Patterns in Protein Flexibility: A Comparison of NMR "Ensembles", MD Trajectories, and Crystallographic B-Factors.

Proteins are molecular machines requiring flexibility to function. Crystallographic B-factors and Molecular Dynamics (MD) simulations both provide insights into protein flexibility on an atomic scale. Nuclear Magnetic Resonance (NMR) lacks a universally accepted analog of the B-factor. However, a lack of convergence in atomic coordinates in an NMR-based structure calculation also suggests atomic mobility. This paper describes a pattern in the coordinate uncertainties of backbone heavy atoms in NMR-derived structural "ensembles" first noted in the development of FindCore2 (previously called Expanded FindCore: DA Snyder, J Grullon, YJ Huang, R Tejero, GT Montelione, Proteins: Structure, Function, and Bioinformatics 82 (S2), 219-230) and demonstrates that this pattern exists in coordinate variances across MD trajectories but not in crystallographic B-factors. This either suggests that MD trajectories and NMR "ensembles" capture motional behavior of peptide bond units not captured by B-factors or indicates a deficiency common to force fields used in both NMR and MD calculations.

Fracture strength analysis of titanium insert-reinforced zirconia abutments according to the axial height of the titanium insert with an internal connection.

This study aimed to analyze fracture strength in vitro by varying the axial height of the titanium insert and the labial height of the zirconia abutment in an internal connection implant to identify the titanium insert axial height with optimal mechanical stability. Sixty implants with an internal connection system were used. Two-piece zirconia abutments were used with the titanium inserts. Combinations of different titanium insert axial heights (mm) and zirconia abutment labial heights (mm) constituted five groups: Gr1 (1-3), Gr2 (3-3), Gr3 (3-5), Gr4 (5-3), and Gr5 (5-5). After thermocycling, a fracture load test was performed with a universal testing machine. The initial deformation load and the fracture load were measured and analyzed. The fractured surface and cross-section of the specimens were examined by scanning electron microscopy (SEM). The groups of titanium inserts with axial heights of 3 mm and 5 mm showed significantly greater initial deformation load and fracture load than the group with an axial height of 1 mm (p < 0.05), but there was no significant difference between the two groups with axial heights of 3 mm and 5 mm. The labial height of the zirconia abutment had no significant influence on the initial deformation load and fracture load. In some specimens in Gr4 and Gr5, cracking or bending of the titanium insert and abutment screw was observed on SEM. The axial height of the titanium insert should be designed to not be less than 3 mm to increase the fracture strength and promote the long-term stability of implants.

Relationship between upper limb injuries and hip range of motion and strength in high school baseball pitchers.

We aimed to examine the relationship between hip range of motion (ROM) and abduction strength and throwing-related shoulder/elbow injuries in high school baseball pitchers. The study included 135 baseball pitchers. We asked them to fill out a questionnaire at the checkups, that included the dominant arm and the years of baseball experience. To avoid a confirmation bias, the examiners were blinded to the participants' hand dominance. All players underwent physical function measurements, such as height, weight, shoulder and hip strength, and shoulder and hip ROM. Shoulder and elbow injury was defined as shoulder and elbow pain that the patient had been aware of in the past 3 years. The results of injured and non-injured pitchers were compared. Eighty-five pitchers had experienced a shoulder or elbow injury in the past 3 years. The shoulder ROM and strength in the injured and non-injured groups did not differ to a statistically significant extent. The hip external rotation ROM on the dominant side, the hip abduction strength on the non-dominant side, and the hip abduction strength on the dominant side were significantly lower in the injured group than in the non-injured group. The results may contribute to reducing the incidence of these injuries.

The effect of gluteus maximus tenotomy in primary total hip arthroplasty with posterior approach: Kinematic analysis of hip extensor strength.

