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1.
Biomimetics (Basel) ; 9(3)2024 Mar 03.
Artigo em Inglês | MEDLINE | ID: mdl-38534843

RESUMO

Nighttime object detection is challenging due to dim, uneven lighting. The IIHS research conducted in 2022 shows that pedestrian anti-collision systems are less effective at night. Common solutions utilize costly sensors, such as thermal imaging and LiDAR, aiming for highly accurate detection. Conversely, this study employs a low-cost 2D image approach to address the problem by drawing inspiration from biological dark adaptation mechanisms, simulating functions like pupils and photoreceptor cells. Instead of relying on extensive machine learning with day-to-night image conversions, it focuses on image fusion and gamma correction to train deep neural networks for dark adaptation. This research also involves creating a simulated environment ranging from 0 lux to high brightness, testing the limits of object detection, and offering a high dynamic range testing method. Results indicate that the dark adaptation model developed in this study improves the mean average precision (mAP) by 1.5-6% compared to traditional models. Our model is capable of functioning in both twilight and night, showcasing academic novelty. Future developments could include using virtual light in specific image areas or integrating with smart car lighting to enhance detection accuracy, thereby improving safety for pedestrians and drivers.

2.
Diagnostics (Basel) ; 12(5)2022 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-35626222

RESUMO

The management of peptic ulcer bleeding is clinically challenging. For decades, the Forrest classification has been used for risk stratification for nonvariceal ulcer bleeding. The perception and interpretation of the Forrest classification vary among different endoscopists. The relationship between the bleeder and ulcer images and the different stages of the Forrest classification has not been studied yet. Endoscopic still images of 276 patients with peptic ulcer bleeding for the past 3 years were retrieved and reviewed. The intra-rater agreement and inter-rater agreement were compared. The obtained endoscopic images were manually drawn to delineate the extent of the ulcer and bleeding area. The areas of the region of interest were compared between the different stages of the Forrest classification. A total of 276 images were first classified by two experienced tutor endoscopists. The images were reviewed by six other endoscopists. A good intra-rater correlation was observed (0.92-0.98). A good inter-rater correlation was observed among the different levels of experience (0.639-0.859). The correlation was higher among tutor and junior endoscopists than among experienced endoscopists. Low-risk Forrest IIC and III lesions show distinct patterns compared to high-risk Forrest I, IIA, or IIB lesions. We found good agreement of the Forrest classification among different endoscopists in a single institution. This is the first study to quantitively analyze the obtained and explain the distinct patterns of bleeding ulcers from endoscopy images.

3.
J Clin Med ; 10(16)2021 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-34441823

RESUMO

With the decreasing incidence of peptic ulcer bleeding (PUB) over the past two decades, the clinician experience of managing patients with PUB has also declined, especially for young endoscopists. A patient with PUB management requires collaborative care involving the emergency department, gastroenterologist, radiologist, and surgeon, from initial assessment to hospital discharge. The application of artificial intelligence (AI) methods has remarkably improved people's lives. In particular, AI systems have shown great potential in many areas of gastroenterology to increase human performance. Colonoscopy polyp detection or diagnosis by an AI system was recently introduced for commercial use to improve endoscopist performance. Although PUB is a longstanding health problem, these newly introduced AI technologies may soon impact endoscopists' clinical practice by improving the quality of care for these patients. To update the current status of AI application in PUB, we reviewed recent relevant literature and provided future perspectives that are required to integrate such AI tools into real-world practice.

