kHz tone, white noise, FM tone) recruits distinct forms of long-term potentiation (LTP) and inserts calcium permeable AMPA receptor (CP-AMPAR) for variable periods. White noise or FM tone conditioning produced brief insertion (<6 hr after conditioning) of CP-AMPARs, whereas 2.8 kHz tone conditioning induced more persistent insertion (≥6 hr). Consistently, conditioned fear to 2.8 kHz tone but not to white noise or FM tones was erased by reconsolidation-update (which depends on the insertion of CP-AMPARs at LA synapses) when it was performed 6 hr after conditioning. Our data suggest that conditioning with different auditory CSs recruits distinct forms of LA synaptic plasticity, resulting in more malleable fear memory to some tones than to others.


Assuntos
Tonsila do Cerebelo/fisiologia , Medo/fisiologia , Estimulação Acústica , Animais , Condicionamento Psicológico , Técnicas In Vitro , Potenciação de Longa Duração , Masculino , Plasticidade Neuronal , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-Dawley , Receptores de AMPA/metabolismo , Som
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