BACKGROUND: The posterior approach (PA) is the most commonly used surgical approach for total hip arthroplasty (THA), but the proximity of the sciatic nerve may increase the likelihood of sciatic nerve injury (SNI). Gluteus maximus tenotomy can be performed to prevent SNI because tenotomy increases the distance between the femoral neck and sciatic nerve and prevents compression of the sciatic nerve by the gluteus maximus tendon (GMT) during hip movements. We aimed to kinematically compare the postoperative hip extensor forces of patients who have and have not undergone gluteus maximus tenotomy to determine whether there is a difference in hip extensor strength. METHODS: Seventy-two patients who underwent gluteus maximus tenotomy during THA were included in the group 1, and 86 patients who did not undergo tenotomy were included in group 2. The Harris hip score, body mass index and hip extensor forces were measured both preoperatively, and 6 months after surgery with an isokinetic dynamometer and compared. RESULTS: The mean age was 64.6 ± 2.3 years in group 1 and 63.8 ± 2.1 in group 2. Mean body mass index was 25.7 ± 1.1 in group 1, and 25.5 ± 1.3 in group 2. Baseline Harris hip score (HHS) was 42.36 ± 12 in group 1 and 44.07 ± 9.4 in group 2 (p = 0.31), whereas it was 89.1 ± 7.8 and 88.4 ± 8.1 at 6 months after surgery, respectively. Baseline hip extensor force (HEF) was 2 ± 0.4 Nm/kg in group 1, and 2.1 ± 0.7 Nm/kg in group 2 (p = 0.28), while it was 2.4 ± 0.6 Nm/kg, and 2.5 ± 0.5 Nm/kg, respectively at 6 month follow-up (p = 0.87). Both groups had significantly improved HHS and HEF when comparing baseline and postoperative measurements (p < 0.0001). No cases of sciatic nerve palsy were noted in group 1, whereas there were two (2.32%) cases in group 2, postoperatively. CONCLUSION: The release of the GMT during primary hip arthroplasty performed with the PA did not lead to significant decrease in hip extension forces. Hip extensor strength improves after THA regardless of tenotomy. Gluteus maximus tenotomy with repair does not reduce muscle strength and may offer better visualization.

In Men With Obesity, T2DM Is Associated With Poor Trabecular Microarchitecture and Bone Strength and Low Bone Turnover.

INTRODUCTION: Obesity and type 2 Diabetes (T2D) are both associated with greater bone mineral density (BMD) but increased risk of fractures. The effect of the combination of both conditions on bone metabolism, microarchitecture, and strength in the obese population remains unknown. METHODS: Data from 112 obese men were collected. Bone turnover and biochemical markers were measured by enzyme-linked immunosorbent assay, body composition and BMD at all sites were assessed by dual energy X-ray absorptiometry, whereas bone microarchitecture and strength (stiffness and failure load) were measured by high-resolution peripheral computed tomography. Data were compared among metabolically healthy obese (MHO) and metabolically unhealthy obese (MUHO) with and without T2D and between obese without and with T2D. RESULTS: Compared to MHO and MUHO without T2D, MUHO with T2D had significantly lower levels of osteocalcin ((7.49 ±â€…3.0 and 6.03 ±â€…2.47 vs 4.24 ±â€…2.72 ng/mL, respectively, P = 0.003) and C-terminal telopeptide of type I collagen (CTx) (0.28 ±â€…0.10 and 0.29 ±â€…0.13 vs 0.21 ±â€…0.15 ng/mL, respectively, P = 0.02). Dividing our subjects simply into those with and without T2D showed that obese men with T2D had significantly lower levels of osteocalcin (P = 0.003) and CTx (P = 0.005), greater trabecular separation at the tibia and radius (P = 0.03 and P = 0.04, respectively), and lower tibial failure load and stiffness (both P = 0.04), relative to obese men without T2D. CONCLUSION: In men, the combination of obesity and T2D is associated with reduced bone turnover and poorer trabecular bone microarchitecture and bone strength compared to those who are obese but without T2D, suggesting worse bone disease.

Investigation of Mechanical, Material, and Compositional Determinants of Human Trabecular Bone Quality in Type 2 Diabetes.

CONTEXT: Increased bone fragility and reduced energy absorption to fracture associated with type 2 diabetes (T2D) cannot be explained by bone mineral density alone. This study, for the first time, reports on alterations in bone tissue's material properties obtained from individuals with diabetes and known fragility fracture status. OBJECTIVE: To investigate the role of T2D in altering biomechanical, microstructural, and compositional properties of bone in individuals with fragility fracture. METHODS: Femoral head bone tissue specimens were collected from patients who underwent replacement surgery for fragility hip fracture. Trabecular bone quality parameters were compared in samples of 2 groups, nondiabetic (n = 40) and diabetic (n = 30), with a mean duration of disease 7.5 ± 2.8 years. RESULTS: No significant difference was observed in aBMD between the groups. Bone volume fraction (BV/TV) was lower in the diabetic group due to fewer and thinner trabeculae. The apparent-level toughness and postyield energy were lower in those with diabetes. Tissue-level (nanoindentation) modulus and hardness were lower in this group. Compositional differences in the diabetic group included lower mineral:matrix, wider mineral crystals, and bone collagen modifications-higher total fluorescent advanced glycation end-products (fAGEs), higher nonenzymatic cross-link ratio (NE-xLR), and altered secondary structure (amide bands). There was a strong inverse correlation between NE-xLR and postyield strain, fAGEs and postyield energy, and fAGEs and toughness. CONCLUSION: The current study is novel in examining bone tissue in T2D following first hip fragility fracture. Our findings provide evidence of hyperglycemia's detrimental effects on trabecular bone quality at multiple scales leading to lower energy absorption and toughness indicative of increased propensity to bone fragility.

