Biomechanical analysis of narrow dental implants for maxillary anterior rehabilitation / Análise biomecânica de implantes de diâmetro reduzido para reabilitação da região anterior da maxila

Introdução: O conhecimento da biomecânica de implantes de diâmetro reduzido indica dimensões seguras para uso clínico. Objetivo: O objetivo do presente estudo foi comparar biomecanicamente implantes de diâmetro regular e reduzido para suporte de próteses implantossuportadas unitárias na região anterior da maxila por meio de análise de elementos finitos 3D (3D-FEA). Material e método: Quatro modelos 3D-FEA foram desenvolvidos a partir de recomposição de tomografia computadorizada e dados da literatura: um bloco ósseo na região incisiva lateral superior direita com implante e coroa. M1: 3,75 x 13 mm, M2: 3,75 x 8,5 mm, M3: 2,9 x 13 mm e M4: 2,9 x 8,5 mm. Foi aplicada carga de 178 N nos ângulos 0, 30 e 60 graus em relação ao longo eixo do implante. Foram avaliados mapas de tensão de Von Mises, tensão principal máxima e microdeformação. Resultado: M3 e M4 apresentaram maiores valores de tensão e microdeformação que M1 e M2, principalmente quando foram aplicadas forças inclinadas. Porém, M3 apresentou comportamento biomecânico melhor do que M4. Conclusão: Pode-se concluir que reduzir o diâmetro dos implantes pode prejudicar a biomecânica durante a aplicação de forças, mas a distribuição e intensidade das tensões, bem como os valores de microdeformação podem ser melhorados se o comprimento do implante for aumentado

Introduction: Narrow diameter implants biomechanics knowledge indicates safe dimensions for clinical use. Objective: Purpose of the present study was biomechanically to compare regular and narrow diameter implants to support single implant-supported prosthesis in the anterior region of the maxilla by 3D finite element analysis (3D-FEA). Material and method: Four 3D-FEA models were developed form CT scan recompositing and literature data: a bone block in the right upper lateral incisive region with implant and crown. M1: 3.75 x 13 mm, M2: 3.75 x 8.5 mm, M3: 2.9 x 13 mm and M4: 2.9 x 8.5 mm. It was applied load was of 178 N at 0, 30 and 60 degrees in relation to implant long axis. Von Mises stress, maximum principal stress and microdeformation maps were evaluated. Result: M3 and M4 did show higher tension and higher microdeformation values than M1 and M2, especially when inclined forces were applied. However, M3 presented enhanced biomechanical behavior than M4. Conclusion: It can be concluded that reduce the diameter of the implants can disadvantage to the biomechanics during the application of forces, but the distribution and intensity of the stresses, as well as the micro deformation values can be improved if the length of the implant is increased

Cortisol Reactivity to a physical stressor in Patients with Depression and Alzheimer's disease.

Some prevalent mental disorders in the elderly, such as Alzheimer's disease (AD) and major depression disorder (MDD), are associated with chronic stress and consequently with possible dysregulation of hypothalamic-pituitary-adrenal (HPA) axis and cortisol levels in basal conditions or in the reactivity of an acute stressor. However, evidence of cortisol behavior after a physical stressor in patients with AD and MDD is scarce. Objective: This study aimed to investigate the cortisol reactivity to a single session of physical exercise in patients with MDD and AD and compare it to healthy control (HC) older individuals. Methods: HC individuals (n=10) and elderly with clinical diagnostic of MDD (n=08) and AD (n=13) were submitted to a single bout of aerobic exercise in a treadmill during 30 minutes of moderate intensity. Salivary cortisol was collected before and after acute stressor. A repeated-measure analysis of variance (ANOVA), spearman correlation, and linear regression were performed. Results: The repeated-measure ANOVA revealed no interaction for cortisol on the moment×group [F(2.000, 28.000)=1.285; p=0.293] and no effect for group (F=0.323; p=0.727). However, a significant effect for moment [F(1.000, 28.000)=4.930; p=0.035] was found, with a decreased cortisol levels in postexercise for all groups. The effect size (ES) of cortisol reduction was small for patients with MDD (d=0.402) and trivial for patients with AD (d=0.166) and HC group (d=0.090). Conclusions: All participants show a decreased cortisol reactivity to a physical stressor, which can be associated with an impairment in coping with an acute stressor.