4.
Medicine (Baltimore) ; 100(14): e25299, 2021 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-33832099

RESUMO

ABSTRACT: Intradialytic hypotension (IDH) may lead to a poor life quality and was associated with cardiovascular mortality in patients under hemodialysis. This study investigated the autonomic nerve and cardiovascular function in the IDH episodes.In this case-control study, 70 end stage renal disease patients (198 visits) were recruited. Pulse wave analysis and heart rate variability were evaluated before hemodialysis. Two definitions of IDH were confirmed by medical records. IDH-f indicated a drop of systolic blood pressure or mean arterial pressure, accompanied with symptoms; IDH-n indicated a low nadir systolic pressure during the hemodialysis. All parameters were evaluated for the possible predisposing factors under each definition.A total of 24 IDH-f and 37 IDH-n were noted in 177 visits. For both definitions, central pulse pressure seemed to be a consistent predisposing factor. Furthermore, lower sympathetic activity (odds ratio [OR] 0.55; 95% confidence interval [CI] 0.35-0.87), lower pulse pressure (OR 0.95; 95% CI 0.92-0.98), and higher augmentation index (OR 17.36; 95% CI 1.48-204.10) were the possible predisposing factors for IDH-f. On the contrary, lower mean arterial pressure (OR 0.87; 95% CI 0.78-0.98) was identified as the possible factor for IDH-n.It was suggested that the lower central pulse pressure and sympathetic activity might be involved in the development of IDH.


Assuntos
Hemodinâmica/fisiologia , Hipotensão/etiologia , Hipotensão/fisiopatologia , Falência Renal Crônica/terapia , Diálise Renal/efeitos adversos , Adulto , Idoso , Idoso de 80 Anos ou mais , Pressão Sanguínea/fisiologia , Estudos de Casos e Controles , Frequência Cardíaca , Humanos , Pessoa de Meia-Idade , Análise de Onda de Pulso
5.
Comput Methods Biomech Biomed Engin ; 24(11): 1206-1211, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33410708

RESUMO

Sufficient interfragmental movement is the key to successful fracture healing in the theory of secondary bone healing. The far-cortical locking technique enables both stiffness reduction and parallel motion for ideal callus formation and fracture healing, but the influence of plate-bone gap on the performance of far-cortical locking technique remains unclear. The current study conducted a series of finite element analyses with mechanical validation to clarify this issue. Plate-bone gaps were assigned by 1, 2, 3, and 4 mm in a simulated mid-shaft fracture model fixed with locking plate and six semi-rigid locking screws. Axial compressive load to 500 N was applied to the fixation structure to evaluate the structural stiffness, pattern of interfragmental movement (parallel motion), and stresses on the screws. Results revealed the increased plate-bone gaps reduced the structural in order (315.3, 288.8, 264.9, and 243.4 N/mm). Tilting angles for determining parallel interfragmental movement (1.58°-1.85°) and stresses on semi-rigid screws for evaluating implant safety were not severely altered. Greater stresses were found on the screws adjacent to the fracture site in all simulated models. The current study suggested that 1 mm gap between the locking plate and the bone shall be ideal in view of parallel motion achieved balanced callus formation in far-cortical locking technique. Issue of reducing structural stiffness with limited plate-bone gap distance should be further investigated.


Assuntos
Parafusos Ósseos , Fixação Interna de Fraturas , Fenômenos Biomecânicos , Placas Ósseas , Análise de Elementos Finitos , Consolidação da Fratura
6.
J Med Biol Eng ; 38(5): 835-844, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30220902

RESUMO

The aim of this study was to establish a web-based platform for exchanging medical device management and maintenance experiences to enhance the professional competency of clinical engineers (CEs), which ensures the quality of medical devices and increases patients' satisfaction with medical services. Medical devices play an essential role in diagnosis and disease management. CEs are responsible for providing functional medical devices that contribute worthwhile functions to a medical service to improve patients' health and safety. The purpose of the platform is to facilitate collection and sharing of medical device incidents experiences to improve CEs' capability. To provide useful and practical information for CEs, an event review committee, composed of experts with more than 20 years of clinical engineering experience who were recruited as reviewers, was established under the platform. Cases submitted to the platform were required to have comprehensive descriptions of the device and events. Each case was evaluated by at least two reviewers based on five evaluation indices: (1) severity, (2) breadth, (3) frequency, (4) insidiousness, and (5) correctness. After being reviewed, each final report was published on the platform to be shared with the event submitters and other members. The results show that 116 staffs from 32 different hospitals, registered to join this platform. From January 2015 to December 2016, 70 events were submitted with 56 reports. This study also assessed the platform's benefits for CEs. A total of 93 respondents completed a questionnaire survey: 93% of the CEs agreed that the information from the platform helped them do their job. The web-based platform has high value as an experience-sharing interface for medical devices. The CEs obtained extremely useful information from the platform for medical device management and their daily duties. This study provided an online training model with systematic methods to improve the quality and effectiveness of medical device management.