El fenómeno de flexión-relajación lumbar como test diagnóstico en la evaluación de un déficit lumbar. Sensibilidad y especificidad / The lumbar flexion-relaxation phenomen as a diagnostic test in assessment of lumbar impairment. Sensitivity and specificity

OBJETIVO: Definir el papel del fenómeno de flexión-relajación (FR), valorado mediante ratios (FRR), como test diagnóstico para definir una situación de déficit (impairment) en pacientes con dolor lumbar crónico (DLC). MATERIAL Y MÉTODO: La muestra del estudio consta de 180 sujetos, 16 voluntarios sanos y 164 pacientes en situación de incapacidad laboral por DLC, que fueron remitidos consecutivamente desde enero de 2012 a diciembre de 2017 para su valoración al laboratorio de biomecánica de una mutua de accidentes de trabajo. Las evaluaciones consistieron en un test de dinamometría isométrica, una prueba cinemática y una valoración del fenómeno FR. Se establecieron unos criterios mínimos en la ejecución de los test para ser aceptados como pruebas válidas para el estudio. El estado de déficit lumbar o de recuperación clínica en un paciente se definió a partir de los test de dinamometría y de cinemática. La respuesta FR se valoró con los FRR. Se tomaron un total de 4 ratios diferentes para el análisis con curvas ROC. RESULTADOS: Se obtuvieron 86 pruebas válidas (16 clasificadas como déficit lumbar y 71 como casos recuperados). La mejor ratio obtiene un área bajo la curva ROC de 0,87, una S: 0,84 y una E: 0,87 para identificarlos y un valor predictivo positivo del 97%. CONCLUSIONES: El test FR guarda con las evaluaciones de dinamometría y de cinemática una alta coherencia para objetivar una situación de déficit, siendo este una prueba de fácil ejecución por parte de los pacientes con DLC

OBJECTIVE: To define the role of the flexion-relaxation phenomenon (FRP), assessed through ratios (FRR), as a diagnostic test to define impairment in patients with chronic low back pain (CLBP). MATERIAL AND METHOD: The study sample consisted of 180 participants (16 healthy volunteers and 164 patients on work disability due to CLBP), who were consecutively referred for evaluation at the Biomechanics Laboratory of a workplace accident insurance company from January 2012 to December 2017. The evaluations consisted of an isometric dynamometry test, a kinematic test and assessment of the FRP phenomenon. Minimum criteria were established in the performance of the tests for their acceptance as valid for the study. Lumbar impairment or clinical recovery was defined on the basis of the results of the dynamometry and kinematic tests. The FRP response was assessed with FRRs. A total of 4 different ratios were taken for analysis with ROC curves. RESULTS: A total of 86 valid tests were obtained (16 classified as lumbar impairment and 71 as recovered cases). The best ratio obtained an area under the ROC curve of 0.87, with a sensitivity of 0.84, a specificity of 0.87, and a positive predictive value of 97%. CONCLUSION: The FRP test, along with dynamometry and kinematic evaluations, is effective in identifying lumbar impairment and is the easiest test for patients with CLBP to perform

Rotary-jet spun polycaprolactone/nano-hydroxyapatite scaffolds modified by simulated body fluid influenced the flexural mode of the neoformed bone.

Polycaprolactone (PCL) is a biocompatible, biodegradable synthetic polymer which in combination with nanohydroxyapatite (nHAp) can give rise to a low cost, nontoxic bioactive product with excellent mechanical properties and slow degradation. Here we produced, characterized and evaluated in vivo the bone formation of PCL/nHAp scaffolds produced by the rotary jet spinning technique. The scaffolds produced were firstly soaked into simulated body fluid for 21 days to also obtain nHAp onto PCL/nHAp scaffolds. Afterwards, the scaffolds were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy and Raman spectroscopy. For in vivo experiments, 20 male Wistar rats were used and randomly divided in 4 experimental groups (n = 5). A critical defect of 3 mm in diameter was made in the tibia of the animals, which were filled with G1 control (clot); G2-PCL scaffold; G3-PCL/nHAp (5%) scaffold; G4-PCL/nHAp (20%) scaffold. All animals were euthanized 60 days after surgery, and the bone repair in the right tibiae were evaluated by radiographic analysis, histological analysis and histomorphometric analysis. While in the left tibias, the areas of bone repair were submitted to the flexural strength test. Radiographic and histomorphometric analyses no showed statistical difference in new bone formation between the groups, but in the three-point flexural tests, the PCL/nHAp (20%) scaffold positively influenced the flexural mode of the neoformed bone. These findings indicate that PCL/nHAp (20%) scaffold improve biomechanical properties of neoformed bone and could be used for bone medicine regenerative.