A doença de Alzheimer (DA) e o transtorno depressivo maior (TDM) são transtornos que acometem idosos e estão associadas ao estresse crônico e à desregulação do eixo hipotálamo-hipófise-adrenal (HPA), que repercute em alterações nos níveis de cortisol (basal e reatividade). Objetivo: Investigar a reatividade do cortisol em uma única sessão de exercício físico em pacientes com TDM e com DA e compará-la com a de idosos saudáveis. Métodos: Indivíduos controle saudáveis (n=10) e idosos com diagnóstico clínico de TDM (n=08) e DA (n=13) foram submetidos a uma única sessão de exercício aeróbio em esteira rolante, durante 30 minutos, em intensidade moderada. O cortisol salivar foi coletado antes e depois do estressor agudo. Na estatística, foram realizadas as análises de variância (ANOVA) de medidas repetidas, correlação de spearman e regressão linear. Resultados: Não foi encontrada interação para momento x grupo [F (2.000, 28.000)=1.285; p=0,293] e tampouco efeito para o grupo (F=0,323; p=0,727). Todavia, foi observado efeito significativo para o momento [F(1,000, 28,000)=4,930; p=0,035], mostrando diminuição dos níveis de cortisol no pós-exercício para todos os grupos. O tamanho do efeito (TE) foi considerado pequeno para o grupo TDM (d=0,402) e trivial para o DA (d=0,166) e o saudável (d=0,090). Conclusões: Todos os participantes apresentaram diminuição da reatividade do cortisol a um estressor físico, o que pode estar associado a um comprometimento no enfrentamento de um estressor agudo.

Comparison of the High Cycle Fatigue Behavior of the Orthodontic NiTi Wires: An in Vitro Study

Abstract Objective: To compare the high-cycle fatigue behavior of four commercially available NiTi orthodontic wires. Material and Methods: Twelve NiTi orthodontic wires, round, 0.016-in, three per brand, were selected and divided into four groups: G1 - Heat-activated NiTi, G2 - Superelastic NiTi, G3 - Therma-Ti, and G4 - CopperNiTi. The atomic absorption spectrometry method was used to determine the chemical composition of investigated NiTi wires. We also performed a fatigue test at three-point bending using a universal testing machine for 1000 cycles in a 35 °C water bath. For the first and thousandth cycle, the average plateau load and the plateau length were determined in the unloading area of the force versus displacement diagram. In addition, we calculated the difference between the average plateau load of the first and thousandth cycle (∆F), as well as the difference between the plateau length of both cases (∆L). Results: According to our results, there were no significant differences between the average plateau load of the first and thousandth cycles of each group (p>0.05) and in the plateau length of the first and thousandth cycles of the groups (p>0.05). Conclusion: There were no significant differences between the groups changing the superelasticity property after high-cycle fatigue.

Effect of thickness on shrinkage stress and bottom-to-top hardness ratio of conventional and bulk-fill composites.

This study evaluated the effect of the material thickness on shrinkage stress and bottom-to-top hardness ratio of conventional and bulk-fill composites. Six commercial composites were selected based on their different technologies: Two conventional (C1, C2), two high-viscosity bulk-fill (HVB1, HVB2), and two low-viscosity bulk-fill (LVB1, LVB2). Shrinkage stress was analyzed for five specimens with 2 mm thickness (C-factor 0.75 and volume 24 mm3 ) and five specimens with 4 mm thickness (C-factor 0.375 and volume 48 mm3 ) for 300 s in a universal testing machine. Bottom-to-top hardness ratio values were obtained from Knoop microhardness measurements in specimens with 2- and 4-mm thickness (n = 5). Thickness increase resulted in significantly higher shrinkage stress for all materials with the exception of HVB2 and LVB1. C1, C2, HVB2, and LVB1 showed lower bottom-to-top hardness ratios at 4 mm than at 2 mm. Only LVB2 presented a bottom-to-top hardness ratio lower than 80% at 2 mm, while HVB1 surpassed this threshold at 4 mm of depth. The results suggest that the increase of composite thickness affected the shrinkage stress values. Also, thickness increase resulted in lower bottom-to-top hardness ratio. HVB1 showed better behavior than other bulk-fill materials, with low stress and adequate bottom-to-top hardness ratio at 4 mm thickness.

A case report of individualized ventilation in a COVID-19 patient - new possibilities and caveats to consider with flow-controlled ventilation.