7.
Med Eng Phys ; 56: 48-53, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29685856

RESUMO

The far cortical locking (FCL) system, a novel bridge-plating technique, aims to deliver controlled and symmetric interfragmentary motion for a potential uniform callus distribution. However, clinical data for the practical use of this system are limited. The current study investigated the biomechanical effect of a locking plate/far cortical locking construct on a simulated comminuted diaphyseal fracture of the synthetic bones at different distance between the plate and the bone. Biomechanical in vitro experiments were performed using composite sawbones as bone models. A 10-mm osteotomy gap was created and bridged with FCL constructs to determine the construct stiffness, strength, and interfragmentary movement under axial compression, which comprised one of three methods: locking plates applied flush to bone, at 2 mm, or at 4 mm from the bone. The plate applied flush to the bone exhibited higher stiffness than those at 2 mm and 4 mm plate elevation. A homogeneous interfragmentary motion at the near and far cortices was observed for the plate at 2 mm, whereas a relatively large movement was observed at the far cortex for the plate applied at 4 mm. A plate-to-bone distance of 2 mm had the advantages of reducing axial stiffness and providing nearly parallel interfragmentary motion. The plate flush to the bone prohibits the dynamic function of the far cortical locking mechanism, and the 4-mm offset was too unstable for fracture healing.


Assuntos
Placas Ósseas , Fixação Interna de Fraturas/instrumentação , Parafusos Ósseos , Diáfises/lesões , Diáfises/cirurgia , Humanos
8.
J Orthop Surg (Hong Kong) ; 26(1): 2309499018760130, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29486668

RESUMO

Headless compression screws (HCSs) are commonly used to fixate small bones and articular fractures. Understanding the biomechanical efficacy of different HCS designs can help surgeons make proper interfragmentary compression when a specific implant is chosen. HCSs with three different central shaft designs (unthreaded, fully threaded, and partially threaded) were studied: the Herbert-Whipple, Mini-Acutrak 2, and headless reduction (HLR). Polyurethane foam blocks were machined with a simulated fracture gap of 0.5 mm and set onto a custom-made jig to simultaneously measure compression force and driving torque during screw insertion. The maximal achievable compression forces and driving torques recorded were 47.4 ± 0.9 N and 145.11 ± 1.65 N mm for the HLR, 50.98 ± 1.29 N and 152.62 ± 2.83 N mm for the Mini-Acutrak 2, and 19.33 ± 1.0 N and 33.4 ± 2.2 N mm for the Herbert-Whipple. Overall, the compression force of the Mini-Acutrak 2 and HLR increased with the torque. Unlike the other screws, the Herbert-Whipple's driving torque increased while the compression force decreased after peak compression force was achieved. The partially threaded shaft design (HLR) demonstrated equivalent biomechanical advantage with the Mini-Acutrak 2 in interfragmentary compression. The HCSs with cone-shaped proximal ends (HLR and Mini-Acutrak 2) maintained their compression force during over-fastening, whereas the unthreaded central shaft of the Herbert-Whipple screw caused it to lose compression force.


Assuntos
Parafusos Ósseos , Simulação por Computador , Fixação Interna de Fraturas/métodos , Fraturas Ósseas/cirurgia , Fraturas Intra-Articulares/cirurgia , Fenômenos Biomecânicos , Humanos , Poliuretanos , Pressão
9.
J Foot Ankle Surg ; 56(6): 1165-1169, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28888405