Pretratamiento y mejoría de la fuerza de unión de los cementos autoadhesivos de resina a los postes / Pretreatment and improvement of bonding strength of self-adhesive resin cements to posts

ABSTRACT Introduction: Posts and core are frequently used in endodontically treated teeth with excessive loss of coronal tooth structure. Objective: To evaluate the effectiveness of self-adhesive cements under different pre-treatments of dentin in the resistance to extrusion of fiberglass posts. Methods: An experimental in vitro study was conducted. The randomly selected sample was 56 extracted bovine incisors with mature apices and without root curvature. Before the cementing procedure, pretreatment of dentin was performed with 11.5 percent polyacrylic acid, 17 percent EDTA or sodium hypochlorite. The type of failure between the post/cement/dentin was evaluated by stereomicroscope. Two hundred and sixteen bovine dentin discs were used. The disks were approximately 1 mm thick, and were obtained from 72 bovine roots restored with intraradicular retentions. Data were analyzed for better comprehension in an SPSS database for Windows version 15. Results: The highest values were found in groups G3, G4 and G5, and there was no bond strength significant difference in group G2. Conclusions: The pre-treatment had no effect on dentin bond strength, and the self-adhesive cement RelyX U100 appears to be a viable option in the cementation of fiber posts(AU)

RESUMEN Introducción: Los postes y el núcleo se utilizan con frecuencia en los dientes tratados endodónticamente con una pérdida excesiva de la estructura dental coronal. Objetivo: Evaluar la efectividad de los cementos autoadhesivos bajo diferentes pretratamientos de dentina en la resistencia a la extrusión de postes de fibra de vidrio. Métodos: Se realizó una investigación experimental in vitro en 56 dientes de ganado seleccionados al azar con cierre apical maduro y sin curvaturas radiculares. Antes del procedimiento de cementación, se llevó a cabo el pretratamiento de la dentina con 11,5 por ciento de ácido poliacrílico, 17 por ciento de EDTA o hipoclorito de sodio. El estereomicroscopio evaluó el tipo de falla entre el poste / cemento / dentina. Se usaron 216 discos de dentina bovina. Los discos tenían aproximadamente 1 mm de espesor y se obtuvieron de 72 raíces bovinas restauradas con retenciones intrarradiculares. Los datos se analizaron para una mejor comprensión en una base de datos de SPSS para Windows versión 15. Resultados: Los valores más elevados fueron encontrados en los grupos G3, G4 y G5 y no fue significativa la prueba de resistencia en el grupo G2. Conclusiones: El pretratamiento no tuvo efecto sobre la fuerza de unión dentinaria, y el cemento autoadhesivo RelyX U100 parece ser una opción viable en la cementación postes de fibra(AU)

Relationship between strength and flexibility levels in young soccer players / Relación entre los niveles de fuerza y flexibilidad en jóvenes jugadores de fútbol

INTRODUCTION: Balance of strength and flexibility between the dominant (DL) and non-dominant limbs (NDL) in young soccer players is essential, since it can minimize the possible injury-triggering mechanisms and their negative influence on performance. The aim of this study was to evaluate and compare the unilateral and bilateral strength and flexibility between the DL and NDL in young soccer players. MATERIAL AND METHODS: The sample consisted of 30 individuals (aged 15.97 ± 0.67 years). The isokinetic strength was measured at the velocities of 60°s and 180°s in the concentric action of the quadriceps and hamstrings as well as eccentric of the hamstrings, and in the conventional and functional ratios, along with hip flexion range of motion. RESULTS: The results showed the athletes had an eccentric strength of the hamstrings at 60°s in the DL significantly (p < 0.05) stronger than in the NDL, and the DL had a significant H/Q ratio (p < 0.05) more balanced than the NDL. CONCLUSIONS: Young soccer athletes may present a non-standard isokinetic results. These results are observed because of the difference in muscle strength of the posterior thigh compared to DL and NDL and the balance relation between the quadriceps and the hamstrings, generating an asymmetry of strength between the limbs and on the same member. It is necessary to monitor and devise training strategies to avoid these imbalances in order to prevent injuries