BACKGROUND: Flow-controlled ventilation (FCV) is a novel ventilation method increasingly being used clinically, particularly during the current COVID-19 pandemic. However, the continuous flow pattern in FCV during inspiration and expiration has a significant impact on respiratory parameters and ventilatory settings compared to conventional ventilation modes. In addition, the constant flow combined with direct intratracheal pressure measurement allows determination of dynamic compliance and ventilation settings can be adjusted accordingly, reflecting a personalized ventilation approach. CASE PRESENTATION: A 50-year old women with confirmed SARS-CoV-2 infection suffering from acute respiratory distress syndrome (ARDS) was admitted to a tertiary medical center. Initial ventilation occurred with best standard of care pressure-controlled ventilation (PCV) and was then switched to FCV, by adopting PCV ventilator settings. This led to an increase in oxygenation by 30 %. Subsequently, to reduce invasiveness of mechanical ventilation, FCV was individualized by dynamic compliance guided adjustment of both, positive end-expiratory pressure and peak pressure; this intervention reduced driving pressure from 18 to 12 cm H2O. However, after several hours, compliance further deteriorated which resulted in a tidal volume of only 4.7 ml/kg. CONCLUSIONS: An individualized FCV approach increased oxygenation parameters in a patient suffering from severe COVID-19 related ARDS. Direct intratracheal pressure measurements allow for determination of dynamic compliance and thus optimization of ventilator settings, thereby reducing applied and dissipated energy. However, although desirable, this personalized ventilation strategy may reach its limits when lung function is so severely impaired that patient's oxygenation has to be ensured at the expense of lung protective ventilation concepts.

Microhardness and Diametral Compression Strength of Single Fill Composite

ABSTRACT: To evaluate Knoop microhardness and diametral compression strength at different polymerization times. A total of 80 cylindrical samples with Filtek resin™ One Bulk Fill were made to perform the in vitro study, using half of total samples (n=40) for each test and divided equally between groups (n=10). All samples were made according to ISO 4049 using 2 mm thickness Teflon matrix and a central orifice with 4 mm diameter. Four different times of light-curing in Standard mode suggested by the light-unit manufacturer were selected, therefore, group 1 samples (G1) were light-cured for 5 seconds; group 2 (G2) for 10 seconds; group 3 (G3) for 15 seconds, and group 4 (G4) for 20 seconds. A radiant display, which means a power in mW/cm2 by time in seconds was expressed in Joules (J). The samples were stored in a dark container with distilled water at a temperature of 37°C for 48 hours before testing. One-way analysis of variance (ANOVA) with T-Test (LSD) of multiple comparisons of the mean values of Knoop hardness and diametral compression strength was performed, with significance index α=0.05. Regarding the Knoop microhardness test, G1 (35.73 ± 6.2) presented the lowest values, followed by G2, while G3 and G4 did not present statistical differences between them. For the diametral compression test, G1 (1387.76 ± 190.51) obtained the lowest value when compared to the other groups. G2, G3, and G4 did not present significant statistical differences. The different polymerization times influenced the Knoop microhardness and the diametral compression strength of Bulk Fill resin.

RESUMEN: El objetivo de este trabajo fue evaluar la microdureza Knoop y la resistencia a la compresión diametral en diferentes tiempos de polimerización. En el estudio realizado in vitro, se analizó un total de 80 muestras cilíndricas con la resina Filtek™ One Bulk Fill, utilizando la mitad (n=40) para cada prueba realizada y dividida en partes iguales entre los grupos (n=10). Todas las muestras se tomaron de acuerdo con ISO 4049 utilizando matrices de teflón de 2 mm de espesor y orificio central con 4 mm de diámetro. Se seleccionó cuatro veces el fotocurado de manera estándar, sugerido por el fabricante. Por lo tanto, las muestras del grupo 1 (G1) se fotopolimerizaron durante 5 segundos; grupo 2 (G2) durante 10 segundos; grupo 3 (G3) durante 15 segundos y grupo 4 (G4) durante 20 segundos. La exposición radiante, que indica la potencia en mW / cm2 a lo largo del tiempo en segundos, se expresó en julios (J). Las muestras se almacenaron en un recipiente oscuro con agua destilada en una estufa a una temperatura de 37°C durante 48 horas antes del ensayo. Se realizó para comparaciones múltiples de los valores medios, análisis de varianza (ANOVA) de un criterio con la prueba T (LSD) tanto de la dureza de Knoop como de la compresión diametral con un índice de significación α=0.05. Con respecto a la prueba de microdureza de Knoop, G1 (35,73 ± 6,2) tuvo los valores más bajos, seguido de G2, mientras que G3 y G4 no mostraron diferencias estadísticas entre ellos. Para la prueba de compresión diametral, G1 (1387.76 ± 190.51) obtuvo el valor más bajo en comparación con los otros grupos. G2, G3 y G4 no presentaron diferencias estadísticamente significativas. Los diferentes tiempos de polimerización influyeron en la microdureza de Knoop y la resistencia a la compresión diametral de la resina compuesta mono incremental.