RESUMO

Calcaneal fracture can lead to long-term disability and have a considerable economic effect. Most calcaneal fractures are intraarticular fractures involving the posterior facet of the subtalar joint. Treating displaced intraarticular calcaneal fractures is complicated because of the lack of an optimal treatment option. Internal fixation typically involves screw-and-plate implants, which can be unfavorable owing to the lack of an anatomic design and the intraoperative bending required for the plate to contour to the irregular surface of the calcaneus. We assessed the outcomes of 30 patients treated using innovative, anatomically designed calcaneal locking plates and the perceived advantages for surgeons. Postoperative computed tomography images of the affected feet were obtained, and the functional performance was recorded. The mean average Böhler angle had increased significantly from 16.8° ± 14.9° to 28.5° ± 9.4° (p < .001). The mean average maximal fracture gap and maximal step-off in the posterior facet of the subtalar joint in the coronal computed tomography images also decreased significantly from 2.8 ± 3.7 mm to 0.8 ± 1.3 mm (p < .01) and from 3.3 ± 2.8 mm to 0.8 ± 1.2 mm (p < .001), respectively. The mean average American Orthopaedic Foot and Ankle Ankle-Hindfoot scale score was 93.9 ± 7.1 at the final follow-up visit. In addition, the surgical time was reduced because bending the plate was not required and the quality of reduction could be assessed easily by examining the gap between the cortex and the plate. The results were promising, revealing that the anatomic locking plate can be used effectively in the treatment of displaced intraarticular calcaneal fractures using simple reduction techniques with a potentially shortened operating time.


Assuntos
Placas Ósseas , Calcâneo/lesões , Traumatismos do Pé/cirurgia , Fixação Interna de Fraturas/métodos , Fraturas Intra-Articulares/cirurgia , Adulto , Calcâneo/cirurgia , Desenho de Equipamento , Feminino , Traumatismos do Pé/diagnóstico por imagem , Fixação Interna de Fraturas/instrumentação , Humanos , Fraturas Intra-Articulares/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Radiografia , Adulto Jovem
10.
Comput Math Methods Med ; 2017: 2750701, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28634497

RESUMO

Inspiratory flow limitation (IFL) is a critical symptom of sleep breathing disorders. A characteristic flattened flow-time curve indicates the presence of highest resistance flow limitation. This study involved investigating a real-time algorithm for detecting IFL during sleep. Three categories of inspiratory flow shape were collected from previous studies for use as a development set. Of these, 16 cases were labeled as non-IFL and 78 as IFL which were further categorized into minor level (20 cases) and severe level (58 cases) of obstruction. In this study, algorithms using polynomial functions were proposed for extracting the features of IFL. Methods using first- to third-order polynomial approximations were applied to calculate the fitting curve to obtain the mean absolute error. The proposed algorithm is described by the weighted third-order (w.3rd-order) polynomial function. For validation, a total of 1,093 inspiratory breaths were acquired as a test set. The accuracy levels of the classifications produced by the presented feature detection methods were analyzed, and the performance levels were compared using a misclassification cobweb. According to the results, the algorithm using the w.3rd-order polynomial approximation achieved an accuracy of 94.14% for IFL classification. We concluded that this algorithm achieved effective automatic IFL detection during sleep.


Assuntos
Algoritmos , Técnicas de Diagnóstico do Sistema Respiratório , Síndromes da Apneia do Sono/diagnóstico , Humanos , Respiração
11.
Biomed Res Int ; 2017: 8149109, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28497066

RESUMO

The clavicle has a complex geometry that makes plate fixation technically difficult. The current study aims to measure the anatomical parameters of Chinese clavicles as reference for plate design. One hundred clavicles were analyzed. The clavicle bone model was reconstructed by using computed tomography images. The length, diameters, and curvatures of the clavicle were then measured. The female clavicle was shorter, more slender, and less curved in lateral part than the male clavicle. There was a positive relationship between height and clavicle parameters except lateral curve and depth. The measurements of Chinese clavicles were generally smaller than Caucasians. The clavicle curves were correlated with the bone length; thus consideration of the curve variations may be necessary as designing size distribution of clavicle plate.