INTRODUCCIÓN: El equilibrio de la fuerza y de la flexibilidad entre las piernas dominantes (PD) y no dominantes (PND) en jóvenes jugadores de fútbol es imprescindible, pues puede minimizar los posibles mecanismos desencadenantes de lesiones y su influencia negativa en el desempeño. El objetivo de este estudio fue evaluar y comparar la fuerza y la flexibilidad uni y bilateral entre las PD y PND en jóvenes jugadores de fútbol. MATERIAL Y MÉTODOS: La muestra fue compuesta por 30 individuos (con edad entre 15,97 ± 0,67 años). Se evaluó la fuerza isocinética a las velocidades de 60°/s y 180°/s en la acción concéntrica del cuádriceps e isquiotibiales y excéntrica de los isquiotibiales, y en las razones convencional y funcional, además de la goniometría para la flexión de cadera. RESULTADOS: Los resultados demostraron que los atletas poseían una acción excéntrica de los isquiotibiales en 60°/s en las PD significativamente (p < 0,05) más fuerte que en las PND, además de las PD tener una relación I/Q significativamente (p < 0,05) más equilibrada que las PND. CONCLUSIONES: Los atletas jóvenes de fútbol pueden presentar resultados isocinéticos no estandarizados. Estos resultados se observan debido a la diferencia en la fuerza muscular del muslo posterior con relación a las PD y PND y la relación de equilibrio entre el cuádriceps y los isquiotibiales, generando una asimetría de fuerza entre los miembros y en el mismo miembro. Es necesario monitorear y elaborar estrategias de entrenamiento para evitar estos desequilibrios, a fin de evitar lesiones

Jump Exercise and Food Restriction on Bone Parameters in Young Female Rats.

We examined the effect of jump exercise on bone parameters in young female rats under food restriction. Seven-week-old female rats were divided into four groups: a sedentary and ad libitum feeding group (n = 10), a jump exercise and ad libitum feeding group (n = 9), a sedentary and 30% food restriction group (n = 9), and a jump exercise and 30% food restriction group (n = 10). The jump groups jumped 20 times/day, 5 times/week. The experiment lasted for 13 weeks. There were no interactions of jump exercise and food restriction on bone. Jump exercise under food restriction conditions induced higher bone strength, bone mineral content, bone area, bone mineral density (BMD), and cortical bone volume in young female rats, similar to rats under ad libitum feeding conditions. Bone strength parameters were not significantly different between ad libitum intake and food restriction with jump exercise training; however, BMD, bone size, and bone mass in the food restriction groups did not reach the levels of those in the ad libitum conditions group with jump exercise training. Neither jump exercise nor food restriction had a significant effect on serum estradiol or IGF-1. Our study reveals jump exercise attenuates loss of biomechanical properties and some bone sites with food restriction in young female rats.

An Investigation on the Correlation between the Mechanical Properties of Human Skull Bone, Its Geometry, Microarchitectural Properties, and Water Content.

With increasingly detailed imaging and mechanical analysis, modalities need arises to update methodology and assessment criteria for skull bone analysis to understand how bone microarchitecture and the presence of attached tissues may affect the response to mechanical load. The main aim was to analyze the effect of macroscopic and microstructural features, as well as periosteal attachment, on the mechanical properties of human skull bone. Fifty-six skull specimens from ethanol-phenoxyethanol-embalmed cadavers were prepared from two human cadavers. Assuming symmetry of the skull, all samples from one-half each were stripped of periosteum and dura mater, while the soft tissues were kept intact on the remaining samples on the contralateral side. The specimens were analyzed using microcomputed tomography to assess trabecular connectivity density, total surface area, and volume ratio. The specimens were loaded under three-point bend tests until fracture with optical co-registration. The bone fragments were then lyophilized to measure their water content. With increasingly detailed imaging and mechanical analysis modalities, there is a need to update methodology and assessment criteria for skull bone analysis to understand how the bone microarchitecture and the presence of attached tissues may affect the response to mechanical load. The mechanical properties were negatively correlated to bone thickness and water content. Conversely, most microarchitectural features did not influence either mechanical parameter. The correlation between mechanical response data and morphologic properties remains similar between the results of embalmed tissues presented here and fresh osseous tissue from literature data. The findings presented here add to the existing methodology to assess human skull for research purposes. The interaction between most microarchitectural features in ethanol-phenoxyethanol-embalmed embalmed skull samples and bending stress appear to be minute.