Individualized flow-controlled ventilation compared to best clinical practice pressure-controlled ventilation: a prospective randomized porcine study.

BACKGROUND: Flow-controlled ventilation is a novel ventilation method which allows to individualize ventilation according to dynamic lung mechanic limits based on direct tracheal pressure measurement at a stable constant gas flow during inspiration and expiration. The aim of this porcine study was to compare individualized flow-controlled ventilation (FCV) and current guideline-conform pressure-controlled ventilation (PCV) in long-term ventilation. METHODS: Anesthetized pigs were ventilated with either FCV or PCV over a period of 10 h with a fixed FiO2 of 0.3. FCV settings were individualized by compliance-guided positive end-expiratory pressure (PEEP) and peak pressure (Ppeak) titration. Flow was adjusted to maintain normocapnia and the inspiration to expiration ratio (I:E ratio) was set at 1:1. PCV was performed with a PEEP of 5 cm H2O and Ppeak was set to achieve a tidal volume (VT) of 7 ml/kg. The respiratory rate was adjusted to maintain normocapnia and the I:E ratio was set at 1:1.5. Repeated measurements during observation period were assessed by linear mixed-effects model. RESULTS: In FCV (n = 6), respiratory minute volume was significantly reduced (6.0 vs 12.7, MD - 6.8 (- 8.2 to - 5.4) l/min; p < 0.001) as compared to PCV (n = 6). Oxygenation was improved in the FCV group (paO2 119.8 vs 96.6, MD 23.2 (9.0 to 37.5) Torr; 15.97 vs 12.87, MD 3.10 (1.19 to 5.00) kPa; p = 0.010) and CO2 removal was more efficient (paCO2 40.1 vs 44.9, MD - 4.7 (- 7.4 to - 2.0) Torr; 5.35 vs 5.98, MD - 0.63 (- 0.99 to - 0.27) kPa; p = 0.006). Ppeak and driving pressure were comparable in both groups, whereas PEEP was significantly lower in FCV (p = 0.002). Computed tomography revealed a significant reduction in non-aerated lung tissue in individualized FCV (p = 0.026) and no significant difference in overdistended lung tissue, although a significantly higher VT was applied (8.2 vs 7.6, MD 0.7 (0.2 to 1.2) ml/kg; p = 0.025). CONCLUSION: Our long-term ventilation study demonstrates the applicability of a compliance-guided individualization of FCV settings, which resulted in significantly improved gas exchange and lung tissue aeration without signs of overinflation as compared to best clinical practice PCV.

Speckle-Tracking Echocardiography in Cardio-Oncology and Beyond.

Speckle-tracking echocardiography has enabled clinicians to detect changes in myocardial function with more sensitivity than that afforded by traditional diastolic and systolic functional measurements, including left ventricular ejection fraction. Speckle-tracking echocardiography enables evaluation of myocardial strain in terms of strain (percent change in length of a myocardial segment relative to its length at baseline) and strain rate (strain per unit of time). Both measurements have potential for use in diagnosing and monitoring the cardiovascular side effects of cancer therapy. Regional and global strain measurements can independently predict outcomes not only in patients who experience cardiovascular complications of cancer and cancer therapy, but also in patients with a variety of other clinical conditions. This review and case series examine the clinical applications and overall usefulness of speckle-tracking echocardiography in cardio-oncology and, more broadly, in clinical cardiology.