Assuntos
Clavícula/anatomia & histologia , Clavícula/diagnóstico por imagem , Caracteres Sexuais , Tomografia Computadorizada por Raios X , Adulto , Povo Asiático , China , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
12.
Biomed Tech (Berl) ; 62(3): 257-261, 2017 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-27341556

RESUMO

Headless compression screws (HCSs) are commonly utilized devices for small bone fracture fixation. The Mini-Acutrak 2 and headless reduction (HLR) screws are the newer version types, in which both have fully threaded and variable pitch design. Specifically, the HLR is characterized by two thread runouts to facilitate implantation. With the thread runouts, the holding strength of the screw may be compromised. To the best of our knowledge, no study has examined the pullout force of the global sizes of a HCS. We sought to determine the pullout strength of the HLR and compare the strength of this screw with that of the Mini-Acutrak 2. Synthetic bone blocks with simulated transverse fractures were used to conduct the tests. Four commonly used sizes of the HLR were examined, and one Mini-Acutrak 2 was employed for comparison. Five screws of each size were tested. The pullout force of all screws that were tested in this study ranged from 45.23 to 233.22 N. The results revealed that the pullout force increased as the screw diameter increased. Interestingly, we found that one small screw outperformed the Mini-Acutrak 2, which has a larger diameter. This study provided extensive knowledge regarding the pullout strength of fully threaded HCSs of different sizes. An unexpected finding is that a small screw has higher holding power than a large one because of its increased number of threads. Therefore, we suggest that the thread number should be a critical consideration for the design of size distribution of HCSs.


Assuntos
Parafusos Ósseos/normas , Fixação Interna de Fraturas/instrumentação , Pressão , Resistência à Tração/fisiologia , Desenho de Equipamento , Humanos
13.
Med Biol Eng Comput ; 55(8): 1189-1198, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27744563

RESUMO

Exercise periodic breathing (EPB) is associated with exercise intolerance and poor prognosis in patients with heart failure (HF). However, EPB detection during cardiopulmonary exercise test (CPET) is difficult. The present study investigated the use of a wireless monitoring device to record the EPB during CPET and proposed quantization parameter estimates for the EPB. A total of 445 patients with HF were enrolled and underwent exercise tests. The ventilation data from the wearable device were compared with the data obtained during the CPET and were analyzed based on professional opinion and on 2 automated programs (decision tree [DT] and oscillatory pattern methods). The measurement accuracy was greater with the DT method (89 %) than with the oscillatory pattern method (75 %). The cutoffs for EPB recognition using the DT method were (1) an intercept of the regression line passing through the minute ventilation rate vs. the time curve during the recovery phase ≥64.63, and (2) an oscillatory phase duration to total exercise time ratio ≥0.5828. The wearable device was suitable for the assessment of EPB in patients with HF, and our new automated analysis system using the DT method effectively identified the EPB pattern.


Assuntos
Testes Respiratórios/instrumentação , Respiração de Cheyne-Stokes/diagnóstico , Respiração de Cheyne-Stokes/fisiopatologia , Teste de Esforço/instrumentação , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/fisiopatologia , Termografia/instrumentação , Respiração de Cheyne-Stokes/etiologia , Diagnóstico por Computador/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Feminino , Insuficiência Cardíaca/complicações , Humanos , Masculino , Pessoa de Meia-Idade , Oscilometria/instrumentação , Reprodutibilidade dos Testes , Mecânica Respiratória , Reologia/instrumentação , Sensibilidade e Especificidade
14.
Med Eng Phys ; 38(10): 1070-5, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27423702