Limitación del movimiento de flexión dorsal del tobillo en sujetos pronadores con dolor lumbar crónico / Limited ankle dorsiflexion in subjects with pronated feet and low back pain

Antecedentes: Estudios han relacionado la posible influencia entre los desequilibrios de la biomecánica del pie y el dolor lumbar crónico (CLBP). Según indican algunos autores la limitación del movimiento de la flexión dorsal (FD) de la articulación tibioperonea-astragalina del pie (TPA) puede presentarse como un factor de riesgo en el dolor lumbar crónico. Objetivo: Evaluar el dolor lumbar crónico en sujetos con pies pronadores con limitación de la flexión dorsal del tobillo en al menos un pie, frente a sujetos pronadores con movilidad normal del tobillo. Material y método: estudio descriptivo transversal con muestreo por conveniencia realizado en una muestra compuesta por 126 sujetos con dolor lumbar crónico y pies pronados. Se comparó un grupo de sujetos con CLBP que presentaron limitación de la flexión dorsal de al menos un tobillo, frente a otro grupo de pronadores con CLBP y rango de movimiento normal de tobillo. Como herramientas de valoración de la variable dependiente se utilizó la escala visual analógica (EVA) y el Índice de discapacidad por dolor lumbar de Oswestry (ODI). Resultados: Se encontró correlación positiva entre la limitación de FD de la TPA en sujetos pronadores con CLBP frente al grupo de pronadores con CLBP y FD normal (EVA 4 ± 0,22; ODI: 11,85% ± 1,21). La limitación del movimiento de FD de TPA parece mostrarse como un factor de riesgo en el CLBP (EVA 5,3 ± 0,22; ODI: 17,90% ± 1,42; valor de p ODI = 0,004; EVA 0,009). Conclusiones: Se evidencia un mayor CLBP en el grupo de pronadores con limitación de FD de al menos una TPA frente al grupo de sujetos pronadores con rango normal de movimiento

Background: The influence between the imbalances in foot biomechanics and chronic low back pain (CLBP) has been described in different studies. Some authors suggest that the reduced ankle (TPA) dorsiflexion (FD) can present as a risk factor in chronic low back pain. Objective: To evaluate low back pain in subjects with pronated feet and limited ankle dorsiflexion compared to those with pronated feet and normal mobility of ankle. Material and method: A cross-sectional study with convenience sampling was performed on 126 subjects with chronic low back pain and pronated feet. Participants were divided into two groups, both with pronated feet but one with reduced FD in at least one foot and the other with normal FD of TPA movement. A visual analogue scale (VAS) and the Oswestry Low Back Pain Index (ODI) were used as tools for assessing the dependent variable. Results: After the analysis of the data, a positive correlation was found between the limited FD of the movement of the TPA in pronated feet subjects with CLBP versus those who had normal mobility of TPA and pronated feet (VAS 4 ± 0,22; ODI: 11.85% ± 1.21). The limitation of the joint range of the ankle seemed to be a risk factor in CLBP in pronator subjects (VAS 5.3 ± 0.22; ODI: 17.90% ± 1.42) (ODI scale = 0.004, VAS 0.009). Conclusions: There is evidence of a higher rate of chronic lumbar pain in pronated patients with reduced ankle dorsiflexion as assessed with a VAS and the ODI scale

Diferencias motoras en atletas cadetes de taekwondo según nivel competitivo / Motor Differences in Cadet Taekwondo Athletes According to Competition Level

El objetivo de este estudio es observar las diferencias entre atletas cadetes de Taekwondo de diferentes niveles competitivos en términos antropométricos, de potencia muscular, flexibilidad y velocidad de reacción. Veinte atletas varones fueron analizados, divididos en dos grupos: medallistas nacionales y no medallistas nacionales. Para cada atleta se tomaron datos antropométricos, de velocidad de reacción, potencia muscular y rango de movimiento articular de la articulación coxofemoral. Los atletas medallistas mostraron valores significativamente menores en altura, envergadura, tiempo de reacción óculo-podal, y tiempo de reacción óculo-manual con mano no dominante; y valores mayores para longitud de piernas, flexión pasiva de cadera, y abducción de cadera tanto activa como pasiva. Las leves diferencias observadas entre grupos en potencia muscular, grasa corporal y flexión activa de cadera no concuerdan con estudios previos. Conocer está información podría ser de interés para los entrenadores para llevar a cabo programas de detección de talentos

The aim of this study was to determine the differences between Taekwondo cadet athletes belonging to different competition levels in terms of anthropometry, legs power, flexibility and reaction time. Twenty male athletes were analysed, divided in two groups: national medallist and non-national medallist. Data of every athlete's anthropometric measurements, reaction speed ability, leg power and hip ROM (range of movement) were taken. Medallist athletes showed significantly lower values for height, arm span, foot reaction time (dominant and non-dominant) and non-dominant hand reaction time; and higher values for leg length, passive hip flexion, active hip abduction and passive hip abduction in ROM tests. Slight differences observed between medallists and non-medallists in leg power (CMJ), body fat (Σ skinfolds) and active hip flexion do not agree with previous studies. Knowing this information could be interesting for coaches in order to carry out talent detection programs

Fracture Strength and Stress Distribution in Premolars Restored with Cast Post-and-Cores or Glass-Fiber Posts Considering the Influence of Ferule.