Estrés y desempeño laboral de los colaboradores de una red de salud / Stress and work performance of a health network staff

El estudio tuvo el objetivo de establecer la relación entre el estrés y el desempeño laboral de los colaboradores de la Red de Salud de Trujillo en 2019. Durante el proceso investigativo se siguió una metodología no experimental, a través de un estudio correlacional, de corte transversal, con un enfoque mixto; en el que participaron 98 colaboradores de ese entorno. Los investigadores realizaron el análisis empleando dos variables relacionadas con el ambiente laboral: estrés y desempeño. El 98% de los colaboradores mostró niveles medio y alto de estrés laboral y el 39,8% tuvo un desempeño laboral catalogado como regular. Se concluyó que el coeficiente de Rho de Spearman permitió establecer una correlación negativa y moderada entre estrés y desempeño laborales.

The study aimed to establish the relationship between stress and work performance of the staff of the Trujillo Health Network in 2019. During the research process, a non-experimental methodology was followed, through a correlational, cross-sectional study, with a mixed approach; in which 98 collaborators from that environment participated. The researchers carried out the analysis using two variables related to the work environment: stress and performance. Most of the collaborators (98%) showed medium and high levels of work stress and 39.8% had a work performance classified as regular. It was concluded that the Spearman's Rho coefficient allowed establishing a negative and moderate correlation between stress and work performance.

Optimized Modeled Myofascial Release Enhances Wound Healing in 3-Dimensional Bioengineered Tendons: Key Roles for Fibroblast Proliferation and Collagen Remodeling.

OBJECTIVE: The purpose of this study was to evaluate the mechanisms of action of optimized myofascial release (MFR) on wound healing using a 3-dimensional human tissue construct. METHODS: Bioengineered tendons were cultured on a deformable matrix, wounded using a steel cutting tip, then strained in an acyclic manner with a modeled MFR paradigm at 103% magnitude for 5 minutes. Imaging and measurements of the width and wound size were performed daily, and the average tissue width of the entire bioengineered tendon was measured, and wound size and major and minor axes of the elliptical wound were additionally measured. Assessments of actin and collagen were performed by immunofluorescence, and Gomori's trichrome staining and fibroblast nuclei deposition was quantified using the CellProfiler analysis software. RESULTS: Optimized modeled MFR treatment significantly reduced the wound size and increased both collagen density and cell deposition at the wound site. All measures of wound healing improvements required the presence of proliferating fibroblasts. CONCLUSION: Myofascial release-induced cell deposition and collagen density at wound sites required actively proliferating fibroblasts. If clinically translatable, our results support a mechanism by which MFR improves patient wound healing.

Acute Physical Stress Preconditions the Heart Against Ischemia/Reperfusion Injury Through Activation of Sympathetic Nervous System / Estresse Físico Agudo Precondiciona o Coração Contra a Injúria por Isquemia/Reperfusão Através da Ativação do Sistema Nervoso Simpático

Abstract Background: Stress is defined as a complicated state that related to homeostasis disturbances, over-activity of the sympathetic nervous system and hypothalamus-pituitary-adrenal axis responses. Cardiac preconditioning reduces myocardial damages. Objective: This study was designed to assess the cardioprotective effects of acute physical stress against ischemia/reperfusion (I/R) injury through the activation of the sympathetic nervous system. Methods: Thirty-two male Wistar rats were divided into four groups; (1) IR (n = 8): rats underwent I/R, (2) Acute stress (St+IR) (n = 8): physical stress induced 1-hour before I/R, (3) Sympathectomy (Symp+IR) (n = 8): chemical sympathectomy was done 24-hours before I/R and (4) Sympathectomy- physical stress (Symp+St+IR) (n = 8): chemical sympathectomy induced before physical stress and I/R. Chemical sympathectomy was performed using 6-hydroxydopamine (100 mg/kg, sc). Then, the hearts isolated and located in the Langendorff apparatus to induce 30 minutes ischemia followed by 120 minutes reperfusion. The coronary flows, hemodynamic parameters, infarct size, corticosterone level in serum were investigated. P < 0.05 demonstrated significance. Results: Physical stress prior to I/R could improve left ventricular developed pressure (LVDP) and rate product pressure (RPP) of the heart respectively, (63 ± 2 versus 42 ± 1.2, p < 0.05, 70 ± 2 versus 43 ± 2.6, p < 0.05) and reduces infarct size (22.16 ± 1.3 versus 32 ± 1.4, p < 0.05) when compared with the I/R alone. Chemical sympathectomy before physical stress eliminated the protective effect of physical stress on I/R-induced cardiac damages (RPP: 21 ± 6.6 versus 63 ± 2, p < 0.01) (LVDP: 38 ± 4.5 versus 43 ± 2.6, p < 0.01) (infarct size: 35 ± 3.1 versus 22.16 ± 1.3, p < 0.01). Conclusion: Findings indicate that acute physical stress can act as a preconditional stimulator and probably, the presence of sympathetic nervous system is necessary.

