Lysgaardellington8247

4-4.7%) and small increases in intradiscal pressure (~1.8-3.4%). Collectively and with due consideration of the risk of fatigue and viscoelastic creep especially under repetitive lifts, current results support a free posture (in between the extreme kyphotic and lordotic postures) with moderate contributions from both active and passive structures during lifting activities involving trunk forward flexion. Muscle architecture parameters change when the muscle changes in length. This has multiple effects on the function of the muscle, e.g. on force production and on contraction velocity. Here we present a versatile geometrical model that predicts changes in muscle architecture as a consequence of length changes of the muscle on the basis of the known architecture at a given muscle length. The model accounts for small changes in aponeuroses' dimensions relative to changes in fascicle length and keeps muscle volume constant. We evaluate the model on the rabbit soleus muscle by comparing model predictions of fascicle lengths and pennation angles with experimental data. For this, we determined the internal architecture of the soleus muscle at different muscle belly lengths (67.8 mm at 35° ankle angle and 59.3 mm at 80° ankle angle). The long and the short soleus muscle exhibited mean fascicle lengths and pennation angles of 20.8 ± 1.3 mm, 4 ± 2° and 13.5 ± 1 mm, 10 ± 4°, respectively. The model predicted reasonable mean fascicle lengths and pennation angles for the long and short soleus that differed only by 1 mm and 1° from the measured data, respectively. Differences between predicted and measured distributions seem to stem from interindividual variability in muscle architecture. Even if the proposed approach has been used for the soleus muscle, which is relatively simple in architecture, it is not restricted to homogeneous unipennate architectures. OSI-774 Perturbed aorta hemodynamics, as for the carotid and the coronary artery, has been identified as potential predicting factor for cardiovascular diseases. In this study, we propose a parametric study based on the computational fluid dynamics with the aim of providing information regarding aortic disease. In particular, the blood flow inside a parametrized aortic arch is computed as a function of morphological changes of baseline aorta geometry. Flow patterns, wall shear stress, time average wall shear stress and oscillatory shear index were calculated during the cardiac cycle. The influence of geometrical changes on the hemodynamics and on these variables was evaluated. The results suggest that the distance between inflow and aortic arch and the angle between aortic arch and descending trunk are the most influencing parameters regarding the WSS-related indices while the effect of the inlet diameter seems limited. In particular, an increase of the aforementioned distance produces a reduction of the spatial distribution of the higher values of the time average wall shear stress and of the oscillatory shear index independently on the other two parameters while an increase of the angle produce an opposite effect. Moreover, as expected, the analysis of the wall shear stress descriptors suggests that the inlet diameter influences only the flow intensity. As conclusion, the proposed parametric study can be used to evaluate the aorta hemodynamics and could be also applied in the future, for analyzing pathological cases and virtual situations, such as pre- and/or post-operative cardiovascular surgical states that present enhanced changes in the aorta morphology yet promoting important variations on the considered indexes. In articular cartilage, the function of chondrocytes is strongly related to their zone-specific microniche geometry defined by pericellular matrix. Microniche geometry is critical for regulating the phenotype and function of the chondrocyte in native cartilage and tissue engineering constructs. However the role of microniche geometry in the mechanical properties and calcium signaling of chondrocytes remains unknown. To recapitulate microniche geometry at single-cell level, we engineered three basic physiological-related polydimethylsiloxane (PDMS) microniches geometries fabricated using soft lithography. We cultured chondrocytes in these microniche geometries and quantified cell mechanical properties using atomic force microscopy (AFM). Fluorescent calcium indicator was used to record and quantify cytosolic Ca2+ oscillation of chondrocytes in different geometries. Our work showed that microniche geometry modulated the mechanical behavior and calcium signaling of chondrocytes. The ellipsoidal microniches significantly enhanced the mechanical properties of chondrocytes compared to spheroidal microniche. Additionally, ellipsoidal microniches can markedly improved the amplitude but weakened the frequency of cytosolic Ca2+ oscillation in chondrocytes than spheroidal microniche. Our work might reveal a novel understanding of chondrocyte mechanotransduction and therefore be useful for designing cell-instructive scaffolds for functional cartilage tissue engineering. Mitral valve (MV) repair with the MitraClip device has been shown to reduce mitral regurgitation severity and improve clinical outcomes in symptomatic patients at high surgical risk. MitraClip was recently approved in the US for the treatment of functional mitral regurgitation (FMR), which significantly expands the number of patients that can be treated with this device. This study aims to quantify the morphologic changes and evaluate the biomechanical interaction between the MitraClip device and the mitral apparatus of a real patient case with FMR using computational modeling. MitraClip procedures using a central and a lateral clip were simulated in a validated MV-left ventricle finite element (FE) model with