OBJECTIVES: The aim of this study was to evaluate the influence of ferule and the post type on the fracture strength and stress distribution in premolars. MATERIALS AND METHODS: Forty human mandibular premolars were decoronated, allocated in four groups, and restored as follows: CPC-NF: cast post-and-core and absence of ferule; CPC-F: cast post-and-core and presence of ferule; FPC-NF: glass-fiber posts and absence of ferule; FPC-F: glass-fiber posts and presence of ferule. The fracture strength (FS) and failure patterns were evaluated. Finite element analysis (FEA) evaluated the stress distribution. RESULTS: FS did not differ between CPCs and FPC either in presence or in absence of ferule. The presence of ferule increased FS with both post types. Mean values of FS for ferule groups were higher than functional or parafunctional loads reported in literature, which was not the case for FPC-NF when compared to parafunctional loads. FEA with a functional load showed slightly higher compressive stresses in dentin in the group CPC-NF, which was much lower than the compressive strength of dentin. Lower percentage of catastrophic failures was observed in nonferule groups irrespective of post type, which was explained by the stress concentration in the cervical root region when FEA with the FS load was simulated. CONCLUSION: Ferule effect was shown to be more important than post type in the analysis. Both posts showed potential to withstand functional loads irrespective of presence of ferule. However, the mean FS was lower than parafunctional loads for FPC in the absence of ferule.

Isokinetic flexion strength recovery after ACL reconstruction: a comparison between all inside graft-link technique and full tibial tunnel technique.

INTRODUCTION: Recently, a new minimally invasive single bundle technique for anatomic ACL reconstruction has been described, called the 'All-Inside graft-link technique'. One of the advantages of this procedure is the reduced morbidity at the donor site as the graft choice is the quadrupled semitendinosus, thus sparing the gracilis tendon. The aim of this study was to evaluate isokinetic flexion strength recovery in patients who underwent a gracilis sparing technique compared to those with a full-tibial tunnel technique using a doubled gracilis and semitendinosus tendons (DGST) graft. METHODS: Patients were divided into two groups: Group A (22 patients) who underwent ACL reconstruction performed with an All-Inside graft-link technique; Group B (22 patients) who underwent ACL reconstruction with an Out-In technique and DGST graft. At a mean follow-up of 13 months, quadriceps and hamstring isokinetic peak torque deficits were recorded. RESULTS: In group A, the mean side to side peak torque flexion difference between the operated and non-operated limbs was -3% and the mean torque at 30° was -7.5% at high angular velocity (180°/sec); the mean peak flexion torque was 7.2% and the mean torque at 30° was 3.1% at low angular velocity (60°/sec). In group B, the mean side to side peak flexion torque was -3.5% and the mean torque at 30° was -7.6% at high angular velocity (180°/sec); the mean peak flexion torque was -7.2% and the mean torque at 30° was -11% at low angular velocity (60°/sec). A statistically significant difference was found between the two groups at lower angular velocity both for the mean peak flexion torque and the mean torque at 30° (p = 0.009), with better results in the study group. DISCUSSION/CONCLUSION: Gracilis sparing technique is a minimally invasive technique for ACL reconstruction and yielded a significantly better flexion strength recovery at lower angular velocity compared to a full tibial tunnel technique with DGST for ACL reconstruction.

Microstructure characteristics and mechanical properties of Meretrix lusoria shell.

The microstructure and mechanical properties of Meretrix lusoria shell were investigated. M. lusoria shell was comprised of three layers (outer layer, middle layer and inner layer). Outer layer with serried mastoid structure enhanced the connection strength with middle layer. The middle layer consisted of blocky pattern structure with porosity and crossed-lamellar structure. The inner layer exhibited the typical crossed-lamellar structure. Combined with structure characteristic, phase of aragonite confirmed the crossed-lamellar structure further, building material base for mechanical properties including flexure strength (296.26 MPa), compression strength (6.71 MPa) and crack arrest ability. Microstructure of the shell was the function base of crack deflection phenomenon, which dispersed and defused the applied load via the change of crack extension direction. The investigation of M. lusoria shell provided bionic models for the design and fabrication of bioinspired composites in engineering fields. RESEARCH HIGHLIGHTS: Microstructure and mechanical properties of Meretrix lusoria shell were investigated. Crossed-lamellar structure was the microstructure characterization. M. lusoria shell owned high flexure strength and crack arrest property.