Resumo Fundamento: O estresse é definido como um estado complicado de distúrbios da homeostase, hiperatividade do sistema nervoso simpático e das respostas do eixo hipotálamo-hipófise-adrenal. O pré-condicionamento cardíaco diminui os danos do miocárdio. Objetivo: Esse estudo avaliou os efeitos cardioprotetores do estresse físico agudo contra a lesão por isquemia-reperfusão (I/R) através da ativação do sistema nervoso simpático. Métodos: Trinta e dois ratos machos Wistar foram divididos em quatro grupos; (1) IR (n = 8): ratos submetidos a I/R, (2) Estresse agudo (St+IR) (n = 8): estresse físico induzido 1 hora antes da I/R, (3) Simpatectomia (Symp+IR) (n = 8): a simpatectomia química foi realizada 24 horas antes da I/R e (4) Simpatectomia-estresse físico (Symp+St+IR) (n = 8): simpatectomia induzida antes do estresse físico e da I/R. A simpatectomia química foi realizada com 6-hidroxidopamina (100 mg/kg, SC). Em seguida, os corações foram isolados e colocados em aparato de Lagendorff por 30 minutos para induzir isquemia, seguida de reperfusão por 120 minutos. Os fluxos coronarianos, os parâmetros hemodinâmicos, o tamanho do infarto e os níveis de corticosterona plasmática foram investigados. Valores de p < 0,05 foram considerados significativos. Resultados: O estresse físico anterior à I/R pode melhorar a pressão desenvolvida no ventrículo esquerdo (PDVE) e duplo produto (DP), respectivamente, (63 ± 2 versus 42 ± 1,2, p < 0,05, 70 ± 2 versus 43 ± 2,6, p < 0,05) e reduzir o tamanho do infarto (22,16 ± 1,3 versus 32±1,4, p < 0,05) quando comparado com a I/R isoladamente. A simpatectomia química antes do estresse físico eliminou o efeito protetor do estresse físico sobre os danos cardíacos induzidos pela I/R (DP: 21 ± 6,6 versus 63 ± 2, p < 0,01) (PDVE: 38 ± 4,5 versus 43 ± 2,6, p < 0,01) (tamanho do infarto: 35 ± 3,1 versus 22,16 ± 1,3, p < 0,01). Conclusão: Os achados indicam que o estresse físico agudo pode funcionar como um estimulador pré-condicional e, provavelmente, a presença do sistema nervoso simpático é necessária.

[Design and finite element analysis of customized pelvic prosthesis].

OBJECTIVE: To introduce the design of customized pelvic prosthesis, to evaluate the biomechanical property under three load conditions of customized pelvic prosthesis under three load cinditions. METHODS: A titanium alloy prosthesis for reconstruction of pelvic tumors was designed by CAD software. The strength and stiffness of the custom prosthesis under static and slow gait conditions were analyzed and evaluated by finite element method. RESULTS: The results of the finite element analysis suggested that the maximum von Mises stress in the pelvic under three load conditions were 39.0, 202.8 and 42.4 MPa; the maximum displacement were 0.199, 0.766 and 0.847 mm. The maximum von Mises stress in the prosthesis under three load conditions were 62.3, 318 and 468 MPa. The maximum Von Mises stress in the Ti-alloy prosthesis and pelvic was far smaller than the yield strength of Ti-alloy. CONCLUSIONS: The study can design the size and shape of prosthesis accurately according to patient's condition. The finite element method can reduce the bone stress level and fracture risk, prolong the service life of prostheses, and ensure the safety and stability of the postoperative patients under normal gait.

Localization of Atypical Femoral Fracture on Straight and Bowed Femurs.