severe MR. The patient-specific model integrated detailed geometries of the left ventricle, mitral leaflets and chordae, incorporated age- and gender-matched nonlinear hyperelastic human material properties, and accounted for chordae tethering forces. Central and lateral positioning gave similar biomechanical outcomes resulting in an improved but incomplete MV coaptation. Antero-posterior distance, annulus area, valve opening orifice area, and regurgitant orifice area decreased by up to 26%, 19%, 48% and 63% when compared to the pre-clip model, respectively. Anterior and posterior leaflet peak stresses increased by up to 64% and 62% after clip placement, respectively, and were located at the region of clip grasp. Similarly, anterior and posterior leaflet peak strains increased by up to 20% and 10%, respectively. FE modeling, as used here, can be a powerful tool to examine the complex MitraClip-host biomechanical interaction. BACKGROUND/PURPOSE The success rate of early thoracoscopic debridement (TD) for childhood empyema was reviewed in light of the increasing reported incidence of empyema associated with pulmonary necrosis (PN). METHODS Data were collected from 106 patients who underwent thoracoscopic intervention from 2010 to 2016. Twenty additional patients with severe PN/Bronchopleural Fistula (BPF) were not suitable for TD requiring thoracotomy and Serratus anterior digitation flap. RESULTS 106 patients with a median age of 4 years (IQR 2-6 years) were considered for TD as primary intervention of which 3 needed conversion to thoracotomy. TD alone was successful in 93/106 however, 10 patients required subsequent minithoracotomy for PN/BPF (managed with Serratus anterior digitation flap). Counting conversions as failure, the overall success rate of TD was 88%. No statistical difference was demonstrable in success rate compared to our previous series (93% (106/114) vs 88% (93/106)). CONCLUSIONS Primary TD in pediatric empyema is associated with an excellent outcome achieving adequate drainage and full expansion of the lung. The majority of failures in our series were attributable to PN/BPF, requiring thoracotomy and Serratus anterior digitation flap. This is likely a consequence of the increasing incidence of necrotizing pneumonia. LEVEL OF EVIDENCE Level IV. PURPOSE Laparoscopy is commonplace in pediatric surgery. Abdominal access via the umbilicus may present a unique challenge in neonates and young infants predisposing them to complications. We hypothesized that these complications may occur more than described in the literature. METHODS Members of the American Pediatric Surgical Association (APSA) were anonymously surveyed in February of 2018 via REDCap™ regarding technique of umbilical access in infants less than 3 months of age and complications experienced during umbilical access. Approval was obtained from the IRB and the APSA Outcomes and Evidence-based Practice Committee. RESULTS The response rate was 31.3% (329/1050). 62.3% of respondents performed 21 or greater neonatal laparoscopic procedures annually. 34 of 322 respondents reported a direct complication from umbilical access for laparoscopy in this age group (10.6%). Surgeons described 37 specific cases with complications related to umbilical access, with laparoscopic pyloromyotomy making up 47.2% (17/36). CO2 embolism was the most common complication; 15.4% of surgeons reported not knowing about the possibility of CO2 embolism. 41% of surgeons confirm intraabdominal placement of the umbilical trocar prior to insufflation. There was no association between any complication and where the umbilical trocar was placed (above/below/through umbilicus) or placement technique in patients with no umbilical cord stump. There may be an association between complication and where the umbilicus is entered in patients with an umbilical cord stump still in place (p = 0.013). CONCLUSIONS Umbilical access for laparoscopy in neonates and infants less than 3 months of age can present a unique challenge and result in significant complications. All techniques and methods had complications. Surgeons should be aware of these risks and be prepared to manage them emergently if they arise. LEVEL OF EVIDENCE V, expert opinion. The aim of the present study was to isolate, select and characterize endophytic bacteria in rice inhibiting Burkholderia glumae THT as well as to characterize the genetic diversity and virulence factors in strains of B. glumae and Burkholderia gladioli of rice. Rice plants were collected in 4 departments from the northern region of Peru, isolating endophytic bacteria, after tissue sterilization, at 30°C (48h) in Trypticase Soy Agar (TSA), evaluating the antimicrobial activity against B. link2 glumae THT, production of siderophores, resistance of toxoflavine and partial sequencing of the 16S rRNA gene. Furthermore, B. glumae and B. gladioli were isolated in selective medium (pH 4.5) at 41°C/72h. Molecular identification was performed using BOX-PCR and sequencing of the 16S rRNA gene, in addition to the production of extracellular enzymes, motility tests and sensitivity/resistance to bactericides. One hundred and eighty nine (189) endophytic bacteria were isolated, and only 9 strains showed antimicrobial activity against B. glumae THT, highlighting Burkholderia vietnamiensis TUR04-01, B. vietnamiensis TUR04-03 and Bacillus aryabhattai AMH12-02. link3 The strains produced siderophores and at least 55.5% were resistant to toxoflavin. Additionally, 17 strains were grouped into 9 BOX-PCR profiles, where 16 had similarity with B. glumae LMG2196T (100%) and 1 with B. gladioli NBRC 13700T (99.86%). High diversity was found according to geographical origin and virulence factors. In conclusion, strains of the genus Bacillus and Burkholderia are potential biocontrol agents against B. glumae.