RESUMO

Open reduction internal fixation technique has been generally accepted for treatment of midshaft clavicle fractures. Both superior and anterior clavicle plates have been reported in clinical or biomechanical researches, while presently the spiral clavicle plate design has been introduced improved biomechanical behavior over conventional designs. In order to objectively realize the multi-directional biomechanical performances among the three geometries for clavicle plate designs, a current conceptual finite element study has been conducted with identical cross-sectional features for clavicle plates. The conceptual superior, anterior, and spiral clavicle plate models were constructed for virtual reduction and fixation to an OTA 15-B1.3 midshaft transverse fracture of clavicle. Mechanical load cases including cantilever bending, axial compression, inferior bending, and axial torsion have been applied for confirming the multi-directional structural stability and implant safety in biomechanical perspective. Results revealed that the anterior clavicle plate model represented lowest plate stress under all loading cases. The superior clavicle plate model showed greater axial compressive stiffness, while the anterior clavicle plate model performed greater rigidity under cantilever bending load. Three model represented similar structural stiffness under axial torsion. Played as a transition structure between superior and anterior clavicle plate, the spiral clavicle plate model revealed comparable results with acceptable multi-directional biomechanical behavior. The concept of spiral clavicle plate design is worth considering in practical application in clinics. Implant safety should be further investigated by evidences in future mechanical tests and clinical observations.


Assuntos
Clavícula/lesões , Análise de Elementos Finitos , Fraturas Ósseas , Fenômenos Mecânicos , Idoso , Fenômenos Biomecânicos , Placas Ósseas , Parafusos Ósseos , Clavícula/diagnóstico por imagem , Clavícula/cirurgia , Humanos , Masculino , Tomografia Computadorizada por Raios X
15.
Injury ; 47(6): 1191-5, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26975793

RESUMO

BACKGROUND: Locking plate fixation for proximal humeral fractures is a commonly used device. Recently, plate breakages were continuously reported that the implants all have a mixture of holes allowing placement of both locking and non-locking screws (so-called combi plates). In commercialized proximal humeral plates, there still are two screw hole styles included "locking and dynamic holes separated" and "locking hole only" configurations. It is important to understand the biomechanical effect of different screw hole style on the stress distribution in bone plate. METHODS: Finite element method was employed to conduct a computational investigation. Three proximal humeral plate models with different screw hole configurations were reconstructed depended upon an identical commercialized implant. A three-dimensional model of a humerus was created using process of thresholding based on the grayscale values of the CT scanning of an intact humerus. A "virtual" subcapital osteotomy was performed. Simulations were performed under an increasing axial load. The von Mises stresses around the screw holes of the plate shaft, the construct stiffness and the directional displacement within the fracture gap were calculated for comparison. RESULTS: The mean value of the peak von Mises stresses around the screw holes in the plate shaft was the highest for combi hole design while it was smallest for the locking and dynamic holes separated design. The stiffness of the plate-bone construct was 15% higher in the locking screw only design (132.6N/mm) compared with the combi design (115.0N/mm), and it was 4% higher than the combi design for the locking and dynamic holes separated design (119.5N/mm). The displacement within the fracture gap was greatest in the combi hole design, whereas it was smallest for the locking hole only design. CONCLUSIONS: The computed results provide a possible explanation for the breakages of combi plates revealed in clinical reports. The locking and dynamic holes separated design may be a better configuration to reduce the risk of plate fracture.


Assuntos
Fixação Interna de Fraturas/métodos , Úmero/cirurgia , Imageamento Tridimensional , Teste de Materiais/métodos , Fraturas do Ombro/cirurgia , Fenômenos Biomecânicos , Placas Ósseas , Parafusos Ósseos , Análise de Elementos Finitos , Fixação Interna de Fraturas/instrumentação , Humanos , Úmero/anatomia & histologia , Masculino , Pessoa de Meia-Idade , Fraturas do Ombro/diagnóstico por imagem , Fraturas do Ombro/patologia , Estresse Mecânico , Tomografia Computadorizada por Raios X
16.
Comput Methods Biomech Biomed Engin ; 19(13): 1363-70, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26813403