BACKGROUND: To elucidate the effect of anterolateral bowing on the fracture height of atypical femoral fractures (AFFs), we separated the AFFs into 2 groups according to the presence of anterolateral femoral bowing (straight group and bowing group) and analyzed the fracture height. The aims of this study were to evaluate the clinical and radiological features of AFFs in the straight group and bowing group, and to determine which factors were associated with the fracture height of AFFs in the total cohort and each subgroup. METHODS: Ninety-nine patients with AFFs were included in this study (43 patients in the bowing group and 56 patients in the straight group). Clinical and radiological characteristics were compared between the groups. Multivariable linear regression analysis was performed to determine the effect of factors on fracture height. RESULTS: Patients in the straight group were younger, heavier, and taller, and had a higher bone mineral density, smaller anterior and lateral bowing angles, and more proximal fracture height than those in the bowing group. Multivariable analysis showed that the presence of anterolateral bowing itself and height were associated with fracture height in the total cohort. In the subgroup analysis, the lateral bowing angle in the straight group and the estimated apex height in the bowing group were associated with fracture height. The lateral bowing angle was not significantly associated with fracture height in the total cohort and the bowing group. CONCLUSIONS: The presence of anterolateral bowing and the level of the apex of the bowed femur were important factors for the fracture height of AFFs.

Shear-Sensitive lncRNA AF131217.1 Inhibits Inflammation in HUVECs via Regulation of KLF4.

Atherosclerosis is one of the most common vascular diseases, and inflammation participates in all stages of its progression. Laminar shear stress protects arteries from atherosclerosis and reduces endothelial inflammation. Long noncoding RNAs have emerged as critical regulators in many diseases, including atherosclerosis. However, the expression and functions of long noncoding RNAs subjected to laminar shear stress in endothelial cells remain unclear. This study aimed to reveal the mechanism by which shear stress-regulated long noncoding RNAs contribute to anti-inflammation. In this study, we identified a novel long noncoding RNA AF131217.1, which was upregulated after laminar shear stress treatment in human umbilical vein endothelial cells. Knockdown of AF131217.1 inhibited flow-mediated reduction of monocyte adhesion VCAM-1 (vascular cell adhesion molecule-1) and ICAM-1 (intercellular adhesion molecule-1) expression and inhibited flow-mediated enhancement of flow-responsive expression of KLF (Kruppel-like factor) 2 and eNOS (endothelial NO synthase). Furthermore, TNF-α (tumor necrosis factor-α) was used to induce an inflammatory response in human umbilical vein endothelial cells. Knockdown of AF131217.1 promoted ICAM-1 and VCAM-1 expression, as well as changes in monocyte adhesion and KLF2 and eNOS expression induced by TNF-α. Mechanistic investigations indicated that AF131217.1 acted as a competing endogenous RNA for miR-128-3p, leading to regulation of its target gene KLF4. In conclusion, our study demonstrates for the first time that laminar shear stress regulates the expression of AF131217.1 in human umbilical vein endothelial cells, and the AF131217.1/miR-128-3p/KLF4 axis plays a vital role in atherosclerosis development.

[Three-dimensional finite element analysis of the stress distribution of bone tissue around porous titanium implant].

Objective: To analyze the stress distribution of different types of bone tissue around porous titanium implant in different mechanical loads and to further evaluate the biomechanical properties of porous titanium implant. Methods: Finite element (FE) models of implant restorations for the maxillary first premolar was established, and the diameter of implants in the models was 4.1 mm. Five models was constructed according to diameter of implant central pillar and the thickness of outer porosity: solid group (group A), central pillar 1.5 and 3.1 mm and outer porosity 30% (group B and C), central pillar 1.5 and 3.1 mm and outer porosity 40% (group D and E). Different loads (150 N vertical force, 50 N lateral force) were applied to the occlusal surface of implant restorations in type Ⅲ bone and maximal von Mises stress was evaluated. Meanwhile, a couple of simplified maxillary part models varied in four types of bone were constructed with the implants bearing load of simulation ultimate force to evaluate the stress distribution of different types of bone. Results: With different mechanical loading, the stress value of bone tissue around porous implant (group B-E) was greater than that in the solid structure (group A). Under the load of simulation ultimate force, the maximum stress of the bone rised with the increase of porosity and thickness of the porous implant. And the maximum stress value of the surrounding bone tissue changed with the change of bone. Under vertical loading, the maximal von Mises stress of the bone around solid implants of group A was 17.56 MPa, which was a little lower than that of group B and C. And the maximal equivalent von Mises stress of group D and E was 69.24 MPa. The results of lateral force and simulation ultimate force loading were similar. The stress of the bone tissue around implant increased with the decrease of bone quality. The maximum stress value of group D implant was 134.95 MPa. Conclusions: Porous structure of the implant is conducive to transmit stress to surrounding bone tissue and increases the mechanical stimulation of bone. However, if the value and direction of load are inappropriate or quality of bone is poor, pathological stress may be produced.