Suspensory Tethers and Critical Point Membrane Displacement in Endolymphatic Hydrops

Abstract Introduction Grossly displaced membranes are characteristic of endolymphatic hydrops. The process whereby physiological membrane displacement becomes pathological may be mediated by stress, but the membrane biomechanics underlying this transition are unclear. Objective This study seeks to determine the role of suspensory tethers during pressure-induced membrane displacement in the generation of the membranous lesions seen in this disease entity using a biomechanical model approach. Methods The location of membrane suspensory tethers was identified histologically. The influence of tethers on model membrane configuration during displacement was assessed graphically. The relationship of membrane configuration during displacement to curvature radius was quantified trigonometrically. The relationship of curvature radius to stress susceptibility was determined mathematically. The net effect of suspensory tethers on membrane stress levels for various degrees of membrane distention and displacement was then calculated numerically. Results In the inferior labyrinth, suspensory tethers are found to occur on the membranes' boundaries. Such tethering is found to impose a biphasic effect on membrane curvature with increasing degrees of displacement. As a consequence, tensile stress susceptibility is found to decline with initial membrane displacement to a critical point nadir beyond which stress then increases monotonically. No such effect was found for the superior labyrinth. Conclusion Boundary tethers in the inferior labyrinth are associated with significant tensile stress reductions until a critical point of membrane displacement is reached. Displacements short of the critical pointmay be physiological and even reversible,whereas such displacements beyond the critical point are apt to be overtly hydropic and irreversible.

Evaluation of tensile strength of tissue adhesives made of fibrin and cyanoacrylate used as reinforcement of colon suture in "ex vivo" swine

ABSTRACT Aim: To evaluate rupture pressures of tissue adhesives of cyanoacrylate (Omnex®) and fibrin (Evicel®), used as reinforcement in colonic suture from "ex vivo" swine. Methods: Surgical procedures were performed in the Surgical Technique Laboratory. From a division in segments of 10 cm of descending colon and sigmoid colon from three "ex vivo" female swine, Landrace breed, which were resected in less than six hours after the slaughter time, 30 segments were selected, 10 of each animal. They were stored in saline solution 0.9% at 36 °C, being randomly allocated in three groups (Control, Evicel and Omnex), each one containing 10 segments. Results: The lower and higher pressure values found in the groups Control, Evicel and Omnex were 36 mmHg and 41 mmHg, 70 mmHg and 90 mmHg, 90 mmHg and 120 mmHg, respectively. Containing statistical significance (p-value <0.0001) concerning the 2 to 2 comparisons (Control, Evicel and Omnex) with 95% trusting rate based on the application of the Turkey Method. Conclusion: One concludes that the use of tissue adhesives in anastomoses colonic in an experimental animal model of "ex vivo" swine increased the anastomoses rupture pressures. Among the tested adhesives, cyanoacrylate presented higher rupture pressure in relation to fibrin adhesive.

RESUMO Objetivo: Avaliar as pressões de ruptura dos adesivos teciduais de Cianoacrilato (Omnex®) e de Fibrina (Evicel®), usados como reforço em suturas colônicas de suínos "ex-vivo". Métodos: Os procedimentos cirúrgicos realizados foram realizados no Laboratório de Técnica Cirúrgica. A partir da divisão em segmentos de 10 cm do colo descendente e colo sigmoide de três suínas fêmeas ex-vivo, da raça Landrace, ressecados em tempo inferior a seis horas em relação ao momento do abate, foram selecionados 30 segmentos, 10 de cada animal. Foram armazenados em soro fisiológico 0,9% a 36 °C, alocando-se aleatoriamente esses segmentos em três grupos (Controle, Evicel e Omnex) com 10 segmentos cada. Resultados: Os menores e maiores valores pressóricos encontrados nos grupos Controle, Evicel e Omnex foram 36 mmHg e 41 mmHg, 70 mmHg e 90 mmHg, 90 mmHg e 120 mmHg, respectivamente. Com significância estatística (Valor-p < 0,0001) para as comparações 2 a 2 (Sutura, Evicel e Omnex) com um intervalo de confiança de 95% construído a partir da aplicação do método de Turkey. Conclusão: A partir desse estudo conclui-se que o uso de adesivos teciduais em anastomoses colônicas, em modelo experimental animal de suíno ex-vivo, aumentou as pressões de ruptura das anastomoses. Dentre os adesivos testados, o adesivo de Cianoacrilato apresentou maiores pressões de ruptura em relação ao adesivo de Fibrina.