RESUMO

Initial stability is essential for open reduction internal fixation of intraarticular calcaneal fractures. Geometrical feature of a calcaneal plate is influential to its endurance under physiological load. It is unclear if conventional and pre-contoured anatomical calcaneal plates may exhibit differently in biomechanical perspective. A Sanders' Type II-B intraarticular calcaneal fracture model was reconstructed to evaluate the effectiveness of calcaneal plates using finite element methods. Incremental vertical joint loads up to 450 N were exerted on the subtalar joint to evaluate the stability and safety of the calcaneal plates and bony structure. Results revealed that the anatomical calcaneal plate model had greater average structural stiffness (585.7 N/mm) and lower von Mises stress on the plate (774.5 MPa) compared to those observed in the conventional calcaneal plate model (stiffness: 430.9 N/mm; stress on plate: 867.1 MPa). Although both maximal compressive and maximal tensile stress and strain were lower in the anatomical calcaneal plate group, greater loads on fixation screws were found (average 172.7 MPa compared to 82.18 MPa in the conventional calcaneal plate). It was noted that high magnitude stress concentrations would occur where the bone plate bridges the fracture line on the lateral side of the calcaneus bone. Sufficient fixation strength at the posterolateral calcaneus bone is important for maintaining subtalar joint load after reduction and fixation of a Sanders' Type II-B calcaneal fracture. In addition, geometrical design of a calcaneal plate should worth considering for the mechanical safety in practical usage.


Assuntos
Placas Ósseas , Calcâneo/fisiopatologia , Análise de Elementos Finitos , Fraturas Ósseas/patologia , Fraturas Ósseas/fisiopatologia , Articulações/patologia , Articulações/fisiopatologia , Idoso , Fenômenos Biomecânicos , Parafusos Ósseos , Força Compressiva , Fraturas Ósseas/cirurgia , Humanos , Masculino , Modelos Anatômicos , Estresse Mecânico , Resistência à Tração
17.
Biomed Tech (Berl) ; 61(3): 331-6, 2016 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-26351785

RESUMO

Medial migration or cutout of the neck helical blade has commonly occurred in the treatment of trochanteric fracture of the femur. The position of the helical blade within the femoral head is one of the influencing factors that cause the blade to perforate the intact joint surface; however, the ideal placement of the helical blade is not currently known. A finite element model of a femur/nail construct was utilized to analyze five possible blade positions in the femoral head. Normal strain at the fracture surface, the minimum principal strain in the cancellous bone, and the von Mises stress in the implant itself were calculated and compared between different blade positions. The results showed that a large area of normal compressive strain at the fracture surface was observed in the inferior and posterior blade positions. The volume of cancellous bone strained to yielding in the femoral head and neck was lower for the inferior and posterior positions, whereas it was the highest for the superior position. The inferior and posterior positions had lower von Mises stress in the implant itself. The inferior and posterior positions may be the ideal position for the intramedullary nail with a helical neck blade.


Assuntos
Osso Esponjoso/fisiologia , Cabeça do Fêmur/fisiologia , Colo do Fêmur/fisiologia , Análise de Elementos Finitos/normas , Fixação Interna de Fraturas , Humanos , Desenho de Prótese
18.
Oncotarget ; 6(11): 8663-75, 2015 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-25796627

RESUMO

Cancer stem cells (CSCs) are usually tolerant to chemotherapy and radiotherapy and associated with tumor relapse. Suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor (HDACI), is currently being used in clinical trials of lung cancer. However, SAHA facilitates the formation of induced pluripotent stem cells from somatic cells. We hypothesized that SAHA would mediate the CSCs properties and subsequently confer a more malignant phenotype in lung cancer. Transfected H1299 lung cancer cells, which stably expresses a triple fused reporter gene (DsRedm-Fluc-tTKsr39) under the control of CMV promoter was used to establish a xenograft mouse model. After the treatment of SAHA, H1299 cell line and tumor xenografts were sorted by fluorescence-activated cell sorting (FACS) based on aldehyde dehydrogenase (ALDH) activity. We found that SAHA could suppress the growth of xenografted H1299 tumors with decreased proportion of ALDHbr lung cancer cells indicating that SAHA may target CSCs. However, SAHA significantly enhanced the tumor initiating capacity and the expression of malignant genes such as KCNMA1, MORF4L2 and ASPM in the remaining living ALDHbr cells. These findings suggested that SAHA treatment created a more drug-resistant state in residual ALDHbr cells. The in vivo imaging technique may facilitate searching and characterization of CSCs.