Myocardial volume change during cardiac cycle derived from three orthogonal systolic strains: towards a quality assessment of strains.

BACKGROUND: The relative modification of the myocardial volume between end-systole and end-diastole ( Vs/d=Vend-systole/Vend-diastole ) has already been assessed with different methods and falls in a range of 0.9-0.97 (mean value = 0.93). PURPOSE: To estimate Vs/d from the three longitudinal ( ɛl) , circumferential ( ɛc ), and radial ( ɛr ) strains of the left ventricle using the formula: Vs/d=(1+ɛc)(1+ɛr)(1+ɛl) and to test whether this estimate of Vs/d can be used as a marker of the echocardiography quality. MATERIAL AND METHODS: Two hundred manuscripts, including a total of 34,690 patients or healthy volunteers, were identified in the Medline database containing values of ɛl , ɛc , and ɛr measured from echocardiography. RESULTS: The median value of was 0.93, in accordance with the literature, with no significant difference between patients or healthy volunteers ( P = 0.38). The proportion of studies with Vs/d=0.93±0.1 was 79%. When only considering groups of healthy volunteers, the studies failing this test had higher standard deviations for the three individual strains: 0.038 vs. 0.029 ( P = 0.02) for ɛl ; 0.060 vs. 0.034 ( P < 10-6) for ɛc , and 0.243 vs. 0.101 ( P < 10-14) for ɛr . CONCLUSION: The median ratio of the left ventricular myocardial volumes between end-systole and end-diastole in the investigated studies was Vs/d=0.93 . The formula (1+ɛc)(1+ɛr)(1+ɛl)∉[0.83;1.03] could be used to detect studies with inaccurate strain measurements.

Localization of Atypical Femoral Fracture on Straight and Bowed Femurs

BACKGROUND: To elucidate the effect of anterolateral bowing on the fracture height of atypical femoral fractures (AFFs), we separated the AFFs into 2 groups according to the presence of anterolateral femoral bowing (straight group and bowing group) and analyzed the fracture height. The aims of this study were to evaluate the clinical and radiological features of AFFs in the straight group and bowing group, and to determine which factors were associated with the fracture height of AFFs in the total cohort and each subgroup. METHODS: Ninety-nine patients with AFFs were included in this study (43 patients in the bowing group and 56 patients in the straight group). Clinical and radiological characteristics were compared between the groups. Multivariable linear regression analysis was performed to determine the effect of factors on fracture height. RESULTS: Patients in the straight group were younger, heavier, and taller, and had a higher bone mineral density, smaller anterior and lateral bowing angles, and more proximal fracture height than those in the bowing group. Multivariable analysis showed that the presence of anterolateral bowing itself and height were associated with fracture height in the total cohort. In the subgroup analysis, the lateral bowing angle in the straight group and the estimated apex height in the bowing group were associated with fracture height. The lateral bowing angle was not significantly associated with fracture height in the total cohort and the bowing group. CONCLUSIONS: The presence of anterolateral bowing and the level of the apex of the bowed femur were important factors for the fracture height of AFFs.

Design and finite element analysis of customized pelvic prosthesis / 中国骨伤

OBJECTIVE@#To introduce the design of customized pelvic prosthesis, to evaluate the biomechanical property under three load conditions of customized pelvic prosthesis under three load cinditions.@*METHODS@#A titanium alloy prosthesis for reconstruction of pelvic tumors was designed by CAD software. The strength and stiffness of the custom prosthesis under static and slow gait conditions were analyzed and evaluated by finite element method.@*RESULTS@#The results of the finite element analysis suggested that the maximum von Mises stress in the pelvic under three load conditions were 39.0, 202.8 and 42.4 MPa; the maximum displacement were 0.199, 0.766 and 0.847 mm. The maximum von Mises stress in the prosthesis under three load conditions were 62.3, 318 and 468 MPa. The maximum Von Mises stress in the Ti-alloy prosthesis and pelvic was far smaller than the yield strength of Ti-alloy.@*CONCLUSIONS@#The study can design the size and shape of prosthesis accurately according to patient's condition. The finite element method can reduce the bone stress level and fracture risk, prolong the service life of prostheses, and ensure the safety and stability of the postoperative patients under normal gait.