Assuntos
Adenocarcinoma/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Inibidores de Histona Desacetilases/farmacologia , Ácidos Hidroxâmicos/farmacologia , Subunidades alfa do Canal de Potássio Ativado por Cálcio de Condutância Alta/biossíntese , Neoplasias Pulmonares/tratamento farmacológico , Proteínas de Neoplasias/biossíntese , Proteínas do Tecido Nervoso/biossíntese , Fatores de Transcrição/biossíntese , Adenocarcinoma/metabolismo , Adenocarcinoma/patologia , Aldeído Desidrogenase/análise , Animais , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/patologia , Autorrenovação Celular/efeitos dos fármacos , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Citometria de Fluxo , Genes Reporter , Xenoenxertos , Inibidores de Histona Desacetilases/uso terapêutico , Humanos , Ácidos Hidroxâmicos/uso terapêutico , Subunidades alfa do Canal de Potássio Ativado por Cálcio de Condutância Alta/genética , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Proteínas de Neoplasias/genética , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/enzimologia , Proteínas do Tecido Nervoso/genética , Fatores de Transcrição/genética , Transfecção , Vorinostat
19.
J Xray Sci Technol ; 23(1): 25-31, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25567404

RESUMO

PURPOSE: Segmentation of the left ventricle (LV) in cardiac CT (CCT) images is difficult due to the intensity heterogeneity arising from accumulation of contrast agent in papillary muscle and trabeculae carneae. In this study, we demonstrated the random walks method for LV segmentation in CCT through cardiac phases. METHODS: 63 CCT data sets from 7 patients with 9 cardiac phases were included in this study. All cardiac CT examinations were performed with GE 64-detector CT scanner with ECG gating. In each patient, 60-80 ml iohexol was injected at a flow rate of 5 ml/sec followed by 60 ml normal saline solution. Random walks (RW) based on probability of labels was used for LV segmentation. The LV delineations generated by the experienced physician (MD), conventional image-based method (IB), and RW were compared. RESULTS: In general the contours segment the LV closely by RW and MD, but the discrepancies in papillary muscle and trabeculae carneae were observed while using the IB method. CONCLUSION: We showed the RW method potentially improved LV segmentation as compared to the volume by conventional IB method. In this study, we demonstrated the clinical feasibility of LV volume segmentation using random walks algorithm.


Assuntos
Interpretação Estatística de Dados , Ventrículos do Coração/diagnóstico por imagem , Reconhecimento Automatizado de Padrão/métodos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Tomografia Computadorizada por Raios X/métodos , Disfunção Ventricular Esquerda/diagnóstico por imagem , Algoritmos , Simulação por Computador , Humanos , Modelos Estatísticos , Intensificação de Imagem Radiográfica/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
20.
ScientificWorldJournal ; 2014: 106941, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25530989

RESUMO

Adequately shaped femoral plate is critical for the fixation of fracture in the pertrochanteric regions. Lateral aspect of greater trochanter is an important region where the proximal femoral plate anchored. However, little is known regarding the morphology of greater trochanter. The objective of this study was to measure main dimensions of greater trochanter and other regions in the proximal end of the femur to provide an anatomical basis for the design of the proximal femoral plate. Anthropometric data on the proximal femur were performed utilizing three-dimensional computational modeling. Computed tomography images of healthy femurs in 53 women and 47 men were contributed to three-dimensional femur modeling. All data were compared between male and female femora. The results showed that mean values for male group were found to be greater in most of measured femoral dimensions. Oppositely, females demonstrated higher neck-shaft angle on anteroposterior view and femoral anteversion angle. The anthropometric data can be used for the anatomical shape design of femoral plates for osteosynthesis of fractures in the trochanteric regions. A distinct plate design may be necessary to accommodate differences between the genders.


Assuntos
Povo Asiático , Placas Ósseas , Fêmur/anatomia & histologia , Desenho de Prótese , Adulto , China , Feminino , Fêmur/diagnóstico por imagem , Humanos , Masculino , Tomografia Computadorizada por Raios X
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